461 files changed, 144552 insertions, 0 deletions

diff --git a/app/core/Makefile.am b/app/core/Makefile.am
new file mode 100644
index 0000000..c25f302
--- /dev/null
+++ b/app/core/Makefile.am
@@ -0,0 +1,550 @@
+## Process this file with automake to produce Makefile.in
+
+if PLATFORM_OSX
+xobjective_c = "-xobjective-c"
+xobjective_cxx = "-xobjective-c++"
+xnone = "-xnone"
+endif
+
+AM_CPPFLAGS = \
+	-DGIMPDIR=\""$(gimpdir)"\"			\
+	-DGIMP_APP_VERSION=\"$(GIMP_APP_VERSION)\"	\
+	-DGIMP_USER_VERSION=\"$(GIMP_USER_VERSION)\"	\
+	-DG_LOG_DOMAIN=\"Gimp-Core\"			\
+	-I$(top_builddir)				\
+	-I$(top_srcdir)					\
+	-I$(top_builddir)/app				\
+	-I$(top_srcdir)/app				\
+	$(CAIRO_CFLAGS)					\
+	$(GEGL_CFLAGS)					\
+	$(GDK_PIXBUF_CFLAGS)				\
+	$(LIBMYPAINT_CFLAGS)				\
+	$(MYPAINT_BRUSHES_CFLAGS)			\
+	$(GEXIV2_CFLAGS)				\
+	$(LIBUNWIND_CFLAGS)				\
+	-I$(includedir)
+
+AM_CFLAGS = \
+	$(xobjective_c)
+
+AM_CXXFLAGS = \
+	$(xobjective_cxx)
+
+AM_LDFLAGS = \
+	$(xnone)
+
+noinst_LIBRARIES = libappcore.a
+
+libappcore_a_sources = \
+	core-enums.h				\
+	core-types.h				\
+	gimp.c					\
+	gimp.h					\
+	gimp-atomic.c				\
+	gimp-atomic.h				\
+	gimp-batch.c				\
+	gimp-batch.h				\
+	gimp-cairo.c				\
+	gimp-cairo.h				\
+	gimp-contexts.c				\
+	gimp-contexts.h				\
+	gimp-data-factories.c			\
+	gimp-data-factories.h			\
+	gimp-edit.c				\
+	gimp-edit.h				\
+	gimp-filter-history.c			\
+	gimp-filter-history.h			\
+	gimp-gradients.c			\
+	gimp-gradients.h			\
+	gimp-gui.c				\
+	gimp-gui.h				\
+	gimp-internal-data.c			\
+	gimp-internal-data.h			\
+	gimp-memsize.c				\
+	gimp-memsize.h				\
+	gimp-modules.c				\
+	gimp-modules.h				\
+	gimp-palettes.c				\
+	gimp-palettes.h				\
+	gimp-parallel.cc			\
+	gimp-parallel.h				\
+	gimp-parasites.c			\
+	gimp-parasites.h			\
+	gimp-spawn.c				\
+	gimp-spawn.h				\
+	gimp-tags.c				\
+	gimp-tags.h				\
+	gimp-templates.c			\
+	gimp-templates.h			\
+	gimp-transform-resize.c			\
+	gimp-transform-resize.h			\
+	gimp-transform-3d-utils.c		\
+	gimp-transform-3d-utils.h		\
+	gimp-transform-utils.c			\
+	gimp-transform-utils.h			\
+	gimp-units.c				\
+	gimp-units.h				\
+	gimp-user-install.c			\
+	gimp-user-install.h			\
+	gimp-utils.c				\
+	gimp-utils.h				\
+	gimpasync.c				\
+	gimpasync.h				\
+	gimpasyncset.c				\
+	gimpasyncset.h				\
+	gimpauxitem.c				\
+	gimpauxitem.h				\
+	gimpauxitemundo.c			\
+	gimpauxitemundo.h			\
+	gimpbacktrace.h				\
+	gimpbacktrace-backend.h			\
+	gimpbacktrace-linux.c			\
+	gimpbacktrace-none.c			\
+	gimpbacktrace-windows.c			\
+	gimpbezierdesc.h			\
+	gimpbezierdesc.c			\
+	gimpboundary.c				\
+	gimpboundary.h				\
+	gimpbrush.c				\
+	gimpbrush.h				\
+	gimpbrush-boundary.c			\
+	gimpbrush-boundary.h			\
+	gimpbrush-header.h			\
+	gimpbrush-load.c			\
+	gimpbrush-load.h			\
+	gimpbrush-mipmap.cc			\
+	gimpbrush-mipmap.h			\
+	gimpbrush-private.h			\
+	gimpbrush-save.c			\
+	gimpbrush-save.h			\
+	gimpbrush-transform.cc			\
+	gimpbrush-transform.h			\
+	gimpbrushcache.c			\
+	gimpbrushcache.h			\
+	gimpbrushclipboard.c			\
+	gimpbrushclipboard.h			\
+	gimpbrushgenerated.c			\
+	gimpbrushgenerated.h			\
+	gimpbrushgenerated-load.c		\
+	gimpbrushgenerated-load.h		\
+	gimpbrushgenerated-save.c		\
+	gimpbrushgenerated-save.h		\
+	gimpbrushpipe.c				\
+	gimpbrushpipe.h				\
+	gimpbrushpipe-load.c			\
+	gimpbrushpipe-load.h			\
+	gimpbrushpipe-save.c			\
+	gimpbrushpipe-save.h			\
+	gimpbuffer.c				\
+	gimpbuffer.h				\
+	gimpcancelable.c			\
+	gimpcancelable.h			\
+	gimpchannel.c				\
+	gimpchannel.h				\
+	gimpchannel-combine.c			\
+	gimpchannel-combine.h			\
+	gimpchannel-select.c			\
+	gimpchannel-select.h			\
+	gimpchannelpropundo.c			\
+	gimpchannelpropundo.h			\
+	gimpchannelundo.c			\
+	gimpchannelundo.h			\
+	gimpchunkiterator.c			\
+	gimpchunkiterator.h			\
+	gimpcontainer.c				\
+	gimpcontainer.h				\
+	gimpcontainer-filter.c			\
+	gimpcontainer-filter.h			\
+	gimpcontext.c				\
+	gimpcontext.h				\
+	gimpcoords.c				\
+	gimpcoords.h				\
+	gimpcoords-interpolate.c		\
+	gimpcoords-interpolate.h		\
+	gimpcurve.c				\
+	gimpcurve.h				\
+	gimpcurve-load.c			\
+	gimpcurve-load.h			\
+	gimpcurve-map.c				\
+	gimpcurve-map.h				\
+	gimpcurve-save.c			\
+	gimpcurve-save.h			\
+	gimpdashpattern.c			\
+	gimpdashpattern.h			\
+	gimpdata.c				\
+	gimpdata.h				\
+	gimpdatafactory.c			\
+	gimpdatafactory.h			\
+	gimpdataloaderfactory.c			\
+	gimpdataloaderfactory.h			\
+	gimpdocumentlist.c			\
+	gimpdocumentlist.h			\
+	gimpdrawable.c				\
+	gimpdrawable.h				\
+	gimpdrawable-bucket-fill.c		\
+	gimpdrawable-bucket-fill.h		\
+	gimpdrawable-combine.c			\
+	gimpdrawable-combine.h			\
+	gimpdrawable-edit.c			\
+	gimpdrawable-edit.h			\
+	gimpdrawable-equalize.c			\
+	gimpdrawable-equalize.h			\
+	gimpdrawable-fill.c			\
+	gimpdrawable-fill.h			\
+	gimpdrawable-filters.c			\
+	gimpdrawable-filters.h			\
+	gimpdrawable-floating-selection.c	\
+	gimpdrawable-floating-selection.h	\
+	gimpdrawable-foreground-extract.c	\
+	gimpdrawable-foreground-extract.h	\
+	gimpdrawable-gradient.c			\
+	gimpdrawable-gradient.h			\
+	gimpdrawable-histogram.c		\
+	gimpdrawable-histogram.h		\
+	gimpdrawable-levels.c			\
+	gimpdrawable-levels.h			\
+	gimpdrawable-offset.c			\
+	gimpdrawable-offset.h			\
+	gimpdrawable-operation.c		\
+	gimpdrawable-operation.h		\
+	gimpdrawable-preview.c			\
+	gimpdrawable-preview.h			\
+	gimpdrawable-private.h			\
+	gimpdrawable-shadow.c			\
+	gimpdrawable-shadow.h			\
+	gimpdrawable-stroke.c			\
+	gimpdrawable-stroke.h			\
+	gimpdrawable-transform.c		\
+	gimpdrawable-transform.h		\
+	gimpdrawablefilter.c			\
+	gimpdrawablefilter.h			\
+	gimpdrawablemodundo.c			\
+	gimpdrawablemodundo.h			\
+	gimpdrawablestack.c			\
+	gimpdrawablestack.h			\
+	gimpdrawableundo.c			\
+	gimpdrawableundo.h			\
+	gimpdynamics.c				\
+	gimpdynamics.h				\
+	gimpdynamics-load.c			\
+	gimpdynamics-load.h			\
+	gimpdynamics-save.c			\
+	gimpdynamics-save.h			\
+	gimpdynamicsoutput.c			\
+	gimpdynamicsoutput.h			\
+	gimperror.c				\
+	gimperror.h				\
+	gimpfilloptions.c			\
+	gimpfilloptions.h			\
+	gimpfilter.c				\
+	gimpfilter.h				\
+	gimpfilteredcontainer.c			\
+	gimpfilteredcontainer.h			\
+	gimpfilterstack.c			\
+	gimpfilterstack.h			\
+	gimpfloatingselectionundo.c		\
+	gimpfloatingselectionundo.h		\
+	gimpgradient.c				\
+	gimpgradient.h				\
+	gimpgradient-load.c			\
+	gimpgradient-load.h			\
+	gimpgradient-save.c			\
+	gimpgradient-save.h			\
+	gimpgrid.c				\
+	gimpgrid.h				\
+	gimpgrouplayer.c			\
+	gimpgrouplayer.h			\
+	gimpgrouplayerundo.c			\
+	gimpgrouplayerundo.h			\
+	gimpguide.c				\
+	gimpguide.h				\
+	gimpguideundo.c				\
+	gimpguideundo.h				\
+	gimphistogram.c				\
+	gimphistogram.h				\
+	gimpidtable.c				\
+	gimpidtable.h				\
+	gimpimage.c				\
+	gimpimage.h				\
+	gimpimage-arrange.c			\
+	gimpimage-arrange.h			\
+	gimpimage-color-profile.c		\
+	gimpimage-color-profile.h		\
+	gimpimage-colormap.c			\
+	gimpimage-colormap.h			\
+	gimpimage-convert-indexed.c		\
+	gimpimage-convert-indexed.h		\
+	gimpimage-convert-fsdither.h		\
+	gimpimage-convert-data.h		\
+	gimpimage-convert-precision.c		\
+	gimpimage-convert-precision.h		\
+	gimpimage-convert-type.c		\
+	gimpimage-convert-type.h		\
+	gimpimage-crop.c			\
+	gimpimage-crop.h			\
+	gimpimage-duplicate.c			\
+	gimpimage-duplicate.h			\
+	gimpimage-flip.c			\
+	gimpimage-flip.h			\
+	gimpimage-grid.h                	\
+	gimpimage-grid.c                	\
+	gimpimage-guides.c			\
+	gimpimage-guides.h			\
+	gimpimage-item-list.c			\
+	gimpimage-item-list.h			\
+	gimpimage-merge.c			\
+	gimpimage-merge.h			\
+	gimpimage-metadata.c			\
+	gimpimage-metadata.h			\
+	gimpimage-new.c				\
+	gimpimage-new.h				\
+	gimpimage-pick-color.c			\
+	gimpimage-pick-color.h			\
+	gimpimage-pick-item.c			\
+	gimpimage-pick-item.h			\
+	gimpimage-preview.c			\
+	gimpimage-preview.h			\
+	gimpimage-private.h			\
+	gimpimage-quick-mask.c			\
+	gimpimage-quick-mask.h			\
+	gimpimage-resize.c			\
+	gimpimage-resize.h			\
+	gimpimage-rotate.c			\
+	gimpimage-rotate.h			\
+	gimpimage-sample-points.c		\
+	gimpimage-sample-points.h		\
+	gimpimage-scale.c			\
+	gimpimage-scale.h			\
+	gimpimage-snap.c			\
+	gimpimage-snap.h			\
+	gimpimage-symmetry.c			\
+	gimpimage-symmetry.h			\
+	gimpimage-transform.c			\
+	gimpimage-transform.h			\
+	gimpimage-undo.c			\
+	gimpimage-undo.h			\
+	gimpimage-undo-push.c			\
+	gimpimage-undo-push.h			\
+	gimpimageproxy.c			\
+	gimpimageproxy.h			\
+	gimpimageundo.c				\
+	gimpimageundo.h				\
+	gimpimagefile.c				\
+	gimpimagefile.h				\
+	gimpitem.c				\
+	gimpitem.h				\
+	gimpitem-exclusive.c			\
+	gimpitem-exclusive.h			\
+	gimpitem-linked.c			\
+	gimpitem-linked.h			\
+	gimpitem-preview.c			\
+	gimpitem-preview.h			\
+	gimpitempropundo.c			\
+	gimpitempropundo.h			\
+	gimpitemstack.c				\
+	gimpitemstack.h				\
+	gimpitemtree.c				\
+	gimpitemtree.h				\
+	gimpitemundo.c				\
+	gimpitemundo.h				\
+	gimplayer.c				\
+	gimplayer.h				\
+	gimplayer-floating-selection.c		\
+	gimplayer-floating-selection.h		\
+	gimplayer-new.c				\
+	gimplayer-new.h				\
+	gimplayermask.c				\
+	gimplayermask.h				\
+	gimplayermaskpropundo.c			\
+	gimplayermaskpropundo.h			\
+	gimplayermaskundo.c			\
+	gimplayermaskundo.h			\
+	gimplayerpropundo.c			\
+	gimplayerpropundo.h			\
+	gimplayerstack.c			\
+	gimplayerstack.h			\
+	gimplayerundo.c				\
+	gimplayerundo.h				\
+	gimplineart.c				\
+	gimplineart.h				\
+	gimplist.c				\
+	gimplist.h				\
+	gimpmaskundo.c				\
+	gimpmaskundo.h				\
+	gimpmybrush.c				\
+	gimpmybrush.h				\
+	gimpmybrush-load.c			\
+	gimpmybrush-load.h			\
+	gimpmybrush-private.h			\
+	gimpobject.c				\
+	gimpobject.h				\
+	gimpobjectqueue.c			\
+	gimpobjectqueue.h			\
+	gimppaintinfo.c				\
+	gimppaintinfo.h				\
+	gimppattern.c				\
+	gimppattern.h				\
+	gimppattern-header.h			\
+	gimppattern-load.c			\
+	gimppattern-load.h			\
+	gimppattern-save.c			\
+	gimppattern-save.h			\
+	gimppatternclipboard.c			\
+	gimppatternclipboard.h			\
+	gimppalette.c				\
+	gimppalette.h				\
+	gimppalette-import.c			\
+	gimppalette-import.h			\
+	gimppalette-load.c			\
+	gimppalette-load.h			\
+	gimppalette-save.c			\
+	gimppalette-save.h			\
+	gimppalettemru.c			\
+	gimppalettemru.h			\
+	gimpparamspecs.c			\
+	gimpparamspecs.h			\
+	gimpparamspecs-desc.c			\
+	gimpparamspecs-desc.h			\
+	gimpparamspecs-duplicate.c		\
+	gimpparamspecs-duplicate.h		\
+	gimpparasitelist.c			\
+	gimpparasitelist.h			\
+	gimppdbprogress.c			\
+	gimppdbprogress.h			\
+	gimppickable.c				\
+	gimppickable.h				\
+	gimppickable-auto-shrink.c		\
+	gimppickable-auto-shrink.h		\
+	gimppickable-contiguous-region.cc	\
+	gimppickable-contiguous-region.h	\
+	gimpprogress.c				\
+	gimpprogress.h				\
+	gimpprojectable.c			\
+	gimpprojectable.h			\
+	gimpprojection.c			\
+	gimpprojection.h			\
+	gimpsamplepoint.c			\
+	gimpsamplepoint.h			\
+	gimpsamplepointundo.c			\
+	gimpsamplepointundo.h			\
+	gimpscanconvert.c			\
+	gimpscanconvert.h			\
+	gimpselection.c				\
+	gimpselection.h				\
+	gimpsettings.c				\
+	gimpsettings.h				\
+	gimpstrokeoptions.c			\
+	gimpstrokeoptions.h			\
+	gimpsubprogress.c			\
+	gimpsubprogress.h			\
+	gimpsymmetry.c				\
+	gimpsymmetry.h				\
+	gimpsymmetry-mandala.c			\
+	gimpsymmetry-mandala.h			\
+	gimpsymmetry-mirror.c			\
+	gimpsymmetry-mirror.h			\
+	gimpsymmetry-tiling.c			\
+	gimpsymmetry-tiling.h			\
+	gimptag.c				\
+	gimptag.h				\
+	gimptagcache.c				\
+	gimptagcache.h				\
+	gimptagged.c				\
+	gimptagged.h				\
+	gimptaggedcontainer.c			\
+	gimptaggedcontainer.h			\
+	gimptempbuf.c				\
+	gimptempbuf.h				\
+	gimptemplate.c				\
+	gimptemplate.h				\
+	gimptilehandlerprojectable.c		\
+	gimptilehandlerprojectable.h		\
+	gimptoolgroup.c				\
+	gimptoolgroup.h				\
+	gimptoolinfo.c				\
+	gimptoolinfo.h				\
+	gimptoolitem.c				\
+	gimptoolitem.h				\
+	gimptooloptions.c			\
+	gimptooloptions.h			\
+	gimptoolpreset.c			\
+	gimptoolpreset.h			\
+	gimptoolpreset-load.c			\
+	gimptoolpreset-load.h			\
+	gimptoolpreset-save.c			\
+	gimptoolpreset-save.h			\
+	gimptreehandler.c			\
+	gimptreehandler.h			\
+	gimptreeproxy.c				\
+	gimptreeproxy.h				\
+	gimptriviallycancelablewaitable.c	\
+	gimptriviallycancelablewaitable.h	\
+	gimpuncancelablewaitable.c		\
+	gimpuncancelablewaitable.h		\
+	gimpunit.c				\
+	gimpunit.h				\
+	gimpundo.c				\
+	gimpundo.h				\
+	gimpundostack.c				\
+	gimpundostack.h				\
+	gimpviewable.c				\
+	gimpviewable.h				\
+	gimpwaitable.c				\
+	gimpwaitable.h
+
+libappcore_a_built_sources = \
+	core-enums.c	\
+	gimpmarshal.c	\
+	gimpmarshal.h
+
+libappcore_a_extra_sources = \
+	gimpmarshal.list
+
+libappcore_a_SOURCES = $(libappcore_a_built_sources) $(libappcore_a_sources)
+
+BUILT_SOURCES = \
+	$(libappcore_a_built_sources)
+
+EXTRA_DIST = \
+	$(libappcore_a_extra_sources)
+
+#
+# rules to generate built sources
+#
+# setup autogeneration dependencies
+gen_sources = xgen-gmh xgen-gmc xgen-cec
+CLEANFILES = $(gen_sources)
+
+gimpmarshal.h: $(srcdir)/gimpmarshal.list
+	$(AM_V_GEN) $(GLIB_GENMARSHAL) --prefix=gimp_marshal $(srcdir)/gimpmarshal.list --header >> xgen-gmh \
+	&& (cmp -s xgen-gmh $(@F) || cp xgen-gmh $(@F)) \
+	&& rm -f xgen-gmh xgen-gmh~
+
+gimpmarshal.c: gimpmarshal.h
+	$(AM_V_GEN) $(GLIB_GENMARSHAL) --prefix=gimp_marshal $(srcdir)/gimpmarshal.list --header --body >> xgen-gmc \
+	&& cp xgen-gmc $(@F) \
+	&& rm -f xgen-gmc xgen-gmc~
+
+xgen-cec: $(srcdir)/core-enums.h $(GIMP_MKENUMS) Makefile.am
+	$(AM_V_GEN) $(GIMP_MKENUMS) \
+		--fhead "#include \"config.h\"\n#include <gio/gio.h>\n#include \"libgimpbase/gimpbase.h\"\n#include \"core-enums.h\"\n#include \"gimp-intl.h\"" \
+		--fprod "\n/* enumerations from \"@basename@\" */" \
+		--vhead "GType\n@enum_name@_get_type (void)\n{\n  static const G@Type@Value values[] =\n  {" \
+		--vprod "    { @VALUENAME@, \"@VALUENAME@\", \"@valuenick@\" }," \
+		--vtail "    { 0, NULL, NULL }\n  };\n" \
+		--dhead "  static const Gimp@Type@Desc descs[] =\n  {" \
+		--dprod "    { @VALUENAME@, @valuedesc@, @valuehelp@ },@if ('@valueabbrev@' ne 'NULL')@\n    /* Translators: this is an abbreviated version of @valueudesc@.\n       Keep it short. */\n    { @VALUENAME@, @valueabbrev@, NULL },@endif@" \
+		--dtail "    { 0, NULL, NULL }\n  };\n\n  static GType type = 0;\n\n  if (G_UNLIKELY (! type))\n    {\n      type = g_@type@_register_static (\"@EnumName@\", values);\n      gimp_type_set_translation_context (type, \"@enumnick@\");\n      gimp_@type@_set_value_descriptions (type, descs);\n    }\n\n  return type;\n}\n" \
+		$< > $@
+
+# copy the generated enum file back to the source directory only if it's
+# changed; otherwise, only update its timestamp, so that the recipe isn't
+# executed again on the next build, however, allow this to (harmlessly) fail,
+# to support building from a read-only source tree.
+$(srcdir)/core-enums.c: xgen-cec
+	$(AM_V_GEN) if ! cmp -s $< $@; then \
+		cp $< $@; \
+	else \
+		touch $@ 2> /dev/null \
+		|| true; \
+	fi
diff --git a/app/core/Makefile.in b/app/core/Makefile.in
new file mode 100644
index 0000000..0d84372
--- /dev/null
+++ b/app/core/Makefile.in
@@ -0,0 +1,2438 @@
+# Makefile.in generated by automake 1.16.3 from Makefile.am.
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+ac_ct_DUMPBIN = @ac_ct_DUMPBIN@
+am__include = @am__include@
+am__leading_dot = @am__leading_dot@
+am__quote = @am__quote@
+am__tar = @am__tar@
+am__untar = @am__untar@
+bindir = @bindir@
+build = @build@
+build_alias = @build_alias@
+build_cpu = @build_cpu@
+build_os = @build_os@
+build_vendor = @build_vendor@
+builddir = @builddir@
+datadir = @datadir@
+datarootdir = @datarootdir@
+docdir = @docdir@
+dvidir = @dvidir@
+exec_prefix = @exec_prefix@
+gimpdatadir = @gimpdatadir@
+gimpdir = @gimpdir@
+gimplocaledir = @gimplocaledir@
+gimpplugindir = @gimpplugindir@
+gimpsysconfdir = @gimpsysconfdir@
+host = @host@
+host_alias = @host_alias@
+host_cpu = @host_cpu@
+host_os = @host_os@
+host_vendor = @host_vendor@
+htmldir = @htmldir@
+includedir = @includedir@
+infodir = @infodir@
+install_sh = @install_sh@
+intltool__v_merge_options_ = @intltool__v_merge_options_@
+intltool__v_merge_options_0 = @intltool__v_merge_options_0@
+libdir = @libdir@
+libexecdir = @libexecdir@
+localedir = @localedir@
+localstatedir = @localstatedir@
+mandir = @mandir@
+manpage_gimpdir = @manpage_gimpdir@
+mkdir_p = @mkdir_p@
+ms_librarian = @ms_librarian@
+mypaint_brushes_dir = @mypaint_brushes_dir@
+oldincludedir = @oldincludedir@
+pdfdir = @pdfdir@
+pkgpyexecdir = @pkgpyexecdir@
+pkgpythondir = @pkgpythondir@
+prefix = @prefix@
+program_transform_name = @program_transform_name@
+psdir = @psdir@
+pyexecdir = @pyexecdir@
+pythondir = @pythondir@
+runstatedir = @runstatedir@
+sbindir = @sbindir@
+sharedstatedir = @sharedstatedir@
+srcdir = @srcdir@
+sysconfdir = @sysconfdir@
+target_alias = @target_alias@
+top_build_prefix = @top_build_prefix@
+top_builddir = @top_builddir@
+top_srcdir = @top_srcdir@
+@PLATFORM_OSX_TRUE@xobjective_c = "-xobjective-c"
+@PLATFORM_OSX_TRUE@xobjective_cxx = "-xobjective-c++"
+@PLATFORM_OSX_TRUE@xnone = "-xnone"
+AM_CPPFLAGS = \
+	-DGIMPDIR=\""$(gimpdir)"\"			\
+	-DGIMP_APP_VERSION=\"$(GIMP_APP_VERSION)\"	\
+	-DGIMP_USER_VERSION=\"$(GIMP_USER_VERSION)\"	\
+	-DG_LOG_DOMAIN=\"Gimp-Core\"			\
+	-I$(top_builddir)				\
+	-I$(top_srcdir)					\
+	-I$(top_builddir)/app				\
+	-I$(top_srcdir)/app				\
+	$(CAIRO_CFLAGS)					\
+	$(GEGL_CFLAGS)					\
+	$(GDK_PIXBUF_CFLAGS)				\
+	$(LIBMYPAINT_CFLAGS)				\
+	$(MYPAINT_BRUSHES_CFLAGS)			\
+	$(GEXIV2_CFLAGS)				\
+	$(LIBUNWIND_CFLAGS)				\
+	-I$(includedir)
+
+AM_CFLAGS = \
+	$(xobjective_c)
+
+AM_CXXFLAGS = \
+	$(xobjective_cxx)
+
+AM_LDFLAGS = \
+	$(xnone)
+
+noinst_LIBRARIES = libappcore.a
+libappcore_a_sources = \
+	core-enums.h				\
+	core-types.h				\
+	gimp.c					\
+	gimp.h					\
+	gimp-atomic.c				\
+	gimp-atomic.h				\
+	gimp-batch.c				\
+	gimp-batch.h				\
+	gimp-cairo.c				\
+	gimp-cairo.h				\
+	gimp-contexts.c				\
+	gimp-contexts.h				\
+	gimp-data-factories.c			\
+	gimp-data-factories.h			\
+	gimp-edit.c				\
+	gimp-edit.h				\
+	gimp-filter-history.c			\
+	gimp-filter-history.h			\
+	gimp-gradients.c			\
+	gimp-gradients.h			\
+	gimp-gui.c				\
+	gimp-gui.h				\
+	gimp-internal-data.c			\
+	gimp-internal-data.h			\
+	gimp-memsize.c				\
+	gimp-memsize.h				\
+	gimp-modules.c				\
+	gimp-modules.h				\
+	gimp-palettes.c				\
+	gimp-palettes.h				\
+	gimp-parallel.cc			\
+	gimp-parallel.h				\
+	gimp-parasites.c			\
+	gimp-parasites.h			\
+	gimp-spawn.c				\
+	gimp-spawn.h				\
+	gimp-tags.c				\
+	gimp-tags.h				\
+	gimp-templates.c			\
+	gimp-templates.h			\
+	gimp-transform-resize.c			\
+	gimp-transform-resize.h			\
+	gimp-transform-3d-utils.c		\
+	gimp-transform-3d-utils.h		\
+	gimp-transform-utils.c			\
+	gimp-transform-utils.h			\
+	gimp-units.c				\
+	gimp-units.h				\
+	gimp-user-install.c			\
+	gimp-user-install.h			\
+	gimp-utils.c				\
+	gimp-utils.h				\
+	gimpasync.c				\
+	gimpasync.h				\
+	gimpasyncset.c				\
+	gimpasyncset.h				\
+	gimpauxitem.c				\
+	gimpauxitem.h				\
+	gimpauxitemundo.c			\
+	gimpauxitemundo.h			\
+	gimpbacktrace.h				\
+	gimpbacktrace-backend.h			\
+	gimpbacktrace-linux.c			\
+	gimpbacktrace-none.c			\
+	gimpbacktrace-windows.c			\
+	gimpbezierdesc.h			\
+	gimpbezierdesc.c			\
+	gimpboundary.c				\
+	gimpboundary.h				\
+	gimpbrush.c				\
+	gimpbrush.h				\
+	gimpbrush-boundary.c			\
+	gimpbrush-boundary.h			\
+	gimpbrush-header.h			\
+	gimpbrush-load.c			\
+	gimpbrush-load.h			\
+	gimpbrush-mipmap.cc			\
+	gimpbrush-mipmap.h			\
+	gimpbrush-private.h			\
+	gimpbrush-save.c			\
+	gimpbrush-save.h			\
+	gimpbrush-transform.cc			\
+	gimpbrush-transform.h			\
+	gimpbrushcache.c			\
+	gimpbrushcache.h			\
+	gimpbrushclipboard.c			\
+	gimpbrushclipboard.h			\
+	gimpbrushgenerated.c			\
+	gimpbrushgenerated.h			\
+	gimpbrushgenerated-load.c		\
+	gimpbrushgenerated-load.h		\
+	gimpbrushgenerated-save.c		\
+	gimpbrushgenerated-save.h		\
+	gimpbrushpipe.c				\
+	gimpbrushpipe.h				\
+	gimpbrushpipe-load.c			\
+	gimpbrushpipe-load.h			\
+	gimpbrushpipe-save.c			\
+	gimpbrushpipe-save.h			\
+	gimpbuffer.c				\
+	gimpbuffer.h				\
+	gimpcancelable.c			\
+	gimpcancelable.h			\
+	gimpchannel.c				\
+	gimpchannel.h				\
+	gimpchannel-combine.c			\
+	gimpchannel-combine.h			\
+	gimpchannel-select.c			\
+	gimpchannel-select.h			\
+	gimpchannelpropundo.c			\
+	gimpchannelpropundo.h			\
+	gimpchannelundo.c			\
+	gimpchannelundo.h			\
+	gimpchunkiterator.c			\
+	gimpchunkiterator.h			\
+	gimpcontainer.c				\
+	gimpcontainer.h				\
+	gimpcontainer-filter.c			\
+	gimpcontainer-filter.h			\
+	gimpcontext.c				\
+	gimpcontext.h				\
+	gimpcoords.c				\
+	gimpcoords.h				\
+	gimpcoords-interpolate.c		\
+	gimpcoords-interpolate.h		\
+	gimpcurve.c				\
+	gimpcurve.h				\
+	gimpcurve-load.c			\
+	gimpcurve-load.h			\
+	gimpcurve-map.c				\
+	gimpcurve-map.h				\
+	gimpcurve-save.c			\
+	gimpcurve-save.h			\
+	gimpdashpattern.c			\
+	gimpdashpattern.h			\
+	gimpdata.c				\
+	gimpdata.h				\
+	gimpdatafactory.c			\
+	gimpdatafactory.h			\
+	gimpdataloaderfactory.c			\
+	gimpdataloaderfactory.h			\
+	gimpdocumentlist.c			\
+	gimpdocumentlist.h			\
+	gimpdrawable.c				\
+	gimpdrawable.h				\
+	gimpdrawable-bucket-fill.c		\
+	gimpdrawable-bucket-fill.h		\
+	gimpdrawable-combine.c			\
+	gimpdrawable-combine.h			\
+	gimpdrawable-edit.c			\
+	gimpdrawable-edit.h			\
+	gimpdrawable-equalize.c			\
+	gimpdrawable-equalize.h			\
+	gimpdrawable-fill.c			\
+	gimpdrawable-fill.h			\
+	gimpdrawable-filters.c			\
+	gimpdrawable-filters.h			\
+	gimpdrawable-floating-selection.c	\
+	gimpdrawable-floating-selection.h	\
+	gimpdrawable-foreground-extract.c	\
+	gimpdrawable-foreground-extract.h	\
+	gimpdrawable-gradient.c			\
+	gimpdrawable-gradient.h			\
+	gimpdrawable-histogram.c		\
+	gimpdrawable-histogram.h		\
+	gimpdrawable-levels.c			\
+	gimpdrawable-levels.h			\
+	gimpdrawable-offset.c			\
+	gimpdrawable-offset.h			\
+	gimpdrawable-operation.c		\
+	gimpdrawable-operation.h		\
+	gimpdrawable-preview.c			\
+	gimpdrawable-preview.h			\
+	gimpdrawable-private.h			\
+	gimpdrawable-shadow.c			\
+	gimpdrawable-shadow.h			\
+	gimpdrawable-stroke.c			\
+	gimpdrawable-stroke.h			\
+	gimpdrawable-transform.c		\
+	gimpdrawable-transform.h		\
+	gimpdrawablefilter.c			\
+	gimpdrawablefilter.h			\
+	gimpdrawablemodundo.c			\
+	gimpdrawablemodundo.h			\
+	gimpdrawablestack.c			\
+	gimpdrawablestack.h			\
+	gimpdrawableundo.c			\
+	gimpdrawableundo.h			\
+	gimpdynamics.c				\
+	gimpdynamics.h				\
+	gimpdynamics-load.c			\
+	gimpdynamics-load.h			\
+	gimpdynamics-save.c			\
+	gimpdynamics-save.h			\
+	gimpdynamicsoutput.c			\
+	gimpdynamicsoutput.h			\
+	gimperror.c				\
+	gimperror.h				\
+	gimpfilloptions.c			\
+	gimpfilloptions.h			\
+	gimpfilter.c				\
+	gimpfilter.h				\
+	gimpfilteredcontainer.c			\
+	gimpfilteredcontainer.h			\
+	gimpfilterstack.c			\
+	gimpfilterstack.h			\
+	gimpfloatingselectionundo.c		\
+	gimpfloatingselectionundo.h		\
+	gimpgradient.c				\
+	gimpgradient.h				\
+	gimpgradient-load.c			\
+	gimpgradient-load.h			\
+	gimpgradient-save.c			\
+	gimpgradient-save.h			\
+	gimpgrid.c				\
+	gimpgrid.h				\
+	gimpgrouplayer.c			\
+	gimpgrouplayer.h			\
+	gimpgrouplayerundo.c			\
+	gimpgrouplayerundo.h			\
+	gimpguide.c				\
+	gimpguide.h				\
+	gimpguideundo.c				\
+	gimpguideundo.h				\
+	gimphistogram.c				\
+	gimphistogram.h				\
+	gimpidtable.c				\
+	gimpidtable.h				\
+	gimpimage.c				\
+	gimpimage.h				\
+	gimpimage-arrange.c			\
+	gimpimage-arrange.h			\
+	gimpimage-color-profile.c		\
+	gimpimage-color-profile.h		\
+	gimpimage-colormap.c			\
+	gimpimage-colormap.h			\
+	gimpimage-convert-indexed.c		\
+	gimpimage-convert-indexed.h		\
+	gimpimage-convert-fsdither.h		\
+	gimpimage-convert-data.h		\
+	gimpimage-convert-precision.c		\
+	gimpimage-convert-precision.h		\
+	gimpimage-convert-type.c		\
+	gimpimage-convert-type.h		\
+	gimpimage-crop.c			\
+	gimpimage-crop.h			\
+	gimpimage-duplicate.c			\
+	gimpimage-duplicate.h			\
+	gimpimage-flip.c			\
+	gimpimage-flip.h			\
+	gimpimage-grid.h                	\
+	gimpimage-grid.c                	\
+	gimpimage-guides.c			\
+	gimpimage-guides.h			\
+	gimpimage-item-list.c			\
+	gimpimage-item-list.h			\
+	gimpimage-merge.c			\
+	gimpimage-merge.h			\
+	gimpimage-metadata.c			\
+	gimpimage-metadata.h			\
+	gimpimage-new.c				\
+	gimpimage-new.h				\
+	gimpimage-pick-color.c			\
+	gimpimage-pick-color.h			\
+	gimpimage-pick-item.c			\
+	gimpimage-pick-item.h			\
+	gimpimage-preview.c			\
+	gimpimage-preview.h			\
+	gimpimage-private.h			\
+	gimpimage-quick-mask.c			\
+	gimpimage-quick-mask.h			\
+	gimpimage-resize.c			\
+	gimpimage-resize.h			\
+	gimpimage-rotate.c			\
+	gimpimage-rotate.h			\
+	gimpimage-sample-points.c		\
+	gimpimage-sample-points.h		\
+	gimpimage-scale.c			\
+	gimpimage-scale.h			\
+	gimpimage-snap.c			\
+	gimpimage-snap.h			\
+	gimpimage-symmetry.c			\
+	gimpimage-symmetry.h			\
+	gimpimage-transform.c			\
+	gimpimage-transform.h			\
+	gimpimage-undo.c			\
+	gimpimage-undo.h			\
+	gimpimage-undo-push.c			\
+	gimpimage-undo-push.h			\
+	gimpimageproxy.c			\
+	gimpimageproxy.h			\
+	gimpimageundo.c				\
+	gimpimageundo.h				\
+	gimpimagefile.c				\
+	gimpimagefile.h				\
+	gimpitem.c				\
+	gimpitem.h				\
+	gimpitem-exclusive.c			\
+	gimpitem-exclusive.h			\
+	gimpitem-linked.c			\
+	gimpitem-linked.h			\
+	gimpitem-preview.c			\
+	gimpitem-preview.h			\
+	gimpitempropundo.c			\
+	gimpitempropundo.h			\
+	gimpitemstack.c				\
+	gimpitemstack.h				\
+	gimpitemtree.c				\
+	gimpitemtree.h				\
+	gimpitemundo.c				\
+	gimpitemundo.h				\
+	gimplayer.c				\
+	gimplayer.h				\
+	gimplayer-floating-selection.c		\
+	gimplayer-floating-selection.h		\
+	gimplayer-new.c				\
+	gimplayer-new.h				\
+	gimplayermask.c				\
+	gimplayermask.h				\
+	gimplayermaskpropundo.c			\
+	gimplayermaskpropundo.h			\
+	gimplayermaskundo.c			\
+	gimplayermaskundo.h			\
+	gimplayerpropundo.c			\
+	gimplayerpropundo.h			\
+	gimplayerstack.c			\
+	gimplayerstack.h			\
+	gimplayerundo.c				\
+	gimplayerundo.h				\
+	gimplineart.c				\
+	gimplineart.h				\
+	gimplist.c				\
+	gimplist.h				\
+	gimpmaskundo.c				\
+	gimpmaskundo.h				\
+	gimpmybrush.c				\
+	gimpmybrush.h				\
+	gimpmybrush-load.c			\
+	gimpmybrush-load.h			\
+	gimpmybrush-private.h			\
+	gimpobject.c				\
+	gimpobject.h				\
+	gimpobjectqueue.c			\
+	gimpobjectqueue.h			\
+	gimppaintinfo.c				\
+	gimppaintinfo.h				\
+	gimppattern.c				\
+	gimppattern.h				\
+	gimppattern-header.h			\
+	gimppattern-load.c			\
+	gimppattern-load.h			\
+	gimppattern-save.c			\
+	gimppattern-save.h			\
+	gimppatternclipboard.c			\
+	gimppatternclipboard.h			\
+	gimppalette.c				\
+	gimppalette.h				\
+	gimppalette-import.c			\
+	gimppalette-import.h			\
+	gimppalette-load.c			\
+	gimppalette-load.h			\
+	gimppalette-save.c			\
+	gimppalette-save.h			\
+	gimppalettemru.c			\
+	gimppalettemru.h			\
+	gimpparamspecs.c			\
+	gimpparamspecs.h			\
+	gimpparamspecs-desc.c			\
+	gimpparamspecs-desc.h			\
+	gimpparamspecs-duplicate.c		\
+	gimpparamspecs-duplicate.h		\
+	gimpparasitelist.c			\
+	gimpparasitelist.h			\
+	gimppdbprogress.c			\
+	gimppdbprogress.h			\
+	gimppickable.c				\
+	gimppickable.h				\
+	gimppickable-auto-shrink.c		\
+	gimppickable-auto-shrink.h		\
+	gimppickable-contiguous-region.cc	\
+	gimppickable-contiguous-region.h	\
+	gimpprogress.c				\
+	gimpprogress.h				\
+	gimpprojectable.c			\
+	gimpprojectable.h			\
+	gimpprojection.c			\
+	gimpprojection.h			\
+	gimpsamplepoint.c			\
+	gimpsamplepoint.h			\
+	gimpsamplepointundo.c			\
+	gimpsamplepointundo.h			\
+	gimpscanconvert.c			\
+	gimpscanconvert.h			\
+	gimpselection.c				\
+	gimpselection.h				\
+	gimpsettings.c				\
+	gimpsettings.h				\
+	gimpstrokeoptions.c			\
+	gimpstrokeoptions.h			\
+	gimpsubprogress.c			\
+	gimpsubprogress.h			\
+	gimpsymmetry.c				\
+	gimpsymmetry.h				\
+	gimpsymmetry-mandala.c			\
+	gimpsymmetry-mandala.h			\
+	gimpsymmetry-mirror.c			\
+	gimpsymmetry-mirror.h			\
+	gimpsymmetry-tiling.c			\
+	gimpsymmetry-tiling.h			\
+	gimptag.c				\
+	gimptag.h				\
+	gimptagcache.c				\
+	gimptagcache.h				\
+	gimptagged.c				\
+	gimptagged.h				\
+	gimptaggedcontainer.c			\
+	gimptaggedcontainer.h			\
+	gimptempbuf.c				\
+	gimptempbuf.h				\
+	gimptemplate.c				\
+	gimptemplate.h				\
+	gimptilehandlerprojectable.c		\
+	gimptilehandlerprojectable.h		\
+	gimptoolgroup.c				\
+	gimptoolgroup.h				\
+	gimptoolinfo.c				\
+	gimptoolinfo.h				\
+	gimptoolitem.c				\
+	gimptoolitem.h				\
+	gimptooloptions.c			\
+	gimptooloptions.h			\
+	gimptoolpreset.c			\
+	gimptoolpreset.h			\
+	gimptoolpreset-load.c			\
+	gimptoolpreset-load.h			\
+	gimptoolpreset-save.c			\
+	gimptoolpreset-save.h			\
+	gimptreehandler.c			\
+	gimptreehandler.h			\
+	gimptreeproxy.c				\
+	gimptreeproxy.h				\
+	gimptriviallycancelablewaitable.c	\
+	gimptriviallycancelablewaitable.h	\
+	gimpuncancelablewaitable.c		\
+	gimpuncancelablewaitable.h		\
+	gimpunit.c				\
+	gimpunit.h				\
+	gimpundo.c				\
+	gimpundo.h				\
+	gimpundostack.c				\
+	gimpundostack.h				\
+	gimpviewable.c				\
+	gimpviewable.h				\
+	gimpwaitable.c				\
+	gimpwaitable.h
+
+libappcore_a_built_sources = \
+	core-enums.c	\
+	gimpmarshal.c	\
+	gimpmarshal.h
+
+libappcore_a_extra_sources = \
+	gimpmarshal.list
+
+libappcore_a_SOURCES = $(libappcore_a_built_sources) $(libappcore_a_sources)
+BUILT_SOURCES = \
+	$(libappcore_a_built_sources)
+
+EXTRA_DIST = \
+	$(libappcore_a_extra_sources)
+
+
+#
+# rules to generate built sources
+#
+# setup autogeneration dependencies
+gen_sources = xgen-gmh xgen-gmc xgen-cec
+CLEANFILES = $(gen_sources)
+all: $(BUILT_SOURCES)
+	$(MAKE) $(AM_MAKEFLAGS) all-am
+
+.SUFFIXES:
+.SUFFIXES: .c .cc .lo .o .obj
+$(srcdir)/Makefile.in: @MAINTAINER_MODE_TRUE@ $(srcdir)/Makefile.am  $(am__configure_deps)
+	@for dep in $?; do \
+	  case '$(am__configure_deps)' in \
+	    *$$dep*) \
+	      ( cd $(top_builddir) && $(MAKE) $(AM_MAKEFLAGS) am--refresh ) \
+	        && { if test -f $@; then exit 0; else break; fi; }; \
+	      exit 1;; \
+	  esac; \
+	done; \
+	echo ' cd $(top_srcdir) && $(AUTOMAKE) --gnu app/core/Makefile'; \
+	$(am__cd) $(top_srcdir) && \
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+	-rm -f ./$(DEPDIR)/gimpimage-guides.Po
+	-rm -f ./$(DEPDIR)/gimpimage-item-list.Po
+	-rm -f ./$(DEPDIR)/gimpimage-merge.Po
+	-rm -f ./$(DEPDIR)/gimpimage-metadata.Po
+	-rm -f ./$(DEPDIR)/gimpimage-new.Po
+	-rm -f ./$(DEPDIR)/gimpimage-pick-color.Po
+	-rm -f ./$(DEPDIR)/gimpimage-pick-item.Po
+	-rm -f ./$(DEPDIR)/gimpimage-preview.Po
+	-rm -f ./$(DEPDIR)/gimpimage-quick-mask.Po
+	-rm -f ./$(DEPDIR)/gimpimage-resize.Po
+	-rm -f ./$(DEPDIR)/gimpimage-rotate.Po
+	-rm -f ./$(DEPDIR)/gimpimage-sample-points.Po
+	-rm -f ./$(DEPDIR)/gimpimage-scale.Po
+	-rm -f ./$(DEPDIR)/gimpimage-snap.Po
+	-rm -f ./$(DEPDIR)/gimpimage-symmetry.Po
+	-rm -f ./$(DEPDIR)/gimpimage-transform.Po
+	-rm -f ./$(DEPDIR)/gimpimage-undo-push.Po
+	-rm -f ./$(DEPDIR)/gimpimage-undo.Po
+	-rm -f ./$(DEPDIR)/gimpimage.Po
+	-rm -f ./$(DEPDIR)/gimpimagefile.Po
+	-rm -f ./$(DEPDIR)/gimpimageproxy.Po
+	-rm -f ./$(DEPDIR)/gimpimageundo.Po
+	-rm -f ./$(DEPDIR)/gimpitem-exclusive.Po
+	-rm -f ./$(DEPDIR)/gimpitem-linked.Po
+	-rm -f ./$(DEPDIR)/gimpitem-preview.Po
+	-rm -f ./$(DEPDIR)/gimpitem.Po
+	-rm -f ./$(DEPDIR)/gimpitempropundo.Po
+	-rm -f ./$(DEPDIR)/gimpitemstack.Po
+	-rm -f ./$(DEPDIR)/gimpitemtree.Po
+	-rm -f ./$(DEPDIR)/gimpitemundo.Po
+	-rm -f ./$(DEPDIR)/gimplayer-floating-selection.Po
+	-rm -f ./$(DEPDIR)/gimplayer-new.Po
+	-rm -f ./$(DEPDIR)/gimplayer.Po
+	-rm -f ./$(DEPDIR)/gimplayermask.Po
+	-rm -f ./$(DEPDIR)/gimplayermaskpropundo.Po
+	-rm -f ./$(DEPDIR)/gimplayermaskundo.Po
+	-rm -f ./$(DEPDIR)/gimplayerpropundo.Po
+	-rm -f ./$(DEPDIR)/gimplayerstack.Po
+	-rm -f ./$(DEPDIR)/gimplayerundo.Po
+	-rm -f ./$(DEPDIR)/gimplineart.Po
+	-rm -f ./$(DEPDIR)/gimplist.Po
+	-rm -f ./$(DEPDIR)/gimpmarshal.Po
+	-rm -f ./$(DEPDIR)/gimpmaskundo.Po
+	-rm -f ./$(DEPDIR)/gimpmybrush-load.Po
+	-rm -f ./$(DEPDIR)/gimpmybrush.Po
+	-rm -f ./$(DEPDIR)/gimpobject.Po
+	-rm -f ./$(DEPDIR)/gimpobjectqueue.Po
+	-rm -f ./$(DEPDIR)/gimppaintinfo.Po
+	-rm -f ./$(DEPDIR)/gimppalette-import.Po
+	-rm -f ./$(DEPDIR)/gimppalette-load.Po
+	-rm -f ./$(DEPDIR)/gimppalette-save.Po
+	-rm -f ./$(DEPDIR)/gimppalette.Po
+	-rm -f ./$(DEPDIR)/gimppalettemru.Po
+	-rm -f ./$(DEPDIR)/gimpparamspecs-desc.Po
+	-rm -f ./$(DEPDIR)/gimpparamspecs-duplicate.Po
+	-rm -f ./$(DEPDIR)/gimpparamspecs.Po
+	-rm -f ./$(DEPDIR)/gimpparasitelist.Po
+	-rm -f ./$(DEPDIR)/gimppattern-load.Po
+	-rm -f ./$(DEPDIR)/gimppattern-save.Po
+	-rm -f ./$(DEPDIR)/gimppattern.Po
+	-rm -f ./$(DEPDIR)/gimppatternclipboard.Po
+	-rm -f ./$(DEPDIR)/gimppdbprogress.Po
+	-rm -f ./$(DEPDIR)/gimppickable-auto-shrink.Po
+	-rm -f ./$(DEPDIR)/gimppickable-contiguous-region.Po
+	-rm -f ./$(DEPDIR)/gimppickable.Po
+	-rm -f ./$(DEPDIR)/gimpprogress.Po
+	-rm -f ./$(DEPDIR)/gimpprojectable.Po
+	-rm -f ./$(DEPDIR)/gimpprojection.Po
+	-rm -f ./$(DEPDIR)/gimpsamplepoint.Po
+	-rm -f ./$(DEPDIR)/gimpsamplepointundo.Po
+	-rm -f ./$(DEPDIR)/gimpscanconvert.Po
+	-rm -f ./$(DEPDIR)/gimpselection.Po
+	-rm -f ./$(DEPDIR)/gimpsettings.Po
+	-rm -f ./$(DEPDIR)/gimpstrokeoptions.Po
+	-rm -f ./$(DEPDIR)/gimpsubprogress.Po
+	-rm -f ./$(DEPDIR)/gimpsymmetry-mandala.Po
+	-rm -f ./$(DEPDIR)/gimpsymmetry-mirror.Po
+	-rm -f ./$(DEPDIR)/gimpsymmetry-tiling.Po
+	-rm -f ./$(DEPDIR)/gimpsymmetry.Po
+	-rm -f ./$(DEPDIR)/gimptag.Po
+	-rm -f ./$(DEPDIR)/gimptagcache.Po
+	-rm -f ./$(DEPDIR)/gimptagged.Po
+	-rm -f ./$(DEPDIR)/gimptaggedcontainer.Po
+	-rm -f ./$(DEPDIR)/gimptempbuf.Po
+	-rm -f ./$(DEPDIR)/gimptemplate.Po
+	-rm -f ./$(DEPDIR)/gimptilehandlerprojectable.Po
+	-rm -f ./$(DEPDIR)/gimptoolgroup.Po
+	-rm -f ./$(DEPDIR)/gimptoolinfo.Po
+	-rm -f ./$(DEPDIR)/gimptoolitem.Po
+	-rm -f ./$(DEPDIR)/gimptooloptions.Po
+	-rm -f ./$(DEPDIR)/gimptoolpreset-load.Po
+	-rm -f ./$(DEPDIR)/gimptoolpreset-save.Po
+	-rm -f ./$(DEPDIR)/gimptoolpreset.Po
+	-rm -f ./$(DEPDIR)/gimptreehandler.Po
+	-rm -f ./$(DEPDIR)/gimptreeproxy.Po
+	-rm -f ./$(DEPDIR)/gimptriviallycancelablewaitable.Po
+	-rm -f ./$(DEPDIR)/gimpuncancelablewaitable.Po
+	-rm -f ./$(DEPDIR)/gimpundo.Po
+	-rm -f ./$(DEPDIR)/gimpundostack.Po
+	-rm -f ./$(DEPDIR)/gimpunit.Po
+	-rm -f ./$(DEPDIR)/gimpviewable.Po
+	-rm -f ./$(DEPDIR)/gimpwaitable.Po
+	-rm -f Makefile
+distclean-am: clean-am distclean-compile distclean-generic \
+	distclean-tags
+
+dvi: dvi-am
+
+dvi-am:
+
+html: html-am
+
+html-am:
+
+info: info-am
+
+info-am:
+
+install-data-am:
+
+install-dvi: install-dvi-am
+
+install-dvi-am:
+
+install-exec-am:
+
+install-html: install-html-am
+
+install-html-am:
+
+install-info: install-info-am
+
+install-info-am:
+
+install-man:
+
+install-pdf: install-pdf-am
+
+install-pdf-am:
+
+install-ps: install-ps-am
+
+install-ps-am:
+
+installcheck-am:
+
+maintainer-clean: maintainer-clean-am
+		-rm -f ./$(DEPDIR)/core-enums.Po
+	-rm -f ./$(DEPDIR)/gimp-atomic.Po
+	-rm -f ./$(DEPDIR)/gimp-batch.Po
+	-rm -f ./$(DEPDIR)/gimp-cairo.Po
+	-rm -f ./$(DEPDIR)/gimp-contexts.Po
+	-rm -f ./$(DEPDIR)/gimp-data-factories.Po
+	-rm -f ./$(DEPDIR)/gimp-edit.Po
+	-rm -f ./$(DEPDIR)/gimp-filter-history.Po
+	-rm -f ./$(DEPDIR)/gimp-gradients.Po
+	-rm -f ./$(DEPDIR)/gimp-gui.Po
+	-rm -f ./$(DEPDIR)/gimp-internal-data.Po
+	-rm -f ./$(DEPDIR)/gimp-memsize.Po
+	-rm -f ./$(DEPDIR)/gimp-modules.Po
+	-rm -f ./$(DEPDIR)/gimp-palettes.Po
+	-rm -f ./$(DEPDIR)/gimp-parallel.Po
+	-rm -f ./$(DEPDIR)/gimp-parasites.Po
+	-rm -f ./$(DEPDIR)/gimp-spawn.Po
+	-rm -f ./$(DEPDIR)/gimp-tags.Po
+	-rm -f ./$(DEPDIR)/gimp-templates.Po
+	-rm -f ./$(DEPDIR)/gimp-transform-3d-utils.Po
+	-rm -f ./$(DEPDIR)/gimp-transform-resize.Po
+	-rm -f ./$(DEPDIR)/gimp-transform-utils.Po
+	-rm -f ./$(DEPDIR)/gimp-units.Po
+	-rm -f ./$(DEPDIR)/gimp-user-install.Po
+	-rm -f ./$(DEPDIR)/gimp-utils.Po
+	-rm -f ./$(DEPDIR)/gimp.Po
+	-rm -f ./$(DEPDIR)/gimpasync.Po
+	-rm -f ./$(DEPDIR)/gimpasyncset.Po
+	-rm -f ./$(DEPDIR)/gimpauxitem.Po
+	-rm -f ./$(DEPDIR)/gimpauxitemundo.Po
+	-rm -f ./$(DEPDIR)/gimpbacktrace-linux.Po
+	-rm -f ./$(DEPDIR)/gimpbacktrace-none.Po
+	-rm -f ./$(DEPDIR)/gimpbacktrace-windows.Po
+	-rm -f ./$(DEPDIR)/gimpbezierdesc.Po
+	-rm -f ./$(DEPDIR)/gimpboundary.Po
+	-rm -f ./$(DEPDIR)/gimpbrush-boundary.Po
+	-rm -f ./$(DEPDIR)/gimpbrush-load.Po
+	-rm -f ./$(DEPDIR)/gimpbrush-mipmap.Po
+	-rm -f ./$(DEPDIR)/gimpbrush-save.Po
+	-rm -f ./$(DEPDIR)/gimpbrush-transform.Po
+	-rm -f ./$(DEPDIR)/gimpbrush.Po
+	-rm -f ./$(DEPDIR)/gimpbrushcache.Po
+	-rm -f ./$(DEPDIR)/gimpbrushclipboard.Po
+	-rm -f ./$(DEPDIR)/gimpbrushgenerated-load.Po
+	-rm -f ./$(DEPDIR)/gimpbrushgenerated-save.Po
+	-rm -f ./$(DEPDIR)/gimpbrushgenerated.Po
+	-rm -f ./$(DEPDIR)/gimpbrushpipe-load.Po
+	-rm -f ./$(DEPDIR)/gimpbrushpipe-save.Po
+	-rm -f ./$(DEPDIR)/gimpbrushpipe.Po
+	-rm -f ./$(DEPDIR)/gimpbuffer.Po
+	-rm -f ./$(DEPDIR)/gimpcancelable.Po
+	-rm -f ./$(DEPDIR)/gimpchannel-combine.Po
+	-rm -f ./$(DEPDIR)/gimpchannel-select.Po
+	-rm -f ./$(DEPDIR)/gimpchannel.Po
+	-rm -f ./$(DEPDIR)/gimpchannelpropundo.Po
+	-rm -f ./$(DEPDIR)/gimpchannelundo.Po
+	-rm -f ./$(DEPDIR)/gimpchunkiterator.Po
+	-rm -f ./$(DEPDIR)/gimpcontainer-filter.Po
+	-rm -f ./$(DEPDIR)/gimpcontainer.Po
+	-rm -f ./$(DEPDIR)/gimpcontext.Po
+	-rm -f ./$(DEPDIR)/gimpcoords-interpolate.Po
+	-rm -f ./$(DEPDIR)/gimpcoords.Po
+	-rm -f ./$(DEPDIR)/gimpcurve-load.Po
+	-rm -f ./$(DEPDIR)/gimpcurve-map.Po
+	-rm -f ./$(DEPDIR)/gimpcurve-save.Po
+	-rm -f ./$(DEPDIR)/gimpcurve.Po
+	-rm -f ./$(DEPDIR)/gimpdashpattern.Po
+	-rm -f ./$(DEPDIR)/gimpdata.Po
+	-rm -f ./$(DEPDIR)/gimpdatafactory.Po
+	-rm -f ./$(DEPDIR)/gimpdataloaderfactory.Po
+	-rm -f ./$(DEPDIR)/gimpdocumentlist.Po
+	-rm -f ./$(DEPDIR)/gimpdrawable-bucket-fill.Po
+	-rm -f ./$(DEPDIR)/gimpdrawable-combine.Po
+	-rm -f ./$(DEPDIR)/gimpdrawable-edit.Po
+	-rm -f ./$(DEPDIR)/gimpdrawable-equalize.Po
+	-rm -f ./$(DEPDIR)/gimpdrawable-fill.Po
+	-rm -f ./$(DEPDIR)/gimpdrawable-filters.Po
+	-rm -f ./$(DEPDIR)/gimpdrawable-floating-selection.Po
+	-rm -f ./$(DEPDIR)/gimpdrawable-foreground-extract.Po
+	-rm -f ./$(DEPDIR)/gimpdrawable-gradient.Po
+	-rm -f ./$(DEPDIR)/gimpdrawable-histogram.Po
+	-rm -f ./$(DEPDIR)/gimpdrawable-levels.Po
+	-rm -f ./$(DEPDIR)/gimpdrawable-offset.Po
+	-rm -f ./$(DEPDIR)/gimpdrawable-operation.Po
+	-rm -f ./$(DEPDIR)/gimpdrawable-preview.Po
+	-rm -f ./$(DEPDIR)/gimpdrawable-shadow.Po
+	-rm -f ./$(DEPDIR)/gimpdrawable-stroke.Po
+	-rm -f ./$(DEPDIR)/gimpdrawable-transform.Po
+	-rm -f ./$(DEPDIR)/gimpdrawable.Po
+	-rm -f ./$(DEPDIR)/gimpdrawablefilter.Po
+	-rm -f ./$(DEPDIR)/gimpdrawablemodundo.Po
+	-rm -f ./$(DEPDIR)/gimpdrawablestack.Po
+	-rm -f ./$(DEPDIR)/gimpdrawableundo.Po
+	-rm -f ./$(DEPDIR)/gimpdynamics-load.Po
+	-rm -f ./$(DEPDIR)/gimpdynamics-save.Po
+	-rm -f ./$(DEPDIR)/gimpdynamics.Po
+	-rm -f ./$(DEPDIR)/gimpdynamicsoutput.Po
+	-rm -f ./$(DEPDIR)/gimperror.Po
+	-rm -f ./$(DEPDIR)/gimpfilloptions.Po
+	-rm -f ./$(DEPDIR)/gimpfilter.Po
+	-rm -f ./$(DEPDIR)/gimpfilteredcontainer.Po
+	-rm -f ./$(DEPDIR)/gimpfilterstack.Po
+	-rm -f ./$(DEPDIR)/gimpfloatingselectionundo.Po
+	-rm -f ./$(DEPDIR)/gimpgradient-load.Po
+	-rm -f ./$(DEPDIR)/gimpgradient-save.Po
+	-rm -f ./$(DEPDIR)/gimpgradient.Po
+	-rm -f ./$(DEPDIR)/gimpgrid.Po
+	-rm -f ./$(DEPDIR)/gimpgrouplayer.Po
+	-rm -f ./$(DEPDIR)/gimpgrouplayerundo.Po
+	-rm -f ./$(DEPDIR)/gimpguide.Po
+	-rm -f ./$(DEPDIR)/gimpguideundo.Po
+	-rm -f ./$(DEPDIR)/gimphistogram.Po
+	-rm -f ./$(DEPDIR)/gimpidtable.Po
+	-rm -f ./$(DEPDIR)/gimpimage-arrange.Po
+	-rm -f ./$(DEPDIR)/gimpimage-color-profile.Po
+	-rm -f ./$(DEPDIR)/gimpimage-colormap.Po
+	-rm -f ./$(DEPDIR)/gimpimage-convert-indexed.Po
+	-rm -f ./$(DEPDIR)/gimpimage-convert-precision.Po
+	-rm -f ./$(DEPDIR)/gimpimage-convert-type.Po
+	-rm -f ./$(DEPDIR)/gimpimage-crop.Po
+	-rm -f ./$(DEPDIR)/gimpimage-duplicate.Po
+	-rm -f ./$(DEPDIR)/gimpimage-flip.Po
+	-rm -f ./$(DEPDIR)/gimpimage-grid.Po
+	-rm -f ./$(DEPDIR)/gimpimage-guides.Po
+	-rm -f ./$(DEPDIR)/gimpimage-item-list.Po
+	-rm -f ./$(DEPDIR)/gimpimage-merge.Po
+	-rm -f ./$(DEPDIR)/gimpimage-metadata.Po
+	-rm -f ./$(DEPDIR)/gimpimage-new.Po
+	-rm -f ./$(DEPDIR)/gimpimage-pick-color.Po
+	-rm -f ./$(DEPDIR)/gimpimage-pick-item.Po
+	-rm -f ./$(DEPDIR)/gimpimage-preview.Po
+	-rm -f ./$(DEPDIR)/gimpimage-quick-mask.Po
+	-rm -f ./$(DEPDIR)/gimpimage-resize.Po
+	-rm -f ./$(DEPDIR)/gimpimage-rotate.Po
+	-rm -f ./$(DEPDIR)/gimpimage-sample-points.Po
+	-rm -f ./$(DEPDIR)/gimpimage-scale.Po
+	-rm -f ./$(DEPDIR)/gimpimage-snap.Po
+	-rm -f ./$(DEPDIR)/gimpimage-symmetry.Po
+	-rm -f ./$(DEPDIR)/gimpimage-transform.Po
+	-rm -f ./$(DEPDIR)/gimpimage-undo-push.Po
+	-rm -f ./$(DEPDIR)/gimpimage-undo.Po
+	-rm -f ./$(DEPDIR)/gimpimage.Po
+	-rm -f ./$(DEPDIR)/gimpimagefile.Po
+	-rm -f ./$(DEPDIR)/gimpimageproxy.Po
+	-rm -f ./$(DEPDIR)/gimpimageundo.Po
+	-rm -f ./$(DEPDIR)/gimpitem-exclusive.Po
+	-rm -f ./$(DEPDIR)/gimpitem-linked.Po
+	-rm -f ./$(DEPDIR)/gimpitem-preview.Po
+	-rm -f ./$(DEPDIR)/gimpitem.Po
+	-rm -f ./$(DEPDIR)/gimpitempropundo.Po
+	-rm -f ./$(DEPDIR)/gimpitemstack.Po
+	-rm -f ./$(DEPDIR)/gimpitemtree.Po
+	-rm -f ./$(DEPDIR)/gimpitemundo.Po
+	-rm -f ./$(DEPDIR)/gimplayer-floating-selection.Po
+	-rm -f ./$(DEPDIR)/gimplayer-new.Po
+	-rm -f ./$(DEPDIR)/gimplayer.Po
+	-rm -f ./$(DEPDIR)/gimplayermask.Po
+	-rm -f ./$(DEPDIR)/gimplayermaskpropundo.Po
+	-rm -f ./$(DEPDIR)/gimplayermaskundo.Po
+	-rm -f ./$(DEPDIR)/gimplayerpropundo.Po
+	-rm -f ./$(DEPDIR)/gimplayerstack.Po
+	-rm -f ./$(DEPDIR)/gimplayerundo.Po
+	-rm -f ./$(DEPDIR)/gimplineart.Po
+	-rm -f ./$(DEPDIR)/gimplist.Po
+	-rm -f ./$(DEPDIR)/gimpmarshal.Po
+	-rm -f ./$(DEPDIR)/gimpmaskundo.Po
+	-rm -f ./$(DEPDIR)/gimpmybrush-load.Po
+	-rm -f ./$(DEPDIR)/gimpmybrush.Po
+	-rm -f ./$(DEPDIR)/gimpobject.Po
+	-rm -f ./$(DEPDIR)/gimpobjectqueue.Po
+	-rm -f ./$(DEPDIR)/gimppaintinfo.Po
+	-rm -f ./$(DEPDIR)/gimppalette-import.Po
+	-rm -f ./$(DEPDIR)/gimppalette-load.Po
+	-rm -f ./$(DEPDIR)/gimppalette-save.Po
+	-rm -f ./$(DEPDIR)/gimppalette.Po
+	-rm -f ./$(DEPDIR)/gimppalettemru.Po
+	-rm -f ./$(DEPDIR)/gimpparamspecs-desc.Po
+	-rm -f ./$(DEPDIR)/gimpparamspecs-duplicate.Po
+	-rm -f ./$(DEPDIR)/gimpparamspecs.Po
+	-rm -f ./$(DEPDIR)/gimpparasitelist.Po
+	-rm -f ./$(DEPDIR)/gimppattern-load.Po
+	-rm -f ./$(DEPDIR)/gimppattern-save.Po
+	-rm -f ./$(DEPDIR)/gimppattern.Po
+	-rm -f ./$(DEPDIR)/gimppatternclipboard.Po
+	-rm -f ./$(DEPDIR)/gimppdbprogress.Po
+	-rm -f ./$(DEPDIR)/gimppickable-auto-shrink.Po
+	-rm -f ./$(DEPDIR)/gimppickable-contiguous-region.Po
+	-rm -f ./$(DEPDIR)/gimppickable.Po
+	-rm -f ./$(DEPDIR)/gimpprogress.Po
+	-rm -f ./$(DEPDIR)/gimpprojectable.Po
+	-rm -f ./$(DEPDIR)/gimpprojection.Po
+	-rm -f ./$(DEPDIR)/gimpsamplepoint.Po
+	-rm -f ./$(DEPDIR)/gimpsamplepointundo.Po
+	-rm -f ./$(DEPDIR)/gimpscanconvert.Po
+	-rm -f ./$(DEPDIR)/gimpselection.Po
+	-rm -f ./$(DEPDIR)/gimpsettings.Po
+	-rm -f ./$(DEPDIR)/gimpstrokeoptions.Po
+	-rm -f ./$(DEPDIR)/gimpsubprogress.Po
+	-rm -f ./$(DEPDIR)/gimpsymmetry-mandala.Po
+	-rm -f ./$(DEPDIR)/gimpsymmetry-mirror.Po
+	-rm -f ./$(DEPDIR)/gimpsymmetry-tiling.Po
+	-rm -f ./$(DEPDIR)/gimpsymmetry.Po
+	-rm -f ./$(DEPDIR)/gimptag.Po
+	-rm -f ./$(DEPDIR)/gimptagcache.Po
+	-rm -f ./$(DEPDIR)/gimptagged.Po
+	-rm -f ./$(DEPDIR)/gimptaggedcontainer.Po
+	-rm -f ./$(DEPDIR)/gimptempbuf.Po
+	-rm -f ./$(DEPDIR)/gimptemplate.Po
+	-rm -f ./$(DEPDIR)/gimptilehandlerprojectable.Po
+	-rm -f ./$(DEPDIR)/gimptoolgroup.Po
+	-rm -f ./$(DEPDIR)/gimptoolinfo.Po
+	-rm -f ./$(DEPDIR)/gimptoolitem.Po
+	-rm -f ./$(DEPDIR)/gimptooloptions.Po
+	-rm -f ./$(DEPDIR)/gimptoolpreset-load.Po
+	-rm -f ./$(DEPDIR)/gimptoolpreset-save.Po
+	-rm -f ./$(DEPDIR)/gimptoolpreset.Po
+	-rm -f ./$(DEPDIR)/gimptreehandler.Po
+	-rm -f ./$(DEPDIR)/gimptreeproxy.Po
+	-rm -f ./$(DEPDIR)/gimptriviallycancelablewaitable.Po
+	-rm -f ./$(DEPDIR)/gimpuncancelablewaitable.Po
+	-rm -f ./$(DEPDIR)/gimpundo.Po
+	-rm -f ./$(DEPDIR)/gimpundostack.Po
+	-rm -f ./$(DEPDIR)/gimpunit.Po
+	-rm -f ./$(DEPDIR)/gimpviewable.Po
+	-rm -f ./$(DEPDIR)/gimpwaitable.Po
+	-rm -f Makefile
+maintainer-clean-am: distclean-am maintainer-clean-generic
+
+mostlyclean: mostlyclean-am
+
+mostlyclean-am: mostlyclean-compile mostlyclean-generic \
+	mostlyclean-libtool
+
+pdf: pdf-am
+
+pdf-am:
+
+ps: ps-am
+
+ps-am:
+
+uninstall-am:
+
+.MAKE: all check install install-am install-exec install-strip
+
+.PHONY: CTAGS GTAGS TAGS all all-am am--depfiles check check-am clean \
+	clean-generic clean-libtool clean-noinstLIBRARIES \
+	cscopelist-am ctags ctags-am distclean distclean-compile \
+	distclean-generic distclean-libtool distclean-tags distdir dvi \
+	dvi-am html html-am info info-am install install-am \
+	install-data install-data-am install-dvi install-dvi-am \
+	install-exec install-exec-am install-html install-html-am \
+	install-info install-info-am install-man install-pdf \
+	install-pdf-am install-ps install-ps-am install-strip \
+	installcheck installcheck-am installdirs maintainer-clean \
+	maintainer-clean-generic mostlyclean mostlyclean-compile \
+	mostlyclean-generic mostlyclean-libtool pdf pdf-am ps ps-am \
+	tags tags-am uninstall uninstall-am
+
+.PRECIOUS: Makefile
+
+
+gimpmarshal.h: $(srcdir)/gimpmarshal.list
+	$(AM_V_GEN) $(GLIB_GENMARSHAL) --prefix=gimp_marshal $(srcdir)/gimpmarshal.list --header >> xgen-gmh \
+	&& (cmp -s xgen-gmh $(@F) || cp xgen-gmh $(@F)) \
+	&& rm -f xgen-gmh xgen-gmh~
+
+gimpmarshal.c: gimpmarshal.h
+	$(AM_V_GEN) $(GLIB_GENMARSHAL) --prefix=gimp_marshal $(srcdir)/gimpmarshal.list --header --body >> xgen-gmc \
+	&& cp xgen-gmc $(@F) \
+	&& rm -f xgen-gmc xgen-gmc~
+
+xgen-cec: $(srcdir)/core-enums.h $(GIMP_MKENUMS) Makefile.am
+	$(AM_V_GEN) $(GIMP_MKENUMS) \
+		--fhead "#include \"config.h\"\n#include <gio/gio.h>\n#include \"libgimpbase/gimpbase.h\"\n#include \"core-enums.h\"\n#include \"gimp-intl.h\"" \
+		--fprod "\n/* enumerations from \"@basename@\" */" \
+		--vhead "GType\n@enum_name@_get_type (void)\n{\n  static const G@Type@Value values[] =\n  {" \
+		--vprod "    { @VALUENAME@, \"@VALUENAME@\", \"@valuenick@\" }," \
+		--vtail "    { 0, NULL, NULL }\n  };\n" \
+		--dhead "  static const Gimp@Type@Desc descs[] =\n  {" \
+		--dprod "    { @VALUENAME@, @valuedesc@, @valuehelp@ },@if ('@valueabbrev@' ne 'NULL')@\n    /* Translators: this is an abbreviated version of @valueudesc@.\n       Keep it short. */\n    { @VALUENAME@, @valueabbrev@, NULL },@endif@" \
+		--dtail "    { 0, NULL, NULL }\n  };\n\n  static GType type = 0;\n\n  if (G_UNLIKELY (! type))\n    {\n      type = g_@type@_register_static (\"@EnumName@\", values);\n      gimp_type_set_translation_context (type, \"@enumnick@\");\n      gimp_@type@_set_value_descriptions (type, descs);\n    }\n\n  return type;\n}\n" \
+		$< > $@
+
+# copy the generated enum file back to the source directory only if it's
+# changed; otherwise, only update its timestamp, so that the recipe isn't
+# executed again on the next build, however, allow this to (harmlessly) fail,
+# to support building from a read-only source tree.
+$(srcdir)/core-enums.c: xgen-cec
+	$(AM_V_GEN) if ! cmp -s $< $@; then \
+		cp $< $@; \
+	else \
+		touch $@ 2> /dev/null \
+		|| true; \
+	fi
+
+# Tell versions [3.59,3.63) of GNU make to not export all variables.
+# Otherwise a system limit (for SysV at least) may be exceeded.
+.NOEXPORT:
diff --git a/app/core/core-enums.c b/app/core/core-enums.c
new file mode 100644
index 0000000..f8ecb14
--- /dev/null
+++ b/app/core/core-enums.c
@@ -0,0 +1,1316 @@
+
+/* Generated data (by gimp-mkenums) */
+
+#include "config.h"
+#include <gio/gio.h>
+#include "libgimpbase/gimpbase.h"
+#include "core-enums.h"
+#include "gimp-intl.h"
+
+/* enumerations from "core-enums.h" */
+GType
+gimp_align_reference_type_get_type (void)
+{
+  static const GEnumValue values[] =
+  {
+    { GIMP_ALIGN_REFERENCE_FIRST, "GIMP_ALIGN_REFERENCE_FIRST", "first" },
+    { GIMP_ALIGN_REFERENCE_IMAGE, "GIMP_ALIGN_REFERENCE_IMAGE", "image" },
+    { GIMP_ALIGN_REFERENCE_SELECTION, "GIMP_ALIGN_REFERENCE_SELECTION", "selection" },
+    { GIMP_ALIGN_REFERENCE_ACTIVE_LAYER, "GIMP_ALIGN_REFERENCE_ACTIVE_LAYER", "active-layer" },
+    { GIMP_ALIGN_REFERENCE_ACTIVE_CHANNEL, "GIMP_ALIGN_REFERENCE_ACTIVE_CHANNEL", "active-channel" },
+    { GIMP_ALIGN_REFERENCE_ACTIVE_PATH, "GIMP_ALIGN_REFERENCE_ACTIVE_PATH", "active-path" },
+    { 0, NULL, NULL }
+  };
+
+  static const GimpEnumDesc descs[] =
+  {
+    { GIMP_ALIGN_REFERENCE_FIRST, NC_("align-reference-type", "First item"), NULL },
+    { GIMP_ALIGN_REFERENCE_IMAGE, NC_("align-reference-type", "Image"), NULL },
+    { GIMP_ALIGN_REFERENCE_SELECTION, NC_("align-reference-type", "Selection"), NULL },
+    { GIMP_ALIGN_REFERENCE_ACTIVE_LAYER, NC_("align-reference-type", "Active layer"), NULL },
+    { GIMP_ALIGN_REFERENCE_ACTIVE_CHANNEL, NC_("align-reference-type", "Active channel"), NULL },
+    { GIMP_ALIGN_REFERENCE_ACTIVE_PATH, NC_("align-reference-type", "Active path"), NULL },
+    { 0, NULL, NULL }
+  };
+
+  static GType type = 0;
+
+  if (G_UNLIKELY (! type))
+    {
+      type = g_enum_register_static ("GimpAlignReferenceType", values);
+      gimp_type_set_translation_context (type, "align-reference-type");
+      gimp_enum_set_value_descriptions (type, descs);
+    }
+
+  return type;
+}
+
+GType
+gimp_alignment_type_get_type (void)
+{
+  static const GEnumValue values[] =
+  {
+    { GIMP_ALIGN_LEFT, "GIMP_ALIGN_LEFT", "align-left" },
+    { GIMP_ALIGN_HCENTER, "GIMP_ALIGN_HCENTER", "align-hcenter" },
+    { GIMP_ALIGN_RIGHT, "GIMP_ALIGN_RIGHT", "align-right" },
+    { GIMP_ALIGN_TOP, "GIMP_ALIGN_TOP", "align-top" },
+    { GIMP_ALIGN_VCENTER, "GIMP_ALIGN_VCENTER", "align-vcenter" },
+    { GIMP_ALIGN_BOTTOM, "GIMP_ALIGN_BOTTOM", "align-bottom" },
+    { GIMP_ARRANGE_LEFT, "GIMP_ARRANGE_LEFT", "arrange-left" },
+    { GIMP_ARRANGE_HCENTER, "GIMP_ARRANGE_HCENTER", "arrange-hcenter" },
+    { GIMP_ARRANGE_RIGHT, "GIMP_ARRANGE_RIGHT", "arrange-right" },
+    { GIMP_ARRANGE_TOP, "GIMP_ARRANGE_TOP", "arrange-top" },
+    { GIMP_ARRANGE_VCENTER, "GIMP_ARRANGE_VCENTER", "arrange-vcenter" },
+    { GIMP_ARRANGE_BOTTOM, "GIMP_ARRANGE_BOTTOM", "arrange-bottom" },
+    { GIMP_ARRANGE_HFILL, "GIMP_ARRANGE_HFILL", "arrange-hfill" },
+    { GIMP_ARRANGE_VFILL, "GIMP_ARRANGE_VFILL", "arrange-vfill" },
+    { 0, NULL, NULL }
+  };
+
+  static const GimpEnumDesc descs[] =
+  {
+    { GIMP_ALIGN_LEFT, "GIMP_ALIGN_LEFT", NULL },
+    { GIMP_ALIGN_HCENTER, "GIMP_ALIGN_HCENTER", NULL },
+    { GIMP_ALIGN_RIGHT, "GIMP_ALIGN_RIGHT", NULL },
+    { GIMP_ALIGN_TOP, "GIMP_ALIGN_TOP", NULL },
+    { GIMP_ALIGN_VCENTER, "GIMP_ALIGN_VCENTER", NULL },
+    { GIMP_ALIGN_BOTTOM, "GIMP_ALIGN_BOTTOM", NULL },
+    { GIMP_ARRANGE_LEFT, "GIMP_ARRANGE_LEFT", NULL },
+    { GIMP_ARRANGE_HCENTER, "GIMP_ARRANGE_HCENTER", NULL },
+    { GIMP_ARRANGE_RIGHT, "GIMP_ARRANGE_RIGHT", NULL },
+    { GIMP_ARRANGE_TOP, "GIMP_ARRANGE_TOP", NULL },
+    { GIMP_ARRANGE_VCENTER, "GIMP_ARRANGE_VCENTER", NULL },
+    { GIMP_ARRANGE_BOTTOM, "GIMP_ARRANGE_BOTTOM", NULL },
+    { GIMP_ARRANGE_HFILL, "GIMP_ARRANGE_HFILL", NULL },
+    { GIMP_ARRANGE_VFILL, "GIMP_ARRANGE_VFILL", NULL },
+    { 0, NULL, NULL }
+  };
+
+  static GType type = 0;
+
+  if (G_UNLIKELY (! type))
+    {
+      type = g_enum_register_static ("GimpAlignmentType", values);
+      gimp_type_set_translation_context (type, "alignment-type");
+      gimp_enum_set_value_descriptions (type, descs);
+    }
+
+  return type;
+}
+
+GType
+gimp_channel_border_style_get_type (void)
+{
+  static const GEnumValue values[] =
+  {
+    { GIMP_CHANNEL_BORDER_STYLE_HARD, "GIMP_CHANNEL_BORDER_STYLE_HARD", "hard" },
+    { GIMP_CHANNEL_BORDER_STYLE_SMOOTH, "GIMP_CHANNEL_BORDER_STYLE_SMOOTH", "smooth" },
+    { GIMP_CHANNEL_BORDER_STYLE_FEATHERED, "GIMP_CHANNEL_BORDER_STYLE_FEATHERED", "feathered" },
+    { 0, NULL, NULL }
+  };
+
+  static const GimpEnumDesc descs[] =
+  {
+    { GIMP_CHANNEL_BORDER_STYLE_HARD, NC_("channel-border-style", "Hard"), NULL },
+    { GIMP_CHANNEL_BORDER_STYLE_SMOOTH, NC_("channel-border-style", "Smooth"), NULL },
+    { GIMP_CHANNEL_BORDER_STYLE_FEATHERED, NC_("channel-border-style", "Feathered"), NULL },
+    { 0, NULL, NULL }
+  };
+
+  static GType type = 0;
+
+  if (G_UNLIKELY (! type))
+    {
+      type = g_enum_register_static ("GimpChannelBorderStyle", values);
+      gimp_type_set_translation_context (type, "channel-border-style");
+      gimp_enum_set_value_descriptions (type, descs);
+    }
+
+  return type;
+}
+
+GType
+gimp_color_pick_mode_get_type (void)
+{
+  static const GEnumValue values[] =
+  {
+    { GIMP_COLOR_PICK_MODE_PIXEL, "GIMP_COLOR_PICK_MODE_PIXEL", "pixel" },
+    { GIMP_COLOR_PICK_MODE_RGB_PERCENT, "GIMP_COLOR_PICK_MODE_RGB_PERCENT", "rgb-percent" },
+    { GIMP_COLOR_PICK_MODE_RGB_U8, "GIMP_COLOR_PICK_MODE_RGB_U8", "rgb-u8" },
+    { GIMP_COLOR_PICK_MODE_HSV, "GIMP_COLOR_PICK_MODE_HSV", "hsv" },
+    { GIMP_COLOR_PICK_MODE_LCH, "GIMP_COLOR_PICK_MODE_LCH", "lch" },
+    { GIMP_COLOR_PICK_MODE_LAB, "GIMP_COLOR_PICK_MODE_LAB", "lab" },
+    { GIMP_COLOR_PICK_MODE_CMYK, "GIMP_COLOR_PICK_MODE_CMYK", "cmyk" },
+    { GIMP_COLOR_PICK_MODE_XYY, "GIMP_COLOR_PICK_MODE_XYY", "xyy" },
+    { GIMP_COLOR_PICK_MODE_YUV, "GIMP_COLOR_PICK_MODE_YUV", "yuv" },
+    { 0, NULL, NULL }
+  };
+
+  static const GimpEnumDesc descs[] =
+  {
+    { GIMP_COLOR_PICK_MODE_PIXEL, NC_("color-pick-mode", "Pixel"), NULL },
+    { GIMP_COLOR_PICK_MODE_RGB_PERCENT, NC_("color-pick-mode", "RGB (%)"), NULL },
+    { GIMP_COLOR_PICK_MODE_RGB_U8, NC_("color-pick-mode", "RGB (0..255)"), NULL },
+    { GIMP_COLOR_PICK_MODE_HSV, NC_("color-pick-mode", "HSV"), NULL },
+    { GIMP_COLOR_PICK_MODE_LCH, NC_("color-pick-mode", "CIE LCh"), NULL },
+    { GIMP_COLOR_PICK_MODE_LAB, NC_("color-pick-mode", "CIE LAB"), NULL },
+    { GIMP_COLOR_PICK_MODE_CMYK, NC_("color-pick-mode", "CMYK"), NULL },
+    { GIMP_COLOR_PICK_MODE_XYY, NC_("color-pick-mode", "CIE xyY"), NULL },
+    { GIMP_COLOR_PICK_MODE_YUV, NC_("color-pick-mode", "CIE Yu'v'"), NULL },
+    { 0, NULL, NULL }
+  };
+
+  static GType type = 0;
+
+  if (G_UNLIKELY (! type))
+    {
+      type = g_enum_register_static ("GimpColorPickMode", values);
+      gimp_type_set_translation_context (type, "color-pick-mode");
+      gimp_enum_set_value_descriptions (type, descs);
+    }
+
+  return type;
+}
+
+GType
+gimp_color_profile_policy_get_type (void)
+{
+  static const GEnumValue values[] =
+  {
+    { GIMP_COLOR_PROFILE_POLICY_ASK, "GIMP_COLOR_PROFILE_POLICY_ASK", "ask" },
+    { GIMP_COLOR_PROFILE_POLICY_KEEP, "GIMP_COLOR_PROFILE_POLICY_KEEP", "keep" },
+    { GIMP_COLOR_PROFILE_POLICY_CONVERT, "GIMP_COLOR_PROFILE_POLICY_CONVERT", "convert" },
+    { 0, NULL, NULL }
+  };
+
+  static const GimpEnumDesc descs[] =
+  {
+    { GIMP_COLOR_PROFILE_POLICY_ASK, NC_("color-profile-policy", "Ask what to do"), NULL },
+    { GIMP_COLOR_PROFILE_POLICY_KEEP, NC_("color-profile-policy", "Keep embedded profile"), NULL },
+    { GIMP_COLOR_PROFILE_POLICY_CONVERT, NC_("color-profile-policy", "Convert to built-in sRGB or grayscale profile"), NULL },
+    { 0, NULL, NULL }
+  };
+
+  static GType type = 0;
+
+  if (G_UNLIKELY (! type))
+    {
+      type = g_enum_register_static ("GimpColorProfilePolicy", values);
+      gimp_type_set_translation_context (type, "color-profile-policy");
+      gimp_enum_set_value_descriptions (type, descs);
+    }
+
+  return type;
+}
+
+GType
+gimp_component_mask_get_type (void)
+{
+  static const GFlagsValue values[] =
+  {
+    { GIMP_COMPONENT_MASK_RED, "GIMP_COMPONENT_MASK_RED", "red" },
+    { GIMP_COMPONENT_MASK_GREEN, "GIMP_COMPONENT_MASK_GREEN", "green" },
+    { GIMP_COMPONENT_MASK_BLUE, "GIMP_COMPONENT_MASK_BLUE", "blue" },
+    { GIMP_COMPONENT_MASK_ALPHA, "GIMP_COMPONENT_MASK_ALPHA", "alpha" },
+    { GIMP_COMPONENT_MASK_ALL, "GIMP_COMPONENT_MASK_ALL", "all" },
+    { 0, NULL, NULL }
+  };
+
+  static const GimpFlagsDesc descs[] =
+  {
+    { GIMP_COMPONENT_MASK_RED, "GIMP_COMPONENT_MASK_RED", NULL },
+    { GIMP_COMPONENT_MASK_GREEN, "GIMP_COMPONENT_MASK_GREEN", NULL },
+    { GIMP_COMPONENT_MASK_BLUE, "GIMP_COMPONENT_MASK_BLUE", NULL },
+    { GIMP_COMPONENT_MASK_ALPHA, "GIMP_COMPONENT_MASK_ALPHA", NULL },
+    { GIMP_COMPONENT_MASK_ALL, "GIMP_COMPONENT_MASK_ALL", NULL },
+    { 0, NULL, NULL }
+  };
+
+  static GType type = 0;
+
+  if (G_UNLIKELY (! type))
+    {
+      type = g_flags_register_static ("GimpComponentMask", values);
+      gimp_type_set_translation_context (type, "component-mask");
+      gimp_flags_set_value_descriptions (type, descs);
+    }
+
+  return type;
+}
+
+GType
+gimp_container_policy_get_type (void)
+{
+  static const GEnumValue values[] =
+  {
+    { GIMP_CONTAINER_POLICY_STRONG, "GIMP_CONTAINER_POLICY_STRONG", "strong" },
+    { GIMP_CONTAINER_POLICY_WEAK, "GIMP_CONTAINER_POLICY_WEAK", "weak" },
+    { 0, NULL, NULL }
+  };
+
+  static const GimpEnumDesc descs[] =
+  {
+    { GIMP_CONTAINER_POLICY_STRONG, "GIMP_CONTAINER_POLICY_STRONG", NULL },
+    { GIMP_CONTAINER_POLICY_WEAK, "GIMP_CONTAINER_POLICY_WEAK", NULL },
+    { 0, NULL, NULL }
+  };
+
+  static GType type = 0;
+
+  if (G_UNLIKELY (! type))
+    {
+      type = g_enum_register_static ("GimpContainerPolicy", values);
+      gimp_type_set_translation_context (type, "container-policy");
+      gimp_enum_set_value_descriptions (type, descs);
+    }
+
+  return type;
+}
+
+GType
+gimp_convert_dither_type_get_type (void)
+{
+  static const GEnumValue values[] =
+  {
+    { GIMP_CONVERT_DITHER_NONE, "GIMP_CONVERT_DITHER_NONE", "none" },
+    { GIMP_CONVERT_DITHER_FS, "GIMP_CONVERT_DITHER_FS", "fs" },
+    { GIMP_CONVERT_DITHER_FS_LOWBLEED, "GIMP_CONVERT_DITHER_FS_LOWBLEED", "fs-lowbleed" },
+    { GIMP_CONVERT_DITHER_FIXED, "GIMP_CONVERT_DITHER_FIXED", "fixed" },
+    { 0, NULL, NULL }
+  };
+
+  static const GimpEnumDesc descs[] =
+  {
+    { GIMP_CONVERT_DITHER_NONE, NC_("convert-dither-type", "None"), NULL },
+    { GIMP_CONVERT_DITHER_FS, NC_("convert-dither-type", "Floyd-Steinberg (normal)"), NULL },
+    { GIMP_CONVERT_DITHER_FS_LOWBLEED, NC_("convert-dither-type", "Floyd-Steinberg (reduced color bleeding)"), NULL },
+    { GIMP_CONVERT_DITHER_FIXED, NC_("convert-dither-type", "Positioned"), NULL },
+    { 0, NULL, NULL }
+  };
+
+  static GType type = 0;
+
+  if (G_UNLIKELY (! type))
+    {
+      type = g_enum_register_static ("GimpConvertDitherType", values);
+      gimp_type_set_translation_context (type, "convert-dither-type");
+      gimp_enum_set_value_descriptions (type, descs);
+    }
+
+  return type;
+}
+
+GType
+gimp_convolution_type_get_type (void)
+{
+  static const GEnumValue values[] =
+  {
+    { GIMP_NORMAL_CONVOL, "GIMP_NORMAL_CONVOL", "normal-convol" },
+    { GIMP_ABSOLUTE_CONVOL, "GIMP_ABSOLUTE_CONVOL", "absolute-convol" },
+    { GIMP_NEGATIVE_CONVOL, "GIMP_NEGATIVE_CONVOL", "negative-convol" },
+    { 0, NULL, NULL }
+  };
+
+  static const GimpEnumDesc descs[] =
+  {
+    { GIMP_NORMAL_CONVOL, "GIMP_NORMAL_CONVOL", NULL },
+    { GIMP_ABSOLUTE_CONVOL, "GIMP_ABSOLUTE_CONVOL", NULL },
+    { GIMP_NEGATIVE_CONVOL, "GIMP_NEGATIVE_CONVOL", NULL },
+    { 0, NULL, NULL }
+  };
+
+  static GType type = 0;
+
+  if (G_UNLIKELY (! type))
+    {
+      type = g_enum_register_static ("GimpConvolutionType", values);
+      gimp_type_set_translation_context (type, "convolution-type");
+      gimp_enum_set_value_descriptions (type, descs);
+    }
+
+  return type;
+}
+
+GType
+gimp_curve_point_type_get_type (void)
+{
+  static const GEnumValue values[] =
+  {
+    { GIMP_CURVE_POINT_SMOOTH, "GIMP_CURVE_POINT_SMOOTH", "smooth" },
+    { GIMP_CURVE_POINT_CORNER, "GIMP_CURVE_POINT_CORNER", "corner" },
+    { 0, NULL, NULL }
+  };
+
+  static const GimpEnumDesc descs[] =
+  {
+    { GIMP_CURVE_POINT_SMOOTH, NC_("curve-point-type", "Smooth"), NULL },
+    { GIMP_CURVE_POINT_CORNER, NC_("curve-point-type", "Corner"), NULL },
+    { 0, NULL, NULL }
+  };
+
+  static GType type = 0;
+
+  if (G_UNLIKELY (! type))
+    {
+      type = g_enum_register_static ("GimpCurvePointType", values);
+      gimp_type_set_translation_context (type, "curve-point-type");
+      gimp_enum_set_value_descriptions (type, descs);
+    }
+
+  return type;
+}
+
+GType
+gimp_curve_type_get_type (void)
+{
+  static const GEnumValue values[] =
+  {
+    { GIMP_CURVE_SMOOTH, "GIMP_CURVE_SMOOTH", "smooth" },
+    { GIMP_CURVE_FREE, "GIMP_CURVE_FREE", "free" },
+    { 0, NULL, NULL }
+  };
+
+  static const GimpEnumDesc descs[] =
+  {
+    { GIMP_CURVE_SMOOTH, NC_("curve-type", "Smooth"), NULL },
+    { GIMP_CURVE_FREE, NC_("curve-type", "Freehand"), NULL },
+    { 0, NULL, NULL }
+  };
+
+  static GType type = 0;
+
+  if (G_UNLIKELY (! type))
+    {
+      type = g_enum_register_static ("GimpCurveType", values);
+      gimp_type_set_translation_context (type, "curve-type");
+      gimp_enum_set_value_descriptions (type, descs);
+    }
+
+  return type;
+}
+
+GType
+gimp_dash_preset_get_type (void)
+{
+  static const GEnumValue values[] =
+  {
+    { GIMP_DASH_CUSTOM, "GIMP_DASH_CUSTOM", "custom" },
+    { GIMP_DASH_LINE, "GIMP_DASH_LINE", "line" },
+    { GIMP_DASH_LONG_DASH, "GIMP_DASH_LONG_DASH", "long-dash" },
+    { GIMP_DASH_MEDIUM_DASH, "GIMP_DASH_MEDIUM_DASH", "medium-dash" },
+    { GIMP_DASH_SHORT_DASH, "GIMP_DASH_SHORT_DASH", "short-dash" },
+    { GIMP_DASH_SPARSE_DOTS, "GIMP_DASH_SPARSE_DOTS", "sparse-dots" },
+    { GIMP_DASH_NORMAL_DOTS, "GIMP_DASH_NORMAL_DOTS", "normal-dots" },
+    { GIMP_DASH_DENSE_DOTS, "GIMP_DASH_DENSE_DOTS", "dense-dots" },
+    { GIMP_DASH_STIPPLES, "GIMP_DASH_STIPPLES", "stipples" },
+    { GIMP_DASH_DASH_DOT, "GIMP_DASH_DASH_DOT", "dash-dot" },
+    { GIMP_DASH_DASH_DOT_DOT, "GIMP_DASH_DASH_DOT_DOT", "dash-dot-dot" },
+    { 0, NULL, NULL }
+  };
+
+  static const GimpEnumDesc descs[] =
+  {
+    { GIMP_DASH_CUSTOM, NC_("dash-preset", "Custom"), NULL },
+    { GIMP_DASH_LINE, NC_("dash-preset", "Line"), NULL },
+    { GIMP_DASH_LONG_DASH, NC_("dash-preset", "Long dashes"), NULL },
+    { GIMP_DASH_MEDIUM_DASH, NC_("dash-preset", "Medium dashes"), NULL },
+    { GIMP_DASH_SHORT_DASH, NC_("dash-preset", "Short dashes"), NULL },
+    { GIMP_DASH_SPARSE_DOTS, NC_("dash-preset", "Sparse dots"), NULL },
+    { GIMP_DASH_NORMAL_DOTS, NC_("dash-preset", "Normal dots"), NULL },
+    { GIMP_DASH_DENSE_DOTS, NC_("dash-preset", "Dense dots"), NULL },
+    { GIMP_DASH_STIPPLES, NC_("dash-preset", "Stipples"), NULL },
+    { GIMP_DASH_DASH_DOT, NC_("dash-preset", "Dash, dot"), NULL },
+    { GIMP_DASH_DASH_DOT_DOT, NC_("dash-preset", "Dash, dot, dot"), NULL },
+    { 0, NULL, NULL }
+  };
+
+  static GType type = 0;
+
+  if (G_UNLIKELY (! type))
+    {
+      type = g_enum_register_static ("GimpDashPreset", values);
+      gimp_type_set_translation_context (type, "dash-preset");
+      gimp_enum_set_value_descriptions (type, descs);
+    }
+
+  return type;
+}
+
+GType
+gimp_debug_policy_get_type (void)
+{
+  static const GEnumValue values[] =
+  {
+    { GIMP_DEBUG_POLICY_WARNING, "GIMP_DEBUG_POLICY_WARNING", "warning" },
+    { GIMP_DEBUG_POLICY_CRITICAL, "GIMP_DEBUG_POLICY_CRITICAL", "critical" },
+    { GIMP_DEBUG_POLICY_FATAL, "GIMP_DEBUG_POLICY_FATAL", "fatal" },
+    { GIMP_DEBUG_POLICY_NEVER, "GIMP_DEBUG_POLICY_NEVER", "never" },
+    { 0, NULL, NULL }
+  };
+
+  static const GimpEnumDesc descs[] =
+  {
+    { GIMP_DEBUG_POLICY_WARNING, NC_("debug-policy", "Debug warnings, critical errors and crashes"), NULL },
+    { GIMP_DEBUG_POLICY_CRITICAL, NC_("debug-policy", "Debug critical errors and crashes"), NULL },
+    { GIMP_DEBUG_POLICY_FATAL, NC_("debug-policy", "Debug crashes only"), NULL },
+    { GIMP_DEBUG_POLICY_NEVER, NC_("debug-policy", "Never debug GIMP"), NULL },
+    { 0, NULL, NULL }
+  };
+
+  static GType type = 0;
+
+  if (G_UNLIKELY (! type))
+    {
+      type = g_enum_register_static ("GimpDebugPolicy", values);
+      gimp_type_set_translation_context (type, "debug-policy");
+      gimp_enum_set_value_descriptions (type, descs);
+    }
+
+  return type;
+}
+
+GType
+gimp_dirty_mask_get_type (void)
+{
+  static const GFlagsValue values[] =
+  {
+    { GIMP_DIRTY_NONE, "GIMP_DIRTY_NONE", "none" },
+    { GIMP_DIRTY_IMAGE, "GIMP_DIRTY_IMAGE", "image" },
+    { GIMP_DIRTY_IMAGE_SIZE, "GIMP_DIRTY_IMAGE_SIZE", "image-size" },
+    { GIMP_DIRTY_IMAGE_META, "GIMP_DIRTY_IMAGE_META", "image-meta" },
+    { GIMP_DIRTY_IMAGE_STRUCTURE, "GIMP_DIRTY_IMAGE_STRUCTURE", "image-structure" },
+    { GIMP_DIRTY_ITEM, "GIMP_DIRTY_ITEM", "item" },
+    { GIMP_DIRTY_ITEM_META, "GIMP_DIRTY_ITEM_META", "item-meta" },
+    { GIMP_DIRTY_DRAWABLE, "GIMP_DIRTY_DRAWABLE", "drawable" },
+    { GIMP_DIRTY_VECTORS, "GIMP_DIRTY_VECTORS", "vectors" },
+    { GIMP_DIRTY_SELECTION, "GIMP_DIRTY_SELECTION", "selection" },
+    { GIMP_DIRTY_ACTIVE_DRAWABLE, "GIMP_DIRTY_ACTIVE_DRAWABLE", "active-drawable" },
+    { GIMP_DIRTY_ALL, "GIMP_DIRTY_ALL", "all" },
+    { 0, NULL, NULL }
+  };
+
+  static const GimpFlagsDesc descs[] =
+  {
+    { GIMP_DIRTY_NONE, "GIMP_DIRTY_NONE", NULL },
+    { GIMP_DIRTY_IMAGE, "GIMP_DIRTY_IMAGE", NULL },
+    { GIMP_DIRTY_IMAGE_SIZE, "GIMP_DIRTY_IMAGE_SIZE", NULL },
+    { GIMP_DIRTY_IMAGE_META, "GIMP_DIRTY_IMAGE_META", NULL },
+    { GIMP_DIRTY_IMAGE_STRUCTURE, "GIMP_DIRTY_IMAGE_STRUCTURE", NULL },
+    { GIMP_DIRTY_ITEM, "GIMP_DIRTY_ITEM", NULL },
+    { GIMP_DIRTY_ITEM_META, "GIMP_DIRTY_ITEM_META", NULL },
+    { GIMP_DIRTY_DRAWABLE, "GIMP_DIRTY_DRAWABLE", NULL },
+    { GIMP_DIRTY_VECTORS, "GIMP_DIRTY_VECTORS", NULL },
+    { GIMP_DIRTY_SELECTION, "GIMP_DIRTY_SELECTION", NULL },
+    { GIMP_DIRTY_ACTIVE_DRAWABLE, "GIMP_DIRTY_ACTIVE_DRAWABLE", NULL },
+    { GIMP_DIRTY_ALL, "GIMP_DIRTY_ALL", NULL },
+    { 0, NULL, NULL }
+  };
+
+  static GType type = 0;
+
+  if (G_UNLIKELY (! type))
+    {
+      type = g_flags_register_static ("GimpDirtyMask", values);
+      gimp_type_set_translation_context (type, "dirty-mask");
+      gimp_flags_set_value_descriptions (type, descs);
+    }
+
+  return type;
+}
+
+GType
+gimp_dynamics_output_type_get_type (void)
+{
+  static const GEnumValue values[] =
+  {
+    { GIMP_DYNAMICS_OUTPUT_OPACITY, "GIMP_DYNAMICS_OUTPUT_OPACITY", "opacity" },
+    { GIMP_DYNAMICS_OUTPUT_SIZE, "GIMP_DYNAMICS_OUTPUT_SIZE", "size" },
+    { GIMP_DYNAMICS_OUTPUT_ANGLE, "GIMP_DYNAMICS_OUTPUT_ANGLE", "angle" },
+    { GIMP_DYNAMICS_OUTPUT_COLOR, "GIMP_DYNAMICS_OUTPUT_COLOR", "color" },
+    { GIMP_DYNAMICS_OUTPUT_HARDNESS, "GIMP_DYNAMICS_OUTPUT_HARDNESS", "hardness" },
+    { GIMP_DYNAMICS_OUTPUT_FORCE, "GIMP_DYNAMICS_OUTPUT_FORCE", "force" },
+    { GIMP_DYNAMICS_OUTPUT_ASPECT_RATIO, "GIMP_DYNAMICS_OUTPUT_ASPECT_RATIO", "aspect-ratio" },
+    { GIMP_DYNAMICS_OUTPUT_SPACING, "GIMP_DYNAMICS_OUTPUT_SPACING", "spacing" },
+    { GIMP_DYNAMICS_OUTPUT_RATE, "GIMP_DYNAMICS_OUTPUT_RATE", "rate" },
+    { GIMP_DYNAMICS_OUTPUT_FLOW, "GIMP_DYNAMICS_OUTPUT_FLOW", "flow" },
+    { GIMP_DYNAMICS_OUTPUT_JITTER, "GIMP_DYNAMICS_OUTPUT_JITTER", "jitter" },
+    { 0, NULL, NULL }
+  };
+
+  static const GimpEnumDesc descs[] =
+  {
+    { GIMP_DYNAMICS_OUTPUT_OPACITY, NC_("dynamics-output-type", "Opacity"), NULL },
+    { GIMP_DYNAMICS_OUTPUT_SIZE, NC_("dynamics-output-type", "Size"), NULL },
+    { GIMP_DYNAMICS_OUTPUT_ANGLE, NC_("dynamics-output-type", "Angle"), NULL },
+    { GIMP_DYNAMICS_OUTPUT_COLOR, NC_("dynamics-output-type", "Color"), NULL },
+    { GIMP_DYNAMICS_OUTPUT_HARDNESS, NC_("dynamics-output-type", "Hardness"), NULL },
+    { GIMP_DYNAMICS_OUTPUT_FORCE, NC_("dynamics-output-type", "Force"), NULL },
+    { GIMP_DYNAMICS_OUTPUT_ASPECT_RATIO, NC_("dynamics-output-type", "Aspect ratio"), NULL },
+    { GIMP_DYNAMICS_OUTPUT_SPACING, NC_("dynamics-output-type", "Spacing"), NULL },
+    { GIMP_DYNAMICS_OUTPUT_RATE, NC_("dynamics-output-type", "Rate"), NULL },
+    { GIMP_DYNAMICS_OUTPUT_FLOW, NC_("dynamics-output-type", "Flow"), NULL },
+    { GIMP_DYNAMICS_OUTPUT_JITTER, NC_("dynamics-output-type", "Jitter"), NULL },
+    { 0, NULL, NULL }
+  };
+
+  static GType type = 0;
+
+  if (G_UNLIKELY (! type))
+    {
+      type = g_enum_register_static ("GimpDynamicsOutputType", values);
+      gimp_type_set_translation_context (type, "dynamics-output-type");
+      gimp_enum_set_value_descriptions (type, descs);
+    }
+
+  return type;
+}
+
+GType
+gimp_fill_style_get_type (void)
+{
+  static const GEnumValue values[] =
+  {
+    { GIMP_FILL_STYLE_SOLID, "GIMP_FILL_STYLE_SOLID", "solid" },
+    { GIMP_FILL_STYLE_PATTERN, "GIMP_FILL_STYLE_PATTERN", "pattern" },
+    { 0, NULL, NULL }
+  };
+
+  static const GimpEnumDesc descs[] =
+  {
+    { GIMP_FILL_STYLE_SOLID, NC_("fill-style", "Solid color"), NULL },
+    { GIMP_FILL_STYLE_PATTERN, NC_("fill-style", "Pattern"), NULL },
+    { 0, NULL, NULL }
+  };
+
+  static GType type = 0;
+
+  if (G_UNLIKELY (! type))
+    {
+      type = g_enum_register_static ("GimpFillStyle", values);
+      gimp_type_set_translation_context (type, "fill-style");
+      gimp_enum_set_value_descriptions (type, descs);
+    }
+
+  return type;
+}
+
+GType
+gimp_filter_region_get_type (void)
+{
+  static const GEnumValue values[] =
+  {
+    { GIMP_FILTER_REGION_SELECTION, "GIMP_FILTER_REGION_SELECTION", "selection" },
+    { GIMP_FILTER_REGION_DRAWABLE, "GIMP_FILTER_REGION_DRAWABLE", "drawable" },
+    { 0, NULL, NULL }
+  };
+
+  static const GimpEnumDesc descs[] =
+  {
+    { GIMP_FILTER_REGION_SELECTION, NC_("filter-region", "Use the selection as input"), NULL },
+    { GIMP_FILTER_REGION_DRAWABLE, NC_("filter-region", "Use the entire layer as input"), NULL },
+    { 0, NULL, NULL }
+  };
+
+  static GType type = 0;
+
+  if (G_UNLIKELY (! type))
+    {
+      type = g_enum_register_static ("GimpFilterRegion", values);
+      gimp_type_set_translation_context (type, "filter-region");
+      gimp_enum_set_value_descriptions (type, descs);
+    }
+
+  return type;
+}
+
+GType
+gimp_gradient_color_get_type (void)
+{
+  static const GEnumValue values[] =
+  {
+    { GIMP_GRADIENT_COLOR_FIXED, "GIMP_GRADIENT_COLOR_FIXED", "fixed" },
+    { GIMP_GRADIENT_COLOR_FOREGROUND, "GIMP_GRADIENT_COLOR_FOREGROUND", "foreground" },
+    { GIMP_GRADIENT_COLOR_FOREGROUND_TRANSPARENT, "GIMP_GRADIENT_COLOR_FOREGROUND_TRANSPARENT", "foreground-transparent" },
+    { GIMP_GRADIENT_COLOR_BACKGROUND, "GIMP_GRADIENT_COLOR_BACKGROUND", "background" },
+    { GIMP_GRADIENT_COLOR_BACKGROUND_TRANSPARENT, "GIMP_GRADIENT_COLOR_BACKGROUND_TRANSPARENT", "background-transparent" },
+    { 0, NULL, NULL }
+  };
+
+  static const GimpEnumDesc descs[] =
+  {
+    { GIMP_GRADIENT_COLOR_FIXED, NC_("gradient-color", "Fixed"), NULL },
+    { GIMP_GRADIENT_COLOR_FOREGROUND, NC_("gradient-color", "Foreground color"), NULL },
+    /* Translators: this is an abbreviated version of "Foreground color".
+       Keep it short. */
+    { GIMP_GRADIENT_COLOR_FOREGROUND, NC_("gradient-color", "FG"), NULL },
+    { GIMP_GRADIENT_COLOR_FOREGROUND_TRANSPARENT, NC_("gradient-color", "Foreground color (transparent)"), NULL },
+    /* Translators: this is an abbreviated version of "Foreground color (transparent)".
+       Keep it short. */
+    { GIMP_GRADIENT_COLOR_FOREGROUND_TRANSPARENT, NC_("gradient-color", "FG (t)"), NULL },
+    { GIMP_GRADIENT_COLOR_BACKGROUND, NC_("gradient-color", "Background color"), NULL },
+    /* Translators: this is an abbreviated version of "Background color".
+       Keep it short. */
+    { GIMP_GRADIENT_COLOR_BACKGROUND, NC_("gradient-color", "BG"), NULL },
+    { GIMP_GRADIENT_COLOR_BACKGROUND_TRANSPARENT, NC_("gradient-color", "Background color (transparent)"), NULL },
+    /* Translators: this is an abbreviated version of "Background color (transparent)".
+       Keep it short. */
+    { GIMP_GRADIENT_COLOR_BACKGROUND_TRANSPARENT, NC_("gradient-color", "BG (t)"), NULL },
+    { 0, NULL, NULL }
+  };
+
+  static GType type = 0;
+
+  if (G_UNLIKELY (! type))
+    {
+      type = g_enum_register_static ("GimpGradientColor", values);
+      gimp_type_set_translation_context (type, "gradient-color");
+      gimp_enum_set_value_descriptions (type, descs);
+    }
+
+  return type;
+}
+
+GType
+gimp_gravity_type_get_type (void)
+{
+  static const GEnumValue values[] =
+  {
+    { GIMP_GRAVITY_NONE, "GIMP_GRAVITY_NONE", "none" },
+    { GIMP_GRAVITY_NORTH_WEST, "GIMP_GRAVITY_NORTH_WEST", "north-west" },
+    { GIMP_GRAVITY_NORTH, "GIMP_GRAVITY_NORTH", "north" },
+    { GIMP_GRAVITY_NORTH_EAST, "GIMP_GRAVITY_NORTH_EAST", "north-east" },
+    { GIMP_GRAVITY_WEST, "GIMP_GRAVITY_WEST", "west" },
+    { GIMP_GRAVITY_CENTER, "GIMP_GRAVITY_CENTER", "center" },
+    { GIMP_GRAVITY_EAST, "GIMP_GRAVITY_EAST", "east" },
+    { GIMP_GRAVITY_SOUTH_WEST, "GIMP_GRAVITY_SOUTH_WEST", "south-west" },
+    { GIMP_GRAVITY_SOUTH, "GIMP_GRAVITY_SOUTH", "south" },
+    { GIMP_GRAVITY_SOUTH_EAST, "GIMP_GRAVITY_SOUTH_EAST", "south-east" },
+    { 0, NULL, NULL }
+  };
+
+  static const GimpEnumDesc descs[] =
+  {
+    { GIMP_GRAVITY_NONE, "GIMP_GRAVITY_NONE", NULL },
+    { GIMP_GRAVITY_NORTH_WEST, "GIMP_GRAVITY_NORTH_WEST", NULL },
+    { GIMP_GRAVITY_NORTH, "GIMP_GRAVITY_NORTH", NULL },
+    { GIMP_GRAVITY_NORTH_EAST, "GIMP_GRAVITY_NORTH_EAST", NULL },
+    { GIMP_GRAVITY_WEST, "GIMP_GRAVITY_WEST", NULL },
+    { GIMP_GRAVITY_CENTER, "GIMP_GRAVITY_CENTER", NULL },
+    { GIMP_GRAVITY_EAST, "GIMP_GRAVITY_EAST", NULL },
+    { GIMP_GRAVITY_SOUTH_WEST, "GIMP_GRAVITY_SOUTH_WEST", NULL },
+    { GIMP_GRAVITY_SOUTH, "GIMP_GRAVITY_SOUTH", NULL },
+    { GIMP_GRAVITY_SOUTH_EAST, "GIMP_GRAVITY_SOUTH_EAST", NULL },
+    { 0, NULL, NULL }
+  };
+
+  static GType type = 0;
+
+  if (G_UNLIKELY (! type))
+    {
+      type = g_enum_register_static ("GimpGravityType", values);
+      gimp_type_set_translation_context (type, "gravity-type");
+      gimp_enum_set_value_descriptions (type, descs);
+    }
+
+  return type;
+}
+
+GType
+gimp_guide_style_get_type (void)
+{
+  static const GEnumValue values[] =
+  {
+    { GIMP_GUIDE_STYLE_NONE, "GIMP_GUIDE_STYLE_NONE", "none" },
+    { GIMP_GUIDE_STYLE_NORMAL, "GIMP_GUIDE_STYLE_NORMAL", "normal" },
+    { GIMP_GUIDE_STYLE_MIRROR, "GIMP_GUIDE_STYLE_MIRROR", "mirror" },
+    { GIMP_GUIDE_STYLE_MANDALA, "GIMP_GUIDE_STYLE_MANDALA", "mandala" },
+    { GIMP_GUIDE_STYLE_SPLIT_VIEW, "GIMP_GUIDE_STYLE_SPLIT_VIEW", "split-view" },
+    { 0, NULL, NULL }
+  };
+
+  static const GimpEnumDesc descs[] =
+  {
+    { GIMP_GUIDE_STYLE_NONE, "GIMP_GUIDE_STYLE_NONE", NULL },
+    { GIMP_GUIDE_STYLE_NORMAL, "GIMP_GUIDE_STYLE_NORMAL", NULL },
+    { GIMP_GUIDE_STYLE_MIRROR, "GIMP_GUIDE_STYLE_MIRROR", NULL },
+    { GIMP_GUIDE_STYLE_MANDALA, "GIMP_GUIDE_STYLE_MANDALA", NULL },
+    { GIMP_GUIDE_STYLE_SPLIT_VIEW, "GIMP_GUIDE_STYLE_SPLIT_VIEW", NULL },
+    { 0, NULL, NULL }
+  };
+
+  static GType type = 0;
+
+  if (G_UNLIKELY (! type))
+    {
+      type = g_enum_register_static ("GimpGuideStyle", values);
+      gimp_type_set_translation_context (type, "guide-style");
+      gimp_enum_set_value_descriptions (type, descs);
+    }
+
+  return type;
+}
+
+GType
+gimp_histogram_channel_get_type (void)
+{
+  static const GEnumValue values[] =
+  {
+    { GIMP_HISTOGRAM_VALUE, "GIMP_HISTOGRAM_VALUE", "value" },
+    { GIMP_HISTOGRAM_RED, "GIMP_HISTOGRAM_RED", "red" },
+    { GIMP_HISTOGRAM_GREEN, "GIMP_HISTOGRAM_GREEN", "green" },
+    { GIMP_HISTOGRAM_BLUE, "GIMP_HISTOGRAM_BLUE", "blue" },
+    { GIMP_HISTOGRAM_ALPHA, "GIMP_HISTOGRAM_ALPHA", "alpha" },
+    { GIMP_HISTOGRAM_LUMINANCE, "GIMP_HISTOGRAM_LUMINANCE", "luminance" },
+    { GIMP_HISTOGRAM_RGB, "GIMP_HISTOGRAM_RGB", "rgb" },
+    { 0, NULL, NULL }
+  };
+
+  static const GimpEnumDesc descs[] =
+  {
+    { GIMP_HISTOGRAM_VALUE, NC_("histogram-channel", "Value"), NULL },
+    { GIMP_HISTOGRAM_RED, NC_("histogram-channel", "Red"), NULL },
+    { GIMP_HISTOGRAM_GREEN, NC_("histogram-channel", "Green"), NULL },
+    { GIMP_HISTOGRAM_BLUE, NC_("histogram-channel", "Blue"), NULL },
+    { GIMP_HISTOGRAM_ALPHA, NC_("histogram-channel", "Alpha"), NULL },
+    { GIMP_HISTOGRAM_LUMINANCE, NC_("histogram-channel", "Luminance"), NULL },
+    { GIMP_HISTOGRAM_RGB, NC_("histogram-channel", "RGB"), NULL },
+    { 0, NULL, NULL }
+  };
+
+  static GType type = 0;
+
+  if (G_UNLIKELY (! type))
+    {
+      type = g_enum_register_static ("GimpHistogramChannel", values);
+      gimp_type_set_translation_context (type, "histogram-channel");
+      gimp_enum_set_value_descriptions (type, descs);
+    }
+
+  return type;
+}
+
+GType
+gimp_item_set_get_type (void)
+{
+  static const GEnumValue values[] =
+  {
+    { GIMP_ITEM_SET_NONE, "GIMP_ITEM_SET_NONE", "none" },
+    { GIMP_ITEM_SET_ALL, "GIMP_ITEM_SET_ALL", "all" },
+    { GIMP_ITEM_SET_IMAGE_SIZED, "GIMP_ITEM_SET_IMAGE_SIZED", "image-sized" },
+    { GIMP_ITEM_SET_VISIBLE, "GIMP_ITEM_SET_VISIBLE", "visible" },
+    { GIMP_ITEM_SET_LINKED, "GIMP_ITEM_SET_LINKED", "linked" },
+    { 0, NULL, NULL }
+  };
+
+  static const GimpEnumDesc descs[] =
+  {
+    { GIMP_ITEM_SET_NONE, NC_("item-set", "None"), NULL },
+    { GIMP_ITEM_SET_ALL, NC_("item-set", "All layers"), NULL },
+    { GIMP_ITEM_SET_IMAGE_SIZED, NC_("item-set", "Image-sized layers"), NULL },
+    { GIMP_ITEM_SET_VISIBLE, NC_("item-set", "All visible layers"), NULL },
+    { GIMP_ITEM_SET_LINKED, NC_("item-set", "All linked layers"), NULL },
+    { 0, NULL, NULL }
+  };
+
+  static GType type = 0;
+
+  if (G_UNLIKELY (! type))
+    {
+      type = g_enum_register_static ("GimpItemSet", values);
+      gimp_type_set_translation_context (type, "item-set");
+      gimp_enum_set_value_descriptions (type, descs);
+    }
+
+  return type;
+}
+
+GType
+gimp_matting_engine_get_type (void)
+{
+  static const GEnumValue values[] =
+  {
+    { GIMP_MATTING_ENGINE_GLOBAL, "GIMP_MATTING_ENGINE_GLOBAL", "global" },
+    { GIMP_MATTING_ENGINE_LEVIN, "GIMP_MATTING_ENGINE_LEVIN", "levin" },
+    { 0, NULL, NULL }
+  };
+
+  static const GimpEnumDesc descs[] =
+  {
+    { GIMP_MATTING_ENGINE_GLOBAL, NC_("matting-engine", "Matting Global"), NULL },
+    { GIMP_MATTING_ENGINE_LEVIN, NC_("matting-engine", "Matting Levin"), NULL },
+    { 0, NULL, NULL }
+  };
+
+  static GType type = 0;
+
+  if (G_UNLIKELY (! type))
+    {
+      type = g_enum_register_static ("GimpMattingEngine", values);
+      gimp_type_set_translation_context (type, "matting-engine");
+      gimp_enum_set_value_descriptions (type, descs);
+    }
+
+  return type;
+}
+
+GType
+gimp_message_severity_get_type (void)
+{
+  static const GEnumValue values[] =
+  {
+    { GIMP_MESSAGE_INFO, "GIMP_MESSAGE_INFO", "info" },
+    { GIMP_MESSAGE_WARNING, "GIMP_MESSAGE_WARNING", "warning" },
+    { GIMP_MESSAGE_ERROR, "GIMP_MESSAGE_ERROR", "error" },
+    { GIMP_MESSAGE_BUG_WARNING, "GIMP_MESSAGE_BUG_WARNING", "bug-warning" },
+    { GIMP_MESSAGE_BUG_CRITICAL, "GIMP_MESSAGE_BUG_CRITICAL", "bug-critical" },
+    { 0, NULL, NULL }
+  };
+
+  static const GimpEnumDesc descs[] =
+  {
+    { GIMP_MESSAGE_INFO, NC_("message-severity", "Message"), NULL },
+    { GIMP_MESSAGE_WARNING, NC_("message-severity", "Warning"), NULL },
+    { GIMP_MESSAGE_ERROR, NC_("message-severity", "Error"), NULL },
+    { GIMP_MESSAGE_BUG_WARNING, NC_("message-severity", "WARNING"), NULL },
+    { GIMP_MESSAGE_BUG_CRITICAL, NC_("message-severity", "CRITICAL"), NULL },
+    { 0, NULL, NULL }
+  };
+
+  static GType type = 0;
+
+  if (G_UNLIKELY (! type))
+    {
+      type = g_enum_register_static ("GimpMessageSeverity", values);
+      gimp_type_set_translation_context (type, "message-severity");
+      gimp_enum_set_value_descriptions (type, descs);
+    }
+
+  return type;
+}
+
+GType
+gimp_paste_type_get_type (void)
+{
+  static const GEnumValue values[] =
+  {
+    { GIMP_PASTE_TYPE_FLOATING, "GIMP_PASTE_TYPE_FLOATING", "floating" },
+    { GIMP_PASTE_TYPE_FLOATING_IN_PLACE, "GIMP_PASTE_TYPE_FLOATING_IN_PLACE", "floating-in-place" },
+    { GIMP_PASTE_TYPE_FLOATING_INTO, "GIMP_PASTE_TYPE_FLOATING_INTO", "floating-into" },
+    { GIMP_PASTE_TYPE_FLOATING_INTO_IN_PLACE, "GIMP_PASTE_TYPE_FLOATING_INTO_IN_PLACE", "floating-into-in-place" },
+    { GIMP_PASTE_TYPE_NEW_LAYER, "GIMP_PASTE_TYPE_NEW_LAYER", "new-layer" },
+    { GIMP_PASTE_TYPE_NEW_LAYER_IN_PLACE, "GIMP_PASTE_TYPE_NEW_LAYER_IN_PLACE", "new-layer-in-place" },
+    { 0, NULL, NULL }
+  };
+
+  static const GimpEnumDesc descs[] =
+  {
+    { GIMP_PASTE_TYPE_FLOATING, "GIMP_PASTE_TYPE_FLOATING", NULL },
+    { GIMP_PASTE_TYPE_FLOATING_IN_PLACE, "GIMP_PASTE_TYPE_FLOATING_IN_PLACE", NULL },
+    { GIMP_PASTE_TYPE_FLOATING_INTO, "GIMP_PASTE_TYPE_FLOATING_INTO", NULL },
+    { GIMP_PASTE_TYPE_FLOATING_INTO_IN_PLACE, "GIMP_PASTE_TYPE_FLOATING_INTO_IN_PLACE", NULL },
+    { GIMP_PASTE_TYPE_NEW_LAYER, "GIMP_PASTE_TYPE_NEW_LAYER", NULL },
+    { GIMP_PASTE_TYPE_NEW_LAYER_IN_PLACE, "GIMP_PASTE_TYPE_NEW_LAYER_IN_PLACE", NULL },
+    { 0, NULL, NULL }
+  };
+
+  static GType type = 0;
+
+  if (G_UNLIKELY (! type))
+    {
+      type = g_enum_register_static ("GimpPasteType", values);
+      gimp_type_set_translation_context (type, "paste-type");
+      gimp_enum_set_value_descriptions (type, descs);
+    }
+
+  return type;
+}
+
+GType
+gimp_thumbnail_size_get_type (void)
+{
+  static const GEnumValue values[] =
+  {
+    { GIMP_THUMBNAIL_SIZE_NONE, "GIMP_THUMBNAIL_SIZE_NONE", "none" },
+    { GIMP_THUMBNAIL_SIZE_NORMAL, "GIMP_THUMBNAIL_SIZE_NORMAL", "normal" },
+    { GIMP_THUMBNAIL_SIZE_LARGE, "GIMP_THUMBNAIL_SIZE_LARGE", "large" },
+    { 0, NULL, NULL }
+  };
+
+  static const GimpEnumDesc descs[] =
+  {
+    { GIMP_THUMBNAIL_SIZE_NONE, NC_("thumbnail-size", "No thumbnails"), NULL },
+    { GIMP_THUMBNAIL_SIZE_NORMAL, NC_("thumbnail-size", "Normal (128x128)"), NULL },
+    { GIMP_THUMBNAIL_SIZE_LARGE, NC_("thumbnail-size", "Large (256x256)"), NULL },
+    { 0, NULL, NULL }
+  };
+
+  static GType type = 0;
+
+  if (G_UNLIKELY (! type))
+    {
+      type = g_enum_register_static ("GimpThumbnailSize", values);
+      gimp_type_set_translation_context (type, "thumbnail-size");
+      gimp_enum_set_value_descriptions (type, descs);
+    }
+
+  return type;
+}
+
+GType
+gimp_undo_event_get_type (void)
+{
+  static const GEnumValue values[] =
+  {
+    { GIMP_UNDO_EVENT_UNDO_PUSHED, "GIMP_UNDO_EVENT_UNDO_PUSHED", "undo-pushed" },
+    { GIMP_UNDO_EVENT_UNDO_EXPIRED, "GIMP_UNDO_EVENT_UNDO_EXPIRED", "undo-expired" },
+    { GIMP_UNDO_EVENT_REDO_EXPIRED, "GIMP_UNDO_EVENT_REDO_EXPIRED", "redo-expired" },
+    { GIMP_UNDO_EVENT_UNDO, "GIMP_UNDO_EVENT_UNDO", "undo" },
+    { GIMP_UNDO_EVENT_REDO, "GIMP_UNDO_EVENT_REDO", "redo" },
+    { GIMP_UNDO_EVENT_UNDO_FREE, "GIMP_UNDO_EVENT_UNDO_FREE", "undo-free" },
+    { GIMP_UNDO_EVENT_UNDO_FREEZE, "GIMP_UNDO_EVENT_UNDO_FREEZE", "undo-freeze" },
+    { GIMP_UNDO_EVENT_UNDO_THAW, "GIMP_UNDO_EVENT_UNDO_THAW", "undo-thaw" },
+    { 0, NULL, NULL }
+  };
+
+  static const GimpEnumDesc descs[] =
+  {
+    { GIMP_UNDO_EVENT_UNDO_PUSHED, "GIMP_UNDO_EVENT_UNDO_PUSHED", NULL },
+    { GIMP_UNDO_EVENT_UNDO_EXPIRED, "GIMP_UNDO_EVENT_UNDO_EXPIRED", NULL },
+    { GIMP_UNDO_EVENT_REDO_EXPIRED, "GIMP_UNDO_EVENT_REDO_EXPIRED", NULL },
+    { GIMP_UNDO_EVENT_UNDO, "GIMP_UNDO_EVENT_UNDO", NULL },
+    { GIMP_UNDO_EVENT_REDO, "GIMP_UNDO_EVENT_REDO", NULL },
+    { GIMP_UNDO_EVENT_UNDO_FREE, "GIMP_UNDO_EVENT_UNDO_FREE", NULL },
+    { GIMP_UNDO_EVENT_UNDO_FREEZE, "GIMP_UNDO_EVENT_UNDO_FREEZE", NULL },
+    { GIMP_UNDO_EVENT_UNDO_THAW, "GIMP_UNDO_EVENT_UNDO_THAW", NULL },
+    { 0, NULL, NULL }
+  };
+
+  static GType type = 0;
+
+  if (G_UNLIKELY (! type))
+    {
+      type = g_enum_register_static ("GimpUndoEvent", values);
+      gimp_type_set_translation_context (type, "undo-event");
+      gimp_enum_set_value_descriptions (type, descs);
+    }
+
+  return type;
+}
+
+GType
+gimp_undo_mode_get_type (void)
+{
+  static const GEnumValue values[] =
+  {
+    { GIMP_UNDO_MODE_UNDO, "GIMP_UNDO_MODE_UNDO", "undo" },
+    { GIMP_UNDO_MODE_REDO, "GIMP_UNDO_MODE_REDO", "redo" },
+    { 0, NULL, NULL }
+  };
+
+  static const GimpEnumDesc descs[] =
+  {
+    { GIMP_UNDO_MODE_UNDO, "GIMP_UNDO_MODE_UNDO", NULL },
+    { GIMP_UNDO_MODE_REDO, "GIMP_UNDO_MODE_REDO", NULL },
+    { 0, NULL, NULL }
+  };
+
+  static GType type = 0;
+
+  if (G_UNLIKELY (! type))
+    {
+      type = g_enum_register_static ("GimpUndoMode", values);
+      gimp_type_set_translation_context (type, "undo-mode");
+      gimp_enum_set_value_descriptions (type, descs);
+    }
+
+  return type;
+}
+
+GType
+gimp_undo_type_get_type (void)
+{
+  static const GEnumValue values[] =
+  {
+    { GIMP_UNDO_GROUP_NONE, "GIMP_UNDO_GROUP_NONE", "group-none" },
+    { GIMP_UNDO_GROUP_IMAGE_SCALE, "GIMP_UNDO_GROUP_IMAGE_SCALE", "group-image-scale" },
+    { GIMP_UNDO_GROUP_IMAGE_RESIZE, "GIMP_UNDO_GROUP_IMAGE_RESIZE", "group-image-resize" },
+    { GIMP_UNDO_GROUP_IMAGE_FLIP, "GIMP_UNDO_GROUP_IMAGE_FLIP", "group-image-flip" },
+    { GIMP_UNDO_GROUP_IMAGE_ROTATE, "GIMP_UNDO_GROUP_IMAGE_ROTATE", "group-image-rotate" },
+    { GIMP_UNDO_GROUP_IMAGE_TRANSFORM, "GIMP_UNDO_GROUP_IMAGE_TRANSFORM", "group-image-transform" },
+    { GIMP_UNDO_GROUP_IMAGE_CROP, "GIMP_UNDO_GROUP_IMAGE_CROP", "group-image-crop" },
+    { GIMP_UNDO_GROUP_IMAGE_CONVERT, "GIMP_UNDO_GROUP_IMAGE_CONVERT", "group-image-convert" },
+    { GIMP_UNDO_GROUP_IMAGE_ITEM_REMOVE, "GIMP_UNDO_GROUP_IMAGE_ITEM_REMOVE", "group-image-item-remove" },
+    { GIMP_UNDO_GROUP_IMAGE_ITEM_REORDER, "GIMP_UNDO_GROUP_IMAGE_ITEM_REORDER", "group-image-item-reorder" },
+    { GIMP_UNDO_GROUP_IMAGE_LAYERS_MERGE, "GIMP_UNDO_GROUP_IMAGE_LAYERS_MERGE", "group-image-layers-merge" },
+    { GIMP_UNDO_GROUP_IMAGE_VECTORS_MERGE, "GIMP_UNDO_GROUP_IMAGE_VECTORS_MERGE", "group-image-vectors-merge" },
+    { GIMP_UNDO_GROUP_IMAGE_QUICK_MASK, "GIMP_UNDO_GROUP_IMAGE_QUICK_MASK", "group-image-quick-mask" },
+    { GIMP_UNDO_GROUP_IMAGE_GRID, "GIMP_UNDO_GROUP_IMAGE_GRID", "group-image-grid" },
+    { GIMP_UNDO_GROUP_GUIDE, "GIMP_UNDO_GROUP_GUIDE", "group-guide" },
+    { GIMP_UNDO_GROUP_SAMPLE_POINT, "GIMP_UNDO_GROUP_SAMPLE_POINT", "group-sample-point" },
+    { GIMP_UNDO_GROUP_DRAWABLE, "GIMP_UNDO_GROUP_DRAWABLE", "group-drawable" },
+    { GIMP_UNDO_GROUP_DRAWABLE_MOD, "GIMP_UNDO_GROUP_DRAWABLE_MOD", "group-drawable-mod" },
+    { GIMP_UNDO_GROUP_MASK, "GIMP_UNDO_GROUP_MASK", "group-mask" },
+    { GIMP_UNDO_GROUP_ITEM_VISIBILITY, "GIMP_UNDO_GROUP_ITEM_VISIBILITY", "group-item-visibility" },
+    { GIMP_UNDO_GROUP_ITEM_LINKED, "GIMP_UNDO_GROUP_ITEM_LINKED", "group-item-linked" },
+    { GIMP_UNDO_GROUP_ITEM_PROPERTIES, "GIMP_UNDO_GROUP_ITEM_PROPERTIES", "group-item-properties" },
+    { GIMP_UNDO_GROUP_ITEM_DISPLACE, "GIMP_UNDO_GROUP_ITEM_DISPLACE", "group-item-displace" },
+    { GIMP_UNDO_GROUP_ITEM_SCALE, "GIMP_UNDO_GROUP_ITEM_SCALE", "group-item-scale" },
+    { GIMP_UNDO_GROUP_ITEM_RESIZE, "GIMP_UNDO_GROUP_ITEM_RESIZE", "group-item-resize" },
+    { GIMP_UNDO_GROUP_LAYER_ADD, "GIMP_UNDO_GROUP_LAYER_ADD", "group-layer-add" },
+    { GIMP_UNDO_GROUP_LAYER_ADD_MASK, "GIMP_UNDO_GROUP_LAYER_ADD_MASK", "group-layer-add-mask" },
+    { GIMP_UNDO_GROUP_LAYER_APPLY_MASK, "GIMP_UNDO_GROUP_LAYER_APPLY_MASK", "group-layer-apply-mask" },
+    { GIMP_UNDO_GROUP_FS_TO_LAYER, "GIMP_UNDO_GROUP_FS_TO_LAYER", "group-fs-to-layer" },
+    { GIMP_UNDO_GROUP_FS_FLOAT, "GIMP_UNDO_GROUP_FS_FLOAT", "group-fs-float" },
+    { GIMP_UNDO_GROUP_FS_ANCHOR, "GIMP_UNDO_GROUP_FS_ANCHOR", "group-fs-anchor" },
+    { GIMP_UNDO_GROUP_EDIT_PASTE, "GIMP_UNDO_GROUP_EDIT_PASTE", "group-edit-paste" },
+    { GIMP_UNDO_GROUP_EDIT_CUT, "GIMP_UNDO_GROUP_EDIT_CUT", "group-edit-cut" },
+    { GIMP_UNDO_GROUP_TEXT, "GIMP_UNDO_GROUP_TEXT", "group-text" },
+    { GIMP_UNDO_GROUP_TRANSFORM, "GIMP_UNDO_GROUP_TRANSFORM", "group-transform" },
+    { GIMP_UNDO_GROUP_PAINT, "GIMP_UNDO_GROUP_PAINT", "group-paint" },
+    { GIMP_UNDO_GROUP_PARASITE_ATTACH, "GIMP_UNDO_GROUP_PARASITE_ATTACH", "group-parasite-attach" },
+    { GIMP_UNDO_GROUP_PARASITE_REMOVE, "GIMP_UNDO_GROUP_PARASITE_REMOVE", "group-parasite-remove" },
+    { GIMP_UNDO_GROUP_VECTORS_IMPORT, "GIMP_UNDO_GROUP_VECTORS_IMPORT", "group-vectors-import" },
+    { GIMP_UNDO_GROUP_MISC, "GIMP_UNDO_GROUP_MISC", "group-misc" },
+    { GIMP_UNDO_IMAGE_TYPE, "GIMP_UNDO_IMAGE_TYPE", "image-type" },
+    { GIMP_UNDO_IMAGE_PRECISION, "GIMP_UNDO_IMAGE_PRECISION", "image-precision" },
+    { GIMP_UNDO_IMAGE_SIZE, "GIMP_UNDO_IMAGE_SIZE", "image-size" },
+    { GIMP_UNDO_IMAGE_RESOLUTION, "GIMP_UNDO_IMAGE_RESOLUTION", "image-resolution" },
+    { GIMP_UNDO_IMAGE_GRID, "GIMP_UNDO_IMAGE_GRID", "image-grid" },
+    { GIMP_UNDO_IMAGE_METADATA, "GIMP_UNDO_IMAGE_METADATA", "image-metadata" },
+    { GIMP_UNDO_IMAGE_COLORMAP, "GIMP_UNDO_IMAGE_COLORMAP", "image-colormap" },
+    { GIMP_UNDO_IMAGE_COLOR_MANAGED, "GIMP_UNDO_IMAGE_COLOR_MANAGED", "image-color-managed" },
+    { GIMP_UNDO_GUIDE, "GIMP_UNDO_GUIDE", "guide" },
+    { GIMP_UNDO_SAMPLE_POINT, "GIMP_UNDO_SAMPLE_POINT", "sample-point" },
+    { GIMP_UNDO_DRAWABLE, "GIMP_UNDO_DRAWABLE", "drawable" },
+    { GIMP_UNDO_DRAWABLE_MOD, "GIMP_UNDO_DRAWABLE_MOD", "drawable-mod" },
+    { GIMP_UNDO_MASK, "GIMP_UNDO_MASK", "mask" },
+    { GIMP_UNDO_ITEM_REORDER, "GIMP_UNDO_ITEM_REORDER", "item-reorder" },
+    { GIMP_UNDO_ITEM_RENAME, "GIMP_UNDO_ITEM_RENAME", "item-rename" },
+    { GIMP_UNDO_ITEM_DISPLACE, "GIMP_UNDO_ITEM_DISPLACE", "item-displace" },
+    { GIMP_UNDO_ITEM_VISIBILITY, "GIMP_UNDO_ITEM_VISIBILITY", "item-visibility" },
+    { GIMP_UNDO_ITEM_LINKED, "GIMP_UNDO_ITEM_LINKED", "item-linked" },
+    { GIMP_UNDO_ITEM_COLOR_TAG, "GIMP_UNDO_ITEM_COLOR_TAG", "item-color-tag" },
+    { GIMP_UNDO_ITEM_LOCK_CONTENT, "GIMP_UNDO_ITEM_LOCK_CONTENT", "item-lock-content" },
+    { GIMP_UNDO_ITEM_LOCK_POSITION, "GIMP_UNDO_ITEM_LOCK_POSITION", "item-lock-position" },
+    { GIMP_UNDO_LAYER_ADD, "GIMP_UNDO_LAYER_ADD", "layer-add" },
+    { GIMP_UNDO_LAYER_REMOVE, "GIMP_UNDO_LAYER_REMOVE", "layer-remove" },
+    { GIMP_UNDO_LAYER_MODE, "GIMP_UNDO_LAYER_MODE", "layer-mode" },
+    { GIMP_UNDO_LAYER_OPACITY, "GIMP_UNDO_LAYER_OPACITY", "layer-opacity" },
+    { GIMP_UNDO_LAYER_LOCK_ALPHA, "GIMP_UNDO_LAYER_LOCK_ALPHA", "layer-lock-alpha" },
+    { GIMP_UNDO_GROUP_LAYER_SUSPEND_RESIZE, "GIMP_UNDO_GROUP_LAYER_SUSPEND_RESIZE", "group-layer-suspend-resize" },
+    { GIMP_UNDO_GROUP_LAYER_RESUME_RESIZE, "GIMP_UNDO_GROUP_LAYER_RESUME_RESIZE", "group-layer-resume-resize" },
+    { GIMP_UNDO_GROUP_LAYER_SUSPEND_MASK, "GIMP_UNDO_GROUP_LAYER_SUSPEND_MASK", "group-layer-suspend-mask" },
+    { GIMP_UNDO_GROUP_LAYER_RESUME_MASK, "GIMP_UNDO_GROUP_LAYER_RESUME_MASK", "group-layer-resume-mask" },
+    { GIMP_UNDO_GROUP_LAYER_START_TRANSFORM, "GIMP_UNDO_GROUP_LAYER_START_TRANSFORM", "group-layer-start-transform" },
+    { GIMP_UNDO_GROUP_LAYER_END_TRANSFORM, "GIMP_UNDO_GROUP_LAYER_END_TRANSFORM", "group-layer-end-transform" },
+    { GIMP_UNDO_GROUP_LAYER_CONVERT, "GIMP_UNDO_GROUP_LAYER_CONVERT", "group-layer-convert" },
+    { GIMP_UNDO_TEXT_LAYER, "GIMP_UNDO_TEXT_LAYER", "text-layer" },
+    { GIMP_UNDO_TEXT_LAYER_MODIFIED, "GIMP_UNDO_TEXT_LAYER_MODIFIED", "text-layer-modified" },
+    { GIMP_UNDO_TEXT_LAYER_CONVERT, "GIMP_UNDO_TEXT_LAYER_CONVERT", "text-layer-convert" },
+    { GIMP_UNDO_LAYER_MASK_ADD, "GIMP_UNDO_LAYER_MASK_ADD", "layer-mask-add" },
+    { GIMP_UNDO_LAYER_MASK_REMOVE, "GIMP_UNDO_LAYER_MASK_REMOVE", "layer-mask-remove" },
+    { GIMP_UNDO_LAYER_MASK_APPLY, "GIMP_UNDO_LAYER_MASK_APPLY", "layer-mask-apply" },
+    { GIMP_UNDO_LAYER_MASK_SHOW, "GIMP_UNDO_LAYER_MASK_SHOW", "layer-mask-show" },
+    { GIMP_UNDO_CHANNEL_ADD, "GIMP_UNDO_CHANNEL_ADD", "channel-add" },
+    { GIMP_UNDO_CHANNEL_REMOVE, "GIMP_UNDO_CHANNEL_REMOVE", "channel-remove" },
+    { GIMP_UNDO_CHANNEL_COLOR, "GIMP_UNDO_CHANNEL_COLOR", "channel-color" },
+    { GIMP_UNDO_VECTORS_ADD, "GIMP_UNDO_VECTORS_ADD", "vectors-add" },
+    { GIMP_UNDO_VECTORS_REMOVE, "GIMP_UNDO_VECTORS_REMOVE", "vectors-remove" },
+    { GIMP_UNDO_VECTORS_MOD, "GIMP_UNDO_VECTORS_MOD", "vectors-mod" },
+    { GIMP_UNDO_FS_TO_LAYER, "GIMP_UNDO_FS_TO_LAYER", "fs-to-layer" },
+    { GIMP_UNDO_TRANSFORM_GRID, "GIMP_UNDO_TRANSFORM_GRID", "transform-grid" },
+    { GIMP_UNDO_PAINT, "GIMP_UNDO_PAINT", "paint" },
+    { GIMP_UNDO_INK, "GIMP_UNDO_INK", "ink" },
+    { GIMP_UNDO_FOREGROUND_SELECT, "GIMP_UNDO_FOREGROUND_SELECT", "foreground-select" },
+    { GIMP_UNDO_PARASITE_ATTACH, "GIMP_UNDO_PARASITE_ATTACH", "parasite-attach" },
+    { GIMP_UNDO_PARASITE_REMOVE, "GIMP_UNDO_PARASITE_REMOVE", "parasite-remove" },
+    { GIMP_UNDO_CANT, "GIMP_UNDO_CANT", "cant" },
+    { 0, NULL, NULL }
+  };
+
+  static const GimpEnumDesc descs[] =
+  {
+    { GIMP_UNDO_GROUP_NONE, NC_("undo-type", "<<invalid>>"), NULL },
+    { GIMP_UNDO_GROUP_IMAGE_SCALE, NC_("undo-type", "Scale image"), NULL },
+    { GIMP_UNDO_GROUP_IMAGE_RESIZE, NC_("undo-type", "Resize image"), NULL },
+    { GIMP_UNDO_GROUP_IMAGE_FLIP, NC_("undo-type", "Flip image"), NULL },
+    { GIMP_UNDO_GROUP_IMAGE_ROTATE, NC_("undo-type", "Rotate image"), NULL },
+    { GIMP_UNDO_GROUP_IMAGE_TRANSFORM, NC_("undo-type", "Transform image"), NULL },
+    { GIMP_UNDO_GROUP_IMAGE_CROP, NC_("undo-type", "Crop image"), NULL },
+    { GIMP_UNDO_GROUP_IMAGE_CONVERT, NC_("undo-type", "Convert image"), NULL },
+    { GIMP_UNDO_GROUP_IMAGE_ITEM_REMOVE, NC_("undo-type", "Remove item"), NULL },
+    { GIMP_UNDO_GROUP_IMAGE_ITEM_REORDER, NC_("undo-type", "Reorder item"), NULL },
+    { GIMP_UNDO_GROUP_IMAGE_LAYERS_MERGE, NC_("undo-type", "Merge layers"), NULL },
+    { GIMP_UNDO_GROUP_IMAGE_VECTORS_MERGE, NC_("undo-type", "Merge paths"), NULL },
+    { GIMP_UNDO_GROUP_IMAGE_QUICK_MASK, NC_("undo-type", "Quick Mask"), NULL },
+    { GIMP_UNDO_GROUP_IMAGE_GRID, NC_("undo-type", "Grid"), NULL },
+    { GIMP_UNDO_GROUP_GUIDE, NC_("undo-type", "Guide"), NULL },
+    { GIMP_UNDO_GROUP_SAMPLE_POINT, NC_("undo-type", "Sample Point"), NULL },
+    { GIMP_UNDO_GROUP_DRAWABLE, NC_("undo-type", "Layer/Channel"), NULL },
+    { GIMP_UNDO_GROUP_DRAWABLE_MOD, NC_("undo-type", "Layer/Channel modification"), NULL },
+    { GIMP_UNDO_GROUP_MASK, NC_("undo-type", "Selection mask"), NULL },
+    { GIMP_UNDO_GROUP_ITEM_VISIBILITY, NC_("undo-type", "Item visibility"), NULL },
+    { GIMP_UNDO_GROUP_ITEM_LINKED, NC_("undo-type", "Link/Unlink item"), NULL },
+    { GIMP_UNDO_GROUP_ITEM_PROPERTIES, NC_("undo-type", "Item properties"), NULL },
+    { GIMP_UNDO_GROUP_ITEM_DISPLACE, NC_("undo-type", "Move item"), NULL },
+    { GIMP_UNDO_GROUP_ITEM_SCALE, NC_("undo-type", "Scale item"), NULL },
+    { GIMP_UNDO_GROUP_ITEM_RESIZE, NC_("undo-type", "Resize item"), NULL },
+    { GIMP_UNDO_GROUP_LAYER_ADD, NC_("undo-type", "Add layer"), NULL },
+    { GIMP_UNDO_GROUP_LAYER_ADD_MASK, NC_("undo-type", "Add layer mask"), NULL },
+    { GIMP_UNDO_GROUP_LAYER_APPLY_MASK, NC_("undo-type", "Apply layer mask"), NULL },
+    { GIMP_UNDO_GROUP_FS_TO_LAYER, NC_("undo-type", "Floating selection to layer"), NULL },
+    { GIMP_UNDO_GROUP_FS_FLOAT, NC_("undo-type", "Float selection"), NULL },
+    { GIMP_UNDO_GROUP_FS_ANCHOR, NC_("undo-type", "Anchor floating selection"), NULL },
+    { GIMP_UNDO_GROUP_EDIT_PASTE, NC_("undo-type", "Paste"), NULL },
+    { GIMP_UNDO_GROUP_EDIT_CUT, NC_("undo-type", "Cut"), NULL },
+    { GIMP_UNDO_GROUP_TEXT, NC_("undo-type", "Text"), NULL },
+    { GIMP_UNDO_GROUP_TRANSFORM, NC_("undo-type", "Transform"), NULL },
+    { GIMP_UNDO_GROUP_PAINT, NC_("undo-type", "Paint"), NULL },
+    { GIMP_UNDO_GROUP_PARASITE_ATTACH, NC_("undo-type", "Attach parasite"), NULL },
+    { GIMP_UNDO_GROUP_PARASITE_REMOVE, NC_("undo-type", "Remove parasite"), NULL },
+    { GIMP_UNDO_GROUP_VECTORS_IMPORT, NC_("undo-type", "Import paths"), NULL },
+    { GIMP_UNDO_GROUP_MISC, NC_("undo-type", "Plug-In"), NULL },
+    { GIMP_UNDO_IMAGE_TYPE, NC_("undo-type", "Image type"), NULL },
+    { GIMP_UNDO_IMAGE_PRECISION, NC_("undo-type", "Image precision"), NULL },
+    { GIMP_UNDO_IMAGE_SIZE, NC_("undo-type", "Image size"), NULL },
+    { GIMP_UNDO_IMAGE_RESOLUTION, NC_("undo-type", "Image resolution change"), NULL },
+    { GIMP_UNDO_IMAGE_GRID, NC_("undo-type", "Grid"), NULL },
+    { GIMP_UNDO_IMAGE_METADATA, NC_("undo-type", "Change metadata"), NULL },
+    { GIMP_UNDO_IMAGE_COLORMAP, NC_("undo-type", "Change indexed palette"), NULL },
+    { GIMP_UNDO_IMAGE_COLOR_MANAGED, NC_("undo-type", "Change color managed state"), NULL },
+    { GIMP_UNDO_GUIDE, NC_("undo-type", "Guide"), NULL },
+    { GIMP_UNDO_SAMPLE_POINT, NC_("undo-type", "Sample Point"), NULL },
+    { GIMP_UNDO_DRAWABLE, NC_("undo-type", "Layer/Channel"), NULL },
+    { GIMP_UNDO_DRAWABLE_MOD, NC_("undo-type", "Layer/Channel modification"), NULL },
+    { GIMP_UNDO_MASK, NC_("undo-type", "Selection mask"), NULL },
+    { GIMP_UNDO_ITEM_REORDER, NC_("undo-type", "Reorder item"), NULL },
+    { GIMP_UNDO_ITEM_RENAME, NC_("undo-type", "Rename item"), NULL },
+    { GIMP_UNDO_ITEM_DISPLACE, NC_("undo-type", "Move item"), NULL },
+    { GIMP_UNDO_ITEM_VISIBILITY, NC_("undo-type", "Item visibility"), NULL },
+    { GIMP_UNDO_ITEM_LINKED, NC_("undo-type", "Link/Unlink item"), NULL },
+    { GIMP_UNDO_ITEM_COLOR_TAG, NC_("undo-type", "Item color tag"), NULL },
+    { GIMP_UNDO_ITEM_LOCK_CONTENT, NC_("undo-type", "Lock/Unlock content"), NULL },
+    { GIMP_UNDO_ITEM_LOCK_POSITION, NC_("undo-type", "Lock/Unlock position"), NULL },
+    { GIMP_UNDO_LAYER_ADD, NC_("undo-type", "New layer"), NULL },
+    { GIMP_UNDO_LAYER_REMOVE, NC_("undo-type", "Delete layer"), NULL },
+    { GIMP_UNDO_LAYER_MODE, NC_("undo-type", "Set layer mode"), NULL },
+    { GIMP_UNDO_LAYER_OPACITY, NC_("undo-type", "Set layer opacity"), NULL },
+    { GIMP_UNDO_LAYER_LOCK_ALPHA, NC_("undo-type", "Lock/Unlock alpha channel"), NULL },
+    { GIMP_UNDO_GROUP_LAYER_SUSPEND_RESIZE, NC_("undo-type", "Suspend group layer resize"), NULL },
+    { GIMP_UNDO_GROUP_LAYER_RESUME_RESIZE, NC_("undo-type", "Resume group layer resize"), NULL },
+    { GIMP_UNDO_GROUP_LAYER_SUSPEND_MASK, NC_("undo-type", "Suspend group layer mask"), NULL },
+    { GIMP_UNDO_GROUP_LAYER_RESUME_MASK, NC_("undo-type", "Resume group layer mask"), NULL },
+    { GIMP_UNDO_GROUP_LAYER_START_TRANSFORM, NC_("undo-type", "Start transforming group layer"), NULL },
+    { GIMP_UNDO_GROUP_LAYER_END_TRANSFORM, NC_("undo-type", "End transforming group layer"), NULL },
+    { GIMP_UNDO_GROUP_LAYER_CONVERT, NC_("undo-type", "Convert group layer"), NULL },
+    { GIMP_UNDO_TEXT_LAYER, NC_("undo-type", "Text layer"), NULL },
+    { GIMP_UNDO_TEXT_LAYER_MODIFIED, NC_("undo-type", "Text layer modification"), NULL },
+    { GIMP_UNDO_TEXT_LAYER_CONVERT, NC_("undo-type", "Convert text layer"), NULL },
+    { GIMP_UNDO_LAYER_MASK_ADD, NC_("undo-type", "Add layer mask"), NULL },
+    { GIMP_UNDO_LAYER_MASK_REMOVE, NC_("undo-type", "Delete layer mask"), NULL },
+    { GIMP_UNDO_LAYER_MASK_APPLY, NC_("undo-type", "Apply layer mask"), NULL },
+    { GIMP_UNDO_LAYER_MASK_SHOW, NC_("undo-type", "Show layer mask"), NULL },
+    { GIMP_UNDO_CHANNEL_ADD, NC_("undo-type", "New channel"), NULL },
+    { GIMP_UNDO_CHANNEL_REMOVE, NC_("undo-type", "Delete channel"), NULL },
+    { GIMP_UNDO_CHANNEL_COLOR, NC_("undo-type", "Channel color"), NULL },
+    { GIMP_UNDO_VECTORS_ADD, NC_("undo-type", "New path"), NULL },
+    { GIMP_UNDO_VECTORS_REMOVE, NC_("undo-type", "Delete path"), NULL },
+    { GIMP_UNDO_VECTORS_MOD, NC_("undo-type", "Path modification"), NULL },
+    { GIMP_UNDO_FS_TO_LAYER, NC_("undo-type", "Floating selection to layer"), NULL },
+    { GIMP_UNDO_TRANSFORM_GRID, NC_("undo-type", "Transform grid"), NULL },
+    { GIMP_UNDO_PAINT, NC_("undo-type", "Paint"), NULL },
+    { GIMP_UNDO_INK, NC_("undo-type", "Ink"), NULL },
+    { GIMP_UNDO_FOREGROUND_SELECT, NC_("undo-type", "Select foreground"), NULL },
+    { GIMP_UNDO_PARASITE_ATTACH, NC_("undo-type", "Attach parasite"), NULL },
+    { GIMP_UNDO_PARASITE_REMOVE, NC_("undo-type", "Remove parasite"), NULL },
+    { GIMP_UNDO_CANT, NC_("undo-type", "Not undoable"), NULL },
+    { 0, NULL, NULL }
+  };
+
+  static GType type = 0;
+
+  if (G_UNLIKELY (! type))
+    {
+      type = g_enum_register_static ("GimpUndoType", values);
+      gimp_type_set_translation_context (type, "undo-type");
+      gimp_enum_set_value_descriptions (type, descs);
+    }
+
+  return type;
+}
+
+GType
+gimp_view_size_get_type (void)
+{
+  static const GEnumValue values[] =
+  {
+    { GIMP_VIEW_SIZE_TINY, "GIMP_VIEW_SIZE_TINY", "tiny" },
+    { GIMP_VIEW_SIZE_EXTRA_SMALL, "GIMP_VIEW_SIZE_EXTRA_SMALL", "extra-small" },
+    { GIMP_VIEW_SIZE_SMALL, "GIMP_VIEW_SIZE_SMALL", "small" },
+    { GIMP_VIEW_SIZE_MEDIUM, "GIMP_VIEW_SIZE_MEDIUM", "medium" },
+    { GIMP_VIEW_SIZE_LARGE, "GIMP_VIEW_SIZE_LARGE", "large" },
+    { GIMP_VIEW_SIZE_EXTRA_LARGE, "GIMP_VIEW_SIZE_EXTRA_LARGE", "extra-large" },
+    { GIMP_VIEW_SIZE_HUGE, "GIMP_VIEW_SIZE_HUGE", "huge" },
+    { GIMP_VIEW_SIZE_ENORMOUS, "GIMP_VIEW_SIZE_ENORMOUS", "enormous" },
+    { GIMP_VIEW_SIZE_GIGANTIC, "GIMP_VIEW_SIZE_GIGANTIC", "gigantic" },
+    { 0, NULL, NULL }
+  };
+
+  static const GimpEnumDesc descs[] =
+  {
+    { GIMP_VIEW_SIZE_TINY, NC_("view-size", "Tiny"), NULL },
+    { GIMP_VIEW_SIZE_EXTRA_SMALL, NC_("view-size", "Very small"), NULL },
+    { GIMP_VIEW_SIZE_SMALL, NC_("view-size", "Small"), NULL },
+    { GIMP_VIEW_SIZE_MEDIUM, NC_("view-size", "Medium"), NULL },
+    { GIMP_VIEW_SIZE_LARGE, NC_("view-size", "Large"), NULL },
+    { GIMP_VIEW_SIZE_EXTRA_LARGE, NC_("view-size", "Very large"), NULL },
+    { GIMP_VIEW_SIZE_HUGE, NC_("view-size", "Huge"), NULL },
+    { GIMP_VIEW_SIZE_ENORMOUS, NC_("view-size", "Enormous"), NULL },
+    { GIMP_VIEW_SIZE_GIGANTIC, NC_("view-size", "Gigantic"), NULL },
+    { 0, NULL, NULL }
+  };
+
+  static GType type = 0;
+
+  if (G_UNLIKELY (! type))
+    {
+      type = g_enum_register_static ("GimpViewSize", values);
+      gimp_type_set_translation_context (type, "view-size");
+      gimp_enum_set_value_descriptions (type, descs);
+    }
+
+  return type;
+}
+
+GType
+gimp_view_type_get_type (void)
+{
+  static const GEnumValue values[] =
+  {
+    { GIMP_VIEW_TYPE_LIST, "GIMP_VIEW_TYPE_LIST", "list" },
+    { GIMP_VIEW_TYPE_GRID, "GIMP_VIEW_TYPE_GRID", "grid" },
+    { 0, NULL, NULL }
+  };
+
+  static const GimpEnumDesc descs[] =
+  {
+    { GIMP_VIEW_TYPE_LIST, NC_("view-type", "View as list"), NULL },
+    { GIMP_VIEW_TYPE_GRID, NC_("view-type", "View as grid"), NULL },
+    { 0, NULL, NULL }
+  };
+
+  static GType type = 0;
+
+  if (G_UNLIKELY (! type))
+    {
+      type = g_enum_register_static ("GimpViewType", values);
+      gimp_type_set_translation_context (type, "view-type");
+      gimp_enum_set_value_descriptions (type, descs);
+    }
+
+  return type;
+}
+
+
+/* Generated data ends here */
+
diff --git a/app/core/core-enums.h b/app/core/core-enums.h
new file mode 100644
index 0000000..8826145
--- /dev/null
+++ b/app/core/core-enums.h
@@ -0,0 +1,701 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __CORE_ENUMS_H__
+#define __CORE_ENUMS_H__
+
+
+#if 0
+   This file is parsed by two scripts, enumgen.pl in pdb,
+   and gimp-mkenums. All enums that are not marked with
+   /*< pdb-skip >*/ are exported to libgimp and the PDB. Enums that are
+   not marked with /*< skip >*/ are registered with the GType system.
+   If you want the enum to be skipped by both scripts, you have to use
+   /*< pdb-skip, skip >*/.
+
+   The same syntax applies to enum values.
+#endif
+
+
+/*
+ * these enums are registered with the type system
+ */
+
+
+#define GIMP_TYPE_ALIGN_REFERENCE_TYPE (gimp_align_reference_type_get_type ())
+
+GType gimp_align_reference_type_get_type (void) G_GNUC_CONST;
+
+typedef enum  /*< pdb-skip >*/
+{
+  GIMP_ALIGN_REFERENCE_FIRST,          /*< desc="First item"     >*/
+  GIMP_ALIGN_REFERENCE_IMAGE,          /*< desc="Image"          >*/
+  GIMP_ALIGN_REFERENCE_SELECTION,      /*< desc="Selection"      >*/
+  GIMP_ALIGN_REFERENCE_ACTIVE_LAYER,   /*< desc="Active layer"   >*/
+  GIMP_ALIGN_REFERENCE_ACTIVE_CHANNEL, /*< desc="Active channel" >*/
+  GIMP_ALIGN_REFERENCE_ACTIVE_PATH     /*< desc="Active path"    >*/
+} GimpAlignReferenceType;
+
+
+#define GIMP_TYPE_ALIGNMENT_TYPE (gimp_alignment_type_get_type ())
+
+GType gimp_alignment_type_get_type (void) G_GNUC_CONST;
+
+typedef enum  /*< pdb-skip >*/
+{
+  GIMP_ALIGN_LEFT,
+  GIMP_ALIGN_HCENTER,
+  GIMP_ALIGN_RIGHT,
+  GIMP_ALIGN_TOP,
+  GIMP_ALIGN_VCENTER,
+  GIMP_ALIGN_BOTTOM,
+  GIMP_ARRANGE_LEFT,
+  GIMP_ARRANGE_HCENTER,
+  GIMP_ARRANGE_RIGHT,
+  GIMP_ARRANGE_TOP,
+  GIMP_ARRANGE_VCENTER,
+  GIMP_ARRANGE_BOTTOM,
+  GIMP_ARRANGE_HFILL,
+  GIMP_ARRANGE_VFILL
+} GimpAlignmentType;
+
+
+#define GIMP_TYPE_CHANNEL_BORDER_STYLE (gimp_channel_border_style_get_type ())
+
+GType gimp_channel_border_style_get_type (void) G_GNUC_CONST;
+
+typedef enum  /*< pdb-skip >*/
+{
+  GIMP_CHANNEL_BORDER_STYLE_HARD,     /*< desc="Hard"      >*/
+  GIMP_CHANNEL_BORDER_STYLE_SMOOTH,   /*< desc="Smooth"    >*/
+  GIMP_CHANNEL_BORDER_STYLE_FEATHERED /*< desc="Feathered" >*/
+} GimpChannelBorderStyle;
+
+
+/*  Note: when appending values here, don't forget to update
+ *  GimpColorFrame and other places use this enum to create combo
+ *  boxes.
+ */
+#define GIMP_TYPE_COLOR_PICK_MODE (gimp_color_pick_mode_get_type ())
+
+GType gimp_color_pick_mode_get_type (void) G_GNUC_CONST;
+
+typedef enum  /*< pdb-skip >*/
+{
+  GIMP_COLOR_PICK_MODE_PIXEL,       /*< desc="Pixel"        >*/
+  GIMP_COLOR_PICK_MODE_RGB_PERCENT, /*< desc="RGB (%)"      >*/
+  GIMP_COLOR_PICK_MODE_RGB_U8,      /*< desc="RGB (0..255)" >*/
+  GIMP_COLOR_PICK_MODE_HSV,         /*< desc="HSV"          >*/
+  GIMP_COLOR_PICK_MODE_LCH,         /*< desc="CIE LCh"      >*/
+  GIMP_COLOR_PICK_MODE_LAB,         /*< desc="CIE LAB"      >*/
+  GIMP_COLOR_PICK_MODE_CMYK,        /*< desc="CMYK"         >*/
+  GIMP_COLOR_PICK_MODE_XYY,         /*< desc="CIE xyY"      >*/
+  GIMP_COLOR_PICK_MODE_YUV,         /*< desc="CIE Yu'v'"      >*/
+
+  GIMP_COLOR_PICK_MODE_LAST = GIMP_COLOR_PICK_MODE_YUV /*< skip >*/
+} GimpColorPickMode;
+
+
+#define GIMP_TYPE_COLOR_PROFILE_POLICY (gimp_color_profile_policy_get_type ())
+
+GType gimp_color_profile_policy_get_type (void) G_GNUC_CONST;
+
+typedef enum  /*< pdb-skip >*/
+{
+  GIMP_COLOR_PROFILE_POLICY_ASK,    /*< desc="Ask what to do"           >*/
+  GIMP_COLOR_PROFILE_POLICY_KEEP,   /*< desc="Keep embedded profile"    >*/
+  GIMP_COLOR_PROFILE_POLICY_CONVERT /*< desc="Convert to built-in sRGB or grayscale profile" >*/
+} GimpColorProfilePolicy;
+
+
+#define GIMP_TYPE_COMPONENT_MASK (gimp_component_mask_get_type ())
+
+GType gimp_component_mask_get_type (void) G_GNUC_CONST;
+
+typedef enum /*< pdb-skip >*/
+{
+  GIMP_COMPONENT_MASK_RED   = 1 << 0,
+  GIMP_COMPONENT_MASK_GREEN = 1 << 1,
+  GIMP_COMPONENT_MASK_BLUE  = 1 << 2,
+  GIMP_COMPONENT_MASK_ALPHA = 1 << 3,
+
+  GIMP_COMPONENT_MASK_ALL = (GIMP_COMPONENT_MASK_RED   |
+                             GIMP_COMPONENT_MASK_GREEN |
+                             GIMP_COMPONENT_MASK_BLUE  |
+                             GIMP_COMPONENT_MASK_ALPHA)
+} GimpComponentMask;
+
+
+#define GIMP_TYPE_CONTAINER_POLICY (gimp_container_policy_get_type ())
+
+GType gimp_container_policy_get_type (void) G_GNUC_CONST;
+
+typedef enum  /*< pdb-skip >*/
+{
+  GIMP_CONTAINER_POLICY_STRONG,
+  GIMP_CONTAINER_POLICY_WEAK
+} GimpContainerPolicy;
+
+
+#define GIMP_TYPE_CONVERT_DITHER_TYPE (gimp_convert_dither_type_get_type ())
+
+GType gimp_convert_dither_type_get_type (void) G_GNUC_CONST;
+
+typedef enum
+{
+  GIMP_CONVERT_DITHER_NONE,        /*< desc="None"                                     >*/
+  GIMP_CONVERT_DITHER_FS,          /*< desc="Floyd-Steinberg (normal)"                 >*/
+  GIMP_CONVERT_DITHER_FS_LOWBLEED, /*< desc="Floyd-Steinberg (reduced color bleeding)" >*/
+  GIMP_CONVERT_DITHER_FIXED,       /*< desc="Positioned"                               >*/
+  GIMP_CONVERT_DITHER_NODESTRUCT   /*< pdb-skip, skip >*/
+} GimpConvertDitherType;
+
+
+#define GIMP_TYPE_CONVOLUTION_TYPE (gimp_convolution_type_get_type ())
+
+GType gimp_convolution_type_get_type (void) G_GNUC_CONST;
+
+typedef enum  /*< pdb-skip >*/
+{
+  GIMP_NORMAL_CONVOL,      /*  Negative numbers truncated  */
+  GIMP_ABSOLUTE_CONVOL,    /*  Absolute value              */
+  GIMP_NEGATIVE_CONVOL     /*  add 127 to values           */
+} GimpConvolutionType;
+
+
+#define GIMP_TYPE_CURVE_POINT_TYPE (gimp_curve_point_type_get_type ())
+
+GType gimp_curve_point_type_get_type (void) G_GNUC_CONST;
+
+typedef enum  /*< pdb-skip >*/
+{
+  GIMP_CURVE_POINT_SMOOTH,   /*< desc="Smooth" >*/
+  GIMP_CURVE_POINT_CORNER    /*< desc="Corner" >*/
+} GimpCurvePointType;
+
+
+#define GIMP_TYPE_CURVE_TYPE (gimp_curve_type_get_type ())
+
+GType gimp_curve_type_get_type (void) G_GNUC_CONST;
+
+typedef enum  /*< pdb-skip >*/
+{
+  GIMP_CURVE_SMOOTH,   /*< desc="Smooth"   >*/
+  GIMP_CURVE_FREE      /*< desc="Freehand" >*/
+} GimpCurveType;
+
+
+#define GIMP_TYPE_DASH_PRESET (gimp_dash_preset_get_type ())
+
+GType gimp_dash_preset_get_type (void) G_GNUC_CONST;
+
+typedef enum  /*< pdb-skip >*/
+{
+  GIMP_DASH_CUSTOM,       /*< desc="Custom"         >*/
+  GIMP_DASH_LINE,         /*< desc="Line"           >*/
+  GIMP_DASH_LONG_DASH,    /*< desc="Long dashes"    >*/
+  GIMP_DASH_MEDIUM_DASH,  /*< desc="Medium dashes"  >*/
+  GIMP_DASH_SHORT_DASH,   /*< desc="Short dashes"   >*/
+  GIMP_DASH_SPARSE_DOTS,  /*< desc="Sparse dots"    >*/
+  GIMP_DASH_NORMAL_DOTS,  /*< desc="Normal dots"    >*/
+  GIMP_DASH_DENSE_DOTS,   /*< desc="Dense dots"     >*/
+  GIMP_DASH_STIPPLES,     /*< desc="Stipples"       >*/
+  GIMP_DASH_DASH_DOT,     /*< desc="Dash, dot"      >*/
+  GIMP_DASH_DASH_DOT_DOT  /*< desc="Dash, dot, dot" >*/
+} GimpDashPreset;
+
+
+#define GIMP_TYPE_DEBUG_POLICY (gimp_debug_policy_get_type ())
+
+GType gimp_debug_policy_get_type (void) G_GNUC_CONST;
+
+typedef enum  /*< pdb-skip >*/
+{
+  GIMP_DEBUG_POLICY_WARNING,    /*< desc="Debug warnings, critical errors and crashes" >*/
+  GIMP_DEBUG_POLICY_CRITICAL,   /*< desc="Debug critical errors and crashes"           >*/
+  GIMP_DEBUG_POLICY_FATAL,      /*< desc="Debug crashes only"                          >*/
+  GIMP_DEBUG_POLICY_NEVER       /*< desc="Never debug GIMP"                            >*/
+} GimpDebugPolicy;
+
+
+#define GIMP_TYPE_DIRTY_MASK (gimp_dirty_mask_get_type ())
+
+GType gimp_dirty_mask_get_type (void) G_GNUC_CONST;
+
+typedef enum  /*< pdb-skip >*/
+{
+  GIMP_DIRTY_NONE            = 0,
+
+  GIMP_DIRTY_IMAGE           = 1 << 0,
+  GIMP_DIRTY_IMAGE_SIZE      = 1 << 1,
+  GIMP_DIRTY_IMAGE_META      = 1 << 2,
+  GIMP_DIRTY_IMAGE_STRUCTURE = 1 << 3,
+  GIMP_DIRTY_ITEM            = 1 << 4,
+  GIMP_DIRTY_ITEM_META       = 1 << 5,
+  GIMP_DIRTY_DRAWABLE        = 1 << 6,
+  GIMP_DIRTY_VECTORS         = 1 << 7,
+  GIMP_DIRTY_SELECTION       = 1 << 8,
+  GIMP_DIRTY_ACTIVE_DRAWABLE = 1 << 9,
+
+  GIMP_DIRTY_ALL             = 0xffff
+} GimpDirtyMask;
+
+
+#define GIMP_TYPE_DYNAMICS_OUTPUT_TYPE (gimp_dynamics_output_type_get_type ())
+
+GType gimp_dynamics_output_type_get_type (void) G_GNUC_CONST;
+
+typedef enum  /*< pdb-skip >*/
+{
+  GIMP_DYNAMICS_OUTPUT_OPACITY,      /*< desc="Opacity"      >*/
+  GIMP_DYNAMICS_OUTPUT_SIZE,         /*< desc="Size"         >*/
+  GIMP_DYNAMICS_OUTPUT_ANGLE,        /*< desc="Angle"        >*/
+  GIMP_DYNAMICS_OUTPUT_COLOR,        /*< desc="Color"        >*/
+  GIMP_DYNAMICS_OUTPUT_HARDNESS,     /*< desc="Hardness"     >*/
+  GIMP_DYNAMICS_OUTPUT_FORCE,        /*< desc="Force"        >*/
+  GIMP_DYNAMICS_OUTPUT_ASPECT_RATIO, /*< desc="Aspect ratio" >*/
+  GIMP_DYNAMICS_OUTPUT_SPACING,      /*< desc="Spacing"      >*/
+  GIMP_DYNAMICS_OUTPUT_RATE,         /*< desc="Rate"         >*/
+  GIMP_DYNAMICS_OUTPUT_FLOW,         /*< desc="Flow"         >*/
+  GIMP_DYNAMICS_OUTPUT_JITTER,       /*< desc="Jitter"       >*/
+} GimpDynamicsOutputType;
+
+
+#define GIMP_TYPE_FILL_STYLE (gimp_fill_style_get_type ())
+
+GType gimp_fill_style_get_type (void) G_GNUC_CONST;
+
+typedef enum  /*< pdb-skip >*/
+{
+  GIMP_FILL_STYLE_SOLID,  /*< desc="Solid color" >*/
+  GIMP_FILL_STYLE_PATTERN /*< desc="Pattern"     >*/
+} GimpFillStyle;
+
+
+#define GIMP_TYPE_FILTER_REGION (gimp_filter_region_get_type ())
+
+GType gimp_filter_region_get_type (void) G_GNUC_CONST;
+
+typedef enum  /*< pdb-skip >*/
+{
+  GIMP_FILTER_REGION_SELECTION, /*< desc="Use the selection as input"    >*/
+  GIMP_FILTER_REGION_DRAWABLE   /*< desc="Use the entire layer as input" >*/
+} GimpFilterRegion;
+
+
+#define GIMP_TYPE_GRADIENT_COLOR (gimp_gradient_color_get_type ())
+
+GType gimp_gradient_color_get_type (void) G_GNUC_CONST;
+
+typedef enum  /*< pdb-skip >*/
+{
+  GIMP_GRADIENT_COLOR_FIXED,                  /*< desc="Fixed"                                           >*/
+  GIMP_GRADIENT_COLOR_FOREGROUND,             /*< desc="Foreground color",               abbrev="FG"     >*/
+  GIMP_GRADIENT_COLOR_FOREGROUND_TRANSPARENT, /*< desc="Foreground color (transparent)",  abbrev="FG (t)" >*/
+  GIMP_GRADIENT_COLOR_BACKGROUND,             /*< desc="Background color",               abbrev="BG"     >*/
+  GIMP_GRADIENT_COLOR_BACKGROUND_TRANSPARENT  /*< desc="Background color (transparent)", abbrev="BG (t)" >*/
+} GimpGradientColor;
+
+
+#define GIMP_TYPE_GRAVITY_TYPE (gimp_gravity_type_get_type ())
+
+GType gimp_gravity_type_get_type (void) G_GNUC_CONST;
+
+typedef enum  /*< pdb-skip >*/
+{
+  GIMP_GRAVITY_NONE,
+  GIMP_GRAVITY_NORTH_WEST,
+  GIMP_GRAVITY_NORTH,
+  GIMP_GRAVITY_NORTH_EAST,
+  GIMP_GRAVITY_WEST,
+  GIMP_GRAVITY_CENTER,
+  GIMP_GRAVITY_EAST,
+  GIMP_GRAVITY_SOUTH_WEST,
+  GIMP_GRAVITY_SOUTH,
+  GIMP_GRAVITY_SOUTH_EAST
+} GimpGravityType;
+
+
+#define GIMP_TYPE_GUIDE_STYLE (gimp_guide_style_get_type ())
+
+GType gimp_guide_style_get_type (void) G_GNUC_CONST;
+
+typedef enum /*< pdb-skip >*/
+{
+  GIMP_GUIDE_STYLE_NONE,
+  GIMP_GUIDE_STYLE_NORMAL,
+  GIMP_GUIDE_STYLE_MIRROR,
+  GIMP_GUIDE_STYLE_MANDALA,
+  GIMP_GUIDE_STYLE_SPLIT_VIEW
+} GimpGuideStyle;
+
+
+#define GIMP_TYPE_HISTOGRAM_CHANNEL (gimp_histogram_channel_get_type ())
+
+GType gimp_histogram_channel_get_type (void) G_GNUC_CONST;
+
+typedef enum
+{
+  GIMP_HISTOGRAM_VALUE     = 0,  /*< desc="Value"         >*/
+  GIMP_HISTOGRAM_RED       = 1,  /*< desc="Red"           >*/
+  GIMP_HISTOGRAM_GREEN     = 2,  /*< desc="Green"         >*/
+  GIMP_HISTOGRAM_BLUE      = 3,  /*< desc="Blue"          >*/
+  GIMP_HISTOGRAM_ALPHA     = 4,  /*< desc="Alpha"         >*/
+  GIMP_HISTOGRAM_LUMINANCE = 5,  /*< desc="Luminance"     >*/
+  GIMP_HISTOGRAM_RGB       = 6   /*< desc="RGB", pdb-skip >*/
+} GimpHistogramChannel;
+
+
+#define GIMP_TYPE_ITEM_SET (gimp_item_set_get_type ())
+
+GType gimp_item_set_get_type (void) G_GNUC_CONST;
+
+typedef enum  /*< pdb-skip >*/
+{
+  GIMP_ITEM_SET_NONE,        /*< desc="None"               >*/
+  GIMP_ITEM_SET_ALL,         /*< desc="All layers"         >*/
+  GIMP_ITEM_SET_IMAGE_SIZED, /*< desc="Image-sized layers" >*/
+  GIMP_ITEM_SET_VISIBLE,     /*< desc="All visible layers" >*/
+  GIMP_ITEM_SET_LINKED       /*< desc="All linked layers"  >*/
+} GimpItemSet;
+
+
+#define GIMP_TYPE_MATTING_ENGINE (gimp_matting_engine_get_type ())
+
+GType gimp_matting_engine_get_type (void) G_GNUC_CONST;
+
+typedef enum  /*< pdb-skip >*/
+{
+  GIMP_MATTING_ENGINE_GLOBAL,  /*< desc="Matting Global" >*/
+  GIMP_MATTING_ENGINE_LEVIN,   /*< desc="Matting Levin" >*/
+} GimpMattingEngine;
+
+
+#define GIMP_TYPE_MESSAGE_SEVERITY (gimp_message_severity_get_type ())
+
+GType gimp_message_severity_get_type (void) G_GNUC_CONST;
+
+typedef enum  /*< pdb-skip >*/
+{
+  GIMP_MESSAGE_INFO,        /*< desc="Message"  >*/
+  GIMP_MESSAGE_WARNING,     /*< desc="Warning"  >*/
+  GIMP_MESSAGE_ERROR,       /*< desc="Error"    >*/
+  GIMP_MESSAGE_BUG_WARNING, /*< desc="WARNING"  >*/
+  GIMP_MESSAGE_BUG_CRITICAL /*< desc="CRITICAL" >*/
+} GimpMessageSeverity;
+
+
+#define GIMP_TYPE_PASTE_TYPE (gimp_paste_type_get_type ())
+
+GType gimp_paste_type_get_type (void) G_GNUC_CONST;
+
+typedef enum  /*< pdb-skip >*/
+{
+  GIMP_PASTE_TYPE_FLOATING,
+  GIMP_PASTE_TYPE_FLOATING_IN_PLACE,
+  GIMP_PASTE_TYPE_FLOATING_INTO,
+  GIMP_PASTE_TYPE_FLOATING_INTO_IN_PLACE,
+  GIMP_PASTE_TYPE_NEW_LAYER,
+  GIMP_PASTE_TYPE_NEW_LAYER_IN_PLACE
+} GimpPasteType;
+
+
+#define GIMP_TYPE_THUMBNAIL_SIZE (gimp_thumbnail_size_get_type ())
+
+GType gimp_thumbnail_size_get_type (void) G_GNUC_CONST;
+
+typedef enum  /*< pdb-skip >*/
+{
+  GIMP_THUMBNAIL_SIZE_NONE    = 0,    /*< desc="No thumbnails"    >*/
+  GIMP_THUMBNAIL_SIZE_NORMAL  = 128,  /*< desc="Normal (128x128)" >*/
+  GIMP_THUMBNAIL_SIZE_LARGE   = 256   /*< desc="Large (256x256)"  >*/
+} GimpThumbnailSize;
+
+
+#define GIMP_TYPE_UNDO_EVENT (gimp_undo_event_get_type ())
+
+GType gimp_undo_event_get_type (void) G_GNUC_CONST;
+
+typedef enum  /*< pdb-skip >*/
+{
+  GIMP_UNDO_EVENT_UNDO_PUSHED,  /* a new undo has been added to the undo stack */
+  GIMP_UNDO_EVENT_UNDO_EXPIRED, /* an undo has been freed from the undo stack  */
+  GIMP_UNDO_EVENT_REDO_EXPIRED, /* a redo has been freed from the redo stack   */
+  GIMP_UNDO_EVENT_UNDO,         /* an undo has been executed                   */
+  GIMP_UNDO_EVENT_REDO,         /* a redo has been executed                    */
+  GIMP_UNDO_EVENT_UNDO_FREE,    /* all undo and redo info has been cleared     */
+  GIMP_UNDO_EVENT_UNDO_FREEZE,  /* undo has been frozen                        */
+  GIMP_UNDO_EVENT_UNDO_THAW     /* undo has been thawn                         */
+} GimpUndoEvent;
+
+
+#define GIMP_TYPE_UNDO_MODE (gimp_undo_mode_get_type ())
+
+GType gimp_undo_mode_get_type (void) G_GNUC_CONST;
+
+typedef enum /*< pdb-skip >*/
+{
+  GIMP_UNDO_MODE_UNDO,
+  GIMP_UNDO_MODE_REDO
+} GimpUndoMode;
+
+
+#define GIMP_TYPE_UNDO_TYPE (gimp_undo_type_get_type ())
+
+GType gimp_undo_type_get_type (void) G_GNUC_CONST;
+
+typedef enum /*< pdb-skip >*/
+{
+  /* Type NO_UNDO_GROUP (0) is special - in the gimpimage structure it
+   * means there is no undo group currently being added to.
+   */
+  GIMP_UNDO_GROUP_NONE = 0,              /*< desc="<<invalid>>"                    >*/
+
+  GIMP_UNDO_GROUP_FIRST = GIMP_UNDO_GROUP_NONE, /*< skip >*/
+
+  GIMP_UNDO_GROUP_IMAGE_SCALE,           /*< desc="Scale image"                    >*/
+  GIMP_UNDO_GROUP_IMAGE_RESIZE,          /*< desc="Resize image"                   >*/
+  GIMP_UNDO_GROUP_IMAGE_FLIP,            /*< desc="Flip image"                     >*/
+  GIMP_UNDO_GROUP_IMAGE_ROTATE,          /*< desc="Rotate image"                   >*/
+  GIMP_UNDO_GROUP_IMAGE_TRANSFORM,       /*< desc="Transform image"                >*/
+  GIMP_UNDO_GROUP_IMAGE_CROP,            /*< desc="Crop image"                     >*/
+  GIMP_UNDO_GROUP_IMAGE_CONVERT,         /*< desc="Convert image"                  >*/
+  GIMP_UNDO_GROUP_IMAGE_ITEM_REMOVE,     /*< desc="Remove item"                    >*/
+  GIMP_UNDO_GROUP_IMAGE_ITEM_REORDER,    /*< desc="Reorder item"                   >*/
+  GIMP_UNDO_GROUP_IMAGE_LAYERS_MERGE,    /*< desc="Merge layers"                   >*/
+  GIMP_UNDO_GROUP_IMAGE_VECTORS_MERGE,   /*< desc="Merge paths"                    >*/
+  GIMP_UNDO_GROUP_IMAGE_QUICK_MASK,      /*< desc="Quick Mask"                     >*/
+  GIMP_UNDO_GROUP_IMAGE_GRID,            /*< desc="Grid"                           >*/
+  GIMP_UNDO_GROUP_GUIDE,                 /*< desc="Guide"                          >*/
+  GIMP_UNDO_GROUP_SAMPLE_POINT,          /*< desc="Sample Point"                   >*/
+  GIMP_UNDO_GROUP_DRAWABLE,              /*< desc="Layer/Channel"                  >*/
+  GIMP_UNDO_GROUP_DRAWABLE_MOD,          /*< desc="Layer/Channel modification"     >*/
+  GIMP_UNDO_GROUP_MASK,                  /*< desc="Selection mask"                 >*/
+  GIMP_UNDO_GROUP_ITEM_VISIBILITY,       /*< desc="Item visibility"                >*/
+  GIMP_UNDO_GROUP_ITEM_LINKED,           /*< desc="Link/Unlink item"               >*/
+  GIMP_UNDO_GROUP_ITEM_PROPERTIES,       /*< desc="Item properties"                >*/
+  GIMP_UNDO_GROUP_ITEM_DISPLACE,         /*< desc="Move item"                      >*/
+  GIMP_UNDO_GROUP_ITEM_SCALE,            /*< desc="Scale item"                     >*/
+  GIMP_UNDO_GROUP_ITEM_RESIZE,           /*< desc="Resize item"                    >*/
+  GIMP_UNDO_GROUP_LAYER_ADD,             /*< desc="Add layer"                      >*/
+  GIMP_UNDO_GROUP_LAYER_ADD_MASK,        /*< desc="Add layer mask"                 >*/
+  GIMP_UNDO_GROUP_LAYER_APPLY_MASK,      /*< desc="Apply layer mask"               >*/
+  GIMP_UNDO_GROUP_FS_TO_LAYER,           /*< desc="Floating selection to layer"    >*/
+  GIMP_UNDO_GROUP_FS_FLOAT,              /*< desc="Float selection"                >*/
+  GIMP_UNDO_GROUP_FS_ANCHOR,             /*< desc="Anchor floating selection"      >*/
+  GIMP_UNDO_GROUP_EDIT_PASTE,            /*< desc="Paste"                          >*/
+  GIMP_UNDO_GROUP_EDIT_CUT,              /*< desc="Cut"                            >*/
+  GIMP_UNDO_GROUP_TEXT,                  /*< desc="Text"                           >*/
+  GIMP_UNDO_GROUP_TRANSFORM,             /*< desc="Transform"                      >*/
+  GIMP_UNDO_GROUP_PAINT,                 /*< desc="Paint"                          >*/
+  GIMP_UNDO_GROUP_PARASITE_ATTACH,       /*< desc="Attach parasite"                >*/
+  GIMP_UNDO_GROUP_PARASITE_REMOVE,       /*< desc="Remove parasite"                >*/
+  GIMP_UNDO_GROUP_VECTORS_IMPORT,        /*< desc="Import paths"                   >*/
+  GIMP_UNDO_GROUP_MISC,                  /*< desc="Plug-In"                        >*/
+
+  GIMP_UNDO_GROUP_LAST = GIMP_UNDO_GROUP_MISC, /*< skip >*/
+
+  /*  Undo types which actually do something  */
+
+  GIMP_UNDO_IMAGE_TYPE,                  /*< desc="Image type"                     >*/
+  GIMP_UNDO_IMAGE_PRECISION,             /*< desc="Image precision"                >*/
+  GIMP_UNDO_IMAGE_SIZE,                  /*< desc="Image size"                     >*/
+  GIMP_UNDO_IMAGE_RESOLUTION,            /*< desc="Image resolution change"        >*/
+  GIMP_UNDO_IMAGE_GRID,                  /*< desc="Grid"                           >*/
+  GIMP_UNDO_IMAGE_METADATA,              /*< desc="Change metadata"                >*/
+  GIMP_UNDO_IMAGE_COLORMAP,              /*< desc="Change indexed palette"         >*/
+  GIMP_UNDO_IMAGE_COLOR_MANAGED,         /*< desc="Change color managed state"     >*/
+  GIMP_UNDO_GUIDE,                       /*< desc="Guide"                          >*/
+  GIMP_UNDO_SAMPLE_POINT,                /*< desc="Sample Point"                   >*/
+  GIMP_UNDO_DRAWABLE,                    /*< desc="Layer/Channel"                  >*/
+  GIMP_UNDO_DRAWABLE_MOD,                /*< desc="Layer/Channel modification"     >*/
+  GIMP_UNDO_MASK,                        /*< desc="Selection mask"                 >*/
+  GIMP_UNDO_ITEM_REORDER,                /*< desc="Reorder item"                   >*/
+  GIMP_UNDO_ITEM_RENAME,                 /*< desc="Rename item"                    >*/
+  GIMP_UNDO_ITEM_DISPLACE,               /*< desc="Move item"                      >*/
+  GIMP_UNDO_ITEM_VISIBILITY,             /*< desc="Item visibility"                >*/
+  GIMP_UNDO_ITEM_LINKED,                 /*< desc="Link/Unlink item"               >*/
+  GIMP_UNDO_ITEM_COLOR_TAG,              /*< desc="Item color tag"                 >*/
+  GIMP_UNDO_ITEM_LOCK_CONTENT,           /*< desc="Lock/Unlock content"            >*/
+  GIMP_UNDO_ITEM_LOCK_POSITION,          /*< desc="Lock/Unlock position"           >*/
+  GIMP_UNDO_LAYER_ADD,                   /*< desc="New layer"                      >*/
+  GIMP_UNDO_LAYER_REMOVE,                /*< desc="Delete layer"                   >*/
+  GIMP_UNDO_LAYER_MODE,                  /*< desc="Set layer mode"                 >*/
+  GIMP_UNDO_LAYER_OPACITY,               /*< desc="Set layer opacity"              >*/
+  GIMP_UNDO_LAYER_LOCK_ALPHA,            /*< desc="Lock/Unlock alpha channel"      >*/
+  GIMP_UNDO_GROUP_LAYER_SUSPEND_RESIZE,  /*< desc="Suspend group layer resize"     >*/
+  GIMP_UNDO_GROUP_LAYER_RESUME_RESIZE,   /*< desc="Resume group layer resize"      >*/
+  GIMP_UNDO_GROUP_LAYER_SUSPEND_MASK,    /*< desc="Suspend group layer mask"       >*/
+  GIMP_UNDO_GROUP_LAYER_RESUME_MASK,     /*< desc="Resume group layer mask"        >*/
+  GIMP_UNDO_GROUP_LAYER_START_TRANSFORM, /*< desc="Start transforming group layer" >*/
+  GIMP_UNDO_GROUP_LAYER_END_TRANSFORM,   /*< desc="End transforming group layer"   >*/
+  GIMP_UNDO_GROUP_LAYER_CONVERT,         /*< desc="Convert group layer"            >*/
+  GIMP_UNDO_TEXT_LAYER,                  /*< desc="Text layer"                     >*/
+  GIMP_UNDO_TEXT_LAYER_MODIFIED,         /*< desc="Text layer modification"        >*/
+  GIMP_UNDO_TEXT_LAYER_CONVERT,          /*< desc="Convert text layer"             >*/
+  GIMP_UNDO_LAYER_MASK_ADD,              /*< desc="Add layer mask"                 >*/
+  GIMP_UNDO_LAYER_MASK_REMOVE,           /*< desc="Delete layer mask"              >*/
+  GIMP_UNDO_LAYER_MASK_APPLY,            /*< desc="Apply layer mask"               >*/
+  GIMP_UNDO_LAYER_MASK_SHOW,             /*< desc="Show layer mask"                >*/
+  GIMP_UNDO_CHANNEL_ADD,                 /*< desc="New channel"                    >*/
+  GIMP_UNDO_CHANNEL_REMOVE,              /*< desc="Delete channel"                 >*/
+  GIMP_UNDO_CHANNEL_COLOR,               /*< desc="Channel color"                  >*/
+  GIMP_UNDO_VECTORS_ADD,                 /*< desc="New path"                       >*/
+  GIMP_UNDO_VECTORS_REMOVE,              /*< desc="Delete path"                    >*/
+  GIMP_UNDO_VECTORS_MOD,                 /*< desc="Path modification"              >*/
+  GIMP_UNDO_FS_TO_LAYER,                 /*< desc="Floating selection to layer"    >*/
+  GIMP_UNDO_TRANSFORM_GRID,              /*< desc="Transform grid"                 >*/
+  GIMP_UNDO_PAINT,                       /*< desc="Paint"                          >*/
+  GIMP_UNDO_INK,                         /*< desc="Ink"                            >*/
+  GIMP_UNDO_FOREGROUND_SELECT,           /*< desc="Select foreground"              >*/
+  GIMP_UNDO_PARASITE_ATTACH,             /*< desc="Attach parasite"                >*/
+  GIMP_UNDO_PARASITE_REMOVE,             /*< desc="Remove parasite"                >*/
+
+  GIMP_UNDO_CANT                         /*< desc="Not undoable"                   >*/
+} GimpUndoType;
+
+
+#define GIMP_TYPE_VIEW_SIZE (gimp_view_size_get_type ())
+
+GType gimp_view_size_get_type (void) G_GNUC_CONST;
+
+typedef enum  /*< pdb-skip >*/
+{
+  GIMP_VIEW_SIZE_TINY        = 12,   /*< desc="Tiny"        >*/
+  GIMP_VIEW_SIZE_EXTRA_SMALL = 16,   /*< desc="Very small"  >*/
+  GIMP_VIEW_SIZE_SMALL       = 24,   /*< desc="Small"       >*/
+  GIMP_VIEW_SIZE_MEDIUM      = 32,   /*< desc="Medium"      >*/
+  GIMP_VIEW_SIZE_LARGE       = 48,   /*< desc="Large"       >*/
+  GIMP_VIEW_SIZE_EXTRA_LARGE = 64,   /*< desc="Very large"  >*/
+  GIMP_VIEW_SIZE_HUGE        = 96,   /*< desc="Huge"        >*/
+  GIMP_VIEW_SIZE_ENORMOUS    = 128,  /*< desc="Enormous"    >*/
+  GIMP_VIEW_SIZE_GIGANTIC    = 192   /*< desc="Gigantic"    >*/
+} GimpViewSize;
+
+
+#define GIMP_TYPE_VIEW_TYPE (gimp_view_type_get_type ())
+
+GType gimp_view_type_get_type (void) G_GNUC_CONST;
+
+typedef enum  /*< pdb-skip >*/
+{
+  GIMP_VIEW_TYPE_LIST,  /*< desc="View as list" >*/
+  GIMP_VIEW_TYPE_GRID   /*< desc="View as grid" >*/
+} GimpViewType;
+
+
+/*
+ * non-registered enums; register them if needed
+ */
+
+
+typedef enum  /*< pdb-skip, skip >*/
+{
+  GIMP_CONTEXT_PROP_FIRST       =  2,
+
+  GIMP_CONTEXT_PROP_IMAGE       =  GIMP_CONTEXT_PROP_FIRST,
+  GIMP_CONTEXT_PROP_DISPLAY     =  3,
+  GIMP_CONTEXT_PROP_TOOL        =  4,
+  GIMP_CONTEXT_PROP_PAINT_INFO  =  5,
+  GIMP_CONTEXT_PROP_FOREGROUND  =  6,
+  GIMP_CONTEXT_PROP_BACKGROUND  =  7,
+  GIMP_CONTEXT_PROP_OPACITY     =  8,
+  GIMP_CONTEXT_PROP_PAINT_MODE  =  9,
+  GIMP_CONTEXT_PROP_BRUSH       = 10,
+  GIMP_CONTEXT_PROP_DYNAMICS    = 11,
+  GIMP_CONTEXT_PROP_MYBRUSH     = 12,
+  GIMP_CONTEXT_PROP_PATTERN     = 13,
+  GIMP_CONTEXT_PROP_GRADIENT    = 14,
+  GIMP_CONTEXT_PROP_PALETTE     = 15,
+  GIMP_CONTEXT_PROP_FONT        = 16,
+  GIMP_CONTEXT_PROP_TOOL_PRESET = 17,
+  GIMP_CONTEXT_PROP_BUFFER      = 18,
+  GIMP_CONTEXT_PROP_IMAGEFILE   = 19,
+  GIMP_CONTEXT_PROP_TEMPLATE    = 20,
+
+  GIMP_CONTEXT_PROP_LAST        = GIMP_CONTEXT_PROP_TEMPLATE
+} GimpContextPropType;
+
+
+typedef enum  /*< pdb-skip, skip >*/
+{
+  GIMP_CONTEXT_PROP_MASK_IMAGE       = 1 <<  2,
+  GIMP_CONTEXT_PROP_MASK_DISPLAY     = 1 <<  3,
+  GIMP_CONTEXT_PROP_MASK_TOOL        = 1 <<  4,
+  GIMP_CONTEXT_PROP_MASK_PAINT_INFO  = 1 <<  5,
+  GIMP_CONTEXT_PROP_MASK_FOREGROUND  = 1 <<  6,
+  GIMP_CONTEXT_PROP_MASK_BACKGROUND  = 1 <<  7,
+  GIMP_CONTEXT_PROP_MASK_OPACITY     = 1 <<  8,
+  GIMP_CONTEXT_PROP_MASK_PAINT_MODE  = 1 <<  9,
+  GIMP_CONTEXT_PROP_MASK_BRUSH       = 1 << 10,
+  GIMP_CONTEXT_PROP_MASK_DYNAMICS    = 1 << 11,
+  GIMP_CONTEXT_PROP_MASK_MYBRUSH     = 1 << 12,
+  GIMP_CONTEXT_PROP_MASK_PATTERN     = 1 << 13,
+  GIMP_CONTEXT_PROP_MASK_GRADIENT    = 1 << 14,
+  GIMP_CONTEXT_PROP_MASK_PALETTE     = 1 << 15,
+  GIMP_CONTEXT_PROP_MASK_FONT        = 1 << 16,
+  GIMP_CONTEXT_PROP_MASK_TOOL_PRESET = 1 << 17,
+  GIMP_CONTEXT_PROP_MASK_BUFFER      = 1 << 18,
+  GIMP_CONTEXT_PROP_MASK_IMAGEFILE   = 1 << 19,
+  GIMP_CONTEXT_PROP_MASK_TEMPLATE    = 1 << 20,
+
+  /*  aliases  */
+  GIMP_CONTEXT_PROP_MASK_PAINT = (GIMP_CONTEXT_PROP_MASK_FOREGROUND |
+                                  GIMP_CONTEXT_PROP_MASK_BACKGROUND |
+                                  GIMP_CONTEXT_PROP_MASK_OPACITY    |
+                                  GIMP_CONTEXT_PROP_MASK_PAINT_MODE |
+                                  GIMP_CONTEXT_PROP_MASK_BRUSH      |
+                                  GIMP_CONTEXT_PROP_MASK_DYNAMICS   |
+                                  GIMP_CONTEXT_PROP_MASK_PATTERN    |
+                                  GIMP_CONTEXT_PROP_MASK_GRADIENT),
+
+  GIMP_CONTEXT_PROP_MASK_ALL   = (GIMP_CONTEXT_PROP_MASK_IMAGE       |
+                                  GIMP_CONTEXT_PROP_MASK_DISPLAY     |
+                                  GIMP_CONTEXT_PROP_MASK_TOOL        |
+                                  GIMP_CONTEXT_PROP_MASK_PAINT_INFO  |
+                                  GIMP_CONTEXT_PROP_MASK_MYBRUSH     |
+                                  GIMP_CONTEXT_PROP_MASK_PALETTE     |
+                                  GIMP_CONTEXT_PROP_MASK_FONT        |
+                                  GIMP_CONTEXT_PROP_MASK_TOOL_PRESET |
+                                  GIMP_CONTEXT_PROP_MASK_BUFFER      |
+                                  GIMP_CONTEXT_PROP_MASK_IMAGEFILE   |
+                                  GIMP_CONTEXT_PROP_MASK_TEMPLATE    |
+                                  GIMP_CONTEXT_PROP_MASK_PAINT)
+} GimpContextPropMask;
+
+
+typedef enum  /*< pdb-skip, skip >*/
+{
+  GIMP_IMAGE_SCALE_OK,
+  GIMP_IMAGE_SCALE_TOO_SMALL,
+  GIMP_IMAGE_SCALE_TOO_BIG
+} GimpImageScaleCheckType;
+
+
+typedef enum  /*< pdb-skip, skip >*/
+{
+  GIMP_ITEM_TYPE_LAYERS   = 1 << 0,
+  GIMP_ITEM_TYPE_CHANNELS = 1 << 1,
+  GIMP_ITEM_TYPE_VECTORS  = 1 << 2,
+
+  GIMP_ITEM_TYPE_ALL      = (GIMP_ITEM_TYPE_LAYERS   |
+                             GIMP_ITEM_TYPE_CHANNELS |
+                             GIMP_ITEM_TYPE_VECTORS)
+} GimpItemTypeMask;
+
+
+#endif /* __CORE_ENUMS_H__ */
diff --git a/app/core/core-types.h b/app/core/core-types.h
new file mode 100644
index 0000000..bc331b4
--- /dev/null
+++ b/app/core/core-types.h
@@ -0,0 +1,303 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __CORE_TYPES_H__
+#define __CORE_TYPES_H__
+
+
+#include "libgimpbase/gimpbasetypes.h"
+#include "libgimpmath/gimpmathtypes.h"
+#include "libgimpcolor/gimpcolortypes.h"
+#include "libgimpmodule/gimpmoduletypes.h"
+#include "libgimpthumb/gimpthumb-types.h"
+
+#include "config/config-types.h"
+
+#include "core/core-enums.h"
+
+
+/*  former base/ defines  */
+
+#define MAX_CHANNELS  4
+
+#define RED           0
+#define GREEN         1
+#define BLUE          2
+#define ALPHA         3
+
+#define GRAY          0
+#define ALPHA_G       1
+
+#define INDEXED       0
+#define ALPHA_I       1
+
+
+/*  defines  */
+
+#define GIMP_COORDS_MIN_PRESSURE      0.0
+#define GIMP_COORDS_MAX_PRESSURE      1.0
+#define GIMP_COORDS_DEFAULT_PRESSURE  1.0
+
+#define GIMP_COORDS_MIN_TILT         -1.0
+#define GIMP_COORDS_MAX_TILT          1.0
+#define GIMP_COORDS_DEFAULT_TILT      0.0
+
+#define GIMP_COORDS_MIN_WHEEL         0.0
+#define GIMP_COORDS_MAX_WHEEL         1.0
+#define GIMP_COORDS_DEFAULT_WHEEL     0.5
+
+#define GIMP_COORDS_DEFAULT_VELOCITY  0.0
+
+#define GIMP_COORDS_DEFAULT_DIRECTION 0.0
+
+#define GIMP_COORDS_DEFAULT_XSCALE    1.0
+#define GIMP_COORDS_DEFAULT_YSCALE    1.0
+
+#define GIMP_COORDS_DEFAULT_VALUES    { 0.0, 0.0, \
+                                        GIMP_COORDS_DEFAULT_PRESSURE, \
+                                        GIMP_COORDS_DEFAULT_TILT,     \
+                                        GIMP_COORDS_DEFAULT_TILT,     \
+                                        GIMP_COORDS_DEFAULT_WHEEL,    \
+                                        GIMP_COORDS_DEFAULT_VELOCITY, \
+                                        GIMP_COORDS_DEFAULT_DIRECTION,\
+                                        GIMP_COORDS_DEFAULT_XSCALE,   \
+                                        GIMP_COORDS_DEFAULT_YSCALE }
+
+
+/*  base classes  */
+
+typedef struct _GimpObject                      GimpObject;
+typedef struct _GimpViewable                    GimpViewable;
+typedef struct _GimpFilter                      GimpFilter;
+typedef struct _GimpItem                        GimpItem;
+typedef struct _GimpAuxItem                     GimpAuxItem;
+
+typedef struct _Gimp                            Gimp;
+typedef struct _GimpImage                       GimpImage;
+
+
+/*  containers  */
+
+typedef struct _GimpContainer                   GimpContainer;
+typedef struct _GimpList                        GimpList;
+typedef struct _GimpDocumentList                GimpDocumentList;
+typedef struct _GimpDrawableStack               GimpDrawableStack;
+typedef struct _GimpFilteredContainer           GimpFilteredContainer;
+typedef struct _GimpFilterStack                 GimpFilterStack;
+typedef struct _GimpItemStack                   GimpItemStack;
+typedef struct _GimpLayerStack                  GimpLayerStack;
+typedef struct _GimpTaggedContainer             GimpTaggedContainer;
+typedef struct _GimpTreeProxy                   GimpTreeProxy;
+
+
+/*  not really a container  */
+
+typedef struct _GimpItemTree                    GimpItemTree;
+
+
+/*  context objects  */
+
+typedef struct _GimpContext                     GimpContext;
+typedef struct _GimpFillOptions                 GimpFillOptions;
+typedef struct _GimpStrokeOptions               GimpStrokeOptions;
+typedef struct _GimpToolOptions                 GimpToolOptions;
+
+
+/*  info objects  */
+
+typedef struct _GimpPaintInfo                   GimpPaintInfo;
+typedef struct _GimpToolGroup                   GimpToolGroup;
+typedef struct _GimpToolInfo                    GimpToolInfo;
+typedef struct _GimpToolItem                    GimpToolItem;
+
+
+/*  data objects  */
+
+typedef struct _GimpDataFactory                 GimpDataFactory;
+typedef struct _GimpDataLoaderFactory           GimpDataLoaderFactory;
+typedef struct _GimpData                        GimpData;
+typedef struct _GimpBrush                       GimpBrush;
+typedef struct _GimpBrushCache                  GimpBrushCache;
+typedef struct _GimpBrushClipboard              GimpBrushClipboard;
+typedef struct _GimpBrushGenerated              GimpBrushGenerated;
+typedef struct _GimpBrushPipe                   GimpBrushPipe;
+typedef struct _GimpCurve                       GimpCurve;
+typedef struct _GimpDynamics                    GimpDynamics;
+typedef struct _GimpDynamicsOutput              GimpDynamicsOutput;
+typedef struct _GimpGradient                    GimpGradient;
+typedef struct _GimpMybrush                     GimpMybrush;
+typedef struct _GimpPalette                     GimpPalette;
+typedef struct _GimpPaletteMru                  GimpPaletteMru;
+typedef struct _GimpPattern                     GimpPattern;
+typedef struct _GimpPatternClipboard            GimpPatternClipboard;
+typedef struct _GimpToolPreset                  GimpToolPreset;
+typedef struct _GimpTagCache                    GimpTagCache;
+
+
+/*  drawable objects  */
+
+typedef struct _GimpDrawable                    GimpDrawable;
+typedef struct _GimpChannel                     GimpChannel;
+typedef struct _GimpLayerMask                   GimpLayerMask;
+typedef struct _GimpSelection                   GimpSelection;
+typedef struct _GimpLayer                       GimpLayer;
+typedef struct _GimpGroupLayer                  GimpGroupLayer;
+
+
+/*  auxillary image items  */
+
+typedef struct _GimpGuide                       GimpGuide;
+typedef struct _GimpSamplePoint                 GimpSamplePoint;
+
+
+/*  undo objects  */
+
+typedef struct _GimpUndo                        GimpUndo;
+typedef struct _GimpUndoStack                   GimpUndoStack;
+typedef struct _GimpUndoAccumulator             GimpUndoAccumulator;
+
+
+/* Symmetry transformations */
+
+typedef struct _GimpSymmetry                    GimpSymmetry;
+typedef struct _GimpMirror                      GimpMirror;
+typedef struct _GimpTiling                      GimpTiling;
+typedef struct _GimpMandala                     GimpMandala;
+
+
+/*  misc objects  */
+
+typedef struct _GimpAsync                       GimpAsync;
+typedef struct _GimpAsyncSet                    GimpAsyncSet;
+typedef struct _GimpBuffer                      GimpBuffer;
+typedef struct _GimpDrawableFilter              GimpDrawableFilter;
+typedef struct _GimpEnvironTable                GimpEnvironTable;
+typedef struct _GimpHistogram                   GimpHistogram;
+typedef struct _GimpIdTable                     GimpIdTable;
+typedef struct _GimpImagefile                   GimpImagefile;
+typedef struct _GimpImageProxy                  GimpImageProxy;
+typedef struct _GimpInterpreterDB               GimpInterpreterDB;
+typedef struct _GimpLineArt                     GimpLineArt;
+typedef struct _GimpObjectQueue                 GimpObjectQueue;
+typedef struct _GimpParasiteList                GimpParasiteList;
+typedef struct _GimpPdbProgress                 GimpPdbProgress;
+typedef struct _GimpProjection                  GimpProjection;
+typedef struct _GimpSettings                    GimpSettings;
+typedef struct _GimpSubProgress                 GimpSubProgress;
+typedef struct _GimpTag                         GimpTag;
+typedef struct _GimpTreeHandler                 GimpTreeHandler;
+typedef struct _GimpTriviallyCancelableWaitable GimpTriviallyCancelableWaitable;
+typedef struct _GimpUncancelableWaitable        GimpUncancelableWaitable;
+
+
+/*  interfaces  */
+
+typedef struct _GimpCancelable                  GimpCancelable;  /* dummy typedef */
+typedef struct _GimpPickable                    GimpPickable;    /* dummy typedef */
+typedef struct _GimpProgress                    GimpProgress;    /* dummy typedef */
+typedef struct _GimpProjectable                 GimpProjectable; /* dummy typedef */
+typedef struct _GimpTagged                      GimpTagged;      /* dummy typedef */
+typedef struct _GimpWaitable                    GimpWaitable;    /* dummy typedef */
+
+
+/*  non-object types  */
+
+typedef struct _GimpBacktrace                   GimpBacktrace;
+typedef struct _GimpBoundSeg                    GimpBoundSeg;
+typedef struct _GimpChunkIterator               GimpChunkIterator;
+typedef struct _GimpCoords                      GimpCoords;
+typedef struct _GimpGradientSegment             GimpGradientSegment;
+typedef struct _GimpPaletteEntry                GimpPaletteEntry;
+typedef struct _GimpScanConvert                 GimpScanConvert;
+typedef struct _GimpTempBuf                     GimpTempBuf;
+typedef         guint32                         GimpTattoo;
+
+/* The following hack is made so that we can reuse the definition
+ * the cairo definition of cairo_path_t without having to translate
+ * between our own version of a bezier description and cairos version.
+ *
+ * to avoid having to include <cairo.h> in each and every file
+ * including this file we only use the "real" definition when cairo.h
+ * already has been included and use something else.
+ *
+ * Note that if you really want to work with GimpBezierDesc (except just
+ * passing pointers to it around) you also need to include <cairo.h>.
+ */
+#ifdef CAIRO_VERSION
+typedef cairo_path_t GimpBezierDesc;
+#else
+typedef void * GimpBezierDesc;
+#endif
+
+
+/*  functions  */
+
+typedef void     (* GimpInitStatusFunc)    (const gchar *text1,
+                                            const gchar *text2,
+                                            gdouble      percentage);
+
+typedef gboolean (* GimpObjectFilterFunc)  (GimpObject  *object,
+                                            gpointer     user_data);
+
+typedef gint64   (* GimpMemsizeFunc)       (gpointer     instance,
+                                            gint64      *gui_size);
+
+typedef void     (* GimpRunAsyncFunc)      (GimpAsync   *async,
+                                            gpointer     user_data);
+
+
+/*  structs  */
+
+struct _GimpCoords
+{
+  gdouble  x;
+  gdouble  y;
+  gdouble  pressure;
+  gdouble  xtilt;
+  gdouble  ytilt;
+  gdouble  wheel;
+  gdouble  velocity;
+  gdouble  direction;
+  gdouble  xscale;  /* the view scale                */
+  gdouble  yscale;
+  gdouble  angle;   /* the view rotation angle       */
+  gboolean reflect; /* whether the view is reflected */
+  gboolean extended;
+};
+
+/*  temp hack as replacement for GdkSegment  */
+
+typedef struct _GimpSegment GimpSegment;
+
+struct _GimpSegment
+{
+  gint x1;
+  gint y1;
+  gint x2;
+  gint y2;
+};
+
+
+#include "gegl/gimp-gegl-types.h"
+#include "paint/paint-types.h"
+#include "text/text-types.h"
+#include "vectors/vectors-types.h"
+#include "pdb/pdb-types.h"
+#include "plug-in/plug-in-types.h"
+
+
+#endif /* __CORE_TYPES_H__ */
diff --git a/app/core/gimp-atomic.c b/app/core/gimp-atomic.c
new file mode 100644
index 0000000..c5a54b8
--- /dev/null
+++ b/app/core/gimp-atomic.c
@@ -0,0 +1,95 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimp-atomic.c
+ * Copyright (C) 2018 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gimp-atomic.h"
+
+
+/*  GSList  */
+
+
+static GSList gimp_atomic_slist_sentinel;
+
+
+void
+gimp_atomic_slist_push_head (GSList   * volatile *list,
+                             gpointer             data)
+{
+  GSList *old_head;
+  GSList *new_head;
+
+  g_return_if_fail (list != NULL);
+
+  new_head = g_slist_alloc ();
+
+  new_head->data = data;
+
+  do
+    {
+      do
+        {
+          old_head = g_atomic_pointer_get (list);
+        }
+      while (old_head == &gimp_atomic_slist_sentinel);
+
+      new_head->next = old_head;
+    }
+  while (! g_atomic_pointer_compare_and_exchange (list, old_head, new_head));
+}
+
+gpointer
+gimp_atomic_slist_pop_head (GSList * volatile *list)
+{
+  GSList   *old_head;
+  GSList   *new_head;
+  gpointer  data;
+
+  g_return_val_if_fail (list != NULL, NULL);
+
+  do
+    {
+      do
+        {
+          old_head = g_atomic_pointer_get (list);
+        }
+      while (old_head == &gimp_atomic_slist_sentinel);
+
+      if (! old_head)
+        return NULL;
+    }
+  while (! g_atomic_pointer_compare_and_exchange (list,
+                                                  old_head,
+                                                  &gimp_atomic_slist_sentinel));
+
+  new_head = old_head->next;
+  data     = old_head->data;
+
+  g_atomic_pointer_set (list, new_head);
+
+  g_slist_free1 (old_head);
+
+  return data;
+}
diff --git a/app/core/gimp-atomic.h b/app/core/gimp-atomic.h
new file mode 100644
index 0000000..c1d71cc
--- /dev/null
+++ b/app/core/gimp-atomic.h
@@ -0,0 +1,32 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimp-atomic.h
+ * Copyright (C) 2018 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_ATOMIC_H__
+#define __GIMP_ATOMIC_H__
+
+
+/*  GSList  */
+
+void       gimp_atomic_slist_push_head (GSList   * volatile *list,
+                                        gpointer             data);
+gpointer   gimp_atomic_slist_pop_head  (GSList   * volatile *list);
+
+
+#endif /* __GIMP_ATOMIC_H__ */
diff --git a/app/core/gimp-batch.c b/app/core/gimp-batch.c
new file mode 100644
index 0000000..e7908a2
--- /dev/null
+++ b/app/core/gimp-batch.c
@@ -0,0 +1,203 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+#include <stdlib.h>
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+
+#include "core-types.h"
+
+#include "gimp.h"
+#include "gimp-batch.h"
+#include "gimpparamspecs.h"
+
+#include "pdb/gimppdb.h"
+#include "pdb/gimpprocedure.h"
+
+#include "gimp-intl.h"
+
+
+#define BATCH_DEFAULT_EVAL_PROC   "plug-in-script-fu-eval"
+
+
+static void  gimp_batch_exit_after_callback (Gimp          *gimp) G_GNUC_NORETURN;
+
+static void  gimp_batch_run_cmd             (Gimp          *gimp,
+                                             const gchar   *proc_name,
+                                             GimpProcedure *procedure,
+                                             GimpRunMode    run_mode,
+                                             const gchar   *cmd);
+
+
+void
+gimp_batch_run (Gimp         *gimp,
+                const gchar  *batch_interpreter,
+                const gchar **batch_commands)
+{
+  gulong  exit_id;
+
+  if (! batch_commands || ! batch_commands[0])
+    return;
+
+  exit_id = g_signal_connect_after (gimp, "exit",
+                                    G_CALLBACK (gimp_batch_exit_after_callback),
+                                    NULL);
+
+  if (! batch_interpreter)
+    {
+      batch_interpreter = g_getenv ("GIMP_BATCH_INTERPRETER");
+
+      if (! batch_interpreter)
+        {
+          batch_interpreter = BATCH_DEFAULT_EVAL_PROC;
+
+          if (gimp->be_verbose)
+            g_printerr ("No batch interpreter specified, using the default "
+                        "'%s'.\n", batch_interpreter);
+        }
+    }
+
+  /*  script-fu text console, hardcoded for backward compatibility  */
+
+  if (strcmp (batch_interpreter, "plug-in-script-fu-eval") == 0 &&
+      strcmp (batch_commands[0], "-") == 0)
+    {
+      const gchar   *proc_name = "plug-in-script-fu-text-console";
+      GimpProcedure *procedure = gimp_pdb_lookup_procedure (gimp->pdb,
+                                                            proc_name);
+
+      if (procedure)
+        gimp_batch_run_cmd (gimp, proc_name, procedure,
+                            GIMP_RUN_NONINTERACTIVE, NULL);
+      else
+        g_message (_("The batch interpreter '%s' is not available. "
+                     "Batch mode disabled."), proc_name);
+    }
+  else
+    {
+      GimpProcedure *eval_proc = gimp_pdb_lookup_procedure (gimp->pdb,
+                                                            batch_interpreter);
+
+      if (eval_proc)
+        {
+          gint i;
+
+          for (i = 0; batch_commands[i]; i++)
+            gimp_batch_run_cmd (gimp, batch_interpreter, eval_proc,
+                                GIMP_RUN_NONINTERACTIVE, batch_commands[i]);
+        }
+      else
+        {
+          g_message (_("The batch interpreter '%s' is not available. "
+                       "Batch mode disabled."), batch_interpreter);
+        }
+    }
+
+  g_signal_handler_disconnect (gimp, exit_id);
+}
+
+
+/*
+ * The purpose of this handler is to exit GIMP cleanly when the batch
+ * procedure calls the gimp-exit procedure. Without this callback, the
+ * message "batch command experienced an execution error" would appear
+ * and gimp would hang forever.
+ */
+static void
+gimp_batch_exit_after_callback (Gimp *gimp)
+{
+  if (gimp->be_verbose)
+    g_print ("EXIT: %s\n", G_STRFUNC);
+
+  gegl_exit ();
+
+  exit (EXIT_SUCCESS);
+}
+
+static void
+gimp_batch_run_cmd (Gimp          *gimp,
+                    const gchar   *proc_name,
+                    GimpProcedure *procedure,
+                    GimpRunMode    run_mode,
+                    const gchar   *cmd)
+{
+  GimpValueArray *args;
+  GimpValueArray *return_vals;
+  GError         *error = NULL;
+  gint            i     = 0;
+
+  args = gimp_procedure_get_arguments (procedure);
+
+  if (procedure->num_args > i &&
+      GIMP_IS_PARAM_SPEC_INT32 (procedure->args[i]))
+    g_value_set_int (gimp_value_array_index (args, i++), run_mode);
+
+  if (procedure->num_args > i &&
+      GIMP_IS_PARAM_SPEC_STRING (procedure->args[i]))
+    g_value_set_static_string (gimp_value_array_index (args, i++), cmd);
+
+  return_vals =
+    gimp_pdb_execute_procedure_by_name_args (gimp->pdb,
+                                             gimp_get_user_context (gimp),
+                                             NULL, &error,
+                                             proc_name, args);
+
+  switch (g_value_get_enum (gimp_value_array_index (return_vals, 0)))
+    {
+    case GIMP_PDB_EXECUTION_ERROR:
+      if (error)
+        {
+          g_printerr ("batch command experienced an execution error:\n"
+                      "%s\n", error->message);
+        }
+      else
+        {
+          g_printerr ("batch command experienced an execution error\n");
+        }
+      break;
+
+    case GIMP_PDB_CALLING_ERROR:
+      if (error)
+        {
+          g_printerr ("batch command experienced a calling error:\n"
+                      "%s\n", error->message);
+        }
+      else
+        {
+          g_printerr ("batch command experienced a calling error\n");
+        }
+      break;
+
+    case GIMP_PDB_SUCCESS:
+      g_printerr ("batch command executed successfully\n");
+      break;
+    }
+
+  gimp_value_array_unref (return_vals);
+  gimp_value_array_unref (args);
+
+  if (error)
+    g_error_free (error);
+
+  return;
+}
diff --git a/app/core/gimp-batch.h b/app/core/gimp-batch.h
new file mode 100644
index 0000000..3e6945c
--- /dev/null
+++ b/app/core/gimp-batch.h
@@ -0,0 +1,27 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_BATCH_H__
+#define __GIMP_BATCH_H__
+
+
+void   gimp_batch_run (Gimp         *gimp,
+                       const gchar  *batch_interpreter,
+                       const gchar **batch_commands);
+
+
+#endif /* __GIMP_BATCH_H__ */
diff --git a/app/core/gimp-cairo.c b/app/core/gimp-cairo.c
new file mode 100644
index 0000000..9d5574f
--- /dev/null
+++ b/app/core/gimp-cairo.c
@@ -0,0 +1,217 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimp-cairo.c
+ * Copyright (C) 2010-2012  Michael Natterer <mitch@gimp.org>
+ *
+ * Some code here is based on code from librsvg that was originally
+ * written by Raph Levien <raph@artofcode.com> for Gill.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <cairo.h>
+#include <gegl.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "libgimpmath/gimpmath.h"
+#include "libgimpcolor/gimpcolor.h"
+
+#include "core-types.h"
+
+#include "gimp-cairo.h"
+
+
+#define REV (2.0 * G_PI)
+
+
+static cairo_user_data_key_t surface_data_key = { 0, };
+
+
+cairo_pattern_t *
+gimp_cairo_pattern_create_stipple (const GimpRGB *fg,
+                                   const GimpRGB *bg,
+                                   gint           index,
+                                   gdouble        offset_x,
+                                   gdouble        offset_y)
+{
+  cairo_surface_t *surface;
+  cairo_pattern_t *pattern;
+  guchar          *data;
+  guchar          *d;
+  guchar           fg_r, fg_g, fg_b, fg_a;
+  guchar           bg_r, bg_g, bg_b, bg_a;
+  gint             x, y;
+
+  g_return_val_if_fail (fg != NULL, NULL);
+  g_return_val_if_fail (bg != NULL, NULL);
+
+  data = g_malloc (8 * 8 * 4);
+
+  gimp_rgba_get_uchar (fg, &fg_r, &fg_g, &fg_b, &fg_a);
+  gimp_rgba_get_uchar (bg, &bg_r, &bg_g, &bg_b, &bg_a);
+
+  d = data;
+
+  for (y = 0; y < 8; y++)
+    {
+      for (x = 0; x < 8; x++)
+        {
+          if ((x + y + index) % 8 >= 4)
+            GIMP_CAIRO_ARGB32_SET_PIXEL (d, fg_r, fg_g, fg_b, fg_a);
+          else
+            GIMP_CAIRO_ARGB32_SET_PIXEL (d, bg_r, bg_g, bg_b, bg_a);
+
+          d += 4;
+        }
+    }
+
+  surface = cairo_image_surface_create_for_data (data,
+                                                 CAIRO_FORMAT_ARGB32,
+                                                 8, 8, 8 * 4);
+  cairo_surface_set_user_data (surface, &surface_data_key,
+                               data, (cairo_destroy_func_t) g_free);
+
+  pattern = cairo_pattern_create_for_surface (surface);
+  cairo_pattern_set_extend (pattern, CAIRO_EXTEND_REPEAT);
+
+  cairo_surface_destroy (surface);
+
+  if (offset_x != 0.0 || offset_y != 0.0)
+    {
+      cairo_matrix_t matrix;
+
+      cairo_matrix_init_translate (&matrix,
+                                   fmod (offset_x, 8),
+                                   fmod (offset_y, 8));
+      cairo_pattern_set_matrix (pattern, &matrix);
+    }
+
+  return pattern;
+}
+
+void
+gimp_cairo_arc (cairo_t *cr,
+                gdouble  center_x,
+                gdouble  center_y,
+                gdouble  radius,
+                gdouble  start_angle,
+                gdouble  slice_angle)
+{
+  g_return_if_fail (cr != NULL);
+
+  if (slice_angle >= 0)
+    {
+      cairo_arc_negative (cr, center_x, center_y, radius,
+                          - start_angle,
+                          - start_angle - slice_angle);
+    }
+  else
+    {
+      cairo_arc (cr, center_x, center_y, radius,
+                 - start_angle,
+                 - start_angle - slice_angle);
+    }
+}
+
+void
+gimp_cairo_rounded_rectangle (cairo_t *cr,
+                              gdouble  x,
+                              gdouble  y,
+                              gdouble  width,
+                              gdouble  height,
+                              gdouble  corner_radius)
+{
+  g_return_if_fail (cr != NULL);
+
+  if (width < 0.0)
+    {
+      x     += width;
+      width  = -width;
+    }
+
+  if (height < 0.0)
+    {
+      y      += height;
+      height  = -height;
+    }
+
+  corner_radius = CLAMP (corner_radius, 0.0, MIN (width, height) / 2.0);
+
+  if (corner_radius == 0.0)
+    {
+      cairo_rectangle (cr, x, y, width, height);
+
+      return;
+    }
+
+  cairo_new_sub_path (cr);
+
+  cairo_arc     (cr,
+                 x + corner_radius, y + corner_radius,
+                 corner_radius,
+                 0.50 * REV, 0.75 * REV);
+  cairo_line_to (cr,
+                 x + width - corner_radius, y);
+
+  cairo_arc     (cr,
+                 x + width - corner_radius, y + corner_radius,
+                 corner_radius,
+                 0.75 * REV, 1.00 * REV);
+  cairo_line_to (cr,
+                 x + width, y + height - corner_radius);
+
+  cairo_arc     (cr,
+                 x + width - corner_radius, y + height - corner_radius,
+                 corner_radius,
+                 0.00 * REV, 0.25 * REV);
+  cairo_line_to (cr,
+                 x + corner_radius, y + height);
+
+  cairo_arc     (cr,
+                 x + corner_radius, y + height - corner_radius,
+                 corner_radius,
+                 0.25 * REV, 0.50 * REV);
+  cairo_line_to (cr,
+                 x, y + corner_radius);
+
+  cairo_close_path (cr);
+}
+
+void
+gimp_cairo_segments (cairo_t     *cr,
+                     GimpSegment *segs,
+                     gint         n_segs)
+{
+  gint i;
+
+  g_return_if_fail (cr != NULL);
+  g_return_if_fail (segs != NULL && n_segs > 0);
+
+  for (i = 0; i < n_segs; i++)
+    {
+      if (segs[i].x1 == segs[i].x2)
+        {
+          cairo_move_to (cr, segs[i].x1 + 0.5, segs[i].y1 + 0.5);
+          cairo_line_to (cr, segs[i].x2 + 0.5, segs[i].y2 - 0.5);
+        }
+      else
+        {
+          cairo_move_to (cr, segs[i].x1 + 0.5, segs[i].y1 + 0.5);
+          cairo_line_to (cr, segs[i].x2 - 0.5, segs[i].y2 + 0.5);
+        }
+    }
+}
diff --git a/app/core/gimp-cairo.h b/app/core/gimp-cairo.h
new file mode 100644
index 0000000..b767740
--- /dev/null
+++ b/app/core/gimp-cairo.h
@@ -0,0 +1,51 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimp-cairo.h
+ * Copyright (C) 2010-2012  Michael Natterer <mitch@gimp.org>
+ *
+ * Some code here is based on code from librsvg that was originally
+ * written by Raph Levien <raph@artofcode.com> for Gill.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __APP_GIMP_CAIRO_H__
+#define __APP_GIMP_CAIRO_H__
+
+
+cairo_pattern_t * gimp_cairo_pattern_create_stipple (const GimpRGB   *fg,
+                                                     const GimpRGB   *bg,
+                                                     gint             index,
+                                                     gdouble          offset_x,
+                                                     gdouble          offset_y);
+
+void              gimp_cairo_arc                    (cairo_t         *cr,
+                                                     gdouble          center_x,
+                                                     gdouble          center_y,
+                                                     gdouble          radius,
+                                                     gdouble          start_angle,
+                                                     gdouble          slice_angle);
+void              gimp_cairo_rounded_rectangle      (cairo_t         *cr,
+                                                     gdouble          x,
+                                                     gdouble          y,
+                                                     gdouble          width,
+                                                     gdouble          height,
+                                                     gdouble          corner_radius);
+void              gimp_cairo_segments               (cairo_t         *cr,
+                                                     GimpSegment     *segs,
+                                                     gint             n_segs);
+
+
+#endif /* __APP_GIMP_CAIRO_H__ */
diff --git a/app/core/gimp-contexts.c b/app/core/gimp-contexts.c
new file mode 100644
index 0000000..59d1e53
--- /dev/null
+++ b/app/core/gimp-contexts.c
@@ -0,0 +1,161 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1999 Spencer Kimball and Peter Mattis
+ *
+ * gimp-contexts.c
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpconfig/gimpconfig.h"
+
+#include "core-types.h"
+
+#include "gimp.h"
+#include "gimperror.h"
+#include "gimp-contexts.h"
+#include "gimpcontext.h"
+
+#include "config/gimpconfig-file.h"
+
+#include "gimp-intl.h"
+
+
+void
+gimp_contexts_init (Gimp *gimp)
+{
+  GimpContext *context;
+
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+
+  /*  the default context contains the user's saved preferences
+   *
+   *  TODO: load from disk
+   */
+  context = gimp_context_new (gimp, "Default", NULL);
+  gimp_set_default_context (gimp, context);
+  g_object_unref (context);
+
+  /*  the initial user_context is a straight copy of the default context
+   */
+  context = gimp_context_new (gimp, "User", context);
+  gimp_set_user_context (gimp, context);
+  g_object_unref (context);
+}
+
+void
+gimp_contexts_exit (Gimp *gimp)
+{
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+
+  gimp_set_user_context (gimp, NULL);
+  gimp_set_default_context (gimp, NULL);
+}
+
+gboolean
+gimp_contexts_load (Gimp    *gimp,
+                    GError **error)
+{
+  GFile    *file;
+  GError   *my_error = NULL;
+  gboolean  success;
+
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  file = gimp_directory_file ("contextrc", NULL);
+
+  if (gimp->be_verbose)
+    g_print ("Parsing '%s'\n", gimp_file_get_utf8_name (file));
+
+  success = gimp_config_deserialize_gfile (GIMP_CONFIG (gimp_get_user_context (gimp)),
+                                           file,
+                                           NULL, &my_error);
+
+  g_object_unref (file);
+
+  if (! success)
+    {
+      if (my_error->code == GIMP_CONFIG_ERROR_OPEN_ENOENT)
+        {
+          g_clear_error (&my_error);
+          success = TRUE;
+        }
+      else
+        {
+          g_propagate_error (error, my_error);
+        }
+    }
+
+  return success;
+}
+
+gboolean
+gimp_contexts_save (Gimp    *gimp,
+                    GError **error)
+{
+  GFile    *file;
+  gboolean  success;
+
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  file = gimp_directory_file ("contextrc", NULL);
+
+  if (gimp->be_verbose)
+    g_print ("Writing '%s'\n", gimp_file_get_utf8_name (file));
+
+  success = gimp_config_serialize_to_gfile (GIMP_CONFIG (gimp_get_user_context (gimp)),
+                                            file,
+                                            "GIMP user context",
+                                            "end of user context",
+                                            NULL, error);
+
+  g_object_unref (file);
+
+  return success;
+}
+
+gboolean
+gimp_contexts_clear (Gimp    *gimp,
+                     GError **error)
+{
+  GFile    *file;
+  GError   *my_error = NULL;
+  gboolean  success  = TRUE;
+
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), FALSE);
+
+  file = gimp_directory_file ("contextrc", NULL);
+
+  if (! g_file_delete (file, NULL, &my_error) &&
+      my_error->code != G_IO_ERROR_NOT_FOUND)
+    {
+      success = FALSE;
+
+      g_set_error (error, GIMP_ERROR, GIMP_FAILED,
+                   _("Deleting \"%s\" failed: %s"),
+                   gimp_file_get_utf8_name (file), my_error->message);
+    }
+
+  g_clear_error (&my_error);
+  g_object_unref (file);
+
+  return success;
+}
diff --git a/app/core/gimp-contexts.h b/app/core/gimp-contexts.h
new file mode 100644
index 0000000..9aa402b
--- /dev/null
+++ b/app/core/gimp-contexts.h
@@ -0,0 +1,36 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimp-contexts.h
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_CONTEXTS_H__
+#define __GIMP_CONTEXTS_H__
+
+
+void       gimp_contexts_init  (Gimp    *gimp);
+void       gimp_contexts_exit  (Gimp    *gimp);
+
+gboolean   gimp_contexts_load  (Gimp    *gimp,
+                                GError **error);
+gboolean   gimp_contexts_save  (Gimp    *gimp,
+                                GError **error);
+
+gboolean   gimp_contexts_clear (Gimp    *gimp,
+                                GError **error);
+
+
+#endif  /*  __GIMP_CONTEXTS_H__  */
diff --git a/app/core/gimp-data-factories.c b/app/core/gimp-data-factories.c
new file mode 100644
index 0000000..69b5e2a
--- /dev/null
+++ b/app/core/gimp-data-factories.c
@@ -0,0 +1,433 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-2002 Spencer Kimball, Peter Mattis, and others
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpconfig/gimpconfig.h"
+
+#include "core-types.h"
+
+#include "config/gimprc.h"
+
+#include "gimp.h"
+#include "gimp-data-factories.h"
+#include "gimp-gradients.h"
+#include "gimp-memsize.h"
+#include "gimp-palettes.h"
+#include "gimpcontainer.h"
+#include "gimpbrush-load.h"
+#include "gimpbrush.h"
+#include "gimpbrushclipboard.h"
+#include "gimpbrushgenerated-load.h"
+#include "gimpbrushpipe-load.h"
+#include "gimpdataloaderfactory.h"
+#include "gimpdynamics.h"
+#include "gimpdynamics-load.h"
+#include "gimpgradient-load.h"
+#include "gimpgradient.h"
+#include "gimpmybrush-load.h"
+#include "gimpmybrush.h"
+#include "gimppalette-load.h"
+#include "gimppalette.h"
+#include "gimppattern-load.h"
+#include "gimppattern.h"
+#include "gimppatternclipboard.h"
+#include "gimptagcache.h"
+#include "gimptoolpreset.h"
+#include "gimptoolpreset-load.h"
+
+#include "text/gimpfontfactory.h"
+
+#include "gimp-intl.h"
+
+
+void
+gimp_data_factories_init (Gimp *gimp)
+{
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+
+  gimp->brush_factory =
+    gimp_data_loader_factory_new (gimp,
+                                  GIMP_TYPE_BRUSH,
+                                  "brush-path",
+                                  "brush-path-writable",
+                                  gimp_brush_new,
+                                  gimp_brush_get_standard);
+  gimp_object_set_static_name (GIMP_OBJECT (gimp->brush_factory),
+                               "brush factory");
+  gimp_data_loader_factory_add_loader (gimp->brush_factory,
+                                       "GIMP Brush",
+                                       gimp_brush_load,
+                                       GIMP_BRUSH_FILE_EXTENSION,
+                                       TRUE);
+  gimp_data_loader_factory_add_loader (gimp->brush_factory,
+                                       "GIMP Brush Pixmap",
+                                       gimp_brush_load,
+                                       GIMP_BRUSH_PIXMAP_FILE_EXTENSION,
+                                       FALSE);
+  gimp_data_loader_factory_add_loader (gimp->brush_factory,
+                                       "Photoshop ABR Brush",
+                                       gimp_brush_load_abr,
+                                       GIMP_BRUSH_PS_FILE_EXTENSION,
+                                       FALSE);
+  gimp_data_loader_factory_add_loader (gimp->brush_factory,
+                                       "Paint Shop Pro JBR Brush",
+                                       gimp_brush_load_abr,
+                                       GIMP_BRUSH_PSP_FILE_EXTENSION,
+                                       FALSE);
+ gimp_data_loader_factory_add_loader (gimp->brush_factory,
+                                       "GIMP Generated Brush",
+                                       gimp_brush_generated_load,
+                                       GIMP_BRUSH_GENERATED_FILE_EXTENSION,
+                                       TRUE);
+  gimp_data_loader_factory_add_loader (gimp->brush_factory,
+                                       "GIMP Brush Pipe",
+                                       gimp_brush_pipe_load,
+                                       GIMP_BRUSH_PIPE_FILE_EXTENSION,
+                                       TRUE);
+
+  gimp->dynamics_factory =
+    gimp_data_loader_factory_new (gimp,
+                                  GIMP_TYPE_DYNAMICS,
+                                  "dynamics-path",
+                                  "dynamics-path-writable",
+                                  gimp_dynamics_new,
+                                  gimp_dynamics_get_standard);
+  gimp_object_set_static_name (GIMP_OBJECT (gimp->dynamics_factory),
+                               "dynamics factory");
+  gimp_data_loader_factory_add_loader (gimp->dynamics_factory,
+                                       "GIMP Paint Dynamics",
+                                       gimp_dynamics_load,
+                                       GIMP_DYNAMICS_FILE_EXTENSION,
+                                       TRUE);
+
+  gimp->mybrush_factory =
+    gimp_data_loader_factory_new (gimp,
+                                  GIMP_TYPE_MYBRUSH,
+                                  "mypaint-brush-path",
+                                  "mypaint-brush-path-writable",
+                                  NULL,
+                                  NULL);
+  gimp_object_set_static_name (GIMP_OBJECT (gimp->mybrush_factory),
+                               "mypaint brush factory");
+  gimp_data_loader_factory_add_loader (gimp->mybrush_factory,
+                                       "MyPaint Brush",
+                                       gimp_mybrush_load,
+                                       GIMP_MYBRUSH_FILE_EXTENSION,
+                                       FALSE);
+
+  gimp->pattern_factory =
+    gimp_data_loader_factory_new (gimp,
+                                  GIMP_TYPE_PATTERN,
+                                  "pattern-path",
+                                  "pattern-path-writable",
+                                  NULL,
+                                  gimp_pattern_get_standard);
+  gimp_object_set_static_name (GIMP_OBJECT (gimp->pattern_factory),
+                               "pattern factory");
+  gimp_data_loader_factory_add_loader (gimp->pattern_factory,
+                                       "GIMP Pattern",
+                                       gimp_pattern_load,
+                                       GIMP_PATTERN_FILE_EXTENSION,
+                                       TRUE);
+  gimp_data_loader_factory_add_fallback (gimp->pattern_factory,
+                                         "Pattern from GdkPixbuf",
+                                         gimp_pattern_load_pixbuf);
+
+  gimp->gradient_factory =
+    gimp_data_loader_factory_new (gimp,
+                                  GIMP_TYPE_GRADIENT,
+                                  "gradient-path",
+                                  "gradient-path-writable",
+                                  gimp_gradient_new,
+                                  gimp_gradient_get_standard);
+  gimp_object_set_static_name (GIMP_OBJECT (gimp->gradient_factory),
+                               "gradient factory");
+  gimp_data_loader_factory_add_loader (gimp->gradient_factory,
+                                       "GIMP Gradient",
+                                       gimp_gradient_load,
+                                       GIMP_GRADIENT_FILE_EXTENSION,
+                                       TRUE);
+  gimp_data_loader_factory_add_loader (gimp->gradient_factory,
+                                       "SVG Gradient",
+                                       gimp_gradient_load_svg,
+                                       GIMP_GRADIENT_SVG_FILE_EXTENSION,
+                                       FALSE);
+
+  gimp->palette_factory =
+    gimp_data_loader_factory_new (gimp,
+                                  GIMP_TYPE_PALETTE,
+                                  "palette-path",
+                                  "palette-path-writable",
+                                  gimp_palette_new,
+                                  gimp_palette_get_standard);
+  gimp_object_set_static_name (GIMP_OBJECT (gimp->palette_factory),
+                               "palette factory");
+  gimp_data_loader_factory_add_loader (gimp->palette_factory,
+                                       "GIMP Palette",
+                                       gimp_palette_load,
+                                       GIMP_PALETTE_FILE_EXTENSION,
+                                       TRUE);
+
+  gimp->font_factory =
+    gimp_font_factory_new (gimp,
+                           "font-path");
+  gimp_object_set_static_name (GIMP_OBJECT (gimp->font_factory),
+                               "font factory");
+
+  gimp->tool_preset_factory =
+    gimp_data_loader_factory_new (gimp,
+                                  GIMP_TYPE_TOOL_PRESET,
+                                  "tool-preset-path",
+                                  "tool-preset-path-writable",
+                                  gimp_tool_preset_new,
+                                  NULL);
+  gimp_object_set_static_name (GIMP_OBJECT (gimp->tool_preset_factory),
+                               "tool preset factory");
+  gimp_data_loader_factory_add_loader (gimp->tool_preset_factory,
+                                       "GIMP Tool Preset",
+                                       gimp_tool_preset_load,
+                                       GIMP_TOOL_PRESET_FILE_EXTENSION,
+                                       TRUE);
+
+  gimp->tag_cache = gimp_tag_cache_new ();
+}
+
+void
+gimp_data_factories_add_builtin (Gimp *gimp)
+{
+  GimpData *data;
+
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+
+  /*  add the builtin FG -> BG etc. gradients  */
+  gimp_gradients_init (gimp);
+
+  /*  add the color history palette  */
+  gimp_palettes_init (gimp);
+
+  /*  add the clipboard brushes  */
+  data = gimp_brush_clipboard_new (gimp, FALSE);
+  gimp_data_make_internal (data, "gimp-brush-clipboard-image");
+  gimp_container_add (gimp_data_factory_get_container (gimp->brush_factory),
+                      GIMP_OBJECT (data));
+  g_object_unref (data);
+
+  data = gimp_brush_clipboard_new (gimp, TRUE);
+  gimp_data_make_internal (data, "gimp-brush-clipboard-mask");
+  gimp_container_add (gimp_data_factory_get_container (gimp->brush_factory),
+                      GIMP_OBJECT (data));
+  g_object_unref (data);
+
+  /*  add the clipboard pattern  */
+  data = gimp_pattern_clipboard_new (gimp);
+  gimp_data_make_internal (data, "gimp-pattern-clipboard-image");
+  gimp_container_add (gimp_data_factory_get_container (gimp->pattern_factory),
+                      GIMP_OBJECT (data));
+  g_object_unref (data);
+}
+
+void
+gimp_data_factories_clear (Gimp *gimp)
+{
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+
+  if (gimp->brush_factory)
+    gimp_data_factory_data_free (gimp->brush_factory);
+
+  if (gimp->dynamics_factory)
+    gimp_data_factory_data_free (gimp->dynamics_factory);
+
+  if (gimp->mybrush_factory)
+    gimp_data_factory_data_free (gimp->mybrush_factory);
+
+  if (gimp->pattern_factory)
+    gimp_data_factory_data_free (gimp->pattern_factory);
+
+  if (gimp->gradient_factory)
+    gimp_data_factory_data_free (gimp->gradient_factory);
+
+  if (gimp->palette_factory)
+    gimp_data_factory_data_free (gimp->palette_factory);
+
+  if (gimp->font_factory)
+    gimp_data_factory_data_free (gimp->font_factory);
+
+  if (gimp->tool_preset_factory)
+    gimp_data_factory_data_free (gimp->tool_preset_factory);
+}
+
+void
+gimp_data_factories_exit (Gimp *gimp)
+{
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+
+  g_clear_object (&gimp->brush_factory);
+  g_clear_object (&gimp->dynamics_factory);
+  g_clear_object (&gimp->mybrush_factory);
+  g_clear_object (&gimp->pattern_factory);
+  g_clear_object (&gimp->gradient_factory);
+  g_clear_object (&gimp->palette_factory);
+  g_clear_object (&gimp->font_factory);
+  g_clear_object (&gimp->tool_preset_factory);
+  g_clear_object (&gimp->tag_cache);
+}
+
+gint64
+gimp_data_factories_get_memsize (Gimp   *gimp,
+                                 gint64 *gui_size)
+{
+  gint64 memsize = 0;
+
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), 0);
+
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (gimp->named_buffers),
+                                      gui_size);
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (gimp->brush_factory),
+                                      gui_size);
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (gimp->dynamics_factory),
+                                      gui_size);
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (gimp->mybrush_factory),
+                                      gui_size);
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (gimp->pattern_factory),
+                                      gui_size);
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (gimp->gradient_factory),
+                                      gui_size);
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (gimp->palette_factory),
+                                      gui_size);
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (gimp->font_factory),
+                                      gui_size);
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (gimp->tool_preset_factory),
+                                      gui_size);
+
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (gimp->tag_cache),
+                                      gui_size);
+
+  return memsize;
+}
+
+void
+gimp_data_factories_data_clean (Gimp *gimp)
+{
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+
+  gimp_data_factory_data_clean (gimp->brush_factory);
+  gimp_data_factory_data_clean (gimp->dynamics_factory);
+  gimp_data_factory_data_clean (gimp->mybrush_factory);
+  gimp_data_factory_data_clean (gimp->pattern_factory);
+  gimp_data_factory_data_clean (gimp->gradient_factory);
+  gimp_data_factory_data_clean (gimp->palette_factory);
+  gimp_data_factory_data_clean (gimp->font_factory);
+  gimp_data_factory_data_clean (gimp->tool_preset_factory);
+}
+
+void
+gimp_data_factories_load (Gimp               *gimp,
+                          GimpInitStatusFunc  status_callback)
+{
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+
+  /*  initialize the list of gimp brushes    */
+  status_callback (NULL, _("Brushes"), 0.1);
+  gimp_data_factory_data_init (gimp->brush_factory, gimp->user_context,
+                               gimp->no_data);
+
+  /*  initialize the list of gimp dynamics   */
+  status_callback (NULL, _("Dynamics"), 0.15);
+  gimp_data_factory_data_init (gimp->dynamics_factory, gimp->user_context,
+                               gimp->no_data);
+
+  /*  initialize the list of mypaint brushes    */
+  status_callback (NULL, _("MyPaint Brushes"), 0.2);
+  gimp_data_factory_data_init (gimp->mybrush_factory, gimp->user_context,
+                               gimp->no_data);
+
+  /*  initialize the list of gimp patterns   */
+  status_callback (NULL, _("Patterns"), 0.3);
+  gimp_data_factory_data_init (gimp->pattern_factory, gimp->user_context,
+                               gimp->no_data);
+
+  /*  initialize the list of gimp palettes   */
+  status_callback (NULL, _("Palettes"), 0.4);
+  gimp_data_factory_data_init (gimp->palette_factory, gimp->user_context,
+                               gimp->no_data);
+
+  /*  initialize the list of gimp gradients  */
+  status_callback (NULL, _("Gradients"), 0.5);
+  gimp_data_factory_data_init (gimp->gradient_factory, gimp->user_context,
+                               gimp->no_data);
+
+  /*  initialize the color history   */
+  status_callback (NULL, _("Color History"), 0.55);
+  gimp_palettes_load (gimp);
+
+  /*  initialize the list of gimp fonts   */
+  status_callback (NULL, _("Fonts"), 0.6);
+  gimp_data_factory_data_init (gimp->font_factory, gimp->user_context,
+                               gimp->no_fonts);
+
+  /*  initialize the list of gimp tool presets if we have a GUI  */
+  if (! gimp->no_interface)
+    {
+      status_callback (NULL, _("Tool Presets"), 0.7);
+      gimp_data_factory_data_init (gimp->tool_preset_factory, gimp->user_context,
+                                   gimp->no_data);
+    }
+
+  /* update tag cache */
+  status_callback (NULL, _("Updating tag cache"), 0.75);
+  gimp_tag_cache_load (gimp->tag_cache);
+  gimp_tag_cache_add_container (gimp->tag_cache,
+                                gimp_data_factory_get_container (gimp->brush_factory));
+  gimp_tag_cache_add_container (gimp->tag_cache,
+                                gimp_data_factory_get_container (gimp->dynamics_factory));
+  gimp_tag_cache_add_container (gimp->tag_cache,
+                                gimp_data_factory_get_container (gimp->mybrush_factory));
+  gimp_tag_cache_add_container (gimp->tag_cache,
+                                gimp_data_factory_get_container (gimp->pattern_factory));
+  gimp_tag_cache_add_container (gimp->tag_cache,
+                                gimp_data_factory_get_container (gimp->gradient_factory));
+  gimp_tag_cache_add_container (gimp->tag_cache,
+                                gimp_data_factory_get_container (gimp->palette_factory));
+  gimp_tag_cache_add_container (gimp->tag_cache,
+                                gimp_data_factory_get_container (gimp->font_factory));
+  gimp_tag_cache_add_container (gimp->tag_cache,
+                                gimp_data_factory_get_container (gimp->tool_preset_factory));
+}
+
+void
+gimp_data_factories_save (Gimp *gimp)
+{
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+
+  gimp_tag_cache_save (gimp->tag_cache);
+
+  gimp_data_factory_data_save (gimp->brush_factory);
+  gimp_data_factory_data_save (gimp->dynamics_factory);
+  gimp_data_factory_data_save (gimp->mybrush_factory);
+  gimp_data_factory_data_save (gimp->pattern_factory);
+  gimp_data_factory_data_save (gimp->gradient_factory);
+  gimp_data_factory_data_save (gimp->palette_factory);
+  gimp_data_factory_data_save (gimp->font_factory);
+  gimp_data_factory_data_save (gimp->tool_preset_factory);
+
+  gimp_palettes_save (gimp);
+}
diff --git a/app/core/gimp-data-factories.h b/app/core/gimp-data-factories.h
new file mode 100644
index 0000000..d5b273d
--- /dev/null
+++ b/app/core/gimp-data-factories.h
@@ -0,0 +1,36 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-2002 Spencer Kimball, Peter Mattis, and others
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_DATA_FACTORIES_H__
+#define __GIMP_DATA_FACTORIES_H__
+
+
+void      gimp_data_factories_init        (Gimp               *gimp);
+void      gimp_data_factories_add_builtin (Gimp               *gimp);
+void      gimp_data_factories_clear       (Gimp               *gimp);
+void      gimp_data_factories_exit        (Gimp               *gimp);
+
+gint64    gimp_data_factories_get_memsize (Gimp   *gimp,
+                                           gint64 *gui_size);
+void      gimp_data_factories_data_clean  (Gimp   *gimp);
+
+void      gimp_data_factories_load        (Gimp               *gimp,
+                                           GimpInitStatusFunc  status_callback);
+void      gimp_data_factories_save        (Gimp               *gimp);
+
+
+#endif /* __GIMP_DATA_FACTORIES_H__ */
diff --git a/app/core/gimp-edit.c b/app/core/gimp-edit.c
new file mode 100644
index 0000000..372ad2d
--- /dev/null
+++ b/app/core/gimp-edit.c
@@ -0,0 +1,771 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <cairo.h>
+#include <gegl.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpcolor/gimpcolor.h"
+
+#include "core-types.h"
+
+#include "gimp.h"
+#include "gimp-edit.h"
+#include "gimpbuffer.h"
+#include "gimpcontext.h"
+#include "gimpgrouplayer.h"
+#include "gimpimage.h"
+#include "gimpimage-duplicate.h"
+#include "gimpimage-new.h"
+#include "gimpimage-undo.h"
+#include "gimplayer-floating-selection.h"
+#include "gimplayer-new.h"
+#include "gimplist.h"
+#include "gimppickable.h"
+#include "gimpselection.h"
+
+#include "gimp-intl.h"
+
+
+/*  local function protypes  */
+
+static GimpBuffer * gimp_edit_extract (GimpImage     *image,
+                                       GimpPickable  *pickable,
+                                       GimpContext   *context,
+                                       gboolean       cut_pixels,
+                                       GError       **error);
+
+
+/*  public functions  */
+
+GimpObject *
+gimp_edit_cut (GimpImage     *image,
+               GimpDrawable  *drawable,
+               GimpContext   *context,
+               GError       **error)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (drawable)), NULL);
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, NULL);
+
+  if (GIMP_IS_LAYER (drawable) &&
+      gimp_channel_is_empty (gimp_image_get_mask (image)))
+    {
+      GimpImage *clip_image;
+      gint       off_x, off_y;
+
+      gimp_item_get_offset (GIMP_ITEM (drawable), &off_x, &off_y);
+
+      clip_image = gimp_image_new_from_drawable (image->gimp, drawable);
+      g_object_set_data (G_OBJECT (clip_image), "offset-x",
+                         GINT_TO_POINTER (off_x));
+      g_object_set_data (G_OBJECT (clip_image), "offset-y",
+                         GINT_TO_POINTER (off_y));
+      gimp_container_remove (image->gimp->images, GIMP_OBJECT (clip_image));
+      gimp_set_clipboard_image (image->gimp, clip_image);
+      g_object_unref (clip_image);
+
+      gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_EDIT_CUT,
+                                   C_("undo-type", "Cut Layer"));
+
+      gimp_image_remove_layer (image, GIMP_LAYER (drawable),
+                               TRUE, NULL);
+
+      gimp_image_undo_group_end (image);
+
+      return GIMP_OBJECT (gimp_get_clipboard_image (image->gimp));
+    }
+  else
+    {
+      GimpBuffer *buffer;
+
+      buffer = gimp_edit_extract (image, GIMP_PICKABLE (drawable),
+                                  context, TRUE, error);
+
+      if (buffer)
+        {
+          gimp_set_clipboard_buffer (image->gimp, buffer);
+          g_object_unref (buffer);
+
+          return GIMP_OBJECT (gimp_get_clipboard_buffer (image->gimp));
+        }
+    }
+
+  return NULL;
+}
+
+GimpObject *
+gimp_edit_copy (GimpImage     *image,
+                GimpDrawable  *drawable,
+                GimpContext   *context,
+                GError       **error)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (drawable)), NULL);
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, NULL);
+
+  if (GIMP_IS_LAYER (drawable) &&
+      gimp_channel_is_empty (gimp_image_get_mask (image)))
+    {
+      GimpImage *clip_image;
+      gint       off_x, off_y;
+
+      gimp_item_get_offset (GIMP_ITEM (drawable), &off_x, &off_y);
+
+      clip_image = gimp_image_new_from_drawable (image->gimp, drawable);
+      g_object_set_data (G_OBJECT (clip_image), "offset-x",
+                         GINT_TO_POINTER (off_x));
+      g_object_set_data (G_OBJECT (clip_image), "offset-y",
+                         GINT_TO_POINTER (off_y));
+      gimp_container_remove (image->gimp->images, GIMP_OBJECT (clip_image));
+      gimp_set_clipboard_image (image->gimp, clip_image);
+      g_object_unref (clip_image);
+
+      return GIMP_OBJECT (gimp_get_clipboard_image (image->gimp));
+    }
+  else
+    {
+      GimpBuffer *buffer;
+
+      buffer = gimp_edit_extract (image, GIMP_PICKABLE (drawable),
+                                  context, FALSE, error);
+
+      if (buffer)
+        {
+          gimp_set_clipboard_buffer (image->gimp, buffer);
+          g_object_unref (buffer);
+
+          return GIMP_OBJECT (gimp_get_clipboard_buffer (image->gimp));
+        }
+    }
+
+  return NULL;
+}
+
+GimpBuffer *
+gimp_edit_copy_visible (GimpImage    *image,
+                        GimpContext  *context,
+                        GError      **error)
+{
+  GimpBuffer *buffer;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, NULL);
+
+  buffer = gimp_edit_extract (image, GIMP_PICKABLE (image),
+                              context, FALSE, error);
+
+  if (buffer)
+    {
+      gimp_set_clipboard_buffer (image->gimp, buffer);
+      g_object_unref (buffer);
+
+      return gimp_get_clipboard_buffer (image->gimp);
+    }
+
+  return NULL;
+}
+
+static gboolean
+gimp_edit_paste_is_in_place (GimpPasteType paste_type)
+{
+  switch (paste_type)
+    {
+    case GIMP_PASTE_TYPE_FLOATING:
+    case GIMP_PASTE_TYPE_FLOATING_INTO:
+    case GIMP_PASTE_TYPE_NEW_LAYER:
+      return FALSE;
+
+    case GIMP_PASTE_TYPE_FLOATING_IN_PLACE:
+    case GIMP_PASTE_TYPE_FLOATING_INTO_IN_PLACE:
+    case GIMP_PASTE_TYPE_NEW_LAYER_IN_PLACE:
+      return TRUE;
+    }
+
+  g_return_val_if_reached (FALSE);
+}
+
+static gboolean
+gimp_edit_paste_is_floating (GimpPasteType paste_type)
+{
+  switch (paste_type)
+    {
+    case GIMP_PASTE_TYPE_FLOATING:
+    case GIMP_PASTE_TYPE_FLOATING_INTO:
+    case GIMP_PASTE_TYPE_FLOATING_IN_PLACE:
+    case GIMP_PASTE_TYPE_FLOATING_INTO_IN_PLACE:
+      return TRUE;
+
+    case GIMP_PASTE_TYPE_NEW_LAYER:
+    case GIMP_PASTE_TYPE_NEW_LAYER_IN_PLACE:
+      return FALSE;
+    }
+
+  g_return_val_if_reached (FALSE);
+}
+
+static GimpLayer *
+gimp_edit_paste_get_layer (GimpImage     *image,
+                           GimpDrawable  *drawable,
+                           GimpObject    *paste,
+                           GimpPasteType *paste_type)
+{
+  GimpLayer  *layer = NULL;
+  const Babl *floating_format;
+
+  /*  change paste type to NEW_LAYER for cases where we can't attach a
+   *  floating selection
+   */
+  if (! drawable                                            ||
+      gimp_viewable_get_children (GIMP_VIEWABLE (drawable)) ||
+      gimp_item_is_content_locked (GIMP_ITEM (drawable)))
+    {
+      if (gimp_edit_paste_is_in_place (*paste_type))
+        *paste_type = GIMP_PASTE_TYPE_NEW_LAYER_IN_PLACE;
+      else
+        *paste_type = GIMP_PASTE_TYPE_NEW_LAYER;
+    }
+
+  /*  floating pastes always have the pasted-to drawable's format with
+   *  alpha; if drawable == NULL, user is pasting into an empty image
+   */
+  if (drawable && gimp_edit_paste_is_floating (*paste_type))
+    floating_format = gimp_drawable_get_format_with_alpha (drawable);
+  else
+    floating_format = gimp_image_get_layer_format (image, TRUE);
+
+  if (GIMP_IS_IMAGE (paste))
+    {
+      GType layer_type;
+
+      layer = gimp_image_get_layer_iter (GIMP_IMAGE (paste))->data;
+
+      switch (*paste_type)
+        {
+        case GIMP_PASTE_TYPE_FLOATING:
+        case GIMP_PASTE_TYPE_FLOATING_IN_PLACE:
+        case GIMP_PASTE_TYPE_FLOATING_INTO:
+        case GIMP_PASTE_TYPE_FLOATING_INTO_IN_PLACE:
+          /*  when pasting as floating make sure gimp_item_convert()
+           *  will turn group layers into normal layers, otherwise use
+           *  the same layer type so e.g. text information gets
+           *  preserved. See issue #2667.
+           */
+          if (GIMP_IS_GROUP_LAYER (layer))
+            layer_type = GIMP_TYPE_LAYER;
+          else
+            layer_type = G_TYPE_FROM_INSTANCE (layer);
+          break;
+
+        case GIMP_PASTE_TYPE_NEW_LAYER:
+        case GIMP_PASTE_TYPE_NEW_LAYER_IN_PLACE:
+          layer_type = G_TYPE_FROM_INSTANCE (layer);
+          break;
+
+        default:
+          g_return_val_if_reached (NULL);
+        }
+
+      layer = GIMP_LAYER (gimp_item_convert (GIMP_ITEM (layer),
+                                             image, layer_type));
+
+      switch (*paste_type)
+        {
+        case GIMP_PASTE_TYPE_FLOATING:
+        case GIMP_PASTE_TYPE_FLOATING_IN_PLACE:
+        case GIMP_PASTE_TYPE_FLOATING_INTO:
+        case GIMP_PASTE_TYPE_FLOATING_INTO_IN_PLACE:
+          /*  when pasting as floating selection, get rid of the layer mask,
+           *  and make sure the layer has the right format
+           */
+          if (gimp_layer_get_mask (layer))
+            gimp_layer_apply_mask (layer, GIMP_MASK_DISCARD, FALSE);
+
+          if (gimp_drawable_get_format (GIMP_DRAWABLE (layer)) !=
+              floating_format)
+            {
+              gimp_drawable_convert_type (GIMP_DRAWABLE (layer), image,
+                                          gimp_drawable_get_base_type (drawable),
+                                          gimp_drawable_get_precision (drawable),
+                                          TRUE,
+                                          NULL,
+                                          GEGL_DITHER_NONE, GEGL_DITHER_NONE,
+                                          FALSE, NULL);
+            }
+          break;
+
+        default:
+          break;
+        }
+    }
+  else if (GIMP_IS_BUFFER (paste))
+    {
+      layer = gimp_layer_new_from_buffer (GIMP_BUFFER (paste), image,
+                                          floating_format,
+                                          _("Pasted Layer"),
+                                          GIMP_OPACITY_OPAQUE,
+                                          gimp_image_get_default_new_layer_mode (image));
+    }
+
+  return layer;
+}
+
+static void
+gimp_edit_paste_get_viewport_offset (GimpImage    *image,
+                                     GimpDrawable *drawable,
+                                     GimpObject   *paste,
+                                     gint          viewport_x,
+                                     gint          viewport_y,
+                                     gint          viewport_width,
+                                     gint          viewport_height,
+                                     gint         *offset_x,
+                                     gint         *offset_y)
+{
+  gint     image_width;
+  gint     image_height;
+  gint     width;
+  gint     height;
+  gboolean clamp_to_image = TRUE;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (drawable == NULL || GIMP_IS_DRAWABLE (drawable));
+  g_return_if_fail (drawable == NULL ||
+                    gimp_item_is_attached (GIMP_ITEM (drawable)));
+  g_return_if_fail (GIMP_IS_VIEWABLE (paste));
+  g_return_if_fail (offset_x != NULL);
+  g_return_if_fail (offset_y != NULL);
+
+  image_width  = gimp_image_get_width  (image);
+  image_height = gimp_image_get_height (image);
+
+  gimp_viewable_get_size (GIMP_VIEWABLE (paste), &width, &height);
+
+  if (viewport_width  == image_width &&
+      viewport_height == image_height)
+    {
+      /* if the whole image is visible, act as if there was no viewport */
+
+      viewport_x      = 0;
+      viewport_y      = 0;
+      viewport_width  = 0;
+      viewport_height = 0;
+    }
+
+  if (drawable)
+    {
+      /*  if pasting to a drawable  */
+
+      GimpContainer *children;
+      gint           off_x, off_y;
+      gint           target_x, target_y;
+      gint           target_width, target_height;
+      gint           paste_x, paste_y;
+      gint           paste_width, paste_height;
+      gboolean       have_mask;
+
+      have_mask = ! gimp_channel_is_empty (gimp_image_get_mask (image));
+
+      gimp_item_get_offset (GIMP_ITEM (drawable), &off_x, &off_y);
+
+      children = gimp_viewable_get_children (GIMP_VIEWABLE (drawable));
+
+      if (children && gimp_container_get_n_children (children) == 0)
+        {
+          /* treat empty layer groups as image-sized, use the selection
+           * as target
+           */
+          gimp_item_bounds (GIMP_ITEM (gimp_image_get_mask (image)),
+                            &target_x, &target_y,
+                            &target_width, &target_height);
+        }
+      else
+        {
+          gimp_item_mask_intersect (GIMP_ITEM (drawable),
+                                    &target_x, &target_y,
+                                    &target_width, &target_height);
+        }
+
+      if (! have_mask         &&    /* if we have no mask */
+          viewport_width  > 0 &&    /* and we have a viewport */
+          viewport_height > 0 &&
+          (width  < target_width || /* and the paste is smaller than the target */
+           height < target_height) &&
+
+          /* and the viewport intersects with the target */
+          gimp_rectangle_intersect (viewport_x, viewport_y,
+                                    viewport_width, viewport_height,
+                                    off_x, off_y, /* target_x,y are 0 */
+                                    target_width, target_height,
+                                    &paste_x, &paste_y,
+                                    &paste_width, &paste_height))
+        {
+          /*  center on the viewport  */
+
+          *offset_x = paste_x + (paste_width - width)  / 2;
+          *offset_y = paste_y + (paste_height- height) / 2;
+        }
+      else
+        {
+          /*  otherwise center on the target  */
+
+          *offset_x = off_x + target_x + (target_width  - width)  / 2;
+          *offset_y = off_y + target_y + (target_height - height) / 2;
+
+          /*  and keep it that way  */
+          clamp_to_image = FALSE;
+        }
+    }
+  else if (viewport_width  > 0 &&  /* if we have a viewport */
+           viewport_height > 0 &&
+           (width  < image_width || /* and the paste is       */
+            height < image_height)) /* smaller than the image */
+    {
+      /*  center on the viewport  */
+
+      *offset_x = viewport_x + (viewport_width  - width)  / 2;
+      *offset_y = viewport_y + (viewport_height - height) / 2;
+    }
+  else
+    {
+      /*  otherwise center on the image  */
+
+      *offset_x = (image_width  - width)  / 2;
+      *offset_y = (image_height - height) / 2;
+
+      /*  and keep it that way  */
+      clamp_to_image = FALSE;
+    }
+
+  if (clamp_to_image)
+    {
+      /*  Ensure that the pasted layer is always within the image, if it
+       *  fits and aligned at top left if it doesn't. (See bug #142944).
+       */
+      *offset_x = MIN (*offset_x, image_width  - width);
+      *offset_y = MIN (*offset_y, image_height - height);
+      *offset_x = MAX (*offset_x, 0);
+      *offset_y = MAX (*offset_y, 0);
+    }
+}
+
+static void
+gimp_edit_paste_get_paste_offset (GimpImage    *image,
+                                  GimpDrawable *drawable,
+                                  GimpObject   *paste,
+                                  gint         *offset_x,
+                                  gint         *offset_y)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (drawable == NULL || GIMP_IS_DRAWABLE (drawable));
+  g_return_if_fail (drawable == NULL ||
+                    gimp_item_is_attached (GIMP_ITEM (drawable)));
+  g_return_if_fail (GIMP_IS_VIEWABLE (paste));
+  g_return_if_fail (offset_x != NULL);
+  g_return_if_fail (offset_y != NULL);
+
+  if (GIMP_IS_IMAGE (paste))
+    {
+      *offset_x = GPOINTER_TO_INT (g_object_get_data (G_OBJECT (paste),
+                                                      "offset-x"));
+      *offset_y = GPOINTER_TO_INT (g_object_get_data (G_OBJECT (paste),
+                                                      "offset-y"));
+    }
+  else if (GIMP_IS_BUFFER (paste))
+    {
+      GimpBuffer *buffer = GIMP_BUFFER (paste);
+
+      *offset_x = buffer->offset_x;
+      *offset_y = buffer->offset_y;
+    }
+}
+
+static GimpLayer *
+gimp_edit_paste_paste (GimpImage     *image,
+                       GimpDrawable  *drawable,
+                       GimpLayer     *layer,
+                       GimpPasteType  paste_type,
+                       gint           offset_x,
+                       gint           offset_y)
+{
+  gimp_item_translate (GIMP_ITEM (layer), offset_x, offset_y, FALSE);
+
+  gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_EDIT_PASTE,
+                               C_("undo-type", "Paste"));
+
+  switch (paste_type)
+    {
+    case GIMP_PASTE_TYPE_FLOATING:
+    case GIMP_PASTE_TYPE_FLOATING_IN_PLACE:
+      /*  if there is a selection mask clear it - this might not
+       *  always be desired, but in general, it seems like the correct
+       *  behavior
+       */
+      if (! gimp_channel_is_empty (gimp_image_get_mask (image)))
+        gimp_channel_clear (gimp_image_get_mask (image), NULL, TRUE);
+
+      /* fall thru */
+
+    case GIMP_PASTE_TYPE_FLOATING_INTO:
+    case GIMP_PASTE_TYPE_FLOATING_INTO_IN_PLACE:
+      floating_sel_attach (layer, drawable);
+      break;
+
+    case GIMP_PASTE_TYPE_NEW_LAYER:
+    case GIMP_PASTE_TYPE_NEW_LAYER_IN_PLACE:
+      {
+        GimpLayer *parent   = NULL;
+        gint       position = 0;
+
+        /*  always add on top of a passed layer, where we would attach
+         *  a floating selection
+         */
+        if (GIMP_IS_LAYER (drawable))
+          {
+            parent   = gimp_layer_get_parent (GIMP_LAYER (drawable));
+            position = gimp_item_get_index (GIMP_ITEM (drawable));
+          }
+
+        gimp_image_add_layer (image, layer, parent, position, TRUE);
+      }
+      break;
+    }
+
+  gimp_image_undo_group_end (image);
+
+  return layer;
+}
+
+GimpLayer *
+gimp_edit_paste (GimpImage     *image,
+                 GimpDrawable  *drawable,
+                 GimpObject    *paste,
+                 GimpPasteType  paste_type,
+                 gint           viewport_x,
+                 gint           viewport_y,
+                 gint           viewport_width,
+                 gint           viewport_height)
+{
+  GimpLayer *layer;
+  gint       offset_x = 0;
+  gint       offset_y = 0;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (drawable == NULL || GIMP_IS_DRAWABLE (drawable), NULL);
+  g_return_val_if_fail (drawable == NULL ||
+                        gimp_item_is_attached (GIMP_ITEM (drawable)), NULL);
+  g_return_val_if_fail (GIMP_IS_IMAGE (paste) || GIMP_IS_BUFFER (paste), NULL);
+
+  layer = gimp_edit_paste_get_layer (image, drawable, paste, &paste_type);
+
+  if (! layer)
+    return NULL;
+
+  if (gimp_edit_paste_is_in_place (paste_type))
+    {
+      gimp_edit_paste_get_paste_offset (image, drawable, paste,
+                                        &offset_x,
+                                        &offset_y);
+    }
+  else
+    {
+      gimp_edit_paste_get_viewport_offset (image, drawable, GIMP_OBJECT (layer),
+                                           viewport_x,
+                                           viewport_y,
+                                           viewport_width,
+                                           viewport_height,
+                                           &offset_x,
+                                           &offset_y);
+    }
+
+  return gimp_edit_paste_paste (image, drawable, layer, paste_type,
+                                offset_x, offset_y);
+}
+
+GimpImage *
+gimp_edit_paste_as_new_image (Gimp       *gimp,
+                              GimpObject *paste)
+{
+  GimpImage *image = NULL;
+
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+  g_return_val_if_fail (GIMP_IS_IMAGE (paste) || GIMP_IS_BUFFER (paste), NULL);
+
+  if (GIMP_IS_IMAGE (paste))
+    {
+      image = gimp_image_duplicate (GIMP_IMAGE (paste));
+    }
+  else if (GIMP_IS_BUFFER (paste))
+    {
+      image = gimp_image_new_from_buffer (gimp, GIMP_BUFFER (paste));
+    }
+
+  return image;
+}
+
+const gchar *
+gimp_edit_named_cut (GimpImage     *image,
+                     const gchar   *name,
+                     GimpDrawable  *drawable,
+                     GimpContext   *context,
+                     GError       **error)
+{
+  GimpBuffer *buffer;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (name != NULL, NULL);
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (drawable)), NULL);
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, NULL);
+
+  buffer = gimp_edit_extract (image, GIMP_PICKABLE (drawable),
+                              context, TRUE, error);
+
+  if (buffer)
+    {
+      gimp_object_set_name (GIMP_OBJECT (buffer), name);
+      gimp_container_add (image->gimp->named_buffers, GIMP_OBJECT (buffer));
+      g_object_unref (buffer);
+
+      return gimp_object_get_name (buffer);
+    }
+
+  return NULL;
+}
+
+const gchar *
+gimp_edit_named_copy (GimpImage     *image,
+                      const gchar   *name,
+                      GimpDrawable  *drawable,
+                      GimpContext   *context,
+                      GError       **error)
+{
+  GimpBuffer *buffer;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (name != NULL, NULL);
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (drawable)), NULL);
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, NULL);
+
+  buffer = gimp_edit_extract (image, GIMP_PICKABLE (drawable),
+                              context, FALSE, error);
+
+  if (buffer)
+    {
+      gimp_object_set_name (GIMP_OBJECT (buffer), name);
+      gimp_container_add (image->gimp->named_buffers, GIMP_OBJECT (buffer));
+      g_object_unref (buffer);
+
+      return gimp_object_get_name (buffer);
+    }
+
+  return NULL;
+}
+
+const gchar *
+gimp_edit_named_copy_visible (GimpImage    *image,
+                              const gchar  *name,
+                              GimpContext  *context,
+                              GError      **error)
+{
+  GimpBuffer *buffer;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (name != NULL, NULL);
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, NULL);
+
+  buffer = gimp_edit_extract (image, GIMP_PICKABLE (image),
+                              context, FALSE, error);
+
+  if (buffer)
+    {
+      gimp_object_set_name (GIMP_OBJECT (buffer), name);
+      gimp_container_add (image->gimp->named_buffers, GIMP_OBJECT (buffer));
+      g_object_unref (buffer);
+
+      return gimp_object_get_name (buffer);
+    }
+
+  return NULL;
+}
+
+
+/*  private functions  */
+
+static GimpBuffer *
+gimp_edit_extract (GimpImage     *image,
+                   GimpPickable  *pickable,
+                   GimpContext   *context,
+                   gboolean       cut_pixels,
+                   GError       **error)
+{
+  GeglBuffer *buffer;
+  gint        offset_x;
+  gint        offset_y;
+
+  if (cut_pixels)
+    gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_EDIT_CUT,
+                                 C_("undo-type", "Cut"));
+
+  /*  Cut/copy the mask portion from the image  */
+  buffer = gimp_selection_extract (GIMP_SELECTION (gimp_image_get_mask (image)),
+                                   pickable, context,
+                                   cut_pixels, FALSE, FALSE,
+                                   &offset_x, &offset_y, error);
+
+  if (cut_pixels)
+    gimp_image_undo_group_end (image);
+
+  if (buffer)
+    {
+      GimpBuffer *gimp_buffer;
+      gdouble     res_x;
+      gdouble     res_y;
+
+      gimp_buffer = gimp_buffer_new (buffer, _("Global Buffer"),
+                                     offset_x, offset_y, FALSE);
+      g_object_unref (buffer);
+
+      gimp_image_get_resolution (image, &res_x, &res_y);
+      gimp_buffer_set_resolution (gimp_buffer, res_x, res_y);
+      gimp_buffer_set_unit (gimp_buffer, gimp_image_get_unit (image));
+
+      if (GIMP_IS_COLOR_MANAGED (pickable))
+        {
+          GimpColorProfile *profile =
+            gimp_color_managed_get_color_profile (GIMP_COLOR_MANAGED (pickable));
+
+          if (profile)
+            gimp_buffer_set_color_profile (gimp_buffer, profile);
+        }
+
+      return gimp_buffer;
+    }
+
+  return NULL;
+}
diff --git a/app/core/gimp-edit.h b/app/core/gimp-edit.h
new file mode 100644
index 0000000..c3d8ca5
--- /dev/null
+++ b/app/core/gimp-edit.h
@@ -0,0 +1,61 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_EDIT_H__
+#define __GIMP_EDIT_H__
+
+
+GimpObject  * gimp_edit_cut                (GimpImage       *image,
+                                            GimpDrawable    *drawable,
+                                            GimpContext     *context,
+                                            GError         **error);
+GimpObject  * gimp_edit_copy               (GimpImage       *image,
+                                            GimpDrawable    *drawable,
+                                            GimpContext     *context,
+                                            GError         **error);
+GimpBuffer  * gimp_edit_copy_visible       (GimpImage       *image,
+                                            GimpContext     *context,
+                                            GError         **error);
+
+GimpLayer   * gimp_edit_paste              (GimpImage       *image,
+                                            GimpDrawable    *drawable,
+                                            GimpObject      *paste,
+                                            GimpPasteType    paste_type,
+                                            gint             viewport_x,
+                                            gint             viewport_y,
+                                            gint             viewport_width,
+                                            gint             viewport_height);
+GimpImage   * gimp_edit_paste_as_new_image (Gimp            *gimp,
+                                            GimpObject      *paste);
+
+const gchar * gimp_edit_named_cut          (GimpImage       *image,
+                                            const gchar     *name,
+                                            GimpDrawable    *drawable,
+                                            GimpContext     *context,
+                                            GError         **error);
+const gchar * gimp_edit_named_copy         (GimpImage       *image,
+                                            const gchar     *name,
+                                            GimpDrawable    *drawable,
+                                            GimpContext     *context,
+                                            GError         **error);
+const gchar * gimp_edit_named_copy_visible (GimpImage       *image,
+                                            const gchar     *name,
+                                            GimpContext     *context,
+                                            GError         **error);
+
+
+#endif  /*  __GIMP_EDIT_H__  */
diff --git a/app/core/gimp-filter-history.c b/app/core/gimp-filter-history.c
new file mode 100644
index 0000000..afdd6ed
--- /dev/null
+++ b/app/core/gimp-filter-history.c
@@ -0,0 +1,160 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-2003 Spencer Kimball and Peter Mattis
+ *
+ * gimp-filter-history.c
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+
+#include "core-types.h"
+
+#include "config/gimpcoreconfig.h"
+
+#include "gimp.h"
+#include "gimp-filter-history.h"
+
+#include "pdb/gimpprocedure.h"
+
+
+/*  local function prototypes  */
+
+static gint   gimp_filter_history_compare (GimpProcedure *proc1,
+                                           GimpProcedure *proc2);
+
+
+/*  public functions  */
+
+gint
+gimp_filter_history_size (Gimp *gimp)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), 0);
+
+  return MAX (1, gimp->config->filter_history_size);
+}
+
+gint
+gimp_filter_history_length (Gimp *gimp)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), 0);
+
+  return g_list_length (gimp->filter_history);
+}
+
+GimpProcedure *
+gimp_filter_history_nth (Gimp  *gimp,
+                         gint   n)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  return g_list_nth_data (gimp->filter_history, n);
+}
+
+void
+gimp_filter_history_add (Gimp          *gimp,
+                         GimpProcedure *procedure)
+{
+  GList *link;
+
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+  g_return_if_fail (GIMP_IS_PROCEDURE (procedure));
+
+  /* return early if the procedure is already at the top */
+  if (gimp->filter_history &&
+      gimp_filter_history_compare (gimp->filter_history->data, procedure) == 0)
+    return;
+
+  /* ref new first then unref old, they might be the same */
+  g_object_ref (procedure);
+
+  link = g_list_find_custom (gimp->filter_history, procedure,
+                             (GCompareFunc) gimp_filter_history_compare);
+
+  if (link)
+    {
+      g_object_unref (link->data);
+      gimp->filter_history = g_list_delete_link (gimp->filter_history, link);
+    }
+
+  gimp->filter_history = g_list_prepend (gimp->filter_history, procedure);
+
+  link = g_list_nth (gimp->filter_history, gimp_filter_history_size (gimp));
+
+  if (link)
+    {
+      g_object_unref (link->data);
+      gimp->filter_history = g_list_delete_link (gimp->filter_history, link);
+    }
+
+  gimp_filter_history_changed (gimp);
+}
+
+void
+gimp_filter_history_remove (Gimp          *gimp,
+                            GimpProcedure *procedure)
+{
+  GList *link;
+
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+  g_return_if_fail (GIMP_IS_PROCEDURE (procedure));
+
+  link = g_list_find_custom (gimp->filter_history, procedure,
+                             (GCompareFunc) gimp_filter_history_compare);
+
+  if (link)
+    {
+      g_object_unref (link->data);
+      gimp->filter_history = g_list_delete_link (gimp->filter_history, link);
+
+      gimp_filter_history_changed (gimp);
+    }
+}
+
+void
+gimp_filter_history_clear (Gimp *gimp)
+{
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+
+  if (gimp->filter_history)
+    {
+      g_list_free_full (gimp->filter_history, (GDestroyNotify) g_object_unref);
+      gimp->filter_history = NULL;
+
+      gimp_filter_history_changed (gimp);
+    }
+}
+
+
+/*  private functions  */
+
+static gint
+gimp_filter_history_compare (GimpProcedure *proc1,
+                             GimpProcedure *proc2)
+{
+  /*  the procedures can have the same name, but could still be two
+   *  different filters using the same operation, so also compare
+   *  their menu labels
+   */
+  return (gimp_procedure_name_compare (proc1, proc2) ||
+          strcmp (gimp_procedure_get_menu_label (proc1),
+                  gimp_procedure_get_menu_label (proc2)));
+}
diff --git a/app/core/gimp-filter-history.h b/app/core/gimp-filter-history.h
new file mode 100644
index 0000000..e74b820
--- /dev/null
+++ b/app/core/gimp-filter-history.h
@@ -0,0 +1,35 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimp-filter-history.h
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_FILTER_HISTORY_H__
+#define __GIMP_FILTER_HISTORY_H__
+
+
+gint            gimp_filter_history_size   (Gimp          *gimp);
+gint            gimp_filter_history_length (Gimp          *gimp);
+GimpProcedure * gimp_filter_history_nth    (Gimp          *gimp,
+                                            gint           n);
+void            gimp_filter_history_add    (Gimp          *gimp,
+                                            GimpProcedure *procedure);
+void            gimp_filter_history_remove (Gimp          *gimp,
+                                            GimpProcedure *procedure);
+void            gimp_filter_history_clear  (Gimp          *gimp);
+
+
+#endif /* __GIMP_FILTER_HISTORY_H__ */
diff --git a/app/core/gimp-gradients.c b/app/core/gimp-gradients.c
new file mode 100644
index 0000000..2c4ec0f
--- /dev/null
+++ b/app/core/gimp-gradients.c
@@ -0,0 +1,174 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-2002 Spencer Kimball, Peter Mattis, and others
+ *
+ * gimp-gradients.c
+ * Copyright (C) 2002 Michael Natterer  <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gimp.h"
+#include "gimp-gradients.h"
+#include "gimpcontext.h"
+#include "gimpcontainer.h"
+#include "gimpdatafactory.h"
+#include "gimpgradient.h"
+
+#include "gimp-intl.h"
+
+
+#define CUSTOM_KEY         "gimp-gradient-custom"
+#define FG_BG_RGB_KEY      "gimp-gradient-fg-bg-rgb"
+#define FG_BG_HARDEDGE_KEY "gimp-gradient-fg-bg-rgb-hardedge"
+#define FG_BG_HSV_CCW_KEY  "gimp-gradient-fg-bg-hsv-ccw"
+#define FG_BG_HSV_CW_KEY   "gimp-gradient-fg-bg-hsv-cw"
+#define FG_TRANSPARENT_KEY "gimp-gradient-fg-transparent"
+
+
+/*  local function prototypes  */
+
+static GimpGradient * gimp_gradients_add_gradient (Gimp        *gimp,
+                                                   const gchar *name,
+                                                   const gchar *id);
+
+
+/*  public functions  */
+
+void
+gimp_gradients_init (Gimp *gimp)
+{
+  GimpGradient *gradient;
+
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+
+  /* Custom */
+  gradient = gimp_gradients_add_gradient (gimp,
+                                          _("Custom"),
+                                          CUSTOM_KEY);
+  g_object_set (gradient,
+                "writable", TRUE,
+                NULL);
+  gradient->segments->left_color_type  = GIMP_GRADIENT_COLOR_FOREGROUND;
+  gradient->segments->right_color_type = GIMP_GRADIENT_COLOR_BACKGROUND;
+
+  /* FG to BG (RGB) */
+  gradient = gimp_gradients_add_gradient (gimp,
+                                          _("FG to BG (RGB)"),
+                                          FG_BG_RGB_KEY);
+  gradient->segments->left_color_type  = GIMP_GRADIENT_COLOR_FOREGROUND;
+  gradient->segments->right_color_type = GIMP_GRADIENT_COLOR_BACKGROUND;
+  gimp_context_set_gradient (gimp->user_context, gradient);
+
+  /* FG to BG (Hardedge) */
+  gradient = gimp_gradients_add_gradient (gimp,
+                                          _("FG to BG (Hardedge)"),
+                                          FG_BG_HARDEDGE_KEY);
+  gradient->segments->left_color_type  = GIMP_GRADIENT_COLOR_FOREGROUND;
+  gradient->segments->right_color_type = GIMP_GRADIENT_COLOR_BACKGROUND;
+  gradient->segments->type             = GIMP_GRADIENT_SEGMENT_STEP;
+
+  /* FG to BG (HSV counter-clockwise) */
+  gradient = gimp_gradients_add_gradient (gimp,
+                                          _("FG to BG (HSV counter-clockwise)"),
+                                          FG_BG_HSV_CCW_KEY);
+  gradient->segments->left_color_type  = GIMP_GRADIENT_COLOR_FOREGROUND;
+  gradient->segments->right_color_type = GIMP_GRADIENT_COLOR_BACKGROUND;
+  gradient->segments->color            = GIMP_GRADIENT_SEGMENT_HSV_CCW;
+
+  /* FG to BG (HSV clockwise hue) */
+  gradient = gimp_gradients_add_gradient (gimp,
+                                          _("FG to BG (HSV clockwise hue)"),
+                                          FG_BG_HSV_CW_KEY);
+  gradient->segments->left_color_type  = GIMP_GRADIENT_COLOR_FOREGROUND;
+  gradient->segments->right_color_type = GIMP_GRADIENT_COLOR_BACKGROUND;
+  gradient->segments->color            = GIMP_GRADIENT_SEGMENT_HSV_CW;
+
+  /* FG to Transparent */
+  gradient = gimp_gradients_add_gradient (gimp,
+                                          _("FG to Transparent"),
+                                          FG_TRANSPARENT_KEY);
+  gradient->segments->left_color_type  = GIMP_GRADIENT_COLOR_FOREGROUND;
+  gradient->segments->right_color_type = GIMP_GRADIENT_COLOR_FOREGROUND_TRANSPARENT;
+}
+
+GimpGradient *
+gimp_gradients_get_custom (Gimp *gimp)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  return g_object_get_data (G_OBJECT (gimp), CUSTOM_KEY);
+}
+
+GimpGradient *
+gimp_gradients_get_fg_bg_rgb (Gimp *gimp)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  return g_object_get_data (G_OBJECT (gimp), FG_BG_RGB_KEY);
+}
+
+GimpGradient *
+gimp_gradients_get_fg_bg_hsv_ccw (Gimp *gimp)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  return g_object_get_data (G_OBJECT (gimp), FG_BG_HSV_CCW_KEY);
+}
+
+GimpGradient *
+gimp_gradients_get_fg_bg_hsv_cw (Gimp *gimp)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  return g_object_get_data (G_OBJECT (gimp), FG_BG_HSV_CW_KEY);
+}
+
+GimpGradient *
+gimp_gradients_get_fg_transparent (Gimp *gimp)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  return g_object_get_data (G_OBJECT (gimp), FG_TRANSPARENT_KEY);
+}
+
+
+/*  private functions  */
+
+static GimpGradient *
+gimp_gradients_add_gradient (Gimp        *gimp,
+                             const gchar *name,
+                             const gchar *id)
+{
+  GimpGradient *gradient;
+
+  gradient = GIMP_GRADIENT (gimp_gradient_new (gimp_get_user_context (gimp),
+                                               name));
+
+  gimp_data_make_internal (GIMP_DATA (gradient), id);
+
+  gimp_container_add (gimp_data_factory_get_container (gimp->gradient_factory),
+                      GIMP_OBJECT (gradient));
+  g_object_unref (gradient);
+
+  g_object_set_data (G_OBJECT (gimp), id, gradient);
+
+  return gradient;
+}
diff --git a/app/core/gimp-gradients.h b/app/core/gimp-gradients.h
new file mode 100644
index 0000000..72f21a6
--- /dev/null
+++ b/app/core/gimp-gradients.h
@@ -0,0 +1,34 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-2002 Spencer Kimball, Peter Mattis, and others
+ *
+ * gimp-gradients.h
+ * Copyright (C) 2002 Michael Natterer  <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_GRADIENTS__
+#define __GIMP_GRADIENTS__
+
+
+void           gimp_gradients_init               (Gimp *gimp);
+
+GimpGradient * gimp_gradients_get_custom         (Gimp *gimp);
+GimpGradient * gimp_gradients_get_fg_bg_rgb      (Gimp *gimp);
+GimpGradient * gimp_gradients_get_fg_bg_hsv_ccw  (Gimp *gimp);
+GimpGradient * gimp_gradients_get_fg_bg_hsv_cw   (Gimp *gimp);
+GimpGradient * gimp_gradients_get_fg_transparent (Gimp *gimp);
+
+
+#endif /* __GIMP_GRADIENTS__ */
diff --git a/app/core/gimp-gui.c b/app/core/gimp-gui.c
new file mode 100644
index 0000000..0b0fe42
--- /dev/null
+++ b/app/core/gimp-gui.c
@@ -0,0 +1,585 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-2002 Spencer Kimball, Peter Mattis, and others
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+
+#include "core-types.h"
+
+#include "gimp.h"
+#include "gimp-gui.h"
+#include "gimpcontainer.h"
+#include "gimpcontext.h"
+#include "gimpimage.h"
+#include "gimpprogress.h"
+#include "gimpwaitable.h"
+
+#include "about.h"
+
+#include "gimp-intl.h"
+
+
+void
+gimp_gui_init (Gimp *gimp)
+{
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+
+  gimp->gui.ungrab                 = NULL;
+  gimp->gui.threads_enter          = NULL;
+  gimp->gui.threads_leave          = NULL;
+  gimp->gui.set_busy               = NULL;
+  gimp->gui.unset_busy             = NULL;
+  gimp->gui.show_message           = NULL;
+  gimp->gui.help                   = NULL;
+  gimp->gui.get_program_class      = NULL;
+  gimp->gui.get_display_name       = NULL;
+  gimp->gui.get_user_time          = NULL;
+  gimp->gui.get_theme_dir          = NULL;
+  gimp->gui.get_icon_theme_dir     = NULL;
+  gimp->gui.display_get_by_id      = NULL;
+  gimp->gui.display_get_id         = NULL;
+  gimp->gui.display_get_window_id  = NULL;
+  gimp->gui.display_create         = NULL;
+  gimp->gui.display_delete         = NULL;
+  gimp->gui.displays_reconnect     = NULL;
+  gimp->gui.progress_new           = NULL;
+  gimp->gui.progress_free          = NULL;
+  gimp->gui.pdb_dialog_set         = NULL;
+  gimp->gui.pdb_dialog_close       = NULL;
+  gimp->gui.recent_list_add_file   = NULL;
+  gimp->gui.recent_list_load       = NULL;
+  gimp->gui.get_mount_operation    = NULL;
+  gimp->gui.query_profile_policy   = NULL;
+}
+
+void
+gimp_gui_ungrab (Gimp *gimp)
+{
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+
+  if (gimp->gui.ungrab)
+    gimp->gui.ungrab (gimp);
+}
+
+void
+gimp_threads_enter (Gimp *gimp)
+{
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+
+  if (gimp->gui.threads_enter)
+    gimp->gui.threads_enter (gimp);
+}
+
+void
+gimp_threads_leave (Gimp *gimp)
+{
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+
+  if (gimp->gui.threads_leave)
+    gimp->gui.threads_leave (gimp);
+}
+
+void
+gimp_set_busy (Gimp *gimp)
+{
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+
+  /* FIXME: gimp_busy HACK */
+  gimp->busy++;
+
+  if (gimp->busy == 1)
+    {
+      if (gimp->gui.set_busy)
+        gimp->gui.set_busy (gimp);
+    }
+}
+
+static gboolean
+gimp_idle_unset_busy (gpointer data)
+{
+  Gimp *gimp = data;
+
+  gimp_unset_busy (gimp);
+
+  gimp->busy_idle_id = 0;
+
+  return FALSE;
+}
+
+void
+gimp_set_busy_until_idle (Gimp *gimp)
+{
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+
+  if (! gimp->busy_idle_id)
+    {
+      gimp_set_busy (gimp);
+
+      gimp->busy_idle_id = g_idle_add_full (G_PRIORITY_HIGH,
+                                            gimp_idle_unset_busy, gimp,
+                                            NULL);
+    }
+}
+
+void
+gimp_unset_busy (Gimp *gimp)
+{
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+  g_return_if_fail (gimp->busy > 0);
+
+  /* FIXME: gimp_busy HACK */
+  gimp->busy--;
+
+  if (gimp->busy == 0)
+    {
+      if (gimp->gui.unset_busy)
+        gimp->gui.unset_busy (gimp);
+    }
+}
+
+void
+gimp_show_message (Gimp                *gimp,
+                   GObject             *handler,
+                   GimpMessageSeverity  severity,
+                   const gchar         *domain,
+                   const gchar         *message)
+{
+  const gchar *desc = (severity == GIMP_MESSAGE_ERROR) ? "Error" : "Message";
+
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+  g_return_if_fail (handler == NULL || G_IS_OBJECT (handler));
+  g_return_if_fail (message != NULL);
+
+  if (! domain)
+    domain = GIMP_ACRONYM;
+
+  if (! gimp->console_messages)
+    {
+      if (gimp->gui.show_message)
+        {
+          gimp->gui.show_message (gimp, handler, severity,
+                                  domain, message);
+          return;
+        }
+      else if (GIMP_IS_PROGRESS (handler) &&
+               gimp_progress_message (GIMP_PROGRESS (handler), gimp,
+                                      severity, domain, message))
+        {
+          /* message has been handled by GimpProgress */
+          return;
+        }
+    }
+
+  gimp_enum_get_value (GIMP_TYPE_MESSAGE_SEVERITY, severity,
+                       NULL, NULL, &desc, NULL);
+  g_printerr ("%s-%s: %s\n\n", domain, desc, message);
+}
+
+void
+gimp_wait (Gimp         *gimp,
+           GimpWaitable *waitable,
+           const gchar  *format,
+           ...)
+{
+  va_list  args;
+  gchar   *message;
+
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+  g_return_if_fail (GIMP_IS_WAITABLE (waitable));
+  g_return_if_fail (format != NULL);
+
+  if (gimp_waitable_wait_for (waitable, 0.5 * G_TIME_SPAN_SECOND))
+    return;
+
+  va_start (args, format);
+
+  message = g_strdup_vprintf (format, args);
+
+  va_end (args);
+
+  if (! gimp->console_messages &&
+      gimp->gui.wait           &&
+      gimp->gui.wait (gimp, waitable, message))
+    {
+      return;
+    }
+
+  /* Translator:  This message is displayed while GIMP is waiting for
+   * some operation to finish.  The %s argument is a message describing
+   * the operation.
+   */
+  g_printerr (_("Please wait: %s\n"), message);
+
+  gimp_waitable_wait (waitable);
+
+  g_free (message);
+}
+
+void
+gimp_help (Gimp         *gimp,
+           GimpProgress *progress,
+           const gchar  *help_domain,
+           const gchar  *help_id)
+{
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+  g_return_if_fail (progress == NULL || GIMP_IS_PROGRESS (progress));
+
+  if (gimp->gui.help)
+    gimp->gui.help (gimp, progress, help_domain, help_id);
+}
+
+const gchar *
+gimp_get_program_class (Gimp *gimp)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  if (gimp->gui.get_program_class)
+    return gimp->gui.get_program_class (gimp);
+
+  return NULL;
+}
+
+gchar *
+gimp_get_display_name (Gimp     *gimp,
+                       gint      display_ID,
+                       GObject **screen,
+                       gint     *monitor)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+  g_return_val_if_fail (screen != NULL, NULL);
+  g_return_val_if_fail (monitor != NULL, NULL);
+
+  if (gimp->gui.get_display_name)
+    return gimp->gui.get_display_name (gimp, display_ID, screen, monitor);
+
+  *screen  = NULL;
+  *monitor = 0;
+
+  return NULL;
+}
+
+/**
+ * gimp_get_user_time:
+ * @gimp:
+ *
+ * Returns the timestamp of the last user interaction. The timestamp is
+ * taken from events caused by user interaction such as key presses or
+ * pointer movements. See gdk_x11_display_get_user_time().
+ *
+ * Return value: the timestamp of the last user interaction
+ */
+guint32
+gimp_get_user_time (Gimp *gimp)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), 0);
+
+  if (gimp->gui.get_user_time)
+    return gimp->gui.get_user_time (gimp);
+
+  return 0;
+}
+
+GFile *
+gimp_get_theme_dir (Gimp *gimp)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  if (gimp->gui.get_theme_dir)
+    return gimp->gui.get_theme_dir (gimp);
+
+  return NULL;
+}
+
+GFile *
+gimp_get_icon_theme_dir (Gimp *gimp)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  if (gimp->gui.get_icon_theme_dir)
+    return gimp->gui.get_icon_theme_dir (gimp);
+
+  return NULL;
+}
+
+GimpObject *
+gimp_get_window_strategy (Gimp *gimp)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  if (gimp->gui.get_window_strategy)
+    return gimp->gui.get_window_strategy (gimp);
+
+  return NULL;
+}
+
+GimpObject *
+gimp_get_empty_display (Gimp *gimp)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  if (gimp->gui.get_empty_display)
+    return gimp->gui.get_empty_display (gimp);
+
+  return NULL;
+}
+
+GimpObject *
+gimp_get_display_by_ID (Gimp *gimp,
+                        gint  ID)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  if (gimp->gui.display_get_by_id)
+    return gimp->gui.display_get_by_id (gimp, ID);
+
+  return NULL;
+}
+
+gint
+gimp_get_display_ID (Gimp       *gimp,
+                     GimpObject *display)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), -1);
+  g_return_val_if_fail (GIMP_IS_OBJECT (display), -1);
+
+  if (gimp->gui.display_get_id)
+    return gimp->gui.display_get_id (display);
+
+  return -1;
+}
+
+guint32
+gimp_get_display_window_id (Gimp       *gimp,
+                            GimpObject *display)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), -1);
+  g_return_val_if_fail (GIMP_IS_OBJECT (display), -1);
+
+  if (gimp->gui.display_get_window_id)
+    return gimp->gui.display_get_window_id (display);
+
+  return -1;
+}
+
+GimpObject *
+gimp_create_display (Gimp      *gimp,
+                     GimpImage *image,
+                     GimpUnit   unit,
+                     gdouble    scale,
+                     GObject   *screen,
+                     gint       monitor)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+  g_return_val_if_fail (image == NULL || GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (screen == NULL || G_IS_OBJECT (screen), NULL);
+
+  if (gimp->gui.display_create)
+    return gimp->gui.display_create (gimp, image, unit, scale, screen, monitor);
+
+  return NULL;
+}
+
+void
+gimp_delete_display (Gimp       *gimp,
+                     GimpObject *display)
+{
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+  g_return_if_fail (GIMP_IS_OBJECT (display));
+
+  if (gimp->gui.display_delete)
+    gimp->gui.display_delete (display);
+}
+
+void
+gimp_reconnect_displays (Gimp      *gimp,
+                         GimpImage *old_image,
+                         GimpImage *new_image)
+{
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+  g_return_if_fail (GIMP_IS_IMAGE (old_image));
+  g_return_if_fail (GIMP_IS_IMAGE (new_image));
+
+  if (gimp->gui.displays_reconnect)
+    gimp->gui.displays_reconnect (gimp, old_image, new_image);
+}
+
+GimpProgress *
+gimp_new_progress (Gimp       *gimp,
+                   GimpObject *display)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+  g_return_val_if_fail (display == NULL || GIMP_IS_OBJECT (display), NULL);
+
+  if (gimp->gui.progress_new)
+    return gimp->gui.progress_new (gimp, display);
+
+  return NULL;
+}
+
+void
+gimp_free_progress (Gimp         *gimp,
+                    GimpProgress *progress)
+{
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+  g_return_if_fail (GIMP_IS_PROGRESS (progress));
+
+  if (gimp->gui.progress_free)
+    gimp->gui.progress_free (gimp, progress);
+}
+
+gboolean
+gimp_pdb_dialog_new (Gimp          *gimp,
+                     GimpContext   *context,
+                     GimpProgress  *progress,
+                     GimpContainer *container,
+                     const gchar   *title,
+                     const gchar   *callback_name,
+                     const gchar   *object_name,
+                     ...)
+{
+  gboolean retval = FALSE;
+
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), FALSE);
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), FALSE);
+  g_return_val_if_fail (progress == NULL || GIMP_IS_PROGRESS (progress), FALSE);
+  g_return_val_if_fail (GIMP_IS_CONTAINER (container), FALSE);
+  g_return_val_if_fail (title != NULL, FALSE);
+  g_return_val_if_fail (callback_name != NULL, FALSE);
+
+  if (gimp->gui.pdb_dialog_new)
+    {
+      va_list args;
+
+      va_start (args, object_name);
+
+      retval = gimp->gui.pdb_dialog_new (gimp, context, progress,
+                                         container, title,
+                                         callback_name, object_name,
+                                         args);
+
+      va_end (args);
+    }
+
+  return retval;
+}
+
+gboolean
+gimp_pdb_dialog_set (Gimp          *gimp,
+                     GimpContainer *container,
+                     const gchar   *callback_name,
+                     const gchar   *object_name,
+                     ...)
+{
+  gboolean retval = FALSE;
+
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), FALSE);
+  g_return_val_if_fail (GIMP_IS_CONTAINER (container), FALSE);
+  g_return_val_if_fail (callback_name != NULL, FALSE);
+  g_return_val_if_fail (object_name != NULL, FALSE);
+
+  if (gimp->gui.pdb_dialog_set)
+    {
+      va_list args;
+
+      va_start (args, object_name);
+
+      retval = gimp->gui.pdb_dialog_set (gimp, container, callback_name,
+                                         object_name, args);
+
+      va_end (args);
+    }
+
+  return retval;
+}
+
+gboolean
+gimp_pdb_dialog_close (Gimp          *gimp,
+                       GimpContainer *container,
+                       const gchar   *callback_name)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), FALSE);
+  g_return_val_if_fail (GIMP_IS_CONTAINER (container), FALSE);
+  g_return_val_if_fail (callback_name != NULL, FALSE);
+
+  if (gimp->gui.pdb_dialog_close)
+    return gimp->gui.pdb_dialog_close (gimp, container, callback_name);
+
+  return FALSE;
+}
+
+gboolean
+gimp_recent_list_add_file (Gimp        *gimp,
+                           GFile       *file,
+                           const gchar *mime_type)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), FALSE);
+  g_return_val_if_fail (G_IS_FILE (file), FALSE);
+
+  if (gimp->gui.recent_list_add_file)
+    return gimp->gui.recent_list_add_file (gimp, file, mime_type);
+
+  return FALSE;
+}
+
+void
+gimp_recent_list_load (Gimp *gimp)
+{
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+
+  if (gimp->gui.recent_list_load)
+    gimp->gui.recent_list_load (gimp);
+}
+
+GMountOperation *
+gimp_get_mount_operation (Gimp         *gimp,
+                          GimpProgress *progress)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), FALSE);
+  g_return_val_if_fail (progress == NULL || GIMP_IS_PROGRESS (progress), FALSE);
+
+  if (gimp->gui.get_mount_operation)
+    return gimp->gui.get_mount_operation (gimp, progress);
+
+  return g_mount_operation_new ();
+}
+
+GimpColorProfilePolicy
+gimp_query_profile_policy (Gimp                      *gimp,
+                           GimpImage                 *image,
+                           GimpContext               *context,
+                           GimpColorProfile         **dest_profile,
+                           GimpColorRenderingIntent  *intent,
+                           gboolean                  *bpc,
+                           gboolean                  *dont_ask)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), GIMP_COLOR_PROFILE_POLICY_KEEP);
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), GIMP_COLOR_PROFILE_POLICY_KEEP);
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), GIMP_COLOR_PROFILE_POLICY_KEEP);
+  g_return_val_if_fail (dest_profile != NULL, GIMP_COLOR_PROFILE_POLICY_KEEP);
+
+  if (gimp->gui.query_profile_policy)
+    return gimp->gui.query_profile_policy (gimp, image, context,
+                                           dest_profile,
+                                           intent, bpc,
+                                           dont_ask);
+
+  return GIMP_COLOR_PROFILE_POLICY_KEEP;
+}
diff --git a/app/core/gimp-gui.h b/app/core/gimp-gui.h
new file mode 100644
index 0000000..49f2761
--- /dev/null
+++ b/app/core/gimp-gui.h
@@ -0,0 +1,211 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1997 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_GUI_H__
+#define __GIMP_GUI_H__
+
+
+typedef struct _GimpGui GimpGui;
+
+struct _GimpGui
+{
+  void           (* ungrab)                 (Gimp                *gimp);
+
+  void           (* threads_enter)          (Gimp                *gimp);
+  void           (* threads_leave)          (Gimp                *gimp);
+
+  void           (* set_busy)               (Gimp                *gimp);
+  void           (* unset_busy)             (Gimp                *gimp);
+
+  void           (* show_message)           (Gimp                *gimp,
+                                             GObject             *handler,
+                                             GimpMessageSeverity  severity,
+                                             const gchar         *domain,
+                                             const gchar         *message);
+  void           (* help)                   (Gimp                *gimp,
+                                             GimpProgress        *progress,
+                                             const gchar         *help_domain,
+                                             const gchar         *help_id);
+
+  gboolean       (* wait)                   (Gimp                *gimp,
+                                             GimpWaitable        *waitable,
+                                             const gchar         *message);
+
+  const gchar  * (* get_program_class)      (Gimp                *gimp);
+  gchar        * (* get_display_name)       (Gimp                *gimp,
+                                             gint                 display_ID,
+                                             GObject            **screen,
+                                             gint                *monitor);
+  guint32        (* get_user_time)          (Gimp                *gimp);
+
+  GFile        * (* get_theme_dir)          (Gimp                *gimp);
+  GFile        * (* get_icon_theme_dir)     (Gimp                *gimp);
+
+  GimpObject   * (* get_window_strategy)    (Gimp                *gimp);
+  GimpObject   * (* get_empty_display)      (Gimp                *gimp);
+  GimpObject   * (* display_get_by_id)      (Gimp                *gimp,
+                                             gint                 ID);
+  gint           (* display_get_id)         (GimpObject          *display);
+  guint32        (* display_get_window_id)  (GimpObject          *display);
+  GimpObject   * (* display_create)         (Gimp                *gimp,
+                                             GimpImage           *image,
+                                             GimpUnit             unit,
+                                             gdouble              scale,
+                                             GObject             *screen,
+                                             gint                 monitor);
+  void           (* display_delete)         (GimpObject          *display);
+  void           (* displays_reconnect)     (Gimp                *gimp,
+                                             GimpImage           *old_image,
+                                             GimpImage           *new_image);
+
+  GimpProgress * (* progress_new)           (Gimp                *gimp,
+                                             GimpObject          *display);
+  void           (* progress_free)          (Gimp                *gimp,
+                                             GimpProgress        *progress);
+
+  gboolean       (* pdb_dialog_new)         (Gimp                *gimp,
+                                             GimpContext         *context,
+                                             GimpProgress        *progress,
+                                             GimpContainer       *container,
+                                             const gchar         *title,
+                                             const gchar         *callback_name,
+                                             const gchar         *object_name,
+                                             va_list              args);
+  gboolean       (* pdb_dialog_set)         (Gimp                *gimp,
+                                             GimpContainer       *container,
+                                             const gchar         *callback_name,
+                                             const gchar         *object_name,
+                                             va_list              args);
+  gboolean       (* pdb_dialog_close)       (Gimp                *gimp,
+                                             GimpContainer       *container,
+                                             const gchar         *callback_name);
+  gboolean       (* recent_list_add_file)   (Gimp                *gimp,
+                                             GFile               *file,
+                                             const gchar         *mime_type);
+  void           (* recent_list_load)       (Gimp                *gimp);
+
+  GMountOperation
+               * (* get_mount_operation)    (Gimp                *gimp,
+                                             GimpProgress        *progress);
+
+  GimpColorProfilePolicy
+                 (* query_profile_policy)   (Gimp                *gimp,
+                                             GimpImage           *image,
+                                             GimpContext         *context,
+                                             GimpColorProfile   **dest_profile,
+                                             GimpColorRenderingIntent *intent,
+                                             gboolean            *bpc,
+                                             gboolean            *dont_ask);
+};
+
+
+void           gimp_gui_init               (Gimp                *gimp);
+
+void           gimp_gui_ungrab             (Gimp                *gimp);
+
+void           gimp_threads_enter          (Gimp                *gimp);
+void           gimp_threads_leave          (Gimp                *gimp);
+
+GimpObject   * gimp_get_window_strategy    (Gimp                *gimp);
+GimpObject   * gimp_get_empty_display      (Gimp                *gimp);
+GimpObject   * gimp_get_display_by_ID      (Gimp                *gimp,
+                                            gint                 ID);
+gint           gimp_get_display_ID         (Gimp                *gimp,
+                                            GimpObject          *display);
+guint32        gimp_get_display_window_id  (Gimp                *gimp,
+                                            GimpObject          *display);
+GimpObject   * gimp_create_display         (Gimp                *gimp,
+                                            GimpImage           *image,
+                                            GimpUnit             unit,
+                                            gdouble              scale,
+                                            GObject             *screen,
+                                            gint                 monitor);
+void           gimp_delete_display         (Gimp                *gimp,
+                                            GimpObject          *display);
+void           gimp_reconnect_displays     (Gimp                *gimp,
+                                            GimpImage           *old_image,
+                                            GimpImage           *new_image);
+
+void           gimp_set_busy               (Gimp                *gimp);
+void           gimp_set_busy_until_idle    (Gimp                *gimp);
+void           gimp_unset_busy             (Gimp                *gimp);
+
+void           gimp_show_message           (Gimp                *gimp,
+                                            GObject             *handler,
+                                            GimpMessageSeverity  severity,
+                                            const gchar         *domain,
+                                            const gchar         *message);
+void           gimp_help                   (Gimp                *gimp,
+                                            GimpProgress        *progress,
+                                            const gchar         *help_domain,
+                                            const gchar         *help_id);
+
+void           gimp_wait                   (Gimp                *gimp,
+                                            GimpWaitable        *waitable,
+                                            const gchar         *format,
+                                            ...) G_GNUC_PRINTF (3, 4);
+
+GimpProgress * gimp_new_progress           (Gimp                *gimp,
+                                            GimpObject          *display);
+void           gimp_free_progress          (Gimp                *gimp,
+                                            GimpProgress        *progress);
+
+const gchar  * gimp_get_program_class      (Gimp                *gimp);
+gchar        * gimp_get_display_name       (Gimp                *gimp,
+                                            gint                 display_ID,
+                                            GObject            **screen,
+                                            gint                *monitor);
+guint32        gimp_get_user_time          (Gimp                *gimp);
+GFile        * gimp_get_theme_dir          (Gimp                *gimp);
+GFile        * gimp_get_icon_theme_dir     (Gimp                *gimp);
+
+gboolean       gimp_pdb_dialog_new         (Gimp                *gimp,
+                                            GimpContext         *context,
+                                            GimpProgress        *progress,
+                                            GimpContainer       *container,
+                                            const gchar         *title,
+                                            const gchar         *callback_name,
+                                            const gchar         *object_name,
+                                            ...) G_GNUC_NULL_TERMINATED;
+gboolean       gimp_pdb_dialog_set         (Gimp                *gimp,
+                                            GimpContainer       *container,
+                                            const gchar         *callback_name,
+                                            const gchar         *object_name,
+                                            ...) G_GNUC_NULL_TERMINATED;
+gboolean       gimp_pdb_dialog_close       (Gimp                *gimp,
+                                            GimpContainer       *container,
+                                            const gchar         *callback_name);
+gboolean       gimp_recent_list_add_file   (Gimp                *gimp,
+                                            GFile               *file,
+                                            const gchar         *mime_type);
+void           gimp_recent_list_load       (Gimp                *gimp);
+
+GMountOperation
+             * gimp_get_mount_operation    (Gimp                *gimp,
+                                            GimpProgress        *progress);
+
+GimpColorProfilePolicy
+               gimp_query_profile_policy   (Gimp                *gimp,
+                                            GimpImage           *image,
+                                            GimpContext         *context,
+                                            GimpColorProfile   **dest_profile,
+                                            GimpColorRenderingIntent *intent,
+                                            gboolean            *bpc,
+                                            gboolean            *dont_ask);
+
+
+#endif  /* __GIMP_GUI_H__ */
diff --git a/app/core/gimp-internal-data.c b/app/core/gimp-internal-data.c
new file mode 100644
index 0000000..6653946
--- /dev/null
+++ b/app/core/gimp-internal-data.c
@@ -0,0 +1,346 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-2002 Spencer Kimball, Peter Mattis, and others
+ *
+ * gimp-internal-data.c
+ * Copyright (C) 2017 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+
+#include "core-types.h"
+
+#include "gimp.h"
+#include "gimp-gradients.h"
+#include "gimp-internal-data.h"
+#include "gimpdata.h"
+#include "gimpdataloaderfactory.h"
+#include "gimperror.h"
+#include "gimpgradient-load.h"
+
+#include "gimp-intl.h"
+
+
+#define GIMP_INTERNAL_DATA_DIRECTORY "internal-data"
+
+
+typedef GimpData * (* GimpDataGetFunc) (Gimp *gimp);
+
+
+typedef struct _GimpInternalDataFile GimpInternalDataFile;
+
+struct _GimpInternalDataFile
+{
+  const gchar      *name;
+  GimpDataGetFunc   get_func;
+  GimpDataLoadFunc  load_func;
+};
+
+
+/*  local function prototypes  */
+
+static gboolean   gimp_internal_data_create_directory (GError                     **error);
+
+static GFile    * gimp_internal_data_get_file         (const GimpInternalDataFile  *data_file);
+
+static gboolean   gimp_internal_data_load_data_file   (Gimp                        *gimp,
+                                                       const GimpInternalDataFile  *data_file,
+                                                       GError                     **error);
+static gboolean   gimp_internal_data_save_data_file   (Gimp                        *gimp,
+                                                       const GimpInternalDataFile  *data_file,
+                                                       GError                     **error);
+static gboolean   gimp_internal_data_delete_data_file (Gimp                        *gimp,
+                                                       const GimpInternalDataFile  *data_file,
+                                                       GError                     **error);
+
+/*  static variables  */
+
+static const GimpInternalDataFile internal_data_files[] =
+{
+  /* Custom gradient */
+  {
+    .name      = "custom" GIMP_GRADIENT_FILE_EXTENSION,
+    .get_func  = (GimpDataGetFunc) gimp_gradients_get_custom,
+    .load_func = gimp_gradient_load
+  }
+};
+
+
+/*  public functions  */
+
+gboolean
+gimp_internal_data_load (Gimp    *gimp,
+                         GError **error)
+{
+  gint i;
+
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  for (i = 0; i < G_N_ELEMENTS (internal_data_files); i++)
+    {
+      const GimpInternalDataFile *data_file = &internal_data_files[i];
+
+      if (! gimp_internal_data_load_data_file (gimp, data_file, error))
+        return FALSE;
+    }
+
+  return TRUE;
+}
+
+gboolean
+gimp_internal_data_save (Gimp    *gimp,
+                         GError **error)
+{
+  gint i;
+
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  if (! gimp_internal_data_create_directory (error))
+    return FALSE;
+
+  for (i = 0; i < G_N_ELEMENTS (internal_data_files); i++)
+    {
+      const GimpInternalDataFile *data_file = &internal_data_files[i];
+
+      if (! gimp_internal_data_save_data_file (gimp, data_file, error))
+        return FALSE;
+    }
+
+  return TRUE;
+}
+
+gboolean
+gimp_internal_data_clear (Gimp    *gimp,
+                          GError **error)
+{
+  gint i;
+
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  for (i = 0; i < G_N_ELEMENTS (internal_data_files); i++)
+    {
+      const GimpInternalDataFile *data_file = &internal_data_files[i];
+
+      if (! gimp_internal_data_delete_data_file (gimp, data_file, error))
+        return FALSE;
+    }
+
+  return TRUE;
+}
+
+
+/*  private functions  */
+
+static gboolean
+gimp_internal_data_create_directory (GError **error)
+{
+  GFile    *directory;
+  GError   *my_error = NULL;
+  gboolean  success;
+
+  directory = gimp_directory_file (GIMP_INTERNAL_DATA_DIRECTORY, NULL);
+
+  success = g_file_make_directory (directory, NULL, &my_error);
+
+  g_object_unref (directory);
+
+  if (! success)
+    {
+      if (my_error->code == G_IO_ERROR_EXISTS)
+        {
+          g_clear_error (&my_error);
+          success = TRUE;
+        }
+      else
+        {
+          g_propagate_error (error, my_error);
+        }
+    }
+
+  return success;
+}
+
+static GFile *
+gimp_internal_data_get_file (const GimpInternalDataFile *data_file)
+{
+  return gimp_directory_file (GIMP_INTERNAL_DATA_DIRECTORY,
+                              data_file->name,
+                              NULL);
+}
+
+static gboolean
+gimp_internal_data_load_data_file (Gimp                        *gimp,
+                                   const GimpInternalDataFile  *data_file,
+                                   GError                     **error)
+{
+  GFile        *file;
+  GInputStream *input;
+  GimpData     *data;
+  GList        *list;
+  GError       *my_error = NULL;
+
+  file = gimp_internal_data_get_file (data_file);
+
+  if (gimp->be_verbose)
+    g_print ("Parsing '%s'\n", gimp_file_get_utf8_name (file));
+
+  input = G_INPUT_STREAM (g_file_read (file, NULL, &my_error));
+
+  if (! input)
+    {
+      g_object_unref (file);
+
+      if (my_error->code == G_IO_ERROR_NOT_FOUND)
+        {
+          g_clear_error (&my_error);
+          return TRUE;
+        }
+      else
+        {
+          g_propagate_error (error, my_error);
+          return FALSE;
+        }
+    }
+
+  list = data_file->load_func (gimp->user_context, file, input, error);
+
+  g_object_unref (input);
+  g_object_unref (file);
+
+  if (! list)
+    return FALSE;
+
+  data = data_file->get_func (gimp);
+
+  gimp_data_copy (data, GIMP_DATA (list->data));
+
+  g_list_free_full (list, g_object_unref);
+
+  return TRUE;
+}
+
+static gboolean
+gimp_internal_data_save_data_file (Gimp                        *gimp,
+                                   const GimpInternalDataFile  *data_file,
+                                   GError                     **error)
+{
+  GFile         *file;
+  GOutputStream *output;
+  GimpData      *data;
+  gboolean       success;
+
+  file = gimp_internal_data_get_file (data_file);
+
+  if (gimp->be_verbose)
+    g_print ("Writing '%s'\n", gimp_file_get_utf8_name (file));
+
+  output = G_OUTPUT_STREAM (g_file_replace (file, NULL, FALSE,
+                                            G_FILE_CREATE_NONE,
+                                            NULL, error));
+
+  if (! output)
+    {
+      g_object_unref (file);
+
+      return FALSE;
+    }
+
+  data = data_file->get_func (gimp);
+
+  /* we bypass gimp_data_save() and call the data's save() virtual function
+   * directly, since gimp_data_save() is a nop for internal data.
+   *
+   * FIXME:  we save the data whether it's dirty or not, since it might not
+   * exist on disk.  currently, we only use this for cheap data, such as
+   * gradients, so this is not a big concern, but if we save more expensive
+   * data in the future, we should fix this.
+   */
+  gimp_assert (GIMP_DATA_GET_CLASS (data)->save);
+  success = GIMP_DATA_GET_CLASS (data)->save (data, output, error);
+
+  if (success)
+    {
+      if (! g_output_stream_close (output, NULL, error))
+        {
+          g_prefix_error (error,
+                          _("Error saving '%s': "),
+                          gimp_file_get_utf8_name (file));
+          success = FALSE;
+        }
+    }
+  else
+    {
+      GCancellable *cancellable = g_cancellable_new ();
+
+      g_cancellable_cancel (cancellable);
+      if (error && *error)
+        {
+          g_prefix_error (error,
+                          _("Error saving '%s': "),
+                          gimp_file_get_utf8_name (file));
+        }
+      else
+        {
+          g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_WRITE,
+                       _("Error saving '%s'"),
+                       gimp_file_get_utf8_name (file));
+        }
+      g_output_stream_close (output, cancellable, NULL);
+      g_object_unref (cancellable);
+    }
+
+  g_object_unref (output);
+  g_object_unref (file);
+
+  return success;
+}
+
+static gboolean
+gimp_internal_data_delete_data_file (Gimp                        *gimp,
+                                     const GimpInternalDataFile  *data_file,
+                                     GError                     **error)
+{
+  GFile    *file;
+  GError   *my_error = NULL;
+  gboolean  success  = TRUE;
+
+  file = gimp_internal_data_get_file (data_file);
+
+  if (gimp->be_verbose)
+    g_print ("Deleting '%s'\n", gimp_file_get_utf8_name (file));
+
+  if (! g_file_delete (file, NULL, &my_error) &&
+      my_error->code != G_IO_ERROR_NOT_FOUND)
+    {
+      success = FALSE;
+
+      g_set_error (error, GIMP_ERROR, GIMP_FAILED,
+                   _("Deleting \"%s\" failed: %s"),
+                   gimp_file_get_utf8_name (file), my_error->message);
+    }
+
+  g_clear_error (&my_error);
+  g_object_unref (file);
+
+  return success;
+}
diff --git a/app/core/gimp-internal-data.h b/app/core/gimp-internal-data.h
new file mode 100644
index 0000000..93f42dd
--- /dev/null
+++ b/app/core/gimp-internal-data.h
@@ -0,0 +1,34 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-2002 Spencer Kimball, Peter Mattis, and others
+ *
+ * gimp-internal-data.h
+ * Copyright (C) 2017 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_INTERNAL_DATA__
+#define __GIMP_INTERNAL_DATA__
+
+
+gboolean   gimp_internal_data_load  (Gimp    *gimp,
+                                     GError **error);
+gboolean   gimp_internal_data_save  (Gimp    *gimp,
+                                     GError **error);
+
+gboolean   gimp_internal_data_clear (Gimp    *gimp,
+                                     GError **error);
+
+
+#endif /* __GIMP_INTERNAL_DATA__ */
diff --git a/app/core/gimp-memsize.c b/app/core/gimp-memsize.c
new file mode 100644
index 0000000..df71737
--- /dev/null
+++ b/app/core/gimp-memsize.c
@@ -0,0 +1,341 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <cairo.h>
+#include <gegl.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpmath/gimpmath.h"
+#include "libgimpcolor/gimpcolor.h"
+
+#include "core-types.h"
+
+#include "gimp-memsize.h"
+#include "gimpparamspecs.h"
+
+
+gint64
+gimp_g_type_instance_get_memsize (GTypeInstance *instance)
+{
+  if (instance)
+    {
+      GTypeQuery type_query;
+
+      g_type_query (G_TYPE_FROM_INSTANCE (instance), &type_query);
+
+      return type_query.instance_size;
+    }
+
+  return 0;
+}
+
+gint64
+gimp_g_object_get_memsize (GObject *object)
+{
+  if (object)
+    return gimp_g_type_instance_get_memsize ((GTypeInstance *) object);
+
+  return 0;
+}
+
+gint64
+gimp_g_hash_table_get_memsize (GHashTable *hash,
+                               gint64      data_size)
+{
+  if (hash)
+    return (2 * sizeof (gint) +
+            5 * sizeof (gpointer) +
+            g_hash_table_size (hash) * (3 * sizeof (gpointer) + data_size));
+
+  return 0;
+}
+
+typedef struct
+{
+  GimpMemsizeFunc func;
+  gint64          memsize;
+  gint64          gui_size;
+} HashMemsize;
+
+static void
+hash_memsize_foreach (gpointer     key,
+                      gpointer     value,
+                      HashMemsize *memsize)
+{
+  gint64 gui_size = 0;
+
+  memsize->memsize  += memsize->func (value, &gui_size);
+  memsize->gui_size += gui_size;
+}
+
+gint64
+gimp_g_hash_table_get_memsize_foreach (GHashTable      *hash,
+                                       GimpMemsizeFunc  func,
+                                       gint64          *gui_size)
+{
+  HashMemsize memsize;
+
+  g_return_val_if_fail (func != NULL, 0);
+
+  if (! hash)
+    return 0;
+
+  memsize.func     = func;
+  memsize.memsize  = 0;
+  memsize.gui_size = 0;
+
+  g_hash_table_foreach (hash, (GHFunc) hash_memsize_foreach, &memsize);
+
+  if (gui_size)
+    *gui_size = memsize.gui_size;
+
+  return memsize.memsize + gimp_g_hash_table_get_memsize (hash, 0);
+}
+
+gint64
+gimp_g_slist_get_memsize (GSList  *slist,
+                          gint64   data_size)
+{
+  return g_slist_length (slist) * (data_size + sizeof (GSList));
+}
+
+gint64
+gimp_g_slist_get_memsize_foreach (GSList          *slist,
+                                  GimpMemsizeFunc  func,
+                                  gint64          *gui_size)
+{
+  GSList *l;
+  gint64  memsize = 0;
+
+  g_return_val_if_fail (func != NULL, 0);
+
+  for (l = slist; l; l = g_slist_next (l))
+    memsize += sizeof (GSList) + func (l->data, gui_size);
+
+  return memsize;
+}
+
+gint64
+gimp_g_list_get_memsize (GList  *list,
+                         gint64  data_size)
+{
+  return g_list_length (list) * (data_size + sizeof (GList));
+}
+
+gint64
+gimp_g_list_get_memsize_foreach (GList           *list,
+                                 GimpMemsizeFunc  func,
+                                 gint64          *gui_size)
+{
+  GList  *l;
+  gint64  memsize = 0;
+
+  g_return_val_if_fail (func != NULL, 0);
+
+  for (l = list; l; l = g_list_next (l))
+    memsize += sizeof (GList) + func (l->data, gui_size);
+
+  return memsize;
+}
+
+gint64
+gimp_g_queue_get_memsize (GQueue *queue,
+                          gint64  data_size)
+{
+  if (queue)
+    {
+      return sizeof (GQueue) +
+             g_queue_get_length (queue) * (data_size + sizeof (GList));
+    }
+
+  return 0;
+}
+
+gint64
+gimp_g_queue_get_memsize_foreach (GQueue          *queue,
+                                  GimpMemsizeFunc  func,
+                                  gint64          *gui_size)
+{
+  gint64 memsize = 0;
+
+  g_return_val_if_fail (func != NULL, 0);
+
+  if (queue)
+    {
+      GList *l;
+
+      memsize = sizeof (GQueue);
+
+      for (l = queue->head; l; l = g_list_next (l))
+        memsize += sizeof (GList) + func (l->data, gui_size);
+    }
+
+  return memsize;
+}
+
+gint64
+gimp_g_value_get_memsize (GValue *value)
+{
+  gint64 memsize = 0;
+
+  if (! value)
+    return 0;
+
+  if (G_VALUE_HOLDS_STRING (value))
+    {
+      memsize += gimp_string_get_memsize (g_value_get_string (value));
+    }
+  else if (G_VALUE_HOLDS_BOXED (value))
+    {
+      if (GIMP_VALUE_HOLDS_RGB (value))
+        {
+          memsize += sizeof (GimpRGB);
+        }
+      else if (GIMP_VALUE_HOLDS_MATRIX2 (value))
+        {
+          memsize += sizeof (GimpMatrix2);
+        }
+      else if (GIMP_VALUE_HOLDS_PARASITE (value))
+        {
+          memsize += gimp_parasite_get_memsize (g_value_get_boxed (value),
+                                                NULL);
+        }
+      else if (GIMP_VALUE_HOLDS_ARRAY (value)       ||
+               GIMP_VALUE_HOLDS_INT8_ARRAY (value)  ||
+               GIMP_VALUE_HOLDS_INT16_ARRAY (value) ||
+               GIMP_VALUE_HOLDS_INT32_ARRAY (value) ||
+               GIMP_VALUE_HOLDS_FLOAT_ARRAY (value))
+        {
+          GimpArray *array = g_value_get_boxed (value);
+
+          if (array)
+            memsize += sizeof (GimpArray) +
+                       (array->static_data ? 0 : array->length);
+        }
+      else if (GIMP_VALUE_HOLDS_STRING_ARRAY (value))
+        {
+          GimpArray *array = g_value_get_boxed (value);
+
+          if (array)
+            {
+              memsize += sizeof (GimpArray);
+
+              if (! array->static_data)
+                {
+                  gchar **tmp = (gchar **) array->data;
+                  gint    i;
+
+                  memsize += array->length * sizeof (gchar *);
+
+                  for (i = 0; i < array->length; i++)
+                    memsize += gimp_string_get_memsize (tmp[i]);
+                }
+            }
+        }
+      else
+        {
+          g_printerr ("%s: unhandled boxed value type: %s\n",
+                      G_STRFUNC, G_VALUE_TYPE_NAME (value));
+        }
+    }
+  else if (G_VALUE_HOLDS_OBJECT (value))
+    {
+      g_printerr ("%s: unhandled object value type: %s\n",
+                  G_STRFUNC, G_VALUE_TYPE_NAME (value));
+    }
+
+  return memsize + sizeof (GValue);
+}
+
+gint64
+gimp_g_param_spec_get_memsize (GParamSpec *pspec)
+{
+  gint64 memsize = 0;
+
+  if (! pspec)
+    return 0;
+
+  if (! (pspec->flags & G_PARAM_STATIC_NAME))
+    memsize += gimp_string_get_memsize (g_param_spec_get_name (pspec));
+
+  if (! (pspec->flags & G_PARAM_STATIC_NICK))
+    memsize += gimp_string_get_memsize (g_param_spec_get_nick (pspec));
+
+  if (! (pspec->flags & G_PARAM_STATIC_BLURB))
+    memsize += gimp_string_get_memsize (g_param_spec_get_blurb (pspec));
+
+  return memsize + gimp_g_type_instance_get_memsize ((GTypeInstance *) pspec);
+}
+
+gint64
+gimp_gegl_buffer_get_memsize (GeglBuffer *buffer)
+{
+  if (buffer)
+    {
+      const Babl *format = gegl_buffer_get_format (buffer);
+
+      return ((gint64) babl_format_get_bytes_per_pixel (format) *
+              (gint64) gegl_buffer_get_width (buffer) *
+              (gint64) gegl_buffer_get_height (buffer) +
+              gimp_g_object_get_memsize (G_OBJECT (buffer)));
+    }
+
+  return 0;
+}
+
+gint64
+gimp_gegl_pyramid_get_memsize (GeglBuffer *buffer)
+{
+  if (buffer)
+    {
+      const Babl *format = gegl_buffer_get_format (buffer);
+
+      /* The pyramid levels constitute a geometric sum with a ratio of 1/4. */
+      return ((gint64) babl_format_get_bytes_per_pixel (format) *
+              (gint64) gegl_buffer_get_width (buffer) *
+              (gint64) gegl_buffer_get_height (buffer) * 1.33 +
+              gimp_g_object_get_memsize (G_OBJECT (buffer)));
+    }
+
+  return 0;
+}
+
+gint64
+gimp_string_get_memsize (const gchar *string)
+{
+  if (string)
+    return strlen (string) + 1;
+
+  return 0;
+}
+
+gint64
+gimp_parasite_get_memsize (GimpParasite *parasite,
+                           gint64       *gui_size)
+{
+  if (parasite)
+    return (sizeof (GimpParasite) +
+            gimp_string_get_memsize (parasite->name) +
+            parasite->size);
+
+  return 0;
+}
diff --git a/app/core/gimp-memsize.h b/app/core/gimp-memsize.h
new file mode 100644
index 0000000..139dc02
--- /dev/null
+++ b/app/core/gimp-memsize.h
@@ -0,0 +1,60 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __APP_GIMP_MEMSIZE_H__
+#define __APP_GIMP_MEMSIZE_H__
+
+
+gint64   gimp_g_type_instance_get_memsize      (GTypeInstance   *instance);
+gint64   gimp_g_object_get_memsize             (GObject         *object);
+
+gint64   gimp_g_hash_table_get_memsize         (GHashTable      *hash,
+                                                gint64           data_size);
+gint64   gimp_g_hash_table_get_memsize_foreach (GHashTable      *hash,
+                                                GimpMemsizeFunc  func,
+                                                gint64          *gui_size);
+
+gint64   gimp_g_slist_get_memsize              (GSList          *slist,
+                                                gint64           data_size);
+gint64   gimp_g_slist_get_memsize_foreach      (GSList          *slist,
+                                                GimpMemsizeFunc  func,
+                                                gint64          *gui_size);
+
+gint64   gimp_g_list_get_memsize               (GList           *list,
+                                                gint64           data_size);
+gint64   gimp_g_list_get_memsize_foreach       (GList           *list,
+                                                GimpMemsizeFunc  func,
+                                                gint64          *gui_size);
+
+gint64   gimp_g_queue_get_memsize              (GQueue          *queue,
+                                                gint64           data_size);
+gint64   gimp_g_queue_get_memsize_foreach      (GQueue          *queue,
+                                                GimpMemsizeFunc  func,
+                                                gint64          *gui_size);
+
+gint64   gimp_g_value_get_memsize              (GValue          *value);
+gint64   gimp_g_param_spec_get_memsize         (GParamSpec      *pspec);
+
+gint64   gimp_gegl_buffer_get_memsize          (GeglBuffer      *buffer);
+gint64   gimp_gegl_pyramid_get_memsize         (GeglBuffer      *buffer);
+
+gint64   gimp_string_get_memsize               (const gchar     *string);
+gint64   gimp_parasite_get_memsize             (GimpParasite    *parasite,
+                                                gint64          *gui_size);
+
+
+#endif /* __APP_GIMP_MEMSIZE_H__ */
diff --git a/app/core/gimp-modules.c b/app/core/gimp-modules.c
new file mode 100644
index 0000000..6a7b30d
--- /dev/null
+++ b/app/core/gimp-modules.c
@@ -0,0 +1,227 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpmodules.c
+ * (C) 1999 Austin Donnelly <austin@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gio/gio.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpmodule/gimpmodule.h"
+#include "libgimpconfig/gimpconfig.h"
+
+#include "core-types.h"
+
+#include "config/gimpcoreconfig.h"
+
+#include "gimp.h"
+#include "gimp-modules.h"
+
+#include "gimp-intl.h"
+
+
+void
+gimp_modules_init (Gimp *gimp)
+{
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+
+  if (! gimp->no_interface)
+    {
+      gimp->module_db = gimp_module_db_new (gimp->be_verbose);
+      gimp->write_modulerc = FALSE;
+    }
+}
+
+void
+gimp_modules_exit (Gimp *gimp)
+{
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+
+  g_clear_object (&gimp->module_db);
+}
+
+void
+gimp_modules_load (Gimp *gimp)
+{
+  GFile    *file;
+  GScanner *scanner;
+  gchar    *module_load_inhibit = NULL;
+
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+
+  if (gimp->no_interface)
+    return;
+
+  /* FIXME, gimp->be_verbose is not yet initialized in init() */
+  gimp->module_db->verbose = gimp->be_verbose;
+
+  file = gimp_directory_file ("modulerc", NULL);
+
+  if (gimp->be_verbose)
+    g_print ("Parsing '%s'\n", gimp_file_get_utf8_name (file));
+
+  scanner = gimp_scanner_new_gfile (file, NULL);
+  g_object_unref (file);
+
+  if (scanner)
+    {
+      GTokenType  token;
+      GError     *error = NULL;
+
+#define MODULE_LOAD_INHIBIT 1
+
+      g_scanner_scope_add_symbol (scanner, 0, "module-load-inhibit",
+                                  GINT_TO_POINTER (MODULE_LOAD_INHIBIT));
+
+      token = G_TOKEN_LEFT_PAREN;
+
+      while (g_scanner_peek_next_token (scanner) == token)
+        {
+          token = g_scanner_get_next_token (scanner);
+
+          switch (token)
+            {
+            case G_TOKEN_LEFT_PAREN:
+              token = G_TOKEN_SYMBOL;
+              break;
+
+            case G_TOKEN_SYMBOL:
+              if (scanner->value.v_symbol == GINT_TO_POINTER (MODULE_LOAD_INHIBIT))
+                {
+                  token = G_TOKEN_STRING;
+
+                  if (! gimp_scanner_parse_string_no_validate (scanner,
+                                                               &module_load_inhibit))
+                    goto error;
+                }
+              token = G_TOKEN_RIGHT_PAREN;
+              break;
+
+            case G_TOKEN_RIGHT_PAREN:
+              token = G_TOKEN_LEFT_PAREN;
+              break;
+
+            default: /* do nothing */
+              break;
+            }
+        }
+
+#undef MODULE_LOAD_INHIBIT
+
+      if (token != G_TOKEN_LEFT_PAREN)
+        {
+          g_scanner_get_next_token (scanner);
+          g_scanner_unexp_token (scanner, token, NULL, NULL, NULL,
+                                 _("fatal parse error"), TRUE);
+        }
+
+    error:
+
+      if (error)
+        {
+          gimp_message_literal (gimp, NULL, GIMP_MESSAGE_ERROR, error->message);
+          g_clear_error (&error);
+        }
+
+      gimp_scanner_destroy (scanner);
+    }
+
+  if (module_load_inhibit)
+    {
+      gimp_module_db_set_load_inhibit (gimp->module_db, module_load_inhibit);
+      g_free (module_load_inhibit);
+    }
+
+  gimp_module_db_load (gimp->module_db, gimp->config->module_path);
+}
+
+static void
+add_to_inhibit_string (gpointer data,
+                       gpointer user_data)
+{
+  GimpModule *module = data;
+  GString    *str    = user_data;
+
+  if (module->load_inhibit)
+    {
+      g_string_append_c (str, G_SEARCHPATH_SEPARATOR);
+      g_string_append (str, module->filename);
+    }
+}
+
+void
+gimp_modules_unload (Gimp *gimp)
+{
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+
+  if (! gimp->no_interface && gimp->write_modulerc)
+    {
+      GimpConfigWriter *writer;
+      GString          *str;
+      const gchar      *p;
+      GFile            *file;
+      GError           *error = NULL;
+
+      str = g_string_new (NULL);
+      g_list_foreach (gimp->module_db->modules, add_to_inhibit_string, str);
+      if (str->len > 0)
+        p = str->str + 1;
+      else
+        p = "";
+
+      file = gimp_directory_file ("modulerc", NULL);
+
+      if (gimp->be_verbose)
+        g_print ("Writing '%s'\n", gimp_file_get_utf8_name (file));
+
+      writer = gimp_config_writer_new_gfile (file, TRUE,
+                                             "GIMP modulerc", &error);
+      g_object_unref (file);
+
+      if (writer)
+        {
+          gimp_config_writer_open (writer, "module-load-inhibit");
+          gimp_config_writer_string (writer, p);
+          gimp_config_writer_close (writer);
+
+          gimp_config_writer_finish (writer, "end of modulerc", &error);
+
+          gimp->write_modulerc = FALSE;
+        }
+
+      g_string_free (str, TRUE);
+
+      if (error)
+        {
+          gimp_message_literal (gimp, NULL, GIMP_MESSAGE_ERROR, error->message);
+          g_clear_error (&error);
+        }
+    }
+}
+
+void
+gimp_modules_refresh (Gimp *gimp)
+{
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+
+  if (! gimp->no_interface)
+    {
+      gimp_module_db_refresh (gimp->module_db, gimp->config->module_path);
+    }
+}
diff --git a/app/core/gimp-modules.h b/app/core/gimp-modules.h
new file mode 100644
index 0000000..fc90d69
--- /dev/null
+++ b/app/core/gimp-modules.h
@@ -0,0 +1,34 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpmodules.h
+ * (C) 1999 Austin Donnelly <austin@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_MODULES_H__
+#define __GIMP_MODULES_H__
+
+
+void   gimp_modules_init    (Gimp *gimp);
+void   gimp_modules_exit    (Gimp *gimp);
+
+void   gimp_modules_load    (Gimp *gimp);
+void   gimp_modules_unload  (Gimp *gimp);
+
+void   gimp_modules_refresh (Gimp *gimp);
+
+
+#endif  /* __GIMP_MODULES_H__ */
diff --git a/app/core/gimp-palettes.c b/app/core/gimp-palettes.c
new file mode 100644
index 0000000..4f189a4
--- /dev/null
+++ b/app/core/gimp-palettes.c
@@ -0,0 +1,143 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-2002 Spencer Kimball, Peter Mattis, and others
+ *
+ * gimp-gradients.c
+ * Copyright (C) 2014 Michael Natterer  <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+
+#include "core-types.h"
+
+#include "gimp.h"
+#include "gimp-palettes.h"
+#include "gimpcontext.h"
+#include "gimpcontainer.h"
+#include "gimpdatafactory.h"
+#include "gimppalettemru.h"
+
+#include "gimp-intl.h"
+
+
+#define COLOR_HISTORY_KEY "gimp-palette-color-history"
+
+
+/*  local function prototypes  */
+
+static GimpPalette * gimp_palettes_add_palette (Gimp        *gimp,
+                                                const gchar *name,
+                                                const gchar *id);
+
+
+/*  public functions  */
+
+void
+gimp_palettes_init (Gimp *gimp)
+{
+  GimpPalette *palette;
+
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+
+  palette = gimp_palettes_add_palette (gimp,
+                                       _("Color History"),
+                                       COLOR_HISTORY_KEY);
+  gimp_context_set_palette (gimp->user_context, palette);
+}
+
+void
+gimp_palettes_load (Gimp *gimp)
+{
+  GimpPalette *palette;
+  GFile       *file;
+
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+
+  palette = gimp_palettes_get_color_history (gimp);
+
+  file = gimp_directory_file ("colorrc", NULL);
+
+  if (gimp->be_verbose)
+    g_print ("Parsing '%s'\n", gimp_file_get_utf8_name (file));
+
+  gimp_palette_mru_load (GIMP_PALETTE_MRU (palette), file);
+
+  g_object_unref (file);
+}
+
+void
+gimp_palettes_save (Gimp *gimp)
+{
+  GimpPalette *palette;
+  GFile       *file;
+
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+
+  palette = gimp_palettes_get_color_history (gimp);
+
+  file = gimp_directory_file ("colorrc", NULL);
+
+  if (gimp->be_verbose)
+    g_print ("Writing '%s'\n", gimp_file_get_utf8_name (file));
+
+  gimp_palette_mru_save (GIMP_PALETTE_MRU (palette), file);
+
+  g_object_unref (file);
+}
+
+GimpPalette *
+gimp_palettes_get_color_history (Gimp *gimp)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  return g_object_get_data (G_OBJECT (gimp), COLOR_HISTORY_KEY);
+}
+
+void
+gimp_palettes_add_color_history (Gimp          *gimp,
+                                 const GimpRGB *color)
+{
+  GimpPalette *history;
+
+  history = gimp_palettes_get_color_history (gimp);
+  gimp_palette_mru_add (GIMP_PALETTE_MRU (history), color);
+}
+
+/*  private functions  */
+
+static GimpPalette *
+gimp_palettes_add_palette (Gimp        *gimp,
+                           const gchar *name,
+                           const gchar *id)
+{
+  GimpData *palette;
+
+  palette = gimp_palette_mru_new (name);
+
+  gimp_data_make_internal (palette, id);
+
+  gimp_container_add (gimp_data_factory_get_container (gimp->palette_factory),
+                      GIMP_OBJECT (palette));
+  g_object_unref (palette);
+
+  g_object_set_data (G_OBJECT (gimp), id, palette);
+
+  return GIMP_PALETTE (palette);
+}
diff --git a/app/core/gimp-palettes.h b/app/core/gimp-palettes.h
new file mode 100644
index 0000000..7858c86
--- /dev/null
+++ b/app/core/gimp-palettes.h
@@ -0,0 +1,35 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-2002 Spencer Kimball, Peter Mattis, and others
+ *
+ * gimp-palettes.h
+ * Copyright (C) 2014 Michael Natterer  <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_PALETTES__
+#define __GIMP_PALETTES__
+
+
+void          gimp_palettes_init              (Gimp          *gimp);
+
+void          gimp_palettes_load              (Gimp          *gimp);
+void          gimp_palettes_save              (Gimp          *gimp);
+
+GimpPalette * gimp_palettes_get_color_history (Gimp          *gimp);
+void          gimp_palettes_add_color_history (Gimp          *gimp,
+                                               const GimpRGB *color);
+
+
+#endif /* __GIMP_PALETTES__ */
diff --git a/app/core/gimp-parallel.cc b/app/core/gimp-parallel.cc
new file mode 100644
index 0000000..208bcfe
--- /dev/null
+++ b/app/core/gimp-parallel.cc
@@ -0,0 +1,553 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimp-parallel.c
+ * Copyright (C) 2018 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+
+#include "config.h"
+
+#include <gio/gio.h>
+#include <gegl.h>
+
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+
+#ifdef G_OS_WIN32
+#include <windows.h>
+#endif
+
+extern "C"
+{
+
+#include "core-types.h"
+
+#include "config/gimpgeglconfig.h"
+
+#include "gimp.h"
+#include "gimp-parallel.h"
+#include "gimpasync.h"
+#include "gimpcancelable.h"
+
+
+#define GIMP_PARALLEL_MAX_THREADS           64
+#define GIMP_PARALLEL_RUN_ASYNC_MAX_THREADS  1
+
+
+typedef struct
+{
+  GimpAsync        *async;
+  gint              priority;
+  GimpRunAsyncFunc  func;
+  gpointer          user_data;
+  GDestroyNotify    user_data_destroy_func;
+} GimpParallelRunAsyncTask;
+
+typedef struct
+{
+  GThread   *thread;
+
+  gboolean   quit;
+
+  GimpAsync *current_async;
+} GimpParallelRunAsyncThread;
+
+
+/*  local function prototypes  */
+
+static void                       gimp_parallel_notify_num_processors   (GimpGeglConfig             *config);
+
+static void                       gimp_parallel_set_n_threads           (gint                        n_threads,
+                                                                         gboolean                    finish_tasks);
+
+static void                       gimp_parallel_run_async_set_n_threads (gint                        n_threads,
+                                                                         gboolean                    finish_tasks);
+static gpointer                   gimp_parallel_run_async_thread_func   (GimpParallelRunAsyncThread *thread);
+static void                       gimp_parallel_run_async_enqueue_task  (GimpParallelRunAsyncTask   *task);
+static GimpParallelRunAsyncTask * gimp_parallel_run_async_dequeue_task  (void);
+static gboolean                   gimp_parallel_run_async_execute_task  (GimpParallelRunAsyncTask   *task);
+static void                       gimp_parallel_run_async_abort_task    (GimpParallelRunAsyncTask   *task);
+static void                       gimp_parallel_run_async_cancel        (GimpAsync                  *async);
+static void                       gimp_parallel_run_async_waiting       (GimpAsync                  *async);
+
+
+/*  local variables  */
+
+static gint                       gimp_parallel_run_async_n_threads = 0;
+static GimpParallelRunAsyncThread gimp_parallel_run_async_threads[GIMP_PARALLEL_RUN_ASYNC_MAX_THREADS];
+
+static GMutex                     gimp_parallel_run_async_mutex;
+static GCond                      gimp_parallel_run_async_cond;
+static GQueue                     gimp_parallel_run_async_queue = G_QUEUE_INIT;
+
+
+/*  public functions  */
+
+
+void
+gimp_parallel_init (Gimp *gimp)
+{
+  GimpGeglConfig *config;
+
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+
+  config = GIMP_GEGL_CONFIG (gimp->config);
+
+  g_signal_connect (config, "notify::num-processors",
+                    G_CALLBACK (gimp_parallel_notify_num_processors),
+                    NULL);
+
+  gimp_parallel_notify_num_processors (config);
+}
+
+void
+gimp_parallel_exit (Gimp *gimp)
+{
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+
+  g_signal_handlers_disconnect_by_func (gimp->config,
+                                        (gpointer) gimp_parallel_notify_num_processors,
+                                        NULL);
+
+  /* stop all threads */
+  gimp_parallel_set_n_threads (0, /* finish_tasks = */ FALSE);
+}
+
+GimpAsync *
+gimp_parallel_run_async (GimpRunAsyncFunc func,
+                         gpointer         user_data)
+{
+  return gimp_parallel_run_async_full (0, func, user_data, NULL);
+}
+
+GimpAsync *
+gimp_parallel_run_async_full (gint             priority,
+                              GimpRunAsyncFunc func,
+                              gpointer         user_data,
+                              GDestroyNotify   user_data_destroy_func)
+{
+  GimpAsync                *async;
+  GimpParallelRunAsyncTask *task;
+
+  g_return_val_if_fail (func != NULL, NULL);
+
+  async = gimp_async_new ();
+
+  task = g_slice_new (GimpParallelRunAsyncTask);
+
+  task->async                  = GIMP_ASYNC (g_object_ref (async));
+  task->priority               = priority;
+  task->func                   = func;
+  task->user_data              = user_data;
+  task->user_data_destroy_func = user_data_destroy_func;
+
+  if (gimp_parallel_run_async_n_threads > 0)
+    {
+      g_signal_connect_after (async, "cancel",
+                              G_CALLBACK (gimp_parallel_run_async_cancel),
+                              NULL);
+      g_signal_connect_after (async, "waiting",
+                              G_CALLBACK (gimp_parallel_run_async_waiting),
+                              NULL);
+
+      g_mutex_lock (&gimp_parallel_run_async_mutex);
+
+      gimp_parallel_run_async_enqueue_task (task);
+
+      g_cond_signal (&gimp_parallel_run_async_cond);
+
+      g_mutex_unlock (&gimp_parallel_run_async_mutex);
+    }
+  else
+    {
+      while (gimp_parallel_run_async_execute_task (task));
+    }
+
+  return async;
+}
+
+GimpAsync *
+gimp_parallel_run_async_independent (GimpRunAsyncFunc func,
+                                     gpointer         user_data)
+{
+  return gimp_parallel_run_async_independent_full (0, func, user_data);
+}
+
+GimpAsync *
+gimp_parallel_run_async_independent_full (gint             priority,
+                                          GimpRunAsyncFunc func,
+                                          gpointer         user_data)
+{
+  GimpAsync                *async;
+  GimpParallelRunAsyncTask *task;
+  GThread                  *thread;
+
+  g_return_val_if_fail (func != NULL, NULL);
+
+  async = gimp_async_new ();
+
+  task = g_slice_new0 (GimpParallelRunAsyncTask);
+
+  task->async     = GIMP_ASYNC (g_object_ref (async));
+  task->priority  = priority;
+  task->func      = func;
+  task->user_data = user_data;
+
+  thread = g_thread_new (
+    "async-ind",
+    [] (gpointer data) -> gpointer
+    {
+      GimpParallelRunAsyncTask *task = (GimpParallelRunAsyncTask *) data;
+
+      /* adjust the thread's priority */
+#if defined (G_OS_WIN32)
+      if (task->priority < 0)
+        {
+          SetThreadPriority (GetCurrentThread (), THREAD_PRIORITY_ABOVE_NORMAL);
+        }
+      else if (task->priority > 0)
+        {
+          SetThreadPriority (GetCurrentThread (), THREAD_MODE_BACKGROUND_BEGIN);
+        }
+#elif defined (HAVE_UNISTD_H) && defined (__gnu_linux__)
+      if (task->priority)
+        {
+          (nice (task->priority) != -1);
+                              /* ^-- avoid "unused result" warning */
+        }
+#endif
+
+      while (gimp_parallel_run_async_execute_task (task));
+
+      return NULL;
+    },
+    task);
+
+  gimp_async_add_callback (async,
+                           [] (GimpAsync *async,
+                               gpointer   thread)
+                           {
+                             g_thread_join ((GThread *) thread);
+                           },
+                           thread);
+
+  return async;
+}
+
+
+/*  private functions  */
+
+
+static void
+gimp_parallel_notify_num_processors (GimpGeglConfig *config)
+{
+  gimp_parallel_set_n_threads (config->num_processors,
+                               /* finish_tasks = */ TRUE);
+}
+
+static void
+gimp_parallel_set_n_threads (gint     n_threads,
+                             gboolean finish_tasks)
+{
+  gimp_parallel_run_async_set_n_threads (n_threads, finish_tasks);
+}
+
+static void
+gimp_parallel_run_async_set_n_threads (gint     n_threads,
+                                       gboolean finish_tasks)
+{
+  gint i;
+
+  n_threads = CLAMP (n_threads, 0, GIMP_PARALLEL_RUN_ASYNC_MAX_THREADS);
+
+  if (n_threads > gimp_parallel_run_async_n_threads) /* need more threads */
+    {
+      for (i = gimp_parallel_run_async_n_threads; i < n_threads; i++)
+        {
+          GimpParallelRunAsyncThread *thread =
+            &gimp_parallel_run_async_threads[i];
+
+          thread->quit = FALSE;
+
+          thread->thread = g_thread_new (
+            "async",
+            (GThreadFunc) gimp_parallel_run_async_thread_func,
+            thread);
+        }
+    }
+  else if (n_threads < gimp_parallel_run_async_n_threads) /* need less threads */
+    {
+      g_mutex_lock (&gimp_parallel_run_async_mutex);
+
+      for (i = n_threads; i < gimp_parallel_run_async_n_threads; i++)
+        {
+          GimpParallelRunAsyncThread *thread =
+            &gimp_parallel_run_async_threads[i];
+
+          thread->quit = TRUE;
+
+          if (thread->current_async && ! finish_tasks)
+            gimp_cancelable_cancel (GIMP_CANCELABLE (thread->current_async));
+        }
+
+      g_cond_broadcast (&gimp_parallel_run_async_cond);
+
+      g_mutex_unlock (&gimp_parallel_run_async_mutex);
+
+      for (i = n_threads; i < gimp_parallel_run_async_n_threads; i++)
+        {
+          GimpParallelRunAsyncThread *thread =
+            &gimp_parallel_run_async_threads[i];
+
+          g_thread_join (thread->thread);
+        }
+    }
+
+  gimp_parallel_run_async_n_threads = n_threads;
+
+  if (n_threads == 0)
+    {
+      GimpParallelRunAsyncTask *task;
+
+      /* finish remaining tasks */
+      while ((task = gimp_parallel_run_async_dequeue_task ()))
+        {
+          if (finish_tasks)
+            while (gimp_parallel_run_async_execute_task (task));
+          else
+            gimp_parallel_run_async_abort_task (task);
+        }
+    }
+}
+
+static gpointer
+gimp_parallel_run_async_thread_func (GimpParallelRunAsyncThread *thread)
+{
+  g_mutex_lock (&gimp_parallel_run_async_mutex);
+
+  while (TRUE)
+    {
+      GimpParallelRunAsyncTask *task;
+
+      while (! thread->quit &&
+             (task = gimp_parallel_run_async_dequeue_task ()))
+        {
+          gboolean resume;
+
+          thread->current_async = GIMP_ASYNC (g_object_ref (task->async));
+
+          do
+            {
+              g_mutex_unlock (&gimp_parallel_run_async_mutex);
+
+              resume = gimp_parallel_run_async_execute_task (task);
+
+              g_mutex_lock (&gimp_parallel_run_async_mutex);
+            }
+          while (resume &&
+                 (g_queue_is_empty (&gimp_parallel_run_async_queue) ||
+                  task->priority <
+                  ((GimpParallelRunAsyncTask *)
+                     g_queue_peek_head (
+                       &gimp_parallel_run_async_queue))->priority));
+
+          g_clear_object (&thread->current_async);
+
+          if (resume)
+            gimp_parallel_run_async_enqueue_task (task);
+        }
+
+      if (thread->quit)
+        break;
+
+      g_cond_wait (&gimp_parallel_run_async_cond,
+                   &gimp_parallel_run_async_mutex);
+    }
+
+  g_mutex_unlock (&gimp_parallel_run_async_mutex);
+
+  return NULL;
+}
+
+static void
+gimp_parallel_run_async_enqueue_task (GimpParallelRunAsyncTask *task)
+{
+  GList *link;
+  GList *iter;
+
+  if (gimp_async_is_canceled (task->async))
+    {
+      gimp_parallel_run_async_abort_task (task);
+
+      return;
+    }
+
+  link       = g_list_alloc ();
+  link->data = task;
+
+  g_object_set_data (G_OBJECT (task->async),
+                     "gimp-parallel-run-async-link", link);
+
+  for (iter = g_queue_peek_tail_link (&gimp_parallel_run_async_queue);
+       iter;
+       iter = g_list_previous (iter))
+    {
+      GimpParallelRunAsyncTask *other_task =
+        (GimpParallelRunAsyncTask *) iter->data;
+
+      if (other_task->priority <= task->priority)
+        break;
+    }
+
+  if (iter)
+    {
+      link->prev = iter;
+      link->next = iter->next;
+
+      iter->next = link;
+
+      if (link->next)
+        link->next->prev = link;
+      else
+        gimp_parallel_run_async_queue.tail = link;
+
+      gimp_parallel_run_async_queue.length++;
+    }
+  else
+    {
+      g_queue_push_head_link (&gimp_parallel_run_async_queue, link);
+    }
+}
+
+static GimpParallelRunAsyncTask *
+gimp_parallel_run_async_dequeue_task (void)
+{
+  GimpParallelRunAsyncTask *task;
+
+  task = (GimpParallelRunAsyncTask *) g_queue_pop_head (
+                                        &gimp_parallel_run_async_queue);
+
+  if (task)
+    {
+      g_object_set_data (G_OBJECT (task->async),
+                         "gimp-parallel-run-async-link", NULL);
+    }
+
+  return task;
+}
+
+static gboolean
+gimp_parallel_run_async_execute_task (GimpParallelRunAsyncTask *task)
+{
+  if (gimp_async_is_canceled (task->async))
+    {
+      gimp_parallel_run_async_abort_task (task);
+
+      return FALSE;
+    }
+
+  task->func (task->async, task->user_data);
+
+  if (gimp_async_is_stopped (task->async))
+    {
+      g_object_unref (task->async);
+
+      g_slice_free (GimpParallelRunAsyncTask, task);
+
+      return FALSE;
+    }
+
+  return TRUE;
+}
+
+static void
+gimp_parallel_run_async_abort_task (GimpParallelRunAsyncTask *task)
+{
+  if (task->user_data && task->user_data_destroy_func)
+    task->user_data_destroy_func (task->user_data);
+
+  gimp_async_abort (task->async);
+
+  g_object_unref (task->async);
+
+  g_slice_free (GimpParallelRunAsyncTask, task);
+}
+
+static void
+gimp_parallel_run_async_cancel (GimpAsync *async)
+{
+  GList                    *link;
+  GimpParallelRunAsyncTask *task = NULL;
+
+  link = (GList *) g_object_get_data (G_OBJECT (async),
+                                      "gimp-parallel-run-async-link");
+
+  if (! link)
+    return;
+
+  g_mutex_lock (&gimp_parallel_run_async_mutex);
+
+  link = (GList *) g_object_get_data (G_OBJECT (async),
+                                      "gimp-parallel-run-async-link");
+
+  if (link)
+    {
+      g_object_set_data (G_OBJECT (async),
+                         "gimp-parallel-run-async-link", NULL);
+
+      task = (GimpParallelRunAsyncTask *) link->data;
+
+      g_queue_delete_link (&gimp_parallel_run_async_queue, link);
+    }
+
+  g_mutex_unlock (&gimp_parallel_run_async_mutex);
+
+  if (task)
+    gimp_parallel_run_async_abort_task (task);
+}
+
+static void
+gimp_parallel_run_async_waiting (GimpAsync *async)
+{
+  GList *link;
+
+  link = (GList *) g_object_get_data (G_OBJECT (async),
+                                      "gimp-parallel-run-async-link");
+
+  if (! link)
+    return;
+
+  g_mutex_lock (&gimp_parallel_run_async_mutex);
+
+  link = (GList *) g_object_get_data (G_OBJECT (async),
+                                      "gimp-parallel-run-async-link");
+
+  if (link)
+    {
+      GimpParallelRunAsyncTask *task = (GimpParallelRunAsyncTask *) link->data;
+
+      task->priority = G_MININT;
+
+      g_queue_unlink         (&gimp_parallel_run_async_queue, link);
+      g_queue_push_head_link (&gimp_parallel_run_async_queue, link);
+    }
+
+  g_mutex_unlock (&gimp_parallel_run_async_mutex);
+}
+
+} /* extern "C" */
diff --git a/app/core/gimp-parallel.h b/app/core/gimp-parallel.h
new file mode 100644
index 0000000..76abc1d
--- /dev/null
+++ b/app/core/gimp-parallel.h
@@ -0,0 +1,157 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimp-parallel.h
+ * Copyright (C) 2018 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_PARALLEL_H__
+#define __GIMP_PARALLEL_H__
+
+
+void        gimp_parallel_init                       (Gimp             *gimp);
+void        gimp_parallel_exit                       (Gimp             *gimp);
+
+GimpAsync * gimp_parallel_run_async                  (GimpRunAsyncFunc  func,
+                                                      gpointer          user_data);
+GimpAsync * gimp_parallel_run_async_full             (gint              priority,
+                                                      GimpRunAsyncFunc  func,
+                                                      gpointer          user_data,
+                                                      GDestroyNotify    user_data_destroy_func);
+GimpAsync * gimp_parallel_run_async_independent      (GimpRunAsyncFunc  func,
+                                                      gpointer          user_data);
+GimpAsync * gimp_parallel_run_async_independent_full (gint              priority,
+                                                      GimpRunAsyncFunc  func,
+                                                      gpointer          user_data);
+
+
+#ifdef __cplusplus
+
+extern "C++"
+{
+
+#include <new>
+
+template <class RunAsyncFunc>
+inline GimpAsync *
+gimp_parallel_run_async (RunAsyncFunc func)
+{
+  RunAsyncFunc *func_copy = g_new (RunAsyncFunc, 1);
+
+  new (func_copy) RunAsyncFunc (func);
+
+  return gimp_parallel_run_async_full (0,
+                                       [] (GimpAsync *async,
+                                           gpointer   user_data)
+                                       {
+                                         RunAsyncFunc *func_copy =
+                                           (RunAsyncFunc *) user_data;
+
+                                         (*func_copy) (async);
+
+                                         func_copy->~RunAsyncFunc ();
+                                         g_free (func_copy);
+                                       },
+                                       func_copy,
+                                       [] (gpointer user_data)
+                                       {
+                                         RunAsyncFunc *func_copy =
+                                           (RunAsyncFunc *) user_data;
+
+                                         func_copy->~RunAsyncFunc ();
+                                         g_free (func_copy);
+                                       });
+}
+
+template <class RunAsyncFunc,
+          class DestroyFunc>
+inline GimpAsync *
+gimp_parallel_run_async_full (gint         priority,
+                              RunAsyncFunc func,
+                              DestroyFunc  destroy_func)
+{
+  typedef struct
+  {
+    RunAsyncFunc func;
+    DestroyFunc  destroy_func;
+  } Funcs;
+
+  Funcs *funcs_copy = g_new (Funcs, 1);
+
+  new (funcs_copy) Funcs {func, destroy_func};
+
+  return gimp_parallel_run_async_full (priority,
+                                       [] (GimpAsync *async,
+                                           gpointer   user_data)
+                                       {
+                                         Funcs *funcs_copy =
+                                           (Funcs *) user_data;
+
+                                         funcs_copy->func (async);
+
+                                         funcs_copy->~Funcs ();
+                                         g_free (funcs_copy);
+                                       },
+                                       funcs_copy,
+                                       [] (gpointer user_data)
+                                       {
+                                         Funcs *funcs_copy =
+                                           (Funcs *) user_data;
+
+                                         funcs_copy->destroy_func ();
+
+                                         funcs_copy->~Funcs ();
+                                         g_free (funcs_copy);
+                                       });
+}
+
+template <class RunAsyncFunc>
+inline GimpAsync *
+gimp_parallel_run_async_independent_full (gint         priority,
+                                          RunAsyncFunc func)
+{
+  RunAsyncFunc *func_copy = g_new (RunAsyncFunc, 1);
+
+  new (func_copy) RunAsyncFunc (func);
+
+  return gimp_parallel_run_async_independent_full (priority,
+                                                   [] (GimpAsync *async,
+                                                       gpointer   user_data)
+                                                   {
+                                                     RunAsyncFunc *func_copy =
+                                                       (RunAsyncFunc *) user_data;
+
+                                                     (*func_copy) (async);
+
+                                                     func_copy->~RunAsyncFunc ();
+                                                     g_free (func_copy);
+                                                   },
+                                                   func_copy);
+}
+
+template <class RunAsyncFunc>
+inline GimpAsync *
+gimp_parallel_run_async_independent (RunAsyncFunc func)
+{
+  return gimp_parallel_run_async_independent_full (0, func);
+}
+
+}
+
+#endif /* __cplusplus */
+
+
+#endif /* __GIMP_PARALLEL_H__ */
diff --git a/app/core/gimp-parasites.c b/app/core/gimp-parasites.c
new file mode 100644
index 0000000..e781a54
--- /dev/null
+++ b/app/core/gimp-parasites.c
@@ -0,0 +1,170 @@
+/* gimpparasite.c: Copyright 1998 Jay Cox <jaycox@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gio/gio.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpconfig/gimpconfig.h"
+
+#include "core-types.h"
+
+#include "gimp.h"
+#include "gimp-parasites.h"
+#include "gimpparasitelist.h"
+
+
+gboolean
+gimp_parasite_validate (Gimp                *gimp,
+                        const GimpParasite  *parasite,
+                        GError             **error)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), FALSE);
+  g_return_val_if_fail (parasite != NULL, FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  return TRUE;
+}
+
+void
+gimp_parasite_attach (Gimp               *gimp,
+                      const GimpParasite *parasite)
+{
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+  g_return_if_fail (parasite != NULL);
+
+  gimp_parasite_list_add (gimp->parasites, parasite);
+}
+
+void
+gimp_parasite_detach (Gimp        *gimp,
+                      const gchar *name)
+{
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+  g_return_if_fail (name != NULL);
+
+  gimp_parasite_list_remove (gimp->parasites, name);
+}
+
+const GimpParasite *
+gimp_parasite_find (Gimp        *gimp,
+                    const gchar *name)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+  g_return_val_if_fail (name != NULL, NULL);
+
+  return gimp_parasite_list_find (gimp->parasites, name);
+}
+
+static void
+list_func (const gchar    *key,
+           GimpParasite   *parasite,
+           gchar        ***current)
+{
+  *(*current)++ = g_strdup (key);
+}
+
+gchar **
+gimp_parasite_list (Gimp *gimp,
+                    gint *count)
+{
+  gchar **list;
+  gchar **current;
+
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+  g_return_val_if_fail (count != NULL, NULL);
+
+  *count = gimp_parasite_list_length (gimp->parasites);
+
+  list = current = g_new (gchar *, *count);
+
+  gimp_parasite_list_foreach (gimp->parasites, (GHFunc) list_func, &current);
+
+  return list;
+}
+
+
+/*  FIXME: this doesn't belong here  */
+
+void
+gimp_parasite_shift_parent (GimpParasite *parasite)
+{
+  g_return_if_fail (parasite != NULL);
+
+  parasite->flags = (parasite->flags >> 8);
+}
+
+
+/*  parasiterc functions  */
+
+void
+gimp_parasiterc_load (Gimp *gimp)
+{
+  GFile  *file;
+  GError *error = NULL;
+
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+
+  file = gimp_directory_file ("parasiterc", NULL);
+
+  if (gimp->be_verbose)
+    g_print ("Parsing '%s'\n", gimp_file_get_utf8_name (file));
+
+  if (! gimp_config_deserialize_gfile (GIMP_CONFIG (gimp->parasites),
+                                       file, NULL, &error))
+    {
+      if (error->code != GIMP_CONFIG_ERROR_OPEN_ENOENT)
+        gimp_message_literal (gimp, NULL, GIMP_MESSAGE_ERROR, error->message);
+
+      g_error_free (error);
+    }
+
+  g_object_unref (file);
+}
+
+void
+gimp_parasiterc_save (Gimp *gimp)
+{
+  const gchar *header =
+    "GIMP parasiterc\n"
+    "\n"
+    "This file will be entirely rewritten each time you exit.";
+  const gchar *footer =
+    "end of parasiterc";
+
+  GFile  *file;
+  GError *error = NULL;
+
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+  g_return_if_fail (GIMP_IS_PARASITE_LIST (gimp->parasites));
+
+  file = gimp_directory_file ("parasiterc", NULL);
+
+  if (gimp->be_verbose)
+    g_print ("Writing '%s'\n", gimp_file_get_utf8_name (file));
+
+  if (! gimp_config_serialize_to_gfile (GIMP_CONFIG (gimp->parasites),
+                                        file,
+                                        header, footer, NULL,
+                                        &error))
+    {
+      gimp_message_literal (gimp, NULL, GIMP_MESSAGE_ERROR, error->message);
+      g_error_free (error);
+    }
+
+  g_object_unref (file);
+}
diff --git a/app/core/gimp-parasites.h b/app/core/gimp-parasites.h
new file mode 100644
index 0000000..06d38c8
--- /dev/null
+++ b/app/core/gimp-parasites.h
@@ -0,0 +1,41 @@
+/* gimpparasite.h: Copyright 1998 Jay Cox <jaycox@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_PARASITES_H__
+#define __GIMP_PARASITES_H__
+
+
+/* some wrappers to access gimp->parasites, mainly for the PDB */
+
+gboolean              gimp_parasite_validate     (Gimp               *gimp,
+                                                  const GimpParasite *parasite,
+                                                  GError            **error);
+void                  gimp_parasite_attach       (Gimp               *gimp,
+                                                  const GimpParasite *parasite);
+void                  gimp_parasite_detach       (Gimp               *gimp,
+                                                  const gchar        *name);
+const GimpParasite  * gimp_parasite_find         (Gimp               *gimp,
+                                                  const gchar        *name);
+gchar              ** gimp_parasite_list         (Gimp               *gimp,
+                                                  gint               *count);
+
+void                  gimp_parasite_shift_parent (GimpParasite       *parasite);
+
+void                  gimp_parasiterc_load       (Gimp               *gimp);
+void                  gimp_parasiterc_save       (Gimp               *gimp);
+
+
+#endif  /*  __GIMP_PARASITES_H__  */
diff --git a/app/core/gimp-spawn.c b/app/core/gimp-spawn.c
new file mode 100644
index 0000000..bfa08e8
--- /dev/null
+++ b/app/core/gimp-spawn.c
@@ -0,0 +1,250 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimp-spawn.c
+ * Copyright (C) 2018 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <glib-object.h>
+
+#ifdef HAVE_VFORK
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#include <errno.h>
+#endif
+
+#ifdef HAVE_FCNTL_H
+#include <fcntl.h>
+#endif
+
+#ifdef G_OS_WIN32
+#include <windows.h>
+#include <io.h>
+#endif
+
+#include "core-types.h"
+
+#include "gimp-spawn.h"
+
+#include "gimp-intl.h"
+
+
+#ifdef HAVE_VFORK
+
+/* copied from glib */
+static gint
+exec_err_to_g_error (gint en)
+{
+  switch (en)
+    {
+#ifdef EACCES
+    case EACCES:
+      return G_SPAWN_ERROR_ACCES;
+      break;
+#endif
+
+#ifdef EPERM
+    case EPERM:
+      return G_SPAWN_ERROR_PERM;
+      break;
+#endif
+
+#ifdef E2BIG
+    case E2BIG:
+      return G_SPAWN_ERROR_TOO_BIG;
+      break;
+#endif
+
+#ifdef ENOEXEC
+    case ENOEXEC:
+      return G_SPAWN_ERROR_NOEXEC;
+      break;
+#endif
+
+#ifdef ENAMETOOLONG
+    case ENAMETOOLONG:
+      return G_SPAWN_ERROR_NAMETOOLONG;
+      break;
+#endif
+
+#ifdef ENOENT
+    case ENOENT:
+      return G_SPAWN_ERROR_NOENT;
+      break;
+#endif
+
+#ifdef ENOMEM
+    case ENOMEM:
+      return G_SPAWN_ERROR_NOMEM;
+      break;
+#endif
+
+#ifdef ENOTDIR
+    case ENOTDIR:
+      return G_SPAWN_ERROR_NOTDIR;
+      break;
+#endif
+
+#ifdef ELOOP
+    case ELOOP:
+      return G_SPAWN_ERROR_LOOP;
+      break;
+#endif
+
+#ifdef ETXTBUSY
+    case ETXTBUSY:
+      return G_SPAWN_ERROR_TXTBUSY;
+      break;
+#endif
+
+#ifdef EIO
+    case EIO:
+      return G_SPAWN_ERROR_IO;
+      break;
+#endif
+
+#ifdef ENFILE
+    case ENFILE:
+      return G_SPAWN_ERROR_NFILE;
+      break;
+#endif
+
+#ifdef EMFILE
+    case EMFILE:
+      return G_SPAWN_ERROR_MFILE;
+      break;
+#endif
+
+#ifdef EINVAL
+    case EINVAL:
+      return G_SPAWN_ERROR_INVAL;
+      break;
+#endif
+
+#ifdef EISDIR
+    case EISDIR:
+      return G_SPAWN_ERROR_ISDIR;
+      break;
+#endif
+
+#ifdef ELIBBAD
+    case ELIBBAD:
+      return G_SPAWN_ERROR_LIBBAD;
+      break;
+#endif
+
+    default:
+      return G_SPAWN_ERROR_FAILED;
+      break;
+    }
+}
+
+#endif /* HAVE_VFORK */
+
+gboolean
+gimp_spawn_async (gchar       **argv,
+                  gchar       **envp,
+                  GSpawnFlags   flags,
+                  GPid         *child_pid,
+                  GError      **error)
+{
+  g_return_val_if_fail (argv != NULL, FALSE);
+  g_return_val_if_fail (argv[0] != NULL, FALSE);
+
+#ifdef HAVE_VFORK
+  if (flags == (G_SPAWN_LEAVE_DESCRIPTORS_OPEN |
+                G_SPAWN_DO_NOT_REAP_CHILD      |
+                G_SPAWN_CHILD_INHERITS_STDIN))
+    {
+      pid_t pid;
+
+      pid = vfork ();
+
+      if (pid < 0)
+        {
+          gint errsv = errno;
+
+          g_set_error (error,
+                       G_SPAWN_ERROR,
+                       G_SPAWN_ERROR_FORK,
+                       _("Failed to fork (%s)"),
+                       g_strerror (errsv));
+
+          return FALSE;
+        }
+      else if (pid == 0)
+        {
+          if (envp)
+            execve (argv[0], argv, envp);
+          else
+            execv (argv[0], argv);
+
+          _exit (errno);
+        }
+      else
+        {
+          int   status = -1;
+          pid_t result;
+
+          result = waitpid (pid, &status, WNOHANG);
+
+          if (result)
+            {
+              if (result < 0)
+                {
+                  g_warning ("waitpid() should not fail in "
+                             "gimp_spawn_async()");
+                }
+
+              if (WIFEXITED (status))
+                status = WEXITSTATUS (status);
+              else
+                status = -1;
+
+              g_set_error (error,
+                           G_SPAWN_ERROR,
+                           exec_err_to_g_error (status),
+                           _("Failed to execute child process “%s” (%s)"),
+                           argv[0],
+                           g_strerror (status));
+
+              return FALSE;
+            }
+
+          if (child_pid) *child_pid = pid;
+
+          return TRUE;
+        }
+    }
+#endif /* HAVE_VFORK */
+
+  return g_spawn_async (NULL, argv, envp, flags, NULL, NULL, child_pid, error);
+}
+
+void
+gimp_spawn_set_cloexec (gint fd)
+{
+#if defined (G_OS_WIN32)
+  SetHandleInformation ((HANDLE) _get_osfhandle (fd), HANDLE_FLAG_INHERIT, 0);
+#elif defined (HAVE_FCNTL_H)
+  fcntl (fd, F_SETFD, fcntl (fd, F_GETFD, 0) | FD_CLOEXEC);
+#elif defined (__GNUC__)
+#warning gimp_spawn_set_cloexec() is not implemented for the target platform
+#endif
+}
diff --git a/app/core/gimp-spawn.h b/app/core/gimp-spawn.h
new file mode 100644
index 0000000..f81cf7d
--- /dev/null
+++ b/app/core/gimp-spawn.h
@@ -0,0 +1,34 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimp-spawn.h
+ * Copyright (C) 2018 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_SPAWN_H__
+#define __GIMP_SPAWN_H__
+
+
+gboolean   gimp_spawn_async       (gchar       **argv,
+                                   gchar       **envp,
+                                   GSpawnFlags   flags,
+                                   GPid         *child_pid,
+                                   GError      **error);
+
+void       gimp_spawn_set_cloexec (gint          fd);
+
+
+#endif /* __GIMP_SPAWN_H__ */
diff --git a/app/core/gimp-tags.c b/app/core/gimp-tags.c
new file mode 100644
index 0000000..5efedb9
--- /dev/null
+++ b/app/core/gimp-tags.c
@@ -0,0 +1,271 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimp-tags.c
+ * Copyright (C) 2009 Aurimas Juška <aurisj@svn.gnome.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gio/gio.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpmath/gimpmath.h"
+
+#include "core-types.h"
+
+#include "config/gimpxmlparser.h"
+
+#include "gimp-utils.h"
+#include "gimp-tags.h"
+
+#include "gimp-intl.h"
+
+
+#define GIMP_TAGS_FILE "tags.xml"
+
+typedef struct
+{
+  const gchar *locale;
+  GString     *buf;
+  gboolean     locale_matches;
+} GimpTagsInstaller;
+
+
+static  void        gimp_tags_installer_load_start_element (GMarkupParseContext *context,
+                                                            const gchar         *element_name,
+                                                            const gchar        **attribute_names,
+                                                            const gchar        **attribute_values,
+                                                            gpointer             user_data,
+                                                            GError             **error);
+static void         gimp_tags_installer_load_end_element   (GMarkupParseContext *context,
+                                                            const gchar         *element_name,
+                                                            gpointer             user_data,
+                                                            GError             **error);
+static void         gimp_tags_installer_load_text          (GMarkupParseContext *context,
+                                                            const gchar         *text,
+                                                            gsize                text_len,
+                                                            gpointer             user_data,
+                                                            GError             **error);
+static const gchar* attribute_name_to_value                (const gchar        **attribute_names,
+                                                            const gchar        **attribute_values,
+                                                            const gchar         *name);
+
+
+gboolean
+gimp_tags_user_install (void)
+{
+  GFile             *file;
+  GOutputStream     *output;
+  GMarkupParser      markup_parser;
+  GimpXmlParser     *xml_parser;
+  const char        *tags_locale;
+  GimpTagsInstaller  tags_installer = { 0, };
+  GError            *error          = NULL;
+  gboolean           result         = TRUE;
+
+  /* This is a special string to specify the language identifier to
+   * look for in the gimp-tags-default.xml file. Please translate the
+   * C in it according to the name of the po file used for
+   * gimp-tags-default.xml. E.g. lithuanian for the translation,
+   * that would be "tags-locale:lt".
+   */
+  tags_locale = _("tags-locale:C");
+
+  if (g_str_has_prefix (tags_locale, "tags-locale:"))
+    {
+      tags_locale += strlen ("tags-locale:");
+
+      if (*tags_locale && *tags_locale != 'C')
+        tags_installer.locale = tags_locale;
+    }
+  else
+    {
+      g_warning ("Wrong translation for 'tags-locale:', fix the translation!");
+    }
+
+  tags_installer.buf = g_string_new (NULL);
+
+  g_string_append (tags_installer.buf, "<?xml version='1.0' encoding='UTF-8'?>\n");
+  g_string_append (tags_installer.buf, "<tags>\n");
+
+  markup_parser.start_element = gimp_tags_installer_load_start_element;
+  markup_parser.end_element   = gimp_tags_installer_load_end_element;
+  markup_parser.text          = gimp_tags_installer_load_text;
+  markup_parser.passthrough   = NULL;
+  markup_parser.error         = NULL;
+
+  xml_parser = gimp_xml_parser_new (&markup_parser, &tags_installer);
+
+  file = gimp_data_directory_file ("tags", "gimp-tags-default.xml", NULL);
+  result = gimp_xml_parser_parse_gfile (xml_parser, file, &error);
+  g_object_unref (file);
+
+  gimp_xml_parser_free (xml_parser);
+
+  if (! result)
+    {
+      g_string_free (tags_installer.buf, TRUE);
+      return FALSE;
+    }
+
+  g_string_append (tags_installer.buf, "\n</tags>\n");
+
+  file = gimp_directory_file (GIMP_TAGS_FILE, NULL);
+
+  output = G_OUTPUT_STREAM (g_file_replace (file,
+                                            NULL, FALSE, G_FILE_CREATE_NONE,
+                                            NULL, &error));
+  if (! output)
+    {
+      g_printerr ("%s\n", error->message);
+      result = FALSE;
+    }
+  else if (! g_output_stream_write_all (output,
+                                        tags_installer.buf->str,
+                                        tags_installer.buf->len,
+                                        NULL, NULL, &error))
+    {
+      GCancellable *cancellable = g_cancellable_new ();
+
+      g_printerr (_("Error writing '%s': %s"),
+                  gimp_file_get_utf8_name (file), error->message);
+      result = FALSE;
+
+      /* Cancel the overwrite initiated by g_file_replace(). */
+      g_cancellable_cancel (cancellable);
+      g_output_stream_close (output, cancellable, NULL);
+      g_object_unref (cancellable);
+    }
+  else if (! g_output_stream_close (output, NULL, &error))
+    {
+      g_printerr (_("Error closing '%s': %s"),
+                  gimp_file_get_utf8_name (file), error->message);
+      result = FALSE;
+    }
+
+  if (output)
+    g_object_unref (output);
+
+  g_clear_error (&error);
+  g_object_unref (file);
+  g_string_free (tags_installer.buf, TRUE);
+
+  return result;
+}
+
+static  void
+gimp_tags_installer_load_start_element (GMarkupParseContext  *context,
+                                        const gchar          *element_name,
+                                        const gchar         **attribute_names,
+                                        const gchar         **attribute_values,
+                                        gpointer              user_data,
+                                        GError              **error)
+{
+  GimpTagsInstaller *tags_installer = user_data;
+
+  if (! strcmp (element_name, "resource"))
+    {
+      g_string_append_printf (tags_installer->buf, "\n  <resource");
+
+      while (*attribute_names)
+        {
+          g_string_append_printf (tags_installer->buf, " %s=\"%s\"",
+                                  *attribute_names, *attribute_values);
+
+          attribute_names++;
+          attribute_values++;
+        }
+
+      g_string_append_printf (tags_installer->buf, ">\n");
+    }
+  else if (! strcmp (element_name, "thetag"))
+    {
+      const char *current_locale;
+
+      current_locale = attribute_name_to_value (attribute_names, attribute_values,
+                                                "xml:lang");
+
+      if (current_locale && tags_installer->locale)
+        {
+          tags_installer->locale_matches = ! strcmp (current_locale,
+                                                     tags_installer->locale);
+        }
+      else
+        {
+          tags_installer->locale_matches = (current_locale ==
+                                            tags_installer->locale);
+        }
+    }
+}
+
+static void
+gimp_tags_installer_load_end_element (GMarkupParseContext  *context,
+                                      const gchar          *element_name,
+                                      gpointer              user_data,
+                                      GError              **error)
+{
+  GimpTagsInstaller *tags_installer = user_data;
+
+  if (strcmp (element_name, "resource") == 0)
+    {
+      g_string_append (tags_installer->buf, "  </resource>\n");
+    }
+}
+
+static void
+gimp_tags_installer_load_text (GMarkupParseContext  *context,
+                               const gchar          *text,
+                               gsize                 text_len,
+                               gpointer              user_data,
+                               GError              **error)
+{
+  GimpTagsInstaller *tags_installer = user_data;
+  const gchar       *current_element;
+  gchar             *tag_string;
+
+  current_element = g_markup_parse_context_get_element (context);
+
+  if (tags_installer->locale_matches &&
+      current_element &&
+      strcmp (current_element, "thetag") == 0)
+    {
+      tag_string = g_markup_escape_text (text, text_len);
+      g_string_append_printf (tags_installer->buf, "    <tag>%s</tag>\n",
+                              tag_string);
+      g_free (tag_string);
+    }
+}
+
+static const gchar *
+attribute_name_to_value (const gchar **attribute_names,
+                         const gchar **attribute_values,
+                         const gchar  *name)
+{
+  while (*attribute_names)
+    {
+      if (! strcmp (*attribute_names, name))
+        {
+          return *attribute_values;
+        }
+
+      attribute_names++;
+      attribute_values++;
+    }
+
+  return NULL;
+}
diff --git a/app/core/gimp-tags.h b/app/core/gimp-tags.h
new file mode 100644
index 0000000..8f52dce
--- /dev/null
+++ b/app/core/gimp-tags.h
@@ -0,0 +1,25 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1997 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_TAGS_H__
+#define __GIMP_TAGS_H__
+
+
+gboolean gimp_tags_user_install (void);
+
+
+#endif  /*  __GIMP_TAGS_H__  */
diff --git a/app/core/gimp-templates.c b/app/core/gimp-templates.c
new file mode 100644
index 0000000..ba0800d
--- /dev/null
+++ b/app/core/gimp-templates.c
@@ -0,0 +1,213 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1997 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpconfig/gimpconfig.h"
+
+#include "core-types.h"
+
+#include "gimp.h"
+#include "gimp-templates.h"
+#include "gimplist.h"
+#include "gimptemplate.h"
+
+
+/* functions to load and save the gimp templates files */
+
+void
+gimp_templates_load (Gimp *gimp)
+{
+  GFile  *file;
+  GError *error = NULL;
+
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+  g_return_if_fail (GIMP_IS_LIST (gimp->templates));
+
+  file = gimp_directory_file ("templaterc", NULL);
+
+  if (gimp->be_verbose)
+    g_print ("Parsing '%s'\n", gimp_file_get_utf8_name (file));
+
+  if (! gimp_config_deserialize_gfile (GIMP_CONFIG (gimp->templates),
+                                       file, NULL, &error))
+    {
+      if (error->code == GIMP_CONFIG_ERROR_OPEN_ENOENT)
+        {
+          g_clear_error (&error);
+          g_object_unref (file);
+
+          file = gimp_sysconf_directory_file ("templaterc", NULL);
+
+          if (! gimp_config_deserialize_gfile (GIMP_CONFIG (gimp->templates),
+                                               file, NULL, &error))
+            {
+              gimp_message_literal (gimp, NULL, GIMP_MESSAGE_ERROR,
+                                    error->message);
+            }
+        }
+      else
+        {
+          gimp_message_literal (gimp, NULL, GIMP_MESSAGE_ERROR, error->message);
+        }
+
+      g_clear_error (&error);
+    }
+
+  gimp_list_reverse (GIMP_LIST (gimp->templates));
+
+  g_object_unref (file);
+}
+
+void
+gimp_templates_save (Gimp *gimp)
+{
+  const gchar *header =
+    "GIMP templaterc\n"
+    "\n"
+    "This file will be entirely rewritten each time you exit.";
+  const gchar *footer =
+    "end of templaterc";
+
+  GFile  *file;
+  GError *error = NULL;
+
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+  g_return_if_fail (GIMP_IS_LIST (gimp->templates));
+
+  file = gimp_directory_file ("templaterc", NULL);
+
+  if (gimp->be_verbose)
+    g_print ("Writing '%s'\n", gimp_file_get_utf8_name (file));
+
+  if (! gimp_config_serialize_to_gfile (GIMP_CONFIG (gimp->templates),
+                                        file,
+                                        header, footer, NULL,
+                                        &error))
+    {
+      gimp_message_literal (gimp, NULL, GIMP_MESSAGE_ERROR, error->message);
+      g_error_free (error);
+    }
+
+  g_object_unref (file);
+}
+
+
+/*  just like gimp_list_get_child_by_name() but matches case-insensitive
+ *  and dpi/ppi-insensitive
+ */
+static GimpObject *
+gimp_templates_migrate_get_child_by_name (GimpContainer *container,
+                                          const gchar   *name)
+{
+  GimpList   *list   = GIMP_LIST (container);
+  GimpObject *retval = NULL;
+  GList      *glist;
+
+  for (glist = list->queue->head; glist; glist = g_list_next (glist))
+    {
+      GimpObject *object = glist->data;
+      gchar      *str1   = g_ascii_strdown (gimp_object_get_name (object), -1);
+      gchar      *str2   = g_ascii_strdown (name, -1);
+
+      if (! strcmp (str1, str2))
+        {
+          retval = object;
+        }
+      else
+        {
+          gchar *dpi = strstr (str1, "dpi");
+
+          if (dpi)
+            {
+              memcpy (dpi, "ppi", 3);
+
+              g_print ("replaced: %s\n", str1);
+
+              if (! strcmp (str1, str2))
+                retval = object;
+            }
+        }
+
+      g_free (str1);
+      g_free (str2);
+    }
+
+  return retval;
+}
+
+/**
+ * gimp_templates_migrate:
+ * @olddir: the old user directory
+ *
+ * Migrating the templaterc from GIMP 2.0 to GIMP 2.2 needs this special
+ * hack since we changed the way that units are handled. This function
+ * merges the user's templaterc with the systemwide templaterc. The goal
+ * is to replace the unit for a couple of default templates with "pixels".
+ **/
+void
+gimp_templates_migrate (const gchar *olddir)
+{
+  GimpContainer *templates = gimp_list_new (GIMP_TYPE_TEMPLATE, TRUE);
+  GFile         *file      = gimp_directory_file ("templaterc", NULL);
+
+  if (gimp_config_deserialize_gfile (GIMP_CONFIG (templates), file,
+                                     NULL, NULL))
+    {
+      GFile *sysconf_file;
+
+      sysconf_file = gimp_sysconf_directory_file ("templaterc", NULL);
+
+      if (olddir && (strstr (olddir, "2.0") || strstr (olddir, "2.2")))
+        {
+          /* We changed the spelling of a couple of template names:
+           *
+           * - from upper to lower case between 2.0 and 2.2
+           * - from "dpi" to "ppi" between 2.2 and 2.4
+           */
+          GimpContainerClass *class = GIMP_CONTAINER_GET_CLASS (templates);
+          gpointer            func  = class->get_child_by_name;
+
+          class->get_child_by_name = gimp_templates_migrate_get_child_by_name;
+
+          gimp_config_deserialize_gfile (GIMP_CONFIG (templates),
+                                         sysconf_file, NULL, NULL);
+
+          class->get_child_by_name = func;
+        }
+      else
+        {
+          gimp_config_deserialize_gfile (GIMP_CONFIG (templates),
+                                         sysconf_file, NULL, NULL);
+        }
+
+      g_object_unref (sysconf_file);
+
+      gimp_list_reverse (GIMP_LIST (templates));
+
+      gimp_config_serialize_to_gfile (GIMP_CONFIG (templates), file,
+                                      NULL, NULL, NULL, NULL);
+    }
+
+  g_object_unref (file);
+}
diff --git a/app/core/gimp-templates.h b/app/core/gimp-templates.h
new file mode 100644
index 0000000..3dc0fde
--- /dev/null
+++ b/app/core/gimp-templates.h
@@ -0,0 +1,28 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1997 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_TEMPLATES_H__
+#define __GIMP_TEMPLATES_H__
+
+
+void  gimp_templates_load    (Gimp        *gimp);
+void  gimp_templates_save    (Gimp        *gimp);
+
+void  gimp_templates_migrate (const gchar *olddir);
+
+
+#endif  /*  __GIMP_TEMPLATES_H__  */
diff --git a/app/core/gimp-transform-3d-utils.c b/app/core/gimp-transform-3d-utils.c
new file mode 100644
index 0000000..5ea9f81
--- /dev/null
+++ b/app/core/gimp-transform-3d-utils.c
@@ -0,0 +1,359 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimp-3d-transform-utils.c
+ * Copyright (C) 2019 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <glib-object.h>
+
+#include "libgimpmath/gimpmath.h"
+
+#include "core-types.h"
+
+#include "gimp-transform-3d-utils.h"
+
+
+#define MIN_FOCAL_LENGTH 0.01
+
+
+gdouble
+gimp_transform_3d_angle_of_view_to_focal_length (gdouble angle_of_view,
+                                                 gdouble width,
+                                                 gdouble height)
+{
+  return MAX (width, height) / (2.0 * tan (angle_of_view / 2.0));
+}
+
+gdouble
+gimp_transform_3d_focal_length_to_angle_of_view (gdouble focal_length,
+                                                 gdouble width,
+                                                 gdouble height)
+{
+  return 2.0 * atan (MAX (width, height) / (2.0 * focal_length));
+}
+
+gint
+gimp_transform_3d_permutation_to_rotation_order (const gint permutation[3])
+{
+  if (permutation[1] == (permutation[0] + 1) % 3)
+    return permutation[0] << 1;
+  else
+    return (permutation[2] << 1) + 1;
+}
+
+void
+gimp_transform_3d_rotation_order_to_permutation (gint rotation_order,
+                                                 gint permutation[3])
+{
+  gboolean reverse = rotation_order & 1;
+  gint     shift   = rotation_order >> 1;
+  gint i;
+
+  for (i = 0; i < 3; i++)
+    permutation[reverse ? 2 - i : i] = (i + shift) % 3;
+}
+
+gint
+gimp_transform_3d_rotation_order_reverse (gint rotation_order)
+{
+  return rotation_order ^ 1;
+}
+
+void
+gimp_transform_3d_vector3_rotate (GimpVector3       *vector,
+                                  const GimpVector3 *axis)
+{
+  GimpVector3 normal;
+  GimpVector3 proj;
+  GimpVector3 u, v;
+  gdouble     angle;
+
+  angle = gimp_vector3_length (axis);
+
+  if (angle == 0.0)
+    return;
+
+  normal = gimp_vector3_mul_val (*axis, 1.0 / angle);
+
+  proj = gimp_vector3_mul_val (normal,
+                               gimp_vector3_inner_product_val (*vector,
+                                                               normal));
+
+  u = gimp_vector3_sub_val (*vector, proj);
+  v = gimp_vector3_cross_product_val (u, normal);
+
+  gimp_vector3_mul (&u, cos (angle));
+  gimp_vector3_mul (&v, sin (angle));
+
+  *vector = proj;
+
+  gimp_vector3_add (vector, vector, &u);
+  gimp_vector3_add (vector, vector, &v);
+}
+
+GimpVector3
+gimp_transform_3d_vector3_rotate_val (GimpVector3 vector,
+                                      GimpVector3 axis)
+{
+  gimp_transform_3d_vector3_rotate (&vector, &axis);
+
+  return vector;
+}
+
+void
+gimp_transform_3d_matrix3_to_matrix4 (const GimpMatrix3 *matrix3,
+                                      GimpMatrix4       *matrix4,
+                                      gint               axis)
+{
+  gint i, j;
+  gint k, l;
+
+  for (i = 0; i < 4; i++)
+    {
+      if (i == axis)
+        {
+          matrix4->coeff[i][i] = 1.0;
+        }
+      else
+        {
+          matrix4->coeff[axis][i] = 0.0;
+          matrix4->coeff[i][axis] = 0.0;
+        }
+    }
+
+  for (i = 0; i < 3; i++)
+    {
+      k = i + (i >= axis);
+
+      for (j = 0; j < 3; j++)
+        {
+          l = j + (j >= axis);
+
+          matrix4->coeff[k][l] = matrix3->coeff[i][j];
+        }
+    }
+}
+
+void
+gimp_transform_3d_matrix4_to_matrix3 (const GimpMatrix4 *matrix4,
+                                      GimpMatrix3       *matrix3,
+                                      gint               axis)
+{
+  gint i, j;
+  gint k, l;
+
+  for (i = 0; i < 3; i++)
+    {
+      k = i + (i >= axis);
+
+      for (j = 0; j < 3; j++)
+        {
+          l = j + (j >= axis);
+
+          matrix3->coeff[i][j] = matrix4->coeff[k][l];
+        }
+    }
+}
+
+void
+gimp_transform_3d_matrix4_translate (GimpMatrix4 *matrix,
+                                     gdouble      x,
+                                     gdouble      y,
+                                     gdouble      z)
+{
+  gint i;
+
+  for (i = 0; i < 4; i++)
+    matrix->coeff[0][i] += x * matrix->coeff[3][i];
+
+  for (i = 0; i < 4; i++)
+    matrix->coeff[1][i] += y * matrix->coeff[3][i];
+
+  for (i = 0; i < 4; i++)
+    matrix->coeff[2][i] += z * matrix->coeff[3][i];
+}
+
+void
+gimp_transform_3d_matrix4_rotate (GimpMatrix4       *matrix,
+                                  const GimpVector3 *axis)
+{
+  GimpMatrix4 rotation;
+  GimpVector3 v;
+
+  v = gimp_transform_3d_vector3_rotate_val ((GimpVector3) {1.0, 0.0, 0.0},
+                                            *axis);
+
+  rotation.coeff[0][0] = v.x;
+  rotation.coeff[1][0] = v.y;
+  rotation.coeff[2][0] = v.z;
+  rotation.coeff[3][0] = 0.0;
+
+  v = gimp_transform_3d_vector3_rotate_val ((GimpVector3) {0.0, 1.0, 0.0},
+                                            *axis);
+
+  rotation.coeff[0][1] = v.x;
+  rotation.coeff[1][1] = v.y;
+  rotation.coeff[2][1] = v.z;
+  rotation.coeff[3][1] = 0.0;
+
+  v = gimp_transform_3d_vector3_rotate_val ((GimpVector3) {0.0, 0.0, 1.0},
+                                            *axis);
+
+  rotation.coeff[0][2] = v.x;
+  rotation.coeff[1][2] = v.y;
+  rotation.coeff[2][2] = v.z;
+  rotation.coeff[3][2] = 0.0;
+
+  rotation.coeff[0][3] = 0.0;
+  rotation.coeff[1][3] = 0.0;
+  rotation.coeff[2][3] = 0.0;
+  rotation.coeff[3][3] = 1.0;
+
+  gimp_matrix4_mult (&rotation, matrix);
+}
+
+void
+gimp_transform_3d_matrix4_rotate_standard (GimpMatrix4 *matrix,
+                                           gint         axis,
+                                           gdouble      angle)
+{
+  gdouble v[3] = {};
+
+  v[axis] = angle;
+
+  gimp_transform_3d_matrix4_rotate (matrix, &(GimpVector3) {v[0], v[1], v[2]});
+}
+
+void
+gimp_transform_3d_matrix4_rotate_euler (GimpMatrix4 *matrix,
+                                        gint         rotation_order,
+                                        gdouble      angle_x,
+                                        gdouble      angle_y,
+                                        gdouble      angle_z,
+                                        gdouble      pivot_x,
+                                        gdouble      pivot_y,
+                                        gdouble      pivot_z)
+{
+  const gdouble angles[3] = {angle_x, angle_y, angle_z};
+  gint          permutation[3];
+  gint          i;
+
+  gimp_transform_3d_rotation_order_to_permutation (rotation_order, permutation);
+
+  gimp_transform_3d_matrix4_translate (matrix, -pivot_x, -pivot_y, -pivot_z);
+
+  for (i = 0; i < 3; i++)
+    {
+      gimp_transform_3d_matrix4_rotate_standard (matrix,
+                                                 permutation[i],
+                                                 angles[permutation[i]]);
+    }
+
+  gimp_transform_3d_matrix4_translate (matrix, +pivot_x, +pivot_y, +pivot_z);
+}
+
+void
+gimp_transform_3d_matrix4_rotate_euler_decompose (GimpMatrix4 *matrix,
+                                                  gint         rotation_order,
+                                                  gdouble     *angle_x,
+                                                  gdouble     *angle_y,
+                                                  gdouble     *angle_z)
+{
+  GimpMatrix4     m = *matrix;
+  gdouble * const angles[3] = {angle_x, angle_y, angle_z};
+  gint            permutation[3];
+  gboolean        forward;
+
+  gimp_transform_3d_rotation_order_to_permutation (rotation_order, permutation);
+
+  forward = permutation[1] == (permutation[0] + 1) % 3;
+
+  *angles[permutation[2]] = atan2 (m.coeff[permutation[1]][permutation[0]],
+                                   m.coeff[permutation[0]][permutation[0]]);
+
+  if (forward)
+    *angles[permutation[2]] *= -1.0;
+
+  gimp_transform_3d_matrix4_rotate_standard (&m,
+                                             permutation[2],
+                                             -*angles[permutation[2]]);
+
+  *angles[permutation[1]] = atan2 (m.coeff[permutation[2]][permutation[0]],
+                                   m.coeff[permutation[0]][permutation[0]]);
+
+  if (! forward)
+    *angles[permutation[1]] *= -1.0;
+
+  gimp_transform_3d_matrix4_rotate_standard (&m,
+                                             permutation[1],
+                                             -*angles[permutation[1]]);
+
+  *angles[permutation[0]] = atan2 (m.coeff[permutation[2]][permutation[1]],
+                                   m.coeff[permutation[1]][permutation[1]]);
+
+  if (forward)
+    *angles[permutation[0]] *= -1.0;
+}
+
+void
+gimp_transform_3d_matrix4_perspective (GimpMatrix4 *matrix,
+                                       gdouble      camera_x,
+                                       gdouble      camera_y,
+                                       gdouble      camera_z)
+{
+  gint i;
+
+  camera_z = MIN (camera_z, -MIN_FOCAL_LENGTH);
+
+  gimp_transform_3d_matrix4_translate (matrix, -camera_x, -camera_y, 0.0);
+
+  for (i = 0; i < 4; i++)
+    matrix->coeff[3][i] += matrix->coeff[2][i] / -camera_z;
+
+  gimp_transform_3d_matrix4_translate (matrix, +camera_x, +camera_y, 0.0);
+}
+
+void
+gimp_transform_3d_matrix (GimpMatrix3 *matrix,
+                          gdouble      camera_x,
+                          gdouble      camera_y,
+                          gdouble      camera_z,
+                          gdouble      offset_x,
+                          gdouble      offset_y,
+                          gdouble      offset_z,
+                          gint         rotation_order,
+                          gdouble      angle_x,
+                          gdouble      angle_y,
+                          gdouble      angle_z,
+                          gdouble      pivot_x,
+                          gdouble      pivot_y,
+                          gdouble      pivot_z)
+{
+  GimpMatrix4 m;
+
+  gimp_matrix4_identity (&m);
+  gimp_transform_3d_matrix4_rotate_euler (&m,
+                                          rotation_order,
+                                          angle_x, angle_y, angle_z,
+                                          pivot_x, pivot_y, pivot_z);
+  gimp_transform_3d_matrix4_translate (&m, offset_x, offset_y, offset_z);
+  gimp_transform_3d_matrix4_perspective (&m, camera_x, camera_y, camera_z);
+
+  gimp_transform_3d_matrix4_to_matrix3 (&m, matrix, 2);
+}
diff --git a/app/core/gimp-transform-3d-utils.h b/app/core/gimp-transform-3d-utils.h
new file mode 100644
index 0000000..92f6795
--- /dev/null
+++ b/app/core/gimp-transform-3d-utils.h
@@ -0,0 +1,95 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimp-3d-transform-utils.h
+ * Copyright (C) 2019 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_TRANSFORM_3D_UTILS_H__
+#define __GIMP_TRANSFORM_3D_UTILS_H__
+
+
+gdouble       gimp_transform_3d_angle_of_view_to_focal_length   (gdouble            angle_of_view,
+                                                                 gdouble            width,
+                                                                 gdouble            height);
+gdouble       gimp_transform_3d_focal_length_to_angle_of_view   (gdouble            focal_length,
+                                                                 gdouble            width,
+                                                                 gdouble            height);
+
+gint          gimp_transform_3d_permutation_to_rotation_order   (const gint         permutation[3]);
+void          gimp_transform_3d_rotation_order_to_permutation   (gint               rotation_order,
+                                                                 gint               permutation[3]);
+gint          gimp_transform_3d_rotation_order_reverse          (gint               rotation_order);
+
+void          gimp_transform_3d_vector3_rotate                  (GimpVector3       *vector,
+                                                                 const GimpVector3 *axis);
+GimpVector3   gimp_transform_3d_vector3_rotate_val              (GimpVector3        vector,
+                                                                 GimpVector3        axis);
+
+void          gimp_transform_3d_matrix3_to_matrix4              (const GimpMatrix3 *matrix3,
+                                                                 GimpMatrix4       *matrix4,
+                                                                 gint               axis);
+void          gimp_transform_3d_matrix4_to_matrix3              (const GimpMatrix4 *matrix4,
+                                                                 GimpMatrix3       *matrix3,
+                                                                 gint               axis);
+
+void          gimp_transform_3d_matrix4_translate               (GimpMatrix4       *matrix,
+                                                                 gdouble            x,
+                                                                 gdouble            y,
+                                                                 gdouble            z);
+
+void          gimp_transform_3d_matrix4_rotate                  (GimpMatrix4       *matrix,
+                                                                 const GimpVector3 *axis);
+void          gimp_transform_3d_matrix4_rotate_standard         (GimpMatrix4       *matrix,
+                                                                 gint               axis,
+                                                                 gdouble            angle);
+
+void          gimp_transform_3d_matrix4_rotate_euler            (GimpMatrix4       *matrix,
+                                                                 gint               rotation_order,
+                                                                 gdouble            angle_x,
+                                                                 gdouble            angle_y,
+                                                                 gdouble            angle_z,
+                                                                 gdouble            pivot_x,
+                                                                 gdouble            pivot_y,
+                                                                 gdouble            pivot_z);
+void          gimp_transform_3d_matrix4_rotate_euler_decompose  (GimpMatrix4       *matrix,
+                                                                 gint               rotation_order,
+                                                                 gdouble           *angle_x,
+                                                                 gdouble           *angle_y,
+                                                                 gdouble           *angle_z);
+
+void          gimp_transform_3d_matrix4_perspective             (GimpMatrix4       *matrix,
+                                                                 gdouble            camera_x,
+                                                                 gdouble            camera_y,
+                                                                 gdouble            camera_z);
+
+void          gimp_transform_3d_matrix                          (GimpMatrix3       *matrix,
+                                                                 gdouble            camera_x,
+                                                                 gdouble            camera_y,
+                                                                 gdouble            camera_z,
+                                                                 gdouble            offset_x,
+                                                                 gdouble            offset_y,
+                                                                 gdouble            offset_z,
+                                                                 gint               rotation_order,
+                                                                 gdouble            angle_x,
+                                                                 gdouble            angle_y,
+                                                                 gdouble            angle_z,
+                                                                 gdouble            pivot_x,
+                                                                 gdouble            pivot_y,
+                                                                 gdouble            pivot_z);
+
+
+#endif /* __GIMP_TRANSFORM_3D_UTILS_H__ */
diff --git a/app/core/gimp-transform-resize.c b/app/core/gimp-transform-resize.c
new file mode 100644
index 0000000..7aabd67
--- /dev/null
+++ b/app/core/gimp-transform-resize.c
@@ -0,0 +1,841 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-2001 Spencer Kimball, Peter Mattis, and others
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <gio/gio.h>
+#include <gegl.h>
+
+#include "libgimpmath/gimpmath.h"
+
+#include "core-types.h"
+
+#include "gimp-transform-resize.h"
+#include "gimp-transform-utils.h"
+#include "gimp-utils.h"
+
+
+#if defined (HAVE_ISFINITE)
+#define FINITE(x) isfinite(x)
+#elif defined (HAVE_FINITE)
+#define FINITE(x) finite(x)
+#elif defined (G_OS_WIN32)
+#define FINITE(x) _finite(x)
+#else
+#error "no FINITE() implementation available?!"
+#endif
+
+#define EPSILON 0.00000001
+
+
+typedef struct
+{
+  GimpVector2 a, b, c, d;
+  gdouble     area;
+  gdouble     aspect;
+} Rectangle;
+
+
+static void      gimp_transform_resize_adjust        (const GimpVector2 *points,
+                                                      gint               n_points,
+                                                      gint              *x1,
+                                                      gint              *y1,
+                                                      gint              *x2,
+                                                      gint              *y2);
+static void      gimp_transform_resize_crop          (const GimpVector2 *points,
+                                                      gint               n_points,
+                                                      gdouble            aspect,
+                                                      gint              *x1,
+                                                      gint              *y1,
+                                                      gint              *x2,
+                                                      gint              *y2);
+
+static void      add_rectangle                       (const GimpVector2 *points,
+                                                      gint               n_points,
+                                                      Rectangle         *r,
+                                                      GimpVector2        a,
+                                                      GimpVector2        b,
+                                                      GimpVector2        c,
+                                                      GimpVector2        d);
+static gboolean  intersect                           (GimpVector2        a,
+                                                      GimpVector2        b,
+                                                      GimpVector2        c,
+                                                      GimpVector2        d,
+                                                      GimpVector2       *i);
+static gboolean  intersect_x                         (GimpVector2        a,
+                                                      GimpVector2        b,
+                                                      GimpVector2        c,
+                                                      GimpVector2       *i);
+static gboolean  intersect_y                         (GimpVector2        a,
+                                                      GimpVector2        b,
+                                                      GimpVector2        c,
+                                                      GimpVector2       *i);
+static gboolean  in_poly                             (const GimpVector2 *points,
+                                                      gint               n_points,
+                                                      GimpVector2        p);
+static gboolean  point_on_border                     (const GimpVector2 *points,
+                                                      gint               n_points,
+                                                      GimpVector2        p);
+
+static void      find_two_point_rectangle            (Rectangle         *r,
+                                                      const GimpVector2 *points,
+                                                      gint               n_points,
+                                                      gint               p);
+static void      find_three_point_rectangle_corner   (Rectangle         *r,
+                                                      const GimpVector2 *points,
+                                                      gint               n_points,
+                                                      gint               p);
+static void      find_three_point_rectangle          (Rectangle          *r,
+                                                      const GimpVector2 *points,
+                                                      gint               n_points,
+                                                      gint               p);
+static void      find_three_point_rectangle_triangle (Rectangle         *r,
+                                                      const GimpVector2 *points,
+                                                      gint               n_points,
+                                                      gint               p);
+static void      find_maximum_aspect_rectangle       (Rectangle          *r,
+                                                      const GimpVector2 *points,
+                                                      gint               n_points,
+                                                      gint               p);
+
+
+/*
+ * This function wants to be passed the inverse transformation matrix!!
+ */
+gboolean
+gimp_transform_resize_boundary (const GimpMatrix3   *inv,
+                                GimpTransformResize  resize,
+                                gdouble              u1,
+                                gdouble              v1,
+                                gdouble              u2,
+                                gdouble              v2,
+                                gint                *x1,
+                                gint                *y1,
+                                gint                *x2,
+                                gint                *y2)
+{
+  GimpVector2 bounds[4];
+  GimpVector2 points[5];
+  gint        n_points;
+  gboolean    valid;
+  gint        i;
+
+  g_return_val_if_fail (inv != NULL, FALSE);
+
+  /*  initialize with the original boundary  */
+  *x1 = floor (u1);
+  *y1 = floor (v1);
+  *x2 = ceil  (u2);
+  *y2 = ceil  (v2);
+
+  /* if clipping then just return the original rectangle */
+  if (resize == GIMP_TRANSFORM_RESIZE_CLIP)
+    return TRUE;
+
+  bounds[0] = (GimpVector2) { u1, v1 };
+  bounds[1] = (GimpVector2) { u2, v1 };
+  bounds[2] = (GimpVector2) { u2, v2 };
+  bounds[3] = (GimpVector2) { u1, v2 };
+
+  gimp_transform_polygon (inv, bounds, 4, TRUE,
+                          points, &n_points);
+
+  valid = (n_points >= 2);
+
+  /*  check if the transformation matrix is valid at all  */
+  for (i = 0; i < n_points && valid; i++)
+    valid = (FINITE (points[i].x) && FINITE (points[i].y));
+
+  if (! valid)
+    {
+      /* since there is no sensible way to deal with this, just do the same as
+       * with GIMP_TRANSFORM_RESIZE_CLIP: return
+       */
+      return FALSE;
+    }
+
+  switch (resize)
+    {
+    case GIMP_TRANSFORM_RESIZE_ADJUST:
+      /* return smallest rectangle (with sides parallel to x- and y-axis)
+       * that surrounds the new points */
+      gimp_transform_resize_adjust (points, n_points,
+                                    x1, y1, x2, y2);
+      break;
+
+    case GIMP_TRANSFORM_RESIZE_CROP:
+      gimp_transform_resize_crop (points, n_points,
+                                  0.0,
+                                  x1, y1, x2, y2);
+      break;
+
+    case GIMP_TRANSFORM_RESIZE_CROP_WITH_ASPECT:
+      gimp_transform_resize_crop (points, n_points,
+                                  (u2 - u1) / (v2 - v1),
+                                  x1, y1, x2, y2);
+      break;
+
+    case GIMP_TRANSFORM_RESIZE_CLIP:
+      /* Remove warning about not handling all enum values. We handle
+       * this case in the beginning of the function
+       */
+      break;
+    }
+
+  /* ensure that resulting rectangle has at least area 1 */
+  if (*x1 == *x2)
+    (*x2)++;
+
+  if (*y1 == *y2)
+    (*y2)++;
+
+  return TRUE;
+}
+
+/* this calculates the smallest rectangle (with sides parallel to x- and
+ * y-axis) that contains the points d1 to d4
+ */
+static void
+gimp_transform_resize_adjust (const GimpVector2 *points,
+                              gint               n_points,
+                              gint              *x1,
+                              gint              *y1,
+                              gint              *x2,
+                              gint              *y2)
+{
+  GimpVector2 top_left;
+  GimpVector2 bottom_right;
+  gint        i;
+
+  top_left = bottom_right = points[0];
+
+  for (i = 1; i < n_points; i++)
+    {
+      top_left.x     = MIN (top_left.x,     points[i].x);
+      top_left.y     = MIN (top_left.y,     points[i].y);
+
+      bottom_right.x = MAX (bottom_right.x, points[i].x);
+      bottom_right.y = MAX (bottom_right.y, points[i].y);
+    }
+
+  *x1 = (gint) floor (top_left.x + EPSILON);
+  *y1 = (gint) floor (top_left.y + EPSILON);
+
+  *x2 = (gint) ceil (bottom_right.x - EPSILON);
+  *y2 = (gint) ceil (bottom_right.y - EPSILON);
+}
+
+static void
+gimp_transform_resize_crop (const GimpVector2 *orig_points,
+                            gint               n_points,
+                            gdouble            aspect,
+                            gint              *x1,
+                            gint              *y1,
+                            gint              *x2,
+                            gint              *y2)
+{
+  GimpVector2 points[5];
+  Rectangle   r;
+  GimpVector2 t,a;
+  gint        i, j;
+  gint        min;
+
+  memcpy (points, orig_points, sizeof (GimpVector2) * n_points);
+
+  /* find lowest, rightmost corner of surrounding rectangle */
+  a.x = 0;
+  a.y = 0;
+  for (i = 0; i < 4; i++)
+    {
+      if (points[i].x < a.x)
+        a.x = points[i].x;
+
+      if (points[i].y < a.y)
+        a.y = points[i].y;
+    }
+
+  /* and translate all the points to the first quadrant */
+  for (i = 0; i < n_points; i++)
+    {
+      points[i].x += (-a.x) * 2;
+      points[i].y += (-a.y) * 2;
+    }
+
+  /* find the convex hull using Jarvis's March as the points are passed
+   * in different orders due to gimp_matrix3_transform_point()
+   */
+  min = 0;
+  for (i = 0; i < n_points; i++)
+    {
+      if (points[i].y < points[min].y)
+        min = i;
+    }
+
+  t = points[0];
+  points[0] = points[min];
+  points[min] = t;
+
+  for (i = 1; i < n_points - 1; i++)
+    {
+      gdouble min_theta;
+      gdouble min_mag;
+      int next;
+
+      next = n_points - 1;
+      min_theta = 2.0 * G_PI;
+      min_mag = DBL_MAX;
+
+      for (j = i; j < n_points; j++)
+        {
+          gdouble theta;
+          gdouble sy;
+          gdouble sx;
+          gdouble mag;
+
+          sy = points[j].y - points[i - 1].y;
+          sx = points[j].x - points[i - 1].x;
+
+          if ((sx == 0.0) && (sy == 0.0))
+            {
+              next = j;
+              break;
+            }
+
+          theta = atan2 (-sy, -sx);
+          mag = (sx * sx) + (sy * sy);
+
+          if ((theta < min_theta) ||
+              ((theta == min_theta) && (mag < min_mag)))
+            {
+              min_theta = theta;
+              min_mag = mag;
+              next = j;
+            }
+        }
+
+      t = points[i];
+      points[i] = points[next];
+      points[next] = t;
+    }
+
+  /* reverse the order of points */
+  for (i = 0; i < n_points / 2; i++)
+    {
+      t                        = points[i];
+      points[i]                = points[n_points - i - 1];
+      points[n_points - i - 1] = t;
+    }
+
+  r.a.x = r.a.y = r.b.x = r.b.y = r.c.x = r.c.y = r.d.x = r.d.y = r.area = 0;
+  r.aspect = aspect;
+
+  if (aspect != 0)
+    {
+      for (i = 0; i < n_points; i++)
+        find_maximum_aspect_rectangle (&r, points, n_points, i);
+    }
+  else
+    {
+      for (i = 0; i < n_points; i++)
+        {
+          find_three_point_rectangle          (&r, points, n_points, i);
+          find_three_point_rectangle_corner   (&r, points, n_points, i);
+          find_two_point_rectangle            (&r, points, n_points, i);
+          find_three_point_rectangle_triangle (&r, points, n_points, i);
+        }
+    }
+
+  if (r.area == 0)
+    {
+      /* saveguard if something went wrong, adjust and give warning */
+      gimp_transform_resize_adjust (orig_points, n_points,
+                                    x1, y1, x2, y2);
+      g_printerr ("no rectangle found by algorithm, no cropping done\n");
+      return;
+    }
+  else
+    {
+      /* round and translate the calculated points back */
+      *x1 = floor (r.a.x + 0.5);
+      *y1 = floor (r.a.y + 0.5);
+      *x2 = ceil  (r.c.x - 0.5);
+      *y2 = ceil  (r.c.y - 0.5);
+
+      *x1 = *x1 - ((-a.x) * 2);
+      *y1 = *y1 - ((-a.y) * 2);
+      *x2 = *x2 - ((-a.x) * 2);
+      *y2 = *y2 - ((-a.y) * 2);
+      return;
+    }
+}
+
+static void
+find_three_point_rectangle (Rectangle         *r,
+                            const GimpVector2 *points,
+                            gint               n_points,
+                            gint               p)
+{
+  GimpVector2 a = points[p       % n_points];  /* 0 1 2 3 */
+  GimpVector2 b = points[(p + 1) % n_points];  /* 1 2 3 0 */
+  GimpVector2 c = points[(p + 2) % n_points];  /* 2 3 0 1 */
+  GimpVector2 d = points[(p + 3) % n_points];  /* 3 0 1 2 */
+  GimpVector2 i1;                              /* intersection point */
+  GimpVector2 i2;                              /* intersection point */
+  GimpVector2 i3;                              /* intersection point */
+
+  if (intersect_x (b, c, a,  &i1) &&
+      intersect_y (c, d, i1, &i2) &&
+      intersect_x (d, a, i2, &i3))
+    add_rectangle (points, n_points, r, i3, i3, i1, i1);
+
+  if (intersect_y (b, c, a,  &i1) &&
+      intersect_x (c, d, i1, &i2) &&
+      intersect_y (d, a, i2, &i3))
+    add_rectangle (points, n_points, r, i3, i3, i1, i1);
+
+  if (intersect_x (d, c, a,  &i1) &&
+      intersect_y (c, b, i1, &i2) &&
+      intersect_x (b, a, i2, &i3))
+    add_rectangle (points, n_points, r, i3, i3, i1, i1);
+
+  if (intersect_y (d, c, a,  &i1) &&
+      intersect_x (c, b, i1, &i2) &&
+      intersect_y (b, a, i2, &i3))
+    add_rectangle (points, n_points, r, i3, i3, i1, i1);
+}
+
+static void
+find_three_point_rectangle_corner (Rectangle         *r,
+                                   const GimpVector2 *points,
+                                   gint               n_points,
+                                   gint               p)
+{
+  GimpVector2 a = points[p       % n_points];  /* 0 1 2 3 */
+  GimpVector2 b = points[(p + 1) % n_points];  /* 1 2 3 0 */
+  GimpVector2 c = points[(p + 2) % n_points];  /* 2 3 0 2 */
+  GimpVector2 d = points[(p + 3) % n_points];  /* 3 0 2 1 */
+  GimpVector2 i1;                              /* intersection point */
+  GimpVector2 i2;                              /* intersection point */
+
+  if (intersect_x (b, c, a , &i1) &&
+      intersect_y (c, d, i1, &i2))
+    add_rectangle (points, n_points, r, a, a, i1, i2);
+
+  if (intersect_y (b, c, a , &i1) &&
+      intersect_x (c, d, i1, &i2))
+    add_rectangle (points, n_points, r, a, a, i1, i2);
+
+  if (intersect_x (c, d, a , &i1) &&
+      intersect_y (b, c, i1, &i2))
+    add_rectangle (points, n_points, r, a, a, i1, i2);
+
+  if (intersect_y (c, d, a , &i1) &&
+      intersect_x (b, c, i1, &i2))
+    add_rectangle (points, n_points, r, a, a, i1, i2);
+}
+
+static void
+find_two_point_rectangle (Rectangle         *r,
+                          const GimpVector2 *points,
+                          gint               n_points,
+                          gint               p)
+{
+  GimpVector2 a = points[ p      % n_points];  /* 0 1 2 3 */
+  GimpVector2 b = points[(p + 1) % n_points];  /* 1 2 3 0 */
+  GimpVector2 c = points[(p + 2) % n_points];  /* 2 3 0 1 */
+  GimpVector2 d = points[(p + 3) % n_points];  /* 3 0 1 2 */
+  GimpVector2 i1;                              /* intersection point */
+  GimpVector2 i2;                              /* intersection point */
+  GimpVector2 mid;                             /* Mid point */
+
+  add_rectangle (points, n_points, r, a, a, c, c);
+  add_rectangle (points, n_points, r, b, b, d, d);
+
+  if (intersect_x (c, b, a, &i1) &&
+      intersect_y (c, b, a, &i2))
+    {
+      mid.x = ( i1.x + i2.x ) / 2.0;
+      mid.y = ( i1.y + i2.y ) / 2.0;
+
+      add_rectangle (points, n_points, r, a, a, mid, mid);
+    }
+}
+
+static void
+find_three_point_rectangle_triangle (Rectangle         *r,
+                                     const GimpVector2 *points,
+                                     gint               n_points,
+                                     gint               p)
+{
+  GimpVector2 a = points[p       % n_points];  /* 0 1 2 3 */
+  GimpVector2 b = points[(p + 1) % n_points];  /* 1 2 3 0 */
+  GimpVector2 c = points[(p + 2) % n_points];  /* 2 3 0 1 */
+  GimpVector2 d = points[(p + 3) % n_points];  /* 3 0 1 2 */
+  GimpVector2 i1;                              /* intersection point */
+  GimpVector2 i2;                              /* intersection point */
+  GimpVector2 mid;
+
+  mid.x = (a.x + b.x) / 2.0;
+  mid.y = (a.y + b.y) / 2.0;
+
+  if (intersect_x (b, c, mid, &i1) &&
+      intersect_y (a, d, mid, &i2))
+    add_rectangle (points, n_points, r, mid, mid, i1, i2);
+
+  if (intersect_y (b, c, mid, &i1) &&
+      intersect_x (a, d, mid, &i2))
+    add_rectangle (points, n_points, r, mid, mid, i1, i2);
+
+  if (intersect_x (a, d, mid, &i1) &&
+      intersect_y (b, c, mid, &i2))
+    add_rectangle (points, n_points, r, mid, mid, i1, i2);
+
+  if (intersect_y (a, d, mid, &i1) &&
+      intersect_x (b, c, mid, &i2))
+    add_rectangle (points, n_points, r, mid, mid, i1, i2);
+}
+
+static void
+find_maximum_aspect_rectangle (Rectangle         *r,
+                               const GimpVector2 *points,
+                               gint               n_points,
+                               gint               p)
+{
+  GimpVector2 a = points[ p      % n_points];  /* 0 1 2 3 */
+  GimpVector2 b = points[(p + 1) % n_points];  /* 1 2 3 0 */
+  GimpVector2 c = points[(p + 2) % n_points];  /* 2 3 0 1 */
+  GimpVector2 d = points[(p + 3) % n_points];  /* 3 0 1 2 */
+  GimpVector2 i1;                              /* intersection point */
+  GimpVector2 i2;                              /* intersection point */
+  GimpVector2 i3;                              /* intersection point */
+
+  if (intersect_x (b, c, a, &i1))
+    {
+      i2.x = i1.x + 1.0 * r->aspect;
+      i2.y = i1.y + 1.0;
+
+      if (intersect (d, a, i1, i2, &i3))
+        add_rectangle (points, n_points, r, i1, i3, i1, i3);
+
+      if (intersect (a, b, i1, i2, &i3))
+        add_rectangle (points, n_points, r, i1, i3, i1, i3);
+
+      if (intersect (c, d, i1, i2, &i3))
+        add_rectangle (points, n_points, r, i1, i3, i1, i3);
+
+      i2.x = i1.x - 1.0 * r->aspect;
+      i2.y = i1.y + 1.0;
+
+      if (intersect (d, a, i1, i2, &i3))
+        add_rectangle (points, n_points, r, i1, i3, i1, i3);
+
+      if (intersect (a, b, i1, i2, &i3))
+        add_rectangle (points, n_points, r, i1, i3, i1, i3);
+
+      if (intersect (c, d, i1, i2, &i3))
+        add_rectangle (points, n_points, r, i1, i3, i1, i3);
+    }
+
+  if (intersect_y (b, c, a, &i1))
+    {
+      i2.x = i1.x + 1.0 * r->aspect;
+      i2.y = i1.y + 1.0;
+
+      if (intersect (d, a, i1, i2, &i3))
+        add_rectangle (points, n_points, r, i1, i3, i1, i3);
+
+      if (intersect (a, b, i1, i2, &i3))
+        add_rectangle (points, n_points, r, i1, i3, i1, i3);
+
+      if (intersect (c, d, i1, i2, &i3))
+        add_rectangle (points, n_points, r, i1, i3, i1, i3);
+
+      i2.x = i1.x - 1.0 * r->aspect;
+      i2.y = i1.y + 1.0;
+
+      if (intersect (d, a, i1, i2, &i3))
+        add_rectangle (points, n_points, r, i1, i3, i1, i3);
+
+      if (intersect (a, b, i1, i2, &i3))
+        add_rectangle (points, n_points, r, i1, i3, i1, i3);
+
+      if (intersect (c, d, i1, i2, &i3))
+        add_rectangle (points, n_points, r, i1, i3, i1, i3);
+    }
+
+  if (intersect_x (c, d, a,  &i1))
+    {
+      i2.x = i1.x + 1.0 * r->aspect;
+      i2.y = i1.y + 1.0;
+
+      if (intersect (d, a, i1, i2, &i3))
+        add_rectangle (points, n_points, r, i1, i3, i1, i3);
+
+      if (intersect (a, b, i1, i2, &i3))
+        add_rectangle (points, n_points, r, i1, i3, i1, i3);
+
+      if (intersect (b, c, i1, i2, &i3))
+        add_rectangle (points, n_points, r, i1, i3, i1, i3);
+
+      i2.x = i1.x - 1.0 * r->aspect;
+      i2.y = i1.y + 1.0;
+
+      if (intersect (d, a, i1, i2, &i3))
+        add_rectangle (points, n_points, r, i1, i3, i1, i3);
+
+      if (intersect (a, b, i1, i2, &i3))
+        add_rectangle (points, n_points, r, i1, i3, i1, i3);
+
+      if (intersect (b, c, i1, i2, &i3))
+        add_rectangle (points, n_points, r, i1, i3, i1, i3);
+    }
+
+  if (intersect_y (c, d, a,  &i1))
+    {
+      i2.x = i1.x + 1.0 * r->aspect;
+      i2.y = i1.y + 1.0;
+
+      if (intersect (d, a, i1, i2, &i3))
+        add_rectangle (points, n_points, r, i1, i3, i1, i3);
+
+      if (intersect (a, b, i1, i2, &i3))
+        add_rectangle (points, n_points, r, i1, i3, i1, i3);
+
+      if (intersect (b, c, i1, i2, &i3))
+        add_rectangle (points, n_points, r, i1, i3, i1, i3);
+
+      i2.x = i1.x - 1.0 * r->aspect;
+      i2.y = i1.y + 1.0;
+
+      if (intersect (d, a, i1, i2, &i3))
+        add_rectangle (points, n_points, r, i1, i3, i1, i3);
+
+      if (intersect (a, b, i1, i2, &i3))
+        add_rectangle (points, n_points, r, i1, i3, i1, i3);
+
+      if (intersect (b, c, i1, i2, &i3))
+        add_rectangle (points, n_points, r, i1, i3, i1, i3);
+    }
+}
+
+/* check if point is inside the polygon "points", if point is on border
+ * its still inside.
+ */
+static gboolean
+in_poly (const GimpVector2 *points,
+         gint               n_points,
+         GimpVector2        p)
+{
+  GimpVector2 p1, p2;
+  gint  counter = 0;
+  gint  i;
+
+  p1 = points[0];
+
+  for (i = 1; i <= n_points; i++)
+    {
+      p2 = points[i % n_points];
+
+      if (p.y > MIN (p1.y, p2.y))
+        {
+          if (p.y <= MAX (p1.y, p2.y))
+            {
+              if (p.x <= MAX (p1.x, p2.x))
+                {
+                  if (p1.y != p2.y)
+                    {
+                      gdouble xinters = ((p.y - p1.y) * (p2.x - p1.x) /
+                                         (p2.y - p1.y) + p1.x);
+
+                      if (p1.x == p2.x || p.x <= xinters)
+                        counter++;
+                    }
+                }
+            }
+        }
+
+      p1 = p2;
+    }
+
+  /* border check */
+  if (point_on_border (points, n_points, p))
+    return TRUE;
+
+  return (counter % 2 != 0);
+}
+
+/* check if the point p lies on the polygon "points"
+ */
+static gboolean
+point_on_border (const GimpVector2 *points,
+                 gint               n_points,
+                 GimpVector2        p)
+{
+  gint i;
+
+  for (i = 0; i <= n_points; i++)
+    {
+      GimpVector2   a  = points[i       % n_points];
+      GimpVector2   b  = points[(i + 1) % n_points];
+      gdouble a1 = (b.y - a.y);
+      gdouble b1 = (a.x - b.x);
+      gdouble c1 = a1 * a.x + b1 * a.y;
+      gdouble c2 = a1 * p.x + b1 * p.y;
+
+      if (ABS (c1 - c2) < EPSILON &&
+          MIN (a.x, b.x) <= p.x   &&
+          MAX (a.x, b.x) >= p.x   &&
+          MIN (a.y, b.y) <= p.y   &&
+          MAX (a.y, b.y) >= p.y)
+        return TRUE;
+    }
+
+  return FALSE;
+}
+
+/* calculate the intersection point of the line a-b with the line c-d
+ * and write it to i, if existing.
+ */
+static gboolean
+intersect (GimpVector2  a,
+           GimpVector2  b,
+           GimpVector2  c,
+           GimpVector2  d,
+           GimpVector2 *i)
+{
+  gdouble a1  = (b.y - a.y);
+  gdouble b1  = (a.x - b.x);
+  gdouble c1  = a1 * a.x + b1 * a.y;
+
+  gdouble a2  = (d.y - c.y);
+  gdouble b2  = (c.x - d.x);
+  gdouble c2  = a2 * c.x + b2 * c.y;
+  gdouble det = a1 * b2 - a2 * b1;
+
+  if (det == 0)
+    return FALSE;
+
+  i->x = (b2 * c1 - b1 * c2) / det;
+  i->y = (a1 * c2 - a2 * c1) / det;
+
+  return TRUE;
+}
+
+/* calculate the intersection point of the line a-b with the vertical line
+ * through c and write it to i, if existing.
+ */
+static gboolean
+intersect_x (GimpVector2  a,
+             GimpVector2  b,
+             GimpVector2  c,
+             GimpVector2 *i)
+{
+  GimpVector2   d = c;
+  d.y += 1;
+
+  return intersect(a,b,c,d,i);
+}
+
+/* calculate the intersection point of the line a-b with the horizontal line
+ * through c and write it to i, if existing.
+ */
+static gboolean
+intersect_y (GimpVector2  a,
+             GimpVector2  b,
+             GimpVector2  c,
+             GimpVector2 *i)
+{
+  GimpVector2   d = c;
+  d.x += 1;
+
+  return intersect(a,b,c,d,i);
+}
+
+/* this takes the smallest ortho-aligned (the sides of the rectangle are
+ * parallel to the x- and y-axis) rectangle fitting around the points a to d,
+ * checks if the whole rectangle is inside the polygon described by points and
+ * writes it to r if the area is bigger than the rectangle already stored in r.
+ */
+static void
+add_rectangle (const GimpVector2 *points,
+               gint               n_points,
+               Rectangle         *r,
+               GimpVector2        a,
+               GimpVector2        b,
+               GimpVector2        c,
+               GimpVector2        d)
+{
+  gdouble width;
+  gdouble height;
+  gdouble minx, maxx;
+  gdouble miny, maxy;
+
+  /* get the orthoaligned (the sides of the rectangle are parallel to the x-
+   * and y-axis) rectangle surrounding the points a to d.
+   */
+  minx = MIN4 (a.x, b.x, c.x, d.x);
+  maxx = MAX4 (a.x, b.x, c.x, d.x);
+  miny = MIN4 (a.y, b.y, c.y, d.y);
+  maxy = MAX4 (a.y, b.y, c.y, d.y);
+
+  a.x = minx;
+  a.y = miny;
+
+  b.x = maxx;
+  b.y = miny;
+
+  c.x = maxx;
+  c.y = maxy;
+
+  d.x = minx;
+  d.y = maxy;
+
+  width  =  maxx - minx;
+  height =  maxy - miny;
+
+  /* check if this rectangle is inside the polygon "points" */
+  if (in_poly (points, n_points, a) &&
+      in_poly (points, n_points, b) &&
+      in_poly (points, n_points, c) &&
+      in_poly (points, n_points, d))
+    {
+      gdouble area = width * height;
+
+      /* check if the new rectangle is larger (in terms of area)
+       * than the currently stored rectangle in r, if yes store
+       * new rectangle to r
+       */
+      if (r->area <= area)
+        {
+          r->a.x = a.x;
+          r->a.y = a.y;
+
+          r->b.x = b.x;
+          r->b.y = b.y;
+
+          r->c.x = c.x;
+          r->c.y = c.y;
+
+          r->d.x = d.x;
+          r->d.y = d.y;
+
+          r->area = area;
+        }
+    }
+}
diff --git a/app/core/gimp-transform-resize.h b/app/core/gimp-transform-resize.h
new file mode 100644
index 0000000..4ebb53f
--- /dev/null
+++ b/app/core/gimp-transform-resize.h
@@ -0,0 +1,34 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-2001 Spencer Kimball, Peter Mattis, and others
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_TRANSFORM_RESIZE_H__
+#define __GIMP_TRANSFORM_RESIZE_H__
+
+
+gboolean   gimp_transform_resize_boundary (const GimpMatrix3   *inv,
+                                           GimpTransformResize  resize,
+                                           gdouble              u1,
+                                           gdouble              v1,
+                                           gdouble              u2,
+                                           gdouble              v2,
+                                           gint                *x1,
+                                           gint                *y1,
+                                           gint                *x2,
+                                           gint                *y2);
+
+
+#endif  /*  __GIMP_TRANSFORM_RESIZE_H__  */
diff --git a/app/core/gimp-transform-utils.c b/app/core/gimp-transform-utils.c
new file mode 100644
index 0000000..555ff09
--- /dev/null
+++ b/app/core/gimp-transform-utils.c
@@ -0,0 +1,1211 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-2001 Spencer Kimball, Peter Mattis, and others
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <glib-object.h>
+
+#include "libgimpmath/gimpmath.h"
+
+#include "core-types.h"
+
+#include "gimp-transform-utils.h"
+#include "gimpcoords.h"
+#include "gimpcoords-interpolate.h"
+
+
+#define EPSILON 1e-6
+
+
+void
+gimp_transform_get_rotate_center (gint      x,
+                                  gint      y,
+                                  gint      width,
+                                  gint      height,
+                                  gboolean  auto_center,
+                                  gdouble  *center_x,
+                                  gdouble  *center_y)
+{
+  g_return_if_fail (center_x != NULL);
+  g_return_if_fail (center_y != NULL);
+
+  if (auto_center)
+    {
+      *center_x = (gdouble) x + (gdouble) width  / 2.0;
+      *center_y = (gdouble) y + (gdouble) height / 2.0;
+    }
+}
+
+void
+gimp_transform_get_flip_axis (gint                 x,
+                              gint                 y,
+                              gint                 width,
+                              gint                 height,
+                              GimpOrientationType  flip_type,
+                              gboolean             auto_center,
+                              gdouble             *axis)
+{
+  g_return_if_fail (axis != NULL);
+
+  if (auto_center)
+    {
+      switch (flip_type)
+        {
+        case GIMP_ORIENTATION_HORIZONTAL:
+          *axis = ((gdouble) x + (gdouble) width / 2.0);
+          break;
+
+        case GIMP_ORIENTATION_VERTICAL:
+          *axis = ((gdouble) y + (gdouble) height / 2.0);
+          break;
+
+        default:
+          g_return_if_reached ();
+          break;
+        }
+    }
+}
+
+void
+gimp_transform_matrix_flip (GimpMatrix3         *matrix,
+                            GimpOrientationType  flip_type,
+                            gdouble              axis)
+{
+  g_return_if_fail (matrix != NULL);
+
+  switch (flip_type)
+    {
+    case GIMP_ORIENTATION_HORIZONTAL:
+      gimp_matrix3_translate (matrix, - axis, 0.0);
+      gimp_matrix3_scale (matrix, -1.0, 1.0);
+      gimp_matrix3_translate (matrix, axis, 0.0);
+      break;
+
+    case GIMP_ORIENTATION_VERTICAL:
+      gimp_matrix3_translate (matrix, 0.0, - axis);
+      gimp_matrix3_scale (matrix, 1.0, -1.0);
+      gimp_matrix3_translate (matrix, 0.0, axis);
+      break;
+
+    case GIMP_ORIENTATION_UNKNOWN:
+      break;
+    }
+}
+
+void
+gimp_transform_matrix_flip_free (GimpMatrix3 *matrix,
+                                 gdouble      x1,
+                                 gdouble      y1,
+                                 gdouble      x2,
+                                 gdouble      y2)
+{
+  gdouble angle;
+
+  g_return_if_fail (matrix != NULL);
+
+  angle = atan2  (y2 - y1, x2 - x1);
+
+  gimp_matrix3_identity  (matrix);
+  gimp_matrix3_translate (matrix, -x1, -y1);
+  gimp_matrix3_rotate    (matrix, -angle);
+  gimp_matrix3_scale     (matrix, 1.0, -1.0);
+  gimp_matrix3_rotate    (matrix, angle);
+  gimp_matrix3_translate (matrix, x1, y1);
+}
+
+void
+gimp_transform_matrix_rotate (GimpMatrix3         *matrix,
+                              GimpRotationType     rotate_type,
+                              gdouble              center_x,
+                              gdouble              center_y)
+{
+  gdouble angle = 0;
+
+  switch (rotate_type)
+    {
+    case GIMP_ROTATE_90:
+      angle = G_PI_2;
+      break;
+    case GIMP_ROTATE_180:
+      angle = G_PI;
+      break;
+    case GIMP_ROTATE_270:
+      angle = - G_PI_2;
+      break;
+    }
+
+  gimp_transform_matrix_rotate_center (matrix, center_x, center_y, angle);
+}
+
+void
+gimp_transform_matrix_rotate_rect (GimpMatrix3 *matrix,
+                                   gint         x,
+                                   gint         y,
+                                   gint         width,
+                                   gint         height,
+                                   gdouble      angle)
+{
+  gdouble center_x;
+  gdouble center_y;
+
+  g_return_if_fail (matrix != NULL);
+
+  center_x = (gdouble) x + (gdouble) width  / 2.0;
+  center_y = (gdouble) y + (gdouble) height / 2.0;
+
+  gimp_matrix3_translate (matrix, -center_x, -center_y);
+  gimp_matrix3_rotate    (matrix, angle);
+  gimp_matrix3_translate (matrix, +center_x, +center_y);
+}
+
+void
+gimp_transform_matrix_rotate_center (GimpMatrix3 *matrix,
+                                     gdouble      center_x,
+                                     gdouble      center_y,
+                                     gdouble      angle)
+{
+  g_return_if_fail (matrix != NULL);
+
+  gimp_matrix3_translate (matrix, -center_x, -center_y);
+  gimp_matrix3_rotate    (matrix, angle);
+  gimp_matrix3_translate (matrix, +center_x, +center_y);
+}
+
+void
+gimp_transform_matrix_scale (GimpMatrix3 *matrix,
+                             gint         x,
+                             gint         y,
+                             gint         width,
+                             gint         height,
+                             gdouble      t_x,
+                             gdouble      t_y,
+                             gdouble      t_width,
+                             gdouble      t_height)
+{
+  gdouble scale_x = 1.0;
+  gdouble scale_y = 1.0;
+
+  g_return_if_fail (matrix != NULL);
+
+  if (width > 0)
+    scale_x = t_width / (gdouble) width;
+
+  if (height > 0)
+    scale_y = t_height / (gdouble) height;
+
+  gimp_matrix3_identity  (matrix);
+  gimp_matrix3_translate (matrix, -x, -y);
+  gimp_matrix3_scale     (matrix, scale_x, scale_y);
+  gimp_matrix3_translate (matrix, t_x, t_y);
+}
+
+void
+gimp_transform_matrix_shear (GimpMatrix3         *matrix,
+                             gint                 x,
+                             gint                 y,
+                             gint                 width,
+                             gint                 height,
+                             GimpOrientationType  orientation,
+                             gdouble              amount)
+{
+  gdouble center_x;
+  gdouble center_y;
+
+  g_return_if_fail (matrix != NULL);
+
+  if (width == 0)
+    width = 1;
+
+  if (height == 0)
+    height = 1;
+
+  center_x = (gdouble) x + (gdouble) width  / 2.0;
+  center_y = (gdouble) y + (gdouble) height / 2.0;
+
+  gimp_matrix3_identity  (matrix);
+  gimp_matrix3_translate (matrix, -center_x, -center_y);
+
+  if (orientation == GIMP_ORIENTATION_HORIZONTAL)
+    gimp_matrix3_xshear (matrix, amount / height);
+  else
+    gimp_matrix3_yshear (matrix, amount / width);
+
+  gimp_matrix3_translate (matrix, +center_x, +center_y);
+}
+
+void
+gimp_transform_matrix_perspective (GimpMatrix3 *matrix,
+                                   gint         x,
+                                   gint         y,
+                                   gint         width,
+                                   gint         height,
+                                   gdouble      t_x1,
+                                   gdouble      t_y1,
+                                   gdouble      t_x2,
+                                   gdouble      t_y2,
+                                   gdouble      t_x3,
+                                   gdouble      t_y3,
+                                   gdouble      t_x4,
+                                   gdouble      t_y4)
+{
+  GimpMatrix3 trafo;
+  gdouble     scalex;
+  gdouble     scaley;
+
+  g_return_if_fail (matrix != NULL);
+
+  scalex = scaley = 1.0;
+
+  if (width > 0)
+    scalex = 1.0 / (gdouble) width;
+
+  if (height > 0)
+    scaley = 1.0 / (gdouble) height;
+
+  gimp_matrix3_translate (matrix, -x, -y);
+  gimp_matrix3_scale     (matrix, scalex, scaley);
+
+  /* Determine the perspective transform that maps from
+   * the unit cube to the transformed coordinates
+   */
+  {
+    gdouble dx1, dx2, dx3, dy1, dy2, dy3;
+
+    dx1 = t_x2 - t_x4;
+    dx2 = t_x3 - t_x4;
+    dx3 = t_x1 - t_x2 + t_x4 - t_x3;
+
+    dy1 = t_y2 - t_y4;
+    dy2 = t_y3 - t_y4;
+    dy3 = t_y1 - t_y2 + t_y4 - t_y3;
+
+    /*  Is the mapping affine?  */
+    if ((dx3 == 0.0) && (dy3 == 0.0))
+      {
+        trafo.coeff[0][0] = t_x2 - t_x1;
+        trafo.coeff[0][1] = t_x4 - t_x2;
+        trafo.coeff[0][2] = t_x1;
+        trafo.coeff[1][0] = t_y2 - t_y1;
+        trafo.coeff[1][1] = t_y4 - t_y2;
+        trafo.coeff[1][2] = t_y1;
+        trafo.coeff[2][0] = 0.0;
+        trafo.coeff[2][1] = 0.0;
+      }
+    else
+      {
+        gdouble det1, det2;
+
+        det1 = dx3 * dy2 - dy3 * dx2;
+        det2 = dx1 * dy2 - dy1 * dx2;
+
+        trafo.coeff[2][0] = (det2 == 0.0) ? 1.0 : det1 / det2;
+
+        det1 = dx1 * dy3 - dy1 * dx3;
+
+        trafo.coeff[2][1] = (det2 == 0.0) ? 1.0 : det1 / det2;
+
+        trafo.coeff[0][0] = t_x2 - t_x1 + trafo.coeff[2][0] * t_x2;
+        trafo.coeff[0][1] = t_x3 - t_x1 + trafo.coeff[2][1] * t_x3;
+        trafo.coeff[0][2] = t_x1;
+
+        trafo.coeff[1][0] = t_y2 - t_y1 + trafo.coeff[2][0] * t_y2;
+        trafo.coeff[1][1] = t_y3 - t_y1 + trafo.coeff[2][1] * t_y3;
+        trafo.coeff[1][2] = t_y1;
+      }
+
+    trafo.coeff[2][2] = 1.0;
+  }
+
+  gimp_matrix3_mult (&trafo, matrix);
+}
+
+/* modified gaussian algorithm
+ * solves a system of linear equations
+ *
+ * Example:
+ * 1x + 2y + 4z = 25
+ * 2x + 1y      = 4
+ * 3x + 5y + 2z = 23
+ * Solution: x=1, y=2, z=5
+ *
+ * Input:
+ * matrix = { 1,2,4,25,2,1,0,4,3,5,2,23 }
+ * s = 3 (Number of variables)
+ * Output:
+ * return value == TRUE (TRUE, if there is a single unique solution)
+ * solution == { 1,2,5 } (if the return value is FALSE, the content
+ * of solution is of no use)
+ */
+static gboolean
+mod_gauss (gdouble matrix[],
+           gdouble solution[],
+           gint    s)
+{
+  gint    p[s]; /* row permutation */
+  gint    i, j, r, temp;
+  gdouble q;
+  gint    t = s + 1;
+
+  for (i = 0; i < s; i++)
+    {
+      p[i] = i;
+    }
+
+  for (r = 0; r < s; r++)
+    {
+      /* make sure that (r,r) is not 0 */
+      if (fabs (matrix[p[r] * t + r]) <= EPSILON)
+        {
+          /* we need to permutate rows */
+          for (i = r + 1; i <= s; i++)
+            {
+              if (i == s)
+                {
+                  /* if this happens, the linear system has zero or
+                   * more than one solutions.
+                   */
+                  return FALSE;
+                }
+
+              if (fabs (matrix[p[i] * t + r]) > EPSILON)
+                break;
+            }
+
+          temp = p[r];
+          p[r] = p[i];
+          p[i] = temp;
+        }
+
+      /* make (r,r) == 1 */
+      q = 1.0 / matrix[p[r] * t + r];
+      matrix[p[r] * t + r] = 1.0;
+
+      for (j = r + 1; j < t; j++)
+        {
+          matrix[p[r] * t + j] *= q;
+        }
+
+      /* make that all entries in column r are 0 (except (r,r)) */
+      for (i = 0; i < s; i++)
+        {
+          if (i == r)
+            continue;
+
+          for (j = r + 1; j < t ; j++)
+            {
+              matrix[p[i] * t + j] -= matrix[p[r] * t + j] * matrix[p[i] * t + r];
+            }
+
+          /* we don't need to execute the following line
+           * since we won't access this element again:
+           *
+           * matrix[p[i] * t + r] = 0.0;
+           */
+        }
+    }
+
+  for (i = 0; i < s; i++)
+    {
+      solution[i] = matrix[p[i] * t + s];
+    }
+
+  return TRUE;
+}
+
+/* multiplies 'matrix' by the matrix that transforms a set of 4 'input_points'
+ * to corresponding 'output_points', if such matrix exists, and is valid (i.e.,
+ * keeps the output points in front of the camera).
+ *
+ * returns TRUE if successful.
+ */
+gboolean
+gimp_transform_matrix_generic (GimpMatrix3       *matrix,
+                               const GimpVector2  input_points[4],
+                               const GimpVector2  output_points[4])
+{
+  GimpMatrix3 trafo;
+  gdouble     coeff[8 * 9];
+  gboolean    negative = -1;
+  gint        i;
+  gboolean    result   = TRUE;
+
+  g_return_val_if_fail (matrix != NULL, FALSE);
+  g_return_val_if_fail (input_points != NULL, FALSE);
+  g_return_val_if_fail (output_points != NULL, FALSE);
+
+  /* find the matrix that transforms 'input_points' to 'output_points', whose
+   * (3, 3) coeffcient is 1, by solving a system of linear equations whose
+   * solution is the remaining 8 coefficients.
+   */
+  for (i = 0; i < 4; i++)
+    {
+      coeff[i * 9 + 0] = input_points[i].x;
+      coeff[i * 9 + 1] = input_points[i].y;
+      coeff[i * 9 + 2] = 1.0;
+      coeff[i * 9 + 3] = 0.0;
+      coeff[i * 9 + 4] = 0.0;
+      coeff[i * 9 + 5] = 0.0;
+      coeff[i * 9 + 6] = -input_points[i].x * output_points[i].x;
+      coeff[i * 9 + 7] = -input_points[i].y * output_points[i].x;
+      coeff[i * 9 + 8] =                      output_points[i].x;
+
+      coeff[(i + 4) * 9 + 0] = 0.0;
+      coeff[(i + 4) * 9 + 1] = 0.0;
+      coeff[(i + 4) * 9 + 2] = 0.0;
+      coeff[(i + 4) * 9 + 3] = input_points[i].x;
+      coeff[(i + 4) * 9 + 4] = input_points[i].y;
+      coeff[(i + 4) * 9 + 5] = 1.0;
+      coeff[(i + 4) * 9 + 6] = -input_points[i].x * output_points[i].y;
+      coeff[(i + 4) * 9 + 7] = -input_points[i].y * output_points[i].y;
+      coeff[(i + 4) * 9 + 8] =                      output_points[i].y;
+    }
+
+  /* if there is no solution, bail */
+  if (! mod_gauss (coeff, (gdouble *) trafo.coeff, 8))
+    return FALSE;
+
+  trafo.coeff[2][2] = 1.0;
+
+  /* make sure that none of the input points maps to a point at infinity, and
+   * that all output points are on the same side of the camera.
+   */
+  for (i = 0; i < 4; i++)
+    {
+      gdouble  w;
+      gboolean neg;
+
+      w = trafo.coeff[2][0] * input_points[i].x +
+          trafo.coeff[2][1] * input_points[i].y +
+          trafo.coeff[2][2];
+
+      if (fabs (w) <= EPSILON)
+        result = FALSE;
+
+      neg = (w < 0.0);
+
+      if (negative < 0)
+        {
+          negative = neg;
+        }
+      else if (neg != negative)
+        {
+          result = FALSE;
+          break;
+        }
+    }
+
+  /* if the output points are all behind the camera, negate the matrix, which
+   * would map the input points to the corresponding points in front of the
+   * camera.
+   */
+  if (negative > 0)
+    {
+      gint r;
+      gint c;
+
+      for (r = 0; r < 3; r++)
+        {
+          for (c = 0; c < 3; c++)
+            {
+              trafo.coeff[r][c] = -trafo.coeff[r][c];
+            }
+        }
+    }
+
+  /* append the transformation to 'matrix' */
+  gimp_matrix3_mult (&trafo, matrix);
+
+  return result;
+}
+
+gboolean
+gimp_transform_polygon_is_convex (gdouble x1,
+                                  gdouble y1,
+                                  gdouble x2,
+                                  gdouble y2,
+                                  gdouble x3,
+                                  gdouble y3,
+                                  gdouble x4,
+                                  gdouble y4)
+{
+  gdouble z1, z2, z3, z4;
+
+  /* We test if the transformed polygon is convex.  if z1 and z2 have
+   * the same sign as well as z3 and z4 the polygon is convex.
+   */
+  z1 = ((x2 - x1) * (y4 - y1) -
+        (x4 - x1) * (y2 - y1));
+  z2 = ((x4 - x1) * (y3 - y1) -
+        (x3 - x1) * (y4 - y1));
+  z3 = ((x4 - x2) * (y3 - y2) -
+        (x3 - x2) * (y4 - y2));
+  z4 = ((x3 - x2) * (y1 - y2) -
+        (x1 - x2) * (y3 - y2));
+
+  return (z1 * z2 > 0) && (z3 * z4 > 0);
+}
+
+/* transforms the polygon or polyline, whose vertices are given by 'vertices',
+ * by 'matrix', performing clipping by the near plane.  'closed' indicates
+ * whether the vertices represent a polygon ('closed == TRUE') or a polyline
+ * ('closed == FALSE').
+ *
+ * returns the transformed vertices in 't_vertices', and their count in
+ * 'n_t_vertices'.  the minimal possible number of transformed vertices is 0,
+ * which happens when the entire input is clipped.  in general, the maximal
+ * possible number of transformed vertices is '3 * n_vertices / 2' (rounded
+ * down), however, for convex polygons the number is 'n_vertices + 1', and for
+ * a single line segment ('n_vertices == 2' and 'closed == FALSE') the number
+ * is 2.
+ *
+ * 't_vertices' may not alias 'vertices', except when transforming a single
+ * line segment.
+ */
+void
+gimp_transform_polygon (const GimpMatrix3 *matrix,
+                        const GimpVector2 *vertices,
+                        gint               n_vertices,
+                        gboolean           closed,
+                        GimpVector2       *t_vertices,
+                        gint              *n_t_vertices)
+{
+  GimpVector3 curr;
+  gboolean    curr_visible;
+  gint        i;
+
+  g_return_if_fail (matrix != NULL);
+  g_return_if_fail (vertices != NULL);
+  g_return_if_fail (n_vertices >= 0);
+  g_return_if_fail (t_vertices != NULL);
+  g_return_if_fail (n_t_vertices != NULL);
+
+  *n_t_vertices = 0;
+
+  if (n_vertices == 0)
+    return;
+
+  curr.x = matrix->coeff[0][0] * vertices[0].x +
+           matrix->coeff[0][1] * vertices[0].y +
+           matrix->coeff[0][2];
+  curr.y = matrix->coeff[1][0] * vertices[0].x +
+           matrix->coeff[1][1] * vertices[0].y +
+           matrix->coeff[1][2];
+  curr.z = matrix->coeff[2][0] * vertices[0].x +
+           matrix->coeff[2][1] * vertices[0].y +
+           matrix->coeff[2][2];
+
+  curr_visible = (curr.z >= GIMP_TRANSFORM_NEAR_Z);
+
+  for (i = 0; i < n_vertices; i++)
+    {
+      if (curr_visible)
+        {
+          t_vertices[(*n_t_vertices)++] = (GimpVector2) { curr.x / curr.z,
+                                                          curr.y / curr.z };
+        }
+
+      if (i < n_vertices - 1 || closed)
+        {
+          GimpVector3 next;
+          gboolean    next_visible;
+          gint        j = (i + 1) % n_vertices;
+
+          next.x = matrix->coeff[0][0] * vertices[j].x +
+                   matrix->coeff[0][1] * vertices[j].y +
+                   matrix->coeff[0][2];
+          next.y = matrix->coeff[1][0] * vertices[j].x +
+                   matrix->coeff[1][1] * vertices[j].y +
+                   matrix->coeff[1][2];
+          next.z = matrix->coeff[2][0] * vertices[j].x +
+                   matrix->coeff[2][1] * vertices[j].y +
+                   matrix->coeff[2][2];
+
+          next_visible = (next.z >= GIMP_TRANSFORM_NEAR_Z);
+
+          if (next_visible != curr_visible)
+            {
+              gdouble ratio = (curr.z - GIMP_TRANSFORM_NEAR_Z) / (curr.z - next.z);
+
+              t_vertices[(*n_t_vertices)++] =
+                (GimpVector2) { (curr.x + (next.x - curr.x) * ratio) / GIMP_TRANSFORM_NEAR_Z,
+                                (curr.y + (next.y - curr.y) * ratio) / GIMP_TRANSFORM_NEAR_Z };
+            }
+
+          curr         = next;
+          curr_visible = next_visible;
+        }
+    }
+}
+
+/* same as gimp_transform_polygon(), but using GimpCoords as the vertex type,
+ * instead of GimpVector2.
+ */
+void
+gimp_transform_polygon_coords (const GimpMatrix3 *matrix,
+                               const GimpCoords  *vertices,
+                               gint               n_vertices,
+                               gboolean           closed,
+                               GimpCoords        *t_vertices,
+                               gint              *n_t_vertices)
+{
+  GimpVector3 curr;
+  gboolean    curr_visible;
+  gint        i;
+
+  g_return_if_fail (matrix != NULL);
+  g_return_if_fail (vertices != NULL);
+  g_return_if_fail (n_vertices >= 0);
+  g_return_if_fail (t_vertices != NULL);
+  g_return_if_fail (n_t_vertices != NULL);
+
+  *n_t_vertices = 0;
+
+  if (n_vertices == 0)
+    return;
+
+  curr.x = matrix->coeff[0][0] * vertices[0].x +
+           matrix->coeff[0][1] * vertices[0].y +
+           matrix->coeff[0][2];
+  curr.y = matrix->coeff[1][0] * vertices[0].x +
+           matrix->coeff[1][1] * vertices[0].y +
+           matrix->coeff[1][2];
+  curr.z = matrix->coeff[2][0] * vertices[0].x +
+           matrix->coeff[2][1] * vertices[0].y +
+           matrix->coeff[2][2];
+
+  curr_visible = (curr.z >= GIMP_TRANSFORM_NEAR_Z);
+
+  for (i = 0; i < n_vertices; i++)
+    {
+      if (curr_visible)
+        {
+          t_vertices[*n_t_vertices]   = vertices[i];
+          t_vertices[*n_t_vertices].x = curr.x / curr.z;
+          t_vertices[*n_t_vertices].y = curr.y / curr.z;
+
+          (*n_t_vertices)++;
+        }
+
+      if (i < n_vertices - 1 || closed)
+        {
+          GimpVector3 next;
+          gboolean    next_visible;
+          gint        j = (i + 1) % n_vertices;
+
+          next.x = matrix->coeff[0][0] * vertices[j].x +
+                   matrix->coeff[0][1] * vertices[j].y +
+                   matrix->coeff[0][2];
+          next.y = matrix->coeff[1][0] * vertices[j].x +
+                   matrix->coeff[1][1] * vertices[j].y +
+                   matrix->coeff[1][2];
+          next.z = matrix->coeff[2][0] * vertices[j].x +
+                   matrix->coeff[2][1] * vertices[j].y +
+                   matrix->coeff[2][2];
+
+          next_visible = (next.z >= GIMP_TRANSFORM_NEAR_Z);
+
+          if (next_visible != curr_visible)
+            {
+              gdouble ratio = (curr.z - GIMP_TRANSFORM_NEAR_Z) / (curr.z - next.z);
+
+              gimp_coords_mix (1.0 - ratio, &vertices[i],
+                                     ratio, &vertices[j],
+                                            &t_vertices[*n_t_vertices]);
+
+              t_vertices[*n_t_vertices].x = (curr.x + (next.x - curr.x) * ratio) /
+                                             GIMP_TRANSFORM_NEAR_Z;
+              t_vertices[*n_t_vertices].y = (curr.y + (next.y - curr.y) * ratio) /
+                                             GIMP_TRANSFORM_NEAR_Z;
+
+              (*n_t_vertices)++;
+            }
+
+          curr         = next;
+          curr_visible = next_visible;
+        }
+    }
+}
+
+/* returns the value of the polynomial 'poly', of degree 'degree', at 'x'.  the
+ * coefficients of 'poly' should be specified in descending-degree order.
+ */
+static gdouble
+polynomial_eval (const gdouble *poly,
+                 gint           degree,
+                 gdouble        x)
+{
+  gdouble y = poly[0];
+  gint    i;
+
+  for (i = 1; i <= degree; i++)
+    y = y * x + poly[i];
+
+  return y;
+}
+
+/* derives the polynomial 'poly', of degree 'degree'.
+ *
+ * returns the derivative in 'result'.
+ */
+static void
+polynomial_derive (const gdouble *poly,
+                   gint           degree,
+                   gdouble       *result)
+{
+  while (degree)
+    *result++ = *poly++ * degree--;
+}
+
+/* finds the real odd-multiplicity root of the polynomial 'poly', of degree
+ * 'degree', inside the range '(x1, x2)'.
+ *
+ * returns TRUE if such a root exists, and stores its value in '*root'.
+ *
+ * 'poly' shall be monotonic in the range '(x1, x2)'.
+ */
+static gboolean
+polynomial_odd_root (const gdouble *poly,
+                     gint           degree,
+                     gdouble        x1,
+                     gdouble        x2,
+                     gdouble       *root)
+{
+  gdouble y1;
+  gdouble y2;
+  gint    i;
+
+  y1 = polynomial_eval (poly, degree, x1);
+  y2 = polynomial_eval (poly, degree, x2);
+
+  if (y1 * y2 > -EPSILON)
+    {
+      /* the two endpoints have the same sign, or one of them is zero.  there's
+       * no root inside the range.
+       */
+      return FALSE;
+    }
+  else if (y1 > 0.0)
+    {
+      gdouble t;
+
+      /* if the first endpoint is positive, swap the endpoints, so that the
+       * first endpoint is always negative, and the second endpoint is always
+       * positive.
+       */
+
+      t  = x1;
+      x1 = x2;
+      x2 = t;
+    }
+
+  /* approximate the root using binary search */
+  for (i = 0; i < 53; i++)
+    {
+      gdouble x = (x1 + x2) / 2.0;
+      gdouble y = polynomial_eval (poly, degree, x);
+
+      if (y > 0.0)
+        x2 = x;
+      else
+        x1 = x;
+    }
+
+  *root = (x1 + x2) / 2.0;
+
+  return TRUE;
+}
+
+/* finds the real odd-multiplicity roots of the polynomial 'poly', of degree
+ * 'degree', inside the range '(x1, x2)'.
+ *
+ * returns the roots in 'roots', in ascending order, and their count in
+ * 'n_roots'.
+ */
+static void
+polynomial_odd_roots (const gdouble *poly,
+                      gint           degree,
+                      gdouble        x1,
+                      gdouble        x2,
+                      gdouble       *roots,
+                      gint          *n_roots)
+{
+  *n_roots = 0;
+
+  /* find the real degree of the polynomial (skip any leading coefficients that
+   * are 0)
+   */
+  for (; degree && fabs (*poly) < EPSILON; poly++, degree--);
+
+  #define ADD_ROOT(root) \
+    do \
+      { \
+        gdouble r = (root); \
+        \
+        if (r > x1 && r < x2) \
+          roots[(*n_roots)++] = r; \
+      } \
+    while (FALSE)
+
+  switch (degree)
+    {
+    /* constant case */
+    case 0:
+      break;
+
+    /* linear case */
+    case 1:
+      ADD_ROOT (-poly[1] / poly[0]);
+      break;
+
+    /* quadratic case */
+    case 2:
+      {
+        gdouble s = SQR (poly[1]) - 4 * poly[0] * poly[2];
+
+        if (s > EPSILON)
+          {
+            s = sqrt (s);
+
+            if (poly[0] < 0.0)
+              s = -s;
+
+            ADD_ROOT ((-poly[1] - s) / (2.0 * poly[0]));
+            ADD_ROOT ((-poly[1] + s) / (2.0 * poly[0]));
+          }
+
+        break;
+      }
+
+    /* general case */
+    default:
+      {
+        gdouble deriv[degree];
+        gdouble deriv_roots[degree - 1];
+        gint    n_deriv_roots;
+        gdouble a;
+        gdouble b;
+        gint    i;
+
+        /* find the odd roots of the derivative, i.e., the local extrema of the
+         * polynomial
+         */
+        polynomial_derive (poly, degree, deriv);
+        polynomial_odd_roots (deriv, degree - 1, x1, x2,
+                              deriv_roots, &n_deriv_roots);
+
+        /* search for roots between each consecutive pair of extrema, including
+         * the endpoints
+         */
+        a = x1;
+
+        for (i = 0; i <= n_deriv_roots; i++)
+          {
+            if (i < n_deriv_roots)
+              b = deriv_roots[i];
+            else
+              b = x2;
+
+            *n_roots += polynomial_odd_root (poly, degree, a, b,
+                                             &roots[*n_roots]);
+
+            a = b;
+          }
+
+        break;
+      }
+    }
+
+  #undef ADD_ROOT
+}
+
+/* clips the cubic bezier segment, defined by the four control points 'bezier',
+ * to the halfplane 'ax + by + c >= 0'.
+ *
+ * returns the clipped set of bezier segments in 'c_bezier', and their count in
+ * 'n_c_bezier'.  the minimal possible number of clipped segments is 0, which
+ * happens when the entire segment is clipped.  the maximal possible number of
+ * clipped segments is 2.
+ *
+ * if the first clipped segment is an initial segment of 'bezier', sets
+ * '*start_in' to TRUE, otherwise to FALSE.  if the last clipped segment is a
+ * final segment of 'bezier', sets '*end_in' to TRUE, otherwise to FALSE.
+ *
+ * 'c_bezier' may not alias 'bezier'.
+ */
+static void
+clip_bezier (const GimpCoords  bezier[4],
+             gdouble           a,
+             gdouble           b,
+             gdouble           c,
+             GimpCoords        c_bezier[2][4],
+             gint             *n_c_bezier,
+             gboolean         *start_in,
+             gboolean         *end_in)
+{
+  gdouble dot[4];
+  gdouble poly[4];
+  gdouble roots[5];
+  gint    n_roots;
+  gint    n_positive;
+  gint    i;
+
+  n_positive = 0;
+
+  for (i = 0; i < 4; i++)
+    {
+      dot[i] = a * bezier[i].x + b * bezier[i].y + c;
+
+      n_positive += (dot[i] >= 0.0);
+    }
+
+  if (n_positive == 0)
+    {
+      /* all points are out -- the entire segment is out */
+
+      *n_c_bezier = 0;
+      *start_in   = FALSE;
+      *end_in     = FALSE;
+
+      return;
+    }
+  else if (n_positive == 4)
+    {
+      /* all points are in -- the entire segment is in */
+
+      memcpy (c_bezier[0], bezier, sizeof (GimpCoords[4]));
+
+      *n_c_bezier = 1;
+      *start_in   = TRUE;
+      *end_in     = TRUE;
+
+      return;
+    }
+
+  /* find the points of intersection of the segment with the 'ax + by + c = 0'
+   * line
+   */
+  poly[0] = dot[3] - 3.0 * dot[2] + 3.0 * dot[1] - dot[0];
+  poly[1] = 3.0 * (dot[2] - 2.0 * dot[1] + dot[0]);
+  poly[2] = 3.0 * (dot[1] - dot[0]);
+  poly[3] = dot[0];
+
+  roots[0] = 0.0;
+  polynomial_odd_roots (poly, 3, 0.0, 1.0, roots + 1, &n_roots);
+  roots[++n_roots] = 1.0;
+
+  /* construct the list of segments that are inside the halfplane */
+  *n_c_bezier = 0;
+  *start_in   = (polynomial_eval (poly, 3, roots[1] / 2.0) > 0.0);
+  *end_in     = (*start_in + n_roots + 1) % 2;
+
+  for (i = ! *start_in; i < n_roots; i += 2)
+    {
+      gdouble t0 = roots[i];
+      gdouble t1 = roots[i + 1];
+
+      gimp_coords_interpolate_bezier_at (bezier, t0,
+                                         &c_bezier[*n_c_bezier][0],
+                                         &c_bezier[*n_c_bezier][1]);
+      gimp_coords_interpolate_bezier_at (bezier, t1,
+                                         &c_bezier[*n_c_bezier][3],
+                                         &c_bezier[*n_c_bezier][2]);
+
+      gimp_coords_mix (1.0,             &c_bezier[*n_c_bezier][0],
+                       (t1 - t0) / 3.0, &c_bezier[*n_c_bezier][1],
+                       &c_bezier[*n_c_bezier][1]);
+      gimp_coords_mix (1.0,             &c_bezier[*n_c_bezier][3],
+                       (t0 - t1) / 3.0, &c_bezier[*n_c_bezier][2],
+                       &c_bezier[*n_c_bezier][2]);
+
+      (*n_c_bezier)++;
+    }
+}
+
+/* transforms the cubic bezier segment, defined by the four control points
+ * 'bezier', by 'matrix', subdividing it as necessary to avoid diverging too
+ * much from the real transformed curve.  at most 'depth' subdivisions are
+ * performed.
+ *
+ * appends the transformed sequence of bezier segments to 't_beziers'.
+ *
+ * 'bezier' shall be fully clipped to the near plane.
+ */
+static void
+transform_bezier_coords (const GimpMatrix3 *matrix,
+                         const GimpCoords   bezier[4],
+                         GQueue            *t_beziers,
+                         gint               depth)
+{
+  GimpCoords *t_bezier;
+  gint        n;
+
+  /* check if we need to split the segment */
+  if (depth > 0)
+    {
+      GimpVector2 v[4];
+      GimpVector2 c[2];
+      GimpVector2 b;
+      gint        i;
+
+      for (i = 0; i < 4; i++)
+        v[i] = (GimpVector2) { bezier[i].x, bezier[i].y };
+
+      gimp_vector2_sub (&c[0], &v[1], &v[0]);
+      gimp_vector2_sub (&c[1], &v[2], &v[3]);
+
+      gimp_vector2_sub (&b, &v[3], &v[0]);
+      gimp_vector2_mul (&b, 1.0 / gimp_vector2_inner_product (&b, &b));
+
+      for (i = 0; i < 2; i++)
+        {
+          /* split the segment if one of the control points is too far from the
+           * line connecting the anchors
+           */
+          if (fabs (gimp_vector2_cross_product (&c[i], &b).x) > 0.5)
+            {
+              GimpCoords mid_position;
+              GimpCoords mid_velocity;
+              GimpCoords sub[4];
+
+              gimp_coords_interpolate_bezier_at (bezier, 0.5,
+                                                 &mid_position, &mid_velocity);
+
+              /* first half */
+              sub[0] = bezier[0];
+              sub[3] = mid_position;
+
+              gimp_coords_mix (0.5,        &sub[0],
+                               0.5,        &bezier[1],
+                                           &sub[1]);
+              gimp_coords_mix (1.0,        &sub[3],
+                               -1.0 / 6.0, &mid_velocity,
+                                           &sub[2]);
+
+              transform_bezier_coords (matrix, sub, t_beziers, depth - 1);
+
+              /* second half */
+              sub[0] = mid_position;
+              sub[3] = bezier[3];
+
+              gimp_coords_mix (1.0,        &sub[0],
+                               +1.0 / 6.0, &mid_velocity,
+                                           &sub[1]);
+              gimp_coords_mix (0.5,        &sub[3],
+                               0.5,        &bezier[2],
+                                           &sub[2]);
+
+              transform_bezier_coords (matrix, sub, t_beziers, depth - 1);
+
+              return;
+            }
+        }
+    }
+
+  /* transform the segment by transforming each of the individual points.  note
+   * that, for non-affine transforms, this is only an approximation of the real
+   * transformed curve, but due to subdivision it should be good enough.
+   */
+  t_bezier = g_new (GimpCoords, 4);
+
+  /* note that while the segments themselves are clipped to the near plane,
+   * their control points may still get transformed behind the camera.  we
+   * therefore clip the control points to the near plane as well, which is not
+   * too meaningful, but avoids erroneously transforming them behind the
+   * camera.
+   */
+  gimp_transform_polygon_coords (matrix, bezier, 2, FALSE,
+                                 t_bezier, &n);
+  gimp_transform_polygon_coords (matrix, bezier + 2, 2, FALSE,
+                                 t_bezier + 2, &n);
+
+  g_queue_push_tail (t_beziers, t_bezier);
+}
+
+/* transforms the cubic bezier segment, defined by the four control points
+ * 'bezier', by 'matrix', performing clipping by the near plane and subdividing
+ * as necessary.
+ *
+ * returns the transformed set of bezier-segment sequences in 't_beziers', as
+ * GQueues of GimpCoords[4] bezier-segments, and the number of sequences in
+ * 'n_t_beziers'.  the minimal possible number of transformed sequences is 0,
+ * which happens when the entire segment is clipped.  the maximal possible
+ * number of transformed sequences is 2.  each sequence has at least one
+ * segment.
+ *
+ * if the first transformed segment is an initial segment of 'bezier', sets
+ * '*start_in' to TRUE, otherwise to FALSE.  if the last transformed segment is
+ * a final segment of 'bezier', sets '*end_in' to TRUE, otherwise to FALSE.
+ */
+void
+gimp_transform_bezier_coords (const GimpMatrix3 *matrix,
+                              const GimpCoords   bezier[4],
+                              GQueue            *t_beziers[2],
+                              gint              *n_t_beziers,
+                              gboolean          *start_in,
+                              gboolean          *end_in)
+{
+  GimpCoords c_bezier[2][4];
+  gint       i;
+
+  g_return_if_fail (matrix != NULL);
+  g_return_if_fail (bezier != NULL);
+  g_return_if_fail (t_beziers != NULL);
+  g_return_if_fail (n_t_beziers != NULL);
+  g_return_if_fail (start_in != NULL);
+  g_return_if_fail (end_in != NULL);
+
+  /* if the matrix is affine, transform the easy way */
+  if (gimp_matrix3_is_affine (matrix))
+    {
+      GimpCoords *t_bezier;
+
+      t_beziers[0] = g_queue_new ();
+      *n_t_beziers = 1;
+
+      t_bezier = g_new (GimpCoords, 1);
+      g_queue_push_tail (t_beziers[0], t_bezier);
+
+      for (i = 0; i < 4; i++)
+        {
+          t_bezier[i] = bezier[i];
+
+          gimp_matrix3_transform_point (matrix,
+                                        bezier[i].x,    bezier[i].y,
+                                        &t_bezier[i].x, &t_bezier[i].y);
+        }
+
+      return;
+    }
+
+  /* clip the segment to the near plane */
+  clip_bezier (bezier,
+               matrix->coeff[2][0],
+               matrix->coeff[2][1],
+               matrix->coeff[2][2] - GIMP_TRANSFORM_NEAR_Z,
+               c_bezier, n_t_beziers,
+               start_in, end_in);
+
+  /* transform each of the resulting segments */
+  for (i = 0; i < *n_t_beziers; i++)
+    {
+      t_beziers[i] = g_queue_new ();
+
+      transform_bezier_coords (matrix, c_bezier[i], t_beziers[i], 3);
+    }
+}
diff --git a/app/core/gimp-transform-utils.h b/app/core/gimp-transform-utils.h
new file mode 100644
index 0000000..c2c1252
--- /dev/null
+++ b/app/core/gimp-transform-utils.h
@@ -0,0 +1,125 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-2001 Spencer Kimball, Peter Mattis, and others
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_TRANSFORM_UTILS_H__
+#define __GIMP_TRANSFORM_UTILS_H__
+
+
+#define GIMP_TRANSFORM_NEAR_Z 0.02
+
+
+void       gimp_transform_get_rotate_center    (gint                 x,
+                                                gint                 y,
+                                                gint                 width,
+                                                gint                 height,
+                                                gboolean             auto_center,
+                                                gdouble             *center_x,
+                                                gdouble             *center_y);
+void       gimp_transform_get_flip_axis        (gint                 x,
+                                                gint                 y,
+                                                gint                 width,
+                                                gint                 height,
+                                                GimpOrientationType  flip_type,
+                                                gboolean             auto_center,
+                                                gdouble             *axis);
+
+void       gimp_transform_matrix_flip          (GimpMatrix3         *matrix,
+                                                GimpOrientationType  flip_type,
+                                                gdouble              axis);
+void       gimp_transform_matrix_flip_free     (GimpMatrix3         *matrix,
+                                                gdouble              x1,
+                                                gdouble              y1,
+                                                gdouble              x2,
+                                                gdouble              y2);
+void       gimp_transform_matrix_rotate        (GimpMatrix3         *matrix,
+                                                GimpRotationType     rotate_type,
+                                                gdouble              center_x,
+                                                gdouble              center_y);
+void       gimp_transform_matrix_rotate_rect   (GimpMatrix3         *matrix,
+                                                gint                 x,
+                                                gint                 y,
+                                                gint                 width,
+                                                gint                 height,
+                                                gdouble              angle);
+void       gimp_transform_matrix_rotate_center (GimpMatrix3         *matrix,
+                                                gdouble              center_x,
+                                                gdouble              center_y,
+                                                gdouble              angle);
+void       gimp_transform_matrix_scale         (GimpMatrix3         *matrix,
+                                                gint                 x,
+                                                gint                 y,
+                                                gint                 width,
+                                                gint                 height,
+                                                gdouble              t_x,
+                                                gdouble              t_y,
+                                                gdouble              t_width,
+                                                gdouble              t_height);
+void       gimp_transform_matrix_shear         (GimpMatrix3         *matrix,
+                                                gint                 x,
+                                                gint                 y,
+                                                gint                 width,
+                                                gint                 height,
+                                                GimpOrientationType  orientation,
+                                                gdouble              amount);
+void       gimp_transform_matrix_perspective   (GimpMatrix3         *matrix,
+                                                gint                 x,
+                                                gint                 y,
+                                                gint                 width,
+                                                gint                 height,
+                                                gdouble              t_x1,
+                                                gdouble              t_y1,
+                                                gdouble              t_x2,
+                                                gdouble              t_y2,
+                                                gdouble              t_x3,
+                                                gdouble              t_y3,
+                                                gdouble              t_x4,
+                                                gdouble              t_y4);
+gboolean   gimp_transform_matrix_generic       (GimpMatrix3         *matrix,
+                                                const GimpVector2    input_points[4],
+                                                const GimpVector2    output_points[4]);
+
+gboolean   gimp_transform_polygon_is_convex    (gdouble              x1,
+                                                gdouble              y1,
+                                                gdouble              x2,
+                                                gdouble              y2,
+                                                gdouble              x3,
+                                                gdouble              y3,
+                                                gdouble              x4,
+                                                gdouble              y4);
+
+void       gimp_transform_polygon              (const GimpMatrix3   *matrix,
+                                                const GimpVector2   *vertices,
+                                                gint                 n_vertices,
+                                                gboolean             closed,
+                                                GimpVector2         *t_vertices,
+                                                gint                *n_t_vertices);
+void       gimp_transform_polygon_coords       (const GimpMatrix3   *matrix,
+                                                const GimpCoords    *vertices,
+                                                gint                 n_vertices,
+                                                gboolean             closed,
+                                                GimpCoords          *t_vertices,
+                                                gint                *n_t_vertices);
+
+void       gimp_transform_bezier_coords        (const GimpMatrix3   *matrix,
+                                                const GimpCoords     bezier[4],
+                                                GQueue              *t_beziers[2],
+                                                gint                *n_t_beziers,
+                                                gboolean            *start_in,
+                                                gboolean            *end_in);
+
+
+#endif  /*  __GIMP_TRANSFORM_UTILS_H__  */
diff --git a/app/core/gimp-units.c b/app/core/gimp-units.c
new file mode 100644
index 0000000..22caca1
--- /dev/null
+++ b/app/core/gimp-units.c
@@ -0,0 +1,488 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1999 Spencer Kimball and Peter Mattis
+ *
+ * gimpunit.c
+ * Copyright (C) 1999-2000 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/* This file contains functions to load & save the file containing the
+ * user-defined size units, when the application starts/finished.
+ */
+
+#include "config.h"
+
+#include <gio/gio.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpbase/gimpbase-private.h"
+#include "libgimpconfig/gimpconfig.h"
+
+#include "core-types.h"
+
+#include "gimp.h"
+#include "gimp-units.h"
+#include "gimpunit.h"
+
+#include "config/gimpconfig-file.h"
+
+#include "gimp-intl.h"
+
+
+/*
+ *  All deserialize functions return G_TOKEN_LEFT_PAREN on success,
+ *  or the GTokenType they would have expected but didn't get.
+ */
+
+static GTokenType gimp_unitrc_unit_info_deserialize (GScanner *scanner,
+                                                     Gimp     *gimp);
+
+
+static Gimp *the_unit_gimp = NULL;
+
+
+static gint
+gimp_units_get_number_of_units (void)
+{
+  return _gimp_unit_get_number_of_units (the_unit_gimp);
+}
+
+static gint
+gimp_units_get_number_of_built_in_units (void)
+{
+  return GIMP_UNIT_END;
+}
+
+static GimpUnit
+gimp_units_unit_new (gchar   *identifier,
+                     gdouble  factor,
+                     gint     digits,
+                     gchar   *symbol,
+                     gchar   *abbreviation,
+                     gchar   *singular,
+                     gchar   *plural)
+{
+  return _gimp_unit_new (the_unit_gimp,
+                         identifier,
+                         factor,
+                         digits,
+                         symbol,
+                         abbreviation,
+                         singular,
+                         plural);
+}
+
+static gboolean
+gimp_units_unit_get_deletion_flag (GimpUnit unit)
+{
+  return _gimp_unit_get_deletion_flag (the_unit_gimp, unit);
+}
+
+static void
+gimp_units_unit_set_deletion_flag (GimpUnit unit,
+                                   gboolean deletion_flag)
+{
+  _gimp_unit_set_deletion_flag (the_unit_gimp, unit, deletion_flag);
+}
+
+static gdouble
+gimp_units_unit_get_factor (GimpUnit unit)
+{
+  return _gimp_unit_get_factor (the_unit_gimp, unit);
+}
+
+static gint
+gimp_units_unit_get_digits (GimpUnit unit)
+{
+  return _gimp_unit_get_digits (the_unit_gimp, unit);
+}
+
+static const gchar *
+gimp_units_unit_get_identifier (GimpUnit unit)
+{
+  return _gimp_unit_get_identifier (the_unit_gimp, unit);
+}
+
+static const gchar *
+gimp_units_unit_get_symbol (GimpUnit unit)
+{
+  return _gimp_unit_get_symbol (the_unit_gimp, unit);
+}
+
+static const gchar *
+gimp_units_unit_get_abbreviation (GimpUnit unit)
+{
+  return _gimp_unit_get_abbreviation (the_unit_gimp, unit);
+}
+
+static const gchar *
+gimp_units_unit_get_singular (GimpUnit unit)
+{
+  return _gimp_unit_get_singular (the_unit_gimp, unit);
+}
+
+static const gchar *
+gimp_units_unit_get_plural (GimpUnit unit)
+{
+  return _gimp_unit_get_plural (the_unit_gimp, unit);
+}
+
+void
+gimp_units_init (Gimp *gimp)
+{
+  GimpUnitVtable vtable;
+
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+  g_return_if_fail (the_unit_gimp == NULL);
+
+  the_unit_gimp = gimp;
+
+  vtable.unit_get_number_of_units          = gimp_units_get_number_of_units;
+  vtable.unit_get_number_of_built_in_units = gimp_units_get_number_of_built_in_units;
+  vtable.unit_new               = gimp_units_unit_new;
+  vtable.unit_get_deletion_flag = gimp_units_unit_get_deletion_flag;
+  vtable.unit_set_deletion_flag = gimp_units_unit_set_deletion_flag;
+  vtable.unit_get_factor        = gimp_units_unit_get_factor;
+  vtable.unit_get_digits        = gimp_units_unit_get_digits;
+  vtable.unit_get_identifier    = gimp_units_unit_get_identifier;
+  vtable.unit_get_symbol        = gimp_units_unit_get_symbol;
+  vtable.unit_get_abbreviation  = gimp_units_unit_get_abbreviation;
+  vtable.unit_get_singular      = gimp_units_unit_get_singular;
+  vtable.unit_get_plural        = gimp_units_unit_get_plural;
+
+  gimp_base_init (&vtable);
+
+  gimp->user_units   = NULL;
+  gimp->n_user_units = 0;
+}
+
+void
+gimp_units_exit (Gimp *gimp)
+{
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+
+  gimp_user_units_free (gimp);
+}
+
+
+/*  unitrc functions  **********/
+
+enum
+{
+  UNIT_INFO = 1,
+  UNIT_FACTOR,
+  UNIT_DIGITS,
+  UNIT_SYMBOL,
+  UNIT_ABBREV,
+  UNIT_SINGULAR,
+  UNIT_PLURAL
+};
+
+void
+gimp_unitrc_load (Gimp *gimp)
+{
+  GFile      *file;
+  GScanner   *scanner;
+  GTokenType  token;
+  GError     *error = NULL;
+
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+
+  file = gimp_directory_file ("unitrc", NULL);
+
+  if (gimp->be_verbose)
+    g_print ("Parsing '%s'\n", gimp_file_get_utf8_name (file));
+
+  scanner = gimp_scanner_new_gfile (file, &error);
+
+  if (! scanner && error->code == GIMP_CONFIG_ERROR_OPEN_ENOENT)
+    {
+      g_clear_error (&error);
+      g_object_unref (file);
+
+      file = gimp_sysconf_directory_file ("unitrc", NULL);
+
+      scanner = gimp_scanner_new_gfile (file, NULL);
+    }
+
+  if (! scanner)
+    {
+      g_clear_error (&error);
+      g_object_unref (file);
+      return;
+    }
+
+  g_scanner_scope_add_symbol (scanner, 0,
+                              "unit-info", GINT_TO_POINTER (UNIT_INFO));
+  g_scanner_scope_add_symbol (scanner, UNIT_INFO,
+                              "factor", GINT_TO_POINTER (UNIT_FACTOR));
+  g_scanner_scope_add_symbol (scanner, UNIT_INFO,
+                              "digits", GINT_TO_POINTER (UNIT_DIGITS));
+  g_scanner_scope_add_symbol (scanner, UNIT_INFO,
+                              "symbol", GINT_TO_POINTER (UNIT_SYMBOL));
+  g_scanner_scope_add_symbol (scanner, UNIT_INFO,
+                              "abbreviation", GINT_TO_POINTER (UNIT_ABBREV));
+  g_scanner_scope_add_symbol (scanner, UNIT_INFO,
+                              "singular", GINT_TO_POINTER (UNIT_SINGULAR));
+  g_scanner_scope_add_symbol (scanner, UNIT_INFO,
+                              "plural", GINT_TO_POINTER (UNIT_PLURAL));
+
+  token = G_TOKEN_LEFT_PAREN;
+
+  while (g_scanner_peek_next_token (scanner) == token)
+    {
+      token = g_scanner_get_next_token (scanner);
+
+      switch (token)
+        {
+        case G_TOKEN_LEFT_PAREN:
+          token = G_TOKEN_SYMBOL;
+          break;
+
+        case G_TOKEN_SYMBOL:
+          if (scanner->value.v_symbol == GINT_TO_POINTER (UNIT_INFO))
+            {
+              g_scanner_set_scope (scanner, UNIT_INFO);
+              token = gimp_unitrc_unit_info_deserialize (scanner, gimp);
+
+              if (token == G_TOKEN_RIGHT_PAREN)
+                g_scanner_set_scope (scanner, 0);
+            }
+          break;
+
+        case G_TOKEN_RIGHT_PAREN:
+          token = G_TOKEN_LEFT_PAREN;
+          break;
+
+        default: /* do nothing */
+          break;
+        }
+    }
+
+  if (token != G_TOKEN_LEFT_PAREN)
+    {
+      g_scanner_get_next_token (scanner);
+      g_scanner_unexp_token (scanner, token, NULL, NULL, NULL,
+                             _("fatal parse error"), TRUE);
+
+      gimp_message_literal (gimp, NULL, GIMP_MESSAGE_ERROR, error->message);
+      g_clear_error (&error);
+
+      gimp_config_file_backup_on_error (file, "unitrc", NULL);
+    }
+
+  gimp_scanner_destroy (scanner);
+  g_object_unref (file);
+}
+
+void
+gimp_unitrc_save (Gimp *gimp)
+{
+  GimpConfigWriter *writer;
+  GFile            *file;
+  gint              i;
+  GError           *error = NULL;
+
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+
+  file = gimp_directory_file ("unitrc", NULL);
+
+  if (gimp->be_verbose)
+    g_print ("Writing '%s'\n", gimp_file_get_utf8_name (file));
+
+  writer =
+    gimp_config_writer_new_gfile (file,
+                                  TRUE,
+                                  "GIMP units\n\n"
+                                  "This file contains the user unit database. "
+                                  "You can edit this list with the unit "
+                                  "editor. You are not supposed to edit it "
+                                  "manually, but of course you can do.\n"
+                                  "This file will be entirely rewritten each "
+                                  "time you exit.",
+                                  NULL);
+
+  g_object_unref (file);
+
+  if (!writer)
+    return;
+
+  /*  save user defined units  */
+  for (i = _gimp_unit_get_number_of_built_in_units (gimp);
+       i < _gimp_unit_get_number_of_units (gimp);
+       i++)
+    {
+      if (_gimp_unit_get_deletion_flag (gimp, i) == FALSE)
+        {
+          gchar buf[G_ASCII_DTOSTR_BUF_SIZE];
+
+          gimp_config_writer_open (writer, "unit-info");
+          gimp_config_writer_string (writer,
+                                     _gimp_unit_get_identifier (gimp, i));
+
+          gimp_config_writer_open (writer, "factor");
+          gimp_config_writer_print (writer,
+                                    g_ascii_dtostr (buf, sizeof (buf),
+                                                    _gimp_unit_get_factor (gimp, i)),
+                                    -1);
+          gimp_config_writer_close (writer);
+
+          gimp_config_writer_open (writer, "digits");
+          gimp_config_writer_printf (writer,
+                                     "%d", _gimp_unit_get_digits (gimp, i));
+          gimp_config_writer_close (writer);
+
+          gimp_config_writer_open (writer, "symbol");
+          gimp_config_writer_string (writer,
+                                     _gimp_unit_get_symbol (gimp, i));
+          gimp_config_writer_close (writer);
+
+          gimp_config_writer_open (writer, "abbreviation");
+          gimp_config_writer_string (writer,
+                                     _gimp_unit_get_abbreviation (gimp, i));
+          gimp_config_writer_close (writer);
+
+          gimp_config_writer_open (writer, "singular");
+          gimp_config_writer_string (writer,
+                                     _gimp_unit_get_singular (gimp, i));
+          gimp_config_writer_close (writer);
+
+          gimp_config_writer_open (writer, "plural");
+          gimp_config_writer_string (writer,
+                                     _gimp_unit_get_plural (gimp, i));
+          gimp_config_writer_close (writer);
+
+          gimp_config_writer_close (writer);
+        }
+    }
+
+  if (! gimp_config_writer_finish (writer, "end of units", &error))
+    {
+      gimp_message_literal (gimp, NULL, GIMP_MESSAGE_ERROR, error->message);
+      g_clear_error (&error);
+    }
+}
+
+
+/*  private functions  */
+
+static GTokenType
+gimp_unitrc_unit_info_deserialize (GScanner *scanner,
+                                   Gimp     *gimp)
+{
+  gchar      *identifier   = NULL;
+  gdouble     factor       = 1.0;
+  gint        digits       = 2.0;
+  gchar      *symbol       = NULL;
+  gchar      *abbreviation = NULL;
+  gchar      *singular     = NULL;
+  gchar      *plural       = NULL;
+  GTokenType  token;
+
+  if (! gimp_scanner_parse_string (scanner, &identifier))
+    return G_TOKEN_STRING;
+
+  token = G_TOKEN_LEFT_PAREN;
+
+  while (g_scanner_peek_next_token (scanner) == token)
+    {
+      token = g_scanner_get_next_token (scanner);
+
+      switch (token)
+        {
+        case G_TOKEN_LEFT_PAREN:
+          token = G_TOKEN_SYMBOL;
+          break;
+
+        case G_TOKEN_SYMBOL:
+          switch (GPOINTER_TO_INT (scanner->value.v_symbol))
+            {
+            case UNIT_FACTOR:
+              token = G_TOKEN_FLOAT;
+              if (! gimp_scanner_parse_float (scanner, &factor))
+                goto cleanup;
+              break;
+
+            case UNIT_DIGITS:
+              token = G_TOKEN_INT;
+              if (! gimp_scanner_parse_int (scanner, &digits))
+                goto cleanup;
+              break;
+
+            case UNIT_SYMBOL:
+              token = G_TOKEN_STRING;
+              if (! gimp_scanner_parse_string (scanner, &symbol))
+                goto cleanup;
+              break;
+
+            case UNIT_ABBREV:
+              token = G_TOKEN_STRING;
+              if (! gimp_scanner_parse_string (scanner, &abbreviation))
+                goto cleanup;
+              break;
+
+            case UNIT_SINGULAR:
+              token = G_TOKEN_STRING;
+              if (! gimp_scanner_parse_string (scanner, &singular))
+                goto cleanup;
+              break;
+
+            case UNIT_PLURAL:
+              token = G_TOKEN_STRING;
+              if (! gimp_scanner_parse_string (scanner, &plural))
+                goto cleanup;
+             break;
+
+            default:
+              break;
+            }
+          token = G_TOKEN_RIGHT_PAREN;
+          break;
+
+        case G_TOKEN_RIGHT_PAREN:
+          token = G_TOKEN_LEFT_PAREN;
+          break;
+
+        default:
+          break;
+        }
+    }
+
+  if (token == G_TOKEN_LEFT_PAREN)
+    {
+      token = G_TOKEN_RIGHT_PAREN;
+
+      if (g_scanner_peek_next_token (scanner) == token)
+        {
+          GimpUnit unit = _gimp_unit_new (gimp,
+                                          identifier, factor, digits,
+                                          symbol, abbreviation,
+                                          singular, plural);
+
+          /*  make the unit definition persistent  */
+          _gimp_unit_set_deletion_flag (gimp, unit, FALSE);
+        }
+    }
+
+ cleanup:
+
+  g_free (identifier);
+  g_free (symbol);
+  g_free (abbreviation);
+  g_free (singular);
+  g_free (plural);
+
+  return token;
+}
diff --git a/app/core/gimp-units.h b/app/core/gimp-units.h
new file mode 100644
index 0000000..64f819a
--- /dev/null
+++ b/app/core/gimp-units.h
@@ -0,0 +1,29 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_UNITS_H__
+#define __GIMP_UNITS_H__
+
+
+void   gimp_units_init  (Gimp *gimp);
+void   gimp_units_exit  (Gimp *gimp);
+
+void   gimp_unitrc_load (Gimp *gimp);
+void   gimp_unitrc_save (Gimp *gimp);
+
+
+#endif  /*  __GIMP_UNITS_H__  */
diff --git a/app/core/gimp-user-install.c b/app/core/gimp-user-install.c
new file mode 100644
index 0000000..2b1c910
--- /dev/null
+++ b/app/core/gimp-user-install.c
@@ -0,0 +1,977 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimp-user-install.c
+ * Copyright (C) 2000-2008 Michael Natterer and Sven Neumann
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/* This file contains functions to help migrate the settings from a
+ * previous GIMP version to be used with the current (newer) version.
+ */
+
+#include "config.h"
+
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <sys/types.h>
+
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+
+#ifdef PLATFORM_OSX
+#include <AppKit/AppKit.h>
+#endif
+
+#include <gio/gio.h>
+#include <glib/gstdio.h>
+
+#ifdef G_OS_WIN32
+#include <libgimpbase/gimpwin32-io.h>
+#endif
+
+#include "libgimpbase/gimpbase.h"
+
+#include "core-types.h"
+
+#include "config/gimpconfig-file.h"
+#include "config/gimprc.h"
+
+#include "gimp-templates.h"
+#include "gimp-tags.h"
+#include "gimp-user-install.h"
+
+#include "gimp-intl.h"
+
+
+struct _GimpUserInstall
+{
+  GObject                 *gimp;
+
+  gboolean                verbose;
+
+  gchar                  *old_dir;
+  gint                    old_major;
+  gint                    old_minor;
+
+  const gchar            *migrate;
+
+  GimpUserInstallLogFunc  log;
+  gpointer                log_data;
+};
+
+typedef enum
+{
+  USER_INSTALL_MKDIR, /* Create the directory        */
+  USER_INSTALL_COPY   /* Copy from sysconf directory */
+} GimpUserInstallAction;
+
+static const struct
+{
+  const gchar           *name;
+  GimpUserInstallAction  action;
+}
+gimp_user_install_items[] =
+{
+  { "menurc",          USER_INSTALL_COPY  },
+  { "brushes",         USER_INSTALL_MKDIR },
+  { "dynamics",        USER_INSTALL_MKDIR },
+  { "fonts",           USER_INSTALL_MKDIR },
+  { "gradients",       USER_INSTALL_MKDIR },
+  { "palettes",        USER_INSTALL_MKDIR },
+  { "patterns",        USER_INSTALL_MKDIR },
+  { "tool-presets",    USER_INSTALL_MKDIR },
+  { "plug-ins",        USER_INSTALL_MKDIR },
+  { "modules",         USER_INSTALL_MKDIR },
+  { "interpreters",    USER_INSTALL_MKDIR },
+  { "environ",         USER_INSTALL_MKDIR },
+  { "scripts",         USER_INSTALL_MKDIR },
+  { "templates",       USER_INSTALL_MKDIR },
+  { "themes",          USER_INSTALL_MKDIR },
+  { "icons",           USER_INSTALL_MKDIR },
+  { "tmp",             USER_INSTALL_MKDIR },
+  { "curves",          USER_INSTALL_MKDIR },
+  { "levels",          USER_INSTALL_MKDIR },
+  { "filters",         USER_INSTALL_MKDIR },
+  { "fractalexplorer", USER_INSTALL_MKDIR },
+  { "gfig",            USER_INSTALL_MKDIR },
+  { "gflare",          USER_INSTALL_MKDIR },
+  { "gimpressionist",  USER_INSTALL_MKDIR }
+};
+
+
+static gboolean  user_install_detect_old         (GimpUserInstall    *install,
+                                                  const gchar        *gimp_dir);
+static gchar *   user_install_old_style_gimpdir  (void);
+
+static void      user_install_log                (GimpUserInstall    *install,
+                                                  const gchar        *format,
+                                                  ...) G_GNUC_PRINTF (2, 3);
+static void      user_install_log_newline        (GimpUserInstall    *install);
+static void      user_install_log_error          (GimpUserInstall    *install,
+                                                  GError            **error);
+
+static gboolean  user_install_mkdir              (GimpUserInstall    *install,
+                                                  const gchar        *dirname);
+static gboolean  user_install_mkdir_with_parents (GimpUserInstall    *install,
+                                                  const gchar        *dirname);
+static gboolean  user_install_file_copy          (GimpUserInstall    *install,
+                                                  const gchar        *source,
+                                                  const gchar        *dest,
+                                                  const gchar        *old_options_regexp,
+                                                  GRegexEvalCallback  update_callback);
+static gboolean  user_install_dir_copy           (GimpUserInstall    *install,
+                                                  gint                level,
+                                                  const gchar        *source,
+                                                  const gchar        *base,
+                                                  const gchar        *update_pattern,
+                                                  GRegexEvalCallback  update_callback);
+
+static gboolean  user_install_create_files       (GimpUserInstall    *install);
+static gboolean  user_install_migrate_files      (GimpUserInstall    *install);
+
+
+/*  public functions  */
+
+GimpUserInstall *
+gimp_user_install_new (GObject  *gimp,
+                       gboolean  verbose)
+{
+  GimpUserInstall *install = g_slice_new0 (GimpUserInstall);
+
+  install->gimp    = gimp;
+  install->verbose = verbose;
+
+  user_install_detect_old (install, gimp_directory ());
+
+#ifdef PLATFORM_OSX
+  /* The config path on OSX has for a very short time frame (2.8.2 only)
+     been "~/Library/GIMP". It changed to "~/Library/Application Support"
+     in 2.8.4 and was in the home folder (as was other UNIX) before. */
+
+  if (! install->old_dir)
+    {
+      gchar             *dir;
+      NSAutoreleasePool *pool;
+      NSArray           *path;
+      NSString          *library_dir;
+
+      pool = [[NSAutoreleasePool alloc] init];
+
+      path = NSSearchPathForDirectoriesInDomains (NSLibraryDirectory,
+                                                  NSUserDomainMask, YES);
+      library_dir = [path objectAtIndex:0];
+
+      dir = g_build_filename ([library_dir UTF8String],
+                              GIMPDIR, GIMP_USER_VERSION, NULL);
+
+      [pool drain];
+
+      user_install_detect_old (install, dir);
+      g_free (dir);
+    }
+
+#endif
+
+  if (! install->old_dir)
+    {
+      /* if the default XDG-style config directory was not found, try
+       * the "old-style" path in the home folder.
+       */
+      gchar *dir = user_install_old_style_gimpdir ();
+      user_install_detect_old (install, dir);
+      g_free (dir);
+    }
+
+  return install;
+}
+
+gboolean
+gimp_user_install_run (GimpUserInstall *install)
+{
+  gchar *dirname;
+
+  g_return_val_if_fail (install != NULL, FALSE);
+
+  dirname = g_filename_display_name (gimp_directory ());
+
+  if (install->migrate)
+    user_install_log (install,
+                      _("It seems you have used GIMP %s before.  "
+                        "GIMP will now migrate your user settings to '%s'."),
+                      install->migrate, dirname);
+  else
+    user_install_log (install,
+                      _("It appears that you are using GIMP for the "
+                        "first time.  GIMP will now create a folder "
+                        "named '%s' and copy some files to it."),
+                      dirname);
+
+  g_free (dirname);
+
+  user_install_log_newline (install);
+
+  if (! user_install_mkdir_with_parents (install, gimp_directory ()))
+    return FALSE;
+
+  if (install->migrate)
+    if (! user_install_migrate_files (install))
+      return FALSE;
+
+  return user_install_create_files (install);
+}
+
+void
+gimp_user_install_free (GimpUserInstall *install)
+{
+  g_return_if_fail (install != NULL);
+
+  g_free (install->old_dir);
+
+  g_slice_free (GimpUserInstall, install);
+}
+
+void
+gimp_user_install_set_log_handler (GimpUserInstall        *install,
+                                   GimpUserInstallLogFunc  log,
+                                   gpointer                user_data)
+{
+  g_return_if_fail (install != NULL);
+
+  install->log      = log;
+  install->log_data = user_data;
+}
+
+
+/*  Local functions  */
+
+static gboolean
+user_install_detect_old (GimpUserInstall *install,
+                         const gchar     *gimp_dir)
+{
+  gchar    *dir     = g_strdup (gimp_dir);
+  gchar    *version;
+  gboolean  migrate = FALSE;
+
+  version = strstr (dir, GIMP_APP_VERSION);
+
+  if (version)
+    {
+      gint i;
+
+      for (i = (GIMP_MINOR_VERSION & ~1); i >= 0; i -= 2)
+        {
+          /*  we assume that GIMP_APP_VERSION is in the form '2.x'  */
+          g_snprintf (version + 2, 2, "%d", i);
+
+          migrate = g_file_test (dir, G_FILE_TEST_IS_DIR);
+
+          if (migrate)
+            {
+#ifdef GIMP_UNSTABLE
+              g_printerr ("gimp-user-install: migrating from %s\n", dir);
+#endif
+              install->old_major = 2;
+              install->old_minor = i;
+
+              break;
+            }
+        }
+    }
+
+  if (migrate)
+    {
+      install->old_dir = dir;
+      install->migrate = (const gchar *) version;
+    }
+  else
+    {
+      g_free (dir);
+    }
+
+  return migrate;
+}
+
+static gchar *
+user_install_old_style_gimpdir (void)
+{
+  const gchar *home_dir = g_get_home_dir ();
+  gchar       *gimp_dir = NULL;
+
+  if (home_dir)
+    {
+      gimp_dir = g_build_filename (home_dir, ".gimp-" GIMP_APP_VERSION, NULL);
+    }
+  else
+    {
+      gchar *user_name = g_strdup (g_get_user_name ());
+      gchar *subdir_name;
+
+#ifdef G_OS_WIN32
+      gchar *p = user_name;
+
+      while (*p)
+        {
+          /* Replace funny characters in the user name with an
+           * underscore. The code below also replaces some
+           * characters that in fact are legal in file names, but
+           * who cares, as long as the definitely illegal ones are
+           * caught.
+           */
+          if (!g_ascii_isalnum (*p) && !strchr ("-.,@=", *p))
+            *p = '_';
+          p++;
+        }
+#endif
+
+#ifndef G_OS_WIN32
+      g_message ("warning: no home directory.");
+#endif
+      subdir_name = g_strconcat (".gimp-" GIMP_APP_VERSION ".", user_name, NULL);
+      gimp_dir = g_build_filename (gimp_data_directory (),
+                                   subdir_name,
+                                   NULL);
+      g_free (user_name);
+      g_free (subdir_name);
+    }
+
+  return gimp_dir;
+}
+
+static void
+user_install_log (GimpUserInstall *install,
+                  const gchar     *format,
+                  ...)
+{
+  va_list args;
+
+  va_start (args, format);
+
+  if (format)
+    {
+      gchar *message = g_strdup_vprintf (format, args);
+
+      if (install->verbose)
+        g_print ("%s\n", message);
+
+      if (install->log)
+        install->log (message, FALSE, install->log_data);
+
+      g_free (message);
+    }
+
+  va_end (args);
+}
+
+static void
+user_install_log_newline (GimpUserInstall *install)
+{
+  if (install->verbose)
+    g_print ("\n");
+
+  if (install->log)
+    install->log (NULL, FALSE, install->log_data);
+}
+
+static void
+user_install_log_error (GimpUserInstall  *install,
+                        GError          **error)
+{
+  if (error && *error)
+    {
+      const gchar *message = ((*error)->message ?
+                              (*error)->message : "(unknown error)");
+
+      if (install->log)
+        install->log (message, TRUE, install->log_data);
+      else
+        g_print ("error: %s\n", message);
+
+      g_clear_error (error);
+    }
+}
+
+static gboolean
+user_install_file_copy (GimpUserInstall    *install,
+                        const gchar        *source,
+                        const gchar        *dest,
+                        const gchar        *old_options_regexp,
+                        GRegexEvalCallback  update_callback)
+{
+  GError   *error = NULL;
+  gboolean  success;
+
+  user_install_log (install, _("Copying file '%s' from '%s'..."),
+                    gimp_filename_to_utf8 (dest),
+                    gimp_filename_to_utf8 (source));
+
+  success = gimp_config_file_copy (source, dest, old_options_regexp, update_callback, &error);
+
+  user_install_log_error (install, &error);
+
+  return success;
+}
+
+static gboolean
+user_install_mkdir (GimpUserInstall *install,
+                    const gchar     *dirname)
+{
+  user_install_log (install, _("Creating folder '%s'..."),
+                    gimp_filename_to_utf8 (dirname));
+
+  if (g_mkdir (dirname,
+               S_IRUSR | S_IWUSR | S_IXUSR |
+               S_IRGRP | S_IXGRP |
+               S_IROTH | S_IXOTH) == -1)
+    {
+      GError *error = NULL;
+
+      g_set_error (&error, G_FILE_ERROR, g_file_error_from_errno (errno),
+                   _("Cannot create folder '%s': %s"),
+                   gimp_filename_to_utf8 (dirname), g_strerror (errno));
+
+      user_install_log_error (install, &error);
+
+      return FALSE;
+    }
+
+  return TRUE;
+}
+
+static gboolean
+user_install_mkdir_with_parents (GimpUserInstall *install,
+                                 const gchar     *dirname)
+{
+  user_install_log (install, _("Creating folder '%s'..."),
+                    gimp_filename_to_utf8 (dirname));
+
+  if (g_mkdir_with_parents (dirname,
+                            S_IRUSR | S_IWUSR | S_IXUSR |
+                            S_IRGRP | S_IXGRP |
+                            S_IROTH | S_IXOTH) == -1)
+    {
+      GError *error = NULL;
+
+      g_set_error (&error, G_FILE_ERROR, g_file_error_from_errno (errno),
+                   _("Cannot create folder '%s': %s"),
+                   gimp_filename_to_utf8 (dirname), g_strerror (errno));
+
+      user_install_log_error (install, &error);
+
+      return FALSE;
+    }
+
+  return TRUE;
+}
+
+/* The regexp pattern of all options changed from menurc of GIMP 2.8.
+ * Add any pattern that we want to recognize for replacement in the menurc of
+ * the next release
+ */
+#define MENURC_OVER20_UPDATE_PATTERN \
+  "\"<Actions>/buffers/buffers-paste-as-new\""  "|" \
+  "\"<Actions>/edit/edit-paste-as-new\""        "|" \
+  "\"<Actions>/file/file-export\""              "|" \
+  "\"<Actions>/file/file-export-to\""           "|" \
+  "\"<Actions>/layers/layers-text-tool\""       "|" \
+  "\"<Actions>/plug-in/plug-in-gauss\""         "|" \
+  "\"<Actions>/tools/tools-value-[1-4]-.*\""    "|" \
+  "\"<Actions>/vectors/vectors-path-tool\""     "|" \
+  "\"<Actions>/tools/tools-blend\""
+
+/**
+ * callback to use for updating a menurc from GIMP over 2.0.
+ * data is unused (always NULL).
+ * The updated value will be matched line by line.
+ */
+static gboolean
+user_update_menurc_over20 (const GMatchInfo *matched_value,
+                           GString          *new_value,
+                           gpointer          data)
+{
+  gchar *match = g_match_info_fetch (matched_value, 0);
+
+  /* "*-paste-as-new" renamed to "*-paste-as-new-image"
+   */
+  if (g_strcmp0 (match, "\"<Actions>/buffers/buffers-paste-as-new\"") == 0)
+    {
+      g_string_append (new_value, "\"<Actions>/buffers/buffers-paste-as-new-image\"");
+    }
+  else if (g_strcmp0 (match, "\"<Actions>/edit/edit-paste-as-new\"") == 0)
+    {
+      g_string_append (new_value, "\"<Actions>/edit/edit-paste-as-new-image\"");
+    }
+  /* file-export-* changes to follow file-save-* patterns.  Actions
+   * available since GIMP 2.8, changed for 2.10 in commit 4b14ed2.
+   */
+  else if (g_strcmp0 (match, "\"<Actions>/file/file-export\"") == 0)
+    {
+      g_string_append (new_value, "\"<Actions>/file/file-export-as\"");
+    }
+  else if (g_strcmp0 (match, "\"<Actions>/file/file-export-to\"") == 0)
+    {
+      g_string_append (new_value, "\"<Actions>/file/file-export\"");
+    }
+  else if (g_strcmp0 (match, "\"<Actions>/layers/layers-text-tool\"") == 0)
+    {
+      g_string_append (new_value, "\"<Actions>/layers/layers-edit\"");
+    }
+  /* plug-in-gauss doesn't exist anymore since commit ff59aebbe88.
+   * The expected replacement would be filters-gaussian-blur which is
+   * gegl:gaussian-blur operation. See also bug 775931.
+   */
+  else if (g_strcmp0 (match, "\"<Actions>/plug-in/plug-in-gauss\"") == 0)
+    {
+      g_string_append (new_value, "\"<Actions>/filters/filters-gaussian-blur\"");
+    }
+  /* Tools settings renamed more user-friendly.  Actions available
+   * since GIMP 2.4, changed for 2.10 in commit 0bdb747.
+   */
+  else if (g_str_has_prefix (match, "\"<Actions>/tools/tools-value-1-"))
+    {
+      g_string_append (new_value, "\"<Actions>/tools/tools-opacity-");
+      g_string_append (new_value, match + 31);
+    }
+  else if (g_str_has_prefix (match, "\"<Actions>/tools/tools-value-2-"))
+    {
+      g_string_append (new_value, "\"<Actions>/tools/tools-size-");
+      g_string_append (new_value, match + 31);
+    }
+  else if (g_str_has_prefix (match, "\"<Actions>/tools/tools-value-3-"))
+    {
+      g_string_append (new_value, "\"<Actions>/tools/tools-aspect-");
+      g_string_append (new_value, match + 31);
+    }
+  else if (g_str_has_prefix (match, "\"<Actions>/tools/tools-value-4-"))
+    {
+      g_string_append (new_value, "\"<Actions>/tools/tools-angle-");
+      g_string_append (new_value, match + 31);
+    }
+  else if (g_strcmp0 (match, "\"<Actions>/vectors/vectors-path-tool\"") == 0)
+    {
+      g_string_append (new_value, "\"<Actions>/vectors/vectors-edit\"");
+    }
+  else if (g_strcmp0 (match, "\"<Actions>/tools/tools-blend\"") == 0)
+    {
+      g_string_append (new_value, "\"<Actions>/tools/tools-gradient\"");
+    }
+  /* Should not happen. Just in case we match something unexpected by
+   * mistake.
+   */
+  else
+    {
+      g_message ("(WARNING) %s: invalid match \"%s\"", G_STRFUNC, match);
+      g_string_append (new_value, match);
+    }
+
+  g_free (match);
+  return FALSE;
+}
+
+#define CONTROLLERRC_UPDATE_PATTERN \
+  "\\(map \"(scroll|cursor)-[^\"]*\\bcontrol\\b[^\"]*\""
+
+static gboolean
+user_update_controllerrc (const GMatchInfo *matched_value,
+                          GString          *new_value,
+                          gpointer          data)
+{
+  gchar  *original;
+  gchar  *replacement;
+  GRegex *regexp = NULL;
+
+  /* No need of a complicated pattern here.
+   * CONTROLLERRC_UPDATE_PATTERN took care of it first.
+   */
+  regexp   = g_regex_new ("\\bcontrol\\b", 0, 0, NULL);
+  original = g_match_info_fetch (matched_value, 0);
+
+  replacement = g_regex_replace (regexp, original, -1, 0,
+                                 "primary", 0, NULL);
+  g_string_append (new_value, replacement);
+
+  g_free (original);
+  g_free (replacement);
+  g_regex_unref (regexp);
+
+  return FALSE;
+}
+
+#define GIMPRC_UPDATE_PATTERN \
+  "\\(theme [^)]*\\)"    "|" \
+  "\\(.*-path [^)]*\\)"
+
+static gboolean
+user_update_gimprc (const GMatchInfo *matched_value,
+                    GString          *new_value,
+                    gpointer          data)
+{
+  /* Do not migrate paths and themes from GIMP < 2.10. */
+  return FALSE;
+}
+
+#define GIMPRESSIONIST_UPDATE_PATTERN \
+  "selectedbrush=Brushes/paintbrush.pgm"
+
+static gboolean
+user_update_gimpressionist (const GMatchInfo *matched_value,
+                            GString          *new_value,
+                            gpointer          data)
+{
+  gchar *match = g_match_info_fetch (matched_value, 0);
+
+  /* See bug 791934: both brushes are identical. */
+  if (g_strcmp0 (match, "selectedbrush=Brushes/paintbrush.pgm") == 0)
+    {
+      g_string_append (new_value, "selectedbrush=Brushes/paintbrush01.pgm");
+    }
+  else
+    {
+      g_message ("(WARNING) %s: invalid match \"%s\"", G_STRFUNC, match);
+      g_string_append (new_value, match);
+    }
+
+  g_free (match);
+  return FALSE;
+}
+
+#define TOOL_PRESETS_UPDATE_PATTERN \
+  "GimpImageMapOptions"  "|" \
+  "GimpBlendOptions"     "|" \
+  "gimp-blend-tool"      "|" \
+  "gimp-tool-blend"
+
+static gboolean
+user_update_tool_presets (const GMatchInfo *matched_value,
+                          GString          *new_value,
+                          gpointer          data)
+{
+  gchar *match = g_match_info_fetch (matched_value, 0);
+
+  if (g_strcmp0 (match, "GimpImageMapOptions") == 0)
+    {
+      g_string_append (new_value, "GimpFilterOptions");
+    }
+  else if (g_strcmp0 (match, "GimpBlendOptions") == 0)
+    {
+      g_string_append (new_value, "GimpGradientOptions");
+    }
+  else if (g_strcmp0 (match, "gimp-blend-tool") == 0)
+    {
+      g_string_append (new_value, "gimp-gradient-tool");
+    }
+  else if (g_strcmp0 (match, "gimp-tool-blend") == 0)
+    {
+      g_string_append (new_value, "gimp-tool-gradient");
+    }
+  else
+    {
+      g_message ("(WARNING) %s: invalid match \"%s\"", G_STRFUNC, match);
+      g_string_append (new_value, match);
+    }
+
+  g_free (match);
+  return FALSE;
+}
+
+/* Actually not only for contextrc, but all other files where
+ * gimp-blend-tool may appear. Apparently that is also "devicerc", as
+ * well as "toolrc" (but this one is skipped anyway).
+ */
+#define CONTEXTRC_UPDATE_PATTERN "gimp-blend-tool"
+
+static gboolean
+user_update_contextrc_over20 (const GMatchInfo *matched_value,
+                              GString          *new_value,
+                              gpointer          data)
+{
+  gchar *match = g_match_info_fetch (matched_value, 0);
+
+  if (g_strcmp0 (match, "gimp-blend-tool") == 0)
+    {
+      g_string_append (new_value, "gimp-gradient-tool");
+    }
+  else
+    {
+      g_message ("(WARNING) %s: invalid match \"%s\"", G_STRFUNC, match);
+      g_string_append (new_value, match);
+    }
+
+  g_free (match);
+  return FALSE;
+}
+
+static gboolean
+user_install_dir_copy (GimpUserInstall    *install,
+                       gint                level,
+                       const gchar        *source,
+                       const gchar        *base,
+                       const gchar        *update_pattern,
+                       GRegexEvalCallback  update_callback)
+{
+  GDir        *source_dir = NULL;
+  GDir        *dest_dir   = NULL;
+  gchar        dest[1024];
+  const gchar *basename;
+  gchar       *dirname = NULL;
+  gchar       *name;
+  GError      *error   = NULL;
+  gboolean     success = FALSE;
+
+  if (level >= 5)
+    {
+      /* Config migration is recursive, but we can't go on forever,
+       * since we may fall into recursive symlinks in particular (which
+       * is a security risk to fill a disk, and would also block GIMP
+       * forever at migration stage).
+       * Let's just break the recursivity at 5 levels, which is just an
+       * arbitrary value (but I don't think there should be any data
+       * deeper than this).
+       */
+      goto error;
+    }
+
+  name = g_path_get_basename (source);
+  dirname = g_build_filename (base, name, NULL);
+  g_free (name);
+
+  success = user_install_mkdir (install, dirname);
+  if (! success)
+    goto error;
+
+  success = (dest_dir = g_dir_open (dirname, 0, &error)) != NULL;
+  if (! success)
+    goto error;
+
+  success = (source_dir = g_dir_open (source, 0, &error)) != NULL;
+  if (! success)
+    goto error;
+
+  while ((basename = g_dir_read_name (source_dir)) != NULL)
+    {
+      name = g_build_filename (source, basename, NULL);
+
+      if (g_file_test (name, G_FILE_TEST_IS_REGULAR))
+        {
+          g_snprintf (dest, sizeof (dest), "%s%c%s",
+                      dirname, G_DIR_SEPARATOR, basename);
+
+          success = user_install_file_copy (install, name, dest,
+                                            update_pattern,
+                                            update_callback);
+          if (! success)
+            {
+              g_free (name);
+              goto error;
+            }
+        }
+      else
+        {
+          user_install_dir_copy (install, level + 1, name, dirname,
+                                 update_pattern, update_callback);
+        }
+
+      g_free (name);
+    }
+
+ error:
+  user_install_log_error (install, &error);
+
+  if (source_dir)
+    g_dir_close (source_dir);
+
+  if (dest_dir)
+    g_dir_close (dest_dir);
+
+  if (dirname)
+    g_free (dirname);
+
+  return success;
+}
+
+static gboolean
+user_install_create_files (GimpUserInstall *install)
+{
+  gchar dest[1024];
+  gchar source[1024];
+  gint  i;
+
+  for (i = 0; i < G_N_ELEMENTS (gimp_user_install_items); i++)
+    {
+      g_snprintf (dest, sizeof (dest), "%s%c%s",
+                  gimp_directory (),
+                  G_DIR_SEPARATOR,
+                  gimp_user_install_items[i].name);
+
+      if (g_file_test (dest, G_FILE_TEST_EXISTS))
+        continue;
+
+      switch (gimp_user_install_items[i].action)
+        {
+        case USER_INSTALL_MKDIR:
+          if (! user_install_mkdir (install, dest))
+            return FALSE;
+          break;
+
+        case USER_INSTALL_COPY:
+          g_snprintf (source, sizeof (source), "%s%c%s",
+                      gimp_sysconf_directory (), G_DIR_SEPARATOR,
+                      gimp_user_install_items[i].name);
+
+          if (! user_install_file_copy (install, source, dest, NULL, NULL))
+            return FALSE;
+          break;
+        }
+    }
+
+  g_snprintf (dest, sizeof (dest), "%s%c%s",
+              gimp_directory (), G_DIR_SEPARATOR, "tags.xml");
+
+  if (! g_file_test (dest, G_FILE_TEST_IS_REGULAR))
+    {
+      /* if there was no tags.xml, install it with default tag set.
+       */
+      if (! gimp_tags_user_install ())
+        {
+          return FALSE;
+        }
+    }
+
+  return TRUE;
+}
+
+static gboolean
+user_install_migrate_files (GimpUserInstall *install)
+{
+  GDir        *dir;
+  const gchar *basename;
+  gchar        dest[1024];
+  GimpRc      *gimprc;
+  GError      *error = NULL;
+
+  dir = g_dir_open (install->old_dir, 0, &error);
+
+  if (! dir)
+    {
+      user_install_log_error (install, &error);
+      return FALSE;
+    }
+
+  while ((basename = g_dir_read_name (dir)) != NULL)
+    {
+      gchar *source = g_build_filename (install->old_dir, basename, NULL);
+
+      if (g_file_test (source, G_FILE_TEST_IS_REGULAR))
+        {
+          const gchar        *update_pattern = NULL;
+          GRegexEvalCallback  update_callback = NULL;
+
+          /*  skip these files for all old versions  */
+          if (strcmp (basename, "documents") == 0      ||
+              g_str_has_prefix (basename, "gimpswap.") ||
+              strcmp (basename, "pluginrc") == 0       ||
+              strcmp (basename, "themerc") == 0        ||
+              strcmp (basename, "toolrc") == 0)
+            {
+              goto next_file;
+            }
+          else if (strcmp (basename, "menurc") == 0)
+            {
+              switch (install->old_minor)
+                {
+                case 0:
+                  /*  skip menurc for gimp 2.0 as the format has changed  */
+                  goto next_file;
+                  break;
+                default:
+                  update_pattern  = MENURC_OVER20_UPDATE_PATTERN;
+                  update_callback = user_update_menurc_over20;
+                  break;
+                }
+            }
+          else if (strcmp (basename, "controllerrc") == 0)
+            {
+              update_pattern  = CONTROLLERRC_UPDATE_PATTERN;
+              update_callback = user_update_controllerrc;
+            }
+          else if (strcmp (basename, "gimprc") == 0)
+            {
+              update_pattern  = GIMPRC_UPDATE_PATTERN;
+              update_callback = user_update_gimprc;
+            }
+          else if (strcmp (basename, "contextrc") == 0      ||
+                   strcmp (basename, "devicerc") == 0)
+            {
+              update_pattern  = CONTEXTRC_UPDATE_PATTERN;
+              update_callback = user_update_contextrc_over20;
+            }
+
+          g_snprintf (dest, sizeof (dest), "%s%c%s",
+                      gimp_directory (), G_DIR_SEPARATOR, basename);
+
+          user_install_file_copy (install, source, dest,
+                                  update_pattern, update_callback);
+        }
+      else if (g_file_test (source, G_FILE_TEST_IS_DIR))
+        {
+          const gchar        *update_pattern = NULL;
+          GRegexEvalCallback  update_callback = NULL;
+
+          /*  skip these directories for all old versions  */
+          if (strcmp (basename, "tmp") == 0          ||
+              strcmp (basename, "tool-options") == 0 ||
+              strcmp (basename, "themes") == 0)
+            {
+              goto next_file;
+            }
+
+          if (strcmp (basename, "gimpressionist") == 0)
+            {
+              update_pattern  = GIMPRESSIONIST_UPDATE_PATTERN;
+              update_callback = user_update_gimpressionist;
+            }
+          else if (strcmp (basename, "tool-presets") == 0)
+            {
+              update_pattern  = TOOL_PRESETS_UPDATE_PATTERN;
+              update_callback = user_update_tool_presets;
+            }
+          user_install_dir_copy (install, 0, source, gimp_directory (),
+                                 update_pattern, update_callback);
+        }
+
+    next_file:
+      g_free (source);
+    }
+
+  /*  create the tmp directory that was explicitly not copied  */
+
+  g_snprintf (dest, sizeof (dest), "%s%c%s",
+              gimp_directory (), G_DIR_SEPARATOR, "tmp");
+
+  user_install_mkdir (install, dest);
+  g_dir_close (dir);
+
+  gimp_templates_migrate (install->old_dir);
+
+  gimprc = gimp_rc_new (install->gimp, NULL, NULL, FALSE);
+  gimp_rc_migrate (gimprc);
+  gimp_rc_save (gimprc);
+  g_object_unref (gimprc);
+
+  return TRUE;
+}
diff --git a/app/core/gimp-user-install.h b/app/core/gimp-user-install.h
new file mode 100644
index 0000000..1bac686
--- /dev/null
+++ b/app/core/gimp-user-install.h
@@ -0,0 +1,39 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_USER_INSTALL_H__
+#define __GIMP_USER_INSTALL_H__
+
+
+typedef struct _GimpUserInstall GimpUserInstall;
+
+typedef void  (* GimpUserInstallLogFunc) (const gchar *message,
+                                          gboolean     error,
+                                          gpointer     user_data);
+
+
+GimpUserInstall * gimp_user_install_new  (GObject          *gimp,
+                                          gboolean          verbose);
+gboolean          gimp_user_install_run  (GimpUserInstall  *install);
+void              gimp_user_install_free (GimpUserInstall  *install);
+
+void   gimp_user_install_set_log_handler (GimpUserInstall        *install,
+                                          GimpUserInstallLogFunc  log,
+                                          gpointer                user_data);
+
+
+#endif /* __USER_INSTALL_H__ */
diff --git a/app/core/gimp-utils.c b/app/core/gimp-utils.c
new file mode 100644
index 0000000..d3df098
--- /dev/null
+++ b/app/core/gimp-utils.c
@@ -0,0 +1,1098 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+#include <locale.h>
+
+#ifdef HAVE__NL_MEASUREMENT_MEASUREMENT
+#include <langinfo.h>
+#endif
+
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+
+#include <glib.h>
+
+#ifdef G_OS_WIN32
+#define _WIN32_WINNT 0x0500
+#include <windows.h>
+#include <process.h>
+#endif
+
+#if defined(G_OS_UNIX) && defined(HAVE_EXECINFO_H)
+/* For get_backtrace() */
+#include <stdlib.h>
+#include <string.h>
+#include <execinfo.h>
+#endif
+
+#include <cairo.h>
+#include <gegl.h>
+#include <gobject/gvaluecollector.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpmath/gimpmath.h"
+#include "libgimpcolor/gimpcolor.h"
+
+#include "core-types.h"
+
+#include "gimp.h"
+#include "gimp-utils.h"
+#include "gimpasync.h"
+#include "gimpcontext.h"
+#include "gimperror.h"
+
+#include "gimp-intl.h"
+
+
+#define MAX_FUNC 100
+
+
+gint
+gimp_get_pid (void)
+{
+  return (gint) getpid ();
+}
+
+guint64
+gimp_get_physical_memory_size (void)
+{
+#ifdef G_OS_UNIX
+#if defined(HAVE_UNISTD_H) && defined(_SC_PHYS_PAGES) && defined (_SC_PAGE_SIZE)
+  return (guint64) sysconf (_SC_PHYS_PAGES) * sysconf (_SC_PAGE_SIZE);
+#endif
+#endif
+
+#ifdef G_OS_WIN32
+# if defined(_MSC_VER) && (_MSC_VER <= 1200)
+  MEMORYSTATUS memory_status;
+  memory_status.dwLength = sizeof (memory_status);
+
+  GlobalMemoryStatus (&memory_status);
+  return memory_status.dwTotalPhys;
+# else
+  /* requires w2k and newer SDK than provided with msvc6 */
+  MEMORYSTATUSEX memory_status;
+
+  memory_status.dwLength = sizeof (memory_status);
+
+  if (GlobalMemoryStatusEx (&memory_status))
+    return memory_status.ullTotalPhys;
+# endif
+#endif
+
+  return 0;
+}
+
+/*
+ *  basically copied from gtk_get_default_language()
+ */
+gchar *
+gimp_get_default_language (const gchar *category)
+{
+  gchar *lang;
+  gchar *p;
+  gint   cat = LC_CTYPE;
+
+  if (! category)
+    category = "LC_CTYPE";
+
+#ifdef G_OS_WIN32
+
+  p = getenv ("LC_ALL");
+  if (p != NULL)
+    lang = g_strdup (p);
+  else
+    {
+      p = getenv ("LANG");
+      if (p != NULL)
+        lang = g_strdup (p);
+      else
+        {
+          p = getenv (category);
+          if (p != NULL)
+            lang = g_strdup (p);
+          else
+            lang = g_win32_getlocale ();
+        }
+    }
+
+#else
+
+  if (strcmp (category, "LC_CTYPE") == 0)
+    cat = LC_CTYPE;
+  else if (strcmp (category, "LC_MESSAGES") == 0)
+    cat = LC_MESSAGES;
+  else
+    g_warning ("unsupported category used with gimp_get_default_language()");
+
+  lang = g_strdup (setlocale (cat, NULL));
+
+#endif
+
+  p = strchr (lang, '.');
+  if (p)
+    *p = '\0';
+  p = strchr (lang, '@');
+  if (p)
+    *p = '\0';
+
+  return lang;
+}
+
+GimpUnit
+gimp_get_default_unit (void)
+{
+#if defined (HAVE__NL_MEASUREMENT_MEASUREMENT)
+  const gchar *measurement = nl_langinfo (_NL_MEASUREMENT_MEASUREMENT);
+
+  switch (*((guchar *) measurement))
+    {
+    case 1: /* metric   */
+      return GIMP_UNIT_MM;
+
+    case 2: /* imperial */
+      return GIMP_UNIT_INCH;
+    }
+
+#elif defined (G_OS_WIN32)
+  DWORD measurement;
+  int   ret;
+
+  ret = GetLocaleInfo(LOCALE_USER_DEFAULT,
+                      LOCALE_IMEASURE | LOCALE_RETURN_NUMBER,
+                      (LPTSTR)&measurement,
+                      sizeof(measurement) / sizeof(TCHAR) );
+
+  if (ret != 0) /* GetLocaleInfo succeeded */
+    {
+    switch ((guint) measurement)
+      {
+      case 0: /* metric */
+        return GIMP_UNIT_MM;
+
+      case 1: /* imperial */
+        return GIMP_UNIT_INCH;
+      }
+    }
+#endif
+
+  return GIMP_UNIT_MM;
+}
+
+gchar **
+gimp_properties_append (GType    object_type,
+                        gint    *n_properties,
+                        gchar  **names,
+                        GValue **values,
+                        ...)
+{
+  va_list args;
+
+  g_return_val_if_fail (g_type_is_a (object_type, G_TYPE_OBJECT), NULL);
+  g_return_val_if_fail (n_properties != NULL, NULL);
+  g_return_val_if_fail (names != NULL || *n_properties == 0, NULL);
+  g_return_val_if_fail (values != NULL || *n_properties == 0, NULL);
+
+  va_start (args, values);
+  names = gimp_properties_append_valist (object_type, n_properties,
+                                         names, values, args);
+  va_end (args);
+
+  return names;
+}
+
+gchar **
+gimp_properties_append_valist (GType     object_type,
+                               gint      *n_properties,
+                               gchar   **names,
+                               GValue  **values,
+                               va_list   args)
+{
+  GObjectClass *object_class;
+  gchar        *param_name;
+
+  g_return_val_if_fail (g_type_is_a (object_type, G_TYPE_OBJECT), NULL);
+  g_return_val_if_fail (n_properties != NULL, NULL);
+  g_return_val_if_fail (names != NULL || *n_properties == 0, NULL);
+  g_return_val_if_fail (values != NULL || *n_properties == 0, NULL);
+
+  object_class = g_type_class_ref (object_type);
+
+  param_name = va_arg (args, gchar *);
+
+  while (param_name)
+    {
+      GValue     *value;
+      gchar      *error = NULL;
+      GParamSpec *pspec = g_object_class_find_property (object_class,
+                                                        param_name);
+
+      if (! pspec)
+        {
+          g_warning ("%s: object class `%s' has no property named `%s'",
+                     G_STRFUNC, g_type_name (object_type), param_name);
+          break;
+        }
+
+      names   = g_renew (gchar *, names,   *n_properties + 1);
+      *values = g_renew (GValue,  *values, *n_properties + 1);
+
+      value = &((*values)[*n_properties]);
+
+      names[*n_properties] = g_strdup (param_name);
+      value->g_type = 0;
+
+      g_value_init (value, G_PARAM_SPEC_VALUE_TYPE (pspec));
+
+      G_VALUE_COLLECT (value, args, 0, &error);
+
+      if (error)
+        {
+          g_warning ("%s: %s", G_STRFUNC, error);
+          g_free (error);
+          g_free (names[*n_properties]);
+          g_value_unset (value);
+          break;
+        }
+
+      *n_properties = *n_properties + 1;
+
+      param_name = va_arg (args, gchar *);
+    }
+
+  g_type_class_unref (object_class);
+
+  return names;
+}
+
+void
+gimp_properties_free (gint     n_properties,
+                      gchar  **names,
+                      GValue  *values)
+{
+  g_return_if_fail (names  != NULL || n_properties == 0);
+  g_return_if_fail (values != NULL || n_properties == 0);
+
+  if (names && values)
+    {
+      gint i;
+
+      for (i = 0; i < n_properties; i++)
+        {
+          g_free (names[i]);
+          g_value_unset (&values[i]);
+        }
+
+      g_free (names);
+      g_free (values);
+    }
+}
+
+/*  markup unescape code stolen and adapted from gmarkup.c
+ */
+static gchar *
+char_str (gunichar c,
+          gchar   *buf)
+{
+  memset (buf, 0, 8);
+  g_unichar_to_utf8 (c, buf);
+  return buf;
+}
+
+static gboolean
+unescape_gstring (GString *string)
+{
+  const gchar *from;
+  gchar       *to;
+
+  /*
+   * Meeks' theorum: unescaping can only shrink text.
+   * for &lt; etc. this is obvious, for &#xffff; more
+   * thought is required, but this is patently so.
+   */
+  for (from = to = string->str; *from != '\0'; from++, to++)
+    {
+      *to = *from;
+
+      if (*to == '\r')
+        {
+          *to = '\n';
+          if (from[1] == '\n')
+            from++;
+        }
+      if (*from == '&')
+        {
+          from++;
+          if (*from == '#')
+            {
+              gboolean is_hex = FALSE;
+              gulong   l;
+              gchar   *end = NULL;
+
+              from++;
+
+              if (*from == 'x')
+                {
+                  is_hex = TRUE;
+                  from++;
+                }
+
+              /* digit is between start and p */
+              errno = 0;
+              if (is_hex)
+                l = strtoul (from, &end, 16);
+              else
+                l = strtoul (from, &end, 10);
+
+              if (end == from || errno != 0)
+                {
+                  return FALSE;
+                }
+              else if (*end != ';')
+                {
+                  return FALSE;
+                }
+              else
+                {
+                  /* characters XML 1.1 permits */
+                  if ((0 < l && l <= 0xD7FF) ||
+                      (0xE000 <= l && l <= 0xFFFD) ||
+                      (0x10000 <= l && l <= 0x10FFFF))
+                    {
+                      gchar buf[8];
+                      char_str (l, buf);
+                      strcpy (to, buf);
+                      to += strlen (buf) - 1;
+                      from = end;
+                    }
+                  else
+                    {
+                      return FALSE;
+                    }
+                }
+            }
+
+          else if (strncmp (from, "lt;", 3) == 0)
+            {
+              *to = '<';
+              from += 2;
+            }
+          else if (strncmp (from, "gt;", 3) == 0)
+            {
+              *to = '>';
+              from += 2;
+            }
+          else if (strncmp (from, "amp;", 4) == 0)
+            {
+              *to = '&';
+              from += 3;
+            }
+          else if (strncmp (from, "quot;", 5) == 0)
+            {
+              *to = '"';
+              from += 4;
+            }
+          else if (strncmp (from, "apos;", 5) == 0)
+            {
+              *to = '\'';
+              from += 4;
+            }
+          else
+            {
+              return FALSE;
+            }
+        }
+    }
+
+  gimp_assert (to - string->str <= string->len);
+  if (to - string->str != string->len)
+    g_string_truncate (string, to - string->str);
+
+  return TRUE;
+}
+
+gchar *
+gimp_markup_extract_text (const gchar *markup)
+{
+  GString     *string;
+  const gchar *p;
+  gboolean     in_tag = FALSE;
+
+  if (! markup)
+    return NULL;
+
+  string = g_string_new (NULL);
+
+  for (p = markup; *p; p++)
+    {
+      if (in_tag)
+        {
+          if (*p == '>')
+            in_tag = FALSE;
+        }
+      else
+        {
+          if (*p == '<')
+            in_tag = TRUE;
+          else
+            g_string_append_c (string, *p);
+        }
+    }
+
+  unescape_gstring (string);
+
+  return g_string_free (string, FALSE);
+}
+
+/**
+ * gimp_enum_get_value_name:
+ * @enum_type: Enum type
+ * @value:     Enum value
+ *
+ * Returns the value name for a given value of a given enum
+ * type. Useful to have inline in GIMP_LOG() messages for example.
+ *
+ * Returns: The value name.
+ **/
+const gchar *
+gimp_enum_get_value_name (GType enum_type,
+                          gint  value)
+{
+  const gchar *value_name = NULL;
+
+  gimp_enum_get_value (enum_type,
+                       value,
+                       &value_name,
+                       NULL /*value_nick*/,
+                       NULL /*value_desc*/,
+                       NULL /*value_help*/);
+
+  return value_name;
+}
+
+gboolean
+gimp_get_fill_params (GimpContext   *context,
+                      GimpFillType   fill_type,
+                      GimpRGB       *color,
+                      GimpPattern  **pattern,
+                      GError       **error)
+
+{
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), FALSE);
+  g_return_val_if_fail (color != NULL, FALSE);
+  g_return_val_if_fail (pattern != NULL, FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  *pattern = NULL;
+
+  switch (fill_type)
+    {
+    case GIMP_FILL_FOREGROUND:
+      gimp_context_get_foreground (context, color);
+      break;
+
+    case GIMP_FILL_BACKGROUND:
+      gimp_context_get_background (context, color);
+      break;
+
+    case GIMP_FILL_WHITE:
+      gimp_rgba_set (color, 1.0, 1.0, 1.0, GIMP_OPACITY_OPAQUE);
+      break;
+
+    case GIMP_FILL_TRANSPARENT:
+      gimp_rgba_set (color, 0.0, 0.0, 0.0, GIMP_OPACITY_TRANSPARENT);
+      break;
+
+    case GIMP_FILL_PATTERN:
+      *pattern = gimp_context_get_pattern (context);
+
+      if (! *pattern)
+        {
+          g_set_error_literal (error, GIMP_ERROR, GIMP_FAILED,
+                               _("No patterns available for this operation."));
+
+          /*  fall back to BG fill  */
+          gimp_context_get_background (context, color);
+
+          return FALSE;
+        }
+      break;
+
+    default:
+      g_warning ("%s: invalid fill_type %d", G_STRFUNC, fill_type);
+      return FALSE;
+    }
+
+  return TRUE;
+}
+
+/**
+ * gimp_constrain_line:
+ * @start_x:
+ * @start_y:
+ * @end_x:
+ * @end_y:
+ * @n_snap_lines: Number evenly disributed lines to snap to.
+ * @offset_angle: The angle by which to offset the lines, in degrees.
+ * @xres:         The horizontal resolution.
+ * @yres:         The vertical resolution.
+ *
+ * Projects a line onto the specified subset of evenly radially
+ * distributed lines. @n_lines of 2 makes the line snap horizontally
+ * or vertically. @n_lines of 4 snaps on 45 degree steps. @n_lines of
+ * 12 on 15 degree steps. etc.
+ **/
+void
+gimp_constrain_line (gdouble  start_x,
+                     gdouble  start_y,
+                     gdouble *end_x,
+                     gdouble *end_y,
+                     gint     n_snap_lines,
+                     gdouble  offset_angle,
+                     gdouble  xres,
+                     gdouble  yres)
+{
+  GimpVector2 diff;
+  GimpVector2 dir;
+  gdouble     angle;
+
+  offset_angle *= G_PI / 180.0;
+
+  diff.x = (*end_x - start_x) / xres;
+  diff.y = (*end_y - start_y) / yres;
+
+  angle = (atan2 (diff.y, diff.x) - offset_angle) * n_snap_lines / G_PI;
+  angle = RINT (angle) * G_PI / n_snap_lines + offset_angle;
+
+  dir.x = cos (angle);
+  dir.y = sin (angle);
+
+  gimp_vector2_mul (&dir, gimp_vector2_inner_product (&dir, &diff));
+
+  *end_x = start_x + dir.x * xres;
+  *end_y = start_y + dir.y * yres;
+}
+
+gint
+gimp_file_compare (GFile *file1,
+                   GFile *file2)
+{
+  if (g_file_equal (file1, file2))
+    {
+      return 0;
+    }
+  else
+    {
+      gchar *uri1   = g_file_get_uri (file1);
+      gchar *uri2   = g_file_get_uri (file2);
+      gint   result = strcmp (uri1, uri2);
+
+      g_free (uri1);
+      g_free (uri2);
+
+      return result;
+    }
+}
+
+static inline gboolean
+is_script (const gchar *filename)
+{
+#ifdef G_OS_WIN32
+  /* On Windows there is no concept like the Unix executable flag.
+   * There is a weak emulation provided by the MS C Runtime using file
+   * extensions (com, exe, cmd, bat). This needs to be extended to
+   * treat scripts (Python, Perl, ...) as executables, too. We use the
+   * PATHEXT variable, which is also used by cmd.exe.
+   */
+  static gchar **exts = NULL;
+
+  const gchar   *ext = strrchr (filename, '.');
+  const gchar   *pathext;
+  gint           i;
+
+  if (exts == NULL)
+    {
+      pathext = g_getenv ("PATHEXT");
+      if (pathext != NULL)
+        {
+          exts = g_strsplit (pathext, G_SEARCHPATH_SEPARATOR_S, 100);
+        }
+      else
+        {
+          exts = g_new (gchar *, 1);
+          exts[0] = NULL;
+        }
+    }
+
+  for (i = 0; exts[i]; i++)
+    {
+      if (g_ascii_strcasecmp (ext, exts[i]) == 0)
+        return TRUE;
+    }
+#endif /* G_OS_WIN32 */
+
+  return FALSE;
+}
+
+gboolean
+gimp_file_is_executable (GFile *file)
+{
+  GFileInfo *info;
+  gboolean   executable = FALSE;
+
+  g_return_val_if_fail (G_IS_FILE (file), FALSE);
+
+  info = g_file_query_info (file,
+                            G_FILE_ATTRIBUTE_STANDARD_NAME ","
+                            G_FILE_ATTRIBUTE_STANDARD_TYPE ","
+                            G_FILE_ATTRIBUTE_ACCESS_CAN_EXECUTE ",",
+                            G_FILE_QUERY_INFO_NONE,
+                            NULL, NULL);
+
+  if (info)
+    {
+      GFileType    file_type = g_file_info_get_file_type (info);
+      const gchar *filename  = g_file_info_get_name (info);
+
+      if (file_type == G_FILE_TYPE_REGULAR &&
+          (g_file_info_get_attribute_boolean (info,
+                                              G_FILE_ATTRIBUTE_ACCESS_CAN_EXECUTE) ||
+           is_script (filename)))
+        {
+          executable = TRUE;
+        }
+
+      g_object_unref (info);
+    }
+
+  return executable;
+}
+
+/**
+ * gimp_file_get_extension:
+ * @file: A #GFile
+ *
+ * Returns @file's extension (including the .), or NULL if there is no
+ * extension. Note that this function handles compressed files too,
+ * e.g. for "file.png.gz" it will return ".png.gz".
+ *
+ * Returns: The @file's extension. Free with g_free() when no longer needed.
+ **/
+gchar *
+gimp_file_get_extension (GFile *file)
+{
+  gchar *uri;
+  gint   uri_len;
+  gchar *ext = NULL;
+  gint   search_len;
+
+  g_return_val_if_fail (G_IS_FILE (file), NULL);
+
+  uri     = g_file_get_uri (file);
+  uri_len = strlen (uri);
+
+  if (g_str_has_suffix (uri, ".gz"))
+    search_len = uri_len - 3;
+  else if (g_str_has_suffix (uri, ".bz2"))
+    search_len = uri_len - 4;
+  else if (g_str_has_suffix (uri, ".xz"))
+    search_len = uri_len - 3;
+  else
+    search_len = uri_len;
+
+  ext = g_strrstr_len (uri, search_len, ".");
+
+  if (ext)
+    ext = g_strdup (ext);
+
+  g_free (uri);
+
+  return ext;
+}
+
+GFile *
+gimp_file_with_new_extension (GFile *file,
+                              GFile *ext_file)
+{
+  gchar *uri;
+  gchar *file_ext;
+  gint   file_ext_len = 0;
+  gchar *ext_file_ext = NULL;
+  gchar *uri_without_ext;
+  gchar *new_uri;
+  GFile *ret;
+
+  g_return_val_if_fail (G_IS_FILE (file), NULL);
+  g_return_val_if_fail (ext_file == NULL || G_IS_FILE (ext_file), NULL);
+
+  uri      = g_file_get_uri (file);
+  file_ext = gimp_file_get_extension (file);
+
+  if (file_ext)
+    {
+      file_ext_len = strlen (file_ext);
+      g_free (file_ext);
+    }
+
+  if (ext_file)
+    ext_file_ext = gimp_file_get_extension (ext_file);
+
+  uri_without_ext = g_strndup (uri, strlen (uri) - file_ext_len);
+
+  g_free (uri);
+
+  new_uri = g_strconcat (uri_without_ext, ext_file_ext, NULL);
+
+  ret = g_file_new_for_uri (new_uri);
+
+  g_free (ext_file_ext);
+  g_free (uri_without_ext);
+  g_free (new_uri);
+
+  return ret;
+}
+
+gchar *
+gimp_data_input_stream_read_line_always (GDataInputStream  *stream,
+                                         gsize             *length,
+                                         GCancellable      *cancellable,
+                                         GError           **error)
+{
+  GError *temp_error = NULL;
+  gchar  *result;
+
+  g_return_val_if_fail (G_IS_DATA_INPUT_STREAM (stream), NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, NULL);
+
+  if (! error)
+    error = &temp_error;
+
+  result = g_data_input_stream_read_line (stream, length, cancellable, error);
+
+  if (! result && ! *error)
+    {
+      result = g_strdup ("");
+
+      if (length) *length = 0;
+    }
+
+  g_clear_error (&temp_error);
+
+  return result;
+}
+
+gboolean
+gimp_ascii_strtoi (const gchar  *nptr,
+                   gchar       **endptr,
+                   gint          base,
+                   gint         *result)
+{
+  gchar  *temp_endptr;
+  gint64  temp_result;
+
+  g_return_val_if_fail (nptr != NULL, FALSE);
+  g_return_val_if_fail (base == 0 || (base >= 2 && base <= 36), FALSE);
+
+  if (! endptr)
+    endptr = &temp_endptr;
+
+  temp_result = g_ascii_strtoll (nptr, endptr, base);
+
+  if (*endptr == nptr || errno == ERANGE ||
+      temp_result < G_MININT || temp_result > G_MAXINT)
+    {
+      errno = 0;
+
+      return FALSE;
+    }
+
+  if (result) *result = temp_result;
+
+  return TRUE;
+}
+
+gboolean
+gimp_ascii_strtod (const gchar  *nptr,
+                   gchar       **endptr,
+                   gdouble      *result)
+{
+  gchar   *temp_endptr;
+  gdouble  temp_result;
+
+  g_return_val_if_fail (nptr != NULL, FALSE);
+
+  if (! endptr)
+    endptr = &temp_endptr;
+
+  temp_result = g_ascii_strtod (nptr, endptr);
+
+  if (*endptr == nptr || errno == ERANGE)
+    {
+      errno = 0;
+
+      return FALSE;
+    }
+
+  if (result) *result = temp_result;
+
+  return TRUE;
+}
+
+gint
+gimp_g_list_compare (GList *list1,
+                     GList *list2)
+{
+  while (list1 && list2)
+    {
+      if (list1->data < list2->data)
+        return -1;
+      else if (list1->data > list2->data)
+        return +1;
+
+      list1 = g_list_next (list1);
+      list2 = g_list_next (list2);
+    }
+
+  if (! list1)
+    return -1;
+  else if (! list2)
+    return +1;
+
+  return 0;
+}
+
+typedef struct
+{
+  gint              ref_count;
+
+  GimpAsync        *async;
+  gint              idle_id;
+
+  GimpRunAsyncFunc  func;
+  gpointer          user_data;
+  GDestroyNotify    user_data_destroy_func;
+} GimpIdleRunAsyncData;
+
+static GimpIdleRunAsyncData *
+gimp_idle_run_async_data_new (void)
+{
+  GimpIdleRunAsyncData *data;
+
+  data = g_slice_new0 (GimpIdleRunAsyncData);
+
+  data->ref_count = 1;
+
+  return data;
+}
+
+static void
+gimp_idle_run_async_data_inc_ref (GimpIdleRunAsyncData *data)
+{
+  data->ref_count++;
+}
+
+static void
+gimp_idle_run_async_data_dec_ref (GimpIdleRunAsyncData *data)
+{
+  data->ref_count--;
+
+  if (data->ref_count == 0)
+    {
+      g_signal_handlers_disconnect_by_data (data->async, data);
+
+      if (! gimp_async_is_stopped (data->async))
+        gimp_async_abort (data->async);
+
+      g_object_unref (data->async);
+
+      if (data->user_data && data->user_data_destroy_func)
+        data->user_data_destroy_func (data->user_data);
+
+      g_slice_free (GimpIdleRunAsyncData, data);
+    }
+}
+
+static void
+gimp_idle_run_async_cancel (GimpAsync            *async,
+                            GimpIdleRunAsyncData *data)
+{
+  gimp_idle_run_async_data_inc_ref (data);
+
+  if (data->idle_id)
+    {
+      g_source_remove (data->idle_id);
+
+      data->idle_id = 0;
+    }
+
+  gimp_idle_run_async_data_dec_ref (data);
+}
+
+static void
+gimp_idle_run_async_waiting (GimpAsync            *async,
+                             GimpIdleRunAsyncData *data)
+{
+  gimp_idle_run_async_data_inc_ref (data);
+
+  if (data->idle_id)
+    {
+      g_source_remove (data->idle_id);
+
+      data->idle_id = 0;
+    }
+
+  g_signal_handlers_block_by_func (data->async,
+                                   gimp_idle_run_async_cancel,
+                                   data);
+
+  while (! gimp_async_is_stopped (data->async))
+    data->func (data->async, data->user_data);
+
+  g_signal_handlers_unblock_by_func (data->async,
+                                     gimp_idle_run_async_cancel,
+                                     data);
+
+  data->user_data = NULL;
+
+  gimp_idle_run_async_data_dec_ref (data);
+}
+
+static gboolean
+gimp_idle_run_async_idle (GimpIdleRunAsyncData *data)
+{
+  gimp_idle_run_async_data_inc_ref (data);
+
+  g_signal_handlers_block_by_func (data->async,
+                                   gimp_idle_run_async_cancel,
+                                   data);
+
+  data->func (data->async, data->user_data);
+
+  g_signal_handlers_unblock_by_func (data->async,
+                                     gimp_idle_run_async_cancel,
+                                     data);
+
+  if (gimp_async_is_stopped (data->async))
+    {
+      data->user_data = NULL;
+
+      gimp_idle_run_async_data_dec_ref (data);
+
+      return G_SOURCE_REMOVE;
+    }
+
+  gimp_idle_run_async_data_dec_ref (data);
+
+  return G_SOURCE_CONTINUE;
+}
+
+GimpAsync *
+gimp_idle_run_async (GimpRunAsyncFunc func,
+                     gpointer         user_data)
+{
+  return gimp_idle_run_async_full (G_PRIORITY_DEFAULT_IDLE, func,
+                                   user_data, NULL);
+}
+
+GimpAsync *
+gimp_idle_run_async_full (gint             priority,
+                          GimpRunAsyncFunc func,
+                          gpointer         user_data,
+                          GDestroyNotify   user_data_destroy_func)
+{
+  GimpIdleRunAsyncData *data;
+
+  g_return_val_if_fail (func != NULL, NULL);
+
+  data = gimp_idle_run_async_data_new ();
+
+  data->func                   = func;
+  data->user_data              = user_data;
+  data->user_data_destroy_func = user_data_destroy_func;
+
+  data->async = gimp_async_new ();
+
+  g_signal_connect (data->async, "cancel",
+                    G_CALLBACK (gimp_idle_run_async_cancel),
+                    data);
+  g_signal_connect (data->async, "waiting",
+                    G_CALLBACK (gimp_idle_run_async_waiting),
+                    data);
+
+  data->idle_id = g_idle_add_full (
+    priority,
+    (GSourceFunc) gimp_idle_run_async_idle,
+    data,
+    (GDestroyNotify) gimp_idle_run_async_data_dec_ref);
+
+  return g_object_ref (data->async);
+}
+
+
+/*  debug stuff  */
+
+#include "gegl/gimp-babl.h"
+#include "gimpimage.h"
+#include "gimplayer.h"
+#include "gimplayer-new.h"
+
+GimpImage *
+gimp_create_image_from_buffer (Gimp        *gimp,
+                               GeglBuffer  *buffer,
+                               const gchar *image_name)
+{
+  GimpImage  *image;
+  GimpLayer  *layer;
+  const Babl *format;
+
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+  g_return_val_if_fail (GEGL_IS_BUFFER (buffer), NULL);
+
+  if (! image_name)
+    image_name = "Debug Image";
+
+  format = gegl_buffer_get_format (buffer);
+
+  image = gimp_create_image (gimp,
+                             gegl_buffer_get_width  (buffer),
+                             gegl_buffer_get_height (buffer),
+                             gimp_babl_format_get_base_type (format),
+                             gimp_babl_format_get_precision (format),
+                             FALSE);
+
+  layer = gimp_layer_new_from_gegl_buffer (buffer, image, format,
+                                           image_name,
+                                           GIMP_OPACITY_OPAQUE,
+                                           GIMP_LAYER_MODE_NORMAL,
+                                           NULL /* same image */);
+  gimp_image_add_layer (image, layer, NULL, -1, FALSE);
+
+  gimp_create_display (gimp, image, GIMP_UNIT_PIXEL, 1.0, NULL, 0);
+
+  /* unref the image unconditionally, even when no display was created */
+  g_object_add_weak_pointer (G_OBJECT (image), (gpointer) &image);
+  g_object_unref (image);
+
+  return image;
+}
diff --git a/app/core/gimp-utils.h b/app/core/gimp-utils.h
new file mode 100644
index 0000000..8373de7
--- /dev/null
+++ b/app/core/gimp-utils.h
@@ -0,0 +1,116 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __APP_GIMP_UTILS_H__
+#define __APP_GIMP_UTILS_H__
+
+
+#define GIMP_TIMER_START() \
+  { GTimer *_timer = g_timer_new ();
+
+#define GIMP_TIMER_END(message) \
+  g_printerr ("%s: %s took %0.4f seconds\n", \
+              G_STRFUNC, message, g_timer_elapsed (_timer, NULL)); \
+  g_timer_destroy (_timer); }
+
+
+#define MIN4(a,b,c,d) MIN (MIN ((a), (b)), MIN ((c), (d)))
+#define MAX4(a,b,c,d) MAX (MAX ((a), (b)), MAX ((c), (d)))
+
+
+gint         gimp_get_pid                          (void);
+guint64      gimp_get_physical_memory_size         (void);
+gchar      * gimp_get_default_language             (const gchar     *category);
+GimpUnit     gimp_get_default_unit                 (void);
+
+gchar     ** gimp_properties_append                (GType            object_type,
+                                                    gint            *n_properties,
+                                                    gchar          **names,
+                                                    GValue         **values,
+                                                    ...) G_GNUC_NULL_TERMINATED;
+gchar     ** gimp_properties_append_valist         (GType            object_type,
+                                                    gint            *n_properties,
+                                                    gchar          **names,
+                                                    GValue         **values,
+                                                    va_list          args);
+void         gimp_properties_free                  (gint             n_properties,
+                                                    gchar          **names,
+                                                    GValue          *values);
+
+gchar      * gimp_markup_extract_text              (const gchar     *markup);
+
+const gchar* gimp_enum_get_value_name              (GType            enum_type,
+                                                    gint             value);
+
+gboolean     gimp_get_fill_params                  (GimpContext      *context,
+                                                    GimpFillType      fill_type,
+                                                    GimpRGB          *color,
+                                                    GimpPattern     **pattern,
+                                                    GError          **error);
+
+/* Common values for the n_snap_lines parameter of
+ * gimp_constrain_line.
+ */
+#define GIMP_CONSTRAIN_LINE_90_DEGREES 2
+#define GIMP_CONSTRAIN_LINE_45_DEGREES 4
+#define GIMP_CONSTRAIN_LINE_15_DEGREES 12
+
+void         gimp_constrain_line                   (gdouble          start_x,
+                                                    gdouble          start_y,
+                                                    gdouble         *end_x,
+                                                    gdouble         *end_y,
+                                                    gint             n_snap_lines,
+                                                    gdouble          offset_angle,
+                                                    gdouble          xres,
+                                                    gdouble          yres);
+
+gint         gimp_file_compare                     (GFile           *file1,
+                                                    GFile           *file2);
+gboolean     gimp_file_is_executable               (GFile           *file);
+gchar      * gimp_file_get_extension               (GFile           *file);
+GFile      * gimp_file_with_new_extension          (GFile           *file,
+                                                    GFile           *ext_file);
+
+gchar      * gimp_data_input_stream_read_line_always (GDataInputStream  *stream,
+                                                      gsize             *length,
+                                                      GCancellable      *cancellable,
+                                                      GError           **error);
+
+gboolean     gimp_ascii_strtoi                     (const gchar     *nptr,
+                                                    gchar          **endptr,
+                                                    gint             base,
+                                                    gint            *result);
+gboolean     gimp_ascii_strtod                     (const gchar     *nptr,
+                                                    gchar          **endptr,
+                                                    gdouble         *result);
+
+gint         gimp_g_list_compare                   (GList           *list1,
+                                                    GList           *list2);
+
+GimpAsync  * gimp_idle_run_async                   (GimpRunAsyncFunc func,
+                                                    gpointer         user_data);
+GimpAsync  * gimp_idle_run_async_full              (gint             priority,
+                                                    GimpRunAsyncFunc func,
+                                                    gpointer         user_data,
+                                                    GDestroyNotify   user_data_destroy_func);
+
+GimpImage  * gimp_create_image_from_buffer         (Gimp            *gimp,
+                                                    GeglBuffer      *buffer,
+                                                    const gchar     *image_name);
+
+
+#endif /* __APP_GIMP_UTILS_H__ */
diff --git a/app/core/gimp.c b/app/core/gimp.c
new file mode 100644
index 0000000..ede44fe
--- /dev/null
+++ b/app/core/gimp.c
@@ -0,0 +1,1224 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-2002 Spencer Kimball, Peter Mattis, and others
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h> /* strlen */
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpconfig/gimpconfig.h"
+
+#include "core-types.h"
+
+#include "config/gimprc.h"
+
+#include "gegl/gimp-babl.h"
+
+#include "pdb/gimppdb.h"
+#include "pdb/gimp-pdb-compat.h"
+#include "pdb/internal-procs.h"
+
+#include "plug-in/gimppluginmanager.h"
+#include "plug-in/gimppluginmanager-restore.h"
+
+#include "paint/gimp-paint.h"
+
+#include "xcf/xcf.h"
+#include "file-data/file-data.h"
+
+#include "gimp.h"
+#include "gimp-contexts.h"
+#include "gimp-data-factories.h"
+#include "gimp-filter-history.h"
+#include "gimp-memsize.h"
+#include "gimp-modules.h"
+#include "gimp-parasites.h"
+#include "gimp-templates.h"
+#include "gimp-units.h"
+#include "gimp-utils.h"
+#include "gimpbrush.h"
+#include "gimpbuffer.h"
+#include "gimpcontext.h"
+#include "gimpdynamics.h"
+#include "gimpdocumentlist.h"
+#include "gimpgradient.h"
+#include "gimpidtable.h"
+#include "gimpimage.h"
+#include "gimpimagefile.h"
+#include "gimplist.h"
+#include "gimpmarshal.h"
+#include "gimpmybrush.h"
+#include "gimppalette.h"
+#include "gimpparasitelist.h"
+#include "gimppattern.h"
+#include "gimptemplate.h"
+#include "gimptoolinfo.h"
+#include "gimptreeproxy.h"
+
+#include "gimp-intl.h"
+
+
+enum
+{
+  INITIALIZE,
+  RESTORE,
+  EXIT,
+  CLIPBOARD_CHANGED,
+  FILTER_HISTORY_CHANGED,
+  IMAGE_OPENED,
+  LAST_SIGNAL
+};
+
+enum
+{
+  PROP_0,
+  PROP_VERBOSE
+};
+
+
+static void      gimp_constructed          (GObject           *object);
+static void      gimp_set_property         (GObject           *object,
+                                            guint              property_id,
+                                            const GValue      *value,
+                                            GParamSpec        *pspec);
+static void      gimp_get_property         (GObject           *object,
+                                            guint              property_id,
+                                            GValue            *value,
+                                            GParamSpec        *pspec);
+static void      gimp_dispose              (GObject           *object);
+static void      gimp_finalize             (GObject           *object);
+
+static gint64    gimp_get_memsize          (GimpObject        *object,
+                                            gint64            *gui_size);
+
+static void      gimp_real_initialize      (Gimp              *gimp,
+                                            GimpInitStatusFunc status_callback);
+static void      gimp_real_restore         (Gimp              *gimp,
+                                            GimpInitStatusFunc status_callback);
+static gboolean  gimp_real_exit            (Gimp              *gimp,
+                                            gboolean           force);
+
+static void      gimp_global_config_notify (GObject           *global_config,
+                                            GParamSpec        *param_spec,
+                                            GObject           *edit_config);
+static void      gimp_edit_config_notify   (GObject           *edit_config,
+                                            GParamSpec        *param_spec,
+                                            GObject           *global_config);
+
+
+G_DEFINE_TYPE (Gimp, gimp, GIMP_TYPE_OBJECT)
+
+#define parent_class gimp_parent_class
+
+static guint gimp_signals[LAST_SIGNAL] = { 0, };
+
+
+static void
+gimp_class_init (GimpClass *klass)
+{
+  GObjectClass    *object_class      = G_OBJECT_CLASS (klass);
+  GimpObjectClass *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+
+  gimp_signals[INITIALIZE] =
+    g_signal_new ("initialize",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_LAST,
+                  G_STRUCT_OFFSET (GimpClass, initialize),
+                  NULL, NULL,
+                  gimp_marshal_VOID__POINTER,
+                  G_TYPE_NONE, 1,
+                  G_TYPE_POINTER);
+
+  gimp_signals[RESTORE] =
+    g_signal_new ("restore",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_LAST,
+                  G_STRUCT_OFFSET (GimpClass, restore),
+                  NULL, NULL,
+                  gimp_marshal_VOID__POINTER,
+                  G_TYPE_NONE, 1,
+                  G_TYPE_POINTER);
+
+  gimp_signals[EXIT] =
+    g_signal_new ("exit",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_LAST,
+                  G_STRUCT_OFFSET (GimpClass, exit),
+                  g_signal_accumulator_true_handled, NULL,
+                  gimp_marshal_BOOLEAN__BOOLEAN,
+                  G_TYPE_BOOLEAN, 1,
+                  G_TYPE_BOOLEAN);
+
+  gimp_signals[CLIPBOARD_CHANGED] =
+    g_signal_new ("clipboard-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_LAST,
+                  G_STRUCT_OFFSET (GimpClass, clipboard_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  gimp_signals[FILTER_HISTORY_CHANGED] =
+    g_signal_new ("filter-history-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_LAST,
+                  G_STRUCT_OFFSET (GimpClass,
+                                   filter_history_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  gimp_signals[IMAGE_OPENED] =
+    g_signal_new ("image-opened",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_LAST,
+                  G_STRUCT_OFFSET (GimpClass, image_opened),
+                  NULL, NULL,
+                  gimp_marshal_VOID__OBJECT,
+                  G_TYPE_NONE, 1, G_TYPE_FILE);
+
+  object_class->constructed      = gimp_constructed;
+  object_class->set_property     = gimp_set_property;
+  object_class->get_property     = gimp_get_property;
+  object_class->dispose          = gimp_dispose;
+  object_class->finalize         = gimp_finalize;
+
+  gimp_object_class->get_memsize = gimp_get_memsize;
+
+  klass->initialize              = gimp_real_initialize;
+  klass->restore                 = gimp_real_restore;
+  klass->exit                    = gimp_real_exit;
+  klass->clipboard_changed       = NULL;
+
+  g_object_class_install_property (object_class, PROP_VERBOSE,
+                                   g_param_spec_boolean ("verbose", NULL, NULL,
+                                                         FALSE,
+                                                         GIMP_PARAM_READWRITE |
+                                                         G_PARAM_CONSTRUCT_ONLY));
+}
+
+static void
+gimp_init (Gimp *gimp)
+{
+  gimp->be_verbose       = FALSE;
+  gimp->no_data          = FALSE;
+  gimp->no_interface     = FALSE;
+  gimp->show_gui         = TRUE;
+  gimp->use_shm          = FALSE;
+  gimp->use_cpu_accel    = TRUE;
+  gimp->message_handler  = GIMP_CONSOLE;
+  gimp->show_playground  = FALSE;
+  gimp->stack_trace_mode = GIMP_STACK_TRACE_NEVER;
+  gimp->pdb_compat_mode  = GIMP_PDB_COMPAT_OFF;
+
+  gimp_gui_init (gimp);
+
+  gimp->parasites = gimp_parasite_list_new ();
+
+  gimp_units_init (gimp);
+
+  gimp->images = gimp_list_new_weak (GIMP_TYPE_IMAGE, FALSE);
+  gimp_object_set_static_name (GIMP_OBJECT (gimp->images), "images");
+
+  gimp->next_guide_ID        = 1;
+  gimp->next_sample_point_ID = 1;
+  gimp->image_table          = gimp_id_table_new ();
+  gimp->item_table           = gimp_id_table_new ();
+
+  gimp->displays = g_object_new (GIMP_TYPE_LIST,
+                                 "children-type", GIMP_TYPE_OBJECT,
+                                 "policy",        GIMP_CONTAINER_POLICY_WEAK,
+                                 "append",        TRUE,
+                                 NULL);
+  gimp_object_set_static_name (GIMP_OBJECT (gimp->displays), "displays");
+  gimp->next_display_ID = 1;
+
+  gimp->named_buffers = gimp_list_new (GIMP_TYPE_BUFFER, TRUE);
+  gimp_object_set_static_name (GIMP_OBJECT (gimp->named_buffers),
+                               "named buffers");
+
+  gimp_data_factories_init (gimp);
+
+  gimp->tool_info_list = g_object_new (GIMP_TYPE_LIST,
+                                       "children-type", GIMP_TYPE_TOOL_INFO,
+                                       "append",        TRUE,
+                                       NULL);
+  gimp_object_set_static_name (GIMP_OBJECT (gimp->tool_info_list),
+                               "tool infos");
+
+  gimp->tool_item_list = g_object_new (GIMP_TYPE_LIST,
+                                       "children-type", GIMP_TYPE_TOOL_ITEM,
+                                       "append",        TRUE,
+                                       NULL);
+  gimp_object_set_static_name (GIMP_OBJECT (gimp->tool_item_list),
+                               "tool items");
+
+  gimp->tool_item_ui_list = gimp_tree_proxy_new_for_container (
+    gimp->tool_item_list);
+  gimp_object_set_static_name (GIMP_OBJECT (gimp->tool_item_ui_list),
+                               "ui tool items");
+
+  gimp->documents = gimp_document_list_new (gimp);
+
+  gimp->templates = gimp_list_new (GIMP_TYPE_TEMPLATE, TRUE);
+  gimp_object_set_static_name (GIMP_OBJECT (gimp->templates), "templates");
+}
+
+static void
+gimp_constructed (GObject *object)
+{
+  Gimp *gimp = GIMP (object);
+
+  G_OBJECT_CLASS (parent_class)->constructed (object);
+
+  gimp_modules_init (gimp);
+
+  gimp_paint_init (gimp);
+
+  gimp->plug_in_manager = gimp_plug_in_manager_new (gimp);
+  gimp->pdb             = gimp_pdb_new (gimp);
+
+  xcf_init (gimp);
+  file_data_init (gimp);
+
+  /*  create user and default context  */
+  gimp_contexts_init (gimp);
+}
+
+static void
+gimp_set_property (GObject           *object,
+                   guint              property_id,
+                   const GValue      *value,
+                   GParamSpec        *pspec)
+{
+  Gimp *gimp = GIMP (object);
+
+  switch (property_id)
+    {
+    case PROP_VERBOSE:
+      gimp->be_verbose = g_value_get_boolean (value);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_get_property (GObject    *object,
+                   guint       property_id,
+                   GValue     *value,
+                   GParamSpec *pspec)
+{
+  Gimp *gimp = GIMP (object);
+
+  switch (property_id)
+    {
+    case PROP_VERBOSE:
+      g_value_set_boolean (value, gimp->be_verbose);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_dispose (GObject *object)
+{
+  Gimp *gimp = GIMP (object);
+
+  if (gimp->be_verbose)
+    g_print ("EXIT: %s\n", G_STRFUNC);
+
+  gimp_data_factories_clear (gimp);
+
+  gimp_filter_history_clear (gimp);
+
+  g_clear_object (&gimp->edit_config);
+  g_clear_object (&gimp->config);
+
+  gimp_contexts_exit (gimp);
+
+  g_clear_object (&gimp->image_new_last_template);
+
+  G_OBJECT_CLASS (parent_class)->dispose (object);
+}
+
+static void
+gimp_finalize (GObject *object)
+{
+  Gimp  *gimp      = GIMP (object);
+  GList *standards = NULL;
+
+  if (gimp->be_verbose)
+    g_print ("EXIT: %s\n", G_STRFUNC);
+
+  standards = g_list_prepend (standards,
+                              gimp_brush_get_standard (gimp->user_context));
+  standards = g_list_prepend (standards,
+                              gimp_dynamics_get_standard (gimp->user_context));
+  standards = g_list_prepend (standards,
+                              gimp_mybrush_get_standard (gimp->user_context));
+  standards = g_list_prepend (standards,
+                              gimp_pattern_get_standard (gimp->user_context));
+  standards = g_list_prepend (standards,
+                              gimp_gradient_get_standard (gimp->user_context));
+  standards = g_list_prepend (standards,
+                              gimp_palette_get_standard (gimp->user_context));
+
+  g_clear_object (&gimp->templates);
+  g_clear_object (&gimp->documents);
+
+  gimp_tool_info_set_standard (gimp, NULL);
+
+  g_clear_object (&gimp->tool_item_list);
+  g_clear_object (&gimp->tool_item_ui_list);
+
+  if (gimp->tool_info_list)
+    {
+      gimp_container_foreach (gimp->tool_info_list,
+                              (GFunc) g_object_run_dispose, NULL);
+      g_clear_object (&gimp->tool_info_list);
+    }
+
+  file_data_exit (gimp);
+  xcf_exit (gimp);
+
+  g_clear_object (&gimp->pdb);
+
+  gimp_data_factories_exit (gimp);
+
+  g_clear_object (&gimp->named_buffers);
+  g_clear_object (&gimp->clipboard_buffer);
+  g_clear_object (&gimp->clipboard_image);
+  g_clear_object (&gimp->displays);
+  g_clear_object (&gimp->item_table);
+  g_clear_object (&gimp->image_table);
+  g_clear_object (&gimp->images);
+  g_clear_object (&gimp->plug_in_manager);
+
+  if (gimp->module_db)
+    gimp_modules_exit (gimp);
+
+  gimp_paint_exit (gimp);
+
+  g_clear_object (&gimp->parasites);
+  g_clear_object (&gimp->default_folder);
+
+  g_clear_pointer (&gimp->session_name, g_free);
+
+  if (gimp->context_list)
+    {
+      GList *list;
+
+      g_warning ("%s: list of contexts not empty upon exit (%d contexts left)\n",
+                 G_STRFUNC, g_list_length (gimp->context_list));
+
+      for (list = gimp->context_list; list; list = g_list_next (list))
+        g_printerr ("stale context: %s\n", gimp_object_get_name (list->data));
+
+      g_list_free (gimp->context_list);
+      gimp->context_list = NULL;
+    }
+
+  g_list_foreach (standards, (GFunc) g_object_unref, NULL);
+  g_list_free (standards);
+
+  gimp_units_exit (gimp);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static gint64
+gimp_get_memsize (GimpObject *object,
+                  gint64     *gui_size)
+{
+  Gimp   *gimp    = GIMP (object);
+  gint64  memsize = 0;
+
+  memsize += gimp_g_list_get_memsize (gimp->user_units, 0 /* FIXME */);
+
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (gimp->parasites),
+                                      gui_size);
+
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (gimp->paint_info_list),
+                                      gui_size);
+
+  memsize += gimp_g_object_get_memsize (G_OBJECT (gimp->module_db));
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (gimp->plug_in_manager),
+                                      gui_size);
+
+  memsize += gimp_g_list_get_memsize_foreach (gimp->filter_history,
+                                              (GimpMemsizeFunc)
+                                              gimp_object_get_memsize,
+                                              gui_size);
+
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (gimp->image_table), 0);
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (gimp->item_table),  0);
+
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (gimp->displays), gui_size);
+
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (gimp->clipboard_image),
+                                      gui_size);
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (gimp->clipboard_buffer),
+                                      gui_size);
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (gimp->named_buffers),
+                                      gui_size);
+
+  memsize += gimp_data_factories_get_memsize (gimp, gui_size);
+
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (gimp->pdb), gui_size);
+
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (gimp->tool_info_list),
+                                      gui_size);
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (gimp->standard_tool_info),
+                                      gui_size);
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (gimp->documents),
+                                      gui_size);
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (gimp->templates),
+                                      gui_size);
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (gimp->image_new_last_template),
+                                      gui_size);
+
+  memsize += gimp_g_list_get_memsize (gimp->context_list, 0);
+
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (gimp->default_context),
+                                      gui_size);
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (gimp->user_context),
+                                      gui_size);
+
+  return memsize + GIMP_OBJECT_CLASS (parent_class)->get_memsize (object,
+                                                                  gui_size);
+}
+
+static void
+gimp_real_initialize (Gimp               *gimp,
+                      GimpInitStatusFunc  status_callback)
+{
+  if (gimp->be_verbose)
+    g_print ("INIT: %s\n", G_STRFUNC);
+
+  status_callback (_("Initialization"), NULL, 0.0);
+
+  /*  set the last values used to default values  */
+  gimp->image_new_last_template =
+    gimp_config_duplicate (GIMP_CONFIG (gimp->config->default_image));
+
+  /*  add data objects that need the user context  */
+  gimp_data_factories_add_builtin (gimp);
+
+  /*  register all internal procedures  */
+  status_callback (NULL, _("Internal Procedures"), 0.2);
+  internal_procs_init (gimp->pdb);
+  gimp_pdb_compat_procs_register (gimp->pdb, gimp->pdb_compat_mode);
+
+  gimp_plug_in_manager_initialize (gimp->plug_in_manager, status_callback);
+
+  status_callback (NULL, "", 1.0);
+}
+
+static void
+gimp_real_restore (Gimp               *gimp,
+                   GimpInitStatusFunc  status_callback)
+{
+  if (gimp->be_verbose)
+    g_print ("INIT: %s\n", G_STRFUNC);
+
+  gimp_plug_in_manager_restore (gimp->plug_in_manager,
+                                gimp_get_user_context (gimp), status_callback);
+
+  /*  initialize babl fishes  */
+  status_callback (_("Initialization"), "Babl Fishes", 0.0);
+  gimp_babl_init_fishes (status_callback);
+
+  gimp->restored = TRUE;
+}
+
+static gboolean
+gimp_real_exit (Gimp     *gimp,
+                gboolean  force)
+{
+  if (gimp->be_verbose)
+    g_print ("EXIT: %s\n", G_STRFUNC);
+
+  gimp_plug_in_manager_exit (gimp->plug_in_manager);
+  gimp_modules_unload (gimp);
+
+  gimp_data_factories_save (gimp);
+
+  gimp_templates_save (gimp);
+  gimp_parasiterc_save (gimp);
+  gimp_unitrc_save (gimp);
+
+  return FALSE; /* continue exiting */
+}
+
+Gimp *
+gimp_new (const gchar       *name,
+          const gchar       *session_name,
+          GFile             *default_folder,
+          gboolean           be_verbose,
+          gboolean           no_data,
+          gboolean           no_fonts,
+          gboolean           no_interface,
+          gboolean           use_shm,
+          gboolean           use_cpu_accel,
+          gboolean           console_messages,
+          gboolean           show_playground,
+          gboolean           show_debug_menu,
+          GimpStackTraceMode stack_trace_mode,
+          GimpPDBCompatMode  pdb_compat_mode)
+{
+  Gimp *gimp;
+
+  g_return_val_if_fail (name != NULL, NULL);
+
+  gimp = g_object_new (GIMP_TYPE_GIMP,
+                       "name",    name,
+                       "verbose", be_verbose ? TRUE : FALSE,
+                       NULL);
+
+  if (default_folder)
+    gimp->default_folder = g_object_ref (default_folder);
+
+  gimp->session_name     = g_strdup (session_name);
+  gimp->no_data          = no_data          ? TRUE : FALSE;
+  gimp->no_fonts         = no_fonts         ? TRUE : FALSE;
+  gimp->no_interface     = no_interface     ? TRUE : FALSE;
+  gimp->use_shm          = use_shm          ? TRUE : FALSE;
+  gimp->use_cpu_accel    = use_cpu_accel    ? TRUE : FALSE;
+  gimp->console_messages = console_messages ? TRUE : FALSE;
+  gimp->show_playground  = show_playground  ? TRUE : FALSE;
+  gimp->show_debug_menu  = show_debug_menu  ? TRUE : FALSE;
+  gimp->stack_trace_mode = stack_trace_mode;
+  gimp->pdb_compat_mode  = pdb_compat_mode;
+
+  return gimp;
+}
+
+/**
+ * gimp_set_show_gui:
+ * @gimp:
+ * @show:
+ *
+ * Test cases that tests the UI typically don't want any windows to be
+ * presented during the test run. Allow them to set this.
+ **/
+void
+gimp_set_show_gui (Gimp     *gimp,
+                   gboolean  show_gui)
+{
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+
+  gimp->show_gui = show_gui;
+}
+
+/**
+ * gimp_get_show_gui:
+ * @gimp:
+ *
+ * Returns: %TRUE if the GUI should be shown, %FALSE otherwise.
+ **/
+gboolean
+gimp_get_show_gui (Gimp *gimp)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), FALSE);
+
+  return gimp->show_gui;
+}
+
+static void
+gimp_global_config_notify (GObject    *global_config,
+                           GParamSpec *param_spec,
+                           GObject    *edit_config)
+{
+  GValue global_value = G_VALUE_INIT;
+  GValue edit_value   = G_VALUE_INIT;
+
+  g_value_init (&global_value, param_spec->value_type);
+  g_value_init (&edit_value,   param_spec->value_type);
+
+  g_object_get_property (global_config, param_spec->name, &global_value);
+  g_object_get_property (edit_config,   param_spec->name, &edit_value);
+
+  if (g_param_values_cmp (param_spec, &global_value, &edit_value))
+    {
+      g_signal_handlers_block_by_func (edit_config,
+                                       gimp_edit_config_notify,
+                                       global_config);
+
+      g_object_set_property (edit_config, param_spec->name, &global_value);
+
+      g_signal_handlers_unblock_by_func (edit_config,
+                                         gimp_edit_config_notify,
+                                         global_config);
+    }
+
+  g_value_unset (&global_value);
+  g_value_unset (&edit_value);
+}
+
+static void
+gimp_edit_config_notify (GObject    *edit_config,
+                         GParamSpec *param_spec,
+                         GObject    *global_config)
+{
+  GValue edit_value   = G_VALUE_INIT;
+  GValue global_value = G_VALUE_INIT;
+
+  g_value_init (&edit_value,   param_spec->value_type);
+  g_value_init (&global_value, param_spec->value_type);
+
+  g_object_get_property (edit_config,   param_spec->name, &edit_value);
+  g_object_get_property (global_config, param_spec->name, &global_value);
+
+  if (g_param_values_cmp (param_spec, &edit_value, &global_value))
+    {
+      if (param_spec->flags & GIMP_CONFIG_PARAM_RESTART)
+        {
+#ifdef GIMP_CONFIG_DEBUG
+          g_print ("NOT Applying edit_config change of '%s' to global_config "
+                   "because it needs restart\n",
+                   param_spec->name);
+#endif
+        }
+      else
+        {
+#ifdef GIMP_CONFIG_DEBUG
+          g_print ("Applying edit_config change of '%s' to global_config\n",
+                   param_spec->name);
+#endif
+          g_signal_handlers_block_by_func (global_config,
+                                           gimp_global_config_notify,
+                                           edit_config);
+
+          g_object_set_property (global_config, param_spec->name, &edit_value);
+
+          g_signal_handlers_unblock_by_func (global_config,
+                                             gimp_global_config_notify,
+                                             edit_config);
+        }
+    }
+
+  g_value_unset (&edit_value);
+  g_value_unset (&global_value);
+}
+
+void
+gimp_load_config (Gimp  *gimp,
+                  GFile *alternate_system_gimprc,
+                  GFile *alternate_gimprc)
+{
+  GimpRc *gimprc;
+
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+  g_return_if_fail (alternate_system_gimprc == NULL ||
+                    G_IS_FILE (alternate_system_gimprc));
+  g_return_if_fail (alternate_gimprc == NULL ||
+                    G_IS_FILE (alternate_gimprc));
+  g_return_if_fail (gimp->config == NULL);
+  g_return_if_fail (gimp->edit_config == NULL);
+
+  if (gimp->be_verbose)
+    g_print ("INIT: %s\n", G_STRFUNC);
+
+  /*  this needs to be done before gimprc loading because gimprc can
+   *  use user defined units
+   */
+  gimp_unitrc_load (gimp);
+
+  gimprc = gimp_rc_new (G_OBJECT (gimp),
+                        alternate_system_gimprc,
+                        alternate_gimprc,
+                        gimp->be_verbose);
+
+  gimp->config = GIMP_CORE_CONFIG (gimprc);
+
+  gimp->edit_config = gimp_config_duplicate (GIMP_CONFIG (gimp->config));
+
+  g_signal_connect_object (gimp->config, "notify",
+                           G_CALLBACK (gimp_global_config_notify),
+                           gimp->edit_config, 0);
+  g_signal_connect_object (gimp->edit_config, "notify",
+                           G_CALLBACK (gimp_edit_config_notify),
+                           gimp->config, 0);
+
+  if (! gimp->show_playground)
+    {
+      gboolean    use_opencl;
+      gboolean    use_npd_tool;
+      gboolean    use_seamless_clone_tool;
+
+      /* Playground preferences is shown by default for unstable
+       * versions and if the associated CLI option was set. Additionally
+       * we want to show it if any of the playground options had been
+       * enabled. Otherwise you might end up getting blocked with a
+       * playground feature and forget where you can even disable it.
+       *
+       * Also we check this once at start when loading config, and not
+       * inside preferences-dialog.c because we don't want to end up
+       * with inconsistent behavior where you open once the Preferences,
+       * deactivate features, then back to preferences and the tab is
+       * gone.
+       */
+
+      g_object_get (gimp->edit_config,
+                    "use-opencl",                     &use_opencl,
+                    "playground-npd-tool",            &use_npd_tool,
+                    "playground-seamless-clone-tool", &use_seamless_clone_tool,
+                    NULL);
+      if (use_opencl || use_npd_tool || use_seamless_clone_tool)
+        gimp->show_playground = TRUE;
+    }
+}
+
+void
+gimp_initialize (Gimp               *gimp,
+                 GimpInitStatusFunc  status_callback)
+{
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+  g_return_if_fail (status_callback != NULL);
+  g_return_if_fail (GIMP_IS_CORE_CONFIG (gimp->config));
+
+  if (gimp->be_verbose)
+    g_print ("INIT: %s\n", G_STRFUNC);
+
+  g_signal_emit (gimp, gimp_signals[INITIALIZE], 0, status_callback);
+}
+
+/**
+ * gimp_restore:
+ * @gimp: a #Gimp object
+ * @error: a #GError for uncessful loading.
+ *
+ * This function always succeeds. If present, @error may be filled for
+ * possible feedback on data which failed to load. It doesn't imply any
+ * fatale error.
+ **/
+void
+gimp_restore (Gimp                *gimp,
+              GimpInitStatusFunc   status_callback,
+              GError             **error)
+{
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+  g_return_if_fail (status_callback != NULL);
+
+  if (gimp->be_verbose)
+    g_print ("INIT: %s\n", G_STRFUNC);
+
+  /*  initialize  the global parasite table  */
+  status_callback (_("Looking for data files"), _("Parasites"), 0.0);
+  gimp_parasiterc_load (gimp);
+
+  /*  initialize the lists of gimp brushes, dynamics, patterns etc.  */
+  gimp_data_factories_load (gimp, status_callback);
+
+  /*  initialize the template list  */
+  status_callback (NULL, _("Templates"), 0.8);
+  gimp_templates_load (gimp);
+
+  /*  initialize the module list  */
+  status_callback (NULL, _("Modules"), 0.9);
+  gimp_modules_load (gimp);
+
+  g_signal_emit (gimp, gimp_signals[RESTORE], 0, status_callback);
+
+  /* when done, make sure everything is clean, to clean out dirty
+   * states from data objects which reference each other and got
+   * dirtied by loading the referenced object
+   */
+  gimp_data_factories_data_clean (gimp);
+}
+
+/**
+ * gimp_is_restored:
+ * @gimp: a #Gimp object
+ *
+ * Return value: %TRUE if GIMP is completely started, %FALSE otherwise.
+ **/
+gboolean
+gimp_is_restored (Gimp *gimp)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), FALSE);
+
+  return gimp->restored;
+}
+
+/**
+ * gimp_exit:
+ * @gimp: a #Gimp object
+ * @force: whether to force the application to quit
+ *
+ * Exit this GIMP session. Unless @force is %TRUE, the user is queried
+ * whether unsaved images should be saved and can cancel the operation.
+ **/
+void
+gimp_exit (Gimp     *gimp,
+           gboolean  force)
+{
+  gboolean  handled;
+  GList    *image_iter;
+
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+
+  if (gimp->be_verbose)
+    g_print ("EXIT: %s\n", G_STRFUNC);
+
+  g_signal_emit (gimp, gimp_signals[EXIT], 0,
+                 force ? TRUE : FALSE,
+                 &handled);
+
+  if (handled)
+    return;
+
+  /* Get rid of images without display. We do this *after* handling the
+   * usual exit callbacks, because the things that are torn down there
+   * might have references to these images (for instance GimpActions
+   * in the UI manager).
+   */
+  while ((image_iter = gimp_get_image_iter (gimp)))
+    {
+      GimpImage *image = image_iter->data;
+
+      g_object_unref (image);
+    }
+}
+
+GList *
+gimp_get_image_iter (Gimp *gimp)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  return GIMP_LIST (gimp->images)->queue->head;
+}
+
+GList *
+gimp_get_display_iter (Gimp *gimp)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  return GIMP_LIST (gimp->displays)->queue->head;
+}
+
+GList *
+gimp_get_image_windows (Gimp *gimp)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  return g_list_copy (gimp->image_windows);
+}
+
+GList *
+gimp_get_paint_info_iter (Gimp *gimp)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  return GIMP_LIST (gimp->paint_info_list)->queue->head;
+}
+
+GList *
+gimp_get_tool_info_iter (Gimp *gimp)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  return GIMP_LIST (gimp->tool_info_list)->queue->head;
+}
+
+GList *
+gimp_get_tool_item_iter (Gimp *gimp)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  return GIMP_LIST (gimp->tool_item_list)->queue->head;
+}
+
+GList *
+gimp_get_tool_item_ui_iter (Gimp *gimp)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  return GIMP_LIST (gimp->tool_item_ui_list)->queue->head;
+}
+
+GimpObject *
+gimp_get_clipboard_object (Gimp *gimp)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  if (gimp->clipboard_image)
+    return GIMP_OBJECT (gimp->clipboard_image);
+
+  return GIMP_OBJECT (gimp->clipboard_buffer);
+}
+
+void
+gimp_set_clipboard_image (Gimp      *gimp,
+                          GimpImage *image)
+{
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+  g_return_if_fail (image == NULL || GIMP_IS_IMAGE (image));
+
+  g_clear_object (&gimp->clipboard_buffer);
+  g_set_object (&gimp->clipboard_image, image);
+
+  /* we want the signal emission */
+  g_signal_emit (gimp, gimp_signals[CLIPBOARD_CHANGED], 0);
+}
+
+GimpImage *
+gimp_get_clipboard_image (Gimp *gimp)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  return gimp->clipboard_image;
+}
+
+void
+gimp_set_clipboard_buffer (Gimp       *gimp,
+                           GimpBuffer *buffer)
+{
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+  g_return_if_fail (buffer == NULL || GIMP_IS_BUFFER (buffer));
+
+  g_clear_object (&gimp->clipboard_image);
+  g_set_object (&gimp->clipboard_buffer, buffer);
+
+  /* we want the signal emission */
+  g_signal_emit (gimp, gimp_signals[CLIPBOARD_CHANGED], 0);
+}
+
+GimpBuffer *
+gimp_get_clipboard_buffer (Gimp *gimp)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  return gimp->clipboard_buffer;
+}
+
+GimpImage *
+gimp_create_image (Gimp              *gimp,
+                   gint               width,
+                   gint               height,
+                   GimpImageBaseType  type,
+                   GimpPrecision      precision,
+                   gboolean           attach_comment)
+{
+  GimpImage *image;
+
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  image = gimp_image_new (gimp, width, height, type, precision);
+
+  if (attach_comment)
+    {
+      const gchar *comment;
+
+      comment = gimp_template_get_comment (gimp->config->default_image);
+
+      if (comment)
+        {
+          GimpParasite *parasite = gimp_parasite_new ("gimp-comment",
+                                                      GIMP_PARASITE_PERSISTENT,
+                                                      strlen (comment) + 1,
+                                                      comment);
+          gimp_image_parasite_attach (image, parasite, FALSE);
+          gimp_parasite_free (parasite);
+        }
+    }
+
+  return image;
+}
+
+void
+gimp_set_default_context (Gimp        *gimp,
+                          GimpContext *context)
+{
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+  g_return_if_fail (context == NULL || GIMP_IS_CONTEXT (context));
+
+  g_set_object (&gimp->default_context, context);
+}
+
+GimpContext *
+gimp_get_default_context (Gimp *gimp)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  return gimp->default_context;
+}
+
+void
+gimp_set_user_context (Gimp        *gimp,
+                       GimpContext *context)
+{
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+  g_return_if_fail (context == NULL || GIMP_IS_CONTEXT (context));
+
+  g_set_object (&gimp->user_context, context);
+}
+
+GimpContext *
+gimp_get_user_context (Gimp *gimp)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  return gimp->user_context;
+}
+
+GimpToolInfo *
+gimp_get_tool_info (Gimp        *gimp,
+                    const gchar *tool_id)
+{
+  gpointer info;
+
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+  g_return_val_if_fail (tool_id != NULL, NULL);
+
+  info = gimp_container_get_child_by_name (gimp->tool_info_list, tool_id);
+
+  return (GimpToolInfo *) info;
+}
+
+/**
+ * gimp_message:
+ * @gimp:     a pointer to the %Gimp object
+ * @handler:  either a %GimpProgress or a %GtkWidget pointer
+ * @severity: severity of the message
+ * @format:   printf-like format string
+ * @...:      arguments to use with @format
+ *
+ * Present a message to the user. How exactly the message is displayed
+ * depends on the @severity, the @handler object and user preferences.
+ **/
+void
+gimp_message (Gimp                *gimp,
+              GObject             *handler,
+              GimpMessageSeverity  severity,
+              const gchar         *format,
+              ...)
+{
+  va_list args;
+
+  va_start (args, format);
+
+  gimp_message_valist (gimp, handler, severity, format, args);
+
+  va_end (args);
+}
+
+/**
+ * gimp_message_valist:
+ * @gimp:     a pointer to the %Gimp object
+ * @handler:  either a %GimpProgress or a %GtkWidget pointer
+ * @severity: severity of the message
+ * @format:   printf-like format string
+ * @args:     arguments to use with @format
+ *
+ * See documentation for gimp_message().
+ **/
+void
+gimp_message_valist (Gimp                *gimp,
+                     GObject             *handler,
+                     GimpMessageSeverity  severity,
+                     const gchar         *format,
+                     va_list              args)
+{
+  gchar *message;
+
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+  g_return_if_fail (handler == NULL || G_IS_OBJECT (handler));
+  g_return_if_fail (format != NULL);
+
+  message = g_strdup_vprintf (format, args);
+
+  gimp_show_message (gimp, handler, severity, NULL, message);
+
+  g_free (message);
+}
+
+void
+gimp_message_literal (Gimp                *gimp,
+                      GObject             *handler,
+                      GimpMessageSeverity  severity,
+                      const gchar         *message)
+{
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+  g_return_if_fail (handler == NULL || G_IS_OBJECT (handler));
+  g_return_if_fail (message != NULL);
+
+  gimp_show_message (gimp, handler, severity, NULL, message);
+}
+
+void
+gimp_filter_history_changed (Gimp *gimp)
+{
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+
+  g_signal_emit (gimp, gimp_signals[FILTER_HISTORY_CHANGED], 0);
+}
+
+void
+gimp_image_opened (Gimp  *gimp,
+                   GFile *file)
+{
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+  g_return_if_fail (G_IS_FILE (file));
+
+  g_signal_emit (gimp, gimp_signals[IMAGE_OPENED], 0, file);
+}
+
+GFile *
+gimp_get_temp_file (Gimp        *gimp,
+                    const gchar *extension)
+{
+  static gint  id = 0;
+  static gint  pid;
+  gchar       *basename;
+  GFile       *dir;
+  GFile       *file;
+
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  if (id == 0)
+    pid = gimp_get_pid ();
+
+  if (extension)
+    basename = g_strdup_printf ("gimp-temp-%d%d.%s", pid, id++, extension);
+  else
+    basename = g_strdup_printf ("gimp-temp-%d%d", pid, id++);
+
+  dir = gimp_file_new_for_config_path (GIMP_GEGL_CONFIG (gimp->config)->temp_path,
+                                       NULL);
+  if (! g_file_query_exists (dir, NULL))
+    {
+      /* Try to make the temp directory if it doesn't exist.
+       * Ignore any error.
+       */
+      g_file_make_directory_with_parents (dir, NULL, NULL);
+    }
+  file = g_file_get_child (dir, basename);
+  g_free (basename);
+  g_object_unref (dir);
+
+  return file;
+}
diff --git a/app/core/gimp.h b/app/core/gimp.h
new file mode 100644
index 0000000..d4b1e39
--- /dev/null
+++ b/app/core/gimp.h
@@ -0,0 +1,248 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1997 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_H__
+#define __GIMP_H__
+
+
+#include "gimpobject.h"
+#include "gimp-gui.h"
+
+
+#define GIMP_TYPE_GIMP            (gimp_get_type ())
+#define GIMP(obj)                 (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_GIMP, Gimp))
+#define GIMP_CLASS(klass)         (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_GIMP, GimpClass))
+#define GIMP_IS_GIMP(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_GIMP))
+#define GIMP_IS_GIMP_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_GIMP))
+
+
+typedef struct _GimpClass GimpClass;
+
+struct _Gimp
+{
+  GimpObject              parent_instance;
+
+  GimpCoreConfig         *config;
+  GimpCoreConfig         *edit_config; /* don't use this one, it's just
+                                        * for the preferences dialog
+                                        */
+  gchar                  *session_name;
+  GFile                  *default_folder;
+
+  gboolean                be_verbose;
+  gboolean                no_data;
+  gboolean                no_fonts;
+  gboolean                no_interface;
+  gboolean                show_gui;
+  gboolean                use_shm;
+  gboolean                use_cpu_accel;
+  GimpMessageHandlerType  message_handler;
+  gboolean                console_messages;
+  gboolean                show_playground;
+  gboolean                show_debug_menu;
+  GimpStackTraceMode      stack_trace_mode;
+  GimpPDBCompatMode       pdb_compat_mode;
+
+  GimpGui                 gui;         /* gui vtable */
+
+  gboolean                restored;    /* becomes TRUE in gimp_restore() */
+  gboolean                initialized; /* Fully initialized (only set once at start). */
+
+  gint                    busy;
+  guint                   busy_idle_id;
+
+  GList                  *user_units;
+  gint                    n_user_units;
+
+  GimpParasiteList       *parasites;
+
+  GimpContainer          *paint_info_list;
+  GimpPaintInfo          *standard_paint_info;
+
+  GimpModuleDB           *module_db;
+  gboolean                write_modulerc;
+
+  GimpPlugInManager      *plug_in_manager;
+
+  GList                  *filter_history;
+
+  GimpContainer          *images;
+  guint32                 next_guide_ID;
+  guint32                 next_sample_point_ID;
+  GimpIdTable            *image_table;
+  GimpIdTable            *item_table;
+
+  GimpContainer          *displays;
+  gint                    next_display_ID;
+
+  GList                  *image_windows;
+
+  GimpImage              *clipboard_image;
+  GimpBuffer             *clipboard_buffer;
+  GimpContainer          *named_buffers;
+
+  GimpDataFactory        *brush_factory;
+  GimpDataFactory        *dynamics_factory;
+  GimpDataFactory        *mybrush_factory;
+  GimpDataFactory        *pattern_factory;
+  GimpDataFactory        *gradient_factory;
+  GimpDataFactory        *palette_factory;
+  GimpDataFactory        *font_factory;
+  GimpDataFactory        *tool_preset_factory;
+
+  GimpTagCache           *tag_cache;
+
+  GimpPDB                *pdb;
+
+  GimpContainer          *tool_info_list;
+  GimpToolInfo           *standard_tool_info;
+
+  GimpContainer          *tool_item_list;
+  GimpContainer          *tool_item_ui_list;
+
+  /*  the opened and saved images in MRU order  */
+  GimpContainer          *documents;
+
+  /*  image_new values  */
+  GimpContainer          *templates;
+  GimpTemplate           *image_new_last_template;
+
+  /*  the list of all contexts  */
+  GList                  *context_list;
+
+  /*  the default context which is initialized from gimprc  */
+  GimpContext            *default_context;
+
+  /*  the context used by the interface  */
+  GimpContext            *user_context;
+};
+
+struct _GimpClass
+{
+  GimpObjectClass  parent_class;
+
+  void     (* initialize)             (Gimp               *gimp,
+                                       GimpInitStatusFunc  status_callback);
+  void     (* restore)                (Gimp               *gimp,
+                                       GimpInitStatusFunc  status_callback);
+  gboolean (* exit)                   (Gimp               *gimp,
+                                       gboolean            force);
+
+  void     (* clipboard_changed)      (Gimp               *gimp);
+
+  void     (* filter_history_changed) (Gimp               *gimp);
+
+  /*  emitted if an image is loaded and opened with a display  */
+  void     (* image_opened)           (Gimp               *gimp,
+                                       GFile              *file);
+};
+
+
+GType          gimp_get_type               (void) G_GNUC_CONST;
+
+Gimp         * gimp_new                    (const gchar         *name,
+                                            const gchar         *session_name,
+                                            GFile               *default_folder,
+                                            gboolean             be_verbose,
+                                            gboolean             no_data,
+                                            gboolean             no_fonts,
+                                            gboolean             no_interface,
+                                            gboolean             use_shm,
+                                            gboolean             use_cpu_accel,
+                                            gboolean             console_messages,
+                                            gboolean             show_playground,
+                                            gboolean             show_debug_menu,
+                                            GimpStackTraceMode   stack_trace_mode,
+                                            GimpPDBCompatMode    pdb_compat_mode);
+void           gimp_set_show_gui           (Gimp                *gimp,
+                                            gboolean             show_gui);
+gboolean       gimp_get_show_gui           (Gimp                *gimp);
+
+void           gimp_load_config            (Gimp                *gimp,
+                                            GFile               *alternate_system_gimprc,
+                                            GFile               *alternate_gimprc);
+void           gimp_initialize             (Gimp                *gimp,
+                                            GimpInitStatusFunc   status_callback);
+void           gimp_restore                (Gimp                *gimp,
+                                            GimpInitStatusFunc   status_callback,
+                                            GError             **error);
+gboolean       gimp_is_restored            (Gimp                *gimp);
+
+void           gimp_exit                   (Gimp                *gimp,
+                                            gboolean             force);
+
+GList        * gimp_get_image_iter         (Gimp                *gimp);
+GList        * gimp_get_display_iter       (Gimp                *gimp);
+GList        * gimp_get_image_windows      (Gimp                *gimp);
+GList        * gimp_get_paint_info_iter    (Gimp                *gimp);
+GList        * gimp_get_tool_info_iter     (Gimp                *gimp);
+GList        * gimp_get_tool_item_iter     (Gimp                *gimp);
+GList        * gimp_get_tool_item_ui_iter  (Gimp                *gimp);
+
+GimpObject   * gimp_get_clipboard_object   (Gimp                *gimp);
+
+void           gimp_set_clipboard_image    (Gimp                *gimp,
+                                            GimpImage           *image);
+GimpImage    * gimp_get_clipboard_image    (Gimp                *gimp);
+
+void           gimp_set_clipboard_buffer   (Gimp                *gimp,
+                                            GimpBuffer          *buffer);
+GimpBuffer   * gimp_get_clipboard_buffer   (Gimp                *gimp);
+
+GimpImage    * gimp_create_image           (Gimp                *gimp,
+                                            gint                 width,
+                                            gint                 height,
+                                            GimpImageBaseType    type,
+                                            GimpPrecision        precision,
+                                            gboolean             attach_comment);
+
+void           gimp_set_default_context    (Gimp                *gimp,
+                                            GimpContext         *context);
+GimpContext  * gimp_get_default_context    (Gimp                *gimp);
+
+void           gimp_set_user_context       (Gimp                *gimp,
+                                            GimpContext         *context);
+GimpContext  * gimp_get_user_context       (Gimp                *gimp);
+
+GimpToolInfo * gimp_get_tool_info          (Gimp                *gimp,
+                                            const gchar         *tool_name);
+
+void           gimp_message                (Gimp                *gimp,
+                                            GObject             *handler,
+                                            GimpMessageSeverity  severity,
+                                            const gchar         *format,
+                                            ...) G_GNUC_PRINTF (4, 5);
+void           gimp_message_valist         (Gimp                *gimp,
+                                            GObject             *handler,
+                                            GimpMessageSeverity  severity,
+                                            const gchar         *format,
+                                            va_list              args) G_GNUC_PRINTF (4, 0);
+void           gimp_message_literal        (Gimp                *gimp,
+                                            GObject             *handler,
+                                            GimpMessageSeverity  severity,
+                                            const gchar         *message);
+
+void           gimp_filter_history_changed (Gimp                *gimp);
+
+void           gimp_image_opened           (Gimp                *gimp,
+                                            GFile               *file);
+
+GFile        * gimp_get_temp_file          (Gimp                *gimp,
+                                            const gchar         *extension);
+
+
+#endif  /* __GIMP_H__ */
diff --git a/app/core/gimpasync.c b/app/core/gimpasync.c
new file mode 100644
index 0000000..322d57d
--- /dev/null
+++ b/app/core/gimpasync.c
@@ -0,0 +1,752 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpasync.c
+ * Copyright (C) 2018 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gimpasync.h"
+#include "gimpcancelable.h"
+#include "gimpmarshal.h"
+#include "gimpwaitable.h"
+
+
+/* GimpAsync represents an asynchronous task.  Both the public and the
+ * protected interfaces are intentionally minimal at this point, to keep things
+ * simple.  They may be extended in the future as needed.
+ *
+ * GimpAsync implements the GimpWaitable and GimpCancelable interfaces.
+ *
+ * Upon creation, a GimpAsync object is in the "running" state.  Once the task
+ * is complete (and before the object's destruction), it should be transitioned
+ * to the "stopped" state, using either 'gimp_async_finish()' or
+ * 'gimp_async_abort()'.
+ *
+ * Similarly, upon creation, a GimpAsync object is said to be "unsynced".  It
+ * becomes synced once the execution of any of the completion callbacks added
+ * through 'gimp_async_add_callback()' had started, or after a successful call
+ * to one of the 'gimp_waitable_wait()' family of functions.
+ *
+ * Note that certain GimpAsync functions may only be called during a certain
+ * state, on a certain thread, or depending on whether or not the object is
+ * synced, as detailed for each function.  When referring to threads, the "main
+ * thread" is the thread running the main loop, or any thread whose execution
+ * is synchronized with the main thread, and the "async thread" is the thread
+ * calling 'gimp_async_finish()' or 'gimp_async_abort()' (which may also be the
+ * main thread), or any thread whose execution is synchronized with the async
+ * thread.
+ */
+
+
+/* #define TIME_ASYNC_OPS */
+
+
+enum
+{
+  WAITING,
+  LAST_SIGNAL
+};
+
+
+typedef struct _GimpAsyncCallbackInfo GimpAsyncCallbackInfo;
+
+
+struct _GimpAsyncCallbackInfo
+{
+  GimpAsync         *async;
+  GimpAsyncCallback  callback;
+  gpointer           data;
+  gpointer           gobject;
+};
+
+struct _GimpAsyncPrivate
+{
+  GMutex         mutex;
+  GCond          cond;
+
+  GQueue         callbacks;
+
+  gpointer       result;
+  GDestroyNotify result_destroy_func;
+
+  guint          idle_id;
+
+  gboolean       stopped;
+  gboolean       finished;
+  gboolean       synced;
+  gboolean       canceled;
+
+#ifdef TIME_ASYNC_OPS
+  guint64        start_time;
+#endif
+};
+
+
+/*  local function prototypes  */
+
+static void       gimp_async_waitable_iface_init   (GimpWaitableInterface   *iface);
+
+static void       gimp_async_cancelable_iface_init (GimpCancelableInterface *iface);
+
+static void       gimp_async_finalize              (GObject                 *object);
+
+static void       gimp_async_wait                  (GimpWaitable            *waitable);
+static gboolean   gimp_async_try_wait              (GimpWaitable            *waitable);
+static gboolean   gimp_async_wait_until            (GimpWaitable            *waitable,
+                                                    gint64                   end_time);
+
+static void       gimp_async_cancel                (GimpCancelable          *cancelable);
+
+static gboolean   gimp_async_idle                  (GimpAsync               *async);
+
+static void       gimp_async_callback_weak_notify  (GimpAsyncCallbackInfo   *callback_info,
+                                                    GObject                 *gobject);
+
+static void       gimp_async_stop                  (GimpAsync               *async);
+static void       gimp_async_run_callbacks         (GimpAsync               *async);
+
+
+G_DEFINE_TYPE_WITH_CODE (GimpAsync, gimp_async, G_TYPE_OBJECT,
+                         G_ADD_PRIVATE (GimpAsync)
+                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_WAITABLE,
+                                                gimp_async_waitable_iface_init)
+                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_CANCELABLE,
+                                                gimp_async_cancelable_iface_init))
+
+#define parent_class gimp_async_parent_class
+
+static guint async_signals[LAST_SIGNAL] = { 0 };
+
+
+/*  local variables  */
+
+static volatile gint gimp_async_n_running = 0;
+
+
+/*  private functions  */
+
+
+static void
+gimp_async_class_init (GimpAsyncClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  async_signals[WAITING] =
+    g_signal_new ("waiting",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpAsyncClass, waiting),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  object_class->finalize = gimp_async_finalize;
+}
+
+static void
+gimp_async_waitable_iface_init (GimpWaitableInterface *iface)
+{
+  iface->wait       = gimp_async_wait;
+  iface->try_wait   = gimp_async_try_wait;
+  iface->wait_until = gimp_async_wait_until;
+}
+
+static void
+gimp_async_cancelable_iface_init (GimpCancelableInterface *iface)
+{
+  iface->cancel = gimp_async_cancel;
+}
+
+static void
+gimp_async_init (GimpAsync *async)
+{
+  async->priv = gimp_async_get_instance_private (async);
+
+  g_mutex_init (&async->priv->mutex);
+  g_cond_init  (&async->priv->cond);
+
+  g_queue_init (&async->priv->callbacks);
+
+  g_atomic_int_inc (&gimp_async_n_running);
+
+#ifdef TIME_ASYNC_OPS
+  async->priv->start_time = g_get_monotonic_time ();
+#endif
+}
+
+static void
+gimp_async_finalize (GObject *object)
+{
+  GimpAsync *async = GIMP_ASYNC (object);
+
+  g_warn_if_fail (async->priv->stopped);
+  g_warn_if_fail (async->priv->idle_id == 0);
+  g_warn_if_fail (g_queue_is_empty (&async->priv->callbacks));
+
+  if (async->priv->finished &&
+      async->priv->result   &&
+      async->priv->result_destroy_func)
+    {
+      async->priv->result_destroy_func (async->priv->result);
+
+      async->priv->result = NULL;
+    }
+
+  g_cond_clear  (&async->priv->cond);
+  g_mutex_clear (&async->priv->mutex);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+/* waits for 'waitable' to transition to the "stopped" state.  if 'waitable' is
+ * already stopped, returns immediately.
+ *
+ * after the call, all callbacks previously added through
+ * 'gimp_async_add_callback()' are guaranteed to have been called.
+ *
+ * may only be called on the main thread.
+ */
+static void
+gimp_async_wait (GimpWaitable *waitable)
+{
+  GimpAsync *async = GIMP_ASYNC (waitable);
+
+  g_mutex_lock (&async->priv->mutex);
+
+  if (! async->priv->stopped)
+    {
+      g_signal_emit (async, async_signals[WAITING], 0);
+
+      while (! async->priv->stopped)
+        g_cond_wait (&async->priv->cond, &async->priv->mutex);
+    }
+
+  g_mutex_unlock (&async->priv->mutex);
+
+  gimp_async_run_callbacks (async);
+}
+
+/* same as 'gimp_async_wait()', but returns immediately if 'waitable' is not in
+ * the "stopped" state.
+ *
+ * returns TRUE if 'waitable' has transitioned to the "stopped" state, or FALSE
+ * otherwise.
+ */
+static gboolean
+gimp_async_try_wait (GimpWaitable *waitable)
+{
+  GimpAsync *async = GIMP_ASYNC (waitable);
+
+  g_mutex_lock (&async->priv->mutex);
+
+  if (! async->priv->stopped)
+    {
+      g_mutex_unlock (&async->priv->mutex);
+
+      return FALSE;
+    }
+
+  g_mutex_unlock (&async->priv->mutex);
+
+  gimp_async_run_callbacks (async);
+
+  return TRUE;
+}
+
+/* same as 'gimp_async_wait()', taking an additional 'end_time' parameter,
+ * specifying the maximal monotonic time until which to wait for 'waitable' to
+ * stop.
+ *
+ * returns TRUE if 'waitable' has transitioned to the "stopped" state, or FALSE
+ * if the wait was interrupted before the transition.
+ */
+static gboolean
+gimp_async_wait_until (GimpWaitable *waitable,
+                       gint64        end_time)
+{
+  GimpAsync *async = GIMP_ASYNC (waitable);
+
+  g_mutex_lock (&async->priv->mutex);
+
+  if (! async->priv->stopped)
+    {
+      g_signal_emit (async, async_signals[WAITING], 0);
+
+      while (! async->priv->stopped)
+        {
+          if (! g_cond_wait_until (&async->priv->cond, &async->priv->mutex,
+                                   end_time))
+            {
+              g_mutex_unlock (&async->priv->mutex);
+
+              return FALSE;
+            }
+        }
+    }
+
+  g_mutex_unlock (&async->priv->mutex);
+
+  gimp_async_run_callbacks (async);
+
+  return TRUE;
+}
+
+/* requests the cancellation of the task managed by 'cancelable'.
+ *
+ * note that 'gimp_async_cancel()' doesn't directly cause 'cancelable' to be
+ * stopped, nor synced.  furthermore, 'cancelable' may still complete
+ * successfully even when cancellation has been requested.
+ *
+ * may only be called on the main thread.
+ */
+static void
+gimp_async_cancel (GimpCancelable *cancelable)
+{
+  GimpAsync *async = GIMP_ASYNC (cancelable);
+
+  async->priv->canceled = TRUE;
+}
+
+static gboolean
+gimp_async_idle (GimpAsync *async)
+{
+  gimp_waitable_wait (GIMP_WAITABLE (async));
+
+  return G_SOURCE_REMOVE;
+}
+
+static void
+gimp_async_callback_weak_notify (GimpAsyncCallbackInfo *callback_info,
+                                 GObject               *gobject)
+{
+  GimpAsync *async       = callback_info->async;
+  gboolean   unref_async = FALSE;
+
+  g_mutex_lock (&async->priv->mutex);
+
+  g_queue_remove (&async->priv->callbacks, callback_info);
+
+  g_slice_free (GimpAsyncCallbackInfo, callback_info);
+
+  if (g_queue_is_empty (&async->priv->callbacks) && async->priv->idle_id)
+    {
+      g_source_remove (async->priv->idle_id);
+      async->priv->idle_id = 0;
+
+      unref_async = TRUE;
+    }
+
+  g_mutex_unlock (&async->priv->mutex);
+
+  if (unref_async)
+    g_object_unref (async);
+}
+
+static void
+gimp_async_stop (GimpAsync *async)
+{
+#ifdef TIME_ASYNC_OPS
+  {
+    guint64 time = g_get_monotonic_time ();
+
+    g_printerr ("Asynchronous operation took %g seconds%s\n",
+                (time - async->priv->start_time) / 1000000.0,
+                async->priv->finished ? "" : " (aborted)");
+  }
+#endif
+
+  g_atomic_int_dec_and_test (&gimp_async_n_running);
+
+  if (! g_queue_is_empty (&async->priv->callbacks))
+    {
+      g_object_ref (async);
+
+      async->priv->idle_id = g_idle_add_full (G_PRIORITY_DEFAULT,
+                                              (GSourceFunc) gimp_async_idle,
+                                              async, NULL);
+    }
+
+  async->priv->stopped = TRUE;
+
+  g_cond_broadcast (&async->priv->cond);
+}
+
+static void
+gimp_async_run_callbacks (GimpAsync *async)
+{
+  GimpAsyncCallbackInfo *callback_info;
+  gboolean               unref_async = FALSE;
+
+  if (async->priv->idle_id)
+    {
+      g_source_remove (async->priv->idle_id);
+      async->priv->idle_id = 0;
+
+      unref_async = TRUE;
+    }
+
+  async->priv->synced = TRUE;
+
+  while ((callback_info = g_queue_pop_head (&async->priv->callbacks)))
+    {
+      if (callback_info->gobject)
+        {
+          g_object_ref (callback_info->gobject);
+
+          g_object_weak_unref (callback_info->gobject,
+                               (GWeakNotify) gimp_async_callback_weak_notify,
+                               callback_info);
+        }
+
+      callback_info->callback (async, callback_info->data);
+
+      if (callback_info->gobject)
+        g_object_unref (callback_info->gobject);
+
+      g_slice_free (GimpAsyncCallbackInfo, callback_info);
+    }
+
+  if (unref_async)
+    g_object_unref (async);
+}
+
+
+/*  public functions  */
+
+
+/* creates a new GimpAsync object, initially unsynced and placed in the
+ * "running" state.
+ */
+GimpAsync *
+gimp_async_new (void)
+{
+  return g_object_new (GIMP_TYPE_ASYNC,
+                       NULL);
+}
+
+/* checks if 'async' is synced.
+ *
+ * may only be called on the main thread.
+ */
+gboolean
+gimp_async_is_synced (GimpAsync *async)
+{
+  g_return_val_if_fail (GIMP_IS_ASYNC (async), FALSE);
+
+  return async->priv->synced;
+}
+
+/* registers a callback to be called when 'async' transitions to the "stopped"
+ * state.  if 'async' is already stopped, the callback may be called directly.
+ *
+ * callbacks are called in the order in which they were added.  'async' is
+ * guaranteed to be kept alive, even without an external reference, between the
+ * point where it was stopped, and until all callbacks added while 'async' was
+ * externally referenced have been called.
+ *
+ * the callback is guaranteed to be called on the main thread.
+ *
+ * may only be called on the main thread.
+ */
+void
+gimp_async_add_callback (GimpAsync         *async,
+                         GimpAsyncCallback  callback,
+                         gpointer           data)
+{
+  GimpAsyncCallbackInfo *callback_info;
+
+  g_return_if_fail (GIMP_IS_ASYNC (async));
+  g_return_if_fail (callback != NULL);
+
+  g_mutex_lock (&async->priv->mutex);
+
+  if (async->priv->stopped && g_queue_is_empty (&async->priv->callbacks))
+    {
+      async->priv->synced = TRUE;
+
+      g_mutex_unlock (&async->priv->mutex);
+
+      callback (async, data);
+
+      return;
+    }
+
+  callback_info           = g_slice_new0 (GimpAsyncCallbackInfo);
+  callback_info->async    = async;
+  callback_info->callback = callback;
+  callback_info->data     = data;
+
+  g_queue_push_tail (&async->priv->callbacks, callback_info);
+
+  g_mutex_unlock (&async->priv->mutex);
+}
+
+/* same as 'gimp_async_add_callback()', however, takes an additional 'gobject'
+ * argument, which should be a GObject.
+ *
+ * 'gobject' is guaranteed to remain alive for the duration of the callback.
+ *
+ * When 'gobject' is destroyed, the callback is automatically removed.
+ */
+void
+gimp_async_add_callback_for_object (GimpAsync         *async,
+                                    GimpAsyncCallback  callback,
+                                    gpointer           data,
+                                    gpointer           gobject)
+{
+  GimpAsyncCallbackInfo *callback_info;
+
+  g_return_if_fail (GIMP_IS_ASYNC (async));
+  g_return_if_fail (callback != NULL);
+  g_return_if_fail (G_IS_OBJECT (gobject));
+
+  g_mutex_lock (&async->priv->mutex);
+
+  if (async->priv->stopped && g_queue_is_empty (&async->priv->callbacks))
+    {
+      async->priv->synced = TRUE;
+
+      g_mutex_unlock (&async->priv->mutex);
+
+      g_object_ref (gobject);
+
+      callback (async, data);
+
+      g_object_unref (gobject);
+
+      return;
+    }
+
+  callback_info           = g_slice_new0 (GimpAsyncCallbackInfo);
+  callback_info->async    = async;
+  callback_info->callback = callback;
+  callback_info->data     = data;
+  callback_info->gobject  = gobject;
+
+  g_queue_push_tail (&async->priv->callbacks, callback_info);
+
+  g_object_weak_ref (gobject,
+                     (GWeakNotify) gimp_async_callback_weak_notify,
+                     callback_info);
+
+  g_mutex_unlock (&async->priv->mutex);
+}
+
+/* removes all callbacks previously registered through
+ * 'gimp_async_add_callback()', matching 'callback' and 'data', which hasn't
+ * been called yet.
+ *
+ * may only be called on the main thread.
+ */
+void
+gimp_async_remove_callback (GimpAsync         *async,
+                            GimpAsyncCallback  callback,
+                            gpointer           data)
+{
+  GList    *iter;
+  gboolean  unref_async = FALSE;
+
+  g_return_if_fail (GIMP_IS_ASYNC (async));
+  g_return_if_fail (callback != NULL);
+
+  g_mutex_lock (&async->priv->mutex);
+
+  iter = g_queue_peek_head_link (&async->priv->callbacks);
+
+  while (iter)
+    {
+      GimpAsyncCallbackInfo *callback_info = iter->data;
+      GList                 *next          = g_list_next (iter);
+
+      if (callback_info->callback == callback &&
+          callback_info->data     == data)
+        {
+          if (callback_info->gobject)
+            {
+              g_object_weak_unref (
+                callback_info->gobject,
+                (GWeakNotify) gimp_async_callback_weak_notify,
+                callback_info);
+            }
+
+          g_queue_delete_link (&async->priv->callbacks, iter);
+
+          g_slice_free (GimpAsyncCallbackInfo, callback_info);
+        }
+
+      iter = next;
+    }
+
+  if (g_queue_is_empty (&async->priv->callbacks) && async->priv->idle_id)
+    {
+      g_source_remove (async->priv->idle_id);
+      async->priv->idle_id = 0;
+
+      unref_async = TRUE;
+    }
+
+  g_mutex_unlock (&async->priv->mutex);
+
+  if (unref_async)
+    g_object_unref (async);
+}
+
+/* checks if 'async' is in the "stopped" state.
+ *
+ * may only be called on the async thread.
+ */
+gboolean
+gimp_async_is_stopped (GimpAsync *async)
+{
+  g_return_val_if_fail (GIMP_IS_ASYNC (async), FALSE);
+
+  return async->priv->stopped;
+}
+
+/* transitions 'async' to the "stopped" state, indicating that the task
+ * completed normally, possibly providing a result.
+ *
+ * 'async' shall be in the "running" state.
+ *
+ * may only be called on the async thread.
+ */
+void
+gimp_async_finish (GimpAsync *async,
+                   gpointer   result)
+{
+  gimp_async_finish_full (async, result, NULL);
+}
+
+/* same as 'gimp_async_finish()', taking an additional GDestroyNotify function,
+ * used for freeing the result when 'async' is destroyed.
+ */
+void
+gimp_async_finish_full (GimpAsync      *async,
+                        gpointer        result,
+                        GDestroyNotify  result_destroy_func)
+{
+  g_return_if_fail (GIMP_IS_ASYNC (async));
+  g_return_if_fail (! async->priv->stopped);
+
+  g_mutex_lock (&async->priv->mutex);
+
+  async->priv->finished            = TRUE;
+  async->priv->result              = result;
+  async->priv->result_destroy_func = result_destroy_func;
+
+  gimp_async_stop (async);
+
+  g_mutex_unlock (&async->priv->mutex);
+}
+
+/* checks if 'async' completed normally, using 'gimp_async_finish()' (in
+ * contrast to 'gimp_async_abort()').
+ *
+ * 'async' shall be in the "stopped" state.
+ *
+ * may only be called on the async thread, or on the main thread when 'async'
+ * is synced.
+ */
+gboolean
+gimp_async_is_finished (GimpAsync *async)
+{
+  g_return_val_if_fail (GIMP_IS_ASYNC (async), FALSE);
+  g_return_val_if_fail (async->priv->stopped, FALSE);
+
+  return async->priv->finished;
+}
+
+/* returns the result of 'async', as passed to 'gimp_async_finish()'.
+ *
+ * 'async' shall be in the "stopped" state, and should have completed normally.
+ *
+ * may only be called on the async thread, or on the main thread when 'async'
+ * is synced.
+ */
+gpointer
+gimp_async_get_result (GimpAsync *async)
+{
+  g_return_val_if_fail (GIMP_IS_ASYNC (async), NULL);
+  g_return_val_if_fail (async->priv->stopped, NULL);
+  g_return_val_if_fail (async->priv->finished, NULL);
+
+  return async->priv->result;
+}
+
+/* transitions 'async' to the "stopped" state, indicating that the task
+ * was stopped before completion (normally, in response to a
+ * 'gimp_cancelable_cancel()' call).
+ *
+ * 'async' shall be in the "running" state.
+ *
+ * may only be called on the async thread.
+ */
+void
+gimp_async_abort (GimpAsync *async)
+{
+  g_return_if_fail (GIMP_IS_ASYNC (async));
+  g_return_if_fail (! async->priv->stopped);
+
+  g_mutex_lock (&async->priv->mutex);
+
+  gimp_async_stop (async);
+
+  g_mutex_unlock (&async->priv->mutex);
+}
+
+/* checks if cancellation of 'async' has been requested.
+ *
+ * note that a return value of TRUE only indicates that
+ * 'gimp_cancelable_cancel()' has been called for 'async', and not that 'async'
+ * is stopped, or, if it is stopped, that it was aborted.
+ */
+gboolean
+gimp_async_is_canceled (GimpAsync *async)
+{
+  g_return_val_if_fail (GIMP_IS_ASYNC (async), FALSE);
+
+  return async->priv->canceled;
+}
+
+/* a convenience function, canceling 'async' and waiting for it to stop.
+ *
+ * may only be called on the main thread.
+ */
+void
+gimp_async_cancel_and_wait (GimpAsync *async)
+{
+  g_return_if_fail (GIMP_IS_ASYNC (async));
+
+  gimp_cancelable_cancel (GIMP_CANCELABLE (async));
+  gimp_waitable_wait (GIMP_WAITABLE (async));
+}
+
+
+/*  public functions (stats)  */
+
+
+gint
+gimp_async_get_n_running (void)
+{
+  return gimp_async_n_running;
+}
diff --git a/app/core/gimpasync.h b/app/core/gimpasync.h
new file mode 100644
index 0000000..0c2a671
--- /dev/null
+++ b/app/core/gimpasync.h
@@ -0,0 +1,95 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpasync.h
+ * Copyright (C) 2018 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_ASYNC_H__
+#define __GIMP_ASYNC_H__
+
+
+#define GIMP_TYPE_ASYNC            (gimp_async_get_type ())
+#define GIMP_ASYNC(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_ASYNC, GimpAsync))
+#define GIMP_ASYNC_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_ASYNC, GimpAsyncClass))
+#define GIMP_IS_ASYNC(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_ASYNC))
+#define GIMP_IS_ASYNC_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_ASYNC))
+#define GIMP_ASYNC_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_ASYNC, GimpAsyncClass))
+
+
+typedef void (* GimpAsyncCallback) (GimpAsync *async,
+                                    gpointer   data);
+
+
+typedef struct _GimpAsyncPrivate GimpAsyncPrivate;
+typedef struct _GimpAsyncClass   GimpAsyncClass;
+
+struct _GimpAsync
+{
+  GObject           parent_instance;
+
+  GimpAsyncPrivate *priv;
+};
+
+struct _GimpAsyncClass
+{
+  GObjectClass  parent_class;
+
+  /*  signals  */
+  void   (* waiting) (GimpAsync *async);
+};
+
+
+GType       gimp_async_get_type                (void) G_GNUC_CONST;
+
+GimpAsync * gimp_async_new                     (void);
+
+gboolean    gimp_async_is_synced               (GimpAsync         *async);
+
+void        gimp_async_add_callback            (GimpAsync         *async,
+                                                GimpAsyncCallback  callback,
+                                                gpointer           data);
+void        gimp_async_add_callback_for_object (GimpAsync         *async,
+                                                GimpAsyncCallback  callback,
+                                                gpointer           data,
+                                                gpointer           gobject);
+void        gimp_async_remove_callback         (GimpAsync         *async,
+                                                GimpAsyncCallback  callback,
+                                                gpointer           data);
+
+gboolean    gimp_async_is_stopped              (GimpAsync         *async);
+
+void        gimp_async_finish                  (GimpAsync         *async,
+                                                gpointer           result);
+void        gimp_async_finish_full             (GimpAsync         *async,
+                                                gpointer           result,
+                                                GDestroyNotify     result_destroy_func);
+gboolean    gimp_async_is_finished             (GimpAsync         *async);
+gpointer    gimp_async_get_result              (GimpAsync         *async);
+
+void        gimp_async_abort                   (GimpAsync         *async);
+
+gboolean    gimp_async_is_canceled             (GimpAsync         *async);
+
+void        gimp_async_cancel_and_wait         (GimpAsync         *async);
+
+
+/*  stats  */
+
+gint        gimp_async_get_n_running           (void);
+
+
+#endif /* __GIMP_ASYNC_H__ */
diff --git a/app/core/gimpasyncset.c b/app/core/gimpasyncset.c
new file mode 100644
index 0000000..f1b611e
--- /dev/null
+++ b/app/core/gimpasyncset.c
@@ -0,0 +1,348 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpasyncset.c
+ * Copyright (C) 2018 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gimpasync.h"
+#include "gimpasyncset.h"
+#include "gimpcancelable.h"
+#include "gimpwaitable.h"
+
+
+enum
+{
+  PROP_0,
+  PROP_EMPTY
+};
+
+
+struct _GimpAsyncSetPrivate
+{
+  GHashTable *asyncs;
+};
+
+
+/*  local function prototypes  */
+
+static void       gimp_async_set_waitable_iface_init   (GimpWaitableInterface   *iface);
+
+static void       gimp_async_set_cancelable_iface_init (GimpCancelableInterface *iface);
+
+static void       gimp_async_set_dispose               (GObject                 *object);
+static void       gimp_async_set_finalize              (GObject                 *object);
+static void       gimp_async_set_set_property          (GObject                 *object,
+                                                        guint                    property_id,
+                                                        const GValue            *value,
+                                                        GParamSpec              *pspec);
+static void       gimp_async_set_get_property          (GObject                 *object,
+                                                        guint                    property_id,
+                                                        GValue                  *value,
+                                                        GParamSpec              *pspec);
+
+static void       gimp_async_set_wait                  (GimpWaitable            *waitable);
+static gboolean   gimp_async_set_try_wait              (GimpWaitable            *waitable);
+static gboolean   gimp_async_set_wait_until            (GimpWaitable            *waitable,
+                                                        gint64                   end_time);
+
+static void       gimp_async_set_cancel                (GimpCancelable          *cancelable);
+
+static void       gimp_async_set_async_callback        (GimpAsync               *async,
+                                                        GimpAsyncSet            *async_set);
+
+
+G_DEFINE_TYPE_WITH_CODE (GimpAsyncSet, gimp_async_set, G_TYPE_OBJECT,
+                         G_ADD_PRIVATE (GimpAsyncSet)
+                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_WAITABLE,
+                                                gimp_async_set_waitable_iface_init)
+                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_CANCELABLE,
+                                                gimp_async_set_cancelable_iface_init))
+
+#define parent_class gimp_async_set_parent_class
+
+
+/*  private functions  */
+
+
+static void
+gimp_async_set_class_init (GimpAsyncSetClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  object_class->dispose      = gimp_async_set_dispose;
+  object_class->finalize     = gimp_async_set_finalize;
+  object_class->set_property = gimp_async_set_set_property;
+  object_class->get_property = gimp_async_set_get_property;
+
+  g_object_class_install_property (object_class, PROP_EMPTY,
+                                   g_param_spec_boolean ("empty",
+                                                         NULL, NULL,
+                                                         FALSE,
+                                                         GIMP_PARAM_READABLE));
+}
+
+static void
+gimp_async_set_waitable_iface_init (GimpWaitableInterface *iface)
+{
+  iface->wait       = gimp_async_set_wait;
+  iface->try_wait   = gimp_async_set_try_wait;
+  iface->wait_until = gimp_async_set_wait_until;
+}
+
+static void
+gimp_async_set_cancelable_iface_init (GimpCancelableInterface *iface)
+{
+  iface->cancel = gimp_async_set_cancel;
+}
+
+static void
+gimp_async_set_init (GimpAsyncSet *async_set)
+{
+  async_set->priv = gimp_async_set_get_instance_private (async_set);
+
+  async_set->priv->asyncs = g_hash_table_new (NULL, NULL);
+}
+
+static void
+gimp_async_set_dispose (GObject *object)
+{
+  GimpAsyncSet *async_set = GIMP_ASYNC_SET (object);
+
+  gimp_async_set_clear (async_set);
+
+  G_OBJECT_CLASS (parent_class)->dispose (object);
+}
+
+static void
+gimp_async_set_finalize (GObject *object)
+{
+  GimpAsyncSet *async_set = GIMP_ASYNC_SET (object);
+
+  g_hash_table_unref (async_set->priv->asyncs);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gimp_async_set_set_property (GObject      *object,
+                             guint         property_id,
+                             const GValue *value,
+                             GParamSpec   *pspec)
+{
+  switch (property_id)
+    {
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_async_set_get_property (GObject    *object,
+                             guint       property_id,
+                             GValue     *value,
+                             GParamSpec *pspec)
+{
+  GimpAsyncSet *async_set = GIMP_ASYNC_SET (object);
+
+  switch (property_id)
+    {
+    case PROP_EMPTY:
+      g_value_set_boolean (value, gimp_async_set_is_empty (async_set));
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_async_set_wait (GimpWaitable *waitable)
+{
+  GimpAsyncSet *async_set = GIMP_ASYNC_SET (waitable);
+
+  while (! gimp_async_set_is_empty (async_set))
+    {
+      GimpAsync      *async;
+      GHashTableIter  iter;
+
+      g_hash_table_iter_init (&iter, async_set->priv->asyncs);
+
+      g_hash_table_iter_next (&iter, (gpointer *) &async, NULL);
+
+      gimp_waitable_wait (GIMP_WAITABLE (async));
+    }
+}
+
+static gboolean
+gimp_async_set_try_wait (GimpWaitable *waitable)
+{
+  GimpAsyncSet *async_set = GIMP_ASYNC_SET (waitable);
+
+  while (! gimp_async_set_is_empty (async_set))
+    {
+      GimpAsync      *async;
+      GHashTableIter  iter;
+
+      g_hash_table_iter_init (&iter, async_set->priv->asyncs);
+
+      g_hash_table_iter_next (&iter, (gpointer *) &async, NULL);
+
+      if (! gimp_waitable_try_wait (GIMP_WAITABLE (async)))
+        return FALSE;
+    }
+
+  return TRUE;
+}
+
+static gboolean
+gimp_async_set_wait_until (GimpWaitable *waitable,
+                           gint64        end_time)
+{
+  GimpAsyncSet *async_set = GIMP_ASYNC_SET (waitable);
+
+  while (! gimp_async_set_is_empty (async_set))
+    {
+      GimpAsync      *async;
+      GHashTableIter  iter;
+
+      g_hash_table_iter_init (&iter, async_set->priv->asyncs);
+
+      g_hash_table_iter_next (&iter, (gpointer *) &async, NULL);
+
+      if (! gimp_waitable_wait_until (GIMP_WAITABLE (async), end_time))
+        return FALSE;
+    }
+
+  return TRUE;
+}
+
+static void
+gimp_async_set_cancel (GimpCancelable *cancelable)
+{
+  GimpAsyncSet *async_set = GIMP_ASYNC_SET (cancelable);
+  GList        *list;
+
+  list = g_hash_table_get_keys (async_set->priv->asyncs);
+
+  g_list_foreach (list, (GFunc) g_object_ref, NULL);
+
+  g_list_foreach (list, (GFunc) gimp_cancelable_cancel, NULL);
+
+  g_list_free_full (list, g_object_unref);
+}
+
+static void
+gimp_async_set_async_callback (GimpAsync    *async,
+                               GimpAsyncSet *async_set)
+{
+  g_hash_table_remove (async_set->priv->asyncs, async);
+
+  if (gimp_async_set_is_empty (async_set))
+    g_object_notify (G_OBJECT (async_set), "empty");
+}
+
+
+/*  public functions  */
+
+
+GimpAsyncSet *
+gimp_async_set_new (void)
+{
+  return g_object_new (GIMP_TYPE_ASYNC_SET,
+                       NULL);
+}
+
+void
+gimp_async_set_add (GimpAsyncSet *async_set,
+                    GimpAsync    *async)
+{
+  g_return_if_fail (GIMP_IS_ASYNC_SET (async_set));
+  g_return_if_fail (GIMP_IS_ASYNC (async));
+
+  if (g_hash_table_add (async_set->priv->asyncs, async))
+    {
+      if (g_hash_table_size (async_set->priv->asyncs) == 1)
+        g_object_notify (G_OBJECT (async_set), "empty");
+
+      gimp_async_add_callback (
+        async,
+        (GimpAsyncCallback) gimp_async_set_async_callback,
+        async_set);
+    }
+}
+
+void
+gimp_async_set_remove (GimpAsyncSet *async_set,
+                       GimpAsync    *async)
+{
+  g_return_if_fail (GIMP_IS_ASYNC_SET (async_set));
+  g_return_if_fail (GIMP_IS_ASYNC (async));
+
+  if (g_hash_table_remove (async_set->priv->asyncs, async))
+    {
+      gimp_async_remove_callback (
+        async,
+        (GimpAsyncCallback) gimp_async_set_async_callback,
+        async_set);
+
+      if (g_hash_table_size (async_set->priv->asyncs) == 0)
+        g_object_notify (G_OBJECT (async_set), "empty");
+    }
+}
+
+void
+gimp_async_set_clear (GimpAsyncSet *async_set)
+{
+  GimpAsync      *async;
+  GHashTableIter  iter;
+
+  g_return_if_fail (GIMP_IS_ASYNC_SET (async_set));
+
+  if (gimp_async_set_is_empty (async_set))
+    return;
+
+  g_hash_table_iter_init (&iter, async_set->priv->asyncs);
+
+  while (g_hash_table_iter_next (&iter, (gpointer *) &async, NULL))
+    {
+      gimp_async_remove_callback (
+        async,
+        (GimpAsyncCallback) gimp_async_set_async_callback,
+        async_set);
+    }
+
+  g_hash_table_remove_all (async_set->priv->asyncs);
+
+  g_object_notify (G_OBJECT (async_set), "empty");
+}
+
+gboolean
+gimp_async_set_is_empty (GimpAsyncSet *async_set)
+{
+  g_return_val_if_fail (GIMP_IS_ASYNC_SET (async_set), FALSE);
+
+  return g_hash_table_size (async_set->priv->asyncs) == 0;
+}
diff --git a/app/core/gimpasyncset.h b/app/core/gimpasyncset.h
new file mode 100644
index 0000000..62cc524
--- /dev/null
+++ b/app/core/gimpasyncset.h
@@ -0,0 +1,61 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpasyncset.h
+ * Copyright (C) 2018 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_ASYNC_SET_H__
+#define __GIMP_ASYNC_SET_H__
+
+
+#define GIMP_TYPE_ASYNC_SET            (gimp_async_set_get_type ())
+#define GIMP_ASYNC_SET(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_ASYNC_SET, GimpAsyncSet))
+#define GIMP_ASYNC_SET_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_ASYNC_SET, GimpAsyncSetClass))
+#define GIMP_IS_ASYNC_SET(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_ASYNC_SET))
+#define GIMP_IS_ASYNC_SET_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_ASYNC_SET))
+#define GIMP_ASYNC_SET_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_ASYNC_SET, GimpAsyncSetClass))
+
+
+typedef struct _GimpAsyncSetPrivate GimpAsyncSetPrivate;
+typedef struct _GimpAsyncSetClass   GimpAsyncSetClass;
+
+struct _GimpAsyncSet
+{
+  GObject              parent_instance;
+
+  GimpAsyncSetPrivate *priv;
+};
+
+struct _GimpAsyncSetClass
+{
+  GObjectClass  parent_class;
+};
+
+
+GType          gimp_async_set_get_type (void) G_GNUC_CONST;
+
+GimpAsyncSet * gimp_async_set_new      (void);
+
+void           gimp_async_set_add      (GimpAsyncSet *async_set,
+                                        GimpAsync    *async);
+void           gimp_async_set_remove   (GimpAsyncSet *async_set,
+                                        GimpAsync    *async);
+void           gimp_async_set_clear    (GimpAsyncSet *async_set);
+gboolean       gimp_async_set_is_empty (GimpAsyncSet *async_set);
+
+
+#endif /* __GIMP_ASYNC_SET_H__ */
diff --git a/app/core/gimpauxitem.c b/app/core/gimpauxitem.c
new file mode 100644
index 0000000..cc96149
--- /dev/null
+++ b/app/core/gimpauxitem.c
@@ -0,0 +1,147 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <glib-object.h>
+
+#include "core-types.h"
+
+#include "gimpauxitem.h"
+
+
+enum
+{
+  REMOVED,
+  LAST_SIGNAL
+};
+
+enum
+{
+  PROP_0,
+  PROP_ID
+};
+
+
+struct _GimpAuxItemPrivate
+{
+  guint32  aux_item_ID;
+};
+
+
+static void   gimp_aux_item_get_property (GObject      *object,
+                                          guint         property_id,
+                                          GValue       *value,
+                                          GParamSpec   *pspec);
+static void   gimp_aux_item_set_property (GObject      *object,
+                                          guint         property_id,
+                                          const GValue *value,
+                                          GParamSpec   *pspec);
+
+
+G_DEFINE_ABSTRACT_TYPE_WITH_PRIVATE (GimpAuxItem, gimp_aux_item, G_TYPE_OBJECT)
+
+static guint gimp_aux_item_signals[LAST_SIGNAL] = { 0 };
+
+
+static void
+gimp_aux_item_class_init (GimpAuxItemClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  gimp_aux_item_signals[REMOVED] =
+    g_signal_new ("removed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpAuxItemClass, removed),
+                  NULL, NULL,
+                  g_cclosure_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  object_class->get_property = gimp_aux_item_get_property;
+  object_class->set_property = gimp_aux_item_set_property;
+
+  klass->removed             = NULL;
+
+  g_object_class_install_property (object_class, PROP_ID,
+                                   g_param_spec_uint ("id", NULL, NULL,
+                                                      0, G_MAXUINT32, 0,
+                                                      G_PARAM_CONSTRUCT_ONLY |
+                                                      GIMP_PARAM_READWRITE));
+}
+
+static void
+gimp_aux_item_init (GimpAuxItem *aux_item)
+{
+  aux_item->priv = gimp_aux_item_get_instance_private (aux_item);
+}
+
+static void
+gimp_aux_item_get_property (GObject    *object,
+                            guint       property_id,
+                            GValue     *value,
+                            GParamSpec *pspec)
+{
+  GimpAuxItem *aux_item = GIMP_AUX_ITEM (object);
+
+  switch (property_id)
+    {
+    case PROP_ID:
+      g_value_set_uint (value, aux_item->priv->aux_item_ID);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_aux_item_set_property (GObject      *object,
+                            guint         property_id,
+                            const GValue *value,
+                            GParamSpec   *pspec)
+{
+  GimpAuxItem *aux_item = GIMP_AUX_ITEM (object);
+
+  switch (property_id)
+    {
+    case PROP_ID:
+      aux_item->priv->aux_item_ID = g_value_get_uint (value);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+guint32
+gimp_aux_item_get_ID (GimpAuxItem *aux_item)
+{
+  g_return_val_if_fail (GIMP_IS_AUX_ITEM (aux_item), 0);
+
+  return aux_item->priv->aux_item_ID;
+}
+
+void
+gimp_aux_item_removed (GimpAuxItem *aux_item)
+{
+  g_return_if_fail (GIMP_IS_AUX_ITEM (aux_item));
+
+  g_signal_emit (aux_item, gimp_aux_item_signals[REMOVED], 0);
+}
diff --git a/app/core/gimpauxitem.h b/app/core/gimpauxitem.h
new file mode 100644
index 0000000..6907b39
--- /dev/null
+++ b/app/core/gimpauxitem.h
@@ -0,0 +1,56 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_AUX_ITEM_H__
+#define __GIMP_AUX_ITEM_H__
+
+
+#define GIMP_TYPE_AUX_ITEM            (gimp_aux_item_get_type ())
+#define GIMP_AUX_ITEM(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_AUX_ITEM, GimpAuxItem))
+#define GIMP_AUX_ITEM_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_AUX_ITEM, GimpAuxItemClass))
+#define GIMP_IS_AUX_ITEM(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_AUX_ITEM))
+#define GIMP_IS_AUX_ITEM_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_AUX_ITEM))
+#define GIMP_AUX_ITEM_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_AUX_ITEM, GimpAuxItemClass))
+
+
+typedef struct _GimpAuxItemPrivate GimpAuxItemPrivate;
+typedef struct _GimpAuxItemClass   GimpAuxItemClass;
+
+struct _GimpAuxItem
+{
+  GObject             parent_instance;
+
+  GimpAuxItemPrivate *priv;
+};
+
+struct _GimpAuxItemClass
+{
+  GObjectClass  parent_class;
+
+  /*  signals  */
+  void (* removed) (GimpAuxItem *aux_item);
+};
+
+
+GType     gimp_aux_item_get_type (void) G_GNUC_CONST;
+
+guint32   gimp_aux_item_get_ID       (GimpAuxItem *aux_item);
+
+void      gimp_aux_item_removed      (GimpAuxItem *aux_item);
+
+
+#endif /* __GIMP_AUX_ITEM_H__ */
diff --git a/app/core/gimpauxitemundo.c b/app/core/gimpauxitemundo.c
new file mode 100644
index 0000000..e0253ab
--- /dev/null
+++ b/app/core/gimpauxitemundo.c
@@ -0,0 +1,138 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gimpauxitem.h"
+#include "gimpauxitemundo.h"
+
+
+enum
+{
+  PROP_0,
+  PROP_AUX_ITEM
+};
+
+
+static void   gimp_aux_item_undo_constructed  (GObject      *object);
+static void   gimp_aux_item_undo_set_property (GObject      *object,
+                                               guint         property_id,
+                                               const GValue *value,
+                                               GParamSpec   *pspec);
+static void   gimp_aux_item_undo_get_property (GObject      *object,
+                                               guint         property_id,
+                                               GValue       *value,
+                                               GParamSpec   *pspec);
+
+static void   gimp_aux_item_undo_free         (GimpUndo     *undo,
+                                               GimpUndoMode  undo_mode);
+
+
+G_DEFINE_ABSTRACT_TYPE (GimpAuxItemUndo, gimp_aux_item_undo, GIMP_TYPE_UNDO)
+
+#define parent_class gimp_aux_item_undo_parent_class
+
+
+static void
+gimp_aux_item_undo_class_init (GimpAuxItemUndoClass *klass)
+{
+  GObjectClass  *object_class = G_OBJECT_CLASS (klass);
+  GimpUndoClass *undo_class   = GIMP_UNDO_CLASS (klass);
+
+  object_class->constructed  = gimp_aux_item_undo_constructed;
+  object_class->set_property = gimp_aux_item_undo_set_property;
+  object_class->get_property = gimp_aux_item_undo_get_property;
+
+  undo_class->free           = gimp_aux_item_undo_free;
+
+  g_object_class_install_property (object_class, PROP_AUX_ITEM,
+                                   g_param_spec_object ("aux-item", NULL, NULL,
+                                                        GIMP_TYPE_AUX_ITEM,
+                                                        GIMP_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT_ONLY));
+}
+
+static void
+gimp_aux_item_undo_init (GimpAuxItemUndo *undo)
+{
+}
+
+static void
+gimp_aux_item_undo_constructed (GObject *object)
+{
+  GimpAuxItemUndo *aux_item_undo = GIMP_AUX_ITEM_UNDO (object);
+
+  G_OBJECT_CLASS (parent_class)->constructed (object);
+
+  gimp_assert (GIMP_IS_AUX_ITEM (aux_item_undo->aux_item));
+}
+
+static void
+gimp_aux_item_undo_set_property (GObject      *object,
+                                 guint         property_id,
+                                 const GValue *value,
+                                 GParamSpec   *pspec)
+{
+  GimpAuxItemUndo *aux_item_undo = GIMP_AUX_ITEM_UNDO (object);
+
+  switch (property_id)
+    {
+    case PROP_AUX_ITEM:
+      aux_item_undo->aux_item = g_value_dup_object (value);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_aux_item_undo_get_property (GObject    *object,
+                                 guint       property_id,
+                                 GValue     *value,
+                                 GParamSpec *pspec)
+{
+  GimpAuxItemUndo *aux_item_undo = GIMP_AUX_ITEM_UNDO (object);
+
+  switch (property_id)
+    {
+    case PROP_AUX_ITEM:
+      g_value_set_object (value, aux_item_undo->aux_item);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_aux_item_undo_free (GimpUndo     *undo,
+                         GimpUndoMode  undo_mode)
+{
+  GimpAuxItemUndo *aux_item_undo = GIMP_AUX_ITEM_UNDO (undo);
+
+  g_clear_object (&aux_item_undo->aux_item);
+
+  GIMP_UNDO_CLASS (parent_class)->free (undo, undo_mode);
+}
diff --git a/app/core/gimpauxitemundo.h b/app/core/gimpauxitemundo.h
new file mode 100644
index 0000000..2858f4d
--- /dev/null
+++ b/app/core/gimpauxitemundo.h
@@ -0,0 +1,52 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_AUX_ITEM_UNDO_H__
+#define __GIMP_AUX_ITEM_UNDO_H__
+
+
+#include "gimpundo.h"
+
+
+#define GIMP_TYPE_AUX_ITEM_UNDO            (gimp_aux_item_undo_get_type ())
+#define GIMP_AUX_ITEM_UNDO(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_AUX_ITEM_UNDO, GimpAuxItemUndo))
+#define GIMP_AUX_ITEM_UNDO_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_AUX_ITEM_UNDO, GimpAuxItemUndoClass))
+#define GIMP_IS_AUX_ITEM_UNDO(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_AUX_ITEM_UNDO))
+#define GIMP_IS_AUX_ITEM_UNDO_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_AUX_ITEM_UNDO))
+#define GIMP_AUX_ITEM_UNDO_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_AUX_ITEM_UNDO, GimpAuxItemUndoClass))
+
+
+typedef struct _GimpAuxItemUndo      GimpAuxItemUndo;
+typedef struct _GimpAuxItemUndoClass GimpAuxItemUndoClass;
+
+struct _GimpAuxItemUndo
+{
+  GimpUndo     parent_instance;
+
+  GimpAuxItem *aux_item;
+};
+
+struct _GimpAuxItemUndoClass
+{
+  GimpUndoClass  parent_class;
+};
+
+
+GType   gimp_aux_item_undo_get_type (void) G_GNUC_CONST;
+
+
+#endif /* __GIMP_AUX_ITEM_UNDO_H__ */
diff --git a/app/core/gimpbacktrace-backend.h b/app/core/gimpbacktrace-backend.h
new file mode 100644
index 0000000..4bfb1c9
--- /dev/null
+++ b/app/core/gimpbacktrace-backend.h
@@ -0,0 +1,34 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpbacktrace-backend.h
+ * Copyright (C) 2018 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_BACKTRACE_BACKEND_H__
+#define __GIMP_BACKTRACE_BACKEND_H__
+
+
+#ifdef __gnu_linux__
+# define GIMP_BACKTRACE_BACKEND_LINUX
+#elif defined (G_OS_WIN32) && defined (ARCH_X86)
+# define GIMP_BACKTRACE_BACKEND_WINDOWS
+#else
+# define GIMP_BACKTRACE_BACKEND_NONE
+#endif
+
+
+#endif  /*  __GIMP_BACKTRACE_BACKEND_H__  */
diff --git a/app/core/gimpbacktrace-linux.c b/app/core/gimpbacktrace-linux.c
new file mode 100644
index 0000000..a8593f8
--- /dev/null
+++ b/app/core/gimpbacktrace-linux.c
@@ -0,0 +1,725 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1999 Spencer Kimball and Peter Mattis
+ *
+ * gimpbacktrace-linux.c
+ * Copyright (C) 2018 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+
+#define _GNU_SOURCE
+
+
+#include "config.h"
+
+#include <gio/gio.h>
+
+#include "gimpbacktrace-backend.h"
+
+
+#ifdef GIMP_BACKTRACE_BACKEND_LINUX
+
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <dirent.h>
+#include <signal.h>
+#include <execinfo.h>
+#include <dlfcn.h>
+#include <string.h>
+#include <stdio.h>
+
+#ifdef HAVE_LIBBACKTRACE
+#include <backtrace.h>
+#endif
+
+#ifdef HAVE_LIBUNWIND
+#define UNW_LOCAL_ONLY
+#include <libunwind.h>
+#endif
+
+#include "core-types.h"
+
+#include "gimpbacktrace.h"
+
+
+#define MAX_N_THREADS        256
+#define MAX_N_FRAMES         256
+#define MAX_THREAD_NAME_SIZE 32
+#define N_SKIPPED_FRAMES     2
+#define MAX_WAIT_TIME        (G_TIME_SPAN_SECOND / 20)
+#define BACKTRACE_SIGNAL     SIGUSR1
+
+
+typedef struct _GimpBacktraceThread GimpBacktraceThread;
+
+
+struct _GimpBacktraceThread
+{
+  pid_t    tid;
+  gchar    name[MAX_THREAD_NAME_SIZE];
+  gchar    state;
+
+  guintptr frames[MAX_N_FRAMES];
+  gint     n_frames;
+};
+
+struct _GimpBacktrace
+{
+  GimpBacktraceThread *threads;
+  gint                 n_threads;
+};
+
+
+/*  local function prototypes  */
+
+static inline gint   gimp_backtrace_normalize_frame   (GimpBacktrace *backtrace,
+                                                       gint           thread,
+                                                       gint           frame);
+
+static gint          gimp_backtrace_enumerate_threads (gboolean       include_current_thread,
+                                                       pid_t         *threads,
+                                                       gint           size);
+static void          gimp_backtrace_read_thread_name  (pid_t          tid,
+                                                       gchar         *name,
+                                                       gint           size);
+static gchar         gimp_backtrace_read_thread_state (pid_t          tid);
+
+static void          gimp_backtrace_signal_handler    (gint           signum);
+
+
+/*  static variables  */
+
+static GMutex            mutex;
+static gint              n_initializations;
+static gboolean          initialized;
+static struct sigaction  orig_action;
+static pid_t             blacklisted_threads[MAX_N_THREADS];
+static gint              n_blacklisted_threads;
+static GimpBacktrace    *handler_backtrace;
+static gint              handler_n_remaining_threads;
+static gint              handler_lock;
+
+#ifdef HAVE_LIBBACKTRACE
+static struct backtrace_state *backtrace_state;
+#endif
+
+static const gchar * const blacklisted_thread_names[] =
+{
+  "gmain",
+  "threaded-ml"
+};
+
+
+/*  private functions  */
+
+
+static inline gint
+gimp_backtrace_normalize_frame (GimpBacktrace *backtrace,
+                                gint           thread,
+                                gint           frame)
+{
+  if (frame >= 0)
+    return frame + N_SKIPPED_FRAMES;
+  else
+    return backtrace->threads[thread].n_frames + frame;
+}
+
+static gint
+gimp_backtrace_enumerate_threads (gboolean  include_current_thread,
+                                  pid_t    *threads,
+                                  gint      size)
+{
+  DIR           *dir;
+  struct dirent *dirent;
+  pid_t          tid;
+  gint           n_threads;
+
+  dir = opendir ("/proc/self/task");
+
+  if (! dir)
+    return 0;
+
+  tid = syscall (SYS_gettid);
+
+  n_threads = 0;
+
+  while (n_threads < size && (dirent = readdir (dir)))
+    {
+      pid_t id = g_ascii_strtoull (dirent->d_name, NULL, 10);
+
+      if (id)
+        {
+          if (! include_current_thread && id == tid)
+            id = 0;
+        }
+
+      if (id)
+        {
+          gint i;
+
+          for (i = 0; i < n_blacklisted_threads; i++)
+            {
+              if (id == blacklisted_threads[i])
+                {
+                  id = 0;
+
+                  break;
+                }
+            }
+        }
+
+      if (id)
+        threads[n_threads++] = id;
+    }
+
+  closedir (dir);
+
+  return n_threads;
+}
+
+static void
+gimp_backtrace_read_thread_name (pid_t  tid,
+                                 gchar *name,
+                                 gint   size)
+{
+  gchar filename[64];
+  gint  fd;
+
+  if (size <= 0)
+    return;
+
+  name[0] = '\0';
+
+  g_snprintf (filename, sizeof (filename),
+              "/proc/self/task/%llu/comm",
+              (unsigned long long) tid);
+
+  fd = open (filename, O_RDONLY);
+
+  if (fd >= 0)
+    {
+      gint n = read (fd, name, size);
+
+      if (n > 0)
+        name[n - 1] = '\0';
+
+      close (fd);
+    }
+}
+
+static gchar
+gimp_backtrace_read_thread_state (pid_t tid)
+{
+  gchar buffer[64];
+  gint  fd;
+  gchar state = '\0';
+
+  g_snprintf (buffer, sizeof (buffer),
+              "/proc/self/task/%llu/stat",
+              (unsigned long long) tid);
+
+  fd = open (buffer, O_RDONLY);
+
+  if (fd >= 0)
+    {
+      gint n = read (fd, buffer, sizeof (buffer));
+
+      if (n > 0)
+        buffer[n - 1] = '\0';
+
+      sscanf (buffer, "%*d %*s %c", &state);
+
+      close (fd);
+    }
+
+  return state;
+}
+
+static void
+gimp_backtrace_signal_handler (gint signum)
+{
+  GimpBacktrace *curr_backtrace;
+  gint           lock;
+
+  do
+    {
+      lock = g_atomic_int_get (&handler_lock);
+
+      if (lock < 0)
+        continue;
+    }
+  while (! g_atomic_int_compare_and_exchange (&handler_lock, lock, lock + 1));
+
+  curr_backtrace = g_atomic_pointer_get (&handler_backtrace);
+
+  if (curr_backtrace)
+    {
+      pid_t tid = syscall (SYS_gettid);
+      gint  i;
+
+      for (i = 0; i < curr_backtrace->n_threads; i++)
+        {
+          GimpBacktraceThread *thread = &curr_backtrace->threads[i];
+
+          if (thread->tid == tid)
+            {
+              thread->n_frames = backtrace ((gpointer *) thread->frames,
+                                            MAX_N_FRAMES);
+
+              g_atomic_int_dec_and_test (&handler_n_remaining_threads);
+
+              break;
+            }
+        }
+    }
+
+  g_atomic_int_dec_and_test (&handler_lock);
+}
+
+
+/*  public functions  */
+
+
+void
+gimp_backtrace_init (void)
+{
+#ifdef HAVE_LIBBACKTRACE
+  backtrace_state = backtrace_create_state (NULL, 0, NULL, NULL);
+#endif
+}
+
+gboolean
+gimp_backtrace_start (void)
+{
+  g_mutex_lock (&mutex);
+
+  if (n_initializations == 0)
+    {
+      struct sigaction action = {};
+
+      action.sa_handler = gimp_backtrace_signal_handler;
+      action.sa_flags   = SA_RESTART;
+
+      sigemptyset (&action.sa_mask);
+
+      if (sigaction (BACKTRACE_SIGNAL, &action, &orig_action) == 0)
+        {
+          pid_t *threads;
+          gint   n_threads;
+          gint   i;
+
+          n_blacklisted_threads = 0;
+
+          threads = g_new (pid_t, MAX_N_THREADS);
+
+          n_threads = gimp_backtrace_enumerate_threads (TRUE,
+                                                        threads, MAX_N_THREADS);
+
+          for (i = 0; i < n_threads; i++)
+            {
+              gchar name[MAX_THREAD_NAME_SIZE];
+              gint  j;
+
+              gimp_backtrace_read_thread_name (threads[i],
+                                               name, MAX_THREAD_NAME_SIZE);
+
+              for (j = 0; j < G_N_ELEMENTS (blacklisted_thread_names); j++)
+                {
+                  if (! strcmp (name, blacklisted_thread_names[j]))
+                    {
+                      blacklisted_threads[n_blacklisted_threads++] = threads[i];
+                    }
+                }
+            }
+
+          g_free (threads);
+
+          initialized = TRUE;
+        }
+    }
+
+  n_initializations++;
+
+  g_mutex_unlock (&mutex);
+
+  return initialized;
+}
+
+void
+gimp_backtrace_stop (void)
+{
+  g_return_if_fail (n_initializations > 0);
+
+  g_mutex_lock (&mutex);
+
+  n_initializations--;
+
+  if (n_initializations == 0 && initialized)
+    {
+      if (sigaction (BACKTRACE_SIGNAL, &orig_action, NULL) < 0)
+        g_warning ("failed to restore origianl backtrace signal handler");
+
+      initialized = FALSE;
+    }
+
+  g_mutex_unlock (&mutex);
+}
+
+GimpBacktrace *
+gimp_backtrace_new (gboolean include_current_thread)
+{
+  GimpBacktrace *backtrace;
+  pid_t          pid;
+  pid_t         *threads;
+  gint           n_threads;
+  gint64         start_time;
+  gint           i;
+
+  if (! initialized)
+    return NULL;
+
+  pid = getpid ();
+
+  threads = g_new (pid_t, MAX_N_THREADS);
+
+  n_threads = gimp_backtrace_enumerate_threads (include_current_thread,
+                                                threads, MAX_N_THREADS);
+
+  if (n_threads == 0)
+    {
+      g_free (threads);
+
+      return NULL;
+    }
+
+  g_mutex_lock (&mutex);
+
+  backtrace = g_slice_new (GimpBacktrace);
+
+  backtrace->threads   = g_new (GimpBacktraceThread, n_threads);
+  backtrace->n_threads = n_threads;
+
+  while (! g_atomic_int_compare_and_exchange (&handler_lock, 0, -1));
+
+  g_atomic_pointer_set (&handler_backtrace,           backtrace);
+  g_atomic_int_set     (&handler_n_remaining_threads, n_threads);
+
+  g_atomic_int_set (&handler_lock, 0);
+
+  for (i = 0; i < n_threads; i++)
+    {
+      GimpBacktraceThread *thread = &backtrace->threads[i];
+
+      thread->tid      = threads[i];
+      thread->n_frames = 0;
+
+      gimp_backtrace_read_thread_name (thread->tid,
+                                       thread->name, MAX_THREAD_NAME_SIZE);
+
+      thread->state = gimp_backtrace_read_thread_state (thread->tid);
+
+      syscall (SYS_tgkill, pid, threads[i], BACKTRACE_SIGNAL);
+    }
+
+  g_free (threads);
+
+  start_time = g_get_monotonic_time ();
+
+  while (g_atomic_int_get (&handler_n_remaining_threads) > 0)
+    {
+      gint64 time = g_get_monotonic_time ();
+
+      if (time - start_time > MAX_WAIT_TIME)
+        break;
+
+      g_usleep (1000);
+    }
+
+  while (! g_atomic_int_compare_and_exchange (&handler_lock, 0, -1));
+
+  g_atomic_pointer_set (&handler_backtrace, NULL);
+
+  g_atomic_int_set (&handler_lock, 0);
+
+#if 0
+  if (handler_n_remaining_threads > 0)
+    {
+      gint j = 0;
+
+      for (i = 0; i < n_threads; i++)
+        {
+          if (backtrace->threads[i].n_frames == 0)
+            {
+              if (n_blacklisted_threads < MAX_N_THREADS)
+                {
+                  blacklisted_threads[n_blacklisted_threads++] =
+                    backtrace->threads[i].tid;
+                }
+            }
+          else
+            {
+              if (j < i)
+                backtrace->threads[j] = backtrace->threads[i];
+
+              j++;
+            }
+        }
+
+      n_threads = j;
+    }
+#endif
+
+  g_mutex_unlock (&mutex);
+
+  if (n_threads == 0)
+    {
+      gimp_backtrace_free (backtrace);
+
+      return NULL;
+    }
+
+  return backtrace;
+}
+
+void
+gimp_backtrace_free (GimpBacktrace *backtrace)
+{
+  if (! backtrace)
+    return;
+
+  g_free (backtrace->threads);
+
+  g_slice_free (GimpBacktrace, backtrace);
+}
+
+gint
+gimp_backtrace_get_n_threads (GimpBacktrace *backtrace)
+{
+  g_return_val_if_fail (backtrace != NULL, 0);
+
+  return backtrace->n_threads;
+}
+
+guintptr
+gimp_backtrace_get_thread_id (GimpBacktrace *backtrace,
+                              gint           thread)
+{
+  g_return_val_if_fail (backtrace != NULL, 0);
+  g_return_val_if_fail (thread >= 0 && thread < backtrace->n_threads, 0);
+
+  return backtrace->threads[thread].tid;
+}
+
+const gchar *
+gimp_backtrace_get_thread_name (GimpBacktrace *backtrace,
+                                gint           thread)
+{
+  g_return_val_if_fail (backtrace != NULL, NULL);
+  g_return_val_if_fail (thread >= 0 && thread < backtrace->n_threads, NULL);
+
+  if (backtrace->threads[thread].name[0])
+    return backtrace->threads[thread].name;
+  else
+    return NULL;
+}
+
+gboolean
+gimp_backtrace_is_thread_running (GimpBacktrace *backtrace,
+                                  gint           thread)
+{
+  g_return_val_if_fail (backtrace != NULL, FALSE);
+  g_return_val_if_fail (thread >= 0 && thread < backtrace->n_threads, FALSE);
+
+  return backtrace->threads[thread].state == 'R';
+}
+
+gint
+gimp_backtrace_find_thread_by_id (GimpBacktrace *backtrace,
+                                  guintptr       thread_id,
+                                  gint           thread_hint)
+{
+  pid_t tid = thread_id;
+  gint  i;
+
+  g_return_val_if_fail (backtrace != NULL, -1);
+
+  if (thread_hint >= 0                    &&
+      thread_hint <  backtrace->n_threads &&
+      backtrace->threads[thread_hint].tid == tid)
+    {
+      return thread_hint;
+    }
+
+  for (i = 0; i < backtrace->n_threads; i++)
+    {
+      if (backtrace->threads[i].tid == tid)
+        return i;
+    }
+
+  return -1;
+}
+
+gint
+gimp_backtrace_get_n_frames (GimpBacktrace *backtrace,
+                             gint           thread)
+{
+  g_return_val_if_fail (backtrace != NULL, 0);
+  g_return_val_if_fail (thread >= 0 && thread < backtrace->n_threads, 0);
+
+  return MAX (backtrace->threads[thread].n_frames - N_SKIPPED_FRAMES, 0);
+}
+
+guintptr
+gimp_backtrace_get_frame_address (GimpBacktrace *backtrace,
+                                  gint           thread,
+                                  gint           frame)
+{
+  g_return_val_if_fail (backtrace != NULL, 0);
+  g_return_val_if_fail (thread >= 0 && thread < backtrace->n_threads, 0);
+
+  frame = gimp_backtrace_normalize_frame (backtrace, thread, frame);
+
+  g_return_val_if_fail (frame >= N_SKIPPED_FRAMES &&
+                        frame <  backtrace->threads[thread].n_frames, 0);
+
+  return backtrace->threads[thread].frames[frame];
+}
+
+#ifdef HAVE_LIBBACKTRACE
+static void
+gimp_backtrace_syminfo_callback (GimpBacktraceAddressInfo *info,
+                                 guintptr                  pc,
+                                 const gchar              *symname,
+                                 guintptr                  symval,
+                                 guintptr                  symsize)
+{
+  if (symname)
+    g_strlcpy (info->symbol_name, symname, sizeof (info->symbol_name));
+
+  info->symbol_address = symval;
+}
+
+static gint
+gimp_backtrace_pcinfo_callback (GimpBacktraceAddressInfo *info,
+                                guintptr                  pc,
+                                const gchar              *filename,
+                                gint                      lineno,
+                                const gchar              *function)
+{
+  if (function)
+    g_strlcpy (info->symbol_name, function, sizeof (info->symbol_name));
+
+  if (filename)
+    g_strlcpy (info->source_file, filename, sizeof (info->source_file));
+
+  info->source_line = lineno;
+
+  return 0;
+}
+#endif /* HAVE_LIBBACKTRACE */
+
+gboolean
+gimp_backtrace_get_address_info (guintptr                  address,
+                                 GimpBacktraceAddressInfo *info)
+{
+  Dl_info  dl_info;
+  gboolean result = FALSE;
+
+  g_return_val_if_fail (info != NULL, FALSE);
+
+  info->object_name[0] = '\0';
+
+  info->symbol_name[0] = '\0';
+  info->symbol_address = 0;
+
+  info->source_file[0] = '\0';
+  info->source_line    = 0;
+
+  if (dladdr ((gpointer) address, &dl_info))
+    {
+      if (dl_info.dli_fname)
+        {
+          g_strlcpy (info->object_name, dl_info.dli_fname,
+                     sizeof (info->object_name));
+        }
+
+      if (dl_info.dli_sname)
+        {
+          g_strlcpy (info->symbol_name, dl_info.dli_sname,
+                     sizeof (info->symbol_name));
+        }
+
+      info->symbol_address = (guintptr) dl_info.dli_saddr;
+
+      result = TRUE;
+    }
+
+#ifdef HAVE_LIBBACKTRACE
+  if (backtrace_state)
+    {
+      backtrace_syminfo (
+        backtrace_state, address,
+        (backtrace_syminfo_callback) gimp_backtrace_syminfo_callback,
+        NULL,
+        info);
+
+      backtrace_pcinfo (
+        backtrace_state, address,
+        (backtrace_full_callback) gimp_backtrace_pcinfo_callback,
+        NULL,
+        info);
+
+      result = TRUE;
+    }
+#endif /* HAVE_LIBBACKTRACE */
+
+#ifdef HAVE_LIBUNWIND
+/* we use libunwind to get the symbol name, when available, even if dladdr() or
+ * libbacktrace already found one, since it provides more descriptive names in
+ * some cases, and, in particular, full symbol names for C++ lambdas.
+ *
+ * note that, in some cases, this can result in a discrepancy between the
+ * symbol name, and the corresponding source location.
+ */
+#if 0
+  if (! info->symbol_name[0])
+#endif
+    {
+      unw_context_t context = {};
+      unw_cursor_t  cursor;
+      unw_word_t    offset;
+
+      if (unw_init_local (&cursor, &context)         == 0 &&
+          unw_set_reg (&cursor, UNW_REG_IP, address) == 0 &&
+          unw_get_proc_name (&cursor,
+                             info->symbol_name, sizeof (info->symbol_name),
+                             &offset)                == 0)
+        {
+          info->symbol_address = address - offset;
+
+          result = TRUE;
+        }
+    }
+#endif /* HAVE_LIBUNWIND */
+
+  return result;
+}
+
+
+#endif /* GIMP_BACKTRACE_BACKEND_LINUX */
diff --git a/app/core/gimpbacktrace-none.c b/app/core/gimpbacktrace-none.c
new file mode 100644
index 0000000..087e8cb
--- /dev/null
+++ b/app/core/gimpbacktrace-none.c
@@ -0,0 +1,126 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1999 Spencer Kimball and Peter Mattis
+ *
+ * gimpbacktrace-none.c
+ * Copyright (C) 2018 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+
+#include "config.h"
+
+#include <gio/gio.h>
+
+#include "gimpbacktrace-backend.h"
+
+
+#ifdef GIMP_BACKTRACE_BACKEND_NONE
+
+
+#include "core-types.h"
+
+#include "gimpbacktrace.h"
+
+
+/*  public functions  */
+
+
+void
+gimp_backtrace_init (void)
+{
+}
+
+gboolean
+gimp_backtrace_start (void)
+{
+  return FALSE;
+}
+
+void
+gimp_backtrace_stop (void)
+{
+}
+
+GimpBacktrace *
+gimp_backtrace_new (gboolean include_current_thread)
+{
+  return NULL;
+}
+
+void
+gimp_backtrace_free (GimpBacktrace *backtrace)
+{
+  g_return_if_fail (backtrace == NULL);
+}
+
+gint
+gimp_backtrace_get_n_threads (GimpBacktrace *backtrace)
+{
+  g_return_val_if_reached (0);
+}
+
+guintptr
+gimp_backtrace_get_thread_id (GimpBacktrace *backtrace,
+                              gint           thread)
+{
+  g_return_val_if_reached (0);
+}
+
+const gchar *
+gimp_backtrace_get_thread_name (GimpBacktrace *backtrace,
+                                gint           thread)
+{
+  g_return_val_if_reached (NULL);
+}
+
+gboolean
+gimp_backtrace_is_thread_running (GimpBacktrace *backtrace,
+                                  gint           thread)
+{
+  g_return_val_if_reached (FALSE);
+}
+
+gint
+gimp_backtrace_find_thread_by_id (GimpBacktrace *backtrace,
+                                  guintptr       thread_id,
+                                  gint           thread_hint)
+{
+  g_return_val_if_reached (-1);
+}
+
+gint
+gimp_backtrace_get_n_frames (GimpBacktrace *backtrace,
+                             gint           thread)
+{
+  g_return_val_if_reached (0);
+}
+
+guintptr
+gimp_backtrace_get_frame_address (GimpBacktrace *backtrace,
+                                  gint           thread,
+                                  gint           frame)
+{
+  g_return_val_if_reached (0);
+}
+
+gboolean
+gimp_backtrace_get_address_info (guintptr                  address,
+                                 GimpBacktraceAddressInfo *info)
+{
+  return FALSE;
+}
+
+
+#endif /* GIMP_BACKTRACE_BACKEND_NONE */
diff --git a/app/core/gimpbacktrace-windows.c b/app/core/gimpbacktrace-windows.c
new file mode 100644
index 0000000..da1fb73
--- /dev/null
+++ b/app/core/gimpbacktrace-windows.c
@@ -0,0 +1,706 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1999 Spencer Kimball and Peter Mattis
+ *
+ * gimpbacktrace-windows.c
+ * Copyright (C) 2018 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+
+#include "config.h"
+
+#include <gio/gio.h>
+
+#include "gimpbacktrace-backend.h"
+
+
+#ifdef GIMP_BACKTRACE_BACKEND_WINDOWS
+
+
+#include <windows.h>
+#include <psapi.h>
+#include <tlhelp32.h>
+#include <dbghelp.h>
+
+#include <string.h>
+
+#include "core-types.h"
+
+#include "gimpbacktrace.h"
+
+
+#define MAX_N_THREADS               256
+#define MAX_N_FRAMES                256
+#define THREAD_ENUMERATION_INTERVAL G_TIME_SPAN_SECOND
+
+
+typedef struct _Thread              Thread;
+typedef struct _GimpBacktraceThread GimpBacktraceThread;
+
+
+struct _Thread
+{
+  DWORD  tid;
+
+  union
+  {
+    gchar   *name;
+    guint64  time;
+  };
+};
+
+struct _GimpBacktraceThread
+{
+  DWORD        tid;
+  const gchar *name;
+  guint64      time;
+  guint64      last_time;
+
+  guintptr     frames[MAX_N_FRAMES];
+  gint         n_frames;
+};
+
+struct _GimpBacktrace
+{
+  GimpBacktraceThread *threads;
+  gint                 n_threads;
+};
+
+
+/*  local function prototypes  */
+
+static inline gint   gimp_backtrace_normalize_frame   (GimpBacktrace       *backtrace,
+                                                       gint                 thread,
+                                                       gint                 frame);
+
+static void          gimp_backtrace_set_thread_name   (DWORD                tid,
+                                                       const gchar         *name);
+
+static gboolean      gimp_backtrace_enumerate_threads (void);
+
+static LONG WINAPI   gimp_backtrace_exception_handler (PEXCEPTION_POINTERS  info);
+
+
+/*  static variables  */
+
+static GMutex    mutex;
+static gint      n_initializations;
+static gboolean  initialized;
+Thread           threads[MAX_N_THREADS];
+gint             n_threads;
+gint64           last_thread_enumeration_time;
+Thread           thread_names[MAX_N_THREADS];
+gint             n_thread_names;
+gint             thread_names_spinlock;
+Thread           thread_times[MAX_N_THREADS];
+gint             n_thread_times;
+
+DWORD   WINAPI (* gimp_backtrace_SymSetOptions)        (DWORD            SymOptions);
+BOOL    WINAPI (* gimp_backtrace_SymInitialize)        (HANDLE           hProcess,
+                                                        PCSTR            UserSearchPath,
+                                                        BOOL             fInvadeProcess);
+BOOL    WINAPI (* gimp_backtrace_SymCleanup)           (HANDLE           hProcess);
+BOOL    WINAPI (* gimp_backtrace_SymFromAddr)          (HANDLE           hProcess,
+                                                        DWORD64          Address,
+                                                        PDWORD64         Displacement,
+                                                        PSYMBOL_INFO     Symbol);
+BOOL    WINAPI (* gimp_backtrace_SymGetLineFromAddr64) (HANDLE           hProcess,
+                                                        DWORD64          qwAddr,
+                                                        PDWORD           pdwDisplacement,
+                                                        PIMAGEHLP_LINE64 Line64);
+
+
+/*  private functions  */
+
+
+static inline gint
+gimp_backtrace_normalize_frame (GimpBacktrace *backtrace,
+                                gint           thread,
+                                gint           frame)
+{
+  if (frame >= 0)
+    return frame;
+  else
+    return backtrace->threads[thread].n_frames + frame;
+}
+
+static void
+gimp_backtrace_set_thread_name (DWORD        tid,
+                                const gchar *name)
+{
+  while (! g_atomic_int_compare_and_exchange (&thread_names_spinlock,
+                                              0, 1));
+
+  if (n_thread_names < MAX_N_THREADS)
+    {
+      Thread *thread = &thread_names[n_thread_names++];
+
+      thread->tid  = tid;
+      thread->name = g_strdup (name);
+    }
+
+  g_atomic_int_set (&thread_names_spinlock, 0);
+}
+
+static gboolean
+gimp_backtrace_enumerate_threads (void)
+{
+  HANDLE        hThreadSnap;
+  THREADENTRY32 te32;
+  DWORD         pid;
+  gint64        time;
+
+  time = g_get_monotonic_time ();
+
+  if (time - last_thread_enumeration_time < THREAD_ENUMERATION_INTERVAL)
+    return n_threads > 0;
+
+  last_thread_enumeration_time = time;
+
+  n_threads = 0;
+
+  hThreadSnap = CreateToolhelp32Snapshot (TH32CS_SNAPTHREAD, 0);
+
+  if (hThreadSnap == INVALID_HANDLE_VALUE)
+    return FALSE;
+
+  te32.dwSize = sizeof (te32);
+
+  if (! Thread32First (hThreadSnap, &te32))
+    {
+      CloseHandle (hThreadSnap);
+
+      return FALSE;
+    }
+
+  pid = GetCurrentProcessId ();
+
+  while (! g_atomic_int_compare_and_exchange (&thread_names_spinlock, 0, 1));
+
+  do
+    {
+      if (n_threads == MAX_N_THREADS)
+        break;
+
+      if (te32.th32OwnerProcessID == pid)
+        {
+          Thread *thread = &threads[n_threads++];
+          gint    i;
+
+          thread->tid  = te32.th32ThreadID;
+          thread->name = NULL;
+
+          for (i = n_thread_names - 1; i >= 0; i--)
+            {
+              if (thread->tid == thread_names[i].tid)
+                {
+                  thread->name = thread_names[i].name;
+
+                  break;
+                }
+            }
+        }
+    }
+  while (Thread32Next (hThreadSnap, &te32));
+
+  g_atomic_int_set (&thread_names_spinlock, 0);
+
+  CloseHandle (hThreadSnap);
+
+  return n_threads > 0;
+}
+
+static LONG WINAPI
+gimp_backtrace_exception_handler (PEXCEPTION_POINTERS info)
+{
+  #define EXCEPTION_SET_THREAD_NAME ((DWORD) 0x406D1388)
+
+  typedef struct _THREADNAME_INFO
+  {
+    DWORD  dwType;	    /* must be 0x1000                        */
+    LPCSTR szName;	    /* pointer to name (in user addr space)  */
+    DWORD  dwThreadID;	/* thread ID (-1=caller thread)          */
+    DWORD  dwFlags;	    /* reserved for future use, must be zero */
+  } THREADNAME_INFO;
+
+  if (info->ExceptionRecord                   != NULL                      &&
+      info->ExceptionRecord->ExceptionCode    == EXCEPTION_SET_THREAD_NAME &&
+      info->ExceptionRecord->NumberParameters * 
+      sizeof (ULONG_PTR)                      == sizeof (THREADNAME_INFO))
+    {
+      THREADNAME_INFO name_info;
+
+      memcpy (&name_info, info->ExceptionRecord->ExceptionInformation,
+              sizeof (name_info));
+
+      if (name_info.dwType == 0x1000)
+        {
+          DWORD tid = name_info.dwThreadID;
+
+          if (tid == -1)
+            tid = GetCurrentThreadId ();
+
+          gimp_backtrace_set_thread_name (tid, name_info.szName);
+
+          return EXCEPTION_CONTINUE_EXECUTION;
+        }
+    }
+
+  return EXCEPTION_CONTINUE_SEARCH;
+
+  #undef EXCEPTION_SET_THREAD_NAME
+}
+
+
+/*  public functions  */
+
+
+void
+gimp_backtrace_init (void)
+{
+  gimp_backtrace_set_thread_name (GetCurrentThreadId (), g_get_prgname ());
+
+  AddVectoredExceptionHandler (TRUE, gimp_backtrace_exception_handler);
+}
+
+gboolean
+gimp_backtrace_start (void)
+{
+  g_mutex_lock (&mutex);
+
+  if (n_initializations == 0)
+    {
+      HMODULE hModule;
+      DWORD   options;
+
+      hModule = LoadLibraryA ("mgwhelp.dll");
+
+      #define INIT_PROC(name)                                    \
+        G_STMT_START                                             \
+          {                                                      \
+            gimp_backtrace_##name = name;                        \
+                                                                 \
+            if (hModule)                                         \
+              {                                                  \
+                gpointer proc = GetProcAddress (hModule, #name); \
+                                                                 \
+                if (proc)                                        \
+                  gimp_backtrace_##name = proc;                  \
+              }                                                  \
+          }                                                      \
+        G_STMT_END
+
+      INIT_PROC (SymSetOptions);
+      INIT_PROC (SymInitialize);
+      INIT_PROC (SymCleanup);
+      INIT_PROC (SymFromAddr);
+      INIT_PROC (SymGetLineFromAddr64);
+
+      #undef INIT_PROC
+
+      options = SymGetOptions ();
+
+      options &= ~SYMOPT_UNDNAME;
+      options |= SYMOPT_OMAP_FIND_NEAREST |
+                 SYMOPT_DEFERRED_LOADS    |
+                 SYMOPT_DEBUG;
+
+#ifdef ARCH_X86_64
+      options |= SYMOPT_INCLUDE_32BIT_MODULES;
+#endif
+
+      gimp_backtrace_SymSetOptions (options);
+
+      if (gimp_backtrace_SymInitialize (GetCurrentProcess (), NULL, TRUE))
+        {
+          n_threads                    = 0;
+          last_thread_enumeration_time = 0;
+          n_thread_times               = 0;
+
+          initialized = TRUE;
+        }
+    }
+
+  n_initializations++;
+
+  g_mutex_unlock (&mutex);
+
+  return initialized;
+}
+
+void
+gimp_backtrace_stop (void)
+{
+  g_return_if_fail (n_initializations > 0);
+
+  g_mutex_lock (&mutex);
+
+  n_initializations--;
+
+  if (n_initializations == 0)
+    {
+      if (initialized)
+        {
+          gimp_backtrace_SymCleanup (GetCurrentProcess ());
+
+          initialized = FALSE;
+        }
+    }
+
+  g_mutex_unlock (&mutex);
+}
+
+GimpBacktrace *
+gimp_backtrace_new (gboolean include_current_thread)
+{
+  GimpBacktrace *backtrace;
+  HANDLE         hProcess;
+  DWORD          tid;
+  gint           i;
+
+  if (! initialized)
+    return NULL;
+
+  g_mutex_lock (&mutex);
+
+  if (! gimp_backtrace_enumerate_threads ())
+    {
+      g_mutex_unlock (&mutex);
+
+      return NULL;
+    }
+
+  hProcess = GetCurrentProcess ();
+  tid      = GetCurrentThreadId ();
+
+  backtrace = g_slice_new (GimpBacktrace);
+
+  backtrace->threads   = g_new (GimpBacktraceThread, n_threads);
+  backtrace->n_threads = 0;
+
+  for (i = 0; i < n_threads; i++)
+    {
+      GimpBacktraceThread *thread  = &backtrace->threads[backtrace->n_threads];
+      HANDLE               hThread;
+      CONTEXT              context = {};
+      STACKFRAME64         frame   = {};
+      DWORD                machine_type;
+      FILETIME             creation_time;
+      FILETIME             exit_time;
+      FILETIME             kernel_time;
+      FILETIME             user_time;
+
+      if (! include_current_thread && threads[i].tid == tid)
+        continue;
+
+      hThread = OpenThread (THREAD_QUERY_INFORMATION |
+                            THREAD_GET_CONTEXT       |
+                            THREAD_SUSPEND_RESUME,
+                            FALSE,
+                            threads[i].tid);
+
+      if (hThread == INVALID_HANDLE_VALUE)
+        continue;
+
+      if (threads[i].tid != tid && SuspendThread (hThread) == (DWORD) -1)
+        {
+          CloseHandle (hThread);
+
+          continue;
+        }
+
+      context.ContextFlags = CONTEXT_FULL;
+
+      if (! GetThreadContext (hThread, &context))
+        {
+          if (threads[i].tid != tid)
+            ResumeThread (hThread);
+
+          CloseHandle (hThread);
+
+          continue;
+        }
+
+#ifdef ARCH_X86_64
+      machine_type = IMAGE_FILE_MACHINE_AMD64;
+      frame.AddrPC.Offset    = context.Rip;
+      frame.AddrPC.Mode      = AddrModeFlat;
+      frame.AddrStack.Offset = context.Rsp;
+      frame.AddrStack.Mode   = AddrModeFlat;
+      frame.AddrFrame.Offset = context.Rbp;
+      frame.AddrFrame.Mode   = AddrModeFlat;
+#elif defined (ARCH_X86)
+      machine_type = IMAGE_FILE_MACHINE_I386;
+      frame.AddrPC.Offset    = context.Eip;
+      frame.AddrPC.Mode      = AddrModeFlat;
+      frame.AddrStack.Offset = context.Esp;
+      frame.AddrStack.Mode   = AddrModeFlat;
+      frame.AddrFrame.Offset = context.Ebp;
+      frame.AddrFrame.Mode   = AddrModeFlat;
+#else
+#error unsupported architecture
+#endif
+
+      thread->tid       = threads[i].tid;
+      thread->name      = threads[i].name;
+      thread->last_time = 0;
+      thread->time      = 0;
+
+      thread->n_frames = 0;
+
+      while (thread->n_frames < MAX_N_FRAMES &&
+             StackWalk64 (machine_type, hProcess, hThread, &frame, &context,
+                          NULL,
+                          SymFunctionTableAccess64,
+                          SymGetModuleBase64,
+                          NULL))
+        {
+          thread->frames[thread->n_frames++] = frame.AddrPC.Offset;
+
+          if (frame.AddrPC.Offset == frame.AddrReturn.Offset)
+            break;
+        }
+
+      if (GetThreadTimes (hThread,
+                          &creation_time, &exit_time,
+                          &kernel_time, &user_time))
+        {
+          thread->time = (((guint64) kernel_time.dwHighDateTime << 32) |
+                          ((guint64) kernel_time.dwLowDateTime))       +
+                         (((guint64) user_time.dwHighDateTime   << 32) |
+                          ((guint64) user_time.dwLowDateTime));
+
+          if (i < n_thread_times && thread->tid == thread_times[i].tid)
+            {
+              thread->last_time = thread_times[i].time;
+            }
+          else
+            {
+              gint j;
+
+              for (j = 0; j < n_thread_times; j++)
+                {
+                  if (thread->tid == thread_times[j].tid)
+                    {
+                      thread->last_time = thread_times[j].time;
+
+                      break;
+                    }
+                }
+            }
+        }
+
+      if (threads[i].tid != tid)
+        ResumeThread (hThread);
+
+      CloseHandle (hThread);
+
+      if (thread->n_frames > 0)
+        backtrace->n_threads++;
+    }
+
+  n_thread_times = backtrace->n_threads;
+
+  for (i = 0; i < backtrace->n_threads; i++)
+    {
+      thread_times[i].tid  = backtrace->threads[i].tid;
+      thread_times[i].time = backtrace->threads[i].time;
+    }
+
+  g_mutex_unlock (&mutex);
+
+  if (backtrace->n_threads == 0)
+    {
+      gimp_backtrace_free (backtrace);
+
+      return NULL;
+    }
+
+  return backtrace;
+}
+
+void
+gimp_backtrace_free (GimpBacktrace *backtrace)
+{
+  if (backtrace)
+    {
+      g_free (backtrace->threads);
+
+      g_slice_free (GimpBacktrace, backtrace);
+    }
+}
+
+gint
+gimp_backtrace_get_n_threads (GimpBacktrace *backtrace)
+{
+  g_return_val_if_fail (backtrace != NULL, 0);
+
+  return backtrace->n_threads;
+}
+
+guintptr
+gimp_backtrace_get_thread_id (GimpBacktrace *backtrace,
+                              gint           thread)
+{
+  g_return_val_if_fail (backtrace != NULL, 0);
+  g_return_val_if_fail (thread >= 0 && thread < backtrace->n_threads, 0);
+
+  return backtrace->threads[thread].tid;
+}
+
+const gchar *
+gimp_backtrace_get_thread_name (GimpBacktrace *backtrace,
+                                gint           thread)
+{
+  g_return_val_if_fail (backtrace != NULL, NULL);
+  g_return_val_if_fail (thread >= 0 && thread < backtrace->n_threads, NULL);
+
+  return backtrace->threads[thread].name;
+}
+
+gboolean
+gimp_backtrace_is_thread_running (GimpBacktrace *backtrace,
+                                  gint           thread)
+{
+  g_return_val_if_fail (backtrace != NULL, FALSE);
+  g_return_val_if_fail (thread >= 0 && thread < backtrace->n_threads, FALSE);
+
+  return backtrace->threads[thread].time >
+         backtrace->threads[thread].last_time;
+}
+
+gint
+gimp_backtrace_find_thread_by_id (GimpBacktrace *backtrace,
+                                  guintptr       thread_id,
+                                  gint           thread_hint)
+{
+  DWORD tid = thread_id;
+  gint  i;
+
+  g_return_val_if_fail (backtrace != NULL, -1);
+
+  if (thread_hint >= 0                    &&
+      thread_hint <  backtrace->n_threads &&
+      backtrace->threads[thread_hint].tid == tid)
+    {
+      return thread_hint;
+    }
+
+  for (i = 0; i < backtrace->n_threads; i++)
+    {
+      if (backtrace->threads[i].tid == tid)
+        return i;
+    }
+
+  return -1;
+}
+
+gint
+gimp_backtrace_get_n_frames (GimpBacktrace *backtrace,
+                             gint           thread)
+{
+  g_return_val_if_fail (backtrace != NULL, 0);
+  g_return_val_if_fail (thread >= 0 && thread < backtrace->n_threads, 0);
+
+  return backtrace->threads[thread].n_frames;
+}
+
+guintptr
+gimp_backtrace_get_frame_address (GimpBacktrace *backtrace,
+                                  gint           thread,
+                                  gint           frame)
+{
+  g_return_val_if_fail (backtrace != NULL, 0);
+  g_return_val_if_fail (thread >= 0 && thread < backtrace->n_threads, 0);
+
+  frame = gimp_backtrace_normalize_frame (backtrace, thread, frame);
+
+  g_return_val_if_fail (frame >= 0 &&
+                        frame <  backtrace->threads[thread].n_frames, 0);
+
+  return backtrace->threads[thread].frames[frame];
+}
+
+gboolean
+gimp_backtrace_get_address_info (guintptr                  address,
+                                 GimpBacktraceAddressInfo *info)
+{
+  SYMBOL_INFO     *symbol_info;
+  HANDLE           hProcess;
+  HMODULE          hModule;
+  DWORD64          offset      = 0;
+  IMAGEHLP_LINE64  line        = {};
+  DWORD            line_offset = 0;
+  gboolean         result      = FALSE;
+
+  hProcess = GetCurrentProcess ();
+  hModule  = (HMODULE) (guintptr) SymGetModuleBase64 (hProcess, address);
+
+  if (hModule && GetModuleFileNameExA (hProcess, hModule,
+                                       info->object_name,
+                                       sizeof (info->object_name)))
+    {
+      result = TRUE;
+    }
+  else
+    {
+      info->object_name[0] = '\0';
+    }
+
+  symbol_info = g_malloc (sizeof (SYMBOL_INFO)       +
+                          sizeof (info->symbol_name) - 1);
+
+  symbol_info->SizeOfStruct = sizeof (SYMBOL_INFO);
+  symbol_info->MaxNameLen   = sizeof (info->symbol_name);
+
+  if (gimp_backtrace_SymFromAddr (hProcess, address,
+                                  &offset, symbol_info))
+    {
+      g_strlcpy (info->symbol_name, symbol_info->Name,
+                 sizeof (info->symbol_name));
+
+      info->symbol_address = offset ? address - offset : 0;
+
+      result = TRUE;
+    }
+  else
+    {
+      info->symbol_name[0] = '\0';
+      info->symbol_address = 0;
+    }
+
+  g_free (symbol_info);
+
+  if (gimp_backtrace_SymGetLineFromAddr64 (hProcess, address,
+                                           &line_offset, &line))
+    {
+      g_strlcpy (info->source_file, line.FileName,
+                 sizeof (info->source_file));
+
+      info->source_line = line.LineNumber;
+
+      result = TRUE;
+    }
+  else
+    {
+      info->source_file[0] = '\0';
+      info->source_line    = 0;
+    }
+
+  return result;
+}
+
+
+#endif /* GIMP_BACKTRACE_BACKEND_WINDOWS */
diff --git a/app/core/gimpbacktrace.h b/app/core/gimpbacktrace.h
new file mode 100644
index 0000000..8c172b2
--- /dev/null
+++ b/app/core/gimpbacktrace.h
@@ -0,0 +1,70 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpbacktrace.h
+ * Copyright (C) 2018 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_BACKTRACE_H__
+#define __GIMP_BACKTRACE_H__
+
+
+typedef struct _GimpBacktraceAddressInfo GimpBacktraceAddressInfo;
+
+
+struct _GimpBacktraceAddressInfo
+{
+  gchar    object_name[256];
+
+  gchar    symbol_name[256];
+  guintptr symbol_address;
+
+  gchar    source_file[256];
+  gint     source_line;
+};
+
+
+void            gimp_backtrace_init              (void);
+
+gboolean        gimp_backtrace_start             (void);
+void            gimp_backtrace_stop              (void);
+
+GimpBacktrace * gimp_backtrace_new               (gboolean                 include_current_thread);
+void            gimp_backtrace_free              (GimpBacktrace           *backtrace);
+
+gint            gimp_backtrace_get_n_threads     (GimpBacktrace           *backtrace);
+guintptr        gimp_backtrace_get_thread_id     (GimpBacktrace           *backtrace,
+                                                  gint                     thread);
+const gchar   * gimp_backtrace_get_thread_name   (GimpBacktrace           *backtrace,
+                                                  gint                     thread);
+gboolean        gimp_backtrace_is_thread_running (GimpBacktrace           *backtrace,
+                                                  gint                     thread);
+
+gint            gimp_backtrace_find_thread_by_id (GimpBacktrace           *backtrace,
+                                                  guintptr                 thread_id,
+                                                  gint                     thread_hint);
+
+gint            gimp_backtrace_get_n_frames      (GimpBacktrace           *backtrace,
+                                                  gint                     thread);
+guintptr        gimp_backtrace_get_frame_address (GimpBacktrace           *backtrace,
+                                                  gint                     thread,
+                                                  gint                     frame);
+
+gboolean        gimp_backtrace_get_address_info  (guintptr                  address,
+                                                  GimpBacktraceAddressInfo *info);
+
+
+#endif  /*  __GIMP_BACKTRACE_H__  */
diff --git a/app/core/gimpbezierdesc.c b/app/core/gimpbezierdesc.c
new file mode 100644
index 0000000..6047544
--- /dev/null
+++ b/app/core/gimpbezierdesc.c
@@ -0,0 +1,202 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpbezierdesc.c
+ * Copyright (C) 2010 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gegl.h>
+#include <cairo.h>
+
+#include "core-types.h"
+
+#include "gimpbezierdesc.h"
+#include "gimpboundary.h"
+
+
+GType
+gimp_bezier_desc_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    type = g_boxed_type_register_static ("GimpBezierDesc",
+                                         (GBoxedCopyFunc) gimp_bezier_desc_copy,
+                                         (GBoxedFreeFunc) gimp_bezier_desc_free);
+
+  return type;
+}
+
+GimpBezierDesc *
+gimp_bezier_desc_new (cairo_path_data_t *data,
+                      gint               n_data)
+{
+  GimpBezierDesc *desc;
+
+  g_return_val_if_fail (n_data == 0 || data != NULL, NULL);
+
+  desc = g_slice_new (GimpBezierDesc);
+
+  desc->status   = CAIRO_STATUS_SUCCESS;
+  desc->num_data = n_data;
+  desc->data     = data;
+
+  return desc;
+}
+
+static void
+add_polyline (GArray            *path_data,
+              const GimpVector2 *points,
+              gint               n_points,
+              gboolean           closed)
+{
+  GimpVector2       prev = { 0.0, 0.0, };
+  cairo_path_data_t pd;
+  gint              i;
+
+  for (i = 0; i < n_points; i++)
+    {
+      /* compress multiple identical coordinates */
+      if (i == 0 ||
+          prev.x != points[i].x ||
+          prev.y != points[i].y)
+        {
+          pd.header.type   = (i == 0) ? CAIRO_PATH_MOVE_TO : CAIRO_PATH_LINE_TO;
+          pd.header.length = 2;
+
+          g_array_append_val (path_data, pd);
+
+          pd.point.x = points[i].x;
+          pd.point.y = points[i].y;
+
+          g_array_append_val (path_data, pd);
+
+          prev = points[i];
+        }
+    }
+
+  /* close the polyline when needed */
+  if (closed)
+    {
+      pd.header.type   = CAIRO_PATH_CLOSE_PATH;
+      pd.header.length = 1;
+
+      g_array_append_val (path_data, pd);
+    }
+}
+
+GimpBezierDesc *
+gimp_bezier_desc_new_from_bound_segs (GimpBoundSeg *bound_segs,
+                                      gint          n_bound_segs,
+                                      gint          n_bound_groups)
+{
+  GArray      *path_data;
+  GimpVector2 *points;
+  gint         n_points;
+  gint         seg;
+  gint         i;
+  guint        path_data_len;
+
+  g_return_val_if_fail (bound_segs != NULL, NULL);
+  g_return_val_if_fail (n_bound_segs > 0, NULL);
+
+  path_data = g_array_new (FALSE, FALSE, sizeof (cairo_path_data_t));
+
+  points = g_new0 (GimpVector2, n_bound_segs + 4);
+
+  seg = 0;
+  n_points = 0;
+
+  points[n_points].x = (gdouble) (bound_segs[0].x1);
+  points[n_points].y = (gdouble) (bound_segs[0].y1);
+
+  n_points++;
+
+  for (i = 0; i < n_bound_groups; i++)
+    {
+      while (bound_segs[seg].x1 != -1 ||
+             bound_segs[seg].x2 != -1 ||
+             bound_segs[seg].y1 != -1 ||
+             bound_segs[seg].y2 != -1)
+        {
+          points[n_points].x = (gdouble) (bound_segs[seg].x1);
+          points[n_points].y = (gdouble) (bound_segs[seg].y1);
+
+          n_points++;
+          seg++;
+        }
+
+      /* Close the stroke points up */
+      points[n_points] = points[0];
+
+      n_points++;
+
+      add_polyline (path_data, points, n_points, TRUE);
+
+      n_points = 0;
+      seg++;
+
+      points[n_points].x = (gdouble) (bound_segs[seg].x1);
+      points[n_points].y = (gdouble) (bound_segs[seg].y1);
+
+      n_points++;
+    }
+
+  g_free (points);
+
+  path_data_len = path_data->len;
+
+  return gimp_bezier_desc_new ((cairo_path_data_t *) g_array_free (path_data, FALSE),
+                               path_data_len);
+}
+
+void
+gimp_bezier_desc_translate (GimpBezierDesc *desc,
+                            gdouble         offset_x,
+                            gdouble         offset_y)
+{
+  gint i, j;
+
+  g_return_if_fail (desc != NULL);
+
+  for (i = 0; i < desc->num_data; i += desc->data[i].header.length)
+    for (j = 1; j < desc->data[i].header.length; ++j)
+      {
+        desc->data[i+j].point.x += offset_x;
+        desc->data[i+j].point.y += offset_y;
+      }
+}
+
+GimpBezierDesc *
+gimp_bezier_desc_copy (const GimpBezierDesc *desc)
+{
+  g_return_val_if_fail (desc != NULL, NULL);
+
+  return gimp_bezier_desc_new (g_memdup (desc->data,
+                                         desc->num_data * sizeof (cairo_path_data_t)),
+                               desc->num_data);
+}
+
+void
+gimp_bezier_desc_free (GimpBezierDesc *desc)
+{
+  g_return_if_fail (desc != NULL);
+
+  g_free (desc->data);
+  g_slice_free (GimpBezierDesc, desc);
+}
diff --git a/app/core/gimpbezierdesc.h b/app/core/gimpbezierdesc.h
new file mode 100644
index 0000000..3d09dc2
--- /dev/null
+++ b/app/core/gimpbezierdesc.h
@@ -0,0 +1,47 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpbezierdesc.h
+ * Copyright (C) 2010 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_BEZIER_DESC_H__
+#define __GIMP_BEZIER_DESC_H__
+
+
+#define          GIMP_TYPE_BEZIER_DESC     (gimp_bezier_desc_get_type ())
+
+GType            gimp_bezier_desc_get_type (void) G_GNUC_CONST;
+
+
+/* takes ownership of "data" */
+GimpBezierDesc * gimp_bezier_desc_new                 (cairo_path_data_t    *data,
+                                                       gint                  n_data);
+
+/* expects sorted GimpBoundSegs */
+GimpBezierDesc * gimp_bezier_desc_new_from_bound_segs (GimpBoundSeg         *bound_segs,
+                                                       gint                  n_bound_segs,
+                                                       gint                  n_bound_groups);
+
+void             gimp_bezier_desc_translate           (GimpBezierDesc       *desc,
+                                                       gdouble               offset_x,
+                                                       gdouble               offset_y);
+
+GimpBezierDesc * gimp_bezier_desc_copy                (const GimpBezierDesc *desc);
+void             gimp_bezier_desc_free                (GimpBezierDesc       *desc);
+
+
+#endif /* __GIMP_BEZIER_DESC_H__ */
diff --git a/app/core/gimpboundary.c b/app/core/gimpboundary.c
new file mode 100644
index 0000000..995242c
--- /dev/null
+++ b/app/core/gimpboundary.c
@@ -0,0 +1,1016 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+#include <gegl.h>
+
+#include "libgimpmath/gimpmath.h"
+
+#include "core-types.h"
+
+#include "gimpboundary.h"
+
+
+/* GimpBoundSeg array growth parameter */
+#define MAX_SEGS_INC  2048
+
+
+typedef struct _GimpBoundary GimpBoundary;
+
+struct _GimpBoundary
+{
+  /*  The array of segments  */
+  GimpBoundSeg *segs;
+  gint          num_segs;
+  gint          max_segs;
+
+  /*  The array of vertical segments  */
+  gint         *vert_segs;
+
+  /*  The empty segment arrays */
+  gint         *empty_segs_n;
+  gint         *empty_segs_c;
+  gint         *empty_segs_l;
+  gint          max_empty_segs;
+};
+
+
+/*  local function prototypes  */
+
+static GimpBoundary * gimp_boundary_new        (const GeglRectangle *region);
+static GimpBoundSeg * gimp_boundary_free       (GimpBoundary        *boundary,
+                                                gboolean             free_segs);
+
+static void           gimp_boundary_add_seg    (GimpBoundary        *bounrady,
+                                                gint                 x1,
+                                                gint                 y1,
+                                                gint                 x2,
+                                                gint                 y2,
+                                                gboolean             open);
+
+static void           find_empty_segs          (const GeglRectangle *region,
+                                                const gfloat        *line_data,
+                                                gint                 scanline,
+                                                gint                 empty_segs[],
+                                                gint                 max_empty,
+                                                gint                *num_empty,
+                                                GimpBoundaryType     type,
+                                                gint                 x1,
+                                                gint                 y1,
+                                                gint                 x2,
+                                                gint                 y2,
+                                                gfloat               threshold);
+static void           process_horiz_seg        (GimpBoundary        *boundary,
+                                                gint                 x1,
+                                                gint                 y1,
+                                                gint                 x2,
+                                                gint                 y2,
+                                                gboolean             open);
+static void           make_horiz_segs          (GimpBoundary        *boundary,
+                                                gint                 start,
+                                                gint                 end,
+                                                gint                 scanline,
+                                                gint                 empty[],
+                                                gint                 num_empty,
+                                                gint                 top);
+static GimpBoundary * generate_boundary        (GeglBuffer          *buffer,
+                                                const GeglRectangle *region,
+                                                const Babl          *format,
+                                                GimpBoundaryType     type,
+                                                gint                 x1,
+                                                gint                 y1,
+                                                gint                 x2,
+                                                gint                 y2,
+                                                gfloat               threshold);
+
+static gint       cmp_segptr_xy1_addr     (const GimpBoundSeg **seg_ptr_a,
+                                           const GimpBoundSeg **seg_ptr_b);
+static gint       cmp_segptr_xy2_addr     (const GimpBoundSeg **seg_ptr_a,
+                                           const GimpBoundSeg **seg_ptr_b);
+
+static gint       cmp_segptr_xy1          (const GimpBoundSeg **seg_ptr_a,
+                                           const GimpBoundSeg **seg_ptr_b);
+static gint       cmp_segptr_xy2          (const GimpBoundSeg **seg_ptr_a,
+                                           const GimpBoundSeg **seg_ptr_b);
+
+static const GimpBoundSeg * find_segment  (const GimpBoundSeg **segs_by_xy1,
+                                           const GimpBoundSeg **segs_by_xy2,
+                                           gint                 num_segs,
+                                           gint                 x,
+                                           gint                 y);
+
+static const GimpBoundSeg * find_segment_with_func (const GimpBoundSeg **segs,
+                                                    gint                 num_segs,
+                                                    const GimpBoundSeg  *search_seg,
+                                                    GCompareFunc         cmp_func);
+
+static void       simplify_subdivide  (const GimpBoundSeg  *segs,
+                                       gint                 start_idx,
+                                       gint                 end_idx,
+                                       GArray             **ret_points);
+
+
+/*  public functions  */
+
+/**
+ * gimp_boundary_find:
+ * @buffer:    a #GeglBuffer
+ * @format:    a #Babl float format representing the component to analyze
+ * @type:      type of bounds
+ * @x1:        left side of bounds
+ * @y1:        top side of bounds
+ * @x2:        right side of bounds
+ * @y2:        bottom side of bounds
+ * @threshold: pixel value of boundary line
+ * @num_segs:  number of returned #GimpBoundSeg's
+ *
+ * This function returns an array of #GimpBoundSeg's which describe all
+ * outlines along pixel value @threahold, optionally within specified
+ * bounds instead of the whole region.
+ *
+ * The @maskPR parameter can be any PixelRegion.  If the region has
+ * more than 1 bytes/pixel, the last byte of each pixel is used to
+ * determine the boundary outline.
+ *
+ * Return value: the boundary array.
+ **/
+GimpBoundSeg *
+gimp_boundary_find (GeglBuffer          *buffer,
+                    const GeglRectangle *region,
+                    const Babl          *format,
+                    GimpBoundaryType     type,
+                    int                  x1,
+                    int                  y1,
+                    int                  x2,
+                    int                  y2,
+                    gfloat               threshold,
+                    int                 *num_segs)
+{
+  GimpBoundary  *boundary;
+  GeglRectangle  rect = { 0, };
+
+  g_return_val_if_fail (GEGL_IS_BUFFER (buffer), NULL);
+  g_return_val_if_fail (num_segs != NULL, NULL);
+  g_return_val_if_fail (format != NULL, NULL);
+  g_return_val_if_fail (babl_format_get_bytes_per_pixel (format) ==
+                        sizeof (gfloat), NULL);
+
+  if (region)
+    {
+      rect = *region;
+    }
+  else
+    {
+      rect.width  = gegl_buffer_get_width  (buffer);
+      rect.height = gegl_buffer_get_height (buffer);
+    }
+
+  boundary = generate_boundary (buffer, &rect, format, type,
+                                x1, y1, x2, y2, threshold);
+
+  *num_segs = boundary->num_segs;
+
+  return gimp_boundary_free (boundary, FALSE);
+}
+
+/**
+ * gimp_boundary_sort:
+ * @segs:       unsorted input segs.
+ * @num_segs:   number of input segs
+ * @num_groups: number of groups in the sorted segs
+ *
+ * This function takes an array of #GimpBoundSeg's as returned by
+ * gimp_boundary_find() and sorts it by contiguous groups. The returned
+ * array contains markers consisting of -1 coordinates and is
+ * @num_groups elements longer than @segs.
+ *
+ * Return value: the sorted segs
+ **/
+GimpBoundSeg *
+gimp_boundary_sort (const GimpBoundSeg *segs,
+                    gint                num_segs,
+                    gint               *num_groups)
+{
+  GimpBoundary        *boundary;
+  const GimpBoundSeg **segs_ptrs_by_xy1;
+  const GimpBoundSeg **segs_ptrs_by_xy2;
+  gint                 index;
+  gint                 x, y;
+  gint                 startx, starty;
+
+  g_return_val_if_fail ((segs == NULL && num_segs == 0) ||
+                        (segs != NULL && num_segs >  0), NULL);
+  g_return_val_if_fail (num_groups != NULL, NULL);
+
+  *num_groups = 0;
+
+  if (num_segs == 0)
+    return NULL;
+
+  /* prepare arrays with GimpBoundSeg pointers sorted by xy1 and xy2
+   * accordingly
+   */
+  segs_ptrs_by_xy1 = g_new (const GimpBoundSeg *, num_segs);
+  segs_ptrs_by_xy2 = g_new (const GimpBoundSeg *, num_segs);
+
+  for (index = 0; index < num_segs; index++)
+    {
+      segs_ptrs_by_xy1[index] = segs + index;
+      segs_ptrs_by_xy2[index] = segs + index;
+    }
+
+  qsort (segs_ptrs_by_xy1, num_segs, sizeof (GimpBoundSeg *),
+         (GCompareFunc) cmp_segptr_xy1_addr);
+  qsort (segs_ptrs_by_xy2, num_segs, sizeof (GimpBoundSeg *),
+         (GCompareFunc) cmp_segptr_xy2_addr);
+
+  for (index = 0; index < num_segs; index++)
+    ((GimpBoundSeg *) segs)[index].visited = FALSE;
+
+  boundary = gimp_boundary_new (NULL);
+
+  for (index = 0; index < num_segs; index++)
+    {
+      const GimpBoundSeg *cur_seg;
+
+      if (segs[index].visited)
+        continue;
+
+      gimp_boundary_add_seg (boundary,
+                             segs[index].x1, segs[index].y1,
+                             segs[index].x2, segs[index].y2,
+                             segs[index].open);
+
+      ((GimpBoundSeg *) segs)[index].visited = TRUE;
+
+      startx = segs[index].x1;
+      starty = segs[index].y1;
+      x = segs[index].x2;
+      y = segs[index].y2;
+
+      while ((cur_seg = find_segment (segs_ptrs_by_xy1, segs_ptrs_by_xy2,
+                                      num_segs, x, y)) != NULL)
+        {
+          /*  make sure ordering is correct  */
+          if (x == cur_seg->x1 && y == cur_seg->y1)
+            {
+              gimp_boundary_add_seg (boundary,
+                                     cur_seg->x1, cur_seg->y1,
+                                     cur_seg->x2, cur_seg->y2,
+                                     cur_seg->open);
+              x = cur_seg->x2;
+              y = cur_seg->y2;
+            }
+          else
+            {
+              gimp_boundary_add_seg (boundary,
+                                     cur_seg->x2, cur_seg->y2,
+                                     cur_seg->x1, cur_seg->y1,
+                                     cur_seg->open);
+              x = cur_seg->x1;
+              y = cur_seg->y1;
+            }
+
+          ((GimpBoundSeg *) cur_seg)->visited = TRUE;
+        }
+
+      if (G_UNLIKELY (x != startx || y != starty))
+        g_warning ("sort_boundary(): Unconnected boundary group!");
+
+      /*  Mark the end of a group  */
+      *num_groups = *num_groups + 1;
+      gimp_boundary_add_seg (boundary, -1, -1, -1, -1, 0);
+  }
+
+  g_free (segs_ptrs_by_xy1);
+  g_free (segs_ptrs_by_xy2);
+
+  return gimp_boundary_free (boundary, FALSE);
+}
+
+/**
+ * gimp_boundary_simplify:
+ * @sorted_segs: sorted input segs
+ * @num_groups:  number of groups in the sorted segs
+ * @num_segs:    number of returned segs.
+ *
+ * This function takes an array of #GimpBoundSeg's which has been sorted
+ * with gimp_boundary_sort() and reduces the number of segments while
+ * preserving the general shape as close as possible.
+ *
+ * Return value: the simplified segs.
+ **/
+GimpBoundSeg *
+gimp_boundary_simplify (GimpBoundSeg *sorted_segs,
+                        gint          num_groups,
+                        gint         *num_segs)
+{
+  GArray *new_bounds;
+  gint    i, seg;
+
+  g_return_val_if_fail ((sorted_segs == NULL && num_groups == 0) ||
+                        (sorted_segs != NULL && num_groups >  0), NULL);
+  g_return_val_if_fail (num_segs != NULL, NULL);
+
+  new_bounds = g_array_new (FALSE, FALSE, sizeof (GimpBoundSeg));
+
+  seg = 0;
+
+  for (i = 0; i < num_groups; i++)
+    {
+      gint start    = seg;
+      gint n_points = 0;
+
+      while (sorted_segs[seg].x1 != -1 ||
+             sorted_segs[seg].x2 != -1 ||
+             sorted_segs[seg].y1 != -1 ||
+             sorted_segs[seg].y2 != -1)
+        {
+          n_points++;
+          seg++;
+        }
+
+      if (n_points > 0)
+        {
+          GArray   *tmp_points;
+          GimpBoundSeg  tmp_seg;
+          gint      j;
+
+          tmp_points = g_array_new (FALSE, FALSE, sizeof (gint));
+
+          /* temporarily use the delimiter to close the polygon */
+          tmp_seg = sorted_segs[seg];
+          sorted_segs[seg] = sorted_segs[start];
+          simplify_subdivide (sorted_segs,
+                              start, start + n_points, &tmp_points);
+          sorted_segs[seg] = tmp_seg;
+
+          for (j = 0; j < tmp_points->len; j++)
+            g_array_append_val (new_bounds,
+                                sorted_segs[g_array_index (tmp_points,
+                                                           gint, j)]);
+
+          g_array_append_val (new_bounds, sorted_segs[seg]);
+
+          g_array_free (tmp_points, TRUE);
+        }
+
+      seg++;
+    }
+
+  *num_segs = new_bounds->len;
+
+  return (GimpBoundSeg *) g_array_free (new_bounds, FALSE);
+}
+
+void
+gimp_boundary_offset (GimpBoundSeg *segs,
+                      gint          num_segs,
+                      gint          off_x,
+                      gint          off_y)
+{
+  gint i;
+
+  g_return_if_fail ((segs == NULL && num_segs == 0) ||
+                    (segs != NULL && num_segs >  0));
+
+  for (i = 0; i < num_segs; i++)
+    {
+      /* don't offset sorting sentinels */
+      if (!(segs[i].x1 == -1 &&
+            segs[i].y1 == -1 &&
+            segs[i].x2 == -1 &&
+            segs[i].y2 == -1))
+        {
+          segs[i].x1 += off_x;
+          segs[i].y1 += off_y;
+          segs[i].x2 += off_x;
+          segs[i].y2 += off_y;
+        }
+    }
+}
+
+
+/*  private functions  */
+
+static GimpBoundary *
+gimp_boundary_new (const GeglRectangle *region)
+{
+  GimpBoundary *boundary = g_slice_new0 (GimpBoundary);
+
+  if (region)
+    {
+      gint i;
+
+      /*  array for determining the vertical line segments
+       *  which must be drawn
+       */
+      boundary->vert_segs = g_new (gint, region->width + region->x + 1);
+
+      for (i = 0; i <= (region->width + region->x); i++)
+        boundary->vert_segs[i] = -1;
+
+      /*  find the maximum possible number of empty segments
+       *  given the current mask
+       */
+      boundary->max_empty_segs = region->width + 3;
+
+      boundary->empty_segs_n = g_new (gint, boundary->max_empty_segs);
+      boundary->empty_segs_c = g_new (gint, boundary->max_empty_segs);
+      boundary->empty_segs_l = g_new (gint, boundary->max_empty_segs);
+    }
+
+  return boundary;
+}
+
+static GimpBoundSeg *
+gimp_boundary_free (GimpBoundary *boundary,
+                    gboolean      free_segs)
+{
+  GimpBoundSeg *segs = NULL;
+
+  if (free_segs)
+    g_free (boundary->segs);
+  else
+    segs = boundary->segs;
+
+  g_free (boundary->vert_segs);
+  g_free (boundary->empty_segs_n);
+  g_free (boundary->empty_segs_c);
+  g_free (boundary->empty_segs_l);
+
+  g_slice_free (GimpBoundary, boundary);
+
+  return segs;
+}
+
+static void
+gimp_boundary_add_seg (GimpBoundary *boundary,
+                       gint          x1,
+                       gint          y1,
+                       gint          x2,
+                       gint          y2,
+                       gboolean      open)
+{
+  if (boundary->num_segs >= boundary->max_segs)
+    {
+      boundary->max_segs += MAX_SEGS_INC;
+
+      boundary->segs = g_renew (GimpBoundSeg, boundary->segs, boundary->max_segs);
+    }
+
+  boundary->segs[boundary->num_segs].x1   = x1;
+  boundary->segs[boundary->num_segs].y1   = y1;
+  boundary->segs[boundary->num_segs].x2   = x2;
+  boundary->segs[boundary->num_segs].y2   = y2;
+  boundary->segs[boundary->num_segs].open = open;
+
+  boundary->num_segs ++;
+}
+
+static void
+find_empty_segs (const GeglRectangle *region,
+                 const gfloat        *line_data,
+                 gint                 scanline,
+                 gint                 empty_segs[],
+                 gint                 max_empty,
+                 gint                *num_empty,
+                 GimpBoundaryType     type,
+                 gint                 x1,
+                 gint                 y1,
+                 gint                 x2,
+                 gint                 y2,
+                 gfloat               threshold)
+{
+  gint start = 0;
+  gint end   = 0;
+  gint endx  = 0;
+  gint last  = -1;
+  gint l_num_empty;
+  gint x;
+
+  *num_empty = 0;
+
+  if (scanline < region->y || scanline >= (region->y + region->height))
+    {
+      empty_segs[(*num_empty)++] = 0;
+      empty_segs[(*num_empty)++] = G_MAXINT;
+      return;
+    }
+
+  if (type == GIMP_BOUNDARY_WITHIN_BOUNDS)
+    {
+      if (scanline < y1 || scanline >= y2)
+        {
+          empty_segs[(*num_empty)++] = 0;
+          empty_segs[(*num_empty)++] = G_MAXINT;
+          return;
+        }
+
+      start = x1;
+      end   = x2;
+    }
+  else if (type == GIMP_BOUNDARY_IGNORE_BOUNDS)
+    {
+      start = region->x;
+      end   = region->x + region->width;
+      if (scanline < y1 || scanline >= y2)
+        x2 = -1;
+    }
+
+  empty_segs[(*num_empty)++] = 0;
+
+  l_num_empty = *num_empty;
+
+  endx = end;
+
+  line_data += start;
+
+  for (x = start; x < end;)
+    {
+      if (type == GIMP_BOUNDARY_IGNORE_BOUNDS && (endx > x1 || x < x2))
+        {
+          for (; x < endx; x++)
+            {
+              gint val;
+
+              if (*line_data > threshold)
+                {
+                  if (x >= x1 && x < x2)
+                    val = -1;
+                  else
+                    val = 1;
+                }
+              else
+                {
+                  val = -1;
+                }
+
+              line_data++;
+
+              if (last != val)
+                empty_segs[l_num_empty++] = x;
+
+              last = val;
+            }
+        }
+      else
+        {
+          for (; x < endx; x++)
+            {
+              gint val;
+
+              if (*line_data > threshold)
+                val = 1;
+              else
+                val = -1;
+
+              line_data++;
+
+              if (last != val)
+                empty_segs[l_num_empty++] = x;
+
+              last = val;
+            }
+        }
+    }
+
+  *num_empty = l_num_empty;
+
+  if (last > 0)
+    empty_segs[(*num_empty)++] = x;
+
+  empty_segs[(*num_empty)++] = G_MAXINT;
+}
+
+static void
+process_horiz_seg (GimpBoundary *boundary,
+                   gint          x1,
+                   gint          y1,
+                   gint          x2,
+                   gint          y2,
+                   gboolean      open)
+{
+  /*  This procedure accounts for any vertical segments that must be
+      drawn to close in the horizontal segments.                     */
+
+  if (boundary->vert_segs[x1] >= 0)
+    {
+      gimp_boundary_add_seg (boundary, x1, boundary->vert_segs[x1], x1, y1, !open);
+      boundary->vert_segs[x1] = -1;
+    }
+  else
+    boundary->vert_segs[x1] = y1;
+
+  if (boundary->vert_segs[x2] >= 0)
+    {
+      gimp_boundary_add_seg (boundary, x2, boundary->vert_segs[x2], x2, y2, open);
+      boundary->vert_segs[x2] = -1;
+    }
+  else
+    boundary->vert_segs[x2] = y2;
+
+  gimp_boundary_add_seg (boundary, x1, y1, x2, y2, open);
+}
+
+static void
+make_horiz_segs (GimpBoundary *boundary,
+                 gint          start,
+                 gint          end,
+                 gint          scanline,
+                 gint          empty[],
+                 gint          num_empty,
+                 gint          top)
+{
+  gint empty_index;
+  gint e_s, e_e;    /* empty segment start and end values */
+
+  for (empty_index = 0; empty_index < num_empty; empty_index += 2)
+    {
+      e_s = *empty++;
+      e_e = *empty++;
+
+      if (e_s <= start && e_e >= end)
+        {
+          process_horiz_seg (boundary,
+                             start, scanline, end, scanline, top);
+        }
+      else if ((e_s > start && e_s < end) ||
+               (e_e < end && e_e > start))
+        {
+          process_horiz_seg (boundary,
+                             MAX (e_s, start), scanline,
+                             MIN (e_e, end), scanline, top);
+        }
+    }
+}
+
+static GimpBoundary *
+generate_boundary (GeglBuffer          *buffer,
+                   const GeglRectangle *region,
+                   const Babl          *format,
+                   GimpBoundaryType     type,
+                   gint                 x1,
+                   gint                 y1,
+                   gint                 x2,
+                   gint                 y2,
+                   gfloat               threshold)
+{
+  GimpBoundary  *boundary;
+  GeglRectangle  line_rect = { 0, };
+  gfloat        *line_data;
+  gint           scanline;
+  gint           i;
+  gint           start, end;
+  gint          *tmp_segs;
+
+  gint          num_empty_n = 0;
+  gint          num_empty_c = 0;
+  gint          num_empty_l = 0;
+
+  boundary = gimp_boundary_new (region);
+
+  line_rect.width  = gegl_buffer_get_width (buffer);
+  line_rect.height = 1;
+
+  line_data = g_alloca (sizeof (gfloat) * line_rect.width);
+
+  start = 0;
+  end   = 0;
+
+  if (type == GIMP_BOUNDARY_WITHIN_BOUNDS)
+    {
+      start = y1;
+      end   = y2;
+    }
+  else if (type == GIMP_BOUNDARY_IGNORE_BOUNDS)
+    {
+      start = region->y;
+      end   = region->y + region->height;
+    }
+
+  /*  Find the empty segments for the previous and current scanlines  */
+  find_empty_segs (region, NULL,
+                   start - 1, boundary->empty_segs_l,
+                   boundary->max_empty_segs, &num_empty_l,
+                   type, x1, y1, x2, y2,
+                   threshold);
+
+  line_rect.y = start;
+  gegl_buffer_get (buffer, &line_rect, 1.0, format,
+                   line_data, GEGL_AUTO_ROWSTRIDE,
+                   GEGL_ABYSS_NONE);
+
+  find_empty_segs (region, line_data,
+                   start, boundary->empty_segs_c,
+                   boundary->max_empty_segs, &num_empty_c,
+                   type, x1, y1, x2, y2,
+                   threshold);
+
+  for (scanline = start; scanline < end; scanline++)
+    {
+      /*  find the empty segment list for the next scanline  */
+      line_rect.y = scanline + 1;
+      if (scanline + 1 == end)
+        line_data = NULL;
+      else
+        gegl_buffer_get (buffer, &line_rect, 1.0, format,
+                         line_data, GEGL_AUTO_ROWSTRIDE,
+                         GEGL_ABYSS_NONE);
+
+      find_empty_segs (region, line_data,
+                       scanline + 1, boundary->empty_segs_n,
+                       boundary->max_empty_segs, &num_empty_n,
+                       type, x1, y1, x2, y2,
+                       threshold);
+
+      /*  process the segments on the current scanline  */
+      for (i = 1; i < num_empty_c - 1; i += 2)
+        {
+          make_horiz_segs (boundary,
+                           boundary->empty_segs_c [i],
+                           boundary->empty_segs_c [i+1],
+                           scanline,
+                           boundary->empty_segs_l, num_empty_l, 1);
+          make_horiz_segs (boundary,
+                           boundary->empty_segs_c [i],
+                           boundary->empty_segs_c [i+1],
+                           scanline + 1,
+                           boundary->empty_segs_n, num_empty_n, 0);
+        }
+
+      /*  get the next scanline of empty segments, swap others  */
+      tmp_segs               = boundary->empty_segs_l;
+      boundary->empty_segs_l = boundary->empty_segs_c;
+      num_empty_l            = num_empty_c;
+      boundary->empty_segs_c = boundary->empty_segs_n;
+      num_empty_c            = num_empty_n;
+      boundary->empty_segs_n = tmp_segs;
+    }
+
+  return boundary;
+}
+
+/*  sorting utility functions  */
+
+static inline gint
+cmp_xy (const gint ax,
+        const gint ay,
+        const gint bx,
+        const gint by)
+{
+  if (ay < by)
+    {
+      return -1;
+    }
+  else if (ay > by)
+    {
+      return 1;
+    }
+  else if (ax < bx)
+    {
+      return -1;
+    }
+  else if (ax > bx)
+    {
+      return 1;
+    }
+  else
+    {
+      return 0;
+    }
+}
+
+
+/*
+ * Compares (x1, y1) pairs in specified segments, using their addresses if
+ * (x1, y1) pairs are equal.
+ */
+static gint
+cmp_segptr_xy1_addr (const GimpBoundSeg **seg_ptr_a,
+                     const GimpBoundSeg **seg_ptr_b)
+{
+  const GimpBoundSeg *seg_a = *seg_ptr_a;
+  const GimpBoundSeg *seg_b = *seg_ptr_b;
+
+  gint result = cmp_xy (seg_a->x1, seg_a->y1, seg_b->x1, seg_b->y1);
+
+  if (result == 0)
+    {
+      if (seg_a < seg_b)
+        result = -1;
+      else if (seg_a > seg_b)
+        result = 1;
+    }
+
+  return result;
+}
+
+/*
+ * Compares (x2, y2) pairs in specified segments, using their addresses if
+ * (x2, y2) pairs are equal.
+ */
+static gint
+cmp_segptr_xy2_addr (const GimpBoundSeg **seg_ptr_a,
+                     const GimpBoundSeg **seg_ptr_b)
+{
+  const GimpBoundSeg *seg_a = *seg_ptr_a;
+  const GimpBoundSeg *seg_b = *seg_ptr_b;
+
+  gint result = cmp_xy (seg_a->x2, seg_a->y2, seg_b->x2, seg_b->y2);
+
+  if (result == 0)
+    {
+      if (seg_a < seg_b)
+        result = -1;
+      else if (seg_a > seg_b)
+        result = 1;
+    }
+
+  return result;
+}
+
+
+/*
+ * Compares (x1, y1) pairs in specified segments.
+ */
+static gint
+cmp_segptr_xy1 (const GimpBoundSeg **seg_ptr_a,
+                const GimpBoundSeg **seg_ptr_b)
+{
+  const GimpBoundSeg *seg_a = *seg_ptr_a, *seg_b = *seg_ptr_b;
+
+  return cmp_xy (seg_a->x1, seg_a->y1, seg_b->x1, seg_b->y1);
+}
+
+/*
+ * Compares (x2, y2) pairs in specified segments.
+ */
+static gint
+cmp_segptr_xy2 (const GimpBoundSeg **seg_ptr_a,
+                const GimpBoundSeg **seg_ptr_b)
+{
+  const GimpBoundSeg *seg_a = *seg_ptr_a;
+  const GimpBoundSeg *seg_b = *seg_ptr_b;
+
+  return cmp_xy (seg_a->x2, seg_a->y2, seg_b->x2, seg_b->y2);
+}
+
+
+static const GimpBoundSeg *
+find_segment (const GimpBoundSeg **segs_by_xy1,
+              const GimpBoundSeg **segs_by_xy2,
+              gint                 num_segs,
+              gint                 x,
+              gint                 y)
+{
+  const GimpBoundSeg *segptr_xy1;
+  const GimpBoundSeg *segptr_xy2;
+  GimpBoundSeg        search_seg;
+
+  search_seg.x1 = search_seg.x2 = x;
+  search_seg.y1 = search_seg.y2 = y;
+
+  segptr_xy1 = find_segment_with_func (segs_by_xy1, num_segs, &search_seg,
+                                       (GCompareFunc) cmp_segptr_xy1);
+  segptr_xy2 = find_segment_with_func (segs_by_xy2, num_segs, &search_seg,
+                                       (GCompareFunc) cmp_segptr_xy2);
+
+  /* return segment with smaller address */
+  if (segptr_xy1 != NULL && segptr_xy2 != NULL)
+    return MIN(segptr_xy1, segptr_xy2);
+  else if (segptr_xy1 != NULL)
+    return segptr_xy1;
+  else if (segptr_xy2 != NULL)
+    return segptr_xy2;
+
+  return NULL;
+}
+
+
+static const GimpBoundSeg *
+find_segment_with_func (const GimpBoundSeg **segs,
+                        gint                 num_segs,
+                        const GimpBoundSeg  *search_seg,
+                        GCompareFunc         cmp_func)
+{
+  const GimpBoundSeg **seg;
+  const GimpBoundSeg *found_seg = NULL;
+
+  seg = bsearch (&search_seg, segs, num_segs, sizeof (GimpBoundSeg *), cmp_func);
+
+  if (seg != NULL)
+    {
+      /* find first matching segment */
+      while (seg > segs && cmp_func (seg - 1, &search_seg) == 0)
+        seg--;
+
+      /* find first non-visited segment */
+      while (seg != segs + num_segs && cmp_func (seg, &search_seg) == 0)
+        if (!(*seg)->visited)
+          {
+            found_seg = *seg;
+            break;
+          }
+        else
+          seg++;
+    }
+
+    return found_seg;
+}
+
+
+/*  simplifying utility functions  */
+
+static void
+simplify_subdivide (const GimpBoundSeg *segs,
+                    gint                start_idx,
+                    gint                end_idx,
+                    GArray            **ret_points)
+{
+  gint maxdist_idx;
+  gint maxdist;
+  gint threshold;
+  gint i, dx, dy;
+
+  if (end_idx - start_idx < 2)
+    {
+      *ret_points = g_array_append_val (*ret_points, start_idx);
+      return;
+    }
+
+  maxdist = 0;
+
+  if (segs[start_idx].x1 == segs[end_idx].x1 &&
+      segs[start_idx].y1 == segs[end_idx].y1)
+    {
+      /* start and endpoint are at the same coordinates */
+      for (i = start_idx + 1; i < end_idx; i++)
+        {
+          /* compare the sqared distances */
+          gint dist = (SQR (segs[i].x1 - segs[start_idx].x1) +
+                       SQR (segs[i].y1 - segs[start_idx].y1));
+
+          if (dist > maxdist)
+            {
+              maxdist = dist;
+            }
+        }
+
+      threshold = 1;
+    }
+  else
+    {
+      dx = segs[end_idx].x1 - segs[start_idx].x1;
+      dy = segs[end_idx].y1 - segs[start_idx].y1;
+
+      for (i = start_idx + 1; i < end_idx; i++)
+        {
+          /* this is not really the euclidic distance, but is
+           * proportional for this part of the line
+           * (for the real distance we'd have to divide by
+           * (SQR(dx)+SQR(dy)))
+           */
+          gint dist = abs (dx * (segs[start_idx].y1 - segs[i].y1) -
+                           dy * (segs[start_idx].x1 - segs[i].x1));
+
+          if (dist > maxdist)
+            {
+              maxdist = dist;
+            }
+        }
+
+      /* threshold is chosen to catch 45 degree stairs */
+      threshold = SQR (dx) + SQR (dy);
+    }
+
+  if (maxdist <= threshold)
+    {
+      *ret_points = g_array_append_val (*ret_points, start_idx);
+      return;
+    }
+
+  /* Simons hack */
+  maxdist_idx = (start_idx + end_idx) / 2;
+
+  simplify_subdivide (segs, start_idx, maxdist_idx, ret_points);
+  simplify_subdivide (segs, maxdist_idx, end_idx, ret_points);
+}
diff --git a/app/core/gimpboundary.h b/app/core/gimpboundary.h
new file mode 100644
index 0000000..1e05eec
--- /dev/null
+++ b/app/core/gimpboundary.h
@@ -0,0 +1,68 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef  __GIMP_BOUNDARY_H__
+#define  __GIMP_BOUNDARY_H__
+
+
+/* half intensity for mask */
+#define GIMP_BOUNDARY_HALF_WAY 0.5
+
+
+typedef enum
+{
+  GIMP_BOUNDARY_WITHIN_BOUNDS,
+  GIMP_BOUNDARY_IGNORE_BOUNDS
+} GimpBoundaryType;
+
+
+struct _GimpBoundSeg
+{
+  gint   x1;
+  gint   y1;
+  gint   x2;
+  gint   y2;
+  guint  open    : 1;
+  guint  visited : 1;
+};
+
+
+GimpBoundSeg * gimp_boundary_find      (GeglBuffer          *buffer,
+                                        const GeglRectangle *region,
+                                        const Babl          *format,
+                                        GimpBoundaryType     type,
+                                        gint                 x1,
+                                        gint                 y1,
+                                        gint                 x2,
+                                        gint                 y2,
+                                        gfloat               threshold,
+                                        gint                *num_segs);
+GimpBoundSeg * gimp_boundary_sort      (const GimpBoundSeg  *segs,
+                                        gint                 num_segs,
+                                        gint                *num_groups);
+GimpBoundSeg * gimp_boundary_simplify  (GimpBoundSeg        *sorted_segs,
+                                        gint                 num_groups,
+                                        gint                *num_segs);
+
+/* offsets in-place */
+void       gimp_boundary_offset        (GimpBoundSeg        *segs,
+                                        gint                 num_segs,
+                                        gint                 off_x,
+                                        gint                 off_y);
+
+
+#endif  /*  __GIMP_BOUNDARY_H__  */
diff --git a/app/core/gimpbrush-boundary.c b/app/core/gimpbrush-boundary.c
new file mode 100644
index 0000000..9e5cbaa
--- /dev/null
+++ b/app/core/gimpbrush-boundary.c
@@ -0,0 +1,130 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <cairo.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gimpbezierdesc.h"
+#include "gimpboundary.h"
+#include "gimpbrush.h"
+#include "gimpbrush-boundary.h"
+#include "gimptempbuf.h"
+
+
+static GimpBezierDesc *
+gimp_brush_transform_boundary_exact (GimpBrush *brush,
+                                     gdouble    scale,
+                                     gdouble    aspect_ratio,
+                                     gdouble    angle,
+                                     gboolean   reflect,
+                                     gdouble    hardness)
+{
+  const GimpTempBuf *mask;
+
+  mask = gimp_brush_transform_mask (brush,
+                                    scale, aspect_ratio,
+                                    angle, reflect, hardness);
+
+  if (mask)
+    {
+      GeglBuffer    *buffer;
+      GimpBoundSeg  *bound_segs;
+      gint           n_bound_segs;
+
+      buffer = gimp_temp_buf_create_buffer ((GimpTempBuf *) mask);
+
+      bound_segs = gimp_boundary_find (buffer, NULL,
+                                       babl_format ("Y float"),
+                                       GIMP_BOUNDARY_WITHIN_BOUNDS,
+                                       0, 0,
+                                       gegl_buffer_get_width  (buffer),
+                                       gegl_buffer_get_height (buffer),
+                                       0.0,
+                                       &n_bound_segs);
+
+      g_object_unref (buffer);
+
+      if (bound_segs)
+        {
+          GimpBoundSeg *stroke_segs;
+          gint          n_stroke_groups;
+
+          stroke_segs = gimp_boundary_sort (bound_segs, n_bound_segs,
+                                            &n_stroke_groups);
+
+          g_free (bound_segs);
+
+          if (stroke_segs)
+            {
+              GimpBezierDesc *path;
+
+              path = gimp_bezier_desc_new_from_bound_segs (stroke_segs,
+                                                           n_bound_segs,
+                                                           n_stroke_groups);
+
+              g_free (stroke_segs);
+
+              return path;
+            }
+        }
+    }
+
+  return NULL;
+}
+
+static GimpBezierDesc *
+gimp_brush_transform_boundary_approx (GimpBrush *brush,
+                                      gdouble    scale,
+                                      gdouble    aspect_ratio,
+                                      gdouble    angle,
+                                      gboolean   reflect,
+                                      gdouble    hardness)
+{
+  return gimp_brush_transform_boundary_exact (brush,
+                                              scale, aspect_ratio,
+                                              angle, reflect, hardness);
+}
+
+GimpBezierDesc *
+gimp_brush_real_transform_boundary (GimpBrush *brush,
+                                    gdouble    scale,
+                                    gdouble    aspect_ratio,
+                                    gdouble    angle,
+                                    gboolean   reflect,
+                                    gdouble    hardness,
+                                    gint      *width,
+                                    gint      *height)
+{
+  gimp_brush_transform_size (brush, scale, aspect_ratio, angle, reflect,
+                             width, height);
+
+  if (*width < 256 && *height < 256)
+    {
+      return gimp_brush_transform_boundary_exact (brush,
+                                                  scale, aspect_ratio,
+                                                  angle, reflect, hardness);
+    }
+
+  return gimp_brush_transform_boundary_approx (brush,
+                                               scale, aspect_ratio,
+                                               angle, reflect, hardness);
+}
diff --git a/app/core/gimpbrush-boundary.h b/app/core/gimpbrush-boundary.h
new file mode 100644
index 0000000..0bc99db
--- /dev/null
+++ b/app/core/gimpbrush-boundary.h
@@ -0,0 +1,32 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_BRUSH_BOUNDARY_H__
+#define __GIMP_BRUSH_BOUNDARY_H__
+
+
+GimpBezierDesc * gimp_brush_real_transform_boundary (GimpBrush *brush,
+                                                     gdouble    scale,
+                                                     gdouble    aspect_ratio,
+                                                     gdouble    angle,
+                                                     gboolean   reflect,
+                                                     gdouble    hardness,
+                                                     gint      *width,
+                                                     gint      *height);
+
+
+#endif /* __GIMP_BRUSH_BOUNDARY_H__ */
diff --git a/app/core/gimpbrush-header.h b/app/core/gimpbrush-header.h
new file mode 100644
index 0000000..0e66715
--- /dev/null
+++ b/app/core/gimpbrush-header.h
@@ -0,0 +1,49 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_BRUSH_HEADER_H__
+#define __GIMP_BRUSH_HEADER_H__
+
+
+#define GIMP_BRUSH_MAGIC    (('G' << 24) + ('I' << 16) + \
+                             ('M' << 8)  + ('P' << 0))
+#define GIMP_BRUSH_MAX_SIZE 10000 /* Max size in either dimension in px */
+#define GIMP_BRUSH_MAX_NAME 256   /* Max length of the brush's name     */
+
+
+/*  All field entries are MSB  */
+
+typedef struct _GimpBrushHeader GimpBrushHeader;
+
+struct _GimpBrushHeader
+{
+  guint32   header_size;  /*  = sizeof (GimpBrushHeader) + brush name  */
+  guint32   version;      /*  brush file version #  */
+  guint32   width;        /*  width of brush  */
+  guint32   height;       /*  height of brush  */
+  guint32   bytes;        /*  depth of brush in bytes  */
+  guint32   magic_number; /*  GIMP brush magic number  */
+  guint32   spacing;      /*  brush spacing  */
+};
+
+/*  In a brush file, next comes the brush name, null-terminated.
+ *  After that comes the brush data -- width * height * bytes bytes of
+ *  it...
+ */
+
+
+#endif /* __GIMP_BRUSH_HEADER_H__ */
diff --git a/app/core/gimpbrush-load.c b/app/core/gimpbrush-load.c
new file mode 100644
index 0000000..51bf1da
--- /dev/null
+++ b/app/core/gimpbrush-load.c
@@ -0,0 +1,1213 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpbrush-load.c
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+
+#include "core-types.h"
+
+#include "gimpbrush.h"
+#include "gimpbrush-header.h"
+#include "gimpbrush-load.h"
+#include "gimpbrush-private.h"
+#include "gimppattern-header.h"
+#include "gimptempbuf.h"
+
+#include "gimp-intl.h"
+
+/* stuff from abr2gbr Copyright (C) 2001 Marco Lamberto <lm@sunnyspot.org>  */
+/* the above is GPL  see http://the.sunnyspot.org/gimp/  */
+
+typedef struct _AbrHeader               AbrHeader;
+typedef struct _AbrBrushHeader          AbrBrushHeader;
+typedef struct _AbrSampledBrushHeader   AbrSampledBrushHeader;
+
+struct _AbrHeader
+{
+  gint16 version;
+  gint16 count;
+};
+
+struct _AbrBrushHeader
+{
+  gint16 type;
+  gint32 size;
+};
+
+struct _AbrSampledBrushHeader
+{
+  gint32   misc;
+  gint16   spacing;
+  gchar    antialiasing;
+  gint16   bounds[4];
+  gint32   bounds_long[4];
+  gint16   depth;
+  gboolean wide;
+};
+
+
+/*  local function prototypes  */
+
+static GList     * gimp_brush_load_abr_v12       (GDataInputStream  *input,
+                                                  AbrHeader         *abr_hdr,
+                                                  GFile             *file,
+                                                  GError           **error);
+static GList     * gimp_brush_load_abr_v6        (GDataInputStream  *input,
+                                                  AbrHeader         *abr_hdr,
+                                                  GFile             *file,
+                                                  GError           **error);
+static GimpBrush * gimp_brush_load_abr_brush_v12 (GDataInputStream  *input,
+                                                  AbrHeader         *abr_hdr,
+                                                  gint               index,
+                                                  GFile             *file,
+                                                  GError           **error);
+static GimpBrush * gimp_brush_load_abr_brush_v6  (GDataInputStream  *input,
+                                                  AbrHeader         *abr_hdr,
+                                                  gint32             max_offset,
+                                                  gint               index,
+                                                  GFile             *file,
+                                                  GError           **error);
+
+static gchar       abr_read_char                 (GDataInputStream  *input,
+                                                  GError           **error);
+static gint16      abr_read_short                (GDataInputStream  *input,
+                                                  GError           **error);
+static gint32      abr_read_long                 (GDataInputStream  *input,
+                                                  GError           **error);
+static gchar     * abr_read_ucs2_text            (GDataInputStream  *input,
+                                                  GError           **error);
+static gboolean    abr_supported                 (AbrHeader         *abr_hdr,
+                                                  GError           **error);
+static gboolean    abr_reach_8bim_section        (GDataInputStream  *input,
+                                                  const gchar       *name,
+                                                  GError           **error);
+static gboolean    abr_rle_decode                (GDataInputStream  *input,
+                                                  gchar             *buffer,
+                                                  gsize              buffer_size,
+                                                  gint32             height,
+                                                  GError           **error);
+
+
+/*  public functions  */
+
+GList *
+gimp_brush_load (GimpContext   *context,
+                 GFile         *file,
+                 GInputStream  *input,
+                 GError       **error)
+{
+  GimpBrush *brush;
+
+  g_return_val_if_fail (G_IS_FILE (file), NULL);
+  g_return_val_if_fail (G_IS_INPUT_STREAM (input), NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, NULL);
+
+  brush = gimp_brush_load_brush (context, file, input, error);
+  if (! brush)
+    return NULL;
+
+  return g_list_prepend (NULL, brush);
+}
+
+GimpBrush *
+gimp_brush_load_brush (GimpContext   *context,
+                       GFile         *file,
+                       GInputStream  *input,
+                       GError       **error)
+{
+  GimpBrush       *brush;
+  gsize            bn_size;
+  GimpBrushHeader  header;
+  gchar           *name = NULL;
+  guchar          *mask;
+  gsize            bytes_read;
+  gssize           i, size;
+  gboolean         success = TRUE;
+
+  g_return_val_if_fail (G_IS_FILE (file), NULL);
+  g_return_val_if_fail (G_IS_INPUT_STREAM (input), NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, NULL);
+
+  /*  read the header  */
+  if (! g_input_stream_read_all (input, &header, sizeof (header),
+                                 &bytes_read, NULL, error) ||
+      bytes_read != sizeof (header))
+    {
+      return NULL;
+    }
+
+  /*  rearrange the bytes in each unsigned int  */
+  header.header_size  = g_ntohl (header.header_size);
+  header.version      = g_ntohl (header.version);
+  header.width        = g_ntohl (header.width);
+  header.height       = g_ntohl (header.height);
+  header.bytes        = g_ntohl (header.bytes);
+  header.magic_number = g_ntohl (header.magic_number);
+  header.spacing      = g_ntohl (header.spacing);
+
+  /*  Check for correct file format */
+
+  if (header.width == 0)
+    {
+      g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                   _("Fatal parse error in brush file: Width = 0."));
+      return NULL;
+    }
+
+  if (header.height == 0)
+    {
+      g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                   _("Fatal parse error in brush file: Height = 0."));
+      return NULL;
+    }
+
+  if (header.bytes == 0)
+    {
+      g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                   _("Fatal parse error in brush file: Bytes = 0."));
+      return NULL;
+    }
+
+  if (header.width  > GIMP_BRUSH_MAX_SIZE ||
+      header.height > GIMP_BRUSH_MAX_SIZE ||
+      G_MAXSIZE / header.width / header.height / MAX (4, header.bytes) < 1)
+    {
+      g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                   _("Fatal parse error in brush file: %dx%d over max size."),
+                   header.width, header.height);
+      return NULL;
+    }
+
+  switch (header.version)
+    {
+    case 1:
+      /*  If this is a version 1 brush, set the fp back 8 bytes  */
+      if (! g_seekable_seek (G_SEEKABLE (input), -8, G_SEEK_CUR,
+                             NULL, error))
+        return NULL;
+
+      header.header_size += 8;
+      /*  spacing is not defined in version 1  */
+      header.spacing = 25;
+      break;
+
+    case 3:  /*  cinepaint brush  */
+      if (header.bytes == 18  /* FLOAT16_GRAY_GIMAGE */)
+        {
+          header.bytes = 2;
+        }
+      else
+        {
+          g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                       _("Fatal parse error in brush file: Unknown depth %d."),
+                       header.bytes);
+          return NULL;
+        }
+      /*  fallthrough  */
+
+    case 2:
+      if (header.magic_number == GIMP_BRUSH_MAGIC)
+        break;
+
+    default:
+      g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                   _("Fatal parse error in brush file: Unknown version %d."),
+                   header.version);
+      return NULL;
+    }
+
+  if (header.header_size < sizeof (GimpBrushHeader))
+    {
+      g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                   _("Unsupported brush format"));
+      return NULL;
+    }
+
+  /*  Read in the brush name  */
+  if ((bn_size = (header.header_size - sizeof (header))))
+    {
+      gchar *utf8;
+
+      if (bn_size > GIMP_BRUSH_MAX_NAME)
+        {
+          g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                       _("Invalid header data in '%s': "
+                         "Brush name is too long: %lu"),
+                       gimp_file_get_utf8_name (file),
+                       (gulong) bn_size);
+          return NULL;
+        }
+
+      name = g_new0 (gchar, bn_size + 1);
+
+      if (! g_input_stream_read_all (input, name, bn_size,
+                                     &bytes_read, NULL, error) ||
+          bytes_read != bn_size)
+        {
+          g_free (name);
+          return NULL;
+        }
+
+      utf8 = gimp_any_to_utf8 (name, bn_size - 1,
+                               _("Invalid UTF-8 string in brush file '%s'."),
+                               gimp_file_get_utf8_name (file));
+      g_free (name);
+      name = utf8;
+    }
+
+  if (! name)
+    name = g_strdup (_("Unnamed"));
+
+  brush = g_object_new (GIMP_TYPE_BRUSH,
+                        "name",      name,
+                        "mime-type", "image/x-gimp-gbr",
+                        NULL);
+  g_free (name);
+
+  brush->priv->mask = gimp_temp_buf_new (header.width, header.height,
+                                         babl_format ("Y u8"));
+
+  mask = gimp_temp_buf_get_data (brush->priv->mask);
+  size = header.width * header.height * header.bytes;
+
+  switch (header.bytes)
+    {
+    case 1:
+      success = (g_input_stream_read_all (input, mask, size,
+                                          &bytes_read, NULL, error) &&
+                 bytes_read == size);
+
+      /* For backwards-compatibility, check if a pattern follows.
+       * The obsolete .gpb format did it this way.
+       */
+      if (success)
+        {
+          GimpPatternHeader ph;
+          goffset           rewind;
+
+          rewind = g_seekable_tell (G_SEEKABLE (input));
+
+          if (g_input_stream_read_all (input, &ph, sizeof (GimpPatternHeader),
+                                       &bytes_read, NULL, NULL) &&
+              bytes_read == sizeof (GimpPatternHeader))
+            {
+              /*  rearrange the bytes in each unsigned int  */
+              ph.header_size  = g_ntohl (ph.header_size);
+              ph.version      = g_ntohl (ph.version);
+              ph.width        = g_ntohl (ph.width);
+              ph.height       = g_ntohl (ph.height);
+              ph.bytes        = g_ntohl (ph.bytes);
+              ph.magic_number = g_ntohl (ph.magic_number);
+
+              if (ph.magic_number == GIMP_PATTERN_MAGIC        &&
+                  ph.version      == 1                         &&
+                  ph.header_size  > sizeof (GimpPatternHeader) &&
+                  ph.bytes        == 3                         &&
+                  ph.width        == header.width              &&
+                  ph.height       == header.height             &&
+                  g_input_stream_skip (input,
+                                       ph.header_size -
+                                       sizeof (GimpPatternHeader),
+                                       NULL, NULL) ==
+                  ph.header_size - sizeof (GimpPatternHeader))
+                {
+                  guchar *pixmap;
+                  gssize  pixmap_size;
+
+                  brush->priv->pixmap =
+                    gimp_temp_buf_new (header.width, header.height,
+                                       babl_format ("R'G'B' u8"));
+
+                  pixmap = gimp_temp_buf_get_data (brush->priv->pixmap);
+
+                  pixmap_size = gimp_temp_buf_get_data_size (brush->priv->pixmap);
+
+                  success = (g_input_stream_read_all (input, pixmap,
+                                                      pixmap_size,
+                                                      &bytes_read, NULL,
+                                                      error) &&
+                             bytes_read == pixmap_size);
+                }
+              else
+                {
+                  /*  seek back if pattern wasn't found  */
+                  success = g_seekable_seek (G_SEEKABLE (input),
+                                             rewind, G_SEEK_SET,
+                                             NULL, error);
+                }
+            }
+        }
+      break;
+
+    case 2:  /*  cinepaint brush, 16 bit floats  */
+      {
+        guchar buf[8 * 1024];
+
+        for (i = 0; success && i < size;)
+          {
+            gssize bytes = MIN (size - i, sizeof (buf));
+
+            success = (g_input_stream_read_all (input, buf, bytes,
+                                                &bytes_read, NULL, error) &&
+                       bytes_read == bytes);
+
+            if (success)
+              {
+                guint16 *b = (guint16 *) buf;
+
+                i += bytes;
+
+                for (; bytes > 0; bytes -= 2, mask++, b++)
+                  {
+                    union
+                    {
+                      guint16 u[2];
+                      gfloat  f;
+                    } short_float;
+
+#if G_BYTE_ORDER == G_LITTLE_ENDIAN
+                    short_float.u[0] = 0;
+                    short_float.u[1] = GUINT16_FROM_BE (*b);
+#else
+                    short_float.u[0] = GUINT16_FROM_BE (*b);
+                    short_float.u[1] = 0;
+#endif
+
+                    *mask = (guchar) (short_float.f * 255.0 + 0.5);
+                  }
+              }
+          }
+      }
+      break;
+
+    case 4:
+      {
+        guchar *pixmap;
+        guchar  buf[8 * 1024];
+
+        brush->priv->pixmap = gimp_temp_buf_new (header.width, header.height,
+                                                 babl_format ("R'G'B' u8"));
+        pixmap = gimp_temp_buf_get_data (brush->priv->pixmap);
+
+        for (i = 0; success && i < size;)
+          {
+            gssize bytes = MIN (size - i, sizeof (buf));
+
+            success = (g_input_stream_read_all (input, buf, bytes,
+                                                &bytes_read, NULL, error) &&
+                       bytes_read == bytes);
+
+            if (success)
+              {
+                guchar *b = buf;
+
+                i += bytes;
+
+                for (; bytes > 0; bytes -= 4, pixmap += 3, mask++, b += 4)
+                  {
+                    pixmap[0] = b[0];
+                    pixmap[1] = b[1];
+                    pixmap[2] = b[2];
+
+                    mask[0]   = b[3];
+                  }
+              }
+          }
+      }
+      break;
+
+    default:
+      g_object_unref (brush);
+      g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                   _("Fatal parse error in brush file:\n"
+                     "Unsupported brush depth %d\n"
+                     "GIMP brushes must be GRAY or RGBA."),
+                   header.bytes);
+      return NULL;
+    }
+
+  if (! success)
+    {
+      g_object_unref (brush);
+      return NULL;
+    }
+
+  brush->priv->spacing  = header.spacing;
+  brush->priv->x_axis.x = header.width  / 2.0;
+  brush->priv->x_axis.y = 0.0;
+  brush->priv->y_axis.x = 0.0;
+  brush->priv->y_axis.y = header.height / 2.0;
+
+  return brush;
+}
+
+GList *
+gimp_brush_load_abr (GimpContext   *context,
+                     GFile         *file,
+                     GInputStream  *input,
+                     GError       **error)
+{
+  GDataInputStream *data_input;
+  AbrHeader         abr_hdr;
+  GList            *brush_list = NULL;
+  GError           *my_error   = NULL;
+
+  g_return_val_if_fail (G_IS_FILE (file), NULL);
+  g_return_val_if_fail (G_IS_INPUT_STREAM (input), NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, NULL);
+
+  data_input = g_data_input_stream_new (input);
+
+  g_data_input_stream_set_byte_order (data_input,
+                                      G_DATA_STREAM_BYTE_ORDER_BIG_ENDIAN);
+
+  abr_hdr.version = abr_read_short (data_input, &my_error);
+  if (my_error)
+    goto done;
+
+  /* sub-version for ABR v6 */
+  abr_hdr.count = abr_read_short (data_input, &my_error);
+  if (my_error)
+    goto done;
+
+  if (abr_supported (&abr_hdr, &my_error))
+    {
+      switch (abr_hdr.version)
+        {
+        case 1:
+        case 2:
+          brush_list = gimp_brush_load_abr_v12 (data_input, &abr_hdr,
+                                                file, &my_error);
+          break;
+
+        case 10:
+        case 6:
+          brush_list = gimp_brush_load_abr_v6 (data_input, &abr_hdr,
+                                               file, &my_error);
+          break;
+        }
+    }
+
+ done:
+
+  g_object_unref (data_input);
+
+  if (! brush_list)
+    {
+      if (! my_error)
+        g_set_error (&my_error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                     _("Unable to decode abr format version %d."),
+                     abr_hdr.version);
+    }
+
+  if (my_error)
+    g_propagate_error (error, my_error);
+
+  return g_list_reverse (brush_list);
+}
+
+
+/*  private functions  */
+
+static GList *
+gimp_brush_load_abr_v12 (GDataInputStream  *input,
+                         AbrHeader         *abr_hdr,
+                         GFile             *file,
+                         GError           **error)
+{
+  GList *brush_list = NULL;
+  gint   i;
+
+  for (i = 0; i < abr_hdr->count; i++)
+    {
+      GimpBrush *brush;
+      GError    *my_error = NULL;
+
+      brush = gimp_brush_load_abr_brush_v12 (input, abr_hdr, i,
+                                             file, &my_error);
+
+      /*  a NULL brush without an error means an unsupported brush
+       *  type was encountered, silently skip it and try the next one
+       */
+
+      if (brush)
+        {
+          brush_list = g_list_prepend (brush_list, brush);
+        }
+      else if (my_error)
+        {
+          g_propagate_error (error, my_error);
+          break;
+        }
+    }
+
+  return brush_list;
+}
+
+static GList *
+gimp_brush_load_abr_v6 (GDataInputStream  *input,
+                        AbrHeader         *abr_hdr,
+                        GFile             *file,
+                        GError           **error)
+{
+  GList   *brush_list = NULL;
+  gint32   sample_section_size;
+  goffset  sample_section_end;
+  gint     i = 1;
+
+  if (! abr_reach_8bim_section (input, "samp", error))
+    return brush_list;
+
+  sample_section_size = abr_read_long (input, error);
+  if (error && *error)
+    return brush_list;
+
+  sample_section_end = (sample_section_size +
+                        g_seekable_tell (G_SEEKABLE (input)));
+
+  while (g_seekable_tell (G_SEEKABLE (input)) < sample_section_end)
+    {
+      GimpBrush *brush;
+      GError    *my_error = NULL;
+
+      brush = gimp_brush_load_abr_brush_v6 (input, abr_hdr, sample_section_end,
+                                            i, file, &my_error);
+
+      /*  a NULL brush without an error means an unsupported brush
+       *  type was encountered, silently skip it and try the next one
+       */
+
+      if (brush)
+        {
+          brush_list = g_list_prepend (brush_list, brush);
+        }
+      else if (my_error)
+        {
+          g_propagate_error (error, my_error);
+          break;
+        }
+
+      i++;
+    }
+
+  return brush_list;
+}
+
+static GimpBrush *
+gimp_brush_load_abr_brush_v12 (GDataInputStream  *input,
+                               AbrHeader         *abr_hdr,
+                               gint               index,
+                               GFile             *file,
+                               GError           **error)
+{
+  GimpBrush      *brush = NULL;
+  AbrBrushHeader  abr_brush_hdr;
+
+  abr_brush_hdr.type = abr_read_short (input, error);
+  if (error && *error)
+    return NULL;
+
+  abr_brush_hdr.size = abr_read_long (input, error);
+  if (error && *error)
+    return NULL;
+
+  if (abr_brush_hdr.size < 0)
+    {
+      g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                   _("Fatal parse error in brush file: "
+                     "Brush size value corrupt."));
+      return NULL;
+    }
+
+  /*  g_print(" + BRUSH\n | << type: %i  block size: %i bytes\n",
+   *          abr_brush_hdr.type, abr_brush_hdr.size);
+   */
+
+  switch (abr_brush_hdr.type)
+    {
+    case 1: /* computed brush */
+      /* FIXME: support it!
+       *
+       * We can probabaly feed the info into the generated brush code
+       * and get a usable brush back. It seems to support the same
+       * types -akl
+       */
+      g_printerr ("WARNING: computed brush unsupported, skipping.\n");
+      g_seekable_seek (G_SEEKABLE (input), abr_brush_hdr.size,
+                       G_SEEK_CUR, NULL, NULL);
+      break;
+
+    case 2: /* sampled brush */
+      {
+        AbrSampledBrushHeader  abr_sampled_brush_hdr;
+        gint                   width, height;
+        gint                   bytes;
+        gint                   size;
+        guchar                *mask;
+        gint                   i;
+        gchar                 *name;
+        gchar                 *sample_name = NULL;
+        gchar                 *tmp;
+        gshort                 compress;
+
+        abr_sampled_brush_hdr.misc = abr_read_long (input, error);
+        if (error && *error)
+          break;
+
+        abr_sampled_brush_hdr.spacing = abr_read_short (input, error);
+        if (error && *error)
+          break;
+
+        if (abr_hdr->version == 2)
+          {
+            sample_name = abr_read_ucs2_text (input, error);
+            if (error && *error)
+              break;
+          }
+
+        abr_sampled_brush_hdr.antialiasing = abr_read_char (input, error);
+        if (error && *error)
+          break;
+
+        for (i = 0; i < 4; i++)
+          {
+            abr_sampled_brush_hdr.bounds[i] = abr_read_short (input, error);
+            if (error && *error)
+              break;
+          }
+
+        for (i = 0; i < 4; i++)
+          {
+            abr_sampled_brush_hdr.bounds_long[i] = abr_read_long (input, error);
+            if (error && *error)
+              break;
+          }
+
+        abr_sampled_brush_hdr.depth = abr_read_short (input, error);
+        if (error && *error)
+          break;
+
+        height = (abr_sampled_brush_hdr.bounds_long[2] -
+                  abr_sampled_brush_hdr.bounds_long[0]); /* bottom - top */
+        width  = (abr_sampled_brush_hdr.bounds_long[3] -
+                  abr_sampled_brush_hdr.bounds_long[1]); /* right - left */
+        bytes  = abr_sampled_brush_hdr.depth >> 3;
+
+        /* g_print ("width %i  height %i  bytes %i\n", width, height, bytes); */
+
+        if (width  < 1 || width  > 10000 ||
+            height < 1 || height > 10000 ||
+            bytes  < 1 || bytes  > 1     ||
+            G_MAXSIZE / width / height / bytes < 1)
+          {
+            g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                         _("Fatal parse error in brush file: "
+                           "Brush dimensions out of range."));
+            break;
+          }
+
+        abr_sampled_brush_hdr.wide = height > 16384;
+
+        if (abr_sampled_brush_hdr.wide)
+          {
+            /* FIXME: support wide brushes */
+
+            g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                         _("Fatal parse error in brush file: "
+                           "Wide brushes are not supported."));
+            break;
+          }
+
+        tmp = g_path_get_basename (gimp_file_get_utf8_name (file));
+        if (! sample_name)
+          {
+            /* build name from filename and index */
+            name = g_strdup_printf ("%s-%03d", tmp, index);
+          }
+        else
+          {
+            /* build name from filename and sample name */
+            name = g_strdup_printf ("%s-%s", tmp, sample_name);
+            g_free (sample_name);
+          }
+        g_free (tmp);
+
+        brush = g_object_new (GIMP_TYPE_BRUSH,
+                              "name",      name,
+                              /*  FIXME: MIME type!!  */
+                              "mime-type", "application/x-photoshop-abr",
+                              NULL);
+
+        g_free (name);
+
+        brush->priv->spacing  = abr_sampled_brush_hdr.spacing;
+        brush->priv->x_axis.x = width / 2.0;
+        brush->priv->x_axis.y = 0.0;
+        brush->priv->y_axis.x = 0.0;
+        brush->priv->y_axis.y = height / 2.0;
+        brush->priv->mask     = gimp_temp_buf_new (width, height,
+                                                   babl_format ("Y u8"));
+
+        mask = gimp_temp_buf_get_data (brush->priv->mask);
+        size = width * height * bytes;
+
+        compress = abr_read_char (input, error);
+        if (error && *error)
+          {
+            g_object_unref (brush);
+            brush = NULL;
+            break;
+          }
+
+        /* g_print(" | << size: %dx%d %d bit (%d bytes) %s\n",
+         *         width, height, abr_sampled_brush_hdr.depth, size,
+         *         comppres ? "compressed" : "raw");
+         */
+
+        if (! compress)
+          {
+            gsize bytes_read;
+
+            if (! g_input_stream_read_all (G_INPUT_STREAM (input),
+                                           mask, size,
+                                           &bytes_read, NULL, error) ||
+                bytes_read != size)
+              {
+                g_object_unref (brush);
+                brush = NULL;
+                break;
+              }
+          }
+        else
+          {
+            if (! abr_rle_decode (input, (gchar *) mask, size, height, error))
+              {
+                g_object_unref (brush);
+                brush = NULL;
+                break;
+              }
+          }
+      }
+      break;
+
+    default:
+      g_printerr ("WARNING: unknown brush type, skipping.\n");
+      g_seekable_seek (G_SEEKABLE (input), abr_brush_hdr.size,
+                       G_SEEK_CUR, NULL, NULL);
+      break;
+    }
+
+  return brush;
+}
+
+static GimpBrush *
+gimp_brush_load_abr_brush_v6 (GDataInputStream  *input,
+                              AbrHeader         *abr_hdr,
+                              gint32             max_offset,
+                              gint               index,
+                              GFile             *file,
+                              GError           **error)
+{
+  GimpBrush *brush = NULL;
+  guchar    *mask;
+
+  gint32     brush_size;
+  gint32     brush_end;
+  goffset    next_brush;
+
+  gint32     top, left, bottom, right;
+  gint16     depth;
+  gchar      compress;
+
+  gint32     width, height;
+  gint32     size;
+
+  gchar     *tmp;
+  gchar     *name;
+  gboolean   r;
+
+  brush_size = abr_read_long (input, error);
+  if (error && *error)
+    return NULL;
+
+  if (brush_size < 0)
+    {
+      g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                   _("Fatal parse error in brush file: "
+                     "Brush size value corrupt."));
+      return NULL;
+    }
+
+  brush_end = brush_size;
+
+  /* complement to 4 */
+  while (brush_end % 4 != 0)
+    brush_end++;
+
+  next_brush = (brush_end + g_seekable_tell (G_SEEKABLE (input)));
+
+  if (abr_hdr->count == 1)
+    {
+      /* discard key and short coordinates and unknown short */
+      r = g_seekable_seek (G_SEEKABLE (input), 47, G_SEEK_CUR,
+                           NULL, error);
+    }
+  else
+    {
+      /* discard key and unknown bytes */
+      r = g_seekable_seek (G_SEEKABLE (input), 301, G_SEEK_CUR,
+                           NULL, error);
+    }
+
+  if (! r)
+    {
+      g_prefix_error (error,
+                      _("Fatal parse error in brush file: "
+                        "File appears truncated: "));
+      return NULL;
+    }
+
+  top      = abr_read_long  (input, error); if (error && *error) return NULL;
+  left     = abr_read_long  (input, error); if (error && *error) return NULL;
+  bottom   = abr_read_long  (input, error); if (error && *error) return NULL;
+  right    = abr_read_long  (input, error); if (error && *error) return NULL;
+  depth    = abr_read_short (input, error); if (error && *error) return NULL;
+  compress = abr_read_char  (input, error); if (error && *error) return NULL;
+
+  depth = depth >> 3;
+
+  width  = right - left;
+  height = bottom - top;
+  size   = width * depth * height;
+
+#if 0
+  g_printerr ("width %i  height %i  depth %i  compress %i\n",
+              width, height, depth, compress);
+#endif
+
+  if (width  < 1 || width  > 10000 ||
+      height < 1 || height > 10000 ||
+      depth  < 1 || depth  > 1     ||
+      G_MAXSIZE / width / height / depth < 1)
+    {
+      g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                   _("Fatal parse error in brush file: "
+                     "Brush dimensions out of range."));
+      return NULL;
+    }
+
+  if (compress < 0 || compress > 1)
+    {
+      g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                   _("Fatal parse error in brush file: "
+                     "Unknown compression method."));
+      return NULL;
+    }
+
+  tmp = g_path_get_basename (gimp_file_get_utf8_name (file));
+  name = g_strdup_printf ("%s-%03d", tmp, index);
+  g_free (tmp);
+
+  brush = g_object_new (GIMP_TYPE_BRUSH,
+                        "name",      name,
+                        /*  FIXME: MIME type!!  */
+                        "mime-type", "application/x-photoshop-abr",
+                        NULL);
+
+  g_free (name);
+
+  brush->priv->spacing  = 25; /* real value needs 8BIMdesc section parser */
+  brush->priv->x_axis.x = width / 2.0;
+  brush->priv->x_axis.y = 0.0;
+  brush->priv->y_axis.x = 0.0;
+  brush->priv->y_axis.y = height / 2.0;
+  brush->priv->mask     = gimp_temp_buf_new (width, height,
+                                             babl_format ("Y u8"));
+
+  mask = gimp_temp_buf_get_data (brush->priv->mask);
+
+  /* data decoding */
+  if (! compress)
+    {
+      /* not compressed - read raw bytes as brush data */
+      gsize bytes_read;
+
+      if (! g_input_stream_read_all (G_INPUT_STREAM (input),
+                                     mask, size,
+                                     &bytes_read, NULL, error) ||
+          bytes_read != size)
+        {
+          g_object_unref (brush);
+          return NULL;
+        }
+    }
+  else
+    {
+      if (! abr_rle_decode (input, (gchar *) mask, size, height, error))
+        {
+          g_object_unref (brush);
+          return NULL;
+        }
+    }
+
+  if (g_seekable_tell (G_SEEKABLE (input)) <= next_brush)
+    g_seekable_seek (G_SEEKABLE (input), next_brush, G_SEEK_SET,
+                     NULL, NULL);
+
+  return brush;
+}
+
+static gchar
+abr_read_char (GDataInputStream  *input,
+               GError           **error)
+{
+  return g_data_input_stream_read_byte (input, NULL, error);
+}
+
+static gint16
+abr_read_short (GDataInputStream  *input,
+                GError           **error)
+{
+  return g_data_input_stream_read_int16 (input, NULL, error);
+}
+
+static gint32
+abr_read_long (GDataInputStream  *input,
+               GError           **error)
+{
+  return g_data_input_stream_read_int32 (input, NULL, error);
+}
+
+static gchar *
+abr_read_ucs2_text (GDataInputStream  *input,
+                    GError           **error)
+{
+  gchar *name_ucs2;
+  gchar *name_utf8;
+  gint   len;
+  gint   i;
+
+  /* two-bytes characters encoded (UCS-2)
+   *  format:
+   *   long : number of characters in string
+   *   data : zero terminated UCS-2 string
+   */
+
+  len = 2 * abr_read_long (input, error);
+  if (len <= 0)
+    return NULL;
+
+  name_ucs2 = g_new (gchar, len);
+
+  for (i = 0; i < len; i++)
+    {
+      name_ucs2[i] = abr_read_char (input, error);
+      if (error && *error)
+        {
+          g_free (name_ucs2);
+          return NULL;
+        }
+    }
+
+  name_utf8 = g_convert (name_ucs2, len,
+                         "UTF-8", "UCS-2BE",
+                         NULL, NULL, NULL);
+
+  g_free (name_ucs2);
+
+  return name_utf8;
+}
+
+static gboolean
+abr_supported (AbrHeader  *abr_hdr,
+               GError    **error)
+{
+  switch (abr_hdr->version)
+    {
+    case 1:
+    case 2:
+      return TRUE;
+      break;
+
+    case 10:
+    case 6:
+      /* in this case, count contains format sub-version */
+      if (abr_hdr->count == 1 || abr_hdr->count == 2)
+        return TRUE;
+
+      g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                   _("Fatal parse error in brush file: "
+                     "Unable to decode abr format version %d."),
+
+                   /* horrid subversion display, but better than
+                    * having yet another translatable string for
+                    * this
+                    */
+                   abr_hdr->version * 10 + abr_hdr->count);
+      break;
+    }
+
+  return FALSE;
+}
+
+static gboolean
+abr_reach_8bim_section (GDataInputStream  *input,
+                        const gchar       *name,
+                        GError           **error)
+{
+  while (TRUE)
+    {
+      gchar   tag[4];
+      gchar   tagname[5];
+      guint32 section_size;
+      gsize   bytes_read;
+
+      if (! g_input_stream_read_all (G_INPUT_STREAM (input),
+                                     tag, 4,
+                                     &bytes_read, NULL, error) ||
+          bytes_read != 4)
+        return FALSE;
+
+      if (strncmp (tag, "8BIM", 4))
+        return FALSE;
+
+      if (! g_input_stream_read_all (G_INPUT_STREAM (input),
+                                     tagname, 4,
+                                     &bytes_read, NULL, error) ||
+          bytes_read != 4)
+        return FALSE;
+
+      tagname[4] = '\0';
+
+      if (! strncmp (tagname, name, 4))
+        return TRUE;
+
+      section_size = abr_read_long (input, error);
+      if (error && *error)
+        return FALSE;
+
+      if (! g_seekable_seek (G_SEEKABLE (input), section_size, G_SEEK_CUR,
+                             NULL, error))
+        return FALSE;
+    }
+
+  return FALSE;
+}
+
+static gboolean
+abr_rle_decode (GDataInputStream  *input,
+                gchar             *buffer,
+                gsize              buffer_size,
+                gint32             height,
+                GError           **error)
+{
+  gint    i, j;
+  gshort *cscanline_len = NULL;
+  gchar  *cdata         = NULL;
+  gchar  *data          = buffer;
+
+  /* read compressed size foreach scanline */
+  cscanline_len = gegl_scratch_new (gshort, height);
+  for (i = 0; i < height; i++)
+    {
+      cscanline_len[i] = abr_read_short (input, error);
+      if ((error && *error) || cscanline_len[i] <= 0)
+        goto err;
+    }
+
+  /* unpack each scanline data */
+  for (i = 0; i < height; i++)
+    {
+      gint  len;
+      gsize bytes_read;
+
+      len = cscanline_len[i];
+
+      cdata = gegl_scratch_alloc (len);
+
+      if (! g_input_stream_read_all (G_INPUT_STREAM (input),
+                                     cdata, len,
+                                     &bytes_read, NULL, error) ||
+          bytes_read != len)
+        {
+          goto err;
+        }
+
+      for (j = 0; j < len;)
+        {
+          gint32 n = cdata[j++];
+
+          if (n >= 128)     /* force sign */
+            n -= 256;
+
+          if (n < 0)
+            {
+              /* copy the following char -n + 1 times */
+
+              if (n == -128)  /* it's a nop */
+                continue;
+
+              n = -n + 1;
+
+              if (j + 1 > len || (data - buffer) + n > buffer_size)
+                goto err;
+
+              memset (data, cdata[j], n);
+
+              j    += 1;
+              data += n;
+            }
+          else
+            {
+              /* read the following n + 1 chars (no compr) */
+
+              n = n + 1;
+
+              if (j + n > len || (data - buffer) + n > buffer_size)
+                goto err;
+
+              memcpy (data, &cdata[j], n);
+
+              j    += n;
+              data += n;
+            }
+        }
+
+      g_clear_pointer (&cdata, gegl_scratch_free);
+    }
+
+  g_clear_pointer (&cscanline_len, gegl_scratch_free);
+
+  return TRUE;
+
+err:
+  g_clear_pointer (&cdata, gegl_scratch_free);
+  g_clear_pointer (&cscanline_len, gegl_scratch_free);
+  if (error && ! *error)
+    {
+      g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                   _("Fatal parse error in brush file: "
+                     "RLE compressed brush data corrupt."));
+    }
+  return FALSE;
+}
diff --git a/app/core/gimpbrush-load.h b/app/core/gimpbrush-load.h
new file mode 100644
index 0000000..6c4f0af
--- /dev/null
+++ b/app/core/gimpbrush-load.h
@@ -0,0 +1,43 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_BRUSH_LOAD_H__
+#define __GIMP_BRUSH_LOAD_H__
+
+
+#define GIMP_BRUSH_FILE_EXTENSION        ".gbr"
+#define GIMP_BRUSH_PIXMAP_FILE_EXTENSION ".gpb"
+#define GIMP_BRUSH_PS_FILE_EXTENSION     ".abr"
+#define GIMP_BRUSH_PSP_FILE_EXTENSION    ".jbr"
+
+
+GList     * gimp_brush_load        (GimpContext   *context,
+                                    GFile         *file,
+                                    GInputStream  *input,
+                                    GError       **error);
+GimpBrush * gimp_brush_load_brush  (GimpContext   *context,
+                                    GFile         *file,
+                                    GInputStream  *input,
+                                    GError       **error);
+
+GList     * gimp_brush_load_abr    (GimpContext   *context,
+                                    GFile         *file,
+                                    GInputStream  *input,
+                                    GError       **error);
+
+
+#endif /* __GIMP_BRUSH_LOAD_H__ */
diff --git a/app/core/gimpbrush-mipmap.cc b/app/core/gimpbrush-mipmap.cc
new file mode 100644
index 0000000..7c3b061
--- /dev/null
+++ b/app/core/gimpbrush-mipmap.cc
@@ -0,0 +1,514 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpbrush-mipmap.c
+ * Copyright (C) 2020 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpmath/gimpmath.h"
+
+extern "C"
+{
+
+#include "core-types.h"
+
+#include "gimpbrush.h"
+#include "gimpbrush-mipmap.h"
+#include "gimpbrush-private.h"
+#include "gimptempbuf.h"
+
+} /* extern "C" */
+
+
+#define PIXELS_PER_THREAD \
+  (/* each thread costs as much as */ 64.0 * 64.0 /* pixels */)
+
+#define GIMP_BRUSH_MIPMAP(brush, mipmaps, x, y) \
+  ((*(mipmaps))[(y) * (brush)->priv->n_horz_mipmaps + (x)])
+
+
+/*  local function prototypes  */
+
+static void                gimp_brush_mipmap_clear          (GimpBrush           *brush,
+                                                             GimpTempBuf       ***mipmaps);
+
+static const GimpTempBuf * gimp_brush_mipmap_get            (GimpBrush           *brush,
+                                                             const GimpTempBuf   *source,
+                                                             GimpTempBuf       ***mipmaps,
+                                                             gdouble             *scale_x,
+                                                             gdouble             *scale_y);
+
+static GimpTempBuf       * gimp_brush_mipmap_downscale      (const GimpTempBuf   *source);
+static GimpTempBuf       * gimp_brush_mipmap_downscale_horz (const GimpTempBuf   *source);
+static GimpTempBuf       * gimp_brush_mipmap_downscale_vert (const GimpTempBuf   *source);
+
+
+/*  private functions  */
+
+static void
+gimp_brush_mipmap_clear (GimpBrush     *brush,
+                         GimpTempBuf ***mipmaps)
+{
+  if (*mipmaps)
+    {
+      gint i;
+
+      for (i = 0;
+           i < brush->priv->n_horz_mipmaps * brush->priv->n_vert_mipmaps;
+           i++)
+        {
+          g_clear_pointer (&(*mipmaps)[i], gimp_temp_buf_unref);
+        }
+
+      g_clear_pointer (mipmaps, g_free);
+    }
+}
+
+static const GimpTempBuf *
+gimp_brush_mipmap_get (GimpBrush           *brush,
+                       const GimpTempBuf   *source,
+                       GimpTempBuf       ***mipmaps,
+                       gdouble             *scale_x,
+                       gdouble             *scale_y)
+{
+  gint x;
+  gint y;
+  gint i;
+
+  if (! source)
+    return NULL;
+
+  if (! *mipmaps)
+    {
+      gint width  = gimp_temp_buf_get_width  (source);
+      gint height = gimp_temp_buf_get_height (source);
+
+      brush->priv->n_horz_mipmaps = floor (log (width)  / M_LN2) + 1;
+      brush->priv->n_vert_mipmaps = floor (log (height) / M_LN2) + 1;
+
+      *mipmaps = g_new0 (GimpTempBuf *, brush->priv->n_horz_mipmaps *
+                                        brush->priv->n_vert_mipmaps);
+
+      GIMP_BRUSH_MIPMAP (brush, mipmaps, 0, 0) = gimp_temp_buf_ref (source);
+    }
+
+  x = floor (SAFE_CLAMP (log (1.0 / MAX (*scale_x, 0.0)) / M_LN2,
+                         0, brush->priv->n_horz_mipmaps - 1));
+  y = floor (SAFE_CLAMP (log (1.0 / MAX (*scale_y, 0.0)) / M_LN2,
+                         0, brush->priv->n_vert_mipmaps - 1));
+
+  *scale_x *= pow (2.0, x);
+  *scale_y *= pow (2.0, y);
+
+  if (GIMP_BRUSH_MIPMAP (brush, mipmaps, x, y))
+    return GIMP_BRUSH_MIPMAP (brush, mipmaps, x, y);
+
+  g_return_val_if_fail (x >= 0 || y >= 0, NULL);
+
+  for (i = 1; i <= x + y; i++)
+    {
+      gint u = x - i;
+      gint v = y;
+
+      if (u < 0)
+        {
+          v += u;
+          u  = 0;
+        }
+
+      while (u <= x && v >= 0)
+        {
+          if (GIMP_BRUSH_MIPMAP (brush, mipmaps, u, v))
+            {
+              for (; x - u > y - v; u++)
+                {
+                  GIMP_BRUSH_MIPMAP (brush, mipmaps, u + 1, v) =
+                    gimp_brush_mipmap_downscale_horz (
+                      GIMP_BRUSH_MIPMAP (brush, mipmaps, u, v));
+                }
+
+              for (; y - v > x - u; v++)
+                {
+                  GIMP_BRUSH_MIPMAP (brush, mipmaps, u, v + 1) =
+                    gimp_brush_mipmap_downscale_vert (
+                      GIMP_BRUSH_MIPMAP (brush, mipmaps, u, v));
+                }
+
+              for (; u < x; u++, v++)
+                {
+                  GIMP_BRUSH_MIPMAP (brush, mipmaps, u + 1, v + 1) =
+                    gimp_brush_mipmap_downscale (
+                      GIMP_BRUSH_MIPMAP (brush, mipmaps, u, v));
+                }
+
+              return GIMP_BRUSH_MIPMAP (brush, mipmaps, u, v);
+            }
+
+          u++;
+          v--;
+        }
+    }
+
+  g_return_val_if_reached (NULL);
+}
+
+template <class T>
+struct MipmapTraits;
+
+template <>
+struct MipmapTraits<guint8>
+{
+  static guint8
+  mix (guint8 a,
+       guint8 b)
+  {
+    return ((guint32) a + (guint32) b + 1) / 2;
+  }
+
+  static guint8
+  mix (guint8 a,
+       guint8 b,
+       guint8 c,
+       guint8 d)
+  {
+    return ((guint32) a + (guint32) b + (guint32) c + (guint32) d + 2) / 4;
+  }
+};
+
+template <>
+struct MipmapTraits<gfloat>
+{
+  static gfloat
+  mix (gfloat a,
+       gfloat b)
+  {
+    return (a + b) / 2.0;
+  }
+
+  static gfloat
+  mix (gfloat a,
+       gfloat b,
+       gfloat c,
+       gfloat d)
+  {
+    return (a + b + c + d) / 4.0;
+  }
+};
+
+template <class T,
+          gint  N>
+struct MipmapAlgorithms
+{
+  static GimpTempBuf *
+  downscale (const GimpTempBuf *source)
+  {
+    GimpTempBuf *destination;
+    gint         width  = gimp_temp_buf_get_width  (source);
+    gint         height = gimp_temp_buf_get_height (source);
+
+    width  /= 2;
+    height /= 2;
+
+    destination = gimp_temp_buf_new (width, height,
+                                     gimp_temp_buf_get_format (source));
+
+    gegl_parallel_distribute_area (
+      GEGL_RECTANGLE (0, 0, width, height), PIXELS_PER_THREAD,
+      [=] (const GeglRectangle *area)
+      {
+        const T *src0        = (const T *) gimp_temp_buf_get_data (source);
+        T       *dest0       = (T       *) gimp_temp_buf_get_data (destination);
+        gint     src_stride  = N * gimp_temp_buf_get_width (source);
+        gint     dest_stride = N * gimp_temp_buf_get_width (destination);
+        gint     y;
+
+        src0  += 2 * (area->y * src_stride  + N * area->x);
+        dest0 +=      area->y * dest_stride + N * area->x;
+
+        for (y = 0; y < area->height; y++)
+          {
+            const T *src  = src0;
+            T       *dest = dest0;
+            gint     x;
+
+            for (x = 0; x < area->width; x++)
+              {
+                gint c;
+
+                for (c = 0; c < N; c++)
+                  {
+                    dest[c] = MipmapTraits<T>::mix (src[c],
+                                                    src[N + c],
+                                                    src[src_stride + c],
+                                                    src[src_stride + N + c]);
+                  }
+
+                src  += 2 * N;
+                dest += N;
+              }
+
+            src0  += 2 * src_stride;
+            dest0 += dest_stride;
+          }
+      });
+
+    return destination;
+  }
+
+  static GimpTempBuf *
+  downscale_horz (const GimpTempBuf *source)
+  {
+    GimpTempBuf *destination;
+    gint         width  = gimp_temp_buf_get_width  (source);
+    gint         height = gimp_temp_buf_get_height (source);
+
+    width /= 2;
+
+    destination = gimp_temp_buf_new (width, height,
+                                     gimp_temp_buf_get_format (source));
+
+    gegl_parallel_distribute_range (
+      height, PIXELS_PER_THREAD / width,
+      [=] (gint offset,
+           gint size)
+      {
+        const T *src0        = (const T *) gimp_temp_buf_get_data (source);
+        T       *dest0       = (T       *) gimp_temp_buf_get_data (destination);
+        gint     src_stride  = N * gimp_temp_buf_get_width (source);
+        gint     dest_stride = N * gimp_temp_buf_get_width (destination);
+        gint     y;
+
+        src0  += offset * src_stride;
+        dest0 += offset * dest_stride;
+
+        for (y = 0; y < size; y++)
+          {
+            const T *src  = src0;
+            T       *dest = dest0;
+            gint     x;
+
+            for (x = 0; x < width; x++)
+              {
+                gint c;
+
+                for (c = 0; c < N; c++)
+                  dest[c] = MipmapTraits<T>::mix (src[c], src[N + c]);
+
+                src  += 2 * N;
+                dest += N;
+              }
+
+            src0  += src_stride;
+            dest0 += dest_stride;
+          }
+      });
+
+    return destination;
+  }
+
+  static GimpTempBuf *
+  downscale_vert (const GimpTempBuf *source)
+  {
+    GimpTempBuf *destination;
+    gint         width  = gimp_temp_buf_get_width  (source);
+    gint         height = gimp_temp_buf_get_height (source);
+
+    height /= 2;
+
+    destination = gimp_temp_buf_new (width, height,
+                                     gimp_temp_buf_get_format (source));
+
+    gegl_parallel_distribute_range (
+      width, PIXELS_PER_THREAD / height,
+      [=] (gint offset,
+           gint size)
+      {
+        const T *src0        = (const T *) gimp_temp_buf_get_data (source);
+        T       *dest0       = (T       *) gimp_temp_buf_get_data (destination);
+        gint     src_stride  = N * gimp_temp_buf_get_width (source);
+        gint     dest_stride = N * gimp_temp_buf_get_width (destination);
+        gint     x;
+
+        src0  += offset * N;
+        dest0 += offset * N;
+
+        for (x = 0; x < size; x++)
+          {
+            const T *src  = src0;
+            T       *dest = dest0;
+            gint     y;
+
+            for (y = 0; y < height; y++)
+              {
+                gint c;
+
+                for (c = 0; c < N; c++)
+                  dest[c] = MipmapTraits<T>::mix (src[c], src[src_stride + c]);
+
+                src  += 2 * src_stride;
+                dest += dest_stride;
+              }
+
+            src0  += N;
+            dest0 += N;
+          }
+      });
+
+    return destination;
+  }
+};
+
+template <class Func>
+static GimpTempBuf *
+gimp_brush_mipmap_dispatch (const GimpTempBuf *source,
+                            Func               func)
+{
+  const Babl *format = gimp_temp_buf_get_format (source);
+  const Babl *type;
+  gint        n_components;
+
+  type         = babl_format_get_type (format, 0);
+  n_components = babl_format_get_n_components (format);
+
+  if (type == babl_type ("u8"))
+    {
+      switch (n_components)
+        {
+        case 1:
+          return func (MipmapAlgorithms<guint8, 1> ());
+
+        case 3:
+          return func (MipmapAlgorithms<guint8, 3> ());
+        }
+    }
+  else if (type == babl_type ("float"))
+    {
+      switch (n_components)
+        {
+        case 1:
+          return func (MipmapAlgorithms<gfloat, 1> ());
+
+        case 3:
+          return func (MipmapAlgorithms<gfloat, 3> ());
+        }
+    }
+
+  g_return_val_if_reached (NULL);
+}
+
+static GimpTempBuf *
+gimp_brush_mipmap_downscale (const GimpTempBuf *source)
+{
+  return gimp_brush_mipmap_dispatch (
+    source,
+    [&] (auto algorithms)
+    {
+      return algorithms.downscale (source);
+    });
+}
+
+static GimpTempBuf *
+gimp_brush_mipmap_downscale_horz (const GimpTempBuf *source)
+{
+  return gimp_brush_mipmap_dispatch (
+    source,
+    [&] (auto algorithms)
+    {
+      return algorithms.downscale_horz (source);
+    });
+}
+
+static GimpTempBuf *
+gimp_brush_mipmap_downscale_vert (const GimpTempBuf *source)
+{
+  return gimp_brush_mipmap_dispatch (
+    source,
+    [&] (auto algorithms)
+    {
+      return algorithms.downscale_vert (source);
+    });
+}
+
+
+/*  public functions  */
+
+void
+gimp_brush_mipmap_clear (GimpBrush *brush)
+{
+  gimp_brush_mipmap_clear (brush, &brush->priv->mask_mipmaps);
+  gimp_brush_mipmap_clear (brush, &brush->priv->pixmap_mipmaps);
+}
+
+const GimpTempBuf *
+gimp_brush_mipmap_get_mask (GimpBrush *brush,
+                            gdouble   *scale_x,
+                            gdouble   *scale_y)
+{
+  return gimp_brush_mipmap_get (brush,
+                                brush->priv->mask,
+                                &brush->priv->mask_mipmaps,
+                                scale_x, scale_y);
+}
+
+const GimpTempBuf *
+gimp_brush_mipmap_get_pixmap (GimpBrush *brush,
+                              gdouble   *scale_x,
+                              gdouble   *scale_y)
+{
+  return gimp_brush_mipmap_get (brush,
+                                brush->priv->pixmap,
+                                &brush->priv->pixmap_mipmaps,
+                                scale_x, scale_y);
+}
+
+gsize
+gimp_brush_mipmap_get_memsize (GimpBrush *brush)
+{
+  gsize memsize = 0;
+
+  if (brush->priv->mask_mipmaps)
+    {
+      gint i;
+
+      for (i = 1;
+           i < brush->priv->n_horz_mipmaps * brush->priv->n_vert_mipmaps;
+           i++)
+        {
+          memsize += gimp_temp_buf_get_memsize (brush->priv->mask_mipmaps[i]);
+        }
+    }
+
+  if (brush->priv->pixmap_mipmaps)
+    {
+      gint i;
+
+      for (i = 1;
+           i < brush->priv->n_horz_mipmaps * brush->priv->n_vert_mipmaps;
+           i++)
+        {
+          memsize += gimp_temp_buf_get_memsize (brush->priv->pixmap_mipmaps[i]);
+        }
+    }
+
+  return memsize;
+}
diff --git a/app/core/gimpbrush-mipmap.h b/app/core/gimpbrush-mipmap.h
new file mode 100644
index 0000000..b2b8fd3
--- /dev/null
+++ b/app/core/gimpbrush-mipmap.h
@@ -0,0 +1,38 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpbrush-mipmap.h
+ * Copyright (C) 2020 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_BRUSH_MIPMAP_H__
+#define __GIMP_BRUSH_MIPMAP_H__
+
+
+void                gimp_brush_mipmap_clear       (GimpBrush *brush);
+
+const GimpTempBuf * gimp_brush_mipmap_get_mask    (GimpBrush *brush,
+                                                   gdouble   *scale_x,
+                                                   gdouble   *scale_y);
+
+const GimpTempBuf * gimp_brush_mipmap_get_pixmap  (GimpBrush *brush,
+                                                   gdouble   *scale_x,
+                                                   gdouble   *scale_y);
+
+gsize               gimp_brush_mipmap_get_memsize (GimpBrush *brush);
+
+
+#endif  /*  __GIMP_BRUSH_MIPMAP_H__  */
diff --git a/app/core/gimpbrush-private.h b/app/core/gimpbrush-private.h
new file mode 100644
index 0000000..c8d4d29
--- /dev/null
+++ b/app/core/gimpbrush-private.h
@@ -0,0 +1,47 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_BRUSH_PRIVATE_H__
+#define __GIMP_BRUSH_PRIVATE_H__
+
+
+struct _GimpBrushPrivate
+{
+  GimpTempBuf     *mask;           /*  the actual mask                    */
+  GimpTempBuf     *blurred_mask;    /*  blurred actual mask cached          */
+  GimpTempBuf     *pixmap;         /*  optional pixmap data               */
+  GimpTempBuf     *blurred_pixmap;  /*  optional pixmap data blurred cache  */
+
+  gdouble          blur_hardness;
+
+  gint             n_horz_mipmaps;
+  gint             n_vert_mipmaps;
+  GimpTempBuf    **mask_mipmaps;
+  GimpTempBuf    **pixmap_mipmaps;
+
+  gint             spacing;    /*  brush's spacing                */
+  GimpVector2      x_axis;     /*  for calculating brush spacing  */
+  GimpVector2      y_axis;     /*  for calculating brush spacing  */
+
+  gint             use_count;  /*  for keeping the caches alive   */
+  GimpBrushCache  *mask_cache;
+  GimpBrushCache  *pixmap_cache;
+  GimpBrushCache  *boundary_cache;
+};
+
+
+#endif /* __GIMP_BRUSH_PRIVATE_H__ */
diff --git a/app/core/gimpbrush-save.c b/app/core/gimpbrush-save.c
new file mode 100644
index 0000000..38d4bcd
--- /dev/null
+++ b/app/core/gimpbrush-save.c
@@ -0,0 +1,107 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "core-types.h"
+
+#include "gimpbrush.h"
+#include "gimpbrush-header.h"
+#include "gimpbrush-save.h"
+#include "gimptempbuf.h"
+
+
+gboolean
+gimp_brush_save (GimpData       *data,
+                 GOutputStream  *output,
+                 GError        **error)
+{
+  GimpBrush       *brush  = GIMP_BRUSH (data);
+  GimpTempBuf     *mask   = gimp_brush_get_mask (brush);
+  GimpTempBuf     *pixmap = gimp_brush_get_pixmap (brush);
+  GimpBrushHeader  header;
+  const gchar     *name;
+  gint             width;
+  gint             height;
+
+  name   = gimp_object_get_name (brush);
+  width  = gimp_temp_buf_get_width  (mask);
+  height = gimp_temp_buf_get_height (mask);
+
+  header.header_size  = g_htonl (sizeof (GimpBrushHeader) +
+                                 strlen (name) + 1);
+  header.version      = g_htonl (2);
+  header.width        = g_htonl (width);
+  header.height       = g_htonl (height);
+  header.bytes        = g_htonl (pixmap ? 4 : 1);
+  header.magic_number = g_htonl (GIMP_BRUSH_MAGIC);
+  header.spacing      = g_htonl (gimp_brush_get_spacing (brush));
+
+  if (! g_output_stream_write_all (output, &header, sizeof (header),
+                                   NULL, NULL, error))
+    {
+      return FALSE;
+    }
+
+  if (! g_output_stream_write_all (output, name, strlen (name) + 1,
+                                   NULL, NULL, error))
+    {
+      return FALSE;
+    }
+
+  if (pixmap)
+    {
+      gsize   size = width * height * 4;
+      guchar *data = g_malloc (size);
+      guchar *p    = gimp_temp_buf_get_data (pixmap);
+      guchar *m    = gimp_temp_buf_get_data (mask);
+      guchar *d    = data;
+      gint    i;
+
+      for (i = 0; i < width * height; i++)
+        {
+          *d++ = *p++;
+          *d++ = *p++;
+          *d++ = *p++;
+          *d++ = *m++;
+        }
+
+      if (! g_output_stream_write_all (output, data, size,
+                                       NULL, NULL, error))
+        {
+          g_free (data);
+
+          return FALSE;
+        }
+
+      g_free (data);
+    }
+  else
+    {
+      if (! g_output_stream_write_all (output,
+                                       gimp_temp_buf_get_data (mask),
+                                       gimp_temp_buf_get_data_size (mask),
+                                       NULL, NULL, error))
+        {
+          return FALSE;
+        }
+    }
+
+  return TRUE;
+}
diff --git a/app/core/gimpbrush-save.h b/app/core/gimpbrush-save.h
new file mode 100644
index 0000000..f400cf0
--- /dev/null
+++ b/app/core/gimpbrush-save.h
@@ -0,0 +1,28 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_BRUSH_SAVE_H__
+#define __GIMP_BRUSH_SAVE_H__
+
+
+/*  don't call this function directly, use gimp_data_save() instead  */
+gboolean   gimp_brush_save (GimpData       *data,
+                            GOutputStream  *output,
+                            GError        **error);
+
+
+#endif  /*  __GIMP_BRUSH_SAVE_H__  */
diff --git a/app/core/gimpbrush-transform.cc b/app/core/gimpbrush-transform.cc
new file mode 100644
index 0000000..45673cd
--- /dev/null
+++ b/app/core/gimpbrush-transform.cc
@@ -0,0 +1,1043 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpbrush-transform.c
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpmath/gimpmath.h"
+
+extern "C"
+{
+
+#include "core-types.h"
+
+#include "gegl/gimp-gegl-loops.h"
+
+#include "gimpbrush.h"
+#include "gimpbrush-mipmap.h"
+#include "gimpbrush-transform.h"
+#include "gimptempbuf.h"
+
+
+#define PIXELS_PER_THREAD \
+  (/* each thread costs as much as */ 64.0 * 64.0 /* pixels */)
+
+
+/*  local function prototypes  */
+
+static void    gimp_brush_transform_bounding_box           (const GimpTempBuf *temp_buf,
+                                                            const GimpMatrix3 *matrix,
+                                                            gint              *x,
+                                                            gint              *y,
+                                                            gint              *width,
+                                                            gint              *height);
+
+static void    gimp_brush_transform_blur                   (GimpTempBuf       *buf,
+                                                            gint               r);
+static gint    gimp_brush_transform_blur_radius            (gint               height,
+                                                            gint               width,
+                                                            gdouble            hardness);
+static void    gimp_brush_transform_adjust_hardness_matrix (gdouble            width,
+                                                            gdouble            height,
+                                                            gdouble            blur_radius,
+                                                            GimpMatrix3       *matrix);
+
+
+/*  public functions  */
+
+void
+gimp_brush_real_transform_size (GimpBrush *brush,
+                                gdouble    scale,
+                                gdouble    aspect_ratio,
+                                gdouble    angle,
+                                gboolean   reflect,
+                                gint      *width,
+                                gint      *height)
+{
+  const GimpTempBuf *source;
+  GimpMatrix3        matrix;
+  gdouble            scale_x, scale_y;
+  gint               x, y;
+
+  gimp_brush_transform_get_scale (scale, aspect_ratio,
+                                  &scale_x, &scale_y);
+
+  source = gimp_brush_mipmap_get_mask (brush, &scale_x, &scale_y);
+
+  gimp_brush_transform_matrix (gimp_temp_buf_get_width  (source),
+                               gimp_temp_buf_get_height (source),
+                               scale_x, scale_y, angle, reflect, &matrix);
+
+  gimp_brush_transform_bounding_box (source, &matrix, &x, &y, width, height);
+}
+
+/*
+ * Transforms the brush mask with bilinear interpolation.
+ *
+ * Rather than calculating the inverse transform for each point in the
+ * transformed image, this algorithm uses the inverse transformed
+ * corner points of the destination image to work out the starting
+ * position in the source image and the U and V deltas in the source
+ * image space.  It then uses a scan-line approach, looping through
+ * rows and columns in the transformed (destination) image while
+ * walking along the corresponding rows and columns (named U and V) in
+ * the source image.
+ *
+ * The horizontal in destination space (transform result) is reverse
+ * transformed into source image space to get U.  The vertical in
+ * destination space (transform result) is reverse transformed into
+ * source image space to get V.
+ *
+ * The strength of this particular algorithm is that calculation work
+ * should depend more upon the final transformed brush size rather
+ * than the input brush size.
+ *
+ * There are no floating point calculations in the inner loop for speed.
+ *
+ * Some variables end with the suffix _i to indicate they have been
+ * premultiplied by int_multiple
+ */
+GimpTempBuf *
+gimp_brush_real_transform_mask (GimpBrush *brush,
+                                gdouble    scale,
+                                gdouble    aspect_ratio,
+                                gdouble    angle,
+                                gboolean   reflect,
+                                gdouble    hardness)
+{
+  GimpTempBuf       *result;
+  const GimpTempBuf *source;
+  const guchar      *src;
+  GimpMatrix3        matrix;
+  gdouble            scale_x, scale_y;
+  gint               src_width;
+  gint               src_height;
+  gint               src_width_minus_one;
+  gint               src_height_minus_one;
+  gint               dest_width;
+  gint               dest_height;
+  gint               blur_radius;
+  gint               x, y;
+  gdouble            b_lx, b_rx, t_lx, t_rx;
+  gdouble            b_ly, b_ry, t_ly, t_ry;
+  gdouble            src_tl_to_tr_delta_x;
+  gdouble            src_tl_to_tr_delta_y;
+  gdouble            src_tl_to_bl_delta_x;
+  gdouble            src_tl_to_bl_delta_y;
+  gint               src_walk_ux_i;
+  gint               src_walk_uy_i;
+  gint               src_walk_vx_i;
+  gint               src_walk_vy_i;
+  gint               src_x_min_i;
+  gint               src_y_min_i;
+  gint               src_x_max_i;
+  gint               src_y_max_i;
+
+  /*
+   * tl, tr etc are used because it is easier to visualize top left,
+   * top right etc corners of the forward transformed source image
+   * rectangle.
+   */
+  const gint fraction_bits = 12;
+  const gint int_multiple  = pow (2, fraction_bits);
+
+  /* In inner loop's bilinear calculation, two numbers that were each
+   * previously multiplied by int_multiple are multiplied together.
+   * To get back the right result, the multiplication result must be
+   * divided *twice* by 2^fraction_bits, equivalent to bit shift right
+   * by 2 * fraction_bits
+   */
+  const gint recovery_bits = 2 * fraction_bits;
+
+  /*
+   * example: suppose fraction_bits = 9
+   * a 9-bit mask looks like this: 0001 1111 1111
+   * and is given by:  2^fraction_bits - 1
+   * demonstration:
+   * 2^0     = 0000 0000 0001
+   * 2^1     = 0000 0000 0010
+   * :
+   * 2^8     = 0001 0000 0000
+   * 2^9     = 0010 0000 0000
+   * 2^9 - 1 = 0001 1111 1111
+   */
+  const guint fraction_bitmask = pow(2, fraction_bits) - 1 ;
+
+  gimp_brush_transform_get_scale (scale, aspect_ratio,
+                                  &scale_x, &scale_y);
+
+  source = gimp_brush_mipmap_get_mask (brush, &scale_x, &scale_y);
+
+  src_width  = gimp_temp_buf_get_width  (source);
+  src_height = gimp_temp_buf_get_height (source);
+
+  gimp_brush_transform_matrix (src_width, src_height,
+                               scale_x, scale_y, angle, reflect, &matrix);
+
+  if (gimp_matrix3_is_identity (&matrix) && hardness == 1.0)
+    return gimp_temp_buf_copy (source);
+
+  src_width_minus_one  = src_width  - 1;
+  src_height_minus_one = src_height - 1;
+
+  gimp_brush_transform_bounding_box (source, &matrix,
+                                     &x, &y, &dest_width, &dest_height);
+
+  blur_radius = 0;
+
+  if (hardness < 1.0)
+    {
+      GimpMatrix3 unrotated_matrix;
+      gint        unrotated_x;
+      gint        unrotated_y;
+      gint        unrotated_dest_width;
+      gint        unrotated_dest_height;
+
+      gimp_brush_transform_matrix (src_width, src_height,
+                                   scale_x, scale_y, 0.0, FALSE,
+                                   &unrotated_matrix);
+
+      gimp_brush_transform_bounding_box (source, &unrotated_matrix,
+                                         &unrotated_x, &unrotated_y,
+                                         &unrotated_dest_width,
+                                         &unrotated_dest_height);
+
+      blur_radius = gimp_brush_transform_blur_radius (unrotated_dest_width,
+                                                      unrotated_dest_height,
+                                                      hardness);
+
+      gimp_brush_transform_adjust_hardness_matrix (dest_width, dest_height,
+                                                   blur_radius, &matrix);
+    }
+
+  gimp_matrix3_translate (&matrix, -x, -y);
+  gimp_matrix3_invert (&matrix);
+  gimp_matrix3_translate (&matrix, -0.5, -0.5);
+
+  result = gimp_temp_buf_new (dest_width, dest_height,
+                              gimp_temp_buf_get_format (source));
+
+  src = gimp_temp_buf_get_data (source);
+
+  /* prevent disappearance of 1x1 pixel brush at some rotations when
+     scaling < 1 */
+  /*
+  if (src_width == 1 && src_height == 1 && scale_x < 1 && scale_y < 1 )
+    {
+      *dest = src[0];
+      return result;
+    }*/
+
+  gimp_matrix3_transform_point (&matrix,
+                                0.5,              0.5,
+                                &t_lx,            &t_ly);
+  gimp_matrix3_transform_point (&matrix,
+                                dest_width - 0.5, 0.5,
+                                &t_rx,            &t_ry);
+  gimp_matrix3_transform_point (&matrix,
+                                0.5,              dest_height - 0.5,
+                                &b_lx,            &b_ly);
+  gimp_matrix3_transform_point (&matrix,
+                                dest_width - 0.5, dest_height - 0.5,
+                                &b_rx,            &b_ry);
+
+  /* in image space, calc U (what was horizontal originally)
+   * note: double precision
+   */
+  src_tl_to_tr_delta_x = t_rx - t_lx;
+  src_tl_to_tr_delta_y = t_ry - t_ly;
+
+  /* in image space, calc V (what was vertical originally)
+   * note: double precision
+   */
+  src_tl_to_bl_delta_x = b_lx - t_lx;
+  src_tl_to_bl_delta_y = b_ly - t_ly;
+
+  /* speed optimized, note conversion to int precision */
+  src_walk_ux_i = (gint) ((src_tl_to_tr_delta_x / MAX (dest_width  - 1, 1)) *
+                          int_multiple);
+  src_walk_uy_i = (gint) ((src_tl_to_tr_delta_y / MAX (dest_width  - 1, 1)) *
+                          int_multiple);
+  src_walk_vx_i = (gint) ((src_tl_to_bl_delta_x / MAX (dest_height - 1, 1)) *
+                          int_multiple);
+  src_walk_vy_i = (gint) ((src_tl_to_bl_delta_y / MAX (dest_height - 1, 1)) *
+                          int_multiple);
+
+  src_x_min_i = -int_multiple / 2;
+  src_y_min_i = -int_multiple / 2;
+
+  src_x_max_i = src_width  * int_multiple - int_multiple / 2;
+  src_y_max_i = src_height * int_multiple - int_multiple / 2;
+
+  gegl_parallel_distribute_area (
+    GEGL_RECTANGLE (0, 0, dest_width, dest_height), PIXELS_PER_THREAD,
+    [=] (const GeglRectangle *area)
+    {
+      guchar       *dest;
+      gint          src_space_cur_pos_x;
+      gint          src_space_cur_pos_y;
+      gint          src_space_cur_pos_x_i;
+      gint          src_space_cur_pos_y_i;
+      gint          src_space_row_start_x_i;
+      gint          src_space_row_start_y_i;
+      const guchar *src_walker;
+      const guchar *pixel_next;
+      const guchar *pixel_below;
+      const guchar *pixel_below_next;
+      gint          opposite_x, distance_from_true_x;
+      gint          opposite_y, distance_from_true_y;
+      gint          u, v;
+
+      dest = gimp_temp_buf_get_data (result) +
+             dest_width * area->y + area->x;
+
+      /* initialize current position in source space to the start position (tl)
+       * speed optimized, note conversion to int precision
+       */
+      src_space_row_start_x_i = (gint) (t_lx * int_multiple) +
+                                src_walk_vx_i * area->y      +
+                                src_walk_ux_i * area->x;
+      src_space_row_start_y_i = (gint) (t_ly * int_multiple) +
+                                src_walk_vy_i * area->y      +
+                                src_walk_uy_i * area->x;
+
+      for (v = 0; v < area->height; v++)
+        {
+          src_space_cur_pos_x_i = src_space_row_start_x_i;
+          src_space_cur_pos_y_i = src_space_row_start_y_i;
+
+          for (u = 0; u < area->width; u++)
+            {
+              if (src_space_cur_pos_x_i <  src_x_min_i ||
+                  src_space_cur_pos_x_i >= src_x_max_i ||
+                  src_space_cur_pos_y_i <  src_y_min_i ||
+                  src_space_cur_pos_y_i >= src_y_max_i)
+                  /* no corresponding pixel in source space */
+                {
+                  *dest = 0;
+                }
+              else /* reverse transformed point hits source pixel */
+                {
+                  src_space_cur_pos_x = src_space_cur_pos_x_i >> fraction_bits;
+                  src_space_cur_pos_y = src_space_cur_pos_y_i >> fraction_bits;
+
+                  src_walker = src                             +
+                               src_space_cur_pos_y * src_width +
+                               src_space_cur_pos_x;
+
+                  pixel_next       = src_walker + 1;
+                  pixel_below      = src_walker + src_width;
+                  pixel_below_next = pixel_below + 1;
+
+                  if (src_space_cur_pos_x < 0)
+                    {
+                      src_walker  = pixel_next;
+                      pixel_below = pixel_below_next;
+                    }
+                  else if (src_space_cur_pos_x >= src_width_minus_one)
+                    {
+                      pixel_next       = src_walker;
+                      pixel_below_next = pixel_below;
+                    }
+
+                  if (src_space_cur_pos_y < 0)
+                    {
+                      src_walker = pixel_below;
+                      pixel_next = pixel_below_next;
+                    }
+                  else if (src_space_cur_pos_y >= src_height_minus_one)
+                    {
+                      pixel_below      = src_walker;
+                      pixel_below_next = pixel_next;
+                    }
+
+                  distance_from_true_x = src_space_cur_pos_x_i & fraction_bitmask;
+                  distance_from_true_y = src_space_cur_pos_y_i & fraction_bitmask;
+                  opposite_x =  int_multiple - distance_from_true_x;
+                  opposite_y =  int_multiple - distance_from_true_y;
+
+                  *dest = ((src_walker[0] * opposite_x +
+                            pixel_next[0] * distance_from_true_x) * opposite_y +
+                           (pixel_below[0] * opposite_x +
+                            pixel_below_next[0] *distance_from_true_x) * distance_from_true_y
+                           ) >> recovery_bits;
+                }
+
+              src_space_cur_pos_x_i += src_walk_ux_i;
+              src_space_cur_pos_y_i += src_walk_uy_i;
+
+              dest++;
+            } /* end for x */
+
+          src_space_row_start_x_i += src_walk_vx_i;
+          src_space_row_start_y_i += src_walk_vy_i;
+
+          dest += dest_width - area->width;
+        } /* end for y */
+    });
+
+  gimp_brush_transform_blur (result, blur_radius);
+
+  return result;
+}
+
+/*
+ * Transforms the brush pixmap with bilinear interpolation.
+ *
+ * The algorithm used is exactly the same as for the brush mask
+ * (gimp_brush_real_transform_mask) except it accounts for 3 color channels
+ *  instead of 1 grayscale channel.
+ *
+ * Rather than calculating the inverse transform for each point in the
+ * transformed image, this algorithm uses the inverse transformed
+ * corner points of the destination image to work out the starting
+ * position in the source image and the U and V deltas in the source
+ * image space.  It then uses a scan-line approach, looping through
+ * rows and columns in the transformed (destination) image while
+ * walking along the corresponding rows and columns (named U and V) in
+ * the source image.
+ *
+ * The horizontal in destination space (transform result) is reverse
+ * transformed into source image space to get U.  The vertical in
+ * destination space (transform result) is reverse transformed into
+ * source image space to get V.
+ *
+ * The strength of this particular algorithm is that calculation work
+ * should depend more upon the final transformed brush size rather
+ * than the input brush size.
+ *
+ * There are no floating point calculations in the inner loop for speed.
+ *
+ * Some variables end with the suffix _i to indicate they have been
+ * premultiplied by int_multiple
+ */
+GimpTempBuf *
+gimp_brush_real_transform_pixmap (GimpBrush *brush,
+                                  gdouble    scale,
+                                  gdouble    aspect_ratio,
+                                  gdouble    angle,
+                                  gboolean   reflect,
+                                  gdouble    hardness)
+{
+  GimpTempBuf       *result;
+  const GimpTempBuf *source;
+  const guchar      *src;
+  GimpMatrix3        matrix;
+  gdouble            scale_x, scale_y;
+  gint               src_width;
+  gint               src_height;
+  gint               src_width_minus_one;
+  gint               src_height_minus_one;
+  gint               dest_width;
+  gint               dest_height;
+  gint               blur_radius;
+  gint               x, y;
+  gdouble            b_lx, b_rx, t_lx, t_rx;
+  gdouble            b_ly, b_ry, t_ly, t_ry;
+  gdouble            src_tl_to_tr_delta_x;
+  gdouble            src_tl_to_tr_delta_y;
+  gdouble            src_tl_to_bl_delta_x;
+  gdouble            src_tl_to_bl_delta_y;
+  gint               src_walk_ux_i;
+  gint               src_walk_uy_i;
+  gint               src_walk_vx_i;
+  gint               src_walk_vy_i;
+  gint               src_x_min_i;
+  gint               src_y_min_i;
+  gint               src_x_max_i;
+  gint               src_y_max_i;
+
+  /*
+   * tl, tr etc are used because it is easier to visualize top left,
+   * top right etc corners of the forward transformed source image
+   * rectangle.
+   */
+  const gint fraction_bits = 12;
+  const gint int_multiple  = pow (2, fraction_bits);
+
+  /* In inner loop's bilinear calculation, two numbers that were each
+   * previously multiplied by int_multiple are multiplied together.
+   * To get back the right result, the multiplication result must be
+   * divided *twice* by 2^fraction_bits, equivalent to bit shift right
+   * by 2 * fraction_bits
+   */
+  const gint recovery_bits = 2 * fraction_bits;
+
+  /*
+   * example: suppose fraction_bits = 9
+   * a 9-bit mask looks like this: 0001 1111 1111
+   * and is given by:  2^fraction_bits - 1
+   * demonstration:
+   * 2^0     = 0000 0000 0001
+   * 2^1     = 0000 0000 0010
+   * :
+   * 2^8     = 0001 0000 0000
+   * 2^9     = 0010 0000 0000
+   * 2^9 - 1 = 0001 1111 1111
+   */
+  const guint fraction_bitmask = pow(2, fraction_bits) - 1 ;
+
+  gimp_brush_transform_get_scale (scale, aspect_ratio,
+                                  &scale_x, &scale_y);
+
+  source = gimp_brush_mipmap_get_pixmap (brush, &scale_x, &scale_y);
+
+  src_width  = gimp_temp_buf_get_width  (source);
+  src_height = gimp_temp_buf_get_height (source);
+
+  gimp_brush_transform_matrix (src_width, src_height,
+                               scale_x, scale_y, angle, reflect, &matrix);
+
+  if (gimp_matrix3_is_identity (&matrix) && hardness == 1.0)
+    return gimp_temp_buf_copy (source);
+
+  src_width_minus_one  = src_width  - 1;
+  src_height_minus_one = src_height - 1;
+
+  gimp_brush_transform_bounding_box (source, &matrix,
+                                     &x, &y, &dest_width, &dest_height);
+
+  blur_radius = 0;
+
+  if (hardness < 1.0)
+    {
+      GimpMatrix3 unrotated_matrix;
+      gint        unrotated_x;
+      gint        unrotated_y;
+      gint        unrotated_dest_width;
+      gint        unrotated_dest_height;
+
+      gimp_brush_transform_matrix (src_width, src_height,
+                                   scale_x, scale_y, 0.0, FALSE,
+                                   &unrotated_matrix);
+
+      gimp_brush_transform_bounding_box (source, &unrotated_matrix,
+                                         &unrotated_x, &unrotated_y,
+                                         &unrotated_dest_width,
+                                         &unrotated_dest_height);
+
+      blur_radius = gimp_brush_transform_blur_radius (unrotated_dest_width,
+                                                      unrotated_dest_height,
+                                                      hardness);
+
+      gimp_brush_transform_adjust_hardness_matrix (dest_width, dest_height,
+                                                   blur_radius, &matrix);
+    }
+
+  gimp_matrix3_translate (&matrix, -x, -y);
+  gimp_matrix3_invert (&matrix);
+  gimp_matrix3_translate (&matrix, -0.5, -0.5);
+
+  result = gimp_temp_buf_new (dest_width, dest_height,
+                              gimp_temp_buf_get_format (source));
+
+  src = gimp_temp_buf_get_data (source);
+
+  /* prevent disappearance of 1x1 pixel brush at some rotations when
+     scaling < 1 */
+  /*
+  if (src_width == 1 && src_height == 1 && scale_x < 1 && scale_y < 1 )
+    {
+      *dest = src[0];
+      return result;
+    }*/
+
+  gimp_matrix3_transform_point (&matrix,
+                                0.5,              0.5,
+                                &t_lx,            &t_ly);
+  gimp_matrix3_transform_point (&matrix,
+                                dest_width - 0.5, 0.5,
+                                &t_rx,            &t_ry);
+  gimp_matrix3_transform_point (&matrix,
+                                0.5,              dest_height - 0.5,
+                                &b_lx,            &b_ly);
+  gimp_matrix3_transform_point (&matrix,
+                                dest_width - 0.5, dest_height - 0.5,
+                                &b_rx,            &b_ry);
+
+  /* in image space, calc U (what was horizontal originally)
+   * note: double precision
+   */
+  src_tl_to_tr_delta_x = t_rx - t_lx;
+  src_tl_to_tr_delta_y = t_ry - t_ly;
+
+  /* in image space, calc V (what was vertical originally)
+   * note: double precision
+   */
+  src_tl_to_bl_delta_x = b_lx - t_lx;
+  src_tl_to_bl_delta_y = b_ly - t_ly;
+
+  /* speed optimized, note conversion to int precision */
+  src_walk_ux_i = (gint) ((src_tl_to_tr_delta_x / MAX (dest_width  - 1, 1)) *
+                          int_multiple);
+  src_walk_uy_i = (gint) ((src_tl_to_tr_delta_y / MAX (dest_width  - 1, 1)) *
+                          int_multiple);
+  src_walk_vx_i = (gint) ((src_tl_to_bl_delta_x / MAX (dest_height - 1, 1)) *
+                          int_multiple);
+  src_walk_vy_i = (gint) ((src_tl_to_bl_delta_y / MAX (dest_height - 1, 1)) *
+                          int_multiple);
+
+  src_x_min_i = -int_multiple / 2;
+  src_y_min_i = -int_multiple / 2;
+
+  src_x_max_i = src_width  * int_multiple - int_multiple / 2;
+  src_y_max_i = src_height * int_multiple - int_multiple / 2;
+
+  gegl_parallel_distribute_area (
+    GEGL_RECTANGLE (0, 0, dest_width, dest_height), PIXELS_PER_THREAD,
+    [=] (const GeglRectangle *area)
+    {
+      guchar       *dest;
+      gint          src_space_cur_pos_x;
+      gint          src_space_cur_pos_y;
+      gint          src_space_cur_pos_x_i;
+      gint          src_space_cur_pos_y_i;
+      gint          src_space_row_start_x_i;
+      gint          src_space_row_start_y_i;
+      const guchar *src_walker;
+      const guchar *pixel_next;
+      const guchar *pixel_below;
+      const guchar *pixel_below_next;
+      gint          opposite_x, distance_from_true_x;
+      gint          opposite_y, distance_from_true_y;
+      gint          u, v;
+
+      dest = gimp_temp_buf_get_data (result) +
+             3 * (dest_width * area->y + area->x);
+
+      /* initialize current position in source space to the start position (tl)
+       * speed optimized, note conversion to int precision
+       */
+      src_space_row_start_x_i = (gint) (t_lx * int_multiple) +
+                                src_walk_vx_i * area->y      +
+                                src_walk_ux_i * area->x;
+      src_space_row_start_y_i = (gint) (t_ly * int_multiple) +
+                                src_walk_vy_i * area->y      +
+                                src_walk_uy_i * area->x;
+
+      for (v = 0; v < area->height; v++)
+        {
+          src_space_cur_pos_x_i = src_space_row_start_x_i;
+          src_space_cur_pos_y_i = src_space_row_start_y_i;
+
+          for (u = 0; u < area->width; u++)
+            {
+              if (src_space_cur_pos_x_i <  src_x_min_i ||
+                  src_space_cur_pos_x_i >= src_x_max_i ||
+                  src_space_cur_pos_y_i <  src_y_min_i ||
+                  src_space_cur_pos_y_i >= src_y_max_i)
+                  /* no corresponding pixel in source space */
+                {
+                  dest[0] = 0;
+                  dest[1] = 0;
+                  dest[2] = 0;
+                }
+              else /* reverse transformed point hits source pixel */
+                {
+                  src_space_cur_pos_x = src_space_cur_pos_x_i >> fraction_bits;
+                  src_space_cur_pos_y = src_space_cur_pos_y_i >> fraction_bits;
+
+                  src_walker = src                                  +
+                               3 * (src_space_cur_pos_y * src_width +
+                                    src_space_cur_pos_x);
+
+                  pixel_next       = src_walker + 3;
+                  pixel_below      = src_walker + 3 * src_width;
+                  pixel_below_next = pixel_below + 3;
+
+                  if (src_space_cur_pos_x < 0)
+                    {
+                      src_walker  = pixel_next;
+                      pixel_below = pixel_below_next;
+                    }
+                  else if (src_space_cur_pos_x >= src_width_minus_one)
+                    {
+                      pixel_next       = src_walker;
+                      pixel_below_next = pixel_below;
+                    }
+
+                  if (src_space_cur_pos_y < 0)
+                    {
+                      src_walker = pixel_below;
+                      pixel_next = pixel_below_next;
+                    }
+                  else if (src_space_cur_pos_y >= src_height_minus_one)
+                    {
+                      pixel_below      = src_walker;
+                      pixel_below_next = pixel_next;
+                    }
+
+                  distance_from_true_x = src_space_cur_pos_x_i & fraction_bitmask;
+                  distance_from_true_y = src_space_cur_pos_y_i & fraction_bitmask;
+                  opposite_x =  int_multiple - distance_from_true_x;
+                  opposite_y =  int_multiple - distance_from_true_y;
+
+                  dest[0] = ((src_walker[0] * opposite_x +
+                              pixel_next[0] * distance_from_true_x) * opposite_y +
+                             (pixel_below[0] * opposite_x +
+                              pixel_below_next[0] *distance_from_true_x) * distance_from_true_y
+                            ) >> recovery_bits;
+
+                  dest[1] = ((src_walker[1] * opposite_x +
+                              pixel_next[1] * distance_from_true_x) * opposite_y +
+                             (pixel_below[1] * opposite_x +
+                              pixel_below_next[1] *distance_from_true_x) * distance_from_true_y
+                            ) >> recovery_bits;
+
+                  dest[2] = ((src_walker[2] * opposite_x +
+                              pixel_next[2] * distance_from_true_x) * opposite_y +
+                             (pixel_below[2] * opposite_x +
+                              pixel_below_next[2] *distance_from_true_x) * distance_from_true_y
+                            ) >> recovery_bits;
+                }
+
+              src_space_cur_pos_x_i += src_walk_ux_i;
+              src_space_cur_pos_y_i += src_walk_uy_i;
+
+              dest += 3;
+            } /* end for x */
+
+          src_space_row_start_x_i += src_walk_vx_i;
+          src_space_row_start_y_i += src_walk_vy_i;
+
+          dest += 3 * (dest_width - area->width);
+        } /* end for y */
+    });
+
+  gimp_brush_transform_blur (result, blur_radius);
+
+  return result;
+}
+
+void
+gimp_brush_transform_get_scale (gdouble  scale,
+                                gdouble  aspect_ratio,
+                                gdouble *scale_x,
+                                gdouble *scale_y)
+{
+  if (aspect_ratio < 0.0)
+    {
+      *scale_x = scale * (1.0 + (aspect_ratio / 20.0));
+      *scale_y = scale;
+    }
+  else
+    {
+      *scale_x = scale;
+      *scale_y = scale * (1.0 - (aspect_ratio / 20.0));
+    }
+}
+
+void
+gimp_brush_transform_matrix (gdouble      width,
+                             gdouble      height,
+                             gdouble      scale_x,
+                             gdouble      scale_y,
+                             gdouble      angle,
+                             gboolean     reflect,
+                             GimpMatrix3 *matrix)
+{
+  const gdouble center_x = width  / 2;
+  const gdouble center_y = height / 2;
+
+  gimp_matrix3_identity (matrix);
+  gimp_matrix3_scale (matrix, scale_x, scale_y);
+  gimp_matrix3_translate (matrix, - center_x * scale_x, - center_y * scale_y);
+  gimp_matrix3_rotate (matrix, -2 * G_PI * angle);
+  if (reflect)
+    gimp_matrix3_scale (matrix, -1.0, 1.0);
+  gimp_matrix3_translate (matrix, center_x * scale_x, center_y * scale_y);
+}
+
+/*  private functions  */
+
+static void
+gimp_brush_transform_bounding_box (const GimpTempBuf *temp_buf,
+                                   const GimpMatrix3 *matrix,
+                                   gint              *x,
+                                   gint              *y,
+                                   gint              *width,
+                                   gint              *height)
+{
+  const gdouble  w = gimp_temp_buf_get_width  (temp_buf);
+  const gdouble  h = gimp_temp_buf_get_height (temp_buf);
+  gdouble        x1, x2, x3, x4;
+  gdouble        y1, y2, y3, y4;
+
+  gimp_matrix3_transform_point (matrix, 0, 0, &x1, &y1);
+  gimp_matrix3_transform_point (matrix, w, 0, &x2, &y2);
+  gimp_matrix3_transform_point (matrix, 0, h, &x3, &y3);
+  gimp_matrix3_transform_point (matrix, w, h, &x4, &y4);
+
+  *x = (gint) ceil (MIN (MIN (x1, x2), MIN (x3, x4)) - 0.5);
+  *y = (gint) ceil (MIN (MIN (y1, y2), MIN (y3, y4)) - 0.5);
+
+  *width  = (gint) ceil (MAX (MAX (x1, x2), MAX (x3, x4)) - 0.5) - *x;
+  *height = (gint) ceil (MAX (MAX (y1, y2), MAX (y3, y4)) - 0.5) - *y;
+
+  /* Transform size can not be less than 1 px */
+  *width  = MAX (1, *width);
+  *height = MAX (1, *height);
+}
+
+/* Blurs the brush mask/pixmap, in place, using a convolution of the form:
+ *
+ *   12  11  10   9   8
+ *    7   6   5   4   3
+ *    2   1   0   1   2
+ *    3   4   5   6   7
+ *    8   9  10  11  12
+ *
+ * (i.e., an array, wrapped into a matrix, whose i-th element is
+ * `abs (i - a / 2)`, where `a` is the length of the array.)  `r` specifies the
+ * convolution kernel's radius.
+ */
+static void
+gimp_brush_transform_blur (GimpTempBuf *buf,
+                           gint         r)
+{
+  typedef struct
+  {
+    gint sum;
+    gint weighted_sum;
+    gint middle_sum;
+  } Sums;
+
+  const Babl *format       = gimp_temp_buf_get_format (buf);
+  gint        components   = babl_format_get_n_components (format);
+  gint        components_r = components * r;
+  gint        width        = gimp_temp_buf_get_width (buf);
+  gint        height       = gimp_temp_buf_get_height (buf);
+  gint        stride       = components * width;
+  gint        stride_r     = stride * r;
+  guchar     *data         = gimp_temp_buf_get_data (buf);
+  gint        rw           = MIN (r, width - 1);
+  gint        rh           = MIN (r, height - 1);
+  gfloat      n            = 2 * r + 1;
+  gfloat      n_r          = n * r;
+  gfloat      weight       = floor (n * n / 2) * (floor (n * n / 2) + 1);
+  gfloat      weight_inv   = 1 / weight;
+  Sums       *sums;
+
+  if (rw <= 0 || rh <= 0)
+    return;
+
+  sums = g_new (Sums, width * height * components);
+
+  gegl_parallel_distribute_range (
+    height, PIXELS_PER_THREAD / width,
+    [=] (gint y0, gint height)
+    {
+      gint          x;
+      gint          y;
+      gint          c;
+      const guchar *d;
+      Sums         *s;
+
+      d = data + y0 * stride;
+      s = sums + y0 * stride;
+
+      for (y = 0; y < height; y++)
+        {
+          const guchar *p;
+
+          struct
+          {
+            gint sum;
+            gint weighted_sum;
+            gint leading_sum;
+            gint leading_weighted_sum;
+          } acc[components];
+
+          memset (acc, 0, sizeof (acc));
+
+          p = d;
+
+          for (x = 0; x <= rw; x++)
+            {
+              for (c = 0; c < components; c++)
+                {
+                  acc[c].sum          +=      *p;
+                  acc[c].weighted_sum += -x * *p;
+
+                  p++;
+                }
+            }
+
+          for (x = 0; x < width; x++)
+            {
+              for (c = 0; c < components; c++)
+                {
+                  if (x > 0)
+                    {
+                      acc[c].weighted_sum         += acc[c].sum;
+                      acc[c].leading_weighted_sum += acc[c].leading_sum;
+
+                      if (x < width - r)
+                        {
+                          acc[c].sum              +=      d[components_r];
+                          acc[c].weighted_sum     += -r * d[components_r];
+                        }
+                    }
+
+                  acc[c].leading_sum += d[0];
+
+                  s->sum          = acc[c].sum;
+                  s->weighted_sum = acc[c].weighted_sum;
+                  s->middle_sum   = 2 * acc[c].leading_weighted_sum -
+                                    acc[c].weighted_sum;
+
+                  if (x >= r)
+                    {
+                      acc[c].sum                  -=     d[-components_r];
+                      acc[c].weighted_sum         -= r * d[-components_r];
+                      acc[c].leading_sum          -=     d[-components_r];
+                      acc[c].leading_weighted_sum -= r * d[-components_r];
+                    }
+
+                  d++;
+                  s++;
+                }
+            }
+        }
+    });
+
+  gegl_parallel_distribute_range (
+    width, PIXELS_PER_THREAD / height,
+    [=] (gint x0, gint width)
+    {
+      gint        x;
+      gint        y;
+      gint        c;
+      guchar     *d0;
+      const Sums *s0;
+      guchar     *d;
+      const Sums *s;
+
+      d0 = data + x0 * components;
+      s0 = sums + x0 * components;
+
+      for (x = 0; x < width; x++)
+        {
+          const Sums *p;
+          gfloat      n_y;
+
+          struct
+          {
+            gfloat weighted_sum;
+            gint   leading_sum;
+            gint   trailing_sum;
+          } acc[components];
+
+          memset (acc, 0, sizeof (acc));
+
+          d = d0 + components * x;
+          s = s0 + components * x;
+
+          p = s + stride;
+
+          for (y = 1, n_y = n; y <= rh; y++, n_y += n)
+            {
+              for (c = 0; c < components; c++)
+                {
+                  acc[c].weighted_sum += n_y * p->sum - p->weighted_sum;
+                  acc[c].trailing_sum += p->sum;
+
+                  p++;
+                }
+
+              p += stride - components;
+            }
+
+          for (y = 0; y < height; y++)
+            {
+              for (c = 0; c < components; c++)
+                {
+                  if (y > 0)
+                    {
+                      acc[c].weighted_sum += s->weighted_sum          +
+                                             n * (acc[c].leading_sum  -
+                                                  acc[c].trailing_sum);
+                      acc[c].trailing_sum -= s->sum;
+
+                      if (y < height - r)
+                        {
+                          acc[c].weighted_sum += n_r * s[stride_r].sum -
+                                                 s[stride_r].weighted_sum;
+                          acc[c].trailing_sum += s[stride_r].sum;
+                        }
+                    }
+
+                  acc[c].leading_sum  += s->sum;
+
+                  *d = (acc[c].weighted_sum + s->middle_sum) * weight_inv + 0.5f;
+
+                  acc[c].weighted_sum += s->weighted_sum;
+
+                  if (y >= r)
+                    {
+                      acc[c].weighted_sum -= n_r * s[-stride_r].sum +
+                                             s[-stride_r].weighted_sum;
+                      acc[c].leading_sum  -= s[-stride_r].sum;
+                    }
+
+                  d++;
+                  s++;
+                }
+
+              d += stride - components;
+              s += stride - components;
+            }
+        }
+    });
+
+  g_free (sums);
+}
+
+static gint
+gimp_brush_transform_blur_radius (gint    height,
+                                  gint    width,
+                                  gdouble hardness)
+{
+  return floor ((1.0 - hardness) * (sqrt (0.5) - 0.5) * MIN (width, height));
+}
+
+static void
+gimp_brush_transform_adjust_hardness_matrix (gdouble      width,
+                                             gdouble      height,
+                                             gdouble      blur_radius,
+                                             GimpMatrix3 *matrix)
+{
+  gdouble scale;
+
+  if (blur_radius == 0.0)
+    return;
+
+  scale = (MIN (width, height) - 2.0 * blur_radius) / MIN (width, height);
+
+  gimp_matrix3_scale (matrix, scale, scale);
+  gimp_matrix3_translate (matrix,
+                          (1.0 - scale) * width  / 2.0,
+                          (1.0 - scale) * height / 2.0);
+}
+
+} /* extern "C" */
diff --git a/app/core/gimpbrush-transform.h b/app/core/gimpbrush-transform.h
new file mode 100644
index 0000000..5f7cbcb
--- /dev/null
+++ b/app/core/gimpbrush-transform.h
@@ -0,0 +1,59 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpbrush-transform.h
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_BRUSH_TRANSFORM_H__
+#define __GIMP_BRUSH_TRANSFORM_H__
+
+
+/*  virtual functions of GimpBrush, don't call directly  */
+
+void          gimp_brush_real_transform_size   (GimpBrush   *brush,
+                                                gdouble      scale,
+                                                gdouble      aspect_ratio,
+                                                gdouble      angle,
+                                                gboolean     reflect,
+                                                gint        *scaled_width,
+                                                gint        *scaled_height);
+GimpTempBuf * gimp_brush_real_transform_mask   (GimpBrush   *brush,
+                                                gdouble      scale,
+                                                gdouble      aspect_ratio,
+                                                gdouble      angle,
+                                                gboolean     reflect,
+                                                gdouble      hardness);
+GimpTempBuf * gimp_brush_real_transform_pixmap (GimpBrush   *brush,
+                                                gdouble      scale,
+                                                gdouble      aspect_ratio,
+                                                gdouble      angle,
+                                                gboolean     reflect,
+                                                gdouble      hardness);
+
+void          gimp_brush_transform_get_scale   (gdouble      scale,
+                                                gdouble      aspect_ratio,
+                                                gdouble     *scale_x,
+                                                gdouble     *scale_y);
+void          gimp_brush_transform_matrix      (gdouble      width,
+                                                gdouble      height,
+                                                gdouble      scale_x,
+                                                gdouble      scale_y,
+                                                gdouble      angle,
+                                                gboolean     reflect,
+                                                GimpMatrix3 *matrix);
+
+
+#endif  /*  __GIMP_BRUSH_TRANSFORM_H__  */
diff --git a/app/core/gimpbrush.c b/app/core/gimpbrush.c
new file mode 100644
index 0000000..8e15115
--- /dev/null
+++ b/app/core/gimpbrush.c
@@ -0,0 +1,942 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <cairo.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpmath/gimpmath.h"
+
+#include "core-types.h"
+
+#include "gimpbezierdesc.h"
+#include "gimpbrush.h"
+#include "gimpbrush-boundary.h"
+#include "gimpbrush-load.h"
+#include "gimpbrush-mipmap.h"
+#include "gimpbrush-private.h"
+#include "gimpbrush-save.h"
+#include "gimpbrush-transform.h"
+#include "gimpbrushcache.h"
+#include "gimpbrushgenerated.h"
+#include "gimpbrushpipe.h"
+#include "gimpmarshal.h"
+#include "gimptagged.h"
+#include "gimptempbuf.h"
+
+#include "gimp-intl.h"
+
+
+enum
+{
+  SPACING_CHANGED,
+  LAST_SIGNAL
+};
+
+enum
+{
+  PROP_0,
+  PROP_SPACING
+};
+
+
+static void          gimp_brush_tagged_iface_init     (GimpTaggedInterface  *iface);
+
+static void          gimp_brush_finalize              (GObject              *object);
+static void          gimp_brush_set_property          (GObject              *object,
+                                                       guint                 property_id,
+                                                       const GValue         *value,
+                                                       GParamSpec           *pspec);
+static void          gimp_brush_get_property          (GObject              *object,
+                                                       guint                 property_id,
+                                                       GValue               *value,
+                                                       GParamSpec           *pspec);
+
+static gint64        gimp_brush_get_memsize           (GimpObject           *object,
+                                                       gint64               *gui_size);
+
+static gboolean      gimp_brush_get_size              (GimpViewable         *viewable,
+                                                       gint                 *width,
+                                                       gint                 *height);
+static GimpTempBuf * gimp_brush_get_new_preview       (GimpViewable         *viewable,
+                                                       GimpContext          *context,
+                                                       gint                  width,
+                                                       gint                  height);
+static gchar       * gimp_brush_get_description       (GimpViewable         *viewable,
+                                                       gchar               **tooltip);
+
+static void          gimp_brush_dirty                 (GimpData             *data);
+static const gchar * gimp_brush_get_extension         (GimpData             *data);
+static void          gimp_brush_copy                  (GimpData             *data,
+                                                       GimpData             *src_data);
+
+static void          gimp_brush_real_begin_use        (GimpBrush            *brush);
+static void          gimp_brush_real_end_use          (GimpBrush            *brush);
+static GimpBrush   * gimp_brush_real_select_brush     (GimpBrush            *brush,
+                                                       const GimpCoords     *last_coords,
+                                                       const GimpCoords     *current_coords);
+static gboolean      gimp_brush_real_want_null_motion (GimpBrush            *brush,
+                                                       const GimpCoords     *last_coords,
+                                                       const GimpCoords     *current_coords);
+
+static gchar       * gimp_brush_get_checksum          (GimpTagged           *tagged);
+
+
+G_DEFINE_TYPE_WITH_CODE (GimpBrush, gimp_brush, GIMP_TYPE_DATA,
+                         G_ADD_PRIVATE (GimpBrush)
+                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_TAGGED,
+                                                gimp_brush_tagged_iface_init))
+
+#define parent_class gimp_brush_parent_class
+
+static guint brush_signals[LAST_SIGNAL] = { 0 };
+
+
+static void
+gimp_brush_class_init (GimpBrushClass *klass)
+{
+  GObjectClass      *object_class      = G_OBJECT_CLASS (klass);
+  GimpObjectClass   *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+  GimpViewableClass *viewable_class    = GIMP_VIEWABLE_CLASS (klass);
+  GimpDataClass     *data_class        = GIMP_DATA_CLASS (klass);
+
+  brush_signals[SPACING_CHANGED] =
+    g_signal_new ("spacing-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpBrushClass, spacing_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  object_class->finalize            = gimp_brush_finalize;
+  object_class->get_property        = gimp_brush_get_property;
+  object_class->set_property        = gimp_brush_set_property;
+
+  gimp_object_class->get_memsize    = gimp_brush_get_memsize;
+
+  viewable_class->default_icon_name = "gimp-tool-paintbrush";
+  viewable_class->get_size          = gimp_brush_get_size;
+  viewable_class->get_new_preview   = gimp_brush_get_new_preview;
+  viewable_class->get_description   = gimp_brush_get_description;
+
+  data_class->dirty                 = gimp_brush_dirty;
+  data_class->save                  = gimp_brush_save;
+  data_class->get_extension         = gimp_brush_get_extension;
+  data_class->copy                  = gimp_brush_copy;
+
+  klass->begin_use                  = gimp_brush_real_begin_use;
+  klass->end_use                    = gimp_brush_real_end_use;
+  klass->select_brush               = gimp_brush_real_select_brush;
+  klass->want_null_motion           = gimp_brush_real_want_null_motion;
+  klass->transform_size             = gimp_brush_real_transform_size;
+  klass->transform_mask             = gimp_brush_real_transform_mask;
+  klass->transform_pixmap           = gimp_brush_real_transform_pixmap;
+  klass->transform_boundary         = gimp_brush_real_transform_boundary;
+  klass->spacing_changed            = NULL;
+
+  g_object_class_install_property (object_class, PROP_SPACING,
+                                   g_param_spec_double ("spacing", NULL,
+                                                        _("Brush Spacing"),
+                                                        1.0, 5000.0, 20.0,
+                                                        GIMP_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT));
+}
+
+static void
+gimp_brush_tagged_iface_init (GimpTaggedInterface *iface)
+{
+  iface->get_checksum = gimp_brush_get_checksum;
+}
+
+static void
+gimp_brush_init (GimpBrush *brush)
+{
+  brush->priv = gimp_brush_get_instance_private (brush);
+
+  brush->priv->spacing  = 20;
+  brush->priv->x_axis.x = 15.0;
+  brush->priv->x_axis.y =  0.0;
+  brush->priv->y_axis.x =  0.0;
+  brush->priv->y_axis.y = 15.0;
+
+  brush->priv->blur_hardness = 1.0;
+}
+
+static void
+gimp_brush_finalize (GObject *object)
+{
+  GimpBrush *brush = GIMP_BRUSH (object);
+
+  g_clear_pointer (&brush->priv->mask,          gimp_temp_buf_unref);
+  g_clear_pointer (&brush->priv->pixmap,        gimp_temp_buf_unref);
+  g_clear_pointer (&brush->priv->blurred_mask,   gimp_temp_buf_unref);
+  g_clear_pointer (&brush->priv->blurred_pixmap, gimp_temp_buf_unref);
+
+  gimp_brush_mipmap_clear (brush);
+
+  g_clear_object (&brush->priv->mask_cache);
+  g_clear_object (&brush->priv->pixmap_cache);
+  g_clear_object (&brush->priv->boundary_cache);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gimp_brush_set_property (GObject      *object,
+                         guint         property_id,
+                         const GValue *value,
+                         GParamSpec   *pspec)
+{
+  GimpBrush *brush = GIMP_BRUSH (object);
+
+  switch (property_id)
+    {
+    case PROP_SPACING:
+      gimp_brush_set_spacing (brush, g_value_get_double (value));
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_brush_get_property (GObject    *object,
+                         guint       property_id,
+                         GValue     *value,
+                         GParamSpec *pspec)
+{
+  GimpBrush *brush = GIMP_BRUSH (object);
+
+  switch (property_id)
+    {
+    case PROP_SPACING:
+      g_value_set_double (value, gimp_brush_get_spacing (brush));
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static gint64
+gimp_brush_get_memsize (GimpObject *object,
+                        gint64     *gui_size)
+{
+  GimpBrush *brush   = GIMP_BRUSH (object);
+  gint64     memsize = 0;
+
+  memsize += gimp_temp_buf_get_memsize (brush->priv->mask);
+  memsize += gimp_temp_buf_get_memsize (brush->priv->pixmap);
+
+  memsize += gimp_brush_mipmap_get_memsize (brush);
+
+  return memsize + GIMP_OBJECT_CLASS (parent_class)->get_memsize (object,
+                                                                  gui_size);
+}
+
+static gboolean
+gimp_brush_get_size (GimpViewable *viewable,
+                     gint         *width,
+                     gint         *height)
+{
+  GimpBrush *brush = GIMP_BRUSH (viewable);
+
+  *width  = gimp_temp_buf_get_width  (brush->priv->mask);
+  *height = gimp_temp_buf_get_height (brush->priv->mask);
+
+  return TRUE;
+}
+
+static GimpTempBuf *
+gimp_brush_get_new_preview (GimpViewable *viewable,
+                            GimpContext  *context,
+                            gint          width,
+                            gint          height)
+{
+  GimpBrush         *brush       = GIMP_BRUSH (viewable);
+  const GimpTempBuf *mask_buf    = brush->priv->mask;
+  const GimpTempBuf *pixmap_buf  = brush->priv->pixmap;
+  GimpTempBuf       *return_buf  = NULL;
+  gint               mask_width;
+  gint               mask_height;
+  guchar            *mask_data;
+  guchar            *mask;
+  guchar            *buf;
+  gint               x, y;
+  gboolean           scaled = FALSE;
+
+  mask_width  = gimp_temp_buf_get_width  (mask_buf);
+  mask_height = gimp_temp_buf_get_height (mask_buf);
+
+  if (mask_width > width || mask_height > height)
+    {
+      gdouble ratio_x = (gdouble) width  / (gdouble) mask_width;
+      gdouble ratio_y = (gdouble) height / (gdouble) mask_height;
+      gdouble scale   = MIN (ratio_x, ratio_y);
+
+      if (scale != 1.0)
+        {
+          gimp_brush_begin_use (brush);
+
+          if (GIMP_IS_BRUSH_GENERATED (brush))
+            {
+               GimpBrushGenerated *gen_brush = GIMP_BRUSH_GENERATED (brush);
+
+               mask_buf = gimp_brush_transform_mask (brush, scale,
+                                                     (gimp_brush_generated_get_aspect_ratio (gen_brush) - 1.0) * 20.0 / 19.0,
+                                                     gimp_brush_generated_get_angle (gen_brush) / 360.0,
+                                                     FALSE,
+                                                     gimp_brush_generated_get_hardness (gen_brush));
+            }
+          else
+            mask_buf = gimp_brush_transform_mask (brush, scale,
+                                                  0.0, 0.0, FALSE, 1.0);
+
+          if (! mask_buf)
+            {
+              mask_buf = gimp_temp_buf_new (1, 1, babl_format ("Y u8"));
+              gimp_temp_buf_data_clear ((GimpTempBuf *) mask_buf);
+            }
+          else
+            {
+              gimp_temp_buf_ref ((GimpTempBuf *) mask_buf);
+            }
+
+          if (pixmap_buf)
+            pixmap_buf = gimp_brush_transform_pixmap (brush, scale,
+                                                      0.0, 0.0, FALSE, 1.0);
+
+          mask_width  = gimp_temp_buf_get_width  (mask_buf);
+          mask_height = gimp_temp_buf_get_height (mask_buf);
+
+          scaled = TRUE;
+        }
+    }
+
+  return_buf = gimp_temp_buf_new (mask_width, mask_height,
+                                  babl_format ("R'G'B'A u8"));
+
+  mask = mask_data = gimp_temp_buf_lock (mask_buf, babl_format ("Y u8"),
+                                         GEGL_ACCESS_READ);
+  buf  = gimp_temp_buf_get_data (return_buf);
+
+  if (pixmap_buf)
+    {
+      guchar *pixmap_data;
+      guchar *pixmap;
+
+      pixmap = pixmap_data = gimp_temp_buf_lock (pixmap_buf,
+                                                 babl_format ("R'G'B' u8"),
+                                                 GEGL_ACCESS_READ);
+
+      for (y = 0; y < mask_height; y++)
+        {
+          for (x = 0; x < mask_width ; x++)
+            {
+              *buf++ = *pixmap++;
+              *buf++ = *pixmap++;
+              *buf++ = *pixmap++;
+              *buf++ = *mask++;
+            }
+        }
+
+      gimp_temp_buf_unlock (pixmap_buf, pixmap_data);
+    }
+  else
+    {
+      for (y = 0; y < mask_height; y++)
+        {
+          for (x = 0; x < mask_width ; x++)
+            {
+              *buf++ = 0;
+              *buf++ = 0;
+              *buf++ = 0;
+              *buf++ = *mask++;
+            }
+        }
+    }
+
+  gimp_temp_buf_unlock (mask_buf, mask_data);
+
+  if (scaled)
+    {
+      gimp_temp_buf_unref ((GimpTempBuf *) mask_buf);
+
+      gimp_brush_end_use (brush);
+    }
+
+  return return_buf;
+}
+
+static gchar *
+gimp_brush_get_description (GimpViewable  *viewable,
+                            gchar        **tooltip)
+{
+  GimpBrush *brush = GIMP_BRUSH (viewable);
+
+  return g_strdup_printf ("%s (%d × %d)",
+                          gimp_object_get_name (brush),
+                          gimp_temp_buf_get_width  (brush->priv->mask),
+                          gimp_temp_buf_get_height (brush->priv->mask));
+}
+
+static void
+gimp_brush_dirty (GimpData *data)
+{
+  GimpBrush *brush = GIMP_BRUSH (data);
+
+  if (brush->priv->mask_cache)
+    gimp_brush_cache_clear (brush->priv->mask_cache);
+
+  if (brush->priv->pixmap_cache)
+    gimp_brush_cache_clear (brush->priv->pixmap_cache);
+
+  if (brush->priv->boundary_cache)
+    gimp_brush_cache_clear (brush->priv->boundary_cache);
+
+  gimp_brush_mipmap_clear (brush);
+
+  g_clear_pointer (&brush->priv->blurred_mask,   gimp_temp_buf_unref);
+  g_clear_pointer (&brush->priv->blurred_pixmap, gimp_temp_buf_unref);
+
+  GIMP_DATA_CLASS (parent_class)->dirty (data);
+}
+
+static const gchar *
+gimp_brush_get_extension (GimpData *data)
+{
+  return GIMP_BRUSH_FILE_EXTENSION;
+}
+
+static void
+gimp_brush_copy (GimpData *data,
+                 GimpData *src_data)
+{
+  GimpBrush *brush     = GIMP_BRUSH (data);
+  GimpBrush *src_brush = GIMP_BRUSH (src_data);
+
+  g_clear_pointer (&brush->priv->mask, gimp_temp_buf_unref);
+  if (src_brush->priv->mask)
+    brush->priv->mask = gimp_temp_buf_copy (src_brush->priv->mask);
+
+  g_clear_pointer (&brush->priv->pixmap, gimp_temp_buf_unref);
+  if (src_brush->priv->pixmap)
+    brush->priv->pixmap = gimp_temp_buf_copy (src_brush->priv->pixmap);
+
+  brush->priv->spacing = src_brush->priv->spacing;
+  brush->priv->x_axis  = src_brush->priv->x_axis;
+  brush->priv->y_axis  = src_brush->priv->y_axis;
+
+  gimp_data_dirty (data);
+}
+
+static void
+gimp_brush_real_begin_use (GimpBrush *brush)
+{
+  brush->priv->mask_cache =
+    gimp_brush_cache_new ((GDestroyNotify) gimp_temp_buf_unref, 'M', 'm');
+
+  brush->priv->pixmap_cache =
+    gimp_brush_cache_new ((GDestroyNotify) gimp_temp_buf_unref, 'P', 'p');
+
+  brush->priv->boundary_cache =
+    gimp_brush_cache_new ((GDestroyNotify) gimp_bezier_desc_free, 'B', 'b');
+}
+
+static void
+gimp_brush_real_end_use (GimpBrush *brush)
+{
+  g_clear_object (&brush->priv->mask_cache);
+  g_clear_object (&brush->priv->pixmap_cache);
+  g_clear_object (&brush->priv->boundary_cache);
+
+  g_clear_pointer (&brush->priv->blurred_mask,   gimp_temp_buf_unref);
+  g_clear_pointer (&brush->priv->blurred_pixmap, gimp_temp_buf_unref);
+}
+
+static GimpBrush *
+gimp_brush_real_select_brush (GimpBrush        *brush,
+                              const GimpCoords *last_coords,
+                              const GimpCoords *current_coords)
+{
+  return brush;
+}
+
+static gboolean
+gimp_brush_real_want_null_motion (GimpBrush        *brush,
+                                  const GimpCoords *last_coords,
+                                  const GimpCoords *current_coords)
+{
+  return TRUE;
+}
+
+static gchar *
+gimp_brush_get_checksum (GimpTagged *tagged)
+{
+  GimpBrush *brush           = GIMP_BRUSH (tagged);
+  gchar     *checksum_string = NULL;
+
+  if (brush->priv->mask)
+    {
+      GChecksum *checksum = g_checksum_new (G_CHECKSUM_MD5);
+
+      g_checksum_update (checksum,
+                         gimp_temp_buf_get_data (brush->priv->mask),
+                         gimp_temp_buf_get_data_size (brush->priv->mask));
+      if (brush->priv->pixmap)
+        g_checksum_update (checksum,
+                           gimp_temp_buf_get_data (brush->priv->pixmap),
+                           gimp_temp_buf_get_data_size (brush->priv->pixmap));
+      g_checksum_update (checksum,
+                         (const guchar *) &brush->priv->spacing,
+                         sizeof (brush->priv->spacing));
+      g_checksum_update (checksum,
+                         (const guchar *) &brush->priv->x_axis,
+                         sizeof (brush->priv->x_axis));
+      g_checksum_update (checksum,
+                         (const guchar *) &brush->priv->y_axis,
+                         sizeof (brush->priv->y_axis));
+
+      checksum_string = g_strdup (g_checksum_get_string (checksum));
+
+      g_checksum_free (checksum);
+    }
+
+  return checksum_string;
+}
+
+/*  public functions  */
+
+GimpData *
+gimp_brush_new (GimpContext *context,
+                const gchar *name)
+{
+  g_return_val_if_fail (name != NULL, NULL);
+
+  return gimp_brush_generated_new (name,
+                                   GIMP_BRUSH_GENERATED_CIRCLE,
+                                   5.0, 2, 0.5, 1.0, 0.0);
+}
+
+GimpData *
+gimp_brush_get_standard (GimpContext *context)
+{
+  static GimpData *standard_brush = NULL;
+
+  if (! standard_brush)
+    {
+      standard_brush = gimp_brush_new (context, "Standard");
+
+      gimp_data_clean (standard_brush);
+      gimp_data_make_internal (standard_brush, "gimp-brush-standard");
+
+      g_object_add_weak_pointer (G_OBJECT (standard_brush),
+                                 (gpointer *) &standard_brush);
+    }
+
+  return standard_brush;
+}
+
+void
+gimp_brush_begin_use (GimpBrush *brush)
+{
+  g_return_if_fail (GIMP_IS_BRUSH (brush));
+
+  brush->priv->use_count++;
+
+  if (brush->priv->use_count == 1)
+    GIMP_BRUSH_GET_CLASS (brush)->begin_use (brush);
+}
+
+void
+gimp_brush_end_use (GimpBrush *brush)
+{
+  g_return_if_fail (GIMP_IS_BRUSH (brush));
+  g_return_if_fail (brush->priv->use_count > 0);
+
+  brush->priv->use_count--;
+
+  if (brush->priv->use_count == 0)
+    GIMP_BRUSH_GET_CLASS (brush)->end_use (brush);
+}
+
+GimpBrush *
+gimp_brush_select_brush (GimpBrush        *brush,
+                         const GimpCoords *last_coords,
+                         const GimpCoords *current_coords)
+{
+  g_return_val_if_fail (GIMP_IS_BRUSH (brush), NULL);
+  g_return_val_if_fail (last_coords != NULL, NULL);
+  g_return_val_if_fail (current_coords != NULL, NULL);
+
+  return GIMP_BRUSH_GET_CLASS (brush)->select_brush (brush,
+                                                     last_coords,
+                                                     current_coords);
+}
+
+gboolean
+gimp_brush_want_null_motion (GimpBrush        *brush,
+                             const GimpCoords *last_coords,
+                             const GimpCoords *current_coords)
+{
+  g_return_val_if_fail (GIMP_IS_BRUSH (brush), FALSE);
+  g_return_val_if_fail (last_coords != NULL, FALSE);
+  g_return_val_if_fail (current_coords != NULL, FALSE);
+
+  return GIMP_BRUSH_GET_CLASS (brush)->want_null_motion (brush,
+                                                         last_coords,
+                                                         current_coords);
+}
+
+void
+gimp_brush_transform_size (GimpBrush     *brush,
+                           gdouble        scale,
+                           gdouble        aspect_ratio,
+                           gdouble        angle,
+                           gboolean       reflect,
+                           gint          *width,
+                           gint          *height)
+{
+  g_return_if_fail (GIMP_IS_BRUSH (brush));
+  g_return_if_fail (scale > 0.0);
+  g_return_if_fail (width != NULL);
+  g_return_if_fail (height != NULL);
+
+  if (scale             == 1.0 &&
+      aspect_ratio      == 0.0 &&
+      fmod (angle, 0.5) == 0.0)
+    {
+      *width  = gimp_temp_buf_get_width  (brush->priv->mask);
+      *height = gimp_temp_buf_get_height (brush->priv->mask);
+
+      return;
+    }
+
+  GIMP_BRUSH_GET_CLASS (brush)->transform_size (brush,
+                                                scale, aspect_ratio, angle, reflect,
+                                                width, height);
+}
+
+const GimpTempBuf *
+gimp_brush_transform_mask (GimpBrush *brush,
+                           gdouble    scale,
+                           gdouble    aspect_ratio,
+                           gdouble    angle,
+                           gboolean   reflect,
+                           gdouble    hardness)
+{
+  const GimpTempBuf *mask;
+  gint               width;
+  gint               height;
+  gdouble            effective_hardness = hardness;
+
+  g_return_val_if_fail (GIMP_IS_BRUSH (brush), NULL);
+  g_return_val_if_fail (scale > 0.0, NULL);
+
+  gimp_brush_transform_size (brush,
+                             scale, aspect_ratio, angle, reflect,
+                             &width, &height);
+
+  mask = gimp_brush_cache_get (brush->priv->mask_cache,
+                               width, height,
+                               scale, aspect_ratio, angle, reflect, hardness);
+
+  if (! mask)
+    {
+#if 0
+      /* This code makes sure that brushes using blur for hardness
+       * (all of them but generated) are blurred once and no more.
+       * It also makes hardnes dynamics not work for these brushes.
+       * This is intentional. Confoliving for each stamp is too expensive.*/
+      if (! brush->priv->blurred_mask &&
+          ! GIMP_IS_BRUSH_GENERATED(brush) &&
+          ! GIMP_IS_BRUSH_PIPE(brush) && /*Can't cache pipes. Sanely anyway*/
+          hardness < 1.0)
+        {
+           brush->priv->blurred_mask = GIMP_BRUSH_GET_CLASS (brush)->transform_mask (brush,
+                                                             1.0,
+                                                             0.0,
+                                                             0.0,
+                                                             FALSE,
+                                                             hardness);
+           brush->priv->blur_hardness = hardness;
+        }
+
+      if (brush->priv->blurred_mask)
+        {
+          effective_hardness = 1.0; /*Hardness has already been applied*/
+        }
+#endif
+
+      mask = GIMP_BRUSH_GET_CLASS (brush)->transform_mask (brush,
+                                                           scale,
+                                                           aspect_ratio,
+                                                           angle,
+                                                           reflect,
+                                                           effective_hardness);
+
+      gimp_brush_cache_add (brush->priv->mask_cache,
+                            (gpointer) mask,
+                            width, height,
+                            scale, aspect_ratio, angle, reflect, effective_hardness);
+    }
+
+  return mask;
+}
+
+const GimpTempBuf *
+gimp_brush_transform_pixmap (GimpBrush *brush,
+                             gdouble    scale,
+                             gdouble    aspect_ratio,
+                             gdouble    angle,
+                             gboolean   reflect,
+                             gdouble    hardness)
+{
+  const GimpTempBuf *pixmap;
+  gint               width;
+  gint               height;
+  gdouble            effective_hardness = hardness;
+
+  g_return_val_if_fail (GIMP_IS_BRUSH (brush), NULL);
+  g_return_val_if_fail (brush->priv->pixmap != NULL, NULL);
+  g_return_val_if_fail (scale > 0.0, NULL);
+
+  gimp_brush_transform_size (brush,
+                             scale, aspect_ratio, angle, reflect,
+                             &width, &height);
+
+  pixmap = gimp_brush_cache_get (brush->priv->pixmap_cache,
+                                 width, height,
+                                 scale, aspect_ratio, angle, reflect, hardness);
+
+  if (! pixmap)
+    {
+#if 0
+     if (! brush->priv->blurred_pixmap &&
+         ! GIMP_IS_BRUSH_GENERATED(brush) &&
+         ! GIMP_IS_BRUSH_PIPE(brush) /*Can't cache pipes. Sanely anyway*/
+         && hardness < 1.0)
+      {
+         brush->priv->blurred_pixmap = GIMP_BRUSH_GET_CLASS (brush)->transform_pixmap (brush,
+                                                                  1.0,
+                                                                  0.0,
+                                                                  0.0,
+                                                                  FALSE,
+                                                                  hardness);
+         brush->priv->blur_hardness = hardness;
+       }
+
+      if (brush->priv->blurred_pixmap) {
+        effective_hardness = 1.0; /*Hardness has already been applied*/
+      }
+#endif
+
+      pixmap = GIMP_BRUSH_GET_CLASS (brush)->transform_pixmap (brush,
+                                                               scale,
+                                                               aspect_ratio,
+                                                               angle,
+                                                               reflect,
+                                                               effective_hardness);
+
+      gimp_brush_cache_add (brush->priv->pixmap_cache,
+                            (gpointer) pixmap,
+                            width, height,
+                            scale, aspect_ratio, angle, reflect, effective_hardness);
+    }
+
+  return pixmap;
+}
+
+const GimpBezierDesc *
+gimp_brush_transform_boundary (GimpBrush *brush,
+                               gdouble    scale,
+                               gdouble    aspect_ratio,
+                               gdouble    angle,
+                               gboolean   reflect,
+                               gdouble    hardness,
+                               gint      *width,
+                               gint      *height)
+{
+  const GimpBezierDesc *boundary;
+
+  g_return_val_if_fail (GIMP_IS_BRUSH (brush), NULL);
+  g_return_val_if_fail (scale > 0.0, NULL);
+  g_return_val_if_fail (width != NULL, NULL);
+  g_return_val_if_fail (height != NULL, NULL);
+
+  gimp_brush_transform_size (brush,
+                             scale, aspect_ratio, angle, reflect,
+                             width, height);
+
+  boundary = gimp_brush_cache_get (brush->priv->boundary_cache,
+                                   *width, *height,
+                                   scale, aspect_ratio, angle, reflect, hardness);
+
+  if (! boundary)
+    {
+      boundary = GIMP_BRUSH_GET_CLASS (brush)->transform_boundary (brush,
+                                                                   scale,
+                                                                   aspect_ratio,
+                                                                   angle,
+                                                                   reflect,
+                                                                   hardness,
+                                                                   width,
+                                                                   height);
+
+      /*  while the brush mask is always at least 1x1 pixels, its
+       *  outline can correctly be NULL
+       *
+       *  FIXME: make the cache handle NULL things when it is
+       *         properly implemented
+       */
+      if (boundary)
+        gimp_brush_cache_add (brush->priv->boundary_cache,
+                              (gpointer) boundary,
+                              *width, *height,
+                              scale, aspect_ratio, angle, reflect, hardness);
+    }
+
+  return boundary;
+}
+
+GimpTempBuf *
+gimp_brush_get_mask (GimpBrush *brush)
+{
+  g_return_val_if_fail (brush != NULL, NULL);
+  g_return_val_if_fail (GIMP_IS_BRUSH (brush), NULL);
+
+  if (brush->priv->blurred_mask)
+    {
+      return brush->priv->blurred_mask;
+    }
+  return brush->priv->mask;
+}
+
+GimpTempBuf *
+gimp_brush_get_pixmap (GimpBrush *brush)
+{
+  g_return_val_if_fail (brush != NULL, NULL);
+  g_return_val_if_fail (GIMP_IS_BRUSH (brush), NULL);
+
+  if(brush->priv->blurred_pixmap)
+    {
+      return brush->priv->blurred_pixmap;
+    }
+  return brush->priv->pixmap;
+}
+
+void
+gimp_brush_flush_blur_caches (GimpBrush *brush)
+{
+#if 0
+  g_clear_pointer (&brush->priv->blurred_mask,   gimp_temp_buf_unref);
+  g_clear_pointer (&brush->priv->blurred_pixmap, gimp_temp_buf_unref);
+
+  if (brush->priv->mask_cache)
+    gimp_brush_cache_clear (brush->priv->mask_cache);
+
+  if (brush->priv->pixmap_cache)
+    gimp_brush_cache_clear (brush->priv->pixmap_cache);
+
+  if (brush->priv->boundary_cache)
+    gimp_brush_cache_clear (brush->priv->boundary_cache);
+#endif
+}
+
+gdouble
+gimp_brush_get_blur_hardness (GimpBrush *brush)
+{
+  g_return_val_if_fail (GIMP_IS_BRUSH (brush), 0);
+
+  return brush->priv->blur_hardness;
+}
+
+gint
+gimp_brush_get_width (GimpBrush *brush)
+{
+  g_return_val_if_fail (GIMP_IS_BRUSH (brush), 0);
+
+  if (brush->priv->blurred_mask)
+    return gimp_temp_buf_get_width (brush->priv->blurred_mask);
+
+  if (brush->priv->blurred_pixmap)
+    return gimp_temp_buf_get_width (brush->priv->blurred_pixmap);
+
+  return gimp_temp_buf_get_width (brush->priv->mask);
+}
+
+gint
+gimp_brush_get_height (GimpBrush *brush)
+{
+  g_return_val_if_fail (GIMP_IS_BRUSH (brush), 0);
+
+  if (brush->priv->blurred_mask)
+    return gimp_temp_buf_get_height (brush->priv->blurred_mask);
+
+  if (brush->priv->blurred_pixmap)
+    return gimp_temp_buf_get_height (brush->priv->blurred_pixmap);
+
+  return gimp_temp_buf_get_height (brush->priv->mask);
+}
+
+gint
+gimp_brush_get_spacing (GimpBrush *brush)
+{
+  g_return_val_if_fail (GIMP_IS_BRUSH (brush), 0);
+
+  return brush->priv->spacing;
+}
+
+void
+gimp_brush_set_spacing (GimpBrush *brush,
+                        gint       spacing)
+{
+  g_return_if_fail (GIMP_IS_BRUSH (brush));
+
+  if (brush->priv->spacing != spacing)
+    {
+      brush->priv->spacing = spacing;
+
+      g_signal_emit (brush, brush_signals[SPACING_CHANGED], 0);
+      g_object_notify (G_OBJECT (brush), "spacing");
+    }
+}
+
+static const GimpVector2 fail = { 0.0, 0.0 };
+
+GimpVector2
+gimp_brush_get_x_axis (GimpBrush *brush)
+{
+  g_return_val_if_fail (GIMP_IS_BRUSH (brush), fail);
+
+  return brush->priv->x_axis;
+}
+
+GimpVector2
+gimp_brush_get_y_axis (GimpBrush *brush)
+{
+  g_return_val_if_fail (GIMP_IS_BRUSH (brush), fail);
+
+  return brush->priv->y_axis;
+}
diff --git a/app/core/gimpbrush.h b/app/core/gimpbrush.h
new file mode 100644
index 0000000..b5735f0
--- /dev/null
+++ b/app/core/gimpbrush.h
@@ -0,0 +1,152 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_BRUSH_H__
+#define __GIMP_BRUSH_H__
+
+
+#include "gimpdata.h"
+
+
+#define GIMP_TYPE_BRUSH            (gimp_brush_get_type ())
+#define GIMP_BRUSH(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_BRUSH, GimpBrush))
+#define GIMP_BRUSH_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_BRUSH, GimpBrushClass))
+#define GIMP_IS_BRUSH(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_BRUSH))
+#define GIMP_IS_BRUSH_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_BRUSH))
+#define GIMP_BRUSH_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_BRUSH, GimpBrushClass))
+
+
+typedef struct _GimpBrushPrivate GimpBrushPrivate;
+typedef struct _GimpBrushClass   GimpBrushClass;
+
+struct _GimpBrush
+{
+  GimpData          parent_instance;
+
+  GimpBrushPrivate *priv;
+};
+
+struct _GimpBrushClass
+{
+  GimpDataClass  parent_class;
+
+  /*  virtual functions  */
+  void             (* begin_use)          (GimpBrush        *brush);
+  void             (* end_use)            (GimpBrush        *brush);
+  GimpBrush      * (* select_brush)       (GimpBrush        *brush,
+                                           const GimpCoords *last_coords,
+                                           const GimpCoords *current_coords);
+  gboolean         (* want_null_motion)   (GimpBrush        *brush,
+                                           const GimpCoords *last_coords,
+                                           const GimpCoords *current_coords);
+  void             (* transform_size)     (GimpBrush        *brush,
+                                           gdouble           scale,
+                                           gdouble           aspect_ratio,
+                                           gdouble           angle,
+                                           gboolean          reflect,
+                                           gint             *width,
+                                           gint             *height);
+  GimpTempBuf    * (* transform_mask)     (GimpBrush        *brush,
+                                           gdouble           scale,
+                                           gdouble           aspect_ratio,
+                                           gdouble           angle,
+                                           gboolean          reflect,
+                                           gdouble           hardness);
+  GimpTempBuf    * (* transform_pixmap)   (GimpBrush        *brush,
+                                           gdouble           scale,
+                                           gdouble           aspect_ratio,
+                                           gdouble           angle,
+                                           gboolean          reflect,
+                                           gdouble           hardness);
+  GimpBezierDesc * (* transform_boundary) (GimpBrush        *brush,
+                                           gdouble           scale,
+                                           gdouble           aspect_ratio,
+                                           gdouble           angle,
+                                           gboolean          reflect,
+                                           gdouble           hardness,
+                                           gint             *width,
+                                           gint             *height);
+
+  /*  signals  */
+  void             (* spacing_changed)    (GimpBrush        *brush);
+};
+
+
+GType                  gimp_brush_get_type           (void) G_GNUC_CONST;
+
+GimpData             * gimp_brush_new                (GimpContext      *context,
+                                                      const gchar      *name);
+GimpData             * gimp_brush_get_standard       (GimpContext      *context);
+
+void                   gimp_brush_begin_use          (GimpBrush        *brush);
+void                   gimp_brush_end_use            (GimpBrush        *brush);
+
+GimpBrush            * gimp_brush_select_brush       (GimpBrush        *brush,
+                                                      const GimpCoords *last_coords,
+                                                      const GimpCoords *current_coords);
+gboolean               gimp_brush_want_null_motion   (GimpBrush        *brush,
+                                                      const GimpCoords *last_coords,
+                                                      const GimpCoords *current_coords);
+
+/* Gets width and height of a transformed mask of the brush, for
+ * provided parameters.
+ */
+void                   gimp_brush_transform_size     (GimpBrush        *brush,
+                                                      gdouble           scale,
+                                                      gdouble           aspect_ratio,
+                                                      gdouble           angle,
+                                                      gboolean          reflect,
+                                                      gint             *width,
+                                                      gint             *height);
+const GimpTempBuf    * gimp_brush_transform_mask     (GimpBrush        *brush,
+                                                      gdouble           scale,
+                                                      gdouble           aspect_ratio,
+                                                      gdouble           angle,
+                                                      gboolean          reflect,
+                                                      gdouble           hardness);
+const GimpTempBuf    * gimp_brush_transform_pixmap   (GimpBrush        *brush,
+                                                      gdouble           scale,
+                                                      gdouble           aspect_ratio,
+                                                      gdouble           angle,
+                                                      gboolean          reflect,
+                                                      gdouble           hardness);
+const GimpBezierDesc * gimp_brush_transform_boundary (GimpBrush        *brush,
+                                                      gdouble           scale,
+                                                      gdouble           aspect_ratio,
+                                                      gdouble           angle,
+                                                      gboolean          reflect,
+                                                      gdouble           hardness,
+                                                      gint             *width,
+                                                      gint             *height);
+
+GimpTempBuf          * gimp_brush_get_mask           (GimpBrush        *brush);
+GimpTempBuf          * gimp_brush_get_pixmap         (GimpBrush        *brush);
+
+gint                   gimp_brush_get_width          (GimpBrush        *brush);
+gint                   gimp_brush_get_height         (GimpBrush        *brush);
+
+gint                   gimp_brush_get_spacing        (GimpBrush        *brush);
+void                   gimp_brush_set_spacing        (GimpBrush        *brush,
+                                                      gint              spacing);
+
+GimpVector2            gimp_brush_get_x_axis         (GimpBrush        *brush);
+GimpVector2            gimp_brush_get_y_axis         (GimpBrush        *brush);
+
+void                   gimp_brush_flush_blur_caches  (GimpBrush        *brush);
+gdouble                gimp_brush_get_blur_hardness  (GimpBrush        *brush);
+
+#endif /* __GIMP_BRUSH_H__ */
diff --git a/app/core/gimpbrushcache.c b/app/core/gimpbrushcache.c
new file mode 100644
index 0000000..07ad008
--- /dev/null
+++ b/app/core/gimpbrushcache.c
@@ -0,0 +1,299 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpbrushcache.c
+ * Copyright (C) 2011 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gimpbrushcache.h"
+
+#include "gimp-log.h"
+#include "gimp-intl.h"
+
+
+#define MAX_CACHED_DATA 20
+
+
+enum
+{
+  PROP_0,
+  PROP_DATA_DESTROY
+};
+
+
+typedef struct _GimpBrushCacheUnit GimpBrushCacheUnit;
+
+struct _GimpBrushCacheUnit
+{
+  gpointer data;
+
+  gint     width;
+  gint     height;
+  gdouble  scale;
+  gdouble  aspect_ratio;
+  gdouble  angle;
+  gboolean reflect;
+  gdouble  hardness;
+};
+
+
+static void   gimp_brush_cache_constructed  (GObject      *object);
+static void   gimp_brush_cache_finalize     (GObject      *object);
+static void   gimp_brush_cache_set_property (GObject      *object,
+                                             guint         property_id,
+                                             const GValue *value,
+                                             GParamSpec   *pspec);
+static void   gimp_brush_cache_get_property (GObject      *object,
+                                             guint         property_id,
+                                             GValue       *value,
+                                             GParamSpec   *pspec);
+
+
+G_DEFINE_TYPE (GimpBrushCache, gimp_brush_cache, GIMP_TYPE_OBJECT)
+
+#define parent_class gimp_brush_cache_parent_class
+
+
+static void
+gimp_brush_cache_class_init (GimpBrushCacheClass *klass)
+{
+  GObjectClass  *object_class = G_OBJECT_CLASS (klass);
+
+  object_class->constructed  = gimp_brush_cache_constructed;
+  object_class->finalize     = gimp_brush_cache_finalize;
+  object_class->set_property = gimp_brush_cache_set_property;
+  object_class->get_property = gimp_brush_cache_get_property;
+
+  g_object_class_install_property (object_class, PROP_DATA_DESTROY,
+                                   g_param_spec_pointer ("data-destroy",
+                                                         NULL, NULL,
+                                                         GIMP_PARAM_READWRITE |
+                                                         G_PARAM_CONSTRUCT_ONLY));
+}
+
+static void
+gimp_brush_cache_init (GimpBrushCache *brush)
+{
+}
+
+static void
+gimp_brush_cache_constructed (GObject *object)
+{
+  GimpBrushCache *cache = GIMP_BRUSH_CACHE (object);
+
+  G_OBJECT_CLASS (parent_class)->constructed (object);
+
+  gimp_assert (cache->data_destroy != NULL);
+}
+
+static void
+gimp_brush_cache_finalize (GObject *object)
+{
+  GimpBrushCache *cache = GIMP_BRUSH_CACHE (object);
+
+  gimp_brush_cache_clear (cache);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gimp_brush_cache_set_property (GObject      *object,
+                               guint         property_id,
+                               const GValue *value,
+                               GParamSpec   *pspec)
+{
+  GimpBrushCache *cache = GIMP_BRUSH_CACHE (object);
+
+  switch (property_id)
+    {
+    case PROP_DATA_DESTROY:
+      cache->data_destroy = g_value_get_pointer (value);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_brush_cache_get_property (GObject    *object,
+                               guint       property_id,
+                               GValue     *value,
+                               GParamSpec *pspec)
+{
+  GimpBrushCache *cache = GIMP_BRUSH_CACHE (object);
+
+  switch (property_id)
+    {
+    case PROP_DATA_DESTROY:
+      g_value_set_pointer (value, cache->data_destroy);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+
+/*  public functions  */
+
+GimpBrushCache *
+gimp_brush_cache_new (GDestroyNotify  data_destroy,
+                      gchar           debug_hit,
+                      gchar           debug_miss)
+{
+  GimpBrushCache *cache;
+
+  g_return_val_if_fail (data_destroy != NULL, NULL);
+
+  cache =  g_object_new (GIMP_TYPE_BRUSH_CACHE,
+                         "data-destroy", data_destroy,
+                         NULL);
+
+  cache->debug_hit  = debug_hit;
+  cache->debug_miss = debug_miss;
+
+  return cache;
+}
+
+void
+gimp_brush_cache_clear (GimpBrushCache *cache)
+{
+  g_return_if_fail (GIMP_IS_BRUSH_CACHE (cache));
+
+  if (cache->cached_units)
+    {
+      GList *iter;
+
+      for (iter = cache->cached_units; iter; iter = g_list_next (iter))
+        {
+          GimpBrushCacheUnit *unit = iter->data;
+
+          cache->data_destroy (unit->data);
+        }
+
+      g_list_free_full (cache->cached_units, g_free);
+      cache->cached_units = NULL;
+    }
+}
+
+gconstpointer
+gimp_brush_cache_get (GimpBrushCache *cache,
+                      gint            width,
+                      gint            height,
+                      gdouble         scale,
+                      gdouble         aspect_ratio,
+                      gdouble         angle,
+                      gboolean        reflect,
+                      gdouble         hardness)
+{
+  GList *iter;
+
+  g_return_val_if_fail (GIMP_IS_BRUSH_CACHE (cache), NULL);
+
+  for (iter = cache->cached_units; iter; iter = g_list_next (iter))
+    {
+      GimpBrushCacheUnit *unit = iter->data;
+
+      if (unit->data                         &&
+          unit->width        == width        &&
+          unit->height       == height       &&
+          unit->scale        == scale        &&
+          unit->aspect_ratio == aspect_ratio &&
+          unit->angle        == angle        &&
+          unit->reflect      == reflect      &&
+          unit->hardness     == hardness)
+        {
+          if (gimp_log_flags & GIMP_LOG_BRUSH_CACHE)
+            g_printerr ("%c", cache->debug_hit);
+
+          /* Make the returned cached brush first in the list. */
+          cache->cached_units = g_list_remove_link (cache->cached_units, iter);
+          iter->next = cache->cached_units;
+          if (cache->cached_units)
+            cache->cached_units->prev = iter;
+          cache->cached_units = iter;
+
+          return (gconstpointer) unit->data;
+        }
+    }
+
+  if (gimp_log_flags & GIMP_LOG_BRUSH_CACHE)
+    g_printerr ("%c", cache->debug_miss);
+
+  return NULL;
+}
+
+void
+gimp_brush_cache_add (GimpBrushCache *cache,
+                      gpointer        data,
+                      gint            width,
+                      gint            height,
+                      gdouble         scale,
+                      gdouble         aspect_ratio,
+                      gdouble         angle,
+                      gboolean        reflect,
+                      gdouble         hardness)
+{
+  GList              *iter;
+  GimpBrushCacheUnit *unit;
+  GList              *last   = NULL;
+  gint                length = 0;
+
+  g_return_if_fail (GIMP_IS_BRUSH_CACHE (cache));
+  g_return_if_fail (data != NULL);
+
+  for (iter = cache->cached_units; iter; iter = g_list_next (iter))
+    {
+      unit = iter->data;
+
+      if (data == unit->data)
+        return;
+
+      length++;
+      last = iter;
+    }
+
+  if (length > MAX_CACHED_DATA)
+    {
+      unit = last->data;
+
+      cache->data_destroy (unit->data);
+      cache->cached_units = g_list_delete_link (cache->cached_units, last);
+      g_free (unit);
+    }
+
+  unit = g_new0 (GimpBrushCacheUnit, 1);
+
+  unit->data         = data;
+  unit->width        = width;
+  unit->height       = height;
+  unit->scale        = scale;
+  unit->aspect_ratio = aspect_ratio;
+  unit->angle        = angle;
+  unit->reflect      = reflect;
+  unit->hardness     = hardness;
+
+  cache->cached_units = g_list_prepend (cache->cached_units, unit);
+}
diff --git a/app/core/gimpbrushcache.h b/app/core/gimpbrushcache.h
new file mode 100644
index 0000000..7722117
--- /dev/null
+++ b/app/core/gimpbrushcache.h
@@ -0,0 +1,83 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpbrushcache.h
+ * Copyright (C) 2011 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_BRUSH_CACHE_H__
+#define __GIMP_BRUSH_CACHE_H__
+
+
+#include "gimpobject.h"
+
+
+#define GIMP_TYPE_BRUSH_CACHE            (gimp_brush_cache_get_type ())
+#define GIMP_BRUSH_CACHE(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_BRUSH_CACHE, GimpBrushCache))
+#define GIMP_BRUSH_CACHE_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_BRUSH_CACHE, GimpBrushCacheClass))
+#define GIMP_IS_BRUSH_CACHE(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_BRUSH_CACHE))
+#define GIMP_IS_BRUSH_CACHE_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_BRUSH_CACHE))
+#define GIMP_BRUSH_CACHE_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_BRUSH_CACHE, GimpBrushCacheClass))
+
+
+typedef struct _GimpBrushCacheClass GimpBrushCacheClass;
+
+struct _GimpBrushCache
+{
+  GimpObject      parent_instance;
+
+  GDestroyNotify  data_destroy;
+
+  GList          *cached_units;
+
+  gchar           debug_hit;
+  gchar           debug_miss;
+};
+
+struct _GimpBrushCacheClass
+{
+  GimpObjectClass  parent_class;
+};
+
+
+GType            gimp_brush_cache_get_type (void) G_GNUC_CONST;
+
+GimpBrushCache * gimp_brush_cache_new      (GDestroyNotify  data_destory,
+                                            gchar           debug_hit,
+                                            gchar           debug_miss);
+
+void             gimp_brush_cache_clear    (GimpBrushCache *cache);
+
+gconstpointer    gimp_brush_cache_get      (GimpBrushCache *cache,
+                                            gint            width,
+                                            gint            height,
+                                            gdouble         scale,
+                                            gdouble         aspect_ratio,
+                                            gdouble         angle,
+                                            gboolean        reflect,
+                                            gdouble         hardness);
+void             gimp_brush_cache_add      (GimpBrushCache *cache,
+                                            gpointer        data,
+                                            gint            width,
+                                            gint            height,
+                                            gdouble         scale,
+                                            gdouble         aspect_ratio,
+                                            gdouble         angle,
+                                            gboolean        reflect,
+                                            gdouble         hardness);
+
+
+#endif  /*  __GIMP_BRUSH_CACHE_H__  */
diff --git a/app/core/gimpbrushclipboard.c b/app/core/gimpbrushclipboard.c
new file mode 100644
index 0000000..2d4a5e1
--- /dev/null
+++ b/app/core/gimpbrushclipboard.c
@@ -0,0 +1,298 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpbrushclipboard.c
+ * Copyright (C) 2006 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gimp.h"
+#include "gimpbuffer.h"
+#include "gimpbrush-private.h"
+#include "gimpbrushclipboard.h"
+#include "gimpimage.h"
+#include "gimppickable.h"
+#include "gimptempbuf.h"
+
+#include "gimp-intl.h"
+
+
+#define BRUSH_MAX_SIZE 1024
+
+enum
+{
+  PROP_0,
+  PROP_GIMP,
+  PROP_MASK_ONLY
+};
+
+
+/*  local function prototypes  */
+
+static void       gimp_brush_clipboard_constructed  (GObject      *object);
+static void       gimp_brush_clipboard_set_property (GObject      *object,
+                                                     guint         property_id,
+                                                     const GValue *value,
+                                                     GParamSpec   *pspec);
+static void       gimp_brush_clipboard_get_property (GObject      *object,
+                                                     guint         property_id,
+                                                     GValue       *value,
+                                                     GParamSpec   *pspec);
+
+static GimpData * gimp_brush_clipboard_duplicate    (GimpData     *data);
+
+static void       gimp_brush_clipboard_changed      (Gimp         *gimp,
+                                                     GimpBrush    *brush);
+
+
+G_DEFINE_TYPE (GimpBrushClipboard, gimp_brush_clipboard, GIMP_TYPE_BRUSH)
+
+#define parent_class gimp_brush_clipboard_parent_class
+
+
+static void
+gimp_brush_clipboard_class_init (GimpBrushClipboardClass *klass)
+{
+  GObjectClass  *object_class = G_OBJECT_CLASS (klass);
+  GimpDataClass *data_class   = GIMP_DATA_CLASS (klass);
+
+  object_class->constructed  = gimp_brush_clipboard_constructed;
+  object_class->set_property = gimp_brush_clipboard_set_property;
+  object_class->get_property = gimp_brush_clipboard_get_property;
+
+  data_class->duplicate      = gimp_brush_clipboard_duplicate;
+
+  g_object_class_install_property (object_class, PROP_GIMP,
+                                   g_param_spec_object ("gimp", NULL, NULL,
+                                                        GIMP_TYPE_GIMP,
+                                                        GIMP_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT_ONLY));
+
+  g_object_class_install_property (object_class, PROP_MASK_ONLY,
+                                   g_param_spec_boolean ("mask-only", NULL, NULL,
+                                                         FALSE,
+                                                         GIMP_PARAM_READWRITE |
+                                                         G_PARAM_CONSTRUCT_ONLY));
+}
+
+static void
+gimp_brush_clipboard_init (GimpBrushClipboard *brush)
+{
+}
+
+static void
+gimp_brush_clipboard_constructed (GObject *object)
+{
+  GimpBrushClipboard *brush = GIMP_BRUSH_CLIPBOARD (object);
+
+  G_OBJECT_CLASS (parent_class)->constructed (object);
+
+  gimp_assert (GIMP_IS_GIMP (brush->gimp));
+
+  g_signal_connect_object (brush->gimp, "clipboard-changed",
+                           G_CALLBACK (gimp_brush_clipboard_changed),
+                           brush, 0);
+
+  gimp_brush_clipboard_changed (brush->gimp, GIMP_BRUSH (brush));
+}
+
+static void
+gimp_brush_clipboard_set_property (GObject      *object,
+                                   guint         property_id,
+                                   const GValue *value,
+                                   GParamSpec   *pspec)
+{
+  GimpBrushClipboard *brush = GIMP_BRUSH_CLIPBOARD (object);
+
+  switch (property_id)
+    {
+    case PROP_GIMP:
+      brush->gimp = g_value_get_object (value);
+      break;
+
+    case PROP_MASK_ONLY:
+      brush->mask_only = g_value_get_boolean (value);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_brush_clipboard_get_property (GObject    *object,
+                                   guint       property_id,
+                                   GValue     *value,
+                                   GParamSpec *pspec)
+{
+  GimpBrushClipboard *brush = GIMP_BRUSH_CLIPBOARD (object);
+
+  switch (property_id)
+    {
+    case PROP_GIMP:
+      g_value_set_object (value, brush->gimp);
+      break;
+
+    case PROP_MASK_ONLY:
+      g_value_set_boolean (value, brush->mask_only);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static GimpData *
+gimp_brush_clipboard_duplicate (GimpData *data)
+{
+  GimpData *new = g_object_new (GIMP_TYPE_BRUSH, NULL);
+
+  gimp_data_copy (new, data);
+
+  return new;
+}
+
+GimpData *
+gimp_brush_clipboard_new (Gimp     *gimp,
+                          gboolean  mask_only)
+{
+  const gchar *name;
+
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  if (mask_only)
+    name = _("Clipboard Mask");
+  else
+    name = _("Clipboard Image");
+
+  return g_object_new (GIMP_TYPE_BRUSH_CLIPBOARD,
+                       "name",      name,
+                       "gimp",      gimp,
+                       "mask-only", mask_only,
+                       NULL);
+}
+
+
+/*  private functions  */
+
+static void
+gimp_brush_clipboard_changed (Gimp      *gimp,
+                              GimpBrush *brush)
+{
+  GimpObject *paste;
+  GeglBuffer *buffer = NULL;
+  gint        width;
+  gint        height;
+
+  g_clear_pointer (&brush->priv->mask,   gimp_temp_buf_unref);
+  g_clear_pointer (&brush->priv->pixmap, gimp_temp_buf_unref);
+
+  paste = gimp_get_clipboard_object (gimp);
+
+  if (GIMP_IS_IMAGE (paste))
+    {
+      gimp_pickable_flush (GIMP_PICKABLE (paste));
+      buffer = gimp_pickable_get_buffer (GIMP_PICKABLE (paste));
+    }
+  else if (GIMP_IS_BUFFER (paste))
+    {
+      buffer = gimp_buffer_get_buffer (GIMP_BUFFER (paste));
+    }
+
+  if (buffer)
+    {
+      const Babl *format = gegl_buffer_get_format (buffer);
+
+      width  = MIN (gegl_buffer_get_width  (buffer), BRUSH_MAX_SIZE);
+      height = MIN (gegl_buffer_get_height (buffer), BRUSH_MAX_SIZE);
+
+      brush->priv->mask = gimp_temp_buf_new (width, height,
+                                             babl_format ("Y u8"));
+
+      if (GIMP_BRUSH_CLIPBOARD (brush)->mask_only)
+        {
+          guchar *p;
+          gint    i;
+
+          gegl_buffer_get (buffer,
+                           GEGL_RECTANGLE (0, 0, width, height), 1.0,
+                           babl_format ("Y u8"),
+                           gimp_temp_buf_get_data (brush->priv->mask),
+                           GEGL_AUTO_ROWSTRIDE, GEGL_ABYSS_NONE);
+
+          /*  invert the mask, it's more intuitive to think
+           *  "black on white" than the other way around
+           */
+          for (i = 0, p = gimp_temp_buf_get_data (brush->priv->mask);
+               i < width * height;
+               i++, p++)
+            {
+              *p = 255 - *p;
+            }
+        }
+      else
+        {
+          brush->priv->pixmap = gimp_temp_buf_new (width, height,
+                                                   babl_format ("R'G'B' u8"));
+
+          /*  copy the alpha channel into the brush's mask  */
+          if (babl_format_has_alpha (format))
+            {
+              gegl_buffer_get (buffer,
+                               GEGL_RECTANGLE (0, 0, width, height), 1.0,
+                               babl_format ("A u8"),
+                               gimp_temp_buf_get_data (brush->priv->mask),
+                               GEGL_AUTO_ROWSTRIDE, GEGL_ABYSS_NONE);
+            }
+          else
+            {
+              memset (gimp_temp_buf_get_data (brush->priv->mask), 255,
+                      width * height);
+            }
+
+          /*  copy the color channels into the brush's pixmap  */
+          gegl_buffer_get (buffer,
+                           GEGL_RECTANGLE (0, 0, width, height), 1.0,
+                           babl_format ("R'G'B' u8"),
+                           gimp_temp_buf_get_data (brush->priv->pixmap),
+                           GEGL_AUTO_ROWSTRIDE, GEGL_ABYSS_NONE);
+        }
+    }
+  else
+    {
+      width  = 17;
+      height = 17;
+
+      brush->priv->mask = gimp_temp_buf_new (width, height,
+                                             babl_format ("Y u8"));
+      gimp_temp_buf_data_clear (brush->priv->mask);
+    }
+
+  brush->priv->x_axis.x = width / 2;
+  brush->priv->x_axis.y = 0;
+  brush->priv->y_axis.x = 0;
+  brush->priv->y_axis.y = height / 2;
+
+  gimp_data_dirty (GIMP_DATA (brush));
+}
diff --git a/app/core/gimpbrushclipboard.h b/app/core/gimpbrushclipboard.h
new file mode 100644
index 0000000..95af7e1
--- /dev/null
+++ b/app/core/gimpbrushclipboard.h
@@ -0,0 +1,58 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpbrushclipboard.h
+ * Copyright (C) 2006 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_BRUSH_CLIPBOARD_H__
+#define __GIMP_BRUSH_CLIPBOARD_H__
+
+
+#include "gimpbrush.h"
+
+
+#define GIMP_TYPE_BRUSH_CLIPBOARD            (gimp_brush_clipboard_get_type ())
+#define GIMP_BRUSH_CLIPBOARD(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_BRUSH_CLIPBOARD, GimpBrushClipboard))
+#define GIMP_BRUSH_CLIPBOARD_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_BRUSH_CLIPBOARD, GimpBrushClipboardClass))
+#define GIMP_IS_BRUSH_CLIPBOARD(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_BRUSH_CLIPBOARD))
+#define GIMP_IS_BRUSH_CLIPBOARD_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_BRUSH_CLIPBOARD))
+#define GIMP_BRUSH_CLIPBOARD_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_BRUSH_CLIPBOARD, GimpBrushClipboardClass))
+
+
+typedef struct _GimpBrushClipboardClass GimpBrushClipboardClass;
+
+struct _GimpBrushClipboard
+{
+  GimpBrush  parent_instance;
+
+  Gimp      *gimp;
+  gboolean   mask_only;
+};
+
+struct _GimpBrushClipboardClass
+{
+  GimpBrushClass  parent_class;
+};
+
+
+GType      gimp_brush_clipboard_get_type (void) G_GNUC_CONST;
+
+GimpData * gimp_brush_clipboard_new      (Gimp     *gimp,
+                                          gboolean  mask_only);
+
+
+#endif  /*  __GIMP_BRUSH_CLIPBOARD_H__  */
diff --git a/app/core/gimpbrushgenerated-load.c b/app/core/gimpbrushgenerated-load.c
new file mode 100644
index 0000000..a526ae6
--- /dev/null
+++ b/app/core/gimpbrushgenerated-load.c
@@ -0,0 +1,284 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimp_brush_generated module Copyright 1998 Jay Cox <jaycox@earthlink.net>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <stdlib.h>
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+
+#include "core-types.h"
+
+#include "gimp-utils.h"
+#include "gimpbrushgenerated.h"
+#include "gimpbrushgenerated-load.h"
+
+#include "gimp-intl.h"
+
+
+GList *
+gimp_brush_generated_load (GimpContext   *context,
+                           GFile         *file,
+                           GInputStream  *input,
+                           GError       **error)
+{
+  GimpBrush               *brush;
+  GDataInputStream        *data_input;
+  gchar                   *string;
+  gsize                    string_len;
+  gint                     linenum;
+  gchar                   *name       = NULL;
+  GimpBrushGeneratedShape  shape      = GIMP_BRUSH_GENERATED_CIRCLE;
+  gboolean                 have_shape = FALSE;
+  gint                     spikes     = 2;
+  gdouble                  spacing;
+  gdouble                  radius;
+  gdouble                  hardness;
+  gdouble                  aspect_ratio;
+  gdouble                  angle;
+
+  g_return_val_if_fail (G_IS_FILE (file), NULL);
+  g_return_val_if_fail (G_IS_INPUT_STREAM (input), NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, NULL);
+
+  data_input = g_data_input_stream_new (input);
+
+  /* make sure the file we are reading is the right type */
+  linenum = 1;
+  string_len = 256;
+  string = gimp_data_input_stream_read_line_always (data_input, &string_len,
+                                                    NULL, error);
+  if (! string)
+    goto failed;
+
+  if (! g_str_has_prefix (string, "GIMP-VBR"))
+    {
+      g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                   _("Not a GIMP brush file."));
+      g_free (string);
+      goto failed;
+    }
+
+  g_free (string);
+
+  /* make sure we are reading a compatible version */
+  linenum++;
+  string_len = 256;
+  string = gimp_data_input_stream_read_line_always (data_input, &string_len,
+                                                    NULL, error);
+  if (! string)
+    goto failed;
+
+  if (! g_str_has_prefix (string, "1.0"))
+    {
+      if (! g_str_has_prefix (string, "1.5"))
+        {
+          g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                       _("Unknown GIMP brush version."));
+          g_free (string);
+          goto failed;
+        }
+      else
+        {
+          have_shape = TRUE;
+        }
+    }
+
+  g_free (string);
+
+  /* read name */
+  linenum++;
+  string_len = 256;
+  string = gimp_data_input_stream_read_line_always (data_input, &string_len,
+                                                    NULL, error);
+  if (! string)
+    goto failed;
+
+  g_strstrip (string);
+
+  /* the empty string is not an allowed name */
+  if (strlen (string) < 1)
+    {
+      name = g_strdup (_("Untitled"));
+    }
+  else
+    {
+      name = gimp_any_to_utf8 (string, -1,
+                               _("Invalid UTF-8 string in brush file '%s'."),
+                               gimp_file_get_utf8_name (file));
+    }
+
+  g_free (string);
+
+  if (have_shape)
+    {
+      GEnumClass *enum_class;
+      GEnumValue *shape_val;
+
+      enum_class = g_type_class_peek (GIMP_TYPE_BRUSH_GENERATED_SHAPE);
+
+      /* read shape */
+      linenum++;
+      string_len = 256;
+      string = gimp_data_input_stream_read_line_always (data_input, &string_len,
+                                                        NULL, error);
+      if (! string)
+        goto failed;
+
+      g_strstrip (string);
+      shape_val = g_enum_get_value_by_nick (enum_class, string);
+
+      if (! shape_val)
+        {
+          g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                       _("Unknown GIMP brush shape."));
+          g_free (string);
+          goto failed;
+        }
+
+      g_free (string);
+
+      shape = shape_val->value;
+    }
+
+  /* read brush spacing */
+  linenum++;
+  string_len = 256;
+  string = gimp_data_input_stream_read_line_always (data_input, &string_len,
+                                                    NULL, error);
+  if (! string)
+    goto failed;
+  if (! gimp_ascii_strtod (string, NULL, &spacing))
+    {
+      g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                   _("Invalid brush spacing."));
+      g_free (string);
+      goto failed;
+    }
+  g_free (string);
+
+
+  /* read brush radius */
+  linenum++;
+  string_len = 256;
+  string = gimp_data_input_stream_read_line_always (data_input, &string_len,
+                                                    NULL, error);
+  if (! string)
+    goto failed;
+  if (! gimp_ascii_strtod (string, NULL, &radius))
+    {
+      g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                   _("Invalid brush radius."));
+      g_free (string);
+      goto failed;
+    }
+  g_free (string);
+
+  if (have_shape)
+    {
+      /* read number of spikes */
+      linenum++;
+      string_len = 256;
+      string = gimp_data_input_stream_read_line_always (data_input, &string_len,
+                                                        NULL, error);
+      if (! string)
+        goto failed;
+      if (! gimp_ascii_strtoi (string, NULL, 10, &spikes) ||
+          spikes < 2 || spikes > 20)
+        {
+          g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                       _("Invalid brush spike count."));
+          g_free (string);
+          goto failed;
+        }
+      g_free (string);
+    }
+
+  /* read brush hardness */
+  linenum++;
+  string_len = 256;
+  string = gimp_data_input_stream_read_line_always (data_input, &string_len,
+                                                    NULL, error);
+  if (! string)
+    goto failed;
+  if (! gimp_ascii_strtod (string, NULL, &hardness))
+    {
+      g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                   _("Invalid brush hardness."));
+      g_free (string);
+      goto failed;
+    }
+  g_free (string);
+
+  /* read brush aspect_ratio */
+  linenum++;
+  string_len = 256;
+  string = gimp_data_input_stream_read_line_always (data_input, &string_len,
+                                                    NULL, error);
+  if (! string)
+    goto failed;
+  if (! gimp_ascii_strtod (string, NULL, &aspect_ratio))
+    {
+      g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                   _("Invalid brush aspect ratio."));
+      g_free (string);
+      goto failed;
+    }
+  g_free (string);
+
+  /* read brush angle */
+  linenum++;
+  string_len = 256;
+  string = gimp_data_input_stream_read_line_always (data_input, &string_len,
+                                                    NULL, error);
+  if (! string)
+    goto failed;
+  if (! gimp_ascii_strtod (string, NULL, &angle))
+    {
+      g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                   _("Invalid brush angle."));
+      g_free (string);
+      goto failed;
+    }
+  g_free (string);
+
+  g_object_unref (data_input);
+
+  brush = GIMP_BRUSH (gimp_brush_generated_new (name, shape, radius, spikes,
+                                                hardness, aspect_ratio, angle));
+  g_free (name);
+
+  gimp_brush_set_spacing (brush, spacing);
+
+  return g_list_prepend (NULL, brush);
+
+ failed:
+
+  g_object_unref (data_input);
+
+  if (name)
+    g_free (name);
+
+  g_prefix_error (error, _("In line %d of brush file: "), linenum);
+
+  return NULL;
+}
diff --git a/app/core/gimpbrushgenerated-load.h b/app/core/gimpbrushgenerated-load.h
new file mode 100644
index 0000000..afecb3b
--- /dev/null
+++ b/app/core/gimpbrushgenerated-load.h
@@ -0,0 +1,33 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * brush_generated module Copyright 1998 Jay Cox <jaycox@earthlink.net>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_BRUSH_GENERATED_LOAD_H__
+#define __GIMP_BRUSH_GENERATED_LOAD_H__
+
+
+#define GIMP_BRUSH_GENERATED_FILE_EXTENSION ".vbr"
+
+
+GList * gimp_brush_generated_load (GimpContext   *context,
+                                   GFile         *file,
+                                   GInputStream  *input,
+                                   GError       **error);
+
+
+#endif  /*  __GIMP_BRUSH_GENERATED_LOAD_H__  */
diff --git a/app/core/gimpbrushgenerated-save.c b/app/core/gimpbrushgenerated-save.c
new file mode 100644
index 0000000..2b9f8a0
--- /dev/null
+++ b/app/core/gimpbrushgenerated-save.c
@@ -0,0 +1,119 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimp_brush_generated module Copyright 1998 Jay Cox <jaycox@earthlink.net>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+
+#include "core-types.h"
+
+#include "gimpbrushgenerated.h"
+#include "gimpbrushgenerated-save.h"
+
+#include "gimp-intl.h"
+
+
+gboolean
+gimp_brush_generated_save (GimpData       *data,
+                           GOutputStream  *output,
+                           GError        **error)
+{
+  GimpBrushGenerated *brush = GIMP_BRUSH_GENERATED (data);
+  const gchar        *name  = gimp_object_get_name (data);
+  GString            *string;
+  gchar               buf[G_ASCII_DTOSTR_BUF_SIZE];
+  gboolean            have_shape = FALSE;
+
+  g_return_val_if_fail (name != NULL && *name != '\0', FALSE);
+
+  /* write magic header */
+  string = g_string_new ("GIMP-VBR\n");
+
+  /* write version */
+  if (brush->shape != GIMP_BRUSH_GENERATED_CIRCLE || brush->spikes > 2)
+    {
+      g_string_append (string, "1.5\n");
+      have_shape = TRUE;
+    }
+  else
+    {
+      g_string_append (string, "1.0\n");
+    }
+
+  /* write name */
+  g_string_append_printf (string, "%.255s\n", name);
+
+  if (have_shape)
+    {
+      GEnumClass *enum_class;
+      GEnumValue *shape_val;
+
+      enum_class = g_type_class_peek (GIMP_TYPE_BRUSH_GENERATED_SHAPE);
+
+      /* write shape */
+      shape_val = g_enum_get_value (enum_class, brush->shape);
+      g_string_append_printf (string, "%s\n", shape_val->value_nick);
+    }
+
+  /* write brush spacing */
+  g_string_append_printf (string, "%s\n",
+                          g_ascii_dtostr (buf, G_ASCII_DTOSTR_BUF_SIZE,
+                                          gimp_brush_get_spacing (GIMP_BRUSH (brush))));
+
+  /* write brush radius */
+  g_string_append_printf (string, "%s\n",
+                          g_ascii_dtostr (buf, G_ASCII_DTOSTR_BUF_SIZE,
+                                          brush->radius));
+
+  if (have_shape)
+    {
+      /* write brush spikes */
+      g_string_append_printf (string, "%d\n", brush->spikes);
+    }
+
+  /* write brush hardness */
+  g_string_append_printf (string, "%s\n",
+                          g_ascii_dtostr (buf, G_ASCII_DTOSTR_BUF_SIZE,
+                                          brush->hardness));
+
+  /* write brush aspect_ratio */
+  g_string_append_printf (string, "%s\n",
+                          g_ascii_dtostr (buf, G_ASCII_DTOSTR_BUF_SIZE,
+                                          brush->aspect_ratio));
+
+  /* write brush angle */
+  g_string_append_printf (string, "%s\n",
+                          g_ascii_dtostr (buf, G_ASCII_DTOSTR_BUF_SIZE,
+                                          brush->angle));
+
+  if (! g_output_stream_write_all (output, string->str, string->len,
+                                   NULL, NULL, error))
+    {
+      g_string_free (string, TRUE);
+
+      return FALSE;
+    }
+
+  g_string_free (string, TRUE);
+
+  return TRUE;
+}
diff --git a/app/core/gimpbrushgenerated-save.h b/app/core/gimpbrushgenerated-save.h
new file mode 100644
index 0000000..b33d82e
--- /dev/null
+++ b/app/core/gimpbrushgenerated-save.h
@@ -0,0 +1,30 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * brush_generated module Copyright 1998 Jay Cox <jaycox@earthlink.net>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_BRUSH_GENERATED_SAVE_H__
+#define __GIMP_BRUSH_GENERATED_SAVE_H__
+
+
+/*  don't call this function directly, use gimp_data_save() instead  */
+gboolean   gimp_brush_generated_save (GimpData       *data,
+                                      GOutputStream  *output,
+                                      GError        **error);
+
+
+#endif  /*  __GIMP_BRUSH_GENERATED_SAVE_H__  */
diff --git a/app/core/gimpbrushgenerated.c b/app/core/gimpbrushgenerated.c
new file mode 100644
index 0000000..dacdaa8
--- /dev/null
+++ b/app/core/gimpbrushgenerated.c
@@ -0,0 +1,875 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimp_brush_generated module Copyright 1998 Jay Cox <jaycox@earthlink.net>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpmath/gimpmath.h"
+
+#include "core-types.h"
+
+#include "gimpbrush-private.h"
+#include "gimpbrushgenerated.h"
+#include "gimpbrushgenerated-load.h"
+#include "gimpbrushgenerated-save.h"
+#include "gimptempbuf.h"
+
+#include "gimp-intl.h"
+
+
+#define OVERSAMPLING 4
+
+
+enum
+{
+  PROP_0,
+  PROP_SHAPE,
+  PROP_RADIUS,
+  PROP_SPIKES,
+  PROP_HARDNESS,
+  PROP_ASPECT_RATIO,
+  PROP_ANGLE
+};
+
+
+/*  local function prototypes  */
+
+static void          gimp_brush_generated_set_property  (GObject      *object,
+                                                         guint         property_id,
+                                                         const GValue *value,
+                                                         GParamSpec   *pspec);
+static void          gimp_brush_generated_get_property  (GObject      *object,
+                                                         guint         property_id,
+                                                         GValue       *value,
+                                                         GParamSpec   *pspec);
+
+static void          gimp_brush_generated_dirty         (GimpData     *data);
+static const gchar * gimp_brush_generated_get_extension (GimpData     *data);
+static void          gimp_brush_generated_copy          (GimpData     *data,
+                                                         GimpData     *src_data);
+
+static void          gimp_brush_generated_transform_size(GimpBrush    *gbrush,
+                                                         gdouble       scale,
+                                                         gdouble       aspect_ratio,
+                                                         gdouble       angle,
+                                                         gboolean      reflect,
+                                                         gint         *width,
+                                                         gint         *height);
+static GimpTempBuf * gimp_brush_generated_transform_mask(GimpBrush    *gbrush,
+                                                         gdouble       scale,
+                                                         gdouble       aspect_ratio,
+                                                         gdouble       angle,
+                                                         gboolean      reflect,
+                                                         gdouble       hardness);
+
+static GimpTempBuf * gimp_brush_generated_calc          (GimpBrushGenerated      *brush,
+                                                         GimpBrushGeneratedShape  shape,
+                                                         gfloat                   radius,
+                                                         gint                     spikes,
+                                                         gfloat                   hardness,
+                                                         gfloat                   aspect_ratio,
+                                                         gfloat                   angle,
+                                                         gboolean                 reflect,
+                                                         GimpVector2             *xaxis,
+                                                         GimpVector2             *yaxis);
+static void          gimp_brush_generated_get_size      (GimpBrushGenerated      *gbrush,
+                                                         GimpBrushGeneratedShape  shape,
+                                                         gfloat                   radius,
+                                                         gint                     spikes,
+                                                         gfloat                   hardness,
+                                                         gfloat                   aspect_ratio,
+                                                         gdouble                  angle_in_degrees,
+                                                         gboolean                 reflect,
+                                                         gint                    *width,
+                                                         gint                    *height,
+                                                         gdouble                 *_s,
+                                                         gdouble                 *_c,
+                                                         GimpVector2             *_x_axis,
+                                                         GimpVector2             *_y_axis);
+
+
+G_DEFINE_TYPE (GimpBrushGenerated, gimp_brush_generated, GIMP_TYPE_BRUSH)
+
+#define parent_class gimp_brush_generated_parent_class
+
+
+static void
+gimp_brush_generated_class_init (GimpBrushGeneratedClass *klass)
+{
+  GObjectClass   *object_class = G_OBJECT_CLASS (klass);
+  GimpDataClass  *data_class   = GIMP_DATA_CLASS (klass);
+  GimpBrushClass *brush_class  = GIMP_BRUSH_CLASS (klass);
+
+  object_class->set_property  = gimp_brush_generated_set_property;
+  object_class->get_property  = gimp_brush_generated_get_property;
+
+  data_class->save            = gimp_brush_generated_save;
+  data_class->dirty           = gimp_brush_generated_dirty;
+  data_class->get_extension   = gimp_brush_generated_get_extension;
+  data_class->copy            = gimp_brush_generated_copy;
+
+  brush_class->transform_size = gimp_brush_generated_transform_size;
+  brush_class->transform_mask = gimp_brush_generated_transform_mask;
+
+  g_object_class_install_property (object_class, PROP_SHAPE,
+                                   g_param_spec_enum ("shape", NULL,
+                                                      _("Brush Shape"),
+                                                      GIMP_TYPE_BRUSH_GENERATED_SHAPE,
+                                                      GIMP_BRUSH_GENERATED_CIRCLE,
+                                                      GIMP_PARAM_READWRITE |
+                                                      G_PARAM_CONSTRUCT));
+
+  g_object_class_install_property (object_class, PROP_RADIUS,
+                                   g_param_spec_double ("radius", NULL,
+                                                        _("Brush Radius"),
+                                                        0.1, 4000.0, 5.0,
+                                                        GIMP_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT));
+
+  g_object_class_install_property (object_class, PROP_SPIKES,
+                                   g_param_spec_int    ("spikes", NULL,
+                                                        _("Brush Spikes"),
+                                                        2, 20, 2,
+                                                        GIMP_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT));
+
+  g_object_class_install_property (object_class, PROP_HARDNESS,
+                                   g_param_spec_double ("hardness", NULL,
+                                                        _("Brush Hardness"),
+                                                        0.0, 1.0, 0.0,
+                                                        GIMP_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT));
+
+  g_object_class_install_property (object_class, PROP_ASPECT_RATIO,
+                                   g_param_spec_double ("aspect-ratio",
+                                                        NULL,
+                                                        _("Brush Aspect Ratio"),
+                                                        1.0, 20.0, 1.0,
+                                                        GIMP_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT));
+
+  g_object_class_install_property (object_class, PROP_ANGLE,
+                                   g_param_spec_double ("angle", NULL,
+                                                        _("Brush Angle"),
+                                                        0.0, 180.0, 0.0,
+                                                        GIMP_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT));
+}
+
+static void
+gimp_brush_generated_init (GimpBrushGenerated *brush)
+{
+  brush->shape        = GIMP_BRUSH_GENERATED_CIRCLE;
+  brush->radius       = 5.0;
+  brush->hardness     = 0.0;
+  brush->aspect_ratio = 1.0;
+  brush->angle        = 0.0;
+}
+
+static void
+gimp_brush_generated_set_property (GObject      *object,
+                                   guint         property_id,
+                                   const GValue *value,
+                                   GParamSpec   *pspec)
+{
+  GimpBrushGenerated *brush = GIMP_BRUSH_GENERATED (object);
+
+  switch (property_id)
+    {
+    case PROP_SHAPE:
+      gimp_brush_generated_set_shape (brush, g_value_get_enum (value));
+      break;
+    case PROP_RADIUS:
+      gimp_brush_generated_set_radius (brush, g_value_get_double (value));
+      break;
+    case PROP_SPIKES:
+      gimp_brush_generated_set_spikes (brush, g_value_get_int (value));
+      break;
+    case PROP_HARDNESS:
+      gimp_brush_generated_set_hardness (brush, g_value_get_double (value));
+      break;
+    case PROP_ASPECT_RATIO:
+      gimp_brush_generated_set_aspect_ratio (brush, g_value_get_double (value));
+      break;
+    case PROP_ANGLE:
+      gimp_brush_generated_set_angle (brush, g_value_get_double (value));
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_brush_generated_get_property (GObject    *object,
+                                   guint       property_id,
+                                   GValue     *value,
+                                   GParamSpec *pspec)
+{
+  GimpBrushGenerated *brush = GIMP_BRUSH_GENERATED (object);
+
+  switch (property_id)
+    {
+    case PROP_SHAPE:
+      g_value_set_enum (value, brush->shape);
+      break;
+    case PROP_RADIUS:
+      g_value_set_double (value, brush->radius);
+      break;
+    case PROP_SPIKES:
+      g_value_set_int (value, brush->spikes);
+      break;
+    case PROP_HARDNESS:
+      g_value_set_double (value, brush->hardness);
+      break;
+    case PROP_ASPECT_RATIO:
+      g_value_set_double (value, brush->aspect_ratio);
+      break;
+    case PROP_ANGLE:
+      g_value_set_double (value, brush->angle);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_brush_generated_dirty (GimpData *data)
+{
+  GimpBrushGenerated *brush  = GIMP_BRUSH_GENERATED (data);
+  GimpBrush          *gbrush = GIMP_BRUSH (brush);
+
+  g_clear_pointer (&gbrush->priv->mask, gimp_temp_buf_unref);
+
+  gbrush->priv->mask = gimp_brush_generated_calc (brush,
+                                                  brush->shape,
+                                                  brush->radius,
+                                                  brush->spikes,
+                                                  brush->hardness,
+                                                  brush->aspect_ratio,
+                                                  brush->angle,
+                                                  FALSE,
+                                                  &gbrush->priv->x_axis,
+                                                  &gbrush->priv->y_axis);
+
+  GIMP_DATA_CLASS (parent_class)->dirty (data);
+}
+
+static const gchar *
+gimp_brush_generated_get_extension (GimpData *data)
+{
+  return GIMP_BRUSH_GENERATED_FILE_EXTENSION;
+}
+
+static void
+gimp_brush_generated_copy (GimpData *data,
+                           GimpData *src_data)
+{
+  GimpBrushGenerated *brush     = GIMP_BRUSH_GENERATED (data);
+  GimpBrushGenerated *src_brush = GIMP_BRUSH_GENERATED (src_data);
+
+  gimp_data_freeze (data);
+
+  gimp_brush_set_spacing (GIMP_BRUSH (brush),
+                          gimp_brush_get_spacing (GIMP_BRUSH (src_brush)));
+
+  brush->shape        = src_brush->shape;
+  brush->radius       = src_brush->radius;
+  brush->spikes       = src_brush->spikes;
+  brush->hardness     = src_brush->hardness;
+  brush->aspect_ratio = src_brush->aspect_ratio;
+  brush->angle        = src_brush->angle;
+
+  gimp_data_thaw (data);
+}
+
+static void
+gimp_brush_generated_transform_size (GimpBrush *gbrush,
+                                     gdouble    scale,
+                                     gdouble    aspect_ratio,
+                                     gdouble    angle,
+                                     gboolean   reflect,
+                                     gint      *width,
+                                     gint      *height)
+{
+  GimpBrushGenerated *brush = GIMP_BRUSH_GENERATED (gbrush);
+  gdouble             ratio;
+
+  ratio = fabs (aspect_ratio) * 19.0 / 20.0 + 1.0;
+  ratio = MIN (ratio, 20);
+
+  /* Since generated brushes are symmetric they don't have aspect
+   * ratios < 1.0. it's the same as rotating by 90 degrees and 1 /
+   * ratio, so we fix the input for this case.
+   */
+  if (aspect_ratio < 0.0)
+    angle = angle + 0.25;
+
+  angle  = fmod (fmod (angle, 1.0) + 1.0, 1.0);
+  angle *= 360;
+
+  gimp_brush_generated_get_size (brush,
+                                 brush->shape,
+                                 brush->radius * scale,
+                                 brush->spikes,
+                                 brush->hardness,
+                                 ratio,
+                                 angle,
+                                 reflect,
+                                 width, height,
+                                 NULL, NULL, NULL, NULL);
+}
+
+static GimpTempBuf *
+gimp_brush_generated_transform_mask (GimpBrush *gbrush,
+                                     gdouble    scale,
+                                     gdouble    aspect_ratio,
+                                     gdouble    angle,
+                                     gboolean   reflect,
+                                     gdouble    hardness)
+{
+  GimpBrushGenerated *brush  = GIMP_BRUSH_GENERATED (gbrush);
+  gdouble             ratio;
+
+  ratio = fabs (aspect_ratio) * 19.0 / 20.0 + 1.0;
+  ratio = MIN (ratio, 20);
+
+  /* Since generated brushes are symmetric they don't have aspect
+   * ratios < 1.0. it's the same as rotating by 90 degrees and 1 /
+   * ratio, so we fix the input for this case.
+   */
+  if (aspect_ratio < 0.0)
+    angle = angle + 0.25;
+
+  angle  = fmod (fmod (angle, 1.0) + 1.0, 1.0);
+  angle *= 360;
+
+  if (scale    == 1.0                 &&
+      ratio    == brush->aspect_ratio &&
+      angle    == brush->angle        &&
+      reflect  == FALSE               &&
+      hardness == brush->hardness)
+    {
+      return gimp_temp_buf_copy (gimp_brush_get_mask (gbrush));
+    }
+
+  return gimp_brush_generated_calc (brush,
+                                    brush->shape,
+                                    brush->radius * scale,
+                                    brush->spikes,
+                                    hardness,
+                                    ratio,
+                                    angle,
+                                    reflect,
+                                    NULL, NULL);
+}
+
+
+/*  the actual brush rendering functions  */
+
+static gdouble
+gauss (gdouble f)
+{
+  /* this aint' a real gauss function */
+  if (f < -0.5)
+    {
+      f = -1.0 - f;
+      return (2.0 * f*f);
+    }
+
+  if (f < 0.5)
+    return (1.0 - 2.0 * f*f);
+
+  f = 1.0 - f;
+  return (2.0 * f*f);
+}
+
+/* set up lookup table */
+static gfloat *
+gimp_brush_generated_calc_lut (gdouble radius,
+                               gdouble hardness)
+{
+  gfloat  *lookup;
+  gint     length;
+  gint     x;
+  gdouble  d;
+  gdouble  sum;
+  gdouble  exponent;
+  gdouble  buffer[OVERSAMPLING];
+
+  length = OVERSAMPLING * ceil (1 + sqrt (2 * SQR (ceil (radius + 1.0))));
+
+  lookup = gegl_scratch_new (gfloat, length);
+  sum = 0.0;
+
+  if ((1.0 - hardness) < 0.0000004)
+    exponent = 1000000.0;
+  else
+    exponent = 0.4 / (1.0 - hardness);
+
+  for (x = 0; x < OVERSAMPLING; x++)
+    {
+      d = fabs ((x + 0.5) / OVERSAMPLING - 0.5);
+
+      if (d > radius)
+        buffer[x] = 0.0;
+      else
+        buffer[x] = gauss (pow (d / radius, exponent));
+
+      sum += buffer[x];
+    }
+
+  for (x = 0; d < radius || sum > 0.00001; d += 1.0 / OVERSAMPLING)
+    {
+      sum -= buffer[x % OVERSAMPLING];
+
+      if (d > radius)
+        buffer[x % OVERSAMPLING] = 0.0;
+      else
+        buffer[x % OVERSAMPLING] = gauss (pow (d / radius, exponent));
+
+      sum += buffer[x % OVERSAMPLING];
+      lookup[x++] = sum / OVERSAMPLING;
+    }
+
+  while (x < length)
+    {
+      lookup[x++] = 0.0f;
+    }
+
+  return lookup;
+}
+
+static GimpTempBuf *
+gimp_brush_generated_calc (GimpBrushGenerated      *brush,
+                           GimpBrushGeneratedShape  shape,
+                           gfloat                   radius,
+                           gint                     spikes,
+                           gfloat                   hardness,
+                           gfloat                   aspect_ratio,
+                           gfloat                   angle,
+                           gboolean                 reflect,
+                           GimpVector2             *xaxis,
+                           GimpVector2             *yaxis)
+{
+  gfloat      *centerp;
+  gfloat      *lookup;
+  gfloat       a;
+  gint         x, y;
+  gdouble      c, s, cs, ss;
+  GimpVector2  x_axis;
+  GimpVector2  y_axis;
+  GimpTempBuf *mask;
+  gint         width;
+  gint         height;
+  gint         half_width;
+  gint         half_height;
+
+  gimp_brush_generated_get_size (brush,
+                                 shape,
+                                 radius,
+                                 spikes,
+                                 hardness,
+                                 aspect_ratio,
+                                 angle,
+                                 reflect,
+                                 &width, &height,
+                                 &s, &c, &x_axis, &y_axis);
+
+  mask = gimp_temp_buf_new (width, height,
+                            babl_format ("Y float"));
+
+  half_width  = width  / 2;
+  half_height = height / 2;
+
+  centerp = (gfloat *) gimp_temp_buf_get_data (mask) +
+            half_height * width + half_width;
+
+  lookup = gimp_brush_generated_calc_lut (radius, hardness);
+
+  cs = cos (- 2 * G_PI / spikes);
+  ss = sin (- 2 * G_PI / spikes);
+
+  /* for an even number of spikes compute one half and mirror it */
+  for (y = ((spikes % 2) ? -half_height : 0); y <= half_height; y++)
+    {
+      for (x = -half_width; x <= half_width; x++)
+        {
+          gdouble d  = 0;
+          gdouble tx = c * x - s * y;
+          gdouble ty = fabs (s * x + c * y);
+
+          if (spikes > 2)
+            {
+              gdouble angle = atan2 (ty, tx);
+
+              while (angle > G_PI / spikes)
+                {
+                  gdouble sx = tx;
+                  gdouble sy = ty;
+
+                  tx = cs * sx - ss * sy;
+                  ty = ss * sx + cs * sy;
+
+                  angle -= 2 * G_PI / spikes;
+                }
+            }
+
+          ty *= aspect_ratio;
+
+          switch (shape)
+            {
+            case GIMP_BRUSH_GENERATED_CIRCLE:
+              d = sqrt (SQR (tx) + SQR (ty));
+              break;
+            case GIMP_BRUSH_GENERATED_SQUARE:
+              d = MAX (fabs (tx), fabs (ty));
+              break;
+            case GIMP_BRUSH_GENERATED_DIAMOND:
+              d = fabs (tx) + fabs (ty);
+              break;
+            }
+
+          if (d < radius + 1)
+            a = lookup[(gint) RINT (d * OVERSAMPLING)];
+          else
+            a = 0.0f;
+
+          centerp[y * width + x] = a;
+
+          if (spikes % 2 == 0)
+            centerp[-1 * y * width - x] = a;
+        }
+    }
+
+  gegl_scratch_free (lookup);
+
+  if (xaxis)
+    *xaxis = x_axis;
+
+  if (yaxis)
+    *yaxis = y_axis;
+
+  return mask;
+}
+
+/* This function is shared between gimp_brush_generated_transform_size and
+ * gimp_brush_generated_calc, therefore we provide a bunch of optional
+ * pointers for returnvalues.
+ */
+static void
+gimp_brush_generated_get_size (GimpBrushGenerated      *gbrush,
+                               GimpBrushGeneratedShape  shape,
+                               gfloat                   radius,
+                               gint                     spikes,
+                               gfloat                   hardness,
+                               gfloat                   aspect_ratio,
+                               gdouble                  angle_in_degrees,
+                               gboolean                 reflect,
+                               gint                    *width,
+                               gint                    *height,
+                               gdouble                 *_s,
+                               gdouble                 *_c,
+                               GimpVector2             *_x_axis,
+                               GimpVector2             *_y_axis)
+{
+  gdouble      half_width  = 0.0;
+  gdouble      half_height = 0.0;
+  gint         w, h;
+  gdouble      c, s;
+  gdouble      short_radius;
+  GimpVector2  x_axis;
+  GimpVector2  y_axis;
+
+  /* Since floatongpoint is not really accurate,
+   * we need to round to limit the errors.
+   * Errors in some border cases resulted in
+   * different height and width reported for
+   * the same input value on calling procedure side.
+   * This became problem at the rise of dynamics that
+   * allows for any angle to turn up.
+   **/
+
+  angle_in_degrees = RINT (angle_in_degrees * 1000.0) / 1000.0;
+
+  s = sin (gimp_deg_to_rad (angle_in_degrees));
+  c = cos (gimp_deg_to_rad (angle_in_degrees));
+
+  if (reflect)
+    c = -c;
+
+  short_radius = radius / aspect_ratio;
+
+  x_axis.x =        c * radius;
+  x_axis.y = -1.0 * s * radius;
+  y_axis.x =        s * short_radius;
+  y_axis.y =        c * short_radius;
+
+  switch (shape)
+    {
+    case GIMP_BRUSH_GENERATED_CIRCLE:
+      half_width  = sqrt (x_axis.x * x_axis.x + y_axis.x * y_axis.x);
+      half_height = sqrt (x_axis.y * x_axis.y + y_axis.y * y_axis.y);
+      break;
+
+    case GIMP_BRUSH_GENERATED_SQUARE:
+      half_width  = fabs (x_axis.x) + fabs (y_axis.x);
+      half_height = fabs (x_axis.y) + fabs (y_axis.y);
+      break;
+
+    case GIMP_BRUSH_GENERATED_DIAMOND:
+      half_width  = MAX (fabs (x_axis.x), fabs (y_axis.x));
+      half_height = MAX (fabs (x_axis.y), fabs (y_axis.y));
+      break;
+    }
+
+  if (spikes > 2)
+    {
+      /* could be optimized by respecting the angle */
+      half_width = half_height = sqrt (radius * radius +
+                                       short_radius * short_radius);
+      y_axis.x = s * radius;
+      y_axis.y = c * radius;
+    }
+
+  w = MAX (1, ceil (half_width  * 2));
+  h = MAX (1, ceil (half_height * 2));
+
+  if (! (w & 0x1)) w++;
+  if (! (h & 0x1)) h++;
+
+  *width  = w;
+  *height = h;
+
+  /*  These will typically be set then this function is called by
+   *  gimp_brush_generated_calc, which needs the values in its algorithms.
+   */
+  if (_s != NULL)
+    *_s = s;
+
+  if (_c != NULL)
+    *_c = c;
+
+  if (_x_axis != NULL)
+    *_x_axis = x_axis;
+
+  if (_y_axis != NULL)
+    *_y_axis = y_axis;
+}
+
+
+/*  public functions  */
+
+GimpData *
+gimp_brush_generated_new (const gchar             *name,
+                          GimpBrushGeneratedShape  shape,
+                          gfloat                   radius,
+                          gint                     spikes,
+                          gfloat                   hardness,
+                          gfloat                   aspect_ratio,
+                          gfloat                   angle)
+{
+  GimpBrushGenerated *brush;
+
+  g_return_val_if_fail (name != NULL, NULL);
+  g_return_val_if_fail (*name != '\0', NULL);
+
+  brush = g_object_new (GIMP_TYPE_BRUSH_GENERATED,
+                        "name",         name,
+                        "mime-type",    "application/x-gimp-brush-generated",
+                        "spacing",      20.0,
+                        "shape",        shape,
+                        "radius",       radius,
+                        "spikes",       spikes,
+                        "hardness",     hardness,
+                        "aspect-ratio", aspect_ratio,
+                        "angle",        angle,
+                        NULL);
+
+  return GIMP_DATA (brush);
+}
+
+GimpBrushGeneratedShape
+gimp_brush_generated_set_shape (GimpBrushGenerated      *brush,
+                                GimpBrushGeneratedShape  shape)
+{
+  g_return_val_if_fail (GIMP_IS_BRUSH_GENERATED (brush),
+                        GIMP_BRUSH_GENERATED_CIRCLE);
+
+  if (brush->shape != shape)
+    {
+      brush->shape = shape;
+
+      g_object_notify (G_OBJECT (brush), "shape");
+      gimp_data_dirty (GIMP_DATA (brush));
+    }
+
+  return brush->shape;
+}
+
+gfloat
+gimp_brush_generated_set_radius (GimpBrushGenerated *brush,
+                                 gfloat              radius)
+{
+  g_return_val_if_fail (GIMP_IS_BRUSH_GENERATED (brush), -1.0);
+
+  radius = CLAMP (radius, 0.0, 32767.0);
+
+  if (brush->radius != radius)
+    {
+      brush->radius = radius;
+
+      g_object_notify (G_OBJECT (brush), "radius");
+      gimp_data_dirty (GIMP_DATA (brush));
+    }
+
+  return brush->radius;
+}
+
+gint
+gimp_brush_generated_set_spikes (GimpBrushGenerated *brush,
+                                 gint                spikes)
+{
+  g_return_val_if_fail (GIMP_IS_BRUSH_GENERATED (brush), -1);
+
+  spikes = CLAMP (spikes, 2, 20);
+
+  if (brush->spikes != spikes)
+    {
+      brush->spikes = spikes;
+
+      g_object_notify (G_OBJECT (brush), "spikes");
+      gimp_data_dirty (GIMP_DATA (brush));
+    }
+
+  return brush->spikes;
+}
+
+gfloat
+gimp_brush_generated_set_hardness (GimpBrushGenerated *brush,
+                                   gfloat              hardness)
+{
+  g_return_val_if_fail (GIMP_IS_BRUSH_GENERATED (brush), -1.0);
+
+  hardness = CLAMP (hardness, 0.0, 1.0);
+
+  if (brush->hardness != hardness)
+    {
+      brush->hardness = hardness;
+
+      g_object_notify (G_OBJECT (brush), "hardness");
+      gimp_data_dirty (GIMP_DATA (brush));
+    }
+
+  return brush->hardness;
+}
+
+gfloat
+gimp_brush_generated_set_aspect_ratio (GimpBrushGenerated *brush,
+                                       gfloat              ratio)
+{
+  g_return_val_if_fail (GIMP_IS_BRUSH_GENERATED (brush), -1.0);
+
+  ratio = CLAMP (ratio, 1.0, 1000.0);
+
+  if (brush->aspect_ratio != ratio)
+    {
+      brush->aspect_ratio = ratio;
+
+      g_object_notify (G_OBJECT (brush), "aspect-ratio");
+      gimp_data_dirty (GIMP_DATA (brush));
+    }
+
+  return brush->aspect_ratio;
+}
+
+gfloat
+gimp_brush_generated_set_angle (GimpBrushGenerated *brush,
+                                gfloat              angle)
+{
+  g_return_val_if_fail (GIMP_IS_BRUSH_GENERATED (brush), -1.0);
+
+  if (angle < 0.0)
+    angle = -1.0 * fmod (angle, 180.0);
+  else if (angle > 180.0)
+    angle = fmod (angle, 180.0);
+
+  if (brush->angle != angle)
+    {
+      brush->angle = angle;
+
+      g_object_notify (G_OBJECT (brush), "angle");
+      gimp_data_dirty (GIMP_DATA (brush));
+    }
+
+  return brush->angle;
+}
+
+GimpBrushGeneratedShape
+gimp_brush_generated_get_shape (GimpBrushGenerated *brush)
+{
+  g_return_val_if_fail (GIMP_IS_BRUSH_GENERATED (brush),
+                        GIMP_BRUSH_GENERATED_CIRCLE);
+
+  return brush->shape;
+}
+
+gfloat
+gimp_brush_generated_get_radius (GimpBrushGenerated *brush)
+{
+  g_return_val_if_fail (GIMP_IS_BRUSH_GENERATED (brush), -1.0);
+
+  return brush->radius;
+}
+
+gint
+gimp_brush_generated_get_spikes (GimpBrushGenerated *brush)
+{
+  g_return_val_if_fail (GIMP_IS_BRUSH_GENERATED (brush), -1);
+
+  return brush->spikes;
+}
+
+gfloat
+gimp_brush_generated_get_hardness (GimpBrushGenerated *brush)
+{
+  g_return_val_if_fail (GIMP_IS_BRUSH_GENERATED (brush), -1.0);
+
+  return brush->hardness;
+}
+
+gfloat
+gimp_brush_generated_get_aspect_ratio (GimpBrushGenerated *brush)
+{
+  g_return_val_if_fail (GIMP_IS_BRUSH_GENERATED (brush), -1.0);
+
+  return brush->aspect_ratio;
+}
+
+gfloat
+gimp_brush_generated_get_angle (GimpBrushGenerated *brush)
+{
+  g_return_val_if_fail (GIMP_IS_BRUSH_GENERATED (brush), -1.0);
+
+  return brush->angle;
+}
diff --git a/app/core/gimpbrushgenerated.h b/app/core/gimpbrushgenerated.h
new file mode 100644
index 0000000..2df3578
--- /dev/null
+++ b/app/core/gimpbrushgenerated.h
@@ -0,0 +1,88 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * brush_generated module Copyright 1998 Jay Cox <jaycox@earthlink.net>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_BRUSH_GENERATED_H__
+#define __GIMP_BRUSH_GENERATED_H__
+
+
+#include "gimpbrush.h"
+
+
+#define GIMP_TYPE_BRUSH_GENERATED            (gimp_brush_generated_get_type ())
+#define GIMP_BRUSH_GENERATED(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_BRUSH_GENERATED, GimpBrushGenerated))
+#define GIMP_BRUSH_GENERATED_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_BRUSH_GENERATED, GimpBrushGeneratedClass))
+#define GIMP_IS_BRUSH_GENERATED(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_BRUSH_GENERATED))
+#define GIMP_IS_BRUSH_GENERATED_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_BRUSH_GENERATED))
+#define GIMP_BRUSH_GENERATED_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_BRUSH_GENERATED, GimpBrushGeneratedClass))
+
+
+typedef struct _GimpBrushGeneratedClass GimpBrushGeneratedClass;
+
+struct _GimpBrushGenerated
+{
+  GimpBrush               parent_instance;
+
+  GimpBrushGeneratedShape shape;
+  gfloat                  radius;
+  gint                    spikes;       /* 2 - 20     */
+  gfloat                  hardness;     /* 0.0 - 1.0  */
+  gfloat                  aspect_ratio; /* y/x        */
+  gfloat                  angle;        /* in degrees */
+};
+
+struct _GimpBrushGeneratedClass
+{
+  GimpBrushClass  parent_class;
+};
+
+
+GType       gimp_brush_generated_get_type     (void) G_GNUC_CONST;
+
+GimpData  * gimp_brush_generated_new          (const gchar             *name,
+                                               GimpBrushGeneratedShape  shape,
+                                               gfloat                   radius,
+                                               gint                     spikes,
+                                               gfloat                   hardness,
+                                               gfloat                   aspect_ratio,
+                                               gfloat                   angle);
+
+GimpBrushGeneratedShape
+        gimp_brush_generated_set_shape        (GimpBrushGenerated      *brush,
+                                               GimpBrushGeneratedShape  shape);
+gfloat  gimp_brush_generated_set_radius       (GimpBrushGenerated      *brush,
+                                               gfloat                   radius);
+gint    gimp_brush_generated_set_spikes       (GimpBrushGenerated      *brush,
+                                               gint                     spikes);
+gfloat  gimp_brush_generated_set_hardness     (GimpBrushGenerated      *brush,
+                                               gfloat                   hardness);
+gfloat  gimp_brush_generated_set_aspect_ratio (GimpBrushGenerated      *brush,
+                                               gfloat                   ratio);
+gfloat  gimp_brush_generated_set_angle        (GimpBrushGenerated      *brush,
+                                               gfloat                   angle);
+
+GimpBrushGeneratedShape
+        gimp_brush_generated_get_shape        (GimpBrushGenerated      *brush);
+gfloat  gimp_brush_generated_get_radius       (GimpBrushGenerated      *brush);
+gint    gimp_brush_generated_get_spikes       (GimpBrushGenerated      *brush);
+gfloat  gimp_brush_generated_get_hardness     (GimpBrushGenerated      *brush);
+gfloat  gimp_brush_generated_get_aspect_ratio (GimpBrushGenerated      *brush);
+gfloat  gimp_brush_generated_get_angle        (GimpBrushGenerated      *brush);
+
+
+#endif  /*  __GIMP_BRUSH_GENERATED_H__  */
diff --git a/app/core/gimpbrushpipe-load.c b/app/core/gimpbrushpipe-load.c
new file mode 100644
index 0000000..18ad898
--- /dev/null
+++ b/app/core/gimpbrushpipe-load.c
@@ -0,0 +1,163 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ * Copyright (C) 1999 Adrian Likins and Tor Lillqvist
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <stdlib.h>
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "libgimpbase/gimpbase.h"
+
+#include "core-types.h"
+
+#include "gimpbrush-load.h"
+#include "gimpbrush-private.h"
+#include "gimpbrushpipe.h"
+#include "gimpbrushpipe-load.h"
+
+#include "gimp-intl.h"
+
+
+GList *
+gimp_brush_pipe_load (GimpContext   *context,
+                      GFile         *file,
+                      GInputStream  *input,
+                      GError       **error)
+{
+  GimpBrushPipe *pipe      = NULL;
+  gint           n_brushes = 0;
+  GString       *buffer;
+  gchar         *paramstring;
+  gchar          c;
+  gsize          bytes_read;
+
+  g_return_val_if_fail (G_IS_FILE (file), NULL);
+  g_return_val_if_fail (G_IS_INPUT_STREAM (input), NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, NULL);
+
+  /* The file format starts with a painfully simple text header */
+
+  /*  get the name  */
+  buffer = g_string_new (NULL);
+  while (g_input_stream_read_all (input, &c, 1, &bytes_read, NULL, NULL) &&
+         bytes_read == 1 &&
+         c != '\n'       &&
+         buffer->len < 1024)
+    {
+      g_string_append_c (buffer, c);
+    }
+
+  if (buffer->len > 0 && buffer->len < 1024)
+    {
+      gchar *utf8 =
+        gimp_any_to_utf8 (buffer->str, buffer->len,
+                          _("Invalid UTF-8 string in brush file '%s'."),
+                          gimp_file_get_utf8_name (file));
+
+      pipe = g_object_new (GIMP_TYPE_BRUSH_PIPE,
+                           "name",      utf8,
+                           "mime-type", "image/x-gimp-gih",
+                           NULL);
+
+      g_free (utf8);
+    }
+
+  g_string_free (buffer, TRUE);
+
+  if (! pipe)
+    {
+      g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                   _("Fatal parse error in brush file '%s': "
+                     "File is corrupt."),
+                   gimp_file_get_utf8_name (file));
+      return NULL;
+    }
+
+  /*  get the number of brushes  */
+  buffer = g_string_new (NULL);
+  while (g_input_stream_read_all (input, &c, 1, &bytes_read, NULL, NULL) &&
+         bytes_read == 1 &&
+         c != '\n'       &&
+         buffer->len < 1024)
+    {
+      g_string_append_c (buffer, c);
+    }
+
+  if (buffer->len > 0 && buffer->len < 1024)
+    {
+      n_brushes = strtol (buffer->str, &paramstring, 10);
+    }
+
+  if (n_brushes < 1)
+    {
+      g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                   _("Fatal parse error in brush file '%s': "
+                     "File is corrupt."),
+                   gimp_file_get_utf8_name (file));
+      g_object_unref (pipe);
+      g_string_free (buffer, TRUE);
+      return NULL;
+    }
+
+  while (*paramstring && g_ascii_isspace (*paramstring))
+    paramstring++;
+
+  pipe->brushes = g_new0 (GimpBrush *, n_brushes);
+
+  while (pipe->n_brushes < n_brushes)
+    {
+      pipe->brushes[pipe->n_brushes] = gimp_brush_load_brush (context,
+                                                              file, input,
+                                                              error);
+
+      if (! pipe->brushes[pipe->n_brushes])
+        {
+          g_object_unref (pipe);
+          g_string_free (buffer, TRUE);
+          return NULL;
+        }
+
+      pipe->n_brushes++;
+    }
+
+  if (! gimp_brush_pipe_set_params (pipe, paramstring))
+    {
+      g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                   _("Fatal parse error in brush file '%s': "
+                     "Inconsistent parameters."),
+                   gimp_file_get_utf8_name (file));
+      g_object_unref (pipe);
+      g_string_free (buffer, TRUE);
+      return NULL;
+    }
+
+  g_string_free (buffer, TRUE);
+
+  /* Current brush is the first one. */
+  pipe->current = pipe->brushes[0];
+
+  /*  just to satisfy the code that relies on this crap  */
+  GIMP_BRUSH (pipe)->priv->spacing  = pipe->current->priv->spacing;
+  GIMP_BRUSH (pipe)->priv->x_axis   = pipe->current->priv->x_axis;
+  GIMP_BRUSH (pipe)->priv->y_axis   = pipe->current->priv->y_axis;
+  GIMP_BRUSH (pipe)->priv->mask     = pipe->current->priv->mask;
+  GIMP_BRUSH (pipe)->priv->pixmap   = pipe->current->priv->pixmap;
+
+  return g_list_prepend (NULL, pipe);
+}
diff --git a/app/core/gimpbrushpipe-load.h b/app/core/gimpbrushpipe-load.h
new file mode 100644
index 0000000..7426fcb
--- /dev/null
+++ b/app/core/gimpbrushpipe-load.h
@@ -0,0 +1,32 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ * Copyright (C) 1999 Adrian Likins and Tor Lillqvist
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_BRUSH_PIPE_LOAD_H__
+#define __GIMP_BRUSH_PIPE_LOAD_H__
+
+
+#define GIMP_BRUSH_PIPE_FILE_EXTENSION ".gih"
+
+
+GList * gimp_brush_pipe_load (GimpContext   *context,
+                              GFile         *file,
+                              GInputStream  *input,
+                              GError       **error);
+
+
+#endif  /* __GIMP_BRUSH_PIPE_LOAD_H__ */
diff --git a/app/core/gimpbrushpipe-save.c b/app/core/gimpbrushpipe-save.c
new file mode 100644
index 0000000..1b8e7fb
--- /dev/null
+++ b/app/core/gimpbrushpipe-save.c
@@ -0,0 +1,59 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "core-types.h"
+
+#include "gimpbrushpipe.h"
+#include "gimpbrushpipe-save.h"
+
+
+gboolean
+gimp_brush_pipe_save (GimpData       *data,
+                      GOutputStream  *output,
+                      GError        **error)
+{
+  GimpBrushPipe *pipe = GIMP_BRUSH_PIPE (data);
+  const gchar   *name;
+  gint           i;
+
+  name = gimp_object_get_name (pipe);
+
+  if (! g_output_stream_printf (output, NULL, NULL, error,
+                                "%s\n%d %s\n",
+                                name, pipe->n_brushes, pipe->params))
+    {
+      return FALSE;
+    }
+
+  for (i = 0; i < pipe->n_brushes; i++)
+    {
+      GimpBrush *brush = pipe->brushes[i];
+
+      if (brush &&
+          ! GIMP_DATA_GET_CLASS (brush)->save (GIMP_DATA (brush),
+                                               output, error))
+        {
+          return FALSE;
+        }
+    }
+
+  return TRUE;
+}
diff --git a/app/core/gimpbrushpipe-save.h b/app/core/gimpbrushpipe-save.h
new file mode 100644
index 0000000..df76855
--- /dev/null
+++ b/app/core/gimpbrushpipe-save.h
@@ -0,0 +1,28 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_BRUSH_PIPE_SAVE_H__
+#define __GIMP_BRUSH_PIPE_SAVE_H__
+
+
+/*  don't call this function directly, use gimp_data_save() instead  */
+gboolean   gimp_brush_pipe_save (GimpData       *data,
+                                 GOutputStream  *output,
+                                 GError        **error);
+
+
+#endif  /*  __GIMP_BRUSH_PIPE_SAVE_H__  */
diff --git a/app/core/gimpbrushpipe.c b/app/core/gimpbrushpipe.c
new file mode 100644
index 0000000..cca68ad
--- /dev/null
+++ b/app/core/gimpbrushpipe.c
@@ -0,0 +1,420 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ * Copyright (C) 1999 Adrian Likins and Tor Lillqvist
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpparasiteio.h"
+#include "libgimpmath/gimpmath.h"
+
+#include "core-types.h"
+
+#include "gimpbrush-private.h"
+#include "gimpbrushpipe.h"
+#include "gimpbrushpipe-load.h"
+#include "gimpbrushpipe-save.h"
+#include "gimptempbuf.h"
+
+
+static void          gimp_brush_pipe_finalize         (GObject          *object);
+
+static gint64        gimp_brush_pipe_get_memsize      (GimpObject       *object,
+                                                       gint64           *gui_size);
+
+static gboolean      gimp_brush_pipe_get_popup_size   (GimpViewable     *viewable,
+                                                       gint              width,
+                                                       gint              height,
+                                                       gboolean          dot_for_dot,
+                                                       gint             *popup_width,
+                                                       gint             *popup_height);
+
+static const gchar * gimp_brush_pipe_get_extension    (GimpData         *data);
+static void          gimp_brush_pipe_copy             (GimpData         *data,
+                                                       GimpData         *src_data);
+
+static void          gimp_brush_pipe_begin_use        (GimpBrush        *brush);
+static void          gimp_brush_pipe_end_use          (GimpBrush        *brush);
+static GimpBrush   * gimp_brush_pipe_select_brush     (GimpBrush        *brush,
+                                                       const GimpCoords *last_coords,
+                                                       const GimpCoords *current_coords);
+static gboolean      gimp_brush_pipe_want_null_motion (GimpBrush        *brush,
+                                                       const GimpCoords *last_coords,
+                                                       const GimpCoords *current_coords);
+
+
+G_DEFINE_TYPE (GimpBrushPipe, gimp_brush_pipe, GIMP_TYPE_BRUSH);
+
+#define parent_class gimp_brush_pipe_parent_class
+
+
+static void
+gimp_brush_pipe_class_init (GimpBrushPipeClass *klass)
+{
+  GObjectClass      *object_class      = G_OBJECT_CLASS (klass);
+  GimpObjectClass   *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+  GimpViewableClass *viewable_class    = GIMP_VIEWABLE_CLASS (klass);
+  GimpDataClass     *data_class        = GIMP_DATA_CLASS (klass);
+  GimpBrushClass    *brush_class       = GIMP_BRUSH_CLASS (klass);
+
+  object_class->finalize         = gimp_brush_pipe_finalize;
+
+  gimp_object_class->get_memsize = gimp_brush_pipe_get_memsize;
+
+  viewable_class->get_popup_size = gimp_brush_pipe_get_popup_size;
+
+  data_class->save               = gimp_brush_pipe_save;
+  data_class->get_extension      = gimp_brush_pipe_get_extension;
+  data_class->copy               = gimp_brush_pipe_copy;
+
+  brush_class->begin_use         = gimp_brush_pipe_begin_use;
+  brush_class->end_use           = gimp_brush_pipe_end_use;
+  brush_class->select_brush      = gimp_brush_pipe_select_brush;
+  brush_class->want_null_motion  = gimp_brush_pipe_want_null_motion;
+}
+
+static void
+gimp_brush_pipe_init (GimpBrushPipe *pipe)
+{
+  pipe->current   = NULL;
+  pipe->dimension = 0;
+  pipe->rank      = NULL;
+  pipe->stride    = NULL;
+  pipe->n_brushes = 0;
+  pipe->brushes   = NULL;
+  pipe->select    = NULL;
+  pipe->index     = NULL;
+}
+
+static void
+gimp_brush_pipe_finalize (GObject *object)
+{
+  GimpBrushPipe *pipe = GIMP_BRUSH_PIPE (object);
+
+  g_clear_pointer (&pipe->rank,   g_free);
+  g_clear_pointer (&pipe->stride, g_free);
+  g_clear_pointer (&pipe->select, g_free);
+  g_clear_pointer (&pipe->index,  g_free);
+  g_clear_pointer (&pipe->params, g_free);
+
+  if (pipe->brushes)
+    {
+      gint i;
+
+      for (i = 0; i < pipe->n_brushes; i++)
+        if (pipe->brushes[i])
+          g_object_unref (pipe->brushes[i]);
+
+      g_clear_pointer (&pipe->brushes, g_free);
+    }
+
+  GIMP_BRUSH (pipe)->priv->mask   = NULL;
+  GIMP_BRUSH (pipe)->priv->pixmap = NULL;
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static gint64
+gimp_brush_pipe_get_memsize (GimpObject *object,
+                             gint64     *gui_size)
+{
+  GimpBrushPipe *pipe    = GIMP_BRUSH_PIPE (object);
+  gint64         memsize = 0;
+  gint           i;
+
+  memsize += pipe->dimension * (sizeof (gint) /* rank   */ +
+                                sizeof (gint) /* stride */ +
+                                sizeof (PipeSelectModes));
+
+  for (i = 0; i < pipe->n_brushes; i++)
+    memsize += gimp_object_get_memsize (GIMP_OBJECT (pipe->brushes[i]),
+                                        gui_size);
+
+  return memsize + GIMP_OBJECT_CLASS (parent_class)->get_memsize (object,
+                                                                  gui_size);
+}
+
+static gboolean
+gimp_brush_pipe_get_popup_size (GimpViewable *viewable,
+                                gint          width,
+                                gint          height,
+                                gboolean      dot_for_dot,
+                                gint         *popup_width,
+                                gint         *popup_height)
+{
+  return gimp_viewable_get_size (viewable, popup_width, popup_height);
+}
+
+static const gchar *
+gimp_brush_pipe_get_extension (GimpData *data)
+{
+  return GIMP_BRUSH_PIPE_FILE_EXTENSION;
+}
+
+static void
+gimp_brush_pipe_copy (GimpData *data,
+                      GimpData *src_data)
+{
+  GimpBrushPipe *pipe     = GIMP_BRUSH_PIPE (data);
+  GimpBrushPipe *src_pipe = GIMP_BRUSH_PIPE (src_data);
+  gint           i;
+
+  pipe->dimension = src_pipe->dimension;
+
+  g_clear_pointer (&pipe->rank, g_free);
+  pipe->rank = g_memdup (src_pipe->rank,
+                         pipe->dimension * sizeof (gint));
+
+  g_clear_pointer (&pipe->stride, g_free);
+  pipe->stride = g_memdup (src_pipe->stride,
+                           pipe->dimension * sizeof (gint));
+
+  g_clear_pointer (&pipe->select, g_free);
+  pipe->select = g_memdup (src_pipe->select,
+                           pipe->dimension * sizeof (PipeSelectModes));
+
+  g_clear_pointer (&pipe->index, g_free);
+  pipe->index = g_memdup (src_pipe->index,
+                          pipe->dimension * sizeof (gint));
+
+  for (i = 0; i < pipe->n_brushes; i++)
+    if (pipe->brushes[i])
+      g_object_unref (pipe->brushes[i]);
+  g_clear_pointer (&pipe->brushes, g_free);
+
+  pipe->n_brushes = src_pipe->n_brushes;
+
+  pipe->brushes = g_new0 (GimpBrush *, pipe->n_brushes);
+  for (i = 0; i < pipe->n_brushes; i++)
+    if (src_pipe->brushes[i])
+      {
+        pipe->brushes[i] =
+          GIMP_BRUSH (gimp_data_duplicate (GIMP_DATA (src_pipe->brushes[i])));
+        gimp_object_set_name (GIMP_OBJECT (pipe->brushes[i]),
+                              gimp_object_get_name (src_pipe->brushes[i]));
+      }
+
+  g_clear_pointer (&pipe->params, g_free);
+  pipe->params = g_strdup (src_pipe->params);
+
+  pipe->current = pipe->brushes[0];
+
+  GIMP_BRUSH (pipe)->priv->spacing  = pipe->current->priv->spacing;
+  GIMP_BRUSH (pipe)->priv->x_axis   = pipe->current->priv->x_axis;
+  GIMP_BRUSH (pipe)->priv->y_axis   = pipe->current->priv->y_axis;
+  GIMP_BRUSH (pipe)->priv->mask     = pipe->current->priv->mask;
+  GIMP_BRUSH (pipe)->priv->pixmap   = pipe->current->priv->pixmap;
+
+  gimp_data_dirty (data);
+}
+
+static void
+gimp_brush_pipe_begin_use (GimpBrush *brush)
+{
+  GimpBrushPipe *pipe = GIMP_BRUSH_PIPE (brush);
+  gint           i;
+
+  GIMP_BRUSH_CLASS (parent_class)->begin_use (brush);
+
+  for (i = 0; i < pipe->n_brushes; i++)
+    if (pipe->brushes[i])
+      gimp_brush_begin_use (pipe->brushes[i]);
+}
+
+static void
+gimp_brush_pipe_end_use (GimpBrush *brush)
+{
+  GimpBrushPipe *pipe = GIMP_BRUSH_PIPE (brush);
+  gint           i;
+
+  GIMP_BRUSH_CLASS (parent_class)->end_use (brush);
+
+  for (i = 0; i < pipe->n_brushes; i++)
+    if (pipe->brushes[i])
+      gimp_brush_end_use (pipe->brushes[i]);
+}
+
+static GimpBrush *
+gimp_brush_pipe_select_brush (GimpBrush        *brush,
+                              const GimpCoords *last_coords,
+                              const GimpCoords *current_coords)
+{
+  GimpBrushPipe *pipe = GIMP_BRUSH_PIPE (brush);
+  gint           i, brushix, ix;
+
+  if (pipe->n_brushes == 1)
+    return GIMP_BRUSH (pipe->current);
+
+  brushix = 0;
+  for (i = 0; i < pipe->dimension; i++)
+    {
+      switch (pipe->select[i])
+        {
+        case PIPE_SELECT_INCREMENTAL:
+          ix = (pipe->index[i] + 1) % pipe->rank[i];
+          break;
+
+        case PIPE_SELECT_ANGULAR:
+          /* Coords angle is already nomalized,
+           * offset by 90 degrees is still needed
+           * because hoses were made PS compatible*/
+          ix = (gint) RINT ((1.0 - current_coords->direction + 0.25) * pipe->rank[i]) % pipe->rank[i];
+          break;
+
+        case PIPE_SELECT_VELOCITY:
+          ix = ROUND (current_coords->velocity * pipe->rank[i]);
+          break;
+
+        case PIPE_SELECT_RANDOM:
+          /* This probably isn't the right way */
+          ix = g_random_int_range (0, pipe->rank[i]);
+          break;
+
+        case PIPE_SELECT_PRESSURE:
+          ix = RINT (current_coords->pressure * (pipe->rank[i] - 1));
+          break;
+
+        case PIPE_SELECT_TILT_X:
+          ix = RINT (current_coords->xtilt / 2.0 * pipe->rank[i]) + pipe->rank[i] / 2;
+          break;
+
+        case PIPE_SELECT_TILT_Y:
+          ix = RINT (current_coords->ytilt / 2.0 * pipe->rank[i]) + pipe->rank[i] / 2;
+          break;
+
+        case PIPE_SELECT_CONSTANT:
+        default:
+          ix = pipe->index[i];
+          break;
+        }
+
+      pipe->index[i] = CLAMP (ix, 0, pipe->rank[i] - 1);
+      brushix += pipe->stride[i] * pipe->index[i];
+    }
+
+  /* Make sure is inside bounds */
+  brushix = CLAMP (brushix, 0, pipe->n_brushes - 1);
+
+  pipe->current = pipe->brushes[brushix];
+
+  return GIMP_BRUSH (pipe->current);
+}
+
+static gboolean
+gimp_brush_pipe_want_null_motion (GimpBrush        *brush,
+                                  const GimpCoords *last_coords,
+                                  const GimpCoords *current_coords)
+{
+  GimpBrushPipe *pipe = GIMP_BRUSH_PIPE (brush);
+  gint           i;
+
+  if (pipe->n_brushes == 1)
+    return TRUE;
+
+  for (i = 0; i < pipe->dimension; i++)
+    if (pipe->select[i] == PIPE_SELECT_ANGULAR)
+      return FALSE;
+
+  return TRUE;
+}
+
+
+/*  public functions  */
+
+gboolean
+gimp_brush_pipe_set_params (GimpBrushPipe *pipe,
+                            const gchar   *paramstring)
+{
+  gint totalcells;
+  gint i;
+
+  g_return_val_if_fail (GIMP_IS_BRUSH_PIPE (pipe), FALSE);
+  g_return_val_if_fail (pipe->dimension == 0, FALSE); /* only on a new pipe! */
+
+  if (paramstring && *paramstring)
+    {
+      GimpPixPipeParams params;
+
+      gimp_pixpipe_params_init (&params);
+      gimp_pixpipe_params_parse (paramstring, &params);
+
+      pipe->dimension = params.dim;
+      pipe->rank      = g_new0 (gint, pipe->dimension);
+      pipe->select    = g_new0 (PipeSelectModes, pipe->dimension);
+      pipe->index     = g_new0 (gint, pipe->dimension);
+      /* placement is not used at all ?? */
+
+      for (i = 0; i < pipe->dimension; i++)
+        {
+          pipe->rank[i] = MAX (1, params.rank[i]);
+
+          if (strcmp (params.selection[i], "incremental") == 0)
+            pipe->select[i] = PIPE_SELECT_INCREMENTAL;
+          else if (strcmp (params.selection[i], "angular") == 0)
+            pipe->select[i] = PIPE_SELECT_ANGULAR;
+          else if (strcmp (params.selection[i], "velocity") == 0)
+            pipe->select[i] = PIPE_SELECT_VELOCITY;
+          else if (strcmp (params.selection[i], "random") == 0)
+            pipe->select[i] = PIPE_SELECT_RANDOM;
+          else if (strcmp (params.selection[i], "pressure") == 0)
+            pipe->select[i] = PIPE_SELECT_PRESSURE;
+          else if (strcmp (params.selection[i], "xtilt") == 0)
+            pipe->select[i] = PIPE_SELECT_TILT_X;
+          else if (strcmp (params.selection[i], "ytilt") == 0)
+            pipe->select[i] = PIPE_SELECT_TILT_Y;
+          else
+            pipe->select[i] = PIPE_SELECT_CONSTANT;
+
+          pipe->index[i] = 0;
+        }
+
+      gimp_pixpipe_params_free (&params);
+
+      pipe->params = g_strdup (paramstring);
+    }
+  else
+    {
+      pipe->dimension = 1;
+      pipe->rank      = g_new (gint, 1);
+      pipe->rank[0]   = pipe->n_brushes;
+      pipe->select    = g_new (PipeSelectModes, 1);
+      pipe->select[0] = PIPE_SELECT_INCREMENTAL;
+      pipe->index     = g_new (gint, 1);
+      pipe->index[0]  = 0;
+    }
+
+  totalcells = 1; /* Not all necessarily present, maybe */
+  for (i = 0; i < pipe->dimension; i++)
+    totalcells *= pipe->rank[i];
+
+  pipe->stride = g_new0 (gint, pipe->dimension);
+
+  for (i = 0; i < pipe->dimension; i++)
+    {
+      if (i == 0)
+        pipe->stride[i] = totalcells / pipe->rank[i];
+      else
+        pipe->stride[i] = pipe->stride[i-1] / pipe->rank[i];
+    }
+
+  if (pipe->stride[pipe->dimension - 1] != 1)
+    return FALSE;
+
+  return TRUE;
+}
diff --git a/app/core/gimpbrushpipe.h b/app/core/gimpbrushpipe.h
new file mode 100644
index 0000000..9615210
--- /dev/null
+++ b/app/core/gimpbrushpipe.h
@@ -0,0 +1,80 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ * Copyright (C) 1999 Adrian Likins and Tor Lillqvist
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_BRUSH_PIPE_H__
+#define __GIMP_BRUSH_PIPE_H__
+
+
+#include "gimpbrush.h"
+
+
+#define GIMP_TYPE_BRUSH_PIPE            (gimp_brush_pipe_get_type ())
+#define GIMP_BRUSH_PIPE(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_BRUSH_PIPE, GimpBrushPipe))
+#define GIMP_BRUSH_PIPE_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_BRUSH_PIPE, GimpBrushPipeClass))
+#define GIMP_IS_BRUSH_PIPE(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_BRUSH_PIPE))
+#define GIMP_IS_BRUSH_PIPE_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_BRUSH_PIPE))
+#define GIMP_BRUSH_PIPE_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_BRUSH_PIPE, GimpBrushPipeClass))
+
+
+typedef enum
+{
+  PIPE_SELECT_CONSTANT,
+  PIPE_SELECT_INCREMENTAL,
+  PIPE_SELECT_ANGULAR,
+  PIPE_SELECT_VELOCITY,
+  PIPE_SELECT_RANDOM,
+  PIPE_SELECT_PRESSURE,
+  PIPE_SELECT_TILT_X,
+  PIPE_SELECT_TILT_Y
+} PipeSelectModes;
+
+
+typedef struct _GimpBrushPipeClass GimpBrushPipeClass;
+
+struct _GimpBrushPipe
+{
+  GimpBrush         parent_instance;
+
+  gint              dimension;
+  gint             *rank;       /* Size in each dimension */
+  gint             *stride;     /* Aux for indexing */
+  PipeSelectModes  *select;     /* One mode per dimension */
+
+  gint             *index;      /* Current index for incremental dimensions */
+
+  gint              n_brushes;  /* Might be less than the product of the
+                                 * ranks in some odd special case */
+  GimpBrush       **brushes;
+  GimpBrush        *current;    /* Currently selected brush */
+
+  gchar            *params;     /* For pipe <-> image conversion */
+};
+
+struct _GimpBrushPipeClass
+{
+  GimpBrushClass  parent_class;
+};
+
+
+GType      gimp_brush_pipe_get_type   (void) G_GNUC_CONST;
+
+gboolean   gimp_brush_pipe_set_params (GimpBrushPipe *pipe,
+                                       const gchar   *paramstring);
+
+
+#endif  /* __GIMP_BRUSH_PIPE_H__ */
diff --git a/app/core/gimpbuffer.c b/app/core/gimpbuffer.c
new file mode 100644
index 0000000..c713ed8
--- /dev/null
+++ b/app/core/gimpbuffer.c
@@ -0,0 +1,541 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <cairo.h>
+#include <gegl.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpcolor/gimpcolor.h"
+
+#include "core-types.h"
+
+#include "gegl/gimp-babl.h"
+#include "gegl/gimp-gegl-loops.h"
+#include "gegl/gimp-gegl-utils.h"
+
+#include "gimp-memsize.h"
+#include "gimpbuffer.h"
+#include "gimpimage.h"
+#include "gimptempbuf.h"
+
+
+static void          gimp_color_managed_iface_init (GimpColorManagedInterface *iface);
+
+static void          gimp_buffer_finalize          (GObject           *object);
+
+static gint64        gimp_buffer_get_memsize       (GimpObject        *object,
+                                                    gint64            *gui_size);
+
+static gboolean      gimp_buffer_get_size          (GimpViewable      *viewable,
+                                                    gint              *width,
+                                                    gint              *height);
+static void          gimp_buffer_get_preview_size  (GimpViewable      *viewable,
+                                                    gint               size,
+                                                    gboolean           is_popup,
+                                                    gboolean           dot_for_dot,
+                                                    gint              *popup_width,
+                                                    gint              *popup_height);
+static gboolean      gimp_buffer_get_popup_size    (GimpViewable      *viewable,
+                                                    gint               width,
+                                                    gint               height,
+                                                    gboolean           dot_for_dot,
+                                                    gint              *popup_width,
+                                                    gint              *popup_height);
+static GimpTempBuf * gimp_buffer_get_new_preview   (GimpViewable      *viewable,
+                                                    GimpContext       *context,
+                                                    gint               width,
+                                                    gint               height);
+static GdkPixbuf   * gimp_buffer_get_new_pixbuf    (GimpViewable      *viewable,
+                                                    GimpContext       *context,
+                                                    gint               width,
+                                                    gint               height);
+static gchar       * gimp_buffer_get_description   (GimpViewable      *viewable,
+                                                    gchar            **tooltip);
+
+static const guint8 *
+       gimp_buffer_color_managed_get_icc_profile   (GimpColorManaged  *managed,
+                                                    gsize             *len);
+static GimpColorProfile *
+       gimp_buffer_color_managed_get_color_profile (GimpColorManaged  *managed);
+static void
+       gimp_buffer_color_managed_profile_changed   (GimpColorManaged  *managed);
+
+
+G_DEFINE_TYPE_WITH_CODE (GimpBuffer, gimp_buffer, GIMP_TYPE_VIEWABLE,
+                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_COLOR_MANAGED,
+                                                gimp_color_managed_iface_init))
+
+#define parent_class gimp_buffer_parent_class
+
+
+static void
+gimp_buffer_class_init (GimpBufferClass *klass)
+{
+  GObjectClass      *object_class      = G_OBJECT_CLASS (klass);
+  GimpObjectClass   *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+  GimpViewableClass *viewable_class    = GIMP_VIEWABLE_CLASS (klass);
+
+  object_class->finalize            = gimp_buffer_finalize;
+
+  gimp_object_class->get_memsize    = gimp_buffer_get_memsize;
+
+  viewable_class->default_icon_name = "edit-paste";
+  viewable_class->name_editable     = TRUE;
+  viewable_class->get_size          = gimp_buffer_get_size;
+  viewable_class->get_preview_size  = gimp_buffer_get_preview_size;
+  viewable_class->get_popup_size    = gimp_buffer_get_popup_size;
+  viewable_class->get_new_preview   = gimp_buffer_get_new_preview;
+  viewable_class->get_new_pixbuf    = gimp_buffer_get_new_pixbuf;
+  viewable_class->get_description   = gimp_buffer_get_description;
+}
+
+static void
+gimp_color_managed_iface_init (GimpColorManagedInterface *iface)
+{
+  iface->get_icc_profile   = gimp_buffer_color_managed_get_icc_profile;
+  iface->get_color_profile = gimp_buffer_color_managed_get_color_profile;
+  iface->profile_changed   = gimp_buffer_color_managed_profile_changed;
+}
+
+static void
+gimp_buffer_init (GimpBuffer *buffer)
+{
+}
+
+static void
+gimp_buffer_finalize (GObject *object)
+{
+  GimpBuffer *buffer = GIMP_BUFFER (object);
+
+  g_clear_object (&buffer->buffer);
+
+  gimp_buffer_set_color_profile (buffer, NULL);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static gint64
+gimp_buffer_get_memsize (GimpObject *object,
+                         gint64     *gui_size)
+{
+  GimpBuffer *buffer  = GIMP_BUFFER (object);
+  gint64      memsize = 0;
+
+  memsize += gimp_gegl_buffer_get_memsize (buffer->buffer);
+  memsize += gimp_g_object_get_memsize (G_OBJECT (buffer->color_profile));
+
+  return memsize + GIMP_OBJECT_CLASS (parent_class)->get_memsize (object,
+                                                                  gui_size);
+}
+
+static gboolean
+gimp_buffer_get_size (GimpViewable *viewable,
+                      gint         *width,
+                      gint         *height)
+{
+  GimpBuffer *buffer = GIMP_BUFFER (viewable);
+
+  *width  = gimp_buffer_get_width (buffer);
+  *height = gimp_buffer_get_height (buffer);
+
+  return TRUE;
+}
+
+static void
+gimp_buffer_get_preview_size (GimpViewable *viewable,
+                              gint          size,
+                              gboolean      is_popup,
+                              gboolean      dot_for_dot,
+                              gint         *width,
+                              gint         *height)
+{
+  GimpBuffer *buffer = GIMP_BUFFER (viewable);
+
+  gimp_viewable_calc_preview_size (gimp_buffer_get_width (buffer),
+                                   gimp_buffer_get_height (buffer),
+                                   size,
+                                   size,
+                                   dot_for_dot, 1.0, 1.0,
+                                   width,
+                                   height,
+                                   NULL);
+}
+
+static gboolean
+gimp_buffer_get_popup_size (GimpViewable *viewable,
+                            gint          width,
+                            gint          height,
+                            gboolean      dot_for_dot,
+                            gint         *popup_width,
+                            gint         *popup_height)
+{
+  GimpBuffer *buffer;
+  gint        buffer_width;
+  gint        buffer_height;
+
+  buffer        = GIMP_BUFFER (viewable);
+  buffer_width  = gimp_buffer_get_width (buffer);
+  buffer_height = gimp_buffer_get_height (buffer);
+
+  if (buffer_width > width || buffer_height > height)
+    {
+      gboolean scaling_up;
+
+      gimp_viewable_calc_preview_size (buffer_width,
+                                       buffer_height,
+                                       width  * 2,
+                                       height * 2,
+                                       dot_for_dot, 1.0, 1.0,
+                                       popup_width,
+                                       popup_height,
+                                       &scaling_up);
+
+      if (scaling_up)
+        {
+          *popup_width  = buffer_width;
+          *popup_height = buffer_height;
+        }
+
+      return TRUE;
+    }
+
+  return FALSE;
+}
+
+static GimpTempBuf *
+gimp_buffer_get_new_preview (GimpViewable *viewable,
+                             GimpContext  *context,
+                             gint          width,
+                             gint          height)
+{
+  GimpBuffer  *buffer = GIMP_BUFFER (viewable);
+  const Babl  *format = gimp_buffer_get_format (buffer);
+  GimpTempBuf *preview;
+
+  if (babl_format_is_palette (format))
+    format = gimp_babl_format (GIMP_RGB, GIMP_PRECISION_U8_GAMMA,
+                               babl_format_has_alpha (format));
+  else
+    format = gimp_babl_format (gimp_babl_format_get_base_type (format),
+                               gimp_babl_precision (GIMP_COMPONENT_TYPE_U8,
+                                                    gimp_babl_format_get_linear (format)),
+                               babl_format_has_alpha (format));
+
+  preview = gimp_temp_buf_new (width, height, format);
+
+  gegl_buffer_get (buffer->buffer, GEGL_RECTANGLE (0, 0, width, height),
+                   MIN ((gdouble) width  / (gdouble) gimp_buffer_get_width (buffer),
+                        (gdouble) height / (gdouble) gimp_buffer_get_height (buffer)),
+                   format,
+                   gimp_temp_buf_get_data (preview),
+                   GEGL_AUTO_ROWSTRIDE, GEGL_ABYSS_NONE);
+
+  return preview;
+}
+
+static GdkPixbuf *
+gimp_buffer_get_new_pixbuf (GimpViewable *viewable,
+                            GimpContext  *context,
+                            gint          width,
+                            gint          height)
+{
+  GimpBuffer *buffer = GIMP_BUFFER (viewable);
+  GdkPixbuf  *pixbuf;
+  gdouble     scale;
+
+  pixbuf = gdk_pixbuf_new (GDK_COLORSPACE_RGB, TRUE, 8,
+                           width, height);
+
+  scale = MIN ((gdouble) width  / (gdouble) gimp_buffer_get_width (buffer),
+               (gdouble) height / (gdouble) gimp_buffer_get_height (buffer));
+
+  if (buffer->color_profile)
+    {
+      GimpColorProfile *srgb_profile;
+      GimpTempBuf      *temp_buf;
+      GeglBuffer       *src_buf;
+      GeglBuffer       *dest_buf;
+
+      srgb_profile = gimp_color_profile_new_rgb_srgb ();
+
+      temp_buf = gimp_temp_buf_new (width, height,
+                                    gimp_buffer_get_format (buffer));
+
+      gegl_buffer_get (buffer->buffer,
+                       GEGL_RECTANGLE (0, 0, width, height),
+                       scale,
+                       gimp_temp_buf_get_format (temp_buf),
+                       gimp_temp_buf_get_data (temp_buf),
+                       GEGL_AUTO_ROWSTRIDE, GEGL_ABYSS_CLAMP);
+
+      src_buf  = gimp_temp_buf_create_buffer (temp_buf);
+      dest_buf = gimp_pixbuf_create_buffer (pixbuf);
+
+      gimp_temp_buf_unref (temp_buf);
+
+      gimp_gegl_convert_color_profile (src_buf,
+                                       GEGL_RECTANGLE (0, 0, width, height),
+                                       buffer->color_profile,
+                                       dest_buf,
+                                       GEGL_RECTANGLE (0, 0, 0, 0),
+                                       srgb_profile,
+                                       GIMP_COLOR_RENDERING_INTENT_PERCEPTUAL,
+                                       TRUE,
+                                       NULL);
+
+      g_object_unref (src_buf);
+      g_object_unref (dest_buf);
+
+      g_object_unref (srgb_profile);
+    }
+  else
+    {
+      gegl_buffer_get (buffer->buffer,
+                       GEGL_RECTANGLE (0, 0, width, height),
+                       scale,
+                       gimp_pixbuf_get_format (pixbuf),
+                       gdk_pixbuf_get_pixels (pixbuf),
+                       gdk_pixbuf_get_rowstride (pixbuf),
+                       GEGL_ABYSS_CLAMP);
+    }
+
+  return pixbuf;
+}
+
+static gchar *
+gimp_buffer_get_description (GimpViewable  *viewable,
+                             gchar        **tooltip)
+{
+  GimpBuffer *buffer = GIMP_BUFFER (viewable);
+
+  return g_strdup_printf ("%s (%d × %d)",
+                          gimp_object_get_name (buffer),
+                          gimp_buffer_get_width (buffer),
+                          gimp_buffer_get_height (buffer));
+}
+
+static const guint8 *
+gimp_buffer_color_managed_get_icc_profile (GimpColorManaged *managed,
+                             gsize            *len)
+{
+  GimpBuffer *buffer = GIMP_BUFFER (managed);
+
+  if (buffer->color_profile)
+    return gimp_color_profile_get_icc_profile (buffer->color_profile, len);
+
+  return NULL;
+}
+
+static GimpColorProfile *
+gimp_buffer_color_managed_get_color_profile (GimpColorManaged *managed)
+{
+  GimpBuffer *buffer = GIMP_BUFFER (managed);
+
+  if (buffer->color_profile)
+    return buffer->color_profile;
+
+  return gimp_babl_format_get_color_profile (gimp_buffer_get_format (buffer));
+}
+
+static void
+gimp_buffer_color_managed_profile_changed (GimpColorManaged *managed)
+{
+  gimp_viewable_invalidate_preview (GIMP_VIEWABLE (managed));
+}
+
+
+/*  public functions  */
+
+GimpBuffer *
+gimp_buffer_new (GeglBuffer    *buffer,
+                 const gchar   *name,
+                 gint           offset_x,
+                 gint           offset_y,
+                 gboolean       copy_pixels)
+{
+  GimpBuffer *gimp_buffer;
+
+  g_return_val_if_fail (GEGL_IS_BUFFER (buffer), NULL);
+  g_return_val_if_fail (name != NULL, NULL);
+
+  gimp_buffer = g_object_new (GIMP_TYPE_BUFFER,
+                              "name", name,
+                              NULL);
+
+  if (copy_pixels)
+    gimp_buffer->buffer = gimp_gegl_buffer_dup (buffer);
+  else
+    gimp_buffer->buffer = g_object_ref (buffer);
+
+  gimp_buffer->offset_x = offset_x;
+  gimp_buffer->offset_y = offset_y;
+
+  return gimp_buffer;
+}
+
+GimpBuffer *
+gimp_buffer_new_from_pixbuf (GdkPixbuf   *pixbuf,
+                             const gchar *name,
+                             gint         offset_x,
+                             gint         offset_y)
+{
+  GimpBuffer       *gimp_buffer;
+  GeglBuffer       *buffer;
+  guint8           *icc_data;
+  gsize             icc_len;
+  GimpColorProfile *profile = NULL;
+
+  g_return_val_if_fail (GDK_IS_PIXBUF (pixbuf), NULL);
+  g_return_val_if_fail (name != NULL, NULL);
+
+  buffer = gimp_pixbuf_create_buffer (pixbuf);
+
+  gimp_buffer = gimp_buffer_new (buffer, name,
+                                 offset_x, offset_y, FALSE);
+
+  icc_data = gimp_pixbuf_get_icc_profile (pixbuf, &icc_len);
+  if (icc_data)
+    {
+      profile = gimp_color_profile_new_from_icc_profile (icc_data, icc_len,
+                                                         NULL);
+      g_free (icc_data);
+    }
+
+  if (! profile && gdk_pixbuf_get_colorspace (pixbuf) == GDK_COLORSPACE_RGB)
+    {
+      profile = gimp_color_profile_new_rgb_srgb ();
+    }
+
+  if (profile)
+    {
+      gimp_buffer_set_color_profile (gimp_buffer, profile);
+      g_object_unref (profile);
+    }
+
+  g_object_unref (buffer);
+
+  return gimp_buffer;
+}
+
+gint
+gimp_buffer_get_width (GimpBuffer *buffer)
+{
+  g_return_val_if_fail (GIMP_IS_BUFFER (buffer), 0);
+
+  return gegl_buffer_get_width (buffer->buffer);
+}
+
+gint
+gimp_buffer_get_height (GimpBuffer *buffer)
+{
+  g_return_val_if_fail (GIMP_IS_BUFFER (buffer), 0);
+
+  return gegl_buffer_get_height (buffer->buffer);
+}
+
+const Babl *
+gimp_buffer_get_format (GimpBuffer *buffer)
+{
+  g_return_val_if_fail (GIMP_IS_BUFFER (buffer), NULL);
+
+  return gegl_buffer_get_format (buffer->buffer);
+}
+
+GeglBuffer *
+gimp_buffer_get_buffer (GimpBuffer *buffer)
+{
+  g_return_val_if_fail (GIMP_IS_BUFFER (buffer), NULL);
+
+  return buffer->buffer;
+}
+
+void
+gimp_buffer_set_resolution (GimpBuffer *buffer,
+                            gdouble     resolution_x,
+                            gdouble     resolution_y)
+{
+  g_return_if_fail (GIMP_IS_BUFFER (buffer));
+  g_return_if_fail (resolution_x >= 0.0 && resolution_x <= GIMP_MAX_RESOLUTION);
+  g_return_if_fail (resolution_y >= 0.0 && resolution_y <= GIMP_MAX_RESOLUTION);
+
+  buffer->resolution_x = resolution_x;
+  buffer->resolution_y = resolution_y;
+}
+
+gboolean
+gimp_buffer_get_resolution (GimpBuffer *buffer,
+                            gdouble    *resolution_x,
+                            gdouble    *resolution_y)
+{
+  g_return_val_if_fail (GIMP_IS_BUFFER (buffer), FALSE);
+
+  if (buffer->resolution_x > 0.0 &&
+      buffer->resolution_y > 0.0)
+    {
+      if (resolution_x) *resolution_x = buffer->resolution_x;
+      if (resolution_y) *resolution_y = buffer->resolution_y;
+
+      return TRUE;
+    }
+
+  return FALSE;
+}
+
+void
+gimp_buffer_set_unit (GimpBuffer *buffer,
+                      GimpUnit    unit)
+{
+  g_return_if_fail (GIMP_IS_BUFFER (buffer));
+  g_return_if_fail (unit > GIMP_UNIT_PIXEL);
+
+  buffer->unit = unit;
+}
+
+GimpUnit
+gimp_buffer_get_unit (GimpBuffer *buffer)
+{
+  g_return_val_if_fail (GIMP_IS_BUFFER (buffer), GIMP_UNIT_PIXEL);
+
+  return buffer->unit;
+}
+
+void
+gimp_buffer_set_color_profile (GimpBuffer       *buffer,
+                               GimpColorProfile *profile)
+{
+  g_return_if_fail (GIMP_IS_BUFFER (buffer));
+  g_return_if_fail (profile == NULL || GIMP_IS_COLOR_PROFILE (profile));
+
+  if (profile != buffer->color_profile)
+    {
+      g_clear_object (&buffer->color_profile);
+
+      if (profile)
+        buffer->color_profile = g_object_ref (profile);
+    }
+}
+
+GimpColorProfile *
+gimp_buffer_get_color_profile (GimpBuffer *buffer)
+{
+  g_return_val_if_fail (GIMP_IS_BUFFER (buffer), NULL);
+
+  return buffer->color_profile;
+}
diff --git a/app/core/gimpbuffer.h b/app/core/gimpbuffer.h
new file mode 100644
index 0000000..2949bae
--- /dev/null
+++ b/app/core/gimpbuffer.h
@@ -0,0 +1,90 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_BUFFER_H__
+#define __GIMP_BUFFER_H__
+
+
+#include "gimpviewable.h"
+
+
+#define GIMP_TYPE_BUFFER            (gimp_buffer_get_type ())
+#define GIMP_BUFFER(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_BUFFER, GimpBuffer))
+#define GIMP_BUFFER_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_BUFFER, GimpBufferClass))
+#define GIMP_IS_BUFFER(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_BUFFER))
+#define GIMP_IS_BUFFER_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_BUFFER))
+#define GIMP_BUFFER_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_BUFFER, GimpBufferClass))
+
+
+typedef struct _GimpBufferClass GimpBufferClass;
+
+struct _GimpBuffer
+{
+  GimpViewable      parent_instance;
+
+  GeglBuffer       *buffer;
+  gint              offset_x;
+  gint              offset_y;
+
+  gdouble           resolution_x;
+  gdouble           resolution_y;
+  GimpUnit          unit;
+
+  GimpColorProfile *color_profile;
+};
+
+struct _GimpBufferClass
+{
+  GimpViewableClass  parent_class;
+};
+
+
+GType              gimp_buffer_get_type          (void) G_GNUC_CONST;
+
+GimpBuffer       * gimp_buffer_new               (GeglBuffer       *buffer,
+                                                  const gchar      *name,
+                                                  gint              offset_x,
+                                                  gint              offset_y,
+                                                  gboolean          copy_pixels);
+GimpBuffer       * gimp_buffer_new_from_pixbuf   (GdkPixbuf        *pixbuf,
+                                                  const gchar      *name,
+                                                  gint              offset_x,
+                                                  gint              offset_y);
+
+gint               gimp_buffer_get_width         (GimpBuffer       *buffer);
+gint               gimp_buffer_get_height        (GimpBuffer       *buffer);
+const Babl       * gimp_buffer_get_format        (GimpBuffer       *buffer);
+
+GeglBuffer       * gimp_buffer_get_buffer        (GimpBuffer       *buffer);
+
+void               gimp_buffer_set_resolution    (GimpBuffer       *buffer,
+                                                  gdouble           resolution_x,
+                                                  gdouble           resolution_y);
+gboolean           gimp_buffer_get_resolution    (GimpBuffer       *buffer,
+                                                  gdouble          *resolution_x,
+                                                  gdouble          *resolution_y);
+
+void               gimp_buffer_set_unit          (GimpBuffer       *buffer,
+                                                  GimpUnit          unit);
+GimpUnit           gimp_buffer_get_unit          (GimpBuffer       *buffer);
+
+void               gimp_buffer_set_color_profile (GimpBuffer       *buffer,
+                                                  GimpColorProfile *profile);
+GimpColorProfile * gimp_buffer_get_color_profile (GimpBuffer       *buffer);
+
+
+#endif /* __GIMP_BUFFER_H__ */
diff --git a/app/core/gimpcancelable.c b/app/core/gimpcancelable.c
new file mode 100644
index 0000000..9cb5f12
--- /dev/null
+++ b/app/core/gimpcancelable.c
@@ -0,0 +1,72 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpcancelable.c
+ * Copyright (C) 2018 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gimpcancelable.h"
+#include "gimpmarshal.h"
+
+
+enum
+{
+  CANCEL,
+  LAST_SIGNAL
+};
+
+
+G_DEFINE_INTERFACE (GimpCancelable, gimp_cancelable, G_TYPE_OBJECT)
+
+
+static guint cancelable_signals[LAST_SIGNAL] = { 0 };
+
+
+/*  private functions  */
+
+
+static void
+gimp_cancelable_default_init (GimpCancelableInterface *iface)
+{
+  cancelable_signals[CANCEL] =
+    g_signal_new ("cancel",
+                  G_TYPE_FROM_CLASS (iface),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpCancelableInterface, cancel),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+}
+
+
+/*  public functions  */
+
+
+void
+gimp_cancelable_cancel (GimpCancelable *cancelable)
+{
+  g_return_if_fail (GIMP_IS_CANCELABLE (cancelable));
+
+  g_signal_emit (cancelable, cancelable_signals[CANCEL], 0);
+}
diff --git a/app/core/gimpcancelable.h b/app/core/gimpcancelable.h
new file mode 100644
index 0000000..dc2a655
--- /dev/null
+++ b/app/core/gimpcancelable.h
@@ -0,0 +1,47 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1997 Spencer Kimball and Peter Mattis
+ *
+ * gimpcancelable.h
+ * Copyright (C) 2018 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_CANCELABLE_H__
+#define __GIMP_CANCELABLE_H__
+
+
+#define GIMP_TYPE_CANCELABLE               (gimp_cancelable_get_type ())
+#define GIMP_IS_CANCELABLE(obj)            (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_CANCELABLE))
+#define GIMP_CANCELABLE(obj)               (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_CANCELABLE, GimpCancelable))
+#define GIMP_CANCELABLE_GET_INTERFACE(obj) (G_TYPE_INSTANCE_GET_INTERFACE ((obj), GIMP_TYPE_CANCELABLE, GimpCancelableInterface))
+
+
+typedef struct _GimpCancelableInterface GimpCancelableInterface;
+
+struct _GimpCancelableInterface
+{
+  GTypeInterface base_iface;
+
+  /*  signals  */
+  void   (* cancel) (GimpCancelable *cancelable);
+};
+
+
+GType   gimp_cancelable_get_type (void) G_GNUC_CONST;
+
+void    gimp_cancelable_cancel   (GimpCancelable *cancelable);
+
+
+#endif  /* __GIMP_CANCELABLE_H__ */
diff --git a/app/core/gimpchannel-combine.c b/app/core/gimpchannel-combine.c
new file mode 100644
index 0000000..8326f65
--- /dev/null
+++ b/app/core/gimpchannel-combine.c
@@ -0,0 +1,471 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpmath/gimpmath.h"
+
+#include "core-types.h"
+
+#include "gegl/gimp-gegl-mask-combine.h"
+
+#include "gimpchannel.h"
+#include "gimpchannel-combine.h"
+
+
+typedef struct
+{
+  GeglRectangle rect;
+
+  gboolean      bounds_known;
+  gboolean      empty;
+  GeglRectangle bounds;
+} GimpChannelCombineData;
+
+
+/*  local function prototypes  */
+
+static void       gimp_channel_combine_clear            (GimpChannel            *mask,
+                                                         const GeglRectangle    *rect);
+static void       gimp_channel_combine_clear_complement (GimpChannel            *mask,
+                                                         const GeglRectangle    *rect);
+
+static gboolean   gimp_channel_combine_start            (GimpChannel            *mask,
+                                                         GimpChannelOps          op,
+                                                         const GeglRectangle    *rect,
+                                                         gboolean                full_extent,
+                                                         gboolean                full_value,
+                                                         GimpChannelCombineData *data);
+static void       gimp_channel_combine_end              (GimpChannel            *mask,
+                                                         GimpChannelCombineData *data);
+
+
+/*  private functions  */
+
+static void
+gimp_channel_combine_clear (GimpChannel         *mask,
+                            const GeglRectangle *rect)
+{
+  GeglBuffer    *buffer;
+  GeglRectangle  area;
+  GeglRectangle  update_area;
+
+  if (mask->bounds_known && mask->empty)
+    return;
+
+  buffer = gimp_drawable_get_buffer (GIMP_DRAWABLE (mask));
+
+  if (rect)
+    {
+      if (rect->width <= 0 || rect->height <= 0)
+        return;
+
+      if (mask->bounds_known)
+        {
+          if (! gegl_rectangle_intersect (&area,
+                                          GEGL_RECTANGLE (mask->x1,
+                                                          mask->y1,
+                                                          mask->x2 - mask->x1,
+                                                          mask->y2 - mask->y1),
+                                          rect))
+            {
+              return;
+            }
+        }
+      else
+        {
+          area = *rect;
+        }
+
+      update_area = area;
+    }
+  else
+    {
+      if (mask->bounds_known)
+        {
+          area.x      = mask->x1;
+          area.y      = mask->y1;
+          area.width  = mask->x2 - mask->x1;
+          area.height = mask->y2 - mask->y1;
+        }
+      else
+        {
+          area.x      = 0;
+          area.y      = 0;
+          area.width  = gimp_item_get_width  (GIMP_ITEM (mask));
+          area.height = gimp_item_get_height (GIMP_ITEM (mask));
+        }
+
+      update_area = area;
+
+      gegl_rectangle_align_to_buffer (&area, &area, buffer,
+                                      GEGL_RECTANGLE_ALIGNMENT_SUPERSET);
+    }
+
+  gegl_buffer_clear (buffer, &area);
+
+  gimp_drawable_update (GIMP_DRAWABLE (mask),
+                        update_area.x, update_area.y,
+                        update_area.width, update_area.height);
+}
+
+static void
+gimp_channel_combine_clear_complement (GimpChannel         *mask,
+                                       const GeglRectangle *rect)
+{
+  gint width  = gimp_item_get_width  (GIMP_ITEM (mask));
+  gint height = gimp_item_get_height (GIMP_ITEM (mask));
+
+  gimp_channel_combine_clear (
+    mask,
+    GEGL_RECTANGLE (0,
+                    0,
+                    width,
+                    rect->y));
+
+  gimp_channel_combine_clear (
+    mask,
+    GEGL_RECTANGLE (0,
+                    rect->y + rect->height,
+                    width,
+                    height - (rect->y + rect->height)));
+
+  gimp_channel_combine_clear (
+    mask,
+    GEGL_RECTANGLE (0,
+                    rect->y,
+                    rect->x,
+                    rect->height));
+
+  gimp_channel_combine_clear (
+    mask,
+    GEGL_RECTANGLE (rect->x + rect->width,
+                    rect->y,
+                    width - (rect->x + rect->width),
+                    rect->height));
+}
+
+static gboolean
+gimp_channel_combine_start (GimpChannel            *mask,
+                            GimpChannelOps          op,
+                            const GeglRectangle    *rect,
+                            gboolean                full_extent,
+                            gboolean                full_value,
+                            GimpChannelCombineData *data)
+{
+  GeglBuffer    *buffer = gimp_drawable_get_buffer (GIMP_DRAWABLE (mask));
+  GeglRectangle  extent;
+  gboolean       intersects;
+
+  extent.x      = 0;
+  extent.y      = 0;
+  extent.width  = gimp_item_get_width  (GIMP_ITEM (mask));
+  extent.height = gimp_item_get_height (GIMP_ITEM (mask));
+
+  intersects = gegl_rectangle_intersect (&data->rect, rect, &extent);
+
+  data->bounds_known  = mask->bounds_known;
+  data->empty         = mask->empty;
+
+  data->bounds.x      = mask->x1;
+  data->bounds.y      = mask->y1;
+  data->bounds.width  = mask->x2 - mask->x1;
+  data->bounds.height = mask->y2 - mask->y1;
+
+  gegl_buffer_freeze_changed (buffer);
+
+  /*  Determine new boundary  */
+  switch (op)
+    {
+    case GIMP_CHANNEL_OP_REPLACE:
+      gimp_channel_combine_clear (mask, NULL);
+
+      if (! intersects)
+        {
+          data->bounds_known = TRUE;
+          data->empty        = TRUE;
+
+          return FALSE;
+        }
+
+      data->bounds_known = FALSE;
+
+      if (full_extent)
+        {
+          data->bounds_known = TRUE;
+          data->empty        = FALSE;
+          data->bounds       = data->rect;
+        }
+      break;
+
+    case GIMP_CHANNEL_OP_ADD:
+      if (! intersects)
+        return FALSE;
+
+      data->bounds_known = FALSE;
+
+      if (full_extent && (mask->bounds_known ||
+                          gegl_rectangle_equal (&data->rect, &extent)))
+        {
+          data->bounds_known = TRUE;
+          data->empty        = FALSE;
+
+          if (mask->bounds_known && ! mask->empty)
+            {
+              gegl_rectangle_bounding_box (&data->bounds,
+                                           &data->bounds, &data->rect);
+            }
+          else
+            {
+              data->bounds = data->rect;
+            }
+        }
+      break;
+
+    case GIMP_CHANNEL_OP_SUBTRACT:
+      if (intersects && mask->bounds_known)
+        {
+          if (mask->empty)
+            {
+              intersects = FALSE;
+            }
+          else
+            {
+              intersects = gegl_rectangle_intersect (&data->rect,
+                                                     &data->rect,
+                                                     &data->bounds);
+            }
+        }
+
+      if (! intersects)
+        return FALSE;
+
+      if (full_value &&
+          gegl_rectangle_contains (&data->rect,
+                                   mask->bounds_known ? &data->bounds :
+                                                        &extent))
+        {
+          gimp_channel_combine_clear (mask, NULL);
+
+          data->bounds_known = TRUE;
+          data->empty        = TRUE;
+
+          return FALSE;
+        }
+
+      data->bounds_known = FALSE;
+
+      gegl_buffer_set_abyss (buffer, &data->rect);
+      break;
+
+    case GIMP_CHANNEL_OP_INTERSECT:
+      if (intersects && mask->bounds_known)
+        {
+          if (mask->empty)
+            {
+              intersects = FALSE;
+            }
+          else
+            {
+              intersects = gegl_rectangle_intersect (&data->rect,
+                                                     &data->rect,
+                                                     &data->bounds);
+            }
+        }
+
+      if (! intersects)
+        {
+          gimp_channel_combine_clear (mask, NULL);
+
+          data->bounds_known = TRUE;
+          data->empty        = TRUE;
+
+          return FALSE;
+        }
+
+      if (full_value && mask->bounds_known &&
+          gegl_rectangle_contains (&data->rect, &data->bounds))
+        {
+          return FALSE;
+        }
+
+      data->bounds_known = FALSE;
+
+      gimp_channel_combine_clear_complement (mask, &data->rect);
+
+      gegl_buffer_set_abyss (buffer, &data->rect);
+      break;
+    }
+
+  return TRUE;
+}
+
+static void
+gimp_channel_combine_end (GimpChannel            *mask,
+                          GimpChannelCombineData *data)
+{
+  GeglBuffer *buffer = gimp_drawable_get_buffer (GIMP_DRAWABLE (mask));
+
+  gegl_buffer_set_abyss (buffer, gegl_buffer_get_extent (buffer));
+
+  gegl_buffer_thaw_changed (buffer);
+
+  mask->bounds_known = data->bounds_known;
+
+  if (data->bounds_known)
+    {
+      mask->empty = data->empty;
+
+      if (data->empty)
+        {
+          mask->x1 = 0;
+          mask->y1 = 0;
+          mask->x2 = gimp_item_get_width  (GIMP_ITEM (mask));
+          mask->y2 = gimp_item_get_height (GIMP_ITEM (mask));
+        }
+      else
+        {
+          mask->x1 = data->bounds.x;
+          mask->y1 = data->bounds.y;
+          mask->x2 = data->bounds.x + data->bounds.width;
+          mask->y2 = data->bounds.y + data->bounds.height;
+        }
+    }
+
+  gimp_drawable_update (GIMP_DRAWABLE (mask),
+                        data->rect.x, data->rect.y,
+                        data->rect.width, data->rect.height);
+}
+
+
+/*  public functions  */
+
+void
+gimp_channel_combine_rect (GimpChannel    *mask,
+                           GimpChannelOps  op,
+                           gint            x,
+                           gint            y,
+                           gint            w,
+                           gint            h)
+{
+  GimpChannelCombineData data;
+
+  g_return_if_fail (GIMP_IS_CHANNEL (mask));
+
+  if (gimp_channel_combine_start (mask, op, GEGL_RECTANGLE (x, y, w, h),
+                                  TRUE, TRUE, &data))
+    {
+      GeglBuffer *buffer = gimp_drawable_get_buffer (GIMP_DRAWABLE (mask));
+
+      gimp_gegl_mask_combine_rect (buffer, op, x, y, w, h);
+    }
+
+  gimp_channel_combine_end (mask, &data);
+}
+
+void
+gimp_channel_combine_ellipse (GimpChannel    *mask,
+                              GimpChannelOps  op,
+                              gint            x,
+                              gint            y,
+                              gint            w,
+                              gint            h,
+                              gboolean        antialias)
+{
+  gimp_channel_combine_ellipse_rect (mask, op, x, y, w, h,
+                                     w / 2.0, h / 2.0, antialias);
+}
+
+void
+gimp_channel_combine_ellipse_rect (GimpChannel    *mask,
+                                   GimpChannelOps  op,
+                                   gint            x,
+                                   gint            y,
+                                   gint            w,
+                                   gint            h,
+                                   gdouble         rx,
+                                   gdouble         ry,
+                                   gboolean        antialias)
+{
+  GimpChannelCombineData data;
+
+  g_return_if_fail (GIMP_IS_CHANNEL (mask));
+
+  if (gimp_channel_combine_start (mask, op, GEGL_RECTANGLE (x, y, w, h),
+                                  TRUE, FALSE, &data))
+    {
+      GeglBuffer *buffer = gimp_drawable_get_buffer (GIMP_DRAWABLE (mask));
+
+      gimp_gegl_mask_combine_ellipse_rect (buffer, op, x, y, w, h,
+                                           rx, ry, antialias);
+    }
+
+  gimp_channel_combine_end (mask, &data);
+}
+
+void
+gimp_channel_combine_mask (GimpChannel    *mask,
+                           GimpChannel    *add_on,
+                           GimpChannelOps  op,
+                           gint            off_x,
+                           gint            off_y)
+{
+  GeglBuffer *add_on_buffer;
+
+  g_return_if_fail (GIMP_IS_CHANNEL (mask));
+  g_return_if_fail (GIMP_IS_CHANNEL (add_on));
+
+  add_on_buffer = gimp_drawable_get_buffer (GIMP_DRAWABLE (add_on));
+
+  gimp_channel_combine_buffer (mask, add_on_buffer,
+                               op, off_x, off_y);
+}
+
+void
+gimp_channel_combine_buffer (GimpChannel    *mask,
+                             GeglBuffer     *add_on_buffer,
+                             GimpChannelOps  op,
+                             gint            off_x,
+                             gint            off_y)
+{
+  GimpChannelCombineData data;
+
+  g_return_if_fail (GIMP_IS_CHANNEL (mask));
+  g_return_if_fail (GEGL_IS_BUFFER (add_on_buffer));
+
+  if (gimp_channel_combine_start (mask, op,
+                                  GEGL_RECTANGLE (
+                                    off_x + gegl_buffer_get_x (add_on_buffer),
+                                    off_y + gegl_buffer_get_y (add_on_buffer),
+                                    gegl_buffer_get_width  (add_on_buffer),
+                                    gegl_buffer_get_height (add_on_buffer)),
+                                  FALSE, FALSE, &data))
+    {
+      GeglBuffer *buffer = gimp_drawable_get_buffer (GIMP_DRAWABLE (mask));
+
+      gimp_gegl_mask_combine_buffer (buffer, add_on_buffer, op,
+                                     off_x, off_y);
+    }
+
+  gimp_channel_combine_end (mask, &data);
+}
diff --git a/app/core/gimpchannel-combine.h b/app/core/gimpchannel-combine.h
new file mode 100644
index 0000000..de1f125
--- /dev/null
+++ b/app/core/gimpchannel-combine.h
@@ -0,0 +1,56 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_CHANNEL_COMBINE_H__
+#define __GIMP_CHANNEL_COMBINE_H__
+
+
+void   gimp_channel_combine_rect         (GimpChannel    *mask,
+                                          GimpChannelOps  op,
+                                          gint            x,
+                                          gint            y,
+                                          gint            w,
+                                          gint            h);
+void   gimp_channel_combine_ellipse      (GimpChannel    *mask,
+                                          GimpChannelOps  op,
+                                          gint            x,
+                                          gint            y,
+                                          gint            w,
+                                          gint            h,
+                                          gboolean        antialias);
+void   gimp_channel_combine_ellipse_rect (GimpChannel    *mask,
+                                          GimpChannelOps  op,
+                                          gint            x,
+                                          gint            y,
+                                          gint            w,
+                                          gint            h,
+                                          gdouble         rx,
+                                          gdouble         ry,
+                                          gboolean        antialias);
+void   gimp_channel_combine_mask         (GimpChannel    *mask,
+                                          GimpChannel    *add_on,
+                                          GimpChannelOps  op,
+                                          gint            off_x,
+                                          gint            off_y);
+void   gimp_channel_combine_buffer       (GimpChannel    *mask,
+                                          GeglBuffer     *add_on_buffer,
+                                          GimpChannelOps  op,
+                                          gint            off_x,
+                                          gint            off_y);
+
+
+#endif /* __GIMP_CHANNEL_COMBINE_H__ */
diff --git a/app/core/gimpchannel-select.c b/app/core/gimpchannel-select.c
new file mode 100644
index 0000000..b76280e
--- /dev/null
+++ b/app/core/gimpchannel-select.c
@@ -0,0 +1,605 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <cairo.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpmath/gimpmath.h"
+
+#include "core-types.h"
+
+#include "gegl/gimp-gegl-apply-operation.h"
+#include "gegl/gimp-gegl-loops.h"
+#include "gegl/gimp-gegl-mask-combine.h"
+
+#include "gimpchannel.h"
+#include "gimpchannel-select.h"
+#include "gimpchannel-combine.h"
+#include "gimppickable.h"
+#include "gimppickable-contiguous-region.h"
+#include "gimpscanconvert.h"
+
+#include "vectors/gimpstroke.h"
+#include "vectors/gimpvectors.h"
+
+#include "gimp-intl.h"
+
+
+/*  basic selection functions  */
+
+void
+gimp_channel_select_rectangle (GimpChannel    *channel,
+                               gint            x,
+                               gint            y,
+                               gint            w,
+                               gint            h,
+                               GimpChannelOps  op,
+                               gboolean        feather,
+                               gdouble         feather_radius_x,
+                               gdouble         feather_radius_y,
+                               gboolean        push_undo)
+{
+  g_return_if_fail (GIMP_IS_CHANNEL (channel));
+  g_return_if_fail (gimp_item_is_attached (GIMP_ITEM (channel)));
+
+  if (push_undo)
+    gimp_channel_push_undo (channel, C_("undo-type", "Rectangle Select"));
+
+  /*  if feathering for rect, make a new mask with the
+   *  rectangle and feather that with the old mask
+   */
+  if (feather)
+    {
+      GimpItem   *item = GIMP_ITEM (channel);
+      GeglBuffer *add_on;
+
+      add_on = gegl_buffer_new (GEGL_RECTANGLE (0, 0,
+                                                gimp_item_get_width  (item),
+                                                gimp_item_get_height (item)),
+                                babl_format ("Y float"));
+
+      gimp_gegl_mask_combine_rect (add_on, GIMP_CHANNEL_OP_REPLACE, x, y, w, h);
+
+      gimp_gegl_apply_feather (add_on, NULL, NULL, add_on, NULL,
+                               feather_radius_x,
+                               feather_radius_y,
+                               TRUE);
+
+      gimp_channel_combine_buffer (channel, add_on, op, 0, 0);
+      g_object_unref (add_on);
+    }
+  else
+    {
+      gimp_channel_combine_rect (channel, op, x, y, w, h);
+    }
+}
+
+void
+gimp_channel_select_ellipse (GimpChannel    *channel,
+                             gint            x,
+                             gint            y,
+                             gint            w,
+                             gint            h,
+                             GimpChannelOps  op,
+                             gboolean        antialias,
+                             gboolean        feather,
+                             gdouble         feather_radius_x,
+                             gdouble         feather_radius_y,
+                             gboolean        push_undo)
+{
+  g_return_if_fail (GIMP_IS_CHANNEL (channel));
+  g_return_if_fail (gimp_item_is_attached (GIMP_ITEM (channel)));
+
+  if (push_undo)
+    gimp_channel_push_undo (channel, C_("undo-type", "Ellipse Select"));
+
+  /*  if feathering for rect, make a new mask with the
+   *  rectangle and feather that with the old mask
+   */
+  if (feather)
+    {
+      GimpItem   *item = GIMP_ITEM (channel);
+      GeglBuffer *add_on;
+
+      add_on = gegl_buffer_new (GEGL_RECTANGLE (0, 0,
+                                                gimp_item_get_width  (item),
+                                                gimp_item_get_height (item)),
+                                babl_format ("Y float"));
+
+      gimp_gegl_mask_combine_ellipse (add_on, GIMP_CHANNEL_OP_REPLACE,
+                                      x, y, w, h, antialias);
+
+      gimp_gegl_apply_feather (add_on, NULL, NULL, add_on, NULL,
+                               feather_radius_x,
+                               feather_radius_y,
+                               TRUE);
+
+      gimp_channel_combine_buffer (channel, add_on, op, 0, 0);
+      g_object_unref (add_on);
+    }
+  else
+    {
+      gimp_channel_combine_ellipse (channel, op, x, y, w, h, antialias);
+    }
+}
+
+void
+gimp_channel_select_round_rect (GimpChannel         *channel,
+                                gint                 x,
+                                gint                 y,
+                                gint                 w,
+                                gint                 h,
+                                gdouble              corner_radius_x,
+                                gdouble              corner_radius_y,
+                                GimpChannelOps       op,
+                                gboolean             antialias,
+                                gboolean             feather,
+                                gdouble              feather_radius_x,
+                                gdouble              feather_radius_y,
+                                gboolean             push_undo)
+{
+  g_return_if_fail (GIMP_IS_CHANNEL (channel));
+  g_return_if_fail (gimp_item_is_attached (GIMP_ITEM (channel)));
+
+  if (push_undo)
+    gimp_channel_push_undo (channel, C_("undo-type", "Rounded Rectangle Select"));
+
+  /*  if feathering for rect, make a new mask with the
+   *  rectangle and feather that with the old mask
+   */
+  if (feather)
+    {
+      GimpItem   *item = GIMP_ITEM (channel);
+      GeglBuffer *add_on;
+
+      add_on = gegl_buffer_new (GEGL_RECTANGLE (0, 0,
+                                                gimp_item_get_width  (item),
+                                                gimp_item_get_height (item)),
+                                babl_format ("Y float"));
+
+      gimp_gegl_mask_combine_ellipse_rect (add_on, GIMP_CHANNEL_OP_REPLACE,
+                                           x, y, w, h,
+                                           corner_radius_x, corner_radius_y,
+                                           antialias);
+
+      gimp_gegl_apply_feather (add_on, NULL, NULL, add_on, NULL,
+                               feather_radius_x,
+                               feather_radius_y,
+                               TRUE);
+
+      gimp_channel_combine_buffer (channel, add_on, op, 0, 0);
+      g_object_unref (add_on);
+    }
+  else
+    {
+      gimp_channel_combine_ellipse_rect (channel, op, x, y, w, h,
+                                         corner_radius_x, corner_radius_y,
+                                         antialias);
+    }
+}
+
+/*  select by GimpScanConvert functions  */
+
+void
+gimp_channel_select_scan_convert (GimpChannel     *channel,
+                                  const gchar     *undo_desc,
+                                  GimpScanConvert *scan_convert,
+                                  gint             offset_x,
+                                  gint             offset_y,
+                                  GimpChannelOps   op,
+                                  gboolean         antialias,
+                                  gboolean         feather,
+                                  gdouble          feather_radius_x,
+                                  gdouble          feather_radius_y,
+                                  gboolean         push_undo)
+{
+  GimpItem   *item;
+  GeglBuffer *add_on;
+
+  g_return_if_fail (GIMP_IS_CHANNEL (channel));
+  g_return_if_fail (gimp_item_is_attached (GIMP_ITEM (channel)));
+  g_return_if_fail (undo_desc != NULL);
+  g_return_if_fail (scan_convert != NULL);
+
+  if (push_undo)
+    gimp_channel_push_undo (channel, undo_desc);
+
+  item = GIMP_ITEM (channel);
+
+  add_on = gegl_buffer_new (GEGL_RECTANGLE (0, 0,
+                                            gimp_item_get_width  (item),
+                                            gimp_item_get_height (item)),
+                            babl_format ("Y float"));
+
+  gimp_scan_convert_render (scan_convert, add_on,
+                            offset_x, offset_y, antialias);
+
+  if (feather)
+    gimp_gegl_apply_feather (add_on, NULL, NULL, add_on, NULL,
+                             feather_radius_x,
+                             feather_radius_y,
+                             TRUE);
+
+  gimp_channel_combine_buffer (channel, add_on, op, 0, 0);
+  g_object_unref (add_on);
+}
+
+void
+gimp_channel_select_polygon (GimpChannel       *channel,
+                             const gchar       *undo_desc,
+                             gint               n_points,
+                             const GimpVector2 *points,
+                             GimpChannelOps     op,
+                             gboolean           antialias,
+                             gboolean           feather,
+                             gdouble            feather_radius_x,
+                             gdouble            feather_radius_y,
+                             gboolean           push_undo)
+{
+  GimpScanConvert *scan_convert;
+
+  g_return_if_fail (GIMP_IS_CHANNEL (channel));
+  g_return_if_fail (gimp_item_is_attached (GIMP_ITEM (channel)));
+  g_return_if_fail (undo_desc != NULL);
+
+  scan_convert = gimp_scan_convert_new ();
+
+  gimp_scan_convert_add_polyline (scan_convert, n_points, points, TRUE);
+
+  gimp_channel_select_scan_convert (channel, undo_desc, scan_convert, 0, 0,
+                                    op, antialias, feather,
+                                    feather_radius_x, feather_radius_y,
+                                    push_undo);
+
+  gimp_scan_convert_free (scan_convert);
+}
+
+void
+gimp_channel_select_vectors (GimpChannel    *channel,
+                             const gchar    *undo_desc,
+                             GimpVectors    *vectors,
+                             GimpChannelOps  op,
+                             gboolean        antialias,
+                             gboolean        feather,
+                             gdouble         feather_radius_x,
+                             gdouble         feather_radius_y,
+                             gboolean        push_undo)
+{
+  const GimpBezierDesc *bezier;
+
+  g_return_if_fail (GIMP_IS_CHANNEL (channel));
+  g_return_if_fail (gimp_item_is_attached (GIMP_ITEM (channel)));
+  g_return_if_fail (undo_desc != NULL);
+  g_return_if_fail (GIMP_IS_VECTORS (vectors));
+
+  bezier = gimp_vectors_get_bezier (vectors);
+
+  if (bezier && bezier->num_data > 4)
+    {
+      GimpScanConvert *scan_convert;
+
+      scan_convert = gimp_scan_convert_new ();
+      gimp_scan_convert_add_bezier (scan_convert, bezier);
+
+      gimp_channel_select_scan_convert (channel, undo_desc, scan_convert, 0, 0,
+                                        op, antialias, feather,
+                                        feather_radius_x, feather_radius_y,
+                                        push_undo);
+
+      gimp_scan_convert_free (scan_convert);
+    }
+}
+
+
+/*  select by GimpChannel functions  */
+
+void
+gimp_channel_select_buffer (GimpChannel    *channel,
+                            const gchar    *undo_desc,
+                            GeglBuffer     *add_on,
+                            gint            offset_x,
+                            gint            offset_y,
+                            GimpChannelOps  op,
+                            gboolean        feather,
+                            gdouble         feather_radius_x,
+                            gdouble         feather_radius_y)
+{
+  g_return_if_fail (GIMP_IS_CHANNEL (channel));
+  g_return_if_fail (gimp_item_is_attached (GIMP_ITEM (channel)));
+  g_return_if_fail (undo_desc != NULL);
+  g_return_if_fail (GEGL_IS_BUFFER (add_on));
+
+  gimp_channel_push_undo (channel, undo_desc);
+
+  if (feather)
+    {
+      GimpItem   *item = GIMP_ITEM (channel);
+      GeglBuffer *add_on2;
+
+      add_on2 = gegl_buffer_new (GEGL_RECTANGLE (0, 0,
+                                                 gimp_item_get_width  (item),
+                                                 gimp_item_get_height (item)),
+                                 babl_format ("Y float"));
+
+      gimp_gegl_mask_combine_buffer (add_on2, add_on,
+                                     GIMP_CHANNEL_OP_REPLACE,
+                                     offset_x, offset_y);
+
+      gimp_gegl_apply_feather (add_on2, NULL, NULL, add_on2, NULL,
+                               feather_radius_x,
+                               feather_radius_y,
+                               TRUE);
+
+      gimp_channel_combine_buffer (channel, add_on2, op, 0, 0);
+      g_object_unref (add_on2);
+    }
+  else
+    {
+      gimp_channel_combine_buffer (channel, add_on, op, offset_x, offset_y);
+    }
+}
+
+void
+gimp_channel_select_channel (GimpChannel    *channel,
+                             const gchar    *undo_desc,
+                             GimpChannel    *add_on,
+                             gint            offset_x,
+                             gint            offset_y,
+                             GimpChannelOps  op,
+                             gboolean        feather,
+                             gdouble         feather_radius_x,
+                             gdouble         feather_radius_y)
+{
+  g_return_if_fail (GIMP_IS_CHANNEL (channel));
+  g_return_if_fail (gimp_item_is_attached (GIMP_ITEM (channel)));
+  g_return_if_fail (undo_desc != NULL);
+  g_return_if_fail (GIMP_IS_CHANNEL (add_on));
+
+  gimp_channel_select_buffer (channel, undo_desc,
+                              gimp_drawable_get_buffer (GIMP_DRAWABLE (add_on)),
+                              offset_x, offset_y, op,
+                              feather,
+                              feather_radius_x, feather_radius_y);
+}
+
+void
+gimp_channel_select_alpha (GimpChannel    *channel,
+                           GimpDrawable   *drawable,
+                           GimpChannelOps  op,
+                           gboolean        feather,
+                           gdouble         feather_radius_x,
+                           gdouble         feather_radius_y)
+{
+  GimpItem    *item;
+  GimpChannel *add_on;
+  gint         off_x, off_y;
+
+  g_return_if_fail (GIMP_IS_CHANNEL (channel));
+  g_return_if_fail (gimp_item_is_attached (GIMP_ITEM (channel)));
+  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
+
+  item = GIMP_ITEM (channel);
+
+  if (gimp_drawable_has_alpha (drawable))
+    {
+      add_on = gimp_channel_new_from_alpha (gimp_item_get_image (item),
+                                            drawable, NULL, NULL);
+    }
+  else
+    {
+      /*  no alpha is equivalent to completely opaque alpha,
+       *  so simply select the whole layer's extents.  --mitch
+       */
+      add_on = gimp_channel_new_mask (gimp_item_get_image (item),
+                                      gimp_item_get_width  (GIMP_ITEM (drawable)),
+                                      gimp_item_get_height (GIMP_ITEM (drawable)));
+      gimp_channel_all (add_on, FALSE);
+    }
+
+  gimp_item_get_offset (GIMP_ITEM (drawable), &off_x, &off_y);
+
+  gimp_channel_select_channel (channel, C_("undo-type", "Alpha to Selection"), add_on,
+                               off_x, off_y,
+                               op, feather,
+                               feather_radius_x,
+                               feather_radius_y);
+  g_object_unref (add_on);
+}
+
+void
+gimp_channel_select_component (GimpChannel     *channel,
+                               GimpChannelType  component,
+                               GimpChannelOps   op,
+                               gboolean         feather,
+                               gdouble          feather_radius_x,
+                               gdouble          feather_radius_y)
+{
+  GimpItem    *item;
+  GimpChannel *add_on;
+  const gchar *desc;
+  gchar       *undo_desc;
+
+  g_return_if_fail (GIMP_IS_CHANNEL (channel));
+  g_return_if_fail (gimp_item_is_attached (GIMP_ITEM (channel)));
+
+  item = GIMP_ITEM (channel);
+
+  add_on = gimp_channel_new_from_component (gimp_item_get_image (item),
+                                            component, NULL, NULL);
+
+  if (feather)
+    gimp_channel_feather (add_on,
+                          feather_radius_x,
+                          feather_radius_y,
+                          TRUE,
+                          FALSE /* no undo */);
+
+  gimp_enum_get_value (GIMP_TYPE_CHANNEL_TYPE, component,
+                       NULL, NULL, &desc, NULL);
+
+  undo_desc = g_strdup_printf (C_("undo-type", "%s Channel to Selection"), desc);
+
+  gimp_channel_select_channel (channel, undo_desc, add_on,
+                               0, 0, op,
+                               FALSE, 0.0, 0.0);
+
+  g_free (undo_desc);
+  g_object_unref (add_on);
+}
+
+void
+gimp_channel_select_fuzzy (GimpChannel         *channel,
+                           GimpDrawable        *drawable,
+                           gboolean             sample_merged,
+                           gint                 x,
+                           gint                 y,
+                           gfloat               threshold,
+                           gboolean             select_transparent,
+                           GimpSelectCriterion  select_criterion,
+                           gboolean             diagonal_neighbors,
+                           GimpChannelOps       op,
+                           gboolean             antialias,
+                           gboolean             feather,
+                           gdouble              feather_radius_x,
+                           gdouble              feather_radius_y)
+{
+  GimpPickable *pickable;
+  GeglBuffer   *add_on;
+  gint          add_on_x = 0;
+  gint          add_on_y = 0;
+
+  g_return_if_fail (GIMP_IS_CHANNEL (channel));
+  g_return_if_fail (gimp_item_is_attached (GIMP_ITEM (channel)));
+  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
+
+  if (sample_merged)
+    pickable = GIMP_PICKABLE (gimp_item_get_image (GIMP_ITEM (drawable)));
+  else
+    pickable = GIMP_PICKABLE (drawable);
+
+  add_on = gimp_pickable_contiguous_region_by_seed (pickable,
+                                                    antialias,
+                                                    threshold,
+                                                    select_transparent,
+                                                    select_criterion,
+                                                    diagonal_neighbors,
+                                                    x, y);
+
+  if (! sample_merged)
+    gimp_item_get_offset (GIMP_ITEM (drawable), &add_on_x, &add_on_y);
+
+  gimp_channel_select_buffer (channel, C_("undo-type", "Fuzzy Select"),
+                              add_on, add_on_x, add_on_y,
+                              op,
+                              feather,
+                              feather_radius_x,
+                              feather_radius_y);
+  g_object_unref (add_on);
+}
+
+void
+gimp_channel_select_by_color (GimpChannel         *channel,
+                              GimpDrawable        *drawable,
+                              gboolean             sample_merged,
+                              const GimpRGB       *color,
+                              gfloat               threshold,
+                              gboolean             select_transparent,
+                              GimpSelectCriterion  select_criterion,
+                              GimpChannelOps       op,
+                              gboolean             antialias,
+                              gboolean             feather,
+                              gdouble              feather_radius_x,
+                              gdouble              feather_radius_y)
+{
+  GimpPickable *pickable;
+  GeglBuffer   *add_on;
+  gint          add_on_x = 0;
+  gint          add_on_y = 0;
+
+  g_return_if_fail (GIMP_IS_CHANNEL (channel));
+  g_return_if_fail (gimp_item_is_attached (GIMP_ITEM (channel)));
+  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
+  g_return_if_fail (color != NULL);
+
+  if (sample_merged)
+    pickable = GIMP_PICKABLE (gimp_item_get_image (GIMP_ITEM (drawable)));
+  else
+    pickable = GIMP_PICKABLE (drawable);
+
+  add_on = gimp_pickable_contiguous_region_by_color (pickable,
+                                                     antialias,
+                                                     threshold,
+                                                     select_transparent,
+                                                     select_criterion,
+                                                     color);
+
+  if (! sample_merged)
+    gimp_item_get_offset (GIMP_ITEM (drawable), &add_on_x, &add_on_y);
+
+  gimp_channel_select_buffer (channel, C_("undo-type", "Select by Color"),
+                              add_on, add_on_x, add_on_y,
+                              op,
+                              feather,
+                              feather_radius_x,
+                              feather_radius_y);
+  g_object_unref (add_on);
+}
+
+void
+gimp_channel_select_by_index (GimpChannel    *channel,
+                              GimpDrawable   *drawable,
+                              gint            index,
+                              GimpChannelOps  op,
+                              gboolean        feather,
+                              gdouble         feather_radius_x,
+                              gdouble         feather_radius_y)
+{
+  GeglBuffer *add_on;
+  gint        add_on_x = 0;
+  gint        add_on_y = 0;
+
+  g_return_if_fail (GIMP_IS_CHANNEL (channel));
+  g_return_if_fail (gimp_item_is_attached (GIMP_ITEM (channel)));
+  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
+  g_return_if_fail (gimp_drawable_is_indexed (drawable));
+
+  add_on = gegl_buffer_new (GEGL_RECTANGLE (0, 0,
+                                            gimp_item_get_width  (GIMP_ITEM (drawable)),
+                                            gimp_item_get_height (GIMP_ITEM (drawable))),
+                            babl_format ("Y float"));
+
+  gimp_gegl_index_to_mask (gimp_drawable_get_buffer (drawable), NULL,
+                           gimp_drawable_get_format_without_alpha (drawable),
+                           add_on, NULL,
+                           index);
+
+  gimp_item_get_offset (GIMP_ITEM (drawable), &add_on_x, &add_on_y);
+
+  gimp_channel_select_buffer (channel, C_("undo-type", "Select by Indexed Color"),
+                              add_on, add_on_x, add_on_y,
+                              op,
+                              feather,
+                              feather_radius_x,
+                              feather_radius_y);
+  g_object_unref (add_on);
+}
diff --git a/app/core/gimpchannel-select.h b/app/core/gimpchannel-select.h
new file mode 100644
index 0000000..ca2680d
--- /dev/null
+++ b/app/core/gimpchannel-select.h
@@ -0,0 +1,160 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_CHANNEL_SELECT_H__
+#define __GIMP_CHANNEL_SELECT_H__
+
+
+/*  basic selection functions  */
+
+void   gimp_channel_select_rectangle    (GimpChannel         *channel,
+                                         gint                 x,
+                                         gint                 y,
+                                         gint                 w,
+                                         gint                 h,
+                                         GimpChannelOps       op,
+                                         gboolean             feather,
+                                         gdouble              feather_radius_x,
+                                         gdouble              feather_radius_y,
+                                         gboolean             push_undo);
+void   gimp_channel_select_ellipse      (GimpChannel         *channel,
+                                         gint                 x,
+                                         gint                 y,
+                                         gint                 w,
+                                         gint                 h,
+                                         GimpChannelOps       op,
+                                         gboolean             antialias,
+                                         gboolean             feather,
+                                         gdouble              feather_radius_x,
+                                         gdouble              feather_radius_y,
+                                         gboolean             push_undo);
+void   gimp_channel_select_round_rect   (GimpChannel         *channel,
+                                         gint                 x,
+                                         gint                 y,
+                                         gint                 w,
+                                         gint                 h,
+                                         gdouble              corner_radius_y,
+                                         gdouble              corner_radius_x,
+                                         GimpChannelOps       op,
+                                         gboolean             antialias,
+                                         gboolean             feather,
+                                         gdouble              feather_radius_x,
+                                         gdouble              feather_radius_y,
+                                         gboolean             push_undo);
+
+/*  select by GimpScanConvert functions  */
+
+void   gimp_channel_select_scan_convert (GimpChannel         *channel,
+                                         const gchar         *undo_desc,
+                                         GimpScanConvert     *scan_convert,
+                                         gint                 offset_x,
+                                         gint                 offset_y,
+                                         GimpChannelOps       op,
+                                         gboolean             antialias,
+                                         gboolean             feather,
+                                         gdouble              feather_radius_x,
+                                         gdouble              feather_radius_y,
+                                         gboolean             push_undo);
+void   gimp_channel_select_polygon      (GimpChannel         *channel,
+                                         const gchar         *undo_desc,
+                                         gint                 n_points,
+                                         const GimpVector2   *points,
+                                         GimpChannelOps       op,
+                                         gboolean             antialias,
+                                         gboolean             feather,
+                                         gdouble              feather_radius_x,
+                                         gdouble              feather_radius_y,
+                                         gboolean             push_undo);
+void   gimp_channel_select_vectors      (GimpChannel         *channel,
+                                         const gchar         *undo_desc,
+                                         GimpVectors         *vectors,
+                                         GimpChannelOps       op,
+                                         gboolean             antialias,
+                                         gboolean             feather,
+                                         gdouble              feather_radius_x,
+                                         gdouble              feather_radius_y,
+                                         gboolean             push_undo);
+void   gimp_channel_select_buffer       (GimpChannel         *channel,
+                                         const gchar         *undo_desc,
+                                         GeglBuffer          *add_on,
+                                         gint                 offset_x,
+                                         gint                 offset_y,
+                                         GimpChannelOps       op,
+                                         gboolean             feather,
+                                         gdouble              feather_radius_x,
+                                         gdouble              feather_radius_y);
+
+
+/*  select by GimpChannel functions  */
+
+void   gimp_channel_select_channel      (GimpChannel         *channel,
+                                         const gchar         *undo_desc,
+                                         GimpChannel         *add_on,
+                                         gint                 offset_x,
+                                         gint                 offset_y,
+                                         GimpChannelOps       op,
+                                         gboolean             feather,
+                                         gdouble              feather_radius_x,
+                                         gdouble              feather_radius_y);
+void   gimp_channel_select_alpha        (GimpChannel         *channel,
+                                         GimpDrawable        *drawable,
+                                         GimpChannelOps       op,
+                                         gboolean             feather,
+                                         gdouble              feather_radius_x,
+                                         gdouble              feather_radius_y);
+void   gimp_channel_select_component    (GimpChannel         *channel,
+                                         GimpChannelType      component,
+                                         GimpChannelOps       op,
+                                         gboolean             feather,
+                                         gdouble              feather_radius_x,
+                                         gdouble              feather_radius_y);
+void   gimp_channel_select_fuzzy        (GimpChannel         *channel,
+                                         GimpDrawable        *drawable,
+                                         gboolean             sample_merged,
+                                         gint                 x,
+                                         gint                 y,
+                                         gfloat               threshold,
+                                         gboolean             select_transparent,
+                                         GimpSelectCriterion  select_criterion,
+                                         gboolean             diagonal_neighbors,
+                                         GimpChannelOps       op,
+                                         gboolean             antialias,
+                                         gboolean             feather,
+                                         gdouble              feather_radius_x,
+                                         gdouble              feather_radius_y);
+void   gimp_channel_select_by_color     (GimpChannel         *channel,
+                                         GimpDrawable        *drawable,
+                                         gboolean             sample_merged,
+                                         const GimpRGB       *color,
+                                         gfloat               threshold,
+                                         gboolean             select_transparent,
+                                         GimpSelectCriterion  select_criterion,
+                                         GimpChannelOps       op,
+                                         gboolean             antialias,
+                                         gboolean             feather,
+                                         gdouble              feather_radius_x,
+                                         gdouble              feather_radius_y);
+void   gimp_channel_select_by_index     (GimpChannel         *channel,
+                                         GimpDrawable        *drawable,
+                                         gint                 index,
+                                         GimpChannelOps       op,
+                                         gboolean             feather,
+                                         gdouble              feather_radius_x,
+                                         gdouble              feather_radius_y);
+
+
+#endif  /*  __GIMP_CHANNEL_SELECT_H__  */
diff --git a/app/core/gimpchannel.c b/app/core/gimpchannel.c
new file mode 100644
index 0000000..784551a
--- /dev/null
+++ b/app/core/gimpchannel.c
@@ -0,0 +1,1956 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <cairo.h>
+#include <gegl.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpmath/gimpmath.h"
+#include "libgimpcolor/gimpcolor.h"
+
+#include "core-types.h"
+
+#include "paint/gimppaintcore-stroke.h"
+#include "paint/gimppaintoptions.h"
+
+#include "gegl/gimp-gegl-apply-operation.h"
+#include "gegl/gimp-gegl-loops.h"
+#include "gegl/gimp-gegl-mask.h"
+#include "gegl/gimp-gegl-nodes.h"
+
+#include "gimp.h"
+#include "gimp-utils.h"
+#include "gimpboundary.h"
+#include "gimpcontainer.h"
+#include "gimperror.h"
+#include "gimpimage.h"
+#include "gimpimage-quick-mask.h"
+#include "gimpimage-undo.h"
+#include "gimpimage-undo-push.h"
+#include "gimpchannel.h"
+#include "gimpchannel-select.h"
+#include "gimpcontext.h"
+#include "gimpdrawable-fill.h"
+#include "gimpdrawable-stroke.h"
+#include "gimpmarshal.h"
+#include "gimppaintinfo.h"
+#include "gimppickable.h"
+#include "gimpstrokeoptions.h"
+
+#include "gimp-intl.h"
+
+
+#define RGBA_EPSILON 1e-6
+
+enum
+{
+  COLOR_CHANGED,
+  LAST_SIGNAL
+};
+
+
+static void gimp_channel_pickable_iface_init (GimpPickableInterface *iface);
+
+static void       gimp_channel_finalize      (GObject           *object);
+
+static gint64     gimp_channel_get_memsize   (GimpObject        *object,
+                                              gint64            *gui_size);
+
+static gchar  * gimp_channel_get_description (GimpViewable      *viewable,
+                                              gchar            **tooltip);
+
+static GeglNode * gimp_channel_get_node      (GimpFilter        *filter);
+
+static gboolean   gimp_channel_is_attached   (GimpItem          *item);
+static GimpItemTree * gimp_channel_get_tree  (GimpItem          *item);
+static gboolean   gimp_channel_bounds        (GimpItem          *item,
+                                              gdouble           *x,
+                                              gdouble           *y,
+                                              gdouble           *width,
+                                              gdouble           *height);
+static GimpItem * gimp_channel_duplicate     (GimpItem          *item,
+                                              GType              new_type);
+static void       gimp_channel_convert       (GimpItem          *item,
+                                              GimpImage         *dest_image,
+                                              GType              old_type);
+static void       gimp_channel_translate     (GimpItem          *item,
+                                              gdouble            off_x,
+                                              gdouble            off_y,
+                                              gboolean           push_undo);
+static void       gimp_channel_scale         (GimpItem          *item,
+                                              gint               new_width,
+                                              gint               new_height,
+                                              gint               new_offset_x,
+                                              gint               new_offset_y,
+                                              GimpInterpolationType interp_type,
+                                              GimpProgress      *progress);
+static void       gimp_channel_resize        (GimpItem          *item,
+                                              GimpContext       *context,
+                                              GimpFillType       fill_type,
+                                              gint               new_width,
+                                              gint               new_height,
+                                              gint               offset_x,
+                                              gint               offset_y);
+static GimpTransformResize
+                  gimp_channel_get_clip      (GimpItem          *item,
+                                              GimpTransformResize clip_result);
+static gboolean   gimp_channel_fill          (GimpItem          *item,
+                                              GimpDrawable      *drawable,
+                                              GimpFillOptions   *fill_options,
+                                              gboolean           push_undo,
+                                              GimpProgress      *progress,
+                                              GError           **error);
+static gboolean   gimp_channel_stroke        (GimpItem          *item,
+                                              GimpDrawable      *drawable,
+                                              GimpStrokeOptions *stroke_options,
+                                              gboolean           push_undo,
+                                              GimpProgress      *progress,
+                                              GError           **error);
+static void       gimp_channel_to_selection  (GimpItem          *item,
+                                              GimpChannelOps     op,
+                                              gboolean           antialias,
+                                              gboolean           feather,
+                                              gdouble            feather_radius_x,
+                                              gdouble            feather_radius_y);
+
+static void       gimp_channel_convert_type  (GimpDrawable      *drawable,
+                                              GimpImage         *dest_image,
+                                              const Babl        *new_format,
+                                              GimpColorProfile  *dest_profile,
+                                              GeglDitherMethod   layer_dither_type,
+                                              GeglDitherMethod   mask_dither_type,
+                                              gboolean           push_undo,
+                                              GimpProgress      *progress);
+static void gimp_channel_invalidate_boundary   (GimpDrawable       *drawable);
+static void gimp_channel_get_active_components (GimpDrawable       *drawable,
+                                                gboolean           *active);
+
+static void      gimp_channel_set_buffer     (GimpDrawable        *drawable,
+                                              gboolean             push_undo,
+                                              const gchar         *undo_desc,
+                                              GeglBuffer          *buffer,
+                                              const GeglRectangle *bounds);
+
+static gdouble   gimp_channel_get_opacity_at (GimpPickable        *pickable,
+                                              gint                 x,
+                                              gint                 y);
+
+static gboolean   gimp_channel_real_boundary (GimpChannel         *channel,
+                                              const GimpBoundSeg **segs_in,
+                                              const GimpBoundSeg **segs_out,
+                                              gint                *num_segs_in,
+                                              gint                *num_segs_out,
+                                              gint                 x1,
+                                              gint                 y1,
+                                              gint                 x2,
+                                              gint                 y2);
+static gboolean   gimp_channel_real_is_empty (GimpChannel         *channel);
+static void       gimp_channel_real_feather  (GimpChannel         *channel,
+                                              gdouble              radius_x,
+                                              gdouble              radius_y,
+                                              gboolean             edge_lock,
+                                              gboolean             push_undo);
+static void       gimp_channel_real_sharpen  (GimpChannel         *channel,
+                                              gboolean             push_undo);
+static void       gimp_channel_real_clear    (GimpChannel         *channel,
+                                              const gchar         *undo_desc,
+                                              gboolean             push_undo);
+static void       gimp_channel_real_all      (GimpChannel         *channel,
+                                              gboolean             push_undo);
+static void       gimp_channel_real_invert   (GimpChannel         *channel,
+                                              gboolean             push_undo);
+static void       gimp_channel_real_border   (GimpChannel         *channel,
+                                              gint                 radius_x,
+                                              gint                 radius_y,
+                                              GimpChannelBorderStyle style,
+                                              gboolean             edge_lock,
+                                              gboolean             push_undo);
+static void       gimp_channel_real_grow     (GimpChannel         *channel,
+                                              gint                 radius_x,
+                                              gint                 radius_y,
+                                              gboolean             push_undo);
+static void       gimp_channel_real_shrink   (GimpChannel         *channel,
+                                              gint                 radius_x,
+                                              gint                 radius_y,
+                                              gboolean             edge_lock,
+                                              gboolean             push_undo);
+static void       gimp_channel_real_flood    (GimpChannel         *channel,
+                                              gboolean             push_undo);
+
+
+static void      gimp_channel_buffer_changed (GeglBuffer          *buffer,
+                                              const GeglRectangle *rect,
+                                              GimpChannel         *channel);
+
+
+G_DEFINE_TYPE_WITH_CODE (GimpChannel, gimp_channel, GIMP_TYPE_DRAWABLE,
+                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_PICKABLE,
+                                                gimp_channel_pickable_iface_init))
+
+#define parent_class gimp_channel_parent_class
+
+static guint channel_signals[LAST_SIGNAL] = { 0 };
+
+
+static void
+gimp_channel_class_init (GimpChannelClass *klass)
+{
+  GObjectClass      *object_class      = G_OBJECT_CLASS (klass);
+  GimpObjectClass   *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+  GimpViewableClass *viewable_class    = GIMP_VIEWABLE_CLASS (klass);
+  GimpFilterClass   *filter_class      = GIMP_FILTER_CLASS (klass);
+  GimpItemClass     *item_class        = GIMP_ITEM_CLASS (klass);
+  GimpDrawableClass *drawable_class    = GIMP_DRAWABLE_CLASS (klass);
+
+  channel_signals[COLOR_CHANGED] =
+    g_signal_new ("color-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpChannelClass, color_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  object_class->finalize            = gimp_channel_finalize;
+
+  gimp_object_class->get_memsize    = gimp_channel_get_memsize;
+
+  viewable_class->get_description   = gimp_channel_get_description;
+  viewable_class->default_icon_name = "gimp-channel";
+
+  filter_class->get_node            = gimp_channel_get_node;
+
+  item_class->is_attached          = gimp_channel_is_attached;
+  item_class->get_tree             = gimp_channel_get_tree;
+  item_class->bounds               = gimp_channel_bounds;
+  item_class->duplicate            = gimp_channel_duplicate;
+  item_class->convert              = gimp_channel_convert;
+  item_class->translate            = gimp_channel_translate;
+  item_class->scale                = gimp_channel_scale;
+  item_class->resize               = gimp_channel_resize;
+  item_class->get_clip             = gimp_channel_get_clip;
+  item_class->fill                 = gimp_channel_fill;
+  item_class->stroke               = gimp_channel_stroke;
+  item_class->to_selection         = gimp_channel_to_selection;
+  item_class->default_name         = _("Channel");
+  item_class->rename_desc          = C_("undo-type", "Rename Channel");
+  item_class->translate_desc       = C_("undo-type", "Move Channel");
+  item_class->scale_desc           = C_("undo-type", "Scale Channel");
+  item_class->resize_desc          = C_("undo-type", "Resize Channel");
+  item_class->flip_desc            = C_("undo-type", "Flip Channel");
+  item_class->rotate_desc          = C_("undo-type", "Rotate Channel");
+  item_class->transform_desc       = C_("undo-type", "Transform Channel");
+  item_class->fill_desc            = C_("undo-type", "Fill Channel");
+  item_class->stroke_desc          = C_("undo-type", "Stroke Channel");
+  item_class->to_selection_desc    = C_("undo-type", "Channel to Selection");
+  item_class->reorder_desc         = C_("undo-type", "Reorder Channel");
+  item_class->raise_desc           = C_("undo-type", "Raise Channel");
+  item_class->raise_to_top_desc    = C_("undo-type", "Raise Channel to Top");
+  item_class->lower_desc           = C_("undo-type", "Lower Channel");
+  item_class->lower_to_bottom_desc = C_("undo-type", "Lower Channel to Bottom");
+  item_class->raise_failed         = _("Channel cannot be raised higher.");
+  item_class->lower_failed         = _("Channel cannot be lowered more.");
+
+  drawable_class->convert_type          = gimp_channel_convert_type;
+  drawable_class->invalidate_boundary   = gimp_channel_invalidate_boundary;
+  drawable_class->get_active_components = gimp_channel_get_active_components;
+  drawable_class->set_buffer            = gimp_channel_set_buffer;
+
+  klass->boundary       = gimp_channel_real_boundary;
+  klass->is_empty       = gimp_channel_real_is_empty;
+  klass->feather        = gimp_channel_real_feather;
+  klass->sharpen        = gimp_channel_real_sharpen;
+  klass->clear          = gimp_channel_real_clear;
+  klass->all            = gimp_channel_real_all;
+  klass->invert         = gimp_channel_real_invert;
+  klass->border         = gimp_channel_real_border;
+  klass->grow           = gimp_channel_real_grow;
+  klass->shrink         = gimp_channel_real_shrink;
+  klass->flood          = gimp_channel_real_flood;
+
+  klass->feather_desc   = C_("undo-type", "Feather Channel");
+  klass->sharpen_desc   = C_("undo-type", "Sharpen Channel");
+  klass->clear_desc     = C_("undo-type", "Clear Channel");
+  klass->all_desc       = C_("undo-type", "Fill Channel");
+  klass->invert_desc    = C_("undo-type", "Invert Channel");
+  klass->border_desc    = C_("undo-type", "Border Channel");
+  klass->grow_desc      = C_("undo-type", "Grow Channel");
+  klass->shrink_desc    = C_("undo-type", "Shrink Channel");
+  klass->flood_desc     = C_("undo-type", "Flood Channel");
+}
+
+static void
+gimp_channel_init (GimpChannel *channel)
+{
+  gimp_rgba_set (&channel->color, 0.0, 0.0, 0.0, GIMP_OPACITY_OPAQUE);
+
+  channel->show_masked    = FALSE;
+
+  /*  Selection mask variables  */
+  channel->boundary_known = FALSE;
+  channel->segs_in        = NULL;
+  channel->segs_out       = NULL;
+  channel->num_segs_in    = 0;
+  channel->num_segs_out   = 0;
+  channel->empty          = FALSE;
+  channel->bounds_known   = FALSE;
+  channel->x1             = 0;
+  channel->y1             = 0;
+  channel->x2             = 0;
+  channel->y2             = 0;
+}
+
+static void
+gimp_channel_pickable_iface_init (GimpPickableInterface *iface)
+{
+  iface->get_opacity_at = gimp_channel_get_opacity_at;
+}
+
+static void
+gimp_channel_finalize (GObject *object)
+{
+  GimpChannel *channel = GIMP_CHANNEL (object);
+
+  g_clear_pointer (&channel->segs_in,  g_free);
+  g_clear_pointer (&channel->segs_out, g_free);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static gint64
+gimp_channel_get_memsize (GimpObject *object,
+                          gint64     *gui_size)
+{
+  GimpChannel *channel = GIMP_CHANNEL (object);
+
+  *gui_size += channel->num_segs_in  * sizeof (GimpBoundSeg);
+  *gui_size += channel->num_segs_out * sizeof (GimpBoundSeg);
+
+  return GIMP_OBJECT_CLASS (parent_class)->get_memsize (object, gui_size);
+}
+
+static gchar *
+gimp_channel_get_description (GimpViewable  *viewable,
+                              gchar        **tooltip)
+{
+  if (! strcmp (GIMP_IMAGE_QUICK_MASK_NAME,
+                gimp_object_get_name (viewable)))
+    {
+      return g_strdup (_("Quick Mask"));
+    }
+
+  return GIMP_VIEWABLE_CLASS (parent_class)->get_description (viewable,
+                                                              tooltip);
+}
+
+static GeglNode *
+gimp_channel_get_node (GimpFilter *filter)
+{
+  GimpDrawable *drawable = GIMP_DRAWABLE (filter);
+  GimpChannel  *channel  = GIMP_CHANNEL (filter);
+  GeglNode     *node;
+  GeglNode     *source;
+  GeglNode     *mode_node;
+  const Babl   *color_format;
+
+  node = GIMP_FILTER_CLASS (parent_class)->get_node (filter);
+
+  source = gimp_drawable_get_source_node (drawable);
+  gegl_node_add_child (node, source);
+
+  g_warn_if_fail (channel->color_node == NULL);
+
+  if (gimp_drawable_get_linear (drawable))
+    color_format = babl_format ("RGBA float");
+  else
+    color_format = babl_format ("R'G'B'A float");
+
+  channel->color_node = gegl_node_new_child (node,
+                                             "operation", "gegl:color",
+                                             "format",    color_format,
+                                             NULL);
+  gimp_gegl_node_set_color (channel->color_node,
+                            &channel->color);
+
+  g_warn_if_fail (channel->mask_node == NULL);
+
+  channel->mask_node = gegl_node_new_child (node,
+                                            "operation", "gegl:opacity",
+                                            NULL);
+  gegl_node_connect_to (channel->color_node, "output",
+                        channel->mask_node,  "input");
+
+  g_warn_if_fail (channel->invert_node == NULL);
+
+  channel->invert_node = gegl_node_new_child (node,
+                                              "operation", "gegl:invert-linear",
+                                              NULL);
+
+  if (channel->show_masked)
+    {
+      gegl_node_connect_to (source,               "output",
+                            channel->invert_node, "input");
+      gegl_node_connect_to (channel->invert_node, "output",
+                            channel->mask_node,   "aux");
+    }
+  else
+    {
+      gegl_node_connect_to (source,             "output",
+                            channel->mask_node, "aux");
+    }
+
+  mode_node = gimp_drawable_get_mode_node (drawable);
+
+  gegl_node_connect_to (channel->mask_node, "output",
+                        mode_node,          "aux");
+
+  return node;
+}
+
+static gboolean
+gimp_channel_is_attached (GimpItem *item)
+{
+  GimpImage *image = gimp_item_get_image (item);
+
+  return (GIMP_IS_IMAGE (image) &&
+          gimp_container_have (gimp_image_get_channels (image),
+                               GIMP_OBJECT (item)));
+}
+
+static GimpItemTree *
+gimp_channel_get_tree (GimpItem *item)
+{
+  if (gimp_item_is_attached (item))
+    {
+      GimpImage *image = gimp_item_get_image (item);
+
+      return gimp_image_get_channel_tree (image);
+    }
+
+  return NULL;
+}
+
+static gboolean
+gimp_channel_bounds (GimpItem *item,
+                     gdouble  *x,
+                     gdouble  *y,
+                     gdouble  *width,
+                     gdouble  *height)
+{
+  GimpChannel *channel = GIMP_CHANNEL (item);
+
+  if (! channel->bounds_known)
+    {
+      GeglBuffer *buffer = gimp_drawable_get_buffer (GIMP_DRAWABLE (channel));
+
+      channel->empty = ! gimp_gegl_mask_bounds (buffer,
+                                                &channel->x1,
+                                                &channel->y1,
+                                                &channel->x2,
+                                                &channel->y2);
+
+      channel->bounds_known = TRUE;
+    }
+
+  *x      = channel->x1;
+  *y      = channel->y1;
+  *width  = channel->x2 - channel->x1;
+  *height = channel->y2 - channel->y1;
+
+  return ! channel->empty;
+}
+
+static GimpItem *
+gimp_channel_duplicate (GimpItem *item,
+                        GType     new_type)
+{
+  GimpItem *new_item;
+
+  g_return_val_if_fail (g_type_is_a (new_type, GIMP_TYPE_DRAWABLE), NULL);
+
+  new_item = GIMP_ITEM_CLASS (parent_class)->duplicate (item, new_type);
+
+  if (GIMP_IS_CHANNEL (new_item))
+    {
+      GimpChannel *channel     = GIMP_CHANNEL (item);
+      GimpChannel *new_channel = GIMP_CHANNEL (new_item);
+
+      new_channel->color        = channel->color;
+      new_channel->show_masked  = channel->show_masked;
+
+      /*  selection mask variables  */
+      new_channel->bounds_known = channel->bounds_known;
+      new_channel->empty        = channel->empty;
+      new_channel->x1           = channel->x1;
+      new_channel->y1           = channel->y1;
+      new_channel->x2           = channel->x2;
+      new_channel->y2           = channel->y2;
+
+      if (new_type == GIMP_TYPE_CHANNEL)
+        {
+          /*  8-bit channel hack: make sure pixels between all sorts
+           *  of channels of an image is always copied without any
+           *  gamma conversion
+           */
+          GimpDrawable *new_drawable = GIMP_DRAWABLE (new_item);
+          GimpImage    *image        = gimp_item_get_image (item);
+          const Babl   *format       = gimp_image_get_channel_format (image);
+
+          if (format != gimp_drawable_get_format (new_drawable))
+            {
+              GeglBuffer *new_buffer;
+
+              new_buffer =
+                gegl_buffer_new (GEGL_RECTANGLE (0, 0,
+                                                 gimp_item_get_width  (new_item),
+                                                 gimp_item_get_height (new_item)),
+                                 format);
+
+              gegl_buffer_set_format (new_buffer,
+                                      gimp_drawable_get_format (new_drawable));
+              gimp_gegl_buffer_copy (gimp_drawable_get_buffer (new_drawable),
+                                     NULL, GEGL_ABYSS_NONE,
+                                     new_buffer, NULL);
+              gegl_buffer_set_format (new_buffer, NULL);
+
+              gimp_drawable_set_buffer (new_drawable, FALSE, NULL, new_buffer);
+              g_object_unref (new_buffer);
+            }
+        }
+    }
+
+  return new_item;
+}
+
+static void
+gimp_channel_convert (GimpItem  *item,
+                      GimpImage *dest_image,
+                      GType      old_type)
+{
+  GimpChannel  *channel  = GIMP_CHANNEL (item);
+  GimpDrawable *drawable = GIMP_DRAWABLE (item);
+
+  if (! gimp_drawable_is_gray (drawable))
+    {
+      gimp_drawable_convert_type (drawable, dest_image,
+                                  GIMP_GRAY,
+                                  gimp_image_get_precision (dest_image),
+                                  gimp_drawable_has_alpha (drawable),
+                                  NULL,
+                                  GEGL_DITHER_NONE, GEGL_DITHER_NONE,
+                                  FALSE, NULL);
+    }
+
+  if (gimp_drawable_has_alpha (drawable))
+    {
+      GeglBuffer *new_buffer;
+      const Babl *format;
+      GimpRGB     background;
+
+      format = gimp_drawable_get_format_without_alpha (drawable);
+
+      new_buffer =
+        gegl_buffer_new (GEGL_RECTANGLE (0, 0,
+                                         gimp_item_get_width (item),
+                                         gimp_item_get_height (item)),
+                         format);
+
+      gimp_rgba_set (&background, 0.0, 0.0, 0.0, 0.0);
+
+      gimp_gegl_apply_flatten (gimp_drawable_get_buffer (drawable),
+                               NULL, NULL,
+                               new_buffer, &background,
+                               GIMP_LAYER_COLOR_SPACE_RGB_LINEAR);
+
+      gimp_drawable_set_buffer_full (drawable, FALSE, NULL,
+                                     new_buffer,
+                                     GEGL_RECTANGLE (
+                                       gimp_item_get_offset_x (item),
+                                       gimp_item_get_offset_y (item),
+                                       0, 0),
+                                     TRUE);
+      g_object_unref (new_buffer);
+    }
+
+  if (G_TYPE_FROM_INSTANCE (channel) == GIMP_TYPE_CHANNEL)
+    {
+      gint width  = gimp_image_get_width  (dest_image);
+      gint height = gimp_image_get_height (dest_image);
+
+      gimp_item_set_offset (item, 0, 0);
+
+      if (gimp_item_get_width  (item) != width ||
+          gimp_item_get_height (item) != height)
+        {
+          gimp_item_resize (item, gimp_get_user_context (dest_image->gimp),
+                            GIMP_FILL_TRANSPARENT,
+                            width, height, 0, 0);
+        }
+    }
+
+  GIMP_ITEM_CLASS (parent_class)->convert (item, dest_image, old_type);
+}
+
+static void
+gimp_channel_translate (GimpItem *item,
+                        gdouble   off_x,
+                        gdouble   off_y,
+                        gboolean  push_undo)
+{
+  GimpChannel *channel = GIMP_CHANNEL (item);
+  gint         x, y, width, height;
+
+  gimp_item_bounds (GIMP_ITEM (channel), &x, &y, &width, &height);
+
+  /*  update the old area  */
+  gimp_drawable_update (GIMP_DRAWABLE (item), x, y, width, height);
+
+  if (push_undo)
+    gimp_channel_push_undo (channel, NULL);
+
+  if (gimp_rectangle_intersect (x + SIGNED_ROUND (off_x),
+                                y + SIGNED_ROUND (off_y),
+                                width, height,
+                                0, 0,
+                                gimp_item_get_width  (GIMP_ITEM (channel)),
+                                gimp_item_get_height (GIMP_ITEM (channel)),
+                                &x, &y, &width, &height))
+    {
+      /*  copy the portion of the mask we will keep to a temporary
+       *  buffer
+       */
+      GeglBuffer *tmp_buffer =
+        gegl_buffer_new (GEGL_RECTANGLE (0, 0, width, height),
+                         gimp_drawable_get_format (GIMP_DRAWABLE (channel)));
+
+      gimp_gegl_buffer_copy (gimp_drawable_get_buffer (GIMP_DRAWABLE (channel)),
+                             GEGL_RECTANGLE (x - SIGNED_ROUND (off_x),
+                                             y - SIGNED_ROUND (off_y),
+                                             width, height),
+                             GEGL_ABYSS_NONE,
+                             tmp_buffer,
+                             GEGL_RECTANGLE (0, 0, 0, 0));
+
+      /*  clear the mask  */
+      gegl_buffer_clear (gimp_drawable_get_buffer (GIMP_DRAWABLE (channel)),
+                         NULL);
+
+      /*  copy the temp mask back to the mask  */
+      gimp_gegl_buffer_copy (tmp_buffer, NULL, GEGL_ABYSS_NONE,
+                             gimp_drawable_get_buffer (GIMP_DRAWABLE (channel)),
+                             GEGL_RECTANGLE (x, y, 0, 0));
+
+      /*  free the temporary mask  */
+      g_object_unref (tmp_buffer);
+
+      channel->x1 = x;
+      channel->y1 = y;
+      channel->x2 = x + width;
+      channel->y2 = y + height;
+    }
+  else
+    {
+      /*  clear the mask  */
+      gegl_buffer_clear (gimp_drawable_get_buffer (GIMP_DRAWABLE (channel)),
+                         NULL);
+
+      channel->empty = TRUE;
+      channel->x1    = 0;
+      channel->y1    = 0;
+      channel->x2    = gimp_item_get_width  (GIMP_ITEM (channel));
+      channel->y2    = gimp_item_get_height (GIMP_ITEM (channel));
+    }
+
+  /*  update the new area  */
+  gimp_drawable_update (GIMP_DRAWABLE (item),
+                        channel->x1, channel->y1,
+                        channel->x2 - channel->x1,
+                        channel->y2 - channel->y1);
+}
+
+static void
+gimp_channel_scale (GimpItem              *item,
+                    gint                   new_width,
+                    gint                   new_height,
+                    gint                   new_offset_x,
+                    gint                   new_offset_y,
+                    GimpInterpolationType  interpolation_type,
+                    GimpProgress          *progress)
+{
+  GimpChannel *channel = GIMP_CHANNEL (item);
+
+  if (G_TYPE_FROM_INSTANCE (item) == GIMP_TYPE_CHANNEL)
+    {
+      new_offset_x = 0;
+      new_offset_y = 0;
+    }
+
+  /*  don't waste CPU cycles scaling an empty channel  */
+  if (channel->bounds_known && channel->empty)
+    {
+      GimpDrawable *drawable = GIMP_DRAWABLE (item);
+      GeglBuffer   *new_buffer;
+
+      new_buffer =
+        gegl_buffer_new (GEGL_RECTANGLE (0, 0, new_width, new_height),
+                         gimp_drawable_get_format (drawable));
+
+      gimp_drawable_set_buffer_full (drawable,
+                                     gimp_item_is_attached (item), NULL,
+                                     new_buffer,
+                                     GEGL_RECTANGLE (new_offset_x, new_offset_y,
+                                                     0,            0),
+                                     TRUE);
+      g_object_unref (new_buffer);
+
+      gimp_channel_clear (GIMP_CHANNEL (item), NULL, FALSE);
+    }
+  else
+    {
+      GIMP_ITEM_CLASS (parent_class)->scale (item, new_width, new_height,
+                                             new_offset_x, new_offset_y,
+                                             interpolation_type, progress);
+    }
+}
+
+static void
+gimp_channel_resize (GimpItem     *item,
+                     GimpContext  *context,
+                     GimpFillType  fill_type,
+                     gint          new_width,
+                     gint          new_height,
+                     gint          offset_x,
+                     gint          offset_y)
+{
+  GIMP_ITEM_CLASS (parent_class)->resize (item, context, GIMP_FILL_TRANSPARENT,
+                                          new_width, new_height,
+                                          offset_x, offset_y);
+
+  if (G_TYPE_FROM_INSTANCE (item) == GIMP_TYPE_CHANNEL)
+    {
+      gimp_item_set_offset (item, 0, 0);
+    }
+}
+
+static GimpTransformResize
+gimp_channel_get_clip (GimpItem            *item,
+                       GimpTransformResize  clip_result)
+{
+  return GIMP_TRANSFORM_RESIZE_CLIP;
+}
+
+static gboolean
+gimp_channel_fill (GimpItem         *item,
+                   GimpDrawable     *drawable,
+                   GimpFillOptions  *fill_options,
+                   gboolean          push_undo,
+                   GimpProgress     *progress,
+                   GError          **error)
+{
+  GimpChannel        *channel = GIMP_CHANNEL (item);
+  const GimpBoundSeg *segs_in;
+  const GimpBoundSeg *segs_out;
+  gint                n_segs_in;
+  gint                n_segs_out;
+  gint                offset_x, offset_y;
+
+  if (! gimp_channel_boundary (channel, &segs_in, &segs_out,
+                               &n_segs_in, &n_segs_out,
+                               0, 0, 0, 0))
+    {
+      g_set_error_literal (error, GIMP_ERROR, GIMP_FAILED,
+                           _("Cannot fill empty channel."));
+      return FALSE;
+    }
+
+  gimp_item_get_offset (item, &offset_x, &offset_y);
+
+  gimp_drawable_fill_boundary (drawable,
+                               fill_options,
+                               segs_in, n_segs_in,
+                               offset_x, offset_y,
+                               push_undo);
+
+  return TRUE;
+}
+
+static gboolean
+gimp_channel_stroke (GimpItem           *item,
+                     GimpDrawable       *drawable,
+                     GimpStrokeOptions  *stroke_options,
+                     gboolean            push_undo,
+                     GimpProgress       *progress,
+                     GError            **error)
+{
+  GimpChannel        *channel = GIMP_CHANNEL (item);
+  const GimpBoundSeg *segs_in;
+  const GimpBoundSeg *segs_out;
+  gint                n_segs_in;
+  gint                n_segs_out;
+  gboolean            retval = FALSE;
+  gint                offset_x, offset_y;
+
+  if (! gimp_channel_boundary (channel, &segs_in, &segs_out,
+                               &n_segs_in, &n_segs_out,
+                               0, 0, 0, 0))
+    {
+      g_set_error_literal (error, GIMP_ERROR, GIMP_FAILED,
+                           _("Cannot stroke empty channel."));
+      return FALSE;
+    }
+
+  gimp_item_get_offset (item, &offset_x, &offset_y);
+
+  switch (gimp_stroke_options_get_method (stroke_options))
+    {
+    case GIMP_STROKE_LINE:
+      gimp_drawable_stroke_boundary (drawable,
+                                     stroke_options,
+                                     segs_in, n_segs_in,
+                                     offset_x, offset_y,
+                                     push_undo);
+      retval = TRUE;
+      break;
+
+    case GIMP_STROKE_PAINT_METHOD:
+      {
+        GimpPaintInfo    *paint_info;
+        GimpPaintCore    *core;
+        GimpPaintOptions *paint_options;
+        gboolean          emulate_dynamics;
+
+        paint_info = gimp_context_get_paint_info (GIMP_CONTEXT (stroke_options));
+
+        core = g_object_new (paint_info->paint_type, NULL);
+
+        paint_options = gimp_stroke_options_get_paint_options (stroke_options);
+        emulate_dynamics = gimp_stroke_options_get_emulate_dynamics (stroke_options);
+
+        retval = gimp_paint_core_stroke_boundary (core, drawable,
+                                                  paint_options,
+                                                  emulate_dynamics,
+                                                  segs_in, n_segs_in,
+                                                  offset_x, offset_y,
+                                                  push_undo, error);
+
+        g_object_unref (core);
+      }
+      break;
+
+    default:
+      g_return_val_if_reached (FALSE);
+    }
+
+  return retval;
+}
+
+static void
+gimp_channel_to_selection (GimpItem       *item,
+                           GimpChannelOps  op,
+                           gboolean        antialias,
+                           gboolean        feather,
+                           gdouble         feather_radius_x,
+                           gdouble         feather_radius_y)
+{
+  GimpChannel *channel = GIMP_CHANNEL (item);
+  GimpImage   *image   = gimp_item_get_image (item);
+  gint         off_x, off_y;
+
+  gimp_item_get_offset (item, &off_x, &off_y);
+
+  gimp_channel_select_channel (gimp_image_get_mask (image),
+                               GIMP_ITEM_GET_CLASS (item)->to_selection_desc,
+                               channel, off_x, off_y,
+                               op,
+                               feather, feather_radius_x, feather_radius_x);
+}
+
+static void
+gimp_channel_convert_type (GimpDrawable     *drawable,
+                           GimpImage        *dest_image,
+                           const Babl       *new_format,
+                           GimpColorProfile *dest_profile,
+                           GeglDitherMethod  layer_dither_type,
+                           GeglDitherMethod  mask_dither_type,
+                           gboolean          push_undo,
+                           GimpProgress     *progress)
+{
+  GeglBuffer *dest_buffer;
+
+  dest_buffer =
+    gegl_buffer_new (GEGL_RECTANGLE (0, 0,
+                                     gimp_item_get_width  (GIMP_ITEM (drawable)),
+                                     gimp_item_get_height (GIMP_ITEM (drawable))),
+                     new_format);
+
+  if (mask_dither_type == GEGL_DITHER_NONE)
+    {
+      gimp_gegl_buffer_copy (gimp_drawable_get_buffer (drawable), NULL,
+                             GEGL_ABYSS_NONE,
+                             dest_buffer, NULL);
+    }
+  else
+    {
+      gint bits;
+
+      bits = (babl_format_get_bytes_per_pixel (new_format) * 8 /
+              babl_format_get_n_components (new_format));
+
+      gimp_gegl_apply_dither (gimp_drawable_get_buffer (drawable),
+                              NULL, NULL,
+                              dest_buffer, 1 << bits, mask_dither_type);
+    }
+
+  gimp_drawable_set_buffer (drawable, push_undo, NULL, dest_buffer);
+  g_object_unref (dest_buffer);
+}
+
+static void
+gimp_channel_invalidate_boundary (GimpDrawable *drawable)
+{
+  GimpChannel *channel = GIMP_CHANNEL (drawable);
+
+  channel->boundary_known = FALSE;
+  channel->bounds_known   = FALSE;
+}
+
+static void
+gimp_channel_get_active_components (GimpDrawable *drawable,
+                                    gboolean     *active)
+{
+  /*  Make sure that the alpha channel is not valid.  */
+  active[GRAY]    = TRUE;
+  active[ALPHA_G] = FALSE;
+}
+
+static void
+gimp_channel_set_buffer (GimpDrawable        *drawable,
+                         gboolean             push_undo,
+                         const gchar         *undo_desc,
+                         GeglBuffer          *buffer,
+                         const GeglRectangle *bounds)
+{
+  GimpChannel *channel    = GIMP_CHANNEL (drawable);
+  GeglBuffer  *old_buffer = gimp_drawable_get_buffer (drawable);
+
+  if (old_buffer)
+    {
+      g_signal_handlers_disconnect_by_func (old_buffer,
+                                            gimp_channel_buffer_changed,
+                                            channel);
+    }
+
+  GIMP_DRAWABLE_CLASS (parent_class)->set_buffer (drawable,
+                                                  push_undo, undo_desc,
+                                                  buffer, bounds);
+
+  gegl_buffer_signal_connect (buffer, "changed",
+                              G_CALLBACK (gimp_channel_buffer_changed),
+                              channel);
+
+  if (gimp_filter_peek_node (GIMP_FILTER (channel)))
+    {
+      const Babl *color_format;
+
+      if (gimp_drawable_get_linear (drawable))
+        color_format = babl_format ("RGBA float");
+      else
+        color_format = babl_format ("R'G'B'A float");
+
+      gegl_node_set (channel->color_node,
+                     "format", color_format,
+                     NULL);
+    }
+}
+
+static gdouble
+gimp_channel_get_opacity_at (GimpPickable *pickable,
+                             gint          x,
+                             gint          y)
+{
+  GimpChannel *channel = GIMP_CHANNEL (pickable);
+  gdouble      value   = GIMP_OPACITY_TRANSPARENT;
+
+  if (x >= 0 && x < gimp_item_get_width  (GIMP_ITEM (channel)) &&
+      y >= 0 && y < gimp_item_get_height (GIMP_ITEM (channel)))
+    {
+      if (! channel->bounds_known ||
+          (! channel->empty &&
+           x >= channel->x1 &&
+           x <  channel->x2 &&
+           y >= channel->y1 &&
+           y <  channel->y2))
+        {
+          gegl_buffer_sample (gimp_drawable_get_buffer (GIMP_DRAWABLE (channel)),
+                              x, y, NULL, &value, babl_format ("Y double"),
+                              GEGL_SAMPLER_NEAREST, GEGL_ABYSS_NONE);
+        }
+    }
+
+  return value;
+}
+
+static gboolean
+gimp_channel_real_boundary (GimpChannel         *channel,
+                            const GimpBoundSeg **segs_in,
+                            const GimpBoundSeg **segs_out,
+                            gint                *num_segs_in,
+                            gint                *num_segs_out,
+                            gint                 x1,
+                            gint                 y1,
+                            gint                 x2,
+                            gint                 y2)
+{
+  if (! channel->boundary_known)
+    {
+      gint x3, y3, x4, y4;
+
+      /* free the out of date boundary segments */
+      g_free (channel->segs_in);
+      g_free (channel->segs_out);
+
+      if (gimp_item_bounds (GIMP_ITEM (channel), &x3, &y3, &x4, &y4))
+        {
+          GeglBuffer    *buffer;
+          GeglRectangle  rect = { x3, y3, x4, y4 };
+
+          x4 += x3;
+          y4 += y3;
+
+          buffer = gimp_drawable_get_buffer (GIMP_DRAWABLE (channel));
+
+          channel->segs_out = gimp_boundary_find (buffer, &rect,
+                                                  babl_format ("Y float"),
+                                                  GIMP_BOUNDARY_IGNORE_BOUNDS,
+                                                  x1, y1, x2, y2,
+                                                  GIMP_BOUNDARY_HALF_WAY,
+                                                  &channel->num_segs_out);
+          x1 = MAX (x1, x3);
+          y1 = MAX (y1, y3);
+          x2 = MIN (x2, x4);
+          y2 = MIN (y2, y4);
+
+          if (x2 > x1 && y2 > y1)
+            {
+              channel->segs_in = gimp_boundary_find (buffer, NULL,
+                                                     babl_format ("Y float"),
+                                                     GIMP_BOUNDARY_WITHIN_BOUNDS,
+                                                     x1, y1, x2, y2,
+                                                     GIMP_BOUNDARY_HALF_WAY,
+                                                     &channel->num_segs_in);
+            }
+          else
+            {
+              channel->segs_in     = NULL;
+              channel->num_segs_in = 0;
+            }
+        }
+      else
+        {
+          channel->segs_in      = NULL;
+          channel->segs_out     = NULL;
+          channel->num_segs_in  = 0;
+          channel->num_segs_out = 0;
+        }
+
+      channel->boundary_known = TRUE;
+    }
+
+  *segs_in      = channel->segs_in;
+  *segs_out     = channel->segs_out;
+  *num_segs_in  = channel->num_segs_in;
+  *num_segs_out = channel->num_segs_out;
+
+  return (! channel->empty);
+}
+
+static gboolean
+gimp_channel_real_is_empty (GimpChannel *channel)
+{
+  GeglBuffer *buffer;
+
+  if (channel->bounds_known)
+    return channel->empty;
+
+  buffer = gimp_drawable_get_buffer (GIMP_DRAWABLE (channel));
+
+  if (! gimp_gegl_mask_is_empty (buffer))
+    return FALSE;
+
+  /*  The mask is empty, meaning we can set the bounds as known  */
+  g_clear_pointer (&channel->segs_in,  g_free);
+  g_clear_pointer (&channel->segs_out, g_free);
+
+  channel->empty          = TRUE;
+  channel->num_segs_in    = 0;
+  channel->num_segs_out   = 0;
+  channel->bounds_known   = TRUE;
+  channel->boundary_known = TRUE;
+  channel->x1             = 0;
+  channel->y1             = 0;
+  channel->x2             = gimp_item_get_width  (GIMP_ITEM (channel));
+  channel->y2             = gimp_item_get_height (GIMP_ITEM (channel));
+
+  return TRUE;
+}
+
+static void
+gimp_channel_real_feather (GimpChannel *channel,
+                           gdouble      radius_x,
+                           gdouble      radius_y,
+                           gboolean     edge_lock,
+                           gboolean     push_undo)
+{
+  gint x1, y1, x2, y2;
+
+  if (radius_x <= 0.0 && radius_y <= 0.0)
+    return;
+
+  if (! gimp_item_bounds (GIMP_ITEM (channel), &x1, &y1, &x2, &y2))
+    return;
+
+  x2 += x1;
+  y2 += y1;
+
+  if (gimp_channel_is_empty (channel))
+    return;
+
+  x1 = MAX (0, x1 - ceil (radius_x));
+  y1 = MAX (0, y1 - ceil (radius_y));
+
+  x2 = MIN (gimp_item_get_width  (GIMP_ITEM (channel)), x2 + ceil (radius_x));
+  y2 = MIN (gimp_item_get_height (GIMP_ITEM (channel)), y2 + ceil (radius_y));
+
+  if (push_undo)
+    gimp_channel_push_undo (channel,
+                            GIMP_CHANNEL_GET_CLASS (channel)->feather_desc);
+
+  gimp_gegl_apply_feather (gimp_drawable_get_buffer (GIMP_DRAWABLE (channel)),
+                           NULL, NULL,
+                           gimp_drawable_get_buffer (GIMP_DRAWABLE (channel)),
+                           GEGL_RECTANGLE (x1, y1, x2 - x1, y2 - y1),
+                           radius_x,
+                           radius_y,
+                           edge_lock);
+
+  gimp_drawable_update (GIMP_DRAWABLE (channel), 0, 0, -1, -1);
+}
+
+static void
+gimp_channel_real_sharpen (GimpChannel *channel,
+                           gboolean     push_undo)
+{
+  GimpDrawable *drawable = GIMP_DRAWABLE (channel);
+
+  if (push_undo)
+    gimp_channel_push_undo (channel,
+                            GIMP_CHANNEL_GET_CLASS (channel)->sharpen_desc);
+
+  gimp_gegl_apply_threshold (gimp_drawable_get_buffer (drawable),
+                             NULL, NULL,
+                             gimp_drawable_get_buffer (drawable),
+                             0.5);
+
+  gimp_drawable_update (GIMP_DRAWABLE (channel), 0, 0, -1, -1);
+}
+
+static void
+gimp_channel_real_clear (GimpChannel *channel,
+                         const gchar *undo_desc,
+                         gboolean     push_undo)
+{
+  GeglBuffer    *buffer;
+  GeglRectangle  rect;
+  GeglRectangle  aligned_rect;
+
+  if (channel->bounds_known && channel->empty)
+    return;
+
+  if (push_undo)
+    {
+      if (! undo_desc)
+        undo_desc = GIMP_CHANNEL_GET_CLASS (channel)->clear_desc;
+
+      gimp_channel_push_undo (channel, undo_desc);
+    }
+
+  buffer = gimp_drawable_get_buffer (GIMP_DRAWABLE (channel));
+
+  if (channel->bounds_known)
+    {
+      rect.x      = channel->x1;
+      rect.y      = channel->y1;
+      rect.width  = channel->x2 - channel->x1;
+      rect.height = channel->y2 - channel->y1;
+    }
+  else
+    {
+      rect.x      = 0;
+      rect.y      = 0;
+      rect.width  = gimp_item_get_width  (GIMP_ITEM (channel));
+      rect.height = gimp_item_get_height (GIMP_ITEM (channel));
+    }
+
+  gegl_rectangle_align_to_buffer (&aligned_rect, &rect, buffer,
+                                  GEGL_RECTANGLE_ALIGNMENT_SUPERSET);
+
+  gegl_buffer_clear (buffer, &aligned_rect);
+
+  /*  we know the bounds  */
+  channel->bounds_known = TRUE;
+  channel->empty        = TRUE;
+  channel->x1           = 0;
+  channel->y1           = 0;
+  channel->x2           = gimp_item_get_width  (GIMP_ITEM (channel));
+  channel->y2           = gimp_item_get_height (GIMP_ITEM (channel));
+
+  gimp_drawable_update (GIMP_DRAWABLE (channel),
+                        rect.x, rect.y, rect.width, rect.height);
+}
+
+static void
+gimp_channel_real_all (GimpChannel *channel,
+                       gboolean     push_undo)
+{
+  GeglColor *color;
+
+  if (push_undo)
+    gimp_channel_push_undo (channel,
+                            GIMP_CHANNEL_GET_CLASS (channel)->all_desc);
+
+  /*  clear the channel  */
+  color = gegl_color_new ("#fff");
+  gegl_buffer_set_color (gimp_drawable_get_buffer (GIMP_DRAWABLE (channel)),
+                         NULL, color);
+  g_object_unref (color);
+
+  /*  we know the bounds  */
+  channel->bounds_known = TRUE;
+  channel->empty        = FALSE;
+  channel->x1           = 0;
+  channel->y1           = 0;
+  channel->x2           = gimp_item_get_width  (GIMP_ITEM (channel));
+  channel->y2           = gimp_item_get_height (GIMP_ITEM (channel));
+
+  gimp_drawable_update (GIMP_DRAWABLE (channel), 0, 0, -1, -1);
+}
+
+static void
+gimp_channel_real_invert (GimpChannel *channel,
+                          gboolean     push_undo)
+{
+  GimpDrawable *drawable = GIMP_DRAWABLE (channel);
+
+  if (push_undo)
+    gimp_channel_push_undo (channel,
+                            GIMP_CHANNEL_GET_CLASS (channel)->invert_desc);
+
+  if (channel->bounds_known && channel->empty)
+    {
+      gimp_channel_all (channel, FALSE);
+    }
+  else
+    {
+      gimp_gegl_apply_invert_linear (gimp_drawable_get_buffer (drawable),
+                                     NULL, NULL,
+                                     gimp_drawable_get_buffer (drawable));
+
+      gimp_drawable_update (GIMP_DRAWABLE (channel), 0, 0, -1, -1);
+    }
+}
+
+static void
+gimp_channel_real_border (GimpChannel            *channel,
+                          gint                    radius_x,
+                          gint                    radius_y,
+                          GimpChannelBorderStyle  style,
+                          gboolean                edge_lock,
+                          gboolean                push_undo)
+{
+  gint x1, y1, x2, y2;
+
+  if (radius_x == 0 && radius_y == 0)
+    {
+      /* The relevant GEGL operations require radius_x and radius_y to be > 0.
+       * When both are 0 (currently can only be achieved by the user through
+       * PDB), the effect should be to clear the channel.
+       */
+      gimp_channel_clear (channel,
+                          GIMP_CHANNEL_GET_CLASS (channel)->border_desc,
+                          push_undo);
+      return;
+    }
+  else if (radius_x <= 0 || radius_y <= 0)
+    {
+      /* FIXME: Implement the case where only one of radius_x and radius_y is 0.
+       * Currently, should never happen.
+       */
+      g_return_if_reached();
+    }
+
+  if (! gimp_item_bounds (GIMP_ITEM (channel), &x1, &y1, &x2, &y2))
+    return;
+
+  x2 += x1;
+  y2 += y1;
+
+  if (gimp_channel_is_empty (channel))
+    return;
+
+  if (x1 - radius_x < 0)
+    x1 = 0;
+  else
+    x1 -= radius_x;
+
+  if (x2 + radius_x > gimp_item_get_width (GIMP_ITEM (channel)))
+    x2 = gimp_item_get_width (GIMP_ITEM (channel));
+  else
+    x2 += radius_x;
+
+  if (y1 - radius_y < 0)
+    y1 = 0;
+  else
+    y1 -= radius_y;
+
+  if (y2 + radius_y > gimp_item_get_height (GIMP_ITEM (channel)))
+    y2 = gimp_item_get_height (GIMP_ITEM (channel));
+  else
+    y2 += radius_y;
+
+  if (push_undo)
+    gimp_channel_push_undo (channel,
+                            GIMP_CHANNEL_GET_CLASS (channel)->border_desc);
+
+  gimp_gegl_apply_border (gimp_drawable_get_buffer (GIMP_DRAWABLE (channel)),
+                          NULL, NULL,
+                          gimp_drawable_get_buffer (GIMP_DRAWABLE (channel)),
+                          GEGL_RECTANGLE (x1, y1, x2 - x1, y2 - y1),
+                          radius_x, radius_y, style, edge_lock);
+
+  gimp_drawable_update (GIMP_DRAWABLE (channel), 0, 0, -1, -1);
+}
+
+static void
+gimp_channel_real_grow (GimpChannel *channel,
+                        gint         radius_x,
+                        gint         radius_y,
+                        gboolean     push_undo)
+{
+  gint x1, y1, x2, y2;
+
+  if (radius_x == 0 && radius_y == 0)
+    return;
+
+  if (radius_x <= 0 && radius_y <= 0)
+    {
+      gimp_channel_shrink (channel, -radius_x, -radius_y, FALSE, push_undo);
+      return;
+    }
+
+  if (radius_x < 0 || radius_y < 0)
+    return;
+
+  if (! gimp_item_bounds (GIMP_ITEM (channel), &x1, &y1, &x2, &y2))
+    return;
+
+  x2 += x1;
+  y2 += y1;
+
+  if (gimp_channel_is_empty (channel))
+    return;
+
+  if (x1 - radius_x > 0)
+    x1 = x1 - radius_x;
+  else
+    x1 = 0;
+
+  if (y1 - radius_y > 0)
+    y1 = y1 - radius_y;
+  else
+    y1 = 0;
+
+  if (x2 + radius_x < gimp_item_get_width (GIMP_ITEM (channel)))
+    x2 = x2 + radius_x;
+  else
+    x2 = gimp_item_get_width (GIMP_ITEM (channel));
+
+  if (y2 + radius_y < gimp_item_get_height (GIMP_ITEM (channel)))
+    y2 = y2 + radius_y;
+  else
+    y2 = gimp_item_get_height (GIMP_ITEM (channel));
+
+  if (push_undo)
+    gimp_channel_push_undo (channel,
+                            GIMP_CHANNEL_GET_CLASS (channel)->grow_desc);
+
+  gimp_gegl_apply_grow (gimp_drawable_get_buffer (GIMP_DRAWABLE (channel)),
+                        NULL, NULL,
+                        gimp_drawable_get_buffer (GIMP_DRAWABLE (channel)),
+                        GEGL_RECTANGLE (x1, y1, x2 - x1, y2 - y1),
+                        radius_x, radius_y);
+
+  gimp_drawable_update (GIMP_DRAWABLE (channel), 0, 0, -1, -1);
+}
+
+static void
+gimp_channel_real_shrink (GimpChannel *channel,
+                          gint         radius_x,
+                          gint         radius_y,
+                          gboolean     edge_lock,
+                          gboolean     push_undo)
+{
+  gint x1, y1, x2, y2;
+
+  if (radius_x == 0 && radius_y == 0)
+    return;
+
+  if (radius_x <= 0 && radius_y <= 0)
+    {
+      gimp_channel_grow (channel, -radius_x, -radius_y, push_undo);
+      return;
+    }
+
+  if (radius_x < 0 || radius_y < 0)
+    return;
+
+  if (! gimp_item_bounds (GIMP_ITEM (channel), &x1, &y1, &x2, &y2))
+    return;
+
+  x2 += x1;
+  y2 += y1;
+
+  if (gimp_channel_is_empty (channel))
+    return;
+
+  if (x1 > 0)
+    x1--;
+  if (y1 > 0)
+    y1--;
+  if (x2 < gimp_item_get_width (GIMP_ITEM (channel)))
+    x2++;
+  if (y2 < gimp_item_get_height (GIMP_ITEM (channel)))
+    y2++;
+
+  if (push_undo)
+    gimp_channel_push_undo (channel,
+                            GIMP_CHANNEL_GET_CLASS (channel)->shrink_desc);
+
+  gimp_gegl_apply_shrink (gimp_drawable_get_buffer (GIMP_DRAWABLE (channel)),
+                          NULL, NULL,
+                          gimp_drawable_get_buffer (GIMP_DRAWABLE (channel)),
+                          GEGL_RECTANGLE (x1, y1, x2 - x1, y2 - y1),
+                          radius_x, radius_y, edge_lock);
+
+  gimp_drawable_update (GIMP_DRAWABLE (channel), 0, 0, -1, -1);
+}
+
+static void
+gimp_channel_real_flood (GimpChannel *channel,
+                         gboolean     push_undo)
+{
+  gint x, y, width, height;
+
+  if (! gimp_item_bounds (GIMP_ITEM (channel), &x, &y, &width, &height))
+    return;
+
+  if (gimp_channel_is_empty (channel))
+    return;
+
+  if (push_undo)
+    gimp_channel_push_undo (channel,
+                            GIMP_CHANNEL_GET_CLASS (channel)->flood_desc);
+
+  gimp_gegl_apply_flood (gimp_drawable_get_buffer (GIMP_DRAWABLE (channel)),
+                         NULL, NULL,
+                         gimp_drawable_get_buffer (GIMP_DRAWABLE (channel)),
+                         GEGL_RECTANGLE (x, y, width, height));
+
+  gimp_drawable_update (GIMP_DRAWABLE (channel), x, y, width, height);
+}
+
+static void
+gimp_channel_buffer_changed (GeglBuffer          *buffer,
+                             const GeglRectangle *rect,
+                             GimpChannel         *channel)
+{
+  gimp_drawable_invalidate_boundary (GIMP_DRAWABLE (channel));
+}
+
+
+/*  public functions  */
+
+GimpChannel *
+gimp_channel_new (GimpImage     *image,
+                  gint           width,
+                  gint           height,
+                  const gchar   *name,
+                  const GimpRGB *color)
+{
+  GimpChannel *channel;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  channel =
+    GIMP_CHANNEL (gimp_drawable_new (GIMP_TYPE_CHANNEL,
+                                     image, name,
+                                     0, 0, width, height,
+                                     gimp_image_get_channel_format (image)));
+
+  if (color)
+    channel->color = *color;
+
+  channel->show_masked = TRUE;
+
+  /*  selection mask variables  */
+  channel->x2          = width;
+  channel->y2          = height;
+
+  return channel;
+}
+
+GimpChannel *
+gimp_channel_new_from_buffer (GimpImage     *image,
+                              GeglBuffer    *buffer,
+                              const gchar   *name,
+                              const GimpRGB *color)
+{
+  GimpChannel *channel;
+  GeglBuffer  *dest;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GEGL_IS_BUFFER (buffer), NULL);
+
+  channel = gimp_channel_new (image,
+                              gegl_buffer_get_width  (buffer),
+                              gegl_buffer_get_height (buffer),
+                              name, color);
+
+  dest = gimp_drawable_get_buffer (GIMP_DRAWABLE (channel));
+  gimp_gegl_buffer_copy (buffer, NULL, GEGL_ABYSS_NONE, dest, NULL);
+
+  return channel;
+}
+
+GimpChannel *
+gimp_channel_new_from_alpha (GimpImage     *image,
+                             GimpDrawable  *drawable,
+                             const gchar   *name,
+                             const GimpRGB *color)
+{
+  GimpChannel *channel;
+  GeglBuffer  *dest_buffer;
+  gint         width;
+  gint         height;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
+  g_return_val_if_fail (gimp_drawable_has_alpha (drawable), NULL);
+
+  width  = gimp_item_get_width  (GIMP_ITEM (drawable));
+  height = gimp_item_get_height (GIMP_ITEM (drawable));
+
+  channel = gimp_channel_new (image, width, height, name, color);
+
+  gimp_channel_clear (channel, NULL, FALSE);
+
+  dest_buffer = gimp_drawable_get_buffer (GIMP_DRAWABLE (channel));
+
+  gegl_buffer_set_format (dest_buffer,
+                          gimp_drawable_get_component_format (drawable,
+                                                              GIMP_CHANNEL_ALPHA));
+  gimp_gegl_buffer_copy (gimp_drawable_get_buffer (drawable), NULL,
+                         GEGL_ABYSS_NONE,
+                         dest_buffer, NULL);
+  gegl_buffer_set_format (dest_buffer, NULL);
+
+  return channel;
+}
+
+GimpChannel *
+gimp_channel_new_from_component (GimpImage       *image,
+                                 GimpChannelType  type,
+                                 const gchar     *name,
+                                 const GimpRGB   *color)
+{
+  GimpChannel *channel;
+  GeglBuffer  *src_buffer;
+  GeglBuffer  *dest_buffer;
+  gint         width;
+  gint         height;
+  const Babl  *format;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  format = gimp_image_get_component_format (image, type);
+
+  g_return_val_if_fail (format != NULL, NULL);
+
+  gimp_pickable_flush (GIMP_PICKABLE (image));
+
+  src_buffer = gimp_pickable_get_buffer (GIMP_PICKABLE (image));
+  width  = gegl_buffer_get_width  (src_buffer);
+  height = gegl_buffer_get_height (src_buffer);
+
+  channel = gimp_channel_new (image, width, height, name, color);
+
+  dest_buffer = gimp_drawable_get_buffer (GIMP_DRAWABLE (channel));
+
+  gegl_buffer_set_format (dest_buffer, format);
+  gimp_gegl_buffer_copy (src_buffer, NULL, GEGL_ABYSS_NONE, dest_buffer, NULL);
+  gegl_buffer_set_format (dest_buffer, NULL);
+
+  return channel;
+}
+
+GimpChannel *
+gimp_channel_get_parent (GimpChannel *channel)
+{
+  g_return_val_if_fail (GIMP_IS_CHANNEL (channel), NULL);
+
+  return GIMP_CHANNEL (gimp_viewable_get_parent (GIMP_VIEWABLE (channel)));
+}
+
+void
+gimp_channel_set_color (GimpChannel   *channel,
+                        const GimpRGB *color,
+                        gboolean       push_undo)
+{
+  g_return_if_fail (GIMP_IS_CHANNEL (channel));
+  g_return_if_fail (color != NULL);
+
+  if (gimp_rgba_distance (&channel->color, color) > RGBA_EPSILON)
+    {
+      if (push_undo && gimp_item_is_attached (GIMP_ITEM (channel)))
+        {
+          GimpImage *image = gimp_item_get_image (GIMP_ITEM (channel));
+
+          gimp_image_undo_push_channel_color (image, C_("undo-type", "Set Channel Color"),
+                                              channel);
+        }
+
+      channel->color = *color;
+
+      if (gimp_filter_peek_node (GIMP_FILTER (channel)))
+        {
+          gimp_gegl_node_set_color (channel->color_node,
+                                    &channel->color);
+        }
+
+      gimp_drawable_update (GIMP_DRAWABLE (channel), 0, 0, -1, -1);
+
+      g_signal_emit (channel, channel_signals[COLOR_CHANGED], 0);
+    }
+}
+
+void
+gimp_channel_get_color (GimpChannel *channel,
+                        GimpRGB     *color)
+{
+  g_return_if_fail (GIMP_IS_CHANNEL (channel));
+  g_return_if_fail (color != NULL);
+
+  *color = channel->color;
+}
+
+gdouble
+gimp_channel_get_opacity (GimpChannel *channel)
+{
+  g_return_val_if_fail (GIMP_IS_CHANNEL (channel), GIMP_OPACITY_TRANSPARENT);
+
+  return channel->color.a;
+}
+
+void
+gimp_channel_set_opacity (GimpChannel *channel,
+                          gdouble      opacity,
+                          gboolean     push_undo)
+{
+  g_return_if_fail (GIMP_IS_CHANNEL (channel));
+
+  opacity = CLAMP (opacity, GIMP_OPACITY_TRANSPARENT, GIMP_OPACITY_OPAQUE);
+
+  if (channel->color.a != opacity)
+    {
+      if (push_undo && gimp_item_is_attached (GIMP_ITEM (channel)))
+        {
+          GimpImage *image = gimp_item_get_image (GIMP_ITEM (channel));
+
+          gimp_image_undo_push_channel_color (image, C_("undo-type", "Set Channel Opacity"),
+                                              channel);
+        }
+
+      channel->color.a = opacity;
+
+      if (gimp_filter_peek_node (GIMP_FILTER (channel)))
+        {
+          gimp_gegl_node_set_color (channel->color_node,
+                                    &channel->color);
+        }
+
+      gimp_drawable_update (GIMP_DRAWABLE (channel), 0, 0, -1, -1);
+
+      g_signal_emit (channel, channel_signals[COLOR_CHANGED], 0);
+    }
+}
+
+gboolean
+gimp_channel_get_show_masked (GimpChannel *channel)
+{
+  g_return_val_if_fail (GIMP_IS_CHANNEL (channel), FALSE);
+
+  return channel->show_masked;
+}
+
+void
+gimp_channel_set_show_masked (GimpChannel *channel,
+                              gboolean     show_masked)
+{
+  g_return_if_fail (GIMP_IS_CHANNEL (channel));
+
+  if (show_masked != channel->show_masked)
+    {
+      channel->show_masked = show_masked ? TRUE : FALSE;
+
+      if (channel->invert_node)
+        {
+          GeglNode *source;
+
+          source = gimp_drawable_get_source_node (GIMP_DRAWABLE (channel));
+
+          if (channel->show_masked)
+            {
+              gegl_node_connect_to (source,               "output",
+                                    channel->invert_node, "input");
+              gegl_node_connect_to (channel->invert_node, "output",
+                                    channel->mask_node,   "aux");
+            }
+          else
+            {
+              gegl_node_disconnect (channel->invert_node, "input");
+
+              gegl_node_connect_to (source,             "output",
+                                    channel->mask_node, "aux");
+            }
+        }
+
+      gimp_drawable_update (GIMP_DRAWABLE (channel), 0, 0, -1, -1);
+    }
+}
+
+void
+gimp_channel_push_undo (GimpChannel *channel,
+                        const gchar *undo_desc)
+{
+  g_return_if_fail (GIMP_IS_CHANNEL (channel));
+  g_return_if_fail (gimp_item_is_attached (GIMP_ITEM (channel)));
+
+  gimp_image_undo_push_mask (gimp_item_get_image (GIMP_ITEM (channel)),
+                             undo_desc, channel);
+}
+
+
+/******************************/
+/*  selection mask functions  */
+/******************************/
+
+GimpChannel *
+gimp_channel_new_mask (GimpImage *image,
+                       gint       width,
+                       gint       height)
+{
+  GimpChannel *channel;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  channel =
+    GIMP_CHANNEL (gimp_drawable_new (GIMP_TYPE_CHANNEL,
+                                     image, _("Selection Mask"),
+                                     0, 0, width, height,
+                                     gimp_image_get_mask_format (image)));
+
+  channel->show_masked = TRUE;
+  channel->x2          = width;
+  channel->y2          = height;
+
+  gegl_buffer_clear (gimp_drawable_get_buffer (GIMP_DRAWABLE (channel)),
+                     NULL);
+
+  return channel;
+}
+
+gboolean
+gimp_channel_boundary (GimpChannel         *channel,
+                       const GimpBoundSeg **segs_in,
+                       const GimpBoundSeg **segs_out,
+                       gint                *num_segs_in,
+                       gint                *num_segs_out,
+                       gint                 x1,
+                       gint                 y1,
+                       gint                 x2,
+                       gint                 y2)
+{
+  g_return_val_if_fail (GIMP_IS_CHANNEL (channel), FALSE);
+  g_return_val_if_fail (segs_in != NULL, FALSE);
+  g_return_val_if_fail (segs_out != NULL, FALSE);
+  g_return_val_if_fail (num_segs_in != NULL, FALSE);
+  g_return_val_if_fail (num_segs_out != NULL, FALSE);
+
+  return GIMP_CHANNEL_GET_CLASS (channel)->boundary (channel,
+                                                     segs_in, segs_out,
+                                                     num_segs_in, num_segs_out,
+                                                     x1, y1,
+                                                     x2, y2);
+}
+
+gboolean
+gimp_channel_is_empty (GimpChannel *channel)
+{
+  g_return_val_if_fail (GIMP_IS_CHANNEL (channel), TRUE);
+
+  return GIMP_CHANNEL_GET_CLASS (channel)->is_empty (channel);
+}
+
+void
+gimp_channel_feather (GimpChannel *channel,
+                      gdouble      radius_x,
+                      gdouble      radius_y,
+                      gboolean     edge_lock,
+                      gboolean     push_undo)
+{
+  g_return_if_fail (GIMP_IS_CHANNEL (channel));
+
+  if (! gimp_item_is_attached (GIMP_ITEM (channel)))
+    push_undo = FALSE;
+
+  GIMP_CHANNEL_GET_CLASS (channel)->feather (channel, radius_x, radius_y,
+                                             edge_lock, push_undo);
+}
+
+void
+gimp_channel_sharpen (GimpChannel *channel,
+                      gboolean     push_undo)
+{
+  g_return_if_fail (GIMP_IS_CHANNEL (channel));
+
+  if (! gimp_item_is_attached (GIMP_ITEM (channel)))
+    push_undo = FALSE;
+
+  GIMP_CHANNEL_GET_CLASS (channel)->sharpen (channel, push_undo);
+}
+
+void
+gimp_channel_clear (GimpChannel *channel,
+                    const gchar *undo_desc,
+                    gboolean     push_undo)
+{
+  g_return_if_fail (GIMP_IS_CHANNEL (channel));
+
+  if (! gimp_item_is_attached (GIMP_ITEM (channel)))
+    push_undo = FALSE;
+
+  GIMP_CHANNEL_GET_CLASS (channel)->clear (channel, undo_desc, push_undo);
+}
+
+void
+gimp_channel_all (GimpChannel *channel,
+                  gboolean     push_undo)
+{
+  g_return_if_fail (GIMP_IS_CHANNEL (channel));
+
+  if (! gimp_item_is_attached (GIMP_ITEM (channel)))
+    push_undo = FALSE;
+
+  GIMP_CHANNEL_GET_CLASS (channel)->all (channel, push_undo);
+}
+
+void
+gimp_channel_invert (GimpChannel *channel,
+                     gboolean     push_undo)
+{
+  g_return_if_fail (GIMP_IS_CHANNEL (channel));
+
+  if (! gimp_item_is_attached (GIMP_ITEM (channel)))
+    push_undo = FALSE;
+
+  GIMP_CHANNEL_GET_CLASS (channel)->invert (channel, push_undo);
+}
+
+void
+gimp_channel_border (GimpChannel            *channel,
+                     gint                    radius_x,
+                     gint                    radius_y,
+                     GimpChannelBorderStyle  style,
+                     gboolean                edge_lock,
+                     gboolean                push_undo)
+{
+  g_return_if_fail (GIMP_IS_CHANNEL (channel));
+
+  if (! gimp_item_is_attached (GIMP_ITEM (channel)))
+    push_undo = FALSE;
+
+  GIMP_CHANNEL_GET_CLASS (channel)->border (channel,
+                                            radius_x, radius_y, style, edge_lock,
+                                            push_undo);
+}
+
+void
+gimp_channel_grow (GimpChannel *channel,
+                   gint         radius_x,
+                   gint         radius_y,
+                   gboolean     push_undo)
+{
+  g_return_if_fail (GIMP_IS_CHANNEL (channel));
+
+  if (! gimp_item_is_attached (GIMP_ITEM (channel)))
+    push_undo = FALSE;
+
+  GIMP_CHANNEL_GET_CLASS (channel)->grow (channel, radius_x, radius_y,
+                                          push_undo);
+}
+
+void
+gimp_channel_shrink (GimpChannel  *channel,
+                     gint          radius_x,
+                     gint          radius_y,
+                     gboolean      edge_lock,
+                     gboolean      push_undo)
+{
+  g_return_if_fail (GIMP_IS_CHANNEL (channel));
+
+  if (! gimp_item_is_attached (GIMP_ITEM (channel)))
+    push_undo = FALSE;
+
+  GIMP_CHANNEL_GET_CLASS (channel)->shrink (channel, radius_x, radius_y,
+                                            edge_lock, push_undo);
+}
+
+void
+gimp_channel_flood (GimpChannel *channel,
+                    gboolean     push_undo)
+{
+  g_return_if_fail (GIMP_IS_CHANNEL (channel));
+
+  if (! gimp_item_is_attached (GIMP_ITEM (channel)))
+    push_undo = FALSE;
+
+  GIMP_CHANNEL_GET_CLASS (channel)->flood (channel, push_undo);
+}
diff --git a/app/core/gimpchannel.h b/app/core/gimpchannel.h
new file mode 100644
index 0000000..348f4f6
--- /dev/null
+++ b/app/core/gimpchannel.h
@@ -0,0 +1,216 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_CHANNEL_H__
+#define __GIMP_CHANNEL_H__
+
+#include "gimpdrawable.h"
+
+
+#define GIMP_TYPE_CHANNEL            (gimp_channel_get_type ())
+#define GIMP_CHANNEL(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_CHANNEL, GimpChannel))
+#define GIMP_CHANNEL_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_CHANNEL, GimpChannelClass))
+#define GIMP_IS_CHANNEL(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_CHANNEL))
+#define GIMP_IS_CHANNEL_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_CHANNEL))
+#define GIMP_CHANNEL_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_CHANNEL, GimpChannelClass))
+
+
+typedef struct _GimpChannelClass GimpChannelClass;
+
+struct _GimpChannel
+{
+  GimpDrawable  parent_instance;
+
+  GimpRGB       color;             /*  Also stores the opacity        */
+  gboolean      show_masked;       /*  Show masked areas--as          */
+                                   /*  opposed to selected areas      */
+
+  GeglNode     *color_node;
+  GeglNode     *invert_node;
+  GeglNode     *mask_node;
+
+  /*  Selection mask variables  */
+  gboolean      boundary_known;    /*  is the current boundary valid  */
+  GimpBoundSeg *segs_in;           /*  outline of selected region     */
+  GimpBoundSeg *segs_out;          /*  outline of selected region     */
+  gint          num_segs_in;       /*  number of lines in boundary    */
+  gint          num_segs_out;      /*  number of lines in boundary    */
+  gboolean      empty;             /*  is the region empty?           */
+  gboolean      bounds_known;      /*  recalculate the bounds?        */
+  gint          x1, y1;            /*  coordinates for bounding box   */
+  gint          x2, y2;            /*  lower right hand coordinate    */
+};
+
+struct _GimpChannelClass
+{
+  GimpDrawableClass  parent_class;
+
+  /*  signals  */
+  void     (* color_changed) (GimpChannel             *channel);
+
+  /*  virtual functions  */
+  gboolean (* boundary)      (GimpChannel             *channel,
+                              const GimpBoundSeg     **segs_in,
+                              const GimpBoundSeg     **segs_out,
+                              gint                    *num_segs_in,
+                              gint                    *num_segs_out,
+                              gint                     x1,
+                              gint                     y1,
+                              gint                     x2,
+                              gint                     y2);
+  gboolean (* is_empty)      (GimpChannel             *channel);
+
+  void     (* feather)       (GimpChannel             *channel,
+                              gdouble                  radius_x,
+                              gdouble                  radius_y,
+                              gboolean                 edge_lock,
+                              gboolean                 push_undo);
+  void     (* sharpen)       (GimpChannel             *channel,
+                              gboolean                 push_undo);
+  void     (* clear)         (GimpChannel             *channel,
+                              const gchar             *undo_desc,
+                              gboolean                 push_undo);
+  void     (* all)           (GimpChannel             *channel,
+                              gboolean                 push_undo);
+  void     (* invert)        (GimpChannel             *channel,
+                              gboolean                 push_undo);
+  void     (* border)        (GimpChannel             *channel,
+                              gint                     radius_x,
+                              gint                     radius_y,
+                              GimpChannelBorderStyle   style,
+                              gboolean                 edge_lock,
+                              gboolean                 push_undo);
+  void     (* grow)          (GimpChannel             *channel,
+                              gint                     radius_x,
+                              gint                     radius_y,
+                              gboolean                 push_undo);
+  void     (* shrink)        (GimpChannel             *channel,
+                              gint                     radius_x,
+                              gint                     radius_y,
+                              gboolean                 edge_lock,
+                              gboolean                 push_undo);
+  void     (* flood)         (GimpChannel             *channel,
+                              gboolean                 push_undo);
+
+  const gchar *feather_desc;
+  const gchar *sharpen_desc;
+  const gchar *clear_desc;
+  const gchar *all_desc;
+  const gchar *invert_desc;
+  const gchar *border_desc;
+  const gchar *grow_desc;
+  const gchar *shrink_desc;
+  const gchar *flood_desc;
+};
+
+
+/*  function declarations  */
+
+GType         gimp_channel_get_type           (void) G_GNUC_CONST;
+
+GimpChannel * gimp_channel_new                (GimpImage         *image,
+                                               gint               width,
+                                               gint               height,
+                                               const gchar       *name,
+                                               const GimpRGB     *color);
+GimpChannel * gimp_channel_new_from_buffer    (GimpImage         *image,
+                                               GeglBuffer        *buffer,
+                                               const gchar       *name,
+                                               const GimpRGB     *color);
+GimpChannel * gimp_channel_new_from_alpha     (GimpImage         *image,
+                                               GimpDrawable      *drawable,
+                                               const gchar       *name,
+                                               const GimpRGB     *color);
+GimpChannel * gimp_channel_new_from_component (GimpImage         *image,
+                                               GimpChannelType    type,
+                                               const gchar       *name,
+                                               const GimpRGB     *color);
+
+GimpChannel * gimp_channel_get_parent         (GimpChannel       *channel);
+
+gdouble       gimp_channel_get_opacity        (GimpChannel       *channel);
+void          gimp_channel_set_opacity        (GimpChannel       *channel,
+                                               gdouble            opacity,
+                                               gboolean           push_undo);
+
+void          gimp_channel_get_color          (GimpChannel       *channel,
+                                               GimpRGB           *color);
+void          gimp_channel_set_color          (GimpChannel       *channel,
+                                               const GimpRGB     *color,
+                                               gboolean           push_undo);
+
+gboolean      gimp_channel_get_show_masked    (GimpChannel       *channel);
+void          gimp_channel_set_show_masked    (GimpChannel       *channel,
+                                               gboolean           show_masked);
+
+void          gimp_channel_push_undo          (GimpChannel       *mask,
+                                               const gchar       *undo_desc);
+
+
+/*  selection mask functions  */
+
+GimpChannel * gimp_channel_new_mask           (GimpImage              *image,
+                                               gint                    width,
+                                               gint                    height);
+
+gboolean      gimp_channel_boundary           (GimpChannel            *mask,
+                                               const GimpBoundSeg    **segs_in,
+                                               const GimpBoundSeg    **segs_out,
+                                               gint                   *num_segs_in,
+                                               gint                   *num_segs_out,
+                                               gint                    x1,
+                                               gint                    y1,
+                                               gint                    x2,
+                                               gint                    y2);
+gboolean      gimp_channel_is_empty           (GimpChannel            *mask);
+
+void          gimp_channel_feather            (GimpChannel            *mask,
+                                               gdouble                 radius_x,
+                                               gdouble                 radius_y,
+                                               gboolean                edge_lock,
+                                               gboolean                push_undo);
+void          gimp_channel_sharpen            (GimpChannel            *mask,
+                                               gboolean                push_undo);
+
+void          gimp_channel_clear              (GimpChannel            *mask,
+                                               const gchar            *undo_desc,
+                                               gboolean                push_undo);
+void          gimp_channel_all                (GimpChannel            *mask,
+                                               gboolean                push_undo);
+void          gimp_channel_invert             (GimpChannel            *mask,
+                                               gboolean                push_undo);
+
+void          gimp_channel_border             (GimpChannel            *mask,
+                                               gint                    radius_x,
+                                               gint                    radius_y,
+                                               GimpChannelBorderStyle  style,
+                                               gboolean                edge_lock,
+                                               gboolean                push_undo);
+void          gimp_channel_grow               (GimpChannel            *mask,
+                                               gint                    radius_x,
+                                               gint                    radius_y,
+                                               gboolean                push_undo);
+void          gimp_channel_shrink             (GimpChannel            *mask,
+                                               gint                    radius_x,
+                                               gint                    radius_y,
+                                               gboolean                edge_lock,
+                                               gboolean                push_undo);
+void          gimp_channel_flood              (GimpChannel            *mask,
+                                               gboolean                push_undo);
+
+
+#endif /* __GIMP_CHANNEL_H__ */
diff --git a/app/core/gimpchannelpropundo.c b/app/core/gimpchannelpropundo.c
new file mode 100644
index 0000000..f140d28
--- /dev/null
+++ b/app/core/gimpchannelpropundo.c
@@ -0,0 +1,108 @@
+/* Gimp - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+
+#include "core-types.h"
+
+#include "gimpimage.h"
+#include "gimpchannel.h"
+#include "gimpchannelpropundo.h"
+
+
+static void   gimp_channel_prop_undo_constructed (GObject             *object);
+
+static void   gimp_channel_prop_undo_pop         (GimpUndo            *undo,
+                                                  GimpUndoMode         undo_mode,
+                                                  GimpUndoAccumulator *accum);
+
+
+G_DEFINE_TYPE (GimpChannelPropUndo, gimp_channel_prop_undo, GIMP_TYPE_ITEM_UNDO)
+
+#define parent_class gimp_channel_prop_undo_parent_class
+
+
+static void
+gimp_channel_prop_undo_class_init (GimpChannelPropUndoClass *klass)
+{
+  GObjectClass  *object_class = G_OBJECT_CLASS (klass);
+  GimpUndoClass *undo_class   = GIMP_UNDO_CLASS (klass);
+
+  object_class->constructed = gimp_channel_prop_undo_constructed;
+
+  undo_class->pop           = gimp_channel_prop_undo_pop;
+}
+
+static void
+gimp_channel_prop_undo_init (GimpChannelPropUndo *undo)
+{
+}
+
+static void
+gimp_channel_prop_undo_constructed (GObject *object)
+{
+  GimpChannelPropUndo *channel_prop_undo = GIMP_CHANNEL_PROP_UNDO (object);
+  GimpChannel         *channel;
+
+  G_OBJECT_CLASS (parent_class)->constructed (object);
+
+  gimp_assert (GIMP_IS_CHANNEL (GIMP_ITEM_UNDO (object)->item));
+
+  channel = GIMP_CHANNEL (GIMP_ITEM_UNDO (object)->item);
+
+  switch (GIMP_UNDO (object)->undo_type)
+    {
+    case GIMP_UNDO_CHANNEL_COLOR:
+      gimp_channel_get_color (channel, &channel_prop_undo->color);
+      break;
+
+    default:
+      g_return_if_reached ();
+    }
+}
+
+static void
+gimp_channel_prop_undo_pop (GimpUndo            *undo,
+                            GimpUndoMode         undo_mode,
+                            GimpUndoAccumulator *accum)
+{
+  GimpChannelPropUndo *channel_prop_undo = GIMP_CHANNEL_PROP_UNDO (undo);
+  GimpChannel         *channel           = GIMP_CHANNEL (GIMP_ITEM_UNDO (undo)->item);
+
+  GIMP_UNDO_CLASS (parent_class)->pop (undo, undo_mode, accum);
+
+  switch (undo->undo_type)
+    {
+    case GIMP_UNDO_CHANNEL_COLOR:
+      {
+        GimpRGB color;
+
+        gimp_channel_get_color (channel, &color);
+        gimp_channel_set_color (channel, &channel_prop_undo->color, FALSE);
+        channel_prop_undo->color = color;
+      }
+      break;
+
+    default:
+      g_return_if_reached ();
+    }
+}
diff --git a/app/core/gimpchannelpropundo.h b/app/core/gimpchannelpropundo.h
new file mode 100644
index 0000000..2aa7ad5
--- /dev/null
+++ b/app/core/gimpchannelpropundo.h
@@ -0,0 +1,52 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_CHANNEL_PROP_UNDO_H__
+#define __GIMP_CHANNEL_PROP_UNDO_H__
+
+
+#include "gimpitemundo.h"
+
+
+#define GIMP_TYPE_CHANNEL_PROP_UNDO            (gimp_channel_prop_undo_get_type ())
+#define GIMP_CHANNEL_PROP_UNDO(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_CHANNEL_PROP_UNDO, GimpChannelPropUndo))
+#define GIMP_CHANNEL_PROP_UNDO_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_CHANNEL_PROP_UNDO, GimpChannelPropUndoClass))
+#define GIMP_IS_CHANNEL_PROP_UNDO(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_CHANNEL_PROP_UNDO))
+#define GIMP_IS_CHANNEL_PROP_UNDO_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_CHANNEL_PROP_UNDO))
+#define GIMP_CHANNEL_PROP_UNDO_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_CHANNEL_PROP_UNDO, GimpChannelPropUndoClass))
+
+
+typedef struct _GimpChannelPropUndo      GimpChannelPropUndo;
+typedef struct _GimpChannelPropUndoClass GimpChannelPropUndoClass;
+
+struct _GimpChannelPropUndo
+{
+  GimpItemUndo  parent_instance;
+
+  GimpRGB       color;
+};
+
+struct _GimpChannelPropUndoClass
+{
+  GimpItemUndoClass  parent_class;
+};
+
+
+GType   gimp_channel_prop_undo_get_type (void) G_GNUC_CONST;
+
+
+#endif /* __GIMP_CHANNEL_PROP_UNDO_H__ */
diff --git a/app/core/gimpchannelundo.c b/app/core/gimpchannelundo.c
new file mode 100644
index 0000000..1892ced
--- /dev/null
+++ b/app/core/gimpchannelundo.c
@@ -0,0 +1,214 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gimpimage.h"
+#include "gimpchannel.h"
+#include "gimpchannelundo.h"
+
+
+enum
+{
+  PROP_0,
+  PROP_PREV_PARENT,
+  PROP_PREV_POSITION,
+  PROP_PREV_CHANNEL
+};
+
+
+static void    gimp_channel_undo_constructed  (GObject             *object);
+static void    gimp_channel_undo_set_property (GObject             *object,
+                                               guint                property_id,
+                                               const GValue        *value,
+                                               GParamSpec          *pspec);
+static void    gimp_channel_undo_get_property (GObject             *object,
+                                               guint                property_id,
+                                               GValue              *value,
+                                               GParamSpec          *pspec);
+
+static gint64  gimp_channel_undo_get_memsize  (GimpObject          *object,
+                                               gint64              *gui_size);
+
+static void    gimp_channel_undo_pop          (GimpUndo            *undo,
+                                               GimpUndoMode         undo_mode,
+                                               GimpUndoAccumulator *accum);
+
+
+G_DEFINE_TYPE (GimpChannelUndo, gimp_channel_undo, GIMP_TYPE_ITEM_UNDO)
+
+#define parent_class gimp_channel_undo_parent_class
+
+
+static void
+gimp_channel_undo_class_init (GimpChannelUndoClass *klass)
+{
+  GObjectClass    *object_class      = G_OBJECT_CLASS (klass);
+  GimpObjectClass *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+  GimpUndoClass   *undo_class        = GIMP_UNDO_CLASS (klass);
+
+  object_class->constructed      = gimp_channel_undo_constructed;
+  object_class->set_property     = gimp_channel_undo_set_property;
+  object_class->get_property     = gimp_channel_undo_get_property;
+
+  gimp_object_class->get_memsize = gimp_channel_undo_get_memsize;
+
+  undo_class->pop                = gimp_channel_undo_pop;
+
+  g_object_class_install_property (object_class, PROP_PREV_PARENT,
+                                   g_param_spec_object ("prev-parent",
+                                                        NULL, NULL,
+                                                        GIMP_TYPE_CHANNEL,
+                                                        GIMP_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT_ONLY));
+
+  g_object_class_install_property (object_class, PROP_PREV_POSITION,
+                                   g_param_spec_int ("prev-position",
+                                                     NULL, NULL,
+                                                     0, G_MAXINT, 0,
+                                                     GIMP_PARAM_READWRITE |
+                                                     G_PARAM_CONSTRUCT_ONLY));
+
+  g_object_class_install_property (object_class, PROP_PREV_CHANNEL,
+                                   g_param_spec_object ("prev-channel",
+                                                        NULL, NULL,
+                                                        GIMP_TYPE_CHANNEL,
+                                                        GIMP_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT_ONLY));
+}
+
+static void
+gimp_channel_undo_init (GimpChannelUndo *undo)
+{
+}
+
+static void
+gimp_channel_undo_constructed (GObject *object)
+{
+  G_OBJECT_CLASS (parent_class)->constructed (object);
+
+  gimp_assert (GIMP_IS_CHANNEL (GIMP_ITEM_UNDO (object)->item));
+}
+
+static void
+gimp_channel_undo_set_property (GObject      *object,
+                                guint         property_id,
+                                const GValue *value,
+                                GParamSpec   *pspec)
+{
+  GimpChannelUndo *channel_undo = GIMP_CHANNEL_UNDO (object);
+
+  switch (property_id)
+    {
+    case PROP_PREV_PARENT:
+      channel_undo->prev_parent = g_value_get_object (value);
+      break;
+    case PROP_PREV_POSITION:
+      channel_undo->prev_position = g_value_get_int (value);
+      break;
+    case PROP_PREV_CHANNEL:
+      channel_undo->prev_channel = g_value_get_object (value);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_channel_undo_get_property (GObject    *object,
+                                guint       property_id,
+                                GValue     *value,
+                                GParamSpec *pspec)
+{
+  GimpChannelUndo *channel_undo = GIMP_CHANNEL_UNDO (object);
+
+  switch (property_id)
+    {
+    case PROP_PREV_PARENT:
+      g_value_set_object (value, channel_undo->prev_parent);
+      break;
+    case PROP_PREV_POSITION:
+      g_value_set_int (value, channel_undo->prev_position);
+      break;
+    case PROP_PREV_CHANNEL:
+      g_value_set_object (value, channel_undo->prev_channel);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static gint64
+gimp_channel_undo_get_memsize (GimpObject *object,
+                               gint64     *gui_size)
+{
+  GimpItemUndo *item_undo = GIMP_ITEM_UNDO (object);
+  gint64        memsize   = 0;
+
+  if (! gimp_item_is_attached (item_undo->item))
+    memsize += gimp_object_get_memsize (GIMP_OBJECT (item_undo->item),
+                                        gui_size);
+
+  return memsize + GIMP_OBJECT_CLASS (parent_class)->get_memsize (object,
+                                                                  gui_size);
+}
+
+static void
+gimp_channel_undo_pop (GimpUndo            *undo,
+                       GimpUndoMode         undo_mode,
+                       GimpUndoAccumulator *accum)
+{
+  GimpChannelUndo *channel_undo = GIMP_CHANNEL_UNDO (undo);
+  GimpChannel     *channel      = GIMP_CHANNEL (GIMP_ITEM_UNDO (undo)->item);
+
+  GIMP_UNDO_CLASS (parent_class)->pop (undo, undo_mode, accum);
+
+  if ((undo_mode       == GIMP_UNDO_MODE_UNDO &&
+       undo->undo_type == GIMP_UNDO_CHANNEL_ADD) ||
+      (undo_mode       == GIMP_UNDO_MODE_REDO &&
+       undo->undo_type == GIMP_UNDO_CHANNEL_REMOVE))
+    {
+      /*  remove channel  */
+
+      /*  record the current parent and position  */
+      channel_undo->prev_parent   = gimp_channel_get_parent (channel);
+      channel_undo->prev_position = gimp_item_get_index (GIMP_ITEM (channel));
+
+      gimp_image_remove_channel (undo->image, channel, FALSE,
+                                 channel_undo->prev_channel);
+    }
+  else
+    {
+      /*  restore channel  */
+
+      /*  record the active channel  */
+      channel_undo->prev_channel = gimp_image_get_active_channel (undo->image);
+
+      gimp_image_add_channel (undo->image, channel,
+                              channel_undo->prev_parent,
+                              channel_undo->prev_position, FALSE);
+    }
+}
diff --git a/app/core/gimpchannelundo.h b/app/core/gimpchannelundo.h
new file mode 100644
index 0000000..7bfceb9
--- /dev/null
+++ b/app/core/gimpchannelundo.h
@@ -0,0 +1,54 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_CHANNEL_UNDO_H__
+#define __GIMP_CHANNEL_UNDO_H__
+
+
+#include "gimpitemundo.h"
+
+
+#define GIMP_TYPE_CHANNEL_UNDO            (gimp_channel_undo_get_type ())
+#define GIMP_CHANNEL_UNDO(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_CHANNEL_UNDO, GimpChannelUndo))
+#define GIMP_CHANNEL_UNDO_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_CHANNEL_UNDO, GimpChannelUndoClass))
+#define GIMP_IS_CHANNEL_UNDO(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_CHANNEL_UNDO))
+#define GIMP_IS_CHANNEL_UNDO_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_CHANNEL_UNDO))
+#define GIMP_CHANNEL_UNDO_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_CHANNEL_UNDO, GimpChannelUndoClass))
+
+
+typedef struct _GimpChannelUndo      GimpChannelUndo;
+typedef struct _GimpChannelUndoClass GimpChannelUndoClass;
+
+struct _GimpChannelUndo
+{
+  GimpItemUndo  parent_instance;
+
+  GimpChannel  *prev_parent;
+  gint          prev_position;   /*  former position in list  */
+  GimpChannel  *prev_channel;    /*  previous active channel  */
+};
+
+struct _GimpChannelUndoClass
+{
+  GimpItemUndoClass  parent_class;
+};
+
+
+GType   gimp_channel_undo_get_type (void) G_GNUC_CONST;
+
+
+#endif /* __GIMP_CHANNEL_UNDO_H__ */
diff --git a/app/core/gimpchunkiterator.c b/app/core/gimpchunkiterator.c
new file mode 100644
index 0000000..616bb46
--- /dev/null
+++ b/app/core/gimpchunkiterator.c
@@ -0,0 +1,555 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1999 Spencer Kimball and Peter Mattis
+ *
+ * gimpchunkiterator.c
+ * Copyright (C) 2019 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+
+#include "config.h"
+
+#include <stdlib.h>
+
+#include <cairo.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpmath/gimpmath.h"
+
+#include "core-types.h"
+
+#include "gimpchunkiterator.h"
+
+
+/* the maximal chunk size */
+#define MAX_CHUNK_WIDTH          4096
+#define MAX_CHUNK_HEIGHT         4096
+
+/* the default iteration interval */
+#define DEFAULT_INTERVAL         (1.0 / 15.0) /* seconds */
+
+/* the minimal area to process per iteration */
+#define MIN_AREA_PER_ITERATION   4096
+
+/* the maximal ratio between the actual processed area and the target area,
+ * above which the current chunk height is readjusted, even in the middle of a
+ * row, to better match the target area
+ */
+#define MAX_AREA_RATIO           2.0
+
+/* the width of the target-area sliding window */
+#define TARGET_AREA_HISTORY_SIZE 3
+
+
+struct _GimpChunkIterator
+{
+  cairo_region_t *region;
+  cairo_region_t *priority_region;
+
+  GeglRectangle   tile_rect;
+  GeglRectangle   priority_rect;
+
+  gdouble         interval;
+
+  cairo_region_t *current_region;
+  GeglRectangle   current_rect;
+
+  gint            current_x;
+  gint            current_y;
+  gint            current_height;
+
+  gint64          iteration_time;
+
+  gint64          last_time;
+  gint            last_area;
+
+  gdouble         target_area;
+  gdouble         target_area_min;
+  gdouble         target_area_history[TARGET_AREA_HISTORY_SIZE];
+  gint            target_area_history_i;
+  gint            target_area_history_n;
+};
+
+
+/*  local function prototypes  */
+
+static void       gimp_chunk_iterator_set_current_rect   (GimpChunkIterator   *iter,
+                                                          const GeglRectangle *rect);
+static void       gimp_chunk_iterator_merge_current_rect (GimpChunkIterator   *iter);
+
+static void       gimp_chunk_iterator_merge              (GimpChunkIterator   *iter);
+
+static gboolean   gimp_chunk_iterator_prepare            (GimpChunkIterator   *iter);
+
+static void       gimp_chunk_iterator_set_target_area    (GimpChunkIterator   *iter,
+                                                          gdouble              target_area);
+static gdouble    gimp_chunk_iterator_get_target_area    (GimpChunkIterator   *iter);
+static void       gimp_chunk_iterator_reset_target_area  (GimpChunkIterator   *iter);
+
+static void       gimp_chunk_iterator_calc_rect          (GimpChunkIterator   *iter,
+                                                          GeglRectangle       *rect,
+                                                          gboolean             readjust_height);
+
+
+/*  private functions  */
+
+static void
+gimp_chunk_iterator_set_current_rect (GimpChunkIterator   *iter,
+                                      const GeglRectangle *rect)
+{
+  cairo_region_subtract_rectangle (iter->current_region,
+                                   (const cairo_rectangle_int_t *) rect);
+
+  iter->current_rect   = *rect;
+
+  iter->current_x      = rect->x;
+  iter->current_y      = rect->y;
+  iter->current_height = 0;
+}
+
+static void
+gimp_chunk_iterator_merge_current_rect (GimpChunkIterator *iter)
+{
+  GeglRectangle rect;
+
+  if (gegl_rectangle_is_empty (&iter->current_rect))
+    return;
+
+  /* merge the remainder of the current row */
+  rect.x      = iter->current_x;
+  rect.y      = iter->current_y;
+  rect.width  = iter->current_rect.x + iter->current_rect.width -
+                iter->current_x;
+  rect.height = iter->current_height;
+
+  cairo_region_union_rectangle (iter->current_region,
+                                (const cairo_rectangle_int_t *) &rect);
+
+  /* merge the remainder of the current rect */
+  rect.x      = iter->current_rect.x;
+  rect.y      = iter->current_y + iter->current_height;
+  rect.width  = iter->current_rect.width;
+  rect.height = iter->current_rect.y + iter->current_rect.height - rect.y;
+
+  cairo_region_union_rectangle (iter->current_region,
+                                (const cairo_rectangle_int_t *) &rect);
+
+  /* reset the current rect and coordinates */
+  iter->current_rect.x      = 0;
+  iter->current_rect.y      = 0;
+  iter->current_rect.width  = 0;
+  iter->current_rect.height = 0;
+
+  iter->current_x           = 0;
+  iter->current_y           = 0;
+  iter->current_height      = 0;
+}
+
+static void
+gimp_chunk_iterator_merge (GimpChunkIterator *iter)
+{
+  /* merge the current rect back to the current region */
+  gimp_chunk_iterator_merge_current_rect (iter);
+
+  /* merge the priority region back to the global region */
+  if (iter->priority_region)
+    {
+      cairo_region_union (iter->region, iter->priority_region);
+
+      g_clear_pointer (&iter->priority_region, cairo_region_destroy);
+
+      iter->current_region = iter->region;
+    }
+}
+
+static gboolean
+gimp_chunk_iterator_prepare (GimpChunkIterator *iter)
+{
+  if (iter->current_x == iter->current_rect.x + iter->current_rect.width)
+    {
+      iter->current_x       = iter->current_rect.x;
+      iter->current_y      += iter->current_height;
+      iter->current_height  = 0;
+
+      if (iter->current_y == iter->current_rect.y + iter->current_rect.height)
+        {
+          GeglRectangle rect;
+
+          if (! iter->priority_region &&
+              ! gegl_rectangle_is_empty (&iter->priority_rect))
+            {
+              iter->priority_region = cairo_region_copy (iter->region);
+
+              cairo_region_intersect_rectangle (
+                iter->priority_region,
+                (const cairo_rectangle_int_t *) &iter->priority_rect);
+
+              cairo_region_subtract_rectangle (
+                iter->region,
+                (const cairo_rectangle_int_t *) &iter->priority_rect);
+            }
+
+          if (! iter->priority_region ||
+              cairo_region_is_empty (iter->priority_region))
+            {
+              iter->current_region = iter->region;
+            }
+          else
+            {
+              iter->current_region = iter->priority_region;
+            }
+
+          if (cairo_region_is_empty (iter->current_region))
+            {
+              iter->current_rect.x      = 0;
+              iter->current_rect.y      = 0;
+              iter->current_rect.width  = 0;
+              iter->current_rect.height = 0;
+
+              iter->current_x           = 0;
+              iter->current_y           = 0;
+              iter->current_height      = 0;
+
+              return FALSE;
+            }
+
+          cairo_region_get_rectangle (iter->current_region, 0,
+                                      (cairo_rectangle_int_t *) &rect);
+
+          gimp_chunk_iterator_set_current_rect (iter, &rect);
+        }
+    }
+
+  return TRUE;
+}
+
+static gint
+compare_double (const gdouble *x,
+                const gdouble *y)
+{
+  return (*x > *y) - (*x < *y);
+}
+
+static void
+gimp_chunk_iterator_set_target_area (GimpChunkIterator *iter,
+                                     gdouble            target_area)
+{
+  gdouble target_area_history[TARGET_AREA_HISTORY_SIZE];
+
+  iter->target_area_min = MIN (iter->target_area_min, target_area);
+
+  iter->target_area_history[iter->target_area_history_i++] = target_area;
+
+  iter->target_area_history_n  = MAX (iter->target_area_history_n,
+                                      iter->target_area_history_i);
+  iter->target_area_history_i %= TARGET_AREA_HISTORY_SIZE;
+
+  memcpy (target_area_history, iter->target_area_history,
+          iter->target_area_history_n * sizeof (gdouble));
+
+  qsort (target_area_history, iter->target_area_history_n, sizeof (gdouble),
+         (gpointer) compare_double);
+
+  iter->target_area = target_area_history[iter->target_area_history_n / 2];
+}
+
+static gdouble
+gimp_chunk_iterator_get_target_area (GimpChunkIterator *iter)
+{
+  if (iter->target_area)
+    return iter->target_area;
+  else
+    return iter->tile_rect.width * iter->tile_rect.height;
+}
+
+static void
+gimp_chunk_iterator_reset_target_area (GimpChunkIterator *iter)
+{
+  if (iter->target_area_history_n)
+    {
+      iter->target_area           = iter->target_area_min;
+      iter->target_area_min       = MAX_CHUNK_WIDTH * MAX_CHUNK_HEIGHT;
+      iter->target_area_history_i = 0;
+      iter->target_area_history_n = 0;
+    }
+}
+
+static void
+gimp_chunk_iterator_calc_rect (GimpChunkIterator *iter,
+                               GeglRectangle     *rect,
+                               gboolean           readjust_height)
+{
+  gdouble target_area;
+  gdouble aspect_ratio;
+  gint    offset_x;
+  gint    offset_y;
+
+  if (readjust_height)
+    gimp_chunk_iterator_reset_target_area (iter);
+
+  target_area = gimp_chunk_iterator_get_target_area (iter);
+
+  aspect_ratio = (gdouble) iter->tile_rect.height /
+                 (gdouble) iter->tile_rect.width;
+
+  rect->x = iter->current_x;
+  rect->y = iter->current_y;
+
+  offset_x = rect->x - iter->tile_rect.x;
+  offset_y = rect->y - iter->tile_rect.y;
+
+  if (readjust_height)
+    {
+      rect->height = RINT ((offset_y + sqrt (target_area * aspect_ratio)) /
+                           iter->tile_rect.height)                        *
+                     iter->tile_rect.height                               -
+                     offset_y;
+
+      if (rect->height <= 0)
+        rect->height += iter->tile_rect.height;
+
+      rect->height = MIN (rect->height,
+                          iter->current_rect.y + iter->current_rect.height -
+                          rect->y);
+      rect->height = MIN (rect->height, MAX_CHUNK_HEIGHT);
+    }
+  else
+    {
+      rect->height = iter->current_height;
+    }
+
+  rect->width = RINT ((offset_x + (gdouble) target_area   /
+                                  (gdouble) rect->height) /
+                      iter->tile_rect.width)              *
+                iter->tile_rect.width                     -
+                offset_x;
+
+  if (rect->width <= 0)
+    rect->width += iter->tile_rect.width;
+
+  rect->width = MIN (rect->width,
+                     iter->current_rect.x + iter->current_rect.width -
+                     rect->x);
+  rect->width = MIN (rect->width, MAX_CHUNK_WIDTH);
+}
+
+
+/*  public functions  */
+
+GimpChunkIterator *
+gimp_chunk_iterator_new (cairo_region_t *region)
+{
+  GimpChunkIterator *iter;
+
+  g_return_val_if_fail (region != NULL, NULL);
+
+  iter = g_slice_new0 (GimpChunkIterator);
+
+  iter->region         = region;
+  iter->current_region = region;
+
+  g_object_get (gegl_config (),
+                "tile-width",  &iter->tile_rect.width,
+                "tile-height", &iter->tile_rect.height,
+                NULL);
+
+  iter->interval = DEFAULT_INTERVAL;
+
+  return iter;
+}
+
+void
+gimp_chunk_iterator_set_tile_rect (GimpChunkIterator   *iter,
+                                   const GeglRectangle *rect)
+{
+  g_return_if_fail (iter != NULL);
+  g_return_if_fail (rect != NULL);
+  g_return_if_fail (! gegl_rectangle_is_empty (rect));
+
+  iter->tile_rect = *rect;
+}
+
+void
+gimp_chunk_iterator_set_priority_rect (GimpChunkIterator   *iter,
+                                       const GeglRectangle *rect)
+{
+  const GeglRectangle empty_rect = {};
+
+  g_return_if_fail (iter != NULL);
+
+  if (! rect)
+    rect = &empty_rect;
+
+  if (! gegl_rectangle_equal (rect, &iter->priority_rect))
+    {
+      iter->priority_rect = *rect;
+
+      gimp_chunk_iterator_merge (iter);
+    }
+}
+
+void
+gimp_chunk_iterator_set_interval (GimpChunkIterator *iter,
+                                  gdouble            interval)
+{
+  g_return_if_fail (iter != NULL);
+
+  interval = MAX (interval, 0.0);
+
+  if (interval != iter->interval)
+    {
+      if (iter->interval)
+        {
+          gdouble ratio = interval / iter->interval;
+          gint    i;
+
+          iter->target_area *= ratio;
+
+          for (i = 0; i < TARGET_AREA_HISTORY_SIZE; i++)
+            iter->target_area_history[i] *= ratio;
+        }
+
+      iter->interval = interval;
+    }
+}
+
+gboolean
+gimp_chunk_iterator_next (GimpChunkIterator *iter)
+{
+  g_return_val_if_fail (iter != NULL, FALSE);
+
+  if (! gimp_chunk_iterator_prepare (iter))
+    {
+      gimp_chunk_iterator_stop (iter, TRUE);
+
+      return FALSE;
+    }
+
+  iter->iteration_time = g_get_monotonic_time ();
+
+  iter->last_time = iter->iteration_time;
+  iter->last_area = 0;
+
+  return TRUE;
+}
+
+gboolean
+gimp_chunk_iterator_get_rect (GimpChunkIterator *iter,
+                              GeglRectangle     *rect)
+{
+  gint64 time;
+
+  g_return_val_if_fail (iter != NULL, FALSE);
+  g_return_val_if_fail (rect != NULL, FALSE);
+
+  if (! gimp_chunk_iterator_prepare (iter))
+    return FALSE;
+
+  time = g_get_monotonic_time ();
+
+  if (iter->last_area >= MIN_AREA_PER_ITERATION)
+    {
+      gdouble interval;
+
+      interval = (gdouble) (time - iter->last_time) / G_TIME_SPAN_SECOND;
+
+      gimp_chunk_iterator_set_target_area (
+        iter,
+        iter->last_area * iter->interval / interval);
+
+      interval = (gdouble) (time - iter->iteration_time) / G_TIME_SPAN_SECOND;
+
+      if (interval > iter->interval)
+        return FALSE;
+    }
+
+  if (iter->current_x == iter->current_rect.x)
+    {
+      gimp_chunk_iterator_calc_rect (iter, rect, TRUE);
+    }
+  else
+    {
+      gimp_chunk_iterator_calc_rect (iter, rect, FALSE);
+
+      if (rect->width * rect->height >=
+          MAX_AREA_RATIO * gimp_chunk_iterator_get_target_area (iter))
+        {
+          GeglRectangle old_rect = *rect;
+
+          gimp_chunk_iterator_calc_rect (iter, rect, TRUE);
+
+          if (rect->height >= old_rect.height)
+            *rect = old_rect;
+        }
+    }
+
+  if (rect->height != iter->current_height)
+    {
+      /* if the chunk height changed in the middle of a row, merge the
+       * remaining area back into the current region, and reset the current
+       * area to the remainder of the row, using the new chunk height
+       */
+      if (rect->x != iter->current_rect.x)
+        {
+          GeglRectangle rem;
+
+          rem.x      = rect->x;
+          rem.y      = rect->y;
+          rem.width  = iter->current_rect.x + iter->current_rect.width -
+                       rect->x;
+          rem.height = rect->height;
+
+          gimp_chunk_iterator_merge_current_rect (iter);
+
+          gimp_chunk_iterator_set_current_rect (iter, &rem);
+        }
+
+      iter->current_height = rect->height;
+    }
+
+  iter->current_x += rect->width;
+
+  iter->last_time = time;
+  iter->last_area = rect->width * rect->height;
+
+  return TRUE;
+}
+
+cairo_region_t *
+gimp_chunk_iterator_stop (GimpChunkIterator *iter,
+                          gboolean           free_region)
+{
+  cairo_region_t *result = NULL;
+
+  g_return_val_if_fail (iter != NULL, NULL);
+
+  if (free_region)
+    {
+      cairo_region_destroy (iter->region);
+    }
+  else
+    {
+      gimp_chunk_iterator_merge (iter);
+
+      result = iter->region;
+    }
+
+  g_clear_pointer (&iter->priority_region, cairo_region_destroy);
+
+  g_slice_free (GimpChunkIterator, iter);
+
+  return result;
+}
diff --git a/app/core/gimpchunkiterator.h b/app/core/gimpchunkiterator.h
new file mode 100644
index 0000000..e1756f3
--- /dev/null
+++ b/app/core/gimpchunkiterator.h
@@ -0,0 +1,44 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpchunkiterator.h
+ * Copyright (C) 2019 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_CHUNK_ITEARTOR_H__
+#define __GIMP_CHUNK_ITEARTOR_H__
+
+
+GimpChunkIterator * gimp_chunk_iterator_new               (cairo_region_t      *region);
+
+void                gimp_chunk_iterator_set_tile_rect     (GimpChunkIterator   *iter,
+                                                           const GeglRectangle *rect);
+
+void                gimp_chunk_iterator_set_priority_rect (GimpChunkIterator   *iter,
+                                                           const GeglRectangle *rect);
+
+void                gimp_chunk_iterator_set_interval      (GimpChunkIterator   *iter,
+                                                           gdouble              interval);
+
+gboolean            gimp_chunk_iterator_next              (GimpChunkIterator   *iter);
+gboolean            gimp_chunk_iterator_get_rect          (GimpChunkIterator   *iter,
+                                                           GeglRectangle       *rect);
+
+cairo_region_t    * gimp_chunk_iterator_stop              (GimpChunkIterator   *iter,
+                                                           gboolean             free_region);
+
+
+#endif  /*  __GIMP_CHUNK_ITEARTOR_H__  */
diff --git a/app/core/gimpcontainer-filter.c b/app/core/gimpcontainer-filter.c
new file mode 100644
index 0000000..956a4a0
--- /dev/null
+++ b/app/core/gimpcontainer-filter.c
@@ -0,0 +1,174 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1997 Spencer Kimball and Peter Mattis
+ *
+ * gimpcontainer-filter.c
+ * Copyright (C) 2003  Sven Neumann <sven@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <glib-object.h>
+
+#include "core-types.h"
+
+#include "gimpcontainer.h"
+#include "gimpcontainer-filter.h"
+#include "gimplist.h"
+
+
+typedef struct
+{
+  GimpObjectFilterFunc   filter;
+  GimpContainer         *container;
+  gpointer               user_data;
+} GimpContainerFilterContext;
+
+
+static void
+gimp_container_filter_foreach_func (GimpObject                 *object,
+                                    GimpContainerFilterContext *context)
+{
+  if (context->filter (object, context->user_data))
+    gimp_container_add (context->container, object);
+}
+
+/**
+ * gimp_container_filter:
+ * @container: a #GimpContainer to filter
+ * @filter: a #GimpObjectFilterFunc
+ * @user_data: a pointer passed to @filter
+ *
+ * Calls the supplied @filter function on each object in @container.
+ * A return value of %TRUE is interpreted as a match.
+ *
+ * Returns: a weak #GimpContainer filled with matching objects.
+ **/
+GimpContainer *
+gimp_container_filter (GimpContainer        *container,
+                       GimpObjectFilterFunc  filter,
+                       gpointer              user_data)
+{
+  GimpContainer              *result;
+  GimpContainerFilterContext  context;
+
+  g_return_val_if_fail (GIMP_IS_CONTAINER (container), NULL);
+  g_return_val_if_fail (filter != NULL, NULL);
+
+  result =
+    g_object_new (G_TYPE_FROM_INSTANCE (container),
+                  "children-type", gimp_container_get_children_type (container),
+                  "policy",        GIMP_CONTAINER_POLICY_WEAK,
+                  NULL);
+
+  context.filter    = filter;
+  context.container = result;
+  context.user_data = user_data;
+
+  gimp_container_foreach (container,
+                          (GFunc) gimp_container_filter_foreach_func,
+                          &context);
+
+  /*  This is somewhat ugly, but it keeps lists in the same order.  */
+  if (GIMP_IS_LIST (result))
+    gimp_list_reverse (GIMP_LIST (result));
+
+
+  return result;
+}
+
+
+static gboolean
+gimp_object_filter_by_name (GimpObject   *object,
+                            const GRegex *regex)
+{
+  return g_regex_match (regex, gimp_object_get_name (object), 0, NULL);
+}
+
+/**
+ * gimp_container_filter_by_name:
+ * @container: a #GimpContainer to filter
+ * @regexp: a regular expression (as a %NULL-terminated string)
+ * @error: error location to report errors or %NULL
+ *
+ * This function performs a case-insensitive regular expression search
+ * on the names of the GimpObjects in @container.
+ *
+ * Returns: a weak #GimpContainer filled with matching objects.
+ **/
+GimpContainer *
+gimp_container_filter_by_name (GimpContainer  *container,
+                               const gchar    *regexp,
+                               GError        **error)
+{
+  GimpContainer *result;
+  GRegex        *regex;
+
+  g_return_val_if_fail (GIMP_IS_CONTAINER (container), NULL);
+  g_return_val_if_fail (regexp != NULL, NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, NULL);
+
+  regex = g_regex_new (regexp, G_REGEX_CASELESS | G_REGEX_OPTIMIZE, 0,
+                       error);
+
+  if (! regex)
+    return NULL;
+
+  result =
+    gimp_container_filter (container,
+                           (GimpObjectFilterFunc) gimp_object_filter_by_name,
+                           regex);
+
+  g_regex_unref (regex);
+
+  return result;
+}
+
+
+gchar **
+gimp_container_get_filtered_name_array (GimpContainer *container,
+                                        const gchar   *regexp,
+                                        gint          *length)
+{
+  GimpContainer *weak;
+  GError        *error = NULL;
+
+  g_return_val_if_fail (GIMP_IS_CONTAINER (container), NULL);
+  g_return_val_if_fail (length != NULL, NULL);
+
+  if (regexp == NULL || strlen (regexp) == 0)
+    return (gimp_container_get_name_array (container, length));
+
+  weak = gimp_container_filter_by_name (container, regexp, &error);
+
+  if (weak)
+    {
+      gchar **retval = gimp_container_get_name_array (weak, length);
+
+      g_object_unref (weak);
+
+      return retval;
+    }
+  else
+    {
+      g_warning ("%s", error->message);
+      g_error_free (error);
+
+      *length = 0;
+      return NULL;
+    }
+}
diff --git a/app/core/gimpcontainer-filter.h b/app/core/gimpcontainer-filter.h
new file mode 100644
index 0000000..7c98b32
--- /dev/null
+++ b/app/core/gimpcontainer-filter.h
@@ -0,0 +1,38 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1997 Spencer Kimball and Peter Mattis
+ *
+ * gimpcontainer-filter.c
+ * Copyright (C) 2003  Sven Neumann <sven@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_CONTAINER_FILTER_H__
+#define __GIMP_CONTAINER_FILTER_H__
+
+
+GimpContainer * gimp_container_filter         (GimpContainer        *container,
+                                               GimpObjectFilterFunc  filter,
+                                               gpointer              user_data);
+GimpContainer * gimp_container_filter_by_name (GimpContainer        *container,
+                                               const gchar          *regexp,
+                                               GError              **error);
+
+gchar        ** gimp_container_get_filtered_name_array
+                                              (GimpContainer        *container,
+                                               const gchar          *regexp,
+                                               gint                 *length);
+
+
+#endif  /* __GIMP_CONTAINER_FILTER_H__ */
diff --git a/app/core/gimpcontainer.c b/app/core/gimpcontainer.c
new file mode 100644
index 0000000..322a3ec
--- /dev/null
+++ b/app/core/gimpcontainer.c
@@ -0,0 +1,1167 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1997 Spencer Kimball and Peter Mattis
+ *
+ * gimpcontainer.c
+ * Copyright (C) 2001 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gio/gio.h>
+#include <gegl.h>
+
+#include "libgimpconfig/gimpconfig.h"
+
+#include "core-types.h"
+
+#include "gimp.h"
+#include "gimp-memsize.h"
+#include "gimpcontainer.h"
+#include "gimpmarshal.h"
+
+
+/* #define DEBUG_CONTAINER */
+
+#ifdef DEBUG_CONTAINER
+#define D(stmnt) stmnt
+#else
+#define D(stmnt)
+#endif
+
+
+enum
+{
+  ADD,
+  REMOVE,
+  REORDER,
+  FREEZE,
+  THAW,
+  LAST_SIGNAL
+};
+
+enum
+{
+  PROP_0,
+  PROP_CHILDREN_TYPE,
+  PROP_POLICY
+};
+
+
+typedef struct
+{
+  gchar     *signame;
+  GCallback  callback;
+  gpointer   callback_data;
+
+  GQuark     quark;  /*  used to attach the signal id's of child signals  */
+} GimpContainerHandler;
+
+struct _GimpContainerPrivate
+{
+  GType                children_type;
+  GimpContainerPolicy  policy;
+  gint                 n_children;
+
+  GList               *handlers;
+  gint                 freeze_count;
+};
+
+
+/*  local function prototypes  */
+
+static void   gimp_container_config_iface_init   (GimpConfigInterface *iface);
+
+static void       gimp_container_dispose         (GObject          *object);
+
+static void       gimp_container_set_property    (GObject          *object,
+                                                  guint             property_id,
+                                                  const GValue     *value,
+                                                  GParamSpec       *pspec);
+static void       gimp_container_get_property    (GObject          *object,
+                                                  guint             property_id,
+                                                  GValue           *value,
+                                                  GParamSpec       *pspec);
+
+static gint64     gimp_container_get_memsize     (GimpObject       *object,
+                                                  gint64           *gui_size);
+
+static void       gimp_container_real_add        (GimpContainer    *container,
+                                                  GimpObject       *object);
+static void       gimp_container_real_remove     (GimpContainer    *container,
+                                                  GimpObject       *object);
+
+static gboolean   gimp_container_serialize       (GimpConfig       *config,
+                                                  GimpConfigWriter *writer,
+                                                  gpointer          data);
+static gboolean   gimp_container_deserialize     (GimpConfig       *config,
+                                                  GScanner         *scanner,
+                                                  gint              nest_level,
+                                                  gpointer          data);
+
+static void   gimp_container_disconnect_callback (GimpObject       *object,
+                                                  gpointer          data);
+
+static void       gimp_container_free_handler    (GimpContainer    *container,
+                                                  GimpContainerHandler *handler);
+
+
+G_DEFINE_TYPE_WITH_CODE (GimpContainer, gimp_container, GIMP_TYPE_OBJECT,
+                         G_ADD_PRIVATE (GimpContainer)
+                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_CONFIG,
+                                                gimp_container_config_iface_init))
+
+#define parent_class gimp_container_parent_class
+
+static guint container_signals[LAST_SIGNAL] = { 0, };
+
+
+static void
+gimp_container_class_init (GimpContainerClass *klass)
+{
+  GObjectClass    *object_class      = G_OBJECT_CLASS (klass);
+  GimpObjectClass *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+
+  container_signals[ADD] =
+    g_signal_new ("add",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpContainerClass, add),
+                  NULL, NULL,
+                  gimp_marshal_VOID__OBJECT,
+                  G_TYPE_NONE, 1,
+                  GIMP_TYPE_OBJECT);
+
+  container_signals[REMOVE] =
+    g_signal_new ("remove",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpContainerClass, remove),
+                  NULL, NULL,
+                  gimp_marshal_VOID__OBJECT,
+                  G_TYPE_NONE, 1,
+                  GIMP_TYPE_OBJECT);
+
+  container_signals[REORDER] =
+    g_signal_new ("reorder",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpContainerClass, reorder),
+                  NULL, NULL,
+                  gimp_marshal_VOID__OBJECT_INT,
+                  G_TYPE_NONE, 2,
+                  GIMP_TYPE_OBJECT,
+                  G_TYPE_INT);
+
+  container_signals[FREEZE] =
+    g_signal_new ("freeze",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_LAST,
+                  G_STRUCT_OFFSET (GimpContainerClass, freeze),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  container_signals[THAW] =
+    g_signal_new ("thaw",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_LAST,
+                  G_STRUCT_OFFSET (GimpContainerClass, thaw),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  object_class->dispose          = gimp_container_dispose;
+  object_class->set_property     = gimp_container_set_property;
+  object_class->get_property     = gimp_container_get_property;
+
+  gimp_object_class->get_memsize = gimp_container_get_memsize;
+
+  klass->add                     = gimp_container_real_add;
+  klass->remove                  = gimp_container_real_remove;
+  klass->reorder                 = NULL;
+  klass->freeze                  = NULL;
+  klass->thaw                    = NULL;
+
+  klass->clear                   = NULL;
+  klass->have                    = NULL;
+  klass->foreach                 = NULL;
+  klass->search                  = NULL;
+  klass->get_unique_names        = NULL;
+  klass->get_child_by_name       = NULL;
+  klass->get_child_by_index      = NULL;
+  klass->get_child_index         = NULL;
+
+  g_object_class_install_property (object_class, PROP_CHILDREN_TYPE,
+                                   g_param_spec_gtype ("children-type",
+                                                       NULL, NULL,
+                                                       GIMP_TYPE_OBJECT,
+                                                       GIMP_PARAM_READWRITE |
+                                                       G_PARAM_CONSTRUCT_ONLY));
+
+  g_object_class_install_property (object_class, PROP_POLICY,
+                                   g_param_spec_enum ("policy",
+                                                      NULL, NULL,
+                                                      GIMP_TYPE_CONTAINER_POLICY,
+                                                      GIMP_CONTAINER_POLICY_STRONG,
+                                                      GIMP_PARAM_READWRITE |
+                                                      G_PARAM_CONSTRUCT_ONLY));
+}
+
+static void
+gimp_container_config_iface_init (GimpConfigInterface *iface)
+{
+  iface->serialize   = gimp_container_serialize;
+  iface->deserialize = gimp_container_deserialize;
+}
+
+static void
+gimp_container_init (GimpContainer *container)
+{
+  container->priv = gimp_container_get_instance_private (container);
+  container->priv->handlers      = NULL;
+  container->priv->freeze_count  = 0;
+
+  container->priv->children_type = G_TYPE_NONE;
+  container->priv->policy        = GIMP_CONTAINER_POLICY_STRONG;
+  container->priv->n_children    = 0;
+}
+
+static void
+gimp_container_dispose (GObject *object)
+{
+  GimpContainer *container = GIMP_CONTAINER (object);
+
+  gimp_container_clear (container);
+
+  while (container->priv->handlers)
+    gimp_container_remove_handler (container,
+                                   ((GimpContainerHandler *)
+                                    container->priv->handlers->data)->quark);
+
+  if (container->priv->children_type != G_TYPE_NONE)
+    {
+      g_type_class_unref (g_type_class_peek (container->priv->children_type));
+      container->priv->children_type = G_TYPE_NONE;
+    }
+
+  G_OBJECT_CLASS (parent_class)->dispose (object);
+}
+
+static void
+gimp_container_set_property (GObject      *object,
+                             guint         property_id,
+                             const GValue *value,
+                             GParamSpec   *pspec)
+{
+  GimpContainer *container = GIMP_CONTAINER (object);
+
+  switch (property_id)
+    {
+    case PROP_CHILDREN_TYPE:
+      container->priv->children_type = g_value_get_gtype (value);
+      g_type_class_ref (container->priv->children_type);
+      break;
+    case PROP_POLICY:
+      container->priv->policy = g_value_get_enum (value);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_container_get_property (GObject    *object,
+                             guint       property_id,
+                             GValue     *value,
+                             GParamSpec *pspec)
+{
+  GimpContainer *container = GIMP_CONTAINER (object);
+
+  switch (property_id)
+    {
+    case PROP_CHILDREN_TYPE:
+      g_value_set_gtype (value, container->priv->children_type);
+      break;
+    case PROP_POLICY:
+      g_value_set_enum (value, container->priv->policy);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static gint64
+gimp_container_get_memsize (GimpObject *object,
+                            gint64     *gui_size)
+{
+  GimpContainer *container = GIMP_CONTAINER (object);
+  gint64         memsize   = 0;
+  GList         *list;
+
+  for (list = container->priv->handlers; list; list = g_list_next (list))
+    {
+      GimpContainerHandler *handler = list->data;
+
+      memsize += (sizeof (GList) +
+                  sizeof (GimpContainerHandler) +
+                  gimp_string_get_memsize (handler->signame));
+    }
+
+  return memsize + GIMP_OBJECT_CLASS (parent_class)->get_memsize (object,
+                                                                  gui_size);
+}
+
+static void
+gimp_container_real_add (GimpContainer *container,
+                         GimpObject    *object)
+{
+  container->priv->n_children++;
+}
+
+static void
+gimp_container_real_remove (GimpContainer *container,
+                            GimpObject    *object)
+{
+  container->priv->n_children--;
+}
+
+
+typedef struct
+{
+  GimpConfigWriter *writer;
+  gpointer          data;
+  gboolean          success;
+} SerializeData;
+
+static void
+gimp_container_serialize_foreach (GObject       *object,
+                                  SerializeData *serialize_data)
+{
+  GimpConfigInterface *config_iface;
+  const gchar         *name;
+
+  config_iface = GIMP_CONFIG_GET_INTERFACE (object);
+
+  if (! config_iface)
+    serialize_data->success = FALSE;
+
+  if (! serialize_data->success)
+    return;
+
+  gimp_config_writer_open (serialize_data->writer,
+                           g_type_name (G_TYPE_FROM_INSTANCE (object)));
+
+  name = gimp_object_get_name (object);
+
+  if (name)
+    gimp_config_writer_string (serialize_data->writer, name);
+  else
+    gimp_config_writer_print (serialize_data->writer, "NULL", 4);
+
+  serialize_data->success = config_iface->serialize (GIMP_CONFIG (object),
+                                                     serialize_data->writer,
+                                                     serialize_data->data);
+  gimp_config_writer_close (serialize_data->writer);
+}
+
+static gboolean
+gimp_container_serialize (GimpConfig       *config,
+                          GimpConfigWriter *writer,
+                          gpointer          data)
+{
+  GimpContainer *container = GIMP_CONTAINER (config);
+  SerializeData  serialize_data;
+
+  serialize_data.writer  = writer;
+  serialize_data.data    = data;
+  serialize_data.success = TRUE;
+
+  gimp_container_foreach (container,
+                          (GFunc) gimp_container_serialize_foreach,
+                          &serialize_data);
+
+  return serialize_data.success;
+}
+
+static gboolean
+gimp_container_deserialize (GimpConfig *config,
+                            GScanner   *scanner,
+                            gint        nest_level,
+                            gpointer    data)
+{
+  GimpContainer *container = GIMP_CONTAINER (config);
+  GTokenType     token;
+
+  token = G_TOKEN_LEFT_PAREN;
+
+  while (g_scanner_peek_next_token (scanner) == token)
+    {
+      token = g_scanner_get_next_token (scanner);
+
+      switch (token)
+        {
+        case G_TOKEN_LEFT_PAREN:
+          token = G_TOKEN_IDENTIFIER;
+          break;
+
+        case G_TOKEN_IDENTIFIER:
+          {
+            GimpObject *child     = NULL;
+            GType       type;
+            gchar      *name      = NULL;
+            gboolean    add_child = FALSE;
+
+            type = g_type_from_name (scanner->value.v_identifier);
+
+            if (! type)
+              {
+                g_scanner_error (scanner,
+                                 "unable to determine type of '%s'",
+                                 scanner->value.v_identifier);
+                return FALSE;
+              }
+
+            if (! g_type_is_a (type, container->priv->children_type))
+              {
+                g_scanner_error (scanner,
+                                 "'%s' is not a subclass of '%s'",
+                                 scanner->value.v_identifier,
+                                 g_type_name (container->priv->children_type));
+                return FALSE;
+              }
+
+            if (! g_type_is_a (type, GIMP_TYPE_CONFIG))
+              {
+                g_scanner_error (scanner,
+                                 "'%s' does not implement GimpConfigInterface",
+                                 scanner->value.v_identifier);
+                return FALSE;
+              }
+
+            if (! gimp_scanner_parse_string (scanner, &name))
+              {
+                token = G_TOKEN_STRING;
+                break;
+              }
+
+            if (! name)
+              name = g_strdup ("");
+
+            if (gimp_container_get_unique_names (container))
+              child = gimp_container_get_child_by_name (container, name);
+
+            if (! child)
+              {
+                if (GIMP_IS_GIMP (data))
+                  child = g_object_new (type, "gimp", data, NULL);
+                else
+                  child = g_object_new (type, NULL);
+
+                add_child = TRUE;
+              }
+
+            /*  always use the deserialized name. while it normally
+             *  doesn't make a difference there are obscure case like
+             *  template migration.
+             */
+            gimp_object_take_name (child, name);
+
+            if (! GIMP_CONFIG_GET_INTERFACE (child)->deserialize (GIMP_CONFIG (child),
+                                                                  scanner,
+                                                                  nest_level + 1,
+                                                                  NULL))
+              {
+                if (add_child)
+                  g_object_unref (child);
+
+                /*  warning should be already set by child  */
+                return FALSE;
+              }
+
+            if (add_child)
+              {
+                gimp_container_add (container, child);
+
+                if (container->priv->policy == GIMP_CONTAINER_POLICY_STRONG)
+                  g_object_unref (child);
+              }
+          }
+          token = G_TOKEN_RIGHT_PAREN;
+          break;
+
+        case G_TOKEN_RIGHT_PAREN:
+          token = G_TOKEN_LEFT_PAREN;
+          break;
+
+        default: /* do nothing */
+          break;
+        }
+    }
+
+  return gimp_config_deserialize_return (scanner, token, nest_level);
+}
+
+static void
+gimp_container_disconnect_callback (GimpObject *object,
+                                    gpointer    data)
+{
+  GimpContainer *container = GIMP_CONTAINER (data);
+
+  gimp_container_remove (container, object);
+}
+
+static void
+gimp_container_free_handler_foreach_func (GimpObject           *object,
+                                          GimpContainerHandler *handler)
+{
+  gulong handler_id;
+
+  handler_id = GPOINTER_TO_UINT (g_object_get_qdata (G_OBJECT (object),
+                                                     handler->quark));
+
+  if (handler_id)
+    {
+      g_signal_handler_disconnect (object, handler_id);
+
+      g_object_set_qdata (G_OBJECT (object), handler->quark, NULL);
+    }
+}
+
+static void
+gimp_container_free_handler (GimpContainer        *container,
+                             GimpContainerHandler *handler)
+{
+  D (g_print ("%s: id = %d\n", G_STRFUNC, handler->quark));
+
+  gimp_container_foreach (container,
+                          (GFunc) gimp_container_free_handler_foreach_func,
+                          handler);
+
+  g_free (handler->signame);
+  g_slice_free (GimpContainerHandler, handler);
+}
+
+GType
+gimp_container_get_children_type (GimpContainer *container)
+{
+  g_return_val_if_fail (GIMP_IS_CONTAINER (container), G_TYPE_NONE);
+
+  return container->priv->children_type;
+}
+
+GimpContainerPolicy
+gimp_container_get_policy (GimpContainer *container)
+{
+  g_return_val_if_fail (GIMP_IS_CONTAINER (container), 0);
+
+  return container->priv->policy;
+}
+
+gint
+gimp_container_get_n_children (GimpContainer *container)
+{
+  g_return_val_if_fail (GIMP_IS_CONTAINER (container), 0);
+
+  return container->priv->n_children;
+}
+
+gboolean
+gimp_container_add (GimpContainer *container,
+                    GimpObject    *object)
+{
+  GList *list;
+  gint   n_children;
+
+  g_return_val_if_fail (GIMP_IS_CONTAINER (container), FALSE);
+  g_return_val_if_fail (object != NULL, FALSE);
+  g_return_val_if_fail (G_TYPE_CHECK_INSTANCE_TYPE (object,
+                                                    container->priv->children_type),
+                        FALSE);
+
+  if (gimp_container_have (container, object))
+    {
+      g_warning ("%s: container %p already contains object %p",
+                 G_STRFUNC, container, object);
+      return FALSE;
+    }
+
+  for (list = container->priv->handlers; list; list = g_list_next (list))
+    {
+      GimpContainerHandler *handler = list->data;
+      gulong                handler_id;
+
+      handler_id = g_signal_connect (object,
+                                     handler->signame,
+                                     handler->callback,
+                                     handler->callback_data);
+
+      g_object_set_qdata (G_OBJECT (object), handler->quark,
+                          GUINT_TO_POINTER (handler_id));
+    }
+
+  switch (container->priv->policy)
+    {
+    case GIMP_CONTAINER_POLICY_STRONG:
+      g_object_ref (object);
+      break;
+
+    case GIMP_CONTAINER_POLICY_WEAK:
+      g_signal_connect (object, "disconnect",
+                        G_CALLBACK (gimp_container_disconnect_callback),
+                        container);
+      break;
+    }
+
+  n_children = container->priv->n_children;
+
+  g_signal_emit (container, container_signals[ADD], 0, object);
+
+  if (n_children == container->priv->n_children)
+    {
+      g_warning ("%s: GimpContainer::add() implementation did not "
+                 "chain up. Please report this at https://www.gimp.org/bugs/",
+                 G_STRFUNC);
+
+      container->priv->n_children++;
+    }
+
+  return TRUE;
+}
+
+gboolean
+gimp_container_remove (GimpContainer *container,
+                       GimpObject    *object)
+{
+  GList *list;
+  gint   n_children;
+
+  g_return_val_if_fail (GIMP_IS_CONTAINER (container), FALSE);
+  g_return_val_if_fail (object != NULL, FALSE);
+  g_return_val_if_fail (G_TYPE_CHECK_INSTANCE_TYPE (object,
+                                                    container->priv->children_type),
+                        FALSE);
+
+  if (! gimp_container_have (container, object))
+    {
+      g_warning ("%s: container %p does not contain object %p",
+                 G_STRFUNC, container, object);
+      return FALSE;
+    }
+
+  for (list = container->priv->handlers; list; list = g_list_next (list))
+    {
+      GimpContainerHandler *handler = list->data;
+      gulong                handler_id;
+
+      handler_id = GPOINTER_TO_UINT (g_object_get_qdata (G_OBJECT (object),
+                                                         handler->quark));
+
+      if (handler_id)
+        {
+          g_signal_handler_disconnect (object, handler_id);
+
+          g_object_set_qdata (G_OBJECT (object), handler->quark, NULL);
+        }
+    }
+
+  n_children = container->priv->n_children;
+
+  g_signal_emit (container, container_signals[REMOVE], 0, object);
+
+  if (n_children == container->priv->n_children)
+    {
+      g_warning ("%s: GimpContainer::remove() implementation did not "
+                 "chain up. Please report this at https://www.gimp.org/bugs/",
+                 G_STRFUNC);
+
+      container->priv->n_children--;
+    }
+
+  switch (container->priv->policy)
+    {
+    case GIMP_CONTAINER_POLICY_STRONG:
+      g_object_unref (object);
+      break;
+
+    case GIMP_CONTAINER_POLICY_WEAK:
+      g_signal_handlers_disconnect_by_func (object,
+                                            gimp_container_disconnect_callback,
+                                            container);
+      break;
+    }
+
+  return TRUE;
+}
+
+gboolean
+gimp_container_insert (GimpContainer *container,
+                       GimpObject    *object,
+                       gint           index)
+{
+  g_return_val_if_fail (GIMP_IS_CONTAINER (container), FALSE);
+  g_return_val_if_fail (object != NULL, FALSE);
+  g_return_val_if_fail (G_TYPE_CHECK_INSTANCE_TYPE (object,
+                                                    container->priv->children_type),
+                        FALSE);
+
+  g_return_val_if_fail (index >= -1 &&
+                        index <= container->priv->n_children, FALSE);
+
+  if (gimp_container_have (container, object))
+    {
+      g_warning ("%s: container %p already contains object %p",
+                 G_STRFUNC, container, object);
+      return FALSE;
+    }
+
+  if (gimp_container_add (container, object))
+    {
+      return gimp_container_reorder (container, object, index);
+    }
+
+  return FALSE;
+}
+
+gboolean
+gimp_container_reorder (GimpContainer *container,
+                        GimpObject    *object,
+                        gint           new_index)
+{
+  gint index;
+
+  g_return_val_if_fail (GIMP_IS_CONTAINER (container), FALSE);
+  g_return_val_if_fail (object != NULL, FALSE);
+  g_return_val_if_fail (G_TYPE_CHECK_INSTANCE_TYPE (object,
+                                                    container->priv->children_type),
+                        FALSE);
+
+  g_return_val_if_fail (new_index >= -1 &&
+                        new_index < container->priv->n_children, FALSE);
+
+  if (new_index == -1)
+    new_index = container->priv->n_children - 1;
+
+  index = gimp_container_get_child_index (container, object);
+
+  if (index == -1)
+    {
+      g_warning ("%s: container %p does not contain object %p",
+                 G_STRFUNC, container, object);
+      return FALSE;
+    }
+
+  if (index != new_index)
+    g_signal_emit (container, container_signals[REORDER], 0,
+                   object, new_index);
+
+  return TRUE;
+}
+
+void
+gimp_container_freeze (GimpContainer *container)
+{
+  g_return_if_fail (GIMP_IS_CONTAINER (container));
+
+  container->priv->freeze_count++;
+
+  if (container->priv->freeze_count == 1)
+    g_signal_emit (container, container_signals[FREEZE], 0);
+}
+
+void
+gimp_container_thaw (GimpContainer *container)
+{
+  g_return_if_fail (GIMP_IS_CONTAINER (container));
+
+  if (container->priv->freeze_count > 0)
+    container->priv->freeze_count--;
+
+  if (container->priv->freeze_count == 0)
+    g_signal_emit (container, container_signals[THAW], 0);
+}
+
+gboolean
+gimp_container_frozen (GimpContainer *container)
+{
+  g_return_val_if_fail (GIMP_IS_CONTAINER (container), FALSE);
+
+  return (container->priv->freeze_count > 0) ? TRUE : FALSE;
+}
+
+gint
+gimp_container_freeze_count (GimpContainer *container)
+{
+  g_return_val_if_fail (GIMP_IS_CONTAINER (container), 0);
+
+  return container->priv->freeze_count;
+}
+
+void
+gimp_container_clear (GimpContainer *container)
+{
+  g_return_if_fail (GIMP_IS_CONTAINER (container));
+
+  if (container->priv->n_children > 0)
+    {
+      gimp_container_freeze (container);
+      GIMP_CONTAINER_GET_CLASS (container)->clear (container);
+      gimp_container_thaw (container);
+    }
+}
+
+gboolean
+gimp_container_is_empty (GimpContainer *container)
+{
+  g_return_val_if_fail (GIMP_IS_CONTAINER (container), FALSE);
+
+  return (container->priv->n_children == 0);
+}
+
+gboolean
+gimp_container_have (GimpContainer *container,
+                     GimpObject    *object)
+{
+  g_return_val_if_fail (GIMP_IS_CONTAINER (container), FALSE);
+
+  if (container->priv->n_children < 1)
+    return FALSE;
+
+  return GIMP_CONTAINER_GET_CLASS (container)->have (container, object);
+}
+
+void
+gimp_container_foreach (GimpContainer *container,
+                        GFunc          func,
+                        gpointer       user_data)
+{
+  g_return_if_fail (GIMP_IS_CONTAINER (container));
+  g_return_if_fail (func != NULL);
+
+  if (container->priv->n_children > 0)
+    GIMP_CONTAINER_GET_CLASS (container)->foreach (container, func, user_data);
+}
+
+GimpObject *
+gimp_container_search (GimpContainer           *container,
+                       GimpContainerSearchFunc  func,
+                       gpointer                 user_data)
+{
+  g_return_val_if_fail (GIMP_IS_CONTAINER (container), NULL);
+  g_return_val_if_fail (func != NULL, NULL);
+
+  if (container->priv->n_children > 0)
+    {
+      return GIMP_CONTAINER_GET_CLASS (container)->search (container,
+                                                           func, user_data);
+    }
+
+  return NULL;
+}
+
+gboolean
+gimp_container_get_unique_names (GimpContainer *container)
+{
+  g_return_val_if_fail (GIMP_IS_CONTAINER (container), FALSE);
+
+  if (GIMP_CONTAINER_GET_CLASS (container)->get_unique_names)
+    return GIMP_CONTAINER_GET_CLASS (container)->get_unique_names (container);
+
+  return FALSE;
+}
+
+GimpObject *
+gimp_container_get_child_by_name (GimpContainer *container,
+                                  const gchar   *name)
+{
+  g_return_val_if_fail (GIMP_IS_CONTAINER (container), NULL);
+
+  if (!name)
+    return NULL;
+
+  return GIMP_CONTAINER_GET_CLASS (container)->get_child_by_name (container,
+                                                                  name);
+}
+
+GimpObject *
+gimp_container_get_child_by_index (GimpContainer *container,
+                                   gint           index)
+{
+  g_return_val_if_fail (GIMP_IS_CONTAINER (container), NULL);
+
+  if (index < 0 || index >= container->priv->n_children)
+    return NULL;
+
+  return GIMP_CONTAINER_GET_CLASS (container)->get_child_by_index (container,
+                                                                   index);
+}
+
+/**
+ * gimp_container_get_first_child:
+ * @container: a #GimpContainer
+ *
+ * Return value: the first child object stored in @container or %NULL if the
+ *               container is empty
+ */
+GimpObject *
+gimp_container_get_first_child (GimpContainer *container)
+{
+  g_return_val_if_fail (GIMP_IS_CONTAINER (container), NULL);
+
+  if (container->priv->n_children > 0)
+    return GIMP_CONTAINER_GET_CLASS (container)->get_child_by_index (container,
+                                                                     0);
+
+  return NULL;
+}
+
+/**
+ * gimp_container_get_last_child:
+ * @container: a #GimpContainer
+ *
+ * Return value: the last child object stored in @container or %NULL if the
+ *               container is empty
+ */
+GimpObject *
+gimp_container_get_last_child (GimpContainer *container)
+{
+  g_return_val_if_fail (GIMP_IS_CONTAINER (container), NULL);
+
+  if (container->priv->n_children > 0)
+    return GIMP_CONTAINER_GET_CLASS (container)->get_child_by_index (container,
+                                                                     container->priv->n_children - 1);
+
+  return NULL;
+}
+
+gint
+gimp_container_get_child_index (GimpContainer *container,
+                                GimpObject    *object)
+{
+  g_return_val_if_fail (GIMP_IS_CONTAINER (container), -1);
+  g_return_val_if_fail (object != NULL, -1);
+  g_return_val_if_fail (G_TYPE_CHECK_INSTANCE_TYPE (object,
+                                                    container->priv->children_type),
+                        -1);
+
+  return GIMP_CONTAINER_GET_CLASS (container)->get_child_index (container,
+                                                                object);
+}
+
+GimpObject *
+gimp_container_get_neighbor_of (GimpContainer *container,
+                                GimpObject    *object)
+{
+  gint index;
+
+  g_return_val_if_fail (GIMP_IS_CONTAINER (container), NULL);
+  g_return_val_if_fail (GIMP_IS_OBJECT (object), NULL);
+
+  index = gimp_container_get_child_index (container, object);
+
+  if (index != -1)
+    {
+      GimpObject *new;
+
+      new = gimp_container_get_child_by_index (container, index + 1);
+
+      if (! new && index > 0)
+        new = gimp_container_get_child_by_index (container, index - 1);
+
+      return new;
+    }
+
+  return NULL;
+}
+
+static void
+gimp_container_get_name_array_foreach_func (GimpObject   *object,
+                                            gchar      ***iter)
+{
+  gchar **array = *iter;
+
+  *array = g_strdup (gimp_object_get_name (object));
+  (*iter)++;
+}
+
+gchar **
+gimp_container_get_name_array (GimpContainer *container,
+                               gint          *length)
+{
+  gchar **names;
+  gchar **iter;
+
+  g_return_val_if_fail (GIMP_IS_CONTAINER (container), NULL);
+  g_return_val_if_fail (length != NULL, NULL);
+
+  *length = gimp_container_get_n_children (container);
+  if (*length == 0)
+    return NULL;
+
+  names = iter = g_new (gchar *, *length);
+
+  gimp_container_foreach (container,
+                          (GFunc) gimp_container_get_name_array_foreach_func,
+                          &iter);
+
+  return names;
+}
+
+static void
+gimp_container_add_handler_foreach_func (GimpObject           *object,
+                                         GimpContainerHandler *handler)
+{
+  gulong handler_id;
+
+  handler_id = g_signal_connect (object,
+                                 handler->signame,
+                                 handler->callback,
+                                 handler->callback_data);
+
+  g_object_set_qdata (G_OBJECT (object), handler->quark,
+                      GUINT_TO_POINTER (handler_id));
+}
+
+GQuark
+gimp_container_add_handler (GimpContainer *container,
+                            const gchar   *signame,
+                            GCallback      callback,
+                            gpointer       callback_data)
+{
+  GimpContainerHandler *handler;
+  gchar                *key;
+
+  static gint           handler_id = 0;
+
+  g_return_val_if_fail (GIMP_IS_CONTAINER (container), 0);
+  g_return_val_if_fail (signame != NULL, 0);
+  g_return_val_if_fail (callback != NULL, 0);
+
+  if (! g_str_has_prefix (signame, "notify::"))
+    g_return_val_if_fail (g_signal_lookup (signame,
+                                           container->priv->children_type), 0);
+
+  handler = g_slice_new0 (GimpContainerHandler);
+
+  /*  create a unique key for this handler  */
+  key = g_strdup_printf ("%s-%d", signame, handler_id++);
+
+  handler->signame       = g_strdup (signame);
+  handler->callback      = callback;
+  handler->callback_data = callback_data;
+  handler->quark         = g_quark_from_string (key);
+
+  D (g_print ("%s: key = %s, id = %d\n", G_STRFUNC, key, handler->quark));
+
+  g_free (key);
+
+  container->priv->handlers = g_list_prepend (container->priv->handlers, handler);
+
+  gimp_container_foreach (container,
+                          (GFunc) gimp_container_add_handler_foreach_func,
+                          handler);
+
+  return handler->quark;
+}
+
+void
+gimp_container_remove_handler (GimpContainer *container,
+                               GQuark         id)
+{
+  GimpContainerHandler *handler;
+  GList                *list;
+
+  g_return_if_fail (GIMP_IS_CONTAINER (container));
+  g_return_if_fail (id != 0);
+
+  for (list = container->priv->handlers; list; list = g_list_next (list))
+    {
+      handler = (GimpContainerHandler *) list->data;
+
+      if (handler->quark == id)
+        break;
+    }
+
+  if (! list)
+    {
+      g_warning ("%s: tried to remove handler which unknown id %d",
+                 G_STRFUNC, id);
+      return;
+    }
+
+  gimp_container_free_handler (container, handler);
+
+  container->priv->handlers = g_list_delete_link (container->priv->handlers,
+                                                  list);
+}
+
+void
+gimp_container_remove_handlers_by_func (GimpContainer *container,
+                                        GCallback      callback,
+                                        gpointer       callback_data)
+{
+  GList *list;
+
+  g_return_if_fail (GIMP_IS_CONTAINER (container));
+  g_return_if_fail (callback != NULL);
+
+  list = container->priv->handlers;
+
+  while (list)
+    {
+      GimpContainerHandler *handler = list->data;
+      GList                *next    = g_list_next (list);
+
+      if (handler->callback      == callback &&
+          handler->callback_data == callback_data)
+        {
+          gimp_container_free_handler (container, handler);
+
+          container->priv->handlers = g_list_delete_link (
+            container->priv->handlers, list);
+        }
+
+      list = next;
+    }
+}
+
+void
+gimp_container_remove_handlers_by_data (GimpContainer *container,
+                                        gpointer       callback_data)
+{
+  GList *list;
+
+  g_return_if_fail (GIMP_IS_CONTAINER (container));
+
+  list = container->priv->handlers;
+
+  while (list)
+    {
+      GimpContainerHandler *handler = list->data;
+      GList                *next    = g_list_next (list);
+
+      if (handler->callback_data == callback_data)
+        {
+          gimp_container_free_handler (container, handler);
+
+          container->priv->handlers = g_list_delete_link (
+            container->priv->handlers, list);
+        }
+
+      list = next;
+    }
+}
diff --git a/app/core/gimpcontainer.h b/app/core/gimpcontainer.h
new file mode 100644
index 0000000..88465b5
--- /dev/null
+++ b/app/core/gimpcontainer.h
@@ -0,0 +1,150 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1997 Spencer Kimball and Peter Mattis
+ *
+ * gimpcontainer.h
+ * Copyright (C) 2001 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_CONTAINER_H__
+#define __GIMP_CONTAINER_H__
+
+
+#include "gimpobject.h"
+
+
+#define GIMP_TYPE_CONTAINER            (gimp_container_get_type ())
+#define GIMP_CONTAINER(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_CONTAINER, GimpContainer))
+#define GIMP_CONTAINER_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_CONTAINER, GimpContainerClass))
+#define GIMP_IS_CONTAINER(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_CONTAINER))
+#define GIMP_IS_CONTAINER_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_CONTAINER))
+#define GIMP_CONTAINER_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_CONTAINER, GimpContainerClass))
+
+
+typedef gboolean (* GimpContainerSearchFunc) (GimpObject *object,
+                                              gpointer    user_data);
+
+
+typedef struct _GimpContainerClass   GimpContainerClass;
+typedef struct _GimpContainerPrivate GimpContainerPrivate;
+
+struct _GimpContainer
+{
+  GimpObject            parent_instance;
+
+  GimpContainerPrivate *priv;
+};
+
+struct _GimpContainerClass
+{
+  GimpObjectClass  parent_class;
+
+  /*  signals  */
+  void         (* add)                (GimpContainer           *container,
+                                       GimpObject              *object);
+  void         (* remove)             (GimpContainer           *container,
+                                       GimpObject              *object);
+  void         (* reorder)            (GimpContainer           *container,
+                                       GimpObject              *object,
+                                       gint                     new_index);
+  void         (* freeze)             (GimpContainer           *container);
+  void         (* thaw)               (GimpContainer           *container);
+
+  /*  virtual functions  */
+  void         (* clear)              (GimpContainer           *container);
+  gboolean     (* have)               (GimpContainer           *container,
+                                       GimpObject              *object);
+  void         (* foreach)            (GimpContainer           *container,
+                                       GFunc                    func,
+                                       gpointer                 user_data);
+  GimpObject * (* search)             (GimpContainer           *container,
+                                       GimpContainerSearchFunc  func,
+                                       gpointer                 user_data);
+  gboolean     (* get_unique_names)   (GimpContainer           *container);
+  GimpObject * (* get_child_by_name)  (GimpContainer           *container,
+                                       const gchar             *name);
+  GimpObject * (* get_child_by_index) (GimpContainer           *container,
+                                       gint                     index);
+  gint         (* get_child_index)    (GimpContainer           *container,
+                                       GimpObject              *object);
+};
+
+
+GType        gimp_container_get_type           (void) G_GNUC_CONST;
+
+GType        gimp_container_get_children_type  (GimpContainer           *container);
+GimpContainerPolicy gimp_container_get_policy  (GimpContainer           *container);
+gint         gimp_container_get_n_children     (GimpContainer           *container);
+
+gboolean     gimp_container_add                (GimpContainer           *container,
+                                                GimpObject              *object);
+gboolean     gimp_container_remove             (GimpContainer           *container,
+                                                GimpObject              *object);
+gboolean     gimp_container_insert             (GimpContainer           *container,
+                                                GimpObject              *object,
+                                                gint                     new_index);
+gboolean     gimp_container_reorder            (GimpContainer           *container,
+                                                GimpObject              *object,
+                                                gint                     new_index);
+
+void         gimp_container_freeze             (GimpContainer           *container);
+void         gimp_container_thaw               (GimpContainer           *container);
+gboolean     gimp_container_frozen             (GimpContainer           *container);
+gint         gimp_container_freeze_count       (GimpContainer           *container);
+
+void         gimp_container_clear              (GimpContainer           *container);
+gboolean     gimp_container_is_empty           (GimpContainer           *container);
+gboolean     gimp_container_have               (GimpContainer           *container,
+                                                GimpObject              *object);
+void         gimp_container_foreach            (GimpContainer           *container,
+                                                GFunc                    func,
+                                                gpointer                 user_data);
+GimpObject * gimp_container_search             (GimpContainer           *container,
+                                                GimpContainerSearchFunc  func,
+                                                gpointer                 user_data);
+
+gboolean     gimp_container_get_unique_names   (GimpContainer           *container);
+
+GimpObject * gimp_container_get_child_by_name  (GimpContainer           *container,
+                                                const gchar             *name);
+GimpObject * gimp_container_get_child_by_index (GimpContainer           *container,
+                                                gint                     index);
+GimpObject * gimp_container_get_first_child    (GimpContainer           *container);
+GimpObject * gimp_container_get_last_child     (GimpContainer           *container);
+gint         gimp_container_get_child_index    (GimpContainer           *container,
+                                                GimpObject              *object);
+
+GimpObject * gimp_container_get_neighbor_of    (GimpContainer           *container,
+                                                GimpObject              *object);
+
+gchar     ** gimp_container_get_name_array     (GimpContainer           *container,
+                                                gint                    *length);
+
+GQuark       gimp_container_add_handler        (GimpContainer           *container,
+                                                const gchar             *signame,
+                                                GCallback                callback,
+                                                gpointer                 callback_data);
+void         gimp_container_remove_handler     (GimpContainer           *container,
+                                                GQuark                   id);
+void         gimp_container_remove_handlers_by_func
+                                               (GimpContainer           *container,
+                                                GCallback                callback,
+                                                gpointer                 callback_data);
+void         gimp_container_remove_handlers_by_data
+                                               (GimpContainer           *container,
+                                                gpointer                 callback_data);
+
+
+#endif  /* __GIMP_CONTAINER_H__ */
diff --git a/app/core/gimpcontext.c b/app/core/gimpcontext.c
new file mode 100644
index 0000000..3788583
--- /dev/null
+++ b/app/core/gimpcontext.c
@@ -0,0 +1,3828 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpcontext.c
+ * Copyright (C) 1999-2010 Michael Natterer
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <cairo.h>
+#include <gegl.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpcolor/gimpcolor.h"
+#include "libgimpconfig/gimpconfig.h"
+
+#include "core-types.h"
+
+#include "config/gimpcoreconfig.h"
+
+#include "gimp.h"
+#include "gimp-memsize.h"
+#include "gimpbrush.h"
+#include "gimpbuffer.h"
+#include "gimpcontainer.h"
+#include "gimpcontext.h"
+#include "gimpdatafactory.h"
+#include "gimpdynamics.h"
+#include "gimpimagefile.h"
+#include "gimpgradient.h"
+#include "gimpimage.h"
+#include "gimpmarshal.h"
+#include "gimpmybrush.h"
+#include "gimppaintinfo.h"
+#include "gimppalette.h"
+#include "gimppattern.h"
+#include "gimptemplate.h"
+#include "gimptoolinfo.h"
+#include "gimptoolpreset.h"
+
+#include "text/gimpfont.h"
+
+#include "gimp-intl.h"
+
+
+#define RGBA_EPSILON 1e-10
+
+typedef void (* GimpContextCopyPropFunc) (GimpContext *src,
+                                          GimpContext *dest);
+
+#define context_find_defined(context, prop)                              \
+  while (!(((context)->defined_props) & (1 << (prop))) && (context)->parent) \
+    (context) = (context)->parent
+
+#define COPY_NAME(src, dest, member)            \
+  g_free (dest->member);                        \
+  dest->member = g_strdup (src->member)
+
+
+/*  local function prototypes  */
+
+static void    gimp_context_config_iface_init (GimpConfigInterface   *iface);
+
+static void       gimp_context_constructed    (GObject               *object);
+static void       gimp_context_dispose        (GObject               *object);
+static void       gimp_context_finalize       (GObject               *object);
+static void       gimp_context_set_property   (GObject               *object,
+                                               guint                  property_id,
+                                               const GValue          *value,
+                                               GParamSpec            *pspec);
+static void       gimp_context_get_property   (GObject               *object,
+                                               guint                  property_id,
+                                               GValue                *value,
+                                               GParamSpec            *pspec);
+static gint64     gimp_context_get_memsize    (GimpObject            *object,
+                                               gint64                *gui_size);
+
+static gboolean   gimp_context_serialize            (GimpConfig       *config,
+                                                     GimpConfigWriter *writer,
+                                                     gpointer          data);
+static gboolean   gimp_context_deserialize          (GimpConfig       *config,
+                                                     GScanner         *scanner,
+                                                     gint              nest_level,
+                                                     gpointer          data);
+static gboolean   gimp_context_serialize_property   (GimpConfig       *config,
+                                                     guint             property_id,
+                                                     const GValue     *value,
+                                                     GParamSpec       *pspec,
+                                                     GimpConfigWriter *writer);
+static gboolean   gimp_context_deserialize_property (GimpConfig       *config,
+                                                     guint             property_id,
+                                                     GValue           *value,
+                                                     GParamSpec       *pspec,
+                                                     GScanner         *scanner,
+                                                     GTokenType       *expected);
+static GimpConfig * gimp_context_duplicate          (GimpConfig       *config);
+static gboolean     gimp_context_copy               (GimpConfig       *src,
+                                                     GimpConfig       *dest,
+                                                     GParamFlags       flags);
+
+/*  image  */
+static void gimp_context_image_removed       (GimpContainer    *container,
+                                              GimpImage        *image,
+                                              GimpContext      *context);
+static void gimp_context_real_set_image      (GimpContext      *context,
+                                              GimpImage        *image);
+
+/*  display  */
+static void gimp_context_display_removed     (GimpContainer    *container,
+                                              gpointer          display,
+                                              GimpContext      *context);
+static void gimp_context_real_set_display    (GimpContext      *context,
+                                              gpointer          display);
+
+/*  tool  */
+static void gimp_context_tool_dirty          (GimpToolInfo     *tool_info,
+                                              GimpContext      *context);
+static void gimp_context_tool_removed        (GimpContainer    *container,
+                                              GimpToolInfo     *tool_info,
+                                              GimpContext      *context);
+static void gimp_context_tool_list_thaw      (GimpContainer    *container,
+                                              GimpContext      *context);
+static void gimp_context_real_set_tool       (GimpContext      *context,
+                                              GimpToolInfo     *tool_info);
+
+/*  paint info  */
+static void gimp_context_paint_info_dirty    (GimpPaintInfo    *paint_info,
+                                              GimpContext      *context);
+static void gimp_context_paint_info_removed  (GimpContainer    *container,
+                                              GimpPaintInfo    *paint_info,
+                                              GimpContext      *context);
+static void gimp_context_paint_info_list_thaw(GimpContainer    *container,
+                                              GimpContext      *context);
+static void gimp_context_real_set_paint_info (GimpContext      *context,
+                                              GimpPaintInfo    *paint_info);
+
+/*  foreground  */
+static void gimp_context_real_set_foreground (GimpContext      *context,
+                                              const GimpRGB    *color);
+
+/*  background  */
+static void gimp_context_real_set_background (GimpContext      *context,
+                                              const GimpRGB    *color);
+
+/*  opacity  */
+static void gimp_context_real_set_opacity    (GimpContext      *context,
+                                              gdouble           opacity);
+
+/*  paint mode  */
+static void gimp_context_real_set_paint_mode (GimpContext      *context,
+                                              GimpLayerMode     paint_mode);
+
+/*  brush  */
+static void gimp_context_brush_dirty         (GimpBrush        *brush,
+                                              GimpContext      *context);
+static void gimp_context_brush_removed       (GimpContainer    *brush_list,
+                                              GimpBrush        *brush,
+                                              GimpContext      *context);
+static void gimp_context_brush_list_thaw     (GimpContainer    *container,
+                                              GimpContext      *context);
+static void gimp_context_real_set_brush      (GimpContext      *context,
+                                              GimpBrush        *brush);
+
+/*  dynamics  */
+
+static void gimp_context_dynamics_dirty      (GimpDynamics     *dynamics,
+                                              GimpContext      *context);
+static void gimp_context_dynamics_removed    (GimpContainer    *container,
+                                              GimpDynamics     *dynamics,
+                                              GimpContext      *context);
+static void gimp_context_dynamics_list_thaw  (GimpContainer    *container,
+                                              GimpContext      *context);
+static void gimp_context_real_set_dynamics   (GimpContext      *context,
+                                              GimpDynamics     *dynamics);
+
+/*  mybrush  */
+static void gimp_context_mybrush_dirty       (GimpMybrush      *brush,
+                                              GimpContext      *context);
+static void gimp_context_mybrush_removed     (GimpContainer    *brush_list,
+                                              GimpMybrush      *brush,
+                                              GimpContext      *context);
+static void gimp_context_mybrush_list_thaw   (GimpContainer    *container,
+                                              GimpContext      *context);
+static void gimp_context_real_set_mybrush    (GimpContext      *context,
+                                              GimpMybrush      *brush);
+
+/*  pattern  */
+static void gimp_context_pattern_dirty       (GimpPattern      *pattern,
+                                              GimpContext      *context);
+static void gimp_context_pattern_removed     (GimpContainer    *container,
+                                              GimpPattern      *pattern,
+                                              GimpContext      *context);
+static void gimp_context_pattern_list_thaw   (GimpContainer    *container,
+                                              GimpContext      *context);
+static void gimp_context_real_set_pattern    (GimpContext      *context,
+                                              GimpPattern      *pattern);
+
+/*  gradient  */
+static void gimp_context_gradient_dirty      (GimpGradient     *gradient,
+                                              GimpContext      *context);
+static void gimp_context_gradient_removed    (GimpContainer    *container,
+                                              GimpGradient     *gradient,
+                                              GimpContext      *context);
+static void gimp_context_gradient_list_thaw  (GimpContainer    *container,
+                                              GimpContext      *context);
+static void gimp_context_real_set_gradient   (GimpContext      *context,
+                                              GimpGradient     *gradient);
+
+/*  palette  */
+static void gimp_context_palette_dirty       (GimpPalette      *palette,
+                                              GimpContext      *context);
+static void gimp_context_palette_removed     (GimpContainer    *container,
+                                              GimpPalette      *palette,
+                                              GimpContext      *context);
+static void gimp_context_palette_list_thaw   (GimpContainer    *container,
+                                              GimpContext      *context);
+static void gimp_context_real_set_palette    (GimpContext      *context,
+                                              GimpPalette      *palette);
+
+/*  font  */
+static void gimp_context_font_dirty          (GimpFont         *font,
+                                              GimpContext      *context);
+static void gimp_context_font_removed        (GimpContainer    *container,
+                                              GimpFont         *font,
+                                              GimpContext      *context);
+static void gimp_context_font_list_thaw      (GimpContainer    *container,
+                                              GimpContext      *context);
+static void gimp_context_real_set_font       (GimpContext      *context,
+                                              GimpFont         *font);
+
+/*  tool preset  */
+static void gimp_context_tool_preset_dirty     (GimpToolPreset   *tool_preset,
+                                                GimpContext      *context);
+static void gimp_context_tool_preset_removed   (GimpContainer    *container,
+                                                GimpToolPreset   *tool_preset,
+                                                GimpContext      *context);
+static void gimp_context_tool_preset_list_thaw (GimpContainer    *container,
+                                                GimpContext      *context);
+static void gimp_context_real_set_tool_preset  (GimpContext      *context,
+                                                GimpToolPreset   *tool_preset);
+
+/*  buffer  */
+static void gimp_context_buffer_dirty        (GimpBuffer       *buffer,
+                                              GimpContext      *context);
+static void gimp_context_buffer_removed      (GimpContainer    *container,
+                                              GimpBuffer       *buffer,
+                                              GimpContext      *context);
+static void gimp_context_buffer_list_thaw    (GimpContainer    *container,
+                                              GimpContext      *context);
+static void gimp_context_real_set_buffer     (GimpContext      *context,
+                                              GimpBuffer       *buffer);
+
+/*  imagefile  */
+static void gimp_context_imagefile_dirty     (GimpImagefile    *imagefile,
+                                              GimpContext      *context);
+static void gimp_context_imagefile_removed   (GimpContainer    *container,
+                                              GimpImagefile    *imagefile,
+                                              GimpContext      *context);
+static void gimp_context_imagefile_list_thaw (GimpContainer    *container,
+                                              GimpContext      *context);
+static void gimp_context_real_set_imagefile  (GimpContext      *context,
+                                              GimpImagefile    *imagefile);
+
+/*  template  */
+static void gimp_context_template_dirty      (GimpTemplate     *template,
+                                              GimpContext      *context);
+static void gimp_context_template_removed    (GimpContainer    *container,
+                                              GimpTemplate     *template,
+                                              GimpContext      *context);
+static void gimp_context_template_list_thaw  (GimpContainer    *container,
+                                              GimpContext      *context);
+static void gimp_context_real_set_template   (GimpContext      *context,
+                                              GimpTemplate     *template);
+
+
+/*  utilities  */
+static gpointer gimp_context_find_object     (GimpContext      *context,
+                                              GimpContainer    *container,
+                                              const gchar      *object_name,
+                                              gpointer          standard_object);
+
+
+/*  properties & signals  */
+
+enum
+{
+  GIMP_CONTEXT_PROP_0,
+  GIMP_CONTEXT_PROP_GIMP
+
+  /*  remaining values are in core-enums.h  (GimpContextPropType)  */
+};
+
+enum
+{
+  DUMMY_0,
+  DUMMY_1,
+  IMAGE_CHANGED,
+  DISPLAY_CHANGED,
+  TOOL_CHANGED,
+  PAINT_INFO_CHANGED,
+  FOREGROUND_CHANGED,
+  BACKGROUND_CHANGED,
+  OPACITY_CHANGED,
+  PAINT_MODE_CHANGED,
+  BRUSH_CHANGED,
+  DYNAMICS_CHANGED,
+  MYBRUSH_CHANGED,
+  PATTERN_CHANGED,
+  GRADIENT_CHANGED,
+  PALETTE_CHANGED,
+  FONT_CHANGED,
+  TOOL_PRESET_CHANGED,
+  BUFFER_CHANGED,
+  IMAGEFILE_CHANGED,
+  TEMPLATE_CHANGED,
+  PROP_NAME_CHANGED,
+  LAST_SIGNAL
+};
+
+static const gchar * const gimp_context_prop_names[] =
+{
+  NULL, /* PROP_0 */
+  "gimp",
+  "image",
+  "display",
+  "tool",
+  "paint-info",
+  "foreground",
+  "background",
+  "opacity",
+  "paint-mode",
+  "brush",
+  "dynamics",
+  "mybrush",
+  "pattern",
+  "gradient",
+  "palette",
+  "font",
+  "tool-preset",
+  "buffer",
+  "imagefile",
+  "template"
+};
+
+static GType gimp_context_prop_types[] =
+{
+  G_TYPE_NONE, /* PROP_0    */
+  G_TYPE_NONE, /* PROP_GIMP */
+  0,
+  G_TYPE_NONE,
+  0,
+  0,
+  G_TYPE_NONE,
+  G_TYPE_NONE,
+  G_TYPE_NONE,
+  G_TYPE_NONE,
+  0,
+  0,
+  0,
+  0,
+  0,
+  0,
+  0,
+  0,
+  0,
+  0,
+  0
+};
+
+
+G_DEFINE_TYPE_WITH_CODE (GimpContext, gimp_context, GIMP_TYPE_VIEWABLE,
+                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_CONFIG,
+                                                gimp_context_config_iface_init))
+
+#define parent_class gimp_context_parent_class
+
+static GimpConfigInterface *parent_config_iface = NULL;
+
+static guint gimp_context_signals[LAST_SIGNAL] = { 0 };
+
+
+static void
+gimp_context_class_init (GimpContextClass *klass)
+{
+  GObjectClass    *object_class      = G_OBJECT_CLASS (klass);
+  GimpObjectClass *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+  GimpRGB          black;
+  GimpRGB          white;
+
+  gimp_rgba_set (&black, 0.0, 0.0, 0.0, GIMP_OPACITY_OPAQUE);
+  gimp_rgba_set (&white, 1.0, 1.0, 1.0, GIMP_OPACITY_OPAQUE);
+
+  gimp_context_signals[IMAGE_CHANGED] =
+    g_signal_new ("image-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpContextClass, image_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__OBJECT,
+                  G_TYPE_NONE, 1,
+                  GIMP_TYPE_IMAGE);
+
+  gimp_context_signals[DISPLAY_CHANGED] =
+    g_signal_new ("display-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpContextClass, display_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__OBJECT,
+                  G_TYPE_NONE, 1,
+                  GIMP_TYPE_OBJECT);
+
+  gimp_context_signals[TOOL_CHANGED] =
+    g_signal_new ("tool-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpContextClass, tool_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__OBJECT,
+                  G_TYPE_NONE, 1,
+                  GIMP_TYPE_TOOL_INFO);
+
+  gimp_context_signals[PAINT_INFO_CHANGED] =
+    g_signal_new ("paint-info-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpContextClass, paint_info_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__OBJECT,
+                  G_TYPE_NONE, 1,
+                  GIMP_TYPE_PAINT_INFO);
+
+  gimp_context_signals[FOREGROUND_CHANGED] =
+    g_signal_new ("foreground-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpContextClass, foreground_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__BOXED,
+                  G_TYPE_NONE, 1,
+                  GIMP_TYPE_RGB | G_SIGNAL_TYPE_STATIC_SCOPE);
+
+  gimp_context_signals[BACKGROUND_CHANGED] =
+    g_signal_new ("background-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpContextClass, background_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__BOXED,
+                  G_TYPE_NONE, 1,
+                  GIMP_TYPE_RGB | G_SIGNAL_TYPE_STATIC_SCOPE);
+
+  gimp_context_signals[OPACITY_CHANGED] =
+    g_signal_new ("opacity-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpContextClass, opacity_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__DOUBLE,
+                  G_TYPE_NONE, 1,
+                  G_TYPE_DOUBLE);
+
+  gimp_context_signals[PAINT_MODE_CHANGED] =
+    g_signal_new ("paint-mode-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpContextClass, paint_mode_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__ENUM,
+                  G_TYPE_NONE, 1,
+                  GIMP_TYPE_LAYER_MODE);
+
+  gimp_context_signals[BRUSH_CHANGED] =
+    g_signal_new ("brush-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpContextClass, brush_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__OBJECT,
+                  G_TYPE_NONE, 1,
+                  GIMP_TYPE_BRUSH);
+
+  gimp_context_signals[DYNAMICS_CHANGED] =
+    g_signal_new ("dynamics-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpContextClass, dynamics_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__OBJECT,
+                  G_TYPE_NONE, 1,
+                  GIMP_TYPE_DYNAMICS);
+
+  gimp_context_signals[MYBRUSH_CHANGED] =
+    g_signal_new ("mybrush-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpContextClass, mybrush_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__OBJECT,
+                  G_TYPE_NONE, 1,
+                  GIMP_TYPE_MYBRUSH);
+
+  gimp_context_signals[PATTERN_CHANGED] =
+    g_signal_new ("pattern-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpContextClass, pattern_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__OBJECT,
+                  G_TYPE_NONE, 1,
+                  GIMP_TYPE_PATTERN);
+
+  gimp_context_signals[GRADIENT_CHANGED] =
+    g_signal_new ("gradient-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpContextClass, gradient_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__OBJECT,
+                  G_TYPE_NONE, 1,
+                  GIMP_TYPE_GRADIENT);
+
+  gimp_context_signals[PALETTE_CHANGED] =
+    g_signal_new ("palette-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpContextClass, palette_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__OBJECT,
+                  G_TYPE_NONE, 1,
+                  GIMP_TYPE_PALETTE);
+
+  gimp_context_signals[FONT_CHANGED] =
+    g_signal_new ("font-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpContextClass, font_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__OBJECT,
+                  G_TYPE_NONE, 1,
+                  GIMP_TYPE_FONT);
+
+  gimp_context_signals[TOOL_PRESET_CHANGED] =
+    g_signal_new ("tool-preset-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpContextClass, tool_preset_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__OBJECT,
+                  G_TYPE_NONE, 1,
+                  GIMP_TYPE_TOOL_PRESET);
+
+  gimp_context_signals[BUFFER_CHANGED] =
+    g_signal_new ("buffer-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpContextClass, buffer_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__OBJECT,
+                  G_TYPE_NONE, 1,
+                  GIMP_TYPE_BUFFER);
+
+  gimp_context_signals[IMAGEFILE_CHANGED] =
+    g_signal_new ("imagefile-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpContextClass, imagefile_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__OBJECT,
+                  G_TYPE_NONE, 1,
+                  GIMP_TYPE_IMAGEFILE);
+
+  gimp_context_signals[TEMPLATE_CHANGED] =
+    g_signal_new ("template-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpContextClass, template_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__OBJECT,
+                  G_TYPE_NONE, 1,
+                  GIMP_TYPE_TEMPLATE);
+
+  gimp_context_signals[PROP_NAME_CHANGED] =
+    g_signal_new ("prop-name-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpContextClass, prop_name_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__INT,
+                  G_TYPE_NONE, 1,
+                  G_TYPE_INT);
+
+  object_class->constructed      = gimp_context_constructed;
+  object_class->set_property     = gimp_context_set_property;
+  object_class->get_property     = gimp_context_get_property;
+  object_class->dispose          = gimp_context_dispose;
+  object_class->finalize         = gimp_context_finalize;
+
+  gimp_object_class->get_memsize = gimp_context_get_memsize;
+
+  klass->image_changed           = NULL;
+  klass->display_changed         = NULL;
+  klass->tool_changed            = NULL;
+  klass->paint_info_changed      = NULL;
+  klass->foreground_changed      = NULL;
+  klass->background_changed      = NULL;
+  klass->opacity_changed         = NULL;
+  klass->paint_mode_changed      = NULL;
+  klass->brush_changed           = NULL;
+  klass->dynamics_changed        = NULL;
+  klass->mybrush_changed         = NULL;
+  klass->pattern_changed         = NULL;
+  klass->gradient_changed        = NULL;
+  klass->palette_changed         = NULL;
+  klass->font_changed            = NULL;
+  klass->tool_preset_changed     = NULL;
+  klass->buffer_changed          = NULL;
+  klass->imagefile_changed       = NULL;
+  klass->template_changed        = NULL;
+  klass->prop_name_changed       = NULL;
+
+  gimp_context_prop_types[GIMP_CONTEXT_PROP_IMAGE]       = GIMP_TYPE_IMAGE;
+  gimp_context_prop_types[GIMP_CONTEXT_PROP_TOOL]        = GIMP_TYPE_TOOL_INFO;
+  gimp_context_prop_types[GIMP_CONTEXT_PROP_PAINT_INFO]  = GIMP_TYPE_PAINT_INFO;
+  gimp_context_prop_types[GIMP_CONTEXT_PROP_BRUSH]       = GIMP_TYPE_BRUSH;
+  gimp_context_prop_types[GIMP_CONTEXT_PROP_DYNAMICS]    = GIMP_TYPE_DYNAMICS;
+  gimp_context_prop_types[GIMP_CONTEXT_PROP_MYBRUSH]     = GIMP_TYPE_MYBRUSH;
+  gimp_context_prop_types[GIMP_CONTEXT_PROP_PATTERN]     = GIMP_TYPE_PATTERN;
+  gimp_context_prop_types[GIMP_CONTEXT_PROP_GRADIENT]    = GIMP_TYPE_GRADIENT;
+  gimp_context_prop_types[GIMP_CONTEXT_PROP_PALETTE]     = GIMP_TYPE_PALETTE;
+  gimp_context_prop_types[GIMP_CONTEXT_PROP_FONT]        = GIMP_TYPE_FONT;
+  gimp_context_prop_types[GIMP_CONTEXT_PROP_TOOL_PRESET] = GIMP_TYPE_TOOL_PRESET;
+  gimp_context_prop_types[GIMP_CONTEXT_PROP_BUFFER]      = GIMP_TYPE_BUFFER;
+  gimp_context_prop_types[GIMP_CONTEXT_PROP_IMAGEFILE]   = GIMP_TYPE_IMAGEFILE;
+  gimp_context_prop_types[GIMP_CONTEXT_PROP_TEMPLATE]    = GIMP_TYPE_TEMPLATE;
+
+  g_object_class_install_property (object_class, GIMP_CONTEXT_PROP_GIMP,
+                                   g_param_spec_object ("gimp",
+                                                        NULL, NULL,
+                                                        GIMP_TYPE_GIMP,
+                                                        GIMP_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT_ONLY));
+
+  g_object_class_install_property (object_class, GIMP_CONTEXT_PROP_IMAGE,
+                                   g_param_spec_object (gimp_context_prop_names[GIMP_CONTEXT_PROP_IMAGE],
+                                                        NULL, NULL,
+                                                        GIMP_TYPE_IMAGE,
+                                                        GIMP_PARAM_READWRITE));
+
+  g_object_class_install_property (object_class, GIMP_CONTEXT_PROP_DISPLAY,
+                                   g_param_spec_object (gimp_context_prop_names[GIMP_CONTEXT_PROP_DISPLAY],
+                                                        NULL, NULL,
+                                                        GIMP_TYPE_OBJECT,
+                                                        GIMP_PARAM_READWRITE));
+
+  GIMP_CONFIG_PROP_OBJECT (object_class, GIMP_CONTEXT_PROP_TOOL,
+                           gimp_context_prop_names[GIMP_CONTEXT_PROP_TOOL],
+                           NULL, NULL,
+                           GIMP_TYPE_TOOL_INFO,
+                           GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_OBJECT (object_class, GIMP_CONTEXT_PROP_PAINT_INFO,
+                           gimp_context_prop_names[GIMP_CONTEXT_PROP_PAINT_INFO],
+                           NULL, NULL,
+                           GIMP_TYPE_PAINT_INFO,
+                           GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_RGB (object_class, GIMP_CONTEXT_PROP_FOREGROUND,
+                        gimp_context_prop_names[GIMP_CONTEXT_PROP_FOREGROUND],
+                        _("Foreground"),
+                        _("Foreground color"),
+                         FALSE, &black,
+                        GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_RGB (object_class, GIMP_CONTEXT_PROP_BACKGROUND,
+                        gimp_context_prop_names[GIMP_CONTEXT_PROP_BACKGROUND],
+                        _("Background"),
+                        _("Background color"),
+                        FALSE, &white,
+                        GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_DOUBLE (object_class, GIMP_CONTEXT_PROP_OPACITY,
+                           gimp_context_prop_names[GIMP_CONTEXT_PROP_OPACITY],
+                           _("Opacity"),
+                           _("Opacity"),
+                           GIMP_OPACITY_TRANSPARENT,
+                           GIMP_OPACITY_OPAQUE,
+                           GIMP_OPACITY_OPAQUE,
+                           GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_ENUM (object_class, GIMP_CONTEXT_PROP_PAINT_MODE,
+                         gimp_context_prop_names[GIMP_CONTEXT_PROP_PAINT_MODE],
+                         _("Paint Mode"),
+                         _("Paint Mode"),
+                         GIMP_TYPE_LAYER_MODE,
+                         GIMP_LAYER_MODE_NORMAL,
+                         GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_OBJECT (object_class, GIMP_CONTEXT_PROP_BRUSH,
+                           gimp_context_prop_names[GIMP_CONTEXT_PROP_BRUSH],
+                           _("Brush"),
+                           _("Brush"),
+                           GIMP_TYPE_BRUSH,
+                           GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_OBJECT (object_class, GIMP_CONTEXT_PROP_DYNAMICS,
+                           gimp_context_prop_names[GIMP_CONTEXT_PROP_DYNAMICS],
+                           _("Dynamics"),
+                           _("Paint dynamics"),
+                           GIMP_TYPE_DYNAMICS,
+                           GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_OBJECT (object_class, GIMP_CONTEXT_PROP_MYBRUSH,
+                           gimp_context_prop_names[GIMP_CONTEXT_PROP_MYBRUSH],
+                           _("MyPaint Brush"),
+                           _("MyPaint Brush"),
+                           GIMP_TYPE_MYBRUSH,
+                           GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_OBJECT (object_class, GIMP_CONTEXT_PROP_PATTERN,
+                           gimp_context_prop_names[GIMP_CONTEXT_PROP_PATTERN],
+                           _("Pattern"),
+                           _("Pattern"),
+                           GIMP_TYPE_PATTERN,
+                           GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_OBJECT (object_class, GIMP_CONTEXT_PROP_GRADIENT,
+                           gimp_context_prop_names[GIMP_CONTEXT_PROP_GRADIENT],
+                           _("Gradient"),
+                           _("Gradient"),
+                           GIMP_TYPE_GRADIENT,
+                           GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_OBJECT (object_class, GIMP_CONTEXT_PROP_PALETTE,
+                           gimp_context_prop_names[GIMP_CONTEXT_PROP_PALETTE],
+                           _("Palette"),
+                           _("Palette"),
+                           GIMP_TYPE_PALETTE,
+                           GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_OBJECT (object_class, GIMP_CONTEXT_PROP_FONT,
+                           gimp_context_prop_names[GIMP_CONTEXT_PROP_FONT],
+                           _("Font"),
+                           _("Font"),
+                           GIMP_TYPE_FONT,
+                           GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_OBJECT (object_class, GIMP_CONTEXT_PROP_TOOL_PRESET,
+                           gimp_context_prop_names[GIMP_CONTEXT_PROP_TOOL_PRESET],
+                           _("Tool Preset"),
+                           _("Tool Preset"),
+                           GIMP_TYPE_TOOL_PRESET,
+                           GIMP_PARAM_STATIC_STRINGS);
+
+  g_object_class_install_property (object_class, GIMP_CONTEXT_PROP_BUFFER,
+                                   g_param_spec_object (gimp_context_prop_names[GIMP_CONTEXT_PROP_BUFFER],
+                                                        NULL, NULL,
+                                                        GIMP_TYPE_BUFFER,
+                                                        GIMP_PARAM_READWRITE));
+
+  g_object_class_install_property (object_class, GIMP_CONTEXT_PROP_IMAGEFILE,
+                                   g_param_spec_object (gimp_context_prop_names[GIMP_CONTEXT_PROP_IMAGEFILE],
+                                                        NULL, NULL,
+                                                        GIMP_TYPE_IMAGEFILE,
+                                                        GIMP_PARAM_READWRITE));
+
+  g_object_class_install_property (object_class, GIMP_CONTEXT_PROP_TEMPLATE,
+                                   g_param_spec_object (gimp_context_prop_names[GIMP_CONTEXT_PROP_TEMPLATE],
+                                                        NULL, NULL,
+                                                        GIMP_TYPE_TEMPLATE,
+                                                        GIMP_PARAM_READWRITE));
+}
+
+static void
+gimp_context_init (GimpContext *context)
+{
+  context->gimp            = NULL;
+
+  context->parent          = NULL;
+
+  context->defined_props   = GIMP_CONTEXT_PROP_MASK_ALL;
+  context->serialize_props = GIMP_CONTEXT_PROP_MASK_ALL;
+
+  context->image           = NULL;
+  context->display         = NULL;
+
+  context->tool_info       = NULL;
+  context->tool_name       = NULL;
+
+  context->paint_info      = NULL;
+  context->paint_name      = NULL;
+
+  context->brush           = NULL;
+  context->brush_name      = NULL;
+
+  context->dynamics        = NULL;
+  context->dynamics_name   = NULL;
+
+  context->mybrush         = NULL;
+  context->mybrush_name    = NULL;
+
+  context->pattern         = NULL;
+  context->pattern_name    = NULL;
+
+  context->gradient        = NULL;
+  context->gradient_name   = NULL;
+
+  context->palette         = NULL;
+  context->palette_name    = NULL;
+
+  context->font            = NULL;
+  context->font_name       = NULL;
+
+  context->tool_preset      = NULL;
+  context->tool_preset_name = NULL;
+
+  context->buffer          = NULL;
+  context->buffer_name     = NULL;
+
+  context->imagefile       = NULL;
+  context->imagefile_name  = NULL;
+
+  context->template        = NULL;
+  context->template_name   = NULL;
+}
+
+static void
+gimp_context_config_iface_init (GimpConfigInterface *iface)
+{
+  parent_config_iface = g_type_interface_peek_parent (iface);
+
+  if (! parent_config_iface)
+    parent_config_iface = g_type_default_interface_peek (GIMP_TYPE_CONFIG);
+
+  iface->serialize            = gimp_context_serialize;
+  iface->deserialize          = gimp_context_deserialize;
+  iface->serialize_property   = gimp_context_serialize_property;
+  iface->deserialize_property = gimp_context_deserialize_property;
+  iface->duplicate            = gimp_context_duplicate;
+  iface->copy                 = gimp_context_copy;
+}
+
+static void
+gimp_context_constructed (GObject *object)
+{
+  Gimp          *gimp;
+  GimpContainer *container;
+
+  G_OBJECT_CLASS (parent_class)->constructed (object);
+
+  gimp = GIMP_CONTEXT (object)->gimp;
+
+  gimp_assert (GIMP_IS_GIMP (gimp));
+
+  gimp->context_list = g_list_prepend (gimp->context_list, object);
+
+  g_signal_connect_object (gimp->images, "remove",
+                           G_CALLBACK (gimp_context_image_removed),
+                           object, 0);
+  g_signal_connect_object (gimp->displays, "remove",
+                           G_CALLBACK (gimp_context_display_removed),
+                           object, 0);
+
+  g_signal_connect_object (gimp->tool_info_list, "remove",
+                           G_CALLBACK (gimp_context_tool_removed),
+                           object, 0);
+  g_signal_connect_object (gimp->tool_info_list, "thaw",
+                           G_CALLBACK (gimp_context_tool_list_thaw),
+                           object, 0);
+
+  g_signal_connect_object (gimp->paint_info_list, "remove",
+                           G_CALLBACK (gimp_context_paint_info_removed),
+                           object, 0);
+  g_signal_connect_object (gimp->paint_info_list, "thaw",
+                           G_CALLBACK (gimp_context_paint_info_list_thaw),
+                           object, 0);
+
+  container = gimp_data_factory_get_container (gimp->brush_factory);
+  g_signal_connect_object (container, "remove",
+                           G_CALLBACK (gimp_context_brush_removed),
+                           object, 0);
+  g_signal_connect_object (container, "thaw",
+                           G_CALLBACK (gimp_context_brush_list_thaw),
+                           object, 0);
+
+  container = gimp_data_factory_get_container (gimp->dynamics_factory);
+  g_signal_connect_object (container, "remove",
+                           G_CALLBACK (gimp_context_dynamics_removed),
+                           object, 0);
+  g_signal_connect_object (container, "thaw",
+                           G_CALLBACK (gimp_context_dynamics_list_thaw),
+                           object, 0);
+
+  container = gimp_data_factory_get_container (gimp->mybrush_factory);
+  g_signal_connect_object (container, "remove",
+                           G_CALLBACK (gimp_context_mybrush_removed),
+                           object, 0);
+  g_signal_connect_object (container, "thaw",
+                           G_CALLBACK (gimp_context_mybrush_list_thaw),
+                           object, 0);
+
+  container = gimp_data_factory_get_container (gimp->pattern_factory);
+  g_signal_connect_object (container, "remove",
+                           G_CALLBACK (gimp_context_pattern_removed),
+                           object, 0);
+  g_signal_connect_object (container, "thaw",
+                           G_CALLBACK (gimp_context_pattern_list_thaw),
+                           object, 0);
+
+  container = gimp_data_factory_get_container (gimp->gradient_factory);
+  g_signal_connect_object (container, "remove",
+                           G_CALLBACK (gimp_context_gradient_removed),
+                           object, 0);
+  g_signal_connect_object (container, "thaw",
+                           G_CALLBACK (gimp_context_gradient_list_thaw),
+                           object, 0);
+
+  container = gimp_data_factory_get_container (gimp->palette_factory);
+  g_signal_connect_object (container, "remove",
+                           G_CALLBACK (gimp_context_palette_removed),
+                           object, 0);
+  g_signal_connect_object (container, "thaw",
+                           G_CALLBACK (gimp_context_palette_list_thaw),
+                           object, 0);
+
+  container = gimp_data_factory_get_container (gimp->font_factory);
+  g_signal_connect_object (container, "remove",
+                           G_CALLBACK (gimp_context_font_removed),
+                           object, 0);
+  g_signal_connect_object (container, "thaw",
+                           G_CALLBACK (gimp_context_font_list_thaw),
+                           object, 0);
+
+  container = gimp_data_factory_get_container (gimp->tool_preset_factory);
+  g_signal_connect_object (container, "remove",
+                           G_CALLBACK (gimp_context_tool_preset_removed),
+                           object, 0);
+  g_signal_connect_object (container, "thaw",
+                           G_CALLBACK (gimp_context_tool_preset_list_thaw),
+                           object, 0);
+
+  g_signal_connect_object (gimp->named_buffers, "remove",
+                           G_CALLBACK (gimp_context_buffer_removed),
+                           object, 0);
+  g_signal_connect_object (gimp->named_buffers, "thaw",
+                           G_CALLBACK (gimp_context_buffer_list_thaw),
+                           object, 0);
+
+  g_signal_connect_object (gimp->documents, "remove",
+                           G_CALLBACK (gimp_context_imagefile_removed),
+                           object, 0);
+  g_signal_connect_object (gimp->documents, "thaw",
+                           G_CALLBACK (gimp_context_imagefile_list_thaw),
+                           object, 0);
+
+  g_signal_connect_object (gimp->templates, "remove",
+                           G_CALLBACK (gimp_context_template_removed),
+                           object, 0);
+  g_signal_connect_object (gimp->templates, "thaw",
+                           G_CALLBACK (gimp_context_template_list_thaw),
+                           object, 0);
+
+  gimp_context_set_paint_info (GIMP_CONTEXT (object),
+                               gimp_paint_info_get_standard (gimp));
+}
+
+static void
+gimp_context_dispose (GObject *object)
+{
+  GimpContext *context = GIMP_CONTEXT (object);
+
+  gimp_context_set_parent (context, NULL);
+
+  if (context->gimp)
+    {
+      context->gimp->context_list = g_list_remove (context->gimp->context_list,
+                                                   context);
+      context->gimp = NULL;
+    }
+
+  g_clear_object (&context->tool_info);
+  g_clear_object (&context->paint_info);
+  g_clear_object (&context->brush);
+  g_clear_object (&context->dynamics);
+  g_clear_object (&context->mybrush);
+  g_clear_object (&context->pattern);
+  g_clear_object (&context->gradient);
+  g_clear_object (&context->palette);
+  g_clear_object (&context->font);
+  g_clear_object (&context->tool_preset);
+  g_clear_object (&context->buffer);
+  g_clear_object (&context->imagefile);
+  g_clear_object (&context->template);
+
+  G_OBJECT_CLASS (parent_class)->dispose (object);
+}
+
+static void
+gimp_context_finalize (GObject *object)
+{
+  GimpContext *context = GIMP_CONTEXT (object);
+
+  context->parent  = NULL;
+  context->image   = NULL;
+  context->display = NULL;
+
+  g_clear_pointer (&context->tool_name,        g_free);
+  g_clear_pointer (&context->paint_name,       g_free);
+  g_clear_pointer (&context->brush_name,       g_free);
+  g_clear_pointer (&context->dynamics_name,    g_free);
+  g_clear_pointer (&context->mybrush_name,     g_free);
+  g_clear_pointer (&context->pattern_name,     g_free);
+  g_clear_pointer (&context->gradient_name,    g_free);
+  g_clear_pointer (&context->palette_name,     g_free);
+  g_clear_pointer (&context->font_name,        g_free);
+  g_clear_pointer (&context->tool_preset_name, g_free);
+  g_clear_pointer (&context->buffer_name,      g_free);
+  g_clear_pointer (&context->imagefile_name,   g_free);
+  g_clear_pointer (&context->template_name,    g_free);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gimp_context_set_property (GObject      *object,
+                           guint         property_id,
+                           const GValue *value,
+                           GParamSpec   *pspec)
+{
+  GimpContext *context = GIMP_CONTEXT (object);
+
+  switch (property_id)
+    {
+    case GIMP_CONTEXT_PROP_GIMP:
+      context->gimp = g_value_get_object (value);
+      break;
+    case GIMP_CONTEXT_PROP_IMAGE:
+      gimp_context_set_image (context, g_value_get_object (value));
+      break;
+    case GIMP_CONTEXT_PROP_DISPLAY:
+      gimp_context_set_display (context, g_value_get_object (value));
+      break;
+    case GIMP_CONTEXT_PROP_TOOL:
+      gimp_context_set_tool (context, g_value_get_object (value));
+      break;
+    case GIMP_CONTEXT_PROP_PAINT_INFO:
+      gimp_context_set_paint_info (context, g_value_get_object (value));
+      break;
+    case GIMP_CONTEXT_PROP_FOREGROUND:
+      gimp_context_set_foreground (context, g_value_get_boxed (value));
+      break;
+    case GIMP_CONTEXT_PROP_BACKGROUND:
+      gimp_context_set_background (context, g_value_get_boxed (value));
+      break;
+    case GIMP_CONTEXT_PROP_OPACITY:
+      gimp_context_set_opacity (context, g_value_get_double (value));
+      break;
+    case GIMP_CONTEXT_PROP_PAINT_MODE:
+      gimp_context_set_paint_mode (context, g_value_get_enum (value));
+      break;
+    case GIMP_CONTEXT_PROP_BRUSH:
+      gimp_context_set_brush (context, g_value_get_object (value));
+      break;
+    case GIMP_CONTEXT_PROP_DYNAMICS:
+      gimp_context_set_dynamics (context, g_value_get_object (value));
+      break;
+    case GIMP_CONTEXT_PROP_MYBRUSH:
+      gimp_context_set_mybrush (context, g_value_get_object (value));
+      break;
+    case GIMP_CONTEXT_PROP_PATTERN:
+      gimp_context_set_pattern (context, g_value_get_object (value));
+      break;
+    case GIMP_CONTEXT_PROP_GRADIENT:
+      gimp_context_set_gradient (context, g_value_get_object (value));
+      break;
+    case GIMP_CONTEXT_PROP_PALETTE:
+      gimp_context_set_palette (context, g_value_get_object (value));
+      break;
+    case GIMP_CONTEXT_PROP_FONT:
+      gimp_context_set_font (context, g_value_get_object (value));
+      break;
+    case GIMP_CONTEXT_PROP_TOOL_PRESET:
+      gimp_context_set_tool_preset (context, g_value_get_object (value));
+      break;
+    case GIMP_CONTEXT_PROP_BUFFER:
+      gimp_context_set_buffer (context, g_value_get_object (value));
+      break;
+    case GIMP_CONTEXT_PROP_IMAGEFILE:
+      gimp_context_set_imagefile (context, g_value_get_object (value));
+      break;
+    case GIMP_CONTEXT_PROP_TEMPLATE:
+      gimp_context_set_template (context, g_value_get_object (value));
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_context_get_property (GObject    *object,
+                           guint       property_id,
+                           GValue     *value,
+                           GParamSpec *pspec)
+{
+  GimpContext *context = GIMP_CONTEXT (object);
+
+  switch (property_id)
+    {
+    case GIMP_CONTEXT_PROP_GIMP:
+      g_value_set_object (value, context->gimp);
+      break;
+    case GIMP_CONTEXT_PROP_IMAGE:
+      g_value_set_object (value, gimp_context_get_image (context));
+      break;
+    case GIMP_CONTEXT_PROP_DISPLAY:
+      g_value_set_object (value, gimp_context_get_display (context));
+      break;
+    case GIMP_CONTEXT_PROP_TOOL:
+      g_value_set_object (value, gimp_context_get_tool (context));
+      break;
+    case GIMP_CONTEXT_PROP_PAINT_INFO:
+      g_value_set_object (value, gimp_context_get_paint_info (context));
+      break;
+    case GIMP_CONTEXT_PROP_FOREGROUND:
+      {
+        GimpRGB color;
+
+        gimp_context_get_foreground (context, &color);
+        g_value_set_boxed (value, &color);
+      }
+      break;
+    case GIMP_CONTEXT_PROP_BACKGROUND:
+      {
+        GimpRGB color;
+
+        gimp_context_get_background (context, &color);
+        g_value_set_boxed (value, &color);
+      }
+      break;
+    case GIMP_CONTEXT_PROP_OPACITY:
+      g_value_set_double (value, gimp_context_get_opacity (context));
+      break;
+    case GIMP_CONTEXT_PROP_PAINT_MODE:
+      g_value_set_enum (value, gimp_context_get_paint_mode (context));
+      break;
+    case GIMP_CONTEXT_PROP_BRUSH:
+      g_value_set_object (value, gimp_context_get_brush (context));
+      break;
+    case GIMP_CONTEXT_PROP_DYNAMICS:
+      g_value_set_object (value, gimp_context_get_dynamics (context));
+      break;
+    case GIMP_CONTEXT_PROP_MYBRUSH:
+      g_value_set_object (value, gimp_context_get_mybrush (context));
+      break;
+    case GIMP_CONTEXT_PROP_PATTERN:
+      g_value_set_object (value, gimp_context_get_pattern (context));
+      break;
+    case GIMP_CONTEXT_PROP_GRADIENT:
+      g_value_set_object (value, gimp_context_get_gradient (context));
+      break;
+    case GIMP_CONTEXT_PROP_PALETTE:
+      g_value_set_object (value, gimp_context_get_palette (context));
+      break;
+    case GIMP_CONTEXT_PROP_FONT:
+      g_value_set_object (value, gimp_context_get_font (context));
+      break;
+    case GIMP_CONTEXT_PROP_TOOL_PRESET:
+      g_value_set_object (value, gimp_context_get_tool_preset (context));
+      break;
+    case GIMP_CONTEXT_PROP_BUFFER:
+      g_value_set_object (value, gimp_context_get_buffer (context));
+      break;
+    case GIMP_CONTEXT_PROP_IMAGEFILE:
+      g_value_set_object (value, gimp_context_get_imagefile (context));
+      break;
+    case GIMP_CONTEXT_PROP_TEMPLATE:
+      g_value_set_object (value, gimp_context_get_template (context));
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static gint64
+gimp_context_get_memsize (GimpObject *object,
+                          gint64     *gui_size)
+{
+  GimpContext *context = GIMP_CONTEXT (object);
+  gint64       memsize = 0;
+
+  memsize += gimp_string_get_memsize (context->tool_name);
+  memsize += gimp_string_get_memsize (context->paint_name);
+  memsize += gimp_string_get_memsize (context->brush_name);
+  memsize += gimp_string_get_memsize (context->dynamics_name);
+  memsize += gimp_string_get_memsize (context->mybrush_name);
+  memsize += gimp_string_get_memsize (context->pattern_name);
+  memsize += gimp_string_get_memsize (context->palette_name);
+  memsize += gimp_string_get_memsize (context->font_name);
+  memsize += gimp_string_get_memsize (context->tool_preset_name);
+  memsize += gimp_string_get_memsize (context->buffer_name);
+  memsize += gimp_string_get_memsize (context->imagefile_name);
+  memsize += gimp_string_get_memsize (context->template_name);
+
+  return memsize + GIMP_OBJECT_CLASS (parent_class)->get_memsize (object,
+                                                                  gui_size);
+}
+
+static gboolean
+gimp_context_serialize (GimpConfig       *config,
+                        GimpConfigWriter *writer,
+                        gpointer          data)
+{
+  return gimp_config_serialize_changed_properties (config, writer);
+}
+
+static gboolean
+gimp_context_deserialize (GimpConfig *config,
+                          GScanner   *scanner,
+                          gint        nest_level,
+                          gpointer    data)
+{
+  GimpContext   *context        = GIMP_CONTEXT (config);
+  GimpLayerMode  old_paint_mode = context->paint_mode;
+  gboolean       success;
+
+  success = gimp_config_deserialize_properties (config, scanner, nest_level);
+
+  if (context->paint_mode != old_paint_mode)
+    {
+      if (context->paint_mode == GIMP_LAYER_MODE_OVERLAY_LEGACY)
+        g_object_set (context,
+                      "paint-mode", GIMP_LAYER_MODE_SOFTLIGHT_LEGACY,
+                      NULL);
+    }
+
+  return success;
+}
+
+static gboolean
+gimp_context_serialize_property (GimpConfig       *config,
+                                 guint             property_id,
+                                 const GValue     *value,
+                                 GParamSpec       *pspec,
+                                 GimpConfigWriter *writer)
+{
+  GimpContext *context = GIMP_CONTEXT (config);
+  GimpObject  *serialize_obj;
+
+  /*  serialize nothing if the property is not in serialize_props  */
+  if (! ((1 << property_id) & context->serialize_props))
+    return TRUE;
+
+  switch (property_id)
+    {
+    case GIMP_CONTEXT_PROP_TOOL:
+    case GIMP_CONTEXT_PROP_PAINT_INFO:
+    case GIMP_CONTEXT_PROP_BRUSH:
+    case GIMP_CONTEXT_PROP_DYNAMICS:
+    case GIMP_CONTEXT_PROP_MYBRUSH:
+    case GIMP_CONTEXT_PROP_PATTERN:
+    case GIMP_CONTEXT_PROP_GRADIENT:
+    case GIMP_CONTEXT_PROP_PALETTE:
+    case GIMP_CONTEXT_PROP_FONT:
+    case GIMP_CONTEXT_PROP_TOOL_PRESET:
+      serialize_obj = g_value_get_object (value);
+      break;
+
+    default:
+      return FALSE;
+    }
+
+  gimp_config_writer_open (writer, pspec->name);
+
+  if (serialize_obj)
+    gimp_config_writer_string (writer, gimp_object_get_name (serialize_obj));
+  else
+    gimp_config_writer_print (writer, "NULL", 4);
+
+  gimp_config_writer_close (writer);
+
+  return TRUE;
+}
+
+static gboolean
+gimp_context_deserialize_property (GimpConfig *object,
+                                   guint       property_id,
+                                   GValue     *value,
+                                   GParamSpec *pspec,
+                                   GScanner   *scanner,
+                                   GTokenType *expected)
+{
+  GimpContext   *context = GIMP_CONTEXT (object);
+  GimpContainer *container;
+  gpointer       standard;
+  gchar        **name_loc;
+  gchar         *object_name;
+
+  switch (property_id)
+    {
+    case GIMP_CONTEXT_PROP_TOOL:
+      container = context->gimp->tool_info_list;
+      standard  = gimp_tool_info_get_standard (context->gimp);
+      name_loc  = &context->tool_name;
+      break;
+
+    case GIMP_CONTEXT_PROP_PAINT_INFO:
+      container = context->gimp->paint_info_list;
+      standard  = gimp_paint_info_get_standard (context->gimp);
+      name_loc  = &context->paint_name;
+      break;
+
+    case GIMP_CONTEXT_PROP_BRUSH:
+      container = gimp_data_factory_get_container (context->gimp->brush_factory);
+      standard  = gimp_brush_get_standard (context);
+      name_loc  = &context->brush_name;
+      break;
+
+    case GIMP_CONTEXT_PROP_DYNAMICS:
+      container = gimp_data_factory_get_container (context->gimp->dynamics_factory);
+      standard  = gimp_dynamics_get_standard (context);
+      name_loc  = &context->dynamics_name;
+      break;
+
+    case GIMP_CONTEXT_PROP_MYBRUSH:
+      container = gimp_data_factory_get_container (context->gimp->mybrush_factory);
+      standard  = gimp_mybrush_get_standard (context);
+      name_loc  = &context->mybrush_name;
+      break;
+
+    case GIMP_CONTEXT_PROP_PATTERN:
+      container = gimp_data_factory_get_container (context->gimp->pattern_factory);
+      standard  = gimp_pattern_get_standard (context);
+      name_loc  = &context->pattern_name;
+      break;
+
+    case GIMP_CONTEXT_PROP_GRADIENT:
+      container = gimp_data_factory_get_container (context->gimp->gradient_factory);
+      standard  = gimp_gradient_get_standard (context);
+      name_loc  = &context->gradient_name;
+      break;
+
+    case GIMP_CONTEXT_PROP_PALETTE:
+      container = gimp_data_factory_get_container (context->gimp->palette_factory);
+      standard  = gimp_palette_get_standard (context);
+      name_loc  = &context->palette_name;
+      break;
+
+    case GIMP_CONTEXT_PROP_FONT:
+      container = gimp_data_factory_get_container (context->gimp->font_factory);
+      standard  = gimp_font_get_standard ();
+      name_loc  = &context->font_name;
+      break;
+
+    case GIMP_CONTEXT_PROP_TOOL_PRESET:
+      container = gimp_data_factory_get_container (context->gimp->tool_preset_factory);
+      standard  = NULL;
+      name_loc  = &context->tool_preset_name;
+      break;
+
+    default:
+      return FALSE;
+    }
+
+  if (gimp_scanner_parse_identifier (scanner, "NULL"))
+    {
+      g_value_set_object (value, NULL);
+    }
+  else if (gimp_scanner_parse_string (scanner, &object_name))
+    {
+      GimpObject *deserialize_obj;
+
+      if (! object_name)
+        object_name = g_strdup ("");
+
+      deserialize_obj = gimp_container_get_child_by_name (container,
+                                                          object_name);
+
+      if (! deserialize_obj)
+        {
+          g_value_set_object (value, standard);
+
+          g_free (*name_loc);
+          *name_loc = g_strdup (object_name);
+        }
+      else
+        {
+          g_value_set_object (value, deserialize_obj);
+        }
+
+      g_free (object_name);
+    }
+  else
+    {
+      *expected = G_TOKEN_STRING;
+    }
+
+  return TRUE;
+}
+
+static GimpConfig *
+gimp_context_duplicate (GimpConfig *config)
+{
+  GimpContext *context = GIMP_CONTEXT (config);
+  GimpContext *new;
+
+  new = GIMP_CONTEXT (parent_config_iface->duplicate (config));
+
+  COPY_NAME (context, new, tool_name);
+  COPY_NAME (context, new, paint_name);
+  COPY_NAME (context, new, brush_name);
+  COPY_NAME (context, new, dynamics_name);
+  COPY_NAME (context, new, mybrush_name);
+  COPY_NAME (context, new, pattern_name);
+  COPY_NAME (context, new, gradient_name);
+  COPY_NAME (context, new, palette_name);
+  COPY_NAME (context, new, font_name);
+  COPY_NAME (context, new, tool_preset_name);
+  COPY_NAME (context, new, buffer_name);
+  COPY_NAME (context, new, imagefile_name);
+  COPY_NAME (context, new, template_name);
+
+  return GIMP_CONFIG (new);
+}
+
+static gboolean
+gimp_context_copy (GimpConfig  *src,
+                   GimpConfig  *dest,
+                   GParamFlags  flags)
+{
+  GimpContext *src_context  = GIMP_CONTEXT (src);
+  GimpContext *dest_context = GIMP_CONTEXT (dest);
+  gboolean     success      = parent_config_iface->copy (src, dest, flags);
+
+  COPY_NAME (src_context, dest_context, tool_name);
+  COPY_NAME (src_context, dest_context, paint_name);
+  COPY_NAME (src_context, dest_context, brush_name);
+  COPY_NAME (src_context, dest_context, dynamics_name);
+  COPY_NAME (src_context, dest_context, mybrush_name);
+  COPY_NAME (src_context, dest_context, pattern_name);
+  COPY_NAME (src_context, dest_context, gradient_name);
+  COPY_NAME (src_context, dest_context, palette_name);
+  COPY_NAME (src_context, dest_context, font_name);
+  COPY_NAME (src_context, dest_context, tool_preset_name);
+  COPY_NAME (src_context, dest_context, buffer_name);
+  COPY_NAME (src_context, dest_context, imagefile_name);
+  COPY_NAME (src_context, dest_context, template_name);
+
+  return success;
+}
+
+
+/*****************************************************************************/
+/*  public functions  ********************************************************/
+
+GimpContext *
+gimp_context_new (Gimp        *gimp,
+                  const gchar *name,
+                  GimpContext *template)
+{
+  GimpContext *context;
+
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+  g_return_val_if_fail (name != NULL, NULL);
+  g_return_val_if_fail (template == NULL || GIMP_IS_CONTEXT (template), NULL);
+
+  context = g_object_new (GIMP_TYPE_CONTEXT,
+                          "name", name,
+                          "gimp", gimp,
+                          NULL);
+
+  if (template)
+    {
+      context->defined_props = template->defined_props;
+
+      gimp_context_copy_properties (template, context,
+                                    GIMP_CONTEXT_PROP_MASK_ALL);
+    }
+
+  return context;
+}
+
+GimpContext *
+gimp_context_get_parent (GimpContext *context)
+{
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+
+  return context->parent;
+}
+
+static void
+gimp_context_parent_notify (GimpContext *parent,
+                            GParamSpec  *pspec,
+                            GimpContext *context)
+{
+  if (pspec->owner_type == GIMP_TYPE_CONTEXT)
+    {
+      GimpContextPropType prop = pspec->param_id;
+
+      /*  copy from parent if the changed property is undefined;
+       *  ignore properties that are not context properties, for
+       *  example notifications on the context's "gimp" property
+       */
+      if ((prop >= GIMP_CONTEXT_PROP_FIRST) &&
+          (prop <= GIMP_CONTEXT_PROP_LAST)  &&
+          ! ((1 << prop) & context->defined_props))
+        {
+          gimp_context_copy_property (parent, context, prop);
+        }
+    }
+}
+
+void
+gimp_context_set_parent (GimpContext *context,
+                         GimpContext *parent)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+  g_return_if_fail (parent == NULL || GIMP_IS_CONTEXT (parent));
+  g_return_if_fail (parent == NULL || parent->parent != context);
+  g_return_if_fail (context != parent);
+
+  if (context->parent == parent)
+    return;
+
+  if (context->parent)
+    {
+      g_signal_handlers_disconnect_by_func (context->parent,
+                                            gimp_context_parent_notify,
+                                            context);
+
+      g_object_remove_weak_pointer (G_OBJECT (context->parent),
+                                    (gpointer) &context->parent);
+    }
+
+  context->parent = parent;
+
+  if (parent)
+    {
+      g_object_add_weak_pointer (G_OBJECT (context->parent),
+                                 (gpointer) &context->parent);
+
+      /*  copy all undefined properties from the new parent  */
+      gimp_context_copy_properties (parent, context,
+                                    ~context->defined_props &
+                                    GIMP_CONTEXT_PROP_MASK_ALL);
+
+      g_signal_connect_object (parent, "notify",
+                               G_CALLBACK (gimp_context_parent_notify),
+                               context,
+                               0);
+    }
+}
+
+
+/*  define / undefinine context properties  */
+
+void
+gimp_context_define_property (GimpContext         *context,
+                              GimpContextPropType  prop,
+                              gboolean             defined)
+{
+  GimpContextPropMask mask;
+
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+  g_return_if_fail ((prop >= GIMP_CONTEXT_PROP_FIRST) &&
+                    (prop <= GIMP_CONTEXT_PROP_LAST));
+
+  mask = (1 << prop);
+
+  if (defined)
+    {
+      if (! (context->defined_props & mask))
+        {
+          context->defined_props |= mask;
+        }
+    }
+  else
+    {
+      if (context->defined_props & mask)
+        {
+          context->defined_props &= ~mask;
+
+          if (context->parent)
+            gimp_context_copy_property (context->parent, context, prop);
+        }
+    }
+}
+
+gboolean
+gimp_context_property_defined (GimpContext         *context,
+                               GimpContextPropType  prop)
+{
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), FALSE);
+
+  return (context->defined_props & (1 << prop)) ? TRUE : FALSE;
+}
+
+void
+gimp_context_define_properties (GimpContext         *context,
+                                GimpContextPropMask  prop_mask,
+                                gboolean             defined)
+{
+  GimpContextPropType prop;
+
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  for (prop = GIMP_CONTEXT_PROP_FIRST; prop <= GIMP_CONTEXT_PROP_LAST; prop++)
+    if ((1 << prop) & prop_mask)
+      gimp_context_define_property (context, prop, defined);
+}
+
+
+/*  specify which context properties will be serialized  */
+
+void
+gimp_context_set_serialize_properties (GimpContext         *context,
+                                       GimpContextPropMask  props_mask)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  context->serialize_props = props_mask;
+}
+
+GimpContextPropMask
+gimp_context_get_serialize_properties (GimpContext *context)
+{
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), 0);
+
+  return context->serialize_props;
+}
+
+
+/*  copying context properties  */
+
+void
+gimp_context_copy_property (GimpContext         *src,
+                            GimpContext         *dest,
+                            GimpContextPropType  prop)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (src));
+  g_return_if_fail (GIMP_IS_CONTEXT (dest));
+  g_return_if_fail ((prop >= GIMP_CONTEXT_PROP_FIRST) &&
+                    (prop <= GIMP_CONTEXT_PROP_LAST));
+
+  switch (prop)
+    {
+    case GIMP_CONTEXT_PROP_IMAGE:
+      gimp_context_real_set_image (dest, src->image);
+      break;
+
+    case GIMP_CONTEXT_PROP_DISPLAY:
+      gimp_context_real_set_display (dest, src->display);
+      break;
+
+    case GIMP_CONTEXT_PROP_TOOL:
+      gimp_context_real_set_tool (dest, src->tool_info);
+      COPY_NAME (src, dest, tool_name);
+      break;
+
+    case GIMP_CONTEXT_PROP_PAINT_INFO:
+      gimp_context_real_set_paint_info (dest, src->paint_info);
+      COPY_NAME (src, dest, paint_name);
+      break;
+
+    case GIMP_CONTEXT_PROP_FOREGROUND:
+      gimp_context_real_set_foreground (dest, &src->foreground);
+      break;
+
+    case GIMP_CONTEXT_PROP_BACKGROUND:
+      gimp_context_real_set_background (dest, &src->background);
+      break;
+
+    case GIMP_CONTEXT_PROP_OPACITY:
+      gimp_context_real_set_opacity (dest, src->opacity);
+      break;
+
+    case GIMP_CONTEXT_PROP_PAINT_MODE:
+      gimp_context_real_set_paint_mode (dest, src->paint_mode);
+      break;
+
+    case GIMP_CONTEXT_PROP_BRUSH:
+      gimp_context_real_set_brush (dest, src->brush);
+      COPY_NAME (src, dest, brush_name);
+      break;
+
+    case GIMP_CONTEXT_PROP_DYNAMICS:
+      gimp_context_real_set_dynamics (dest, src->dynamics);
+      COPY_NAME (src, dest, dynamics_name);
+      break;
+
+    case GIMP_CONTEXT_PROP_MYBRUSH:
+      gimp_context_real_set_mybrush (dest, src->mybrush);
+      COPY_NAME (src, dest, mybrush_name);
+      break;
+
+    case GIMP_CONTEXT_PROP_PATTERN:
+      gimp_context_real_set_pattern (dest, src->pattern);
+      COPY_NAME (src, dest, pattern_name);
+      break;
+
+    case GIMP_CONTEXT_PROP_GRADIENT:
+      gimp_context_real_set_gradient (dest, src->gradient);
+      COPY_NAME (src, dest, gradient_name);
+      break;
+
+    case GIMP_CONTEXT_PROP_PALETTE:
+      gimp_context_real_set_palette (dest, src->palette);
+      COPY_NAME (src, dest, palette_name);
+      break;
+
+    case GIMP_CONTEXT_PROP_FONT:
+      gimp_context_real_set_font (dest, src->font);
+      COPY_NAME (src, dest, font_name);
+      break;
+
+    case GIMP_CONTEXT_PROP_TOOL_PRESET:
+      gimp_context_real_set_tool_preset (dest, src->tool_preset);
+      COPY_NAME (src, dest, tool_preset_name);
+      break;
+
+    case GIMP_CONTEXT_PROP_BUFFER:
+      gimp_context_real_set_buffer (dest, src->buffer);
+      COPY_NAME (src, dest, buffer_name);
+      break;
+
+    case GIMP_CONTEXT_PROP_IMAGEFILE:
+      gimp_context_real_set_imagefile (dest, src->imagefile);
+      COPY_NAME (src, dest, imagefile_name);
+      break;
+
+    case GIMP_CONTEXT_PROP_TEMPLATE:
+      gimp_context_real_set_template (dest, src->template);
+      COPY_NAME (src, dest, template_name);
+      break;
+
+    default:
+      break;
+    }
+}
+
+void
+gimp_context_copy_properties (GimpContext         *src,
+                              GimpContext         *dest,
+                              GimpContextPropMask  prop_mask)
+{
+  GimpContextPropType prop;
+
+  g_return_if_fail (GIMP_IS_CONTEXT (src));
+  g_return_if_fail (GIMP_IS_CONTEXT (dest));
+
+  for (prop = GIMP_CONTEXT_PROP_FIRST; prop <= GIMP_CONTEXT_PROP_LAST; prop++)
+    if ((1 << prop) & prop_mask)
+      gimp_context_copy_property (src, dest, prop);
+}
+
+
+/*  attribute access functions  */
+
+/*****************************************************************************/
+/*  manipulate by GType  *****************************************************/
+
+GimpContextPropType
+gimp_context_type_to_property (GType type)
+{
+  GimpContextPropType prop;
+
+  for (prop = GIMP_CONTEXT_PROP_FIRST; prop <= GIMP_CONTEXT_PROP_LAST; prop++)
+    {
+      if (g_type_is_a (type, gimp_context_prop_types[prop]))
+        return prop;
+    }
+
+  return -1;
+}
+
+const gchar *
+gimp_context_type_to_prop_name (GType type)
+{
+  GimpContextPropType prop;
+
+  for (prop = GIMP_CONTEXT_PROP_FIRST; prop <= GIMP_CONTEXT_PROP_LAST; prop++)
+    {
+      if (g_type_is_a (type, gimp_context_prop_types[prop]))
+        return gimp_context_prop_names[prop];
+    }
+
+  return NULL;
+}
+
+const gchar *
+gimp_context_type_to_signal_name (GType type)
+{
+  GimpContextPropType prop;
+
+  for (prop = GIMP_CONTEXT_PROP_FIRST; prop <= GIMP_CONTEXT_PROP_LAST; prop++)
+    {
+      if (g_type_is_a (type, gimp_context_prop_types[prop]))
+        return g_signal_name (gimp_context_signals[prop]);
+    }
+
+  return NULL;
+}
+
+GimpObject *
+gimp_context_get_by_type (GimpContext *context,
+                          GType        type)
+{
+  GimpContextPropType  prop;
+  GimpObject          *object = NULL;
+
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+
+  prop = gimp_context_type_to_property (type);
+
+  g_return_val_if_fail (prop != -1, NULL);
+
+  g_object_get (context,
+                gimp_context_prop_names[prop], &object,
+                NULL);
+
+  /*  g_object_get() refs the object, this function however is a getter,
+   *  which usually doesn't ref it's return value
+   */
+  if (object)
+    g_object_unref (object);
+
+  return object;
+}
+
+void
+gimp_context_set_by_type (GimpContext *context,
+                          GType        type,
+                          GimpObject  *object)
+{
+  GimpContextPropType  prop;
+  GParamSpec          *pspec;
+  GValue               value = G_VALUE_INIT;
+
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+  g_return_if_fail (object == NULL || G_IS_OBJECT (object));
+
+  prop = gimp_context_type_to_property (type);
+
+  g_return_if_fail (prop != -1);
+
+  pspec = g_object_class_find_property (G_OBJECT_GET_CLASS (context),
+                                        gimp_context_prop_names[prop]);
+
+  g_return_if_fail (pspec != NULL);
+
+  g_value_init (&value, pspec->value_type);
+  g_value_set_object (&value, object);
+
+  /*  we use gimp_context_set_property() (which in turn only calls
+   *  gimp_context_set_foo() functions) instead of the much more obvious
+   *  g_object_set(); this avoids g_object_freeze_notify()/thaw_notify()
+   *  around the g_object_set() and makes GimpContext callbacks being
+   *  called in a much more predictable order. See bug #731279.
+   */
+  gimp_context_set_property (G_OBJECT (context),
+                             pspec->param_id,
+                             (const GValue *) &value,
+                             pspec);
+
+  g_value_unset (&value);
+}
+
+void
+gimp_context_changed_by_type (GimpContext *context,
+                              GType        type)
+{
+  GimpContextPropType  prop;
+  GimpObject          *object;
+
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  prop = gimp_context_type_to_property (type);
+
+  g_return_if_fail (prop != -1);
+
+  object = gimp_context_get_by_type (context, type);
+
+  g_signal_emit (context,
+                 gimp_context_signals[prop], 0,
+                 object);
+}
+
+
+/*****************************************************************************/
+/*  image  *******************************************************************/
+
+GimpImage *
+gimp_context_get_image (GimpContext *context)
+{
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+
+  return context->image;
+}
+
+void
+gimp_context_set_image (GimpContext *context,
+                        GimpImage   *image)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+  g_return_if_fail (image == NULL || GIMP_IS_IMAGE (image));
+
+  context_find_defined (context, GIMP_CONTEXT_PROP_IMAGE);
+
+  gimp_context_real_set_image (context, image);
+}
+
+void
+gimp_context_image_changed (GimpContext *context)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  g_signal_emit (context,
+                 gimp_context_signals[IMAGE_CHANGED], 0,
+                 context->image);
+}
+
+static void
+gimp_context_image_removed (GimpContainer *container,
+                            GimpImage     *image,
+                            GimpContext   *context)
+{
+  if (context->image == image)
+    gimp_context_real_set_image (context, NULL);
+}
+
+static void
+gimp_context_real_set_image (GimpContext *context,
+                             GimpImage   *image)
+{
+  if (context->image == image)
+    return;
+
+  context->image = image;
+
+  g_object_notify (G_OBJECT (context), "image");
+  gimp_context_image_changed (context);
+}
+
+
+/*****************************************************************************/
+/*  display  *****************************************************************/
+
+gpointer
+gimp_context_get_display (GimpContext *context)
+{
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+
+  return context->display;
+}
+
+void
+gimp_context_set_display (GimpContext *context,
+                          gpointer     display)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+  g_return_if_fail (display == NULL || GIMP_IS_OBJECT (display));
+
+  context_find_defined (context, GIMP_CONTEXT_PROP_DISPLAY);
+
+  gimp_context_real_set_display (context, display);
+}
+
+void
+gimp_context_display_changed (GimpContext *context)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  g_signal_emit (context,
+                 gimp_context_signals[DISPLAY_CHANGED], 0,
+                 context->display);
+}
+
+static void
+gimp_context_display_removed (GimpContainer *container,
+                              gpointer       display,
+                              GimpContext   *context)
+{
+  if (context->display == display)
+    gimp_context_real_set_display (context, NULL);
+}
+
+static void
+gimp_context_real_set_display (GimpContext *context,
+                               gpointer     display)
+{
+  GimpObject *old_display;
+
+  if (context->display == display)
+    {
+      /*  make sure that setting a display *always* sets the image
+       *  to that display's image, even if the display already
+       *  matches
+       */
+      if (display)
+        {
+          GimpImage *image;
+
+          g_object_get (display, "image", &image, NULL);
+
+          gimp_context_real_set_image (context, image);
+
+          if (image)
+            g_object_unref (image);
+        }
+
+      return;
+    }
+
+  old_display = context->display;
+
+  context->display = display;
+
+  if (context->display)
+    {
+      GimpImage *image;
+
+      g_object_get (display, "image", &image, NULL);
+
+      gimp_context_real_set_image (context, image);
+
+      if (image)
+        g_object_unref (image);
+    }
+  else if (old_display)
+    {
+      gimp_context_real_set_image (context, NULL);
+    }
+
+  g_object_notify (G_OBJECT (context), "display");
+  gimp_context_display_changed (context);
+}
+
+
+/*****************************************************************************/
+/*  tool  ********************************************************************/
+
+GimpToolInfo *
+gimp_context_get_tool (GimpContext *context)
+{
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+
+  return context->tool_info;
+}
+
+void
+gimp_context_set_tool (GimpContext  *context,
+                       GimpToolInfo *tool_info)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+  g_return_if_fail (tool_info == NULL || GIMP_IS_TOOL_INFO (tool_info));
+
+  context_find_defined (context, GIMP_CONTEXT_PROP_TOOL);
+
+  gimp_context_real_set_tool (context, tool_info);
+}
+
+void
+gimp_context_tool_changed (GimpContext *context)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  g_signal_emit (context,
+                 gimp_context_signals[TOOL_CHANGED], 0,
+                 context->tool_info);
+}
+
+static void
+gimp_context_tool_dirty (GimpToolInfo *tool_info,
+                         GimpContext  *context)
+{
+  g_free (context->tool_name);
+  context->tool_name = g_strdup (gimp_object_get_name (tool_info));
+
+  g_signal_emit (context, gimp_context_signals[PROP_NAME_CHANGED], 0,
+                 GIMP_CONTEXT_PROP_TOOL);
+}
+
+static void
+gimp_context_tool_list_thaw (GimpContainer *container,
+                             GimpContext   *context)
+{
+  GimpToolInfo *tool_info;
+
+  if (! context->tool_name)
+    context->tool_name = g_strdup ("gimp-paintbrush-tool");
+
+  tool_info = gimp_context_find_object (context, container,
+                                        context->tool_name,
+                                        gimp_tool_info_get_standard (context->gimp));
+
+  gimp_context_real_set_tool (context, tool_info);
+}
+
+static void
+gimp_context_tool_removed (GimpContainer *container,
+                           GimpToolInfo  *tool_info,
+                           GimpContext   *context)
+{
+  if (tool_info == context->tool_info)
+    {
+      g_signal_handlers_disconnect_by_func (context->tool_info,
+                                            gimp_context_tool_dirty,
+                                            context);
+      g_clear_object (&context->tool_info);
+
+      if (! gimp_container_frozen (container))
+        gimp_context_tool_list_thaw (container, context);
+    }
+}
+
+static void
+gimp_context_real_set_tool (GimpContext  *context,
+                            GimpToolInfo *tool_info)
+{
+  if (context->tool_info == tool_info)
+    return;
+
+  if (context->tool_name &&
+      tool_info != gimp_tool_info_get_standard (context->gimp))
+    {
+      g_clear_pointer (&context->tool_name, g_free);
+    }
+
+  if (context->tool_info)
+    g_signal_handlers_disconnect_by_func (context->tool_info,
+                                          gimp_context_tool_dirty,
+                                          context);
+
+  g_set_object (&context->tool_info, tool_info);
+
+  if (tool_info)
+    {
+      g_signal_connect_object (tool_info, "name-changed",
+                               G_CALLBACK (gimp_context_tool_dirty),
+                               context,
+                               0);
+
+      if (tool_info != gimp_tool_info_get_standard (context->gimp))
+        context->tool_name = g_strdup (gimp_object_get_name (tool_info));
+
+      if (tool_info->paint_info)
+        gimp_context_real_set_paint_info (context, tool_info->paint_info);
+    }
+
+  g_object_notify (G_OBJECT (context), "tool");
+  gimp_context_tool_changed (context);
+}
+
+
+/*****************************************************************************/
+/*  paint info  **************************************************************/
+
+GimpPaintInfo *
+gimp_context_get_paint_info (GimpContext *context)
+{
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+
+  return context->paint_info;
+}
+
+void
+gimp_context_set_paint_info (GimpContext   *context,
+                             GimpPaintInfo *paint_info)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+  g_return_if_fail (paint_info == NULL || GIMP_IS_PAINT_INFO (paint_info));
+
+  context_find_defined (context, GIMP_CONTEXT_PROP_PAINT_INFO);
+
+  gimp_context_real_set_paint_info (context, paint_info);
+}
+
+void
+gimp_context_paint_info_changed (GimpContext *context)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  g_signal_emit (context,
+                 gimp_context_signals[PAINT_INFO_CHANGED], 0,
+                 context->paint_info);
+}
+
+static void
+gimp_context_paint_info_dirty (GimpPaintInfo *paint_info,
+                               GimpContext   *context)
+{
+  g_free (context->paint_name);
+  context->paint_name = g_strdup (gimp_object_get_name (paint_info));
+
+  g_signal_emit (context, gimp_context_signals[PROP_NAME_CHANGED], 0,
+                 GIMP_CONTEXT_PROP_PAINT_INFO);
+}
+
+/*  the global paint info list is there again after refresh  */
+static void
+gimp_context_paint_info_list_thaw (GimpContainer *container,
+                                   GimpContext   *context)
+{
+  GimpPaintInfo *paint_info;
+
+  if (! context->paint_name)
+    context->paint_name = g_strdup ("gimp-paintbrush");
+
+  paint_info = gimp_context_find_object (context, container,
+                                         context->paint_name,
+                                         gimp_paint_info_get_standard (context->gimp));
+
+  gimp_context_real_set_paint_info (context, paint_info);
+}
+
+static void
+gimp_context_paint_info_removed (GimpContainer *container,
+                                 GimpPaintInfo *paint_info,
+                                 GimpContext   *context)
+{
+  if (paint_info == context->paint_info)
+    {
+      g_signal_handlers_disconnect_by_func (context->paint_info,
+                                            gimp_context_paint_info_dirty,
+                                            context);
+      g_clear_object (&context->paint_info);
+
+      if (! gimp_container_frozen (container))
+        gimp_context_paint_info_list_thaw (container, context);
+    }
+}
+
+static void
+gimp_context_real_set_paint_info (GimpContext   *context,
+                                  GimpPaintInfo *paint_info)
+{
+  if (context->paint_info == paint_info)
+    return;
+
+  if (context->paint_name &&
+      paint_info != gimp_paint_info_get_standard (context->gimp))
+    {
+      g_clear_pointer (&context->paint_name, g_free);
+    }
+
+  if (context->paint_info)
+    g_signal_handlers_disconnect_by_func (context->paint_info,
+                                          gimp_context_paint_info_dirty,
+                                          context);
+
+  g_set_object (&context->paint_info, paint_info);
+
+  if (paint_info)
+    {
+      g_signal_connect_object (paint_info, "name-changed",
+                               G_CALLBACK (gimp_context_paint_info_dirty),
+                               context,
+                               0);
+
+      if (paint_info != gimp_paint_info_get_standard (context->gimp))
+        context->paint_name = g_strdup (gimp_object_get_name (paint_info));
+    }
+
+  g_object_notify (G_OBJECT (context), "paint-info");
+  gimp_context_paint_info_changed (context);
+}
+
+
+/*****************************************************************************/
+/*  foreground color  ********************************************************/
+
+void
+gimp_context_get_foreground (GimpContext *context,
+                             GimpRGB     *color)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+  g_return_if_fail (color != NULL);
+
+  *color = context->foreground;
+}
+
+void
+gimp_context_set_foreground (GimpContext   *context,
+                             const GimpRGB *color)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+  g_return_if_fail (color != NULL);
+
+  context_find_defined (context, GIMP_CONTEXT_PROP_FOREGROUND);
+
+  gimp_context_real_set_foreground (context, color);
+}
+
+void
+gimp_context_foreground_changed (GimpContext *context)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  g_signal_emit (context,
+                 gimp_context_signals[FOREGROUND_CHANGED], 0,
+                 &context->foreground);
+}
+
+static void
+gimp_context_real_set_foreground (GimpContext   *context,
+                                  const GimpRGB *color)
+{
+  if (gimp_rgba_distance (&context->foreground, color) < RGBA_EPSILON)
+    return;
+
+  context->foreground = *color;
+  gimp_rgb_set_alpha (&context->foreground, GIMP_OPACITY_OPAQUE);
+
+  g_object_notify (G_OBJECT (context), "foreground");
+  gimp_context_foreground_changed (context);
+}
+
+
+/*****************************************************************************/
+/*  background color  ********************************************************/
+
+void
+gimp_context_get_background (GimpContext *context,
+                             GimpRGB     *color)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  g_return_if_fail (color != NULL);
+
+  *color = context->background;
+}
+
+void
+gimp_context_set_background (GimpContext   *context,
+                             const GimpRGB *color)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+  g_return_if_fail (color != NULL);
+
+  context_find_defined (context, GIMP_CONTEXT_PROP_BACKGROUND);
+
+  gimp_context_real_set_background (context, color);
+}
+
+void
+gimp_context_background_changed (GimpContext *context)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  g_signal_emit (context,
+                 gimp_context_signals[BACKGROUND_CHANGED], 0,
+                 &context->background);
+}
+
+static void
+gimp_context_real_set_background (GimpContext   *context,
+                                  const GimpRGB *color)
+{
+  if (gimp_rgba_distance (&context->background, color) < RGBA_EPSILON)
+    return;
+
+  context->background = *color;
+  gimp_rgb_set_alpha (&context->background, GIMP_OPACITY_OPAQUE);
+
+  g_object_notify (G_OBJECT (context), "background");
+  gimp_context_background_changed (context);
+}
+
+
+/*****************************************************************************/
+/*  color utility functions  *************************************************/
+
+void
+gimp_context_set_default_colors (GimpContext *context)
+{
+  GimpContext *bg_context;
+  GimpRGB      fg;
+  GimpRGB      bg;
+
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  bg_context = context;
+
+  context_find_defined (context, GIMP_CONTEXT_PROP_FOREGROUND);
+  context_find_defined (bg_context, GIMP_CONTEXT_PROP_BACKGROUND);
+
+  gimp_rgba_set (&fg, 0.0, 0.0, 0.0, GIMP_OPACITY_OPAQUE);
+  gimp_rgba_set (&bg, 1.0, 1.0, 1.0, GIMP_OPACITY_OPAQUE);
+
+  gimp_context_real_set_foreground (context, &fg);
+  gimp_context_real_set_background (bg_context, &bg);
+}
+
+void
+gimp_context_swap_colors (GimpContext *context)
+{
+  GimpContext *bg_context;
+  GimpRGB      fg;
+  GimpRGB      bg;
+
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  bg_context = context;
+
+  context_find_defined (context, GIMP_CONTEXT_PROP_FOREGROUND);
+  context_find_defined (bg_context, GIMP_CONTEXT_PROP_BACKGROUND);
+
+  gimp_context_get_foreground (context, &fg);
+  gimp_context_get_background (bg_context, &bg);
+
+  gimp_context_real_set_foreground (context, &bg);
+  gimp_context_real_set_background (bg_context, &fg);
+}
+
+
+/*****************************************************************************/
+/*  opacity  *****************************************************************/
+
+gdouble
+gimp_context_get_opacity (GimpContext *context)
+{
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), GIMP_OPACITY_OPAQUE);
+
+  return context->opacity;
+}
+
+void
+gimp_context_set_opacity (GimpContext *context,
+                          gdouble      opacity)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  context_find_defined (context, GIMP_CONTEXT_PROP_OPACITY);
+
+  gimp_context_real_set_opacity (context, opacity);
+}
+
+void
+gimp_context_opacity_changed (GimpContext *context)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  g_signal_emit (context,
+                 gimp_context_signals[OPACITY_CHANGED], 0,
+                 context->opacity);
+}
+
+static void
+gimp_context_real_set_opacity (GimpContext *context,
+                               gdouble      opacity)
+{
+  if (context->opacity == opacity)
+    return;
+
+  context->opacity = opacity;
+
+  g_object_notify (G_OBJECT (context), "opacity");
+  gimp_context_opacity_changed (context);
+}
+
+
+/*****************************************************************************/
+/*  paint mode  **************************************************************/
+
+GimpLayerMode
+gimp_context_get_paint_mode (GimpContext *context)
+{
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), GIMP_LAYER_MODE_NORMAL);
+
+  return context->paint_mode;
+}
+
+void
+gimp_context_set_paint_mode (GimpContext   *context,
+                             GimpLayerMode  paint_mode)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  context_find_defined (context, GIMP_CONTEXT_PROP_PAINT_MODE);
+
+  gimp_context_real_set_paint_mode (context, paint_mode);
+}
+
+void
+gimp_context_paint_mode_changed (GimpContext *context)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  g_signal_emit (context,
+                 gimp_context_signals[PAINT_MODE_CHANGED], 0,
+                 context->paint_mode);
+}
+
+static void
+gimp_context_real_set_paint_mode (GimpContext   *context,
+                                  GimpLayerMode  paint_mode)
+{
+  if (context->paint_mode == paint_mode)
+    return;
+
+  context->paint_mode = paint_mode;
+
+  g_object_notify (G_OBJECT (context), "paint-mode");
+  gimp_context_paint_mode_changed (context);
+}
+
+
+/*****************************************************************************/
+/*  brush  *******************************************************************/
+
+GimpBrush *
+gimp_context_get_brush (GimpContext *context)
+{
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+
+  return context->brush;
+}
+
+void
+gimp_context_set_brush (GimpContext *context,
+                        GimpBrush   *brush)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+  g_return_if_fail (brush == NULL || GIMP_IS_BRUSH (brush));
+
+  context_find_defined (context, GIMP_CONTEXT_PROP_BRUSH);
+
+  gimp_context_real_set_brush (context, brush);
+}
+
+void
+gimp_context_brush_changed (GimpContext *context)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  g_signal_emit (context,
+                 gimp_context_signals[BRUSH_CHANGED], 0,
+                 context->brush);
+}
+
+static void
+gimp_context_brush_dirty (GimpBrush   *brush,
+                          GimpContext *context)
+{
+  g_free (context->brush_name);
+  context->brush_name = g_strdup (gimp_object_get_name (brush));
+
+  g_signal_emit (context, gimp_context_signals[PROP_NAME_CHANGED], 0,
+                 GIMP_CONTEXT_PROP_BRUSH);
+}
+
+static void
+gimp_context_brush_list_thaw (GimpContainer *container,
+                              GimpContext   *context)
+{
+  GimpBrush *brush;
+
+  if (! context->brush_name)
+    context->brush_name = g_strdup (context->gimp->config->default_brush);
+
+  brush = gimp_context_find_object (context, container,
+                                    context->brush_name,
+                                    gimp_brush_get_standard (context));
+
+  gimp_context_real_set_brush (context, brush);
+}
+
+/*  the active brush disappeared  */
+static void
+gimp_context_brush_removed (GimpContainer *container,
+                            GimpBrush     *brush,
+                            GimpContext   *context)
+{
+  if (brush == context->brush)
+    {
+      g_signal_handlers_disconnect_by_func (context->brush,
+                                            gimp_context_brush_dirty,
+                                            context);
+      g_clear_object (&context->brush);
+
+      if (! gimp_container_frozen (container))
+        gimp_context_brush_list_thaw (container, context);
+    }
+}
+
+static void
+gimp_context_real_set_brush (GimpContext *context,
+                             GimpBrush   *brush)
+{
+  if (context->brush == brush)
+    return;
+
+  if (context->brush_name &&
+      brush != GIMP_BRUSH (gimp_brush_get_standard (context)))
+    {
+      g_clear_pointer (&context->brush_name, g_free);
+    }
+
+  if (context->brush)
+    g_signal_handlers_disconnect_by_func (context->brush,
+                                          gimp_context_brush_dirty,
+                                          context);
+
+  g_set_object (&context->brush, brush);
+
+  if (brush)
+    {
+      g_signal_connect_object (brush, "name-changed",
+                               G_CALLBACK (gimp_context_brush_dirty),
+                               context,
+                               0);
+
+      if (brush != GIMP_BRUSH (gimp_brush_get_standard (context)))
+        context->brush_name = g_strdup (gimp_object_get_name (brush));
+    }
+
+  g_object_notify (G_OBJECT (context), "brush");
+  gimp_context_brush_changed (context);
+}
+
+
+/*****************************************************************************/
+/*  dynamics *****************************************************************/
+
+GimpDynamics *
+gimp_context_get_dynamics (GimpContext *context)
+{
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+
+  return context->dynamics;
+}
+
+void
+gimp_context_set_dynamics (GimpContext  *context,
+                           GimpDynamics *dynamics)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+  g_return_if_fail (dynamics == NULL || GIMP_IS_DYNAMICS (dynamics));
+
+  context_find_defined (context, GIMP_CONTEXT_PROP_DYNAMICS);
+
+  gimp_context_real_set_dynamics (context, dynamics);
+}
+
+void
+gimp_context_dynamics_changed (GimpContext *context)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  g_signal_emit (context,
+                 gimp_context_signals[DYNAMICS_CHANGED], 0,
+                 context->dynamics);
+}
+
+static void
+gimp_context_dynamics_dirty (GimpDynamics *dynamics,
+                             GimpContext  *context)
+{
+  g_free (context->dynamics_name);
+  context->dynamics_name = g_strdup (gimp_object_get_name (dynamics));
+
+  g_signal_emit (context, gimp_context_signals[PROP_NAME_CHANGED], 0,
+                 GIMP_CONTEXT_PROP_DYNAMICS);
+}
+
+static void
+gimp_context_dynamics_removed (GimpContainer *container,
+                               GimpDynamics  *dynamics,
+                               GimpContext   *context)
+{
+  if (dynamics == context->dynamics)
+    {
+      g_signal_handlers_disconnect_by_func (context->dynamics,
+                                            gimp_context_dynamics_dirty,
+                                            context);
+      g_clear_object (&context->dynamics);
+
+      if (! gimp_container_frozen (container))
+        gimp_context_dynamics_list_thaw (container, context);
+    }
+}
+
+static void
+gimp_context_dynamics_list_thaw (GimpContainer *container,
+                                 GimpContext   *context)
+{
+  GimpDynamics *dynamics;
+
+  if (! context->dynamics_name)
+    context->dynamics_name = g_strdup (context->gimp->config->default_dynamics);
+
+  dynamics = gimp_context_find_object (context, container,
+                                       context->dynamics_name,
+                                       gimp_dynamics_get_standard (context));
+
+  gimp_context_real_set_dynamics (context, dynamics);
+}
+
+static void
+gimp_context_real_set_dynamics (GimpContext  *context,
+                                GimpDynamics *dynamics)
+{
+  if (context->dynamics == dynamics)
+    return;
+
+  if (context->dynamics_name &&
+      dynamics != GIMP_DYNAMICS (gimp_dynamics_get_standard (context)))
+    {
+      g_clear_pointer (&context->dynamics_name, g_free);
+    }
+
+  if (context->dynamics)
+    g_signal_handlers_disconnect_by_func (context->dynamics,
+                                          gimp_context_dynamics_dirty,
+                                          context);
+
+  g_set_object (&context->dynamics, dynamics);
+
+  if (dynamics)
+    {
+      g_signal_connect_object (dynamics, "name-changed",
+                               G_CALLBACK (gimp_context_dynamics_dirty),
+                               context,
+                               0);
+
+      if (dynamics != GIMP_DYNAMICS (gimp_dynamics_get_standard (context)))
+        context->dynamics_name = g_strdup (gimp_object_get_name (dynamics));
+    }
+
+  g_object_notify (G_OBJECT (context), "dynamics");
+  gimp_context_dynamics_changed (context);
+}
+
+
+/*****************************************************************************/
+/*  mybrush  *****************************************************************/
+
+GimpMybrush *
+gimp_context_get_mybrush (GimpContext *context)
+{
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+
+  return context->mybrush;
+}
+
+void
+gimp_context_set_mybrush (GimpContext *context,
+                          GimpMybrush *brush)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+  g_return_if_fail (brush == NULL || GIMP_IS_MYBRUSH (brush));
+
+  context_find_defined (context, GIMP_CONTEXT_PROP_MYBRUSH);
+
+  gimp_context_real_set_mybrush (context, brush);
+}
+
+void
+gimp_context_mybrush_changed (GimpContext *context)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  g_signal_emit (context,
+                 gimp_context_signals[MYBRUSH_CHANGED], 0,
+                 context->mybrush);
+}
+
+static void
+gimp_context_mybrush_dirty (GimpMybrush *brush,
+                            GimpContext *context)
+{
+  g_free (context->mybrush_name);
+  context->mybrush_name = g_strdup (gimp_object_get_name (brush));
+
+  g_signal_emit (context, gimp_context_signals[PROP_NAME_CHANGED], 0,
+                 GIMP_CONTEXT_PROP_MYBRUSH);
+}
+
+static void
+gimp_context_mybrush_list_thaw (GimpContainer *container,
+                                GimpContext   *context)
+{
+  GimpMybrush *brush;
+
+  if (! context->mybrush_name)
+    context->mybrush_name = g_strdup (context->gimp->config->default_mypaint_brush);
+
+  brush = gimp_context_find_object (context, container,
+                                    context->mybrush_name,
+                                    gimp_mybrush_get_standard (context));
+
+  gimp_context_real_set_mybrush (context, brush);
+}
+
+static void
+gimp_context_mybrush_removed (GimpContainer *container,
+                              GimpMybrush   *brush,
+                              GimpContext   *context)
+{
+  if (brush == context->mybrush)
+    {
+      g_signal_handlers_disconnect_by_func (context->mybrush,
+                                            gimp_context_mybrush_dirty,
+                                            context);
+      g_clear_object (&context->mybrush);
+
+      if (! gimp_container_frozen (container))
+        gimp_context_mybrush_list_thaw (container, context);
+    }
+}
+
+static void
+gimp_context_real_set_mybrush (GimpContext *context,
+                               GimpMybrush *brush)
+{
+  if (context->mybrush == brush)
+    return;
+
+  if (context->mybrush_name &&
+      brush != GIMP_MYBRUSH (gimp_mybrush_get_standard (context)))
+    {
+      g_clear_pointer (&context->mybrush_name, g_free);
+    }
+
+  if (context->mybrush)
+    g_signal_handlers_disconnect_by_func (context->mybrush,
+                                          gimp_context_mybrush_dirty,
+                                          context);
+
+  g_set_object (&context->mybrush, brush);
+
+  if (brush)
+    {
+      g_signal_connect_object (brush, "name-changed",
+                               G_CALLBACK (gimp_context_mybrush_dirty),
+                               context,
+                               0);
+
+      if (brush != GIMP_MYBRUSH (gimp_mybrush_get_standard (context)))
+        context->mybrush_name = g_strdup (gimp_object_get_name (brush));
+    }
+
+  g_object_notify (G_OBJECT (context), "mybrush");
+  gimp_context_mybrush_changed (context);
+}
+
+
+/*****************************************************************************/
+/*  pattern  *****************************************************************/
+
+GimpPattern *
+gimp_context_get_pattern (GimpContext *context)
+{
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+
+  return context->pattern;
+}
+
+void
+gimp_context_set_pattern (GimpContext *context,
+                          GimpPattern *pattern)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+  g_return_if_fail (pattern == NULL || GIMP_IS_PATTERN (pattern));
+
+  context_find_defined (context, GIMP_CONTEXT_PROP_PATTERN);
+
+  gimp_context_real_set_pattern (context, pattern);
+}
+
+void
+gimp_context_pattern_changed (GimpContext *context)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  g_signal_emit (context,
+                 gimp_context_signals[PATTERN_CHANGED], 0,
+                 context->pattern);
+}
+
+static void
+gimp_context_pattern_dirty (GimpPattern *pattern,
+                            GimpContext *context)
+{
+  g_free (context->pattern_name);
+  context->pattern_name = g_strdup (gimp_object_get_name (pattern));
+
+  g_signal_emit (context, gimp_context_signals[PROP_NAME_CHANGED], 0,
+                 GIMP_CONTEXT_PROP_PATTERN);
+}
+
+static void
+gimp_context_pattern_list_thaw (GimpContainer *container,
+                                GimpContext   *context)
+{
+  GimpPattern *pattern;
+
+  if (! context->pattern_name)
+    context->pattern_name = g_strdup (context->gimp->config->default_pattern);
+
+  pattern = gimp_context_find_object (context, container,
+                                      context->pattern_name,
+                                      gimp_pattern_get_standard (context));
+
+  gimp_context_real_set_pattern (context, pattern);
+}
+
+static void
+gimp_context_pattern_removed (GimpContainer *container,
+                              GimpPattern   *pattern,
+                              GimpContext   *context)
+{
+  if (pattern == context->pattern)
+    {
+      g_signal_handlers_disconnect_by_func (context->pattern,
+                                            gimp_context_pattern_dirty,
+                                            context);
+      g_clear_object (&context->pattern);
+
+      if (! gimp_container_frozen (container))
+        gimp_context_pattern_list_thaw (container, context);
+    }
+}
+
+static void
+gimp_context_real_set_pattern (GimpContext *context,
+                               GimpPattern *pattern)
+{
+  if (context->pattern == pattern)
+    return;
+
+  if (context->pattern_name &&
+      pattern != GIMP_PATTERN (gimp_pattern_get_standard (context)))
+    {
+      g_clear_pointer (&context->pattern_name, g_free);
+    }
+
+  if (context->pattern)
+    g_signal_handlers_disconnect_by_func (context->pattern,
+                                          gimp_context_pattern_dirty,
+                                          context);
+
+  g_set_object (&context->pattern, pattern);
+
+  if (pattern)
+    {
+      g_signal_connect_object (pattern, "name-changed",
+                               G_CALLBACK (gimp_context_pattern_dirty),
+                               context,
+                               0);
+
+      if (pattern != GIMP_PATTERN (gimp_pattern_get_standard (context)))
+        context->pattern_name = g_strdup (gimp_object_get_name (pattern));
+    }
+
+  g_object_notify (G_OBJECT (context), "pattern");
+  gimp_context_pattern_changed (context);
+}
+
+
+/*****************************************************************************/
+/*  gradient  ****************************************************************/
+
+GimpGradient *
+gimp_context_get_gradient (GimpContext *context)
+{
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+
+  return context->gradient;
+}
+
+void
+gimp_context_set_gradient (GimpContext  *context,
+                           GimpGradient *gradient)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+  g_return_if_fail (gradient == NULL || GIMP_IS_GRADIENT (gradient));
+
+  context_find_defined (context, GIMP_CONTEXT_PROP_GRADIENT);
+
+  gimp_context_real_set_gradient (context, gradient);
+}
+
+void
+gimp_context_gradient_changed (GimpContext *context)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  g_signal_emit (context,
+                 gimp_context_signals[GRADIENT_CHANGED], 0,
+                 context->gradient);
+}
+
+static void
+gimp_context_gradient_dirty (GimpGradient *gradient,
+                             GimpContext  *context)
+{
+  g_free (context->gradient_name);
+  context->gradient_name = g_strdup (gimp_object_get_name (gradient));
+
+  g_signal_emit (context, gimp_context_signals[PROP_NAME_CHANGED], 0,
+                 GIMP_CONTEXT_PROP_GRADIENT);
+}
+
+static void
+gimp_context_gradient_list_thaw (GimpContainer *container,
+                                 GimpContext   *context)
+{
+  GimpGradient *gradient;
+
+  if (! context->gradient_name)
+    context->gradient_name = g_strdup (context->gimp->config->default_gradient);
+
+  gradient = gimp_context_find_object (context, container,
+                                       context->gradient_name,
+                                       gimp_gradient_get_standard (context));
+
+  gimp_context_real_set_gradient (context, gradient);
+}
+
+static void
+gimp_context_gradient_removed (GimpContainer *container,
+                               GimpGradient  *gradient,
+                               GimpContext   *context)
+{
+  if (gradient == context->gradient)
+    {
+      g_signal_handlers_disconnect_by_func (context->gradient,
+                                            gimp_context_gradient_dirty,
+                                            context);
+      g_clear_object (&context->gradient);
+
+      if (! gimp_container_frozen (container))
+        gimp_context_gradient_list_thaw (container, context);
+    }
+}
+
+static void
+gimp_context_real_set_gradient (GimpContext  *context,
+                                GimpGradient *gradient)
+{
+  if (context->gradient == gradient)
+    return;
+
+  if (context->gradient_name &&
+      gradient != GIMP_GRADIENT (gimp_gradient_get_standard (context)))
+    {
+      g_clear_pointer (&context->gradient_name, g_free);
+    }
+
+  if (context->gradient)
+    g_signal_handlers_disconnect_by_func (context->gradient,
+                                          gimp_context_gradient_dirty,
+                                          context);
+
+  g_set_object (&context->gradient, gradient);
+
+  if (gradient)
+    {
+      g_signal_connect_object (gradient, "name-changed",
+                               G_CALLBACK (gimp_context_gradient_dirty),
+                               context,
+                               0);
+
+      if (gradient != GIMP_GRADIENT (gimp_gradient_get_standard (context)))
+        context->gradient_name = g_strdup (gimp_object_get_name (gradient));
+    }
+
+  g_object_notify (G_OBJECT (context), "gradient");
+  gimp_context_gradient_changed (context);
+}
+
+
+/*****************************************************************************/
+/*  palette  *****************************************************************/
+
+GimpPalette *
+gimp_context_get_palette (GimpContext *context)
+{
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+
+  return context->palette;
+}
+
+void
+gimp_context_set_palette (GimpContext *context,
+                          GimpPalette *palette)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+  g_return_if_fail (palette == NULL || GIMP_IS_PALETTE (palette));
+
+  context_find_defined (context, GIMP_CONTEXT_PROP_PALETTE);
+
+  gimp_context_real_set_palette (context, palette);
+}
+
+void
+gimp_context_palette_changed (GimpContext *context)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  g_signal_emit (context,
+                 gimp_context_signals[PALETTE_CHANGED], 0,
+                 context->palette);
+}
+
+static void
+gimp_context_palette_dirty (GimpPalette *palette,
+                            GimpContext *context)
+{
+  g_free (context->palette_name);
+  context->palette_name = g_strdup (gimp_object_get_name (palette));
+
+  g_signal_emit (context, gimp_context_signals[PROP_NAME_CHANGED], 0,
+                 GIMP_CONTEXT_PROP_PALETTE);
+}
+
+static void
+gimp_context_palette_list_thaw (GimpContainer *container,
+                                GimpContext   *context)
+{
+  GimpPalette *palette;
+
+  if (! context->palette_name)
+    context->palette_name = g_strdup (context->gimp->config->default_palette);
+
+  palette = gimp_context_find_object (context, container,
+                                      context->palette_name,
+                                      gimp_palette_get_standard (context));
+
+  gimp_context_real_set_palette (context, palette);
+}
+
+static void
+gimp_context_palette_removed (GimpContainer *container,
+                              GimpPalette   *palette,
+                              GimpContext   *context)
+{
+  if (palette == context->palette)
+    {
+      g_signal_handlers_disconnect_by_func (context->palette,
+                                            gimp_context_palette_dirty,
+                                            context);
+      g_clear_object (&context->palette);
+
+      if (! gimp_container_frozen (container))
+        gimp_context_palette_list_thaw (container, context);
+    }
+}
+
+static void
+gimp_context_real_set_palette (GimpContext *context,
+                               GimpPalette *palette)
+{
+  if (context->palette == palette)
+    return;
+
+  if (context->palette_name &&
+      palette != GIMP_PALETTE (gimp_palette_get_standard (context)))
+    {
+      g_clear_pointer (&context->palette_name, g_free);
+    }
+
+  if (context->palette)
+    g_signal_handlers_disconnect_by_func (context->palette,
+                                          gimp_context_palette_dirty,
+                                          context);
+
+  g_set_object (&context->palette, palette);
+
+  if (palette)
+    {
+      g_signal_connect_object (palette, "name-changed",
+                               G_CALLBACK (gimp_context_palette_dirty),
+                               context,
+                               0);
+
+      if (palette != GIMP_PALETTE (gimp_palette_get_standard (context)))
+        context->palette_name = g_strdup (gimp_object_get_name (palette));
+    }
+
+  g_object_notify (G_OBJECT (context), "palette");
+  gimp_context_palette_changed (context);
+}
+
+
+/*****************************************************************************/
+/*  font     *****************************************************************/
+
+GimpFont *
+gimp_context_get_font (GimpContext *context)
+{
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+
+  return context->font;
+}
+
+void
+gimp_context_set_font (GimpContext *context,
+                       GimpFont    *font)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+  g_return_if_fail (font == NULL || GIMP_IS_FONT (font));
+
+  context_find_defined (context, GIMP_CONTEXT_PROP_FONT);
+
+  gimp_context_real_set_font (context, font);
+}
+
+const gchar *
+gimp_context_get_font_name (GimpContext *context)
+{
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+
+  return context->font_name;
+}
+
+void
+gimp_context_set_font_name (GimpContext *context,
+                            const gchar *name)
+{
+  GimpContainer *container;
+  GimpObject    *font;
+
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  container = gimp_data_factory_get_container (context->gimp->font_factory);
+  font      = gimp_container_get_child_by_name (container, name);
+
+  if (font)
+    {
+      gimp_context_set_font (context, GIMP_FONT (font));
+    }
+  else
+    {
+      /* No font with this name exists, use the standard font, but
+       * keep the intended name around
+       */
+      gimp_context_set_font (context, GIMP_FONT (gimp_font_get_standard ()));
+
+      g_free (context->font_name);
+      context->font_name = g_strdup (name);
+    }
+}
+
+void
+gimp_context_font_changed (GimpContext *context)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  g_signal_emit (context,
+                 gimp_context_signals[FONT_CHANGED], 0,
+                 context->font);
+}
+
+static void
+gimp_context_font_dirty (GimpFont    *font,
+                         GimpContext *context)
+{
+  g_free (context->font_name);
+  context->font_name = g_strdup (gimp_object_get_name (font));
+
+  g_signal_emit (context, gimp_context_signals[PROP_NAME_CHANGED], 0,
+                 GIMP_CONTEXT_PROP_FONT);
+}
+
+static void
+gimp_context_font_list_thaw (GimpContainer *container,
+                             GimpContext   *context)
+{
+  GimpFont *font;
+
+  if (! context->font_name)
+    context->font_name = g_strdup (context->gimp->config->default_font);
+
+  font = gimp_context_find_object (context, container,
+                                   context->font_name,
+                                   gimp_font_get_standard ());
+
+  gimp_context_real_set_font (context, font);
+}
+
+static void
+gimp_context_font_removed (GimpContainer *container,
+                           GimpFont      *font,
+                           GimpContext   *context)
+{
+  if (font == context->font)
+    {
+      g_signal_handlers_disconnect_by_func (context->font,
+                                            gimp_context_font_dirty,
+                                            context);
+      g_clear_object (&context->font);
+
+      if (! gimp_container_frozen (container))
+        gimp_context_font_list_thaw (container, context);
+    }
+}
+
+static void
+gimp_context_real_set_font (GimpContext *context,
+                            GimpFont    *font)
+{
+  if (context->font == font)
+    return;
+
+  if (context->font_name &&
+      font != GIMP_FONT (gimp_font_get_standard ()))
+    {
+      g_clear_pointer (&context->font_name, g_free);
+    }
+
+  if (context->font)
+    g_signal_handlers_disconnect_by_func (context->font,
+                                          gimp_context_font_dirty,
+                                          context);
+
+  g_set_object (&context->font, font);
+
+  if (font)
+    {
+      g_signal_connect_object (font, "name-changed",
+                               G_CALLBACK (gimp_context_font_dirty),
+                               context,
+                               0);
+
+      if (font != GIMP_FONT (gimp_font_get_standard ()))
+        context->font_name = g_strdup (gimp_object_get_name (font));
+    }
+
+  g_object_notify (G_OBJECT (context), "font");
+  gimp_context_font_changed (context);
+}
+
+
+/********************************************************************************/
+/*  tool preset *****************************************************************/
+
+GimpToolPreset *
+gimp_context_get_tool_preset (GimpContext *context)
+{
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+
+  return context->tool_preset;
+}
+
+void
+gimp_context_set_tool_preset (GimpContext    *context,
+                              GimpToolPreset *tool_preset)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+  g_return_if_fail (tool_preset == NULL || GIMP_IS_TOOL_PRESET (tool_preset));
+
+  context_find_defined (context, GIMP_CONTEXT_PROP_TOOL_PRESET);
+
+  gimp_context_real_set_tool_preset (context, tool_preset);
+}
+
+void
+gimp_context_tool_preset_changed (GimpContext *context)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  g_signal_emit (context,
+                 gimp_context_signals[TOOL_PRESET_CHANGED], 0,
+                 context->tool_preset);
+}
+
+static void
+gimp_context_tool_preset_dirty (GimpToolPreset *tool_preset,
+                                GimpContext    *context)
+{
+  g_free (context->tool_preset_name);
+  context->tool_preset_name = g_strdup (gimp_object_get_name (tool_preset));
+
+  g_signal_emit (context, gimp_context_signals[PROP_NAME_CHANGED], 0,
+                 GIMP_CONTEXT_PROP_TOOL_PRESET);
+}
+
+static void
+gimp_context_tool_preset_removed (GimpContainer  *container,
+                                  GimpToolPreset *tool_preset,
+                                  GimpContext    *context)
+{
+  if (tool_preset == context->tool_preset)
+    {
+      g_signal_handlers_disconnect_by_func (context->tool_preset,
+                                            gimp_context_tool_preset_dirty,
+                                            context);
+      g_clear_object (&context->tool_preset);
+
+      if (! gimp_container_frozen (container))
+        gimp_context_tool_preset_list_thaw (container, context);
+    }
+}
+
+static void
+gimp_context_tool_preset_list_thaw (GimpContainer *container,
+                                    GimpContext   *context)
+{
+  GimpToolPreset *tool_preset;
+
+  tool_preset = gimp_context_find_object (context, container,
+                                          context->tool_preset_name,
+                                          NULL);
+
+  gimp_context_real_set_tool_preset (context, tool_preset);
+}
+
+static void
+gimp_context_real_set_tool_preset (GimpContext    *context,
+                                   GimpToolPreset *tool_preset)
+{
+  if (context->tool_preset == tool_preset)
+    return;
+
+  if (context->tool_preset_name)
+    {
+      g_clear_pointer (&context->tool_preset_name, g_free);
+    }
+
+  if (context->tool_preset)
+    g_signal_handlers_disconnect_by_func (context->tool_preset,
+                                          gimp_context_tool_preset_dirty,
+                                          context);
+
+  g_set_object (&context->tool_preset, tool_preset);
+
+  if (tool_preset)
+    {
+      g_signal_connect_object (tool_preset, "name-changed",
+                               G_CALLBACK (gimp_context_tool_preset_dirty),
+                               context,
+                               0);
+
+      context->tool_preset_name = g_strdup (gimp_object_get_name (tool_preset));
+    }
+
+  g_object_notify (G_OBJECT (context), "tool-preset");
+  gimp_context_tool_preset_changed (context);
+}
+
+
+/*****************************************************************************/
+/*  buffer  ******************************************************************/
+
+GimpBuffer *
+gimp_context_get_buffer (GimpContext *context)
+{
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+
+  return context->buffer;
+}
+
+void
+gimp_context_set_buffer (GimpContext *context,
+                         GimpBuffer *buffer)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+  g_return_if_fail (buffer == NULL || GIMP_IS_BUFFER (buffer));
+
+  context_find_defined (context, GIMP_CONTEXT_PROP_BUFFER);
+
+  gimp_context_real_set_buffer (context, buffer);
+}
+
+void
+gimp_context_buffer_changed (GimpContext *context)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  g_signal_emit (context,
+                 gimp_context_signals[BUFFER_CHANGED], 0,
+                 context->buffer);
+}
+
+static void
+gimp_context_buffer_dirty (GimpBuffer  *buffer,
+                           GimpContext *context)
+{
+  g_free (context->buffer_name);
+  context->buffer_name = g_strdup (gimp_object_get_name (buffer));
+
+  g_signal_emit (context, gimp_context_signals[PROP_NAME_CHANGED], 0,
+                 GIMP_CONTEXT_PROP_BUFFER);
+}
+
+static void
+gimp_context_buffer_list_thaw (GimpContainer *container,
+                               GimpContext   *context)
+{
+  GimpBuffer *buffer;
+
+  buffer = gimp_context_find_object (context, container,
+                                     context->buffer_name,
+                                     NULL);
+
+  if (buffer)
+    {
+      gimp_context_real_set_buffer (context, buffer);
+    }
+  else
+    {
+      g_object_notify (G_OBJECT (context), "buffer");
+      gimp_context_buffer_changed (context);
+    }
+}
+
+static void
+gimp_context_buffer_removed (GimpContainer *container,
+                             GimpBuffer    *buffer,
+                             GimpContext   *context)
+{
+  if (buffer == context->buffer)
+    {
+      g_signal_handlers_disconnect_by_func (context->buffer,
+                                            gimp_context_buffer_dirty,
+                                            context);
+      g_clear_object (&context->buffer);
+
+      if (! gimp_container_frozen (container))
+        gimp_context_buffer_list_thaw (container, context);
+    }
+}
+
+static void
+gimp_context_real_set_buffer (GimpContext *context,
+                              GimpBuffer  *buffer)
+{
+  if (context->buffer == buffer)
+    return;
+
+  if (context->buffer_name)
+    {
+      g_clear_pointer (&context->buffer_name, g_free);
+    }
+
+  if (context->buffer)
+    g_signal_handlers_disconnect_by_func (context->buffer,
+                                          gimp_context_buffer_dirty,
+                                          context);
+
+  g_set_object (&context->buffer, buffer);
+
+  if (buffer)
+    {
+      g_signal_connect_object (buffer, "name-changed",
+                               G_CALLBACK (gimp_context_buffer_dirty),
+                               context,
+                               0);
+
+      context->buffer_name = g_strdup (gimp_object_get_name (buffer));
+    }
+
+  g_object_notify (G_OBJECT (context), "buffer");
+  gimp_context_buffer_changed (context);
+}
+
+
+/*****************************************************************************/
+/*  imagefile  ***************************************************************/
+
+GimpImagefile *
+gimp_context_get_imagefile (GimpContext *context)
+{
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+
+  return context->imagefile;
+}
+
+void
+gimp_context_set_imagefile (GimpContext   *context,
+                            GimpImagefile *imagefile)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+  g_return_if_fail (imagefile == NULL || GIMP_IS_IMAGEFILE (imagefile));
+
+  context_find_defined (context, GIMP_CONTEXT_PROP_IMAGEFILE);
+
+  gimp_context_real_set_imagefile (context, imagefile);
+}
+
+void
+gimp_context_imagefile_changed (GimpContext *context)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  g_signal_emit (context,
+                 gimp_context_signals[IMAGEFILE_CHANGED], 0,
+                 context->imagefile);
+}
+
+static void
+gimp_context_imagefile_dirty (GimpImagefile *imagefile,
+                              GimpContext   *context)
+{
+  g_free (context->imagefile_name);
+  context->imagefile_name = g_strdup (gimp_object_get_name (imagefile));
+
+  g_signal_emit (context, gimp_context_signals[PROP_NAME_CHANGED], 0,
+                 GIMP_CONTEXT_PROP_IMAGEFILE);
+}
+
+static void
+gimp_context_imagefile_list_thaw (GimpContainer *container,
+                                  GimpContext   *context)
+{
+  GimpImagefile *imagefile;
+
+  imagefile = gimp_context_find_object (context, container,
+                                        context->imagefile_name,
+                                        NULL);
+
+  if (imagefile)
+    {
+      gimp_context_real_set_imagefile (context, imagefile);
+    }
+  else
+    {
+      g_object_notify (G_OBJECT (context), "imagefile");
+      gimp_context_imagefile_changed (context);
+    }
+}
+
+static void
+gimp_context_imagefile_removed (GimpContainer *container,
+                                GimpImagefile *imagefile,
+                                GimpContext   *context)
+{
+  if (imagefile == context->imagefile)
+    {
+      g_signal_handlers_disconnect_by_func (context->imagefile,
+                                            gimp_context_imagefile_dirty,
+                                            context);
+      g_clear_object (&context->imagefile);
+
+      if (! gimp_container_frozen (container))
+        gimp_context_imagefile_list_thaw (container, context);
+    }
+}
+
+static void
+gimp_context_real_set_imagefile (GimpContext   *context,
+                                 GimpImagefile *imagefile)
+{
+  if (context->imagefile == imagefile)
+    return;
+
+  if (context->imagefile_name)
+    {
+      g_clear_pointer (&context->imagefile_name, g_free);
+    }
+
+  if (context->imagefile)
+    g_signal_handlers_disconnect_by_func (context->imagefile,
+                                          gimp_context_imagefile_dirty,
+                                          context);
+
+  g_set_object (&context->imagefile, imagefile);
+
+  if (imagefile)
+    {
+      g_signal_connect_object (imagefile, "name-changed",
+                               G_CALLBACK (gimp_context_imagefile_dirty),
+                               context,
+                               0);
+
+      context->imagefile_name = g_strdup (gimp_object_get_name (imagefile));
+    }
+
+  g_object_notify (G_OBJECT (context), "imagefile");
+  gimp_context_imagefile_changed (context);
+}
+
+
+/*****************************************************************************/
+/*  template  ***************************************************************/
+
+GimpTemplate *
+gimp_context_get_template (GimpContext *context)
+{
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+
+  return context->template;
+}
+
+void
+gimp_context_set_template (GimpContext  *context,
+                           GimpTemplate *template)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+  g_return_if_fail (template == NULL || GIMP_IS_TEMPLATE (template));
+
+  context_find_defined (context, GIMP_CONTEXT_PROP_TEMPLATE);
+
+  gimp_context_real_set_template (context, template);
+}
+
+void
+gimp_context_template_changed (GimpContext *context)
+{
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  g_signal_emit (context,
+                 gimp_context_signals[TEMPLATE_CHANGED], 0,
+                 context->template);
+}
+
+static void
+gimp_context_template_dirty (GimpTemplate *template,
+                             GimpContext  *context)
+{
+  g_free (context->template_name);
+  context->template_name = g_strdup (gimp_object_get_name (template));
+
+  g_signal_emit (context, gimp_context_signals[PROP_NAME_CHANGED], 0,
+                 GIMP_CONTEXT_PROP_TEMPLATE);
+}
+
+static void
+gimp_context_template_list_thaw (GimpContainer *container,
+                                 GimpContext   *context)
+{
+  GimpTemplate *template;
+
+  template = gimp_context_find_object (context, container,
+                                       context->template_name,
+                                       NULL);
+
+  if (template)
+    {
+      gimp_context_real_set_template (context, template);
+    }
+  else
+    {
+      g_object_notify (G_OBJECT (context), "template");
+      gimp_context_template_changed (context);
+    }
+}
+
+static void
+gimp_context_template_removed (GimpContainer *container,
+                               GimpTemplate  *template,
+                               GimpContext   *context)
+{
+  if (template == context->template)
+    {
+      g_signal_handlers_disconnect_by_func (context->template,
+                                            gimp_context_template_dirty,
+                                            context);
+      g_clear_object (&context->template);
+
+      if (! gimp_container_frozen (container))
+        gimp_context_template_list_thaw (container, context);
+    }
+}
+
+static void
+gimp_context_real_set_template (GimpContext  *context,
+                                GimpTemplate *template)
+{
+  if (context->template == template)
+    return;
+
+  if (context->template_name)
+    {
+      g_clear_pointer (&context->template_name, g_free);
+    }
+
+  if (context->template)
+    g_signal_handlers_disconnect_by_func (context->template,
+                                          gimp_context_template_dirty,
+                                          context);
+
+  g_set_object (&context->template, template);
+
+  if (template)
+    {
+      g_signal_connect_object (template, "name-changed",
+                               G_CALLBACK (gimp_context_template_dirty),
+                               context,
+                               0);
+
+      context->template_name = g_strdup (gimp_object_get_name (template));
+    }
+
+  g_object_notify (G_OBJECT (context), "template");
+  gimp_context_template_changed (context);
+}
+
+
+/*****************************************************************************/
+/*  utility functions  *******************************************************/
+
+static gpointer
+gimp_context_find_object (GimpContext   *context,
+                          GimpContainer *container,
+                          const gchar   *object_name,
+                          gpointer       standard_object)
+{
+  GimpObject *object = NULL;
+
+  if (object_name)
+    object = gimp_container_get_child_by_name (container, object_name);
+
+  if (! object && ! gimp_container_is_empty (container))
+    object = gimp_container_get_child_by_index (container, 0);
+
+  if (! object)
+    object = standard_object;
+
+  return object;
+}
diff --git a/app/core/gimpcontext.h b/app/core/gimpcontext.h
new file mode 100644
index 0000000..7f15a4a
--- /dev/null
+++ b/app/core/gimpcontext.h
@@ -0,0 +1,360 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpcontext.h
+ * Copyright (C) 1999-2010 Michael Natterer
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_CONTEXT_H__
+#define __GIMP_CONTEXT_H__
+
+
+#include "gimpviewable.h"
+
+
+#define GIMP_TYPE_CONTEXT            (gimp_context_get_type ())
+#define GIMP_CONTEXT(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_CONTEXT, GimpContext))
+#define GIMP_CONTEXT_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST (klass, GIMP_TYPE_CONTEXT, GimpContextClass))
+#define GIMP_IS_CONTEXT(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_CONTEXT))
+#define GIMP_IS_CONTEXT_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_CONTEXT))
+#define GIMP_CONTEXT_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS (obj, GIMP_TYPE_CONTEXT, GimpContextClass))
+
+
+typedef struct _GimpContextClass GimpContextClass;
+
+/**
+ * GimpContext:
+ *
+ * Holds state such as the active image, active display, active brush,
+ * active foreground and background color, and so on. There can many
+ * instances of contexts. The user context is what the user sees and
+ * interacts with but there can also be contexts for docks and for
+ * plug-ins.
+ */
+struct _GimpContext
+{
+  GimpViewable          parent_instance;
+
+  Gimp                 *gimp;
+
+  GimpContext          *parent;
+
+  guint32               defined_props;
+  guint32               serialize_props;
+
+  GimpImage            *image;
+  gpointer              display;
+
+  GimpToolInfo         *tool_info;
+  gchar                *tool_name;
+
+  GimpPaintInfo        *paint_info;
+  gchar                *paint_name;
+
+  GimpRGB               foreground;
+  GimpRGB               background;
+
+  gdouble               opacity;
+  GimpLayerMode         paint_mode;
+
+  GimpBrush            *brush;
+  gchar                *brush_name;
+
+  GimpDynamics         *dynamics;
+  gchar                *dynamics_name;
+
+  GimpMybrush          *mybrush;
+  gchar                *mybrush_name;
+
+  GimpPattern          *pattern;
+  gchar                *pattern_name;
+
+  GimpGradient         *gradient;
+  gchar                *gradient_name;
+
+  GimpPalette          *palette;
+  gchar                *palette_name;
+
+  GimpFont             *font;
+  gchar                *font_name;
+
+  GimpToolPreset       *tool_preset;
+  gchar                *tool_preset_name;
+
+  GimpBuffer           *buffer;
+  gchar                *buffer_name;
+
+  GimpImagefile        *imagefile;
+  gchar                *imagefile_name;
+
+  GimpTemplate         *template;
+  gchar                *template_name;
+};
+
+struct _GimpContextClass
+{
+  GimpViewableClass  parent_class;
+
+  void (* image_changed)      (GimpContext          *context,
+                               GimpImage            *image);
+  void (* display_changed)    (GimpContext          *context,
+                               gpointer              display);
+
+  void (* tool_changed)       (GimpContext          *context,
+                               GimpToolInfo         *tool_info);
+  void (* paint_info_changed) (GimpContext          *context,
+                               GimpPaintInfo        *paint_info);
+
+  void (* foreground_changed) (GimpContext          *context,
+                               GimpRGB              *color);
+  void (* background_changed) (GimpContext          *context,
+                               GimpRGB              *color);
+  void (* opacity_changed)    (GimpContext          *context,
+                               gdouble               opacity);
+  void (* paint_mode_changed) (GimpContext          *context,
+                               GimpLayerMode         paint_mode);
+  void (* brush_changed)      (GimpContext          *context,
+                               GimpBrush            *brush);
+  void (* dynamics_changed)   (GimpContext          *context,
+                               GimpDynamics         *dynamics);
+  void (* mybrush_changed)    (GimpContext          *context,
+                               GimpMybrush          *brush);
+  void (* pattern_changed)    (GimpContext          *context,
+                               GimpPattern          *pattern);
+  void (* gradient_changed)   (GimpContext          *context,
+                               GimpGradient         *gradient);
+  void (* palette_changed)    (GimpContext          *context,
+                               GimpPalette          *palette);
+  void (* font_changed)       (GimpContext          *context,
+                               GimpFont             *font);
+  void (* tool_preset_changed)(GimpContext          *context,
+                               GimpToolPreset       *tool_preset);
+  void (* buffer_changed)     (GimpContext          *context,
+                               GimpBuffer           *buffer);
+  void (* imagefile_changed)  (GimpContext          *context,
+                               GimpImagefile        *imagefile);
+  void (* template_changed)   (GimpContext          *context,
+                               GimpTemplate         *template);
+
+  void (* prop_name_changed)  (GimpContext          *context,
+                               GimpContextPropType   prop);
+};
+
+
+GType         gimp_context_get_type          (void) G_GNUC_CONST;
+
+GimpContext * gimp_context_new               (Gimp                *gimp,
+                                              const gchar         *name,
+                                              GimpContext         *template);
+
+GimpContext * gimp_context_get_parent        (GimpContext         *context);
+void          gimp_context_set_parent        (GimpContext         *context,
+                                              GimpContext         *parent);
+
+/*  define / undefinine context properties
+ *
+ *  the value of an undefined property will be taken from the parent context.
+ */
+void          gimp_context_define_property   (GimpContext         *context,
+                                              GimpContextPropType  prop,
+                                              gboolean             defined);
+
+gboolean      gimp_context_property_defined  (GimpContext         *context,
+                                              GimpContextPropType  prop);
+
+void          gimp_context_define_properties (GimpContext         *context,
+                                              GimpContextPropMask  props_mask,
+                                              gboolean             defined);
+
+
+/*  specify which context properties will be serialized
+ */
+void   gimp_context_set_serialize_properties (GimpContext         *context,
+                                              GimpContextPropMask  props_mask);
+
+GimpContextPropMask
+       gimp_context_get_serialize_properties (GimpContext         *context);
+
+
+/*  copying context properties
+ */
+void          gimp_context_copy_property     (GimpContext         *src,
+                                              GimpContext         *dest,
+                                              GimpContextPropType  prop);
+
+void          gimp_context_copy_properties   (GimpContext         *src,
+                                              GimpContext         *dest,
+                                              GimpContextPropMask  props_mask);
+
+
+/*  manipulate by GType  */
+GimpContextPropType   gimp_context_type_to_property    (GType     type);
+const gchar         * gimp_context_type_to_prop_name   (GType     type);
+const gchar         * gimp_context_type_to_signal_name (GType     type);
+
+GimpObject     * gimp_context_get_by_type         (GimpContext     *context,
+                                                   GType            type);
+void             gimp_context_set_by_type         (GimpContext     *context,
+                                                   GType            type,
+                                                   GimpObject      *object);
+void             gimp_context_changed_by_type     (GimpContext     *context,
+                                                   GType            type);
+
+
+/*  image  */
+GimpImage      * gimp_context_get_image           (GimpContext     *context);
+void             gimp_context_set_image           (GimpContext     *context,
+                                                   GimpImage       *image);
+void             gimp_context_image_changed       (GimpContext     *context);
+
+
+/*  display  */
+gpointer         gimp_context_get_display         (GimpContext     *context);
+void             gimp_context_set_display         (GimpContext     *context,
+                                                   gpointer         display);
+void             gimp_context_display_changed     (GimpContext     *context);
+
+
+/*  tool  */
+GimpToolInfo   * gimp_context_get_tool            (GimpContext     *context);
+void             gimp_context_set_tool            (GimpContext     *context,
+                                                   GimpToolInfo    *tool_info);
+void             gimp_context_tool_changed        (GimpContext     *context);
+
+
+/*  paint info  */
+GimpPaintInfo  * gimp_context_get_paint_info      (GimpContext     *context);
+void             gimp_context_set_paint_info      (GimpContext     *context,
+                                                   GimpPaintInfo   *paint_info);
+void             gimp_context_paint_info_changed  (GimpContext     *context);
+
+
+/*  foreground color  */
+void             gimp_context_get_foreground       (GimpContext     *context,
+                                                    GimpRGB         *color);
+void             gimp_context_set_foreground       (GimpContext     *context,
+                                                    const GimpRGB   *color);
+void             gimp_context_foreground_changed   (GimpContext     *context);
+
+
+/*  background color  */
+void             gimp_context_get_background       (GimpContext     *context,
+                                                    GimpRGB         *color);
+void             gimp_context_set_background       (GimpContext     *context,
+                                                    const GimpRGB   *color);
+void             gimp_context_background_changed   (GimpContext     *context);
+
+
+/*  color utility functions  */
+void             gimp_context_set_default_colors  (GimpContext     *context);
+void             gimp_context_swap_colors         (GimpContext     *context);
+
+
+/*  opacity  */
+gdouble          gimp_context_get_opacity         (GimpContext     *context);
+void             gimp_context_set_opacity         (GimpContext     *context,
+                                                   gdouble          opacity);
+void             gimp_context_opacity_changed     (GimpContext     *context);
+
+
+/*  paint mode  */
+GimpLayerMode    gimp_context_get_paint_mode      (GimpContext     *context);
+void             gimp_context_set_paint_mode      (GimpContext     *context,
+                                                   GimpLayerMode    paint_mode);
+void             gimp_context_paint_mode_changed  (GimpContext     *context);
+
+
+/*  brush  */
+GimpBrush      * gimp_context_get_brush           (GimpContext     *context);
+void             gimp_context_set_brush           (GimpContext     *context,
+                                                   GimpBrush       *brush);
+void             gimp_context_brush_changed       (GimpContext     *context);
+
+
+/*  dynamics  */
+GimpDynamics   * gimp_context_get_dynamics        (GimpContext     *context);
+void             gimp_context_set_dynamics        (GimpContext     *context,
+                                                   GimpDynamics    *dynamics);
+void             gimp_context_dynamics_changed    (GimpContext     *context);
+
+
+/*  mybrush  */
+GimpMybrush    * gimp_context_get_mybrush         (GimpContext     *context);
+void             gimp_context_set_mybrush         (GimpContext     *context,
+                                                   GimpMybrush     *brush);
+void             gimp_context_mybrush_changed     (GimpContext     *context);
+
+
+/*  pattern  */
+GimpPattern    * gimp_context_get_pattern         (GimpContext     *context);
+void             gimp_context_set_pattern         (GimpContext     *context,
+                                                   GimpPattern     *pattern);
+void             gimp_context_pattern_changed     (GimpContext     *context);
+
+
+/*  gradient  */
+GimpGradient   * gimp_context_get_gradient        (GimpContext     *context);
+void             gimp_context_set_gradient        (GimpContext     *context,
+                                                   GimpGradient    *gradient);
+void             gimp_context_gradient_changed    (GimpContext     *context);
+
+
+/*  palette  */
+GimpPalette    * gimp_context_get_palette         (GimpContext     *context);
+void             gimp_context_set_palette         (GimpContext     *context,
+                                                   GimpPalette     *palette);
+void             gimp_context_palette_changed     (GimpContext     *context);
+
+
+/*  font  */
+GimpFont       * gimp_context_get_font            (GimpContext     *context);
+void             gimp_context_set_font            (GimpContext     *context,
+                                                   GimpFont        *font);
+const gchar    * gimp_context_get_font_name       (GimpContext     *context);
+void             gimp_context_set_font_name       (GimpContext     *context,
+                                                   const gchar     *name);
+void             gimp_context_font_changed        (GimpContext     *context);
+
+
+/*  tool_preset  */
+GimpToolPreset * gimp_context_get_tool_preset     (GimpContext     *context);
+void             gimp_context_set_tool_preset     (GimpContext     *context,
+                                                   GimpToolPreset  *tool_preset);
+void             gimp_context_tool_preset_changed (GimpContext     *context);
+
+
+/*  buffer  */
+GimpBuffer     * gimp_context_get_buffer          (GimpContext     *context);
+void             gimp_context_set_buffer          (GimpContext     *context,
+                                                   GimpBuffer      *palette);
+void             gimp_context_buffer_changed      (GimpContext     *context);
+
+
+/*  imagefile  */
+GimpImagefile  * gimp_context_get_imagefile       (GimpContext     *context);
+void             gimp_context_set_imagefile       (GimpContext     *context,
+                                                   GimpImagefile   *imagefile);
+void             gimp_context_imagefile_changed   (GimpContext     *context);
+
+
+/*  template  */
+GimpTemplate   * gimp_context_get_template        (GimpContext     *context);
+void             gimp_context_set_template        (GimpContext     *context,
+                                                   GimpTemplate    *template);
+void             gimp_context_template_changed    (GimpContext     *context);
+
+
+#endif /* __GIMP_CONTEXT_H__ */
diff --git a/app/core/gimpcoords-interpolate.c b/app/core/gimpcoords-interpolate.c
new file mode 100644
index 0000000..f667e57
--- /dev/null
+++ b/app/core/gimpcoords-interpolate.c
@@ -0,0 +1,371 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpcoords-interpolate.c
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <glib-object.h>
+
+#include "libgimpmath/gimpmath.h"
+
+#include "core-types.h"
+
+#include "gimpcoords.h"
+#include "gimpcoords-interpolate.h"
+
+
+/* Local helper functions declarations*/
+static void     gimp_coords_interpolate_bezier_internal (const GimpCoords  bezier_pt[4],
+                                                         const gdouble     start_t,
+                                                         const gdouble     end_t,
+                                                         const gdouble     precision,
+                                                         GArray           *ret_coords,
+                                                         GArray           *ret_params,
+                                                         gint              depth);
+static gdouble  gimp_coords_get_catmull_spline_point    (const gdouble     t,
+                                                         const gdouble     p0,
+                                                         const gdouble     p1,
+                                                         const gdouble     p2,
+                                                         const gdouble     p3);
+
+/* Functions for bezier subdivision */
+
+void
+gimp_coords_interpolate_bezier (const GimpCoords  bezier_pt[4],
+                                const gdouble     precision,
+                                GArray           *ret_coords,
+                                GArray           *ret_params)
+{
+  g_return_if_fail (bezier_pt != NULL);
+  g_return_if_fail (precision > 0.0);
+  g_return_if_fail (ret_coords != NULL);
+
+  gimp_coords_interpolate_bezier_internal (bezier_pt,
+                                           0.0, 1.0,
+                                           precision,
+                                           ret_coords, ret_params, 10);
+}
+
+/* Recursive subdivision helper function */
+static void
+gimp_coords_interpolate_bezier_internal (const GimpCoords  bezier_pt[4],
+                                         const gdouble     start_t,
+                                         const gdouble     end_t,
+                                         const gdouble     precision,
+                                         GArray           *ret_coords,
+                                         GArray           *ret_params,
+                                         gint              depth)
+{
+  /*
+   * bezier_pt has to contain four GimpCoords with the four control points
+   * of the bezier segment. We subdivide it at the parameter 0.5.
+   */
+
+  GimpCoords subdivided[8];
+  gdouble    middle_t = (start_t + end_t) / 2;
+
+  subdivided[0] = bezier_pt[0];
+  subdivided[6] = bezier_pt[3];
+
+  /* if (!depth) g_printerr ("Hit recursion depth limit!\n"); */
+
+  gimp_coords_average (&bezier_pt[0],  &bezier_pt[1],  &subdivided[1]);
+  gimp_coords_average (&bezier_pt[1],  &bezier_pt[2],  &subdivided[7]);
+  gimp_coords_average (&bezier_pt[2],  &bezier_pt[3],  &subdivided[5]);
+
+  gimp_coords_average (&subdivided[1], &subdivided[7], &subdivided[2]);
+  gimp_coords_average (&subdivided[7], &subdivided[5], &subdivided[4]);
+  gimp_coords_average (&subdivided[2], &subdivided[4], &subdivided[3]);
+
+  /*
+   * We now have the coordinates of the two bezier segments in
+   * subdivided [0-3] and subdivided [3-6]
+   */
+
+  /*
+   * Here we need to check, if we have sufficiently subdivided, i.e.
+   * if the stroke is sufficiently close to a straight line.
+   */
+
+  if (! depth ||
+      gimp_coords_bezier_is_straight (subdivided, precision)) /* 1st half */
+    {
+      g_array_append_vals (ret_coords, subdivided, 3);
+
+      if (ret_params)
+        {
+          gdouble params[3];
+
+          params[0] = start_t;
+          params[1] = (2 * start_t + middle_t) / 3;
+          params[2] = (start_t + 2 * middle_t) / 3;
+
+          g_array_append_vals (ret_params, params, 3);
+        }
+    }
+  else
+    {
+      gimp_coords_interpolate_bezier_internal (subdivided,
+                                               start_t, (start_t + end_t) / 2,
+                                               precision,
+                                               ret_coords, ret_params,
+                                               depth - 1);
+    }
+
+  if (! depth ||
+      gimp_coords_bezier_is_straight (subdivided + 3, precision)) /* 2nd half */
+    {
+      g_array_append_vals (ret_coords, subdivided + 3, 3);
+
+      if (ret_params)
+        {
+          gdouble params[3];
+
+          params[0] = middle_t;
+          params[1] = (2 * middle_t + end_t) / 3;
+          params[2] = (middle_t + 2 * end_t) / 3;
+
+          g_array_append_vals (ret_params, params, 3);
+        }
+    }
+  else
+    {
+      gimp_coords_interpolate_bezier_internal (subdivided + 3,
+                                               (start_t + end_t) / 2, end_t,
+                                               precision,
+                                               ret_coords, ret_params,
+                                               depth - 1);
+    }
+}
+
+
+/*
+ * Returns the position and/or velocity of a Bezier curve at time 't'.
+ */
+
+void
+gimp_coords_interpolate_bezier_at (const GimpCoords  bezier_pt[4],
+                                   gdouble           t,
+                                   GimpCoords       *position,
+                                   GimpCoords       *velocity)
+{
+  gdouble u = 1.0 - t;
+
+  g_return_if_fail (bezier_pt != NULL);
+
+  if (position)
+    {
+      GimpCoords a;
+      GimpCoords b;
+
+      gimp_coords_mix (      u * u * u, &bezier_pt[0],
+                       3.0 * u * u * t, &bezier_pt[1],
+                                        &a);
+      gimp_coords_mix (3.0 * u * t * t, &bezier_pt[2],
+                             t * t * t, &bezier_pt[3],
+                                        &b);
+
+      gimp_coords_add (&a, &b, position);
+    }
+
+  if (velocity)
+    {
+      GimpCoords a;
+      GimpCoords b;
+
+      gimp_coords_mix (-3.0 * u * u,             &bezier_pt[0],
+                        3.0 * (u - 2.0 * t) * u, &bezier_pt[1],
+                                                 &a);
+      gimp_coords_mix (-3.0 * (t - 2.0 * u) * t, &bezier_pt[2],
+                        3.0 * t * t,             &bezier_pt[3],
+                                                 &b);
+
+      gimp_coords_add (&a, &b, velocity);
+    }
+}
+
+/*
+ * a helper function that determines if a bezier segment is "straight
+ * enough" to be approximated by a line.
+ *
+ * To be more exact, it also checks for the control points to be distributed
+ * evenly along the line. This makes it easier to reconstruct parameters for
+ * a given point along the segment.
+ *
+ * Needs four GimpCoords in an array.
+ */
+
+gboolean
+gimp_coords_bezier_is_straight (const GimpCoords bezier_pt[4],
+                                gdouble          precision)
+{
+  GimpCoords pt1, pt2;
+
+  g_return_val_if_fail (bezier_pt != NULL, FALSE);
+  g_return_val_if_fail (precision > 0.0, FALSE);
+
+  /* calculate the "ideal" positions for the control points */
+
+  gimp_coords_mix (2.0 / 3.0, &bezier_pt[0],
+                   1.0 / 3.0, &bezier_pt[3],
+                   &pt1);
+  gimp_coords_mix (1.0 / 3.0, &bezier_pt[0],
+                   2.0 / 3.0, &bezier_pt[3],
+                   &pt2);
+
+  /* calculate the deviation of the actual control points */
+
+  return (gimp_coords_manhattan_dist (&bezier_pt[1], &pt1) < precision &&
+          gimp_coords_manhattan_dist (&bezier_pt[2], &pt2) < precision);
+}
+
+
+/* Functions for catmull-rom interpolation */
+
+void
+gimp_coords_interpolate_catmull (const GimpCoords  catmull_pt[4],
+                                 gdouble           precision,
+                                 GArray           *ret_coords,
+                                 GArray           *ret_params)
+{
+  gdouble    delta_x, delta_y;
+  gdouble    distance;
+  gdouble    dir_step;
+  gdouble    delta_dir;
+  gint       num_points;
+  gint       n;
+
+  GimpCoords past_coords;
+  GimpCoords start_coords;
+  GimpCoords end_coords;
+  GimpCoords future_coords;
+
+  g_return_if_fail (catmull_pt != NULL);
+  g_return_if_fail (precision > 0.0);
+  g_return_if_fail (ret_coords != NULL);
+
+  delta_x = catmull_pt[2].x - catmull_pt[1].x;
+  delta_y = catmull_pt[2].y - catmull_pt[1].y;
+
+  /* Catmull-Rom interpolation requires 4 points.
+   * Two endpoints plus one more at each end.
+   */
+
+  past_coords   = catmull_pt[0];
+  start_coords  = catmull_pt[1];
+  end_coords    = catmull_pt[2];
+  future_coords = catmull_pt[3];
+
+  distance  = sqrt (SQR (delta_x) + SQR (delta_y));
+
+  num_points = distance / precision;
+
+  delta_dir = end_coords.direction - start_coords.direction;
+
+  if (delta_dir <= -0.5)
+    delta_dir += 1.0;
+  else if (delta_dir >= 0.5)
+    delta_dir -= 1.0;
+
+  dir_step =  delta_dir / num_points;
+
+  for (n = 1; n <= num_points; n++)
+    {
+      GimpCoords coords = past_coords; /* Make sure we carry over things
+                                        * we do not interpolate */
+      gdouble    velocity;
+      gdouble    pressure;
+      gdouble    p = (gdouble) n / num_points;
+
+      coords.x =
+        gimp_coords_get_catmull_spline_point (p,
+                                              past_coords.x,
+                                              start_coords.x,
+                                              end_coords.x,
+                                              future_coords.x);
+
+      coords.y =
+        gimp_coords_get_catmull_spline_point (p,
+                                              past_coords.y,
+                                              start_coords.y,
+                                              end_coords.y,
+                                              future_coords.y);
+
+      pressure =
+        gimp_coords_get_catmull_spline_point (p,
+                                              past_coords.pressure,
+                                              start_coords.pressure,
+                                              end_coords.pressure,
+                                              future_coords.pressure);
+      coords.pressure = CLAMP (pressure, 0.0, 1.0);
+
+      coords.xtilt =
+        gimp_coords_get_catmull_spline_point (p,
+                                              past_coords.xtilt,
+                                              start_coords.xtilt,
+                                              end_coords.xtilt,
+                                              future_coords.xtilt);
+      coords.ytilt =
+        gimp_coords_get_catmull_spline_point (p,
+                                              past_coords.ytilt,
+                                              start_coords.ytilt,
+                                              end_coords.ytilt,
+                                              future_coords.ytilt);
+
+      coords.wheel =
+        gimp_coords_get_catmull_spline_point (p,
+                                              past_coords.wheel,
+                                              start_coords.wheel,
+                                              end_coords.wheel,
+                                              future_coords.wheel);
+
+      velocity = gimp_coords_get_catmull_spline_point (p,
+                                                       past_coords.velocity,
+                                                       start_coords.velocity,
+                                                       end_coords.velocity,
+                                                       future_coords.velocity);
+      coords.velocity = CLAMP (velocity, 0.0, 1.0);
+
+      coords.direction = start_coords.direction + dir_step * n;
+
+      coords.direction = coords.direction - floor (coords.direction);
+
+      coords.xscale  = end_coords.xscale;
+      coords.yscale  = end_coords.yscale;
+      coords.angle   = end_coords.angle;
+      coords.reflect = end_coords.reflect;
+
+      g_array_append_val (ret_coords, coords);
+
+      if (ret_params)
+        g_array_append_val (ret_params, p);
+    }
+}
+
+static gdouble
+gimp_coords_get_catmull_spline_point (const gdouble t,
+                                      const gdouble p0,
+                                      const gdouble p1,
+                                      const gdouble p2,
+                                      const gdouble p3)
+{
+  return ((((-t + 2.0) * t - 1.0) * t / 2.0)        * p0 +
+          ((((3.0 * t - 5.0) * t) * t + 2.0) / 2.0) * p1 +
+          (((-3.0 * t + 4.0) * t + 1.0) * t / 2.0)  * p2 +
+          (((t - 1) * t * t) / 2.0)                 * p3);
+}
diff --git a/app/core/gimpcoords-interpolate.h b/app/core/gimpcoords-interpolate.h
new file mode 100644
index 0000000..d729cd4
--- /dev/null
+++ b/app/core/gimpcoords-interpolate.h
@@ -0,0 +1,41 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpcoords-interpolate.h
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_COORDS_INTERPOLATE_H__
+#define __GIMP_COORDS_INTERPOLATE_H__
+
+void       gimp_coords_interpolate_bezier    (const GimpCoords  bezier_pt[4],
+                                              gdouble           precision,
+                                              GArray           *ret_coords,
+                                              GArray           *ret_params);
+
+void       gimp_coords_interpolate_bezier_at (const GimpCoords  bezier_pt[4],
+                                              gdouble           t,
+                                              GimpCoords       *position,
+                                              GimpCoords       *velocity);
+
+gboolean   gimp_coords_bezier_is_straight    (const GimpCoords  bezier_pt[4],
+                                              gdouble           precision);
+
+void       gimp_coords_interpolate_catmull   (const GimpCoords  catmull_pt[4],
+                                              gdouble           precision,
+                                              GArray           *ret_coords,
+                                              GArray           *ret_params);
+
+#endif /* __GIMP_COORDS_INTERPOLATE_H__ */
diff --git a/app/core/gimpcoords.c b/app/core/gimpcoords.c
new file mode 100644
index 0000000..306f7f2
--- /dev/null
+++ b/app/core/gimpcoords.c
@@ -0,0 +1,248 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpcoords.c
+ * Copyright (C) 2002 Simon Budig  <simon@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <glib-object.h>
+
+#include "libgimpmath/gimpmath.h"
+
+#include "core-types.h"
+
+#include "gimpcoords.h"
+
+
+#define INPUT_RESOLUTION 256
+
+
+/*   amul * a + bmul * b = ret_val  */
+
+void
+gimp_coords_mix (const gdouble     amul,
+                 const GimpCoords *a,
+                 const gdouble     bmul,
+                 const GimpCoords *b,
+                 GimpCoords       *ret_val)
+{
+  if (b)
+    {
+      ret_val->x         = amul * a->x         + bmul * b->x;
+      ret_val->y         = amul * a->y         + bmul * b->y;
+      ret_val->pressure  = amul * a->pressure  + bmul * b->pressure;
+      ret_val->xtilt     = amul * a->xtilt     + bmul * b->xtilt;
+      ret_val->ytilt     = amul * a->ytilt     + bmul * b->ytilt;
+      ret_val->wheel     = amul * a->wheel     + bmul * b->wheel;
+      ret_val->velocity  = amul * a->velocity  + bmul * b->velocity;
+      ret_val->direction = amul * a->direction + bmul * b->direction;
+      ret_val->extended  = b->extended || a->extended;
+    }
+  else
+    {
+      ret_val->x         = amul * a->x;
+      ret_val->y         = amul * a->y;
+      ret_val->pressure  = amul * a->pressure;
+      ret_val->xtilt     = amul * a->xtilt;
+      ret_val->ytilt     = amul * a->ytilt;
+      ret_val->wheel     = amul * a->wheel;
+      ret_val->velocity  = amul * a->velocity;
+      ret_val->direction = amul * a->direction;
+      ret_val->extended  = a->extended;
+    }
+}
+
+
+/*    (a+b)/2 = ret_average  */
+
+void
+gimp_coords_average (const GimpCoords *a,
+                     const GimpCoords *b,
+                     GimpCoords       *ret_average)
+{
+  gimp_coords_mix (0.5, a, 0.5, b, ret_average);
+}
+
+
+/* a + b = ret_add  */
+
+void
+gimp_coords_add (const GimpCoords *a,
+                 const GimpCoords *b,
+                 GimpCoords       *ret_add)
+{
+  gimp_coords_mix (1.0, a, 1.0, b, ret_add);
+}
+
+
+/* a - b = ret_difference */
+
+void
+gimp_coords_difference (const GimpCoords *a,
+                        const GimpCoords *b,
+                        GimpCoords       *ret_difference)
+{
+  gimp_coords_mix (1.0, a, -1.0, b, ret_difference);
+}
+
+
+/* a * f = ret_product  */
+
+void
+gimp_coords_scale (const gdouble     f,
+                   const GimpCoords *a,
+                   GimpCoords       *ret_product)
+{
+  gimp_coords_mix (f, a, 0.0, NULL, ret_product);
+}
+
+
+/* local helper for measuring the scalarproduct of two gimpcoords. */
+
+gdouble
+gimp_coords_scalarprod (const GimpCoords *a,
+                        const GimpCoords *b)
+{
+  return (a->x         * b->x        +
+          a->y         * b->y        +
+          a->pressure  * b->pressure +
+          a->xtilt     * b->xtilt    +
+          a->ytilt     * b->ytilt    +
+          a->wheel     * b->wheel    +
+          a->velocity  * b->velocity +
+          a->direction * b->direction);
+}
+
+
+/*
+ * The "length" of the gimpcoord.
+ * Applies a metric that increases the weight on the
+ * pressure/xtilt/ytilt/wheel to ensure proper interpolation
+ */
+
+gdouble
+gimp_coords_length_squared (const GimpCoords *a)
+{
+  GimpCoords upscaled_a;
+
+  upscaled_a.x         = a->x;
+  upscaled_a.y         = a->y;
+  upscaled_a.pressure  = a->pressure  * INPUT_RESOLUTION;
+  upscaled_a.xtilt     = a->xtilt     * INPUT_RESOLUTION;
+  upscaled_a.ytilt     = a->ytilt     * INPUT_RESOLUTION;
+  upscaled_a.wheel     = a->wheel     * INPUT_RESOLUTION;
+  upscaled_a.velocity  = a->velocity  * INPUT_RESOLUTION;
+  upscaled_a.direction = a->direction * INPUT_RESOLUTION;
+
+  return gimp_coords_scalarprod (&upscaled_a, &upscaled_a);
+}
+
+
+gdouble
+gimp_coords_length (const GimpCoords *a)
+{
+  return sqrt (gimp_coords_length_squared (a));
+}
+
+/*
+ * Distance via manhattan metric, an upper bound for the eucledian metric.
+ * used for e.g. bezier approximation
+ */
+
+gdouble
+gimp_coords_manhattan_dist (const GimpCoords *a,
+                            const GimpCoords *b)
+{
+  gdouble dist = 0;
+
+  dist += ABS (a->pressure - b->pressure);
+  dist += ABS (a->xtilt - b->xtilt);
+  dist += ABS (a->ytilt - b->ytilt);
+  dist += ABS (a->wheel - b->wheel);
+  dist += ABS (a->velocity - b->velocity);
+  dist += ABS (a->direction - b->direction);
+
+  dist *= INPUT_RESOLUTION;
+
+  dist += ABS (a->x - b->x);
+  dist += ABS (a->y - b->y);
+
+  return dist;
+}
+
+gboolean
+gimp_coords_equal (const GimpCoords *a,
+                   const GimpCoords *b)
+{
+  return (a->x         == b->x        &&
+          a->y         == b->y        &&
+          a->pressure  == b->pressure &&
+          a->xtilt     == b->xtilt    &&
+          a->ytilt     == b->ytilt    &&
+          a->wheel     == b->wheel    &&
+          a->velocity  == b->velocity &&
+          a->direction == b->direction);
+
+  /* Extended attribute was omitted from this comparison deliberately,
+   * it describes the events origin, not its value
+   */
+}
+
+/* helper for calculating direction of two gimpcoords. */
+
+gdouble
+gimp_coords_direction (const GimpCoords *a,
+                       const GimpCoords *b)
+{
+  gdouble direction;
+  gdouble delta_x, delta_y;
+
+  delta_x = a->x - b->x;
+  delta_y = a->y - b->y;
+
+  if ((delta_x == 0) && (delta_y == 0))
+    {
+      direction = a->direction;
+    }
+  else if (delta_x == 0)
+    {
+      if (delta_y > 0)
+        direction = 0.25;
+      else
+        direction = 0.75;
+    }
+  else if (delta_y == 0)
+    {
+      if (delta_x < 0)
+        direction = 0.0;
+      else
+        direction = 0.5;
+    }
+  else
+    {
+      direction = atan ((- 1.0 * delta_y) / delta_x) / (2 * G_PI);
+
+      if (delta_x > 0.0)
+        direction = direction + 0.5;
+
+      if (direction < 0.0)
+        direction = direction + 1.0;
+    }
+
+  return direction;
+}
diff --git a/app/core/gimpcoords.h b/app/core/gimpcoords.h
new file mode 100644
index 0000000..38297f2
--- /dev/null
+++ b/app/core/gimpcoords.h
@@ -0,0 +1,57 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpcoords.h
+ * Copyright (C) 2002 Simon Budig  <simon@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_COORDS_H__
+#define __GIMP_COORDS_H__
+
+
+void     gimp_coords_mix            (const gdouble     amul,
+                                     const GimpCoords *a,
+                                     const gdouble     bmul,
+                                     const GimpCoords *b,
+                                     GimpCoords       *ret_val);
+void     gimp_coords_average        (const GimpCoords *a,
+                                     const GimpCoords *b,
+                                     GimpCoords       *ret_average);
+void     gimp_coords_add            (const GimpCoords *a,
+                                     const GimpCoords *b,
+                                     GimpCoords       *ret_add);
+void     gimp_coords_difference     (const GimpCoords *a,
+                                     const GimpCoords *b,
+                                     GimpCoords       *difference);
+void     gimp_coords_scale          (const gdouble     f,
+                                     const GimpCoords *a,
+                                     GimpCoords       *ret_product);
+
+gdouble  gimp_coords_scalarprod     (const GimpCoords *a,
+                                     const GimpCoords *b);
+gdouble  gimp_coords_length         (const GimpCoords *a);
+gdouble  gimp_coords_length_squared (const GimpCoords *a);
+gdouble  gimp_coords_manhattan_dist (const GimpCoords *a,
+                                     const GimpCoords *b);
+
+gboolean gimp_coords_equal          (const GimpCoords *a,
+                                     const GimpCoords *b);
+
+gdouble  gimp_coords_direction      (const GimpCoords *a,
+                                     const GimpCoords *b);
+
+
+#endif /* __GIMP_COORDS_H__ */
diff --git a/app/core/gimpcurve-load.c b/app/core/gimpcurve-load.c
new file mode 100644
index 0000000..9397d4a
--- /dev/null
+++ b/app/core/gimpcurve-load.c
@@ -0,0 +1,54 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpconfig/gimpconfig.h"
+
+#include "core-types.h"
+
+#include "gimpcurve.h"
+#include "gimpcurve-load.h"
+
+
+GList *
+gimp_curve_load (GFile         *file,
+                 GInputStream  *input,
+                 GError       **error)
+{
+  GimpCurve *curve;
+
+  g_return_val_if_fail (G_IS_FILE (file), NULL);
+  g_return_val_if_fail (G_IS_INPUT_STREAM (input), NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, NULL);
+
+  curve = g_object_new (GIMP_TYPE_CURVE, NULL);
+
+  if (gimp_config_deserialize_stream (GIMP_CONFIG (curve),
+                                      input,
+                                      NULL, error))
+    {
+      return g_list_prepend (NULL, curve);
+    }
+
+  g_object_unref (curve);
+
+  return NULL;
+}
diff --git a/app/core/gimpcurve-load.h b/app/core/gimpcurve-load.h
new file mode 100644
index 0000000..fc7ffa3
--- /dev/null
+++ b/app/core/gimpcurve-load.h
@@ -0,0 +1,30 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_CURVE_LOAD_H__
+#define __GIMP_CURVE_LOAD_H__
+
+
+#define GIMP_CURVE_FILE_EXTENSION ".curve"
+
+
+GList * gimp_curve_load (GFile         *file,
+                         GInputStream  *input,
+                         GError       **error);
+
+
+#endif /* __GIMP_CURVE_LOAD_H__ */
diff --git a/app/core/gimpcurve-map.c b/app/core/gimpcurve-map.c
new file mode 100644
index 0000000..bd39b27
--- /dev/null
+++ b/app/core/gimpcurve-map.c
@@ -0,0 +1,253 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpmath/gimpmath.h"
+
+#include "core-types.h"
+
+#include "gimpcurve.h"
+#include "gimpcurve-map.h"
+
+
+#if defined (HAVE_ISFINITE)
+#define FINITE(x) isfinite(x)
+#elif defined (HAVE_FINITE)
+#define FINITE(x) finite(x)
+#elif defined (G_OS_WIN32)
+#define FINITE(x) _finite(x)
+#else
+#error "no FINITE() implementation available?!"
+#endif
+
+
+enum
+{
+  CURVE_NONE   = 0,
+  CURVE_COLORS = 1 << 0,
+  CURVE_RED    = 1 << 1,
+  CURVE_GREEN  = 1 << 2,
+  CURVE_BLUE   = 1 << 3,
+  CURVE_ALPHA  = 1 << 4
+};
+
+static guint           gimp_curve_get_apply_mask   (GimpCurve *curve_colors,
+                                                    GimpCurve *curve_red,
+                                                    GimpCurve *curve_green,
+                                                    GimpCurve *curve_blue,
+                                                    GimpCurve *curve_alpha);
+static inline gdouble  gimp_curve_map_value_inline (GimpCurve *curve,
+                                                    gdouble    value);
+
+
+gdouble
+gimp_curve_map_value (GimpCurve *curve,
+                      gdouble    value)
+{
+  g_return_val_if_fail (GIMP_IS_CURVE (curve), 0.0);
+
+  return gimp_curve_map_value_inline (curve, value);
+}
+
+void
+gimp_curve_map_pixels (GimpCurve *curve_colors,
+                       GimpCurve *curve_red,
+                       GimpCurve *curve_green,
+                       GimpCurve *curve_blue,
+                       GimpCurve *curve_alpha,
+                       gfloat    *src,
+                       gfloat    *dest,
+                       glong      samples)
+{
+  g_return_if_fail (GIMP_IS_CURVE (curve_colors));
+  g_return_if_fail (GIMP_IS_CURVE (curve_red));
+  g_return_if_fail (GIMP_IS_CURVE (curve_green));
+  g_return_if_fail (GIMP_IS_CURVE (curve_blue));
+  g_return_if_fail (GIMP_IS_CURVE (curve_alpha));
+
+  switch (gimp_curve_get_apply_mask (curve_colors,
+                                     curve_red,
+                                     curve_green,
+                                     curve_blue,
+                                     curve_alpha))
+    {
+    case CURVE_NONE:
+      memcpy (dest, src, samples * 4 * sizeof (gfloat));
+      break;
+
+    case CURVE_COLORS:
+      while (samples--)
+        {
+          dest[0] = gimp_curve_map_value_inline (curve_colors, src[0]);
+          dest[1] = gimp_curve_map_value_inline (curve_colors, src[1]);
+          dest[2] = gimp_curve_map_value_inline (curve_colors, src[2]);
+          /* don't apply the colors curve to the alpha channel */
+          dest[3] = src[3];
+
+          src  += 4;
+          dest += 4;
+        }
+      break;
+
+    case CURVE_RED:
+      while (samples--)
+        {
+          dest[0] = gimp_curve_map_value_inline (curve_red, src[0]);
+          dest[1] = src[1];
+          dest[2] = src[2];
+          dest[3] = src[3];
+
+          src  += 4;
+          dest += 4;
+        }
+      break;
+
+    case CURVE_GREEN:
+      while (samples--)
+        {
+          dest[0] = src[0];
+          dest[1] = gimp_curve_map_value_inline (curve_green, src[1]);
+          dest[2] = src[2];
+          dest[3] = src[3];
+
+          src  += 4;
+          dest += 4;
+        }
+      break;
+
+    case CURVE_BLUE:
+      while (samples--)
+        {
+          dest[0] = src[0];
+          dest[1] = src[1];
+          dest[2] = gimp_curve_map_value_inline (curve_blue, src[2]);
+          dest[3] = src[3];
+
+          src  += 4;
+          dest += 4;
+        }
+      break;
+
+     case CURVE_ALPHA:
+      while (samples--)
+        {
+          dest[0] = src[0];
+          dest[1] = src[1];
+          dest[2] = src[2];
+          dest[3] = gimp_curve_map_value_inline (curve_alpha, src[3]);
+
+          src  += 4;
+          dest += 4;
+        }
+      break;
+
+    case (CURVE_RED | CURVE_GREEN | CURVE_BLUE):
+      while (samples--)
+        {
+          dest[0] = gimp_curve_map_value_inline (curve_red,   src[0]);
+          dest[1] = gimp_curve_map_value_inline (curve_green, src[1]);
+          dest[2] = gimp_curve_map_value_inline (curve_blue,  src[2]);
+          dest[3] = src[3];
+
+          src  += 4;
+          dest += 4;
+        }
+      break;
+
+    default:
+      while (samples--)
+        {
+          dest[0] = gimp_curve_map_value_inline (curve_colors,
+                                                 gimp_curve_map_value_inline (curve_red,
+                                                                              src[0]));
+          dest[1] = gimp_curve_map_value_inline (curve_colors,
+                                                 gimp_curve_map_value_inline (curve_green,
+                                                                              src[1]));
+          dest[2] = gimp_curve_map_value_inline (curve_colors,
+                                                 gimp_curve_map_value_inline (curve_blue,
+                                                                              src[2]));
+          /* don't apply the colors curve to the alpha channel */
+          dest[3] = gimp_curve_map_value_inline (curve_alpha, src[3]);
+
+          src  += 4;
+          dest += 4;
+        }
+      break;
+    }
+}
+
+static guint
+gimp_curve_get_apply_mask (GimpCurve *curve_colors,
+                           GimpCurve *curve_red,
+                           GimpCurve *curve_green,
+                           GimpCurve *curve_blue,
+                           GimpCurve *curve_alpha)
+{
+  return ((gimp_curve_is_identity (curve_colors) ? 0 : CURVE_COLORS) |
+          (gimp_curve_is_identity (curve_red)    ? 0 : CURVE_RED)    |
+          (gimp_curve_is_identity (curve_green)  ? 0 : CURVE_GREEN)  |
+          (gimp_curve_is_identity (curve_blue)   ? 0 : CURVE_BLUE)   |
+          (gimp_curve_is_identity (curve_alpha)  ? 0 : CURVE_ALPHA));
+}
+
+static inline gdouble
+gimp_curve_map_value_inline (GimpCurve *curve,
+                             gdouble    value)
+{
+  if (curve->identity)
+    {
+      if (FINITE (value))
+        return CLAMP (value, 0.0, 1.0);
+
+      return 0.0;
+    }
+
+  /*  check for known values first, so broken values like NaN
+   *  delivered by broken drivers don't run into the interpolation
+   *  code
+   */
+  if (value > 0.0 && value < 1.0) /* interpolate the curve */
+    {
+      gdouble f;
+      gint    index;
+
+      /*  map value to the sample space  */
+      value = value * (curve->n_samples - 1);
+
+      /*  determine the indices of the closest sample points  */
+      index = (gint) value;
+
+      /*  calculate the position between the sample points  */
+      f = value - index;
+
+      return (1.0 - f) * curve->samples[index] + f * curve->samples[index + 1];
+    }
+  else if (value >= 1.0)
+    {
+      return curve->samples[curve->n_samples - 1];
+    }
+  else
+    {
+      return curve->samples[0];
+    }
+}
diff --git a/app/core/gimpcurve-map.h b/app/core/gimpcurve-map.h
new file mode 100644
index 0000000..185e2fc
--- /dev/null
+++ b/app/core/gimpcurve-map.h
@@ -0,0 +1,34 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_CURVE_MAP_H__
+#define __GIMP_CURVE_MAP_H__
+
+
+gdouble         gimp_curve_map_value         (GimpCurve     *curve,
+                                              gdouble        value);
+void            gimp_curve_map_pixels        (GimpCurve     *curve_colors,
+                                              GimpCurve     *curve_red,
+                                              GimpCurve     *curve_green,
+                                              GimpCurve     *curve_blue,
+                                              GimpCurve     *curve_alpha,
+                                              gfloat        *src,
+                                              gfloat        *dest,
+                                              glong          samples);
+
+
+#endif /* __GIMP_CURVE_MAP_H__ */
diff --git a/app/core/gimpcurve-save.c b/app/core/gimpcurve-save.c
new file mode 100644
index 0000000..2791b13
--- /dev/null
+++ b/app/core/gimpcurve-save.c
@@ -0,0 +1,44 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpconfig/gimpconfig.h"
+
+#include "core-types.h"
+
+#include "gimpcurve.h"
+#include "gimpcurve-save.h"
+
+
+gboolean
+gimp_curve_save (GimpData       *data,
+                 GOutputStream  *output,
+                 GError        **error)
+{
+  g_return_val_if_fail (GIMP_IS_CURVE (data), FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  return gimp_config_serialize_to_stream (GIMP_CONFIG (data),
+                                          output,
+                                          "GIMP curve file",
+                                          "end of GIMP curve file",
+                                          NULL, error);
+}
diff --git a/app/core/gimpcurve-save.h b/app/core/gimpcurve-save.h
new file mode 100644
index 0000000..98d504f
--- /dev/null
+++ b/app/core/gimpcurve-save.h
@@ -0,0 +1,28 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_CURVE_SAVE_H__
+#define __GIMP_CURVE_SAVE_H__
+
+
+/*  don't call this function directly, use gimp_data_save() instead  */
+gboolean   gimp_curve_save (GimpData       *data,
+                            GOutputStream  *output,
+                            GError        **error);
+
+
+#endif /* __GIMP_CURVE_SAVE_H__ */
diff --git a/app/core/gimpcurve.c b/app/core/gimpcurve.c
new file mode 100644
index 0000000..bde20b2
--- /dev/null
+++ b/app/core/gimpcurve.c
@@ -0,0 +1,1289 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <stdlib.h>
+#include <string.h> /* memcmp */
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpmath/gimpmath.h"
+#include "libgimpconfig/gimpconfig.h"
+
+#include "core-types.h"
+
+#include "gimpcurve.h"
+#include "gimpcurve-load.h"
+#include "gimpcurve-save.h"
+#include "gimpparamspecs.h"
+
+#include "gimp-intl.h"
+
+
+#define EPSILON 1e-6
+
+
+enum
+{
+  PROP_0,
+  PROP_CURVE_TYPE,
+  PROP_N_POINTS,
+  PROP_POINTS,
+  PROP_POINT_TYPES,
+  PROP_N_SAMPLES,
+  PROP_SAMPLES
+};
+
+
+/*  local function prototypes  */
+
+static void          gimp_curve_config_iface_init (GimpConfigInterface *iface);
+
+static void          gimp_curve_finalize          (GObject          *object);
+static void          gimp_curve_set_property      (GObject          *object,
+                                                   guint             property_id,
+                                                   const GValue     *value,
+                                                   GParamSpec       *pspec);
+static void          gimp_curve_get_property      (GObject          *object,
+                                                   guint             property_id,
+                                                   GValue           *value,
+                                                   GParamSpec       *pspec);
+
+static gint64        gimp_curve_get_memsize       (GimpObject       *object,
+                                                   gint64           *gui_size);
+
+static void          gimp_curve_get_preview_size  (GimpViewable     *viewable,
+                                                   gint              size,
+                                                   gboolean          popup,
+                                                   gboolean          dot_for_dot,
+                                                   gint             *width,
+                                                   gint             *height);
+static gboolean      gimp_curve_get_popup_size    (GimpViewable     *viewable,
+                                                   gint              width,
+                                                   gint              height,
+                                                   gboolean          dot_for_dot,
+                                                   gint             *popup_width,
+                                                   gint             *popup_height);
+static GimpTempBuf * gimp_curve_get_new_preview   (GimpViewable     *viewable,
+                                                   GimpContext      *context,
+                                                   gint              width,
+                                                   gint              height);
+static gchar       * gimp_curve_get_description   (GimpViewable     *viewable,
+                                                   gchar           **tooltip);
+
+static void          gimp_curve_dirty             (GimpData         *data);
+static const gchar * gimp_curve_get_extension     (GimpData         *data);
+static void          gimp_curve_data_copy         (GimpData         *data,
+                                                   GimpData         *src_data);
+
+static gboolean      gimp_curve_serialize         (GimpConfig       *config,
+                                                   GimpConfigWriter *writer,
+                                                   gpointer          data);
+static gboolean      gimp_curve_deserialize       (GimpConfig       *config,
+                                                   GScanner         *scanner,
+                                                   gint              nest_level,
+                                                   gpointer          data);
+static gboolean      gimp_curve_equal             (GimpConfig       *a,
+                                                   GimpConfig       *b);
+static void          _gimp_curve_reset            (GimpConfig       *config);
+static gboolean      gimp_curve_config_copy       (GimpConfig       *src,
+                                                   GimpConfig       *dest,
+                                                   GParamFlags       flags);
+
+static void          gimp_curve_calculate         (GimpCurve        *curve);
+static void          gimp_curve_plot              (GimpCurve        *curve,
+                                                   gint              p1,
+                                                   gint              p2,
+                                                   gint              p3,
+                                                   gint              p4);
+
+
+G_DEFINE_TYPE_WITH_CODE (GimpCurve, gimp_curve, GIMP_TYPE_DATA,
+                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_CONFIG,
+                                                gimp_curve_config_iface_init))
+
+#define parent_class gimp_curve_parent_class
+
+
+static void
+gimp_curve_class_init (GimpCurveClass *klass)
+{
+  GObjectClass      *object_class      = G_OBJECT_CLASS (klass);
+  GimpObjectClass   *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+  GimpViewableClass *viewable_class    = GIMP_VIEWABLE_CLASS (klass);
+  GimpDataClass     *data_class        = GIMP_DATA_CLASS (klass);
+  GParamSpec        *array_spec;
+
+  object_class->finalize            = gimp_curve_finalize;
+  object_class->set_property        = gimp_curve_set_property;
+  object_class->get_property        = gimp_curve_get_property;
+
+  gimp_object_class->get_memsize    = gimp_curve_get_memsize;
+
+  viewable_class->default_icon_name = "FIXME icon name";
+  viewable_class->get_preview_size  = gimp_curve_get_preview_size;
+  viewable_class->get_popup_size    = gimp_curve_get_popup_size;
+  viewable_class->get_new_preview   = gimp_curve_get_new_preview;
+  viewable_class->get_description   = gimp_curve_get_description;
+
+  data_class->dirty                 = gimp_curve_dirty;
+  data_class->save                  = gimp_curve_save;
+  data_class->get_extension         = gimp_curve_get_extension;
+  data_class->copy                  = gimp_curve_data_copy;
+
+  GIMP_CONFIG_PROP_ENUM (object_class, PROP_CURVE_TYPE,
+                         "curve-type",
+                         "Curve Type",
+                         "The curve type",
+                         GIMP_TYPE_CURVE_TYPE,
+                         GIMP_CURVE_SMOOTH, 0);
+
+  GIMP_CONFIG_PROP_INT (object_class, PROP_N_POINTS,
+                        "n-points",
+                        "Number of Points",
+                        "The number of points",
+                        0, G_MAXINT, 0,
+                        /* for backward compatibility */
+                        GIMP_CONFIG_PARAM_IGNORE);
+
+  array_spec = g_param_spec_double ("point", NULL, NULL,
+                                    -1.0, 1.0, 0.0, GIMP_PARAM_READWRITE);
+  g_object_class_install_property (object_class, PROP_POINTS,
+                                   gimp_param_spec_value_array ("points",
+                                                                NULL, NULL,
+                                                                array_spec,
+                                                                GIMP_PARAM_STATIC_STRINGS |
+                                                                GIMP_CONFIG_PARAM_FLAGS));
+
+  array_spec = g_param_spec_enum ("point-type", NULL, NULL,
+                                  GIMP_TYPE_CURVE_POINT_TYPE,
+                                  GIMP_CURVE_POINT_SMOOTH,
+                                  GIMP_PARAM_READWRITE);
+  g_object_class_install_property (object_class, PROP_POINT_TYPES,
+                                   gimp_param_spec_value_array ("point-types",
+                                                                NULL, NULL,
+                                                                array_spec,
+                                                                GIMP_PARAM_STATIC_STRINGS |
+                                                                GIMP_CONFIG_PARAM_FLAGS));
+
+  GIMP_CONFIG_PROP_INT  (object_class, PROP_N_SAMPLES,
+                         "n-samples",
+                         "Number of Samples",
+                         "The number of samples",
+                         256, 256, 256, 0);
+
+  array_spec = g_param_spec_double ("sample", NULL, NULL,
+                                    0.0, 1.0, 0.0, GIMP_PARAM_READWRITE);
+  g_object_class_install_property (object_class, PROP_SAMPLES,
+                                   gimp_param_spec_value_array ("samples",
+                                                                NULL, NULL,
+                                                                array_spec,
+                                                                GIMP_PARAM_STATIC_STRINGS |
+                                                                GIMP_CONFIG_PARAM_FLAGS));
+}
+
+static void
+gimp_curve_config_iface_init (GimpConfigInterface *iface)
+{
+  iface->serialize   = gimp_curve_serialize;
+  iface->deserialize = gimp_curve_deserialize;
+  iface->equal       = gimp_curve_equal;
+  iface->reset       = _gimp_curve_reset;
+  iface->copy        = gimp_curve_config_copy;
+}
+
+static void
+gimp_curve_init (GimpCurve *curve)
+{
+  curve->n_points  = 0;
+  curve->points    = NULL;
+  curve->n_samples = 0;
+  curve->samples   = NULL;
+  curve->identity  = FALSE;
+}
+
+static void
+gimp_curve_finalize (GObject *object)
+{
+  GimpCurve *curve = GIMP_CURVE (object);
+
+  g_clear_pointer (&curve->points,  g_free);
+  curve->n_points = 0;
+
+  g_clear_pointer (&curve->samples, g_free);
+  curve->n_samples = 0;
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gimp_curve_set_property (GObject      *object,
+                         guint         property_id,
+                         const GValue *value,
+                         GParamSpec   *pspec)
+{
+  GimpCurve *curve = GIMP_CURVE (object);
+
+  switch (property_id)
+    {
+    case PROP_CURVE_TYPE:
+      gimp_curve_set_curve_type (curve, g_value_get_enum (value));
+      break;
+
+    case PROP_N_POINTS:
+      /* ignored */
+      break;
+
+    case PROP_POINTS:
+      {
+        GimpValueArray *array = g_value_get_boxed (value);
+        GimpCurvePoint *points;
+        gint            length;
+        gint            n_points;
+        gint            i;
+
+        if (! array)
+          {
+            gimp_curve_clear_points (curve);
+
+            break;
+          }
+
+        length = gimp_value_array_length (array) / 2;
+
+        n_points = 0;
+        points   = g_new0 (GimpCurvePoint, length);
+
+        for (i = 0; i < length; i++)
+          {
+            GValue *x = gimp_value_array_index (array, i * 2);
+            GValue *y = gimp_value_array_index (array, i * 2 + 1);
+
+            /* for backward compatibility */
+            if (g_value_get_double (x) < 0.0)
+              continue;
+
+            points[n_points].x = CLAMP (g_value_get_double (x), 0.0, 1.0);
+            points[n_points].y = CLAMP (g_value_get_double (y), 0.0, 1.0);
+
+            if (n_points > 0)
+              {
+                points[n_points].x = MAX (points[n_points].x,
+                                          points[n_points - 1].x);
+              }
+
+            if (n_points < curve->n_points)
+              points[n_points].type = curve->points[n_points].type;
+            else
+              points[n_points].type = GIMP_CURVE_POINT_SMOOTH;
+
+            n_points++;
+          }
+
+        g_free (curve->points);
+
+        curve->n_points = n_points;
+        curve->points   = points;
+
+        g_object_notify (object, "n-points");
+        g_object_notify (object, "point-types");
+      }
+      break;
+
+    case PROP_POINT_TYPES:
+      {
+        GimpValueArray *array = g_value_get_boxed (value);
+        GimpCurvePoint *points;
+        gint            length;
+        gdouble         x     = 0.0;
+        gdouble         y     = 0.0;
+        gint            i;
+
+        if (! array)
+          {
+            gimp_curve_clear_points (curve);
+
+            break;
+          }
+
+        length = gimp_value_array_length (array);
+
+        points = g_new0 (GimpCurvePoint, length);
+
+        for (i = 0; i < length; i++)
+          {
+            GValue *type = gimp_value_array_index (array, i);
+
+            points[i].type = g_value_get_enum (type);
+
+            if (i < curve->n_points)
+              {
+                x = curve->points[i].x;
+                y = curve->points[i].y;
+              }
+
+            points[i].x = x;
+            points[i].y = y;
+          }
+
+        g_free (curve->points);
+
+        curve->n_points = length;
+        curve->points   = points;
+
+        g_object_notify (object, "n-points");
+        g_object_notify (object, "points");
+      }
+      break;
+
+    case PROP_N_SAMPLES:
+      gimp_curve_set_n_samples (curve, g_value_get_int (value));
+      break;
+
+    case PROP_SAMPLES:
+      {
+        GimpValueArray *array = g_value_get_boxed (value);
+        gint            length;
+        gint            i;
+
+        if (! array)
+          break;
+
+        length = gimp_value_array_length (array);
+
+        for (i = 0; i < curve->n_samples && i < length; i++)
+          {
+            GValue *v = gimp_value_array_index (array, i);
+
+            curve->samples[i] = CLAMP (g_value_get_double (v), 0.0, 1.0);
+          }
+      }
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_curve_get_property (GObject    *object,
+                         guint       property_id,
+                         GValue     *value,
+                         GParamSpec *pspec)
+{
+  GimpCurve *curve = GIMP_CURVE (object);
+
+  switch (property_id)
+    {
+    case PROP_CURVE_TYPE:
+      g_value_set_enum (value, curve->curve_type);
+      break;
+
+    case PROP_N_POINTS:
+      g_value_set_int (value, curve->n_points);
+      break;
+
+    case PROP_POINTS:
+      {
+        GimpValueArray *array = gimp_value_array_new (curve->n_points * 2);
+        GValue          v     = G_VALUE_INIT;
+        gint            i;
+
+        g_value_init (&v, G_TYPE_DOUBLE);
+
+        for (i = 0; i < curve->n_points; i++)
+          {
+            g_value_set_double (&v, curve->points[i].x);
+            gimp_value_array_append (array, &v);
+
+            g_value_set_double (&v, curve->points[i].y);
+            gimp_value_array_append (array, &v);
+          }
+
+        g_value_unset (&v);
+
+        g_value_take_boxed (value, array);
+      }
+      break;
+
+    case PROP_POINT_TYPES:
+      {
+        GimpValueArray *array = gimp_value_array_new (curve->n_points);
+        GValue          v     = G_VALUE_INIT;
+        gint            i;
+
+        g_value_init (&v, GIMP_TYPE_CURVE_POINT_TYPE);
+
+        for (i = 0; i < curve->n_points; i++)
+          {
+            g_value_set_enum (&v, curve->points[i].type);
+            gimp_value_array_append (array, &v);
+          }
+
+        g_value_unset (&v);
+
+        g_value_take_boxed (value, array);
+      }
+      break;
+
+    case PROP_N_SAMPLES:
+      g_value_set_int (value, curve->n_samples);
+      break;
+
+    case PROP_SAMPLES:
+      {
+        GimpValueArray *array = gimp_value_array_new (curve->n_samples);
+        GValue          v     = G_VALUE_INIT;
+        gint            i;
+
+        g_value_init (&v, G_TYPE_DOUBLE);
+
+        for (i = 0; i < curve->n_samples; i++)
+          {
+            g_value_set_double (&v, curve->samples[i]);
+            gimp_value_array_append (array, &v);
+          }
+
+        g_value_unset (&v);
+
+        g_value_take_boxed (value, array);
+      }
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static gint64
+gimp_curve_get_memsize (GimpObject *object,
+                        gint64     *gui_size)
+{
+  GimpCurve *curve   = GIMP_CURVE (object);
+  gint64     memsize = 0;
+
+  memsize += curve->n_points  * sizeof (GimpCurvePoint);
+  memsize += curve->n_samples * sizeof (gdouble);
+
+  return memsize + GIMP_OBJECT_CLASS (parent_class)->get_memsize (object,
+                                                                  gui_size);
+}
+
+static void
+gimp_curve_get_preview_size (GimpViewable *viewable,
+                             gint          size,
+                             gboolean      popup,
+                             gboolean      dot_for_dot,
+                             gint         *width,
+                             gint         *height)
+{
+  *width  = size;
+  *height = size;
+}
+
+static gboolean
+gimp_curve_get_popup_size (GimpViewable *viewable,
+                           gint          width,
+                           gint          height,
+                           gboolean      dot_for_dot,
+                           gint         *popup_width,
+                           gint         *popup_height)
+{
+  *popup_width  = width  * 2;
+  *popup_height = height * 2;
+
+  return TRUE;
+}
+
+static GimpTempBuf *
+gimp_curve_get_new_preview (GimpViewable *viewable,
+                            GimpContext  *context,
+                            gint          width,
+                            gint          height)
+{
+  return NULL;
+}
+
+static gchar *
+gimp_curve_get_description (GimpViewable  *viewable,
+                            gchar        **tooltip)
+{
+  GimpCurve *curve = GIMP_CURVE (viewable);
+
+  return g_strdup_printf ("%s", gimp_object_get_name (curve));
+}
+
+static void
+gimp_curve_dirty (GimpData *data)
+{
+  GimpCurve *curve = GIMP_CURVE (data);
+
+  curve->identity = FALSE;
+
+  gimp_curve_calculate (curve);
+
+  GIMP_DATA_CLASS (parent_class)->dirty (data);
+}
+
+static const gchar *
+gimp_curve_get_extension (GimpData *data)
+{
+  return GIMP_CURVE_FILE_EXTENSION;
+}
+
+static void
+gimp_curve_data_copy (GimpData *data,
+                      GimpData *src_data)
+{
+  gimp_data_freeze (data);
+
+  gimp_config_copy (GIMP_CONFIG (src_data),
+                    GIMP_CONFIG (data), 0);
+
+  gimp_data_thaw (data);
+}
+
+static gboolean
+gimp_curve_serialize (GimpConfig       *config,
+                      GimpConfigWriter *writer,
+                      gpointer          data)
+{
+  return gimp_config_serialize_properties (config, writer);
+}
+
+static gboolean
+gimp_curve_deserialize (GimpConfig *config,
+                        GScanner   *scanner,
+                        gint        nest_level,
+                        gpointer    data)
+{
+  gboolean success;
+
+  success = gimp_config_deserialize_properties (config, scanner, nest_level);
+
+  GIMP_CURVE (config)->identity = FALSE;
+
+  return success;
+}
+
+static gboolean
+gimp_curve_equal (GimpConfig *a,
+                  GimpConfig *b)
+{
+  GimpCurve *a_curve = GIMP_CURVE (a);
+  GimpCurve *b_curve = GIMP_CURVE (b);
+
+  if (a_curve->curve_type != b_curve->curve_type)
+    return FALSE;
+
+  if (a_curve->n_points != b_curve->n_points ||
+      memcmp (a_curve->points, b_curve->points,
+              sizeof (GimpCurvePoint) * a_curve->n_points))
+    {
+      return FALSE;
+    }
+
+  if (a_curve->n_samples != b_curve->n_samples ||
+      memcmp (a_curve->samples, b_curve->samples,
+              sizeof (gdouble) * a_curve->n_samples))
+    {
+      return FALSE;
+    }
+
+  return TRUE;
+}
+
+static void
+_gimp_curve_reset (GimpConfig *config)
+{
+  gimp_curve_reset (GIMP_CURVE (config), TRUE);
+}
+
+static gboolean
+gimp_curve_config_copy (GimpConfig  *src,
+                        GimpConfig  *dest,
+                        GParamFlags  flags)
+{
+  GimpCurve *src_curve  = GIMP_CURVE (src);
+  GimpCurve *dest_curve = GIMP_CURVE (dest);
+
+  /* make sure the curve type is copied *before* the points, so that we don't
+   * overwrite the copied points when changing the type
+   */
+  dest_curve->curve_type = src_curve->curve_type;
+
+  gimp_config_sync (G_OBJECT (src), G_OBJECT (dest), flags);
+
+  dest_curve->identity = src_curve->identity;
+
+  gimp_data_dirty (GIMP_DATA (dest));
+
+  return TRUE;
+}
+
+
+/*  public functions  */
+
+GimpData *
+gimp_curve_new (const gchar *name)
+{
+  g_return_val_if_fail (name != NULL, NULL);
+  g_return_val_if_fail (*name != '\0', NULL);
+
+  return g_object_new (GIMP_TYPE_CURVE,
+                       "name", name,
+                       NULL);
+}
+
+GimpData *
+gimp_curve_get_standard (void)
+{
+  static GimpData *standard_curve = NULL;
+
+  if (! standard_curve)
+    {
+      standard_curve = gimp_curve_new ("Standard");
+
+      gimp_data_clean (standard_curve);
+      gimp_data_make_internal (standard_curve,
+                               "gimp-curve-standard");
+
+      g_object_ref (standard_curve);
+    }
+
+  return standard_curve;
+}
+
+void
+gimp_curve_reset (GimpCurve *curve,
+                  gboolean   reset_type)
+{
+  gint i;
+
+  g_return_if_fail (GIMP_IS_CURVE (curve));
+
+  g_object_freeze_notify (G_OBJECT (curve));
+
+  for (i = 0; i < curve->n_samples; i++)
+    curve->samples[i] = (gdouble) i / (gdouble) (curve->n_samples - 1);
+
+  g_object_notify (G_OBJECT (curve), "samples");
+
+  g_free (curve->points);
+
+  curve->n_points = 2;
+  curve->points   = g_new0 (GimpCurvePoint, 2);
+
+  curve->points[0].x    = 0.0;
+  curve->points[0].y    = 0.0;
+  curve->points[0].type = GIMP_CURVE_POINT_SMOOTH;
+
+  curve->points[1].x    = 1.0;
+  curve->points[1].y    = 1.0;
+  curve->points[1].type = GIMP_CURVE_POINT_SMOOTH;
+
+  g_object_notify (G_OBJECT (curve), "n-points");
+  g_object_notify (G_OBJECT (curve), "points");
+  g_object_notify (G_OBJECT (curve), "point-types");
+
+  if (reset_type)
+    {
+      curve->curve_type = GIMP_CURVE_SMOOTH;
+      g_object_notify (G_OBJECT (curve), "curve-type");
+    }
+
+  curve->identity = TRUE;
+
+  g_object_thaw_notify (G_OBJECT (curve));
+
+  gimp_data_dirty (GIMP_DATA (curve));
+}
+
+void
+gimp_curve_set_curve_type (GimpCurve     *curve,
+                           GimpCurveType  curve_type)
+{
+  g_return_if_fail (GIMP_IS_CURVE (curve));
+
+  if (curve->curve_type != curve_type)
+    {
+      gimp_data_freeze (GIMP_DATA (curve));
+
+      g_object_freeze_notify (G_OBJECT (curve));
+
+      curve->curve_type = curve_type;
+
+      if (curve_type == GIMP_CURVE_SMOOTH)
+        {
+          gint i;
+
+          g_free (curve->points);
+
+          /*  pick some points from the curve and make them control
+           *  points
+           */
+          curve->n_points = 9;
+          curve->points   = g_new0 (GimpCurvePoint, 9);
+
+          for (i = 0; i < curve->n_points; i++)
+            {
+              gint sample = i * (curve->n_samples - 1) / (curve->n_points - 1);
+
+              curve->points[i].x    = (gdouble) sample /
+                                      (gdouble) (curve->n_samples - 1);
+              curve->points[i].y    = curve->samples[sample];
+              curve->points[i].type = GIMP_CURVE_POINT_SMOOTH;
+            }
+
+          g_object_notify (G_OBJECT (curve), "n-points");
+          g_object_notify (G_OBJECT (curve), "points");
+          g_object_notify (G_OBJECT (curve), "point-types");
+        }
+      else
+        {
+          gimp_curve_clear_points (curve);
+        }
+
+      g_object_notify (G_OBJECT (curve), "curve-type");
+
+      g_object_thaw_notify (G_OBJECT (curve));
+
+      gimp_data_thaw (GIMP_DATA (curve));
+    }
+}
+
+GimpCurveType
+gimp_curve_get_curve_type (GimpCurve *curve)
+{
+  g_return_val_if_fail (GIMP_IS_CURVE (curve), GIMP_CURVE_SMOOTH);
+
+  return curve->curve_type;
+}
+
+gint
+gimp_curve_get_n_points (GimpCurve *curve)
+{
+  g_return_val_if_fail (GIMP_IS_CURVE (curve), 0);
+
+  return curve->n_points;
+}
+
+void
+gimp_curve_set_n_samples (GimpCurve *curve,
+                          gint       n_samples)
+{
+  g_return_if_fail (GIMP_IS_CURVE (curve));
+  g_return_if_fail (n_samples >= 256);
+  g_return_if_fail (n_samples <= 4096);
+
+  if (n_samples != curve->n_samples)
+    {
+      gint i;
+
+      g_object_freeze_notify (G_OBJECT (curve));
+
+      curve->n_samples = n_samples;
+      g_object_notify (G_OBJECT (curve), "n-samples");
+
+      curve->samples = g_renew (gdouble, curve->samples, curve->n_samples);
+
+      for (i = 0; i < curve->n_samples; i++)
+        curve->samples[i] = (gdouble) i / (gdouble) (curve->n_samples - 1);
+
+      g_object_notify (G_OBJECT (curve), "samples");
+
+      if (curve->curve_type == GIMP_CURVE_FREE)
+        curve->identity = TRUE;
+
+      g_object_thaw_notify (G_OBJECT (curve));
+    }
+}
+
+gint
+gimp_curve_get_n_samples (GimpCurve *curve)
+{
+  g_return_val_if_fail (GIMP_IS_CURVE (curve), 0);
+
+  return curve->n_samples;
+}
+
+gint
+gimp_curve_get_point_at (GimpCurve *curve,
+                         gdouble    x)
+{
+  gint    closest_point = -1;
+  gdouble distance      = EPSILON;
+  gint    i;
+
+  g_return_val_if_fail (GIMP_IS_CURVE (curve), -1);
+
+  for (i = 0; i < curve->n_points; i++)
+    {
+      gdouble point_distance;
+
+      point_distance = fabs (x - curve->points[i].x);
+
+      if (point_distance <= distance)
+        {
+          closest_point = i;
+          distance      = point_distance;
+        }
+    }
+
+  return closest_point;
+}
+
+gint
+gimp_curve_get_closest_point (GimpCurve *curve,
+                              gdouble    x,
+                              gdouble    y,
+                              gdouble    max_distance)
+{
+  gint    closest_point = -1;
+  gdouble distance2     = G_MAXDOUBLE;
+  gint    i;
+
+  g_return_val_if_fail (GIMP_IS_CURVE (curve), -1);
+
+  if (max_distance >= 0.0)
+    distance2 = SQR (max_distance);
+
+  for (i = curve->n_points - 1; i >= 0; i--)
+    {
+      gdouble point_distance2;
+
+      point_distance2 = SQR (x - curve->points[i].x) +
+                        SQR (y - curve->points[i].y);
+
+      if (point_distance2 <= distance2)
+        {
+          closest_point = i;
+          distance2     = point_distance2;
+        }
+    }
+
+  return closest_point;
+}
+
+gint
+gimp_curve_add_point (GimpCurve *curve,
+                      gdouble    x,
+                      gdouble    y)
+{
+  GimpCurvePoint *points;
+  gint            point;
+
+  g_return_val_if_fail (GIMP_IS_CURVE (curve), -1);
+
+  if (curve->curve_type == GIMP_CURVE_FREE)
+    return -1;
+
+  x = CLAMP (x, 0.0, 1.0);
+  y = CLAMP (y, 0.0, 1.0);
+
+  for (point = 0; point < curve->n_points; point++)
+    {
+      if (curve->points[point].x > x)
+        break;
+    }
+
+  points = g_new0 (GimpCurvePoint, curve->n_points + 1);
+
+  memcpy (points,         curve->points,
+          point * sizeof (GimpCurvePoint));
+  memcpy (points + point + 1, curve->points + point,
+          (curve->n_points - point) * sizeof (GimpCurvePoint));
+
+  points[point].x    = x;
+  points[point].y    = y;
+  points[point].type = GIMP_CURVE_POINT_SMOOTH;
+
+  g_free (curve->points);
+
+  curve->n_points++;
+  curve->points = points;
+
+  g_object_notify (G_OBJECT (curve), "n-points");
+  g_object_notify (G_OBJECT (curve), "points");
+  g_object_notify (G_OBJECT (curve), "point-types");
+
+  gimp_data_dirty (GIMP_DATA (curve));
+
+  return point;
+}
+
+void
+gimp_curve_delete_point (GimpCurve *curve,
+                         gint       point)
+{
+  GimpCurvePoint *points;
+
+  g_return_if_fail (GIMP_IS_CURVE (curve));
+  g_return_if_fail (point >= 0 && point < curve->n_points);
+
+  points = g_new0 (GimpCurvePoint, curve->n_points - 1);
+
+  memcpy (points,         curve->points,
+          point * sizeof (GimpCurvePoint));
+  memcpy (points + point, curve->points + point + 1,
+          (curve->n_points - point - 1) * sizeof (GimpCurvePoint));
+
+  g_free (curve->points);
+
+  curve->n_points--;
+  curve->points = points;
+
+  g_object_notify (G_OBJECT (curve), "n-points");
+  g_object_notify (G_OBJECT (curve), "points");
+  g_object_notify (G_OBJECT (curve), "point-types");
+
+  gimp_data_dirty (GIMP_DATA (curve));
+}
+
+void
+gimp_curve_set_point (GimpCurve *curve,
+                      gint       point,
+                      gdouble    x,
+                      gdouble    y)
+{
+  g_return_if_fail (GIMP_IS_CURVE (curve));
+  g_return_if_fail (point >= 0 && point < curve->n_points);
+
+  curve->points[point].x = CLAMP (x, 0.0, 1.0);
+  curve->points[point].y = CLAMP (y, 0.0, 1.0);
+
+  if (point > 0)
+    curve->points[point].x = MAX (x, curve->points[point - 1].x);
+
+  if (point < curve->n_points - 1)
+    curve->points[point].x = MIN (x, curve->points[point + 1].x);
+
+  g_object_notify (G_OBJECT (curve), "points");
+
+  gimp_data_dirty (GIMP_DATA (curve));
+}
+
+void
+gimp_curve_move_point (GimpCurve *curve,
+                       gint       point,
+                       gdouble    y)
+{
+  g_return_if_fail (GIMP_IS_CURVE (curve));
+  g_return_if_fail (point >= 0 && point < curve->n_points);
+
+  curve->points[point].y = CLAMP (y, 0.0, 1.0);
+
+  g_object_notify (G_OBJECT (curve), "points");
+
+  gimp_data_dirty (GIMP_DATA (curve));
+}
+
+void
+gimp_curve_get_point (GimpCurve *curve,
+                      gint       point,
+                      gdouble   *x,
+                      gdouble   *y)
+{
+  g_return_if_fail (GIMP_IS_CURVE (curve));
+  g_return_if_fail (point >= 0 && point < curve->n_points);
+
+  if (x) *x = curve->points[point].x;
+  if (y) *y = curve->points[point].y;
+}
+
+void
+gimp_curve_set_point_type (GimpCurve          *curve,
+                           gint                point,
+                           GimpCurvePointType  type)
+{
+  g_return_if_fail (GIMP_IS_CURVE (curve));
+  g_return_if_fail (point >= 0 && point < curve->n_points);
+
+  curve->points[point].type = type;
+
+  g_object_notify (G_OBJECT (curve), "point-types");
+
+  gimp_data_dirty (GIMP_DATA (curve));
+}
+
+GimpCurvePointType
+gimp_curve_get_point_type (GimpCurve *curve,
+                           gint       point)
+{
+  g_return_val_if_fail (GIMP_IS_CURVE (curve), GIMP_CURVE_POINT_SMOOTH);
+  g_return_val_if_fail (point >= 0 && point < curve->n_points, GIMP_CURVE_POINT_SMOOTH);
+
+  return curve->points[point].type;
+}
+
+void
+gimp_curve_clear_points (GimpCurve *curve)
+{
+  g_return_if_fail (GIMP_IS_CURVE (curve));
+
+  if (curve->points)
+    {
+      g_clear_pointer (&curve->points, g_free);
+      curve->n_points = 0;
+
+      g_object_notify (G_OBJECT (curve), "n-points");
+      g_object_notify (G_OBJECT (curve), "points");
+      g_object_notify (G_OBJECT (curve), "point-types");
+
+      gimp_data_dirty (GIMP_DATA (curve));
+    }
+}
+
+void
+gimp_curve_set_curve (GimpCurve *curve,
+                      gdouble    x,
+                      gdouble    y)
+{
+  g_return_if_fail (GIMP_IS_CURVE (curve));
+  g_return_if_fail (x >= 0 && x <= 1.0);
+  g_return_if_fail (y >= 0 && y <= 1.0);
+
+  if (curve->curve_type == GIMP_CURVE_SMOOTH)
+    return;
+
+  curve->samples[ROUND (x * (gdouble) (curve->n_samples - 1))] = y;
+
+  g_object_notify (G_OBJECT (curve), "samples");
+
+  gimp_data_dirty (GIMP_DATA (curve));
+}
+
+/**
+ * gimp_curve_is_identity:
+ * @curve: a #GimpCurve object
+ *
+ * If this function returns %TRUE, then the curve maps each value to
+ * itself. If it returns %FALSE, then this assumption can not be made.
+ *
+ * Return value: %TRUE if the curve is an identity mapping, %FALSE otherwise.
+ **/
+gboolean
+gimp_curve_is_identity (GimpCurve *curve)
+{
+  g_return_val_if_fail (GIMP_IS_CURVE (curve), FALSE);
+
+  return curve->identity;
+}
+
+void
+gimp_curve_get_uchar (GimpCurve *curve,
+                      gint       n_samples,
+                      guchar    *samples)
+{
+  gint i;
+
+  g_return_if_fail (GIMP_IS_CURVE (curve));
+  /* FIXME: support n_samples != curve->n_samples */
+  g_return_if_fail (n_samples == curve->n_samples);
+  g_return_if_fail (samples != NULL);
+
+  for (i = 0; i < curve->n_samples; i++)
+    samples[i] = curve->samples[i] * 255.999;
+}
+
+
+/*  private functions  */
+
+static void
+gimp_curve_calculate (GimpCurve *curve)
+{
+  gint i;
+  gint p1, p2, p3, p4;
+
+  if (gimp_data_is_frozen (GIMP_DATA (curve)))
+    return;
+
+  switch (curve->curve_type)
+    {
+    case GIMP_CURVE_SMOOTH:
+      /*  Initialize boundary curve points */
+      if (curve->n_points > 0)
+        {
+          GimpCurvePoint point;
+          gint           boundary;
+
+          point    = curve->points[0];
+          boundary = ROUND (point.x * (gdouble) (curve->n_samples - 1));
+
+          for (i = 0; i < boundary; i++)
+            curve->samples[i] = point.y;
+
+          point    = curve->points[curve->n_points - 1];
+          boundary = ROUND (point.x * (gdouble) (curve->n_samples - 1));
+
+          for (i = boundary; i < curve->n_samples; i++)
+            curve->samples[i] = point.y;
+        }
+
+      for (i = 0; i < curve->n_points - 1; i++)
+        {
+          p1 = MAX (i - 1, 0);
+          p2 = i;
+          p3 = i + 1;
+          p4 = MIN (i + 2, curve->n_points - 1);
+
+          if (curve->points[p2].type == GIMP_CURVE_POINT_CORNER)
+            p1 = p2;
+
+          if (curve->points[p3].type == GIMP_CURVE_POINT_CORNER)
+            p4 = p3;
+
+          gimp_curve_plot (curve, p1, p2, p3, p4);
+        }
+
+      /* ensure that the control points are used exactly */
+      for (i = 0; i < curve->n_points; i++)
+        {
+          gdouble x = curve->points[i].x;
+          gdouble y = curve->points[i].y;
+
+          curve->samples[ROUND (x * (gdouble) (curve->n_samples - 1))] = y;
+        }
+
+      g_object_notify (G_OBJECT (curve), "samples");
+      break;
+
+    case GIMP_CURVE_FREE:
+      break;
+    }
+}
+
+/*
+ * This function calculates the curve values between the control points
+ * p2 and p3, taking the potentially existing neighbors p1 and p4 into
+ * account.
+ *
+ * This function uses a cubic bezier curve for the individual segments and
+ * calculates the necessary intermediate control points depending on the
+ * neighbor curve control points.
+ */
+static void
+gimp_curve_plot (GimpCurve *curve,
+                 gint       p1,
+                 gint       p2,
+                 gint       p3,
+                 gint       p4)
+{
+  gint    i;
+  gdouble x0, x3;
+  gdouble y0, y1, y2, y3;
+  gdouble dx, dy;
+  gdouble slope;
+
+  /* the outer control points for the bezier curve. */
+  x0 = curve->points[p2].x;
+  y0 = curve->points[p2].y;
+  x3 = curve->points[p3].x;
+  y3 = curve->points[p3].y;
+
+  /*
+   * the x values of the inner control points are fixed at
+   * x1 = 2/3*x0 + 1/3*x3   and  x2 = 1/3*x0 + 2/3*x3
+   * this ensures that the x values increase linearly with the
+   * parameter t and enables us to skip the calculation of the x
+   * values altogether - just calculate y(t) evenly spaced.
+   */
+
+  dx = x3 - x0;
+  dy = y3 - y0;
+
+  if (dx <= EPSILON)
+    {
+      gint index;
+
+      index = ROUND (x0 * (gdouble) (curve->n_samples - 1));
+
+      curve->samples[index] = y3;
+
+      return;
+    }
+
+  if (p1 == p2 && p3 == p4)
+    {
+      /* No information about the neighbors,
+       * calculate y1 and y2 to get a straight line
+       */
+      y1 = y0 + dy / 3.0;
+      y2 = y0 + dy * 2.0 / 3.0;
+    }
+  else if (p1 == p2 && p3 != p4)
+    {
+      /* only the right neighbor is available. Make the tangent at the
+       * right endpoint parallel to the line between the left endpoint
+       * and the right neighbor. Then point the tangent at the left towards
+       * the control handle of the right tangent, to ensure that the curve
+       * does not have an inflection point.
+       */
+      slope = (curve->points[p4].y - y0) / (curve->points[p4].x - x0);
+
+      y2 = y3 - slope * dx / 3.0;
+      y1 = y0 + (y2 - y0) / 2.0;
+    }
+  else if (p1 != p2 && p3 == p4)
+    {
+      /* see previous case */
+      slope = (y3 - curve->points[p1].y) / (x3 - curve->points[p1].x);
+
+      y1 = y0 + slope * dx / 3.0;
+      y2 = y3 + (y1 - y3) / 2.0;
+    }
+  else /* (p1 != p2 && p3 != p4) */
+    {
+      /* Both neighbors are available. Make the tangents at the endpoints
+       * parallel to the line between the opposite endpoint and the adjacent
+       * neighbor.
+       */
+      slope = (y3 - curve->points[p1].y) / (x3 - curve->points[p1].x);
+
+      y1 = y0 + slope * dx / 3.0;
+
+      slope = (curve->points[p4].y - y0) / (curve->points[p4].x - x0);
+
+      y2 = y3 - slope * dx / 3.0;
+    }
+
+  /*
+   * finally calculate the y(t) values for the given bezier values. We can
+   * use homogeneously distributed values for t, since x(t) increases linearly.
+   */
+  for (i = 0; i <= ROUND (dx * (gdouble) (curve->n_samples - 1)); i++)
+    {
+      gdouble y, t;
+      gint    index;
+
+      t = i / dx / (gdouble) (curve->n_samples - 1);
+      y =     y0 * (1-t) * (1-t) * (1-t) +
+          3 * y1 * (1-t) * (1-t) * t     +
+          3 * y2 * (1-t) * t     * t     +
+              y3 * t     * t     * t;
+
+      index = i + ROUND (x0 * (gdouble) (curve->n_samples - 1));
+
+      if (index < curve->n_samples)
+        curve->samples[index] = CLAMP (y, 0.0, 1.0);
+    }
+}
diff --git a/app/core/gimpcurve.h b/app/core/gimpcurve.h
new file mode 100644
index 0000000..71654aa
--- /dev/null
+++ b/app/core/gimpcurve.h
@@ -0,0 +1,124 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_CURVE_H__
+#define __GIMP_CURVE_H__
+
+
+#include "gimpdata.h"
+
+
+#define GIMP_TYPE_CURVE            (gimp_curve_get_type ())
+#define GIMP_CURVE(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_CURVE, GimpCurve))
+#define GIMP_CURVE_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_CURVE, GimpCurveClass))
+#define GIMP_IS_CURVE(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_CURVE))
+#define GIMP_IS_CURVE_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_CURVE))
+#define GIMP_CURVE_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_CURVE, GimpCurveClass))
+
+
+typedef struct _GimpCurvePoint GimpCurvePoint;
+typedef struct _GimpCurveClass GimpCurveClass;
+
+struct _GimpCurvePoint
+{
+  gdouble            x;
+  gdouble            y;
+
+  GimpCurvePointType type;
+};
+
+struct _GimpCurve
+{
+  GimpData        parent_instance;
+
+  GimpCurveType   curve_type;
+
+  gint            n_points;
+  GimpCurvePoint *points;
+
+  gint            n_samples;
+  gdouble        *samples;
+
+  gboolean        identity;  /* whether the curve is an identity mapping */
+};
+
+struct _GimpCurveClass
+{
+  GimpDataClass  parent_class;
+};
+
+
+GType                gimp_curve_get_type          (void) G_GNUC_CONST;
+
+GimpData           * gimp_curve_new               (const gchar        *name);
+GimpData           * gimp_curve_get_standard      (void);
+
+void                 gimp_curve_reset             (GimpCurve          *curve,
+                                                   gboolean            reset_type);
+
+void                 gimp_curve_set_curve_type    (GimpCurve          *curve,
+                                                   GimpCurveType       curve_type);
+GimpCurveType        gimp_curve_get_curve_type    (GimpCurve          *curve);
+
+gint                 gimp_curve_get_n_points      (GimpCurve          *curve);
+
+void                 gimp_curve_set_n_samples     (GimpCurve          *curve,
+                                                   gint                n_samples);
+gint                 gimp_curve_get_n_samples     (GimpCurve          *curve);
+
+gint                 gimp_curve_get_point_at      (GimpCurve          *curve,
+                                                   gdouble             x);
+gint                 gimp_curve_get_closest_point (GimpCurve          *curve,
+                                                   gdouble             x,
+                                                   gdouble             y,
+                                                   gdouble             max_distance);
+
+gint                 gimp_curve_add_point         (GimpCurve          *curve,
+                                                   gdouble             x,
+                                                   gdouble             y);
+void                 gimp_curve_delete_point      (GimpCurve          *curve,
+                                                   gint                point);
+void                 gimp_curve_set_point         (GimpCurve          *curve,
+                                                   gint                point,
+                                                   gdouble             x,
+                                                   gdouble             y);
+void                 gimp_curve_move_point        (GimpCurve          *curve,
+                                                   gint                point,
+                                                   gdouble             y);
+void                 gimp_curve_get_point         (GimpCurve          *curve,
+                                                   gint                point,
+                                                   gdouble            *x,
+                                                   gdouble            *y);
+void                 gimp_curve_set_point_type    (GimpCurve          *curve,
+                                                   gint                point,
+                                                   GimpCurvePointType  type);
+GimpCurvePointType   gimp_curve_get_point_type    (GimpCurve          *curve,
+                                                   gint                point);
+void                 gimp_curve_clear_points      (GimpCurve          *curve);
+
+void                 gimp_curve_set_curve         (GimpCurve          *curve,
+                                                   gdouble             x,
+                                                   gdouble             y);
+
+gboolean             gimp_curve_is_identity       (GimpCurve          *curve);
+
+void                 gimp_curve_get_uchar         (GimpCurve          *curve,
+                                                   gint                n_samples,
+                                                   guchar             *samples);
+
+
+#endif /* __GIMP_CURVE_H__ */
diff --git a/app/core/gimpdashpattern.c b/app/core/gimpdashpattern.c
new file mode 100644
index 0000000..e9fb9fc
--- /dev/null
+++ b/app/core/gimpdashpattern.c
@@ -0,0 +1,355 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1999 Spencer Kimball and Peter Mattis
+ *
+ * gimpdashpattern.c
+ * Copyright (C) 2003 Simon Budig
+ * Copyright (C) 2005 Sven Neumann
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gio/gio.h>
+
+#include "libgimpbase/gimpbase.h"
+
+#include "core-types.h"
+
+#include "gimpdashpattern.h"
+
+
+GType
+gimp_dash_pattern_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    type = g_boxed_type_register_static ("GimpDashPattern",
+                                         (GBoxedCopyFunc) gimp_dash_pattern_copy,
+                                         (GBoxedFreeFunc) gimp_dash_pattern_free);
+
+  return type;
+}
+
+GArray *
+gimp_dash_pattern_new_from_preset (GimpDashPreset preset)
+{
+  GArray *pattern;
+  gdouble dash;
+  gint    i;
+
+  pattern = g_array_new (FALSE, FALSE, sizeof (gdouble));
+
+  switch (preset)
+    {
+    case GIMP_DASH_CUSTOM:
+      g_warning ("GIMP_DASH_CUSTOM passed to gimp_dash_pattern_from_preset()");
+      break;
+
+    case GIMP_DASH_LINE:
+      break;
+
+    case GIMP_DASH_LONG_DASH:
+      dash = 9.0; g_array_append_val (pattern, dash);
+      dash = 3.0; g_array_append_val (pattern, dash);
+      break;
+
+    case GIMP_DASH_MEDIUM_DASH:
+      dash = 6.0; g_array_append_val (pattern, dash);
+      dash = 6.0; g_array_append_val (pattern, dash);
+      break;
+
+    case GIMP_DASH_SHORT_DASH:
+      dash = 3.0; g_array_append_val (pattern, dash);
+      dash = 9.0; g_array_append_val (pattern, dash);
+      break;
+
+    case GIMP_DASH_SPARSE_DOTS:
+      for (i = 0; i < 2; i++)
+        {
+          dash = 1.0; g_array_append_val (pattern, dash);
+          dash = 5.0; g_array_append_val (pattern, dash);
+        }
+      break;
+
+    case GIMP_DASH_NORMAL_DOTS:
+      for (i = 0; i < 3; i++)
+        {
+          dash = 1.0; g_array_append_val (pattern, dash);
+          dash = 3.0; g_array_append_val (pattern, dash);
+        }
+      break;
+
+    case GIMP_DASH_DENSE_DOTS:
+      for (i = 0; i < 12; i++)
+        {
+          dash = 1.0; g_array_append_val (pattern, dash);
+        }
+      break;
+
+    case GIMP_DASH_STIPPLES:
+      for (i = 0; i < 24; i++)
+        {
+          dash = 0.5; g_array_append_val (pattern, dash);
+        }
+      break;
+
+    case GIMP_DASH_DASH_DOT:
+      dash = 7.0; g_array_append_val (pattern, dash);
+      dash = 2.0; g_array_append_val (pattern, dash);
+      dash = 1.0; g_array_append_val (pattern, dash);
+      dash = 2.0; g_array_append_val (pattern, dash);
+      break;
+
+    case GIMP_DASH_DASH_DOT_DOT:
+      dash = 7.0; g_array_append_val (pattern, dash);
+      for (i=0; i < 5; i++)
+        {
+          dash = 1.0; g_array_append_val (pattern, dash);
+        }
+      break;
+    }
+
+  if (pattern->len < 2)
+    {
+      gimp_dash_pattern_free (pattern);
+      return NULL;
+    }
+
+  return pattern;
+}
+
+GArray *
+gimp_dash_pattern_new_from_segments (const gboolean *segments,
+                                     gint            n_segments,
+                                     gdouble         dash_length)
+{
+  GArray   *pattern;
+  gint      i;
+  gint      count;
+  gboolean  state;
+
+  g_return_val_if_fail (segments != NULL || n_segments == 0, NULL);
+
+  pattern = g_array_new (FALSE, FALSE, sizeof (gdouble));
+
+  for (i = 0, count = 0, state = TRUE; i <= n_segments; i++)
+    {
+      if (i < n_segments && segments[i] == state)
+        {
+          count++;
+        }
+      else
+        {
+          gdouble l = (dash_length * count) / n_segments;
+
+          g_array_append_val (pattern, l);
+
+          count = 1;
+          state = ! state;
+        }
+    }
+
+  if (pattern->len < 2)
+    {
+      gimp_dash_pattern_free (pattern);
+      return NULL;
+    }
+
+  return pattern;
+}
+
+void
+gimp_dash_pattern_fill_segments (GArray   *pattern,
+                                 gboolean *segments,
+                                 gint      n_segments)
+{
+  gdouble   factor;
+  gdouble   sum;
+  gint      i, j;
+  gboolean  paint;
+
+  g_return_if_fail (segments != NULL || n_segments == 0);
+
+  if (pattern == NULL || pattern->len <= 1)
+    {
+      for (i = 0; i < n_segments; i++)
+        segments[i] = TRUE;
+
+      return;
+    }
+
+  for (i = 0, sum = 0; i < pattern->len ; i++)
+    {
+      sum += g_array_index (pattern, gdouble, i);
+    }
+
+  factor = ((gdouble) n_segments) / sum;
+
+  j = 0;
+  sum = g_array_index (pattern, gdouble, j) * factor;
+  paint = TRUE;
+
+  for (i = 0; i < n_segments ; i++)
+    {
+      while (j < pattern->len && sum <= i)
+        {
+          paint = ! paint;
+          j++;
+          sum += g_array_index (pattern, gdouble, j) * factor;
+        }
+
+      segments[i] = paint;
+    }
+}
+
+GArray *
+gimp_dash_pattern_from_value_array (GimpValueArray *value_array)
+{
+  if (value_array == NULL || gimp_value_array_length (value_array) == 0)
+    {
+      return NULL;
+    }
+  else
+    {
+      GArray *pattern;
+      gint    length;
+      gint    i;
+
+      length = gimp_value_array_length (value_array);
+
+      pattern = g_array_sized_new (FALSE, FALSE, sizeof (gdouble), length);
+
+      for (i = 0; i < length; i++)
+        {
+          GValue *item = gimp_value_array_index (value_array, i);
+          gdouble val;
+
+          g_return_val_if_fail (G_VALUE_HOLDS_DOUBLE (item), NULL);
+
+          val = g_value_get_double (item);
+
+          g_array_append_val (pattern, val);
+        }
+
+      return pattern;
+    }
+}
+
+GimpValueArray *
+gimp_dash_pattern_to_value_array (GArray *pattern)
+{
+  if (pattern != NULL && pattern->len > 0)
+    {
+      GimpValueArray *value_array = gimp_value_array_new (pattern->len);
+      GValue          item        = G_VALUE_INIT;
+      gint            i;
+
+      g_value_init (&item, G_TYPE_DOUBLE);
+
+      for (i = 0; i < pattern->len; i++)
+        {
+          g_value_set_double (&item, g_array_index (pattern, gdouble, i));
+          gimp_value_array_append (value_array, &item);
+        }
+
+      g_value_unset (&item);
+
+      return value_array;
+    }
+
+  return NULL;
+}
+
+GArray *
+gimp_dash_pattern_from_double_array (gint           n_dashes,
+                                     const gdouble *dashes)
+{
+  if (n_dashes > 0 && dashes != NULL)
+    {
+      GArray *pattern;
+      gint    i;
+
+      pattern = g_array_new (FALSE, FALSE, sizeof (gdouble));
+
+      for (i = 0; i < n_dashes; i++)
+        {
+          if (dashes[i] >= 0.0)
+            {
+              g_array_append_val (pattern, dashes[i]);
+            }
+          else
+            {
+              g_array_free (pattern, TRUE);
+              return NULL;
+            }
+        }
+
+      return pattern;
+    }
+
+  return NULL;
+}
+
+gdouble *
+gimp_dash_pattern_to_double_array (GArray *pattern,
+                                   gint   *n_dashes)
+{
+  if (pattern != NULL && pattern->len > 0)
+    {
+      gdouble *dashes;
+      gint     i;
+
+      dashes = g_new0 (gdouble, pattern->len);
+
+      for (i = 0; i < pattern->len; i++)
+        {
+          dashes[i] = g_array_index (pattern, gdouble, i);
+        }
+
+      if (n_dashes)
+        *n_dashes = pattern->len;
+
+      return dashes;
+    }
+
+  return NULL;
+}
+
+GArray *
+gimp_dash_pattern_copy (GArray *pattern)
+{
+  if (pattern)
+    {
+      GArray *copy;
+      gint    i;
+
+      copy = g_array_sized_new (FALSE, FALSE, sizeof (gdouble), pattern->len);
+
+      for (i = 0; i < pattern->len; i++)
+        g_array_append_val (copy, g_array_index (pattern, gdouble, i));
+
+      return copy;
+    }
+
+  return NULL;
+}
+
+void
+gimp_dash_pattern_free (GArray *pattern)
+{
+  if (pattern)
+    g_array_free (pattern, TRUE);
+}
diff --git a/app/core/gimpdashpattern.h b/app/core/gimpdashpattern.h
new file mode 100644
index 0000000..005c516
--- /dev/null
+++ b/app/core/gimpdashpattern.h
@@ -0,0 +1,53 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1999 Spencer Kimball and Peter Mattis
+ *
+ * gimpdashpattern.h
+ * Copyright (C) 2003 Simon Budig
+ * Copyright (C) 2005 Sven Neumann
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_DASH_PATTERN_H__
+#define __GIMP_DASH_PATTERN_H__
+
+
+#define GIMP_TYPE_DASH_PATTERN               (gimp_dash_pattern_get_type ())
+#define GIMP_VALUE_HOLDS_DASH_PATTERN(value) (G_TYPE_CHECK_VALUE_TYPE ((value), GIMP_TYPE_DASH_PATTERN))
+
+
+GType            gimp_dash_pattern_get_type          (void) G_GNUC_CONST;
+
+GArray         * gimp_dash_pattern_new_from_preset   (GimpDashPreset  preset);
+GArray         * gimp_dash_pattern_new_from_segments (const gboolean *segments,
+                                                      gint            n_segments,
+                                                      gdouble         dash_length);
+
+void             gimp_dash_pattern_fill_segments     (GArray         *pattern,
+                                                      gboolean       *segments,
+                                                      gint            n_segments);
+
+GArray         * gimp_dash_pattern_from_value_array  (GimpValueArray *value_array);
+GimpValueArray * gimp_dash_pattern_to_value_array    (GArray         *pattern);
+
+GArray         * gimp_dash_pattern_from_double_array (gint            n_dashes,
+                                                      const gdouble  *dashes);
+gdouble        * gimp_dash_pattern_to_double_array   (GArray         *pattern,
+                                                      gint           *n_dashes);
+
+GArray         * gimp_dash_pattern_copy              (GArray         *pattern);
+void             gimp_dash_pattern_free              (GArray         *pattern);
+
+
+#endif  /*  __GIMP_DASH_PATTERN_H__  */
diff --git a/app/core/gimpdata.c b/app/core/gimpdata.c
new file mode 100644
index 0000000..e4640f3
--- /dev/null
+++ b/app/core/gimpdata.c
@@ -0,0 +1,1245 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpdata.c
+ * Copyright (C) 2001 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+
+#include "core-types.h"
+
+#include "gimp-memsize.h"
+#include "gimpdata.h"
+#include "gimpmarshal.h"
+#include "gimptag.h"
+#include "gimptagged.h"
+
+#include "gimp-intl.h"
+
+
+enum
+{
+  DIRTY,
+  LAST_SIGNAL
+};
+
+enum
+{
+  PROP_0,
+  PROP_FILE,
+  PROP_WRITABLE,
+  PROP_DELETABLE,
+  PROP_MIME_TYPE
+};
+
+
+struct _GimpDataPrivate
+{
+  GFile  *file;
+  GQuark  mime_type;
+  guint   writable  : 1;
+  guint   deletable : 1;
+  guint   dirty     : 1;
+  guint   internal  : 1;
+  gint    freeze_count;
+  gint64  mtime;
+
+  /* Identifies the GimpData object across sessions. Used when there
+   * is not a filename associated with the object.
+   */
+  gchar  *identifier;
+
+  GList  *tags;
+};
+
+#define GIMP_DATA_GET_PRIVATE(obj) (((GimpData *) (obj))->priv)
+
+
+static void       gimp_data_tagged_iface_init (GimpTaggedInterface *iface);
+
+static void       gimp_data_constructed       (GObject             *object);
+static void       gimp_data_finalize          (GObject             *object);
+static void       gimp_data_set_property      (GObject             *object,
+                                               guint                property_id,
+                                               const GValue        *value,
+                                               GParamSpec          *pspec);
+static void       gimp_data_get_property      (GObject             *object,
+                                               guint                property_id,
+                                               GValue              *value,
+                                               GParamSpec          *pspec);
+
+static void       gimp_data_name_changed      (GimpObject          *object);
+static gint64     gimp_data_get_memsize       (GimpObject          *object,
+                                               gint64              *gui_size);
+
+static gboolean   gimp_data_is_name_editable  (GimpViewable        *viewable);
+
+static void       gimp_data_real_dirty        (GimpData            *data);
+static GimpData * gimp_data_real_duplicate    (GimpData            *data);
+static gint       gimp_data_real_compare      (GimpData            *data1,
+                                               GimpData            *data2);
+
+static gboolean   gimp_data_add_tag           (GimpTagged          *tagged,
+                                               GimpTag             *tag);
+static gboolean   gimp_data_remove_tag        (GimpTagged          *tagged,
+                                               GimpTag             *tag);
+static GList    * gimp_data_get_tags          (GimpTagged          *tagged);
+static gchar    * gimp_data_get_identifier    (GimpTagged          *tagged);
+static gchar    * gimp_data_get_checksum      (GimpTagged          *tagged);
+
+
+G_DEFINE_TYPE_WITH_CODE (GimpData, gimp_data, GIMP_TYPE_VIEWABLE,
+                         G_ADD_PRIVATE (GimpData)
+                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_TAGGED,
+                                                gimp_data_tagged_iface_init))
+
+#define parent_class gimp_data_parent_class
+
+static guint data_signals[LAST_SIGNAL] = { 0 };
+
+
+static void
+gimp_data_class_init (GimpDataClass *klass)
+{
+  GObjectClass      *object_class      = G_OBJECT_CLASS (klass);
+  GimpObjectClass   *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+  GimpViewableClass *viewable_class    = GIMP_VIEWABLE_CLASS (klass);
+
+  parent_class = g_type_class_peek_parent (klass);
+
+  data_signals[DIRTY] =
+    g_signal_new ("dirty",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpDataClass, dirty),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  object_class->constructed        = gimp_data_constructed;
+  object_class->finalize           = gimp_data_finalize;
+  object_class->set_property       = gimp_data_set_property;
+  object_class->get_property       = gimp_data_get_property;
+
+  gimp_object_class->name_changed  = gimp_data_name_changed;
+  gimp_object_class->get_memsize   = gimp_data_get_memsize;
+
+  viewable_class->name_editable    = TRUE;
+  viewable_class->is_name_editable = gimp_data_is_name_editable;
+
+  klass->dirty                     = gimp_data_real_dirty;
+  klass->save                      = NULL;
+  klass->get_extension             = NULL;
+  klass->copy                      = NULL;
+  klass->duplicate                 = gimp_data_real_duplicate;
+  klass->compare                   = gimp_data_real_compare;
+
+  g_object_class_install_property (object_class, PROP_FILE,
+                                   g_param_spec_object ("file", NULL, NULL,
+                                                        G_TYPE_FILE,
+                                                        GIMP_PARAM_READWRITE));
+
+  g_object_class_install_property (object_class, PROP_WRITABLE,
+                                   g_param_spec_boolean ("writable", NULL, NULL,
+                                                         FALSE,
+                                                         GIMP_PARAM_READWRITE));
+
+  g_object_class_install_property (object_class, PROP_DELETABLE,
+                                   g_param_spec_boolean ("deletable", NULL, NULL,
+                                                         FALSE,
+                                                         GIMP_PARAM_READWRITE));
+
+  g_object_class_install_property (object_class, PROP_MIME_TYPE,
+                                   g_param_spec_string ("mime-type", NULL, NULL,
+                                                        NULL,
+                                                        GIMP_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT_ONLY));
+}
+
+static void
+gimp_data_tagged_iface_init (GimpTaggedInterface *iface)
+{
+  iface->add_tag        = gimp_data_add_tag;
+  iface->remove_tag     = gimp_data_remove_tag;
+  iface->get_tags       = gimp_data_get_tags;
+  iface->get_identifier = gimp_data_get_identifier;
+  iface->get_checksum   = gimp_data_get_checksum;
+}
+
+static void
+gimp_data_init (GimpData *data)
+{
+  GimpDataPrivate *private = gimp_data_get_instance_private (data);
+
+  data->priv = private;
+
+  private->writable  = TRUE;
+  private->deletable = TRUE;
+  private->dirty     = TRUE;
+
+  /*  freeze the data object during construction  */
+  gimp_data_freeze (data);
+}
+
+static void
+gimp_data_constructed (GObject *object)
+{
+  GimpDataPrivate *private = GIMP_DATA_GET_PRIVATE (object);
+
+  G_OBJECT_CLASS (parent_class)->constructed (object);
+
+  if (! GIMP_DATA_GET_CLASS (object)->save)
+    private->writable = FALSE;
+
+  gimp_data_thaw (GIMP_DATA (object));
+}
+
+static void
+gimp_data_finalize (GObject *object)
+{
+  GimpDataPrivate *private = GIMP_DATA_GET_PRIVATE (object);
+
+  g_clear_object (&private->file);
+
+  if (private->tags)
+    {
+      g_list_free_full (private->tags, (GDestroyNotify) g_object_unref);
+      private->tags = NULL;
+    }
+
+  g_clear_pointer (&private->identifier, g_free);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gimp_data_set_property (GObject      *object,
+                        guint         property_id,
+                        const GValue *value,
+                        GParamSpec   *pspec)
+{
+  GimpData        *data    = GIMP_DATA (object);
+  GimpDataPrivate *private = GIMP_DATA_GET_PRIVATE (data);
+
+  switch (property_id)
+    {
+    case PROP_FILE:
+      gimp_data_set_file (data,
+                          g_value_get_object (value),
+                          private->writable,
+                          private->deletable);
+      break;
+
+    case PROP_WRITABLE:
+      private->writable = g_value_get_boolean (value);
+      break;
+
+    case PROP_DELETABLE:
+      private->deletable = g_value_get_boolean (value);
+      break;
+
+    case PROP_MIME_TYPE:
+      if (g_value_get_string (value))
+        private->mime_type = g_quark_from_string (g_value_get_string (value));
+      else
+        private->mime_type = 0;
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_data_get_property (GObject    *object,
+                        guint       property_id,
+                        GValue     *value,
+                        GParamSpec *pspec)
+{
+  GimpDataPrivate *private = GIMP_DATA_GET_PRIVATE (object);
+
+  switch (property_id)
+    {
+    case PROP_FILE:
+      g_value_set_object (value, private->file);
+      break;
+
+    case PROP_WRITABLE:
+      g_value_set_boolean (value, private->writable);
+      break;
+
+    case PROP_DELETABLE:
+      g_value_set_boolean (value, private->deletable);
+      break;
+
+    case PROP_MIME_TYPE:
+      g_value_set_string (value, g_quark_to_string (private->mime_type));
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_data_name_changed (GimpObject *object)
+{
+  GimpDataPrivate *private = GIMP_DATA_GET_PRIVATE (object);
+
+  private->dirty = TRUE;
+
+  if (GIMP_OBJECT_CLASS (parent_class)->name_changed)
+    GIMP_OBJECT_CLASS (parent_class)->name_changed (object);
+}
+
+static gint64
+gimp_data_get_memsize (GimpObject *object,
+                       gint64     *gui_size)
+{
+  GimpDataPrivate *private = GIMP_DATA_GET_PRIVATE (object);
+  gint64           memsize = 0;
+
+  memsize += gimp_g_object_get_memsize (G_OBJECT (private->file));
+
+  return memsize + GIMP_OBJECT_CLASS (parent_class)->get_memsize (object,
+                                                                  gui_size);
+}
+
+static gboolean
+gimp_data_is_name_editable (GimpViewable *viewable)
+{
+  return gimp_data_is_writable (GIMP_DATA (viewable)) &&
+         ! gimp_data_is_internal (GIMP_DATA (viewable));
+}
+
+static void
+gimp_data_real_dirty (GimpData *data)
+{
+  gimp_viewable_invalidate_preview (GIMP_VIEWABLE (data));
+
+  /* Emit the "name-changed" to signal general dirtiness, our name
+   * changed implementation will also set the "dirty" flag to TRUE.
+   */
+  gimp_object_name_changed (GIMP_OBJECT (data));
+}
+
+static GimpData *
+gimp_data_real_duplicate (GimpData *data)
+{
+  if (GIMP_DATA_GET_CLASS (data)->copy)
+    {
+      GimpData *new = g_object_new (G_OBJECT_TYPE (data), NULL);
+
+      gimp_data_copy (new, data);
+
+      return new;
+    }
+
+  return NULL;
+}
+
+static gint
+gimp_data_real_compare (GimpData *data1,
+                        GimpData *data2)
+{
+  GimpDataPrivate *private1 = GIMP_DATA_GET_PRIVATE (data1);
+  GimpDataPrivate *private2 = GIMP_DATA_GET_PRIVATE (data2);
+
+  /*  move the internal objects (like the FG -> BG) gradient) to the top  */
+  if (private1->internal != private2->internal)
+    return private1->internal ? -1 : 1;
+
+  /*  keep user-deletable objects above system resource files  */
+  if (private1->deletable != private2->deletable)
+    return private1->deletable ? -1 : 1;
+
+  return gimp_object_name_collate ((GimpObject *) data1,
+                                   (GimpObject *) data2);
+}
+
+static gboolean
+gimp_data_add_tag (GimpTagged *tagged,
+                   GimpTag    *tag)
+{
+  GimpDataPrivate *private = GIMP_DATA_GET_PRIVATE (tagged);
+  GList           *list;
+
+  for (list = private->tags; list; list = g_list_next (list))
+    {
+      GimpTag *this = GIMP_TAG (list->data);
+
+      if (gimp_tag_equals (tag, this))
+        return FALSE;
+    }
+
+  private->tags = g_list_prepend (private->tags, g_object_ref (tag));
+
+  return TRUE;
+}
+
+static gboolean
+gimp_data_remove_tag (GimpTagged *tagged,
+                      GimpTag    *tag)
+{
+  GimpDataPrivate *private = GIMP_DATA_GET_PRIVATE (tagged);
+  GList           *list;
+
+  for (list = private->tags; list; list = g_list_next (list))
+    {
+      GimpTag *this = GIMP_TAG (list->data);
+
+      if (gimp_tag_equals (tag, this))
+        {
+          private->tags = g_list_delete_link (private->tags, list);
+          g_object_unref (this);
+          return TRUE;
+        }
+    }
+
+  return FALSE;
+}
+
+static GList *
+gimp_data_get_tags (GimpTagged *tagged)
+{
+  GimpDataPrivate *private = GIMP_DATA_GET_PRIVATE (tagged);
+
+  return private->tags;
+}
+
+static gchar *
+gimp_data_get_identifier (GimpTagged *tagged)
+{
+  GimpDataPrivate *private    = GIMP_DATA_GET_PRIVATE (tagged);
+  gchar           *identifier = NULL;
+
+  if (private->file)
+    {
+      const gchar *data_dir = gimp_data_directory ();
+      const gchar *gimp_dir = gimp_directory ();
+      gchar       *path     = g_file_get_path (private->file);
+      gchar       *tmp;
+
+      if (g_str_has_prefix (path, data_dir))
+        {
+          tmp = g_strconcat ("${gimp_data_dir}",
+                             path + strlen (data_dir),
+                             NULL);
+          identifier = g_filename_to_utf8 (tmp, -1, NULL, NULL, NULL);
+          g_free (tmp);
+        }
+      else if (g_str_has_prefix (path, gimp_dir))
+        {
+          tmp = g_strconcat ("${gimp_dir}",
+                             path + strlen (gimp_dir),
+                             NULL);
+          identifier = g_filename_to_utf8 (tmp, -1, NULL, NULL, NULL);
+          g_free (tmp);
+        }
+      else if (g_str_has_prefix (path, MYPAINT_BRUSHES_DIR))
+        {
+          tmp = g_strconcat ("${mypaint_brushes_dir}",
+                             path + strlen (MYPAINT_BRUSHES_DIR),
+                             NULL);
+          identifier = g_filename_to_utf8 (tmp, -1, NULL, NULL, NULL);
+          g_free (tmp);
+        }
+      else
+        {
+          identifier = g_filename_to_utf8 (path, -1,
+                                           NULL, NULL, NULL);
+        }
+
+      if (! identifier)
+        {
+          g_printerr ("%s: failed to convert '%s' to utf8.\n",
+                      G_STRFUNC, path);
+          identifier = g_strdup (path);
+        }
+
+      g_free (path);
+    }
+  else if (private->internal)
+    {
+      identifier = g_strdup (private->identifier);
+    }
+
+  return identifier;
+}
+
+static gchar *
+gimp_data_get_checksum (GimpTagged *tagged)
+{
+  return NULL;
+}
+
+/**
+ * gimp_data_save:
+ * @data:  object whose contents are to be saved.
+ * @error: return location for errors or %NULL
+ *
+ * Save the object.  If the object is marked as "internal", nothing
+ * happens.  Otherwise, it is saved to disk, using the file name set
+ * by gimp_data_set_file().  If the save is successful, the object is
+ * marked as not dirty.  If not, an error message is returned using
+ * the @error argument.
+ *
+ * Returns: %TRUE if the object is internal or the save is successful.
+ **/
+gboolean
+gimp_data_save (GimpData  *data,
+                GError   **error)
+{
+  GimpDataPrivate *private;
+  gboolean         success = FALSE;
+
+  g_return_val_if_fail (GIMP_IS_DATA (data), FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  private = GIMP_DATA_GET_PRIVATE (data);
+
+  g_return_val_if_fail (private->writable == TRUE, FALSE);
+
+  if (private->internal)
+    {
+      private->dirty = FALSE;
+      return TRUE;
+    }
+
+  g_return_val_if_fail (G_IS_FILE (private->file), FALSE);
+
+  if (GIMP_DATA_GET_CLASS (data)->save)
+    {
+      GOutputStream *output;
+
+      output = G_OUTPUT_STREAM (g_file_replace (private->file,
+                                                NULL, FALSE, G_FILE_CREATE_NONE,
+                                                NULL, error));
+
+      if (output)
+        {
+          success = GIMP_DATA_GET_CLASS (data)->save (data, output, error);
+
+          if (success)
+            {
+              if (! g_output_stream_close (output, NULL, error))
+                {
+                  g_prefix_error (error,
+                                  _("Error saving '%s': "),
+                                  gimp_file_get_utf8_name (private->file));
+                  success = FALSE;
+                }
+            }
+          else
+            {
+              GCancellable *cancellable = g_cancellable_new ();
+
+              g_cancellable_cancel (cancellable);
+              if (error && *error)
+                {
+                  g_prefix_error (error,
+                                  _("Error saving '%s': "),
+                                  gimp_file_get_utf8_name (private->file));
+                }
+              else
+                {
+                  g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_WRITE,
+                               _("Error saving '%s'"),
+                               gimp_file_get_utf8_name (private->file));
+                }
+              g_output_stream_close (output, cancellable, NULL);
+              g_object_unref (cancellable);
+            }
+
+          g_object_unref (output);
+        }
+    }
+
+  if (success)
+    {
+      GFileInfo *info = g_file_query_info (private->file,
+                                           G_FILE_ATTRIBUTE_TIME_MODIFIED,
+                                           G_FILE_QUERY_INFO_NONE,
+                                           NULL, NULL);
+      if (info)
+        {
+          private->mtime =
+            g_file_info_get_attribute_uint64 (info,
+                                              G_FILE_ATTRIBUTE_TIME_MODIFIED);
+          g_object_unref (info);
+        }
+
+      private->dirty = FALSE;
+    }
+
+  return success;
+}
+
+/**
+ * gimp_data_dirty:
+ * @data: a #GimpData object.
+ *
+ * Marks @data as dirty.  Unless the object is frozen, this causes
+ * its preview to be invalidated, and emits a "dirty" signal.  If the
+ * object is frozen, the function has no effect.
+ **/
+void
+gimp_data_dirty (GimpData *data)
+{
+  GimpDataPrivate *private;
+
+  g_return_if_fail (GIMP_IS_DATA (data));
+
+  private = GIMP_DATA_GET_PRIVATE (data);
+
+  if (private->freeze_count == 0)
+    g_signal_emit (data, data_signals[DIRTY], 0);
+}
+
+void
+gimp_data_clean (GimpData *data)
+{
+  GimpDataPrivate *private;
+
+  g_return_if_fail (GIMP_IS_DATA (data));
+
+  private = GIMP_DATA_GET_PRIVATE (data);
+
+  private->dirty = FALSE;
+}
+
+gboolean
+gimp_data_is_dirty (GimpData *data)
+{
+  GimpDataPrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_DATA (data), FALSE);
+
+  private = GIMP_DATA_GET_PRIVATE (data);
+
+  return private->dirty;
+}
+
+/**
+ * gimp_data_freeze:
+ * @data: a #GimpData object.
+ *
+ * Increments the freeze count for the object.  A positive freeze count
+ * prevents the object from being treated as dirty.  Any call to this
+ * function must be followed eventually by a call to gimp_data_thaw().
+ **/
+void
+gimp_data_freeze (GimpData *data)
+{
+  GimpDataPrivate *private;
+
+  g_return_if_fail (GIMP_IS_DATA (data));
+
+  private = GIMP_DATA_GET_PRIVATE (data);
+
+  private->freeze_count++;
+}
+
+/**
+ * gimp_data_thaw:
+ * @data: a #GimpData object.
+ *
+ * Decrements the freeze count for the object.  If the freeze count
+ * drops to zero, the object is marked as dirty, and the "dirty"
+ * signal is emitted.  It is an error to call this function without
+ * having previously called gimp_data_freeze().
+ **/
+void
+gimp_data_thaw (GimpData *data)
+{
+  GimpDataPrivate *private;
+
+  g_return_if_fail (GIMP_IS_DATA (data));
+
+  private = GIMP_DATA_GET_PRIVATE (data);
+
+  g_return_if_fail (private->freeze_count > 0);
+
+  private->freeze_count--;
+
+  if (private->freeze_count == 0)
+    gimp_data_dirty (data);
+}
+
+gboolean
+gimp_data_is_frozen (GimpData *data)
+{
+  GimpDataPrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_DATA (data), FALSE);
+
+  private = GIMP_DATA_GET_PRIVATE (data);
+
+  return private->freeze_count > 0;
+}
+
+/**
+ * gimp_data_delete_from_disk:
+ * @data:  a #GimpData object.
+ * @error: return location for errors or %NULL
+ *
+ * Deletes the object from disk.  If the object is marked as "internal",
+ * nothing happens.  Otherwise, if the file exists whose name has been
+ * set by gimp_data_set_file(), it is deleted.  Obviously this is
+ * a potentially dangerous function, which should be used with care.
+ *
+ * Returns: %TRUE if the object is internal to Gimp, or the deletion is
+ *          successful.
+ **/
+gboolean
+gimp_data_delete_from_disk (GimpData  *data,
+                            GError   **error)
+{
+  GimpDataPrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_DATA (data), FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  private = GIMP_DATA_GET_PRIVATE (data);
+
+  g_return_val_if_fail (private->file      != NULL, FALSE);
+  g_return_val_if_fail (private->deletable == TRUE, FALSE);
+
+  if (private->internal)
+    return TRUE;
+
+  return g_file_delete (private->file, NULL, error);
+}
+
+const gchar *
+gimp_data_get_extension (GimpData *data)
+{
+  g_return_val_if_fail (GIMP_IS_DATA (data), NULL);
+
+  if (GIMP_DATA_GET_CLASS (data)->get_extension)
+    return GIMP_DATA_GET_CLASS (data)->get_extension (data);
+
+  return NULL;
+}
+
+/**
+ * gimp_data_set_file:
+ * @data:     A #GimpData object
+ * @file:     File to assign to @data.
+ * @writable: %TRUE if we want to be able to write to this file.
+ * @deletable: %TRUE if we want to be able to delete this file.
+ *
+ * This function assigns a file to @data, and sets some flags
+ * according to the properties of the file.  If @writable is %TRUE,
+ * and the user has permission to write or overwrite the requested
+ * file name, and a "save" method exists for @data's object type, then
+ * @data is marked as writable.
+ **/
+void
+gimp_data_set_file (GimpData *data,
+                    GFile    *file,
+                    gboolean  writable,
+                    gboolean  deletable)
+{
+  GimpDataPrivate *private;
+  gchar           *path;
+
+  g_return_if_fail (GIMP_IS_DATA (data));
+  g_return_if_fail (G_IS_FILE (file));
+
+  path = g_file_get_path (file);
+
+  g_return_if_fail (path != NULL);
+  g_return_if_fail (g_path_is_absolute (path));
+
+  g_free (path);
+
+  private = GIMP_DATA_GET_PRIVATE (data);
+
+  if (private->internal)
+    return;
+
+  g_set_object (&private->file, file);
+
+  private->writable  = FALSE;
+  private->deletable = FALSE;
+
+  /*  if the data is supposed to be writable or deletable,
+   *  still check if it really is
+   */
+  if (writable || deletable)
+    {
+      GFileInfo *info;
+
+      if (g_file_query_exists (private->file, NULL)) /* check if it exists */
+        {
+          info = g_file_query_info (private->file,
+                                    G_FILE_ATTRIBUTE_ACCESS_CAN_WRITE,
+                                    G_FILE_QUERY_INFO_NONE,
+                                    NULL, NULL);
+
+          /* and we can write it */
+          if (info)
+            {
+              if (g_file_info_get_attribute_boolean (info,
+                                                     G_FILE_ATTRIBUTE_ACCESS_CAN_WRITE))
+                {
+                  private->writable  = writable  ? TRUE : FALSE;
+                  private->deletable = deletable ? TRUE : FALSE;
+                }
+
+              g_object_unref (info);
+            }
+        }
+      else /* OR it doesn't exist */
+        {
+          GFile *parent = g_file_get_parent (private->file);
+
+          info = g_file_query_info (parent,
+                                    G_FILE_ATTRIBUTE_ACCESS_CAN_WRITE,
+                                    G_FILE_QUERY_INFO_NONE,
+                                    NULL, NULL);
+
+          /* and we can write to its parent directory */
+          if (info)
+            {
+              if (g_file_info_get_attribute_boolean (info,
+                                                     G_FILE_ATTRIBUTE_ACCESS_CAN_WRITE))
+                {
+                  private->writable  = writable  ? TRUE : FALSE;
+                  private->deletable = deletable ? TRUE : FALSE;
+                }
+
+              g_object_unref (info);
+            }
+
+          g_object_unref (parent);
+        }
+
+      /*  if we can't save, we are not writable  */
+      if (! GIMP_DATA_GET_CLASS (data)->save)
+        private->writable = FALSE;
+    }
+}
+
+GFile *
+gimp_data_get_file (GimpData *data)
+{
+  GimpDataPrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_DATA (data), NULL);
+
+  private = GIMP_DATA_GET_PRIVATE (data);
+
+  return private->file;
+}
+
+/**
+ * gimp_data_create_filename:
+ * @data:     a #Gimpdata object.
+ * @dest_dir: directory in which to create a file name.
+ *
+ * This function creates a unique file name to be used for saving
+ * a representation of @data in the directory @dest_dir.  If the
+ * user does not have write permission in @dest_dir, then @data
+ * is marked as "not writable", so you should check on this before
+ * assuming that @data can be saved.
+ **/
+void
+gimp_data_create_filename (GimpData *data,
+                           GFile    *dest_dir)
+{
+  GimpDataPrivate *private;
+  gchar           *safename;
+  gchar           *basename;
+  GFile           *file;
+  gint             i;
+  gint             unum  = 1;
+  GError          *error = NULL;
+
+  g_return_if_fail (GIMP_IS_DATA (data));
+  g_return_if_fail (G_IS_FILE (dest_dir));
+
+  private = GIMP_DATA_GET_PRIVATE (data);
+
+  if (private->internal)
+    return;
+
+  safename = g_strstrip (g_strdup (gimp_object_get_name (data)));
+
+  if (safename[0] == '.')
+    safename[0] = '-';
+
+  for (i = 0; safename[i]; i++)
+    if (strchr ("\\/*?\"`'<>{}|\n\t ;:$^&", safename[i]))
+      safename[i] = '-';
+
+  basename = g_strconcat (safename, gimp_data_get_extension (data), NULL);
+
+  file = g_file_get_child_for_display_name (dest_dir, basename, &error);
+  g_free (basename);
+
+  if (! file)
+    {
+      g_warning ("gimp_data_create_filename:\n"
+                 "g_file_get_child_for_display_name() failed for '%s': %s",
+                 gimp_object_get_name (data), error->message);
+      g_clear_error (&error);
+      g_free (safename);
+      return;
+    }
+
+  while (g_file_query_exists (file, NULL))
+    {
+      g_object_unref (file);
+
+      basename = g_strdup_printf ("%s-%d%s",
+                                  safename,
+                                  unum++,
+                                  gimp_data_get_extension (data));
+
+      file = g_file_get_child_for_display_name (dest_dir, basename, NULL);
+      g_free (basename);
+    }
+
+  g_free (safename);
+
+  gimp_data_set_file (data, file, TRUE, TRUE);
+
+  g_object_unref (file);
+}
+
+static const gchar *tag_blacklist[] = { "brushes",
+                                        "dynamics",
+                                        "patterns",
+                                        "palettes",
+                                        "gradients",
+                                        "tool-presets" };
+
+/**
+ * gimp_data_set_folder_tags:
+ * @data:          a #Gimpdata object.
+ * @top_directory: the top directory of the currently processed data
+ *                 hierarchy.
+ *
+ * Sets tags based on all folder names below top_directory. So if the
+ * data's filename is e.g.
+ * /home/foo/.config/GIMP/X.Y/brushes/Flowers/Roses/rose.gbr, it will
+ * add "Flowers" and "Roses" tags.
+ *
+ * if the top directory (as passed, or as derived from the data's
+ * filename) does not end with one of the default data directory names
+ * (brushes, patterns etc), its name will be added as tag too.
+ **/
+void
+gimp_data_set_folder_tags (GimpData *data,
+                           GFile    *top_directory)
+{
+  GimpDataPrivate *private;
+  gchar           *tmp;
+  gchar           *dirname;
+  gchar           *top_path;
+
+  g_return_if_fail (GIMP_IS_DATA (data));
+  g_return_if_fail (G_IS_FILE (top_directory));
+
+  private = GIMP_DATA_GET_PRIVATE (data);
+
+  if (private->internal)
+    return;
+
+  g_return_if_fail (private->file != NULL);
+
+  tmp = g_file_get_path (private->file);
+  dirname = g_path_get_dirname (tmp);
+  g_free (tmp);
+
+  top_path = g_file_get_path (top_directory);
+
+  g_return_if_fail (g_str_has_prefix (dirname, top_path));
+
+  /*  walk up the hierarchy and set each folder on the way as tag,
+   *  except the top_directory
+   */
+  while (strcmp (dirname, top_path))
+    {
+      gchar   *basename = g_path_get_basename (dirname);
+      GimpTag *tag      = gimp_tag_new (basename);
+
+      gimp_tag_set_internal (tag, TRUE);
+      gimp_tagged_add_tag (GIMP_TAGGED (data), tag);
+      g_object_unref (tag);
+      g_free (basename);
+
+      tmp = g_path_get_dirname (dirname);
+      g_free (dirname);
+      dirname = tmp;
+    }
+
+  g_free (top_path);
+
+  if (dirname)
+    {
+      gchar *basename = g_path_get_basename (dirname);
+      gint   i;
+
+      for (i = 0; i <  G_N_ELEMENTS (tag_blacklist); i++)
+        {
+          if (! strcmp (basename, tag_blacklist[i]))
+            break;
+        }
+
+      if (i == G_N_ELEMENTS (tag_blacklist))
+        {
+          GimpTag *tag = gimp_tag_new (basename);
+
+          gimp_tag_set_internal (tag, TRUE);
+          gimp_tagged_add_tag (GIMP_TAGGED (data), tag);
+          g_object_unref (tag);
+        }
+
+      g_free (basename);
+      g_free (dirname);
+    }
+}
+
+const gchar *
+gimp_data_get_mime_type (GimpData *data)
+{
+  GimpDataPrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_DATA (data), NULL);
+
+  private = GIMP_DATA_GET_PRIVATE (data);
+
+  return g_quark_to_string (private->mime_type);
+}
+
+gboolean
+gimp_data_is_writable (GimpData *data)
+{
+  GimpDataPrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_DATA (data), FALSE);
+
+  private = GIMP_DATA_GET_PRIVATE (data);
+
+  return private->writable;
+}
+
+gboolean
+gimp_data_is_deletable (GimpData *data)
+{
+  GimpDataPrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_DATA (data), FALSE);
+
+  private = GIMP_DATA_GET_PRIVATE (data);
+
+  return private->deletable;
+}
+
+void
+gimp_data_set_mtime (GimpData *data,
+                     gint64    mtime)
+{
+  GimpDataPrivate *private;
+
+  g_return_if_fail (GIMP_IS_DATA (data));
+
+  private = GIMP_DATA_GET_PRIVATE (data);
+
+  private->mtime = mtime;
+}
+
+gint64
+gimp_data_get_mtime (GimpData *data)
+{
+  GimpDataPrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_DATA (data), 0);
+
+  private = GIMP_DATA_GET_PRIVATE (data);
+
+  return private->mtime;
+}
+
+gboolean
+gimp_data_is_copyable (GimpData *data)
+{
+  g_return_val_if_fail (GIMP_IS_DATA (data), FALSE);
+
+  return GIMP_DATA_GET_CLASS (data)->copy != NULL;
+}
+
+/**
+ * gimp_data_copy:
+ * @data:     a #GimpData object
+ * @src_data: the #GimpData object to copy from
+ *
+ * Copies @src_data to @data.  Only the object data is  copied:  the
+ * name, file name, preview, etc. are not copied.
+ **/
+void
+gimp_data_copy (GimpData *data,
+                GimpData *src_data)
+{
+  g_return_if_fail (GIMP_IS_DATA (data));
+  g_return_if_fail (GIMP_IS_DATA (src_data));
+  g_return_if_fail (GIMP_DATA_GET_CLASS (data)->copy != NULL);
+  g_return_if_fail (GIMP_DATA_GET_CLASS (data)->copy ==
+                    GIMP_DATA_GET_CLASS (src_data)->copy);
+
+  if (data != src_data)
+    GIMP_DATA_GET_CLASS (data)->copy (data, src_data);
+}
+
+gboolean
+gimp_data_is_duplicatable (GimpData *data)
+{
+  g_return_val_if_fail (GIMP_IS_DATA (data), FALSE);
+
+  if (GIMP_DATA_GET_CLASS (data)->duplicate == gimp_data_real_duplicate)
+    return gimp_data_is_copyable (data);
+  else
+    return GIMP_DATA_GET_CLASS (data)->duplicate != NULL;
+}
+
+/**
+ * gimp_data_duplicate:
+ * @data: a #GimpData object
+ *
+ * Creates a copy of @data, if possible.  Only the object data is
+ * copied:  the newly created object is not automatically given an
+ * object name, file name, preview, etc.
+ *
+ * Returns: the newly created copy, or %NULL if @data cannot be copied.
+ **/
+GimpData *
+gimp_data_duplicate (GimpData *data)
+{
+  g_return_val_if_fail (GIMP_IS_DATA (data), NULL);
+
+  if (gimp_data_is_duplicatable (data))
+    {
+      GimpData        *new     = GIMP_DATA_GET_CLASS (data)->duplicate (data);
+      GimpDataPrivate *private = GIMP_DATA_GET_PRIVATE (new);
+
+      g_object_set (new,
+                    "name",      NULL,
+                    "writable",  GIMP_DATA_GET_CLASS (new)->save != NULL,
+                    "deletable", TRUE,
+                    NULL);
+
+      g_clear_object (&private->file);
+
+      return new;
+    }
+
+  return NULL;
+}
+
+/**
+ * gimp_data_make_internal:
+ * @data: a #GimpData object.
+ *
+ * Mark @data as "internal" to Gimp, which means that it will not be
+ * saved to disk.  Note that if you do this, later calls to
+ * gimp_data_save() and gimp_data_delete_from_disk() will
+ * automatically return successfully without giving any warning.
+ *
+ * The identifier name shall be an untranslated globally unique string
+ * that identifies the internal object across sessions.
+ **/
+void
+gimp_data_make_internal (GimpData    *data,
+                         const gchar *identifier)
+{
+  GimpDataPrivate *private;
+
+  g_return_if_fail (GIMP_IS_DATA (data));
+
+  private = GIMP_DATA_GET_PRIVATE (data);
+
+  g_clear_object (&private->file);
+
+  g_free (private->identifier);
+  private->identifier = g_strdup (identifier);
+
+  private->writable  = FALSE;
+  private->deletable = FALSE;
+  private->internal  = TRUE;
+}
+
+gboolean
+gimp_data_is_internal (GimpData *data)
+{
+  GimpDataPrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_DATA (data), FALSE);
+
+  private = GIMP_DATA_GET_PRIVATE (data);
+
+  return private->internal;
+}
+
+/**
+ * gimp_data_compare:
+ * @data1: a #GimpData object.
+ * @data2: another #GimpData object.
+ *
+ * Compares two data objects for use in sorting. Objects marked as
+ * "internal" come first, then user-writable objects, then system data
+ * files. In these three groups, the objects are sorted alphabetically
+ * by name, using gimp_object_name_collate().
+ *
+ * Return value: -1 if @data1 compares before @data2,
+ *                0 if they compare equal,
+ *                1 if @data1 compares after @data2.
+ **/
+gint
+gimp_data_compare (GimpData *data1,
+                   GimpData *data2)
+{
+  g_return_val_if_fail (GIMP_IS_DATA (data1), 0);
+  g_return_val_if_fail (GIMP_IS_DATA (data2), 0);
+  g_return_val_if_fail (GIMP_DATA_GET_CLASS (data1)->compare ==
+                        GIMP_DATA_GET_CLASS (data2)->compare, 0);
+
+  return GIMP_DATA_GET_CLASS (data1)->compare (data1, data2);
+}
+
+/**
+ * gimp_data_error_quark:
+ *
+ * This function is used to implement the GIMP_DATA_ERROR macro. It
+ * shouldn't be called directly.
+ *
+ * Return value: the #GQuark to identify error in the GimpData error domain.
+ **/
+GQuark
+gimp_data_error_quark (void)
+{
+  return g_quark_from_static_string ("gimp-data-error-quark");
+}
diff --git a/app/core/gimpdata.h b/app/core/gimpdata.h
new file mode 100644
index 0000000..44cd26c
--- /dev/null
+++ b/app/core/gimpdata.h
@@ -0,0 +1,133 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpdata.h
+ * Copyright (C) 2001 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_DATA_H__
+#define __GIMP_DATA_H__
+
+
+#include "gimpviewable.h"
+
+
+typedef enum
+{
+  GIMP_DATA_ERROR_OPEN,   /*  opening data file failed   */
+  GIMP_DATA_ERROR_READ,   /*  reading data file failed   */
+  GIMP_DATA_ERROR_WRITE,  /*  writing data file failed   */
+  GIMP_DATA_ERROR_DELETE  /*  deleting data file failed  */
+} GimpDataError;
+
+
+#define GIMP_TYPE_DATA            (gimp_data_get_type ())
+#define GIMP_DATA(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_DATA, GimpData))
+#define GIMP_DATA_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_DATA, GimpDataClass))
+#define GIMP_IS_DATA(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_DATA))
+#define GIMP_IS_DATA_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_DATA))
+#define GIMP_DATA_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_DATA, GimpDataClass))
+
+
+typedef struct _GimpDataPrivate GimpDataPrivate;
+typedef struct _GimpDataClass   GimpDataClass;
+
+struct _GimpData
+{
+  GimpViewable     parent_instance;
+
+  GimpDataPrivate *priv;
+};
+
+struct _GimpDataClass
+{
+  GimpViewableClass  parent_class;
+
+  /*  signals  */
+  void          (* dirty)         (GimpData  *data);
+
+  /*  virtual functions  */
+  gboolean      (* save)          (GimpData       *data,
+                                   GOutputStream  *output,
+                                   GError        **error);
+  const gchar * (* get_extension) (GimpData       *data);
+  void          (* copy)          (GimpData       *data,
+                                   GimpData       *src_data);
+  GimpData    * (* duplicate)     (GimpData       *data);
+  gint          (* compare)       (GimpData       *data1,
+                                   GimpData       *data2);
+};
+
+
+GType         gimp_data_get_type         (void) G_GNUC_CONST;
+
+gboolean      gimp_data_save             (GimpData     *data,
+                                          GError      **error);
+
+void          gimp_data_dirty            (GimpData     *data);
+void          gimp_data_clean            (GimpData     *data);
+gboolean      gimp_data_is_dirty         (GimpData     *data);
+
+void          gimp_data_freeze           (GimpData     *data);
+void          gimp_data_thaw             (GimpData     *data);
+gboolean      gimp_data_is_frozen        (GimpData     *data);
+
+gboolean      gimp_data_delete_from_disk (GimpData     *data,
+                                          GError      **error);
+
+const gchar * gimp_data_get_extension    (GimpData     *data);
+
+void          gimp_data_set_file         (GimpData     *data,
+                                          GFile        *file,
+                                          gboolean      writable,
+                                          gboolean      deletable);
+GFile       * gimp_data_get_file         (GimpData     *data);
+
+void          gimp_data_create_filename  (GimpData     *data,
+                                          GFile        *dest_dir);
+
+void          gimp_data_set_folder_tags  (GimpData     *data,
+                                          GFile        *top_directory);
+
+const gchar * gimp_data_get_mime_type    (GimpData     *data);
+
+gboolean      gimp_data_is_writable      (GimpData     *data);
+gboolean      gimp_data_is_deletable     (GimpData     *data);
+
+void          gimp_data_set_mtime        (GimpData     *data,
+                                          gint64        mtime);
+gint64        gimp_data_get_mtime        (GimpData     *data);
+
+gboolean      gimp_data_is_copyable      (GimpData     *data);
+void          gimp_data_copy             (GimpData     *data,
+                                          GimpData     *src_data);
+
+gboolean      gimp_data_is_duplicatable  (GimpData     *data);
+GimpData    * gimp_data_duplicate        (GimpData     *data);
+
+void          gimp_data_make_internal    (GimpData     *data,
+                                          const gchar  *identifier);
+gboolean      gimp_data_is_internal      (GimpData     *data);
+
+gint          gimp_data_compare          (GimpData     *data1,
+                                          GimpData     *data2);
+
+#define GIMP_DATA_ERROR (gimp_data_error_quark ())
+
+GQuark        gimp_data_error_quark      (void) G_GNUC_CONST;
+
+
+#endif /* __GIMP_DATA_H__ */
diff --git a/app/core/gimpdatafactory.c b/app/core/gimpdatafactory.c
new file mode 100644
index 0000000..5ee7114
--- /dev/null
+++ b/app/core/gimpdatafactory.c
@@ -0,0 +1,945 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpdatafactory.c
+ * Copyright (C) 2001-2018 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+#include <stdlib.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpmath/gimpmath.h"
+#include "libgimpconfig/gimpconfig.h"
+
+#include "core-types.h"
+
+#include "gimp.h"
+#include "gimp-utils.h"
+#include "gimpasyncset.h"
+#include "gimpcancelable.h"
+#include "gimpcontext.h"
+#include "gimpdata.h"
+#include "gimpdatafactory.h"
+#include "gimplist.h"
+#include "gimpuncancelablewaitable.h"
+#include "gimpwaitable.h"
+
+#include "gimp-intl.h"
+
+
+enum
+{
+  PROP_0,
+  PROP_GIMP,
+  PROP_DATA_TYPE,
+  PROP_PATH_PROPERTY_NAME,
+  PROP_WRITABLE_PROPERTY_NAME,
+  PROP_NEW_FUNC,
+  PROP_GET_STANDARD_FUNC
+};
+
+
+struct _GimpDataFactoryPrivate
+{
+  Gimp                    *gimp;
+
+  GType                    data_type;
+  GimpContainer           *container;
+  GimpContainer           *container_obsolete;
+
+  gchar                   *path_property_name;
+  gchar                   *writable_property_name;
+
+  GimpDataNewFunc          data_new_func;
+  GimpDataGetStandardFunc  data_get_standard_func;
+
+  GimpAsyncSet            *async_set;
+};
+
+#define GET_PRIVATE(obj) (((GimpDataFactory *) (obj))->priv)
+
+
+static void       gimp_data_factory_constructed         (GObject             *object);
+static void       gimp_data_factory_set_property        (GObject             *object,
+                                                         guint                property_id,
+                                                         const GValue        *value,
+                                                         GParamSpec          *pspec);
+static void       gimp_data_factory_get_property        (GObject             *object,
+                                                         guint                property_id,
+                                                         GValue              *value,
+                                                         GParamSpec          *pspec);
+static void       gimp_data_factory_finalize            (GObject             *object);
+
+static gint64     gimp_data_factory_get_memsize         (GimpObject          *object,
+                                                         gint64              *gui_size);
+
+static void       gimp_data_factory_real_data_save      (GimpDataFactory     *factory);
+static void       gimp_data_factory_real_data_cancel    (GimpDataFactory     *factory);
+static GimpData * gimp_data_factory_real_data_duplicate (GimpDataFactory     *factory,
+                                                         GimpData            *data);
+static gboolean   gimp_data_factory_real_data_delete    (GimpDataFactory     *factory,
+                                                         GimpData            *data,
+                                                         gboolean             delete_from_disk,
+                                                         GError             **error);
+
+static void       gimp_data_factory_path_notify         (GObject             *object,
+                                                         const GParamSpec    *pspec,
+                                                         GimpDataFactory     *factory);
+static GFile    * gimp_data_factory_get_save_dir        (GimpDataFactory     *factory,
+                                                         GError             **error);
+
+
+G_DEFINE_ABSTRACT_TYPE_WITH_PRIVATE (GimpDataFactory, gimp_data_factory,
+                                     GIMP_TYPE_OBJECT)
+
+#define parent_class gimp_data_factory_parent_class
+
+
+static void
+gimp_data_factory_class_init (GimpDataFactoryClass *klass)
+{
+  GObjectClass    *object_class      = G_OBJECT_CLASS (klass);
+  GimpObjectClass *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+
+  object_class->constructed      = gimp_data_factory_constructed;
+  object_class->set_property     = gimp_data_factory_set_property;
+  object_class->get_property     = gimp_data_factory_get_property;
+  object_class->finalize         = gimp_data_factory_finalize;
+
+  gimp_object_class->get_memsize = gimp_data_factory_get_memsize;
+
+  klass->data_init               = NULL;
+  klass->data_refresh            = NULL;
+  klass->data_save               = gimp_data_factory_real_data_save;
+  klass->data_cancel             = gimp_data_factory_real_data_cancel;
+  klass->data_duplicate          = gimp_data_factory_real_data_duplicate;
+  klass->data_delete             = gimp_data_factory_real_data_delete;
+
+  g_object_class_install_property (object_class, PROP_GIMP,
+                                   g_param_spec_object ("gimp", NULL, NULL,
+                                                        GIMP_TYPE_GIMP,
+                                                        GIMP_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT_ONLY));
+
+  g_object_class_install_property (object_class, PROP_DATA_TYPE,
+                                   g_param_spec_gtype ("data-type", NULL, NULL,
+                                                       GIMP_TYPE_DATA,
+                                                       GIMP_PARAM_READWRITE |
+                                                       G_PARAM_CONSTRUCT_ONLY));
+
+  g_object_class_install_property (object_class, PROP_PATH_PROPERTY_NAME,
+                                   g_param_spec_string ("path-property-name",
+                                                        NULL, NULL,
+                                                        NULL,
+                                                        GIMP_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT_ONLY));
+
+  g_object_class_install_property (object_class, PROP_WRITABLE_PROPERTY_NAME,
+                                   g_param_spec_string ("writable-property-name",
+                                                        NULL, NULL,
+                                                        NULL,
+                                                        GIMP_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT_ONLY));
+
+  g_object_class_install_property (object_class, PROP_NEW_FUNC,
+                                   g_param_spec_pointer ("new-func",
+                                                         NULL, NULL,
+                                                         GIMP_PARAM_READWRITE |
+                                                         G_PARAM_CONSTRUCT_ONLY));
+
+  g_object_class_install_property (object_class, PROP_GET_STANDARD_FUNC,
+                                   g_param_spec_pointer ("get-standard-func",
+                                                         NULL, NULL,
+                                                         GIMP_PARAM_READWRITE |
+                                                         G_PARAM_CONSTRUCT_ONLY));
+}
+
+static void
+gimp_data_factory_init (GimpDataFactory *factory)
+{
+  factory->priv = gimp_data_factory_get_instance_private (factory);
+
+  factory->priv->async_set = gimp_async_set_new ();
+}
+
+static void
+gimp_data_factory_constructed (GObject *object)
+{
+  GimpDataFactoryPrivate *priv = GET_PRIVATE (object);
+
+  G_OBJECT_CLASS (parent_class)->constructed (object);
+
+  gimp_assert (GIMP_IS_GIMP (priv->gimp));
+  gimp_assert (g_type_is_a (priv->data_type, GIMP_TYPE_DATA));
+  gimp_assert (GIMP_DATA_FACTORY_GET_CLASS (object)->data_init != NULL);
+  gimp_assert (GIMP_DATA_FACTORY_GET_CLASS (object)->data_refresh != NULL);
+
+  priv->container = gimp_list_new (priv->data_type, TRUE);
+  gimp_list_set_sort_func (GIMP_LIST (priv->container),
+                           (GCompareFunc) gimp_data_compare);
+
+  priv->container_obsolete = gimp_list_new (priv->data_type, TRUE);
+  gimp_list_set_sort_func (GIMP_LIST (priv->container_obsolete),
+                           (GCompareFunc) gimp_data_compare);
+}
+
+static void
+gimp_data_factory_set_property (GObject      *object,
+                                guint         property_id,
+                                const GValue *value,
+                                GParamSpec   *pspec)
+{
+  GimpDataFactoryPrivate *priv = GET_PRIVATE (object);
+
+  switch (property_id)
+    {
+    case PROP_GIMP:
+      priv->gimp = g_value_get_object (value); /* don't ref */
+      break;
+
+    case PROP_DATA_TYPE:
+      priv->data_type = g_value_get_gtype (value);
+      break;
+
+    case PROP_PATH_PROPERTY_NAME:
+      priv->path_property_name = g_value_dup_string (value);
+      break;
+
+    case PROP_WRITABLE_PROPERTY_NAME:
+      priv->writable_property_name = g_value_dup_string (value);
+      break;
+
+    case PROP_NEW_FUNC:
+      priv->data_new_func = g_value_get_pointer (value);
+      break;
+
+    case PROP_GET_STANDARD_FUNC:
+      priv->data_get_standard_func = g_value_get_pointer (value);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_data_factory_get_property (GObject    *object,
+                                guint       property_id,
+                                GValue     *value,
+                                GParamSpec *pspec)
+{
+  GimpDataFactoryPrivate *priv = GET_PRIVATE (object);
+
+  switch (property_id)
+    {
+    case PROP_GIMP:
+      g_value_set_object (value, priv->gimp);
+      break;
+
+    case PROP_DATA_TYPE:
+      g_value_set_gtype (value, priv->data_type);
+      break;
+
+    case PROP_PATH_PROPERTY_NAME:
+      g_value_set_string (value, priv->path_property_name);
+      break;
+
+    case PROP_WRITABLE_PROPERTY_NAME:
+      g_value_set_string (value, priv->writable_property_name);
+      break;
+
+    case PROP_NEW_FUNC:
+      g_value_set_pointer (value, priv->data_new_func);
+      break;
+
+    case PROP_GET_STANDARD_FUNC:
+      g_value_set_pointer (value, priv->data_get_standard_func);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_data_factory_finalize (GObject *object)
+{
+  GimpDataFactory        *factory = GIMP_DATA_FACTORY (object);
+  GimpDataFactoryPrivate *priv    = GET_PRIVATE (object);
+
+  if (priv->async_set)
+    {
+      gimp_data_factory_data_cancel (factory);
+
+      g_clear_object (&priv->async_set);
+    }
+
+  g_clear_object (&priv->container);
+  g_clear_object (&priv->container_obsolete);
+
+  g_clear_pointer (&priv->path_property_name,     g_free);
+  g_clear_pointer (&priv->writable_property_name, g_free);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static gint64
+gimp_data_factory_get_memsize (GimpObject *object,
+                               gint64     *gui_size)
+{
+  GimpDataFactoryPrivate *priv    = GET_PRIVATE (object);
+  gint64                  memsize = 0;
+
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (priv->container),
+                                      gui_size);
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (priv->container_obsolete),
+                                      gui_size);
+
+  return memsize + GIMP_OBJECT_CLASS (parent_class)->get_memsize (object,
+                                                                  gui_size);
+}
+
+static void
+gimp_data_factory_real_data_save (GimpDataFactory *factory)
+{
+  GimpDataFactoryPrivate *priv = GET_PRIVATE (factory);
+  GList                  *dirty = NULL;
+  GList                  *list;
+  GFile                  *writable_dir;
+  GError                 *error = NULL;
+
+  for (list = GIMP_LIST (priv->container)->queue->head;
+       list;
+       list = g_list_next (list))
+    {
+      GimpData *data = list->data;
+
+      if (gimp_data_is_dirty (data) &&
+          gimp_data_is_writable (data))
+        {
+          dirty = g_list_prepend (dirty, data);
+        }
+    }
+
+  if (! dirty)
+    return;
+
+  writable_dir = gimp_data_factory_get_save_dir (factory, &error);
+
+  if (! writable_dir)
+    {
+      gimp_message (priv->gimp, NULL, GIMP_MESSAGE_ERROR,
+                    _("Failed to save data:\n\n%s"),
+                    error->message);
+      g_clear_error (&error);
+
+      g_list_free (dirty);
+
+      return;
+    }
+
+  for (list = dirty; list; list = g_list_next (list))
+    {
+      GimpData *data  = list->data;
+      GError   *error = NULL;
+
+      if (! gimp_data_get_file (data))
+        gimp_data_create_filename (data, writable_dir);
+
+      if (factory->priv->gimp->be_verbose)
+        {
+          GFile *file = gimp_data_get_file (data);
+
+          if (file)
+            g_print ("Writing dirty data '%s'\n",
+                     gimp_file_get_utf8_name (file));
+        }
+
+      if (! gimp_data_save (data, &error))
+        {
+          /*  check if there actually was an error (no error
+           *  means the data class does not implement save)
+           */
+          if (error)
+            {
+              gimp_message (priv->gimp, NULL, GIMP_MESSAGE_ERROR,
+                            _("Failed to save data:\n\n%s"),
+                            error->message);
+              g_clear_error (&error);
+            }
+        }
+    }
+
+  g_object_unref (writable_dir);
+
+  g_list_free (dirty);
+}
+
+static void
+gimp_data_factory_real_data_cancel (GimpDataFactory *factory)
+{
+  GimpDataFactoryPrivate *priv = GET_PRIVATE (factory);
+
+  gimp_cancelable_cancel (GIMP_CANCELABLE (priv->async_set));
+  gimp_waitable_wait     (GIMP_WAITABLE   (priv->async_set));
+}
+
+static GimpData *
+gimp_data_factory_real_data_duplicate (GimpDataFactory *factory,
+                                       GimpData        *data)
+{
+  GimpDataFactoryPrivate *priv = GET_PRIVATE (factory);
+  GimpData               *new_data;
+
+  new_data = gimp_data_duplicate (data);
+
+  if (new_data)
+    {
+      const gchar *name = gimp_object_get_name (data);
+      gchar       *ext;
+      gint         copy_len;
+      gint         number;
+      gchar       *new_name;
+
+      ext      = strrchr (name, '#');
+      copy_len = strlen (_("copy"));
+
+      if ((strlen (name) >= copy_len                                 &&
+           strcmp (&name[strlen (name) - copy_len], _("copy")) == 0) ||
+          (ext && (number = atoi (ext + 1)) > 0                      &&
+           ((gint) (log10 (number) + 1)) == strlen (ext + 1)))
+        {
+          /* don't have redundant "copy"s */
+          new_name = g_strdup (name);
+        }
+      else
+        {
+          new_name = g_strdup_printf (_("%s copy"), name);
+        }
+
+      gimp_object_take_name (GIMP_OBJECT (new_data), new_name);
+
+      gimp_container_add (priv->container, GIMP_OBJECT (new_data));
+      g_object_unref (new_data);
+    }
+
+  return new_data;
+}
+
+static gboolean
+gimp_data_factory_real_data_delete (GimpDataFactory  *factory,
+                                    GimpData         *data,
+                                    gboolean          delete_from_disk,
+                                    GError          **error)
+{
+  if (delete_from_disk && gimp_data_get_file (data))
+    return gimp_data_delete_from_disk (data, error);
+
+  return TRUE;
+}
+
+
+/*  public functions  */
+
+void
+gimp_data_factory_data_init (GimpDataFactory *factory,
+                             GimpContext     *context,
+                             gboolean         no_data)
+{
+  GimpDataFactoryPrivate *priv = GET_PRIVATE (factory);
+  gchar                  *signal_name;
+
+  g_return_if_fail (GIMP_IS_DATA_FACTORY (factory));
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  /*  Always freeze() and thaw() the container around initialization,
+   *  even if no_data, the thaw() will implicitly make GimpContext
+   *  create the standard data that serves as fallback.
+   */
+  gimp_container_freeze (priv->container);
+
+  if (! no_data)
+    {
+      if (priv->gimp->be_verbose)
+        {
+          const gchar *name = gimp_object_get_name (factory);
+
+          g_print ("Loading '%s' data\n", name ? name : "???");
+        }
+
+      GIMP_DATA_FACTORY_GET_CLASS (factory)->data_init (factory, context);
+    }
+
+  gimp_container_thaw (priv->container);
+
+  signal_name = g_strdup_printf ("notify::%s", priv->path_property_name);
+  g_signal_connect_object (priv->gimp->config, signal_name,
+                           G_CALLBACK (gimp_data_factory_path_notify),
+                           factory, 0);
+  g_free (signal_name);
+}
+
+static void
+gimp_data_factory_clean_cb (GimpDataFactory *factory,
+                            GimpData        *data,
+                            gpointer         user_data)
+{
+  if (gimp_data_is_dirty (data))
+    gimp_data_clean (data);
+}
+
+void
+gimp_data_factory_data_clean (GimpDataFactory *factory)
+{
+  g_return_if_fail (GIMP_IS_DATA_FACTORY (factory));
+
+  gimp_data_factory_data_foreach (factory, TRUE,
+                                  gimp_data_factory_clean_cb, NULL);
+}
+
+void
+gimp_data_factory_data_refresh (GimpDataFactory *factory,
+                                GimpContext     *context)
+{
+  g_return_if_fail (GIMP_IS_DATA_FACTORY (factory));
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  GIMP_DATA_FACTORY_GET_CLASS (factory)->data_refresh (factory, context);
+}
+
+void
+gimp_data_factory_data_save (GimpDataFactory *factory)
+{
+  g_return_if_fail (GIMP_IS_DATA_FACTORY (factory));
+
+  if (! gimp_container_is_empty (factory->priv->container))
+    GIMP_DATA_FACTORY_GET_CLASS (factory)->data_save (factory);
+}
+
+static void
+gimp_data_factory_data_free_foreach (GimpDataFactory *factory,
+                                     GimpData        *data,
+                                     gpointer         user_data)
+{
+  gimp_container_remove (factory->priv->container, GIMP_OBJECT (data));
+}
+
+void
+gimp_data_factory_data_free (GimpDataFactory *factory)
+{
+  g_return_if_fail (GIMP_IS_DATA_FACTORY (factory));
+
+  gimp_data_factory_data_cancel (factory);
+
+  if (! gimp_container_is_empty (factory->priv->container))
+    {
+      gimp_container_freeze (factory->priv->container);
+
+      gimp_data_factory_data_foreach (factory, TRUE,
+                                      gimp_data_factory_data_free_foreach,
+                                      NULL);
+
+      gimp_container_thaw (factory->priv->container);
+    }
+}
+
+GimpAsyncSet *
+gimp_data_factory_get_async_set (GimpDataFactory *factory)
+{
+  g_return_val_if_fail (GIMP_IS_DATA_FACTORY (factory), NULL);
+
+  return factory->priv->async_set;
+}
+
+gboolean
+gimp_data_factory_data_wait (GimpDataFactory *factory)
+{
+  GimpDataFactoryPrivate *priv;
+  GimpWaitable           *waitable;
+
+  g_return_val_if_fail (GIMP_IS_DATA_FACTORY (factory), FALSE);
+
+  priv = GET_PRIVATE (factory);
+
+  /* don't allow cancellation for now */
+  waitable = gimp_uncancelable_waitable_new (GIMP_WAITABLE (priv->async_set));
+
+  gimp_wait (priv->gimp, waitable,
+             _("Loading fonts (this may take a while...)"));
+
+  g_object_unref (waitable);
+
+  return TRUE;
+}
+
+void
+gimp_data_factory_data_cancel (GimpDataFactory *factory)
+{
+  g_return_if_fail (GIMP_IS_DATA_FACTORY (factory));
+
+  GIMP_DATA_FACTORY_GET_CLASS (factory)->data_cancel (factory);
+}
+
+gboolean
+gimp_data_factory_has_data_new_func (GimpDataFactory *factory)
+{
+  g_return_val_if_fail (GIMP_IS_DATA_FACTORY (factory), FALSE);
+
+  return factory->priv->data_new_func != NULL;
+}
+
+GimpData *
+gimp_data_factory_data_new (GimpDataFactory *factory,
+                            GimpContext     *context,
+                            const gchar     *name)
+{
+  GimpDataFactoryPrivate *priv;
+
+  g_return_val_if_fail (GIMP_IS_DATA_FACTORY (factory), NULL);
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+  g_return_val_if_fail (name != NULL, NULL);
+  g_return_val_if_fail (*name != '\0', NULL);
+
+  priv = GET_PRIVATE (factory);
+
+  if (priv->data_new_func)
+    {
+      GimpData *data = priv->data_new_func (context, name);
+
+      if (data)
+        {
+          gimp_container_add (priv->container, GIMP_OBJECT (data));
+          g_object_unref (data);
+
+          return data;
+        }
+
+      g_warning ("%s: GimpDataFactory::data_new_func() returned NULL",
+                 G_STRFUNC);
+    }
+
+  return NULL;
+}
+
+GimpData *
+gimp_data_factory_data_get_standard (GimpDataFactory *factory,
+                                     GimpContext     *context)
+{
+  g_return_val_if_fail (GIMP_IS_DATA_FACTORY (factory), NULL);
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+
+  if (factory->priv->data_get_standard_func)
+    return factory->priv->data_get_standard_func (context);
+
+  return NULL;
+}
+
+GimpData *
+gimp_data_factory_data_duplicate (GimpDataFactory *factory,
+                                  GimpData        *data)
+{
+  g_return_val_if_fail (GIMP_IS_DATA_FACTORY (factory), NULL);
+  g_return_val_if_fail (GIMP_IS_DATA (data), NULL);
+
+  return GIMP_DATA_FACTORY_GET_CLASS (factory)->data_duplicate (factory, data);
+}
+
+gboolean
+gimp_data_factory_data_delete (GimpDataFactory  *factory,
+                               GimpData         *data,
+                               gboolean          delete_from_disk,
+                               GError          **error)
+{
+  GimpDataFactoryPrivate *priv;
+  gboolean                retval = TRUE;
+
+  g_return_val_if_fail (GIMP_IS_DATA_FACTORY (factory), FALSE);
+  g_return_val_if_fail (GIMP_IS_DATA (data), FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  priv = GET_PRIVATE (factory);
+
+  if (gimp_container_have (priv->container, GIMP_OBJECT (data)))
+    {
+      g_object_ref (data);
+
+      gimp_container_remove (priv->container, GIMP_OBJECT (data));
+
+      retval = GIMP_DATA_FACTORY_GET_CLASS (factory)->data_delete (factory, data,
+                                                                   delete_from_disk,
+                                                                   error);
+
+      g_object_unref (data);
+    }
+
+  return retval;
+}
+
+gboolean
+gimp_data_factory_data_save_single (GimpDataFactory  *factory,
+                                    GimpData         *data,
+                                    GError          **error)
+{
+  g_return_val_if_fail (GIMP_IS_DATA_FACTORY (factory), FALSE);
+  g_return_val_if_fail (GIMP_IS_DATA (data), FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  if (! gimp_data_is_dirty (data))
+    return TRUE;
+
+  if (! gimp_data_get_file (data))
+    {
+      GFile  *writable_dir;
+      GError *my_error = NULL;
+
+      writable_dir = gimp_data_factory_get_save_dir (factory, &my_error);
+
+      if (! writable_dir)
+        {
+          g_set_error (error, GIMP_DATA_ERROR, 0,
+                       _("Failed to save data:\n\n%s"),
+                       my_error->message);
+          g_clear_error (&my_error);
+
+          return FALSE;
+        }
+
+      gimp_data_create_filename (data, writable_dir);
+
+      g_object_unref (writable_dir);
+    }
+
+  if (! gimp_data_is_writable (data))
+    return FALSE;
+
+  if (factory->priv->gimp->be_verbose)
+    {
+      GFile *file = gimp_data_get_file (data);
+
+      if (file)
+        g_print ("Writing dirty data '%s'\n",
+                 gimp_file_get_utf8_name (file));
+    }
+
+  if (! gimp_data_save (data, error))
+    {
+      /*  check if there actually was an error (no error
+       *  means the data class does not implement save)
+       */
+      if (! error)
+        g_set_error (error, GIMP_DATA_ERROR, 0,
+                     _("Failed to save data:\n\n%s"),
+                     "Data class does not implement saving");
+
+      return FALSE;
+    }
+
+  return TRUE;
+}
+
+void
+gimp_data_factory_data_foreach (GimpDataFactory     *factory,
+                                gboolean             skip_internal,
+                                GimpDataForeachFunc  callback,
+                                gpointer             user_data)
+{
+  GList *list;
+
+  g_return_if_fail (GIMP_IS_DATA_FACTORY (factory));
+  g_return_if_fail (callback != NULL);
+
+  list = GIMP_LIST (factory->priv->container)->queue->head;
+
+  while (list)
+    {
+      GList *next = g_list_next (list);
+
+      if (! (skip_internal && gimp_data_is_internal (list->data)))
+        callback (factory, list->data, user_data);
+
+      list = next;
+    }
+}
+
+Gimp *
+gimp_data_factory_get_gimp (GimpDataFactory *factory)
+{
+  g_return_val_if_fail (GIMP_IS_DATA_FACTORY (factory), NULL);
+
+  return factory->priv->gimp;
+}
+
+GType
+gimp_data_factory_get_data_type (GimpDataFactory *factory)
+{
+  g_return_val_if_fail (GIMP_IS_DATA_FACTORY (factory), G_TYPE_NONE);
+
+  return gimp_container_get_children_type (factory->priv->container);
+}
+
+GimpContainer *
+gimp_data_factory_get_container (GimpDataFactory *factory)
+{
+  g_return_val_if_fail (GIMP_IS_DATA_FACTORY (factory), NULL);
+
+  return factory->priv->container;
+}
+
+GimpContainer *
+gimp_data_factory_get_container_obsolete (GimpDataFactory *factory)
+{
+  g_return_val_if_fail (GIMP_IS_DATA_FACTORY (factory), NULL);
+
+  return factory->priv->container_obsolete;
+}
+
+GList *
+gimp_data_factory_get_data_path (GimpDataFactory *factory)
+{
+  GimpDataFactoryPrivate *priv = GET_PRIVATE (factory);
+  gchar                  *path = NULL;
+  GList                  *list = NULL;
+
+  g_return_val_if_fail (GIMP_IS_DATA_FACTORY (factory), NULL);
+
+  g_object_get (priv->gimp->config,
+                priv->path_property_name, &path,
+                NULL);
+
+  if (path)
+    {
+      list = gimp_config_path_expand_to_files (path, NULL);
+      g_free (path);
+    }
+
+  return list;
+}
+
+GList *
+gimp_data_factory_get_data_path_writable (GimpDataFactory *factory)
+{
+  GimpDataFactoryPrivate *priv = GET_PRIVATE (factory);
+  gchar                  *path = NULL;
+  GList                  *list = NULL;
+
+  g_return_val_if_fail (GIMP_IS_DATA_FACTORY (factory), NULL);
+
+  g_object_get (priv->gimp->config,
+                priv->writable_property_name, &path,
+                NULL);
+
+  if (path)
+    {
+      list = gimp_config_path_expand_to_files (path, NULL);
+      g_free (path);
+    }
+
+  return list;
+}
+
+
+/*  private functions  */
+
+static void
+gimp_data_factory_path_notify (GObject          *object,
+                               const GParamSpec *pspec,
+                               GimpDataFactory  *factory)
+{
+  GimpDataFactoryPrivate *priv = GET_PRIVATE (factory);
+
+  gimp_set_busy (priv->gimp);
+
+  gimp_data_factory_data_refresh (factory, gimp_get_user_context (priv->gimp));
+
+  gimp_unset_busy (priv->gimp);
+}
+
+static GFile *
+gimp_data_factory_get_save_dir (GimpDataFactory  *factory,
+                                GError          **error)
+{
+  GList *path;
+  GList *writable_path;
+  GFile *writable_dir = NULL;
+
+  path          = gimp_data_factory_get_data_path          (factory);
+  writable_path = gimp_data_factory_get_data_path_writable (factory);
+
+  if (writable_path)
+    {
+      GList    *list;
+      gboolean  found_any = FALSE;
+
+      for (list = writable_path; list; list = g_list_next (list))
+        {
+          GList *found = g_list_find_custom (path, list->data,
+                                             (GCompareFunc) gimp_file_compare);
+          if (found)
+            {
+              GFile *dir = found->data;
+
+              found_any = TRUE;
+
+              if (g_file_query_file_type (dir, G_FILE_QUERY_INFO_NONE,
+                                          NULL) != G_FILE_TYPE_DIRECTORY)
+                {
+                  /*  error out only if this is the last chance  */
+                  if (! list->next)
+                    {
+                      g_set_error (error, GIMP_DATA_ERROR, 0,
+                                   _("You have a writable data folder "
+                                     "configured (%s), but this folder does "
+                                     "not exist. Please create the folder or "
+                                     "fix your configuration in the "
+                                     "Preferences dialog's 'Folders' section."),
+                                   gimp_file_get_utf8_name (dir));
+                    }
+                }
+              else
+                {
+                  writable_dir = g_object_ref (dir);
+                  break;
+                }
+            }
+        }
+
+      if (! writable_dir && ! found_any)
+        {
+          g_set_error (error, GIMP_DATA_ERROR, 0,
+                       _("You have a writable data folder configured, but this "
+                         "folder is not part of your data search path. You "
+                         "probably edited the gimprc file manually, "
+                         "please fix it in the Preferences dialog's 'Folders' "
+                         "section."));
+        }
+    }
+  else
+    {
+      g_set_error (error, GIMP_DATA_ERROR, 0,
+                   _("You don't have any writable data folder configured."));
+    }
+
+  g_list_free_full (path,          (GDestroyNotify) g_object_unref);
+  g_list_free_full (writable_path, (GDestroyNotify) g_object_unref);
+
+  return writable_dir;
+}
diff --git a/app/core/gimpdatafactory.h b/app/core/gimpdatafactory.h
new file mode 100644
index 0000000..47c57ae
--- /dev/null
+++ b/app/core/gimpdatafactory.h
@@ -0,0 +1,125 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpdatafactory.h
+ * Copyright (C) 2001-2018 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_DATA_FACTORY_H__
+#define __GIMP_DATA_FACTORY_H__
+
+
+#include "gimpobject.h"
+
+
+typedef GimpData * (* GimpDataNewFunc)         (GimpContext     *context,
+                                                const gchar     *name);
+typedef GimpData * (* GimpDataGetStandardFunc) (GimpContext     *context);
+
+typedef void       (* GimpDataForeachFunc)     (GimpDataFactory *factory,
+                                                GimpData        *data,
+                                                gpointer         user_data);
+
+
+#define GIMP_TYPE_DATA_FACTORY            (gimp_data_factory_get_type ())
+#define GIMP_DATA_FACTORY(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_DATA_FACTORY, GimpDataFactory))
+#define GIMP_DATA_FACTORY_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_DATA_FACTORY, GimpDataFactoryClass))
+#define GIMP_IS_DATA_FACTORY(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_DATA_FACTORY))
+#define GIMP_IS_DATA_FACTORY_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_DATA_FACTORY))
+#define GIMP_DATA_FACTORY_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_DATA_FACTORY, GimpDataFactoryClass))
+
+
+typedef struct _GimpDataFactoryPrivate GimpDataFactoryPrivate;
+typedef struct _GimpDataFactoryClass   GimpDataFactoryClass;
+
+struct _GimpDataFactory
+{
+  GimpObject              parent_instance;
+
+  GimpDataFactoryPrivate *priv;
+};
+
+struct _GimpDataFactoryClass
+{
+  GimpObjectClass  parent_class;
+
+  void           (* data_init)      (GimpDataFactory *factory,
+                                     GimpContext     *context);
+  void           (* data_refresh)   (GimpDataFactory *factory,
+                                     GimpContext     *context);
+  void           (* data_save)      (GimpDataFactory *factory);
+
+  void           (* data_cancel)    (GimpDataFactory *factory);
+
+  GimpData     * (* data_duplicate) (GimpDataFactory  *factory,
+                                     GimpData         *data);
+  gboolean       (* data_delete)    (GimpDataFactory  *factory,
+                                     GimpData         *data,
+                                     gboolean          delete_from_disk,
+                                     GError          **error);
+};
+
+
+GType           gimp_data_factory_get_type          (void) G_GNUC_CONST;
+
+void            gimp_data_factory_data_init         (GimpDataFactory  *factory,
+                                                     GimpContext      *context,
+                                                     gboolean          no_data);
+void            gimp_data_factory_data_clean        (GimpDataFactory  *factory);
+void            gimp_data_factory_data_refresh      (GimpDataFactory  *factory,
+                                                     GimpContext      *context);
+void            gimp_data_factory_data_save         (GimpDataFactory  *factory);
+void            gimp_data_factory_data_free         (GimpDataFactory  *factory);
+
+GimpAsyncSet  * gimp_data_factory_get_async_set     (GimpDataFactory  *factory);
+gboolean        gimp_data_factory_data_wait         (GimpDataFactory  *factory);
+void            gimp_data_factory_data_cancel       (GimpDataFactory  *factory);
+
+gboolean        gimp_data_factory_has_data_new_func (GimpDataFactory  *factory);
+GimpData      * gimp_data_factory_data_new          (GimpDataFactory  *factory,
+                                                     GimpContext      *context,
+                                                     const gchar      *name);
+GimpData      * gimp_data_factory_data_get_standard (GimpDataFactory  *factory,
+                                                     GimpContext      *context);
+
+GimpData      * gimp_data_factory_data_duplicate    (GimpDataFactory  *factory,
+                                                     GimpData         *data);
+gboolean        gimp_data_factory_data_delete       (GimpDataFactory  *factory,
+                                                     GimpData         *data,
+                                                     gboolean          delete_from_disk,
+                                                     GError          **error);
+
+gboolean        gimp_data_factory_data_save_single  (GimpDataFactory  *factory,
+                                                     GimpData         *data,
+                                                     GError          **error);
+
+void            gimp_data_factory_data_foreach      (GimpDataFactory  *factory,
+                                                     gboolean          skip_internal,
+                                                     GimpDataForeachFunc  callback,
+                                                     gpointer          user_data);
+
+Gimp          * gimp_data_factory_get_gimp          (GimpDataFactory  *factory);
+GType           gimp_data_factory_get_data_type     (GimpDataFactory  *factory);
+GimpContainer * gimp_data_factory_get_container     (GimpDataFactory  *factory);
+GimpContainer * gimp_data_factory_get_container_obsolete
+                                                    (GimpDataFactory  *factory);
+GList         * gimp_data_factory_get_data_path     (GimpDataFactory  *factory);
+GList         * gimp_data_factory_get_data_path_writable
+                                                    (GimpDataFactory  *factory);
+
+
+
+#endif  /*  __GIMP_DATA_FACTORY_H__  */
diff --git a/app/core/gimpdataloaderfactory.c b/app/core/gimpdataloaderfactory.c
new file mode 100644
index 0000000..01c4496
--- /dev/null
+++ b/app/core/gimpdataloaderfactory.c
@@ -0,0 +1,562 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpdataloaderfactory.c
+ * Copyright (C) 2001-2018 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+
+#include "core-types.h"
+
+#include "gimp.h"
+#include "gimp-utils.h"
+#include "gimpcontainer.h"
+#include "gimpdata.h"
+#include "gimpdataloaderfactory.h"
+
+#include "gimp-intl.h"
+
+
+/* Data files that have this string in their path are considered
+ * obsolete and are only kept around for backwards compatibility
+ */
+#define GIMP_OBSOLETE_DATA_DIR_NAME "gimp-obsolete-files"
+
+
+typedef struct _GimpDataLoader GimpDataLoader;
+
+struct _GimpDataLoader
+{
+  gchar            *name;
+  GimpDataLoadFunc  load_func;
+  gchar            *extension;
+  gboolean          writable;
+};
+
+
+struct _GimpDataLoaderFactoryPrivate
+{
+  GList          *loaders;
+  GimpDataLoader *fallback;
+};
+
+#define GET_PRIVATE(obj) (((GimpDataLoaderFactory *) (obj))->priv)
+
+
+static void   gimp_data_loader_factory_finalize       (GObject         *object);
+
+static void   gimp_data_loader_factory_data_init      (GimpDataFactory *factory,
+                                                       GimpContext     *context);
+static void   gimp_data_loader_factory_data_refresh   (GimpDataFactory *factory,
+                                                       GimpContext     *context);
+
+static GimpDataLoader *
+              gimp_data_loader_factory_get_loader     (GimpDataFactory *factory,
+                                                       GFile           *file);
+
+static void   gimp_data_loader_factory_load           (GimpDataFactory *factory,
+                                                       GimpContext     *context,
+                                                       GHashTable      *cache);
+static void   gimp_data_loader_factory_load_directory (GimpDataFactory *factory,
+                                                       GimpContext     *context,
+                                                       GHashTable      *cache,
+                                                       gboolean         dir_writable,
+                                                       GFile           *directory,
+                                                       GFile           *top_directory);
+static void   gimp_data_loader_factory_load_data      (GimpDataFactory *factory,
+                                                       GimpContext     *context,
+                                                       GHashTable      *cache,
+                                                       gboolean         dir_writable,
+                                                       GFile           *file,
+                                                       GFileInfo       *info,
+                                                       GFile           *top_directory);
+
+static GimpDataLoader * gimp_data_loader_new          (const gchar     *name,
+                                                       GimpDataLoadFunc load_func,
+                                                       const gchar     *extension,
+                                                       gboolean         writable);
+static void            gimp_data_loader_free          (GimpDataLoader  *loader);
+
+
+G_DEFINE_TYPE_WITH_PRIVATE (GimpDataLoaderFactory, gimp_data_loader_factory,
+                            GIMP_TYPE_DATA_FACTORY)
+
+#define parent_class gimp_data_loader_factory_parent_class
+
+
+static void
+gimp_data_loader_factory_class_init (GimpDataLoaderFactoryClass *klass)
+{
+  GObjectClass         *object_class  = G_OBJECT_CLASS (klass);
+  GimpDataFactoryClass *factory_class = GIMP_DATA_FACTORY_CLASS (klass);
+
+  object_class->finalize      = gimp_data_loader_factory_finalize;
+
+  factory_class->data_init    = gimp_data_loader_factory_data_init;
+  factory_class->data_refresh = gimp_data_loader_factory_data_refresh;
+}
+
+static void
+gimp_data_loader_factory_init (GimpDataLoaderFactory *factory)
+{
+  factory->priv = gimp_data_loader_factory_get_instance_private (factory);
+}
+
+static void
+gimp_data_loader_factory_finalize (GObject *object)
+{
+  GimpDataLoaderFactoryPrivate *priv = GET_PRIVATE (object);
+
+  g_list_free_full (priv->loaders, (GDestroyNotify) gimp_data_loader_free);
+  priv->loaders = NULL;
+
+  g_clear_pointer (&priv->fallback, gimp_data_loader_free);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gimp_data_loader_factory_data_init (GimpDataFactory *factory,
+                                    GimpContext     *context)
+{
+  gimp_data_loader_factory_load (factory, context, NULL);
+}
+
+static void
+gimp_data_loader_factory_refresh_cache_add (GimpDataFactory *factory,
+                                            GimpData        *data,
+                                            gpointer         user_data)
+{
+  GFile *file = gimp_data_get_file (data);
+
+  if (file)
+    {
+      GimpContainer *container = gimp_data_factory_get_container (factory);
+      GHashTable    *cache     = user_data;
+      GList         *list;
+
+      g_object_ref (data);
+
+      gimp_container_remove (container, GIMP_OBJECT (data));
+
+      list = g_hash_table_lookup (cache, file);
+      list = g_list_prepend (list, data);
+
+      g_hash_table_insert (cache, file, list);
+    }
+}
+
+static gboolean
+gimp_data_loader_factory_refresh_cache_remove (gpointer key,
+                                               gpointer value,
+                                               gpointer user_data)
+{
+  GList *list;
+
+  for (list = value; list; list = list->next)
+    g_object_unref (list->data);
+
+  g_list_free (value);
+
+  return TRUE;
+}
+
+static void
+gimp_data_loader_factory_data_refresh (GimpDataFactory *factory,
+                                       GimpContext     *context)
+{
+  GimpContainer *container = gimp_data_factory_get_container (factory);
+  GHashTable    *cache;
+
+  gimp_container_freeze (container);
+
+  /*  First, save all dirty data objects  */
+  gimp_data_factory_data_save (factory);
+
+  cache = g_hash_table_new (g_file_hash, (GEqualFunc) g_file_equal);
+
+  gimp_data_factory_data_foreach (factory, TRUE,
+                                  gimp_data_loader_factory_refresh_cache_add,
+                                  cache);
+
+  /*  Now the cache contains a GFile => list-of-objects mapping of
+   *  the old objects. So we should now traverse the directory and for
+   *  each file load it only if its mtime is newer.
+   *
+   *  Once a file was added, it is removed from the cache, so the only
+   *  objects remaining there will be those that are not present on
+   *  the disk (that have to be destroyed)
+   */
+  gimp_data_loader_factory_load (factory, context, cache);
+
+  /*  Now all the data is loaded. Free what remains in the cache  */
+  g_hash_table_foreach_remove (cache,
+                               gimp_data_loader_factory_refresh_cache_remove,
+                               NULL);
+
+  g_hash_table_destroy (cache);
+
+  gimp_container_thaw (container);
+}
+
+
+/*  public functions  */
+
+GimpDataFactory *
+gimp_data_loader_factory_new (Gimp                    *gimp,
+                              GType                    data_type,
+                              const gchar             *path_property_name,
+                              const gchar             *writable_property_name,
+                              GimpDataNewFunc          new_func,
+                              GimpDataGetStandardFunc  get_standard_func)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+  g_return_val_if_fail (g_type_is_a (data_type, GIMP_TYPE_DATA), NULL);
+  g_return_val_if_fail (path_property_name != NULL, NULL);
+  g_return_val_if_fail (writable_property_name != NULL, NULL);
+
+  return g_object_new (GIMP_TYPE_DATA_LOADER_FACTORY,
+                       "gimp",                   gimp,
+                       "data-type",              data_type,
+                       "path-property-name",     path_property_name,
+                       "writable-property-name", writable_property_name,
+                       "new-func",               new_func,
+                       "get-standard-func",      get_standard_func,
+                       NULL);
+}
+
+void
+gimp_data_loader_factory_add_loader (GimpDataFactory  *factory,
+                                     const gchar      *name,
+                                     GimpDataLoadFunc  load_func,
+                                     const gchar      *extension,
+                                     gboolean          writable)
+{
+  GimpDataLoaderFactoryPrivate *priv;
+  GimpDataLoader               *loader;
+
+  g_return_if_fail (GIMP_IS_DATA_LOADER_FACTORY (factory));
+  g_return_if_fail (name != NULL);
+  g_return_if_fail (load_func != NULL);
+  g_return_if_fail (extension != NULL);
+
+  priv = GET_PRIVATE (factory);
+
+  loader = gimp_data_loader_new (name, load_func, extension, writable);
+
+  priv->loaders = g_list_append (priv->loaders, loader);
+}
+
+void
+gimp_data_loader_factory_add_fallback (GimpDataFactory  *factory,
+                                       const gchar      *name,
+                                       GimpDataLoadFunc  load_func)
+{
+  GimpDataLoaderFactoryPrivate *priv;
+
+  g_return_if_fail (GIMP_IS_DATA_LOADER_FACTORY (factory));
+  g_return_if_fail (name != NULL);
+  g_return_if_fail (load_func != NULL);
+
+  priv = GET_PRIVATE (factory);
+
+  g_clear_pointer (&priv->fallback, gimp_data_loader_free);
+
+  priv->fallback = gimp_data_loader_new (name, load_func, NULL, FALSE);
+}
+
+
+/*  private functions  */
+
+static GimpDataLoader *
+gimp_data_loader_factory_get_loader (GimpDataFactory *factory,
+                                     GFile           *file)
+{
+  GimpDataLoaderFactoryPrivate *priv = GET_PRIVATE (factory);
+  GList                        *list;
+
+  for (list = priv->loaders; list; list = g_list_next (list))
+    {
+      GimpDataLoader *loader = list->data;
+
+      if (gimp_file_has_extension (file, loader->extension))
+        return loader;
+    }
+
+  return priv->fallback;
+}
+
+static void
+gimp_data_loader_factory_load (GimpDataFactory *factory,
+                               GimpContext     *context,
+                               GHashTable      *cache)
+{
+  GList *path;
+  GList *writable_path;
+  GList *list;
+
+  path          = gimp_data_factory_get_data_path          (factory);
+  writable_path = gimp_data_factory_get_data_path_writable (factory);
+
+  for (list = path; list; list = g_list_next (list))
+    {
+      gboolean dir_writable = FALSE;
+
+      if (g_list_find_custom (writable_path, list->data,
+                              (GCompareFunc) gimp_file_compare))
+        dir_writable = TRUE;
+
+      gimp_data_loader_factory_load_directory (factory, context, cache,
+                                               dir_writable,
+                                               list->data,
+                                               list->data);
+    }
+
+  g_list_free_full (path,          (GDestroyNotify) g_object_unref);
+  g_list_free_full (writable_path, (GDestroyNotify) g_object_unref);
+}
+
+static void
+gimp_data_loader_factory_load_directory (GimpDataFactory *factory,
+                                         GimpContext     *context,
+                                         GHashTable      *cache,
+                                         gboolean         dir_writable,
+                                         GFile           *directory,
+                                         GFile           *top_directory)
+{
+  GFileEnumerator *enumerator;
+
+  enumerator = g_file_enumerate_children (directory,
+                                          G_FILE_ATTRIBUTE_STANDARD_NAME ","
+                                          G_FILE_ATTRIBUTE_STANDARD_IS_HIDDEN ","
+                                          G_FILE_ATTRIBUTE_STANDARD_TYPE ","
+                                          G_FILE_ATTRIBUTE_TIME_MODIFIED,
+                                          G_FILE_QUERY_INFO_NONE,
+                                          NULL, NULL);
+
+  if (enumerator)
+    {
+      GFileInfo *info;
+
+      while ((info = g_file_enumerator_next_file (enumerator, NULL, NULL)))
+        {
+          GFileType  file_type;
+          GFile     *child;
+
+          if (g_file_info_get_is_hidden (info))
+            {
+              g_object_unref (info);
+              continue;
+            }
+
+          file_type = g_file_info_get_file_type (info);
+          child     = g_file_enumerator_get_child (enumerator, info);
+
+          if (file_type == G_FILE_TYPE_DIRECTORY)
+            {
+              gimp_data_loader_factory_load_directory (factory, context, cache,
+                                                       dir_writable,
+                                                       child,
+                                                       top_directory);
+            }
+          else if (file_type == G_FILE_TYPE_REGULAR)
+            {
+              gimp_data_loader_factory_load_data (factory, context, cache,
+                                                  dir_writable,
+                                                  child, info,
+                                                  top_directory);
+            }
+
+          g_object_unref (child);
+          g_object_unref (info);
+        }
+
+      g_object_unref (enumerator);
+    }
+}
+
+static void
+gimp_data_loader_factory_load_data (GimpDataFactory *factory,
+                                    GimpContext     *context,
+                                    GHashTable      *cache,
+                                    gboolean         dir_writable,
+                                    GFile           *file,
+                                    GFileInfo       *info,
+                                    GFile           *top_directory)
+{
+  GimpDataLoader *loader;
+  GimpContainer  *container;
+  GimpContainer  *container_obsolete;
+  GList          *data_list = NULL;
+  GInputStream   *input;
+  guint64         mtime;
+  GError         *error = NULL;
+
+  loader = gimp_data_loader_factory_get_loader (factory, file);
+
+  if (! loader)
+    return;
+
+  container          = gimp_data_factory_get_container          (factory);
+  container_obsolete = gimp_data_factory_get_container_obsolete (factory);
+
+  if (gimp_data_factory_get_gimp (factory)->be_verbose)
+    g_print ("  Loading %s\n", gimp_file_get_utf8_name (file));
+
+  mtime = g_file_info_get_attribute_uint64 (info,
+                                            G_FILE_ATTRIBUTE_TIME_MODIFIED);
+
+  if (cache)
+    {
+      GList *cached_data = g_hash_table_lookup (cache, file);
+
+      if (cached_data &&
+          gimp_data_get_mtime (cached_data->data) != 0 &&
+          gimp_data_get_mtime (cached_data->data) == mtime)
+        {
+          GList *list;
+
+          for (list = cached_data; list; list = g_list_next (list))
+            gimp_container_add (container, list->data);
+
+          return;
+        }
+    }
+
+  input = G_INPUT_STREAM (g_file_read (file, NULL, &error));
+
+  if (input)
+    {
+      GInputStream *buffered = g_buffered_input_stream_new (input);
+
+      data_list = loader->load_func (context, file, buffered, &error);
+
+      if (error)
+        {
+          g_prefix_error (&error,
+                          _("Error loading '%s': "),
+                          gimp_file_get_utf8_name (file));
+        }
+      else if (! data_list)
+        {
+          g_set_error (&error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                       _("Error loading '%s'"),
+                       gimp_file_get_utf8_name (file));
+        }
+
+      g_object_unref (buffered);
+      g_object_unref (input);
+    }
+  else
+    {
+      g_prefix_error (&error,
+                      _("Could not open '%s' for reading: "),
+                      gimp_file_get_utf8_name (file));
+    }
+
+  if (G_LIKELY (data_list))
+    {
+      GList    *list;
+      gchar    *uri;
+      gboolean  obsolete;
+      gboolean  writable  = FALSE;
+      gboolean  deletable = FALSE;
+
+      uri = g_file_get_uri (file);
+
+      obsolete = (strstr (uri, GIMP_OBSOLETE_DATA_DIR_NAME) != 0);
+
+      g_free (uri);
+
+      /* obsolete files are immutable, don't check their writability */
+      if (! obsolete)
+        {
+          deletable = (g_list_length (data_list) == 1 && dir_writable);
+          writable  = (deletable && loader->writable);
+        }
+
+      for (list = data_list; list; list = g_list_next (list))
+        {
+          GimpData *data = list->data;
+
+          gimp_data_set_file (data, file, writable, deletable);
+          gimp_data_set_mtime (data, mtime);
+          gimp_data_clean (data);
+
+          if (obsolete)
+            {
+              gimp_container_add (container_obsolete,
+                                  GIMP_OBJECT (data));
+            }
+          else
+            {
+              gimp_data_set_folder_tags (data, top_directory);
+
+              gimp_container_add (container,
+                                  GIMP_OBJECT (data));
+            }
+
+          g_object_unref (data);
+        }
+
+      g_list_free (data_list);
+    }
+
+  /*  not else { ... } because loader->load_func() can return a list
+   *  of data objects *and* an error message if loading failed after
+   *  something was already loaded
+   */
+  if (G_UNLIKELY (error))
+    {
+      gimp_message (gimp_data_factory_get_gimp (factory), NULL,
+                    GIMP_MESSAGE_ERROR,
+                    _("Failed to load data:\n\n%s"), error->message);
+      g_clear_error (&error);
+    }
+}
+
+static GimpDataLoader *
+gimp_data_loader_new (const gchar      *name,
+                      GimpDataLoadFunc  load_func,
+                      const gchar      *extension,
+                      gboolean          writable)
+{
+  GimpDataLoader *loader = g_slice_new (GimpDataLoader);
+
+  loader->name      = g_strdup (name);
+  loader->load_func = load_func;
+  loader->extension = g_strdup (extension);
+  loader->writable  = writable ? TRUE : FALSE;
+
+  return loader;
+}
+
+static void
+gimp_data_loader_free (GimpDataLoader *loader)
+{
+  g_free (loader->name);
+  g_free (loader->extension);
+
+  g_slice_free (GimpDataLoader, loader);
+}
diff --git a/app/core/gimpdataloaderfactory.h b/app/core/gimpdataloaderfactory.h
new file mode 100644
index 0000000..cf0d742
--- /dev/null
+++ b/app/core/gimpdataloaderfactory.h
@@ -0,0 +1,77 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpdataloaderfactory.h
+ * Copyright (C) 2001-2018 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_DATA_LOADER_FACTORY_H__
+#define __GIMP_DATA_LOADER_FACTORY_H__
+
+
+#include "gimpdatafactory.h"
+
+
+typedef GList * (* GimpDataLoadFunc) (GimpContext   *context,
+                                      GFile         *file,
+                                      GInputStream  *input,
+                                      GError       **error);
+
+
+#define GIMP_TYPE_DATA_LOADER_FACTORY            (gimp_data_loader_factory_get_type ())
+#define GIMP_DATA_LOADER_FACTORY(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_DATA_LOADER_FACTORY, GimpDataLoaderFactory))
+#define GIMP_DATA_LOADER_FACTORY_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_DATA_LOADER_FACTORY, GimpDataLoaderFactoryClass))
+#define GIMP_IS_DATA_LOADER_FACTORY(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_DATA_LOADER_FACTORY))
+#define GIMP_IS_DATA_LOADER_FACTORY_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_DATA_LOADER_FACTORY))
+#define GIMP_DATA_LOADER_FACTORY_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_DATA_LOADER_FACTORY, GimpDataLoaderFactoryClass))
+
+
+typedef struct _GimpDataLoaderFactoryPrivate GimpDataLoaderFactoryPrivate;
+typedef struct _GimpDataLoaderFactoryClass   GimpDataLoaderFactoryClass;
+
+struct _GimpDataLoaderFactory
+{
+  GimpDataFactory               parent_instance;
+
+  GimpDataLoaderFactoryPrivate *priv;
+};
+
+struct _GimpDataLoaderFactoryClass
+{
+  GimpDataFactoryClass  parent_class;
+};
+
+
+GType             gimp_data_loader_factory_get_type     (void) G_GNUC_CONST;
+
+GimpDataFactory * gimp_data_loader_factory_new          (Gimp                   *gimp,
+                                                         GType                   data_type,
+                                                         const gchar            *path_property_name,
+                                                         const gchar            *writable_property_name,
+                                                         GimpDataNewFunc         new_func,
+                                                         GimpDataGetStandardFunc  get_standard_func);
+
+void              gimp_data_loader_factory_add_loader   (GimpDataFactory         *factory,
+                                                         const gchar             *name,
+                                                         GimpDataLoadFunc         load_func,
+                                                         const gchar             *extension,
+                                                         gboolean                 writable);
+void              gimp_data_loader_factory_add_fallback (GimpDataFactory         *factory,
+                                                         const gchar             *name,
+                                                         GimpDataLoadFunc         load_func);
+
+
+#endif  /*  __GIMP_DATA_LOADER_FACTORY_H__  */
diff --git a/app/core/gimpdocumentlist.c b/app/core/gimpdocumentlist.c
new file mode 100644
index 0000000..fe10f6f
--- /dev/null
+++ b/app/core/gimpdocumentlist.c
@@ -0,0 +1,106 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1997 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpconfig/gimpconfig.h"
+
+#include "core-types.h"
+
+#include "config/gimpcoreconfig.h"
+
+#include "gimp.h"
+#include "gimpdocumentlist.h"
+#include "gimpimagefile.h"
+
+
+G_DEFINE_TYPE (GimpDocumentList, gimp_document_list, GIMP_TYPE_LIST)
+
+
+static void
+gimp_document_list_class_init (GimpDocumentListClass *klass)
+{
+}
+
+static void
+gimp_document_list_init (GimpDocumentList *list)
+{
+}
+
+GimpContainer *
+gimp_document_list_new (Gimp *gimp)
+{
+  GimpDocumentList *document_list;
+
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  document_list = g_object_new (GIMP_TYPE_DOCUMENT_LIST,
+                                "name",          "document-list",
+                                "children-type", GIMP_TYPE_IMAGEFILE,
+                                "policy",        GIMP_CONTAINER_POLICY_STRONG,
+                                NULL);
+
+  document_list->gimp = gimp;
+
+  return GIMP_CONTAINER (document_list);
+}
+
+GimpImagefile *
+gimp_document_list_add_file (GimpDocumentList *document_list,
+                             GFile            *file,
+                             const gchar      *mime_type)
+{
+  Gimp          *gimp;
+  GimpImagefile *imagefile;
+  GimpContainer *container;
+  gchar         *uri;
+
+  g_return_val_if_fail (GIMP_IS_DOCUMENT_LIST (document_list), NULL);
+  g_return_val_if_fail (G_IS_FILE (file), NULL);
+
+  container = GIMP_CONTAINER (document_list);
+
+  gimp = document_list->gimp;
+
+  uri = g_file_get_uri (file);
+
+  imagefile = (GimpImagefile *) gimp_container_get_child_by_name (container,
+                                                                  uri);
+
+  g_free (uri);
+
+  if (imagefile)
+    {
+      gimp_container_reorder (container, GIMP_OBJECT (imagefile), 0);
+    }
+  else
+    {
+      imagefile = gimp_imagefile_new (gimp, file);
+      gimp_container_add (container, GIMP_OBJECT (imagefile));
+      g_object_unref (imagefile);
+    }
+
+  gimp_imagefile_set_mime_type (imagefile, mime_type);
+
+  if (gimp->config->save_document_history)
+    gimp_recent_list_add_file (gimp, file, mime_type);
+
+  return imagefile;
+}
diff --git a/app/core/gimpdocumentlist.h b/app/core/gimpdocumentlist.h
new file mode 100644
index 0000000..68bca80
--- /dev/null
+++ b/app/core/gimpdocumentlist.h
@@ -0,0 +1,54 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1997 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_DOCUMENT_LIST_H__
+#define __GIMP_DOCUMENT_LIST_H__
+
+#include "core/gimplist.h"
+
+
+#define GIMP_TYPE_DOCUMENT_LIST           (gimp_document_list_get_type ())
+#define GIMP_DOCUMENT_LIST(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_DOCUMENT_LIST, GimpDocumentList))
+#define GIMP_DOCUMENT_LIST_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_DOCUMENT_LIST, GimpDocumentListClass))
+#define GIMP_IS_DOCUMENT_LIST(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_DOCUMENT_LIST))
+#define GIMP_IS_DOCUMENT_LIST_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_DOCUMENT_LIST))
+
+
+typedef struct _GimpDocumentListClass GimpDocumentListClass;
+
+struct _GimpDocumentList
+{
+  GimpList  parent_instance;
+
+  Gimp     *gimp;
+};
+
+struct _GimpDocumentListClass
+{
+  GimpListClass  parent_class;
+};
+
+
+GType           gimp_document_list_get_type (void) G_GNUC_CONST;
+GimpContainer * gimp_document_list_new      (Gimp             *gimp);
+
+GimpImagefile * gimp_document_list_add_file (GimpDocumentList *document_list,
+                                             GFile            *file,
+                                             const gchar      *mime_type);
+
+
+#endif  /*  __GIMP_DOCUMENT_LIST_H__  */
diff --git a/app/core/gimpdrawable-bucket-fill.c b/app/core/gimpdrawable-bucket-fill.c
new file mode 100644
index 0000000..1cef758
--- /dev/null
+++ b/app/core/gimpdrawable-bucket-fill.c
@@ -0,0 +1,499 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <cairo.h>
+#define GEGL_ITERATOR2_API
+#include <gegl.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpcolor/gimpcolor.h"
+
+#include "core-types.h"
+
+#include "gegl/gimp-gegl-apply-operation.h"
+#include "gegl/gimp-gegl-mask.h"
+#include "gegl/gimp-gegl-mask-combine.h"
+#include "gegl/gimp-gegl-utils.h"
+
+#include "operations/layer-modes/gimp-layer-modes.h"
+
+#include "gimp.h"
+#include "gimpchannel.h"
+#include "gimpdrawable.h"
+#include "gimpdrawable-bucket-fill.h"
+#include "gimpfilloptions.h"
+#include "gimpimage.h"
+#include "gimppickable.h"
+#include "gimppickable-contiguous-region.h"
+
+#include "gimp-intl.h"
+
+
+/*  public functions  */
+
+void
+gimp_drawable_bucket_fill (GimpDrawable         *drawable,
+                           GimpFillOptions      *options,
+                           gboolean              fill_transparent,
+                           GimpSelectCriterion   fill_criterion,
+                           gdouble               threshold,
+                           gboolean              sample_merged,
+                           gboolean              diagonal_neighbors,
+                           gdouble               seed_x,
+                           gdouble               seed_y)
+{
+  GimpImage  *image;
+  GeglBuffer *buffer;
+  gdouble     mask_x;
+  gdouble     mask_y;
+  gint        width, height;
+
+  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
+  g_return_if_fail (gimp_item_is_attached (GIMP_ITEM (drawable)));
+  g_return_if_fail (GIMP_IS_FILL_OPTIONS (options));
+
+  image = gimp_item_get_image (GIMP_ITEM (drawable));
+
+  gimp_set_busy (image->gimp);
+
+  buffer = gimp_drawable_get_bucket_fill_buffer (drawable, options,
+                                                 fill_transparent, fill_criterion,
+                                                 threshold, FALSE, sample_merged,
+                                                 diagonal_neighbors,
+                                                 seed_x, seed_y, NULL,
+                                                 &mask_x, &mask_y, &width, &height);
+
+  if (buffer)
+    {
+      /*  Apply it to the image  */
+      gimp_drawable_apply_buffer (drawable, buffer,
+                                  GEGL_RECTANGLE (0, 0, width, height),
+                                  TRUE, C_("undo-type", "Bucket Fill"),
+                                  gimp_context_get_opacity (GIMP_CONTEXT (options)),
+                                  gimp_context_get_paint_mode (GIMP_CONTEXT (options)),
+                                  GIMP_LAYER_COLOR_SPACE_AUTO,
+                                  GIMP_LAYER_COLOR_SPACE_AUTO,
+                                  gimp_layer_mode_get_paint_composite_mode
+                                  (gimp_context_get_paint_mode (GIMP_CONTEXT (options))),
+                                  NULL, (gint) mask_x, mask_y);
+      g_object_unref (buffer);
+
+      gimp_drawable_update (drawable, mask_x, mask_y, width, height);
+    }
+
+  gimp_unset_busy (image->gimp);
+}
+
+/**
+ * gimp_drawable_get_bucket_fill_buffer:
+ * @drawable: the #GimpDrawable to edit.
+ * @options:
+ * @fill_transparent:
+ * @fill_criterion:
+ * @threshold:
+ * @show_all:
+ * @sample_merged:
+ * @diagonal_neighbors:
+ * @seed_x: X coordinate to start the fill.
+ * @seed_y: Y coordinate to start the fill.
+ * @mask_buffer: mask of the fill in-progress when in an interactive
+ *               filling process. Set to NULL if you need a one-time
+ *               fill.
+ * @mask_x: returned x bound of @mask_buffer.
+ * @mask_y: returned x bound of @mask_buffer.
+ * @mask_width: returned width bound of @mask_buffer.
+ * @mask_height: returned height bound of @mask_buffer.
+ *
+ * Creates the fill buffer for a bucket fill operation on @drawable,
+ * without actually applying it (if you want to apply it directly as a
+ * one-time operation, use gimp_drawable_bucket_fill() instead). If
+ * @mask_buffer is not NULL, the intermediate fill mask will also be
+ * returned. This fill mask can later be reused in successive calls to
+ * gimp_drawable_get_bucket_fill_buffer() for interactive filling.
+ *
+ * Returns: a fill buffer which can be directly applied to @drawable, or
+ *          used in a drawable filter as preview.
+ */
+GeglBuffer *
+gimp_drawable_get_bucket_fill_buffer (GimpDrawable         *drawable,
+                                      GimpFillOptions      *options,
+                                      gboolean              fill_transparent,
+                                      GimpSelectCriterion   fill_criterion,
+                                      gdouble               threshold,
+                                      gboolean              show_all,
+                                      gboolean              sample_merged,
+                                      gboolean              diagonal_neighbors,
+                                      gdouble               seed_x,
+                                      gdouble               seed_y,
+                                      GeglBuffer          **mask_buffer,
+                                      gdouble              *mask_x,
+                                      gdouble              *mask_y,
+                                      gint                 *mask_width,
+                                      gint                 *mask_height)
+{
+  GimpImage    *image;
+  GimpPickable *pickable;
+  GeglBuffer   *buffer;
+  GeglBuffer   *new_mask;
+  gboolean      antialias;
+  gint          x, y, width, height;
+  gint          mask_offset_x = 0;
+  gint          mask_offset_y = 0;
+  gint          sel_x, sel_y, sel_width, sel_height;
+
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (drawable)), NULL);
+  g_return_val_if_fail (GIMP_IS_FILL_OPTIONS (options), NULL);
+
+  image = gimp_item_get_image (GIMP_ITEM (drawable));
+
+  if (! gimp_item_mask_intersect (GIMP_ITEM (drawable),
+                                  &sel_x, &sel_y, &sel_width, &sel_height))
+    return NULL;
+
+  if (mask_buffer && *mask_buffer && threshold == 0.0)
+    {
+      gfloat pixel;
+
+      gegl_buffer_sample (*mask_buffer, seed_x, seed_y, NULL, &pixel,
+                          babl_format ("Y float"),
+                          GEGL_SAMPLER_NEAREST, GEGL_ABYSS_NONE);
+
+      if (pixel != 0.0)
+        /* Already selected. This seed won't change the selection. */
+        return NULL;
+    }
+
+  gimp_set_busy (image->gimp);
+
+  if (sample_merged)
+    {
+      if (! show_all)
+        pickable = GIMP_PICKABLE (image);
+      else
+        pickable = GIMP_PICKABLE (gimp_image_get_projection (image));
+    }
+  else
+    {
+      pickable = GIMP_PICKABLE (drawable);
+    }
+
+  antialias = gimp_fill_options_get_antialias (options);
+
+  /*  Do a seed bucket fill...To do this, calculate a new
+   *  contiguous region.
+   */
+  new_mask = gimp_pickable_contiguous_region_by_seed (pickable,
+                                                      antialias,
+                                                      threshold,
+                                                      fill_transparent,
+                                                      fill_criterion,
+                                                      diagonal_neighbors,
+                                                      (gint) seed_x,
+                                                      (gint) seed_y);
+  if (mask_buffer && *mask_buffer)
+    {
+      gimp_gegl_mask_combine_buffer (new_mask, *mask_buffer,
+                                     GIMP_CHANNEL_OP_ADD, 0, 0);
+      g_object_unref (*mask_buffer);
+    }
+
+  if (mask_buffer)
+    *mask_buffer = new_mask;
+
+  gimp_gegl_mask_bounds (new_mask, &x, &y, &width, &height);
+  width  -= x;
+  height -= y;
+
+  /*  If there is a selection, intersect the region bounds
+   *  with the selection bounds, to avoid processing areas
+   *  that are going to be masked out anyway.  The actual
+   *  intersection of the fill region with the mask data
+   *  happens when combining the fill buffer, in
+   *  gimp_drawable_apply_buffer().
+   */
+  if (! gimp_channel_is_empty (gimp_image_get_mask (image)))
+    {
+      gint off_x = 0;
+      gint off_y = 0;
+
+      if (sample_merged)
+        gimp_item_get_offset (GIMP_ITEM (drawable), &off_x, &off_y);
+
+      if (! gimp_rectangle_intersect (x, y, width, height,
+
+                                      sel_x + off_x, sel_y + off_y,
+                                      sel_width,     sel_height,
+
+                                      &x, &y, &width, &height))
+        {
+          /*  The fill region and the selection are disjoint; bail.  */
+
+          if (! mask_buffer)
+            g_object_unref (new_mask);
+
+          gimp_unset_busy (image->gimp);
+
+          return NULL;
+        }
+    }
+
+  /*  make sure we handle the mask correctly if it was sample-merged  */
+  if (sample_merged)
+    {
+      GimpItem *item = GIMP_ITEM (drawable);
+      gint      off_x, off_y;
+
+      /*  Limit the channel bounds to the drawable's extents  */
+      gimp_item_get_offset (item, &off_x, &off_y);
+
+      gimp_rectangle_intersect (x, y, width, height,
+
+                                off_x, off_y,
+                                gimp_item_get_width (item),
+                                gimp_item_get_height (item),
+
+                                &x, &y, &width, &height);
+
+      mask_offset_x = x;
+      mask_offset_y = y;
+
+      /*  translate mask bounds to drawable coords  */
+      x -= off_x;
+      y -= off_y;
+    }
+  else
+    {
+      mask_offset_x = x;
+      mask_offset_y = y;
+    }
+
+  buffer = gimp_fill_options_create_buffer (options, drawable,
+                                            GEGL_RECTANGLE (0, 0,
+                                                            width, height),
+                                            -x, -y);
+
+  gimp_gegl_apply_opacity (buffer, NULL, NULL, buffer, new_mask,
+                           -mask_offset_x, -mask_offset_y, 1.0);
+
+  if (mask_x)
+    *mask_x = x;
+  if (mask_y)
+    *mask_y = y;
+  if (mask_width)
+    *mask_width = width;
+  if (mask_height)
+    *mask_height = height;
+
+  if (! mask_buffer)
+    g_object_unref (new_mask);
+
+  gimp_unset_busy (image->gimp);
+
+  return buffer;
+}
+
+/**
+ * gimp_drawable_get_line_art_fill_buffer:
+ * @drawable: the #GimpDrawable to edit.
+ * @line_art: the #GimpLineArt computed as fill source.
+ * @options: the #GimpFillOptions.
+ * @sample_merged:
+ * @seed_x: X coordinate to start the fill.
+ * @seed_y: Y coordinate to start the fill.
+ * @mask_buffer: mask of the fill in-progress when in an interactive
+ *               filling process. Set to NULL if you need a one-time
+ *               fill.
+ * @mask_x: returned x bound of @mask_buffer.
+ * @mask_y: returned x bound of @mask_buffer.
+ * @mask_width: returned width bound of @mask_buffer.
+ * @mask_height: returned height bound of @mask_buffer.
+ *
+ * Creates the fill buffer for a bucket fill operation on @drawable
+ * based on @line_art and @options, without actually applying it.
+ * If @mask_buffer is not NULL, the intermediate fill mask will also be
+ * returned. This fill mask can later be reused in successive calls to
+ * gimp_drawable_get_bucket_fill_buffer() for interactive filling.
+ *
+ * Returns: a fill buffer which can be directly applied to @drawable, or
+ *          used in a drawable filter as preview.
+ */
+GeglBuffer *
+gimp_drawable_get_line_art_fill_buffer (GimpDrawable     *drawable,
+                                        GimpLineArt      *line_art,
+                                        GimpFillOptions  *options,
+                                        gboolean          sample_merged,
+                                        gdouble           seed_x,
+                                        gdouble           seed_y,
+                                        GeglBuffer      **mask_buffer,
+                                        gdouble          *mask_x,
+                                        gdouble          *mask_y,
+                                        gint             *mask_width,
+                                        gint             *mask_height)
+{
+  GimpImage  *image;
+  GeglBuffer *buffer;
+  GeglBuffer *new_mask;
+  gint        x, y, width, height;
+  gint        mask_offset_x = 0;
+  gint        mask_offset_y = 0;
+  gint        sel_x, sel_y, sel_width, sel_height;
+  gdouble     feather_radius;
+
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (drawable)), NULL);
+  g_return_val_if_fail (GIMP_IS_FILL_OPTIONS (options), NULL);
+
+  image = gimp_item_get_image (GIMP_ITEM (drawable));
+
+  if (! gimp_item_mask_intersect (GIMP_ITEM (drawable),
+                                  &sel_x, &sel_y, &sel_width, &sel_height))
+    return NULL;
+
+  if (mask_buffer && *mask_buffer)
+    {
+      gfloat pixel;
+
+      gegl_buffer_sample (*mask_buffer, seed_x, seed_y, NULL, &pixel,
+                          babl_format ("Y float"),
+                          GEGL_SAMPLER_NEAREST, GEGL_ABYSS_NONE);
+
+      if (pixel != 0.0)
+        /* Already selected. This seed won't change the selection. */
+        return NULL;
+    }
+
+  gimp_set_busy (image->gimp);
+
+  /*  Do a seed bucket fill...To do this, calculate a new
+   *  contiguous region.
+   */
+  new_mask = gimp_pickable_contiguous_region_by_line_art (NULL, line_art,
+                                                          (gint) seed_x,
+                                                          (gint) seed_y);
+  if (mask_buffer && *mask_buffer)
+    {
+      gimp_gegl_mask_combine_buffer (new_mask, *mask_buffer,
+                                     GIMP_CHANNEL_OP_ADD, 0, 0);
+      g_object_unref (*mask_buffer);
+    }
+  if (mask_buffer)
+    *mask_buffer = new_mask;
+
+  gimp_gegl_mask_bounds (new_mask, &x, &y, &width, &height);
+  width  -= x;
+  height -= y;
+
+  /*  If there is a selection, intersect the region bounds
+   *  with the selection bounds, to avoid processing areas
+   *  that are going to be masked out anyway.  The actual
+   *  intersection of the fill region with the mask data
+   *  happens when combining the fill buffer, in
+   *  gimp_drawable_apply_buffer().
+   */
+  if (! gimp_channel_is_empty (gimp_image_get_mask (image)))
+    {
+      gint off_x = 0;
+      gint off_y = 0;
+
+      if (sample_merged)
+        gimp_item_get_offset (GIMP_ITEM (drawable), &off_x, &off_y);
+
+      if (! gimp_rectangle_intersect (x, y, width, height,
+
+                                      sel_x + off_x, sel_y + off_y,
+                                      sel_width,     sel_height,
+
+                                      &x, &y, &width, &height))
+        {
+          if (! mask_buffer)
+            g_object_unref (new_mask);
+          /*  The fill region and the selection are disjoint; bail.  */
+          gimp_unset_busy (image->gimp);
+
+          return NULL;
+        }
+    }
+
+  /*  make sure we handle the mask correctly if it was sample-merged  */
+  if (sample_merged)
+    {
+      GimpItem *item = GIMP_ITEM (drawable);
+      gint      off_x, off_y;
+
+      /*  Limit the channel bounds to the drawable's extents  */
+      gimp_item_get_offset (item, &off_x, &off_y);
+
+      gimp_rectangle_intersect (x, y, width, height,
+
+                                off_x, off_y,
+                                gimp_item_get_width (item),
+                                gimp_item_get_height (item),
+
+                                &x, &y, &width, &height);
+
+      mask_offset_x = x;
+      mask_offset_y = y;
+
+      /*  translate mask bounds to drawable coords  */
+      x -= off_x;
+      y -= off_y;
+    }
+  else
+    {
+      mask_offset_x = x;
+      mask_offset_y = y;
+    }
+
+  buffer = gimp_fill_options_create_buffer (options, drawable,
+                                            GEGL_RECTANGLE (0, 0,
+                                                            width, height),
+                                            -x, -y);
+
+  gimp_gegl_apply_opacity (buffer, NULL, NULL, buffer, new_mask,
+                           -mask_offset_x, -mask_offset_y, 1.0);
+
+  if (gimp_fill_options_get_feather (options, &feather_radius))
+    {
+      /* Feathering for the line art algorithm is not applied during
+       * mask creation because we just want to apply it on the borders
+       * of the mask at the end (since the mask can evolve, we don't
+       * want to actually touch it, but only the intermediate results).
+       */
+      gimp_gegl_apply_feather (buffer, NULL, NULL, buffer, NULL,
+                               feather_radius, feather_radius, TRUE);
+    }
+
+  if (mask_x)
+    *mask_x = x;
+  if (mask_y)
+    *mask_y = y;
+  if (mask_width)
+    *mask_width = width;
+  if (mask_height)
+    *mask_height = height;
+
+  if (! mask_buffer)
+    g_object_unref (new_mask);
+
+  gimp_unset_busy (image->gimp);
+
+  return buffer;
+}
diff --git a/app/core/gimpdrawable-bucket-fill.h b/app/core/gimpdrawable-bucket-fill.h
new file mode 100644
index 0000000..148de97
--- /dev/null
+++ b/app/core/gimpdrawable-bucket-fill.h
@@ -0,0 +1,59 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef  __GIMP_DRAWABLE_BUCKET_FILL_H__
+#define  __GIMP_DRAWABLE_BUCKET_FILL_H__
+
+
+void         gimp_drawable_bucket_fill              (GimpDrawable         *drawable,
+                                                     GimpFillOptions      *options,
+                                                     gboolean              fill_transparent,
+                                                     GimpSelectCriterion   fill_criterion,
+                                                     gdouble               threshold,
+                                                     gboolean              sample_merged,
+                                                     gboolean              diagonal_neighbors,
+                                                     gdouble               x,
+                                                     gdouble               y);
+GeglBuffer * gimp_drawable_get_bucket_fill_buffer   (GimpDrawable         *drawable,
+                                                     GimpFillOptions      *options,
+                                                     gboolean              fill_transparent,
+                                                     GimpSelectCriterion   fill_criterion,
+                                                     gdouble               threshold,
+                                                     gboolean              show_all,
+                                                     gboolean              sample_merged,
+                                                     gboolean              diagonal_neighbors,
+                                                     gdouble               seed_x,
+                                                     gdouble               seed_y,
+                                                     GeglBuffer          **mask_buffer,
+                                                     gdouble              *mask_x,
+                                                     gdouble              *mask_y,
+                                                     gint                 *mask_width,
+                                                     gint                 *mask_height);
+
+GeglBuffer * gimp_drawable_get_line_art_fill_buffer (GimpDrawable         *drawable,
+                                                     GimpLineArt          *line_art,
+                                                     GimpFillOptions      *options,
+                                                     gboolean              sample_merged,
+                                                     gdouble               seed_x,
+                                                     gdouble               seed_y,
+                                                     GeglBuffer          **mask_buffer,
+                                                     gdouble              *mask_x,
+                                                     gdouble              *mask_y,
+                                                     gint                 *mask_width,
+                                                     gint                 *mask_height);
+
+#endif  /*  __GIMP_DRAWABLE_BUCKET_FILL_H__  */
diff --git a/app/core/gimpdrawable-combine.c b/app/core/gimpdrawable-combine.c
new file mode 100644
index 0000000..e48d9dd
--- /dev/null
+++ b/app/core/gimpdrawable-combine.c
@@ -0,0 +1,144 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <cairo.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+
+#include "core-types.h"
+
+#include "gegl/gimpapplicator.h"
+
+#include "gimp.h"
+#include "gimpchannel.h"
+#include "gimpchunkiterator.h"
+#include "gimpdrawable-combine.h"
+#include "gimpimage.h"
+
+
+void
+gimp_drawable_real_apply_buffer (GimpDrawable           *drawable,
+                                 GeglBuffer             *buffer,
+                                 const GeglRectangle    *buffer_region,
+                                 gboolean                push_undo,
+                                 const gchar            *undo_desc,
+                                 gdouble                 opacity,
+                                 GimpLayerMode           mode,
+                                 GimpLayerColorSpace     blend_space,
+                                 GimpLayerColorSpace     composite_space,
+                                 GimpLayerCompositeMode  composite_mode,
+                                 GeglBuffer             *base_buffer,
+                                 gint                    base_x,
+                                 gint                    base_y)
+{
+  GimpItem          *item  = GIMP_ITEM (drawable);
+  GimpImage         *image = gimp_item_get_image (item);
+  GimpChannel       *mask  = gimp_image_get_mask (image);
+  GimpApplicator    *applicator;
+  GimpChunkIterator *iter;
+  gint               x, y, width, height;
+  gint               offset_x, offset_y;
+
+  /*  don't apply the mask to itself and don't apply an empty mask  */
+  if (GIMP_DRAWABLE (mask) == drawable || gimp_channel_is_empty (mask))
+    mask = NULL;
+
+  if (! base_buffer)
+    base_buffer = gimp_drawable_get_buffer (drawable);
+
+  /*  get the layer offsets  */
+  gimp_item_get_offset (item, &offset_x, &offset_y);
+
+  /*  make sure the image application coordinates are within drawable bounds  */
+  if (! gimp_rectangle_intersect (base_x, base_y,
+                                  buffer_region->width, buffer_region->height,
+                                  0, 0,
+                                  gimp_item_get_width  (item),
+                                  gimp_item_get_height (item),
+                                  &x, &y, &width, &height))
+    {
+      return;
+    }
+
+  if (mask)
+    {
+      GimpItem *mask_item = GIMP_ITEM (mask);
+
+      /*  make sure coordinates are in mask bounds ...
+       *  we need to add the layer offset to transform coords
+       *  into the mask coordinate system
+       */
+      if (! gimp_rectangle_intersect (x, y, width, height,
+                                      -offset_x, -offset_y,
+                                      gimp_item_get_width  (mask_item),
+                                      gimp_item_get_height (mask_item),
+                                      &x, &y, &width, &height))
+        {
+          return;
+        }
+    }
+
+  if (push_undo)
+    {
+      gimp_drawable_push_undo (drawable, undo_desc,
+                               NULL, x, y, width, height);
+    }
+
+  applicator = gimp_applicator_new (NULL);
+
+  if (mask)
+    {
+      GeglBuffer *mask_buffer;
+
+      mask_buffer = gimp_drawable_get_buffer (GIMP_DRAWABLE (mask));
+
+      gimp_applicator_set_mask_buffer (applicator, mask_buffer);
+      gimp_applicator_set_mask_offset (applicator, -offset_x, -offset_y);
+    }
+
+  gimp_applicator_set_src_buffer (applicator, base_buffer);
+  gimp_applicator_set_dest_buffer (applicator,
+                                   gimp_drawable_get_buffer (drawable));
+
+  gimp_applicator_set_apply_buffer (applicator, buffer);
+  gimp_applicator_set_apply_offset (applicator,
+                                    base_x - buffer_region->x,
+                                    base_y - buffer_region->y);
+
+  gimp_applicator_set_opacity (applicator, opacity);
+  gimp_applicator_set_mode (applicator, mode,
+                            blend_space, composite_space, composite_mode);
+  gimp_applicator_set_affect (applicator,
+                              gimp_drawable_get_active_mask (drawable));
+
+  iter = gimp_chunk_iterator_new (cairo_region_create_rectangle (
+    &(cairo_rectangle_int_t) {x, y, width, height}));
+
+  while (gimp_chunk_iterator_next (iter))
+    {
+      GeglRectangle rect;
+
+      while (gimp_chunk_iterator_get_rect (iter, &rect))
+        gimp_applicator_blit (applicator, &rect);
+    }
+
+  g_object_unref (applicator);
+}
diff --git a/app/core/gimpdrawable-combine.h b/app/core/gimpdrawable-combine.h
new file mode 100644
index 0000000..d21d558
--- /dev/null
+++ b/app/core/gimpdrawable-combine.h
@@ -0,0 +1,39 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_DRAWABLE_COMBINE_H__
+#define __GIMP_DRAWABLE_COMBINE_H__
+
+
+/*  virtual functions of GimpDrawable, don't call directly  */
+
+void   gimp_drawable_real_apply_buffer (GimpDrawable           *drawable,
+                                        GeglBuffer             *buffer,
+                                        const GeglRectangle    *buffer_region,
+                                        gboolean                push_undo,
+                                        const gchar            *undo_desc,
+                                        gdouble                 opacity,
+                                        GimpLayerMode           mode,
+                                        GimpLayerColorSpace     blend_space,
+                                        GimpLayerColorSpace     composite_space,
+                                        GimpLayerCompositeMode  composite_mode,
+                                        GeglBuffer             *base_buffer,
+                                        gint                    base_x,
+                                        gint                    base_y);
+
+
+#endif /* __GIMP_DRAWABLE_COMBINE_H__ */
diff --git a/app/core/gimpdrawable-edit.c b/app/core/gimpdrawable-edit.c
new file mode 100644
index 0000000..214b8fb
--- /dev/null
+++ b/app/core/gimpdrawable-edit.c
@@ -0,0 +1,231 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gegl.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "core-types.h"
+
+#include "operations/layer-modes/gimp-layer-modes.h"
+
+#include "gegl/gimp-gegl-loops.h"
+
+#include "gimpchannel.h"
+#include "gimpdrawable.h"
+#include "gimpdrawable-edit.h"
+#include "gimpdrawablefilter.h"
+#include "gimpcontext.h"
+#include "gimpfilloptions.h"
+#include "gimpimage.h"
+#include "gimppattern.h"
+#include "gimptempbuf.h"
+
+#include "gimp-intl.h"
+
+
+/*  local function prototypes  */
+
+static gboolean   gimp_drawable_edit_can_fill_direct (GimpDrawable    *drawable,
+                                                      GimpFillOptions *options);
+static void       gimp_drawable_edit_fill_direct     (GimpDrawable    *drawable,
+                                                      GimpFillOptions *options,
+                                                      const gchar     *undo_desc);
+
+
+/*  private functions  */
+
+static gboolean
+gimp_drawable_edit_can_fill_direct (GimpDrawable    *drawable,
+                                    GimpFillOptions *options)
+{
+  GimpImage                *image;
+  GimpContext              *context;
+  gdouble                   opacity;
+  GimpComponentMask         affect;
+  GimpLayerMode             mode;
+  GimpLayerCompositeMode    composite_mode;
+  GimpLayerCompositeRegion  composite_region;
+
+  image            = gimp_item_get_image (GIMP_ITEM (drawable));
+  context          = GIMP_CONTEXT (options);
+  opacity          = gimp_context_get_opacity (context);
+  affect           = gimp_drawable_get_active_mask (drawable);
+  mode             = gimp_context_get_paint_mode (context);
+  composite_mode   = gimp_layer_mode_get_paint_composite_mode (mode);
+  composite_region = gimp_layer_mode_get_included_region (mode, composite_mode);
+
+  if (gimp_channel_is_empty (gimp_image_get_mask (image)) &&
+      opacity == GIMP_OPACITY_OPAQUE                      &&
+      affect  == GIMP_COMPONENT_MASK_ALL                  &&
+      gimp_layer_mode_is_trivial (mode)                   &&
+      (! gimp_layer_mode_is_subtractive (mode)            ^
+       ! (composite_region & GIMP_LAYER_COMPOSITE_REGION_SOURCE)))
+    {
+      switch (gimp_fill_options_get_style (options))
+        {
+        case GIMP_FILL_STYLE_SOLID:
+          return TRUE;
+
+        case GIMP_FILL_STYLE_PATTERN:
+          {
+            GimpPattern *pattern;
+            GimpTempBuf *mask;
+            const Babl  *format;
+
+            pattern = gimp_context_get_pattern (context);
+            mask    = gimp_pattern_get_mask (pattern);
+            format  = gimp_temp_buf_get_format (mask);
+
+            return ! babl_format_has_alpha (format);
+          }
+        }
+    }
+
+  return FALSE;
+}
+
+static void
+gimp_drawable_edit_fill_direct (GimpDrawable    *drawable,
+                                GimpFillOptions *options,
+                                const gchar     *undo_desc)
+{
+  GeglBuffer    *buffer;
+  GimpContext   *context;
+  GimpLayerMode  mode;
+  gint           width;
+  gint           height;
+
+  buffer  = gimp_drawable_get_buffer (drawable);
+  context = GIMP_CONTEXT (options);
+  mode    = gimp_context_get_paint_mode (context);
+  width   = gimp_item_get_width  (GIMP_ITEM (drawable));
+  height  = gimp_item_get_height (GIMP_ITEM (drawable));
+
+  gimp_drawable_push_undo (drawable, undo_desc,
+                           NULL, 0, 0, width, height);
+
+  if (! gimp_layer_mode_is_subtractive (mode))
+    gimp_fill_options_fill_buffer (options, drawable, buffer, 0, 0);
+  else
+    gimp_gegl_clear (buffer, NULL);
+}
+
+
+/*  public functions  */
+
+void
+gimp_drawable_edit_clear (GimpDrawable *drawable,
+                          GimpContext  *context)
+{
+  GimpFillOptions *options;
+
+  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
+  g_return_if_fail (gimp_item_is_attached (GIMP_ITEM (drawable)));
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  options = gimp_fill_options_new (context->gimp, NULL, FALSE);
+
+  if (gimp_drawable_has_alpha (drawable))
+    gimp_fill_options_set_by_fill_type (options, context,
+                                        GIMP_FILL_TRANSPARENT, NULL);
+  else
+    gimp_fill_options_set_by_fill_type (options, context,
+                                        GIMP_FILL_BACKGROUND, NULL);
+
+  gimp_drawable_edit_fill (drawable, options, C_("undo-type", "Clear"));
+
+  g_object_unref (options);
+}
+
+void
+gimp_drawable_edit_fill (GimpDrawable    *drawable,
+                         GimpFillOptions *options,
+                         const gchar     *undo_desc)
+{
+  GimpContext *context;
+  gint         x, y, width, height;
+
+  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
+  g_return_if_fail (gimp_item_is_attached (GIMP_ITEM (drawable)));
+  g_return_if_fail (GIMP_IS_FILL_OPTIONS (options));
+
+  if (! gimp_item_mask_intersect (GIMP_ITEM (drawable),
+                                  &x, &y, &width, &height))
+    {
+      return;  /*  nothing to do, but the fill succeeded  */
+    }
+
+  context = GIMP_CONTEXT (options);
+
+  if (gimp_layer_mode_is_alpha_only (gimp_context_get_paint_mode (context)))
+    {
+      if (! gimp_drawable_has_alpha (drawable) ||
+          ! (gimp_drawable_get_active_mask (drawable) &
+             GIMP_COMPONENT_MASK_ALPHA))
+        {
+          return;  /*  nothing to do, but the fill succeeded  */
+        }
+    }
+
+  if (! undo_desc)
+    undo_desc = gimp_fill_options_get_undo_desc (options);
+
+  /* check if we can fill the drawable's buffer directly */
+  if (gimp_drawable_edit_can_fill_direct (drawable, options))
+    {
+      gimp_drawable_edit_fill_direct (drawable, options, undo_desc);
+
+      gimp_drawable_update (drawable, x, y, width, height);
+    }
+  else
+    {
+      GeglNode           *operation;
+      GimpDrawableFilter *filter;
+      gdouble             opacity;
+      GimpLayerMode       mode;
+      GimpLayerMode       composite_mode;
+
+      opacity        = gimp_context_get_opacity (context);
+      mode           = gimp_context_get_paint_mode (context);
+      composite_mode = gimp_layer_mode_get_paint_composite_mode (mode);
+
+      operation = gegl_node_new_child (NULL,
+                                       "operation",        "gimp:fill-source",
+                                       "options",          options,
+                                       "drawable",         drawable,
+                                       "pattern-offset-x", -x,
+                                       "pattern-offset-y", -y,
+                                       NULL);
+
+      filter = gimp_drawable_filter_new (drawable, undo_desc, operation, NULL);
+
+      gimp_drawable_filter_set_opacity (filter, opacity);
+      gimp_drawable_filter_set_mode    (filter,
+                                        mode,
+                                        GIMP_LAYER_COLOR_SPACE_AUTO,
+                                        GIMP_LAYER_COLOR_SPACE_AUTO,
+                                        composite_mode);
+
+      gimp_drawable_filter_apply  (filter, NULL);
+      gimp_drawable_filter_commit (filter, NULL, FALSE);
+
+      g_object_unref (filter);
+      g_object_unref (operation);
+    }
+}
diff --git a/app/core/gimpdrawable-edit.h b/app/core/gimpdrawable-edit.h
new file mode 100644
index 0000000..a4ecb1c
--- /dev/null
+++ b/app/core/gimpdrawable-edit.h
@@ -0,0 +1,29 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_DRAWABLE_EDIT_H__
+#define __GIMP_DRAWABLE_EDIT_H__
+
+
+void   gimp_drawable_edit_clear (GimpDrawable    *drawable,
+                                 GimpContext     *context);
+void   gimp_drawable_edit_fill  (GimpDrawable    *drawable,
+                                 GimpFillOptions *options,
+                                 const gchar     *undo_desc);
+
+
+#endif  /*  __GIMP_DRAWABLE_EDIT_H__  */
diff --git a/app/core/gimpdrawable-equalize.c b/app/core/gimpdrawable-equalize.c
new file mode 100644
index 0000000..202dc7f
--- /dev/null
+++ b/app/core/gimpdrawable-equalize.c
@@ -0,0 +1,71 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gimpdrawable.h"
+#include "gimpdrawable-equalize.h"
+#include "gimpdrawable-histogram.h"
+#include "gimpdrawable-operation.h"
+#include "gimphistogram.h"
+#include "gimpimage.h"
+#include "gimpselection.h"
+
+#include "gimp-intl.h"
+
+
+void
+gimp_drawable_equalize (GimpDrawable *drawable,
+                        gboolean      mask_only)
+{
+  GimpImage     *image;
+  GimpChannel   *selection;
+  GimpHistogram *histogram;
+  GeglNode      *equalize;
+
+  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
+  g_return_if_fail (gimp_item_is_attached (GIMP_ITEM (drawable)));
+
+  image = gimp_item_get_image (GIMP_ITEM (drawable));
+  selection = gimp_image_get_mask (image);
+
+  histogram = gimp_histogram_new (FALSE);
+  gimp_drawable_calculate_histogram (drawable, histogram, FALSE);
+
+  equalize = gegl_node_new_child (NULL,
+                                  "operation", "gimp:equalize",
+                                  "histogram", histogram,
+                                  NULL);
+
+  if (! mask_only)
+    gimp_selection_suspend (GIMP_SELECTION (selection));
+
+  gimp_drawable_apply_operation (drawable, NULL,
+                                 C_("undo-type", "Equalize"),
+                                 equalize);
+
+  if (! mask_only)
+    gimp_selection_resume (GIMP_SELECTION (selection));
+
+  g_object_unref (equalize);
+  g_object_unref (histogram);
+}
diff --git a/app/core/gimpdrawable-equalize.h b/app/core/gimpdrawable-equalize.h
new file mode 100644
index 0000000..065b83f
--- /dev/null
+++ b/app/core/gimpdrawable-equalize.h
@@ -0,0 +1,26 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_DRAWABLE_EQUALIZE_H__
+#define __GIMP_DRAWABLE_EQUALIZE_H__
+
+
+void   gimp_drawable_equalize (GimpDrawable *drawable,
+                               gboolean      mask_only);
+
+
+#endif  /*  __GIMP_DRAWABLE_EQUALIZE_H__  */
diff --git a/app/core/gimpdrawable-fill.c b/app/core/gimpdrawable-fill.c
new file mode 100644
index 0000000..a596d47
--- /dev/null
+++ b/app/core/gimpdrawable-fill.c
@@ -0,0 +1,279 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <cairo.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpcolor/gimpcolor.h"
+
+#include "core-types.h"
+
+#include "gegl/gimp-babl.h"
+#include "gegl/gimp-gegl-apply-operation.h"
+#include "gegl/gimp-gegl-loops.h"
+#include "gegl/gimp-gegl-utils.h"
+
+#include "operations/layer-modes/gimp-layer-modes.h"
+
+#include "gimp-utils.h"
+#include "gimpbezierdesc.h"
+#include "gimpchannel.h"
+#include "gimpdrawable-fill.h"
+#include "gimperror.h"
+#include "gimpfilloptions.h"
+#include "gimpimage.h"
+#include "gimppattern.h"
+#include "gimppickable.h"
+#include "gimpscanconvert.h"
+
+#include "vectors/gimpvectors.h"
+
+#include "gimp-intl.h"
+
+
+/*  public functions  */
+
+void
+gimp_drawable_fill (GimpDrawable *drawable,
+                    GimpContext  *context,
+                    GimpFillType  fill_type)
+{
+  GimpRGB      color;
+  GimpPattern *pattern;
+
+  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  if (fill_type == GIMP_FILL_TRANSPARENT &&
+      ! gimp_drawable_has_alpha (drawable))
+    {
+      fill_type = GIMP_FILL_BACKGROUND;
+    }
+
+  if (! gimp_get_fill_params (context, fill_type, &color, &pattern, NULL))
+    return;
+
+  gimp_drawable_fill_buffer (drawable,
+                             gimp_drawable_get_buffer (drawable),
+                             &color, pattern, 0, 0);
+
+  gimp_drawable_update (drawable, 0, 0, -1, -1);
+}
+
+void
+gimp_drawable_fill_buffer (GimpDrawable  *drawable,
+                           GeglBuffer    *buffer,
+                           const GimpRGB *color,
+                           GimpPattern   *pattern,
+                           gint           pattern_offset_x,
+                           gint           pattern_offset_y)
+{
+  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
+  g_return_if_fail (GEGL_IS_BUFFER (buffer));
+  g_return_if_fail (color != NULL || pattern != NULL);
+  g_return_if_fail (pattern == NULL || GIMP_IS_PATTERN (pattern));
+
+  if (pattern)
+    {
+      GeglBuffer       *src_buffer;
+      GeglBuffer       *dest_buffer;
+      GimpColorProfile *src_profile;
+      GimpColorProfile *dest_profile;
+
+      src_buffer = gimp_pattern_create_buffer (pattern);
+
+      src_profile  = gimp_babl_format_get_color_profile (
+                       gegl_buffer_get_format (src_buffer));
+      dest_profile = gimp_color_managed_get_color_profile (
+                       GIMP_COLOR_MANAGED (drawable));
+
+      if (gimp_color_transform_can_gegl_copy (src_profile, dest_profile))
+        {
+          dest_buffer = g_object_ref (src_buffer);
+        }
+      else
+        {
+          dest_buffer = gegl_buffer_new (gegl_buffer_get_extent (src_buffer),
+                                         gegl_buffer_get_format (buffer));
+
+          gimp_gegl_convert_color_profile (
+            src_buffer,  NULL, src_profile,
+            dest_buffer, NULL, dest_profile,
+            GIMP_COLOR_RENDERING_INTENT_PERCEPTUAL,
+            TRUE,
+            NULL);
+        }
+
+      gegl_buffer_set_pattern (buffer, NULL, dest_buffer,
+                               pattern_offset_x, pattern_offset_y);
+
+      g_object_unref (src_buffer);
+      g_object_unref (dest_buffer);
+    }
+  else
+    {
+      GimpRGB    image_color;
+      GeglColor *gegl_color;
+
+      gimp_pickable_srgb_to_image_color (GIMP_PICKABLE (drawable),
+                                         color, &image_color);
+
+      if (! gimp_drawable_has_alpha (drawable))
+        gimp_rgb_set_alpha (&image_color, 1.0);
+
+      gegl_color = gimp_gegl_color_new (&image_color);
+      gegl_buffer_set_color (buffer, NULL, gegl_color);
+      g_object_unref (gegl_color);
+    }
+}
+
+void
+gimp_drawable_fill_boundary (GimpDrawable       *drawable,
+                             GimpFillOptions    *options,
+                             const GimpBoundSeg *bound_segs,
+                             gint                n_bound_segs,
+                             gint                offset_x,
+                             gint                offset_y,
+                             gboolean            push_undo)
+{
+  GimpScanConvert *scan_convert;
+
+  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
+  g_return_if_fail (gimp_item_is_attached (GIMP_ITEM (drawable)));
+  g_return_if_fail (GIMP_IS_FILL_OPTIONS (options));
+  g_return_if_fail (bound_segs == NULL || n_bound_segs != 0);
+  g_return_if_fail (gimp_fill_options_get_style (options) !=
+                    GIMP_FILL_STYLE_PATTERN ||
+                    gimp_context_get_pattern (GIMP_CONTEXT (options)) != NULL);
+
+  scan_convert = gimp_scan_convert_new_from_boundary (bound_segs, n_bound_segs,
+                                                      offset_x, offset_y);
+
+  if (scan_convert)
+    {
+      gimp_drawable_fill_scan_convert (drawable, options,
+                                       scan_convert, push_undo);
+      gimp_scan_convert_free (scan_convert);
+    }
+}
+
+gboolean
+gimp_drawable_fill_vectors (GimpDrawable     *drawable,
+                            GimpFillOptions  *options,
+                            GimpVectors      *vectors,
+                            gboolean          push_undo,
+                            GError          **error)
+{
+  const GimpBezierDesc *bezier;
+
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), FALSE);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (drawable)), FALSE);
+  g_return_val_if_fail (GIMP_IS_FILL_OPTIONS (options), FALSE);
+  g_return_val_if_fail (GIMP_IS_VECTORS (vectors), FALSE);
+  g_return_val_if_fail (gimp_fill_options_get_style (options) !=
+                        GIMP_FILL_STYLE_PATTERN ||
+                        gimp_context_get_pattern (GIMP_CONTEXT (options)) != NULL,
+                        FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  bezier = gimp_vectors_get_bezier (vectors);
+
+  if (bezier && bezier->num_data > 4)
+    {
+      GimpScanConvert *scan_convert = gimp_scan_convert_new ();
+
+      gimp_scan_convert_add_bezier (scan_convert, bezier);
+      gimp_drawable_fill_scan_convert (drawable, options,
+                                       scan_convert, push_undo);
+
+      gimp_scan_convert_free (scan_convert);
+
+      return TRUE;
+    }
+
+  g_set_error_literal (error, GIMP_ERROR, GIMP_FAILED,
+                       _("Not enough points to fill"));
+
+  return FALSE;
+}
+
+void
+gimp_drawable_fill_scan_convert (GimpDrawable    *drawable,
+                                 GimpFillOptions *options,
+                                 GimpScanConvert *scan_convert,
+                                 gboolean         push_undo)
+{
+  GimpContext *context;
+  GeglBuffer  *buffer;
+  GeglBuffer  *mask_buffer;
+  gint         x, y, w, h;
+  gint         off_x;
+  gint         off_y;
+
+  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
+  g_return_if_fail (gimp_item_is_attached (GIMP_ITEM (drawable)));
+  g_return_if_fail (GIMP_IS_FILL_OPTIONS (options));
+  g_return_if_fail (scan_convert != NULL);
+  g_return_if_fail (gimp_fill_options_get_style (options) !=
+                    GIMP_FILL_STYLE_PATTERN ||
+                    gimp_context_get_pattern (GIMP_CONTEXT (options)) != NULL);
+
+  context = GIMP_CONTEXT (options);
+
+  if (! gimp_item_mask_intersect (GIMP_ITEM (drawable), &x, &y, &w, &h))
+    return;
+
+  /* fill a 1-bpp GeglBuffer with black, this will describe the shape
+   * of the stroke.
+   */
+  mask_buffer = gegl_buffer_new (GEGL_RECTANGLE (0, 0, w, h),
+                                 babl_format ("Y u8"));
+
+  /* render the stroke into it */
+  gimp_item_get_offset (GIMP_ITEM (drawable), &off_x, &off_y);
+
+  gimp_scan_convert_render (scan_convert, mask_buffer,
+                            x + off_x, y + off_y,
+                            gimp_fill_options_get_antialias (options));
+
+  buffer = gimp_fill_options_create_buffer (options, drawable,
+                                            GEGL_RECTANGLE (0, 0, w, h),
+                                            -x, -y);
+
+  gimp_gegl_apply_opacity (buffer, NULL, NULL, buffer,
+                           mask_buffer, 0, 0, 1.0);
+  g_object_unref (mask_buffer);
+
+  /* Apply to drawable */
+  gimp_drawable_apply_buffer (drawable, buffer,
+                              GEGL_RECTANGLE (0, 0, w, h),
+                              push_undo, C_("undo-type", "Render Stroke"),
+                              gimp_context_get_opacity (context),
+                              gimp_context_get_paint_mode (context),
+                              GIMP_LAYER_COLOR_SPACE_AUTO,
+                              GIMP_LAYER_COLOR_SPACE_AUTO,
+                              gimp_layer_mode_get_paint_composite_mode (
+                                gimp_context_get_paint_mode (context)),
+                              NULL, x, y);
+
+  g_object_unref (buffer);
+
+  gimp_drawable_update (drawable, x, y, w, h);
+}
diff --git a/app/core/gimpdrawable-fill.h b/app/core/gimpdrawable-fill.h
new file mode 100644
index 0000000..d85d5bb
--- /dev/null
+++ b/app/core/gimpdrawable-fill.h
@@ -0,0 +1,60 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_DRAWABLE_FILL_H__
+#define __GIMP_DRAWABLE_FILL_H__
+
+
+/*  Lowlevel API that is used for initializing entire drawables and
+ *  buffers before they are used in images, they don't push an undo.
+ */
+
+void       gimp_drawable_fill              (GimpDrawable        *drawable,
+                                            GimpContext         *context,
+                                            GimpFillType         fill_type);
+void       gimp_drawable_fill_buffer       (GimpDrawable        *drawable,
+                                            GeglBuffer          *buffer,
+                                            const GimpRGB       *color,
+                                            GimpPattern         *pattern,
+                                            gint                 pattern_offset_x,
+                                            gint                 pattern_offset_y);
+
+
+/*  Proper API that is used for actual editing (not just initializing)
+ */
+
+void       gimp_drawable_fill_boundary     (GimpDrawable        *drawable,
+                                            GimpFillOptions     *options,
+                                            const GimpBoundSeg  *bound_segs,
+                                            gint                 n_bound_segs,
+                                            gint                 offset_x,
+                                            gint                 offset_y,
+                                            gboolean             push_undo);
+
+gboolean   gimp_drawable_fill_vectors      (GimpDrawable        *drawable,
+                                            GimpFillOptions     *options,
+                                            GimpVectors         *vectors,
+                                            gboolean             push_undo,
+                                            GError             **error);
+
+void       gimp_drawable_fill_scan_convert (GimpDrawable        *drawable,
+                                            GimpFillOptions     *options,
+                                            GimpScanConvert     *scan_convert,
+                                            gboolean             push_undo);
+
+
+#endif /* __GIMP_DRAWABLE_FILL_H__ */
diff --git a/app/core/gimpdrawable-filters.c b/app/core/gimpdrawable-filters.c
new file mode 100644
index 0000000..762a870
--- /dev/null
+++ b/app/core/gimpdrawable-filters.c
@@ -0,0 +1,343 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpdrawable-filters.c
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+#include <cairo.h>
+
+#include "core-types.h"
+
+#include "gegl/gimpapplicator.h"
+#include "gegl/gimp-gegl-apply-operation.h"
+#include "gegl/gimp-gegl-loops.h"
+
+#include "gimp.h"
+#include "gimp-utils.h"
+#include "gimpdrawable.h"
+#include "gimpdrawable-filters.h"
+#include "gimpdrawable-private.h"
+#include "gimpfilter.h"
+#include "gimpfilterstack.h"
+#include "gimpimage.h"
+#include "gimpimage-undo.h"
+#include "gimplayer.h"
+#include "gimpprogress.h"
+#include "gimpprojection.h"
+
+
+GimpContainer *
+gimp_drawable_get_filters (GimpDrawable *drawable)
+{
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
+
+  return drawable->private->filter_stack;
+}
+
+gboolean
+gimp_drawable_has_filters (GimpDrawable *drawable)
+{
+  GList *list;
+
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), FALSE);
+
+  for (list = GIMP_LIST (drawable->private->filter_stack)->queue->head;
+       list;
+       list = g_list_next (list))
+    {
+      GimpFilter *filter = list->data;
+
+      if (gimp_filter_get_active (filter))
+        return TRUE;
+    }
+
+  return FALSE;
+}
+
+void
+gimp_drawable_add_filter (GimpDrawable *drawable,
+                          GimpFilter   *filter)
+{
+  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
+  g_return_if_fail (GIMP_IS_FILTER (filter));
+  g_return_if_fail (gimp_drawable_has_filter (drawable, filter) == FALSE);
+
+  gimp_container_add (drawable->private->filter_stack,
+                      GIMP_OBJECT (filter));
+}
+
+void
+gimp_drawable_remove_filter (GimpDrawable *drawable,
+                             GimpFilter   *filter)
+{
+  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
+  g_return_if_fail (GIMP_IS_FILTER (filter));
+  g_return_if_fail (gimp_drawable_has_filter (drawable, filter) == TRUE);
+
+  gimp_container_remove (drawable->private->filter_stack,
+                         GIMP_OBJECT (filter));
+}
+
+gboolean
+gimp_drawable_has_filter (GimpDrawable *drawable,
+                          GimpFilter   *filter)
+{
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), FALSE);
+  g_return_val_if_fail (GIMP_IS_FILTER (filter), FALSE);
+
+  return gimp_container_have (drawable->private->filter_stack,
+                              GIMP_OBJECT (filter));
+}
+
+gboolean
+gimp_drawable_merge_filter (GimpDrawable *drawable,
+                            GimpFilter   *filter,
+                            GimpProgress *progress,
+                            const gchar  *undo_desc,
+                            const Babl   *format,
+                            gboolean      clip,
+                            gboolean      cancellable,
+                            gboolean      update)
+{
+  GimpImage      *image;
+  GimpApplicator *applicator;
+  gboolean        applicator_cache         = FALSE;
+  const Babl     *applicator_output_format = NULL;
+  GeglBuffer     *buffer                   = NULL;
+  GeglBuffer     *dest_buffer;
+  GeglBuffer     *undo_buffer              = NULL;
+  GeglRectangle   undo_rect;
+  GeglBuffer     *cache                    = NULL;
+  GeglRectangle  *rects                    = NULL;
+  gint            n_rects                  = 0;
+  GeglRectangle   rect;
+  gboolean        success                  = TRUE;
+
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), FALSE);
+  g_return_val_if_fail (GIMP_IS_FILTER (filter), FALSE);
+  g_return_val_if_fail (progress == NULL || GIMP_IS_PROGRESS (progress), FALSE);
+
+  image       = gimp_item_get_image (GIMP_ITEM (drawable));
+  applicator  = gimp_filter_get_applicator (filter);
+  dest_buffer = gimp_drawable_get_buffer (drawable);
+
+  if (! format)
+    format = gimp_drawable_get_format (drawable);
+
+  rect = gegl_node_get_bounding_box (gimp_filter_get_node (filter));
+
+  if (! clip && gegl_rectangle_equal (&rect,
+                                      gegl_buffer_get_extent (dest_buffer)))
+    {
+      clip = TRUE;
+    }
+
+  if (clip)
+    {
+      if (! gimp_item_mask_intersect (GIMP_ITEM (drawable),
+                                      &rect.x, &rect.y,
+                                      &rect.width, &rect.height))
+        {
+          return TRUE;
+        }
+
+      if (format != gimp_drawable_get_format (drawable))
+        {
+          buffer = gegl_buffer_new (gegl_buffer_get_extent (dest_buffer),
+                                    format);
+
+          dest_buffer = buffer;
+        }
+    }
+  else
+    {
+      buffer = gegl_buffer_new (GEGL_RECTANGLE (0, 0, rect.width, rect.height),
+                                format);
+
+      dest_buffer = g_object_new (GEGL_TYPE_BUFFER,
+                                  "source",  buffer,
+                                  "shift-x", -rect.x,
+                                  "shift-y", -rect.y,
+                                  NULL);
+    }
+
+  if (applicator)
+    {
+      const GeglRectangle *crop_rect;
+
+      crop_rect = gimp_applicator_get_crop (applicator);
+
+      if (crop_rect && ! gegl_rectangle_intersect (&rect, &rect, crop_rect))
+        return TRUE;
+
+      /*  the cache and its valid rectangles are the region that
+       *  has already been processed by this applicator.
+       */
+      cache = gimp_applicator_get_cache_buffer (applicator,
+                                                &rects, &n_rects);
+
+      /*  skip the cache and output-format conversion while processing
+       *  the remaining area, so that the result is written directly to
+       *  the drawable's buffer.
+       */
+      applicator_cache         = gimp_applicator_get_cache (applicator);
+      applicator_output_format = gimp_applicator_get_output_format (applicator);
+
+      gimp_applicator_set_cache (applicator, FALSE);
+      if (applicator_output_format == format)
+        gimp_applicator_set_output_format (applicator, NULL);
+    }
+
+  if (! buffer)
+    {
+      gegl_rectangle_align_to_buffer (
+        &undo_rect,
+        &rect,
+        gimp_drawable_get_buffer (drawable),
+        GEGL_RECTANGLE_ALIGNMENT_SUPERSET);
+
+      undo_buffer = gegl_buffer_new (GEGL_RECTANGLE (0, 0,
+                                                     undo_rect.width,
+                                                     undo_rect.height),
+                                     gimp_drawable_get_format (drawable));
+
+      gimp_gegl_buffer_copy (gimp_drawable_get_buffer (drawable),
+                             &undo_rect,
+                             GEGL_ABYSS_NONE,
+                             undo_buffer,
+                             GEGL_RECTANGLE (0, 0, 0, 0));
+    }
+
+  gimp_projection_stop_rendering (gimp_image_get_projection (image));
+
+  /* make sure we have a source node - this connects the filter stack to the
+   * underlying source node
+   */
+  (void) gimp_drawable_get_source_node (drawable);
+
+  if (gimp_gegl_apply_cached_operation (gimp_drawable_get_buffer (drawable),
+                                        progress, undo_desc,
+                                        gimp_filter_get_node (filter), FALSE,
+                                        dest_buffer, &rect, FALSE,
+                                        cache, rects, n_rects,
+                                        cancellable))
+    {
+      /*  finished successfully  */
+
+      if (clip)
+        {
+          if (buffer)
+            {
+              gimp_drawable_set_buffer_full (drawable,
+                                             TRUE, undo_desc,
+                                             buffer, NULL,
+                                             FALSE);
+            }
+          else
+            {
+              gimp_drawable_push_undo (drawable, undo_desc, undo_buffer,
+                                       undo_rect.x, undo_rect.y,
+                                       undo_rect.width, undo_rect.height);
+            }
+        }
+      else
+        {
+          GimpLayerMask *mask = NULL;
+          gint           offset_x;
+          gint           offset_y;
+
+          gimp_item_get_offset (GIMP_ITEM (drawable), &offset_x, &offset_y);
+
+          if (GIMP_IS_LAYER (drawable))
+            mask = gimp_layer_get_mask (GIMP_LAYER (drawable));
+
+          if (mask)
+            {
+              gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_DRAWABLE_MOD,
+                                           undo_desc);
+            }
+
+          gimp_drawable_set_buffer_full (
+            drawable, TRUE, undo_desc, buffer,
+            GEGL_RECTANGLE (offset_x + rect.x, offset_y + rect.y, 0, 0),
+            FALSE);
+
+          if (mask)
+            {
+              gimp_item_resize (GIMP_ITEM (mask),
+                                gimp_get_default_context (image->gimp),
+                                GIMP_FILL_TRANSPARENT,
+                                rect.width, rect.height,
+                                -rect.x, -rect.y);
+
+              gimp_image_undo_group_end (image);
+            }
+        }
+    }
+  else
+    {
+      /*  canceled by the user  */
+
+      if (clip)
+        {
+          gimp_gegl_buffer_copy (undo_buffer,
+                                 GEGL_RECTANGLE (0, 0,
+                                                 undo_rect.width,
+                                                 undo_rect.height),
+                                 GEGL_ABYSS_NONE,
+                                 gimp_drawable_get_buffer (drawable),
+                                 &undo_rect);
+        }
+
+      success = FALSE;
+    }
+
+  if (clip)
+    {
+      g_clear_object (&undo_buffer);
+      g_clear_object (&buffer);
+    }
+  else
+    {
+      g_object_unref (buffer);
+      g_object_unref (dest_buffer);
+    }
+
+  if (cache)
+    {
+      g_object_unref (cache);
+      g_free (rects);
+    }
+
+  if (applicator)
+    {
+      gimp_applicator_set_cache (applicator, applicator_cache);
+      gimp_applicator_set_output_format (applicator, applicator_output_format);
+    }
+
+  if (update)
+    {
+      gimp_drawable_update (drawable,
+                            rect.x, rect.y,
+                            rect.width, rect.height);
+    }
+
+  return success;
+}
diff --git a/app/core/gimpdrawable-filters.h b/app/core/gimpdrawable-filters.h
new file mode 100644
index 0000000..504d402
--- /dev/null
+++ b/app/core/gimpdrawable-filters.h
@@ -0,0 +1,46 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpdrawable-filters.h
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_DRAWABLE_FILTERS_H__
+#define __GIMP_DRAWABLE_FILTERS_H__
+
+
+GimpContainer * gimp_drawable_get_filters   (GimpDrawable *drawable);
+
+gboolean        gimp_drawable_has_filters   (GimpDrawable *drawable);
+
+void            gimp_drawable_add_filter    (GimpDrawable *drawable,
+                                             GimpFilter   *filter);
+void            gimp_drawable_remove_filter (GimpDrawable *drawable,
+                                             GimpFilter   *filter);
+
+gboolean        gimp_drawable_has_filter    (GimpDrawable *drawable,
+                                             GimpFilter   *filter);
+
+gboolean        gimp_drawable_merge_filter  (GimpDrawable *drawable,
+                                             GimpFilter   *filter,
+                                             GimpProgress *progress,
+                                             const gchar  *undo_desc,
+                                             const Babl   *format,
+                                             gboolean      clip,
+                                             gboolean      cancellable,
+                                             gboolean      update);
+
+
+#endif /* __GIMP_DRAWABLE_FILTERS_H__ */
diff --git a/app/core/gimpdrawable-floating-selection.c b/app/core/gimpdrawable-floating-selection.c
new file mode 100644
index 0000000..71866b1
--- /dev/null
+++ b/app/core/gimpdrawable-floating-selection.c
@@ -0,0 +1,512 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <cairo.h>
+#include <gegl.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "libgimpbase/gimpbase.h"
+
+#include "core-types.h"
+
+#include "gegl/gimpapplicator.h"
+
+#include "gimpchannel.h"
+#include "gimpdrawable-floating-selection.h"
+#include "gimpdrawable-filters.h"
+#include "gimpdrawable-private.h"
+#include "gimpimage.h"
+#include "gimplayer.h"
+
+#include "gimp-log.h"
+
+#include "gimp-intl.h"
+
+
+/*  local function prototypes  */
+
+static void    gimp_drawable_remove_fs_filter             (GimpDrawable      *drawable);
+static void    gimp_drawable_sync_fs_filter               (GimpDrawable      *drawable);
+
+static void    gimp_drawable_fs_notify                    (GObject           *object,
+                                                           const GParamSpec  *pspec,
+                                                           GimpDrawable      *drawable);
+static void    gimp_drawable_fs_lock_position_changed     (GimpDrawable      *signal_drawable,
+                                                           GimpDrawable      *drawable);
+static void    gimp_drawable_fs_format_changed            (GimpDrawable      *signal_drawable,
+                                                           GimpDrawable      *drawable);
+static void    gimp_drawable_fs_affect_changed            (GimpImage         *image,
+                                                           GimpChannelType    channel,
+                                                           GimpDrawable      *drawable);
+static void    gimp_drawable_fs_mask_changed              (GimpImage         *image,
+                                                           GimpDrawable      *drawable);
+static void    gimp_drawable_fs_visibility_changed        (GimpLayer         *fs,
+                                                           GimpDrawable      *drawable);
+static void    gimp_drawable_fs_excludes_backdrop_changed (GimpLayer         *fs,
+                                                           GimpDrawable      *drawable);
+static void    gimp_drawable_fs_bounding_box_changed      (GimpLayer         *fs,
+                                                           GimpDrawable      *drawable);
+static void    gimp_drawable_fs_update                    (GimpLayer         *fs,
+                                                           gint               x,
+                                                           gint               y,
+                                                           gint               width,
+                                                           gint               height,
+                                                           GimpDrawable      *drawable);
+
+
+/*  public functions  */
+
+GimpLayer *
+gimp_drawable_get_floating_sel (GimpDrawable *drawable)
+{
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
+
+  return drawable->private->floating_selection;
+}
+
+void
+gimp_drawable_attach_floating_sel (GimpDrawable *drawable,
+                                   GimpLayer    *fs)
+{
+  GimpImage *image;
+
+  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
+  g_return_if_fail (gimp_item_is_attached (GIMP_ITEM (drawable)));
+  g_return_if_fail (gimp_drawable_get_floating_sel (drawable) == NULL);
+  g_return_if_fail (GIMP_IS_LAYER (fs));
+
+  GIMP_LOG (FLOATING_SELECTION, "%s", G_STRFUNC);
+
+  image = gimp_item_get_image (GIMP_ITEM (drawable));
+
+  drawable->private->floating_selection = fs;
+  gimp_image_set_floating_selection (image, fs);
+
+  /*  clear the selection  */
+  gimp_drawable_invalidate_boundary (GIMP_DRAWABLE (fs));
+
+  gimp_item_bind_visible_to_active (GIMP_ITEM (fs), FALSE);
+  gimp_filter_set_active (GIMP_FILTER (fs), FALSE);
+
+  _gimp_drawable_add_floating_sel_filter (drawable);
+
+  g_signal_connect (fs, "visibility-changed",
+                    G_CALLBACK (gimp_drawable_fs_visibility_changed),
+                    drawable);
+  g_signal_connect (fs, "excludes-backdrop-changed",
+                    G_CALLBACK (gimp_drawable_fs_excludes_backdrop_changed),
+                    drawable);
+  g_signal_connect (fs, "bounding-box-changed",
+                    G_CALLBACK (gimp_drawable_fs_bounding_box_changed),
+                    drawable);
+  g_signal_connect (fs, "update",
+                    G_CALLBACK (gimp_drawable_fs_update),
+                    drawable);
+
+  gimp_drawable_fs_update (fs,
+                           0, 0,
+                           gimp_item_get_width  (GIMP_ITEM (fs)),
+                           gimp_item_get_height (GIMP_ITEM (fs)),
+                           drawable);
+}
+
+void
+gimp_drawable_detach_floating_sel (GimpDrawable *drawable)
+{
+  GimpImage *image;
+  GimpLayer *fs;
+
+  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
+  g_return_if_fail (gimp_drawable_get_floating_sel (drawable) != NULL);
+
+  GIMP_LOG (FLOATING_SELECTION, "%s", G_STRFUNC);
+
+  image = gimp_item_get_image (GIMP_ITEM (drawable));
+  fs    = drawable->private->floating_selection;
+
+  gimp_drawable_remove_fs_filter (drawable);
+
+  g_signal_handlers_disconnect_by_func (fs,
+                                        gimp_drawable_fs_visibility_changed,
+                                        drawable);
+  g_signal_handlers_disconnect_by_func (fs,
+                                        gimp_drawable_fs_excludes_backdrop_changed,
+                                        drawable);
+  g_signal_handlers_disconnect_by_func (fs,
+                                        gimp_drawable_fs_bounding_box_changed,
+                                        drawable);
+  g_signal_handlers_disconnect_by_func (fs,
+                                        gimp_drawable_fs_update,
+                                        drawable);
+
+  gimp_drawable_fs_update (fs,
+                           0, 0,
+                           gimp_item_get_width  (GIMP_ITEM (fs)),
+                           gimp_item_get_height (GIMP_ITEM (fs)),
+                           drawable);
+
+  gimp_item_bind_visible_to_active (GIMP_ITEM (fs), TRUE);
+
+  /*  clear the selection  */
+  gimp_drawable_invalidate_boundary (GIMP_DRAWABLE (fs));
+
+  gimp_image_set_floating_selection (image, NULL);
+  drawable->private->floating_selection = NULL;
+}
+
+GimpFilter *
+gimp_drawable_get_floating_sel_filter (GimpDrawable *drawable)
+{
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
+  g_return_val_if_fail (gimp_drawable_get_floating_sel (drawable) != NULL, NULL);
+
+  /* Ensure that the graph is construced before the filter is used.
+   * Otherwise, we rely on the projection to cause the graph to be
+   * constructed, which fails for images that aren't displayed.
+   */
+  gimp_filter_get_node (GIMP_FILTER (drawable));
+
+  return drawable->private->fs_filter;
+}
+
+
+/*  private functions  */
+
+void
+_gimp_drawable_add_floating_sel_filter (GimpDrawable *drawable)
+{
+  GimpDrawablePrivate *private = drawable->private;
+  GimpImage           *image   = gimp_item_get_image (GIMP_ITEM (drawable));
+  GimpLayer           *fs      = gimp_drawable_get_floating_sel (drawable);
+  GeglNode            *node;
+  GeglNode            *fs_source;
+
+  if (! private->source_node)
+    return;
+
+  private->fs_filter = gimp_filter_new (_("Floating Selection"));
+  gimp_viewable_set_icon_name (GIMP_VIEWABLE (private->fs_filter),
+                               "gimp-floating-selection");
+
+  node = gimp_filter_get_node (private->fs_filter);
+
+  fs_source = gimp_drawable_get_source_node (GIMP_DRAWABLE (fs));
+
+  /* rip the fs' source node out of its graph */
+  if (fs->layer_offset_node)
+    {
+      gegl_node_disconnect (fs->layer_offset_node, "input");
+      gegl_node_remove_child (gimp_filter_get_node (GIMP_FILTER (fs)),
+                              fs_source);
+    }
+
+  gegl_node_add_child (node, fs_source);
+
+  private->fs_applicator = gimp_applicator_new (node);
+
+  gimp_filter_set_applicator (private->fs_filter, private->fs_applicator);
+
+  gimp_applicator_set_cache (private->fs_applicator, TRUE);
+
+  private->fs_crop_node = gegl_node_new_child (node,
+                                               "operation", "gegl:nop",
+                                               NULL);
+
+  gegl_node_connect_to (fs_source,             "output",
+                        private->fs_crop_node, "input");
+  gegl_node_connect_to (private->fs_crop_node, "output",
+                        node,                  "aux");
+
+  gimp_drawable_add_filter (drawable, private->fs_filter);
+
+  g_signal_connect (fs, "notify",
+                    G_CALLBACK (gimp_drawable_fs_notify),
+                    drawable);
+  g_signal_connect (drawable, "notify::offset-x",
+                    G_CALLBACK (gimp_drawable_fs_notify),
+                    drawable);
+  g_signal_connect (drawable, "notify::offset-y",
+                    G_CALLBACK (gimp_drawable_fs_notify),
+                    drawable);
+  g_signal_connect (drawable, "lock-position-changed",
+                    G_CALLBACK (gimp_drawable_fs_lock_position_changed),
+                    drawable);
+  g_signal_connect (drawable, "format-changed",
+                    G_CALLBACK (gimp_drawable_fs_format_changed),
+                    drawable);
+  g_signal_connect (image, "component-active-changed",
+                    G_CALLBACK (gimp_drawable_fs_affect_changed),
+                    drawable);
+  g_signal_connect (image, "mask-changed",
+                    G_CALLBACK (gimp_drawable_fs_mask_changed),
+                    drawable);
+
+  gimp_drawable_sync_fs_filter (drawable);
+}
+
+
+/*  private functions  */
+
+static void
+gimp_drawable_remove_fs_filter (GimpDrawable *drawable)
+{
+  GimpDrawablePrivate *private = drawable->private;
+  GimpImage           *image   = gimp_item_get_image (GIMP_ITEM (drawable));
+  GimpLayer           *fs      = gimp_drawable_get_floating_sel (drawable);
+
+  if (private->fs_filter)
+    {
+      GeglNode *node;
+      GeglNode *fs_source;
+
+      g_signal_handlers_disconnect_by_func (fs,
+                                            gimp_drawable_fs_notify,
+                                            drawable);
+      g_signal_handlers_disconnect_by_func (drawable,
+                                            gimp_drawable_fs_notify,
+                                            drawable);
+      g_signal_handlers_disconnect_by_func (drawable,
+                                            gimp_drawable_fs_lock_position_changed,
+                                            drawable);
+      g_signal_handlers_disconnect_by_func (drawable,
+                                            gimp_drawable_fs_format_changed,
+                                            drawable);
+      g_signal_handlers_disconnect_by_func (image,
+                                            gimp_drawable_fs_affect_changed,
+                                            drawable);
+      g_signal_handlers_disconnect_by_func (image,
+                                            gimp_drawable_fs_mask_changed,
+                                            drawable);
+
+      gimp_drawable_remove_filter (drawable, private->fs_filter);
+
+      node = gimp_filter_get_node (private->fs_filter);
+
+      fs_source = gimp_drawable_get_source_node (GIMP_DRAWABLE (fs));
+
+      gegl_node_remove_child (node, fs_source);
+
+      /* plug the fs' source node back into its graph */
+      if (fs->layer_offset_node)
+        {
+          gegl_node_add_child (gimp_filter_get_node (GIMP_FILTER (fs)),
+                               fs_source);
+          gegl_node_connect_to (fs_source,             "output",
+                                fs->layer_offset_node, "input");
+        }
+
+      g_clear_object (&private->fs_filter);
+      g_clear_object (&private->fs_applicator);
+
+      private->fs_crop_node = NULL;
+
+      gimp_drawable_update_bounding_box (drawable);
+    }
+}
+
+static void
+gimp_drawable_sync_fs_filter (GimpDrawable *drawable)
+{
+  GimpDrawablePrivate *private = drawable->private;
+  GimpImage           *image   = gimp_item_get_image (GIMP_ITEM (drawable));
+  GimpChannel         *mask    = gimp_image_get_mask (image);
+  GimpLayer           *fs      = gimp_drawable_get_floating_sel (drawable);
+  gint                 off_x, off_y;
+  gint                 fs_off_x, fs_off_y;
+
+  gimp_filter_set_active (private->fs_filter,
+                          gimp_item_get_visible (GIMP_ITEM (fs)));
+
+  gimp_item_get_offset (GIMP_ITEM (drawable), &off_x, &off_y);
+  gimp_item_get_offset (GIMP_ITEM (fs), &fs_off_x, &fs_off_y);
+
+  if (gimp_item_get_clip (GIMP_ITEM (drawable), GIMP_TRANSFORM_RESIZE_ADJUST) ==
+      GIMP_TRANSFORM_RESIZE_CLIP ||
+      ! gimp_drawable_has_alpha (drawable))
+    {
+      gegl_node_set (
+        private->fs_crop_node,
+        "operation", "gegl:crop",
+        "x",         (gdouble) (off_x - fs_off_x),
+        "y",         (gdouble) (off_y - fs_off_y),
+        "width",     (gdouble) gimp_item_get_width  (GIMP_ITEM (drawable)),
+        "height",    (gdouble) gimp_item_get_height (GIMP_ITEM (drawable)),
+        NULL);
+    }
+  else
+    {
+      gegl_node_set (
+        private->fs_crop_node,
+        "operation", "gegl:nop",
+        NULL);
+    }
+
+  gimp_applicator_set_apply_offset (private->fs_applicator,
+                                    fs_off_x - off_x,
+                                    fs_off_y - off_y);
+
+  if (gimp_channel_is_empty (mask))
+    {
+      gimp_applicator_set_mask_buffer (private->fs_applicator, NULL);
+    }
+  else
+    {
+      GeglBuffer *buffer = gimp_drawable_get_buffer (GIMP_DRAWABLE (mask));
+
+      gimp_applicator_set_mask_buffer (private->fs_applicator, buffer);
+      gimp_applicator_set_mask_offset (private->fs_applicator,
+                                       -off_x, -off_y);
+    }
+
+  gimp_applicator_set_opacity (private->fs_applicator,
+                               gimp_layer_get_opacity (fs));
+  gimp_applicator_set_mode (private->fs_applicator,
+                            gimp_layer_get_mode (fs),
+                            gimp_layer_get_blend_space (fs),
+                            gimp_layer_get_composite_space (fs),
+                            gimp_layer_get_composite_mode (fs));
+  gimp_applicator_set_affect (private->fs_applicator,
+                              gimp_drawable_get_active_mask (drawable));
+  gimp_applicator_set_output_format (private->fs_applicator,
+                                     gimp_drawable_get_format (drawable));
+
+  gimp_drawable_update_bounding_box (drawable);
+}
+
+static void
+gimp_drawable_fs_notify (GObject          *object,
+                         const GParamSpec *pspec,
+                         GimpDrawable     *drawable)
+{
+  if (! strcmp (pspec->name, "offset-x")        ||
+      ! strcmp (pspec->name, "offset-y")        ||
+      ! strcmp (pspec->name, "visible")         ||
+      ! strcmp (pspec->name, "mode")            ||
+      ! strcmp (pspec->name, "blend-space")     ||
+      ! strcmp (pspec->name, "composite-space") ||
+      ! strcmp (pspec->name, "composite-mode")  ||
+      ! strcmp (pspec->name, "opacity"))
+    {
+      gimp_drawable_sync_fs_filter (drawable);
+    }
+}
+
+static void
+gimp_drawable_fs_lock_position_changed (GimpDrawable *signal_drawable,
+                                        GimpDrawable *drawable)
+{
+  GimpLayer *fs = gimp_drawable_get_floating_sel (drawable);
+
+  gimp_drawable_sync_fs_filter (drawable);
+
+  gimp_drawable_update (GIMP_DRAWABLE (fs), 0, 0, -1, -1);
+}
+
+static void
+gimp_drawable_fs_format_changed (GimpDrawable *signal_drawable,
+                                 GimpDrawable *drawable)
+{
+  GimpLayer *fs = gimp_drawable_get_floating_sel (drawable);
+
+  gimp_drawable_sync_fs_filter (drawable);
+
+  gimp_drawable_update (GIMP_DRAWABLE (fs), 0, 0, -1, -1);
+}
+
+static void
+gimp_drawable_fs_affect_changed (GimpImage       *image,
+                                 GimpChannelType  channel,
+                                 GimpDrawable    *drawable)
+{
+  GimpLayer *fs = gimp_drawable_get_floating_sel (drawable);
+
+  gimp_drawable_sync_fs_filter (drawable);
+
+  gimp_drawable_update (GIMP_DRAWABLE (fs), 0, 0, -1, -1);
+}
+
+static void
+gimp_drawable_fs_mask_changed (GimpImage    *image,
+                               GimpDrawable *drawable)
+{
+  GimpLayer *fs = gimp_drawable_get_floating_sel (drawable);
+
+  gimp_drawable_sync_fs_filter (drawable);
+
+  gimp_drawable_update (GIMP_DRAWABLE (fs), 0, 0, -1, -1);
+}
+
+static void
+gimp_drawable_fs_visibility_changed (GimpLayer    *fs,
+                                     GimpDrawable *drawable)
+{
+  if (gimp_layer_get_excludes_backdrop (fs))
+    gimp_drawable_update (drawable, 0, 0, -1, -1);
+  else
+    gimp_drawable_update (GIMP_DRAWABLE (fs), 0, 0, -1, -1);
+}
+
+static void
+gimp_drawable_fs_excludes_backdrop_changed (GimpLayer    *fs,
+                                            GimpDrawable *drawable)
+{
+  if (gimp_item_get_visible (GIMP_ITEM (fs)))
+    gimp_drawable_update (drawable, 0, 0, -1, -1);
+}
+
+static void
+gimp_drawable_fs_bounding_box_changed (GimpLayer    *fs,
+                                       GimpDrawable *drawable)
+{
+  gimp_drawable_update_bounding_box (drawable);
+}
+
+static void
+gimp_drawable_fs_update (GimpLayer    *fs,
+                         gint          x,
+                         gint          y,
+                         gint          width,
+                         gint          height,
+                         GimpDrawable *drawable)
+{
+  GeglRectangle bounding_box;
+  GeglRectangle rect;
+  gint          fs_off_x, fs_off_y;
+  gint          off_x, off_y;
+
+  gimp_item_get_offset (GIMP_ITEM (fs), &fs_off_x, &fs_off_y);
+  gimp_item_get_offset (GIMP_ITEM (drawable), &off_x, &off_y);
+
+  bounding_box = gimp_drawable_get_bounding_box (drawable);
+
+  bounding_box.x += off_x;
+  bounding_box.y += off_y;
+
+  rect.x      = x + fs_off_x;
+  rect.y      = y + fs_off_y;
+  rect.width  = width;
+  rect.height = height;
+
+  if (gegl_rectangle_intersect (&rect, &rect, &bounding_box))
+    {
+      gimp_drawable_update (drawable,
+                            rect.x - off_x, rect.y - off_y,
+                            rect.width, rect.height);
+    }
+}
diff --git a/app/core/gimpdrawable-floating-selection.h b/app/core/gimpdrawable-floating-selection.h
new file mode 100644
index 0000000..336a0cf
--- /dev/null
+++ b/app/core/gimpdrawable-floating-selection.h
@@ -0,0 +1,31 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_DRAWABLE_FLOATING_SELECTION_H__
+#define __GIMP_DRAWABLE_FLOATING_SELECTION_H__
+
+
+GimpLayer  * gimp_drawable_get_floating_sel          (GimpDrawable *drawable);
+void         gimp_drawable_attach_floating_sel       (GimpDrawable *drawable,
+                                                      GimpLayer    *floating_sel);
+void         gimp_drawable_detach_floating_sel       (GimpDrawable *drawable);
+GimpFilter * gimp_drawable_get_floating_sel_filter   (GimpDrawable *drawable);
+
+void         _gimp_drawable_add_floating_sel_filter  (GimpDrawable *drawable);
+
+
+#endif /* __GIMP_DRAWABLE_FLOATING_SELECTION_H__ */
diff --git a/app/core/gimpdrawable-foreground-extract.c b/app/core/gimpdrawable-foreground-extract.c
new file mode 100644
index 0000000..5846363
--- /dev/null
+++ b/app/core/gimpdrawable-foreground-extract.c
@@ -0,0 +1,150 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gio/gio.h>
+#include <gegl.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "libgimpbase/gimpbase.h"
+
+#include "core-types.h"
+
+#include "gegl/gimp-gegl-utils.h"
+
+#include "gimpchannel.h"
+#include "gimpdrawable.h"
+#include "gimpdrawable-foreground-extract.h"
+#include "gimpimage.h"
+#include "gimpprogress.h"
+
+#include "gimp-intl.h"
+
+
+/*  public functions  */
+
+GeglBuffer *
+gimp_drawable_foreground_extract (GimpDrawable      *drawable,
+                                  GimpMattingEngine  engine,
+                                  gint               global_iterations,
+                                  gint               levin_levels,
+                                  gint               levin_active_levels,
+                                  GeglBuffer        *trimap,
+                                  GimpProgress      *progress)
+{
+  GeglBuffer    *drawable_buffer;
+  GeglNode      *gegl;
+  GeglNode      *input_node;
+  GeglNode      *trimap_node;
+  GeglNode      *matting_node;
+  GeglNode      *output_node;
+  GeglBuffer    *buffer;
+  GeglProcessor *processor;
+  gdouble        value;
+  gint           off_x, off_y;
+
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
+  g_return_val_if_fail (GEGL_IS_BUFFER (trimap), NULL);
+  g_return_val_if_fail (progress == NULL || GIMP_IS_PROGRESS (progress), NULL);
+
+  progress = gimp_progress_start (progress, FALSE,
+                                  _("Computing alpha of unknown pixels"));
+
+  drawable_buffer = gimp_drawable_get_buffer (drawable);
+
+  gegl = gegl_node_new ();
+
+  trimap_node = gegl_node_new_child (gegl,
+                                     "operation", "gegl:buffer-source",
+                                     "buffer",    trimap,
+                                     NULL);
+  input_node = gegl_node_new_child (gegl,
+                                    "operation", "gegl:buffer-source",
+                                    "buffer",    drawable_buffer,
+                                    NULL);
+  output_node = gegl_node_new_child (gegl,
+                                     "operation", "gegl:buffer-sink",
+                                     "buffer",    &buffer,
+                                     "format",    NULL,
+                                     NULL);
+
+  if (engine == GIMP_MATTING_ENGINE_GLOBAL)
+    {
+      matting_node = gegl_node_new_child (gegl,
+                                          "operation",  "gegl:matting-global",
+                                          "iterations", global_iterations,
+                                          NULL);
+    }
+  else
+    {
+      matting_node = gegl_node_new_child (gegl,
+                                          "operation",     "gegl:matting-levin",
+                                          "levels",        levin_levels,
+                                          "active_levels", levin_active_levels,
+                                          NULL);
+    }
+
+  gimp_item_get_offset (GIMP_ITEM (drawable), &off_x, &off_y);
+
+  if (off_x || off_y)
+    {
+      GeglNode *pre;
+      GeglNode *post;
+
+      pre = gegl_node_new_child (gegl,
+                                 "operation", "gegl:translate",
+                                 "x", -1.0 * off_x,
+                                 "y", -1.0 * off_y,
+                                 NULL);
+      post = gegl_node_new_child (gegl,
+                                  "operation", "gegl:translate",
+                                  "x", 1.0 * off_x,
+                                  "y", 1.0 * off_y,
+                                  NULL);
+
+      gegl_node_connect_to (trimap_node,   "output", pre, "input");
+      gegl_node_connect_to (pre,  "output", matting_node, "aux");
+      gegl_node_link_many (input_node, matting_node, post, output_node, NULL);
+    }
+  else
+    {
+      gegl_node_connect_to (input_node,   "output",
+                            matting_node, "input");
+      gegl_node_connect_to (trimap_node,  "output",
+                            matting_node, "aux");
+      gegl_node_connect_to (matting_node, "output",
+                            output_node,  "input");
+    }
+
+  processor = gegl_node_new_processor (output_node, NULL);
+
+  while (gegl_processor_work (processor, &value))
+    {
+      if (progress)
+        gimp_progress_set_value (progress, value);
+    }
+
+  if (progress)
+    gimp_progress_end (progress);
+
+  g_object_unref (processor);
+
+  g_object_unref (gegl);
+
+  return buffer;
+}
diff --git a/app/core/gimpdrawable-foreground-extract.h b/app/core/gimpdrawable-foreground-extract.h
new file mode 100644
index 0000000..19e2356
--- /dev/null
+++ b/app/core/gimpdrawable-foreground-extract.h
@@ -0,0 +1,31 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef  __GIMP_DRAWABLE_FOREGROUND_EXTRACT_H__
+#define  __GIMP_DRAWABLE_FOREGROUND_EXTRACT_H__
+
+
+GeglBuffer * gimp_drawable_foreground_extract (GimpDrawable       *drawable,
+                                               GimpMattingEngine   engine,
+                                               gint                global_iterations,
+                                               gint                levin_levels,
+                                               gint                levin_active_levels,
+                                               GeglBuffer         *trimap,
+                                               GimpProgress       *progress);
+
+
+#endif  /*  __GIMP_DRAWABLE_FOREGROUND_EXTRACT_H__  */
diff --git a/app/core/gimpdrawable-gradient.c b/app/core/gimpdrawable-gradient.c
new file mode 100644
index 0000000..2d7cbe8
--- /dev/null
+++ b/app/core/gimpdrawable-gradient.c
@@ -0,0 +1,313 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <cairo.h>
+#include <gegl.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "libgimpmath/gimpmath.h"
+
+#include "core-types.h"
+
+#include "gegl/gimp-gegl-apply-operation.h"
+#include "gegl/gimp-gegl-loops.h"
+#include "gegl/gimp-gegl-utils.h"
+
+#include "operations/layer-modes/gimp-layer-modes.h"
+
+#include "gimp.h"
+#include "gimpchannel.h"
+#include "gimpcontext.h"
+#include "gimpdrawable-gradient.h"
+#include "gimpgradient.h"
+#include "gimpimage.h"
+#include "gimpprogress.h"
+
+#include "gimp-intl.h"
+
+
+/*  public functions  */
+
+void
+gimp_drawable_gradient (GimpDrawable                *drawable,
+                        GimpContext                 *context,
+                        GimpGradient                *gradient,
+                        GeglDistanceMetric           metric,
+                        GimpLayerMode                paint_mode,
+                        GimpGradientType             gradient_type,
+                        gdouble                      opacity,
+                        gdouble                      offset,
+                        GimpRepeatMode               repeat,
+                        gboolean                     reverse,
+                        GimpGradientBlendColorSpace  blend_color_space,
+                        gboolean                     supersample,
+                        gint                         max_depth,
+                        gdouble                      threshold,
+                        gboolean                     dither,
+                        gdouble                      startx,
+                        gdouble                      starty,
+                        gdouble                      endx,
+                        gdouble                      endy,
+                        GimpProgress                *progress)
+{
+  GimpImage  *image;
+  GeglBuffer *buffer;
+  GeglBuffer *shapeburst = NULL;
+  GeglNode   *render;
+  gint        x, y, width, height;
+
+  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
+  g_return_if_fail (gimp_item_is_attached (GIMP_ITEM (drawable)));
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+  g_return_if_fail (GIMP_IS_GRADIENT (gradient));
+  g_return_if_fail (progress == NULL || GIMP_IS_PROGRESS (progress));
+
+  image = gimp_item_get_image (GIMP_ITEM (drawable));
+
+  if (! gimp_item_mask_intersect (GIMP_ITEM (drawable), &x, &y, &width, &height))
+    return;
+
+  gimp_set_busy (image->gimp);
+
+  /*  Always create an alpha temp buf (for generality) */
+  buffer = gegl_buffer_new (GEGL_RECTANGLE (x, y, width, height),
+                            gimp_drawable_get_format_with_alpha (drawable));
+
+  if (gradient_type >= GIMP_GRADIENT_SHAPEBURST_ANGULAR &&
+      gradient_type <= GIMP_GRADIENT_SHAPEBURST_DIMPLED)
+    {
+      shapeburst =
+        gimp_drawable_gradient_shapeburst_distmap (drawable, metric,
+                                                   GEGL_RECTANGLE (x, y, width, height),
+                                                   progress);
+    }
+
+  gimp_drawable_gradient_adjust_coords (drawable,
+                                        gradient_type,
+                                        GEGL_RECTANGLE (x, y, width, height),
+                                        &startx, &starty, &endx, &endy);
+
+  render = gegl_node_new_child (NULL,
+                                "operation",                  "gimp:gradient",
+                                "context",                    context,
+                                "gradient",                   gradient,
+                                "start-x",                    startx,
+                                "start-y",                    starty,
+                                "end-x",                      endx,
+                                "end-y",                      endy,
+                                "gradient-type",              gradient_type,
+                                "gradient-repeat",            repeat,
+                                "offset",                     offset,
+                                "gradient-reverse",           reverse,
+                                "gradient-blend-color-space", blend_color_space,
+                                "supersample",                supersample,
+                                "supersample-depth",          max_depth,
+                                "supersample-threshold",      threshold,
+                                "dither",                     dither,
+                                NULL);
+
+  gimp_gegl_apply_operation (shapeburst, progress, C_("undo-type", "Gradient"),
+                             render,
+                             buffer, GEGL_RECTANGLE (x, y, width, height),
+                             FALSE);
+
+  g_object_unref (render);
+
+  if (shapeburst)
+    g_object_unref (shapeburst);
+
+  gimp_drawable_apply_buffer (drawable, buffer,
+                              GEGL_RECTANGLE (x, y, width, height),
+                              TRUE, C_("undo-type", "Gradient"),
+                              opacity, paint_mode,
+                              GIMP_LAYER_COLOR_SPACE_AUTO,
+                              GIMP_LAYER_COLOR_SPACE_AUTO,
+                              gimp_layer_mode_get_paint_composite_mode (paint_mode),
+                              NULL, x, y);
+
+  gimp_drawable_update (drawable, x, y, width, height);
+
+  g_object_unref (buffer);
+
+  gimp_unset_busy (image->gimp);
+}
+
+GeglBuffer *
+gimp_drawable_gradient_shapeburst_distmap (GimpDrawable        *drawable,
+                                           GeglDistanceMetric   metric,
+                                           const GeglRectangle *region,
+                                           GimpProgress        *progress)
+{
+  GimpChannel *mask;
+  GimpImage   *image;
+  GeglBuffer  *dist_buffer;
+  GeglBuffer  *temp_buffer;
+  GeglNode    *shapeburst;
+
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (drawable)), NULL);
+  g_return_val_if_fail (progress == NULL || GIMP_IS_PROGRESS (progress), NULL);
+
+  image = gimp_item_get_image (GIMP_ITEM (drawable));
+
+  /*  allocate the distance map  */
+  dist_buffer = gegl_buffer_new (region, babl_format ("Y float"));
+
+  /*  allocate the selection mask copy  */
+  temp_buffer = gegl_buffer_new (region, babl_format ("Y float"));
+
+  mask = gimp_image_get_mask (image);
+
+  /*  If the image mask is not empty, use it as the shape burst source  */
+  if (! gimp_channel_is_empty (mask))
+    {
+      gint x, y, width, height;
+      gint off_x, off_y;
+
+      gimp_item_mask_intersect (GIMP_ITEM (drawable), &x, &y, &width, &height);
+      gimp_item_get_offset (GIMP_ITEM (drawable), &off_x, &off_y);
+
+      /*  copy the mask to the temp mask  */
+      gimp_gegl_buffer_copy (
+        gimp_drawable_get_buffer (GIMP_DRAWABLE (mask)),
+        GEGL_RECTANGLE (x + off_x, y + off_y, width, height),
+        GEGL_ABYSS_NONE, temp_buffer, region);
+    }
+  else
+    {
+      /*  If the intended drawable has an alpha channel, use that  */
+      if (gimp_drawable_has_alpha (drawable))
+        {
+          const Babl *component_format;
+
+          component_format = babl_format ("A float");
+
+          /*  extract the aplha into the temp mask  */
+          gegl_buffer_set_format (temp_buffer, component_format);
+          gimp_gegl_buffer_copy (gimp_drawable_get_buffer (drawable), region,
+                                 GEGL_ABYSS_NONE,
+                                 temp_buffer, region);
+          gegl_buffer_set_format (temp_buffer, NULL);
+        }
+      else
+        {
+          GeglColor *white = gegl_color_new ("white");
+
+          /*  Otherwise, just fill the shapeburst to white  */
+          gegl_buffer_set_color (temp_buffer, NULL, white);
+          g_object_unref (white);
+        }
+    }
+
+  shapeburst = gegl_node_new_child (NULL,
+                                    "operation", "gegl:distance-transform",
+                                    "normalize", TRUE,
+                                    "metric",    metric,
+                                    NULL);
+
+  if (progress)
+    gimp_gegl_progress_connect (shapeburst, progress,
+                                _("Calculating distance map"));
+
+  gimp_gegl_apply_operation (temp_buffer, NULL, NULL,
+                             shapeburst,
+                             dist_buffer, region, FALSE);
+
+  g_object_unref (shapeburst);
+
+  g_object_unref (temp_buffer);
+
+  return dist_buffer;
+}
+
+void
+gimp_drawable_gradient_adjust_coords (GimpDrawable        *drawable,
+                                      GimpGradientType     gradient_type,
+                                      const GeglRectangle *region,
+                                      gdouble             *startx,
+                                      gdouble             *starty,
+                                      gdouble             *endx,
+                                      gdouble             *endy)
+{
+  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
+  g_return_if_fail (region != NULL);
+  g_return_if_fail (startx != NULL);
+  g_return_if_fail (starty != NULL);
+  g_return_if_fail (endx != NULL);
+  g_return_if_fail (endy != NULL);
+
+  /* we potentially adjust the gradient coordinates according to the gradient
+   * type, so that in cases where the gradient span is not related to the
+   * segment length, the gradient cache (in GimpOperationGradient) is big
+   * enough not to produce banding.
+   */
+
+  switch (gradient_type)
+    {
+    /* for conical gradients, use a segment with the original origin and
+     * direction, whose length is the circumference of the largest circle
+     * centered at the origin, passing through one of the regions's vertices.
+     */
+    case GIMP_GRADIENT_CONICAL_SYMMETRIC:
+    case GIMP_GRADIENT_CONICAL_ASYMMETRIC:
+      {
+        gdouble     r = 0.0;
+        GimpVector2 v;
+
+        r = MAX (r, hypot (region->x - *startx,
+                           region->y - *starty));
+        r = MAX (r, hypot (region->x + region->width - *startx,
+                           region->y - *starty));
+        r = MAX (r, hypot (region->x - *startx,
+                           region->y + region->height - *starty));
+        r = MAX (r, hypot (region->x + region->width - *startx,
+                           region->y + region->height - *starty));
+
+        /* symmetric conical gradients only span half a revolution, and
+         * therefore require only half the cache size.
+         */
+        if (gradient_type == GIMP_GRADIENT_CONICAL_SYMMETRIC)
+          r /= 2.0;
+
+        gimp_vector2_set (&v, *endx - *startx, *endy - *starty);
+        gimp_vector2_normalize (&v);
+        gimp_vector2_mul (&v, 2.0 * G_PI * r);
+
+        *endx = *startx + v.x;
+        *endy = *starty + v.y;
+      }
+      break;
+
+    /* for shaped gradients, only the segment's length matters; use the
+     * regions's diagonal, which is the largest possible distance between two
+     * points in the region.
+     */
+    case GIMP_GRADIENT_SHAPEBURST_ANGULAR:
+    case GIMP_GRADIENT_SHAPEBURST_SPHERICAL:
+    case GIMP_GRADIENT_SHAPEBURST_DIMPLED:
+      *startx = region->x;
+      *starty = region->y;
+      *endx   = region->x + region->width;
+      *endy   = region->y + region->height;
+      break;
+
+    default:
+      break;
+    }
+}
diff --git a/app/core/gimpdrawable-gradient.h b/app/core/gimpdrawable-gradient.h
new file mode 100644
index 0000000..4f38c8a
--- /dev/null
+++ b/app/core/gimpdrawable-gradient.h
@@ -0,0 +1,57 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef  __GIMP_DRAWABLE_GRADIENT_H__
+#define  __GIMP_DRAWABLE_GRADIENT_H__
+
+
+void         gimp_drawable_gradient                    (GimpDrawable                *drawable,
+                                                        GimpContext                 *context,
+                                                        GimpGradient                *gradient,
+                                                        GeglDistanceMetric           metric,
+                                                        GimpLayerMode                paint_mode,
+                                                        GimpGradientType             gradient_type,
+                                                        gdouble                      opacity,
+                                                        gdouble                      offset,
+                                                        GimpRepeatMode               repeat,
+                                                        gboolean                     reverse,
+                                                        GimpGradientBlendColorSpace  blend_color_space,
+                                                        gboolean                     supersample,
+                                                        gint                         max_depth,
+                                                        gdouble                      threshold,
+                                                        gboolean                     dither,
+                                                        gdouble                      startx,
+                                                        gdouble                      starty,
+                                                        gdouble                      endx,
+                                                        gdouble                      endy,
+                                                        GimpProgress                *progress);
+
+GeglBuffer * gimp_drawable_gradient_shapeburst_distmap (GimpDrawable                *drawable,
+                                                        GeglDistanceMetric           metric,
+                                                        const GeglRectangle         *region,
+                                                        GimpProgress                *progress);
+
+void         gimp_drawable_gradient_adjust_coords      (GimpDrawable                *drawable,
+                                                        GimpGradientType             gradient_type,
+                                                        const GeglRectangle         *region,
+                                                        gdouble                     *startx,
+                                                        gdouble                     *starty,
+                                                        gdouble                     *endx,
+                                                        gdouble                     *endy);
+
+
+#endif /* __GIMP_DRAWABLE_GRADIENT_H__ */
diff --git a/app/core/gimpdrawable-histogram.c b/app/core/gimpdrawable-histogram.c
new file mode 100644
index 0000000..b0be3f5
--- /dev/null
+++ b/app/core/gimpdrawable-histogram.c
@@ -0,0 +1,258 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimphistogram module Copyright (C) 1999 Jay Cox <jaycox@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <cairo.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gegl/gimp-gegl-nodes.h"
+#include "gegl/gimptilehandlervalidate.h"
+
+#include "gimpasync.h"
+#include "gimpchannel.h"
+#include "gimpdrawable-filters.h"
+#include "gimpdrawable-histogram.h"
+#include "gimphistogram.h"
+#include "gimpimage.h"
+#include "gimpprojectable.h"
+
+
+/*  local function prototypes  */
+
+static GimpAsync * gimp_drawable_calculate_histogram_internal (GimpDrawable  *drawable,
+                                                               GimpHistogram *histogram,
+                                                               gboolean       with_filters,
+                                                               gboolean       run_async);
+
+
+/*  private functions  */
+
+
+static GimpAsync *
+gimp_drawable_calculate_histogram_internal (GimpDrawable  *drawable,
+                                            GimpHistogram *histogram,
+                                            gboolean       with_filters,
+                                            gboolean       run_async)
+{
+  GimpAsync   *async = NULL;
+  GimpImage   *image;
+  GimpChannel *mask;
+  gint         x, y, width, height;
+
+  if (! gimp_item_mask_intersect (GIMP_ITEM (drawable), &x, &y, &width, &height))
+    goto end;
+
+  image = gimp_item_get_image (GIMP_ITEM (drawable));
+  mask  = gimp_image_get_mask (image);
+
+  if (FALSE)
+    {
+      GeglNode      *node = gegl_node_new ();
+      GeglNode      *source;
+      GeglNode      *histogram_sink;
+      GeglProcessor *processor;
+
+      if (with_filters)
+        {
+          source = gimp_drawable_get_source_node (drawable);
+        }
+      else
+        {
+          source =
+            gimp_gegl_add_buffer_source (node,
+                                         gimp_drawable_get_buffer (drawable),
+                                         0, 0);
+        }
+
+      histogram_sink =
+        gegl_node_new_child (node,
+                             "operation", "gimp:histogram-sink",
+                             "histogram", histogram,
+                             NULL);
+
+      gegl_node_connect_to (source,         "output",
+                            histogram_sink, "input");
+
+      if (! gimp_channel_is_empty (mask))
+        {
+          GeglNode *mask_source;
+          gint      off_x, off_y;
+
+          g_printerr ("adding mask aux\n");
+
+          gimp_item_get_offset (GIMP_ITEM (drawable), &off_x, &off_y);
+
+          mask_source =
+            gimp_gegl_add_buffer_source (node,
+                                         gimp_drawable_get_buffer (GIMP_DRAWABLE (mask)),
+                                         -off_x, -off_y);
+
+          gegl_node_connect_to (mask_source,    "output",
+                                histogram_sink, "aux");
+        }
+
+      processor = gegl_node_new_processor (histogram_sink,
+                                           GEGL_RECTANGLE (x, y, width, height));
+
+      while (gegl_processor_work (processor, NULL));
+
+      g_object_unref (processor);
+      g_object_unref (node);
+    }
+  else
+    {
+      GeglBuffer      *buffer      = gimp_drawable_get_buffer (drawable);
+      GimpProjectable *projectable = NULL;
+
+      if (with_filters && gimp_drawable_has_filters (drawable))
+        {
+          GimpTileHandlerValidate *validate;
+          GeglNode                *node;
+
+          node = gimp_drawable_get_source_node (drawable);
+
+          buffer = gegl_buffer_new (gegl_buffer_get_extent (buffer),
+                                    gegl_buffer_get_format (buffer));
+
+          validate =
+            GIMP_TILE_HANDLER_VALIDATE (gimp_tile_handler_validate_new (node));
+
+          gimp_tile_handler_validate_assign (validate, buffer);
+
+          g_object_unref (validate);
+
+          gimp_tile_handler_validate_invalidate (validate,
+                                                 gegl_buffer_get_extent (buffer));
+
+#if 0
+          /*  this would keep the buffer updated across drawable or
+           *  filter changes, but the histogram is created in one go
+           *  and doesn't need the signal connection
+           */
+          g_signal_connect_object (node, "invalidated",
+                                   G_CALLBACK (gimp_tile_handler_validate_invalidate),
+                                   validate, G_CONNECT_SWAPPED);
+#endif
+
+          if (GIMP_IS_PROJECTABLE (drawable))
+            projectable = GIMP_PROJECTABLE (drawable);
+        }
+      else
+        {
+          g_object_ref (buffer);
+        }
+
+      if (projectable)
+        gimp_projectable_begin_render (projectable);
+
+      if (! gimp_channel_is_empty (mask))
+        {
+          gint off_x, off_y;
+
+          gimp_item_get_offset (GIMP_ITEM (drawable), &off_x, &off_y);
+
+          if (run_async)
+            {
+              async = gimp_histogram_calculate_async (
+                histogram, buffer,
+                GEGL_RECTANGLE (x, y, width, height),
+                gimp_drawable_get_buffer (GIMP_DRAWABLE (mask)),
+                GEGL_RECTANGLE (x + off_x, y + off_y,
+                                width, height));
+            }
+          else
+            {
+              gimp_histogram_calculate (
+                histogram, buffer,
+                GEGL_RECTANGLE (x, y, width, height),
+                gimp_drawable_get_buffer (GIMP_DRAWABLE (mask)),
+                GEGL_RECTANGLE (x + off_x, y + off_y,
+                                width, height));
+            }
+        }
+      else
+        {
+          if (run_async)
+            {
+              async = gimp_histogram_calculate_async (
+                histogram, buffer,
+                GEGL_RECTANGLE (x, y, width, height),
+                NULL, NULL);
+            }
+          else
+            {
+              gimp_histogram_calculate (
+                histogram, buffer,
+                GEGL_RECTANGLE (x, y, width, height),
+                NULL, NULL);
+            }
+        }
+
+      if (projectable)
+        gimp_projectable_end_render (projectable);
+
+      g_object_unref (buffer);
+    }
+
+end:
+  if (run_async && ! async)
+    {
+      async = gimp_async_new ();
+
+      gimp_async_finish (async, NULL);
+    }
+
+  return async;
+}
+
+
+/*  public functions  */
+
+
+void
+gimp_drawable_calculate_histogram (GimpDrawable  *drawable,
+                                   GimpHistogram *histogram,
+                                   gboolean       with_filters)
+{
+  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
+  g_return_if_fail (gimp_item_is_attached (GIMP_ITEM (drawable)));
+  g_return_if_fail (histogram != NULL);
+
+  gimp_drawable_calculate_histogram_internal (drawable,
+                                              histogram, with_filters,
+                                              FALSE);
+}
+
+GimpAsync *
+gimp_drawable_calculate_histogram_async (GimpDrawable  *drawable,
+                                         GimpHistogram *histogram,
+                                         gboolean       with_filters)
+{
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (drawable)), NULL);
+  g_return_val_if_fail (histogram != NULL, NULL);
+
+  return gimp_drawable_calculate_histogram_internal (drawable,
+                                                     histogram, with_filters,
+                                                     TRUE);
+}
diff --git a/app/core/gimpdrawable-histogram.h b/app/core/gimpdrawable-histogram.h
new file mode 100644
index 0000000..947393a
--- /dev/null
+++ b/app/core/gimpdrawable-histogram.h
@@ -0,0 +1,32 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimphistogram module Copyright (C) 1999 Jay Cox <jaycox@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_DRAWABLE_HISTOGRAM_H__
+#define __GIMP_DRAWABLE_HISTOGRAM_H__
+
+
+void        gimp_drawable_calculate_histogram       (GimpDrawable  *drawable,
+                                                     GimpHistogram *histogram,
+                                                     gboolean       with_filters);
+GimpAsync * gimp_drawable_calculate_histogram_async (GimpDrawable  *drawable,
+                                                     GimpHistogram *histogram,
+                                                     gboolean       with_filters);
+
+
+#endif /* __GIMP_HISTOGRAM_H__ */
diff --git a/app/core/gimpdrawable-levels.c b/app/core/gimpdrawable-levels.c
new file mode 100644
index 0000000..301326b
--- /dev/null
+++ b/app/core/gimpdrawable-levels.c
@@ -0,0 +1,77 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "operations/gimplevelsconfig.h"
+
+#include "gimpdrawable.h"
+#include "gimpdrawable-histogram.h"
+#include "gimpdrawable-levels.h"
+#include "gimpdrawable-operation.h"
+#include "gimphistogram.h"
+#include "gimpprogress.h"
+
+#include "gimp-intl.h"
+
+
+/*  public functions  */
+
+void
+gimp_drawable_levels_stretch (GimpDrawable *drawable,
+                              GimpProgress *progress)
+{
+  GimpLevelsConfig *config;
+  GimpHistogram    *histogram;
+  GeglNode         *levels;
+
+  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
+  g_return_if_fail (gimp_item_is_attached (GIMP_ITEM (drawable)));
+  g_return_if_fail (progress == NULL || GIMP_IS_PROGRESS (progress));
+
+  if (! gimp_item_mask_intersect (GIMP_ITEM (drawable), NULL, NULL, NULL, NULL))
+    return;
+
+  config = g_object_new (GIMP_TYPE_LEVELS_CONFIG, NULL);
+
+  histogram = gimp_histogram_new (FALSE);
+  gimp_drawable_calculate_histogram (drawable, histogram, FALSE);
+
+  gimp_levels_config_stretch (config, histogram,
+                              gimp_drawable_is_rgb (drawable));
+
+  g_object_unref (histogram);
+
+  levels = g_object_new (GEGL_TYPE_NODE,
+                         "operation", "gimp:levels",
+                         NULL);
+
+  gegl_node_set (levels,
+                 "config", config,
+                 NULL);
+
+  gimp_drawable_apply_operation (drawable, progress, _("Levels"),
+                                 levels);
+
+  g_object_unref (levels);
+  g_object_unref (config);
+}
diff --git a/app/core/gimpdrawable-levels.h b/app/core/gimpdrawable-levels.h
new file mode 100644
index 0000000..22011c1
--- /dev/null
+++ b/app/core/gimpdrawable-levels.h
@@ -0,0 +1,26 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_DRAWABLE_LEVELS_H__
+#define __GIMP_DRAWABLE_LEVELS_H__
+
+
+void   gimp_drawable_levels_stretch (GimpDrawable *drawable,
+                                     GimpProgress *progress);
+
+
+#endif  /*  __GIMP_DRAWABLE_LEVELS_H__  */
diff --git a/app/core/gimpdrawable-offset.c b/app/core/gimpdrawable-offset.c
new file mode 100644
index 0000000..b7f5eb2
--- /dev/null
+++ b/app/core/gimpdrawable-offset.c
@@ -0,0 +1,83 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <cairo.h>
+#include <gegl.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "core-types.h"
+
+#include "gimp.h"
+#include "gimpcontext.h"
+#include "gimpdrawable.h"
+#include "gimpdrawable-offset.h"
+#include "gimpdrawable-operation.h"
+
+#include "gimp-intl.h"
+
+
+void
+gimp_drawable_offset (GimpDrawable   *drawable,
+                      GimpContext    *context,
+                      gboolean        wrap_around,
+                      GimpOffsetType  fill_type,
+                      gint            offset_x,
+                      gint            offset_y)
+{
+  GeglNode *node;
+  gint      width;
+  gint      height;
+
+  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  if (! gimp_item_mask_intersect (GIMP_ITEM (drawable),
+                                  NULL, NULL, &width, &height))
+    {
+      return;
+    }
+
+  if (wrap_around)
+    fill_type = GIMP_OFFSET_WRAP_AROUND;
+
+  if (fill_type == GIMP_OFFSET_WRAP_AROUND)
+    {
+      offset_x %= width;
+      offset_y %= height;
+    }
+
+  if (offset_x == 0 && offset_y == 0)
+    return;
+
+  node = gegl_node_new_child (NULL,
+                              "operation", "gimp:offset",
+                              "context", context,
+                              "type",    fill_type,
+                              "x",       offset_x,
+                              "y",       offset_y,
+                              NULL);
+
+  gimp_drawable_apply_operation (drawable, NULL,
+                                 C_("undo-type", "Offset Drawable"),
+                                 node);
+
+  g_object_unref (node);
+}
diff --git a/app/core/gimpdrawable-offset.h b/app/core/gimpdrawable-offset.h
new file mode 100644
index 0000000..6629150
--- /dev/null
+++ b/app/core/gimpdrawable-offset.h
@@ -0,0 +1,30 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_DRAWABLE_OFFSET_H__
+#define __GIMP_DRAWABLE_OFFSET_H__
+
+
+void   gimp_drawable_offset (GimpDrawable   *drawable,
+                             GimpContext    *context,
+                             gboolean        wrap_around,
+                             GimpOffsetType  fill_type,
+                             gint            offset_x,
+                             gint            offset_y);
+
+
+#endif  /*  __GIMP_DRAWABLE_OFFSET_H__  */
diff --git a/app/core/gimpdrawable-operation.c b/app/core/gimpdrawable-operation.c
new file mode 100644
index 0000000..fdda286
--- /dev/null
+++ b/app/core/gimpdrawable-operation.c
@@ -0,0 +1,128 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpdrawable-operation.c
+ * Copyright (C) 2007 Øyvind Kolås <pippin@gimp.org>
+ *                    Sven Neumann <sven@gimp.org>
+ *                    Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gegl/gimp-gegl-utils.h"
+
+#include "operations/gimp-operation-config.h"
+#include "operations/gimpoperationsettings.h"
+
+#include "gimpdrawable.h"
+#include "gimpdrawable-operation.h"
+#include "gimpdrawablefilter.h"
+#include "gimpprogress.h"
+#include "gimpsettings.h"
+
+
+/*  public functions  */
+
+void
+gimp_drawable_apply_operation (GimpDrawable *drawable,
+                               GimpProgress *progress,
+                               const gchar  *undo_desc,
+                               GeglNode     *operation)
+{
+  gimp_drawable_apply_operation_with_config (drawable,
+                                             progress, undo_desc,
+                                             operation, NULL);
+}
+
+void
+gimp_drawable_apply_operation_with_config (GimpDrawable *drawable,
+                                           GimpProgress *progress,
+                                           const gchar  *undo_desc,
+                                           GeglNode     *operation,
+                                           GObject      *config)
+{
+  GimpDrawableFilter *filter;
+
+  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
+  g_return_if_fail (gimp_item_is_attached (GIMP_ITEM (drawable)));
+  g_return_if_fail (progress == NULL || GIMP_IS_PROGRESS (progress));
+  g_return_if_fail (undo_desc != NULL);
+  g_return_if_fail (GEGL_IS_NODE (operation));
+  g_return_if_fail (config == NULL || GIMP_IS_OPERATION_SETTINGS (config));
+
+  if (! gimp_item_mask_intersect (GIMP_ITEM (drawable),
+                                  NULL, NULL, NULL, NULL))
+    {
+      return;
+    }
+
+  filter = gimp_drawable_filter_new (drawable, undo_desc, operation, NULL);
+
+  gimp_drawable_filter_set_add_alpha (filter,
+                                      gimp_gegl_node_has_key (operation,
+                                                              "needs-alpha"));
+
+  if (config)
+    {
+      gimp_operation_config_sync_node (config, operation);
+
+      gimp_operation_settings_sync_drawable_filter (
+        GIMP_OPERATION_SETTINGS (config), filter);
+    }
+
+  gimp_drawable_filter_apply  (filter, NULL);
+  gimp_drawable_filter_commit (filter, progress, TRUE);
+
+  g_object_unref (filter);
+
+  if (progress)
+    gimp_progress_end (progress);
+}
+
+void
+gimp_drawable_apply_operation_by_name (GimpDrawable *drawable,
+                                       GimpProgress *progress,
+                                       const gchar  *undo_desc,
+                                       const gchar  *operation_type,
+                                       GObject      *config)
+{
+  GeglNode *node;
+
+  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
+  g_return_if_fail (gimp_item_is_attached (GIMP_ITEM (drawable)));
+  g_return_if_fail (progress == NULL || GIMP_IS_PROGRESS (progress));
+  g_return_if_fail (undo_desc != NULL);
+  g_return_if_fail (operation_type != NULL);
+  g_return_if_fail (config == NULL || GIMP_IS_SETTINGS (config));
+
+  node = g_object_new (GEGL_TYPE_NODE,
+                       "operation", operation_type,
+                       NULL);
+
+  if (config)
+    gegl_node_set (node,
+                   "config", config,
+                   NULL);
+
+  gimp_drawable_apply_operation (drawable, progress, undo_desc, node);
+
+  g_object_unref (node);
+}
diff --git a/app/core/gimpdrawable-operation.h b/app/core/gimpdrawable-operation.h
new file mode 100644
index 0000000..6ca381f
--- /dev/null
+++ b/app/core/gimpdrawable-operation.h
@@ -0,0 +1,43 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpdrawable-operation.h
+ * Copyright (C) 2007 Øyvind Kolås <pippin@gimp.org>
+ *                    Sven Neumann <sven@gimp.org>
+ *                    Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_DRAWABLE_OPERATION_H__
+#define __GIMP_DRAWABLE_OPERATION_H__
+
+
+void   gimp_drawable_apply_operation             (GimpDrawable *drawable,
+                                                  GimpProgress *progress,
+                                                  const gchar  *undo_desc,
+                                                  GeglNode     *operation);
+void   gimp_drawable_apply_operation_with_config (GimpDrawable *drawable,
+                                                  GimpProgress *progress,
+                                                  const gchar  *undo_desc,
+                                                  GeglNode     *operation,
+                                                  GObject      *config);
+void   gimp_drawable_apply_operation_by_name     (GimpDrawable *drawable,
+                                                  GimpProgress *progress,
+                                                  const gchar  *undo_desc,
+                                                  const gchar  *operation_type,
+                                                  GObject      *config);
+
+
+#endif /* __GIMP_DRAWABLE_OPERATION_H__ */
diff --git a/app/core/gimpdrawable-preview.c b/app/core/gimpdrawable-preview.c
new file mode 100644
index 0000000..28ae1e2
--- /dev/null
+++ b/app/core/gimpdrawable-preview.c
@@ -0,0 +1,492 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <cairo.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpcolor/gimpcolor.h"
+#include "libgimpmath/gimpmath.h"
+
+#include "core-types.h"
+
+#include "config/gimpcoreconfig.h"
+
+#include "gegl/gimp-babl.h"
+#include "gegl/gimp-gegl-loops.h"
+#include "gegl/gimptilehandlervalidate.h"
+
+#include "gimp.h"
+#include "gimp-parallel.h"
+#include "gimp-utils.h"
+#include "gimpasync.h"
+#include "gimpchannel.h"
+#include "gimpchunkiterator.h"
+#include "gimpimage.h"
+#include "gimpimage-color-profile.h"
+#include "gimpdrawable-preview.h"
+#include "gimpdrawable-private.h"
+#include "gimplayer.h"
+#include "gimptempbuf.h"
+
+#include "gimp-priorities.h"
+
+
+typedef struct
+{
+  const Babl        *format;
+  GeglBuffer        *buffer;
+  GeglRectangle      rect;
+  gdouble            scale;
+
+  GimpChunkIterator *iter;
+} SubPreviewData;
+
+
+/*  local function prototypes  */
+
+static SubPreviewData * sub_preview_data_new  (const Babl          *format,
+                                               GeglBuffer          *buffer,
+                                               const GeglRectangle *rect,
+                                               gdouble              scale);
+static void             sub_preview_data_free (SubPreviewData      *data);
+
+
+
+/*  private functions  */
+
+
+static SubPreviewData *
+sub_preview_data_new (const Babl          *format,
+                      GeglBuffer          *buffer,
+                      const GeglRectangle *rect,
+                      gdouble              scale)
+{
+  SubPreviewData *data = g_slice_new (SubPreviewData);
+
+  data->format = format;
+  data->buffer = g_object_ref (buffer);
+  data->rect   = *rect;
+  data->scale  = scale;
+
+  data->iter   = NULL;
+
+  return data;
+}
+
+static void
+sub_preview_data_free (SubPreviewData *data)
+{
+  g_object_unref (data->buffer);
+
+  if (data->iter)
+    gimp_chunk_iterator_stop (data->iter, TRUE);
+
+  g_slice_free (SubPreviewData, data);
+}
+
+
+/*  public functions  */
+
+
+GimpTempBuf *
+gimp_drawable_get_new_preview (GimpViewable *viewable,
+                               GimpContext  *context,
+                               gint          width,
+                               gint          height)
+{
+  GimpItem  *item  = GIMP_ITEM (viewable);
+  GimpImage *image = gimp_item_get_image (item);
+
+  if (! image->gimp->config->layer_previews)
+    return NULL;
+
+  return gimp_drawable_get_sub_preview (GIMP_DRAWABLE (viewable),
+                                        0, 0,
+                                        gimp_item_get_width  (item),
+                                        gimp_item_get_height (item),
+                                        width,
+                                        height);
+}
+
+GdkPixbuf *
+gimp_drawable_get_new_pixbuf (GimpViewable *viewable,
+                              GimpContext  *context,
+                              gint          width,
+                              gint          height)
+{
+  GimpItem  *item  = GIMP_ITEM (viewable);
+  GimpImage *image = gimp_item_get_image (item);
+
+  if (! image->gimp->config->layer_previews)
+    return NULL;
+
+  return gimp_drawable_get_sub_pixbuf (GIMP_DRAWABLE (viewable),
+                                       0, 0,
+                                       gimp_item_get_width  (item),
+                                       gimp_item_get_height (item),
+                                       width,
+                                       height);
+}
+
+const Babl *
+gimp_drawable_get_preview_format (GimpDrawable *drawable)
+{
+  gboolean alpha;
+  gboolean linear;
+
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
+
+  alpha  = gimp_drawable_has_alpha (drawable);
+  linear = gimp_drawable_get_linear (drawable);
+
+  switch (gimp_drawable_get_base_type (drawable))
+    {
+    case GIMP_GRAY:
+      return gimp_babl_format (GIMP_GRAY,
+                               gimp_babl_precision (GIMP_COMPONENT_TYPE_U8,
+                                                    linear),
+                               alpha);
+
+    case GIMP_RGB:
+      return gimp_babl_format (GIMP_RGB,
+                               gimp_babl_precision (GIMP_COMPONENT_TYPE_U8,
+                                                    linear),
+                               alpha);
+
+    case GIMP_INDEXED:
+      if (alpha)
+        return babl_format ("R'G'B'A u8");
+      else
+        return babl_format ("R'G'B' u8");
+    }
+
+  g_return_val_if_reached (NULL);
+}
+
+GimpTempBuf *
+gimp_drawable_get_sub_preview (GimpDrawable *drawable,
+                               gint          src_x,
+                               gint          src_y,
+                               gint          src_width,
+                               gint          src_height,
+                               gint          dest_width,
+                               gint          dest_height)
+{
+  GimpItem    *item;
+  GimpImage   *image;
+  GeglBuffer  *buffer;
+  GimpTempBuf *preview;
+  gdouble      scale;
+  gint         scaled_x;
+  gint         scaled_y;
+
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
+  g_return_val_if_fail (src_x >= 0, NULL);
+  g_return_val_if_fail (src_y >= 0, NULL);
+  g_return_val_if_fail (src_width  > 0, NULL);
+  g_return_val_if_fail (src_height > 0, NULL);
+  g_return_val_if_fail (dest_width  > 0, NULL);
+  g_return_val_if_fail (dest_height > 0, NULL);
+
+  item = GIMP_ITEM (drawable);
+
+  g_return_val_if_fail ((src_x + src_width)  <= gimp_item_get_width  (item), NULL);
+  g_return_val_if_fail ((src_y + src_height) <= gimp_item_get_height (item), NULL);
+
+  image = gimp_item_get_image (item);
+
+  if (! image->gimp->config->layer_previews)
+    return NULL;
+
+  buffer = gimp_drawable_get_buffer (drawable);
+
+  preview = gimp_temp_buf_new (dest_width, dest_height,
+                               gimp_drawable_get_preview_format (drawable));
+
+  scale = MIN ((gdouble) dest_width  / (gdouble) src_width,
+               (gdouble) dest_height / (gdouble) src_height);
+
+  scaled_x = RINT ((gdouble) src_x * scale);
+  scaled_y = RINT ((gdouble) src_y * scale);
+
+  gegl_buffer_get (buffer,
+                   GEGL_RECTANGLE (scaled_x, scaled_y, dest_width, dest_height),
+                   scale,
+                   gimp_temp_buf_get_format (preview),
+                   gimp_temp_buf_get_data (preview),
+                   GEGL_AUTO_ROWSTRIDE, GEGL_ABYSS_CLAMP);
+
+  return preview;
+}
+
+GdkPixbuf *
+gimp_drawable_get_sub_pixbuf (GimpDrawable *drawable,
+                              gint          src_x,
+                              gint          src_y,
+                              gint          src_width,
+                              gint          src_height,
+                              gint          dest_width,
+                              gint          dest_height)
+{
+  GimpItem           *item;
+  GimpImage          *image;
+  GeglBuffer         *buffer;
+  GdkPixbuf          *pixbuf;
+  gdouble             scale;
+  gint                scaled_x;
+  gint                scaled_y;
+  GimpColorTransform *transform;
+
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
+  g_return_val_if_fail (src_x >= 0, NULL);
+  g_return_val_if_fail (src_y >= 0, NULL);
+  g_return_val_if_fail (src_width  > 0, NULL);
+  g_return_val_if_fail (src_height > 0, NULL);
+  g_return_val_if_fail (dest_width  > 0, NULL);
+  g_return_val_if_fail (dest_height > 0, NULL);
+
+  item = GIMP_ITEM (drawable);
+
+  g_return_val_if_fail ((src_x + src_width)  <= gimp_item_get_width  (item), NULL);
+  g_return_val_if_fail ((src_y + src_height) <= gimp_item_get_height (item), NULL);
+
+  image = gimp_item_get_image (item);
+
+  if (! image->gimp->config->layer_previews)
+    return NULL;
+
+  buffer = gimp_drawable_get_buffer (drawable);
+
+  pixbuf = gdk_pixbuf_new (GDK_COLORSPACE_RGB, TRUE, 8,
+                           dest_width, dest_height);
+
+  scale = MIN ((gdouble) dest_width  / (gdouble) src_width,
+               (gdouble) dest_height / (gdouble) src_height);
+
+  scaled_x = RINT ((gdouble) src_x * scale);
+  scaled_y = RINT ((gdouble) src_y * scale);
+
+  transform = gimp_image_get_color_transform_to_srgb_u8 (image);
+
+  if (transform)
+    {
+      GimpTempBuf *temp_buf;
+      GeglBuffer  *src_buf;
+      GeglBuffer  *dest_buf;
+
+      temp_buf = gimp_temp_buf_new (dest_width, dest_height,
+                                    gimp_drawable_get_format (drawable));
+
+      gegl_buffer_get (buffer,
+                       GEGL_RECTANGLE (scaled_x, scaled_y,
+                                       dest_width, dest_height),
+                       scale,
+                       gimp_temp_buf_get_format (temp_buf),
+                       gimp_temp_buf_get_data (temp_buf),
+                       GEGL_AUTO_ROWSTRIDE, GEGL_ABYSS_CLAMP);
+
+      src_buf  = gimp_temp_buf_create_buffer (temp_buf);
+      dest_buf = gimp_pixbuf_create_buffer (pixbuf);
+
+      gimp_temp_buf_unref (temp_buf);
+
+      gimp_color_transform_process_buffer (transform,
+                                           src_buf,
+                                           GEGL_RECTANGLE (0, 0,
+                                                           dest_width, dest_height),
+                                           dest_buf,
+                                           GEGL_RECTANGLE (0, 0, 0, 0));
+
+      g_object_unref (src_buf);
+      g_object_unref (dest_buf);
+    }
+  else
+    {
+      gegl_buffer_get (buffer,
+                       GEGL_RECTANGLE (scaled_x, scaled_y,
+                                       dest_width, dest_height),
+                       scale,
+                       gimp_pixbuf_get_format (pixbuf),
+                       gdk_pixbuf_get_pixels (pixbuf),
+                       gdk_pixbuf_get_rowstride (pixbuf),
+                       GEGL_ABYSS_CLAMP);
+    }
+
+  return pixbuf;
+}
+
+static void
+gimp_drawable_get_sub_preview_async_func (GimpAsync      *async,
+                                          SubPreviewData *data)
+{
+  GimpTempBuf             *preview;
+  GimpTileHandlerValidate *validate;
+
+  preview = gimp_temp_buf_new (data->rect.width, data->rect.height,
+                               data->format);
+
+  validate = gimp_tile_handler_validate_get_assigned (data->buffer);
+
+  if (validate)
+    {
+      if (! data->iter)
+        {
+          cairo_region_t        *region;
+          cairo_rectangle_int_t  rect;
+
+          rect.x      = floor (data->rect.x / data->scale);
+          rect.y      = floor (data->rect.y / data->scale);
+          rect.width  = ceil ((data->rect.x + data->rect.width)  /
+                              data->scale) - rect.x;
+          rect.height = ceil ((data->rect.x + data->rect.height) /
+                              data->scale) - rect.y;
+
+          region = cairo_region_copy (validate->dirty_region);
+
+          cairo_region_intersect_rectangle (region, &rect);
+
+          data->iter = gimp_chunk_iterator_new (region);
+        }
+
+      if (gimp_chunk_iterator_next (data->iter))
+        {
+          GeglRectangle rect;
+
+          gimp_tile_handler_validate_begin_validate (validate);
+
+          while (gimp_chunk_iterator_get_rect (data->iter, &rect))
+            {
+              gimp_tile_handler_validate_validate (validate,
+                                                   data->buffer, &rect,
+                                                   FALSE, FALSE);
+            }
+
+          gimp_tile_handler_validate_end_validate (validate);
+
+          return;
+        }
+
+      data->iter = NULL;
+    }
+
+  gegl_buffer_get (data->buffer, &data->rect, data->scale,
+                   gimp_temp_buf_get_format (preview),
+                   gimp_temp_buf_get_data (preview),
+                   GEGL_AUTO_ROWSTRIDE, GEGL_ABYSS_CLAMP);
+
+  sub_preview_data_free (data);
+
+  gimp_async_finish_full (async,
+                          preview,
+                          (GDestroyNotify) gimp_temp_buf_unref);
+}
+
+GimpAsync *
+gimp_drawable_get_sub_preview_async (GimpDrawable *drawable,
+                                     gint          src_x,
+                                     gint          src_y,
+                                     gint          src_width,
+                                     gint          src_height,
+                                     gint          dest_width,
+                                     gint          dest_height)
+{
+  GimpItem       *item;
+  GimpImage      *image;
+  GeglBuffer     *buffer;
+  SubPreviewData *data;
+  gdouble         scale;
+  gint            scaled_x;
+  gint            scaled_y;
+  static gint     no_async_drawable_previews = -1;
+
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
+  g_return_val_if_fail (src_x >= 0, NULL);
+  g_return_val_if_fail (src_y >= 0, NULL);
+  g_return_val_if_fail (src_width  > 0, NULL);
+  g_return_val_if_fail (src_height > 0, NULL);
+  g_return_val_if_fail (dest_width  > 0, NULL);
+  g_return_val_if_fail (dest_height > 0, NULL);
+
+  item = GIMP_ITEM (drawable);
+
+  g_return_val_if_fail ((src_x + src_width)  <= gimp_item_get_width  (item), NULL);
+  g_return_val_if_fail ((src_y + src_height) <= gimp_item_get_height (item), NULL);
+
+  image = gimp_item_get_image (item);
+
+  if (! image->gimp->config->layer_previews)
+    return NULL;
+
+  buffer = gimp_drawable_get_buffer (drawable);
+
+  if (no_async_drawable_previews < 0)
+    {
+      no_async_drawable_previews =
+        (g_getenv ("GIMP_NO_ASYNC_DRAWABLE_PREVIEWS") != NULL);
+    }
+
+  if (no_async_drawable_previews)
+    {
+      GimpAsync *async = gimp_async_new ();
+
+      gimp_async_finish_full (async,
+                              gimp_drawable_get_sub_preview (drawable,
+                                                             src_x,
+                                                             src_y,
+                                                             src_width,
+                                                             src_height,
+                                                             dest_width,
+                                                             dest_height),
+                              (GDestroyNotify) gimp_temp_buf_unref);
+
+      return async;
+    }
+
+  scale = MIN ((gdouble) dest_width  / (gdouble) src_width,
+               (gdouble) dest_height / (gdouble) src_height);
+
+  scaled_x = RINT ((gdouble) src_x * scale);
+  scaled_y = RINT ((gdouble) src_y * scale);
+
+  data = sub_preview_data_new (
+    gimp_drawable_get_preview_format (drawable),
+    buffer,
+    GEGL_RECTANGLE (scaled_x, scaled_y, dest_width, dest_height),
+    scale);
+
+  if (gimp_tile_handler_validate_get_assigned (buffer))
+    {
+      return gimp_idle_run_async_full (
+        GIMP_PRIORITY_VIEWABLE_IDLE,
+        (GimpRunAsyncFunc) gimp_drawable_get_sub_preview_async_func,
+        data,
+        (GDestroyNotify) sub_preview_data_free);
+    }
+  else
+    {
+      return gimp_parallel_run_async_full (
+        +1,
+        (GimpRunAsyncFunc) gimp_drawable_get_sub_preview_async_func,
+        data,
+        (GDestroyNotify) sub_preview_data_free);
+    }
+}
diff --git a/app/core/gimpdrawable-preview.h b/app/core/gimpdrawable-preview.h
new file mode 100644
index 0000000..31f8ade
--- /dev/null
+++ b/app/core/gimpdrawable-preview.h
@@ -0,0 +1,63 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_DRAWABLE__PREVIEW_H__
+#define __GIMP_DRAWABLE__PREVIEW_H__
+
+
+/*
+ *  virtual functions of GimpDrawable -- don't call directly
+ */
+GimpTempBuf * gimp_drawable_get_new_preview       (GimpViewable *viewable,
+                                                   GimpContext  *context,
+                                                   gint          width,
+                                                   gint          height);
+GdkPixbuf   * gimp_drawable_get_new_pixbuf        (GimpViewable *viewable,
+                                                   GimpContext  *context,
+                                                   gint          width,
+                                                   gint          height);
+
+/*
+ *  normal functions (no virtuals)
+ */
+const Babl  * gimp_drawable_get_preview_format    (GimpDrawable *drawable);
+
+GimpTempBuf * gimp_drawable_get_sub_preview       (GimpDrawable *drawable,
+                                                   gint          src_x,
+                                                   gint          src_y,
+                                                   gint          src_width,
+                                                   gint          src_height,
+                                                   gint          dest_width,
+                                                   gint          dest_height);
+GdkPixbuf   * gimp_drawable_get_sub_pixbuf        (GimpDrawable *drawable,
+                                                   gint          src_x,
+                                                   gint          src_y,
+                                                   gint          src_width,
+                                                   gint          src_height,
+                                                   gint          dest_width,
+                                                   gint          dest_height);
+
+GimpAsync   * gimp_drawable_get_sub_preview_async (GimpDrawable *drawable,
+                                                   gint          src_x,
+                                                   gint          src_y,
+                                                   gint          src_width,
+                                                   gint          src_height,
+                                                   gint          dest_width,
+                                                   gint          dest_height);
+
+
+#endif /* __GIMP_DRAWABLE__PREVIEW_H__ */
diff --git a/app/core/gimpdrawable-private.h b/app/core/gimpdrawable-private.h
new file mode 100644
index 0000000..780d5bf
--- /dev/null
+++ b/app/core/gimpdrawable-private.h
@@ -0,0 +1,44 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_DRAWABLE_PRIVATE_H__
+#define __GIMP_DRAWABLE_PRIVATE_H__
+
+struct _GimpDrawablePrivate
+{
+  GeglBuffer     *buffer; /* buffer for drawable data */
+  GeglBuffer     *shadow; /* shadow buffer            */
+
+  GeglNode       *source_node;
+  GeglNode       *buffer_source_node;
+  GimpContainer  *filter_stack;
+  GeglRectangle   bounding_box;
+
+  GimpLayer      *floating_selection;
+  GimpFilter     *fs_filter;
+  GeglNode       *fs_crop_node;
+  GimpApplicator *fs_applicator;
+
+  GeglNode       *mode_node;
+
+  gint            paint_count;
+  GeglBuffer     *paint_buffer;
+  cairo_region_t *paint_copy_region;
+  cairo_region_t *paint_update_region;
+};
+
+#endif /* __GIMP_DRAWABLE_PRIVATE_H__ */
diff --git a/app/core/gimpdrawable-shadow.c b/app/core/gimpdrawable-shadow.c
new file mode 100644
index 0000000..4c42655
--- /dev/null
+++ b/app/core/gimpdrawable-shadow.c
@@ -0,0 +1,110 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+#include <cairo.h>
+
+#include "core-types.h"
+
+#include "gegl/gimp-gegl-utils.h"
+
+#include "gimpdrawable.h"
+#include "gimpdrawable-private.h"
+#include "gimpdrawable-shadow.h"
+
+
+GeglBuffer *
+gimp_drawable_get_shadow_buffer (GimpDrawable *drawable)
+{
+  GimpItem   *item;
+  gint        width;
+  gint        height;
+  const Babl *format;
+
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
+
+  item = GIMP_ITEM (drawable);
+
+  width  = gimp_item_get_width  (item);
+  height = gimp_item_get_height (item);
+  format = gimp_drawable_get_format (drawable);
+
+  if (drawable->private->shadow)
+    {
+      if ((width  != gegl_buffer_get_width  (drawable->private->shadow)) ||
+          (height != gegl_buffer_get_height (drawable->private->shadow)) ||
+          (format != gegl_buffer_get_format (drawable->private->shadow)))
+        {
+          gimp_drawable_free_shadow_buffer (drawable);
+        }
+      else
+        {
+          return drawable->private->shadow;
+        }
+    }
+
+  drawable->private->shadow = gegl_buffer_new (GEGL_RECTANGLE (0, 0,
+                                                               width, height),
+                                               format);
+
+  return drawable->private->shadow;
+}
+
+void
+gimp_drawable_free_shadow_buffer (GimpDrawable *drawable)
+{
+  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
+
+  g_clear_object (&drawable->private->shadow);
+}
+
+void
+gimp_drawable_merge_shadow_buffer (GimpDrawable *drawable,
+                                   gboolean      push_undo,
+                                   const gchar  *undo_desc)
+{
+  gint x, y;
+  gint width, height;
+
+  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
+  g_return_if_fail (gimp_item_is_attached (GIMP_ITEM (drawable)));
+  g_return_if_fail (GEGL_IS_BUFFER (drawable->private->shadow));
+
+  /*  A useful optimization here is to limit the update to the
+   *  extents of the selection mask, as it cannot extend beyond
+   *  them.
+   */
+  if (gimp_item_mask_intersect (GIMP_ITEM (drawable), &x, &y, &width, &height))
+    {
+      GeglBuffer *buffer = g_object_ref (drawable->private->shadow);
+
+      gimp_drawable_apply_buffer (drawable, buffer,
+                                  GEGL_RECTANGLE (x, y, width, height),
+                                  push_undo, undo_desc,
+                                  GIMP_OPACITY_OPAQUE,
+                                  GIMP_LAYER_MODE_REPLACE,
+                                  GIMP_LAYER_COLOR_SPACE_AUTO,
+                                  GIMP_LAYER_COLOR_SPACE_AUTO,
+                                  GIMP_LAYER_COMPOSITE_AUTO,
+                                  NULL, x, y);
+
+      g_object_unref (buffer);
+    }
+}
diff --git a/app/core/gimpdrawable-shadow.h b/app/core/gimpdrawable-shadow.h
new file mode 100644
index 0000000..b3ab582
--- /dev/null
+++ b/app/core/gimpdrawable-shadow.h
@@ -0,0 +1,32 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpdrawable-shadow.h
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_DRAWABLE_SHADOW_H__
+#define __GIMP_DRAWABLE_SHADOW_H__
+
+
+GeglBuffer * gimp_drawable_get_shadow_buffer   (GimpDrawable *drawable);
+void         gimp_drawable_free_shadow_buffer  (GimpDrawable *drawable);
+
+void         gimp_drawable_merge_shadow_buffer (GimpDrawable *drawable,
+                                                gboolean      push_undo,
+                                                const gchar  *undo_desc);
+
+
+#endif /* __GIMP_DRAWABLE_SHADOW_H__ */
diff --git a/app/core/gimpdrawable-stroke.c b/app/core/gimpdrawable-stroke.c
new file mode 100644
index 0000000..5b35d51
--- /dev/null
+++ b/app/core/gimpdrawable-stroke.c
@@ -0,0 +1,161 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpdrawable-stroke.c
+ * Copyright (C) 2003 Simon Budig  <simon@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <cairo.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+
+#include "core-types.h"
+
+#include "gimpchannel.h"
+#include "gimpdrawable-fill.h"
+#include "gimpdrawable-stroke.h"
+#include "gimperror.h"
+#include "gimpimage.h"
+#include "gimpscanconvert.h"
+#include "gimpstrokeoptions.h"
+
+#include "vectors/gimpvectors.h"
+
+#include "gimp-intl.h"
+
+
+/*  public functions  */
+
+void
+gimp_drawable_stroke_boundary (GimpDrawable       *drawable,
+                               GimpStrokeOptions  *options,
+                               const GimpBoundSeg *bound_segs,
+                               gint                n_bound_segs,
+                               gint                offset_x,
+                               gint                offset_y,
+                               gboolean            push_undo)
+{
+  GimpScanConvert *scan_convert;
+
+  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
+  g_return_if_fail (gimp_item_is_attached (GIMP_ITEM (drawable)));
+  g_return_if_fail (GIMP_IS_STROKE_OPTIONS (options));
+  g_return_if_fail (bound_segs == NULL || n_bound_segs != 0);
+  g_return_if_fail (gimp_fill_options_get_style (GIMP_FILL_OPTIONS (options)) !=
+                    GIMP_FILL_STYLE_PATTERN ||
+                    gimp_context_get_pattern (GIMP_CONTEXT (options)) != NULL);
+
+  scan_convert = gimp_scan_convert_new_from_boundary (bound_segs, n_bound_segs,
+                                                      offset_x, offset_y);
+
+  if (scan_convert)
+    {
+      gimp_drawable_stroke_scan_convert (drawable, options,
+                                         scan_convert, push_undo);
+      gimp_scan_convert_free (scan_convert);
+    }
+}
+
+gboolean
+gimp_drawable_stroke_vectors (GimpDrawable       *drawable,
+                              GimpStrokeOptions  *options,
+                              GimpVectors        *vectors,
+                              gboolean            push_undo,
+                              GError            **error)
+{
+  const GimpBezierDesc *bezier;
+
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), FALSE);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (drawable)), FALSE);
+  g_return_val_if_fail (GIMP_IS_STROKE_OPTIONS (options), FALSE);
+  g_return_val_if_fail (GIMP_IS_VECTORS (vectors), FALSE);
+  g_return_val_if_fail (gimp_fill_options_get_style (GIMP_FILL_OPTIONS (options)) !=
+                        GIMP_FILL_STYLE_PATTERN ||
+                        gimp_context_get_pattern (GIMP_CONTEXT (options)) != NULL,
+                        FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  bezier = gimp_vectors_get_bezier (vectors);
+
+  if (bezier && bezier->num_data >= 2)
+    {
+      GimpScanConvert *scan_convert = gimp_scan_convert_new ();
+
+      gimp_scan_convert_add_bezier (scan_convert, bezier);
+      gimp_drawable_stroke_scan_convert (drawable, options,
+                                         scan_convert, push_undo);
+
+      gimp_scan_convert_free (scan_convert);
+
+      return TRUE;
+    }
+
+  g_set_error_literal (error, GIMP_ERROR, GIMP_FAILED,
+                       _("Not enough points to stroke"));
+
+  return FALSE;
+}
+
+void
+gimp_drawable_stroke_scan_convert (GimpDrawable      *drawable,
+                                   GimpStrokeOptions *options,
+                                   GimpScanConvert   *scan_convert,
+                                   gboolean           push_undo)
+{
+  gdouble  width;
+  GimpUnit unit;
+
+  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
+  g_return_if_fail (gimp_item_is_attached (GIMP_ITEM (drawable)));
+  g_return_if_fail (GIMP_IS_STROKE_OPTIONS (options));
+  g_return_if_fail (scan_convert != NULL);
+  g_return_if_fail (gimp_fill_options_get_style (GIMP_FILL_OPTIONS (options)) !=
+                    GIMP_FILL_STYLE_PATTERN ||
+                    gimp_context_get_pattern (GIMP_CONTEXT (options)) != NULL);
+
+  if (! gimp_item_mask_intersect (GIMP_ITEM (drawable), NULL, NULL, NULL, NULL))
+    return;
+
+  width = gimp_stroke_options_get_width (options);
+  unit  = gimp_stroke_options_get_unit (options);
+
+  if (unit != GIMP_UNIT_PIXEL)
+    {
+      GimpImage *image = gimp_item_get_image (GIMP_ITEM (drawable));
+      gdouble    xres;
+      gdouble    yres;
+
+      gimp_image_get_resolution (image, &xres, &yres);
+
+      gimp_scan_convert_set_pixel_ratio (scan_convert, yres / xres);
+
+      width = gimp_units_to_pixels (width, unit, yres);
+    }
+
+  gimp_scan_convert_stroke (scan_convert, width,
+                            gimp_stroke_options_get_join_style (options),
+                            gimp_stroke_options_get_cap_style (options),
+                            gimp_stroke_options_get_miter_limit (options),
+                            gimp_stroke_options_get_dash_offset (options),
+                            gimp_stroke_options_get_dash_info (options));
+
+  gimp_drawable_fill_scan_convert (drawable, GIMP_FILL_OPTIONS (options),
+                                   scan_convert, push_undo);
+}
diff --git a/app/core/gimpdrawable-stroke.h b/app/core/gimpdrawable-stroke.h
new file mode 100644
index 0000000..5f16e5b
--- /dev/null
+++ b/app/core/gimpdrawable-stroke.h
@@ -0,0 +1,45 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpdrawable-stroke.h
+ * Copyright (C) 2003 Simon Budig  <simon@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef  __GIMP_DRAWABLE_STROKE_H__
+#define  __GIMP_DRAWABLE_STROKE_H__
+
+
+void       gimp_drawable_stroke_boundary     (GimpDrawable       *drawable,
+                                              GimpStrokeOptions  *options,
+                                              const GimpBoundSeg *bound_segs,
+                                              gint                n_bound_segs,
+                                              gint                offset_x,
+                                              gint                offset_y,
+                                              gboolean            push_undo);
+
+gboolean   gimp_drawable_stroke_vectors      (GimpDrawable       *drawable,
+                                              GimpStrokeOptions  *options,
+                                              GimpVectors        *vectors,
+                                              gboolean            push_undo,
+                                              GError            **error);
+
+void       gimp_drawable_stroke_scan_convert (GimpDrawable      *drawable,
+                                              GimpStrokeOptions *options,
+                                              GimpScanConvert   *scan_convert,
+                                              gboolean           push_undo);
+
+
+#endif  /*  __GIMP_DRAWABLE_STROKE_H__  */
diff --git a/app/core/gimpdrawable-transform.c b/app/core/gimpdrawable-transform.c
new file mode 100644
index 0000000..9cbedfd
--- /dev/null
+++ b/app/core/gimpdrawable-transform.c
@@ -0,0 +1,1070 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-2003 Spencer Kimball, Peter Mattis, and others
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+#include <cairo.h>
+#include <gegl.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpcolor/gimpcolor.h"
+#include "libgimpmath/gimpmath.h"
+
+#include "core-types.h"
+
+#include "gegl/gimp-gegl-apply-operation.h"
+#include "gegl/gimp-gegl-utils.h"
+
+#include "gimp.h"
+#include "gimp-transform-resize.h"
+#include "gimpchannel.h"
+#include "gimpcontext.h"
+#include "gimpdrawable-transform.h"
+#include "gimpimage.h"
+#include "gimpimage-undo.h"
+#include "gimpimage-undo-push.h"
+#include "gimplayer.h"
+#include "gimplayer-floating-selection.h"
+#include "gimplayer-new.h"
+#include "gimppickable.h"
+#include "gimpprogress.h"
+#include "gimpselection.h"
+
+#include "gimp-intl.h"
+
+
+#if defined (HAVE_FINITE)
+#define FINITE(x) finite(x)
+#elif defined (HAVE_ISFINITE)
+#define FINITE(x) isfinite(x)
+#elif defined (G_OS_WIN32)
+#define FINITE(x) _finite(x)
+#else
+#error "no FINITE() implementation available?!"
+#endif
+
+
+/*  public functions  */
+
+GeglBuffer *
+gimp_drawable_transform_buffer_affine (GimpDrawable            *drawable,
+                                       GimpContext             *context,
+                                       GeglBuffer              *orig_buffer,
+                                       gint                     orig_offset_x,
+                                       gint                     orig_offset_y,
+                                       const GimpMatrix3       *matrix,
+                                       GimpTransformDirection   direction,
+                                       GimpInterpolationType    interpolation_type,
+                                       GimpTransformResize      clip_result,
+                                       GimpColorProfile       **buffer_profile,
+                                       gint                    *new_offset_x,
+                                       gint                    *new_offset_y,
+                                       GimpProgress            *progress)
+{
+  GeglBuffer  *new_buffer;
+  GimpMatrix3  m;
+  gint         u1, v1, u2, v2;  /* source bounding box */
+  gint         x1, y1, x2, y2;  /* target bounding box */
+  GimpMatrix3  gegl_matrix;
+
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (drawable)), NULL);
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+  g_return_val_if_fail (GEGL_IS_BUFFER (orig_buffer), NULL);
+  g_return_val_if_fail (matrix != NULL, NULL);
+  g_return_val_if_fail (buffer_profile != NULL, NULL);
+  g_return_val_if_fail (new_offset_x != NULL, NULL);
+  g_return_val_if_fail (new_offset_y != NULL, NULL);
+  g_return_val_if_fail (progress == NULL || GIMP_IS_PROGRESS (progress), NULL);
+
+  *buffer_profile =
+    gimp_color_managed_get_color_profile (GIMP_COLOR_MANAGED (drawable));
+
+  m = *matrix;
+
+  if (direction == GIMP_TRANSFORM_BACKWARD)
+    {
+      /*  Find the inverse of the transformation matrix  */
+      gimp_matrix3_invert (&m);
+    }
+
+  u1 = orig_offset_x;
+  v1 = orig_offset_y;
+  u2 = u1 + gegl_buffer_get_width  (orig_buffer);
+  v2 = v1 + gegl_buffer_get_height (orig_buffer);
+
+  /*  Find the bounding coordinates of target */
+  gimp_transform_resize_boundary (&m, clip_result,
+                                  u1, v1, u2, v2,
+                                  &x1, &y1, &x2, &y2);
+
+  /*  Get the new temporary buffer for the transformed result  */
+  new_buffer = gegl_buffer_new (GEGL_RECTANGLE (0, 0, x2 - x1, y2 - y1),
+                                gegl_buffer_get_format (orig_buffer));
+
+  gimp_matrix3_identity (&gegl_matrix);
+  gimp_matrix3_translate (&gegl_matrix, u1, v1);
+  gimp_matrix3_mult (&m, &gegl_matrix);
+  gimp_matrix3_translate (&gegl_matrix, -x1, -y1);
+
+  gimp_gegl_apply_transform (orig_buffer, progress, NULL,
+                             new_buffer,
+                             interpolation_type,
+                             &gegl_matrix);
+
+  *new_offset_x = x1;
+  *new_offset_y = y1;
+
+  return new_buffer;
+}
+
+GeglBuffer *
+gimp_drawable_transform_buffer_flip (GimpDrawable         *drawable,
+                                     GimpContext          *context,
+                                     GeglBuffer           *orig_buffer,
+                                     gint                  orig_offset_x,
+                                     gint                  orig_offset_y,
+                                     GimpOrientationType   flip_type,
+                                     gdouble               axis,
+                                     gboolean              clip_result,
+                                     GimpColorProfile    **buffer_profile,
+                                     gint                 *new_offset_x,
+                                     gint                 *new_offset_y)
+{
+  const Babl         *format;
+  GeglBuffer         *new_buffer;
+  GeglBufferIterator *iter;
+  GeglRectangle       src_rect;
+  GeglRectangle       dest_rect;
+  gint                bpp;
+  gint                orig_x, orig_y;
+  gint                orig_width, orig_height;
+  gint                new_x, new_y;
+  gint                new_width, new_height;
+  gint                x, y;
+
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (drawable)), NULL);
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+  g_return_val_if_fail (GEGL_IS_BUFFER (orig_buffer), NULL);
+  g_return_val_if_fail (buffer_profile != NULL, NULL);
+  g_return_val_if_fail (new_offset_x != NULL, NULL);
+  g_return_val_if_fail (new_offset_y != NULL, NULL);
+
+  *buffer_profile =
+    gimp_color_managed_get_color_profile (GIMP_COLOR_MANAGED (drawable));
+
+  orig_x      = orig_offset_x;
+  orig_y      = orig_offset_y;
+  orig_width  = gegl_buffer_get_width (orig_buffer);
+  orig_height = gegl_buffer_get_height (orig_buffer);
+
+  new_x      = orig_x;
+  new_y      = orig_y;
+  new_width  = orig_width;
+  new_height = orig_height;
+
+  switch (flip_type)
+    {
+    case GIMP_ORIENTATION_HORIZONTAL:
+      new_x = RINT (-((gdouble) orig_x +
+                      (gdouble) orig_width - axis) + axis);
+      break;
+
+    case GIMP_ORIENTATION_VERTICAL:
+      new_y = RINT (-((gdouble) orig_y +
+                      (gdouble) orig_height - axis) + axis);
+      break;
+
+    case GIMP_ORIENTATION_UNKNOWN:
+      g_return_val_if_reached (NULL);
+      break;
+    }
+
+  format = gegl_buffer_get_format (orig_buffer);
+  bpp    = babl_format_get_bytes_per_pixel (format);
+
+  new_buffer = gegl_buffer_new (GEGL_RECTANGLE (0, 0,
+                                                new_width, new_height),
+                                format);
+
+  if (clip_result && (new_x != orig_x || new_y != orig_y))
+    {
+      GimpRGB    bg;
+      GeglColor *color;
+      gint       clip_x, clip_y;
+      gint       clip_width, clip_height;
+
+      *new_offset_x = orig_x;
+      *new_offset_y = orig_y;
+
+      /*  Use transparency, rather than the bg color, as the "outside" color of
+       *  channels, and drawables with an alpha channel.
+       */
+      if (GIMP_IS_CHANNEL (drawable) || babl_format_has_alpha (format))
+        {
+          gimp_rgba_set (&bg, 0.0, 0.0, 0.0, 0.0);
+        }
+      else
+        {
+          gimp_context_get_background (context, &bg);
+          gimp_pickable_srgb_to_image_color (GIMP_PICKABLE (drawable),
+                                             &bg, &bg);
+        }
+
+      color = gimp_gegl_color_new (&bg);
+      gegl_buffer_set_color (new_buffer, NULL, color);
+      g_object_unref (color);
+
+      if (gimp_rectangle_intersect (orig_x, orig_y, orig_width, orig_height,
+                                    new_x, new_y, new_width, new_height,
+                                    &clip_x, &clip_y,
+                                    &clip_width, &clip_height))
+        {
+          orig_x = new_x = clip_x - orig_x;
+          orig_y = new_y = clip_y - orig_y;
+        }
+
+      orig_width  = new_width  = clip_width;
+      orig_height = new_height = clip_height;
+    }
+  else
+    {
+      *new_offset_x = new_x;
+      *new_offset_y = new_y;
+
+      orig_x = 0;
+      orig_y = 0;
+      new_x  = 0;
+      new_y  = 0;
+    }
+
+  if (new_width == 0 && new_height == 0)
+    return new_buffer;
+
+  dest_rect.x      = new_x;
+  dest_rect.y      = new_y;
+  dest_rect.width  = new_width;
+  dest_rect.height = new_height;
+
+  iter = gegl_buffer_iterator_new (new_buffer, &dest_rect, 0, NULL,
+                                   GEGL_BUFFER_WRITE, GEGL_ABYSS_NONE, 1);
+
+  switch (flip_type)
+    {
+    case GIMP_ORIENTATION_HORIZONTAL:
+      while (gegl_buffer_iterator_next (iter))
+        {
+          gint stride = iter->items[0].roi.width * bpp;
+
+          src_rect = iter->items[0].roi;
+
+          src_rect.x = (orig_x + orig_width)          -
+                       (iter->items[0].roi.x - dest_rect.x) -
+                       iter->items[0].roi.width;
+
+          gegl_buffer_get (orig_buffer, &src_rect, 1.0, NULL, iter->items[0].data,
+                           stride, GEGL_ABYSS_NONE);
+
+          for (y = 0; y < iter->items[0].roi.height; y++)
+            {
+              guint8 *left  = iter->items[0].data;
+              guint8 *right = iter->items[0].data;
+
+              left  += y * stride;
+              right += y * stride + (iter->items[0].roi.width - 1) * bpp;
+
+              for (x = 0; x < iter->items[0].roi.width / 2; x++)
+                {
+                  guint8 temp[bpp];
+
+                  memcpy (temp,  left,  bpp);
+                  memcpy (left,  right, bpp);
+                  memcpy (right, temp,  bpp);
+
+                  left  += bpp;
+                  right -= bpp;
+                }
+            }
+        }
+      break;
+
+    case GIMP_ORIENTATION_VERTICAL:
+      while (gegl_buffer_iterator_next (iter))
+        {
+          gint stride = iter->items[0].roi.width * bpp;
+
+          src_rect = iter->items[0].roi;
+
+          src_rect.y = (orig_y + orig_height)         -
+                       (iter->items[0].roi.y - dest_rect.y) -
+                       iter->items[0].roi.height;
+
+          gegl_buffer_get (orig_buffer, &src_rect, 1.0, NULL, iter->items[0].data,
+                           stride, GEGL_ABYSS_NONE);
+
+          for (x = 0; x < iter->items[0].roi.width; x++)
+            {
+              guint8 *top    = iter->items[0].data;
+              guint8 *bottom = iter->items[0].data;
+
+              top    += x * bpp;
+              bottom += x * bpp + (iter->items[0].roi.height - 1) * stride;
+
+              for (y = 0; y < iter->items[0].roi.height / 2; y++)
+                {
+                  guint8 temp[bpp];
+
+                  memcpy (temp,   top,    bpp);
+                  memcpy (top,    bottom, bpp);
+                  memcpy (bottom, temp,   bpp);
+
+                  top    += stride;
+                  bottom -= stride;
+                }
+            }
+        }
+      break;
+
+    case GIMP_ORIENTATION_UNKNOWN:
+      gegl_buffer_iterator_stop (iter);
+      break;
+    }
+
+  return new_buffer;
+}
+
+static void
+gimp_drawable_transform_rotate_point (gint              x,
+                                      gint              y,
+                                      GimpRotationType  rotate_type,
+                                      gdouble           center_x,
+                                      gdouble           center_y,
+                                      gint             *new_x,
+                                      gint             *new_y)
+{
+  g_return_if_fail (new_x != NULL);
+  g_return_if_fail (new_y != NULL);
+
+  switch (rotate_type)
+    {
+    case GIMP_ROTATE_90:
+      *new_x = RINT (center_x - (gdouble) y + center_y);
+      *new_y = RINT (center_y + (gdouble) x - center_x);
+      break;
+
+    case GIMP_ROTATE_180:
+      *new_x = RINT (center_x - ((gdouble) x - center_x));
+      *new_y = RINT (center_y - ((gdouble) y - center_y));
+      break;
+
+    case GIMP_ROTATE_270:
+      *new_x = RINT (center_x + (gdouble) y - center_y);
+      *new_y = RINT (center_y - (gdouble) x + center_x);
+      break;
+
+    default:
+      *new_x = x;
+      *new_y = y;
+      g_return_if_reached ();
+    }
+}
+
+GeglBuffer *
+gimp_drawable_transform_buffer_rotate (GimpDrawable      *drawable,
+                                       GimpContext       *context,
+                                       GeglBuffer        *orig_buffer,
+                                       gint               orig_offset_x,
+                                       gint               orig_offset_y,
+                                       GimpRotationType   rotate_type,
+                                       gdouble            center_x,
+                                       gdouble            center_y,
+                                       gboolean           clip_result,
+                                       GimpColorProfile **buffer_profile,
+                                       gint              *new_offset_x,
+                                       gint              *new_offset_y)
+{
+  const Babl    *format;
+  GeglBuffer    *new_buffer;
+  GeglRectangle  src_rect;
+  GeglRectangle  dest_rect;
+  gint           orig_x, orig_y;
+  gint           orig_width, orig_height;
+  gint           orig_bpp;
+  gint           new_x, new_y;
+  gint           new_width, new_height;
+
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (drawable)), NULL);
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+  g_return_val_if_fail (GEGL_IS_BUFFER (orig_buffer), NULL);
+  g_return_val_if_fail (buffer_profile != NULL, NULL);
+  g_return_val_if_fail (new_offset_x != NULL, NULL);
+  g_return_val_if_fail (new_offset_y != NULL, NULL);
+
+  *buffer_profile =
+    gimp_color_managed_get_color_profile (GIMP_COLOR_MANAGED (drawable));
+
+  orig_x      = orig_offset_x;
+  orig_y      = orig_offset_y;
+  orig_width  = gegl_buffer_get_width (orig_buffer);
+  orig_height = gegl_buffer_get_height (orig_buffer);
+  orig_bpp    = babl_format_get_bytes_per_pixel (gegl_buffer_get_format (orig_buffer));
+
+  switch (rotate_type)
+    {
+    case GIMP_ROTATE_90:
+      gimp_drawable_transform_rotate_point (orig_x,
+                                            orig_y + orig_height,
+                                            rotate_type, center_x, center_y,
+                                            &new_x, &new_y);
+      new_width  = orig_height;
+      new_height = orig_width;
+      break;
+
+    case GIMP_ROTATE_180:
+      gimp_drawable_transform_rotate_point (orig_x + orig_width,
+                                            orig_y + orig_height,
+                                            rotate_type, center_x, center_y,
+                                            &new_x, &new_y);
+      new_width  = orig_width;
+      new_height = orig_height;
+      break;
+
+    case GIMP_ROTATE_270:
+      gimp_drawable_transform_rotate_point (orig_x + orig_width,
+                                            orig_y,
+                                            rotate_type, center_x, center_y,
+                                            &new_x, &new_y);
+      new_width  = orig_height;
+      new_height = orig_width;
+      break;
+
+    default:
+      g_return_val_if_reached (NULL);
+      break;
+    }
+
+  format = gegl_buffer_get_format (orig_buffer);
+
+  if (clip_result && (new_x != orig_x || new_y != orig_y ||
+                      new_width != orig_width || new_height != orig_height))
+
+    {
+      GimpRGB    bg;
+      GeglColor *color;
+      gint       clip_x, clip_y;
+      gint       clip_width, clip_height;
+
+      new_buffer = gegl_buffer_new (GEGL_RECTANGLE (0, 0,
+                                                    orig_width, orig_height),
+                                    format);
+
+      *new_offset_x = orig_x;
+      *new_offset_y = orig_y;
+
+      /*  Use transparency, rather than the bg color, as the "outside" color of
+       *  channels, and drawables with an alpha channel.
+       */
+      if (GIMP_IS_CHANNEL (drawable) || babl_format_has_alpha (format))
+        {
+          gimp_rgba_set (&bg, 0.0, 0.0, 0.0, 0.0);
+        }
+      else
+        {
+          gimp_context_get_background (context, &bg);
+          gimp_pickable_srgb_to_image_color (GIMP_PICKABLE (drawable),
+                                             &bg, &bg);
+        }
+
+      color = gimp_gegl_color_new (&bg);
+      gegl_buffer_set_color (new_buffer, NULL, color);
+      g_object_unref (color);
+
+      if (gimp_rectangle_intersect (orig_x, orig_y, orig_width, orig_height,
+                                    new_x, new_y, new_width, new_height,
+                                    &clip_x, &clip_y,
+                                    &clip_width, &clip_height))
+        {
+          gint saved_orig_x = orig_x;
+          gint saved_orig_y = orig_y;
+
+          new_x = clip_x - orig_x;
+          new_y = clip_y - orig_y;
+
+          switch (rotate_type)
+            {
+            case GIMP_ROTATE_90:
+              gimp_drawable_transform_rotate_point (clip_x + clip_width,
+                                                    clip_y,
+                                                    GIMP_ROTATE_270,
+                                                    center_x,
+                                                    center_y,
+                                                    &orig_x,
+                                                    &orig_y);
+              orig_x      -= saved_orig_x;
+              orig_y      -= saved_orig_y;
+              orig_width   = clip_height;
+              orig_height  = clip_width;
+              break;
+
+            case GIMP_ROTATE_180:
+              orig_x      = clip_x - orig_x;
+              orig_y      = clip_y - orig_y;
+              orig_width  = clip_width;
+              orig_height = clip_height;
+              break;
+
+            case GIMP_ROTATE_270:
+              gimp_drawable_transform_rotate_point (clip_x,
+                                                    clip_y + clip_height,
+                                                    GIMP_ROTATE_90,
+                                                    center_x,
+                                                    center_y,
+                                                    &orig_x,
+                                                    &orig_y);
+              orig_x      -= saved_orig_x;
+              orig_y      -= saved_orig_y;
+              orig_width   = clip_height;
+              orig_height  = clip_width;
+              break;
+            }
+
+          new_width  = clip_width;
+          new_height = clip_height;
+        }
+      else
+        {
+          new_width  = 0;
+          new_height = 0;
+        }
+    }
+  else
+    {
+      new_buffer = gegl_buffer_new (GEGL_RECTANGLE (0, 0,
+                                                    new_width, new_height),
+                                    format);
+
+      *new_offset_x = new_x;
+      *new_offset_y = new_y;
+
+      orig_x = 0;
+      orig_y = 0;
+      new_x  = 0;
+      new_y  = 0;
+    }
+
+  if (new_width < 1 || new_height < 1)
+    return new_buffer;
+
+  src_rect.x      = orig_x;
+  src_rect.y      = orig_y;
+  src_rect.width  = orig_width;
+  src_rect.height = orig_height;
+
+  dest_rect.x      = new_x;
+  dest_rect.y      = new_y;
+  dest_rect.width  = new_width;
+  dest_rect.height = new_height;
+
+  switch (rotate_type)
+    {
+    case GIMP_ROTATE_90:
+      {
+        guchar *buf = g_new (guchar, new_height * orig_bpp);
+        gint    i;
+
+        /* Not cool, we leak memory if we return, but anyway that is
+         * never supposed to happen. If we see this warning, a bug has
+         * to be fixed!
+         */
+        g_return_val_if_fail (new_height == orig_width, NULL);
+
+        src_rect.y      = orig_y + orig_height - 1;
+        src_rect.height = 1;
+
+        dest_rect.x     = new_x;
+        dest_rect.width = 1;
+
+        for (i = 0; i < orig_height; i++)
+          {
+            src_rect.y  = orig_y + orig_height - 1 - i;
+            dest_rect.x = new_x + i;
+
+            gegl_buffer_get (orig_buffer, &src_rect, 1.0, NULL, buf,
+                             GEGL_AUTO_ROWSTRIDE, GEGL_ABYSS_NONE);
+            gegl_buffer_set (new_buffer, &dest_rect, 0, NULL, buf,
+                             GEGL_AUTO_ROWSTRIDE);
+          }
+
+        g_free (buf);
+      }
+      break;
+
+    case GIMP_ROTATE_180:
+      {
+        guchar *buf = g_new (guchar, new_width * orig_bpp);
+        gint    i, j, k;
+
+        /* Not cool, we leak memory if we return, but anyway that is
+         * never supposed to happen. If we see this warning, a bug has
+         * to be fixed!
+         */
+        g_return_val_if_fail (new_width == orig_width, NULL);
+
+        src_rect.y      = orig_y + orig_height - 1;
+        src_rect.height = 1;
+
+        dest_rect.y      = new_y;
+        dest_rect.height = 1;
+
+        for (i = 0; i < orig_height; i++)
+          {
+            src_rect.y  = orig_y + orig_height - 1 - i;
+            dest_rect.y = new_y + i;
+
+            gegl_buffer_get (orig_buffer, &src_rect, 1.0, NULL, buf,
+                             GEGL_AUTO_ROWSTRIDE, GEGL_ABYSS_NONE);
+
+            for (j = 0; j < orig_width / 2; j++)
+              {
+                guchar *left  = buf + j * orig_bpp;
+                guchar *right = buf + (orig_width - 1 - j) * orig_bpp;
+
+                for (k = 0; k < orig_bpp; k++)
+                  {
+                    guchar tmp = left[k];
+                    left[k]    = right[k];
+                    right[k]   = tmp;
+                  }
+              }
+
+            gegl_buffer_set (new_buffer, &dest_rect, 0, NULL, buf,
+                             GEGL_AUTO_ROWSTRIDE);
+          }
+
+        g_free (buf);
+      }
+      break;
+
+    case GIMP_ROTATE_270:
+      {
+        guchar *buf = g_new (guchar, new_width * orig_bpp);
+        gint    i;
+
+        /* Not cool, we leak memory if we return, but anyway that is
+         * never supposed to happen. If we see this warning, a bug has
+         * to be fixed!
+         */
+        g_return_val_if_fail (new_width == orig_height, NULL);
+
+        src_rect.x     = orig_x + orig_width - 1;
+        src_rect.width = 1;
+
+        dest_rect.y      = new_y;
+        dest_rect.height = 1;
+
+        for (i = 0; i < orig_width; i++)
+          {
+            src_rect.x  = orig_x + orig_width - 1 - i;
+            dest_rect.y = new_y + i;
+
+            gegl_buffer_get (orig_buffer, &src_rect, 1.0, NULL, buf,
+                             GEGL_AUTO_ROWSTRIDE, GEGL_ABYSS_NONE);
+            gegl_buffer_set (new_buffer, &dest_rect, 0, NULL, buf,
+                             GEGL_AUTO_ROWSTRIDE);
+          }
+
+        g_free (buf);
+      }
+      break;
+    }
+
+  return new_buffer;
+}
+
+GimpDrawable *
+gimp_drawable_transform_affine (GimpDrawable           *drawable,
+                                GimpContext            *context,
+                                const GimpMatrix3      *matrix,
+                                GimpTransformDirection  direction,
+                                GimpInterpolationType   interpolation_type,
+                                GimpTransformResize     clip_result,
+                                GimpProgress           *progress)
+{
+  GimpImage    *image;
+  GeglBuffer   *orig_buffer;
+  gint          orig_offset_x;
+  gint          orig_offset_y;
+  gboolean      new_layer;
+  GimpDrawable *result = NULL;
+
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (drawable)), NULL);
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+  g_return_val_if_fail (matrix != NULL, NULL);
+  g_return_val_if_fail (progress == NULL || GIMP_IS_PROGRESS (progress), NULL);
+
+  image = gimp_item_get_image (GIMP_ITEM (drawable));
+
+  /* Start a transform undo group */
+  gimp_image_undo_group_start (image,
+                               GIMP_UNDO_GROUP_TRANSFORM,
+                               C_("undo-type", "Transform"));
+
+  /* Cut/Copy from the specified drawable */
+  orig_buffer = gimp_drawable_transform_cut (drawable, context,
+                                             &orig_offset_x, &orig_offset_y,
+                                             &new_layer);
+
+  if (orig_buffer)
+    {
+      GeglBuffer       *new_buffer;
+      gint              new_offset_x;
+      gint              new_offset_y;
+      GimpColorProfile *profile;
+
+      /*  also transform the mask if we are transforming an entire layer  */
+      if (GIMP_IS_LAYER (drawable) &&
+          gimp_layer_get_mask (GIMP_LAYER (drawable)) &&
+          gimp_channel_is_empty (gimp_image_get_mask (image)))
+        {
+          GimpLayerMask *mask = gimp_layer_get_mask (GIMP_LAYER (drawable));
+
+          gimp_item_transform (GIMP_ITEM (mask), context,
+                               matrix,
+                               direction,
+                               interpolation_type,
+                               clip_result,
+                               progress);
+        }
+
+      /* transform the buffer */
+      new_buffer = gimp_drawable_transform_buffer_affine (drawable, context,
+                                                          orig_buffer,
+                                                          orig_offset_x,
+                                                          orig_offset_y,
+                                                          matrix,
+                                                          direction,
+                                                          interpolation_type,
+                                                          clip_result,
+                                                          &profile,
+                                                          &new_offset_x,
+                                                          &new_offset_y,
+                                                          progress);
+
+      /* Free the cut/copied buffer */
+      g_object_unref (orig_buffer);
+
+      if (new_buffer)
+        {
+          result = gimp_drawable_transform_paste (drawable, new_buffer, profile,
+                                                  new_offset_x, new_offset_y,
+                                                  new_layer);
+          g_object_unref (new_buffer);
+        }
+    }
+
+  /*  push the undo group end  */
+  gimp_image_undo_group_end (image);
+
+  return result;
+}
+
+GimpDrawable *
+gimp_drawable_transform_flip (GimpDrawable        *drawable,
+                              GimpContext         *context,
+                              GimpOrientationType  flip_type,
+                              gdouble              axis,
+                              gboolean             clip_result)
+{
+  GimpImage    *image;
+  GeglBuffer   *orig_buffer;
+  gint          orig_offset_x;
+  gint          orig_offset_y;
+  gboolean      new_layer;
+  GimpDrawable *result = NULL;
+
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (drawable)), NULL);
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+
+  image = gimp_item_get_image (GIMP_ITEM (drawable));
+
+  /* Start a transform undo group */
+  gimp_image_undo_group_start (image,
+                               GIMP_UNDO_GROUP_TRANSFORM,
+                               C_("undo-type", "Flip"));
+
+  /* Cut/Copy from the specified drawable */
+  orig_buffer = gimp_drawable_transform_cut (drawable, context,
+                                             &orig_offset_x, &orig_offset_y,
+                                             &new_layer);
+
+  if (orig_buffer)
+    {
+      GeglBuffer       *new_buffer;
+      gint              new_offset_x;
+      gint              new_offset_y;
+      GimpColorProfile *profile;
+
+      /*  also transform the mask if we are transforming an entire layer  */
+      if (GIMP_IS_LAYER (drawable) &&
+          gimp_layer_get_mask (GIMP_LAYER (drawable)) &&
+          gimp_channel_is_empty (gimp_image_get_mask (image)))
+        {
+          GimpLayerMask *mask = gimp_layer_get_mask (GIMP_LAYER (drawable));
+
+          gimp_item_flip (GIMP_ITEM (mask), context,
+                          flip_type,
+                          axis,
+                          clip_result);
+        }
+
+      /* transform the buffer */
+      new_buffer = gimp_drawable_transform_buffer_flip (drawable, context,
+                                                        orig_buffer,
+                                                        orig_offset_x,
+                                                        orig_offset_y,
+                                                        flip_type, axis,
+                                                        clip_result,
+                                                        &profile,
+                                                        &new_offset_x,
+                                                        &new_offset_y);
+
+      /* Free the cut/copied buffer */
+      g_object_unref (orig_buffer);
+
+      if (new_buffer)
+        {
+          result = gimp_drawable_transform_paste (drawable, new_buffer, profile,
+                                                  new_offset_x, new_offset_y,
+                                                  new_layer);
+          g_object_unref (new_buffer);
+        }
+    }
+
+  /*  push the undo group end  */
+  gimp_image_undo_group_end (image);
+
+  return result;
+}
+
+GimpDrawable *
+gimp_drawable_transform_rotate (GimpDrawable     *drawable,
+                                GimpContext      *context,
+                                GimpRotationType  rotate_type,
+                                gdouble           center_x,
+                                gdouble           center_y,
+                                gboolean          clip_result)
+{
+  GimpImage    *image;
+  GeglBuffer   *orig_buffer;
+  gint          orig_offset_x;
+  gint          orig_offset_y;
+  gboolean      new_layer;
+  GimpDrawable *result = NULL;
+
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (drawable)), NULL);
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+
+  image = gimp_item_get_image (GIMP_ITEM (drawable));
+
+  /* Start a transform undo group */
+  gimp_image_undo_group_start (image,
+                               GIMP_UNDO_GROUP_TRANSFORM,
+                               C_("undo-type", "Rotate"));
+
+  /* Cut/Copy from the specified drawable */
+  orig_buffer = gimp_drawable_transform_cut (drawable, context,
+                                             &orig_offset_x, &orig_offset_y,
+                                             &new_layer);
+
+  if (orig_buffer)
+    {
+      GeglBuffer       *new_buffer;
+      gint              new_offset_x;
+      gint              new_offset_y;
+      GimpColorProfile *profile;
+
+      /*  also transform the mask if we are transforming an entire layer  */
+      if (GIMP_IS_LAYER (drawable) &&
+          gimp_layer_get_mask (GIMP_LAYER (drawable)) &&
+          gimp_channel_is_empty (gimp_image_get_mask (image)))
+        {
+          GimpLayerMask *mask = gimp_layer_get_mask (GIMP_LAYER (drawable));
+
+          gimp_item_rotate (GIMP_ITEM (mask), context,
+                            rotate_type,
+                            center_x,
+                            center_y,
+                            clip_result);
+        }
+
+      /* transform the buffer */
+      new_buffer = gimp_drawable_transform_buffer_rotate (drawable, context,
+                                                          orig_buffer,
+                                                          orig_offset_x,
+                                                          orig_offset_y,
+                                                          rotate_type,
+                                                          center_x, center_y,
+                                                          clip_result,
+                                                          &profile,
+                                                          &new_offset_x,
+                                                          &new_offset_y);
+
+      /* Free the cut/copied buffer */
+      g_object_unref (orig_buffer);
+
+      if (new_buffer)
+        {
+          result = gimp_drawable_transform_paste (drawable, new_buffer, profile,
+                                                  new_offset_x, new_offset_y,
+                                                  new_layer);
+          g_object_unref (new_buffer);
+        }
+    }
+
+  /*  push the undo group end  */
+  gimp_image_undo_group_end (image);
+
+  return result;
+}
+
+GeglBuffer *
+gimp_drawable_transform_cut (GimpDrawable *drawable,
+                             GimpContext  *context,
+                             gint         *offset_x,
+                             gint         *offset_y,
+                             gboolean     *new_layer)
+{
+  GimpImage  *image;
+  GeglBuffer *buffer;
+
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (drawable)), NULL);
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+  g_return_val_if_fail (offset_x != NULL, NULL);
+  g_return_val_if_fail (offset_y != NULL, NULL);
+  g_return_val_if_fail (new_layer != NULL, NULL);
+
+  image = gimp_item_get_image (GIMP_ITEM (drawable));
+
+  /*  extract the selected mask if there is a selection  */
+  if (! gimp_channel_is_empty (gimp_image_get_mask (image)))
+    {
+      gint x, y, w, h;
+
+      /* set the keep_indexed flag to FALSE here, since we use
+       * gimp_layer_new_from_gegl_buffer() later which assumes that
+       * the buffer are either RGB or GRAY.  Eeek!!!  (Sven)
+       */
+      if (gimp_item_mask_intersect (GIMP_ITEM (drawable), &x, &y, &w, &h))
+        {
+          buffer = gimp_selection_extract (GIMP_SELECTION (gimp_image_get_mask (image)),
+                                           GIMP_PICKABLE (drawable),
+                                           context,
+                                           TRUE, FALSE, TRUE,
+                                           offset_x, offset_y,
+                                           NULL);
+          /*  clear the selection  */
+          gimp_channel_clear (gimp_image_get_mask (image), NULL, TRUE);
+
+          *new_layer = TRUE;
+        }
+      else
+        {
+          buffer = NULL;
+          *new_layer = FALSE;
+        }
+    }
+  else  /*  otherwise, just copy the layer  */
+    {
+      buffer = gimp_selection_extract (GIMP_SELECTION (gimp_image_get_mask (image)),
+                                       GIMP_PICKABLE (drawable),
+                                       context,
+                                       FALSE, TRUE, GIMP_IS_LAYER (drawable),
+                                       offset_x, offset_y,
+                                       NULL);
+
+      *new_layer = FALSE;
+    }
+
+  return buffer;
+}
+
+GimpDrawable *
+gimp_drawable_transform_paste (GimpDrawable     *drawable,
+                               GeglBuffer       *buffer,
+                               GimpColorProfile *buffer_profile,
+                               gint              offset_x,
+                               gint              offset_y,
+                               gboolean          new_layer)
+{
+  GimpImage   *image;
+  GimpLayer   *layer     = NULL;
+  const gchar *undo_desc = NULL;
+
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (drawable)), NULL);
+  g_return_val_if_fail (GEGL_IS_BUFFER (buffer), NULL);
+  g_return_val_if_fail (GIMP_IS_COLOR_PROFILE (buffer_profile), NULL);
+
+  image = gimp_item_get_image (GIMP_ITEM (drawable));
+
+  if (GIMP_IS_LAYER (drawable))
+    undo_desc = C_("undo-type", "Transform Layer");
+  else if (GIMP_IS_CHANNEL (drawable))
+    undo_desc = C_("undo-type", "Transform Channel");
+  else
+    return NULL;
+
+  gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_EDIT_PASTE, undo_desc);
+
+  if (new_layer)
+    {
+      layer =
+        gimp_layer_new_from_gegl_buffer (buffer, image,
+                                         gimp_drawable_get_format_with_alpha (drawable),
+                                         _("Transformation"),
+                                         GIMP_OPACITY_OPAQUE,
+                                         gimp_image_get_default_new_layer_mode (image),
+                                         buffer_profile);
+
+      gimp_item_set_offset (GIMP_ITEM (layer), offset_x, offset_y);
+
+      floating_sel_attach (layer, drawable);
+
+      drawable = GIMP_DRAWABLE (layer);
+    }
+  else
+    {
+      gimp_drawable_set_buffer_full (drawable, TRUE, NULL,
+                                     buffer,
+                                     GEGL_RECTANGLE (offset_x, offset_y, 0, 0),
+                                     TRUE);
+    }
+
+  gimp_image_undo_group_end (image);
+
+  return drawable;
+}
diff --git a/app/core/gimpdrawable-transform.h b/app/core/gimpdrawable-transform.h
new file mode 100644
index 0000000..8cdd53f
--- /dev/null
+++ b/app/core/gimpdrawable-transform.h
@@ -0,0 +1,94 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-2001 Spencer Kimball, Peter Mattis, and others
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_DRAWABLE_TRANSFORM_H__
+#define __GIMP_DRAWABLE_TRANSFORM_H__
+
+
+GeglBuffer          * gimp_drawable_transform_buffer_affine      (GimpDrawable            *drawable,
+                                                                  GimpContext             *context,
+                                                                  GeglBuffer              *orig_buffer,
+                                                                  gint                     orig_offset_x,
+                                                                  gint                     orig_offset_y,
+                                                                  const GimpMatrix3       *matrix,
+                                                                  GimpTransformDirection   direction,
+                                                                  GimpInterpolationType    interpolation_type,
+                                                                  GimpTransformResize      clip_result,
+                                                                  GimpColorProfile       **buffer_profile,
+                                                                  gint                    *new_offset_x,
+                                                                  gint                    *new_offset_y,
+                                                                  GimpProgress            *progress);
+GeglBuffer          * gimp_drawable_transform_buffer_flip        (GimpDrawable            *drawable,
+                                                                  GimpContext             *context,
+                                                                  GeglBuffer              *orig_buffer,
+                                                                  gint                     orig_offset_x,
+                                                                  gint                     orig_offset_y,
+                                                                  GimpOrientationType      flip_type,
+                                                                  gdouble                  axis,
+                                                                  gboolean                 clip_result,
+                                                                  GimpColorProfile       **buffer_profile,
+                                                                  gint                    *new_offset_x,
+                                                                  gint                    *new_offset_y);
+
+GeglBuffer          * gimp_drawable_transform_buffer_rotate      (GimpDrawable            *drawable,
+                                                                  GimpContext             *context,
+                                                                  GeglBuffer              *buffer,
+                                                                  gint                     orig_offset_x,
+                                                                  gint                     orig_offset_y,
+                                                                  GimpRotationType         rotate_type,
+                                                                  gdouble                  center_x,
+                                                                  gdouble                  center_y,
+                                                                  gboolean                 clip_result,
+                                                                  GimpColorProfile       **buffer_profile,
+                                                                  gint                    *new_offset_x,
+                                                                  gint                    *new_offset_y);
+
+GimpDrawable         * gimp_drawable_transform_affine            (GimpDrawable            *drawable,
+                                                                  GimpContext             *context,
+                                                                  const GimpMatrix3       *matrix,
+                                                                  GimpTransformDirection   direction,
+                                                                  GimpInterpolationType    interpolation_type,
+                                                                  GimpTransformResize      clip_result,
+                                                                  GimpProgress            *progress);
+
+GimpDrawable         * gimp_drawable_transform_flip              (GimpDrawable            *drawable,
+                                                                  GimpContext             *context,
+                                                                  GimpOrientationType      flip_type,
+                                                                  gdouble                  axis,
+                                                                  gboolean                 clip_result);
+
+GimpDrawable         * gimp_drawable_transform_rotate            (GimpDrawable            *drawable,
+                                                                  GimpContext             *context,
+                                                                  GimpRotationType         rotate_type,
+                                                                  gdouble                  center_x,
+                                                                  gdouble                  center_y,
+                                                                  gboolean                 clip_result);
+
+GeglBuffer           * gimp_drawable_transform_cut               (GimpDrawable            *drawable,
+                                                                  GimpContext             *context,
+                                                                  gint                    *offset_x,
+                                                                  gint                    *offset_y,
+                                                                  gboolean                *new_layer);
+GimpDrawable         * gimp_drawable_transform_paste             (GimpDrawable            *drawable,
+                                                                  GeglBuffer              *buffer,
+                                                                  GimpColorProfile        *buffer_profile,
+                                                                  gint                     offset_x,
+                                                                  gint                     offset_y,
+                                                                  gboolean                 new_layer);
+
+
+#endif  /*  __GIMP_DRAWABLE_TRANSFORM_H__  */
diff --git a/app/core/gimpdrawable.c b/app/core/gimpdrawable.c
new file mode 100644
index 0000000..9a85eee
--- /dev/null
+++ b/app/core/gimpdrawable.c
@@ -0,0 +1,1916 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <cairo.h>
+#include <gegl.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpcolor/gimpcolor.h"
+#include "libgimpmath/gimpmath.h"
+
+#include "core-types.h"
+
+#include "gegl/gimp-babl.h"
+#include "gegl/gimp-gegl-apply-operation.h"
+#include "gegl/gimp-gegl-loops.h"
+#include "gegl/gimp-gegl-utils.h"
+
+#include "gimp-memsize.h"
+#include "gimp-utils.h"
+#include "gimpchannel.h"
+#include "gimpcontext.h"
+#include "gimpdrawable-combine.h"
+#include "gimpdrawable-fill.h"
+#include "gimpdrawable-floating-selection.h"
+#include "gimpdrawable-preview.h"
+#include "gimpdrawable-private.h"
+#include "gimpdrawable-shadow.h"
+#include "gimpdrawable-transform.h"
+#include "gimpfilterstack.h"
+#include "gimpimage.h"
+#include "gimpimage-colormap.h"
+#include "gimpimage-undo-push.h"
+#include "gimpmarshal.h"
+#include "gimppickable.h"
+#include "gimpprogress.h"
+
+#include "gimp-log.h"
+
+#include "gimp-intl.h"
+
+
+#define PAINT_UPDATE_CHUNK_WIDTH  32
+#define PAINT_UPDATE_CHUNK_HEIGHT 32
+
+
+enum
+{
+  UPDATE,
+  FORMAT_CHANGED,
+  ALPHA_CHANGED,
+  BOUNDING_BOX_CHANGED,
+  LAST_SIGNAL
+};
+
+enum
+{
+  PROP_0,
+  PROP_BUFFER
+};
+
+
+/*  local function prototypes  */
+
+static void       gimp_color_managed_iface_init    (GimpColorManagedInterface *iface);
+static void       gimp_pickable_iface_init         (GimpPickableInterface     *iface);
+
+static void       gimp_drawable_dispose            (GObject           *object);
+static void       gimp_drawable_finalize           (GObject           *object);
+static void       gimp_drawable_set_property       (GObject           *object,
+                                                    guint              property_id,
+                                                    const GValue      *value,
+                                                    GParamSpec        *pspec);
+static void       gimp_drawable_get_property       (GObject           *object,
+                                                    guint              property_id,
+                                                    GValue            *value,
+                                                    GParamSpec        *pspec);
+
+static gint64     gimp_drawable_get_memsize        (GimpObject        *object,
+                                                    gint64            *gui_size);
+
+static gboolean   gimp_drawable_get_size           (GimpViewable      *viewable,
+                                                    gint              *width,
+                                                    gint              *height);
+static void       gimp_drawable_preview_freeze     (GimpViewable      *viewable);
+static void       gimp_drawable_preview_thaw       (GimpViewable      *viewable);
+
+static GeglNode * gimp_drawable_get_node           (GimpFilter        *filter);
+
+static void       gimp_drawable_removed            (GimpItem          *item);
+static GimpItem * gimp_drawable_duplicate          (GimpItem          *item,
+                                                    GType              new_type);
+static void       gimp_drawable_scale              (GimpItem          *item,
+                                                    gint               new_width,
+                                                    gint               new_height,
+                                                    gint               new_offset_x,
+                                                    gint               new_offset_y,
+                                                    GimpInterpolationType interp_type,
+                                                    GimpProgress      *progress);
+static void       gimp_drawable_resize             (GimpItem          *item,
+                                                    GimpContext       *context,
+                                                    GimpFillType       fill_type,
+                                                    gint               new_width,
+                                                    gint               new_height,
+                                                    gint               offset_x,
+                                                    gint               offset_y);
+static void       gimp_drawable_flip               (GimpItem          *item,
+                                                    GimpContext       *context,
+                                                    GimpOrientationType  flip_type,
+                                                    gdouble            axis,
+                                                    gboolean           clip_result);
+static void       gimp_drawable_rotate             (GimpItem          *item,
+                                                    GimpContext       *context,
+                                                    GimpRotationType   rotate_type,
+                                                    gdouble            center_x,
+                                                    gdouble            center_y,
+                                                    gboolean           clip_result);
+static void       gimp_drawable_transform          (GimpItem          *item,
+                                                    GimpContext       *context,
+                                                    const GimpMatrix3 *matrix,
+                                                    GimpTransformDirection direction,
+                                                    GimpInterpolationType interpolation_type,
+                                                    GimpTransformResize clip_result,
+                                                    GimpProgress      *progress);
+
+static const guint8 *
+                  gimp_drawable_get_icc_profile    (GimpColorManaged  *managed,
+                                                    gsize             *len);
+static GimpColorProfile *
+                  gimp_drawable_get_color_profile  (GimpColorManaged  *managed);
+static void       gimp_drawable_profile_changed    (GimpColorManaged  *managed);
+
+static gboolean   gimp_drawable_get_pixel_at       (GimpPickable      *pickable,
+                                                    gint               x,
+                                                    gint               y,
+                                                    const Babl        *format,
+                                                    gpointer           pixel);
+static void       gimp_drawable_get_pixel_average  (GimpPickable      *pickable,
+                                                    const GeglRectangle *rect,
+                                                    const Babl        *format,
+                                                    gpointer           pixel);
+
+static void       gimp_drawable_real_update        (GimpDrawable      *drawable,
+                                                    gint               x,
+                                                    gint               y,
+                                                    gint               width,
+                                                    gint               height);
+
+static gint64  gimp_drawable_real_estimate_memsize (GimpDrawable      *drawable,
+                                                    GimpComponentType  component_type,
+                                                    gint               width,
+                                                    gint               height);
+
+static void       gimp_drawable_real_update_all    (GimpDrawable      *drawable);
+
+static GimpComponentMask
+                gimp_drawable_real_get_active_mask (GimpDrawable      *drawable);
+
+static gboolean   gimp_drawable_real_supports_alpha
+                                                   (GimpDrawable     *drawable);
+
+static void       gimp_drawable_real_convert_type  (GimpDrawable      *drawable,
+                                                    GimpImage         *dest_image,
+                                                    const Babl        *new_format,
+                                                    GimpColorProfile  *dest_profile,
+                                                    GeglDitherMethod   layer_dither_type,
+                                                    GeglDitherMethod   mask_dither_type,
+                                                    gboolean           push_undo,
+                                                    GimpProgress      *progress);
+
+static GeglBuffer * gimp_drawable_real_get_buffer  (GimpDrawable      *drawable);
+static void       gimp_drawable_real_set_buffer    (GimpDrawable      *drawable,
+                                                    gboolean           push_undo,
+                                                    const gchar       *undo_desc,
+                                                    GeglBuffer        *buffer,
+                                                    const GeglRectangle *bounds);
+
+static GeglRectangle gimp_drawable_real_get_bounding_box
+                                                   (GimpDrawable      *drawable);
+
+static void       gimp_drawable_real_push_undo     (GimpDrawable      *drawable,
+                                                    const gchar       *undo_desc,
+                                                    GeglBuffer        *buffer,
+                                                    gint               x,
+                                                    gint               y,
+                                                    gint               width,
+                                                    gint               height);
+static void       gimp_drawable_real_swap_pixels   (GimpDrawable      *drawable,
+                                                    GeglBuffer        *buffer,
+                                                    gint               x,
+                                                    gint               y);
+static GeglNode * gimp_drawable_real_get_source_node (GimpDrawable    *drawable);
+
+static void       gimp_drawable_format_changed     (GimpDrawable      *drawable);
+static void       gimp_drawable_alpha_changed      (GimpDrawable      *drawable);
+
+
+G_DEFINE_TYPE_WITH_CODE (GimpDrawable, gimp_drawable, GIMP_TYPE_ITEM,
+                         G_ADD_PRIVATE (GimpDrawable)
+                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_COLOR_MANAGED,
+                                                gimp_color_managed_iface_init)
+                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_PICKABLE,
+                                                gimp_pickable_iface_init))
+
+#define parent_class gimp_drawable_parent_class
+
+static guint gimp_drawable_signals[LAST_SIGNAL] = { 0 };
+
+
+static void
+gimp_drawable_class_init (GimpDrawableClass *klass)
+{
+  GObjectClass      *object_class      = G_OBJECT_CLASS (klass);
+  GimpObjectClass   *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+  GimpViewableClass *viewable_class    = GIMP_VIEWABLE_CLASS (klass);
+  GimpFilterClass   *filter_class      = GIMP_FILTER_CLASS (klass);
+  GimpItemClass     *item_class        = GIMP_ITEM_CLASS (klass);
+
+  gimp_drawable_signals[UPDATE] =
+    g_signal_new ("update",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpDrawableClass, update),
+                  NULL, NULL,
+                  gimp_marshal_VOID__INT_INT_INT_INT,
+                  G_TYPE_NONE, 4,
+                  G_TYPE_INT,
+                  G_TYPE_INT,
+                  G_TYPE_INT,
+                  G_TYPE_INT);
+
+  gimp_drawable_signals[FORMAT_CHANGED] =
+    g_signal_new ("format-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpDrawableClass, format_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  gimp_drawable_signals[ALPHA_CHANGED] =
+    g_signal_new ("alpha-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpDrawableClass, alpha_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  gimp_drawable_signals[BOUNDING_BOX_CHANGED] =
+    g_signal_new ("bounding-box-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpDrawableClass, bounding_box_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  object_class->dispose           = gimp_drawable_dispose;
+  object_class->finalize          = gimp_drawable_finalize;
+  object_class->set_property      = gimp_drawable_set_property;
+  object_class->get_property      = gimp_drawable_get_property;
+
+  gimp_object_class->get_memsize  = gimp_drawable_get_memsize;
+
+  viewable_class->get_size        = gimp_drawable_get_size;
+  viewable_class->get_new_preview = gimp_drawable_get_new_preview;
+  viewable_class->get_new_pixbuf  = gimp_drawable_get_new_pixbuf;
+  viewable_class->preview_freeze  = gimp_drawable_preview_freeze;
+  viewable_class->preview_thaw    = gimp_drawable_preview_thaw;
+
+  filter_class->get_node          = gimp_drawable_get_node;
+
+  item_class->removed             = gimp_drawable_removed;
+  item_class->duplicate           = gimp_drawable_duplicate;
+  item_class->scale               = gimp_drawable_scale;
+  item_class->resize              = gimp_drawable_resize;
+  item_class->flip                = gimp_drawable_flip;
+  item_class->rotate              = gimp_drawable_rotate;
+  item_class->transform           = gimp_drawable_transform;
+
+  klass->update                   = gimp_drawable_real_update;
+  klass->format_changed           = NULL;
+  klass->alpha_changed            = NULL;
+  klass->bounding_box_changed     = NULL;
+  klass->estimate_memsize         = gimp_drawable_real_estimate_memsize;
+  klass->update_all               = gimp_drawable_real_update_all;
+  klass->invalidate_boundary      = NULL;
+  klass->get_active_components    = NULL;
+  klass->get_active_mask          = gimp_drawable_real_get_active_mask;
+  klass->supports_alpha           = gimp_drawable_real_supports_alpha;
+  klass->convert_type             = gimp_drawable_real_convert_type;
+  klass->apply_buffer             = gimp_drawable_real_apply_buffer;
+  klass->get_buffer               = gimp_drawable_real_get_buffer;
+  klass->set_buffer               = gimp_drawable_real_set_buffer;
+  klass->get_bounding_box         = gimp_drawable_real_get_bounding_box;
+  klass->push_undo                = gimp_drawable_real_push_undo;
+  klass->swap_pixels              = gimp_drawable_real_swap_pixels;
+  klass->get_source_node          = gimp_drawable_real_get_source_node;
+
+  g_object_class_override_property (object_class, PROP_BUFFER, "buffer");
+}
+
+static void
+gimp_drawable_init (GimpDrawable *drawable)
+{
+  drawable->private = gimp_drawable_get_instance_private (drawable);
+
+  drawable->private->filter_stack = gimp_filter_stack_new (GIMP_TYPE_FILTER);
+}
+
+/* sorry for the evil casts */
+
+static void
+gimp_color_managed_iface_init (GimpColorManagedInterface *iface)
+{
+  iface->get_icc_profile   = gimp_drawable_get_icc_profile;
+  iface->get_color_profile = gimp_drawable_get_color_profile;
+  iface->profile_changed   = gimp_drawable_profile_changed;
+}
+
+static void
+gimp_pickable_iface_init (GimpPickableInterface *iface)
+{
+  iface->get_image             = (GimpImage     * (*) (GimpPickable *pickable)) gimp_item_get_image;
+  iface->get_format            = (const Babl    * (*) (GimpPickable *pickable)) gimp_drawable_get_format;
+  iface->get_format_with_alpha = (const Babl    * (*) (GimpPickable *pickable)) gimp_drawable_get_format_with_alpha;
+  iface->get_buffer            = (GeglBuffer    * (*) (GimpPickable *pickable)) gimp_drawable_get_buffer;
+  iface->get_pixel_at          = gimp_drawable_get_pixel_at;
+  iface->get_pixel_average     = gimp_drawable_get_pixel_average;
+}
+
+static void
+gimp_drawable_dispose (GObject *object)
+{
+  GimpDrawable *drawable = GIMP_DRAWABLE (object);
+
+  if (gimp_drawable_get_floating_sel (drawable))
+    gimp_drawable_detach_floating_sel (drawable);
+
+  G_OBJECT_CLASS (parent_class)->dispose (object);
+}
+
+static void
+gimp_drawable_finalize (GObject *object)
+{
+  GimpDrawable *drawable = GIMP_DRAWABLE (object);
+
+  while (drawable->private->paint_count)
+    gimp_drawable_end_paint (drawable);
+
+  g_clear_object (&drawable->private->buffer);
+
+  gimp_drawable_free_shadow_buffer (drawable);
+
+  g_clear_object (&drawable->private->source_node);
+  g_clear_object (&drawable->private->buffer_source_node);
+  g_clear_object (&drawable->private->filter_stack);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gimp_drawable_set_property (GObject      *object,
+                            guint         property_id,
+                            const GValue *value,
+                            GParamSpec   *pspec)
+{
+  switch (property_id)
+    {
+    case PROP_BUFFER:
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_drawable_get_property (GObject    *object,
+                            guint       property_id,
+                            GValue     *value,
+                            GParamSpec *pspec)
+{
+  GimpDrawable *drawable = GIMP_DRAWABLE (object);
+
+  switch (property_id)
+    {
+    case PROP_BUFFER:
+      g_value_set_object (value, drawable->private->buffer);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static gint64
+gimp_drawable_get_memsize (GimpObject *object,
+                           gint64     *gui_size)
+{
+  GimpDrawable *drawable = GIMP_DRAWABLE (object);
+  gint64        memsize  = 0;
+
+  memsize += gimp_gegl_buffer_get_memsize (gimp_drawable_get_buffer (drawable));
+  memsize += gimp_gegl_buffer_get_memsize (drawable->private->shadow);
+
+  return memsize + GIMP_OBJECT_CLASS (parent_class)->get_memsize (object,
+                                                                  gui_size);
+}
+
+static gboolean
+gimp_drawable_get_size (GimpViewable *viewable,
+                        gint         *width,
+                        gint         *height)
+{
+  GimpItem *item = GIMP_ITEM (viewable);
+
+  *width  = gimp_item_get_width  (item);
+  *height = gimp_item_get_height (item);
+
+  return TRUE;
+}
+
+static void
+gimp_drawable_preview_freeze (GimpViewable *viewable)
+{
+  GimpViewable *parent = gimp_viewable_get_parent (viewable);
+
+  if (! parent && gimp_item_is_attached (GIMP_ITEM (viewable)))
+    parent = GIMP_VIEWABLE (gimp_item_get_image (GIMP_ITEM (viewable)));
+
+  if (parent)
+    gimp_viewable_preview_freeze (parent);
+}
+
+static void
+gimp_drawable_preview_thaw (GimpViewable *viewable)
+{
+  GimpViewable *parent = gimp_viewable_get_parent (viewable);
+
+  if (! parent && gimp_item_is_attached (GIMP_ITEM (viewable)))
+    parent = GIMP_VIEWABLE (gimp_item_get_image (GIMP_ITEM (viewable)));
+
+  if (parent)
+    gimp_viewable_preview_thaw (parent);
+}
+
+static GeglNode *
+gimp_drawable_get_node (GimpFilter *filter)
+{
+  GimpDrawable *drawable = GIMP_DRAWABLE (filter);
+  GeglNode     *node;
+  GeglNode     *input;
+  GeglNode     *output;
+
+  node = GIMP_FILTER_CLASS (parent_class)->get_node (filter);
+
+  g_warn_if_fail (drawable->private->mode_node == NULL);
+
+  drawable->private->mode_node =
+    gegl_node_new_child (node,
+                         "operation", "gimp:normal",
+                         NULL);
+
+  input  = gegl_node_get_input_proxy  (node, "input");
+  output = gegl_node_get_output_proxy (node, "output");
+
+  gegl_node_connect_to (input,                        "output",
+                        drawable->private->mode_node, "input");
+  gegl_node_connect_to (drawable->private->mode_node, "output",
+                        output,                       "input");
+
+  return node;
+}
+
+static void
+gimp_drawable_removed (GimpItem *item)
+{
+  GimpDrawable *drawable = GIMP_DRAWABLE (item);
+
+  gimp_drawable_free_shadow_buffer (drawable);
+
+  if (GIMP_ITEM_CLASS (parent_class)->removed)
+    GIMP_ITEM_CLASS (parent_class)->removed (item);
+}
+
+static GimpItem *
+gimp_drawable_duplicate (GimpItem *item,
+                         GType     new_type)
+{
+  GimpItem *new_item;
+
+  g_return_val_if_fail (g_type_is_a (new_type, GIMP_TYPE_DRAWABLE), NULL);
+
+  new_item = GIMP_ITEM_CLASS (parent_class)->duplicate (item, new_type);
+
+  if (GIMP_IS_DRAWABLE (new_item))
+    {
+      GimpDrawable  *drawable     = GIMP_DRAWABLE (item);
+      GimpDrawable  *new_drawable = GIMP_DRAWABLE (new_item);
+      GeglBuffer    *new_buffer;
+
+      new_buffer = gimp_gegl_buffer_dup (gimp_drawable_get_buffer (drawable));
+
+      gimp_drawable_set_buffer (new_drawable, FALSE, NULL, new_buffer);
+      g_object_unref (new_buffer);
+    }
+
+  return new_item;
+}
+
+static void
+gimp_drawable_scale (GimpItem              *item,
+                     gint                   new_width,
+                     gint                   new_height,
+                     gint                   new_offset_x,
+                     gint                   new_offset_y,
+                     GimpInterpolationType  interpolation_type,
+                     GimpProgress          *progress)
+{
+  GimpDrawable *drawable = GIMP_DRAWABLE (item);
+  GeglBuffer   *new_buffer;
+
+  new_buffer = gegl_buffer_new (GEGL_RECTANGLE (0, 0,
+                                                new_width, new_height),
+                                gimp_drawable_get_format (drawable));
+
+  gimp_gegl_apply_scale (gimp_drawable_get_buffer (drawable),
+                         progress, C_("undo-type", "Scale"),
+                         new_buffer,
+                         interpolation_type,
+                         ((gdouble) new_width /
+                          gimp_item_get_width  (item)),
+                         ((gdouble) new_height /
+                          gimp_item_get_height (item)));
+
+  gimp_drawable_set_buffer_full (drawable, gimp_item_is_attached (item), NULL,
+                                 new_buffer,
+                                 GEGL_RECTANGLE (new_offset_x, new_offset_y,
+                                                 0,            0),
+                                 TRUE);
+  g_object_unref (new_buffer);
+}
+
+static void
+gimp_drawable_resize (GimpItem     *item,
+                      GimpContext  *context,
+                      GimpFillType  fill_type,
+                      gint          new_width,
+                      gint          new_height,
+                      gint          offset_x,
+                      gint          offset_y)
+{
+  GimpDrawable *drawable = GIMP_DRAWABLE (item);
+  GeglBuffer   *new_buffer;
+  gint          new_offset_x;
+  gint          new_offset_y;
+  gint          copy_x, copy_y;
+  gint          copy_width, copy_height;
+  gboolean      intersect;
+
+  /*  if the size doesn't change, this is a nop  */
+  if (new_width  == gimp_item_get_width  (item) &&
+      new_height == gimp_item_get_height (item) &&
+      offset_x   == 0                           &&
+      offset_y   == 0)
+    return;
+
+  new_offset_x = gimp_item_get_offset_x (item) - offset_x;
+  new_offset_y = gimp_item_get_offset_y (item) - offset_y;
+
+  intersect = gimp_rectangle_intersect (gimp_item_get_offset_x (item),
+                                        gimp_item_get_offset_y (item),
+                                        gimp_item_get_width (item),
+                                        gimp_item_get_height (item),
+                                        new_offset_x,
+                                        new_offset_y,
+                                        new_width,
+                                        new_height,
+                                        &copy_x,
+                                        &copy_y,
+                                        &copy_width,
+                                        &copy_height);
+
+  new_buffer = gegl_buffer_new (GEGL_RECTANGLE (0, 0,
+                                                new_width, new_height),
+                                gimp_drawable_get_format (drawable));
+
+  if (! intersect              ||
+      copy_width  != new_width ||
+      copy_height != new_height)
+    {
+      /*  Clear the new buffer if needed  */
+
+      GimpRGB      color;
+      GimpPattern *pattern;
+
+      gimp_get_fill_params (context, fill_type, &color, &pattern, NULL);
+      gimp_drawable_fill_buffer (drawable, new_buffer,
+                                 &color, pattern, 0, 0);
+    }
+
+  if (intersect && copy_width && copy_height)
+    {
+      /*  Copy the pixels in the intersection  */
+      gimp_gegl_buffer_copy (
+        gimp_drawable_get_buffer (drawable),
+        GEGL_RECTANGLE (copy_x - gimp_item_get_offset_x (item),
+                        copy_y - gimp_item_get_offset_y (item),
+                        copy_width,
+                        copy_height), GEGL_ABYSS_NONE,
+        new_buffer,
+        GEGL_RECTANGLE (copy_x - new_offset_x,
+                        copy_y - new_offset_y, 0, 0));
+    }
+
+  gimp_drawable_set_buffer_full (drawable, gimp_item_is_attached (item), NULL,
+                                 new_buffer,
+                                 GEGL_RECTANGLE (new_offset_x, new_offset_y,
+                                                 0,            0),
+                                 TRUE);
+  g_object_unref (new_buffer);
+}
+
+static void
+gimp_drawable_flip (GimpItem            *item,
+                    GimpContext         *context,
+                    GimpOrientationType  flip_type,
+                    gdouble              axis,
+                    gboolean             clip_result)
+{
+  GimpDrawable     *drawable = GIMP_DRAWABLE (item);
+  GeglBuffer       *buffer;
+  GimpColorProfile *buffer_profile;
+  gint              off_x, off_y;
+  gint              new_off_x, new_off_y;
+
+  gimp_item_get_offset (item, &off_x, &off_y);
+
+  buffer = gimp_drawable_transform_buffer_flip (drawable, context,
+                                                gimp_drawable_get_buffer (drawable),
+                                                off_x, off_y,
+                                                flip_type, axis,
+                                                clip_result,
+                                                &buffer_profile,
+                                                &new_off_x, &new_off_y);
+
+  if (buffer)
+    {
+      gimp_drawable_transform_paste (drawable, buffer, buffer_profile,
+                                     new_off_x, new_off_y, FALSE);
+      g_object_unref (buffer);
+    }
+}
+
+static void
+gimp_drawable_rotate (GimpItem         *item,
+                      GimpContext      *context,
+                      GimpRotationType  rotate_type,
+                      gdouble           center_x,
+                      gdouble           center_y,
+                      gboolean          clip_result)
+{
+  GimpDrawable     *drawable = GIMP_DRAWABLE (item);
+  GeglBuffer       *buffer;
+  GimpColorProfile *buffer_profile;
+  gint              off_x, off_y;
+  gint              new_off_x, new_off_y;
+
+  gimp_item_get_offset (item, &off_x, &off_y);
+
+  buffer = gimp_drawable_transform_buffer_rotate (drawable, context,
+                                                  gimp_drawable_get_buffer (drawable),
+                                                  off_x, off_y,
+                                                  rotate_type, center_x, center_y,
+                                                  clip_result,
+                                                  &buffer_profile,
+                                                  &new_off_x, &new_off_y);
+
+  if (buffer)
+    {
+      gimp_drawable_transform_paste (drawable, buffer, buffer_profile,
+                                     new_off_x, new_off_y, FALSE);
+      g_object_unref (buffer);
+    }
+}
+
+static void
+gimp_drawable_transform (GimpItem               *item,
+                         GimpContext            *context,
+                         const GimpMatrix3      *matrix,
+                         GimpTransformDirection  direction,
+                         GimpInterpolationType   interpolation_type,
+                         GimpTransformResize     clip_result,
+                         GimpProgress           *progress)
+{
+  GimpDrawable     *drawable = GIMP_DRAWABLE (item);
+  GeglBuffer       *buffer;
+  GimpColorProfile *buffer_profile;
+  gint              off_x, off_y;
+  gint              new_off_x, new_off_y;
+
+  gimp_item_get_offset (item, &off_x, &off_y);
+
+  buffer = gimp_drawable_transform_buffer_affine (drawable, context,
+                                                  gimp_drawable_get_buffer (drawable),
+                                                  off_x, off_y,
+                                                  matrix, direction,
+                                                  interpolation_type,
+                                                  clip_result,
+                                                  &buffer_profile,
+                                                  &new_off_x, &new_off_y,
+                                                  progress);
+
+  if (buffer)
+    {
+      gimp_drawable_transform_paste (drawable, buffer, buffer_profile,
+                                     new_off_x, new_off_y, FALSE);
+      g_object_unref (buffer);
+    }
+}
+
+static const guint8 *
+gimp_drawable_get_icc_profile (GimpColorManaged *managed,
+                               gsize            *len)
+{
+  GimpColorProfile *profile = gimp_color_managed_get_color_profile (managed);
+
+  return gimp_color_profile_get_icc_profile (profile, len);
+}
+
+static GimpColorProfile *
+gimp_drawable_get_color_profile (GimpColorManaged *managed)
+{
+  const Babl *format = gimp_drawable_get_format (GIMP_DRAWABLE (managed));
+
+  return gimp_babl_format_get_color_profile (format);
+}
+
+static void
+gimp_drawable_profile_changed (GimpColorManaged *managed)
+{
+  gimp_viewable_invalidate_preview (GIMP_VIEWABLE (managed));
+}
+
+static gboolean
+gimp_drawable_get_pixel_at (GimpPickable *pickable,
+                            gint          x,
+                            gint          y,
+                            const Babl   *format,
+                            gpointer      pixel)
+{
+  GimpDrawable *drawable = GIMP_DRAWABLE (pickable);
+
+  /* do not make this a g_return_if_fail() */
+  if (x < 0 || x >= gimp_item_get_width  (GIMP_ITEM (drawable)) ||
+      y < 0 || y >= gimp_item_get_height (GIMP_ITEM (drawable)))
+    return FALSE;
+
+  gegl_buffer_sample (gimp_drawable_get_buffer (drawable),
+                      x, y, NULL, pixel, format,
+                      GEGL_SAMPLER_NEAREST, GEGL_ABYSS_NONE);
+
+  return TRUE;
+}
+
+static void
+gimp_drawable_get_pixel_average (GimpPickable        *pickable,
+                                 const GeglRectangle *rect,
+                                 const Babl          *format,
+                                 gpointer             pixel)
+{
+  GimpDrawable *drawable = GIMP_DRAWABLE (pickable);
+
+  return gimp_gegl_average_color (gimp_drawable_get_buffer (drawable),
+                                  rect, TRUE, GEGL_ABYSS_NONE, format, pixel);
+}
+
+static void
+gimp_drawable_real_update (GimpDrawable *drawable,
+                           gint          x,
+                           gint          y,
+                           gint          width,
+                           gint          height)
+{
+  gimp_viewable_invalidate_preview (GIMP_VIEWABLE (drawable));
+}
+
+static gint64
+gimp_drawable_real_estimate_memsize (GimpDrawable      *drawable,
+                                     GimpComponentType  component_type,
+                                     gint               width,
+                                     gint               height)
+{
+  GimpImage  *image  = gimp_item_get_image (GIMP_ITEM (drawable));
+  gboolean    linear = gimp_drawable_get_linear (drawable);
+  const Babl *format;
+
+  format = gimp_image_get_format (image,
+                                  gimp_drawable_get_base_type (drawable),
+                                  gimp_babl_precision (component_type, linear),
+                                  gimp_drawable_has_alpha (drawable));
+
+  return (gint64) babl_format_get_bytes_per_pixel (format) * width * height;
+}
+
+static void
+gimp_drawable_real_update_all (GimpDrawable *drawable)
+{
+  gimp_drawable_update (drawable, 0, 0, -1, -1);
+}
+
+static GimpComponentMask
+gimp_drawable_real_get_active_mask (GimpDrawable *drawable)
+{
+  /*  Return all, because that skips the component mask op when painting  */
+  return GIMP_COMPONENT_MASK_ALL;
+}
+
+static gboolean
+gimp_drawable_real_supports_alpha (GimpDrawable *drawable)
+{
+  return FALSE;
+}
+
+/* FIXME: this default impl is currently unused because no subclass
+ * chains up. the goal is to handle the almost identical subclass code
+ * here again.
+ */
+static void
+gimp_drawable_real_convert_type (GimpDrawable      *drawable,
+                                 GimpImage         *dest_image,
+                                 const Babl        *new_format,
+                                 GimpColorProfile  *dest_profile,
+                                 GeglDitherMethod   layer_dither_type,
+                                 GeglDitherMethod   mask_dither_type,
+                                 gboolean           push_undo,
+                                 GimpProgress      *progress)
+{
+  GeglBuffer *dest_buffer;
+
+  dest_buffer =
+    gegl_buffer_new (GEGL_RECTANGLE (0, 0,
+                                     gimp_item_get_width  (GIMP_ITEM (drawable)),
+                                     gimp_item_get_height (GIMP_ITEM (drawable))),
+                     new_format);
+
+  gimp_gegl_buffer_copy (
+    gimp_drawable_get_buffer (drawable), NULL, GEGL_ABYSS_NONE,
+    dest_buffer, NULL);
+
+  gimp_drawable_set_buffer (drawable, push_undo, NULL, dest_buffer);
+  g_object_unref (dest_buffer);
+}
+
+static GeglBuffer *
+gimp_drawable_real_get_buffer (GimpDrawable *drawable)
+{
+  return drawable->private->buffer;
+}
+
+static void
+gimp_drawable_real_set_buffer (GimpDrawable        *drawable,
+                               gboolean             push_undo,
+                               const gchar         *undo_desc,
+                               GeglBuffer          *buffer,
+                               const GeglRectangle *bounds)
+{
+  GimpItem   *item          = GIMP_ITEM (drawable);
+  const Babl *old_format    = NULL;
+  gint        old_has_alpha = -1;
+
+  g_object_freeze_notify (G_OBJECT (drawable));
+
+  gimp_drawable_invalidate_boundary (drawable);
+
+  if (push_undo)
+    gimp_image_undo_push_drawable_mod (gimp_item_get_image (item), undo_desc,
+                                       drawable, FALSE);
+
+  if (drawable->private->buffer)
+    {
+      old_format    = gimp_drawable_get_format (drawable);
+      old_has_alpha = gimp_drawable_has_alpha (drawable);
+    }
+
+  g_set_object (&drawable->private->buffer, buffer);
+
+  if (drawable->private->buffer_source_node)
+    gegl_node_set (drawable->private->buffer_source_node,
+                   "buffer", gimp_drawable_get_buffer (drawable),
+                   NULL);
+
+  gimp_item_set_offset (item, bounds->x, bounds->y);
+  gimp_item_set_size (item,
+                      bounds->width  ? bounds->width :
+                                       gegl_buffer_get_width (buffer),
+                      bounds->height ? bounds->height :
+                                       gegl_buffer_get_height (buffer));
+
+  gimp_drawable_update_bounding_box (drawable);
+
+  if (gimp_drawable_get_format (drawable) != old_format)
+    gimp_drawable_format_changed (drawable);
+
+  if (gimp_drawable_has_alpha (drawable) != old_has_alpha)
+    gimp_drawable_alpha_changed (drawable);
+
+  g_object_notify (G_OBJECT (drawable), "buffer");
+
+  g_object_thaw_notify (G_OBJECT (drawable));
+}
+
+static GeglRectangle
+gimp_drawable_real_get_bounding_box (GimpDrawable *drawable)
+{
+  return gegl_node_get_bounding_box (gimp_drawable_get_source_node (drawable));
+}
+
+static void
+gimp_drawable_real_push_undo (GimpDrawable *drawable,
+                              const gchar  *undo_desc,
+                              GeglBuffer   *buffer,
+                              gint          x,
+                              gint          y,
+                              gint          width,
+                              gint          height)
+{
+  GimpImage *image;
+
+  if (! buffer)
+    {
+      GeglBuffer    *drawable_buffer = gimp_drawable_get_buffer (drawable);
+      GeglRectangle  drawable_rect;
+
+      gegl_rectangle_align_to_buffer (
+        &drawable_rect,
+        GEGL_RECTANGLE (x, y, width, height),
+        drawable_buffer,
+        GEGL_RECTANGLE_ALIGNMENT_SUPERSET);
+
+      x      = drawable_rect.x;
+      y      = drawable_rect.y;
+      width  = drawable_rect.width;
+      height = drawable_rect.height;
+
+      buffer = gegl_buffer_new (GEGL_RECTANGLE (0, 0, width, height),
+                                gimp_drawable_get_format (drawable));
+
+      gimp_gegl_buffer_copy (
+        drawable_buffer,
+        &drawable_rect, GEGL_ABYSS_NONE,
+        buffer,
+        GEGL_RECTANGLE (0, 0, 0, 0));
+    }
+  else
+    {
+      g_object_ref (buffer);
+    }
+
+  image = gimp_item_get_image (GIMP_ITEM (drawable));
+
+  gimp_image_undo_push_drawable (image,
+                                 undo_desc, drawable,
+                                 buffer, x, y);
+
+  g_object_unref (buffer);
+}
+
+static void
+gimp_drawable_real_swap_pixels (GimpDrawable *drawable,
+                                GeglBuffer   *buffer,
+                                gint          x,
+                                gint          y)
+{
+  GeglBuffer *tmp;
+  gint        width  = gegl_buffer_get_width (buffer);
+  gint        height = gegl_buffer_get_height (buffer);
+
+  tmp = gimp_gegl_buffer_dup (buffer);
+
+  gimp_gegl_buffer_copy (gimp_drawable_get_buffer (drawable),
+                         GEGL_RECTANGLE (x, y, width, height), GEGL_ABYSS_NONE,
+                         buffer,
+                         GEGL_RECTANGLE (0, 0, 0, 0));
+  gimp_gegl_buffer_copy (tmp,
+                         GEGL_RECTANGLE (0, 0, width, height), GEGL_ABYSS_NONE,
+                         gimp_drawable_get_buffer (drawable),
+                         GEGL_RECTANGLE (x, y, 0, 0));
+
+  g_object_unref (tmp);
+
+  gimp_drawable_update (drawable, x, y, width, height);
+}
+
+static GeglNode *
+gimp_drawable_real_get_source_node (GimpDrawable *drawable)
+{
+  g_warn_if_fail (drawable->private->buffer_source_node == NULL);
+
+  drawable->private->buffer_source_node =
+    gegl_node_new_child (NULL,
+                         "operation", "gimp:buffer-source-validate",
+                         "buffer",    gimp_drawable_get_buffer (drawable),
+                         NULL);
+
+  return g_object_ref (drawable->private->buffer_source_node);
+}
+
+static void
+gimp_drawable_format_changed (GimpDrawable *drawable)
+{
+  g_signal_emit (drawable, gimp_drawable_signals[FORMAT_CHANGED], 0);
+}
+
+static void
+gimp_drawable_alpha_changed (GimpDrawable *drawable)
+{
+  g_signal_emit (drawable, gimp_drawable_signals[ALPHA_CHANGED], 0);
+}
+
+
+/*  public functions  */
+
+GimpDrawable *
+gimp_drawable_new (GType          type,
+                   GimpImage     *image,
+                   const gchar   *name,
+                   gint           offset_x,
+                   gint           offset_y,
+                   gint           width,
+                   gint           height,
+                   const Babl    *format)
+{
+  GimpDrawable *drawable;
+  GeglBuffer   *buffer;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (g_type_is_a (type, GIMP_TYPE_DRAWABLE), NULL);
+  g_return_val_if_fail (width > 0 && height > 0, NULL);
+  g_return_val_if_fail (format != NULL, NULL);
+
+  drawable = GIMP_DRAWABLE (gimp_item_new (type,
+                                           image, name,
+                                           offset_x, offset_y,
+                                           width, height));
+
+  buffer = gegl_buffer_new (GEGL_RECTANGLE (0, 0, width, height), format);
+
+  gimp_drawable_set_buffer (drawable, FALSE, NULL, buffer);
+  g_object_unref (buffer);
+
+  return drawable;
+}
+
+gint64
+gimp_drawable_estimate_memsize (GimpDrawable      *drawable,
+                                GimpComponentType  component_type,
+                                gint               width,
+                                gint               height)
+{
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), 0);
+
+  return GIMP_DRAWABLE_GET_CLASS (drawable)->estimate_memsize (drawable,
+                                                               component_type,
+                                                               width, height);
+}
+
+void
+gimp_drawable_update (GimpDrawable *drawable,
+                      gint          x,
+                      gint          y,
+                      gint          width,
+                      gint          height)
+{
+  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
+
+  if (width < 0)
+    {
+      GeglRectangle bounding_box;
+
+      bounding_box = gimp_drawable_get_bounding_box (drawable);
+
+      x     = bounding_box.x;
+      width = bounding_box.width;
+    }
+
+  if (height < 0)
+    {
+      GeglRectangle bounding_box;
+
+      bounding_box = gimp_drawable_get_bounding_box (drawable);
+
+      y      = bounding_box.y;
+      height = bounding_box.height;
+    }
+
+  if (drawable->private->paint_count == 0)
+    {
+      g_signal_emit (drawable, gimp_drawable_signals[UPDATE], 0,
+                     x, y, width, height);
+    }
+  else
+    {
+      GeglRectangle rect;
+
+      if (gegl_rectangle_intersect (
+            &rect,
+            GEGL_RECTANGLE (x, y, width, height),
+            GEGL_RECTANGLE (0, 0,
+                            gimp_item_get_width  (GIMP_ITEM (drawable)),
+                            gimp_item_get_height (GIMP_ITEM (drawable)))))
+        {
+          GeglRectangle aligned_rect;
+
+          gegl_rectangle_align_to_buffer (&aligned_rect, &rect,
+                                          gimp_drawable_get_buffer (drawable),
+                                          GEGL_RECTANGLE_ALIGNMENT_SUPERSET);
+
+          if (drawable->private->paint_copy_region)
+            {
+              cairo_region_union_rectangle (
+                drawable->private->paint_copy_region,
+                (const cairo_rectangle_int_t *) &aligned_rect);
+            }
+          else
+            {
+              drawable->private->paint_copy_region =
+                cairo_region_create_rectangle (
+                  (const cairo_rectangle_int_t *) &aligned_rect);
+            }
+
+          gegl_rectangle_align (&aligned_rect, &rect,
+                                GEGL_RECTANGLE (0, 0,
+                                                PAINT_UPDATE_CHUNK_WIDTH,
+                                                PAINT_UPDATE_CHUNK_HEIGHT),
+                                GEGL_RECTANGLE_ALIGNMENT_SUPERSET);
+
+          if (drawable->private->paint_update_region)
+            {
+              cairo_region_union_rectangle (
+                drawable->private->paint_update_region,
+                (const cairo_rectangle_int_t *) &aligned_rect);
+            }
+          else
+            {
+              drawable->private->paint_update_region =
+                cairo_region_create_rectangle (
+                  (const cairo_rectangle_int_t *) &aligned_rect);
+            }
+        }
+    }
+}
+
+void
+gimp_drawable_update_all (GimpDrawable *drawable)
+{
+  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
+
+  GIMP_DRAWABLE_GET_CLASS (drawable)->update_all (drawable);
+}
+
+void
+gimp_drawable_invalidate_boundary (GimpDrawable *drawable)
+{
+  GimpDrawableClass *drawable_class;
+
+  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
+
+  drawable_class = GIMP_DRAWABLE_GET_CLASS (drawable);
+
+  if (drawable_class->invalidate_boundary)
+    drawable_class->invalidate_boundary (drawable);
+}
+
+void
+gimp_drawable_get_active_components (GimpDrawable *drawable,
+                                     gboolean     *active)
+{
+  GimpDrawableClass *drawable_class;
+
+  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
+  g_return_if_fail (active != NULL);
+
+  drawable_class = GIMP_DRAWABLE_GET_CLASS (drawable);
+
+  if (drawable_class->get_active_components)
+    drawable_class->get_active_components (drawable, active);
+}
+
+GimpComponentMask
+gimp_drawable_get_active_mask (GimpDrawable *drawable)
+{
+  GimpComponentMask mask;
+
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), 0);
+
+  mask = GIMP_DRAWABLE_GET_CLASS (drawable)->get_active_mask (drawable);
+
+  /* if the drawable doesn't have an alpha channel, the value of the mask's
+   * alpha-bit doesn't matter, however, we'd like to have a fully-clear or
+   * fully-set mask whenever possible, since it allows us to skip component
+   * masking altogether.  we therefore set or clear the alpha bit, depending on
+   * the state of the other bits, so that it never gets in the way of a uniform
+   * mask.
+   */
+  if (! gimp_drawable_has_alpha (drawable))
+    {
+      if (mask & ~GIMP_COMPONENT_MASK_ALPHA)
+        mask |= GIMP_COMPONENT_MASK_ALPHA;
+      else
+        mask &= ~GIMP_COMPONENT_MASK_ALPHA;
+    }
+
+  return mask;
+}
+
+gboolean
+gimp_drawable_supports_alpha (GimpDrawable *drawable)
+{
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), FALSE);
+
+  return GIMP_DRAWABLE_GET_CLASS (drawable)->supports_alpha (drawable);
+}
+
+void
+gimp_drawable_convert_type (GimpDrawable      *drawable,
+                            GimpImage         *dest_image,
+                            GimpImageBaseType  new_base_type,
+                            GimpPrecision      new_precision,
+                            gboolean           new_has_alpha,
+                            GimpColorProfile  *dest_profile,
+                            GeglDitherMethod   layer_dither_type,
+                            GeglDitherMethod   mask_dither_type,
+                            gboolean           push_undo,
+                            GimpProgress      *progress)
+{
+  const Babl *old_format;
+  const Babl *new_format;
+  gint        old_bits;
+  gint        new_bits;
+
+  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
+  g_return_if_fail (GIMP_IS_IMAGE (dest_image));
+  g_return_if_fail (new_base_type != gimp_drawable_get_base_type (drawable) ||
+                    new_precision != gimp_drawable_get_precision (drawable) ||
+                    new_has_alpha != gimp_drawable_has_alpha (drawable)     ||
+                    dest_profile);
+  g_return_if_fail (dest_profile == NULL || GIMP_IS_COLOR_PROFILE (dest_profile));
+  g_return_if_fail (progress == NULL || GIMP_IS_PROGRESS (progress));
+
+  if (! gimp_item_is_attached (GIMP_ITEM (drawable)))
+    push_undo = FALSE;
+
+  old_format = gimp_drawable_get_format (drawable);
+  new_format = gimp_image_get_format (dest_image,
+                                      new_base_type,
+                                      new_precision,
+                                      new_has_alpha);
+
+  old_bits = (babl_format_get_bytes_per_pixel (old_format) * 8 /
+              babl_format_get_n_components (old_format));
+  new_bits = (babl_format_get_bytes_per_pixel (new_format) * 8 /
+              babl_format_get_n_components (new_format));
+
+  if (old_bits <= new_bits || new_bits > 16)
+    {
+      /*  don't dither if we are converting to a higher bit depth,
+       *  or to more than 16 bits (gegl:dither only does
+       *  16 bits).
+       */
+      layer_dither_type = GEGL_DITHER_NONE;
+      mask_dither_type  = GEGL_DITHER_NONE;
+    }
+
+  GIMP_DRAWABLE_GET_CLASS (drawable)->convert_type (drawable, dest_image,
+                                                    new_format,
+                                                    dest_profile,
+                                                    layer_dither_type,
+                                                    mask_dither_type,
+                                                    push_undo,
+                                                    progress);
+
+  if (progress)
+    gimp_progress_set_value (progress, 1.0);
+}
+
+void
+gimp_drawable_apply_buffer (GimpDrawable           *drawable,
+                            GeglBuffer             *buffer,
+                            const GeglRectangle    *buffer_region,
+                            gboolean                push_undo,
+                            const gchar            *undo_desc,
+                            gdouble                 opacity,
+                            GimpLayerMode           mode,
+                            GimpLayerColorSpace     blend_space,
+                            GimpLayerColorSpace     composite_space,
+                            GimpLayerCompositeMode  composite_mode,
+                            GeglBuffer             *base_buffer,
+                            gint                    base_x,
+                            gint                    base_y)
+{
+  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
+  g_return_if_fail (gimp_item_is_attached (GIMP_ITEM (drawable)));
+  g_return_if_fail (GEGL_IS_BUFFER (buffer));
+  g_return_if_fail (buffer_region != NULL);
+  g_return_if_fail (base_buffer == NULL || GEGL_IS_BUFFER (base_buffer));
+
+  GIMP_DRAWABLE_GET_CLASS (drawable)->apply_buffer (drawable, buffer,
+                                                    buffer_region,
+                                                    push_undo, undo_desc,
+                                                    opacity, mode,
+                                                    blend_space,
+                                                    composite_space,
+                                                    composite_mode,
+                                                    base_buffer,
+                                                    base_x, base_y);
+}
+
+GeglBuffer *
+gimp_drawable_get_buffer (GimpDrawable *drawable)
+{
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
+
+  if (drawable->private->paint_count == 0)
+    return GIMP_DRAWABLE_GET_CLASS (drawable)->get_buffer (drawable);
+  else
+    return drawable->private->paint_buffer;
+}
+
+void
+gimp_drawable_set_buffer (GimpDrawable *drawable,
+                          gboolean      push_undo,
+                          const gchar  *undo_desc,
+                          GeglBuffer   *buffer)
+{
+  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
+  g_return_if_fail (GEGL_IS_BUFFER (buffer));
+
+  if (! gimp_item_is_attached (GIMP_ITEM (drawable)))
+    push_undo = FALSE;
+
+  gimp_drawable_set_buffer_full (drawable, push_undo, undo_desc, buffer, NULL,
+                                 TRUE);
+}
+
+void
+gimp_drawable_set_buffer_full (GimpDrawable        *drawable,
+                               gboolean             push_undo,
+                               const gchar         *undo_desc,
+                               GeglBuffer          *buffer,
+                               const GeglRectangle *bounds,
+                               gboolean             update)
+{
+  GimpItem      *item;
+  GeglRectangle  curr_bounds;
+
+  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
+  g_return_if_fail (GEGL_IS_BUFFER (buffer));
+
+  item = GIMP_ITEM (drawable);
+
+  if (! gimp_item_is_attached (GIMP_ITEM (drawable)))
+    push_undo = FALSE;
+
+  if (! bounds)
+    {
+      gimp_item_get_offset (GIMP_ITEM (drawable),
+                            &curr_bounds.x, &curr_bounds.y);
+
+      curr_bounds.width  = 0;
+      curr_bounds.height = 0;
+
+      bounds = &curr_bounds;
+    }
+
+  if (update && gimp_drawable_get_buffer (drawable))
+    {
+      GeglBuffer    *old_buffer = gimp_drawable_get_buffer (drawable);
+      GeglRectangle  old_extent;
+      GeglRectangle  new_extent;
+
+      old_extent = *gegl_buffer_get_extent (old_buffer);
+      old_extent.x += gimp_item_get_offset_x (item);
+      old_extent.y += gimp_item_get_offset_x (item);
+
+      new_extent = *gegl_buffer_get_extent (buffer);
+      new_extent.x += bounds->x;
+      new_extent.y += bounds->y;
+
+      if (! gegl_rectangle_equal (&old_extent, &new_extent))
+        gimp_drawable_update (drawable, 0, 0, -1, -1);
+    }
+
+  g_object_freeze_notify (G_OBJECT (drawable));
+
+  GIMP_DRAWABLE_GET_CLASS (drawable)->set_buffer (drawable,
+                                                  push_undo, undo_desc,
+                                                  buffer, bounds);
+
+  g_object_thaw_notify (G_OBJECT (drawable));
+
+  if (update)
+    gimp_drawable_update (drawable, 0, 0, -1, -1);
+}
+
+void
+gimp_drawable_steal_buffer (GimpDrawable *drawable,
+                            GimpDrawable *src_drawable)
+{
+  GeglBuffer *buffer;
+  GeglBuffer *replacement_buffer;
+
+  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
+  g_return_if_fail (GIMP_IS_DRAWABLE (src_drawable));
+
+  buffer = gimp_drawable_get_buffer (src_drawable);
+
+  g_return_if_fail (buffer != NULL);
+
+  g_object_ref (buffer);
+
+  replacement_buffer = gegl_buffer_new (GEGL_RECTANGLE (0, 0, 1, 1),
+                                        gegl_buffer_get_format (buffer));
+
+  gimp_drawable_set_buffer (src_drawable, FALSE, NULL, replacement_buffer);
+  gimp_drawable_set_buffer (drawable,     FALSE, NULL, buffer);
+
+  g_object_unref (replacement_buffer);
+  g_object_unref (buffer);
+}
+
+GeglNode *
+gimp_drawable_get_source_node (GimpDrawable *drawable)
+{
+  GeglNode *input;
+  GeglNode *source;
+  GeglNode *filter;
+  GeglNode *output;
+
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
+
+  if (drawable->private->source_node)
+    return drawable->private->source_node;
+
+  drawable->private->source_node = gegl_node_new ();
+
+  input = gegl_node_get_input_proxy (drawable->private->source_node, "input");
+
+  source = GIMP_DRAWABLE_GET_CLASS (drawable)->get_source_node (drawable);
+
+  gegl_node_add_child (drawable->private->source_node, source);
+
+  g_object_unref (source);
+
+  if (gegl_node_has_pad (source, "input"))
+    {
+      gegl_node_connect_to (input,  "output",
+                            source, "input");
+    }
+
+  filter = gimp_filter_stack_get_graph (GIMP_FILTER_STACK (drawable->private->filter_stack));
+
+  gegl_node_add_child (drawable->private->source_node, filter);
+
+  gegl_node_connect_to (source, "output",
+                        filter, "input");
+
+  output = gegl_node_get_output_proxy (drawable->private->source_node, "output");
+
+  gegl_node_connect_to (filter, "output",
+                        output, "input");
+
+  if (gimp_drawable_get_floating_sel (drawable))
+    _gimp_drawable_add_floating_sel_filter (drawable);
+
+  return drawable->private->source_node;
+}
+
+GeglNode *
+gimp_drawable_get_mode_node (GimpDrawable *drawable)
+{
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
+
+  if (! drawable->private->mode_node)
+    gimp_filter_get_node (GIMP_FILTER (drawable));
+
+  return drawable->private->mode_node;
+}
+
+GeglRectangle
+gimp_drawable_get_bounding_box (GimpDrawable *drawable)
+{
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable),
+                        *GEGL_RECTANGLE (0, 0, 0, 0));
+
+  if (gegl_rectangle_is_empty (&drawable->private->bounding_box))
+    gimp_drawable_update_bounding_box (drawable);
+
+  return drawable->private->bounding_box;
+}
+
+gboolean
+gimp_drawable_update_bounding_box (GimpDrawable *drawable)
+{
+  GeglRectangle bounding_box;
+
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), FALSE);
+
+  bounding_box =
+    GIMP_DRAWABLE_GET_CLASS (drawable)->get_bounding_box (drawable);
+
+  if (! gegl_rectangle_equal (&bounding_box, &drawable->private->bounding_box))
+    {
+      GeglRectangle old_bounding_box = drawable->private->bounding_box;
+      GeglRectangle diff_rects[4];
+      gint          n_diff_rects;
+      gint          i;
+
+      n_diff_rects = gegl_rectangle_subtract (diff_rects,
+                                              &old_bounding_box,
+                                              &bounding_box);
+
+      for (i = 0; i < n_diff_rects; i++)
+        {
+          gimp_drawable_update (drawable,
+                                diff_rects[i].x,
+                                diff_rects[i].y,
+                                diff_rects[i].width,
+                                diff_rects[i].height);
+        }
+
+      drawable->private->bounding_box = bounding_box;
+
+      g_signal_emit (drawable, gimp_drawable_signals[BOUNDING_BOX_CHANGED], 0);
+
+      n_diff_rects = gegl_rectangle_subtract (diff_rects,
+                                              &bounding_box,
+                                              &old_bounding_box);
+
+      for (i = 0; i < n_diff_rects; i++)
+        {
+          gimp_drawable_update (drawable,
+                                diff_rects[i].x,
+                                diff_rects[i].y,
+                                diff_rects[i].width,
+                                diff_rects[i].height);
+        }
+
+      return TRUE;
+    }
+
+  return FALSE;
+}
+
+void
+gimp_drawable_swap_pixels (GimpDrawable *drawable,
+                           GeglBuffer   *buffer,
+                           gint          x,
+                           gint          y)
+{
+  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
+  g_return_if_fail (GEGL_IS_BUFFER (buffer));
+
+  GIMP_DRAWABLE_GET_CLASS (drawable)->swap_pixels (drawable, buffer, x, y);
+}
+
+void
+gimp_drawable_push_undo (GimpDrawable *drawable,
+                         const gchar  *undo_desc,
+                         GeglBuffer   *buffer,
+                         gint          x,
+                         gint          y,
+                         gint          width,
+                         gint          height)
+{
+  GimpItem *item;
+
+  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
+  g_return_if_fail (buffer == NULL || GEGL_IS_BUFFER (buffer));
+
+  item = GIMP_ITEM (drawable);
+
+  g_return_if_fail (gimp_item_is_attached (item));
+
+  if (! buffer &&
+      ! gimp_rectangle_intersect (x, y,
+                                  width, height,
+                                  0, 0,
+                                  gimp_item_get_width (item),
+                                  gimp_item_get_height (item),
+                                  &x, &y, &width, &height))
+    {
+      g_warning ("%s: tried to push empty region", G_STRFUNC);
+      return;
+    }
+
+  GIMP_DRAWABLE_GET_CLASS (drawable)->push_undo (drawable, undo_desc,
+                                                 buffer,
+                                                 x, y, width, height);
+}
+
+const Babl *
+gimp_drawable_get_format (GimpDrawable *drawable)
+{
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
+
+  return gegl_buffer_get_format (drawable->private->buffer);
+}
+
+const Babl *
+gimp_drawable_get_format_with_alpha (GimpDrawable *drawable)
+{
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
+
+  return gimp_image_get_format (gimp_item_get_image (GIMP_ITEM (drawable)),
+                                gimp_drawable_get_base_type (drawable),
+                                gimp_drawable_get_precision (drawable),
+                                TRUE);
+}
+
+const Babl *
+gimp_drawable_get_format_without_alpha (GimpDrawable *drawable)
+{
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
+
+  return gimp_image_get_format (gimp_item_get_image (GIMP_ITEM (drawable)),
+                                gimp_drawable_get_base_type (drawable),
+                                gimp_drawable_get_precision (drawable),
+                                FALSE);
+}
+
+gboolean
+gimp_drawable_get_linear (GimpDrawable *drawable)
+{
+  const Babl *format;
+
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), FALSE);
+
+  format = gegl_buffer_get_format (drawable->private->buffer);
+
+  return gimp_babl_format_get_linear (format);
+}
+
+gboolean
+gimp_drawable_has_alpha (GimpDrawable *drawable)
+{
+  const Babl *format;
+
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), FALSE);
+
+  format = gegl_buffer_get_format (drawable->private->buffer);
+
+  return babl_format_has_alpha (format);
+}
+
+GimpImageBaseType
+gimp_drawable_get_base_type (GimpDrawable *drawable)
+{
+  const Babl *format;
+
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), -1);
+
+  format = gegl_buffer_get_format (drawable->private->buffer);
+
+  return gimp_babl_format_get_base_type (format);
+}
+
+GimpComponentType
+gimp_drawable_get_component_type (GimpDrawable *drawable)
+{
+  const Babl *format;
+
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), -1);
+
+  format = gegl_buffer_get_format (drawable->private->buffer);
+
+  return gimp_babl_format_get_component_type (format);
+}
+
+GimpPrecision
+gimp_drawable_get_precision (GimpDrawable *drawable)
+{
+  const Babl *format;
+
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), -1);
+
+  format = gegl_buffer_get_format (drawable->private->buffer);
+
+  return gimp_babl_format_get_precision (format);
+}
+
+gboolean
+gimp_drawable_is_rgb (GimpDrawable *drawable)
+{
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), FALSE);
+
+  return (gimp_drawable_get_base_type (drawable) == GIMP_RGB);
+}
+
+gboolean
+gimp_drawable_is_gray (GimpDrawable *drawable)
+{
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), FALSE);
+
+  return (gimp_drawable_get_base_type (drawable) == GIMP_GRAY);
+}
+
+gboolean
+gimp_drawable_is_indexed (GimpDrawable *drawable)
+{
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), FALSE);
+
+  return (gimp_drawable_get_base_type (drawable) == GIMP_INDEXED);
+}
+
+const Babl *
+gimp_drawable_get_component_format (GimpDrawable    *drawable,
+                                    GimpChannelType  channel)
+{
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
+
+  switch (channel)
+    {
+    case GIMP_CHANNEL_RED:
+      return gimp_babl_component_format (GIMP_RGB,
+                                         gimp_drawable_get_precision (drawable),
+                                         RED);
+
+    case GIMP_CHANNEL_GREEN:
+      return gimp_babl_component_format (GIMP_RGB,
+                                         gimp_drawable_get_precision (drawable),
+                                         GREEN);
+
+    case GIMP_CHANNEL_BLUE:
+      return gimp_babl_component_format (GIMP_RGB,
+                                         gimp_drawable_get_precision (drawable),
+                                         BLUE);
+
+    case GIMP_CHANNEL_ALPHA:
+      return gimp_babl_component_format (GIMP_RGB,
+                                         gimp_drawable_get_precision (drawable),
+                                         ALPHA);
+
+    case GIMP_CHANNEL_GRAY:
+      return gimp_babl_component_format (GIMP_GRAY,
+                                         gimp_drawable_get_precision (drawable),
+                                         GRAY);
+
+    case GIMP_CHANNEL_INDEXED:
+      return babl_format ("Y u8"); /* will extract grayscale, the best
+                                    * we can do here */
+    }
+
+  return NULL;
+}
+
+gint
+gimp_drawable_get_component_index (GimpDrawable    *drawable,
+                                   GimpChannelType  channel)
+{
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), -1);
+
+  switch (channel)
+    {
+    case GIMP_CHANNEL_RED:     return RED;
+    case GIMP_CHANNEL_GREEN:   return GREEN;
+    case GIMP_CHANNEL_BLUE:    return BLUE;
+    case GIMP_CHANNEL_GRAY:    return GRAY;
+    case GIMP_CHANNEL_INDEXED: return INDEXED;
+    case GIMP_CHANNEL_ALPHA:
+      switch (gimp_drawable_get_base_type (drawable))
+        {
+        case GIMP_RGB:     return ALPHA;
+        case GIMP_GRAY:    return ALPHA_G;
+        case GIMP_INDEXED: return ALPHA_I;
+        }
+    }
+
+  return -1;
+}
+
+const guchar *
+gimp_drawable_get_colormap (GimpDrawable *drawable)
+{
+  GimpImage *image;
+
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
+
+  image = gimp_item_get_image (GIMP_ITEM (drawable));
+
+  return image ? gimp_image_get_colormap (image) : NULL;
+}
+
+void
+gimp_drawable_start_paint (GimpDrawable *drawable)
+{
+  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
+
+  if (drawable->private->paint_count == 0)
+    {
+      GeglBuffer *buffer = gimp_drawable_get_buffer (drawable);
+
+      g_return_if_fail (buffer != NULL);
+      g_return_if_fail (drawable->private->paint_buffer == NULL);
+      g_return_if_fail (drawable->private->paint_copy_region == NULL);
+      g_return_if_fail (drawable->private->paint_update_region == NULL);
+
+      drawable->private->paint_buffer = gimp_gegl_buffer_dup (buffer);
+    }
+
+  drawable->private->paint_count++;
+}
+
+gboolean
+gimp_drawable_end_paint (GimpDrawable *drawable)
+{
+  gboolean result = FALSE;
+
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), FALSE);
+  g_return_val_if_fail (drawable->private->paint_count > 0, FALSE);
+
+  if (drawable->private->paint_count == 1)
+    {
+      result = gimp_drawable_flush_paint (drawable);
+
+      g_clear_object (&drawable->private->paint_buffer);
+    }
+
+  drawable->private->paint_count--;
+
+  return result;
+}
+
+gboolean
+gimp_drawable_flush_paint (GimpDrawable *drawable)
+{
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), FALSE);
+  g_return_val_if_fail (drawable->private->paint_count > 0, FALSE);
+
+  if (drawable->private->paint_copy_region)
+    {
+      GeglBuffer *buffer;
+      gint        n_rects;
+      gint        i;
+
+      buffer = GIMP_DRAWABLE_GET_CLASS (drawable)->get_buffer (drawable);
+
+      g_return_val_if_fail (buffer != NULL, FALSE);
+      g_return_val_if_fail (drawable->private->paint_buffer != NULL, FALSE);
+
+      n_rects = cairo_region_num_rectangles (
+        drawable->private->paint_copy_region);
+
+      for (i = 0; i < n_rects; i++)
+        {
+          GeglRectangle rect;
+
+          cairo_region_get_rectangle (drawable->private->paint_copy_region,
+                                      i, (cairo_rectangle_int_t *) &rect);
+
+          gimp_gegl_buffer_copy (
+            drawable->private->paint_buffer, &rect, GEGL_ABYSS_NONE,
+            buffer, NULL);
+        }
+
+      g_clear_pointer (&drawable->private->paint_copy_region,
+                       cairo_region_destroy);
+
+      n_rects = cairo_region_num_rectangles (
+        drawable->private->paint_update_region);
+
+      for (i = 0; i < n_rects; i++)
+        {
+          GeglRectangle rect;
+
+          cairo_region_get_rectangle (drawable->private->paint_update_region,
+                                      i, (cairo_rectangle_int_t *) &rect);
+
+          g_signal_emit (drawable, gimp_drawable_signals[UPDATE], 0,
+                         rect.x, rect.y, rect.width, rect.height);
+        }
+
+      g_clear_pointer (&drawable->private->paint_update_region,
+                       cairo_region_destroy);
+
+      return TRUE;
+    }
+
+  return FALSE;
+}
+
+gboolean
+gimp_drawable_is_painting (GimpDrawable *drawable)
+{
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), FALSE);
+
+  return drawable->private->paint_count > 0;
+}
diff --git a/app/core/gimpdrawable.h b/app/core/gimpdrawable.h
new file mode 100644
index 0000000..73c4283
--- /dev/null
+++ b/app/core/gimpdrawable.h
@@ -0,0 +1,227 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_DRAWABLE_H__
+#define __GIMP_DRAWABLE_H__
+
+
+#include "gimpitem.h"
+
+
+#define GIMP_TYPE_DRAWABLE            (gimp_drawable_get_type ())
+#define GIMP_DRAWABLE(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_DRAWABLE, GimpDrawable))
+#define GIMP_DRAWABLE_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_DRAWABLE, GimpDrawableClass))
+#define GIMP_IS_DRAWABLE(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_DRAWABLE))
+#define GIMP_IS_DRAWABLE_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_DRAWABLE))
+#define GIMP_DRAWABLE_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_DRAWABLE, GimpDrawableClass))
+
+
+typedef struct _GimpDrawablePrivate GimpDrawablePrivate;
+typedef struct _GimpDrawableClass   GimpDrawableClass;
+
+struct _GimpDrawable
+{
+  GimpItem             parent_instance;
+
+  GimpDrawablePrivate *private;
+};
+
+struct _GimpDrawableClass
+{
+  GimpItemClass  parent_class;
+
+  /*  signals  */
+  void          (* update)                (GimpDrawable         *drawable,
+                                           gint                  x,
+                                           gint                  y,
+                                           gint                  width,
+                                           gint                  height);
+  void          (* format_changed)        (GimpDrawable         *drawable);
+  void          (* alpha_changed)         (GimpDrawable         *drawable);
+  void          (* bounding_box_changed)  (GimpDrawable         *drawable);
+
+  /*  virtual functions  */
+  gint64        (* estimate_memsize)      (GimpDrawable         *drawable,
+                                           GimpComponentType     component_type,
+                                           gint                  width,
+                                           gint                  height);
+  void          (* update_all)            (GimpDrawable         *drawable);
+  void          (* invalidate_boundary)   (GimpDrawable         *drawable);
+  void          (* get_active_components) (GimpDrawable         *drawable,
+                                           gboolean             *active);
+  GimpComponentMask (* get_active_mask)   (GimpDrawable         *drawable);
+  gboolean      (* supports_alpha)        (GimpDrawable         *drawable);
+  void          (* convert_type)          (GimpDrawable         *drawable,
+                                           GimpImage            *dest_image,
+                                           const Babl           *new_format,
+                                           GimpColorProfile     *dest_profile,
+                                           GeglDitherMethod      layer_dither_type,
+                                           GeglDitherMethod      mask_dither_type,
+                                           gboolean              push_undo,
+                                           GimpProgress         *progress);
+  void          (* apply_buffer)          (GimpDrawable         *drawable,
+                                           GeglBuffer           *buffer,
+                                           const GeglRectangle  *buffer_region,
+                                           gboolean              push_undo,
+                                           const gchar          *undo_desc,
+                                           gdouble               opacity,
+                                           GimpLayerMode         mode,
+                                           GimpLayerColorSpace   blend_space,
+                                           GimpLayerColorSpace   composite_space,
+                                           GimpLayerCompositeMode composite_mode,
+                                           GeglBuffer           *base_buffer,
+                                           gint                  base_x,
+                                           gint                  base_y);
+  GeglBuffer  * (* get_buffer)            (GimpDrawable         *drawable);
+  void          (* set_buffer)            (GimpDrawable         *drawable,
+                                           gboolean              push_undo,
+                                           const gchar          *undo_desc,
+                                           GeglBuffer           *buffer,
+                                           const GeglRectangle  *bounds);
+  GeglRectangle (* get_bounding_box)      (GimpDrawable         *drawable);
+  void          (* push_undo)             (GimpDrawable         *drawable,
+                                           const gchar          *undo_desc,
+                                           GeglBuffer           *buffer,
+                                           gint                  x,
+                                           gint                  y,
+                                           gint                  width,
+                                           gint                  height);
+  void          (* swap_pixels)           (GimpDrawable         *drawable,
+                                           GeglBuffer           *buffer,
+                                           gint                  x,
+                                           gint                  y);
+  GeglNode    * (* get_source_node)       (GimpDrawable         *drawable);
+};
+
+
+GType           gimp_drawable_get_type           (void) G_GNUC_CONST;
+
+GimpDrawable  * gimp_drawable_new                (GType               type,
+                                                  GimpImage          *image,
+                                                  const gchar        *name,
+                                                  gint                offset_x,
+                                                  gint                offset_y,
+                                                  gint                width,
+                                                  gint                height,
+                                                  const Babl         *format);
+
+gint64          gimp_drawable_estimate_memsize   (GimpDrawable       *drawable,
+                                                  GimpComponentType   component_type,
+                                                  gint                width,
+                                                  gint                height);
+
+void            gimp_drawable_update             (GimpDrawable       *drawable,
+                                                  gint                x,
+                                                  gint                y,
+                                                  gint                width,
+                                                  gint                height);
+void            gimp_drawable_update_all         (GimpDrawable       *drawable);
+
+void           gimp_drawable_invalidate_boundary (GimpDrawable       *drawable);
+void         gimp_drawable_get_active_components (GimpDrawable       *drawable,
+                                                  gboolean           *active);
+GimpComponentMask gimp_drawable_get_active_mask  (GimpDrawable       *drawable);
+
+gboolean        gimp_drawable_supports_alpha     (GimpDrawable       *drawable);
+
+void            gimp_drawable_convert_type       (GimpDrawable       *drawable,
+                                                  GimpImage          *dest_image,
+                                                  GimpImageBaseType   new_base_type,
+                                                  GimpPrecision       new_precision,
+                                                  gboolean            new_has_alpha,
+                                                  GimpColorProfile   *dest_profile,
+                                                  GeglDitherMethod    layer_dither_type,
+                                                  GeglDitherMethod    mask_dither_type,
+                                                  gboolean            push_undo,
+                                                  GimpProgress       *progress);
+
+void            gimp_drawable_apply_buffer       (GimpDrawable        *drawable,
+                                                  GeglBuffer          *buffer,
+                                                  const GeglRectangle *buffer_rect,
+                                                  gboolean             push_undo,
+                                                  const gchar         *undo_desc,
+                                                  gdouble              opacity,
+                                                  GimpLayerMode        mode,
+                                                  GimpLayerColorSpace  blend_space,
+                                                  GimpLayerColorSpace  composite_space,
+                                                  GimpLayerCompositeMode composite_mode,
+                                                  GeglBuffer          *base_buffer,
+                                                  gint                 base_x,
+                                                  gint                 base_y);
+
+GeglBuffer    * gimp_drawable_get_buffer         (GimpDrawable       *drawable);
+void            gimp_drawable_set_buffer         (GimpDrawable       *drawable,
+                                                  gboolean            push_undo,
+                                                  const gchar        *undo_desc,
+                                                  GeglBuffer         *buffer);
+void            gimp_drawable_set_buffer_full    (GimpDrawable       *drawable,
+                                                  gboolean            push_undo,
+                                                  const gchar        *undo_desc,
+                                                  GeglBuffer         *buffer,
+                                                  const GeglRectangle *bounds,
+                                                  gboolean            update);
+
+void            gimp_drawable_steal_buffer       (GimpDrawable       *drawable,
+                                                  GimpDrawable       *src_drawable);
+
+GeglNode      * gimp_drawable_get_source_node    (GimpDrawable       *drawable);
+GeglNode      * gimp_drawable_get_mode_node      (GimpDrawable       *drawable);
+
+GeglRectangle   gimp_drawable_get_bounding_box   (GimpDrawable       *drawable);
+gboolean        gimp_drawable_update_bounding_box
+                                                 (GimpDrawable       *drawable);
+
+void            gimp_drawable_swap_pixels        (GimpDrawable       *drawable,
+                                                  GeglBuffer         *buffer,
+                                                  gint                x,
+                                                  gint                y);
+
+void            gimp_drawable_push_undo          (GimpDrawable       *drawable,
+                                                  const gchar        *undo_desc,
+                                                  GeglBuffer         *buffer,
+                                                  gint                x,
+                                                  gint                y,
+                                                  gint                width,
+                                                  gint                height);
+
+const Babl      * gimp_drawable_get_format           (GimpDrawable    *drawable);
+const Babl      * gimp_drawable_get_format_with_alpha(GimpDrawable    *drawable);
+const Babl      * gimp_drawable_get_format_without_alpha
+                                                     (GimpDrawable    *drawable);
+gboolean          gimp_drawable_get_linear           (GimpDrawable    *drawable);
+gboolean          gimp_drawable_has_alpha            (GimpDrawable    *drawable);
+GimpImageBaseType gimp_drawable_get_base_type        (GimpDrawable    *drawable);
+GimpComponentType gimp_drawable_get_component_type   (GimpDrawable    *drawable);
+GimpPrecision     gimp_drawable_get_precision        (GimpDrawable    *drawable);
+gboolean          gimp_drawable_is_rgb               (GimpDrawable    *drawable);
+gboolean          gimp_drawable_is_gray              (GimpDrawable    *drawable);
+gboolean          gimp_drawable_is_indexed           (GimpDrawable    *drawable);
+
+const Babl      * gimp_drawable_get_component_format (GimpDrawable    *drawable,
+                                                      GimpChannelType  channel);
+gint              gimp_drawable_get_component_index  (GimpDrawable    *drawable,
+                                                      GimpChannelType  channel);
+
+const guchar    * gimp_drawable_get_colormap         (GimpDrawable    *drawable);
+
+void              gimp_drawable_start_paint          (GimpDrawable    *drawable);
+gboolean          gimp_drawable_end_paint            (GimpDrawable    *drawable);
+gboolean          gimp_drawable_flush_paint          (GimpDrawable    *drawable);
+gboolean          gimp_drawable_is_painting          (GimpDrawable    *drawable);
+
+
+#endif /* __GIMP_DRAWABLE_H__ */
diff --git a/app/core/gimpdrawablefilter.c b/app/core/gimpdrawablefilter.c
new file mode 100644
index 0000000..6cda4f1
--- /dev/null
+++ b/app/core/gimpdrawablefilter.c
@@ -0,0 +1,1364 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/* This file contains the code necessary for generating on canvas
+ * previews, by connecting a specified GEGL operation to do the
+ * processing. It uses drawable filters that allow for non-destructive
+ * manipulation of drawable data, with live preview on screen.
+ *
+ * To create a tool that uses this, see app/tools/gimpfiltertool.c for
+ * the interface and e.g. app/tools/gimpcolorbalancetool.c for an
+ * example of using that interface.
+ */
+
+#include "config.h"
+
+#include <cairo.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpcolor/gimpcolor.h"
+
+#include "core-types.h"
+
+#include "gegl/gimp-babl.h"
+#include "gegl/gimpapplicator.h"
+#include "gegl/gimp-gegl-utils.h"
+
+#include "gimpchannel.h"
+#include "gimpdrawable-filters.h"
+#include "gimpdrawablefilter.h"
+#include "gimpimage.h"
+#include "gimplayer.h"
+#include "gimpmarshal.h"
+#include "gimpprogress.h"
+
+
+enum
+{
+  FLUSH,
+  LAST_SIGNAL
+};
+
+
+struct _GimpDrawableFilter
+{
+  GimpFilter              parent_instance;
+
+  GimpDrawable           *drawable;
+  GeglNode               *operation;
+
+  gboolean                has_input;
+
+  gboolean                clip;
+  GimpFilterRegion        region;
+  gboolean                crop_enabled;
+  GeglRectangle           crop_rect;
+  gboolean                preview_enabled;
+  gboolean                preview_split_enabled;
+  GimpAlignmentType       preview_split_alignment;
+  gint                    preview_split_position;
+  gdouble                 opacity;
+  GimpLayerMode           paint_mode;
+  GimpLayerColorSpace     blend_space;
+  GimpLayerColorSpace     composite_space;
+  GimpLayerCompositeMode  composite_mode;
+  gboolean                add_alpha;
+  gboolean                color_managed;
+  gboolean                gamma_hack;
+
+  gboolean                override_constraints;
+
+  GeglRectangle           filter_area;
+  gboolean                filter_clip;
+
+  GeglNode               *translate;
+  GeglNode               *crop_before;
+  GeglNode               *cast_before;
+  GeglNode               *transform_before;
+  GeglNode               *transform_after;
+  GeglNode               *cast_after;
+  GeglNode               *crop_after;
+  GimpApplicator         *applicator;
+};
+
+
+static void       gimp_drawable_filter_dispose               (GObject             *object);
+static void       gimp_drawable_filter_finalize              (GObject             *object);
+
+static void       gimp_drawable_filter_sync_active           (GimpDrawableFilter  *filter);
+static void       gimp_drawable_filter_sync_clip             (GimpDrawableFilter  *filter,
+                                                              gboolean             sync_region);
+static void       gimp_drawable_filter_sync_region           (GimpDrawableFilter  *filter);
+static void       gimp_drawable_filter_sync_crop             (GimpDrawableFilter  *filter,
+                                                              gboolean             old_crop_enabled,
+                                                              const GeglRectangle *old_crop_rect,
+                                                              gboolean             old_preview_split_enabled,
+                                                              GimpAlignmentType    old_preview_split_alignment,
+                                                              gint                 old_preview_split_position,
+                                                              gboolean             update);
+static void       gimp_drawable_filter_sync_opacity          (GimpDrawableFilter  *filter);
+static void       gimp_drawable_filter_sync_mode             (GimpDrawableFilter  *filter);
+static void       gimp_drawable_filter_sync_affect           (GimpDrawableFilter  *filter);
+static void       gimp_drawable_filter_sync_format           (GimpDrawableFilter  *filter);
+static void       gimp_drawable_filter_sync_mask             (GimpDrawableFilter  *filter);
+static void       gimp_drawable_filter_sync_transform        (GimpDrawableFilter  *filter);
+static void       gimp_drawable_filter_sync_gamma_hack       (GimpDrawableFilter  *filter);
+
+static gboolean   gimp_drawable_filter_is_added              (GimpDrawableFilter  *filter);
+static gboolean   gimp_drawable_filter_is_active             (GimpDrawableFilter  *filter);
+static gboolean   gimp_drawable_filter_add_filter            (GimpDrawableFilter  *filter);
+static gboolean   gimp_drawable_filter_remove_filter         (GimpDrawableFilter  *filter);
+
+static void       gimp_drawable_filter_update_drawable       (GimpDrawableFilter  *filter,
+                                                              const GeglRectangle *area);
+
+static void       gimp_drawable_filter_affect_changed        (GimpImage           *image,
+                                                              GimpChannelType      channel,
+                                                              GimpDrawableFilter  *filter);
+static void       gimp_drawable_filter_mask_changed          (GimpImage           *image,
+                                                              GimpDrawableFilter  *filter);
+static void       gimp_drawable_filter_profile_changed       (GimpColorManaged    *managed,
+                                                              GimpDrawableFilter  *filter);
+static void       gimp_drawable_filter_lock_position_changed (GimpDrawable        *drawable,
+                                                              GimpDrawableFilter  *filter);
+static void       gimp_drawable_filter_format_changed        (GimpDrawable        *drawable,
+                                                              GimpDrawableFilter  *filter);
+static void       gimp_drawable_filter_drawable_removed      (GimpDrawable        *drawable,
+                                                              GimpDrawableFilter  *filter);
+static void       gimp_drawable_filter_lock_alpha_changed    (GimpLayer           *layer,
+                                                              GimpDrawableFilter  *filter);
+
+
+G_DEFINE_TYPE (GimpDrawableFilter, gimp_drawable_filter, GIMP_TYPE_FILTER)
+
+#define parent_class gimp_drawable_filter_parent_class
+
+static guint drawable_filter_signals[LAST_SIGNAL] = { 0, };
+
+
+static void
+gimp_drawable_filter_class_init (GimpDrawableFilterClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  drawable_filter_signals[FLUSH] =
+    g_signal_new ("flush",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpDrawableFilterClass, flush),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  object_class->dispose  = gimp_drawable_filter_dispose;
+  object_class->finalize = gimp_drawable_filter_finalize;
+}
+
+static void
+gimp_drawable_filter_init (GimpDrawableFilter *drawable_filter)
+{
+  drawable_filter->clip                    = TRUE;
+  drawable_filter->region                  = GIMP_FILTER_REGION_SELECTION;
+  drawable_filter->preview_enabled         = TRUE;
+  drawable_filter->preview_split_enabled   = FALSE;
+  drawable_filter->preview_split_alignment = GIMP_ALIGN_LEFT;
+  drawable_filter->preview_split_position  = 0;
+  drawable_filter->opacity                 = GIMP_OPACITY_OPAQUE;
+  drawable_filter->paint_mode              = GIMP_LAYER_MODE_REPLACE;
+  drawable_filter->blend_space             = GIMP_LAYER_COLOR_SPACE_AUTO;
+  drawable_filter->composite_space         = GIMP_LAYER_COLOR_SPACE_AUTO;
+  drawable_filter->composite_mode          = GIMP_LAYER_COMPOSITE_AUTO;
+}
+
+static void
+gimp_drawable_filter_dispose (GObject *object)
+{
+  GimpDrawableFilter *drawable_filter = GIMP_DRAWABLE_FILTER (object);
+
+  if (drawable_filter->drawable)
+    gimp_drawable_filter_remove_filter (drawable_filter);
+
+  G_OBJECT_CLASS (parent_class)->dispose (object);
+}
+
+static void
+gimp_drawable_filter_finalize (GObject *object)
+{
+  GimpDrawableFilter *drawable_filter = GIMP_DRAWABLE_FILTER (object);
+
+  g_clear_object (&drawable_filter->operation);
+  g_clear_object (&drawable_filter->applicator);
+  g_clear_object (&drawable_filter->drawable);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+GimpDrawableFilter *
+gimp_drawable_filter_new (GimpDrawable *drawable,
+                          const gchar  *undo_desc,
+                          GeglNode     *operation,
+                          const gchar  *icon_name)
+{
+  GimpDrawableFilter *filter;
+  GeglNode           *node;
+
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (drawable)), NULL);
+  g_return_val_if_fail (GEGL_IS_NODE (operation), NULL);
+  g_return_val_if_fail (gegl_node_has_pad (operation, "output"), NULL);
+
+  filter = g_object_new (GIMP_TYPE_DRAWABLE_FILTER,
+                         "name",      undo_desc,
+                         "icon-name", icon_name,
+                         NULL);
+
+  filter->drawable  = g_object_ref (drawable);
+  filter->operation = g_object_ref (operation);
+
+  node = gimp_filter_get_node (GIMP_FILTER (filter));
+
+  gegl_node_add_child (node, operation);
+  gimp_gegl_node_set_underlying_operation (node, operation);
+
+  filter->applicator = gimp_applicator_new (node);
+
+  gimp_filter_set_applicator (GIMP_FILTER (filter), filter->applicator);
+
+  gimp_applicator_set_cache (filter->applicator, TRUE);
+
+  filter->has_input = gegl_node_has_pad (filter->operation, "input");
+
+  if (filter->has_input)
+    {
+      GeglNode *input;
+
+      input = gegl_node_get_input_proxy (node, "input");
+
+      filter->translate = gegl_node_new_child (node,
+                                               "operation", "gegl:translate",
+                                               NULL);
+
+      filter->crop_before = gegl_node_new_child (node,
+                                                 "operation", "gegl:crop",
+                                                 NULL);
+
+      filter->cast_before = gegl_node_new_child (node,
+                                                 "operation", "gegl:nop",
+                                                 NULL);
+
+      filter->transform_before = gegl_node_new_child (node,
+                                                      "operation", "gegl:nop",
+                                                      NULL);
+
+      gegl_node_link_many (input,
+                           filter->translate,
+                           filter->crop_before,
+                           filter->cast_before,
+                           filter->transform_before,
+                           filter->operation,
+                           NULL);
+    }
+
+  filter->transform_after = gegl_node_new_child (node,
+                                                 "operation", "gegl:nop",
+                                                 NULL);
+
+  filter->cast_after = gegl_node_new_child (node,
+                                            "operation", "gegl:nop",
+                                            NULL);
+
+  filter->crop_after = gegl_node_new_child (node,
+                                            "operation", "gegl:crop",
+                                            NULL);
+
+  gegl_node_link_many (filter->operation,
+                       filter->transform_after,
+                       filter->cast_after,
+                       filter->crop_after,
+                       NULL);
+
+  gegl_node_connect_to (filter->crop_after, "output",
+                        node,               "aux");
+
+  return filter;
+}
+
+GimpDrawable *
+gimp_drawable_filter_get_drawable (GimpDrawableFilter *filter)
+{
+  g_return_val_if_fail (GIMP_IS_DRAWABLE_FILTER (filter), NULL);
+
+  return filter->drawable;
+}
+
+GeglNode *
+gimp_drawable_filter_get_operation (GimpDrawableFilter *filter)
+{
+  g_return_val_if_fail (GIMP_IS_DRAWABLE_FILTER (filter), NULL);
+
+  return filter->operation;
+}
+
+void
+gimp_drawable_filter_set_clip (GimpDrawableFilter *filter,
+                               gboolean            clip)
+{
+  g_return_if_fail (GIMP_IS_DRAWABLE_FILTER (filter));
+
+  if (clip != filter->clip)
+    {
+      filter->clip = clip;
+
+      gimp_drawable_filter_sync_clip (filter, TRUE);
+    }
+}
+
+void
+gimp_drawable_filter_set_region (GimpDrawableFilter *filter,
+                                 GimpFilterRegion    region)
+{
+  g_return_if_fail (GIMP_IS_DRAWABLE_FILTER (filter));
+
+  if (region != filter->region)
+    {
+      filter->region = region;
+
+      gimp_drawable_filter_sync_region (filter);
+
+      if (gimp_drawable_filter_is_active (filter))
+        gimp_drawable_filter_update_drawable (filter, NULL);
+    }
+}
+
+void
+gimp_drawable_filter_set_crop (GimpDrawableFilter  *filter,
+                               const GeglRectangle *rect,
+                               gboolean             update)
+{
+  g_return_if_fail (GIMP_IS_DRAWABLE_FILTER (filter));
+
+  if ((rect != NULL) != filter->crop_enabled ||
+      (rect && ! gegl_rectangle_equal (rect, &filter->crop_rect)))
+    {
+      gboolean      old_enabled = filter->crop_enabled;
+      GeglRectangle old_rect    = filter->crop_rect;
+
+      if (rect)
+        {
+          filter->crop_enabled = TRUE;
+          filter->crop_rect    = *rect;
+        }
+      else
+        {
+          filter->crop_enabled = FALSE;
+        }
+
+      gimp_drawable_filter_sync_crop (filter,
+                                      old_enabled,
+                                      &old_rect,
+                                      filter->preview_split_enabled,
+                                      filter->preview_split_alignment,
+                                      filter->preview_split_position,
+                                      update);
+    }
+}
+
+void
+gimp_drawable_filter_set_preview (GimpDrawableFilter *filter,
+                                  gboolean            enabled)
+{
+  g_return_if_fail (GIMP_IS_DRAWABLE_FILTER (filter));
+
+  if (enabled != filter->preview_enabled)
+    {
+      filter->preview_enabled = enabled;
+
+      gimp_drawable_filter_sync_active (filter);
+
+      if (gimp_drawable_filter_is_added (filter))
+        {
+          gimp_drawable_update_bounding_box (filter->drawable);
+
+          gimp_drawable_filter_update_drawable (filter, NULL);
+        }
+    }
+}
+
+void
+gimp_drawable_filter_set_preview_split (GimpDrawableFilter  *filter,
+                                        gboolean             enabled,
+                                        GimpAlignmentType    alignment,
+                                        gint                 position)
+{
+  GimpItem *item;
+
+  g_return_if_fail (GIMP_IS_DRAWABLE_FILTER (filter));
+  g_return_if_fail (alignment == GIMP_ALIGN_LEFT  ||
+                    alignment == GIMP_ALIGN_RIGHT ||
+                    alignment == GIMP_ALIGN_TOP   ||
+                    alignment == GIMP_ALIGN_BOTTOM);
+
+  item = GIMP_ITEM (filter->drawable);
+
+  switch (alignment)
+    {
+    case GIMP_ALIGN_LEFT:
+    case GIMP_ALIGN_RIGHT:
+      position = CLAMP (position, 0, gimp_item_get_width (item));
+      break;
+
+    case GIMP_ALIGN_TOP:
+    case GIMP_ALIGN_BOTTOM:
+      position = CLAMP (position, 0, gimp_item_get_height (item));
+      break;
+
+    default:
+      g_return_if_reached ();
+    }
+
+  if (enabled   != filter->preview_split_enabled   ||
+      alignment != filter->preview_split_alignment ||
+      position  != filter->preview_split_position)
+    {
+      gboolean          old_enabled   = filter->preview_split_enabled;
+      GimpAlignmentType old_alignment = filter->preview_split_alignment;
+      gint              old_position  = filter->preview_split_position;
+
+      filter->preview_split_enabled   = enabled;
+      filter->preview_split_alignment = alignment;
+      filter->preview_split_position  = position;
+
+      gimp_drawable_filter_sync_crop (filter,
+                                      filter->crop_enabled,
+                                      &filter->crop_rect,
+                                      old_enabled,
+                                      old_alignment,
+                                      old_position,
+                                      TRUE);
+    }
+}
+
+void
+gimp_drawable_filter_set_opacity (GimpDrawableFilter *filter,
+                                  gdouble             opacity)
+{
+  g_return_if_fail (GIMP_IS_DRAWABLE_FILTER (filter));
+
+  if (opacity != filter->opacity)
+    {
+      filter->opacity = opacity;
+
+      gimp_drawable_filter_sync_opacity (filter);
+
+      if (gimp_drawable_filter_is_active (filter))
+        gimp_drawable_filter_update_drawable (filter, NULL);
+    }
+}
+
+void
+gimp_drawable_filter_set_mode (GimpDrawableFilter     *filter,
+                               GimpLayerMode           paint_mode,
+                               GimpLayerColorSpace     blend_space,
+                               GimpLayerColorSpace     composite_space,
+                               GimpLayerCompositeMode  composite_mode)
+{
+  g_return_if_fail (GIMP_IS_DRAWABLE_FILTER (filter));
+
+  if (paint_mode      != filter->paint_mode      ||
+      blend_space     != filter->blend_space     ||
+      composite_space != filter->composite_space ||
+      composite_mode  != filter->composite_mode)
+    {
+      filter->paint_mode      = paint_mode;
+      filter->blend_space     = blend_space;
+      filter->composite_space = composite_space;
+      filter->composite_mode  = composite_mode;
+
+      gimp_drawable_filter_sync_mode (filter);
+
+      if (gimp_drawable_filter_is_active (filter))
+        gimp_drawable_filter_update_drawable (filter, NULL);
+    }
+}
+
+void
+gimp_drawable_filter_set_add_alpha (GimpDrawableFilter *filter,
+                                    gboolean            add_alpha)
+{
+  g_return_if_fail (GIMP_IS_DRAWABLE_FILTER (filter));
+
+  if (add_alpha != filter->add_alpha)
+    {
+      filter->add_alpha = add_alpha;
+
+      gimp_drawable_filter_sync_format (filter);
+
+      if (gimp_drawable_filter_is_active (filter))
+        gimp_drawable_filter_update_drawable (filter, NULL);
+    }
+}
+
+void
+gimp_drawable_filter_set_color_managed (GimpDrawableFilter *filter,
+                                        gboolean            color_managed)
+{
+  g_return_if_fail (GIMP_IS_DRAWABLE_FILTER (filter));
+
+  if (color_managed != filter->color_managed)
+    {
+      filter->color_managed = color_managed;
+
+      gimp_drawable_filter_sync_transform (filter);
+
+      if (gimp_drawable_filter_is_active (filter))
+        gimp_drawable_filter_update_drawable (filter, NULL);
+    }
+}
+
+void
+gimp_drawable_filter_set_gamma_hack (GimpDrawableFilter *filter,
+                                     gboolean            gamma_hack)
+{
+  g_return_if_fail (GIMP_IS_DRAWABLE_FILTER (filter));
+
+  if (gamma_hack != filter->gamma_hack)
+    {
+      filter->gamma_hack = gamma_hack;
+
+      gimp_drawable_filter_sync_gamma_hack (filter);
+      gimp_drawable_filter_sync_transform (filter);
+
+      if (gimp_drawable_filter_is_active (filter))
+        gimp_drawable_filter_update_drawable (filter, NULL);
+    }
+}
+
+void
+gimp_drawable_filter_set_override_constraints (GimpDrawableFilter *filter,
+                                               gboolean            override_constraints)
+{
+  g_return_if_fail (GIMP_IS_DRAWABLE_FILTER (filter));
+
+  if (override_constraints != filter->override_constraints)
+    {
+      filter->override_constraints = override_constraints;
+
+      gimp_drawable_filter_sync_affect (filter);
+      gimp_drawable_filter_sync_format (filter);
+      gimp_drawable_filter_sync_clip   (filter, TRUE);
+
+      if (gimp_drawable_filter_is_active (filter))
+        gimp_drawable_filter_update_drawable (filter, NULL);
+    }
+}
+
+const Babl *
+gimp_drawable_filter_get_format (GimpDrawableFilter *filter)
+{
+  const Babl *format;
+
+  g_return_val_if_fail (GIMP_IS_DRAWABLE_FILTER (filter), NULL);
+
+  format = gimp_applicator_get_output_format (filter->applicator);
+
+  if (! format)
+    format = gimp_drawable_get_format (filter->drawable);
+
+  return format;
+}
+
+void
+gimp_drawable_filter_apply (GimpDrawableFilter  *filter,
+                            const GeglRectangle *area)
+{
+  g_return_if_fail (GIMP_IS_DRAWABLE_FILTER (filter));
+  g_return_if_fail (gimp_item_is_attached (GIMP_ITEM (filter->drawable)));
+
+  gimp_drawable_filter_add_filter (filter);
+
+  gimp_drawable_filter_sync_clip (filter, TRUE);
+
+  if (gimp_drawable_filter_is_active (filter))
+    {
+      gimp_drawable_update_bounding_box (filter->drawable);
+
+      gimp_drawable_filter_update_drawable (filter, area);
+    }
+}
+
+gboolean
+gimp_drawable_filter_commit (GimpDrawableFilter *filter,
+                             GimpProgress       *progress,
+                             gboolean            cancellable)
+{
+  gboolean success = TRUE;
+
+  g_return_val_if_fail (GIMP_IS_DRAWABLE_FILTER (filter), FALSE);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (filter->drawable)),
+                        FALSE);
+  g_return_val_if_fail (progress == NULL || GIMP_IS_PROGRESS (progress), FALSE);
+
+  if (gimp_drawable_filter_is_added (filter))
+    {
+      const Babl *format;
+
+      format = gimp_drawable_filter_get_format (filter);
+
+      gimp_drawable_filter_set_preview_split (filter, FALSE,
+                                              filter->preview_split_alignment,
+                                              filter->preview_split_position);
+      gimp_drawable_filter_set_preview (filter, TRUE);
+
+      success = gimp_drawable_merge_filter (filter->drawable,
+                                            GIMP_FILTER (filter),
+                                            progress,
+                                            gimp_object_get_name (filter),
+                                            format,
+                                            filter->filter_clip,
+                                            cancellable,
+                                            FALSE);
+
+      gimp_drawable_filter_remove_filter (filter);
+
+      if (! success)
+        gimp_drawable_filter_update_drawable (filter, NULL);
+
+      g_signal_emit (filter, drawable_filter_signals[FLUSH], 0);
+    }
+
+  return success;
+}
+
+void
+gimp_drawable_filter_abort (GimpDrawableFilter *filter)
+{
+  g_return_if_fail (GIMP_IS_DRAWABLE_FILTER (filter));
+
+  if (gimp_drawable_filter_remove_filter (filter))
+    {
+      gimp_drawable_filter_update_drawable (filter, NULL);
+    }
+}
+
+
+/*  private functions  */
+
+static void
+gimp_drawable_filter_sync_active (GimpDrawableFilter *filter)
+{
+  gimp_applicator_set_active (filter->applicator, filter->preview_enabled);
+}
+
+static void
+gimp_drawable_filter_sync_clip (GimpDrawableFilter *filter,
+                                gboolean            sync_region)
+{
+  gboolean clip;
+
+  if (filter->override_constraints)
+    clip = filter->clip;
+  else
+    clip = gimp_item_get_clip (GIMP_ITEM (filter->drawable), filter->clip);
+
+  if (! clip)
+    {
+      GimpImage   *image = gimp_item_get_image (GIMP_ITEM (filter->drawable));
+      GimpChannel *mask  = gimp_image_get_mask (image);
+
+      if (! gimp_channel_is_empty (mask))
+        clip = TRUE;
+    }
+
+  if (! clip)
+    {
+      GeglRectangle bounding_box;
+
+      bounding_box = gegl_node_get_bounding_box (filter->operation);
+
+      if (gegl_rectangle_is_infinite_plane (&bounding_box))
+        clip = TRUE;
+    }
+
+  if (clip != filter->filter_clip)
+    {
+      filter->filter_clip = clip;
+
+      if (sync_region)
+        gimp_drawable_filter_sync_region (filter);
+    }
+}
+
+static void
+gimp_drawable_filter_sync_region (GimpDrawableFilter *filter)
+{
+  if (filter->region == GIMP_FILTER_REGION_SELECTION)
+    {
+      if (filter->has_input)
+        {
+          gegl_node_set (filter->translate,
+                         "x", (gdouble) -filter->filter_area.x,
+                         "y", (gdouble) -filter->filter_area.y,
+                         NULL);
+
+          gegl_node_set (filter->crop_before,
+                         "width",  (gdouble) filter->filter_area.width,
+                         "height", (gdouble) filter->filter_area.height,
+                         NULL);
+        }
+
+      if (filter->filter_clip)
+        {
+          gegl_node_set (filter->crop_after,
+                         "operation", "gegl:crop",
+                         "x",         0.0,
+                         "y",         0.0,
+                         "width",     (gdouble) filter->filter_area.width,
+                         "height",    (gdouble) filter->filter_area.height,
+                         NULL);
+        }
+      else
+        {
+          gegl_node_set (filter->crop_after,
+                         "operation", "gegl:nop",
+                         NULL);
+        }
+
+      gimp_applicator_set_apply_offset (filter->applicator,
+                                        filter->filter_area.x,
+                                        filter->filter_area.y);
+    }
+  else
+    {
+      GimpItem *item   = GIMP_ITEM (filter->drawable);
+      gdouble   width  = gimp_item_get_width (item);
+      gdouble   height = gimp_item_get_height (item);
+
+      if (filter->has_input)
+        {
+          gegl_node_set (filter->translate,
+                         "x", (gdouble) 0.0,
+                         "y", (gdouble) 0.0,
+                         NULL);
+
+          gegl_node_set (filter->crop_before,
+                         "width",  width,
+                         "height", height,
+                         NULL);
+        }
+
+      if (filter->filter_clip)
+        {
+          gegl_node_set (filter->crop_after,
+                         "operation", "gegl:crop",
+                         "x",         (gdouble) filter->filter_area.x,
+                         "y",         (gdouble) filter->filter_area.y,
+                         "width",     (gdouble) filter->filter_area.width,
+                         "height",    (gdouble) filter->filter_area.height,
+                         NULL);
+        }
+      else
+        {
+          gegl_node_set (filter->crop_after,
+                         "operation", "gegl:nop",
+                         NULL);
+        }
+
+      gimp_applicator_set_apply_offset (filter->applicator, 0, 0);
+    }
+
+  if (gimp_drawable_filter_is_active (filter))
+    {
+      if (gimp_drawable_update_bounding_box (filter->drawable))
+        g_signal_emit (filter, drawable_filter_signals[FLUSH], 0);
+    }
+}
+
+static gboolean
+gimp_drawable_filter_get_crop_rect (GimpDrawableFilter  *filter,
+                                    gboolean             crop_enabled,
+                                    const GeglRectangle *crop_rect,
+                                    gboolean             preview_split_enabled,
+                                    GimpAlignmentType    preview_split_alignment,
+                                    gint                 preview_split_position,
+                                    GeglRectangle       *rect)
+{
+  GeglRectangle bounds;
+  gint          x1, x2;
+  gint          y1, y2;
+
+  bounds = gegl_rectangle_infinite_plane ();
+
+  x1 = bounds.x;
+  x2 = bounds.x + bounds.width;
+
+  y1 = bounds.y;
+  y2 = bounds.y + bounds.height;
+
+  if (preview_split_enabled)
+    {
+      switch (preview_split_alignment)
+        {
+        case GIMP_ALIGN_LEFT:
+          x2 = preview_split_position;
+          break;
+
+        case GIMP_ALIGN_RIGHT:
+          x1 = preview_split_position;
+          break;
+
+        case GIMP_ALIGN_TOP:
+          y2 = preview_split_position;
+          break;
+
+        case GIMP_ALIGN_BOTTOM:
+          y1 = preview_split_position;
+          break;
+
+        default:
+          g_return_val_if_reached (FALSE);
+        }
+    }
+
+  gegl_rectangle_set (rect, x1, y1, x2 - x1, y2 - y1);
+
+  if (crop_enabled)
+    gegl_rectangle_intersect (rect, rect, crop_rect);
+
+  return ! gegl_rectangle_equal (rect, &bounds);
+}
+
+static void
+gimp_drawable_filter_sync_crop (GimpDrawableFilter  *filter,
+                                gboolean             old_crop_enabled,
+                                const GeglRectangle *old_crop_rect,
+                                gboolean             old_preview_split_enabled,
+                                GimpAlignmentType    old_preview_split_alignment,
+                                gint                 old_preview_split_position,
+                                gboolean             update)
+{
+  GeglRectangle old_rect;
+  GeglRectangle new_rect;
+  gboolean      enabled;
+
+  gimp_drawable_filter_get_crop_rect (filter,
+                                      old_crop_enabled,
+                                      old_crop_rect,
+                                      old_preview_split_enabled,
+                                      old_preview_split_alignment,
+                                      old_preview_split_position,
+                                      &old_rect);
+
+  enabled = gimp_drawable_filter_get_crop_rect (filter,
+                                                filter->crop_enabled,
+                                                &filter->crop_rect,
+                                                filter->preview_split_enabled,
+                                                filter->preview_split_alignment,
+                                                filter->preview_split_position,
+                                                &new_rect);
+
+  gimp_applicator_set_crop (filter->applicator, enabled ? &new_rect : NULL);
+
+  if (update                                     &&
+      gimp_drawable_filter_is_active (filter) &&
+      ! gegl_rectangle_equal (&old_rect, &new_rect))
+    {
+      GeglRectangle diff_rects[4];
+      gint          n_diff_rects;
+      gint          i;
+
+      gimp_drawable_update_bounding_box (filter->drawable);
+
+      n_diff_rects = gegl_rectangle_xor (diff_rects, &old_rect, &new_rect);
+
+      for (i = 0; i < n_diff_rects; i++)
+        gimp_drawable_filter_update_drawable (filter, &diff_rects[i]);
+    }
+}
+
+static void
+gimp_drawable_filter_sync_opacity (GimpDrawableFilter *filter)
+{
+  gimp_applicator_set_opacity (filter->applicator,
+                               filter->opacity);
+}
+
+static void
+gimp_drawable_filter_sync_mode (GimpDrawableFilter *filter)
+{
+  GimpLayerMode paint_mode = filter->paint_mode;
+
+  if (! filter->has_input && paint_mode == GIMP_LAYER_MODE_REPLACE)
+    {
+      /* if the filter's op has no input, use NORMAL instead of REPLACE, so
+       * that we composite the op's output on top of the input, instead of
+       * completely replacing it.
+       */
+      paint_mode = GIMP_LAYER_MODE_NORMAL;
+    }
+
+  gimp_applicator_set_mode (filter->applicator,
+                            paint_mode,
+                            filter->blend_space,
+                            filter->composite_space,
+                            filter->composite_mode);
+}
+
+static void
+gimp_drawable_filter_sync_affect (GimpDrawableFilter *filter)
+{
+  gimp_applicator_set_affect (
+    filter->applicator,
+    filter->override_constraints ?
+
+      GIMP_COMPONENT_MASK_RED   |
+      GIMP_COMPONENT_MASK_GREEN |
+      GIMP_COMPONENT_MASK_BLUE  |
+      GIMP_COMPONENT_MASK_ALPHA :
+
+      gimp_drawable_get_active_mask (filter->drawable));
+}
+
+static void
+gimp_drawable_filter_sync_format (GimpDrawableFilter *filter)
+{
+  const Babl *format;
+
+  if (filter->add_alpha                                &&
+      (gimp_drawable_supports_alpha (filter->drawable) ||
+       filter->override_constraints))
+    {
+      format = gimp_drawable_get_format_with_alpha (filter->drawable);
+    }
+  else
+    {
+      format = gimp_drawable_get_format (filter->drawable);
+    }
+
+  gimp_applicator_set_output_format (filter->applicator, format);
+}
+
+static void
+gimp_drawable_filter_sync_mask (GimpDrawableFilter *filter)
+{
+  GimpImage   *image = gimp_item_get_image (GIMP_ITEM (filter->drawable));
+  GimpChannel *mask  = gimp_image_get_mask (image);
+
+  if (gimp_channel_is_empty (mask))
+    {
+      gimp_applicator_set_mask_buffer (filter->applicator, NULL);
+    }
+  else
+    {
+      GeglBuffer *mask_buffer;
+      gint        offset_x, offset_y;
+
+      mask_buffer = gimp_drawable_get_buffer (GIMP_DRAWABLE (mask));
+      gimp_item_get_offset (GIMP_ITEM (filter->drawable),
+                            &offset_x, &offset_y);
+
+      gimp_applicator_set_mask_buffer (filter->applicator, mask_buffer);
+      gimp_applicator_set_mask_offset (filter->applicator,
+                                       -offset_x, -offset_y);
+    }
+
+  gimp_item_mask_intersect (GIMP_ITEM (filter->drawable),
+                            &filter->filter_area.x,
+                            &filter->filter_area.y,
+                            &filter->filter_area.width,
+                            &filter->filter_area.height);
+}
+
+static void
+gimp_drawable_filter_sync_transform (GimpDrawableFilter *filter)
+{
+  GimpColorManaged *managed = GIMP_COLOR_MANAGED (filter->drawable);
+
+  if (filter->color_managed)
+    {
+      const Babl       *drawable_format  = NULL;
+      const Babl       *input_format     = NULL;
+      const Babl       *output_format    = NULL;
+      GimpColorProfile *drawable_profile = NULL;
+      GimpColorProfile *input_profile    = NULL;
+      GimpColorProfile *output_profile   = NULL;
+      guint32           dummy;
+
+      drawable_format = gimp_drawable_get_format (filter->drawable);
+      if (filter->has_input)
+        input_format  = gimp_gegl_node_get_format (filter->operation, "input");
+      output_format   = gimp_gegl_node_get_format (filter->operation, "output");
+
+      g_printerr ("drawable format:      %s\n", babl_get_name (drawable_format));
+      if (filter->has_input)
+        g_printerr ("filter input format:  %s\n", babl_get_name (input_format));
+      g_printerr ("filter output format: %s\n", babl_get_name (output_format));
+
+      /*  convert the drawable format to float, so we get a precise
+       *  color transform
+       */
+      drawable_format =
+        gimp_babl_format (gimp_babl_format_get_base_type (drawable_format),
+                          gimp_babl_precision (GIMP_COMPONENT_TYPE_FLOAT,
+                                               gimp_babl_format_get_linear (drawable_format)),
+                          babl_format_has_alpha (drawable_format));
+
+      /*  convert the filter input/output formats to something we have
+       *  built-in color profiles for (see the get_color_profile()
+       *  calls below)
+       */
+      if (filter->has_input)
+        input_format = gimp_color_profile_get_lcms_format (input_format,  &dummy);
+      output_format  = gimp_color_profile_get_lcms_format (output_format, &dummy);
+
+      g_printerr ("profile transform drawable format: %s\n",
+                  babl_get_name (drawable_format));
+      if (filter->has_input)
+        g_printerr ("profile transform input format:    %s\n",
+                    babl_get_name (input_format));
+      g_printerr ("profile transform output format:   %s\n",
+                  babl_get_name (output_format));
+
+      drawable_profile = gimp_color_managed_get_color_profile (managed);
+      if (filter->has_input)
+        input_profile  = gimp_babl_format_get_color_profile (input_format);
+      output_profile   = gimp_babl_format_get_color_profile (output_format);
+
+      if ((filter->has_input &&
+           ! gimp_color_transform_can_gegl_copy (drawable_profile,
+                                                 input_profile)) ||
+          ! gimp_color_transform_can_gegl_copy (output_profile,
+                                                drawable_profile))
+        {
+          g_printerr ("using gimp:profile-transform\n");
+
+          if (filter->has_input)
+            {
+              gegl_node_set (filter->transform_before,
+                             "operation",    "gimp:profile-transform",
+                             "src-profile",  drawable_profile,
+                             "src-format",   drawable_format,
+                             "dest-profile", input_profile,
+                             "dest-format",  input_format,
+                             NULL);
+            }
+
+          gegl_node_set (filter->transform_after,
+                         "operation",    "gimp:profile-transform",
+                         "src-profile",  output_profile,
+                         "src-format",   output_format,
+                         "dest-profile", drawable_profile,
+                         "dest-format",  drawable_format,
+                         NULL);
+
+          return;
+        }
+    }
+
+  g_printerr ("using gegl copy\n");
+
+  if (filter->has_input)
+    {
+      gegl_node_set (filter->transform_before,
+                     "operation", "gegl:nop",
+                     NULL);
+    }
+
+  gegl_node_set (filter->transform_after,
+                 "operation", "gegl:nop",
+                 NULL);
+}
+
+static void
+gimp_drawable_filter_sync_gamma_hack (GimpDrawableFilter *filter)
+{
+  if (filter->gamma_hack)
+    {
+      const Babl *drawable_format;
+      const Babl *cast_format;
+
+      drawable_format =
+        gimp_drawable_get_format_with_alpha (filter->drawable);
+
+      cast_format =
+        gimp_babl_format (gimp_babl_format_get_base_type (drawable_format),
+                          gimp_babl_precision (gimp_babl_format_get_component_type (drawable_format),
+                                               ! gimp_babl_format_get_linear (drawable_format)),
+                          TRUE);
+
+      if (filter->has_input)
+        {
+          gegl_node_set (filter->cast_before,
+                         "operation",     "gegl:cast-format",
+                         "input-format",  drawable_format,
+                         "output-format", cast_format,
+                         NULL);
+        }
+
+      gegl_node_set (filter->cast_after,
+                     "operation",     "gegl:cast-format",
+                     "input-format",  cast_format,
+                     "output-format", drawable_format,
+                     NULL);
+    }
+  else
+    {
+      if (filter->has_input)
+        {
+          gegl_node_set (filter->cast_before,
+                         "operation", "gegl:nop",
+                         NULL);
+        }
+
+      gegl_node_set (filter->cast_after,
+                     "operation", "gegl:nop",
+                     NULL);
+    }
+}
+
+static gboolean
+gimp_drawable_filter_is_added (GimpDrawableFilter *filter)
+{
+  return gimp_drawable_has_filter (filter->drawable,
+                                   GIMP_FILTER (filter));
+}
+
+static gboolean
+gimp_drawable_filter_is_active (GimpDrawableFilter *filter)
+{
+  return gimp_drawable_filter_is_added (filter) &&
+         filter->preview_enabled;
+}
+
+static gboolean
+gimp_drawable_filter_add_filter (GimpDrawableFilter *filter)
+{
+  if (! gimp_drawable_filter_is_added (filter))
+    {
+      GimpImage *image = gimp_item_get_image (GIMP_ITEM (filter->drawable));
+
+      gimp_viewable_preview_freeze (GIMP_VIEWABLE (filter->drawable));
+
+      gimp_drawable_filter_sync_active (filter);
+      gimp_drawable_filter_sync_mask (filter);
+      gimp_drawable_filter_sync_clip (filter, FALSE);
+      gimp_drawable_filter_sync_region (filter);
+      gimp_drawable_filter_sync_crop (filter,
+                                      filter->crop_enabled,
+                                      &filter->crop_rect,
+                                      filter->preview_split_enabled,
+                                      filter->preview_split_alignment,
+                                      filter->preview_split_position,
+                                      TRUE);
+      gimp_drawable_filter_sync_opacity (filter);
+      gimp_drawable_filter_sync_mode (filter);
+      gimp_drawable_filter_sync_affect (filter);
+      gimp_drawable_filter_sync_format (filter);
+      gimp_drawable_filter_sync_transform (filter);
+      gimp_drawable_filter_sync_gamma_hack (filter);
+
+      gimp_drawable_add_filter (filter->drawable,
+                                GIMP_FILTER (filter));
+
+      gimp_drawable_update_bounding_box (filter->drawable);
+
+      g_signal_connect (image, "component-active-changed",
+                        G_CALLBACK (gimp_drawable_filter_affect_changed),
+                        filter);
+      g_signal_connect (image, "mask-changed",
+                        G_CALLBACK (gimp_drawable_filter_mask_changed),
+                        filter);
+      g_signal_connect (image, "profile-changed",
+                        G_CALLBACK (gimp_drawable_filter_profile_changed),
+                        filter);
+      g_signal_connect (filter->drawable, "lock-position-changed",
+                        G_CALLBACK (gimp_drawable_filter_lock_position_changed),
+                        filter);
+      g_signal_connect (filter->drawable, "format-changed",
+                        G_CALLBACK (gimp_drawable_filter_format_changed),
+                        filter);
+      g_signal_connect (filter->drawable, "removed",
+                        G_CALLBACK (gimp_drawable_filter_drawable_removed),
+                        filter);
+
+      if (GIMP_IS_LAYER (filter->drawable))
+        {
+          g_signal_connect (filter->drawable, "lock-alpha-changed",
+                            G_CALLBACK (gimp_drawable_filter_lock_alpha_changed),
+                            filter);
+        }
+
+      return TRUE;
+    }
+
+  return FALSE;
+}
+
+static gboolean
+gimp_drawable_filter_remove_filter (GimpDrawableFilter *filter)
+{
+  if (gimp_drawable_filter_is_added (filter))
+    {
+      GimpImage *image = gimp_item_get_image (GIMP_ITEM (filter->drawable));
+
+      if (GIMP_IS_LAYER (filter->drawable))
+        {
+          g_signal_handlers_disconnect_by_func (filter->drawable,
+                                                gimp_drawable_filter_lock_alpha_changed,
+                                                filter);
+        }
+
+      g_signal_handlers_disconnect_by_func (filter->drawable,
+                                            gimp_drawable_filter_drawable_removed,
+                                            filter);
+      g_signal_handlers_disconnect_by_func (filter->drawable,
+                                            gimp_drawable_filter_format_changed,
+                                            filter);
+      g_signal_handlers_disconnect_by_func (filter->drawable,
+                                            gimp_drawable_filter_lock_position_changed,
+                                            filter);
+      g_signal_handlers_disconnect_by_func (image,
+                                            gimp_drawable_filter_profile_changed,
+                                            filter);
+      g_signal_handlers_disconnect_by_func (image,
+                                            gimp_drawable_filter_mask_changed,
+                                            filter);
+      g_signal_handlers_disconnect_by_func (image,
+                                            gimp_drawable_filter_affect_changed,
+                                            filter);
+
+      gimp_drawable_remove_filter (filter->drawable,
+                                   GIMP_FILTER (filter));
+
+      gimp_drawable_update_bounding_box (filter->drawable);
+
+      gimp_viewable_preview_thaw (GIMP_VIEWABLE (filter->drawable));
+
+      return TRUE;
+    }
+
+  return FALSE;
+}
+
+static void
+gimp_drawable_filter_update_drawable (GimpDrawableFilter  *filter,
+                                      const GeglRectangle *area)
+{
+  GeglRectangle bounding_box;
+  GeglRectangle update_area;
+
+  bounding_box = gimp_drawable_get_bounding_box (filter->drawable);
+
+  if (area)
+    {
+      if (! gegl_rectangle_intersect (&update_area,
+                                      area, &bounding_box))
+        {
+          return;
+        }
+    }
+  else
+    {
+      gimp_drawable_filter_get_crop_rect (filter,
+                                          filter->crop_enabled,
+                                          &filter->crop_rect,
+                                          filter->preview_split_enabled,
+                                          filter->preview_split_alignment,
+                                          filter->preview_split_position,
+                                          &update_area);
+
+      if (! gegl_rectangle_intersect (&update_area,
+                                      &update_area, &bounding_box))
+        {
+          return;
+        }
+    }
+
+  if (update_area.width  > 0 &&
+      update_area.height > 0)
+    {
+      gimp_drawable_update (filter->drawable,
+                            update_area.x,
+                            update_area.y,
+                            update_area.width,
+                            update_area.height);
+
+      g_signal_emit (filter, drawable_filter_signals[FLUSH], 0);
+    }
+}
+
+static void
+gimp_drawable_filter_affect_changed (GimpImage          *image,
+                                     GimpChannelType     channel,
+                                     GimpDrawableFilter *filter)
+{
+  gimp_drawable_filter_sync_affect (filter);
+  gimp_drawable_filter_update_drawable (filter, NULL);
+}
+
+static void
+gimp_drawable_filter_mask_changed (GimpImage          *image,
+                                   GimpDrawableFilter *filter)
+{
+  gimp_drawable_filter_update_drawable (filter, NULL);
+
+  gimp_drawable_filter_sync_mask (filter);
+  gimp_drawable_filter_sync_clip (filter, FALSE);
+  gimp_drawable_filter_sync_region (filter);
+
+  gimp_drawable_filter_update_drawable (filter, NULL);
+}
+
+static void
+gimp_drawable_filter_profile_changed (GimpColorManaged   *managed,
+                                      GimpDrawableFilter *filter)
+{
+  gimp_drawable_filter_sync_transform (filter);
+  gimp_drawable_filter_update_drawable (filter, NULL);
+}
+
+static void
+gimp_drawable_filter_lock_position_changed (GimpDrawable       *drawable,
+                                            GimpDrawableFilter *filter)
+{
+  gimp_drawable_filter_sync_clip (filter, TRUE);
+  gimp_drawable_filter_update_drawable (filter, NULL);
+}
+
+static void
+gimp_drawable_filter_format_changed (GimpDrawable       *drawable,
+                                     GimpDrawableFilter *filter)
+{
+  gimp_drawable_filter_sync_format (filter);
+  gimp_drawable_filter_update_drawable (filter, NULL);
+}
+
+static void
+gimp_drawable_filter_drawable_removed (GimpDrawable       *drawable,
+                                       GimpDrawableFilter *filter)
+{
+  gimp_drawable_filter_remove_filter (filter);
+}
+
+static void
+gimp_drawable_filter_lock_alpha_changed (GimpLayer          *layer,
+                                         GimpDrawableFilter *filter)
+{
+  gimp_drawable_filter_sync_affect (filter);
+  gimp_drawable_filter_update_drawable (filter, NULL);
+}
diff --git a/app/core/gimpdrawablefilter.h b/app/core/gimpdrawablefilter.h
new file mode 100644
index 0000000..5aa8324
--- /dev/null
+++ b/app/core/gimpdrawablefilter.h
@@ -0,0 +1,108 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_DRAWABLE_FILTER_H__
+#define __GIMP_DRAWABLE_FILTER_H__
+
+
+#include "gimpfilter.h"
+
+
+#define GIMP_TYPE_DRAWABLE_FILTER            (gimp_drawable_filter_get_type ())
+#define GIMP_DRAWABLE_FILTER(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_DRAWABLE_FILTER, GimpDrawableFilter))
+#define GIMP_DRAWABLE_FILTER_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_DRAWABLE_FILTER, GimpDrawableFilterClass))
+#define GIMP_IS_DRAWABLE_FILTER(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_DRAWABLE_FILTER))
+#define GIMP_IS_DRAWABLE_FILTER_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_DRAWABLE_FILTER))
+#define GIMP_DRAWABLE_FILTER_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_DRAWABLE_FILTER, GimpDrawableFilterClass))
+
+
+typedef struct _GimpDrawableFilterClass  GimpDrawableFilterClass;
+
+struct _GimpDrawableFilterClass
+{
+  GimpFilterClass  parent_class;
+
+  void (* flush) (GimpDrawableFilter *filter);
+};
+
+
+/*  Drawable Filter functions  */
+
+/*  Successive apply() functions can be called, but eventually MUST be
+ *  followed with an commit() or an abort() call, both of which will
+ *  remove the live filter from the drawable.
+ */
+
+GType      gimp_drawable_filter_get_type       (void) G_GNUC_CONST;
+
+GimpDrawableFilter *
+           gimp_drawable_filter_new            (GimpDrawable        *drawable,
+                                                const gchar         *undo_desc,
+                                                GeglNode            *operation,
+                                                const gchar         *icon_name);
+
+GimpDrawable *
+           gimp_drawable_filter_get_drawable   (GimpDrawableFilter  *filter);
+GeglNode * gimp_drawable_filter_get_operation  (GimpDrawableFilter  *filter);
+
+void       gimp_drawable_filter_set_clip       (GimpDrawableFilter  *filter,
+                                                gboolean             clip);
+void       gimp_drawable_filter_set_region     (GimpDrawableFilter  *filter,
+                                                GimpFilterRegion     region);
+void       gimp_drawable_filter_set_crop       (GimpDrawableFilter  *filter,
+                                                const GeglRectangle *rect,
+                                                gboolean             update);
+void       gimp_drawable_filter_set_preview    (GimpDrawableFilter  *filter,
+                                                gboolean             enabled);
+void       gimp_drawable_filter_set_preview_split
+                                               (GimpDrawableFilter  *filter,
+                                                gboolean             enabled,
+                                                GimpAlignmentType    alignment,
+                                                gint                 split_position);
+void       gimp_drawable_filter_set_opacity    (GimpDrawableFilter  *filter,
+                                                gdouble              opacity);
+void       gimp_drawable_filter_set_mode       (GimpDrawableFilter  *filter,
+                                                GimpLayerMode        paint_mode,
+                                                GimpLayerColorSpace  blend_space,
+                                                GimpLayerColorSpace  composite_space,
+                                                GimpLayerCompositeMode composite_mode);
+void       gimp_drawable_filter_set_add_alpha  (GimpDrawableFilter  *filter,
+                                                gboolean             add_alpha);
+
+void       gimp_drawable_filter_set_color_managed
+                                               (GimpDrawableFilter  *filter,
+                                                gboolean             managed);
+void       gimp_drawable_filter_set_gamma_hack (GimpDrawableFilter  *filter,
+                                                gboolean             gamma_hack);
+
+void       gimp_drawable_filter_set_override_constraints
+                                               (GimpDrawableFilter  *filter,
+                                                gboolean             override_constraints);
+
+const Babl *
+           gimp_drawable_filter_get_format     (GimpDrawableFilter  *filter);
+
+void       gimp_drawable_filter_apply          (GimpDrawableFilter  *filter,
+                                                const GeglRectangle *area);
+
+gboolean   gimp_drawable_filter_commit         (GimpDrawableFilter  *filter,
+                                                GimpProgress        *progress,
+                                                gboolean             cancellable);
+void       gimp_drawable_filter_abort          (GimpDrawableFilter  *filter);
+
+
+#endif /* __GIMP_DRAWABLE_FILTER_H__ */
diff --git a/app/core/gimpdrawablemodundo.c b/app/core/gimpdrawablemodundo.c
new file mode 100644
index 0000000..5c3e897
--- /dev/null
+++ b/app/core/gimpdrawablemodundo.c
@@ -0,0 +1,216 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gegl/gimp-gegl-utils.h"
+
+#include "gimp-memsize.h"
+#include "gimpimage.h"
+#include "gimpdrawable.h"
+#include "gimpdrawablemodundo.h"
+
+
+enum
+{
+  PROP_0,
+  PROP_COPY_BUFFER
+};
+
+
+static void     gimp_drawable_mod_undo_constructed  (GObject             *object);
+static void     gimp_drawable_mod_undo_set_property (GObject             *object,
+                                                     guint                property_id,
+                                                     const GValue        *value,
+                                                     GParamSpec          *pspec);
+static void     gimp_drawable_mod_undo_get_property (GObject             *object,
+                                                     guint                property_id,
+                                                     GValue              *value,
+                                                     GParamSpec          *pspec);
+
+static gint64   gimp_drawable_mod_undo_get_memsize  (GimpObject          *object,
+                                                     gint64              *gui_size);
+
+static void     gimp_drawable_mod_undo_pop          (GimpUndo            *undo,
+                                                     GimpUndoMode         undo_mode,
+                                                     GimpUndoAccumulator *accum);
+static void     gimp_drawable_mod_undo_free         (GimpUndo            *undo,
+                                                     GimpUndoMode         undo_mode);
+
+
+G_DEFINE_TYPE (GimpDrawableModUndo, gimp_drawable_mod_undo, GIMP_TYPE_ITEM_UNDO)
+
+#define parent_class gimp_drawable_mod_undo_parent_class
+
+
+static void
+gimp_drawable_mod_undo_class_init (GimpDrawableModUndoClass *klass)
+{
+  GObjectClass    *object_class      = G_OBJECT_CLASS (klass);
+  GimpObjectClass *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+  GimpUndoClass   *undo_class        = GIMP_UNDO_CLASS (klass);
+
+  object_class->constructed      = gimp_drawable_mod_undo_constructed;
+  object_class->set_property     = gimp_drawable_mod_undo_set_property;
+  object_class->get_property     = gimp_drawable_mod_undo_get_property;
+
+  gimp_object_class->get_memsize = gimp_drawable_mod_undo_get_memsize;
+
+  undo_class->pop                = gimp_drawable_mod_undo_pop;
+  undo_class->free               = gimp_drawable_mod_undo_free;
+
+  g_object_class_install_property (object_class, PROP_COPY_BUFFER,
+                                   g_param_spec_boolean ("copy-buffer",
+                                                         NULL, NULL,
+                                                         FALSE,
+                                                         GIMP_PARAM_READWRITE |
+                                                         G_PARAM_CONSTRUCT_ONLY));
+}
+
+static void
+gimp_drawable_mod_undo_init (GimpDrawableModUndo *undo)
+{
+}
+
+static void
+gimp_drawable_mod_undo_constructed (GObject *object)
+{
+  GimpDrawableModUndo *drawable_mod_undo = GIMP_DRAWABLE_MOD_UNDO (object);
+  GimpItem            *item;
+  GimpDrawable        *drawable;
+
+  G_OBJECT_CLASS (parent_class)->constructed (object);
+
+  gimp_assert (GIMP_IS_DRAWABLE (GIMP_ITEM_UNDO (object)->item));
+
+  item     = GIMP_ITEM_UNDO (object)->item;
+  drawable = GIMP_DRAWABLE (item);
+
+  if (drawable_mod_undo->copy_buffer)
+    {
+      drawable_mod_undo->buffer =
+        gimp_gegl_buffer_dup (gimp_drawable_get_buffer (drawable));
+    }
+  else
+    {
+      drawable_mod_undo->buffer =
+        g_object_ref (gimp_drawable_get_buffer (drawable));
+    }
+
+  gimp_item_get_offset (item,
+                        &drawable_mod_undo->offset_x,
+                        &drawable_mod_undo->offset_y);
+}
+
+static void
+gimp_drawable_mod_undo_set_property (GObject      *object,
+                                     guint         property_id,
+                                     const GValue *value,
+                                     GParamSpec   *pspec)
+{
+  GimpDrawableModUndo *drawable_mod_undo = GIMP_DRAWABLE_MOD_UNDO (object);
+
+  switch (property_id)
+    {
+    case PROP_COPY_BUFFER:
+      drawable_mod_undo->copy_buffer = g_value_get_boolean (value);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_drawable_mod_undo_get_property (GObject    *object,
+                                     guint       property_id,
+                                     GValue     *value,
+                                     GParamSpec *pspec)
+{
+  GimpDrawableModUndo *drawable_mod_undo = GIMP_DRAWABLE_MOD_UNDO (object);
+
+  switch (property_id)
+    {
+    case PROP_COPY_BUFFER:
+      g_value_set_boolean (value, drawable_mod_undo->copy_buffer);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static gint64
+gimp_drawable_mod_undo_get_memsize (GimpObject *object,
+                                    gint64     *gui_size)
+{
+  GimpDrawableModUndo *drawable_mod_undo = GIMP_DRAWABLE_MOD_UNDO (object);
+  gint64               memsize           = 0;
+
+  memsize += gimp_gegl_buffer_get_memsize (drawable_mod_undo->buffer);
+
+  return memsize + GIMP_OBJECT_CLASS (parent_class)->get_memsize (object,
+                                                                  gui_size);
+}
+
+static void
+gimp_drawable_mod_undo_pop (GimpUndo            *undo,
+                            GimpUndoMode         undo_mode,
+                            GimpUndoAccumulator *accum)
+{
+  GimpDrawableModUndo *drawable_mod_undo = GIMP_DRAWABLE_MOD_UNDO (undo);
+  GimpDrawable        *drawable          = GIMP_DRAWABLE (GIMP_ITEM_UNDO (undo)->item);
+  GeglBuffer          *buffer;
+  gint                 offset_x;
+  gint                 offset_y;
+
+  GIMP_UNDO_CLASS (parent_class)->pop (undo, undo_mode, accum);
+
+  buffer   = drawable_mod_undo->buffer;
+  offset_x = drawable_mod_undo->offset_x;
+  offset_y = drawable_mod_undo->offset_y;
+
+  drawable_mod_undo->buffer = g_object_ref (gimp_drawable_get_buffer (drawable));
+
+  gimp_item_get_offset (GIMP_ITEM (drawable),
+                        &drawable_mod_undo->offset_x,
+                        &drawable_mod_undo->offset_y);
+
+  gimp_drawable_set_buffer_full (drawable, FALSE, NULL,
+                                 buffer,
+                                 GEGL_RECTANGLE (offset_x, offset_y, 0, 0),
+                                 TRUE);
+  g_object_unref (buffer);
+}
+
+static void
+gimp_drawable_mod_undo_free (GimpUndo     *undo,
+                             GimpUndoMode  undo_mode)
+{
+  GimpDrawableModUndo *drawable_mod_undo = GIMP_DRAWABLE_MOD_UNDO (undo);
+
+  g_clear_object (&drawable_mod_undo->buffer);
+
+  GIMP_UNDO_CLASS (parent_class)->free (undo, undo_mode);
+}
diff --git a/app/core/gimpdrawablemodundo.h b/app/core/gimpdrawablemodundo.h
new file mode 100644
index 0000000..30bf5a0
--- /dev/null
+++ b/app/core/gimpdrawablemodundo.h
@@ -0,0 +1,55 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_DRAWABLE_MOD_UNDO_H__
+#define __GIMP_DRAWABLE_MOD_UNDO_H__
+
+
+#include "gimpitemundo.h"
+
+
+#define GIMP_TYPE_DRAWABLE_MOD_UNDO            (gimp_drawable_mod_undo_get_type ())
+#define GIMP_DRAWABLE_MOD_UNDO(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_DRAWABLE_MOD_UNDO, GimpDrawableModUndo))
+#define GIMP_DRAWABLE_MOD_UNDO_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_DRAWABLE_MOD_UNDO, GimpDrawableModUndoClass))
+#define GIMP_IS_DRAWABLE_MOD_UNDO(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_DRAWABLE_MOD_UNDO))
+#define GIMP_IS_DRAWABLE_MOD_UNDO_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_DRAWABLE_MOD_UNDO))
+#define GIMP_DRAWABLE_MOD_UNDO_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_DRAWABLE_MOD_UNDO, GimpDrawableModUndoClass))
+
+
+typedef struct _GimpDrawableModUndo      GimpDrawableModUndo;
+typedef struct _GimpDrawableModUndoClass GimpDrawableModUndoClass;
+
+struct _GimpDrawableModUndo
+{
+  GimpItemUndo   parent_instance;
+
+  GeglBuffer    *buffer;
+  gboolean       copy_buffer;
+  gint           offset_x;
+  gint           offset_y;
+};
+
+struct _GimpDrawableModUndoClass
+{
+  GimpItemUndoClass  parent_class;
+};
+
+
+GType   gimp_drawable_mod_undo_get_type (void) G_GNUC_CONST;
+
+
+#endif /* __GIMP_DRAWABLE_MOD_UNDO_H__ */
diff --git a/app/core/gimpdrawablestack.c b/app/core/gimpdrawablestack.c
new file mode 100644
index 0000000..c8e706a
--- /dev/null
+++ b/app/core/gimpdrawablestack.c
@@ -0,0 +1,224 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1997 Spencer Kimball and Peter Mattis
+ *
+ * gimpdrawablestack.c
+ * Copyright (C) 2008 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gimpdrawable.h"
+#include "gimpdrawablestack.h"
+#include "gimpmarshal.h"
+
+
+enum
+{
+  UPDATE,
+  LAST_SIGNAL
+};
+
+
+/*  local function prototypes  */
+
+static void   gimp_drawable_stack_constructed      (GObject           *object);
+
+static void   gimp_drawable_stack_add              (GimpContainer     *container,
+                                                    GimpObject        *object);
+static void   gimp_drawable_stack_remove           (GimpContainer     *container,
+                                                    GimpObject        *object);
+static void   gimp_drawable_stack_reorder          (GimpContainer     *container,
+                                                    GimpObject        *object,
+                                                    gint               new_index);
+
+static void   gimp_drawable_stack_drawable_update  (GimpItem          *item,
+                                                    gint               x,
+                                                    gint               y,
+                                                    gint               width,
+                                                    gint               height,
+                                                    GimpDrawableStack *stack);
+static void   gimp_drawable_stack_drawable_active  (GimpItem          *item,
+                                                    GimpDrawableStack *stack);
+
+
+G_DEFINE_TYPE (GimpDrawableStack, gimp_drawable_stack, GIMP_TYPE_ITEM_STACK)
+
+#define parent_class gimp_drawable_stack_parent_class
+
+static guint stack_signals[LAST_SIGNAL] = { 0 };
+
+
+static void
+gimp_drawable_stack_class_init (GimpDrawableStackClass *klass)
+{
+  GObjectClass       *object_class    = G_OBJECT_CLASS (klass);
+  GimpContainerClass *container_class = GIMP_CONTAINER_CLASS (klass);
+
+  stack_signals[UPDATE] =
+    g_signal_new ("update",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpDrawableStackClass, update),
+                  NULL, NULL,
+                  gimp_marshal_VOID__INT_INT_INT_INT,
+                  G_TYPE_NONE, 4,
+                  G_TYPE_INT,
+                  G_TYPE_INT,
+                  G_TYPE_INT,
+                  G_TYPE_INT);
+
+  object_class->constructed = gimp_drawable_stack_constructed;
+
+  container_class->add      = gimp_drawable_stack_add;
+  container_class->remove   = gimp_drawable_stack_remove;
+  container_class->reorder  = gimp_drawable_stack_reorder;
+}
+
+static void
+gimp_drawable_stack_init (GimpDrawableStack *stack)
+{
+}
+
+static void
+gimp_drawable_stack_constructed (GObject *object)
+{
+  GimpContainer *container = GIMP_CONTAINER (object);
+
+  G_OBJECT_CLASS (parent_class)->constructed (object);
+
+  gimp_assert (g_type_is_a (gimp_container_get_children_type (container),
+                            GIMP_TYPE_DRAWABLE));
+
+  gimp_container_add_handler (container, "update",
+                              G_CALLBACK (gimp_drawable_stack_drawable_update),
+                              container);
+  gimp_container_add_handler (container, "active-changed",
+                              G_CALLBACK (gimp_drawable_stack_drawable_active),
+                              container);
+}
+
+static void
+gimp_drawable_stack_add (GimpContainer *container,
+                         GimpObject    *object)
+{
+  GimpDrawableStack *stack = GIMP_DRAWABLE_STACK (container);
+
+  GIMP_CONTAINER_CLASS (parent_class)->add (container, object);
+
+  if (gimp_filter_get_active (GIMP_FILTER (object)))
+    gimp_drawable_stack_drawable_active (GIMP_ITEM (object), stack);
+}
+
+static void
+gimp_drawable_stack_remove (GimpContainer *container,
+                            GimpObject    *object)
+{
+  GimpDrawableStack *stack = GIMP_DRAWABLE_STACK (container);
+
+  GIMP_CONTAINER_CLASS (parent_class)->remove (container, object);
+
+  if (gimp_filter_get_active (GIMP_FILTER (object)))
+    gimp_drawable_stack_drawable_active (GIMP_ITEM (object), stack);
+}
+
+static void
+gimp_drawable_stack_reorder (GimpContainer *container,
+                             GimpObject    *object,
+                             gint           new_index)
+{
+  GimpDrawableStack *stack  = GIMP_DRAWABLE_STACK (container);
+
+  GIMP_CONTAINER_CLASS (parent_class)->reorder (container, object, new_index);
+
+  if (gimp_filter_get_active (GIMP_FILTER (object)))
+    gimp_drawable_stack_drawable_active (GIMP_ITEM (object), stack);
+}
+
+
+/*  public functions  */
+
+GimpContainer *
+gimp_drawable_stack_new (GType drawable_type)
+{
+  g_return_val_if_fail (g_type_is_a (drawable_type, GIMP_TYPE_DRAWABLE), NULL);
+
+  return g_object_new (GIMP_TYPE_DRAWABLE_STACK,
+                       "name",          g_type_name (drawable_type),
+                       "children-type", drawable_type,
+                       "policy",        GIMP_CONTAINER_POLICY_STRONG,
+                       NULL);
+}
+
+
+/*  protected functions  */
+
+void
+gimp_drawable_stack_update (GimpDrawableStack *stack,
+                            gint               x,
+                            gint               y,
+                            gint               width,
+                            gint               height)
+{
+  g_return_if_fail (GIMP_IS_DRAWABLE_STACK (stack));
+
+  g_signal_emit (stack, stack_signals[UPDATE], 0,
+                 x, y, width, height);
+}
+
+
+/*  private functions  */
+
+static void
+gimp_drawable_stack_drawable_update (GimpItem          *item,
+                                     gint               x,
+                                     gint               y,
+                                     gint               width,
+                                     gint               height,
+                                     GimpDrawableStack *stack)
+{
+  if (gimp_filter_get_active (GIMP_FILTER (item)))
+    {
+      gint offset_x;
+      gint offset_y;
+
+      gimp_item_get_offset (item, &offset_x, &offset_y);
+
+      gimp_drawable_stack_update (stack,
+                                  x + offset_x, y + offset_y,
+                                  width, height);
+    }
+}
+
+static void
+gimp_drawable_stack_drawable_active (GimpItem          *item,
+                                     GimpDrawableStack *stack)
+{
+  GeglRectangle bounding_box;
+
+  bounding_box = gimp_drawable_get_bounding_box (GIMP_DRAWABLE (item));
+
+  bounding_box.x += gimp_item_get_offset_x (item);
+  bounding_box.y += gimp_item_get_offset_y (item);
+
+  gimp_drawable_stack_update (stack,
+                              bounding_box.x,     bounding_box.y,
+                              bounding_box.width, bounding_box.height);
+}
diff --git a/app/core/gimpdrawablestack.h b/app/core/gimpdrawablestack.h
new file mode 100644
index 0000000..28ee7c4
--- /dev/null
+++ b/app/core/gimpdrawablestack.h
@@ -0,0 +1,66 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1997 Spencer Kimball and Peter Mattis
+ *
+ * gimpdrawablestack.h
+ * Copyright (C) 2008 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_DRAWABLE_STACK_H__
+#define __GIMP_DRAWABLE_STACK_H__
+
+#include "gimpitemstack.h"
+
+
+#define GIMP_TYPE_DRAWABLE_STACK            (gimp_drawable_stack_get_type ())
+#define GIMP_DRAWABLE_STACK(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_DRAWABLE_STACK, GimpDrawableStack))
+#define GIMP_DRAWABLE_STACK_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_DRAWABLE_STACK, GimpDrawableStackClass))
+#define GIMP_IS_DRAWABLE_STACK(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_DRAWABLE_STACK))
+#define GIMP_IS_DRAWABLE_STACK_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_DRAWABLE_STACK))
+
+
+typedef struct _GimpDrawableStackClass GimpDrawableStackClass;
+
+struct _GimpDrawableStack
+{
+  GimpItemStack  parent_instance;
+};
+
+struct _GimpDrawableStackClass
+{
+  GimpItemStackClass  parent_class;
+
+  void (* update) (GimpDrawableStack *stack,
+                   gint               x,
+                   gint               y,
+                   gint               width,
+                   gint               height);
+};
+
+
+GType           gimp_drawable_stack_get_type  (void) G_GNUC_CONST;
+GimpContainer * gimp_drawable_stack_new       (GType              drawable_type);
+
+
+/*  protected  */
+
+void            gimp_drawable_stack_update    (GimpDrawableStack *stack,
+                                               gint               x,
+                                               gint               y,
+                                               gint               width,
+                                               gint               height);
+
+
+#endif  /*  __GIMP_DRAWABLE_STACK_H__  */
diff --git a/app/core/gimpdrawableundo.c b/app/core/gimpdrawableundo.c
new file mode 100644
index 0000000..78b8f39
--- /dev/null
+++ b/app/core/gimpdrawableundo.c
@@ -0,0 +1,207 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+
+#include "core-types.h"
+
+#include "gimp-memsize.h"
+#include "gimpimage.h"
+#include "gimpdrawable.h"
+#include "gimpdrawableundo.h"
+
+
+enum
+{
+  PROP_0,
+  PROP_BUFFER,
+  PROP_X,
+  PROP_Y
+};
+
+
+static void     gimp_drawable_undo_constructed  (GObject             *object);
+static void     gimp_drawable_undo_set_property (GObject             *object,
+                                                 guint                property_id,
+                                                 const GValue        *value,
+                                                 GParamSpec          *pspec);
+static void     gimp_drawable_undo_get_property (GObject             *object,
+                                                 guint                property_id,
+                                                 GValue              *value,
+                                                 GParamSpec          *pspec);
+
+static gint64   gimp_drawable_undo_get_memsize  (GimpObject          *object,
+                                                 gint64              *gui_size);
+
+static void     gimp_drawable_undo_pop          (GimpUndo            *undo,
+                                                 GimpUndoMode         undo_mode,
+                                                 GimpUndoAccumulator *accum);
+static void     gimp_drawable_undo_free         (GimpUndo            *undo,
+                                                 GimpUndoMode         undo_mode);
+
+
+G_DEFINE_TYPE (GimpDrawableUndo, gimp_drawable_undo, GIMP_TYPE_ITEM_UNDO)
+
+#define parent_class gimp_drawable_undo_parent_class
+
+
+static void
+gimp_drawable_undo_class_init (GimpDrawableUndoClass *klass)
+{
+  GObjectClass    *object_class      = G_OBJECT_CLASS (klass);
+  GimpObjectClass *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+  GimpUndoClass   *undo_class        = GIMP_UNDO_CLASS (klass);
+
+  object_class->constructed      = gimp_drawable_undo_constructed;
+  object_class->set_property     = gimp_drawable_undo_set_property;
+  object_class->get_property     = gimp_drawable_undo_get_property;
+
+  gimp_object_class->get_memsize = gimp_drawable_undo_get_memsize;
+
+  undo_class->pop                = gimp_drawable_undo_pop;
+  undo_class->free               = gimp_drawable_undo_free;
+
+  g_object_class_install_property (object_class, PROP_BUFFER,
+                                   g_param_spec_object ("buffer", NULL, NULL,
+                                                        GEGL_TYPE_BUFFER,
+                                                        GIMP_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT_ONLY));
+
+  g_object_class_install_property (object_class, PROP_X,
+                                   g_param_spec_int ("x", NULL, NULL,
+                                                     0, GIMP_MAX_IMAGE_SIZE, 0,
+                                                     GIMP_PARAM_READWRITE |
+                                                     G_PARAM_CONSTRUCT_ONLY));
+
+  g_object_class_install_property (object_class, PROP_Y,
+                                   g_param_spec_int ("y", NULL, NULL,
+                                                     0, GIMP_MAX_IMAGE_SIZE, 0,
+                                                     GIMP_PARAM_READWRITE |
+                                                     G_PARAM_CONSTRUCT_ONLY));
+}
+
+static void
+gimp_drawable_undo_init (GimpDrawableUndo *undo)
+{
+}
+
+static void
+gimp_drawable_undo_constructed (GObject *object)
+{
+  GimpDrawableUndo *drawable_undo = GIMP_DRAWABLE_UNDO (object);
+
+  G_OBJECT_CLASS (parent_class)->constructed (object);
+
+  gimp_assert (GIMP_IS_DRAWABLE (GIMP_ITEM_UNDO (object)->item));
+  gimp_assert (GEGL_IS_BUFFER (drawable_undo->buffer));
+}
+
+static void
+gimp_drawable_undo_set_property (GObject      *object,
+                                 guint         property_id,
+                                 const GValue *value,
+                                 GParamSpec   *pspec)
+{
+  GimpDrawableUndo *drawable_undo = GIMP_DRAWABLE_UNDO (object);
+
+  switch (property_id)
+    {
+    case PROP_BUFFER:
+      drawable_undo->buffer = g_value_dup_object (value);
+      break;
+    case PROP_X:
+      drawable_undo->x = g_value_get_int (value);
+      break;
+    case PROP_Y:
+      drawable_undo->y = g_value_get_int (value);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_drawable_undo_get_property (GObject    *object,
+                                 guint       property_id,
+                                 GValue     *value,
+                                 GParamSpec *pspec)
+{
+  GimpDrawableUndo *drawable_undo = GIMP_DRAWABLE_UNDO (object);
+
+  switch (property_id)
+    {
+    case PROP_BUFFER:
+      g_value_set_object (value, drawable_undo->buffer);
+      break;
+    case PROP_X:
+      g_value_set_int (value, drawable_undo->x);
+      break;
+    case PROP_Y:
+      g_value_set_int (value, drawable_undo->y);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static gint64
+gimp_drawable_undo_get_memsize (GimpObject *object,
+                                gint64     *gui_size)
+{
+  GimpDrawableUndo *drawable_undo = GIMP_DRAWABLE_UNDO (object);
+  gint64            memsize       = 0;
+
+  memsize += gimp_gegl_buffer_get_memsize (drawable_undo->buffer);
+
+  return memsize + GIMP_OBJECT_CLASS (parent_class)->get_memsize (object,
+                                                                  gui_size);
+}
+
+static void
+gimp_drawable_undo_pop (GimpUndo            *undo,
+                        GimpUndoMode         undo_mode,
+                        GimpUndoAccumulator *accum)
+{
+  GimpDrawableUndo *drawable_undo = GIMP_DRAWABLE_UNDO (undo);
+
+  GIMP_UNDO_CLASS (parent_class)->pop (undo, undo_mode, accum);
+
+  gimp_drawable_swap_pixels (GIMP_DRAWABLE (GIMP_ITEM_UNDO (undo)->item),
+                             drawable_undo->buffer,
+                             drawable_undo->x,
+                             drawable_undo->y);
+}
+
+static void
+gimp_drawable_undo_free (GimpUndo     *undo,
+                         GimpUndoMode  undo_mode)
+{
+  GimpDrawableUndo *drawable_undo = GIMP_DRAWABLE_UNDO (undo);
+
+  g_clear_object (&drawable_undo->buffer);
+
+  GIMP_UNDO_CLASS (parent_class)->free (undo, undo_mode);
+}
diff --git a/app/core/gimpdrawableundo.h b/app/core/gimpdrawableundo.h
new file mode 100644
index 0000000..5d7269e
--- /dev/null
+++ b/app/core/gimpdrawableundo.h
@@ -0,0 +1,54 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_DRAWABLE_UNDO_H__
+#define __GIMP_DRAWABLE_UNDO_H__
+
+
+#include "gimpitemundo.h"
+
+
+#define GIMP_TYPE_DRAWABLE_UNDO            (gimp_drawable_undo_get_type ())
+#define GIMP_DRAWABLE_UNDO(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_DRAWABLE_UNDO, GimpDrawableUndo))
+#define GIMP_DRAWABLE_UNDO_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_DRAWABLE_UNDO, GimpDrawableUndoClass))
+#define GIMP_IS_DRAWABLE_UNDO(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_DRAWABLE_UNDO))
+#define GIMP_IS_DRAWABLE_UNDO_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_DRAWABLE_UNDO))
+#define GIMP_DRAWABLE_UNDO_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_DRAWABLE_UNDO, GimpDrawableUndoClass))
+
+
+typedef struct _GimpDrawableUndo      GimpDrawableUndo;
+typedef struct _GimpDrawableUndoClass GimpDrawableUndoClass;
+
+struct _GimpDrawableUndo
+{
+  GimpItemUndo  parent_instance;
+
+  GeglBuffer   *buffer;
+  gint          x;
+  gint          y;
+};
+
+struct _GimpDrawableUndoClass
+{
+  GimpItemUndoClass  parent_class;
+};
+
+
+GType   gimp_drawable_undo_get_type (void) G_GNUC_CONST;
+
+
+#endif /* __GIMP_DRAWABLE_UNDO_H__ */
diff --git a/app/core/gimpdynamics-load.c b/app/core/gimpdynamics-load.c
new file mode 100644
index 0000000..36c9f72
--- /dev/null
+++ b/app/core/gimpdynamics-load.c
@@ -0,0 +1,55 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpconfig/gimpconfig.h"
+
+#include "core-types.h"
+
+#include "gimpdynamics.h"
+#include "gimpdynamics-load.h"
+
+
+GList *
+gimp_dynamics_load (GimpContext   *context,
+                    GFile         *file,
+                    GInputStream  *input,
+                    GError       **error)
+{
+  GimpDynamics *dynamics;
+
+  g_return_val_if_fail (G_IS_FILE (file), NULL);
+  g_return_val_if_fail (G_IS_INPUT_STREAM (input), NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, NULL);
+
+  dynamics = g_object_new (GIMP_TYPE_DYNAMICS, NULL);
+
+  if (gimp_config_deserialize_stream (GIMP_CONFIG (dynamics),
+                                      input,
+                                      NULL, error))
+    {
+      return g_list_prepend (NULL, dynamics);
+    }
+
+  g_object_unref (dynamics);
+
+  return NULL;
+}
diff --git a/app/core/gimpdynamics-load.h b/app/core/gimpdynamics-load.h
new file mode 100644
index 0000000..374c6ed
--- /dev/null
+++ b/app/core/gimpdynamics-load.h
@@ -0,0 +1,31 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_DYNAMICS_LOAD_H__
+#define __GIMP_DYNAMICS_LOAD_H__
+
+
+#define GIMP_DYNAMICS_FILE_EXTENSION ".gdyn"
+
+
+GList * gimp_dynamics_load (GimpContext   *context,
+                            GFile         *file,
+                            GInputStream  *input,
+                            GError       **error);
+
+
+#endif /* __GIMP_DYNAMICS_LOAD_H__ */
diff --git a/app/core/gimpdynamics-save.c b/app/core/gimpdynamics-save.c
new file mode 100644
index 0000000..d8bdf3d
--- /dev/null
+++ b/app/core/gimpdynamics-save.c
@@ -0,0 +1,44 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpconfig/gimpconfig.h"
+
+#include "core-types.h"
+
+#include "gimpdynamics.h"
+#include "gimpdynamics-save.h"
+
+
+gboolean
+gimp_dynamics_save (GimpData       *data,
+                    GOutputStream  *output,
+                    GError        **error)
+{
+  g_return_val_if_fail (GIMP_IS_DYNAMICS (data), FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  return gimp_config_serialize_to_stream (GIMP_CONFIG (data),
+                                          output,
+                                          "GIMP dynamics file",
+                                          "end of GIMP dynamics file",
+                                          NULL, error);
+}
diff --git a/app/core/gimpdynamics-save.h b/app/core/gimpdynamics-save.h
new file mode 100644
index 0000000..7fe2df3
--- /dev/null
+++ b/app/core/gimpdynamics-save.h
@@ -0,0 +1,28 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_DYNAMICS_SAVE_H__
+#define __GIMP_DYNAMICS_SAVE_H__
+
+
+/*  don't call this function directly, use gimp_data_save() instead  */
+gboolean   gimp_dynamics_save (GimpData       *data,
+                               GOutputStream  *output,
+                               GError        **error);
+
+
+#endif /* __GIMP_DYNAMICS_SAVE_H__ */
diff --git a/app/core/gimpdynamics.c b/app/core/gimpdynamics.c
new file mode 100644
index 0000000..a1fb0ef
--- /dev/null
+++ b/app/core/gimpdynamics.c
@@ -0,0 +1,653 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1999 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpmath/gimpmath.h"
+#include "libgimpconfig/gimpconfig.h"
+
+#include "core-types.h"
+
+#include "gimpcurve.h"
+#include "gimpdynamics.h"
+#include "gimpdynamics-load.h"
+#include "gimpdynamics-save.h"
+#include "gimpdynamicsoutput.h"
+
+#include "gimp-intl.h"
+
+
+#define DEFAULT_NAME "Nameless dynamics"
+
+enum
+{
+  PROP_0,
+
+  PROP_NAME,
+
+  PROP_OPACITY_OUTPUT,
+  PROP_SIZE_OUTPUT,
+  PROP_ANGLE_OUTPUT,
+  PROP_COLOR_OUTPUT,
+  PROP_FORCE_OUTPUT,
+  PROP_HARDNESS_OUTPUT,
+  PROP_ASPECT_RATIO_OUTPUT,
+  PROP_SPACING_OUTPUT,
+  PROP_RATE_OUTPUT,
+  PROP_FLOW_OUTPUT,
+  PROP_JITTER_OUTPUT
+};
+
+
+typedef struct _GimpDynamicsPrivate GimpDynamicsPrivate;
+
+struct _GimpDynamicsPrivate
+{
+  GimpDynamicsOutput *opacity_output;
+  GimpDynamicsOutput *hardness_output;
+  GimpDynamicsOutput *force_output;
+  GimpDynamicsOutput *rate_output;
+  GimpDynamicsOutput *flow_output;
+  GimpDynamicsOutput *size_output;
+  GimpDynamicsOutput *aspect_ratio_output;
+  GimpDynamicsOutput *color_output;
+  GimpDynamicsOutput *angle_output;
+  GimpDynamicsOutput *jitter_output;
+  GimpDynamicsOutput *spacing_output;
+};
+
+#define GET_PRIVATE(output) \
+        ((GimpDynamicsPrivate *) gimp_dynamics_get_instance_private ((GimpDynamics *) (output)))
+
+
+static void          gimp_dynamics_finalize      (GObject      *object);
+static void          gimp_dynamics_set_property  (GObject      *object,
+                                                  guint         property_id,
+                                                  const GValue *value,
+                                                  GParamSpec   *pspec);
+static void          gimp_dynamics_get_property  (GObject      *object,
+                                                  guint         property_id,
+                                                  GValue       *value,
+                                                  GParamSpec   *pspec);
+static void
+       gimp_dynamics_dispatch_properties_changed (GObject      *object,
+                                                  guint         n_pspecs,
+                                                  GParamSpec  **pspecs);
+
+static const gchar * gimp_dynamics_get_extension (GimpData     *data);
+static void          gimp_dynamics_copy          (GimpData     *data,
+                                                  GimpData     *src_data);
+
+static GimpDynamicsOutput *
+                     gimp_dynamics_create_output (GimpDynamics           *dynamics,
+                                                  const gchar            *name,
+                                                  GimpDynamicsOutputType  type);
+static void          gimp_dynamics_output_notify (GObject          *output,
+                                                  const GParamSpec *pspec,
+                                                  GimpDynamics     *dynamics);
+
+
+G_DEFINE_TYPE_WITH_PRIVATE (GimpDynamics, gimp_dynamics, GIMP_TYPE_DATA)
+
+#define parent_class gimp_dynamics_parent_class
+
+
+static void
+gimp_dynamics_class_init (GimpDynamicsClass *klass)
+{
+  GObjectClass      *object_class   = G_OBJECT_CLASS (klass);
+  GimpDataClass     *data_class     = GIMP_DATA_CLASS (klass);
+  GimpViewableClass *viewable_class = GIMP_VIEWABLE_CLASS (klass);
+
+  object_class->finalize                    = gimp_dynamics_finalize;
+  object_class->set_property                = gimp_dynamics_set_property;
+  object_class->get_property                = gimp_dynamics_get_property;
+  object_class->dispatch_properties_changed = gimp_dynamics_dispatch_properties_changed;
+
+  viewable_class->default_icon_name         = "gimp-dynamics";
+
+  data_class->save                          = gimp_dynamics_save;
+  data_class->get_extension                 = gimp_dynamics_get_extension;
+  data_class->copy                          = gimp_dynamics_copy;
+
+  GIMP_CONFIG_PROP_STRING (object_class, PROP_NAME,
+                           "name",
+                           NULL, NULL,
+                           DEFAULT_NAME,
+                           GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_OBJECT (object_class, PROP_OPACITY_OUTPUT,
+                           "opacity-output",
+                           NULL, NULL,
+                           GIMP_TYPE_DYNAMICS_OUTPUT,
+                           GIMP_CONFIG_PARAM_AGGREGATE);
+
+  GIMP_CONFIG_PROP_OBJECT (object_class, PROP_FORCE_OUTPUT,
+                           "force-output",
+                           NULL, NULL,
+                           GIMP_TYPE_DYNAMICS_OUTPUT,
+                           GIMP_CONFIG_PARAM_AGGREGATE);
+
+  GIMP_CONFIG_PROP_OBJECT (object_class, PROP_HARDNESS_OUTPUT,
+                           "hardness-output",
+                           NULL, NULL,
+                           GIMP_TYPE_DYNAMICS_OUTPUT,
+                           GIMP_CONFIG_PARAM_AGGREGATE);
+
+  GIMP_CONFIG_PROP_OBJECT (object_class, PROP_RATE_OUTPUT,
+                           "rate-output",
+                           NULL, NULL,
+                           GIMP_TYPE_DYNAMICS_OUTPUT,
+                           GIMP_CONFIG_PARAM_AGGREGATE);
+
+  GIMP_CONFIG_PROP_OBJECT (object_class, PROP_FLOW_OUTPUT,
+                           "flow-output",
+                           NULL, NULL,
+                           GIMP_TYPE_DYNAMICS_OUTPUT,
+                           GIMP_CONFIG_PARAM_AGGREGATE);
+
+  GIMP_CONFIG_PROP_OBJECT (object_class, PROP_SIZE_OUTPUT,
+                           "size-output",
+                           NULL, NULL,
+                           GIMP_TYPE_DYNAMICS_OUTPUT,
+                           GIMP_CONFIG_PARAM_AGGREGATE);
+
+  GIMP_CONFIG_PROP_OBJECT (object_class, PROP_ASPECT_RATIO_OUTPUT,
+                           "aspect-ratio-output",
+                           NULL, NULL,
+                           GIMP_TYPE_DYNAMICS_OUTPUT,
+                           GIMP_CONFIG_PARAM_AGGREGATE);
+
+  GIMP_CONFIG_PROP_OBJECT (object_class, PROP_COLOR_OUTPUT,
+                           "color-output",
+                           NULL, NULL,
+                           GIMP_TYPE_DYNAMICS_OUTPUT,
+                           GIMP_CONFIG_PARAM_AGGREGATE);
+
+  GIMP_CONFIG_PROP_OBJECT (object_class, PROP_ANGLE_OUTPUT,
+                           "angle-output",
+                           NULL, NULL,
+                           GIMP_TYPE_DYNAMICS_OUTPUT,
+                           GIMP_CONFIG_PARAM_AGGREGATE);
+
+  GIMP_CONFIG_PROP_OBJECT (object_class, PROP_JITTER_OUTPUT,
+                           "jitter-output",
+                           NULL, NULL,
+                           GIMP_TYPE_DYNAMICS_OUTPUT,
+                           GIMP_CONFIG_PARAM_AGGREGATE);
+
+  GIMP_CONFIG_PROP_OBJECT (object_class, PROP_SPACING_OUTPUT,
+                           "spacing-output",
+                           NULL, NULL,
+                           GIMP_TYPE_DYNAMICS_OUTPUT,
+                           GIMP_CONFIG_PARAM_AGGREGATE);
+}
+
+static void
+gimp_dynamics_init (GimpDynamics *dynamics)
+{
+  GimpDynamicsPrivate *private = GET_PRIVATE (dynamics);
+
+  private->opacity_output =
+    gimp_dynamics_create_output (dynamics,
+                                 "opacity-output",
+                                 GIMP_DYNAMICS_OUTPUT_OPACITY);
+
+  private->force_output =
+    gimp_dynamics_create_output (dynamics,
+                                 "force-output",
+                                 GIMP_DYNAMICS_OUTPUT_FORCE);
+
+  private->hardness_output =
+    gimp_dynamics_create_output (dynamics,
+                                 "hardness-output",
+                                 GIMP_DYNAMICS_OUTPUT_HARDNESS);
+
+  private->rate_output =
+    gimp_dynamics_create_output (dynamics,
+                                 "rate-output",
+                                 GIMP_DYNAMICS_OUTPUT_RATE);
+
+  private->flow_output =
+    gimp_dynamics_create_output (dynamics,
+                                 "flow-output",
+                                 GIMP_DYNAMICS_OUTPUT_FLOW);
+
+  private->size_output =
+    gimp_dynamics_create_output (dynamics,
+                                 "size-output",
+                                 GIMP_DYNAMICS_OUTPUT_SIZE);
+
+  private->aspect_ratio_output =
+    gimp_dynamics_create_output (dynamics,
+                                 "aspect-ratio-output",
+                                 GIMP_DYNAMICS_OUTPUT_ASPECT_RATIO);
+
+  private->color_output =
+    gimp_dynamics_create_output (dynamics,
+                                 "color-output",
+                                 GIMP_DYNAMICS_OUTPUT_COLOR);
+
+  private->angle_output =
+    gimp_dynamics_create_output (dynamics,
+                                 "angle-output",
+                                 GIMP_DYNAMICS_OUTPUT_ANGLE);
+
+  private->jitter_output =
+    gimp_dynamics_create_output (dynamics,
+                                 "jitter-output",
+                                 GIMP_DYNAMICS_OUTPUT_JITTER);
+
+  private->spacing_output =
+    gimp_dynamics_create_output (dynamics,
+                                 "spacing-output",
+                                 GIMP_DYNAMICS_OUTPUT_SPACING);
+}
+
+static void
+gimp_dynamics_finalize (GObject *object)
+{
+  GimpDynamicsPrivate *private = GET_PRIVATE (object);
+
+  g_clear_object (&private->opacity_output);
+  g_clear_object (&private->force_output);
+  g_clear_object (&private->hardness_output);
+  g_clear_object (&private->rate_output);
+  g_clear_object (&private->flow_output);
+  g_clear_object (&private->size_output);
+  g_clear_object (&private->aspect_ratio_output);
+  g_clear_object (&private->color_output);
+  g_clear_object (&private->angle_output);
+  g_clear_object (&private->jitter_output);
+  g_clear_object (&private->spacing_output);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gimp_dynamics_set_property (GObject      *object,
+                            guint         property_id,
+                            const GValue *value,
+                            GParamSpec   *pspec)
+{
+  GimpDynamicsPrivate *private     = GET_PRIVATE (object);
+  GimpDynamicsOutput  *src_output  = NULL;
+  GimpDynamicsOutput  *dest_output = NULL;
+
+  switch (property_id)
+    {
+    case PROP_NAME:
+      gimp_object_set_name (GIMP_OBJECT (object), g_value_get_string (value));
+      break;
+
+    case PROP_OPACITY_OUTPUT:
+      src_output  = g_value_get_object (value);
+      dest_output = private->opacity_output;
+      break;
+
+    case PROP_FORCE_OUTPUT:
+      src_output  = g_value_get_object (value);
+      dest_output = private->force_output;
+      break;
+
+    case PROP_HARDNESS_OUTPUT:
+      src_output  = g_value_get_object (value);
+      dest_output = private->hardness_output;
+      break;
+
+    case PROP_RATE_OUTPUT:
+      src_output  = g_value_get_object (value);
+      dest_output = private->rate_output;
+      break;
+
+    case PROP_FLOW_OUTPUT:
+      src_output  = g_value_get_object (value);
+      dest_output = private->flow_output;
+      break;
+
+    case PROP_SIZE_OUTPUT:
+      src_output  = g_value_get_object (value);
+      dest_output = private->size_output;
+      break;
+
+    case PROP_ASPECT_RATIO_OUTPUT:
+      src_output  = g_value_get_object (value);
+      dest_output = private->aspect_ratio_output;
+      break;
+
+    case PROP_COLOR_OUTPUT:
+      src_output  = g_value_get_object (value);
+      dest_output = private->color_output;
+      break;
+
+    case PROP_ANGLE_OUTPUT:
+      src_output  = g_value_get_object (value);
+      dest_output = private->angle_output;
+      break;
+
+    case PROP_JITTER_OUTPUT:
+      src_output  = g_value_get_object (value);
+      dest_output = private->jitter_output;
+      break;
+
+    case PROP_SPACING_OUTPUT:
+      src_output  = g_value_get_object (value);
+      dest_output = private->spacing_output;
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+
+  if (src_output && dest_output)
+    {
+      gimp_config_copy (GIMP_CONFIG (src_output),
+                        GIMP_CONFIG (dest_output),
+                        GIMP_CONFIG_PARAM_SERIALIZE);
+    }
+}
+
+static void
+gimp_dynamics_get_property (GObject    *object,
+                            guint       property_id,
+                            GValue     *value,
+                            GParamSpec *pspec)
+{
+  GimpDynamicsPrivate *private = GET_PRIVATE (object);
+
+  switch (property_id)
+    {
+    case PROP_NAME:
+      g_value_set_string (value, gimp_object_get_name (object));
+      break;
+
+    case PROP_OPACITY_OUTPUT:
+      g_value_set_object (value, private->opacity_output);
+      break;
+
+    case PROP_FORCE_OUTPUT:
+      g_value_set_object (value, private->force_output);
+      break;
+
+    case PROP_HARDNESS_OUTPUT:
+      g_value_set_object (value, private->hardness_output);
+      break;
+
+    case PROP_RATE_OUTPUT:
+      g_value_set_object (value, private->rate_output);
+      break;
+
+    case PROP_FLOW_OUTPUT:
+      g_value_set_object (value, private->flow_output);
+      break;
+
+    case PROP_SIZE_OUTPUT:
+      g_value_set_object (value, private->size_output);
+      break;
+
+    case PROP_ASPECT_RATIO_OUTPUT:
+      g_value_set_object (value, private->aspect_ratio_output);
+      break;
+
+    case PROP_COLOR_OUTPUT:
+      g_value_set_object (value, private->color_output);
+      break;
+
+    case PROP_ANGLE_OUTPUT:
+      g_value_set_object (value, private->angle_output);
+      break;
+
+    case PROP_JITTER_OUTPUT:
+      g_value_set_object (value, private->jitter_output);
+      break;
+
+    case PROP_SPACING_OUTPUT:
+      g_value_set_object (value, private->spacing_output);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_dynamics_dispatch_properties_changed (GObject     *object,
+                                           guint        n_pspecs,
+                                           GParamSpec **pspecs)
+{
+  gint i;
+
+  G_OBJECT_CLASS (parent_class)->dispatch_properties_changed (object,
+                                                              n_pspecs, pspecs);
+
+  for (i = 0; i < n_pspecs; i++)
+    {
+      if (pspecs[i]->flags & GIMP_CONFIG_PARAM_SERIALIZE)
+        {
+          gimp_data_dirty (GIMP_DATA (object));
+          break;
+        }
+    }
+}
+
+static const gchar *
+gimp_dynamics_get_extension (GimpData *data)
+{
+  return GIMP_DYNAMICS_FILE_EXTENSION;
+}
+
+static void
+gimp_dynamics_copy (GimpData *data,
+                    GimpData *src_data)
+{
+  gimp_data_freeze (data);
+
+  gimp_config_copy (GIMP_CONFIG (src_data),
+                    GIMP_CONFIG (data), 0);
+
+  gimp_data_thaw (data);
+}
+
+
+/*  public functions  */
+
+GimpData *
+gimp_dynamics_new (GimpContext *context,
+                   const gchar *name)
+{
+  g_return_val_if_fail (name != NULL, NULL);
+  g_return_val_if_fail (name[0] != '\0', NULL);
+
+  return g_object_new (GIMP_TYPE_DYNAMICS,
+                       "name", name,
+                       NULL);
+}
+
+GimpData *
+gimp_dynamics_get_standard (GimpContext *context)
+{
+  static GimpData *standard_dynamics = NULL;
+
+  if (! standard_dynamics)
+    {
+      standard_dynamics = gimp_dynamics_new (context, "Standard dynamics");
+
+      gimp_data_clean (standard_dynamics);
+      gimp_data_make_internal (standard_dynamics, "gimp-dynamics-standard");
+
+      g_object_add_weak_pointer (G_OBJECT (standard_dynamics),
+                                 (gpointer *) &standard_dynamics);
+    }
+
+  return standard_dynamics;
+}
+
+GimpDynamicsOutput *
+gimp_dynamics_get_output (GimpDynamics           *dynamics,
+                          GimpDynamicsOutputType  type_id)
+{
+  GimpDynamicsPrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_DYNAMICS (dynamics), NULL);
+
+  private = GET_PRIVATE (dynamics);
+
+  switch (type_id)
+    {
+    case GIMP_DYNAMICS_OUTPUT_OPACITY:
+      return private->opacity_output;
+      break;
+
+    case GIMP_DYNAMICS_OUTPUT_FORCE:
+      return private->force_output;
+      break;
+
+    case GIMP_DYNAMICS_OUTPUT_HARDNESS:
+      return private->hardness_output;
+      break;
+
+    case GIMP_DYNAMICS_OUTPUT_RATE:
+      return private->rate_output;
+      break;
+
+    case GIMP_DYNAMICS_OUTPUT_FLOW:
+      return private->flow_output;
+      break;
+
+    case GIMP_DYNAMICS_OUTPUT_SIZE:
+      return private->size_output;
+      break;
+
+    case GIMP_DYNAMICS_OUTPUT_ASPECT_RATIO:
+      return private->aspect_ratio_output;
+      break;
+
+    case GIMP_DYNAMICS_OUTPUT_COLOR:
+      return private->color_output;
+      break;
+
+    case GIMP_DYNAMICS_OUTPUT_ANGLE:
+      return private->angle_output;
+      break;
+
+    case GIMP_DYNAMICS_OUTPUT_JITTER:
+      return private->jitter_output;
+      break;
+
+    case GIMP_DYNAMICS_OUTPUT_SPACING:
+      return private->spacing_output;
+      break;
+
+    default:
+      g_return_val_if_reached (NULL);
+      break;
+    }
+}
+
+gboolean
+gimp_dynamics_is_output_enabled (GimpDynamics           *dynamics,
+                                 GimpDynamicsOutputType  type)
+{
+  GimpDynamicsOutput *output;
+
+  g_return_val_if_fail (GIMP_IS_DYNAMICS (dynamics), FALSE);
+
+  output = gimp_dynamics_get_output (dynamics, type);
+
+  return gimp_dynamics_output_is_enabled (output);
+}
+
+gdouble
+gimp_dynamics_get_linear_value (GimpDynamics           *dynamics,
+                                GimpDynamicsOutputType  type,
+                                const GimpCoords       *coords,
+                                GimpPaintOptions       *options,
+                                gdouble                 fade_point)
+{
+  GimpDynamicsOutput *output;
+
+  g_return_val_if_fail (GIMP_IS_DYNAMICS (dynamics), 0.0);
+
+  output = gimp_dynamics_get_output (dynamics, type);
+
+  return gimp_dynamics_output_get_linear_value (output, coords,
+                                                options, fade_point);
+}
+
+gdouble
+gimp_dynamics_get_angular_value (GimpDynamics           *dynamics,
+                                 GimpDynamicsOutputType  type,
+                                 const GimpCoords       *coords,
+                                 GimpPaintOptions       *options,
+                                 gdouble                 fade_point)
+{
+  GimpDynamicsOutput *output;
+
+  g_return_val_if_fail (GIMP_IS_DYNAMICS (dynamics), 0.0);
+
+  output = gimp_dynamics_get_output (dynamics, type);
+
+  return gimp_dynamics_output_get_angular_value (output, coords,
+                                                 options, fade_point);
+}
+
+gdouble
+gimp_dynamics_get_aspect_value (GimpDynamics           *dynamics,
+                                GimpDynamicsOutputType  type,
+                                const GimpCoords       *coords,
+                                GimpPaintOptions       *options,
+                                gdouble                 fade_point)
+{
+  GimpDynamicsOutput *output;
+
+  g_return_val_if_fail (GIMP_IS_DYNAMICS (dynamics), 0.0);
+
+  output = gimp_dynamics_get_output (dynamics, type);
+
+  return gimp_dynamics_output_get_aspect_value (output, coords,
+                                                options, fade_point);
+}
+
+
+/*  private functions  */
+
+static GimpDynamicsOutput *
+gimp_dynamics_create_output (GimpDynamics           *dynamics,
+                             const gchar            *name,
+                             GimpDynamicsOutputType  type)
+{
+  GimpDynamicsOutput *output = gimp_dynamics_output_new (name, type);
+
+  g_signal_connect (output, "notify",
+                    G_CALLBACK (gimp_dynamics_output_notify),
+                    dynamics);
+
+  return output;
+}
+
+static void
+gimp_dynamics_output_notify (GObject          *output,
+                             const GParamSpec *pspec,
+                             GimpDynamics     *dynamics)
+{
+  g_object_notify (G_OBJECT (dynamics), gimp_object_get_name (output));
+}
diff --git a/app/core/gimpdynamics.h b/app/core/gimpdynamics.h
new file mode 100644
index 0000000..e65fdf6
--- /dev/null
+++ b/app/core/gimpdynamics.h
@@ -0,0 +1,77 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1999 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_DYNAMICS_H__
+#define __GIMP_DYNAMICS_H__
+
+
+#include "gimpdata.h"
+
+
+#define GIMP_TYPE_DYNAMICS            (gimp_dynamics_get_type ())
+#define GIMP_DYNAMICS(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_DYNAMICS, GimpDynamics))
+#define GIMP_DYNAMICS_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_DYNAMICS, GimpDynamicsClass))
+#define GIMP_IS_DYNAMICS(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_DYNAMICS))
+#define GIMP_IS_DYNAMICS_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_DYNAMICS))
+#define GIMP_DYNAMICS_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_DYNAMICS, GimpDynamicsClass))
+
+
+typedef struct _GimpDynamicsClass GimpDynamicsClass;
+
+struct _GimpDynamics
+{
+  GimpData  parent_instance;
+};
+
+struct _GimpDynamicsClass
+{
+  GimpDataClass  parent_class;
+};
+
+
+GType                gimp_dynamics_get_type     (void) G_GNUC_CONST;
+
+GimpData           * gimp_dynamics_new          (GimpContext            *context,
+                                                 const gchar            *name);
+GimpData           * gimp_dynamics_get_standard (GimpContext            *context);
+
+GimpDynamicsOutput * gimp_dynamics_get_output   (GimpDynamics           *dynamics,
+                                                 GimpDynamicsOutputType  type);
+
+gboolean        gimp_dynamics_is_output_enabled (GimpDynamics           *dynamics,
+                                                 GimpDynamicsOutputType  type);
+
+gdouble         gimp_dynamics_get_linear_value  (GimpDynamics           *dynamics,
+                                                 GimpDynamicsOutputType  type,
+                                                 const GimpCoords       *coords,
+                                                 GimpPaintOptions       *options,
+                                                 gdouble                 fade_point);
+
+gdouble         gimp_dynamics_get_angular_value (GimpDynamics           *dynamics,
+                                                 GimpDynamicsOutputType  type,
+                                                 const GimpCoords       *coords,
+                                                 GimpPaintOptions       *options,
+                                                 gdouble                 fade_point);
+
+gdouble         gimp_dynamics_get_aspect_value  (GimpDynamics           *dynamics,
+                                                 GimpDynamicsOutputType  type,
+                                                 const GimpCoords       *coords,
+                                                 GimpPaintOptions       *options,
+                                                 gdouble                 fade_point);
+
+
+#endif  /*  __GIMP_DYNAMICS_H__  */
diff --git a/app/core/gimpdynamicsoutput.c b/app/core/gimpdynamicsoutput.c
new file mode 100644
index 0000000..7a4f309
--- /dev/null
+++ b/app/core/gimpdynamicsoutput.c
@@ -0,0 +1,767 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1999 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpmath/gimpmath.h"
+#include "libgimpconfig/gimpconfig.h"
+
+#include "core-types.h"
+
+#include "paint/gimppaintoptions.h"
+
+
+#include "gimpcurve.h"
+#include "gimpcurve-map.h"
+
+#include "gimpdynamicsoutput.h"
+
+#include "gimp-intl.h"
+
+
+#define DEFAULT_USE_PRESSURE  FALSE
+#define DEFAULT_USE_VELOCITY  FALSE
+#define DEFAULT_USE_DIRECTION FALSE
+#define DEFAULT_USE_TILT      FALSE
+#define DEFAULT_USE_WHEEL     FALSE
+#define DEFAULT_USE_RANDOM    FALSE
+#define DEFAULT_USE_FADE      FALSE
+
+
+enum
+{
+  PROP_0,
+
+  PROP_TYPE,
+  PROP_USE_PRESSURE,
+  PROP_USE_VELOCITY,
+  PROP_USE_DIRECTION,
+  PROP_USE_TILT,
+  PROP_USE_WHEEL,
+  PROP_USE_RANDOM,
+  PROP_USE_FADE,
+  PROP_PRESSURE_CURVE,
+  PROP_VELOCITY_CURVE,
+  PROP_DIRECTION_CURVE,
+  PROP_TILT_CURVE,
+  PROP_WHEEL_CURVE,
+  PROP_RANDOM_CURVE,
+  PROP_FADE_CURVE
+};
+
+
+typedef struct _GimpDynamicsOutputPrivate GimpDynamicsOutputPrivate;
+
+struct _GimpDynamicsOutputPrivate
+{
+  GimpDynamicsOutputType  type;
+
+  gboolean                use_pressure;
+  gboolean                use_velocity;
+  gboolean                use_direction;
+  gboolean                use_tilt;
+  gboolean                use_wheel;
+  gboolean                use_random;
+  gboolean                use_fade;
+
+  GimpCurve              *pressure_curve;
+  GimpCurve              *velocity_curve;
+  GimpCurve              *direction_curve;
+  GimpCurve              *tilt_curve;
+  GimpCurve              *wheel_curve;
+  GimpCurve              *random_curve;
+  GimpCurve              *fade_curve;
+};
+
+#define GET_PRIVATE(output) \
+        ((GimpDynamicsOutputPrivate *) gimp_dynamics_output_get_instance_private ((GimpDynamicsOutput *) (output)))
+
+
+static void   gimp_dynamics_output_finalize     (GObject           *object);
+static void   gimp_dynamics_output_set_property (GObject           *object,
+                                                 guint              property_id,
+                                                 const GValue      *value,
+                                                 GParamSpec        *pspec);
+static void   gimp_dynamics_output_get_property (GObject           *object,
+                                                 guint              property_id,
+                                                 GValue            *value,
+                                                 GParamSpec        *pspec);
+static void   gimp_dynamics_output_copy_curve   (GimpCurve          *src,
+                                                 GimpCurve          *dest);
+
+static GimpCurve *
+              gimp_dynamics_output_create_curve (GimpDynamicsOutput *output,
+                                                 const gchar        *name);
+static void   gimp_dynamics_output_curve_dirty  (GimpCurve          *curve,
+                                                 GimpDynamicsOutput *output);
+
+
+G_DEFINE_TYPE_WITH_CODE (GimpDynamicsOutput, gimp_dynamics_output,
+                         GIMP_TYPE_OBJECT,
+                         G_ADD_PRIVATE (GimpDynamicsOutput)
+                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_CONFIG, NULL))
+
+#define parent_class gimp_dynamics_output_parent_class
+
+
+static void
+gimp_dynamics_output_class_init (GimpDynamicsOutputClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  object_class->finalize     = gimp_dynamics_output_finalize;
+  object_class->set_property = gimp_dynamics_output_set_property;
+  object_class->get_property = gimp_dynamics_output_get_property;
+
+  g_object_class_install_property (object_class, PROP_TYPE,
+                                   g_param_spec_enum ("type", NULL,
+                                                      _("Output type"),
+                                                      GIMP_TYPE_DYNAMICS_OUTPUT_TYPE,
+                                                      GIMP_DYNAMICS_OUTPUT_OPACITY,
+                                                      GIMP_PARAM_READWRITE |
+                                                      G_PARAM_CONSTRUCT));
+
+  GIMP_CONFIG_PROP_BOOLEAN (object_class, PROP_USE_PRESSURE,
+                            "use-pressure",
+                            NULL, NULL,
+                            DEFAULT_USE_PRESSURE,
+                            GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_BOOLEAN (object_class, PROP_USE_VELOCITY,
+                            "use-velocity",
+                            NULL, NULL,
+                            DEFAULT_USE_VELOCITY,
+                            GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_BOOLEAN (object_class, PROP_USE_DIRECTION,
+                            "use-direction",
+                            NULL, NULL,
+                            DEFAULT_USE_DIRECTION,
+                            GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_BOOLEAN (object_class, PROP_USE_TILT,
+                            "use-tilt",
+                            NULL, NULL,
+                            DEFAULT_USE_TILT,
+                            GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_BOOLEAN (object_class, PROP_USE_WHEEL,
+                            "use-wheel",
+                            NULL, NULL,
+                            DEFAULT_USE_TILT,
+                            GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_BOOLEAN (object_class, PROP_USE_RANDOM,
+                            "use-random",
+                            NULL, NULL,
+                            DEFAULT_USE_RANDOM,
+                            GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_BOOLEAN (object_class, PROP_USE_FADE,
+                            "use-fade",
+                            NULL, NULL,
+                            DEFAULT_USE_FADE,
+                            GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_OBJECT (object_class, PROP_PRESSURE_CURVE,
+                           "pressure-curve",
+                            NULL, NULL,
+                           GIMP_TYPE_CURVE,
+                           GIMP_CONFIG_PARAM_AGGREGATE);
+
+  GIMP_CONFIG_PROP_OBJECT (object_class, PROP_VELOCITY_CURVE,
+                           "velocity-curve",
+                            NULL, NULL,
+                           GIMP_TYPE_CURVE,
+                           GIMP_CONFIG_PARAM_AGGREGATE);
+
+  GIMP_CONFIG_PROP_OBJECT (object_class, PROP_DIRECTION_CURVE,
+                           "direction-curve",
+                            NULL, NULL,
+                           GIMP_TYPE_CURVE,
+                           GIMP_CONFIG_PARAM_AGGREGATE);
+
+  GIMP_CONFIG_PROP_OBJECT (object_class, PROP_TILT_CURVE,
+                           "tilt-curve",
+                            NULL, NULL,
+                           GIMP_TYPE_CURVE,
+                           GIMP_CONFIG_PARAM_AGGREGATE);
+
+  GIMP_CONFIG_PROP_OBJECT (object_class, PROP_WHEEL_CURVE,
+                           "wheel-curve",
+                            NULL, NULL,
+                           GIMP_TYPE_CURVE,
+                           GIMP_CONFIG_PARAM_AGGREGATE);
+
+  GIMP_CONFIG_PROP_OBJECT (object_class, PROP_RANDOM_CURVE,
+                           "random-curve",
+                            NULL, NULL,
+                           GIMP_TYPE_CURVE,
+                           GIMP_CONFIG_PARAM_AGGREGATE);
+
+  GIMP_CONFIG_PROP_OBJECT (object_class, PROP_FADE_CURVE,
+                           "fade-curve",
+                            NULL, NULL,
+                           GIMP_TYPE_CURVE,
+                           GIMP_CONFIG_PARAM_AGGREGATE);
+}
+
+static void
+gimp_dynamics_output_init (GimpDynamicsOutput *output)
+{
+  GimpDynamicsOutputPrivate *private = GET_PRIVATE (output);
+
+  private->pressure_curve  = gimp_dynamics_output_create_curve (output,
+                                                                "pressure-curve");
+  private->velocity_curve  = gimp_dynamics_output_create_curve (output,
+                                                                "velocity-curve");
+  private->direction_curve = gimp_dynamics_output_create_curve (output,
+                                                                "direction-curve");
+  private->tilt_curve      = gimp_dynamics_output_create_curve (output,
+                                                                "tilt-curve");
+  private->wheel_curve     = gimp_dynamics_output_create_curve (output,
+                                                                "wheel-curve");
+  private->random_curve    = gimp_dynamics_output_create_curve (output,
+                                                                "random-curve");
+  private->fade_curve      = gimp_dynamics_output_create_curve (output,
+                                                                "fade-curve");
+}
+
+static void
+gimp_dynamics_output_finalize (GObject *object)
+{
+  GimpDynamicsOutputPrivate *private = GET_PRIVATE (object);
+
+  g_clear_object (&private->pressure_curve);
+  g_clear_object (&private->velocity_curve);
+  g_clear_object (&private->direction_curve);
+  g_clear_object (&private->tilt_curve);
+  g_clear_object (&private->wheel_curve);
+  g_clear_object (&private->random_curve);
+  g_clear_object (&private->fade_curve);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gimp_dynamics_output_set_property (GObject      *object,
+                                   guint         property_id,
+                                   const GValue *value,
+                                   GParamSpec   *pspec)
+{
+  GimpDynamicsOutputPrivate *private = GET_PRIVATE (object);
+
+  switch (property_id)
+    {
+    case PROP_TYPE:
+      private->type = g_value_get_enum (value);
+      break;
+
+    case PROP_USE_PRESSURE:
+      private->use_pressure = g_value_get_boolean (value);
+      break;
+
+    case PROP_USE_VELOCITY:
+      private->use_velocity = g_value_get_boolean (value);
+      break;
+
+    case PROP_USE_DIRECTION:
+      private->use_direction = g_value_get_boolean (value);
+      break;
+
+    case PROP_USE_TILT:
+      private->use_tilt = g_value_get_boolean (value);
+      break;
+
+    case PROP_USE_WHEEL:
+      private->use_wheel = g_value_get_boolean (value);
+      break;
+
+    case PROP_USE_RANDOM:
+      private->use_random = g_value_get_boolean (value);
+      break;
+
+    case PROP_USE_FADE:
+      private->use_fade = g_value_get_boolean (value);
+      break;
+
+    case PROP_PRESSURE_CURVE:
+      gimp_dynamics_output_copy_curve (g_value_get_object (value),
+                                       private->pressure_curve);
+      break;
+
+    case PROP_VELOCITY_CURVE:
+      gimp_dynamics_output_copy_curve (g_value_get_object (value),
+                                       private->velocity_curve);
+      break;
+
+    case PROP_DIRECTION_CURVE:
+      gimp_dynamics_output_copy_curve (g_value_get_object (value),
+                                       private->direction_curve);
+      break;
+
+    case PROP_TILT_CURVE:
+      gimp_dynamics_output_copy_curve (g_value_get_object (value),
+                                       private->tilt_curve);
+      break;
+
+    case PROP_WHEEL_CURVE:
+      gimp_dynamics_output_copy_curve (g_value_get_object (value),
+                                       private->wheel_curve);
+      break;
+
+    case PROP_RANDOM_CURVE:
+      gimp_dynamics_output_copy_curve (g_value_get_object (value),
+                                       private->random_curve);
+      break;
+
+    case PROP_FADE_CURVE:
+      gimp_dynamics_output_copy_curve (g_value_get_object (value),
+                                       private->fade_curve);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_dynamics_output_get_property (GObject    *object,
+                                   guint       property_id,
+                                   GValue     *value,
+                                   GParamSpec *pspec)
+{
+  GimpDynamicsOutputPrivate *private = GET_PRIVATE (object);
+
+  switch (property_id)
+    {
+    case PROP_TYPE:
+      g_value_set_enum (value, private->type);
+      break;
+
+    case PROP_USE_PRESSURE:
+      g_value_set_boolean (value, private->use_pressure);
+      break;
+
+    case PROP_USE_VELOCITY:
+      g_value_set_boolean (value, private->use_velocity);
+      break;
+
+    case PROP_USE_DIRECTION:
+      g_value_set_boolean (value, private->use_direction);
+      break;
+
+    case PROP_USE_TILT:
+      g_value_set_boolean (value, private->use_tilt);
+      break;
+
+    case PROP_USE_WHEEL:
+      g_value_set_boolean (value, private->use_wheel);
+      break;
+
+    case PROP_USE_RANDOM:
+      g_value_set_boolean (value, private->use_random);
+      break;
+
+    case PROP_USE_FADE:
+      g_value_set_boolean (value, private->use_fade);
+      break;
+
+    case PROP_PRESSURE_CURVE:
+      g_value_set_object (value, private->pressure_curve);
+      break;
+
+    case PROP_VELOCITY_CURVE:
+      g_value_set_object (value, private->velocity_curve);
+      break;
+
+    case PROP_DIRECTION_CURVE:
+      g_value_set_object (value, private->direction_curve);
+      break;
+
+    case PROP_TILT_CURVE:
+      g_value_set_object (value, private->tilt_curve);
+      break;
+
+    case PROP_WHEEL_CURVE:
+      g_value_set_object (value, private->wheel_curve);
+      break;
+
+    case PROP_RANDOM_CURVE:
+      g_value_set_object (value, private->random_curve);
+      break;
+
+    case PROP_FADE_CURVE:
+      g_value_set_object (value, private->fade_curve);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+
+/*  public functions  */
+
+GimpDynamicsOutput *
+gimp_dynamics_output_new (const gchar            *name,
+                          GimpDynamicsOutputType  type)
+{
+  g_return_val_if_fail (name != NULL, NULL);
+
+  return g_object_new (GIMP_TYPE_DYNAMICS_OUTPUT,
+                       "name", name,
+                       "type", type,
+                       NULL);
+}
+
+gboolean
+gimp_dynamics_output_is_enabled (GimpDynamicsOutput *output)
+{
+  GimpDynamicsOutputPrivate *private = GET_PRIVATE (output);
+
+  return (private->use_pressure  ||
+          private->use_velocity  ||
+          private->use_direction ||
+          private->use_tilt      ||
+          private->use_wheel     ||
+          private->use_random    ||
+          private->use_fade);
+}
+
+gdouble
+gimp_dynamics_output_get_linear_value (GimpDynamicsOutput *output,
+                                       const GimpCoords   *coords,
+                                       GimpPaintOptions   *options,
+                                       gdouble             fade_point)
+{
+  GimpDynamicsOutputPrivate *private = GET_PRIVATE (output);
+  gdouble                    total   = 0.0;
+  gdouble                    result  = 1.0;
+  gint                       factors = 0;
+
+  if (private->use_pressure)
+    {
+      total += gimp_curve_map_value (private->pressure_curve,
+                                     coords->pressure);
+      factors++;
+    }
+
+  if (private->use_velocity)
+    {
+      total += gimp_curve_map_value (private->velocity_curve,
+                                    (1.0 - coords->velocity));
+      factors++;
+    }
+
+  if (private->use_direction)
+    {
+      total += gimp_curve_map_value (private->direction_curve,
+                                     fmod (coords->direction + 0.5, 1));
+      factors++;
+    }
+
+  if (private->use_tilt)
+    {
+      total += gimp_curve_map_value (private->tilt_curve,
+                                     (1.0 - sqrt (SQR (coords->xtilt) +
+                                      SQR (coords->ytilt))));
+      factors++;
+    }
+
+  if (private->use_wheel)
+    {
+      gdouble wheel;
+
+      wheel = coords->wheel;
+
+      total += gimp_curve_map_value (private->wheel_curve, wheel);
+      factors++;
+    }
+
+  if (private->use_random)
+    {
+      total += gimp_curve_map_value (private->random_curve,
+                                     g_random_double_range (0.0, 1.0));
+      factors++;
+    }
+
+  if (private->use_fade)
+    {
+      total += gimp_curve_map_value (private->fade_curve, fade_point);
+
+      factors++;
+    }
+
+  if (factors > 0)
+    result = total / factors;
+
+#if 0
+  g_printerr ("Dynamics queried(linear). Result: %f, factors: %d, total: %f\n",
+              result, factors, total);
+#endif
+
+  return result;
+}
+
+gdouble
+gimp_dynamics_output_get_angular_value (GimpDynamicsOutput *output,
+                                        const GimpCoords   *coords,
+                                        GimpPaintOptions   *options,
+                                        gdouble             fade_point)
+{
+  GimpDynamicsOutputPrivate *private = GET_PRIVATE (output);
+  gdouble                    total   = 0.0;
+  gdouble                    result  = 0.0; /* angles are additive, so we return zero for no change. */
+  gint                       factors = 0;
+
+  if (private->use_pressure)
+    {
+      total += gimp_curve_map_value (private->pressure_curve,
+                                     coords->pressure);
+      factors++;
+    }
+
+  if (private->use_velocity)
+    {
+      total += gimp_curve_map_value (private->velocity_curve,
+                                    (1.0 - coords->velocity));
+      factors++;
+    }
+
+  if (private->use_direction)
+    {
+      gdouble angle = gimp_curve_map_value (private->direction_curve,
+                                            coords->direction);
+
+      if (options->brush_lock_to_view)
+        {
+          if (coords->reflect)
+            angle = 0.5 - angle;
+
+          angle -= coords->angle;
+          angle  = fmod (fmod (angle, 1.0) + 1.0, 1.0);
+        }
+
+      total += angle;
+      factors++;
+    }
+
+  /* For tilt to make sense, it needs to be converted to an angle, not
+   * just a vector
+   */
+  if (private->use_tilt)
+    {
+      gdouble tilt_x = coords->xtilt;
+      gdouble tilt_y = coords->ytilt;
+      gdouble tilt   = 0.0;
+
+      if (tilt_x == 0.0)
+        {
+          if (tilt_y > 0.0)
+            tilt = 0.25;
+          else if (tilt_y < 0.0)
+            tilt = 0.75;
+          else
+            tilt = 0.0;
+        }
+      else
+        {
+          tilt = atan ((- 1.0 * tilt_y) /
+                                tilt_x) / (2 * G_PI);
+
+          if (tilt_x > 0.0)
+            tilt = tilt + 0.5;
+        }
+
+      tilt = tilt + 0.5; /* correct the angle, its wrong by 180 degrees */
+
+      while (tilt > 1.0)
+        tilt -= 1.0;
+
+      while (tilt < 0.0)
+        tilt += 1.0;
+
+      total += gimp_curve_map_value (private->tilt_curve, tilt);
+      factors++;
+    }
+
+  if (private->use_wheel)
+    {
+      gdouble angle = 1.0 - fmod(0.5 + coords->wheel, 1);
+
+      total += gimp_curve_map_value (private->wheel_curve, angle);
+      factors++;
+    }
+
+  if (private->use_random)
+    {
+      total += gimp_curve_map_value (private->random_curve,
+                                     g_random_double_range (0.0, 1.0));
+      factors++;
+    }
+
+  if (private->use_fade)
+    {
+      total += gimp_curve_map_value (private->fade_curve, fade_point);
+
+      factors++;
+    }
+
+  if (factors > 0)
+    result = total / factors;
+
+#if 0
+  g_printerr ("Dynamics queried(angle). Result: %f, factors: %d, total: %f\n",
+              result, factors, total);
+#endif
+
+   return result;
+}
+
+gdouble
+gimp_dynamics_output_get_aspect_value (GimpDynamicsOutput *output,
+                                       const GimpCoords   *coords,
+                                       GimpPaintOptions   *options,
+                                       gdouble             fade_point)
+{
+  GimpDynamicsOutputPrivate *private = GET_PRIVATE (output);
+  gdouble                    total   = 0.0;
+  gint                       factors = 0;
+  gdouble                    sign    = 1.0;
+  gdouble                    result  = 1.0;
+
+  if (private->use_pressure)
+    {
+      total += gimp_curve_map_value (private->pressure_curve,
+                                     coords->pressure);
+      factors++;
+    }
+
+  if (private->use_velocity)
+    {
+      total += gimp_curve_map_value (private->velocity_curve,
+                                     coords->velocity);
+      factors++;
+    }
+
+  if (private->use_direction)
+    {
+      gdouble direction = gimp_curve_map_value (private->direction_curve,
+                                                coords->direction);
+
+      if (((direction > 0.875) && (direction <= 1.0)) ||
+          ((direction > 0.0) && (direction < 0.125))  ||
+          ((direction > 0.375) && (direction < 0.625)))
+        sign = -1.0;
+
+      total += 1.0;
+      factors++;
+    }
+
+  if (private->use_tilt)
+    {
+      gdouble tilt_value =  MAX (fabs (coords->xtilt), fabs (coords->ytilt));
+
+      tilt_value = gimp_curve_map_value (private->tilt_curve,
+                                         tilt_value);
+
+      total += tilt_value;
+
+      factors++;
+    }
+
+  if (private->use_wheel)
+    {
+      gdouble wheel = gimp_curve_map_value (private->wheel_curve,
+                                            coords->wheel);
+
+      if (((wheel > 0.875) && (wheel <= 1.0)) ||
+          ((wheel > 0.0) && (wheel < 0.125))  ||
+          ((wheel > 0.375) && (wheel < 0.625)))
+        sign = -1.0;
+
+      total += 1.0;
+      factors++;
+
+    }
+
+  if (private->use_random)
+    {
+      gdouble random = gimp_curve_map_value (private->random_curve,
+                                             g_random_double_range (0.0, 1.0));
+
+      total += random;
+      factors++;
+    }
+
+  if (private->use_fade)
+    {
+      total += gimp_curve_map_value (private->fade_curve, fade_point);
+
+      factors++;
+    }
+
+  if (factors > 0)
+    result = total / factors;
+
+
+#if 0
+  g_printerr ("Dynamics queried(aspect). Result: %f, factors: %d, total: %f sign: %f\n",
+              result, factors, total, sign);
+#endif
+  result = CLAMP (result * sign, -1.0, 1.0);
+
+  return result;
+}
+
+static void
+gimp_dynamics_output_copy_curve (GimpCurve *src,
+                                 GimpCurve *dest)
+{
+  if (src && dest)
+    {
+      gimp_config_copy (GIMP_CONFIG (src),
+                        GIMP_CONFIG (dest),
+                        GIMP_CONFIG_PARAM_SERIALIZE);
+    }
+}
+
+static GimpCurve *
+gimp_dynamics_output_create_curve (GimpDynamicsOutput *output,
+                                   const gchar        *name)
+{
+  GimpCurve *curve = GIMP_CURVE (gimp_curve_new (name));
+
+  g_signal_connect_object (curve, "dirty",
+                           G_CALLBACK (gimp_dynamics_output_curve_dirty),
+                           output, 0);
+
+  return curve;
+}
+
+static void
+gimp_dynamics_output_curve_dirty (GimpCurve          *curve,
+                                  GimpDynamicsOutput *output)
+{
+  g_object_notify (G_OBJECT (output), gimp_object_get_name (curve));
+}
diff --git a/app/core/gimpdynamicsoutput.h b/app/core/gimpdynamicsoutput.h
new file mode 100644
index 0000000..855cc4a
--- /dev/null
+++ b/app/core/gimpdynamicsoutput.h
@@ -0,0 +1,68 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1999 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_DYNAMICS_OUTPUT_H__
+#define __GIMP_DYNAMICS_OUTPUT_H__
+
+
+#include "gimpobject.h"
+
+
+#define GIMP_TYPE_DYNAMICS_OUTPUT            (gimp_dynamics_output_get_type ())
+#define GIMP_DYNAMICS_OUTPUT(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_DYNAMICS_OUTPUT, GimpDynamicsOutput))
+#define GIMP_DYNAMICS_OUTPUT_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_DYNAMICS_OUTPUT, GimpDynamicsOutputClass))
+#define GIMP_IS_DYNAMICS_OUTPUT(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_DYNAMICS_OUTPUT))
+#define GIMP_IS_DYNAMICS_OUTPUT_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_DYNAMICS_OUTPUT))
+#define GIMP_DYNAMICS_OUTPUT_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_DYNAMICS_OUTPUT, GimpDynamicsOutputClass))
+
+
+typedef struct _GimpDynamicsOutputClass GimpDynamicsOutputClass;
+
+struct _GimpDynamicsOutput
+{
+  GimpObject  parent_instance;
+};
+
+struct _GimpDynamicsOutputClass
+{
+  GimpObjectClass  parent_class;
+};
+
+
+GType                gimp_dynamics_output_get_type (void) G_GNUC_CONST;
+
+GimpDynamicsOutput * gimp_dynamics_output_new      (const gchar            *name,
+                                                    GimpDynamicsOutputType  type);
+
+gboolean   gimp_dynamics_output_is_enabled         (GimpDynamicsOutput *output);
+
+gdouble    gimp_dynamics_output_get_linear_value   (GimpDynamicsOutput *output,
+                                                    const GimpCoords   *coords,
+                                                    GimpPaintOptions   *options,
+                                                    gdouble             fade_point);
+
+gdouble    gimp_dynamics_output_get_angular_value  (GimpDynamicsOutput *output,
+                                                    const GimpCoords   *coords,
+                                                    GimpPaintOptions   *options,
+                                                    gdouble             fade_point);
+gdouble    gimp_dynamics_output_get_aspect_value   (GimpDynamicsOutput *output,
+                                                    const GimpCoords   *coords,
+                                                    GimpPaintOptions   *options,
+                                                    gdouble             fade_point);
+
+
+#endif  /*  __GIMP_DYNAMICS_OUTPUT_H__  */
diff --git a/app/core/gimperror.c b/app/core/gimperror.c
new file mode 100644
index 0000000..29394cb
--- /dev/null
+++ b/app/core/gimperror.c
@@ -0,0 +1,36 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <glib-object.h>
+
+#include "gimperror.h"
+
+
+/**
+ * gimp_error_quark:
+ *
+ * This function is never called directly. Use GIMP_ERROR() instead.
+ *
+ * Return value: the #GQuark that defines the general GIMP error domain.
+ **/
+GQuark
+gimp_error_quark (void)
+{
+  return g_quark_from_static_string ("gimp-error-quark");
+}
diff --git a/app/core/gimperror.h b/app/core/gimperror.h
new file mode 100644
index 0000000..f8088ec
--- /dev/null
+++ b/app/core/gimperror.h
@@ -0,0 +1,33 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_ERROR_H__
+#define __GIMP_ERROR_H__
+
+
+typedef enum
+{
+  GIMP_FAILED,  /* generic error condition */
+} GimpErrorCode;
+
+
+#define GIMP_ERROR (gimp_error_quark ())
+
+GQuark  gimp_error_quark (void) G_GNUC_CONST;
+
+
+#endif /* __GIMP_ERROR_H__ */
diff --git a/app/core/gimpfilloptions.c b/app/core/gimpfilloptions.c
new file mode 100644
index 0000000..d10b6e4
--- /dev/null
+++ b/app/core/gimpfilloptions.c
@@ -0,0 +1,548 @@
+/* The GIMP -- an image manipulation program
+ * Copyright (C) 1995-1999 Spencer Kimball and Peter Mattis
+ *
+ * gimpfilloptions.c
+ * Copyright (C) 2003 Simon Budig
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <cairo.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpcolor/gimpcolor.h"
+#include "libgimpconfig/gimpconfig.h"
+
+#include "core-types.h"
+
+#include "operations/layer-modes/gimp-layer-modes.h"
+
+#include "gimp.h"
+#include "gimp-palettes.h"
+#include "gimpdrawable.h"
+#include "gimpdrawable-fill.h"
+#include "gimperror.h"
+#include "gimpfilloptions.h"
+#include "gimppattern.h"
+
+#include "gimp-intl.h"
+
+
+enum
+{
+  PROP_0,
+  PROP_STYLE,
+  PROP_ANTIALIAS,
+  PROP_FEATHER,
+  PROP_FEATHER_RADIUS,
+  PROP_PATTERN_VIEW_TYPE,
+  PROP_PATTERN_VIEW_SIZE
+};
+
+
+typedef struct _GimpFillOptionsPrivate GimpFillOptionsPrivate;
+
+struct _GimpFillOptionsPrivate
+{
+  GimpFillStyle style;
+  gboolean      antialias;
+  gboolean      feather;
+  gdouble       feather_radius;
+
+  GimpViewType  pattern_view_type;
+  GimpViewSize  pattern_view_size;
+
+  const gchar  *undo_desc;
+};
+
+#define GET_PRIVATE(options) \
+        ((GimpFillOptionsPrivate *) gimp_fill_options_get_instance_private ((GimpFillOptions *) (options)))
+
+
+static void     gimp_fill_options_config_init  (GimpConfigInterface *iface);
+
+static void     gimp_fill_options_set_property (GObject             *object,
+                                                guint                property_id,
+                                                const GValue        *value,
+                                                GParamSpec          *pspec);
+static void     gimp_fill_options_get_property (GObject             *object,
+                                                guint                property_id,
+                                                GValue              *value,
+                                                GParamSpec          *pspec);
+
+static gboolean gimp_fill_options_serialize    (GimpConfig          *config,
+                                                GimpConfigWriter    *writer,
+                                                gpointer             data);
+
+
+G_DEFINE_TYPE_WITH_CODE (GimpFillOptions, gimp_fill_options, GIMP_TYPE_CONTEXT,
+                         G_ADD_PRIVATE (GimpFillOptions)
+                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_CONFIG,
+                                                gimp_fill_options_config_init))
+
+
+static void
+gimp_fill_options_class_init (GimpFillOptionsClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  object_class->set_property = gimp_fill_options_set_property;
+  object_class->get_property = gimp_fill_options_get_property;
+
+  GIMP_CONFIG_PROP_ENUM (object_class, PROP_STYLE,
+                         "style",
+                         _("Style"),
+                         NULL,
+                         GIMP_TYPE_FILL_STYLE,
+                         GIMP_FILL_STYLE_SOLID,
+                         GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_BOOLEAN (object_class, PROP_ANTIALIAS,
+                            "antialias",
+                            _("Antialiasing"),
+                            NULL,
+                            TRUE,
+                            GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_BOOLEAN (object_class, PROP_FEATHER,
+                            "feather",
+                            _("Feather edges"),
+                            _("Enable feathering of fill edges"),
+                            FALSE,
+                            GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_DOUBLE (object_class, PROP_FEATHER_RADIUS,
+                           "feather-radius",
+                           _("Radius"),
+                           _("Radius of feathering"),
+                           0.0, 100.0, 10.0,
+                           GIMP_PARAM_STATIC_STRINGS);
+
+  g_object_class_install_property (object_class, PROP_PATTERN_VIEW_TYPE,
+                                   g_param_spec_enum ("pattern-view-type",
+                                                      NULL, NULL,
+                                                      GIMP_TYPE_VIEW_TYPE,
+                                                      GIMP_VIEW_TYPE_GRID,
+                                                      G_PARAM_CONSTRUCT |
+                                                      GIMP_PARAM_READWRITE));
+
+  g_object_class_install_property (object_class, PROP_PATTERN_VIEW_SIZE,
+                                   g_param_spec_int ("pattern-view-size",
+                                                     NULL, NULL,
+                                                     GIMP_VIEW_SIZE_TINY,
+                                                     GIMP_VIEWABLE_MAX_BUTTON_SIZE,
+                                                     GIMP_VIEW_SIZE_SMALL,
+                                                     G_PARAM_CONSTRUCT |
+                                                     GIMP_PARAM_READWRITE));
+}
+
+static void
+gimp_fill_options_config_init (GimpConfigInterface *iface)
+{
+  iface->serialize = gimp_fill_options_serialize;
+}
+
+static void
+gimp_fill_options_init (GimpFillOptions *options)
+{
+}
+
+static void
+gimp_fill_options_set_property (GObject      *object,
+                                guint         property_id,
+                                const GValue *value,
+                                GParamSpec   *pspec)
+{
+  GimpFillOptionsPrivate *private = GET_PRIVATE (object);
+
+  switch (property_id)
+    {
+    case PROP_STYLE:
+      private->style = g_value_get_enum (value);
+      private->undo_desc = NULL;
+      break;
+    case PROP_ANTIALIAS:
+      private->antialias = g_value_get_boolean (value);
+      break;
+    case PROP_FEATHER:
+      private->feather = g_value_get_boolean (value);
+      break;
+    case PROP_FEATHER_RADIUS:
+      private->feather_radius = g_value_get_double (value);
+      break;
+
+    case PROP_PATTERN_VIEW_TYPE:
+      private->pattern_view_type = g_value_get_enum (value);
+      break;
+    case PROP_PATTERN_VIEW_SIZE:
+      private->pattern_view_size = g_value_get_int (value);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_fill_options_get_property (GObject    *object,
+                                guint       property_id,
+                                GValue     *value,
+                                GParamSpec *pspec)
+{
+  GimpFillOptionsPrivate *private = GET_PRIVATE (object);
+
+  switch (property_id)
+    {
+    case PROP_STYLE:
+      g_value_set_enum (value, private->style);
+      break;
+    case PROP_ANTIALIAS:
+      g_value_set_boolean (value, private->antialias);
+      break;
+    case PROP_FEATHER:
+      g_value_set_boolean (value, private->feather);
+      break;
+    case PROP_FEATHER_RADIUS:
+      g_value_set_double (value, private->feather_radius);
+      break;
+
+    case PROP_PATTERN_VIEW_TYPE:
+      g_value_set_enum (value, private->pattern_view_type);
+      break;
+    case PROP_PATTERN_VIEW_SIZE:
+      g_value_set_int (value, private->pattern_view_size);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static gboolean
+gimp_fill_options_serialize (GimpConfig       *config,
+                             GimpConfigWriter *writer,
+                             gpointer          data)
+{
+  return gimp_config_serialize_properties (config, writer);
+}
+
+
+/*  public functions  */
+
+GimpFillOptions *
+gimp_fill_options_new (Gimp        *gimp,
+                       GimpContext *context,
+                       gboolean     use_context_color)
+{
+  GimpFillOptions *options;
+
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+  g_return_val_if_fail (context == NULL || GIMP_IS_CONTEXT (context), NULL);
+  g_return_val_if_fail (use_context_color == FALSE || context != NULL, NULL);
+
+  options = g_object_new (GIMP_TYPE_FILL_OPTIONS,
+                          "gimp", gimp,
+                          NULL);
+
+  if (use_context_color)
+    {
+      gimp_context_define_properties (GIMP_CONTEXT (options),
+                                      GIMP_CONTEXT_PROP_MASK_FOREGROUND |
+                                      GIMP_CONTEXT_PROP_MASK_PATTERN,
+                                      FALSE);
+
+      gimp_context_set_parent (GIMP_CONTEXT (options), context);
+    }
+
+  return options;
+}
+
+GimpFillStyle
+gimp_fill_options_get_style (GimpFillOptions *options)
+{
+  g_return_val_if_fail (GIMP_IS_FILL_OPTIONS (options), GIMP_FILL_STYLE_SOLID);
+
+  return GET_PRIVATE (options)->style;
+}
+
+void
+gimp_fill_options_set_style (GimpFillOptions *options,
+                             GimpFillStyle    style)
+{
+  g_return_if_fail (GIMP_IS_FILL_OPTIONS (options));
+
+  g_object_set (options, "style", style, NULL);
+}
+
+gboolean
+gimp_fill_options_get_antialias (GimpFillOptions *options)
+{
+  g_return_val_if_fail (GIMP_IS_FILL_OPTIONS (options), FALSE);
+
+  return GET_PRIVATE (options)->antialias;
+}
+
+void
+gimp_fill_options_set_antialias (GimpFillOptions *options,
+                                 gboolean         antialias)
+{
+  g_return_if_fail (GIMP_IS_FILL_OPTIONS (options));
+
+  g_object_set (options, "antialias", antialias, NULL);
+}
+
+gboolean
+gimp_fill_options_get_feather (GimpFillOptions *options,
+                               gdouble         *radius)
+{
+  g_return_val_if_fail (GIMP_IS_FILL_OPTIONS (options), FALSE);
+
+  if (radius)
+    *radius = GET_PRIVATE (options)->feather_radius;
+
+  return GET_PRIVATE (options)->feather;
+}
+
+void
+gimp_fill_options_set_feather (GimpFillOptions *options,
+                               gboolean         feather,
+                               gdouble          radius)
+{
+  g_return_if_fail (GIMP_IS_FILL_OPTIONS (options));
+
+  g_object_set (options, "feather", feather, NULL);
+  g_object_set (options, "feather-radius", radius, NULL);
+}
+
+gboolean
+gimp_fill_options_set_by_fill_type (GimpFillOptions  *options,
+                                    GimpContext      *context,
+                                    GimpFillType      fill_type,
+                                    GError          **error)
+{
+  GimpFillOptionsPrivate *private;
+  GimpRGB                 color;
+  const gchar            *undo_desc;
+
+  g_return_val_if_fail (GIMP_IS_FILL_OPTIONS (options), FALSE);
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  private = GET_PRIVATE (options);
+
+  private->undo_desc = NULL;
+
+  switch (fill_type)
+    {
+    case GIMP_FILL_FOREGROUND:
+      gimp_context_get_foreground (context, &color);
+      undo_desc = C_("undo-type", "Fill with Foreground Color");
+      break;
+
+    case GIMP_FILL_BACKGROUND:
+      gimp_context_get_background (context, &color);
+      undo_desc = C_("undo-type", "Fill with Background Color");
+      break;
+
+    case GIMP_FILL_WHITE:
+      gimp_rgba_set (&color, 1.0, 1.0, 1.0, GIMP_OPACITY_OPAQUE);
+      undo_desc = C_("undo-type", "Fill with White");
+      break;
+
+    case GIMP_FILL_TRANSPARENT:
+      gimp_context_get_background (context, &color);
+      gimp_context_set_paint_mode (GIMP_CONTEXT (options),
+                                   GIMP_LAYER_MODE_ERASE);
+      undo_desc = C_("undo-type", "Fill with Transparency");
+      break;
+
+    case GIMP_FILL_PATTERN:
+      {
+        GimpPattern *pattern = gimp_context_get_pattern (context);
+
+        if (! pattern)
+          {
+            g_set_error_literal (error, GIMP_ERROR, GIMP_FAILED,
+                                 _("No patterns available for this operation."));
+            return FALSE;
+          }
+
+        gimp_fill_options_set_style (options, GIMP_FILL_STYLE_PATTERN);
+        gimp_context_set_pattern (GIMP_CONTEXT (options), pattern);
+        private->undo_desc = C_("undo-type", "Fill with Pattern");
+
+        return TRUE;
+      }
+      break;
+
+    default:
+      g_warning ("%s: invalid fill_type %d", G_STRFUNC, fill_type);
+      return FALSE;
+    }
+
+  gimp_fill_options_set_style (options, GIMP_FILL_STYLE_SOLID);
+  gimp_context_set_foreground (GIMP_CONTEXT (options), &color);
+  private->undo_desc = undo_desc;
+
+  return TRUE;
+}
+
+gboolean
+gimp_fill_options_set_by_fill_mode (GimpFillOptions     *options,
+                                    GimpContext         *context,
+                                    GimpBucketFillMode   fill_mode,
+                                    GError             **error)
+{
+  GimpFillType fill_type;
+
+  g_return_val_if_fail (GIMP_IS_FILL_OPTIONS (options), FALSE);
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  switch (fill_mode)
+    {
+    default:
+    case GIMP_BUCKET_FILL_FG:
+      fill_type = GIMP_FILL_FOREGROUND;
+      break;
+
+    case GIMP_BUCKET_FILL_BG:
+      fill_type = GIMP_FILL_BACKGROUND;
+      break;
+
+    case GIMP_BUCKET_FILL_PATTERN:
+      fill_type = GIMP_FILL_PATTERN;
+      break;
+    }
+
+  return gimp_fill_options_set_by_fill_type (options, context,
+                                             fill_type, error);
+}
+
+const gchar *
+gimp_fill_options_get_undo_desc (GimpFillOptions *options)
+{
+  GimpFillOptionsPrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_FILL_OPTIONS (options), NULL);
+
+  private = GET_PRIVATE (options);
+
+  if (private->undo_desc)
+    return private->undo_desc;
+
+  switch (private->style)
+    {
+    case GIMP_FILL_STYLE_SOLID:
+      return C_("undo-type", "Fill with Solid Color");
+
+    case GIMP_FILL_STYLE_PATTERN:
+      return C_("undo-type", "Fill with Pattern");
+    }
+
+  g_return_val_if_reached (NULL);
+}
+
+const Babl *
+gimp_fill_options_get_format (GimpFillOptions *options,
+                              GimpDrawable    *drawable)
+{
+  GimpContext *context;
+
+  g_return_val_if_fail (GIMP_IS_FILL_OPTIONS (options), NULL);
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
+
+  context = GIMP_CONTEXT (options);
+
+  return gimp_layer_mode_get_format (gimp_context_get_paint_mode (context),
+                                     GIMP_LAYER_COLOR_SPACE_AUTO,
+                                     GIMP_LAYER_COLOR_SPACE_AUTO,
+                                     gimp_layer_mode_get_paint_composite_mode (
+                                       gimp_context_get_paint_mode (context)),
+                                     gimp_drawable_get_format (drawable));
+}
+
+GeglBuffer *
+gimp_fill_options_create_buffer (GimpFillOptions     *options,
+                                 GimpDrawable        *drawable,
+                                 const GeglRectangle *rect,
+                                 gint                 pattern_offset_x,
+                                 gint                 pattern_offset_y)
+{
+  GeglBuffer *buffer;
+
+  g_return_val_if_fail (GIMP_IS_FILL_OPTIONS (options), NULL);
+  g_return_val_if_fail (gimp_fill_options_get_style (options) !=
+                        GIMP_FILL_STYLE_PATTERN ||
+                        gimp_context_get_pattern (GIMP_CONTEXT (options)) != NULL,
+                        NULL);
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
+  g_return_val_if_fail (rect != NULL, NULL);
+
+  buffer = gegl_buffer_new (rect,
+                            gimp_fill_options_get_format (options, drawable));
+
+  gimp_fill_options_fill_buffer (options, drawable, buffer,
+                                 pattern_offset_x, pattern_offset_y);
+
+  return buffer;
+}
+
+void
+gimp_fill_options_fill_buffer (GimpFillOptions *options,
+                               GimpDrawable    *drawable,
+                               GeglBuffer      *buffer,
+                               gint             pattern_offset_x,
+                               gint             pattern_offset_y)
+{
+  g_return_if_fail (GIMP_IS_FILL_OPTIONS (options));
+  g_return_if_fail (gimp_fill_options_get_style (options) !=
+                    GIMP_FILL_STYLE_PATTERN ||
+                    gimp_context_get_pattern (GIMP_CONTEXT (options)) != NULL);
+  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
+  g_return_if_fail (GEGL_IS_BUFFER (buffer));
+
+  switch (gimp_fill_options_get_style (options))
+    {
+    case GIMP_FILL_STYLE_SOLID:
+      {
+        GimpRGB color;
+
+        gimp_context_get_foreground (GIMP_CONTEXT (options), &color);
+        gimp_palettes_add_color_history (GIMP_CONTEXT (options)->gimp, &color);
+
+        gimp_drawable_fill_buffer (drawable, buffer,
+                                   &color, NULL, 0, 0);
+      }
+      break;
+
+    case GIMP_FILL_STYLE_PATTERN:
+      {
+        GimpPattern *pattern;
+
+        pattern = gimp_context_get_pattern (GIMP_CONTEXT (options));
+
+        gimp_drawable_fill_buffer (drawable, buffer,
+                                   NULL, pattern,
+                                   pattern_offset_x,
+                                   pattern_offset_y);
+      }
+      break;
+    }
+}
diff --git a/app/core/gimpfilloptions.h b/app/core/gimpfilloptions.h
new file mode 100644
index 0000000..434530b
--- /dev/null
+++ b/app/core/gimpfilloptions.h
@@ -0,0 +1,95 @@
+/* The GIMP -- an image manipulation program
+ * Copyright (C) 1995-1999 Spencer Kimball and Peter Mattis
+ *
+ * gimpfilloptions.h
+ * Copyright (C) 2003 Simon Budig
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_FILL_OPTIONS_H__
+#define __GIMP_FILL_OPTIONS_H__
+
+
+#include "gimpcontext.h"
+
+
+#define GIMP_TYPE_FILL_OPTIONS            (gimp_fill_options_get_type ())
+#define GIMP_FILL_OPTIONS(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_FILL_OPTIONS, GimpFillOptions))
+#define GIMP_FILL_OPTIONS_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_FILL_OPTIONS, GimpFillOptionsClass))
+#define GIMP_IS_FILL_OPTIONS(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_FILL_OPTIONS))
+#define GIMP_IS_FILL_OPTIONS_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_FILL_OPTIONS))
+#define GIMP_FILL_OPTIONS_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_FILL_OPTIONS, GimpFillOptionsClass))
+
+
+typedef struct _GimpFillOptionsClass GimpFillOptionsClass;
+
+struct _GimpFillOptions
+{
+  GimpContext  parent_instance;
+};
+
+struct _GimpFillOptionsClass
+{
+  GimpContextClass  parent_class;
+};
+
+
+GType             gimp_fill_options_get_type         (void) G_GNUC_CONST;
+
+GimpFillOptions * gimp_fill_options_new              (Gimp                *gimp,
+                                                      GimpContext         *context,
+                                                      gboolean             use_context_color);
+
+GimpFillStyle     gimp_fill_options_get_style        (GimpFillOptions     *options);
+void              gimp_fill_options_set_style        (GimpFillOptions     *options,
+                                                      GimpFillStyle        style);
+
+gboolean          gimp_fill_options_get_antialias    (GimpFillOptions     *options);
+void              gimp_fill_options_set_antialias    (GimpFillOptions     *options,
+                                                      gboolean             antialias);
+
+gboolean          gimp_fill_options_get_feather      (GimpFillOptions     *options,
+                                                      gdouble             *radius);
+void              gimp_fill_options_set_feather      (GimpFillOptions     *options,
+                                                      gboolean             feather,
+                                                      gdouble              radius);
+
+gboolean          gimp_fill_options_set_by_fill_type (GimpFillOptions     *options,
+                                                      GimpContext         *context,
+                                                      GimpFillType         fill_type,
+                                                      GError             **error);
+gboolean          gimp_fill_options_set_by_fill_mode (GimpFillOptions     *options,
+                                                      GimpContext         *context,
+                                                      GimpBucketFillMode   fill_mode,
+                                                      GError             **error);
+
+const gchar     * gimp_fill_options_get_undo_desc    (GimpFillOptions     *options);
+
+const Babl      * gimp_fill_options_get_format       (GimpFillOptions     *options,
+                                                      GimpDrawable        *drawable);
+
+GeglBuffer      * gimp_fill_options_create_buffer    (GimpFillOptions     *options,
+                                                      GimpDrawable        *drawable,
+                                                      const GeglRectangle *rect,
+                                                      gint                 pattern_offset_x,
+                                                      gint                 pattern_offset_y);
+void              gimp_fill_options_fill_buffer      (GimpFillOptions     *options,
+                                                      GimpDrawable        *drawable,
+                                                      GeglBuffer          *buffer,
+                                                      gint                 pattern_offset_x,
+                                                      gint                 pattern_offset_y);
+
+
+#endif /* __GIMP_FILL_OPTIONS_H__ */
diff --git a/app/core/gimpfilter.c b/app/core/gimpfilter.c
new file mode 100644
index 0000000..f565d49
--- /dev/null
+++ b/app/core/gimpfilter.c
@@ -0,0 +1,315 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpfilter.c
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gimp.h"
+#include "gimp-memsize.h"
+#include "gimpfilter.h"
+#include "gimpmarshal.h"
+
+
+enum
+{
+  ACTIVE_CHANGED,
+  LAST_SIGNAL
+};
+
+enum
+{
+  PROP_0,
+  PROP_ACTIVE,
+  PROP_IS_LAST_NODE
+};
+
+
+typedef struct _GimpFilterPrivate GimpFilterPrivate;
+
+struct _GimpFilterPrivate
+{
+  GeglNode       *node;
+
+  guint           active       : 1;
+  guint           is_last_node : 1;
+
+  GimpApplicator *applicator;
+};
+
+#define GET_PRIVATE(filter) ((GimpFilterPrivate *) gimp_filter_get_instance_private ((GimpFilter *) (filter)))
+
+
+/*  local function prototypes  */
+
+static void       gimp_filter_finalize      (GObject      *object);
+static void       gimp_filter_set_property  (GObject      *object,
+                                             guint         property_id,
+                                             const GValue *value,
+                                             GParamSpec   *pspec);
+static void       gimp_filter_get_property  (GObject      *object,
+                                             guint         property_id,
+                                             GValue       *value,
+                                             GParamSpec   *pspec);
+
+static gint64     gimp_filter_get_memsize   (GimpObject   *object,
+                                             gint64       *gui_size);
+
+static GeglNode * gimp_filter_real_get_node (GimpFilter   *filter);
+
+
+G_DEFINE_TYPE_WITH_PRIVATE (GimpFilter, gimp_filter, GIMP_TYPE_VIEWABLE)
+
+#define parent_class gimp_filter_parent_class
+
+static guint gimp_filter_signals[LAST_SIGNAL] = { 0 };
+
+
+static void
+gimp_filter_class_init (GimpFilterClass *klass)
+{
+  GObjectClass    *object_class      = G_OBJECT_CLASS (klass);
+  GimpObjectClass *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+
+  gimp_filter_signals[ACTIVE_CHANGED] =
+    g_signal_new ("active-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpFilterClass, active_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  object_class->finalize         = gimp_filter_finalize;
+  object_class->set_property     = gimp_filter_set_property;
+  object_class->get_property     = gimp_filter_get_property;
+
+  gimp_object_class->get_memsize = gimp_filter_get_memsize;
+
+  klass->active_changed          = NULL;
+  klass->get_node                = gimp_filter_real_get_node;
+
+  g_object_class_install_property (object_class, PROP_ACTIVE,
+                                   g_param_spec_boolean ("active", NULL, NULL,
+                                                         TRUE,
+                                                         GIMP_PARAM_READWRITE));
+
+  g_object_class_install_property (object_class, PROP_IS_LAST_NODE,
+                                   g_param_spec_boolean ("is-last-node",
+                                                         NULL, NULL,
+                                                         FALSE,
+                                                         GIMP_PARAM_READWRITE));
+}
+
+static void
+gimp_filter_init (GimpFilter *filter)
+{
+  GimpFilterPrivate *private = GET_PRIVATE (filter);
+
+  private->active = TRUE;
+}
+
+static void
+gimp_filter_finalize (GObject *object)
+{
+  GimpFilterPrivate *private = GET_PRIVATE (object);
+
+  g_clear_object (&private->node);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gimp_filter_set_property (GObject      *object,
+                          guint         property_id,
+                          const GValue *value,
+                          GParamSpec   *pspec)
+{
+  GimpFilter *filter = GIMP_FILTER (object);
+
+  switch (property_id)
+    {
+    case PROP_ACTIVE:
+      gimp_filter_set_active (filter, g_value_get_boolean (value));
+      break;
+    case PROP_IS_LAST_NODE:
+      gimp_filter_set_is_last_node (filter, g_value_get_boolean (value));
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_filter_get_property (GObject    *object,
+                          guint       property_id,
+                          GValue     *value,
+                          GParamSpec *pspec)
+{
+  GimpFilterPrivate *private = GET_PRIVATE (object);
+
+  switch (property_id)
+    {
+    case PROP_ACTIVE:
+      g_value_set_boolean (value, private->active);
+      break;
+    case PROP_IS_LAST_NODE:
+      g_value_set_boolean (value, private->is_last_node);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static gint64
+gimp_filter_get_memsize (GimpObject *object,
+                         gint64     *gui_size)
+{
+  GimpFilterPrivate *private = GET_PRIVATE (object);
+  gint64             memsize = 0;
+
+  memsize += gimp_g_object_get_memsize (G_OBJECT (private->node));
+
+  return memsize + GIMP_OBJECT_CLASS (parent_class)->get_memsize (object,
+                                                                  gui_size);
+}
+
+static GeglNode *
+gimp_filter_real_get_node (GimpFilter *filter)
+{
+  GimpFilterPrivate *private = GET_PRIVATE (filter);
+
+  private->node = gegl_node_new ();
+
+  return private->node;
+}
+
+
+/*  public functions  */
+
+GimpFilter *
+gimp_filter_new (const gchar *name)
+{
+  g_return_val_if_fail (name != NULL, NULL);
+
+  return g_object_new (GIMP_TYPE_FILTER,
+                       "name", name,
+                       NULL);
+}
+
+GeglNode *
+gimp_filter_get_node (GimpFilter *filter)
+{
+  GimpFilterPrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_FILTER (filter), NULL);
+
+  private = GET_PRIVATE (filter);
+
+  if (private->node)
+    return private->node;
+
+  return GIMP_FILTER_GET_CLASS (filter)->get_node (filter);
+}
+
+GeglNode *
+gimp_filter_peek_node (GimpFilter *filter)
+{
+  g_return_val_if_fail (GIMP_IS_FILTER (filter), NULL);
+
+  return GET_PRIVATE (filter)->node;
+}
+
+void
+gimp_filter_set_active (GimpFilter *filter,
+                        gboolean    active)
+{
+  g_return_if_fail (GIMP_IS_FILTER (filter));
+
+  active = active ? TRUE : FALSE;
+
+  if (active != gimp_filter_get_active (filter))
+    {
+      GET_PRIVATE (filter)->active = active;
+
+      g_signal_emit (filter, gimp_filter_signals[ACTIVE_CHANGED], 0);
+
+      g_object_notify (G_OBJECT (filter), "active");
+    }
+}
+
+gboolean
+gimp_filter_get_active (GimpFilter *filter)
+{
+  g_return_val_if_fail (GIMP_IS_FILTER (filter), FALSE);
+
+  return GET_PRIVATE (filter)->active;
+}
+
+void
+gimp_filter_set_is_last_node (GimpFilter *filter,
+                              gboolean    is_last_node)
+{
+  g_return_if_fail (GIMP_IS_FILTER (filter));
+
+  is_last_node = is_last_node ? TRUE : FALSE;
+
+  if (is_last_node != gimp_filter_get_is_last_node (filter))
+    {
+      GET_PRIVATE (filter)->is_last_node = is_last_node;
+
+      g_object_notify (G_OBJECT (filter), "is-last-node");
+    }
+}
+
+gboolean
+gimp_filter_get_is_last_node (GimpFilter *filter)
+{
+  g_return_val_if_fail (GIMP_IS_FILTER (filter), FALSE);
+
+  return GET_PRIVATE (filter)->is_last_node;
+}
+
+void
+gimp_filter_set_applicator (GimpFilter     *filter,
+                            GimpApplicator *applicator)
+{
+  GimpFilterPrivate *private;
+
+  g_return_if_fail (GIMP_IS_FILTER (filter));
+
+  private = GET_PRIVATE (filter);
+
+  private->applicator = applicator;
+}
+
+GimpApplicator *
+gimp_filter_get_applicator (GimpFilter *filter)
+{
+  g_return_val_if_fail (GIMP_IS_FILTER (filter), NULL);
+
+  return GET_PRIVATE (filter)->applicator;
+}
diff --git a/app/core/gimpfilter.h b/app/core/gimpfilter.h
new file mode 100644
index 0000000..b1dc922
--- /dev/null
+++ b/app/core/gimpfilter.h
@@ -0,0 +1,73 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpfilter.h
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_FILTER_H__
+#define __GIMP_FILTER_H__
+
+
+#include "gimpviewable.h"
+
+
+#define GIMP_TYPE_FILTER            (gimp_filter_get_type ())
+#define GIMP_FILTER(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_FILTER, GimpFilter))
+#define GIMP_FILTER_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_FILTER, GimpFilterClass))
+#define GIMP_IS_FILTER(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_FILTER))
+#define GIMP_IS_FILTER_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_FILTER))
+#define GIMP_FILTER_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_FILTER, GimpFilterClass))
+
+
+typedef struct _GimpFilterClass GimpFilterClass;
+
+struct _GimpFilter
+{
+  GimpViewable  parent_instance;
+};
+
+struct _GimpFilterClass
+{
+  GimpViewableClass  parent_class;
+
+  /*  signals  */
+  void       (* active_changed) (GimpFilter *filter);
+
+  /*  virtual functions  */
+  GeglNode * (* get_node)       (GimpFilter *filter);
+};
+
+
+GType            gimp_filter_get_type         (void) G_GNUC_CONST;
+GimpFilter     * gimp_filter_new              (const gchar    *name);
+
+GeglNode       * gimp_filter_get_node         (GimpFilter     *filter);
+GeglNode       * gimp_filter_peek_node        (GimpFilter     *filter);
+
+void             gimp_filter_set_active       (GimpFilter     *filter,
+                                               gboolean        active);
+gboolean         gimp_filter_get_active       (GimpFilter     *filter);
+
+void             gimp_filter_set_is_last_node (GimpFilter     *filter,
+                                               gboolean        is_last_node);
+gboolean         gimp_filter_get_is_last_node (GimpFilter     *filter);
+
+void             gimp_filter_set_applicator   (GimpFilter     *filter,
+                                               GimpApplicator *applicator);
+GimpApplicator * gimp_filter_get_applicator   (GimpFilter     *filter);
+
+
+#endif /* __GIMP_FILTER_H__ */
diff --git a/app/core/gimpfilteredcontainer.c b/app/core/gimpfilteredcontainer.c
new file mode 100644
index 0000000..ec56593
--- /dev/null
+++ b/app/core/gimpfilteredcontainer.c
@@ -0,0 +1,373 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1997 Spencer Kimball and Peter Mattis
+ *
+ * gimpfilteredcontainer.c
+ * Copyright (C) 2008 Aurimas Juška <aurisj@svn.gnome.org>
+ *               2011 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <glib-object.h>
+
+#include "core-types.h"
+
+#include "gimpfilteredcontainer.h"
+
+
+enum
+{
+  PROP_0,
+  PROP_SRC_CONTAINER,
+  PROP_FILTER_FUNC,
+  PROP_FILTER_DATA
+};
+
+
+static void     gimp_filtered_container_constructed     (GObject               *object);
+static void     gimp_filtered_container_dispose         (GObject               *object);
+static void     gimp_filtered_container_finalize        (GObject               *object);
+static void     gimp_filtered_container_set_property    (GObject               *object,
+                                                         guint                  property_id,
+                                                         const GValue          *value,
+                                                         GParamSpec            *pspec);
+static void     gimp_filtered_container_get_property    (GObject               *object,
+                                                         guint                  property_id,
+                                                         GValue                *value,
+                                                         GParamSpec            *pspec);
+
+static void     gimp_filtered_container_real_src_add    (GimpFilteredContainer *filtered_container,
+                                                         GimpObject            *object);
+static void     gimp_filtered_container_real_src_remove (GimpFilteredContainer *filtered_container,
+                                                         GimpObject            *object);
+static void     gimp_filtered_container_real_src_freeze (GimpFilteredContainer *filtered_container);
+static void     gimp_filtered_container_real_src_thaw   (GimpFilteredContainer *filtered_container);
+
+static gboolean gimp_filtered_container_object_matches  (GimpFilteredContainer *filtered_container,
+                                                         GimpObject            *object);
+static void     gimp_filtered_container_src_add         (GimpContainer         *src_container,
+                                                         GimpObject            *obj,
+                                                         GimpFilteredContainer *filtered_container);
+static void     gimp_filtered_container_src_remove      (GimpContainer         *src_container,
+                                                         GimpObject            *obj,
+                                                         GimpFilteredContainer *filtered_container);
+static void     gimp_filtered_container_src_freeze      (GimpContainer         *src_container,
+                                                         GimpFilteredContainer *filtered_container);
+static void     gimp_filtered_container_src_thaw        (GimpContainer         *src_container,
+                                                         GimpFilteredContainer *filtered_container);
+
+
+G_DEFINE_TYPE (GimpFilteredContainer, gimp_filtered_container, GIMP_TYPE_LIST)
+
+#define parent_class gimp_filtered_container_parent_class
+
+
+static void
+gimp_filtered_container_class_init (GimpFilteredContainerClass *klass)
+{
+  GObjectClass               *g_object_class = G_OBJECT_CLASS (klass);
+  GimpFilteredContainerClass *filtered_class = GIMP_FILTERED_CONTAINER_CLASS (klass);
+
+  g_object_class->constructed  = gimp_filtered_container_constructed;
+  g_object_class->dispose      = gimp_filtered_container_dispose;
+  g_object_class->finalize     = gimp_filtered_container_finalize;
+  g_object_class->set_property = gimp_filtered_container_set_property;
+  g_object_class->get_property = gimp_filtered_container_get_property;
+
+  filtered_class->src_add      = gimp_filtered_container_real_src_add;
+  filtered_class->src_remove   = gimp_filtered_container_real_src_remove;
+  filtered_class->src_freeze   = gimp_filtered_container_real_src_freeze;
+  filtered_class->src_thaw     = gimp_filtered_container_real_src_thaw;
+
+  g_object_class_install_property (g_object_class, PROP_SRC_CONTAINER,
+                                   g_param_spec_object ("src-container",
+                                                        NULL, NULL,
+                                                        GIMP_TYPE_CONTAINER,
+                                                        GIMP_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT_ONLY));
+
+  g_object_class_install_property (g_object_class, PROP_FILTER_FUNC,
+                                   g_param_spec_pointer ("filter-func",
+                                                         NULL, NULL,
+                                                         GIMP_PARAM_READWRITE |
+                                                         G_PARAM_CONSTRUCT_ONLY));
+
+  g_object_class_install_property (g_object_class, PROP_FILTER_DATA,
+                                   g_param_spec_pointer ("filter-data",
+                                                         NULL, NULL,
+                                                         GIMP_PARAM_READWRITE |
+                                                         G_PARAM_CONSTRUCT_ONLY));
+}
+
+static void
+gimp_filtered_container_init (GimpFilteredContainer *filtered_container)
+{
+}
+
+static void
+gimp_filtered_container_constructed (GObject *object)
+{
+  GimpFilteredContainer *filtered_container = GIMP_FILTERED_CONTAINER (object);
+
+  G_OBJECT_CLASS (parent_class)->constructed (object);
+
+  gimp_assert (GIMP_IS_CONTAINER (filtered_container->src_container));
+
+  if (! gimp_container_frozen (filtered_container->src_container))
+    {
+      /*  a freeze/thaw can't hurt on a newly created container because
+       *  we can't have any views yet. This way we get away without
+       *  having a virtual function for initializing the container.
+       */
+      gimp_filtered_container_src_freeze (filtered_container->src_container,
+                                          filtered_container);
+      gimp_filtered_container_src_thaw (filtered_container->src_container,
+                                        filtered_container);
+    }
+}
+
+static void
+gimp_filtered_container_dispose (GObject *object)
+{
+  GimpFilteredContainer *filtered_container = GIMP_FILTERED_CONTAINER (object);
+
+  if (filtered_container->src_container)
+    {
+      g_signal_handlers_disconnect_by_func (filtered_container->src_container,
+                                            gimp_filtered_container_src_add,
+                                            filtered_container);
+      g_signal_handlers_disconnect_by_func (filtered_container->src_container,
+                                            gimp_filtered_container_src_remove,
+                                            filtered_container);
+      g_signal_handlers_disconnect_by_func (filtered_container->src_container,
+                                            gimp_filtered_container_src_freeze,
+                                            filtered_container);
+      g_signal_handlers_disconnect_by_func (filtered_container->src_container,
+                                            gimp_filtered_container_src_thaw,
+                                            filtered_container);
+    }
+
+  G_OBJECT_CLASS (parent_class)->dispose (object);
+}
+
+static void
+gimp_filtered_container_finalize (GObject *object)
+{
+  GimpFilteredContainer *filtered_container = GIMP_FILTERED_CONTAINER (object);
+
+  g_clear_object (&filtered_container->src_container);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gimp_filtered_container_set_property (GObject      *object,
+                                      guint         property_id,
+                                      const GValue *value,
+                                      GParamSpec   *pspec)
+{
+  GimpFilteredContainer *filtered_container = GIMP_FILTERED_CONTAINER (object);
+
+  switch (property_id)
+    {
+    case PROP_SRC_CONTAINER:
+      filtered_container->src_container = g_value_dup_object (value);
+
+      g_signal_connect (filtered_container->src_container, "add",
+                        G_CALLBACK (gimp_filtered_container_src_add),
+                        filtered_container);
+      g_signal_connect (filtered_container->src_container, "remove",
+                        G_CALLBACK (gimp_filtered_container_src_remove),
+                        filtered_container);
+      g_signal_connect (filtered_container->src_container, "freeze",
+                        G_CALLBACK (gimp_filtered_container_src_freeze),
+                        filtered_container);
+      g_signal_connect (filtered_container->src_container, "thaw",
+                        G_CALLBACK (gimp_filtered_container_src_thaw),
+                        filtered_container);
+      break;
+
+    case PROP_FILTER_FUNC:
+      filtered_container->filter_func = g_value_get_pointer (value);
+      break;
+
+    case PROP_FILTER_DATA:
+      filtered_container->filter_data = g_value_get_pointer (value);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_filtered_container_get_property (GObject    *object,
+                                      guint       property_id,
+                                      GValue     *value,
+                                      GParamSpec *pspec)
+{
+  GimpFilteredContainer *filtered_container = GIMP_FILTERED_CONTAINER (object);
+
+  switch (property_id)
+    {
+    case PROP_SRC_CONTAINER:
+      g_value_set_object (value, filtered_container->src_container);
+      break;
+
+    case PROP_FILTER_FUNC:
+      g_value_set_pointer (value, filtered_container->filter_func);
+      break;
+
+    case PROP_FILTER_DATA:
+      g_value_set_pointer (value, filtered_container->filter_data);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_filtered_container_real_src_add (GimpFilteredContainer *filtered_container,
+                                      GimpObject            *object)
+{
+  if (gimp_filtered_container_object_matches (filtered_container, object))
+    {
+      gimp_container_add (GIMP_CONTAINER (filtered_container), object);
+    }
+}
+
+static void
+gimp_filtered_container_real_src_remove (GimpFilteredContainer *filtered_container,
+                                         GimpObject            *object)
+{
+  if (gimp_filtered_container_object_matches (filtered_container, object))
+    {
+      gimp_container_remove (GIMP_CONTAINER (filtered_container), object);
+    }
+}
+
+static void
+gimp_filtered_container_real_src_freeze (GimpFilteredContainer *filtered_container)
+{
+  gimp_container_clear (GIMP_CONTAINER (filtered_container));
+}
+
+static void
+gimp_filtered_container_real_src_thaw (GimpFilteredContainer *filtered_container)
+{
+  GList *list;
+
+  for (list = GIMP_LIST (filtered_container->src_container)->queue->head;
+       list;
+       list = g_list_next (list))
+    {
+      GimpObject *object = list->data;
+
+      if (gimp_filtered_container_object_matches (filtered_container, object))
+        {
+          gimp_container_add (GIMP_CONTAINER (filtered_container), object);
+        }
+    }
+}
+
+/**
+ * gimp_filtered_container_new:
+ * @src_container: container to be filtered.
+ *
+ * Creates a new #GimpFilteredContainer object which creates filtered
+ * data view of #GimpTagged objects. It filters @src_container for objects
+ * containing all of the filtering tags. Synchronization with @src_container
+ * data is performed automatically.
+ *
+ * Return value: a new #GimpFilteredContainer object.
+ **/
+GimpContainer *
+gimp_filtered_container_new (GimpContainer        *src_container,
+                             GimpObjectFilterFunc  filter_func,
+                             gpointer              filter_data)
+{
+  GType        children_type;
+  GCompareFunc sort_func;
+
+  g_return_val_if_fail (GIMP_IS_LIST (src_container), NULL);
+
+  children_type = gimp_container_get_children_type (src_container);
+  sort_func     = GIMP_LIST (src_container)->sort_func;
+
+  return g_object_new (GIMP_TYPE_FILTERED_CONTAINER,
+                       "sort-func",     sort_func,
+                       "children-type", children_type,
+                       "policy",        GIMP_CONTAINER_POLICY_WEAK,
+                       "unique-names",  FALSE,
+                       "src-container", src_container,
+                       "filter-func",   filter_func,
+                       "filter-data",   filter_data,
+                       NULL);
+}
+
+static gboolean
+gimp_filtered_container_object_matches (GimpFilteredContainer *filtered_container,
+                                        GimpObject            *object)
+{
+  return (! filtered_container->filter_func ||
+          filtered_container->filter_func (object,
+                                           filtered_container->filter_data));
+}
+
+static void
+gimp_filtered_container_src_add (GimpContainer         *src_container,
+                                 GimpObject            *object,
+                                 GimpFilteredContainer *filtered_container)
+{
+  if (! gimp_container_frozen (filtered_container->src_container))
+    {
+      GIMP_FILTERED_CONTAINER_GET_CLASS (filtered_container)->src_add (filtered_container,
+                                                                       object);
+    }
+}
+
+static void
+gimp_filtered_container_src_remove (GimpContainer         *src_container,
+                                    GimpObject            *object,
+                                    GimpFilteredContainer *filtered_container)
+{
+  if (! gimp_container_frozen (filtered_container->src_container))
+    {
+      GIMP_FILTERED_CONTAINER_GET_CLASS (filtered_container)->src_remove (filtered_container,
+                                                                          object);
+    }
+}
+
+static void
+gimp_filtered_container_src_freeze (GimpContainer         *src_container,
+                                    GimpFilteredContainer *filtered_container)
+{
+  gimp_container_freeze (GIMP_CONTAINER (filtered_container));
+
+  GIMP_FILTERED_CONTAINER_GET_CLASS (filtered_container)->src_freeze (filtered_container);
+}
+
+static void
+gimp_filtered_container_src_thaw (GimpContainer         *src_container,
+                                  GimpFilteredContainer *filtered_container)
+{
+  GIMP_FILTERED_CONTAINER_GET_CLASS (filtered_container)->src_thaw (filtered_container);
+
+  gimp_container_thaw (GIMP_CONTAINER (filtered_container));
+}
diff --git a/app/core/gimpfilteredcontainer.h b/app/core/gimpfilteredcontainer.h
new file mode 100644
index 0000000..28803c8
--- /dev/null
+++ b/app/core/gimpfilteredcontainer.h
@@ -0,0 +1,68 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1997 Spencer Kimball and Peter Mattis
+ *
+ * gimpfilteredcontainer.h
+ * Copyright (C) 2008 Aurimas Juška <aurisj@svn.gnome.org>
+ *               2011 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_FILTERED_CONTAINER_H__
+#define __GIMP_FILTERED_CONTAINER_H__
+
+
+#include "gimplist.h"
+
+
+#define GIMP_TYPE_FILTERED_CONTAINER            (gimp_filtered_container_get_type ())
+#define GIMP_FILTERED_CONTAINER(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_FILTERED_CONTAINER, GimpFilteredContainer))
+#define GIMP_FILTERED_CONTAINER_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_FILTERED_CONTAINER, GimpFilteredContainerClass))
+#define GIMP_IS_FILTERED_CONTAINER(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_FILTERED_CONTAINER))
+#define GIMP_IS_FILTERED_CONTAINER_CLASS(class) (G_TYPE_CHECK_CLASS_TYPE ((class), GIMP_TYPE_FILTERED_CONTAINER))
+#define GIMP_FILTERED_CONTAINER_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_FILTERED_CONTAINER, GimpFilteredContainerClass))
+
+
+typedef struct _GimpFilteredContainerClass GimpFilteredContainerClass;
+
+struct _GimpFilteredContainer
+{
+  GimpList              parent_instance;
+
+  GimpContainer        *src_container;
+  GimpObjectFilterFunc  filter_func;
+  gpointer              filter_data;
+};
+
+struct _GimpFilteredContainerClass
+{
+  GimpContainerClass  parent_class;
+
+  void (* src_add)    (GimpFilteredContainer *filtered_container,
+                       GimpObject            *object);
+  void (* src_remove) (GimpFilteredContainer *filtered_container,
+                       GimpObject            *object);
+  void (* src_freeze) (GimpFilteredContainer *filtered_container);
+  void (* src_thaw)   (GimpFilteredContainer *filtered_container);
+};
+
+
+GType           gimp_filtered_container_get_type (void) G_GNUC_CONST;
+
+GimpContainer * gimp_filtered_container_new      (GimpContainer        *src_container,
+                                                  GimpObjectFilterFunc  filter_func,
+                                                  gpointer              filter_data);
+
+
+#endif  /* __GIMP_FILTERED_CONTAINER_H__ */
diff --git a/app/core/gimpfilterstack.c b/app/core/gimpfilterstack.c
new file mode 100644
index 0000000..09d9cfd
--- /dev/null
+++ b/app/core/gimpfilterstack.c
@@ -0,0 +1,350 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1997 Spencer Kimball and Peter Mattis
+ *
+ * gimpfilterstack.c
+ * Copyright (C) 2008-2013 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gimpfilter.h"
+#include "gimpfilterstack.h"
+
+
+/*  local function prototypes  */
+
+static void   gimp_filter_stack_constructed      (GObject         *object);
+static void   gimp_filter_stack_finalize         (GObject         *object);
+
+static void   gimp_filter_stack_add              (GimpContainer   *container,
+                                                  GimpObject      *object);
+static void   gimp_filter_stack_remove           (GimpContainer   *container,
+                                                  GimpObject      *object);
+static void   gimp_filter_stack_reorder          (GimpContainer   *container,
+                                                  GimpObject      *object,
+                                                  gint             new_index);
+
+static void   gimp_filter_stack_add_node         (GimpFilterStack *stack,
+                                                  GimpFilter      *filter);
+static void   gimp_filter_stack_remove_node      (GimpFilterStack *stack,
+                                                  GimpFilter      *filter);
+static void   gimp_filter_stack_update_last_node (GimpFilterStack *stack);
+
+static void   gimp_filter_stack_filter_active    (GimpFilter      *filter,
+                                                  GimpFilterStack *stack);
+
+
+G_DEFINE_TYPE (GimpFilterStack, gimp_filter_stack, GIMP_TYPE_LIST);
+
+#define parent_class gimp_filter_stack_parent_class
+
+
+static void
+gimp_filter_stack_class_init (GimpFilterStackClass *klass)
+{
+  GObjectClass       *object_class    = G_OBJECT_CLASS (klass);
+  GimpContainerClass *container_class = GIMP_CONTAINER_CLASS (klass);
+
+  object_class->constructed = gimp_filter_stack_constructed;
+  object_class->finalize    = gimp_filter_stack_finalize;
+
+  container_class->add      = gimp_filter_stack_add;
+  container_class->remove   = gimp_filter_stack_remove;
+  container_class->reorder  = gimp_filter_stack_reorder;
+}
+
+static void
+gimp_filter_stack_init (GimpFilterStack *stack)
+{
+}
+
+static void
+gimp_filter_stack_constructed (GObject *object)
+{
+  GimpContainer *container = GIMP_CONTAINER (object);
+
+  G_OBJECT_CLASS (parent_class)->constructed (object);
+
+  gimp_assert (g_type_is_a (gimp_container_get_children_type (container),
+                            GIMP_TYPE_FILTER));
+
+  gimp_container_add_handler (container, "active-changed",
+                              G_CALLBACK (gimp_filter_stack_filter_active),
+                              container);
+}
+
+static void
+gimp_filter_stack_finalize (GObject *object)
+{
+  GimpFilterStack *stack = GIMP_FILTER_STACK (object);
+
+  g_clear_object (&stack->graph);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gimp_filter_stack_add (GimpContainer *container,
+                       GimpObject    *object)
+{
+  GimpFilterStack *stack  = GIMP_FILTER_STACK (container);
+  GimpFilter      *filter = GIMP_FILTER (object);
+
+  GIMP_CONTAINER_CLASS (parent_class)->add (container, object);
+
+  if (gimp_filter_get_active (filter))
+    {
+      if (stack->graph)
+        {
+          gegl_node_add_child (stack->graph, gimp_filter_get_node (filter));
+          gimp_filter_stack_add_node (stack, filter);
+        }
+
+      gimp_filter_stack_update_last_node (stack);
+    }
+}
+
+static void
+gimp_filter_stack_remove (GimpContainer *container,
+                          GimpObject    *object)
+{
+  GimpFilterStack *stack  = GIMP_FILTER_STACK (container);
+  GimpFilter      *filter = GIMP_FILTER (object);
+
+  if (stack->graph && gimp_filter_get_active (filter))
+    {
+      gimp_filter_stack_remove_node (stack, filter);
+      gegl_node_remove_child (stack->graph, gimp_filter_get_node (filter));
+    }
+
+  GIMP_CONTAINER_CLASS (parent_class)->remove (container, object);
+
+  if (gimp_filter_get_active (filter))
+    {
+      gimp_filter_set_is_last_node (filter, FALSE);
+      gimp_filter_stack_update_last_node (stack);
+    }
+}
+
+static void
+gimp_filter_stack_reorder (GimpContainer *container,
+                           GimpObject    *object,
+                           gint           new_index)
+{
+  GimpFilterStack *stack  = GIMP_FILTER_STACK (container);
+  GimpFilter      *filter = GIMP_FILTER (object);
+
+  if (stack->graph && gimp_filter_get_active (filter))
+    gimp_filter_stack_remove_node (stack, filter);
+
+  GIMP_CONTAINER_CLASS (parent_class)->reorder (container, object, new_index);
+
+  if (gimp_filter_get_active (filter))
+    {
+      gimp_filter_stack_update_last_node (stack);
+
+      if (stack->graph)
+        gimp_filter_stack_add_node (stack, filter);
+    }
+}
+
+
+/*  public functions  */
+
+GimpContainer *
+gimp_filter_stack_new (GType filter_type)
+{
+  g_return_val_if_fail (g_type_is_a (filter_type, GIMP_TYPE_FILTER), NULL);
+
+  return g_object_new (GIMP_TYPE_FILTER_STACK,
+                       "name",          g_type_name (filter_type),
+                       "children-type", filter_type,
+                       "policy",        GIMP_CONTAINER_POLICY_STRONG,
+                       NULL);
+}
+
+GeglNode *
+gimp_filter_stack_get_graph (GimpFilterStack *stack)
+{
+  GList    *list;
+  GeglNode *previous;
+  GeglNode *output;
+
+  g_return_val_if_fail (GIMP_IS_FILTER_STACK (stack), NULL);
+
+  if (stack->graph)
+    return stack->graph;
+
+  stack->graph = gegl_node_new ();
+
+  previous = gegl_node_get_input_proxy (stack->graph, "input");
+
+  for (list = GIMP_LIST (stack)->queue->tail;
+       list;
+       list = g_list_previous (list))
+    {
+      GimpFilter *filter = list->data;
+      GeglNode   *node;
+
+      if (! gimp_filter_get_active (filter))
+        continue;
+
+      node = gimp_filter_get_node (filter);
+
+      gegl_node_add_child (stack->graph, node);
+
+      gegl_node_connect_to (previous, "output",
+                            node,     "input");
+
+      previous = node;
+    }
+
+  output = gegl_node_get_output_proxy (stack->graph, "output");
+
+  gegl_node_connect_to (previous, "output",
+                        output,   "input");
+
+  return stack->graph;
+}
+
+
+/*  private functions  */
+
+static void
+gimp_filter_stack_add_node (GimpFilterStack *stack,
+                            GimpFilter      *filter)
+{
+  GeglNode *node;
+  GeglNode *node_above = NULL;
+  GeglNode *node_below = NULL;
+  GList    *iter;
+
+  node = gimp_filter_get_node (filter);
+
+
+  iter = g_list_find (GIMP_LIST (stack)->queue->head, filter);
+
+  while ((iter = g_list_previous (iter)))
+    {
+      GimpFilter *filter_above = iter->data;
+
+      if (gimp_filter_get_active (filter_above))
+        {
+          node_above = gimp_filter_get_node (filter_above);
+
+          break;
+        }
+    }
+
+  if (! node_above)
+    node_above = gegl_node_get_output_proxy (stack->graph, "output");
+
+  node_below = gegl_node_get_producer (node_above, "input", NULL);
+
+  gegl_node_connect_to (node_below, "output",
+                        node,       "input");
+  gegl_node_connect_to (node,       "output",
+                        node_above, "input");
+}
+
+static void
+gimp_filter_stack_remove_node (GimpFilterStack *stack,
+                               GimpFilter      *filter)
+{
+  GeglNode *node;
+  GeglNode *node_above = NULL;
+  GeglNode *node_below = NULL;
+  GList    *iter;
+
+  node = gimp_filter_get_node (filter);
+
+  iter = g_list_find (GIMP_LIST (stack)->queue->head, filter);
+
+  while ((iter = g_list_previous (iter)))
+    {
+      GimpFilter *filter_above = iter->data;
+
+      if (gimp_filter_get_active (filter_above))
+        {
+          node_above = gimp_filter_get_node (filter_above);
+
+          break;
+        }
+    }
+
+  if (! node_above)
+    node_above = gegl_node_get_output_proxy (stack->graph, "output");
+
+  node_below = gegl_node_get_producer (node, "input", NULL);
+
+  gegl_node_disconnect (node, "input");
+
+  gegl_node_connect_to (node_below, "output",
+                        node_above, "input");
+}
+
+static void
+gimp_filter_stack_update_last_node (GimpFilterStack *stack)
+{
+  GList    *list;
+  gboolean  found_last = FALSE;
+
+  for (list = GIMP_LIST (stack)->queue->tail;
+       list;
+       list = g_list_previous (list))
+    {
+      GimpFilter *filter = list->data;
+
+      if (! found_last && gimp_filter_get_active (filter))
+        {
+          gimp_filter_set_is_last_node (filter, TRUE);
+          found_last = TRUE;
+        }
+      else
+        {
+          gimp_filter_set_is_last_node (filter, FALSE);
+        }
+    }
+}
+
+static void
+gimp_filter_stack_filter_active (GimpFilter      *filter,
+                                 GimpFilterStack *stack)
+{
+  if (stack->graph)
+    {
+      if (gimp_filter_get_active (filter))
+        {
+          gegl_node_add_child (stack->graph, gimp_filter_get_node (filter));
+          gimp_filter_stack_add_node (stack, filter);
+        }
+      else
+        {
+          gimp_filter_stack_remove_node (stack, filter);
+          gegl_node_remove_child (stack->graph, gimp_filter_get_node (filter));
+        }
+    }
+
+  gimp_filter_stack_update_last_node (stack);
+
+  if (! gimp_filter_get_active (filter))
+    gimp_filter_set_is_last_node (filter, FALSE);
+}
diff --git a/app/core/gimpfilterstack.h b/app/core/gimpfilterstack.h
new file mode 100644
index 0000000..3567f06
--- /dev/null
+++ b/app/core/gimpfilterstack.h
@@ -0,0 +1,55 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1997 Spencer Kimball and Peter Mattis
+ *
+ * gimpfilterstack.h
+ * Copyright (C) 2008-2013 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_FILTER_STACK_H__
+#define __GIMP_FILTER_STACK_H__
+
+#include "gimplist.h"
+
+
+#define GIMP_TYPE_FILTER_STACK            (gimp_filter_stack_get_type ())
+#define GIMP_FILTER_STACK(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_FILTER_STACK, GimpFilterStack))
+#define GIMP_FILTER_STACK_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_FILTER_STACK, GimpFilterStackClass))
+#define GIMP_IS_FILTER_STACK(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_FILTER_STACK))
+#define GIMP_IS_FILTER_STACK_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_FILTER_STACK))
+
+
+typedef struct _GimpFilterStackClass GimpFilterStackClass;
+
+struct _GimpFilterStack
+{
+  GimpList  parent_instance;
+
+  GeglNode *graph;
+};
+
+struct _GimpFilterStackClass
+{
+  GimpListClass  parent_class;
+};
+
+
+GType           gimp_filter_stack_get_type  (void) G_GNUC_CONST;
+GimpContainer * gimp_filter_stack_new       (GType            filter_type);
+
+GeglNode *      gimp_filter_stack_get_graph (GimpFilterStack *stack);
+
+
+#endif  /*  __GIMP_FILTER_STACK_H__  */
diff --git a/app/core/gimpfloatingselectionundo.c b/app/core/gimpfloatingselectionundo.c
new file mode 100644
index 0000000..6ca28ab
--- /dev/null
+++ b/app/core/gimpfloatingselectionundo.c
@@ -0,0 +1,135 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gimpdrawable-floating-selection.h"
+#include "gimpfloatingselectionundo.h"
+#include "gimpimage.h"
+#include "gimplayer.h"
+#include "gimplayer-floating-selection.h"
+
+
+static void   gimp_floating_selection_undo_constructed (GObject             *object);
+
+static void   gimp_floating_selection_undo_pop         (GimpUndo            *undo,
+                                                        GimpUndoMode         undo_mode,
+                                                        GimpUndoAccumulator *accum);
+
+
+G_DEFINE_TYPE (GimpFloatingSelectionUndo, gimp_floating_selection_undo,
+               GIMP_TYPE_ITEM_UNDO)
+
+#define parent_class gimp_floating_selection_undo_parent_class
+
+
+static void
+gimp_floating_selection_undo_class_init (GimpFloatingSelectionUndoClass *klass)
+{
+  GObjectClass  *object_class = G_OBJECT_CLASS (klass);
+  GimpUndoClass *undo_class   = GIMP_UNDO_CLASS (klass);
+
+  object_class->constructed = gimp_floating_selection_undo_constructed;
+
+  undo_class->pop           = gimp_floating_selection_undo_pop;
+}
+
+static void
+gimp_floating_selection_undo_init (GimpFloatingSelectionUndo *undo)
+{
+}
+
+static void
+gimp_floating_selection_undo_constructed (GObject *object)
+{
+  GimpFloatingSelectionUndo *floating_sel_undo;
+  GimpLayer                 *layer;
+
+  floating_sel_undo = GIMP_FLOATING_SELECTION_UNDO (object);
+
+  G_OBJECT_CLASS (parent_class)->constructed (object);
+
+  gimp_assert (GIMP_IS_LAYER (GIMP_ITEM_UNDO (object)->item));
+
+  layer = GIMP_LAYER (GIMP_ITEM_UNDO (object)->item);
+
+  switch (GIMP_UNDO (object)->undo_type)
+    {
+    case GIMP_UNDO_FS_TO_LAYER:
+      floating_sel_undo->drawable = gimp_layer_get_floating_sel_drawable (layer);
+      break;
+
+    default:
+      g_return_if_reached ();
+    }
+}
+
+static void
+gimp_floating_selection_undo_pop (GimpUndo            *undo,
+                                  GimpUndoMode         undo_mode,
+                                  GimpUndoAccumulator *accum)
+{
+  GimpFloatingSelectionUndo *floating_sel_undo;
+  GimpLayer                 *floating_layer;
+
+  floating_sel_undo = GIMP_FLOATING_SELECTION_UNDO (undo);
+  floating_layer    = GIMP_LAYER (GIMP_ITEM_UNDO (undo)->item);
+
+  GIMP_UNDO_CLASS (parent_class)->pop (undo, undo_mode, accum);
+
+  switch (undo->undo_type)
+    {
+    case GIMP_UNDO_FS_TO_LAYER:
+      if (undo_mode == GIMP_UNDO_MODE_UNDO)
+        {
+          /*  Update the preview for the floating selection  */
+          gimp_viewable_invalidate_preview (GIMP_VIEWABLE (floating_layer));
+
+          gimp_layer_set_floating_sel_drawable (floating_layer,
+                                                floating_sel_undo->drawable);
+          gimp_image_set_active_layer (undo->image, floating_layer);
+
+          gimp_drawable_attach_floating_sel (gimp_layer_get_floating_sel_drawable (floating_layer),
+                                             floating_layer);
+        }
+      else
+        {
+          gimp_drawable_detach_floating_sel (gimp_layer_get_floating_sel_drawable (floating_layer));
+          gimp_layer_set_floating_sel_drawable (floating_layer, NULL);
+        }
+
+      /* When the floating selection is converted to/from a normal
+       * layer it does something resembling a name change, so emit the
+       * "name-changed" signal
+       */
+      gimp_object_name_changed (GIMP_OBJECT (floating_layer));
+
+      gimp_drawable_update (GIMP_DRAWABLE (floating_layer),
+                            0, 0,
+                            gimp_item_get_width  (GIMP_ITEM (floating_layer)),
+                            gimp_item_get_height (GIMP_ITEM (floating_layer)));
+      break;
+
+    default:
+      g_return_if_reached ();
+    }
+}
diff --git a/app/core/gimpfloatingselectionundo.h b/app/core/gimpfloatingselectionundo.h
new file mode 100644
index 0000000..4d9a626
--- /dev/null
+++ b/app/core/gimpfloatingselectionundo.h
@@ -0,0 +1,52 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_FLOATING_SELECTION_UNDO_H__
+#define __GIMP_FLOATING_SELECTION_UNDO_H__
+
+
+#include "gimpitemundo.h"
+
+
+#define GIMP_TYPE_FLOATING_SELECTION_UNDO            (gimp_floating_selection_undo_get_type ())
+#define GIMP_FLOATING_SELECTION_UNDO(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_FLOATING_SELECTION_UNDO, GimpFloatingSelectionUndo))
+#define GIMP_FLOATING_SELECTION_UNDO_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_FLOATING_SELECTION_UNDO, GimpFloatingSelectionUndoClass))
+#define GIMP_IS_FLOATING_SELECTION_UNDO(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_FLOATING_SELECTION_UNDO))
+#define GIMP_IS_FLOATING_SELECTION_UNDO_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_FLOATING_SELECTION_UNDO))
+#define GIMP_FLOATING_SELECTION_UNDO_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_FLOATING_SELECTION_UNDO, GimpFloatingSelectionUndoClass))
+
+
+typedef struct _GimpFloatingSelectionUndo      GimpFloatingSelectionUndo;
+typedef struct _GimpFloatingSelectionUndoClass GimpFloatingSelectionUndoClass;
+
+struct _GimpFloatingSelectionUndo
+{
+  GimpItemUndo  parent_instance;
+
+  GimpDrawable *drawable;
+};
+
+struct _GimpFloatingSelectionUndoClass
+{
+  GimpItemUndoClass  parent_class;
+};
+
+
+GType   gimp_floating_selection_undo_get_type (void) G_GNUC_CONST;
+
+
+#endif /* __GIMP_FLOATING_SELECTION_UNDO_H__ */
diff --git a/app/core/gimpgradient-load.c b/app/core/gimpgradient-load.c
new file mode 100644
index 0000000..1abe494
--- /dev/null
+++ b/app/core/gimpgradient-load.c
@@ -0,0 +1,575 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+
+#include <cairo.h>
+#include <gegl.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpcolor/gimpcolor.h"
+
+#include "core-types.h"
+
+#include "config/gimpxmlparser.h"
+
+#include "gimp-utils.h"
+#include "gimpgradient.h"
+#include "gimpgradient-load.h"
+
+#include "gimp-intl.h"
+
+
+GList *
+gimp_gradient_load (GimpContext   *context,
+                    GFile         *file,
+                    GInputStream  *input,
+                    GError       **error)
+{
+  GimpGradient        *gradient = NULL;
+  GimpGradientSegment *prev;
+  gint                 num_segments;
+  gint                 i;
+  GDataInputStream    *data_input;
+  gchar               *line;
+  gsize                line_len;
+  gint                 linenum;
+
+  g_return_val_if_fail (G_IS_FILE (file), NULL);
+  g_return_val_if_fail (G_IS_INPUT_STREAM (input), NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, NULL);
+
+  data_input = g_data_input_stream_new (input);
+
+  linenum = 1;
+  line_len = 1024;
+  line = gimp_data_input_stream_read_line_always (data_input, &line_len,
+                                                  NULL, error);
+  if (! line)
+    goto failed;
+
+  if (! g_str_has_prefix (line, "GIMP Gradient"))
+    {
+      g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                   _("Not a GIMP gradient file."));
+      g_free (line);
+      goto failed;
+    }
+
+  g_free (line);
+
+  gradient = g_object_new (GIMP_TYPE_GRADIENT,
+                           "mime-type", "application/x-gimp-gradient",
+                           NULL);
+
+  linenum++;
+  line_len = 1024;
+  line = gimp_data_input_stream_read_line_always (data_input, &line_len,
+                                                  NULL, error);
+  if (! line)
+    goto failed;
+
+  if (g_str_has_prefix (line, "Name: "))
+    {
+      gchar *utf8;
+
+      utf8 = gimp_any_to_utf8 (g_strstrip (line + strlen ("Name: ")), -1,
+                               _("Invalid UTF-8 string in gradient file '%s'."),
+                               gimp_file_get_utf8_name (file));
+      gimp_object_take_name (GIMP_OBJECT (gradient), utf8);
+
+      g_free (line);
+
+      linenum++;
+      line_len = 1024;
+      line = gimp_data_input_stream_read_line_always (data_input, &line_len,
+                                                      NULL, error);
+      if (! line)
+        goto failed;
+    }
+  else /* old gradient format */
+    {
+      gimp_object_take_name (GIMP_OBJECT (gradient),
+                             g_path_get_basename (gimp_file_get_utf8_name (file)));
+    }
+
+  num_segments = atoi (line);
+
+  g_free (line);
+
+  if (num_segments < 1)
+    {
+      g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                   _("File is corrupt."));
+      goto failed;
+    }
+
+  prev = NULL;
+
+  for (i = 0; i < num_segments; i++)
+    {
+      GimpGradientSegment *seg;
+      gchar               *end;
+      gint                 color;
+      gint                 type;
+      gint                 left_color_type;
+      gint                 right_color_type;
+
+      seg = gimp_gradient_segment_new ();
+
+      seg->prev = prev;
+
+      if (prev)
+        prev->next = seg;
+      else
+        gradient->segments = seg;
+
+      linenum++;
+      line_len = 1024;
+      line = gimp_data_input_stream_read_line_always (data_input, &line_len,
+                                                      NULL, error);
+      if (! line)
+        goto failed;
+
+      if (! gimp_ascii_strtod (line, &end, &seg->left)          ||
+          ! gimp_ascii_strtod (end,  &end, &seg->middle)        ||
+          ! gimp_ascii_strtod (end,  &end, &seg->right)         ||
+
+          ! gimp_ascii_strtod (end,  &end, &seg->left_color.r)  ||
+          ! gimp_ascii_strtod (end,  &end, &seg->left_color.g)  ||
+          ! gimp_ascii_strtod (end,  &end, &seg->left_color.b)  ||
+          ! gimp_ascii_strtod (end,  &end, &seg->left_color.a)  ||
+
+          ! gimp_ascii_strtod (end,  &end, &seg->right_color.r) ||
+          ! gimp_ascii_strtod (end,  &end, &seg->right_color.g) ||
+          ! gimp_ascii_strtod (end,  &end, &seg->right_color.b) ||
+          ! gimp_ascii_strtod (end,  &end, &seg->right_color.a))
+        {
+          g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                       _("Corrupt segment %d."), i);
+          g_free (line);
+          goto failed;
+        }
+
+      switch (sscanf (end, "%d %d %d %d",
+                      &type, &color,
+                      &left_color_type, &right_color_type))
+        {
+        case 4:
+          seg->left_color_type  = (GimpGradientColor) left_color_type;
+          if (seg->left_color_type < GIMP_GRADIENT_COLOR_FIXED ||
+              seg->left_color_type > GIMP_GRADIENT_COLOR_BACKGROUND_TRANSPARENT)
+            {
+              g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                           _("Corrupt segment %d."), i);
+              g_free (line);
+              goto failed;
+            }
+
+          seg->right_color_type = (GimpGradientColor) right_color_type;
+          if (seg->right_color_type < GIMP_GRADIENT_COLOR_FIXED ||
+              seg->right_color_type > GIMP_GRADIENT_COLOR_BACKGROUND_TRANSPARENT)
+            {
+              g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                           _("Corrupt segment %d."), i);
+              g_free (line);
+              goto failed;
+            }
+          /* fall thru */
+
+        case 2:
+          seg->type  = (GimpGradientSegmentType) type;
+          if (seg->type < GIMP_GRADIENT_SEGMENT_LINEAR ||
+              seg->type > GIMP_GRADIENT_SEGMENT_STEP)
+            {
+              g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                           _("Corrupt segment %d."), i);
+              g_free (line);
+              goto failed;
+            }
+
+          seg->color = (GimpGradientSegmentColor) color;
+          if (seg->color < GIMP_GRADIENT_SEGMENT_RGB ||
+              seg->color > GIMP_GRADIENT_SEGMENT_HSV_CW)
+            {
+              g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                           _("Corrupt segment %d."), i);
+              g_free (line);
+              goto failed;
+            }
+          break;
+
+        default:
+          g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                       _("Corrupt segment %d."), i);
+          g_free (line);
+          goto failed;
+        }
+
+      g_free (line);
+
+      if (seg->left   > seg->middle              ||
+          seg->middle > seg->right               ||
+          (  prev && (prev->right != seg->left)) ||
+          (! prev && (0.0         != seg->left)))
+        {
+          g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                       _("Segments do not span the range 0-1."));
+          goto failed;
+        }
+
+      prev = seg;
+    }
+
+  if (prev->right != 1.0)
+    {
+      g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                   _("Segments do not span the range 0-1."));
+      goto failed;
+    }
+
+  g_object_unref (data_input);
+
+  return g_list_prepend (NULL, gradient);
+
+ failed:
+
+  g_object_unref (data_input);
+
+  if (gradient)
+    g_object_unref (gradient);
+
+  g_prefix_error (error, _("In line %d of gradient file: "), linenum);
+
+  return NULL;
+}
+
+
+/*  SVG gradient parser  */
+
+typedef struct
+{
+  GimpGradient *gradient;  /*  current gradient    */
+  GList        *gradients; /*  finished gradients  */
+  GList        *stops;
+} SvgParser;
+
+typedef struct
+{
+  gdouble       offset;
+  GimpRGB       color;
+} SvgStop;
+
+
+static void     svg_parser_start_element  (GMarkupParseContext  *context,
+                                           const gchar          *element_name,
+                                           const gchar         **attribute_names,
+                                           const gchar         **attribute_values,
+                                           gpointer              user_data,
+                                           GError              **error);
+static void      svg_parser_end_element   (GMarkupParseContext  *context,
+                                           const gchar          *element_name,
+                                           gpointer              user_data,
+                                           GError              **error);
+
+static GimpGradientSegment *
+                 svg_parser_gradient_segments   (GList          *stops);
+
+static SvgStop * svg_parse_gradient_stop        (const gchar   **names,
+                                                 const gchar   **values);
+
+
+static const GMarkupParser markup_parser =
+{
+  svg_parser_start_element,
+  svg_parser_end_element,
+  NULL,  /*  characters   */
+  NULL,  /*  passthrough  */
+  NULL   /*  error        */
+};
+
+
+GList *
+gimp_gradient_load_svg (GimpContext   *context,
+                        GFile         *file,
+                        GInputStream  *input,
+                        GError       **error)
+{
+  GimpXmlParser *xml_parser;
+  SvgParser      parser = { NULL, };
+  gboolean       success;
+
+  g_return_val_if_fail (G_IS_FILE (file), NULL);
+  g_return_val_if_fail (G_IS_INPUT_STREAM (input), NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, NULL);
+
+  /* FIXME input */
+  g_input_stream_close (input, NULL, NULL);
+
+  xml_parser = gimp_xml_parser_new (&markup_parser, &parser);
+
+  success = gimp_xml_parser_parse_gfile (xml_parser, file, error);
+
+  gimp_xml_parser_free (xml_parser);
+
+  if (success && ! parser.gradients)
+    {
+      g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                   _("No linear gradients found."));
+    }
+
+  if (parser.gradient)
+    g_object_unref (parser.gradient);
+
+  if (parser.stops)
+    {
+      GList *list;
+
+      for (list = parser.stops; list; list = list->next)
+        g_slice_free (SvgStop, list->data);
+
+      g_list_free (parser.stops);
+    }
+
+  return g_list_reverse (parser.gradients);
+}
+
+static void
+svg_parser_start_element (GMarkupParseContext  *context,
+                          const gchar          *element_name,
+                          const gchar         **attribute_names,
+                          const gchar         **attribute_values,
+                          gpointer              user_data,
+                          GError              **error)
+{
+  SvgParser *parser = user_data;
+
+  if (! parser->gradient && strcmp (element_name, "linearGradient") == 0)
+    {
+      const gchar *name = NULL;
+
+      while (*attribute_names && *attribute_values)
+        {
+          if (strcmp (*attribute_names, "id") == 0 && *attribute_values)
+            name = *attribute_values;
+
+          attribute_names++;
+          attribute_values++;
+        }
+
+      parser->gradient = g_object_new (GIMP_TYPE_GRADIENT,
+                                       "name",      name,
+                                       "mime-type", "image/svg+xml",
+                                       NULL);
+    }
+  else if (parser->gradient && strcmp (element_name, "stop") == 0)
+    {
+      SvgStop *stop = svg_parse_gradient_stop (attribute_names,
+                                               attribute_values);
+
+      /*  The spec clearly states that each gradient stop's offset
+       *  value is required to be equal to or greater than the
+       *  previous gradient stop's offset value.
+       */
+      if (parser->stops)
+        stop->offset = MAX (stop->offset,
+                            ((SvgStop *) parser->stops->data)->offset);
+
+      parser->stops = g_list_prepend (parser->stops, stop);
+    }
+}
+
+static void
+svg_parser_end_element (GMarkupParseContext  *context,
+                        const gchar          *element_name,
+                        gpointer              user_data,
+                        GError              **error)
+{
+  SvgParser *parser = user_data;
+
+  if (parser->gradient &&
+      strcmp (element_name, "linearGradient") == 0)
+    {
+      GList *list;
+
+      parser->gradient->segments = svg_parser_gradient_segments (parser->stops);
+
+      for (list = parser->stops; list; list = list->next)
+        g_slice_free (SvgStop, list->data);
+
+      g_list_free (parser->stops);
+      parser->stops = NULL;
+
+      if (parser->gradient->segments)
+        parser->gradients = g_list_prepend (parser->gradients,
+                                            parser->gradient);
+      else
+        g_object_unref (parser->gradient);
+
+      parser->gradient = NULL;
+    }
+}
+
+static GimpGradientSegment *
+svg_parser_gradient_segments (GList *stops)
+{
+  GimpGradientSegment *segment;
+  SvgStop             *stop;
+  GList               *list;
+
+  if (! stops)
+    return NULL;
+
+  stop = stops->data;
+
+  segment = gimp_gradient_segment_new ();
+
+  segment->left_color  = stop->color;
+  segment->right_color = stop->color;
+
+  /*  the list of offsets is sorted from largest to smallest  */
+  for (list = g_list_next (stops); list; list = g_list_next (list))
+    {
+      GimpGradientSegment *next = segment;
+
+      segment->left   = stop->offset;
+      segment->middle = (segment->left + segment->right) / 2.0;
+
+      segment = gimp_gradient_segment_new ();
+
+      segment->next = next;
+      next->prev    = segment;
+
+      segment->right       = stop->offset;
+      segment->right_color = stop->color;
+
+      stop = list->data;
+
+      segment->left_color  = stop->color;
+    }
+
+  segment->middle = (segment->left + segment->right) / 2.0;
+
+  if (stop->offset > 0.0)
+    segment->right_color = stop->color;
+
+  /*  FIXME: remove empty segments here or add a GimpGradient API to do that
+   */
+
+  return segment;
+}
+
+static void
+svg_parse_gradient_stop_style_prop (SvgStop     *stop,
+                                    const gchar *name,
+                                    const gchar *value)
+{
+  if (strcmp (name, "stop-color") == 0)
+    {
+      gimp_rgb_parse_css (&stop->color, value, -1);
+    }
+  else if (strcmp (name, "stop-opacity") == 0)
+    {
+      gdouble opacity = g_ascii_strtod (value, NULL);
+
+      if (errno != ERANGE)
+        gimp_rgb_set_alpha (&stop->color, CLAMP (opacity, 0.0, 1.0));
+    }
+}
+
+/*  very simplistic CSS style parser  */
+static void
+svg_parse_gradient_stop_style (SvgStop     *stop,
+                               const gchar *style)
+{
+  const gchar *end;
+  const gchar *sep;
+
+  while (*style)
+    {
+      while (g_ascii_isspace (*style))
+        style++;
+
+      for (end = style; *end && *end != ';'; end++)
+        /* do nothing */;
+
+      for (sep = style; sep < end && *sep != ':'; sep++)
+        /* do nothing */;
+
+      if (end > sep && sep > style)
+        {
+          gchar *name;
+          gchar *value;
+
+          name = g_strndup (style, sep - style);
+          sep++;
+          value = g_strndup (sep, end - sep - (*end == ';' ? 1 : 0));
+
+          svg_parse_gradient_stop_style_prop (stop, name, value);
+
+          g_free (value);
+          g_free (name);
+        }
+
+      style = end;
+
+      if (*style == ';')
+        style++;
+    }
+}
+
+static SvgStop *
+svg_parse_gradient_stop (const gchar **names,
+                         const gchar **values)
+{
+  SvgStop *stop = g_slice_new0 (SvgStop);
+
+  gimp_rgb_set_alpha (&stop->color, 1.0);
+
+  while (*names && *values)
+    {
+      if (strcmp (*names, "offset") == 0)
+        {
+          gchar *end;
+
+          stop->offset = g_ascii_strtod (*values, &end);
+
+          if (end && *end == '%')
+            stop->offset /= 100.0;
+
+          stop->offset = CLAMP (stop->offset, 0.0, 1.0);
+        }
+      else if (strcmp (*names, "style") == 0)
+        {
+          svg_parse_gradient_stop_style (stop, *values);
+        }
+      else
+        {
+          svg_parse_gradient_stop_style_prop (stop, *names, *values);
+        }
+
+      names++;
+      values++;
+    }
+
+  return stop;
+}
diff --git a/app/core/gimpgradient-load.h b/app/core/gimpgradient-load.h
new file mode 100644
index 0000000..fcc648c
--- /dev/null
+++ b/app/core/gimpgradient-load.h
@@ -0,0 +1,36 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_GRADIENT_LOAD_H__
+#define __GIMP_GRADIENT_LOAD_H__
+
+
+#define GIMP_GRADIENT_FILE_EXTENSION     ".ggr"
+#define GIMP_GRADIENT_SVG_FILE_EXTENSION ".svg"
+
+
+GList  * gimp_gradient_load     (GimpContext   *context,
+                                 GFile         *file,
+                                 GInputStream  *input,
+                                 GError       **error);
+GList  * gimp_gradient_load_svg (GimpContext   *context,
+                                 GFile         *file,
+                                 GInputStream  *input,
+                                 GError       **error);
+
+
+#endif /* __GIMP_GRADIENT_LOAD_H__ */
diff --git a/app/core/gimpgradient-save.c b/app/core/gimpgradient-save.c
new file mode 100644
index 0000000..deca2d2
--- /dev/null
+++ b/app/core/gimpgradient-save.c
@@ -0,0 +1,221 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+
+#include "core-types.h"
+
+#include "gimpgradient.h"
+#include "gimpgradient-save.h"
+
+#include "gimp-intl.h"
+
+
+gboolean
+gimp_gradient_save (GimpData       *data,
+                    GOutputStream  *output,
+                    GError        **error)
+{
+  GimpGradient        *gradient = GIMP_GRADIENT (data);
+  GString             *string;
+  GimpGradientSegment *seg;
+  gint                 num_segments;
+
+  /* File format is:
+   *
+   *   GIMP Gradient
+   *   Name: name
+   *   number_of_segments
+   *   left middle right r0 g0 b0 a0 r1 g1 b1 a1 type coloring left_color_type
+   *   left middle right r0 g0 b0 a0 r1 g1 b1 a1 type coloring right_color_type
+   *   ...
+   */
+
+  string = g_string_new ("GIMP Gradient\n");
+
+  g_string_append_printf (string, "Name: %s\n",
+                          gimp_object_get_name (gradient));
+
+  /* Count number of segments */
+  num_segments = 0;
+  seg          = gradient->segments;
+
+  while (seg)
+    {
+      num_segments++;
+      seg = seg->next;
+    }
+
+  /* Write rest of file */
+  g_string_append_printf (string, "%d\n", num_segments);
+
+  for (seg = gradient->segments; seg; seg = seg->next)
+    {
+      gchar buf[11][G_ASCII_DTOSTR_BUF_SIZE];
+
+      g_ascii_dtostr (buf[0],  G_ASCII_DTOSTR_BUF_SIZE, seg->left);
+      g_ascii_dtostr (buf[1],  G_ASCII_DTOSTR_BUF_SIZE, seg->middle);
+      g_ascii_dtostr (buf[2],  G_ASCII_DTOSTR_BUF_SIZE, seg->right);
+      g_ascii_dtostr (buf[3],  G_ASCII_DTOSTR_BUF_SIZE, seg->left_color.r);
+      g_ascii_dtostr (buf[4],  G_ASCII_DTOSTR_BUF_SIZE, seg->left_color.g);
+      g_ascii_dtostr (buf[5],  G_ASCII_DTOSTR_BUF_SIZE, seg->left_color.b);
+      g_ascii_dtostr (buf[6],  G_ASCII_DTOSTR_BUF_SIZE, seg->left_color.a);
+      g_ascii_dtostr (buf[7],  G_ASCII_DTOSTR_BUF_SIZE, seg->right_color.r);
+      g_ascii_dtostr (buf[8],  G_ASCII_DTOSTR_BUF_SIZE, seg->right_color.g);
+      g_ascii_dtostr (buf[9],  G_ASCII_DTOSTR_BUF_SIZE, seg->right_color.b);
+      g_ascii_dtostr (buf[10], G_ASCII_DTOSTR_BUF_SIZE, seg->right_color.a);
+
+      g_string_append_printf (string,
+                              "%s %s %s %s %s %s %s %s %s %s %s %d %d %d %d\n",
+                              buf[0], buf[1], buf[2],   /* left, middle, right */
+                              buf[3], buf[4], buf[5], buf[6],  /* left color   */
+                              buf[7], buf[8], buf[9], buf[10], /* right color  */
+                              (gint) seg->type,
+                              (gint) seg->color,
+                              (gint) seg->left_color_type,
+                              (gint) seg->right_color_type);
+    }
+
+  if (! g_output_stream_write_all (output, string->str, string->len,
+                                   NULL, NULL, error))
+    {
+      g_string_free (string, TRUE);
+
+      return FALSE;
+    }
+
+  g_string_free (string, TRUE);
+
+  return TRUE;
+}
+
+gboolean
+gimp_gradient_save_pov (GimpGradient  *gradient,
+                        GFile         *file,
+                        GError       **error)
+{
+  GOutputStream       *output;
+  GString             *string;
+  GimpGradientSegment *seg;
+  gchar                buf[G_ASCII_DTOSTR_BUF_SIZE];
+  gchar                color_buf[4][G_ASCII_DTOSTR_BUF_SIZE];
+  GError              *my_error = NULL;
+
+  g_return_val_if_fail (GIMP_IS_GRADIENT (gradient), FALSE);
+  g_return_val_if_fail (G_IS_FILE (file), FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  output = G_OUTPUT_STREAM (g_file_replace (file,
+                                            NULL, FALSE, G_FILE_CREATE_NONE,
+                                            NULL, error));
+  if (! output)
+    return FALSE;
+
+  string = g_string_new ("/* color_map file created by GIMP */\n"
+                         "/* https://www.gimp.org/          */\n"
+                         "color_map {\n");
+
+  for (seg = gradient->segments; seg; seg = seg->next)
+    {
+      /* Left */
+      g_ascii_dtostr (buf, G_ASCII_DTOSTR_BUF_SIZE,
+                      seg->left);
+      g_ascii_dtostr (color_buf[0], G_ASCII_DTOSTR_BUF_SIZE,
+                      seg->left_color.r);
+      g_ascii_dtostr (color_buf[1], G_ASCII_DTOSTR_BUF_SIZE,
+                      seg->left_color.g);
+      g_ascii_dtostr (color_buf[2], G_ASCII_DTOSTR_BUF_SIZE,
+                      seg->left_color.b);
+      g_ascii_dtostr (color_buf[3], G_ASCII_DTOSTR_BUF_SIZE,
+                      1.0 - seg->left_color.a);
+
+      g_string_append_printf (string,
+                              "\t[%s color rgbt <%s, %s, %s, %s>]\n",
+                              buf,
+                              color_buf[0], color_buf[1],
+                              color_buf[2], color_buf[3]);
+
+      /* Middle */
+      g_ascii_dtostr (buf, G_ASCII_DTOSTR_BUF_SIZE,
+                      seg->middle);
+      g_ascii_dtostr (color_buf[0], G_ASCII_DTOSTR_BUF_SIZE,
+                      (seg->left_color.r + seg->right_color.r) / 2.0);
+      g_ascii_dtostr (color_buf[1], G_ASCII_DTOSTR_BUF_SIZE,
+                      (seg->left_color.g + seg->right_color.g) / 2.0);
+      g_ascii_dtostr (color_buf[2], G_ASCII_DTOSTR_BUF_SIZE,
+                      (seg->left_color.b + seg->right_color.b) / 2.0);
+      g_ascii_dtostr (color_buf[3], G_ASCII_DTOSTR_BUF_SIZE,
+                      1.0 - (seg->left_color.a + seg->right_color.a) / 2.0);
+
+      g_string_append_printf (string,
+                              "\t[%s color rgbt <%s, %s, %s, %s>]\n",
+                              buf,
+                              color_buf[0], color_buf[1],
+                              color_buf[2], color_buf[3]);
+
+      /* Right */
+      g_ascii_dtostr (buf, G_ASCII_DTOSTR_BUF_SIZE,
+                      seg->right);
+      g_ascii_dtostr (color_buf[0], G_ASCII_DTOSTR_BUF_SIZE,
+                      seg->right_color.r);
+      g_ascii_dtostr (color_buf[1], G_ASCII_DTOSTR_BUF_SIZE,
+                      seg->right_color.g);
+      g_ascii_dtostr (color_buf[2], G_ASCII_DTOSTR_BUF_SIZE,
+                      seg->right_color.b);
+      g_ascii_dtostr (color_buf[3], G_ASCII_DTOSTR_BUF_SIZE,
+                      1.0 - seg->right_color.a);
+
+      g_string_append_printf (string,
+                              "\t[%s color rgbt <%s, %s, %s, %s>]\n",
+                              buf,
+                              color_buf[0], color_buf[1],
+                              color_buf[2], color_buf[3]);
+    }
+
+  g_string_append_printf (string, "} /* color_map */\n");
+
+  if (! g_output_stream_write_all (output, string->str, string->len,
+                                   NULL, NULL, &my_error))
+    {
+      GCancellable *cancellable = g_cancellable_new ();
+
+      g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_WRITE,
+                   _("Writing POV file '%s' failed: %s"),
+                   gimp_file_get_utf8_name (file),
+                   my_error->message);
+      g_clear_error (&my_error);
+      g_string_free (string, TRUE);
+
+      /* Cancel the overwrite initiated by g_file_replace(). */
+      g_cancellable_cancel (cancellable);
+      g_output_stream_close (output, cancellable, NULL);
+      g_object_unref (cancellable);
+      g_object_unref (output);
+
+      return FALSE;
+    }
+
+  g_string_free (string, TRUE);
+  g_object_unref (output);
+
+  return TRUE;
+}
diff --git a/app/core/gimpgradient-save.h b/app/core/gimpgradient-save.h
new file mode 100644
index 0000000..073bdd8
--- /dev/null
+++ b/app/core/gimpgradient-save.h
@@ -0,0 +1,32 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_GRADIENT_SAVE_H__
+#define __GIMP_GRADIENT_SAVE_H__
+
+
+/*  don't call this function directly, use gimp_data_save() instead  */
+gboolean   gimp_gradient_save     (GimpData       *data,
+                                   GOutputStream  *output,
+                                   GError        **error);
+
+gboolean   gimp_gradient_save_pov (GimpGradient   *gradient,
+                                   GFile          *file,
+                                   GError        **error);
+
+
+#endif /* __GIMP_GRADIENT_SAVE_H__ */
diff --git a/app/core/gimpgradient.c b/app/core/gimpgradient.c
new file mode 100644
index 0000000..8265225
--- /dev/null
+++ b/app/core/gimpgradient.c
@@ -0,0 +1,2297 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <cairo.h>
+#include <gegl.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "libgimpcolor/gimpcolor.h"
+#include "libgimpmath/gimpmath.h"
+
+#include "core-types.h"
+
+#include "gimpcontext.h"
+#include "gimpgradient.h"
+#include "gimpgradient-load.h"
+#include "gimpgradient-save.h"
+#include "gimptagged.h"
+#include "gimptempbuf.h"
+
+
+#define EPSILON 1e-10
+
+
+static void          gimp_gradient_tagged_iface_init (GimpTaggedInterface *iface);
+static void          gimp_gradient_finalize          (GObject             *object);
+
+static gint64        gimp_gradient_get_memsize       (GimpObject          *object,
+                                                      gint64              *gui_size);
+
+static void          gimp_gradient_get_preview_size  (GimpViewable        *viewable,
+                                                      gint                 size,
+                                                      gboolean             popup,
+                                                      gboolean             dot_for_dot,
+                                                      gint                *width,
+                                                      gint                *height);
+static gboolean      gimp_gradient_get_popup_size    (GimpViewable        *viewable,
+                                                      gint                 width,
+                                                      gint                 height,
+                                                      gboolean             dot_for_dot,
+                                                      gint                *popup_width,
+                                                      gint                *popup_height);
+static GimpTempBuf * gimp_gradient_get_new_preview   (GimpViewable        *viewable,
+                                                      GimpContext         *context,
+                                                      gint                 width,
+                                                      gint                 height);
+
+static const gchar * gimp_gradient_get_extension     (GimpData            *data);
+static void          gimp_gradient_copy              (GimpData            *data,
+                                                      GimpData            *src_data);
+static gint          gimp_gradient_compare           (GimpData            *data1,
+                                                      GimpData            *data2);
+
+static gchar       * gimp_gradient_get_checksum      (GimpTagged          *tagged);
+
+static inline GimpGradientSegment *
+              gimp_gradient_get_segment_at_internal  (GimpGradient        *gradient,
+                                                      GimpGradientSegment *seg,
+                                                      gdouble              pos);
+static void          gimp_gradient_get_flat_color    (GimpContext         *context,
+                                                      const GimpRGB       *color,
+                                                      GimpGradientColor    color_type,
+                                                      GimpRGB             *flat_color);
+
+
+static inline gdouble  gimp_gradient_calc_linear_factor            (gdouble  middle,
+                                                                    gdouble  pos);
+static inline gdouble  gimp_gradient_calc_curved_factor            (gdouble  middle,
+                                                                    gdouble  pos);
+static inline gdouble  gimp_gradient_calc_sine_factor              (gdouble  middle,
+                                                                    gdouble  pos);
+static inline gdouble  gimp_gradient_calc_sphere_increasing_factor (gdouble  middle,
+                                                                    gdouble  pos);
+static inline gdouble  gimp_gradient_calc_sphere_decreasing_factor (gdouble  middle,
+                                                                    gdouble  pos);
+static inline gdouble  gimp_gradient_calc_step_factor              (gdouble  middle,
+                                                                    gdouble  pos);
+
+
+G_DEFINE_TYPE_WITH_CODE (GimpGradient, gimp_gradient, GIMP_TYPE_DATA,
+                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_TAGGED,
+                                                gimp_gradient_tagged_iface_init))
+
+#define parent_class gimp_gradient_parent_class
+
+static const Babl *fish_srgb_to_linear_rgb = NULL;
+static const Babl *fish_linear_rgb_to_srgb = NULL;
+static const Babl *fish_srgb_to_cie_lab    = NULL;
+static const Babl *fish_cie_lab_to_srgb    = NULL;
+
+
+static void
+gimp_gradient_class_init (GimpGradientClass *klass)
+{
+  GObjectClass      *object_class      = G_OBJECT_CLASS (klass);
+  GimpObjectClass   *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+  GimpViewableClass *viewable_class    = GIMP_VIEWABLE_CLASS (klass);
+  GimpDataClass     *data_class        = GIMP_DATA_CLASS (klass);
+
+  object_class->finalize            = gimp_gradient_finalize;
+
+  gimp_object_class->get_memsize    = gimp_gradient_get_memsize;
+
+  viewable_class->default_icon_name = "gimp-tool-gradient";
+  viewable_class->get_preview_size  = gimp_gradient_get_preview_size;
+  viewable_class->get_popup_size    = gimp_gradient_get_popup_size;
+  viewable_class->get_new_preview   = gimp_gradient_get_new_preview;
+
+  data_class->save                  = gimp_gradient_save;
+  data_class->get_extension         = gimp_gradient_get_extension;
+  data_class->copy                  = gimp_gradient_copy;
+  data_class->compare               = gimp_gradient_compare;
+
+  fish_srgb_to_linear_rgb = babl_fish (babl_format ("R'G'B' double"),
+                                       babl_format ("RGB double"));
+  fish_linear_rgb_to_srgb = babl_fish (babl_format ("RGB double"),
+                                       babl_format ("R'G'B' double"));
+  fish_srgb_to_cie_lab    = babl_fish (babl_format ("R'G'B' double"),
+                                       babl_format ("CIE Lab double"));
+  fish_cie_lab_to_srgb    = babl_fish (babl_format ("CIE Lab double"),
+                                       babl_format ("R'G'B' double"));
+}
+
+static void
+gimp_gradient_tagged_iface_init (GimpTaggedInterface *iface)
+{
+  iface->get_checksum = gimp_gradient_get_checksum;
+}
+
+static void
+gimp_gradient_init (GimpGradient *gradient)
+{
+  gradient->segments = NULL;
+}
+
+static void
+gimp_gradient_finalize (GObject *object)
+{
+  GimpGradient *gradient = GIMP_GRADIENT (object);
+
+  if (gradient->segments)
+    {
+      gimp_gradient_segments_free (gradient->segments);
+      gradient->segments = NULL;
+    }
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static gint64
+gimp_gradient_get_memsize (GimpObject *object,
+                           gint64     *gui_size)
+{
+  GimpGradient        *gradient = GIMP_GRADIENT (object);
+  GimpGradientSegment *segment;
+  gint64               memsize  = 0;
+
+  for (segment = gradient->segments; segment; segment = segment->next)
+    memsize += sizeof (GimpGradientSegment);
+
+  return memsize + GIMP_OBJECT_CLASS (parent_class)->get_memsize (object,
+                                                                  gui_size);
+}
+
+static void
+gimp_gradient_get_preview_size (GimpViewable *viewable,
+                                gint          size,
+                                gboolean      popup,
+                                gboolean      dot_for_dot,
+                                gint         *width,
+                                gint         *height)
+{
+  *width  = size;
+  *height = 1 + size / 2;
+}
+
+static gboolean
+gimp_gradient_get_popup_size (GimpViewable *viewable,
+                              gint          width,
+                              gint          height,
+                              gboolean      dot_for_dot,
+                              gint         *popup_width,
+                              gint         *popup_height)
+{
+  if (width < 128 || height < 32)
+    {
+      *popup_width  = 128;
+      *popup_height =  32;
+
+      return TRUE;
+    }
+
+  return FALSE;
+}
+
+static GimpTempBuf *
+gimp_gradient_get_new_preview (GimpViewable *viewable,
+                               GimpContext  *context,
+                               gint          width,
+                               gint          height)
+{
+  GimpGradient        *gradient = GIMP_GRADIENT (viewable);
+  GimpGradientSegment *seg      = NULL;
+  GimpTempBuf         *temp_buf;
+  guchar              *buf;
+  guchar              *p;
+  guchar              *row;
+  gint                 x, y;
+  gdouble              dx, cur_x;
+  GimpRGB              color;
+
+  dx    = 1.0 / (width - 1);
+  cur_x = 0.0;
+  p     = row = g_malloc (width * 4);
+
+  /* Create lines to fill the image */
+
+  for (x = 0; x < width; x++)
+    {
+      seg = gimp_gradient_get_color_at (gradient, context, seg, cur_x,
+                                        FALSE,
+                                        GIMP_GRADIENT_BLEND_RGB_PERCEPTUAL,
+                                        &color);
+
+      *p++ = ROUND (color.r * 255.0);
+      *p++ = ROUND (color.g * 255.0);
+      *p++ = ROUND (color.b * 255.0);
+      *p++ = ROUND (color.a * 255.0);
+
+      cur_x += dx;
+    }
+
+  temp_buf = gimp_temp_buf_new (width, height, babl_format ("R'G'B'A u8"));
+
+  buf = gimp_temp_buf_get_data (temp_buf);
+
+  for (y = 0; y < height; y++)
+    memcpy (buf + (width * y * 4), row, width * 4);
+
+  g_free (row);
+
+  return temp_buf;
+}
+
+static void
+gimp_gradient_copy (GimpData *data,
+                    GimpData *src_data)
+{
+  GimpGradient        *gradient     = GIMP_GRADIENT (data);
+  GimpGradient        *src_gradient = GIMP_GRADIENT (src_data);
+  GimpGradientSegment *head, *prev, *cur, *orig;
+
+  if (gradient->segments)
+    {
+      gimp_gradient_segments_free (gradient->segments);
+      gradient->segments = NULL;
+    }
+
+  prev = NULL;
+  orig = src_gradient->segments;
+  head = NULL;
+
+  while (orig)
+    {
+      cur = gimp_gradient_segment_new ();
+
+      *cur = *orig;  /* Copy everything */
+
+      cur->prev = prev;
+      cur->next = NULL;
+
+      if (prev)
+        prev->next = cur;
+      else
+        head = cur;  /* Remember head */
+
+      prev = cur;
+      orig = orig->next;
+    }
+
+  gradient->segments = head;
+
+  gimp_data_dirty (GIMP_DATA (gradient));
+}
+
+static gint
+gimp_gradient_compare (GimpData *data1,
+                       GimpData *data2)
+{
+  gboolean is_custom1;
+  gboolean is_custom2;
+
+  /* check whether data1 and data2 are the custom gradient, which is the only
+   * writable internal gradient.
+   */
+  is_custom1 = gimp_data_is_internal (data1) && gimp_data_is_writable (data1);
+  is_custom2 = gimp_data_is_internal (data2) && gimp_data_is_writable (data2);
+
+  /* order the custom gradient before all the other gradients; use the default
+   * ordering for the rest.
+   */
+  if (is_custom1)
+    {
+      if (is_custom2)
+        return 0;
+      else
+        return -1;
+    }
+  else if (is_custom2)
+    {
+      return +1;
+    }
+  else
+    return GIMP_DATA_CLASS (parent_class)->compare (data1, data2);
+}
+
+static gchar *
+gimp_gradient_get_checksum (GimpTagged *tagged)
+{
+  GimpGradient *gradient        = GIMP_GRADIENT (tagged);
+  gchar        *checksum_string = NULL;
+
+  if (gradient->segments)
+    {
+      GChecksum           *checksum = g_checksum_new (G_CHECKSUM_MD5);
+      GimpGradientSegment *segment  = gradient->segments;
+
+      while (segment)
+        {
+          g_checksum_update (checksum,
+                             (const guchar *) &segment->left,
+                             sizeof (segment->left));
+          g_checksum_update (checksum,
+                             (const guchar *) &segment->middle,
+                             sizeof (segment->middle));
+          g_checksum_update (checksum,
+                             (const guchar *) &segment->right,
+                             sizeof (segment->right));
+          g_checksum_update (checksum,
+                             (const guchar *) &segment->left_color_type,
+                             sizeof (segment->left_color_type));
+          g_checksum_update (checksum,
+                             (const guchar *) &segment->left_color,
+                             sizeof (segment->left_color));
+          g_checksum_update (checksum,
+                             (const guchar *) &segment->right_color_type,
+                             sizeof (segment->right_color_type));
+          g_checksum_update (checksum,
+                             (const guchar *) &segment->right_color,
+                             sizeof (segment->right_color));
+          g_checksum_update (checksum,
+                             (const guchar *) &segment->type,
+                             sizeof (segment->type));
+          g_checksum_update (checksum,
+                             (const guchar *) &segment->color,
+                             sizeof (segment->color));
+
+          segment = segment->next;
+        }
+
+      checksum_string = g_strdup (g_checksum_get_string (checksum));
+
+      g_checksum_free (checksum);
+    }
+
+  return checksum_string;
+}
+
+
+/*  public functions  */
+
+GimpData *
+gimp_gradient_new (GimpContext *context,
+                   const gchar *name)
+{
+  GimpGradient *gradient;
+
+  g_return_val_if_fail (name != NULL, NULL);
+  g_return_val_if_fail (*name != '\0', NULL);
+
+  gradient = g_object_new (GIMP_TYPE_GRADIENT,
+                           "name", name,
+                           NULL);
+
+  gradient->segments = gimp_gradient_segment_new ();
+
+  return GIMP_DATA (gradient);
+}
+
+GimpData *
+gimp_gradient_get_standard (GimpContext *context)
+{
+  static GimpData *standard_gradient = NULL;
+
+  if (! standard_gradient)
+    {
+      standard_gradient = gimp_gradient_new (context, "Standard");
+
+      gimp_data_clean (standard_gradient);
+      gimp_data_make_internal (standard_gradient, "gimp-gradient-standard");
+
+      g_object_add_weak_pointer (G_OBJECT (standard_gradient),
+                                 (gpointer *) &standard_gradient);
+    }
+
+  return standard_gradient;
+}
+
+static const gchar *
+gimp_gradient_get_extension (GimpData *data)
+{
+  return GIMP_GRADIENT_FILE_EXTENSION;
+}
+
+/**
+ * gimp_gradient_get_color_at:
+ * @gradient:          a gradient
+ * @context:           a context
+ * @seg:               a segment to seed the search with (or %NULL)
+ * @pos:               position in the gradient (between 0.0 and 1.0)
+ * @reverse:           when %TRUE, use the reversed gradient
+ * @blend_color_space: color space to use for blending RGB segments
+ * @color:             returns the color
+ *
+ * If you are iterating over an gradient, you should pass the the
+ * return value from the last call for @seg.
+ *
+ * Return value: the gradient segment the color is from
+ **/
+GimpGradientSegment *
+gimp_gradient_get_color_at (GimpGradient                *gradient,
+                            GimpContext                 *context,
+                            GimpGradientSegment         *seg,
+                            gdouble                      pos,
+                            gboolean                     reverse,
+                            GimpGradientBlendColorSpace  blend_color_space,
+                            GimpRGB                     *color)
+{
+  gdouble  factor = 0.0;
+  gdouble  seg_len;
+  gdouble  middle;
+  GimpRGB  left_color;
+  GimpRGB  right_color;
+  GimpRGB  rgb;
+
+  /* type-check disabled to improve speed */
+  /* g_return_val_if_fail (GIMP_IS_GRADIENT (gradient), NULL); */
+  g_return_val_if_fail (color != NULL, NULL);
+
+  pos = CLAMP (pos, 0.0, 1.0);
+
+  if (reverse)
+    pos = 1.0 - pos;
+
+  seg = gimp_gradient_get_segment_at_internal (gradient, seg, pos);
+
+  seg_len = seg->right - seg->left;
+
+  if (seg_len < EPSILON)
+    {
+      middle = 0.5;
+      pos    = 0.5;
+    }
+  else
+    {
+      middle = (seg->middle - seg->left) / seg_len;
+      pos    = (pos - seg->left) / seg_len;
+    }
+
+  switch (seg->type)
+    {
+    case GIMP_GRADIENT_SEGMENT_LINEAR:
+      factor = gimp_gradient_calc_linear_factor (middle, pos);
+      break;
+
+    case GIMP_GRADIENT_SEGMENT_CURVED:
+      factor = gimp_gradient_calc_curved_factor (middle, pos);
+      break;
+
+    case GIMP_GRADIENT_SEGMENT_SINE:
+      factor = gimp_gradient_calc_sine_factor (middle, pos);
+      break;
+
+    case GIMP_GRADIENT_SEGMENT_SPHERE_INCREASING:
+      factor = gimp_gradient_calc_sphere_increasing_factor (middle, pos);
+      break;
+
+    case GIMP_GRADIENT_SEGMENT_SPHERE_DECREASING:
+      factor = gimp_gradient_calc_sphere_decreasing_factor (middle, pos);
+      break;
+
+    case GIMP_GRADIENT_SEGMENT_STEP:
+      factor = gimp_gradient_calc_step_factor (middle, pos);
+      break;
+
+    default:
+      g_warning ("%s: Unknown gradient type %d.", G_STRFUNC, seg->type);
+      break;
+    }
+
+  /* Get left/right colors */
+
+  if (context)
+    {
+      gimp_gradient_segment_get_left_flat_color (gradient,
+                                                 context, seg, &left_color);
+
+      gimp_gradient_segment_get_right_flat_color (gradient,
+                                                  context, seg, &right_color);
+    }
+  else
+    {
+      left_color  = seg->left_color;
+      right_color = seg->right_color;
+    }
+
+  /* Calculate color components */
+
+  if (seg->color == GIMP_GRADIENT_SEGMENT_RGB)
+    {
+      switch (blend_color_space)
+        {
+        case GIMP_GRADIENT_BLEND_CIE_LAB:
+          babl_process (fish_srgb_to_cie_lab,
+                        &left_color, &left_color, 1);
+          babl_process (fish_srgb_to_cie_lab,
+                        &right_color, &right_color, 1);
+          break;
+
+        case GIMP_GRADIENT_BLEND_RGB_LINEAR:
+          babl_process (fish_srgb_to_linear_rgb,
+                        &left_color, &left_color, 1);
+          babl_process (fish_srgb_to_linear_rgb,
+                        &right_color, &right_color, 1);
+
+        case GIMP_GRADIENT_BLEND_RGB_PERCEPTUAL:
+          break;
+        }
+
+      rgb.r = left_color.r + (right_color.r - left_color.r) * factor;
+      rgb.g = left_color.g + (right_color.g - left_color.g) * factor;
+      rgb.b = left_color.b + (right_color.b - left_color.b) * factor;
+
+      switch (blend_color_space)
+        {
+        case GIMP_GRADIENT_BLEND_CIE_LAB:
+          babl_process (fish_cie_lab_to_srgb,
+                        &rgb, &rgb, 1);
+          break;
+
+        case GIMP_GRADIENT_BLEND_RGB_LINEAR:
+          babl_process (fish_linear_rgb_to_srgb,
+                        &rgb, &rgb, 1);
+
+        case GIMP_GRADIENT_BLEND_RGB_PERCEPTUAL:
+          break;
+        }
+    }
+  else
+    {
+      GimpHSV left_hsv;
+      GimpHSV right_hsv;
+
+      gimp_rgb_to_hsv (&left_color,  &left_hsv);
+      gimp_rgb_to_hsv (&right_color, &right_hsv);
+
+      left_hsv.s = left_hsv.s + (right_hsv.s - left_hsv.s) * factor;
+      left_hsv.v = left_hsv.v + (right_hsv.v - left_hsv.v) * factor;
+
+      switch (seg->color)
+        {
+        case GIMP_GRADIENT_SEGMENT_HSV_CCW:
+          if (left_hsv.h < right_hsv.h)
+            {
+              left_hsv.h += (right_hsv.h - left_hsv.h) * factor;
+            }
+          else
+            {
+              left_hsv.h += (1.0 - (left_hsv.h - right_hsv.h)) * factor;
+
+              if (left_hsv.h > 1.0)
+                left_hsv.h -= 1.0;
+            }
+          break;
+
+        case GIMP_GRADIENT_SEGMENT_HSV_CW:
+          if (right_hsv.h < left_hsv.h)
+            {
+              left_hsv.h -= (left_hsv.h - right_hsv.h) * factor;
+            }
+          else
+            {
+              left_hsv.h -= (1.0 - (right_hsv.h - left_hsv.h)) * factor;
+
+              if (left_hsv.h < 0.0)
+                left_hsv.h += 1.0;
+            }
+          break;
+
+        default:
+          g_warning ("%s: Unknown coloring mode %d",
+                     G_STRFUNC, (gint) seg->color);
+          break;
+        }
+
+      gimp_hsv_to_rgb (&left_hsv, &rgb);
+    }
+
+  /* Calculate alpha */
+
+  rgb.a = left_color.a + (right_color.a - left_color.a) * factor;
+
+  *color = rgb;
+
+  return seg;
+}
+
+GimpGradientSegment *
+gimp_gradient_get_segment_at (GimpGradient *gradient,
+                              gdouble       pos)
+{
+  g_return_val_if_fail (GIMP_IS_GRADIENT (gradient), NULL);
+
+  return gimp_gradient_get_segment_at_internal (gradient, NULL, pos);
+}
+
+gboolean
+gimp_gradient_has_fg_bg_segments (GimpGradient *gradient)
+{
+  GimpGradientSegment *segment;
+
+  g_return_val_if_fail (GIMP_IS_GRADIENT (gradient), FALSE);
+
+  for (segment = gradient->segments; segment; segment = segment->next)
+    if (segment->left_color_type  != GIMP_GRADIENT_COLOR_FIXED ||
+        segment->right_color_type != GIMP_GRADIENT_COLOR_FIXED)
+      return TRUE;
+
+  return FALSE;
+}
+
+void
+gimp_gradient_split_at (GimpGradient                 *gradient,
+                        GimpContext                  *context,
+                        GimpGradientSegment          *seg,
+                        gdouble                       pos,
+                        GimpGradientBlendColorSpace   blend_color_space,
+                        GimpGradientSegment         **newl,
+                        GimpGradientSegment         **newr)
+{
+  GimpRGB              color;
+  GimpGradientSegment *newseg;
+
+  g_return_if_fail (GIMP_IS_GRADIENT (gradient));
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  gimp_data_freeze (GIMP_DATA (gradient));
+
+  pos = CLAMP (pos, 0.0, 1.0);
+  seg = gimp_gradient_get_segment_at_internal (gradient, seg, pos);
+
+  /* Get color at pos */
+  gimp_gradient_get_color_at (gradient, context, seg, pos,
+                              FALSE, blend_color_space, &color);
+
+  /* Create a new segment and insert it in the list */
+
+  newseg = gimp_gradient_segment_new ();
+
+  newseg->prev = seg;
+  newseg->next = seg->next;
+
+  seg->next = newseg;
+
+  if (newseg->next)
+    newseg->next->prev = newseg;
+
+  /* Set coordinates of new segment */
+
+  newseg->left   = pos;
+  newseg->right  = seg->right;
+  newseg->middle = (newseg->left + newseg->right) / 2.0;
+
+  /* Set coordinates of original segment */
+
+  seg->right  = newseg->left;
+  seg->middle = (seg->left + seg->right) / 2.0;
+
+  /* Set colors of both segments */
+
+  newseg->right_color_type = seg->right_color_type;
+  newseg->right_color      = seg->right_color;
+
+  seg->right_color_type = newseg->left_color_type = GIMP_GRADIENT_COLOR_FIXED;
+  seg->right_color      = newseg->left_color      = color;
+
+  /* Set parameters of new segment */
+
+  newseg->type  = seg->type;
+  newseg->color = seg->color;
+
+  /* Done */
+
+  if (newl) *newl = seg;
+  if (newr) *newr = newseg;
+
+  gimp_data_thaw (GIMP_DATA (gradient));
+}
+
+GimpGradient *
+gimp_gradient_flatten (GimpGradient *gradient,
+                       GimpContext  *context)
+{
+  GimpGradient        *flat;
+  GimpGradientSegment *seg;
+
+  g_return_val_if_fail (GIMP_IS_GRADIENT (gradient), NULL);
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+
+  flat = GIMP_GRADIENT (gimp_data_duplicate (GIMP_DATA (gradient)));
+
+  for (seg = flat->segments; seg; seg = seg->next)
+    {
+      gimp_gradient_segment_get_left_flat_color (gradient,
+                                                 context, seg,
+                                                 &seg->left_color);
+
+      seg->left_color_type = GIMP_GRADIENT_COLOR_FIXED;
+
+      gimp_gradient_segment_get_right_flat_color (gradient,
+                                                  context, seg,
+                                                  &seg->right_color);
+
+      seg->right_color_type = GIMP_GRADIENT_COLOR_FIXED;
+    }
+
+  return flat;
+}
+
+
+/*  gradient segment functions  */
+
+GimpGradientSegment *
+gimp_gradient_segment_new (void)
+{
+  GimpGradientSegment *seg;
+
+  seg = g_slice_new0 (GimpGradientSegment);
+
+  seg->left   = 0.0;
+  seg->middle = 0.5;
+  seg->right  = 1.0;
+
+  seg->left_color_type = GIMP_GRADIENT_COLOR_FIXED;
+  gimp_rgba_set (&seg->left_color,  0.0, 0.0, 0.0, 1.0);
+
+  seg->right_color_type = GIMP_GRADIENT_COLOR_FIXED;
+  gimp_rgba_set (&seg->right_color, 1.0, 1.0, 1.0, 1.0);
+
+  seg->type  = GIMP_GRADIENT_SEGMENT_LINEAR;
+  seg->color = GIMP_GRADIENT_SEGMENT_RGB;
+
+  seg->prev = seg->next = NULL;
+
+  return seg;
+}
+
+
+void
+gimp_gradient_segment_free (GimpGradientSegment *seg)
+{
+  g_return_if_fail (seg != NULL);
+
+  g_slice_free (GimpGradientSegment, seg);
+}
+
+void
+gimp_gradient_segments_free (GimpGradientSegment *seg)
+{
+  g_return_if_fail (seg != NULL);
+
+  g_slice_free_chain (GimpGradientSegment, seg, next);
+}
+
+GimpGradientSegment *
+gimp_gradient_segment_get_last (GimpGradientSegment *seg)
+{
+  if (! seg)
+    return NULL;
+
+  while (seg->next)
+    seg = seg->next;
+
+  return seg;
+}
+
+GimpGradientSegment *
+gimp_gradient_segment_get_first (GimpGradientSegment *seg)
+{
+  if (! seg)
+    return NULL;
+
+  while (seg->prev)
+    seg = seg->prev;
+
+  return seg;
+}
+
+GimpGradientSegment *
+gimp_gradient_segment_get_nth (GimpGradientSegment *seg,
+                               gint                 index)
+{
+  gint i = 0;
+
+  g_return_val_if_fail (index >= 0, NULL);
+
+  if (! seg)
+    return NULL;
+
+  while (seg && (i < index))
+    {
+      seg = seg->next;
+      i++;
+    }
+
+  if (i == index)
+    return seg;
+
+  return NULL;
+}
+
+void
+gimp_gradient_segment_split_midpoint (GimpGradient                 *gradient,
+                                      GimpContext                  *context,
+                                      GimpGradientSegment          *lseg,
+                                      GimpGradientBlendColorSpace   blend_color_space,
+                                      GimpGradientSegment         **newl,
+                                      GimpGradientSegment         **newr)
+{
+  g_return_if_fail (GIMP_IS_GRADIENT (gradient));
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+  g_return_if_fail (lseg != NULL);
+  g_return_if_fail (newl != NULL);
+  g_return_if_fail (newr != NULL);
+
+  gimp_gradient_split_at (gradient, context, lseg, lseg->middle,
+                          blend_color_space, newl, newr);
+}
+
+void
+gimp_gradient_segment_split_uniform (GimpGradient                 *gradient,
+                                     GimpContext                  *context,
+                                     GimpGradientSegment          *lseg,
+                                     gint                          parts,
+                                     GimpGradientBlendColorSpace   blend_color_space,
+                                     GimpGradientSegment         **newl,
+                                     GimpGradientSegment         **newr)
+{
+  GimpGradientSegment *seg, *prev, *tmp;
+  gdouble              seg_len;
+  gint                 i;
+
+  g_return_if_fail (GIMP_IS_GRADIENT (gradient));
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+  g_return_if_fail (lseg != NULL);
+  g_return_if_fail (newl != NULL);
+  g_return_if_fail (newr != NULL);
+
+  gimp_data_freeze (GIMP_DATA (gradient));
+
+  seg_len = (lseg->right - lseg->left) / parts; /* Length of divisions */
+
+  seg  = NULL;
+  prev = NULL;
+  tmp  = NULL;
+
+  for (i = 0; i < parts; i++)
+    {
+      seg = gimp_gradient_segment_new ();
+
+      if (i == 0)
+        tmp = seg; /* Remember first segment */
+
+      seg->left   = lseg->left + i * seg_len;
+      seg->right  = lseg->left + (i + 1) * seg_len;
+      seg->middle = (seg->left + seg->right) / 2.0;
+
+      seg->left_color_type  = GIMP_GRADIENT_COLOR_FIXED;
+      seg->right_color_type = GIMP_GRADIENT_COLOR_FIXED;
+
+      gimp_gradient_get_color_at (gradient, context, lseg,
+                                  seg->left,  FALSE, blend_color_space,
+                                  &seg->left_color);
+      gimp_gradient_get_color_at (gradient, context, lseg,
+                                  seg->right, FALSE, blend_color_space,
+                                  &seg->right_color);
+
+      seg->type  = lseg->type;
+      seg->color = lseg->color;
+
+      seg->prev = prev;
+      seg->next = NULL;
+
+      if (prev)
+        prev->next = seg;
+
+      prev = seg;
+    }
+
+  /* Fix edges */
+
+  tmp->left_color_type = lseg->left_color_type;
+  tmp->left_color      = lseg->left_color;
+
+  seg->right_color_type = lseg->right_color_type;
+  seg->right_color      = lseg->right_color;
+
+  tmp->left  = lseg->left;
+  seg->right = lseg->right; /* To squish accumulative error */
+
+  /* Link in list */
+
+  tmp->prev = lseg->prev;
+  seg->next = lseg->next;
+
+  if (lseg->prev)
+    lseg->prev->next = tmp;
+  else
+    gradient->segments = tmp; /* We are on leftmost segment */
+
+  if (lseg->next)
+    lseg->next->prev = seg;
+
+  /* Done */
+  *newl = tmp;
+  *newr = seg;
+
+  /* Delete old segment */
+  gimp_gradient_segment_free (lseg);
+
+  gimp_data_thaw (GIMP_DATA (gradient));
+}
+
+void
+gimp_gradient_segment_get_left_color (GimpGradient        *gradient,
+                                      GimpGradientSegment *seg,
+                                      GimpRGB             *color)
+{
+  g_return_if_fail (GIMP_IS_GRADIENT (gradient));
+  g_return_if_fail (seg != NULL);
+  g_return_if_fail (color != NULL);
+
+  *color = seg->left_color;
+}
+
+void
+gimp_gradient_segment_set_left_color (GimpGradient        *gradient,
+                                      GimpGradientSegment *seg,
+                                      const GimpRGB       *color)
+{
+  g_return_if_fail (GIMP_IS_GRADIENT (gradient));
+  g_return_if_fail (seg != NULL);
+  g_return_if_fail (color != NULL);
+
+  gimp_data_freeze (GIMP_DATA (gradient));
+
+  gimp_gradient_segment_range_blend (gradient, seg, seg,
+                                     color, &seg->right_color,
+                                     TRUE, TRUE);
+
+  gimp_data_thaw (GIMP_DATA (gradient));
+}
+
+void
+gimp_gradient_segment_get_right_color (GimpGradient        *gradient,
+                                       GimpGradientSegment *seg,
+                                       GimpRGB             *color)
+{
+  g_return_if_fail (GIMP_IS_GRADIENT (gradient));
+  g_return_if_fail (seg != NULL);
+  g_return_if_fail (color != NULL);
+
+  *color = seg->right_color;
+}
+
+void
+gimp_gradient_segment_set_right_color (GimpGradient        *gradient,
+                                       GimpGradientSegment *seg,
+                                       const GimpRGB       *color)
+{
+  g_return_if_fail (GIMP_IS_GRADIENT (gradient));
+  g_return_if_fail (seg != NULL);
+  g_return_if_fail (color != NULL);
+
+  gimp_data_freeze (GIMP_DATA (gradient));
+
+  gimp_gradient_segment_range_blend (gradient, seg, seg,
+                                     &seg->left_color, color,
+                                     TRUE, TRUE);
+
+  gimp_data_thaw (GIMP_DATA (gradient));
+}
+
+GimpGradientColor
+gimp_gradient_segment_get_left_color_type (GimpGradient        *gradient,
+                                           GimpGradientSegment *seg)
+{
+  g_return_val_if_fail (GIMP_IS_GRADIENT (gradient), 0);
+  g_return_val_if_fail (seg != NULL, 0);
+
+  return seg->left_color_type;
+}
+
+void
+gimp_gradient_segment_set_left_color_type (GimpGradient        *gradient,
+                                           GimpGradientSegment *seg,
+                                           GimpGradientColor    color_type)
+{
+  g_return_if_fail (GIMP_IS_GRADIENT (gradient));
+  g_return_if_fail (seg != NULL);
+
+  gimp_data_freeze (GIMP_DATA (gradient));
+
+  seg->left_color_type = color_type;
+
+  gimp_data_thaw (GIMP_DATA (gradient));
+}
+
+GimpGradientColor
+gimp_gradient_segment_get_right_color_type (GimpGradient        *gradient,
+                                            GimpGradientSegment *seg)
+{
+  g_return_val_if_fail (GIMP_IS_GRADIENT (gradient), 0);
+  g_return_val_if_fail (seg != NULL, 0);
+
+  return seg->right_color_type;
+}
+
+void
+gimp_gradient_segment_set_right_color_type (GimpGradient        *gradient,
+                                            GimpGradientSegment *seg,
+                                            GimpGradientColor    color_type)
+{
+  g_return_if_fail (GIMP_IS_GRADIENT (gradient));
+  g_return_if_fail (seg != NULL);
+
+  gimp_data_freeze (GIMP_DATA (gradient));
+
+  seg->right_color_type = color_type;
+
+  gimp_data_thaw (GIMP_DATA (gradient));
+}
+
+void
+gimp_gradient_segment_get_left_flat_color (GimpGradient        *gradient,
+                                           GimpContext         *context,
+                                           GimpGradientSegment *seg,
+                                           GimpRGB             *color)
+{
+  g_return_if_fail (GIMP_IS_GRADIENT (gradient));
+  g_return_if_fail (seg != NULL);
+  g_return_if_fail (color != NULL);
+
+  gimp_gradient_get_flat_color (context,
+                                &seg->left_color, seg->left_color_type,
+                                color);
+}
+
+void
+gimp_gradient_segment_get_right_flat_color (GimpGradient        *gradient,
+                                            GimpContext         *context,
+                                            GimpGradientSegment *seg,
+                                            GimpRGB             *color)
+{
+  g_return_if_fail (GIMP_IS_GRADIENT (gradient));
+  g_return_if_fail (seg != NULL);
+  g_return_if_fail (color != NULL);
+
+  gimp_gradient_get_flat_color (context,
+                                &seg->right_color, seg->right_color_type,
+                                color);
+}
+
+gdouble
+gimp_gradient_segment_get_left_pos (GimpGradient        *gradient,
+                                    GimpGradientSegment *seg)
+{
+  g_return_val_if_fail (GIMP_IS_GRADIENT (gradient), 0.0);
+  g_return_val_if_fail (seg != NULL, 0.0);
+
+  return seg->left;
+}
+
+gdouble
+gimp_gradient_segment_set_left_pos (GimpGradient        *gradient,
+                                    GimpGradientSegment *seg,
+                                    gdouble              pos)
+{
+  gdouble final_pos;
+
+  g_return_val_if_fail (GIMP_IS_GRADIENT (gradient), 0.0);
+  g_return_val_if_fail (seg != NULL, 0.0);
+
+  if (seg->prev == NULL)
+    {
+      final_pos = 0;
+    }
+  else
+    {
+      gimp_data_freeze (GIMP_DATA (gradient));
+
+      final_pos = seg->prev->right = seg->left =
+          CLAMP (pos,
+                 seg->prev->middle + EPSILON,
+                 seg->middle - EPSILON);
+
+      gimp_data_thaw (GIMP_DATA (gradient));
+    }
+
+  return final_pos;
+}
+
+gdouble
+gimp_gradient_segment_get_right_pos (GimpGradient        *gradient,
+                                     GimpGradientSegment *seg)
+{
+  g_return_val_if_fail (GIMP_IS_GRADIENT (gradient), 0.0);
+  g_return_val_if_fail (seg != NULL, 0.0);
+
+  return seg->right;
+}
+
+gdouble
+gimp_gradient_segment_set_right_pos (GimpGradient        *gradient,
+                                     GimpGradientSegment *seg,
+                                     gdouble              pos)
+{
+  gdouble final_pos;
+
+  g_return_val_if_fail (GIMP_IS_GRADIENT (gradient), 0.0);
+  g_return_val_if_fail (seg != NULL, 0.0);
+
+  if (seg->next == NULL)
+    {
+      final_pos = 1.0;
+    }
+  else
+    {
+      gimp_data_freeze (GIMP_DATA (gradient));
+
+      final_pos = seg->next->left = seg->right =
+          CLAMP (pos,
+                 seg->middle + EPSILON,
+                 seg->next->middle - EPSILON);
+
+      gimp_data_thaw (GIMP_DATA (gradient));
+    }
+
+  return final_pos;
+}
+
+gdouble
+gimp_gradient_segment_get_middle_pos (GimpGradient        *gradient,
+                                      GimpGradientSegment *seg)
+{
+  g_return_val_if_fail (GIMP_IS_GRADIENT (gradient), 0.0);
+  g_return_val_if_fail (seg != NULL, 0.0);
+
+  return seg->middle;
+}
+
+gdouble
+gimp_gradient_segment_set_middle_pos (GimpGradient        *gradient,
+                                      GimpGradientSegment *seg,
+                                      gdouble              pos)
+{
+  gdouble final_pos;
+
+  g_return_val_if_fail (GIMP_IS_GRADIENT (gradient), 0.0);
+  g_return_val_if_fail (seg != NULL, 0.0);
+
+  gimp_data_freeze (GIMP_DATA (gradient));
+
+  final_pos = seg->middle =
+      CLAMP (pos,
+             seg->left + EPSILON,
+             seg->right - EPSILON);
+
+  gimp_data_thaw (GIMP_DATA (gradient));
+
+  return final_pos;
+}
+
+GimpGradientSegmentType
+gimp_gradient_segment_get_blending_function (GimpGradient        *gradient,
+                                             GimpGradientSegment *seg)
+{
+  g_return_val_if_fail (GIMP_IS_GRADIENT (gradient), 0);
+
+  return seg->type;
+}
+
+GimpGradientSegmentColor
+gimp_gradient_segment_get_coloring_type (GimpGradient        *gradient,
+                                         GimpGradientSegment *seg)
+{
+  g_return_val_if_fail (GIMP_IS_GRADIENT (gradient), 0);
+
+  return seg->color;
+}
+
+gint
+gimp_gradient_segment_range_get_n_segments (GimpGradient        *gradient,
+                                            GimpGradientSegment *range_l,
+                                            GimpGradientSegment *range_r)
+{
+  gint n_segments = 0;
+
+  g_return_val_if_fail (GIMP_IS_GRADIENT (gradient), 0);
+  g_return_val_if_fail (range_l != NULL, 0);
+
+  for (; range_l != range_r; range_l = range_l->next)
+    n_segments++;
+
+  if (range_r != NULL)
+    n_segments++;
+
+  return n_segments;
+}
+
+void
+gimp_gradient_segment_range_compress (GimpGradient        *gradient,
+                                      GimpGradientSegment *range_l,
+                                      GimpGradientSegment *range_r,
+                                      gdouble              new_l,
+                                      gdouble              new_r)
+{
+  gdouble              orig_l, orig_r;
+  GimpGradientSegment *seg, *aseg;
+
+  g_return_if_fail (GIMP_IS_GRADIENT (gradient));
+  g_return_if_fail (range_l != NULL);
+
+  gimp_data_freeze (GIMP_DATA (gradient));
+
+  if (! range_r)
+    range_r = gimp_gradient_segment_get_last (range_l);
+
+  orig_l = range_l->left;
+  orig_r = range_r->right;
+
+  if (orig_r - orig_l > EPSILON)
+    {
+      gdouble scale;
+
+      scale = (new_r - new_l) / (orig_r - orig_l);
+
+      seg = range_l;
+
+      do
+        {
+          if (seg->prev)
+            seg->left  = new_l + (seg->left - orig_l) * scale;
+          seg->middle  = new_l + (seg->middle - orig_l) * scale;
+          if (seg->next)
+            seg->right = new_l + (seg->right - orig_l) * scale;
+
+          /* Next */
+
+          aseg = seg;
+          seg  = seg->next;
+        }
+      while (aseg != range_r);
+    }
+  else
+    {
+      gint n;
+      gint i;
+
+      n = gimp_gradient_segment_range_get_n_segments (gradient,
+                                                      range_l, range_r);
+
+      for (i = 0, seg = range_l; i < n; i++, seg = seg->next)
+        {
+          if (seg->prev)
+            seg->left  = new_l + (new_r - new_l) * (i + 0.0) / n;
+          seg->middle  = new_l + (new_r - new_l) * (i + 0.5) / n;;
+          if (seg->next)
+            seg->right = new_l + (new_r - new_l) * (i + 1.0) / n;
+        }
+    }
+
+  /* Make sure that the left and right endpoints of the range are *exactly*
+   * equal to new_l and new_r; the above computations can introduce
+   * numerical inaccuracies.
+   */
+
+  range_l->left  = new_l;
+  range_l->right = new_r;
+
+  gimp_data_thaw (GIMP_DATA (gradient));
+}
+
+void
+gimp_gradient_segment_range_blend (GimpGradient        *gradient,
+                                   GimpGradientSegment *lseg,
+                                   GimpGradientSegment *rseg,
+                                   const GimpRGB       *rgb1,
+                                   const GimpRGB       *rgb2,
+                                   gboolean             blend_colors,
+                                   gboolean             blend_opacity)
+{
+  GimpRGB              d;
+  gdouble              left, len;
+  GimpGradientSegment *seg;
+  GimpGradientSegment *aseg;
+
+  g_return_if_fail (GIMP_IS_GRADIENT (gradient));
+  g_return_if_fail (lseg != NULL);
+
+  gimp_data_freeze (GIMP_DATA (gradient));
+
+  if (! rseg)
+    rseg = gimp_gradient_segment_get_last (lseg);
+
+  d.r = rgb2->r - rgb1->r;
+  d.g = rgb2->g - rgb1->g;
+  d.b = rgb2->b - rgb1->b;
+  d.a = rgb2->a - rgb1->a;
+
+  left  = lseg->left;
+  len   = rseg->right - left;
+
+  seg = lseg;
+
+  do
+    {
+      if (blend_colors)
+        {
+          seg->left_color.r  = rgb1->r + (seg->left - left) / len * d.r;
+          seg->left_color.g  = rgb1->g + (seg->left - left) / len * d.g;
+          seg->left_color.b  = rgb1->b + (seg->left - left) / len * d.b;
+
+          seg->right_color.r = rgb1->r + (seg->right - left) / len * d.r;
+          seg->right_color.g = rgb1->g + (seg->right - left) / len * d.g;
+          seg->right_color.b = rgb1->b + (seg->right - left) / len * d.b;
+        }
+
+      if (blend_opacity)
+        {
+          seg->left_color.a  = rgb1->a + (seg->left - left) / len * d.a;
+          seg->right_color.a = rgb1->a + (seg->right - left) / len * d.a;
+        }
+
+      aseg = seg;
+      seg = seg->next;
+    }
+  while (aseg != rseg);
+  gimp_data_thaw (GIMP_DATA (gradient));
+
+}
+
+void
+gimp_gradient_segment_range_set_blending_function (GimpGradient            *gradient,
+                                                   GimpGradientSegment     *start_seg,
+                                                   GimpGradientSegment     *end_seg,
+                                                   GimpGradientSegmentType  new_type)
+{
+  GimpGradientSegment *seg;
+  gboolean             reached_last_segment = FALSE;
+
+  g_return_if_fail (GIMP_IS_GRADIENT (gradient));
+
+  gimp_data_freeze (GIMP_DATA (gradient));
+
+  seg = start_seg;
+  while (seg && ! reached_last_segment)
+    {
+      if (seg == end_seg)
+        reached_last_segment = TRUE;
+
+      seg->type = new_type;
+      seg = seg->next;
+    }
+
+  gimp_data_thaw (GIMP_DATA (gradient));
+}
+
+void
+gimp_gradient_segment_range_set_coloring_type (GimpGradient             *gradient,
+                                               GimpGradientSegment      *start_seg,
+                                               GimpGradientSegment      *end_seg,
+                                               GimpGradientSegmentColor  new_color)
+{
+  GimpGradientSegment *seg;
+  gboolean             reached_last_segment = FALSE;
+
+  g_return_if_fail (GIMP_IS_GRADIENT (gradient));
+
+  gimp_data_freeze (GIMP_DATA (gradient));
+
+  seg = start_seg;
+  while (seg && ! reached_last_segment)
+    {
+      if (seg == end_seg)
+        reached_last_segment = TRUE;
+
+      seg->color = new_color;
+      seg = seg->next;
+    }
+
+  gimp_data_thaw (GIMP_DATA (gradient));
+}
+
+void
+gimp_gradient_segment_range_flip (GimpGradient         *gradient,
+                                  GimpGradientSegment  *start_seg,
+                                  GimpGradientSegment  *end_seg,
+                                  GimpGradientSegment **final_start_seg,
+                                  GimpGradientSegment **final_end_seg)
+{
+  GimpGradientSegment *oseg, *oaseg;
+  GimpGradientSegment *seg, *prev, *tmp;
+  GimpGradientSegment *lseg, *rseg;
+  gdouble              left, right;
+
+  g_return_if_fail (GIMP_IS_GRADIENT (gradient));
+
+  gimp_data_freeze (GIMP_DATA (gradient));
+
+  if (! end_seg)
+    end_seg = gimp_gradient_segment_get_last (start_seg);
+
+  left  = start_seg->left;
+  right = end_seg->right;
+
+  /* Build flipped segments */
+
+  prev = NULL;
+  oseg = end_seg;
+  tmp  = NULL;
+
+  do
+    {
+      seg = gimp_gradient_segment_new ();
+
+      if (prev == NULL)
+        {
+          seg->left = left;
+          tmp = seg; /* Remember first segment */
+        }
+      else
+        seg->left = left + right - oseg->right;
+
+      seg->middle = left + right - oseg->middle;
+      seg->right  = left + right - oseg->left;
+
+      seg->left_color_type = oseg->right_color_type;
+      seg->left_color      = oseg->right_color;
+
+      seg->right_color_type = oseg->left_color_type;
+      seg->right_color      = oseg->left_color;
+
+      switch (oseg->type)
+        {
+        case GIMP_GRADIENT_SEGMENT_SPHERE_INCREASING:
+          seg->type = GIMP_GRADIENT_SEGMENT_SPHERE_DECREASING;
+          break;
+
+        case GIMP_GRADIENT_SEGMENT_SPHERE_DECREASING:
+          seg->type = GIMP_GRADIENT_SEGMENT_SPHERE_INCREASING;
+          break;
+
+        default:
+          seg->type = oseg->type;
+        }
+
+      switch (oseg->color)
+        {
+        case GIMP_GRADIENT_SEGMENT_HSV_CCW:
+          seg->color = GIMP_GRADIENT_SEGMENT_HSV_CW;
+          break;
+
+        case GIMP_GRADIENT_SEGMENT_HSV_CW:
+          seg->color = GIMP_GRADIENT_SEGMENT_HSV_CCW;
+          break;
+
+        default:
+          seg->color = oseg->color;
+        }
+
+      seg->prev = prev;
+      seg->next = NULL;
+
+      if (prev)
+        prev->next = seg;
+
+      prev = seg;
+
+      oaseg = oseg;
+      oseg  = oseg->prev; /* Move backwards! */
+    }
+  while (oaseg != start_seg);
+
+  seg->right = right; /* Squish accumulative error */
+
+  /* Free old segments */
+
+  lseg = start_seg->prev;
+  rseg = end_seg->next;
+
+  oseg = start_seg;
+
+  do
+    {
+      oaseg = oseg->next;
+      gimp_gradient_segment_free (oseg);
+      oseg = oaseg;
+    }
+  while (oaseg != rseg);
+
+  /* Link in new segments */
+
+  if (lseg)
+    lseg->next = tmp;
+  else
+    gradient->segments = tmp;
+
+  tmp->prev = lseg;
+
+  seg->next = rseg;
+
+  if (rseg)
+    rseg->prev = seg;
+
+  /* Reset selection */
+
+  if (final_start_seg)
+    *final_start_seg = tmp;
+
+  if (final_end_seg)
+    *final_end_seg = seg;
+
+  /* Done */
+
+  gimp_data_thaw (GIMP_DATA (gradient));
+}
+
+void
+gimp_gradient_segment_range_replicate (GimpGradient         *gradient,
+                                       GimpGradientSegment  *start_seg,
+                                       GimpGradientSegment  *end_seg,
+                                       gint                  replicate_times,
+                                       GimpGradientSegment **final_start_seg,
+                                       GimpGradientSegment **final_end_seg)
+{
+  gdouble              sel_left, sel_right, sel_len;
+  gdouble              new_left;
+  gdouble              factor;
+  GimpGradientSegment *prev, *seg, *tmp;
+  GimpGradientSegment *oseg, *oaseg;
+  GimpGradientSegment *lseg, *rseg;
+  gint                 i;
+
+  g_return_if_fail (GIMP_IS_GRADIENT (gradient));
+
+  if (! end_seg)
+    end_seg = gimp_gradient_segment_get_last (start_seg);
+
+  if (replicate_times < 2)
+    {
+      *final_start_seg = start_seg;
+      *final_end_seg   = end_seg;
+      return;
+    }
+
+  gimp_data_freeze (GIMP_DATA (gradient));
+
+  /* Remember original parameters */
+  sel_left  = start_seg->left;
+  sel_right = end_seg->right;
+  sel_len   = sel_right - sel_left;
+
+  factor = 1.0 / replicate_times;
+
+  /* Build replicated segments */
+
+  prev = NULL;
+  seg  = NULL;
+  tmp  = NULL;
+
+  for (i = 0; i < replicate_times; i++)
+    {
+      /* Build one cycle */
+
+      new_left  = sel_left + i * factor * sel_len;
+
+      oseg = start_seg;
+
+      do
+        {
+          seg = gimp_gradient_segment_new ();
+
+          if (prev == NULL)
+            {
+              seg->left = sel_left;
+              tmp = seg; /* Remember first segment */
+            }
+          else
+            {
+              seg->left = new_left + factor * (oseg->left - sel_left);
+            }
+
+          seg->middle = new_left + factor * (oseg->middle - sel_left);
+          seg->right  = new_left + factor * (oseg->right - sel_left);
+
+          seg->left_color_type = oseg->left_color_type;
+          seg->left_color      = oseg->left_color;
+
+          seg->right_color_type = oseg->right_color_type;
+          seg->right_color      = oseg->right_color;
+
+          seg->type  = oseg->type;
+          seg->color = oseg->color;
+
+          seg->prev = prev;
+          seg->next = NULL;
+
+          if (prev)
+            prev->next = seg;
+
+          prev = seg;
+
+          oaseg = oseg;
+          oseg  = oseg->next;
+        }
+      while (oaseg != end_seg);
+    }
+
+  seg->right = sel_right; /* Squish accumulative error */
+
+  /* Free old segments */
+
+  lseg = start_seg->prev;
+  rseg = end_seg->next;
+
+  oseg = start_seg;
+
+  do
+    {
+      oaseg = oseg->next;
+      gimp_gradient_segment_free (oseg);
+      oseg = oaseg;
+    }
+  while (oaseg != rseg);
+
+  /* Link in new segments */
+
+  if (lseg)
+    lseg->next = tmp;
+  else
+    gradient->segments = tmp;
+
+  tmp->prev = lseg;
+
+  seg->next = rseg;
+
+  if (rseg)
+    rseg->prev = seg;
+
+  /* Reset selection */
+
+  if (final_start_seg)
+    *final_start_seg = tmp;
+
+  if (final_end_seg)
+    *final_end_seg = seg;
+
+  /* Done */
+
+  gimp_data_thaw (GIMP_DATA (gradient));
+}
+
+void
+gimp_gradient_segment_range_split_midpoint (GimpGradient                 *gradient,
+                                            GimpContext                  *context,
+                                            GimpGradientSegment          *start_seg,
+                                            GimpGradientSegment          *end_seg,
+                                            GimpGradientBlendColorSpace   blend_color_space,
+                                            GimpGradientSegment         **final_start_seg,
+                                            GimpGradientSegment         **final_end_seg)
+{
+  GimpGradientSegment *seg, *lseg, *rseg;
+
+  g_return_if_fail (GIMP_IS_GRADIENT (gradient));
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  gimp_data_freeze (GIMP_DATA (gradient));
+
+  if (! end_seg)
+    end_seg = gimp_gradient_segment_get_last (start_seg);
+
+  seg = start_seg;
+
+  do
+    {
+      gimp_gradient_segment_split_midpoint (gradient, context,
+                                            seg, blend_color_space,
+                                            &lseg, &rseg);
+      seg = rseg->next;
+    }
+  while (lseg != end_seg);
+
+  if (final_start_seg)
+    *final_start_seg = start_seg;
+
+  if (final_end_seg)
+    *final_end_seg = rseg;
+
+  gimp_data_thaw (GIMP_DATA (gradient));
+}
+
+void
+gimp_gradient_segment_range_split_uniform (GimpGradient                 *gradient,
+                                           GimpContext                  *context,
+                                           GimpGradientSegment          *start_seg,
+                                           GimpGradientSegment          *end_seg,
+                                           gint                          parts,
+                                           GimpGradientBlendColorSpace   blend_color_space,
+                                           GimpGradientSegment         **final_start_seg,
+                                           GimpGradientSegment         **final_end_seg)
+{
+  GimpGradientSegment *seg, *aseg, *lseg, *rseg, *lsel;
+
+  g_return_if_fail (GIMP_IS_GRADIENT (gradient));
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  if (! end_seg)
+    end_seg = gimp_gradient_segment_get_last (start_seg);
+
+  if (parts < 2)
+    {
+      *final_start_seg = start_seg;
+      *final_end_seg   = end_seg;
+      return;
+    }
+
+  gimp_data_freeze (GIMP_DATA (gradient));
+
+  seg = start_seg;
+  lsel = NULL;
+
+  do
+    {
+      aseg = seg;
+
+      gimp_gradient_segment_split_uniform (gradient, context, seg,
+                                           parts, blend_color_space,
+                                           &lseg, &rseg);
+
+      if (seg == start_seg)
+        lsel = lseg;
+
+      seg = rseg->next;
+    }
+  while (aseg != end_seg);
+
+  if (final_start_seg)
+    *final_start_seg = lsel;
+
+  if (final_end_seg)
+    *final_end_seg = rseg;
+
+  gimp_data_thaw (GIMP_DATA (gradient));
+}
+
+void
+gimp_gradient_segment_range_delete (GimpGradient         *gradient,
+                                    GimpGradientSegment  *start_seg,
+                                    GimpGradientSegment  *end_seg,
+                                    GimpGradientSegment **final_start_seg,
+                                    GimpGradientSegment **final_end_seg)
+{
+  GimpGradientSegment *lseg, *rseg, *seg, *aseg, *next;
+  gdouble              join;
+
+  g_return_if_fail (GIMP_IS_GRADIENT (gradient));
+
+  if (! end_seg)
+    end_seg = gimp_gradient_segment_get_last (start_seg);
+
+  /* Remember segments to the left and to the right of the selection */
+
+  lseg = start_seg->prev;
+  rseg = end_seg->next;
+
+  /* Cannot delete all the segments in the gradient */
+
+  if ((lseg == NULL) && (rseg == NULL))
+    goto premature_return;
+
+  gimp_data_freeze (GIMP_DATA (gradient));
+
+  /* Calculate join point */
+
+  join = (start_seg->left +
+          end_seg->right) / 2.0;
+
+  if (lseg == NULL)
+    join = 0.0;
+  else if (rseg == NULL)
+    join = 1.0;
+
+  /* Move segments */
+
+  if (lseg != NULL)
+    gimp_gradient_segment_range_compress (gradient, lseg, lseg,
+                                          lseg->left, join);
+
+  if (rseg != NULL)
+    gimp_gradient_segment_range_compress (gradient, rseg, rseg,
+                                          join, rseg->right);
+
+  /* Link */
+
+  if (lseg)
+    lseg->next = rseg;
+
+  if (rseg)
+    rseg->prev = lseg;
+
+  /* Delete old segments */
+
+  seg = start_seg;
+
+  do
+    {
+      next = seg->next;
+      aseg = seg;
+
+      gimp_gradient_segment_free (seg);
+
+      seg = next;
+    }
+  while (aseg != end_seg);
+
+  /* Change selection */
+
+  if (rseg)
+    {
+      if (final_start_seg)
+        *final_start_seg = rseg;
+
+      if (final_end_seg)
+        *final_end_seg = rseg;
+    }
+  else
+    {
+      if (final_start_seg)
+        *final_start_seg = lseg;
+
+      if (final_end_seg)
+        *final_end_seg = lseg;
+    }
+
+  if (lseg == NULL)
+    gradient->segments = rseg;
+
+  gimp_data_thaw (GIMP_DATA (gradient));
+
+  return;
+
+ premature_return:
+  if (final_start_seg)
+    *final_start_seg = start_seg;
+  if (final_end_seg)
+    *final_end_seg = end_seg;
+}
+
+void
+gimp_gradient_segment_range_merge (GimpGradient         *gradient,
+                                   GimpGradientSegment  *start_seg,
+                                   GimpGradientSegment  *end_seg,
+                                   GimpGradientSegment **final_start_seg,
+                                   GimpGradientSegment **final_end_seg)
+{
+  GimpGradientSegment *seg;
+
+  g_return_if_fail (GIMP_IS_GRADIENT (gradient));
+
+  if (! end_seg)
+    end_seg = gimp_gradient_segment_get_last (start_seg);
+
+  gimp_data_freeze (GIMP_DATA (gradient));
+
+  /* Copy the end segment's right position and color to the start segment */
+
+  start_seg->right            = end_seg->right;
+  start_seg->right_color_type = end_seg->right_color_type;
+  start_seg->right_color      = end_seg->right_color;
+
+  /* Center the start segment's midpoint */
+
+  start_seg->middle = (start_seg->left + start_seg->right) / 2.0;
+
+  /* Remove range segments past the start segment from the segment list */
+
+  start_seg->next = end_seg->next;
+
+  if (start_seg->next)
+    start_seg->next->prev = start_seg;
+
+  /* Merge the range's blend function and coloring type, and free the rest of
+   * the segments.
+   */
+
+  seg = end_seg;
+
+  while (seg != start_seg)
+    {
+      GimpGradientSegment *prev = seg->prev;
+
+      /* If the blend function and/or coloring type aren't uniform, reset them. */
+
+      if (seg->type != start_seg->type)
+        start_seg->type = GIMP_GRADIENT_SEGMENT_LINEAR;
+
+      if (seg->color != start_seg->color)
+        start_seg->color = GIMP_GRADIENT_SEGMENT_RGB;
+
+      gimp_gradient_segment_free (seg);
+
+      seg = prev;
+    }
+
+  if (final_start_seg)
+    *final_start_seg = start_seg;
+  if (final_end_seg)
+    *final_end_seg = start_seg;
+
+  gimp_data_thaw (GIMP_DATA (gradient));
+}
+
+void
+gimp_gradient_segment_range_recenter_handles (GimpGradient        *gradient,
+                                              GimpGradientSegment *start_seg,
+                                              GimpGradientSegment *end_seg)
+{
+  GimpGradientSegment *seg, *aseg;
+
+  g_return_if_fail (GIMP_IS_GRADIENT (gradient));
+
+  gimp_data_freeze (GIMP_DATA (gradient));
+
+  if (! end_seg)
+    end_seg = gimp_gradient_segment_get_last (start_seg);
+
+  seg = start_seg;
+
+  do
+    {
+      seg->middle = (seg->left + seg->right) / 2.0;
+
+      aseg = seg;
+      seg  = seg->next;
+    }
+  while (aseg != end_seg);
+
+  gimp_data_thaw (GIMP_DATA (gradient));
+}
+
+void
+gimp_gradient_segment_range_redistribute_handles (GimpGradient        *gradient,
+                                                  GimpGradientSegment *start_seg,
+                                                  GimpGradientSegment *end_seg)
+{
+  GimpGradientSegment *seg, *aseg;
+  gdouble              left, right, seg_len;
+  gint                 num_segs;
+  gint                 i;
+
+  g_return_if_fail (GIMP_IS_GRADIENT (gradient));
+
+  gimp_data_freeze (GIMP_DATA (gradient));
+
+  if (! end_seg)
+    end_seg = gimp_gradient_segment_get_last (start_seg);
+
+  /* Count number of segments in selection */
+
+  num_segs = 0;
+  seg      = start_seg;
+
+  do
+    {
+      num_segs++;
+      aseg = seg;
+      seg  = seg->next;
+    }
+  while (aseg != end_seg);
+
+  /* Calculate new segment length */
+
+  left    = start_seg->left;
+  right   = end_seg->right;
+  seg_len = (right - left) / num_segs;
+
+  /* Redistribute */
+
+  seg = start_seg;
+
+  for (i = 0; i < num_segs; i++)
+    {
+      seg->left   = left + i * seg_len;
+      seg->right  = left + (i + 1) * seg_len;
+      seg->middle = (seg->left + seg->right) / 2.0;
+
+      seg = seg->next;
+    }
+
+  /* Fix endpoints to squish accumulative error */
+
+  start_seg->left  = left;
+  end_seg->right = right;
+
+  gimp_data_thaw (GIMP_DATA (gradient));
+}
+
+gdouble
+gimp_gradient_segment_range_move (GimpGradient        *gradient,
+                                  GimpGradientSegment *range_l,
+                                  GimpGradientSegment *range_r,
+                                  gdouble              delta,
+                                  gboolean             control_compress)
+{
+  gdouble              lbound, rbound;
+  gint                 is_first, is_last;
+  GimpGradientSegment *seg, *aseg;
+
+  g_return_val_if_fail (GIMP_IS_GRADIENT (gradient), 0.0);
+
+  gimp_data_freeze (GIMP_DATA (gradient));
+
+  if (! range_r)
+    range_r = gimp_gradient_segment_get_last (range_l);
+
+  /* First or last segments in gradient? */
+
+  is_first = (range_l->prev == NULL);
+  is_last  = (range_r->next == NULL);
+
+  /* Calculate drag bounds */
+
+  if (! control_compress)
+    {
+      if (!is_first)
+        lbound = range_l->prev->middle + EPSILON;
+      else
+        lbound = range_l->left + EPSILON;
+
+      if (!is_last)
+        rbound = range_r->next->middle - EPSILON;
+      else
+        rbound = range_r->right - EPSILON;
+    }
+  else
+    {
+      if (!is_first)
+        lbound = range_l->prev->left + 2.0 * EPSILON;
+      else
+        lbound = range_l->left + EPSILON;
+
+      if (!is_last)
+        rbound = range_r->next->right - 2.0 * EPSILON;
+      else
+        rbound = range_r->right - EPSILON;
+    }
+
+  /* Fix the delta if necessary */
+
+  if (delta < 0.0)
+    {
+      if (!is_first)
+        {
+          if (range_l->left + delta < lbound)
+            delta = lbound - range_l->left;
+        }
+      else
+        if (range_l->middle + delta < lbound)
+          delta = lbound - range_l->middle;
+    }
+  else
+    {
+      if (!is_last)
+        {
+          if (range_r->right + delta > rbound)
+            delta = rbound - range_r->right;
+        }
+      else
+        if (range_r->middle + delta > rbound)
+          delta = rbound - range_r->middle;
+    }
+
+  /* Move all the segments inside the range */
+
+  seg = range_l;
+
+  do
+    {
+      if (!((seg == range_l) && is_first))
+        seg->left  += delta;
+
+      seg->middle  += delta;
+
+      if (!((seg == range_r) && is_last))
+        seg->right += delta;
+
+      /* Next */
+
+      aseg = seg;
+      seg  = seg->next;
+    }
+  while (aseg != range_r);
+
+  /* Fix the segments that surround the range */
+
+  if (!is_first)
+    {
+      if (! control_compress)
+        range_l->prev->right = range_l->left;
+      else
+        gimp_gradient_segment_range_compress (gradient,
+                                              range_l->prev, range_l->prev,
+                                              range_l->prev->left, range_l->left);
+    }
+
+  if (!is_last)
+    {
+      if (! control_compress)
+        range_r->next->left = range_r->right;
+      else
+        gimp_gradient_segment_range_compress (gradient,
+                                              range_r->next, range_r->next,
+                                              range_r->right, range_r->next->right);
+    }
+
+  gimp_data_thaw (GIMP_DATA (gradient));
+
+  return delta;
+}
+
+
+/*  private functions  */
+
+static inline GimpGradientSegment *
+gimp_gradient_get_segment_at_internal (GimpGradient        *gradient,
+                                       GimpGradientSegment *seg,
+                                       gdouble              pos)
+{
+  /* handle FP imprecision at the edges of the gradient */
+  pos = CLAMP (pos, 0.0, 1.0);
+
+  if (! seg)
+    seg = gradient->segments;
+
+  if (pos >= seg->left)
+    {
+      while (seg->next && pos >= seg->right)
+        seg = seg->next;
+    }
+  else
+    {
+      do
+        seg = seg->prev;
+      while (pos < seg->left);
+    }
+
+  return seg;
+}
+
+static void
+gimp_gradient_get_flat_color (GimpContext       *context,
+                              const GimpRGB     *color,
+                              GimpGradientColor  color_type,
+                              GimpRGB           *flat_color)
+{
+  switch (color_type)
+    {
+    case GIMP_GRADIENT_COLOR_FIXED:
+      *flat_color = *color;
+      break;
+
+    case GIMP_GRADIENT_COLOR_FOREGROUND:
+    case GIMP_GRADIENT_COLOR_FOREGROUND_TRANSPARENT:
+      gimp_context_get_foreground (context, flat_color);
+
+      if (color_type == GIMP_GRADIENT_COLOR_FOREGROUND_TRANSPARENT)
+        gimp_rgb_set_alpha (flat_color, 0.0);
+      break;
+
+    case GIMP_GRADIENT_COLOR_BACKGROUND:
+    case GIMP_GRADIENT_COLOR_BACKGROUND_TRANSPARENT:
+      gimp_context_get_background (context, flat_color);
+
+      if (color_type == GIMP_GRADIENT_COLOR_BACKGROUND_TRANSPARENT)
+        gimp_rgb_set_alpha (flat_color, 0.0);
+      break;
+    }
+}
+
+static inline gdouble
+gimp_gradient_calc_linear_factor (gdouble middle,
+                                  gdouble pos)
+{
+  if (pos <= middle)
+    {
+      if (middle < EPSILON)
+        return 0.0;
+      else
+        return 0.5 * pos / middle;
+    }
+  else
+    {
+      pos -= middle;
+      middle = 1.0 - middle;
+
+      if (middle < EPSILON)
+        return 1.0;
+      else
+        return 0.5 + 0.5 * pos / middle;
+    }
+}
+
+static inline gdouble
+gimp_gradient_calc_curved_factor (gdouble middle,
+                                  gdouble pos)
+{
+  if (middle < EPSILON)
+    return 1.0;
+  else if (1.0 - middle < EPSILON)
+    return 0.0;
+
+  return exp (-G_LN2 * log (pos) / log (middle));
+}
+
+static inline gdouble
+gimp_gradient_calc_sine_factor (gdouble middle,
+                                gdouble pos)
+{
+  pos = gimp_gradient_calc_linear_factor (middle, pos);
+
+  return (sin ((-G_PI / 2.0) + G_PI * pos) + 1.0) / 2.0;
+}
+
+static inline gdouble
+gimp_gradient_calc_sphere_increasing_factor (gdouble middle,
+                                             gdouble pos)
+{
+  pos = gimp_gradient_calc_linear_factor (middle, pos) - 1.0;
+
+  /* Works for convex increasing and concave decreasing */
+  return sqrt (1.0 - pos * pos);
+}
+
+static inline gdouble
+gimp_gradient_calc_sphere_decreasing_factor (gdouble middle,
+                                             gdouble pos)
+{
+  pos = gimp_gradient_calc_linear_factor (middle, pos);
+
+  /* Works for convex decreasing and concave increasing */
+  return 1.0 - sqrt(1.0 - pos * pos);
+}
+
+static inline gdouble
+gimp_gradient_calc_step_factor (gdouble middle,
+                                gdouble pos)
+{
+  return pos >= middle;
+}
diff --git a/app/core/gimpgradient.h b/app/core/gimpgradient.h
new file mode 100644
index 0000000..8aa817d
--- /dev/null
+++ b/app/core/gimpgradient.h
@@ -0,0 +1,296 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_GRADIENT_H__
+#define __GIMP_GRADIENT_H__
+
+
+#include "gimpdata.h"
+
+
+#define GIMP_GRADIENT_DEFAULT_SAMPLE_SIZE 40
+
+
+struct _GimpGradientSegment
+{
+  gdouble                  left, middle, right;
+
+  GimpGradientColor        left_color_type;
+  GimpRGB                  left_color;
+  GimpGradientColor        right_color_type;
+  GimpRGB                  right_color;
+
+  GimpGradientSegmentType  type;          /*  Segment's blending function  */
+  GimpGradientSegmentColor color;         /*  Segment's coloring type      */
+
+  GimpGradientSegment     *prev;
+  GimpGradientSegment     *next;
+};
+
+
+#define GIMP_TYPE_GRADIENT            (gimp_gradient_get_type ())
+#define GIMP_GRADIENT(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_GRADIENT, GimpGradient))
+#define GIMP_GRADIENT_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_GRADIENT, GimpGradientClass))
+#define GIMP_IS_GRADIENT(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_GRADIENT))
+#define GIMP_IS_GRADIENT_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_GRADIENT))
+#define GIMP_GRADIENT_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_GRADIENT, GimpGradientClass))
+
+
+typedef struct _GimpGradientClass GimpGradientClass;
+
+struct _GimpGradient
+{
+  GimpData             parent_instance;
+
+  GimpGradientSegment *segments;
+};
+
+struct _GimpGradientClass
+{
+  GimpDataClass  parent_class;
+};
+
+
+GType                 gimp_gradient_get_type       (void) G_GNUC_CONST;
+
+GimpData            * gimp_gradient_new            (GimpContext   *context,
+                                                    const gchar   *name);
+GimpData            * gimp_gradient_get_standard   (GimpContext   *context);
+
+GimpGradientSegment * gimp_gradient_get_color_at   (GimpGradient        *gradient,
+                                                    GimpContext         *context,
+                                                    GimpGradientSegment *seg,
+                                                    gdouble              pos,
+                                                    gboolean             reverse,
+                                                    GimpGradientBlendColorSpace blend_color_space,
+                                                    GimpRGB             *color);
+GimpGradientSegment * gimp_gradient_get_segment_at (GimpGradient  *grad,
+                                                    gdouble        pos);
+void                  gimp_gradient_split_at       (GimpGradient         *gradient,
+                                                    GimpContext          *context,
+                                                    GimpGradientSegment  *seg,
+                                                    gdouble               pos,
+                                                    GimpGradientBlendColorSpace blend_color_space,
+                                                    GimpGradientSegment **newl,
+                                                    GimpGradientSegment **newr);
+
+gboolean          gimp_gradient_has_fg_bg_segments (GimpGradient  *gradient);
+GimpGradient    * gimp_gradient_flatten            (GimpGradient  *gradient,
+                                                    GimpContext   *context);
+
+
+/*  gradient segment functions  */
+
+GimpGradientSegment * gimp_gradient_segment_new       (void);
+GimpGradientSegment * gimp_gradient_segment_get_last  (GimpGradientSegment *seg);
+GimpGradientSegment * gimp_gradient_segment_get_first (GimpGradientSegment *seg);
+GimpGradientSegment * gimp_gradient_segment_get_nth   (GimpGradientSegment *seg,
+                                                       gint                 index);
+
+void                  gimp_gradient_segment_free      (GimpGradientSegment *seg);
+void                  gimp_gradient_segments_free     (GimpGradientSegment *seg);
+
+void    gimp_gradient_segment_split_midpoint  (GimpGradient         *gradient,
+                                               GimpContext          *context,
+                                               GimpGradientSegment  *lseg,
+                                               GimpGradientBlendColorSpace blend_color_space,
+                                               GimpGradientSegment **newl,
+                                               GimpGradientSegment **newr);
+void    gimp_gradient_segment_split_uniform   (GimpGradient         *gradient,
+                                               GimpContext          *context,
+                                               GimpGradientSegment  *lseg,
+                                               gint                  parts,
+                                               GimpGradientBlendColorSpace blend_color_space,
+                                               GimpGradientSegment **newl,
+                                               GimpGradientSegment **newr);
+
+/* Colors Setting/Getting Routines */
+void    gimp_gradient_segment_get_left_color  (GimpGradient         *gradient,
+                                               GimpGradientSegment  *seg,
+                                               GimpRGB              *color);
+
+void    gimp_gradient_segment_set_left_color  (GimpGradient         *gradient,
+                                               GimpGradientSegment  *seg,
+                                               const GimpRGB        *color);
+
+
+void    gimp_gradient_segment_get_right_color (GimpGradient         *gradient,
+                                               GimpGradientSegment  *seg,
+                                               GimpRGB              *color);
+
+void    gimp_gradient_segment_set_right_color (GimpGradient         *gradient,
+                                               GimpGradientSegment  *seg,
+                                               const GimpRGB        *color);
+
+
+GimpGradientColor
+gimp_gradient_segment_get_left_color_type     (GimpGradient         *gradient,
+                                               GimpGradientSegment  *seg);
+
+void
+gimp_gradient_segment_set_left_color_type     (GimpGradient         *gradient,
+                                               GimpGradientSegment  *seg,
+                                               GimpGradientColor     color_type);
+
+
+GimpGradientColor
+gimp_gradient_segment_get_right_color_type    (GimpGradient         *gradient,
+                                               GimpGradientSegment  *seg);
+
+void
+gimp_gradient_segment_set_right_color_type    (GimpGradient         *gradient,
+                                               GimpGradientSegment  *seg,
+                                               GimpGradientColor     color_type);
+
+
+void
+gimp_gradient_segment_get_left_flat_color     (GimpGradient         *gradient,
+                                               GimpContext          *context,
+                                               GimpGradientSegment  *seg,
+                                               GimpRGB              *color);
+
+
+void
+gimp_gradient_segment_get_right_flat_color    (GimpGradient         *gradient,
+                                               GimpContext          *context,
+                                               GimpGradientSegment  *seg,
+                                               GimpRGB              *color);
+
+
+/* Position Setting/Getting Routines */
+/* (Setters return the position after it was set) */
+gdouble gimp_gradient_segment_get_left_pos    (GimpGradient         *gradient,
+                                               GimpGradientSegment  *seg);
+gdouble gimp_gradient_segment_set_left_pos    (GimpGradient         *gradient,
+                                               GimpGradientSegment  *seg,
+                                               gdouble               pos);
+
+gdouble gimp_gradient_segment_get_right_pos   (GimpGradient         *gradient,
+                                               GimpGradientSegment  *seg);
+gdouble gimp_gradient_segment_set_right_pos   (GimpGradient         *gradient,
+                                               GimpGradientSegment  *seg,
+                                               gdouble               pos);
+
+gdouble gimp_gradient_segment_get_middle_pos  (GimpGradient         *gradient,
+                                               GimpGradientSegment  *seg);
+gdouble gimp_gradient_segment_set_middle_pos  (GimpGradient         *gradient,
+                                               GimpGradientSegment  *seg,
+                                               gdouble               pos);
+
+/* Getting/Setting the Blending Function/Coloring Type */
+GimpGradientSegmentType
+gimp_gradient_segment_get_blending_function   (GimpGradient         *gradient,
+                                               GimpGradientSegment  *seg);
+GimpGradientSegmentColor
+gimp_gradient_segment_get_coloring_type       (GimpGradient         *gradient,
+                                               GimpGradientSegment  *seg);
+
+/*
+ * If the second segment is NULL, these functions will process
+ * until the end of the string.
+ * */
+gint    gimp_gradient_segment_range_get_n_segments
+                                              (GimpGradient         *gradient,
+                                               GimpGradientSegment  *range_l,
+                                               GimpGradientSegment  *range_r);
+
+void    gimp_gradient_segment_range_compress  (GimpGradient         *gradient,
+                                               GimpGradientSegment  *range_l,
+                                               GimpGradientSegment  *range_r,
+                                               gdouble               new_l,
+                                               gdouble               new_r);
+void    gimp_gradient_segment_range_blend     (GimpGradient         *gradient,
+                                               GimpGradientSegment  *lseg,
+                                               GimpGradientSegment  *rseg,
+                                               const GimpRGB        *rgb1,
+                                               const GimpRGB        *rgb2,
+                                               gboolean              blend_colors,
+                                               gboolean              blend_opacity);
+
+void    gimp_gradient_segment_range_set_blending_function
+                                              (GimpGradient         *gradient,
+                                               GimpGradientSegment  *start_seg,
+                                               GimpGradientSegment  *end_seg,
+                                               GimpGradientSegmentType new_type);
+
+void    gimp_gradient_segment_range_set_coloring_type
+                                              (GimpGradient         *gradient,
+                                               GimpGradientSegment  *start_seg,
+                                               GimpGradientSegment  *end_seg,
+                                               GimpGradientSegmentColor new_color);
+
+void    gimp_gradient_segment_range_flip      (GimpGradient         *gradient,
+                                               GimpGradientSegment  *start_seg,
+                                               GimpGradientSegment  *end_seg,
+                                               GimpGradientSegment **final_start_seg,
+                                               GimpGradientSegment **final_end_seg);
+
+void    gimp_gradient_segment_range_replicate (GimpGradient         *gradient,
+                                               GimpGradientSegment  *start_seg,
+                                               GimpGradientSegment  *end_seg,
+                                               gint                  replicate_times,
+                                               GimpGradientSegment **final_start_seg,
+                                               GimpGradientSegment **final_end_seg);
+
+void    gimp_gradient_segment_range_split_midpoint
+                                              (GimpGradient         *gradient,
+                                               GimpContext          *context,
+                                               GimpGradientSegment  *start_seg,
+                                               GimpGradientSegment  *end_seg,
+                                               GimpGradientBlendColorSpace blend_color_space,
+                                               GimpGradientSegment **final_start_seg,
+                                               GimpGradientSegment **final_end_seg);
+
+void    gimp_gradient_segment_range_split_uniform
+                                              (GimpGradient         *gradient,
+                                               GimpContext          *context,
+                                               GimpGradientSegment  *start_seg,
+                                               GimpGradientSegment  *end_seg,
+                                               gint                  parts,
+                                               GimpGradientBlendColorSpace blend_color_space,
+                                               GimpGradientSegment **final_start_seg,
+                                               GimpGradientSegment **final_end_seg);
+
+void    gimp_gradient_segment_range_delete    (GimpGradient         *gradient,
+                                               GimpGradientSegment  *start_seg,
+                                               GimpGradientSegment  *end_seg,
+                                               GimpGradientSegment **final_start_seg,
+                                               GimpGradientSegment **final_end_seg);
+
+void    gimp_gradient_segment_range_merge     (GimpGradient         *gradient,
+                                               GimpGradientSegment  *start_seg,
+                                               GimpGradientSegment  *end_seg,
+                                               GimpGradientSegment **final_start_seg,
+                                               GimpGradientSegment **final_end_seg);
+
+void    gimp_gradient_segment_range_recenter_handles
+                                              (GimpGradient         *gradient,
+                                               GimpGradientSegment  *start_seg,
+                                               GimpGradientSegment  *end_seg);
+void    gimp_gradient_segment_range_redistribute_handles
+                                              (GimpGradient         *gradient,
+                                               GimpGradientSegment  *start_seg,
+                                               GimpGradientSegment  *end_seg);
+
+gdouble gimp_gradient_segment_range_move      (GimpGradient         *gradient,
+                                               GimpGradientSegment  *range_l,
+                                               GimpGradientSegment  *range_r,
+                                               gdouble               delta,
+                                               gboolean              control_compress);
+
+
+#endif /* __GIMP_GRADIENT_H__ */
diff --git a/app/core/gimpgrid.c b/app/core/gimpgrid.c
new file mode 100644
index 0000000..d500113
--- /dev/null
+++ b/app/core/gimpgrid.c
@@ -0,0 +1,359 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * GimpGrid
+ * Copyright (C) 2003  Henrik Brix Andersen <brix@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <cairo.h>
+#include <gegl.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "libgimpmath/gimpmath.h"
+#include "libgimpbase/gimpbase.h"
+#include "libgimpconfig/gimpconfig.h"
+
+#include "libgimpcolor/gimpcolor.h"
+
+#include "core-types.h"
+
+#include "gimpgrid.h"
+
+#include "gimp-intl.h"
+
+
+enum
+{
+  PROP_0,
+  PROP_STYLE,
+  PROP_FGCOLOR,
+  PROP_BGCOLOR,
+  PROP_XSPACING,
+  PROP_YSPACING,
+  PROP_SPACING_UNIT,
+  PROP_XOFFSET,
+  PROP_YOFFSET,
+  PROP_OFFSET_UNIT
+};
+
+
+static void   gimp_grid_get_property (GObject      *object,
+                                      guint         property_id,
+                                      GValue       *value,
+                                      GParamSpec   *pspec);
+static void   gimp_grid_set_property (GObject      *object,
+                                      guint         property_id,
+                                      const GValue *value,
+                                      GParamSpec   *pspec);
+
+
+G_DEFINE_TYPE_WITH_CODE (GimpGrid, gimp_grid, GIMP_TYPE_OBJECT,
+                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_CONFIG, NULL))
+
+
+static void
+gimp_grid_class_init (GimpGridClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+  GimpRGB       black;
+  GimpRGB       white;
+
+  object_class->get_property = gimp_grid_get_property;
+  object_class->set_property = gimp_grid_set_property;
+
+  gimp_rgba_set (&black, 0.0, 0.0, 0.0, GIMP_OPACITY_OPAQUE);
+  gimp_rgba_set (&white, 1.0, 1.0, 1.0, GIMP_OPACITY_OPAQUE);
+
+  GIMP_CONFIG_PROP_ENUM (object_class, PROP_STYLE,
+                         "style",
+                         _("Line style"),
+                         _("Line style used for the grid."),
+                         GIMP_TYPE_GRID_STYLE,
+                         GIMP_GRID_SOLID,
+                         GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_RGB (object_class, PROP_FGCOLOR,
+                        "fgcolor",
+                        _("Foreground color"),
+                        _("The foreground color of the grid."),
+                        TRUE, &black,
+                        GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_RGB (object_class, PROP_BGCOLOR,
+                        "bgcolor",
+                        _("Background color"),
+                        _("The background color of the grid; "
+                          "only used in double dashed line style."),
+                        TRUE, &white,
+                        GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_DOUBLE (object_class, PROP_XSPACING,
+                           "xspacing",
+                           _("Spacing X"),
+                           _("Horizontal spacing of grid lines."),
+                           0.0, GIMP_MAX_IMAGE_SIZE, 10.0,
+                           GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_DOUBLE (object_class, PROP_YSPACING,
+                           "yspacing",
+                           _("Spacing Y"),
+                           _("Vertical spacing of grid lines."),
+                           0.0, GIMP_MAX_IMAGE_SIZE, 10.0,
+                           GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_UNIT (object_class, PROP_SPACING_UNIT,
+                         "spacing-unit",
+                         _("Spacing unit"),
+                         NULL,
+                         FALSE, FALSE, GIMP_UNIT_INCH,
+                         GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_DOUBLE (object_class, PROP_XOFFSET,
+                           "xoffset",
+                           _("Offset X"),
+                           _("Horizontal offset of the first grid "
+                             "line; this may be a negative number."),
+                           - GIMP_MAX_IMAGE_SIZE,
+                           GIMP_MAX_IMAGE_SIZE, 0.0,
+                           GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_DOUBLE (object_class, PROP_YOFFSET,
+                           "yoffset",
+                           _("Offset Y"),
+                           _("Vertical offset of the first grid "
+                             "line; this may be a negative number."),
+                           - GIMP_MAX_IMAGE_SIZE,
+                           GIMP_MAX_IMAGE_SIZE, 0.0,
+                           GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_UNIT (object_class, PROP_OFFSET_UNIT,
+                         "offset-unit",
+                         _("Offset unit"),
+                         NULL,
+                         FALSE, FALSE, GIMP_UNIT_INCH,
+                         GIMP_PARAM_STATIC_STRINGS);
+}
+
+static void
+gimp_grid_init (GimpGrid *grid)
+{
+}
+
+static void
+gimp_grid_get_property (GObject      *object,
+                        guint         property_id,
+                        GValue       *value,
+                        GParamSpec   *pspec)
+{
+  GimpGrid *grid = GIMP_GRID (object);
+
+  switch (property_id)
+    {
+    case PROP_STYLE:
+      g_value_set_enum (value, grid->style);
+      break;
+    case PROP_FGCOLOR:
+      g_value_set_boxed (value, &grid->fgcolor);
+      break;
+    case PROP_BGCOLOR:
+      g_value_set_boxed (value, &grid->bgcolor);
+      break;
+    case PROP_XSPACING:
+      g_value_set_double (value, grid->xspacing);
+      break;
+    case PROP_YSPACING:
+      g_value_set_double (value, grid->yspacing);
+      break;
+    case PROP_SPACING_UNIT:
+      g_value_set_int (value, grid->spacing_unit);
+      break;
+    case PROP_XOFFSET:
+      g_value_set_double (value, grid->xoffset);
+      break;
+    case PROP_YOFFSET:
+      g_value_set_double (value, grid->yoffset);
+      break;
+    case PROP_OFFSET_UNIT:
+      g_value_set_int (value, grid->offset_unit);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_grid_set_property (GObject      *object,
+                        guint         property_id,
+                        const GValue *value,
+                        GParamSpec   *pspec)
+{
+  GimpGrid *grid = GIMP_GRID (object);
+  GimpRGB  *color;
+
+  switch (property_id)
+    {
+    case PROP_STYLE:
+      grid->style = g_value_get_enum (value);
+      break;
+    case PROP_FGCOLOR:
+      color = g_value_get_boxed (value);
+      grid->fgcolor = *color;
+      break;
+    case PROP_BGCOLOR:
+      color = g_value_get_boxed (value);
+      grid->bgcolor = *color;
+      break;
+    case PROP_XSPACING:
+      grid->xspacing = g_value_get_double (value);
+      break;
+    case PROP_YSPACING:
+      grid->yspacing = g_value_get_double (value);
+      break;
+    case PROP_SPACING_UNIT:
+      grid->spacing_unit = g_value_get_int (value);
+      break;
+    case PROP_XOFFSET:
+      grid->xoffset = g_value_get_double (value);
+      break;
+    case PROP_YOFFSET:
+      grid->yoffset = g_value_get_double (value);
+      break;
+    case PROP_OFFSET_UNIT:
+      grid->offset_unit = g_value_get_int (value);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+
+/*  public functions  */
+
+GimpGridStyle
+gimp_grid_get_style (GimpGrid *grid)
+{
+  g_return_val_if_fail (GIMP_IS_GRID (grid), GIMP_GRID_SOLID);
+
+  return grid->style;
+}
+
+void
+gimp_grid_get_fgcolor (GimpGrid *grid,
+                       GimpRGB  *fgcolor)
+{
+  g_return_if_fail (GIMP_IS_GRID (grid));
+  g_return_if_fail (fgcolor != NULL);
+
+  *fgcolor = grid->fgcolor;
+}
+
+void
+gimp_grid_get_bgcolor (GimpGrid *grid,
+                       GimpRGB  *bgcolor)
+{
+  g_return_if_fail (GIMP_IS_GRID (grid));
+  g_return_if_fail (bgcolor != NULL);
+
+  *bgcolor = grid->bgcolor;
+}
+
+void
+gimp_grid_get_spacing (GimpGrid *grid,
+                       gdouble  *xspacing,
+                       gdouble  *yspacing)
+{
+  g_return_if_fail (GIMP_IS_GRID (grid));
+
+  if (xspacing) *xspacing = grid->xspacing;
+  if (yspacing) *yspacing = grid->yspacing;
+}
+
+void
+gimp_grid_get_offset (GimpGrid *grid,
+                      gdouble  *xoffset,
+                      gdouble  *yoffset)
+{
+  g_return_if_fail (GIMP_IS_GRID (grid));
+
+  if (xoffset) *xoffset = grid->xoffset;
+  if (yoffset) *yoffset = grid->yoffset;
+}
+
+const gchar *
+gimp_grid_parasite_name (void)
+{
+  return "gimp-image-grid";
+}
+
+GimpParasite *
+gimp_grid_to_parasite (GimpGrid *grid)
+{
+  GimpParasite *parasite;
+  gchar        *str;
+
+  g_return_val_if_fail (GIMP_IS_GRID (grid), NULL);
+
+  str = gimp_config_serialize_to_string (GIMP_CONFIG (grid), NULL);
+  g_return_val_if_fail (str != NULL, NULL);
+
+  parasite = gimp_parasite_new (gimp_grid_parasite_name (),
+                                GIMP_PARASITE_PERSISTENT,
+                                strlen (str) + 1, str);
+  g_free (str);
+
+  return parasite;
+}
+
+GimpGrid *
+gimp_grid_from_parasite (const GimpParasite *parasite)
+{
+  GimpGrid    *grid;
+  const gchar *str;
+  GError      *error = NULL;
+
+  g_return_val_if_fail (parasite != NULL, NULL);
+  g_return_val_if_fail (strcmp (gimp_parasite_name (parasite),
+                                gimp_grid_parasite_name ()) == 0, NULL);
+
+  str = gimp_parasite_data (parasite);
+
+  if (! str)
+    {
+      g_warning ("Empty grid parasite");
+
+      return NULL;
+    }
+
+  grid = g_object_new (GIMP_TYPE_GRID, NULL);
+
+  if (! gimp_config_deserialize_string (GIMP_CONFIG (grid),
+                                        str,
+                                        gimp_parasite_data_size (parasite),
+                                        NULL,
+                                        &error))
+    {
+      g_warning ("Failed to deserialize grid parasite: %s", error->message);
+      g_error_free (error);
+    }
+
+  return grid;
+}
diff --git a/app/core/gimpgrid.h b/app/core/gimpgrid.h
new file mode 100644
index 0000000..b7d45b2
--- /dev/null
+++ b/app/core/gimpgrid.h
@@ -0,0 +1,81 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * GimpGrid
+ * Copyright (C) 2003  Henrik Brix Andersen <brix@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_GRID_H__
+#define __GIMP_GRID_H__
+
+
+#include "gimpobject.h"
+
+
+#define GIMP_TYPE_GRID            (gimp_grid_get_type ())
+#define GIMP_GRID(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_GRID, GimpGrid))
+#define GIMP_GRID_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_GRID, GimpGridClass))
+#define GIMP_IS_GRID(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_GRID))
+#define GIMP_IS_GRID_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_GRID))
+#define GIMP_GRID_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_GRID, GimpGridClass))
+
+
+typedef struct _GimpGridClass  GimpGridClass;
+
+struct _GimpGrid
+{
+  GimpObject     parent_instance;
+
+  GimpGridStyle  style;
+  GimpRGB        fgcolor;
+  GimpRGB        bgcolor;
+  gdouble        xspacing;
+  gdouble        yspacing;
+  GimpUnit       spacing_unit;
+  gdouble        xoffset;
+  gdouble        yoffset;
+  GimpUnit       offset_unit;
+};
+
+
+struct _GimpGridClass
+{
+  GimpObjectClass  parent_class;
+};
+
+
+GType          gimp_grid_get_type               (void) G_GNUC_CONST;
+
+GimpGridStyle  gimp_grid_get_style              (GimpGrid           *grid);
+
+void           gimp_grid_get_fgcolor            (GimpGrid           *grid,
+                                                 GimpRGB            *fgcolor);
+void           gimp_grid_get_bgcolor            (GimpGrid           *grid,
+                                                 GimpRGB            *bgcolor);
+
+void           gimp_grid_get_spacing            (GimpGrid           *grid,
+                                                 gdouble            *xspacing,
+                                                 gdouble            *yspacing);
+void           gimp_grid_get_offset             (GimpGrid           *grid,
+                                                 gdouble            *xoffset,
+                                                 gdouble            *yoffset);
+
+const gchar  * gimp_grid_parasite_name          (void) G_GNUC_CONST;
+GimpParasite * gimp_grid_to_parasite            (GimpGrid           *grid);
+GimpGrid     * gimp_grid_from_parasite          (const GimpParasite *parasite);
+
+
+#endif /* __GIMP_GRID_H__ */
diff --git a/app/core/gimpgrouplayer.c b/app/core/gimpgrouplayer.c
new file mode 100644
index 0000000..b0de646
--- /dev/null
+++ b/app/core/gimpgrouplayer.c
@@ -0,0 +1,2297 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * GimpGroupLayer
+ * Copyright (C) 2009  Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpmath/gimpmath.h"
+
+#include "core-types.h"
+
+#include "gegl/gimp-babl.h"
+#include "gegl/gimp-gegl-loops.h"
+
+#include "gimpdrawable-filters.h"
+#include "gimpgrouplayer.h"
+#include "gimpgrouplayerundo.h"
+#include "gimpimage.h"
+#include "gimpimage-undo.h"
+#include "gimpimage-undo-push.h"
+#include "gimplayerstack.h"
+#include "gimpobjectqueue.h"
+#include "gimppickable.h"
+#include "gimpprogress.h"
+#include "gimpprojectable.h"
+#include "gimpprojection.h"
+
+#include "gimp-intl.h"
+
+
+typedef struct _GimpGroupLayerPrivate GimpGroupLayerPrivate;
+
+struct _GimpGroupLayerPrivate
+{
+  GimpContainer  *children;
+  GimpProjection *projection;
+  GeglNode       *source_node;
+  GeglNode       *parent_source_node;
+  GeglNode       *graph;
+  GeglNode       *offset_node;
+  GeglRectangle   bounding_box;
+  gint            suspend_resize;
+  gint            suspend_mask;
+  GeglBuffer     *suspended_mask_buffer;
+  GeglRectangle   suspended_mask_bounds;
+  gint            direct_update;
+  gint            transforming;
+  gboolean        expanded;
+  gboolean        pass_through;
+
+  /*  hackish temp states to make the projection/tiles stuff work  */
+  const Babl     *convert_format;
+  gboolean        reallocate_projection;
+};
+
+#define GET_PRIVATE(item) ((GimpGroupLayerPrivate *) gimp_group_layer_get_instance_private ((GimpGroupLayer *) (item)))
+
+
+static void            gimp_projectable_iface_init   (GimpProjectableInterface  *iface);
+static void            gimp_pickable_iface_init      (GimpPickableInterface     *iface);
+
+static void            gimp_group_layer_finalize     (GObject         *object);
+static void            gimp_group_layer_set_property (GObject         *object,
+                                                      guint            property_id,
+                                                      const GValue    *value,
+                                                      GParamSpec      *pspec);
+static void            gimp_group_layer_get_property (GObject         *object,
+                                                      guint            property_id,
+                                                      GValue          *value,
+                                                      GParamSpec      *pspec);
+
+static gint64          gimp_group_layer_get_memsize  (GimpObject      *object,
+                                                      gint64          *gui_size);
+
+static void        gimp_group_layer_ancestry_changed (GimpViewable    *viewable);
+static gboolean        gimp_group_layer_get_size     (GimpViewable    *viewable,
+                                                      gint            *width,
+                                                      gint            *height);
+static GimpContainer * gimp_group_layer_get_children (GimpViewable    *viewable);
+static gboolean        gimp_group_layer_get_expanded (GimpViewable    *viewable);
+static void            gimp_group_layer_set_expanded (GimpViewable    *viewable,
+                                                      gboolean         expanded);
+
+static gboolean  gimp_group_layer_is_position_locked (GimpItem        *item);
+static GimpItem      * gimp_group_layer_duplicate    (GimpItem        *item,
+                                                      GType            new_type);
+static void            gimp_group_layer_convert      (GimpItem        *item,
+                                                      GimpImage       *dest_image,
+                                                      GType            old_type);
+static void         gimp_group_layer_start_transform (GimpItem        *item,
+                                                      gboolean         push_undo);
+static void           gimp_group_layer_end_transform (GimpItem        *item,
+                                                      gboolean         push_undo);
+static void            gimp_group_layer_resize       (GimpItem        *item,
+                                                      GimpContext     *context,
+                                                      GimpFillType     fill_type,
+                                                      gint             new_width,
+                                                      gint             new_height,
+                                                      gint             offset_x,
+                                                      gint             offset_y);
+static GimpTransformResize
+                       gimp_group_layer_get_clip     (GimpItem        *item,
+                                                      GimpTransformResize clip_result);
+
+static gint64      gimp_group_layer_estimate_memsize (GimpDrawable      *drawable,
+                                                      GimpComponentType  component_type,
+                                                      gint               width,
+                                                      gint               height);
+static void            gimp_group_layer_update_all   (GimpDrawable      *drawable);
+
+static void            gimp_group_layer_translate    (GimpLayer       *layer,
+                                                      gint             offset_x,
+                                                      gint             offset_y);
+static void            gimp_group_layer_scale        (GimpLayer       *layer,
+                                                      gint             new_width,
+                                                      gint             new_height,
+                                                      gint             new_offset_x,
+                                                      gint             new_offset_y,
+                                                      GimpInterpolationType  interp_type,
+                                                      GimpProgress    *progress);
+static void            gimp_group_layer_flip         (GimpLayer       *layer,
+                                                      GimpContext     *context,
+                                                      GimpOrientationType flip_type,
+                                                      gdouble          axis,
+                                                      gboolean         clip_result);
+static void            gimp_group_layer_rotate       (GimpLayer       *layer,
+                                                      GimpContext     *context,
+                                                      GimpRotationType rotate_type,
+                                                      gdouble          center_x,
+                                                      gdouble          center_y,
+                                                      gboolean         clip_result);
+static void            gimp_group_layer_transform    (GimpLayer       *layer,
+                                                      GimpContext     *context,
+                                                      const GimpMatrix3 *matrix,
+                                                      GimpTransformDirection direction,
+                                                      GimpInterpolationType  interpolation_type,
+                                                      GimpTransformResize clip_result,
+                                                      GimpProgress      *progress);
+static void            gimp_group_layer_convert_type (GimpLayer         *layer,
+                                                      GimpImage         *dest_image,
+                                                      const Babl        *new_format,
+                                                      GimpColorProfile  *dest_profile,
+                                                      GeglDitherMethod   layer_dither_type,
+                                                      GeglDitherMethod   mask_dither_type,
+                                                      gboolean           push_undo,
+                                                      GimpProgress      *progress);
+static GeglNode   * gimp_group_layer_get_source_node (GimpDrawable      *drawable);
+
+static void         gimp_group_layer_opacity_changed (GimpLayer         *layer);
+static void  gimp_group_layer_effective_mode_changed (GimpLayer         *layer);
+static void
+          gimp_group_layer_excludes_backdrop_changed (GimpLayer         *layer);
+static GeglRectangle
+                   gimp_group_layer_get_bounding_box (GimpLayer         *layer);
+static void      gimp_group_layer_get_effective_mode (GimpLayer         *layer,
+                                                      GimpLayerMode          *mode,
+                                                      GimpLayerColorSpace    *blend_space,
+                                                      GimpLayerColorSpace    *composite_space,
+                                                      GimpLayerCompositeMode *composite_mode);
+static gboolean
+              gimp_group_layer_get_excludes_backdrop (GimpLayer         *layer);
+
+static const Babl    * gimp_group_layer_get_format   (GimpProjectable *projectable);
+static GeglRectangle
+       gimp_group_layer_projectable_get_bounding_box (GimpProjectable *projectable);
+static GeglNode      * gimp_group_layer_get_graph    (GimpProjectable *projectable);
+static void            gimp_group_layer_begin_render (GimpProjectable *projectable);
+static void            gimp_group_layer_end_render   (GimpProjectable *projectable);
+
+static void          gimp_group_layer_pickable_flush (GimpPickable    *pickable);
+static gdouble       gimp_group_layer_get_opacity_at (GimpPickable    *pickable,
+                                                      gint             x,
+                                                      gint             y);
+
+
+static void            gimp_group_layer_child_add    (GimpContainer   *container,
+                                                      GimpLayer       *child,
+                                                      GimpGroupLayer  *group);
+static void            gimp_group_layer_child_remove (GimpContainer   *container,
+                                                      GimpLayer       *child,
+                                                      GimpGroupLayer  *group);
+static void            gimp_group_layer_child_move   (GimpLayer       *child,
+                                                      GParamSpec      *pspec,
+                                                      GimpGroupLayer  *group);
+static void            gimp_group_layer_child_resize (GimpLayer       *child,
+                                                      GimpGroupLayer  *group);
+static void    gimp_group_layer_child_active_changed (GimpLayer       *child,
+                                                      GimpGroupLayer  *group);
+static void
+       gimp_group_layer_child_effective_mode_changed (GimpLayer       *child,
+                                                      GimpGroupLayer  *group);
+static void
+    gimp_group_layer_child_excludes_backdrop_changed (GimpLayer       *child,
+                                                      GimpGroupLayer  *group);
+
+static void            gimp_group_layer_flush        (GimpGroupLayer  *group);
+static void            gimp_group_layer_update       (GimpGroupLayer  *group);
+static void            gimp_group_layer_update_size  (GimpGroupLayer  *group);
+static void        gimp_group_layer_update_mask_size (GimpGroupLayer  *group);
+static void      gimp_group_layer_update_source_node (GimpGroupLayer  *group);
+static void        gimp_group_layer_update_mode_node (GimpGroupLayer  *group);
+
+static void            gimp_group_layer_stack_update (GimpDrawableStack *stack,
+                                                      gint               x,
+                                                      gint               y,
+                                                      gint               width,
+                                                      gint               height,
+                                                      GimpGroupLayer    *group);
+static void            gimp_group_layer_proj_update  (GimpProjection    *proj,
+                                                      gboolean           now,
+                                                      gint               x,
+                                                      gint               y,
+                                                      gint               width,
+                                                      gint               height,
+                                                      GimpGroupLayer    *group);
+
+
+G_DEFINE_TYPE_WITH_CODE (GimpGroupLayer, gimp_group_layer, GIMP_TYPE_LAYER,
+                         G_ADD_PRIVATE (GimpGroupLayer)
+                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_PROJECTABLE,
+                                                gimp_projectable_iface_init)
+                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_PICKABLE,
+                                                gimp_pickable_iface_init))
+
+
+#define parent_class gimp_group_layer_parent_class
+
+
+/* disable pass-through groups strength-reduction to normal groups.
+ * see gimp_group_layer_get_effective_mode().
+ */
+static gboolean no_pass_through_strength_reduction = FALSE;
+
+
+static void
+gimp_group_layer_class_init (GimpGroupLayerClass *klass)
+{
+  GObjectClass      *object_class      = G_OBJECT_CLASS (klass);
+  GimpObjectClass   *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+  GimpViewableClass *viewable_class    = GIMP_VIEWABLE_CLASS (klass);
+  GimpItemClass     *item_class        = GIMP_ITEM_CLASS (klass);
+  GimpDrawableClass *drawable_class    = GIMP_DRAWABLE_CLASS (klass);
+  GimpLayerClass    *layer_class       = GIMP_LAYER_CLASS (klass);
+
+  object_class->set_property             = gimp_group_layer_set_property;
+  object_class->get_property             = gimp_group_layer_get_property;
+  object_class->finalize                 = gimp_group_layer_finalize;
+
+  gimp_object_class->get_memsize         = gimp_group_layer_get_memsize;
+
+  viewable_class->default_icon_name      = "gimp-group-layer";
+  viewable_class->ancestry_changed       = gimp_group_layer_ancestry_changed;
+  viewable_class->get_size               = gimp_group_layer_get_size;
+  viewable_class->get_children           = gimp_group_layer_get_children;
+  viewable_class->set_expanded           = gimp_group_layer_set_expanded;
+  viewable_class->get_expanded           = gimp_group_layer_get_expanded;
+
+  item_class->is_position_locked         = gimp_group_layer_is_position_locked;
+  item_class->duplicate                  = gimp_group_layer_duplicate;
+  item_class->convert                    = gimp_group_layer_convert;
+  item_class->start_transform            = gimp_group_layer_start_transform;
+  item_class->end_transform              = gimp_group_layer_end_transform;
+  item_class->resize                     = gimp_group_layer_resize;
+  item_class->get_clip                   = gimp_group_layer_get_clip;
+
+  item_class->default_name               = _("Layer Group");
+  item_class->rename_desc                = C_("undo-type", "Rename Layer Group");
+  item_class->translate_desc             = C_("undo-type", "Move Layer Group");
+  item_class->scale_desc                 = C_("undo-type", "Scale Layer Group");
+  item_class->resize_desc                = C_("undo-type", "Resize Layer Group");
+  item_class->flip_desc                  = C_("undo-type", "Flip Layer Group");
+  item_class->rotate_desc                = C_("undo-type", "Rotate Layer Group");
+  item_class->transform_desc             = C_("undo-type", "Transform Layer Group");
+
+  drawable_class->estimate_memsize       = gimp_group_layer_estimate_memsize;
+  drawable_class->update_all             = gimp_group_layer_update_all;
+  drawable_class->get_source_node        = gimp_group_layer_get_source_node;
+
+  layer_class->opacity_changed           = gimp_group_layer_opacity_changed;
+  layer_class->effective_mode_changed    = gimp_group_layer_effective_mode_changed;
+  layer_class->excludes_backdrop_changed = gimp_group_layer_excludes_backdrop_changed;
+  layer_class->translate                 = gimp_group_layer_translate;
+  layer_class->scale                     = gimp_group_layer_scale;
+  layer_class->flip                      = gimp_group_layer_flip;
+  layer_class->rotate                    = gimp_group_layer_rotate;
+  layer_class->transform                 = gimp_group_layer_transform;
+  layer_class->convert_type              = gimp_group_layer_convert_type;
+  layer_class->get_bounding_box          = gimp_group_layer_get_bounding_box;
+  layer_class->get_effective_mode        = gimp_group_layer_get_effective_mode;
+  layer_class->get_excludes_backdrop     = gimp_group_layer_get_excludes_backdrop;
+
+  if (g_getenv ("GIMP_NO_PASS_THROUGH_STRENGTH_REDUCTION"))
+    no_pass_through_strength_reduction = TRUE;
+}
+
+static void
+gimp_projectable_iface_init (GimpProjectableInterface *iface)
+{
+  iface->get_image          = (GimpImage * (*) (GimpProjectable *)) gimp_item_get_image;
+  iface->get_format         = gimp_group_layer_get_format;
+  iface->get_offset         = (void (*) (GimpProjectable*, gint*, gint*)) gimp_item_get_offset;
+  iface->get_bounding_box   = gimp_group_layer_projectable_get_bounding_box;
+  iface->get_graph          = gimp_group_layer_get_graph;
+  iface->begin_render       = gimp_group_layer_begin_render;
+  iface->end_render         = gimp_group_layer_end_render;
+  iface->invalidate_preview = (void (*) (GimpProjectable*)) gimp_viewable_invalidate_preview;
+}
+
+static void
+gimp_pickable_iface_init (GimpPickableInterface *iface)
+{
+  iface->flush          = gimp_group_layer_pickable_flush;
+  iface->get_opacity_at = gimp_group_layer_get_opacity_at;
+}
+
+static void
+gimp_group_layer_init (GimpGroupLayer *group)
+{
+  GimpGroupLayerPrivate *private = GET_PRIVATE (group);
+
+  private->children = gimp_layer_stack_new (GIMP_TYPE_LAYER);
+  private->expanded = TRUE;
+
+  g_signal_connect (private->children, "add",
+                    G_CALLBACK (gimp_group_layer_child_add),
+                    group);
+  g_signal_connect (private->children, "remove",
+                    G_CALLBACK (gimp_group_layer_child_remove),
+                    group);
+
+  gimp_container_add_handler (private->children, "notify::offset-x",
+                              G_CALLBACK (gimp_group_layer_child_move),
+                              group);
+  gimp_container_add_handler (private->children, "notify::offset-y",
+                              G_CALLBACK (gimp_group_layer_child_move),
+                              group);
+  gimp_container_add_handler (private->children, "size-changed",
+                              G_CALLBACK (gimp_group_layer_child_resize),
+                              group);
+  gimp_container_add_handler (private->children, "bounding-box-changed",
+                              G_CALLBACK (gimp_group_layer_child_resize),
+                              group);
+  gimp_container_add_handler (private->children, "active-changed",
+                              G_CALLBACK (gimp_group_layer_child_active_changed),
+                              group);
+  gimp_container_add_handler (private->children, "effective-mode-changed",
+                              G_CALLBACK (gimp_group_layer_child_effective_mode_changed),
+                              group);
+  gimp_container_add_handler (private->children, "excludes-backdrop-changed",
+                              G_CALLBACK (gimp_group_layer_child_excludes_backdrop_changed),
+                              group);
+
+  g_signal_connect (private->children, "update",
+                    G_CALLBACK (gimp_group_layer_stack_update),
+                    group);
+
+  private->projection = gimp_projection_new (GIMP_PROJECTABLE (group));
+  gimp_projection_set_priority (private->projection, 1);
+
+  g_signal_connect (private->projection, "update",
+                    G_CALLBACK (gimp_group_layer_proj_update),
+                    group);
+}
+
+static void
+gimp_group_layer_finalize (GObject *object)
+{
+  GimpGroupLayerPrivate *private = GET_PRIVATE (object);
+
+  if (private->children)
+    {
+      g_signal_handlers_disconnect_by_func (private->children,
+                                            gimp_group_layer_child_add,
+                                            object);
+      g_signal_handlers_disconnect_by_func (private->children,
+                                            gimp_group_layer_child_remove,
+                                            object);
+      g_signal_handlers_disconnect_by_func (private->children,
+                                            gimp_group_layer_stack_update,
+                                            object);
+
+      /* this is particularly important to avoid reallocating the projection
+       * in response to a "bounding-box-changed" signal, which can be emitted
+       * during layer destruction.  see issue #4584.
+       */
+      gimp_container_remove_handlers_by_data (private->children, object);
+
+      g_clear_object (&private->children);
+    }
+
+  g_clear_object (&private->projection);
+  g_clear_object (&private->source_node);
+  g_clear_object (&private->graph);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gimp_group_layer_set_property (GObject      *object,
+                               guint         property_id,
+                               const GValue *value,
+                               GParamSpec   *pspec)
+{
+  switch (property_id)
+    {
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_group_layer_get_property (GObject    *object,
+                               guint       property_id,
+                               GValue     *value,
+                               GParamSpec *pspec)
+{
+  switch (property_id)
+    {
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static gint64
+gimp_group_layer_get_memsize (GimpObject *object,
+                              gint64     *gui_size)
+{
+  GimpGroupLayerPrivate *private = GET_PRIVATE (object);
+  gint64                 memsize = 0;
+
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (private->children), gui_size);
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (private->projection), gui_size);
+
+  return memsize + GIMP_OBJECT_CLASS (parent_class)->get_memsize (object,
+                                                                  gui_size);
+}
+
+static void
+gimp_group_layer_ancestry_changed (GimpViewable *viewable)
+{
+  GimpGroupLayerPrivate *private = GET_PRIVATE (viewable);
+
+  gimp_projection_set_priority (private->projection,
+                                gimp_viewable_get_depth (viewable) + 1);
+
+  GIMP_VIEWABLE_CLASS (parent_class)->ancestry_changed (viewable);
+}
+
+static gboolean
+gimp_group_layer_get_size (GimpViewable *viewable,
+                           gint         *width,
+                           gint         *height)
+{
+  GimpGroupLayerPrivate *private = GET_PRIVATE (viewable);
+
+  /*  return the size only if there are children ...  */
+  if (! gimp_container_is_empty (private->children))
+    {
+      return GIMP_VIEWABLE_CLASS (parent_class)->get_size (viewable,
+                                                           width, height);
+    }
+
+  /*  ... otherwise, return "no content"  */
+  return FALSE;
+}
+
+static GimpContainer *
+gimp_group_layer_get_children (GimpViewable *viewable)
+{
+  return GET_PRIVATE (viewable)->children;
+}
+
+static gboolean
+gimp_group_layer_get_expanded (GimpViewable *viewable)
+{
+  GimpGroupLayer *group = GIMP_GROUP_LAYER (viewable);
+
+  return GET_PRIVATE (group)->expanded;
+}
+
+static void
+gimp_group_layer_set_expanded (GimpViewable *viewable,
+                               gboolean      expanded)
+{
+  GimpGroupLayerPrivate *private = GET_PRIVATE (viewable);
+
+  if (private->expanded != expanded)
+    {
+      private->expanded = expanded;
+
+      gimp_viewable_expanded_changed (viewable);
+    }
+}
+
+static gboolean
+gimp_group_layer_is_position_locked (GimpItem *item)
+{
+  GimpGroupLayerPrivate *private = GET_PRIVATE (item);
+  GList                 *list;
+
+  for (list = gimp_item_stack_get_item_iter (GIMP_ITEM_STACK (private->children));
+       list;
+       list = g_list_next (list))
+    {
+      GimpItem *child = list->data;
+
+      if (gimp_item_is_position_locked (child))
+        return TRUE;
+    }
+
+  return GIMP_ITEM_CLASS (parent_class)->is_position_locked (item);
+}
+
+static GimpItem *
+gimp_group_layer_duplicate (GimpItem *item,
+                            GType     new_type)
+{
+  GimpItem *new_item;
+
+  g_return_val_if_fail (g_type_is_a (new_type, GIMP_TYPE_DRAWABLE), NULL);
+
+  new_item = GIMP_ITEM_CLASS (parent_class)->duplicate (item, new_type);
+
+  if (GIMP_IS_GROUP_LAYER (new_item))
+    {
+      GimpGroupLayerPrivate *private     = GET_PRIVATE (item);
+      GimpGroupLayer        *new_group   = GIMP_GROUP_LAYER (new_item);
+      GimpGroupLayerPrivate *new_private = GET_PRIVATE (new_item);
+      gint                   position    = 0;
+      GList                 *list;
+
+      gimp_group_layer_suspend_resize (new_group, FALSE);
+
+      for (list = gimp_item_stack_get_item_iter (GIMP_ITEM_STACK (private->children));
+           list;
+           list = g_list_next (list))
+        {
+          GimpItem      *child = list->data;
+          GimpItem      *new_child;
+          GimpLayerMask *mask;
+
+          new_child = gimp_item_duplicate (child, G_TYPE_FROM_INSTANCE (child));
+
+          gimp_object_set_name (GIMP_OBJECT (new_child),
+                                gimp_object_get_name (child));
+
+          mask = gimp_layer_get_mask (GIMP_LAYER (child));
+
+          if (mask)
+            {
+              GimpLayerMask *new_mask;
+
+              new_mask = gimp_layer_get_mask (GIMP_LAYER (new_child));
+
+              gimp_object_set_name (GIMP_OBJECT (new_mask),
+                                    gimp_object_get_name (mask));
+            }
+
+          gimp_viewable_set_parent (GIMP_VIEWABLE (new_child),
+                                    GIMP_VIEWABLE (new_group));
+
+          gimp_container_insert (new_private->children,
+                                 GIMP_OBJECT (new_child),
+                                 position++);
+        }
+
+      /*  force the projection to reallocate itself  */
+      GET_PRIVATE (new_group)->reallocate_projection = TRUE;
+
+      gimp_group_layer_resume_resize (new_group, FALSE);
+    }
+
+  return new_item;
+}
+
+static void
+gimp_group_layer_convert (GimpItem  *item,
+                          GimpImage *dest_image,
+                          GType      old_type)
+{
+  GimpGroupLayerPrivate *private = GET_PRIVATE (item);
+  GList                 *list;
+
+  for (list = gimp_item_stack_get_item_iter (GIMP_ITEM_STACK (private->children));
+       list;
+       list = g_list_next (list))
+    {
+      GimpItem *child = list->data;
+
+      GIMP_ITEM_GET_CLASS (child)->convert (child, dest_image,
+                                            G_TYPE_FROM_INSTANCE (child));
+    }
+
+  GIMP_ITEM_CLASS (parent_class)->convert (item, dest_image, old_type);
+}
+
+static void
+gimp_group_layer_start_transform (GimpItem *item,
+                             gboolean  push_undo)
+{
+  _gimp_group_layer_start_transform (GIMP_GROUP_LAYER (item), push_undo);
+
+  if (GIMP_ITEM_CLASS (parent_class)->start_transform)
+    GIMP_ITEM_CLASS (parent_class)->start_transform (item, push_undo);
+}
+
+static void
+gimp_group_layer_end_transform (GimpItem *item,
+                           gboolean  push_undo)
+{
+  if (GIMP_ITEM_CLASS (parent_class)->end_transform)
+    GIMP_ITEM_CLASS (parent_class)->end_transform (item, push_undo);
+
+  _gimp_group_layer_end_transform (GIMP_GROUP_LAYER (item), push_undo);
+}
+
+static void
+gimp_group_layer_resize (GimpItem     *item,
+                         GimpContext  *context,
+                         GimpFillType  fill_type,
+                         gint          new_width,
+                         gint          new_height,
+                         gint          offset_x,
+                         gint          offset_y)
+{
+  GimpGroupLayer        *group   = GIMP_GROUP_LAYER (item);
+  GimpGroupLayerPrivate *private = GET_PRIVATE (item);
+  GList                 *list;
+  gint                   x, y;
+
+  /* we implement GimpItem::resize(), instead of GimpLayer::resize(), so that
+   * GimpLayer doesn't resize the mask.  note that gimp_item_resize() calls
+   * gimp_item_{start,end}_move(), and not gimp_item_{start,end}_transform(),
+   * so that mask resizing is handled by gimp_group_layer_update_size().
+   */
+
+  x = gimp_item_get_offset_x (item) - offset_x;
+  y = gimp_item_get_offset_y (item) - offset_y;
+
+  gimp_group_layer_suspend_resize (group, TRUE);
+
+  list = gimp_item_stack_get_item_iter (GIMP_ITEM_STACK (private->children));
+
+  while (list)
+    {
+      GimpItem *child = list->data;
+      gint      child_width;
+      gint      child_height;
+      gint      child_x;
+      gint      child_y;
+
+      list = g_list_next (list);
+
+      if (gimp_rectangle_intersect (x,
+                                    y,
+                                    new_width,
+                                    new_height,
+                                    gimp_item_get_offset_x (child),
+                                    gimp_item_get_offset_y (child),
+                                    gimp_item_get_width  (child),
+                                    gimp_item_get_height (child),
+                                    &child_x,
+                                    &child_y,
+                                    &child_width,
+                                    &child_height))
+        {
+          gint child_offset_x = gimp_item_get_offset_x (child) - child_x;
+          gint child_offset_y = gimp_item_get_offset_y (child) - child_y;
+
+          gimp_item_resize (child, context, fill_type,
+                            child_width, child_height,
+                            child_offset_x, child_offset_y);
+        }
+      else if (gimp_item_is_attached (item))
+        {
+          gimp_image_remove_layer (gimp_item_get_image (item),
+                                   GIMP_LAYER (child),
+                                   TRUE, NULL);
+        }
+      else
+        {
+          gimp_container_remove (private->children, GIMP_OBJECT (child));
+        }
+    }
+
+  gimp_group_layer_resume_resize (group, TRUE);
+}
+
+static GimpTransformResize
+gimp_group_layer_get_clip (GimpItem            *item,
+                           GimpTransformResize  clip_result)
+{
+  /* TODO: add clipping support, by clipping all sublayers as a unit, instead
+   * of individually.
+   */
+  return GIMP_TRANSFORM_RESIZE_ADJUST;
+}
+
+static gint64
+gimp_group_layer_estimate_memsize (GimpDrawable      *drawable,
+                                   GimpComponentType  component_type,
+                                   gint               width,
+                                   gint               height)
+{
+  GimpGroupLayerPrivate *private = GET_PRIVATE (drawable);
+  GList                 *list;
+  GimpImageBaseType      base_type;
+  gint64                 memsize = 0;
+
+  for (list = gimp_item_stack_get_item_iter (GIMP_ITEM_STACK (private->children));
+       list;
+       list = g_list_next (list))
+    {
+      GimpDrawable *child = list->data;
+      gint          child_width;
+      gint          child_height;
+
+      child_width  = (gimp_item_get_width (GIMP_ITEM (child)) *
+                      width /
+                      gimp_item_get_width (GIMP_ITEM (drawable)));
+      child_height = (gimp_item_get_height (GIMP_ITEM (child)) *
+                      height /
+                      gimp_item_get_height (GIMP_ITEM (drawable)));
+
+      memsize += gimp_drawable_estimate_memsize (child,
+                                                 component_type,
+                                                 child_width,
+                                                 child_height);
+    }
+
+  base_type = gimp_drawable_get_base_type (drawable);
+
+  memsize += gimp_projection_estimate_memsize (base_type, component_type,
+                                               width, height);
+
+  return memsize +
+         GIMP_DRAWABLE_CLASS (parent_class)->estimate_memsize (drawable,
+                                                               component_type,
+                                                               width, height);
+}
+
+static void
+gimp_group_layer_update_all (GimpDrawable *drawable)
+{
+  GimpGroupLayerPrivate *private = GET_PRIVATE (drawable);
+  GList                 *list;
+
+  /*  redirect stack updates to the drawable, rather than to the projection  */
+  private->direct_update++;
+
+  for (list = gimp_item_stack_get_item_iter (GIMP_ITEM_STACK (private->children));
+       list;
+       list = g_list_next (list))
+    {
+      GimpFilter *child = list->data;
+
+      if (gimp_filter_get_active (child))
+        gimp_drawable_update_all (GIMP_DRAWABLE (child));
+    }
+
+  /*  redirect stack updates back to the projection  */
+  private->direct_update--;
+}
+
+static void
+gimp_group_layer_translate (GimpLayer *layer,
+                            gint       offset_x,
+                            gint       offset_y)
+{
+  GimpGroupLayer        *group   = GIMP_GROUP_LAYER (layer);
+  GimpGroupLayerPrivate *private = GET_PRIVATE (layer);
+  gint                   x, y;
+  GList                 *list;
+
+  /*  don't use gimp_group_layer_suspend_resize(), but rather increment
+   *  private->suspend_resize directly, since we're translating the group layer
+   *  here, rather than relying on gimp_group_layer_update_size() to do it.
+   */
+  private->suspend_resize++;
+
+  /*  redirect stack updates to the drawable, rather than to the projection  */
+  private->direct_update++;
+
+  /*  translate the child layers *before* updating the group's offset, so that,
+   *  if this is a nested group, the parent's bounds still reflect the original
+   *  layer positions.  This prevents the original area of the child layers,
+   *  which is updated as part of their translation, from being clipped to the
+   *  post-translation parent bounds (see issue #3484).  The new area of the
+   *  child layers, which is likewise updated as part of translation, *may* get
+   *  clipped to the old parent bounds, but the corresponding region will be
+   *  updated anyway when the parent is resized, once we update the group's
+   *  offset.
+   */
+  for (list = gimp_item_stack_get_item_iter (GIMP_ITEM_STACK (private->children));
+       list;
+       list = g_list_next (list))
+    {
+      GimpItem *child = list->data;
+
+      /*  don't push an undo here because undo will call us again  */
+      gimp_item_translate (child, offset_x, offset_y, FALSE);
+    }
+
+  gimp_item_get_offset (GIMP_ITEM (group), &x, &y);
+
+  x += offset_x;
+  y += offset_y;
+
+  /*  update the offset node  */
+  if (private->offset_node)
+    gegl_node_set (private->offset_node,
+                   "x", (gdouble) -x,
+                   "y", (gdouble) -y,
+                   NULL);
+
+  /*  invalidate the selection boundary because of a layer modification  */
+  gimp_drawable_invalidate_boundary (GIMP_DRAWABLE (layer));
+
+  /*  update the group layer offset  */
+  gimp_item_set_offset (GIMP_ITEM (group), x, y);
+
+  /*  redirect stack updates back to the projection  */
+  private->direct_update--;
+
+  /*  don't use gimp_group_layer_resume_resize(), but rather decrement
+   *  private->suspend_resize directly, so that gimp_group_layer_update_size()
+   *  isn't called.
+   */
+  private->suspend_resize--;
+}
+
+static void
+gimp_group_layer_scale (GimpLayer             *layer,
+                        gint                   new_width,
+                        gint                   new_height,
+                        gint                   new_offset_x,
+                        gint                   new_offset_y,
+                        GimpInterpolationType  interpolation_type,
+                        GimpProgress          *progress)
+{
+  GimpGroupLayer        *group   = GIMP_GROUP_LAYER (layer);
+  GimpGroupLayerPrivate *private = GET_PRIVATE (layer);
+  GimpItem              *item    = GIMP_ITEM (layer);
+  GimpObjectQueue       *queue   = NULL;
+  GList                 *list;
+  gdouble                width_factor;
+  gdouble                height_factor;
+  gint                   old_offset_x;
+  gint                   old_offset_y;
+
+  width_factor  = (gdouble) new_width  / (gdouble) gimp_item_get_width  (item);
+  height_factor = (gdouble) new_height / (gdouble) gimp_item_get_height (item);
+
+  old_offset_x = gimp_item_get_offset_x (item);
+  old_offset_y = gimp_item_get_offset_y (item);
+
+  if (progress)
+    {
+      queue    = gimp_object_queue_new (progress);
+      progress = GIMP_PROGRESS (queue);
+
+      gimp_object_queue_push_container (queue, private->children);
+    }
+
+  gimp_group_layer_suspend_resize (group, TRUE);
+
+  list = gimp_item_stack_get_item_iter (GIMP_ITEM_STACK (private->children));
+
+  while (list)
+    {
+      GimpItem *child = list->data;
+
+      list = g_list_next (list);
+
+      if (queue)
+        gimp_object_queue_pop (queue);
+
+      if (! gimp_item_scale_by_factors_with_origin (child,
+                                                    width_factor, height_factor,
+                                                    old_offset_x, old_offset_y,
+                                                    new_offset_x, new_offset_y,
+                                                    interpolation_type,
+                                                    progress))
+        {
+          /* new width or height are 0; remove item */
+          if (gimp_item_is_attached (item))
+            {
+              gimp_image_remove_layer (gimp_item_get_image (item),
+                                       GIMP_LAYER (child),
+                                       TRUE, NULL);
+            }
+          else
+            {
+              gimp_container_remove (private->children, GIMP_OBJECT (child));
+            }
+        }
+    }
+
+  gimp_group_layer_resume_resize (group, TRUE);
+
+  g_clear_object (&queue);
+}
+
+static void
+gimp_group_layer_flip (GimpLayer           *layer,
+                       GimpContext         *context,
+                       GimpOrientationType  flip_type,
+                       gdouble              axis,
+                       gboolean             clip_result)
+{
+  GimpGroupLayer        *group   = GIMP_GROUP_LAYER (layer);
+  GimpGroupLayerPrivate *private = GET_PRIVATE (layer);
+  GList                 *list;
+
+  gimp_group_layer_suspend_resize (group, TRUE);
+
+  for (list = gimp_item_stack_get_item_iter (GIMP_ITEM_STACK (private->children));
+       list;
+       list = g_list_next (list))
+    {
+      GimpItem *child = list->data;
+
+      gimp_item_flip (child, context,
+                      flip_type, axis, clip_result);
+    }
+
+  gimp_group_layer_resume_resize (group, TRUE);
+}
+
+static void
+gimp_group_layer_rotate (GimpLayer        *layer,
+                         GimpContext      *context,
+                         GimpRotationType  rotate_type,
+                         gdouble           center_x,
+                         gdouble           center_y,
+                         gboolean          clip_result)
+{
+  GimpGroupLayer        *group   = GIMP_GROUP_LAYER (layer);
+  GimpGroupLayerPrivate *private = GET_PRIVATE (layer);
+  GList                 *list;
+
+  gimp_group_layer_suspend_resize (group, TRUE);
+
+  for (list = gimp_item_stack_get_item_iter (GIMP_ITEM_STACK (private->children));
+       list;
+       list = g_list_next (list))
+    {
+      GimpItem *child = list->data;
+
+      gimp_item_rotate (child, context,
+                        rotate_type, center_x, center_y, clip_result);
+    }
+
+  gimp_group_layer_resume_resize (group, TRUE);
+}
+
+static void
+gimp_group_layer_transform (GimpLayer              *layer,
+                            GimpContext            *context,
+                            const GimpMatrix3      *matrix,
+                            GimpTransformDirection  direction,
+                            GimpInterpolationType   interpolation_type,
+                            GimpTransformResize     clip_result,
+                            GimpProgress           *progress)
+{
+  GimpGroupLayer        *group   = GIMP_GROUP_LAYER (layer);
+  GimpGroupLayerPrivate *private = GET_PRIVATE (layer);
+  GimpObjectQueue       *queue   = NULL;
+  GList                 *list;
+
+  if (progress)
+    {
+      queue    = gimp_object_queue_new (progress);
+      progress = GIMP_PROGRESS (queue);
+
+      gimp_object_queue_push_container (queue, private->children);
+    }
+
+  gimp_group_layer_suspend_resize (group, TRUE);
+
+  for (list = gimp_item_stack_get_item_iter (GIMP_ITEM_STACK (private->children));
+       list;
+       list = g_list_next (list))
+    {
+      GimpItem *child = list->data;
+
+      if (queue)
+        gimp_object_queue_pop (queue);
+
+      gimp_item_transform (child, context,
+                           matrix, direction,
+                           interpolation_type,
+                           clip_result, progress);
+    }
+
+  gimp_group_layer_resume_resize (group, TRUE);
+
+  g_clear_object (&queue);
+}
+
+static const Babl *
+get_projection_format (GimpProjectable   *projectable,
+                       GimpImageBaseType  base_type,
+                       GimpPrecision      precision)
+{
+  GimpImage *image = gimp_item_get_image (GIMP_ITEM (projectable));
+
+  switch (base_type)
+    {
+    case GIMP_RGB:
+    case GIMP_INDEXED:
+      return gimp_image_get_format (image, GIMP_RGB, precision, TRUE);
+
+    case GIMP_GRAY:
+      return gimp_image_get_format (image, GIMP_GRAY, precision, TRUE);
+    }
+
+  g_return_val_if_reached (NULL);
+}
+
+static void
+gimp_group_layer_convert_type (GimpLayer        *layer,
+                               GimpImage        *dest_image,
+                               const Babl       *new_format,
+                               GimpColorProfile *dest_profile,
+                               GeglDitherMethod  layer_dither_type,
+                               GeglDitherMethod  mask_dither_type,
+                               gboolean          push_undo,
+                               GimpProgress     *progress)
+{
+  GimpGroupLayer        *group   = GIMP_GROUP_LAYER (layer);
+  GimpGroupLayerPrivate *private = GET_PRIVATE (layer);
+  GeglBuffer            *buffer;
+
+  if (push_undo)
+    {
+      GimpImage *image = gimp_item_get_image (GIMP_ITEM (group));
+
+      gimp_image_undo_push_group_layer_convert (image, NULL, group);
+    }
+
+  /*  Need to temporarily set the projectable's format to the new
+   *  values so the projection will create its tiles with the right
+   *  depth
+   */
+  private->convert_format =
+    get_projection_format (GIMP_PROJECTABLE (group),
+                           gimp_babl_format_get_base_type (new_format),
+                           gimp_babl_format_get_precision (new_format));
+  gimp_projectable_structure_changed (GIMP_PROJECTABLE (group));
+  gimp_group_layer_flush (group);
+
+  buffer = gimp_pickable_get_buffer (GIMP_PICKABLE (private->projection));
+
+  gimp_drawable_set_buffer_full (GIMP_DRAWABLE (group),
+                                 FALSE, NULL,
+                                 buffer, NULL,
+                                 TRUE);
+
+  /*  reset, the actual format is right now  */
+  private->convert_format = NULL;
+}
+
+static GeglNode *
+gimp_group_layer_get_source_node (GimpDrawable *drawable)
+{
+  GimpGroupLayerPrivate *private = GET_PRIVATE (drawable);
+  GeglNode              *input;
+
+  g_warn_if_fail (private->source_node == NULL);
+
+  private->source_node = gegl_node_new ();
+
+  input = gegl_node_get_input_proxy (private->source_node, "input");
+
+  private->parent_source_node =
+    GIMP_DRAWABLE_CLASS (parent_class)->get_source_node (drawable);
+
+  gegl_node_add_child (private->source_node, private->parent_source_node);
+
+  g_object_unref (private->parent_source_node);
+
+  if (gegl_node_has_pad (private->parent_source_node, "input"))
+    {
+      gegl_node_connect_to (input,                       "output",
+                            private->parent_source_node, "input");
+    }
+
+  /* make sure we have a graph */
+  (void) gimp_group_layer_get_graph (GIMP_PROJECTABLE (drawable));
+
+  gegl_node_add_child (private->source_node, private->graph);
+
+  gimp_group_layer_update_source_node (GIMP_GROUP_LAYER (drawable));
+
+  return g_object_ref (private->source_node);
+}
+
+static void
+gimp_group_layer_opacity_changed (GimpLayer *layer)
+{
+  gimp_layer_update_effective_mode (layer);
+
+  if (GIMP_LAYER_CLASS (parent_class)->opacity_changed)
+    GIMP_LAYER_CLASS (parent_class)->opacity_changed (layer);
+}
+
+static void
+gimp_group_layer_effective_mode_changed (GimpLayer *layer)
+{
+  GimpGroupLayer        *group               = GIMP_GROUP_LAYER (layer);
+  GimpGroupLayerPrivate *private             = GET_PRIVATE (layer);
+  GimpLayerMode          mode;
+  gboolean               pass_through;
+  gboolean               update_bounding_box = FALSE;
+
+  gimp_layer_get_effective_mode (layer, &mode, NULL, NULL, NULL);
+
+  pass_through = (mode == GIMP_LAYER_MODE_PASS_THROUGH);
+
+  if (pass_through != private->pass_through)
+    {
+      if (private->pass_through && ! pass_through)
+        {
+          /* when switching from pass-through mode to a non-pass-through mode,
+           * flush the pickable in order to make sure the projection's buffer
+           * gets properly invalidated synchronously, so that it can be used
+           * as a source for the rest of the composition.
+           */
+          gimp_pickable_flush (GIMP_PICKABLE (private->projection));
+        }
+
+      private->pass_through = pass_through;
+
+      update_bounding_box = TRUE;
+    }
+
+  gimp_group_layer_update_source_node (group);
+  gimp_group_layer_update_mode_node (group);
+
+  if (update_bounding_box)
+    gimp_drawable_update_bounding_box (GIMP_DRAWABLE (group));
+
+  if (GIMP_LAYER_CLASS (parent_class)->effective_mode_changed)
+    GIMP_LAYER_CLASS (parent_class)->effective_mode_changed (layer);
+}
+
+static void
+gimp_group_layer_excludes_backdrop_changed (GimpLayer *layer)
+{
+  GimpGroupLayer *group = GIMP_GROUP_LAYER (layer);
+
+  gimp_group_layer_update_source_node (group);
+  gimp_group_layer_update_mode_node (group);
+
+  if (GIMP_LAYER_CLASS (parent_class)->excludes_backdrop_changed)
+    GIMP_LAYER_CLASS (parent_class)->excludes_backdrop_changed (layer);
+}
+
+static GeglRectangle
+gimp_group_layer_get_bounding_box (GimpLayer *layer)
+{
+  GimpGroupLayerPrivate *private = GET_PRIVATE (layer);
+
+  /* for pass-through groups, use the group's calculated bounding box, instead
+   * of the source-node's bounding box, since we don't update the bounding box
+   * on all events that may affect the latter, and since it includes the
+   * bounding box of the backdrop.  this means we can't attach filters that may
+   * affect the bounding box to a pass-through group (since their effect weon't
+   * be reflected by the group's bounding box), but attaching filters to pass-
+   * through groups makes little sense anyway.
+   */
+  if (private->pass_through)
+    return private->bounding_box;
+  else
+    return GIMP_LAYER_CLASS (parent_class)->get_bounding_box (layer);
+}
+
+static void
+gimp_group_layer_get_effective_mode (GimpLayer              *layer,
+                                     GimpLayerMode          *mode,
+                                     GimpLayerColorSpace    *blend_space,
+                                     GimpLayerColorSpace    *composite_space,
+                                     GimpLayerCompositeMode *composite_mode)
+{
+  GimpGroupLayerPrivate *private = GET_PRIVATE (layer);
+
+  /* try to strength-reduce pass-through groups to normal groups, which are
+   * cheaper.
+   */
+  if (gimp_layer_get_mode (layer) == GIMP_LAYER_MODE_PASS_THROUGH &&
+      ! no_pass_through_strength_reduction)
+    {
+      /* we perform the strength-reduction if:
+       *
+       *   - the group has no active children;
+       *
+       *   or,
+       *
+       *     - the group has a single active child; or,
+       *
+       *     - the effective mode of all the active children is normal, their
+       *       effective composite mode is UNION, and their effective blend and
+       *       composite spaces are equal;
+       *
+       *   - and,
+       *
+       *     - the group's opacity is 100%, and it has no mask (or the mask
+       *       isn't applied); or,
+       *
+       *     - the group's composite space equals the active children's
+       *       composite space.
+       */
+
+      GList    *list;
+      gboolean  reduce = TRUE;
+      gboolean  first  = TRUE;
+
+      *mode            = GIMP_LAYER_MODE_NORMAL;
+      *blend_space     = gimp_layer_get_real_blend_space (layer);
+      *composite_space = gimp_layer_get_real_composite_space (layer);
+      *composite_mode  = gimp_layer_get_real_composite_mode (layer);
+
+      for (list = gimp_item_stack_get_item_iter (GIMP_ITEM_STACK (private->children));
+           list;
+           list = g_list_next (list))
+        {
+          GimpLayer *child = list->data;
+
+          if (! gimp_filter_get_active (GIMP_FILTER (child)))
+            continue;
+
+          if (first)
+            {
+              gimp_layer_get_effective_mode (child,
+                                             mode,
+                                             blend_space,
+                                             composite_space,
+                                             composite_mode);
+
+              if (*mode == GIMP_LAYER_MODE_NORMAL_LEGACY)
+                *mode = GIMP_LAYER_MODE_NORMAL;
+
+              first = FALSE;
+            }
+          else
+            {
+              GimpLayerMode          other_mode;
+              GimpLayerColorSpace    other_blend_space;
+              GimpLayerColorSpace    other_composite_space;
+              GimpLayerCompositeMode other_composite_mode;
+
+              if (*mode           != GIMP_LAYER_MODE_NORMAL ||
+                  *composite_mode != GIMP_LAYER_COMPOSITE_UNION)
+                {
+                  reduce = FALSE;
+
+                  break;
+                }
+
+              gimp_layer_get_effective_mode (child,
+                                             &other_mode,
+                                             &other_blend_space,
+                                             &other_composite_space,
+                                             &other_composite_mode);
+
+              if (other_mode == GIMP_LAYER_MODE_NORMAL_LEGACY)
+                other_mode = GIMP_LAYER_MODE_NORMAL;
+
+              if (other_mode            != *mode            ||
+                  other_blend_space     != *blend_space     ||
+                  other_composite_space != *composite_space ||
+                  other_composite_mode  != *composite_mode)
+                {
+                  reduce = FALSE;
+
+                  break;
+                }
+            }
+        }
+
+      if (reduce)
+        {
+          gboolean has_mask;
+
+          has_mask = gimp_layer_get_mask (layer) &&
+                     gimp_layer_get_apply_mask (layer);
+
+          if (first                                                  ||
+              (gimp_layer_get_opacity (layer) == GIMP_OPACITY_OPAQUE &&
+               ! has_mask)                                           ||
+              *composite_space == gimp_layer_get_real_composite_space (layer))
+            {
+              /* strength reduction succeeded! */
+              return;
+            }
+        }
+    }
+
+  /* strength-reduction failed.  chain up. */
+  GIMP_LAYER_CLASS (parent_class)->get_effective_mode (layer,
+                                                       mode,
+                                                       blend_space,
+                                                       composite_space,
+                                                       composite_mode);
+}
+
+static gboolean
+gimp_group_layer_get_excludes_backdrop (GimpLayer *layer)
+{
+  GimpGroupLayerPrivate *private = GET_PRIVATE (layer);
+
+  if (private->pass_through)
+    {
+      GList *list;
+
+      for (list = gimp_item_stack_get_item_iter (GIMP_ITEM_STACK (private->children));
+           list;
+           list = g_list_next (list))
+        {
+          GimpFilter *child = list->data;
+
+          if (gimp_filter_get_active (child) &&
+              gimp_layer_get_excludes_backdrop (GIMP_LAYER (child)))
+            return TRUE;
+        }
+
+      return FALSE;
+    }
+  else
+    return GIMP_LAYER_CLASS (parent_class)->get_excludes_backdrop (layer);
+}
+
+static const Babl *
+gimp_group_layer_get_format (GimpProjectable *projectable)
+{
+  GimpGroupLayerPrivate *private = GET_PRIVATE (projectable);
+  GimpImageBaseType      base_type;
+  GimpPrecision          precision;
+
+  if (private->convert_format)
+    return private->convert_format;
+
+  base_type = gimp_drawable_get_base_type (GIMP_DRAWABLE (projectable));
+  precision = gimp_drawable_get_precision (GIMP_DRAWABLE (projectable));
+
+  return get_projection_format (projectable, base_type, precision);
+}
+
+static GeglRectangle
+gimp_group_layer_projectable_get_bounding_box (GimpProjectable *projectable)
+{
+  GimpGroupLayerPrivate *private = GET_PRIVATE (projectable);
+
+  return private->bounding_box;
+}
+
+static GeglNode *
+gimp_group_layer_get_graph (GimpProjectable *projectable)
+{
+  GimpGroupLayer        *group   = GIMP_GROUP_LAYER (projectable);
+  GimpGroupLayerPrivate *private = GET_PRIVATE (projectable);
+  GeglNode              *input;
+  GeglNode              *layers_node;
+  GeglNode              *output;
+  gint                   off_x;
+  gint                   off_y;
+
+  if (private->graph)
+    return private->graph;
+
+  private->graph = gegl_node_new ();
+
+  input = gegl_node_get_input_proxy (private->graph, "input");
+
+  layers_node =
+    gimp_filter_stack_get_graph (GIMP_FILTER_STACK (private->children));
+
+  gegl_node_add_child (private->graph, layers_node);
+
+  gegl_node_connect_to (input,       "output",
+                        layers_node, "input");
+
+  gimp_item_get_offset (GIMP_ITEM (group), &off_x, &off_y);
+
+  private->offset_node = gegl_node_new_child (private->graph,
+                                              "operation", "gegl:translate",
+                                              "x",         (gdouble) -off_x,
+                                              "y",         (gdouble) -off_y,
+                                              NULL);
+
+  gegl_node_connect_to (layers_node,          "output",
+                        private->offset_node, "input");
+
+  output = gegl_node_get_output_proxy (private->graph, "output");
+
+  gegl_node_connect_to (private->offset_node, "output",
+                        output,               "input");
+
+  return private->graph;
+}
+
+static void
+gimp_group_layer_begin_render (GimpProjectable *projectable)
+{
+  GimpGroupLayerPrivate *private = GET_PRIVATE (projectable);
+
+  if (private->source_node == NULL)
+    return;
+
+  if (private->pass_through)
+    gegl_node_disconnect (private->graph, "input");
+}
+
+static void
+gimp_group_layer_end_render (GimpProjectable *projectable)
+{
+  GimpGroupLayerPrivate *private = GET_PRIVATE (projectable);
+
+  if (private->source_node == NULL)
+    return;
+
+  if (private->pass_through)
+    {
+      GeglNode *input;
+
+      input = gegl_node_get_input_proxy (private->source_node, "input");
+
+      gegl_node_connect_to (input,          "output",
+                            private->graph, "input");
+    }
+}
+
+static void
+gimp_group_layer_pickable_flush (GimpPickable *pickable)
+{
+  GimpGroupLayerPrivate *private = GET_PRIVATE (pickable);
+
+  gimp_pickable_flush (GIMP_PICKABLE (private->projection));
+}
+
+static gdouble
+gimp_group_layer_get_opacity_at (GimpPickable *pickable,
+                                 gint          x,
+                                 gint          y)
+{
+  /* Only consider child layers as having content */
+
+  return GIMP_OPACITY_TRANSPARENT;
+}
+
+
+/*  public functions  */
+
+GimpLayer *
+gimp_group_layer_new (GimpImage *image)
+{
+  GimpGroupLayer *group;
+  const Babl     *format;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  format = gimp_image_get_layer_format (image, TRUE);
+
+  group = GIMP_GROUP_LAYER (gimp_drawable_new (GIMP_TYPE_GROUP_LAYER,
+                                               image, NULL,
+                                               0, 0, 1, 1,
+                                               format));
+
+  gimp_layer_set_mode (GIMP_LAYER (group),
+                       gimp_image_get_default_new_layer_mode (image),
+                       FALSE);
+
+  return GIMP_LAYER (group);
+}
+
+GimpProjection *
+gimp_group_layer_get_projection (GimpGroupLayer *group)
+{
+  g_return_val_if_fail (GIMP_IS_GROUP_LAYER (group), NULL);
+
+  return GET_PRIVATE (group)->projection;
+}
+
+void
+gimp_group_layer_suspend_resize (GimpGroupLayer *group,
+                                 gboolean        push_undo)
+{
+  GimpItem *item;
+
+  g_return_if_fail (GIMP_IS_GROUP_LAYER (group));
+
+  item = GIMP_ITEM (group);
+
+  if (! gimp_item_is_attached (item))
+    push_undo = FALSE;
+
+  if (push_undo)
+    gimp_image_undo_push_group_layer_suspend_resize (gimp_item_get_image (item),
+                                                     NULL, group);
+
+  GET_PRIVATE (group)->suspend_resize++;
+}
+
+void
+gimp_group_layer_resume_resize (GimpGroupLayer *group,
+                                gboolean        push_undo)
+{
+  GimpGroupLayerPrivate *private;
+  GimpItem              *item;
+  GimpItem              *mask = NULL;
+  GeglBuffer            *mask_buffer;
+  GeglRectangle          mask_bounds;
+  GimpUndo              *undo;
+
+  g_return_if_fail (GIMP_IS_GROUP_LAYER (group));
+
+  private = GET_PRIVATE (group);
+
+  g_return_if_fail (private->suspend_resize > 0);
+
+  item = GIMP_ITEM (group);
+
+  if (! gimp_item_is_attached (item))
+    push_undo = FALSE;
+
+  if (push_undo)
+    {
+      undo =
+        gimp_image_undo_push_group_layer_resume_resize (gimp_item_get_image (item),
+                                                        NULL, group);
+
+      /* if there were any {suspend,resume}_mask() calls during the time the
+       * group's size was suspended, the resume_mask() calls will not have seen
+       * any changes to the mask, and will therefore won't restore the mask
+       * during undo.  if the group's bounding box did change while resize was
+       * suspended, and if there are no other {suspend,resume}_mask() blocks
+       * that will see the resized mask, we have to restore the mask during the
+       * resume_resize() undo.
+       *
+       * we ref the mask buffer here, and compare it to the mask buffer after
+       * updating the size.
+       */
+      if (private->suspend_resize == 1 && private->suspend_mask == 0)
+        {
+          mask = GIMP_ITEM (gimp_layer_get_mask (GIMP_LAYER (group)));
+
+          if (mask)
+            {
+              mask_buffer =
+                g_object_ref (gimp_drawable_get_buffer (GIMP_DRAWABLE (mask)));
+
+              mask_bounds.x      = gimp_item_get_offset_x (mask);
+              mask_bounds.y      = gimp_item_get_offset_y (mask);
+              mask_bounds.width  = gimp_item_get_width    (mask);
+              mask_bounds.height = gimp_item_get_height   (mask);
+            }
+        }
+    }
+
+  private->suspend_resize--;
+
+  if (private->suspend_resize == 0)
+    {
+      gimp_group_layer_update_size (group);
+
+      if (mask)
+        {
+          /* if the mask changed, make sure it's restored during undo, as per
+           * the comment above.
+           */
+          if (gimp_drawable_get_buffer (GIMP_DRAWABLE (mask)) != mask_buffer)
+            {
+              g_return_if_fail (undo != NULL);
+
+              GIMP_GROUP_LAYER_UNDO (undo)->mask_buffer = mask_buffer;
+              GIMP_GROUP_LAYER_UNDO (undo)->mask_bounds = mask_bounds;
+            }
+          else
+            {
+              g_object_unref (mask_buffer);
+            }
+        }
+    }
+}
+
+void
+gimp_group_layer_suspend_mask (GimpGroupLayer *group,
+                               gboolean        push_undo)
+{
+  GimpGroupLayerPrivate *private;
+  GimpItem              *item;
+
+  g_return_if_fail (GIMP_IS_GROUP_LAYER (group));
+
+  private = GET_PRIVATE (group);
+  item    = GIMP_ITEM (group);
+
+  /* avoid pushing an undo step if this is a nested suspend_mask() call, since
+   * the value of 'push_undo' in nested calls should be the same as that passed
+   * to the outermost call, and only pushing an undo step for the outermost
+   * call in this case is enough.  we can't support cases where the values of
+   * 'push_undo' in nested calls are different in a meaningful way, and
+   * avoiding undo steps for nested calls prevents us from storing multiple
+   * references to the suspend mask buffer on the undo stack.  while storing
+   * multiple references to the buffer doesn't waste any memory (since all the
+   * references are to the same buffer), it does cause the undo stack memory-
+   * usage estimation to overshoot, potentially resulting in undo steps being
+   * dropped unnecessarily.
+   */
+  if (! gimp_item_is_attached (item) || private->suspend_mask > 0)
+    push_undo = FALSE;
+
+  if (push_undo)
+    gimp_image_undo_push_group_layer_suspend_mask (gimp_item_get_image (item),
+                                                   NULL, group);
+
+  if (private->suspend_mask == 0)
+    {
+      if (gimp_layer_get_mask (GIMP_LAYER (group)))
+        {
+          GimpItem *mask = GIMP_ITEM (gimp_layer_get_mask (GIMP_LAYER (group)));
+
+          private->suspended_mask_buffer =
+            g_object_ref (gimp_drawable_get_buffer (GIMP_DRAWABLE (mask)));
+
+          private->suspended_mask_bounds.x      = gimp_item_get_offset_x (mask);
+          private->suspended_mask_bounds.y      = gimp_item_get_offset_y (mask);
+          private->suspended_mask_bounds.width  = gimp_item_get_width    (mask);
+          private->suspended_mask_bounds.height = gimp_item_get_height   (mask);
+        }
+      else
+        {
+          private->suspended_mask_buffer = NULL;
+        }
+    }
+
+  private->suspend_mask++;
+}
+
+void
+gimp_group_layer_resume_mask (GimpGroupLayer *group,
+                              gboolean        push_undo)
+{
+  GimpGroupLayerPrivate *private;
+  GimpItem              *item;
+
+  g_return_if_fail (GIMP_IS_GROUP_LAYER (group));
+
+  private = GET_PRIVATE (group);
+
+  g_return_if_fail (private->suspend_mask > 0);
+
+  item = GIMP_ITEM (group);
+
+  /* avoid pushing an undo step if this is a nested resume_mask() call.  see
+   * the comment in gimp_group_layer_suspend_mask().
+   */
+  if (! gimp_item_is_attached (item) || private->suspend_mask > 1)
+    push_undo = FALSE;
+
+  if (push_undo)
+    gimp_image_undo_push_group_layer_resume_mask (gimp_item_get_image (item),
+                                                  NULL, group);
+
+  private->suspend_mask--;
+
+  if (private->suspend_mask == 0)
+    g_clear_object (&private->suspended_mask_buffer);
+}
+
+
+/*  protected functions  */
+
+void
+_gimp_group_layer_set_suspended_mask (GimpGroupLayer      *group,
+                                      GeglBuffer          *buffer,
+                                      const GeglRectangle *bounds)
+{
+  GimpGroupLayerPrivate *private;
+
+  g_return_if_fail (GIMP_IS_GROUP_LAYER (group));
+  g_return_if_fail (buffer != NULL);
+  g_return_if_fail (bounds != NULL);
+
+  private = GET_PRIVATE (group);
+
+  g_return_if_fail (private->suspend_mask > 0);
+
+  g_object_ref (buffer);
+
+  g_clear_object (&private->suspended_mask_buffer);
+
+  private->suspended_mask_buffer = buffer;
+  private->suspended_mask_bounds = *bounds;
+}
+
+GeglBuffer *
+_gimp_group_layer_get_suspended_mask (GimpGroupLayer *group,
+                                      GeglRectangle  *bounds)
+{
+  GimpGroupLayerPrivate *private;
+  GimpLayerMask         *mask;
+
+  g_return_val_if_fail (GIMP_IS_GROUP_LAYER (group), NULL);
+  g_return_val_if_fail (bounds != NULL, NULL);
+
+  private = GET_PRIVATE (group);
+  mask    = gimp_layer_get_mask (GIMP_LAYER (group));
+
+  g_return_val_if_fail (private->suspend_mask > 0, NULL);
+
+  if (mask &&
+      gimp_drawable_get_buffer (GIMP_DRAWABLE (mask)) !=
+      private->suspended_mask_buffer)
+    {
+      *bounds = private->suspended_mask_bounds;
+
+      return private->suspended_mask_buffer;
+    }
+
+  return NULL;
+}
+
+void
+_gimp_group_layer_start_transform (GimpGroupLayer *group,
+                                   gboolean        push_undo)
+{
+  GimpGroupLayerPrivate *private;
+  GimpItem              *item;
+
+  g_return_if_fail (GIMP_IS_GROUP_LAYER (group));
+
+  private = GET_PRIVATE (group);
+  item    = GIMP_ITEM (group);
+
+  g_return_if_fail (private->suspend_mask == 0);
+
+  if (! gimp_item_is_attached (item))
+    push_undo = FALSE;
+
+  if (push_undo)
+    gimp_image_undo_push_group_layer_start_transform (gimp_item_get_image (item),
+                                                      NULL, group);
+
+  private->transforming++;
+}
+
+void
+_gimp_group_layer_end_transform (GimpGroupLayer *group,
+                                 gboolean        push_undo)
+{
+  GimpGroupLayerPrivate *private;
+  GimpItem              *item;
+
+  g_return_if_fail (GIMP_IS_GROUP_LAYER (group));
+
+  private = GET_PRIVATE (group);
+  item    = GIMP_ITEM (group);
+
+  g_return_if_fail (private->suspend_mask == 0);
+  g_return_if_fail (private->transforming > 0);
+
+  if (! gimp_item_is_attached (item))
+    push_undo = FALSE;
+
+  if (push_undo)
+    gimp_image_undo_push_group_layer_end_transform (gimp_item_get_image (item),
+                                                    NULL, group);
+
+  private->transforming--;
+
+  if (private->transforming == 0)
+    gimp_group_layer_update_mask_size (GIMP_GROUP_LAYER (item));
+}
+
+
+/*  private functions  */
+
+static void
+gimp_group_layer_child_add (GimpContainer  *container,
+                            GimpLayer      *child,
+                            GimpGroupLayer *group)
+{
+  gimp_group_layer_update (group);
+
+  if (gimp_filter_get_active (GIMP_FILTER (child)))
+    {
+      gimp_layer_update_effective_mode (GIMP_LAYER (group));
+
+      if (gimp_layer_get_excludes_backdrop (child))
+        gimp_layer_update_excludes_backdrop (GIMP_LAYER (group));
+    }
+}
+
+static void
+gimp_group_layer_child_remove (GimpContainer  *container,
+                               GimpLayer      *child,
+                               GimpGroupLayer *group)
+{
+  gimp_group_layer_update (group);
+
+  if (gimp_filter_get_active (GIMP_FILTER (child)))
+    {
+      gimp_layer_update_effective_mode (GIMP_LAYER (group));
+
+      if (gimp_layer_get_excludes_backdrop (child))
+        gimp_layer_update_excludes_backdrop (GIMP_LAYER (group));
+    }
+}
+
+static void
+gimp_group_layer_child_move (GimpLayer      *child,
+                             GParamSpec     *pspec,
+                             GimpGroupLayer *group)
+{
+  gimp_group_layer_update (group);
+}
+
+static void
+gimp_group_layer_child_resize (GimpLayer      *child,
+                               GimpGroupLayer *group)
+{
+  gimp_group_layer_update (group);
+}
+
+static void
+gimp_group_layer_child_active_changed (GimpLayer      *child,
+                                       GimpGroupLayer *group)
+{
+  gimp_layer_update_effective_mode (GIMP_LAYER (group));
+
+  if (gimp_layer_get_excludes_backdrop (child))
+    gimp_layer_update_excludes_backdrop (GIMP_LAYER (group));
+}
+
+static void
+gimp_group_layer_child_effective_mode_changed (GimpLayer      *child,
+                                               GimpGroupLayer *group)
+{
+  if (gimp_filter_get_active (GIMP_FILTER (child)))
+    gimp_layer_update_effective_mode (GIMP_LAYER (group));
+}
+
+static void
+gimp_group_layer_child_excludes_backdrop_changed (GimpLayer      *child,
+                                                  GimpGroupLayer *group)
+{
+  if (gimp_filter_get_active (GIMP_FILTER (child)))
+    gimp_layer_update_excludes_backdrop (GIMP_LAYER (group));
+}
+
+static void
+gimp_group_layer_flush (GimpGroupLayer *group)
+{
+  GimpGroupLayerPrivate *private = GET_PRIVATE (group);
+
+  if (private->pass_through)
+    {
+      /*  flush the projectable, not the pickable, because the source
+       *  node of pass-through groups doesn't use the projection's
+       *  buffer, hence there's no need to invalidate it synchronously.
+       */
+      gimp_projectable_flush (GIMP_PROJECTABLE (group), TRUE);
+    }
+  else
+    {
+      /* make sure we have a buffer, and stop any idle rendering, which is
+       * initiated when a new buffer is allocated.  the call to
+       * gimp_pickable_flush() below causes any pending idle rendering to
+       * finish synchronously, so this needs to happen before.
+       */
+      gimp_pickable_get_buffer (GIMP_PICKABLE (private->projection));
+      gimp_projection_stop_rendering (private->projection);
+
+      /*  flush the pickable not the projectable because flushing the
+       *  pickable will finish all invalidation on the projection so it
+       *  can be used as source (note that it will still be constructed
+       *  when the actual read happens, so this it not a performance
+       *  problem)
+       */
+      gimp_pickable_flush (GIMP_PICKABLE (private->projection));
+    }
+}
+
+static void
+gimp_group_layer_update (GimpGroupLayer *group)
+{
+  if (GET_PRIVATE (group)->suspend_resize == 0)
+    {
+      gimp_group_layer_update_size (group);
+    }
+}
+
+static void
+gimp_group_layer_update_size (GimpGroupLayer *group)
+{
+  GimpGroupLayerPrivate *private = GET_PRIVATE (group);
+  GimpItem              *item    = GIMP_ITEM (group);
+  GimpLayer             *layer   = GIMP_LAYER (group);
+  GimpItem              *mask    = GIMP_ITEM (gimp_layer_get_mask (layer));
+  GeglRectangle          old_bounds;
+  GeglRectangle          bounds;
+  GeglRectangle          old_bounding_box;
+  GeglRectangle          bounding_box;
+  gboolean               first   = TRUE;
+  gboolean               size_changed;
+  gboolean               resize_mask;
+  GList                 *list;
+
+  old_bounds.x      = gimp_item_get_offset_x (item);
+  old_bounds.y      = gimp_item_get_offset_y (item);
+  old_bounds.width  = gimp_item_get_width    (item);
+  old_bounds.height = gimp_item_get_height   (item);
+
+  bounds.x          = 0;
+  bounds.y          = 0;
+  bounds.width      = 1;
+  bounds.height     = 1;
+
+  old_bounding_box  = private->bounding_box;
+  bounding_box      = bounds;
+
+  for (list = gimp_item_stack_get_item_iter (GIMP_ITEM_STACK (private->children));
+       list;
+       list = g_list_next (list))
+    {
+      GimpItem      *child = list->data;
+      GeglRectangle  child_bounds;
+      GeglRectangle  child_bounding_box;
+
+      if (! gimp_viewable_get_size (GIMP_VIEWABLE (child),
+                                    &child_bounds.width, &child_bounds.height))
+        {
+          /*  ignore children without content (empty group layers);
+           *  see bug 777017
+           */
+          continue;
+        }
+
+      gimp_item_get_offset (child, &child_bounds.x, &child_bounds.y);
+
+      child_bounding_box =
+        gimp_drawable_get_bounding_box (GIMP_DRAWABLE (child));
+
+      child_bounding_box.x += child_bounds.x;
+      child_bounding_box.y += child_bounds.y;
+
+      if (first)
+        {
+          bounds       = child_bounds;
+          bounding_box = child_bounding_box;
+
+          first = FALSE;
+        }
+      else
+        {
+          gegl_rectangle_bounding_box (&bounds,
+                                       &bounds, &child_bounds);
+          gegl_rectangle_bounding_box (&bounding_box,
+                                       &bounding_box, &child_bounding_box);
+        }
+    }
+
+  bounding_box.x -= bounds.x;
+  bounding_box.y -= bounds.y;
+
+  size_changed = ! (gegl_rectangle_equal (&bounds,       &old_bounds) &&
+                    gegl_rectangle_equal (&bounding_box, &old_bounding_box));
+
+  resize_mask = mask && ! gegl_rectangle_equal (&bounds, &old_bounds);
+
+  /* if we show the mask, invalidate the old mask area */
+  if (resize_mask && gimp_layer_get_show_mask (layer))
+    {
+      gimp_drawable_update (GIMP_DRAWABLE (group),
+                            gimp_item_get_offset_x (mask) - old_bounds.x,
+                            gimp_item_get_offset_y (mask) - old_bounds.y,
+                            gimp_item_get_width    (mask),
+                            gimp_item_get_height   (mask));
+    }
+
+  if (private->reallocate_projection || size_changed)
+    {
+      GeglBuffer *buffer;
+
+      /* if the graph is already constructed, set the offset node's
+       * coordinates first, so the graph is in the right state when
+       * the projection is reallocated, see bug #730550.
+       */
+      if (private->offset_node)
+        gegl_node_set (private->offset_node,
+                       "x", (gdouble) -bounds.x,
+                       "y", (gdouble) -bounds.y,
+                       NULL);
+
+      /* update our offset *before* calling gimp_pickable_get_buffer(), so
+       * that if our graph isn't constructed yet, the offset node picks
+       * up the right coordinates in gimp_group_layer_get_graph().
+       */
+      gimp_item_set_offset (item, bounds.x, bounds.y);
+
+      /* update the bounding box before updating the projection, so that it
+       * picks up the right size.
+       */
+      private->bounding_box = bounding_box;
+
+      if (private->reallocate_projection)
+        {
+          private->reallocate_projection = FALSE;
+
+          gimp_projectable_structure_changed (GIMP_PROJECTABLE (group));
+        }
+      else
+        {
+          /* when there's no need to reallocate the projection, we call
+           * gimp_projectable_bounds_changed(), rather than structure_chaned(),
+           * so that the projection simply copies the old content over to the
+           * new buffer with an offset, rather than re-renders the graph.
+           */
+          gimp_projectable_bounds_changed (GIMP_PROJECTABLE (group),
+                                           old_bounds.x, old_bounds.y);
+        }
+
+      buffer = gimp_pickable_get_buffer (GIMP_PICKABLE (private->projection));
+
+      gimp_drawable_set_buffer_full (GIMP_DRAWABLE (group),
+                                     FALSE, NULL,
+                                     buffer, &bounds,
+                                     FALSE /* don't update the drawable, the
+                                            * flush() below will take care of
+                                            * that.
+                                            */);
+
+      gimp_group_layer_flush (group);
+    }
+
+  /* resize the mask if not transforming (in which case, GimpLayer takes care
+   * of the mask)
+   */
+  if (resize_mask && ! private->transforming)
+    gimp_group_layer_update_mask_size (group);
+
+  /* if we show the mask, invalidate the new mask area */
+  if (resize_mask && gimp_layer_get_show_mask (layer))
+    {
+      gimp_drawable_update (GIMP_DRAWABLE (group),
+                            gimp_item_get_offset_x (mask) - bounds.x,
+                            gimp_item_get_offset_y (mask) - bounds.y,
+                            gimp_item_get_width    (mask),
+                            gimp_item_get_height   (mask));
+    }
+}
+
+static void
+gimp_group_layer_update_mask_size (GimpGroupLayer *group)
+{
+  GimpGroupLayerPrivate *private = GET_PRIVATE (group);
+  GimpItem              *item    = GIMP_ITEM (group);
+  GimpItem              *mask;
+  GeglBuffer            *buffer;
+  GeglBuffer            *mask_buffer;
+  GeglRectangle          bounds;
+  GeglRectangle          mask_bounds;
+  GeglRectangle          copy_bounds;
+  gboolean               intersect;
+
+  mask = GIMP_ITEM (gimp_layer_get_mask (GIMP_LAYER (group)));
+
+  if (! mask)
+    return;
+
+  bounds.x           = gimp_item_get_offset_x (item);
+  bounds.y           = gimp_item_get_offset_y (item);
+  bounds.width       = gimp_item_get_width    (item);
+  bounds.height      = gimp_item_get_height   (item);
+
+  mask_bounds.x      = gimp_item_get_offset_x (mask);
+  mask_bounds.y      = gimp_item_get_offset_y (mask);
+  mask_bounds.width  = gimp_item_get_width    (mask);
+  mask_bounds.height = gimp_item_get_height   (mask);
+
+  if (gegl_rectangle_equal (&bounds, &mask_bounds))
+    return;
+
+  buffer = gegl_buffer_new (GEGL_RECTANGLE (0, 0, bounds.width, bounds.height),
+                            gimp_drawable_get_format (GIMP_DRAWABLE (mask)));
+
+  if (private->suspended_mask_buffer)
+    {
+      /* copy the suspended mask into the new mask */
+      mask_buffer = private->suspended_mask_buffer;
+      mask_bounds = private->suspended_mask_bounds;
+    }
+  else
+    {
+      /* copy the old mask into the new mask */
+      mask_buffer = gimp_drawable_get_buffer (GIMP_DRAWABLE (mask));
+    }
+
+  intersect = gimp_rectangle_intersect (bounds.x,
+                                        bounds.y,
+                                        bounds.width,
+                                        bounds.height,
+                                        mask_bounds.x,
+                                        mask_bounds.y,
+                                        mask_bounds.width,
+                                        mask_bounds.height,
+                                        &copy_bounds.x,
+                                        &copy_bounds.y,
+                                        &copy_bounds.width,
+                                        &copy_bounds.height);
+
+  if (intersect)
+    {
+      gimp_gegl_buffer_copy (mask_buffer,
+                             GEGL_RECTANGLE (copy_bounds.x - mask_bounds.x,
+                                             copy_bounds.y - mask_bounds.y,
+                                             copy_bounds.width,
+                                             copy_bounds.height),
+                             GEGL_ABYSS_NONE,
+                             buffer,
+                             GEGL_RECTANGLE (copy_bounds.x - bounds.x,
+                                             copy_bounds.y - bounds.y,
+                                             copy_bounds.width,
+                                             copy_bounds.height));
+    }
+
+  gimp_drawable_set_buffer_full (GIMP_DRAWABLE (mask),
+                                 FALSE, NULL,
+                                 buffer, &bounds,
+                                 TRUE);
+
+  g_object_unref (buffer);
+}
+
+static void
+gimp_group_layer_update_source_node (GimpGroupLayer *group)
+{
+  GimpGroupLayerPrivate *private = GET_PRIVATE (group);
+  GeglNode              *input;
+  GeglNode              *output;
+
+  if (private->source_node == NULL)
+    return;
+
+  input  = gegl_node_get_input_proxy  (private->source_node, "input");
+  output = gegl_node_get_output_proxy (private->source_node, "output");
+
+  if (private->pass_through)
+    {
+      gegl_node_connect_to (input,          "output",
+                            private->graph, "input");
+      gegl_node_connect_to (private->graph, "output",
+                            output,         "input");
+    }
+  else
+    {
+      gegl_node_disconnect (private->graph, "input");
+
+      gegl_node_connect_to (private->parent_source_node, "output",
+                            output,                      "input");
+    }
+}
+
+static void
+gimp_group_layer_update_mode_node (GimpGroupLayer *group)
+{
+  GimpGroupLayerPrivate *private = GET_PRIVATE (group);
+  GeglNode              *node;
+  GeglNode              *input;
+  GeglNode              *mode_node;
+
+  node      = gimp_filter_get_node (GIMP_FILTER (group));
+  input     = gegl_node_get_input_proxy (node, "input");
+  mode_node = gimp_drawable_get_mode_node (GIMP_DRAWABLE (group));
+
+  if (private->pass_through &&
+      gimp_layer_get_excludes_backdrop (GIMP_LAYER (group)))
+    {
+      gegl_node_disconnect (mode_node, "input");
+    }
+  else
+    {
+      gegl_node_connect_to (input,     "output",
+                            mode_node, "input");
+    }
+}
+
+static void
+gimp_group_layer_stack_update (GimpDrawableStack *stack,
+                               gint               x,
+                               gint               y,
+                               gint               width,
+                               gint               height,
+                               GimpGroupLayer    *group)
+{
+  GimpGroupLayerPrivate *private = GET_PRIVATE (group);
+
+#if 0
+  g_printerr ("%s (%s) %d, %d (%d, %d)\n",
+              G_STRFUNC, gimp_object_get_name (group),
+              x, y, width, height);
+#endif
+
+  if (! private->direct_update)
+    {
+      /*  the layer stack's update signal speaks in image coordinates,
+       *  pass to the projection as-is.
+       */
+      gimp_projectable_invalidate (GIMP_PROJECTABLE (group),
+                                   x, y, width, height);
+
+      gimp_group_layer_flush (group);
+    }
+
+  if (private->direct_update || private->pass_through)
+    {
+      /*  the layer stack's update signal speaks in image coordinates,
+       *  transform to layer coordinates when emitting our own update signal.
+       */
+      gimp_drawable_update (GIMP_DRAWABLE (group),
+                            x - gimp_item_get_offset_x (GIMP_ITEM (group)),
+                            y - gimp_item_get_offset_y (GIMP_ITEM (group)),
+                            width, height);
+    }
+}
+
+static void
+gimp_group_layer_proj_update (GimpProjection *proj,
+                              gboolean        now,
+                              gint            x,
+                              gint            y,
+                              gint            width,
+                              gint            height,
+                              GimpGroupLayer *group)
+{
+  GimpGroupLayerPrivate *private = GET_PRIVATE (group);
+
+#if 0
+  g_printerr ("%s (%s) %d, %d (%d, %d)\n",
+              G_STRFUNC, gimp_object_get_name (group),
+              x, y, width, height);
+#endif
+
+  if (! private->pass_through)
+    {
+      /* TODO: groups can currently have a gegl:transform op attached as a filter
+       * when using a transform tool, in which case the updated region needs
+       * undergo the same transformation.  more generally, when a drawable has
+       * filters they may influence the area affected by drawable updates.
+       *
+       * this needs to be addressed much more generally at some point, but for now
+       * we just resort to updating the entire group when it has a filter (i.e.,
+       * when it's being used with a transform tool).  we restrict this to groups,
+       * and don't do this more generally in gimp_drawable_update(), because this
+       * negatively impacts the performance of the warp tool, which does perform
+       * accurate drawable updates while using a filter.
+       */
+      if (gimp_drawable_has_filters (GIMP_DRAWABLE (group)))
+        {
+          width  = -1;
+          height = -1;
+        }
+
+      /*  the projection speaks in image coordinates, transform to layer
+       *  coordinates when emitting our own update signal.
+       */
+      gimp_drawable_update (GIMP_DRAWABLE (group),
+                            x - gimp_item_get_offset_x (GIMP_ITEM (group)),
+                            y - gimp_item_get_offset_y (GIMP_ITEM (group)),
+                            width, height);
+    }
+}
diff --git a/app/core/gimpgrouplayer.h b/app/core/gimpgrouplayer.h
new file mode 100644
index 0000000..5fef1e9
--- /dev/null
+++ b/app/core/gimpgrouplayer.h
@@ -0,0 +1,78 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * GimpGroupLayer
+ * Copyright (C) 2009  Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_GROUP_LAYER_H__
+#define __GIMP_GROUP_LAYER_H__
+
+
+#include "core/gimplayer.h"
+
+
+#define GIMP_TYPE_GROUP_LAYER            (gimp_group_layer_get_type ())
+#define GIMP_GROUP_LAYER(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_GROUP_LAYER, GimpGroupLayer))
+#define GIMP_GROUP_LAYER_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_GROUP_LAYER, GimpGroupLayerClass))
+#define GIMP_IS_GROUP_LAYER(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_GROUP_LAYER))
+#define GIMP_IS_GROUP_LAYER_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_GROUP_LAYER))
+#define GIMP_GROUP_LAYER_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_GROUP_LAYER, GimpGroupLayerClass))
+
+
+typedef struct _GimpGroupLayerClass GimpGroupLayerClass;
+
+struct _GimpGroupLayer
+{
+  GimpLayer  parent_instance;
+};
+
+struct _GimpGroupLayerClass
+{
+  GimpLayerClass  parent_class;
+};
+
+
+GType            gimp_group_layer_get_type            (void) G_GNUC_CONST;
+
+GimpLayer      * gimp_group_layer_new                 (GimpImage           *image);
+
+GimpProjection * gimp_group_layer_get_projection      (GimpGroupLayer      *group);
+
+void             gimp_group_layer_suspend_resize      (GimpGroupLayer      *group,
+                                                       gboolean             push_undo);
+void             gimp_group_layer_resume_resize       (GimpGroupLayer      *group,
+                                                       gboolean             push_undo);
+
+void             gimp_group_layer_suspend_mask        (GimpGroupLayer      *group,
+                                                       gboolean             push_undo);
+void             gimp_group_layer_resume_mask         (GimpGroupLayer      *group,
+                                                       gboolean             push_undo);
+
+
+void             _gimp_group_layer_set_suspended_mask (GimpGroupLayer      *group,
+                                                       GeglBuffer          *buffer,
+                                                       const GeglRectangle *bounds);
+GeglBuffer     * _gimp_group_layer_get_suspended_mask (GimpGroupLayer      *group,
+                                                       GeglRectangle       *bounds);
+
+void             _gimp_group_layer_start_transform    (GimpGroupLayer      *group,
+                                                       gboolean             push_undo);
+void             _gimp_group_layer_end_transform      (GimpGroupLayer      *group,
+                                                       gboolean             push_undo);
+
+
+#endif /* __GIMP_GROUP_LAYER_H__ */
diff --git a/app/core/gimpgrouplayerundo.c b/app/core/gimpgrouplayerundo.c
new file mode 100644
index 0000000..7ea70f4
--- /dev/null
+++ b/app/core/gimpgrouplayerundo.c
@@ -0,0 +1,253 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gimp-memsize.h"
+#include "gimpimage.h"
+#include "gimpgrouplayer.h"
+#include "gimpgrouplayerundo.h"
+
+
+static void     gimp_group_layer_undo_constructed (GObject             *object);
+
+static gint64   gimp_group_layer_undo_get_memsize (GimpObject          *object,
+                                                   gint64              *gui_size);
+
+static void     gimp_group_layer_undo_pop         (GimpUndo            *undo,
+                                                   GimpUndoMode         undo_mode,
+                                                   GimpUndoAccumulator *accum);
+static void     gimp_group_layer_undo_free        (GimpUndo            *undo,
+                                                   GimpUndoMode         undo_mode);
+
+
+G_DEFINE_TYPE (GimpGroupLayerUndo, gimp_group_layer_undo, GIMP_TYPE_ITEM_UNDO)
+
+#define parent_class gimp_group_layer_undo_parent_class
+
+
+static void
+gimp_group_layer_undo_class_init (GimpGroupLayerUndoClass *klass)
+{
+  GObjectClass    *object_class      = G_OBJECT_CLASS (klass);
+  GimpObjectClass *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+  GimpUndoClass   *undo_class        = GIMP_UNDO_CLASS (klass);
+
+  object_class->constructed      = gimp_group_layer_undo_constructed;
+
+  gimp_object_class->get_memsize = gimp_group_layer_undo_get_memsize;
+
+  undo_class->pop                = gimp_group_layer_undo_pop;
+  undo_class->free               = gimp_group_layer_undo_free;
+}
+
+static void
+gimp_group_layer_undo_init (GimpGroupLayerUndo *undo)
+{
+}
+
+static void
+gimp_group_layer_undo_constructed (GObject *object)
+{
+  GimpGroupLayerUndo *group_layer_undo = GIMP_GROUP_LAYER_UNDO (object);
+  GimpGroupLayer     *group;
+
+  G_OBJECT_CLASS (parent_class)->constructed (object);
+
+  g_return_if_fail (GIMP_IS_GROUP_LAYER (GIMP_ITEM_UNDO (object)->item));
+
+  group = GIMP_GROUP_LAYER (GIMP_ITEM_UNDO (object)->item);
+
+  switch (GIMP_UNDO (object)->undo_type)
+    {
+    case GIMP_UNDO_GROUP_LAYER_SUSPEND_RESIZE:
+    case GIMP_UNDO_GROUP_LAYER_RESUME_RESIZE:
+    case GIMP_UNDO_GROUP_LAYER_SUSPEND_MASK:
+    case GIMP_UNDO_GROUP_LAYER_START_TRANSFORM:
+    case GIMP_UNDO_GROUP_LAYER_END_TRANSFORM:
+      break;
+
+    case GIMP_UNDO_GROUP_LAYER_RESUME_MASK:
+      group_layer_undo->mask_buffer =
+        _gimp_group_layer_get_suspended_mask(group,
+                                             &group_layer_undo->mask_bounds);
+
+      if (group_layer_undo->mask_buffer)
+        g_object_ref (group_layer_undo->mask_buffer);
+      break;
+
+    case GIMP_UNDO_GROUP_LAYER_CONVERT:
+      group_layer_undo->prev_type = gimp_drawable_get_base_type (GIMP_DRAWABLE (group));
+      group_layer_undo->prev_precision = gimp_drawable_get_precision (GIMP_DRAWABLE (group));
+      group_layer_undo->prev_has_alpha = gimp_drawable_has_alpha (GIMP_DRAWABLE (group));
+      break;
+
+    default:
+      g_return_if_reached ();
+    }
+}
+
+static gint64
+gimp_group_layer_undo_get_memsize (GimpObject *object,
+                                   gint64     *gui_size)
+{
+  GimpGroupLayerUndo *group_layer_undo = GIMP_GROUP_LAYER_UNDO (object);
+  gint64              memsize       = 0;
+
+  memsize += gimp_gegl_buffer_get_memsize (group_layer_undo->mask_buffer);
+
+  return memsize + GIMP_OBJECT_CLASS (parent_class)->get_memsize (object,
+                                                                  gui_size);
+}
+
+static void
+gimp_group_layer_undo_pop (GimpUndo            *undo,
+                           GimpUndoMode         undo_mode,
+                           GimpUndoAccumulator *accum)
+{
+  GimpGroupLayerUndo *group_layer_undo = GIMP_GROUP_LAYER_UNDO (undo);
+  GimpGroupLayer     *group;
+
+  group = GIMP_GROUP_LAYER (GIMP_ITEM_UNDO (undo)->item);
+
+  GIMP_UNDO_CLASS (parent_class)->pop (undo, undo_mode, accum);
+
+  switch (undo->undo_type)
+    {
+    case GIMP_UNDO_GROUP_LAYER_SUSPEND_RESIZE:
+    case GIMP_UNDO_GROUP_LAYER_RESUME_RESIZE:
+      if ((undo_mode       == GIMP_UNDO_MODE_UNDO &&
+           undo->undo_type == GIMP_UNDO_GROUP_LAYER_SUSPEND_RESIZE) ||
+          (undo_mode       == GIMP_UNDO_MODE_REDO &&
+           undo->undo_type == GIMP_UNDO_GROUP_LAYER_RESUME_RESIZE))
+        {
+          /*  resume group layer auto-resizing  */
+
+          gimp_group_layer_resume_resize (group, FALSE);
+        }
+      else
+        {
+          /*  suspend group layer auto-resizing  */
+
+          gimp_group_layer_suspend_resize (group, FALSE);
+
+          if (undo->undo_type == GIMP_UNDO_GROUP_LAYER_RESUME_RESIZE &&
+              group_layer_undo->mask_buffer)
+            {
+              GimpLayerMask *mask = gimp_layer_get_mask (GIMP_LAYER (group));
+
+              gimp_drawable_set_buffer_full (GIMP_DRAWABLE (mask),
+                                             FALSE, NULL,
+                                             group_layer_undo->mask_buffer,
+                                             &group_layer_undo->mask_bounds,
+                                             TRUE);
+            }
+        }
+      break;
+
+    case GIMP_UNDO_GROUP_LAYER_SUSPEND_MASK:
+    case GIMP_UNDO_GROUP_LAYER_RESUME_MASK:
+      if ((undo_mode       == GIMP_UNDO_MODE_UNDO &&
+           undo->undo_type == GIMP_UNDO_GROUP_LAYER_SUSPEND_MASK) ||
+          (undo_mode       == GIMP_UNDO_MODE_REDO &&
+           undo->undo_type == GIMP_UNDO_GROUP_LAYER_RESUME_MASK))
+        {
+          /*  resume group layer mask auto-resizing  */
+
+          gimp_group_layer_resume_mask (group, FALSE);
+        }
+      else
+        {
+          /*  suspend group layer mask auto-resizing  */
+
+          gimp_group_layer_suspend_mask (group, FALSE);
+
+          if (undo->undo_type == GIMP_UNDO_GROUP_LAYER_RESUME_MASK &&
+              group_layer_undo->mask_buffer)
+            {
+              _gimp_group_layer_set_suspended_mask (
+                group,
+                group_layer_undo->mask_buffer,
+                &group_layer_undo->mask_bounds);
+            }
+        }
+      break;
+
+    case GIMP_UNDO_GROUP_LAYER_START_TRANSFORM:
+    case GIMP_UNDO_GROUP_LAYER_END_TRANSFORM:
+      if ((undo_mode       == GIMP_UNDO_MODE_UNDO &&
+           undo->undo_type == GIMP_UNDO_GROUP_LAYER_START_TRANSFORM) ||
+          (undo_mode       == GIMP_UNDO_MODE_REDO &&
+           undo->undo_type == GIMP_UNDO_GROUP_LAYER_END_TRANSFORM))
+        {
+          /*  end group layer transform operation  */
+
+          _gimp_group_layer_end_transform (group, FALSE);
+        }
+      else
+        {
+          /*  start group layer transform operation  */
+
+          _gimp_group_layer_start_transform (group, FALSE);
+        }
+      break;
+
+    case GIMP_UNDO_GROUP_LAYER_CONVERT:
+      {
+        GimpImageBaseType type;
+        GimpPrecision     precision;
+        gboolean          has_alpha;
+
+        type      = gimp_drawable_get_base_type (GIMP_DRAWABLE (group));
+        precision = gimp_drawable_get_precision (GIMP_DRAWABLE (group));
+        has_alpha = gimp_drawable_has_alpha (GIMP_DRAWABLE (group));
+
+        gimp_drawable_convert_type (GIMP_DRAWABLE (group),
+                                    gimp_item_get_image (GIMP_ITEM (group)),
+                                    group_layer_undo->prev_type,
+                                    group_layer_undo->prev_precision,
+                                    group_layer_undo->prev_has_alpha,
+                                    NULL,
+                                    0, 0,
+                                    FALSE, NULL);
+
+        group_layer_undo->prev_type      = type;
+        group_layer_undo->prev_precision = precision;
+        group_layer_undo->prev_has_alpha = has_alpha;
+      }
+      break;
+
+    default:
+      g_return_if_reached ();
+    }
+}
+
+static void
+gimp_group_layer_undo_free (GimpUndo     *undo,
+                            GimpUndoMode  undo_mode)
+{
+  GimpGroupLayerUndo *group_layer_undo = GIMP_GROUP_LAYER_UNDO (undo);
+
+  g_clear_object (&group_layer_undo->mask_buffer);
+
+  GIMP_UNDO_CLASS (parent_class)->free (undo, undo_mode);
+}
diff --git a/app/core/gimpgrouplayerundo.h b/app/core/gimpgrouplayerundo.h
new file mode 100644
index 0000000..14c7043
--- /dev/null
+++ b/app/core/gimpgrouplayerundo.h
@@ -0,0 +1,57 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_GROUP_LAYER_UNDO_H__
+#define __GIMP_GROUP_LAYER_UNDO_H__
+
+
+#include "gimpitemundo.h"
+
+
+#define GIMP_TYPE_GROUP_LAYER_UNDO            (gimp_group_layer_undo_get_type ())
+#define GIMP_GROUP_LAYER_UNDO(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_GROUP_LAYER_UNDO, GimpGroupLayerUndo))
+#define GIMP_GROUP_LAYER_UNDO_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_GROUP_LAYER_UNDO, GimpGroupLayerUndoClass))
+#define GIMP_IS_GROUP_LAYER_UNDO(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_GROUP_LAYER_UNDO))
+#define GIMP_IS_GROUP_LAYER_UNDO_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_GROUP_LAYER_UNDO))
+#define GIMP_GROUP_LAYER_UNDO_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_GROUP_LAYER_UNDO, GimpGroupLayerUndoClass))
+
+
+typedef struct _GimpGroupLayerUndo      GimpGroupLayerUndo;
+typedef struct _GimpGroupLayerUndoClass GimpGroupLayerUndoClass;
+
+struct _GimpGroupLayerUndo
+{
+  GimpItemUndo       parent_instance;
+
+  GeglBuffer        *mask_buffer;
+  GeglRectangle      mask_bounds;
+
+  GimpImageBaseType  prev_type;
+  GimpPrecision      prev_precision;
+  gboolean           prev_has_alpha;
+};
+
+struct _GimpGroupLayerUndoClass
+{
+  GimpItemUndoClass  parent_class;
+};
+
+
+GType   gimp_group_layer_undo_get_type (void) G_GNUC_CONST;
+
+
+#endif /* __GIMP_GROUP_LAYER_UNDO_H__ */
diff --git a/app/core/gimpguide.c b/app/core/gimpguide.c
new file mode 100644
index 0000000..1438958
--- /dev/null
+++ b/app/core/gimpguide.c
@@ -0,0 +1,242 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * GimpGuide
+ * Copyright (C) 2003  Henrik Brix Andersen <brix@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gio/gio.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpconfig/gimpconfig.h"
+
+#include "core-types.h"
+
+#include "gimpguide.h"
+
+
+enum
+{
+  PROP_0,
+  PROP_ORIENTATION,
+  PROP_POSITION,
+  PROP_STYLE
+};
+
+
+struct _GimpGuidePrivate
+{
+  GimpOrientationType  orientation;
+  gint                 position;
+
+  GimpGuideStyle       style;
+};
+
+
+static void   gimp_guide_get_property (GObject      *object,
+                                       guint         property_id,
+                                       GValue       *value,
+                                       GParamSpec   *pspec);
+static void   gimp_guide_set_property (GObject      *object,
+                                       guint         property_id,
+                                       const GValue *value,
+                                       GParamSpec   *pspec);
+
+
+G_DEFINE_TYPE_WITH_PRIVATE (GimpGuide, gimp_guide, GIMP_TYPE_AUX_ITEM)
+
+
+static void
+gimp_guide_class_init (GimpGuideClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  object_class->get_property = gimp_guide_get_property;
+  object_class->set_property = gimp_guide_set_property;
+
+  GIMP_CONFIG_PROP_ENUM (object_class, PROP_ORIENTATION,
+                         "orientation",
+                         NULL, NULL,
+                         GIMP_TYPE_ORIENTATION_TYPE,
+                         GIMP_ORIENTATION_UNKNOWN,
+                         0);
+
+  GIMP_CONFIG_PROP_INT (object_class, PROP_POSITION,
+                        "position",
+                        NULL, NULL,
+                        GIMP_GUIDE_POSITION_UNDEFINED,
+                        GIMP_MAX_IMAGE_SIZE,
+                        GIMP_GUIDE_POSITION_UNDEFINED,
+                        0);
+
+  GIMP_CONFIG_PROP_ENUM (object_class, PROP_STYLE,
+                         "style",
+                         NULL, NULL,
+                         GIMP_TYPE_GUIDE_STYLE,
+                         GIMP_GUIDE_STYLE_NONE,
+                         0);
+}
+
+static void
+gimp_guide_init (GimpGuide *guide)
+{
+  guide->priv = gimp_guide_get_instance_private (guide);
+}
+
+static void
+gimp_guide_get_property (GObject    *object,
+                         guint       property_id,
+                         GValue     *value,
+                         GParamSpec *pspec)
+{
+  GimpGuide *guide = GIMP_GUIDE (object);
+
+  switch (property_id)
+    {
+    case PROP_ORIENTATION:
+      g_value_set_enum (value, guide->priv->orientation);
+      break;
+    case PROP_POSITION:
+      g_value_set_int (value, guide->priv->position);
+      break;
+    case PROP_STYLE:
+      g_value_set_enum (value, guide->priv->style);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_guide_set_property (GObject      *object,
+                         guint         property_id,
+                         const GValue *value,
+                         GParamSpec   *pspec)
+{
+  GimpGuide *guide = GIMP_GUIDE (object);
+
+  switch (property_id)
+    {
+    case PROP_ORIENTATION:
+      guide->priv->orientation = g_value_get_enum (value);
+      break;
+    case PROP_POSITION:
+      guide->priv->position = g_value_get_int (value);
+      break;
+    case PROP_STYLE:
+      guide->priv->style = g_value_get_enum (value);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+GimpGuide *
+gimp_guide_new (GimpOrientationType  orientation,
+                guint32              guide_ID)
+{
+  return g_object_new (GIMP_TYPE_GUIDE,
+                       "id",          guide_ID,
+                       "orientation", orientation,
+                       "style",       GIMP_GUIDE_STYLE_NORMAL,
+                       NULL);
+}
+
+/**
+ * gimp_guide_custom_new:
+ * @orientation:       the #GimpOrientationType
+ * @guide_ID:          the unique guide ID
+ * @guide_style:       the #GimpGuideStyle
+ *
+ * This function returns a new guide and will flag it as "custom".
+ * Custom guides are used for purpose "other" than the basic guides
+ * a user can create oneself, for instance as symmetry guides, to
+ * drive GEGL ops, etc.
+ * They are not saved in the XCF file. If an op, a symmetry or a plugin
+ * wishes to save its state, it has to do it internally.
+ * Moreover they don't follow guide snapping settings and never snap.
+ *
+ * Returns: the custom #GimpGuide.
+ **/
+GimpGuide *
+gimp_guide_custom_new (GimpOrientationType  orientation,
+                       guint32              guide_ID,
+                       GimpGuideStyle       guide_style)
+{
+  return g_object_new (GIMP_TYPE_GUIDE,
+                       "id",          guide_ID,
+                       "orientation", orientation,
+                       "style",       guide_style,
+                       NULL);
+}
+
+GimpOrientationType
+gimp_guide_get_orientation (GimpGuide *guide)
+{
+  g_return_val_if_fail (GIMP_IS_GUIDE (guide), GIMP_ORIENTATION_UNKNOWN);
+
+  return guide->priv->orientation;
+}
+
+void
+gimp_guide_set_orientation (GimpGuide           *guide,
+                            GimpOrientationType  orientation)
+{
+  g_return_if_fail (GIMP_IS_GUIDE (guide));
+
+  guide->priv->orientation = orientation;
+
+  g_object_notify (G_OBJECT (guide), "orientation");
+}
+
+gint
+gimp_guide_get_position (GimpGuide *guide)
+{
+  g_return_val_if_fail (GIMP_IS_GUIDE (guide), GIMP_GUIDE_POSITION_UNDEFINED);
+
+  return guide->priv->position;
+}
+
+void
+gimp_guide_set_position (GimpGuide *guide,
+                         gint       position)
+{
+  g_return_if_fail (GIMP_IS_GUIDE (guide));
+
+  guide->priv->position = position;
+
+  g_object_notify (G_OBJECT (guide), "position");
+}
+
+GimpGuideStyle
+gimp_guide_get_style (GimpGuide *guide)
+{
+  g_return_val_if_fail (GIMP_IS_GUIDE (guide), GIMP_GUIDE_STYLE_NONE);
+
+  return guide->priv->style;
+}
+
+gboolean
+gimp_guide_is_custom (GimpGuide *guide)
+{
+  g_return_val_if_fail (GIMP_IS_GUIDE (guide), FALSE);
+
+  return guide->priv->style != GIMP_GUIDE_STYLE_NORMAL;
+}
diff --git a/app/core/gimpguide.h b/app/core/gimpguide.h
new file mode 100644
index 0000000..285e8eb
--- /dev/null
+++ b/app/core/gimpguide.h
@@ -0,0 +1,75 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * GimpGuide
+ * Copyright (C) 2003  Henrik Brix Andersen <brix@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_GUIDE_H__
+#define __GIMP_GUIDE_H__
+
+
+#include "gimpauxitem.h"
+
+
+#define GIMP_GUIDE_POSITION_UNDEFINED G_MININT
+
+
+#define GIMP_TYPE_GUIDE            (gimp_guide_get_type ())
+#define GIMP_GUIDE(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_GUIDE, GimpGuide))
+#define GIMP_GUIDE_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_GUIDE, GimpGuideClass))
+#define GIMP_IS_GUIDE(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_GUIDE))
+#define GIMP_IS_GUIDE_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_GUIDE))
+#define GIMP_GUIDE_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_GUIDE, GimpGuideClass))
+
+
+typedef struct _GimpGuidePrivate GimpGuidePrivate;
+typedef struct _GimpGuideClass   GimpGuideClass;
+
+struct _GimpGuide
+{
+  GimpAuxItem       parent_instance;
+
+  GimpGuidePrivate *priv;
+};
+
+struct _GimpGuideClass
+{
+  GimpAuxItemClass  parent_class;
+};
+
+
+GType               gimp_guide_get_type         (void) G_GNUC_CONST;
+
+GimpGuide *         gimp_guide_new              (GimpOrientationType  orientation,
+                                                 guint32              guide_ID);
+GimpGuide *         gimp_guide_custom_new       (GimpOrientationType  orientation,
+                                                 guint32              guide_ID,
+                                                 GimpGuideStyle       guide_style);
+
+GimpOrientationType gimp_guide_get_orientation  (GimpGuide           *guide);
+void                gimp_guide_set_orientation  (GimpGuide           *guide,
+                                                 GimpOrientationType  orientation);
+
+gint                gimp_guide_get_position     (GimpGuide           *guide);
+void                gimp_guide_set_position     (GimpGuide           *guide,
+                                                 gint                 position);
+
+GimpGuideStyle      gimp_guide_get_style        (GimpGuide           *guide);
+gboolean            gimp_guide_is_custom        (GimpGuide           *guide);
+
+
+#endif /* __GIMP_GUIDE_H__ */
diff --git a/app/core/gimpguideundo.c b/app/core/gimpguideundo.c
new file mode 100644
index 0000000..c3e3de4
--- /dev/null
+++ b/app/core/gimpguideundo.c
@@ -0,0 +1,116 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gimpimage.h"
+#include "gimpimage-guides.h"
+#include "gimpguide.h"
+#include "gimpguideundo.h"
+
+
+static void   gimp_guide_undo_constructed  (GObject            *object);
+
+static void   gimp_guide_undo_pop          (GimpUndo            *undo,
+                                            GimpUndoMode         undo_mode,
+                                            GimpUndoAccumulator *accum);
+
+
+G_DEFINE_TYPE (GimpGuideUndo, gimp_guide_undo,
+               GIMP_TYPE_AUX_ITEM_UNDO)
+
+#define parent_class gimp_guide_undo_parent_class
+
+
+static void
+gimp_guide_undo_class_init (GimpGuideUndoClass *klass)
+{
+  GObjectClass  *object_class = G_OBJECT_CLASS (klass);
+  GimpUndoClass *undo_class   = GIMP_UNDO_CLASS (klass);
+
+  object_class->constructed = gimp_guide_undo_constructed;
+
+  undo_class->pop           = gimp_guide_undo_pop;
+}
+
+static void
+gimp_guide_undo_init (GimpGuideUndo *undo)
+{
+}
+
+static void
+gimp_guide_undo_constructed (GObject *object)
+{
+  GimpGuideUndo *guide_undo = GIMP_GUIDE_UNDO (object);
+  GimpGuide     *guide;
+
+  G_OBJECT_CLASS (parent_class)->constructed (object);
+
+  guide = GIMP_GUIDE (GIMP_AUX_ITEM_UNDO (object)->aux_item);
+
+  gimp_assert (GIMP_IS_GUIDE (guide));
+
+  guide_undo->orientation = gimp_guide_get_orientation (guide);
+  guide_undo->position    = gimp_guide_get_position (guide);
+}
+
+static void
+gimp_guide_undo_pop (GimpUndo              *undo,
+                     GimpUndoMode           undo_mode,
+                     GimpUndoAccumulator   *accum)
+{
+  GimpGuideUndo       *guide_undo = GIMP_GUIDE_UNDO (undo);
+  GimpGuide           *guide;
+  GimpOrientationType  orientation;
+  gint                 position;
+  gboolean             moved = FALSE;
+
+  GIMP_UNDO_CLASS (parent_class)->pop (undo, undo_mode, accum);
+
+  guide = GIMP_GUIDE (GIMP_AUX_ITEM_UNDO (undo)->aux_item);
+
+  orientation = gimp_guide_get_orientation (guide);
+  position    = gimp_guide_get_position (guide);
+
+  if (position == GIMP_GUIDE_POSITION_UNDEFINED)
+    {
+      gimp_image_add_guide (undo->image, guide, guide_undo->position);
+    }
+  else if (guide_undo->position == GIMP_GUIDE_POSITION_UNDEFINED)
+    {
+      gimp_image_remove_guide (undo->image, guide, FALSE);
+    }
+  else
+    {
+      gimp_guide_set_position (guide, guide_undo->position);
+
+      moved = TRUE;
+    }
+
+  gimp_guide_set_orientation (guide, guide_undo->orientation);
+
+  if (moved || guide_undo->orientation != orientation)
+    gimp_image_guide_moved (undo->image, guide);
+
+  guide_undo->position    = position;
+  guide_undo->orientation = orientation;
+}
diff --git a/app/core/gimpguideundo.h b/app/core/gimpguideundo.h
new file mode 100644
index 0000000..da77ff3
--- /dev/null
+++ b/app/core/gimpguideundo.h
@@ -0,0 +1,53 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_GUIDE_UNDO_H__
+#define __GIMP_GUIDE_UNDO_H__
+
+
+#include "gimpauxitemundo.h"
+
+
+#define GIMP_TYPE_GUIDE_UNDO            (gimp_guide_undo_get_type ())
+#define GIMP_GUIDE_UNDO(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_GUIDE_UNDO, GimpGuideUndo))
+#define GIMP_GUIDE_UNDO_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_GUIDE_UNDO, GimpGuideUndoClass))
+#define GIMP_IS_GUIDE_UNDO(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_GUIDE_UNDO))
+#define GIMP_IS_GUIDE_UNDO_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_GUIDE_UNDO))
+#define GIMP_GUIDE_UNDO_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_GUIDE_UNDO, GimpGuideUndoClass))
+
+
+typedef struct _GimpGuideUndo      GimpGuideUndo;
+typedef struct _GimpGuideUndoClass GimpGuideUndoClass;
+
+struct _GimpGuideUndo
+{
+  GimpAuxItemUndo      parent_instance;
+
+  GimpOrientationType  orientation;
+  gint                 position;
+};
+
+struct _GimpGuideUndoClass
+{
+  GimpAuxItemUndoClass  parent_class;
+};
+
+
+GType   gimp_guide_undo_get_type (void) G_GNUC_CONST;
+
+
+#endif /* __GIMP_GUIDE_UNDO_H__ */
diff --git a/app/core/gimphistogram.c b/app/core/gimphistogram.c
new file mode 100644
index 0000000..571679b
--- /dev/null
+++ b/app/core/gimphistogram.c
@@ -0,0 +1,1261 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimphistogram module Copyright (C) 1999 Jay Cox <jaycox@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+#include <cairo.h>
+#include <gegl.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "libgimpmath/gimpmath.h"
+#include "libgimpcolor/gimpcolor.h"
+
+#include "core-types.h"
+
+#include "gegl/gimp-babl.h"
+#include "gegl/gimp-gegl-loops.h"
+
+#include "gimp-atomic.h"
+#include "gimp-parallel.h"
+#include "gimpasync.h"
+#include "gimphistogram.h"
+#include "gimpwaitable.h"
+
+
+#define MAX_N_COMPONENTS   4
+#define N_DERIVED_CHANNELS 2
+
+#define PIXELS_PER_THREAD \
+  (/* each thread costs as much as */ 64.0 * 64.0 /* pixels */)
+
+
+enum
+{
+  PROP_0,
+  PROP_N_COMPONENTS,
+  PROP_N_BINS,
+  PROP_VALUES
+};
+
+struct _GimpHistogramPrivate
+{
+  gboolean   linear;
+  gint       n_channels;
+  gint       n_bins;
+  gdouble   *values;
+  GimpAsync *calculate_async;
+};
+
+typedef struct
+{
+  /*  input  */
+  GimpHistogram *histogram;
+  GeglBuffer    *buffer;
+  GeglRectangle  buffer_rect;
+  GeglBuffer    *mask;
+  GeglRectangle  mask_rect;
+
+  /*  output  */
+  gint           n_components;
+  gint           n_bins;
+  gdouble       *values;
+} CalculateContext;
+
+typedef struct
+{
+  GimpAsync        *async;
+  CalculateContext *context;
+
+  const Babl       *format;
+  GSList           *values_list;
+} CalculateData;
+
+
+/*  local function prototypes  */
+
+static void       gimp_histogram_finalize                 (GObject              *object);
+static void       gimp_histogram_set_property             (GObject              *object,
+                                                           guint                 property_id,
+                                                           const GValue         *value,
+                                                           GParamSpec           *pspec);
+static void       gimp_histogram_get_property             (GObject              *object,
+                                                           guint                 property_id,
+                                                           GValue               *value,
+                                                           GParamSpec           *pspec);
+
+static gint64     gimp_histogram_get_memsize              (GimpObject           *object,
+                                                           gint64               *gui_size);
+
+static gboolean   gimp_histogram_map_channel              (GimpHistogram        *histogram,
+                                                           GimpHistogramChannel *channel);
+
+static void       gimp_histogram_set_values               (GimpHistogram        *histogram,
+                                                           gint                  n_components,
+                                                           gint                  n_bins,
+                                                           gdouble              *values);
+
+static void       gimp_histogram_calculate_internal       (GimpAsync            *async,
+                                                           CalculateContext     *context);
+static void       gimp_histogram_calculate_area           (const GeglRectangle  *area,
+                                                           CalculateData        *data);
+static void       gimp_histogram_calculate_async_callback (GimpAsync            *async,
+                                                           CalculateContext     *context);
+
+
+G_DEFINE_TYPE_WITH_PRIVATE (GimpHistogram, gimp_histogram, GIMP_TYPE_OBJECT)
+
+#define parent_class gimp_histogram_parent_class
+
+
+static void
+gimp_histogram_class_init (GimpHistogramClass *klass)
+{
+  GObjectClass      *object_class      = G_OBJECT_CLASS (klass);
+  GimpObjectClass   *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+
+  object_class->finalize         = gimp_histogram_finalize;
+  object_class->set_property     = gimp_histogram_set_property;
+  object_class->get_property     = gimp_histogram_get_property;
+
+  gimp_object_class->get_memsize = gimp_histogram_get_memsize;
+
+  g_object_class_install_property (object_class, PROP_N_COMPONENTS,
+                                   g_param_spec_int ("n-components", NULL, NULL,
+                                                     0, MAX_N_COMPONENTS, 0,
+                                                     GIMP_PARAM_READABLE));
+
+  g_object_class_install_property (object_class, PROP_N_BINS,
+                                   g_param_spec_int ("n-bins", NULL, NULL,
+                                                     256, 1024, 1024,
+                                                     GIMP_PARAM_READABLE));
+
+  /* this is just for notifications */
+  g_object_class_install_property (object_class, PROP_VALUES,
+                                   g_param_spec_boolean ("values", NULL, NULL,
+                                                         FALSE,
+                                                         G_PARAM_READABLE));
+}
+
+static void
+gimp_histogram_init (GimpHistogram *histogram)
+{
+  histogram->priv = gimp_histogram_get_instance_private (histogram);
+}
+
+static void
+gimp_histogram_finalize (GObject *object)
+{
+  GimpHistogram *histogram = GIMP_HISTOGRAM (object);
+
+  gimp_histogram_clear_values (histogram, 0);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gimp_histogram_set_property (GObject      *object,
+                             guint         property_id,
+                             const GValue *value,
+                             GParamSpec   *pspec)
+{
+  switch (property_id)
+    {
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_histogram_get_property (GObject    *object,
+                             guint       property_id,
+                             GValue     *value,
+                             GParamSpec *pspec)
+{
+  GimpHistogram *histogram = GIMP_HISTOGRAM (object);
+
+  switch (property_id)
+    {
+    case PROP_N_COMPONENTS:
+      g_value_set_int (value, gimp_histogram_n_components (histogram));
+      break;
+
+    case PROP_N_BINS:
+      g_value_set_int (value, histogram->priv->n_bins);
+      break;
+
+    case PROP_VALUES:
+      /* return a silly boolean */
+      g_value_set_boolean (value, histogram->priv->values != NULL);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static gint64
+gimp_histogram_get_memsize (GimpObject *object,
+                            gint64     *gui_size)
+{
+  GimpHistogram *histogram = GIMP_HISTOGRAM (object);
+  gint64         memsize   = 0;
+
+  if (histogram->priv->values)
+    memsize += (histogram->priv->n_channels *
+                histogram->priv->n_bins * sizeof (gdouble));
+
+  return memsize + GIMP_OBJECT_CLASS (parent_class)->get_memsize (object,
+                                                                  gui_size);
+}
+
+/*  public functions  */
+
+GimpHistogram *
+gimp_histogram_new (gboolean linear)
+{
+  GimpHistogram *histogram = g_object_new (GIMP_TYPE_HISTOGRAM, NULL);
+
+  histogram->priv->linear = linear;
+
+  return histogram;
+}
+
+/**
+ * gimp_histogram_duplicate:
+ * @histogram: a %GimpHistogram
+ *
+ * Creates a duplicate of @histogram. The duplicate has a reference
+ * count of 1 and contains the values from @histogram.
+ *
+ * Return value: a newly allocated %GimpHistogram
+ **/
+GimpHistogram *
+gimp_histogram_duplicate (GimpHistogram *histogram)
+{
+  GimpHistogram *dup;
+
+  g_return_val_if_fail (GIMP_IS_HISTOGRAM (histogram), NULL);
+
+  if (histogram->priv->calculate_async)
+    gimp_waitable_wait (GIMP_WAITABLE (histogram->priv->calculate_async));
+
+  dup = gimp_histogram_new (histogram->priv->linear);
+
+  dup->priv->n_channels = histogram->priv->n_channels;
+  dup->priv->n_bins     = histogram->priv->n_bins;
+  dup->priv->values     = g_memdup (histogram->priv->values,
+                                    sizeof (gdouble) *
+                                    dup->priv->n_channels *
+                                    dup->priv->n_bins);
+
+  return dup;
+}
+
+void
+gimp_histogram_calculate (GimpHistogram       *histogram,
+                          GeglBuffer          *buffer,
+                          const GeglRectangle *buffer_rect,
+                          GeglBuffer          *mask,
+                          const GeglRectangle *mask_rect)
+{
+  CalculateContext context = {};
+
+  g_return_if_fail (GIMP_IS_HISTOGRAM (histogram));
+  g_return_if_fail (GEGL_IS_BUFFER (buffer));
+  g_return_if_fail (buffer_rect != NULL);
+
+  if (histogram->priv->calculate_async)
+    gimp_async_cancel_and_wait (histogram->priv->calculate_async);
+
+  context.histogram   = histogram;
+  context.buffer      = buffer;
+  context.buffer_rect = *buffer_rect;
+
+  if (mask)
+    {
+      context.mask = mask;
+
+      if (mask_rect)
+        context.mask_rect = *mask_rect;
+      else
+        context.mask_rect = *gegl_buffer_get_extent (mask);
+    }
+
+  gimp_histogram_calculate_internal (NULL, &context);
+
+  gimp_histogram_set_values (histogram,
+                             context.n_components, context.n_bins,
+                             context.values);
+}
+
+GimpAsync *
+gimp_histogram_calculate_async (GimpHistogram       *histogram,
+                                GeglBuffer          *buffer,
+                                const GeglRectangle *buffer_rect,
+                                GeglBuffer          *mask,
+                                const GeglRectangle *mask_rect)
+{
+  CalculateContext *context;
+  GeglRectangle     rect;
+
+  g_return_val_if_fail (GIMP_IS_HISTOGRAM (histogram), NULL);
+  g_return_val_if_fail (GEGL_IS_BUFFER (buffer), NULL);
+  g_return_val_if_fail (buffer_rect != NULL, NULL);
+
+  if (histogram->priv->calculate_async)
+    gimp_async_cancel_and_wait (histogram->priv->calculate_async);
+
+  gegl_rectangle_align_to_buffer (&rect, buffer_rect, buffer,
+                                  GEGL_RECTANGLE_ALIGNMENT_SUPERSET);
+
+  context = g_slice_new0 (CalculateContext);
+
+  context->histogram   = histogram;
+  context->buffer      = gegl_buffer_new (&rect,
+                                          gegl_buffer_get_format (buffer));
+  context->buffer_rect = *buffer_rect;
+
+  gimp_gegl_buffer_copy (buffer, &rect, GEGL_ABYSS_NONE,
+                         context->buffer, NULL);
+
+  if (mask)
+    {
+      if (mask_rect)
+        context->mask_rect = *mask_rect;
+      else
+        context->mask_rect = *gegl_buffer_get_extent (mask);
+
+      gegl_rectangle_align_to_buffer (&rect, &context->mask_rect, mask,
+                                      GEGL_RECTANGLE_ALIGNMENT_SUPERSET);
+
+      context->mask = gegl_buffer_new (&rect, gegl_buffer_get_format (mask));
+
+      gimp_gegl_buffer_copy (mask, &rect, GEGL_ABYSS_NONE,
+                             context->mask, NULL);
+    }
+
+  histogram->priv->calculate_async = gimp_parallel_run_async (
+    (GimpRunAsyncFunc) gimp_histogram_calculate_internal,
+    context);
+
+  gimp_async_add_callback (
+    histogram->priv->calculate_async,
+    (GimpAsyncCallback) gimp_histogram_calculate_async_callback,
+    context);
+
+  return histogram->priv->calculate_async;
+}
+
+void
+gimp_histogram_clear_values (GimpHistogram *histogram,
+                             gint           n_components)
+{
+  g_return_if_fail (GIMP_IS_HISTOGRAM (histogram));
+
+  if (histogram->priv->calculate_async)
+    gimp_async_cancel_and_wait (histogram->priv->calculate_async);
+
+  gimp_histogram_set_values (histogram, n_components, 0, NULL);
+}
+
+
+#define HISTOGRAM_VALUE(c,i) (priv->values[(c) * priv->n_bins + (i)])
+
+
+gdouble
+gimp_histogram_get_maximum (GimpHistogram        *histogram,
+                            GimpHistogramChannel  channel)
+{
+  GimpHistogramPrivate *priv;
+  gdouble               max = 0.0;
+  gint                  x;
+
+  g_return_val_if_fail (GIMP_IS_HISTOGRAM (histogram), 0.0);
+
+  priv = histogram->priv;
+
+  if (! priv->values ||
+      ! gimp_histogram_map_channel (histogram, &channel))
+    {
+      return 0.0;
+    }
+
+  if (channel == GIMP_HISTOGRAM_RGB)
+    {
+      for (x = 0; x < priv->n_bins; x++)
+        {
+          max = MAX (max, HISTOGRAM_VALUE (GIMP_HISTOGRAM_RED,   x));
+          max = MAX (max, HISTOGRAM_VALUE (GIMP_HISTOGRAM_GREEN, x));
+          max = MAX (max, HISTOGRAM_VALUE (GIMP_HISTOGRAM_BLUE,  x));
+        }
+    }
+  else
+    {
+      for (x = 0; x < priv->n_bins; x++)
+        {
+          max = MAX (max, HISTOGRAM_VALUE (channel, x));
+        }
+    }
+
+  return max;
+}
+
+gdouble
+gimp_histogram_get_value (GimpHistogram        *histogram,
+                          GimpHistogramChannel  channel,
+                          gint                  bin)
+{
+  GimpHistogramPrivate *priv;
+
+  g_return_val_if_fail (GIMP_IS_HISTOGRAM (histogram), 0.0);
+
+  priv = histogram->priv;
+
+  if (! priv->values                   ||
+      (bin < 0 || bin >= priv->n_bins) ||
+      ! gimp_histogram_map_channel (histogram, &channel))
+    {
+      return 0.0;
+    }
+
+  if (channel == GIMP_HISTOGRAM_RGB)
+    {
+      gdouble min = HISTOGRAM_VALUE (GIMP_HISTOGRAM_RED, bin);
+
+      min = MIN (min, HISTOGRAM_VALUE (GIMP_HISTOGRAM_GREEN, bin));
+
+      return MIN (min, HISTOGRAM_VALUE (GIMP_HISTOGRAM_BLUE, bin));
+    }
+  else
+    {
+      return HISTOGRAM_VALUE (channel, bin);
+    }
+}
+
+gdouble
+gimp_histogram_get_component (GimpHistogram *histogram,
+                              gint           component,
+                              gint           bin)
+{
+  g_return_val_if_fail (GIMP_IS_HISTOGRAM (histogram), 0.0);
+
+  if (gimp_histogram_n_components (histogram) > 2)
+    component++;
+
+  return gimp_histogram_get_value (histogram, component, bin);
+}
+
+gint
+gimp_histogram_n_components (GimpHistogram *histogram)
+{
+  g_return_val_if_fail (GIMP_IS_HISTOGRAM (histogram), 0);
+
+  if (histogram->priv->n_channels > 0)
+    return histogram->priv->n_channels - N_DERIVED_CHANNELS;
+  else
+    return 0;
+}
+
+gint
+gimp_histogram_n_bins (GimpHistogram *histogram)
+{
+  g_return_val_if_fail (GIMP_IS_HISTOGRAM (histogram), 0);
+
+  return histogram->priv->n_bins;
+}
+
+gboolean
+gimp_histogram_has_channel (GimpHistogram        *histogram,
+                            GimpHistogramChannel  channel)
+{
+  g_return_val_if_fail (GIMP_IS_HISTOGRAM (histogram), FALSE);
+
+  switch (channel)
+    {
+    case GIMP_HISTOGRAM_VALUE:
+      return TRUE;
+
+    case GIMP_HISTOGRAM_RED:
+    case GIMP_HISTOGRAM_GREEN:
+    case GIMP_HISTOGRAM_BLUE:
+    case GIMP_HISTOGRAM_LUMINANCE:
+    case GIMP_HISTOGRAM_RGB:
+      return gimp_histogram_n_components (histogram) >= 3;
+
+    case GIMP_HISTOGRAM_ALPHA:
+      return gimp_histogram_n_components (histogram) == 2 ||
+             gimp_histogram_n_components (histogram) == 4;
+    }
+
+  g_return_val_if_reached (FALSE);
+}
+
+gdouble
+gimp_histogram_get_count (GimpHistogram        *histogram,
+                          GimpHistogramChannel  channel,
+                          gint                  start,
+                          gint                  end)
+{
+  GimpHistogramPrivate *priv;
+  gint                  i;
+  gdouble               count = 0.0;
+
+  g_return_val_if_fail (GIMP_IS_HISTOGRAM (histogram), 0.0);
+
+  priv = histogram->priv;
+
+  if (! priv->values ||
+      start > end    ||
+      ! gimp_histogram_map_channel (histogram, &channel))
+    {
+      return 0.0;
+    }
+
+  if (channel == GIMP_HISTOGRAM_RGB)
+    return (gimp_histogram_get_count (histogram,
+                                      GIMP_HISTOGRAM_RED, start, end)   +
+            gimp_histogram_get_count (histogram,
+                                      GIMP_HISTOGRAM_GREEN, start, end) +
+            gimp_histogram_get_count (histogram,
+                                      GIMP_HISTOGRAM_BLUE, start, end));
+
+  start = CLAMP (start, 0, priv->n_bins - 1);
+  end   = CLAMP (end,   0, priv->n_bins - 1);
+
+  for (i = start; i <= end; i++)
+    count += HISTOGRAM_VALUE (channel, i);
+
+  return count;
+}
+
+gdouble
+gimp_histogram_get_mean (GimpHistogram        *histogram,
+                         GimpHistogramChannel  channel,
+                         gint                  start,
+                         gint                  end)
+{
+  GimpHistogramPrivate *priv;
+  gint                  i;
+  gdouble               mean = 0.0;
+  gdouble               count;
+
+  g_return_val_if_fail (GIMP_IS_HISTOGRAM (histogram), 0.0);
+
+  priv = histogram->priv;
+
+  if (! priv->values ||
+      start > end    ||
+      ! gimp_histogram_map_channel (histogram, &channel))
+    {
+      return 0.0;
+    }
+
+  start = CLAMP (start, 0, priv->n_bins - 1);
+  end   = CLAMP (end,   0, priv->n_bins - 1);
+
+  if (channel == GIMP_HISTOGRAM_RGB)
+    {
+      for (i = start; i <= end; i++)
+        {
+          gdouble factor = (gdouble) i / (gdouble)  (priv->n_bins - 1);
+
+          mean += (factor * HISTOGRAM_VALUE (GIMP_HISTOGRAM_RED,   i) +
+                   factor * HISTOGRAM_VALUE (GIMP_HISTOGRAM_GREEN, i) +
+                   factor * HISTOGRAM_VALUE (GIMP_HISTOGRAM_BLUE,  i));
+        }
+    }
+  else
+    {
+      for (i = start; i <= end; i++)
+        {
+          gdouble factor = (gdouble) i / (gdouble)  (priv->n_bins - 1);
+
+          mean += factor * HISTOGRAM_VALUE (channel, i);
+        }
+    }
+
+  count = gimp_histogram_get_count (histogram, channel, start, end);
+
+  if (count > 0.0)
+    return mean / count;
+
+  return mean;
+}
+
+gdouble
+gimp_histogram_get_median (GimpHistogram         *histogram,
+                           GimpHistogramChannel   channel,
+                           gint                   start,
+                           gint                   end)
+{
+  GimpHistogramPrivate *priv;
+  gint                  i;
+  gdouble               sum = 0.0;
+  gdouble               count;
+
+  g_return_val_if_fail (GIMP_IS_HISTOGRAM (histogram), -1.0);
+
+  priv = histogram->priv;
+
+  if (! priv->values ||
+      start > end    ||
+      ! gimp_histogram_map_channel (histogram, &channel))
+    {
+      return 0.0;
+    }
+
+  start = CLAMP (start, 0, priv->n_bins - 1);
+  end   = CLAMP (end,   0, priv->n_bins - 1);
+
+  count = gimp_histogram_get_count (histogram, channel, start, end);
+
+  if (channel == GIMP_HISTOGRAM_RGB)
+    {
+      for (i = start; i <= end; i++)
+        {
+          sum += (HISTOGRAM_VALUE (GIMP_HISTOGRAM_RED,   i) +
+                  HISTOGRAM_VALUE (GIMP_HISTOGRAM_GREEN, i) +
+                  HISTOGRAM_VALUE (GIMP_HISTOGRAM_BLUE,  i));
+
+          if (sum * 2 > count)
+            return ((gdouble) i / (gdouble)  (priv->n_bins - 1));
+        }
+    }
+  else
+    {
+      for (i = start; i <= end; i++)
+        {
+          sum += HISTOGRAM_VALUE (channel, i);
+
+          if (sum * 2 > count)
+            return ((gdouble) i / (gdouble)  (priv->n_bins - 1));
+        }
+    }
+
+  return -1.0;
+}
+
+/*
+ * adapted from GNU ocrad 0.14 : page_image_io.cc : otsu_th
+ *
+ *  N. Otsu, "A threshold selection method from gray-level histograms,"
+ *  IEEE Trans. Systems, Man, and Cybernetics, vol. 9, no. 1, pp. 62-66, 1979.
+ */
+gdouble
+gimp_histogram_get_threshold (GimpHistogram        *histogram,
+                              GimpHistogramChannel  channel,
+                              gint                  start,
+                              gint                  end)
+{
+  GimpHistogramPrivate *priv;
+  gint                 i;
+  gint                 maxval;
+  gdouble             *hist      = NULL;
+  gdouble             *chist     = NULL;
+  gdouble             *cmom      = NULL;
+  gdouble              hist_max  = 0.0;
+  gdouble              chist_max = 0.0;
+  gdouble              cmom_max  = 0.0;
+  gdouble              bvar_max  = 0.0;
+  gint                 threshold = 127;
+
+  g_return_val_if_fail (GIMP_IS_HISTOGRAM (histogram), -1);
+
+  priv = histogram->priv;
+
+  if (! priv->values ||
+      start > end    ||
+      ! gimp_histogram_map_channel (histogram, &channel))
+    {
+      return 0;
+    }
+
+  start = CLAMP (start, 0, priv->n_bins - 1);
+  end   = CLAMP (end,   0, priv->n_bins - 1);
+
+  maxval = end - start;
+
+  hist  = g_newa (gdouble, maxval + 1);
+  chist = g_newa (gdouble, maxval + 1);
+  cmom  = g_newa (gdouble, maxval + 1);
+
+  if (channel == GIMP_HISTOGRAM_RGB)
+    {
+      for (i = start; i <= end; i++)
+        hist[i - start] = (HISTOGRAM_VALUE (GIMP_HISTOGRAM_RED,   i) +
+                           HISTOGRAM_VALUE (GIMP_HISTOGRAM_GREEN, i) +
+                           HISTOGRAM_VALUE (GIMP_HISTOGRAM_BLUE,  i));
+    }
+  else
+    {
+      for (i = start; i <= end; i++)
+        hist[i - start] = HISTOGRAM_VALUE (channel, i);
+    }
+
+  hist_max = hist[0];
+  chist[0] = hist[0];
+  cmom[0] = 0;
+
+  for (i = 1; i <= maxval; i++)
+    {
+      if (hist[i] > hist_max)
+        hist_max = hist[i];
+
+      chist[i] = chist[i-1] + hist[i];
+      cmom[i] = cmom[i-1] + i * hist[i];
+    }
+
+  chist_max = chist[maxval];
+  cmom_max = cmom[maxval];
+  bvar_max = 0;
+
+  for (i = 0; i < maxval; ++i)
+    {
+      if (chist[i] > 0 && chist[i] < chist_max)
+        {
+          gdouble bvar;
+
+          bvar = (gdouble) cmom[i] / chist[i];
+          bvar -= (cmom_max - cmom[i]) / (chist_max - chist[i]);
+          bvar *= bvar;
+          bvar *= chist[i];
+          bvar *= chist_max - chist[i];
+
+          if (bvar > bvar_max)
+            {
+              bvar_max = bvar;
+              threshold = start + i;
+            }
+        }
+    }
+
+  return threshold;
+}
+
+gdouble
+gimp_histogram_get_std_dev (GimpHistogram        *histogram,
+                            GimpHistogramChannel  channel,
+                            gint                  start,
+                            gint                  end)
+{
+  GimpHistogramPrivate *priv;
+  gint                  i;
+  gdouble               dev = 0.0;
+  gdouble               count;
+  gdouble               mean;
+
+  g_return_val_if_fail (GIMP_IS_HISTOGRAM (histogram), 0.0);
+
+  priv = histogram->priv;
+
+  if (! priv->values ||
+      start > end    ||
+      ! gimp_histogram_map_channel (histogram, &channel))
+    {
+      return 0.0;
+    }
+
+  mean  = gimp_histogram_get_mean  (histogram, channel, start, end);
+  count = gimp_histogram_get_count (histogram, channel, start, end);
+
+  if (count == 0.0)
+    count = 1.0;
+
+  for (i = start; i <= end; i++)
+    {
+      gdouble value;
+
+      if (channel == GIMP_HISTOGRAM_RGB)
+        {
+          value = (HISTOGRAM_VALUE (GIMP_HISTOGRAM_RED,   i) +
+                   HISTOGRAM_VALUE (GIMP_HISTOGRAM_GREEN, i) +
+                   HISTOGRAM_VALUE (GIMP_HISTOGRAM_BLUE,  i));
+        }
+      else
+        {
+          value = gimp_histogram_get_value (histogram, channel, i);
+        }
+
+      dev += value * SQR (((gdouble) i / (gdouble)  (priv->n_bins - 1)) - mean);
+    }
+
+  return sqrt (dev / count);
+}
+
+
+/*  private functions  */
+
+static gboolean
+gimp_histogram_map_channel (GimpHistogram        *histogram,
+                            GimpHistogramChannel *channel)
+{
+  GimpHistogramPrivate *priv = histogram->priv;
+
+  if (*channel == GIMP_HISTOGRAM_RGB)
+    return gimp_histogram_n_components (histogram) >= 3;
+
+  switch (*channel)
+    {
+    case GIMP_HISTOGRAM_ALPHA:
+      if (gimp_histogram_n_components (histogram) == 2)
+        *channel = 1;
+      break;
+
+    case GIMP_HISTOGRAM_LUMINANCE:
+      *channel = gimp_histogram_n_components (histogram) + 1;
+      break;
+
+    default:
+      break;
+    }
+
+  return *channel < priv->n_channels;
+}
+
+static void
+gimp_histogram_set_values (GimpHistogram *histogram,
+                           gint           n_components,
+                           gint           n_bins,
+                           gdouble       *values)
+{
+  GimpHistogramPrivate *priv                = histogram->priv;
+  gint                  n_channels          = n_components;
+  gboolean              notify_n_components = FALSE;
+  gboolean              notify_n_bins       = FALSE;
+
+  if (n_channels > 0)
+    n_channels += N_DERIVED_CHANNELS;
+
+  if (n_channels != priv->n_channels)
+    {
+      priv->n_channels = n_channels;
+
+      notify_n_components = TRUE;
+    }
+
+  if (n_bins != priv->n_bins)
+    {
+      priv->n_bins = n_bins;
+
+      notify_n_bins = TRUE;
+    }
+
+  if (values != priv->values)
+    {
+      if (priv->values)
+        g_free (priv->values);
+
+      priv->values = values;
+    }
+
+  if (notify_n_components)
+    g_object_notify (G_OBJECT (histogram), "n-components");
+
+  if (notify_n_bins)
+    g_object_notify (G_OBJECT (histogram), "n-bins");
+
+  g_object_notify (G_OBJECT (histogram), "values");
+}
+
+static void
+gimp_histogram_calculate_internal (GimpAsync        *async,
+                                   CalculateContext *context)
+{
+  CalculateData         data;
+  GimpHistogramPrivate *priv;
+  const Babl           *format;
+
+  priv = context->histogram->priv;
+
+  format = gegl_buffer_get_format (context->buffer);
+
+  if (babl_format_get_type (format, 0) == babl_type ("u8"))
+    context->n_bins = 256;
+  else
+    context->n_bins = 1024;
+
+  if (babl_format_is_palette (format))
+    {
+      if (babl_format_has_alpha (format))
+        {
+          if (priv->linear)
+            format = babl_format ("RGB float");
+          else
+            format = babl_format ("R'G'B' float");
+        }
+      else
+        {
+          if (priv->linear)
+            format = babl_format ("RGBA float");
+          else
+            format = babl_format ("R'G'B'A float");
+        }
+    }
+  else
+    {
+      const Babl *model = babl_format_get_model (format);
+
+      if (model == babl_model ("Y") ||
+          model == babl_model ("Y'"))
+        {
+          if (priv->linear)
+            format = babl_format ("Y float");
+          else
+            format = babl_format ("Y' float");
+        }
+      else if (model == babl_model ("YA") ||
+               model == babl_model ("Y'A"))
+        {
+          if (priv->linear)
+            format = babl_format ("YA float");
+          else
+            format = babl_format ("Y'A float");
+        }
+      else if (model == babl_model ("RGB") ||
+               model == babl_model ("R'G'B'"))
+        {
+          if (priv->linear)
+            format = babl_format ("RGB float");
+          else
+            format = babl_format ("R'G'B' float");
+        }
+      else if (model == babl_model ("RGBA") ||
+               model == babl_model ("R'G'B'A"))
+        {
+          if (priv->linear)
+            format = babl_format ("RGBA float");
+          else
+            format = babl_format ("R'G'B'A float");
+        }
+      else
+        {
+          if (async)
+            gimp_async_abort (async);
+
+          g_return_if_reached ();
+        }
+    }
+
+  context->n_components = babl_format_get_n_components (format);
+
+  data.async       = async;
+  data.context     = context;
+  data.format      = format;
+  data.values_list = NULL;
+
+  gegl_parallel_distribute_area (
+    &context->buffer_rect, PIXELS_PER_THREAD, GEGL_SPLIT_STRATEGY_AUTO,
+    (GeglParallelDistributeAreaFunc) gimp_histogram_calculate_area,
+    &data);
+
+  if (! async || ! gimp_async_is_canceled (async))
+    {
+      gdouble *total_values = NULL;
+      gint     n_values     = (context->n_components + N_DERIVED_CHANNELS) *
+                              context->n_bins;
+      GSList  *iter;
+
+      for (iter = data.values_list; iter; iter = g_slist_next (iter))
+        {
+          gdouble *values = iter->data;
+
+          if (! total_values)
+            {
+              total_values = values;
+            }
+          else
+            {
+              gint i;
+
+              for (i = 0; i < n_values; i++)
+                total_values[i] += values[i];
+
+              g_free (values);
+            }
+        }
+
+      g_slist_free (data.values_list);
+
+      context->values = total_values;
+
+      if (async)
+        gimp_async_finish (async, NULL);
+    }
+  else
+    {
+      g_slist_free_full (data.values_list, g_free);
+
+      if (async)
+        gimp_async_abort (async);
+    }
+}
+
+static void
+gimp_histogram_calculate_area (const GeglRectangle *area,
+                               CalculateData       *data)
+{
+  GimpAsync            *async;
+  CalculateContext     *context;
+  GeglBufferIterator   *iter;
+  gdouble              *values;
+  gint                  n_components;
+  gint                  n_bins;
+  gfloat                n_bins_1f;
+  gfloat                temp;
+
+  async   = data->async;
+  context = data->context;
+
+  n_bins       = context->n_bins;
+  n_components = context->n_components;
+
+  values = g_new0 (gdouble, (n_components + N_DERIVED_CHANNELS) * n_bins);
+  gimp_atomic_slist_push_head (&data->values_list, values);
+
+  iter = gegl_buffer_iterator_new (context->buffer, area, 0,
+                                   data->format,
+                                   GEGL_ACCESS_READ, GEGL_ABYSS_NONE, 2);
+
+  if (context->mask)
+    {
+      GeglRectangle mask_area = *area;
+
+      mask_area.x += context->mask_rect.x - context->buffer_rect.x;
+      mask_area.y += context->mask_rect.y - context->buffer_rect.y;
+
+      gegl_buffer_iterator_add (iter, context->mask, &mask_area, 0,
+                                babl_format ("Y float"),
+                                GEGL_ACCESS_READ, GEGL_ABYSS_NONE);
+    }
+
+  n_bins_1f = n_bins - 1;
+
+#define VALUE(c,i) (*(temp = (i) * n_bins_1f,                                  \
+                      &values[(c) * n_bins +                                   \
+                              SIGNED_ROUND (SAFE_CLAMP (temp,                  \
+                                                        0.0f,                  \
+                                                        n_bins_1f))]))
+
+#define CHECK_CANCELED(length)                                                 \
+  G_STMT_START                                                                 \
+    {                                                                          \
+      if ((length) % 128 == 0 && async && gimp_async_is_canceled (async))      \
+        {                                                                      \
+          gegl_buffer_iterator_stop (iter);                                    \
+                                                                               \
+          return;                                                              \
+        }                                                                      \
+    }                                                                          \
+  G_STMT_END
+
+  while (gegl_buffer_iterator_next (iter))
+    {
+      const gfloat *data   = iter->items[0].data;
+      gint          length = iter->length;
+      gfloat        max;
+      gfloat        luminance;
+
+      CHECK_CANCELED (0);
+
+      if (context->mask)
+        {
+          const gfloat *mask_data = iter->items[1].data;
+
+          switch (n_components)
+            {
+            case 1:
+              while (length--)
+                {
+                  const gdouble masked = *mask_data;
+
+                  VALUE (0, data[0]) += masked;
+
+                  data += n_components;
+                  mask_data += 1;
+
+                  CHECK_CANCELED (length);
+                }
+              break;
+
+            case 2:
+              while (length--)
+                {
+                  const gdouble masked = *mask_data;
+                  const gdouble weight = data[1];
+
+                  VALUE (0, data[0]) += weight * masked;
+                  VALUE (1, data[1]) += masked;
+
+                  data += n_components;
+                  mask_data += 1;
+
+                  CHECK_CANCELED (length);
+                }
+              break;
+
+            case 3: /* calculate separate value values */
+              while (length--)
+                {
+                  const gdouble masked = *mask_data;
+
+                  VALUE (1, data[0]) += masked;
+                  VALUE (2, data[1]) += masked;
+                  VALUE (3, data[2]) += masked;
+
+                  max = MAX (data[0], data[1]);
+                  max = MAX (data[2], max);
+                  VALUE (0, max) += masked;
+
+                  luminance = GIMP_RGB_LUMINANCE (data[0], data[1], data[2]);
+                  VALUE (4, luminance) += masked;
+
+                  data += n_components;
+                  mask_data += 1;
+
+                  CHECK_CANCELED (length);
+                }
+              break;
+
+            case 4: /* calculate separate value values */
+              while (length--)
+                {
+                  const gdouble masked = *mask_data;
+                  const gdouble weight = data[3];
+
+                  VALUE (1, data[0]) += weight * masked;
+                  VALUE (2, data[1]) += weight * masked;
+                  VALUE (3, data[2]) += weight * masked;
+                  VALUE (4, data[3]) += masked;
+
+                  max = MAX (data[0], data[1]);
+                  max = MAX (data[2], max);
+                  VALUE (0, max) += weight * masked;
+
+                  luminance = GIMP_RGB_LUMINANCE (data[0], data[1], data[2]);
+                  VALUE (5, luminance) += weight * masked;
+
+                  data += n_components;
+                  mask_data += 1;
+
+                  CHECK_CANCELED (length);
+                }
+              break;
+            }
+        }
+      else /* no mask */
+        {
+          switch (n_components)
+            {
+            case 1:
+              while (length--)
+                {
+                  VALUE (0, data[0]) += 1.0;
+
+                  data += n_components;
+
+                  CHECK_CANCELED (length);
+                }
+              break;
+
+            case 2:
+              while (length--)
+                {
+                  const gdouble weight = data[1];
+
+                  VALUE (0, data[0]) += weight;
+                  VALUE (1, data[1]) += 1.0;
+
+                  data += n_components;
+
+                  CHECK_CANCELED (length);
+                }
+              break;
+
+            case 3: /* calculate separate value values */
+              while (length--)
+                {
+                  VALUE (1, data[0]) += 1.0;
+                  VALUE (2, data[1]) += 1.0;
+                  VALUE (3, data[2]) += 1.0;
+
+                  max = MAX (data[0], data[1]);
+                  max = MAX (data[2], max);
+                  VALUE (0, max) += 1.0;
+
+                  luminance = GIMP_RGB_LUMINANCE (data[0], data[1], data[2]);
+                  VALUE (4, luminance) += 1.0;
+
+                  data += n_components;
+
+                  CHECK_CANCELED (length);
+                }
+              break;
+
+            case 4: /* calculate separate value values */
+              while (length--)
+                {
+                  const gdouble weight = data[3];
+
+                  VALUE (1, data[0]) += weight;
+                  VALUE (2, data[1]) += weight;
+                  VALUE (3, data[2]) += weight;
+                  VALUE (4, data[3]) += 1.0;
+
+                  max = MAX (data[0], data[1]);
+                  max = MAX (data[2], max);
+                  VALUE (0, max) += weight;
+
+                  luminance = GIMP_RGB_LUMINANCE (data[0], data[1], data[2]);
+                  VALUE (5, luminance) += weight;
+
+                  data += n_components;
+
+                  CHECK_CANCELED (length);
+                }
+              break;
+            }
+        }
+    }
+
+#undef VALUE
+#undef CHECK_CANCELED
+}
+
+static void
+gimp_histogram_calculate_async_callback (GimpAsync        *async,
+                                         CalculateContext *context)
+{
+  context->histogram->priv->calculate_async = NULL;
+
+  if (gimp_async_is_finished (async))
+    {
+      gimp_histogram_set_values (context->histogram,
+                                 context->n_components, context->n_bins,
+                                 context->values);
+    }
+
+  g_object_unref (context->buffer);
+  if (context->mask)
+    g_object_unref (context->mask);
+
+  g_slice_free (CalculateContext, context);
+}
diff --git a/app/core/gimphistogram.h b/app/core/gimphistogram.h
new file mode 100644
index 0000000..ba1e0ef
--- /dev/null
+++ b/app/core/gimphistogram.h
@@ -0,0 +1,105 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimphistogram module Copyright (C) 1999 Jay Cox <jaycox@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_HISTOGRAM_H__
+#define __GIMP_HISTOGRAM_H__
+
+
+#include "gimpobject.h"
+
+
+#define GIMP_TYPE_HISTOGRAM            (gimp_histogram_get_type ())
+#define GIMP_HISTOGRAM(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_HISTOGRAM, GimpHistogram))
+#define GIMP_HISTOGRAM_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_HISTOGRAM, GimpHistogramClass))
+#define GIMP_IS_HISTOGRAM(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_HISTOGRAM))
+#define GIMP_IS_HISTOGRAM_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_HISTOGRAM))
+#define GIMP_HISTOGRAM_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_HISTOGRAM, GimpHistogramClass))
+
+
+typedef struct _GimpHistogramPrivate GimpHistogramPrivate;
+typedef struct _GimpHistogramClass   GimpHistogramClass;
+
+struct _GimpHistogram
+{
+  GimpObject            parent_instance;
+
+  GimpHistogramPrivate *priv;
+};
+
+struct _GimpHistogramClass
+{
+  GimpObjectClass  parent_class;
+};
+
+
+GType           gimp_histogram_get_type        (void) G_GNUC_CONST;
+
+GimpHistogram * gimp_histogram_new             (gboolean              linear);
+
+GimpHistogram * gimp_histogram_duplicate       (GimpHistogram        *histogram);
+
+void            gimp_histogram_calculate       (GimpHistogram        *histogram,
+                                                GeglBuffer           *buffer,
+                                                const GeglRectangle  *buffer_rect,
+                                                GeglBuffer           *mask,
+                                                const GeglRectangle  *mask_rect);
+GimpAsync     * gimp_histogram_calculate_async (GimpHistogram        *histogram,
+                                                GeglBuffer           *buffer,
+                                                const GeglRectangle  *buffer_rect,
+                                                GeglBuffer           *mask,
+                                                const GeglRectangle  *mask_rect);
+
+void            gimp_histogram_clear_values    (GimpHistogram        *histogram,
+                                                gint                  n_components);
+
+gdouble         gimp_histogram_get_maximum     (GimpHistogram        *histogram,
+                                                GimpHistogramChannel  channel);
+gdouble         gimp_histogram_get_count       (GimpHistogram        *histogram,
+                                                GimpHistogramChannel  channel,
+                                                gint                  start,
+                                                gint                  end);
+gdouble         gimp_histogram_get_mean        (GimpHistogram        *histogram,
+                                                GimpHistogramChannel  channel,
+                                                gint                  start,
+                                                gint                  end);
+gdouble         gimp_histogram_get_median      (GimpHistogram        *histogram,
+                                                GimpHistogramChannel  channel,
+                                                gint                  start,
+                                                gint                  end);
+gdouble         gimp_histogram_get_std_dev     (GimpHistogram        *histogram,
+                                                GimpHistogramChannel  channel,
+                                                gint                  start,
+                                                gint                  end);
+gdouble         gimp_histogram_get_threshold   (GimpHistogram        *histogram,
+                                                GimpHistogramChannel  channel,
+                                                gint                  start,
+                                                gint                  end);
+gdouble         gimp_histogram_get_value       (GimpHistogram        *histogram,
+                                                GimpHistogramChannel  channel,
+                                                gint                  bin);
+gdouble         gimp_histogram_get_component   (GimpHistogram        *histogram,
+                                                gint                  component,
+                                                gint                  bin);
+gint            gimp_histogram_n_components    (GimpHistogram        *histogram);
+gint            gimp_histogram_n_bins          (GimpHistogram        *histogram);
+gboolean        gimp_histogram_has_channel     (GimpHistogram        *histogram,
+                                                GimpHistogramChannel  channel);
+
+
+#endif /* __GIMP_HISTOGRAM_H__ */
diff --git a/app/core/gimpidtable.c b/app/core/gimpidtable.c
new file mode 100644
index 0000000..b69a13d
--- /dev/null
+++ b/app/core/gimpidtable.c
@@ -0,0 +1,227 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpidtable.c
+ * Copyright (C) 2011 Martin Nordholts <martinn@src.gnome.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gio/gio.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gimp-memsize.h"
+#include "gimpidtable.h"
+
+
+#define GIMP_ID_TABLE_START_ID 1
+#define GIMP_ID_TABLE_END_ID   G_MAXINT
+
+
+struct _GimpIdTablePrivate
+{
+  GHashTable *id_table;
+  gint        next_id;
+};
+
+
+static void    gimp_id_table_finalize    (GObject    *object);
+static gint64  gimp_id_table_get_memsize (GimpObject *object,
+                                          gint64     *gui_size);
+
+
+G_DEFINE_TYPE_WITH_PRIVATE (GimpIdTable, gimp_id_table, GIMP_TYPE_OBJECT)
+
+#define parent_class gimp_id_table_parent_class
+
+
+static void
+gimp_id_table_class_init (GimpIdTableClass *klass)
+{
+  GObjectClass    *object_class      = G_OBJECT_CLASS (klass);
+  GimpObjectClass *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+
+  object_class->finalize         = gimp_id_table_finalize;
+
+  gimp_object_class->get_memsize = gimp_id_table_get_memsize;
+}
+
+static void
+gimp_id_table_init (GimpIdTable *id_table)
+{
+  id_table->priv = gimp_id_table_get_instance_private (id_table);
+
+  id_table->priv->id_table = g_hash_table_new (g_direct_hash, NULL);
+  id_table->priv->next_id  = GIMP_ID_TABLE_START_ID;
+}
+
+static void
+gimp_id_table_finalize (GObject *object)
+{
+  GimpIdTable *id_table = GIMP_ID_TABLE (object);
+
+  g_clear_pointer (&id_table->priv->id_table, g_hash_table_unref);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static gint64
+gimp_id_table_get_memsize (GimpObject *object,
+                           gint64     *gui_size)
+{
+  GimpIdTable *id_table = GIMP_ID_TABLE (object);
+  gint64       memsize  = 0;
+
+  memsize += gimp_g_hash_table_get_memsize (id_table->priv->id_table, 0);
+
+  return memsize + GIMP_OBJECT_CLASS (parent_class)->get_memsize (object,
+                                                                  gui_size);
+}
+
+/**
+ * gimp_id_table_new:
+ *
+ * Returns: A new #GimpIdTable.
+ **/
+GimpIdTable *
+gimp_id_table_new (void)
+{
+  return g_object_new (GIMP_TYPE_ID_TABLE, NULL);
+}
+
+/**
+ * gimp_id_table_insert:
+ * @id_table: A #GimpIdTable
+ * @data: Data to insert and assign an id to
+ *
+ * Insert data in the id table. The data will get an, in this table,
+ * unused ID assigned to it that can be used to later lookup the data.
+ *
+ * Returns: The assigned ID.
+ **/
+gint
+gimp_id_table_insert (GimpIdTable *id_table, gpointer data)
+{
+  gint new_id;
+  gint start_id;
+
+  g_return_val_if_fail (GIMP_IS_ID_TABLE (id_table), 0);
+
+  start_id = id_table->priv->next_id;
+
+  do
+    {
+      new_id = id_table->priv->next_id++;
+
+      if (id_table->priv->next_id == GIMP_ID_TABLE_END_ID)
+        id_table->priv->next_id = GIMP_ID_TABLE_START_ID;
+
+      if (start_id == id_table->priv->next_id)
+        {
+          /* We looped once over all used ids. Very unlikely to happen.
+             And if it does, there is probably not much to be done.
+             It is just good design not to allow a theoretical infinite loop. */
+          g_error ("%s: out of ids!", G_STRFUNC);
+          break;
+        }
+    }
+  while (gimp_id_table_lookup (id_table, new_id));
+
+  return gimp_id_table_insert_with_id (id_table, new_id, data);
+}
+
+/**
+ * gimp_id_table_insert_with_id:
+ * @id_table: An #GimpIdTable
+ * @id: The ID to use. Must be greater than 0.
+ * @data: The data to associate with the id
+ *
+ * Insert data in the id table with a specific ID. If data already
+ * exsts with the given ID, this function fails.
+ *
+ * Returns: The used ID if successful, -1 if it was already in use.
+ **/
+gint
+gimp_id_table_insert_with_id (GimpIdTable *id_table, gint id, gpointer data)
+{
+  g_return_val_if_fail (GIMP_IS_ID_TABLE (id_table), 0);
+  g_return_val_if_fail (id > 0, 0);
+
+  if (gimp_id_table_lookup (id_table, id))
+    return -1;
+
+  g_hash_table_insert (id_table->priv->id_table, GINT_TO_POINTER (id), data);
+
+  return id;
+}
+
+/**
+ * gimp_id_table_replace:
+ * @id_table: An #GimpIdTable
+ * @id: The ID to use. Must be greater than 0.
+ * @data: The data to insert/replace
+ *
+ * Replaces (if an item with the given ID exists) or inserts a new
+ * entry in the id table.
+ **/
+void
+gimp_id_table_replace (GimpIdTable *id_table, gint id, gpointer data)
+{
+  g_return_if_fail (GIMP_IS_ID_TABLE (id_table));
+  g_return_if_fail (id > 0);
+
+  g_hash_table_replace (id_table->priv->id_table, GINT_TO_POINTER (id), data);
+}
+
+/**
+ * gimp_id_table_lookup:
+ * @id_table: An #GimpIdTable
+ * @id: The ID of the data to lookup
+ *
+ * Lookup data based on ID.
+ *
+ * Returns: The data, or NULL if no data with the given ID was found.
+ **/
+gpointer
+gimp_id_table_lookup (GimpIdTable *id_table, gint id)
+{
+  g_return_val_if_fail (GIMP_IS_ID_TABLE (id_table), NULL);
+
+  return g_hash_table_lookup (id_table->priv->id_table, GINT_TO_POINTER (id));
+}
+
+
+/**
+ * gimp_id_table_remove:
+ * @id_table: An #GimpIdTable
+ * @id: The ID of the data to remove.
+ *
+ * Remove the data from the table with the given ID.
+ *
+ * Returns: %TRUE if data with the ID existed and was successfully
+ *          removed, %FALSE otherwise.
+ **/
+gboolean
+gimp_id_table_remove (GimpIdTable *id_table, gint id)
+{
+  g_return_val_if_fail (GIMP_IS_ID_TABLE (id_table), FALSE);
+
+  g_return_val_if_fail (id_table != NULL, FALSE);
+
+  return g_hash_table_remove (id_table->priv->id_table, GINT_TO_POINTER (id));
+}
diff --git a/app/core/gimpidtable.h b/app/core/gimpidtable.h
new file mode 100644
index 0000000..88097fd
--- /dev/null
+++ b/app/core/gimpidtable.h
@@ -0,0 +1,68 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpidtable.h
+ * Copyright (C) 2011 Martin Nordholts <martinn@src.gnome.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_ID_TABLE_H__
+#define __GIMP_ID_TABLE_H__
+
+
+#include "gimpobject.h"
+
+
+#define GIMP_TYPE_ID_TABLE            (gimp_id_table_get_type ())
+#define GIMP_ID_TABLE(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_ID_TABLE, GimpIdTable))
+#define GIMP_ID_TABLE_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_ID_TABLE, GimpIdTableClass))
+#define GIMP_IS_ID_TABLE(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_ID_TABLE))
+#define GIMP_IS_ID_TABLE_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_ID_TABLE))
+#define GIMP_ID_TABLE_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_ID_TABLE, GimpIdTableClass))
+
+
+typedef struct _GimpIdTableClass   GimpIdTableClass;
+typedef struct _GimpIdTablePrivate GimpIdTablePrivate;
+
+struct _GimpIdTable
+{
+  GimpObject          parent_instance;
+
+  GimpIdTablePrivate *priv;
+};
+
+struct _GimpIdTableClass
+{
+  GimpObjectClass  parent_class;
+};
+
+
+GType          gimp_id_table_get_type       (void) G_GNUC_CONST;
+GimpIdTable *  gimp_id_table_new            (void);
+gint           gimp_id_table_insert         (GimpIdTable *id_table,
+                                             gpointer     data);
+gint           gimp_id_table_insert_with_id (GimpIdTable *id_table,
+                                             gint         id,
+                                             gpointer     data);
+void           gimp_id_table_replace        (GimpIdTable *id_table,
+                                             gint         id,
+                                             gpointer     data);
+gpointer       gimp_id_table_lookup         (GimpIdTable *id_table,
+                                             gint         id);
+gboolean       gimp_id_table_remove         (GimpIdTable *id_table,
+                                             gint         id);
+
+
+#endif  /*  __GIMP_ID_TABLE_H__  */
diff --git a/app/core/gimpimage-arrange.c b/app/core/gimpimage-arrange.c
new file mode 100644
index 0000000..6b6b05e
--- /dev/null
+++ b/app/core/gimpimage-arrange.c
@@ -0,0 +1,388 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpmath/gimpmath.h"
+
+#include "core-types.h"
+
+#include "gimpimage.h"
+#include "gimpimage-arrange.h"
+#include "gimpimage-guides.h"
+#include "gimpimage-undo.h"
+#include "gimpitem.h"
+#include "gimpguide.h"
+
+#include "gimp-intl.h"
+
+
+static GList * sort_by_offset  (GList             *list);
+static void    compute_offsets (GList             *list,
+                                GimpAlignmentType  alignment);
+static void    compute_offset  (GObject           *object,
+                                GimpAlignmentType  alignment);
+static gint    offset_compare  (gconstpointer      a,
+                                gconstpointer      b);
+
+
+/**
+ * gimp_image_arrange_objects:
+ * @image:                The #GimpImage to which the objects belong.
+ * @list:                 A #GList of objects to be aligned.
+ * @alignment:            The point on each target object to bring into alignment.
+ * @reference:            The #GObject to align the targets with, or #NULL.
+ * @reference_alignment:  The point on the reference object to align the target item with..
+ * @offset:               How much to shift the target from perfect alignment..
+ *
+ * This function shifts the positions of a set of target objects,
+ * which can be "items" or guides, to bring them into a specified type
+ * of alignment with a reference object, which can be an item, guide,
+ * or image.  If the requested alignment does not make sense (i.e.,
+ * trying to align a vertical guide vertically), nothing happens and
+ * no error message is generated.
+ *
+ * The objects in the list are sorted into increasing order before
+ * being arranged, where the order is defined by the type of alignment
+ * being requested.  If the @reference argument is #NULL, then the
+ * first object in the sorted list is used as reference.
+ *
+ * When there are multiple target objects, they are arranged so that
+ * the spacing between consecutive ones is given by the argument
+ * @offset but for HFILL and VFILL - in this case, @offset works as an
+ * internal margin for the distribution (and it can be negative).
+ */
+void
+gimp_image_arrange_objects (GimpImage         *image,
+                            GList             *list,
+                            GimpAlignmentType  alignment,
+                            GObject           *reference,
+                            GimpAlignmentType  reference_alignment,
+                            gint               offset)
+{
+  gboolean do_x = FALSE;
+  gboolean do_y = FALSE;
+  gint     z0   = 0;
+  GList   *object_list;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (G_IS_OBJECT (reference) || reference == NULL);
+
+  /* get offsets used for sorting */
+  switch (alignment)
+    {
+      /* order vertically for horizontal alignment */
+    case GIMP_ALIGN_LEFT:
+    case GIMP_ALIGN_HCENTER:
+    case GIMP_ALIGN_RIGHT:
+      do_x = TRUE;
+      compute_offsets (list, GIMP_ALIGN_TOP);
+      break;
+
+      /* order horizontally for horizontal arrangement */
+    case GIMP_ARRANGE_LEFT:
+    case GIMP_ARRANGE_HCENTER:
+    case GIMP_ARRANGE_RIGHT:
+    case GIMP_ARRANGE_HFILL:
+      do_x = TRUE;
+      compute_offsets (list, alignment);
+      break;
+
+      /* order horizontally for vertical alignment */
+    case GIMP_ALIGN_TOP:
+    case GIMP_ALIGN_VCENTER:
+    case GIMP_ALIGN_BOTTOM:
+      do_y = TRUE;
+      compute_offsets (list, GIMP_ALIGN_LEFT);
+      break;
+
+      /* order vertically for vertical arrangement */
+    case GIMP_ARRANGE_TOP:
+    case GIMP_ARRANGE_VCENTER:
+    case GIMP_ARRANGE_BOTTOM:
+    case GIMP_ARRANGE_VFILL:
+      do_y = TRUE;
+      compute_offsets (list, alignment);
+      break;
+
+    default:
+      g_return_if_reached ();
+    }
+
+  object_list = sort_by_offset (list);
+
+  /* now get offsets used for aligning */
+  compute_offsets (list, alignment);
+
+  if (reference == NULL)
+    {
+      reference = G_OBJECT (object_list->data);
+      object_list = g_list_next (object_list);
+      reference_alignment = alignment;
+    }
+  else
+    {
+      compute_offset (reference, reference_alignment);
+    }
+
+  z0 = GPOINTER_TO_INT (g_object_get_data (reference, "align-offset"));
+
+  if (object_list)
+    {
+      GList   *list;
+      gint     n;
+      gint     distr_width  = 0;
+      gint     distr_height = 0;
+      gdouble  fill_offset  = 0;
+
+      if (reference_alignment == GIMP_ARRANGE_HFILL)
+        {
+          distr_width = GPOINTER_TO_INT (g_object_get_data
+                                         (reference, "align-width"));
+          /* The offset parameter works as an internal margin */
+          fill_offset = (distr_width - 2 * offset) /
+                         (gint) g_list_length (object_list);
+        }
+      if (reference_alignment == GIMP_ARRANGE_VFILL)
+        {
+          distr_height = GPOINTER_TO_INT (g_object_get_data
+                                          (reference, "align-height"));
+          fill_offset = (distr_height - 2 * offset) /
+                         (gint) g_list_length (object_list);
+        }
+
+      /* FIXME: undo group type is wrong */
+      gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_ITEM_DISPLACE,
+                                   C_("undo-type", "Arrange Objects"));
+
+      for (list = object_list, n = 1;
+           list;
+           list = g_list_next (list), n++)
+        {
+          GObject *target     = list->data;
+          gint     xtranslate = 0;
+          gint     ytranslate = 0;
+          gint     z1;
+
+          z1 = GPOINTER_TO_INT (g_object_get_data (target, "align-offset"));
+
+          if (reference_alignment == GIMP_ARRANGE_HFILL)
+            {
+              gint width = GPOINTER_TO_INT (g_object_get_data (target,
+                                                               "align-width"));
+              xtranslate = ROUND (z0 - z1 + (n - 0.5) * fill_offset -
+                                  width / 2.0 + offset);
+            }
+          else if (reference_alignment == GIMP_ARRANGE_VFILL)
+            {
+              gint height = GPOINTER_TO_INT (g_object_get_data (target,
+                                                                "align-height"));
+              ytranslate =  ROUND (z0 - z1 + (n - 0.5) * fill_offset -
+                                   height / 2.0 + offset);
+            }
+          else /* the normal computing, when we don't depend on the
+                * width or height of the reference object
+                */
+            {
+              if (do_x)
+                xtranslate = z0 - z1 + n * offset;
+
+              if (do_y)
+                ytranslate = z0 - z1 + n * offset;
+            }
+
+          /* now actually align the target object */
+          if (GIMP_IS_ITEM (target))
+            {
+              gimp_item_translate (GIMP_ITEM (target),
+                                   xtranslate, ytranslate, TRUE);
+            }
+          else if (GIMP_IS_GUIDE (target))
+            {
+              GimpGuide *guide = GIMP_GUIDE (target);
+
+              switch (gimp_guide_get_orientation (guide))
+                {
+                case GIMP_ORIENTATION_VERTICAL:
+                  gimp_image_move_guide (image, guide, z1 + xtranslate, TRUE);
+                  break;
+
+                case GIMP_ORIENTATION_HORIZONTAL:
+                  gimp_image_move_guide (image, guide, z1 + ytranslate, TRUE);
+                  break;
+
+                default:
+                  break;
+                }
+            }
+        }
+
+      gimp_image_undo_group_end (image);
+    }
+
+  g_list_free (object_list);
+}
+
+static GList *
+sort_by_offset (GList *list)
+{
+  return g_list_sort (g_list_copy (list),
+                      offset_compare);
+
+}
+
+static gint
+offset_compare (gconstpointer a,
+                gconstpointer b)
+{
+  gint offset1 = GPOINTER_TO_INT (g_object_get_data (G_OBJECT (a),
+                                                     "align-offset"));
+  gint offset2 = GPOINTER_TO_INT (g_object_get_data (G_OBJECT (b),
+                                                     "align-offset"));
+
+  return offset1 - offset2;
+}
+
+/* this function computes the position of the alignment point
+ * for each object in the list, and attaches it to the
+ * object as object data.
+ */
+static void
+compute_offsets (GList             *list,
+                 GimpAlignmentType  alignment)
+{
+  GList *l;
+
+  for (l = list; l; l = g_list_next (l))
+    compute_offset (l->data, alignment);
+}
+
+static void
+compute_offset (GObject           *object,
+                GimpAlignmentType  alignment)
+{
+  gint object_offset_x = 0;
+  gint object_offset_y = 0;
+  gint object_height   = 0;
+  gint object_width    = 0;
+  gint offset          = 0;
+
+  if (GIMP_IS_IMAGE (object))
+    {
+      GimpImage *image = GIMP_IMAGE (object);
+
+      object_offset_x = 0;
+      object_offset_y = 0;
+      object_height   = gimp_image_get_height (image);
+      object_width    = gimp_image_get_width (image);
+    }
+  else if (GIMP_IS_ITEM (object))
+    {
+      GimpItem *item = GIMP_ITEM (object);
+      gint      off_x, off_y;
+
+      gimp_item_bounds (item,
+                        &object_offset_x,
+                        &object_offset_y,
+                        &object_width,
+                        &object_height);
+
+      gimp_item_get_offset (item, &off_x, &off_y);
+      object_offset_x += off_x;
+      object_offset_y += off_y;
+    }
+  else if (GIMP_IS_GUIDE (object))
+    {
+      GimpGuide *guide = GIMP_GUIDE (object);
+
+      switch (gimp_guide_get_orientation (guide))
+        {
+        case GIMP_ORIENTATION_VERTICAL:
+          object_offset_x = gimp_guide_get_position (guide);
+          object_width = 0;
+          break;
+
+        case GIMP_ORIENTATION_HORIZONTAL:
+          object_offset_y = gimp_guide_get_position (guide);
+          object_height = 0;
+          break;
+
+        default:
+          break;
+        }
+    }
+  else
+    {
+      g_printerr ("Alignment object is not an image, item or guide.\n");
+    }
+
+  switch (alignment)
+    {
+    case GIMP_ALIGN_LEFT:
+    case GIMP_ARRANGE_LEFT:
+    case GIMP_ARRANGE_HFILL:
+      offset = object_offset_x;
+      break;
+
+    case GIMP_ALIGN_HCENTER:
+    case GIMP_ARRANGE_HCENTER:
+      offset = object_offset_x + object_width / 2;
+      break;
+
+    case GIMP_ALIGN_RIGHT:
+    case GIMP_ARRANGE_RIGHT:
+      offset = object_offset_x + object_width;
+      break;
+
+    case GIMP_ALIGN_TOP:
+    case GIMP_ARRANGE_TOP:
+    case GIMP_ARRANGE_VFILL:
+      offset = object_offset_y;
+      break;
+
+    case GIMP_ALIGN_VCENTER:
+    case GIMP_ARRANGE_VCENTER:
+      offset = object_offset_y + object_height / 2;
+      break;
+
+    case GIMP_ALIGN_BOTTOM:
+    case GIMP_ARRANGE_BOTTOM:
+      offset = object_offset_y + object_height;
+      break;
+
+    default:
+      g_return_if_reached ();
+    }
+
+  g_object_set_data (object, "align-offset",
+                     GINT_TO_POINTER (offset));
+
+  /* These are only used for HFILL and VFILL, but since the call to
+   * gimp_image_arrange_objects allows for two different alignments
+   * (object and reference_alignment) we better be on the safe side in
+   * case they differ.  (the current implementation of the align tool
+   * always pass the same value to both parameters)
+   */
+  g_object_set_data (object, "align-width",
+                     GINT_TO_POINTER (object_width));
+
+  g_object_set_data (object, "align-height",
+                     GINT_TO_POINTER (object_height));
+}
diff --git a/app/core/gimpimage-arrange.h b/app/core/gimpimage-arrange.h
new file mode 100644
index 0000000..1109a5d
--- /dev/null
+++ b/app/core/gimpimage-arrange.h
@@ -0,0 +1,29 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_IMAGE_ARRANGE_H__
+#define __GIMP_IMAGE_ARRANGE_H__
+
+
+void gimp_image_arrange_objects (GimpImage         *image,
+                                 GList             *list,
+                                 GimpAlignmentType  alignment,
+                                 GObject           *reference,
+                                 GimpAlignmentType  reference_alignment,
+                                 gint               offset);
+
+#endif  /*  __GIMP_IMAGE_ARRANGE_H__  */
diff --git a/app/core/gimpimage-color-profile.c b/app/core/gimpimage-color-profile.c
new file mode 100644
index 0000000..a7030f3
--- /dev/null
+++ b/app/core/gimpimage-color-profile.c
@@ -0,0 +1,822 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpimage-color-profile.c
+ * Copyright (C) 2015 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <cairo.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpconfig/gimpconfig.h"
+#include "libgimpcolor/gimpcolor.h"
+#include "libgimpbase/gimpbase.h"
+
+#include "core-types.h"
+
+#include "config/gimpdialogconfig.h"
+
+#include "gegl/gimp-babl.h"
+#include "gegl/gimp-gegl-loops.h"
+
+#include "gimp.h"
+#include "gimpcontext.h"
+#include "gimpdrawable.h"
+#include "gimperror.h"
+#include "gimpimage.h"
+#include "gimpimage-color-profile.h"
+#include "gimpimage-colormap.h"
+#include "gimpimage-private.h"
+#include "gimpimage-undo.h"
+#include "gimpimage-undo-push.h"
+#include "gimpobjectqueue.h"
+#include "gimpprogress.h"
+
+#include "gimp-intl.h"
+
+
+/*  local function prototypes  */
+
+static void   gimp_image_convert_profile_layers   (GimpImage                *image,
+                                                   GimpColorProfile         *src_profile,
+                                                   GimpColorProfile         *dest_profile,
+                                                   GimpColorRenderingIntent  intent,
+                                                   gboolean                  bpc,
+                                                   GimpProgress             *progress);
+static void   gimp_image_convert_profile_colormap (GimpImage                *image,
+                                                   GimpColorProfile         *src_profile,
+                                                   GimpColorProfile         *dest_profile,
+                                                   GimpColorRenderingIntent  intent,
+                                                   gboolean                  bpc,
+                                                   GimpProgress             *progress);
+
+static void   gimp_image_create_color_transforms  (GimpImage                *image);
+
+
+/*  public functions  */
+
+gboolean
+gimp_image_get_is_color_managed (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->is_color_managed;
+}
+
+void
+gimp_image_set_is_color_managed (GimpImage *image,
+                                 gboolean   is_color_managed,
+                                 gboolean   push_undo)
+{
+  GimpImagePrivate *private;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  is_color_managed = is_color_managed ? TRUE : FALSE;
+
+  if (is_color_managed != private->is_color_managed)
+    {
+      if (push_undo)
+        gimp_image_undo_push_image_color_managed (image, NULL);
+
+      private->is_color_managed = is_color_managed;
+
+      gimp_color_managed_profile_changed (GIMP_COLOR_MANAGED (image));
+    }
+}
+
+gboolean
+gimp_image_validate_icc_parasite (GimpImage           *image,
+                                  const GimpParasite  *icc_parasite,
+                                  gboolean            *is_builtin,
+                                  GError             **error)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+  g_return_val_if_fail (icc_parasite != NULL, FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  if (strcmp (gimp_parasite_name (icc_parasite),
+              GIMP_ICC_PROFILE_PARASITE_NAME) != 0)
+    {
+      g_set_error_literal (error, GIMP_ERROR, GIMP_FAILED,
+                           _("ICC profile validation failed: "
+                             "Parasite's name is not 'icc-profile'"));
+      return FALSE;
+    }
+
+  if (gimp_parasite_flags (icc_parasite) != (GIMP_PARASITE_PERSISTENT |
+                                             GIMP_PARASITE_UNDOABLE))
+    {
+      g_set_error_literal (error, GIMP_ERROR, GIMP_FAILED,
+                           _("ICC profile validation failed: "
+                             "Parasite's flags are not (PERSISTENT | UNDOABLE)"));
+      return FALSE;
+    }
+
+  return gimp_image_validate_icc_profile (image,
+                                          gimp_parasite_data (icc_parasite),
+                                          gimp_parasite_data_size (icc_parasite),
+                                          is_builtin,
+                                          error);
+}
+
+const GimpParasite *
+gimp_image_get_icc_parasite (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  return gimp_image_parasite_find (image, GIMP_ICC_PROFILE_PARASITE_NAME);
+}
+
+void
+gimp_image_set_icc_parasite (GimpImage          *image,
+                             const GimpParasite *icc_parasite)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  if (icc_parasite)
+    {
+      g_return_if_fail (gimp_image_validate_icc_parasite (image, icc_parasite,
+                                                          NULL, NULL) == TRUE);
+
+      gimp_image_parasite_attach (image, icc_parasite, TRUE);
+    }
+  else
+    {
+      gimp_image_parasite_detach (image, GIMP_ICC_PROFILE_PARASITE_NAME, TRUE);
+    }
+}
+
+gboolean
+gimp_image_validate_icc_profile (GimpImage     *image,
+                                 const guint8  *data,
+                                 gsize          length,
+                                 gboolean      *is_builtin,
+                                 GError       **error)
+{
+  GimpColorProfile *profile;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+  g_return_val_if_fail (data != NULL || length == 0, FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  profile = gimp_color_profile_new_from_icc_profile (data, length, error);
+
+  if (! profile)
+    {
+      g_prefix_error (error, _("ICC profile validation failed: "));
+      return FALSE;
+    }
+
+  if (! gimp_image_validate_color_profile (image, profile, is_builtin, error))
+    {
+      g_object_unref (profile);
+      return FALSE;
+    }
+
+  g_object_unref (profile);
+
+  return TRUE;
+}
+
+const guint8 *
+gimp_image_get_icc_profile (GimpImage *image,
+                            gsize     *length)
+{
+  const GimpParasite *parasite;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+
+  parasite = gimp_image_parasite_find (image, GIMP_ICC_PROFILE_PARASITE_NAME);
+
+  if (parasite)
+    {
+      if (length)
+        *length = gimp_parasite_data_size (parasite);
+
+      return gimp_parasite_data (parasite);
+    }
+
+  if (length)
+    *length = 0;
+
+  return NULL;
+}
+
+gboolean
+gimp_image_set_icc_profile (GimpImage     *image,
+                            const guint8  *data,
+                            gsize          length,
+                            GError       **error)
+{
+  GimpParasite *parasite = NULL;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+  g_return_val_if_fail (data == NULL || length != 0, FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  if (data)
+    {
+      gboolean is_builtin;
+
+      parasite = gimp_parasite_new (GIMP_ICC_PROFILE_PARASITE_NAME,
+                                    GIMP_PARASITE_PERSISTENT |
+                                    GIMP_PARASITE_UNDOABLE,
+                                    length, data);
+
+      if (! gimp_image_validate_icc_parasite (image, parasite, &is_builtin,
+                                              error))
+        {
+          gimp_parasite_free (parasite);
+          return FALSE;
+        }
+
+      /*  don't tag the image with the built-in profile  */
+      if (is_builtin)
+        {
+          gimp_parasite_free (parasite);
+          parasite = NULL;
+        }
+    }
+
+  gimp_image_set_icc_parasite (image, parasite);
+
+  if (parasite)
+    gimp_parasite_free (parasite);
+
+  return TRUE;
+}
+
+gboolean
+gimp_image_validate_color_profile (GimpImage        *image,
+                                   GimpColorProfile *profile,
+                                   gboolean         *is_builtin,
+                                   GError          **error)
+{
+  const Babl *format;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+  g_return_val_if_fail (GIMP_IS_COLOR_PROFILE (profile), FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  format = gimp_image_get_layer_format (image, TRUE);
+
+  return gimp_image_validate_color_profile_by_format (format,
+                                                      profile, is_builtin,
+                                                      error);
+}
+
+GimpColorProfile *
+gimp_image_get_color_profile (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->color_profile;
+}
+
+gboolean
+gimp_image_set_color_profile (GimpImage         *image,
+                              GimpColorProfile  *profile,
+                              GError           **error)
+{
+  const guint8 *data   = NULL;
+  gsize         length = 0;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+  g_return_val_if_fail (profile == NULL || GIMP_IS_COLOR_PROFILE (profile),
+                        FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  if (profile)
+    data = gimp_color_profile_get_icc_profile (profile, &length);
+
+  return gimp_image_set_icc_profile (image, data, length, error);
+}
+
+gboolean
+gimp_image_validate_color_profile_by_format (const Babl         *format,
+                                             GimpColorProfile   *profile,
+                                             gboolean           *is_builtin,
+                                             GError            **error)
+{
+  g_return_val_if_fail (format != NULL, FALSE);
+  g_return_val_if_fail (GIMP_IS_COLOR_PROFILE (profile), FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  if (gimp_babl_format_get_base_type (format) == GIMP_GRAY)
+    {
+      if (! gimp_color_profile_is_gray (profile))
+        {
+          g_set_error_literal (error, GIMP_ERROR, GIMP_FAILED,
+                               _("ICC profile validation failed: "
+                                 "Color profile is not for grayscale color space"));
+          return FALSE;
+        }
+    }
+  else
+    {
+      if (! gimp_color_profile_is_rgb (profile))
+        {
+          g_set_error_literal (error, GIMP_ERROR, GIMP_FAILED,
+                               _("ICC profile validation failed: "
+                                 "Color profile is not for RGB color space"));
+          return FALSE;
+        }
+    }
+
+  if (is_builtin)
+    {
+      GimpColorProfile *builtin;
+
+      builtin = gimp_babl_format_get_color_profile (format);
+
+      *is_builtin = gimp_color_profile_is_equal (profile, builtin);
+    }
+
+  return TRUE;
+}
+
+GimpColorProfile *
+gimp_image_get_builtin_color_profile (GimpImage *image)
+{
+  const Babl *format;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  format = gimp_image_get_layer_format (image, FALSE);
+
+  return gimp_babl_format_get_color_profile (format);
+}
+
+gboolean
+gimp_image_convert_color_profile (GimpImage                *image,
+                                  GimpColorProfile         *dest_profile,
+                                  GimpColorRenderingIntent  intent,
+                                  gboolean                  bpc,
+                                  GimpProgress             *progress,
+                                  GError                  **error)
+{
+  GimpColorProfile *src_profile;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+  g_return_val_if_fail (GIMP_IS_COLOR_PROFILE (dest_profile), FALSE);
+  g_return_val_if_fail (progress == NULL || GIMP_IS_PROGRESS (progress), FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  if (! gimp_image_validate_color_profile (image, dest_profile, NULL, error))
+    return FALSE;
+
+  src_profile = gimp_color_managed_get_color_profile (GIMP_COLOR_MANAGED (image));
+
+  if (! src_profile || gimp_color_profile_is_equal (src_profile, dest_profile))
+    return TRUE;
+
+  if (progress)
+    gimp_progress_start (progress, FALSE,
+                         _("Converting from '%s' to '%s'"),
+                         gimp_color_profile_get_label (src_profile),
+                         gimp_color_profile_get_label (dest_profile));
+
+  gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_IMAGE_CONVERT,
+                               _("Color profile conversion"));
+
+  switch (gimp_image_get_base_type (image))
+    {
+    case GIMP_RGB:
+    case GIMP_GRAY:
+      gimp_image_convert_profile_layers (image,
+                                         src_profile, dest_profile,
+                                         intent, bpc,
+                                         progress);
+      break;
+
+    case GIMP_INDEXED:
+      gimp_image_convert_profile_colormap (image,
+                                           src_profile, dest_profile,
+                                           intent, bpc,
+                                           progress);
+      break;
+    }
+
+  gimp_image_set_is_color_managed (image, TRUE, TRUE);
+  gimp_image_set_color_profile (image, dest_profile, NULL);
+  /*  omg...  */
+  gimp_image_parasite_detach (image, "icc-profile-name", TRUE);
+
+  gimp_image_undo_group_end (image);
+
+  if (progress)
+    gimp_progress_end (progress);
+
+  return TRUE;
+}
+
+void
+gimp_image_import_color_profile (GimpImage    *image,
+                                 GimpContext  *context,
+                                 GimpProgress *progress,
+                                 gboolean      interactive)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+  g_return_if_fail (progress == NULL || GIMP_IS_PROGRESS (progress));
+
+  if (gimp_image_get_is_color_managed (image) &&
+      gimp_image_get_color_profile (image))
+    {
+      GimpColorProfilePolicy     policy;
+      GimpColorProfile          *dest_profile = NULL;
+      GimpColorRenderingIntent   intent;
+      gboolean                   bpc;
+
+      policy = GIMP_DIALOG_CONFIG (image->gimp->config)->color_profile_policy;
+      intent = GIMP_COLOR_RENDERING_INTENT_RELATIVE_COLORIMETRIC;
+      bpc    = TRUE;
+
+      if (policy == GIMP_COLOR_PROFILE_POLICY_ASK)
+        {
+          if (interactive)
+            {
+              gboolean dont_ask = FALSE;
+
+              policy = gimp_query_profile_policy (image->gimp, image, context,
+                                                  &dest_profile,
+                                                  &intent, &bpc,
+                                                  &dont_ask);
+
+              if (dont_ask)
+                {
+                  g_object_set (G_OBJECT (image->gimp->config),
+                                "color-profile-policy", policy,
+                                NULL);
+                }
+            }
+          else
+            {
+              policy = GIMP_COLOR_PROFILE_POLICY_KEEP;
+            }
+        }
+
+      if (policy == GIMP_COLOR_PROFILE_POLICY_CONVERT)
+        {
+          if (! dest_profile)
+            {
+              dest_profile = gimp_image_get_builtin_color_profile (image);
+              g_object_ref (dest_profile);
+            }
+
+          gimp_image_convert_color_profile (image, dest_profile,
+                                            intent, bpc,
+                                            progress, NULL);
+
+          g_object_unref (dest_profile);
+        }
+    }
+}
+
+GimpColorTransform *
+gimp_image_get_color_transform_to_srgb_u8 (GimpImage *image)
+{
+  GimpImagePrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  gimp_image_create_color_transforms (image);
+
+  if (private->is_color_managed)
+    return private->transform_to_srgb_u8;
+
+  return NULL;
+}
+
+GimpColorTransform *
+gimp_image_get_color_transform_from_srgb_u8 (GimpImage *image)
+{
+  GimpImagePrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  gimp_image_create_color_transforms (image);
+
+  if (private->is_color_managed)
+    return private->transform_from_srgb_u8;
+
+  return NULL;
+}
+
+GimpColorTransform *
+gimp_image_get_color_transform_to_srgb_double (GimpImage *image)
+{
+  GimpImagePrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  gimp_image_create_color_transforms (image);
+
+  if (private->is_color_managed)
+    return private->transform_to_srgb_double;
+
+  return NULL;
+}
+
+GimpColorTransform *
+gimp_image_get_color_transform_from_srgb_double (GimpImage *image)
+{
+  GimpImagePrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  gimp_image_create_color_transforms (image);
+
+  if (private->is_color_managed)
+    return private->transform_from_srgb_double;
+
+  return NULL;
+}
+
+void
+gimp_image_color_profile_pixel_to_srgb (GimpImage  *image,
+                                        const Babl *pixel_format,
+                                        gpointer    pixel,
+                                        GimpRGB    *color)
+{
+  GimpColorTransform *transform;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  transform = gimp_image_get_color_transform_to_srgb_double (image);
+
+  if (transform)
+    {
+      gimp_color_transform_process_pixels (transform,
+                                           pixel_format,
+                                           pixel,
+                                           babl_format ("R'G'B'A double"),
+                                           color,
+                                           1);
+    }
+  else
+    {
+      gimp_rgba_set_pixel (color, pixel_format, pixel);
+    }
+}
+
+void
+gimp_image_color_profile_srgb_to_pixel (GimpImage     *image,
+                                        const GimpRGB *color,
+                                        const Babl    *pixel_format,
+                                        gpointer       pixel)
+{
+  GimpColorTransform *transform;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  transform = gimp_image_get_color_transform_from_srgb_double (image);
+
+  if (transform)
+    {
+      gimp_color_transform_process_pixels (transform,
+                                           babl_format ("R'G'B'A double"),
+                                           color,
+                                           pixel_format,
+                                           pixel,
+                                           1);
+    }
+  else
+    {
+      gimp_rgba_get_pixel (color, pixel_format, pixel);
+    }
+}
+
+
+/*  internal API  */
+
+void
+_gimp_image_free_color_profile (GimpImage *image)
+{
+  GimpImagePrivate *private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  g_clear_object (&private->color_profile);
+
+  _gimp_image_free_color_transforms (image);
+}
+
+void
+_gimp_image_free_color_transforms (GimpImage *image)
+{
+  GimpImagePrivate *private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  g_clear_object (&private->transform_to_srgb_u8);
+  g_clear_object (&private->transform_from_srgb_u8);
+  g_clear_object (&private->transform_to_srgb_double);
+  g_clear_object (&private->transform_from_srgb_double);
+
+  private->color_transforms_created = FALSE;
+}
+
+void
+_gimp_image_update_color_profile (GimpImage          *image,
+                                  const GimpParasite *icc_parasite)
+{
+  GimpImagePrivate *private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  _gimp_image_free_color_profile (image);
+
+  if (icc_parasite)
+    {
+      private->color_profile =
+        gimp_color_profile_new_from_icc_profile (gimp_parasite_data (icc_parasite),
+                                                 gimp_parasite_data_size (icc_parasite),
+                                                 NULL);
+    }
+
+  gimp_color_managed_profile_changed (GIMP_COLOR_MANAGED (image));
+}
+
+
+/*  private functions  */
+
+static void
+gimp_image_convert_profile_layers (GimpImage                *image,
+                                   GimpColorProfile         *src_profile,
+                                   GimpColorProfile         *dest_profile,
+                                   GimpColorRenderingIntent  intent,
+                                   gboolean                  bpc,
+                                   GimpProgress             *progress)
+{
+  GimpObjectQueue *queue;
+  GList           *layers;
+  GList           *list;
+  GimpDrawable    *drawable;
+
+  queue    = gimp_object_queue_new (progress);
+  progress = GIMP_PROGRESS (queue);
+
+  layers = gimp_image_get_layer_list (image);
+
+  for (list = layers; list; list = g_list_next (list))
+    {
+      if (! gimp_viewable_get_children (list->data))
+        gimp_object_queue_push (queue, list->data);
+    }
+
+  g_list_free (layers);
+
+  while ((drawable = gimp_object_queue_pop (queue)))
+    {
+      GimpItem   *item = GIMP_ITEM (drawable);
+      GeglBuffer *buffer;
+      gboolean    alpha;
+
+      alpha = gimp_drawable_has_alpha (drawable);
+
+      buffer = gegl_buffer_new (GEGL_RECTANGLE (0, 0,
+                                                gimp_item_get_width  (item),
+                                                gimp_item_get_height (item)),
+                                gimp_image_get_layer_format (image, alpha));
+
+      gimp_drawable_push_undo (drawable, NULL, NULL,
+                               0, 0,
+                               gimp_item_get_width  (GIMP_ITEM (drawable)),
+                               gimp_item_get_height (GIMP_ITEM (drawable)));
+
+      gimp_gegl_convert_color_profile (gimp_drawable_get_buffer (drawable),
+                                       NULL,
+                                       src_profile,
+                                       buffer,
+                                       NULL,
+                                       dest_profile,
+                                       intent, bpc,
+                                       progress);
+
+      gimp_drawable_set_buffer (drawable, TRUE, NULL, buffer);
+      g_object_unref (buffer);
+    }
+
+  g_object_unref (queue);
+}
+
+static void
+gimp_image_convert_profile_colormap (GimpImage                *image,
+                                     GimpColorProfile         *src_profile,
+                                     GimpColorProfile         *dest_profile,
+                                     GimpColorRenderingIntent  intent,
+                                     gboolean                  bpc,
+                                     GimpProgress             *progress)
+{
+  GimpColorTransform      *transform;
+  GimpColorTransformFlags  flags = 0;
+  guchar                  *cmap;
+  gint                     n_colors;
+
+  n_colors = gimp_image_get_colormap_size (image);
+  cmap     = g_memdup (gimp_image_get_colormap (image), n_colors * 3);
+
+  if (bpc)
+    flags |= GIMP_COLOR_TRANSFORM_FLAGS_BLACK_POINT_COMPENSATION;
+
+  transform = gimp_color_transform_new (src_profile,
+                                        babl_format ("R'G'B' u8"),
+                                        dest_profile,
+                                        babl_format ("R'G'B' u8"),
+                                        intent, flags);
+
+  if (transform)
+    {
+      gimp_color_transform_process_pixels (transform,
+                                           babl_format ("R'G'B' u8"), cmap,
+                                           babl_format ("R'G'B' u8"), cmap,
+                                           n_colors);
+      g_object_unref (transform);
+
+      gimp_image_set_colormap (image, cmap, n_colors, TRUE);
+    }
+  else
+    {
+      g_warning ("cmsCreateTransform() failed!");
+    }
+
+  g_free (cmap);
+}
+
+static void
+gimp_image_create_color_transforms (GimpImage *image)
+{
+  GimpImagePrivate *private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  if (private->color_profile &&
+      ! private->color_transforms_created)
+    {
+      GimpColorProfile        *srgb_profile;
+      GimpColorTransformFlags  flags = 0;
+
+      srgb_profile = gimp_color_profile_new_rgb_srgb ();
+
+      flags |= GIMP_COLOR_TRANSFORM_FLAGS_NOOPTIMIZE;
+      flags |= GIMP_COLOR_TRANSFORM_FLAGS_BLACK_POINT_COMPENSATION;
+
+      private->transform_to_srgb_u8 =
+        gimp_color_transform_new (private->color_profile,
+                                  gimp_image_get_layer_format (image, TRUE),
+                                  srgb_profile,
+                                  babl_format ("R'G'B'A u8"),
+                                  GIMP_COLOR_RENDERING_INTENT_PERCEPTUAL,
+                                  flags);
+
+      private->transform_from_srgb_u8 =
+        gimp_color_transform_new (srgb_profile,
+                                  babl_format ("R'G'B'A u8"),
+                                  private->color_profile,
+                                  gimp_image_get_layer_format (image, TRUE),
+                                  GIMP_COLOR_RENDERING_INTENT_PERCEPTUAL,
+                                  flags);
+
+      private->transform_to_srgb_double =
+        gimp_color_transform_new (private->color_profile,
+                                  gimp_image_get_layer_format (image, TRUE),
+                                  srgb_profile,
+                                  babl_format ("R'G'B'A double"),
+                                  GIMP_COLOR_RENDERING_INTENT_PERCEPTUAL,
+                                  flags);
+
+      private->transform_from_srgb_double =
+        gimp_color_transform_new (srgb_profile,
+                                  babl_format ("R'G'B'A double"),
+                                  private->color_profile,
+                                  gimp_image_get_layer_format (image, TRUE),
+                                  GIMP_COLOR_RENDERING_INTENT_PERCEPTUAL,
+                                  flags);
+
+      g_object_unref (srgb_profile);
+
+      private->color_transforms_created = TRUE;
+    }
+}
diff --git a/app/core/gimpimage-color-profile.h b/app/core/gimpimage-color-profile.h
new file mode 100644
index 0000000..ae89038
--- /dev/null
+++ b/app/core/gimpimage-color-profile.h
@@ -0,0 +1,113 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpimage-color-profile.h
+ * Copyright (C) 2015 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_IMAGE_COLOR_PROFILE_H__
+#define __GIMP_IMAGE_COLOR_PROFILE_H__
+
+
+#define GIMP_ICC_PROFILE_PARASITE_NAME "icc-profile"
+
+
+gboolean             gimp_image_get_is_color_managed   (GimpImage           *image);
+void                 gimp_image_set_is_color_managed   (GimpImage           *image,
+                                                        gboolean             is_color_managed,
+                                                        gboolean             push_undo);
+
+gboolean             gimp_image_validate_icc_parasite  (GimpImage           *image,
+                                                        const GimpParasite  *icc_parasite,
+                                                        gboolean            *is_builtin,
+                                                        GError             **error);
+const GimpParasite * gimp_image_get_icc_parasite       (GimpImage           *image);
+void                 gimp_image_set_icc_parasite       (GimpImage           *image,
+                                                        const GimpParasite  *icc_parasite);
+
+gboolean             gimp_image_validate_icc_profile   (GimpImage           *image,
+                                                        const guint8        *data,
+                                                        gsize                length,
+                                                        gboolean            *is_builtin,
+                                                        GError             **error);
+const guint8       * gimp_image_get_icc_profile        (GimpImage           *image,
+                                                        gsize               *length);
+gboolean             gimp_image_set_icc_profile        (GimpImage           *image,
+                                                        const guint8        *data,
+                                                        gsize                length,
+                                                        GError             **error);
+
+gboolean             gimp_image_validate_color_profile (GimpImage           *image,
+                                                        GimpColorProfile    *profile,
+                                                        gboolean            *is_builtin,
+                                                        GError             **error);
+GimpColorProfile   * gimp_image_get_color_profile      (GimpImage           *image);
+gboolean             gimp_image_set_color_profile      (GimpImage           *image,
+                                                        GimpColorProfile    *profile,
+                                                        GError             **error);
+
+gboolean             gimp_image_validate_color_profile_by_format
+                                                       (const Babl          *format,
+                                                        GimpColorProfile    *profile,
+                                                        gboolean            *is_builtin,
+                                                        GError             **error);
+
+GimpColorProfile   * gimp_image_get_builtin_color_profile
+                                                       (GimpImage           *image);
+
+gboolean             gimp_image_convert_color_profile  (GimpImage           *image,
+                                                        GimpColorProfile    *dest_profile,
+                                                        GimpColorRenderingIntent  intent,
+                                                        gboolean             bpc,
+                                                        GimpProgress        *progress,
+                                                        GError             **error);
+
+void                 gimp_image_import_color_profile   (GimpImage           *image,
+                                                        GimpContext         *context,
+                                                        GimpProgress        *progress,
+                                                        gboolean             interactive);
+
+GimpColorTransform * gimp_image_get_color_transform_to_srgb_u8
+                                                       (GimpImage           *image);
+GimpColorTransform * gimp_image_get_color_transform_from_srgb_u8
+                                                       (GimpImage           *image);
+
+GimpColorTransform * gimp_image_get_color_transform_to_srgb_double
+                                                       (GimpImage           *image);
+GimpColorTransform * gimp_image_get_color_transform_from_srgb_double
+                                                       (GimpImage           *image);
+
+void                 gimp_image_color_profile_pixel_to_srgb
+                                                       (GimpImage           *image,
+                                                        const Babl          *pixel_format,
+                                                        gpointer             pixel,
+                                                        GimpRGB             *color);
+void                 gimp_image_color_profile_srgb_to_pixel
+                                                       (GimpImage           *image,
+                                                        const GimpRGB       *color,
+                                                        const Babl          *pixel_format,
+                                                        gpointer             pixel);
+
+
+/*  internal API, to be called only from gimpimage.c  */
+
+void                 _gimp_image_free_color_profile    (GimpImage           *image);
+void                 _gimp_image_free_color_transforms (GimpImage           *image);
+void                 _gimp_image_update_color_profile  (GimpImage           *image,
+                                                        const GimpParasite  *icc_parasite);
+
+
+#endif /* __GIMP_IMAGE_COLOR_PROFILE_H__ */
diff --git a/app/core/gimpimage-colormap.c b/app/core/gimpimage-colormap.c
new file mode 100644
index 0000000..8bf40a9
--- /dev/null
+++ b/app/core/gimpimage-colormap.c
@@ -0,0 +1,362 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <cairo.h>
+#include <gegl.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "libgimpcolor/gimpcolor.h"
+
+#include "core-types.h"
+
+#include "gimp.h"
+#include "gimpcontainer.h"
+#include "gimpdatafactory.h"
+#include "gimpimage.h"
+#include "gimpimage-colormap.h"
+#include "gimpimage-private.h"
+#include "gimpimage-undo-push.h"
+#include "gimppalette.h"
+
+#include "gimp-intl.h"
+
+
+/*  local function prototype  */
+
+static void   gimp_image_colormap_set_palette_entry (GimpImage     *image,
+                                                     const GimpRGB *color,
+                                                     gint           index);
+
+
+/*  public functions  */
+
+void
+gimp_image_colormap_init (GimpImage *image)
+{
+  GimpImagePrivate *private;
+  GimpContainer    *palettes;
+  gchar            *palette_name;
+  gchar            *palette_id;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  g_return_if_fail (private->colormap == NULL);
+  g_return_if_fail (private->palette == NULL);
+
+  palette_name = g_strdup_printf (_("Colormap of Image #%d (%s)"),
+                                  gimp_image_get_ID (image),
+                                  gimp_image_get_display_name (image));
+  palette_id = g_strdup_printf ("gimp-indexed-image-palette-%d",
+                                gimp_image_get_ID (image));
+
+  private->n_colors = 0;
+  private->colormap = g_new0 (guchar, GIMP_IMAGE_COLORMAP_SIZE);
+  private->palette  = GIMP_PALETTE (gimp_palette_new (NULL, palette_name));
+
+  if (! private->babl_palette_rgb)
+    {
+      gchar *format_name = g_strdup_printf ("-gimp-indexed-format-%d",
+                                            gimp_image_get_ID (image));
+
+      babl_new_palette (format_name,
+                        &private->babl_palette_rgb,
+                        &private->babl_palette_rgba);
+
+      g_free (format_name);
+    }
+
+  gimp_palette_set_columns (private->palette, 16);
+
+  gimp_data_make_internal (GIMP_DATA (private->palette), palette_id);
+
+  palettes = gimp_data_factory_get_container (image->gimp->palette_factory);
+
+  gimp_container_add (palettes, GIMP_OBJECT (private->palette));
+
+  g_free (palette_name);
+  g_free (palette_id);
+}
+
+void
+gimp_image_colormap_dispose (GimpImage *image)
+{
+  GimpImagePrivate *private;
+  GimpContainer    *palettes;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  g_return_if_fail (private->colormap != NULL);
+  g_return_if_fail (GIMP_IS_PALETTE (private->palette));
+
+  palettes = gimp_data_factory_get_container (image->gimp->palette_factory);
+
+  gimp_container_remove (palettes, GIMP_OBJECT (private->palette));
+}
+
+void
+gimp_image_colormap_free (GimpImage *image)
+{
+  GimpImagePrivate *private;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  g_return_if_fail (private->colormap != NULL);
+  g_return_if_fail (GIMP_IS_PALETTE (private->palette));
+
+  g_clear_pointer (&private->colormap, g_free);
+  g_clear_object (&private->palette);
+
+  /* don't touch the image's babl_palettes because we might still have
+   * buffers with that palette on the undo stack, and on undoing the
+   * image back to indexed, we must have exactly these palettes around
+   */
+}
+
+const Babl *
+gimp_image_colormap_get_rgb_format (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->babl_palette_rgb;
+}
+
+const Babl *
+gimp_image_colormap_get_rgba_format (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->babl_palette_rgba;
+}
+
+GimpPalette *
+gimp_image_get_colormap_palette (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->palette;
+}
+
+const guchar *
+gimp_image_get_colormap (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->colormap;
+}
+
+gint
+gimp_image_get_colormap_size (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), 0);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->n_colors;
+}
+
+void
+gimp_image_set_colormap (GimpImage    *image,
+                         const guchar *colormap,
+                         gint          n_colors,
+                         gboolean      push_undo)
+{
+  GimpImagePrivate *private;
+  GimpPaletteEntry *entry;
+  gint              i;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (colormap != NULL || n_colors == 0);
+  g_return_if_fail (n_colors >= 0 && n_colors <= 256);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  if (push_undo)
+    gimp_image_undo_push_image_colormap (image, C_("undo-type", "Set Colormap"));
+
+  if (private->colormap)
+    memset (private->colormap, 0, GIMP_IMAGE_COLORMAP_SIZE);
+  else
+    gimp_image_colormap_init (image);
+
+  if (colormap)
+    memcpy (private->colormap, colormap, n_colors * 3);
+
+  /* make sure the image's colormap always has at least one color.  when
+   * n_colors == 0, use black.
+   */
+  private->n_colors = MAX (n_colors, 1);
+
+  gimp_data_freeze (GIMP_DATA (private->palette));
+
+  while ((entry = gimp_palette_get_entry (private->palette, 0)))
+    gimp_palette_delete_entry (private->palette, entry);
+
+  for (i = 0; i < private->n_colors; i++)
+    gimp_image_colormap_set_palette_entry (image, NULL, i);
+
+  gimp_data_thaw (GIMP_DATA (private->palette));
+
+  gimp_image_colormap_changed (image, -1);
+}
+
+void
+gimp_image_unset_colormap (GimpImage *image,
+                           gboolean   push_undo)
+{
+  GimpImagePrivate *private;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  if (push_undo)
+    gimp_image_undo_push_image_colormap (image,
+                                         C_("undo-type", "Unset Colormap"));
+
+  if (private->colormap)
+    {
+      gimp_image_colormap_dispose (image);
+      gimp_image_colormap_free (image);
+    }
+
+  private->n_colors = 0;
+
+  gimp_image_colormap_changed (image, -1);
+}
+
+void
+gimp_image_get_colormap_entry (GimpImage *image,
+                               gint       color_index,
+                               GimpRGB   *color)
+{
+  GimpImagePrivate *private;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  g_return_if_fail (private->colormap != NULL);
+  g_return_if_fail (color_index >= 0 && color_index < private->n_colors);
+  g_return_if_fail (color != NULL);
+
+  gimp_rgba_set_uchar (color,
+                       private->colormap[color_index * 3],
+                       private->colormap[color_index * 3 + 1],
+                       private->colormap[color_index * 3 + 2],
+                       255);
+}
+
+void
+gimp_image_set_colormap_entry (GimpImage     *image,
+                               gint           color_index,
+                               const GimpRGB *color,
+                               gboolean       push_undo)
+{
+  GimpImagePrivate *private;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  g_return_if_fail (private->colormap != NULL);
+  g_return_if_fail (color_index >= 0 && color_index < private->n_colors);
+  g_return_if_fail (color != NULL);
+
+  if (push_undo)
+    gimp_image_undo_push_image_colormap (image,
+                                         C_("undo-type", "Change Colormap entry"));
+
+  gimp_rgb_get_uchar (color,
+                      &private->colormap[color_index * 3],
+                      &private->colormap[color_index * 3 + 1],
+                      &private->colormap[color_index * 3 + 2]);
+
+  if (private->palette)
+    gimp_image_colormap_set_palette_entry (image, color, color_index);
+
+  gimp_image_colormap_changed (image, color_index);
+}
+
+void
+gimp_image_add_colormap_entry (GimpImage     *image,
+                               const GimpRGB *color)
+{
+  GimpImagePrivate *private;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  g_return_if_fail (private->colormap != NULL);
+  g_return_if_fail (private->n_colors < 256);
+  g_return_if_fail (color != NULL);
+
+  gimp_image_undo_push_image_colormap (image,
+                                       C_("undo-type", "Add Color to Colormap"));
+
+  gimp_rgb_get_uchar (color,
+                      &private->colormap[private->n_colors * 3],
+                      &private->colormap[private->n_colors * 3 + 1],
+                      &private->colormap[private->n_colors * 3 + 2]);
+
+  private->n_colors++;
+
+  if (private->palette)
+    gimp_image_colormap_set_palette_entry (image, color, private->n_colors - 1);
+
+  gimp_image_colormap_changed (image, -1);
+}
+
+
+/*  private functions  */
+
+static void
+gimp_image_colormap_set_palette_entry (GimpImage     *image,
+                                       const GimpRGB *c,
+                                       gint           index)
+{
+  GimpImagePrivate *private = GIMP_IMAGE_GET_PRIVATE (image);
+  GimpRGB           color;
+  gchar             name[64];
+
+  /* Avoid converting to char then back to double if we have the
+   * original GimpRGB color.
+   */
+  if (c)
+    color = *c;
+  else
+    gimp_rgba_set_uchar (&color,
+                         private->colormap[3 * index + 0],
+                         private->colormap[3 * index + 1],
+                         private->colormap[3 * index + 2],
+                         255);
+
+  g_snprintf (name, sizeof (name), "#%d", index);
+
+  if (gimp_palette_get_n_colors (private->palette) < private->n_colors)
+    gimp_palette_add_entry (private->palette, index, name, &color);
+  else
+    gimp_palette_set_entry (private->palette, index, name, &color);
+}
diff --git a/app/core/gimpimage-colormap.h b/app/core/gimpimage-colormap.h
new file mode 100644
index 0000000..703f5a2
--- /dev/null
+++ b/app/core/gimpimage-colormap.h
@@ -0,0 +1,55 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattisbvf
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_IMAGE_COLORMAP_H__
+#define __GIMP_IMAGE_COLORMAP_H__
+
+
+#define GIMP_IMAGE_COLORMAP_SIZE 768
+
+
+void           gimp_image_colormap_init            (GimpImage     *image);
+void           gimp_image_colormap_dispose         (GimpImage     *image);
+void           gimp_image_colormap_free            (GimpImage     *image);
+
+const Babl   * gimp_image_colormap_get_rgb_format  (GimpImage     *image);
+const Babl   * gimp_image_colormap_get_rgba_format (GimpImage     *image);
+
+GimpPalette  * gimp_image_get_colormap_palette     (GimpImage     *image);
+
+const guchar * gimp_image_get_colormap             (GimpImage     *image);
+gint           gimp_image_get_colormap_size        (GimpImage     *image);
+void           gimp_image_set_colormap             (GimpImage     *image,
+                                                    const guchar  *colormap,
+                                                    gint           n_colors,
+                                                    gboolean       push_undo);
+void           gimp_image_unset_colormap           (GimpImage     *image,
+                                                    gboolean       push_undo);
+
+void           gimp_image_get_colormap_entry       (GimpImage     *image,
+                                                    gint           color_index,
+                                                    GimpRGB       *color);
+void           gimp_image_set_colormap_entry       (GimpImage     *image,
+                                                    gint           color_index,
+                                                    const GimpRGB *color,
+                                                    gboolean       push_undo);
+
+void           gimp_image_add_colormap_entry       (GimpImage     *image,
+                                                    const GimpRGB *color);
+
+
+#endif /* __GIMP_IMAGE_COLORMAP_H__ */
diff --git a/app/core/gimpimage-convert-data.h b/app/core/gimpimage-convert-data.h
new file mode 100644
index 0000000..dd0dd11
--- /dev/null
+++ b/app/core/gimpimage-convert-data.h
@@ -0,0 +1,143 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/* Misc data definitions used by the convert.c code module.  Moved
+   out here simply to unclutter convert.c, mostly. */
+
+#ifndef __GIMP_IMAGE_CONVERT_DATA_H__
+#define __GIMP_IMAGE_CONVERT_DATA_H__
+
+#include <glib.h>
+
+/* 'web safe' palette. */
+static const guchar webpal[] =
+{
+  255,255,255,255,255,204,255,255,153,255,255,102,255,255,51,255,255,0,255,
+  204,255,255,204,204,255,204,153,255,204,102,255,204,51,255,204,0,255,153,
+  255,255,153,204,255,153,153,255,153,102,255,153,51,255,153,0,255,102,255,
+  255,102,204,255,102,153,255,102,102,255,102,51,255,102,0,255,51,255,255,
+  51,204,255,51,153,255,51,102,255,51,51,255,51,0,255,0,255,255,0,
+  204,255,0,153,255,0,102,255,0,51,255,0,0,204,255,255,204,255,204,
+  204,255,153,204,255,102,204,255,51,204,255,0,204,204,255,204,204,204,204,
+  204,153,204,204,102,204,204,51,204,204,0,204,153,255,204,153,204,204,153,
+  153,204,153,102,204,153,51,204,153,0,204,102,255,204,102,204,204,102,153,
+  204,102,102,204,102,51,204,102,0,204,51,255,204,51,204,204,51,153,204,
+  51,102,204,51,51,204,51,0,204,0,255,204,0,204,204,0,153,204,0,
+  102,204,0,51,204,0,0,153,255,255,153,255,204,153,255,153,153,255,102,
+  153,255,51,153,255,0,153,204,255,153,204,204,153,204,153,153,204,102,153,
+  204,51,153,204,0,153,153,255,153,153,204,153,153,153,153,153,102,153,153,
+  51,153,153,0,153,102,255,153,102,204,153,102,153,153,102,102,153,102,51,
+  153,102,0,153,51,255,153,51,204,153,51,153,153,51,102,153,51,51,153,
+  51,0,153,0,255,153,0,204,153,0,153,153,0,102,153,0,51,153,0,
+  0,102,255,255,102,255,204,102,255,153,102,255,102,102,255,51,102,255,0,
+  102,204,255,102,204,204,102,204,153,102,204,102,102,204,51,102,204,0,102,
+  153,255,102,153,204,102,153,153,102,153,102,102,153,51,102,153,0,102,102,
+  255,102,102,204,102,102,153,102,102,102,102,102,51,102,102,0,102,51,255,
+  102,51,204,102,51,153,102,51,102,102,51,51,102,51,0,102,0,255,102,
+  0,204,102,0,153,102,0,102,102,0,51,102,0,0,51,255,255,51,255,
+  204,51,255,153,51,255,102,51,255,51,51,255,0,51,204,255,51,204,204,
+  51,204,153,51,204,102,51,204,51,51,204,0,51,153,255,51,153,204,51,
+  153,153,51,153,102,51,153,51,51,153,0,51,102,255,51,102,204,51,102,
+  153,51,102,102,51,102,51,51,102,0,51,51,255,51,51,204,51,51,153,
+  51,51,102,51,51,51,51,51,0,51,0,255,51,0,204,51,0,153,51,
+  0,102,51,0,51,51,0,0,0,255,255,0,255,204,0,255,153,0,255,
+  102,0,255,51,0,255,0,0,204,255,0,204,204,0,204,153,0,204,102,
+  0,204,51,0,204,0,0,153,255,0,153,204,0,153,153,0,153,102,0,
+  153,51,0,153,0,0,102,255,0,102,204,0,102,153,0,102,102,0,102,
+  51,0,102,0,0,51,255,0,51,204,0,51,153,0,51,102,0,51,51,
+  0,51,0,0,0,255,0,0,204,0,0,153,0,0,102,0,0,51,0,0,0
+};
+
+
+/* the dither matrix, used for alpha dither and 'positional' dither */
+#define DM_WIDTH 32
+#define DM_WIDTHMASK ((DM_WIDTH)-1)
+#define DM_HEIGHT 32
+#define DM_HEIGHTMASK ((DM_HEIGHT)-1)
+/* matrix values should be scaled/biased to 1..255 range */
+/* this array is not const because it may be overwritten. */
+static guchar DM[32][32] = {
+  {  1,191, 48,239, 12,203, 60,251,  3,194, 51,242, 15,206, 63,254,  1,192, 49,240, 13,204, 61,252,  4,195, 52,243, 16,207, 64,255},
+  {128, 64,175,112,140, 76,187,124,131, 67,178,115,143, 79,190,127,128, 65,176,112,140, 77,188,124,131, 68,179,115,143, 80,191,127},
+  { 32,223, 16,207, 44,235, 28,219, 35,226, 19,210, 47,238, 31,222, 33,224, 17,208, 45,236, 29,220, 36,227, 20,211, 48,239, 32,223},
+  {159, 96,144, 80,171,108,155, 92,162, 99,146, 83,174,111,158, 95,160, 97,144, 81,172,109,156, 93,163,100,147, 84,175,111,159, 96},
+  {  8,199, 56,247,  4,195, 52,243, 11,202, 59,250,  7,198, 55,246,  9,200, 57,248,  5,196, 53,244, 12,203, 60,251,  8,199, 56,247},
+  {136, 72,183,120,132, 68,179,116,139, 75,186,123,135, 71,182,119,136, 73,184,120,132, 69,180,116,139, 76,187,123,135, 72,183,119},
+  { 40,231, 24,215, 36,227, 20,211, 43,234, 27,218, 39,230, 23,214, 41,232, 25,216, 37,228, 21,212, 44,235, 28,219, 40,231, 24,215},
+  {167,104,151, 88,163,100,147, 84,170,107,154, 91,166,103,150, 87,168,105,152, 89,164,101,148, 85,171,108,155, 92,167,104,151, 88},
+  {  2,193, 50,241, 14,205, 62,253,  1,192, 49,240, 13,204, 61,252,  3,194, 51,242, 15,206, 63,254,  2,193, 50,241, 14,205, 62,253},
+  {130, 66,177,114,142, 78,189,126,129, 65,176,113,141, 77,188,125,130, 67,178,114,142, 79,190,126,129, 66,177,113,141, 78,189,125},
+  { 34,225, 18,209, 46,237, 30,221, 33,224, 17,208, 45,236, 29,220, 35,226, 19,210, 47,238, 31,222, 34,225, 18,209, 46,237, 30,221},
+  {161, 98,146, 82,173,110,157, 94,160, 97,145, 81,172,109,156, 93,162, 99,146, 83,174,110,158, 95,161, 98,145, 82,173,109,157, 94},
+  { 10,201, 58,249,  6,197, 54,245,  9,200, 57,248,  5,196, 53,244, 11,202, 59,250,  7,198, 55,246, 10,201, 58,249,  6,197, 54,245},
+  {138, 74,185,122,134, 70,181,118,137, 73,184,121,133, 69,180,117,138, 75,186,122,134, 71,182,118,137, 74,185,121,133, 70,181,117},
+  { 42,233, 26,217, 38,229, 22,213, 41,232, 25,216, 37,228, 21,212, 43,234, 27,218, 39,230, 23,214, 42,233, 26,217, 38,229, 22,213},
+  {169,106,153, 90,165,102,149, 86,168,105,152, 89,164,101,148, 85,170,107,154, 91,166,103,150, 87,169,106,153, 90,165,102,149, 86},
+  {  1,192, 49,239, 13,204, 61,251,  4,195, 52,242, 16,207, 64,254,  1,191, 48,239, 13,203, 60,251,  4,194, 51,242, 16,206, 63,254},
+  {128, 65,176,112,140, 76,188,124,131, 68,179,115,143, 79,191,127,128, 64,176,112,140, 76,187,124,131, 67,179,115,143, 79,190,127},
+  { 33,223, 17,208, 45,235, 29,219, 36,226, 20,211, 48,238, 32,222, 33,223, 17,207, 44,235, 29,219, 36,226, 20,210, 47,238, 32,222},
+  {160, 96,144, 80,172,108,156, 92,163, 99,147, 83,175,111,159, 95,160, 96,144, 80,172,108,156, 92,163, 99,147, 83,175,111,159, 95},
+  {  9,200, 57,247,  5,196, 53,243, 12,203, 60,250,  8,199, 56,246,  9,199, 56,247,  5,195, 52,243, 12,202, 59,250,  8,198, 55,246},
+  {136, 73,184,120,132, 69,180,116,139, 75,187,123,135, 72,183,119,136, 72,183,120,132, 68,180,116,139, 75,186,123,135, 71,182,119},
+  { 41,231, 25,216, 37,227, 21,212, 44,234, 28,218, 40,230, 24,215, 40,231, 25,215, 37,227, 21,211, 43,234, 28,218, 39,230, 24,214},
+  {168,104,152, 88,164,100,148, 84,171,107,155, 91,167,103,151, 87,168,104,152, 88,164,100,148, 84,171,107,155, 91,167,103,151, 87},
+  {  3,194, 51,241, 15,206, 63,253,  2,193, 50,240, 14,205, 62,252,  3,193, 50,241, 15,205, 62,253,  2,192, 49,240, 14,204, 61,252},
+  {130, 67,178,114,142, 78,190,126,129, 66,177,113,141, 77,189,125,130, 66,178,114,142, 78,189,126,129, 65,177,113,141, 77,188,125},
+  { 35,225, 19,210, 47,237, 31,221, 34,224, 18,209, 46,236, 30,220, 35,225, 19,209, 46,237, 31,221, 34,224, 18,208, 45,236, 30,220},
+  {162, 98,146, 82,174,110,158, 94,161, 97,145, 81,173,109,157, 93,162, 98,146, 82,174,110,158, 94,161, 97,145, 81,173,109,157, 93},
+  { 11,202, 59,249,  7,198, 55,245, 10,201, 58,248,  6,197, 54,244, 11,201, 58,249,  7,197, 54,245, 10,200, 57,248,  6,196, 53,244},
+  {138, 74,186,122,134, 71,182,118,137, 73,185,121,133, 70,181,117,138, 74,185,122,134, 70,182,118,137, 73,184,121,133, 69,181,117},
+  { 43,233, 27,218, 39,229, 23,214, 42,232, 26,217, 38,228, 22,213, 42,233, 27,217, 38,229, 23,213, 41,232, 26,216, 37,228, 22,212},
+  {170,106,154, 90,166,102,150, 86,169,105,153, 89,165,101,149, 85,170,106,154, 90,166,102,150, 86,169,105,153, 89,165,101,149, 85}
+};
+
+static const guchar DM_ORIGINAL[32][32] = {
+  {  1,191, 48,239, 12,203, 60,251,  3,194, 51,242, 15,206, 63,254,  1,192, 49,240, 13,204, 61,252,  4,195, 52,243, 16,207, 64,255},
+  {128, 64,175,112,140, 76,187,124,131, 67,178,115,143, 79,190,127,128, 65,176,112,140, 77,188,124,131, 68,179,115,143, 80,191,127},
+  { 32,223, 16,207, 44,235, 28,219, 35,226, 19,210, 47,238, 31,222, 33,224, 17,208, 45,236, 29,220, 36,227, 20,211, 48,239, 32,223},
+  {159, 96,144, 80,171,108,155, 92,162, 99,146, 83,174,111,158, 95,160, 97,144, 81,172,109,156, 93,163,100,147, 84,175,111,159, 96},
+  {  8,199, 56,247,  4,195, 52,243, 11,202, 59,250,  7,198, 55,246,  9,200, 57,248,  5,196, 53,244, 12,203, 60,251,  8,199, 56,247},
+  {136, 72,183,120,132, 68,179,116,139, 75,186,123,135, 71,182,119,136, 73,184,120,132, 69,180,116,139, 76,187,123,135, 72,183,119},
+  { 40,231, 24,215, 36,227, 20,211, 43,234, 27,218, 39,230, 23,214, 41,232, 25,216, 37,228, 21,212, 44,235, 28,219, 40,231, 24,215},
+  {167,104,151, 88,163,100,147, 84,170,107,154, 91,166,103,150, 87,168,105,152, 89,164,101,148, 85,171,108,155, 92,167,104,151, 88},
+  {  2,193, 50,241, 14,205, 62,253,  1,192, 49,240, 13,204, 61,252,  3,194, 51,242, 15,206, 63,254,  2,193, 50,241, 14,205, 62,253},
+  {130, 66,177,114,142, 78,189,126,129, 65,176,113,141, 77,188,125,130, 67,178,114,142, 79,190,126,129, 66,177,113,141, 78,189,125},
+  { 34,225, 18,209, 46,237, 30,221, 33,224, 17,208, 45,236, 29,220, 35,226, 19,210, 47,238, 31,222, 34,225, 18,209, 46,237, 30,221},
+  {161, 98,146, 82,173,110,157, 94,160, 97,145, 81,172,109,156, 93,162, 99,146, 83,174,110,158, 95,161, 98,145, 82,173,109,157, 94},
+  { 10,201, 58,249,  6,197, 54,245,  9,200, 57,248,  5,196, 53,244, 11,202, 59,250,  7,198, 55,246, 10,201, 58,249,  6,197, 54,245},
+  {138, 74,185,122,134, 70,181,118,137, 73,184,121,133, 69,180,117,138, 75,186,122,134, 71,182,118,137, 74,185,121,133, 70,181,117},
+  { 42,233, 26,217, 38,229, 22,213, 41,232, 25,216, 37,228, 21,212, 43,234, 27,218, 39,230, 23,214, 42,233, 26,217, 38,229, 22,213},
+  {169,106,153, 90,165,102,149, 86,168,105,152, 89,164,101,148, 85,170,107,154, 91,166,103,150, 87,169,106,153, 90,165,102,149, 86},
+  {  1,192, 49,239, 13,204, 61,251,  4,195, 52,242, 16,207, 64,254,  1,191, 48,239, 13,203, 60,251,  4,194, 51,242, 16,206, 63,254},
+  {128, 65,176,112,140, 76,188,124,131, 68,179,115,143, 79,191,127,128, 64,176,112,140, 76,187,124,131, 67,179,115,143, 79,190,127},
+  { 33,223, 17,208, 45,235, 29,219, 36,226, 20,211, 48,238, 32,222, 33,223, 17,207, 44,235, 29,219, 36,226, 20,210, 47,238, 32,222},
+  {160, 96,144, 80,172,108,156, 92,163, 99,147, 83,175,111,159, 95,160, 96,144, 80,172,108,156, 92,163, 99,147, 83,175,111,159, 95},
+  {  9,200, 57,247,  5,196, 53,243, 12,203, 60,250,  8,199, 56,246,  9,199, 56,247,  5,195, 52,243, 12,202, 59,250,  8,198, 55,246},
+  {136, 73,184,120,132, 69,180,116,139, 75,187,123,135, 72,183,119,136, 72,183,120,132, 68,180,116,139, 75,186,123,135, 71,182,119},
+  { 41,231, 25,216, 37,227, 21,212, 44,234, 28,218, 40,230, 24,215, 40,231, 25,215, 37,227, 21,211, 43,234, 28,218, 39,230, 24,214},
+  {168,104,152, 88,164,100,148, 84,171,107,155, 91,167,103,151, 87,168,104,152, 88,164,100,148, 84,171,107,155, 91,167,103,151, 87},
+  {  3,194, 51,241, 15,206, 63,253,  2,193, 50,240, 14,205, 62,252,  3,193, 50,241, 15,205, 62,253,  2,192, 49,240, 14,204, 61,252},
+  {130, 67,178,114,142, 78,190,126,129, 66,177,113,141, 77,189,125,130, 66,178,114,142, 78,189,126,129, 65,177,113,141, 77,188,125},
+  { 35,225, 19,210, 47,237, 31,221, 34,224, 18,209, 46,236, 30,220, 35,225, 19,209, 46,237, 31,221, 34,224, 18,208, 45,236, 30,220},
+  {162, 98,146, 82,174,110,158, 94,161, 97,145, 81,173,109,157, 93,162, 98,146, 82,174,110,158, 94,161, 97,145, 81,173,109,157, 93},
+  { 11,202, 59,249,  7,198, 55,245, 10,201, 58,248,  6,197, 54,244, 11,201, 58,249,  7,197, 54,245, 10,200, 57,248,  6,196, 53,244},
+  {138, 74,186,122,134, 71,182,118,137, 73,185,121,133, 70,181,117,138, 74,185,122,134, 70,182,118,137, 73,184,121,133, 69,181,117},
+  { 43,233, 27,218, 39,229, 23,214, 42,232, 26,217, 38,228, 22,213, 42,233, 27,217, 38,229, 23,213, 41,232, 26,216, 37,228, 22,212},
+  {170,106,154, 90,166,102,150, 86,169,105,153, 89,165,101,149, 85,170,106,154, 90,166,102,150, 86,169,105,153, 89,165,101,149, 85}
+};
+
+#endif /* __GIMP_IMAGE_CONVERT_DATA_H__ */
diff --git a/app/core/gimpimage-convert-fsdither.h b/app/core/gimpimage-convert-fsdither.h
new file mode 100644
index 0000000..ebd9800
--- /dev/null
+++ b/app/core/gimpimage-convert-fsdither.h
@@ -0,0 +1,559 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_IMAGE_CONVERT_FSDITHER_H__
+#define __GIMP_IMAGE_CONVERT_FSDITHER_H__
+
+/* The following 5 arrays are used in performing floyd-steinberg
+ *  error diffusion dithering. The range array allows the quick
+ *  bounds checking of pixel values. The 4 error arrays contain
+ *  the error computations for the east, south-east, south and
+ *  south-west pixels surrounding the current pixel respectively.
+ */
+
+
+static const guchar range_array[] = {
+    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
+    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
+    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
+    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
+    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
+    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
+    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
+    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
+    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
+    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
+    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
+    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
+    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
+    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
+    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
+    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
+    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
+    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
+    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
+    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
+    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
+    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
+    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
+    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
+    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
+    0,    0,    0,    0,    0,    0,    0,    1,    2,    3,
+    4,    5,    6,    7,    8,    9,   10,   11,   12,   13,
+   14,   15,   16,   17,   18,   19,   20,   21,   22,   23,
+   24,   25,   26,   27,   28,   29,   30,   31,   32,   33,
+   34,   35,   36,   37,   38,   39,   40,   41,   42,   43,
+   44,   45,   46,   47,   48,   49,   50,   51,   52,   53,
+   54,   55,   56,   57,   58,   59,   60,   61,   62,   63,
+   64,   65,   66,   67,   68,   69,   70,   71,   72,   73,
+   74,   75,   76,   77,   78,   79,   80,   81,   82,   83,
+   84,   85,   86,   87,   88,   89,   90,   91,   92,   93,
+   94,   95,   96,   97,   98,   99,  100,  101,  102,  103,
+  104,  105,  106,  107,  108,  109,  110,  111,  112,  113,
+  114,  115,  116,  117,  118,  119,  120,  121,  122,  123,
+  124,  125,  126,  127,  128,  129,  130,  131,  132,  133,
+  134,  135,  136,  137,  138,  139,  140,  141,  142,  143,
+  144,  145,  146,  147,  148,  149,  150,  151,  152,  153,
+  154,  155,  156,  157,  158,  159,  160,  161,  162,  163,
+  164,  165,  166,  167,  168,  169,  170,  171,  172,  173,
+  174,  175,  176,  177,  178,  179,  180,  181,  182,  183,
+  184,  185,  186,  187,  188,  189,  190,  191,  192,  193,
+  194,  195,  196,  197,  198,  199,  200,  201,  202,  203,
+  204,  205,  206,  207,  208,  209,  210,  211,  212,  213,
+  214,  215,  216,  217,  218,  219,  220,  221,  222,  223,
+  224,  225,  226,  227,  228,  229,  230,  231,  232,  233,
+  234,  235,  236,  237,  238,  239,  240,  241,  242,  243,
+  244,  245,  246,  247,  248,  249,  250,  251,  252,  253,
+  254,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,  255,  255,  255,  255,  255,
+  255,  255,  255,  255,  255,
+};
+
+static const gshort floyd_steinberg_error1[] = {
+ -223, -223, -222, -222, -221, -221, -220, -220, -220, -219,
+ -219, -218, -218, -217, -217, -217, -216, -216, -215, -215,
+ -214, -214, -213, -213, -213, -212, -212, -211, -211, -210,
+ -210, -210, -209, -209, -208, -208, -207, -207, -206, -206,
+ -206, -205, -205, -204, -204, -203, -203, -203, -202, -202,
+ -201, -201, -200, -200, -199, -199, -199, -198, -198, -197,
+ -197, -196, -196, -196, -195, -195, -194, -194, -193, -193,
+ -192, -192, -192, -191, -191, -190, -190, -189, -189, -189,
+ -188, -188, -187, -187, -186, -186, -185, -185, -185, -184,
+ -184, -183, -183, -182, -182, -182, -181, -181, -180, -180,
+ -179, -179, -178, -178, -178, -177, -177, -176, -176, -175,
+ -175, -175, -174, -174, -173, -173, -172, -172, -171, -171,
+ -171, -170, -170, -169, -169, -168, -168, -168, -167, -167,
+ -166, -166, -165, -165, -164, -164, -164, -163, -163, -162,
+ -162, -161, -161, -161, -160, -160, -159, -159, -158, -158,
+ -157, -157, -157, -156, -156, -155, -155, -154, -154, -154,
+ -153, -153, -152, -152, -151, -151, -150, -150, -150, -149,
+ -149, -148, -148, -147, -147, -147, -146, -146, -145, -145,
+ -144, -144, -143, -143, -143, -142, -142, -141, -141, -140,
+ -140, -140, -139, -139, -138, -138, -137, -137, -136, -136,
+ -136, -135, -135, -134, -134, -133, -133, -133, -132, -132,
+ -131, -131, -130, -130, -129, -129, -129, -128, -128, -127,
+ -127, -126, -126, -126, -125, -125, -124, -124, -123, -123,
+ -122, -122, -122, -121, -121, -120, -120, -119, -119, -119,
+ -118, -118, -117, -117, -116, -116, -115, -115, -115, -114,
+ -114, -113, -113, -112, -112, -112, -111, -111, -110, -110,
+ -109, -109, -108, -108, -108, -107, -107, -106, -106, -105,
+ -105, -105, -104, -104, -103, -103, -102, -102, -101, -101,
+ -101, -100, -100,  -99,  -99,  -98,  -98,  -98,  -97,  -97,
+  -96,  -96,  -95,  -95,  -94,  -94,  -94,  -93,  -93,  -92,
+  -92,  -91,  -91,  -91,  -90,  -90,  -89,  -89,  -88,  -88,
+  -87,  -87,  -87,  -86,  -86,  -85,  -85,  -84,  -84,  -84,
+  -83,  -83,  -82,  -82,  -81,  -81,  -80,  -80,  -80,  -79,
+  -79,  -78,  -78,  -77,  -77,  -77,  -76,  -76,  -75,  -75,
+  -74,  -74,  -73,  -73,  -73,  -72,  -72,  -71,  -71,  -70,
+  -70,  -70,  -69,  -69,  -68,  -68,  -67,  -67,  -66,  -66,
+  -66,  -65,  -65,  -64,  -64,  -63,  -63,  -63,  -62,  -62,
+  -61,  -61,  -60,  -60,  -59,  -59,  -59,  -58,  -58,  -57,
+  -57,  -56,  -56,  -56,  -55,  -55,  -54,  -54,  -53,  -53,
+  -52,  -52,  -52,  -51,  -51,  -50,  -50,  -49,  -49,  -49,
+  -48,  -48,  -47,  -47,  -46,  -46,  -45,  -45,  -45,  -44,
+  -44,  -43,  -43,  -42,  -42,  -42,  -41,  -41,  -40,  -40,
+  -39,  -39,  -38,  -38,  -38,  -37,  -37,  -36,  -36,  -35,
+  -35,  -35,  -34,  -34,  -33,  -33,  -32,  -32,  -31,  -31,
+  -31,  -30,  -30,  -29,  -29,  -28,  -28,  -28,  -27,  -27,
+  -26,  -26,  -25,  -25,  -24,  -24,  -24,  -23,  -23,  -22,
+  -22,  -21,  -21,  -21,  -20,  -20,  -19,  -19,  -18,  -18,
+  -17,  -17,  -17,  -16,  -16,  -15,  -15,  -14,  -14,  -14,
+  -13,  -13,  -12,  -12,  -11,  -11,  -10,  -10,  -10,   -9,
+   -9,   -8,   -8,   -7,   -7,   -7,   -6,   -6,   -5,   -5,
+   -4,   -4,   -3,   -3,   -3,   -2,   -2,   -1,   -1,    0,
+    0,    0,    0,    0,    1,    1,    2,    2,    3,    3,
+    3,    4,    4,    5,    5,    6,    6,    7,    7,    7,
+    8,    8,    9,    9,   10,   10,   10,   11,   11,   12,
+   12,   13,   13,   14,   14,   14,   15,   15,   16,   16,
+   17,   17,   17,   18,   18,   19,   19,   20,   20,   21,
+   21,   21,   22,   22,   23,   23,   24,   24,   24,   25,
+   25,   26,   26,   27,   27,   28,   28,   28,   29,   29,
+   30,   30,   31,   31,   31,   32,   32,   33,   33,   34,
+   34,   35,   35,   35,   36,   36,   37,   37,   38,   38,
+   38,   39,   39,   40,   40,   41,   41,   42,   42,   42,
+   43,   43,   44,   44,   45,   45,   45,   46,   46,   47,
+   47,   48,   48,   49,   49,   49,   50,   50,   51,   51,
+   52,   52,   52,   53,   53,   54,   54,   55,   55,   56,
+   56,   56,   57,   57,   58,   58,   59,   59,   59,   60,
+   60,   61,   61,   62,   62,   63,   63,   63,   64,   64,
+   65,   65,   66,   66,   66,   67,   67,   68,   68,   69,
+   69,   70,   70,   70,   71,   71,   72,   72,   73,   73,
+   73,   74,   74,   75,   75,   76,   76,   77,   77,   77,
+   78,   78,   79,   79,   80,   80,   80,   81,   81,   82,
+   82,   83,   83,   84,   84,   84,   85,   85,   86,   86,
+   87,   87,   87,   88,   88,   89,   89,   90,   90,   91,
+   91,   91,   92,   92,   93,   93,   94,   94,   94,   95,
+   95,   96,   96,   97,   97,   98,   98,   98,   99,   99,
+  100,  100,  101,  101,  101,  102,  102,  103,  103,  104,
+  104,  105,  105,  105,  106,  106,  107,  107,  108,  108,
+  108,  109,  109,  110,  110,  111,  111,  112,  112,  112,
+  113,  113,  114,  114,  115,  115,  115,  116,  116,  117,
+  117,  118,  118,  119,  119,  119,  120,  120,  121,  121,
+  122,  122,  122,  123,  123,  124,  124,  125,  125,  126,
+  126,  126,  127,  127,  128,  128,  129,  129,  129,  130,
+  130,  131,  131,  132,  132,  133,  133,  133,  134,  134,
+  135,  135,  136,  136,  136,  137,  137,  138,  138,  139,
+  139,  140,  140,  140,  141,  141,  142,  142,  143,  143,
+  143,  144,  144,  145,  145,  146,  146,  147,  147,  147,
+  148,  148,  149,  149,  150,  150,  150,  151,  151,  152,
+  152,  153,  153,  154,  154,  154,  155,  155,  156,  156,
+  157,  157,  157,  158,  158,  159,  159,  160,  160,  161,
+  161,  161,  162,  162,  163,  163,  164,  164,  164,  165,
+  165,  166,  166,  167,  167,  168,  168,  168,  169,  169,
+  170,  170,  171,  171,  171,  172,  172,  173,  173,  174,
+  174,  175,  175,  175,  176,  176,  177,  177,  178,  178,
+  178,  179,  179,  180,  180,  181,  181,  182,  182,  182,
+  183,  183,  184,  184,  185,  185,  185,  186,  186,  187,
+  187,  188,  188,  189,  189,  189,  190,  190,  191,  191,
+  192,  192,  192,  193,  193,  194,  194,  195,  195,  196,
+  196,  196,  197,  197,  198,  198,  199,  199,  199,  200,
+  200,  201,  201,  202,  202,  203,  203,  203,  204,  204,
+  205,  205,  206,  206,  206,  207,  207,  208,  208,  209,
+  209,  210,  210,  210,  211,  211,  212,  212,  213,  213,
+  213,  214,  214,  215,  215,  216,  216,  217,  217,  217,
+  218,  218,  219,  219,  220,  220,  220,  221,  221,  222,
+  222,  223,  223,  224,  224,
+};
+
+static const gshort floyd_steinberg_error2[] = {
+  -95,  -95,  -95,  -95,  -95,  -94,  -94,  -94,  -94,  -94,
+  -93,  -93,  -93,  -93,  -93,  -93,  -92,  -92,  -92,  -92,
+  -92,  -91,  -91,  -91,  -91,  -91,  -90,  -90,  -90,  -90,
+  -90,  -90,  -89,  -89,  -89,  -89,  -89,  -88,  -88,  -88,
+  -88,  -88,  -87,  -87,  -87,  -87,  -87,  -87,  -86,  -86,
+  -86,  -86,  -86,  -85,  -85,  -85,  -85,  -85,  -84,  -84,
+  -84,  -84,  -84,  -84,  -83,  -83,  -83,  -83,  -83,  -82,
+  -82,  -82,  -82,  -82,  -81,  -81,  -81,  -81,  -81,  -81,
+  -80,  -80,  -80,  -80,  -80,  -79,  -79,  -79,  -79,  -79,
+  -78,  -78,  -78,  -78,  -78,  -78,  -77,  -77,  -77,  -77,
+  -77,  -76,  -76,  -76,  -76,  -76,  -75,  -75,  -75,  -75,
+  -75,  -75,  -74,  -74,  -74,  -74,  -74,  -73,  -73,  -73,
+  -73,  -73,  -72,  -72,  -72,  -72,  -72,  -72,  -71,  -71,
+  -71,  -71,  -71,  -70,  -70,  -70,  -70,  -70,  -69,  -69,
+  -69,  -69,  -69,  -69,  -68,  -68,  -68,  -68,  -68,  -67,
+  -67,  -67,  -67,  -67,  -66,  -66,  -66,  -66,  -66,  -66,
+  -65,  -65,  -65,  -65,  -65,  -64,  -64,  -64,  -64,  -64,
+  -63,  -63,  -63,  -63,  -63,  -63,  -62,  -62,  -62,  -62,
+  -62,  -61,  -61,  -61,  -61,  -61,  -60,  -60,  -60,  -60,
+  -60,  -60,  -59,  -59,  -59,  -59,  -59,  -58,  -58,  -58,
+  -58,  -58,  -57,  -57,  -57,  -57,  -57,  -57,  -56,  -56,
+  -56,  -56,  -56,  -55,  -55,  -55,  -55,  -55,  -54,  -54,
+  -54,  -54,  -54,  -54,  -53,  -53,  -53,  -53,  -53,  -52,
+  -52,  -52,  -52,  -52,  -51,  -51,  -51,  -51,  -51,  -51,
+  -50,  -50,  -50,  -50,  -50,  -49,  -49,  -49,  -49,  -49,
+  -48,  -48,  -48,  -48,  -48,  -48,  -47,  -47,  -47,  -47,
+  -47,  -46,  -46,  -46,  -46,  -46,  -45,  -45,  -45,  -45,
+  -45,  -45,  -44,  -44,  -44,  -44,  -44,  -43,  -43,  -43,
+  -43,  -43,  -42,  -42,  -42,  -42,  -42,  -42,  -41,  -41,
+  -41,  -41,  -41,  -40,  -40,  -40,  -40,  -40,  -39,  -39,
+  -39,  -39,  -39,  -39,  -38,  -38,  -38,  -38,  -38,  -37,
+  -37,  -37,  -37,  -37,  -36,  -36,  -36,  -36,  -36,  -36,
+  -35,  -35,  -35,  -35,  -35,  -34,  -34,  -34,  -34,  -34,
+  -33,  -33,  -33,  -33,  -33,  -33,  -32,  -32,  -32,  -32,
+  -32,  -31,  -31,  -31,  -31,  -31,  -30,  -30,  -30,  -30,
+  -30,  -30,  -29,  -29,  -29,  -29,  -29,  -28,  -28,  -28,
+  -28,  -28,  -27,  -27,  -27,  -27,  -27,  -27,  -26,  -26,
+  -26,  -26,  -26,  -25,  -25,  -25,  -25,  -25,  -24,  -24,
+  -24,  -24,  -24,  -24,  -23,  -23,  -23,  -23,  -23,  -22,
+  -22,  -22,  -22,  -22,  -21,  -21,  -21,  -21,  -21,  -21,
+  -20,  -20,  -20,  -20,  -20,  -19,  -19,  -19,  -19,  -19,
+  -18,  -18,  -18,  -18,  -18,  -18,  -17,  -17,  -17,  -17,
+  -17,  -16,  -16,  -16,  -16,  -16,  -15,  -15,  -15,  -15,
+  -15,  -15,  -14,  -14,  -14,  -14,  -14,  -13,  -13,  -13,
+  -13,  -13,  -12,  -12,  -12,  -12,  -12,  -12,  -11,  -11,
+  -11,  -11,  -11,  -10,  -10,  -10,  -10,  -10,   -9,   -9,
+   -9,   -9,   -9,   -9,   -8,   -8,   -8,   -8,   -8,   -7,
+   -7,   -7,   -7,   -7,   -6,   -6,   -6,   -6,   -6,   -6,
+   -5,   -5,   -5,   -5,   -5,   -4,   -4,   -4,   -4,   -4,
+   -3,   -3,   -3,   -3,   -3,   -3,   -2,   -2,   -2,   -2,
+   -2,   -1,   -1,   -1,   -1,   -1,    0,    0,    0,    0,
+    0,    0,    0,    0,    0,    0,    0,    1,    1,    1,
+    1,    1,    2,    2,    2,    2,    2,    3,    3,    3,
+    3,    3,    3,    4,    4,    4,    4,    4,    5,    5,
+    5,    5,    5,    6,    6,    6,    6,    6,    6,    7,
+    7,    7,    7,    7,    8,    8,    8,    8,    8,    9,
+    9,    9,    9,    9,    9,   10,   10,   10,   10,   10,
+   11,   11,   11,   11,   11,   12,   12,   12,   12,   12,
+   12,   13,   13,   13,   13,   13,   14,   14,   14,   14,
+   14,   15,   15,   15,   15,   15,   15,   16,   16,   16,
+   16,   16,   17,   17,   17,   17,   17,   18,   18,   18,
+   18,   18,   18,   19,   19,   19,   19,   19,   20,   20,
+   20,   20,   20,   21,   21,   21,   21,   21,   21,   22,
+   22,   22,   22,   22,   23,   23,   23,   23,   23,   24,
+   24,   24,   24,   24,   24,   25,   25,   25,   25,   25,
+   26,   26,   26,   26,   26,   27,   27,   27,   27,   27,
+   27,   28,   28,   28,   28,   28,   29,   29,   29,   29,
+   29,   30,   30,   30,   30,   30,   30,   31,   31,   31,
+   31,   31,   32,   32,   32,   32,   32,   33,   33,   33,
+   33,   33,   33,   34,   34,   34,   34,   34,   35,   35,
+   35,   35,   35,   36,   36,   36,   36,   36,   36,   37,
+   37,   37,   37,   37,   38,   38,   38,   38,   38,   39,
+   39,   39,   39,   39,   39,   40,   40,   40,   40,   40,
+   41,   41,   41,   41,   41,   42,   42,   42,   42,   42,
+   42,   43,   43,   43,   43,   43,   44,   44,   44,   44,
+   44,   45,   45,   45,   45,   45,   45,   46,   46,   46,
+   46,   46,   47,   47,   47,   47,   47,   48,   48,   48,
+   48,   48,   48,   49,   49,   49,   49,   49,   50,   50,
+   50,   50,   50,   51,   51,   51,   51,   51,   51,   52,
+   52,   52,   52,   52,   53,   53,   53,   53,   53,   54,
+   54,   54,   54,   54,   54,   55,   55,   55,   55,   55,
+   56,   56,   56,   56,   56,   57,   57,   57,   57,   57,
+   57,   58,   58,   58,   58,   58,   59,   59,   59,   59,
+   59,   60,   60,   60,   60,   60,   60,   61,   61,   61,
+   61,   61,   62,   62,   62,   62,   62,   63,   63,   63,
+   63,   63,   63,   64,   64,   64,   64,   64,   65,   65,
+   65,   65,   65,   66,   66,   66,   66,   66,   66,   67,
+   67,   67,   67,   67,   68,   68,   68,   68,   68,   69,
+   69,   69,   69,   69,   69,   70,   70,   70,   70,   70,
+   71,   71,   71,   71,   71,   72,   72,   72,   72,   72,
+   72,   73,   73,   73,   73,   73,   74,   74,   74,   74,
+   74,   75,   75,   75,   75,   75,   75,   76,   76,   76,
+   76,   76,   77,   77,   77,   77,   77,   78,   78,   78,
+   78,   78,   78,   79,   79,   79,   79,   79,   80,   80,
+   80,   80,   80,   81,   81,   81,   81,   81,   81,   82,
+   82,   82,   82,   82,   83,   83,   83,   83,   83,   84,
+   84,   84,   84,   84,   84,   85,   85,   85,   85,   85,
+   86,   86,   86,   86,   86,   87,   87,   87,   87,   87,
+   87,   88,   88,   88,   88,   88,   89,   89,   89,   89,
+   89,   90,   90,   90,   90,   90,   90,   91,   91,   91,
+   91,   91,   92,   92,   92,   92,   92,   93,   93,   93,
+   93,   93,   93,   94,   94,   94,   94,   94,   95,   95,
+   95,   95,   95,   96,   96,
+};
+
+static const gshort floyd_steinberg_error3[] = {
+ -159, -159, -159, -158, -158, -158, -157, -157, -157, -156,
+ -156, -156, -155, -155, -155, -155, -154, -154, -154, -153,
+ -153, -153, -152, -152, -152, -151, -151, -151, -150, -150,
+ -150, -150, -149, -149, -149, -148, -148, -148, -147, -147,
+ -147, -146, -146, -146, -145, -145, -145, -145, -144, -144,
+ -144, -143, -143, -143, -142, -142, -142, -141, -141, -141,
+ -140, -140, -140, -140, -139, -139, -139, -138, -138, -138,
+ -137, -137, -137, -136, -136, -136, -135, -135, -135, -135,
+ -134, -134, -134, -133, -133, -133, -132, -132, -132, -131,
+ -131, -131, -130, -130, -130, -130, -129, -129, -129, -128,
+ -128, -128, -127, -127, -127, -126, -126, -126, -125, -125,
+ -125, -125, -124, -124, -124, -123, -123, -123, -122, -122,
+ -122, -121, -121, -121, -120, -120, -120, -120, -119, -119,
+ -119, -118, -118, -118, -117, -117, -117, -116, -116, -116,
+ -115, -115, -115, -115, -114, -114, -114, -113, -113, -113,
+ -112, -112, -112, -111, -111, -111, -110, -110, -110, -110,
+ -109, -109, -109, -108, -108, -108, -107, -107, -107, -106,
+ -106, -106, -105, -105, -105, -105, -104, -104, -104, -103,
+ -103, -103, -102, -102, -102, -101, -101, -101, -100, -100,
+ -100, -100,  -99,  -99,  -99,  -98,  -98,  -98,  -97,  -97,
+  -97,  -96,  -96,  -96,  -95,  -95,  -95,  -95,  -94,  -94,
+  -94,  -93,  -93,  -93,  -92,  -92,  -92,  -91,  -91,  -91,
+  -90,  -90,  -90,  -90,  -89,  -89,  -89,  -88,  -88,  -88,
+  -87,  -87,  -87,  -86,  -86,  -86,  -85,  -85,  -85,  -85,
+  -84,  -84,  -84,  -83,  -83,  -83,  -82,  -82,  -82,  -81,
+  -81,  -81,  -80,  -80,  -80,  -80,  -79,  -79,  -79,  -78,
+  -78,  -78,  -77,  -77,  -77,  -76,  -76,  -76,  -75,  -75,
+  -75,  -75,  -74,  -74,  -74,  -73,  -73,  -73,  -72,  -72,
+  -72,  -71,  -71,  -71,  -70,  -70,  -70,  -70,  -69,  -69,
+  -69,  -68,  -68,  -68,  -67,  -67,  -67,  -66,  -66,  -66,
+  -65,  -65,  -65,  -65,  -64,  -64,  -64,  -63,  -63,  -63,
+  -62,  -62,  -62,  -61,  -61,  -61,  -60,  -60,  -60,  -60,
+  -59,  -59,  -59,  -58,  -58,  -58,  -57,  -57,  -57,  -56,
+  -56,  -56,  -55,  -55,  -55,  -55,  -54,  -54,  -54,  -53,
+  -53,  -53,  -52,  -52,  -52,  -51,  -51,  -51,  -50,  -50,
+  -50,  -50,  -49,  -49,  -49,  -48,  -48,  -48,  -47,  -47,
+  -47,  -46,  -46,  -46,  -45,  -45,  -45,  -45,  -44,  -44,
+  -44,  -43,  -43,  -43,  -42,  -42,  -42,  -41,  -41,  -41,
+  -40,  -40,  -40,  -40,  -39,  -39,  -39,  -38,  -38,  -38,
+  -37,  -37,  -37,  -36,  -36,  -36,  -35,  -35,  -35,  -35,
+  -34,  -34,  -34,  -33,  -33,  -33,  -32,  -32,  -32,  -31,
+  -31,  -31,  -30,  -30,  -30,  -30,  -29,  -29,  -29,  -28,
+  -28,  -28,  -27,  -27,  -27,  -26,  -26,  -26,  -25,  -25,
+  -25,  -25,  -24,  -24,  -24,  -23,  -23,  -23,  -22,  -22,
+  -22,  -21,  -21,  -21,  -20,  -20,  -20,  -20,  -19,  -19,
+  -19,  -18,  -18,  -18,  -17,  -17,  -17,  -16,  -16,  -16,
+  -15,  -15,  -15,  -15,  -14,  -14,  -14,  -13,  -13,  -13,
+  -12,  -12,  -12,  -11,  -11,  -11,  -10,  -10,  -10,  -10,
+   -9,   -9,   -9,   -8,   -8,   -8,   -7,   -7,   -7,   -6,
+   -6,   -6,   -5,   -5,   -5,   -5,   -4,   -4,   -4,   -3,
+   -3,   -3,   -2,   -2,   -2,   -1,   -1,   -1,    0,    0,
+    0,    0,    0,    0,    0,    1,    1,    1,    2,    2,
+    2,    3,    3,    3,    4,    4,    4,    5,    5,    5,
+    5,    6,    6,    6,    7,    7,    7,    8,    8,    8,
+    9,    9,    9,   10,   10,   10,   10,   11,   11,   11,
+   12,   12,   12,   13,   13,   13,   14,   14,   14,   15,
+   15,   15,   15,   16,   16,   16,   17,   17,   17,   18,
+   18,   18,   19,   19,   19,   20,   20,   20,   20,   21,
+   21,   21,   22,   22,   22,   23,   23,   23,   24,   24,
+   24,   25,   25,   25,   25,   26,   26,   26,   27,   27,
+   27,   28,   28,   28,   29,   29,   29,   30,   30,   30,
+   30,   31,   31,   31,   32,   32,   32,   33,   33,   33,
+   34,   34,   34,   35,   35,   35,   35,   36,   36,   36,
+   37,   37,   37,   38,   38,   38,   39,   39,   39,   40,
+   40,   40,   40,   41,   41,   41,   42,   42,   42,   43,
+   43,   43,   44,   44,   44,   45,   45,   45,   45,   46,
+   46,   46,   47,   47,   47,   48,   48,   48,   49,   49,
+   49,   50,   50,   50,   50,   51,   51,   51,   52,   52,
+   52,   53,   53,   53,   54,   54,   54,   55,   55,   55,
+   55,   56,   56,   56,   57,   57,   57,   58,   58,   58,
+   59,   59,   59,   60,   60,   60,   60,   61,   61,   61,
+   62,   62,   62,   63,   63,   63,   64,   64,   64,   65,
+   65,   65,   65,   66,   66,   66,   67,   67,   67,   68,
+   68,   68,   69,   69,   69,   70,   70,   70,   70,   71,
+   71,   71,   72,   72,   72,   73,   73,   73,   74,   74,
+   74,   75,   75,   75,   75,   76,   76,   76,   77,   77,
+   77,   78,   78,   78,   79,   79,   79,   80,   80,   80,
+   80,   81,   81,   81,   82,   82,   82,   83,   83,   83,
+   84,   84,   84,   85,   85,   85,   85,   86,   86,   86,
+   87,   87,   87,   88,   88,   88,   89,   89,   89,   90,
+   90,   90,   90,   91,   91,   91,   92,   92,   92,   93,
+   93,   93,   94,   94,   94,   95,   95,   95,   95,   96,
+   96,   96,   97,   97,   97,   98,   98,   98,   99,   99,
+   99,  100,  100,  100,  100,  101,  101,  101,  102,  102,
+  102,  103,  103,  103,  104,  104,  104,  105,  105,  105,
+  105,  106,  106,  106,  107,  107,  107,  108,  108,  108,
+  109,  109,  109,  110,  110,  110,  110,  111,  111,  111,
+  112,  112,  112,  113,  113,  113,  114,  114,  114,  115,
+  115,  115,  115,  116,  116,  116,  117,  117,  117,  118,
+  118,  118,  119,  119,  119,  120,  120,  120,  120,  121,
+  121,  121,  122,  122,  122,  123,  123,  123,  124,  124,
+  124,  125,  125,  125,  125,  126,  126,  126,  127,  127,
+  127,  128,  128,  128,  129,  129,  129,  130,  130,  130,
+  130,  131,  131,  131,  132,  132,  132,  133,  133,  133,
+  134,  134,  134,  135,  135,  135,  135,  136,  136,  136,
+  137,  137,  137,  138,  138,  138,  139,  139,  139,  140,
+  140,  140,  140,  141,  141,  141,  142,  142,  142,  143,
+  143,  143,  144,  144,  144,  145,  145,  145,  145,  146,
+  146,  146,  147,  147,  147,  148,  148,  148,  149,  149,
+  149,  150,  150,  150,  150,  151,  151,  151,  152,  152,
+  152,  153,  153,  153,  154,  154,  154,  155,  155,  155,
+  155,  156,  156,  156,  157,  157,  157,  158,  158,  158,
+  159,  159,  159,  160,  160,
+};
+
+static const gshort floyd_steinberg_error4[] = {
+  -34,  -33,  -33,  -33,  -33,  -33,  -34,  -33,  -32,  -33,
+  -33,  -33,  -33,  -33,  -32,  -31,  -33,  -32,  -32,  -32,
+  -32,  -32,  -33,  -32,  -31,  -32,  -32,  -32,  -32,  -32,
+  -31,  -30,  -32,  -31,  -31,  -31,  -31,  -31,  -32,  -31,
+  -30,  -31,  -31,  -31,  -31,  -31,  -30,  -29,  -31,  -30,
+  -30,  -30,  -30,  -30,  -31,  -30,  -29,  -30,  -30,  -30,
+  -30,  -30,  -29,  -28,  -30,  -29,  -29,  -29,  -29,  -29,
+  -30,  -29,  -28,  -29,  -29,  -29,  -29,  -29,  -28,  -27,
+  -29,  -28,  -28,  -28,  -28,  -28,  -29,  -28,  -27,  -28,
+  -28,  -28,  -28,  -28,  -27,  -26,  -28,  -27,  -27,  -27,
+  -27,  -27,  -28,  -27,  -26,  -27,  -27,  -27,  -27,  -27,
+  -26,  -25,  -27,  -26,  -26,  -26,  -26,  -26,  -27,  -26,
+  -25,  -26,  -26,  -26,  -26,  -26,  -25,  -24,  -26,  -25,
+  -25,  -25,  -25,  -25,  -26,  -25,  -24,  -25,  -25,  -25,
+  -25,  -25,  -24,  -23,  -25,  -24,  -24,  -24,  -24,  -24,
+  -25,  -24,  -23,  -24,  -24,  -24,  -24,  -24,  -23,  -22,
+  -24,  -23,  -23,  -23,  -23,  -23,  -24,  -23,  -22,  -23,
+  -23,  -23,  -23,  -23,  -22,  -21,  -23,  -22,  -22,  -22,
+  -22,  -22,  -23,  -22,  -21,  -22,  -22,  -22,  -22,  -22,
+  -21,  -20,  -22,  -21,  -21,  -21,  -21,  -21,  -22,  -21,
+  -20,  -21,  -21,  -21,  -21,  -21,  -20,  -19,  -21,  -20,
+  -20,  -20,  -20,  -20,  -21,  -20,  -19,  -20,  -20,  -20,
+  -20,  -20,  -19,  -18,  -20,  -19,  -19,  -19,  -19,  -19,
+  -20,  -19,  -18,  -19,  -19,  -19,  -19,  -19,  -18,  -17,
+  -19,  -18,  -18,  -18,  -18,  -18,  -19,  -18,  -17,  -18,
+  -18,  -18,  -18,  -18,  -17,  -16,  -18,  -17,  -17,  -17,
+  -17,  -17,  -18,  -17,  -16,  -17,  -17,  -17,  -17,  -17,
+  -16,  -15,  -17,  -16,  -16,  -16,  -16,  -16,  -17,  -16,
+  -15,  -16,  -16,  -16,  -16,  -16,  -15,  -14,  -16,  -15,
+  -15,  -15,  -15,  -15,  -16,  -15,  -14,  -15,  -15,  -15,
+  -15,  -15,  -14,  -13,  -15,  -14,  -14,  -14,  -14,  -14,
+  -15,  -14,  -13,  -14,  -14,  -14,  -14,  -14,  -13,  -12,
+  -14,  -13,  -13,  -13,  -13,  -13,  -14,  -13,  -12,  -13,
+  -13,  -13,  -13,  -13,  -12,  -11,  -13,  -12,  -12,  -12,
+  -12,  -12,  -13,  -12,  -11,  -12,  -12,  -12,  -12,  -12,
+  -11,  -10,  -12,  -11,  -11,  -11,  -11,  -11,  -12,  -11,
+  -10,  -11,  -11,  -11,  -11,  -11,  -10,   -9,  -11,  -10,
+  -10,  -10,  -10,  -10,  -11,  -10,   -9,  -10,  -10,  -10,
+  -10,  -10,   -9,   -8,  -10,   -9,   -9,   -9,   -9,   -9,
+  -10,   -9,   -8,   -9,   -9,   -9,   -9,   -9,   -8,   -7,
+   -9,   -8,   -8,   -8,   -8,   -8,   -9,   -8,   -7,   -8,
+   -8,   -8,   -8,   -8,   -7,   -6,   -8,   -7,   -7,   -7,
+   -7,   -7,   -8,   -7,   -6,   -7,   -7,   -7,   -7,   -7,
+   -6,   -5,   -7,   -6,   -6,   -6,   -6,   -6,   -7,   -6,
+   -5,   -6,   -6,   -6,   -6,   -6,   -5,   -4,   -6,   -5,
+   -5,   -5,   -5,   -5,   -6,   -5,   -4,   -5,   -5,   -5,
+   -5,   -5,   -4,   -3,   -5,   -4,   -4,   -4,   -4,   -4,
+   -5,   -4,   -3,   -4,   -4,   -4,   -4,   -4,   -3,   -2,
+   -4,   -3,   -3,   -3,   -3,   -3,   -4,   -3,   -2,   -3,
+   -3,   -3,   -3,   -3,   -2,   -1,   -3,   -2,   -2,   -2,
+   -2,   -2,   -3,   -2,   -1,   -2,   -2,   -2,   -2,   -2,
+   -1,    0,    1,    2,    2,    2,    2,    2,    1,    2,
+    3,    2,    2,    2,    2,    2,    3,    1,    2,    3,
+    3,    3,    3,    3,    2,    3,    4,    3,    3,    3,
+    3,    3,    4,    2,    3,    4,    4,    4,    4,    4,
+    3,    4,    5,    4,    4,    4,    4,    4,    5,    3,
+    4,    5,    5,    5,    5,    5,    4,    5,    6,    5,
+    5,    5,    5,    5,    6,    4,    5,    6,    6,    6,
+    6,    6,    5,    6,    7,    6,    6,    6,    6,    6,
+    7,    5,    6,    7,    7,    7,    7,    7,    6,    7,
+    8,    7,    7,    7,    7,    7,    8,    6,    7,    8,
+    8,    8,    8,    8,    7,    8,    9,    8,    8,    8,
+    8,    8,    9,    7,    8,    9,    9,    9,    9,    9,
+    8,    9,   10,    9,    9,    9,    9,    9,   10,    8,
+    9,   10,   10,   10,   10,   10,    9,   10,   11,   10,
+   10,   10,   10,   10,   11,    9,   10,   11,   11,   11,
+   11,   11,   10,   11,   12,   11,   11,   11,   11,   11,
+   12,   10,   11,   12,   12,   12,   12,   12,   11,   12,
+   13,   12,   12,   12,   12,   12,   13,   11,   12,   13,
+   13,   13,   13,   13,   12,   13,   14,   13,   13,   13,
+   13,   13,   14,   12,   13,   14,   14,   14,   14,   14,
+   13,   14,   15,   14,   14,   14,   14,   14,   15,   13,
+   14,   15,   15,   15,   15,   15,   14,   15,   16,   15,
+   15,   15,   15,   15,   16,   14,   15,   16,   16,   16,
+   16,   16,   15,   16,   17,   16,   16,   16,   16,   16,
+   17,   15,   16,   17,   17,   17,   17,   17,   16,   17,
+   18,   17,   17,   17,   17,   17,   18,   16,   17,   18,
+   18,   18,   18,   18,   17,   18,   19,   18,   18,   18,
+   18,   18,   19,   17,   18,   19,   19,   19,   19,   19,
+   18,   19,   20,   19,   19,   19,   19,   19,   20,   18,
+   19,   20,   20,   20,   20,   20,   19,   20,   21,   20,
+   20,   20,   20,   20,   21,   19,   20,   21,   21,   21,
+   21,   21,   20,   21,   22,   21,   21,   21,   21,   21,
+   22,   20,   21,   22,   22,   22,   22,   22,   21,   22,
+   23,   22,   22,   22,   22,   22,   23,   21,   22,   23,
+   23,   23,   23,   23,   22,   23,   24,   23,   23,   23,
+   23,   23,   24,   22,   23,   24,   24,   24,   24,   24,
+   23,   24,   25,   24,   24,   24,   24,   24,   25,   23,
+   24,   25,   25,   25,   25,   25,   24,   25,   26,   25,
+   25,   25,   25,   25,   26,   24,   25,   26,   26,   26,
+   26,   26,   25,   26,   27,   26,   26,   26,   26,   26,
+   27,   25,   26,   27,   27,   27,   27,   27,   26,   27,
+   28,   27,   27,   27,   27,   27,   28,   26,   27,   28,
+   28,   28,   28,   28,   27,   28,   29,   28,   28,   28,
+   28,   28,   29,   27,   28,   29,   29,   29,   29,   29,
+   28,   29,   30,   29,   29,   29,   29,   29,   30,   28,
+   29,   30,   30,   30,   30,   30,   29,   30,   31,   30,
+   30,   30,   30,   30,   31,   29,   30,   31,   31,   31,
+   31,   31,   30,   31,   32,   31,   31,   31,   31,   31,
+   32,   30,   31,   32,   32,   32,   32,   32,   31,   32,
+   33,   32,   32,   32,   32,   32,   33,   31,   32,   33,
+   33,   33,   33,   33,   32,   33,   34,   33,   33,   33,
+   33,   33,   34,   32,   33,
+};
+
+#endif /* __GIMP_IMAGE_CONVERT_FSDITHER_H__ */
diff --git a/app/core/gimpimage-convert-indexed.c b/app/core/gimpimage-convert-indexed.c
new file mode 100644
index 0000000..6a3eae3
--- /dev/null
+++ b/app/core/gimpimage-convert-indexed.c
@@ -0,0 +1,4567 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpimage-convert-indexed.c
+ * Copyright (C) 1997-2004 Adam D. Moss <adam@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/*
+ * 2005-09-04 - Switch 'positional' dither matrix to a 32x32 Bayer,
+ *  which generates results that compress somewhat better (and may look
+ *  worse or better depending on what you enjoy...).  [adam@gimp.org]
+ *
+ * 2004-12-12 - Use a slower but much nicer technique for finding the
+ *  two best colors to dither between when using fixed/positional
+ *  dither methods.  Makes positional dither much less lame.  [adam@gimp.org]
+ *
+ * 2002-02-10 - Quantizer version 3.0 (the rest of the commit started
+ *  a year ago -- whoops).  Divide colors within CIE L*a*b* space using
+ *  CPercep module (cpercep.[ch]), color-match and dither likewise,
+ *  change the underlying box selection criteria and division point
+ *  logic, bump luminance precision upwards, etc.etc.  Generally
+ *  chooses a much richer color set, especially for low numbers of
+ *  colors.  n.b.: Less luminance-sloppy in straight remapping which is
+ *  good for color but a bit worse for high-frequency detail (that's
+ *  partly what fs-dithering is for -- use it).  [adam@gimp.org]
+ *
+ * 2001-03-25 - Define accessor function/macro for histogram reads and
+ *  writes.  This slows us down a little because we avoid some of the
+ *  dirty tricks we used when we knew that the histogram was a straight
+ *  3d array, so I've recovered some of the speed loss by implementing
+ *  a 5d accessor function with good locality of reference.  This change
+ *  is the first step towards quantizing in a more interesting colorspace
+ *  than frumpy old RGB.  [Adam]
+ *
+ * 2000/01/30 - Use palette_selector instead of option_menu for custom
+ *  palette. Use libgimp callback functions.  [Sven]
+ *
+ * 99/09/01 - Created a low-bleed FS-dither option.  [Adam]
+ *
+ * 99/08/29 - Deterministic color dithering to arbitrary palettes.
+ *  Ideal for animations that are going to be delta-optimized or simply
+ *  don't want to look 'busy' in static areas.  Also a bunch of bugfixes
+ *  and tweaks.  [Adam]
+ *
+ * 99/08/28 - Deterministic alpha dithering over layers, reduced bleeding
+ *  of transparent values into opaque values, added optional stage to
+ *  remove duplicate or unused color entries from final colormap. [Adam]
+ *
+ * 99/02/24 - Many revisions to the box-cut quantizer used in RGB->INDEXED
+ *  conversion.  Box to be cut is chosen on the basis of possessing an axis
+ *  with the largest sum of weighted perceptible error, rather than based on
+ *  volume or population.  The box is split along this axis rather than its
+ *  longest axis, at the point of error mean rather than simply at its centre.
+ *  Error-limiting in the F-S dither has been disabled - it may become optional
+ *  again later.  If you're convinced that you have an image where the old
+ *  dither looks better, let me know.  [Adam]
+ *
+ * 99/01/10 - Hourglass... [Adam]
+ *
+ * 98/07/25 - Convert-to-indexed now remembers the last invocation's
+ *  settings.  Also, GRAY->INDEXED is more flexible.  [Adam]
+ *
+ * 98/07/05 - Sucked the warning about quantizing to too many colors into
+ *  a text widget embedded in the dialog, improved intelligence of dialog
+ *  to default 'custom palette' selection to 'Web' if available, and
+ *  in this case not bother to present the native WWW-palette radio
+ *  button.  [Adam]
+ *
+ * 98/04/13 - avoid a division by zero when converting an empty gray-scale
+ *  image (who would like to do such a thing anyway??)  [Sven ]
+ *
+ * 98/03/23 - fixed a longstanding fencepost - hopefully the *right*
+ *  way, *again*.  [Adam]
+ *
+ * 97/11/14 - added a proper pdb interface and support for dithering
+ *  to custom palettes (based on a patch by Eric Hernes) [Yosh]
+ *
+ * 97/11/04 - fixed the accidental use of the color-counting case
+ *  when palette_type is WEB or MONO. [Adam]
+ *
+ * 97/10/25 - color-counting implemented (could use some hashing, but
+ *  performance actually seems okay) - now RGB->INDEXED conversion isn't
+ *  destructive if it doesn't have to be. [Adam]
+ *
+ * 97/10/14 - fixed divide-by-zero when converting a completely transparent
+ *  RGB image to indexed. [Adam]
+ *
+ * 97/07/01 - started todo/revision log.  Put code back in to
+ *  eliminate full-alpha pixels from RGB histogram.
+ *  [Adam D. Moss - adam@gimp.org]
+ */
+
+  /* TODO for Convert:
+   *
+   * . Tweak, tweak, tweak.  Old RGB code was tuned muchly.
+   *
+   * . Re-enable Heckbert locality for matching, benchmark it
+   *
+   * . Try faster fixed-point sRGB<->L*a*b* pixel conversion (see cpercep.c)
+   *
+   * . Use palette of another open INDEXED image?
+   *
+   * . Do error-splitting trick for GREY->INDEXED (hardly worth it)
+   */
+
+  /* CODE READABILITY BUGS:
+   *
+   * . Most uses of variants of the R,G,B variable naming convention
+   *   are referring to L*a*b* co-ordinates, not RGB co-ordinates!
+   *
+   * . Each said variable is usually one of the following, but it is
+   *   rarely clear which one:
+   *     - (assumed sRGB) raw non-linear 8-bit RGB co-ordinates
+   *     - 'full'-precision (unshifted) 8-bit L*a*b* co-ordinates
+   *     - box-space (reduced-precision shifted L*a*b*) co-ordinates
+   */
+
+#include "config.h"
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+#include <cairo.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpcolor/gimpcolor.h"
+#include "libgimpmath/gimpmath.h"
+
+#include "core-types.h"
+
+#include "gegl/gimp-babl.h"
+#include "gegl/gimp-gegl-utils.h"
+
+#include "gimp.h"
+#include "gimpcontainer.h"
+#include "gimpdrawable.h"
+#include "gimperror.h"
+#include "gimpimage.h"
+#include "gimpimage-color-profile.h"
+#include "gimpimage-colormap.h"
+#include "gimpimage-undo.h"
+#include "gimpimage-undo-push.h"
+#include "gimplayer.h"
+#include "gimpobjectqueue.h"
+#include "gimppalette.h"
+#include "gimpprogress.h"
+
+#include "text/gimptextlayer.h"
+
+#include "gimpimage-convert-fsdither.h"
+#include "gimpimage-convert-data.h"
+#include "gimpimage-convert-indexed.h"
+
+#include "gimp-intl.h"
+
+
+/* basic memory/quality tradeoff */
+#define PRECISION_R 8
+#define PRECISION_G 6
+#define PRECISION_B 6
+
+#define HIST_R_ELEMS (1<<PRECISION_R)
+#define HIST_G_ELEMS (1<<PRECISION_G)
+#define HIST_B_ELEMS (1<<PRECISION_B)
+
+#define BITS_IN_SAMPLE 8
+
+#define R_SHIFT  (BITS_IN_SAMPLE-PRECISION_R)
+#define G_SHIFT  (BITS_IN_SAMPLE-PRECISION_G)
+#define B_SHIFT  (BITS_IN_SAMPLE-PRECISION_B)
+
+/* we've stretched our non-cubic L*a*b* volume to touch the
+ * faces of the logical cube we've allocated for it, so re-scale
+ * again in inverse proportion to get back to linear proportions.
+ */
+#define R_SCALE 13              /*  scale R (L*) distances by this much  */
+#define G_SCALE 24              /*  scale G (a*) distances by this much  */
+#define B_SCALE 26              /*  and B (b*) by this much              */
+
+
+typedef struct _Color Color;
+typedef struct _QuantizeObj QuantizeObj;
+
+typedef void (* Pass1Func)     (QuantizeObj *quantize_obj);
+typedef void (* Pass2InitFunc) (QuantizeObj *quantize_obj);
+typedef void (* Pass2Func)     (QuantizeObj *quantize_obj,
+                                GimpLayer   *layer,
+                                GeglBuffer  *new_buffer);
+typedef void (* CleanupFunc)   (QuantizeObj *quantize_obj);
+
+typedef guint64 ColorFreq;
+typedef ColorFreq * CFHistogram;
+
+typedef enum { AXIS_UNDEF, AXIS_RED, AXIS_BLUE, AXIS_GREEN } AxisType;
+
+typedef double etype;
+
+
+/*
+  We provide two different histogram access interfaces.  HIST_LIN()
+  accesses the histogram in histogram-native space, taking absolute
+  histogram co-ordinates.  HIST_RGB() accesses the histogram in RGB
+  space.  This latter takes unsigned 8-bit co-ordinates, internally
+  converts those co-ordinates to histogram-native space and returns
+  the access pointer to the corresponding histogram cell.
+
+  Using these two interfaces we can import RGB data into a more
+  interesting space and efficiently work in the latter space until
+  it is time to output the quantized values in RGB again.  For
+  this final conversion we implement the function lin_to_rgb().
+
+  We effectively pull our three-dimensional space into five dimensions
+  such that the most-entropic bits lay in the lowest bits of the resulting
+  array index.  This gives significantly better locality of reference
+  and hence a small speedup despite the extra work involved in calculating
+  the index.
+
+  Why not six dimensions?  The expansion of dimensionality is good for random
+  access such as histogram population and the query pattern typical of
+  dithering but we have some code which iterates in a scanning manner, for
+  which the expansion is suboptimal.  The compromise is to leave the B
+  dimension unmolested in the lower-order bits of the index, since this is
+  the dimension most commonly iterated through in the inner loop of the
+  scans.
+
+  --adam
+
+  RhGhRlGlB
+*/
+#define VOL_GBITS  (PRECISION_G)
+#define VOL_BBITS  (PRECISION_B)
+#define VOL_RBITS  (PRECISION_R)
+#define VOL_GBITSh (VOL_GBITS - 3)
+#define VOL_GBITSl (VOL_GBITS - VOL_GBITSh)
+#define VOL_BBITSh (VOL_BBITS - 4)
+#define VOL_BBITSl (VOL_BBITS - VOL_BBITSh)
+#define VOL_RBITSh (VOL_RBITS - 3)
+#define VOL_RBITSl (VOL_RBITS - VOL_RBITSh)
+#define VOL_GMASKh (((1<<VOL_GBITSh)-1) << VOL_GBITSl)
+#define VOL_GMASKl ((1<<VOL_GBITSl)-1)
+#define VOL_BMASKh (((1<<VOL_BBITSh)-1) << VOL_BBITSl)
+#define VOL_BMASKl ((1<<VOL_BBITSl)-1)
+#define VOL_RMASKh (((1<<VOL_RBITSh)-1) << VOL_RBITSl)
+#define VOL_RMASKl ((1<<VOL_RBITSl)-1)
+/* The 5d compromise thing. */
+#define REF_FUNC(r,g,b) \
+( \
+ (((r) & VOL_RMASKh) << (VOL_BBITS + VOL_GBITS)) | \
+ (((r) & VOL_RMASKl) << (VOL_GBITSl + VOL_BBITS)) | \
+ (((g) & VOL_GMASKh) << (VOL_RBITSl + VOL_BBITS)) | \
+ (((g) & VOL_GMASKl) << (VOL_BBITS)) | \
+ (b) \
+)
+/* The full-on 6d thing. */
+/*
+#define REF_FUNC(r,g,b) \
+( \
+ (((r) & VOL_RMASKh) << (VOL_BBITS + VOL_GBITS)) | \
+ (((r) & VOL_RMASKl) << (VOL_GBITSl + VOL_BBITSl)) | \
+ (((g) & VOL_GMASKh) << (VOL_RBITSl + VOL_BBITS)) | \
+ (((g) & VOL_GMASKl) << (VOL_BBITSl)) | \
+ (((b) & VOL_BMASKh) << (VOL_RBITSl + VOL_GBITSl)) | \
+ ((b) & VOL_BMASKl) \
+)
+*/
+/* The boring old 3d thing. */
+/*
+#define REF_FUNC(r,g,b) (((r)<<(PRECISION_G+PRECISION_B)) | ((g)<<(PRECISION_B)) | (b))
+*/
+
+/* You even get to choose whether you want the accessor function
+   implemented as a macro or an inline function.  Don't say I never
+   give you anything. */
+/*
+#define HIST_LIN(hist_ptr,r,g,b) (&(hist_ptr)[REF_FUNC((r),(g),(b))])
+*/
+static inline ColorFreq *
+HIST_LIN (ColorFreq  *hist_ptr,
+          const gint  r,
+          const gint  g,
+          const gint  b)
+{
+  return (&(hist_ptr) [REF_FUNC (r, g, b)]);
+}
+
+
+#define LOWA   (-86.181F)
+#define LOWB  (-107.858F)
+#define HIGHA   (98.237F)
+#define HIGHB   (94.480F)
+
+#if 1
+#define LRAT (2.55F)
+#define ARAT (255.0F / (HIGHA - LOWA))
+#define BRAT (255.0F / (HIGHB - LOWB))
+#else
+#define LRAT (1.0F)
+#define ARAT (1.0F)
+#define BRAT (1.0F)
+#endif
+
+static const Babl *rgb_to_lab_fish = NULL;
+static const Babl *lab_to_rgb_fish = NULL;
+
+static inline void
+rgb_to_unshifted_lin (const guchar  r,
+                      const guchar  g,
+                      const guchar  b,
+                      gint         *hr,
+                      gint         *hg,
+                      gint         *hb)
+{
+  gint   or, og, ob;
+  gfloat rgb[3] = { r / 255.0, g / 255.0, b / 255.0 };
+  gfloat lab[3];
+
+  babl_process (rgb_to_lab_fish, rgb, lab, 1);
+
+  /* fprintf(stderr, " %d-%d-%d -> %0.3f,%0.3f,%0.3f ", r, g, b, sL, sa, sb);*/
+
+  or = RINT(lab[0] * LRAT);
+  og = RINT((lab[1] - LOWA) * ARAT);
+  ob = RINT((lab[2] - LOWB) * BRAT);
+
+  *hr = CLAMP(or, 0, 255);
+  *hg = CLAMP(og, 0, 255);
+  *hb = CLAMP(ob, 0, 255);
+
+  /*  fprintf(stderr, " %d:%d:%d ", *hr, *hg, *hb); */
+}
+
+
+static inline void
+rgb_to_lin (const guchar  r,
+            const guchar  g,
+            const guchar  b,
+            gint         *hr,
+            gint         *hg,
+            gint         *hb)
+{
+  gint or, og, ob;
+
+  /*
+  double sL, sa, sb;
+  {
+    double low_l = 999.0, low_a = 999.9, low_b = 999.0;
+    double high_l = -999.0, high_a = -999.0, high_b = -999.0;
+
+    int r,g,b;
+
+    for (r=0; r<256; r++)
+      for (g=0; g<256; g++)
+        for (b=0; b<256; b++)
+          {
+            cpercep_rgb_to_space(r,g,b, &sL, &sa, &sb);
+
+            if (sL > high_l)
+              high_l = sL;
+            if (sL < low_l)
+              low_l = sL;
+            if (sa > high_a)
+              high_a = sa;
+            if (sa < low_a)
+              low_a = sa;
+            if (sb > high_b)
+              high_b = sb;
+            if (sb < low_b)
+              low_b = sb;
+          }
+
+    fprintf(stderr, " [L: %0.3f -> %0.3f / a: %0.3f -> %0.3f / b: %0.3f -> %0.3f]\t", low_l, high_l, low_a, high_a, low_b, high_b);
+
+    exit(-1);
+  }
+  */
+
+  rgb_to_unshifted_lin (r, g, b, &or, &og, &ob);
+
+#if 0
+#define RSDF(r) ((r) >= ((HIST_R_ELEMS-1) << R_SHIFT) ? HIST_R_ELEMS-1 : \
+                 ((r) + ((1<<R_SHIFT)>>1) ) >> R_SHIFT)
+#define GSDF(g) ((g) >= ((HIST_G_ELEMS-1) << G_SHIFT) ? HIST_G_ELEMS-1 : \
+                 ((g) + ((1<<G_SHIFT)>>1) ) >> G_SHIFT)
+#define BSDF(b) ((b) >= ((HIST_B_ELEMS-1) << B_SHIFT) ? HIST_B_ELEMS-1 : \
+                 ((b) + ((1<<B_SHIFT)>>1) ) >> B_SHIFT)
+#else
+#define RSDF(r) ((r) >> R_SHIFT)
+#define GSDF(g) ((g) >> G_SHIFT)
+#define BSDF(b) ((b) >> B_SHIFT)
+#endif
+
+  or = RSDF (or);
+  og = GSDF (og);
+  ob = BSDF (ob);
+
+  *hr = or;
+  *hg = og;
+  *hb = ob;
+}
+
+
+static inline ColorFreq *
+HIST_RGB (ColorFreq  *hist_ptr,
+          const gint  r,
+          const gint  g,
+          const gint  b)
+{
+  gint hr, hg, hb;
+
+  rgb_to_lin (r, g, b, &hr, &hg, &hb);
+
+  return HIST_LIN (hist_ptr, hr, hg, hb);
+}
+
+
+static inline void
+lin_to_rgb (const gdouble  hr,
+            const gdouble  hg,
+            const gdouble  hb,
+            guchar        *r,
+            guchar        *g,
+            guchar        *b)
+{
+  gfloat  rgb[3];
+  gfloat  lab[3];
+  gdouble ir, ig, ib;
+
+  ir = ((gdouble) (hr)) * 255.0F / (gdouble) (HIST_R_ELEMS - 1);
+  ig = ((gdouble)( hg)) * 255.0F / (gdouble) (HIST_G_ELEMS - 1);
+  ib = ((gdouble)( hb)) * 255.0F / (gdouble) (HIST_B_ELEMS - 1);
+
+  ir = ir / LRAT;
+  ig = (ig / ARAT) + LOWA;
+  ib = (ib / BRAT) + LOWB;
+
+  lab[0] = ir;
+  lab[1] = ig;
+  lab[2] = ib;
+
+  babl_process (lab_to_rgb_fish, lab, rgb, 1);
+
+  *r = RINT (CLAMP (rgb[0] * 255, 0.0F, 255.0F));
+  *g = RINT (CLAMP (rgb[1] * 255, 0.0F, 255.0F));
+  *b = RINT (CLAMP (rgb[2] * 255, 0.0F, 255.0F));
+}
+
+
+
+struct _Color
+{
+  gint red;
+  gint green;
+  gint blue;
+};
+
+struct _QuantizeObj
+{
+  Pass1Func     first_pass;       /* first pass over image data creates colormap  */
+  Pass2InitFunc second_pass_init; /* Initialize data which persists over invocations */
+  Pass2Func     second_pass;      /* second pass maps from image data to colormap */
+  CleanupFunc   delete_func;      /* function to clean up data associated with private */
+
+  GimpPalette  *custom_palette;           /* The custom palette, if any        */
+
+  gint          desired_number_of_colors; /* Number of colors we will allow    */
+  gint          actual_number_of_colors;  /* Number of colors actually needed  */
+  Color         cmap[256];                /* colormap created by quantization  */
+  Color         clin[256];                /* .. converted back to linear space */
+  guint64       index_used_count[256];    /* how many times an index was used  */
+  CFHistogram   histogram;                /* holds the histogram               */
+
+  gboolean      want_dither_alpha;
+  gint          error_freedom;            /* 0=much bleed, 1=controlled bleed */
+
+  GimpProgress *progress;
+};
+
+typedef struct
+{
+  /*  The bounds of the box (inclusive); expressed as histogram indexes  */
+  gint    Rmin, Rmax;
+  gint    Rhalferror;
+  gint    Gmin, Gmax;
+  gint    Ghalferror;
+  gint    Bmin, Bmax;
+  gint    Bhalferror;
+
+  /*  The volume (actually 2-norm) of the box  */
+  gint    volume;
+
+  /*  The number of nonzero histogram cells within this box  */
+  gint64  colorcount;
+
+  /* The sum of the weighted error within this box */
+  guint64 error;
+  /* The sum of the unweighted error within this box */
+  guint64 rerror;
+  guint64 gerror;
+  guint64 berror;
+
+} box, *boxptr;
+
+
+static void          zero_histogram_gray     (CFHistogram   histogram);
+static void          zero_histogram_rgb      (CFHistogram   histogram);
+static void          generate_histogram_gray (CFHistogram   hostogram,
+                                              GimpLayer    *layer,
+                                              gboolean      dither_alpha);
+static void          generate_histogram_rgb  (CFHistogram   histogram,
+                                              GimpLayer    *layer,
+                                              gint          col_limit,
+                                              gboolean      dither_alpha,
+                                              GimpProgress *progress);
+
+static QuantizeObj * initialize_median_cut   (GimpImageBaseType      old_type,
+                                              gint                   max_colors,
+                                              GimpConvertDitherType  dither_type,
+                                              GimpConvertPaletteType palette_type,
+                                              GimpPalette           *custom_palette,
+                                              gboolean               dither_alpha,
+                                              GimpProgress          *progress);
+
+static void          compute_color_lin8      (QuantizeObj           *quantobj,
+                                              CFHistogram            histogram,
+                                              boxptr                 boxp,
+                                              const int              icolor);
+
+
+static guchar    found_cols[MAXNUMCOLORS][3];
+static gint      num_found_cols;
+static gboolean  needs_quantize;
+static gboolean  had_white;
+static gboolean  had_black;
+
+
+/**********************************************************/
+typedef struct
+{
+  gint64 used_count;
+  guchar initial_index;
+} PalEntry;
+
+static int
+mapping_compare (const void *a,
+                 const void *b)
+{
+  PalEntry *m1 = (PalEntry *) a;
+  PalEntry *m2 = (PalEntry *) b;
+
+  return (m2->used_count - m1->used_count);
+}
+
+/* FWIW, the make_remap_table() and mapping_compare() function source
+ * and PalEntry may be re-used under the XFree86-style license.
+ * <adam@gimp.org>
+ */
+static void
+make_remap_table (const guchar  old_palette[],
+                  guchar        new_palette[],
+                  const guint64 index_used_count[],
+                  guchar        remap_table[],
+                  gint         *num_entries)
+{
+  gint      i, j, k;
+  guchar    temppal[256 * 3];
+  guint64   tempuse[256];
+  guint64   transmap[256];
+  PalEntry *palentries;
+  gint      used = 0;
+
+  memset (temppal, 0, 256 * 3);
+  memset (tempuse, 0, 256 * sizeof (guint64));
+  memset (transmap, 255, 256 * sizeof (guint64));
+
+  /* First pass - only collect entries which are marked as being used
+   * at all in index_used_count.
+   */
+  for (i = 0; i < *num_entries; i++)
+    {
+      if (index_used_count[i])
+        {
+          temppal[used*3 + 0] = old_palette[i*3 + 0];
+          temppal[used*3 + 1] = old_palette[i*3 + 1];
+          temppal[used*3 + 2] = old_palette[i*3 + 2];
+
+          tempuse[used] = index_used_count[i];
+          transmap[i] = used;
+
+          used++;
+        }
+    }
+
+  /* Second pass - remove duplicates. (O(n^3), could do better!) */
+  for (i = 0; i < used; i++)
+    {
+      for (j = 0; j < i; j++)
+        {
+          if ((temppal[i*3 + 1] == temppal[j*3 + 1]) &&
+              (temppal[i*3 + 0] == temppal[j*3 + 0]) &&
+              (temppal[i*3 + 2] == temppal[j*3 + 2]) &&
+              tempuse[j] &&
+              tempuse[i])
+            {
+              /* Move the 'used' tally from one to the other. */
+              tempuse[i] += tempuse[j];
+              /* zero one of them, deactivating its entry. */
+              tempuse[j] = 0;
+
+              /* change all mappings from this dead index to the live
+               * one.
+               */
+              for (k = 0; k < *num_entries; k++)
+                {
+                  if (index_used_count[k] && (transmap[k] == j))
+                    transmap[k] = i;
+                }
+            }
+        }
+    }
+
+  /* Third pass - rank all used indices to the beginning of the
+   * palette.
+   */
+  palentries = g_new (PalEntry, used);
+
+  for (i = 0; i < used; i++)
+    {
+      palentries[i].initial_index = i;
+      palentries[i].used_count    = tempuse[i];
+    }
+
+  qsort (palentries, used, sizeof (PalEntry), &mapping_compare);
+
+  for (i = 0; i < *num_entries; i++)
+    {
+      if (index_used_count[i])
+        {
+          for (j = 0; j < used; j++)
+            {
+              if ((transmap[i] == palentries[j].initial_index)
+                  && (palentries[j].used_count))
+                {
+                  remap_table[i] = j;
+                  break;
+                }
+            }
+        }
+    }
+  for (i = 0; i < *num_entries; i++)
+    {
+      if (index_used_count[i])
+        {
+          new_palette[remap_table[i] * 3 + 0] = old_palette[i * 3 + 0];
+          new_palette[remap_table[i] * 3 + 1] = old_palette[i * 3 + 1];
+          new_palette[remap_table[i] * 3 + 2] = old_palette[i * 3 + 2];
+        }
+    }
+
+  *num_entries = 0;
+
+  for (j = 0; j < used; j++)
+    {
+      if (palentries[j].used_count)
+        {
+          (*num_entries)++;
+        }
+    }
+
+  g_free (palentries);
+}
+
+static void
+remap_indexed_layer (GimpLayer    *layer,
+                     const guchar *remap_table,
+                     gint          num_entries)
+{
+  GeglBufferIterator *iter;
+  const Babl         *format;
+  gint                bpp;
+  gboolean            has_alpha;
+
+  format  = gimp_drawable_get_format (GIMP_DRAWABLE (layer));
+
+  bpp       = babl_format_get_bytes_per_pixel (format);
+  has_alpha = babl_format_has_alpha (format);
+
+  iter = gegl_buffer_iterator_new (gimp_drawable_get_buffer (GIMP_DRAWABLE (layer)),
+                                   NULL, 0, NULL,
+                                   GEGL_ACCESS_READWRITE, GEGL_ABYSS_NONE, 1);
+
+  while (gegl_buffer_iterator_next (iter))
+    {
+      guchar *data   = iter->items[0].data;
+      gint    length = iter->length;
+
+      if (has_alpha)
+        {
+          while (length--)
+            {
+              if (data[ALPHA_I])
+                data[INDEXED] = remap_table[data[INDEXED]];
+              else
+                data[INDEXED] = 0;
+
+              data += bpp;
+            }
+        }
+      else
+        {
+          while (length--)
+            {
+              data[INDEXED] = remap_table[data[INDEXED]];
+
+              data += bpp;
+            }
+        }
+    }
+}
+
+static gint
+color_quicksort (const void *c1,
+                 const void *c2)
+{
+  Color *color1 = (Color *) c1;
+  Color *color2 = (Color *) c2;
+
+  gdouble v1 = GIMP_RGB_LUMINANCE (color1->red, color1->green, color1->blue);
+  gdouble v2 = GIMP_RGB_LUMINANCE (color2->red, color2->green, color2->blue);
+
+  if (v1 < v2)
+    return -1;
+  else if (v1 > v2)
+    return 1;
+  else
+    return 0;
+}
+
+gboolean
+gimp_image_convert_indexed (GimpImage               *image,
+                            GimpConvertPaletteType   palette_type,
+                            gint                     max_colors,
+                            gboolean                 remove_duplicates,
+                            GimpConvertDitherType    dither_type,
+                            gboolean                 dither_alpha,
+                            gboolean                 dither_text_layers,
+                            GimpPalette             *custom_palette,
+                            GimpProgress            *progress,
+                            GError                 **error)
+{
+  QuantizeObj       *quantobj     = NULL;
+  GimpObjectQueue   *queue        = NULL;
+  GimpProgress      *sub_progress = NULL;
+  GimpImageBaseType  old_type;
+  GList             *all_layers;
+  GList             *list;
+  GimpColorProfile  *dest_profile = NULL;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+  g_return_val_if_fail (gimp_image_get_base_type (image) != GIMP_INDEXED, FALSE);
+  g_return_val_if_fail (gimp_babl_is_valid (GIMP_INDEXED,
+                                            gimp_image_get_precision (image)),
+                        FALSE);
+  g_return_val_if_fail (custom_palette == NULL ||
+                        GIMP_IS_PALETTE (custom_palette), FALSE);
+  g_return_val_if_fail (custom_palette == NULL ||
+                        gimp_palette_get_n_colors (custom_palette) <= 256,
+                        FALSE);
+  g_return_val_if_fail (progress == NULL || GIMP_IS_PROGRESS (progress), FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  if (palette_type == GIMP_CONVERT_PALETTE_CUSTOM)
+    {
+      if (! custom_palette)
+        palette_type = GIMP_CONVERT_PALETTE_MONO;
+
+      if (gimp_palette_get_n_colors (custom_palette) == 0)
+        {
+          g_set_error_literal (error, GIMP_ERROR, GIMP_FAILED,
+                               _("Cannot convert image: palette is empty."));
+          return FALSE;
+        }
+    }
+
+  gimp_set_busy (image->gimp);
+
+  all_layers = gimp_image_get_layer_list (image);
+
+  g_object_freeze_notify (G_OBJECT (image));
+
+  gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_IMAGE_CONVERT,
+                               C_("undo-type", "Convert Image to Indexed"));
+
+  /*  Push the image type to the stack  */
+  gimp_image_undo_push_image_type (image, NULL);
+
+  /*  Set the new base type  */
+  old_type = gimp_image_get_base_type (image);
+
+  g_object_set (image, "base-type", GIMP_INDEXED, NULL);
+
+  /* when converting from GRAY, convert to the new type's builtin
+   * profile.
+   */
+  if (old_type == GIMP_GRAY)
+    {
+      if (gimp_image_get_color_profile (image))
+        dest_profile = gimp_image_get_builtin_color_profile (image);
+    }
+
+  /*  Build histogram if necessary.  */
+  rgb_to_lab_fish = babl_fish (babl_format ("R'G'B' float"),
+                               babl_format ("CIE Lab float"));
+  lab_to_rgb_fish = babl_fish (babl_format ("CIE Lab float"),
+                               babl_format ("R'G'B' float"));
+
+  /* don't dither if the input is grayscale and we are simply mapping
+   * every color
+   */
+  if (old_type     == GIMP_GRAY &&
+      max_colors   == 256       &&
+      palette_type == GIMP_CONVERT_PALETTE_GENERATE)
+    {
+      dither_type = GIMP_CONVERT_DITHER_NONE;
+    }
+
+  if (progress)
+    {
+      queue        = gimp_object_queue_new (progress);
+      sub_progress = GIMP_PROGRESS (queue);
+
+      gimp_object_queue_push_list (queue, all_layers);
+    }
+
+  quantobj = initialize_median_cut (old_type, max_colors, dither_type,
+                                    palette_type, custom_palette,
+                                    dither_alpha,
+                                    sub_progress);
+
+  if (palette_type == GIMP_CONVERT_PALETTE_GENERATE)
+    {
+      if (old_type == GIMP_GRAY)
+        zero_histogram_gray (quantobj->histogram);
+      else
+        zero_histogram_rgb (quantobj->histogram);
+
+      /* To begin, assume that there are fewer colors in the image
+       *  than the user actually asked for.  In that case, we don't
+       *  need to quantize or color-dither.
+       */
+      needs_quantize = FALSE;
+      had_black = FALSE;
+      had_white = FALSE;
+      num_found_cols = 0;
+
+      /*  Build the histogram  */
+      for (list = all_layers;
+           list;
+           list = g_list_next (list))
+        {
+          GimpLayer *layer = list->data;
+
+          if (queue)
+            gimp_object_queue_pop (queue);
+
+          if (old_type == GIMP_GRAY)
+            {
+              generate_histogram_gray (quantobj->histogram,
+                                       layer, dither_alpha);
+            }
+          else
+            {
+              /* Note: generate_histogram_rgb may set needs_quantize
+               * if the image contains more colors than the limit
+               * specified by the user.
+               */
+              generate_histogram_rgb (quantobj->histogram,
+                                      layer, max_colors, dither_alpha,
+                                      sub_progress);
+            }
+        }
+    }
+
+  if (progress)
+    gimp_progress_set_text_literal (progress,
+                                    _("Converting to indexed colors (stage 2)"));
+
+  if (old_type == GIMP_RGB &&
+      ! needs_quantize     &&
+      palette_type == GIMP_CONVERT_PALETTE_GENERATE)
+    {
+      gint i;
+
+      /*  If this is an RGB image, and the user wanted a custom-built
+       *  generated palette, and this image has no more colors than
+       *  the user asked for, we don't need the first pass
+       *  (quantization).
+       *
+       *  There's also no point in dithering, since there's no error
+       *  to spread.  So we destroy the old quantobj and make a new
+       *  one with the remapping function set to a special LUT-based
+       *  no-dither remapper.
+       */
+
+      quantobj->delete_func (quantobj);
+      quantobj = initialize_median_cut (old_type, max_colors,
+                                        GIMP_CONVERT_DITHER_NODESTRUCT,
+                                        palette_type,
+                                        custom_palette,
+                                        dither_alpha,
+                                        sub_progress);
+      /* We can skip the first pass (palette creation) */
+
+      quantobj->actual_number_of_colors = num_found_cols;
+      for (i = 0; i < num_found_cols; i++)
+        {
+          quantobj->cmap[i].red   = found_cols[i][0];
+          quantobj->cmap[i].green = found_cols[i][1];
+          quantobj->cmap[i].blue  = found_cols[i][2];
+        }
+    }
+  else
+    {
+      quantobj->first_pass (quantobj);
+    }
+
+  if (palette_type == GIMP_CONVERT_PALETTE_GENERATE)
+    qsort (quantobj->cmap,
+           quantobj->actual_number_of_colors, sizeof (Color),
+           color_quicksort);
+
+  if (progress)
+    {
+      gimp_progress_set_text_literal (progress,
+                                      _("Converting to indexed colors (stage 3)"));
+
+      gimp_object_queue_clear (queue);
+      gimp_object_queue_push_list (queue, all_layers);
+    }
+
+  /* Initialise data which must persist across indexed layer iterations */
+  if (quantobj->second_pass_init)
+    quantobj->second_pass_init (quantobj);
+
+  /*  Set the generated palette on the image, we need it to
+   *  convert the layers. We optionally remove duplicate entries
+   *  after the layer conversion.
+   */
+  {
+    guchar colormap[GIMP_IMAGE_COLORMAP_SIZE];
+    gint   i, j;
+
+    for (i = 0, j = 0; i < quantobj->actual_number_of_colors; i++)
+      {
+        colormap[j++] = quantobj->cmap[i].red;
+        colormap[j++] = quantobj->cmap[i].green;
+        colormap[j++] = quantobj->cmap[i].blue;
+      }
+
+    gimp_image_set_colormap (image, colormap,
+                             quantobj->actual_number_of_colors, TRUE);
+  }
+
+  /*  Convert all layers  */
+  for (list = all_layers;
+       list;
+       list = g_list_next (list))
+    {
+      GimpLayer *layer = list->data;
+      gboolean   quantize;
+
+      if (queue)
+        gimp_object_queue_pop (queue);
+
+      if (gimp_item_is_text_layer (GIMP_ITEM (layer)))
+        quantize = dither_text_layers;
+      else
+        quantize = TRUE;
+
+      if (quantize)
+        {
+          GeglBuffer *new_buffer;
+          gboolean    has_alpha;
+
+          has_alpha = gimp_drawable_has_alpha (GIMP_DRAWABLE (layer));
+
+          new_buffer =
+            gegl_buffer_new (GEGL_RECTANGLE (0, 0,
+                                             gimp_item_get_width  (GIMP_ITEM (layer)),
+                                             gimp_item_get_height (GIMP_ITEM (layer))),
+                             gimp_image_get_layer_format (image,
+                                                          has_alpha));
+
+          quantobj->second_pass (quantobj, layer, new_buffer);
+
+          gimp_drawable_set_buffer (GIMP_DRAWABLE (layer), TRUE, NULL,
+                                    new_buffer);
+          g_object_unref (new_buffer);
+        }
+      else
+        {
+          gimp_drawable_convert_type (GIMP_DRAWABLE (layer), image,
+                                      GIMP_INDEXED,
+                                      gimp_drawable_get_precision (GIMP_DRAWABLE (layer)),
+                                      gimp_drawable_has_alpha (GIMP_DRAWABLE (layer)),
+                                      dest_profile,
+                                      GEGL_DITHER_NONE, GEGL_DITHER_NONE,
+                                      TRUE, sub_progress);
+        }
+    }
+
+  /*  Set the final palette on the image  */
+  if (remove_duplicates &&
+      (palette_type != GIMP_CONVERT_PALETTE_GENERATE) &&
+      (palette_type != GIMP_CONVERT_PALETTE_MONO))
+    {
+      guchar colormap[GIMP_IMAGE_COLORMAP_SIZE];
+      gint   i, j;
+      guchar old_palette[256 * 3];
+      guchar new_palette[256 * 3];
+      guchar remap_table[256];
+      gint   num_entries;
+
+      for (i = 0, j = 0; i < quantobj->actual_number_of_colors; i++)
+        {
+          old_palette[j++] = quantobj->cmap[i].red;
+          old_palette[j++] = quantobj->cmap[i].green;
+          old_palette[j++] = quantobj->cmap[i].blue;
+        }
+
+      num_entries = quantobj->actual_number_of_colors;
+
+      /* Generate a remapping table */
+      make_remap_table (old_palette, new_palette,
+                        quantobj->index_used_count,
+                        remap_table, &num_entries);
+
+      /*  Convert all layers  */
+      for (list = all_layers; list; list = g_list_next (list))
+        {
+          remap_indexed_layer (list->data, remap_table, num_entries);
+        }
+
+      for (i = 0, j = 0; i < num_entries; i++)
+        {
+          colormap[j] = new_palette[j]; j++;
+          colormap[j] = new_palette[j]; j++;
+          colormap[j] = new_palette[j]; j++;
+        }
+
+      gimp_image_set_colormap (image, colormap, num_entries, TRUE);
+    }
+
+  /*  When converting from GRAY, set the new profile.
+   */
+  if (old_type == GIMP_GRAY)
+    {
+      if (gimp_image_get_color_profile (image))
+        gimp_image_set_color_profile (image, dest_profile, NULL);
+      else
+        gimp_color_managed_profile_changed (GIMP_COLOR_MANAGED (image));
+    }
+
+  /*  Delete the quantizer object, if there is one */
+  if (quantobj)
+    quantobj->delete_func (quantobj);
+
+  gimp_image_undo_group_end (image);
+
+  gimp_image_mode_changed (image);
+  g_object_thaw_notify (G_OBJECT (image));
+
+  g_clear_object (&queue);
+
+  g_list_free (all_layers);
+
+  gimp_unset_busy (image->gimp);
+
+  return TRUE;
+}
+
+/*
+ *  Indexed color conversion machinery
+ */
+
+static void
+zero_histogram_gray (CFHistogram histogram)
+{
+  gint i;
+
+  for (i = 0; i < 256; i++)
+    histogram[i] = 0;
+}
+
+
+static void
+zero_histogram_rgb (CFHistogram histogram)
+{
+  memset (histogram, 0,
+          HIST_R_ELEMS * HIST_G_ELEMS * HIST_B_ELEMS * sizeof (ColorFreq));
+}
+
+
+static void
+generate_histogram_gray (CFHistogram  histogram,
+                         GimpLayer   *layer,
+                         gboolean     dither_alpha)
+{
+  GeglBufferIterator *iter;
+  const Babl         *format;
+  gint                bpp;
+  gboolean            has_alpha;
+
+  format = gimp_drawable_get_format (GIMP_DRAWABLE (layer));
+
+  g_return_if_fail (format == babl_format_with_space ("Y' u8", format) ||
+                    format == babl_format_with_space ("Y'A u8", format));
+
+  bpp       = babl_format_get_bytes_per_pixel (format);
+  has_alpha = babl_format_has_alpha (format);
+
+  iter = gegl_buffer_iterator_new (gimp_drawable_get_buffer (GIMP_DRAWABLE (layer)),
+                                   NULL, 0, format,
+                                   GEGL_ACCESS_READ, GEGL_ABYSS_NONE, 1);
+
+  while (gegl_buffer_iterator_next (iter))
+    {
+      const guchar *data   = iter->items[0].data;
+      gint          length = iter->length;
+
+      if (has_alpha)
+        {
+          while (length--)
+            {
+              if (data[ALPHA_G] > 127)
+                histogram[*data]++;
+
+              data += bpp;
+            }
+        }
+      else
+        {
+          while (length--)
+            {
+              histogram[*data]++;
+
+              data += bpp;
+            }
+        }
+    }
+}
+
+static void
+check_white_or_black (const guchar *data)
+{
+  if (data[RED]   == 255 &&
+      data[GREEN] == 255 &&
+      data[BLUE]  == 255)
+    had_white = TRUE;
+  if (data[RED]  ==0 &&
+      data[GREEN]==0 &&
+      data[BLUE] ==0)
+    had_black = TRUE;
+}
+
+static void
+generate_histogram_rgb (CFHistogram   histogram,
+                        GimpLayer    *layer,
+                        gint          col_limit,
+                        gboolean      dither_alpha,
+                        GimpProgress *progress)
+{
+  GeglBufferIterator *iter;
+  const Babl         *format;
+  GeglRectangle      *roi;
+  ColorFreq          *colfreq;
+  gint                nfc_iter;
+  gint                row, col, coledge;
+  gint                offsetx, offsety;
+  gint64              layer_size;
+  gint64              total_size = 0;
+  gint                count      = 0;
+  gint                bpp;
+  gboolean            has_alpha;
+
+  format = gimp_drawable_get_format (GIMP_DRAWABLE (layer));
+
+  g_return_if_fail (format == babl_format ("R'G'B' u8") ||
+                    format == babl_format ("R'G'B'A u8"));
+
+  bpp       = babl_format_get_bytes_per_pixel (format);
+  has_alpha = babl_format_has_alpha (format);
+
+  gimp_item_get_offset (GIMP_ITEM (layer), &offsetx, &offsety);
+
+  layer_size = (gimp_item_get_width  (GIMP_ITEM (layer)) *
+                gimp_item_get_height (GIMP_ITEM (layer)));
+
+  /*  g_printerr ("col_limit = %d, nfc = %d\n", col_limit, num_found_cols); */
+
+  iter = gegl_buffer_iterator_new (gimp_drawable_get_buffer (GIMP_DRAWABLE (layer)),
+                                   NULL, 0, format,
+                                   GEGL_ACCESS_READ, GEGL_ABYSS_NONE, 1);
+  roi = &iter->items[0].roi;
+
+  if (progress)
+    gimp_progress_set_value (progress, 0.0);
+
+  while (gegl_buffer_iterator_next (iter))
+    {
+      const guchar *data   = iter->items[0].data;
+      gint          length = iter->length;
+
+      total_size += length;
+
+      /* g_printerr (" [%d,%d - %d,%d]", srcPR.x, src_roi->y, offsetx, offsety); */
+
+      if (needs_quantize)
+        {
+          if (dither_alpha)
+            {
+              /* if alpha-dithering,
+                 we need to be deterministic w.r.t. offsets */
+
+              col = roi->x + offsetx;
+              coledge = col + roi->width;
+              row = roi->y + offsety;
+
+              while (length--)
+                {
+                  gboolean transparent = FALSE;
+
+                  if (has_alpha &&
+                      data[ALPHA] <
+                      DM[col & DM_WIDTHMASK][row & DM_HEIGHTMASK])
+                    transparent = TRUE;
+
+                  if (! transparent)
+                    {
+                      colfreq = HIST_RGB (histogram,
+                                          data[RED],
+                                          data[GREEN],
+                                          data[BLUE]);
+                      check_white_or_black (data);
+                      (*colfreq)++;
+                    }
+
+                  col++;
+                  if (col == coledge)
+                    {
+                      col = roi->x + offsetx;
+                      row++;
+                    }
+
+                  data += bpp;
+                }
+            }
+          else
+            {
+              while (length--)
+                {
+                  if ((has_alpha && ((data[ALPHA] > 127)))
+                      || (!has_alpha))
+                    {
+                      colfreq = HIST_RGB (histogram,
+                                          data[RED],
+                                          data[GREEN],
+                                          data[BLUE]);
+                      check_white_or_black (data);
+                      (*colfreq)++;
+                    }
+
+                  data += bpp;
+                }
+            }
+        }
+      else
+        {
+          /* if alpha-dithering, we need to be deterministic w.r.t. offsets */
+          col = roi->x + offsetx;
+          coledge = col + roi->width;
+          row = roi->y + offsety;
+
+          while (length--)
+            {
+              gboolean transparent = FALSE;
+
+              if (has_alpha)
+                {
+                  if (dither_alpha)
+                    {
+                      if (data[ALPHA] <
+                          DM[col & DM_WIDTHMASK][row & DM_HEIGHTMASK])
+                        transparent = TRUE;
+                    }
+                  else
+                    {
+                      if (data[ALPHA] <= 127)
+                        transparent = TRUE;
+                    }
+                }
+
+              if (! transparent)
+                {
+                  colfreq = HIST_RGB (histogram,
+                                      data[RED],
+                                      data[GREEN],
+                                      data[BLUE]);
+                  (*colfreq)++;
+
+                  if (!needs_quantize)
+                    {
+                      for (nfc_iter = 0;
+                           nfc_iter < num_found_cols;
+                           nfc_iter++)
+                        {
+                          if ((data[RED]   == found_cols[nfc_iter][0]) &&
+                              (data[GREEN] == found_cols[nfc_iter][1]) &&
+                              (data[BLUE]  == found_cols[nfc_iter][2]))
+                            goto already_found;
+                        }
+
+                      /* Color was not in the table of
+                       * existing colors
+                       */
+
+                      num_found_cols++;
+
+                      if (num_found_cols > col_limit)
+                        {
+                          /* There are more colors in the image than
+                           *  were allowed.  We switch to plain
+                           *  histogram calculation with a view to
+                           *  quantizing at a later stage.
+                           */
+                          needs_quantize = TRUE;
+                          /* g_print ("\nmax colors exceeded - needs quantize.\n");*/
+                          goto already_found;
+                        }
+                      else
+                        {
+                          /* Remember the new color we just found.
+                           */
+                          found_cols[num_found_cols-1][0] = data[RED];
+                          found_cols[num_found_cols-1][1] = data[GREEN];
+                          found_cols[num_found_cols-1][2] = data[BLUE];
+
+                          check_white_or_black (data);
+                        }
+                    }
+                }
+            already_found:
+
+              col++;
+              if (col == coledge)
+                {
+                  col = roi->x + offsetx;
+                  row++;
+                }
+
+              data += bpp;
+            }
+        }
+
+      if (progress && (count % 16 == 0))
+        gimp_progress_set_value (progress,
+                                 (gdouble) total_size / (gdouble) layer_size);
+    }
+
+/*  g_print ("O: col_limit = %d, nfc = %d\n", col_limit, num_found_cols);*/
+}
+
+
+
+static boxptr
+find_split_candidate (const boxptr  boxlist,
+                      const gint    numboxes,
+                      AxisType     *which_axis,
+                      const gint    desired_colors)
+{
+  boxptr  boxp;
+  gint    i;
+  etype   maxc = 0;
+  boxptr  which = NULL;
+  gdouble Lbias;
+
+  *which_axis = AXIS_UNDEF;
+
+  /* we only perform the initial L-split bias /at all/ if the final
+     number of desired colors is quite low, otherwise it all comes
+     out in the wash anyway and this initial bias generally only hurts
+     us in the long run. */
+  if (desired_colors <= 16)
+    {
+#define BIAS_FACTOR 2.66F
+#define BIAS_NUMBER 2 /* 0 */
+
+      /* we bias towards splitting across L* for first few colors */
+      Lbias = (numboxes > BIAS_NUMBER) ? 1.0F : ((gdouble) (BIAS_NUMBER + 1) -
+                                                 ((gdouble) numboxes)) /
+        ((gdouble) BIAS_NUMBER / BIAS_FACTOR);
+      /*Lbias = 1.0;
+        fprintf(stderr, " [[%d]] ", numboxes);
+        fprintf(stderr, "Using ramped L-split bias.\n");
+        fprintf(stderr, "R\n");
+      */
+    }
+  else
+    Lbias = 1.0F;
+
+  for (i = 0, boxp = boxlist; i < numboxes; i++, boxp++)
+    {
+      if (boxp->volume > 0)
+        {
+#ifndef _MSC_VER
+          etype rpe = (double)((boxp->rerror) * R_SCALE * R_SCALE);
+          etype gpe = (double)((boxp->gerror) * G_SCALE * G_SCALE);
+          etype bpe = (double)((boxp->berror) * B_SCALE * B_SCALE);
+#else
+          /*
+           * Sorry about the mess, otherwise would get :
+           * error C2520: conversion from unsigned __int64 to double
+           *              not implemented, use signed __int64
+           */
+          etype rpe = (double)(((__int64)boxp->rerror) * R_SCALE * R_SCALE);
+          etype gpe = (double)(((__int64)boxp->gerror) * G_SCALE * G_SCALE);
+          etype bpe = (double)(((__int64)boxp->berror) * B_SCALE * B_SCALE);
+#endif
+
+          if (Lbias * rpe > maxc &&
+              boxp->Rmin < boxp->Rmax)
+            {
+              which = boxp;
+              maxc  = Lbias * rpe;
+              *which_axis = AXIS_RED;
+            }
+
+          if (gpe > maxc &&
+              boxp->Gmin < boxp->Gmax)
+            {
+              which = boxp;
+              maxc  = gpe;
+              *which_axis = AXIS_GREEN;
+            }
+
+          if (bpe > maxc &&
+              boxp->Bmin < boxp->Bmax)
+            {
+              which = boxp;
+              maxc  = bpe;
+              *which_axis = AXIS_BLUE;
+            }
+        }
+    }
+
+  /*  fprintf(stderr, " %f,%p ", maxc, which); */
+  /*  fprintf(stderr, " %llu ", maxc); */
+
+  return which;
+}
+
+
+/* Find the splittable box with the largest (scaled) volume Returns
+ * NULL if no splittable boxes remain
+ */
+static boxptr
+find_biggest_volume (const boxptr boxlist,
+                     const gint   numboxes)
+{
+  boxptr boxp;
+  gint   i;
+  gint   maxv = 0;
+  boxptr which = NULL;
+
+  for (i = 0, boxp = boxlist; i < numboxes; i++, boxp++)
+    {
+      if (boxp->volume > maxv)
+        {
+          which = boxp;
+          maxv = boxp->volume;
+        }
+    }
+
+  return which;
+}
+
+
+/* Shrink the min/max bounds of a box to enclose only nonzero
+ * elements, and recompute its volume and population
+ */
+static void
+update_box_gray (const CFHistogram histogram,
+                 boxptr            boxp)
+{
+  gint      i, min, max, dist;
+  ColorFreq ccount;
+
+  min = boxp->Rmin;
+  max = boxp->Rmax;
+
+  if (max > min)
+    for (i = min; i <= max; i++)
+      {
+        if (histogram[i] != 0)
+          {
+            boxp->Rmin = min = i;
+            break;
+          }
+      }
+
+  if (max > min)
+    for (i = max; i >= min; i--)
+      {
+        if (histogram[i] != 0)
+          {
+            boxp->Rmax = max = i;
+            break;
+          }
+      }
+
+  /* Update box volume.
+   * We use 2-norm rather than real volume here; this biases the method
+   * against making long narrow boxes, and it has the side benefit that
+   * a box is splittable iff norm > 0.
+   * Since the differences are expressed in histogram-cell units,
+   * we have to shift back to JSAMPLE units to get consistent distances;
+   * after which, we scale according to the selected distance scale factors.
+   */
+  dist = max - min;
+  boxp->volume = dist * dist;
+
+  /* Now scan remaining volume of box and compute population */
+  ccount = 0;
+  for (i = min; i <= max; i++)
+    if (histogram[i] != 0)
+      ccount++;
+
+  boxp->colorcount = ccount;
+}
+
+
+/* Shrink the min/max bounds of a box to enclose only nonzero
+ * elements, and recompute its volume, population and error
+ */
+static void
+update_box_rgb (const CFHistogram histogram,
+                boxptr            boxp,
+                const gint        cells_remaining)
+{
+  gint      R, G, B;
+  gint      Rmin, Rmax, Gmin, Gmax, Bmin, Bmax;
+  gint      dist0, dist1, dist2;
+  ColorFreq ccount;
+  /*
+  guint64 tempRerror;
+  guint64 tempGerror;
+  guint64 tempBerror;
+  */
+  QuantizeObj dummyqo;
+  box         dummybox;
+
+  /* fprintf(stderr, "U"); */
+
+  Rmin = boxp->Rmin;  Rmax = boxp->Rmax;
+  Gmin = boxp->Gmin;  Gmax = boxp->Gmax;
+  Bmin = boxp->Bmin;  Bmax = boxp->Bmax;
+
+  if (Rmax > Rmin)
+    for (R = Rmin; R <= Rmax; R++)
+      for (G = Gmin; G <= Gmax; G++)
+        {
+          for (B = Bmin; B <= Bmax; B++)
+            {
+              if (*HIST_LIN (histogram, R, G, B) != 0)
+                {
+                  boxp->Rmin = Rmin = R;
+                  goto have_Rmin;
+                }
+            }
+        }
+ have_Rmin:
+  if (Rmax > Rmin)
+    for (R = Rmax; R >= Rmin; R--)
+      for (G = Gmin; G <= Gmax; G++)
+        {
+          for (B = Bmin; B <= Bmax; B++)
+            {
+              if (*HIST_LIN (histogram, R, G, B) != 0)
+                {
+                  boxp->Rmax = Rmax = R;
+                  goto have_Rmax;
+                }
+            }
+        }
+ have_Rmax:
+  if (Gmax > Gmin)
+    for (G = Gmin; G <= Gmax; G++)
+      for (R = Rmin; R <= Rmax; R++)
+        {
+          for (B = Bmin; B <= Bmax; B++)
+            {
+              if (*HIST_LIN (histogram, R, G, B) != 0)
+                {
+                  boxp->Gmin = Gmin = G;
+                  goto have_Gmin;
+                }
+            }
+        }
+ have_Gmin:
+  if (Gmax > Gmin)
+    for (G = Gmax; G >= Gmin; G--)
+      for (R = Rmin; R <= Rmax; R++)
+        {
+          for (B = Bmin; B <= Bmax; B++)
+            {
+              if (*HIST_LIN (histogram, R, G, B) != 0)
+                {
+                  boxp->Gmax = Gmax = G;
+                  goto have_Gmax;
+                }
+            }
+        }
+ have_Gmax:
+  if (Bmax > Bmin)
+    for (B = Bmin; B <= Bmax; B++)
+      for (R = Rmin; R <= Rmax; R++)
+        {
+          for (G = Gmin; G <= Gmax; G++)
+            {
+              if (*HIST_LIN (histogram, R, G, B) != 0)
+                {
+                  boxp->Bmin = Bmin = B;
+                  goto have_Bmin;
+                }
+            }
+        }
+ have_Bmin:
+  if (Bmax > Bmin)
+    for (B = Bmax; B >= Bmin; B--)
+      for (R = Rmin; R <= Rmax; R++)
+        {
+          for (G = Gmin; G <= Gmax; G++)
+            {
+              if (*HIST_LIN (histogram, R, G, B) != 0)
+                {
+                  boxp->Bmax = Bmax = B;
+                  goto have_Bmax;
+                }
+            }
+        }
+ have_Bmax:
+
+  /* Update box volume.
+   * We use 2-norm rather than real volume here; this biases the method
+   * against making long narrow boxes, and it has the side benefit that
+   * a box is splittable iff norm > 0. (ADM: note: this isn't true.)
+   * Since the differences are expressed in histogram-cell units,
+   * we have to shift back to JSAMPLE units to get consistent distances;
+   * after which, we scale according to the selected distance scale factors.
+   */
+  dist0 = ((1 + Rmax - Rmin) << R_SHIFT) * R_SCALE;
+  dist1 = ((1 + Gmax - Gmin) << G_SHIFT) * G_SCALE;
+  dist2 = ((1 + Bmax - Bmin) << B_SHIFT) * B_SCALE;
+  boxp->volume = dist0*dist0 + dist1*dist1 + dist2*dist2;
+  /*  boxp->volume = dist0 * dist1 * dist2; */
+
+  compute_color_lin8(&dummyqo, histogram, boxp, 0);
+
+  /*printf("(%d %d %d)\n", dummyqo.cmap[0].red,dummyqo.cmap[0].green,dummyqo.cmap[0].blue);
+    fflush(stdout);*/
+
+  /* Now scan remaining volume of box and compute population */
+  ccount = 0;
+  boxp->error = 0;
+  boxp->rerror = 0;
+  boxp->gerror = 0;
+  boxp->berror = 0;
+  for (R = Rmin; R <= Rmax; R++)
+    {
+      for (G = Gmin; G <= Gmax; G++)
+        {
+          for (B = Bmin; B <= Bmax; B++)
+            {
+              ColorFreq freq_here;
+
+              freq_here = *HIST_LIN (histogram, R, G, B);
+
+              if (freq_here != 0)
+                {
+                  int ge, be, re;
+
+                  dummybox.Rmin = dummybox.Rmax = R;
+                  dummybox.Gmin = dummybox.Gmax = G;
+                  dummybox.Bmin = dummybox.Bmax = B;
+                  compute_color_lin8(&dummyqo, histogram, &dummybox, 1);
+
+                  re = dummyqo.cmap[0].red   - dummyqo.cmap[1].red;
+                  ge = dummyqo.cmap[0].green - dummyqo.cmap[1].green;
+                  be = dummyqo.cmap[0].blue  - dummyqo.cmap[1].blue;
+
+                  boxp->rerror += freq_here * (re) * (re);
+                  boxp->gerror += freq_here * (ge) * (ge);
+                  boxp->berror += freq_here * (be) * (be);
+
+                  ccount += freq_here;
+                }
+            }
+        }
+    }
+
+#if 0
+  fg d;flg fd;kg fld;gflkfld
+  /* Scan again, taking note of halfway error point for red axis */
+  tempRerror = 0;
+  boxp->Rhalferror = Rmin;
+#warning r<=?
+  for (R = Rmin; R <= Rmax; R++)
+    {
+      for (G = Gmin; G <= Gmax; G++)
+        {
+          for (B = Bmin; B <= Bmax; B++)
+            {
+              ColorFreq freq_here;
+              freq_here = *HIST_LIN(histogram, R, G, B);
+              if (freq_here != 0)
+                {
+                  int re;
+                  int idist;
+                  double dist;
+
+                  dummybox.Rmin = dummybox.Rmax = R;
+                  dummybox.Gmin = dummybox.Gmax = G;
+                  dummybox.Bmin = dummybox.Bmax = B;
+                  compute_color_lin8(&dummyqo, histogram, &dummybox, 1);
+
+                  re = dummyqo.cmap[0].red   - dummyqo.cmap[1].red;
+
+                  tempRerror += freq_here * (re) * (re);
+
+                  if (tempRerror*2 >= boxp->rerror)
+                    goto green_axisscan;
+                  else
+                    boxp->Rhalferror = R;
+                }
+            }
+        }
+    }
+  fprintf(stderr, " D:");
+ green_axisscan:
+
+  fprintf(stderr, "<%d: %llu/%llu> ", R, tempRerror, boxp->rerror);
+  /* Scan again, taking note of halfway error point for green axis */
+  tempGerror = 0;
+  boxp->Ghalferror = Gmin;
+#warning G<=?
+  for (G = Gmin; G <= Gmax; G++)
+    {
+      for (R = Rmin; R <= Rmax; R++)
+        {
+          for (B = Bmin; B <= Bmax; B++)
+            {
+              ColorFreq freq_here;
+              freq_here = *HIST_LIN(histogram, R, G, B);
+              if (freq_here != 0)
+                {
+                  int ge;
+                  dummybox.Rmin = dummybox.Rmax = R;
+                  dummybox.Gmin = dummybox.Gmax = G;
+                  dummybox.Bmin = dummybox.Bmax = B;
+                  compute_color_lin8(&dummyqo, histogram, &dummybox, 1);
+
+                  ge = dummyqo.cmap[0].green - dummyqo.cmap[1].green;
+
+                  tempGerror += freq_here * (ge) * (ge);
+
+                  if (tempGerror*2 >= boxp->gerror)
+                    goto blue_axisscan;
+                  else
+                    boxp->Ghalferror = G;
+                }
+            }
+        }
+    }
+
+ blue_axisscan:
+  /* Scan again, taking note of halfway error point for blue axis */
+  tempBerror = 0;
+  boxp->Bhalferror = Bmin;
+#warning B<=?
+  for (B = Bmin; B <= Bmax; B++)
+    {
+      for (R = Rmin; R <= Rmax; R++)
+        {
+          for (G = Gmin; G <= Gmax; G++)
+            {
+              ColorFreq freq_here;
+              freq_here = *HIST_LIN(histogram, R, G, B);
+              if (freq_here != 0)
+                {
+                  int be;
+                  dummybox.Rmin = dummybox.Rmax = R;
+                  dummybox.Gmin = dummybox.Gmax = G;
+                  dummybox.Bmin = dummybox.Bmax = B;
+                  compute_color_lin8(&dummyqo, histogram, &dummybox, 1);
+
+                  be = dummyqo.cmap[0].blue  - dummyqo.cmap[1].blue;
+
+                  tempBerror += freq_here * (be) * (be);
+
+                  if (tempBerror*2 >= boxp->berror)
+                    goto finished_axesscan;
+                  else
+                    boxp->Bhalferror = B;
+                }
+            }
+        }
+    }
+ finished_axesscan:
+#else
+
+  boxp->Rhalferror = Rmin + (Rmax - Rmin + 1) / 2;
+  boxp->Ghalferror = Gmin + (Gmax - Gmin + 1) / 2;
+  boxp->Bhalferror = Bmin + (Bmax - Bmin + 1) / 2;
+
+  if (dist0 && dist1 && dist2)
+    {
+      AxisType longest_ax      = AXIS_UNDEF;
+      gint     longest_length  = 0;
+      gint     longest_length2 = 0;
+      gint     ratio;
+
+      /*
+        fprintf(stderr, "[%d,%d,%d=%d,%d,%d] ",
+        (Rmax - Rmin), (Gmax - Gmin), (Bmax - Bmin),
+        dist0, dist1, dist2);
+      */
+
+      if (dist0 >= longest_length)
+        {
+          longest_length2 = longest_length;
+          longest_length = dist0;
+          longest_ax = AXIS_RED;
+        }
+      else if (dist0 >= longest_length2)
+        {
+          longest_length2 = dist0;
+        }
+
+      if (dist1 >= longest_length)
+        {
+          longest_length2 = longest_length;
+          longest_length = dist1;
+          longest_ax = AXIS_GREEN;
+        }
+      else if (dist1 >= longest_length2)
+        {
+          longest_length2 = dist1;
+        }
+
+      if (dist2 >= longest_length)
+        {
+          longest_length2 = longest_length;
+          longest_length = dist2;
+          longest_ax = AXIS_BLUE;
+        }
+      else if (dist2 >= longest_length2)
+        {
+          longest_length2 = dist2;
+        }
+
+      if (longest_length2 == 0)
+        longest_length2 = 1;
+
+      ratio = (longest_length + longest_length2/2) / longest_length2;
+      /* fprintf(stderr, " ratio:(%d/%d)=%d ", longest_length, longest_length2, ratio);
+         fprintf(stderr, "C%d ", cells_remaining); */
+
+      if (ratio > cells_remaining + 1)
+        ratio = cells_remaining + 1;
+
+      if (ratio > 2)
+        {
+          switch (longest_ax)
+            {
+            case AXIS_RED:
+              if (Rmin + (Rmax - Rmin + ratio / 2) / ratio < Rmax)
+                {
+                  /* fprintf(stderr, "FR%d \007\n",ratio);*/
+                  boxp->Rhalferror = Rmin +  (Rmax - Rmin + ratio / 2) / ratio;
+                }
+              break;
+            case AXIS_GREEN:
+              if (Gmin + (Gmax - Gmin + ratio / 2) / ratio < Gmax)
+                {
+                  /* fprintf(stderr, "FG%d \007\n",ratio);*/
+                  boxp->Ghalferror = Gmin + (Gmax - Gmin + ratio / 2) / ratio;
+                }
+              break;
+            case AXIS_BLUE:
+              if (Bmin + (Bmax - Bmin + ratio / 2) / ratio < Bmax)
+                {
+                  /* fprintf(stderr, "FB%d \007\n",ratio);*/
+                  boxp->Bhalferror = Bmin + (Bmax - Bmin + ratio / 2) / ratio;
+                }
+              break;
+            default:
+              g_warning ("GRR, UNDEF LONGEST AXIS\007\n");
+            }
+        }
+    }
+
+  if (boxp->Rhalferror == Rmax)
+    boxp->Rhalferror = Rmin;
+  if (boxp->Ghalferror == Gmax)
+    boxp->Ghalferror = Gmin;
+  if (boxp->Bhalferror == Bmax)
+    boxp->Bhalferror = Bmin;
+
+  /*
+  boxp->Rhalferror = RSDF(dummyqo.cmap[0].red);
+  boxp->Ghalferror = GSDF(dummyqo.cmap[0].green);
+  boxp->Bhalferror = BSDF(dummyqo.cmap[0].blue);
+  */
+
+  /*
+  boxp->Rhalferror = (RSDF(dummyqo.cmap[0].red) + (Rmin+Rmax)/2)/2;
+  boxp->Ghalferror = (GSDF(dummyqo.cmap[0].green) + (Gmin+Gmax)/2)/2;
+  boxp->Bhalferror = (BSDF(dummyqo.cmap[0].blue) + (Bmin+Bmax)/2)/2;
+  */
+
+
+#endif
+  /*
+  fprintf(stderr, " %d,%d", dummyqo.cmap[0].blue, boxp->Bmax);
+
+  gimp_assert (boxp->Rhalferror >= boxp->Rmin);
+  gimp_assert (boxp->Rhalferror < boxp->Rmax);
+  gimp_assert (boxp->Ghalferror >= boxp->Gmin);
+  gimp_assert (boxp->Ghalferror < boxp->Gmax);
+  gimp_assert (boxp->Bhalferror >= boxp->Bmin);
+  gimp_assert (boxp->Bhalferror < boxp->Bmax);*/
+
+  /*boxp->error = (sqrt((double)(boxp->error/ccount)));*/
+  /*  boxp->rerror = (sqrt((double)((boxp->rerror)/ccount)));
+  boxp->gerror = (sqrt((double)((boxp->gerror)/ccount)));
+  boxp->berror = (sqrt((double)((boxp->berror)/ccount)));*/
+  /*printf(":%lld / %ld: ", boxp->error, ccount);
+  printf("(%d-%d-%d)(%d-%d-%d)(%d-%d-%d)\n",
+         Rmin, boxp->Rhalferror, Rmax,
+         Gmin, boxp->Ghalferror, Gmax,
+         Bmin, boxp->Bhalferror, Bmax
+         );
+         fflush(stdout);*/
+
+  boxp->colorcount = ccount;
+}
+
+
+/* Repeatedly select and split the largest box until we have enough
+ * boxes
+ */
+static gint
+median_cut_gray (CFHistogram histogram,
+                 boxptr      boxlist,
+                 gint        numboxes,
+                 gint        desired_colors)
+{
+  gint   lb;
+  boxptr b1, b2;
+
+  while (numboxes < desired_colors)
+    {
+      /* Select box to split.
+       * Current algorithm: by population for first half, then by volume.
+       */
+
+      b1 = find_biggest_volume (boxlist, numboxes);
+
+      if (b1 == NULL)           /* no splittable boxes left! */
+        break;
+
+      b2 = boxlist + numboxes;  /* where new box will go */
+      /* Copy the color bounds to the new box. */
+      b2->Rmax = b1->Rmax;
+      b2->Rmin = b1->Rmin;
+
+      /* Current algorithm: split at halfway point.
+       * (Since the box has been shrunk to minimum volume,
+       * any split will produce two nonempty subboxes.)
+       * Note that lb value is max for lower box, so must be < old max.
+       */
+      lb = (b1->Rmax + b1->Rmin) / 2;
+      b1->Rmax = lb;
+      b2->Rmin = lb + 1;
+
+      /* Update stats for boxes */
+      update_box_gray (histogram, b1);
+      update_box_gray (histogram, b2);
+      numboxes++;
+    }
+
+  return numboxes;
+}
+
+/* Repeatedly select and split the largest box until we have enough
+ * boxes
+ */
+static gint
+median_cut_rgb (CFHistogram   histogram,
+                boxptr        boxlist,
+                gint          numboxes,
+                gint          desired_colors,
+                GimpProgress *progress)
+{
+  gint     lb;
+  boxptr   b1, b2;
+  AxisType which_axis;
+
+  while (numboxes < desired_colors)
+    {
+      b1 = find_split_candidate (boxlist, numboxes, &which_axis, desired_colors);
+
+      if (b1 == NULL)           /* no splittable boxes left! */
+        break;
+
+      b2 = boxlist + numboxes;  /* where new box will go */
+      /* Copy the color bounds to the new box. */
+      b2->Rmax = b1->Rmax; b2->Gmax = b1->Gmax; b2->Bmax = b1->Bmax;
+      b2->Rmin = b1->Rmin; b2->Gmin = b1->Gmin; b2->Bmin = b1->Bmin;
+
+
+      /* Choose split point along selected axis, and update box bounds.
+       * Note that lb value is max for lower box, so must be < old max.
+       */
+      switch (which_axis)
+        {
+        case AXIS_RED:
+          lb = b1->Rhalferror;/* *0 + (b1->Rmax + b1->Rmin) / 2; */
+          b1->Rmax = lb;
+          b2->Rmin = lb+1;
+          g_return_val_if_fail (b1->Rmax >= b1->Rmin, numboxes);
+          g_return_val_if_fail (b2->Rmax >= b2->Rmin, numboxes);
+          break;
+        case AXIS_GREEN:
+          lb = b1->Ghalferror;/* *0 + (b1->Gmax + b1->Gmin) / 2; */
+          b1->Gmax = lb;
+          b2->Gmin = lb+1;
+          g_return_val_if_fail (b1->Gmax >= b1->Gmin, numboxes);
+          g_return_val_if_fail (b2->Gmax >= b2->Gmin, numboxes);
+          break;
+        case AXIS_BLUE:
+          lb = b1->Bhalferror;/* *0 + (b1->Bmax + b1->Bmin) / 2; */
+          b1->Bmax = lb;
+          b2->Bmin = lb+1;
+          g_return_val_if_fail (b1->Bmax >= b1->Bmin, numboxes);
+          g_return_val_if_fail (b2->Bmax >= b2->Bmin, numboxes);
+          break;
+        default:
+          g_error ("Uh-oh.");
+        }
+      /* Update stats for boxes */
+      numboxes++;
+
+      if (progress && (numboxes % 16 == 0))
+        gimp_progress_set_value (progress, (gdouble) numboxes / desired_colors);
+
+      update_box_rgb (histogram, b1, desired_colors - numboxes);
+      update_box_rgb (histogram, b2, desired_colors - numboxes);
+    }
+
+  return numboxes;
+}
+
+
+/* Compute representative color for a box, put it in colormap[icolor]
+ */
+static void
+compute_color_gray (QuantizeObj *quantobj,
+                    CFHistogram  histogram,
+                    boxptr       boxp,
+                    int          icolor)
+{
+  gint    i, min, max;
+  guint64 count;
+  guint64 total;
+  guint64 gtotal;
+
+  min = boxp->Rmin;
+  max = boxp->Rmax;
+
+  total = 0;
+  gtotal = 0;
+
+  for (i = min; i <= max; i++)
+    {
+      count = histogram[i];
+      if (count != 0)
+        {
+          total += count;
+          gtotal += i * count;
+        }
+    }
+
+  if (total != 0)
+    {
+      quantobj->cmap[icolor].red   =
+      quantobj->cmap[icolor].green =
+      quantobj->cmap[icolor].blue  = (gtotal + (total >> 1)) / total;
+    }
+  else
+    {
+      /* The only situation where total==0 is if the image was null or
+       *  all-transparent.  In that case we just put a dummy value in
+       *  the colormap.
+       */
+      quantobj->cmap[icolor].red   =
+      quantobj->cmap[icolor].green =
+      quantobj->cmap[icolor].blue  = 0;
+    }
+}
+
+
+/* Compute representative color for a box, put it in colormap[icolor]
+ */
+static void
+compute_color_rgb (QuantizeObj *quantobj,
+                   CFHistogram  histogram,
+                   boxptr       boxp,
+                   int          icolor)
+{
+  /* Current algorithm: mean weighted by pixels (not colors) */
+  /* Note it is important to get the rounding correct! */
+  gint      R, G, B;
+  gint      Rmin, Rmax;
+  gint      Gmin, Gmax;
+  gint      Bmin, Bmax;
+  ColorFreq total  = 0;
+  ColorFreq Rtotal = 0;
+  ColorFreq Gtotal = 0;
+  ColorFreq Btotal = 0;
+
+  Rmin = boxp->Rmin;  Rmax = boxp->Rmax;
+  Gmin = boxp->Gmin;  Gmax = boxp->Gmax;
+  Bmin = boxp->Bmin;  Bmax = boxp->Bmax;
+
+  for (R = Rmin; R <= Rmax; R++)
+    for (G = Gmin; G <= Gmax; G++)
+      {
+        for (B = Bmin; B <= Bmax; B++)
+          {
+            ColorFreq this_freq = *HIST_LIN (histogram, R, G, B);
+
+            if (this_freq != 0)
+              {
+                total += this_freq;
+                Rtotal += R * this_freq;
+                Gtotal += G * this_freq;
+                Btotal += B * this_freq;
+              }
+          }
+      }
+
+  if (total > 0)
+    {
+      guchar red, green, blue;
+
+      lin_to_rgb (/*(Rtotal + (total>>1)) / total,
+                    (Gtotal + (total>>1)) / total,
+                    (Btotal + (total>>1)) / total,*/
+                  (double)Rtotal / (double)total,
+                  (double)Gtotal / (double)total,
+                  (double)Btotal / (double)total,
+                  &red, &green, &blue);
+
+      quantobj->cmap[icolor].red   = red;
+      quantobj->cmap[icolor].green = green;
+      quantobj->cmap[icolor].blue  = blue;
+    }
+  else
+    {
+      /* The only situation where total==0 is if the image was null or
+       *  all-transparent.  In that case we just put a dummy value in
+       *  the colormap.
+       */
+      quantobj->cmap[icolor].red   = 0;
+      quantobj->cmap[icolor].green = 0;
+      quantobj->cmap[icolor].blue  = 0;
+    }
+}
+
+
+/* Compute representative color for a box, put it in colormap[icolor]
+ */
+static void
+compute_color_lin8 (QuantizeObj *quantobj,
+                    CFHistogram  histogram,
+                    boxptr       boxp,
+                    const gint   icolor)
+{
+  /* Current algorithm: mean weighted by pixels (not colors) */
+  /* Note it is important to get the rounding correct! */
+  gint      R, G, B;
+  gint      Rmin, Rmax;
+  gint      Gmin, Gmax;
+  gint      Bmin, Bmax;
+  ColorFreq total  = 0;
+  ColorFreq Rtotal = 0;
+  ColorFreq Gtotal = 0;
+  ColorFreq Btotal = 0;
+
+  Rmin = boxp->Rmin;  Rmax = boxp->Rmax;
+  Gmin = boxp->Gmin;  Gmax = boxp->Gmax;
+  Bmin = boxp->Bmin;  Bmax = boxp->Bmax;
+
+  for (R = Rmin; R <= Rmax; R++)
+    for (G = Gmin; G <= Gmax; G++)
+      {
+        for (B = Bmin; B <= Bmax; B++)
+          {
+            ColorFreq this_freq = *HIST_LIN (histogram, R, G, B);
+
+            if (this_freq != 0)
+              {
+                Rtotal += R * this_freq;
+                Gtotal += G * this_freq;
+                Btotal += B * this_freq;
+                total += this_freq;
+              }
+          }
+      }
+
+  if (total != 0)
+    {
+      quantobj->cmap[icolor].red   = ((Rtotal << R_SHIFT) + (total>>1)) / total;
+      quantobj->cmap[icolor].green = ((Gtotal << G_SHIFT) + (total>>1)) / total;
+      quantobj->cmap[icolor].blue  = ((Btotal << B_SHIFT) + (total>>1)) / total;
+    }
+  else
+    {
+      /* The only situation where total==0 is if the image was null or
+       *  all-transparent.  In that case we just put a dummy value in
+       *  the colormap.
+       */
+      g_warning ("eep.");
+      quantobj->cmap[icolor].red   = 0;
+      quantobj->cmap[icolor].green = 128;
+      quantobj->cmap[icolor].blue  = 128;
+    }
+}
+
+
+/* Master routine for color selection
+ */
+static void
+select_colors_gray (QuantizeObj *quantobj,
+                    CFHistogram  histogram)
+{
+  boxptr boxlist;
+  gint   numboxes;
+  gint   desired = quantobj->desired_number_of_colors;
+  gint   i;
+
+  /* Allocate workspace for box list */
+  boxlist = g_new (box, desired);
+
+  /* Initialize one box containing whole space */
+  numboxes = 1;
+  boxlist[0].Rmin = 0;
+  boxlist[0].Rmax = 255;
+  /* Shrink it to actually-used volume and set its statistics */
+  update_box_gray (histogram, boxlist);
+  /* Perform median-cut to produce final box list */
+  numboxes = median_cut_gray (histogram, boxlist, numboxes, desired);
+
+  quantobj->actual_number_of_colors = numboxes;
+  /* Compute the representative color for each box, fill colormap */
+  for (i = 0; i < numboxes; i++)
+    compute_color_gray (quantobj, histogram, boxlist + i, i);
+}
+
+
+/* Master routine for color selection
+ */
+static void
+select_colors_rgb (QuantizeObj *quantobj,
+                   CFHistogram  histogram)
+{
+  boxptr boxlist;
+  gint   numboxes;
+  gint   desired = quantobj->desired_number_of_colors;
+  gint  i;
+
+  /* Allocate workspace for box list */
+  boxlist = g_new (box, desired);
+
+  /* Initialize one box containing whole space */
+  numboxes = 1;
+  boxlist[0].Rmin = 0;
+  boxlist[0].Rmax = HIST_R_ELEMS - 1;
+  boxlist[0].Gmin = 0;
+  boxlist[0].Gmax = HIST_G_ELEMS - 1;
+  boxlist[0].Bmin = 0;
+  boxlist[0].Bmax = HIST_B_ELEMS - 1;
+  /* Shrink it to actually-used volume and set its statistics */
+  update_box_rgb (histogram, &boxlist[0], quantobj->desired_number_of_colors);
+  /* Perform median-cut to produce final box list */
+  numboxes = median_cut_rgb (histogram, boxlist, numboxes, desired,
+                             quantobj->progress);
+
+  quantobj->actual_number_of_colors = numboxes;
+  /* Compute the representative color for each box, fill colormap */
+  for (i = 0; i < numboxes; i++)
+    {
+      compute_color_rgb (quantobj, histogram, &boxlist[i], i);
+    }
+
+  g_free (boxlist);
+}
+
+
+/*
+ * These routines are concerned with the time-critical task of mapping input
+ * colors to the nearest color in the selected colormap.
+ *
+ * We re-use the histogram space as an "inverse color map", essentially a
+ * cache for the results of nearest-color searches.  All colors within a
+ * histogram cell will be mapped to the same colormap entry, namely the one
+ * closest to the cell's center.  This may not be quite the closest entry to
+ * the actual input color, but it's almost as good.  A zero in the cache
+ * indicates we haven't found the nearest color for that cell yet; the array
+ * is cleared to zeroes before starting the mapping pass.  When we find the
+ * nearest color for a cell, its colormap index plus one is recorded in the
+ * cache for future use.  The pass2 scanning routines call fill_inverse_cmap
+ * when they need to use an unfilled entry in the cache.
+ *
+ * Our method of efficiently finding nearest colors is based on the "locally
+ * sorted search" idea described by Heckbert and on the incremental distance
+ * calculation described by Spencer W. Thomas in chapter III.1 of Graphics
+ * Gems II (James Arvo, ed.  Academic Press, 1991).  Thomas points out that
+ * the distances from a given colormap entry to each cell of the histogram can
+ * be computed quickly using an incremental method: the differences between
+ * distances to adjacent cells themselves differ by a constant.  This allows a
+ * fairly fast implementation of the "brute force" approach of computing the
+ * distance from every colormap entry to every histogram cell.  Unfortunately,
+ * it needs a work array to hold the best-distance-so-far for each histogram
+ * cell (because the inner loop has to be over cells, not colormap entries).
+ * The work array elements have to be ints, so the work array would need
+ * 256Kb at our recommended precision.  This is not feasible in DOS machines.
+ *
+ * To get around these problems, we apply Thomas' method to compute the
+ * nearest colors for only the cells within a small subbox of the histogram.
+ * The work array need be only as big as the subbox, so the memory usage
+ * problem is solved.  Furthermore, we need not fill subboxes that are never
+ * referenced in pass2; many images use only part of the color gamut, so a
+ * fair amount of work is saved.  An additional advantage of this
+ * approach is that we can apply Heckbert's locality criterion to quickly
+ * eliminate colormap entries that are far away from the subbox; typically
+ * three-fourths of the colormap entries are rejected by Heckbert's criterion,
+ * and we need not compute their distances to individual cells in the subbox.
+ * The speed of this approach is heavily influenced by the subbox size: too
+ * small means too much overhead, too big loses because Heckbert's criterion
+ * can't eliminate as many colormap entries.  Empirically the best subbox
+ * size seems to be about 1/512th of the histogram (1/8th in each direction).
+ *
+ * Thomas' article also describes a refined method which is asymptotically
+ * faster than the brute-force method, but it is also far more complex and
+ * cannot efficiently be applied to small subboxes.  It is therefore not
+ * useful for programs intended to be portable to DOS machines.  On machines
+ * with plenty of memory, filling the whole histogram in one shot with Thomas'
+ * refined method might be faster than the present code --- but then again,
+ * it might not be any faster, and it's certainly more complicated.
+ */
+
+
+/* log2(histogram cells in update box) for each axis; this can be adjusted */
+/*#define BOX_R_LOG  (PRECISION_R-3)
+  #define BOX_G_LOG  (PRECISION_G-3)
+  #define BOX_B_LOG  (PRECISION_B-3)*/
+
+/*adam*/
+#define BOX_R_LOG 0
+#define BOX_G_LOG 0
+#define BOX_B_LOG 0
+
+#define BOX_R_ELEMS  (1<<BOX_R_LOG) /* # of hist cells in update box */
+#define BOX_G_ELEMS  (1<<BOX_G_LOG)
+#define BOX_B_ELEMS  (1<<BOX_B_LOG)
+
+#define BOX_R_SHIFT  (R_SHIFT + BOX_R_LOG)
+#define BOX_G_SHIFT  (G_SHIFT + BOX_G_LOG)
+#define BOX_B_SHIFT  (B_SHIFT + BOX_B_LOG)
+
+
+/*
+ * The next three routines implement inverse colormap filling.  They
+ * could all be folded into one big routine, but splitting them up
+ * this way saves some stack space (the mindist[] and bestdist[]
+ * arrays need not coexist) and may allow some compilers to produce
+ * better code by registerizing more inner-loop variables.
+ */
+
+/* Locate the colormap entries close enough to an update box to be
+ * candidates for the nearest entry to some cell(s) in the update box.
+ * The update box is specified by the center coordinates of its first
+ * cell.  The number of candidate colormap entries is returned, and
+ * their colormap indexes are placed in colorlist[].
+ *
+ * This routine uses Heckbert's "locally sorted search" criterion to
+ * select the colors that need further consideration.
+ */
+static gint
+find_nearby_colors (QuantizeObj *quantobj,
+                    int          minR,
+                    int          minG,
+                    int          minB,
+                    int          colorlist[])
+{
+  int numcolors = quantobj->actual_number_of_colors;
+  int maxR, maxG, maxB;
+  int centerR, centerG, centerB;
+  int i, x, ncolors;
+  int minmaxdist, min_dist, max_dist, tdist;
+  int mindist[MAXNUMCOLORS];    /* min distance to colormap entry i */
+
+  /* Compute true coordinates of update box's upper corner and center.
+   * Actually we compute the coordinates of the center of the upper-corner
+   * histogram cell, which are the upper bounds of the volume we care about.
+   * Note that since ">>" rounds down, the "center" values may be closer to
+   * min than to max; hence comparisons to them must be "<=", not "<".
+   */
+  maxR = minR + ((1 << BOX_R_SHIFT) - (1 << R_SHIFT));
+  centerR = (minR + maxR + 1) >> 1;
+  maxG = minG + ((1 << BOX_G_SHIFT) - (1 << G_SHIFT));
+  centerG = (minG + maxG + 1) >> 1;
+  maxB = minB + ((1 << BOX_B_SHIFT) - (1 << B_SHIFT));
+  centerB = (minB + maxB + 1) >> 1;
+
+  /* For each color in colormap, find:
+   *  1. its minimum squared-distance to any point in the update box
+   *     (zero if color is within update box);
+   *  2. its maximum squared-distance to any point in the update box.
+   * Both of these can be found by considering only the corners of the box.
+   * We save the minimum distance for each color in mindist[];
+   * only the smallest maximum distance is of interest.
+   */
+  minmaxdist = 0x7FFFFFFFL;
+
+  for (i = 0; i < numcolors; i++)
+    {
+      /* We compute the squared-R-distance term, then add in the other two. */
+      x = quantobj->clin[i].red;
+      if (x < minR)
+        {
+          tdist = (x - minR) * R_SCALE;
+          min_dist = tdist*tdist;
+          tdist = (x - maxR) * R_SCALE;
+          max_dist = tdist*tdist;
+        }
+      else if (x > maxR)
+        {
+          tdist = (x - maxR) * R_SCALE;
+          min_dist = tdist*tdist;
+          tdist = (x - minR) * R_SCALE;
+          max_dist = tdist*tdist;
+        }
+      else
+        {
+          /* within cell range so no contribution to min_dist */
+          min_dist = 0;
+          if (x <= centerR)
+            {
+              tdist = (x - maxR) * R_SCALE;
+              max_dist = tdist*tdist;
+            }
+          else
+            {
+              tdist = (x - minR) * R_SCALE;
+              max_dist = tdist*tdist;
+            }
+        }
+
+      x = quantobj->clin[i].green;
+      if (x < minG)
+        {
+          tdist = (x - minG) * G_SCALE;
+          min_dist += tdist*tdist;
+          tdist = (x - maxG) * G_SCALE;
+          max_dist += tdist*tdist;
+        }
+      else if (x > maxG)
+        {
+          tdist = (x - maxG) * G_SCALE;
+          min_dist += tdist*tdist;
+          tdist = (x - minG) * G_SCALE;
+          max_dist += tdist*tdist;
+        }
+      else
+        {
+          /* within cell range so no contribution to min_dist */
+          if (x <= centerG)
+            {
+              tdist = (x - maxG) * G_SCALE;
+              max_dist += tdist*tdist;
+            }
+          else
+            {
+              tdist = (x - minG) * G_SCALE;
+              max_dist += tdist*tdist;
+            }
+        }
+
+      x = quantobj->clin[i].blue;
+      if (x < minB)
+        {
+          tdist = (x - minB) * B_SCALE;
+          min_dist += tdist*tdist;
+          tdist = (x - maxB) * B_SCALE;
+          max_dist += tdist*tdist;
+        }
+      else if (x > maxB)
+        {
+          tdist = (x - maxB) * B_SCALE;
+          min_dist += tdist*tdist;
+          tdist = (x - minB) * B_SCALE;
+          max_dist += tdist*tdist;
+        }
+      else
+        {
+          /* within cell range so no contribution to min_dist */
+          if (x <= centerB)
+            {
+              tdist = (x - maxB) * B_SCALE;
+              max_dist += tdist*tdist;
+            }
+          else
+            {
+              tdist = (x - minB) * B_SCALE;
+              max_dist += tdist*tdist;
+            }
+        }
+
+      mindist[i] = min_dist;      /* save away the results */
+      if (max_dist < minmaxdist)
+        minmaxdist = max_dist;
+    }
+
+  /* Now we know that no cell in the update box is more than minmaxdist
+   * away from some colormap entry.  Therefore, only colors that are
+   * within minmaxdist of some part of the box need be considered.
+   */
+  ncolors = 0;
+  for (i = 0; i < numcolors; i++)
+    {
+      if (mindist[i] <= minmaxdist)
+        colorlist[ncolors++] = i;
+    }
+
+  return ncolors;
+}
+
+
+/* Find the closest colormap entry for each cell in the update box,
+ * given the list of candidate colors prepared by find_nearby_colors.
+ * Return the indexes of the closest entries in the bestcolor[] array.
+ * This routine uses Thomas' incremental distance calculation method
+ * to find the distance from a colormap entry to successive cells in
+ * the box.
+ */
+static void
+find_best_colors (QuantizeObj *quantobj,
+                  gint         minR,
+                  gint         minG,
+                  gint         minB,
+                  gint         numcolors,
+                  gint         colorlist[],
+                  gint         bestcolor[])
+{
+  gint  iR, iG, iB;
+  gint  i, icolor;
+  gint *bptr;           /* pointer into bestdist[] array */
+  gint *cptr;           /* pointer into bestcolor[] array */
+  gint  dist0, dist1;     /* initial distance values */
+  gint  dist2;            /* current distance in inner loop */
+  gint  xx0, xx1;         /* distance increments */
+  gint  xx2;
+  gint  inR, inG, inB;    /* initial values for increments */
+
+  /* This array holds the distance to the nearest-so-far color for each cell */
+  gint  bestdist[BOX_R_ELEMS * BOX_G_ELEMS * BOX_B_ELEMS] = { 0, };
+
+  /* Initialize best-distance for each cell of the update box */
+  bptr = bestdist;
+  for (i = BOX_R_ELEMS*BOX_G_ELEMS*BOX_B_ELEMS-1; i >= 0; i--)
+    *bptr++ = 0x7FFFFFFFL;
+
+  /* For each color selected by find_nearby_colors,
+   * compute its distance to the center of each cell in the box.
+   * If that's less than best-so-far, update best distance and color number.
+   */
+
+  /* Nominal steps between cell centers ("x" in Thomas article) */
+#define STEP_R  ((1 << R_SHIFT) * R_SCALE)
+#define STEP_G  ((1 << G_SHIFT) * G_SCALE)
+#define STEP_B  ((1 << B_SHIFT) * B_SCALE)
+
+  for (i = 0; i < numcolors; i++)
+    {
+      icolor = colorlist[i];
+      /* Compute (square of) distance from minR/G/B to this color */
+      inR = (minR - quantobj->clin[icolor].red) * R_SCALE;
+      dist0 = inR*inR;
+      /* special-case for L*==0: chroma diffs irrelevant */
+      /*    if (minR > 0 || quantobj->clin[icolor].red > 0) */
+      {
+        inG = (minG - quantobj->clin[icolor].green) * G_SCALE;
+        dist0 += inG*inG;
+        inB = (minB - quantobj->clin[icolor].blue) * B_SCALE;
+        dist0 += inB*inB;
+      }
+      /*    else
+            {
+            inG = 0;
+            inB = 0;
+            } */
+      /* Form the initial difference increments */
+      inR = inR * (2 * STEP_R) + STEP_R * STEP_R;
+      inG = inG * (2 * STEP_G) + STEP_G * STEP_G;
+      inB = inB * (2 * STEP_B) + STEP_B * STEP_B;
+      /* Now loop over all cells in box, updating distance per Thomas method */
+      bptr = bestdist;
+      cptr = bestcolor;
+      xx0 = inR;
+      for (iR = BOX_R_ELEMS-1; iR >= 0; iR--)
+        {
+          dist1 = dist0;
+          xx1 = inG;
+          for (iG = BOX_G_ELEMS-1; iG >= 0; iG--)
+            {
+              dist2 = dist1;
+              xx2 = inB;
+              for (iB = BOX_B_ELEMS-1; iB >= 0; iB--)
+                {
+                  if (dist2 < *bptr)
+                    {
+                      *bptr = dist2;
+                      *cptr = icolor;
+                    }
+                  dist2 += xx2;
+                  xx2 += 2 * STEP_B * STEP_B;
+                  bptr++;
+                  cptr++;
+                }
+              dist1 += xx1;
+              xx1 += 2 * STEP_G * STEP_G;
+            }
+          dist0 += xx0;
+          xx0 += 2 * STEP_R * STEP_R;
+        }
+    }
+}
+
+
+/* Fill the inverse-colormap entries in the update box that contains
+ * histogram cell R/G/B.  (Only that one cell MUST be filled, but we
+ * can fill as many others as we wish.)
+ */
+static void
+fill_inverse_cmap_gray (QuantizeObj *quantobj,
+                        CFHistogram  histogram,
+                        gint         pixel)
+{
+  Color *cmap = quantobj->cmap;
+  gint64 mindist;
+  gint   mindisti;
+  gint   i;
+
+  g_return_if_fail (quantobj->actual_number_of_colors > 0);
+
+  mindist  = G_MAXLONG;
+  mindisti = -1;
+
+  for (i = 0; i < quantobj->actual_number_of_colors; i++)
+    {
+      gint64 dist = ABS (pixel - cmap[i].red);
+
+      if (dist < mindist)
+        {
+          mindist  = dist;
+          mindisti = i;
+
+          if (mindist == 0)
+            break;
+        }
+    }
+
+  histogram[pixel] = mindisti + 1;
+}
+
+
+/* Fill the inverse-colormap entries in the update box that contains
+ * histogram cell R/G/B.  (Only that one cell MUST be filled, but we
+ * can fill as many others as we wish.)
+ */
+static void
+fill_inverse_cmap_rgb (QuantizeObj *quantobj,
+                       CFHistogram  histogram,
+                       gint         R,
+                       gint         G,
+                       gint         B)
+{
+  gint  minR, minG, minB; /* lower left corner of update box */
+  gint  iR, iG, iB;
+  gint *cptr;           /* pointer into bestcolor[] array */
+  /* This array lists the candidate colormap indexes. */
+  gint  colorlist[MAXNUMCOLORS];
+  gint  numcolors;                /* number of candidate colors */
+  /* This array holds the actually closest colormap index for each cell. */
+  gint  bestcolor[BOX_R_ELEMS * BOX_G_ELEMS * BOX_B_ELEMS] = { 0, };
+
+  /* Convert cell coordinates to update box id */
+  R >>= BOX_R_LOG;
+  G >>= BOX_G_LOG;
+  B >>= BOX_B_LOG;
+
+  /* Compute true coordinates of update box's origin corner.
+   * Actually we compute the coordinates of the center of the corner
+   * histogram cell, which are the lower bounds of the volume we care about.
+   */
+  minR = (R << BOX_R_SHIFT) + ((1 << R_SHIFT) >> 1);
+  minG = (G << BOX_G_SHIFT) + ((1 << G_SHIFT) >> 1);
+  minB = (B << BOX_B_SHIFT) + ((1 << B_SHIFT) >> 1);
+
+  /* Determine which colormap entries are close enough to be candidates
+   * for the nearest entry to some cell in the update box.
+   */
+  numcolors = find_nearby_colors (quantobj, minR, minG, minB, colorlist);
+
+  /* Determine the actually nearest colors. */
+  find_best_colors (quantobj, minR, minG, minB, numcolors, colorlist,
+                    bestcolor);
+
+  /* Save the best color numbers (plus 1) in the main cache array */
+  R <<= BOX_R_LOG;              /* convert id back to base cell indexes */
+  G <<= BOX_G_LOG;
+  B <<= BOX_B_LOG;
+  cptr = bestcolor;
+  for (iR = 0; iR < BOX_R_ELEMS; iR++)
+    {
+      for (iG = 0; iG < BOX_G_ELEMS; iG++)
+        {
+          for (iB = 0; iB < BOX_B_ELEMS; iB++)
+            {
+              *HIST_LIN (histogram, R + iR, G + iG, B + iB) = (*cptr++) + 1;
+            }
+        }
+    }
+}
+
+
+/*  This is pass 1  */
+
+static void
+median_cut_pass1_gray (QuantizeObj *quantobj)
+{
+  select_colors_gray (quantobj, quantobj->histogram);
+}
+
+static void
+snap_to_black_and_white (QuantizeObj *quantobj)
+{
+  /* find whitest and blackest colors in palette, if they are closer
+   * than 24 units of euclidian distance in sRGB snap them to pure
+   * black / white.
+   */
+#define POW2(a) ((a)*(a))
+  gint   desired  = quantobj->desired_number_of_colors;
+  gint   whitest  = 0;
+  gint   blackest = 0;
+
+  gint64 white_dist = POW2(255) * 3;
+  gint64 black_dist = POW2(255) * 3;
+  gint   i;
+
+  for (i = 0; i < desired; i ++)
+    {
+       int dist;
+
+       dist = POW2 (quantobj->cmap[i].red   - 255) +
+              POW2 (quantobj->cmap[i].green - 255) +
+              POW2( quantobj->cmap[i].blue  - 255);
+       if (dist < white_dist)
+         {
+           white_dist = dist;
+           whitest = i;
+         }
+
+       dist = POW2(quantobj->cmap[i].red   - 0) +
+              POW2(quantobj->cmap[i].green - 0) +
+              POW2(quantobj->cmap[i].blue  - 0);
+       if (dist < black_dist)
+         {
+           black_dist = dist;
+           blackest = i;
+         }
+    }
+
+  if (desired > 2 &&
+      had_white   &&
+      white_dist < POW2(128))
+  {
+     quantobj->cmap[whitest].red   =
+     quantobj->cmap[whitest].green =
+     quantobj->cmap[whitest].blue  = 255;
+  }
+  if (desired > 2 &&
+      had_black   &&
+      black_dist < POW2(128))
+  {
+     quantobj->cmap[blackest].red   =
+     quantobj->cmap[blackest].green =
+     quantobj->cmap[blackest].blue  = 0;
+  }
+#undef POW2
+}
+
+static void
+median_cut_pass1_rgb (QuantizeObj *quantobj)
+{
+  select_colors_rgb (quantobj, quantobj->histogram);
+  snap_to_black_and_white (quantobj);
+}
+
+
+static void
+monopal_pass1 (QuantizeObj *quantobj)
+{
+  quantobj->actual_number_of_colors = 2;
+
+  quantobj->cmap[0].red   = 0;
+  quantobj->cmap[0].green = 0;
+  quantobj->cmap[0].blue  = 0;
+  quantobj->cmap[1].red   = 255;
+  quantobj->cmap[1].green = 255;
+  quantobj->cmap[1].blue  = 255;
+}
+
+static void
+webpal_pass1 (QuantizeObj *quantobj)
+{
+  int i;
+
+  quantobj->actual_number_of_colors = 216;
+
+  for (i=0; i < 216; i++)
+    {
+      quantobj->cmap[i].red   = webpal[i * 3];
+      quantobj->cmap[i].green = webpal[i * 3 +1];
+      quantobj->cmap[i].blue  = webpal[i * 3 +2];
+    }
+}
+
+static void
+custompal_pass1 (QuantizeObj *quantobj)
+{
+  gint   i;
+  GList *list;
+
+  /* fprintf(stderr,
+             "custompal_pass1: using (theCustomPalette %s) from (file %s)\n",
+             theCustomPalette->name, theCustomPalette->filename); */
+
+  for (i = 0, list = gimp_palette_get_colors (quantobj->custom_palette);
+       list;
+       i++, list = g_list_next (list))
+    {
+      GimpPaletteEntry *entry = list->data;
+      guchar            r, g, b;
+
+      gimp_rgb_get_uchar (&entry->color, &r, &g, &b);
+
+      quantobj->cmap[i].red   = (gint) r;
+      quantobj->cmap[i].green = (gint) g;
+      quantobj->cmap[i].blue  = (gint) b;
+    }
+
+  quantobj -> actual_number_of_colors = i;
+}
+
+/*
+ * Map some rows of pixels to the output colormapped representation.
+ */
+
+static void
+median_cut_pass2_no_dither_gray (QuantizeObj *quantobj,
+                                 GimpLayer   *layer,
+                                 GeglBuffer  *new_buffer)
+{
+  GeglBufferIterator *iter;
+  CFHistogram         histogram = quantobj->histogram;
+  ColorFreq          *cachep;
+  const Babl         *src_format;
+  const Babl         *dest_format;
+  GeglRectangle      *src_roi;
+  gint                src_bpp;
+  gint                dest_bpp;
+  gint                has_alpha;
+  guint64            *index_used_count = quantobj->index_used_count;
+  gboolean            dither_alpha     = quantobj->want_dither_alpha;
+  gint                offsetx, offsety;
+
+  gimp_item_get_offset (GIMP_ITEM (layer), &offsetx, &offsety);
+
+  src_format  = gimp_drawable_get_format (GIMP_DRAWABLE (layer));
+  dest_format = gegl_buffer_get_format (new_buffer);
+
+  src_bpp  = babl_format_get_bytes_per_pixel (src_format);
+  dest_bpp = babl_format_get_bytes_per_pixel (dest_format);
+
+  has_alpha = babl_format_has_alpha (src_format);
+
+  iter = gegl_buffer_iterator_new (gimp_drawable_get_buffer (GIMP_DRAWABLE (layer)),
+                                   NULL, 0, NULL,
+                                   GEGL_ACCESS_READ, GEGL_ABYSS_NONE, 2);
+  src_roi = &iter->items[0].roi;
+
+  gegl_buffer_iterator_add (iter, new_buffer,
+                            NULL, 0, NULL,
+                            GEGL_ACCESS_WRITE, GEGL_ABYSS_NONE);
+
+  while (gegl_buffer_iterator_next (iter))
+    {
+      const guchar *src  = iter->items[0].data;
+      guchar       *dest = iter->items[1].data;
+      gint          row;
+
+      for (row = 0; row < src_roi->height; row++)
+        {
+          gint col;
+
+          for (col = 0; col < src_roi->width; col++)
+            {
+              /* get pixel value and index into the cache */
+              gint pixel = src[GRAY];
+
+              cachep = &histogram[pixel];
+              /* If we have not seen this color before, find nearest
+               * colormap entry and update the cache
+               */
+              if (*cachep == 0)
+                fill_inverse_cmap_gray (quantobj, histogram, pixel);
+
+              if (has_alpha)
+                {
+                  gboolean transparent = FALSE;
+
+                  if (dither_alpha)
+                    {
+                      gint dither_x = (col + offsetx + src_roi->x) & DM_WIDTHMASK;
+                      gint dither_y = (row + offsety + src_roi->y) & DM_HEIGHTMASK;
+
+                      if ((src[ALPHA_G]) < DM[dither_x][dither_y])
+                        transparent = TRUE;
+                    }
+                  else
+                    {
+                      if (src[ALPHA_G] <= 127)
+                        transparent = TRUE;
+                    }
+
+                  if (transparent)
+                    {
+                      dest[ALPHA_I] = 0;
+                    }
+                  else
+                    {
+                      dest[ALPHA_I] = 255;
+                      index_used_count[dest[INDEXED] = *cachep - 1]++;
+                    }
+                }
+              else
+                {
+                  /* Now emit the colormap index for this cell */
+                  index_used_count[dest[INDEXED] = *cachep - 1]++;
+                }
+
+              src  += src_bpp;
+              dest += dest_bpp;
+            }
+        }
+    }
+}
+
+static void
+median_cut_pass2_fixed_dither_gray (QuantizeObj *quantobj,
+                                    GimpLayer   *layer,
+                                    GeglBuffer  *new_buffer)
+{
+  GeglBufferIterator *iter;
+  CFHistogram         histogram = quantobj->histogram;
+  ColorFreq          *cachep;
+  const Babl         *src_format;
+  const Babl         *dest_format;
+  GeglRectangle      *src_roi;
+  gint                src_bpp;
+  gint                dest_bpp;
+  gboolean            has_alpha;
+  gint                pixval1 = 0;
+  gint                pixval2 = 0;
+  gint                err1;
+  gint                err2;
+  Color              *color1;
+  Color              *color2;
+  guint64            *index_used_count = quantobj->index_used_count;
+  gboolean            dither_alpha     = quantobj->want_dither_alpha;
+  gint                offsetx, offsety;
+
+  gimp_item_get_offset (GIMP_ITEM (layer), &offsetx, &offsety);
+
+  src_format  = gimp_drawable_get_format (GIMP_DRAWABLE (layer));
+  dest_format = gegl_buffer_get_format (new_buffer);
+
+  src_bpp  = babl_format_get_bytes_per_pixel (src_format);
+  dest_bpp = babl_format_get_bytes_per_pixel (dest_format);
+
+  has_alpha = babl_format_has_alpha (src_format);
+
+  iter = gegl_buffer_iterator_new (gimp_drawable_get_buffer (GIMP_DRAWABLE (layer)),
+                                   NULL, 0, NULL,
+                                   GEGL_ACCESS_READ, GEGL_ABYSS_NONE, 2);
+  src_roi = &iter->items[0].roi;
+
+  gegl_buffer_iterator_add (iter, new_buffer,
+                            NULL, 0, NULL,
+                            GEGL_ACCESS_WRITE, GEGL_ABYSS_NONE);
+
+  while (gegl_buffer_iterator_next (iter))
+    {
+      const guchar *src  = iter->items[0].data;
+      guchar       *dest = iter->items[1].data;
+      gint          row;
+
+      for (row = 0; row < src_roi->height; row++)
+        {
+          gint col;
+
+          for (col = 0; col < src_roi->width; col++)
+            {
+              gint       pixel;
+              const gint dmval =
+                DM[(col + offsetx + src_roi->x) & DM_WIDTHMASK]
+                [(row + offsety + src_roi->y) & DM_HEIGHTMASK];
+
+              /* get pixel value and index into the cache */
+              pixel = src[GRAY];
+
+              cachep = &histogram[pixel];
+              /* If we have not seen this color before, find nearest
+               * colormap entry and update the cache
+               */
+              if (*cachep == 0)
+                fill_inverse_cmap_gray (quantobj, histogram, pixel);
+
+              pixval1 = *cachep - 1;
+              color1 = &quantobj->cmap[pixval1];
+
+              if (quantobj->actual_number_of_colors > 2)
+                {
+                  const int re = src[GRAY] - (int)color1->red;
+                  int RV = src[GRAY] + re;
+
+                  do
+                    {
+                      const gint R = CLAMP0255 (RV);
+
+                      cachep = &histogram[R];
+                      /* If we have not seen this color before, find
+                       * nearest colormap entry and update the cache
+                       */
+                      if (*cachep == 0)
+                        fill_inverse_cmap_gray (quantobj, histogram, R);
+
+                      pixval2 = *cachep - 1;
+                      RV += re;
+                    }
+                  while ((pixval1 == pixval2) &&
+                         (! (RV>255 || RV<0) ) &&
+                         re);
+                }
+              else
+                {
+                  /* not enough colors to bother looking for an 'alternative'
+                     color (we may fail to do so anyway), so decide that
+                     the alternative color is simply the other cmap entry. */
+                  pixval2 = (pixval1 + 1) %
+                    (quantobj->actual_number_of_colors);
+                }
+
+              /* always deterministically sort pixval1 and pixval2, to
+                 avoid artifacts in the dither range due to inverting our
+                 relative color viewpoint -- most obvious in 1-bit dither. */
+              if (pixval1 > pixval2)
+                {
+                  gint tmpval = pixval1;
+                  pixval1 = pixval2;
+                  pixval2 = tmpval;
+                  color1 = &quantobj->cmap[pixval1];
+                }
+
+              color2 = &quantobj->cmap[pixval2];
+
+              err1 = ABS(color1->red - src[GRAY]);
+              err2 = ABS(color2->red - src[GRAY]);
+              if (err1 || err2)
+                {
+                  const int proportion2 = (256 * 255 * err2) / (err1 + err2);
+
+                  if ((dmval * 256) > proportion2)
+                    {
+                      pixval1 = pixval2; /* use color2 instead of color1*/
+                    }
+                }
+
+              if (has_alpha)
+                {
+                  gboolean transparent = FALSE;
+
+                  if (dither_alpha)
+                    {
+                      if (src[ALPHA_G] < dmval)
+                        transparent = TRUE;
+                    }
+                  else
+                    {
+                      if (src[ALPHA_G] <= 127)
+                        transparent = TRUE;
+                    }
+
+                  if (transparent)
+                    {
+                      dest[ALPHA_I] = 0;
+                    }
+                  else
+                    {
+                      dest[ALPHA_I] = 255;
+                      index_used_count[dest[INDEXED] = pixval1]++;
+                    }
+                }
+              else
+                {
+                  /* Now emit the colormap index for this cell, barfbarf */
+                  index_used_count[dest[INDEXED] = pixval1]++;
+                }
+
+              src  += src_bpp;
+              dest += dest_bpp;
+            }
+        }
+    }
+}
+
+static void
+median_cut_pass2_no_dither_rgb (QuantizeObj *quantobj,
+                                GimpLayer   *layer,
+                                GeglBuffer  *new_buffer)
+{
+  GeglBufferIterator *iter;
+  CFHistogram         histogram = quantobj->histogram;
+  ColorFreq          *cachep;
+  const Babl         *src_format;
+  const Babl         *dest_format;
+  GeglRectangle      *src_roi;
+  gint                src_bpp;
+  gint                dest_bpp;
+  gint                has_alpha;
+  gint                R, G, B;
+  gint                red_pix          = RED;
+  gint                green_pix        = GREEN;
+  gint                blue_pix         = BLUE;
+  gint                alpha_pix        = ALPHA;
+  gboolean            dither_alpha     = quantobj->want_dither_alpha;
+  gint                offsetx, offsety;
+  guint64            *index_used_count = quantobj->index_used_count;
+  gint64              total_size       = 0;
+  gint64              layer_size;
+  gint                count            = 0;
+
+  gimp_item_get_offset (GIMP_ITEM (layer), &offsetx, &offsety);
+
+  src_format  = gimp_drawable_get_format (GIMP_DRAWABLE (layer));
+  dest_format = gegl_buffer_get_format (new_buffer);
+
+  src_bpp  = babl_format_get_bytes_per_pixel (src_format);
+  dest_bpp = babl_format_get_bytes_per_pixel (dest_format);
+
+  has_alpha = babl_format_has_alpha (src_format);
+
+  /*  In the case of web/mono palettes, we actually force
+   *   grayscale drawables through the rgb pass2 functions
+   */
+  if (gimp_drawable_is_gray (GIMP_DRAWABLE (layer)))
+    {
+      red_pix = green_pix = blue_pix = GRAY;
+      alpha_pix = ALPHA_G;
+    }
+
+  iter = gegl_buffer_iterator_new (gimp_drawable_get_buffer (GIMP_DRAWABLE (layer)),
+                                   NULL, 0, NULL,
+                                   GEGL_ACCESS_READ, GEGL_ABYSS_NONE, 2);
+  src_roi = &iter->items[0].roi;
+
+  gegl_buffer_iterator_add (iter, new_buffer,
+                            NULL, 0, NULL,
+                            GEGL_ACCESS_WRITE, GEGL_ABYSS_NONE);
+
+  layer_size = (gimp_item_get_width  (GIMP_ITEM (layer)) *
+                gimp_item_get_height (GIMP_ITEM (layer)));
+
+  while (gegl_buffer_iterator_next (iter))
+    {
+      const guchar *src  = iter->items[0].data;
+      guchar       *dest = iter->items[1].data;
+      gint          row;
+
+      total_size += src_roi->height * src_roi->width;
+
+      for (row = 0; row < src_roi->height; row++)
+        {
+          gint col;
+
+          for (col = 0; col < src_roi->width; col++)
+            {
+              if (has_alpha)
+                {
+                  gboolean transparent = FALSE;
+
+                  if (dither_alpha)
+                    {
+                      gint dither_x = (col + offsetx + src_roi->x) & DM_WIDTHMASK;
+                      gint dither_y = (row + offsety + src_roi->y) & DM_HEIGHTMASK;
+
+                      if ((src[alpha_pix]) < DM[dither_x][dither_y])
+                        transparent = TRUE;
+                    }
+                  else
+                    {
+                      if (src[alpha_pix] <= 127)
+                        transparent = TRUE;
+                    }
+
+                  if (transparent)
+                    {
+                      dest[ALPHA_I] = 0;
+                      goto next_pixel;
+                    }
+                  else
+                    {
+                      dest[ALPHA_I] = 255;
+                    }
+                }
+
+              /* get pixel value and index into the cache */
+              rgb_to_lin (src[red_pix], src[green_pix], src[blue_pix],
+                          &R, &G, &B);
+
+              cachep = HIST_LIN (histogram, R, G, B);
+              /* If we have not seen this color before, find nearest
+               * colormap entry and update the cache
+               */
+              if (*cachep == 0)
+                fill_inverse_cmap_rgb (quantobj, histogram, R, G, B);
+
+              /* Now emit the colormap index for this cell, barfbarf */
+              index_used_count[dest[INDEXED] = *cachep - 1]++;
+
+            next_pixel:
+
+              src  += src_bpp;
+              dest += dest_bpp;
+            }
+        }
+
+      if (quantobj->progress && (count % 16 == 0))
+         gimp_progress_set_value (quantobj->progress,
+                                  (gdouble) total_size / (gdouble) layer_size);
+    }
+}
+
+static void
+median_cut_pass2_fixed_dither_rgb (QuantizeObj *quantobj,
+                                   GimpLayer   *layer,
+                                   GeglBuffer  *new_buffer)
+{
+  GeglBufferIterator *iter;
+  CFHistogram         histogram = quantobj->histogram;
+  ColorFreq          *cachep;
+  const Babl         *src_format;
+  const Babl         *dest_format;
+  GeglRectangle      *src_roi;
+  gint                src_bpp;
+  gint                dest_bpp;
+  gint                has_alpha;
+  gint                pixval1 = 0;
+  gint                pixval2 = 0;
+  Color              *color1;
+  Color              *color2;
+  gint                R, G, B;
+  gint                err1;
+  gint                err2;
+  gint                red_pix          = RED;
+  gint                green_pix        = GREEN;
+  gint                blue_pix         = BLUE;
+  gint                alpha_pix        = ALPHA;
+  gboolean            dither_alpha     = quantobj->want_dither_alpha;
+  gint                offsetx, offsety;
+  guint64            *index_used_count = quantobj->index_used_count;
+  gint64              total_size       = 0;
+  gint64              layer_size;
+  gint                count            = 0;
+
+  gimp_item_get_offset (GIMP_ITEM (layer), &offsetx, &offsety);
+
+  src_format  = gimp_drawable_get_format (GIMP_DRAWABLE (layer));
+  dest_format = gegl_buffer_get_format (new_buffer);
+
+  src_bpp  = babl_format_get_bytes_per_pixel (src_format);
+  dest_bpp = babl_format_get_bytes_per_pixel (dest_format);
+
+  has_alpha = babl_format_has_alpha (src_format);
+
+  /*  In the case of web/mono palettes, we actually force
+   *   grayscale drawables through the rgb pass2 functions
+   */
+  if (gimp_drawable_is_gray (GIMP_DRAWABLE (layer)))
+    {
+      red_pix = green_pix = blue_pix = GRAY;
+      alpha_pix = ALPHA_G;
+    }
+
+  iter = gegl_buffer_iterator_new (gimp_drawable_get_buffer (GIMP_DRAWABLE (layer)),
+                                   NULL, 0, NULL,
+                                   GEGL_ACCESS_READ, GEGL_ABYSS_NONE, 2);
+  src_roi = &iter->items[0].roi;
+
+  gegl_buffer_iterator_add (iter, new_buffer,
+                            NULL, 0, NULL,
+                            GEGL_ACCESS_WRITE, GEGL_ABYSS_NONE);
+
+  layer_size = (gimp_item_get_width  (GIMP_ITEM (layer)) *
+                gimp_item_get_height (GIMP_ITEM (layer)));
+
+  while (gegl_buffer_iterator_next (iter))
+    {
+      const guchar *src  = iter->items[0].data;
+      guchar       *dest = iter->items[1].data;
+      gint          row;
+
+      total_size += src_roi->height * src_roi->width;
+
+      for (row = 0; row < src_roi->height; row++)
+        {
+          gint col;
+
+          for (col = 0; col < src_roi->width; col++)
+            {
+              const int dmval =
+                DM[(col + offsetx + src_roi->x) & DM_WIDTHMASK]
+                [(row + offsety + src_roi->y) & DM_HEIGHTMASK];
+
+              if (has_alpha)
+                {
+                  gboolean transparent = FALSE;
+
+                  if (dither_alpha)
+                    {
+                      if (src[alpha_pix] < dmval)
+                        transparent = TRUE;
+                    }
+                  else
+                    {
+                      if (src[alpha_pix] <= 127)
+                        transparent = TRUE;
+                    }
+
+                  if (transparent)
+                    {
+                      dest[ALPHA_I] = 0;
+                      goto next_pixel;
+                    }
+                  else
+                    {
+                      dest[ALPHA_I] = 255;
+                    }
+                }
+
+              /* get pixel value and index into the cache */
+              rgb_to_lin (src[red_pix], src[green_pix], src[blue_pix],
+                          &R, &G, &B);
+
+              cachep = HIST_LIN (histogram, R, G, B);
+              /* If we have not seen this color before, find nearest
+               * colormap entry and update the cache
+               */
+              if (*cachep == 0)
+                fill_inverse_cmap_rgb (quantobj, histogram, R, G, B);
+
+              /* We now try to find a color which, when mixed in some
+               * fashion with the closest match, yields something
+               * closer to the desired color.  We do this by
+               * repeatedly extrapolating the color vector from one to
+               * the other until we find another color cell.  Then we
+               * assess the distance of both mixer colors from the
+               * intended color to determine their relative
+               * probabilities of being chosen.
+               */
+              pixval1 = *cachep - 1;
+              color1 = &quantobj->cmap[pixval1];
+
+              if (quantobj->actual_number_of_colors > 2)
+                {
+                  const gint re = src[red_pix]   - (gint) color1->red;
+                  const gint ge = src[green_pix] - (gint) color1->green;
+                  const gint be = src[blue_pix]  - (gint) color1->blue;
+                  gint       RV = src[red_pix]   + re;
+                  gint       GV = src[green_pix] + ge;
+                  gint       BV = src[blue_pix]  + be;
+
+                  do
+                    {
+                      rgb_to_lin ((CLAMP0255(RV)),
+                                  (CLAMP0255(GV)),
+                                  (CLAMP0255(BV)),
+                                  &R, &G, &B);
+
+                      cachep = HIST_LIN (histogram, R, G, B);
+                      /* If we have not seen this color before, find
+                       * nearest colormap entry and update the cache
+                       */
+                      if (*cachep == 0)
+                        fill_inverse_cmap_rgb (quantobj, histogram, R, G, B);
+
+                      pixval2 = *cachep - 1;
+                      RV += re;  GV += ge;  BV += be;
+                    }
+                  while ((pixval1 == pixval2) &&
+                         (!( (RV>255 || RV<0) || (GV>255 || GV<0) || (BV>255 || BV<0) )) &&
+                         (re || ge || be));
+                }
+
+              if (quantobj->actual_number_of_colors <= 2
+                  /* || pixval1 == pixval2 */) {
+                /* not enough colors to bother looking for an 'alternative'
+                   color (we may fail to do so anyway), so decide that
+                   the alternative color is simply the other cmap entry. */
+                pixval2 = (pixval1 + 1) %
+                  (quantobj->actual_number_of_colors);
+              }
+
+              /* always deterministically sort pixval1 and pixval2, to
+                 avoid artifacts in the dither range due to inverting our
+                 relative color viewpoint -- most obvious in 1-bit dither. */
+              if (pixval1 > pixval2)
+                {
+                  gint tmpval = pixval1;
+                  pixval1 = pixval2;
+                  pixval2 = tmpval;
+                  color1 = &quantobj->cmap[pixval1];
+                }
+
+              color2 = &quantobj->cmap[pixval2];
+
+              /* now figure out the relative probabilites of choosing
+                 either of our candidates. */
+#define DISTP(R1,G1,B1,R2,G2,B2,D) do {D = sqrt( 30*SQR((R1)-(R2)) + \
+                                                 59*SQR((G1)-(G2)) + \
+                                                 11*SQR((B1)-(B2)) ); }while(0)
+#define LIN_DISTP(R1,G1,B1,R2,G2,B2,D) do { \
+                int spacer1, spaceg1, spaceb1; \
+                int spacer2, spaceg2, spaceb2; \
+                rgb_to_unshifted_lin (R1,G1,B1, &spacer1, &spaceg1, &spaceb1); \
+                rgb_to_unshifted_lin (R2,G2,B2, &spacer2, &spaceg2, &spaceb2); \
+                D = sqrt(R_SCALE * SQR((spacer1)-(spacer2)) +           \
+                         G_SCALE * SQR((spaceg1)-(spaceg2)) + \
+                         B_SCALE * SQR((spaceb1)-(spaceb2))); \
+              } while(0)
+
+              /* although LIN_DISTP is more correct, DISTP is much faster and
+                 barely distinguishable. */
+              DISTP (color1->red, color1->green, color1->blue,
+                     src[red_pix], src[green_pix], src[blue_pix],
+                     err1);
+              DISTP (color2->red, color2->green, color2->blue,
+                     src[red_pix], src[green_pix], src[blue_pix],
+                     err2);
+
+              if (err1 || err2)
+                {
+                  const int proportion2 = (255 * err2) / (err1 + err2);
+                  if (dmval > proportion2)
+                    {
+                      pixval1 = pixval2; /* use color2 instead of color1*/
+                    }
+                }
+
+              /* Now emit the colormap index for this cell, barfbarf */
+              index_used_count[dest[INDEXED] = pixval1]++;
+
+            next_pixel:
+
+              src  += src_bpp;
+              dest += dest_bpp;
+            }
+        }
+
+      if (quantobj->progress && (count % 16 == 0))
+        gimp_progress_set_value (quantobj->progress,
+                                 (gdouble) total_size / (gdouble) layer_size);
+    }
+}
+
+static void
+median_cut_pass2_nodestruct_dither_rgb (QuantizeObj *quantobj,
+                                        GimpLayer   *layer,
+                                        GeglBuffer  *new_buffer)
+{
+  GeglBufferIterator *iter;
+  const Babl         *src_format;
+  const Babl         *dest_format;
+  GeglRectangle      *src_roi;
+  gint                src_bpp;
+  gint                dest_bpp;
+  gint                has_alpha;
+  gboolean            dither_alpha = quantobj->want_dither_alpha;
+  gint                red_pix      = RED;
+  gint                green_pix    = GREEN;
+  gint                blue_pix     = BLUE;
+  gint                alpha_pix    = ALPHA;
+  gint                lastindex    = 0;
+  gint                lastred      = -1;
+  gint                lastgreen    = -1;
+  gint                lastblue     = -1;
+  gint                offsetx, offsety;
+
+  gimp_item_get_offset (GIMP_ITEM (layer), &offsetx, &offsety);
+
+  src_format  = gimp_drawable_get_format (GIMP_DRAWABLE (layer));
+  dest_format = gegl_buffer_get_format (new_buffer);
+
+  src_bpp  = babl_format_get_bytes_per_pixel (src_format);
+  dest_bpp = babl_format_get_bytes_per_pixel (dest_format);
+
+  has_alpha = babl_format_has_alpha (src_format);
+
+  iter = gegl_buffer_iterator_new (gimp_drawable_get_buffer (GIMP_DRAWABLE (layer)),
+                                   NULL, 0, NULL,
+                                   GEGL_ACCESS_READ, GEGL_ABYSS_NONE, 2);
+  src_roi = &iter->items[0].roi;
+
+  gegl_buffer_iterator_add (iter, new_buffer,
+                            NULL, 0, NULL,
+                            GEGL_ACCESS_WRITE, GEGL_ABYSS_NONE);
+
+  while (gegl_buffer_iterator_next (iter))
+    {
+      const guchar *src  = iter->items[0].data;
+      guchar       *dest = iter->items[1].data;
+      gint          row;
+
+      for (row = 0; row < src_roi->height; row++)
+        {
+          gint col;
+
+          for (col = 0; col < src_roi->width; col++)
+            {
+              gboolean transparent = FALSE;
+
+              if (has_alpha)
+                {
+                  if (dither_alpha)
+                    {
+                      gint dither_x = (col + src_roi->x + offsetx) & DM_WIDTHMASK;
+                      gint dither_y = (row + src_roi->y + offsety) & DM_HEIGHTMASK;
+
+                      if ((src[alpha_pix]) < DM[dither_x][dither_y])
+                        transparent = TRUE;
+                    }
+                  else
+                    {
+                      if (src[alpha_pix] < 128)
+                        transparent = TRUE;
+                    }
+                }
+
+              if (! transparent)
+                {
+                  if ((lastred   == src[red_pix]) &&
+                      (lastgreen == src[green_pix]) &&
+                      (lastblue  == src[blue_pix]))
+                    {
+                      /*  same pixel color as last time  */
+                      dest[INDEXED] = lastindex;
+                      if (has_alpha)
+                        dest[ALPHA_I] = 255;
+                    }
+                  else
+                    {
+                      gint i;
+
+                      for (i = 0 ;
+                           i < quantobj->actual_number_of_colors;
+                           i++)
+                        {
+                          if ((quantobj->cmap[i].green == src[green_pix]) &&
+                              (quantobj->cmap[i].red   == src[red_pix]) &&
+                              (quantobj->cmap[i].blue  == src[blue_pix]))
+                          {
+                            lastred   = src[red_pix];
+                            lastgreen = src[green_pix];
+                            lastblue  = src[blue_pix];
+                            lastindex = i;
+
+                            goto got_color;
+                          }
+                        }
+                      g_error ("Non-existant color was expected to "
+                               "be in non-destructive colormap.");
+                    got_color:
+                      dest[INDEXED] = lastindex;
+                      if (has_alpha)
+                        dest[ALPHA_I] = 255;
+                    }
+                }
+              else
+                { /*  have alpha, and transparent  */
+                  dest[ALPHA_I] = 0;
+                }
+
+              src  += src_bpp;
+              dest += dest_bpp;
+            }
+        }
+    }
+}
+
+
+/*
+ * Initialize the error-limiting transfer function (lookup table).
+ * The raw F-S error computation can potentially compute error values of up to
+ * +- MAXJSAMPLE.  But we want the maximum correction applied to a pixel to be
+ * much less, otherwise obviously wrong pixels will be created.  (Typical
+ * effects include weird fringes at color-area boundaries, isolated bright
+ * pixels in a dark area, etc.)  The standard advice for avoiding this problem
+ * is to ensure that the "corners" of the color cube are allocated as output
+ * colors; then repeated errors in the same direction cannot cause cascading
+ * error buildup.  However, that only prevents the error from getting
+ * completely out of hand; Aaron Giles reports that error limiting improves
+ * the results even with corner colors allocated.
+ * A simple clamping of the error values to about +- MAXJSAMPLE/8 works pretty
+ * well, but the smoother transfer function used below is even better.  Thanks
+ * to Aaron Giles for this idea.
+ */
+
+static gint *
+init_error_limit (const int error_freedom)
+/* Allocate and fill in the error_limiter table */
+{
+  gint *table;
+  gint  inp, out;
+
+  /* #define STEPSIZE 16 */
+  /* #define STEPSIZE 200 */
+
+  table = g_new (gint, 255 * 2 + 1);
+  table += 255;                 /* so we can index -255 ... +255 */
+
+  if (error_freedom == 0)
+    {
+      /* Coarse function, much bleeding. */
+
+      const gint STEPSIZE = 190;
+
+      for (inp = 0; inp < STEPSIZE; inp++)
+        {
+          table[inp] = inp;
+          table[-inp] = -inp;
+        }
+
+      for (; inp <= 255; inp++)
+        {
+          table[inp] = STEPSIZE;
+          table[-inp] = -STEPSIZE;
+        }
+
+      return (table);
+    }
+  else
+    {
+      /* Smooth function, bleeding more constrained */
+
+      const gint STEPSIZE = 24;
+
+      /* Map errors 1:1 up to +- STEPSIZE */
+      out = 0;
+      for (inp = 0; inp < STEPSIZE; inp++, out++)
+        {
+          table[inp] = out;
+          table[-inp] = -out;
+        }
+
+      /* Map errors 1:2 up to +- 3*STEPSIZE */
+      for (; inp < STEPSIZE*3; inp++, out += (inp&1) ? 0 : 1)
+        {
+          table[inp] = out;
+          table[-inp] = -out;
+        }
+
+      /* Clamp the rest to final out value (which is STEPSIZE*2) */
+      for (; inp <= 255; inp++)
+        {
+          table[inp] = out;
+          table[-inp] = -out;
+        }
+
+      return table;
+    }
+}
+
+
+/*
+ * Map some rows of pixels to the output colormapped representation.
+ * Perform floyd-steinberg dithering.
+ */
+
+static void
+median_cut_pass2_fs_dither_gray (QuantizeObj *quantobj,
+                                 GimpLayer   *layer,
+                                 GeglBuffer  *new_buffer)
+{
+  GeglBuffer   *src_buffer;
+  CFHistogram   histogram = quantobj->histogram;
+  ColorFreq    *cachep;
+  Color        *color;
+  gint         *error_limiter;
+  const gshort *fs_err1, *fs_err2;
+  const gshort *fs_err3, *fs_err4;
+  const guchar *range_limiter;
+  const Babl   *src_format;
+  const Babl   *dest_format;
+  gint          src_bpp;
+  gint          dest_bpp;
+  guchar       *src_buf, *dest_buf;
+  gint         *next_row, *prev_row;
+  gint         *nr, *pr;
+  gint         *tmp;
+  gint          pixel;
+  gint          pixele;
+  gint          row, col;
+  gint          index;
+  gint          step_dest, step_src;
+  gint          odd_row;
+  gboolean      has_alpha;
+  gint          offsetx, offsety;
+  gboolean      dither_alpha = quantobj->want_dither_alpha;
+  gint          width, height;
+  guint64      *index_used_count = quantobj->index_used_count;
+
+  src_buffer = gimp_drawable_get_buffer (GIMP_DRAWABLE (layer));
+
+  gimp_item_get_offset (GIMP_ITEM (layer), &offsetx, &offsety);
+
+  src_format  = gimp_drawable_get_format (GIMP_DRAWABLE (layer));
+  dest_format = gegl_buffer_get_format (new_buffer);
+
+  src_bpp  = babl_format_get_bytes_per_pixel (src_format);
+  dest_bpp = babl_format_get_bytes_per_pixel (dest_format);
+
+  has_alpha = babl_format_has_alpha (src_format);
+
+  width  = gimp_item_get_width  (GIMP_ITEM (layer));
+  height = gimp_item_get_height (GIMP_ITEM (layer));
+
+  error_limiter = init_error_limit (quantobj->error_freedom);
+  range_limiter = range_array + 256;
+
+  src_buf  = g_malloc (width * src_bpp);
+  dest_buf = g_malloc (width * dest_bpp);
+
+  next_row = g_new (gint, width + 2);
+  prev_row = g_new0 (gint, width + 2);
+
+  fs_err1 = floyd_steinberg_error1 + 511;
+  fs_err2 = floyd_steinberg_error2 + 511;
+  fs_err3 = floyd_steinberg_error3 + 511;
+  fs_err4 = floyd_steinberg_error4 + 511;
+
+  odd_row = 0;
+
+  for (row = 0; row < height; row++)
+    {
+      const guchar *src;
+      guchar       *dest;
+
+      gegl_buffer_get (src_buffer, GEGL_RECTANGLE (0, row, width, 1),
+                       1.0, NULL, src_buf,
+                       GEGL_AUTO_ROWSTRIDE, GEGL_ABYSS_NONE);
+
+      src  = src_buf;
+      dest = dest_buf;
+
+      nr = next_row;
+      pr = prev_row + 1;
+
+      if (odd_row)
+        {
+          step_dest = -dest_bpp;
+          step_src  = -src_bpp;
+
+          src  += (width * src_bpp) - src_bpp;
+          dest += (width * dest_bpp) - dest_bpp;
+
+          nr += width + 1;
+          pr += width;
+
+          *(nr - 1) = 0;
+        }
+      else
+        {
+          step_dest = dest_bpp;
+          step_src  = src_bpp;
+
+          *(nr + 1) = 0;
+        }
+
+      *nr = 0;
+
+      for (col = 0; col < width; col++)
+        {
+          pixel = range_limiter[src[GRAY] + error_limiter[*pr]];
+
+          cachep = &histogram[pixel];
+          /* If we have not seen this color before, find nearest
+           * colormap entry and update the cache
+           */
+          if (*cachep == 0)
+            fill_inverse_cmap_gray (quantobj, histogram, pixel);
+
+          if (has_alpha)
+            {
+              gboolean transparent = FALSE;
+
+              if (odd_row)
+                {
+                  if (dither_alpha)
+                    {
+                      gint dither_x = ((width-col)+offsetx-1) & DM_WIDTHMASK;
+                      gint dither_y = (row+offsety) & DM_HEIGHTMASK;
+
+                      if ((src[ALPHA_G]) < DM[dither_x][dither_y])
+                        transparent = TRUE;
+                    }
+                  else
+                    {
+                      if (src[ALPHA_G] <= 127)
+                        transparent = TRUE;
+                    }
+
+                  if (transparent)
+                    {
+                      dest[ALPHA_I] = 0;
+                      pr--;
+                      nr--;
+                      *(nr - 1) = 0;
+                      goto next_pixel;
+                    }
+                  else
+                    {
+                      dest[ALPHA_I] = 255;
+                    }
+                }
+              else
+                {
+                  if (dither_alpha)
+                    {
+                      gint dither_x = (col + offsetx) & DM_WIDTHMASK;
+                      gint dither_y = (row + offsety) & DM_HEIGHTMASK;
+
+                      if ((src[ALPHA_G]) < DM[dither_x][dither_y])
+                        transparent = TRUE;
+                    }
+                  else
+                    {
+                      if (src[ALPHA_G] <= 127)
+                        transparent = TRUE;
+                    }
+
+                  if (transparent)
+                    {
+                      dest[ALPHA_I] = 0;
+                      pr++;
+                      nr++;
+                      *(nr + 1) = 0;
+                      goto next_pixel;
+                    }
+                  else
+                    {
+                      dest[ALPHA_I] = 255;
+                    }
+                }
+            }
+
+          index = *cachep - 1;
+          index_used_count[dest[INDEXED] = index]++;
+
+          color = &quantobj->cmap[index];
+          pixele = pixel - color->red;
+
+          if (odd_row)
+            {
+              *(--pr) += fs_err1[pixele];
+              *nr-- += fs_err2[pixele];
+              *nr += fs_err3[pixele];
+              *(nr-1) = fs_err4[pixele];
+            }
+          else
+            {
+              *(++pr) += fs_err1[pixele];
+              *nr++ += fs_err2[pixele];
+              *nr += fs_err3[pixele];
+              *(nr+1) = fs_err4[pixele];
+            }
+
+        next_pixel:
+
+          dest += step_dest;
+          src += step_src;
+        }
+
+      tmp = next_row;
+      next_row = prev_row;
+      prev_row = tmp;
+
+      odd_row = !odd_row;
+
+      gegl_buffer_set (new_buffer, GEGL_RECTANGLE (0, row, width, 1),
+                       0, NULL, dest_buf,
+                       GEGL_AUTO_ROWSTRIDE);
+    }
+
+  g_free (error_limiter - 255); /* good lord. */
+  g_free (next_row);
+  g_free (prev_row);
+  g_free (src_buf);
+  g_free (dest_buf);
+}
+
+static void
+median_cut_pass2_rgb_init (QuantizeObj *quantobj)
+{
+  int i;
+
+  zero_histogram_rgb (quantobj->histogram);
+
+  /* Mark all indices as currently unused */
+  memset (quantobj->index_used_count, 0, 256 * sizeof (guint64));
+
+  /* Make a version of our discovered colormap in linear space */
+  for (i = 0; i < quantobj->actual_number_of_colors; i++)
+    {
+      rgb_to_unshifted_lin (quantobj->cmap[i].red,
+                            quantobj->cmap[i].green,
+                            quantobj->cmap[i].blue,
+                            &quantobj->clin[i].red,
+                            &quantobj->clin[i].green,
+                            &quantobj->clin[i].blue);
+    }
+}
+
+static void
+median_cut_pass2_gray_init (QuantizeObj *quantobj)
+{
+  zero_histogram_gray (quantobj->histogram);
+
+  /* Mark all indices as currently unused */
+  memset (quantobj->index_used_count, 0, 256 * sizeof (guint64));
+}
+
+static void
+median_cut_pass2_fs_dither_rgb (QuantizeObj *quantobj,
+                                GimpLayer   *layer,
+                                GeglBuffer  *new_buffer)
+{
+  GeglBuffer   *src_buffer;
+  CFHistogram   histogram = quantobj->histogram;
+  ColorFreq    *cachep;
+  Color        *color;
+  gint         *error_limiter;
+  const gshort *fs_err1, *fs_err2;
+  const gshort *fs_err3, *fs_err4;
+  const guchar *range_limiter;
+  const Babl   *src_format;
+  const Babl   *dest_format;
+  gint          src_bpp;
+  gint          dest_bpp;
+  guchar       *src_buf, *dest_buf;
+  gint         *red_n_row, *red_p_row;
+  gint         *grn_n_row, *grn_p_row;
+  gint         *blu_n_row, *blu_p_row;
+  gint         *rnr, *rpr;
+  gint         *gnr, *gpr;
+  gint         *bnr, *bpr;
+  gint         *tmp;
+  gint          re, ge, be;
+  gint          row, col;
+  gint          index;
+  gint          step_dest, step_src;
+  gint          odd_row;
+  gboolean      has_alpha;
+  gint          width, height;
+  gint          red_pix   = RED;
+  gint          green_pix = GREEN;
+  gint          blue_pix  = BLUE;
+  gint          alpha_pix = ALPHA;
+  gint          offsetx, offsety;
+  gboolean      dither_alpha     = quantobj->want_dither_alpha;
+  guint64      *index_used_count = quantobj->index_used_count;
+  gint          global_rmax = 0, global_rmin = G_MAXINT;
+  gint          global_gmax = 0, global_gmin = G_MAXINT;
+  gint          global_bmax = 0, global_bmin = G_MAXINT;
+
+  src_buffer = gimp_drawable_get_buffer (GIMP_DRAWABLE (layer));
+
+  gimp_item_get_offset (GIMP_ITEM (layer), &offsetx, &offsety);
+
+  /*  In the case of web/mono palettes, we actually force
+   *   grayscale drawables through the rgb pass2 functions
+   */
+  if (gimp_drawable_is_gray (GIMP_DRAWABLE (layer)))
+    red_pix = green_pix = blue_pix = GRAY;
+
+  src_format  = gimp_drawable_get_format (GIMP_DRAWABLE (layer));
+  dest_format = gegl_buffer_get_format (new_buffer);
+
+  src_bpp  = babl_format_get_bytes_per_pixel (src_format);
+  dest_bpp = babl_format_get_bytes_per_pixel (dest_format);
+
+  has_alpha = babl_format_has_alpha (src_format);
+
+  width  = gimp_item_get_width  (GIMP_ITEM (layer));
+  height = gimp_item_get_height (GIMP_ITEM (layer));
+
+  error_limiter = init_error_limit (quantobj->error_freedom);
+  range_limiter = range_array + 256;
+
+  /* find the bounding box of the palette colors --
+     we use this for hard-clamping our error-corrected
+     values so that we can't continuously accelerate outside
+     of our attainable gamut, which looks icky. */
+  for (index = 0; index < quantobj->actual_number_of_colors; index++)
+    {
+      global_rmax = MAX(global_rmax, quantobj->clin[index].red);
+      global_rmin = MIN(global_rmin, quantobj->clin[index].red);
+      global_gmax = MAX(global_gmax, quantobj->clin[index].green);
+      global_gmin = MIN(global_gmin, quantobj->clin[index].green);
+      global_bmax = MAX(global_bmax, quantobj->clin[index].blue);
+      global_bmin = MIN(global_bmin, quantobj->clin[index].blue);
+    }
+
+  src_buf  = g_malloc (width * src_bpp);
+  dest_buf = g_malloc (width * dest_bpp);
+
+  red_n_row = g_new (gint, width + 2);
+  red_p_row = g_new0 (gint, width + 2);
+  grn_n_row = g_new (gint, width + 2);
+  grn_p_row = g_new0 (gint, width + 2);
+  blu_n_row = g_new (gint, width + 2);
+  blu_p_row = g_new0 (gint, width + 2);
+
+  fs_err1 = floyd_steinberg_error1 + 511;
+  fs_err2 = floyd_steinberg_error2 + 511;
+  fs_err3 = floyd_steinberg_error3 + 511;
+  fs_err4 = floyd_steinberg_error4 + 511;
+
+  odd_row = 0;
+
+  for (row = 0; row < height; row++)
+    {
+      const guchar *src;
+      guchar       *dest;
+
+      gegl_buffer_get (src_buffer, GEGL_RECTANGLE (0, row, width, 1),
+                       1.0, NULL, src_buf,
+                       GEGL_AUTO_ROWSTRIDE, GEGL_ABYSS_NONE);
+
+      src  = src_buf;
+      dest = dest_buf;
+
+      rnr = red_n_row;
+      gnr = grn_n_row;
+      bnr = blu_n_row;
+      rpr = red_p_row + 1;
+      gpr = grn_p_row + 1;
+      bpr = blu_p_row + 1;
+
+      if (odd_row)
+        {
+          step_dest = -dest_bpp;
+          step_src  = -src_bpp;
+
+          src += (width * src_bpp) - src_bpp;
+          dest += (width * dest_bpp) - dest_bpp;
+
+          rnr += width + 1;
+          gnr += width + 1;
+          bnr += width + 1;
+          rpr += width;
+          gpr += width;
+          bpr += width;
+
+          *(rnr - 1) = *(gnr - 1) = *(bnr - 1) = 0;
+        }
+      else
+        {
+          step_dest = dest_bpp;
+          step_src  = src_bpp;
+
+          *(rnr + 1) = *(gnr + 1) = *(bnr + 1) = 0;
+        }
+
+      *rnr = *gnr = *bnr = 0;
+
+      for (col = 0; col < width; col++)
+        {
+          if (has_alpha)
+            {
+              gboolean transparent = FALSE;
+
+              if (odd_row)
+                {
+                  if (dither_alpha)
+                    {
+                      gint dither_x = ((width-col)+offsetx-1) & DM_WIDTHMASK;
+                      gint dither_y = (row+offsety) & DM_HEIGHTMASK;
+
+                      if ((src[alpha_pix]) < DM[dither_x][dither_y])
+                        transparent = TRUE;
+                    }
+                  else
+                    {
+                      if (src[alpha_pix] <= 127)
+                        transparent = TRUE;
+                    }
+
+                  if (transparent)
+                    {
+                      dest[ALPHA_I] = 0;
+                      rpr--; gpr--; bpr--;
+                      rnr--; gnr--; bnr--;
+                      *(rnr - 1) = *(gnr - 1) = *(bnr - 1) = 0;
+                      goto next_pixel;
+                    }
+                  else
+                    {
+                      dest[ALPHA_I] = 255;
+                    }
+                }
+              else
+                {
+                  if (dither_alpha)
+                    {
+                      gint dither_x = (col + offsetx) & DM_WIDTHMASK;
+                      gint dither_y = (row + offsety) & DM_HEIGHTMASK;
+
+                      if ((src[alpha_pix]) < DM[dither_x][dither_y])
+                        transparent = TRUE;
+                    }
+                  else
+                    {
+                      if (src[alpha_pix] <= 127)
+                        transparent = TRUE;
+                    }
+
+                  if (transparent)
+                    {
+                      dest[ALPHA_I] = 0;
+                      rpr++; gpr++; bpr++;
+                      rnr++; gnr++; bnr++;
+                      *(rnr + 1) = *(gnr + 1) = *(bnr + 1) = 0;
+                      goto next_pixel;
+                    }
+                  else
+                    {
+                      dest[ALPHA_I] = 255;
+                    }
+                }
+            }
+
+#if 0
+          /* hmm. */
+
+          r = range_limiter[src[red_pix] + error_limiter[*rpr]];
+          g = range_limiter[src[green_pix] + error_limiter[*gpr]];
+          b = range_limiter[src[blue_pix] + error_limiter[*bpr]];
+
+          re = r >> R_SHIFT;
+          ge = g >> G_SHIFT;
+          be = b >> B_SHIFT;
+
+          rgb_to_lin (r, g, b, &re, &ge, &be);
+#endif
+          rgb_to_unshifted_lin (src[red_pix], src[green_pix], src[blue_pix],
+                                &re, &ge, &be);
+
+          /*
+            re = CLAMP(re, global_rmin, global_rmax);
+            ge = CLAMP(ge, global_gmin, global_gmax);
+            be = CLAMP(be, global_bmin, global_bmax);*/
+
+          re = range_limiter[re + error_limiter[*rpr]];
+          ge = range_limiter[ge + error_limiter[*gpr]];
+          be = range_limiter[be + error_limiter[*bpr]];
+
+          cachep = HIST_LIN (histogram,
+                             RSDF (re),
+                             GSDF (ge),
+                             BSDF (be));
+          /* If we have not seen this color before, find nearest
+           * colormap entry and update the cache
+           */
+          if (*cachep == 0)
+            fill_inverse_cmap_rgb (quantobj, histogram,
+                                   RSDF (re),
+                                   GSDF (ge),
+                                   BSDF (be));
+
+          index = *cachep - 1;
+          index_used_count[index]++;
+          dest[INDEXED] = index;
+
+          /*if (re > global_rmax)
+            re = (re + 3*global_rmax) / 4;
+          else if (re < global_rmin)
+          re = (re + 3*global_rmin) / 4;*/
+
+          /* We constrain chroma error extra-hard so that it
+             doesn't run away and steal the thunder from the
+             lightness error where all the detail usually is. */
+          if (ge > global_gmax)
+            ge = (ge + 3*global_gmax) / 4;
+          else if (ge < global_gmin)
+            ge = (ge + 3*global_gmin) / 4;
+          if (be > global_bmax)
+            be = (be + 3*global_bmax) / 4;
+          else if (be < global_bmin)
+            be = (be + 3*global_bmin) / 4;
+
+          color = &quantobj->clin[index];
+
+#if 0
+          if ((re > 0 && re < 255) /* HMM &&
+              ge >= 0 && ge <= 255 &&
+              be >= 0 && be <= 255*/)
+            {
+              ge = ge - color->green;
+              be = be - color->blue;
+              re = re - color->red;
+            }
+          else
+            {
+              /* color pretty much undefined now; nullify error. */
+              re = ge = be = 0;
+            }
+#endif
+
+          if (re <= 0 || re >= 255)
+            re = ge = be = 0;
+          else
+            {
+              re = re - color->red;
+              ge = ge - color->green;
+              be = be - color->blue;
+            }
+
+          if (odd_row)
+            {
+              *(--rpr) += fs_err1[re];
+              *(--gpr) += fs_err1[ge];
+              *(--bpr) += fs_err1[be];
+
+              *rnr-- += fs_err2[re];
+              *gnr-- += fs_err2[ge];
+              *bnr-- += fs_err2[be];
+
+              *rnr += fs_err3[re];
+              *gnr += fs_err3[ge];
+              *bnr += fs_err3[be];
+
+              *(rnr-1) = fs_err4[re];
+              *(gnr-1) = fs_err4[ge];
+              *(bnr-1) = fs_err4[be];
+            }
+          else
+            {
+              *(++rpr) += fs_err1[re];
+              *(++gpr) += fs_err1[ge];
+              *(++bpr) += fs_err1[be];
+
+              *rnr++ += fs_err2[re];
+              *gnr++ += fs_err2[ge];
+              *bnr++ += fs_err2[be];
+
+              *rnr += fs_err3[re];
+              *gnr += fs_err3[ge];
+              *bnr += fs_err3[be];
+
+              *(rnr+1) = fs_err4[re];
+              *(gnr+1) = fs_err4[ge];
+              *(bnr+1) = fs_err4[be];
+            }
+
+        next_pixel:
+
+          dest += step_dest;
+          src += step_src;
+        }
+
+      tmp = red_n_row;
+      red_n_row = red_p_row;
+      red_p_row = tmp;
+
+      tmp = grn_n_row;
+      grn_n_row = grn_p_row;
+      grn_p_row = tmp;
+
+      tmp = blu_n_row;
+      blu_n_row = blu_p_row;
+      blu_p_row = tmp;
+
+      odd_row = !odd_row;
+
+      gegl_buffer_set (new_buffer, GEGL_RECTANGLE (0, row, width, 1),
+                       0, NULL, dest_buf,
+                       GEGL_AUTO_ROWSTRIDE);
+
+      if (quantobj->progress && (row % 16 == 0))
+        gimp_progress_set_value (quantobj->progress,
+                                 (gdouble) row / (gdouble) height);
+    }
+
+  g_free (error_limiter - 255);
+  g_free (red_n_row);
+  g_free (red_p_row);
+  g_free (grn_n_row);
+  g_free (grn_p_row);
+  g_free (blu_n_row);
+  g_free (blu_p_row);
+  g_free (src_buf);
+  g_free (dest_buf);
+}
+
+
+static void
+delete_median_cut (QuantizeObj *quantobj)
+{
+  g_free (quantobj->histogram);
+  g_free (quantobj);
+}
+
+
+void
+gimp_image_convert_indexed_set_dither_matrix (const guchar *matrix,
+                                              gint          width,
+                                              gint          height)
+{
+  gint x;
+  gint y;
+
+  /* if matrix is invalid, restore the default matrix */
+  if (matrix == NULL || width == 0 || height == 0)
+    {
+      matrix = (const guchar *) DM_ORIGINAL;
+      width  = DM_WIDTH;
+      height = DM_HEIGHT;
+    }
+
+  g_return_if_fail ((DM_WIDTH % width) == 0);
+  g_return_if_fail ((DM_HEIGHT % height) == 0);
+
+  for (y = 0; y < DM_HEIGHT; y++)
+    {
+      for (x = 0; x < DM_WIDTH; x++)
+        {
+          DM[x][y] = matrix[((x % width) * height) + (y % height)];
+        }
+    }
+}
+
+
+/**************************************************************/
+static QuantizeObj *
+initialize_median_cut (GimpImageBaseType       type,
+                       gint                    num_colors,
+                       GimpConvertDitherType   dither_type,
+                       GimpConvertPaletteType  palette_type,
+                       GimpPalette            *custom_palette,
+                       gboolean                want_dither_alpha,
+                       GimpProgress           *progress)
+{
+  QuantizeObj *quantobj;
+
+  /* Initialize the data structures */
+  quantobj = g_new (QuantizeObj, 1);
+
+  if (type == GIMP_GRAY && palette_type == GIMP_CONVERT_PALETTE_GENERATE)
+    quantobj->histogram = g_new (ColorFreq, 256);
+  else
+    quantobj->histogram = g_new (ColorFreq,
+                                 HIST_R_ELEMS * HIST_G_ELEMS * HIST_B_ELEMS);
+
+  quantobj->custom_palette           = custom_palette;
+  quantobj->desired_number_of_colors = num_colors;
+  quantobj->want_dither_alpha        = want_dither_alpha;
+  quantobj->progress                 = progress;
+
+  switch (type)
+    {
+    case GIMP_GRAY:
+      switch (palette_type)
+        {
+        case GIMP_CONVERT_PALETTE_GENERATE:
+          quantobj->first_pass = median_cut_pass1_gray;
+          break;
+        case GIMP_CONVERT_PALETTE_WEB:
+          quantobj->first_pass = webpal_pass1;
+          break;
+        case GIMP_CONVERT_PALETTE_CUSTOM:
+          quantobj->first_pass = custompal_pass1;
+          needs_quantize = TRUE;
+          break;
+        case GIMP_CONVERT_PALETTE_MONO:
+        default:
+          quantobj->first_pass = monopal_pass1;
+        }
+
+      if (palette_type == GIMP_CONVERT_PALETTE_WEB ||
+          palette_type == GIMP_CONVERT_PALETTE_CUSTOM)
+        {
+          switch (dither_type)
+            {
+            case GIMP_CONVERT_DITHER_NODESTRUCT:
+            default:
+              g_warning("Uh-oh, bad dither type, W1");
+            case GIMP_CONVERT_DITHER_NONE:
+              quantobj->second_pass_init = median_cut_pass2_rgb_init;
+              quantobj->second_pass = median_cut_pass2_no_dither_rgb;
+              break;
+            case GIMP_CONVERT_DITHER_FS:
+              quantobj->error_freedom = 0;
+              quantobj->second_pass_init = median_cut_pass2_rgb_init;
+              quantobj->second_pass = median_cut_pass2_fs_dither_rgb;
+              break;
+            case GIMP_CONVERT_DITHER_FS_LOWBLEED:
+              quantobj->error_freedom = 1;
+              quantobj->second_pass_init = median_cut_pass2_rgb_init;
+              quantobj->second_pass = median_cut_pass2_fs_dither_rgb;
+              break;
+            case GIMP_CONVERT_DITHER_FIXED:
+              quantobj->second_pass_init = median_cut_pass2_rgb_init;
+              quantobj->second_pass = median_cut_pass2_fixed_dither_rgb;
+              break;
+            }
+        }
+      else
+        {
+          switch (dither_type)
+            {
+            case GIMP_CONVERT_DITHER_NODESTRUCT:
+            default:
+              g_warning("Uh-oh, bad dither type, W2");
+            case GIMP_CONVERT_DITHER_NONE:
+              quantobj->second_pass_init = median_cut_pass2_gray_init;
+              quantobj->second_pass = median_cut_pass2_no_dither_gray;
+              break;
+            case GIMP_CONVERT_DITHER_FS:
+              quantobj->error_freedom = 0;
+              quantobj->second_pass_init = median_cut_pass2_gray_init;
+              quantobj->second_pass = median_cut_pass2_fs_dither_gray;
+              break;
+            case GIMP_CONVERT_DITHER_FS_LOWBLEED:
+              quantobj->error_freedom = 1;
+              quantobj->second_pass_init = median_cut_pass2_gray_init;
+              quantobj->second_pass = median_cut_pass2_fs_dither_gray;
+              break;
+            case GIMP_CONVERT_DITHER_FIXED:
+              quantobj->second_pass_init = median_cut_pass2_gray_init;
+              quantobj->second_pass = median_cut_pass2_fixed_dither_gray;
+              break;
+            }
+        }
+      break;
+
+    case GIMP_RGB:
+      switch (palette_type)
+        {
+        case GIMP_CONVERT_PALETTE_GENERATE:
+          quantobj->first_pass = median_cut_pass1_rgb;
+          break;
+        case GIMP_CONVERT_PALETTE_WEB:
+          quantobj->first_pass = webpal_pass1;
+          needs_quantize = TRUE;
+          break;
+        case GIMP_CONVERT_PALETTE_CUSTOM:
+          quantobj->first_pass = custompal_pass1;
+          needs_quantize = TRUE;
+          break;
+        case GIMP_CONVERT_PALETTE_MONO:
+        default:
+          quantobj->first_pass = monopal_pass1;
+        }
+
+      switch (dither_type)
+        {
+        case GIMP_CONVERT_DITHER_NONE:
+          quantobj->second_pass_init = median_cut_pass2_rgb_init;
+          quantobj->second_pass = median_cut_pass2_no_dither_rgb;
+          break;
+        case GIMP_CONVERT_DITHER_FS:
+          quantobj->error_freedom = 0;
+          quantobj->second_pass_init = median_cut_pass2_rgb_init;
+          quantobj->second_pass = median_cut_pass2_fs_dither_rgb;
+          break;
+        case GIMP_CONVERT_DITHER_FS_LOWBLEED:
+          quantobj->error_freedom = 1;
+          quantobj->second_pass_init = median_cut_pass2_rgb_init;
+          quantobj->second_pass = median_cut_pass2_fs_dither_rgb;
+          break;
+        case GIMP_CONVERT_DITHER_NODESTRUCT:
+          quantobj->second_pass_init = NULL;
+          quantobj->second_pass = median_cut_pass2_nodestruct_dither_rgb;
+          break;
+        case GIMP_CONVERT_DITHER_FIXED:
+          quantobj->second_pass_init = median_cut_pass2_rgb_init;
+          quantobj->second_pass = median_cut_pass2_fixed_dither_rgb;
+          break;
+        }
+      break;
+
+    default:
+      break;
+    }
+
+  quantobj->delete_func = delete_median_cut;
+
+  return quantobj;
+}
diff --git a/app/core/gimpimage-convert-indexed.h b/app/core/gimpimage-convert-indexed.h
new file mode 100644
index 0000000..ba51f02
--- /dev/null
+++ b/app/core/gimpimage-convert-indexed.h
@@ -0,0 +1,41 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_IMAGE_CONVERT_INDEXED_H__
+#define __GIMP_IMAGE_CONVERT_INDEXED_H__
+
+
+#define MAXNUMCOLORS 256
+
+
+gboolean   gimp_image_convert_indexed      (GimpImage               *image,
+                                            GimpConvertPaletteType   palette_type,
+                                            gint                     max_colors,
+                                            gboolean                 remove_duplicates,
+                                            GimpConvertDitherType    dither_type,
+                                            gboolean                 dither_alpha,
+                                            gboolean                 dither_text_layers,
+                                            GimpPalette             *custom_palette,
+                                            GimpProgress            *progress,
+                                            GError                 **error);
+
+void  gimp_image_convert_indexed_set_dither_matrix (const guchar *matrix,
+                                                    gint          width,
+                                                    gint          height);
+
+
+#endif  /*  __GIMP_IMAGE_CONVERT_INDEXED_H__  */
diff --git a/app/core/gimpimage-convert-precision.c b/app/core/gimpimage-convert-precision.c
new file mode 100644
index 0000000..71a613c
--- /dev/null
+++ b/app/core/gimpimage-convert-precision.c
@@ -0,0 +1,304 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpimage-convert-precision.c
+ * Copyright (C) 2012 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <cairo.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpcolor/gimpcolor.h"
+
+#include "core-types.h"
+
+#include "gegl/gimp-babl.h"
+#include "gegl/gimp-gegl-loops.h"
+
+#include "gimpchannel.h"
+#include "gimpdrawable.h"
+#include "gimpdrawable-operation.h"
+#include "gimpimage.h"
+#include "gimpimage-color-profile.h"
+#include "gimpimage-convert-precision.h"
+#include "gimpimage-undo.h"
+#include "gimpimage-undo-push.h"
+#include "gimpobjectqueue.h"
+#include "gimpprogress.h"
+
+#include "text/gimptextlayer.h"
+
+#include "gimp-intl.h"
+
+
+void
+gimp_image_convert_precision (GimpImage        *image,
+                              GimpPrecision     precision,
+                              GeglDitherMethod  layer_dither_type,
+                              GeglDitherMethod  text_layer_dither_type,
+                              GeglDitherMethod  mask_dither_type,
+                              GimpProgress     *progress)
+{
+  GimpColorProfile *old_profile;
+  GimpColorProfile *new_profile = NULL;
+  const Babl       *old_format;
+  const Babl       *new_format;
+  GimpObjectQueue  *queue;
+  GimpProgress     *sub_progress;
+  GList            *layers;
+  GimpDrawable     *drawable;
+  const gchar      *undo_desc    = NULL;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (precision != gimp_image_get_precision (image));
+  g_return_if_fail (gimp_babl_is_valid (gimp_image_get_base_type (image),
+                                        precision));
+  g_return_if_fail (progress == NULL || GIMP_IS_PROGRESS (progress));
+
+  switch (precision)
+    {
+    case GIMP_PRECISION_U8_LINEAR:
+      undo_desc = C_("undo-type", "Convert Image to 8 bit linear integer");
+      break;
+    case GIMP_PRECISION_U8_GAMMA:
+      undo_desc = C_("undo-type", "Convert Image to 8 bit gamma integer");
+      break;
+    case GIMP_PRECISION_U16_LINEAR:
+      undo_desc = C_("undo-type", "Convert Image to 16 bit linear integer");
+      break;
+    case GIMP_PRECISION_U16_GAMMA:
+      undo_desc = C_("undo-type", "Convert Image to 16 bit gamma integer");
+      break;
+    case GIMP_PRECISION_U32_LINEAR:
+      undo_desc = C_("undo-type", "Convert Image to 32 bit linear integer");
+      break;
+    case GIMP_PRECISION_U32_GAMMA:
+      undo_desc = C_("undo-type", "Convert Image to 32 bit gamma integer");
+      break;
+    case GIMP_PRECISION_HALF_LINEAR:
+      undo_desc = C_("undo-type", "Convert Image to 16 bit linear floating point");
+      break;
+    case GIMP_PRECISION_HALF_GAMMA:
+      undo_desc = C_("undo-type", "Convert Image to 16 bit gamma floating point");
+      break;
+    case GIMP_PRECISION_FLOAT_LINEAR:
+      undo_desc = C_("undo-type", "Convert Image to 32 bit linear floating point");
+      break;
+    case GIMP_PRECISION_FLOAT_GAMMA:
+      undo_desc = C_("undo-type", "Convert Image to 32 bit gamma floating point");
+      break;
+    case GIMP_PRECISION_DOUBLE_LINEAR:
+      undo_desc = C_("undo-type", "Convert Image to 64 bit linear floating point");
+      break;
+    case GIMP_PRECISION_DOUBLE_GAMMA:
+      undo_desc = C_("undo-type", "Convert Image to 64 bit gamma floating point");
+      break;
+    }
+
+  if (progress)
+    gimp_progress_start (progress, FALSE, "%s", undo_desc);
+
+  queue        = gimp_object_queue_new (progress);
+  sub_progress = GIMP_PROGRESS (queue);
+
+  layers = gimp_image_get_layer_list (image);
+  gimp_object_queue_push_list (queue, layers);
+  g_list_free (layers);
+
+  gimp_object_queue_push (queue, gimp_image_get_mask (image));
+  gimp_object_queue_push_container (queue, gimp_image_get_channels (image));
+
+  g_object_freeze_notify (G_OBJECT (image));
+
+  gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_IMAGE_CONVERT,
+                               undo_desc);
+
+  /*  Push the image precision to the stack  */
+  gimp_image_undo_push_image_precision (image, NULL);
+
+  old_profile = gimp_image_get_color_profile (image);
+  old_format  = gimp_image_get_layer_format (image, FALSE);
+
+  gimp_image_set_converting (image, TRUE);
+
+  /*  Set the new precision  */
+  g_object_set (image, "precision", precision, NULL);
+
+  new_format = gimp_image_get_layer_format (image, FALSE);
+
+  if (old_profile)
+    {
+      if (gimp_babl_format_get_linear (old_format) !=
+          gimp_babl_format_get_linear (new_format))
+        {
+          /* when converting between linear and gamma, we create a new
+           * profile using the original profile's chromacities and
+           * whitepoint, but a linear/sRGB-gamma TRC.
+           */
+
+          if (gimp_babl_format_get_linear (new_format))
+            {
+              new_profile =
+                gimp_color_profile_new_linear_from_color_profile (old_profile);
+            }
+          else
+            {
+              new_profile =
+                gimp_color_profile_new_srgb_trc_from_color_profile (old_profile);
+            }
+
+          /* if a new profile cannot be be generated, convert to the
+           * builtin profile, which is better than leaving the user with
+           * broken colors
+           */
+          if (! new_profile)
+            {
+              new_profile = gimp_image_get_builtin_color_profile (image);
+              g_object_ref (new_profile);
+            }
+        }
+
+      if (! new_profile)
+        new_profile = g_object_ref (old_profile);
+    }
+
+  while ((drawable = gimp_object_queue_pop (queue)))
+    {
+      if (drawable == GIMP_DRAWABLE (gimp_image_get_mask (image)))
+        {
+          GeglBuffer *buffer;
+
+          gimp_image_undo_push_mask_precision (image, NULL,
+                                               GIMP_CHANNEL (drawable));
+
+          buffer = gegl_buffer_new (GEGL_RECTANGLE (0, 0,
+                                                    gimp_image_get_width  (image),
+                                                    gimp_image_get_height (image)),
+                                    gimp_image_get_mask_format (image));
+
+          gimp_gegl_buffer_copy (gimp_drawable_get_buffer (drawable), NULL,
+                                 GEGL_ABYSS_NONE,
+                                 buffer, NULL);
+
+          gimp_drawable_set_buffer (drawable, FALSE, NULL, buffer);
+          g_object_unref (buffer);
+
+          gimp_progress_set_value (sub_progress, 1.0);
+        }
+      else
+        {
+          gint dither_type;
+
+          if (gimp_item_is_text_layer (GIMP_ITEM (drawable)))
+            dither_type = text_layer_dither_type;
+          else
+            dither_type = layer_dither_type;
+
+          gimp_drawable_convert_type (drawable, image,
+                                      gimp_drawable_get_base_type (drawable),
+                                      precision,
+                                      gimp_drawable_has_alpha (drawable),
+                                      new_profile,
+                                      dither_type,
+                                      mask_dither_type,
+                                      TRUE, sub_progress);
+        }
+    }
+
+  if (new_profile)
+    {
+      if (new_profile != old_profile)
+        gimp_image_set_color_profile (image, new_profile, NULL);
+
+      g_object_unref (new_profile);
+    }
+
+  gimp_image_set_converting (image, FALSE);
+
+  gimp_image_undo_group_end (image);
+
+  gimp_image_precision_changed (image);
+  g_object_thaw_notify (G_OBJECT (image));
+
+  g_object_unref (queue);
+
+  if (progress)
+    gimp_progress_end (progress);
+}
+
+void
+gimp_image_convert_dither_u8 (GimpImage    *image,
+                              GimpProgress *progress)
+{
+  GeglNode *dither;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (progress == NULL || GIMP_IS_PROGRESS (progress));
+
+  dither = gegl_node_new_child (NULL,
+                                "operation", "gegl:noise-rgb",
+                                "red",       1.0 / 256.0,
+                                "green",     1.0 / 256.0,
+                                "blue",      1.0 / 256.0,
+                                "linear",    FALSE,
+                                "gaussian",  FALSE,
+                                NULL);
+
+  if (dither)
+    {
+      GimpObjectQueue *queue;
+      GimpProgress    *sub_progress;
+      GList           *layers;
+      GList           *list;
+      GimpDrawable    *drawable;
+
+      if (progress)
+        gimp_progress_start (progress, FALSE, "%s", _("Dithering"));
+
+      queue        = gimp_object_queue_new (progress);
+      sub_progress = GIMP_PROGRESS (queue);
+
+      layers = gimp_image_get_layer_list (image);
+
+      for (list = layers; list; list = g_list_next (list))
+        {
+          if (! gimp_viewable_get_children (list->data) &&
+              ! gimp_item_is_text_layer (list->data))
+            {
+              gimp_object_queue_push (queue, list->data);
+            }
+        }
+
+      g_list_free (layers);
+
+      while ((drawable = gimp_object_queue_pop (queue)))
+        {
+          gimp_drawable_apply_operation (drawable, sub_progress,
+                                         _("Dithering"),
+                                         dither);
+        }
+
+      g_object_unref (queue);
+
+      if (progress)
+        gimp_progress_end (progress);
+
+      g_object_unref (dither);
+    }
+}
diff --git a/app/core/gimpimage-convert-precision.h b/app/core/gimpimage-convert-precision.h
new file mode 100644
index 0000000..cd3a010
--- /dev/null
+++ b/app/core/gimpimage-convert-precision.h
@@ -0,0 +1,36 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpimage-convert-precision.h
+ * Copyright (C) 2012 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_IMAGE_CONVERT_PRECISION_H__
+#define __GIMP_IMAGE_CONVERT_PRECISION_H__
+
+
+void   gimp_image_convert_precision (GimpImage        *image,
+                                     GimpPrecision     precision,
+                                     GeglDitherMethod  layer_dither_type,
+                                     GeglDitherMethod  text_layer_dither_type,
+                                     GeglDitherMethod  mask_dither_type,
+                                     GimpProgress     *progress);
+
+void   gimp_image_convert_dither_u8 (GimpImage        *image,
+                                     GimpProgress     *progress);
+
+
+#endif  /*  __GIMP_IMAGE_CONVERT_PRECISION_H__  */
diff --git a/app/core/gimpimage-convert-type.c b/app/core/gimpimage-convert-type.c
new file mode 100644
index 0000000..4298a49
--- /dev/null
+++ b/app/core/gimpimage-convert-type.c
@@ -0,0 +1,162 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <cairo.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpcolor/gimpcolor.h"
+
+#include "core-types.h"
+
+#include "gegl/gimp-babl.h"
+
+#include "gimp.h"
+#include "gimpdrawable.h"
+#include "gimpimage.h"
+#include "gimpimage-color-profile.h"
+#include "gimpimage-colormap.h"
+#include "gimpimage-convert-type.h"
+#include "gimpimage-undo.h"
+#include "gimpimage-undo-push.h"
+#include "gimpobjectqueue.h"
+#include "gimpprogress.h"
+
+#include "gimp-intl.h"
+
+
+gboolean
+gimp_image_convert_type (GimpImage          *image,
+                         GimpImageBaseType   new_type,
+                         GimpColorProfile   *dest_profile,
+                         GimpProgress       *progress,
+                         GError            **error)
+{
+  GimpImageBaseType  old_type;
+  const Babl        *new_layer_format;
+  GimpObjectQueue   *queue;
+  GList             *all_layers;
+  GimpDrawable      *drawable;
+  const gchar       *undo_desc = NULL;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+  g_return_val_if_fail (new_type != gimp_image_get_base_type (image), FALSE);
+  g_return_val_if_fail (new_type != GIMP_INDEXED, FALSE);
+  g_return_val_if_fail (gimp_babl_is_valid (new_type,
+                                            gimp_image_get_precision (image)),
+                        FALSE);
+  g_return_val_if_fail (dest_profile == NULL || GIMP_IS_COLOR_PROFILE (dest_profile),
+                        FALSE);
+  g_return_val_if_fail (progress == NULL || GIMP_IS_PROGRESS (progress), FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  new_layer_format = gimp_babl_format (new_type,
+                                       gimp_image_get_precision (image),
+                                       TRUE);
+
+  if (dest_profile &&
+      ! gimp_image_validate_color_profile_by_format (new_layer_format,
+                                                     dest_profile,
+                                                     NULL, error))
+    {
+      return FALSE;
+    }
+
+  switch (new_type)
+    {
+    case GIMP_RGB:
+      undo_desc = C_("undo-type", "Convert Image to RGB");
+      break;
+
+    case GIMP_GRAY:
+      undo_desc = C_("undo-type", "Convert Image to Grayscale");
+      break;
+
+    default:
+      g_return_val_if_reached (FALSE);
+    }
+
+  gimp_set_busy (image->gimp);
+
+  queue    = gimp_object_queue_new (progress);
+  progress = GIMP_PROGRESS (queue);
+
+  all_layers = gimp_image_get_layer_list (image);
+  gimp_object_queue_push_list (queue, all_layers);
+  g_list_free (all_layers);
+
+  g_object_freeze_notify (G_OBJECT (image));
+
+  gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_IMAGE_CONVERT,
+                               undo_desc);
+
+  /*  Push the image type to the stack  */
+  gimp_image_undo_push_image_type (image, NULL);
+
+  /*  Set the new base type  */
+  old_type = gimp_image_get_base_type (image);
+
+  g_object_set (image, "base-type", new_type, NULL);
+
+  /*  When converting to/from GRAY, convert to the new type's builtin
+   *  profile if none was passed.
+   */
+  if (old_type == GIMP_GRAY ||
+      new_type == GIMP_GRAY)
+    {
+      if (! dest_profile && gimp_image_get_color_profile (image))
+        dest_profile = gimp_image_get_builtin_color_profile (image);
+    }
+
+  while ((drawable = gimp_object_queue_pop (queue)))
+    {
+      gimp_drawable_convert_type (drawable, image,
+                                  new_type,
+                                  gimp_drawable_get_precision (drawable),
+                                  gimp_drawable_has_alpha (drawable),
+                                  dest_profile,
+                                  GEGL_DITHER_NONE, GEGL_DITHER_NONE,
+                                  TRUE, progress);
+    }
+
+  if (old_type == GIMP_INDEXED)
+    gimp_image_unset_colormap (image, TRUE);
+
+  /*  When converting to/from GRAY, set the new profile.
+   */
+  if (old_type == GIMP_GRAY ||
+      new_type == GIMP_GRAY)
+    {
+      if (gimp_image_get_color_profile (image))
+        gimp_image_set_color_profile (image, dest_profile, NULL);
+      else
+        gimp_color_managed_profile_changed (GIMP_COLOR_MANAGED (image));
+    }
+
+  gimp_image_undo_group_end (image);
+
+  gimp_image_mode_changed (image);
+  g_object_thaw_notify (G_OBJECT (image));
+
+  g_object_unref (queue);
+
+  gimp_unset_busy (image->gimp);
+
+  return TRUE;
+}
diff --git a/app/core/gimpimage-convert-type.h b/app/core/gimpimage-convert-type.h
new file mode 100644
index 0000000..53c6950
--- /dev/null
+++ b/app/core/gimpimage-convert-type.h
@@ -0,0 +1,29 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_IMAGE_CONVERT_TYPE_H__
+#define __GIMP_IMAGE_CONVERT_TYPE_H__
+
+
+gboolean   gimp_image_convert_type (GimpImage          *image,
+                                    GimpImageBaseType   new_type,
+                                    GimpColorProfile   *dest_profile,
+                                    GimpProgress       *progress,
+                                    GError            **error);
+
+
+#endif  /*  __GIMP_IMAGE_CONVERT_TYPE_H__  */
diff --git a/app/core/gimpimage-crop.c b/app/core/gimpimage-crop.c
new file mode 100644
index 0000000..c6814d4
--- /dev/null
+++ b/app/core/gimpimage-crop.c
@@ -0,0 +1,234 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gimp.h"
+#include "gimpcontext.h"
+#include "gimpguide.h"
+#include "gimpimage.h"
+#include "gimpimage-crop.h"
+#include "gimpimage-guides.h"
+#include "gimpimage-sample-points.h"
+#include "gimpimage-undo.h"
+#include "gimpimage-undo-push.h"
+#include "gimplayer.h"
+#include "gimpsamplepoint.h"
+
+#include "gimp-intl.h"
+
+
+/*  public functions  */
+
+void
+gimp_image_crop (GimpImage    *image,
+                 GimpContext  *context,
+                 GimpFillType  fill_type,
+                 gint          x,
+                 gint          y,
+                 gint          width,
+                 gint          height,
+                 gboolean      crop_layers)
+{
+  GList *list;
+  gint   previous_width;
+  gint   previous_height;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  previous_width  = gimp_image_get_width  (image);
+  previous_height = gimp_image_get_height (image);
+
+  /*  Make sure new width and height are non-zero  */
+  if (width < 1 || height < 1)
+    return;
+
+  gimp_set_busy (image->gimp);
+
+  g_object_freeze_notify (G_OBJECT (image));
+
+  if (crop_layers)
+    gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_IMAGE_CROP,
+                                 C_("undo-type", "Crop Image"));
+  else
+    gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_IMAGE_RESIZE,
+                                 C_("undo-type", "Resize Image"));
+
+  /*  Push the image size to the stack  */
+  gimp_image_undo_push_image_size (image, NULL,
+                                   x, y, width, height);
+
+  /*  Set the new width and height  */
+  g_object_set (image,
+                "width",  width,
+                "height", height,
+                NULL);
+
+  /*  Resize all channels  */
+  for (list = gimp_image_get_channel_iter (image);
+       list;
+       list = g_list_next (list))
+    {
+      GimpItem *item = list->data;
+
+      gimp_item_resize (item, context, GIMP_FILL_TRANSPARENT,
+                        width, height, -x, -y);
+    }
+
+  /*  Resize all vectors  */
+  for (list = gimp_image_get_vectors_iter (image);
+       list;
+       list = g_list_next (list))
+    {
+      GimpItem *item = list->data;
+
+      gimp_item_resize (item, context, GIMP_FILL_TRANSPARENT,
+                        width, height, -x, -y);
+    }
+
+  /*  Don't forget the selection mask!  */
+  gimp_item_resize (GIMP_ITEM (gimp_image_get_mask (image)),
+                    context, GIMP_FILL_TRANSPARENT,
+                    width, height, -x, -y);
+
+  /*  crop all layers  */
+  list = gimp_image_get_layer_iter (image);
+
+  while (list)
+    {
+      GimpItem *item = list->data;
+
+      list = g_list_next (list);
+
+      gimp_item_translate (item, -x, -y, TRUE);
+
+      if (crop_layers && ! gimp_item_is_content_locked (item))
+        {
+          gint off_x, off_y;
+          gint lx1, ly1, lx2, ly2;
+
+          gimp_item_get_offset (item, &off_x, &off_y);
+
+          lx1 = CLAMP (off_x, 0, gimp_image_get_width  (image));
+          ly1 = CLAMP (off_y, 0, gimp_image_get_height (image));
+          lx2 = CLAMP (gimp_item_get_width  (item) + off_x,
+                       0, gimp_image_get_width (image));
+          ly2 = CLAMP (gimp_item_get_height (item) + off_y,
+                       0, gimp_image_get_height (image));
+
+          width  = lx2 - lx1;
+          height = ly2 - ly1;
+
+          if (width > 0 && height > 0)
+            {
+              gimp_item_resize (item, context, fill_type,
+                                width, height,
+                                -(lx1 - off_x),
+                                -(ly1 - off_y));
+            }
+          else
+            {
+              gimp_image_remove_layer (image, GIMP_LAYER (item),
+                                       TRUE, NULL);
+            }
+        }
+    }
+
+  /*  Reposition or remove guides  */
+  list = gimp_image_get_guides (image);
+
+  while (list)
+    {
+      GimpGuide *guide        = list->data;
+      gboolean   remove_guide = FALSE;
+      gint       position     = gimp_guide_get_position (guide);
+
+      list = g_list_next (list);
+
+      switch (gimp_guide_get_orientation (guide))
+        {
+        case GIMP_ORIENTATION_HORIZONTAL:
+          position -= y;
+          if ((position < 0) || (position > height))
+            remove_guide = TRUE;
+          break;
+
+        case GIMP_ORIENTATION_VERTICAL:
+          position -= x;
+          if ((position < 0) || (position > width))
+            remove_guide = TRUE;
+          break;
+
+        default:
+          break;
+        }
+
+      if (remove_guide)
+        gimp_image_remove_guide (image, guide, TRUE);
+      else if (position != gimp_guide_get_position (guide))
+        gimp_image_move_guide (image, guide, position, TRUE);
+    }
+
+  /*  Reposition or remove sample points  */
+  list = gimp_image_get_sample_points (image);
+
+  while (list)
+    {
+      GimpSamplePoint *sample_point        = list->data;
+      gboolean         remove_sample_point = FALSE;
+      gint             old_x;
+      gint             old_y;
+      gint             new_x;
+      gint             new_y;
+
+      list = g_list_next (list);
+
+      gimp_sample_point_get_position (sample_point, &old_x, &old_y);
+      new_x = old_x;
+      new_y = old_y;
+
+      new_y -= y;
+      if ((new_y < 0) || (new_y > height))
+       remove_sample_point = TRUE;
+
+      new_x -= x;
+      if ((new_x < 0) || (new_x > width))
+        remove_sample_point = TRUE;
+
+      if (remove_sample_point)
+        gimp_image_remove_sample_point (image, sample_point, TRUE);
+      else if (new_x != old_x || new_y != old_y)
+        gimp_image_move_sample_point (image, sample_point,
+                                      new_x, new_y, TRUE);
+    }
+
+  gimp_image_undo_group_end (image);
+
+  gimp_image_size_changed_detailed (image,
+                                    -x, -y,
+                                    previous_width, previous_height);
+
+  g_object_thaw_notify (G_OBJECT (image));
+
+  gimp_unset_busy (image->gimp);
+}
diff --git a/app/core/gimpimage-crop.h b/app/core/gimpimage-crop.h
new file mode 100644
index 0000000..19304da
--- /dev/null
+++ b/app/core/gimpimage-crop.h
@@ -0,0 +1,32 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_IMAGE_CROP_H__
+#define __GIMP_IMAGE_CROP_H__
+
+
+void   gimp_image_crop (GimpImage    *image,
+                        GimpContext  *context,
+                        GimpFillType  fill_type,
+                        gint          x,
+                        gint          y,
+                        gint          width,
+                        gint          height,
+                        gboolean      crop_layers);
+
+
+#endif  /* __GIMP_IMAGE_CROP_H__ */
diff --git a/app/core/gimpimage-duplicate.c b/app/core/gimpimage-duplicate.c
new file mode 100644
index 0000000..4dcaedd
--- /dev/null
+++ b/app/core/gimpimage-duplicate.c
@@ -0,0 +1,535 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+
+#include "core-types.h"
+
+#include "gegl/gimp-gegl-loops.h"
+
+#include "vectors/gimpvectors.h"
+
+#include "gimp.h"
+#include "gimpchannel.h"
+#include "gimpguide.h"
+#include "gimpimage.h"
+#include "gimpimage-color-profile.h"
+#include "gimpimage-colormap.h"
+#include "gimpimage-duplicate.h"
+#include "gimpimage-grid.h"
+#include "gimpimage-guides.h"
+#include "gimpimage-metadata.h"
+#include "gimpimage-private.h"
+#include "gimpimage-undo.h"
+#include "gimpimage-sample-points.h"
+#include "gimpitemstack.h"
+#include "gimplayer.h"
+#include "gimplayermask.h"
+#include "gimplayer-floating-selection.h"
+#include "gimpparasitelist.h"
+#include "gimpsamplepoint.h"
+
+
+static void          gimp_image_duplicate_resolution       (GimpImage *image,
+                                                            GimpImage *new_image);
+static void          gimp_image_duplicate_save_source_file (GimpImage *image,
+                                                            GimpImage *new_image);
+static void          gimp_image_duplicate_colormap         (GimpImage *image,
+                                                            GimpImage *new_image);
+static GimpItem    * gimp_image_duplicate_item             (GimpItem  *item,
+                                                            GimpImage *new_image);
+static GimpLayer   * gimp_image_duplicate_layers           (GimpImage *image,
+                                                            GimpImage *new_image);
+static GimpChannel * gimp_image_duplicate_channels         (GimpImage *image,
+                                                            GimpImage *new_image);
+static GimpVectors * gimp_image_duplicate_vectors          (GimpImage *image,
+                                                            GimpImage *new_image);
+static void          gimp_image_duplicate_floating_sel     (GimpImage *image,
+                                                            GimpImage *new_image);
+static void          gimp_image_duplicate_mask             (GimpImage *image,
+                                                            GimpImage *new_image);
+static void          gimp_image_duplicate_components       (GimpImage *image,
+                                                            GimpImage *new_image);
+static void          gimp_image_duplicate_guides           (GimpImage *image,
+                                                            GimpImage *new_image);
+static void          gimp_image_duplicate_sample_points    (GimpImage *image,
+                                                            GimpImage *new_image);
+static void          gimp_image_duplicate_grid             (GimpImage *image,
+                                                            GimpImage *new_image);
+static void          gimp_image_duplicate_metadata         (GimpImage *image,
+                                                            GimpImage *new_image);
+static void          gimp_image_duplicate_quick_mask       (GimpImage *image,
+                                                            GimpImage *new_image);
+static void          gimp_image_duplicate_parasites        (GimpImage *image,
+                                                            GimpImage *new_image);
+static void          gimp_image_duplicate_color_profile    (GimpImage *image,
+                                                            GimpImage *new_image);
+
+
+GimpImage *
+gimp_image_duplicate (GimpImage *image)
+{
+  GimpImage    *new_image;
+  GimpLayer    *active_layer;
+  GimpChannel  *active_channel;
+  GimpVectors  *active_vectors;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  gimp_set_busy_until_idle (image->gimp);
+
+  /*  Create a new image  */
+  new_image = gimp_create_image (image->gimp,
+                                 gimp_image_get_width  (image),
+                                 gimp_image_get_height (image),
+                                 gimp_image_get_base_type (image),
+                                 gimp_image_get_precision (image),
+                                 FALSE);
+  gimp_image_undo_disable (new_image);
+
+  /*  Store the source uri to be used by the save dialog  */
+  gimp_image_duplicate_save_source_file (image, new_image);
+
+  /*  Copy the colormap if necessary  */
+  gimp_image_duplicate_colormap (image, new_image);
+
+  /*  Copy resolution information  */
+  gimp_image_duplicate_resolution (image, new_image);
+
+  /*  Copy parasites first so we have a color profile  */
+  gimp_image_duplicate_parasites (image, new_image);
+  gimp_image_duplicate_color_profile (image, new_image);
+
+  /*  Copy the layers  */
+  active_layer = gimp_image_duplicate_layers (image, new_image);
+
+  /*  Copy the channels  */
+  active_channel = gimp_image_duplicate_channels (image, new_image);
+
+  /*  Copy any vectors  */
+  active_vectors = gimp_image_duplicate_vectors (image, new_image);
+
+  /*  Copy floating layer  */
+  gimp_image_duplicate_floating_sel (image, new_image);
+
+  /*  Copy the selection mask  */
+  gimp_image_duplicate_mask (image, new_image);
+
+  /*  Set active layer, active channel, active vectors  */
+  if (active_layer)
+    gimp_image_set_active_layer (new_image, active_layer);
+
+  if (active_channel)
+    gimp_image_set_active_channel (new_image, active_channel);
+
+  if (active_vectors)
+    gimp_image_set_active_vectors (new_image, active_vectors);
+
+  /*  Copy state of all color components  */
+  gimp_image_duplicate_components (image, new_image);
+
+  /*  Copy any guides  */
+  gimp_image_duplicate_guides (image, new_image);
+
+  /*  Copy any sample points  */
+  gimp_image_duplicate_sample_points (image, new_image);
+
+  /*  Copy the grid  */
+  gimp_image_duplicate_grid (image, new_image);
+
+  /*  Copy the metadata  */
+  gimp_image_duplicate_metadata (image, new_image);
+
+  /*  Copy the quick mask info  */
+  gimp_image_duplicate_quick_mask (image, new_image);
+
+  gimp_image_undo_enable (new_image);
+
+  /*  Explicitly mark image as dirty, so that its dirty time is set  */
+  gimp_image_dirty (new_image, GIMP_DIRTY_ALL);
+
+  return new_image;
+}
+
+static void
+gimp_image_duplicate_resolution (GimpImage *image,
+                                 GimpImage *new_image)
+{
+  gdouble xres;
+  gdouble yres;
+
+  gimp_image_get_resolution (image, &xres, &yres);
+  gimp_image_set_resolution (new_image, xres, yres);
+  gimp_image_set_unit (new_image, gimp_image_get_unit (image));
+}
+
+static void
+gimp_image_duplicate_save_source_file (GimpImage *image,
+                                       GimpImage *new_image)
+{
+  GFile *file = gimp_image_get_file (image);
+
+  if (file)
+    g_object_set_data_full (G_OBJECT (new_image), "gimp-image-source-file",
+                            g_object_ref (file),
+                            (GDestroyNotify) g_object_unref);
+}
+
+static void
+gimp_image_duplicate_colormap (GimpImage *image,
+                               GimpImage *new_image)
+{
+  if (gimp_image_get_base_type (new_image) == GIMP_INDEXED)
+    gimp_image_set_colormap (new_image,
+                             gimp_image_get_colormap (image),
+                             gimp_image_get_colormap_size (image),
+                             FALSE);
+}
+
+static GimpItem *
+gimp_image_duplicate_item (GimpItem  *item,
+                           GimpImage *new_image)
+{
+  GimpItem *new_item;
+
+  new_item = gimp_item_convert (item, new_image,
+                                G_TYPE_FROM_INSTANCE (item));
+
+  /*  Make sure the copied item doesn't say: "<old item> copy"  */
+  gimp_object_set_name (GIMP_OBJECT (new_item),
+                        gimp_object_get_name (item));
+
+  return new_item;
+}
+
+static GimpLayer *
+gimp_image_duplicate_layers (GimpImage *image,
+                             GimpImage *new_image)
+{
+  GimpLayer *active_layer = NULL;
+  GList     *list;
+  gint       count;
+
+  for (list = gimp_image_get_layer_iter (image), count = 0;
+       list;
+       list = g_list_next (list))
+    {
+      GimpLayer *layer = list->data;
+      GimpLayer *new_layer;
+
+      if (gimp_layer_is_floating_sel (layer))
+        continue;
+
+      new_layer = GIMP_LAYER (gimp_image_duplicate_item (GIMP_ITEM (layer),
+                                                         new_image));
+
+      /*  Make sure that if the layer has a layer mask,
+       *  its name isn't screwed up
+       */
+      if (new_layer->mask)
+        gimp_object_set_name (GIMP_OBJECT (new_layer->mask),
+                              gimp_object_get_name (layer->mask));
+
+      if (gimp_image_get_active_layer (image) == layer)
+        active_layer = new_layer;
+
+      gimp_image_add_layer (new_image, new_layer,
+                            NULL, count++, FALSE);
+    }
+
+  return active_layer;
+}
+
+static GimpChannel *
+gimp_image_duplicate_channels (GimpImage *image,
+                               GimpImage *new_image)
+{
+  GimpChannel *active_channel = NULL;
+  GList       *list;
+  gint         count;
+
+  for (list = gimp_image_get_channel_iter (image), count = 0;
+       list;
+       list = g_list_next (list))
+    {
+      GimpChannel  *channel = list->data;
+      GimpChannel  *new_channel;
+
+      new_channel = GIMP_CHANNEL (gimp_image_duplicate_item (GIMP_ITEM (channel),
+                                                             new_image));
+
+      if (gimp_image_get_active_channel (image) == channel)
+        active_channel = new_channel;
+
+      gimp_image_add_channel (new_image, new_channel,
+                              NULL, count++, FALSE);
+    }
+
+  return active_channel;
+}
+
+static GimpVectors *
+gimp_image_duplicate_vectors (GimpImage *image,
+                              GimpImage *new_image)
+{
+  GimpVectors *active_vectors = NULL;
+  GList       *list;
+  gint         count;
+
+  for (list = gimp_image_get_vectors_iter (image), count = 0;
+       list;
+       list = g_list_next (list))
+    {
+      GimpVectors  *vectors = list->data;
+      GimpVectors  *new_vectors;
+
+      new_vectors = GIMP_VECTORS (gimp_image_duplicate_item (GIMP_ITEM (vectors),
+                                                             new_image));
+
+      if (gimp_image_get_active_vectors (image) == vectors)
+        active_vectors = new_vectors;
+
+      gimp_image_add_vectors (new_image, new_vectors,
+                              NULL, count++, FALSE);
+    }
+
+  return active_vectors;
+}
+
+static void
+gimp_image_duplicate_floating_sel (GimpImage *image,
+                                   GimpImage *new_image)
+{
+  GimpLayer     *floating_sel;
+  GimpDrawable  *floating_sel_drawable;
+  GList         *floating_sel_path;
+  GimpItemStack *new_item_stack;
+  GimpLayer     *new_floating_sel;
+  GimpDrawable  *new_floating_sel_drawable;
+
+  floating_sel = gimp_image_get_floating_selection (image);
+
+  if (! floating_sel)
+    return;
+
+  floating_sel_drawable = gimp_layer_get_floating_sel_drawable (floating_sel);
+
+  if (GIMP_IS_LAYER_MASK (floating_sel_drawable))
+    {
+      GimpLayer *layer;
+
+      layer = gimp_layer_mask_get_layer (GIMP_LAYER_MASK (floating_sel_drawable));
+
+      floating_sel_path = gimp_item_get_path (GIMP_ITEM (layer));
+
+      new_item_stack = GIMP_ITEM_STACK (gimp_image_get_layers (new_image));
+    }
+  else
+    {
+      floating_sel_path = gimp_item_get_path (GIMP_ITEM (floating_sel_drawable));
+
+      if (GIMP_IS_LAYER (floating_sel_drawable))
+        new_item_stack = GIMP_ITEM_STACK (gimp_image_get_layers (new_image));
+      else
+        new_item_stack = GIMP_ITEM_STACK (gimp_image_get_channels (new_image));
+    }
+
+  /*  adjust path[0] for the floating layer missing in new_image  */
+  floating_sel_path->data =
+    GUINT_TO_POINTER (GPOINTER_TO_UINT (floating_sel_path->data) - 1);
+
+  if (GIMP_IS_LAYER (floating_sel_drawable))
+    {
+      new_floating_sel =
+        GIMP_LAYER (gimp_image_duplicate_item (GIMP_ITEM (floating_sel),
+                                               new_image));
+    }
+  else
+    {
+      /*  can't use gimp_item_convert() for floating selections of channels
+       *  or layer masks because they maybe don't have a normal layer's type
+       */
+      new_floating_sel =
+        GIMP_LAYER (gimp_item_duplicate (GIMP_ITEM (floating_sel),
+                                         G_TYPE_FROM_INSTANCE (floating_sel)));
+      gimp_item_set_image (GIMP_ITEM (new_floating_sel), new_image);
+
+      gimp_object_set_name (GIMP_OBJECT (new_floating_sel),
+                            gimp_object_get_name (floating_sel));
+    }
+
+  /*  Make sure the copied layer doesn't say: "<old layer> copy"  */
+  gimp_object_set_name (GIMP_OBJECT (new_floating_sel),
+                        gimp_object_get_name (floating_sel));
+
+  new_floating_sel_drawable =
+    GIMP_DRAWABLE (gimp_item_stack_get_item_by_path (new_item_stack,
+                                                     floating_sel_path));
+
+  if (GIMP_IS_LAYER_MASK (floating_sel_drawable))
+    new_floating_sel_drawable =
+      GIMP_DRAWABLE (gimp_layer_get_mask (GIMP_LAYER (new_floating_sel_drawable)));
+
+  floating_sel_attach (new_floating_sel, new_floating_sel_drawable);
+
+  g_list_free (floating_sel_path);
+}
+
+static void
+gimp_image_duplicate_mask (GimpImage *image,
+                           GimpImage *new_image)
+{
+  GimpDrawable *mask;
+  GimpDrawable *new_mask;
+
+  mask     = GIMP_DRAWABLE (gimp_image_get_mask (image));
+  new_mask = GIMP_DRAWABLE (gimp_image_get_mask (new_image));
+
+  gimp_gegl_buffer_copy (gimp_drawable_get_buffer (mask), NULL, GEGL_ABYSS_NONE,
+                         gimp_drawable_get_buffer (new_mask), NULL);
+
+  GIMP_CHANNEL (new_mask)->bounds_known   = FALSE;
+  GIMP_CHANNEL (new_mask)->boundary_known = FALSE;
+}
+
+static void
+gimp_image_duplicate_components (GimpImage *image,
+                                 GimpImage *new_image)
+{
+  GimpImagePrivate *private     = GIMP_IMAGE_GET_PRIVATE (image);
+  GimpImagePrivate *new_private = GIMP_IMAGE_GET_PRIVATE (new_image);
+  gint              count;
+
+  for (count = 0; count < MAX_CHANNELS; count++)
+    {
+      new_private->visible[count] = private->visible[count];
+      new_private->active[count]  = private->active[count];
+    }
+}
+
+static void
+gimp_image_duplicate_guides (GimpImage *image,
+                             GimpImage *new_image)
+{
+  GList *list;
+
+  for (list = gimp_image_get_guides (image);
+       list;
+       list = g_list_next (list))
+    {
+      GimpGuide *guide    = list->data;
+      gint       position = gimp_guide_get_position (guide);
+
+      switch (gimp_guide_get_orientation (guide))
+        {
+        case GIMP_ORIENTATION_HORIZONTAL:
+          gimp_image_add_hguide (new_image, position, FALSE);
+          break;
+
+        case GIMP_ORIENTATION_VERTICAL:
+          gimp_image_add_vguide (new_image, position, FALSE);
+          break;
+
+        default:
+          g_error ("Unknown guide orientation.\n");
+        }
+    }
+}
+
+static void
+gimp_image_duplicate_sample_points (GimpImage *image,
+                                    GimpImage *new_image)
+{
+  GList *list;
+
+  for (list = gimp_image_get_sample_points (image);
+       list;
+       list = g_list_next (list))
+    {
+      GimpSamplePoint *sample_point = list->data;
+      gint             x;
+      gint             y;
+
+      gimp_sample_point_get_position (sample_point, &x, &y);
+
+      gimp_image_add_sample_point_at_pos (new_image, x, y, FALSE);
+    }
+}
+
+static void
+gimp_image_duplicate_grid (GimpImage *image,
+                           GimpImage *new_image)
+{
+  if (gimp_image_get_grid (image))
+    gimp_image_set_grid (new_image, gimp_image_get_grid (image), FALSE);
+}
+
+static void
+gimp_image_duplicate_metadata (GimpImage *image,
+                               GimpImage *new_image)
+{
+  GimpMetadata *metadata = gimp_image_get_metadata (image);
+
+  if (metadata)
+    {
+      metadata = gimp_metadata_duplicate (metadata);
+      gimp_image_set_metadata (new_image, metadata, FALSE);
+      g_object_unref (metadata);
+    }
+}
+
+static void
+gimp_image_duplicate_quick_mask (GimpImage *image,
+                                 GimpImage *new_image)
+{
+  GimpImagePrivate *private     = GIMP_IMAGE_GET_PRIVATE (image);
+  GimpImagePrivate *new_private = GIMP_IMAGE_GET_PRIVATE (new_image);
+
+  new_private->quick_mask_state    = private->quick_mask_state;
+  new_private->quick_mask_inverted = private->quick_mask_inverted;
+  new_private->quick_mask_color    = private->quick_mask_color;
+}
+
+static void
+gimp_image_duplicate_parasites (GimpImage *image,
+                                GimpImage *new_image)
+{
+  GimpImagePrivate *private     = GIMP_IMAGE_GET_PRIVATE (image);
+  GimpImagePrivate *new_private = GIMP_IMAGE_GET_PRIVATE (new_image);
+
+  if (private->parasites)
+    {
+      g_object_unref (new_private->parasites);
+      new_private->parasites = gimp_parasite_list_copy (private->parasites);
+    }
+}
+
+static void
+gimp_image_duplicate_color_profile (GimpImage *image,
+                                    GimpImage *new_image)
+{
+  GimpColorProfile *profile          = gimp_image_get_color_profile (image);
+  gboolean          is_color_managed = gimp_image_get_is_color_managed (image);
+
+  gimp_image_set_color_profile    (new_image, profile, NULL);
+  gimp_image_set_is_color_managed (new_image, is_color_managed, FALSE);
+}
diff --git a/app/core/gimpimage-duplicate.h b/app/core/gimpimage-duplicate.h
new file mode 100644
index 0000000..cbf55a2
--- /dev/null
+++ b/app/core/gimpimage-duplicate.h
@@ -0,0 +1,25 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_IMAGE_DUPLICATE_H__
+#define __GIMP_IMAGE_DUPLICATE_H__
+
+
+GimpImage * gimp_image_duplicate (GimpImage *image);
+
+
+#endif  /*  __GIMP_IMAGE_DUPLICATE_H__  */
diff --git a/app/core/gimpimage-flip.c b/app/core/gimpimage-flip.c
new file mode 100644
index 0000000..5db05fe
--- /dev/null
+++ b/app/core/gimpimage-flip.c
@@ -0,0 +1,276 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpmath/gimpmath.h"
+
+#include "core-types.h"
+
+#include "gimp.h"
+#include "gimpchannel.h"
+#include "gimpcontainer.h"
+#include "gimpcontext.h"
+#include "gimpguide.h"
+#include "gimpimage.h"
+#include "gimpimage-flip.h"
+#include "gimpimage-guides.h"
+#include "gimpimage-sample-points.h"
+#include "gimpimage-undo.h"
+#include "gimpimage-undo-push.h"
+#include "gimpitem.h"
+#include "gimpobjectqueue.h"
+#include "gimpprogress.h"
+#include "gimpsamplepoint.h"
+
+
+/*  local function prototypes  */
+
+static void    gimp_image_flip_guides        (GimpImage           *image,
+                                              GimpOrientationType  flip_type,
+                                              gdouble              axis);
+static void    gimp_image_flip_sample_points (GimpImage           *image,
+                                              GimpOrientationType  flip_type,
+                                              gdouble              axis);
+
+
+/*  private functions  */
+
+static void
+gimp_image_flip_guides (GimpImage           *image,
+                        GimpOrientationType  flip_type,
+                        gdouble              axis)
+{
+  gint   width  = gimp_image_get_width  (image);
+  gint   height = gimp_image_get_height (image);
+  GList *iter;
+
+  for (iter = gimp_image_get_guides (image); iter;)
+    {
+      GimpGuide *guide    = iter->data;
+      gint       position = gimp_guide_get_position (guide);
+
+      iter = g_list_next (iter);
+
+      position = SIGNED_ROUND (2.0 * axis - position);
+
+      switch (gimp_guide_get_orientation (guide))
+        {
+        case GIMP_ORIENTATION_HORIZONTAL:
+          if (flip_type == GIMP_ORIENTATION_VERTICAL)
+            {
+              if (position >= 0 && position <= height)
+                gimp_image_move_guide (image, guide, position, TRUE);
+              else
+                gimp_image_remove_guide (image, guide, TRUE);
+            }
+          break;
+
+        case GIMP_ORIENTATION_VERTICAL:
+          if (flip_type == GIMP_ORIENTATION_HORIZONTAL)
+            {
+              if (position >= 0 && position <= width)
+                gimp_image_move_guide (image, guide, position, TRUE);
+              else
+                gimp_image_remove_guide (image, guide, TRUE);
+            }
+          break;
+
+        case GIMP_ORIENTATION_UNKNOWN:
+          g_return_if_reached ();
+        }
+    }
+}
+
+static void
+gimp_image_flip_sample_points (GimpImage           *image,
+                               GimpOrientationType  flip_type,
+                               gdouble              axis)
+{
+  gint   width  = gimp_image_get_width  (image);
+  gint   height = gimp_image_get_height (image);
+  GList *iter;
+
+  for (iter = gimp_image_get_sample_points (image); iter;)
+    {
+      GimpSamplePoint *sample_point = iter->data;
+      gint             x;
+      gint             y;
+
+      iter = g_list_next (iter);
+
+      gimp_sample_point_get_position (sample_point, &x, &y);
+
+      switch (flip_type)
+        {
+        case GIMP_ORIENTATION_HORIZONTAL:
+          x = SIGNED_ROUND (2.0 * axis - x);
+          break;
+
+        case GIMP_ORIENTATION_VERTICAL:
+          y = SIGNED_ROUND (2.0 * axis - y);
+          break;
+
+        case GIMP_ORIENTATION_UNKNOWN:
+          g_return_if_reached ();
+        }
+
+      if (x >= 0 && x < width &&
+          y >= 0 && y < height)
+        {
+          gimp_image_move_sample_point (image, sample_point, x, y, TRUE);
+        }
+      else
+        {
+          gimp_image_remove_sample_point (image, sample_point, TRUE);
+        }
+    }
+}
+
+
+/*  public functions  */
+
+void
+gimp_image_flip (GimpImage           *image,
+                 GimpContext         *context,
+                 GimpOrientationType  flip_type,
+                 GimpProgress        *progress)
+{
+  gdouble axis = 0.0;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+  g_return_if_fail (progress == NULL || GIMP_IS_PROGRESS (progress));
+
+  switch (flip_type)
+    {
+    case GIMP_ORIENTATION_HORIZONTAL:
+      axis = gimp_image_get_width (image) / 2.0;
+      break;
+
+    case GIMP_ORIENTATION_VERTICAL:
+      axis = gimp_image_get_height (image) / 2.0;
+      break;
+
+    case GIMP_ORIENTATION_UNKNOWN:
+      g_return_if_reached ();
+    }
+
+  gimp_image_flip_full (image, context, flip_type, axis,
+                        GIMP_TRANSFORM_RESIZE_CLIP, progress);
+}
+
+void
+gimp_image_flip_full (GimpImage           *image,
+                      GimpContext         *context,
+                      GimpOrientationType  flip_type,
+                      gdouble              axis,
+                      gboolean             clip_result,
+                      GimpProgress        *progress)
+{
+  GimpObjectQueue *queue;
+  GimpItem        *item;
+  gint             width;
+  gint             height;
+  gint             offset_x = 0;
+  gint             offset_y = 0;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+  g_return_if_fail (progress == NULL || GIMP_IS_PROGRESS (progress));
+
+  width  = gimp_image_get_width  (image);
+  height = gimp_image_get_height (image);
+
+  if (! clip_result)
+    {
+      switch (flip_type)
+        {
+        case GIMP_ORIENTATION_HORIZONTAL:
+          offset_x = SIGNED_ROUND (2.0 * axis - width);
+          axis     = width / 2.0;
+          break;
+
+        case GIMP_ORIENTATION_VERTICAL:
+          offset_y = SIGNED_ROUND (2.0 * axis - height);
+          axis     = height / 2.0;
+          break;
+
+        case GIMP_ORIENTATION_UNKNOWN:
+          g_return_if_reached ();
+        }
+    }
+
+  gimp_set_busy (image->gimp);
+
+  queue    = gimp_object_queue_new (progress);
+  progress = GIMP_PROGRESS (queue);
+
+  gimp_object_queue_push_container (queue, gimp_image_get_layers (image));
+  gimp_object_queue_push (queue, gimp_image_get_mask (image));
+  gimp_object_queue_push_container (queue, gimp_image_get_channels (image));
+  gimp_object_queue_push_container (queue, gimp_image_get_vectors (image));
+
+  gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_IMAGE_FLIP, NULL);
+
+  /*  Flip all layers, channels (including selection mask), and vectors  */
+  while ((item = gimp_object_queue_pop (queue)))
+    {
+      gboolean clip = FALSE;
+
+      if (GIMP_IS_CHANNEL (item))
+        clip = clip_result;
+
+      gimp_item_flip (item, context, flip_type, axis, clip);
+
+      gimp_progress_set_value (progress, 1.0);
+    }
+
+  /*  Flip all Guides  */
+  gimp_image_flip_guides (image, flip_type, axis);
+
+  /*  Flip all sample points  */
+  gimp_image_flip_sample_points (image, flip_type, axis);
+
+  if (offset_x || offset_y)
+    {
+      gimp_image_undo_push_image_size (image,
+                                       NULL,
+                                       offset_x,
+                                       offset_y,
+                                       width,
+                                       height);
+    }
+
+  gimp_image_undo_group_end (image);
+
+  g_object_unref (queue);
+
+  if (offset_x || offset_y)
+    {
+      gimp_image_size_changed_detailed (image,
+                                        -offset_x,
+                                        -offset_y,
+                                        width,
+                                        height);
+    }
+
+  gimp_unset_busy (image->gimp);
+}
diff --git a/app/core/gimpimage-flip.h b/app/core/gimpimage-flip.h
new file mode 100644
index 0000000..5fa6ce6
--- /dev/null
+++ b/app/core/gimpimage-flip.h
@@ -0,0 +1,34 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattisbvf
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_IMAGE_FLIP_H__
+#define __GIMP_IMAGE_FLIP_H__
+
+
+void   gimp_image_flip      (GimpImage           *image,
+                             GimpContext         *context,
+                             GimpOrientationType  flip_type,
+                             GimpProgress        *progress);
+void   gimp_image_flip_full (GimpImage           *image,
+                             GimpContext         *context,
+                             GimpOrientationType  flip_type,
+                             gdouble              axis,
+                             gboolean             clip_result,
+                             GimpProgress        *progress);
+
+
+#endif /* __GIMP_IMAGE_FLIP_H__ */
diff --git a/app/core/gimpimage-grid.c b/app/core/gimpimage-grid.c
new file mode 100644
index 0000000..dec1850
--- /dev/null
+++ b/app/core/gimpimage-grid.c
@@ -0,0 +1,67 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * GimpGrid
+ * Copyright (C) 2003  Henrik Brix Andersen <brix@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpconfig/gimpconfig.h"
+
+#include "core-types.h"
+
+#include "gimpgrid.h"
+#include "gimpimage.h"
+#include "gimpimage-grid.h"
+#include "gimpimage-private.h"
+#include "gimpimage-undo-push.h"
+
+#include "gimp-intl.h"
+
+
+GimpGrid *
+gimp_image_get_grid (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->grid;
+}
+
+void
+gimp_image_set_grid (GimpImage *image,
+                     GimpGrid  *grid,
+                     gboolean   push_undo)
+{
+  GimpImagePrivate *private;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (GIMP_IS_GRID (grid));
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  if (gimp_config_is_equal_to (GIMP_CONFIG (private->grid), GIMP_CONFIG (grid)))
+    return;
+
+  if (push_undo)
+    gimp_image_undo_push_image_grid (image,
+                                     C_("undo-type", "Grid"), private->grid);
+
+  gimp_config_sync (G_OBJECT (grid), G_OBJECT (private->grid), 0);
+}
diff --git a/app/core/gimpimage-grid.h b/app/core/gimpimage-grid.h
new file mode 100644
index 0000000..c2a4a3f
--- /dev/null
+++ b/app/core/gimpimage-grid.h
@@ -0,0 +1,31 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattisbvf
+ *
+ * GimpGrid
+ * Copyright (C) 2003  Henrik Brix Andersen <brix@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_IMAGE_GRID_H__
+#define __GIMP_IMAGE_GRID_H__
+
+
+GimpGrid * gimp_image_get_grid (GimpImage *image);
+void       gimp_image_set_grid (GimpImage *image,
+                                GimpGrid  *grid,
+                                gboolean   push_undo);
+
+
+#endif /* __GIMP_IMAGE_GRID_H__ */
diff --git a/app/core/gimpimage-guides.c b/app/core/gimpimage-guides.c
new file mode 100644
index 0000000..a265d1e
--- /dev/null
+++ b/app/core/gimpimage-guides.c
@@ -0,0 +1,216 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gimp.h"
+#include "gimpimage.h"
+#include "gimpguide.h"
+#include "gimpimage-guides.h"
+#include "gimpimage-private.h"
+#include "gimpimage-undo-push.h"
+
+#include "gimp-intl.h"
+
+
+/*  public functions  */
+
+GimpGuide *
+gimp_image_add_hguide (GimpImage *image,
+                       gint       position,
+                       gboolean   push_undo)
+{
+  GimpGuide *guide;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (position >= 0 &&
+                        position <= gimp_image_get_height (image), NULL);
+
+  guide = gimp_guide_new (GIMP_ORIENTATION_HORIZONTAL,
+                          image->gimp->next_guide_ID++);
+
+  if (push_undo)
+    gimp_image_undo_push_guide (image,
+                                C_("undo-type", "Add Horizontal Guide"), guide);
+
+  gimp_image_add_guide (image, guide, position);
+  g_object_unref (G_OBJECT (guide));
+
+  return guide;
+}
+
+GimpGuide *
+gimp_image_add_vguide (GimpImage *image,
+                       gint       position,
+                       gboolean   push_undo)
+{
+  GimpGuide *guide;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (position >= 0 &&
+                        position <= gimp_image_get_width (image), NULL);
+
+  guide = gimp_guide_new (GIMP_ORIENTATION_VERTICAL,
+                          image->gimp->next_guide_ID++);
+
+  if (push_undo)
+    gimp_image_undo_push_guide (image,
+                                C_("undo-type", "Add Vertical Guide"), guide);
+
+  gimp_image_add_guide (image, guide, position);
+  g_object_unref (guide);
+
+  return guide;
+}
+
+void
+gimp_image_add_guide (GimpImage *image,
+                      GimpGuide *guide,
+                      gint       position)
+{
+  GimpImagePrivate *private;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (GIMP_IS_GUIDE (guide));
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  private->guides = g_list_prepend (private->guides, guide);
+
+  gimp_guide_set_position (guide, position);
+  g_object_ref (guide);
+
+  gimp_image_guide_added (image, guide);
+}
+
+void
+gimp_image_remove_guide (GimpImage *image,
+                         GimpGuide *guide,
+                         gboolean   push_undo)
+{
+  GimpImagePrivate *private;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (GIMP_IS_GUIDE (guide));
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  if (gimp_guide_is_custom (guide))
+    push_undo = FALSE;
+
+  if (push_undo)
+    gimp_image_undo_push_guide (image, C_("undo-type", "Remove Guide"), guide);
+
+  private->guides = g_list_remove (private->guides, guide);
+  gimp_aux_item_removed (GIMP_AUX_ITEM (guide));
+
+  gimp_image_guide_removed (image, guide);
+
+  gimp_guide_set_position (guide, GIMP_GUIDE_POSITION_UNDEFINED);
+  g_object_unref (guide);
+}
+
+void
+gimp_image_move_guide (GimpImage *image,
+                       GimpGuide *guide,
+                       gint       position,
+                       gboolean   push_undo)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (GIMP_IS_GUIDE (guide));
+  g_return_if_fail (position >= 0);
+
+  if (gimp_guide_get_orientation (guide) == GIMP_ORIENTATION_HORIZONTAL)
+    g_return_if_fail (position <= gimp_image_get_height (image));
+  else
+    g_return_if_fail (position <= gimp_image_get_width (image));
+
+  if (gimp_guide_is_custom (guide))
+    push_undo = FALSE;
+
+  if (push_undo)
+    gimp_image_undo_push_guide (image, C_("undo-type", "Move Guide"), guide);
+
+  gimp_guide_set_position (guide, position);
+
+  gimp_image_guide_moved (image, guide);
+}
+
+GList *
+gimp_image_get_guides (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->guides;
+}
+
+GimpGuide *
+gimp_image_get_guide (GimpImage *image,
+                      guint32    id)
+{
+  GList *guides;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  for (guides = GIMP_IMAGE_GET_PRIVATE (image)->guides;
+       guides;
+       guides = g_list_next (guides))
+    {
+      GimpGuide *guide = guides->data;
+
+      if (gimp_aux_item_get_ID (GIMP_AUX_ITEM (guide)) == id)
+        return guide;
+    }
+
+  return NULL;
+}
+
+GimpGuide *
+gimp_image_get_next_guide (GimpImage *image,
+                           guint32    id,
+                           gboolean  *guide_found)
+{
+  GList *guides;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (guide_found != NULL, NULL);
+
+  if (id == 0)
+    *guide_found = TRUE;
+  else
+    *guide_found = FALSE;
+
+  for (guides = GIMP_IMAGE_GET_PRIVATE (image)->guides;
+       guides;
+       guides = g_list_next (guides))
+    {
+      GimpGuide *guide = guides->data;
+
+      if (*guide_found) /* this is the first guide after the found one */
+        return guide;
+
+      if (gimp_aux_item_get_ID (GIMP_AUX_ITEM (guide)) == id) /* found it, next one will be returned */
+        *guide_found = TRUE;
+    }
+
+  return NULL;
+}
diff --git a/app/core/gimpimage-guides.h b/app/core/gimpimage-guides.h
new file mode 100644
index 0000000..7f9706e
--- /dev/null
+++ b/app/core/gimpimage-guides.h
@@ -0,0 +1,54 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_IMAGE_GUIDES_H__
+#define __GIMP_IMAGE_GUIDES_H__
+
+
+/*  public guide adding API
+ */
+GimpGuide * gimp_image_add_hguide     (GimpImage *image,
+                                       gint       position,
+                                       gboolean   push_undo);
+GimpGuide * gimp_image_add_vguide     (GimpImage *image,
+                                       gint       position,
+                                       gboolean   push_undo);
+
+/*  internal guide adding API, does not check the guide's position and
+ *  is publicly declared only to be used from undo
+ */
+void        gimp_image_add_guide      (GimpImage *image,
+                                       GimpGuide *guide,
+                                       gint       position);
+
+void        gimp_image_remove_guide   (GimpImage *image,
+                                       GimpGuide *guide,
+                                       gboolean   push_undo);
+void        gimp_image_move_guide     (GimpImage *image,
+                                       GimpGuide *guide,
+                                       gint       position,
+                                       gboolean   push_undo);
+
+GList     * gimp_image_get_guides     (GimpImage *image);
+GimpGuide * gimp_image_get_guide      (GimpImage *image,
+                                       guint32    id);
+GimpGuide * gimp_image_get_next_guide (GimpImage *image,
+                                       guint32    id,
+                                       gboolean  *guide_found);
+
+
+#endif /* __GIMP_IMAGE_GUIDES_H__ */
diff --git a/app/core/gimpimage-item-list.c b/app/core/gimpimage-item-list.c
new file mode 100644
index 0000000..6b6bad4
--- /dev/null
+++ b/app/core/gimpimage-item-list.c
@@ -0,0 +1,401 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+
+#include "core-types.h"
+
+#include "gimpcontext.h"
+#include "gimpimage.h"
+#include "gimpimage-item-list.h"
+#include "gimpimage-undo.h"
+#include "gimpitem.h"
+#include "gimpobjectqueue.h"
+#include "gimpprogress.h"
+
+#include "gimp-intl.h"
+
+
+/*  public functions  */
+
+gboolean
+gimp_image_item_list_bounds (GimpImage *image,
+                             GList     *list,
+                             gint      *x,
+                             gint      *y,
+                             gint      *width,
+                             gint      *height)
+{
+  GList    *l;
+  gboolean  bounds = FALSE;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+  g_return_val_if_fail (x != 0, FALSE);
+  g_return_val_if_fail (y != 0, FALSE);
+  g_return_val_if_fail (width != 0, FALSE);
+  g_return_val_if_fail (height != 0, FALSE);
+
+  for (l = list; l; l = g_list_next (l))
+    {
+      GimpItem *item = l->data;
+      gint      tmp_x, tmp_y;
+      gint      tmp_w, tmp_h;
+
+      if (gimp_item_bounds (item, &tmp_x, &tmp_y, &tmp_w, &tmp_h))
+        {
+          gint off_x, off_y;
+
+          gimp_item_get_offset (item, &off_x, &off_y);
+
+          if (bounds)
+            {
+              gimp_rectangle_union (*x, *y, *width, *height,
+                                    tmp_x + off_x, tmp_y + off_y,
+                                    tmp_w, tmp_h,
+                                    x, y, width, height);
+            }
+          else
+            {
+              *x      = tmp_x + off_x;
+              *y      = tmp_y + off_y;
+              *width  = tmp_w;
+              *height = tmp_h;
+
+              bounds = TRUE;
+            }
+        }
+    }
+
+  if (! bounds)
+    {
+      *x      = 0;
+      *y      = 0;
+      *width  = gimp_image_get_width  (image);
+      *height = gimp_image_get_height (image);
+    }
+
+  return bounds;
+}
+
+void
+gimp_image_item_list_translate (GimpImage *image,
+                                GList     *list,
+                                gint       offset_x,
+                                gint       offset_y,
+                                gboolean   push_undo)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  if (list)
+    {
+      GList *l;
+
+      if (list->next)
+        {
+          if (push_undo)
+            {
+              gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_ITEM_DISPLACE,
+                                           C_("undo-type", "Translate Items"));
+            }
+
+          for (l = list; l; l = g_list_next (l))
+            gimp_item_start_transform (GIMP_ITEM (l->data), push_undo);
+        }
+
+      for (l = list; l; l = g_list_next (l))
+        gimp_item_translate (GIMP_ITEM (l->data),
+                             offset_x, offset_y, push_undo);
+
+      if (list->next)
+        {
+          for (l = list; l; l = g_list_next (l))
+            gimp_item_end_transform (GIMP_ITEM (l->data), push_undo);
+
+          if (push_undo)
+            gimp_image_undo_group_end (image);
+        }
+    }
+}
+
+void
+gimp_image_item_list_flip (GimpImage           *image,
+                           GList               *list,
+                           GimpContext         *context,
+                           GimpOrientationType  flip_type,
+                           gdouble              axis,
+                           gboolean             clip_result)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  if (list)
+    {
+      GList *l;
+
+      if (list->next)
+        {
+          gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_TRANSFORM,
+                                       C_("undo-type", "Flip Items"));
+
+          for (l = list; l; l = g_list_next (l))
+            gimp_item_start_transform (GIMP_ITEM (l->data), TRUE);
+        }
+
+      for (l = list; l; l = g_list_next (l))
+        {
+          GimpItem *item = l->data;
+
+          gimp_item_flip (item, context,
+                          flip_type, axis,
+                          gimp_item_get_clip (item, clip_result));
+        }
+
+      if (list->next)
+        {
+          for (l = list; l; l = g_list_next (l))
+            gimp_item_end_transform (GIMP_ITEM (l->data), TRUE);
+
+          gimp_image_undo_group_end (image);
+        }
+    }
+}
+
+void
+gimp_image_item_list_rotate (GimpImage        *image,
+                             GList            *list,
+                             GimpContext      *context,
+                             GimpRotationType  rotate_type,
+                             gdouble           center_x,
+                             gdouble           center_y,
+                             gboolean          clip_result)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  if (list)
+    {
+      GList *l;
+
+      if (list->next)
+        {
+          gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_TRANSFORM,
+                                       C_("undo-type", "Rotate Items"));
+
+          for (l = list; l; l = g_list_next (l))
+            gimp_item_start_transform (GIMP_ITEM (l->data), TRUE);
+        }
+
+      for (l = list; l; l = g_list_next (l))
+        {
+          GimpItem *item = l->data;
+
+          gimp_item_rotate (item, context,
+                            rotate_type, center_x, center_y,
+                            gimp_item_get_clip (item, clip_result));
+        }
+
+      if (list->next)
+        {
+          for (l = list; l; l = g_list_next (l))
+            gimp_item_end_transform (GIMP_ITEM (l->data), TRUE);
+
+          gimp_image_undo_group_end (image);
+        }
+    }
+}
+
+void
+gimp_image_item_list_transform (GimpImage              *image,
+                                GList                  *list,
+                                GimpContext            *context,
+                                const GimpMatrix3      *matrix,
+                                GimpTransformDirection  direction,
+                                GimpInterpolationType   interpolation_type,
+                                GimpTransformResize     clip_result,
+                                GimpProgress           *progress)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+  g_return_if_fail (progress == NULL || GIMP_IS_PROGRESS (progress));
+
+  if (list)
+    {
+      GimpObjectQueue *queue = NULL;
+      GList           *l;
+
+      if (progress)
+        {
+          queue    = gimp_object_queue_new (progress);
+          progress = GIMP_PROGRESS (queue);
+
+          gimp_object_queue_push_list (queue, list);
+        }
+
+      if (list->next)
+        {
+          gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_TRANSFORM,
+                                       C_("undo-type", "Transform Items"));
+
+          for (l = list; l; l = g_list_next (l))
+            gimp_item_start_transform (GIMP_ITEM (l->data), TRUE);
+        }
+
+      for (l = list; l; l = g_list_next (l))
+        {
+          GimpItem *item = l->data;
+
+          if (queue)
+            gimp_object_queue_pop (queue);
+
+          gimp_item_transform (item, context,
+                               matrix, direction,
+                               interpolation_type,
+                               gimp_item_get_clip (item, clip_result),
+                               progress);
+        }
+
+      if (list->next)
+        {
+          for (l = list; l; l = g_list_next (l))
+            gimp_item_end_transform (GIMP_ITEM (l->data), TRUE);
+
+          gimp_image_undo_group_end (image);
+        }
+
+      g_clear_object (&queue);
+    }
+}
+
+/**
+ * gimp_image_item_list_get_list:
+ * @image:   An @image.
+ * @type:    Which type of items to return.
+ * @set:     Set the returned items are part of.
+ *
+ * This function returns a #GList of #GimpItem<!-- -->s for which the
+ * @type and @set criterions match.
+ *
+ * Return value: The list of items.
+ **/
+GList *
+gimp_image_item_list_get_list (GimpImage        *image,
+                               GimpItemTypeMask  type,
+                               GimpItemSet       set)
+{
+  GList *all_items;
+  GList *list;
+  GList *return_list = NULL;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  if (type & GIMP_ITEM_TYPE_LAYERS)
+    {
+      all_items = gimp_image_get_layer_list (image);
+
+      for (list = all_items; list; list = g_list_next (list))
+        {
+          GimpItem *item = list->data;
+
+          if (gimp_item_is_in_set (item, set))
+            return_list = g_list_prepend (return_list, item);
+        }
+
+      g_list_free (all_items);
+    }
+
+  if (type & GIMP_ITEM_TYPE_CHANNELS)
+    {
+      all_items = gimp_image_get_channel_list (image);
+
+      for (list = all_items; list; list = g_list_next (list))
+        {
+          GimpItem *item = list->data;
+
+          if (gimp_item_is_in_set (item, set))
+            return_list = g_list_prepend (return_list, item);
+        }
+
+      g_list_free (all_items);
+    }
+
+  if (type & GIMP_ITEM_TYPE_VECTORS)
+    {
+      all_items = gimp_image_get_vectors_list (image);
+
+      for (list = all_items; list; list = g_list_next (list))
+        {
+          GimpItem *item = list->data;
+
+          if (gimp_item_is_in_set (item, set))
+            return_list = g_list_prepend (return_list, item);
+        }
+
+      g_list_free (all_items);
+    }
+
+  return g_list_reverse (return_list);
+}
+
+static GList *
+gimp_image_item_list_remove_children (GList          *list,
+                                      const GimpItem *parent)
+{
+  GList *l = list;
+
+  while (l)
+    {
+      GimpItem *item = l->data;
+
+      l = g_list_next (l);
+
+      if (gimp_viewable_is_ancestor (GIMP_VIEWABLE (parent),
+                                     GIMP_VIEWABLE (item)))
+        {
+          list = g_list_remove (list, item);
+        }
+    }
+
+  return list;
+}
+
+GList *
+gimp_image_item_list_filter (GList *list)
+{
+  GList *l;
+
+  if (! list)
+    return NULL;
+
+  for (l = list; l; l = g_list_next (l))
+    {
+      GimpItem *item = l->data;
+      GList    *next;
+
+      next = gimp_image_item_list_remove_children (g_list_next (l), item);
+
+      l->next = next;
+      if (next)
+        next->prev = l;
+    }
+
+  return list;
+}
diff --git a/app/core/gimpimage-item-list.h b/app/core/gimpimage-item-list.h
new file mode 100644
index 0000000..cd69637
--- /dev/null
+++ b/app/core/gimpimage-item-list.h
@@ -0,0 +1,63 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_IMAGE_ITEM_LIST_H__
+#define __GIMP_IMAGE_ITEM_LIST_H__
+
+
+gboolean   gimp_image_item_list_bounds    (GimpImage              *image,
+                                           GList                  *list,
+                                           gint                   *x,
+                                           gint                   *y,
+                                           gint                   *width,
+                                           gint                   *height);
+
+void       gimp_image_item_list_translate (GimpImage              *image,
+                                           GList                  *list,
+                                           gint                    offset_x,
+                                           gint                    offset_y,
+                                           gboolean                push_undo);
+void       gimp_image_item_list_flip      (GimpImage              *image,
+                                           GList                  *list,
+                                           GimpContext            *context,
+                                           GimpOrientationType     flip_type,
+                                           gdouble                 axis,
+                                           gboolean                clip_result);
+void       gimp_image_item_list_rotate    (GimpImage              *image,
+                                           GList                  *list,
+                                           GimpContext            *context,
+                                           GimpRotationType        rotate_type,
+                                           gdouble                 center_x,
+                                           gdouble                 center_y,
+                                           gboolean                clip_result);
+void       gimp_image_item_list_transform (GimpImage              *image,
+                                           GList                  *list,
+                                           GimpContext            *context,
+                                           const GimpMatrix3      *matrix,
+                                           GimpTransformDirection  direction,
+                                           GimpInterpolationType   interpolation_type,
+                                           GimpTransformResize     clip_result,
+                                           GimpProgress           *progress);
+
+GList    * gimp_image_item_list_get_list  (GimpImage              *image,
+                                           GimpItemTypeMask        type,
+                                           GimpItemSet             set);
+
+GList    * gimp_image_item_list_filter    (GList                  *list);
+
+
+#endif /* __GIMP_IMAGE_ITEM_LIST_H__ */
diff --git a/app/core/gimpimage-merge.c b/app/core/gimpimage-merge.c
new file mode 100644
index 0000000..3d96860
--- /dev/null
+++ b/app/core/gimpimage-merge.c
@@ -0,0 +1,745 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <cairo.h>
+#include <gegl.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "libgimpcolor/gimpcolor.h"
+#include "libgimpmath/gimpmath.h"
+#include "libgimpbase/gimpbase.h"
+
+#include "core-types.h"
+
+#include "gegl/gimp-babl-compat.h"
+#include "gegl/gimp-gegl-apply-operation.h"
+#include "gegl/gimp-gegl-nodes.h"
+#include "gegl/gimp-gegl-utils.h"
+
+#include "vectors/gimpvectors.h"
+
+#include "gimp.h"
+#include "gimpcontext.h"
+#include "gimperror.h"
+#include "gimpgrouplayer.h"
+#include "gimpimage.h"
+#include "gimpimage-merge.h"
+#include "gimpimage-undo.h"
+#include "gimpitemstack.h"
+#include "gimplayer-floating-selection.h"
+#include "gimplayer-new.h"
+#include "gimplayermask.h"
+#include "gimpmarshal.h"
+#include "gimpparasitelist.h"
+#include "gimppickable.h"
+#include "gimpprogress.h"
+#include "gimpprojectable.h"
+#include "gimpundostack.h"
+
+#include "gimp-intl.h"
+
+
+static GimpLayer * gimp_image_merge_layers (GimpImage     *image,
+                                            GimpContainer *container,
+                                            GSList        *merge_list,
+                                            GimpContext   *context,
+                                            GimpMergeType  merge_type,
+                                            const gchar   *undo_desc,
+                                            GimpProgress  *progress);
+
+
+/*  public functions  */
+
+GimpLayer *
+gimp_image_merge_visible_layers (GimpImage     *image,
+                                 GimpContext   *context,
+                                 GimpMergeType  merge_type,
+                                 gboolean       merge_active_group,
+                                 gboolean       discard_invisible,
+                                 GimpProgress  *progress)
+{
+  GimpContainer *container;
+  GList         *list;
+  GSList        *merge_list     = NULL;
+  GSList        *invisible_list = NULL;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+  g_return_val_if_fail (progress == NULL || GIMP_IS_PROGRESS (progress), NULL);
+
+  if (merge_active_group)
+    {
+      GimpLayer *active_layer = gimp_image_get_active_layer (image);
+
+      /*  if the active layer is the floating selection, get the
+       *  underlying drawable, but only if it is a layer
+       */
+      if (active_layer && gimp_layer_is_floating_sel (active_layer))
+        {
+          GimpDrawable *fs_drawable;
+
+          fs_drawable = gimp_layer_get_floating_sel_drawable (active_layer);
+
+          if (GIMP_IS_LAYER (fs_drawable))
+            active_layer = GIMP_LAYER (fs_drawable);
+        }
+
+      if (active_layer)
+        container = gimp_item_get_container (GIMP_ITEM (active_layer));
+      else
+        container = gimp_image_get_layers (image);
+    }
+  else
+    {
+      container = gimp_image_get_layers (image);
+    }
+
+  for (list = gimp_item_stack_get_item_iter (GIMP_ITEM_STACK (container));
+       list;
+       list = g_list_next (list))
+    {
+      GimpLayer *layer = list->data;
+
+      if (gimp_layer_is_floating_sel (layer))
+        continue;
+
+      if (gimp_item_get_visible (GIMP_ITEM (layer)))
+        {
+          merge_list = g_slist_append (merge_list, layer);
+        }
+      else if (discard_invisible)
+        {
+          invisible_list = g_slist_append (invisible_list, layer);
+        }
+    }
+
+  if (merge_list)
+    {
+      GimpLayer   *layer;
+      const gchar *undo_desc = C_("undo-type", "Merge Visible Layers");
+
+      gimp_set_busy (image->gimp);
+
+      gimp_image_undo_group_start (image,
+                                   GIMP_UNDO_GROUP_IMAGE_LAYERS_MERGE,
+                                   undo_desc);
+
+      /* if there's a floating selection, anchor it */
+      if (gimp_image_get_floating_selection (image))
+        floating_sel_anchor (gimp_image_get_floating_selection (image));
+
+      layer = gimp_image_merge_layers (image,
+                                       container,
+                                       merge_list, context, merge_type,
+                                       undo_desc, progress);
+      g_slist_free (merge_list);
+
+      if (invisible_list)
+        {
+          GSList *list;
+
+          for (list = invisible_list; list; list = g_slist_next (list))
+            gimp_image_remove_layer (image, list->data, TRUE, NULL);
+
+          g_slist_free (invisible_list);
+        }
+
+      gimp_image_undo_group_end (image);
+
+      gimp_unset_busy (image->gimp);
+
+      return layer;
+    }
+
+  return gimp_image_get_active_layer (image);
+}
+
+GimpLayer *
+gimp_image_flatten (GimpImage     *image,
+                    GimpContext   *context,
+                    GimpProgress  *progress,
+                    GError       **error)
+{
+  GList     *list;
+  GSList    *merge_list = NULL;
+  GimpLayer *layer;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+  g_return_val_if_fail (progress == NULL || GIMP_IS_PROGRESS (progress), NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, NULL);
+
+  for (list = gimp_image_get_layer_iter (image);
+       list;
+       list = g_list_next (list))
+    {
+      layer = list->data;
+
+      if (gimp_layer_is_floating_sel (layer))
+        continue;
+
+      if (gimp_item_get_visible (GIMP_ITEM (layer)))
+        merge_list = g_slist_append (merge_list, layer);
+    }
+
+  if (merge_list)
+    {
+      const gchar *undo_desc = C_("undo-type", "Flatten Image");
+
+      gimp_set_busy (image->gimp);
+
+      gimp_image_undo_group_start (image,
+                                   GIMP_UNDO_GROUP_IMAGE_LAYERS_MERGE,
+                                   undo_desc);
+
+      /* if there's a floating selection, anchor it */
+      if (gimp_image_get_floating_selection (image))
+        floating_sel_anchor (gimp_image_get_floating_selection (image));
+
+      layer = gimp_image_merge_layers (image,
+                                       gimp_image_get_layers (image),
+                                       merge_list, context,
+                                       GIMP_FLATTEN_IMAGE,
+                                       undo_desc, progress);
+      g_slist_free (merge_list);
+
+      gimp_image_alpha_changed (image);
+
+      gimp_image_undo_group_end (image);
+
+      gimp_unset_busy (image->gimp);
+
+      return layer;
+    }
+
+  g_set_error_literal (error, GIMP_ERROR, GIMP_FAILED,
+                       _("Cannot flatten an image without any visible layer."));
+  return NULL;
+}
+
+GimpLayer *
+gimp_image_merge_down (GimpImage      *image,
+                       GimpLayer      *current_layer,
+                       GimpContext    *context,
+                       GimpMergeType   merge_type,
+                       GimpProgress   *progress,
+                       GError        **error)
+{
+  GimpLayer   *layer;
+  GList       *list;
+  GList       *layer_list = NULL;
+  GSList      *merge_list = NULL;
+  const gchar *undo_desc;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_LAYER (current_layer), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (current_layer)), NULL);
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+  g_return_val_if_fail (progress == NULL || GIMP_IS_PROGRESS (progress), NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, NULL);
+
+  if (gimp_layer_is_floating_sel (current_layer))
+    {
+      g_set_error_literal (error, GIMP_ERROR, GIMP_FAILED,
+                           _("Cannot merge down a floating selection."));
+      return NULL;
+    }
+
+  if (! gimp_item_get_visible (GIMP_ITEM (current_layer)))
+    {
+      g_set_error_literal (error, GIMP_ERROR, GIMP_FAILED,
+                           _("Cannot merge down an invisible layer."));
+      return NULL;
+    }
+
+  for (list = gimp_item_get_container_iter (GIMP_ITEM (current_layer));
+       list;
+       list = g_list_next (list))
+    {
+      layer = list->data;
+
+      if (layer == current_layer)
+        break;
+    }
+
+  for (layer_list = g_list_next (list);
+       layer_list;
+       layer_list = g_list_next (layer_list))
+    {
+      layer = layer_list->data;
+
+      if (gimp_item_get_visible (GIMP_ITEM (layer)))
+        {
+          if (gimp_viewable_get_children (GIMP_VIEWABLE (layer)))
+            {
+              g_set_error_literal (error, GIMP_ERROR, GIMP_FAILED,
+                                   _("Cannot merge down to a layer group."));
+              return NULL;
+            }
+
+          if (gimp_item_is_content_locked (GIMP_ITEM (layer)))
+            {
+              g_set_error_literal (error, GIMP_ERROR, GIMP_FAILED,
+                                   _("The layer to merge down to is locked."));
+              return NULL;
+            }
+
+          merge_list = g_slist_append (NULL, layer);
+          break;
+        }
+    }
+
+  if (! merge_list)
+    {
+      g_set_error_literal (error, GIMP_ERROR, GIMP_FAILED,
+                           _("There is no visible layer to merge down to."));
+      return NULL;
+    }
+
+  merge_list = g_slist_prepend (merge_list, current_layer);
+
+  undo_desc = C_("undo-type", "Merge Down");
+
+  gimp_set_busy (image->gimp);
+
+  gimp_image_undo_group_start (image,
+                               GIMP_UNDO_GROUP_IMAGE_LAYERS_MERGE,
+                               undo_desc);
+
+  layer = gimp_image_merge_layers (image,
+                                   gimp_item_get_container (GIMP_ITEM (current_layer)),
+                                   merge_list, context, merge_type,
+                                   undo_desc, progress);
+  g_slist_free (merge_list);
+
+  gimp_image_undo_group_end (image);
+
+  gimp_unset_busy (image->gimp);
+
+  return layer;
+}
+
+GimpLayer *
+gimp_image_merge_group_layer (GimpImage      *image,
+                              GimpGroupLayer *group)
+{
+  GimpLayer *parent;
+  GimpLayer *layer;
+  gint       index;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_GROUP_LAYER (group), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (group)), NULL);
+  g_return_val_if_fail (gimp_item_get_image (GIMP_ITEM (group)) == image, NULL);
+
+  gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_IMAGE_LAYERS_MERGE,
+                               C_("undo-type", "Merge Layer Group"));
+
+  parent = gimp_layer_get_parent (GIMP_LAYER (group));
+  index  = gimp_item_get_index (GIMP_ITEM (group));
+
+  /* if this is a pass-through group, change its mode to NORMAL *before*
+   * duplicating it, since PASS_THROUGH mode is invalid for regular layers.
+   * see bug #793714.
+   */
+  if (gimp_layer_get_mode (GIMP_LAYER (group)) == GIMP_LAYER_MODE_PASS_THROUGH)
+    {
+      GimpLayerColorSpace    blend_space;
+      GimpLayerColorSpace    composite_space;
+      GimpLayerCompositeMode composite_mode;
+
+      /* keep the group's current blend space, composite space, and composite
+       * mode.
+       */
+      blend_space     = gimp_layer_get_blend_space     (GIMP_LAYER (group));
+      composite_space = gimp_layer_get_composite_space (GIMP_LAYER (group));
+      composite_mode  = gimp_layer_get_composite_mode  (GIMP_LAYER (group));
+
+      gimp_layer_set_mode            (GIMP_LAYER (group), GIMP_LAYER_MODE_NORMAL, TRUE);
+      gimp_layer_set_blend_space     (GIMP_LAYER (group), blend_space,            TRUE);
+      gimp_layer_set_composite_space (GIMP_LAYER (group), composite_space,        TRUE);
+      gimp_layer_set_composite_mode  (GIMP_LAYER (group), composite_mode,         TRUE);
+    }
+
+  layer = GIMP_LAYER (gimp_item_duplicate (GIMP_ITEM (group),
+                                           GIMP_TYPE_LAYER));
+
+  gimp_object_set_name (GIMP_OBJECT (layer), gimp_object_get_name (group));
+
+  gimp_image_remove_layer (image, GIMP_LAYER (group), TRUE, NULL);
+  gimp_image_add_layer (image, layer, parent, index, TRUE);
+
+  gimp_image_undo_group_end (image);
+
+  return layer;
+}
+
+
+/* merging vectors */
+
+GimpVectors *
+gimp_image_merge_visible_vectors (GimpImage  *image,
+                                  GError    **error)
+{
+  GList       *list;
+  GList       *merge_list = NULL;
+  GimpVectors *vectors;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, NULL);
+
+  for (list = gimp_image_get_vectors_iter (image);
+       list;
+       list = g_list_next (list))
+    {
+      vectors = list->data;
+
+      if (gimp_item_get_visible (GIMP_ITEM (vectors)))
+        merge_list = g_list_prepend (merge_list, vectors);
+    }
+
+  merge_list = g_list_reverse (merge_list);
+
+  if (merge_list && merge_list->next)
+    {
+      GimpVectors *target_vectors;
+      gchar       *name;
+      gint         pos;
+
+      gimp_set_busy (image->gimp);
+
+      gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_IMAGE_VECTORS_MERGE,
+                                   C_("undo-type", "Merge Visible Paths"));
+
+      vectors = GIMP_VECTORS (merge_list->data);
+
+      name = g_strdup (gimp_object_get_name (vectors));
+      pos = gimp_item_get_index (GIMP_ITEM (vectors));
+
+      target_vectors = GIMP_VECTORS (gimp_item_duplicate (GIMP_ITEM (vectors),
+                                                          GIMP_TYPE_VECTORS));
+      gimp_image_remove_vectors (image, vectors, TRUE, NULL);
+
+      for (list = g_list_next (merge_list);
+           list;
+           list = g_list_next (list))
+        {
+          vectors = list->data;
+
+          gimp_vectors_add_strokes (vectors, target_vectors);
+          gimp_image_remove_vectors (image, vectors, TRUE, NULL);
+        }
+
+      gimp_object_take_name (GIMP_OBJECT (target_vectors), name);
+
+      g_list_free (merge_list);
+
+      /* FIXME tree */
+      gimp_image_add_vectors (image, target_vectors, NULL, pos, TRUE);
+      gimp_unset_busy (image->gimp);
+
+      gimp_image_undo_group_end (image);
+
+      return target_vectors;
+    }
+  else
+    {
+      g_set_error_literal (error, GIMP_ERROR, GIMP_FAILED,
+                           _("Not enough visible paths for a merge. "
+                             "There must be at least two."));
+      return NULL;
+    }
+}
+
+
+/*  private functions  */
+
+static GimpLayer *
+gimp_image_merge_layers (GimpImage     *image,
+                         GimpContainer *container,
+                         GSList        *merge_list,
+                         GimpContext   *context,
+                         GimpMergeType  merge_type,
+                         const gchar   *undo_desc,
+                         GimpProgress  *progress)
+{
+  GimpLayer        *parent;
+  gint              x1, y1;
+  gint              x2, y2;
+  GSList           *layers;
+  GimpLayer        *layer;
+  GimpLayer        *top_layer;
+  GimpLayer        *bottom_layer;
+  GimpLayer        *merge_layer;
+  gint              position;
+  GeglNode         *node;
+  GeglNode         *source_node;
+  GeglNode         *flatten_node;
+  GeglNode         *offset_node;
+  GeglNode         *last_node;
+  GeglNode         *last_node_source;
+  GimpParasiteList *parasites;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+  g_return_val_if_fail (progress == NULL || GIMP_IS_PROGRESS (progress), NULL);
+
+  top_layer = merge_list->data;
+  parent    = gimp_layer_get_parent (top_layer);
+
+  /*  Make sure the image's graph is constructed, so that top-level layers have
+   *  a parent node.
+   */
+  (void) gimp_projectable_get_graph (GIMP_PROJECTABLE (image));
+
+  /*  Make sure the parent's graph is constructed, so that the top layer has a
+   *  parent node, even if it is the child of a group layer (in particular, of
+   *  an invisible group layer, whose graph may not have been constructed as a
+   *  result of the above call.  see issue #2095.)
+   */
+  if (parent)
+    (void) gimp_filter_get_node (GIMP_FILTER (parent));
+
+  /*  Build our graph inside the top-layer's parent node  */
+  source_node = gimp_filter_get_node (GIMP_FILTER (top_layer));
+  node = gegl_node_get_parent (source_node);
+
+  g_return_val_if_fail (node, NULL);
+
+  /*  Get the layer extents  */
+  x1 = y1 = 0;
+  x2 = y2 = 0;
+  for (layers = merge_list; layers; layers = g_slist_next (layers))
+    {
+      gint off_x, off_y;
+
+      layer = layers->data;
+
+      gimp_item_get_offset (GIMP_ITEM (layer), &off_x, &off_y);
+
+      switch (merge_type)
+        {
+        case GIMP_EXPAND_AS_NECESSARY:
+        case GIMP_CLIP_TO_IMAGE:
+          if (layers == merge_list)
+            {
+              x1 = off_x;
+              y1 = off_y;
+              x2 = off_x + gimp_item_get_width  (GIMP_ITEM (layer));
+              y2 = off_y + gimp_item_get_height (GIMP_ITEM (layer));
+            }
+          else
+            {
+              if (off_x < x1)
+                x1 = off_x;
+              if (off_y < y1)
+                y1 = off_y;
+              if ((off_x + gimp_item_get_width (GIMP_ITEM (layer))) > x2)
+                x2 = (off_x + gimp_item_get_width (GIMP_ITEM (layer)));
+              if ((off_y + gimp_item_get_height (GIMP_ITEM (layer))) > y2)
+                y2 = (off_y + gimp_item_get_height (GIMP_ITEM (layer)));
+            }
+
+          if (merge_type == GIMP_CLIP_TO_IMAGE)
+            {
+              x1 = CLAMP (x1, 0, gimp_image_get_width  (image));
+              y1 = CLAMP (y1, 0, gimp_image_get_height (image));
+              x2 = CLAMP (x2, 0, gimp_image_get_width  (image));
+              y2 = CLAMP (y2, 0, gimp_image_get_height (image));
+            }
+          break;
+
+        case GIMP_CLIP_TO_BOTTOM_LAYER:
+          if (layers->next == NULL)
+            {
+              x1 = off_x;
+              y1 = off_y;
+              x2 = off_x + gimp_item_get_width  (GIMP_ITEM (layer));
+              y2 = off_y + gimp_item_get_height (GIMP_ITEM (layer));
+            }
+          break;
+
+        case GIMP_FLATTEN_IMAGE:
+          if (layers->next == NULL)
+            {
+              x1 = 0;
+              y1 = 0;
+              x2 = gimp_image_get_width  (image);
+              y2 = gimp_image_get_height (image);
+            }
+          break;
+        }
+    }
+
+  if ((x2 - x1) == 0 || (y2 - y1) == 0)
+    return NULL;
+
+  bottom_layer = layer;
+
+  flatten_node = NULL;
+
+  if (merge_type == GIMP_FLATTEN_IMAGE ||
+      (gimp_drawable_is_indexed (GIMP_DRAWABLE (layer)) &&
+       ! gimp_drawable_has_alpha (GIMP_DRAWABLE (layer))))
+    {
+      GimpRGB bg;
+
+      merge_layer = gimp_layer_new (image, (x2 - x1), (y2 - y1),
+                                    gimp_image_get_layer_format (image, FALSE),
+                                    gimp_object_get_name (bottom_layer),
+                                    GIMP_OPACITY_OPAQUE,
+                                    gimp_image_get_default_new_layer_mode (image));
+
+      if (! merge_layer)
+        {
+          g_warning ("%s: could not allocate merge layer", G_STRFUNC);
+
+          return NULL;
+        }
+
+      /*  get the background for compositing  */
+      gimp_context_get_background (context, &bg);
+      gimp_pickable_srgb_to_image_color (GIMP_PICKABLE (layer),
+                                         &bg, &bg);
+
+      flatten_node = gimp_gegl_create_flatten_node (
+        &bg, gimp_layer_get_real_composite_space (bottom_layer));
+    }
+  else
+    {
+      /*  The final merged layer inherits the name of the bottom most layer
+       *  and the resulting layer has an alpha channel whether or not the
+       *  original did. Opacity is set to 100% and the MODE is set to normal.
+       */
+
+      merge_layer =
+        gimp_layer_new (image, (x2 - x1), (y2 - y1),
+                        gimp_drawable_get_format_with_alpha (GIMP_DRAWABLE (bottom_layer)),
+                        gimp_object_get_name (bottom_layer),
+                        GIMP_OPACITY_OPAQUE,
+                        gimp_image_get_default_new_layer_mode (image));
+
+      if (! merge_layer)
+        {
+          g_warning ("%s: could not allocate merge layer", G_STRFUNC);
+
+          return NULL;
+        }
+    }
+
+  if (merge_type == GIMP_FLATTEN_IMAGE)
+    {
+      position = 0;
+    }
+  else
+    {
+      /*  Find the index in the layer list of the bottom layer--we need this
+       *  in order to add the final, merged layer to the layer list correctly
+       */
+      position =
+        gimp_container_get_n_children (container) -
+        gimp_container_get_child_index (container, GIMP_OBJECT (bottom_layer));
+    }
+
+  gimp_item_set_offset (GIMP_ITEM (merge_layer), x1, y1);
+
+  offset_node = gegl_node_new_child (node,
+                                     "operation", "gegl:translate",
+                                     "x",         (gdouble) -x1,
+                                     "y",         (gdouble) -y1,
+                                     NULL);
+
+  if (flatten_node)
+    {
+      gegl_node_add_child (node, flatten_node);
+      g_object_unref (flatten_node);
+
+      gegl_node_link_many (source_node, flatten_node, offset_node, NULL);
+    }
+  else
+    {
+      gegl_node_link_many (source_node, offset_node, NULL);
+    }
+
+  /*  Disconnect the bottom-layer node's input  */
+  last_node        = gimp_filter_get_node (GIMP_FILTER (bottom_layer));
+  last_node_source = gegl_node_get_producer (last_node, "input", NULL);
+
+  gegl_node_disconnect (last_node, "input");
+
+  /*  Render the graph into the merge layer  */
+  gimp_gegl_apply_operation (NULL, progress, undo_desc, offset_node,
+                             gimp_drawable_get_buffer (
+                               GIMP_DRAWABLE (merge_layer)),
+                             NULL, FALSE);
+
+  /*  Reconnect the bottom-layer node's input  */
+  if (last_node_source)
+    gegl_node_link (last_node_source, last_node);
+
+  /*  Clean up the graph  */
+  gegl_node_remove_child (node, offset_node);
+
+  if (flatten_node)
+    gegl_node_remove_child (node, flatten_node);
+
+  /* Copy the tattoo and parasites of the bottom layer to the new layer */
+  gimp_item_set_tattoo (GIMP_ITEM (merge_layer),
+                        gimp_item_get_tattoo (GIMP_ITEM (bottom_layer)));
+
+  parasites = gimp_item_get_parasites (GIMP_ITEM (bottom_layer));
+  parasites = gimp_parasite_list_copy (parasites);
+  gimp_item_set_parasites (GIMP_ITEM (merge_layer), parasites);
+  g_object_unref (parasites);
+
+  /*  Remove the merged layers from the image  */
+  for (layers = merge_list; layers; layers = g_slist_next (layers))
+    gimp_image_remove_layer (image, layers->data, TRUE, NULL);
+
+  gimp_item_set_visible (GIMP_ITEM (merge_layer), TRUE, FALSE);
+
+  /*  if the type is flatten, remove all the remaining layers  */
+  if (merge_type == GIMP_FLATTEN_IMAGE)
+    {
+      GList *list = gimp_image_get_layer_iter (image);
+
+      while (list)
+        {
+          layer = list->data;
+
+          list = g_list_next (list);
+          gimp_image_remove_layer (image, layer, TRUE, NULL);
+        }
+
+      gimp_image_add_layer (image, merge_layer, parent,
+                            position, TRUE);
+    }
+  else
+    {
+      /*  Add the layer to the image  */
+      gimp_image_add_layer (image, merge_layer, parent,
+                            gimp_container_get_n_children (container) -
+                            position + 1,
+                            TRUE);
+    }
+
+  gimp_drawable_update (GIMP_DRAWABLE (merge_layer), 0, 0, -1, -1);
+
+  return merge_layer;
+}
diff --git a/app/core/gimpimage-merge.h b/app/core/gimpimage-merge.h
new file mode 100644
index 0000000..93aab4e
--- /dev/null
+++ b/app/core/gimpimage-merge.h
@@ -0,0 +1,46 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_IMAGE_MERGE_H__
+#define __GIMP_IMAGE_MERGE_H__
+
+
+GimpLayer   * gimp_image_merge_visible_layers  (GimpImage      *image,
+                                                GimpContext    *context,
+                                                GimpMergeType   merge_type,
+                                                gboolean        merge_active_group,
+                                                gboolean        discard_invisible,
+                                                GimpProgress   *progress);
+GimpLayer   * gimp_image_merge_down            (GimpImage      *image,
+                                                GimpLayer      *current_layer,
+                                                GimpContext    *context,
+                                                GimpMergeType   merge_type,
+                                                GimpProgress   *progress,
+                                                GError        **error);
+GimpLayer   * gimp_image_merge_group_layer     (GimpImage      *image,
+                                                GimpGroupLayer *group);
+
+GimpLayer   * gimp_image_flatten               (GimpImage      *image,
+                                                GimpContext    *context,
+                                                GimpProgress   *progress,
+                                                GError        **error);
+
+GimpVectors * gimp_image_merge_visible_vectors (GimpImage      *image,
+                                                GError        **error);
+
+
+#endif /* __GIMP_IMAGE_MERGE_H__ */
diff --git a/app/core/gimpimage-metadata.c b/app/core/gimpimage-metadata.c
new file mode 100644
index 0000000..ae0774f
--- /dev/null
+++ b/app/core/gimpimage-metadata.c
@@ -0,0 +1,184 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <cairo.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpcolor/gimpcolor.h"
+
+#include "core-types.h"
+
+#include "gimpimage.h"
+#include "gimpimage-color-profile.h"
+#include "gimpimage-metadata.h"
+#include "gimpimage-private.h"
+#include "gimpimage-undo-push.h"
+
+
+/* public functions */
+
+
+GimpMetadata *
+gimp_image_get_metadata (GimpImage *image)
+{
+  GimpImagePrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  return private->metadata;
+}
+
+void
+gimp_image_set_metadata (GimpImage    *image,
+                         GimpMetadata *metadata,
+                         gboolean      push_undo)
+{
+  GimpImagePrivate *private;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  if (metadata != private->metadata)
+    {
+      if (push_undo)
+        gimp_image_undo_push_image_metadata (image, NULL);
+
+      g_set_object (&private->metadata, metadata);
+
+      if (private->metadata)
+        {
+          gimp_image_metadata_update_pixel_size      (image);
+          gimp_image_metadata_update_bits_per_sample (image);
+          gimp_image_metadata_update_resolution      (image);
+          gimp_image_metadata_update_colorspace      (image);
+        }
+
+      g_object_notify (G_OBJECT (image), "metadata");
+    }
+}
+
+void
+gimp_image_metadata_update_pixel_size (GimpImage *image)
+{
+  GimpMetadata *metadata;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  metadata = gimp_image_get_metadata (image);
+
+  if (metadata)
+    {
+      gimp_metadata_set_pixel_size (metadata,
+                                    gimp_image_get_width  (image),
+                                    gimp_image_get_height (image));
+    }
+}
+
+void
+gimp_image_metadata_update_bits_per_sample (GimpImage *image)
+{
+  GimpMetadata *metadata;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  metadata = gimp_image_get_metadata (image);
+
+  if (metadata)
+    {
+      switch (gimp_image_get_component_type (image))
+        {
+        case GIMP_COMPONENT_TYPE_U8:
+          gimp_metadata_set_bits_per_sample (metadata, 8);
+          break;
+
+        case GIMP_COMPONENT_TYPE_U16:
+        case GIMP_COMPONENT_TYPE_HALF:
+          gimp_metadata_set_bits_per_sample (metadata, 16);
+          break;
+
+        case GIMP_COMPONENT_TYPE_U32:
+        case GIMP_COMPONENT_TYPE_FLOAT:
+          gimp_metadata_set_bits_per_sample (metadata, 32);
+          break;
+
+        case GIMP_COMPONENT_TYPE_DOUBLE:
+          gimp_metadata_set_bits_per_sample (metadata, 64);
+          break;
+        }
+    }
+}
+
+void
+gimp_image_metadata_update_resolution (GimpImage *image)
+{
+  GimpMetadata *metadata;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  metadata = gimp_image_get_metadata (image);
+
+  if (metadata)
+    {
+      gdouble xres, yres;
+
+      gimp_image_get_resolution (image, &xres, &yres);
+      gimp_metadata_set_resolution (metadata, xres, yres,
+                                    gimp_image_get_unit (image));
+    }
+}
+
+void
+gimp_image_metadata_update_colorspace (GimpImage *image)
+{
+  GimpMetadata *metadata;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  metadata = gimp_image_get_metadata (image);
+
+  if (metadata)
+    {
+      /*  See the discussions in issue #3532 and issue #301  */
+
+      GimpColorProfile       *profile = gimp_image_get_color_profile (image);
+      GimpMetadataColorspace  space   = GIMP_METADATA_COLORSPACE_UNSPECIFIED;
+
+      if (profile)
+        {
+          static GimpColorProfile *adobe = NULL;
+
+          if (! adobe)
+            adobe = gimp_color_profile_new_rgb_adobe ();
+
+          if (gimp_color_profile_is_equal (profile, adobe))
+            space = GIMP_METADATA_COLORSPACE_ADOBERGB;
+        }
+      else
+        {
+          space = GIMP_METADATA_COLORSPACE_SRGB;
+        }
+
+      gimp_metadata_set_colorspace (metadata, space);
+    }
+}
diff --git a/app/core/gimpimage-metadata.h b/app/core/gimpimage-metadata.h
new file mode 100644
index 0000000..2a74be8
--- /dev/null
+++ b/app/core/gimpimage-metadata.h
@@ -0,0 +1,33 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_IMAGE_METADATA_H__
+#define __GIMP_IMAGE_METADATA_H__
+
+
+GimpMetadata * gimp_image_get_metadata                    (GimpImage    *image);
+void           gimp_image_set_metadata                    (GimpImage    *image,
+                                                           GimpMetadata *metadata,
+                                                           gboolean      push_undo);
+
+void           gimp_image_metadata_update_pixel_size      (GimpImage    *image);
+void           gimp_image_metadata_update_bits_per_sample (GimpImage    *image);
+void           gimp_image_metadata_update_resolution      (GimpImage    *image);
+void           gimp_image_metadata_update_colorspace      (GimpImage    *image);
+
+
+#endif /* __GIMP_IMAGE_METADATA_H__ */
diff --git a/app/core/gimpimage-new.c b/app/core/gimpimage-new.c
new file mode 100644
index 0000000..4d0fa7b
--- /dev/null
+++ b/app/core/gimpimage-new.c
@@ -0,0 +1,393 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1999 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <cairo.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpcolor/gimpcolor.h"
+#include "libgimpconfig/gimpconfig.h"
+
+#include "core-types.h"
+
+#include "config/gimpcoreconfig.h"
+
+#include "gegl/gimp-babl.h"
+
+#include "gimp.h"
+#include "gimpbuffer.h"
+#include "gimpchannel.h"
+#include "gimpcontext.h"
+#include "gimpdrawable-fill.h"
+#include "gimpimage.h"
+#include "gimpimage-color-profile.h"
+#include "gimpimage-colormap.h"
+#include "gimpimage-new.h"
+#include "gimpimage-undo.h"
+#include "gimplayer.h"
+#include "gimplayer-new.h"
+#include "gimptemplate.h"
+
+#include "gimp-intl.h"
+
+
+GimpTemplate *
+gimp_image_new_get_last_template (Gimp      *gimp,
+                                  GimpImage *image)
+{
+  GimpTemplate *template;
+
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+  g_return_val_if_fail (image == NULL || GIMP_IS_IMAGE (image), NULL);
+
+  template = gimp_template_new ("image new values");
+
+  if (image)
+    {
+      gimp_config_sync (G_OBJECT (gimp->config->default_image),
+                        G_OBJECT (template), 0);
+      gimp_template_set_from_image (template, image);
+    }
+  else
+    {
+      gimp_config_sync (G_OBJECT (gimp->image_new_last_template),
+                        G_OBJECT (template), 0);
+    }
+
+  return template;
+}
+
+void
+gimp_image_new_set_last_template (Gimp         *gimp,
+                                  GimpTemplate *template)
+{
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+  g_return_if_fail (GIMP_IS_TEMPLATE (template));
+
+  gimp_config_sync (G_OBJECT (template),
+                    G_OBJECT (gimp->image_new_last_template), 0);
+}
+
+GimpImage *
+gimp_image_new_from_template (Gimp         *gimp,
+                              GimpTemplate *template,
+                              GimpContext  *context)
+{
+  GimpImage         *image;
+  GimpLayer         *layer;
+  GimpColorProfile  *profile;
+  gint               width, height;
+  gboolean           has_alpha;
+  const gchar       *comment;
+
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+  g_return_val_if_fail (GIMP_IS_TEMPLATE (template), NULL);
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+
+  image = gimp_create_image (gimp,
+                             gimp_template_get_width (template),
+                             gimp_template_get_height (template),
+                             gimp_template_get_base_type (template),
+                             gimp_template_get_precision (template),
+                             FALSE);
+
+  gimp_image_undo_disable (image);
+
+  comment = gimp_template_get_comment (template);
+
+  if (comment)
+    {
+      GimpParasite *parasite;
+
+      parasite = gimp_parasite_new ("gimp-comment",
+                                    GIMP_PARASITE_PERSISTENT,
+                                    strlen (comment) + 1,
+                                    comment);
+      gimp_image_parasite_attach (image, parasite, FALSE);
+      gimp_parasite_free (parasite);
+    }
+
+  gimp_image_set_resolution (image,
+                             gimp_template_get_resolution_x (template),
+                             gimp_template_get_resolution_y (template));
+  gimp_image_set_unit (image, gimp_template_get_resolution_unit (template));
+
+  gimp_image_set_is_color_managed (image,
+                                   gimp_template_get_color_managed (template),
+                                   FALSE);
+  profile = gimp_template_get_color_profile (template);
+  gimp_image_set_color_profile (image, profile, NULL);
+  if (profile)
+    g_object_unref (profile);
+
+  width  = gimp_image_get_width (image);
+  height = gimp_image_get_height (image);
+
+  if (gimp_template_get_fill_type (template) == GIMP_FILL_TRANSPARENT)
+    has_alpha = TRUE;
+  else
+    has_alpha = FALSE;
+
+  layer = gimp_layer_new (image, width, height,
+                          gimp_image_get_layer_format (image, has_alpha),
+                          _("Background"),
+                          GIMP_OPACITY_OPAQUE,
+                          gimp_image_get_default_new_layer_mode (image));
+
+  gimp_drawable_fill (GIMP_DRAWABLE (layer),
+                      context, gimp_template_get_fill_type (template));
+
+  gimp_image_add_layer (image, layer, NULL, 0, FALSE);
+
+  gimp_image_undo_enable (image);
+  gimp_image_clean_all (image);
+
+  return image;
+}
+
+GimpImage *
+gimp_image_new_from_drawable (Gimp         *gimp,
+                              GimpDrawable *drawable)
+{
+  GimpItem          *item;
+  GimpImage         *image;
+  GimpImage         *new_image;
+  GimpLayer         *new_layer;
+  GType              new_type;
+  gint               off_x, off_y;
+  GimpImageBaseType  type;
+  gdouble            xres;
+  gdouble            yres;
+  GimpColorProfile  *profile;
+
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
+
+  item  = GIMP_ITEM (drawable);
+  image = gimp_item_get_image (item);
+
+  type = gimp_drawable_get_base_type (drawable);
+
+  new_image = gimp_create_image (gimp,
+                                 gimp_item_get_width  (item),
+                                 gimp_item_get_height (item),
+                                 type,
+                                 gimp_drawable_get_precision (drawable),
+                                 TRUE);
+  gimp_image_undo_disable (new_image);
+
+  if (type == GIMP_INDEXED)
+    gimp_image_set_colormap (new_image,
+                             gimp_image_get_colormap (image),
+                             gimp_image_get_colormap_size (image),
+                             FALSE);
+
+  gimp_image_get_resolution (image, &xres, &yres);
+  gimp_image_set_resolution (new_image, xres, yres);
+  gimp_image_set_unit (new_image, gimp_image_get_unit (image));
+
+  gimp_image_set_is_color_managed (new_image,
+                                   gimp_image_get_is_color_managed (image),
+                                   FALSE);
+  profile = gimp_color_managed_get_color_profile (GIMP_COLOR_MANAGED (drawable));
+  gimp_image_set_color_profile (new_image, profile, NULL);
+
+  if (GIMP_IS_LAYER (drawable))
+    new_type = G_TYPE_FROM_INSTANCE (drawable);
+  else
+    new_type = GIMP_TYPE_LAYER;
+
+  new_layer = GIMP_LAYER (gimp_item_convert (GIMP_ITEM (drawable),
+                                             new_image, new_type));
+
+  gimp_object_set_name (GIMP_OBJECT (new_layer),
+                        gimp_object_get_name (drawable));
+
+  gimp_item_get_offset (GIMP_ITEM (new_layer), &off_x, &off_y);
+  gimp_item_translate (GIMP_ITEM (new_layer), -off_x, -off_y, FALSE);
+  gimp_item_set_visible (GIMP_ITEM (new_layer), TRUE, FALSE);
+  gimp_item_set_linked (GIMP_ITEM (new_layer), FALSE, FALSE);
+  gimp_layer_set_mode (new_layer,
+                       gimp_image_get_default_new_layer_mode (new_image),
+                       FALSE);
+  gimp_layer_set_opacity (new_layer, GIMP_OPACITY_OPAQUE, FALSE);
+  if (gimp_layer_can_lock_alpha (new_layer))
+    gimp_layer_set_lock_alpha (new_layer, FALSE, FALSE);
+
+  gimp_image_add_layer (new_image, new_layer, NULL, 0, TRUE);
+
+  gimp_image_undo_enable (new_image);
+
+  return new_image;
+}
+
+GimpImage *
+gimp_image_new_from_component (Gimp            *gimp,
+                               GimpImage       *image,
+                               GimpChannelType  component)
+{
+  GimpImage   *new_image;
+  GimpChannel *channel;
+  GimpLayer   *layer;
+  const gchar *desc;
+  gdouble      xres;
+  gdouble      yres;
+
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  new_image = gimp_create_image (gimp,
+                                 gimp_image_get_width  (image),
+                                 gimp_image_get_height (image),
+                                 GIMP_GRAY,
+                                 gimp_image_get_precision (image),
+                                 TRUE);
+
+  gimp_image_undo_disable (new_image);
+
+  gimp_image_get_resolution (image, &xres, &yres);
+  gimp_image_set_resolution (new_image, xres, yres);
+  gimp_image_set_unit (new_image, gimp_image_get_unit (image));
+
+  channel = gimp_channel_new_from_component (image, component, NULL, NULL);
+
+  layer = GIMP_LAYER (gimp_item_convert (GIMP_ITEM (channel),
+                                         new_image, GIMP_TYPE_LAYER));
+  g_object_unref (channel);
+
+  gimp_enum_get_value (GIMP_TYPE_CHANNEL_TYPE, component,
+                       NULL, NULL, &desc, NULL);
+  gimp_object_take_name (GIMP_OBJECT (layer),
+                         g_strdup_printf (_("%s Channel Copy"), desc));
+
+  gimp_image_add_layer (new_image, layer, NULL, 0, TRUE);
+
+  gimp_image_undo_enable (new_image);
+
+  return new_image;
+}
+
+GimpImage *
+gimp_image_new_from_buffer (Gimp       *gimp,
+                            GimpBuffer *buffer)
+{
+  GimpImage        *image;
+  GimpLayer        *layer;
+  const Babl       *format;
+  gboolean          has_alpha;
+  gdouble           res_x;
+  gdouble           res_y;
+  GimpColorProfile *profile;
+
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+  g_return_val_if_fail (GIMP_IS_BUFFER (buffer), NULL);
+
+  format    = gimp_buffer_get_format (buffer);
+  has_alpha = babl_format_has_alpha (format);
+
+  image = gimp_create_image (gimp,
+                             gimp_buffer_get_width  (buffer),
+                             gimp_buffer_get_height (buffer),
+                             gimp_babl_format_get_base_type (format),
+                             gimp_babl_format_get_precision (format),
+                             TRUE);
+  gimp_image_undo_disable (image);
+
+  if (gimp_buffer_get_resolution (buffer, &res_x, &res_y))
+    {
+      gimp_image_set_resolution (image, res_x, res_y);
+      gimp_image_set_unit (image, gimp_buffer_get_unit (buffer));
+    }
+
+  profile = gimp_buffer_get_color_profile (buffer);
+  gimp_image_set_color_profile (image, profile, NULL);
+
+  layer = gimp_layer_new_from_buffer (buffer, image,
+                                      gimp_image_get_layer_format (image,
+                                                                   has_alpha),
+                                      _("Pasted Layer"),
+                                      GIMP_OPACITY_OPAQUE,
+                                      gimp_image_get_default_new_layer_mode (image));
+
+  gimp_image_add_layer (image, layer, NULL, 0, TRUE);
+
+  gimp_image_undo_enable (image);
+
+  return image;
+}
+
+GimpImage *
+gimp_image_new_from_pixbuf (Gimp        *gimp,
+                            GdkPixbuf   *pixbuf,
+                            const gchar *layer_name)
+{
+  GimpImage         *new_image;
+  GimpLayer         *layer;
+  GimpImageBaseType  base_type;
+  gboolean           has_alpha = FALSE;
+  guint8            *icc_data;
+  gsize              icc_len;
+
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+  g_return_val_if_fail (GDK_IS_PIXBUF (pixbuf), NULL);
+
+  switch (gdk_pixbuf_get_n_channels (pixbuf))
+    {
+    case 2: has_alpha = TRUE;
+    case 1: base_type = GIMP_GRAY;
+      break;
+
+    case 4: has_alpha = TRUE;
+    case 3: base_type = GIMP_RGB;
+      break;
+
+    default:
+      g_return_val_if_reached (NULL);
+    }
+
+  new_image = gimp_create_image (gimp,
+                                 gdk_pixbuf_get_width  (pixbuf),
+                                 gdk_pixbuf_get_height (pixbuf),
+                                 base_type,
+                                 GIMP_PRECISION_U8_GAMMA,
+                                 FALSE);
+
+  gimp_image_undo_disable (new_image);
+
+  icc_data = gimp_pixbuf_get_icc_profile (pixbuf, &icc_len);
+  if (icc_data)
+    {
+      gimp_image_set_icc_profile (new_image, icc_data, icc_len, NULL);
+      g_free (icc_data);
+    }
+
+  layer = gimp_layer_new_from_pixbuf (pixbuf, new_image,
+                                      gimp_image_get_layer_format (new_image,
+                                                                   has_alpha),
+                                      layer_name,
+                                      GIMP_OPACITY_OPAQUE,
+                                      gimp_image_get_default_new_layer_mode (new_image));
+
+  gimp_image_add_layer (new_image, layer, NULL, 0, TRUE);
+
+  gimp_image_undo_enable (new_image);
+
+  return new_image;
+}
diff --git a/app/core/gimpimage-new.h b/app/core/gimpimage-new.h
new file mode 100644
index 0000000..6efd3cc
--- /dev/null
+++ b/app/core/gimpimage-new.h
@@ -0,0 +1,42 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1999 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_IMAGE_NEW_H__
+#define __GIMP_IMAGE_NEW_H__
+
+
+GimpTemplate * gimp_image_new_get_last_template (Gimp            *gimp,
+                                                 GimpImage       *image);
+void           gimp_image_new_set_last_template (Gimp            *gimp,
+                                                 GimpTemplate    *template);
+
+GimpImage    * gimp_image_new_from_template     (Gimp            *gimp,
+                                                 GimpTemplate    *template,
+                                                 GimpContext     *context);
+GimpImage    * gimp_image_new_from_drawable     (Gimp            *gimp,
+                                                 GimpDrawable    *drawable);
+GimpImage    * gimp_image_new_from_component    (Gimp            *gimp,
+                                                 GimpImage       *image,
+                                                 GimpChannelType  component);
+GimpImage    * gimp_image_new_from_buffer       (Gimp            *gimp,
+                                                 GimpBuffer      *buffer);
+GimpImage    * gimp_image_new_from_pixbuf       (Gimp            *gimp,
+                                                 GdkPixbuf       *pixbuf,
+                                                 const gchar     *layer_name);
+
+
+#endif /* __GIMP_IMAGE_NEW__ */
diff --git a/app/core/gimpimage-pick-color.c b/app/core/gimpimage-pick-color.c
new file mode 100644
index 0000000..f8168cb
--- /dev/null
+++ b/app/core/gimpimage-pick-color.c
@@ -0,0 +1,147 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-2001 Spencer Kimball, Peter Mattis, and others
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpmath/gimpmath.h"
+
+#include "core-types.h"
+
+#include "gegl/gimp-gegl-loops.h"
+
+#include "gimpchannel.h"
+#include "gimpdrawable.h"
+#include "gimpimage.h"
+#include "gimpimage-pick-color.h"
+#include "gimplayer.h"
+#include "gimppickable.h"
+
+
+gboolean
+gimp_image_pick_color (GimpImage     *image,
+                       GimpDrawable  *drawable,
+                       gint           x,
+                       gint           y,
+                       gboolean       show_all,
+                       gboolean       sample_merged,
+                       gboolean       sample_average,
+                       gdouble        average_radius,
+                       const Babl   **sample_format,
+                       gpointer       pixel,
+                       GimpRGB       *color)
+{
+  GimpPickable *pickable;
+  gboolean      result;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+  g_return_val_if_fail (drawable == NULL || GIMP_IS_DRAWABLE (drawable), FALSE);
+  g_return_val_if_fail (drawable == NULL ||
+                        gimp_item_get_image (GIMP_ITEM (drawable)) == image,
+                        FALSE);
+
+  if (sample_merged && drawable)
+    {
+      if ((GIMP_IS_LAYER (drawable) &&
+           gimp_image_get_n_layers (image) == 1) ||
+          (GIMP_IS_CHANNEL (drawable) &&
+           gimp_image_get_n_channels (image) == 1))
+        {
+          /* Let's add a special exception when an image has only one
+           * layer. This was useful in particular for indexed image as
+           * it allows to pick the right index value even when "Sample
+           * merged" is checked. There are more possible exceptions, but
+           * we can't just take them all in considerations unless we
+           * want to make code extra-complicated).
+           * See #3041.
+           */
+          sample_merged = FALSE;
+        }
+    }
+
+  if (! sample_merged)
+    {
+      if (! drawable)
+        drawable = gimp_image_get_active_drawable (image);
+
+      if (! drawable)
+        return FALSE;
+    }
+
+  if (sample_merged)
+    {
+      if (! show_all)
+        pickable = GIMP_PICKABLE (image);
+      else
+        pickable = GIMP_PICKABLE (gimp_image_get_projection (image));
+    }
+  else
+    {
+      gint off_x, off_y;
+
+      gimp_item_get_offset (GIMP_ITEM (drawable), &off_x, &off_y);
+      x -= off_x;
+      y -= off_y;
+
+      pickable = GIMP_PICKABLE (drawable);
+    }
+
+  /* Do *not* call gimp_pickable_flush() here because it's too expensive
+   * to call it unconditionally each time e.g. the cursor view is updated.
+   * Instead, call gimp_pickable_flush() in the callers if needed.
+   */
+
+  if (sample_format)
+    *sample_format = gimp_pickable_get_format (pickable);
+
+  result = gimp_pickable_pick_color (pickable, x, y,
+                                     sample_average &&
+                                     ! (show_all && sample_merged),
+                                     average_radius,
+                                     pixel, color);
+
+  if (show_all && sample_merged)
+    {
+      const Babl *format    = babl_format ("RaGaBaA double");
+      gdouble     sample[4] = {};
+
+      if (! result)
+        memset (pixel, 0, babl_format_get_bytes_per_pixel (*sample_format));
+
+      if (sample_average)
+        {
+          GeglBuffer *buffer = gimp_pickable_get_buffer (pickable);
+          gint        radius = floor (average_radius);
+
+          gimp_gegl_average_color (buffer,
+                                   GEGL_RECTANGLE (x - radius,
+                                                   y - radius,
+                                                   2 * radius + 1,
+                                                   2 * radius + 1),
+                                   FALSE, GEGL_ABYSS_NONE, format, sample);
+        }
+
+      if (! result || sample_average)
+        gimp_pickable_pixel_to_srgb (pickable, format, sample, color);
+
+      result = TRUE;
+    }
+
+  return result;
+}
diff --git a/app/core/gimpimage-pick-color.h b/app/core/gimpimage-pick-color.h
new file mode 100644
index 0000000..1ca2947
--- /dev/null
+++ b/app/core/gimpimage-pick-color.h
@@ -0,0 +1,35 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef  __GIMP_IMAGE_PICK_COLOR_H__
+#define  __GIMP_IMAGE_PICK_COLOR_H__
+
+
+gboolean   gimp_image_pick_color (GimpImage     *image,
+                                  GimpDrawable  *drawable,
+                                  gint           x,
+                                  gint           y,
+                                  gboolean       show_all,
+                                  gboolean       sample_merged,
+                                  gboolean       sample_average,
+                                  gdouble        average_radius,
+                                  const Babl   **sample_format,
+                                  gpointer       pixel,
+                                  GimpRGB       *color);
+
+
+#endif  /* __GIMP_IMAGE_PICK_COLOR_H__ */
diff --git a/app/core/gimpimage-pick-item.c b/app/core/gimpimage-pick-item.c
new file mode 100644
index 0000000..b2257f3
--- /dev/null
+++ b/app/core/gimpimage-pick-item.c
@@ -0,0 +1,381 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpmath/gimpmath.h"
+
+#include "core-types.h"
+
+#include "gimpgrouplayer.h"
+#include "gimpguide.h"
+#include "gimpimage.h"
+#include "gimpimage-pick-item.h"
+#include "gimpimage-private.h"
+#include "gimppickable.h"
+#include "gimpsamplepoint.h"
+
+#include "text/gimptextlayer.h"
+
+#include "vectors/gimpstroke.h"
+#include "vectors/gimpvectors.h"
+
+
+GimpLayer *
+gimp_image_pick_layer (GimpImage *image,
+                       gint       x,
+                       gint       y,
+                       GimpLayer *previously_picked)
+{
+  GList *all_layers;
+  GList *list;
+  gint   off_x, off_y;
+  gint   tries = 1;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  all_layers = gimp_image_get_layer_list (image);
+
+  if (previously_picked)
+    {
+      gimp_item_get_offset (GIMP_ITEM (previously_picked), &off_x, &off_y);
+      if (gimp_pickable_get_opacity_at (GIMP_PICKABLE (previously_picked),
+                                        x - off_x, y - off_y) <= 0.25)
+        previously_picked = NULL;
+      else
+        tries++;
+    }
+
+  while (tries)
+    {
+      for (list = all_layers; list; list = g_list_next (list))
+        {
+          GimpLayer *layer = list->data;
+
+          if (previously_picked)
+            {
+              /* Take the first layer with a pixel at given coordinates
+               * after the previously picked one.
+               */
+              if (layer == previously_picked)
+                previously_picked = NULL;
+              continue;
+            }
+
+          gimp_item_get_offset (GIMP_ITEM (layer), &off_x, &off_y);
+
+          if (gimp_pickable_get_opacity_at (GIMP_PICKABLE (layer),
+                                            x - off_x, y - off_y) > 0.25)
+            {
+              g_list_free (all_layers);
+
+              return layer;
+            }
+        }
+      tries--;
+    }
+
+  g_list_free (all_layers);
+
+  return NULL;
+}
+
+GimpLayer *
+gimp_image_pick_layer_by_bounds (GimpImage *image,
+                                 gint       x,
+                                 gint       y)
+{
+  GList *all_layers;
+  GList *list;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  all_layers = gimp_image_get_layer_list (image);
+
+  for (list = all_layers; list; list = g_list_next (list))
+    {
+      GimpLayer *layer = list->data;
+
+      if (gimp_item_is_visible (GIMP_ITEM (layer)))
+        {
+          gint off_x, off_y;
+          gint width, height;
+
+          gimp_item_get_offset (GIMP_ITEM (layer), &off_x, &off_y);
+          width  = gimp_item_get_width  (GIMP_ITEM (layer));
+          height = gimp_item_get_height (GIMP_ITEM (layer));
+
+          if (x >= off_x        &&
+              y >= off_y        &&
+              x < off_x + width &&
+              y < off_y + height)
+            {
+              g_list_free (all_layers);
+
+              return layer;
+            }
+        }
+    }
+
+  g_list_free (all_layers);
+
+  return NULL;
+}
+
+GimpTextLayer *
+gimp_image_pick_text_layer (GimpImage *image,
+                            gint       x,
+                            gint       y)
+{
+  GList *all_layers;
+  GList *list;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  all_layers = gimp_image_get_layer_list (image);
+
+  for (list = all_layers; list; list = g_list_next (list))
+    {
+      GimpLayer *layer = list->data;
+      gint       off_x, off_y;
+
+      gimp_item_get_offset (GIMP_ITEM (layer), &off_x, &off_y);
+
+      if (GIMP_IS_TEXT_LAYER (layer) &&
+          x >= off_x &&
+          y >= off_y &&
+          x <  off_x + gimp_item_get_width  (GIMP_ITEM (layer)) &&
+          y <  off_y + gimp_item_get_height (GIMP_ITEM (layer)) &&
+          gimp_item_is_visible (GIMP_ITEM (layer)))
+        {
+          g_list_free (all_layers);
+
+          return GIMP_TEXT_LAYER (layer);
+        }
+      else if (gimp_pickable_get_opacity_at (GIMP_PICKABLE (layer),
+                                             x - off_x, y - off_y) > 0.25)
+        {
+          /*  a normal layer covers any possible text layers below,
+           *  bail out
+           */
+
+          break;
+        }
+    }
+
+  g_list_free (all_layers);
+
+  return NULL;
+}
+
+GimpVectors *
+gimp_image_pick_vectors (GimpImage *image,
+                         gdouble    x,
+                         gdouble    y,
+                         gdouble    epsilon_x,
+                         gdouble    epsilon_y)
+{
+  GimpVectors *ret = NULL;
+  GList       *all_vectors;
+  GList       *list;
+  gdouble      mindist = G_MAXDOUBLE;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  all_vectors = gimp_image_get_vectors_list (image);
+
+  for (list = all_vectors; list; list = g_list_next (list))
+    {
+      GimpVectors *vectors = list->data;
+
+      if (gimp_item_is_visible (GIMP_ITEM (vectors)))
+        {
+          GimpStroke *stroke = NULL;
+          GimpCoords  coords = GIMP_COORDS_DEFAULT_VALUES;
+
+          while ((stroke = gimp_vectors_stroke_get_next (vectors, stroke)))
+            {
+              gdouble dist;
+
+              coords.x = x;
+              coords.y = y;
+
+              dist = gimp_stroke_nearest_point_get (stroke, &coords, 1.0,
+                                                    NULL, NULL, NULL, NULL);
+
+              if (dist >= 0.0 &&
+                  dist <  MIN (epsilon_y, mindist))
+                {
+                  mindist = dist;
+                  ret     = vectors;
+                }
+            }
+        }
+    }
+
+  g_list_free (all_vectors);
+
+  return ret;
+}
+
+static GimpGuide *
+gimp_image_pick_guide_internal (GimpImage           *image,
+                                gdouble              x,
+                                gdouble              y,
+                                gdouble              epsilon_x,
+                                gdouble              epsilon_y,
+                                GimpOrientationType  orientation)
+{
+  GList     *list;
+  GimpGuide *ret     = NULL;
+  gdouble    mindist = G_MAXDOUBLE;
+
+  for (list = GIMP_IMAGE_GET_PRIVATE (image)->guides;
+       list;
+       list = g_list_next (list))
+    {
+      GimpGuide *guide    = list->data;
+      gint       position = gimp_guide_get_position (guide);
+      gdouble    dist;
+
+      switch (gimp_guide_get_orientation (guide))
+        {
+        case GIMP_ORIENTATION_HORIZONTAL:
+          if (orientation == GIMP_ORIENTATION_HORIZONTAL ||
+              orientation == GIMP_ORIENTATION_UNKNOWN)
+            {
+              dist = ABS (position - y);
+              if (dist < MIN (epsilon_y, mindist))
+                {
+                  mindist = dist;
+                  ret = guide;
+                }
+            }
+          break;
+
+        /* mindist always is in vertical resolution to make it comparable */
+        case GIMP_ORIENTATION_VERTICAL:
+          if (orientation == GIMP_ORIENTATION_VERTICAL ||
+              orientation == GIMP_ORIENTATION_UNKNOWN)
+            {
+              dist = ABS (position - x);
+              if (dist < MIN (epsilon_x, mindist / epsilon_y * epsilon_x))
+                {
+                  mindist = dist * epsilon_y / epsilon_x;
+                  ret = guide;
+                }
+            }
+          break;
+
+        default:
+          continue;
+        }
+    }
+
+  return ret;
+}
+
+GimpGuide *
+gimp_image_pick_guide (GimpImage *image,
+                       gdouble    x,
+                       gdouble    y,
+                       gdouble    epsilon_x,
+                       gdouble    epsilon_y)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (epsilon_x > 0 && epsilon_y > 0, NULL);
+
+  return gimp_image_pick_guide_internal (image, x, y, epsilon_x, epsilon_y,
+                                         GIMP_ORIENTATION_UNKNOWN);
+}
+
+GList *
+gimp_image_pick_guides (GimpImage *image,
+                        gdouble    x,
+                        gdouble    y,
+                        gdouble    epsilon_x,
+                        gdouble    epsilon_y)
+{
+  GimpGuide *guide;
+  GList     *result = NULL;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (epsilon_x > 0 && epsilon_y > 0, NULL);
+
+  guide = gimp_image_pick_guide_internal (image, x, y, epsilon_x, epsilon_y,
+                                          GIMP_ORIENTATION_HORIZONTAL);
+
+  if (guide)
+    result = g_list_append (result, guide);
+
+  guide = gimp_image_pick_guide_internal (image, x, y, epsilon_x, epsilon_y,
+                                          GIMP_ORIENTATION_VERTICAL);
+
+  if (guide)
+    result = g_list_append (result, guide);
+
+  return result;
+}
+
+GimpSamplePoint *
+gimp_image_pick_sample_point (GimpImage *image,
+                              gdouble    x,
+                              gdouble    y,
+                              gdouble    epsilon_x,
+                              gdouble    epsilon_y)
+{
+  GList           *list;
+  GimpSamplePoint *ret     = NULL;
+  gdouble          mindist = G_MAXDOUBLE;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (epsilon_x > 0 && epsilon_y > 0, NULL);
+
+  if (x < 0 || x >= gimp_image_get_width  (image) ||
+      y < 0 || y >= gimp_image_get_height (image))
+    {
+      return NULL;
+    }
+
+  for (list = GIMP_IMAGE_GET_PRIVATE (image)->sample_points;
+       list;
+       list = g_list_next (list))
+    {
+      GimpSamplePoint *sample_point = list->data;
+      gint             sp_x;
+      gint             sp_y;
+      gdouble          dist;
+
+      gimp_sample_point_get_position (sample_point, &sp_x, &sp_y);
+
+      if (sp_x < 0 || sp_y < 0)
+        continue;
+
+      dist = hypot ((sp_x + 0.5) - x,
+                    (sp_y + 0.5) - y);
+      if (dist < MIN (epsilon_y, mindist))
+        {
+          mindist = dist;
+          ret = sample_point;
+        }
+    }
+
+  return ret;
+}
diff --git a/app/core/gimpimage-pick-item.h b/app/core/gimpimage-pick-item.h
new file mode 100644
index 0000000..46da4ef
--- /dev/null
+++ b/app/core/gimpimage-pick-item.h
@@ -0,0 +1,57 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattisbvf
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_IMAGE_PICK_ITEM_H__
+#define __GIMP_IMAGE_PICK_ITEM_H__
+
+
+GimpLayer       * gimp_image_pick_layer           (GimpImage *image,
+                                                   gint       x,
+                                                   gint       y,
+                                                   GimpLayer *previously_picked);
+GimpLayer       * gimp_image_pick_layer_by_bounds (GimpImage *image,
+                                                   gint       x,
+                                                   gint       y);
+GimpTextLayer   * gimp_image_pick_text_layer      (GimpImage *image,
+                                                   gint       x,
+                                                   gint       y);
+
+GimpVectors     * gimp_image_pick_vectors         (GimpImage *image,
+                                                   gdouble    x,
+                                                   gdouble    y,
+                                                   gdouble    epsilon_x,
+                                                   gdouble    epsilon_y);
+
+GimpGuide       * gimp_image_pick_guide           (GimpImage *image,
+                                                   gdouble    x,
+                                                   gdouble    y,
+                                                   gdouble    epsilon_x,
+                                                   gdouble    epsilon_y);
+GList           * gimp_image_pick_guides          (GimpImage *image,
+                                                   gdouble    x,
+                                                   gdouble    y,
+                                                   gdouble    epsilon_x,
+                                                   gdouble    epsilon_y);
+
+GimpSamplePoint * gimp_image_pick_sample_point    (GimpImage *image,
+                                                   gdouble    x,
+                                                   gdouble    y,
+                                                   gdouble    epsilon_x,
+                                                   gdouble    epsilon_y);
+
+
+#endif /* __GIMP_IMAGE_PICK_ITEM_H__ */
diff --git a/app/core/gimpimage-preview.c b/app/core/gimpimage-preview.c
new file mode 100644
index 0000000..e28865e
--- /dev/null
+++ b/app/core/gimpimage-preview.c
@@ -0,0 +1,214 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <cairo.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpcolor/gimpcolor.h"
+
+#include "core-types.h"
+
+#include "gegl/gimp-babl.h"
+#include "gegl/gimp-gegl-loops.h"
+
+#include "gimpimage.h"
+#include "gimpimage-color-profile.h"
+#include "gimpimage-preview.h"
+#include "gimppickable.h"
+#include "gimpprojectable.h"
+#include "gimpprojection.h"
+#include "gimptempbuf.h"
+
+
+const Babl *
+gimp_image_get_preview_format (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  switch (gimp_image_get_base_type (image))
+    {
+    case GIMP_RGB:
+    case GIMP_GRAY:
+      return gimp_babl_format_change_component_type (
+        gimp_projectable_get_format (GIMP_PROJECTABLE (image)),
+        GIMP_COMPONENT_TYPE_U8);
+
+    case GIMP_INDEXED:
+      return babl_format ("R'G'B'A u8");
+    }
+
+  g_return_val_if_reached (NULL);
+}
+
+void
+gimp_image_get_preview_size (GimpViewable *viewable,
+                             gint          size,
+                             gboolean      is_popup,
+                             gboolean      dot_for_dot,
+                             gint         *width,
+                             gint         *height)
+{
+  GimpImage *image = GIMP_IMAGE (viewable);
+  gdouble    xres;
+  gdouble    yres;
+
+  gimp_image_get_resolution (image, &xres, &yres);
+
+  gimp_viewable_calc_preview_size (gimp_image_get_width  (image),
+                                   gimp_image_get_height (image),
+                                   size,
+                                   size,
+                                   dot_for_dot,
+                                   xres,
+                                   yres,
+                                   width,
+                                   height,
+                                   NULL);
+}
+
+gboolean
+gimp_image_get_popup_size (GimpViewable *viewable,
+                           gint          width,
+                           gint          height,
+                           gboolean      dot_for_dot,
+                           gint         *popup_width,
+                           gint         *popup_height)
+{
+  GimpImage *image = GIMP_IMAGE (viewable);
+
+  if (gimp_image_get_width  (image) > width ||
+      gimp_image_get_height (image) > height)
+    {
+      gboolean scaling_up;
+
+      gimp_viewable_calc_preview_size (gimp_image_get_width  (image),
+                                       gimp_image_get_height (image),
+                                       width  * 2,
+                                       height * 2,
+                                       dot_for_dot, 1.0, 1.0,
+                                       popup_width,
+                                       popup_height,
+                                       &scaling_up);
+
+      if (scaling_up)
+        {
+          *popup_width  = gimp_image_get_width  (image);
+          *popup_height = gimp_image_get_height (image);
+        }
+
+      return TRUE;
+    }
+
+  return FALSE;
+}
+
+GimpTempBuf *
+gimp_image_get_new_preview (GimpViewable *viewable,
+                            GimpContext  *context,
+                            gint          width,
+                            gint          height)
+{
+  GimpImage   *image = GIMP_IMAGE (viewable);
+  const Babl  *format;
+  GimpTempBuf *buf;
+  gdouble      scale_x;
+  gdouble      scale_y;
+
+  scale_x = (gdouble) width  / (gdouble) gimp_image_get_width  (image);
+  scale_y = (gdouble) height / (gdouble) gimp_image_get_height (image);
+
+  format = gimp_image_get_preview_format (image);
+
+  buf = gimp_temp_buf_new (width, height, format);
+
+  gegl_buffer_get (gimp_pickable_get_buffer (GIMP_PICKABLE (image)),
+                   GEGL_RECTANGLE (0, 0, width, height),
+                   MIN (scale_x, scale_y),
+                   gimp_temp_buf_get_format (buf),
+                   gimp_temp_buf_get_data (buf),
+                   GEGL_AUTO_ROWSTRIDE, GEGL_ABYSS_CLAMP);
+
+  return buf;
+}
+
+GdkPixbuf *
+gimp_image_get_new_pixbuf (GimpViewable *viewable,
+                           GimpContext  *context,
+                           gint          width,
+                           gint          height)
+{
+  GimpImage          *image = GIMP_IMAGE (viewable);
+  GdkPixbuf          *pixbuf;
+  gdouble             scale_x;
+  gdouble             scale_y;
+  GimpColorTransform *transform;
+
+  scale_x = (gdouble) width  / (gdouble) gimp_image_get_width  (image);
+  scale_y = (gdouble) height / (gdouble) gimp_image_get_height (image);
+
+  pixbuf = gdk_pixbuf_new (GDK_COLORSPACE_RGB, TRUE, 8,
+                           width, height);
+
+  transform = gimp_image_get_color_transform_to_srgb_u8 (image);
+
+  if (transform)
+    {
+      GimpTempBuf *temp_buf;
+      GeglBuffer  *src_buf;
+      GeglBuffer  *dest_buf;
+
+      temp_buf = gimp_temp_buf_new (width, height,
+                                    gimp_pickable_get_format (GIMP_PICKABLE (image)));
+
+      gegl_buffer_get (gimp_pickable_get_buffer (GIMP_PICKABLE (image)),
+                       GEGL_RECTANGLE (0, 0, width, height),
+                       MIN (scale_x, scale_y),
+                       gimp_temp_buf_get_format (temp_buf),
+                       gimp_temp_buf_get_data (temp_buf),
+                       GEGL_AUTO_ROWSTRIDE, GEGL_ABYSS_CLAMP);
+
+      src_buf  = gimp_temp_buf_create_buffer (temp_buf);
+      dest_buf = gimp_pixbuf_create_buffer (pixbuf);
+
+      gimp_temp_buf_unref (temp_buf);
+
+      gimp_color_transform_process_buffer (transform,
+                                           src_buf,
+                                           GEGL_RECTANGLE (0, 0,
+                                                           width, height),
+                                           dest_buf,
+                                           GEGL_RECTANGLE (0, 0, 0, 0));
+
+      g_object_unref (src_buf);
+      g_object_unref (dest_buf);
+    }
+  else
+    {
+      gegl_buffer_get (gimp_pickable_get_buffer (GIMP_PICKABLE (image)),
+                       GEGL_RECTANGLE (0, 0, width, height),
+                       MIN (scale_x, scale_y),
+                       gimp_pixbuf_get_format (pixbuf),
+                       gdk_pixbuf_get_pixels (pixbuf),
+                       gdk_pixbuf_get_rowstride (pixbuf),
+                       GEGL_ABYSS_CLAMP);
+    }
+
+  return pixbuf;
+}
diff --git a/app/core/gimpimage-preview.h b/app/core/gimpimage-preview.h
new file mode 100644
index 0000000..f8b22c0
--- /dev/null
+++ b/app/core/gimpimage-preview.h
@@ -0,0 +1,51 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_IMAGE_PREVIEW_H__
+#define __GIMP_IMAGE_PREVIEW_H__
+
+
+const Babl  * gimp_image_get_preview_format (GimpImage    *image);
+
+
+/*
+ *  virtual functions of GimpImage -- don't call directly
+ */
+
+void          gimp_image_get_preview_size   (GimpViewable *viewable,
+                                             gint          size,
+                                             gboolean      is_popup,
+                                             gboolean      dot_for_dot,
+                                             gint         *width,
+                                             gint         *height);
+gboolean      gimp_image_get_popup_size     (GimpViewable *viewable,
+                                             gint          width,
+                                             gint          height,
+                                             gboolean      dot_for_dot,
+                                             gint         *popup_width,
+                                             gint         *popup_height);
+GimpTempBuf * gimp_image_get_new_preview    (GimpViewable *viewable,
+                                             GimpContext  *context,
+                                             gint          width,
+                                             gint          height);
+GdkPixbuf   * gimp_image_get_new_pixbuf     (GimpViewable *viewable,
+                                             GimpContext  *context,
+                                             gint          width,
+                                             gint          height);
+
+
+#endif /* __GIMP_IMAGE_PREVIEW_H__ */
diff --git a/app/core/gimpimage-private.h b/app/core/gimpimage-private.h
new file mode 100644
index 0000000..77687f0
--- /dev/null
+++ b/app/core/gimpimage-private.h
@@ -0,0 +1,149 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_IMAGE_PRIVATE_H__
+#define __GIMP_IMAGE_PRIVATE_H__
+
+
+typedef struct _GimpImageFlushAccumulator GimpImageFlushAccumulator;
+
+struct _GimpImageFlushAccumulator
+{
+  gboolean alpha_changed;
+  gboolean mask_changed;
+  gboolean floating_selection_changed;
+  gboolean preview_invalidated;
+};
+
+
+struct _GimpImagePrivate
+{
+  gint               ID;                    /*  provides a unique ID         */
+
+  GimpPlugInProcedure *load_proc;           /*  procedure used for loading   */
+  GimpPlugInProcedure *save_proc;           /*  last save procedure used     */
+  GimpPlugInProcedure *export_proc;         /*  last export procedure used   */
+
+  gchar             *display_name;          /*  display basename             */
+  gchar             *display_path;          /*  display full path            */
+  gint               width;                 /*  width in pixels              */
+  gint               height;                /*  height in pixels             */
+  gdouble            xresolution;           /*  image x-res, in dpi          */
+  gdouble            yresolution;           /*  image y-res, in dpi          */
+  GimpUnit           resolution_unit;       /*  resolution unit              */
+  gboolean           resolution_set;        /*  resolution explicitly set    */
+  GimpImageBaseType  base_type;             /*  base gimp_image type         */
+  GimpPrecision      precision;             /*  image's precision            */
+  GimpLayerMode      new_layer_mode;        /*  default mode of new layers   */
+
+  gint               show_all;              /*  render full image content    */
+  GeglRectangle      bounding_box;          /*  image content bounding box   */
+  gint               bounding_box_freeze_count;
+  gboolean           bounding_box_update_pending;
+  GeglBuffer        *pickable_buffer;
+
+  guchar            *colormap;              /*  colormap (for indexed)       */
+  gint               n_colors;              /*  # of colors (for indexed)    */
+  GimpPalette       *palette;               /*  palette of colormap          */
+  const Babl        *babl_palette_rgb;      /*  palette's RGB Babl format    */
+  const Babl        *babl_palette_rgba;     /*  palette's RGBA Babl format   */
+
+  gboolean           is_color_managed;      /*  is this image color managed  */
+  GimpColorProfile  *color_profile;         /*  image's color profile        */
+  gboolean           converting;            /*  color model or profile in middle of conversion?  */
+
+  /*  Cached color transforms: from layer to sRGB u8 and double, and back    */
+  gboolean            color_transforms_created;
+  GimpColorTransform *transform_to_srgb_u8;
+  GimpColorTransform *transform_from_srgb_u8;
+  GimpColorTransform *transform_to_srgb_double;
+  GimpColorTransform *transform_from_srgb_double;
+
+  GimpMetadata      *metadata;              /*  image's metadata             */
+
+  GFile             *file;                  /*  the image's XCF file         */
+  GFile             *imported_file;         /*  the image's source file      */
+  GFile             *exported_file;         /*  the image's export file      */
+  GFile             *save_a_copy_file;      /*  the image's save-a-copy file */
+  GFile             *untitled_file;         /*  a file saying "Untitled"     */
+
+  gboolean           xcf_compression;       /*  XCF compression enabled?     */
+
+  gint               dirty;                 /*  dirty flag -- # of ops       */
+  gint64             dirty_time;            /*  time when image became dirty */
+  gint               export_dirty;          /*  'dirty' but for export       */
+
+  gint               undo_freeze_count;     /*  counts the _freeze's         */
+
+  gint               instance_count;        /*  number of instances          */
+  gint               disp_count;            /*  number of displays           */
+
+  GimpTattoo         tattoo_state;          /*  the last used tattoo         */
+
+  GimpProjection    *projection;            /*  projection layers & channels */
+  GeglNode          *graph;                 /*  GEGL projection graph        */
+  GeglNode          *visible_mask;          /*  component visibility node    */
+
+  GList             *symmetries;            /*  Painting symmetries          */
+  GimpSymmetry      *active_symmetry;       /*  Active symmetry              */
+
+  GList             *guides;                /*  guides                       */
+  GimpGrid          *grid;                  /*  grid                         */
+  GList             *sample_points;         /*  color sample points          */
+
+  /*  Layer/Channel attributes  */
+  GimpItemTree      *layers;                /*  the tree of layers           */
+  GimpItemTree      *channels;              /*  the tree of masks            */
+  GimpItemTree      *vectors;               /*  the tree of vectors          */
+  GSList            *layer_stack;           /*  the layers in MRU order      */
+
+  GQuark             layer_offset_x_handler;
+  GQuark             layer_offset_y_handler;
+  GQuark             layer_bounding_box_handler;
+  GQuark             layer_alpha_handler;
+  GQuark             channel_name_changed_handler;
+  GQuark             channel_color_changed_handler;
+
+  GimpLayer         *floating_sel;          /*  the FS layer                 */
+  GimpChannel       *selection_mask;        /*  the selection mask channel   */
+
+  GimpParasiteList  *parasites;             /*  Plug-in parasite data        */
+
+  gboolean           visible[MAX_CHANNELS]; /*  visible channels             */
+  gboolean           active[MAX_CHANNELS];  /*  active channels              */
+
+  gboolean           quick_mask_state;      /*  TRUE if quick mask is on       */
+  gboolean           quick_mask_inverted;   /*  TRUE if quick mask is inverted */
+  GimpRGB            quick_mask_color;      /*  rgba triplet of the color      */
+
+  /*  Undo apparatus  */
+  GimpUndoStack     *undo_stack;            /*  stack for undo operations    */
+  GimpUndoStack     *redo_stack;            /*  stack for redo operations    */
+  gint               group_count;           /*  nested undo groups           */
+  GimpUndoType       pushing_undo_group;    /*  undo group status flag       */
+
+  /*  Signal emission accumulator  */
+  GimpImageFlushAccumulator  flush_accum;
+};
+
+#define GIMP_IMAGE_GET_PRIVATE(image) (((GimpImage *) (image))->priv)
+
+void   gimp_image_take_mask (GimpImage   *image,
+                             GimpChannel *mask);
+
+
+#endif  /* __GIMP_IMAGE_PRIVATE_H__ */
diff --git a/app/core/gimpimage-quick-mask.c b/app/core/gimpimage-quick-mask.c
new file mode 100644
index 0000000..9473bde
--- /dev/null
+++ b/app/core/gimpimage-quick-mask.c
@@ -0,0 +1,212 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <cairo.h>
+#include <gegl.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "libgimpcolor/gimpcolor.h"
+
+#include "core-types.h"
+
+#include "gimp.h"
+#include "gimpchannel.h"
+#include "gimpimage.h"
+#include "gimpimage-private.h"
+#include "gimpimage-quick-mask.h"
+#include "gimpimage-undo.h"
+#include "gimpimage-undo-push.h"
+#include "gimplayer.h"
+#include "gimplayer-floating-selection.h"
+
+#include "gimp-intl.h"
+
+
+#define CHANNEL_WAS_ACTIVE (0x2)
+
+
+/*  public functions  */
+
+void
+gimp_image_set_quick_mask_state (GimpImage *image,
+                                 gboolean   active)
+{
+  GimpImagePrivate *private;
+  GimpChannel      *selection;
+  GimpChannel      *mask;
+  gboolean          channel_was_active;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  if (active == gimp_image_get_quick_mask_state (image))
+    return;
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  /*  Keep track of the state so that we can make the right drawable
+   *  active again when deactiviting quick mask (see bug #134371).
+   */
+  if (private->quick_mask_state)
+    channel_was_active = (private->quick_mask_state & CHANNEL_WAS_ACTIVE) != 0;
+  else
+    channel_was_active = gimp_image_get_active_channel (image) != NULL;
+
+  /*  Set private->quick_mask_state early so we can return early when
+   *  being called recursively.
+   */
+  private->quick_mask_state = (active
+                               ? TRUE | (channel_was_active ?
+                                         CHANNEL_WAS_ACTIVE : 0)
+                               : FALSE);
+
+  selection = gimp_image_get_mask (image);
+  mask      = gimp_image_get_quick_mask (image);
+
+  if (active)
+    {
+      if (! mask)
+        {
+          GimpLayer *floating_sel;
+
+          gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_IMAGE_QUICK_MASK,
+                                       C_("undo-type", "Enable Quick Mask"));
+
+          floating_sel = gimp_image_get_floating_selection (image);
+
+          if (floating_sel)
+            floating_sel_to_layer (floating_sel, NULL);
+
+          mask = GIMP_CHANNEL (gimp_item_duplicate (GIMP_ITEM (selection),
+                                                    GIMP_TYPE_CHANNEL));
+
+          if (! gimp_channel_is_empty (selection))
+            gimp_channel_clear (selection, NULL, TRUE);
+
+          gimp_channel_set_color (mask, &private->quick_mask_color, FALSE);
+          gimp_item_rename (GIMP_ITEM (mask), GIMP_IMAGE_QUICK_MASK_NAME,
+                            NULL);
+
+          if (private->quick_mask_inverted)
+            gimp_channel_invert (mask, FALSE);
+
+          gimp_image_add_channel (image, mask, NULL, 0, TRUE);
+
+          gimp_image_undo_group_end (image);
+        }
+    }
+  else
+    {
+      if (mask)
+        {
+          GimpLayer *floating_sel = gimp_image_get_floating_selection (image);
+
+          gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_IMAGE_QUICK_MASK,
+                                       C_("undo-type", "Disable Quick Mask"));
+
+          if (private->quick_mask_inverted)
+            gimp_channel_invert (mask, TRUE);
+
+          if (floating_sel &&
+              gimp_layer_get_floating_sel_drawable (floating_sel) == GIMP_DRAWABLE (mask))
+            floating_sel_anchor (floating_sel);
+
+          gimp_item_to_selection (GIMP_ITEM (mask),
+                                  GIMP_CHANNEL_OP_REPLACE,
+                                  TRUE, FALSE, 0.0, 0.0);
+          gimp_image_remove_channel (image, mask, TRUE, NULL);
+
+          if (! channel_was_active)
+            gimp_image_unset_active_channel (image);
+
+          gimp_image_undo_group_end (image);
+        }
+    }
+
+  gimp_image_quick_mask_changed (image);
+}
+
+gboolean
+gimp_image_get_quick_mask_state (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->quick_mask_state;
+}
+
+void
+gimp_image_set_quick_mask_color (GimpImage     *image,
+                                 const GimpRGB *color)
+{
+  GimpChannel *quick_mask;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (color != NULL);
+
+  GIMP_IMAGE_GET_PRIVATE (image)->quick_mask_color = *color;
+
+  quick_mask = gimp_image_get_quick_mask (image);
+  if (quick_mask)
+    gimp_channel_set_color (quick_mask, color, TRUE);
+}
+
+void
+gimp_image_get_quick_mask_color (GimpImage *image,
+                                 GimpRGB   *color)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (color != NULL);
+
+  *color = GIMP_IMAGE_GET_PRIVATE (image)->quick_mask_color;
+}
+
+GimpChannel *
+gimp_image_get_quick_mask (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  return gimp_image_get_channel_by_name (image, GIMP_IMAGE_QUICK_MASK_NAME);
+}
+
+void
+gimp_image_quick_mask_invert (GimpImage *image)
+{
+  GimpImagePrivate *private;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  if (private->quick_mask_state)
+    {
+      GimpChannel *quick_mask = gimp_image_get_quick_mask (image);
+
+      if (quick_mask)
+        gimp_channel_invert (quick_mask, TRUE);
+    }
+
+  private->quick_mask_inverted = ! private->quick_mask_inverted;
+}
+
+gboolean
+gimp_image_get_quick_mask_inverted (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->quick_mask_inverted;
+}
diff --git a/app/core/gimpimage-quick-mask.h b/app/core/gimpimage-quick-mask.h
new file mode 100644
index 0000000..0eca62e
--- /dev/null
+++ b/app/core/gimpimage-quick-mask.h
@@ -0,0 +1,43 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_IMAGE_QUICK_MASK_H__
+#define __GIMP_IMAGE_QUICK_MASK_H__
+
+
+/*  don't change this string, it's used to identify the Quick Mask
+ *  when opening files.
+ */
+#define GIMP_IMAGE_QUICK_MASK_NAME "Qmask"
+
+
+void          gimp_image_set_quick_mask_state    (GimpImage     *image,
+                                                  gboolean       active);
+gboolean      gimp_image_get_quick_mask_state    (GimpImage     *image);
+
+void          gimp_image_set_quick_mask_color    (GimpImage     *image,
+                                                  const GimpRGB *color);
+void          gimp_image_get_quick_mask_color    (GimpImage     *image,
+                                                  GimpRGB       *color);
+
+GimpChannel * gimp_image_get_quick_mask          (GimpImage     *image);
+
+void          gimp_image_quick_mask_invert       (GimpImage     *image);
+gboolean      gimp_image_get_quick_mask_inverted (GimpImage     *image);
+
+
+#endif /* __GIMP_IMAGE_QUICK_MASK_H__ */
diff --git a/app/core/gimpimage-resize.c b/app/core/gimpimage-resize.c
new file mode 100644
index 0000000..e1c46ca
--- /dev/null
+++ b/app/core/gimpimage-resize.c
@@ -0,0 +1,327 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+
+#include "core-types.h"
+
+#include "gimp.h"
+#include "gimpcontainer.h"
+#include "gimpcontext.h"
+#include "gimpguide.h"
+#include "gimpimage.h"
+#include "gimpimage-guides.h"
+#include "gimpimage-item-list.h"
+#include "gimpimage-resize.h"
+#include "gimpimage-sample-points.h"
+#include "gimpimage-undo.h"
+#include "gimpimage-undo-push.h"
+#include "gimplayer.h"
+#include "gimpobjectqueue.h"
+#include "gimpprogress.h"
+#include "gimpsamplepoint.h"
+
+#include "text/gimptextlayer.h"
+
+#include "gimp-intl.h"
+
+
+void
+gimp_image_resize (GimpImage    *image,
+                   GimpContext  *context,
+                   gint          new_width,
+                   gint          new_height,
+                   gint          offset_x,
+                   gint          offset_y,
+                   GimpProgress *progress)
+{
+  gimp_image_resize_with_layers (image, context, GIMP_FILL_TRANSPARENT,
+                                 new_width, new_height, offset_x, offset_y,
+                                 GIMP_ITEM_SET_NONE, TRUE,
+                                 progress);
+}
+
+void
+gimp_image_resize_with_layers (GimpImage    *image,
+                               GimpContext  *context,
+                               GimpFillType  fill_type,
+                               gint          new_width,
+                               gint          new_height,
+                               gint          offset_x,
+                               gint          offset_y,
+                               GimpItemSet   layer_set,
+                               gboolean      resize_text_layers,
+                               GimpProgress *progress)
+{
+  GimpObjectQueue *queue;
+  GList           *resize_layers;
+  GList           *list;
+  GimpItem        *item;
+  gint             old_width, old_height;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+  g_return_if_fail (new_width > 0 && new_height > 0);
+  g_return_if_fail (progress == NULL || GIMP_IS_PROGRESS (progress));
+
+  gimp_set_busy (image->gimp);
+
+  g_object_freeze_notify (G_OBJECT (image));
+
+  gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_IMAGE_RESIZE,
+                               C_("undo-type", "Resize Image"));
+
+  resize_layers = gimp_image_item_list_get_list (image,
+                                                 GIMP_ITEM_TYPE_LAYERS,
+                                                 layer_set);
+
+  old_width  = gimp_image_get_width  (image);
+  old_height = gimp_image_get_height (image);
+
+  /*  Push the image size to the stack  */
+  gimp_image_undo_push_image_size (image, NULL,
+                                   -offset_x, -offset_y,
+                                   new_width, new_height);
+
+  /*  Set the new width and height  */
+  g_object_set (image,
+                "width",  new_width,
+                "height", new_height,
+                NULL);
+
+  /*  Reposition all layers  */
+  for (list = gimp_image_get_layer_iter (image);
+       list;
+       list = g_list_next (list))
+    {
+      GimpItem *item = list->data;
+
+      gimp_item_translate (item, offset_x, offset_y, TRUE);
+    }
+
+  queue    = gimp_object_queue_new (progress);
+  progress = GIMP_PROGRESS (queue);
+
+  for (list = resize_layers; list; list = g_list_next (list))
+    {
+      GimpItem *item = list->data;
+
+      /*  group layers can't be resized here  */
+      if (gimp_viewable_get_children (GIMP_VIEWABLE (item)))
+        continue;
+
+      if (! resize_text_layers && gimp_item_is_text_layer (item))
+        continue;
+
+      /* note that we call gimp_item_start_move(), and not
+       * gimp_item_start_transform().  see the comment in gimp_item_resize()
+       * for more information.
+       */
+      gimp_item_start_move (item, TRUE);
+
+      gimp_object_queue_push (queue, item);
+    }
+
+  g_list_free (resize_layers);
+  
+  gimp_object_queue_push (queue, gimp_image_get_mask (image));
+  gimp_object_queue_push_container (queue, gimp_image_get_channels (image));
+  gimp_object_queue_push_container (queue, gimp_image_get_vectors (image));
+
+  /*  Resize all resize_layers, channels (including selection mask), and
+   *  vectors
+   */
+  while ((item = gimp_object_queue_pop (queue)))
+    {
+      if (GIMP_IS_LAYER (item))
+        {
+          gint old_offset_x;
+          gint old_offset_y;
+
+          gimp_item_get_offset (item, &old_offset_x, &old_offset_y);
+
+          gimp_item_resize (item, context, fill_type,
+                            new_width, new_height,
+                            old_offset_x, old_offset_y);
+
+          gimp_item_end_move (item, TRUE);
+        }
+      else
+        {
+          gimp_item_resize (item, context, GIMP_FILL_TRANSPARENT,
+                            new_width, new_height, offset_x, offset_y);
+        }
+    }
+
+  /*  Reposition or remove all guides  */
+  list = gimp_image_get_guides (image);
+
+  while (list)
+    {
+      GimpGuide *guide        = list->data;
+      gboolean   remove_guide = FALSE;
+      gint       new_position = gimp_guide_get_position (guide);
+
+      list = g_list_next (list);
+
+      switch (gimp_guide_get_orientation (guide))
+        {
+        case GIMP_ORIENTATION_HORIZONTAL:
+          new_position += offset_y;
+          if (new_position < 0 || new_position > new_height)
+            remove_guide = TRUE;
+          break;
+
+        case GIMP_ORIENTATION_VERTICAL:
+          new_position += offset_x;
+          if (new_position < 0 || new_position > new_width)
+            remove_guide = TRUE;
+          break;
+
+        default:
+          break;
+        }
+
+      if (remove_guide)
+        gimp_image_remove_guide (image, guide, TRUE);
+      else if (new_position != gimp_guide_get_position (guide))
+        gimp_image_move_guide (image, guide, new_position, TRUE);
+    }
+
+  /*  Reposition or remove sample points  */
+  list = gimp_image_get_sample_points (image);
+
+  while (list)
+    {
+      GimpSamplePoint *sample_point        = list->data;
+      gboolean         remove_sample_point = FALSE;
+      gint             old_x;
+      gint             old_y;
+      gint             new_x;
+      gint             new_y;
+
+      list = g_list_next (list);
+
+      gimp_sample_point_get_position (sample_point, &old_x, &old_y);
+
+      new_y = old_y + offset_y;
+      if ((new_y < 0) || (new_y >= new_height))
+        remove_sample_point = TRUE;
+
+      new_x = old_x + offset_x;
+      if ((new_x < 0) || (new_x >= new_width))
+        remove_sample_point = TRUE;
+
+      if (remove_sample_point)
+        gimp_image_remove_sample_point (image, sample_point, TRUE);
+      else if (new_x != old_x || new_y != old_y)
+        gimp_image_move_sample_point (image, sample_point,
+                                      new_x, new_y, TRUE);
+    }
+
+  g_object_unref (queue);
+
+  gimp_image_undo_group_end (image);
+
+  gimp_image_size_changed_detailed (image,
+                                    offset_x, offset_y,
+                                    old_width, old_height);
+
+  g_object_thaw_notify (G_OBJECT (image));
+
+  gimp_unset_busy (image->gimp);
+}
+
+void
+gimp_image_resize_to_layers (GimpImage    *image,
+                             GimpContext  *context,
+                             gint         *offset_x,
+                             gint         *offset_y,
+                             gint         *new_width,
+                             gint         *new_height,
+                             GimpProgress *progress)
+{
+  GList    *list;
+  GimpItem *item;
+  gint      x, y;
+  gint      width, height;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+  g_return_if_fail (progress == NULL || GIMP_IS_PROGRESS (progress));
+
+  list = gimp_image_get_layer_iter (image);
+
+  if (! list)
+    return;
+
+  /* figure out starting values */
+  item = list->data;
+
+  x      = gimp_item_get_offset_x (item);
+  y      = gimp_item_get_offset_y (item);
+  width  = gimp_item_get_width  (item);
+  height = gimp_item_get_height (item);
+
+  /*  Respect all layers  */
+  for (list = g_list_next (list); list; list = g_list_next (list))
+    {
+      item = list->data;
+
+      gimp_rectangle_union (x, y,
+                            width, height,
+                            gimp_item_get_offset_x (item),
+                            gimp_item_get_offset_y (item),
+                            gimp_item_get_width  (item),
+                            gimp_item_get_height (item),
+                            &x, &y,
+                            &width, &height);
+    }
+
+  gimp_image_resize (image, context,
+                     width, height, -x, -y,
+                     progress);
+  if (offset_x)
+    *offset_x = -x;
+  if (offset_y)
+    *offset_y = -y;
+  if (new_width)
+    *new_width = width;
+  if (new_height)
+    *new_height = height;
+}
+
+void
+gimp_image_resize_to_selection (GimpImage    *image,
+                                GimpContext  *context,
+                                GimpProgress *progress)
+{
+  GimpChannel *selection = gimp_image_get_mask (image);
+  gint         x, y, w, h;
+
+  if (gimp_item_bounds (GIMP_ITEM (selection), &x, &y, &w, &h))
+    {
+      gimp_image_resize (image, context,
+                         w, h, -x, -y,
+                         progress);
+    }
+}
diff --git a/app/core/gimpimage-resize.h b/app/core/gimpimage-resize.h
new file mode 100644
index 0000000..edcc64c
--- /dev/null
+++ b/app/core/gimpimage-resize.h
@@ -0,0 +1,53 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattisbvf
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_IMAGE_RESIZE_H__
+#define __GIMP_IMAGE_RESIZE_H__
+
+
+void   gimp_image_resize              (GimpImage    *image,
+                                       GimpContext  *context,
+                                       gint          new_width,
+                                       gint          new_height,
+                                       gint          offset_x,
+                                       gint          offset_y,
+                                       GimpProgress *progress);
+
+void   gimp_image_resize_with_layers  (GimpImage    *image,
+                                       GimpContext  *context,
+                                       GimpFillType  fill_type,
+                                       gint          new_width,
+                                       gint          new_height,
+                                       gint          offset_x,
+                                       gint          offset_y,
+                                       GimpItemSet   layer_set,
+                                       gboolean      resize_text_layers,
+                                       GimpProgress *progress);
+
+void   gimp_image_resize_to_layers    (GimpImage    *image,
+                                       GimpContext  *context,
+                                       gint         *offset_x,
+                                       gint         *offset_y,
+                                       gint         *new_width,
+                                       gint         *new_height,
+                                       GimpProgress *progress);
+void   gimp_image_resize_to_selection (GimpImage    *image,
+                                       GimpContext  *context,
+                                       GimpProgress *progress);
+
+
+#endif /* __GIMP_IMAGE_RESIZE_H__ */
diff --git a/app/core/gimpimage-rotate.c b/app/core/gimpimage-rotate.c
new file mode 100644
index 0000000..682319f
--- /dev/null
+++ b/app/core/gimpimage-rotate.c
@@ -0,0 +1,377 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "vectors/gimpvectors.h"
+
+#include "gimp.h"
+#include "gimpcontainer.h"
+#include "gimpcontext.h"
+#include "gimpguide.h"
+#include "gimpimage.h"
+#include "gimpimage-rotate.h"
+#include "gimpimage-guides.h"
+#include "gimpimage-sample-points.h"
+#include "gimpimage-undo.h"
+#include "gimpimage-undo-push.h"
+#include "gimpitem.h"
+#include "gimplayer.h"
+#include "gimpobjectqueue.h"
+#include "gimpprogress.h"
+#include "gimpsamplepoint.h"
+
+
+static void  gimp_image_rotate_item_offset   (GimpImage        *image,
+                                              GimpRotationType  rotate_type,
+                                              GimpItem         *item,
+                                              gint              off_x,
+                                              gint              off_y);
+static void  gimp_image_rotate_guides        (GimpImage        *image,
+                                              GimpRotationType  rotate_type);
+static void  gimp_image_rotate_sample_points (GimpImage        *image,
+                                              GimpRotationType  rotate_type);
+
+
+void
+gimp_image_rotate (GimpImage        *image,
+                   GimpContext      *context,
+                   GimpRotationType  rotate_type,
+                   GimpProgress     *progress)
+{
+  GimpObjectQueue *queue;
+  GimpItem        *item;
+  GList           *list;
+  gdouble          center_x;
+  gdouble          center_y;
+  gint             new_image_width;
+  gint             new_image_height;
+  gint             previous_image_width;
+  gint             previous_image_height;
+  gint             offset_x;
+  gint             offset_y;
+  gboolean         size_changed;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+  g_return_if_fail (progress == NULL || GIMP_IS_PROGRESS (progress));
+
+  previous_image_width  = gimp_image_get_width  (image);
+  previous_image_height = gimp_image_get_height (image);
+
+  center_x              = previous_image_width  / 2.0;
+  center_y              = previous_image_height / 2.0;
+
+  /*  Resize the image (if needed)  */
+  switch (rotate_type)
+    {
+    case GIMP_ROTATE_90:
+    case GIMP_ROTATE_270:
+      new_image_width  = gimp_image_get_height (image);
+      new_image_height = gimp_image_get_width  (image);
+      size_changed     = TRUE;
+      offset_x         = (gimp_image_get_width  (image) - new_image_width)  / 2;
+      offset_y         = (gimp_image_get_height (image) - new_image_height) / 2;
+      break;
+
+    case GIMP_ROTATE_180:
+      new_image_width  = gimp_image_get_width  (image);
+      new_image_height = gimp_image_get_height (image);
+      size_changed     = FALSE;
+      offset_x         = 0;
+      offset_y         = 0;
+      break;
+
+    default:
+      g_return_if_reached ();
+      return;
+    }
+
+  gimp_set_busy (image->gimp);
+
+  queue    = gimp_object_queue_new (progress);
+  progress = GIMP_PROGRESS (queue);
+
+  gimp_object_queue_push_container (queue, gimp_image_get_layers (image));
+  gimp_object_queue_push (queue, gimp_image_get_mask (image));
+  gimp_object_queue_push_container (queue, gimp_image_get_channels (image));
+  gimp_object_queue_push_container (queue, gimp_image_get_vectors (image));
+
+  g_object_freeze_notify (G_OBJECT (image));
+
+  gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_IMAGE_ROTATE, NULL);
+
+  /*  Rotate all layers, channels (including selection mask), and vectors  */
+  while ((item = gimp_object_queue_pop (queue)))
+    {
+      gint off_x;
+      gint off_y;
+
+      gimp_item_get_offset (item, &off_x, &off_y);
+
+      gimp_item_rotate (item, context, rotate_type, center_x, center_y, FALSE);
+
+      if (GIMP_IS_LAYER (item))
+        {
+          gimp_image_rotate_item_offset (image, rotate_type, item, off_x, off_y);
+        }
+      else
+        {
+          gimp_item_set_offset (item, 0, 0);
+
+          if (GIMP_IS_VECTORS (item))
+            {
+              gimp_item_set_size (item, new_image_width, new_image_height);
+
+              gimp_item_translate (item,
+                                   (new_image_width  - gimp_image_get_width  (image)) / 2,
+                                   (new_image_height - gimp_image_get_height (image)) / 2,
+                                   FALSE);
+            }
+        }
+
+      gimp_progress_set_value (progress, 1.0);
+    }
+
+  /*  Rotate all Guides  */
+  gimp_image_rotate_guides (image, rotate_type);
+
+  /*  Rotate all sample points  */
+  gimp_image_rotate_sample_points (image, rotate_type);
+
+  /*  Resize the image (if needed)  */
+  if (size_changed)
+    {
+      gdouble xres;
+      gdouble yres;
+
+      gimp_image_undo_push_image_size (image,
+                                       NULL,
+                                       offset_x,
+                                       offset_y,
+                                       new_image_width,
+                                       new_image_height);
+
+      g_object_set (image,
+                    "width",  new_image_width,
+                    "height", new_image_height,
+                    NULL);
+
+      gimp_image_get_resolution (image, &xres, &yres);
+
+      if (xres != yres)
+        gimp_image_set_resolution (image, yres, xres);
+    }
+
+  /*  Notify guide movements  */
+  for (list = gimp_image_get_guides (image);
+       list;
+       list = g_list_next (list))
+    {
+      gimp_image_guide_moved (image, list->data);
+    }
+
+  /*  Notify sample point movements  */
+  for (list = gimp_image_get_sample_points (image);
+       list;
+       list = g_list_next (list))
+    {
+      gimp_image_sample_point_moved (image, list->data);
+    }
+
+  gimp_image_undo_group_end (image);
+
+  g_object_unref (queue);
+
+  if (size_changed)
+    gimp_image_size_changed_detailed (image,
+                                      -offset_x,
+                                      -offset_y,
+                                      previous_image_width,
+                                      previous_image_height);
+
+  g_object_thaw_notify (G_OBJECT (image));
+
+  gimp_unset_busy (image->gimp);
+}
+
+
+static void
+gimp_image_rotate_item_offset (GimpImage        *image,
+                               GimpRotationType  rotate_type,
+                               GimpItem         *item,
+                               gint              off_x,
+                               gint              off_y)
+{
+  gint x = 0;
+  gint y = 0;
+
+  switch (rotate_type)
+    {
+    case GIMP_ROTATE_90:
+      x = gimp_image_get_height (image) - off_y - gimp_item_get_width (item);
+      y = off_x;
+      break;
+
+    case GIMP_ROTATE_270:
+      x = off_y;
+      y = gimp_image_get_width (image) - off_x - gimp_item_get_height (item);
+      break;
+
+    case GIMP_ROTATE_180:
+      return;
+
+    default:
+      g_return_if_reached ();
+    }
+
+  gimp_item_get_offset (item, &off_x, &off_y);
+
+  x -= off_x;
+  y -= off_y;
+
+  if (x || y)
+    gimp_item_translate (item, x, y, FALSE);
+}
+
+static void
+gimp_image_rotate_guides (GimpImage        *image,
+                          GimpRotationType  rotate_type)
+{
+  GList *list;
+
+  /*  Rotate all Guides  */
+  for (list = gimp_image_get_guides (image);
+       list;
+       list = g_list_next (list))
+    {
+      GimpGuide           *guide       = list->data;
+      GimpOrientationType  orientation = gimp_guide_get_orientation (guide);
+      gint                 position    = gimp_guide_get_position (guide);
+
+      switch (rotate_type)
+        {
+        case GIMP_ROTATE_90:
+          switch (orientation)
+            {
+            case GIMP_ORIENTATION_HORIZONTAL:
+              gimp_image_undo_push_guide (image, NULL, guide);
+              gimp_guide_set_orientation (guide, GIMP_ORIENTATION_VERTICAL);
+              gimp_guide_set_position (guide,
+                                       gimp_image_get_height (image) - position);
+              break;
+
+            case GIMP_ORIENTATION_VERTICAL:
+              gimp_image_undo_push_guide (image, NULL, guide);
+              gimp_guide_set_orientation (guide, GIMP_ORIENTATION_HORIZONTAL);
+              break;
+
+            default:
+              break;
+            }
+          break;
+
+        case GIMP_ROTATE_180:
+          switch (orientation)
+            {
+            case GIMP_ORIENTATION_HORIZONTAL:
+              gimp_image_move_guide (image, guide,
+                                     gimp_image_get_height (image) - position,
+                                     TRUE);
+              break;
+
+            case GIMP_ORIENTATION_VERTICAL:
+              gimp_image_move_guide (image, guide,
+                                     gimp_image_get_width (image) - position,
+                                     TRUE);
+              break;
+
+            default:
+              break;
+            }
+          break;
+
+        case GIMP_ROTATE_270:
+          switch (orientation)
+            {
+            case GIMP_ORIENTATION_HORIZONTAL:
+              gimp_image_undo_push_guide (image, NULL, guide);
+              gimp_guide_set_orientation (guide, GIMP_ORIENTATION_VERTICAL);
+              break;
+
+            case GIMP_ORIENTATION_VERTICAL:
+              gimp_image_undo_push_guide (image, NULL, guide);
+              gimp_guide_set_orientation (guide, GIMP_ORIENTATION_HORIZONTAL);
+              gimp_guide_set_position (guide,
+                                       gimp_image_get_width (image) - position);
+              break;
+
+            default:
+              break;
+            }
+          break;
+        }
+    }
+}
+
+
+static void
+gimp_image_rotate_sample_points (GimpImage        *image,
+                                 GimpRotationType  rotate_type)
+{
+  GList *list;
+
+  /*  Rotate all sample points  */
+  for (list = gimp_image_get_sample_points (image);
+       list;
+       list = g_list_next (list))
+    {
+      GimpSamplePoint *sample_point = list->data;
+      gint             old_x;
+      gint             old_y;
+
+      gimp_image_undo_push_sample_point (image, NULL, sample_point);
+
+      gimp_sample_point_get_position (sample_point, &old_x, &old_y);
+
+      switch (rotate_type)
+        {
+        case GIMP_ROTATE_90:
+          gimp_sample_point_set_position (sample_point,
+                                          gimp_image_get_height (image) - old_y,
+                                          old_x);
+          break;
+
+        case GIMP_ROTATE_180:
+          gimp_sample_point_set_position (sample_point,
+                                          gimp_image_get_width  (image) - old_x,
+                                          gimp_image_get_height (image) - old_y);
+          break;
+
+        case GIMP_ROTATE_270:
+          gimp_sample_point_set_position (sample_point,
+                                          old_y,
+                                          gimp_image_get_width (image) - old_x);
+          break;
+        }
+    }
+}
diff --git a/app/core/gimpimage-rotate.h b/app/core/gimpimage-rotate.h
new file mode 100644
index 0000000..cad0de8
--- /dev/null
+++ b/app/core/gimpimage-rotate.h
@@ -0,0 +1,28 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattisbvf
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_IMAGE_ROTATE_H__
+#define __GIMP_IMAGE_ROTATE_H__
+
+
+void   gimp_image_rotate (GimpImage        *image,
+                          GimpContext      *context,
+                          GimpRotationType  rotate_type,
+                          GimpProgress     *progress);
+
+
+#endif /* __GIMP_IMAGE_ROTATE_H__ */
diff --git a/app/core/gimpimage-sample-points.c b/app/core/gimpimage-sample-points.c
new file mode 100644
index 0000000..24fc66f
--- /dev/null
+++ b/app/core/gimpimage-sample-points.c
@@ -0,0 +1,213 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gimp.h"
+#include "gimpimage.h"
+#include "gimpimage-private.h"
+#include "gimpimage-sample-points.h"
+#include "gimpimage-undo-push.h"
+#include "gimpsamplepoint.h"
+
+#include "gimp-intl.h"
+
+
+/*  public functions  */
+
+GimpSamplePoint *
+gimp_image_add_sample_point_at_pos (GimpImage *image,
+                                    gint       x,
+                                    gint       y,
+                                    gboolean   push_undo)
+{
+  GimpSamplePoint *sample_point;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (x >= 0 && x < gimp_image_get_width  (image), NULL);
+  g_return_val_if_fail (y >= 0 && y < gimp_image_get_height (image), NULL);
+
+  sample_point = gimp_sample_point_new (image->gimp->next_sample_point_ID++);
+
+  if (push_undo)
+    gimp_image_undo_push_sample_point (image, C_("undo-type", "Add Sample Point"),
+                                       sample_point);
+
+  gimp_image_add_sample_point (image, sample_point, x, y);
+  g_object_unref (sample_point);
+
+  return sample_point;
+}
+
+void
+gimp_image_add_sample_point (GimpImage       *image,
+                             GimpSamplePoint *sample_point,
+                             gint             x,
+                             gint             y)
+{
+  GimpImagePrivate *private;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (GIMP_IS_SAMPLE_POINT (sample_point));
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  private->sample_points = g_list_append (private->sample_points, sample_point);
+
+  gimp_sample_point_set_position (sample_point, x, y);
+  g_object_ref (sample_point);
+
+  gimp_image_sample_point_added (image, sample_point);
+}
+
+void
+gimp_image_remove_sample_point (GimpImage       *image,
+                                GimpSamplePoint *sample_point,
+                                gboolean         push_undo)
+{
+  GimpImagePrivate *private;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (GIMP_IS_SAMPLE_POINT (sample_point));
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  if (push_undo)
+    gimp_image_undo_push_sample_point (image,
+                                       C_("undo-type", "Remove Sample Point"),
+                                       sample_point);
+
+  private->sample_points = g_list_remove (private->sample_points, sample_point);
+  gimp_aux_item_removed (GIMP_AUX_ITEM (sample_point));
+
+  gimp_image_sample_point_removed (image, sample_point);
+
+  gimp_sample_point_set_position (sample_point,
+                                  GIMP_SAMPLE_POINT_POSITION_UNDEFINED,
+                                  GIMP_SAMPLE_POINT_POSITION_UNDEFINED);
+  g_object_unref (sample_point);
+}
+
+void
+gimp_image_move_sample_point (GimpImage       *image,
+                              GimpSamplePoint *sample_point,
+                              gint             x,
+                              gint             y,
+                              gboolean         push_undo)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (GIMP_IS_SAMPLE_POINT (sample_point));
+  g_return_if_fail (x >= 0);
+  g_return_if_fail (y >= 0);
+  g_return_if_fail (x < gimp_image_get_width  (image));
+  g_return_if_fail (y < gimp_image_get_height (image));
+
+  if (push_undo)
+    gimp_image_undo_push_sample_point (image,
+                                       C_("undo-type", "Move Sample Point"),
+                                       sample_point);
+
+  gimp_sample_point_set_position (sample_point, x, y);
+
+  gimp_image_sample_point_moved (image, sample_point);
+}
+
+void
+gimp_image_set_sample_point_pick_mode (GimpImage         *image,
+                                       GimpSamplePoint   *sample_point,
+                                       GimpColorPickMode  pick_mode,
+                                       gboolean           push_undo)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (GIMP_IS_SAMPLE_POINT (sample_point));
+
+  if (push_undo)
+    gimp_image_undo_push_sample_point (image,
+                                       C_("undo-type",
+                                          "Set Sample Point Pick Mode"),
+                                       sample_point);
+
+  gimp_sample_point_set_pick_mode (sample_point, pick_mode);
+
+  /* well... */
+  gimp_image_sample_point_moved (image, sample_point);
+}
+
+GList *
+gimp_image_get_sample_points (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->sample_points;
+}
+
+GimpSamplePoint *
+gimp_image_get_sample_point (GimpImage *image,
+                             guint32    id)
+{
+  GList *sample_points;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  for (sample_points = GIMP_IMAGE_GET_PRIVATE (image)->sample_points;
+       sample_points;
+       sample_points = g_list_next (sample_points))
+    {
+      GimpSamplePoint *sample_point = sample_points->data;
+
+      if (gimp_aux_item_get_ID (GIMP_AUX_ITEM (sample_point)) == id)
+        return sample_point;
+    }
+
+  return NULL;
+}
+
+GimpSamplePoint *
+gimp_image_get_next_sample_point (GimpImage *image,
+                                  guint32    id,
+                                  gboolean  *sample_point_found)
+{
+  GList *sample_points;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (sample_point_found != NULL, NULL);
+
+  if (id == 0)
+    *sample_point_found = TRUE;
+  else
+    *sample_point_found = FALSE;
+
+  for (sample_points = GIMP_IMAGE_GET_PRIVATE (image)->sample_points;
+       sample_points;
+       sample_points = g_list_next (sample_points))
+    {
+      GimpSamplePoint *sample_point = sample_points->data;
+
+      if (*sample_point_found) /* this is the first guide after the found one */
+        return sample_point;
+
+      if (gimp_aux_item_get_ID (GIMP_AUX_ITEM (sample_point)) == id) /* found it, next one will be returned */
+        *sample_point_found = TRUE;
+    }
+
+  return NULL;
+}
diff --git a/app/core/gimpimage-sample-points.h b/app/core/gimpimage-sample-points.h
new file mode 100644
index 0000000..c84a02b
--- /dev/null
+++ b/app/core/gimpimage-sample-points.h
@@ -0,0 +1,60 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_IMAGE_SAMPLE_POINTS_H__
+#define __GIMP_IMAGE_SAMPLE_POINTS_H__
+
+
+/*  public sample point adding API
+ */
+GimpSamplePoint * gimp_image_add_sample_point_at_pos (GimpImage        *image,
+                                                      gint              x,
+                                                      gint              y,
+                                                      gboolean          push_undo);
+
+/*  internal sample point adding API, does not check the sample
+ *  point's position and is publicly declared only to be used from
+ *  undo
+ */
+void              gimp_image_add_sample_point        (GimpImage       *image,
+                                                      GimpSamplePoint *sample_point,
+                                                      gint             x,
+                                                      gint             y);
+
+void              gimp_image_remove_sample_point     (GimpImage       *image,
+                                                      GimpSamplePoint *sample_point,
+                                                      gboolean         push_undo);
+void              gimp_image_move_sample_point       (GimpImage       *image,
+                                                      GimpSamplePoint *sample_point,
+                                                      gint             x,
+                                                      gint             y,
+                                                      gboolean         push_undo);
+void              gimp_image_set_sample_point_pick_mode
+                                                     (GimpImage       *image,
+                                                      GimpSamplePoint *sample_point,
+                                                      GimpColorPickMode pick_mode,
+                                                      gboolean         push_undo);
+
+GList           * gimp_image_get_sample_points       (GimpImage       *image);
+GimpSamplePoint * gimp_image_get_sample_point        (GimpImage       *image,
+                                                      guint32          id);
+GimpSamplePoint * gimp_image_get_next_sample_point   (GimpImage       *image,
+                                                      guint32          id,
+                                                      gboolean        *sample_point_found);
+
+
+#endif /* __GIMP_IMAGE_SAMPLE_POINTS_H__ */
diff --git a/app/core/gimpimage-scale.c b/app/core/gimpimage-scale.c
new file mode 100644
index 0000000..04ae6fb
--- /dev/null
+++ b/app/core/gimpimage-scale.c
@@ -0,0 +1,260 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gimp.h"
+#include "gimpcontainer.h"
+#include "gimpguide.h"
+#include "gimpgrouplayer.h"
+#include "gimpimage.h"
+#include "gimpimage-guides.h"
+#include "gimpimage-sample-points.h"
+#include "gimpimage-scale.h"
+#include "gimpimage-undo.h"
+#include "gimpimage-undo-push.h"
+#include "gimplayer.h"
+#include "gimpobjectqueue.h"
+#include "gimpprogress.h"
+#include "gimpprojection.h"
+#include "gimpsamplepoint.h"
+
+#include "gimp-log.h"
+#include "gimp-intl.h"
+
+
+void
+gimp_image_scale (GimpImage             *image,
+                  gint                   new_width,
+                  gint                   new_height,
+                  GimpInterpolationType  interpolation_type,
+                  GimpProgress          *progress)
+{
+  GimpObjectQueue *queue;
+  GimpItem        *item;
+  GList           *list;
+  gint             old_width;
+  gint             old_height;
+  gint             offset_x;
+  gint             offset_y;
+  gdouble          img_scale_w = 1.0;
+  gdouble          img_scale_h = 1.0;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (new_width > 0 && new_height > 0);
+  g_return_if_fail (progress == NULL || GIMP_IS_PROGRESS (progress));
+
+  gimp_set_busy (image->gimp);
+
+  queue    = gimp_object_queue_new (progress);
+  progress = GIMP_PROGRESS (queue);
+
+  gimp_object_queue_push_container (queue, gimp_image_get_layers (image));
+  gimp_object_queue_push (queue, gimp_image_get_mask (image));
+  gimp_object_queue_push_container (queue, gimp_image_get_channels (image));
+  gimp_object_queue_push_container (queue, gimp_image_get_vectors (image));
+
+  g_object_freeze_notify (G_OBJECT (image));
+
+  gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_IMAGE_SCALE,
+                               C_("undo-type", "Scale Image"));
+
+  old_width   = gimp_image_get_width  (image);
+  old_height  = gimp_image_get_height (image);
+  img_scale_w = (gdouble) new_width  / (gdouble) old_width;
+  img_scale_h = (gdouble) new_height / (gdouble) old_height;
+
+  offset_x = (old_width  - new_width)  / 2;
+  offset_y = (old_height - new_height) / 2;
+
+  /*  Push the image size to the stack  */
+  gimp_image_undo_push_image_size (image,
+                                   NULL,
+                                   offset_x,
+                                   offset_y,
+                                   new_width,
+                                   new_height);
+
+  /*  Set the new width and height early, so below image item setters
+   *  (esp. guides and sample points) don't choke about moving stuff
+   *  out of the image
+   */
+  g_object_set (image,
+                "width",  new_width,
+                "height", new_height,
+                NULL);
+
+  /*  Scale all layers, channels (including selection mask), and vectors  */
+  while ((item = gimp_object_queue_pop (queue)))
+    {
+      if (! gimp_item_scale_by_factors (item,
+                                        img_scale_w, img_scale_h,
+                                        interpolation_type, progress))
+        {
+          /* Since 0 < img_scale_w, img_scale_h, failure due to one or more
+           * vanishing scaled layer dimensions. Implicit delete implemented
+           * here. Upstream warning implemented in resize_check_layer_scaling(),
+           * which offers the user the chance to bail out.
+           */
+          g_return_if_fail (GIMP_IS_LAYER (item));
+          gimp_image_remove_layer (image, GIMP_LAYER (item), TRUE, NULL);
+        }
+    }
+
+  /*  Scale all Guides  */
+  for (list = gimp_image_get_guides (image);
+       list;
+       list = g_list_next (list))
+    {
+      GimpGuide *guide    = list->data;
+      gint       position = gimp_guide_get_position (guide);
+
+      switch (gimp_guide_get_orientation (guide))
+        {
+        case GIMP_ORIENTATION_HORIZONTAL:
+          gimp_image_move_guide (image, guide,
+                                 (position * new_height) / old_height,
+                                 TRUE);
+          break;
+
+        case GIMP_ORIENTATION_VERTICAL:
+          gimp_image_move_guide (image, guide,
+                                 (position * new_width) / old_width,
+                                 TRUE);
+          break;
+
+        default:
+          break;
+        }
+    }
+
+  /*  Scale all sample points  */
+  for (list = gimp_image_get_sample_points (image);
+       list;
+       list = g_list_next (list))
+    {
+      GimpSamplePoint *sample_point = list->data;
+      gint             x;
+      gint             y;
+
+      gimp_sample_point_get_position (sample_point, &x, &y);
+
+      gimp_image_move_sample_point (image, sample_point,
+                                    x * new_width  / old_width,
+                                    y * new_height / old_height,
+                                    TRUE);
+    }
+
+  gimp_image_undo_group_end (image);
+
+  g_object_unref (queue);
+
+  gimp_image_size_changed_detailed (image,
+                                    -offset_x,
+                                    -offset_y,
+                                    old_width,
+                                    old_height);
+
+  g_object_thaw_notify (G_OBJECT (image));
+
+  gimp_unset_busy (image->gimp);
+}
+
+/**
+ * gimp_image_scale_check:
+ * @image:      A #GimpImage.
+ * @new_width:   The new width.
+ * @new_height:  The new height.
+ * @max_memsize: The maximum new memory size.
+ * @new_memsize: The new memory size.
+ *
+ * Inventory the layer list in image and check that it may be
+ * scaled to @new_height and @new_width without problems.
+ *
+ * Return value: #GIMP_IMAGE_SCALE_OK if scaling the image will shrink none
+ *               of its layers completely away, and the new image size
+ *               is smaller than @max_memsize.
+ *               #GIMP_IMAGE_SCALE_TOO_SMALL if scaling would remove some
+ *               existing layers.
+ *               #GIMP_IMAGE_SCALE_TOO_BIG if the new image size would
+ *               exceed the maximum specified in the preferences.
+ **/
+GimpImageScaleCheckType
+gimp_image_scale_check (GimpImage *image,
+                        gint       new_width,
+                        gint       new_height,
+                        gint64     max_memsize,
+                        gint64    *new_memsize)
+{
+  GList  *all_layers;
+  GList  *list;
+  gint64  current_size;
+  gint64  undo_size;
+  gint64  redo_size;
+  gint64  new_size;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), GIMP_IMAGE_SCALE_TOO_SMALL);
+  g_return_val_if_fail (new_memsize != NULL, GIMP_IMAGE_SCALE_TOO_SMALL);
+
+  current_size = gimp_object_get_memsize (GIMP_OBJECT (image), NULL);
+
+  new_size = gimp_image_estimate_memsize (image,
+                                          gimp_image_get_component_type (image),
+                                          new_width, new_height);
+
+  undo_size = gimp_object_get_memsize (GIMP_OBJECT (gimp_image_get_undo_stack (image)), NULL);
+  redo_size = gimp_object_get_memsize (GIMP_OBJECT (gimp_image_get_redo_stack (image)), NULL);
+
+  current_size -= undo_size + redo_size;
+  new_size     -= undo_size + redo_size;
+
+  GIMP_LOG (IMAGE_SCALE,
+            "old_size = %"G_GINT64_FORMAT"  new_size = %"G_GINT64_FORMAT,
+            current_size, new_size);
+
+  *new_memsize = new_size;
+
+  if (new_size > current_size && new_size > max_memsize)
+    return GIMP_IMAGE_SCALE_TOO_BIG;
+
+  all_layers = gimp_image_get_layer_list (image);
+
+  for (list = all_layers; list; list = g_list_next (list))
+    {
+      GimpItem *item = list->data;
+
+      /*  group layers are updated automatically  */
+      if (gimp_viewable_get_children (GIMP_VIEWABLE (item)))
+        continue;
+
+      if (! gimp_item_check_scaling (item, new_width, new_height))
+        {
+          g_list_free (all_layers);
+
+          return GIMP_IMAGE_SCALE_TOO_SMALL;
+        }
+    }
+
+  g_list_free (all_layers);
+
+  return GIMP_IMAGE_SCALE_OK;
+}
diff --git a/app/core/gimpimage-scale.h b/app/core/gimpimage-scale.h
new file mode 100644
index 0000000..1073e38
--- /dev/null
+++ b/app/core/gimpimage-scale.h
@@ -0,0 +1,36 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattisbvf
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_IMAGE_SCALE_H__
+#define __GIMP_IMAGE_SCALE_H__
+
+
+void   gimp_image_scale         (GimpImage             *image,
+                                 gint                   new_width,
+                                 gint                   new_height,
+                                 GimpInterpolationType  interpolation_type,
+                                 GimpProgress          *progress);
+
+GimpImageScaleCheckType
+       gimp_image_scale_check   (GimpImage             *image,
+                                 gint                   new_width,
+                                 gint                   new_height,
+                                 gint64                 max_memsize,
+                                 gint64                *new_memsize);
+
+
+#endif /* __GIMP_IMAGE_SCALE_H__ */
diff --git a/app/core/gimpimage-snap.c b/app/core/gimpimage-snap.c
new file mode 100644
index 0000000..e35b646
--- /dev/null
+++ b/app/core/gimpimage-snap.c
@@ -0,0 +1,719 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpmath/gimpmath.h"
+
+#include "core-types.h"
+
+#include "gimp.h"
+#include "gimpgrid.h"
+#include "gimpguide.h"
+#include "gimpimage.h"
+#include "gimpimage-grid.h"
+#include "gimpimage-guides.h"
+#include "gimpimage-snap.h"
+
+#include "vectors/gimpstroke.h"
+#include "vectors/gimpvectors.h"
+
+#include "gimp-intl.h"
+
+
+static gboolean  gimp_image_snap_distance (const gdouble  unsnapped,
+                                           const gdouble  nearest,
+                                           const gdouble  epsilon,
+                                           gdouble       *mindist,
+                                           gdouble       *target);
+
+
+
+/*  public functions  */
+
+gboolean
+gimp_image_snap_x (GimpImage *image,
+                   gdouble    x,
+                   gdouble   *tx,
+                   gdouble    epsilon_x,
+                   gboolean   snap_to_guides,
+                   gboolean   snap_to_grid,
+                   gboolean   snap_to_canvas)
+{
+  gdouble   mindist = G_MAXDOUBLE;
+  gboolean  snapped = FALSE;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+  g_return_val_if_fail (tx != NULL, FALSE);
+
+  *tx = x;
+
+  if (! gimp_image_get_guides (image)) snap_to_guides = FALSE;
+  if (! gimp_image_get_grid (image))   snap_to_grid   = FALSE;
+
+  if (! (snap_to_guides || snap_to_grid || snap_to_canvas))
+    return FALSE;
+
+  if (x < -epsilon_x || x >= (gimp_image_get_width (image) + epsilon_x))
+    return FALSE;
+
+  if (snap_to_guides)
+    {
+      GList *list;
+
+      for (list = gimp_image_get_guides (image); list; list = g_list_next (list))
+        {
+          GimpGuide *guide    = list->data;
+          gint       position = gimp_guide_get_position (guide);
+
+          if (gimp_guide_is_custom (guide))
+            continue;
+
+          if (gimp_guide_get_orientation (guide) == GIMP_ORIENTATION_VERTICAL)
+            {
+              snapped |= gimp_image_snap_distance (x, position,
+                                                   epsilon_x,
+                                                   &mindist, tx);
+            }
+        }
+    }
+
+  if (snap_to_grid)
+    {
+      GimpGrid *grid = gimp_image_get_grid (image);
+      gdouble   xspacing;
+      gdouble   xoffset;
+
+      gimp_grid_get_spacing (grid, &xspacing, NULL);
+      gimp_grid_get_offset  (grid, &xoffset,  NULL);
+
+      if (xspacing > 0.0)
+        {
+          gdouble nearest;
+
+          nearest = xoffset + RINT ((x - xoffset) / xspacing) * xspacing;
+
+          snapped |= gimp_image_snap_distance (x, nearest,
+                                               epsilon_x,
+                                               &mindist, tx);
+        }
+    }
+
+  if (snap_to_canvas)
+    {
+      snapped |= gimp_image_snap_distance (x, 0,
+                                           epsilon_x,
+                                           &mindist, tx);
+      snapped |= gimp_image_snap_distance (x, gimp_image_get_width (image),
+                                           epsilon_x,
+                                           &mindist, tx);
+    }
+
+  return snapped;
+}
+
+gboolean
+gimp_image_snap_y (GimpImage *image,
+                   gdouble    y,
+                   gdouble   *ty,
+                   gdouble    epsilon_y,
+                   gboolean   snap_to_guides,
+                   gboolean   snap_to_grid,
+                   gboolean   snap_to_canvas)
+{
+  gdouble    mindist = G_MAXDOUBLE;
+  gboolean   snapped = FALSE;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+  g_return_val_if_fail (ty != NULL, FALSE);
+
+  *ty = y;
+
+  if (! gimp_image_get_guides (image)) snap_to_guides = FALSE;
+  if (! gimp_image_get_grid (image))   snap_to_grid   = FALSE;
+
+  if (! (snap_to_guides || snap_to_grid || snap_to_canvas))
+    return FALSE;
+
+  if (y < -epsilon_y || y >= (gimp_image_get_height (image) + epsilon_y))
+    return FALSE;
+
+  if (snap_to_guides)
+    {
+      GList *list;
+
+      for (list = gimp_image_get_guides (image); list; list = g_list_next (list))
+        {
+          GimpGuide *guide    = list->data;
+          gint       position = gimp_guide_get_position (guide);
+
+          if (gimp_guide_is_custom (guide))
+            continue;
+
+          if (gimp_guide_get_orientation (guide) == GIMP_ORIENTATION_HORIZONTAL)
+            {
+              snapped |= gimp_image_snap_distance (y, position,
+                                                   epsilon_y,
+                                                   &mindist, ty);
+            }
+        }
+    }
+
+  if (snap_to_grid)
+    {
+      GimpGrid *grid = gimp_image_get_grid (image);
+      gdouble   yspacing;
+      gdouble   yoffset;
+
+      gimp_grid_get_spacing (grid, NULL, &yspacing);
+      gimp_grid_get_offset  (grid, NULL, &yoffset);
+
+      if (yspacing > 0.0)
+        {
+          gdouble nearest;
+
+          nearest = yoffset + RINT ((y - yoffset) / yspacing) * yspacing;
+
+          snapped |= gimp_image_snap_distance (y, nearest,
+                                               epsilon_y,
+                                               &mindist, ty);
+        }
+    }
+
+  if (snap_to_canvas)
+    {
+      snapped |= gimp_image_snap_distance (y, 0,
+                                           epsilon_y,
+                                           &mindist, ty);
+      snapped |= gimp_image_snap_distance (y, gimp_image_get_height (image),
+                                           epsilon_y,
+                                           &mindist, ty);
+    }
+
+  return snapped;
+}
+
+gboolean
+gimp_image_snap_point (GimpImage *image,
+                       gdouble    x,
+                       gdouble    y,
+                       gdouble   *tx,
+                       gdouble   *ty,
+                       gdouble    epsilon_x,
+                       gdouble    epsilon_y,
+                       gboolean   snap_to_guides,
+                       gboolean   snap_to_grid,
+                       gboolean   snap_to_canvas,
+                       gboolean   snap_to_vectors,
+                       gboolean   show_all)
+{
+  gdouble  mindist_x = G_MAXDOUBLE;
+  gdouble  mindist_y = G_MAXDOUBLE;
+  gboolean snapped   = FALSE;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+  g_return_val_if_fail (tx != NULL, FALSE);
+  g_return_val_if_fail (ty != NULL, FALSE);
+
+  *tx = x;
+  *ty = y;
+
+  if (! gimp_image_get_guides (image))         snap_to_guides  = FALSE;
+  if (! gimp_image_get_grid (image))           snap_to_grid    = FALSE;
+  if (! gimp_image_get_active_vectors (image)) snap_to_vectors = FALSE;
+
+  if (! (snap_to_guides || snap_to_grid || snap_to_canvas || snap_to_vectors))
+    return FALSE;
+
+  if (! show_all &&
+      (x < -epsilon_x || x >= (gimp_image_get_width  (image) + epsilon_x) ||
+       y < -epsilon_y || y >= (gimp_image_get_height (image) + epsilon_y)))
+    {
+      /* Off-canvas grid is invisible unless "show all" option is
+       * enabled. So let's not snap to the invisible grid.
+       */
+      snap_to_grid   = FALSE;
+      snap_to_canvas = FALSE;
+    }
+
+  if (snap_to_guides)
+    {
+      GList *list;
+
+      for (list = gimp_image_get_guides (image); list; list = g_list_next (list))
+        {
+          GimpGuide *guide    = list->data;
+          gint       position = gimp_guide_get_position (guide);
+
+          if (gimp_guide_is_custom (guide))
+            continue;
+
+          switch (gimp_guide_get_orientation (guide))
+            {
+            case GIMP_ORIENTATION_HORIZONTAL:
+              snapped |= gimp_image_snap_distance (y, position,
+                                                   epsilon_y,
+                                                   &mindist_y, ty);
+              break;
+
+            case GIMP_ORIENTATION_VERTICAL:
+              snapped |= gimp_image_snap_distance (x, position,
+                                                   epsilon_x,
+                                                   &mindist_x, tx);
+              break;
+
+            default:
+              break;
+            }
+        }
+    }
+
+  if (snap_to_grid)
+    {
+      GimpGrid *grid = gimp_image_get_grid (image);
+      gdouble   xspacing, yspacing;
+      gdouble   xoffset, yoffset;
+
+      gimp_grid_get_spacing (grid, &xspacing, &yspacing);
+      gimp_grid_get_offset  (grid, &xoffset,  &yoffset);
+
+      if (xspacing > 0.0)
+        {
+          gdouble nearest;
+
+          nearest = xoffset + RINT ((x - xoffset) / xspacing) * xspacing;
+
+          snapped |= gimp_image_snap_distance (x, nearest,
+                                               epsilon_x,
+                                               &mindist_x, tx);
+        }
+
+      if (yspacing > 0.0)
+        {
+          gdouble nearest;
+
+          nearest = yoffset + RINT ((y - yoffset) / yspacing) * yspacing;
+
+          snapped |= gimp_image_snap_distance (y, nearest,
+                                               epsilon_y,
+                                               &mindist_y, ty);
+        }
+    }
+
+  if (snap_to_canvas)
+    {
+      snapped |= gimp_image_snap_distance (x, 0,
+                                           epsilon_x,
+                                           &mindist_x, tx);
+      snapped |= gimp_image_snap_distance (x, gimp_image_get_width (image),
+                                           epsilon_x,
+                                           &mindist_x, tx);
+
+      snapped |= gimp_image_snap_distance (y, 0,
+                                           epsilon_y,
+                                           &mindist_y, ty);
+      snapped |= gimp_image_snap_distance (y, gimp_image_get_height (image),
+                                           epsilon_y,
+                                           &mindist_y, ty);
+    }
+
+  if (snap_to_vectors)
+    {
+      GimpVectors *vectors = gimp_image_get_active_vectors (image);
+      GimpStroke  *stroke  = NULL;
+      GimpCoords   coords  = { 0, 0, 0, 0, 0 };
+
+      coords.x = x;
+      coords.y = y;
+
+      while ((stroke = gimp_vectors_stroke_get_next (vectors, stroke)))
+        {
+          GimpCoords nearest;
+
+          if (gimp_stroke_nearest_point_get (stroke, &coords, 1.0,
+                                             &nearest,
+                                             NULL, NULL, NULL) >= 0)
+            {
+              snapped |= gimp_image_snap_distance (x, nearest.x,
+                                                   epsilon_x,
+                                                   &mindist_x, tx);
+              snapped |= gimp_image_snap_distance (y, nearest.y,
+                                                   epsilon_y,
+                                                   &mindist_y, ty);
+            }
+        }
+    }
+
+  return snapped;
+}
+
+gboolean
+gimp_image_snap_rectangle (GimpImage *image,
+                           gdouble    x1,
+                           gdouble    y1,
+                           gdouble    x2,
+                           gdouble    y2,
+                           gdouble   *tx1,
+                           gdouble   *ty1,
+                           gdouble    epsilon_x,
+                           gdouble    epsilon_y,
+                           gboolean   snap_to_guides,
+                           gboolean   snap_to_grid,
+                           gboolean   snap_to_canvas,
+                           gboolean   snap_to_vectors)
+{
+  gdouble  nx, ny;
+  gdouble  mindist_x = G_MAXDOUBLE;
+  gdouble  mindist_y = G_MAXDOUBLE;
+  gdouble  x_center  = (x1 + x2) / 2.0;
+  gdouble  y_center  = (y1 + y2) / 2.0;
+  gboolean snapped   = FALSE;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+  g_return_val_if_fail (tx1 != NULL, FALSE);
+  g_return_val_if_fail (ty1 != NULL, FALSE);
+
+  *tx1 = x1;
+  *ty1 = y1;
+
+  if (! gimp_image_get_guides (image))         snap_to_guides  = FALSE;
+  if (! gimp_image_get_grid (image))           snap_to_grid    = FALSE;
+  if (! gimp_image_get_active_vectors (image)) snap_to_vectors = FALSE;
+
+  if (! (snap_to_guides || snap_to_grid || snap_to_canvas || snap_to_vectors))
+    return FALSE;
+
+  /*  left edge  */
+  if (gimp_image_snap_x (image, x1, &nx,
+                         MIN (epsilon_x, mindist_x),
+                         snap_to_guides,
+                         snap_to_grid,
+                         snap_to_canvas))
+    {
+      mindist_x = ABS (nx - x1);
+      *tx1 = nx;
+      snapped = TRUE;
+    }
+
+  /*  right edge  */
+  if (gimp_image_snap_x (image, x2, &nx,
+                         MIN (epsilon_x, mindist_x),
+                         snap_to_guides,
+                         snap_to_grid,
+                         snap_to_canvas))
+    {
+      mindist_x = ABS (nx - x2);
+      *tx1 = RINT (x1 + (nx - x2));
+      snapped = TRUE;
+    }
+
+  /*  center, vertical  */
+  if (gimp_image_snap_x (image, x_center, &nx,
+                         MIN (epsilon_x, mindist_x),
+                         snap_to_guides,
+                         snap_to_grid,
+                         snap_to_canvas))
+    {
+      mindist_x = ABS (nx - x_center);
+      *tx1 = RINT (x1 + (nx - x_center));
+      snapped = TRUE;
+    }
+
+  /*  top edge  */
+  if (gimp_image_snap_y (image, y1, &ny,
+                         MIN (epsilon_y, mindist_y),
+                         snap_to_guides,
+                         snap_to_grid,
+                         snap_to_canvas))
+    {
+      mindist_y = ABS (ny - y1);
+      *ty1 = ny;
+      snapped = TRUE;
+    }
+
+  /*  bottom edge  */
+  if (gimp_image_snap_y (image, y2, &ny,
+                         MIN (epsilon_y, mindist_y),
+                         snap_to_guides,
+                         snap_to_grid,
+                         snap_to_canvas))
+    {
+      mindist_y = ABS (ny - y2);
+      *ty1 = RINT (y1 + (ny - y2));
+      snapped = TRUE;
+    }
+
+  /*  center, horizontal  */
+  if (gimp_image_snap_y (image, y_center, &ny,
+                         MIN (epsilon_y, mindist_y),
+                         snap_to_guides,
+                         snap_to_grid,
+                         snap_to_canvas))
+    {
+      mindist_y = ABS (ny - y_center);
+      *ty1 = RINT (y1 + (ny - y_center));
+      snapped = TRUE;
+    }
+
+  if (snap_to_vectors)
+    {
+      GimpVectors *vectors = gimp_image_get_active_vectors (image);
+      GimpStroke  *stroke  = NULL;
+      GimpCoords   coords1 = GIMP_COORDS_DEFAULT_VALUES;
+      GimpCoords   coords2 = GIMP_COORDS_DEFAULT_VALUES;
+
+      while ((stroke = gimp_vectors_stroke_get_next (vectors, stroke)))
+        {
+          GimpCoords nearest;
+          gdouble    dist;
+
+          /*  top edge  */
+
+          coords1.x = x1;
+          coords1.y = y1;
+          coords2.x = x2;
+          coords2.y = y1;
+
+          if (gimp_stroke_nearest_tangent_get (stroke, &coords1, &coords2,
+                                               1.0, &nearest,
+                                               NULL, NULL, NULL) >= 0)
+            {
+              snapped |= gimp_image_snap_distance (y1, nearest.y,
+                                                   epsilon_y,
+                                                   &mindist_y, ty1);
+            }
+
+          if (gimp_stroke_nearest_intersection_get (stroke, &coords1, &coords2,
+                                                    1.0, &nearest,
+                                                    NULL, NULL, NULL) >= 0)
+            {
+              snapped |= gimp_image_snap_distance (x1, nearest.x,
+                                                   epsilon_x,
+                                                   &mindist_x, tx1);
+            }
+
+          if (gimp_stroke_nearest_intersection_get (stroke, &coords2, &coords1,
+                                                    1.0, &nearest,
+                                                    NULL, NULL, NULL) >= 0)
+            {
+              dist = ABS (nearest.x - x2);
+
+              if (dist < MIN (epsilon_x, mindist_x))
+                {
+                  mindist_x = dist;
+                  *tx1 = RINT (x1 + (nearest.x - x2));
+                  snapped = TRUE;
+                }
+            }
+
+          /*  bottom edge  */
+
+          coords1.x = x1;
+          coords1.y = y2;
+          coords2.x = x2;
+          coords2.y = y2;
+
+          if (gimp_stroke_nearest_tangent_get (stroke, &coords1, &coords2,
+                                               1.0, &nearest,
+                                               NULL, NULL, NULL) >= 0)
+            {
+              dist = ABS (nearest.y - y2);
+
+              if (dist < MIN (epsilon_y, mindist_y))
+                {
+                  mindist_y = dist;
+                  *ty1 = RINT (y1 + (nearest.y - y2));
+                  snapped = TRUE;
+                }
+            }
+
+          if (gimp_stroke_nearest_intersection_get (stroke, &coords1, &coords2,
+                                                    1.0, &nearest,
+                                                    NULL, NULL, NULL) >= 0)
+            {
+              snapped |= gimp_image_snap_distance (x1, nearest.x,
+                                                   epsilon_x,
+                                                   &mindist_x, tx1);
+            }
+
+          if (gimp_stroke_nearest_intersection_get (stroke, &coords2, &coords1,
+                                                    1.0, &nearest,
+                                                    NULL, NULL, NULL) >= 0)
+            {
+              dist = ABS (nearest.x - x2);
+
+              if (dist < MIN (epsilon_x, mindist_x))
+                {
+                  mindist_x = dist;
+                  *tx1 = RINT (x1 + (nearest.x - x2));
+                  snapped = TRUE;
+                }
+            }
+
+          /*  left edge  */
+
+          coords1.x = x1;
+          coords1.y = y1;
+          coords2.x = x1;
+          coords2.y = y2;
+
+          if (gimp_stroke_nearest_tangent_get (stroke, &coords1, &coords2,
+                                               1.0, &nearest,
+                                               NULL, NULL, NULL) >= 0)
+            {
+              snapped |= gimp_image_snap_distance (x1, nearest.x,
+                                                   epsilon_x,
+                                                   &mindist_x, tx1);
+            }
+
+          if (gimp_stroke_nearest_intersection_get (stroke, &coords1, &coords2,
+                                                    1.0, &nearest,
+                                                    NULL, NULL, NULL) >= 0)
+            {
+              snapped |= gimp_image_snap_distance (y1, nearest.y,
+                                                   epsilon_y,
+                                                   &mindist_y, ty1);
+            }
+
+          if (gimp_stroke_nearest_intersection_get (stroke, &coords2, &coords1,
+                                                    1.0, &nearest,
+                                                    NULL, NULL, NULL) >= 0)
+            {
+              dist = ABS (nearest.y - y2);
+
+              if (dist < MIN (epsilon_y, mindist_y))
+                {
+                  mindist_y = dist;
+                  *ty1 = RINT (y1 + (nearest.y - y2));
+                  snapped = TRUE;
+                }
+            }
+
+          /*  right edge  */
+
+          coords1.x = x2;
+          coords1.y = y1;
+          coords2.x = x2;
+          coords2.y = y2;
+
+          if (gimp_stroke_nearest_tangent_get (stroke, &coords1, &coords2,
+                                               1.0, &nearest,
+                                               NULL, NULL, NULL) >= 0)
+            {
+              dist = ABS (nearest.x - x2);
+
+              if (dist < MIN (epsilon_x, mindist_x))
+                {
+                  mindist_x = dist;
+                  *tx1 = RINT (x1 + (nearest.x - x2));
+                  snapped = TRUE;
+                }
+            }
+
+          if (gimp_stroke_nearest_intersection_get (stroke, &coords1, &coords2,
+                                                    1.0, &nearest,
+                                                    NULL, NULL, NULL) >= 0)
+            {
+              snapped |= gimp_image_snap_distance (y1, nearest.y,
+                                                   epsilon_y,
+                                                   &mindist_y, ty1);
+            }
+
+          if (gimp_stroke_nearest_intersection_get (stroke, &coords2, &coords1,
+                                                    1.0, &nearest,
+                                                    NULL, NULL, NULL) >= 0)
+            {
+              dist = ABS (nearest.y - y2);
+
+              if (dist < MIN (epsilon_y, mindist_y))
+                {
+                  mindist_y = dist;
+                  *ty1 = RINT (y1 + (nearest.y - y2));
+                  snapped = TRUE;
+                }
+            }
+
+          /*  center  */
+
+          coords1.x = x_center;
+          coords1.y = y_center;
+
+          if (gimp_stroke_nearest_point_get (stroke, &coords1, 1.0,
+                                             &nearest,
+                                             NULL, NULL, NULL) >= 0)
+            {
+              if (gimp_image_snap_distance (x_center, nearest.x,
+                                            epsilon_x,
+                                            &mindist_x, &nx))
+                {
+                  mindist_x = ABS (nx - x_center);
+                  *tx1 = RINT (x1 + (nx - x_center));
+                  snapped = TRUE;
+                }
+
+              if (gimp_image_snap_distance (y_center, nearest.y,
+                                            epsilon_y,
+                                            &mindist_y, &ny))
+                {
+                  mindist_y = ABS (ny - y_center);
+                  *ty1 = RINT (y1 + (ny - y_center));
+                  snapped = TRUE;
+               }
+            }
+        }
+    }
+
+  return snapped;
+}
+
+/* private functions */
+
+/**
+ * gimp_image_snap_distance:
+ * @unsnapped: One coordinate of the unsnapped position
+ * @nearest:  One coordinate of a snapping position candidate
+ * @epsilon:  The snapping threshold
+ * @mindist:  The distance to the currently closest snapping target
+ * @target:   The currently closest snapping target
+ *
+ * Finds out if snapping occurs from position to a snapping candidate
+ * and sets the target accordingly.
+ *
+ * Return value: %TRUE if snapping occurred, %FALSE otherwise
+ */
+static gboolean
+gimp_image_snap_distance (const gdouble  unsnapped,
+                          const gdouble  nearest,
+                          const gdouble  epsilon,
+                          gdouble       *mindist,
+                          gdouble       *target)
+{
+  const gdouble dist = ABS (nearest - unsnapped);
+
+  if (dist < MIN (epsilon, *mindist))
+    {
+      *mindist = dist;
+      *target = nearest;
+
+      return TRUE;
+    }
+
+  return FALSE;
+}
diff --git a/app/core/gimpimage-snap.h b/app/core/gimpimage-snap.h
new file mode 100644
index 0000000..b0d5e4b
--- /dev/null
+++ b/app/core/gimpimage-snap.h
@@ -0,0 +1,63 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattisbvf
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_IMAGE_SNAP_H__
+#define __GIMP_IMAGE_SNAP_H__
+
+
+gboolean    gimp_image_snap_x         (GimpImage *image,
+                                       gdouble    x,
+                                       gdouble   *tx,
+                                       gdouble    epsilon_x,
+                                       gboolean   snap_to_guides,
+                                       gboolean   snap_to_grid,
+                                       gboolean   snap_to_canvas);
+gboolean    gimp_image_snap_y         (GimpImage *image,
+                                       gdouble    y,
+                                       gdouble   *ty,
+                                       gdouble    epsilon_y,
+                                       gboolean   snap_to_guides,
+                                       gboolean   snap_to_grid,
+                                       gboolean   snap_to_canvas);
+gboolean    gimp_image_snap_point     (GimpImage *image,
+                                       gdouble    x,
+                                       gdouble    y,
+                                       gdouble   *tx,
+                                       gdouble   *ty,
+                                       gdouble    epsilon_x,
+                                       gdouble    epsilon_y,
+                                       gboolean   snap_to_guides,
+                                       gboolean   snap_to_grid,
+                                       gboolean   snap_to_canvas,
+                                       gboolean   snap_to_vectors,
+                                       gboolean   show_all);
+gboolean    gimp_image_snap_rectangle (GimpImage *image,
+                                       gdouble    x1,
+                                       gdouble    y1,
+                                       gdouble    x2,
+                                       gdouble    y2,
+                                       gdouble   *tx1,
+                                       gdouble   *ty1,
+                                       gdouble    epsilon_x,
+                                       gdouble    epsilon_y,
+                                       gboolean   snap_to_guides,
+                                       gboolean   snap_to_grid,
+                                       gboolean   snap_to_canvas,
+                                       gboolean   snap_to_vectors);
+
+
+#endif /* __GIMP_IMAGE_SNAP_H__ */
diff --git a/app/core/gimpimage-symmetry.c b/app/core/gimpimage-symmetry.c
new file mode 100644
index 0000000..366f63e
--- /dev/null
+++ b/app/core/gimpimage-symmetry.c
@@ -0,0 +1,189 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpimage-symmetry.c
+ * Copyright (C) 2015 Jehan <jehan@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gegl.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "core-types.h"
+
+#include "gimpsymmetry.h"
+#include "gimpimage.h"
+#include "gimpimage-private.h"
+#include "gimpimage-symmetry.h"
+#include "gimpsymmetry-mandala.h"
+#include "gimpsymmetry-mirror.h"
+#include "gimpsymmetry-tiling.h"
+
+
+/**
+ * gimp_image_symmetry_list:
+ *
+ * Returns a list of #GType of all existing symmetries.
+ **/
+GList *
+gimp_image_symmetry_list (void)
+{
+  GList *list = NULL;
+
+  list = g_list_prepend (list, GINT_TO_POINTER (GIMP_TYPE_MIRROR));
+  list = g_list_prepend (list, GINT_TO_POINTER (GIMP_TYPE_TILING));
+  list = g_list_prepend (list, GINT_TO_POINTER (GIMP_TYPE_MANDALA));
+
+  return list;
+}
+
+/**
+ * gimp_image_symmetry_new:
+ * @image: the #GimpImage
+ * @type:  the #GType of the symmetry
+ *
+ * Creates a new #GimpSymmetry of @type attached to @image.
+ * @type must be a subtype of `GIMP_TYPE_SYMMETRY`.
+ * Note that using the base @type `GIMP_TYPE_SYMMETRY` creates an
+ * identity transformation.
+ *
+ * Returns: the new #GimpSymmetry.
+ **/
+GimpSymmetry *
+gimp_image_symmetry_new (GimpImage *image,
+                         GType      type)
+{
+  GimpSymmetry *sym = NULL;
+
+  g_return_val_if_fail (g_type_is_a (type, GIMP_TYPE_SYMMETRY), NULL);
+
+  sym = g_object_new (type,
+                      "image", image,
+                      NULL);
+
+  return sym;
+}
+
+/**
+ * gimp_image_symmetry_add:
+ * @image: the #GimpImage
+ * @type:  the #GType of the symmetry
+ *
+ * Add a symmetry of type @type to @image and make it the
+ * active transformation.
+ **/
+void
+gimp_image_symmetry_add (GimpImage    *image,
+                         GimpSymmetry *sym)
+{
+  GimpImagePrivate *private;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (GIMP_IS_SYMMETRY (sym));
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  private->symmetries = g_list_prepend (private->symmetries,
+                                        g_object_ref (sym));
+}
+
+/**
+ * gimp_image_symmetry_remove:
+ * @image:   the #GimpImage
+ * @sym: the #GimpSymmetry
+ *
+ * Remove @sym from the list of symmetries of @image.
+ * If it was the active transformation, unselect it first.
+ **/
+void
+gimp_image_symmetry_remove (GimpImage    *image,
+                            GimpSymmetry *sym)
+{
+  GimpImagePrivate *private;
+
+  g_return_if_fail (GIMP_IS_SYMMETRY (sym));
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  if (private->active_symmetry == sym)
+    gimp_image_set_active_symmetry (image, GIMP_TYPE_SYMMETRY);
+
+  private->symmetries = g_list_remove (private->symmetries, sym);
+  g_object_unref (sym);
+}
+
+/**
+ * gimp_image_symmetry_get:
+ * @image: the #GimpImage
+ *
+ * Returns: the list of #GimpSymmetry set on @image.
+ * The returned list belongs to @image and should not be freed.
+ **/
+GList *
+gimp_image_symmetry_get (GimpImage *image)
+{
+  GimpImagePrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  return private->symmetries;
+}
+
+/**
+ * gimp_image_set_active_symmetry:
+ * @image: the #GimpImage
+ * @type:  the #GType of the symmetry
+ *
+ * Select the symmetry of type @type.
+ * Using the GType allows to select a transformation without
+ * knowing whether one of the same @type was already created.
+ *
+ * Returns TRUE on success, FALSE if no such symmetry was found.
+ **/
+gboolean
+gimp_image_set_active_symmetry (GimpImage *image,
+                                GType      type)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+
+  g_object_set (image,
+                "symmetry", type,
+                NULL);
+
+  return TRUE;
+}
+
+/**
+ * gimp_image_get_active_symmetry:
+ * @image: the #GimpImage
+ *
+ * Returns the #GimpSymmetry transformation active on @image.
+ **/
+GimpSymmetry *
+gimp_image_get_active_symmetry (GimpImage *image)
+{
+  GimpImagePrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  return private->active_symmetry;
+}
diff --git a/app/core/gimpimage-symmetry.h b/app/core/gimpimage-symmetry.h
new file mode 100644
index 0000000..9211382
--- /dev/null
+++ b/app/core/gimpimage-symmetry.h
@@ -0,0 +1,40 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpimage-symmetry.h
+ * Copyright (C) 2015 Jehan <jehan@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_IMAGE_SYMMETRY_H__
+#define __GIMP_IMAGE_SYMMETRY_H__
+
+
+GList        * gimp_image_symmetry_list       (void);
+
+GimpSymmetry * gimp_image_symmetry_new        (GimpImage    *image,
+                                               GType         type);
+void           gimp_image_symmetry_add        (GimpImage    *image,
+                                               GimpSymmetry *sym);
+void           gimp_image_symmetry_remove     (GimpImage    *image,
+                                               GimpSymmetry *sym);
+GList        * gimp_image_symmetry_get        (GimpImage    *image);
+
+gboolean       gimp_image_set_active_symmetry (GimpImage    *image,
+                                               GType         type);
+GimpSymmetry * gimp_image_get_active_symmetry (GimpImage    *image);
+
+
+#endif  /*  __GIMP_IMAGE_SYMMETRY_H__  */
diff --git a/app/core/gimpimage-transform.c b/app/core/gimpimage-transform.c
new file mode 100644
index 0000000..afe4cfc
--- /dev/null
+++ b/app/core/gimpimage-transform.c
@@ -0,0 +1,338 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpimage-transform.c
+ * Copyright (C) 2019 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpmath/gimpmath.h"
+
+#include "core-types.h"
+
+#include "vectors/gimpvectors.h"
+
+#include "gimp.h"
+#include "gimp-transform-resize.h"
+#include "gimp-transform-utils.h"
+#include "gimpchannel.h"
+#include "gimpcontext.h"
+#include "gimpguide.h"
+#include "gimpimage.h"
+#include "gimpimage-guides.h"
+#include "gimpimage-sample-points.h"
+#include "gimpimage-transform.h"
+#include "gimpimage-undo.h"
+#include "gimpimage-undo-push.h"
+#include "gimpitem.h"
+#include "gimpobjectqueue.h"
+#include "gimpprogress.h"
+#include "gimpsamplepoint.h"
+
+
+#define EPSILON 1e-6
+
+
+/*  local function prototypes  */
+
+static void    gimp_image_transform_guides        (GimpImage           *image,
+                                                   const GimpMatrix3   *matrix,
+                                                   const GeglRectangle *old_bounds);
+static void    gimp_image_transform_sample_points (GimpImage           *image,
+                                                   const GimpMatrix3   *matrix,
+                                                   const GeglRectangle *old_bounds);
+
+
+/*  private functions  */
+
+static void
+gimp_image_transform_guides (GimpImage           *image,
+                             const GimpMatrix3   *matrix,
+                             const GeglRectangle *old_bounds)
+{
+  GList *iter;
+
+  for (iter = gimp_image_get_guides (image); iter;)
+    {
+      GimpGuide           *guide           = iter->data;
+      GimpOrientationType  old_orientation = gimp_guide_get_orientation (guide);
+      gint                 old_position    = gimp_guide_get_position (guide);
+      GimpOrientationType  new_orientation;
+      gint                 new_position;
+      GimpVector2          vertices[2];
+      gint                 n_vertices;
+      GimpVector2          diff;
+
+      iter = g_list_next (iter);
+
+      switch (old_orientation)
+        {
+        case GIMP_ORIENTATION_HORIZONTAL:
+          vertices[0].x = old_bounds->x;
+          vertices[0].y = old_bounds->y + old_position;
+
+          vertices[1].x = old_bounds->x + old_bounds->width / 2.0;
+          vertices[1].y = old_bounds->y + old_position;
+          break;
+
+        case GIMP_ORIENTATION_VERTICAL:
+          vertices[0].x = old_bounds->x + old_position;
+          vertices[0].y = old_bounds->y;
+
+          vertices[1].x = old_bounds->x + old_position;
+          vertices[1].y = old_bounds->y + old_bounds->height / 2.0;
+          break;
+
+        case GIMP_ORIENTATION_UNKNOWN:
+          g_return_if_reached ();
+        }
+
+      gimp_transform_polygon (matrix,
+                              vertices, 2, FALSE,
+                              vertices, &n_vertices);
+
+      if (n_vertices < 2)
+        {
+          gimp_image_remove_guide (image, guide, TRUE);
+
+          continue;
+        }
+
+      gimp_vector2_sub (&diff, &vertices[1], &vertices[0]);
+
+      if (gimp_vector2_length (&diff) <= EPSILON)
+        {
+          gimp_image_remove_guide (image, guide, TRUE);
+
+          continue;
+        }
+
+      if (fabs (diff.x) >= fabs (diff.y))
+        {
+          new_orientation = GIMP_ORIENTATION_HORIZONTAL;
+          new_position    = SIGNED_ROUND (vertices[1].y);
+
+          if (new_position < 0 || new_position > gimp_image_get_height (image))
+            {
+              gimp_image_remove_guide (image, guide, TRUE);
+
+              continue;
+            }
+        }
+      else
+        {
+          new_orientation = GIMP_ORIENTATION_VERTICAL;
+          new_position    = SIGNED_ROUND (vertices[1].x);
+
+          if (new_position < 0 || new_position > gimp_image_get_width (image))
+            {
+              gimp_image_remove_guide (image, guide, TRUE);
+
+              continue;
+            }
+        }
+
+      if (new_orientation != old_orientation ||
+          new_position    != old_position)
+        {
+          gimp_image_undo_push_guide (image, NULL, guide);
+
+          gimp_guide_set_orientation (guide, new_orientation);
+          gimp_guide_set_position    (guide, new_position);
+
+          gimp_image_guide_moved (image, guide);
+        }
+    }
+}
+
+static void
+gimp_image_transform_sample_points (GimpImage           *image,
+                                    const GimpMatrix3   *matrix,
+                                    const GeglRectangle *old_bounds)
+{
+  GList *iter;
+
+  for (iter = gimp_image_get_sample_points (image); iter;)
+    {
+      GimpSamplePoint     *sample_point = iter->data;
+      gint                 old_x;
+      gint                 old_y;
+      gint                 new_x;
+      gint                 new_y;
+      GimpVector2          vertices[1];
+      gint                 n_vertices;
+
+      iter = g_list_next (iter);
+
+      gimp_sample_point_get_position (sample_point, &old_x, &old_y);
+
+      vertices[0].x = old_x;
+      vertices[0].y = old_y;
+
+      gimp_transform_polygon (matrix,
+                              vertices, 1, FALSE,
+                              vertices, &n_vertices);
+
+      if (n_vertices < 1)
+        {
+          gimp_image_remove_sample_point (image, sample_point, TRUE);
+
+          continue;
+        }
+
+      new_x = SIGNED_ROUND (vertices[0].x);
+      new_y = SIGNED_ROUND (vertices[0].y);
+
+      if (new_x < 0 || new_x >= gimp_image_get_width  (image) ||
+          new_y < 0 || new_y >= gimp_image_get_height (image))
+        {
+          gimp_image_remove_sample_point (image, sample_point, TRUE);
+
+          continue;
+        }
+
+      if (new_x != old_x || new_y != old_y)
+        gimp_image_move_sample_point (image, sample_point, new_x, new_y, TRUE);
+    }
+}
+
+
+/*  public functions  */
+
+void
+gimp_image_transform (GimpImage              *image,
+                      GimpContext            *context,
+                      const GimpMatrix3      *matrix,
+                      GimpTransformDirection  direction,
+                      GimpInterpolationType   interpolation_type,
+                      GimpTransformResize     clip_result,
+                      GimpProgress           *progress)
+{
+  GimpObjectQueue *queue;
+  GimpItem        *item;
+  GimpMatrix3      transform;
+  GeglRectangle    old_bounds;
+  GeglRectangle    new_bounds;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+  g_return_if_fail (matrix != NULL);
+  g_return_if_fail (progress == NULL || GIMP_IS_PROGRESS (progress));
+
+  gimp_set_busy (image->gimp);
+
+  old_bounds.x      = 0;
+  old_bounds.y      = 0;
+  old_bounds.width  = gimp_image_get_width  (image);
+  old_bounds.height = gimp_image_get_height (image);
+
+  transform = *matrix;
+
+  if (direction == GIMP_TRANSFORM_BACKWARD)
+    gimp_matrix3_invert (&transform);
+
+  gimp_transform_resize_boundary (&transform, clip_result,
+
+                                  old_bounds.x,
+                                  old_bounds.y,
+                                  old_bounds.x + old_bounds.width,
+                                  old_bounds.y + old_bounds.height,
+
+                                  &new_bounds.x,
+                                  &new_bounds.y,
+                                  &new_bounds.width,
+                                  &new_bounds.height);
+
+  new_bounds.width  -= new_bounds.x;
+  new_bounds.height -= new_bounds.y;
+
+  gimp_matrix3_translate (&transform,
+                          old_bounds.x - new_bounds.x,
+                          old_bounds.y - new_bounds.y);
+
+  queue    = gimp_object_queue_new (progress);
+  progress = GIMP_PROGRESS (queue);
+
+  gimp_object_queue_push_container (queue, gimp_image_get_layers (image));
+  gimp_object_queue_push (queue, gimp_image_get_mask (image));
+  gimp_object_queue_push_container (queue, gimp_image_get_channels (image));
+  gimp_object_queue_push_container (queue, gimp_image_get_vectors (image));
+
+  g_object_freeze_notify (G_OBJECT (image));
+
+  gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_IMAGE_TRANSFORM, NULL);
+
+  /*  Transform all layers, channels (including selection mask), and vectors  */
+  while ((item = gimp_object_queue_pop (queue)))
+    {
+      GimpTransformResize clip = GIMP_TRANSFORM_RESIZE_ADJUST;
+
+      if (GIMP_IS_CHANNEL (item))
+        clip = clip_result;
+
+      gimp_item_transform (item,
+                           context,
+                           &transform, direction,
+                           interpolation_type, clip,
+                           progress);
+
+      if (GIMP_IS_VECTORS (item))
+        gimp_item_set_size (item, new_bounds.width, new_bounds.height);
+    }
+
+  /*  Resize the image (if needed)  */
+  if (! gegl_rectangle_equal (&new_bounds, &old_bounds))
+    {
+      gimp_image_undo_push_image_size (image,
+                                       NULL,
+                                       new_bounds.x,
+                                       new_bounds.y,
+                                       new_bounds.width,
+                                       new_bounds.height);
+
+      g_object_set (image,
+                    "width",  new_bounds.width,
+                    "height", new_bounds.height,
+                    NULL);
+    }
+
+  /*  Transform all Guides  */
+  gimp_image_transform_guides (image, &transform, &old_bounds);
+
+  /*  Transform all sample points  */
+  gimp_image_transform_sample_points (image, &transform, &old_bounds);
+
+  gimp_image_undo_group_end (image);
+
+  g_object_unref (queue);
+
+  if (! gegl_rectangle_equal (&new_bounds, &old_bounds))
+    {
+      gimp_image_size_changed_detailed (image,
+                                        old_bounds.x - new_bounds.x,
+                                        old_bounds.y - new_bounds.y,
+                                        old_bounds.width,
+                                        old_bounds.height);
+    }
+
+  g_object_thaw_notify (G_OBJECT (image));
+
+  gimp_unset_busy (image->gimp);
+}
diff --git a/app/core/gimpimage-transform.h b/app/core/gimpimage-transform.h
new file mode 100644
index 0000000..63a851d
--- /dev/null
+++ b/app/core/gimpimage-transform.h
@@ -0,0 +1,34 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattisbvf
+ *
+ * gimpimage-transform.h
+ * Copyright (C) 2019 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_IMAGE_TRANSFORM_H__
+#define __GIMP_IMAGE_TRANSFORM_H__
+
+
+void   gimp_image_transform (GimpImage              *image,
+                             GimpContext            *context,
+                             const GimpMatrix3      *matrix,
+                             GimpTransformDirection  direction,
+                             GimpInterpolationType   interpolation_type,
+                             GimpTransformResize     clip_result,
+                             GimpProgress           *progress);
+
+
+#endif /* __GIMP_IMAGE_TRANSFORM_H__ */
diff --git a/app/core/gimpimage-undo-push.c b/app/core/gimpimage-undo-push.c
new file mode 100644
index 0000000..b96c4b4
--- /dev/null
+++ b/app/core/gimpimage-undo-push.c
@@ -0,0 +1,1060 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+
+#include "core-types.h"
+
+#include "gimp.h"
+#include "gimpchannelpropundo.h"
+#include "gimpchannelundo.h"
+#include "gimpdrawablemodundo.h"
+#include "gimpdrawableundo.h"
+#include "gimpfloatingselectionundo.h"
+#include "gimpgrid.h"
+#include "gimpgrouplayer.h"
+#include "gimpgrouplayerundo.h"
+#include "gimpguide.h"
+#include "gimpguideundo.h"
+#include "gimpimage.h"
+#include "gimpimage-undo.h"
+#include "gimpimage-undo-push.h"
+#include "gimpimageundo.h"
+#include "gimpitempropundo.h"
+#include "gimplayermask.h"
+#include "gimplayermaskpropundo.h"
+#include "gimplayermaskundo.h"
+#include "gimplayerpropundo.h"
+#include "gimplayerundo.h"
+#include "gimpmaskundo.h"
+#include "gimpsamplepoint.h"
+#include "gimpsamplepointundo.h"
+#include "gimpselection.h"
+
+#include "text/gimptextlayer.h"
+#include "text/gimptextundo.h"
+
+#include "vectors/gimpvectors.h"
+#include "vectors/gimpvectorsmodundo.h"
+#include "vectors/gimpvectorspropundo.h"
+#include "vectors/gimpvectorsundo.h"
+
+#include "gimp-intl.h"
+
+
+/**************************/
+/*  Image Property Undos  */
+/**************************/
+
+GimpUndo *
+gimp_image_undo_push_image_type (GimpImage   *image,
+                                 const gchar *undo_desc)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_IMAGE_UNDO,
+                               GIMP_UNDO_IMAGE_TYPE, undo_desc,
+                               GIMP_DIRTY_IMAGE,
+                               NULL);
+}
+
+GimpUndo *
+gimp_image_undo_push_image_precision (GimpImage   *image,
+                                      const gchar *undo_desc)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_IMAGE_UNDO,
+                               GIMP_UNDO_IMAGE_PRECISION, undo_desc,
+                               GIMP_DIRTY_IMAGE,
+                               NULL);
+}
+
+GimpUndo *
+gimp_image_undo_push_image_size (GimpImage   *image,
+                                 const gchar *undo_desc,
+                                 gint         previous_origin_x,
+                                 gint         previous_origin_y,
+                                 gint         previous_width,
+                                 gint         previous_height)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_IMAGE_UNDO,
+                               GIMP_UNDO_IMAGE_SIZE, undo_desc,
+                               GIMP_DIRTY_IMAGE | GIMP_DIRTY_IMAGE_SIZE,
+                               "previous-origin-x", previous_origin_x,
+                               "previous-origin-y", previous_origin_y,
+                               "previous-width",    previous_width,
+                               "previous-height",   previous_height,
+                               NULL);
+}
+
+GimpUndo *
+gimp_image_undo_push_image_resolution (GimpImage   *image,
+                                       const gchar *undo_desc)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_IMAGE_UNDO,
+                               GIMP_UNDO_IMAGE_RESOLUTION, undo_desc,
+                               GIMP_DIRTY_IMAGE,
+                               NULL);
+}
+
+GimpUndo *
+gimp_image_undo_push_image_grid (GimpImage   *image,
+                                 const gchar *undo_desc,
+                                 GimpGrid    *grid)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_GRID (grid), NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_IMAGE_UNDO,
+                               GIMP_UNDO_IMAGE_GRID, undo_desc,
+                               GIMP_DIRTY_IMAGE_META,
+                               "grid", grid,
+                               NULL);
+}
+
+GimpUndo *
+gimp_image_undo_push_image_colormap (GimpImage   *image,
+                                     const gchar *undo_desc)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_IMAGE_UNDO,
+                               GIMP_UNDO_IMAGE_COLORMAP, undo_desc,
+                               GIMP_DIRTY_IMAGE,
+                               NULL);
+}
+
+GimpUndo *
+gimp_image_undo_push_image_color_managed (GimpImage   *image,
+                                          const gchar *undo_desc)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_IMAGE_UNDO,
+                               GIMP_UNDO_IMAGE_COLOR_MANAGED, undo_desc,
+                               GIMP_DIRTY_IMAGE,
+                               NULL);
+}
+
+GimpUndo *
+gimp_image_undo_push_image_metadata (GimpImage   *image,
+                                     const gchar *undo_desc)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_IMAGE_UNDO,
+                               GIMP_UNDO_IMAGE_METADATA, undo_desc,
+                               GIMP_DIRTY_IMAGE_META,
+                               NULL);
+}
+
+GimpUndo *
+gimp_image_undo_push_image_parasite (GimpImage          *image,
+                                     const gchar        *undo_desc,
+                                     const GimpParasite *parasite)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (parasite != NULL, NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_IMAGE_UNDO,
+                               GIMP_UNDO_PARASITE_ATTACH, undo_desc,
+                               GIMP_DIRTY_IMAGE_META,
+                               "parasite-name", gimp_parasite_name (parasite),
+                               NULL);
+}
+
+GimpUndo *
+gimp_image_undo_push_image_parasite_remove (GimpImage   *image,
+                                            const gchar *undo_desc,
+                                            const gchar *name)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (name != NULL, NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_IMAGE_UNDO,
+                               GIMP_UNDO_PARASITE_REMOVE, undo_desc,
+                               GIMP_DIRTY_IMAGE_META,
+                               "parasite-name", name,
+                               NULL);
+}
+
+
+/********************************/
+/*  Guide & Sample Point Undos  */
+/********************************/
+
+GimpUndo *
+gimp_image_undo_push_guide (GimpImage   *image,
+                            const gchar *undo_desc,
+                            GimpGuide   *guide)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_GUIDE (guide), NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_GUIDE_UNDO,
+                               GIMP_UNDO_GUIDE, undo_desc,
+                               GIMP_DIRTY_IMAGE_META,
+                               "aux-item", guide,
+                               NULL);
+}
+
+GimpUndo *
+gimp_image_undo_push_sample_point (GimpImage       *image,
+                                   const gchar     *undo_desc,
+                                   GimpSamplePoint *sample_point)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_SAMPLE_POINT (sample_point), NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_SAMPLE_POINT_UNDO,
+                               GIMP_UNDO_SAMPLE_POINT, undo_desc,
+                               GIMP_DIRTY_IMAGE_META,
+                               "aux-item", sample_point,
+                               NULL);
+}
+
+
+/********************/
+/*  Drawable Undos  */
+/********************/
+
+GimpUndo *
+gimp_image_undo_push_drawable (GimpImage    *image,
+                               const gchar  *undo_desc,
+                               GimpDrawable *drawable,
+                               GeglBuffer   *buffer,
+                               gint          x,
+                               gint          y)
+{
+  GimpItem *item;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
+  g_return_val_if_fail (GEGL_IS_BUFFER (buffer), NULL);
+
+  item = GIMP_ITEM (drawable);
+
+  g_return_val_if_fail (gimp_item_is_attached (item), NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_DRAWABLE_UNDO,
+                               GIMP_UNDO_DRAWABLE, undo_desc,
+                               GIMP_DIRTY_ITEM | GIMP_DIRTY_DRAWABLE,
+                               "item",   item,
+                               "buffer", buffer,
+                               "x",      x,
+                               "y",      y,
+                               NULL);
+}
+
+GimpUndo *
+gimp_image_undo_push_drawable_mod (GimpImage    *image,
+                                   const gchar  *undo_desc,
+                                   GimpDrawable *drawable,
+                                   gboolean      copy_buffer)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (drawable)), NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_DRAWABLE_MOD_UNDO,
+                               GIMP_UNDO_DRAWABLE_MOD, undo_desc,
+                               GIMP_DIRTY_ITEM | GIMP_DIRTY_DRAWABLE,
+                               "item",        drawable,
+                               "copy-buffer", copy_buffer,
+                               NULL);
+}
+
+
+/****************/
+/*  Mask Undos  */
+/****************/
+
+GimpUndo *
+gimp_image_undo_push_mask (GimpImage   *image,
+                           const gchar *undo_desc,
+                           GimpChannel *mask)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_CHANNEL (mask), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (mask)), NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_MASK_UNDO,
+                               GIMP_UNDO_MASK, undo_desc,
+                               GIMP_IS_SELECTION (mask) ?
+                               GIMP_DIRTY_SELECTION :
+                               GIMP_DIRTY_ITEM | GIMP_DIRTY_DRAWABLE,
+                               "item", mask,
+                               NULL);
+}
+
+GimpUndo *
+gimp_image_undo_push_mask_precision (GimpImage   *image,
+                                     const gchar *undo_desc,
+                                     GimpChannel *mask)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_CHANNEL (mask), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (mask)), NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_MASK_UNDO,
+                               GIMP_UNDO_MASK, undo_desc,
+                               GIMP_IS_SELECTION (mask) ?
+                               GIMP_DIRTY_SELECTION :
+                               GIMP_DIRTY_ITEM | GIMP_DIRTY_DRAWABLE,
+                               "item",           mask,
+                               "convert-format", TRUE,
+                               NULL);
+}
+
+
+/****************/
+/*  Item Undos  */
+/****************/
+
+GimpUndo *
+gimp_image_undo_push_item_reorder (GimpImage   *image,
+                                   const gchar *undo_desc,
+                                   GimpItem    *item)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_ITEM (item), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (item), NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_ITEM_PROP_UNDO,
+                               GIMP_UNDO_ITEM_REORDER, undo_desc,
+                               GIMP_DIRTY_IMAGE_STRUCTURE,
+                               "item", item,
+                               NULL);
+}
+
+GimpUndo *
+gimp_image_undo_push_item_rename (GimpImage   *image,
+                                  const gchar *undo_desc,
+                                  GimpItem    *item)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_ITEM (item), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (item), NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_ITEM_PROP_UNDO,
+                               GIMP_UNDO_ITEM_RENAME, undo_desc,
+                               GIMP_DIRTY_ITEM_META,
+                               "item", item,
+                               NULL);
+}
+
+GimpUndo *
+gimp_image_undo_push_item_displace (GimpImage   *image,
+                                    const gchar *undo_desc,
+                                    GimpItem    *item)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_ITEM (item), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (item), NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_ITEM_PROP_UNDO,
+                               GIMP_UNDO_ITEM_DISPLACE, undo_desc,
+                               GIMP_IS_DRAWABLE (item) ?
+                               GIMP_DIRTY_ITEM | GIMP_DIRTY_DRAWABLE :
+                               GIMP_DIRTY_ITEM | GIMP_DIRTY_VECTORS,
+                               "item", item,
+                               NULL);
+}
+
+GimpUndo *
+gimp_image_undo_push_item_visibility (GimpImage   *image,
+                                      const gchar *undo_desc,
+                                      GimpItem    *item)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_ITEM (item), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (item), NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_ITEM_PROP_UNDO,
+                               GIMP_UNDO_ITEM_VISIBILITY, undo_desc,
+                               GIMP_DIRTY_ITEM_META,
+                               "item", item,
+                               NULL);
+}
+
+GimpUndo *
+gimp_image_undo_push_item_linked (GimpImage   *image,
+                                  const gchar *undo_desc,
+                                  GimpItem    *item)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_ITEM (item), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (item), NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_ITEM_PROP_UNDO,
+                               GIMP_UNDO_ITEM_LINKED, undo_desc,
+                               GIMP_DIRTY_ITEM_META,
+                               "item", item,
+                               NULL);
+}
+
+GimpUndo *
+gimp_image_undo_push_item_color_tag (GimpImage   *image,
+                                     const gchar *undo_desc,
+                                     GimpItem    *item)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_ITEM (item), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (item), NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_ITEM_PROP_UNDO,
+                               GIMP_UNDO_ITEM_COLOR_TAG, undo_desc,
+                               GIMP_DIRTY_ITEM_META,
+                               "item", item,
+                               NULL);
+}
+
+GimpUndo *
+gimp_image_undo_push_item_lock_content (GimpImage   *image,
+                                        const gchar *undo_desc,
+                                        GimpItem    *item)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_ITEM (item), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (item), NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_ITEM_PROP_UNDO,
+                               GIMP_UNDO_ITEM_LOCK_CONTENT, undo_desc,
+                               GIMP_DIRTY_ITEM_META,
+                               "item", item,
+                               NULL);
+}
+
+GimpUndo *
+gimp_image_undo_push_item_lock_position (GimpImage   *image,
+                                         const gchar *undo_desc,
+                                         GimpItem    *item)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_ITEM (item), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (item), NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_ITEM_PROP_UNDO,
+                               GIMP_UNDO_ITEM_LOCK_POSITION, undo_desc,
+                               GIMP_DIRTY_ITEM_META,
+                               "item", item,
+                               NULL);
+}
+
+GimpUndo *
+gimp_image_undo_push_item_parasite (GimpImage          *image,
+                                    const gchar        *undo_desc,
+                                    GimpItem           *item,
+                                    const GimpParasite *parasite)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_ITEM (item), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (item), NULL);
+  g_return_val_if_fail (parasite != NULL, NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_ITEM_PROP_UNDO,
+                               GIMP_UNDO_PARASITE_ATTACH, undo_desc,
+                               GIMP_DIRTY_ITEM_META,
+                               "item",          item,
+                               "parasite-name", gimp_parasite_name (parasite),
+                               NULL);
+}
+
+GimpUndo *
+gimp_image_undo_push_item_parasite_remove (GimpImage   *image,
+                                           const gchar *undo_desc,
+                                           GimpItem    *item,
+                                           const gchar *name)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_ITEM (item), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (item), NULL);
+  g_return_val_if_fail (name != NULL, NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_ITEM_PROP_UNDO,
+                               GIMP_UNDO_PARASITE_REMOVE, undo_desc,
+                               GIMP_DIRTY_ITEM_META,
+                               "item",          item,
+                               "parasite-name", name,
+                               NULL);
+}
+
+
+/*****************/
+/*  Layer Undos  */
+/*****************/
+
+GimpUndo *
+gimp_image_undo_push_layer_add (GimpImage   *image,
+                                const gchar *undo_desc,
+                                GimpLayer   *layer,
+                                GimpLayer   *prev_layer)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_LAYER (layer), NULL);
+  g_return_val_if_fail (! gimp_item_is_attached (GIMP_ITEM (layer)), NULL);
+  g_return_val_if_fail (prev_layer == NULL || GIMP_IS_LAYER (prev_layer),
+                        NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_LAYER_UNDO,
+                               GIMP_UNDO_LAYER_ADD, undo_desc,
+                               GIMP_DIRTY_IMAGE_STRUCTURE,
+                               "item",       layer,
+                               "prev-layer", prev_layer,
+                               NULL);
+}
+
+GimpUndo *
+gimp_image_undo_push_layer_remove (GimpImage   *image,
+                                   const gchar *undo_desc,
+                                   GimpLayer   *layer,
+                                   GimpLayer   *prev_parent,
+                                   gint         prev_position,
+                                   GimpLayer   *prev_layer)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_LAYER (layer), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (layer)), NULL);
+  g_return_val_if_fail (prev_parent == NULL || GIMP_IS_LAYER (prev_parent),
+                        NULL);
+  g_return_val_if_fail (prev_layer == NULL || GIMP_IS_LAYER (prev_layer),
+                        NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_LAYER_UNDO,
+                               GIMP_UNDO_LAYER_REMOVE, undo_desc,
+                               GIMP_DIRTY_IMAGE_STRUCTURE,
+                               "item",          layer,
+                               "prev-parent",   prev_parent,
+                               "prev-position", prev_position,
+                               "prev-layer",    prev_layer,
+                               NULL);
+}
+
+GimpUndo *
+gimp_image_undo_push_layer_mode (GimpImage   *image,
+                                 const gchar *undo_desc,
+                                 GimpLayer   *layer)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_LAYER (layer), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (layer)), NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_LAYER_PROP_UNDO,
+                               GIMP_UNDO_LAYER_MODE, undo_desc,
+                               GIMP_DIRTY_ITEM_META,
+                               "item", layer,
+                               NULL);
+}
+
+GimpUndo *
+gimp_image_undo_push_layer_opacity (GimpImage   *image,
+                                    const gchar *undo_desc,
+                                    GimpLayer   *layer)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_LAYER (layer), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (layer)), NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_LAYER_PROP_UNDO,
+                               GIMP_UNDO_LAYER_OPACITY, undo_desc,
+                               GIMP_DIRTY_ITEM_META,
+                               "item", layer,
+                               NULL);
+}
+
+GimpUndo *
+gimp_image_undo_push_layer_lock_alpha (GimpImage   *image,
+                                       const gchar *undo_desc,
+                                       GimpLayer   *layer)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_LAYER (layer), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (layer)), NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_LAYER_PROP_UNDO,
+                               GIMP_UNDO_LAYER_LOCK_ALPHA, undo_desc,
+                               GIMP_DIRTY_ITEM_META,
+                               "item", layer,
+                               NULL);
+}
+
+
+/***********************/
+/*  Group Layer Undos  */
+/***********************/
+
+GimpUndo *
+gimp_image_undo_push_group_layer_suspend_resize (GimpImage      *image,
+                                                 const gchar    *undo_desc,
+                                                 GimpGroupLayer *group)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_GROUP_LAYER (group), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (group)), NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_GROUP_LAYER_UNDO,
+                               GIMP_UNDO_GROUP_LAYER_SUSPEND_RESIZE, undo_desc,
+                               GIMP_DIRTY_ITEM | GIMP_DIRTY_DRAWABLE,
+                               "item",  group,
+                               NULL);
+}
+
+GimpUndo *
+gimp_image_undo_push_group_layer_resume_resize (GimpImage      *image,
+                                                const gchar    *undo_desc,
+                                                GimpGroupLayer *group)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_GROUP_LAYER (group), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (group)), NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_GROUP_LAYER_UNDO,
+                               GIMP_UNDO_GROUP_LAYER_RESUME_RESIZE, undo_desc,
+                               GIMP_DIRTY_ITEM | GIMP_DIRTY_DRAWABLE,
+                               "item",  group,
+                               NULL);
+}
+
+GimpUndo *
+gimp_image_undo_push_group_layer_suspend_mask (GimpImage      *image,
+                                               const gchar    *undo_desc,
+                                               GimpGroupLayer *group)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_GROUP_LAYER (group), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (group)), NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_GROUP_LAYER_UNDO,
+                               GIMP_UNDO_GROUP_LAYER_SUSPEND_MASK, undo_desc,
+                               GIMP_DIRTY_ITEM | GIMP_DIRTY_DRAWABLE,
+                               "item",  group,
+                               NULL);
+}
+
+GimpUndo *
+gimp_image_undo_push_group_layer_resume_mask (GimpImage      *image,
+                                              const gchar    *undo_desc,
+                                              GimpGroupLayer *group)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_GROUP_LAYER (group), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (group)), NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_GROUP_LAYER_UNDO,
+                               GIMP_UNDO_GROUP_LAYER_RESUME_MASK, undo_desc,
+                               GIMP_DIRTY_ITEM | GIMP_DIRTY_DRAWABLE,
+                               "item",  group,
+                               NULL);
+}
+
+GimpUndo *
+gimp_image_undo_push_group_layer_start_transform (GimpImage      *image,
+                                                  const gchar    *undo_desc,
+                                                  GimpGroupLayer *group)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_GROUP_LAYER (group), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (group)), NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_GROUP_LAYER_UNDO,
+                               GIMP_UNDO_GROUP_LAYER_START_TRANSFORM, undo_desc,
+                               GIMP_DIRTY_ITEM | GIMP_DIRTY_DRAWABLE,
+                               "item",  group,
+                               NULL);
+}
+
+GimpUndo *
+gimp_image_undo_push_group_layer_end_transform (GimpImage      *image,
+                                                const gchar    *undo_desc,
+                                                GimpGroupLayer *group)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_GROUP_LAYER (group), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (group)), NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_GROUP_LAYER_UNDO,
+                               GIMP_UNDO_GROUP_LAYER_END_TRANSFORM, undo_desc,
+                               GIMP_DIRTY_ITEM | GIMP_DIRTY_DRAWABLE,
+                               "item",  group,
+                               NULL);
+}
+
+GimpUndo *
+gimp_image_undo_push_group_layer_convert (GimpImage      *image,
+                                          const gchar    *undo_desc,
+                                          GimpGroupLayer *group)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_GROUP_LAYER (group), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (group)), NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_GROUP_LAYER_UNDO,
+                               GIMP_UNDO_GROUP_LAYER_CONVERT, undo_desc,
+                               GIMP_DIRTY_ITEM | GIMP_DIRTY_DRAWABLE,
+                               "item", group,
+                               NULL);
+}
+
+
+/**********************/
+/*  Text Layer Undos  */
+/**********************/
+
+GimpUndo *
+gimp_image_undo_push_text_layer (GimpImage        *image,
+                                 const gchar      *undo_desc,
+                                 GimpTextLayer    *layer,
+                                 const GParamSpec *pspec)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_TEXT_LAYER (layer), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (layer)), NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_TEXT_UNDO,
+                               GIMP_UNDO_TEXT_LAYER, undo_desc,
+                               GIMP_DIRTY_ITEM | GIMP_DIRTY_DRAWABLE,
+                               "item",  layer,
+                               "param", pspec,
+                               NULL);
+}
+
+GimpUndo *
+gimp_image_undo_push_text_layer_modified (GimpImage     *image,
+                                          const gchar   *undo_desc,
+                                          GimpTextLayer *layer)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_TEXT_LAYER (layer), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (layer)), NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_TEXT_UNDO,
+                               GIMP_UNDO_TEXT_LAYER_MODIFIED, undo_desc,
+                               GIMP_DIRTY_ITEM_META,
+                               "item", layer,
+                               NULL);
+}
+
+GimpUndo *
+gimp_image_undo_push_text_layer_convert (GimpImage     *image,
+                                         const gchar   *undo_desc,
+                                         GimpTextLayer *layer)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_TEXT_LAYER (layer), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (layer)), NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_TEXT_UNDO,
+                               GIMP_UNDO_TEXT_LAYER_CONVERT, undo_desc,
+                               GIMP_DIRTY_ITEM,
+                               "item", layer,
+                               NULL);
+}
+
+
+/**********************/
+/*  Layer Mask Undos  */
+/**********************/
+
+GimpUndo *
+gimp_image_undo_push_layer_mask_add (GimpImage     *image,
+                                     const gchar   *undo_desc,
+                                     GimpLayer     *layer,
+                                     GimpLayerMask *mask)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_LAYER (layer), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (layer)), NULL);
+  g_return_val_if_fail (GIMP_IS_LAYER_MASK (mask), NULL);
+  g_return_val_if_fail (! gimp_item_is_attached (GIMP_ITEM (mask)), NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_LAYER_MASK_UNDO,
+                               GIMP_UNDO_LAYER_MASK_ADD, undo_desc,
+                               GIMP_DIRTY_IMAGE_STRUCTURE,
+                               "item",       layer,
+                               "layer-mask", mask,
+                               NULL);
+}
+
+GimpUndo *
+gimp_image_undo_push_layer_mask_remove (GimpImage     *image,
+                                        const gchar   *undo_desc,
+                                        GimpLayer     *layer,
+                                        GimpLayerMask *mask)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_LAYER (layer), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (layer)), NULL);
+  g_return_val_if_fail (GIMP_IS_LAYER_MASK (mask), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (mask)), NULL);
+  g_return_val_if_fail (gimp_layer_mask_get_layer (mask) == layer, NULL);
+  g_return_val_if_fail (gimp_layer_get_mask (layer) == mask, NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_LAYER_MASK_UNDO,
+                               GIMP_UNDO_LAYER_MASK_REMOVE, undo_desc,
+                               GIMP_DIRTY_IMAGE_STRUCTURE,
+                               "item",       layer,
+                               "layer-mask", mask,
+                               NULL);
+}
+
+GimpUndo *
+gimp_image_undo_push_layer_mask_apply (GimpImage   *image,
+                                       const gchar *undo_desc,
+                                       GimpLayer   *layer)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_LAYER (layer), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (layer)), NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_LAYER_MASK_PROP_UNDO,
+                               GIMP_UNDO_LAYER_MASK_APPLY, undo_desc,
+                               GIMP_DIRTY_ITEM_META,
+                               "item", layer,
+                               NULL);
+}
+
+GimpUndo *
+gimp_image_undo_push_layer_mask_show (GimpImage   *image,
+                                      const gchar *undo_desc,
+                                      GimpLayer   *layer)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_LAYER (layer), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (layer)), NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_LAYER_MASK_PROP_UNDO,
+                               GIMP_UNDO_LAYER_MASK_SHOW, undo_desc,
+                               GIMP_DIRTY_ITEM_META,
+                               "item", layer,
+                               NULL);
+}
+
+
+/*******************/
+/*  Channel Undos  */
+/*******************/
+
+GimpUndo *
+gimp_image_undo_push_channel_add (GimpImage   *image,
+                                  const gchar *undo_desc,
+                                  GimpChannel *channel,
+                                  GimpChannel *prev_channel)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_CHANNEL (channel), NULL);
+  g_return_val_if_fail (! gimp_item_is_attached (GIMP_ITEM (channel)), NULL);
+  g_return_val_if_fail (prev_channel == NULL || GIMP_IS_CHANNEL (prev_channel),
+                        NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_CHANNEL_UNDO,
+                               GIMP_UNDO_CHANNEL_ADD, undo_desc,
+                               GIMP_DIRTY_IMAGE_STRUCTURE,
+                               "item",         channel,
+                               "prev-channel", prev_channel,
+                               NULL);
+}
+
+GimpUndo *
+gimp_image_undo_push_channel_remove (GimpImage   *image,
+                                     const gchar *undo_desc,
+                                     GimpChannel *channel,
+                                     GimpChannel *prev_parent,
+                                     gint         prev_position,
+                                     GimpChannel *prev_channel)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_CHANNEL (channel), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (channel)), NULL);
+  g_return_val_if_fail (prev_parent == NULL || GIMP_IS_CHANNEL (prev_parent),
+                        NULL);
+  g_return_val_if_fail (prev_channel == NULL || GIMP_IS_CHANNEL (prev_channel),
+                        NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_CHANNEL_UNDO,
+                               GIMP_UNDO_CHANNEL_REMOVE, undo_desc,
+                               GIMP_DIRTY_IMAGE_STRUCTURE,
+                               "item",          channel,
+                               "prev-parent",   prev_parent,
+                               "prev-position", prev_position,
+                               "prev-channel",  prev_channel,
+                               NULL);
+}
+
+GimpUndo *
+gimp_image_undo_push_channel_color (GimpImage   *image,
+                                    const gchar *undo_desc,
+                                    GimpChannel *channel)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_CHANNEL (channel), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (channel)), NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_CHANNEL_PROP_UNDO,
+                               GIMP_UNDO_CHANNEL_COLOR, undo_desc,
+                               GIMP_DIRTY_ITEM | GIMP_DIRTY_DRAWABLE,
+                               "item", channel,
+                               NULL);
+}
+
+
+/*******************/
+/*  Vectors Undos  */
+/*******************/
+
+GimpUndo *
+gimp_image_undo_push_vectors_add (GimpImage   *image,
+                                  const gchar *undo_desc,
+                                  GimpVectors *vectors,
+                                  GimpVectors *prev_vectors)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_VECTORS (vectors), NULL);
+  g_return_val_if_fail (! gimp_item_is_attached (GIMP_ITEM (vectors)), NULL);
+  g_return_val_if_fail (prev_vectors == NULL || GIMP_IS_VECTORS (prev_vectors),
+                        NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_VECTORS_UNDO,
+                               GIMP_UNDO_VECTORS_ADD, undo_desc,
+                               GIMP_DIRTY_IMAGE_STRUCTURE,
+                               "item",         vectors,
+                               "prev-vectors", prev_vectors,
+                               NULL);
+}
+
+GimpUndo *
+gimp_image_undo_push_vectors_remove (GimpImage   *image,
+                                     const gchar *undo_desc,
+                                     GimpVectors *vectors,
+                                     GimpVectors *prev_parent,
+                                     gint         prev_position,
+                                     GimpVectors *prev_vectors)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_VECTORS (vectors), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (vectors)), NULL);
+  g_return_val_if_fail (prev_parent == NULL || GIMP_IS_VECTORS (prev_parent),
+                        NULL);
+  g_return_val_if_fail (prev_vectors == NULL || GIMP_IS_VECTORS (prev_vectors),
+                        NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_VECTORS_UNDO,
+                               GIMP_UNDO_VECTORS_REMOVE, undo_desc,
+                               GIMP_DIRTY_IMAGE_STRUCTURE,
+                               "item",          vectors,
+                               "prev-parent",   prev_parent,
+                               "prev-position", prev_position,
+                               "prev-vectors",  prev_vectors,
+                               NULL);
+}
+
+GimpUndo *
+gimp_image_undo_push_vectors_mod (GimpImage   *image,
+                                  const gchar *undo_desc,
+                                  GimpVectors *vectors)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_VECTORS (vectors), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (vectors)), NULL);
+
+  return gimp_image_undo_push (image, GIMP_TYPE_VECTORS_MOD_UNDO,
+                               GIMP_UNDO_VECTORS_MOD, undo_desc,
+                               GIMP_DIRTY_ITEM | GIMP_DIRTY_VECTORS,
+                               "item", vectors,
+                               NULL);
+}
+
+
+/******************************/
+/*  Floating Selection Undos  */
+/******************************/
+
+GimpUndo *
+gimp_image_undo_push_fs_to_layer (GimpImage    *image,
+                                  const gchar  *undo_desc,
+                                  GimpLayer    *floating_layer)
+{
+  GimpUndo *undo;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_LAYER (floating_layer), NULL);
+
+  undo = gimp_image_undo_push (image, GIMP_TYPE_FLOATING_SELECTION_UNDO,
+                               GIMP_UNDO_FS_TO_LAYER, undo_desc,
+                               GIMP_DIRTY_IMAGE_STRUCTURE,
+                               "item", floating_layer,
+                               NULL);
+
+  return undo;
+}
+
+
+/******************************************************************************/
+/*  Something for which programmer is too lazy to write an undo function for  */
+/******************************************************************************/
+
+static void
+undo_pop_cantundo (GimpUndo            *undo,
+                   GimpUndoMode         undo_mode,
+                   GimpUndoAccumulator *accum)
+{
+  switch (undo_mode)
+    {
+    case GIMP_UNDO_MODE_UNDO:
+      gimp_message (undo->image->gimp, NULL, GIMP_MESSAGE_WARNING,
+                    _("Can't undo %s"), gimp_object_get_name (undo));
+      break;
+
+    case GIMP_UNDO_MODE_REDO:
+      break;
+    }
+}
+
+GimpUndo *
+gimp_image_undo_push_cantundo (GimpImage   *image,
+                               const gchar *undo_desc)
+{
+  GimpUndo *undo;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  /* This is the sole purpose of this type of undo: the ability to
+   * mark an image as having been mutated, without really providing
+   * any adequate undo facility.
+   */
+
+  undo = gimp_image_undo_push (image, GIMP_TYPE_UNDO,
+                               GIMP_UNDO_CANT, undo_desc,
+                               GIMP_DIRTY_ALL,
+                               NULL);
+
+  if (undo)
+    g_signal_connect (undo, "pop",
+                      G_CALLBACK (undo_pop_cantundo),
+                      NULL);
+
+  return undo;
+}
diff --git a/app/core/gimpimage-undo-push.h b/app/core/gimpimage-undo-push.h
new file mode 100644
index 0000000..f06fcd8
--- /dev/null
+++ b/app/core/gimpimage-undo-push.h
@@ -0,0 +1,256 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_IMAGE_UNDO_PUSH_H__
+#define __GIMP_IMAGE_UNDO_PUSH_H__
+
+
+/*  image undos  */
+
+GimpUndo * gimp_image_undo_push_image_type          (GimpImage     *image,
+                                                     const gchar   *undo_desc);
+GimpUndo * gimp_image_undo_push_image_precision     (GimpImage     *image,
+                                                     const gchar   *undo_desc);
+GimpUndo * gimp_image_undo_push_image_size          (GimpImage     *image,
+                                                     const gchar   *undo_desc,
+                                                     gint           previous_origin_x,
+                                                     gint           previous_origin_y,
+                                                     gint           previous_width,
+                                                     gint           prevoius_height);
+GimpUndo * gimp_image_undo_push_image_resolution    (GimpImage     *image,
+                                                     const gchar   *undo_desc);
+GimpUndo * gimp_image_undo_push_image_grid          (GimpImage     *image,
+                                                     const gchar   *undo_desc,
+                                                     GimpGrid      *grid);
+GimpUndo * gimp_image_undo_push_image_colormap      (GimpImage     *image,
+                                                     const gchar   *undo_desc);
+GimpUndo * gimp_image_undo_push_image_color_managed (GimpImage     *image,
+                                                     const gchar   *undo_desc);
+GimpUndo * gimp_image_undo_push_image_metadata      (GimpImage     *image,
+                                                     const gchar   *undo_desc);
+GimpUndo * gimp_image_undo_push_image_parasite      (GimpImage     *image,
+                                                     const gchar   *undo_desc,
+                                                     const GimpParasite *parasite);
+GimpUndo * gimp_image_undo_push_image_parasite_remove (GimpImage   *image,
+                                                     const gchar   *undo_desc,
+                                                     const gchar   *name);
+
+
+/*  guide & sample point undos  */
+
+GimpUndo * gimp_image_undo_push_guide               (GimpImage     *image,
+                                                     const gchar   *undo_desc,
+                                                     GimpGuide     *guide);
+GimpUndo * gimp_image_undo_push_sample_point        (GimpImage     *image,
+                                                     const gchar   *undo_desc,
+                                                     GimpSamplePoint *sample_point);
+
+
+/*  drawable undos  */
+
+GimpUndo * gimp_image_undo_push_drawable            (GimpImage     *image,
+                                                     const gchar   *undo_desc,
+                                                     GimpDrawable  *drawable,
+                                                     GeglBuffer    *buffer,
+                                                     gint           x,
+                                                     gint           y);
+GimpUndo * gimp_image_undo_push_drawable_mod        (GimpImage     *image,
+                                                     const gchar   *undo_desc,
+                                                     GimpDrawable  *drawable,
+                                                     gboolean       copy_buffer);
+
+
+/*  mask undos  */
+
+GimpUndo * gimp_image_undo_push_mask                (GimpImage     *image,
+                                                     const gchar   *undo_desc,
+                                                     GimpChannel   *mask);
+GimpUndo * gimp_image_undo_push_mask_precision      (GimpImage     *image,
+                                                     const gchar   *undo_desc,
+                                                     GimpChannel   *mask);
+
+
+/*  item undos  */
+
+GimpUndo * gimp_image_undo_push_item_reorder        (GimpImage     *image,
+                                                     const gchar   *undo_desc,
+                                                     GimpItem      *item);
+GimpUndo * gimp_image_undo_push_item_rename         (GimpImage     *image,
+                                                     const gchar   *undo_desc,
+                                                     GimpItem      *item);
+GimpUndo * gimp_image_undo_push_item_displace       (GimpImage     *image,
+                                                     const gchar   *undo_desc,
+                                                     GimpItem      *item);
+GimpUndo * gimp_image_undo_push_item_visibility     (GimpImage     *image,
+                                                     const gchar   *undo_desc,
+                                                     GimpItem      *item);
+GimpUndo * gimp_image_undo_push_item_linked         (GimpImage     *image,
+                                                     const gchar   *undo_desc,
+                                                     GimpItem      *item);
+GimpUndo * gimp_image_undo_push_item_color_tag      (GimpImage     *image,
+                                                     const gchar   *undo_desc,
+                                                     GimpItem      *item);
+GimpUndo * gimp_image_undo_push_item_lock_content   (GimpImage     *image,
+                                                     const gchar   *undo_desc,
+                                                     GimpItem      *item);
+GimpUndo * gimp_image_undo_push_item_lock_position  (GimpImage     *image,
+                                                     const gchar   *undo_desc,
+                                                     GimpItem      *item);
+GimpUndo * gimp_image_undo_push_item_parasite       (GimpImage     *image,
+                                                     const gchar   *undo_desc,
+                                                     GimpItem      *item,
+                                                     const GimpParasite *parasite);
+GimpUndo * gimp_image_undo_push_item_parasite_remove(GimpImage     *image,
+                                                     const gchar   *undo_desc,
+                                                     GimpItem      *item,
+                                                     const gchar   *name);
+
+
+/*  layer undos  */
+
+GimpUndo * gimp_image_undo_push_layer_add           (GimpImage     *image,
+                                                     const gchar   *undo_desc,
+                                                     GimpLayer     *layer,
+                                                     GimpLayer     *prev_layer);
+GimpUndo * gimp_image_undo_push_layer_remove        (GimpImage     *image,
+                                                     const gchar   *undo_desc,
+                                                     GimpLayer     *layer,
+                                                     GimpLayer     *prev_parent,
+                                                     gint           prev_position,
+                                                     GimpLayer     *prev_layer);
+GimpUndo * gimp_image_undo_push_layer_mode          (GimpImage     *image,
+                                                     const gchar   *undo_desc,
+                                                     GimpLayer     *layer);
+GimpUndo * gimp_image_undo_push_layer_opacity       (GimpImage     *image,
+                                                     const gchar   *undo_desc,
+                                                     GimpLayer     *layer);
+GimpUndo * gimp_image_undo_push_layer_lock_alpha    (GimpImage     *image,
+                                                     const gchar   *undo_desc,
+                                                     GimpLayer     *layer);
+
+
+/*  group layer undos  */
+
+GimpUndo *
+    gimp_image_undo_push_group_layer_suspend_resize (GimpImage      *image,
+                                                     const gchar    *undo_desc,
+                                                     GimpGroupLayer *group);
+GimpUndo *
+     gimp_image_undo_push_group_layer_resume_resize (GimpImage      *image,
+                                                     const gchar    *undo_desc,
+                                                     GimpGroupLayer *group);
+GimpUndo *
+      gimp_image_undo_push_group_layer_suspend_mask (GimpImage      *image,
+                                                     const gchar    *undo_desc,
+                                                     GimpGroupLayer *group);
+GimpUndo *
+       gimp_image_undo_push_group_layer_resume_mask (GimpImage      *image,
+                                                     const gchar    *undo_desc,
+                                                     GimpGroupLayer *group);
+GimpUndo *
+   gimp_image_undo_push_group_layer_start_transform (GimpImage      *image,
+                                                     const gchar    *undo_desc,
+                                                     GimpGroupLayer *group);
+GimpUndo *
+     gimp_image_undo_push_group_layer_end_transform (GimpImage      *image,
+                                                     const gchar    *undo_desc,
+                                                     GimpGroupLayer *group);
+GimpUndo * gimp_image_undo_push_group_layer_convert (GimpImage      *image,
+                                                     const gchar    *undo_desc,
+                                                     GimpGroupLayer *group);
+
+
+/*  text layer undos  */
+
+GimpUndo * gimp_image_undo_push_text_layer          (GimpImage     *image,
+                                                     const gchar   *undo_desc,
+                                                     GimpTextLayer *layer,
+                                                     const GParamSpec *pspec);
+GimpUndo * gimp_image_undo_push_text_layer_modified (GimpImage     *image,
+                                                     const gchar   *undo_desc,
+                                                     GimpTextLayer *layer);
+GimpUndo * gimp_image_undo_push_text_layer_convert  (GimpImage     *image,
+                                                     const gchar   *undo_desc,
+                                                     GimpTextLayer *layer);
+
+
+/*  layer mask undos  */
+
+GimpUndo * gimp_image_undo_push_layer_mask_add      (GimpImage     *image,
+                                                     const gchar   *undo_desc,
+                                                     GimpLayer     *layer,
+                                                     GimpLayerMask *mask);
+GimpUndo * gimp_image_undo_push_layer_mask_remove   (GimpImage     *image,
+                                                     const gchar   *undo_desc,
+                                                     GimpLayer     *layer,
+                                                     GimpLayerMask *mask);
+GimpUndo * gimp_image_undo_push_layer_mask_apply    (GimpImage     *image,
+                                                     const gchar   *undo_desc,
+                                                     GimpLayer     *layer);
+GimpUndo * gimp_image_undo_push_layer_mask_show     (GimpImage     *image,
+                                                     const gchar   *undo_desc,
+                                                     GimpLayer     *layer);
+
+
+/*  channel undos  */
+
+GimpUndo * gimp_image_undo_push_channel_add         (GimpImage     *image,
+                                                     const gchar   *undo_desc,
+                                                     GimpChannel   *channel,
+                                                     GimpChannel   *prev_channel);
+GimpUndo * gimp_image_undo_push_channel_remove      (GimpImage     *image,
+                                                     const gchar   *undo_desc,
+                                                     GimpChannel   *channel,
+                                                     GimpChannel   *prev_parent,
+                                                     gint           prev_position,
+                                                     GimpChannel   *prev_channel);
+GimpUndo * gimp_image_undo_push_channel_color       (GimpImage     *image,
+                                                     const gchar   *undo_desc,
+                                                     GimpChannel   *channel);
+
+
+/*  vectors undos  */
+
+GimpUndo * gimp_image_undo_push_vectors_add         (GimpImage     *image,
+                                                     const gchar   *undo_desc,
+                                                     GimpVectors   *vectors,
+                                                     GimpVectors   *prev_vectors);
+GimpUndo * gimp_image_undo_push_vectors_remove      (GimpImage     *image,
+                                                     const gchar   *undo_desc,
+                                                     GimpVectors   *vectors,
+                                                     GimpVectors   *prev_parent,
+                                                     gint           prev_position,
+                                                     GimpVectors   *prev_vectors);
+GimpUndo * gimp_image_undo_push_vectors_mod         (GimpImage     *image,
+                                                     const gchar   *undo_desc,
+                                                     GimpVectors   *vectors);
+
+
+/*  floating selection undos  */
+
+GimpUndo * gimp_image_undo_push_fs_to_layer         (GimpImage     *image,
+                                                     const gchar   *undo_desc,
+                                                     GimpLayer     *floating_layer);
+
+
+/*  EEK undo  */
+
+GimpUndo * gimp_image_undo_push_cantundo            (GimpImage     *image,
+                                                     const gchar   *undo_desc);
+
+
+#endif  /* __GIMP_IMAGE_UNDO_PUSH_H__ */
diff --git a/app/core/gimpimage-undo.c b/app/core/gimpimage-undo.c
new file mode 100644
index 0000000..fbf808b
--- /dev/null
+++ b/app/core/gimpimage-undo.c
@@ -0,0 +1,695 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "config/gimpcoreconfig.h"
+
+#include "gimp.h"
+#include "gimp-utils.h"
+#include "gimpimage.h"
+#include "gimpimage-private.h"
+#include "gimpimage-undo.h"
+#include "gimpitem.h"
+#include "gimplist.h"
+#include "gimpundostack.h"
+
+
+/*  local function prototypes  */
+
+static void          gimp_image_undo_pop_stack       (GimpImage     *image,
+                                                      GimpUndoStack *undo_stack,
+                                                      GimpUndoStack *redo_stack,
+                                                      GimpUndoMode   undo_mode);
+static void          gimp_image_undo_free_space      (GimpImage     *image);
+static void          gimp_image_undo_free_redo       (GimpImage     *image);
+
+static GimpDirtyMask gimp_image_undo_dirty_from_type (GimpUndoType   undo_type);
+
+
+/*  public functions  */
+
+gboolean
+gimp_image_undo_is_enabled (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+
+  return (GIMP_IMAGE_GET_PRIVATE (image)->undo_freeze_count == 0);
+}
+
+gboolean
+gimp_image_undo_enable (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+
+  /*  Free all undo steps as they are now invalidated  */
+  gimp_image_undo_free (image);
+
+  return gimp_image_undo_thaw (image);
+}
+
+gboolean
+gimp_image_undo_disable (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+
+  return gimp_image_undo_freeze (image);
+}
+
+gboolean
+gimp_image_undo_freeze (GimpImage *image)
+{
+  GimpImagePrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  private->undo_freeze_count++;
+
+  if (private->undo_freeze_count == 1)
+    gimp_image_undo_event (image, GIMP_UNDO_EVENT_UNDO_FREEZE, NULL);
+
+  return TRUE;
+}
+
+gboolean
+gimp_image_undo_thaw (GimpImage *image)
+{
+  GimpImagePrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  g_return_val_if_fail (private->undo_freeze_count > 0, FALSE);
+
+  private->undo_freeze_count--;
+
+  if (private->undo_freeze_count == 0)
+    gimp_image_undo_event (image, GIMP_UNDO_EVENT_UNDO_THAW, NULL);
+
+  return TRUE;
+}
+
+gboolean
+gimp_image_undo (GimpImage *image)
+{
+  GimpImagePrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  g_return_val_if_fail (private->pushing_undo_group == GIMP_UNDO_GROUP_NONE,
+                        FALSE);
+
+  gimp_image_undo_pop_stack (image,
+                             private->undo_stack,
+                             private->redo_stack,
+                             GIMP_UNDO_MODE_UNDO);
+
+  return TRUE;
+}
+
+gboolean
+gimp_image_redo (GimpImage *image)
+{
+  GimpImagePrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  g_return_val_if_fail (private->pushing_undo_group == GIMP_UNDO_GROUP_NONE,
+                        FALSE);
+
+  gimp_image_undo_pop_stack (image,
+                             private->redo_stack,
+                             private->undo_stack,
+                             GIMP_UNDO_MODE_REDO);
+
+  return TRUE;
+}
+
+/*
+ * this function continues to undo as long as it only sees certain
+ * undo types, in particular visibility changes.
+ */
+gboolean
+gimp_image_strong_undo (GimpImage *image)
+{
+  GimpImagePrivate *private;
+  GimpUndo         *undo;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  g_return_val_if_fail (private->pushing_undo_group == GIMP_UNDO_GROUP_NONE,
+                        FALSE);
+
+  undo = gimp_undo_stack_peek (private->undo_stack);
+
+  gimp_image_undo (image);
+
+  while (gimp_undo_is_weak (undo))
+    {
+      undo = gimp_undo_stack_peek (private->undo_stack);
+      if (gimp_undo_is_weak (undo))
+        gimp_image_undo (image);
+    }
+
+  return TRUE;
+}
+
+/*
+ * this function continues to redo as long as it only sees certain
+ * undo types, in particular visibility changes.  Note that the
+ * order of events is set up to make it exactly reverse
+ * gimp_image_strong_undo().
+ */
+gboolean
+gimp_image_strong_redo (GimpImage *image)
+{
+  GimpImagePrivate *private;
+  GimpUndo         *undo;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  g_return_val_if_fail (private->pushing_undo_group == GIMP_UNDO_GROUP_NONE,
+                        FALSE);
+
+  undo = gimp_undo_stack_peek (private->redo_stack);
+
+  gimp_image_redo (image);
+
+  while (gimp_undo_is_weak (undo))
+    {
+      undo = gimp_undo_stack_peek (private->redo_stack);
+      if (gimp_undo_is_weak (undo))
+        gimp_image_redo (image);
+    }
+
+  return TRUE;
+}
+
+GimpUndoStack *
+gimp_image_get_undo_stack (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->undo_stack;
+}
+
+GimpUndoStack *
+gimp_image_get_redo_stack (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->redo_stack;
+}
+
+void
+gimp_image_undo_free (GimpImage *image)
+{
+  GimpImagePrivate *private;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  /*  Emit the UNDO_FREE event before actually freeing everything
+   *  so the views can properly detach from the undo items
+   */
+  gimp_image_undo_event (image, GIMP_UNDO_EVENT_UNDO_FREE, NULL);
+
+  gimp_undo_free (GIMP_UNDO (private->undo_stack), GIMP_UNDO_MODE_UNDO);
+  gimp_undo_free (GIMP_UNDO (private->redo_stack), GIMP_UNDO_MODE_REDO);
+
+  /* If the image was dirty, but could become clean by redo-ing
+   * some actions, then it should now become 'infinitely' dirty.
+   * This is because we've just nuked the actions that would allow
+   * the image to become clean again.
+   */
+  if (private->dirty < 0)
+    private->dirty = 100000;
+
+  /* The same applies to the case where the image would become clean
+   * due to undo actions, but since user can't undo without an undo
+   * stack, that's not so much a problem.
+   */
+}
+
+gint
+gimp_image_get_undo_group_count (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), 0);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->group_count;
+}
+
+gboolean
+gimp_image_undo_group_start (GimpImage    *image,
+                             GimpUndoType  undo_type,
+                             const gchar  *name)
+{
+  GimpImagePrivate *private;
+  GimpUndoStack    *undo_group;
+  GimpDirtyMask     dirty_mask;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+  g_return_val_if_fail (undo_type >  GIMP_UNDO_GROUP_FIRST &&
+                        undo_type <= GIMP_UNDO_GROUP_LAST, FALSE);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  if (! name)
+    name = gimp_undo_type_to_name (undo_type);
+
+  dirty_mask = gimp_image_undo_dirty_from_type (undo_type);
+
+  /* Notify listeners that the image will be modified */
+  if (private->group_count == 0 && dirty_mask != GIMP_DIRTY_NONE)
+    gimp_image_dirty (image, dirty_mask);
+
+  if (private->undo_freeze_count > 0)
+    return FALSE;
+
+  private->group_count++;
+
+  /*  If we're already in a group...ignore  */
+  if (private->group_count > 1)
+    return TRUE;
+
+  /*  nuke the redo stack  */
+  gimp_image_undo_free_redo (image);
+
+  undo_group = gimp_undo_stack_new (image);
+
+  gimp_object_set_name (GIMP_OBJECT (undo_group), name);
+  GIMP_UNDO (undo_group)->undo_type  = undo_type;
+  GIMP_UNDO (undo_group)->dirty_mask = dirty_mask;
+
+  gimp_undo_stack_push_undo (private->undo_stack, GIMP_UNDO (undo_group));
+
+  private->pushing_undo_group = undo_type;
+
+  return TRUE;
+}
+
+gboolean
+gimp_image_undo_group_end (GimpImage *image)
+{
+  GimpImagePrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  if (private->undo_freeze_count > 0)
+    return FALSE;
+
+  g_return_val_if_fail (private->group_count > 0, FALSE);
+
+  private->group_count--;
+
+  if (private->group_count == 0)
+    {
+      private->pushing_undo_group = GIMP_UNDO_GROUP_NONE;
+
+      /* Do it here, since undo_push doesn't emit this event while in
+       * the middle of a group
+       */
+      gimp_image_undo_event (image, GIMP_UNDO_EVENT_UNDO_PUSHED,
+                             gimp_undo_stack_peek (private->undo_stack));
+
+      gimp_image_undo_free_space (image);
+    }
+
+  return TRUE;
+}
+
+GimpUndo *
+gimp_image_undo_push (GimpImage     *image,
+                      GType          object_type,
+                      GimpUndoType   undo_type,
+                      const gchar   *name,
+                      GimpDirtyMask  dirty_mask,
+                      ...)
+{
+  GimpImagePrivate  *private;
+  gint               n_properties = 0;
+  gchar            **names        = NULL;
+  GValue            *values       = NULL;
+  va_list            args;
+  GimpUndo          *undo;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (g_type_is_a (object_type, GIMP_TYPE_UNDO), NULL);
+  g_return_val_if_fail (undo_type > GIMP_UNDO_GROUP_LAST, NULL);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  /* Does this undo dirty the image?  If so, we always want to mark
+   * image dirty, even if we can't actually push the undo.
+   */
+  if (dirty_mask != GIMP_DIRTY_NONE)
+    gimp_image_dirty (image, dirty_mask);
+
+  if (private->undo_freeze_count > 0)
+    return NULL;
+
+  if (! name)
+    name = gimp_undo_type_to_name (undo_type);
+
+  names = gimp_properties_append (object_type,
+                                  &n_properties, names, &values,
+                                  "name",       name,
+                                  "image",      image,
+                                  "undo-type",  undo_type,
+                                  "dirty-mask", dirty_mask,
+                                  NULL);
+
+  va_start (args, dirty_mask);
+  names = gimp_properties_append_valist (object_type,
+                                         &n_properties, names, &values,
+                                         args);
+  va_end (args);
+
+  undo = (GimpUndo *) g_object_new_with_properties (object_type,
+                                                    n_properties,
+                                                    (const gchar **) names,
+                                                    (const GValue *) values);
+
+  gimp_properties_free (n_properties, names, values);
+
+  /*  nuke the redo stack  */
+  gimp_image_undo_free_redo (image);
+
+  if (private->pushing_undo_group == GIMP_UNDO_GROUP_NONE)
+    {
+      gimp_undo_stack_push_undo (private->undo_stack, undo);
+
+      gimp_image_undo_event (image, GIMP_UNDO_EVENT_UNDO_PUSHED, undo);
+
+      gimp_image_undo_free_space (image);
+
+      /*  freeing undo space may have freed the newly pushed undo  */
+      if (gimp_undo_stack_peek (private->undo_stack) == undo)
+        return undo;
+    }
+  else
+    {
+      GimpUndoStack *undo_group;
+
+      undo_group = GIMP_UNDO_STACK (gimp_undo_stack_peek (private->undo_stack));
+
+      gimp_undo_stack_push_undo (undo_group, undo);
+
+      return undo;
+    }
+
+  return NULL;
+}
+
+GimpUndo *
+gimp_image_undo_can_compress (GimpImage    *image,
+                              GType         object_type,
+                              GimpUndoType  undo_type)
+{
+  GimpImagePrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  if (gimp_image_is_dirty (image) &&
+      ! gimp_undo_stack_peek (private->redo_stack))
+    {
+      GimpUndo *undo = gimp_undo_stack_peek (private->undo_stack);
+
+      if (undo && undo->undo_type == undo_type &&
+          g_type_is_a (G_TYPE_FROM_INSTANCE (undo), object_type))
+        {
+          return undo;
+        }
+    }
+
+  return NULL;
+}
+
+
+/*  private functions  */
+
+static void
+gimp_image_undo_pop_stack (GimpImage     *image,
+                           GimpUndoStack *undo_stack,
+                           GimpUndoStack *redo_stack,
+                           GimpUndoMode   undo_mode)
+{
+  GimpUndo            *undo;
+  GimpUndoAccumulator  accum = { 0, };
+
+  g_object_freeze_notify (G_OBJECT (image));
+
+  undo = gimp_undo_stack_pop_undo (undo_stack, undo_mode, &accum);
+
+  if (undo)
+    {
+      if (GIMP_IS_UNDO_STACK (undo))
+        gimp_list_reverse (GIMP_LIST (GIMP_UNDO_STACK (undo)->undos));
+
+      gimp_undo_stack_push_undo (redo_stack, undo);
+
+      if (accum.mode_changed)
+        gimp_image_mode_changed (image);
+
+      if (accum.precision_changed)
+        gimp_image_precision_changed (image);
+
+      if (accum.size_changed)
+        gimp_image_size_changed_detailed (image,
+                                          accum.previous_origin_x,
+                                          accum.previous_origin_y,
+                                          accum.previous_width,
+                                          accum.previous_height);
+
+      if (accum.resolution_changed)
+        gimp_image_resolution_changed (image);
+
+      if (accum.unit_changed)
+        gimp_image_unit_changed (image);
+
+      /* let others know that we just popped an action */
+      gimp_image_undo_event (image,
+                             (undo_mode == GIMP_UNDO_MODE_UNDO) ?
+                             GIMP_UNDO_EVENT_UNDO : GIMP_UNDO_EVENT_REDO,
+                             undo);
+    }
+
+  g_object_thaw_notify (G_OBJECT (image));
+}
+
+static void
+gimp_image_undo_free_space (GimpImage *image)
+{
+  GimpImagePrivate *private = GIMP_IMAGE_GET_PRIVATE (image);
+  GimpContainer    *container;
+  gint              min_undo_levels;
+  gint              max_undo_levels;
+  gint64            undo_size;
+
+  container = private->undo_stack->undos;
+
+  min_undo_levels = image->gimp->config->levels_of_undo;
+  max_undo_levels = 1024; /* FIXME */
+  undo_size       = image->gimp->config->undo_size;
+
+#ifdef DEBUG_IMAGE_UNDO
+  g_printerr ("undo_steps: %d    undo_bytes: %ld\n",
+              gimp_container_get_n_children (container),
+              (glong) gimp_object_get_memsize (GIMP_OBJECT (container), NULL));
+#endif
+
+  /*  keep at least min_undo_levels undo steps  */
+  if (gimp_container_get_n_children (container) <= min_undo_levels)
+    return;
+
+  while ((gimp_object_get_memsize (GIMP_OBJECT (container), NULL) > undo_size) ||
+         (gimp_container_get_n_children (container) > max_undo_levels))
+    {
+      GimpUndo *freed = gimp_undo_stack_free_bottom (private->undo_stack,
+                                                     GIMP_UNDO_MODE_UNDO);
+
+#ifdef DEBUG_IMAGE_UNDO
+      g_printerr ("freed one step: undo_steps: %d    undo_bytes: %ld\n",
+                  gimp_container_get_n_children (container),
+                  (glong) gimp_object_get_memsize (GIMP_OBJECT (container),
+                                                   NULL));
+#endif
+
+      gimp_image_undo_event (image, GIMP_UNDO_EVENT_UNDO_EXPIRED, freed);
+
+      g_object_unref (freed);
+
+      if (gimp_container_get_n_children (container) <= min_undo_levels)
+        return;
+    }
+}
+
+static void
+gimp_image_undo_free_redo (GimpImage *image)
+{
+  GimpImagePrivate *private   = GIMP_IMAGE_GET_PRIVATE (image);
+  GimpContainer    *container = private->redo_stack->undos;
+
+#ifdef DEBUG_IMAGE_UNDO
+  g_printerr ("redo_steps: %d    redo_bytes: %ld\n",
+              gimp_container_get_n_children (container),
+              (glong) gimp_object_get_memsize (GIMP_OBJECT (container), NULL));
+#endif
+
+  if (gimp_container_is_empty (container))
+    return;
+
+  while (gimp_container_get_n_children (container) > 0)
+    {
+      GimpUndo *freed = gimp_undo_stack_free_bottom (private->redo_stack,
+                                                     GIMP_UNDO_MODE_REDO);
+
+#ifdef DEBUG_IMAGE_UNDO
+      g_printerr ("freed one step: redo_steps: %d    redo_bytes: %ld\n",
+                  gimp_container_get_n_children (container),
+                  (glong )gimp_object_get_memsize (GIMP_OBJECT (container),
+                                                   NULL));
+#endif
+
+      gimp_image_undo_event (image, GIMP_UNDO_EVENT_REDO_EXPIRED, freed);
+
+      g_object_unref (freed);
+    }
+
+  /* We need to use <= here because the undo counter has already been
+   * incremented at this point.
+   */
+  if (private->dirty <= 0)
+    {
+      /* If the image was dirty, but could become clean by redo-ing
+       * some actions, then it should now become 'infinitely' dirty.
+       * This is because we've just nuked the actions that would allow
+       * the image to become clean again.
+       */
+      private->dirty = 100000;
+    }
+}
+
+static GimpDirtyMask
+gimp_image_undo_dirty_from_type (GimpUndoType undo_type)
+{
+  switch (undo_type)
+    {
+    case GIMP_UNDO_GROUP_IMAGE_SCALE:
+    case GIMP_UNDO_GROUP_IMAGE_RESIZE:
+    case GIMP_UNDO_GROUP_IMAGE_FLIP:
+    case GIMP_UNDO_GROUP_IMAGE_ROTATE:
+    case GIMP_UNDO_GROUP_IMAGE_TRANSFORM:
+    case GIMP_UNDO_GROUP_IMAGE_CROP:
+      return GIMP_DIRTY_IMAGE | GIMP_DIRTY_IMAGE_SIZE;
+
+    case GIMP_UNDO_GROUP_IMAGE_CONVERT:
+      return GIMP_DIRTY_IMAGE | GIMP_DIRTY_DRAWABLE;
+
+    case GIMP_UNDO_GROUP_IMAGE_LAYERS_MERGE:
+      return GIMP_DIRTY_IMAGE_STRUCTURE | GIMP_DIRTY_DRAWABLE;
+
+    case GIMP_UNDO_GROUP_IMAGE_VECTORS_MERGE:
+      return GIMP_DIRTY_IMAGE_STRUCTURE | GIMP_DIRTY_VECTORS;
+
+    case GIMP_UNDO_GROUP_IMAGE_QUICK_MASK: /* FIXME */
+      return GIMP_DIRTY_IMAGE_STRUCTURE | GIMP_DIRTY_SELECTION;
+
+    case GIMP_UNDO_GROUP_IMAGE_GRID:
+    case GIMP_UNDO_GROUP_GUIDE:
+      return GIMP_DIRTY_IMAGE_META;
+
+    case GIMP_UNDO_GROUP_DRAWABLE:
+    case GIMP_UNDO_GROUP_DRAWABLE_MOD:
+      return GIMP_DIRTY_ITEM | GIMP_DIRTY_DRAWABLE;
+
+    case GIMP_UNDO_GROUP_MASK: /* FIXME */
+      return GIMP_DIRTY_SELECTION;
+
+    case GIMP_UNDO_GROUP_ITEM_VISIBILITY:
+    case GIMP_UNDO_GROUP_ITEM_LINKED:
+    case GIMP_UNDO_GROUP_ITEM_PROPERTIES:
+      return GIMP_DIRTY_ITEM_META;
+
+    case GIMP_UNDO_GROUP_ITEM_DISPLACE: /* FIXME */
+      return GIMP_DIRTY_ITEM | GIMP_DIRTY_DRAWABLE | GIMP_DIRTY_VECTORS;
+
+    case GIMP_UNDO_GROUP_ITEM_SCALE: /* FIXME */
+    case GIMP_UNDO_GROUP_ITEM_RESIZE: /* FIXME */
+      return GIMP_DIRTY_ITEM | GIMP_DIRTY_DRAWABLE | GIMP_DIRTY_VECTORS;
+
+    case GIMP_UNDO_GROUP_LAYER_ADD_MASK:
+    case GIMP_UNDO_GROUP_LAYER_APPLY_MASK:
+      return GIMP_DIRTY_IMAGE_STRUCTURE;
+
+    case GIMP_UNDO_GROUP_FS_TO_LAYER:
+    case GIMP_UNDO_GROUP_FS_FLOAT:
+    case GIMP_UNDO_GROUP_FS_ANCHOR:
+      return GIMP_DIRTY_IMAGE_STRUCTURE;
+
+    case GIMP_UNDO_GROUP_EDIT_PASTE:
+      return GIMP_DIRTY_IMAGE_STRUCTURE;
+
+    case GIMP_UNDO_GROUP_EDIT_CUT:
+      return GIMP_DIRTY_ITEM | GIMP_DIRTY_DRAWABLE;
+
+    case GIMP_UNDO_GROUP_TEXT:
+      return GIMP_DIRTY_ITEM | GIMP_DIRTY_DRAWABLE;
+
+    case GIMP_UNDO_GROUP_TRANSFORM: /* FIXME */
+      return GIMP_DIRTY_ITEM | GIMP_DIRTY_DRAWABLE | GIMP_DIRTY_VECTORS;
+
+    case GIMP_UNDO_GROUP_PAINT:
+      return GIMP_DIRTY_ITEM | GIMP_DIRTY_DRAWABLE;
+
+    case GIMP_UNDO_GROUP_PARASITE_ATTACH:
+    case GIMP_UNDO_GROUP_PARASITE_REMOVE:
+      return GIMP_DIRTY_IMAGE_META | GIMP_DIRTY_ITEM_META;
+
+    case GIMP_UNDO_GROUP_VECTORS_IMPORT:
+      return GIMP_DIRTY_IMAGE_STRUCTURE | GIMP_DIRTY_VECTORS;
+
+    case GIMP_UNDO_GROUP_MISC:
+      return GIMP_DIRTY_ALL;
+
+    default:
+      break;
+    }
+
+  return GIMP_DIRTY_ALL;
+}
diff --git a/app/core/gimpimage-undo.h b/app/core/gimpimage-undo.h
new file mode 100644
index 0000000..34bd2f4
--- /dev/null
+++ b/app/core/gimpimage-undo.h
@@ -0,0 +1,57 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_IMAGE__UNDO_H__
+#define __GIMP_IMAGE__UNDO_H__
+
+
+gboolean        gimp_image_undo_is_enabled      (GimpImage     *image);
+gboolean        gimp_image_undo_enable          (GimpImage     *image);
+gboolean        gimp_image_undo_disable         (GimpImage     *image);
+gboolean        gimp_image_undo_freeze          (GimpImage     *image);
+gboolean        gimp_image_undo_thaw            (GimpImage     *image);
+
+gboolean        gimp_image_undo                 (GimpImage     *image);
+gboolean        gimp_image_redo                 (GimpImage     *image);
+
+gboolean        gimp_image_strong_undo          (GimpImage     *image);
+gboolean        gimp_image_strong_redo          (GimpImage     *image);
+
+GimpUndoStack * gimp_image_get_undo_stack       (GimpImage     *image);
+GimpUndoStack * gimp_image_get_redo_stack       (GimpImage     *image);
+
+void            gimp_image_undo_free            (GimpImage     *image);
+
+gint            gimp_image_get_undo_group_count (GimpImage     *image);
+gboolean        gimp_image_undo_group_start     (GimpImage     *image,
+                                                 GimpUndoType   undo_type,
+                                                 const gchar   *name);
+gboolean        gimp_image_undo_group_end       (GimpImage     *image);
+
+GimpUndo      * gimp_image_undo_push            (GimpImage     *image,
+                                                 GType          object_type,
+                                                 GimpUndoType   undo_type,
+                                                 const gchar   *name,
+                                                 GimpDirtyMask  dirty_mask,
+                                                 ...) G_GNUC_NULL_TERMINATED;
+
+GimpUndo      * gimp_image_undo_can_compress    (GimpImage     *image,
+                                                 GType          object_type,
+                                                 GimpUndoType   undo_type);
+
+
+#endif /* __GIMP_IMAGE__UNDO_H__ */
diff --git a/app/core/gimpimage.c b/app/core/gimpimage.c
new file mode 100644
index 0000000..9908d1b
--- /dev/null
+++ b/app/core/gimpimage.c
@@ -0,0 +1,5191 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+#include <time.h>
+
+#include <cairo.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+#include <gexiv2/gexiv2.h>
+
+#include "libgimpcolor/gimpcolor.h"
+#include "libgimpmath/gimpmath.h"
+#include "libgimpbase/gimpbase.h"
+#include "libgimpconfig/gimpconfig.h"
+
+#include "core-types.h"
+
+#include "config/gimpcoreconfig.h"
+
+#include "operations/layer-modes/gimp-layer-modes.h"
+
+#include "gegl/gimp-babl.h"
+#include "gegl/gimp-gegl-loops.h"
+
+#include "gimp.h"
+#include "gimp-memsize.h"
+#include "gimp-parasites.h"
+#include "gimp-utils.h"
+#include "gimpcontext.h"
+#include "gimpdrawable-floating-selection.h"
+#include "gimpdrawablestack.h"
+#include "gimpgrid.h"
+#include "gimperror.h"
+#include "gimpguide.h"
+#include "gimpidtable.h"
+#include "gimpimage.h"
+#include "gimpimage-color-profile.h"
+#include "gimpimage-colormap.h"
+#include "gimpimage-guides.h"
+#include "gimpimage-item-list.h"
+#include "gimpimage-metadata.h"
+#include "gimpimage-sample-points.h"
+#include "gimpimage-preview.h"
+#include "gimpimage-private.h"
+#include "gimpimage-quick-mask.h"
+#include "gimpimage-symmetry.h"
+#include "gimpimage-undo.h"
+#include "gimpimage-undo-push.h"
+#include "gimpitemtree.h"
+#include "gimplayer.h"
+#include "gimplayer-floating-selection.h"
+#include "gimplayermask.h"
+#include "gimplayerstack.h"
+#include "gimpmarshal.h"
+#include "gimpparasitelist.h"
+#include "gimppickable.h"
+#include "gimpprojectable.h"
+#include "gimpprojection.h"
+#include "gimpsamplepoint.h"
+#include "gimpselection.h"
+#include "gimpsymmetry.h"
+#include "gimptempbuf.h"
+#include "gimptemplate.h"
+#include "gimpundostack.h"
+
+#include "vectors/gimpvectors.h"
+
+#include "gimp-log.h"
+#include "gimp-intl.h"
+
+
+#ifdef DEBUG
+#define TRC(x) g_printerr x
+#else
+#define TRC(x)
+#endif
+
+
+enum
+{
+  MODE_CHANGED,
+  PRECISION_CHANGED,
+  ALPHA_CHANGED,
+  FLOATING_SELECTION_CHANGED,
+  ACTIVE_LAYER_CHANGED,
+  ACTIVE_CHANNEL_CHANGED,
+  ACTIVE_VECTORS_CHANGED,
+  LINKED_ITEMS_CHANGED,
+  COMPONENT_VISIBILITY_CHANGED,
+  COMPONENT_ACTIVE_CHANGED,
+  MASK_CHANGED,
+  RESOLUTION_CHANGED,
+  SIZE_CHANGED_DETAILED,
+  UNIT_CHANGED,
+  QUICK_MASK_CHANGED,
+  SELECTION_INVALIDATE,
+  CLEAN,
+  DIRTY,
+  SAVING,
+  SAVED,
+  EXPORTED,
+  GUIDE_ADDED,
+  GUIDE_REMOVED,
+  GUIDE_MOVED,
+  SAMPLE_POINT_ADDED,
+  SAMPLE_POINT_REMOVED,
+  SAMPLE_POINT_MOVED,
+  PARASITE_ATTACHED,
+  PARASITE_DETACHED,
+  COLORMAP_CHANGED,
+  UNDO_EVENT,
+  LAST_SIGNAL
+};
+
+enum
+{
+  PROP_0,
+  PROP_GIMP,
+  PROP_ID,
+  PROP_WIDTH,
+  PROP_HEIGHT,
+  PROP_BASE_TYPE,
+  PROP_PRECISION,
+  PROP_METADATA,
+  PROP_BUFFER,
+  PROP_SYMMETRY,
+  PROP_CONVERTING,
+};
+
+
+/*  local function prototypes  */
+
+static void     gimp_color_managed_iface_init    (GimpColorManagedInterface *iface);
+static void     gimp_projectable_iface_init      (GimpProjectableInterface  *iface);
+static void     gimp_pickable_iface_init         (GimpPickableInterface     *iface);
+
+static void     gimp_image_constructed           (GObject           *object);
+static void     gimp_image_set_property          (GObject           *object,
+                                                  guint              property_id,
+                                                  const GValue      *value,
+                                                  GParamSpec        *pspec);
+static void     gimp_image_get_property          (GObject           *object,
+                                                  guint              property_id,
+                                                  GValue            *value,
+                                                  GParamSpec        *pspec);
+static void     gimp_image_dispose               (GObject           *object);
+static void     gimp_image_finalize              (GObject           *object);
+
+static void     gimp_image_name_changed          (GimpObject        *object);
+static gint64   gimp_image_get_memsize           (GimpObject        *object,
+                                                  gint64            *gui_size);
+
+static gboolean gimp_image_get_size              (GimpViewable      *viewable,
+                                                  gint              *width,
+                                                  gint              *height);
+static void     gimp_image_size_changed          (GimpViewable      *viewable);
+static gchar  * gimp_image_get_description       (GimpViewable      *viewable,
+                                                  gchar            **tooltip);
+
+static void     gimp_image_real_mode_changed     (GimpImage         *image);
+static void     gimp_image_real_precision_changed(GimpImage         *image);
+static void     gimp_image_real_resolution_changed(GimpImage        *image);
+static void     gimp_image_real_size_changed_detailed
+                                                 (GimpImage         *image,
+                                                  gint               previous_origin_x,
+                                                  gint               previous_origin_y,
+                                                  gint               previous_width,
+                                                  gint               previous_height);
+static void     gimp_image_real_unit_changed     (GimpImage         *image);
+static void     gimp_image_real_colormap_changed (GimpImage         *image,
+                                                  gint               color_index);
+
+static const guint8 *
+        gimp_image_color_managed_get_icc_profile (GimpColorManaged  *managed,
+                                                  gsize             *len);
+static GimpColorProfile *
+      gimp_image_color_managed_get_color_profile (GimpColorManaged  *managed);
+static void
+        gimp_image_color_managed_profile_changed (GimpColorManaged  *managed);
+
+static void        gimp_image_projectable_flush  (GimpProjectable   *projectable,
+                                                  gboolean           invalidate_preview);
+static GeglRectangle gimp_image_get_bounding_box (GimpProjectable   *projectable);
+static GeglNode   * gimp_image_get_graph         (GimpProjectable   *projectable);
+static GimpImage  * gimp_image_get_image         (GimpProjectable   *projectable);
+static const Babl * gimp_image_get_proj_format   (GimpProjectable   *projectable);
+
+static void         gimp_image_pickable_flush    (GimpPickable      *pickable);
+static GeglBuffer * gimp_image_get_buffer        (GimpPickable      *pickable);
+static gboolean     gimp_image_get_pixel_at      (GimpPickable      *pickable,
+                                                  gint               x,
+                                                  gint               y,
+                                                  const Babl        *format,
+                                                  gpointer           pixel);
+static gdouble      gimp_image_get_opacity_at    (GimpPickable      *pickable,
+                                                  gint               x,
+                                                  gint               y);
+static void         gimp_image_get_pixel_average (GimpPickable      *pickable,
+                                                  const GeglRectangle *rect,
+                                                  const Babl        *format,
+                                                  gpointer           pixel);
+static void         gimp_image_pixel_to_srgb     (GimpPickable      *pickable,
+                                                  const Babl        *format,
+                                                  gpointer           pixel,
+                                                  GimpRGB           *color);
+static void         gimp_image_srgb_to_pixel     (GimpPickable      *pickable,
+                                                  const GimpRGB     *color,
+                                                  const Babl        *format,
+                                                  gpointer           pixel);
+
+static void     gimp_image_projection_buffer_notify
+                                                 (GimpProjection    *projection,
+                                                  const GParamSpec  *pspec,
+                                                  GimpImage         *image);
+static void     gimp_image_mask_update           (GimpDrawable      *drawable,
+                                                  gint               x,
+                                                  gint               y,
+                                                  gint               width,
+                                                  gint               height,
+                                                  GimpImage         *image);
+static void     gimp_image_layers_changed        (GimpContainer     *container,
+                                                  GimpChannel       *channel,
+                                                  GimpImage         *image);
+static void     gimp_image_layer_offset_changed  (GimpDrawable      *drawable,
+                                                  const GParamSpec  *pspec,
+                                                  GimpImage         *image);
+static void     gimp_image_layer_bounding_box_changed
+                                                 (GimpDrawable      *drawable,
+                                                  GimpImage         *image);
+static void     gimp_image_layer_alpha_changed   (GimpDrawable      *drawable,
+                                                  GimpImage         *image);
+static void     gimp_image_channel_add           (GimpContainer     *container,
+                                                  GimpChannel       *channel,
+                                                  GimpImage         *image);
+static void     gimp_image_channel_remove        (GimpContainer     *container,
+                                                  GimpChannel       *channel,
+                                                  GimpImage         *image);
+static void     gimp_image_channel_name_changed  (GimpChannel       *channel,
+                                                  GimpImage         *image);
+static void     gimp_image_channel_color_changed (GimpChannel       *channel,
+                                                  GimpImage         *image);
+static void     gimp_image_active_layer_notify   (GimpItemTree      *tree,
+                                                  const GParamSpec  *pspec,
+                                                  GimpImage         *image);
+static void     gimp_image_active_channel_notify (GimpItemTree      *tree,
+                                                  const GParamSpec  *pspec,
+                                                  GimpImage         *image);
+static void     gimp_image_active_vectors_notify (GimpItemTree      *tree,
+                                                  const GParamSpec  *pspec,
+                                                  GimpImage         *image);
+
+static void     gimp_image_freeze_bounding_box   (GimpImage         *image);
+static void     gimp_image_thaw_bounding_box     (GimpImage         *image);
+static void     gimp_image_update_bounding_box   (GimpImage         *image);
+
+
+G_DEFINE_TYPE_WITH_CODE (GimpImage, gimp_image, GIMP_TYPE_VIEWABLE,
+                         G_ADD_PRIVATE (GimpImage)
+                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_COLOR_MANAGED,
+                                                gimp_color_managed_iface_init)
+                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_PROJECTABLE,
+                                                gimp_projectable_iface_init)
+                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_PICKABLE,
+                                                gimp_pickable_iface_init))
+
+#define parent_class gimp_image_parent_class
+
+static guint gimp_image_signals[LAST_SIGNAL] = { 0 };
+
+
+static void
+gimp_image_class_init (GimpImageClass *klass)
+{
+  GObjectClass      *object_class      = G_OBJECT_CLASS (klass);
+  GimpObjectClass   *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+  GimpViewableClass *viewable_class    = GIMP_VIEWABLE_CLASS (klass);
+
+  gimp_image_signals[MODE_CHANGED] =
+    g_signal_new ("mode-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpImageClass, mode_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  gimp_image_signals[PRECISION_CHANGED] =
+    g_signal_new ("precision-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpImageClass, precision_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  gimp_image_signals[ALPHA_CHANGED] =
+    g_signal_new ("alpha-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpImageClass, alpha_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  gimp_image_signals[FLOATING_SELECTION_CHANGED] =
+    g_signal_new ("floating-selection-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpImageClass, floating_selection_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  gimp_image_signals[ACTIVE_LAYER_CHANGED] =
+    g_signal_new ("active-layer-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpImageClass, active_layer_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  gimp_image_signals[ACTIVE_CHANNEL_CHANGED] =
+    g_signal_new ("active-channel-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpImageClass, active_channel_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  gimp_image_signals[ACTIVE_VECTORS_CHANGED] =
+    g_signal_new ("active-vectors-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpImageClass, active_vectors_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  gimp_image_signals[LINKED_ITEMS_CHANGED] =
+    g_signal_new ("linked-items-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpImageClass, linked_items_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  gimp_image_signals[COMPONENT_VISIBILITY_CHANGED] =
+    g_signal_new ("component-visibility-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpImageClass, component_visibility_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__ENUM,
+                  G_TYPE_NONE, 1,
+                  GIMP_TYPE_CHANNEL_TYPE);
+
+  gimp_image_signals[COMPONENT_ACTIVE_CHANGED] =
+    g_signal_new ("component-active-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpImageClass, component_active_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__ENUM,
+                  G_TYPE_NONE, 1,
+                  GIMP_TYPE_CHANNEL_TYPE);
+
+  gimp_image_signals[MASK_CHANGED] =
+    g_signal_new ("mask-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpImageClass, mask_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  gimp_image_signals[RESOLUTION_CHANGED] =
+    g_signal_new ("resolution-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpImageClass, resolution_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  gimp_image_signals[SIZE_CHANGED_DETAILED] =
+    g_signal_new ("size-changed-detailed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpImageClass, size_changed_detailed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__INT_INT_INT_INT,
+                  G_TYPE_NONE, 4,
+                  G_TYPE_INT,
+                  G_TYPE_INT,
+                  G_TYPE_INT,
+                  G_TYPE_INT);
+
+  gimp_image_signals[UNIT_CHANGED] =
+    g_signal_new ("unit-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpImageClass, unit_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  gimp_image_signals[QUICK_MASK_CHANGED] =
+    g_signal_new ("quick-mask-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpImageClass, quick_mask_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  gimp_image_signals[SELECTION_INVALIDATE] =
+    g_signal_new ("selection-invalidate",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpImageClass, selection_invalidate),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  gimp_image_signals[CLEAN] =
+    g_signal_new ("clean",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpImageClass, clean),
+                  NULL, NULL,
+                  gimp_marshal_VOID__FLAGS,
+                  G_TYPE_NONE, 1,
+                  GIMP_TYPE_DIRTY_MASK);
+
+  gimp_image_signals[DIRTY] =
+    g_signal_new ("dirty",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpImageClass, dirty),
+                  NULL, NULL,
+                  gimp_marshal_VOID__FLAGS,
+                  G_TYPE_NONE, 1,
+                  GIMP_TYPE_DIRTY_MASK);
+
+  gimp_image_signals[SAVING] =
+    g_signal_new ("saving",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpImageClass, saving),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  gimp_image_signals[SAVED] =
+    g_signal_new ("saved",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpImageClass, saved),
+                  NULL, NULL,
+                  gimp_marshal_VOID__OBJECT,
+                  G_TYPE_NONE, 1,
+                  G_TYPE_FILE);
+
+  gimp_image_signals[EXPORTED] =
+    g_signal_new ("exported",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpImageClass, exported),
+                  NULL, NULL,
+                  gimp_marshal_VOID__OBJECT,
+                  G_TYPE_NONE, 1,
+                  G_TYPE_FILE);
+
+  gimp_image_signals[GUIDE_ADDED] =
+    g_signal_new ("guide-added",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpImageClass, guide_added),
+                  NULL, NULL,
+                  gimp_marshal_VOID__OBJECT,
+                  G_TYPE_NONE, 1,
+                  GIMP_TYPE_GUIDE);
+
+  gimp_image_signals[GUIDE_REMOVED] =
+    g_signal_new ("guide-removed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpImageClass, guide_removed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__OBJECT,
+                  G_TYPE_NONE, 1,
+                  GIMP_TYPE_GUIDE);
+
+  gimp_image_signals[GUIDE_MOVED] =
+    g_signal_new ("guide-moved",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpImageClass, guide_moved),
+                  NULL, NULL,
+                  gimp_marshal_VOID__OBJECT,
+                  G_TYPE_NONE, 1,
+                  GIMP_TYPE_GUIDE);
+
+  gimp_image_signals[SAMPLE_POINT_ADDED] =
+    g_signal_new ("sample-point-added",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpImageClass, sample_point_added),
+                  NULL, NULL,
+                  gimp_marshal_VOID__OBJECT,
+                  G_TYPE_NONE, 1,
+                  GIMP_TYPE_SAMPLE_POINT);
+
+  gimp_image_signals[SAMPLE_POINT_REMOVED] =
+    g_signal_new ("sample-point-removed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpImageClass, sample_point_removed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__OBJECT,
+                  G_TYPE_NONE, 1,
+                  GIMP_TYPE_SAMPLE_POINT);
+
+  gimp_image_signals[SAMPLE_POINT_MOVED] =
+    g_signal_new ("sample-point-moved",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpImageClass, sample_point_moved),
+                  NULL, NULL,
+                  gimp_marshal_VOID__OBJECT,
+                  G_TYPE_NONE, 1,
+                  GIMP_TYPE_SAMPLE_POINT);
+
+  gimp_image_signals[PARASITE_ATTACHED] =
+    g_signal_new ("parasite-attached",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpImageClass, parasite_attached),
+                  NULL, NULL,
+                  g_cclosure_marshal_VOID__STRING,
+                  G_TYPE_NONE, 1,
+                  G_TYPE_STRING);
+
+  gimp_image_signals[PARASITE_DETACHED] =
+    g_signal_new ("parasite-detached",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpImageClass, parasite_detached),
+                  NULL, NULL,
+                  g_cclosure_marshal_VOID__STRING,
+                  G_TYPE_NONE, 1,
+                  G_TYPE_STRING);
+
+  gimp_image_signals[COLORMAP_CHANGED] =
+    g_signal_new ("colormap-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpImageClass, colormap_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__INT,
+                  G_TYPE_NONE, 1,
+                  G_TYPE_INT);
+
+  gimp_image_signals[UNDO_EVENT] =
+    g_signal_new ("undo-event",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpImageClass, undo_event),
+                  NULL, NULL,
+                  gimp_marshal_VOID__ENUM_OBJECT,
+                  G_TYPE_NONE, 2,
+                  GIMP_TYPE_UNDO_EVENT,
+                  GIMP_TYPE_UNDO);
+
+  object_class->constructed           = gimp_image_constructed;
+  object_class->set_property          = gimp_image_set_property;
+  object_class->get_property          = gimp_image_get_property;
+  object_class->dispose               = gimp_image_dispose;
+  object_class->finalize              = gimp_image_finalize;
+
+  gimp_object_class->name_changed     = gimp_image_name_changed;
+  gimp_object_class->get_memsize      = gimp_image_get_memsize;
+
+  viewable_class->default_icon_name   = "gimp-image";
+  viewable_class->get_size            = gimp_image_get_size;
+  viewable_class->size_changed        = gimp_image_size_changed;
+  viewable_class->get_preview_size    = gimp_image_get_preview_size;
+  viewable_class->get_popup_size      = gimp_image_get_popup_size;
+  viewable_class->get_new_preview     = gimp_image_get_new_preview;
+  viewable_class->get_new_pixbuf      = gimp_image_get_new_pixbuf;
+  viewable_class->get_description     = gimp_image_get_description;
+
+  klass->mode_changed                 = gimp_image_real_mode_changed;
+  klass->precision_changed            = gimp_image_real_precision_changed;
+  klass->alpha_changed                = NULL;
+  klass->floating_selection_changed   = NULL;
+  klass->active_layer_changed         = NULL;
+  klass->active_channel_changed       = NULL;
+  klass->active_vectors_changed       = NULL;
+  klass->linked_items_changed         = NULL;
+  klass->component_visibility_changed = NULL;
+  klass->component_active_changed     = NULL;
+  klass->mask_changed                 = NULL;
+  klass->resolution_changed           = gimp_image_real_resolution_changed;
+  klass->size_changed_detailed        = gimp_image_real_size_changed_detailed;
+  klass->unit_changed                 = gimp_image_real_unit_changed;
+  klass->quick_mask_changed           = NULL;
+  klass->selection_invalidate         = NULL;
+
+  klass->clean                        = NULL;
+  klass->dirty                        = NULL;
+  klass->saving                       = NULL;
+  klass->saved                        = NULL;
+  klass->exported                     = NULL;
+  klass->guide_added                  = NULL;
+  klass->guide_removed                = NULL;
+  klass->guide_moved                  = NULL;
+  klass->sample_point_added           = NULL;
+  klass->sample_point_removed         = NULL;
+  klass->sample_point_moved           = NULL;
+  klass->parasite_attached            = NULL;
+  klass->parasite_detached            = NULL;
+  klass->colormap_changed             = gimp_image_real_colormap_changed;
+  klass->undo_event                   = NULL;
+
+  g_object_class_install_property (object_class, PROP_GIMP,
+                                   g_param_spec_object ("gimp", NULL, NULL,
+                                                        GIMP_TYPE_GIMP,
+                                                        GIMP_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT_ONLY));
+
+  g_object_class_install_property (object_class, PROP_ID,
+                                   g_param_spec_int ("id", NULL, NULL,
+                                                     0, G_MAXINT, 0,
+                                                     GIMP_PARAM_READABLE));
+
+  g_object_class_install_property (object_class, PROP_WIDTH,
+                                   g_param_spec_int ("width", NULL, NULL,
+                                                     1, GIMP_MAX_IMAGE_SIZE, 1,
+                                                     GIMP_PARAM_READWRITE |
+                                                     G_PARAM_CONSTRUCT));
+
+  g_object_class_install_property (object_class, PROP_HEIGHT,
+                                   g_param_spec_int ("height", NULL, NULL,
+                                                     1, GIMP_MAX_IMAGE_SIZE, 1,
+                                                     GIMP_PARAM_READWRITE |
+                                                     G_PARAM_CONSTRUCT));
+
+  g_object_class_install_property (object_class, PROP_BASE_TYPE,
+                                   g_param_spec_enum ("base-type", NULL, NULL,
+                                                      GIMP_TYPE_IMAGE_BASE_TYPE,
+                                                      GIMP_RGB,
+                                                      GIMP_PARAM_READWRITE |
+                                                      G_PARAM_CONSTRUCT));
+
+  g_object_class_install_property (object_class, PROP_PRECISION,
+                                   g_param_spec_enum ("precision", NULL, NULL,
+                                                      GIMP_TYPE_PRECISION,
+                                                      GIMP_PRECISION_U8_GAMMA,
+                                                      GIMP_PARAM_READWRITE |
+                                                      G_PARAM_CONSTRUCT));
+
+  g_object_class_install_property (object_class, PROP_METADATA,
+                                   g_param_spec_object ("metadata", NULL, NULL,
+                                                        GEXIV2_TYPE_METADATA,
+                                                        GIMP_PARAM_READABLE));
+
+  g_object_class_override_property (object_class, PROP_BUFFER, "buffer");
+
+  g_object_class_install_property (object_class, PROP_SYMMETRY,
+                                   g_param_spec_gtype ("symmetry",
+                                                       NULL, _("Symmetry"),
+                                                       GIMP_TYPE_SYMMETRY,
+                                                       GIMP_PARAM_READWRITE |
+                                                       G_PARAM_CONSTRUCT));
+
+  g_object_class_install_property (object_class, PROP_CONVERTING,
+                                   g_param_spec_boolean ("converting",
+                                                         NULL, NULL,
+                                                         FALSE,
+                                                         GIMP_PARAM_READWRITE));
+}
+
+static void
+gimp_color_managed_iface_init (GimpColorManagedInterface *iface)
+{
+  iface->get_icc_profile   = gimp_image_color_managed_get_icc_profile;
+  iface->get_color_profile = gimp_image_color_managed_get_color_profile;
+  iface->profile_changed   = gimp_image_color_managed_profile_changed;
+}
+
+static void
+gimp_projectable_iface_init (GimpProjectableInterface *iface)
+{
+  iface->flush              = gimp_image_projectable_flush;
+  iface->get_image          = gimp_image_get_image;
+  iface->get_format         = gimp_image_get_proj_format;
+  iface->get_bounding_box   = gimp_image_get_bounding_box;
+  iface->get_graph          = gimp_image_get_graph;
+  iface->invalidate_preview = (void (*) (GimpProjectable*)) gimp_viewable_invalidate_preview;
+}
+
+static void
+gimp_pickable_iface_init (GimpPickableInterface *iface)
+{
+  iface->flush                 = gimp_image_pickable_flush;
+  iface->get_image             = (GimpImage  * (*) (GimpPickable *pickable)) gimp_image_get_image;
+  iface->get_format            = (const Babl * (*) (GimpPickable *pickable)) gimp_image_get_proj_format;
+  iface->get_format_with_alpha = (const Babl * (*) (GimpPickable *pickable)) gimp_image_get_proj_format;
+  iface->get_buffer            = gimp_image_get_buffer;
+  iface->get_pixel_at          = gimp_image_get_pixel_at;
+  iface->get_opacity_at        = gimp_image_get_opacity_at;
+  iface->get_pixel_average     = gimp_image_get_pixel_average;
+  iface->pixel_to_srgb         = gimp_image_pixel_to_srgb;
+  iface->srgb_to_pixel         = gimp_image_srgb_to_pixel;
+}
+
+static void
+gimp_image_init (GimpImage *image)
+{
+  GimpImagePrivate *private = gimp_image_get_instance_private (image);
+  gint              i;
+
+  image->priv = private;
+
+  private->ID                  = 0;
+
+  private->load_proc           = NULL;
+  private->save_proc           = NULL;
+
+  private->width               = 0;
+  private->height              = 0;
+  private->xresolution         = 1.0;
+  private->yresolution         = 1.0;
+  private->resolution_set      = FALSE;
+  private->resolution_unit     = GIMP_UNIT_INCH;
+  private->base_type           = GIMP_RGB;
+  private->precision           = GIMP_PRECISION_U8_GAMMA;
+  private->new_layer_mode      = -1;
+
+  private->show_all            = 0;
+  private->bounding_box.x      = 0;
+  private->bounding_box.y      = 0;
+  private->bounding_box.width  = 0;
+  private->bounding_box.height = 0;
+  private->pickable_buffer     = NULL;
+
+  private->colormap            = NULL;
+  private->n_colors            = 0;
+  private->palette             = NULL;
+
+  private->is_color_managed    = TRUE;
+
+  private->metadata            = NULL;
+
+  private->dirty               = 1;
+  private->dirty_time          = 0;
+  private->undo_freeze_count   = 0;
+
+  private->export_dirty        = 1;
+
+  private->instance_count      = 0;
+  private->disp_count          = 0;
+
+  private->tattoo_state        = 0;
+
+  private->projection          = gimp_projection_new (GIMP_PROJECTABLE (image));
+
+  private->symmetries          = NULL;
+  private->active_symmetry     = NULL;
+
+  private->guides              = NULL;
+  private->grid                = NULL;
+  private->sample_points       = NULL;
+
+  private->layers              = gimp_item_tree_new (image,
+                                                     GIMP_TYPE_LAYER_STACK,
+                                                     GIMP_TYPE_LAYER);
+  private->channels            = gimp_item_tree_new (image,
+                                                     GIMP_TYPE_DRAWABLE_STACK,
+                                                     GIMP_TYPE_CHANNEL);
+  private->vectors             = gimp_item_tree_new (image,
+                                                     GIMP_TYPE_ITEM_STACK,
+                                                     GIMP_TYPE_VECTORS);
+  private->layer_stack         = NULL;
+
+  g_signal_connect (private->projection, "notify::buffer",
+                    G_CALLBACK (gimp_image_projection_buffer_notify),
+                    image);
+
+  g_signal_connect (private->layers, "notify::active-item",
+                    G_CALLBACK (gimp_image_active_layer_notify),
+                    image);
+  g_signal_connect (private->channels, "notify::active-item",
+                    G_CALLBACK (gimp_image_active_channel_notify),
+                    image);
+  g_signal_connect (private->vectors, "notify::active-item",
+                    G_CALLBACK (gimp_image_active_vectors_notify),
+                    image);
+
+  g_signal_connect_swapped (private->layers->container, "update",
+                            G_CALLBACK (gimp_image_invalidate),
+                            image);
+
+  private->layer_offset_x_handler =
+    gimp_container_add_handler (private->layers->container, "notify::offset-x",
+                                G_CALLBACK (gimp_image_layer_offset_changed),
+                                image);
+  private->layer_offset_y_handler =
+    gimp_container_add_handler (private->layers->container, "notify::offset-y",
+                                G_CALLBACK (gimp_image_layer_offset_changed),
+                                image);
+  private->layer_bounding_box_handler =
+    gimp_container_add_handler (private->layers->container, "bounding-box-changed",
+                                G_CALLBACK (gimp_image_layer_bounding_box_changed),
+                                image);
+  private->layer_alpha_handler =
+    gimp_container_add_handler (private->layers->container, "alpha-changed",
+                                G_CALLBACK (gimp_image_layer_alpha_changed),
+                                image);
+
+  g_signal_connect (private->layers->container, "add",
+                    G_CALLBACK (gimp_image_layers_changed),
+                    image);
+  g_signal_connect (private->layers->container, "remove",
+                    G_CALLBACK (gimp_image_layers_changed),
+                    image);
+
+  g_signal_connect_swapped (private->channels->container, "update",
+                            G_CALLBACK (gimp_image_invalidate),
+                            image);
+
+  private->channel_name_changed_handler =
+    gimp_container_add_handler (private->channels->container, "name-changed",
+                                G_CALLBACK (gimp_image_channel_name_changed),
+                                image);
+  private->channel_color_changed_handler =
+    gimp_container_add_handler (private->channels->container, "color-changed",
+                                G_CALLBACK (gimp_image_channel_color_changed),
+                                image);
+
+  g_signal_connect (private->channels->container, "add",
+                    G_CALLBACK (gimp_image_channel_add),
+                    image);
+  g_signal_connect (private->channels->container, "remove",
+                    G_CALLBACK (gimp_image_channel_remove),
+                    image);
+
+  private->floating_sel        = NULL;
+  private->selection_mask      = NULL;
+
+  private->parasites           = gimp_parasite_list_new ();
+
+  for (i = 0; i < MAX_CHANNELS; i++)
+    {
+      private->visible[i] = TRUE;
+      private->active[i]  = TRUE;
+    }
+
+  private->quick_mask_state    = FALSE;
+  private->quick_mask_inverted = FALSE;
+  gimp_rgba_set (&private->quick_mask_color, 1.0, 0.0, 0.0, 0.5);
+
+  private->undo_stack          = gimp_undo_stack_new (image);
+  private->redo_stack          = gimp_undo_stack_new (image);
+  private->group_count         = 0;
+  private->pushing_undo_group  = GIMP_UNDO_GROUP_NONE;
+
+  private->flush_accum.alpha_changed              = FALSE;
+  private->flush_accum.mask_changed               = FALSE;
+  private->flush_accum.floating_selection_changed = FALSE;
+  private->flush_accum.preview_invalidated        = FALSE;
+}
+
+static void
+gimp_image_constructed (GObject *object)
+{
+  GimpImage        *image   = GIMP_IMAGE (object);
+  GimpImagePrivate *private = GIMP_IMAGE_GET_PRIVATE (image);
+  GimpChannel      *selection;
+  GimpCoreConfig   *config;
+  GimpTemplate     *template;
+
+  G_OBJECT_CLASS (parent_class)->constructed (object);
+
+  gimp_assert (GIMP_IS_GIMP (image->gimp));
+
+  config = image->gimp->config;
+
+  private->ID = gimp_id_table_insert (image->gimp->image_table, image);
+
+  template = config->default_image;
+
+  private->xresolution     = gimp_template_get_resolution_x (template);
+  private->yresolution     = gimp_template_get_resolution_y (template);
+  private->resolution_unit = gimp_template_get_resolution_unit (template);
+
+  private->grid = gimp_config_duplicate (GIMP_CONFIG (config->default_grid));
+
+  private->quick_mask_color = config->quick_mask_color;
+
+  gimp_image_update_bounding_box (image);
+
+  if (private->base_type == GIMP_INDEXED)
+    gimp_image_colormap_init (image);
+
+  selection = gimp_selection_new (image,
+                                  gimp_image_get_width  (image),
+                                  gimp_image_get_height (image));
+  gimp_image_take_mask (image, selection);
+
+  g_signal_connect_object (config, "notify::transparency-type",
+                           G_CALLBACK (gimp_item_stack_invalidate_previews),
+                           private->layers->container, G_CONNECT_SWAPPED);
+  g_signal_connect_object (config, "notify::transparency-size",
+                           G_CALLBACK (gimp_item_stack_invalidate_previews),
+                           private->layers->container, G_CONNECT_SWAPPED);
+  g_signal_connect_object (config, "notify::layer-previews",
+                           G_CALLBACK (gimp_viewable_size_changed),
+                           image, G_CONNECT_SWAPPED);
+  g_signal_connect_object (config, "notify::group-layer-previews",
+                           G_CALLBACK (gimp_viewable_size_changed),
+                           image, G_CONNECT_SWAPPED);
+
+  gimp_container_add (image->gimp->images, GIMP_OBJECT (image));
+}
+
+static void
+gimp_image_set_property (GObject      *object,
+                         guint         property_id,
+                         const GValue *value,
+                         GParamSpec   *pspec)
+{
+  GimpImage        *image   = GIMP_IMAGE (object);
+  GimpImagePrivate *private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  switch (property_id)
+    {
+    case PROP_GIMP:
+      image->gimp = g_value_get_object (value);
+      break;
+
+    case PROP_WIDTH:
+      private->width = g_value_get_int (value);
+      break;
+    case PROP_HEIGHT:
+      private->height = g_value_get_int (value);
+      break;
+
+    case PROP_BASE_TYPE:
+      private->base_type = g_value_get_enum (value);
+      _gimp_image_free_color_transforms (image);
+      break;
+
+    case PROP_PRECISION:
+      private->precision = g_value_get_enum (value);
+      _gimp_image_free_color_transforms (image);
+      break;
+
+    case PROP_SYMMETRY:
+      {
+        GList *iter;
+        GType  type = g_value_get_gtype (value);
+
+        if (private->active_symmetry)
+          g_object_set (private->active_symmetry,
+                        "active", FALSE,
+                        NULL);
+        private->active_symmetry = NULL;
+
+        for (iter = private->symmetries; iter; iter = g_list_next (iter))
+          {
+            GimpSymmetry *sym = iter->data;
+
+            if (type == G_TYPE_FROM_INSTANCE (sym))
+              private->active_symmetry = iter->data;
+          }
+
+        if (! private->active_symmetry &&
+            g_type_is_a (type, GIMP_TYPE_SYMMETRY))
+          {
+            GimpSymmetry *sym = gimp_image_symmetry_new (image, type);
+
+            gimp_image_symmetry_add (image, sym);
+            g_object_unref (sym);
+
+            private->active_symmetry = sym;
+          }
+
+        if (private->active_symmetry)
+          g_object_set (private->active_symmetry,
+                        "active", TRUE,
+                        NULL);
+      }
+      break;
+
+    case PROP_CONVERTING:
+      private->converting = g_value_get_boolean (value);
+      break;
+
+    case PROP_ID:
+    case PROP_METADATA:
+    case PROP_BUFFER:
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_image_get_property (GObject    *object,
+                         guint       property_id,
+                         GValue     *value,
+                         GParamSpec *pspec)
+{
+  GimpImage        *image   = GIMP_IMAGE (object);
+  GimpImagePrivate *private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  switch (property_id)
+    {
+    case PROP_GIMP:
+      g_value_set_object (value, image->gimp);
+      break;
+    case PROP_ID:
+      g_value_set_int (value, private->ID);
+      break;
+    case PROP_WIDTH:
+      g_value_set_int (value, private->width);
+      break;
+    case PROP_HEIGHT:
+      g_value_set_int (value, private->height);
+      break;
+    case PROP_BASE_TYPE:
+      g_value_set_enum (value, private->base_type);
+      break;
+    case PROP_PRECISION:
+      g_value_set_enum (value, private->precision);
+      break;
+    case PROP_METADATA:
+      g_value_set_object (value, gimp_image_get_metadata (image));
+      break;
+    case PROP_BUFFER:
+      g_value_set_object (value, gimp_image_get_buffer (GIMP_PICKABLE (image)));
+      break;
+    case PROP_SYMMETRY:
+      g_value_set_gtype (value,
+                         private->active_symmetry ?
+                         G_TYPE_FROM_INSTANCE (private->active_symmetry) :
+                         G_TYPE_NONE);
+      break;
+    case PROP_CONVERTING:
+      g_value_set_boolean (value, private->converting);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_image_dispose (GObject *object)
+{
+  GimpImage        *image   = GIMP_IMAGE (object);
+  GimpImagePrivate *private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  if (private->colormap)
+    gimp_image_colormap_dispose (image);
+
+  gimp_image_undo_free (image);
+
+  g_signal_handlers_disconnect_by_func (private->layers->container,
+                                        gimp_image_invalidate,
+                                        image);
+
+  gimp_container_remove_handler (private->layers->container,
+                                 private->layer_offset_x_handler);
+  gimp_container_remove_handler (private->layers->container,
+                                 private->layer_offset_y_handler);
+  gimp_container_remove_handler (private->layers->container,
+                                 private->layer_bounding_box_handler);
+  gimp_container_remove_handler (private->layers->container,
+                                 private->layer_alpha_handler);
+
+  g_signal_handlers_disconnect_by_func (private->layers->container,
+                                        gimp_image_layers_changed,
+                                        image);
+
+  g_signal_handlers_disconnect_by_func (private->channels->container,
+                                        gimp_image_invalidate,
+                                        image);
+
+  gimp_container_remove_handler (private->channels->container,
+                                 private->channel_name_changed_handler);
+  gimp_container_remove_handler (private->channels->container,
+                                 private->channel_color_changed_handler);
+
+  g_signal_handlers_disconnect_by_func (private->channels->container,
+                                        gimp_image_channel_add,
+                                        image);
+  g_signal_handlers_disconnect_by_func (private->channels->container,
+                                        gimp_image_channel_remove,
+                                        image);
+
+  g_object_run_dispose (G_OBJECT (private->layers));
+  g_object_run_dispose (G_OBJECT (private->channels));
+  g_object_run_dispose (G_OBJECT (private->vectors));
+
+  G_OBJECT_CLASS (parent_class)->dispose (object);
+}
+
+static void
+gimp_image_finalize (GObject *object)
+{
+  GimpImage        *image   = GIMP_IMAGE (object);
+  GimpImagePrivate *private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  g_clear_object (&private->projection);
+  g_clear_object (&private->graph);
+  private->visible_mask = NULL;
+
+  if (private->colormap)
+    gimp_image_colormap_free (image);
+
+  if (private->color_profile)
+    _gimp_image_free_color_profile (image);
+
+  g_clear_object (&private->pickable_buffer);
+  g_clear_object (&private->metadata);
+  g_clear_object (&private->file);
+  g_clear_object (&private->imported_file);
+  g_clear_object (&private->exported_file);
+  g_clear_object (&private->save_a_copy_file);
+  g_clear_object (&private->untitled_file);
+  g_clear_object (&private->layers);
+  g_clear_object (&private->channels);
+  g_clear_object (&private->vectors);
+
+  if (private->layer_stack)
+    {
+      g_slist_free (private->layer_stack);
+      private->layer_stack = NULL;
+    }
+
+  g_clear_object (&private->selection_mask);
+  g_clear_object (&private->parasites);
+
+  if (private->guides)
+    {
+      g_list_free_full (private->guides, (GDestroyNotify) g_object_unref);
+      private->guides = NULL;
+    }
+
+  if (private->symmetries)
+    {
+      g_list_free_full (private->symmetries, g_object_unref);
+      private->symmetries = NULL;
+    }
+
+  g_clear_object (&private->grid);
+
+  if (private->sample_points)
+    {
+      g_list_free_full (private->sample_points,
+                        (GDestroyNotify) g_object_unref);
+      private->sample_points = NULL;
+    }
+
+  g_clear_object (&private->undo_stack);
+  g_clear_object (&private->redo_stack);
+
+  if (image->gimp && image->gimp->image_table)
+    {
+      gimp_id_table_remove (image->gimp->image_table, private->ID);
+      image->gimp = NULL;
+    }
+
+  g_clear_pointer (&private->display_name, g_free);
+  g_clear_pointer (&private->display_path, g_free);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gimp_image_name_changed (GimpObject *object)
+{
+  GimpImage        *image   = GIMP_IMAGE (object);
+  GimpImagePrivate *private = GIMP_IMAGE_GET_PRIVATE (image);
+  const gchar      *name;
+
+  if (GIMP_OBJECT_CLASS (parent_class)->name_changed)
+    GIMP_OBJECT_CLASS (parent_class)->name_changed (object);
+
+  g_clear_pointer (&private->display_name, g_free);
+  g_clear_pointer (&private->display_path, g_free);
+
+  /* We never want the empty string as a name, so change empty strings
+   * to NULL strings (without emitting the "name-changed" signal
+   * again)
+   */
+  name = gimp_object_get_name (object);
+  if (name && strlen (name) == 0)
+    {
+      gimp_object_name_free (object);
+      name = NULL;
+    }
+
+  g_clear_object (&private->file);
+
+  if (name)
+    private->file = g_file_new_for_uri (name);
+}
+
+static gint64
+gimp_image_get_memsize (GimpObject *object,
+                        gint64     *gui_size)
+{
+  GimpImage        *image   = GIMP_IMAGE (object);
+  GimpImagePrivate *private = GIMP_IMAGE_GET_PRIVATE (image);
+  gint64            memsize = 0;
+
+  if (gimp_image_get_colormap (image))
+    memsize += GIMP_IMAGE_COLORMAP_SIZE;
+
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (private->palette),
+                                      gui_size);
+
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (private->projection),
+                                      gui_size);
+
+  memsize += gimp_g_list_get_memsize (gimp_image_get_guides (image),
+                                      sizeof (GimpGuide));
+
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (private->grid), gui_size);
+
+  memsize += gimp_g_list_get_memsize (gimp_image_get_sample_points (image),
+                                      sizeof (GimpSamplePoint));
+
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (private->layers),
+                                      gui_size);
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (private->channels),
+                                      gui_size);
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (private->vectors),
+                                      gui_size);
+
+  memsize += gimp_g_slist_get_memsize (private->layer_stack, 0);
+
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (private->selection_mask),
+                                      gui_size);
+
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (private->parasites),
+                                      gui_size);
+
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (private->undo_stack),
+                                      gui_size);
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (private->redo_stack),
+                                      gui_size);
+
+  return memsize + GIMP_OBJECT_CLASS (parent_class)->get_memsize (object,
+                                                                  gui_size);
+}
+
+static gboolean
+gimp_image_get_size (GimpViewable *viewable,
+                     gint         *width,
+                     gint         *height)
+{
+  GimpImage *image = GIMP_IMAGE (viewable);
+
+  *width  = gimp_image_get_width  (image);
+  *height = gimp_image_get_height (image);
+
+  return TRUE;
+}
+
+static void
+gimp_image_size_changed (GimpViewable *viewable)
+{
+  GimpImage *image = GIMP_IMAGE (viewable);
+  GList     *all_items;
+  GList     *list;
+
+  if (GIMP_VIEWABLE_CLASS (parent_class)->size_changed)
+    GIMP_VIEWABLE_CLASS (parent_class)->size_changed (viewable);
+
+  all_items = gimp_image_get_layer_list (image);
+  for (list = all_items; list; list = g_list_next (list))
+    {
+      GimpLayerMask *mask = gimp_layer_get_mask (GIMP_LAYER (list->data));
+
+      gimp_viewable_size_changed (GIMP_VIEWABLE (list->data));
+
+      if (mask)
+        gimp_viewable_size_changed (GIMP_VIEWABLE (mask));
+    }
+  g_list_free (all_items);
+
+  all_items = gimp_image_get_channel_list (image);
+  g_list_free_full (all_items, (GDestroyNotify) gimp_viewable_size_changed);
+
+  all_items = gimp_image_get_vectors_list (image);
+  g_list_free_full (all_items, (GDestroyNotify) gimp_viewable_size_changed);
+
+  gimp_viewable_size_changed (GIMP_VIEWABLE (gimp_image_get_mask (image)));
+
+  gimp_image_metadata_update_pixel_size (image);
+
+  g_clear_object (&GIMP_IMAGE_GET_PRIVATE (image)->pickable_buffer);
+
+  gimp_image_update_bounding_box (image);
+}
+
+static gchar *
+gimp_image_get_description (GimpViewable  *viewable,
+                            gchar        **tooltip)
+{
+  GimpImage *image = GIMP_IMAGE (viewable);
+
+  if (tooltip)
+    *tooltip = g_strdup (gimp_image_get_display_path (image));
+
+  return g_strdup_printf ("%s-%d",
+                          gimp_image_get_display_name (image),
+                          gimp_image_get_ID (image));
+}
+
+static void
+gimp_image_real_mode_changed (GimpImage *image)
+{
+  gimp_projectable_structure_changed (GIMP_PROJECTABLE (image));
+}
+
+static void
+gimp_image_real_precision_changed (GimpImage *image)
+{
+  gimp_image_metadata_update_bits_per_sample (image);
+
+  gimp_projectable_structure_changed (GIMP_PROJECTABLE (image));
+}
+
+static void
+gimp_image_real_resolution_changed (GimpImage *image)
+{
+  gimp_image_metadata_update_resolution (image);
+}
+
+static void
+gimp_image_real_size_changed_detailed (GimpImage *image,
+                                       gint       previous_origin_x,
+                                       gint       previous_origin_y,
+                                       gint       previous_width,
+                                       gint       previous_height)
+{
+  /* Whenever GimpImage::size-changed-detailed is emitted, so is
+   * GimpViewable::size-changed. Clients choose what signal to listen
+   * to depending on how much info they need.
+   */
+  gimp_viewable_size_changed (GIMP_VIEWABLE (image));
+}
+
+static void
+gimp_image_real_unit_changed (GimpImage *image)
+{
+  gimp_image_metadata_update_resolution (image);
+}
+
+static void
+gimp_image_real_colormap_changed (GimpImage *image,
+                                  gint       color_index)
+{
+  GimpImagePrivate *private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  if (private->colormap && private->n_colors > 0)
+    {
+      babl_palette_set_palette (private->babl_palette_rgb,
+                                gimp_babl_format (GIMP_RGB,
+                                                  private->precision, FALSE),
+                                private->colormap,
+                                private->n_colors);
+      babl_palette_set_palette (private->babl_palette_rgba,
+                                gimp_babl_format (GIMP_RGB,
+                                                  private->precision, FALSE),
+                                private->colormap,
+                                private->n_colors);
+    }
+
+  if (gimp_image_get_base_type (image) == GIMP_INDEXED)
+    {
+      /* A colormap alteration affects the whole image */
+      gimp_image_invalidate_all (image);
+
+      gimp_item_stack_invalidate_previews (GIMP_ITEM_STACK (private->layers->container));
+    }
+}
+
+static const guint8 *
+gimp_image_color_managed_get_icc_profile (GimpColorManaged *managed,
+                                          gsize            *len)
+{
+  return gimp_image_get_icc_profile (GIMP_IMAGE (managed), len);
+}
+
+static GimpColorProfile *
+gimp_image_color_managed_get_color_profile (GimpColorManaged *managed)
+{
+  GimpImage        *image   = GIMP_IMAGE (managed);
+  GimpColorProfile *profile = NULL;
+
+  if (gimp_image_get_is_color_managed (image))
+    profile = gimp_image_get_color_profile (image);
+
+  if (! profile)
+    profile = gimp_image_get_builtin_color_profile (image);
+
+  return profile;
+}
+
+static void
+gimp_image_color_managed_profile_changed (GimpColorManaged *managed)
+{
+  GimpImage     *image  = GIMP_IMAGE (managed);
+  GimpItemStack *layers = GIMP_ITEM_STACK (gimp_image_get_layers (image));
+
+  gimp_image_metadata_update_colorspace (image);
+
+  gimp_projectable_structure_changed (GIMP_PROJECTABLE (image));
+  gimp_viewable_invalidate_preview (GIMP_VIEWABLE (image));
+  gimp_item_stack_profile_changed (layers);
+}
+
+static void
+gimp_image_projectable_flush (GimpProjectable *projectable,
+                              gboolean         invalidate_preview)
+{
+  GimpImage        *image   = GIMP_IMAGE (projectable);
+  GimpImagePrivate *private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  if (private->flush_accum.alpha_changed)
+    {
+      gimp_image_alpha_changed (image);
+      private->flush_accum.alpha_changed = FALSE;
+    }
+
+  if (private->flush_accum.mask_changed)
+    {
+      gimp_image_mask_changed (image);
+      private->flush_accum.mask_changed = FALSE;
+    }
+
+  if (private->flush_accum.floating_selection_changed)
+    {
+      gimp_image_floating_selection_changed (image);
+      private->flush_accum.floating_selection_changed = FALSE;
+    }
+
+  if (private->flush_accum.preview_invalidated)
+    {
+      /*  don't invalidate the preview here, the projection does this when
+       *  it is completely constructed.
+       */
+      private->flush_accum.preview_invalidated = FALSE;
+    }
+}
+
+static GimpImage *
+gimp_image_get_image (GimpProjectable *projectable)
+{
+  return GIMP_IMAGE (projectable);
+}
+
+static const Babl *
+gimp_image_get_proj_format (GimpProjectable *projectable)
+{
+  GimpImage        *image   = GIMP_IMAGE (projectable);
+  GimpImagePrivate *private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  switch (private->base_type)
+    {
+    case GIMP_RGB:
+    case GIMP_INDEXED:
+      return gimp_image_get_format (image, GIMP_RGB,
+                                    gimp_image_get_precision (image), TRUE);
+
+    case GIMP_GRAY:
+      return gimp_image_get_format (image, GIMP_GRAY,
+                                    gimp_image_get_precision (image), TRUE);
+    }
+
+  g_return_val_if_reached (NULL);
+}
+
+static void
+gimp_image_pickable_flush (GimpPickable *pickable)
+{
+  GimpImagePrivate *private = GIMP_IMAGE_GET_PRIVATE (pickable);
+
+  return gimp_pickable_flush (GIMP_PICKABLE (private->projection));
+}
+
+static GeglBuffer *
+gimp_image_get_buffer (GimpPickable *pickable)
+{
+  GimpImage        *image   = GIMP_IMAGE (pickable);
+  GimpImagePrivate *private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  if (! private->pickable_buffer)
+    {
+      GeglBuffer *buffer;
+
+      buffer = gimp_pickable_get_buffer (GIMP_PICKABLE (private->projection));
+
+      if (! private->show_all)
+        {
+          private->pickable_buffer = g_object_ref (buffer);
+        }
+      else
+        {
+          private->pickable_buffer = gegl_buffer_create_sub_buffer (
+            buffer,
+            GEGL_RECTANGLE (0, 0,
+                            gimp_image_get_width  (image),
+                            gimp_image_get_height (image)));
+        }
+    }
+
+  return private->pickable_buffer;
+}
+
+static gboolean
+gimp_image_get_pixel_at (GimpPickable *pickable,
+                         gint          x,
+                         gint          y,
+                         const Babl   *format,
+                         gpointer      pixel)
+{
+  GimpImage        *image   = GIMP_IMAGE (pickable);
+  GimpImagePrivate *private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  if (x >= 0                            &&
+      y >= 0                            &&
+      x < gimp_image_get_width  (image) &&
+      y < gimp_image_get_height (image))
+    {
+      return gimp_pickable_get_pixel_at (GIMP_PICKABLE (private->projection),
+                                         x, y, format, pixel);
+    }
+
+  return FALSE;
+}
+
+static gdouble
+gimp_image_get_opacity_at (GimpPickable *pickable,
+                           gint          x,
+                           gint          y)
+{
+  GimpImage        *image   = GIMP_IMAGE (pickable);
+  GimpImagePrivate *private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  if (x >= 0                            &&
+      y >= 0                            &&
+      x < gimp_image_get_width  (image) &&
+      y < gimp_image_get_height (image))
+    {
+      return gimp_pickable_get_opacity_at (GIMP_PICKABLE (private->projection),
+                                           x, y);
+    }
+
+  return FALSE;
+}
+
+static void
+gimp_image_get_pixel_average (GimpPickable        *pickable,
+                              const GeglRectangle *rect,
+                              const Babl          *format,
+                              gpointer             pixel)
+{
+  GeglBuffer *buffer = gimp_pickable_get_buffer (pickable);
+
+  return gimp_gegl_average_color (buffer, rect, TRUE, GEGL_ABYSS_NONE, format,
+                                  pixel);
+}
+
+static void
+gimp_image_pixel_to_srgb (GimpPickable *pickable,
+                          const Babl   *format,
+                          gpointer      pixel,
+                          GimpRGB      *color)
+{
+  gimp_image_color_profile_pixel_to_srgb (GIMP_IMAGE (pickable),
+                                          format, pixel, color);
+}
+
+static void
+gimp_image_srgb_to_pixel (GimpPickable  *pickable,
+                          const GimpRGB *color,
+                          const Babl    *format,
+                          gpointer       pixel)
+{
+  gimp_image_color_profile_srgb_to_pixel (GIMP_IMAGE (pickable),
+                                          color, format, pixel);
+}
+
+static GeglRectangle
+gimp_image_get_bounding_box (GimpProjectable *projectable)
+{
+  GimpImage *image = GIMP_IMAGE (projectable);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->bounding_box;
+}
+
+static GeglNode *
+gimp_image_get_graph (GimpProjectable *projectable)
+{
+  GimpImage         *image   = GIMP_IMAGE (projectable);
+  GimpImagePrivate  *private = GIMP_IMAGE_GET_PRIVATE (image);
+  GeglNode          *layers_node;
+  GeglNode          *channels_node;
+  GeglNode          *output;
+  GimpComponentMask  mask;
+
+  if (private->graph)
+    return private->graph;
+
+  private->graph = gegl_node_new ();
+
+  layers_node =
+    gimp_filter_stack_get_graph (GIMP_FILTER_STACK (private->layers->container));
+
+  gegl_node_add_child (private->graph, layers_node);
+
+  mask = ~gimp_image_get_visible_mask (image) & GIMP_COMPONENT_MASK_ALL;
+
+  private->visible_mask =
+    gegl_node_new_child (private->graph,
+                         "operation", "gimp:mask-components",
+                         "mask",      mask,
+                         "alpha",     1.0,
+                         NULL);
+
+  gegl_node_connect_to (layers_node,           "output",
+                        private->visible_mask, "input");
+
+  channels_node =
+    gimp_filter_stack_get_graph (GIMP_FILTER_STACK (private->channels->container));
+
+  gegl_node_add_child (private->graph, channels_node);
+
+  gegl_node_connect_to (private->visible_mask, "output",
+                        channels_node,         "input");
+
+  output = gegl_node_get_output_proxy (private->graph, "output");
+
+  gegl_node_connect_to (channels_node, "output",
+                        output,        "input");
+
+  return private->graph;
+}
+
+static void
+gimp_image_projection_buffer_notify (GimpProjection   *projection,
+                                     const GParamSpec *pspec,
+                                     GimpImage        *image)
+{
+  g_clear_object (&GIMP_IMAGE_GET_PRIVATE (image)->pickable_buffer);
+}
+
+static void
+gimp_image_mask_update (GimpDrawable *drawable,
+                        gint          x,
+                        gint          y,
+                        gint          width,
+                        gint          height,
+                        GimpImage    *image)
+{
+  GIMP_IMAGE_GET_PRIVATE (image)->flush_accum.mask_changed = TRUE;
+}
+
+static void
+gimp_image_layers_changed (GimpContainer *container,
+                           GimpChannel   *channel,
+                           GimpImage     *image)
+{
+  gimp_image_update_bounding_box (image);
+}
+
+static void
+gimp_image_layer_offset_changed (GimpDrawable     *drawable,
+                                 const GParamSpec *pspec,
+                                 GimpImage        *image)
+{
+  gimp_image_update_bounding_box (image);
+}
+
+static void
+gimp_image_layer_bounding_box_changed (GimpDrawable *drawable,
+                                       GimpImage    *image)
+{
+  gimp_image_update_bounding_box (image);
+}
+
+static void
+gimp_image_layer_alpha_changed (GimpDrawable *drawable,
+                                GimpImage    *image)
+{
+  GimpImagePrivate *private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  if (gimp_container_get_n_children (private->layers->container) == 1)
+    private->flush_accum.alpha_changed = TRUE;
+}
+
+static void
+gimp_image_channel_add (GimpContainer *container,
+                        GimpChannel   *channel,
+                        GimpImage     *image)
+{
+  if (! strcmp (GIMP_IMAGE_QUICK_MASK_NAME,
+                gimp_object_get_name (channel)))
+    {
+      gimp_image_set_quick_mask_state (image, TRUE);
+    }
+}
+
+static void
+gimp_image_channel_remove (GimpContainer *container,
+                           GimpChannel   *channel,
+                           GimpImage     *image)
+{
+  if (! strcmp (GIMP_IMAGE_QUICK_MASK_NAME,
+                gimp_object_get_name (channel)))
+    {
+      gimp_image_set_quick_mask_state (image, FALSE);
+    }
+}
+
+static void
+gimp_image_channel_name_changed (GimpChannel *channel,
+                                 GimpImage   *image)
+{
+  if (! strcmp (GIMP_IMAGE_QUICK_MASK_NAME,
+                gimp_object_get_name (channel)))
+    {
+      gimp_image_set_quick_mask_state (image, TRUE);
+    }
+  else if (gimp_image_get_quick_mask_state (image) &&
+           ! gimp_image_get_quick_mask (image))
+    {
+      gimp_image_set_quick_mask_state (image, FALSE);
+    }
+}
+
+static void
+gimp_image_channel_color_changed (GimpChannel *channel,
+                                  GimpImage   *image)
+{
+  if (! strcmp (GIMP_IMAGE_QUICK_MASK_NAME,
+                gimp_object_get_name (channel)))
+    {
+      GIMP_IMAGE_GET_PRIVATE (image)->quick_mask_color = channel->color;
+    }
+}
+
+static void
+gimp_image_active_layer_notify (GimpItemTree     *tree,
+                                const GParamSpec *pspec,
+                                GimpImage        *image)
+{
+  GimpImagePrivate *private = GIMP_IMAGE_GET_PRIVATE (image);
+  GimpLayer        *layer   = gimp_image_get_active_layer (image);
+
+  if (layer)
+    {
+      /*  Configure the layer stack to reflect this change  */
+      private->layer_stack = g_slist_remove (private->layer_stack, layer);
+      private->layer_stack = g_slist_prepend (private->layer_stack, layer);
+    }
+
+  g_signal_emit (image, gimp_image_signals[ACTIVE_LAYER_CHANGED], 0);
+
+  if (layer && gimp_image_get_active_channel (image))
+    gimp_image_set_active_channel (image, NULL);
+}
+
+static void
+gimp_image_active_channel_notify (GimpItemTree     *tree,
+                                  const GParamSpec *pspec,
+                                  GimpImage        *image)
+{
+  GimpChannel *channel = gimp_image_get_active_channel (image);
+
+  g_signal_emit (image, gimp_image_signals[ACTIVE_CHANNEL_CHANGED], 0);
+
+  if (channel && gimp_image_get_active_layer (image))
+    gimp_image_set_active_layer (image, NULL);
+}
+
+static void
+gimp_image_active_vectors_notify (GimpItemTree     *tree,
+                                  const GParamSpec *pspec,
+                                  GimpImage        *image)
+{
+  g_signal_emit (image, gimp_image_signals[ACTIVE_VECTORS_CHANGED], 0);
+}
+
+static void
+gimp_image_freeze_bounding_box (GimpImage *image)
+{
+  GimpImagePrivate *private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  private->bounding_box_freeze_count++;
+}
+
+static void
+gimp_image_thaw_bounding_box (GimpImage *image)
+{
+  GimpImagePrivate *private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  private->bounding_box_freeze_count--;
+
+  if (private->bounding_box_freeze_count == 0 &&
+      private->bounding_box_update_pending)
+    {
+      private->bounding_box_update_pending = FALSE;
+
+      gimp_image_update_bounding_box (image);
+    }
+}
+
+static void
+gimp_image_update_bounding_box (GimpImage *image)
+{
+  GimpImagePrivate *private = GIMP_IMAGE_GET_PRIVATE (image);
+  GeglRectangle     bounding_box;
+
+  if (private->bounding_box_freeze_count > 0)
+    {
+      private->bounding_box_update_pending = TRUE;
+
+      return;
+    }
+
+  bounding_box.x      = 0;
+  bounding_box.y      = 0;
+  bounding_box.width  = gimp_image_get_width  (image);
+  bounding_box.height = gimp_image_get_height (image);
+
+  if (private->show_all)
+    {
+      GList *iter;
+
+      for (iter = gimp_image_get_layer_iter (image);
+           iter;
+           iter = g_list_next (iter))
+        {
+          GimpLayer     *layer = iter->data;
+          GeglRectangle  layer_bounding_box;
+          gint           offset_x;
+          gint           offset_y;
+
+          gimp_item_get_offset (GIMP_ITEM (layer), &offset_x, &offset_y);
+
+          layer_bounding_box = gimp_drawable_get_bounding_box (
+            GIMP_DRAWABLE (layer));
+
+          layer_bounding_box.x += offset_x;
+          layer_bounding_box.y += offset_y;
+
+          gegl_rectangle_bounding_box (&bounding_box,
+                                       &bounding_box, &layer_bounding_box);
+        }
+    }
+
+  if (! gegl_rectangle_equal (&bounding_box, &private->bounding_box))
+    {
+      private->bounding_box = bounding_box;
+
+      gimp_projectable_bounds_changed (GIMP_PROJECTABLE (image), 0, 0);
+    }
+}
+
+
+/*  public functions  */
+
+GimpImage *
+gimp_image_new (Gimp              *gimp,
+                gint               width,
+                gint               height,
+                GimpImageBaseType  base_type,
+                GimpPrecision      precision)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+  g_return_val_if_fail (gimp_babl_is_valid (base_type, precision), NULL);
+
+  return g_object_new (GIMP_TYPE_IMAGE,
+                       "gimp",      gimp,
+                       "width",     width,
+                       "height",    height,
+                       "base-type", base_type,
+                       "precision", precision,
+                       NULL);
+}
+
+gint64
+gimp_image_estimate_memsize (GimpImage         *image,
+                             GimpComponentType  component_type,
+                             gint               width,
+                             gint               height)
+{
+  GList  *drawables;
+  GList  *list;
+  gint    current_width;
+  gint    current_height;
+  gint64  current_size;
+  gint64  scalable_size = 0;
+  gint64  scaled_size   = 0;
+  gint64  new_size;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), 0);
+
+  current_width  = gimp_image_get_width (image);
+  current_height = gimp_image_get_height (image);
+  current_size   = gimp_object_get_memsize (GIMP_OBJECT (image), NULL);
+
+  /*  the part of the image's memsize that scales linearly with the image  */
+  drawables = gimp_image_item_list_get_list (image,
+                                             GIMP_ITEM_TYPE_LAYERS |
+                                             GIMP_ITEM_TYPE_CHANNELS,
+                                             GIMP_ITEM_SET_ALL);
+
+  gimp_image_item_list_filter (drawables);
+
+  drawables = g_list_prepend (drawables, gimp_image_get_mask (image));
+
+  for (list = drawables; list; list = g_list_next (list))
+    {
+      GimpDrawable *drawable = list->data;
+      gdouble       drawable_width;
+      gdouble       drawable_height;
+
+      drawable_width  = gimp_item_get_width  (GIMP_ITEM (drawable));
+      drawable_height = gimp_item_get_height (GIMP_ITEM (drawable));
+
+      scalable_size += gimp_drawable_estimate_memsize (drawable,
+                                                       gimp_drawable_get_component_type (drawable),
+                                                       drawable_width,
+                                                       drawable_height);
+
+      scaled_size += gimp_drawable_estimate_memsize (drawable,
+                                                     component_type,
+                                                     drawable_width * width /
+                                                     current_width,
+                                                     drawable_height * height /
+                                                     current_height);
+    }
+
+  g_list_free (drawables);
+
+  scalable_size +=
+    gimp_projection_estimate_memsize (gimp_image_get_base_type (image),
+                                      gimp_image_get_component_type (image),
+                                      gimp_image_get_width (image),
+                                      gimp_image_get_height (image));
+
+  scaled_size +=
+    gimp_projection_estimate_memsize (gimp_image_get_base_type (image),
+                                      component_type,
+                                      width, height);
+
+  GIMP_LOG (IMAGE_SCALE,
+            "scalable_size = %"G_GINT64_FORMAT"  scaled_size = %"G_GINT64_FORMAT,
+            scalable_size, scaled_size);
+
+  new_size = current_size - scalable_size + scaled_size;
+
+  return new_size;
+}
+
+GimpImageBaseType
+gimp_image_get_base_type (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), -1);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->base_type;
+}
+
+GimpComponentType
+gimp_image_get_component_type (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), -1);
+
+  return gimp_babl_component_type (GIMP_IMAGE_GET_PRIVATE (image)->precision);
+}
+
+GimpPrecision
+gimp_image_get_precision (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), -1);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->precision;
+}
+
+const Babl *
+gimp_image_get_format (GimpImage         *image,
+                       GimpImageBaseType  base_type,
+                       GimpPrecision      precision,
+                       gboolean           with_alpha)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  switch (base_type)
+    {
+    case GIMP_RGB:
+    case GIMP_GRAY:
+      return gimp_babl_format (base_type, precision, with_alpha);
+
+    case GIMP_INDEXED:
+      if (precision == GIMP_PRECISION_U8_GAMMA)
+        {
+          if (with_alpha)
+            return gimp_image_colormap_get_rgba_format (image);
+          else
+            return gimp_image_colormap_get_rgb_format (image);
+        }
+    }
+
+  g_return_val_if_reached (NULL);
+}
+
+const Babl *
+gimp_image_get_layer_format (GimpImage *image,
+                             gboolean   with_alpha)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  return gimp_image_get_format (image,
+                                gimp_image_get_base_type (image),
+                                gimp_image_get_precision (image),
+                                with_alpha);
+}
+
+const Babl *
+gimp_image_get_channel_format (GimpImage *image)
+{
+  GimpPrecision precision;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  precision = gimp_image_get_precision (image);
+
+  if (precision == GIMP_PRECISION_U8_GAMMA)
+    return gimp_image_get_format (image, GIMP_GRAY,
+                                  gimp_image_get_precision (image),
+                                  FALSE);
+
+  return gimp_babl_mask_format (precision);
+}
+
+const Babl *
+gimp_image_get_mask_format (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  return gimp_babl_mask_format (gimp_image_get_precision (image));
+}
+
+GimpLayerMode
+gimp_image_get_default_new_layer_mode (GimpImage *image)
+{
+  GimpImagePrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), GIMP_LAYER_MODE_NORMAL);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  if (private->new_layer_mode == -1)
+    {
+      GList *layers = gimp_image_get_layer_list (image);
+
+      if (layers)
+        {
+          GList *list;
+
+          for (list = layers; list; list = g_list_next (list))
+            {
+              GimpLayer     *layer = list->data;
+              GimpLayerMode  mode  = gimp_layer_get_mode (layer);
+
+              if (! gimp_layer_mode_is_legacy (mode))
+                {
+                  /*  any non-legacy layer switches the mode to non-legacy
+                   */
+                  private->new_layer_mode = GIMP_LAYER_MODE_NORMAL;
+                  break;
+                }
+            }
+
+          /*  only if all layers are legacy, the mode is also legacy
+           */
+          if (! list)
+            private->new_layer_mode = GIMP_LAYER_MODE_NORMAL_LEGACY;
+
+          g_list_free (layers);
+        }
+      else
+        {
+          /*  empty images are never considered legacy
+           */
+          private->new_layer_mode = GIMP_LAYER_MODE_NORMAL;
+        }
+    }
+
+  return private->new_layer_mode;
+}
+
+void
+gimp_image_unset_default_new_layer_mode (GimpImage *image)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  GIMP_IMAGE_GET_PRIVATE (image)->new_layer_mode = -1;
+}
+
+gint
+gimp_image_get_ID (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), -1);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->ID;
+}
+
+GimpImage *
+gimp_image_get_by_ID (Gimp *gimp,
+                      gint  image_id)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  if (gimp->image_table == NULL)
+    return NULL;
+
+  return (GimpImage *) gimp_id_table_lookup (gimp->image_table, image_id);
+}
+
+void
+gimp_image_set_file (GimpImage *image,
+                     GFile     *file)
+{
+  GimpImagePrivate *private;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (file == NULL || G_IS_FILE (file));
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  if (private->file != file)
+    {
+      gimp_object_take_name (GIMP_OBJECT (image),
+                             file ? g_file_get_uri (file) : NULL);
+    }
+}
+
+/**
+ * gimp_image_get_untitled_file:
+ *
+ * Returns: A #GFile saying "Untitled" for newly created images.
+ **/
+GFile *
+gimp_image_get_untitled_file (GimpImage *image)
+{
+  GimpImagePrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  if (! private->untitled_file)
+    private->untitled_file = g_file_new_for_uri (_("Untitled"));
+
+  return private->untitled_file;
+}
+
+/**
+ * gimp_image_get_file_or_untitled:
+ * @image: A #GimpImage.
+ *
+ * Get the file of the XCF image, or the "Untitled" file if there is no file.
+ *
+ * Returns: A #GFile.
+ **/
+GFile *
+gimp_image_get_file_or_untitled (GimpImage *image)
+{
+  GFile *file;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  file = gimp_image_get_file (image);
+
+  if (! file)
+    file = gimp_image_get_untitled_file (image);
+
+  return file;
+}
+
+/**
+ * gimp_image_get_file:
+ * @image: A #GimpImage.
+ *
+ * Get the file of the XCF image, or NULL if there is no file.
+ *
+ * Returns: The file, or NULL.
+ **/
+GFile *
+gimp_image_get_file (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->file;
+}
+
+/**
+ * gimp_image_get_imported_file:
+ * @image: A #GimpImage.
+ *
+ * Returns: The file of the imported image, or NULL if the image has
+ * been saved as XCF after it was imported.
+ **/
+GFile *
+gimp_image_get_imported_file (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->imported_file;
+}
+
+/**
+ * gimp_image_get_exported_file:
+ * @image: A #GimpImage.
+ *
+ * Returns: The file of the image last exported from this XCF file, or
+ * NULL if the image has never been exported.
+ **/
+GFile *
+gimp_image_get_exported_file (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->exported_file;
+}
+
+/**
+ * gimp_image_get_save_a_copy_file:
+ * @image: A #GimpImage.
+ *
+ * Returns: The URI of the last copy that was saved of this XCF file.
+ **/
+GFile *
+gimp_image_get_save_a_copy_file (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->save_a_copy_file;
+}
+
+/**
+ * gimp_image_get_any_file:
+ * @image: A #GimpImage.
+ *
+ * Returns: The XCF file, the imported file, or the exported file, in
+ * that order of precedence.
+ **/
+GFile *
+gimp_image_get_any_file (GimpImage *image)
+{
+  GFile *file;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  file = gimp_image_get_file (image);
+  if (! file)
+    {
+      file = gimp_image_get_imported_file (image);
+      if (! file)
+        {
+          file = gimp_image_get_exported_file (image);
+        }
+    }
+
+  return file;
+}
+
+/**
+ * gimp_image_set_imported_uri:
+ * @image: A #GimpImage.
+ * @file:
+ *
+ * Sets the URI this file was imported from.
+ **/
+void
+gimp_image_set_imported_file (GimpImage *image,
+                              GFile     *file)
+{
+  GimpImagePrivate *private;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (file == NULL || G_IS_FILE (file));
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  if (g_set_object (&private->imported_file, file))
+    {
+      gimp_object_name_changed (GIMP_OBJECT (image));
+    }
+
+  if (! private->resolution_set && file != NULL)
+    {
+      /* Unlike new files (which follow technological progress and will
+       * use higher default resolution, or explicitly chosen templates),
+       * imported files have a more backward-compatible value.
+       *
+       * 72 PPI is traditionnally the default value when none other had
+       * been explicitly set (for instance it is the default when no
+       * resolution metadata was set in Exif version 2.32, and below,
+       * standard). This historical value will only ever apply to loaded
+       * images. New images will continue having more modern or
+       * templated defaults.
+       */
+      private->xresolution     = 72.0;
+      private->yresolution     = 72.0;
+      private->resolution_unit = GIMP_UNIT_INCH;
+    }
+}
+
+/**
+ * gimp_image_set_exported_file:
+ * @image: A #GimpImage.
+ * @file:
+ *
+ * Sets the file this image was last exported to. Note that saving as
+ * XCF is not "exporting".
+ **/
+void
+gimp_image_set_exported_file (GimpImage *image,
+                              GFile     *file)
+{
+  GimpImagePrivate *private;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (file == NULL || G_IS_FILE (file));
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  if (g_set_object (&private->exported_file, file))
+    {
+      gimp_object_name_changed (GIMP_OBJECT (image));
+    }
+}
+
+/**
+ * gimp_image_set_save_a_copy_file:
+ * @image: A #GimpImage.
+ * @uri:
+ *
+ * Set the URI to the last copy this XCF file was saved to through the
+ * "save a copy" action.
+ **/
+void
+gimp_image_set_save_a_copy_file (GimpImage *image,
+                                 GFile     *file)
+{
+  GimpImagePrivate *private;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (file == NULL || G_IS_FILE (file));
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  g_set_object (&private->save_a_copy_file, file);
+}
+
+static gchar *
+gimp_image_format_display_uri (GimpImage *image,
+                               gboolean   basename)
+{
+  const gchar *uri_format    = NULL;
+  const gchar *export_status = NULL;
+  GFile       *file          = NULL;
+  GFile       *source        = NULL;
+  GFile       *dest          = NULL;
+  GFile       *display_file  = NULL;
+  gboolean     is_imported;
+  gboolean     is_exported;
+  gchar       *display_uri   = NULL;
+  gchar       *format_string;
+  gchar       *tmp;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  file   = gimp_image_get_file (image);
+  source = gimp_image_get_imported_file (image);
+  dest   = gimp_image_get_exported_file (image);
+
+  is_imported = (source != NULL);
+  is_exported = (dest   != NULL);
+
+  if (file)
+    {
+      display_file = g_object_ref (file);
+      uri_format   = "%s";
+    }
+  else
+    {
+      if (is_imported)
+        display_file = source;
+
+      /* Calculate filename suffix */
+      if (! gimp_image_is_export_dirty (image))
+        {
+          if (is_exported)
+            {
+              display_file  = dest;
+              export_status = _(" (exported)");
+            }
+          else if (is_imported)
+            {
+              export_status = _(" (overwritten)");
+            }
+          else
+            {
+              g_warning ("Unexpected code path, Save+export implementation is buggy!");
+            }
+        }
+      else if (is_imported)
+        {
+          export_status = _(" (imported)");
+        }
+
+      if (display_file)
+        display_file = gimp_file_with_new_extension (display_file, NULL);
+
+      uri_format = "[%s]";
+    }
+
+  if (! display_file)
+    display_file = g_object_ref (gimp_image_get_untitled_file (image));
+
+  if (basename)
+    display_uri = g_path_get_basename (gimp_file_get_utf8_name (display_file));
+  else
+    display_uri = g_strdup (gimp_file_get_utf8_name (display_file));
+
+  g_object_unref (display_file);
+
+  format_string = g_strconcat (uri_format, export_status, NULL);
+
+  tmp = g_strdup_printf (format_string, display_uri);
+  g_free (display_uri);
+  display_uri = tmp;
+
+  g_free (format_string);
+
+  return display_uri;
+}
+
+const gchar *
+gimp_image_get_display_name (GimpImage *image)
+{
+  GimpImagePrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  if (! private->display_name)
+    private->display_name = gimp_image_format_display_uri (image, TRUE);
+
+  return private->display_name;
+}
+
+const gchar *
+gimp_image_get_display_path (GimpImage *image)
+{
+  GimpImagePrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  if (! private->display_path)
+    private->display_path = gimp_image_format_display_uri (image, FALSE);
+
+  return private->display_path;
+}
+
+void
+gimp_image_set_load_proc (GimpImage           *image,
+                          GimpPlugInProcedure *proc)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  GIMP_IMAGE_GET_PRIVATE (image)->load_proc = proc;
+}
+
+GimpPlugInProcedure *
+gimp_image_get_load_proc (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->load_proc;
+}
+
+void
+gimp_image_set_save_proc (GimpImage           *image,
+                          GimpPlugInProcedure *proc)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  GIMP_IMAGE_GET_PRIVATE (image)->save_proc = proc;
+}
+
+GimpPlugInProcedure *
+gimp_image_get_save_proc (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->save_proc;
+}
+
+void
+gimp_image_set_export_proc (GimpImage           *image,
+                            GimpPlugInProcedure *proc)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  GIMP_IMAGE_GET_PRIVATE (image)->export_proc = proc;
+}
+
+GimpPlugInProcedure *
+gimp_image_get_export_proc (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->export_proc;
+}
+
+gint
+gimp_image_get_xcf_version (GimpImage    *image,
+                            gboolean      zlib_compression,
+                            gint         *gimp_version,
+                            const gchar **version_string,
+                            gchar       **version_reason)
+{
+  GList       *layers;
+  GList       *list;
+  GList       *reasons = NULL;
+  gint         version = 0;  /* default to oldest */
+  const gchar *enum_desc;
+
+#define ADD_REASON(_reason)                                       \
+  if (version_reason) {                                           \
+    gchar *tmp = _reason;                                         \
+    if (g_list_find_custom (reasons, tmp, (GCompareFunc) strcmp)) \
+      g_free (tmp);                                               \
+    else                                                          \
+      reasons = g_list_prepend (reasons, tmp); }
+
+  /* need version 1 for colormaps */
+  if (gimp_image_get_colormap (image))
+    version = 1;
+
+  layers = gimp_image_get_layer_list (image);
+
+  for (list = layers; list; list = g_list_next (list))
+    {
+      GimpLayer *layer = GIMP_LAYER (list->data);
+
+      switch (gimp_layer_get_mode (layer))
+        {
+          /*  Modes that exist since ancient times  */
+        case GIMP_LAYER_MODE_NORMAL_LEGACY:
+        case GIMP_LAYER_MODE_DISSOLVE:
+        case GIMP_LAYER_MODE_BEHIND_LEGACY:
+        case GIMP_LAYER_MODE_MULTIPLY_LEGACY:
+        case GIMP_LAYER_MODE_SCREEN_LEGACY:
+        case GIMP_LAYER_MODE_OVERLAY_LEGACY:
+        case GIMP_LAYER_MODE_DIFFERENCE_LEGACY:
+        case GIMP_LAYER_MODE_ADDITION_LEGACY:
+        case GIMP_LAYER_MODE_SUBTRACT_LEGACY:
+        case GIMP_LAYER_MODE_DARKEN_ONLY_LEGACY:
+        case GIMP_LAYER_MODE_LIGHTEN_ONLY_LEGACY:
+        case GIMP_LAYER_MODE_HSV_HUE_LEGACY:
+        case GIMP_LAYER_MODE_HSV_SATURATION_LEGACY:
+        case GIMP_LAYER_MODE_HSL_COLOR_LEGACY:
+        case GIMP_LAYER_MODE_HSV_VALUE_LEGACY:
+        case GIMP_LAYER_MODE_DIVIDE_LEGACY:
+        case GIMP_LAYER_MODE_DODGE_LEGACY:
+        case GIMP_LAYER_MODE_BURN_LEGACY:
+        case GIMP_LAYER_MODE_HARDLIGHT_LEGACY:
+          break;
+
+          /*  Since 2.6  */
+        case GIMP_LAYER_MODE_SOFTLIGHT_LEGACY:
+        case GIMP_LAYER_MODE_GRAIN_EXTRACT_LEGACY:
+        case GIMP_LAYER_MODE_GRAIN_MERGE_LEGACY:
+        case GIMP_LAYER_MODE_COLOR_ERASE_LEGACY:
+          gimp_enum_get_value (GIMP_TYPE_LAYER_MODE,
+                               gimp_layer_get_mode (layer),
+                               NULL, NULL, &enum_desc, NULL);
+          ADD_REASON (g_strdup_printf (_("Layer mode '%s' was added in %s"),
+                                       enum_desc, "GIMP 2.6"));
+          version = MAX (2, version);
+          break;
+
+          /*  Since 2.10  */
+        case GIMP_LAYER_MODE_OVERLAY:
+        case GIMP_LAYER_MODE_LCH_HUE:
+        case GIMP_LAYER_MODE_LCH_CHROMA:
+        case GIMP_LAYER_MODE_LCH_COLOR:
+        case GIMP_LAYER_MODE_LCH_LIGHTNESS:
+          gimp_enum_get_value (GIMP_TYPE_LAYER_MODE,
+                               gimp_layer_get_mode (layer),
+                               NULL, NULL, &enum_desc, NULL);
+          ADD_REASON (g_strdup_printf (_("Layer mode '%s' was added in %s"),
+                                       enum_desc, "GIMP 2.10"));
+          version = MAX (9, version);
+          break;
+
+          /*  Since 2.10  */
+        case GIMP_LAYER_MODE_NORMAL:
+        case GIMP_LAYER_MODE_BEHIND:
+        case GIMP_LAYER_MODE_MULTIPLY:
+        case GIMP_LAYER_MODE_SCREEN:
+        case GIMP_LAYER_MODE_DIFFERENCE:
+        case GIMP_LAYER_MODE_ADDITION:
+        case GIMP_LAYER_MODE_SUBTRACT:
+        case GIMP_LAYER_MODE_DARKEN_ONLY:
+        case GIMP_LAYER_MODE_LIGHTEN_ONLY:
+        case GIMP_LAYER_MODE_HSV_HUE:
+        case GIMP_LAYER_MODE_HSV_SATURATION:
+        case GIMP_LAYER_MODE_HSL_COLOR:
+        case GIMP_LAYER_MODE_HSV_VALUE:
+        case GIMP_LAYER_MODE_DIVIDE:
+        case GIMP_LAYER_MODE_DODGE:
+        case GIMP_LAYER_MODE_BURN:
+        case GIMP_LAYER_MODE_HARDLIGHT:
+        case GIMP_LAYER_MODE_SOFTLIGHT:
+        case GIMP_LAYER_MODE_GRAIN_EXTRACT:
+        case GIMP_LAYER_MODE_GRAIN_MERGE:
+        case GIMP_LAYER_MODE_VIVID_LIGHT:
+        case GIMP_LAYER_MODE_PIN_LIGHT:
+        case GIMP_LAYER_MODE_LINEAR_LIGHT:
+        case GIMP_LAYER_MODE_HARD_MIX:
+        case GIMP_LAYER_MODE_EXCLUSION:
+        case GIMP_LAYER_MODE_LINEAR_BURN:
+        case GIMP_LAYER_MODE_LUMA_DARKEN_ONLY:
+        case GIMP_LAYER_MODE_LUMA_LIGHTEN_ONLY:
+        case GIMP_LAYER_MODE_LUMINANCE:
+        case GIMP_LAYER_MODE_COLOR_ERASE:
+        case GIMP_LAYER_MODE_ERASE:
+        case GIMP_LAYER_MODE_MERGE:
+        case GIMP_LAYER_MODE_SPLIT:
+        case GIMP_LAYER_MODE_PASS_THROUGH:
+          gimp_enum_get_value (GIMP_TYPE_LAYER_MODE,
+                               gimp_layer_get_mode (layer),
+                               NULL, NULL, &enum_desc, NULL);
+          ADD_REASON (g_strdup_printf (_("Layer mode '%s' was added in %s"),
+                                       enum_desc, "GIMP 2.10"));
+          version = MAX (10, version);
+          break;
+
+          /*  Just here instead of default so we get compiler warnings  */
+        case GIMP_LAYER_MODE_REPLACE:
+        case GIMP_LAYER_MODE_ANTI_ERASE:
+        case GIMP_LAYER_MODE_SEPARATOR:
+          break;
+        }
+
+      /* need version 3 for layer trees */
+      if (gimp_viewable_get_children (GIMP_VIEWABLE (layer)))
+        {
+          ADD_REASON (g_strdup_printf (_("Layer groups were added in %s"),
+                                       "GIMP 2.8"));
+          version = MAX (3, version);
+
+          /* need version 13 for group layers with masks */
+          if (gimp_layer_get_mask (layer))
+            {
+              ADD_REASON (g_strdup_printf (_("Masks on layer groups were "
+                                             "added in %s"), "GIMP 2.10"));
+              version = MAX (13, version);
+            }
+        }
+    }
+
+  g_list_free (layers);
+
+  /* version 6 for new metadata has been dropped since they are
+   * saved through parasites, which is compatible with older versions.
+   */
+
+  /* need version 7 for != 8-bit gamma images */
+  if (gimp_image_get_precision (image) != GIMP_PRECISION_U8_GAMMA)
+    {
+      ADD_REASON (g_strdup_printf (_("High bit-depth images were added "
+                                     "in %s"), "GIMP 2.10"));
+      version = MAX (7, version);
+    }
+
+  /* need version 12 for > 8-bit images for proper endian swapping */
+  if (gimp_image_get_precision (image) > GIMP_PRECISION_U8_GAMMA)
+    version = MAX (12, version);
+
+  /* need version 8 for zlib compression */
+  if (zlib_compression)
+    {
+      ADD_REASON (g_strdup_printf (_("Internal zlib compression was "
+                                     "added in %s"), "GIMP 2.10"));
+      version = MAX (8, version);
+    }
+
+  /* if version is 10 (lots of new layer modes), go to version 11 with
+   * 64 bit offsets right away
+   */
+  if (version == 10)
+    version = 11;
+
+  /* use the image's in-memory size as an upper bound to estimate the
+   * need for 64 bit file offsets inside the XCF, this is a *very*
+   * conservative estimate and should never fail
+   */
+  if (gimp_object_get_memsize (GIMP_OBJECT (image), NULL) >= ((gint64) 1 << 32))
+    {
+      ADD_REASON (g_strdup_printf (_("Support for image files larger than "
+                                     "4GB was added in %s"), "GIMP 2.10"));
+      version = MAX (11, version);
+    }
+
+#undef ADD_REASON
+
+  switch (version)
+    {
+    case 0:
+    case 1:
+    case 2:
+      if (gimp_version)   *gimp_version   = 206;
+      if (version_string) *version_string = "GIMP 2.6";
+      break;
+
+    case 3:
+      if (gimp_version)   *gimp_version   = 208;
+      if (version_string) *version_string = "GIMP 2.8";
+      break;
+
+    case 4:
+    case 5:
+    case 6:
+    case 7:
+    case 8:
+    case 9:
+    case 10:
+    case 11:
+    case 12:
+    case 13:
+      if (gimp_version)   *gimp_version   = 210;
+      if (version_string) *version_string = "GIMP 2.10";
+      break;
+    }
+
+  if (version_reason && reasons)
+    {
+      GString *reason = g_string_new (NULL);
+
+      reasons = g_list_sort (reasons, (GCompareFunc) strcmp);
+
+      for (list = reasons; list; list = g_list_next (list))
+        {
+          g_string_append (reason, list->data);
+          if (g_list_next (list))
+            g_string_append_c (reason, '\n');
+        }
+
+      *version_reason = g_string_free (reason, FALSE);
+    }
+  if (reasons)
+    g_list_free_full (reasons, g_free);
+
+  return version;
+}
+
+void
+gimp_image_set_xcf_compression (GimpImage *image,
+                                gboolean   compression)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  GIMP_IMAGE_GET_PRIVATE (image)->xcf_compression = compression;
+}
+
+gboolean
+gimp_image_get_xcf_compression (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->xcf_compression;
+}
+
+void
+gimp_image_set_resolution (GimpImage *image,
+                           gdouble    xresolution,
+                           gdouble    yresolution)
+{
+  GimpImagePrivate *private;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  /* don't allow to set the resolution out of bounds */
+  if (xresolution < GIMP_MIN_RESOLUTION || xresolution > GIMP_MAX_RESOLUTION ||
+      yresolution < GIMP_MIN_RESOLUTION || yresolution > GIMP_MAX_RESOLUTION)
+    return;
+
+  private->resolution_set = TRUE;
+
+  if ((ABS (private->xresolution - xresolution) >= 1e-5) ||
+      (ABS (private->yresolution - yresolution) >= 1e-5))
+    {
+      gimp_image_undo_push_image_resolution (image,
+                                             C_("undo-type", "Change Image Resolution"));
+
+      private->xresolution = xresolution;
+      private->yresolution = yresolution;
+
+      gimp_image_resolution_changed (image);
+      gimp_image_size_changed_detailed (image,
+                                        0,
+                                        0,
+                                        gimp_image_get_width (image),
+                                        gimp_image_get_height (image));
+    }
+}
+
+void
+gimp_image_get_resolution (GimpImage *image,
+                           gdouble   *xresolution,
+                           gdouble   *yresolution)
+{
+  GimpImagePrivate *private;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (xresolution != NULL && yresolution != NULL);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  *xresolution = private->xresolution;
+  *yresolution = private->yresolution;
+}
+
+void
+gimp_image_resolution_changed (GimpImage *image)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  g_signal_emit (image, gimp_image_signals[RESOLUTION_CHANGED], 0);
+}
+
+void
+gimp_image_set_unit (GimpImage *image,
+                     GimpUnit   unit)
+{
+  GimpImagePrivate *private;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (unit > GIMP_UNIT_PIXEL);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  if (private->resolution_unit != unit)
+    {
+      gimp_image_undo_push_image_resolution (image,
+                                             C_("undo-type", "Change Image Unit"));
+
+      private->resolution_unit = unit;
+      gimp_image_unit_changed (image);
+    }
+}
+
+GimpUnit
+gimp_image_get_unit (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), GIMP_UNIT_INCH);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->resolution_unit;
+}
+
+void
+gimp_image_unit_changed (GimpImage *image)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  g_signal_emit (image, gimp_image_signals[UNIT_CHANGED], 0);
+}
+
+gint
+gimp_image_get_width (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), 0);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->width;
+}
+
+gint
+gimp_image_get_height (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), 0);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->height;
+}
+
+gboolean
+gimp_image_has_alpha (GimpImage *image)
+{
+  GimpImagePrivate *private;
+  GimpLayer        *layer;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), TRUE);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  layer = GIMP_LAYER (gimp_container_get_first_child (private->layers->container));
+
+  return ((gimp_image_get_n_layers (image) > 1) ||
+          (layer && gimp_drawable_has_alpha (GIMP_DRAWABLE (layer))));
+}
+
+gboolean
+gimp_image_is_empty (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), TRUE);
+
+  return gimp_container_is_empty (GIMP_IMAGE_GET_PRIVATE (image)->layers->container);
+}
+
+void
+gimp_image_set_floating_selection (GimpImage *image,
+                                   GimpLayer *floating_sel)
+{
+  GimpImagePrivate *private;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (floating_sel == NULL || GIMP_IS_LAYER (floating_sel));
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  if (private->floating_sel != floating_sel)
+    {
+      private->floating_sel = floating_sel;
+
+      private->flush_accum.floating_selection_changed = TRUE;
+    }
+}
+
+GimpLayer *
+gimp_image_get_floating_selection (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->floating_sel;
+}
+
+void
+gimp_image_floating_selection_changed (GimpImage *image)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  g_signal_emit (image, gimp_image_signals[FLOATING_SELECTION_CHANGED], 0);
+}
+
+GimpChannel *
+gimp_image_get_mask (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->selection_mask;
+}
+
+void
+gimp_image_mask_changed (GimpImage *image)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  g_signal_emit (image, gimp_image_signals[MASK_CHANGED], 0);
+}
+
+void
+gimp_image_take_mask (GimpImage   *image,
+                      GimpChannel *mask)
+{
+  GimpImagePrivate *private;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (GIMP_IS_SELECTION (mask));
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  if (private->selection_mask)
+    g_object_unref (private->selection_mask);
+
+  private->selection_mask = g_object_ref_sink (mask);
+
+  g_signal_connect (private->selection_mask, "update",
+                    G_CALLBACK (gimp_image_mask_update),
+                    image);
+}
+
+
+/*  image components  */
+
+const Babl *
+gimp_image_get_component_format (GimpImage       *image,
+                                 GimpChannelType  channel)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  switch (channel)
+    {
+    case GIMP_CHANNEL_RED:
+      return gimp_babl_component_format (GIMP_RGB,
+                                         gimp_image_get_precision (image),
+                                         RED);
+
+    case GIMP_CHANNEL_GREEN:
+      return gimp_babl_component_format (GIMP_RGB,
+                                         gimp_image_get_precision (image),
+                                         GREEN);
+
+    case GIMP_CHANNEL_BLUE:
+      return gimp_babl_component_format (GIMP_RGB,
+                                         gimp_image_get_precision (image),
+                                         BLUE);
+
+    case GIMP_CHANNEL_ALPHA:
+      return gimp_babl_component_format (GIMP_RGB,
+                                         gimp_image_get_precision (image),
+                                         ALPHA);
+
+    case GIMP_CHANNEL_GRAY:
+      return gimp_babl_component_format (GIMP_GRAY,
+                                         gimp_image_get_precision (image),
+                                         GRAY);
+
+    case GIMP_CHANNEL_INDEXED:
+      return babl_format ("Y u8"); /* will extract grayscale, the best
+                                    * we can do here */
+    }
+
+  return NULL;
+}
+
+gint
+gimp_image_get_component_index (GimpImage       *image,
+                                GimpChannelType  channel)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), -1);
+
+  switch (channel)
+    {
+    case GIMP_CHANNEL_RED:     return RED;
+    case GIMP_CHANNEL_GREEN:   return GREEN;
+    case GIMP_CHANNEL_BLUE:    return BLUE;
+    case GIMP_CHANNEL_GRAY:    return GRAY;
+    case GIMP_CHANNEL_INDEXED: return INDEXED;
+    case GIMP_CHANNEL_ALPHA:
+      switch (gimp_image_get_base_type (image))
+        {
+        case GIMP_RGB:     return ALPHA;
+        case GIMP_GRAY:    return ALPHA_G;
+        case GIMP_INDEXED: return ALPHA_I;
+        }
+    }
+
+  return -1;
+}
+
+void
+gimp_image_set_component_active (GimpImage       *image,
+                                 GimpChannelType  channel,
+                                 gboolean         active)
+{
+  GimpImagePrivate *private;
+  gint              index = -1;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  index = gimp_image_get_component_index (image, channel);
+
+  if (index != -1 && active != private->active[index])
+    {
+      private->active[index] = active ? TRUE : FALSE;
+
+      /*  If there is an active channel and we mess with the components,
+       *  the active channel gets unset...
+       */
+      gimp_image_unset_active_channel (image);
+
+      g_signal_emit (image,
+                     gimp_image_signals[COMPONENT_ACTIVE_CHANGED], 0,
+                     channel);
+    }
+}
+
+gboolean
+gimp_image_get_component_active (GimpImage       *image,
+                                 GimpChannelType  channel)
+{
+  gint index = -1;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+
+  index = gimp_image_get_component_index (image, channel);
+
+  if (index != -1)
+    return GIMP_IMAGE_GET_PRIVATE (image)->active[index];
+
+  return FALSE;
+}
+
+void
+gimp_image_get_active_array (GimpImage *image,
+                             gboolean  *components)
+{
+  GimpImagePrivate *private;
+  gint              i;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (components != NULL);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  for (i = 0; i < MAX_CHANNELS; i++)
+    components[i] = private->active[i];
+}
+
+GimpComponentMask
+gimp_image_get_active_mask (GimpImage *image)
+{
+  GimpImagePrivate  *private;
+  GimpComponentMask  mask = 0;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), 0);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  switch (gimp_image_get_base_type (image))
+    {
+    case GIMP_RGB:
+      mask |= (private->active[RED])   ? GIMP_COMPONENT_MASK_RED   : 0;
+      mask |= (private->active[GREEN]) ? GIMP_COMPONENT_MASK_GREEN : 0;
+      mask |= (private->active[BLUE])  ? GIMP_COMPONENT_MASK_BLUE  : 0;
+      mask |= (private->active[ALPHA]) ? GIMP_COMPONENT_MASK_ALPHA : 0;
+      break;
+
+    case GIMP_GRAY:
+    case GIMP_INDEXED:
+      mask |= (private->active[GRAY])    ? GIMP_COMPONENT_MASK_RED   : 0;
+      mask |= (private->active[GRAY])    ? GIMP_COMPONENT_MASK_GREEN : 0;
+      mask |= (private->active[GRAY])    ? GIMP_COMPONENT_MASK_BLUE  : 0;
+      mask |= (private->active[ALPHA_G]) ? GIMP_COMPONENT_MASK_ALPHA : 0;
+      break;
+    }
+
+  return mask;
+}
+
+void
+gimp_image_set_component_visible (GimpImage       *image,
+                                  GimpChannelType  channel,
+                                  gboolean         visible)
+{
+  GimpImagePrivate *private;
+  gint              index = -1;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  index = gimp_image_get_component_index (image, channel);
+
+  if (index != -1 && visible != private->visible[index])
+    {
+      private->visible[index] = visible ? TRUE : FALSE;
+
+      if (private->visible_mask)
+        {
+          GimpComponentMask mask;
+
+          mask = ~gimp_image_get_visible_mask (image) & GIMP_COMPONENT_MASK_ALL;
+
+          gegl_node_set (private->visible_mask,
+                         "mask", mask,
+                         NULL);
+        }
+
+      g_signal_emit (image,
+                     gimp_image_signals[COMPONENT_VISIBILITY_CHANGED], 0,
+                     channel);
+
+      gimp_image_invalidate_all (image);
+    }
+}
+
+gboolean
+gimp_image_get_component_visible (GimpImage       *image,
+                                  GimpChannelType  channel)
+{
+  gint index = -1;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+
+  index = gimp_image_get_component_index (image, channel);
+
+  if (index != -1)
+    return GIMP_IMAGE_GET_PRIVATE (image)->visible[index];
+
+  return FALSE;
+}
+
+void
+gimp_image_get_visible_array (GimpImage *image,
+                              gboolean  *components)
+{
+  GimpImagePrivate *private;
+  gint              i;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (components != NULL);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  for (i = 0; i < MAX_CHANNELS; i++)
+    components[i] = private->visible[i];
+}
+
+GimpComponentMask
+gimp_image_get_visible_mask (GimpImage *image)
+{
+  GimpImagePrivate  *private;
+  GimpComponentMask  mask = 0;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), 0);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  switch (gimp_image_get_base_type (image))
+    {
+    case GIMP_RGB:
+      mask |= (private->visible[RED])   ? GIMP_COMPONENT_MASK_RED   : 0;
+      mask |= (private->visible[GREEN]) ? GIMP_COMPONENT_MASK_GREEN : 0;
+      mask |= (private->visible[BLUE])  ? GIMP_COMPONENT_MASK_BLUE  : 0;
+      mask |= (private->visible[ALPHA]) ? GIMP_COMPONENT_MASK_ALPHA : 0;
+      break;
+
+    case GIMP_GRAY:
+    case GIMP_INDEXED:
+      mask |= (private->visible[GRAY])  ? GIMP_COMPONENT_MASK_RED   : 0;
+      mask |= (private->visible[GRAY])  ? GIMP_COMPONENT_MASK_GREEN : 0;
+      mask |= (private->visible[GRAY])  ? GIMP_COMPONENT_MASK_BLUE  : 0;
+      mask |= (private->visible[ALPHA]) ? GIMP_COMPONENT_MASK_ALPHA : 0;
+      break;
+    }
+
+  return mask;
+}
+
+
+/*  emitting image signals  */
+
+void
+gimp_image_mode_changed (GimpImage *image)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  g_signal_emit (image, gimp_image_signals[MODE_CHANGED], 0);
+}
+
+void
+gimp_image_precision_changed (GimpImage *image)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  g_signal_emit (image, gimp_image_signals[PRECISION_CHANGED], 0);
+}
+
+void
+gimp_image_alpha_changed (GimpImage *image)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  g_signal_emit (image, gimp_image_signals[ALPHA_CHANGED], 0);
+}
+
+void
+gimp_image_linked_items_changed (GimpImage *image)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  g_signal_emit (image, gimp_image_signals[LINKED_ITEMS_CHANGED], 0);
+}
+
+void
+gimp_image_invalidate (GimpImage *image,
+                       gint       x,
+                       gint       y,
+                       gint       width,
+                       gint       height)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  gimp_projectable_invalidate (GIMP_PROJECTABLE (image),
+                               x, y, width, height);
+
+  GIMP_IMAGE_GET_PRIVATE (image)->flush_accum.preview_invalidated = TRUE;
+}
+
+void
+gimp_image_invalidate_all (GimpImage *image)
+{
+  const GeglRectangle *bounding_box;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  bounding_box = &GIMP_IMAGE_GET_PRIVATE (image)->bounding_box;
+
+  gimp_image_invalidate (image,
+                         bounding_box->x,     bounding_box->y,
+                         bounding_box->width, bounding_box->height);
+}
+
+void
+gimp_image_guide_added (GimpImage *image,
+                        GimpGuide *guide)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (GIMP_IS_GUIDE (guide));
+
+  g_signal_emit (image, gimp_image_signals[GUIDE_ADDED], 0,
+                 guide);
+}
+
+void
+gimp_image_guide_removed (GimpImage *image,
+                          GimpGuide *guide)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (GIMP_IS_GUIDE (guide));
+
+  g_signal_emit (image, gimp_image_signals[GUIDE_REMOVED], 0,
+                 guide);
+}
+
+void
+gimp_image_guide_moved (GimpImage *image,
+                        GimpGuide *guide)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (GIMP_IS_GUIDE (guide));
+
+  g_signal_emit (image, gimp_image_signals[GUIDE_MOVED], 0,
+                 guide);
+}
+
+void
+gimp_image_sample_point_added (GimpImage       *image,
+                               GimpSamplePoint *sample_point)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (GIMP_IS_SAMPLE_POINT (sample_point));
+
+  g_signal_emit (image, gimp_image_signals[SAMPLE_POINT_ADDED], 0,
+                 sample_point);
+}
+
+void
+gimp_image_sample_point_removed (GimpImage       *image,
+                                 GimpSamplePoint *sample_point)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (GIMP_IS_SAMPLE_POINT (sample_point));
+
+  g_signal_emit (image, gimp_image_signals[SAMPLE_POINT_REMOVED], 0,
+                 sample_point);
+}
+
+void
+gimp_image_sample_point_moved (GimpImage       *image,
+                               GimpSamplePoint *sample_point)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (GIMP_IS_SAMPLE_POINT (sample_point));
+
+  g_signal_emit (image, gimp_image_signals[SAMPLE_POINT_MOVED], 0,
+                 sample_point);
+}
+
+/**
+ * gimp_image_size_changed_detailed:
+ * @image:
+ * @previous_origin_x:
+ * @previous_origin_y:
+ *
+ * Emits the size-changed-detailed signal that is typically used to adjust the
+ * position of the image in the display shell on various operations,
+ * e.g. crop.
+ *
+ * This function makes sure that GimpViewable::size-changed is also emitted.
+ **/
+void
+gimp_image_size_changed_detailed (GimpImage *image,
+                                  gint       previous_origin_x,
+                                  gint       previous_origin_y,
+                                  gint       previous_width,
+                                  gint       previous_height)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  g_signal_emit (image, gimp_image_signals[SIZE_CHANGED_DETAILED], 0,
+                 previous_origin_x,
+                 previous_origin_y,
+                 previous_width,
+                 previous_height);
+}
+
+void
+gimp_image_colormap_changed (GimpImage *image,
+                             gint       color_index)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (color_index >= -1 &&
+                    color_index < GIMP_IMAGE_GET_PRIVATE (image)->n_colors);
+
+  g_signal_emit (image, gimp_image_signals[COLORMAP_CHANGED], 0,
+                 color_index);
+}
+
+void
+gimp_image_selection_invalidate (GimpImage *image)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  g_signal_emit (image, gimp_image_signals[SELECTION_INVALIDATE], 0);
+}
+
+void
+gimp_image_quick_mask_changed (GimpImage *image)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  g_signal_emit (image, gimp_image_signals[QUICK_MASK_CHANGED], 0);
+}
+
+void
+gimp_image_undo_event (GimpImage     *image,
+                       GimpUndoEvent  event,
+                       GimpUndo      *undo)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (((event == GIMP_UNDO_EVENT_UNDO_FREE   ||
+                      event == GIMP_UNDO_EVENT_UNDO_FREEZE ||
+                      event == GIMP_UNDO_EVENT_UNDO_THAW) && undo == NULL) ||
+                    GIMP_IS_UNDO (undo));
+
+  g_signal_emit (image, gimp_image_signals[UNDO_EVENT], 0, event, undo);
+}
+
+
+/*  dirty counters  */
+
+/* NOTE about the image->dirty counter:
+ *   If 0, then the image is clean (ie, copy on disk is the same as the one
+ *      in memory).
+ *   If positive, then that's the number of dirtying operations done
+ *       on the image since the last save.
+ *   If negative, then user has hit undo and gone back in time prior
+ *       to the saved copy.  Hitting redo will eventually come back to
+ *       the saved copy.
+ *
+ *   The image is dirty (ie, needs saving) if counter is non-zero.
+ *
+ *   If the counter is around 100000, this is due to undo-ing back
+ *   before a saved version, then changing the image (thus destroying
+ *   the redo stack).  Once this has happened, it's impossible to get
+ *   the image back to the state on disk, since the redo info has been
+ *   freed.  See gimpimage-undo.c for the gory details.
+ */
+
+/*
+ * NEVER CALL gimp_image_dirty() directly!
+ *
+ * If your code has just dirtied the image, push an undo instead.
+ * Failing that, push the trivial undo which tells the user the
+ * command is not undoable: undo_push_cantundo() (But really, it would
+ * be best to push a proper undo).  If you just dirty the image
+ * without pushing an undo then the dirty count is increased, but
+ * popping that many undo actions won't lead to a clean image.
+ */
+
+gint
+gimp_image_dirty (GimpImage     *image,
+                  GimpDirtyMask  dirty_mask)
+{
+  GimpImagePrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  private->dirty++;
+  private->export_dirty++;
+
+  if (! private->dirty_time)
+    private->dirty_time = time (NULL);
+
+  g_signal_emit (image, gimp_image_signals[DIRTY], 0, dirty_mask);
+
+  TRC (("dirty %d -> %d\n", private->dirty - 1, private->dirty));
+
+  return private->dirty;
+}
+
+gint
+gimp_image_clean (GimpImage     *image,
+                  GimpDirtyMask  dirty_mask)
+{
+  GimpImagePrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  private->dirty--;
+  private->export_dirty--;
+
+  g_signal_emit (image, gimp_image_signals[CLEAN], 0, dirty_mask);
+
+  TRC (("clean %d -> %d\n", private->dirty + 1, private->dirty));
+
+  return private->dirty;
+}
+
+void
+gimp_image_clean_all (GimpImage *image)
+{
+  GimpImagePrivate *private;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  private->dirty      = 0;
+  private->dirty_time = 0;
+
+  g_signal_emit (image, gimp_image_signals[CLEAN], 0, GIMP_DIRTY_ALL);
+
+  gimp_object_name_changed (GIMP_OBJECT (image));
+}
+
+void
+gimp_image_export_clean_all (GimpImage *image)
+{
+  GimpImagePrivate *private;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  private->export_dirty = 0;
+
+  g_signal_emit (image, gimp_image_signals[CLEAN], 0, GIMP_DIRTY_ALL);
+
+  gimp_object_name_changed (GIMP_OBJECT (image));
+}
+
+/**
+ * gimp_image_is_dirty:
+ * @image:
+ *
+ * Returns: True if the image is dirty, false otherwise.
+ **/
+gint
+gimp_image_is_dirty (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->dirty != 0;
+}
+
+/**
+ * gimp_image_is_export_dirty:
+ * @image:
+ *
+ * Returns: True if the image export is dirty, false otherwise.
+ **/
+gboolean
+gimp_image_is_export_dirty (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->export_dirty != 0;
+}
+
+gint64
+gimp_image_get_dirty_time (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), 0);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->dirty_time;
+}
+
+/**
+ * gimp_image_saving:
+ * @image:
+ *
+ * Emits the "saving" signal, indicating that @image is about to be saved,
+ * or exported.
+ */
+void
+gimp_image_saving (GimpImage *image)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  g_signal_emit (image, gimp_image_signals[SAVING], 0);
+}
+
+/**
+ * gimp_image_saved:
+ * @image:
+ * @file:
+ *
+ * Emits the "saved" signal, indicating that @image was saved to the
+ * location specified by @file.
+ */
+void
+gimp_image_saved (GimpImage *image,
+                  GFile     *file)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (G_IS_FILE (file));
+
+  g_signal_emit (image, gimp_image_signals[SAVED], 0, file);
+}
+
+/**
+ * gimp_image_exported:
+ * @image:
+ * @file:
+ *
+ * Emits the "exported" signal, indicating that @image was exported to the
+ * location specified by @file.
+ */
+void
+gimp_image_exported (GimpImage *image,
+                     GFile     *file)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (G_IS_FILE (file));
+
+  g_signal_emit (image, gimp_image_signals[EXPORTED], 0, file);
+}
+
+
+/*  flush this image's displays  */
+
+void
+gimp_image_flush (GimpImage *image)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  gimp_projectable_flush (GIMP_PROJECTABLE (image),
+                          GIMP_IMAGE_GET_PRIVATE (image)->flush_accum.preview_invalidated);
+}
+
+
+/*  display / instance counters  */
+
+gint
+gimp_image_get_display_count (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), 0);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->disp_count;
+}
+
+void
+gimp_image_inc_display_count (GimpImage *image)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  GIMP_IMAGE_GET_PRIVATE (image)->disp_count++;
+}
+
+void
+gimp_image_dec_display_count (GimpImage *image)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  GIMP_IMAGE_GET_PRIVATE (image)->disp_count--;
+}
+
+gint
+gimp_image_get_instance_count (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), 0);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->instance_count;
+}
+
+void
+gimp_image_inc_instance_count (GimpImage *image)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  GIMP_IMAGE_GET_PRIVATE (image)->instance_count++;
+}
+
+void
+gimp_image_inc_show_all_count (GimpImage *image)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  GIMP_IMAGE_GET_PRIVATE (image)->show_all++;
+
+  if (GIMP_IMAGE_GET_PRIVATE (image)->show_all == 1)
+    {
+      g_clear_object (&GIMP_IMAGE_GET_PRIVATE (image)->pickable_buffer);
+
+      gimp_image_update_bounding_box (image);
+    }
+}
+
+void
+gimp_image_dec_show_all_count (GimpImage *image)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  GIMP_IMAGE_GET_PRIVATE (image)->show_all--;
+
+  if (GIMP_IMAGE_GET_PRIVATE (image)->show_all == 0)
+    {
+      g_clear_object (&GIMP_IMAGE_GET_PRIVATE (image)->pickable_buffer);
+
+      gimp_image_update_bounding_box (image);
+    }
+}
+
+
+/*  parasites  */
+
+const GimpParasite *
+gimp_image_parasite_find (GimpImage   *image,
+                          const gchar *name)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  return gimp_parasite_list_find (GIMP_IMAGE_GET_PRIVATE (image)->parasites,
+                                  name);
+}
+
+static void
+list_func (gchar          *key,
+           GimpParasite   *p,
+           gchar        ***cur)
+{
+  *(*cur)++ = (gchar *) g_strdup (key);
+}
+
+gchar **
+gimp_image_parasite_list (GimpImage *image,
+                          gint      *count)
+{
+  GimpImagePrivate  *private;
+  gchar            **list;
+  gchar            **cur;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  *count = gimp_parasite_list_length (private->parasites);
+  cur = list = g_new (gchar *, *count);
+
+  gimp_parasite_list_foreach (private->parasites, (GHFunc) list_func, &cur);
+
+  return list;
+}
+
+gboolean
+gimp_image_parasite_validate (GimpImage           *image,
+                              const GimpParasite  *parasite,
+                              GError             **error)
+{
+  const gchar *name;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+  g_return_val_if_fail (parasite != NULL, FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  name = gimp_parasite_name (parasite);
+
+  if (strcmp (name, GIMP_ICC_PROFILE_PARASITE_NAME) == 0)
+    {
+      return gimp_image_validate_icc_parasite (image, parasite, NULL, error);
+    }
+  else if (strcmp (name, "gimp-comment") == 0)
+    {
+      const gchar *data   = gimp_parasite_data (parasite);
+      gssize       length = gimp_parasite_data_size (parasite);
+      gboolean     valid  = FALSE;
+
+      if (length > 0)
+        {
+          if (data[length - 1] == '\0')
+            valid = g_utf8_validate (data, -1, NULL);
+          else
+            valid = g_utf8_validate (data, length, NULL);
+        }
+
+      if (! valid)
+        {
+          g_set_error (error, GIMP_ERROR, GIMP_FAILED,
+                       _("'gimp-comment' parasite validation failed: "
+                         "comment contains invalid UTF-8"));
+          return FALSE;
+        }
+    }
+
+  return TRUE;
+}
+
+void
+gimp_image_parasite_attach (GimpImage          *image,
+                            const GimpParasite *parasite,
+                            gboolean            push_undo)
+{
+  GimpImagePrivate *private;
+  GimpParasite      copy;
+  const gchar      *name;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (parasite != NULL);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  name = gimp_parasite_name (parasite);
+
+  /*  this is so ugly and is only for the PDB  */
+  if (strcmp (name, GIMP_ICC_PROFILE_PARASITE_NAME) == 0)
+    {
+      GimpColorProfile *profile;
+      GimpColorProfile *builtin;
+
+      profile =
+        gimp_color_profile_new_from_icc_profile (gimp_parasite_data (parasite),
+                                                 gimp_parasite_data_size (parasite),
+                                                 NULL);
+      builtin = gimp_image_get_builtin_color_profile (image);
+
+      if (gimp_color_profile_is_equal (profile, builtin))
+        {
+          /* setting the builtin profile is equal to removing the profile */
+          gimp_image_parasite_detach (image, GIMP_ICC_PROFILE_PARASITE_NAME,
+                                      push_undo);
+          g_object_unref (profile);
+          return;
+        }
+
+      g_object_unref (profile);
+    }
+
+  /*  make a temporary copy of the GimpParasite struct because
+   *  gimp_parasite_shift_parent() changes it
+   */
+  copy = *parasite;
+
+  /*  only set the dirty bit manually if we can be saved and the new
+   *  parasite differs from the current one and we aren't undoable
+   */
+  if (push_undo && gimp_parasite_is_undoable (&copy))
+    gimp_image_undo_push_image_parasite (image,
+                                         C_("undo-type", "Attach Parasite to Image"),
+                                         &copy);
+
+  /*  We used to push a cantundo on the stack here. This made the undo stack
+   *  unusable (NULL on the stack) and prevented people from undoing after a
+   *  save (since most save plug-ins attach an undoable comment parasite).
+   *  Now we simply attach the parasite without pushing an undo. That way
+   *  it's undoable but does not block the undo system.   --Sven
+   */
+  gimp_parasite_list_add (private->parasites, &copy);
+
+  if (push_undo && gimp_parasite_has_flag (&copy, GIMP_PARASITE_ATTACH_PARENT))
+    {
+      gimp_parasite_shift_parent (&copy);
+      gimp_parasite_attach (image->gimp, &copy);
+    }
+
+  if (strcmp (name, GIMP_ICC_PROFILE_PARASITE_NAME) == 0)
+    _gimp_image_update_color_profile (image, parasite);
+
+  g_signal_emit (image, gimp_image_signals[PARASITE_ATTACHED], 0,
+                 name);
+}
+
+void
+gimp_image_parasite_detach (GimpImage   *image,
+                            const gchar *name,
+                            gboolean     push_undo)
+{
+  GimpImagePrivate   *private;
+  const GimpParasite *parasite;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (name != NULL);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  if (! (parasite = gimp_parasite_list_find (private->parasites, name)))
+    return;
+
+  if (push_undo && gimp_parasite_is_undoable (parasite))
+    gimp_image_undo_push_image_parasite_remove (image,
+                                                C_("undo-type", "Remove Parasite from Image"),
+                                                name);
+
+  gimp_parasite_list_remove (private->parasites, name);
+
+  if (strcmp (name, GIMP_ICC_PROFILE_PARASITE_NAME) == 0)
+    _gimp_image_update_color_profile (image, NULL);
+
+  g_signal_emit (image, gimp_image_signals[PARASITE_DETACHED], 0,
+                 name);
+}
+
+
+/*  tattoos  */
+
+GimpTattoo
+gimp_image_get_new_tattoo (GimpImage *image)
+{
+  GimpImagePrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), 0);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  private->tattoo_state++;
+
+  if (G_UNLIKELY (private->tattoo_state == 0))
+    g_warning ("%s: Tattoo state corrupted (integer overflow).", G_STRFUNC);
+
+  return private->tattoo_state;
+}
+
+GimpTattoo
+gimp_image_get_tattoo_state (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), 0);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->tattoo_state;
+}
+
+gboolean
+gimp_image_set_tattoo_state (GimpImage  *image,
+                             GimpTattoo  val)
+{
+  GList      *all_items;
+  GList      *list;
+  gboolean    retval = TRUE;
+  GimpTattoo  maxval = 0;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+
+  /* Check that the layer tattoos don't overlap with channel or vector ones */
+  all_items = gimp_image_get_layer_list (image);
+
+  for (list = all_items; list; list = g_list_next (list))
+    {
+      GimpTattoo ltattoo;
+
+      ltattoo = gimp_item_get_tattoo (GIMP_ITEM (list->data));
+      if (ltattoo > maxval)
+        maxval = ltattoo;
+
+      if (gimp_image_get_channel_by_tattoo (image, ltattoo))
+        retval = FALSE; /* Oopps duplicated tattoo in channel */
+
+      if (gimp_image_get_vectors_by_tattoo (image, ltattoo))
+        retval = FALSE; /* Oopps duplicated tattoo in vectors */
+    }
+
+  g_list_free (all_items);
+
+  /* Now check that the channel and vectors tattoos don't overlap */
+  all_items = gimp_image_get_channel_list (image);
+
+  for (list = all_items; list; list = g_list_next (list))
+    {
+      GimpTattoo ctattoo;
+
+      ctattoo = gimp_item_get_tattoo (GIMP_ITEM (list->data));
+      if (ctattoo > maxval)
+        maxval = ctattoo;
+
+      if (gimp_image_get_vectors_by_tattoo (image, ctattoo))
+        retval = FALSE; /* Oopps duplicated tattoo in vectors */
+    }
+
+  g_list_free (all_items);
+
+  /* Find the max tattoo value in the vectors */
+  all_items = gimp_image_get_vectors_list (image);
+
+  for (list = all_items; list; list = g_list_next (list))
+    {
+      GimpTattoo vtattoo;
+
+      vtattoo = gimp_item_get_tattoo (GIMP_ITEM (list->data));
+      if (vtattoo > maxval)
+        maxval = vtattoo;
+    }
+
+  g_list_free (all_items);
+
+  if (val < maxval)
+    retval = FALSE;
+
+  /* Must check if the state is valid */
+  if (retval == TRUE)
+    GIMP_IMAGE_GET_PRIVATE (image)->tattoo_state = val;
+
+  return retval;
+}
+
+
+/*  projection  */
+
+GimpProjection *
+gimp_image_get_projection (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->projection;
+}
+
+
+/*  layers / channels / vectors  */
+
+GimpItemTree *
+gimp_image_get_layer_tree (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->layers;
+}
+
+GimpItemTree *
+gimp_image_get_channel_tree (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->channels;
+}
+
+GimpItemTree *
+gimp_image_get_vectors_tree (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->vectors;
+}
+
+GimpContainer *
+gimp_image_get_layers (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->layers->container;
+}
+
+GimpContainer *
+gimp_image_get_channels (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->channels->container;
+}
+
+GimpContainer *
+gimp_image_get_vectors (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  return GIMP_IMAGE_GET_PRIVATE (image)->vectors->container;
+}
+
+gint
+gimp_image_get_n_layers (GimpImage *image)
+{
+  GimpItemStack *stack;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), 0);
+
+  stack = GIMP_ITEM_STACK (gimp_image_get_layers (image));
+
+  return gimp_item_stack_get_n_items (stack);
+}
+
+gint
+gimp_image_get_n_channels (GimpImage *image)
+{
+  GimpItemStack *stack;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), 0);
+
+  stack = GIMP_ITEM_STACK (gimp_image_get_channels (image));
+
+  return gimp_item_stack_get_n_items (stack);
+}
+
+gint
+gimp_image_get_n_vectors (GimpImage *image)
+{
+  GimpItemStack *stack;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), 0);
+
+  stack = GIMP_ITEM_STACK (gimp_image_get_vectors (image));
+
+  return gimp_item_stack_get_n_items (stack);
+}
+
+GList *
+gimp_image_get_layer_iter (GimpImage *image)
+{
+  GimpItemStack *stack;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  stack = GIMP_ITEM_STACK (gimp_image_get_layers (image));
+
+  return gimp_item_stack_get_item_iter (stack);
+}
+
+GList *
+gimp_image_get_channel_iter (GimpImage *image)
+{
+  GimpItemStack *stack;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  stack = GIMP_ITEM_STACK (gimp_image_get_channels (image));
+
+  return gimp_item_stack_get_item_iter (stack);
+}
+
+GList *
+gimp_image_get_vectors_iter (GimpImage *image)
+{
+  GimpItemStack *stack;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  stack = GIMP_ITEM_STACK (gimp_image_get_vectors (image));
+
+  return gimp_item_stack_get_item_iter (stack);
+}
+
+GList *
+gimp_image_get_layer_list (GimpImage *image)
+{
+  GimpItemStack *stack;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  stack = GIMP_ITEM_STACK (gimp_image_get_layers (image));
+
+  return gimp_item_stack_get_item_list (stack);
+}
+
+GList *
+gimp_image_get_channel_list (GimpImage *image)
+{
+  GimpItemStack *stack;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  stack = GIMP_ITEM_STACK (gimp_image_get_channels (image));
+
+  return gimp_item_stack_get_item_list (stack);
+}
+
+GList *
+gimp_image_get_vectors_list (GimpImage *image)
+{
+  GimpItemStack *stack;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  stack = GIMP_ITEM_STACK (gimp_image_get_vectors (image));
+
+  return gimp_item_stack_get_item_list (stack);
+}
+
+
+/*  active drawable, layer, channel, vectors  */
+
+GimpDrawable *
+gimp_image_get_active_drawable (GimpImage *image)
+{
+  GimpImagePrivate *private;
+  GimpItem         *active_channel;
+  GimpItem         *active_layer;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  active_channel = gimp_item_tree_get_active_item (private->channels);
+  active_layer   = gimp_item_tree_get_active_item (private->layers);
+
+  /*  If there is an active channel (a saved selection, etc.),
+   *  we ignore the active layer
+   */
+  if (active_channel)
+    {
+      return GIMP_DRAWABLE (active_channel);
+    }
+  else if (active_layer)
+    {
+      GimpLayer     *layer = GIMP_LAYER (active_layer);
+      GimpLayerMask *mask  = gimp_layer_get_mask (layer);
+
+      if (mask && gimp_layer_get_edit_mask (layer))
+        return GIMP_DRAWABLE (mask);
+      else
+        return GIMP_DRAWABLE (layer);
+    }
+
+  return NULL;
+}
+
+GimpLayer *
+gimp_image_get_active_layer (GimpImage *image)
+{
+  GimpImagePrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  return GIMP_LAYER (gimp_item_tree_get_active_item (private->layers));
+}
+
+GimpChannel *
+gimp_image_get_active_channel (GimpImage *image)
+{
+  GimpImagePrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  return GIMP_CHANNEL (gimp_item_tree_get_active_item (private->channels));
+}
+
+GimpVectors *
+gimp_image_get_active_vectors (GimpImage *image)
+{
+  GimpImagePrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  return GIMP_VECTORS (gimp_item_tree_get_active_item (private->vectors));
+}
+
+GimpLayer *
+gimp_image_set_active_layer (GimpImage *image,
+                             GimpLayer *layer)
+{
+  GimpImagePrivate *private;
+  GimpLayer        *floating_sel;
+  GimpLayer        *active_layer;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (layer == NULL || GIMP_IS_LAYER (layer), NULL);
+  g_return_val_if_fail (layer == NULL ||
+                        (gimp_item_is_attached (GIMP_ITEM (layer)) &&
+                         gimp_item_get_image (GIMP_ITEM (layer)) == image),
+                        NULL);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  floating_sel = gimp_image_get_floating_selection (image);
+
+  /*  Make sure the floating_sel always is the active layer  */
+  if (floating_sel && layer != floating_sel)
+    return floating_sel;
+
+  active_layer = gimp_image_get_active_layer (image);
+
+  if (layer != active_layer)
+    {
+      /*  Don't cache selection info for the previous active layer  */
+      if (active_layer)
+        gimp_drawable_invalidate_boundary (GIMP_DRAWABLE (active_layer));
+
+      gimp_item_tree_set_active_item (private->layers, GIMP_ITEM (layer));
+    }
+
+  return gimp_image_get_active_layer (image);
+}
+
+GimpChannel *
+gimp_image_set_active_channel (GimpImage   *image,
+                               GimpChannel *channel)
+{
+  GimpImagePrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (channel == NULL || GIMP_IS_CHANNEL (channel), NULL);
+  g_return_val_if_fail (channel == NULL ||
+                        (gimp_item_is_attached (GIMP_ITEM (channel)) &&
+                         gimp_item_get_image (GIMP_ITEM (channel)) == image),
+                        NULL);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  /*  Not if there is a floating selection  */
+  if (channel && gimp_image_get_floating_selection (image))
+    return NULL;
+
+  if (channel != gimp_image_get_active_channel (image))
+    {
+      gimp_item_tree_set_active_item (private->channels, GIMP_ITEM (channel));
+    }
+
+  return gimp_image_get_active_channel (image);
+}
+
+GimpChannel *
+gimp_image_unset_active_channel (GimpImage *image)
+{
+  GimpImagePrivate *private;
+  GimpChannel      *channel;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  channel = gimp_image_get_active_channel (image);
+
+  if (channel)
+    {
+      gimp_image_set_active_channel (image, NULL);
+
+      if (private->layer_stack)
+        gimp_image_set_active_layer (image, private->layer_stack->data);
+    }
+
+  return channel;
+}
+
+GimpVectors *
+gimp_image_set_active_vectors (GimpImage   *image,
+                               GimpVectors *vectors)
+{
+  GimpImagePrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (vectors == NULL || GIMP_IS_VECTORS (vectors), NULL);
+  g_return_val_if_fail (vectors == NULL ||
+                        (gimp_item_is_attached (GIMP_ITEM (vectors)) &&
+                         gimp_item_get_image (GIMP_ITEM (vectors)) == image),
+                        NULL);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  if (vectors != gimp_image_get_active_vectors (image))
+    {
+      gimp_item_tree_set_active_item (private->vectors, GIMP_ITEM (vectors));
+    }
+
+  return gimp_image_get_active_vectors (image);
+}
+
+
+/*  layer, channel, vectors by tattoo  */
+
+GimpLayer *
+gimp_image_get_layer_by_tattoo (GimpImage  *image,
+                                GimpTattoo  tattoo)
+{
+  GimpItemStack *stack;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  stack = GIMP_ITEM_STACK (gimp_image_get_layers (image));
+
+  return GIMP_LAYER (gimp_item_stack_get_item_by_tattoo (stack, tattoo));
+}
+
+GimpChannel *
+gimp_image_get_channel_by_tattoo (GimpImage  *image,
+                                  GimpTattoo  tattoo)
+{
+  GimpItemStack *stack;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  stack = GIMP_ITEM_STACK (gimp_image_get_channels (image));
+
+  return GIMP_CHANNEL (gimp_item_stack_get_item_by_tattoo (stack, tattoo));
+}
+
+GimpVectors *
+gimp_image_get_vectors_by_tattoo (GimpImage  *image,
+                                  GimpTattoo  tattoo)
+{
+  GimpItemStack *stack;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  stack = GIMP_ITEM_STACK (gimp_image_get_vectors (image));
+
+  return GIMP_VECTORS (gimp_item_stack_get_item_by_tattoo (stack, tattoo));
+}
+
+
+/*  layer, channel, vectors by name  */
+
+GimpLayer *
+gimp_image_get_layer_by_name (GimpImage   *image,
+                              const gchar *name)
+{
+  GimpItemTree *tree;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (name != NULL, NULL);
+
+  tree = gimp_image_get_layer_tree (image);
+
+  return GIMP_LAYER (gimp_item_tree_get_item_by_name (tree, name));
+}
+
+GimpChannel *
+gimp_image_get_channel_by_name (GimpImage   *image,
+                                const gchar *name)
+{
+  GimpItemTree *tree;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (name != NULL, NULL);
+
+  tree = gimp_image_get_channel_tree (image);
+
+  return GIMP_CHANNEL (gimp_item_tree_get_item_by_name (tree, name));
+}
+
+GimpVectors *
+gimp_image_get_vectors_by_name (GimpImage   *image,
+                                const gchar *name)
+{
+  GimpItemTree *tree;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (name != NULL, NULL);
+
+  tree = gimp_image_get_vectors_tree (image);
+
+  return GIMP_VECTORS (gimp_item_tree_get_item_by_name (tree, name));
+}
+
+
+/*  items  */
+
+gboolean
+gimp_image_reorder_item (GimpImage   *image,
+                         GimpItem    *item,
+                         GimpItem    *new_parent,
+                         gint         new_index,
+                         gboolean     push_undo,
+                         const gchar *undo_desc)
+{
+  GimpItemTree *tree;
+  gboolean      result;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+  g_return_val_if_fail (GIMP_IS_ITEM (item), FALSE);
+  g_return_val_if_fail (gimp_item_get_image (item) == image, FALSE);
+
+  tree = gimp_item_get_tree (item);
+
+  g_return_val_if_fail (tree != NULL, FALSE);
+
+  if (push_undo)
+    {
+      if (! undo_desc)
+        undo_desc = GIMP_ITEM_GET_CLASS (item)->reorder_desc;
+
+      gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_IMAGE_ITEM_REORDER,
+                                   undo_desc);
+    }
+
+  gimp_image_freeze_bounding_box (image);
+
+  gimp_item_start_move (item, push_undo);
+
+  /*  item and new_parent are type-checked in GimpItemTree
+   */
+  result = gimp_item_tree_reorder_item (tree, item,
+                                        new_parent, new_index,
+                                        push_undo, undo_desc);
+
+  gimp_item_end_move (item, push_undo);
+
+  gimp_image_thaw_bounding_box (image);
+
+  if (push_undo)
+    gimp_image_undo_group_end (image);
+
+  return result;
+}
+
+gboolean
+gimp_image_raise_item (GimpImage *image,
+                       GimpItem  *item,
+                       GError    **error)
+{
+  gint index;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+  g_return_val_if_fail (GIMP_IS_ITEM (item), FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  index = gimp_item_get_index (item);
+
+  g_return_val_if_fail (index != -1, FALSE);
+
+  if (index == 0)
+    {
+      g_set_error_literal (error,  GIMP_ERROR, GIMP_FAILED,
+                           GIMP_ITEM_GET_CLASS (item)->raise_failed);
+      return FALSE;
+    }
+
+  return gimp_image_reorder_item (image, item,
+                                  gimp_item_get_parent (item), index - 1,
+                                  TRUE, GIMP_ITEM_GET_CLASS (item)->raise_desc);
+}
+
+gboolean
+gimp_image_raise_item_to_top (GimpImage *image,
+                              GimpItem  *item)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+  g_return_val_if_fail (GIMP_IS_ITEM (item), FALSE);
+
+  return gimp_image_reorder_item (image, item,
+                                  gimp_item_get_parent (item), 0,
+                                  TRUE, GIMP_ITEM_GET_CLASS (item)->raise_to_top_desc);
+}
+
+gboolean
+gimp_image_lower_item (GimpImage *image,
+                       GimpItem  *item,
+                       GError    **error)
+{
+  GimpContainer *container;
+  gint           index;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+  g_return_val_if_fail (GIMP_IS_ITEM (item), FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  container = gimp_item_get_container (item);
+
+  g_return_val_if_fail (container != NULL, FALSE);
+
+  index = gimp_item_get_index (item);
+
+  if (index == gimp_container_get_n_children (container) - 1)
+    {
+      g_set_error_literal (error, GIMP_ERROR, GIMP_FAILED,
+                           GIMP_ITEM_GET_CLASS (item)->lower_failed);
+      return FALSE;
+    }
+
+  return gimp_image_reorder_item (image, item,
+                                  gimp_item_get_parent (item), index + 1,
+                                  TRUE, GIMP_ITEM_GET_CLASS (item)->lower_desc);
+}
+
+gboolean
+gimp_image_lower_item_to_bottom (GimpImage *image,
+                                  GimpItem *item)
+{
+  GimpContainer *container;
+  gint           length;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+  g_return_val_if_fail (GIMP_IS_ITEM (item), FALSE);
+
+  container = gimp_item_get_container (item);
+
+  g_return_val_if_fail (container != NULL, FALSE);
+
+  length = gimp_container_get_n_children (container);
+
+  return gimp_image_reorder_item (image, item,
+                                  gimp_item_get_parent (item), length - 1,
+                                  TRUE, GIMP_ITEM_GET_CLASS (item)->lower_to_bottom_desc);
+}
+
+
+/*  layers  */
+
+gboolean
+gimp_image_add_layer (GimpImage *image,
+                      GimpLayer *layer,
+                      GimpLayer *parent,
+                      gint       position,
+                      gboolean   push_undo)
+{
+  GimpImagePrivate *private;
+  gboolean          old_has_alpha;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  /*  item and parent are type-checked in GimpItemTree
+   */
+  if (! gimp_item_tree_get_insert_pos (private->layers,
+                                       (GimpItem *) layer,
+                                       (GimpItem **) &parent,
+                                       &position))
+    return FALSE;
+
+  gimp_image_unset_default_new_layer_mode (image);
+
+  /*  If there is a floating selection (and this isn't it!),
+   *  make sure the insert position is greater than 0
+   */
+  if (parent == NULL && position == 0 &&
+      gimp_image_get_floating_selection (image))
+    position = 1;
+
+  old_has_alpha = gimp_image_has_alpha (image);
+
+  if (push_undo)
+    gimp_image_undo_push_layer_add (image, C_("undo-type", "Add Layer"),
+                                    layer,
+                                    gimp_image_get_active_layer (image));
+
+  gimp_item_tree_add_item (private->layers, GIMP_ITEM (layer),
+                           GIMP_ITEM (parent), position);
+
+  gimp_image_set_active_layer (image, layer);
+
+  /*  If the layer is a floating selection, attach it to the drawable  */
+  if (gimp_layer_is_floating_sel (layer))
+    gimp_drawable_attach_floating_sel (gimp_layer_get_floating_sel_drawable (layer),
+                                       layer);
+
+  if (old_has_alpha != gimp_image_has_alpha (image))
+    private->flush_accum.alpha_changed = TRUE;
+
+  return TRUE;
+}
+
+void
+gimp_image_remove_layer (GimpImage *image,
+                         GimpLayer *layer,
+                         gboolean   push_undo,
+                         GimpLayer *new_active)
+{
+  GimpImagePrivate *private;
+  GimpLayer        *active_layer;
+  gboolean          old_has_alpha;
+  const gchar      *undo_desc;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (GIMP_IS_LAYER (layer));
+  g_return_if_fail (gimp_item_is_attached (GIMP_ITEM (layer)));
+  g_return_if_fail (gimp_item_get_image (GIMP_ITEM (layer)) == image);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  gimp_image_unset_default_new_layer_mode (image);
+
+  if (push_undo)
+    gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_IMAGE_ITEM_REMOVE,
+                                 C_("undo-type", "Remove Layer"));
+
+  gimp_item_start_move (GIMP_ITEM (layer), push_undo);
+
+  if (gimp_drawable_get_floating_sel (GIMP_DRAWABLE (layer)))
+    {
+      if (! push_undo)
+        {
+          g_warning ("%s() was called from an undo function while the layer "
+                     "had a floating selection. Please report this at "
+                     "https://www.gimp.org/bugs/", G_STRFUNC);
+          return;
+        }
+
+      gimp_image_remove_layer (image,
+                               gimp_drawable_get_floating_sel (GIMP_DRAWABLE (layer)),
+                               TRUE, NULL);
+    }
+
+  active_layer = gimp_image_get_active_layer (image);
+
+  old_has_alpha = gimp_image_has_alpha (image);
+
+  if (gimp_layer_is_floating_sel (layer))
+    {
+      undo_desc = C_("undo-type", "Remove Floating Selection");
+
+      gimp_drawable_detach_floating_sel (gimp_layer_get_floating_sel_drawable (layer));
+    }
+  else
+    {
+      undo_desc = C_("undo-type", "Remove Layer");
+    }
+
+  if (push_undo)
+    gimp_image_undo_push_layer_remove (image, undo_desc, layer,
+                                       gimp_layer_get_parent (layer),
+                                       gimp_item_get_index (GIMP_ITEM (layer)),
+                                       active_layer);
+
+  g_object_ref (layer);
+
+  /*  Make sure we're not caching any old selection info  */
+  if (layer == active_layer)
+    gimp_drawable_invalidate_boundary (GIMP_DRAWABLE (layer));
+
+  private->layer_stack = g_slist_remove (private->layer_stack, layer);
+
+  /*  Also remove all children of a group layer from the layer_stack  */
+  if (gimp_viewable_get_children (GIMP_VIEWABLE (layer)))
+    {
+      GimpContainer *stack = gimp_viewable_get_children (GIMP_VIEWABLE (layer));
+      GList         *children;
+      GList         *list;
+
+      children = gimp_item_stack_get_item_list (GIMP_ITEM_STACK (stack));
+
+      for (list = children; list; list = g_list_next (list))
+        {
+          private->layer_stack = g_slist_remove (private->layer_stack,
+                                                 list->data);
+        }
+
+      g_list_free (children);
+    }
+
+  new_active =
+    GIMP_LAYER (gimp_item_tree_remove_item (private->layers,
+                                            GIMP_ITEM (layer),
+                                            GIMP_ITEM (new_active)));
+
+  if (gimp_layer_is_floating_sel (layer))
+    {
+      /*  If this was the floating selection, activate the underlying drawable
+       */
+      floating_sel_activate_drawable (layer);
+    }
+  else if (active_layer &&
+           (layer == active_layer ||
+            gimp_viewable_is_ancestor (GIMP_VIEWABLE (layer),
+                                       GIMP_VIEWABLE (active_layer))))
+    {
+      gimp_image_set_active_layer (image, new_active);
+    }
+
+  gimp_item_end_move (GIMP_ITEM (layer), push_undo);
+
+  g_object_unref (layer);
+
+  if (old_has_alpha != gimp_image_has_alpha (image))
+    private->flush_accum.alpha_changed = TRUE;
+
+  if (push_undo)
+    gimp_image_undo_group_end (image);
+}
+
+void
+gimp_image_add_layers (GimpImage   *image,
+                       GList       *layers,
+                       GimpLayer   *parent,
+                       gint         position,
+                       gint         x,
+                       gint         y,
+                       gint         width,
+                       gint         height,
+                       const gchar *undo_desc)
+{
+  GimpImagePrivate *private;
+  GList            *list;
+  gint              layers_x      = G_MAXINT;
+  gint              layers_y      = G_MAXINT;
+  gint              layers_width  = 0;
+  gint              layers_height = 0;
+  gint              offset_x;
+  gint              offset_y;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (layers != NULL);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  /*  item and parent are type-checked in GimpItemTree
+   */
+  if (! gimp_item_tree_get_insert_pos (private->layers,
+                                       (GimpItem *) layers->data,
+                                       (GimpItem **) &parent,
+                                       &position))
+    return;
+
+  for (list = layers; list; list = g_list_next (list))
+    {
+      GimpItem *item = GIMP_ITEM (list->data);
+      gint      off_x, off_y;
+
+      gimp_item_get_offset (item, &off_x, &off_y);
+
+      layers_x = MIN (layers_x, off_x);
+      layers_y = MIN (layers_y, off_y);
+
+      layers_width  = MAX (layers_width,
+                           off_x + gimp_item_get_width (item)  - layers_x);
+      layers_height = MAX (layers_height,
+                           off_y + gimp_item_get_height (item) - layers_y);
+    }
+
+  offset_x = x + (width  - layers_width)  / 2 - layers_x;
+  offset_y = y + (height - layers_height) / 2 - layers_y;
+
+  gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_LAYER_ADD, undo_desc);
+
+  for (list = layers; list; list = g_list_next (list))
+    {
+      GimpItem *new_item = GIMP_ITEM (list->data);
+
+      gimp_item_translate (new_item, offset_x, offset_y, FALSE);
+
+      gimp_image_add_layer (image, GIMP_LAYER (new_item),
+                            parent, position, TRUE);
+      position++;
+    }
+
+  if (layers)
+    gimp_image_set_active_layer (image, layers->data);
+
+  gimp_image_undo_group_end (image);
+}
+
+
+/*  channels  */
+
+gboolean
+gimp_image_add_channel (GimpImage   *image,
+                        GimpChannel *channel,
+                        GimpChannel *parent,
+                        gint         position,
+                        gboolean     push_undo)
+{
+  GimpImagePrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  /*  item and parent are type-checked in GimpItemTree
+   */
+  if (! gimp_item_tree_get_insert_pos (private->channels,
+                                       (GimpItem *) channel,
+                                       (GimpItem **) &parent,
+                                       &position))
+    return FALSE;
+
+  if (push_undo)
+    gimp_image_undo_push_channel_add (image, C_("undo-type", "Add Channel"),
+                                      channel,
+                                      gimp_image_get_active_channel (image));
+
+  gimp_item_tree_add_item (private->channels, GIMP_ITEM (channel),
+                           GIMP_ITEM (parent), position);
+
+  gimp_image_set_active_channel (image, channel);
+
+  return TRUE;
+}
+
+void
+gimp_image_remove_channel (GimpImage   *image,
+                           GimpChannel *channel,
+                           gboolean     push_undo,
+                           GimpChannel *new_active)
+{
+  GimpImagePrivate *private;
+  GimpChannel      *active_channel;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (GIMP_IS_CHANNEL (channel));
+  g_return_if_fail (gimp_item_is_attached (GIMP_ITEM (channel)));
+  g_return_if_fail (gimp_item_get_image (GIMP_ITEM (channel)) == image);
+
+  if (push_undo)
+    gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_IMAGE_ITEM_REMOVE,
+                                 C_("undo-type", "Remove Channel"));
+
+  gimp_item_start_move (GIMP_ITEM (channel), push_undo);
+
+  if (gimp_drawable_get_floating_sel (GIMP_DRAWABLE (channel)))
+    {
+      if (! push_undo)
+        {
+          g_warning ("%s() was called from an undo function while the channel "
+                     "had a floating selection. Please report this at "
+                     "https://www.gimp.org/bugs/", G_STRFUNC);
+          return;
+        }
+
+      gimp_image_remove_layer (image,
+                               gimp_drawable_get_floating_sel (GIMP_DRAWABLE (channel)),
+                               TRUE, NULL);
+    }
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  active_channel = gimp_image_get_active_channel (image);
+
+  if (push_undo)
+    gimp_image_undo_push_channel_remove (image, C_("undo-type", "Remove Channel"), channel,
+                                         gimp_channel_get_parent (channel),
+                                         gimp_item_get_index (GIMP_ITEM (channel)),
+                                         active_channel);
+
+  g_object_ref (channel);
+
+  new_active =
+    GIMP_CHANNEL (gimp_item_tree_remove_item (private->channels,
+                                              GIMP_ITEM (channel),
+                                              GIMP_ITEM (new_active)));
+
+  if (active_channel &&
+      (channel == active_channel ||
+       gimp_viewable_is_ancestor (GIMP_VIEWABLE (channel),
+                                  GIMP_VIEWABLE (active_channel))))
+    {
+      if (new_active)
+        gimp_image_set_active_channel (image, new_active);
+      else
+        gimp_image_unset_active_channel (image);
+    }
+
+  gimp_item_end_move (GIMP_ITEM (channel), push_undo);
+
+  g_object_unref (channel);
+
+  if (push_undo)
+    gimp_image_undo_group_end (image);
+}
+
+
+/*  vectors  */
+
+gboolean
+gimp_image_add_vectors (GimpImage   *image,
+                        GimpVectors *vectors,
+                        GimpVectors *parent,
+                        gint         position,
+                        gboolean     push_undo)
+{
+  GimpImagePrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  /*  item and parent are type-checked in GimpItemTree
+   */
+  if (! gimp_item_tree_get_insert_pos (private->vectors,
+                                       (GimpItem *) vectors,
+                                       (GimpItem **) &parent,
+                                       &position))
+    return FALSE;
+
+  if (push_undo)
+    gimp_image_undo_push_vectors_add (image, C_("undo-type", "Add Path"),
+                                      vectors,
+                                      gimp_image_get_active_vectors (image));
+
+  gimp_item_tree_add_item (private->vectors, GIMP_ITEM (vectors),
+                           GIMP_ITEM (parent), position);
+
+  gimp_image_set_active_vectors (image, vectors);
+
+  return TRUE;
+}
+
+void
+gimp_image_remove_vectors (GimpImage   *image,
+                           GimpVectors *vectors,
+                           gboolean     push_undo,
+                           GimpVectors *new_active)
+{
+  GimpImagePrivate *private;
+  GimpVectors      *active_vectors;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+  g_return_if_fail (GIMP_IS_VECTORS (vectors));
+  g_return_if_fail (gimp_item_is_attached (GIMP_ITEM (vectors)));
+  g_return_if_fail (gimp_item_get_image (GIMP_ITEM (vectors)) == image);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  if (push_undo)
+    gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_IMAGE_ITEM_REMOVE,
+                                 C_("undo-type", "Remove Path"));
+
+  gimp_item_start_move (GIMP_ITEM (vectors), push_undo);
+
+  active_vectors = gimp_image_get_active_vectors (image);
+
+  if (push_undo)
+    gimp_image_undo_push_vectors_remove (image, C_("undo-type", "Remove Path"), vectors,
+                                         gimp_vectors_get_parent (vectors),
+                                         gimp_item_get_index (GIMP_ITEM (vectors)),
+                                         active_vectors);
+
+  g_object_ref (vectors);
+
+  new_active =
+    GIMP_VECTORS (gimp_item_tree_remove_item (private->vectors,
+                                              GIMP_ITEM (vectors),
+                                              GIMP_ITEM (new_active)));
+
+  if (active_vectors &&
+      (vectors == active_vectors ||
+       gimp_viewable_is_ancestor (GIMP_VIEWABLE (vectors),
+                                  GIMP_VIEWABLE (active_vectors))))
+    {
+      gimp_image_set_active_vectors (image, new_active);
+    }
+
+  gimp_item_end_move (GIMP_ITEM (vectors), push_undo);
+
+  g_object_unref (vectors);
+
+  if (push_undo)
+    gimp_image_undo_group_end (image);
+}
+
+gboolean
+gimp_image_coords_in_active_pickable (GimpImage        *image,
+                                      const GimpCoords *coords,
+                                      gboolean          show_all,
+                                      gboolean          sample_merged,
+                                      gboolean          selected_only)
+{
+  gint     x, y;
+  gboolean in_pickable = FALSE;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+
+  x = floor (coords->x);
+  y = floor (coords->y);
+
+  if (sample_merged)
+    {
+      if (show_all || (x >= 0 && x < gimp_image_get_width  (image) &&
+                       y >= 0 && y < gimp_image_get_height (image)))
+        {
+          in_pickable = TRUE;
+        }
+    }
+  else
+    {
+      GimpDrawable *drawable = gimp_image_get_active_drawable (image);
+
+      if (drawable)
+        {
+          GimpItem *item = GIMP_ITEM (drawable);
+          gint      off_x, off_y;
+          gint      d_x, d_y;
+
+          gimp_item_get_offset (item, &off_x, &off_y);
+
+          d_x = x - off_x;
+          d_y = y - off_y;
+
+          if (d_x >= 0 && d_x < gimp_item_get_width  (item) &&
+              d_y >= 0 && d_y < gimp_item_get_height (item))
+            in_pickable = TRUE;
+        }
+    }
+
+  if (in_pickable && selected_only)
+    {
+      GimpChannel *selection = gimp_image_get_mask (image);
+
+      if (! gimp_channel_is_empty (selection) &&
+          ! gimp_pickable_get_opacity_at (GIMP_PICKABLE (selection),
+                                          x, y))
+        {
+          in_pickable = FALSE;
+        }
+    }
+
+  return in_pickable;
+}
+
+void
+gimp_image_invalidate_previews (GimpImage *image)
+{
+  GimpItemStack *layers;
+  GimpItemStack *channels;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  layers   = GIMP_ITEM_STACK (gimp_image_get_layers (image));
+  channels = GIMP_ITEM_STACK (gimp_image_get_channels (image));
+
+  gimp_item_stack_invalidate_previews (layers);
+  gimp_item_stack_invalidate_previews (channels);
+}
+
+/* Sets the image into a "converting" state, which is there to warn other code
+ * (such as shell render code) that the image properties might be in an
+ * inconsistent state. For instance when converting to another precision with
+ * gimp_image_convert_precision(), the babl format may be updated first, and the
+ * profile later, after all drawables are converted. Rendering the image
+ * in-between would at best render broken previews (at worst, crash, e.g.
+ * because we depend on allocated data which might have become too small).
+ */
+void
+gimp_image_set_converting (GimpImage *image,
+                           gboolean   converting)
+{
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  g_object_set (image,
+                "converting", converting,
+                NULL);
+}
+
+gboolean
+gimp_image_get_converting (GimpImage *image)
+{
+  GimpImagePrivate *private;
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  return private->converting;
+}
diff --git a/app/core/gimpimage.h b/app/core/gimpimage.h
new file mode 100644
index 0000000..50654ab
--- /dev/null
+++ b/app/core/gimpimage.h
@@ -0,0 +1,463 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattisbvf
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_IMAGE_H__
+#define __GIMP_IMAGE_H__
+
+
+#include "gimpviewable.h"
+
+
+#define GIMP_IMAGE_ACTIVE_PARENT ((gpointer) 1)
+
+
+#define GIMP_TYPE_IMAGE            (gimp_image_get_type ())
+#define GIMP_IMAGE(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_IMAGE, GimpImage))
+#define GIMP_IMAGE_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_IMAGE, GimpImageClass))
+#define GIMP_IS_IMAGE(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_IMAGE))
+#define GIMP_IS_IMAGE_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_IMAGE))
+#define GIMP_IMAGE_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_IMAGE, GimpImageClass))
+
+
+typedef struct _GimpImageClass   GimpImageClass;
+typedef struct _GimpImagePrivate GimpImagePrivate;
+
+struct _GimpImage
+{
+  GimpViewable      parent_instance;
+
+  Gimp             *gimp;  /*  the GIMP the image belongs to  */
+
+  GimpImagePrivate *priv;
+};
+
+struct _GimpImageClass
+{
+  GimpViewableClass  parent_class;
+
+  /*  signals  */
+  void (* mode_changed)                 (GimpImage            *image);
+  void (* precision_changed)            (GimpImage            *image);
+  void (* alpha_changed)                (GimpImage            *image);
+  void (* floating_selection_changed)   (GimpImage            *image);
+  void (* active_layer_changed)         (GimpImage            *image);
+  void (* active_channel_changed)       (GimpImage            *image);
+  void (* active_vectors_changed)       (GimpImage            *image);
+  void (* linked_items_changed)         (GimpImage            *image);
+  void (* component_visibility_changed) (GimpImage            *image,
+                                         GimpChannelType       channel);
+  void (* component_active_changed)     (GimpImage            *image,
+                                         GimpChannelType       channel);
+  void (* mask_changed)                 (GimpImage            *image);
+  void (* resolution_changed)           (GimpImage            *image);
+  void (* size_changed_detailed)        (GimpImage            *image,
+                                         gint                  previous_origin_x,
+                                         gint                  previous_origin_y,
+                                         gint                  previous_width,
+                                         gint                  previous_height);
+  void (* unit_changed)                 (GimpImage            *image);
+  void (* quick_mask_changed)           (GimpImage            *image);
+  void (* selection_invalidate)         (GimpImage            *image);
+
+  void (* clean)                        (GimpImage            *image,
+                                         GimpDirtyMask         dirty_mask);
+  void (* dirty)                        (GimpImage            *image,
+                                         GimpDirtyMask         dirty_mask);
+  void (* saving)                       (GimpImage            *image);
+  void (* saved)                        (GimpImage            *image,
+                                         GFile                *file);
+  void (* exported)                     (GimpImage            *image,
+                                         GFile                *file);
+
+  void (* guide_added)                  (GimpImage            *image,
+                                         GimpGuide            *guide);
+  void (* guide_removed)                (GimpImage            *image,
+                                         GimpGuide            *guide);
+  void (* guide_moved)                  (GimpImage            *image,
+                                         GimpGuide            *guide);
+  void (* sample_point_added)           (GimpImage            *image,
+                                         GimpSamplePoint      *sample_point);
+  void (* sample_point_removed)         (GimpImage            *image,
+                                         GimpSamplePoint      *sample_point);
+  void (* sample_point_moved)           (GimpImage            *image,
+                                         GimpSamplePoint      *sample_point);
+  void (* parasite_attached)            (GimpImage            *image,
+                                         const gchar          *name);
+  void (* parasite_detached)            (GimpImage            *image,
+                                         const gchar          *name);
+  void (* colormap_changed)             (GimpImage            *image,
+                                         gint                  color_index);
+  void (* undo_event)                   (GimpImage            *image,
+                                         GimpUndoEvent         event,
+                                         GimpUndo             *undo);
+};
+
+
+GType           gimp_image_get_type              (void) G_GNUC_CONST;
+
+GimpImage     * gimp_image_new                   (Gimp               *gimp,
+                                                  gint                width,
+                                                  gint                height,
+                                                  GimpImageBaseType   base_type,
+                                                  GimpPrecision       precision);
+
+gint64          gimp_image_estimate_memsize      (GimpImage          *image,
+                                                  GimpComponentType   component_type,
+                                                  gint                width,
+                                                  gint                height);
+
+GimpImageBaseType  gimp_image_get_base_type      (GimpImage          *image);
+GimpComponentType  gimp_image_get_component_type (GimpImage          *image);
+GimpPrecision      gimp_image_get_precision      (GimpImage          *image);
+
+const Babl    * gimp_image_get_format            (GimpImage          *image,
+                                                  GimpImageBaseType   base_type,
+                                                  GimpPrecision       precision,
+                                                  gboolean            with_alpha);
+const Babl    * gimp_image_get_layer_format      (GimpImage          *image,
+                                                  gboolean            with_alpha);
+const Babl    * gimp_image_get_channel_format    (GimpImage          *image);
+const Babl    * gimp_image_get_mask_format       (GimpImage          *image);
+
+GimpLayerMode   gimp_image_get_default_new_layer_mode
+                                                 (GimpImage          *image);
+void            gimp_image_unset_default_new_layer_mode
+                                                 (GimpImage          *image);
+
+gint            gimp_image_get_ID                (GimpImage          *image);
+GimpImage     * gimp_image_get_by_ID             (Gimp               *gimp,
+                                                  gint                id);
+
+GFile         * gimp_image_get_file              (GimpImage          *image);
+GFile         * gimp_image_get_untitled_file     (GimpImage          *image);
+GFile         * gimp_image_get_file_or_untitled  (GimpImage          *image);
+GFile         * gimp_image_get_imported_file     (GimpImage          *image);
+GFile         * gimp_image_get_exported_file     (GimpImage          *image);
+GFile         * gimp_image_get_save_a_copy_file  (GimpImage          *image);
+GFile         * gimp_image_get_any_file          (GimpImage          *image);
+
+void            gimp_image_set_file              (GimpImage          *image,
+                                                  GFile              *file);
+void            gimp_image_set_imported_file     (GimpImage          *image,
+                                                  GFile              *file);
+void            gimp_image_set_exported_file     (GimpImage          *image,
+                                                  GFile              *file);
+void            gimp_image_set_save_a_copy_file  (GimpImage          *image,
+                                                  GFile              *file);
+
+const gchar   * gimp_image_get_display_name      (GimpImage          *image);
+const gchar   * gimp_image_get_display_path      (GimpImage          *image);
+
+void            gimp_image_set_load_proc         (GimpImage          *image,
+                                                  GimpPlugInProcedure *proc);
+GimpPlugInProcedure * gimp_image_get_load_proc   (GimpImage          *image);
+void            gimp_image_set_save_proc         (GimpImage          *image,
+                                                  GimpPlugInProcedure *proc);
+GimpPlugInProcedure * gimp_image_get_save_proc   (GimpImage          *image);
+void            gimp_image_saving                (GimpImage          *image);
+void            gimp_image_saved                 (GimpImage          *image,
+                                                  GFile              *file);
+void            gimp_image_set_export_proc       (GimpImage          *image,
+                                                  GimpPlugInProcedure *proc);
+GimpPlugInProcedure * gimp_image_get_export_proc (GimpImage          *image);
+void            gimp_image_exported              (GimpImage          *image,
+                                                  GFile              *file);
+
+gint            gimp_image_get_xcf_version       (GimpImage          *image,
+                                                  gboolean            zlib_compression,
+                                                  gint               *gimp_version,
+                                                  const gchar       **version_string,
+                                                  gchar             **version_reason);
+
+void            gimp_image_set_xcf_compression   (GimpImage          *image,
+                                                  gboolean            compression);
+gboolean        gimp_image_get_xcf_compression   (GimpImage          *image);
+
+void            gimp_image_set_resolution        (GimpImage          *image,
+                                                  gdouble             xres,
+                                                  gdouble             yres);
+void            gimp_image_get_resolution        (GimpImage          *image,
+                                                  gdouble            *xres,
+                                                  gdouble            *yres);
+void            gimp_image_resolution_changed    (GimpImage          *image);
+
+void            gimp_image_set_unit              (GimpImage          *image,
+                                                  GimpUnit            unit);
+GimpUnit        gimp_image_get_unit              (GimpImage          *image);
+void            gimp_image_unit_changed          (GimpImage          *image);
+
+gint            gimp_image_get_width             (GimpImage          *image);
+gint            gimp_image_get_height            (GimpImage          *image);
+
+gboolean        gimp_image_has_alpha             (GimpImage          *image);
+gboolean        gimp_image_is_empty              (GimpImage          *image);
+
+void           gimp_image_set_floating_selection (GimpImage          *image,
+                                                  GimpLayer          *floating_sel);
+GimpLayer    * gimp_image_get_floating_selection (GimpImage          *image);
+void       gimp_image_floating_selection_changed (GimpImage          *image);
+
+GimpChannel   * gimp_image_get_mask              (GimpImage          *image);
+void            gimp_image_mask_changed          (GimpImage          *image);
+
+
+/*  image components  */
+
+const Babl    * gimp_image_get_component_format  (GimpImage          *image,
+                                                  GimpChannelType     channel);
+gint            gimp_image_get_component_index   (GimpImage          *image,
+                                                  GimpChannelType     channel);
+
+void            gimp_image_set_component_active  (GimpImage          *image,
+                                                  GimpChannelType     type,
+                                                  gboolean            active);
+gboolean        gimp_image_get_component_active  (GimpImage          *image,
+                                                  GimpChannelType     type);
+void            gimp_image_get_active_array      (GimpImage          *image,
+                                                  gboolean           *components);
+GimpComponentMask gimp_image_get_active_mask     (GimpImage          *image);
+
+void            gimp_image_set_component_visible (GimpImage          *image,
+                                                  GimpChannelType     type,
+                                                  gboolean            visible);
+gboolean        gimp_image_get_component_visible (GimpImage          *image,
+                                                  GimpChannelType     type);
+void            gimp_image_get_visible_array     (GimpImage          *image,
+                                                  gboolean           *components);
+GimpComponentMask gimp_image_get_visible_mask    (GimpImage          *image);
+
+
+/*  emitting image signals  */
+
+void            gimp_image_mode_changed          (GimpImage          *image);
+void            gimp_image_precision_changed     (GimpImage          *image);
+void            gimp_image_alpha_changed         (GimpImage          *image);
+void            gimp_image_linked_items_changed  (GimpImage          *image);
+void            gimp_image_invalidate            (GimpImage          *image,
+                                                  gint                x,
+                                                  gint                y,
+                                                  gint                width,
+                                                  gint                height);
+void            gimp_image_invalidate_all        (GimpImage          *image);
+void            gimp_image_guide_added           (GimpImage          *image,
+                                                  GimpGuide          *guide);
+void            gimp_image_guide_removed         (GimpImage          *image,
+                                                  GimpGuide          *guide);
+void            gimp_image_guide_moved           (GimpImage          *image,
+                                                  GimpGuide          *guide);
+
+void            gimp_image_sample_point_added    (GimpImage          *image,
+                                                  GimpSamplePoint    *sample_point);
+void            gimp_image_sample_point_removed  (GimpImage          *image,
+                                                  GimpSamplePoint    *sample_point);
+void            gimp_image_sample_point_moved    (GimpImage          *image,
+                                                  GimpSamplePoint    *sample_point);
+void            gimp_image_colormap_changed      (GimpImage          *image,
+                                                  gint                col);
+void            gimp_image_selection_invalidate  (GimpImage          *image);
+void            gimp_image_quick_mask_changed    (GimpImage          *image);
+void            gimp_image_size_changed_detailed (GimpImage          *image,
+                                                  gint                previous_origin_x,
+                                                  gint                previous_origin_y,
+                                                  gint                previous_width,
+                                                  gint                previous_height);
+void            gimp_image_undo_event            (GimpImage          *image,
+                                                  GimpUndoEvent       event,
+                                                  GimpUndo           *undo);
+
+
+/*  dirty counters  */
+
+gint            gimp_image_dirty                 (GimpImage          *image,
+                                                  GimpDirtyMask       dirty_mask);
+gint            gimp_image_clean                 (GimpImage          *image,
+                                                  GimpDirtyMask       dirty_mask);
+void            gimp_image_clean_all             (GimpImage          *image);
+void            gimp_image_export_clean_all      (GimpImage          *image);
+gint            gimp_image_is_dirty              (GimpImage          *image);
+gboolean        gimp_image_is_export_dirty       (GimpImage          *image);
+gint64          gimp_image_get_dirty_time        (GimpImage          *image);
+
+
+/*  flush this image's displays  */
+
+void            gimp_image_flush                 (GimpImage          *image);
+
+
+/*  display / instance counters  */
+
+gint            gimp_image_get_display_count     (GimpImage          *image);
+void            gimp_image_inc_display_count     (GimpImage          *image);
+void            gimp_image_dec_display_count     (GimpImage          *image);
+
+gint            gimp_image_get_instance_count    (GimpImage          *image);
+void            gimp_image_inc_instance_count    (GimpImage          *image);
+
+void            gimp_image_inc_show_all_count    (GimpImage          *image);
+void            gimp_image_dec_show_all_count    (GimpImage          *image);
+
+
+/*  parasites  */
+
+const GimpParasite * gimp_image_parasite_find    (GimpImage          *image,
+                                                  const gchar        *name);
+gchar        ** gimp_image_parasite_list         (GimpImage          *image,
+                                                  gint               *count);
+gboolean        gimp_image_parasite_validate     (GimpImage          *image,
+                                                  const GimpParasite *parasite,
+                                                  GError            **error);
+void            gimp_image_parasite_attach       (GimpImage          *image,
+                                                  const GimpParasite *parasite,
+                                                  gboolean            push_undo);
+void            gimp_image_parasite_detach       (GimpImage          *image,
+                                                  const gchar        *name,
+                                                  gboolean            push_undo);
+
+
+/*  tattoos  */
+
+GimpTattoo      gimp_image_get_new_tattoo        (GimpImage          *image);
+gboolean        gimp_image_set_tattoo_state      (GimpImage          *image,
+                                                  GimpTattoo          val);
+GimpTattoo      gimp_image_get_tattoo_state      (GimpImage          *image);
+
+
+/*  projection  */
+
+GimpProjection * gimp_image_get_projection       (GimpImage          *image);
+
+
+/*  layers / channels / vectors  */
+
+GimpItemTree  * gimp_image_get_layer_tree        (GimpImage          *image);
+GimpItemTree  * gimp_image_get_channel_tree      (GimpImage          *image);
+GimpItemTree  * gimp_image_get_vectors_tree      (GimpImage          *image);
+
+GimpContainer * gimp_image_get_layers            (GimpImage          *image);
+GimpContainer * gimp_image_get_channels          (GimpImage          *image);
+GimpContainer * gimp_image_get_vectors           (GimpImage          *image);
+
+gint            gimp_image_get_n_layers          (GimpImage          *image);
+gint            gimp_image_get_n_channels        (GimpImage          *image);
+gint            gimp_image_get_n_vectors         (GimpImage          *image);
+
+GList         * gimp_image_get_layer_iter        (GimpImage          *image);
+GList         * gimp_image_get_channel_iter      (GimpImage          *image);
+GList         * gimp_image_get_vectors_iter      (GimpImage          *image);
+
+GList         * gimp_image_get_layer_list        (GimpImage          *image);
+GList         * gimp_image_get_channel_list      (GimpImage          *image);
+GList         * gimp_image_get_vectors_list      (GimpImage          *image);
+
+GimpDrawable  * gimp_image_get_active_drawable   (GimpImage          *image);
+GimpLayer     * gimp_image_get_active_layer      (GimpImage          *image);
+GimpChannel   * gimp_image_get_active_channel    (GimpImage          *image);
+GimpVectors   * gimp_image_get_active_vectors    (GimpImage          *image);
+
+GimpLayer     * gimp_image_set_active_layer      (GimpImage          *image,
+                                                  GimpLayer          *layer);
+GimpChannel   * gimp_image_set_active_channel    (GimpImage          *image,
+                                                  GimpChannel        *channel);
+GimpChannel   * gimp_image_unset_active_channel  (GimpImage          *image);
+GimpVectors   * gimp_image_set_active_vectors    (GimpImage          *image,
+                                                  GimpVectors        *vectors);
+
+GimpLayer     * gimp_image_get_layer_by_tattoo   (GimpImage          *image,
+                                                  GimpTattoo          tattoo);
+GimpChannel   * gimp_image_get_channel_by_tattoo (GimpImage          *image,
+                                                  GimpTattoo          tattoo);
+GimpVectors   * gimp_image_get_vectors_by_tattoo (GimpImage          *image,
+                                                  GimpTattoo          tattoo);
+
+GimpLayer     * gimp_image_get_layer_by_name     (GimpImage          *image,
+                                                  const gchar        *name);
+GimpChannel   * gimp_image_get_channel_by_name   (GimpImage          *image,
+                                                  const gchar        *name);
+GimpVectors   * gimp_image_get_vectors_by_name   (GimpImage          *image,
+                                                  const gchar        *name);
+
+gboolean        gimp_image_reorder_item          (GimpImage          *image,
+                                                  GimpItem           *item,
+                                                  GimpItem           *new_parent,
+                                                  gint                new_index,
+                                                  gboolean            push_undo,
+                                                  const gchar        *undo_desc);
+gboolean        gimp_image_raise_item            (GimpImage          *image,
+                                                  GimpItem           *item,
+                                                  GError            **error);
+gboolean        gimp_image_raise_item_to_top     (GimpImage          *image,
+                                                  GimpItem           *item);
+gboolean        gimp_image_lower_item            (GimpImage          *image,
+                                                  GimpItem           *item,
+                                                  GError            **error);
+gboolean        gimp_image_lower_item_to_bottom  (GimpImage          *image,
+                                                  GimpItem           *item);
+
+gboolean        gimp_image_add_layer             (GimpImage          *image,
+                                                  GimpLayer          *layer,
+                                                  GimpLayer          *parent,
+                                                  gint                position,
+                                                  gboolean            push_undo);
+void            gimp_image_remove_layer          (GimpImage          *image,
+                                                  GimpLayer          *layer,
+                                                  gboolean            push_undo,
+                                                  GimpLayer          *new_active);
+
+void            gimp_image_add_layers            (GimpImage          *image,
+                                                  GList              *layers,
+                                                  GimpLayer          *parent,
+                                                  gint                position,
+                                                  gint                x,
+                                                  gint                y,
+                                                  gint                width,
+                                                  gint                height,
+                                                  const gchar        *undo_desc);
+
+gboolean        gimp_image_add_channel           (GimpImage          *image,
+                                                  GimpChannel        *channel,
+                                                  GimpChannel        *parent,
+                                                  gint                position,
+                                                  gboolean            push_undo);
+void            gimp_image_remove_channel        (GimpImage          *image,
+                                                  GimpChannel        *channel,
+                                                  gboolean            push_undo,
+                                                  GimpChannel        *new_active);
+
+gboolean        gimp_image_add_vectors           (GimpImage          *image,
+                                                  GimpVectors        *vectors,
+                                                  GimpVectors        *parent,
+                                                  gint                position,
+                                                  gboolean            push_undo);
+void            gimp_image_remove_vectors        (GimpImage          *image,
+                                                  GimpVectors        *vectors,
+                                                  gboolean            push_undo,
+                                                  GimpVectors        *new_active);
+
+gboolean    gimp_image_coords_in_active_pickable (GimpImage          *image,
+                                                  const GimpCoords   *coords,
+                                                  gboolean            show_all,
+                                                  gboolean            sample_merged,
+                                                  gboolean            selected_only);
+
+void            gimp_image_invalidate_previews   (GimpImage          *image);
+
+void            gimp_image_set_converting        (GimpImage          *image,
+                                                  gboolean            converting);
+gboolean        gimp_image_get_converting        (GimpImage          *image);
+
+
+#endif /* __GIMP_IMAGE_H__ */
diff --git a/app/core/gimpimagefile.c b/app/core/gimpimagefile.c
new file mode 100644
index 0000000..cf079d8
--- /dev/null
+++ b/app/core/gimpimagefile.c
@@ -0,0 +1,1078 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpimagefile.c
+ *
+ * Copyright (C) 2001-2004  Sven Neumann <sven@gimp.org>
+ *                          Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <gegl.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpthumb/gimpthumb.h"
+
+#include "core-types.h"
+
+#include "config/gimpcoreconfig.h"
+
+#include "gegl/gimp-babl.h"
+#include "gegl/gimp-gegl-utils.h"
+
+#include "gimp.h"
+#include "gimpcontainer.h"
+#include "gimpcontext.h"
+#include "gimpimage.h"
+#include "gimpimagefile.h"
+#include "gimpmarshal.h"
+#include "gimppickable.h"
+#include "gimpprogress.h"
+
+#include "file/file-open.h"
+
+#include "gimp-intl.h"
+
+
+enum
+{
+  INFO_CHANGED,
+  LAST_SIGNAL
+};
+
+
+typedef struct _GimpImagefilePrivate GimpImagefilePrivate;
+
+struct _GimpImagefilePrivate
+{
+  Gimp          *gimp;
+
+  GFile         *file;
+  GimpThumbnail *thumbnail;
+  GIcon         *icon;
+  GCancellable  *icon_cancellable;
+
+  gchar         *description;
+  gboolean       static_desc;
+};
+
+#define GET_PRIVATE(imagefile) ((GimpImagefilePrivate *) gimp_imagefile_get_instance_private ((GimpImagefile *) (imagefile)))
+
+
+static void        gimp_imagefile_dispose          (GObject        *object);
+static void        gimp_imagefile_finalize         (GObject        *object);
+
+static void        gimp_imagefile_name_changed     (GimpObject     *object);
+
+static GdkPixbuf * gimp_imagefile_get_new_pixbuf   (GimpViewable   *viewable,
+                                                    GimpContext    *context,
+                                                    gint            width,
+                                                    gint            height);
+static gchar     * gimp_imagefile_get_description  (GimpViewable   *viewable,
+                                                    gchar         **tooltip);
+
+static void        gimp_imagefile_info_changed     (GimpImagefile  *imagefile);
+static void        gimp_imagefile_notify_thumbnail (GimpImagefile  *imagefile,
+                                                    GParamSpec     *pspec);
+
+static void        gimp_imagefile_icon_callback    (GObject        *source_object,
+                                                    GAsyncResult   *result,
+                                                    gpointer        data);
+
+static GdkPixbuf * gimp_imagefile_load_thumb       (GimpImagefile  *imagefile,
+                                                    gint            width,
+                                                    gint            height);
+static gboolean    gimp_imagefile_save_thumb       (GimpImagefile  *imagefile,
+                                                    GimpImage      *image,
+                                                    gint            size,
+                                                    gboolean        replace,
+                                                    GError        **error);
+
+static void     gimp_thumbnail_set_info_from_image (GimpThumbnail  *thumbnail,
+                                                    const gchar    *mime_type,
+                                                    GimpImage      *image);
+static void     gimp_thumbnail_set_info            (GimpThumbnail  *thumbnail,
+                                                    const gchar    *mime_type,
+                                                    gint            width,
+                                                    gint            height,
+                                                    const Babl     *format,
+                                                    gint            num_layers);
+
+
+G_DEFINE_TYPE_WITH_PRIVATE (GimpImagefile, gimp_imagefile, GIMP_TYPE_VIEWABLE)
+
+#define parent_class gimp_imagefile_parent_class
+
+static guint gimp_imagefile_signals[LAST_SIGNAL] = { 0 };
+
+
+static void
+gimp_imagefile_class_init (GimpImagefileClass *klass)
+{
+  GObjectClass      *object_class      = G_OBJECT_CLASS (klass);
+  GimpObjectClass   *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+  GimpViewableClass *viewable_class    = GIMP_VIEWABLE_CLASS (klass);
+  gchar             *creator;
+
+  gimp_imagefile_signals[INFO_CHANGED] =
+    g_signal_new ("info-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpImagefileClass, info_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  object_class->dispose               = gimp_imagefile_dispose;
+  object_class->finalize              = gimp_imagefile_finalize;
+
+  gimp_object_class->name_changed     = gimp_imagefile_name_changed;
+
+  viewable_class->name_changed_signal = "info-changed";
+  viewable_class->get_new_pixbuf      = gimp_imagefile_get_new_pixbuf;
+  viewable_class->get_description     = gimp_imagefile_get_description;
+
+  g_type_class_ref (GIMP_TYPE_IMAGE_TYPE);
+
+  creator = g_strdup_printf ("gimp-%d.%d",
+                             GIMP_MAJOR_VERSION, GIMP_MINOR_VERSION);
+
+  gimp_thumb_init (creator, NULL);
+
+  g_free (creator);
+}
+
+static void
+gimp_imagefile_init (GimpImagefile *imagefile)
+{
+  GimpImagefilePrivate *private = GET_PRIVATE (imagefile);
+
+  private->thumbnail = gimp_thumbnail_new ();
+
+  g_signal_connect_object (private->thumbnail, "notify",
+                           G_CALLBACK (gimp_imagefile_notify_thumbnail),
+                           imagefile, G_CONNECT_SWAPPED);
+}
+
+static void
+gimp_imagefile_dispose (GObject *object)
+{
+  GimpImagefilePrivate *private = GET_PRIVATE (object);
+
+  if (private->icon_cancellable)
+    {
+      g_cancellable_cancel (private->icon_cancellable);
+      g_clear_object (&private->icon_cancellable);
+    }
+
+  G_OBJECT_CLASS (parent_class)->dispose (object);
+}
+
+static void
+gimp_imagefile_finalize (GObject *object)
+{
+  GimpImagefilePrivate *private = GET_PRIVATE (object);
+
+  if (private->description)
+    {
+      if (! private->static_desc)
+        g_free (private->description);
+
+      private->description = NULL;
+    }
+
+  g_clear_object (&private->thumbnail);
+  g_clear_object (&private->icon);
+  g_clear_object (&private->file);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gimp_imagefile_name_changed (GimpObject *object)
+{
+  GimpImagefilePrivate *private = GET_PRIVATE (object);
+
+  if (GIMP_OBJECT_CLASS (parent_class)->name_changed)
+    GIMP_OBJECT_CLASS (parent_class)->name_changed (object);
+
+  gimp_thumbnail_set_uri (private->thumbnail, gimp_object_get_name (object));
+
+  g_clear_object (&private->file);
+
+  if (gimp_object_get_name (object))
+    private->file = g_file_new_for_uri (gimp_object_get_name (object));
+}
+
+static GdkPixbuf *
+gimp_imagefile_get_new_pixbuf (GimpViewable *viewable,
+                               GimpContext  *context,
+                               gint          width,
+                               gint          height)
+{
+  GimpImagefile *imagefile = GIMP_IMAGEFILE (viewable);
+
+  if (! gimp_object_get_name (imagefile))
+    return NULL;
+
+  return gimp_imagefile_load_thumb (imagefile, width, height);
+}
+
+static gchar *
+gimp_imagefile_get_description (GimpViewable   *viewable,
+                                gchar         **tooltip)
+{
+  GimpImagefile        *imagefile = GIMP_IMAGEFILE (viewable);
+  GimpImagefilePrivate *private   = GET_PRIVATE (imagefile);
+  GimpThumbnail        *thumbnail = private->thumbnail;
+  gchar                *basename;
+
+  if (! private->file)
+    return NULL;
+
+  if (tooltip)
+    {
+      const gchar *name;
+      const gchar *desc;
+
+      name = gimp_file_get_utf8_name (private->file);
+      desc = gimp_imagefile_get_desc_string (imagefile);
+
+      if (desc)
+        *tooltip = g_strdup_printf ("%s\n%s", name, desc);
+      else
+        *tooltip = g_strdup (name);
+    }
+
+  basename = g_path_get_basename (gimp_file_get_utf8_name (private->file));
+
+  if (thumbnail->image_width > 0 && thumbnail->image_height > 0)
+    {
+      gchar *tmp = basename;
+
+      basename = g_strdup_printf ("%s (%d × %d)",
+                                  tmp,
+                                  thumbnail->image_width,
+                                  thumbnail->image_height);
+      g_free (tmp);
+    }
+
+  return basename;
+}
+
+
+/*  public functions  */
+
+GimpImagefile *
+gimp_imagefile_new (Gimp  *gimp,
+                    GFile *file)
+{
+  GimpImagefile *imagefile;
+
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+  g_return_val_if_fail (file == NULL || G_IS_FILE (file), NULL);
+
+  imagefile = g_object_new (GIMP_TYPE_IMAGEFILE, NULL);
+
+  GET_PRIVATE (imagefile)->gimp = gimp;
+
+  if (file)
+    {
+      gimp_object_take_name (GIMP_OBJECT (imagefile), g_file_get_uri (file));
+
+      /* file member gets created by gimp_imagefile_name_changed() */
+    }
+
+  return imagefile;
+}
+
+GFile *
+gimp_imagefile_get_file (GimpImagefile *imagefile)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGEFILE (imagefile), NULL);
+
+  return GET_PRIVATE (imagefile)->file;
+}
+
+void
+gimp_imagefile_set_file (GimpImagefile *imagefile,
+                         GFile         *file)
+{
+  g_return_if_fail (GIMP_IS_IMAGEFILE (imagefile));
+  g_return_if_fail (file == NULL || G_IS_FILE (file));
+
+  if (GET_PRIVATE (imagefile)->file != file)
+    {
+      gimp_object_take_name (GIMP_OBJECT (imagefile),
+                             file ? g_file_get_uri (file) : NULL);
+    }
+}
+
+GimpThumbnail *
+gimp_imagefile_get_thumbnail (GimpImagefile *imagefile)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGEFILE (imagefile), NULL);
+
+  return GET_PRIVATE (imagefile)->thumbnail;
+}
+
+GIcon *
+gimp_imagefile_get_gicon (GimpImagefile *imagefile)
+{
+  GimpImagefilePrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_IMAGEFILE (imagefile), NULL);
+
+  private = GET_PRIVATE (imagefile);
+
+  if (private->icon)
+    return private->icon;
+
+  if (private->file && ! private->icon_cancellable)
+    {
+      private->icon_cancellable = g_cancellable_new ();
+
+      g_file_query_info_async (private->file, "standard::icon",
+                               G_FILE_QUERY_INFO_NONE,
+                               G_PRIORITY_DEFAULT,
+                               private->icon_cancellable,
+                               gimp_imagefile_icon_callback,
+                               imagefile);
+    }
+
+  return NULL;
+}
+
+void
+gimp_imagefile_set_mime_type (GimpImagefile *imagefile,
+                              const gchar   *mime_type)
+{
+  g_return_if_fail (GIMP_IS_IMAGEFILE (imagefile));
+
+  g_object_set (GET_PRIVATE (imagefile)->thumbnail,
+                "image-mimetype", mime_type,
+                NULL);
+}
+
+void
+gimp_imagefile_update (GimpImagefile *imagefile)
+{
+  GimpImagefilePrivate *private;
+  gchar                *uri;
+
+  g_return_if_fail (GIMP_IS_IMAGEFILE (imagefile));
+
+  private = GET_PRIVATE (imagefile);
+
+  gimp_viewable_invalidate_preview (GIMP_VIEWABLE (imagefile));
+
+  g_object_get (private->thumbnail,
+                "image-uri", &uri,
+                NULL);
+
+  if (uri)
+    {
+      GimpImagefile *documents_imagefile = (GimpImagefile *)
+        gimp_container_get_child_by_name (private->gimp->documents, uri);
+
+      if (documents_imagefile != imagefile &&
+          GIMP_IS_IMAGEFILE (documents_imagefile))
+        gimp_viewable_invalidate_preview (GIMP_VIEWABLE (documents_imagefile));
+
+      g_free (uri);
+    }
+}
+
+gboolean
+gimp_imagefile_create_thumbnail (GimpImagefile  *imagefile,
+                                 GimpContext    *context,
+                                 GimpProgress   *progress,
+                                 gint            size,
+                                 gboolean        replace,
+                                 GError        **error)
+{
+  GimpImagefilePrivate *private;
+  GimpThumbnail        *thumbnail;
+  GimpThumbState        image_state;
+
+  g_return_val_if_fail (GIMP_IS_IMAGEFILE (imagefile), FALSE);
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), FALSE);
+  g_return_val_if_fail (progress == NULL || GIMP_IS_PROGRESS (progress), FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  /* thumbnailing is disabled, we successfully did nothing */
+  if (size < 1)
+    return TRUE;
+
+  private = GET_PRIVATE (imagefile);
+
+  thumbnail = private->thumbnail;
+
+  gimp_thumbnail_set_uri (thumbnail,
+                          gimp_object_get_name (imagefile));
+
+  image_state = gimp_thumbnail_peek_image (thumbnail);
+
+  if (image_state == GIMP_THUMB_STATE_REMOTE ||
+      image_state >= GIMP_THUMB_STATE_EXISTS)
+    {
+      GimpImage     *image;
+      gboolean       success;
+      gint           width      = 0;
+      gint           height     = 0;
+      const gchar   *mime_type  = NULL;
+      const Babl    *format     = NULL;
+      gint           num_layers = -1;
+
+      /*  we only want to attempt thumbnailing on readable, regular files  */
+      if (g_file_is_native (private->file))
+        {
+          GFileInfo *file_info;
+          gboolean   regular;
+          gboolean   readable;
+
+          file_info = g_file_query_info (private->file,
+                                         G_FILE_ATTRIBUTE_STANDARD_TYPE ","
+                                         G_FILE_ATTRIBUTE_ACCESS_CAN_READ,
+                                         G_FILE_QUERY_INFO_NONE,
+                                         NULL, NULL);
+
+          regular  = (g_file_info_get_file_type (file_info) == G_FILE_TYPE_REGULAR);
+          readable = g_file_info_get_attribute_boolean (file_info,
+                                                        G_FILE_ATTRIBUTE_ACCESS_CAN_READ);
+
+          g_object_unref (file_info);
+
+          if (! (regular && readable))
+            return TRUE;
+        }
+
+      g_object_ref (imagefile);
+
+      /* don't pass the error, we're only interested in errors from
+       * actual thumbnail saving
+       */
+      image = file_open_thumbnail (private->gimp, context, progress,
+                                   private->file, size,
+                                   &mime_type, &width, &height,
+                                   &format, &num_layers, NULL);
+
+      if (image)
+        {
+          gimp_thumbnail_set_info (private->thumbnail,
+                                   mime_type, width, height,
+                                   format, num_layers);
+        }
+      else
+        {
+          GimpPDBStatusType  status;
+
+          /* don't pass the error, we're only interested in errors
+           * from actual thumbnail saving
+           */
+          image = file_open_image (private->gimp, context, progress,
+                                   private->file,
+                                   private->file,
+                                   FALSE, NULL, GIMP_RUN_NONINTERACTIVE,
+                                   &status, &mime_type, NULL);
+
+          if (image)
+            gimp_thumbnail_set_info_from_image (private->thumbnail,
+                                                mime_type, image);
+        }
+
+      if (image)
+        {
+          success = gimp_imagefile_save_thumb (imagefile,
+                                               image, size, replace,
+                                               error);
+
+          g_object_unref (image);
+        }
+      else
+        {
+          success = gimp_thumbnail_save_failure (thumbnail,
+                                                 "GIMP " GIMP_VERSION,
+                                                 error);
+          gimp_imagefile_update (imagefile);
+        }
+
+      g_object_unref (imagefile);
+
+      if (! success)
+        {
+          g_object_set (thumbnail,
+                        "thumb-state", GIMP_THUMB_STATE_FAILED,
+                        NULL);
+        }
+
+      return success;
+    }
+
+  return TRUE;
+}
+
+/*  The weak version doesn't ref the imagefile but deals gracefully
+ *  with an imagefile that is destroyed while the thumbnail is
+ *  created. This allows one to use this function w/o the need to
+ *  block the user interface.
+ */
+void
+gimp_imagefile_create_thumbnail_weak (GimpImagefile *imagefile,
+                                      GimpContext   *context,
+                                      GimpProgress  *progress,
+                                      gint           size,
+                                      gboolean       replace)
+{
+  GimpImagefilePrivate *private;
+  GimpImagefile        *local;
+
+  g_return_if_fail (GIMP_IS_IMAGEFILE (imagefile));
+
+  if (size < 1)
+    return;
+
+  private = GET_PRIVATE (imagefile);
+
+  if (! private->file)
+    return;
+
+  local = gimp_imagefile_new (private->gimp, private->file);
+
+  g_object_add_weak_pointer (G_OBJECT (imagefile), (gpointer) &imagefile);
+
+  if (! gimp_imagefile_create_thumbnail (local, context, progress, size, replace,
+                                         NULL))
+    {
+      /* The weak version works on a local copy so the thumbnail
+       * status of the actual image is not properly updated in case of
+       * creation failure, thus it would end up in a generic
+       * GIMP_THUMB_STATE_NOT_FOUND, which is less informative.
+       */
+      g_object_set (private->thumbnail,
+                    "thumb-state", GIMP_THUMB_STATE_FAILED,
+                    NULL);
+    }
+
+  if (imagefile)
+    {
+      GFile *file = gimp_imagefile_get_file (imagefile);
+
+      if (file && g_file_equal (file, gimp_imagefile_get_file (local)))
+        {
+          gimp_imagefile_update (imagefile);
+        }
+
+      g_object_remove_weak_pointer (G_OBJECT (imagefile),
+                                    (gpointer) &imagefile);
+    }
+
+  g_object_unref (local);
+}
+
+gboolean
+gimp_imagefile_check_thumbnail (GimpImagefile *imagefile)
+{
+  GimpImagefilePrivate *private;
+  gint                  size;
+
+  g_return_val_if_fail (GIMP_IS_IMAGEFILE (imagefile), FALSE);
+
+  private = GET_PRIVATE (imagefile);
+
+  size = private->gimp->config->thumbnail_size;
+
+  if (size > 0)
+    {
+      GimpThumbState  state;
+
+      state = gimp_thumbnail_check_thumb (private->thumbnail, size);
+
+      return (state == GIMP_THUMB_STATE_OK);
+    }
+
+  return TRUE;
+}
+
+gboolean
+gimp_imagefile_save_thumbnail (GimpImagefile  *imagefile,
+                               const gchar    *mime_type,
+                               GimpImage      *image,
+                               GError        **error)
+{
+  GimpImagefilePrivate *private;
+  gint                  size;
+  gboolean              success = TRUE;
+
+  g_return_val_if_fail (GIMP_IS_IMAGEFILE (imagefile), FALSE);
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  private = GET_PRIVATE (imagefile);
+
+  size = private->gimp->config->thumbnail_size;
+
+  if (size > 0)
+    {
+      gimp_thumbnail_set_info_from_image (private->thumbnail,
+                                          mime_type, image);
+
+      success = gimp_imagefile_save_thumb (imagefile,
+                                           image, size, FALSE,
+                                           error);
+    }
+
+  return success;
+}
+
+
+/*  private functions  */
+
+static void
+gimp_imagefile_info_changed (GimpImagefile *imagefile)
+{
+  GimpImagefilePrivate *private = GET_PRIVATE (imagefile);
+
+  if (private->description)
+    {
+      if (! private->static_desc)
+        g_free (private->description);
+
+      private->description = NULL;
+    }
+
+  g_clear_object (&private->icon);
+
+  g_signal_emit (imagefile, gimp_imagefile_signals[INFO_CHANGED], 0);
+}
+
+static void
+gimp_imagefile_notify_thumbnail (GimpImagefile *imagefile,
+                                 GParamSpec    *pspec)
+{
+  if (strcmp (pspec->name, "image-state") == 0 ||
+      strcmp (pspec->name, "thumb-state") == 0)
+    {
+      gimp_imagefile_info_changed (imagefile);
+    }
+}
+
+static void
+gimp_imagefile_icon_callback (GObject      *source_object,
+                              GAsyncResult *result,
+                              gpointer      data)
+{
+  GimpImagefile        *imagefile;
+  GimpImagefilePrivate *private;
+  GFile                *file  = G_FILE (source_object);
+  GError               *error = NULL;
+  GFileInfo            *file_info;
+
+  file_info = g_file_query_info_finish (file, result, &error);
+
+  if (error)
+    {
+      /* we were cancelled from dispose() and the imagefile is
+       * long gone, bail out
+       */
+      if (g_error_matches (error, G_IO_ERROR, G_IO_ERROR_CANCELLED))
+        {
+          g_clear_error (&error);
+          return;
+        }
+
+#ifdef GIMP_UNSTABLE
+      g_printerr ("%s: %s\n", G_STRFUNC, error->message);
+#endif
+
+      g_clear_error (&error);
+    }
+
+  imagefile = GIMP_IMAGEFILE (data);
+  private   = GET_PRIVATE (imagefile);
+
+  if (file_info)
+    {
+      private->icon = g_object_ref (g_file_info_get_icon (file_info));
+      g_object_unref (file_info);
+    }
+
+  g_clear_object (&private->icon_cancellable);
+
+  if (private->icon)
+    gimp_viewable_invalidate_preview (GIMP_VIEWABLE (imagefile));
+}
+
+const gchar *
+gimp_imagefile_get_desc_string (GimpImagefile *imagefile)
+{
+  GimpImagefilePrivate *private;
+  GimpThumbnail        *thumbnail;
+
+  g_return_val_if_fail (GIMP_IS_IMAGEFILE (imagefile), NULL);
+
+  private = GET_PRIVATE (imagefile);
+
+  if (private->description)
+    return (const gchar *) private->description;
+
+  thumbnail = private->thumbnail;
+
+  switch (thumbnail->image_state)
+    {
+    case GIMP_THUMB_STATE_UNKNOWN:
+      private->description = NULL;
+      private->static_desc = TRUE;
+      break;
+
+    case GIMP_THUMB_STATE_FOLDER:
+      private->description = (gchar *) _("Folder");
+      private->static_desc = TRUE;
+      break;
+
+    case GIMP_THUMB_STATE_SPECIAL:
+      private->description = (gchar *) _("Special File");
+      private->static_desc = TRUE;
+      break;
+
+    case GIMP_THUMB_STATE_NOT_FOUND:
+      private->description =
+        (gchar *) g_strerror (thumbnail->image_not_found_errno);
+      private->static_desc = TRUE;
+      break;
+
+    default:
+      {
+        GString *str = g_string_new (NULL);
+
+        if (thumbnail->image_state == GIMP_THUMB_STATE_REMOTE)
+          {
+            g_string_append (str, _("Remote File"));
+          }
+
+        if (thumbnail->image_filesize > 0)
+          {
+            gchar *size = g_format_size (thumbnail->image_filesize);
+
+            if (str->len > 0)
+              g_string_append_c (str, '\n');
+
+            g_string_append (str, size);
+            g_free (size);
+          }
+
+        switch (thumbnail->thumb_state)
+          {
+          case GIMP_THUMB_STATE_NOT_FOUND:
+            if (str->len > 0)
+              g_string_append_c (str, '\n');
+            g_string_append (str, _("Click to create preview"));
+            break;
+
+          case GIMP_THUMB_STATE_EXISTS:
+            if (str->len > 0)
+              g_string_append_c (str, '\n');
+            g_string_append (str, _("Loading preview..."));
+            break;
+
+          case GIMP_THUMB_STATE_OLD:
+            if (str->len > 0)
+              g_string_append_c (str, '\n');
+            g_string_append (str, _("Preview is out of date"));
+            break;
+
+          case GIMP_THUMB_STATE_FAILED:
+            if (str->len > 0)
+              g_string_append_c (str, '\n');
+            g_string_append (str, _("Cannot create preview"));
+            break;
+
+          case GIMP_THUMB_STATE_OK:
+            {
+              if (thumbnail->image_state == GIMP_THUMB_STATE_REMOTE)
+                {
+                  if (str->len > 0)
+                    g_string_append_c (str, '\n');
+
+                  g_string_append (str, _("(Preview may be out of date)"));
+                }
+
+              if (thumbnail->image_width > 0 && thumbnail->image_height > 0)
+                {
+                  if (str->len > 0)
+                    g_string_append_c (str, '\n');
+
+                  g_string_append_printf (str,
+                                          ngettext ("%d × %d pixel",
+                                                    "%d × %d pixels",
+                                                    thumbnail->image_height),
+                                          thumbnail->image_width,
+                                          thumbnail->image_height);
+                }
+
+              if (thumbnail->image_type)
+                {
+                  if (str->len > 0)
+                    g_string_append_c (str, '\n');
+
+                  g_string_append (str, gettext (thumbnail->image_type));
+                }
+
+              if (thumbnail->image_num_layers > 0)
+                {
+                  if (thumbnail->image_type)
+                    g_string_append_len (str, ", ", 2);
+                  else if (str->len > 0)
+                    g_string_append_c (str, '\n');
+
+                  g_string_append_printf (str,
+                                          ngettext ("%d layer",
+                                                    "%d layers",
+                                                    thumbnail->image_num_layers),
+                                          thumbnail->image_num_layers);
+                }
+            }
+            break;
+
+          default:
+            break;
+          }
+
+        private->description = g_string_free (str, FALSE);
+        private->static_desc = FALSE;
+      }
+    }
+
+  return (const gchar *) private->description;
+}
+
+static GdkPixbuf *
+gimp_imagefile_load_thumb (GimpImagefile *imagefile,
+                           gint           width,
+                           gint           height)
+{
+  GimpImagefilePrivate *private   = GET_PRIVATE (imagefile);
+  GimpThumbnail        *thumbnail = private->thumbnail;
+  GdkPixbuf            *pixbuf    = NULL;
+  GError               *error     = NULL;
+  gint                  size      = MAX (width, height);
+  gint                  pixbuf_width;
+  gint                  pixbuf_height;
+  gint                  preview_width;
+  gint                  preview_height;
+
+  if (gimp_thumbnail_peek_thumb (thumbnail, size) < GIMP_THUMB_STATE_EXISTS)
+    return NULL;
+
+  if (thumbnail->image_state == GIMP_THUMB_STATE_NOT_FOUND)
+    return NULL;
+
+  pixbuf = gimp_thumbnail_load_thumb (thumbnail, size, &error);
+
+  if (! pixbuf)
+    {
+      if (error)
+        {
+          gimp_message (private->gimp, NULL, GIMP_MESSAGE_ERROR,
+                        _("Could not open thumbnail '%s': %s"),
+                        thumbnail->thumb_filename, error->message);
+          g_clear_error (&error);
+        }
+
+      return NULL;
+    }
+
+  pixbuf_width  = gdk_pixbuf_get_width  (pixbuf);
+  pixbuf_height = gdk_pixbuf_get_height (pixbuf);
+
+  gimp_viewable_calc_preview_size (pixbuf_width,
+                                   pixbuf_height,
+                                   width,
+                                   height,
+                                   TRUE, 1.0, 1.0,
+                                   &preview_width,
+                                   &preview_height,
+                                   NULL);
+
+  if (preview_width < pixbuf_width || preview_height < pixbuf_height)
+    {
+      GdkPixbuf *scaled = gdk_pixbuf_scale_simple (pixbuf,
+                                                   preview_width,
+                                                   preview_height,
+                                                   GDK_INTERP_BILINEAR);
+      g_object_unref (pixbuf);
+      pixbuf = scaled;
+
+      pixbuf_width  = preview_width;
+      pixbuf_height = preview_height;
+    }
+
+  if (gdk_pixbuf_get_n_channels (pixbuf) != 3)
+    {
+      GdkPixbuf *tmp = gdk_pixbuf_new (GDK_COLORSPACE_RGB, FALSE, 8,
+                                       pixbuf_width, pixbuf_height);
+
+      gdk_pixbuf_composite_color (pixbuf, tmp,
+                                  0, 0, pixbuf_width, pixbuf_height,
+                                  0.0, 0.0, 1.0, 1.0,
+                                  GDK_INTERP_NEAREST, 255,
+                                  0, 0, GIMP_CHECK_SIZE_SM,
+                                  0x66666666, 0x99999999);
+
+      g_object_unref (pixbuf);
+      pixbuf = tmp;
+    }
+
+  return pixbuf;
+}
+
+static gboolean
+gimp_imagefile_save_thumb (GimpImagefile  *imagefile,
+                           GimpImage      *image,
+                           gint            size,
+                           gboolean        replace,
+                           GError        **error)
+{
+  GimpImagefilePrivate *private   = GET_PRIVATE (imagefile);
+  GimpThumbnail        *thumbnail = private->thumbnail;
+  GdkPixbuf            *pixbuf;
+  gint                  width, height;
+  gboolean              success = FALSE;
+
+  if (size < 1)
+    return TRUE;
+
+  if (gimp_image_get_width  (image) <= size &&
+      gimp_image_get_height (image) <= size)
+    {
+      width  = gimp_image_get_width  (image);
+      height = gimp_image_get_height (image);
+
+      size = MAX (width, height);
+    }
+  else
+    {
+      if (gimp_image_get_width (image) < gimp_image_get_height (image))
+        {
+          height = size;
+          width  = MAX (1, (size * gimp_image_get_width (image) /
+                            gimp_image_get_height (image)));
+        }
+      else
+        {
+          width  = size;
+          height = MAX (1, (size * gimp_image_get_height (image) /
+                            gimp_image_get_width (image)));
+        }
+    }
+
+  /*  we need the projection constructed NOW, not some time later  */
+  gimp_pickable_flush (GIMP_PICKABLE (image));
+
+  pixbuf = gimp_viewable_get_new_pixbuf (GIMP_VIEWABLE (image),
+                                         /* random context, unused */
+                                         gimp_get_user_context (image->gimp),
+                                         width, height);
+
+  /*  when layer previews are disabled, we won't get a pixbuf  */
+  if (! pixbuf)
+    return TRUE;
+
+  success = gimp_thumbnail_save_thumb (thumbnail,
+                                       pixbuf,
+                                       "GIMP " GIMP_VERSION,
+                                       error);
+
+  g_object_unref (pixbuf);
+
+  if (success)
+    {
+      if (replace)
+        gimp_thumbnail_delete_others (thumbnail, size);
+      else
+        gimp_thumbnail_delete_failure (thumbnail);
+
+      gimp_imagefile_update (imagefile);
+    }
+
+  return success;
+}
+
+static void
+gimp_thumbnail_set_info_from_image (GimpThumbnail *thumbnail,
+                                    const gchar   *mime_type,
+                                    GimpImage     *image)
+{
+  const Babl *format;
+
+  /*  peek the thumbnail to make sure that mtime and filesize are set  */
+  gimp_thumbnail_peek_image (thumbnail);
+
+  format = gimp_image_get_layer_format (image,
+                                        gimp_image_has_alpha (image));
+
+  g_object_set (thumbnail,
+                "image-mimetype",   mime_type,
+                "image-width",      gimp_image_get_width  (image),
+                "image-height",     gimp_image_get_height (image),
+                "image-type",       gimp_babl_format_get_description (format),
+                "image-num-layers", gimp_image_get_n_layers (image),
+                NULL);
+}
+
+/**
+ * gimp_thumbnail_set_info:
+ * @thumbnail: #GimpThumbnail object
+ * @mime_type:  MIME type of the image associated with this thumbnail
+ * @width:      width of the image associated with this thumbnail
+ * @height:     height of the image associated with this thumbnail
+ * @format:     format of the image (or NULL if the type is not known)
+ * @num_layers: number of layers in the image
+ *              (or -1 if the number of layers is not known)
+ *
+ * Set information about the image associated with the @thumbnail object.
+ */
+static void
+gimp_thumbnail_set_info (GimpThumbnail *thumbnail,
+                         const gchar   *mime_type,
+                         gint           width,
+                         gint           height,
+                         const Babl    *format,
+                         gint           num_layers)
+{
+  /*  peek the thumbnail to make sure that mtime and filesize are set  */
+  gimp_thumbnail_peek_image (thumbnail);
+
+  g_object_set (thumbnail,
+                "image-mimetype", mime_type,
+                "image-width",    width,
+                "image-height",   height,
+                NULL);
+
+  if (format)
+    g_object_set (thumbnail,
+                  "image-type", gimp_babl_format_get_description (format),
+                  NULL);
+
+  if (num_layers != -1)
+    g_object_set (thumbnail,
+                  "image-num-layers", num_layers,
+                  NULL);
+}
diff --git a/app/core/gimpimagefile.h b/app/core/gimpimagefile.h
new file mode 100644
index 0000000..9ea29b0
--- /dev/null
+++ b/app/core/gimpimagefile.h
@@ -0,0 +1,90 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpimagefile.h
+ *
+ * Thumbnail handling according to the Thumbnail Managing Standard.
+ * https://specifications.freedesktop.org/thumbnail-spec/
+ *
+ * Copyright (C) 2001-2002  Sven Neumann <sven@gimp.org>
+ *                          Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_IMAGEFILE_H__
+#define __GIMP_IMAGEFILE_H__
+
+
+#include "gimpviewable.h"
+
+
+#define GIMP_TYPE_IMAGEFILE            (gimp_imagefile_get_type ())
+#define GIMP_IMAGEFILE(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_IMAGEFILE, GimpImagefile))
+#define GIMP_IMAGEFILE_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_IMAGEFILE, GimpImagefileClass))
+#define GIMP_IS_IMAGEFILE(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_IMAGEFILE))
+#define GIMP_IS_IMAGEFILE_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_IMAGEFILE))
+#define GIMP_IMAGEFILE_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_IMAGEFILE, GimpImagefileClass))
+
+
+typedef struct _GimpImagefileClass GimpImagefileClass;
+
+struct _GimpImagefile
+{
+  GimpViewable  parent_instance;
+};
+
+struct _GimpImagefileClass
+{
+  GimpViewableClass   parent_class;
+
+  void (* info_changed) (GimpImagefile *imagefile);
+};
+
+
+GType           gimp_imagefile_get_type              (void) G_GNUC_CONST;
+
+GimpImagefile * gimp_imagefile_new                   (Gimp           *gimp,
+                                                      GFile          *file);
+
+GFile         * gimp_imagefile_get_file              (GimpImagefile  *imagefile);
+void            gimp_imagefile_set_file              (GimpImagefile  *imagefile,
+                                                      GFile          *file);
+
+GimpThumbnail * gimp_imagefile_get_thumbnail         (GimpImagefile  *imagefile);
+GIcon         * gimp_imagefile_get_gicon             (GimpImagefile  *imagefile);
+
+void            gimp_imagefile_set_mime_type         (GimpImagefile  *imagefile,
+                                                      const gchar    *mime_type);
+void            gimp_imagefile_update                (GimpImagefile  *imagefile);
+gboolean        gimp_imagefile_create_thumbnail      (GimpImagefile  *imagefile,
+                                                      GimpContext    *context,
+                                                      GimpProgress   *progress,
+                                                      gint            size,
+                                                      gboolean        replace,
+                                                      GError        **error);
+void            gimp_imagefile_create_thumbnail_weak (GimpImagefile  *imagefile,
+                                                      GimpContext    *context,
+                                                      GimpProgress   *progress,
+                                                      gint            size,
+                                                      gboolean        replace);
+gboolean        gimp_imagefile_check_thumbnail       (GimpImagefile  *imagefile);
+gboolean        gimp_imagefile_save_thumbnail        (GimpImagefile  *imagefile,
+                                                      const gchar    *mime_type,
+                                                      GimpImage      *image,
+                                                      GError        **error);
+const gchar   * gimp_imagefile_get_desc_string       (GimpImagefile  *imagefile);
+
+
+#endif /* __GIMP_IMAGEFILE_H__ */
diff --git a/app/core/gimpimageproxy.c b/app/core/gimpimageproxy.c
new file mode 100644
index 0000000..6007d6c
--- /dev/null
+++ b/app/core/gimpimageproxy.c
@@ -0,0 +1,877 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpimageproxy.c
+ * Copyright (C) 2019 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <cairo.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpcolor/gimpcolor.h"
+
+#include "core-types.h"
+
+#include "gegl/gimp-babl.h"
+#include "gegl/gimp-gegl-loops.h"
+
+#include "gimpimage.h"
+#include "gimpimage-color-profile.h"
+#include "gimpimage-preview.h"
+#include "gimpimageproxy.h"
+#include "gimppickable.h"
+#include "gimpprojectable.h"
+#include "gimptempbuf.h"
+
+
+enum
+{
+  PROP_0,
+  PROP_IMAGE,
+  PROP_SHOW_ALL,
+  PROP_BUFFER
+};
+
+
+struct _GimpImageProxyPrivate
+{
+  GimpImage     *image;
+  gboolean       show_all;
+
+  GeglRectangle  bounding_box;
+  gboolean       frozen;
+};
+
+
+/*  local function prototypes  */
+
+static void               gimp_image_proxy_pickable_iface_init      (GimpPickableInterface      *iface);
+static void               gimp_image_proxy_color_managed_iface_init (GimpColorManagedInterface  *iface);
+
+static void               gimp_image_proxy_finalize                 (GObject                    *object);
+static void               gimp_image_proxy_set_property             (GObject                    *object,
+                                                                     guint                       property_id,
+                                                                     const GValue               *value,
+                                                                     GParamSpec                 *pspec);
+static void               gimp_image_proxy_get_property             (GObject                    *object,
+                                                                     guint                       property_id,
+                                                                     GValue                     *value,
+                                                                     GParamSpec                 *pspec);
+
+static gboolean           gimp_image_proxy_get_size                 (GimpViewable               *viewable,
+                                                                     gint                       *width,
+                                                                     gint                       *height);
+static void               gimp_image_proxy_get_preview_size         (GimpViewable               *viewable,
+                                                                     gint                        size,
+                                                                     gboolean                    is_popup,
+                                                                     gboolean                    dot_for_dot,
+                                                                     gint                       *width,
+                                                                     gint                       *height);
+static gboolean           gimp_image_proxy_get_popup_size           (GimpViewable               *viewable,
+                                                                     gint                        width,
+                                                                     gint                        height,
+                                                                     gboolean                    dot_for_dot,
+                                                                     gint                       *popup_width,
+                                                                     gint                       *popup_height);
+static GimpTempBuf      * gimp_image_proxy_get_new_preview          (GimpViewable               *viewable,
+                                                                     GimpContext                *context,
+                                                                     gint                        width,
+                                                                     gint                        height);
+static GdkPixbuf        * gimp_image_proxy_get_new_pixbuf           (GimpViewable               *viewable,
+                                                                     GimpContext                *context,
+                                                                     gint                        width,
+                                                                     gint                        height);
+static gchar            * gimp_image_proxy_get_description          (GimpViewable               *viewable,
+                                                                     gchar                     **tooltip);
+
+static void               gimp_image_proxy_flush                    (GimpPickable               *pickable);
+static const Babl       * gimp_image_proxy_get_format               (GimpPickable               *pickable);
+static const Babl       * gimp_image_proxy_get_format_with_alpha    (GimpPickable               *pickable);
+static GeglBuffer       * gimp_image_proxy_get_buffer               (GimpPickable               *pickable);
+static gboolean           gimp_image_proxy_get_pixel_at             (GimpPickable               *pickable,
+                                                                     gint                        x,
+                                                                     gint                        y,
+                                                                     const Babl                 *format,
+                                                                     gpointer                    pixel);
+static gdouble            gimp_image_proxy_get_opacity_at           (GimpPickable               *pickable,
+                                                                     gint                        x,
+                                                                     gint                        y);
+static void               gimp_image_proxy_get_pixel_average        (GimpPickable               *pickable,
+                                                                     const GeglRectangle        *rect,
+                                                                     const Babl                 *format,
+                                                                     gpointer                    pixel);
+static void               gimp_image_proxy_pixel_to_srgb            (GimpPickable               *pickable,
+                                                                     const Babl                 *format,
+                                                                     gpointer                    pixel,
+                                                                     GimpRGB                    *color);
+static void               gimp_image_proxy_srgb_to_pixel            (GimpPickable               *pickable,
+                                                                     const GimpRGB              *color,
+                                                                     const Babl                 *format,
+                                                                     gpointer                    pixel);
+
+static const guint8     * gimp_image_proxy_get_icc_profile          (GimpColorManaged           *managed,
+                                                                     gsize                      *len);
+static GimpColorProfile * gimp_image_proxy_get_color_profile        (GimpColorManaged           *managed);
+static void               gimp_image_proxy_profile_changed          (GimpColorManaged           *managed);
+
+static void               gimp_image_proxy_image_frozen_notify      (GimpImage                  *image,
+                                                                     const GParamSpec           *pspec,
+                                                                     GimpImageProxy             *image_proxy);
+static void               gimp_image_proxy_image_invalidate_preview (GimpImage                  *image,
+                                                                     GimpImageProxy             *image_proxy);
+static void               gimp_image_proxy_image_size_changed       (GimpImage                  *image,
+                                                                     GimpImageProxy             *image_proxy);
+static void               gimp_image_proxy_image_bounds_changed     (GimpImage                  *image,
+                                                                     gint                        old_x,
+                                                                     gint                        old_y,
+                                                                     GimpImageProxy             *image_proxy);
+static void               gimp_image_proxy_image_profile_changed    (GimpImage                  *image,
+                                                                     GimpImageProxy             *image_proxy);
+
+static void               gimp_image_proxy_set_image                (GimpImageProxy             *image_proxy,
+                                                                     GimpImage                  *image);
+static GimpPickable     * gimp_image_proxy_get_pickable             (GimpImageProxy             *image_proxy);
+static void               gimp_image_proxy_update_bounding_box      (GimpImageProxy             *image_proxy);
+static void               gimp_image_proxy_update_frozen            (GimpImageProxy             *image_proxy);
+
+
+G_DEFINE_TYPE_WITH_CODE (GimpImageProxy, gimp_image_proxy, GIMP_TYPE_VIEWABLE,
+                         G_ADD_PRIVATE (GimpImageProxy)
+                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_PICKABLE,
+                                                gimp_image_proxy_pickable_iface_init)
+                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_COLOR_MANAGED,
+                                                gimp_image_proxy_color_managed_iface_init))
+
+#define parent_class gimp_image_proxy_parent_class
+
+
+/*  private functions  */
+
+
+static void
+gimp_image_proxy_class_init (GimpImageProxyClass *klass)
+{
+  GObjectClass      *object_class   = G_OBJECT_CLASS (klass);
+  GimpViewableClass *viewable_class = GIMP_VIEWABLE_CLASS (klass);
+
+  object_class->finalize            = gimp_image_proxy_finalize;
+  object_class->set_property        = gimp_image_proxy_set_property;
+  object_class->get_property        = gimp_image_proxy_get_property;
+
+  viewable_class->default_icon_name = "gimp-image";
+  viewable_class->get_size          = gimp_image_proxy_get_size;
+  viewable_class->get_preview_size  = gimp_image_proxy_get_preview_size;
+  viewable_class->get_popup_size    = gimp_image_proxy_get_popup_size;
+  viewable_class->get_new_preview   = gimp_image_proxy_get_new_preview;
+  viewable_class->get_new_pixbuf    = gimp_image_proxy_get_new_pixbuf;
+  viewable_class->get_description   = gimp_image_proxy_get_description;
+
+  g_object_class_install_property (object_class, PROP_IMAGE,
+                                   g_param_spec_object ("image",
+                                                        NULL, NULL,
+                                                        GIMP_TYPE_IMAGE,
+                                                        GIMP_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT_ONLY));
+
+  g_object_class_install_property (object_class, PROP_SHOW_ALL,
+                                   g_param_spec_boolean ("show-all",
+                                                         NULL, NULL,
+                                                         FALSE,
+                                                         GIMP_PARAM_READWRITE |
+                                                         G_PARAM_CONSTRUCT));
+
+  g_object_class_override_property (object_class, PROP_BUFFER, "buffer");
+}
+
+static void
+gimp_image_proxy_pickable_iface_init (GimpPickableInterface *iface)
+{
+  iface->flush                 = gimp_image_proxy_flush;
+  iface->get_image             = (gpointer) gimp_image_proxy_get_image;
+  iface->get_format            = gimp_image_proxy_get_format;
+  iface->get_format_with_alpha = gimp_image_proxy_get_format_with_alpha;
+  iface->get_buffer            = gimp_image_proxy_get_buffer;
+  iface->get_pixel_at          = gimp_image_proxy_get_pixel_at;
+  iface->get_opacity_at        = gimp_image_proxy_get_opacity_at;
+  iface->get_pixel_average     = gimp_image_proxy_get_pixel_average;
+  iface->pixel_to_srgb         = gimp_image_proxy_pixel_to_srgb;
+  iface->srgb_to_pixel         = gimp_image_proxy_srgb_to_pixel;
+}
+
+static void
+gimp_image_proxy_color_managed_iface_init (GimpColorManagedInterface *iface)
+{
+  iface->get_icc_profile   = gimp_image_proxy_get_icc_profile;
+  iface->get_color_profile = gimp_image_proxy_get_color_profile;
+  iface->profile_changed   = gimp_image_proxy_profile_changed;
+}
+
+static void
+gimp_image_proxy_init (GimpImageProxy *image_proxy)
+{
+  image_proxy->priv = gimp_image_proxy_get_instance_private (image_proxy);
+}
+
+static void
+gimp_image_proxy_finalize (GObject *object)
+{
+  GimpImageProxy *image_proxy = GIMP_IMAGE_PROXY (object);
+
+  gimp_image_proxy_set_image (image_proxy, NULL);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gimp_image_proxy_set_property (GObject      *object,
+                               guint         property_id,
+                               const GValue *value,
+                               GParamSpec   *pspec)
+{
+  GimpImageProxy *image_proxy = GIMP_IMAGE_PROXY (object);
+
+  switch (property_id)
+    {
+    case PROP_IMAGE:
+      gimp_image_proxy_set_image (image_proxy,
+                                  g_value_get_object (value));
+      break;
+
+    case PROP_SHOW_ALL:
+      gimp_image_proxy_set_show_all (image_proxy,
+                                     g_value_get_boolean (value));
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_image_proxy_get_property (GObject    *object,
+                               guint       property_id,
+                               GValue     *value,
+                               GParamSpec *pspec)
+{
+  GimpImageProxy *image_proxy = GIMP_IMAGE_PROXY (object);
+
+  switch (property_id)
+    {
+    case PROP_IMAGE:
+      g_value_set_object (value,
+                          gimp_image_proxy_get_image (image_proxy));
+      break;
+
+    case PROP_SHOW_ALL:
+      g_value_set_boolean (value,
+                           gimp_image_proxy_get_show_all (image_proxy));
+      break;
+
+    case PROP_BUFFER:
+      g_value_set_object (value,
+                          gimp_pickable_get_buffer (
+                            GIMP_PICKABLE (image_proxy)));
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static gboolean
+gimp_image_proxy_get_size (GimpViewable *viewable,
+                           gint         *width,
+                           gint         *height)
+{
+  GimpImageProxy *image_proxy = GIMP_IMAGE_PROXY (viewable);
+
+  *width  = image_proxy->priv->bounding_box.width;
+  *height = image_proxy->priv->bounding_box.height;
+
+  return TRUE;
+}
+
+static void
+gimp_image_proxy_get_preview_size (GimpViewable *viewable,
+                                   gint          size,
+                                   gboolean      is_popup,
+                                   gboolean      dot_for_dot,
+                                   gint         *width,
+                                   gint         *height)
+{
+  GimpImageProxy *image_proxy = GIMP_IMAGE_PROXY (viewable);
+  GimpImage      *image       = image_proxy->priv->image;
+  gdouble         xres;
+  gdouble         yres;
+  gint            viewable_width;
+  gint            viewable_height;
+
+  gimp_image_get_resolution (image, &xres, &yres);
+
+  gimp_viewable_get_size (viewable, &viewable_width, &viewable_height);
+
+  gimp_viewable_calc_preview_size (viewable_width,
+                                   viewable_height,
+                                   size,
+                                   size,
+                                   dot_for_dot,
+                                   xres,
+                                   yres,
+                                   width,
+                                   height,
+                                   NULL);
+}
+
+static gboolean
+gimp_image_proxy_get_popup_size (GimpViewable *viewable,
+                                 gint          width,
+                                 gint          height,
+                                 gboolean      dot_for_dot,
+                                 gint         *popup_width,
+                                 gint         *popup_height)
+{
+  gint viewable_width;
+  gint viewable_height;
+
+  gimp_viewable_get_size (viewable, &viewable_width, &viewable_height);
+
+  if (viewable_width > width || viewable_height > height)
+    {
+      gboolean scaling_up;
+
+      gimp_viewable_calc_preview_size (viewable_width,
+                                       viewable_height,
+                                       width  * 2,
+                                       height * 2,
+                                       dot_for_dot, 1.0, 1.0,
+                                       popup_width,
+                                       popup_height,
+                                       &scaling_up);
+
+      if (scaling_up)
+        {
+          *popup_width  = viewable_width;
+          *popup_height = viewable_height;
+        }
+
+      return TRUE;
+    }
+
+  return FALSE;
+}
+
+static GimpTempBuf *
+gimp_image_proxy_get_new_preview (GimpViewable *viewable,
+                                  GimpContext  *context,
+                                  gint          width,
+                                  gint          height)
+{
+  GimpImageProxy *image_proxy = GIMP_IMAGE_PROXY (viewable);
+  GimpImage      *image       = image_proxy->priv->image;
+  GimpPickable   *pickable;
+  const Babl     *format;
+  GeglRectangle   bounding_box;
+  GimpTempBuf    *buf;
+  gdouble         scale_x;
+  gdouble         scale_y;
+  gdouble         scale;
+
+  pickable     = gimp_image_proxy_get_pickable     (image_proxy);
+  bounding_box = gimp_image_proxy_get_bounding_box (image_proxy);
+
+  scale_x = (gdouble) width  / (gdouble) bounding_box.width;
+  scale_y = (gdouble) height / (gdouble) bounding_box.height;
+
+  scale   = MIN (scale_x, scale_y);
+
+  format = gimp_image_get_preview_format (image);
+
+  buf = gimp_temp_buf_new (width, height, format);
+
+  gegl_buffer_get (gimp_pickable_get_buffer (pickable),
+                   GEGL_RECTANGLE (bounding_box.x * scale,
+                                   bounding_box.y * scale,
+                                   width,
+                                   height),
+                   scale,
+                   gimp_temp_buf_get_format (buf),
+                   gimp_temp_buf_get_data (buf),
+                   GEGL_AUTO_ROWSTRIDE, GEGL_ABYSS_CLAMP);
+
+  return buf;
+}
+
+static GdkPixbuf *
+gimp_image_proxy_get_new_pixbuf (GimpViewable *viewable,
+                                 GimpContext  *context,
+                                 gint          width,
+                                 gint          height)
+{
+  GimpImageProxy     *image_proxy = GIMP_IMAGE_PROXY (viewable);
+  GimpImage          *image       = image_proxy->priv->image;
+  GimpPickable       *pickable;
+  GeglRectangle       bounding_box;
+  GdkPixbuf          *pixbuf;
+  gdouble             scale_x;
+  gdouble             scale_y;
+  gdouble             scale;
+  GimpColorTransform *transform;
+
+  pickable     = gimp_image_proxy_get_pickable     (image_proxy);
+  bounding_box = gimp_image_proxy_get_bounding_box (image_proxy);
+
+  scale_x = (gdouble) width  / (gdouble) bounding_box.width;
+  scale_y = (gdouble) height / (gdouble) bounding_box.height;
+
+  scale   = MIN (scale_x, scale_y);
+
+  pixbuf = gdk_pixbuf_new (GDK_COLORSPACE_RGB, TRUE, 8,
+                           width, height);
+
+  transform = gimp_image_get_color_transform_to_srgb_u8 (image);
+
+  if (transform)
+    {
+      GimpTempBuf *temp_buf;
+      GeglBuffer  *src_buf;
+      GeglBuffer  *dest_buf;
+
+      temp_buf = gimp_temp_buf_new (width, height,
+                                    gimp_pickable_get_format (pickable));
+
+      gegl_buffer_get (gimp_pickable_get_buffer (pickable),
+                       GEGL_RECTANGLE (bounding_box.x * scale,
+                                       bounding_box.y * scale,
+                                       width,
+                                       height),
+                       scale,
+                       gimp_temp_buf_get_format (temp_buf),
+                       gimp_temp_buf_get_data (temp_buf),
+                       GEGL_AUTO_ROWSTRIDE, GEGL_ABYSS_CLAMP);
+
+      src_buf  = gimp_temp_buf_create_buffer (temp_buf);
+      dest_buf = gimp_pixbuf_create_buffer (pixbuf);
+
+      gimp_temp_buf_unref (temp_buf);
+
+      gimp_color_transform_process_buffer (transform,
+                                           src_buf,
+                                           GEGL_RECTANGLE (0, 0,
+                                                           width, height),
+                                           dest_buf,
+                                           GEGL_RECTANGLE (0, 0, 0, 0));
+
+      g_object_unref (src_buf);
+      g_object_unref (dest_buf);
+    }
+  else
+    {
+      gegl_buffer_get (gimp_pickable_get_buffer (pickable),
+                       GEGL_RECTANGLE (bounding_box.x * scale,
+                                       bounding_box.y * scale,
+                                       width,
+                                       height),
+                       scale,
+                       gimp_pixbuf_get_format (pixbuf),
+                       gdk_pixbuf_get_pixels (pixbuf),
+                       gdk_pixbuf_get_rowstride (pixbuf),
+                       GEGL_ABYSS_CLAMP);
+    }
+
+  return pixbuf;
+}
+
+static gchar *
+gimp_image_proxy_get_description (GimpViewable  *viewable,
+                                  gchar        **tooltip)
+{
+  GimpImageProxy *image_proxy = GIMP_IMAGE_PROXY (viewable);
+  GimpImage      *image       = image_proxy->priv->image;
+
+  if (tooltip)
+    *tooltip = g_strdup (gimp_image_get_display_path (image));
+
+  return g_strdup_printf ("%s-%d",
+                          gimp_image_get_display_name (image),
+                          gimp_image_get_ID (image));
+}
+
+static void
+gimp_image_proxy_flush (GimpPickable *pickable)
+{
+  GimpImageProxy *image_proxy = GIMP_IMAGE_PROXY (pickable);
+  GimpPickable   *proxy_pickable;
+
+  proxy_pickable = gimp_image_proxy_get_pickable (image_proxy);
+
+  gimp_pickable_flush (proxy_pickable);
+}
+
+static const Babl *
+gimp_image_proxy_get_format (GimpPickable *pickable)
+{
+  GimpImageProxy *image_proxy = GIMP_IMAGE_PROXY (pickable);
+  GimpPickable   *proxy_pickable;
+
+  proxy_pickable = gimp_image_proxy_get_pickable (image_proxy);
+
+  return gimp_pickable_get_format (proxy_pickable);
+}
+
+static const Babl *
+gimp_image_proxy_get_format_with_alpha (GimpPickable *pickable)
+{
+  GimpImageProxy *image_proxy = GIMP_IMAGE_PROXY (pickable);
+  GimpPickable   *proxy_pickable;
+
+  proxy_pickable = gimp_image_proxy_get_pickable (image_proxy);
+
+  return gimp_pickable_get_format_with_alpha (proxy_pickable);
+}
+
+static GeglBuffer *
+gimp_image_proxy_get_buffer (GimpPickable *pickable)
+{
+  GimpImageProxy *image_proxy = GIMP_IMAGE_PROXY (pickable);
+  GimpPickable   *proxy_pickable;
+
+  proxy_pickable = gimp_image_proxy_get_pickable (image_proxy);
+
+  return gimp_pickable_get_buffer (proxy_pickable);
+}
+
+static gboolean
+gimp_image_proxy_get_pixel_at (GimpPickable *pickable,
+                               gint          x,
+                               gint          y,
+                               const Babl   *format,
+                               gpointer      pixel)
+{
+  GimpImageProxy *image_proxy = GIMP_IMAGE_PROXY (pickable);
+  GimpPickable   *proxy_pickable;
+
+  proxy_pickable = gimp_image_proxy_get_pickable (image_proxy);
+
+  return gimp_pickable_get_pixel_at (proxy_pickable, x, y, format, pixel);
+}
+
+static gdouble
+gimp_image_proxy_get_opacity_at (GimpPickable *pickable,
+                                 gint          x,
+                                 gint          y)
+{
+  GimpImageProxy *image_proxy = GIMP_IMAGE_PROXY (pickable);
+  GimpPickable   *proxy_pickable;
+
+  proxy_pickable = gimp_image_proxy_get_pickable (image_proxy);
+
+  return gimp_pickable_get_opacity_at (proxy_pickable, x, y);
+}
+
+static void
+gimp_image_proxy_get_pixel_average (GimpPickable        *pickable,
+                                    const GeglRectangle *rect,
+                                    const Babl          *format,
+                                    gpointer             pixel)
+{
+  GimpImageProxy *image_proxy = GIMP_IMAGE_PROXY (pickable);
+  GimpPickable   *proxy_pickable;
+
+  proxy_pickable = gimp_image_proxy_get_pickable (image_proxy);
+
+  gimp_pickable_get_pixel_average (proxy_pickable, rect, format, pixel);
+}
+
+static void
+gimp_image_proxy_pixel_to_srgb (GimpPickable *pickable,
+                                const Babl   *format,
+                                gpointer      pixel,
+                                GimpRGB      *color)
+{
+  GimpImageProxy *image_proxy = GIMP_IMAGE_PROXY (pickable);
+  GimpPickable   *proxy_pickable;
+
+  proxy_pickable = gimp_image_proxy_get_pickable (image_proxy);
+
+  gimp_pickable_pixel_to_srgb (proxy_pickable, format, pixel, color);
+}
+
+static void
+gimp_image_proxy_srgb_to_pixel (GimpPickable  *pickable,
+                                const GimpRGB *color,
+                                const Babl    *format,
+                                gpointer       pixel)
+{
+  GimpImageProxy *image_proxy = GIMP_IMAGE_PROXY (pickable);
+  GimpPickable   *proxy_pickable;
+
+  proxy_pickable = gimp_image_proxy_get_pickable (image_proxy);
+
+  gimp_pickable_srgb_to_pixel (proxy_pickable, color, format, pixel);
+}
+
+static const guint8 *
+gimp_image_proxy_get_icc_profile (GimpColorManaged *managed,
+                                  gsize            *len)
+{
+  GimpImageProxy *image_proxy = GIMP_IMAGE_PROXY (managed);
+
+  return gimp_color_managed_get_icc_profile (
+    GIMP_COLOR_MANAGED (image_proxy->priv->image),
+    len);
+}
+
+static GimpColorProfile *
+gimp_image_proxy_get_color_profile (GimpColorManaged *managed)
+{
+  GimpImageProxy *image_proxy = GIMP_IMAGE_PROXY (managed);
+
+  return gimp_color_managed_get_color_profile (
+    GIMP_COLOR_MANAGED (image_proxy->priv->image));
+}
+
+static void
+gimp_image_proxy_profile_changed (GimpColorManaged *managed)
+{
+  gimp_viewable_invalidate_preview (GIMP_VIEWABLE (managed));
+}
+
+static void
+gimp_image_proxy_image_frozen_notify (GimpImage        *image,
+                                      const GParamSpec *pspec,
+                                      GimpImageProxy   *image_proxy)
+{
+  gimp_image_proxy_update_frozen (image_proxy);
+}
+
+static void
+gimp_image_proxy_image_invalidate_preview (GimpImage      *image,
+                                           GimpImageProxy *image_proxy)
+{
+  gimp_viewable_invalidate_preview (GIMP_VIEWABLE (image_proxy));
+}
+
+static void
+gimp_image_proxy_image_size_changed (GimpImage      *image,
+                                     GimpImageProxy *image_proxy)
+{
+  gimp_image_proxy_update_bounding_box (image_proxy);
+}
+
+static void
+gimp_image_proxy_image_bounds_changed (GimpImage      *image,
+                                       gint            old_x,
+                                       gint            old_y,
+                                       GimpImageProxy *image_proxy)
+{
+  gimp_image_proxy_update_bounding_box (image_proxy);
+}
+
+static void
+gimp_image_proxy_image_profile_changed (GimpImage      *image,
+                                        GimpImageProxy *image_proxy)
+{
+  gimp_color_managed_profile_changed (GIMP_COLOR_MANAGED (image_proxy));
+}
+
+static void
+gimp_image_proxy_set_image (GimpImageProxy *image_proxy,
+                            GimpImage      *image)
+{
+  if (image_proxy->priv->image)
+    {
+      g_signal_handlers_disconnect_by_func (
+        image_proxy->priv->image,
+        gimp_image_proxy_image_frozen_notify,
+        image_proxy);
+      g_signal_handlers_disconnect_by_func (
+        image_proxy->priv->image,
+        gimp_image_proxy_image_invalidate_preview,
+        image_proxy);
+      g_signal_handlers_disconnect_by_func (
+        image_proxy->priv->image,
+        gimp_image_proxy_image_size_changed,
+        image_proxy);
+      g_signal_handlers_disconnect_by_func (
+        image_proxy->priv->image,
+        gimp_image_proxy_image_bounds_changed,
+        image_proxy);
+      g_signal_handlers_disconnect_by_func (
+        image_proxy->priv->image,
+        gimp_image_proxy_image_profile_changed,
+        image_proxy);
+
+      g_object_unref (image_proxy->priv->image);
+    }
+
+  image_proxy->priv->image = image;
+
+  if (image_proxy->priv->image)
+    {
+      g_object_ref (image_proxy->priv->image);
+
+      g_signal_connect (
+        image_proxy->priv->image, "notify::frozen",
+        G_CALLBACK (gimp_image_proxy_image_frozen_notify),
+        image_proxy);
+      g_signal_connect (
+        image_proxy->priv->image, "invalidate-preview",
+        G_CALLBACK (gimp_image_proxy_image_invalidate_preview),
+        image_proxy);
+      g_signal_connect (
+        image_proxy->priv->image, "size-changed",
+        G_CALLBACK (gimp_image_proxy_image_size_changed),
+        image_proxy);
+      g_signal_connect (
+        image_proxy->priv->image, "bounds-changed",
+        G_CALLBACK (gimp_image_proxy_image_bounds_changed),
+        image_proxy);
+      g_signal_connect (
+        image_proxy->priv->image, "profile-changed",
+        G_CALLBACK (gimp_image_proxy_image_profile_changed),
+        image_proxy);
+
+      gimp_image_proxy_update_bounding_box (image_proxy);
+      gimp_image_proxy_update_frozen (image_proxy);
+
+      gimp_viewable_invalidate_preview (GIMP_VIEWABLE (image_proxy));
+    }
+}
+
+static GimpPickable *
+gimp_image_proxy_get_pickable (GimpImageProxy *image_proxy)
+{
+  GimpImage *image = image_proxy->priv->image;
+
+  if (! image_proxy->priv->show_all)
+    return GIMP_PICKABLE (image);
+  else
+    return GIMP_PICKABLE (gimp_image_get_projection (image));
+}
+
+static void
+gimp_image_proxy_update_bounding_box (GimpImageProxy *image_proxy)
+{
+  GimpImage     *image = image_proxy->priv->image;
+  GeglRectangle  bounding_box;
+
+  if (gimp_viewable_preview_is_frozen (GIMP_VIEWABLE (image_proxy)))
+    return;
+
+  if (! image_proxy->priv->show_all)
+    {
+      bounding_box.x      = 0;
+      bounding_box.y      = 0;
+      bounding_box.width  = gimp_image_get_width  (image);
+      bounding_box.height = gimp_image_get_height (image);
+    }
+  else
+    {
+      bounding_box = gimp_projectable_get_bounding_box (
+        GIMP_PROJECTABLE (image));
+    }
+
+  if (! gegl_rectangle_equal (&bounding_box,
+                              &image_proxy->priv->bounding_box))
+    {
+      image_proxy->priv->bounding_box = bounding_box;
+
+      gimp_viewable_size_changed (GIMP_VIEWABLE (image_proxy));
+    }
+}
+
+static void
+gimp_image_proxy_update_frozen (GimpImageProxy *image_proxy)
+{
+  gboolean frozen;
+
+  frozen = gimp_viewable_preview_is_frozen (
+    GIMP_VIEWABLE (image_proxy->priv->image));
+
+  if (frozen != image_proxy->priv->frozen)
+    {
+      image_proxy->priv->frozen = frozen;
+
+      if (frozen)
+        {
+          gimp_viewable_preview_freeze (GIMP_VIEWABLE (image_proxy));
+        }
+      else
+        {
+          gimp_viewable_preview_thaw (GIMP_VIEWABLE (image_proxy));
+
+          gimp_image_proxy_update_bounding_box (image_proxy);
+        }
+    }
+}
+
+
+/*  public functions  */
+
+
+GimpImageProxy *
+gimp_image_proxy_new (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  return g_object_new (GIMP_TYPE_IMAGE_PROXY,
+                       "image", image,
+                       NULL);
+}
+
+GimpImage *
+gimp_image_proxy_get_image (GimpImageProxy *image_proxy)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE_PROXY (image_proxy), NULL);
+
+  return image_proxy->priv->image;
+}
+
+void
+gimp_image_proxy_set_show_all (GimpImageProxy *image_proxy,
+                               gboolean        show_all)
+{
+  g_return_if_fail (GIMP_IS_IMAGE_PROXY (image_proxy));
+
+  if (show_all != image_proxy->priv->show_all)
+    {
+      image_proxy->priv->show_all = show_all;
+
+      gimp_image_proxy_update_bounding_box (image_proxy);
+    }
+}
+
+gboolean
+gimp_image_proxy_get_show_all (GimpImageProxy *image_proxy)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE_PROXY (image_proxy), FALSE);
+
+  return image_proxy->priv->show_all;
+}
+
+GeglRectangle
+gimp_image_proxy_get_bounding_box (GimpImageProxy *image_proxy)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE_PROXY (image_proxy),
+                        *GEGL_RECTANGLE (0, 0, 0, 0));
+
+  return image_proxy->priv->bounding_box;
+}
diff --git a/app/core/gimpimageproxy.h b/app/core/gimpimageproxy.h
new file mode 100644
index 0000000..a6c9922
--- /dev/null
+++ b/app/core/gimpimageproxy.h
@@ -0,0 +1,65 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpimageproxy.h
+ * Copyright (C) 2019 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_IMAGE_PROXY_H__
+#define __GIMP_IMAGE_PROXY_H__
+
+
+#include "gimpviewable.h"
+
+
+#define GIMP_TYPE_IMAGE_PROXY            (gimp_image_proxy_get_type ())
+#define GIMP_IMAGE_PROXY(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_IMAGE_PROXY, GimpImageProxy))
+#define GIMP_IMAGE_PROXY_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_IMAGE_PROXY, GimpImageProxyClass))
+#define GIMP_IS_IMAGE_PROXY(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_IMAGE_PROXY))
+#define GIMP_IS_IMAGE_PROXY_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_IMAGE_PROXY))
+#define GIMP_IMAGE_PROXY_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_IMAGE_PROXY, GimpImageProxyClass))
+
+
+typedef struct _GimpImageProxyPrivate GimpImageProxyPrivate;
+typedef struct _GimpImageProxyClass   GimpImageProxyClass;
+
+struct _GimpImageProxy
+{
+  GimpViewable           parent_instance;
+
+  GimpImageProxyPrivate *priv;
+};
+
+struct _GimpImageProxyClass
+{
+  GimpViewableClass  parent_class;
+};
+
+
+GType            gimp_image_proxy_get_type         (void) G_GNUC_CONST;
+
+GimpImageProxy * gimp_image_proxy_new              (GimpImage      *image);
+
+GimpImage      * gimp_image_proxy_get_image        (GimpImageProxy *image_proxy);
+              
+void             gimp_image_proxy_set_show_all     (GimpImageProxy *image_proxy,
+                                                    gboolean        show_all);
+gboolean         gimp_image_proxy_get_show_all     (GimpImageProxy *image_proxy);
+              
+GeglRectangle    gimp_image_proxy_get_bounding_box (GimpImageProxy *image_proxy);
+
+
+#endif /* __GIMP_IMAGE_PROXY_H__ */
diff --git a/app/core/gimpimageundo.c b/app/core/gimpimageundo.c
new file mode 100644
index 0000000..8aa9e11
--- /dev/null
+++ b/app/core/gimpimageundo.c
@@ -0,0 +1,535 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <cairo.h>
+#include <gegl.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpcolor/gimpcolor.h"
+#include "libgimpconfig/gimpconfig.h"
+
+#include "core-types.h"
+
+#include "gimp-memsize.h"
+#include "gimpdrawable.h"
+#include "gimpgrid.h"
+#include "gimpimage.h"
+#include "gimpimage-color-profile.h"
+#include "gimpimage-colormap.h"
+#include "gimpimage-grid.h"
+#include "gimpimage-metadata.h"
+#include "gimpimage-private.h"
+#include "gimpimageundo.h"
+
+
+enum
+{
+  PROP_0,
+  PROP_PREVIOUS_ORIGIN_X,
+  PROP_PREVIOUS_ORIGIN_Y,
+  PROP_PREVIOUS_WIDTH,
+  PROP_PREVIOUS_HEIGHT,
+  PROP_GRID,
+  PROP_PARASITE_NAME
+};
+
+
+static void     gimp_image_undo_constructed  (GObject             *object);
+static void     gimp_image_undo_set_property (GObject             *object,
+                                              guint                property_id,
+                                              const GValue        *value,
+                                              GParamSpec          *pspec);
+static void     gimp_image_undo_get_property (GObject             *object,
+                                              guint                property_id,
+                                              GValue              *value,
+                                              GParamSpec          *pspec);
+
+static gint64   gimp_image_undo_get_memsize  (GimpObject          *object,
+                                              gint64              *gui_size);
+
+static void     gimp_image_undo_pop          (GimpUndo            *undo,
+                                              GimpUndoMode         undo_mode,
+                                              GimpUndoAccumulator *accum);
+static void     gimp_image_undo_free         (GimpUndo            *undo,
+                                              GimpUndoMode         undo_mode);
+
+
+G_DEFINE_TYPE (GimpImageUndo, gimp_image_undo, GIMP_TYPE_UNDO)
+
+#define parent_class gimp_image_undo_parent_class
+
+
+static void
+gimp_image_undo_class_init (GimpImageUndoClass *klass)
+{
+  GObjectClass    *object_class      = G_OBJECT_CLASS (klass);
+  GimpObjectClass *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+  GimpUndoClass   *undo_class        = GIMP_UNDO_CLASS (klass);
+
+  object_class->constructed      = gimp_image_undo_constructed;
+  object_class->set_property     = gimp_image_undo_set_property;
+  object_class->get_property     = gimp_image_undo_get_property;
+
+  gimp_object_class->get_memsize = gimp_image_undo_get_memsize;
+
+  undo_class->pop                = gimp_image_undo_pop;
+  undo_class->free               = gimp_image_undo_free;
+
+  g_object_class_install_property (object_class, PROP_PREVIOUS_ORIGIN_X,
+                                   g_param_spec_int ("previous-origin-x",
+                                                     NULL, NULL,
+                                                     -GIMP_MAX_IMAGE_SIZE,
+                                                     GIMP_MAX_IMAGE_SIZE,
+                                                     0,
+                                                     GIMP_PARAM_READWRITE));
+
+  g_object_class_install_property (object_class, PROP_PREVIOUS_ORIGIN_Y,
+                                   g_param_spec_int ("previous-origin-y",
+                                                     NULL, NULL,
+                                                     -GIMP_MAX_IMAGE_SIZE,
+                                                     GIMP_MAX_IMAGE_SIZE,
+                                                     0,
+                                                     GIMP_PARAM_READWRITE));
+
+  g_object_class_install_property (object_class, PROP_PREVIOUS_WIDTH,
+                                   g_param_spec_int ("previous-width",
+                                                     NULL, NULL,
+                                                     -GIMP_MAX_IMAGE_SIZE,
+                                                     GIMP_MAX_IMAGE_SIZE,
+                                                     0,
+                                                     GIMP_PARAM_READWRITE));
+
+  g_object_class_install_property (object_class, PROP_PREVIOUS_HEIGHT,
+                                   g_param_spec_int ("previous-height",
+                                                     NULL, NULL,
+                                                     -GIMP_MAX_IMAGE_SIZE,
+                                                     GIMP_MAX_IMAGE_SIZE,
+                                                     0,
+                                                     GIMP_PARAM_READWRITE));
+
+  g_object_class_install_property (object_class, PROP_GRID,
+                                   g_param_spec_object ("grid", NULL, NULL,
+                                                        GIMP_TYPE_GRID,
+                                                        GIMP_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT_ONLY));
+
+  g_object_class_install_property (object_class, PROP_PARASITE_NAME,
+                                   g_param_spec_string ("parasite-name",
+                                                        NULL, NULL,
+                                                        NULL,
+                                                        GIMP_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT_ONLY));
+}
+
+static void
+gimp_image_undo_init (GimpImageUndo *undo)
+{
+}
+
+static void
+gimp_image_undo_constructed (GObject *object)
+{
+  GimpImageUndo *image_undo = GIMP_IMAGE_UNDO (object);
+  GimpImage     *image;
+
+  G_OBJECT_CLASS (parent_class)->constructed (object);
+
+  image = GIMP_UNDO (object)->image;
+
+  switch (GIMP_UNDO (object)->undo_type)
+    {
+    case GIMP_UNDO_IMAGE_TYPE:
+      image_undo->base_type = gimp_image_get_base_type (image);
+      break;
+
+    case GIMP_UNDO_IMAGE_PRECISION:
+      image_undo->precision = gimp_image_get_precision (image);
+      break;
+
+    case GIMP_UNDO_IMAGE_SIZE:
+      image_undo->width  = gimp_image_get_width  (image);
+      image_undo->height = gimp_image_get_height (image);
+      break;
+
+    case GIMP_UNDO_IMAGE_RESOLUTION:
+      gimp_image_get_resolution (image,
+                                 &image_undo->xresolution,
+                                 &image_undo->yresolution);
+      image_undo->resolution_unit = gimp_image_get_unit (image);
+      break;
+
+    case GIMP_UNDO_IMAGE_GRID:
+      gimp_assert (GIMP_IS_GRID (image_undo->grid));
+      break;
+
+    case GIMP_UNDO_IMAGE_COLORMAP:
+      image_undo->num_colors = gimp_image_get_colormap_size (image);
+      image_undo->colormap   = g_memdup (gimp_image_get_colormap (image),
+                                         GIMP_IMAGE_COLORMAP_SIZE);
+      break;
+
+    case GIMP_UNDO_IMAGE_COLOR_MANAGED:
+      image_undo->is_color_managed = gimp_image_get_is_color_managed (image);
+      break;
+
+    case GIMP_UNDO_IMAGE_METADATA:
+      image_undo->metadata =
+        gimp_metadata_duplicate (gimp_image_get_metadata (image));
+      break;
+
+    case GIMP_UNDO_PARASITE_ATTACH:
+    case GIMP_UNDO_PARASITE_REMOVE:
+      gimp_assert (image_undo->parasite_name != NULL);
+
+      image_undo->parasite = gimp_parasite_copy
+        (gimp_image_parasite_find (image, image_undo->parasite_name));
+      break;
+
+    default:
+      g_return_if_reached ();
+    }
+}
+
+static void
+gimp_image_undo_set_property (GObject      *object,
+                              guint         property_id,
+                              const GValue *value,
+                              GParamSpec   *pspec)
+{
+  GimpImageUndo *image_undo = GIMP_IMAGE_UNDO (object);
+
+  switch (property_id)
+    {
+    case PROP_PREVIOUS_ORIGIN_X:
+      image_undo->previous_origin_x = g_value_get_int (value);
+      break;
+    case PROP_PREVIOUS_ORIGIN_Y:
+      image_undo->previous_origin_y = g_value_get_int (value);
+      break;
+    case PROP_PREVIOUS_WIDTH:
+      image_undo->previous_width = g_value_get_int (value);
+      break;
+    case PROP_PREVIOUS_HEIGHT:
+      image_undo->previous_height = g_value_get_int (value);
+      break;
+    case PROP_GRID:
+      {
+        GimpGrid *grid = g_value_get_object (value);
+
+        if (grid)
+          image_undo->grid = gimp_config_duplicate (GIMP_CONFIG (grid));
+      }
+      break;
+    case PROP_PARASITE_NAME:
+      image_undo->parasite_name = g_value_dup_string (value);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_image_undo_get_property (GObject    *object,
+                              guint       property_id,
+                              GValue     *value,
+                              GParamSpec *pspec)
+{
+  GimpImageUndo *image_undo = GIMP_IMAGE_UNDO (object);
+
+  switch (property_id)
+    {
+    case PROP_PREVIOUS_ORIGIN_X:
+      g_value_set_int (value, image_undo->previous_origin_x);
+      break;
+    case PROP_PREVIOUS_ORIGIN_Y:
+      g_value_set_int (value, image_undo->previous_origin_y);
+      break;
+    case PROP_PREVIOUS_WIDTH:
+      g_value_set_int (value, image_undo->previous_width);
+      break;
+    case PROP_PREVIOUS_HEIGHT:
+      g_value_set_int (value, image_undo->previous_height);
+      break;
+    case PROP_GRID:
+      g_value_set_object (value, image_undo->grid);
+       break;
+    case PROP_PARASITE_NAME:
+      g_value_set_string (value, image_undo->parasite_name);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static gint64
+gimp_image_undo_get_memsize (GimpObject *object,
+                             gint64     *gui_size)
+{
+  GimpImageUndo *image_undo = GIMP_IMAGE_UNDO (object);
+  gint64         memsize    = 0;
+
+  if (image_undo->colormap)
+    memsize += GIMP_IMAGE_COLORMAP_SIZE;
+
+  if (image_undo->metadata)
+    memsize += gimp_g_object_get_memsize (G_OBJECT (image_undo->metadata));
+
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (image_undo->grid),
+                                      gui_size);
+  memsize += gimp_string_get_memsize (image_undo->parasite_name);
+  memsize += gimp_parasite_get_memsize (image_undo->parasite, gui_size);
+
+  return memsize + GIMP_OBJECT_CLASS (parent_class)->get_memsize (object,
+                                                                  gui_size);
+}
+
+static void
+gimp_image_undo_pop (GimpUndo            *undo,
+                     GimpUndoMode         undo_mode,
+                     GimpUndoAccumulator *accum)
+{
+  GimpImageUndo    *image_undo = GIMP_IMAGE_UNDO (undo);
+  GimpImage        *image      = undo->image;
+  GimpImagePrivate *private    = GIMP_IMAGE_GET_PRIVATE (image);
+
+  GIMP_UNDO_CLASS (parent_class)->pop (undo, undo_mode, accum);
+
+  switch (undo->undo_type)
+    {
+    case GIMP_UNDO_IMAGE_TYPE:
+      {
+        GimpImageBaseType base_type;
+
+        base_type = image_undo->base_type;
+        image_undo->base_type = gimp_image_get_base_type (image);
+        g_object_set (image, "base-type", base_type, NULL);
+
+        gimp_image_colormap_changed (image, -1);
+
+        if (image_undo->base_type != gimp_image_get_base_type (image))
+          {
+            if ((image_undo->base_type            == GIMP_GRAY) ||
+                (gimp_image_get_base_type (image) == GIMP_GRAY))
+              {
+                /* in case there was no profile undo, we need to emit
+                 * profile-changed anyway
+                 */
+                gimp_color_managed_profile_changed (GIMP_COLOR_MANAGED (image));
+              }
+
+            accum->mode_changed = TRUE;
+          }
+      }
+      break;
+
+    case GIMP_UNDO_IMAGE_PRECISION:
+      {
+        GimpPrecision precision;
+
+        precision = image_undo->precision;
+        image_undo->precision = gimp_image_get_precision (image);
+        g_object_set (image, "precision", precision, NULL);
+
+        if (image_undo->precision != gimp_image_get_precision (image))
+          accum->precision_changed = TRUE;
+      }
+      break;
+
+    case GIMP_UNDO_IMAGE_SIZE:
+      {
+        gint width;
+        gint height;
+        gint previous_origin_x;
+        gint previous_origin_y;
+        gint previous_width;
+        gint previous_height;
+
+        width             = image_undo->width;
+        height            = image_undo->height;
+        previous_origin_x = image_undo->previous_origin_x;
+        previous_origin_y = image_undo->previous_origin_y;
+        previous_width    = image_undo->previous_width;
+        previous_height   = image_undo->previous_height;
+
+        /* Transform to a redo */
+        image_undo->width             = gimp_image_get_width  (image);
+        image_undo->height            = gimp_image_get_height (image);
+        image_undo->previous_origin_x = -previous_origin_x;
+        image_undo->previous_origin_y = -previous_origin_y;
+        image_undo->previous_width    = width;
+        image_undo->previous_height   = height;
+
+        g_object_set (image,
+                      "width",  width,
+                      "height", height,
+                      NULL);
+
+        gimp_drawable_invalidate_boundary
+          (GIMP_DRAWABLE (gimp_image_get_mask (image)));
+
+        if (gimp_image_get_width  (image) != image_undo->width ||
+            gimp_image_get_height (image) != image_undo->height)
+          {
+            accum->size_changed      = TRUE;
+            accum->previous_origin_x = previous_origin_x;
+            accum->previous_origin_y = previous_origin_y;
+            accum->previous_width    = previous_width;
+            accum->previous_height   = previous_height;
+          }
+      }
+      break;
+
+    case GIMP_UNDO_IMAGE_RESOLUTION:
+      {
+        gdouble xres;
+        gdouble yres;
+
+        gimp_image_get_resolution (image, &xres, &yres);
+
+        if (ABS (image_undo->xresolution - xres) >= 1e-5 ||
+            ABS (image_undo->yresolution - yres) >= 1e-5)
+          {
+            private->xresolution = image_undo->xresolution;
+            private->yresolution = image_undo->yresolution;
+
+            image_undo->xresolution = xres;
+            image_undo->yresolution = yres;
+
+            accum->resolution_changed = TRUE;
+          }
+      }
+
+      if (image_undo->resolution_unit != gimp_image_get_unit (image))
+        {
+          GimpUnit unit;
+
+          unit = gimp_image_get_unit (image);
+          private->resolution_unit = image_undo->resolution_unit;
+          image_undo->resolution_unit = unit;
+
+          accum->unit_changed = TRUE;
+        }
+      break;
+
+    case GIMP_UNDO_IMAGE_GRID:
+      {
+        GimpGrid *grid;
+
+        grid = gimp_config_duplicate (GIMP_CONFIG (gimp_image_get_grid (image)));
+
+        gimp_image_set_grid (image, image_undo->grid, FALSE);
+
+        g_object_unref (image_undo->grid);
+        image_undo->grid = grid;
+      }
+      break;
+
+    case GIMP_UNDO_IMAGE_COLORMAP:
+      {
+        guchar *colormap;
+        gint    num_colors;
+
+        num_colors = gimp_image_get_colormap_size (image);
+        colormap   = g_memdup (gimp_image_get_colormap (image),
+                               GIMP_IMAGE_COLORMAP_SIZE);
+
+        if (image_undo->colormap)
+          gimp_image_set_colormap (image,
+                                   image_undo->colormap, image_undo->num_colors,
+                                   FALSE);
+        else
+          gimp_image_unset_colormap (image, FALSE);
+
+        if (image_undo->colormap)
+          g_free (image_undo->colormap);
+
+        image_undo->num_colors = num_colors;
+        image_undo->colormap   = colormap;
+      }
+      break;
+
+    case GIMP_UNDO_IMAGE_COLOR_MANAGED:
+      {
+        gboolean is_color_managed;
+
+        is_color_managed = gimp_image_get_is_color_managed (image);
+        gimp_image_set_is_color_managed (image, image_undo->is_color_managed,
+                                         FALSE);
+        image_undo->is_color_managed = is_color_managed;
+      }
+      break;
+
+    case GIMP_UNDO_IMAGE_METADATA:
+      {
+        GimpMetadata *metadata;
+
+        metadata = gimp_metadata_duplicate (gimp_image_get_metadata (image));
+
+        gimp_image_set_metadata (image, image_undo->metadata, FALSE);
+
+        if (image_undo->metadata)
+          g_object_unref (image_undo->metadata);
+        image_undo->metadata = metadata;
+      }
+      break;
+
+    case GIMP_UNDO_PARASITE_ATTACH:
+    case GIMP_UNDO_PARASITE_REMOVE:
+      {
+        GimpParasite *parasite = image_undo->parasite;
+
+        image_undo->parasite = gimp_parasite_copy
+          (gimp_image_parasite_find (image, image_undo->parasite_name));
+
+        if (parasite)
+          gimp_image_parasite_attach (image, parasite, FALSE);
+        else
+          gimp_image_parasite_detach (image, image_undo->parasite_name, FALSE);
+
+        if (parasite)
+          gimp_parasite_free (parasite);
+      }
+      break;
+
+    default:
+      g_return_if_reached ();
+    }
+}
+
+static void
+gimp_image_undo_free (GimpUndo     *undo,
+                      GimpUndoMode  undo_mode)
+{
+  GimpImageUndo *image_undo = GIMP_IMAGE_UNDO (undo);
+
+  g_clear_object (&image_undo->grid);
+  g_clear_pointer (&image_undo->colormap, g_free);
+  g_clear_object (&image_undo->metadata);
+  g_clear_pointer (&image_undo->parasite_name, g_free);
+  g_clear_pointer (&image_undo->parasite, gimp_parasite_free);
+
+  GIMP_UNDO_CLASS (parent_class)->free (undo, undo_mode);
+}
diff --git a/app/core/gimpimageundo.h b/app/core/gimpimageundo.h
new file mode 100644
index 0000000..0290b40
--- /dev/null
+++ b/app/core/gimpimageundo.h
@@ -0,0 +1,69 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_IMAGE_UNDO_H__
+#define __GIMP_IMAGE_UNDO_H__
+
+
+#include "gimpundo.h"
+
+
+#define GIMP_TYPE_IMAGE_UNDO            (gimp_image_undo_get_type ())
+#define GIMP_IMAGE_UNDO(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_IMAGE_UNDO, GimpImageUndo))
+#define GIMP_IMAGE_UNDO_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_IMAGE_UNDO, GimpImageUndoClass))
+#define GIMP_IS_IMAGE_UNDO(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_IMAGE_UNDO))
+#define GIMP_IS_IMAGE_UNDO_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_IMAGE_UNDO))
+#define GIMP_IMAGE_UNDO_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_IMAGE_UNDO, GimpImageUndoClass))
+
+
+typedef struct _GimpImageUndo      GimpImageUndo;
+typedef struct _GimpImageUndoClass GimpImageUndoClass;
+
+struct _GimpImageUndo
+{
+  GimpUndo           parent_instance;
+
+  GimpImageBaseType  base_type;
+  GimpPrecision      precision;
+  gint               width;
+  gint               height;
+  gint               previous_origin_x;
+  gint               previous_origin_y;
+  gint               previous_width;
+  gint               previous_height;
+  gdouble            xresolution;
+  gdouble            yresolution;
+  GimpUnit           resolution_unit;
+  GimpGrid          *grid;
+  gint               num_colors;
+  guchar            *colormap;
+  gboolean           is_color_managed;
+  GimpMetadata      *metadata;
+  gchar             *parasite_name;
+  GimpParasite      *parasite;
+};
+
+struct _GimpImageUndoClass
+{
+  GimpUndoClass  parent_class;
+};
+
+
+GType   gimp_image_undo_get_type (void) G_GNUC_CONST;
+
+
+#endif /* __GIMP_IMAGE_UNDO_H__ */
diff --git a/app/core/gimpitem-exclusive.c b/app/core/gimpitem-exclusive.c
new file mode 100644
index 0000000..5cdb45f
--- /dev/null
+++ b/app/core/gimpitem-exclusive.c
@@ -0,0 +1,276 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpitem-exclusive.c
+ * Copyright (C) 2011 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gimpcontext.h"
+#include "gimpimage-undo.h"
+#include "gimpimage-undo-push.h"
+#include "gimpitem.h"
+#include "gimpitem-exclusive.h"
+#include "gimpitemstack.h"
+#include "gimpitemtree.h"
+#include "gimpundostack.h"
+
+#include "gimp-intl.h"
+
+
+static GList * gimp_item_exclusive_get_ancestry (GimpItem     *item);
+static void    gimp_item_exclusive_get_lists    (GimpItem     *item,
+                                                 const gchar  *property,
+                                                 GList       **on,
+                                                 GList       **off);
+
+
+/*  public functions  */
+
+void
+gimp_item_toggle_exclusive_visible (GimpItem    *item,
+                                    GimpContext *context)
+{
+  GList *ancestry;
+  GList *on;
+  GList *off;
+  GList *list;
+
+  g_return_if_fail (GIMP_IS_ITEM (item));
+  g_return_if_fail (gimp_item_is_attached (item));
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  ancestry = gimp_item_exclusive_get_ancestry (item);
+  gimp_item_exclusive_get_lists (item, "visible", &on, &off);
+
+  if (on || off || ! gimp_item_is_visible (item))
+    {
+      GimpImage *image = gimp_item_get_image (item);
+      GimpUndo  *undo;
+      gboolean   push_undo = TRUE;
+
+      undo = gimp_image_undo_can_compress (image, GIMP_TYPE_UNDO_STACK,
+                                           GIMP_UNDO_GROUP_ITEM_VISIBILITY);
+
+      if (undo && (g_object_get_data (G_OBJECT (undo), "exclusive-visible-item") ==
+                   (gpointer) item))
+        push_undo = FALSE;
+
+      if (push_undo)
+        {
+          if (gimp_image_undo_group_start (image,
+                                           GIMP_UNDO_GROUP_ITEM_VISIBILITY,
+                                           _("Set Item Exclusive Visible")))
+            {
+              undo = gimp_image_undo_can_compress (image, GIMP_TYPE_UNDO_STACK,
+                                                   GIMP_UNDO_GROUP_ITEM_VISIBILITY);
+
+              if (undo)
+                g_object_set_data (G_OBJECT (undo), "exclusive-visible-item",
+                                   (gpointer) item);
+            }
+
+          for (list = ancestry; list; list = g_list_next (list))
+            gimp_image_undo_push_item_visibility (image, NULL, list->data);
+
+          for (list = on; list; list = g_list_next (list))
+            gimp_image_undo_push_item_visibility (image, NULL, list->data);
+
+          for (list = off; list; list = g_list_next (list))
+            gimp_image_undo_push_item_visibility (image, NULL, list->data);
+
+          gimp_image_undo_group_end (image);
+        }
+      else
+        {
+          gimp_undo_refresh_preview (undo, context);
+        }
+
+      for (list = ancestry; list; list = g_list_next (list))
+        gimp_item_set_visible (list->data, TRUE, FALSE);
+
+      if (on)
+        {
+          for (list = on; list; list = g_list_next (list))
+            gimp_item_set_visible (list->data, FALSE, FALSE);
+        }
+      else if (off)
+        {
+          for (list = off; list; list = g_list_next (list))
+            gimp_item_set_visible (list->data, TRUE, FALSE);
+        }
+
+      g_list_free (on);
+      g_list_free (off);
+    }
+
+  g_list_free (ancestry);
+}
+
+void
+gimp_item_toggle_exclusive_linked (GimpItem    *item,
+                                   GimpContext *context)
+{
+  GList *on  = NULL;
+  GList *off = NULL;
+  GList *list;
+
+  g_return_if_fail (GIMP_IS_ITEM (item));
+  g_return_if_fail (gimp_item_is_attached (item));
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  for (list = gimp_item_get_container_iter (item);
+       list;
+       list = g_list_next (list))
+    {
+      GimpItem *other = list->data;
+
+      if (other != item)
+        {
+          if (gimp_item_get_linked (other))
+            on = g_list_prepend (on, other);
+          else
+            off = g_list_prepend (off, other);
+        }
+    }
+
+  if (on || off || ! gimp_item_get_linked (item))
+    {
+      GimpImage *image = gimp_item_get_image (item);
+      GimpUndo  *undo;
+      gboolean   push_undo = TRUE;
+
+      undo = gimp_image_undo_can_compress (image, GIMP_TYPE_UNDO_STACK,
+                                           GIMP_UNDO_GROUP_ITEM_LINKED);
+
+      if (undo && (g_object_get_data (G_OBJECT (undo), "exclusive-linked-item") ==
+                   (gpointer) item))
+        push_undo = FALSE;
+
+      if (push_undo)
+        {
+          if (gimp_image_undo_group_start (image,
+                                           GIMP_UNDO_GROUP_ITEM_LINKED,
+                                           _("Set Item Exclusive Linked")))
+            {
+              undo = gimp_image_undo_can_compress (image, GIMP_TYPE_UNDO_STACK,
+                                                   GIMP_UNDO_GROUP_ITEM_LINKED);
+
+              if (undo)
+                g_object_set_data (G_OBJECT (undo), "exclusive-linked-item",
+                                   (gpointer) item);
+            }
+
+          gimp_image_undo_push_item_linked (image, NULL, item);
+
+          for (list = on; list; list = g_list_next (list))
+            gimp_image_undo_push_item_linked (image, NULL, list->data);
+
+          for (list = off; list; list = g_list_next (list))
+            gimp_image_undo_push_item_linked (image, NULL, list->data);
+
+          gimp_image_undo_group_end (image);
+        }
+      else
+        {
+          gimp_undo_refresh_preview (undo, context);
+        }
+
+      if (off || ! gimp_item_get_linked (item))
+        {
+          gimp_item_set_linked (item, TRUE, FALSE);
+
+          for (list = off; list; list = g_list_next (list))
+            gimp_item_set_linked (list->data, TRUE, FALSE);
+        }
+      else
+        {
+          for (list = on; list; list = g_list_next (list))
+            gimp_item_set_linked (list->data, FALSE, FALSE);
+        }
+
+      g_list_free (on);
+      g_list_free (off);
+    }
+}
+
+
+/*  private functions  */
+
+static GList *
+gimp_item_exclusive_get_ancestry (GimpItem *item)
+{
+  GimpViewable *parent;
+  GList        *ancestry = NULL;
+
+  for (parent = GIMP_VIEWABLE (item);
+       parent;
+       parent = gimp_viewable_get_parent (parent))
+    {
+      ancestry = g_list_prepend (ancestry, parent);
+    }
+
+  return ancestry;
+}
+
+static void
+gimp_item_exclusive_get_lists (GimpItem     *item,
+                               const gchar  *property,
+                               GList       **on,
+                               GList       **off)
+{
+  GimpItemTree *tree;
+  GList        *items;
+  GList        *list;
+
+  *on  = NULL;
+  *off = NULL;
+
+  tree = gimp_item_get_tree (item);
+
+  items = gimp_item_stack_get_item_list (GIMP_ITEM_STACK (tree->container));
+
+  for (list = items; list; list = g_list_next (list))
+    {
+      GimpItem *other = list->data;
+
+      if (other != item)
+        {
+          /* we are only interested in same level items.
+           */
+          if (gimp_viewable_get_parent (GIMP_VIEWABLE (other)) ==
+              gimp_viewable_get_parent (GIMP_VIEWABLE (item)))
+            {
+              gboolean value;
+
+              g_object_get (other, property, &value, NULL);
+
+              if (value)
+                *on = g_list_prepend (*on, other);
+              else
+                *off = g_list_prepend (*off, other);
+            }
+        }
+    }
+
+  g_list_free (items);
+}
diff --git a/app/core/gimpitem-exclusive.h b/app/core/gimpitem-exclusive.h
new file mode 100644
index 0000000..98838c5
--- /dev/null
+++ b/app/core/gimpitem-exclusive.h
@@ -0,0 +1,31 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpitem-exclusive.h
+ * Copyright (C) 2011 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_ITEM_EXCLUSIVE_H__
+#define __GIMP_ITEM_EXCLUSIVE_H__
+
+
+void   gimp_item_toggle_exclusive_visible (GimpItem    *item,
+                                           GimpContext *context);
+void   gimp_item_toggle_exclusive_linked  (GimpItem    *item,
+                                           GimpContext *context);
+
+
+#endif /* __GIMP_ITEM_EXCLUSIVE_H__ */
diff --git a/app/core/gimpitem-linked.c b/app/core/gimpitem-linked.c
new file mode 100644
index 0000000..9c876e3
--- /dev/null
+++ b/app/core/gimpitem-linked.c
@@ -0,0 +1,187 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gimpcontext.h"
+#include "gimpimage.h"
+#include "gimpimage-item-list.h"
+#include "gimpimage-undo.h"
+#include "gimpitem.h"
+#include "gimpitem-linked.h"
+#include "gimplist.h"
+#include "gimpprogress.h"
+
+#include "gimp-intl.h"
+
+
+/*  public functions  */
+
+gboolean
+gimp_item_linked_is_locked (GimpItem *item)
+{
+  GList    *list;
+  GList    *l;
+  gboolean  locked = FALSE;
+
+  g_return_val_if_fail (GIMP_IS_ITEM (item), FALSE);
+  g_return_val_if_fail (gimp_item_get_linked (item) == TRUE, FALSE);
+  g_return_val_if_fail (gimp_item_is_attached (item), FALSE);
+
+  list = gimp_image_item_list_get_list (gimp_item_get_image (item),
+                                        GIMP_ITEM_TYPE_ALL,
+                                        GIMP_ITEM_SET_LINKED);
+
+  list = gimp_image_item_list_filter (list);
+
+  for (l = list; l && ! locked; l = g_list_next (l))
+    {
+      /* We must not use gimp_item_is_position_locked(), especially
+       * since a child implementation may call the current function and
+       * end up in infinite loop.
+       * We are only interested in the value of `lock_position` flag.
+       */
+      if (gimp_item_get_lock_position (l->data))
+        locked = TRUE;
+    }
+
+  g_list_free (list);
+
+  return locked;
+}
+
+void
+gimp_item_linked_translate (GimpItem *item,
+                            gint      offset_x,
+                            gint      offset_y,
+                            gboolean  push_undo)
+{
+  GimpImage *image;
+  GList     *items;
+
+  g_return_if_fail (GIMP_IS_ITEM (item));
+  g_return_if_fail (gimp_item_get_linked (item) == TRUE);
+  g_return_if_fail (gimp_item_is_attached (item));
+
+  image = gimp_item_get_image (item);
+
+  items = gimp_image_item_list_get_list (image,
+                                         GIMP_ITEM_TYPE_ALL,
+                                         GIMP_ITEM_SET_LINKED);
+
+  items = gimp_image_item_list_filter (items);
+
+  gimp_image_item_list_translate (gimp_item_get_image (item), items,
+                                  offset_x, offset_y, push_undo);
+
+  g_list_free (items);
+}
+
+void
+gimp_item_linked_flip (GimpItem            *item,
+                       GimpContext         *context,
+                       GimpOrientationType  flip_type,
+                       gdouble              axis,
+                       gboolean             clip_result)
+{
+  GimpImage *image;
+  GList     *items;
+
+  g_return_if_fail (GIMP_IS_ITEM (item));
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+  g_return_if_fail (gimp_item_get_linked (item) == TRUE);
+  g_return_if_fail (gimp_item_is_attached (item));
+
+  image = gimp_item_get_image (item);
+
+  items = gimp_image_item_list_get_list (image,
+                                         GIMP_ITEM_TYPE_ALL,
+                                         GIMP_ITEM_SET_LINKED);
+  items = gimp_image_item_list_filter (items);
+
+  gimp_image_item_list_flip (image, items, context,
+                             flip_type, axis, clip_result);
+
+  g_list_free (items);
+}
+
+void
+gimp_item_linked_rotate (GimpItem         *item,
+                         GimpContext      *context,
+                         GimpRotationType  rotate_type,
+                         gdouble           center_x,
+                         gdouble           center_y,
+                         gboolean          clip_result)
+{
+  GimpImage *image;
+  GList     *items;
+
+  g_return_if_fail (GIMP_IS_ITEM (item));
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+  g_return_if_fail (gimp_item_get_linked (item) == TRUE);
+  g_return_if_fail (gimp_item_is_attached (item));
+
+  image = gimp_item_get_image (item);
+
+  items = gimp_image_item_list_get_list (image,
+                                         GIMP_ITEM_TYPE_ALL,
+                                         GIMP_ITEM_SET_LINKED);
+  items = gimp_image_item_list_filter (items);
+
+  gimp_image_item_list_rotate (image, items, context,
+                               rotate_type, center_x, center_y, clip_result);
+
+  g_list_free (items);
+}
+
+void
+gimp_item_linked_transform (GimpItem               *item,
+                            GimpContext            *context,
+                            const GimpMatrix3      *matrix,
+                            GimpTransformDirection  direction,
+                            GimpInterpolationType   interpolation_type,
+                            GimpTransformResize     clip_result,
+                            GimpProgress           *progress)
+{
+  GimpImage *image;
+  GList     *items;
+
+  g_return_if_fail (GIMP_IS_ITEM (item));
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+  g_return_if_fail (gimp_item_get_linked (item) == TRUE);
+  g_return_if_fail (gimp_item_is_attached (item));
+  g_return_if_fail (progress == NULL || GIMP_IS_PROGRESS (progress));
+
+  image = gimp_item_get_image (item);
+
+  items = gimp_image_item_list_get_list (image,
+                                         GIMP_ITEM_TYPE_ALL,
+                                         GIMP_ITEM_SET_LINKED);
+  items = gimp_image_item_list_filter (items);
+
+  gimp_image_item_list_transform (image, items, context,
+                                  matrix, direction,
+                                  interpolation_type,
+                                  clip_result, progress);
+
+  g_list_free (items);
+}
diff --git a/app/core/gimpitem-linked.h b/app/core/gimpitem-linked.h
new file mode 100644
index 0000000..c82d85a
--- /dev/null
+++ b/app/core/gimpitem-linked.h
@@ -0,0 +1,48 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_ITEM_LINKED_H__
+#define __GIMP_ITEM_LINKED_H__
+
+
+gboolean gimp_item_linked_is_locked (GimpItem               *item);
+
+void     gimp_item_linked_translate (GimpItem               *item,
+                                     gint                    offset_x,
+                                     gint                    offset_y,
+                                     gboolean                push_undo);
+void     gimp_item_linked_flip      (GimpItem               *item,
+                                     GimpContext            *context,
+                                     GimpOrientationType     flip_type,
+                                     gdouble                 axis,
+                                     gboolean                clip_result);
+void     gimp_item_linked_rotate    (GimpItem               *item,
+                                     GimpContext            *context,
+                                     GimpRotationType        rotate_type,
+                                     gdouble                 center_x,
+                                     gdouble                 center_y,
+                                     gboolean                clip_result);
+void     gimp_item_linked_transform (GimpItem               *item,
+                                     GimpContext            *context,
+                                     const GimpMatrix3      *matrix,
+                                     GimpTransformDirection  direction,
+                                     GimpInterpolationType   interpolation_type,
+                                     GimpTransformResize     clip_result,
+                                     GimpProgress           *progress);
+
+
+#endif /* __GIMP_ITEM_LINKED_H__ */
diff --git a/app/core/gimpitem-preview.c b/app/core/gimpitem-preview.c
new file mode 100644
index 0000000..f24017b
--- /dev/null
+++ b/app/core/gimpitem-preview.c
@@ -0,0 +1,133 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpmath/gimpmath.h"
+
+#include "core-types.h"
+
+#include "config/gimpcoreconfig.h"
+
+#include "gimp.h"
+#include "gimpimage.h"
+#include "gimpitem.h"
+#include "gimpitem-preview.h"
+
+
+/*  public functions  */
+
+void
+gimp_item_get_preview_size (GimpViewable *viewable,
+                            gint          size,
+                            gboolean      is_popup,
+                            gboolean      dot_for_dot,
+                            gint         *width,
+                            gint         *height)
+{
+  GimpItem  *item  = GIMP_ITEM (viewable);
+  GimpImage *image = gimp_item_get_image (item);
+
+  if (image && ! image->gimp->config->layer_previews && ! is_popup)
+    {
+      *width  = size;
+      *height = size;
+      return;
+    }
+
+  if (image && ! is_popup)
+    {
+      gdouble xres;
+      gdouble yres;
+
+      gimp_image_get_resolution (image, &xres, &yres);
+
+      gimp_viewable_calc_preview_size (gimp_image_get_width  (image),
+                                       gimp_image_get_height (image),
+                                       size,
+                                       size,
+                                       dot_for_dot,
+                                       xres,
+                                       yres,
+                                       width,
+                                       height,
+                                       NULL);
+    }
+  else
+    {
+      gimp_viewable_calc_preview_size (gimp_item_get_width  (item),
+                                       gimp_item_get_height (item),
+                                       size,
+                                       size,
+                                       dot_for_dot, 1.0, 1.0,
+                                       width,
+                                       height,
+                                       NULL);
+    }
+}
+
+gboolean
+gimp_item_get_popup_size (GimpViewable *viewable,
+                          gint          width,
+                          gint          height,
+                          gboolean      dot_for_dot,
+                          gint         *popup_width,
+                          gint         *popup_height)
+{
+  GimpItem  *item  = GIMP_ITEM (viewable);
+  GimpImage *image = gimp_item_get_image (item);
+
+  if (image && ! image->gimp->config->layer_previews)
+    return FALSE;
+
+  if (gimp_item_get_width  (item) > width ||
+      gimp_item_get_height (item) > height)
+    {
+      gboolean scaling_up;
+      gdouble  xres = 1.0;
+      gdouble  yres = 1.0;
+
+      if (image)
+        gimp_image_get_resolution (image, &xres, &yres);
+
+      gimp_viewable_calc_preview_size (gimp_item_get_width  (item),
+                                       gimp_item_get_height (item),
+                                       width  * 2,
+                                       height * 2,
+                                       dot_for_dot,
+                                       xres,
+                                       yres,
+                                       popup_width,
+                                       popup_height,
+                                       &scaling_up);
+
+      if (scaling_up)
+        {
+          *popup_width  = gimp_item_get_width  (item);
+          *popup_height = gimp_item_get_height (item);
+        }
+
+      return TRUE;
+    }
+
+  return FALSE;
+}
diff --git a/app/core/gimpitem-preview.h b/app/core/gimpitem-preview.h
new file mode 100644
index 0000000..6bfed24
--- /dev/null
+++ b/app/core/gimpitem-preview.h
@@ -0,0 +1,40 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_ITEM__PREVIEW_H__
+#define __GIMP_ITEM__PREVIEW_H__
+
+
+/*
+ *  virtual functions of GimpItem -- don't call directly
+ */
+
+void      gimp_item_get_preview_size (GimpViewable *viewable,
+                                      gint          size,
+                                      gboolean      is_popup,
+                                      gboolean      dot_for_dot,
+                                      gint         *width,
+                                      gint         *height);
+gboolean  gimp_item_get_popup_size   (GimpViewable *viewable,
+                                      gint          width,
+                                      gint          height,
+                                      gboolean      dot_for_dot,
+                                      gint         *popup_width,
+                                      gint         *popup_height);
+
+
+#endif /* __GIMP_ITEM__PREVIEW_H__ */
diff --git a/app/core/gimpitem.c b/app/core/gimpitem.c
new file mode 100644
index 0000000..c0f732c
--- /dev/null
+++ b/app/core/gimpitem.c
@@ -0,0 +1,2689 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpmath/gimpmath.h"
+
+#include "core-types.h"
+
+#include "gimp.h"
+#include "gimp-parasites.h"
+#include "gimpchannel.h"
+#include "gimpcontainer.h"
+#include "gimpidtable.h"
+#include "gimpimage.h"
+#include "gimpimage-undo.h"
+#include "gimpimage-undo-push.h"
+#include "gimpitem.h"
+#include "gimpitem-linked.h"
+#include "gimpitem-preview.h"
+#include "gimpitemtree.h"
+#include "gimplist.h"
+#include "gimpmarshal.h"
+#include "gimpparasitelist.h"
+#include "gimpprogress.h"
+#include "gimpstrokeoptions.h"
+
+#include "paint/gimppaintoptions.h"
+
+#include "gimp-intl.h"
+
+
+enum
+{
+  REMOVED,
+  VISIBILITY_CHANGED,
+  LINKED_CHANGED,
+  COLOR_TAG_CHANGED,
+  LOCK_CONTENT_CHANGED,
+  LOCK_POSITION_CHANGED,
+  LAST_SIGNAL
+};
+
+enum
+{
+  PROP_0,
+  PROP_IMAGE,
+  PROP_ID,
+  PROP_WIDTH,
+  PROP_HEIGHT,
+  PROP_OFFSET_X,
+  PROP_OFFSET_Y,
+  PROP_VISIBLE,
+  PROP_LINKED,
+  PROP_COLOR_TAG,
+  PROP_LOCK_CONTENT,
+  PROP_LOCK_POSITION
+};
+
+
+typedef struct _GimpItemPrivate GimpItemPrivate;
+
+struct _GimpItemPrivate
+{
+  gint              ID;                          /*  provides a unique ID        */
+  guint32           tattoo;                      /*  provides a permanent ID     */
+
+  GimpImage        *image;                       /*  item owner                  */
+
+  GimpParasiteList *parasites;                   /*  Plug-in parasite data       */
+
+  gint              width, height;               /*  size in pixels              */
+  gint              offset_x, offset_y;          /*  pixel offset in image       */
+
+  guint             visible                : 1;  /*  item visibility             */
+  guint             bind_visible_to_active : 1;  /*  visibility bound to active  */
+
+  guint             linked                 : 1;  /*  control linkage             */
+  guint             lock_content           : 1;  /*  content editability         */
+  guint             lock_position          : 1;  /*  content movability          */
+
+  guint             removed                : 1;  /*  removed from the image?     */
+
+  GimpColorTag      color_tag;                   /*  color tag                   */
+
+  GList            *offset_nodes;                /*  offset nodes to manage      */
+};
+
+#define GET_PRIVATE(item) ((GimpItemPrivate *) gimp_item_get_instance_private ((GimpItem *) (item)))
+
+
+/*  local function prototypes  */
+
+static void       gimp_item_constructed             (GObject        *object);
+static void       gimp_item_finalize                (GObject        *object);
+static void       gimp_item_set_property            (GObject        *object,
+                                                     guint           property_id,
+                                                     const GValue   *value,
+                                                     GParamSpec     *pspec);
+static void       gimp_item_get_property            (GObject        *object,
+                                                     guint           property_id,
+                                                     GValue         *value,
+                                                     GParamSpec     *pspec);
+
+static gint64     gimp_item_get_memsize             (GimpObject     *object,
+                                                     gint64         *gui_size);
+
+static gboolean   gimp_item_real_is_content_locked  (GimpItem       *item);
+static gboolean   gimp_item_real_is_position_locked (GimpItem       *item);
+static gboolean   gimp_item_real_bounds             (GimpItem       *item,
+                                                     gdouble        *x,
+                                                     gdouble        *y,
+                                                     gdouble        *width,
+                                                     gdouble        *height);
+static GimpItem * gimp_item_real_duplicate          (GimpItem       *item,
+                                                     GType           new_type);
+static void       gimp_item_real_convert            (GimpItem       *item,
+                                                     GimpImage      *dest_image,
+                                                     GType           old_type);
+static gboolean   gimp_item_real_rename             (GimpItem       *item,
+                                                     const gchar    *new_name,
+                                                     const gchar    *undo_desc,
+                                                     GError        **error);
+static void       gimp_item_real_start_transform    (GimpItem       *item,
+                                                     gboolean        push_undo);
+static void       gimp_item_real_end_transform      (GimpItem       *item,
+                                                     gboolean        push_undo);
+static void       gimp_item_real_translate          (GimpItem       *item,
+                                                     gdouble         offset_x,
+                                                     gdouble         offset_y,
+                                                     gboolean        push_undo);
+static void       gimp_item_real_scale              (GimpItem       *item,
+                                                     gint            new_width,
+                                                     gint            new_height,
+                                                     gint            new_offset_x,
+                                                     gint            new_offset_y,
+                                                     GimpInterpolationType interpolation,
+                                                     GimpProgress   *progress);
+static void       gimp_item_real_resize             (GimpItem       *item,
+                                                     GimpContext    *context,
+                                                     GimpFillType    fill_type,
+                                                     gint            new_width,
+                                                     gint            new_height,
+                                                     gint            offset_x,
+                                                     gint            offset_y);
+static GimpTransformResize
+                  gimp_item_real_get_clip           (GimpItem       *item,
+                                                     GimpTransformResize clip_result);
+
+
+
+G_DEFINE_TYPE_WITH_PRIVATE (GimpItem, gimp_item, GIMP_TYPE_FILTER)
+
+#define parent_class gimp_item_parent_class
+
+static guint gimp_item_signals[LAST_SIGNAL] = { 0 };
+
+
+static void
+gimp_item_class_init (GimpItemClass *klass)
+{
+  GObjectClass      *object_class      = G_OBJECT_CLASS (klass);
+  GimpObjectClass   *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+  GimpViewableClass *viewable_class    = GIMP_VIEWABLE_CLASS (klass);
+
+  gimp_item_signals[REMOVED] =
+    g_signal_new ("removed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpItemClass, removed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  gimp_item_signals[VISIBILITY_CHANGED] =
+    g_signal_new ("visibility-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpItemClass, visibility_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  gimp_item_signals[LINKED_CHANGED] =
+    g_signal_new ("linked-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpItemClass, linked_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  gimp_item_signals[COLOR_TAG_CHANGED] =
+    g_signal_new ("color-tag-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpItemClass, color_tag_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  gimp_item_signals[LOCK_CONTENT_CHANGED] =
+    g_signal_new ("lock-content-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpItemClass, lock_content_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  gimp_item_signals[LOCK_POSITION_CHANGED] =
+    g_signal_new ("lock-position-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpItemClass, lock_position_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  object_class->constructed        = gimp_item_constructed;
+  object_class->finalize           = gimp_item_finalize;
+  object_class->set_property       = gimp_item_set_property;
+  object_class->get_property       = gimp_item_get_property;
+
+  gimp_object_class->get_memsize   = gimp_item_get_memsize;
+
+  viewable_class->name_editable    = TRUE;
+  viewable_class->get_preview_size = gimp_item_get_preview_size;
+  viewable_class->get_popup_size   = gimp_item_get_popup_size;
+
+  klass->removed                   = NULL;
+  klass->visibility_changed        = NULL;
+  klass->linked_changed            = NULL;
+  klass->color_tag_changed         = NULL;
+  klass->lock_content_changed      = NULL;
+  klass->lock_position_changed     = NULL;
+
+  klass->unset_removed             = NULL;
+  klass->is_attached               = NULL;
+  klass->is_content_locked         = gimp_item_real_is_content_locked;
+  klass->is_position_locked        = gimp_item_real_is_position_locked;
+  klass->get_tree                  = NULL;
+  klass->bounds                    = gimp_item_real_bounds;
+  klass->duplicate                 = gimp_item_real_duplicate;
+  klass->convert                   = gimp_item_real_convert;
+  klass->rename                    = gimp_item_real_rename;
+  klass->start_move                = NULL;
+  klass->end_move                  = NULL;
+  klass->start_transform           = gimp_item_real_start_transform;
+  klass->end_transform             = gimp_item_real_end_transform;
+  klass->translate                 = gimp_item_real_translate;
+  klass->scale                     = gimp_item_real_scale;
+  klass->resize                    = gimp_item_real_resize;
+  klass->flip                      = NULL;
+  klass->rotate                    = NULL;
+  klass->transform                 = NULL;
+  klass->get_clip                  = gimp_item_real_get_clip;
+  klass->fill                      = NULL;
+  klass->stroke                    = NULL;
+  klass->to_selection              = NULL;
+
+  klass->default_name              = NULL;
+  klass->rename_desc               = NULL;
+  klass->translate_desc            = NULL;
+  klass->scale_desc                = NULL;
+  klass->resize_desc               = NULL;
+  klass->flip_desc                 = NULL;
+  klass->rotate_desc               = NULL;
+  klass->transform_desc            = NULL;
+  klass->fill_desc                 = NULL;
+  klass->stroke_desc               = NULL;
+
+  g_object_class_install_property (object_class, PROP_IMAGE,
+                                   g_param_spec_object ("image", NULL, NULL,
+                                                        GIMP_TYPE_IMAGE,
+                                                        GIMP_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT));
+  g_object_class_install_property (object_class, PROP_ID,
+                                   g_param_spec_int ("id", NULL, NULL,
+                                                     0, G_MAXINT, 0,
+                                                     GIMP_PARAM_READABLE));
+
+  g_object_class_install_property (object_class, PROP_WIDTH,
+                                   g_param_spec_int ("width", NULL, NULL,
+                                                     1, GIMP_MAX_IMAGE_SIZE, 1,
+                                                     GIMP_PARAM_READABLE));
+
+  g_object_class_install_property (object_class, PROP_HEIGHT,
+                                   g_param_spec_int ("height", NULL, NULL,
+                                                     1, GIMP_MAX_IMAGE_SIZE, 1,
+                                                     GIMP_PARAM_READABLE));
+
+  g_object_class_install_property (object_class, PROP_OFFSET_X,
+                                   g_param_spec_int ("offset-x", NULL, NULL,
+                                                     -GIMP_MAX_IMAGE_SIZE,
+                                                     GIMP_MAX_IMAGE_SIZE, 0,
+                                                     GIMP_PARAM_READABLE));
+
+  g_object_class_install_property (object_class, PROP_OFFSET_Y,
+                                   g_param_spec_int ("offset-y", NULL, NULL,
+                                                     -GIMP_MAX_IMAGE_SIZE,
+                                                     GIMP_MAX_IMAGE_SIZE, 0,
+                                                     GIMP_PARAM_READABLE));
+
+  g_object_class_install_property (object_class, PROP_VISIBLE,
+                                   g_param_spec_boolean ("visible", NULL, NULL,
+                                                         TRUE,
+                                                         GIMP_PARAM_READABLE));
+
+  g_object_class_install_property (object_class, PROP_LINKED,
+                                   g_param_spec_boolean ("linked", NULL, NULL,
+                                                         FALSE,
+                                                         GIMP_PARAM_READABLE));
+
+  g_object_class_install_property (object_class, PROP_COLOR_TAG,
+                                   g_param_spec_enum ("color-tag", NULL, NULL,
+                                                      GIMP_TYPE_COLOR_TAG,
+                                                      GIMP_COLOR_TAG_NONE,
+                                                      GIMP_PARAM_READABLE));
+
+  g_object_class_install_property (object_class, PROP_LOCK_CONTENT,
+                                   g_param_spec_boolean ("lock-content",
+                                                         NULL, NULL,
+                                                         FALSE,
+                                                         GIMP_PARAM_READABLE));
+
+  g_object_class_install_property (object_class, PROP_LOCK_POSITION,
+                                   g_param_spec_boolean ("lock-position",
+                                                         NULL, NULL,
+                                                         FALSE,
+                                                         GIMP_PARAM_READABLE));
+}
+
+static void
+gimp_item_init (GimpItem *item)
+{
+  GimpItemPrivate *private = GET_PRIVATE (item);
+
+  g_object_force_floating (G_OBJECT (item));
+
+  private->parasites              = gimp_parasite_list_new ();
+  private->visible                = TRUE;
+  private->bind_visible_to_active = TRUE;
+}
+
+static void
+gimp_item_constructed (GObject *object)
+{
+  GimpItemPrivate *private = GET_PRIVATE (object);
+
+  G_OBJECT_CLASS (parent_class)->constructed (object);
+
+  gimp_assert (GIMP_IS_IMAGE (private->image));
+  gimp_assert (private->ID != 0);
+}
+
+static void
+gimp_item_finalize (GObject *object)
+{
+  GimpItemPrivate *private = GET_PRIVATE (object);
+
+  if (private->offset_nodes)
+    {
+      g_list_free_full (private->offset_nodes,
+                        (GDestroyNotify) g_object_unref);
+      private->offset_nodes = NULL;
+    }
+
+  if (private->image && private->image->gimp)
+    {
+      gimp_id_table_remove (private->image->gimp->item_table, private->ID);
+      private->image = NULL;
+    }
+
+  g_clear_object (&private->parasites);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gimp_item_set_property (GObject      *object,
+                        guint         property_id,
+                        const GValue *value,
+                        GParamSpec   *pspec)
+{
+  GimpItem *item = GIMP_ITEM (object);
+
+  switch (property_id)
+    {
+    case PROP_IMAGE:
+      gimp_item_set_image (item, g_value_get_object (value));
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_item_get_property (GObject    *object,
+                        guint       property_id,
+                        GValue     *value,
+                        GParamSpec *pspec)
+{
+  GimpItemPrivate *private = GET_PRIVATE (object);
+
+  switch (property_id)
+    {
+    case PROP_IMAGE:
+      g_value_set_object (value, private->image);
+      break;
+    case PROP_ID:
+      g_value_set_int (value, private->ID);
+      break;
+    case PROP_WIDTH:
+      g_value_set_int (value, private->width);
+      break;
+    case PROP_HEIGHT:
+      g_value_set_int (value, private->height);
+      break;
+    case PROP_OFFSET_X:
+      g_value_set_int (value, private->offset_x);
+      break;
+    case PROP_OFFSET_Y:
+      g_value_set_int (value, private->offset_y);
+      break;
+    case PROP_VISIBLE:
+      g_value_set_boolean (value, private->visible);
+      break;
+    case PROP_LINKED:
+      g_value_set_boolean (value, private->linked);
+      break;
+    case PROP_COLOR_TAG:
+      g_value_set_enum (value, private->color_tag);
+      break;
+    case PROP_LOCK_CONTENT:
+      g_value_set_boolean (value, private->lock_content);
+      break;
+    case PROP_LOCK_POSITION:
+      g_value_set_boolean (value, private->lock_position);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static gint64
+gimp_item_get_memsize (GimpObject *object,
+                       gint64     *gui_size)
+{
+  GimpItemPrivate *private = GET_PRIVATE (object);
+  gint64           memsize = 0;
+
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (private->parasites),
+                                      gui_size);
+
+  return memsize + GIMP_OBJECT_CLASS (parent_class)->get_memsize (object,
+                                                                  gui_size);
+}
+
+static gboolean
+gimp_item_real_is_content_locked (GimpItem *item)
+{
+  GimpItem *parent = gimp_item_get_parent (item);
+
+  if (parent && gimp_item_is_content_locked (parent))
+    return TRUE;
+
+  return GET_PRIVATE (item)->lock_content;
+}
+
+static gboolean
+gimp_item_real_is_position_locked (GimpItem *item)
+{
+  if (gimp_item_get_linked (item))
+    if (gimp_item_linked_is_locked (item))
+      return TRUE;
+
+  return GET_PRIVATE (item)->lock_position;
+}
+
+static gboolean
+gimp_item_real_bounds (GimpItem *item,
+                       gdouble  *x,
+                       gdouble  *y,
+                       gdouble  *width,
+                       gdouble  *height)
+{
+  GimpItemPrivate *private = GET_PRIVATE (item);
+
+  *x      = 0;
+  *y      = 0;
+  *width  = private->width;
+  *height = private->height;
+
+  return TRUE;
+}
+
+static GimpItem *
+gimp_item_real_duplicate (GimpItem *item,
+                          GType     new_type)
+{
+  GimpItemPrivate *private;
+  GimpItem        *new_item;
+  gchar           *new_name;
+
+  g_return_val_if_fail (GIMP_IS_ITEM (item), NULL);
+
+  private = GET_PRIVATE (item);
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (private->image), NULL);
+  g_return_val_if_fail (g_type_is_a (new_type, GIMP_TYPE_ITEM), NULL);
+
+  /*  formulate the new name  */
+  {
+    const gchar *name;
+    gint         len;
+
+    name = gimp_object_get_name (item);
+
+    g_return_val_if_fail (name != NULL, NULL);
+
+    len = strlen (_("copy"));
+
+    if ((strlen (name) >= len &&
+         strcmp (&name[strlen (name) - len], _("copy")) == 0) ||
+        g_regex_match_simple ("#([0-9]+)\\s*$", name, 0, 0))
+      {
+        /* don't have redundant "copy"s */
+        new_name = g_strdup (name);
+      }
+    else
+      {
+        new_name = g_strdup_printf (_("%s copy"), name);
+      }
+  }
+
+  new_item = gimp_item_new (new_type,
+                            gimp_item_get_image (item), new_name,
+                            private->offset_x, private->offset_y,
+                            gimp_item_get_width  (item),
+                            gimp_item_get_height (item));
+
+  g_free (new_name);
+
+  gimp_viewable_set_expanded (GIMP_VIEWABLE (new_item),
+                              gimp_viewable_get_expanded (GIMP_VIEWABLE (item)));
+
+  g_object_unref (GET_PRIVATE (new_item)->parasites);
+  GET_PRIVATE (new_item)->parasites = gimp_parasite_list_copy (private->parasites);
+
+  gimp_item_set_visible   (new_item, gimp_item_get_visible   (item), FALSE);
+  gimp_item_set_linked    (new_item, gimp_item_get_linked    (item), FALSE);
+  gimp_item_set_color_tag (new_item, gimp_item_get_color_tag (item), FALSE);
+
+  if (gimp_item_can_lock_content (new_item))
+    gimp_item_set_lock_content (new_item, gimp_item_get_lock_content (item),
+                                FALSE);
+
+  if (gimp_item_can_lock_position (new_item))
+    gimp_item_set_lock_position (new_item, gimp_item_get_lock_position (item),
+                                 FALSE);
+
+  return new_item;
+}
+
+static void
+gimp_item_real_convert (GimpItem  *item,
+                        GimpImage *dest_image,
+                        GType      old_type)
+{
+  gimp_item_set_image (item, dest_image);
+}
+
+static gboolean
+gimp_item_real_rename (GimpItem     *item,
+                       const gchar  *new_name,
+                       const gchar  *undo_desc,
+                       GError      **error)
+{
+  if (gimp_item_is_attached (item))
+    gimp_item_tree_rename_item (gimp_item_get_tree (item), item,
+                                new_name, TRUE, undo_desc);
+  else
+    gimp_object_set_name (GIMP_OBJECT (item), new_name);
+
+  return TRUE;
+}
+
+static void
+gimp_item_real_translate (GimpItem *item,
+                          gdouble   offset_x,
+                          gdouble   offset_y,
+                          gboolean  push_undo)
+{
+  GimpItemPrivate *private = GET_PRIVATE (item);
+
+  gimp_item_set_offset (item,
+                        private->offset_x + SIGNED_ROUND (offset_x),
+                        private->offset_y + SIGNED_ROUND (offset_y));
+}
+
+static void
+gimp_item_real_start_transform (GimpItem *item,
+                                gboolean  push_undo)
+{
+  gimp_item_start_move (item, push_undo);
+}
+
+static void
+gimp_item_real_end_transform (GimpItem *item,
+                                gboolean  push_undo)
+{
+  gimp_item_end_move (item, push_undo);
+}
+
+static void
+gimp_item_real_scale (GimpItem              *item,
+                      gint                   new_width,
+                      gint                   new_height,
+                      gint                   new_offset_x,
+                      gint                   new_offset_y,
+                      GimpInterpolationType  interpolation,
+                      GimpProgress          *progress)
+{
+  GimpItemPrivate *private = GET_PRIVATE (item);
+
+  if (private->width != new_width)
+    {
+      private->width = new_width;
+      g_object_notify (G_OBJECT (item), "width");
+    }
+
+  if (private->height != new_height)
+    {
+      private->height = new_height;
+      g_object_notify (G_OBJECT (item), "height");
+    }
+
+  gimp_item_set_offset (item, new_offset_x, new_offset_y);
+}
+
+static void
+gimp_item_real_resize (GimpItem     *item,
+                       GimpContext  *context,
+                       GimpFillType  fill_type,
+                       gint          new_width,
+                       gint          new_height,
+                       gint          offset_x,
+                       gint          offset_y)
+{
+  GimpItemPrivate *private = GET_PRIVATE (item);
+
+  if (private->width != new_width)
+    {
+      private->width = new_width;
+      g_object_notify (G_OBJECT (item), "width");
+    }
+
+  if (private->height != new_height)
+    {
+      private->height = new_height;
+      g_object_notify (G_OBJECT (item), "height");
+    }
+
+  gimp_item_set_offset (item,
+                        private->offset_x - offset_x,
+                        private->offset_y - offset_y);
+}
+
+static GimpTransformResize
+gimp_item_real_get_clip (GimpItem            *item,
+                         GimpTransformResize  clip_result)
+{
+  if (gimp_item_get_lock_position (item))
+    return GIMP_TRANSFORM_RESIZE_CLIP;
+  else
+    return clip_result;
+}
+
+
+/*  public functions  */
+
+/**
+ * gimp_item_new:
+ * @type:     The new item's type.
+ * @image:    The new item's #GimpImage.
+ * @name:     The name to assign the item.
+ * @offset_x: The X offset to assign the item.
+ * @offset_y: The Y offset to assign the item.
+ * @width:    The width to assign the item.
+ * @height:   The height to assign the item.
+ *
+ * Return value: The newly created item.
+ */
+GimpItem *
+gimp_item_new (GType        type,
+               GimpImage   *image,
+               const gchar *name,
+               gint         offset_x,
+               gint         offset_y,
+               gint         width,
+               gint         height)
+{
+  GimpItem        *item;
+  GimpItemPrivate *private;
+
+  g_return_val_if_fail (g_type_is_a (type, GIMP_TYPE_ITEM), NULL);
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (width > 0 && height > 0, NULL);
+
+  item = g_object_new (type,
+                       "image", image,
+                       NULL);
+
+  private = GET_PRIVATE (item);
+
+  private->width  = width;
+  private->height = height;
+  gimp_item_set_offset (item, offset_x, offset_y);
+
+  if (name && strlen (name))
+    gimp_object_set_name (GIMP_OBJECT (item), name);
+  else
+    gimp_object_set_static_name (GIMP_OBJECT (item),
+                                 GIMP_ITEM_GET_CLASS (item)->default_name);
+
+  return item;
+}
+
+/**
+ * gimp_item_remove:
+ * @item: the #GimpItem to remove.
+ *
+ * This function sets the 'removed' flag on @item to #TRUE, and emits
+ * a 'removed' signal on the item.
+ */
+void
+gimp_item_removed (GimpItem *item)
+{
+  GimpContainer *children;
+
+  g_return_if_fail (GIMP_IS_ITEM (item));
+
+  GET_PRIVATE (item)->removed = TRUE;
+
+  children = gimp_viewable_get_children (GIMP_VIEWABLE (item));
+
+  if (children)
+    gimp_container_foreach (children, (GFunc) gimp_item_removed, NULL);
+
+  g_signal_emit (item, gimp_item_signals[REMOVED], 0);
+}
+
+/**
+ * gimp_item_is_removed:
+ * @item: the #GimpItem to check.
+ *
+ * Returns: %TRUE if the 'removed' flag is set for @item, %FALSE otherwise.
+ */
+gboolean
+gimp_item_is_removed (GimpItem *item)
+{
+  g_return_val_if_fail (GIMP_IS_ITEM (item), FALSE);
+
+  return GET_PRIVATE (item)->removed;
+}
+
+/**
+ * gimp_item_unset_removed:
+ * @item: a #GimpItem which was on the undo stack
+ *
+ * Unsets an item's "removed" state. This function is called when an
+ * item was on the undo stack and is added back to its parent
+ * container during and undo or redo. It must never be called from
+ * anywhere else.
+ **/
+void
+gimp_item_unset_removed (GimpItem *item)
+{
+  GimpContainer *children;
+
+  g_return_if_fail (GIMP_IS_ITEM (item));
+  g_return_if_fail (gimp_item_is_removed (item));
+
+  GET_PRIVATE (item)->removed = FALSE;
+
+  children = gimp_viewable_get_children (GIMP_VIEWABLE (item));
+
+  if (children)
+    gimp_container_foreach (children, (GFunc) gimp_item_unset_removed, NULL);
+
+  if (GIMP_ITEM_GET_CLASS (item)->unset_removed)
+    GIMP_ITEM_GET_CLASS (item)->unset_removed (item);
+}
+
+/**
+ * gimp_item_is_attached:
+ * @item: The #GimpItem to check.
+ *
+ * Returns: %TRUE if the item is attached to an image, %FALSE otherwise.
+ */
+gboolean
+gimp_item_is_attached (GimpItem *item)
+{
+  GimpItem *parent;
+
+  g_return_val_if_fail (GIMP_IS_ITEM (item), FALSE);
+
+  parent = gimp_item_get_parent (item);
+
+  if (parent)
+    return gimp_item_is_attached (parent);
+
+  return GIMP_ITEM_GET_CLASS (item)->is_attached (item);
+}
+
+GimpItem *
+gimp_item_get_parent (GimpItem *item)
+{
+  g_return_val_if_fail (GIMP_IS_ITEM (item), NULL);
+
+  return GIMP_ITEM (gimp_viewable_get_parent (GIMP_VIEWABLE (item)));
+}
+
+GimpItemTree *
+gimp_item_get_tree (GimpItem *item)
+{
+  g_return_val_if_fail (GIMP_IS_ITEM (item), NULL);
+
+  if (GIMP_ITEM_GET_CLASS (item)->get_tree)
+    return GIMP_ITEM_GET_CLASS (item)->get_tree (item);
+
+  return NULL;
+}
+
+GimpContainer *
+gimp_item_get_container (GimpItem *item)
+{
+  GimpItem     *parent;
+  GimpItemTree *tree;
+
+  g_return_val_if_fail (GIMP_IS_ITEM (item), NULL);
+
+  parent = gimp_item_get_parent (item);
+
+  if (parent)
+    return gimp_viewable_get_children (GIMP_VIEWABLE (parent));
+
+  tree = gimp_item_get_tree (item);
+
+  if (tree)
+    return tree->container;
+
+  return NULL;
+}
+
+GList *
+gimp_item_get_container_iter (GimpItem *item)
+{
+  GimpContainer *container;
+
+  g_return_val_if_fail (GIMP_IS_ITEM (item), NULL);
+
+  container = gimp_item_get_container (item);
+
+  if (container)
+    return GIMP_LIST (container)->queue->head;
+
+  return NULL;
+}
+
+gint
+gimp_item_get_index (GimpItem *item)
+{
+  GimpContainer *container;
+
+  g_return_val_if_fail (GIMP_IS_ITEM (item), -1);
+
+  container = gimp_item_get_container (item);
+
+  if (container)
+    return gimp_container_get_child_index (container, GIMP_OBJECT (item));
+
+  return -1;
+}
+
+GList *
+gimp_item_get_path (GimpItem *item)
+{
+  GimpContainer *container;
+  GList         *path = NULL;
+
+  g_return_val_if_fail (GIMP_IS_ITEM (item), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (item), NULL);
+
+  container = gimp_item_get_container (item);
+
+  while (container)
+    {
+      guint32 index = gimp_container_get_child_index (container,
+                                                      GIMP_OBJECT (item));
+
+      path = g_list_prepend (path, GUINT_TO_POINTER (index));
+
+      item = gimp_item_get_parent (item);
+
+      if (item)
+        container = gimp_item_get_container (item);
+      else
+        container = NULL;
+    }
+
+  return path;
+}
+
+gboolean
+gimp_item_bounds (GimpItem *item,
+                  gint     *x,
+                  gint     *y,
+                  gint     *width,
+                  gint     *height)
+{
+  gdouble  tmp_x, tmp_y, tmp_width, tmp_height;
+  gboolean retval;
+
+  g_return_val_if_fail (GIMP_IS_ITEM (item), FALSE);
+
+  retval = GIMP_ITEM_GET_CLASS (item)->bounds (item,
+                                               &tmp_x, &tmp_y,
+                                               &tmp_width, &tmp_height);
+
+  if (x)      *x      = floor (tmp_x);
+  if (y)      *y      = floor (tmp_y);
+  if (width)  *width  = ceil (tmp_x + tmp_width)  - floor (tmp_x);
+  if (height) *height = ceil (tmp_y + tmp_height) - floor (tmp_y);
+
+  return retval;
+}
+
+gboolean
+gimp_item_bounds_f (GimpItem *item,
+                    gdouble  *x,
+                    gdouble  *y,
+                    gdouble  *width,
+                    gdouble  *height)
+{
+  gdouble  tmp_x, tmp_y, tmp_width, tmp_height;
+  gboolean retval;
+
+  g_return_val_if_fail (GIMP_IS_ITEM (item), FALSE);
+
+  retval = GIMP_ITEM_GET_CLASS (item)->bounds (item,
+                                               &tmp_x, &tmp_y,
+                                               &tmp_width, &tmp_height);
+
+  if (x)      *x      = tmp_x;
+  if (y)      *y      = tmp_y;
+  if (width)  *width  = tmp_width;
+  if (height) *height = tmp_height;
+
+  return retval;
+}
+
+/**
+ * gimp_item_duplicate:
+ * @item:     The #GimpItem to duplicate.
+ * @new_type: The type to make the new item.
+ *
+ * Returns: the newly created item.
+ */
+GimpItem *
+gimp_item_duplicate (GimpItem *item,
+                     GType     new_type)
+{
+  GimpItemPrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_ITEM (item), NULL);
+
+  private = GET_PRIVATE (item);
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (private->image), NULL);
+  g_return_val_if_fail (g_type_is_a (new_type, GIMP_TYPE_ITEM), NULL);
+
+  return GIMP_ITEM_GET_CLASS (item)->duplicate (item, new_type);
+}
+
+/**
+ * gimp_item_convert:
+ * @item:       The #GimpItem to convert.
+ * @dest_image: The #GimpImage in which to place the converted item.
+ * @new_type:   The type to convert the item to.
+ *
+ * Returns: the new item that results from the conversion.
+ */
+GimpItem *
+gimp_item_convert (GimpItem  *item,
+                   GimpImage *dest_image,
+                   GType      new_type)
+{
+  GimpItem *new_item;
+  GType     old_type;
+
+  g_return_val_if_fail (GIMP_IS_ITEM (item), NULL);
+  g_return_val_if_fail (GIMP_IS_IMAGE (GET_PRIVATE (item)->image), NULL);
+  g_return_val_if_fail (GIMP_IS_IMAGE (dest_image), NULL);
+  g_return_val_if_fail (g_type_is_a (new_type, GIMP_TYPE_ITEM), NULL);
+
+  old_type = G_TYPE_FROM_INSTANCE (item);
+
+  new_item = gimp_item_duplicate (item, new_type);
+
+  if (new_item)
+    GIMP_ITEM_GET_CLASS (new_item)->convert (new_item, dest_image, old_type);
+
+  return new_item;
+}
+
+/**
+ * gimp_item_rename:
+ * @item:     The #GimpItem to rename.
+ * @new_name: The new name to give the item.
+ * @error:    Return location for error message.
+ *
+ * This function assigns a new name to the item, if the desired name is
+ * different from the name it already has, and pushes an entry onto the
+ * undo stack for the item's image.  If @new_name is NULL or empty, the
+ * default name for the item's class is used.  If the name is changed,
+ * the GimpObject::name-changed signal is emitted for the item.
+ *
+ * Returns: %TRUE if the @item could be renamed, %FALSE otherwise.
+ */
+gboolean
+gimp_item_rename (GimpItem     *item,
+                  const gchar  *new_name,
+                  GError      **error)
+{
+  GimpItemClass *item_class;
+
+  g_return_val_if_fail (GIMP_IS_ITEM (item), FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  item_class = GIMP_ITEM_GET_CLASS (item);
+
+  if (! new_name || ! *new_name)
+    new_name = item_class->default_name;
+
+  if (strcmp (new_name, gimp_object_get_name (item)))
+    return item_class->rename (item, new_name, item_class->rename_desc, error);
+
+  return TRUE;
+}
+
+/**
+ * gimp_item_get_width:
+ * @item: The #GimpItem to check.
+ *
+ * Returns: The width of the item.
+ */
+gint
+gimp_item_get_width (GimpItem *item)
+{
+  g_return_val_if_fail (GIMP_IS_ITEM (item), -1);
+
+  return GET_PRIVATE (item)->width;
+}
+
+/**
+ * gimp_item_get_height:
+ * @item: The #GimpItem to check.
+ *
+ * Returns: The height of the item.
+ */
+gint
+gimp_item_get_height (GimpItem *item)
+{
+  g_return_val_if_fail (GIMP_IS_ITEM (item), -1);
+
+  return GET_PRIVATE (item)->height;
+}
+
+void
+gimp_item_set_size (GimpItem *item,
+                    gint      width,
+                    gint      height)
+{
+  GimpItemPrivate *private;
+
+  g_return_if_fail (GIMP_IS_ITEM (item));
+
+  private = GET_PRIVATE (item);
+
+  if (private->width  != width ||
+      private->height != height)
+    {
+      g_object_freeze_notify (G_OBJECT (item));
+
+      if (private->width != width)
+        {
+          private->width = width;
+          g_object_notify (G_OBJECT (item), "width");
+        }
+
+      if (private->height != height)
+        {
+          private->height = height;
+          g_object_notify (G_OBJECT (item), "height");
+        }
+
+      g_object_thaw_notify (G_OBJECT (item));
+
+      gimp_viewable_size_changed (GIMP_VIEWABLE (item));
+    }
+}
+
+/**
+ * gimp_item_get_offset:
+ * @item:     The #GimpItem to check.
+ * @offset_x: Return location for the item's X offset.
+ * @offset_y: Return location for the item's Y offset.
+ *
+ * Reveals the X and Y offsets of the item.
+ */
+void
+gimp_item_get_offset (GimpItem *item,
+                      gint     *offset_x,
+                      gint     *offset_y)
+{
+  GimpItemPrivate *private;
+
+  g_return_if_fail (GIMP_IS_ITEM (item));
+
+  private = GET_PRIVATE (item);
+
+  if (offset_x) *offset_x = private->offset_x;
+  if (offset_y) *offset_y = private->offset_y;
+}
+
+void
+gimp_item_set_offset (GimpItem *item,
+                      gint      offset_x,
+                      gint      offset_y)
+{
+  GimpItemPrivate *private;
+  GList           *list;
+
+  g_return_if_fail (GIMP_IS_ITEM (item));
+
+  private = GET_PRIVATE (item);
+
+  g_object_freeze_notify (G_OBJECT (item));
+
+  if (private->offset_x != offset_x)
+    {
+      private->offset_x = offset_x;
+      g_object_notify (G_OBJECT (item), "offset-x");
+    }
+
+  if (private->offset_y != offset_y)
+    {
+      private->offset_y = offset_y;
+      g_object_notify (G_OBJECT (item), "offset-y");
+    }
+
+  for (list = private->offset_nodes; list; list = g_list_next (list))
+    {
+      GeglNode *node = list->data;
+
+      gegl_node_set (node,
+                     "x", (gdouble) private->offset_x,
+                     "y", (gdouble) private->offset_y,
+                     NULL);
+    }
+
+  g_object_thaw_notify (G_OBJECT (item));
+}
+
+gint
+gimp_item_get_offset_x (GimpItem *item)
+{
+  g_return_val_if_fail (GIMP_IS_ITEM (item), 0);
+
+  return GET_PRIVATE (item)->offset_x;
+}
+
+gint
+gimp_item_get_offset_y (GimpItem *item)
+{
+  g_return_val_if_fail (GIMP_IS_ITEM (item), 0);
+
+  return GET_PRIVATE (item)->offset_y;
+}
+
+void
+gimp_item_start_move (GimpItem *item,
+                      gboolean  push_undo)
+{
+  g_return_if_fail (GIMP_IS_ITEM (item));
+
+  if (GIMP_ITEM_GET_CLASS (item)->start_move)
+    GIMP_ITEM_GET_CLASS (item)->start_move (item, push_undo);
+}
+
+void
+gimp_item_end_move (GimpItem *item,
+                    gboolean  push_undo)
+{
+  g_return_if_fail (GIMP_IS_ITEM (item));
+
+  if (GIMP_ITEM_GET_CLASS (item)->end_move)
+    GIMP_ITEM_GET_CLASS (item)->end_move (item, push_undo);
+}
+
+void
+gimp_item_start_transform (GimpItem *item,
+                           gboolean  push_undo)
+{
+  g_return_if_fail (GIMP_IS_ITEM (item));
+
+  if (GIMP_ITEM_GET_CLASS (item)->start_transform)
+    GIMP_ITEM_GET_CLASS (item)->start_transform (item, push_undo);
+}
+
+void
+gimp_item_end_transform (GimpItem *item,
+                         gboolean  push_undo)
+{
+  g_return_if_fail (GIMP_IS_ITEM (item));
+
+  if (GIMP_ITEM_GET_CLASS (item)->end_transform)
+    GIMP_ITEM_GET_CLASS (item)->end_transform (item, push_undo);
+}
+
+/**
+ * gimp_item_translate:
+ * @item:      The #GimpItem to move.
+ * @offset_x:  Increment to the X offset of the item.
+ * @offset_y:  Increment to the Y offset of the item.
+ * @push_undo: If #TRUE, create an entry in the image's undo stack
+ *             for this action.
+ *
+ * Adds the specified increments to the X and Y offsets for the item.
+ */
+void
+gimp_item_translate (GimpItem *item,
+                     gdouble   offset_x,
+                     gdouble   offset_y,
+                     gboolean  push_undo)
+{
+  GimpItemClass *item_class;
+  GimpImage     *image;
+
+  g_return_if_fail (GIMP_IS_ITEM (item));
+
+  item_class = GIMP_ITEM_GET_CLASS (item);
+  image = gimp_item_get_image (item);
+
+  if (! gimp_item_is_attached (item))
+    push_undo = FALSE;
+
+  if (push_undo)
+    gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_ITEM_DISPLACE,
+                                 item_class->translate_desc);
+
+  gimp_item_start_transform (item, push_undo);
+
+  item_class->translate (item, offset_x, offset_y, push_undo);
+
+  gimp_item_end_transform (item, push_undo);
+
+  if (push_undo)
+    gimp_image_undo_group_end (image);
+}
+
+/**
+ * gimp_item_check_scaling:
+ * @item:       Item to check
+ * @new_width:  proposed width of item, in pixels
+ * @new_height: proposed height of item, in pixels
+ *
+ * Scales item dimensions, then snaps them to pixel centers
+ *
+ * Returns: #FALSE if any dimension reduces to zero as a result
+ *          of this; otherwise, returns #TRUE.
+ **/
+gboolean
+gimp_item_check_scaling (GimpItem *item,
+                         gint      new_width,
+                         gint      new_height)
+{
+  GimpItemPrivate *private;
+  GimpImage       *image;
+  gdouble          img_scale_w;
+  gdouble          img_scale_h;
+  gint             new_item_offset_x;
+  gint             new_item_offset_y;
+  gint             new_item_width;
+  gint             new_item_height;
+
+  g_return_val_if_fail (GIMP_IS_ITEM (item), FALSE);
+
+  private = GET_PRIVATE (item);
+  image   = gimp_item_get_image (item);
+
+  img_scale_w       = ((gdouble) new_width /
+                       (gdouble) gimp_image_get_width (image));
+  img_scale_h       = ((gdouble) new_height /
+                       (gdouble) gimp_image_get_height (image));
+  new_item_offset_x = SIGNED_ROUND (img_scale_w * private->offset_x);
+  new_item_offset_y = SIGNED_ROUND (img_scale_h * private->offset_y);
+  new_item_width    = SIGNED_ROUND (img_scale_w * (private->offset_x +
+                                                   gimp_item_get_width (item))) -
+                      new_item_offset_x;
+  new_item_height   = SIGNED_ROUND (img_scale_h * (private->offset_y +
+                                                   gimp_item_get_height (item))) -
+                      new_item_offset_y;
+
+  return (new_item_width > 0 && new_item_height > 0);
+}
+
+void
+gimp_item_scale (GimpItem              *item,
+                 gint                   new_width,
+                 gint                   new_height,
+                 gint                   new_offset_x,
+                 gint                   new_offset_y,
+                 GimpInterpolationType  interpolation,
+                 GimpProgress          *progress)
+{
+  GimpItemClass *item_class;
+  GimpImage     *image;
+  gboolean       push_undo;
+
+  g_return_if_fail (GIMP_IS_ITEM (item));
+  g_return_if_fail (progress == NULL || GIMP_IS_PROGRESS (progress));
+
+  if (new_width < 1 || new_height < 1)
+    return;
+
+  item_class = GIMP_ITEM_GET_CLASS (item);
+  image = gimp_item_get_image (item);
+
+  push_undo = gimp_item_is_attached (item);
+
+  if (push_undo)
+    gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_ITEM_SCALE,
+                                 item_class->scale_desc);
+
+  gimp_item_start_transform (item, push_undo);
+
+  g_object_freeze_notify (G_OBJECT (item));
+
+  item_class->scale (item, new_width, new_height, new_offset_x, new_offset_y,
+                     interpolation, progress);
+
+  g_object_thaw_notify (G_OBJECT (item));
+
+  gimp_item_end_transform (item, push_undo);
+
+  if (push_undo)
+    gimp_image_undo_group_end (image);
+}
+
+/**
+ * gimp_item_scale_by_factors:
+ * @item:     Item to be transformed by explicit width and height factors.
+ * @w_factor: scale factor to apply to width and horizontal offset
+ * @h_factor: scale factor to apply to height and vertical offset
+ * @interpolation:
+ * @progress:
+ *
+ * Scales item dimensions and offsets by uniform width and
+ * height factors.
+ *
+ * Use gimp_item_scale_by_factors() in circumstances when the same
+ * width and height scaling factors are to be uniformly applied to a
+ * set of items. In this context, the item's dimensions and offsets
+ * from the sides of the containing image all change by these
+ * predetermined factors. By fiat, the fixed point of the transform is
+ * the upper left hand corner of the image. Returns #FALSE if a
+ * requested scale factor is zero or if a scaling zero's out a item
+ * dimension; returns #TRUE otherwise.
+ *
+ * Use gimp_item_scale() in circumstances where new item width
+ * and height dimensions are predetermined instead.
+ *
+ * Side effects: Undo set created for item. Old item imagery
+ *               scaled & painted to new item tiles.
+ *
+ * Returns: #TRUE, if the scaled item has positive dimensions
+ *          #FALSE if the scaled item has at least one zero dimension
+ **/
+gboolean
+gimp_item_scale_by_factors (GimpItem              *item,
+                            gdouble                w_factor,
+                            gdouble                h_factor,
+                            GimpInterpolationType  interpolation,
+                            GimpProgress          *progress)
+{
+  return gimp_item_scale_by_factors_with_origin (item,
+                                                 w_factor, h_factor,
+                                                 0, 0, 0, 0,
+                                                 interpolation, progress);
+}
+
+/**
+ * gimp_item_scale_by_factors:
+ * @item:         Item to be transformed by explicit width and height factors.
+ * @w_factor:     scale factor to apply to width and horizontal offset
+ * @h_factor:     scale factor to apply to height and vertical offset
+ * @origin_x:     x-coordinate of the transformation input origin
+ * @origin_y:     y-coordinate of the transformation input origin
+ * @new_origin_x: x-coordinate of the transformation output origin
+ * @new_origin_y: y-coordinate of the transformation output origin
+ * @interpolation:
+ * @progress:
+ *
+ * Same as gimp_item_scale_by_factors(), but with the option to specify
+ * custom input and output points of origin for the transformation.
+ *
+ * Returns: #TRUE, if the scaled item has positive dimensions
+ *          #FALSE if the scaled item has at least one zero dimension
+ **/
+gboolean
+gimp_item_scale_by_factors_with_origin (GimpItem              *item,
+                                        gdouble                w_factor,
+                                        gdouble                h_factor,
+                                        gint                   origin_x,
+                                        gint                   origin_y,
+                                        gint                   new_origin_x,
+                                        gint                   new_origin_y,
+                                        GimpInterpolationType  interpolation,
+                                        GimpProgress          *progress)
+{
+  GimpItemPrivate *private;
+  GimpContainer   *children;
+  gint             new_width, new_height;
+  gint             new_offset_x, new_offset_y;
+
+  g_return_val_if_fail (GIMP_IS_ITEM (item), FALSE);
+  g_return_val_if_fail (progress == NULL || GIMP_IS_PROGRESS (progress), FALSE);
+
+  private = GET_PRIVATE (item);
+
+  if (w_factor <= 0.0 || h_factor <= 0.0)
+    {
+      g_warning ("%s: requested width or height scale is non-positive",
+                 G_STRFUNC);
+      return FALSE;
+    }
+
+  children = gimp_viewable_get_children (GIMP_VIEWABLE (item));
+
+  /* avoid discarding empty layer groups */
+  if (children && gimp_container_is_empty (children))
+    return TRUE;
+
+  new_offset_x = SIGNED_ROUND (w_factor * (private->offset_x - origin_x));
+  new_offset_y = SIGNED_ROUND (h_factor * (private->offset_y - origin_y));
+  new_width    = SIGNED_ROUND (w_factor * (private->offset_x - origin_x +
+                                           gimp_item_get_width (item))) -
+                 new_offset_x;
+  new_height   = SIGNED_ROUND (h_factor * (private->offset_y - origin_y +
+                                           gimp_item_get_height (item))) -
+                 new_offset_y;
+
+  new_offset_x += new_origin_x;
+  new_offset_y += new_origin_y;
+
+  if (new_width > 0 && new_height > 0)
+    {
+      gimp_item_scale (item,
+                       new_width, new_height,
+                       new_offset_x, new_offset_y,
+                       interpolation, progress);
+      return TRUE;
+    }
+
+  return FALSE;
+}
+
+/**
+ * gimp_item_scale_by_origin:
+ * @item:         The item to be transformed by width & height scale factors
+ * @new_width:    The width that item will acquire
+ * @new_height:   The height that the item will acquire
+ * @interpolation:
+ * @progress:
+ * @local_origin: sets fixed point of the scaling transform. See below.
+ *
+ * Sets item dimensions to new_width and
+ * new_height. Derives vertical and horizontal scaling
+ * transforms from new width and height. If local_origin is
+ * #TRUE, the fixed point of the scaling transform coincides
+ * with the item's center point.  Otherwise, the fixed
+ * point is taken to be [-GimpItem::offset_x, -GimpItem::->offset_y].
+ *
+ * Since this function derives scale factors from new and
+ * current item dimensions, these factors will vary from
+ * item to item because of aliasing artifacts; factor
+ * variations among items can be quite large where item
+ * dimensions approach pixel dimensions. Use
+ * gimp_item_scale_by_factors() where constant scales are to
+ * be uniformly applied to a number of items.
+ *
+ * Side effects: undo set created for item.
+ *               Old item imagery scaled
+ *               & painted to new item tiles
+ **/
+void
+gimp_item_scale_by_origin (GimpItem              *item,
+                           gint                   new_width,
+                           gint                   new_height,
+                           GimpInterpolationType  interpolation,
+                           GimpProgress          *progress,
+                           gboolean               local_origin)
+{
+  GimpItemPrivate *private;
+  gint             new_offset_x, new_offset_y;
+
+  g_return_if_fail (GIMP_IS_ITEM (item));
+  g_return_if_fail (progress == NULL || GIMP_IS_PROGRESS (progress));
+
+  private = GET_PRIVATE (item);
+
+  if (new_width == 0 || new_height == 0)
+    {
+      g_warning ("%s: requested width or height equals zero", G_STRFUNC);
+      return;
+    }
+
+  if (local_origin)
+    {
+      new_offset_x = (private->offset_x +
+                      ((gimp_item_get_width  (item) - new_width)  / 2.0));
+      new_offset_y = (private->offset_y +
+                      ((gimp_item_get_height (item) - new_height) / 2.0));
+    }
+  else
+    {
+      new_offset_x = (gint) (((gdouble) new_width *
+                              (gdouble) private->offset_x /
+                              (gdouble) gimp_item_get_width (item)));
+
+      new_offset_y = (gint) (((gdouble) new_height *
+                              (gdouble) private->offset_y /
+                              (gdouble) gimp_item_get_height (item)));
+    }
+
+  gimp_item_scale (item,
+                   new_width, new_height,
+                   new_offset_x, new_offset_y,
+                   interpolation, progress);
+}
+
+void
+gimp_item_resize (GimpItem     *item,
+                  GimpContext  *context,
+                  GimpFillType  fill_type,
+                  gint          new_width,
+                  gint          new_height,
+                  gint          offset_x,
+                  gint          offset_y)
+{
+  GimpItemClass *item_class;
+  GimpImage     *image;
+  gboolean       push_undo;
+
+  g_return_if_fail (GIMP_IS_ITEM (item));
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  if (new_width < 1 || new_height < 1)
+    return;
+
+  item_class = GIMP_ITEM_GET_CLASS (item);
+  image = gimp_item_get_image (item);
+
+  push_undo = gimp_item_is_attached (item);
+
+  if (push_undo)
+    gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_ITEM_RESIZE,
+                                 item_class->resize_desc);
+
+  /* note that we call gimp_item_start_move(), and not
+   * gimp_item_start_transform().  whether or not a resize operation should be
+   * considered a transform operation, or a move operation, depends on the
+   * intended use of these functions by subclasses.  atm, we only use
+   * gimp_item_{start,end}_transform() to suspend mask resizing in group
+   * layers, which should not happen when reisizing a group, hence the call to
+   * gimp_item_start_move().
+   *
+   * see the comment in gimp_group_layer_resize() for more information.
+   */
+  gimp_item_start_move (item, push_undo);
+
+  g_object_freeze_notify (G_OBJECT (item));
+
+  item_class->resize (item, context, fill_type,
+                      new_width, new_height, offset_x, offset_y);
+
+  g_object_thaw_notify (G_OBJECT (item));
+
+  gimp_item_end_move (item, push_undo);
+
+  if (push_undo)
+    gimp_image_undo_group_end (image);
+}
+
+void
+gimp_item_flip (GimpItem            *item,
+                GimpContext         *context,
+                GimpOrientationType  flip_type,
+                gdouble              axis,
+                gboolean             clip_result)
+{
+  GimpItemClass *item_class;
+  GimpImage     *image;
+  gboolean       push_undo;
+
+  g_return_if_fail (GIMP_IS_ITEM (item));
+  g_return_if_fail (gimp_item_is_attached (item));
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  item_class = GIMP_ITEM_GET_CLASS (item);
+  image = gimp_item_get_image (item);
+
+  push_undo = gimp_item_is_attached (item);
+
+  if (push_undo)
+    gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_TRANSFORM,
+                                 item_class->flip_desc);
+
+  gimp_item_start_transform (item, push_undo);
+
+  g_object_freeze_notify (G_OBJECT (item));
+
+  item_class->flip (item, context, flip_type, axis, clip_result);
+
+  g_object_thaw_notify (G_OBJECT (item));
+
+  gimp_item_end_transform (item, push_undo);
+
+  if (push_undo)
+    gimp_image_undo_group_end (image);
+}
+
+void
+gimp_item_rotate (GimpItem         *item,
+                  GimpContext      *context,
+                  GimpRotationType  rotate_type,
+                  gdouble           center_x,
+                  gdouble           center_y,
+                  gboolean          clip_result)
+{
+  GimpItemClass *item_class;
+  GimpImage     *image;
+  gboolean       push_undo;
+
+  g_return_if_fail (GIMP_IS_ITEM (item));
+  g_return_if_fail (gimp_item_is_attached (item));
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  item_class = GIMP_ITEM_GET_CLASS (item);
+  image = gimp_item_get_image (item);
+
+  push_undo = gimp_item_is_attached (item);
+
+  if (push_undo)
+    gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_TRANSFORM,
+                                 item_class->rotate_desc);
+
+  gimp_item_start_transform (item, push_undo);
+
+  g_object_freeze_notify (G_OBJECT (item));
+
+  item_class->rotate (item, context, rotate_type, center_x, center_y,
+                      clip_result);
+
+  g_object_thaw_notify (G_OBJECT (item));
+
+  gimp_item_end_transform (item, push_undo);
+
+  if (push_undo)
+    gimp_image_undo_group_end (image);
+}
+
+void
+gimp_item_transform (GimpItem               *item,
+                     GimpContext            *context,
+                     const GimpMatrix3      *matrix,
+                     GimpTransformDirection  direction,
+                     GimpInterpolationType   interpolation,
+                     GimpTransformResize     clip_result,
+                     GimpProgress           *progress)
+{
+  GimpItemClass *item_class;
+  GimpImage     *image;
+  gboolean       push_undo;
+
+  g_return_if_fail (GIMP_IS_ITEM (item));
+  g_return_if_fail (gimp_item_is_attached (item));
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+  g_return_if_fail (matrix != NULL);
+  g_return_if_fail (progress == NULL || GIMP_IS_PROGRESS (progress));
+
+  item_class = GIMP_ITEM_GET_CLASS (item);
+  image = gimp_item_get_image (item);
+
+  push_undo = gimp_item_is_attached (item);
+
+  if (push_undo)
+    gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_TRANSFORM,
+                                 item_class->transform_desc);
+
+  gimp_item_start_transform (item, push_undo);
+
+  g_object_freeze_notify (G_OBJECT (item));
+
+  item_class->transform (item, context, matrix, direction, interpolation,
+                         clip_result, progress);
+
+  g_object_thaw_notify (G_OBJECT (item));
+
+  gimp_item_end_transform (item, push_undo);
+
+  if (push_undo)
+    gimp_image_undo_group_end (image);
+}
+
+GimpTransformResize
+gimp_item_get_clip (GimpItem            *item,
+                    GimpTransformResize  clip_result)
+{
+  g_return_val_if_fail (GIMP_IS_ITEM (item), GIMP_TRANSFORM_RESIZE_ADJUST);
+
+  return GIMP_ITEM_GET_CLASS (item)->get_clip (item, clip_result);
+}
+
+gboolean
+gimp_item_fill (GimpItem        *item,
+                GimpDrawable    *drawable,
+                GimpFillOptions *fill_options,
+                gboolean         push_undo,
+                GimpProgress    *progress,
+                GError         **error)
+{
+  GimpItemClass *item_class;
+  gboolean       retval = FALSE;
+
+  g_return_val_if_fail (GIMP_IS_ITEM (item), FALSE);
+  g_return_val_if_fail (gimp_item_is_attached (item), FALSE);
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), FALSE);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (drawable)), FALSE);
+  g_return_val_if_fail (GIMP_IS_FILL_OPTIONS (fill_options), FALSE);
+  g_return_val_if_fail (progress == NULL || GIMP_IS_PROGRESS (progress), FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  item_class = GIMP_ITEM_GET_CLASS (item);
+
+  if (item_class->fill)
+    {
+      GimpImage *image = gimp_item_get_image (item);
+
+      if (push_undo)
+        gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_PAINT,
+                                     item_class->fill_desc);
+
+      retval = item_class->fill (item, drawable, fill_options, push_undo,
+                                 progress, error);
+
+      if (push_undo)
+        gimp_image_undo_group_end (image);
+    }
+
+  return retval;
+}
+
+gboolean
+gimp_item_stroke (GimpItem          *item,
+                  GimpDrawable      *drawable,
+                  GimpContext       *context,
+                  GimpStrokeOptions *stroke_options,
+                  GimpPaintOptions  *paint_options,
+                  gboolean           push_undo,
+                  GimpProgress      *progress,
+                  GError           **error)
+{
+  GimpItemClass *item_class;
+  gboolean       retval = FALSE;
+
+  g_return_val_if_fail (GIMP_IS_ITEM (item), FALSE);
+  g_return_val_if_fail (gimp_item_is_attached (item), FALSE);
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), FALSE);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (drawable)), FALSE);
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), FALSE);
+  g_return_val_if_fail (GIMP_IS_STROKE_OPTIONS (stroke_options), FALSE);
+  g_return_val_if_fail (paint_options == NULL ||
+                        GIMP_IS_PAINT_OPTIONS (paint_options), FALSE);
+  g_return_val_if_fail (progress == NULL || GIMP_IS_PROGRESS (progress), FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  item_class = GIMP_ITEM_GET_CLASS (item);
+
+  if (item_class->stroke)
+    {
+      GimpImage *image = gimp_item_get_image (item);
+
+      gimp_stroke_options_prepare (stroke_options, context, paint_options);
+
+      if (push_undo)
+        gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_PAINT,
+                                     item_class->stroke_desc);
+
+      retval = item_class->stroke (item, drawable, stroke_options, push_undo,
+                                   progress, error);
+
+      if (push_undo)
+        gimp_image_undo_group_end (image);
+
+      gimp_stroke_options_finish (stroke_options);
+    }
+
+  return retval;
+}
+
+void
+gimp_item_to_selection (GimpItem       *item,
+                        GimpChannelOps  op,
+                        gboolean        antialias,
+                        gboolean        feather,
+                        gdouble         feather_radius_x,
+                        gdouble         feather_radius_y)
+{
+  GimpItemClass *item_class;
+
+  g_return_if_fail (GIMP_IS_ITEM (item));
+  g_return_if_fail (gimp_item_is_attached (item));
+
+  item_class = GIMP_ITEM_GET_CLASS (item);
+
+  if (item_class->to_selection)
+    item_class->to_selection (item, op, antialias,
+                              feather, feather_radius_x, feather_radius_y);
+}
+
+void
+gimp_item_add_offset_node (GimpItem *item,
+                           GeglNode *node)
+{
+  GimpItemPrivate *private;
+
+  g_return_if_fail (GIMP_IS_ITEM (item));
+  g_return_if_fail (GEGL_IS_NODE (node));
+
+  private = GET_PRIVATE (item);
+
+  g_return_if_fail (g_list_find (private->offset_nodes, node) == NULL);
+
+  gegl_node_set (node,
+                 "x", (gdouble) private->offset_x,
+                 "y", (gdouble) private->offset_y,
+                 NULL);
+
+  private->offset_nodes = g_list_append (private->offset_nodes,
+                                         g_object_ref (node));
+}
+
+void
+gimp_item_remove_offset_node (GimpItem *item,
+                              GeglNode *node)
+{
+  GimpItemPrivate *private;
+
+  g_return_if_fail (GIMP_IS_ITEM (item));
+  g_return_if_fail (GEGL_IS_NODE (node));
+
+  private = GET_PRIVATE (item);
+
+  g_return_if_fail (g_list_find (private->offset_nodes, node) != NULL);
+
+  private->offset_nodes = g_list_remove (private->offset_nodes, node);
+  g_object_unref (node);
+}
+
+gint
+gimp_item_get_ID (GimpItem *item)
+{
+  g_return_val_if_fail (GIMP_IS_ITEM (item), -1);
+
+  return GET_PRIVATE (item)->ID;
+}
+
+GimpItem *
+gimp_item_get_by_ID (Gimp *gimp,
+                     gint  item_id)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  if (gimp->item_table == NULL)
+    return NULL;
+
+  return (GimpItem *) gimp_id_table_lookup (gimp->item_table, item_id);
+}
+
+GimpTattoo
+gimp_item_get_tattoo (GimpItem *item)
+{
+  g_return_val_if_fail (GIMP_IS_ITEM (item), 0);
+
+  return GET_PRIVATE (item)->tattoo;
+}
+
+void
+gimp_item_set_tattoo (GimpItem   *item,
+                      GimpTattoo  tattoo)
+{
+  g_return_if_fail (GIMP_IS_ITEM (item));
+
+  GET_PRIVATE (item)->tattoo = tattoo;
+}
+
+GimpImage *
+gimp_item_get_image (GimpItem *item)
+{
+  g_return_val_if_fail (GIMP_IS_ITEM (item), NULL);
+
+  return GET_PRIVATE (item)->image;
+}
+
+void
+gimp_item_set_image (GimpItem  *item,
+                     GimpImage *image)
+{
+  GimpItemPrivate *private;
+
+  g_return_if_fail (GIMP_IS_ITEM (item));
+  g_return_if_fail (! gimp_item_is_attached (item));
+  g_return_if_fail (! gimp_item_is_removed (item));
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  private = GET_PRIVATE (item);
+
+  if (image == private->image)
+    return;
+
+  g_object_freeze_notify (G_OBJECT (item));
+
+  if (private->ID == 0)
+    {
+      private->ID = gimp_id_table_insert (image->gimp->item_table, item);
+
+      g_object_notify (G_OBJECT (item), "id");
+    }
+
+  if (private->tattoo == 0 || private->image != image)
+    {
+      private->tattoo = gimp_image_get_new_tattoo (image);
+    }
+
+  private->image = image;
+  g_object_notify (G_OBJECT (item), "image");
+
+  g_object_thaw_notify (G_OBJECT (item));
+}
+
+/**
+ * gimp_item_replace_item:
+ * @item: a newly allocated #GimpItem
+ * @replace: the #GimpItem to be replaced by @item
+ *
+ * This function shouly only be called right after @item has been
+ * newly allocated.
+ *
+ * Replaces @replace by @item, as far as possible within the #GimpItem
+ * class. The new @item takes over @replace's ID, tattoo, offset, size
+ * etc. and all these properties are set to %NULL on @replace.
+ *
+ * This function *only* exists to allow subclasses to do evil hacks
+ * like in XCF text layer loading. Don't ever use this function if you
+ * are not sure.
+ *
+ * After this function returns, @replace has become completely
+ * unusable, should only be used to steal everything it has (like its
+ * drawable properties if it's a drawable), and then be destroyed.
+ **/
+void
+gimp_item_replace_item (GimpItem *item,
+                        GimpItem *replace)
+{
+  GimpItemPrivate *private;
+  gint             offset_x;
+  gint             offset_y;
+
+  g_return_if_fail (GIMP_IS_ITEM (item));
+  g_return_if_fail (! gimp_item_is_attached (item));
+  g_return_if_fail (! gimp_item_is_removed (item));
+  g_return_if_fail (GIMP_IS_ITEM (replace));
+
+  private = GET_PRIVATE (item);
+
+  gimp_object_set_name (GIMP_OBJECT (item), gimp_object_get_name (replace));
+
+  if (private->ID)
+    gimp_id_table_remove (gimp_item_get_image (item)->gimp->item_table,
+                          gimp_item_get_ID (item));
+
+  private->ID = gimp_item_get_ID (replace);
+  gimp_id_table_replace (gimp_item_get_image (item)->gimp->item_table,
+                         gimp_item_get_ID (item),
+                         item);
+
+  /* Set image before tattoo so that the explicitly set tattoo overrides
+   * the one implicitly set when setting the image
+   */
+  gimp_item_set_image (item, gimp_item_get_image (replace));
+  GET_PRIVATE (replace)->image  = NULL;
+
+  gimp_item_set_tattoo (item, gimp_item_get_tattoo (replace));
+  gimp_item_set_tattoo (replace, 0);
+
+  g_object_unref (private->parasites);
+  private->parasites = GET_PRIVATE (replace)->parasites;
+  GET_PRIVATE (replace)->parasites = NULL;
+
+  gimp_item_get_offset (replace, &offset_x, &offset_y);
+  gimp_item_set_offset (item, offset_x, offset_y);
+
+  gimp_item_set_size (item,
+                      gimp_item_get_width  (replace),
+                      gimp_item_get_height (replace));
+
+  gimp_item_set_visible       (item, gimp_item_get_visible (replace), FALSE);
+  gimp_item_set_linked        (item, gimp_item_get_linked (replace), FALSE);
+  gimp_item_set_color_tag     (item, gimp_item_get_color_tag (replace), FALSE);
+  gimp_item_set_lock_content  (item, gimp_item_get_lock_content (replace), FALSE);
+  gimp_item_set_lock_position (item, gimp_item_get_lock_position (replace), FALSE);
+}
+
+/**
+ * gimp_item_set_parasites:
+ * @item: a #GimpItem
+ * @parasites: a #GimpParasiteList
+ *
+ * Set an @item's #GimpParasiteList. It's usually never needed to
+ * fiddle with an item's parasite list directly. This function exists
+ * for special purposes only, like when creating items from unusual
+ * sources.
+ **/
+void
+gimp_item_set_parasites (GimpItem         *item,
+                         GimpParasiteList *parasites)
+{
+  GimpItemPrivate *private;
+
+  g_return_if_fail (GIMP_IS_ITEM (item));
+  g_return_if_fail (GIMP_IS_PARASITE_LIST (parasites));
+
+  private = GET_PRIVATE (item);
+
+  g_set_object (&private->parasites, parasites);
+}
+
+/**
+ * gimp_item_get_parasites:
+ * @item: a #GimpItem
+ *
+ * Get an @item's #GimpParasiteList. It's usually never needed to
+ * fiddle with an item's parasite list directly. This function exists
+ * for special purposes only, like when saving an item to XCF.
+ *
+ * Return value: The @item's #GimpParasiteList.
+ **/
+GimpParasiteList *
+gimp_item_get_parasites (GimpItem *item)
+{
+  g_return_val_if_fail (GIMP_IS_ITEM (item), NULL);
+
+  return GET_PRIVATE (item)->parasites;
+}
+
+gboolean
+gimp_item_parasite_validate (GimpItem            *item,
+                             const GimpParasite  *parasite,
+                             GError             **error)
+{
+  g_return_val_if_fail (GIMP_IS_ITEM (item), FALSE);
+  g_return_val_if_fail (parasite != NULL, FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  return TRUE;
+}
+
+void
+gimp_item_parasite_attach (GimpItem           *item,
+                           const GimpParasite *parasite,
+                           gboolean            push_undo)
+{
+  GimpItemPrivate *private;
+  GimpParasite     copy;
+
+  g_return_if_fail (GIMP_IS_ITEM (item));
+  g_return_if_fail (parasite != NULL);
+
+  private = GET_PRIVATE (item);
+
+  /*  make a temporary copy of the GimpParasite struct because
+   *  gimp_parasite_shift_parent() changes it
+   */
+  copy = *parasite;
+
+  if (! gimp_item_is_attached (item))
+    push_undo = FALSE;
+
+  if (push_undo)
+    {
+      /*  only set the dirty bit manually if we can be saved and the new
+       *  parasite differs from the current one and we aren't undoable
+       */
+      if (gimp_parasite_is_undoable (&copy))
+        {
+          /* do a group in case we have attach_parent set */
+          gimp_image_undo_group_start (private->image,
+                                       GIMP_UNDO_GROUP_PARASITE_ATTACH,
+                                       C_("undo-type", "Attach Parasite"));
+
+          gimp_image_undo_push_item_parasite (private->image, NULL, item, &copy);
+        }
+      else if (gimp_parasite_is_persistent (&copy) &&
+               ! gimp_parasite_compare (&copy,
+                                        gimp_item_parasite_find
+                                        (item, gimp_parasite_name (&copy))))
+        {
+          gimp_image_undo_push_cantundo (private->image,
+                                         C_("undo-type", "Attach Parasite to Item"));
+        }
+    }
+
+  gimp_parasite_list_add (private->parasites, &copy);
+
+  if (gimp_parasite_has_flag (&copy, GIMP_PARASITE_ATTACH_PARENT))
+    {
+      gimp_parasite_shift_parent (&copy);
+      gimp_image_parasite_attach (private->image, &copy, TRUE);
+    }
+  else if (gimp_parasite_has_flag (&copy, GIMP_PARASITE_ATTACH_GRANDPARENT))
+    {
+      gimp_parasite_shift_parent (&copy);
+      gimp_parasite_shift_parent (&copy);
+      gimp_parasite_attach (private->image->gimp, &copy);
+    }
+
+  if (gimp_item_is_attached (item) &&
+      gimp_parasite_is_undoable (&copy))
+    {
+      gimp_image_undo_group_end (private->image);
+    }
+}
+
+void
+gimp_item_parasite_detach (GimpItem    *item,
+                           const gchar *name,
+                           gboolean     push_undo)
+{
+  GimpItemPrivate    *private;
+  const GimpParasite *parasite;
+
+  g_return_if_fail (GIMP_IS_ITEM (item));
+  g_return_if_fail (name != NULL);
+
+  private = GET_PRIVATE (item);
+
+  parasite = gimp_parasite_list_find (private->parasites, name);
+
+  if (! parasite)
+    return;
+
+  if (! gimp_item_is_attached (item))
+    push_undo = FALSE;
+
+  if (push_undo)
+    {
+      if (gimp_parasite_is_undoable (parasite))
+        {
+          gimp_image_undo_push_item_parasite_remove (private->image,
+                                                     C_("undo-type", "Remove Parasite from Item"),
+                                                     item,
+                                                     gimp_parasite_name (parasite));
+        }
+      else if (gimp_parasite_is_persistent (parasite))
+        {
+          gimp_image_undo_push_cantundo (private->image,
+                                         C_("undo-type", "Remove Parasite from Item"));
+        }
+    }
+
+  gimp_parasite_list_remove (private->parasites, name);
+}
+
+const GimpParasite *
+gimp_item_parasite_find (GimpItem    *item,
+                         const gchar *name)
+{
+  g_return_val_if_fail (GIMP_IS_ITEM (item), NULL);
+
+  return gimp_parasite_list_find (GET_PRIVATE (item)->parasites, name);
+}
+
+static void
+gimp_item_parasite_list_foreach_func (gchar          *name,
+                                      GimpParasite   *parasite,
+                                      gchar        ***cur)
+{
+  *(*cur)++ = (gchar *) g_strdup (name);
+}
+
+gchar **
+gimp_item_parasite_list (GimpItem *item,
+                         gint     *count)
+{
+  GimpItemPrivate  *private;
+  gchar           **list;
+  gchar           **cur;
+
+  g_return_val_if_fail (GIMP_IS_ITEM (item), NULL);
+  g_return_val_if_fail (count != NULL, NULL);
+
+  private = GET_PRIVATE (item);
+
+  *count = gimp_parasite_list_length (private->parasites);
+
+  cur = list = g_new (gchar *, *count);
+
+  gimp_parasite_list_foreach (private->parasites,
+                              (GHFunc) gimp_item_parasite_list_foreach_func,
+                              &cur);
+
+  return list;
+}
+
+void
+gimp_item_set_visible (GimpItem *item,
+                       gboolean  visible,
+                       gboolean  push_undo)
+{
+  g_return_if_fail (GIMP_IS_ITEM (item));
+
+  visible = visible ? TRUE : FALSE;
+
+  if (gimp_item_get_visible (item) != visible)
+    {
+      if (push_undo && gimp_item_is_attached (item))
+        {
+          GimpImage *image = gimp_item_get_image (item);
+
+          if (image)
+            gimp_image_undo_push_item_visibility (image, NULL, item);
+        }
+
+      GET_PRIVATE (item)->visible = visible;
+
+      if (GET_PRIVATE (item)->bind_visible_to_active)
+        gimp_filter_set_active (GIMP_FILTER (item), visible);
+
+      g_signal_emit (item, gimp_item_signals[VISIBILITY_CHANGED], 0);
+
+      g_object_notify (G_OBJECT (item), "visible");
+    }
+}
+
+gboolean
+gimp_item_get_visible (GimpItem *item)
+{
+  g_return_val_if_fail (GIMP_IS_ITEM (item), FALSE);
+
+  return GET_PRIVATE (item)->visible;
+}
+
+gboolean
+gimp_item_is_visible (GimpItem *item)
+{
+  g_return_val_if_fail (GIMP_IS_ITEM (item), FALSE);
+
+  if (gimp_item_get_visible (item))
+    {
+      GimpItem *parent;
+
+      parent = GIMP_ITEM (gimp_viewable_get_parent (GIMP_VIEWABLE (item)));
+
+      if (parent)
+        return gimp_item_is_visible (parent);
+
+      return TRUE;
+    }
+
+  return FALSE;
+}
+
+void
+gimp_item_bind_visible_to_active (GimpItem *item,
+                                  gboolean  bind)
+{
+  g_return_if_fail (GIMP_IS_ITEM (item));
+
+  GET_PRIVATE (item)->bind_visible_to_active = bind;
+
+  if (bind)
+    gimp_filter_set_active (GIMP_FILTER (item), gimp_item_get_visible (item));
+}
+
+void
+gimp_item_set_linked (GimpItem *item,
+                      gboolean  linked,
+                      gboolean  push_undo)
+{
+  g_return_if_fail (GIMP_IS_ITEM (item));
+
+  linked = linked ? TRUE : FALSE;
+
+  if (gimp_item_get_linked (item) != linked)
+    {
+      GimpImage *image       = gimp_item_get_image (item);
+      gboolean   is_attached = gimp_item_is_attached (item);
+
+      if (push_undo && is_attached && image)
+        gimp_image_undo_push_item_linked (image, NULL, item);
+
+      GET_PRIVATE (item)->linked = linked;
+
+      g_signal_emit (item, gimp_item_signals[LINKED_CHANGED], 0);
+
+      if (is_attached && image)
+        gimp_image_linked_items_changed (image);
+
+      g_object_notify (G_OBJECT (item), "linked");
+    }
+}
+
+gboolean
+gimp_item_get_linked (GimpItem *item)
+{
+  g_return_val_if_fail (GIMP_IS_ITEM (item), FALSE);
+
+  return GET_PRIVATE (item)->linked;
+}
+
+void
+gimp_item_set_color_tag (GimpItem     *item,
+                         GimpColorTag  color_tag,
+                         gboolean      push_undo)
+{
+  g_return_if_fail (GIMP_IS_ITEM (item));
+
+  if (gimp_item_get_color_tag (item) != color_tag)
+    {
+      if (push_undo && gimp_item_is_attached (item))
+        {
+          GimpImage *image = gimp_item_get_image (item);
+
+          if (image)
+            gimp_image_undo_push_item_color_tag (image, NULL, item);
+        }
+
+      GET_PRIVATE (item)->color_tag = color_tag;
+
+      g_signal_emit (item, gimp_item_signals[COLOR_TAG_CHANGED], 0);
+
+      g_object_notify (G_OBJECT (item), "color-tag");
+    }
+}
+
+GimpColorTag
+gimp_item_get_color_tag (GimpItem *item)
+{
+  g_return_val_if_fail (GIMP_IS_ITEM (item), GIMP_COLOR_TAG_NONE);
+
+  return GET_PRIVATE (item)->color_tag;
+}
+
+GimpColorTag
+gimp_item_get_merged_color_tag (GimpItem *item)
+{
+  g_return_val_if_fail (GIMP_IS_ITEM (item), GIMP_COLOR_TAG_NONE);
+
+  if (gimp_item_get_color_tag (item) == GIMP_COLOR_TAG_NONE)
+    {
+      GimpItem *parent;
+
+      parent = GIMP_ITEM (gimp_viewable_get_parent (GIMP_VIEWABLE (item)));
+
+      if (parent)
+        return gimp_item_get_merged_color_tag (parent);
+    }
+
+  return gimp_item_get_color_tag (item);
+}
+
+void
+gimp_item_set_lock_content (GimpItem *item,
+                            gboolean  lock_content,
+                            gboolean  push_undo)
+{
+  g_return_if_fail (GIMP_IS_ITEM (item));
+  g_return_if_fail (gimp_item_can_lock_content (item));
+
+  lock_content = lock_content ? TRUE : FALSE;
+
+  if (gimp_item_get_lock_content (item) != lock_content)
+    {
+      if (push_undo && gimp_item_is_attached (item))
+        {
+          /* Right now I don't think this should be pushed. */
+#if 0
+          GimpImage *image = gimp_item_get_image (item);
+
+          gimp_image_undo_push_item_lock_content (image, NULL, item);
+#endif
+        }
+
+      GET_PRIVATE (item)->lock_content = lock_content;
+
+      g_signal_emit (item, gimp_item_signals[LOCK_CONTENT_CHANGED], 0);
+
+      g_object_notify (G_OBJECT (item), "lock-content");
+    }
+}
+
+gboolean
+gimp_item_get_lock_content (GimpItem *item)
+{
+  g_return_val_if_fail (GIMP_IS_ITEM (item), FALSE);
+
+  return GET_PRIVATE (item)->lock_content;
+}
+
+gboolean
+gimp_item_can_lock_content (GimpItem *item)
+{
+  g_return_val_if_fail (GIMP_IS_ITEM (item), FALSE);
+
+  return TRUE;
+}
+
+gboolean
+gimp_item_is_content_locked (GimpItem *item)
+{
+  g_return_val_if_fail (GIMP_IS_ITEM (item), FALSE);
+
+  return GIMP_ITEM_GET_CLASS (item)->is_content_locked (item);
+}
+
+void
+gimp_item_set_lock_position (GimpItem *item,
+                             gboolean  lock_position,
+                             gboolean  push_undo)
+{
+  g_return_if_fail (GIMP_IS_ITEM (item));
+  g_return_if_fail (gimp_item_can_lock_position (item));
+
+  lock_position = lock_position ? TRUE : FALSE;
+
+  if (gimp_item_get_lock_position (item) != lock_position)
+    {
+      if (push_undo && gimp_item_is_attached (item))
+        {
+          GimpImage *image = gimp_item_get_image (item);
+
+          gimp_image_undo_push_item_lock_position (image, NULL, item);
+        }
+
+      GET_PRIVATE (item)->lock_position = lock_position;
+
+      g_signal_emit (item, gimp_item_signals[LOCK_POSITION_CHANGED], 0);
+
+      g_object_notify (G_OBJECT (item), "lock-position");
+    }
+}
+
+gboolean
+gimp_item_get_lock_position (GimpItem *item)
+{
+  g_return_val_if_fail (GIMP_IS_ITEM (item), FALSE);
+
+  return GET_PRIVATE (item)->lock_position;
+}
+
+gboolean
+gimp_item_can_lock_position (GimpItem *item)
+{
+  g_return_val_if_fail (GIMP_IS_ITEM (item), FALSE);
+
+  if (gimp_viewable_get_children (GIMP_VIEWABLE (item)))
+    return FALSE;
+
+  return TRUE;
+}
+
+gboolean
+gimp_item_is_position_locked (GimpItem *item)
+{
+  g_return_val_if_fail (GIMP_IS_ITEM (item), FALSE);
+
+  return GIMP_ITEM_GET_CLASS (item)->is_position_locked (item);
+}
+
+gboolean
+gimp_item_mask_bounds (GimpItem *item,
+                       gint     *x1,
+                       gint     *y1,
+                       gint     *x2,
+                       gint     *y2)
+{
+  GimpImage   *image;
+  GimpChannel *selection;
+  gint         x, y, width, height;
+  gboolean     retval;
+
+  g_return_val_if_fail (GIMP_IS_ITEM (item), FALSE);
+  g_return_val_if_fail (gimp_item_is_attached (item), FALSE);
+
+  image     = gimp_item_get_image (item);
+  selection = gimp_image_get_mask (image);
+
+  /* check for is_empty() before intersecting so we ignore the
+   * selection if it is suspended (like when stroking)
+   */
+  if (GIMP_ITEM (selection) != item       &&
+      ! gimp_channel_is_empty (selection) &&
+      gimp_item_bounds (GIMP_ITEM (selection), &x, &y, &width, &height))
+    {
+      gint off_x, off_y;
+      gint x2, y2;
+
+      gimp_item_get_offset (item, &off_x, &off_y);
+
+      x2 = x + width;
+      y2 = y + height;
+
+      x  = CLAMP (x  - off_x, 0, gimp_item_get_width  (item));
+      y  = CLAMP (y  - off_y, 0, gimp_item_get_height (item));
+      x2 = CLAMP (x2 - off_x, 0, gimp_item_get_width  (item));
+      y2 = CLAMP (y2 - off_y, 0, gimp_item_get_height (item));
+
+      width  = x2 - x;
+      height = y2 - y;
+
+      retval = TRUE;
+    }
+  else
+    {
+      x      = 0;
+      y      = 0;
+      width  = gimp_item_get_width  (item);
+      height = gimp_item_get_height (item);
+
+      retval = FALSE;
+    }
+
+  if (x1) *x1 = x;
+  if (y1) *y1 = y;
+  if (x2) *x2 = x + width;
+  if (y2) *y2 = y + height;
+
+  return retval;
+}
+
+/**
+ * gimp_item_mask_intersect:
+ * @item:   a #GimpItem
+ * @x:      return location for x
+ * @y:      return location for y
+ * @width:  return location for the width
+ * @height: return location for the height
+ *
+ * Intersect the area of the @item and its image's selection mask.
+ * The computed area is the bounding box of he selection within the
+ * item.
+ **/
+gboolean
+gimp_item_mask_intersect (GimpItem *item,
+                          gint     *x,
+                          gint     *y,
+                          gint     *width,
+                          gint     *height)
+{
+  GimpImage   *image;
+  GimpChannel *selection;
+  gint         tmp_x, tmp_y;
+  gint         tmp_width, tmp_height;
+  gboolean     retval;
+
+  g_return_val_if_fail (GIMP_IS_ITEM (item), FALSE);
+  g_return_val_if_fail (gimp_item_is_attached (item), FALSE);
+
+  image     = gimp_item_get_image (item);
+  selection = gimp_image_get_mask (image);
+
+  /* check for is_empty() before intersecting so we ignore the
+   * selection if it is suspended (like when stroking)
+   */
+  if (GIMP_ITEM (selection) != item       &&
+      ! gimp_channel_is_empty (selection) &&
+      gimp_item_bounds (GIMP_ITEM (selection),
+                        &tmp_x, &tmp_y, &tmp_width, &tmp_height))
+    {
+      gint off_x, off_y;
+
+      gimp_item_get_offset (item, &off_x, &off_y);
+
+      retval = gimp_rectangle_intersect (tmp_x - off_x, tmp_y - off_y,
+                                         tmp_width, tmp_height,
+                                         0, 0,
+                                         gimp_item_get_width  (item),
+                                         gimp_item_get_height (item),
+                                         &tmp_x, &tmp_y,
+                                         &tmp_width, &tmp_height);
+    }
+  else
+    {
+      tmp_x      = 0;
+      tmp_y      = 0;
+      tmp_width  = gimp_item_get_width  (item);
+      tmp_height = gimp_item_get_height (item);
+
+      retval = TRUE;
+    }
+
+  if (x)      *x      = tmp_x;
+  if (y)      *y      = tmp_y;
+  if (width)  *width  = tmp_width;
+  if (height) *height = tmp_height;
+
+  return retval;
+}
+
+gboolean
+gimp_item_is_in_set (GimpItem    *item,
+                     GimpItemSet  set)
+{
+  GimpItemPrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_ITEM (item), FALSE);
+
+  private = GET_PRIVATE (item);
+
+  switch (set)
+    {
+    case GIMP_ITEM_SET_NONE:
+      return FALSE;
+
+    case GIMP_ITEM_SET_ALL:
+      return TRUE;
+
+    case GIMP_ITEM_SET_IMAGE_SIZED:
+      return (gimp_item_get_width  (item) == gimp_image_get_width  (private->image) &&
+              gimp_item_get_height (item) == gimp_image_get_height (private->image));
+
+    case GIMP_ITEM_SET_VISIBLE:
+      return gimp_item_get_visible (item);
+
+    case GIMP_ITEM_SET_LINKED:
+      return gimp_item_get_linked (item);
+    }
+
+  return FALSE;
+}
diff --git a/app/core/gimpitem.h b/app/core/gimpitem.h
new file mode 100644
index 0000000..6bc56e3
--- /dev/null
+++ b/app/core/gimpitem.h
@@ -0,0 +1,405 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_ITEM_H__
+#define __GIMP_ITEM_H__
+
+
+#include "gimpfilter.h"
+
+
+#define GIMP_TYPE_ITEM            (gimp_item_get_type ())
+#define GIMP_ITEM(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_ITEM, GimpItem))
+#define GIMP_ITEM_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_ITEM, GimpItemClass))
+#define GIMP_IS_ITEM(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_ITEM))
+#define GIMP_IS_ITEM_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_ITEM))
+#define GIMP_ITEM_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_ITEM, GimpItemClass))
+
+
+typedef struct _GimpItemClass GimpItemClass;
+
+struct _GimpItem
+{
+  GimpFilter  parent_instance;
+};
+
+struct _GimpItemClass
+{
+  GimpFilterClass  parent_class;
+
+  /*  signals  */
+  void            (* removed)               (GimpItem            *item);
+  void            (* visibility_changed)    (GimpItem            *item);
+  void            (* linked_changed)        (GimpItem            *item);
+  void            (* color_tag_changed)     (GimpItem            *item);
+  void            (* lock_content_changed)  (GimpItem            *item);
+  void            (* lock_position_changed) (GimpItem            *item);
+
+  /*  virtual functions  */
+  void            (* unset_removed)      (GimpItem               *item);
+  gboolean        (* is_attached)        (GimpItem               *item);
+  gboolean        (* is_content_locked)  (GimpItem               *item);
+  gboolean        (* is_position_locked) (GimpItem               *item);
+  GimpItemTree  * (* get_tree)           (GimpItem               *item);
+  gboolean        (* bounds)             (GimpItem               *item,
+                                          gdouble                *x,
+                                          gdouble                *y,
+                                          gdouble                *width,
+                                          gdouble                *height);
+  GimpItem      * (* duplicate)          (GimpItem               *item,
+                                          GType                   new_type);
+  void            (* convert)            (GimpItem               *item,
+                                          GimpImage              *dest_image,
+                                          GType                   old_type);
+  gboolean        (* rename)             (GimpItem               *item,
+                                          const gchar            *new_name,
+                                          const gchar            *undo_desc,
+                                          GError                **error);
+  void            (* start_move)         (GimpItem               *item,
+                                          gboolean                push_undo);
+  void            (* end_move)           (GimpItem               *item,
+                                          gboolean                push_undo);
+  void            (* start_transform)    (GimpItem               *item,
+                                          gboolean                push_undo);
+  void            (* end_transform)      (GimpItem               *item,
+                                          gboolean                push_undo);
+  void            (* translate)          (GimpItem               *item,
+                                          gdouble                 offset_x,
+                                          gdouble                 offset_y,
+                                          gboolean                push_undo);
+  void            (* scale)              (GimpItem               *item,
+                                          gint                    new_width,
+                                          gint                    new_height,
+                                          gint                    new_offset_x,
+                                          gint                    new_offset_y,
+                                          GimpInterpolationType   interpolation_type,
+                                          GimpProgress           *progress);
+  void            (* resize)             (GimpItem               *item,
+                                          GimpContext            *context,
+                                          GimpFillType            fill_type,
+                                          gint                    new_width,
+                                          gint                    new_height,
+                                          gint                    offset_x,
+                                          gint                    offset_y);
+  void            (* flip)               (GimpItem               *item,
+                                          GimpContext            *context,
+                                          GimpOrientationType     flip_type,
+                                          gdouble                 axis,
+                                          gboolean                clip_result);
+  void            (* rotate)             (GimpItem               *item,
+                                          GimpContext            *context,
+                                          GimpRotationType        rotate_type,
+                                          gdouble                 center_x,
+                                          gdouble                 center_y,
+                                          gboolean                clip_result);
+  void            (* transform)          (GimpItem               *item,
+                                          GimpContext            *context,
+                                          const GimpMatrix3      *matrix,
+                                          GimpTransformDirection  direction,
+                                          GimpInterpolationType   interpolation_type,
+                                          GimpTransformResize     clip_result,
+                                          GimpProgress           *progress);
+  GimpTransformResize (* get_clip)       (GimpItem               *item,
+                                          GimpTransformResize     clip_result);
+  gboolean        (* fill)               (GimpItem               *item,
+                                          GimpDrawable           *drawable,
+                                          GimpFillOptions        *fill_options,
+                                          gboolean                push_undo,
+                                          GimpProgress           *progress,
+                                          GError                **error);
+  gboolean        (* stroke)             (GimpItem               *item,
+                                          GimpDrawable           *drawable,
+                                          GimpStrokeOptions      *stroke_options,
+                                          gboolean                push_undo,
+                                          GimpProgress           *progress,
+                                          GError                **error);
+  void            (* to_selection)       (GimpItem               *item,
+                                          GimpChannelOps          op,
+                                          gboolean                antialias,
+                                          gboolean                feather,
+                                          gdouble                 feather_radius_x,
+                                          gdouble                 feather_radius_y);
+
+  const gchar *default_name;
+  const gchar *rename_desc;
+  const gchar *translate_desc;
+  const gchar *scale_desc;
+  const gchar *resize_desc;
+  const gchar *flip_desc;
+  const gchar *rotate_desc;
+  const gchar *transform_desc;
+  const gchar *to_selection_desc;
+  const gchar *fill_desc;
+  const gchar *stroke_desc;
+
+  const gchar *reorder_desc;
+  const gchar *raise_desc;
+  const gchar *raise_to_top_desc;
+  const gchar *lower_desc;
+  const gchar *lower_to_bottom_desc;
+
+  const gchar *raise_failed;
+  const gchar *lower_failed;
+};
+
+
+GType           gimp_item_get_type           (void) G_GNUC_CONST;
+
+GimpItem      * gimp_item_new                (GType               type,
+                                              GimpImage          *image,
+                                              const gchar        *name,
+                                              gint                offset_x,
+                                              gint                offset_y,
+                                              gint                width,
+                                              gint                height);
+
+void            gimp_item_removed            (GimpItem           *item);
+gboolean        gimp_item_is_removed         (GimpItem           *item);
+void            gimp_item_unset_removed      (GimpItem           *item);
+
+gboolean        gimp_item_is_attached        (GimpItem           *item);
+
+GimpItem      * gimp_item_get_parent         (GimpItem           *item);
+
+GimpItemTree  * gimp_item_get_tree           (GimpItem           *item);
+GimpContainer * gimp_item_get_container      (GimpItem           *item);
+GList         * gimp_item_get_container_iter (GimpItem           *item);
+gint            gimp_item_get_index          (GimpItem           *item);
+GList         * gimp_item_get_path           (GimpItem           *item);
+
+gboolean        gimp_item_bounds             (GimpItem           *item,
+                                              gint               *x,
+                                              gint               *y,
+                                              gint               *width,
+                                              gint               *height);
+gboolean        gimp_item_bounds_f           (GimpItem           *item,
+                                              gdouble            *x,
+                                              gdouble            *y,
+                                              gdouble            *width,
+                                              gdouble            *height);
+
+GimpItem      * gimp_item_duplicate          (GimpItem           *item,
+                                              GType               new_type);
+GimpItem      * gimp_item_convert            (GimpItem           *item,
+                                              GimpImage          *dest_image,
+                                              GType               new_type);
+
+gboolean        gimp_item_rename             (GimpItem           *item,
+                                              const gchar        *new_name,
+                                              GError            **error);
+
+gint            gimp_item_get_width          (GimpItem           *item);
+gint            gimp_item_get_height         (GimpItem           *item);
+void            gimp_item_set_size           (GimpItem           *item,
+                                              gint                width,
+                                              gint                height);
+
+void            gimp_item_get_offset         (GimpItem           *item,
+                                              gint               *offset_x,
+                                              gint               *offset_y);
+void            gimp_item_set_offset         (GimpItem           *item,
+                                              gint                offset_x,
+                                              gint                offset_y);
+gint            gimp_item_get_offset_x       (GimpItem           *item);
+gint            gimp_item_get_offset_y       (GimpItem           *item);
+
+void            gimp_item_start_move         (GimpItem           *item,
+                                              gboolean            push_undo);
+void            gimp_item_end_move           (GimpItem           *item,
+                                              gboolean            push_undo);
+
+void            gimp_item_start_transform    (GimpItem           *item,
+                                              gboolean            push_undo);
+void            gimp_item_end_transform      (GimpItem           *item,
+                                              gboolean            push_undo);
+
+void            gimp_item_translate          (GimpItem           *item,
+                                              gdouble             offset_x,
+                                              gdouble             offset_y,
+                                              gboolean            push_undo);
+
+gboolean        gimp_item_check_scaling      (GimpItem           *item,
+                                              gint                new_width,
+                                              gint                new_height);
+void            gimp_item_scale              (GimpItem           *item,
+                                              gint                new_width,
+                                              gint                new_height,
+                                              gint                new_offset_x,
+                                              gint                new_offset_y,
+                                              GimpInterpolationType interpolation,
+                                              GimpProgress       *progress);
+gboolean        gimp_item_scale_by_factors   (GimpItem           *item,
+                                              gdouble             w_factor,
+                                              gdouble             h_factor,
+                                              GimpInterpolationType interpolation,
+                                              GimpProgress       *progress);
+gboolean
+      gimp_item_scale_by_factors_with_origin (GimpItem           *item,
+                                              gdouble             w_factor,
+                                              gdouble             h_factor,
+                                              gint                origin_x,
+                                              gint                origin_y,
+                                              gint                new_origin_x,
+                                              gint                new_origin_y,
+                                              GimpInterpolationType interpolation,
+                                              GimpProgress       *progress);
+void            gimp_item_scale_by_origin    (GimpItem           *item,
+                                              gint                new_width,
+                                              gint                new_height,
+                                              GimpInterpolationType interpolation,
+                                              GimpProgress       *progress,
+                                              gboolean            local_origin);
+void            gimp_item_resize             (GimpItem           *item,
+                                              GimpContext        *context,
+                                              GimpFillType        fill_type,
+                                              gint                new_width,
+                                              gint                new_height,
+                                              gint                offset_x,
+                                              gint                offset_y);
+void            gimp_item_resize_to_image    (GimpItem           *item);
+
+void            gimp_item_flip               (GimpItem           *item,
+                                              GimpContext        *context,
+                                              GimpOrientationType flip_type,
+                                              gdouble             axis,
+                                              gboolean            clip_result);
+void            gimp_item_rotate             (GimpItem           *item,
+                                              GimpContext        *context,
+                                              GimpRotationType    rotate_type,
+                                              gdouble             center_x,
+                                              gdouble             center_y,
+                                              gboolean            clip_result);
+void            gimp_item_transform          (GimpItem           *item,
+                                              GimpContext        *context,
+                                              const GimpMatrix3  *matrix,
+                                              GimpTransformDirection direction,
+                                              GimpInterpolationType interpolation_type,
+                                              GimpTransformResize clip_result,
+                                              GimpProgress       *progress);
+GimpTransformResize   gimp_item_get_clip     (GimpItem           *item,
+                                              GimpTransformResize clip_result);
+
+gboolean        gimp_item_fill               (GimpItem           *item,
+                                              GimpDrawable       *drawable,
+                                              GimpFillOptions    *fill_options,
+                                              gboolean            push_undo,
+                                              GimpProgress       *progress,
+                                              GError            **error);
+gboolean        gimp_item_stroke             (GimpItem           *item,
+                                              GimpDrawable       *drawable,
+                                              GimpContext        *context,
+                                              GimpStrokeOptions  *stroke_options,
+                                              GimpPaintOptions   *paint_options,
+                                              gboolean            push_undo,
+                                              GimpProgress       *progress,
+                                              GError            **error);
+
+void            gimp_item_to_selection       (GimpItem           *item,
+                                              GimpChannelOps      op,
+                                              gboolean            antialias,
+                                              gboolean            feather,
+                                              gdouble             feather_radius_x,
+                                              gdouble             feather_radius_y);
+
+void            gimp_item_add_offset_node    (GimpItem           *item,
+                                              GeglNode           *node);
+void            gimp_item_remove_offset_node (GimpItem           *item,
+                                              GeglNode           *node);
+
+gint            gimp_item_get_ID             (GimpItem           *item);
+GimpItem      * gimp_item_get_by_ID          (Gimp               *gimp,
+                                              gint                id);
+
+GimpTattoo      gimp_item_get_tattoo         (GimpItem           *item);
+void            gimp_item_set_tattoo         (GimpItem           *item,
+                                              GimpTattoo          tattoo);
+
+GimpImage     * gimp_item_get_image          (GimpItem           *item);
+void            gimp_item_set_image          (GimpItem           *item,
+                                              GimpImage          *image);
+
+void            gimp_item_replace_item       (GimpItem           *item,
+                                              GimpItem           *replace);
+
+void               gimp_item_set_parasites   (GimpItem           *item,
+                                              GimpParasiteList   *parasites);
+GimpParasiteList * gimp_item_get_parasites   (GimpItem           *item);
+
+gboolean        gimp_item_parasite_validate  (GimpItem           *item,
+                                              const GimpParasite *parasite,
+                                              GError            **error);
+void            gimp_item_parasite_attach    (GimpItem           *item,
+                                              const GimpParasite *parasite,
+                                              gboolean            push_undo);
+void            gimp_item_parasite_detach    (GimpItem           *item,
+                                              const gchar        *name,
+                                              gboolean            push_undo);
+const GimpParasite * gimp_item_parasite_find (GimpItem           *item,
+                                              const gchar        *name);
+gchar        ** gimp_item_parasite_list      (GimpItem           *item,
+                                              gint               *count);
+
+void            gimp_item_set_visible        (GimpItem           *item,
+                                              gboolean            visible,
+                                              gboolean            push_undo);
+gboolean        gimp_item_get_visible        (GimpItem           *item);
+gboolean        gimp_item_is_visible         (GimpItem           *item);
+
+void        gimp_item_bind_visible_to_active (GimpItem           *item,
+                                              gboolean            bind);
+
+void            gimp_item_set_linked         (GimpItem           *item,
+                                              gboolean            linked,
+                                              gboolean            push_undo);
+gboolean        gimp_item_get_linked         (GimpItem           *item);
+
+void            gimp_item_set_color_tag      (GimpItem           *item,
+                                              GimpColorTag        color_tag,
+                                              gboolean            push_undo);
+GimpColorTag    gimp_item_get_color_tag      (GimpItem           *item);
+GimpColorTag  gimp_item_get_merged_color_tag (GimpItem           *item);
+
+void            gimp_item_set_lock_content   (GimpItem           *item,
+                                              gboolean            lock_content,
+                                              gboolean            push_undo);
+gboolean        gimp_item_get_lock_content   (GimpItem           *item);
+gboolean        gimp_item_can_lock_content   (GimpItem           *item);
+gboolean        gimp_item_is_content_locked  (GimpItem           *item);
+
+void            gimp_item_set_lock_position  (GimpItem          *item,
+                                              gboolean           lock_position,
+                                              gboolean           push_undo);
+gboolean        gimp_item_get_lock_position  (GimpItem          *item);
+gboolean        gimp_item_can_lock_position  (GimpItem          *item);
+gboolean        gimp_item_is_position_locked (GimpItem          *item);
+
+gboolean        gimp_item_mask_bounds        (GimpItem           *item,
+                                              gint               *x1,
+                                              gint               *y1,
+                                              gint               *x2,
+                                              gint               *y2);
+gboolean        gimp_item_mask_intersect     (GimpItem           *item,
+                                              gint               *x,
+                                              gint               *y,
+                                              gint               *width,
+                                              gint               *height);
+
+gboolean        gimp_item_is_in_set          (GimpItem           *item,
+                                              GimpItemSet         set);
+
+
+#endif /* __GIMP_ITEM_H__ */
diff --git a/app/core/gimpitempropundo.c b/app/core/gimpitempropundo.c
new file mode 100644
index 0000000..241b8aa
--- /dev/null
+++ b/app/core/gimpitempropundo.c
@@ -0,0 +1,358 @@
+/* Gimp - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+
+#include "core-types.h"
+
+#include "gimp-memsize.h"
+#include "gimpitem.h"
+#include "gimpitemtree.h"
+#include "gimpitempropundo.h"
+#include "gimpparasitelist.h"
+
+
+enum
+{
+  PROP_0,
+  PROP_PARASITE_NAME
+};
+
+
+static void     gimp_item_prop_undo_constructed  (GObject             *object);
+static void     gimp_item_prop_undo_set_property (GObject             *object,
+                                                  guint                property_id,
+                                                  const GValue        *value,
+                                                  GParamSpec          *pspec);
+static void     gimp_item_prop_undo_get_property (GObject             *object,
+                                                  guint                property_id,
+                                                  GValue              *value,
+                                                  GParamSpec          *pspec);
+
+static gint64   gimp_item_prop_undo_get_memsize  (GimpObject          *object,
+                                                  gint64              *gui_size);
+
+static void     gimp_item_prop_undo_pop          (GimpUndo            *undo,
+                                                  GimpUndoMode         undo_mode,
+                                                  GimpUndoAccumulator *accum);
+static void     gimp_item_prop_undo_free         (GimpUndo            *undo,
+                                                  GimpUndoMode         undo_mode);
+
+
+G_DEFINE_TYPE (GimpItemPropUndo, gimp_item_prop_undo, GIMP_TYPE_ITEM_UNDO)
+
+#define parent_class gimp_item_prop_undo_parent_class
+
+
+static void
+gimp_item_prop_undo_class_init (GimpItemPropUndoClass *klass)
+{
+  GObjectClass    *object_class      = G_OBJECT_CLASS (klass);
+  GimpObjectClass *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+  GimpUndoClass   *undo_class        = GIMP_UNDO_CLASS (klass);
+
+  object_class->constructed      = gimp_item_prop_undo_constructed;
+  object_class->set_property     = gimp_item_prop_undo_set_property;
+  object_class->get_property     = gimp_item_prop_undo_get_property;
+
+  gimp_object_class->get_memsize = gimp_item_prop_undo_get_memsize;
+
+  undo_class->pop                = gimp_item_prop_undo_pop;
+  undo_class->free               = gimp_item_prop_undo_free;
+
+  g_object_class_install_property (object_class, PROP_PARASITE_NAME,
+                                   g_param_spec_string ("parasite-name",
+                                                        NULL, NULL,
+                                                        NULL,
+                                                        GIMP_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT_ONLY));
+}
+
+static void
+gimp_item_prop_undo_init (GimpItemPropUndo *undo)
+{
+}
+
+static void
+gimp_item_prop_undo_constructed (GObject *object)
+{
+  GimpItemPropUndo *item_prop_undo = GIMP_ITEM_PROP_UNDO (object);
+  GimpItem         *item;
+
+  G_OBJECT_CLASS (parent_class)->constructed (object);
+
+  item = GIMP_ITEM_UNDO (object)->item;
+
+  switch (GIMP_UNDO (object)->undo_type)
+    {
+    case GIMP_UNDO_ITEM_REORDER:
+      item_prop_undo->parent   = gimp_item_get_parent (item);
+      item_prop_undo->position = gimp_item_get_index (item);
+      break;
+
+    case GIMP_UNDO_ITEM_RENAME:
+      item_prop_undo->name = g_strdup (gimp_object_get_name (item));
+      break;
+
+    case GIMP_UNDO_ITEM_DISPLACE:
+      gimp_item_get_offset (item,
+                            &item_prop_undo->offset_x,
+                            &item_prop_undo->offset_y);
+      break;
+
+    case GIMP_UNDO_ITEM_VISIBILITY:
+      item_prop_undo->visible = gimp_item_get_visible (item);
+      break;
+
+    case GIMP_UNDO_ITEM_LINKED:
+      item_prop_undo->linked = gimp_item_get_linked (item);
+      break;
+
+    case GIMP_UNDO_ITEM_COLOR_TAG:
+      item_prop_undo->color_tag = gimp_item_get_color_tag (item);
+      break;
+
+    case GIMP_UNDO_ITEM_LOCK_CONTENT:
+      item_prop_undo->lock_content = gimp_item_get_lock_content (item);
+      break;
+
+    case GIMP_UNDO_ITEM_LOCK_POSITION:
+      item_prop_undo->lock_position = gimp_item_get_lock_position (item);
+      break;
+
+    case GIMP_UNDO_PARASITE_ATTACH:
+    case GIMP_UNDO_PARASITE_REMOVE:
+      gimp_assert (item_prop_undo->parasite_name != NULL);
+
+      item_prop_undo->parasite = gimp_parasite_copy
+        (gimp_item_parasite_find (item, item_prop_undo->parasite_name));
+      break;
+
+    default:
+      g_return_if_reached ();
+    }
+}
+
+static void
+gimp_item_prop_undo_set_property (GObject      *object,
+                                  guint         property_id,
+                                  const GValue *value,
+                                  GParamSpec   *pspec)
+{
+  GimpItemPropUndo *item_prop_undo = GIMP_ITEM_PROP_UNDO (object);
+
+  switch (property_id)
+    {
+    case PROP_PARASITE_NAME:
+      item_prop_undo->parasite_name = g_value_dup_string (value);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_item_prop_undo_get_property (GObject    *object,
+                                  guint       property_id,
+                                  GValue     *value,
+                                  GParamSpec *pspec)
+{
+  GimpItemPropUndo *item_prop_undo = GIMP_ITEM_PROP_UNDO (object);
+
+  switch (property_id)
+    {
+    case PROP_PARASITE_NAME:
+      g_value_set_string (value, item_prop_undo->parasite_name);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static gint64
+gimp_item_prop_undo_get_memsize (GimpObject *object,
+                                 gint64     *gui_size)
+{
+  GimpItemPropUndo *item_prop_undo = GIMP_ITEM_PROP_UNDO (object);
+  gint64            memsize        = 0;
+
+  memsize += gimp_string_get_memsize (item_prop_undo->name);
+  memsize += gimp_string_get_memsize (item_prop_undo->parasite_name);
+  memsize += gimp_parasite_get_memsize (item_prop_undo->parasite, NULL);
+
+  return memsize + GIMP_OBJECT_CLASS (parent_class)->get_memsize (object,
+                                                                  gui_size);
+}
+
+static void
+gimp_item_prop_undo_pop (GimpUndo            *undo,
+                         GimpUndoMode         undo_mode,
+                         GimpUndoAccumulator *accum)
+{
+  GimpItemPropUndo *item_prop_undo = GIMP_ITEM_PROP_UNDO (undo);
+  GimpItem         *item           = GIMP_ITEM_UNDO (undo)->item;
+
+  GIMP_UNDO_CLASS (parent_class)->pop (undo, undo_mode, accum);
+
+  switch (undo->undo_type)
+    {
+    case GIMP_UNDO_ITEM_REORDER:
+      {
+        GimpItem *parent;
+        gint      position;
+
+        parent   = gimp_item_get_parent (item);
+        position = gimp_item_get_index (item);
+
+        gimp_item_tree_reorder_item (gimp_item_get_tree (item), item,
+                                     item_prop_undo->parent,
+                                     item_prop_undo->position,
+                                     FALSE, NULL);
+
+        item_prop_undo->parent   = parent;
+        item_prop_undo->position = position;
+      }
+      break;
+
+    case GIMP_UNDO_ITEM_RENAME:
+      {
+        gchar *name;
+
+        name = g_strdup (gimp_object_get_name (item));
+
+        gimp_item_tree_rename_item (gimp_item_get_tree (item), item,
+                                    item_prop_undo->name,
+                                    FALSE, NULL);
+
+        g_free (item_prop_undo->name);
+        item_prop_undo->name = name;
+      }
+      break;
+
+    case GIMP_UNDO_ITEM_DISPLACE:
+      {
+        gint offset_x;
+        gint offset_y;
+
+        gimp_item_get_offset (item, &offset_x, &offset_y);
+
+        gimp_item_translate (item,
+                             item_prop_undo->offset_x - offset_x,
+                             item_prop_undo->offset_y - offset_y,
+                             FALSE);
+
+        item_prop_undo->offset_x = offset_x;
+        item_prop_undo->offset_y = offset_y;
+      }
+      break;
+
+    case GIMP_UNDO_ITEM_VISIBILITY:
+      {
+        gboolean visible;
+
+        visible = gimp_item_get_visible (item);
+        gimp_item_set_visible (item, item_prop_undo->visible, FALSE);
+        item_prop_undo->visible = visible;
+      }
+      break;
+
+    case GIMP_UNDO_ITEM_LINKED:
+      {
+        gboolean linked;
+
+        linked = gimp_item_get_linked (item);
+        gimp_item_set_linked (item, item_prop_undo->linked, FALSE);
+        item_prop_undo->linked = linked;
+      }
+      break;
+
+    case GIMP_UNDO_ITEM_COLOR_TAG:
+      {
+        GimpColorTag color_tag;
+
+        color_tag = gimp_item_get_color_tag (item);
+        gimp_item_set_color_tag (item, item_prop_undo->color_tag, FALSE);
+        item_prop_undo->color_tag = color_tag;
+      }
+      break;
+
+    case GIMP_UNDO_ITEM_LOCK_CONTENT:
+      {
+        gboolean lock_content;
+
+        lock_content = gimp_item_get_lock_content (item);
+        gimp_item_set_lock_content (item, item_prop_undo->lock_content, FALSE);
+        item_prop_undo->lock_content = lock_content;
+      }
+      break;
+
+    case GIMP_UNDO_ITEM_LOCK_POSITION:
+      {
+        gboolean lock_position;
+
+        lock_position = gimp_item_get_lock_position (item);
+        gimp_item_set_lock_position (item, item_prop_undo->lock_position, FALSE);
+        item_prop_undo->lock_position = lock_position;
+      }
+      break;
+
+    case GIMP_UNDO_PARASITE_ATTACH:
+    case GIMP_UNDO_PARASITE_REMOVE:
+      {
+        GimpParasite *parasite;
+
+        parasite = item_prop_undo->parasite;
+
+        item_prop_undo->parasite = gimp_parasite_copy
+          (gimp_item_parasite_find (item, item_prop_undo->parasite_name));
+
+        if (parasite)
+          gimp_item_parasite_attach (item, parasite, FALSE);
+        else
+          gimp_item_parasite_detach (item, item_prop_undo->parasite_name, FALSE);
+
+        if (parasite)
+          gimp_parasite_free (parasite);
+      }
+      break;
+
+    default:
+      g_return_if_reached ();
+    }
+}
+
+static void
+gimp_item_prop_undo_free (GimpUndo     *undo,
+                          GimpUndoMode  undo_mode)
+{
+  GimpItemPropUndo *item_prop_undo = GIMP_ITEM_PROP_UNDO (undo);
+
+  g_clear_pointer (&item_prop_undo->name,          g_free);
+  g_clear_pointer (&item_prop_undo->parasite_name, g_free);
+  g_clear_pointer (&item_prop_undo->parasite,      gimp_parasite_free);
+
+  GIMP_UNDO_CLASS (parent_class)->free (undo, undo_mode);
+}
diff --git a/app/core/gimpitempropundo.h b/app/core/gimpitempropundo.h
new file mode 100644
index 0000000..8f96e46
--- /dev/null
+++ b/app/core/gimpitempropundo.h
@@ -0,0 +1,63 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_ITEM_PROP_UNDO_H__
+#define __GIMP_ITEM_PROP_UNDO_H__
+
+
+#include "gimpitemundo.h"
+
+
+#define GIMP_TYPE_ITEM_PROP_UNDO            (gimp_item_prop_undo_get_type ())
+#define GIMP_ITEM_PROP_UNDO(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_ITEM_PROP_UNDO, GimpItemPropUndo))
+#define GIMP_ITEM_PROP_UNDO_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_ITEM_PROP_UNDO, GimpItemPropUndoClass))
+#define GIMP_IS_ITEM_PROP_UNDO(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_ITEM_PROP_UNDO))
+#define GIMP_IS_ITEM_PROP_UNDO_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_ITEM_PROP_UNDO))
+#define GIMP_ITEM_PROP_UNDO_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_ITEM_PROP_UNDO, GimpItemPropUndoClass))
+
+
+typedef struct _GimpItemPropUndo      GimpItemPropUndo;
+typedef struct _GimpItemPropUndoClass GimpItemPropUndoClass;
+
+struct _GimpItemPropUndo
+{
+  GimpItemUndo  parent_instance;
+
+  GimpItem     *parent;
+  gint          position;
+  gchar        *name;
+  gint          offset_x;
+  gint          offset_y;
+  guint         visible       : 1;
+  guint         linked        : 1;
+  guint         lock_content  : 1;
+  guint         lock_position : 1;
+  GimpColorTag  color_tag;
+  gchar        *parasite_name;
+  GimpParasite *parasite;
+};
+
+struct _GimpItemPropUndoClass
+{
+  GimpItemUndoClass  parent_class;
+};
+
+
+GType   gimp_item_prop_undo_get_type (void) G_GNUC_CONST;
+
+
+#endif /* __GIMP_ITEM_PROP_UNDO_H__ */
diff --git a/app/core/gimpitemstack.c b/app/core/gimpitemstack.c
new file mode 100644
index 0000000..c7f2fe1
--- /dev/null
+++ b/app/core/gimpitemstack.c
@@ -0,0 +1,348 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1997 Spencer Kimball and Peter Mattis
+ *
+ * gimpitemstack.c
+ * Copyright (C) 2008 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <cairo.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpcolor/gimpcolor.h"
+
+#include "core-types.h"
+
+#include "gimpitem.h"
+#include "gimpitemstack.h"
+
+
+/*  local function prototypes  */
+
+static void   gimp_item_stack_constructed (GObject       *object);
+
+static void   gimp_item_stack_add         (GimpContainer *container,
+                                           GimpObject    *object);
+static void   gimp_item_stack_remove      (GimpContainer *container,
+                                           GimpObject    *object);
+
+
+G_DEFINE_TYPE (GimpItemStack, gimp_item_stack, GIMP_TYPE_FILTER_STACK)
+
+#define parent_class gimp_item_stack_parent_class
+
+
+static void
+gimp_item_stack_class_init (GimpItemStackClass *klass)
+{
+  GObjectClass       *object_class    = G_OBJECT_CLASS (klass);
+  GimpContainerClass *container_class = GIMP_CONTAINER_CLASS (klass);
+
+  object_class->constructed = gimp_item_stack_constructed;
+
+  container_class->add      = gimp_item_stack_add;
+  container_class->remove   = gimp_item_stack_remove;
+}
+
+static void
+gimp_item_stack_init (GimpItemStack *stack)
+{
+}
+
+static void
+gimp_item_stack_constructed (GObject *object)
+{
+  GimpContainer *container = GIMP_CONTAINER (object);
+
+  G_OBJECT_CLASS (parent_class)->constructed (object);
+
+  gimp_assert (g_type_is_a (gimp_container_get_children_type (container),
+                         GIMP_TYPE_ITEM));
+}
+
+static void
+gimp_item_stack_add (GimpContainer *container,
+                     GimpObject    *object)
+{
+  g_object_ref_sink (object);
+
+  GIMP_CONTAINER_CLASS (parent_class)->add (container, object);
+
+  g_object_unref (object);
+}
+
+static void
+gimp_item_stack_remove (GimpContainer *container,
+                        GimpObject    *object)
+{
+  GIMP_CONTAINER_CLASS (parent_class)->remove (container, object);
+}
+
+
+/*  public functions  */
+
+GimpContainer *
+gimp_item_stack_new (GType item_type)
+{
+  g_return_val_if_fail (g_type_is_a (item_type, GIMP_TYPE_ITEM), NULL);
+
+  return g_object_new (GIMP_TYPE_ITEM_STACK,
+                       "name",          g_type_name (item_type),
+                       "children-type", item_type,
+                       "policy",        GIMP_CONTAINER_POLICY_STRONG,
+                       NULL);
+}
+
+gint
+gimp_item_stack_get_n_items (GimpItemStack *stack)
+{
+  GList *list;
+  gint   n_items = 0;
+
+  g_return_val_if_fail (GIMP_IS_ITEM_STACK (stack), 0);
+
+  for (list = GIMP_LIST (stack)->queue->head; list; list = g_list_next (list))
+    {
+      GimpItem      *item = list->data;
+      GimpContainer *children;
+
+      n_items++;
+
+      children = gimp_viewable_get_children (GIMP_VIEWABLE (item));
+
+      if (children)
+        n_items += gimp_item_stack_get_n_items (GIMP_ITEM_STACK (children));
+    }
+
+  return n_items;
+}
+
+gboolean
+gimp_item_stack_is_flat (GimpItemStack *stack)
+{
+  GList *list;
+
+  g_return_val_if_fail (GIMP_IS_ITEM_STACK (stack), TRUE);
+
+  for (list = GIMP_LIST (stack)->queue->head; list; list = g_list_next (list))
+    {
+      GimpViewable *viewable = list->data;
+
+      if (gimp_viewable_get_children (viewable))
+        return FALSE;
+    }
+
+  return TRUE;
+}
+
+GList *
+gimp_item_stack_get_item_iter (GimpItemStack *stack)
+{
+  g_return_val_if_fail (GIMP_IS_ITEM_STACK (stack), NULL);
+
+  return GIMP_LIST (stack)->queue->head;
+}
+
+GList *
+gimp_item_stack_get_item_list (GimpItemStack *stack)
+{
+  GList *list;
+  GList *result = NULL;
+
+  g_return_val_if_fail (GIMP_IS_ITEM_STACK (stack), NULL);
+
+  for (list = GIMP_LIST (stack)->queue->head;
+       list;
+       list = g_list_next (list))
+    {
+      GimpViewable  *viewable = list->data;
+      GimpContainer *children;
+
+      result = g_list_prepend (result, viewable);
+
+      children = gimp_viewable_get_children (viewable);
+
+      if (children)
+        {
+          GList *child_list;
+
+          child_list = gimp_item_stack_get_item_list (GIMP_ITEM_STACK (children));
+
+          while (child_list)
+            {
+              result = g_list_prepend (result, child_list->data);
+
+              child_list = g_list_remove (child_list, child_list->data);
+            }
+        }
+    }
+
+  return g_list_reverse (result);
+}
+
+GimpItem *
+gimp_item_stack_get_item_by_tattoo (GimpItemStack *stack,
+                                    GimpTattoo     tattoo)
+{
+  GList *list;
+
+  g_return_val_if_fail (GIMP_IS_ITEM_STACK (stack), NULL);
+
+  for (list = GIMP_LIST (stack)->queue->head; list; list = g_list_next (list))
+    {
+      GimpItem      *item = list->data;
+      GimpContainer *children;
+
+      if (gimp_item_get_tattoo (item) == tattoo)
+        return item;
+
+      children = gimp_viewable_get_children (GIMP_VIEWABLE (item));
+
+      if (children)
+        {
+          item = gimp_item_stack_get_item_by_tattoo (GIMP_ITEM_STACK (children),
+                                                     tattoo);
+
+          if (item)
+            return item;
+        }
+    }
+
+  return NULL;
+}
+
+GimpItem *
+gimp_item_stack_get_item_by_path (GimpItemStack *stack,
+                                  GList         *path)
+{
+  GimpContainer *container;
+  GimpItem      *item = NULL;
+
+  g_return_val_if_fail (GIMP_IS_ITEM_STACK (stack), NULL);
+  g_return_val_if_fail (path != NULL, NULL);
+
+  container = GIMP_CONTAINER (stack);
+
+  while (path)
+    {
+      guint32 i = GPOINTER_TO_UINT (path->data);
+
+      item = GIMP_ITEM (gimp_container_get_child_by_index (container, i));
+
+      g_return_val_if_fail (GIMP_IS_ITEM (item), item);
+
+      if (path->next)
+        {
+          container = gimp_viewable_get_children (GIMP_VIEWABLE (item));
+
+          g_return_val_if_fail (GIMP_IS_ITEM_STACK (container), item);
+        }
+
+      path = path->next;
+    }
+
+  return item;
+}
+
+GimpItem *
+gimp_item_stack_get_parent_by_path (GimpItemStack *stack,
+                                    GList         *path,
+                                    gint          *index)
+{
+  GimpItem *parent = NULL;
+  guint32   i;
+
+  g_return_val_if_fail (GIMP_IS_ITEM_STACK (stack), NULL);
+  g_return_val_if_fail (path != NULL, NULL);
+
+  i = GPOINTER_TO_UINT (path->data);
+
+  if (index)
+    *index = i;
+
+  while (path->next)
+    {
+      GimpObject    *child;
+      GimpContainer *children;
+
+      child = gimp_container_get_child_by_index (GIMP_CONTAINER (stack), i);
+
+      g_return_val_if_fail (GIMP_IS_ITEM (child), parent);
+
+      children = gimp_viewable_get_children (GIMP_VIEWABLE (child));
+
+      g_return_val_if_fail (GIMP_IS_ITEM_STACK (children), parent);
+
+      parent = GIMP_ITEM (child);
+      stack  = GIMP_ITEM_STACK (children);
+
+      path = path->next;
+
+      i = GPOINTER_TO_UINT (path->data);
+
+      if (index)
+        *index = i;
+    }
+
+  return parent;
+}
+
+static void
+gimp_item_stack_viewable_invalidate_previews (GimpViewable *viewable)
+{
+  GimpContainer *children = gimp_viewable_get_children (viewable);
+
+  if (children)
+    gimp_item_stack_invalidate_previews (GIMP_ITEM_STACK (children));
+
+  gimp_viewable_invalidate_preview (viewable);
+}
+
+void
+gimp_item_stack_invalidate_previews (GimpItemStack *stack)
+{
+  g_return_if_fail (GIMP_IS_ITEM_STACK (stack));
+
+  gimp_container_foreach (GIMP_CONTAINER (stack),
+                          (GFunc) gimp_item_stack_viewable_invalidate_previews,
+                          NULL);
+}
+
+static void
+gimp_item_stack_viewable_profile_changed (GimpViewable *viewable)
+{
+  GimpContainer *children = gimp_viewable_get_children (viewable);
+
+  if (children)
+    gimp_item_stack_profile_changed (GIMP_ITEM_STACK (children));
+
+  if (GIMP_IS_COLOR_MANAGED (viewable))
+    gimp_color_managed_profile_changed (GIMP_COLOR_MANAGED (viewable));
+}
+
+void
+gimp_item_stack_profile_changed (GimpItemStack *stack)
+{
+  g_return_if_fail (GIMP_IS_ITEM_STACK (stack));
+
+  gimp_container_foreach (GIMP_CONTAINER (stack),
+                          (GFunc) gimp_item_stack_viewable_profile_changed,
+                          NULL);
+}
diff --git a/app/core/gimpitemstack.h b/app/core/gimpitemstack.h
new file mode 100644
index 0000000..b476076
--- /dev/null
+++ b/app/core/gimpitemstack.h
@@ -0,0 +1,66 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1997 Spencer Kimball and Peter Mattis
+ *
+ * gimpitemstack.h
+ * Copyright (C) 2008 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_ITEM_STACK_H__
+#define __GIMP_ITEM_STACK_H__
+
+#include "gimpfilterstack.h"
+
+
+#define GIMP_TYPE_ITEM_STACK            (gimp_item_stack_get_type ())
+#define GIMP_ITEM_STACK(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_ITEM_STACK, GimpItemStack))
+#define GIMP_ITEM_STACK_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_ITEM_STACK, GimpItemStackClass))
+#define GIMP_IS_ITEM_STACK(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_ITEM_STACK))
+#define GIMP_IS_ITEM_STACK_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_ITEM_STACK))
+
+
+typedef struct _GimpItemStackClass GimpItemStackClass;
+
+struct _GimpItemStack
+{
+  GimpFilterStack  parent_instance;
+};
+
+struct _GimpItemStackClass
+{
+  GimpFilterStackClass  parent_class;
+};
+
+
+GType           gimp_item_stack_get_type            (void) G_GNUC_CONST;
+GimpContainer * gimp_item_stack_new                 (GType          item_type);
+
+gint            gimp_item_stack_get_n_items         (GimpItemStack *stack);
+gboolean        gimp_item_stack_is_flat             (GimpItemStack *stack);
+GList         * gimp_item_stack_get_item_iter       (GimpItemStack *stack);
+GList         * gimp_item_stack_get_item_list       (GimpItemStack *stack);
+GimpItem      * gimp_item_stack_get_item_by_tattoo  (GimpItemStack *stack,
+                                                     GimpTattoo     tattoo);
+GimpItem      * gimp_item_stack_get_item_by_path    (GimpItemStack *stack,
+                                                     GList         *path);
+GimpItem      * gimp_item_stack_get_parent_by_path  (GimpItemStack *stack,
+                                                     GList         *path,
+                                                     gint          *index);
+
+void            gimp_item_stack_invalidate_previews (GimpItemStack *stack);
+void            gimp_item_stack_profile_changed     (GimpItemStack *stack);
+
+
+#endif  /*  __GIMP_ITEM_STACK_H__  */
diff --git a/app/core/gimpitemtree.c b/app/core/gimpitemtree.c
new file mode 100644
index 0000000..7746afa
--- /dev/null
+++ b/app/core/gimpitemtree.c
@@ -0,0 +1,714 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1997 Spencer Kimball and Peter Mattis
+ *
+ * gimpitemtree.c
+ * Copyright (C) 2010 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gimpimage.h"
+#include "gimpimage-undo-push.h"
+#include "gimpitem.h"
+#include "gimpitemstack.h"
+#include "gimpitemtree.h"
+
+
+enum
+{
+  PROP_0,
+  PROP_IMAGE,
+  PROP_CONTAINER_TYPE,
+  PROP_ITEM_TYPE,
+  PROP_ACTIVE_ITEM
+};
+
+
+typedef struct _GimpItemTreePrivate GimpItemTreePrivate;
+
+struct _GimpItemTreePrivate
+{
+  GimpImage  *image;
+
+  GType       container_type;
+  GType       item_type;
+
+  GimpItem   *active_item;
+
+  GHashTable *name_hash;
+};
+
+#define GIMP_ITEM_TREE_GET_PRIVATE(object) \
+        ((GimpItemTreePrivate *) gimp_item_tree_get_instance_private ((GimpItemTree *) (object)))
+
+
+/*  local function prototypes  */
+
+static void     gimp_item_tree_constructed   (GObject      *object);
+static void     gimp_item_tree_dispose       (GObject      *object);
+static void     gimp_item_tree_finalize      (GObject      *object);
+static void     gimp_item_tree_set_property  (GObject      *object,
+                                              guint         property_id,
+                                              const GValue *value,
+                                              GParamSpec   *pspec);
+static void     gimp_item_tree_get_property  (GObject      *object,
+                                              guint         property_id,
+                                              GValue       *value,
+                                              GParamSpec   *pspec);
+
+static gint64   gimp_item_tree_get_memsize   (GimpObject   *object,
+                                              gint64       *gui_size);
+
+static void     gimp_item_tree_uniquefy_name (GimpItemTree *tree,
+                                              GimpItem     *item,
+                                              const gchar  *new_name);
+
+
+G_DEFINE_TYPE_WITH_PRIVATE (GimpItemTree, gimp_item_tree, GIMP_TYPE_OBJECT)
+
+#define parent_class gimp_item_tree_parent_class
+
+
+static void
+gimp_item_tree_class_init (GimpItemTreeClass *klass)
+{
+  GObjectClass    *object_class      = G_OBJECT_CLASS (klass);
+  GimpObjectClass *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+
+  object_class->constructed      = gimp_item_tree_constructed;
+  object_class->dispose          = gimp_item_tree_dispose;
+  object_class->finalize         = gimp_item_tree_finalize;
+  object_class->set_property     = gimp_item_tree_set_property;
+  object_class->get_property     = gimp_item_tree_get_property;
+
+  gimp_object_class->get_memsize = gimp_item_tree_get_memsize;
+
+  g_object_class_install_property (object_class, PROP_IMAGE,
+                                   g_param_spec_object ("image",
+                                                        NULL, NULL,
+                                                        GIMP_TYPE_IMAGE,
+                                                        GIMP_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT_ONLY));
+
+  g_object_class_install_property (object_class, PROP_CONTAINER_TYPE,
+                                   g_param_spec_gtype ("container-type",
+                                                       NULL, NULL,
+                                                       GIMP_TYPE_ITEM_STACK,
+                                                       GIMP_PARAM_READWRITE |
+                                                       G_PARAM_CONSTRUCT_ONLY));
+
+  g_object_class_install_property (object_class, PROP_ITEM_TYPE,
+                                   g_param_spec_gtype ("item-type",
+                                                       NULL, NULL,
+                                                       GIMP_TYPE_ITEM,
+                                                       GIMP_PARAM_READWRITE |
+                                                       G_PARAM_CONSTRUCT_ONLY));
+
+  g_object_class_install_property (object_class, PROP_ACTIVE_ITEM,
+                                   g_param_spec_object ("active-item",
+                                                        NULL, NULL,
+                                                        GIMP_TYPE_ITEM,
+                                                        GIMP_PARAM_READWRITE));
+}
+
+static void
+gimp_item_tree_init (GimpItemTree *tree)
+{
+  GimpItemTreePrivate *private = GIMP_ITEM_TREE_GET_PRIVATE (tree);
+
+  private->name_hash = g_hash_table_new (g_str_hash, g_str_equal);
+}
+
+static void
+gimp_item_tree_constructed (GObject *object)
+{
+  GimpItemTree        *tree    = GIMP_ITEM_TREE (object);
+  GimpItemTreePrivate *private = GIMP_ITEM_TREE_GET_PRIVATE (tree);
+
+  G_OBJECT_CLASS (parent_class)->constructed (object);
+
+  gimp_assert (GIMP_IS_IMAGE (private->image));
+  gimp_assert (g_type_is_a (private->container_type, GIMP_TYPE_ITEM_STACK));
+  gimp_assert (g_type_is_a (private->item_type,      GIMP_TYPE_ITEM));
+  gimp_assert (private->item_type != GIMP_TYPE_ITEM);
+
+  tree->container = g_object_new (private->container_type,
+                                  "name",          g_type_name (private->item_type),
+                                  "children-type", private->item_type,
+                                  "policy",        GIMP_CONTAINER_POLICY_STRONG,
+                                  NULL);
+}
+
+static void
+gimp_item_tree_dispose (GObject *object)
+{
+  GimpItemTree        *tree    = GIMP_ITEM_TREE (object);
+  GimpItemTreePrivate *private = GIMP_ITEM_TREE_GET_PRIVATE (tree);
+
+  gimp_item_tree_set_active_item (tree, NULL);
+
+  gimp_container_foreach (tree->container,
+                          (GFunc) gimp_item_removed, NULL);
+
+  gimp_container_clear (tree->container);
+  g_hash_table_remove_all (private->name_hash);
+
+  G_OBJECT_CLASS (parent_class)->dispose (object);
+}
+
+static void
+gimp_item_tree_finalize (GObject *object)
+{
+  GimpItemTree        *tree    = GIMP_ITEM_TREE (object);
+  GimpItemTreePrivate *private = GIMP_ITEM_TREE_GET_PRIVATE (tree);
+
+  g_clear_pointer (&private->name_hash, g_hash_table_unref);
+  g_clear_object (&tree->container);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gimp_item_tree_set_property (GObject      *object,
+                             guint         property_id,
+                             const GValue *value,
+                             GParamSpec   *pspec)
+{
+  GimpItemTreePrivate *private = GIMP_ITEM_TREE_GET_PRIVATE (object);
+
+  switch (property_id)
+    {
+    case PROP_IMAGE:
+      private->image = g_value_get_object (value); /* don't ref */
+      break;
+    case PROP_CONTAINER_TYPE:
+      private->container_type = g_value_get_gtype (value);
+      break;
+    case PROP_ITEM_TYPE:
+      private->item_type = g_value_get_gtype (value);
+      break;
+    case PROP_ACTIVE_ITEM:
+      private->active_item = g_value_get_object (value); /* don't ref */
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_item_tree_get_property (GObject    *object,
+                             guint       property_id,
+                             GValue     *value,
+                             GParamSpec *pspec)
+{
+  GimpItemTreePrivate *private = GIMP_ITEM_TREE_GET_PRIVATE (object);
+
+  switch (property_id)
+    {
+    case PROP_IMAGE:
+      g_value_set_object (value, private->image);
+      break;
+    case PROP_CONTAINER_TYPE:
+      g_value_set_gtype (value, private->container_type);
+      break;
+    case PROP_ITEM_TYPE:
+      g_value_set_gtype (value, private->item_type);
+      break;
+    case PROP_ACTIVE_ITEM:
+      g_value_set_object (value, private->active_item);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static gint64
+gimp_item_tree_get_memsize (GimpObject *object,
+                            gint64     *gui_size)
+{
+  GimpItemTree *tree    = GIMP_ITEM_TREE (object);
+  gint64        memsize = 0;
+
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (tree->container), gui_size);
+
+  return memsize + GIMP_OBJECT_CLASS (parent_class)->get_memsize (object,
+                                                                  gui_size);
+}
+
+
+/*  public functions  */
+
+GimpItemTree *
+gimp_item_tree_new (GimpImage *image,
+                    GType      container_type,
+                    GType      item_type)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (g_type_is_a (container_type, GIMP_TYPE_ITEM_STACK), NULL);
+  g_return_val_if_fail (g_type_is_a (item_type, GIMP_TYPE_ITEM), NULL);
+
+  return g_object_new (GIMP_TYPE_ITEM_TREE,
+                       "image",          image,
+                       "container-type", container_type,
+                       "item-type",      item_type,
+                       NULL);
+}
+
+GimpItem *
+gimp_item_tree_get_active_item (GimpItemTree *tree)
+{
+  g_return_val_if_fail (GIMP_IS_ITEM_TREE (tree), NULL);
+
+  return GIMP_ITEM_TREE_GET_PRIVATE (tree)->active_item;
+}
+
+void
+gimp_item_tree_set_active_item (GimpItemTree *tree,
+                                GimpItem     *item)
+{
+  GimpItemTreePrivate *private;
+
+  g_return_if_fail (GIMP_IS_ITEM_TREE (tree));
+
+  private = GIMP_ITEM_TREE_GET_PRIVATE (tree);
+
+  g_return_if_fail (item == NULL ||
+                    G_TYPE_CHECK_INSTANCE_TYPE (item, private->item_type));
+  g_return_if_fail (item == NULL || gimp_item_get_tree (item) == tree);
+
+  if (item != private->active_item)
+    {
+      private->active_item = item;
+
+      g_object_notify (G_OBJECT (tree), "active-item");
+    }
+}
+
+GimpItem *
+gimp_item_tree_get_item_by_name (GimpItemTree *tree,
+                                 const gchar  *name)
+{
+  g_return_val_if_fail (GIMP_IS_ITEM_TREE (tree), NULL);
+  g_return_val_if_fail (name != NULL, NULL);
+
+  return g_hash_table_lookup (GIMP_ITEM_TREE_GET_PRIVATE (tree)->name_hash,
+                              name);
+}
+
+gboolean
+gimp_item_tree_get_insert_pos (GimpItemTree  *tree,
+                               GimpItem      *item,
+                               GimpItem     **parent,
+                               gint          *position)
+{
+  GimpItemTreePrivate *private;
+  GimpContainer       *container;
+
+  g_return_val_if_fail (GIMP_IS_ITEM_TREE (tree), FALSE);
+  g_return_val_if_fail (parent != NULL, FALSE);
+
+  private = GIMP_ITEM_TREE_GET_PRIVATE (tree);
+
+  g_return_val_if_fail (G_TYPE_CHECK_INSTANCE_TYPE (item, private->item_type),
+                        FALSE);
+  g_return_val_if_fail (! gimp_item_is_attached (item), FALSE);
+  g_return_val_if_fail (gimp_item_get_image (item) == private->image, FALSE);
+  g_return_val_if_fail (*parent == NULL ||
+                        *parent == GIMP_IMAGE_ACTIVE_PARENT ||
+                        G_TYPE_CHECK_INSTANCE_TYPE (*parent, private->item_type),
+                        FALSE);
+  g_return_val_if_fail (*parent == NULL ||
+                        *parent == GIMP_IMAGE_ACTIVE_PARENT ||
+                        gimp_item_get_tree (*parent) == tree, FALSE);
+  g_return_val_if_fail (*parent == NULL ||
+                        *parent == GIMP_IMAGE_ACTIVE_PARENT ||
+                        gimp_viewable_get_children (GIMP_VIEWABLE (*parent)),
+                        FALSE);
+  g_return_val_if_fail (position != NULL, FALSE);
+
+  /*  if we want to insert in the active item's parent container  */
+  if (*parent == GIMP_IMAGE_ACTIVE_PARENT)
+    {
+      if (private->active_item)
+        {
+          /*  if the active item is a branch, add to the top of that
+           *  branch; add to the active item's parent container
+           *  otherwise
+           */
+          if (gimp_viewable_get_children (GIMP_VIEWABLE (private->active_item)))
+            {
+              *parent   = private->active_item;
+              *position = 0;
+            }
+          else
+            {
+              *parent = gimp_item_get_parent (private->active_item);
+            }
+        }
+      else
+        {
+          /*  use the toplevel container if there is no active item  */
+          *parent = NULL;
+        }
+    }
+
+  if (*parent)
+    container = gimp_viewable_get_children (GIMP_VIEWABLE (*parent));
+  else
+    container = tree->container;
+
+  /*  if we want to add on top of the active item  */
+  if (*position == -1)
+    {
+      if (private->active_item)
+        *position =
+          gimp_container_get_child_index (container,
+                                          GIMP_OBJECT (private->active_item));
+
+      /*  if the active item is not in the specified parent container,
+       *  fall back to index 0
+       */
+      if (*position == -1)
+        *position = 0;
+    }
+
+  /*  don't add at a non-existing index  */
+  *position = CLAMP (*position, 0, gimp_container_get_n_children (container));
+
+  return TRUE;
+}
+
+void
+gimp_item_tree_add_item (GimpItemTree *tree,
+                         GimpItem     *item,
+                         GimpItem     *parent,
+                         gint          position)
+{
+  GimpItemTreePrivate *private;
+  GimpContainer       *container;
+  GimpContainer       *children;
+
+  g_return_if_fail (GIMP_IS_ITEM_TREE (tree));
+
+  private = GIMP_ITEM_TREE_GET_PRIVATE (tree);
+
+  g_return_if_fail (G_TYPE_CHECK_INSTANCE_TYPE (item, private->item_type));
+  g_return_if_fail (! gimp_item_is_attached (item));
+  g_return_if_fail (gimp_item_get_image (item) == private->image);
+  g_return_if_fail (parent == NULL ||
+                    G_TYPE_CHECK_INSTANCE_TYPE (parent, private->item_type));
+  g_return_if_fail (parent == NULL || gimp_item_get_tree (parent) == tree);
+  g_return_if_fail (parent == NULL ||
+                    gimp_viewable_get_children (GIMP_VIEWABLE (parent)));
+
+  gimp_item_tree_uniquefy_name (tree, item, NULL);
+
+  children = gimp_viewable_get_children (GIMP_VIEWABLE (item));
+
+  if (children)
+    {
+      GList *list = gimp_item_stack_get_item_list (GIMP_ITEM_STACK (children));
+
+      while (list)
+        {
+          gimp_item_tree_uniquefy_name (tree, list->data, NULL);
+
+          list = g_list_remove (list, list->data);
+        }
+    }
+
+  if (parent)
+    container = gimp_viewable_get_children (GIMP_VIEWABLE (parent));
+  else
+    container = tree->container;
+
+  if (parent)
+    gimp_viewable_set_parent (GIMP_VIEWABLE (item),
+                              GIMP_VIEWABLE (parent));
+
+  gimp_container_insert (container, GIMP_OBJECT (item), position);
+
+  /*  if the item came from the undo stack, reset its "removed" state  */
+  if (gimp_item_is_removed (item))
+    gimp_item_unset_removed (item);
+}
+
+GimpItem *
+gimp_item_tree_remove_item (GimpItemTree *tree,
+                            GimpItem     *item,
+                            GimpItem     *new_active)
+{
+  GimpItemTreePrivate *private;
+  GimpItem            *parent;
+  GimpContainer       *container;
+  GimpContainer       *children;
+  gint                 index;
+
+  g_return_val_if_fail (GIMP_IS_ITEM_TREE (tree), NULL);
+
+  private = GIMP_ITEM_TREE_GET_PRIVATE (tree);
+
+  g_return_val_if_fail (G_TYPE_CHECK_INSTANCE_TYPE (item, private->item_type),
+                        NULL);
+  g_return_val_if_fail (gimp_item_get_tree (item) == tree, NULL);
+
+  parent    = gimp_item_get_parent (item);
+  container = gimp_item_get_container (item);
+  index     = gimp_item_get_index (item);
+
+  g_object_ref (item);
+
+  g_hash_table_remove (private->name_hash,
+                       gimp_object_get_name (item));
+
+  children = gimp_viewable_get_children (GIMP_VIEWABLE (item));
+
+  if (children)
+    {
+      GList *list = gimp_item_stack_get_item_list (GIMP_ITEM_STACK (children));
+
+      while (list)
+        {
+          g_hash_table_remove (private->name_hash,
+                               gimp_object_get_name (list->data));
+
+          list = g_list_remove (list, list->data);
+        }
+    }
+
+  gimp_container_remove (container, GIMP_OBJECT (item));
+
+  if (parent)
+    gimp_viewable_set_parent (GIMP_VIEWABLE (item), NULL);
+
+  gimp_item_removed (item);
+
+  if (! new_active)
+    {
+      gint n_children = gimp_container_get_n_children (container);
+
+      if (n_children > 0)
+        {
+          index = CLAMP (index, 0, n_children - 1);
+
+          new_active =
+            GIMP_ITEM (gimp_container_get_child_by_index (container, index));
+        }
+      else if (parent)
+        {
+          new_active = parent;
+        }
+    }
+
+  g_object_unref (item);
+
+  return new_active;
+}
+
+gboolean
+gimp_item_tree_reorder_item (GimpItemTree *tree,
+                             GimpItem     *item,
+                             GimpItem     *new_parent,
+                             gint          new_index,
+                             gboolean      push_undo,
+                             const gchar  *undo_desc)
+{
+  GimpItemTreePrivate *private;
+  GimpContainer       *container;
+  GimpContainer       *new_container;
+  gint                 n_items;
+
+  g_return_val_if_fail (GIMP_IS_ITEM_TREE (tree), FALSE);
+
+  private = GIMP_ITEM_TREE_GET_PRIVATE (tree);
+
+  g_return_val_if_fail (G_TYPE_CHECK_INSTANCE_TYPE (item, private->item_type),
+                        FALSE);
+  g_return_val_if_fail (gimp_item_get_tree (item) == tree, FALSE);
+  g_return_val_if_fail (new_parent == NULL ||
+                        G_TYPE_CHECK_INSTANCE_TYPE (new_parent,
+                                                    private->item_type),
+                        FALSE);
+  g_return_val_if_fail (new_parent == NULL ||
+                        gimp_item_get_tree (new_parent) == tree, FALSE);
+  g_return_val_if_fail (new_parent == NULL ||
+                        gimp_viewable_get_children (GIMP_VIEWABLE (new_parent)),
+                        FALSE);
+  g_return_val_if_fail (item != new_parent, FALSE);
+  g_return_val_if_fail (new_parent == NULL ||
+                        ! gimp_viewable_is_ancestor (GIMP_VIEWABLE (item),
+                                                     GIMP_VIEWABLE (new_parent)),
+                        FALSE);
+
+  container = gimp_item_get_container (item);
+
+  if (new_parent)
+    new_container = gimp_viewable_get_children (GIMP_VIEWABLE (new_parent));
+  else
+    new_container = tree->container;
+
+  n_items = gimp_container_get_n_children (new_container);
+
+  if (new_container == container)
+    n_items--;
+
+  new_index = CLAMP (new_index, 0, n_items);
+
+  if (new_container != container ||
+      new_index     != gimp_item_get_index (item))
+    {
+      if (push_undo)
+        gimp_image_undo_push_item_reorder (private->image, undo_desc, item);
+
+      if (new_container != container)
+        {
+          g_object_ref (item);
+
+          gimp_container_remove (container, GIMP_OBJECT (item));
+
+          gimp_viewable_set_parent (GIMP_VIEWABLE (item),
+                                    GIMP_VIEWABLE (new_parent));
+
+          gimp_container_insert (new_container, GIMP_OBJECT (item), new_index);
+
+          g_object_unref (item);
+        }
+      else
+        {
+          gimp_container_reorder (container, GIMP_OBJECT (item), new_index);
+        }
+    }
+
+  return TRUE;
+}
+
+void
+gimp_item_tree_rename_item (GimpItemTree *tree,
+                            GimpItem     *item,
+                            const gchar  *new_name,
+                            gboolean      push_undo,
+                            const gchar  *undo_desc)
+{
+  GimpItemTreePrivate *private;
+
+  g_return_if_fail (GIMP_IS_ITEM_TREE (tree));
+
+  private = GIMP_ITEM_TREE_GET_PRIVATE (tree);
+
+  g_return_if_fail (G_TYPE_CHECK_INSTANCE_TYPE (item, private->item_type));
+  g_return_if_fail (gimp_item_get_tree (item) == tree);
+  g_return_if_fail (new_name != NULL);
+
+  if (strcmp (new_name, gimp_object_get_name (item)))
+    {
+      if (push_undo)
+        gimp_image_undo_push_item_rename (gimp_item_get_image (item),
+                                          undo_desc, item);
+
+      gimp_item_tree_uniquefy_name (tree, item, new_name);
+    }
+}
+
+
+/*  private functions  */
+
+static void
+gimp_item_tree_uniquefy_name (GimpItemTree *tree,
+                              GimpItem     *item,
+                              const gchar  *new_name)
+{
+  GimpItemTreePrivate *private = GIMP_ITEM_TREE_GET_PRIVATE (tree);
+
+  if (new_name)
+    {
+      g_hash_table_remove (private->name_hash,
+                           gimp_object_get_name (item));
+
+      gimp_object_set_name (GIMP_OBJECT (item), new_name);
+    }
+
+  /* Remove any trailing whitespace. */
+  if (gimp_object_get_name (item))
+    {
+      gchar *name = g_strchomp (g_strdup (gimp_object_get_name (item)));
+
+      gimp_object_take_name (GIMP_OBJECT (item), name);
+    }
+
+  if (g_hash_table_lookup (private->name_hash,
+                           gimp_object_get_name (item)))
+    {
+      gchar      *name        = g_strdup (gimp_object_get_name (item));
+      gchar      *new_name    = NULL;
+      gint        number      = 0;
+      gint        precision   = 1;
+      GRegex     *end_numbers = g_regex_new (" ?#([0-9]+)\\s*$", 0, 0, NULL);
+      GMatchInfo *match_info  = NULL;
+
+      if (g_regex_match (end_numbers, name, 0, &match_info))
+        {
+          gchar *match;
+          gint   start_pos;
+
+          match  = g_match_info_fetch (match_info, 1);
+          if (match && match[0] == '0')
+            {
+              precision = strlen (match);
+            }
+          number = atoi (match);
+          g_free (match);
+
+          g_match_info_fetch_pos (match_info, 0,
+                                  &start_pos, NULL);
+          name[start_pos] = '\0';
+        }
+      g_match_info_free (match_info);
+      g_regex_unref (end_numbers);
+
+      do
+        {
+          number++;
+
+          g_free (new_name);
+
+          new_name = g_strdup_printf ("%s #%.*d",
+                                      name,
+                                      precision,
+                                      number);
+        }
+      while (g_hash_table_lookup (private->name_hash, new_name));
+
+      g_free (name);
+
+      gimp_object_take_name (GIMP_OBJECT (item), new_name);
+    }
+
+  g_hash_table_insert (private->name_hash,
+                       (gpointer) gimp_object_get_name (item),
+                       item);
+}
diff --git a/app/core/gimpitemtree.h b/app/core/gimpitemtree.h
new file mode 100644
index 0000000..4d3c6ea
--- /dev/null
+++ b/app/core/gimpitemtree.h
@@ -0,0 +1,89 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1997 Spencer Kimball and Peter Mattis
+ *
+ * gimpitemtree.h
+ * Copyright (C) 2010 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_ITEM_TREE_H__
+#define __GIMP_ITEM_TREE_H__
+
+
+#include "gimpobject.h"
+
+
+#define GIMP_TYPE_ITEM_TREE            (gimp_item_tree_get_type ())
+#define GIMP_ITEM_TREE(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_ITEM_TREE, GimpItemTree))
+#define GIMP_ITEM_TREE_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_ITEM_TREE, GimpItemTreeClass))
+#define GIMP_IS_ITEM_TREE(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_ITEM_TREE))
+#define GIMP_IS_ITEM_TREE_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_ITEM_TREE))
+
+
+typedef struct _GimpItemTreeClass GimpItemTreeClass;
+
+struct _GimpItemTree
+{
+  GimpObject     parent_instance;
+
+  GimpContainer *container;
+};
+
+struct _GimpItemTreeClass
+{
+  GimpObjectClass  parent_class;
+};
+
+
+GType          gimp_item_tree_get_type         (void) G_GNUC_CONST;
+GimpItemTree * gimp_item_tree_new              (GimpImage     *image,
+                                                GType          container_type,
+                                                GType          item_type);
+
+GimpItem     * gimp_item_tree_get_active_item  (GimpItemTree  *tree);
+void           gimp_item_tree_set_active_item  (GimpItemTree  *tree,
+                                                GimpItem      *item);
+
+GimpItem     * gimp_item_tree_get_item_by_name (GimpItemTree  *tree,
+                                                const gchar   *name);
+
+gboolean       gimp_item_tree_get_insert_pos   (GimpItemTree  *tree,
+                                                GimpItem      *item,
+                                                GimpItem     **parent,
+                                                gint          *position);
+
+void           gimp_item_tree_add_item         (GimpItemTree  *tree,
+                                                GimpItem      *item,
+                                                GimpItem      *parent,
+                                                gint           position);
+GimpItem     * gimp_item_tree_remove_item      (GimpItemTree  *tree,
+                                                GimpItem      *item,
+                                                GimpItem      *new_active);
+
+gboolean       gimp_item_tree_reorder_item     (GimpItemTree  *tree,
+                                                GimpItem      *item,
+                                                GimpItem      *new_parent,
+                                                gint           new_index,
+                                                gboolean       push_undo,
+                                                const gchar   *undo_desc);
+
+void           gimp_item_tree_rename_item      (GimpItemTree  *tree,
+                                                GimpItem      *item,
+                                                const gchar   *new_name,
+                                                gboolean       push_undo,
+                                                const gchar   *undo_desc);
+
+
+#endif  /*  __GIMP_ITEM_TREE_H__  */
diff --git a/app/core/gimpitemundo.c b/app/core/gimpitemundo.c
new file mode 100644
index 0000000..0a50d43
--- /dev/null
+++ b/app/core/gimpitemundo.c
@@ -0,0 +1,139 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gimpimage.h"
+#include "gimpitem.h"
+#include "gimpitemundo.h"
+
+
+enum
+{
+  PROP_0,
+  PROP_ITEM
+};
+
+
+static void   gimp_item_undo_constructed  (GObject      *object);
+static void   gimp_item_undo_set_property (GObject      *object,
+                                           guint         property_id,
+                                           const GValue *value,
+                                           GParamSpec   *pspec);
+static void   gimp_item_undo_get_property (GObject      *object,
+                                           guint         property_id,
+                                           GValue       *value,
+                                           GParamSpec   *pspec);
+
+static void   gimp_item_undo_free         (GimpUndo     *undo,
+                                           GimpUndoMode  undo_mode);
+
+
+G_DEFINE_TYPE (GimpItemUndo, gimp_item_undo, GIMP_TYPE_UNDO)
+
+#define parent_class gimp_item_undo_parent_class
+
+
+static void
+gimp_item_undo_class_init (GimpItemUndoClass *klass)
+{
+  GObjectClass  *object_class = G_OBJECT_CLASS (klass);
+  GimpUndoClass *undo_class   = GIMP_UNDO_CLASS (klass);
+
+  object_class->constructed  = gimp_item_undo_constructed;
+  object_class->set_property = gimp_item_undo_set_property;
+  object_class->get_property = gimp_item_undo_get_property;
+
+  undo_class->free           = gimp_item_undo_free;
+
+  g_object_class_install_property (object_class, PROP_ITEM,
+                                   g_param_spec_object ("item", NULL, NULL,
+                                                        GIMP_TYPE_ITEM,
+                                                        GIMP_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT_ONLY));
+}
+
+static void
+gimp_item_undo_init (GimpItemUndo *undo)
+{
+}
+
+static void
+gimp_item_undo_constructed (GObject *object)
+{
+  GimpItemUndo *item_undo = GIMP_ITEM_UNDO (object);
+
+  G_OBJECT_CLASS (parent_class)->constructed (object);
+
+  gimp_assert (GIMP_IS_ITEM (item_undo->item));
+}
+
+static void
+gimp_item_undo_set_property (GObject      *object,
+                             guint         property_id,
+                             const GValue *value,
+                             GParamSpec   *pspec)
+{
+  GimpItemUndo *item_undo = GIMP_ITEM_UNDO (object);
+
+  switch (property_id)
+    {
+    case PROP_ITEM:
+      item_undo->item = g_value_dup_object (value);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_item_undo_get_property (GObject    *object,
+                             guint       property_id,
+                             GValue     *value,
+                             GParamSpec *pspec)
+{
+  GimpItemUndo *item_undo = GIMP_ITEM_UNDO (object);
+
+  switch (property_id)
+    {
+    case PROP_ITEM:
+      g_value_set_object (value, item_undo->item);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_item_undo_free (GimpUndo     *undo,
+                     GimpUndoMode  undo_mode)
+{
+  GimpItemUndo *item_undo = GIMP_ITEM_UNDO (undo);
+
+  g_clear_object (&item_undo->item);
+
+  GIMP_UNDO_CLASS (parent_class)->free (undo, undo_mode);
+}
diff --git a/app/core/gimpitemundo.h b/app/core/gimpitemundo.h
new file mode 100644
index 0000000..91fe8d6
--- /dev/null
+++ b/app/core/gimpitemundo.h
@@ -0,0 +1,52 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_ITEM_UNDO_H__
+#define __GIMP_ITEM_UNDO_H__
+
+
+#include "gimpundo.h"
+
+
+#define GIMP_TYPE_ITEM_UNDO            (gimp_item_undo_get_type ())
+#define GIMP_ITEM_UNDO(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_ITEM_UNDO, GimpItemUndo))
+#define GIMP_ITEM_UNDO_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_ITEM_UNDO, GimpItemUndoClass))
+#define GIMP_IS_ITEM_UNDO(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_ITEM_UNDO))
+#define GIMP_IS_ITEM_UNDO_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_ITEM_UNDO))
+#define GIMP_ITEM_UNDO_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_ITEM_UNDO, GimpItemUndoClass))
+
+
+typedef struct _GimpItemUndo      GimpItemUndo;
+typedef struct _GimpItemUndoClass GimpItemUndoClass;
+
+struct _GimpItemUndo
+{
+  GimpUndo  parent_instance;
+
+  GimpItem *item;  /* the item this undo is for */
+};
+
+struct _GimpItemUndoClass
+{
+  GimpUndoClass  parent_class;
+};
+
+
+GType   gimp_item_undo_get_type (void) G_GNUC_CONST;
+
+
+#endif /* __GIMP_ITEM_UNDO_H__ */
diff --git a/app/core/gimplayer-floating-selection.c b/app/core/gimplayer-floating-selection.c
new file mode 100644
index 0000000..80222a2
--- /dev/null
+++ b/app/core/gimplayer-floating-selection.c
@@ -0,0 +1,332 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+
+#include "core-types.h"
+
+#include "gimpboundary.h"
+#include "gimpdrawable-filters.h"
+#include "gimpdrawable-floating-selection.h"
+#include "gimperror.h"
+#include "gimpimage.h"
+#include "gimpimage-undo.h"
+#include "gimpimage-undo-push.h"
+#include "gimplayer.h"
+#include "gimplayer-floating-selection.h"
+#include "gimplayermask.h"
+
+#include "gimp-intl.h"
+
+
+/* public functions  */
+
+void
+floating_sel_attach (GimpLayer    *layer,
+                     GimpDrawable *drawable)
+{
+  GimpImage *image;
+  GimpLayer *floating_sel;
+  GimpLayer *parent   = NULL;
+  gint       position = 0;
+
+  g_return_if_fail (GIMP_IS_LAYER (layer));
+  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
+  g_return_if_fail (gimp_item_is_attached (GIMP_ITEM (drawable)));
+  g_return_if_fail (drawable != GIMP_DRAWABLE (layer));
+  g_return_if_fail (gimp_item_get_image (GIMP_ITEM (layer)) ==
+                    gimp_item_get_image (GIMP_ITEM (drawable)));
+
+  image = gimp_item_get_image (GIMP_ITEM (drawable));
+
+  floating_sel = gimp_image_get_floating_selection (image);
+
+  /*  If there is already a floating selection, anchor it  */
+  if (floating_sel)
+    {
+      floating_sel_anchor (floating_sel);
+
+      /*  if we were pasting to the old floating selection, paste now
+       *  to the drawable
+       */
+      if (drawable == (GimpDrawable *) floating_sel)
+        drawable = gimp_image_get_active_drawable (image);
+    }
+
+  gimp_layer_set_lock_alpha (layer, TRUE, FALSE);
+
+  gimp_layer_set_floating_sel_drawable (layer, drawable);
+
+  /*  Floating selection layer placement, default to the top of the
+   *  layers stack; parent and position are adapted according to the
+   *  drawable associated with the floating selection.
+   */
+
+  if (GIMP_IS_LAYER_MASK (drawable))
+    {
+       GimpLayer *tmp = gimp_layer_mask_get_layer (GIMP_LAYER_MASK (drawable));
+
+       parent   = GIMP_LAYER (gimp_item_get_parent (GIMP_ITEM (tmp)));
+       position = gimp_item_get_index (GIMP_ITEM (tmp));
+    }
+  else if (GIMP_IS_LAYER (drawable))
+    {
+      parent   = GIMP_LAYER (gimp_item_get_parent (GIMP_ITEM (drawable)));
+      position = gimp_item_get_index (GIMP_ITEM (drawable));
+    }
+
+  gimp_image_add_layer (image, layer, parent, position, TRUE);
+}
+
+void
+floating_sel_anchor (GimpLayer *layer)
+{
+  GimpImage     *image;
+  GimpDrawable  *drawable;
+  GimpFilter    *filter = NULL;
+  GeglRectangle  bounding_box;
+  GeglRectangle  dr_bounding_box;
+  gint           off_x, off_y;
+  gint           dr_off_x, dr_off_y;
+
+  g_return_if_fail (GIMP_IS_LAYER (layer));
+  g_return_if_fail (gimp_layer_is_floating_sel (layer));
+
+  /* Don't let gimp_image_remove_layer free the layer while we still need it */
+  g_object_ref (layer);
+
+  image = gimp_item_get_image (GIMP_ITEM (layer));
+
+  gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_FS_ANCHOR,
+                               C_("undo-type", "Anchor Floating Selection"));
+
+  drawable = gimp_layer_get_floating_sel_drawable (layer);
+
+  gimp_item_get_offset (GIMP_ITEM (layer), &off_x, &off_y);
+  gimp_item_get_offset (GIMP_ITEM (drawable), &dr_off_x, &dr_off_y);
+
+  bounding_box    = gimp_drawable_get_bounding_box (GIMP_DRAWABLE (layer));
+  dr_bounding_box = gimp_drawable_get_bounding_box (drawable);
+
+  bounding_box.x    += off_x;
+  bounding_box.y    += off_y;
+
+  dr_bounding_box.x += dr_off_x;
+  dr_bounding_box.y += dr_off_y;
+
+  if (gimp_item_get_visible (GIMP_ITEM (layer)) &&
+      gegl_rectangle_intersect (NULL, &bounding_box, &dr_bounding_box))
+    {
+      filter = gimp_drawable_get_floating_sel_filter (drawable);
+    }
+
+  if (filter)
+    {
+      gimp_drawable_merge_filter (drawable, filter, NULL, NULL,
+                                  NULL, FALSE, FALSE, FALSE);
+    }
+
+  gimp_image_remove_layer (image, layer, TRUE, NULL);
+
+  gimp_image_undo_group_end (image);
+
+  /*  invalidate the boundaries  */
+  gimp_drawable_invalidate_boundary (GIMP_DRAWABLE (gimp_image_get_mask (image)));
+
+  g_object_unref (layer);
+}
+
+gboolean
+floating_sel_to_layer (GimpLayer  *layer,
+                       GError    **error)
+{
+  GimpItem  *item;
+  GimpImage *image;
+
+  g_return_val_if_fail (GIMP_IS_LAYER (layer), FALSE);
+  g_return_val_if_fail (gimp_layer_is_floating_sel (layer), FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  item  = GIMP_ITEM (layer);
+  image = gimp_item_get_image (item);
+
+  /*  Check if the floating layer belongs to a channel  */
+  if (GIMP_IS_CHANNEL (gimp_layer_get_floating_sel_drawable (layer)))
+    {
+      g_set_error_literal (error, GIMP_ERROR, GIMP_FAILED,
+                           _("Cannot create a new layer from the floating "
+                             "selection because it belongs to a layer mask "
+                             "or channel."));
+      return FALSE;
+    }
+
+  gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_FS_TO_LAYER,
+                               C_("undo-type", "Floating Selection to Layer"));
+
+  gimp_image_undo_push_fs_to_layer (image, NULL, layer);
+
+  gimp_drawable_detach_floating_sel (gimp_layer_get_floating_sel_drawable (layer));
+  gimp_layer_set_floating_sel_drawable (layer, NULL);
+
+  gimp_item_set_visible (item, TRUE, TRUE);
+  gimp_layer_set_lock_alpha (layer, FALSE, TRUE);
+
+  gimp_image_undo_group_end (image);
+
+  /* When the floating selection is converted to/from a normal layer
+   * it does something resembling a name change, so emit the
+   * "name-changed" signal
+   */
+  gimp_object_name_changed (GIMP_OBJECT (layer));
+
+  gimp_drawable_update (GIMP_DRAWABLE (layer),
+                        0, 0,
+                        gimp_item_get_width  (item),
+                        gimp_item_get_height (item));
+
+  return TRUE;
+}
+
+void
+floating_sel_activate_drawable (GimpLayer *layer)
+{
+  GimpImage    *image;
+  GimpDrawable *drawable;
+
+  g_return_if_fail (GIMP_IS_LAYER (layer));
+  g_return_if_fail (gimp_layer_is_floating_sel (layer));
+
+  image = gimp_item_get_image (GIMP_ITEM (layer));
+
+  drawable = gimp_layer_get_floating_sel_drawable (layer);
+
+  /*  set the underlying drawable to active  */
+  if (GIMP_IS_LAYER_MASK (drawable))
+    {
+      GimpLayerMask *mask = GIMP_LAYER_MASK (drawable);
+
+      gimp_image_set_active_layer (image, gimp_layer_mask_get_layer (mask));
+    }
+  else if (GIMP_IS_CHANNEL (drawable))
+    {
+      gimp_image_set_active_channel (image, GIMP_CHANNEL (drawable));
+    }
+  else
+    {
+      gimp_image_set_active_layer (image, GIMP_LAYER (drawable));
+    }
+}
+
+const GimpBoundSeg *
+floating_sel_boundary (GimpLayer *layer,
+                       gint      *n_segs)
+{
+  g_return_val_if_fail (GIMP_IS_LAYER (layer), NULL);
+  g_return_val_if_fail (gimp_layer_is_floating_sel (layer), NULL);
+  g_return_val_if_fail (n_segs != NULL, NULL);
+
+  if (layer->fs.boundary_known == FALSE)
+    {
+      gint width, height;
+      gint off_x, off_y;
+
+      width  = gimp_item_get_width  (GIMP_ITEM (layer));
+      height = gimp_item_get_height (GIMP_ITEM (layer));
+      gimp_item_get_offset (GIMP_ITEM (layer), &off_x, &off_y);
+
+      if (layer->fs.segs)
+        g_free (layer->fs.segs);
+
+      if (gimp_drawable_has_alpha (GIMP_DRAWABLE (layer)))
+        {
+          GeglBuffer *buffer;
+          gint        i;
+
+          /*  find the segments  */
+          buffer = gimp_drawable_get_buffer (GIMP_DRAWABLE (layer));
+
+          layer->fs.segs = gimp_boundary_find (buffer, NULL,
+                                               babl_format ("A float"),
+                                               GIMP_BOUNDARY_WITHIN_BOUNDS,
+                                               0, 0, width, height,
+                                               GIMP_BOUNDARY_HALF_WAY,
+                                               &layer->fs.num_segs);
+
+          /*  offset the segments  */
+          for (i = 0; i < layer->fs.num_segs; i++)
+            {
+              layer->fs.segs[i].x1 += off_x;
+              layer->fs.segs[i].y1 += off_y;
+              layer->fs.segs[i].x2 += off_x;
+              layer->fs.segs[i].y2 += off_y;
+            }
+        }
+      else
+        {
+          layer->fs.num_segs = 4;
+          layer->fs.segs     = g_new0 (GimpBoundSeg, 4);
+
+          /* top */
+          layer->fs.segs[0].x1 = off_x;
+          layer->fs.segs[0].y1 = off_y;
+          layer->fs.segs[0].x2 = off_x + width;
+          layer->fs.segs[0].y2 = off_y;
+
+          /* left */
+          layer->fs.segs[1].x1 = off_x;
+          layer->fs.segs[1].y1 = off_y;
+          layer->fs.segs[1].x2 = off_x;
+          layer->fs.segs[1].y2 = off_y + height;
+
+          /* right */
+          layer->fs.segs[2].x1 = off_x + width;
+          layer->fs.segs[2].y1 = off_y;
+          layer->fs.segs[2].x2 = off_x + width;
+          layer->fs.segs[2].y2 = off_y + height;
+
+          /* bottom */
+          layer->fs.segs[3].x1 = off_x;
+          layer->fs.segs[3].y1 = off_y + height;
+          layer->fs.segs[3].x2 = off_x + width;
+          layer->fs.segs[3].y2 = off_y + height;
+        }
+
+      layer->fs.boundary_known = TRUE;
+    }
+
+  *n_segs = layer->fs.num_segs;
+
+  return layer->fs.segs;
+}
+
+void
+floating_sel_invalidate (GimpLayer *layer)
+{
+  g_return_if_fail (GIMP_IS_LAYER (layer));
+  g_return_if_fail (gimp_layer_is_floating_sel (layer));
+
+  /*  Invalidate the attached-to drawable's preview  */
+  gimp_viewable_invalidate_preview (GIMP_VIEWABLE (gimp_layer_get_floating_sel_drawable (layer)));
+
+  /*  Invalidate the boundary  */
+  layer->fs.boundary_known = FALSE;
+}
diff --git a/app/core/gimplayer-floating-selection.h b/app/core/gimplayer-floating-selection.h
new file mode 100644
index 0000000..e111c1a
--- /dev/null
+++ b/app/core/gimplayer-floating-selection.h
@@ -0,0 +1,33 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_LAYER_FLOATING_SELECTION_H__
+#define __GIMP_LAYER_FLOATING_SELECTION_H__
+
+
+void                 floating_sel_attach            (GimpLayer     *layer,
+                                                     GimpDrawable  *drawable);
+void                 floating_sel_anchor            (GimpLayer     *layer);
+gboolean             floating_sel_to_layer          (GimpLayer     *layer,
+                                                     GError       **error);
+void                 floating_sel_activate_drawable (GimpLayer     *layer);
+const GimpBoundSeg * floating_sel_boundary          (GimpLayer     *layer,
+                                                     gint          *n_segs);
+void                 floating_sel_invalidate        (GimpLayer     *layer);
+
+
+#endif /* __GIMP_LAYER_FLOATING_SELECTION_H__ */
diff --git a/app/core/gimplayer-new.c b/app/core/gimplayer-new.c
new file mode 100644
index 0000000..7ea2450
--- /dev/null
+++ b/app/core/gimplayer-new.c
@@ -0,0 +1,253 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <cairo.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpcolor/gimpcolor.h"
+#include "libgimpconfig/gimpconfig.h"
+
+#include "core-types.h"
+
+#include "gegl/gimp-babl.h"
+#include "gegl/gimp-gegl-loops.h"
+
+#include "gimpbuffer.h"
+#include "gimpimage.h"
+#include "gimpimage-color-profile.h"
+#include "gimplayer.h"
+#include "gimplayer-new.h"
+
+
+/*  local function prototypes  */
+
+static void   gimp_layer_new_convert_buffer (GimpLayer         *layer,
+                                             GeglBuffer        *src_buffer,
+                                             GimpColorProfile  *src_profile,
+                                             GError           **error);
+
+
+/*  public functions  */
+
+GimpLayer *
+gimp_layer_new (GimpImage     *image,
+                gint           width,
+                gint           height,
+                const Babl    *format,
+                const gchar   *name,
+                gdouble        opacity,
+                GimpLayerMode  mode)
+{
+  GimpLayer *layer;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (width > 0, NULL);
+  g_return_val_if_fail (height > 0, NULL);
+  g_return_val_if_fail (format != NULL, NULL);
+
+  layer = GIMP_LAYER (gimp_drawable_new (GIMP_TYPE_LAYER,
+                                         image, name,
+                                         0, 0, width, height,
+                                         format));
+
+  gimp_layer_set_opacity (layer, opacity, FALSE);
+  gimp_layer_set_mode (layer, mode, FALSE);
+
+  return layer;
+}
+
+/**
+ * gimp_layer_new_from_buffer:
+ * @buffer:     The buffer to make the new layer from.
+ * @dest_image: The image the new layer will be added to.
+ * @format:     The #Babl format of the new layer.
+ * @name:       The new layer's name.
+ * @opacity:    The new layer's opacity.
+ * @mode:       The new layer's mode.
+ *
+ * Copies %buffer to a layer taking into consideration the
+ * possibility of transforming the contents to meet the requirements
+ * of the target image type
+ *
+ * Return value: The new layer.
+ **/
+GimpLayer *
+gimp_layer_new_from_buffer (GimpBuffer    *buffer,
+                            GimpImage     *dest_image,
+                            const Babl    *format,
+                            const gchar   *name,
+                            gdouble        opacity,
+                            GimpLayerMode  mode)
+{
+  g_return_val_if_fail (GIMP_IS_BUFFER (buffer), NULL);
+  g_return_val_if_fail (GIMP_IS_IMAGE (dest_image), NULL);
+  g_return_val_if_fail (format != NULL, NULL);
+
+  return gimp_layer_new_from_gegl_buffer (gimp_buffer_get_buffer (buffer),
+                                          dest_image, format,
+                                          name, opacity, mode,
+                                          gimp_buffer_get_color_profile (buffer));
+}
+
+/**
+ * gimp_layer_new_from_gegl_buffer:
+ * @buffer:     The buffer to make the new layer from.
+ * @dest_image: The image the new layer will be added to.
+ * @format:     The #Babl format of the new layer.
+ * @name:       The new layer's name.
+ * @opacity:    The new layer's opacity.
+ * @mode:       The new layer's mode.
+ *
+ * Copies %buffer to a layer taking into consideration the
+ * possibility of transforming the contents to meet the requirements
+ * of the target image type
+ *
+ * Return value: The new layer.
+ **/
+GimpLayer *
+gimp_layer_new_from_gegl_buffer (GeglBuffer       *buffer,
+                                 GimpImage        *dest_image,
+                                 const Babl       *format,
+                                 const gchar      *name,
+                                 gdouble           opacity,
+                                 GimpLayerMode     mode,
+                                 GimpColorProfile *buffer_profile)
+{
+  GimpLayer           *layer;
+  const GeglRectangle *extent;
+
+  g_return_val_if_fail (GEGL_IS_BUFFER (buffer), NULL);
+  g_return_val_if_fail (GIMP_IS_IMAGE (dest_image), NULL);
+  g_return_val_if_fail (format != NULL, NULL);
+  g_return_val_if_fail (buffer_profile == NULL ||
+                        GIMP_IS_COLOR_PROFILE (buffer_profile), NULL);
+
+  extent = gegl_buffer_get_extent (buffer);
+
+  /*  do *not* use the buffer's format because this function gets
+   *  buffers of any format passed, and converts them
+   */
+  layer = gimp_layer_new (dest_image,
+                          extent->width, extent->height,
+                          format,
+                          name, opacity, mode);
+
+  if (extent->x != 0 || extent->y != 0)
+    gimp_item_translate (GIMP_ITEM (layer), extent->x, extent->y, FALSE);
+
+  gimp_layer_new_convert_buffer (layer, buffer, buffer_profile, NULL);
+
+  return layer;
+}
+
+/**
+ * gimp_layer_new_from_pixbuf:
+ * @pixbuf:     The pixbuf to make the new layer from.
+ * @dest_image: The image the new layer will be added to.
+ * @format:     The #Babl format of the new layer.
+ * @name:       The new layer's name.
+ * @opacity:    The new layer's opacity.
+ * @mode:       The new layer's mode.
+ *
+ * Copies %pixbuf to a layer taking into consideration the
+ * possibility of transforming the contents to meet the requirements
+ * of the target image type
+ *
+ * Return value: The new layer.
+ **/
+GimpLayer *
+gimp_layer_new_from_pixbuf (GdkPixbuf     *pixbuf,
+                            GimpImage     *dest_image,
+                            const Babl    *format,
+                            const gchar   *name,
+                            gdouble        opacity,
+                            GimpLayerMode  mode)
+{
+  GimpLayer        *layer;
+  GeglBuffer       *buffer;
+  guint8           *icc_data;
+  gsize             icc_len;
+  GimpColorProfile *profile = NULL;
+
+  g_return_val_if_fail (GDK_IS_PIXBUF (pixbuf), NULL);
+  g_return_val_if_fail (GIMP_IS_IMAGE (dest_image), NULL);
+  g_return_val_if_fail (format != NULL, NULL);
+
+  layer = gimp_layer_new (dest_image,
+                          gdk_pixbuf_get_width  (pixbuf),
+                          gdk_pixbuf_get_height (pixbuf),
+                          format, name, opacity, mode);
+
+  buffer = gimp_pixbuf_create_buffer (pixbuf);
+
+  icc_data = gimp_pixbuf_get_icc_profile (pixbuf, &icc_len);
+  if (icc_data)
+    {
+      profile = gimp_color_profile_new_from_icc_profile (icc_data, icc_len,
+                                                         NULL);
+      g_free (icc_data);
+    }
+
+  gimp_layer_new_convert_buffer (layer, buffer, profile, NULL);
+
+  if (profile)
+    g_object_unref (profile);
+
+  g_object_unref (buffer);
+
+  return layer;
+}
+
+
+/*  private functions  */
+
+static void
+gimp_layer_new_convert_buffer (GimpLayer         *layer,
+                               GeglBuffer        *src_buffer,
+                               GimpColorProfile  *src_profile,
+                               GError           **error)
+{
+  GimpDrawable     *drawable    = GIMP_DRAWABLE (layer);
+  GimpImage        *image       = gimp_item_get_image (GIMP_ITEM (layer));
+  GeglBuffer       *dest_buffer = gimp_drawable_get_buffer (drawable);
+  GimpColorProfile *dest_profile;
+
+  if (! gimp_image_get_is_color_managed (image))
+    {
+      gimp_gegl_buffer_copy (src_buffer, NULL, GEGL_ABYSS_NONE,
+                             dest_buffer, NULL);
+      return;
+    }
+
+  if (! src_profile)
+    {
+      const Babl *src_format = gegl_buffer_get_format (src_buffer);
+
+      src_profile = gimp_babl_format_get_color_profile (src_format);
+    }
+
+  dest_profile =
+    gimp_color_managed_get_color_profile (GIMP_COLOR_MANAGED (layer));
+
+  gimp_gegl_convert_color_profile (src_buffer,  NULL, src_profile,
+                                   dest_buffer, NULL, dest_profile,
+                                   GIMP_COLOR_RENDERING_INTENT_PERCEPTUAL,
+                                   TRUE, NULL);
+}
diff --git a/app/core/gimplayer-new.h b/app/core/gimplayer-new.h
new file mode 100644
index 0000000..58b3aa9
--- /dev/null
+++ b/app/core/gimplayer-new.h
@@ -0,0 +1,51 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_LAYER_NEW_H__
+#define __GIMP_LAYER_NEW_H__
+
+
+GimpLayer * gimp_layer_new                  (GimpImage        *image,
+                                             gint              width,
+                                             gint              height,
+                                             const Babl       *format,
+                                             const gchar      *name,
+                                             gdouble           opacity,
+                                             GimpLayerMode     mode);
+
+GimpLayer * gimp_layer_new_from_buffer      (GimpBuffer       *buffer,
+                                             GimpImage        *dest_image,
+                                             const Babl       *format,
+                                             const gchar      *name,
+                                             gdouble           opacity,
+                                             GimpLayerMode     mode);
+GimpLayer * gimp_layer_new_from_gegl_buffer (GeglBuffer       *buffer,
+                                             GimpImage        *dest_image,
+                                             const Babl       *format,
+                                             const gchar      *name,
+                                             gdouble           opacity,
+                                             GimpLayerMode     mode,
+                                             GimpColorProfile *buffer_profile);
+GimpLayer * gimp_layer_new_from_pixbuf      (GdkPixbuf        *pixbuf,
+                                             GimpImage        *dest_image,
+                                             const Babl       *format,
+                                             const gchar      *name,
+                                             gdouble           opacity,
+                                             GimpLayerMode     mode);
+
+
+#endif /* __GIMP_LAYER_NEW_H__ */
diff --git a/app/core/gimplayer.c b/app/core/gimplayer.c
new file mode 100644
index 0000000..3887007
--- /dev/null
+++ b/app/core/gimplayer.c
@@ -0,0 +1,2943 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+#include <cairo.h>
+#include <gegl.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpcolor/gimpcolor.h"
+#include "libgimpconfig/gimpconfig.h"
+#include "libgimpmath/gimpmath.h"
+
+#include "core-types.h"
+
+#include "operations/layer-modes/gimp-layer-modes.h"
+
+#include "gegl/gimp-babl.h"
+#include "gegl/gimp-gegl-apply-operation.h"
+#include "gegl/gimp-gegl-loops.h"
+#include "gegl/gimp-gegl-nodes.h"
+
+#include "gimpboundary.h"
+#include "gimpchannel-select.h"
+#include "gimpcontext.h"
+#include "gimpcontainer.h"
+#include "gimpdrawable-floating-selection.h"
+#include "gimperror.h"
+#include "gimpgrouplayer.h"
+#include "gimpimage-undo-push.h"
+#include "gimpimage-undo.h"
+#include "gimpimage.h"
+#include "gimpimage-color-profile.h"
+#include "gimplayer-floating-selection.h"
+#include "gimplayer.h"
+#include "gimplayermask.h"
+#include "gimpmarshal.h"
+#include "gimpobjectqueue.h"
+#include "gimppickable.h"
+#include "gimpprogress.h"
+
+#include "gimp-intl.h"
+
+
+enum
+{
+  OPACITY_CHANGED,
+  MODE_CHANGED,
+  BLEND_SPACE_CHANGED,
+  COMPOSITE_SPACE_CHANGED,
+  COMPOSITE_MODE_CHANGED,
+  EFFECTIVE_MODE_CHANGED,
+  EXCLUDES_BACKDROP_CHANGED,
+  LOCK_ALPHA_CHANGED,
+  MASK_CHANGED,
+  APPLY_MASK_CHANGED,
+  EDIT_MASK_CHANGED,
+  SHOW_MASK_CHANGED,
+  LAST_SIGNAL
+};
+
+enum
+{
+  PROP_0,
+  PROP_OPACITY,
+  PROP_MODE,
+  PROP_BLEND_SPACE,
+  PROP_COMPOSITE_SPACE,
+  PROP_COMPOSITE_MODE,
+  PROP_EXCLUDES_BACKDROP,
+  PROP_LOCK_ALPHA,
+  PROP_MASK,
+  PROP_FLOATING_SELECTION
+};
+
+
+static void       gimp_color_managed_iface_init (GimpColorManagedInterface *iface);
+static void       gimp_pickable_iface_init      (GimpPickableInterface     *iface);
+
+static void       gimp_layer_set_property       (GObject            *object,
+                                                 guint               property_id,
+                                                 const GValue       *value,
+                                                 GParamSpec         *pspec);
+static void       gimp_layer_get_property       (GObject            *object,
+                                                 guint               property_id,
+                                                 GValue             *value,
+                                                 GParamSpec         *pspec);
+static void       gimp_layer_dispose            (GObject            *object);
+static void       gimp_layer_finalize           (GObject            *object);
+static void       gimp_layer_notify             (GObject            *object,
+                                                 GParamSpec         *pspec);
+
+static void       gimp_layer_name_changed       (GimpObject         *object);
+static gint64     gimp_layer_get_memsize        (GimpObject         *object,
+                                                 gint64             *gui_size);
+
+static void       gimp_layer_invalidate_preview (GimpViewable       *viewable);
+static gchar    * gimp_layer_get_description    (GimpViewable       *viewable,
+                                                 gchar             **tooltip);
+
+static GeglNode * gimp_layer_get_node           (GimpFilter         *filter);
+
+static void       gimp_layer_removed            (GimpItem           *item);
+static void       gimp_layer_unset_removed      (GimpItem           *item);
+static gboolean   gimp_layer_is_attached        (GimpItem           *item);
+static GimpItemTree * gimp_layer_get_tree       (GimpItem           *item);
+static GimpItem * gimp_layer_duplicate          (GimpItem           *item,
+                                                 GType               new_type);
+static void       gimp_layer_convert            (GimpItem           *item,
+                                                 GimpImage          *dest_image,
+                                                 GType               old_type);
+static gboolean   gimp_layer_rename             (GimpItem           *item,
+                                                 const gchar        *new_name,
+                                                 const gchar        *undo_desc,
+                                                 GError            **error);
+static void       gimp_layer_start_move         (GimpItem           *item,
+                                                 gboolean            push_undo);
+static void       gimp_layer_end_move           (GimpItem           *item,
+                                                 gboolean            push_undo);
+static void       gimp_layer_translate          (GimpItem           *item,
+                                                 gdouble             offset_x,
+                                                 gdouble             offset_y,
+                                                 gboolean            push_undo);
+static void       gimp_layer_scale              (GimpItem           *item,
+                                                 gint                new_width,
+                                                 gint                new_height,
+                                                 gint                new_offset_x,
+                                                 gint                new_offset_y,
+                                                 GimpInterpolationType  interp_type,
+                                                 GimpProgress       *progress);
+static void       gimp_layer_resize             (GimpItem           *item,
+                                                 GimpContext        *context,
+                                                 GimpFillType        fill_type,
+                                                 gint                new_width,
+                                                 gint                new_height,
+                                                 gint                offset_x,
+                                                 gint                offset_y);
+static void       gimp_layer_flip               (GimpItem           *item,
+                                                 GimpContext        *context,
+                                                 GimpOrientationType flip_type,
+                                                 gdouble             axis,
+                                                 gboolean            clip_result);
+static void       gimp_layer_rotate             (GimpItem           *item,
+                                                 GimpContext        *context,
+                                                 GimpRotationType    rotate_type,
+                                                 gdouble             center_x,
+                                                 gdouble             center_y,
+                                                 gboolean            clip_result);
+static void       gimp_layer_transform          (GimpItem           *item,
+                                                 GimpContext        *context,
+                                                 const GimpMatrix3  *matrix,
+                                                 GimpTransformDirection direction,
+                                                 GimpInterpolationType  interpolation_type,
+                                                 GimpTransformResize clip_result,
+                                                 GimpProgress       *progress);
+static void       gimp_layer_to_selection       (GimpItem           *item,
+                                                 GimpChannelOps      op,
+                                                 gboolean            antialias,
+                                                 gboolean            feather,
+                                                 gdouble             feather_radius_x,
+                                                 gdouble             feather_radius_y);
+
+static void       gimp_layer_alpha_changed      (GimpDrawable       *drawable);
+static gint64     gimp_layer_estimate_memsize   (GimpDrawable       *drawable,
+                                                 GimpComponentType   component_type,
+                                                 gint                width,
+                                                 gint                height);
+static gboolean   gimp_layer_supports_alpha     (GimpDrawable       *drawable);
+static void       gimp_layer_convert_type       (GimpDrawable       *drawable,
+                                                 GimpImage          *dest_image,
+                                                 const Babl         *new_format,
+                                                 GimpColorProfile   *dest_profile,
+                                                 GeglDitherMethod    layer_dither_type,
+                                                 GeglDitherMethod    mask_dither_type,
+                                                 gboolean            push_undo,
+                                                 GimpProgress       *progress);
+static void    gimp_layer_invalidate_boundary   (GimpDrawable       *drawable);
+static void    gimp_layer_get_active_components (GimpDrawable       *drawable,
+                                                 gboolean           *active);
+static GimpComponentMask
+               gimp_layer_get_active_mask       (GimpDrawable       *drawable);
+static void    gimp_layer_set_buffer            (GimpDrawable       *drawable,
+                                                 gboolean            push_undo,
+                                                 const gchar        *undo_desc,
+                                                 GeglBuffer         *buffer,
+                                                 const GeglRectangle *bounds);
+static GeglRectangle
+               gimp_layer_get_bounding_box      (GimpDrawable       *drawable);
+
+static GimpColorProfile *
+               gimp_layer_get_color_profile     (GimpColorManaged   *managed);
+
+static gdouble gimp_layer_get_opacity_at        (GimpPickable       *pickable,
+                                                 gint                x,
+                                                 gint                y);
+static void    gimp_layer_pixel_to_srgb         (GimpPickable       *pickable,
+                                                 const Babl         *format,
+                                                 gpointer            pixel,
+                                                 GimpRGB            *color);
+static void    gimp_layer_srgb_to_pixel         (GimpPickable       *pickable,
+                                                 const GimpRGB      *color,
+                                                 const Babl         *format,
+                                                 gpointer            pixel);
+
+static void       gimp_layer_real_translate     (GimpLayer          *layer,
+                                                 gint                offset_x,
+                                                 gint                offset_y);
+static void       gimp_layer_real_scale         (GimpLayer          *layer,
+                                                 gint                new_width,
+                                                 gint                new_height,
+                                                 gint                new_offset_x,
+                                                 gint                new_offset_y,
+                                                 GimpInterpolationType  interp_type,
+                                                 GimpProgress       *progress);
+static void       gimp_layer_real_resize        (GimpLayer          *layer,
+                                                 GimpContext        *context,
+                                                 GimpFillType        fill_type,
+                                                 gint                new_width,
+                                                 gint                new_height,
+                                                 gint                offset_x,
+                                                 gint                offset_y);
+static void       gimp_layer_real_flip          (GimpLayer          *layer,
+                                                 GimpContext        *context,
+                                                 GimpOrientationType flip_type,
+                                                 gdouble             axis,
+                                                 gboolean            clip_result);
+static void       gimp_layer_real_rotate        (GimpLayer          *layer,
+                                                 GimpContext        *context,
+                                                 GimpRotationType    rotate_type,
+                                                 gdouble             center_x,
+                                                 gdouble             center_y,
+                                                 gboolean            clip_result);
+static void       gimp_layer_real_transform     (GimpLayer          *layer,
+                                                 GimpContext        *context,
+                                                 const GimpMatrix3  *matrix,
+                                                 GimpTransformDirection direction,
+                                                 GimpInterpolationType  interpolation_type,
+                                                 GimpTransformResize clip_result,
+                                                 GimpProgress       *progress);
+static void       gimp_layer_real_convert_type  (GimpLayer          *layer,
+                                                 GimpImage          *dest_image,
+                                                 const Babl         *new_format,
+                                                 GimpColorProfile   *dest_profile,
+                                                 GeglDitherMethod    layer_dither_type,
+                                                 GeglDitherMethod    mask_dither_type,
+                                                 gboolean            push_undo,
+                                                 GimpProgress       *progress);
+static GeglRectangle
+               gimp_layer_real_get_bounding_box (GimpLayer          *layer);
+static void  gimp_layer_real_get_effective_mode (GimpLayer          *layer,
+                                                 GimpLayerMode          *mode,
+                                                 GimpLayerColorSpace    *blend_space,
+                                                 GimpLayerColorSpace    *composite_space,
+                                                 GimpLayerCompositeMode *composite_mode);
+static gboolean
+          gimp_layer_real_get_excludes_backdrop (GimpLayer          *layer);
+
+static void       gimp_layer_layer_mask_update  (GimpDrawable       *layer_mask,
+                                                 gint                x,
+                                                 gint                y,
+                                                 gint                width,
+                                                 gint                height,
+                                                 GimpLayer          *layer);
+
+
+G_DEFINE_TYPE_WITH_CODE (GimpLayer, gimp_layer, GIMP_TYPE_DRAWABLE,
+                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_COLOR_MANAGED,
+                                                gimp_color_managed_iface_init)
+                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_PICKABLE,
+                                                gimp_pickable_iface_init))
+
+#define parent_class gimp_layer_parent_class
+
+static guint layer_signals[LAST_SIGNAL] = { 0 };
+
+
+static void
+gimp_layer_class_init (GimpLayerClass *klass)
+{
+  GObjectClass      *object_class      = G_OBJECT_CLASS (klass);
+  GimpObjectClass   *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+  GimpViewableClass *viewable_class    = GIMP_VIEWABLE_CLASS (klass);
+  GimpFilterClass   *filter_class      = GIMP_FILTER_CLASS (klass);
+  GimpItemClass     *item_class        = GIMP_ITEM_CLASS (klass);
+  GimpDrawableClass *drawable_class    = GIMP_DRAWABLE_CLASS (klass);
+
+  layer_signals[OPACITY_CHANGED] =
+    g_signal_new ("opacity-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpLayerClass, opacity_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  layer_signals[MODE_CHANGED] =
+    g_signal_new ("mode-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpLayerClass, mode_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  layer_signals[BLEND_SPACE_CHANGED] =
+    g_signal_new ("blend-space-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpLayerClass, blend_space_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  layer_signals[COMPOSITE_SPACE_CHANGED] =
+    g_signal_new ("composite-space-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpLayerClass, composite_space_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  layer_signals[COMPOSITE_MODE_CHANGED] =
+    g_signal_new ("composite-mode-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpLayerClass, composite_mode_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  layer_signals[EFFECTIVE_MODE_CHANGED] =
+    g_signal_new ("effective-mode-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpLayerClass, effective_mode_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  layer_signals[EXCLUDES_BACKDROP_CHANGED] =
+    g_signal_new ("excludes-backdrop-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpLayerClass, excludes_backdrop_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  layer_signals[LOCK_ALPHA_CHANGED] =
+    g_signal_new ("lock-alpha-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpLayerClass, lock_alpha_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  layer_signals[MASK_CHANGED] =
+    g_signal_new ("mask-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpLayerClass, mask_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  layer_signals[APPLY_MASK_CHANGED] =
+    g_signal_new ("apply-mask-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpLayerClass, apply_mask_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  layer_signals[EDIT_MASK_CHANGED] =
+    g_signal_new ("edit-mask-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpLayerClass, edit_mask_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  layer_signals[SHOW_MASK_CHANGED] =
+    g_signal_new ("show-mask-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpLayerClass, show_mask_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  object_class->set_property          = gimp_layer_set_property;
+  object_class->get_property          = gimp_layer_get_property;
+  object_class->dispose               = gimp_layer_dispose;
+  object_class->finalize              = gimp_layer_finalize;
+  object_class->notify                = gimp_layer_notify;
+
+  gimp_object_class->name_changed     = gimp_layer_name_changed;
+  gimp_object_class->get_memsize      = gimp_layer_get_memsize;
+
+  viewable_class->default_icon_name   = "gimp-layer";
+  viewable_class->invalidate_preview  = gimp_layer_invalidate_preview;
+  viewable_class->get_description     = gimp_layer_get_description;
+
+  filter_class->get_node              = gimp_layer_get_node;
+
+  item_class->removed                 = gimp_layer_removed;
+  item_class->unset_removed           = gimp_layer_unset_removed;
+  item_class->is_attached             = gimp_layer_is_attached;
+  item_class->get_tree                = gimp_layer_get_tree;
+  item_class->duplicate               = gimp_layer_duplicate;
+  item_class->convert                 = gimp_layer_convert;
+  item_class->rename                  = gimp_layer_rename;
+  item_class->start_move              = gimp_layer_start_move;
+  item_class->end_move                = gimp_layer_end_move;
+  item_class->translate               = gimp_layer_translate;
+  item_class->scale                   = gimp_layer_scale;
+  item_class->resize                  = gimp_layer_resize;
+  item_class->flip                    = gimp_layer_flip;
+  item_class->rotate                  = gimp_layer_rotate;
+  item_class->transform               = gimp_layer_transform;
+  item_class->to_selection            = gimp_layer_to_selection;
+  item_class->default_name            = _("Layer");
+  item_class->rename_desc             = C_("undo-type", "Rename Layer");
+  item_class->translate_desc          = C_("undo-type", "Move Layer");
+  item_class->scale_desc              = C_("undo-type", "Scale Layer");
+  item_class->resize_desc             = C_("undo-type", "Resize Layer");
+  item_class->flip_desc               = C_("undo-type", "Flip Layer");
+  item_class->rotate_desc             = C_("undo-type", "Rotate Layer");
+  item_class->transform_desc          = C_("undo-type", "Transform Layer");
+  item_class->to_selection_desc       = C_("undo-type", "Alpha to Selection");
+  item_class->reorder_desc            = C_("undo-type", "Reorder Layer");
+  item_class->raise_desc              = C_("undo-type", "Raise Layer");
+  item_class->raise_to_top_desc       = C_("undo-type", "Raise Layer to Top");
+  item_class->lower_desc              = C_("undo-type", "Lower Layer");
+  item_class->lower_to_bottom_desc    = C_("undo-type", "Lower Layer to Bottom");
+  item_class->raise_failed            = _("Layer cannot be raised higher.");
+  item_class->lower_failed            = _("Layer cannot be lowered more.");
+
+  drawable_class->alpha_changed         = gimp_layer_alpha_changed;
+  drawable_class->estimate_memsize      = gimp_layer_estimate_memsize;
+  drawable_class->supports_alpha        = gimp_layer_supports_alpha;
+  drawable_class->convert_type          = gimp_layer_convert_type;
+  drawable_class->invalidate_boundary   = gimp_layer_invalidate_boundary;
+  drawable_class->get_active_components = gimp_layer_get_active_components;
+  drawable_class->get_active_mask       = gimp_layer_get_active_mask;
+  drawable_class->set_buffer            = gimp_layer_set_buffer;
+  drawable_class->get_bounding_box      = gimp_layer_get_bounding_box;
+
+  klass->opacity_changed              = NULL;
+  klass->mode_changed                 = NULL;
+  klass->blend_space_changed          = NULL;
+  klass->composite_space_changed      = NULL;
+  klass->composite_mode_changed       = NULL;
+  klass->excludes_backdrop_changed    = NULL;
+  klass->lock_alpha_changed           = NULL;
+  klass->mask_changed                 = NULL;
+  klass->apply_mask_changed           = NULL;
+  klass->edit_mask_changed            = NULL;
+  klass->show_mask_changed            = NULL;
+  klass->translate                    = gimp_layer_real_translate;
+  klass->scale                        = gimp_layer_real_scale;
+  klass->resize                       = gimp_layer_real_resize;
+  klass->flip                         = gimp_layer_real_flip;
+  klass->rotate                       = gimp_layer_real_rotate;
+  klass->transform                    = gimp_layer_real_transform;
+  klass->convert_type                 = gimp_layer_real_convert_type;
+  klass->get_bounding_box             = gimp_layer_real_get_bounding_box;
+  klass->get_effective_mode           = gimp_layer_real_get_effective_mode;
+  klass->get_excludes_backdrop        = gimp_layer_real_get_excludes_backdrop;
+
+  g_object_class_install_property (object_class, PROP_OPACITY,
+                                   g_param_spec_double ("opacity", NULL, NULL,
+                                                        GIMP_OPACITY_TRANSPARENT,
+                                                        GIMP_OPACITY_OPAQUE,
+                                                        GIMP_OPACITY_OPAQUE,
+                                                        GIMP_PARAM_READABLE));
+
+  g_object_class_install_property (object_class, PROP_MODE,
+                                   g_param_spec_enum ("mode", NULL, NULL,
+                                                      GIMP_TYPE_LAYER_MODE,
+                                                      GIMP_LAYER_MODE_NORMAL,
+                                                      GIMP_PARAM_READABLE));
+
+  g_object_class_install_property (object_class, PROP_BLEND_SPACE,
+                                   g_param_spec_enum ("blend-space",
+                                                      NULL, NULL,
+                                                      GIMP_TYPE_LAYER_COLOR_SPACE,
+                                                      GIMP_LAYER_COLOR_SPACE_AUTO,
+                                                      GIMP_PARAM_READABLE));
+
+  g_object_class_install_property (object_class, PROP_COMPOSITE_SPACE,
+                                   g_param_spec_enum ("composite-space",
+                                                      NULL, NULL,
+                                                      GIMP_TYPE_LAYER_COLOR_SPACE,
+                                                      GIMP_LAYER_COLOR_SPACE_AUTO,
+                                                      GIMP_PARAM_READABLE));
+
+  g_object_class_install_property (object_class, PROP_COMPOSITE_MODE,
+                                   g_param_spec_enum ("composite-mode",
+                                                      NULL, NULL,
+                                                      GIMP_TYPE_LAYER_COMPOSITE_MODE,
+                                                      GIMP_LAYER_COMPOSITE_AUTO,
+                                                      GIMP_PARAM_READABLE));
+
+  g_object_class_install_property (object_class, PROP_EXCLUDES_BACKDROP,
+                                   g_param_spec_boolean ("excludes-backdrop",
+                                                         NULL, NULL,
+                                                         FALSE,
+                                                         GIMP_PARAM_READABLE));
+
+  g_object_class_install_property (object_class, PROP_LOCK_ALPHA,
+                                   g_param_spec_boolean ("lock-alpha",
+                                                         NULL, NULL,
+                                                         FALSE,
+                                                         GIMP_PARAM_READABLE));
+
+  g_object_class_install_property (object_class, PROP_MASK,
+                                   g_param_spec_object ("mask",
+                                                        NULL, NULL,
+                                                        GIMP_TYPE_LAYER_MASK,
+                                                        GIMP_PARAM_READABLE));
+
+  g_object_class_install_property (object_class, PROP_FLOATING_SELECTION,
+                                   g_param_spec_boolean ("floating-selection",
+                                                         NULL, NULL,
+                                                         FALSE,
+                                                         GIMP_PARAM_READABLE));
+}
+
+static void
+gimp_layer_init (GimpLayer *layer)
+{
+  layer->opacity                   = GIMP_OPACITY_OPAQUE;
+  layer->mode                      = GIMP_LAYER_MODE_NORMAL;
+  layer->blend_space               = GIMP_LAYER_COLOR_SPACE_AUTO;
+  layer->composite_space           = GIMP_LAYER_COLOR_SPACE_AUTO;
+  layer->composite_mode            = GIMP_LAYER_COMPOSITE_AUTO;
+  layer->effective_mode            = layer->mode;
+  layer->effective_blend_space     = gimp_layer_get_real_blend_space (layer);
+  layer->effective_composite_space = gimp_layer_get_real_composite_space (layer);
+  layer->effective_composite_mode  = gimp_layer_get_real_composite_mode (layer);
+  layer->excludes_backdrop         = FALSE;
+  layer->lock_alpha                = FALSE;
+
+  layer->mask       = NULL;
+  layer->apply_mask = TRUE;
+  layer->edit_mask  = TRUE;
+  layer->show_mask  = FALSE;
+
+  /*  floating selection  */
+  layer->fs.drawable       = NULL;
+  layer->fs.boundary_known = FALSE;
+  layer->fs.segs           = NULL;
+  layer->fs.num_segs       = 0;
+}
+
+static void
+gimp_color_managed_iface_init (GimpColorManagedInterface *iface)
+{
+  iface->get_color_profile = gimp_layer_get_color_profile;
+}
+
+static void
+gimp_pickable_iface_init (GimpPickableInterface *iface)
+{
+  iface->get_opacity_at = gimp_layer_get_opacity_at;
+  iface->pixel_to_srgb  = gimp_layer_pixel_to_srgb;
+  iface->srgb_to_pixel  = gimp_layer_srgb_to_pixel;
+}
+
+static void
+gimp_layer_set_property (GObject      *object,
+                         guint         property_id,
+                         const GValue *value,
+                         GParamSpec   *pspec)
+{
+  switch (property_id)
+    {
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_layer_get_property (GObject    *object,
+                         guint       property_id,
+                         GValue     *value,
+                         GParamSpec *pspec)
+{
+  GimpLayer *layer = GIMP_LAYER (object);
+
+  switch (property_id)
+    {
+    case PROP_OPACITY:
+      g_value_set_double (value, gimp_layer_get_opacity (layer));
+      break;
+    case PROP_MODE:
+      g_value_set_enum (value, gimp_layer_get_mode (layer));
+      break;
+    case PROP_BLEND_SPACE:
+      g_value_set_enum (value, gimp_layer_get_blend_space (layer));
+      break;
+    case PROP_COMPOSITE_SPACE:
+      g_value_set_enum (value, gimp_layer_get_composite_space (layer));
+      break;
+    case PROP_COMPOSITE_MODE:
+      g_value_set_enum (value, gimp_layer_get_composite_mode (layer));
+      break;
+    case PROP_EXCLUDES_BACKDROP:
+      g_value_set_boolean (value, gimp_layer_get_excludes_backdrop (layer));
+      break;
+    case PROP_LOCK_ALPHA:
+      g_value_set_boolean (value, gimp_layer_get_lock_alpha (layer));
+      break;
+    case PROP_MASK:
+      g_value_set_object (value, gimp_layer_get_mask (layer));
+      break;
+    case PROP_FLOATING_SELECTION:
+      g_value_set_boolean (value, gimp_layer_is_floating_sel (layer));
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_layer_dispose (GObject *object)
+{
+  GimpLayer *layer = GIMP_LAYER (object);
+
+  if (layer->mask)
+    g_signal_handlers_disconnect_by_func (layer->mask,
+                                          gimp_layer_layer_mask_update,
+                                          layer);
+
+  if (gimp_layer_is_floating_sel (layer))
+    {
+      GimpDrawable *fs_drawable = gimp_layer_get_floating_sel_drawable (layer);
+
+      /* only detach if this is actually the drawable's fs because the
+       * layer might be on the undo stack and not attached to anything
+       */
+      if (gimp_drawable_get_floating_sel (fs_drawable) == layer)
+        gimp_drawable_detach_floating_sel (fs_drawable);
+
+      gimp_layer_set_floating_sel_drawable (layer, NULL);
+    }
+
+  G_OBJECT_CLASS (parent_class)->dispose (object);
+}
+
+static void
+gimp_layer_finalize (GObject *object)
+{
+  GimpLayer *layer = GIMP_LAYER (object);
+
+  g_clear_object (&layer->mask);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gimp_layer_update_mode_node (GimpLayer *layer)
+{
+  GeglNode               *mode_node;
+  GimpLayerMode           visible_mode;
+  GimpLayerColorSpace     visible_blend_space;
+  GimpLayerColorSpace     visible_composite_space;
+  GimpLayerCompositeMode  visible_composite_mode;
+
+  mode_node = gimp_drawable_get_mode_node (GIMP_DRAWABLE (layer));
+
+  if (layer->mask && layer->show_mask)
+    {
+      visible_mode            = GIMP_LAYER_MODE_NORMAL;
+      visible_blend_space     = GIMP_LAYER_COLOR_SPACE_AUTO;
+      visible_composite_space = GIMP_LAYER_COLOR_SPACE_AUTO;
+      visible_composite_mode  = GIMP_LAYER_COMPOSITE_AUTO;
+
+      /* This makes sure that masks of LEGACY-mode layers are
+       * composited in PERCEPTUAL space, and non-LEGACY layers in
+       * LINEAR space, or whatever composite space was chosen in the
+       * layer attributes dialog
+       */
+      visible_composite_space = gimp_layer_get_real_composite_space (layer);
+    }
+  else
+    {
+      visible_mode            = layer->effective_mode;
+      visible_blend_space     = layer->effective_blend_space;
+      visible_composite_space = layer->effective_composite_space;
+      visible_composite_mode  = layer->effective_composite_mode;
+    }
+
+  gimp_gegl_mode_node_set_mode (mode_node,
+                                visible_mode,
+                                visible_blend_space,
+                                visible_composite_space,
+                                visible_composite_mode);
+  gimp_gegl_mode_node_set_opacity (mode_node, layer->opacity);
+}
+
+static void
+gimp_layer_notify (GObject    *object,
+                   GParamSpec *pspec)
+{
+  if (! strcmp (pspec->name, "is-last-node") &&
+      gimp_filter_peek_node (GIMP_FILTER (object)))
+    {
+      gimp_layer_update_mode_node (GIMP_LAYER (object));
+
+      gimp_drawable_update (GIMP_DRAWABLE (object), 0, 0, -1, -1);
+    }
+}
+
+static void
+gimp_layer_name_changed (GimpObject *object)
+{
+  GimpLayer *layer = GIMP_LAYER (object);
+
+  if (GIMP_OBJECT_CLASS (parent_class)->name_changed)
+    GIMP_OBJECT_CLASS (parent_class)->name_changed (object);
+
+  if (layer->mask)
+    {
+      gchar *mask_name = g_strdup_printf (_("%s mask"),
+                                          gimp_object_get_name (object));
+
+      gimp_object_take_name (GIMP_OBJECT (layer->mask), mask_name);
+    }
+}
+
+static gint64
+gimp_layer_get_memsize (GimpObject *object,
+                        gint64     *gui_size)
+{
+  GimpLayer *layer   = GIMP_LAYER (object);
+  gint64     memsize = 0;
+
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (layer->mask), gui_size);
+
+  *gui_size += layer->fs.num_segs * sizeof (GimpBoundSeg);
+
+  return memsize + GIMP_OBJECT_CLASS (parent_class)->get_memsize (object,
+                                                                  gui_size);
+}
+
+static void
+gimp_layer_invalidate_preview (GimpViewable *viewable)
+{
+  GimpLayer *layer = GIMP_LAYER (viewable);
+
+  GIMP_VIEWABLE_CLASS (parent_class)->invalidate_preview (viewable);
+
+  if (gimp_layer_is_floating_sel (layer))
+    floating_sel_invalidate (layer);
+}
+
+static gchar *
+gimp_layer_get_description (GimpViewable  *viewable,
+                            gchar        **tooltip)
+{
+  if (gimp_layer_is_floating_sel (GIMP_LAYER (viewable)))
+    {
+      return g_strdup_printf (_("Floating Selection\n(%s)"),
+                              gimp_object_get_name (viewable));
+    }
+
+  return GIMP_VIEWABLE_CLASS (parent_class)->get_description (viewable,
+                                                              tooltip);
+}
+
+static GeglNode *
+gimp_layer_get_node (GimpFilter *filter)
+{
+  GimpDrawable *drawable = GIMP_DRAWABLE (filter);
+  GimpLayer    *layer    = GIMP_LAYER (filter);
+  GeglNode     *node;
+  GeglNode     *input;
+  GeglNode     *source;
+  GeglNode     *mode_node;
+  gboolean      source_node_hijacked = FALSE;
+
+  node = GIMP_FILTER_CLASS (parent_class)->get_node (filter);
+
+  input = gegl_node_get_input_proxy (node, "input");
+
+  source = gimp_drawable_get_source_node (drawable);
+
+  /* if the source node already has a parent, we are a floating
+   * selection and the source node has been hijacked by the fs'
+   * drawable
+   */
+  if (gegl_node_get_parent (source))
+    source_node_hijacked = TRUE;
+
+  if (! source_node_hijacked)
+    gegl_node_add_child (node, source);
+
+  gegl_node_connect_to (input,  "output",
+                        source, "input");
+
+  g_warn_if_fail (layer->layer_offset_node == NULL);
+  g_warn_if_fail (layer->mask_offset_node == NULL);
+
+  /* the mode node connects it all, and has aux and aux2 inputs for
+   * the layer and its mask
+   */
+  mode_node = gimp_drawable_get_mode_node (drawable);
+  gimp_layer_update_mode_node (layer);
+
+  /* the layer's offset node */
+  layer->layer_offset_node = gegl_node_new_child (node,
+                                                  "operation", "gegl:translate",
+                                                  NULL);
+  gimp_item_add_offset_node (GIMP_ITEM (layer), layer->layer_offset_node);
+
+  /* the layer mask's offset node */
+  layer->mask_offset_node = gegl_node_new_child (node,
+                                                 "operation", "gegl:translate",
+                                                  NULL);
+  gimp_item_add_offset_node (GIMP_ITEM (layer), layer->mask_offset_node);
+
+  if (! source_node_hijacked)
+    {
+      gegl_node_connect_to (source,                   "output",
+                            layer->layer_offset_node, "input");
+    }
+
+  if (! (layer->mask && gimp_layer_get_show_mask (layer)))
+    {
+      gegl_node_connect_to (layer->layer_offset_node, "output",
+                            mode_node,                "aux");
+    }
+
+  if (layer->mask)
+    {
+      GeglNode *mask;
+
+      mask = gimp_drawable_get_source_node (GIMP_DRAWABLE (layer->mask));
+
+      gegl_node_connect_to (mask,                    "output",
+                            layer->mask_offset_node, "input");
+
+      if (gimp_layer_get_show_mask (layer))
+        {
+          gegl_node_connect_to (layer->mask_offset_node, "output",
+                                mode_node,               "aux");
+        }
+      else if (gimp_layer_get_apply_mask (layer))
+        {
+          gegl_node_connect_to (layer->mask_offset_node, "output",
+                                mode_node,               "aux2");
+        }
+    }
+
+  return node;
+}
+
+static void
+gimp_layer_removed (GimpItem *item)
+{
+  GimpLayer *layer = GIMP_LAYER (item);
+
+  if (layer->mask)
+    gimp_item_removed (GIMP_ITEM (layer->mask));
+
+  if (GIMP_ITEM_CLASS (parent_class)->removed)
+    GIMP_ITEM_CLASS (parent_class)->removed (item);
+}
+
+static void
+gimp_layer_unset_removed (GimpItem *item)
+{
+  GimpLayer *layer = GIMP_LAYER (item);
+
+  if (layer->mask)
+    gimp_item_unset_removed (GIMP_ITEM (layer->mask));
+
+  if (GIMP_ITEM_CLASS (parent_class)->unset_removed)
+    GIMP_ITEM_CLASS (parent_class)->unset_removed (item);
+}
+
+static gboolean
+gimp_layer_is_attached (GimpItem *item)
+{
+  GimpImage *image = gimp_item_get_image (item);
+
+  return (GIMP_IS_IMAGE (image) &&
+          gimp_container_have (gimp_image_get_layers (image),
+                               GIMP_OBJECT (item)));
+}
+
+static GimpItemTree *
+gimp_layer_get_tree (GimpItem *item)
+{
+  if (gimp_item_is_attached (item))
+    {
+      GimpImage *image = gimp_item_get_image (item);
+
+      return gimp_image_get_layer_tree (image);
+    }
+
+  return NULL;
+}
+
+static GimpItem *
+gimp_layer_duplicate (GimpItem *item,
+                      GType     new_type)
+{
+  GimpItem *new_item;
+
+  g_return_val_if_fail (g_type_is_a (new_type, GIMP_TYPE_DRAWABLE), NULL);
+
+  new_item = GIMP_ITEM_CLASS (parent_class)->duplicate (item, new_type);
+
+  if (GIMP_IS_LAYER (new_item))
+    {
+      GimpLayer *layer     = GIMP_LAYER (item);
+      GimpLayer *new_layer = GIMP_LAYER (new_item);
+
+      gimp_layer_set_mode            (new_layer,
+                                      gimp_layer_get_mode (layer), FALSE);
+      gimp_layer_set_blend_space     (new_layer,
+                                      gimp_layer_get_blend_space (layer), FALSE);
+      gimp_layer_set_composite_space (new_layer,
+                                      gimp_layer_get_composite_space (layer), FALSE);
+      gimp_layer_set_composite_mode  (new_layer,
+                                      gimp_layer_get_composite_mode (layer), FALSE);
+      gimp_layer_set_opacity         (new_layer,
+                                      gimp_layer_get_opacity (layer), FALSE);
+
+      if (gimp_layer_can_lock_alpha (new_layer))
+        gimp_layer_set_lock_alpha (new_layer,
+                                   gimp_layer_get_lock_alpha (layer), FALSE);
+
+      /*  duplicate the layer mask if necessary  */
+      if (layer->mask)
+        {
+          GimpItem *mask;
+
+          mask = gimp_item_duplicate (GIMP_ITEM (layer->mask),
+                                      G_TYPE_FROM_INSTANCE (layer->mask));
+          gimp_layer_add_mask (new_layer, GIMP_LAYER_MASK (mask), FALSE, NULL);
+
+          new_layer->apply_mask = layer->apply_mask;
+          new_layer->edit_mask  = layer->edit_mask;
+          new_layer->show_mask  = layer->show_mask;
+        }
+    }
+
+  return new_item;
+}
+
+static void
+gimp_layer_convert (GimpItem  *item,
+                    GimpImage *dest_image,
+                    GType      old_type)
+{
+  GimpLayer         *layer    = GIMP_LAYER (item);
+  GimpDrawable      *drawable = GIMP_DRAWABLE (item);
+  GimpImageBaseType  old_base_type;
+  GimpImageBaseType  new_base_type;
+  GimpPrecision      old_precision;
+  GimpPrecision      new_precision;
+  GimpColorProfile  *dest_profile = NULL;
+
+  old_base_type = gimp_drawable_get_base_type (drawable);
+  new_base_type = gimp_image_get_base_type (dest_image);
+
+  old_precision = gimp_drawable_get_precision (drawable);
+  new_precision = gimp_image_get_precision (dest_image);
+
+  if (g_type_is_a (old_type, GIMP_TYPE_LAYER) &&
+      gimp_image_get_is_color_managed (dest_image))
+    {
+      GimpColorProfile *src_profile =
+        gimp_color_managed_get_color_profile (GIMP_COLOR_MANAGED (item));
+
+      dest_profile =
+        gimp_color_managed_get_color_profile (GIMP_COLOR_MANAGED (dest_image));
+
+      if (gimp_color_profile_is_equal (dest_profile, src_profile))
+        dest_profile = NULL;
+    }
+
+  if (old_base_type != new_base_type ||
+      old_precision != new_precision ||
+      dest_profile)
+    {
+      gimp_drawable_convert_type (drawable, dest_image,
+                                  new_base_type,
+                                  new_precision,
+                                  gimp_drawable_has_alpha (drawable),
+                                  dest_profile,
+                                  GEGL_DITHER_NONE, GEGL_DITHER_NONE,
+                                  FALSE, NULL);
+    }
+
+  if (layer->mask)
+    gimp_item_set_image (GIMP_ITEM (layer->mask), dest_image);
+
+  GIMP_ITEM_CLASS (parent_class)->convert (item, dest_image, old_type);
+}
+
+static gboolean
+gimp_layer_rename (GimpItem     *item,
+                   const gchar  *new_name,
+                   const gchar  *undo_desc,
+                   GError      **error)
+{
+  GimpLayer *layer = GIMP_LAYER (item);
+  GimpImage *image = gimp_item_get_image (item);
+  gboolean   attached;
+  gboolean   floating_sel;
+
+  attached     = gimp_item_is_attached (item);
+  floating_sel = gimp_layer_is_floating_sel (layer);
+
+  if (floating_sel)
+    {
+      if (GIMP_IS_CHANNEL (gimp_layer_get_floating_sel_drawable (layer)))
+        {
+          g_set_error_literal (error, GIMP_ERROR, GIMP_FAILED,
+                               _("Cannot create a new layer from the floating "
+                                 "selection because it belongs to a layer mask "
+                                 "or channel."));
+          return FALSE;
+        }
+
+      if (attached)
+        {
+          gimp_image_undo_group_start (image,
+                                       GIMP_UNDO_GROUP_ITEM_PROPERTIES,
+                                       undo_desc);
+
+          floating_sel_to_layer (layer, NULL);
+        }
+    }
+
+  GIMP_ITEM_CLASS (parent_class)->rename (item, new_name, undo_desc, error);
+
+  if (attached && floating_sel)
+    gimp_image_undo_group_end (image);
+
+  return TRUE;
+}
+
+static void
+gimp_layer_start_move (GimpItem *item,
+                       gboolean  push_undo)
+{
+  GimpLayer *layer     = GIMP_LAYER (item);
+  GimpLayer *ancestor  = layer;
+  GSList    *ancestors = NULL;
+
+  /* suspend mask cropping for all of the layer's ancestors */
+  while ((ancestor = gimp_layer_get_parent (ancestor)))
+    {
+      gimp_group_layer_suspend_mask (GIMP_GROUP_LAYER (ancestor), push_undo);
+
+      ancestors = g_slist_prepend (ancestors, g_object_ref (ancestor));
+    }
+
+  /* we keep the ancestor list around, so that we can resume mask cropping for
+   * the same set of groups in gimp_layer_end_move().  note that
+   * gimp_image_remove_layer() calls start_move() before removing the layer,
+   * while it's still part of the layer tree, and end_move() afterwards, when
+   * it's no longer part of the layer tree, and hence we can't use get_parent()
+   * in end_move() to get the same set of ancestors.
+   */
+  layer->move_stack = g_slist_prepend (layer->move_stack, ancestors);
+
+  if (GIMP_ITEM_CLASS (parent_class)->start_move)
+    GIMP_ITEM_CLASS (parent_class)->start_move (item, push_undo);
+}
+
+static void
+gimp_layer_end_move (GimpItem *item,
+                     gboolean  push_undo)
+{
+  GimpLayer *layer = GIMP_LAYER (item);
+  GSList    *ancestors;
+  GSList    *iter;
+
+  g_return_if_fail (layer->move_stack != NULL);
+
+  if (GIMP_ITEM_CLASS (parent_class)->end_move)
+    GIMP_ITEM_CLASS (parent_class)->end_move (item, push_undo);
+
+  ancestors = layer->move_stack->data;
+
+  layer->move_stack = g_slist_remove (layer->move_stack, ancestors);
+
+  /* resume mask cropping for all of the layer's ancestors */
+  for (iter = ancestors; iter; iter = g_slist_next (iter))
+    {
+      GimpGroupLayer *ancestor = iter->data;
+
+      gimp_group_layer_resume_mask (ancestor, push_undo);
+
+      g_object_unref (ancestor);
+    }
+
+  g_slist_free (ancestors);
+}
+
+static void
+gimp_layer_translate (GimpItem *item,
+                      gdouble   offset_x,
+                      gdouble   offset_y,
+                      gboolean  push_undo)
+{
+  GimpLayer *layer = GIMP_LAYER (item);
+
+  if (push_undo)
+    gimp_image_undo_push_item_displace (gimp_item_get_image (item), NULL, item);
+
+  GIMP_LAYER_GET_CLASS (layer)->translate (layer,
+                                           SIGNED_ROUND (offset_x),
+                                           SIGNED_ROUND (offset_y));
+
+  if (layer->mask)
+    {
+      gint off_x, off_y;
+
+      gimp_item_get_offset (item, &off_x, &off_y);
+      gimp_item_set_offset (GIMP_ITEM (layer->mask), off_x, off_y);
+
+      gimp_viewable_invalidate_preview (GIMP_VIEWABLE (layer->mask));
+    }
+}
+
+static void
+gimp_layer_scale (GimpItem              *item,
+                  gint                   new_width,
+                  gint                   new_height,
+                  gint                   new_offset_x,
+                  gint                   new_offset_y,
+                  GimpInterpolationType  interpolation_type,
+                  GimpProgress          *progress)
+{
+  GimpLayer       *layer = GIMP_LAYER (item);
+  GimpObjectQueue *queue = NULL;
+
+  if (progress && layer->mask)
+    {
+      GimpLayerMask *mask;
+
+      queue    = gimp_object_queue_new (progress);
+      progress = GIMP_PROGRESS (queue);
+
+      /* temporarily set layer->mask to NULL, so that its size won't be counted
+       * when pushing the layer to the queue.
+       */
+      mask        = layer->mask;
+      layer->mask = NULL;
+
+      gimp_object_queue_push (queue, layer);
+      gimp_object_queue_push (queue, mask);
+
+      layer->mask = mask;
+    }
+
+  if (queue)
+    gimp_object_queue_pop (queue);
+
+  GIMP_LAYER_GET_CLASS (layer)->scale (layer, new_width, new_height,
+                                       new_offset_x, new_offset_y,
+                                       interpolation_type, progress);
+
+  if (layer->mask)
+    {
+      if (queue)
+        gimp_object_queue_pop (queue);
+
+      gimp_item_scale (GIMP_ITEM (layer->mask),
+                       new_width, new_height,
+                       new_offset_x, new_offset_y,
+                       interpolation_type, progress);
+    }
+
+  g_clear_object (&queue);
+}
+
+static void
+gimp_layer_resize (GimpItem     *item,
+                   GimpContext  *context,
+                   GimpFillType  fill_type,
+                   gint          new_width,
+                   gint          new_height,
+                   gint          offset_x,
+                   gint          offset_y)
+{
+  GimpLayer *layer  = GIMP_LAYER (item);
+
+  GIMP_LAYER_GET_CLASS (layer)->resize (layer, context, fill_type,
+                                        new_width, new_height,
+                                        offset_x, offset_y);
+
+  if (layer->mask)
+    gimp_item_resize (GIMP_ITEM (layer->mask), context, GIMP_FILL_TRANSPARENT,
+                      new_width, new_height, offset_x, offset_y);
+}
+
+static void
+gimp_layer_flip (GimpItem            *item,
+                 GimpContext         *context,
+                 GimpOrientationType  flip_type,
+                 gdouble              axis,
+                 gboolean             clip_result)
+{
+  GimpLayer *layer = GIMP_LAYER (item);
+
+  GIMP_LAYER_GET_CLASS (layer)->flip (layer, context, flip_type, axis,
+                                      clip_result);
+
+  if (layer->mask)
+    gimp_item_flip (GIMP_ITEM (layer->mask), context,
+                    flip_type, axis, clip_result);
+}
+
+static void
+gimp_layer_rotate (GimpItem         *item,
+                   GimpContext      *context,
+                   GimpRotationType  rotate_type,
+                   gdouble           center_x,
+                   gdouble           center_y,
+                   gboolean          clip_result)
+{
+  GimpLayer *layer = GIMP_LAYER (item);
+
+  GIMP_LAYER_GET_CLASS (layer)->rotate (layer, context,
+                                        rotate_type, center_x, center_y,
+                                        clip_result);
+
+  if (layer->mask)
+    gimp_item_rotate (GIMP_ITEM (layer->mask), context,
+                      rotate_type, center_x, center_y, clip_result);
+}
+
+static void
+gimp_layer_transform (GimpItem               *item,
+                      GimpContext            *context,
+                      const GimpMatrix3      *matrix,
+                      GimpTransformDirection  direction,
+                      GimpInterpolationType   interpolation_type,
+                      GimpTransformResize     clip_result,
+                      GimpProgress           *progress)
+{
+  GimpLayer       *layer = GIMP_LAYER (item);
+  GimpObjectQueue *queue = NULL;
+
+  if (progress && layer->mask)
+    {
+      GimpLayerMask *mask;
+
+      queue    = gimp_object_queue_new (progress);
+      progress = GIMP_PROGRESS (queue);
+
+      /* temporarily set layer->mask to NULL, so that its size won't be counted
+       * when pushing the layer to the queue.
+       */
+      mask        = layer->mask;
+      layer->mask = NULL;
+
+      gimp_object_queue_push (queue, layer);
+      gimp_object_queue_push (queue, mask);
+
+      layer->mask = mask;
+    }
+
+  if (queue)
+    gimp_object_queue_pop (queue);
+
+  GIMP_LAYER_GET_CLASS (layer)->transform (layer, context, matrix, direction,
+                                           interpolation_type,
+                                           clip_result,
+                                           progress);
+
+  if (layer->mask)
+    {
+      if (queue)
+        gimp_object_queue_pop (queue);
+
+      gimp_item_transform (GIMP_ITEM (layer->mask), context,
+                           matrix, direction,
+                           interpolation_type,
+                           clip_result, progress);
+    }
+
+  g_clear_object (&queue);
+}
+
+static void
+gimp_layer_to_selection (GimpItem       *item,
+                         GimpChannelOps  op,
+                         gboolean        antialias,
+                         gboolean        feather,
+                         gdouble         feather_radius_x,
+                         gdouble         feather_radius_y)
+{
+  GimpLayer *layer = GIMP_LAYER (item);
+  GimpImage *image = gimp_item_get_image (item);
+
+  gimp_channel_select_alpha (gimp_image_get_mask (image),
+                             GIMP_DRAWABLE (layer),
+                             op,
+                             feather, feather_radius_x, feather_radius_y);
+}
+
+static void
+gimp_layer_alpha_changed (GimpDrawable *drawable)
+{
+  if (GIMP_DRAWABLE_CLASS (parent_class)->alpha_changed)
+    GIMP_DRAWABLE_CLASS (parent_class)->alpha_changed (drawable);
+
+  /* When we add/remove alpha, whatever cached color transforms in
+   * view renderers need to be recreated because they cache the wrong
+   * lcms formats. See bug 478528.
+   */
+  gimp_color_managed_profile_changed (GIMP_COLOR_MANAGED (drawable));
+}
+
+static gint64
+gimp_layer_estimate_memsize (GimpDrawable      *drawable,
+                             GimpComponentType  component_type,
+                             gint               width,
+                             gint               height)
+{
+  GimpLayer *layer   = GIMP_LAYER (drawable);
+  gint64     memsize = 0;
+
+  if (layer->mask)
+    memsize += gimp_drawable_estimate_memsize (GIMP_DRAWABLE (layer->mask),
+                                               component_type,
+                                               width, height);
+
+  return memsize +
+         GIMP_DRAWABLE_CLASS (parent_class)->estimate_memsize (drawable,
+                                                               component_type,
+                                                               width, height);
+}
+
+static gboolean
+gimp_layer_supports_alpha (GimpDrawable *drawable)
+{
+  return TRUE;
+}
+
+static void
+gimp_layer_convert_type (GimpDrawable     *drawable,
+                         GimpImage        *dest_image,
+                         const Babl       *new_format,
+                         GimpColorProfile *dest_profile,
+                         GeglDitherMethod  layer_dither_type,
+                         GeglDitherMethod  mask_dither_type,
+                         gboolean          push_undo,
+                         GimpProgress     *progress)
+{
+  GimpLayer       *layer = GIMP_LAYER (drawable);
+  GimpObjectQueue *queue = NULL;
+  gboolean         convert_mask;
+
+  convert_mask = layer->mask &&
+                 gimp_babl_format_get_precision (new_format) !=
+                 gimp_drawable_get_precision (GIMP_DRAWABLE (layer->mask));
+
+  if (progress && convert_mask)
+    {
+      GimpLayerMask *mask;
+
+      queue    = gimp_object_queue_new (progress);
+      progress = GIMP_PROGRESS (queue);
+
+      /* temporarily set layer->mask to NULL, so that its size won't be counted
+       * when pushing the layer to the queue.
+       */
+      mask        = layer->mask;
+      layer->mask = NULL;
+
+      gimp_object_queue_push (queue, layer);
+      gimp_object_queue_push (queue, mask);
+
+      layer->mask = mask;
+    }
+
+  if (queue)
+    gimp_object_queue_pop (queue);
+
+  GIMP_LAYER_GET_CLASS (layer)->convert_type (layer, dest_image, new_format,
+                                              dest_profile, layer_dither_type,
+                                              mask_dither_type, push_undo,
+                                              progress);
+
+  if (convert_mask)
+    {
+      if (queue)
+        gimp_object_queue_pop (queue);
+
+      gimp_drawable_convert_type (GIMP_DRAWABLE (layer->mask), dest_image,
+                                  GIMP_GRAY,
+                                  gimp_babl_format_get_precision (new_format),
+                                  gimp_drawable_has_alpha (GIMP_DRAWABLE (layer->mask)),
+                                  NULL,
+                                  layer_dither_type, mask_dither_type,
+                                  push_undo, progress);
+    }
+
+  g_clear_object (&queue);
+}
+
+static void
+gimp_layer_invalidate_boundary (GimpDrawable *drawable)
+{
+  GimpLayer *layer = GIMP_LAYER (drawable);
+
+  if (gimp_item_is_attached (GIMP_ITEM (drawable)) &&
+      gimp_item_is_visible (GIMP_ITEM (drawable)))
+    {
+      GimpImage   *image = gimp_item_get_image (GIMP_ITEM (drawable));
+      GimpChannel *mask  = gimp_image_get_mask (image);
+
+      /*  Turn the current selection off  */
+      gimp_image_selection_invalidate (image);
+
+      /*  Only bother with the bounds if there is a selection  */
+      if (! gimp_channel_is_empty (mask))
+        {
+          mask->bounds_known   = FALSE;
+          mask->boundary_known = FALSE;
+        }
+    }
+
+  if (gimp_layer_is_floating_sel (layer))
+    floating_sel_invalidate (layer);
+}
+
+static void
+gimp_layer_get_active_components (GimpDrawable *drawable,
+                                  gboolean     *active)
+{
+  GimpLayer  *layer  = GIMP_LAYER (drawable);
+  GimpImage  *image  = gimp_item_get_image (GIMP_ITEM (drawable));
+  const Babl *format = gimp_drawable_get_format (drawable);
+
+  /*  first copy the image active channels  */
+  gimp_image_get_active_array (image, active);
+
+  if (gimp_drawable_has_alpha (drawable) && layer->lock_alpha)
+    active[babl_format_get_n_components (format) - 1] = FALSE;
+}
+
+static GimpComponentMask
+gimp_layer_get_active_mask (GimpDrawable *drawable)
+{
+  GimpLayer         *layer = GIMP_LAYER (drawable);
+  GimpImage         *image = gimp_item_get_image (GIMP_ITEM (drawable));
+  GimpComponentMask  mask  = gimp_image_get_active_mask (image);
+
+  if (gimp_drawable_has_alpha (drawable) && layer->lock_alpha)
+    mask &= ~GIMP_COMPONENT_MASK_ALPHA;
+
+  return mask;
+}
+
+static void
+gimp_layer_set_buffer (GimpDrawable        *drawable,
+                       gboolean             push_undo,
+                       const gchar         *undo_desc,
+                       GeglBuffer          *buffer,
+                       const GeglRectangle *bounds)
+{
+  GeglBuffer *old_buffer = gimp_drawable_get_buffer (drawable);
+  gint        old_linear = -1;
+
+  if (old_buffer)
+    old_linear = gimp_drawable_get_linear (drawable);
+
+  GIMP_DRAWABLE_CLASS (parent_class)->set_buffer (drawable,
+                                                  push_undo, undo_desc,
+                                                  buffer, bounds);
+
+  if (gimp_filter_peek_node (GIMP_FILTER (drawable)))
+    {
+      if (gimp_drawable_get_linear (drawable) != old_linear)
+        gimp_layer_update_mode_node (GIMP_LAYER (drawable));
+    }
+}
+
+static GeglRectangle
+gimp_layer_get_bounding_box (GimpDrawable *drawable)
+{
+  GimpLayer     *layer = GIMP_LAYER (drawable);
+  GimpLayerMask *mask  = gimp_layer_get_mask (layer);
+  GeglRectangle  bounding_box;
+
+  if (mask && gimp_layer_get_show_mask (layer))
+    {
+      bounding_box = gimp_drawable_get_bounding_box (GIMP_DRAWABLE (mask));
+    }
+  else
+    {
+      bounding_box = GIMP_LAYER_GET_CLASS (layer)->get_bounding_box (layer);
+
+      if (mask && gimp_layer_get_apply_mask (layer))
+        {
+          GeglRectangle mask_bounding_box;
+
+          mask_bounding_box = gimp_drawable_get_bounding_box (
+            GIMP_DRAWABLE (mask));
+
+          gegl_rectangle_intersect (&bounding_box,
+                                    &bounding_box, &mask_bounding_box);
+        }
+    }
+
+  return bounding_box;
+}
+
+static GimpColorProfile *
+gimp_layer_get_color_profile (GimpColorManaged *managed)
+{
+  GimpImage *image = gimp_item_get_image (GIMP_ITEM (managed));
+
+  return gimp_color_managed_get_color_profile (GIMP_COLOR_MANAGED (image));
+}
+
+static gdouble
+gimp_layer_get_opacity_at (GimpPickable *pickable,
+                           gint          x,
+                           gint          y)
+{
+  GimpLayer *layer = GIMP_LAYER (pickable);
+  gdouble    value = GIMP_OPACITY_TRANSPARENT;
+
+  if (x >= 0 && x < gimp_item_get_width  (GIMP_ITEM (layer)) &&
+      y >= 0 && y < gimp_item_get_height (GIMP_ITEM (layer)) &&
+      gimp_item_is_visible (GIMP_ITEM (layer)))
+    {
+      if (! gimp_drawable_has_alpha (GIMP_DRAWABLE (layer)))
+        {
+          value = GIMP_OPACITY_OPAQUE;
+        }
+      else
+        {
+          gegl_buffer_sample (gimp_drawable_get_buffer (GIMP_DRAWABLE (layer)),
+                              x, y, NULL, &value, babl_format ("A double"),
+                              GEGL_SAMPLER_NEAREST, GEGL_ABYSS_NONE);
+        }
+
+      if (gimp_layer_get_mask (layer) &&
+          gimp_layer_get_apply_mask (layer))
+        {
+          gdouble mask_value;
+
+          mask_value = gimp_pickable_get_opacity_at (GIMP_PICKABLE (layer->mask),
+                                                     x, y);
+
+          value *= mask_value;
+        }
+    }
+
+  return value;
+}
+
+static void
+gimp_layer_pixel_to_srgb (GimpPickable *pickable,
+                          const Babl   *format,
+                          gpointer      pixel,
+                          GimpRGB      *color)
+{
+  GimpImage *image = gimp_item_get_image (GIMP_ITEM (pickable));
+
+  gimp_pickable_pixel_to_srgb (GIMP_PICKABLE (image), format, pixel, color);
+}
+
+static void
+gimp_layer_srgb_to_pixel (GimpPickable  *pickable,
+                          const GimpRGB *color,
+                          const Babl    *format,
+                          gpointer       pixel)
+{
+  GimpImage *image = gimp_item_get_image (GIMP_ITEM (pickable));
+
+  gimp_pickable_srgb_to_pixel (GIMP_PICKABLE (image), color, format, pixel);
+}
+
+static void
+gimp_layer_real_translate (GimpLayer *layer,
+                           gint       offset_x,
+                           gint       offset_y)
+{
+  /*  update the old region  */
+  gimp_drawable_update (GIMP_DRAWABLE (layer), 0, 0, -1, -1);
+
+  /*  invalidate the selection boundary because of a layer modification  */
+  gimp_drawable_invalidate_boundary (GIMP_DRAWABLE (layer));
+
+  GIMP_ITEM_CLASS (parent_class)->translate (GIMP_ITEM (layer),
+                                             offset_x, offset_y,
+                                             FALSE);
+
+  /*  update the new region  */
+  gimp_drawable_update (GIMP_DRAWABLE (layer), 0, 0, -1, -1);
+}
+
+static void
+gimp_layer_real_scale (GimpLayer             *layer,
+                       gint                   new_width,
+                       gint                   new_height,
+                       gint                   new_offset_x,
+                       gint                   new_offset_y,
+                       GimpInterpolationType  interpolation_type,
+                       GimpProgress          *progress)
+{
+  GIMP_ITEM_CLASS (parent_class)->scale (GIMP_ITEM (layer),
+                                         new_width, new_height,
+                                         new_offset_x, new_offset_y,
+                                         interpolation_type, progress);
+}
+
+static void
+gimp_layer_real_resize (GimpLayer    *layer,
+                        GimpContext  *context,
+                        GimpFillType  fill_type,
+                        gint          new_width,
+                        gint          new_height,
+                        gint          offset_x,
+                        gint          offset_y)
+{
+  if (fill_type == GIMP_FILL_TRANSPARENT &&
+      ! gimp_drawable_has_alpha (GIMP_DRAWABLE (layer)))
+    {
+      fill_type = GIMP_FILL_BACKGROUND;
+    }
+
+  GIMP_ITEM_CLASS (parent_class)->resize (GIMP_ITEM (layer),
+                                          context, fill_type,
+                                          new_width, new_height,
+                                          offset_x, offset_y);
+}
+
+static void
+gimp_layer_real_flip (GimpLayer           *layer,
+                      GimpContext         *context,
+                      GimpOrientationType  flip_type,
+                      gdouble              axis,
+                      gboolean             clip_result)
+{
+  GIMP_ITEM_CLASS (parent_class)->flip (GIMP_ITEM (layer),
+                                        context, flip_type, axis, clip_result);
+}
+
+static void
+gimp_layer_real_rotate (GimpLayer        *layer,
+                        GimpContext      *context,
+                        GimpRotationType  rotate_type,
+                        gdouble           center_x,
+                        gdouble           center_y,
+                        gboolean          clip_result)
+{
+  GIMP_ITEM_CLASS (parent_class)->rotate (GIMP_ITEM (layer),
+                                          context, rotate_type,
+                                          center_x, center_y,
+                                          clip_result);
+}
+
+static void
+gimp_layer_real_transform (GimpLayer              *layer,
+                           GimpContext            *context,
+                           const GimpMatrix3      *matrix,
+                           GimpTransformDirection  direction,
+                           GimpInterpolationType   interpolation_type,
+                           GimpTransformResize     clip_result,
+                           GimpProgress           *progress)
+{
+  /* FIXME: make interpolated transformations work on layers without alpha */
+  if (interpolation_type != GIMP_INTERPOLATION_NONE &&
+      ! gimp_drawable_has_alpha (GIMP_DRAWABLE (layer)))
+    gimp_layer_add_alpha (layer);
+
+  GIMP_ITEM_CLASS (parent_class)->transform (GIMP_ITEM (layer),
+                                             context, matrix, direction,
+                                             interpolation_type,
+                                             clip_result,
+                                             progress);
+}
+
+static void
+gimp_layer_real_convert_type (GimpLayer        *layer,
+                              GimpImage        *dest_image,
+                              const Babl       *new_format,
+                              GimpColorProfile *dest_profile,
+                              GeglDitherMethod  layer_dither_type,
+                              GeglDitherMethod  mask_dither_type,
+                              gboolean          push_undo,
+                              GimpProgress     *progress)
+{
+  GimpDrawable *drawable = GIMP_DRAWABLE (layer);
+  GeglBuffer   *src_buffer;
+  GeglBuffer   *dest_buffer;
+
+  if (layer_dither_type == GEGL_DITHER_NONE)
+    {
+      src_buffer = g_object_ref (gimp_drawable_get_buffer (drawable));
+    }
+  else
+    {
+      gint bits;
+
+      src_buffer =
+        gegl_buffer_new (GEGL_RECTANGLE (0, 0,
+                                         gimp_item_get_width  (GIMP_ITEM (layer)),
+                                         gimp_item_get_height (GIMP_ITEM (layer))),
+                         gimp_drawable_get_format (drawable));
+
+      bits = (babl_format_get_bytes_per_pixel (new_format) * 8 /
+              babl_format_get_n_components (new_format));
+
+      gimp_gegl_apply_dither (gimp_drawable_get_buffer (drawable),
+                              NULL, NULL,
+                              src_buffer, 1 << bits, layer_dither_type);
+    }
+
+  dest_buffer =
+    gegl_buffer_new (GEGL_RECTANGLE (0, 0,
+                                     gimp_item_get_width  (GIMP_ITEM (layer)),
+                                     gimp_item_get_height (GIMP_ITEM (layer))),
+                     new_format);
+
+  if (dest_profile)
+    {
+      GimpColorProfile *src_profile =
+        gimp_color_managed_get_color_profile (GIMP_COLOR_MANAGED (layer));
+
+      gimp_gegl_convert_color_profile (src_buffer,  NULL, src_profile,
+                                       dest_buffer, NULL, dest_profile,
+                                       GIMP_COLOR_RENDERING_INTENT_PERCEPTUAL,
+                                       TRUE, progress);
+    }
+  else
+    {
+      gimp_gegl_buffer_copy (src_buffer, NULL, GEGL_ABYSS_NONE,
+                             dest_buffer, NULL);
+    }
+
+  gimp_drawable_set_buffer (drawable, push_undo, NULL, dest_buffer);
+
+  g_object_unref (src_buffer);
+  g_object_unref (dest_buffer);
+}
+
+static GeglRectangle
+gimp_layer_real_get_bounding_box (GimpLayer *layer)
+{
+  return GIMP_DRAWABLE_CLASS (parent_class)->get_bounding_box (
+    GIMP_DRAWABLE (layer));
+}
+
+static void
+gimp_layer_real_get_effective_mode (GimpLayer              *layer,
+                                    GimpLayerMode          *mode,
+                                    GimpLayerColorSpace    *blend_space,
+                                    GimpLayerColorSpace    *composite_space,
+                                    GimpLayerCompositeMode *composite_mode)
+{
+  *mode            = gimp_layer_get_mode (layer);
+  *blend_space     = gimp_layer_get_real_blend_space (layer);
+  *composite_space = gimp_layer_get_real_composite_space (layer);
+  *composite_mode  = gimp_layer_get_real_composite_mode (layer);
+}
+
+static gboolean
+gimp_layer_real_get_excludes_backdrop (GimpLayer *layer)
+{
+  GimpLayerCompositeRegion included_region;
+
+  included_region = gimp_layer_mode_get_included_region (layer->mode,
+                                                         layer->effective_composite_mode);
+
+  return ! (included_region & GIMP_LAYER_COMPOSITE_REGION_DESTINATION);
+}
+
+static void
+gimp_layer_layer_mask_update (GimpDrawable *drawable,
+                              gint          x,
+                              gint          y,
+                              gint          width,
+                              gint          height,
+                              GimpLayer    *layer)
+{
+  if (gimp_layer_get_apply_mask (layer) ||
+      gimp_layer_get_show_mask (layer))
+    {
+      gimp_drawable_update (GIMP_DRAWABLE (layer),
+                            x, y, width, height);
+    }
+}
+
+
+/*  public functions  */
+
+GimpLayer *
+gimp_layer_get_parent (GimpLayer *layer)
+{
+  g_return_val_if_fail (GIMP_IS_LAYER (layer), NULL);
+
+  return GIMP_LAYER (gimp_viewable_get_parent (GIMP_VIEWABLE (layer)));
+}
+
+GimpLayerMask *
+gimp_layer_get_mask (GimpLayer *layer)
+{
+  g_return_val_if_fail (GIMP_IS_LAYER (layer), NULL);
+
+  return layer->mask;
+}
+
+GimpLayerMask *
+gimp_layer_add_mask (GimpLayer      *layer,
+                     GimpLayerMask  *mask,
+                     gboolean        push_undo,
+                     GError        **error)
+{
+  GimpImage *image;
+
+  g_return_val_if_fail (GIMP_IS_LAYER (layer), NULL);
+  g_return_val_if_fail (GIMP_IS_LAYER_MASK (mask), NULL);
+  g_return_val_if_fail (gimp_item_get_image (GIMP_ITEM (layer)) ==
+                        gimp_item_get_image (GIMP_ITEM (mask)), NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, NULL);
+
+  if (! gimp_item_is_attached (GIMP_ITEM (layer)))
+    push_undo = FALSE;
+
+  image = gimp_item_get_image (GIMP_ITEM (layer));
+
+  if (layer->mask)
+    {
+      g_set_error_literal (error, GIMP_ERROR, GIMP_FAILED,
+                           _("Unable to add a layer mask since "
+                             "the layer already has one."));
+      return NULL;
+    }
+
+  if ((gimp_item_get_width (GIMP_ITEM (layer)) !=
+       gimp_item_get_width (GIMP_ITEM (mask))) ||
+      (gimp_item_get_height (GIMP_ITEM (layer)) !=
+       gimp_item_get_height (GIMP_ITEM (mask))))
+    {
+      g_set_error_literal (error, GIMP_ERROR, GIMP_FAILED,
+                           _("Cannot add layer mask of different "
+                             "dimensions than specified layer."));
+      return NULL;
+    }
+
+  if (push_undo)
+    gimp_image_undo_push_layer_mask_add (image, C_("undo-type", "Add Layer Mask"),
+                                         layer, mask);
+
+  layer->mask = g_object_ref_sink (mask);
+  layer->apply_mask = TRUE;
+  layer->edit_mask  = TRUE;
+  layer->show_mask  = FALSE;
+
+  gimp_layer_mask_set_layer (mask, layer);
+
+  if (gimp_filter_peek_node (GIMP_FILTER (layer)))
+    {
+      GeglNode *mode_node;
+      GeglNode *mask;
+
+      mode_node = gimp_drawable_get_mode_node (GIMP_DRAWABLE (layer));
+
+      mask = gimp_drawable_get_source_node (GIMP_DRAWABLE (layer->mask));
+
+      gegl_node_connect_to (mask,                    "output",
+                            layer->mask_offset_node, "input");
+
+      if (layer->show_mask)
+        {
+          gegl_node_connect_to (layer->mask_offset_node, "output",
+                                mode_node,               "aux");
+        }
+      else
+        {
+          gegl_node_connect_to (layer->mask_offset_node, "output",
+                                mode_node,               "aux2");
+        }
+
+      gimp_layer_update_mode_node (layer);
+    }
+
+  gimp_drawable_update_bounding_box (GIMP_DRAWABLE (layer));
+
+  gimp_layer_update_effective_mode (layer);
+  gimp_layer_update_excludes_backdrop (layer);
+
+  if (gimp_layer_get_apply_mask (layer) ||
+      gimp_layer_get_show_mask (layer))
+    {
+      gimp_drawable_update (GIMP_DRAWABLE (layer), 0, 0, -1, -1);
+    }
+
+  g_signal_connect (mask, "update",
+                    G_CALLBACK (gimp_layer_layer_mask_update),
+                    layer);
+
+  g_signal_emit (layer, layer_signals[MASK_CHANGED], 0);
+
+  g_object_notify (G_OBJECT (layer), "mask");
+
+  /*  if the mask came from the undo stack, reset its "removed" state  */
+  if (gimp_item_is_removed (GIMP_ITEM (mask)))
+    gimp_item_unset_removed (GIMP_ITEM (mask));
+
+  return layer->mask;
+}
+
+GimpLayerMask *
+gimp_layer_create_mask (GimpLayer       *layer,
+                        GimpAddMaskType  add_mask_type,
+                        GimpChannel     *channel)
+{
+  GimpDrawable  *drawable;
+  GimpItem      *item;
+  GimpLayerMask *mask;
+  GimpImage     *image;
+  gchar         *mask_name;
+  GimpRGB        black = { 0.0, 0.0, 0.0, GIMP_OPACITY_OPAQUE };
+
+  g_return_val_if_fail (GIMP_IS_LAYER (layer), NULL);
+  g_return_val_if_fail (add_mask_type != GIMP_ADD_MASK_CHANNEL ||
+                        GIMP_IS_CHANNEL (channel), NULL);
+
+  drawable = GIMP_DRAWABLE (layer);
+  item     = GIMP_ITEM (layer);
+  image    = gimp_item_get_image (item);
+
+  mask_name = g_strdup_printf (_("%s mask"),
+                               gimp_object_get_name (layer));
+
+  mask = gimp_layer_mask_new (image,
+                              gimp_item_get_width  (item),
+                              gimp_item_get_height (item),
+                              mask_name, &black);
+
+  g_free (mask_name);
+
+  switch (add_mask_type)
+    {
+    case GIMP_ADD_MASK_WHITE:
+      gimp_channel_all (GIMP_CHANNEL (mask), FALSE);
+      break;
+
+    case GIMP_ADD_MASK_BLACK:
+      gimp_channel_clear (GIMP_CHANNEL (mask), NULL, FALSE);
+      break;
+
+    case GIMP_ADD_MASK_ALPHA:
+    case GIMP_ADD_MASK_ALPHA_TRANSFER:
+      if (gimp_drawable_has_alpha (drawable))
+        {
+          GeglBuffer *dest_buffer;
+          const Babl *component_format;
+
+          dest_buffer = gimp_drawable_get_buffer (GIMP_DRAWABLE (mask));
+
+          component_format =
+            gimp_image_get_component_format (image, GIMP_CHANNEL_ALPHA);
+
+          gegl_buffer_set_format (dest_buffer, component_format);
+          gimp_gegl_buffer_copy (gimp_drawable_get_buffer (drawable), NULL,
+                                 GEGL_ABYSS_NONE,
+                                 dest_buffer, NULL);
+          gegl_buffer_set_format (dest_buffer, NULL);
+
+          if (add_mask_type == GIMP_ADD_MASK_ALPHA_TRANSFER)
+            {
+              gimp_drawable_push_undo (drawable,
+                                       C_("undo-type", "Transfer Alpha to Mask"),
+                                       NULL,
+                                       0, 0,
+                                       gimp_item_get_width  (item),
+                                       gimp_item_get_height (item));
+
+              gimp_gegl_apply_set_alpha (gimp_drawable_get_buffer (drawable),
+                                         NULL, NULL,
+                                         gimp_drawable_get_buffer (drawable),
+                                         1.0);
+            }
+        }
+      break;
+
+    case GIMP_ADD_MASK_SELECTION:
+    case GIMP_ADD_MASK_CHANNEL:
+      {
+        gboolean channel_empty;
+        gint     offset_x, offset_y;
+        gint     copy_x, copy_y;
+        gint     copy_width, copy_height;
+
+        if (add_mask_type == GIMP_ADD_MASK_SELECTION)
+          channel = GIMP_CHANNEL (gimp_image_get_mask (image));
+
+        channel_empty = gimp_channel_is_empty (channel);
+
+        gimp_item_get_offset (item, &offset_x, &offset_y);
+
+        gimp_rectangle_intersect (0, 0,
+                                  gimp_image_get_width  (image),
+                                  gimp_image_get_height (image),
+                                  offset_x, offset_y,
+                                  gimp_item_get_width  (item),
+                                  gimp_item_get_height (item),
+                                  &copy_x, &copy_y,
+                                  &copy_width, &copy_height);
+
+        if (copy_width  < gimp_item_get_width  (item) ||
+            copy_height < gimp_item_get_height (item) ||
+            channel_empty)
+          gimp_channel_clear (GIMP_CHANNEL (mask), NULL, FALSE);
+
+        if ((copy_width || copy_height) && ! channel_empty)
+          {
+            GeglBuffer *src;
+            GeglBuffer *dest;
+            const Babl *format;
+
+            src  = gimp_drawable_get_buffer (GIMP_DRAWABLE (channel));
+            dest = gimp_drawable_get_buffer (GIMP_DRAWABLE (mask));
+
+            format = gegl_buffer_get_format (src);
+
+            /* make sure no gamma conversion happens */
+            gegl_buffer_set_format (dest, format);
+            gimp_gegl_buffer_copy (src,
+                                   GEGL_RECTANGLE (copy_x, copy_y,
+                                                   copy_width, copy_height),
+                                   GEGL_ABYSS_NONE,
+                                   dest,
+                                   GEGL_RECTANGLE (copy_x - offset_x,
+                                                   copy_y - offset_y,
+                                                   0, 0));
+            gegl_buffer_set_format (dest, NULL);
+
+            GIMP_CHANNEL (mask)->bounds_known = FALSE;
+          }
+      }
+      break;
+
+    case GIMP_ADD_MASK_COPY:
+      {
+        GeglBuffer *src_buffer;
+        GeglBuffer *dest_buffer;
+
+        if (! gimp_drawable_is_gray (drawable))
+          {
+            const Babl *copy_format =
+              gimp_image_get_format (image, GIMP_GRAY,
+                                     gimp_drawable_get_precision (drawable),
+                                     gimp_drawable_has_alpha (drawable));
+
+            src_buffer =
+              gegl_buffer_new (GEGL_RECTANGLE (0, 0,
+                                               gimp_item_get_width  (item),
+                                               gimp_item_get_height (item)),
+                               copy_format);
+
+            gimp_gegl_buffer_copy (gimp_drawable_get_buffer (drawable), NULL,
+                                   GEGL_ABYSS_NONE,
+                                   src_buffer, NULL);
+          }
+        else
+          {
+            src_buffer = gimp_drawable_get_buffer (drawable);
+            g_object_ref (src_buffer);
+          }
+
+        dest_buffer = gimp_drawable_get_buffer (GIMP_DRAWABLE (mask));
+
+        if (gimp_drawable_has_alpha (drawable))
+          {
+            GimpRGB background;
+
+            gimp_rgba_set (&background, 0.0, 0.0, 0.0, 0.0);
+
+            gimp_gegl_apply_flatten (src_buffer, NULL, NULL,
+                                     dest_buffer, &background,
+                                     GIMP_LAYER_COLOR_SPACE_RGB_LINEAR);
+          }
+        else
+          {
+            gimp_gegl_buffer_copy (src_buffer, NULL, GEGL_ABYSS_NONE,
+                                   dest_buffer, NULL);
+          }
+
+        g_object_unref (src_buffer);
+      }
+
+      GIMP_CHANNEL (mask)->bounds_known = FALSE;
+      break;
+    }
+
+  return mask;
+}
+
+void
+gimp_layer_apply_mask (GimpLayer         *layer,
+                       GimpMaskApplyMode  mode,
+                       gboolean           push_undo)
+{
+  GimpItem      *item;
+  GimpImage     *image;
+  GimpLayerMask *mask;
+  gboolean       view_changed = FALSE;
+
+  g_return_if_fail (GIMP_IS_LAYER (layer));
+
+  mask = gimp_layer_get_mask (layer);
+
+  if (! mask)
+    return;
+
+  /*  APPLY can not be done to group layers  */
+  g_return_if_fail (! gimp_viewable_get_children (GIMP_VIEWABLE (layer)) ||
+                    mode == GIMP_MASK_DISCARD);
+
+  /*  APPLY can only be done to layers with an alpha channel  */
+  g_return_if_fail (gimp_drawable_has_alpha (GIMP_DRAWABLE (layer)) ||
+                    mode == GIMP_MASK_DISCARD || push_undo == TRUE);
+
+  item  = GIMP_ITEM (layer);
+  image = gimp_item_get_image (item);
+
+  if (! image)
+    return;
+
+  if (push_undo)
+    {
+      gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_LAYER_APPLY_MASK,
+                                   (mode == GIMP_MASK_APPLY) ?
+                                   C_("undo-type", "Apply Layer Mask") :
+                                   C_("undo-type", "Delete Layer Mask"));
+
+      gimp_image_undo_push_layer_mask_show (image, NULL, layer);
+      gimp_image_undo_push_layer_mask_apply (image, NULL, layer);
+      gimp_image_undo_push_layer_mask_remove (image, NULL, layer, mask);
+
+      if (mode == GIMP_MASK_APPLY &&
+          ! gimp_drawable_has_alpha (GIMP_DRAWABLE (layer)))
+        {
+          gimp_layer_add_alpha (layer);
+        }
+    }
+
+  /*  check if applying the mask changes the projection  */
+  if (gimp_layer_get_show_mask (layer)                                   ||
+      (mode == GIMP_MASK_APPLY   && ! gimp_layer_get_apply_mask (layer)) ||
+      (mode == GIMP_MASK_DISCARD &&   gimp_layer_get_apply_mask (layer)))
+    {
+      view_changed = TRUE;
+    }
+
+  if (mode == GIMP_MASK_APPLY)
+    {
+      GeglBuffer *mask_buffer;
+      GeglBuffer *dest_buffer;
+
+      if (push_undo)
+        gimp_drawable_push_undo (GIMP_DRAWABLE (layer), NULL,
+                                 NULL,
+                                 0, 0,
+                                 gimp_item_get_width  (item),
+                                 gimp_item_get_height (item));
+
+      /*  Combine the current layer's alpha channel and the mask  */
+      mask_buffer = gimp_drawable_get_buffer (GIMP_DRAWABLE (mask));
+      dest_buffer = gimp_drawable_get_buffer (GIMP_DRAWABLE (layer));
+
+      gimp_gegl_apply_opacity (gimp_drawable_get_buffer (GIMP_DRAWABLE (layer)),
+                               NULL, NULL, dest_buffer,
+                               mask_buffer, 0, 0, 1.0);
+    }
+
+  g_signal_handlers_disconnect_by_func (mask,
+                                        gimp_layer_layer_mask_update,
+                                        layer);
+
+  gimp_item_removed (GIMP_ITEM (mask));
+  g_object_unref (mask);
+  layer->mask = NULL;
+
+  if (push_undo)
+    gimp_image_undo_group_end (image);
+
+  if (gimp_filter_peek_node (GIMP_FILTER (layer)))
+    {
+      GeglNode *mode_node;
+
+      mode_node = gimp_drawable_get_mode_node (GIMP_DRAWABLE (layer));
+
+      if (layer->show_mask)
+        {
+          gegl_node_connect_to (layer->layer_offset_node, "output",
+                                mode_node,                "aux");
+        }
+      else
+        {
+          gegl_node_disconnect (mode_node, "aux2");
+        }
+
+      gimp_layer_update_mode_node (layer);
+    }
+
+  gimp_drawable_update_bounding_box (GIMP_DRAWABLE (layer));
+
+  gimp_layer_update_effective_mode (layer);
+  gimp_layer_update_excludes_backdrop (layer);
+
+  /*  If applying actually changed the view  */
+  if (view_changed)
+    {
+      gimp_drawable_update (GIMP_DRAWABLE (layer), 0, 0, -1, -1);
+    }
+  else
+    {
+      gimp_viewable_invalidate_preview (GIMP_VIEWABLE (layer));
+    }
+
+  g_signal_emit (layer, layer_signals[MASK_CHANGED], 0);
+
+  g_object_notify (G_OBJECT (layer), "mask");
+}
+
+void
+gimp_layer_set_apply_mask (GimpLayer *layer,
+                           gboolean   apply,
+                           gboolean   push_undo)
+{
+  g_return_if_fail (GIMP_IS_LAYER (layer));
+  g_return_if_fail (layer->mask != NULL);
+
+  if (layer->apply_mask != apply)
+    {
+      GimpImage *image = gimp_item_get_image (GIMP_ITEM (layer));
+
+      if (push_undo && gimp_item_is_attached (GIMP_ITEM (layer)))
+        gimp_image_undo_push_layer_mask_apply (image,
+                                               apply ?
+                                               C_("undo-type", "Enable Layer Mask") :
+                                               C_("undo-type", "Disable Layer Mask"),
+                                               layer);
+
+      layer->apply_mask = apply ? TRUE : FALSE;
+
+      if (gimp_filter_peek_node (GIMP_FILTER (layer)) &&
+          ! gimp_layer_get_show_mask (layer))
+        {
+          GeglNode *mode_node;
+
+          mode_node = gimp_drawable_get_mode_node (GIMP_DRAWABLE (layer));
+
+          if (layer->apply_mask)
+            {
+              gegl_node_connect_to (layer->mask_offset_node, "output",
+                                    mode_node,               "aux2");
+            }
+          else
+            {
+              gegl_node_disconnect (mode_node, "aux2");
+            }
+        }
+
+      gimp_drawable_update_bounding_box (GIMP_DRAWABLE (layer));
+
+      gimp_layer_update_effective_mode (layer);
+      gimp_layer_update_excludes_backdrop (layer);
+
+      gimp_drawable_update (GIMP_DRAWABLE (layer), 0, 0, -1, -1);
+
+      g_signal_emit (layer, layer_signals[APPLY_MASK_CHANGED], 0);
+    }
+}
+
+gboolean
+gimp_layer_get_apply_mask (GimpLayer *layer)
+{
+  g_return_val_if_fail (GIMP_IS_LAYER (layer), FALSE);
+  g_return_val_if_fail (layer->mask, FALSE);
+
+  return layer->apply_mask;
+}
+
+void
+gimp_layer_set_edit_mask (GimpLayer *layer,
+                          gboolean   edit)
+{
+  g_return_if_fail (GIMP_IS_LAYER (layer));
+  g_return_if_fail (layer->mask != NULL);
+
+  if (layer->edit_mask != edit)
+    {
+      layer->edit_mask = edit ? TRUE : FALSE;
+
+      g_signal_emit (layer, layer_signals[EDIT_MASK_CHANGED], 0);
+    }
+}
+
+gboolean
+gimp_layer_get_edit_mask (GimpLayer *layer)
+{
+  g_return_val_if_fail (GIMP_IS_LAYER (layer), FALSE);
+  g_return_val_if_fail (layer->mask, FALSE);
+
+  return layer->edit_mask;
+}
+
+void
+gimp_layer_set_show_mask (GimpLayer *layer,
+                          gboolean   show,
+                          gboolean   push_undo)
+{
+  g_return_if_fail (GIMP_IS_LAYER (layer));
+  g_return_if_fail (layer->mask != NULL);
+
+  if (layer->show_mask != show)
+    {
+      GimpImage *image = gimp_item_get_image (GIMP_ITEM (layer));
+
+      if (push_undo)
+        gimp_image_undo_push_layer_mask_show (image,
+                                              C_("undo-type", "Show Layer Mask"),
+                                              layer);
+
+      layer->show_mask = show ? TRUE : FALSE;
+
+      if (gimp_filter_peek_node (GIMP_FILTER (layer)))
+        {
+          GeglNode *mode_node;
+
+          mode_node = gimp_drawable_get_mode_node (GIMP_DRAWABLE (layer));
+
+          if (layer->show_mask)
+            {
+              gegl_node_disconnect (mode_node, "aux2");
+
+              gegl_node_connect_to (layer->mask_offset_node, "output",
+                                    mode_node,               "aux");
+            }
+          else
+            {
+              gegl_node_connect_to (layer->layer_offset_node, "output",
+                                    mode_node,                "aux");
+
+              if (gimp_layer_get_apply_mask (layer))
+                {
+                  gegl_node_connect_to (layer->mask_offset_node, "output",
+                                        mode_node,               "aux2");
+                }
+            }
+
+          gimp_layer_update_mode_node (layer);
+        }
+
+      gimp_drawable_update_bounding_box (GIMP_DRAWABLE (layer));
+
+      gimp_layer_update_effective_mode (layer);
+      gimp_layer_update_excludes_backdrop (layer);
+
+      gimp_drawable_update (GIMP_DRAWABLE (layer), 0, 0, -1, -1);
+
+      g_signal_emit (layer, layer_signals[SHOW_MASK_CHANGED], 0);
+    }
+}
+
+gboolean
+gimp_layer_get_show_mask (GimpLayer *layer)
+{
+  g_return_val_if_fail (GIMP_IS_LAYER (layer), FALSE);
+  g_return_val_if_fail (layer->mask, FALSE);
+
+  return layer->show_mask;
+}
+
+void
+gimp_layer_add_alpha (GimpLayer *layer)
+{
+  GimpItem     *item;
+  GimpDrawable *drawable;
+  GeglBuffer   *new_buffer;
+
+  g_return_if_fail (GIMP_IS_LAYER (layer));
+
+  if (gimp_drawable_has_alpha (GIMP_DRAWABLE (layer)))
+    return;
+
+  item     = GIMP_ITEM (layer);
+  drawable = GIMP_DRAWABLE (layer);
+
+  new_buffer = gegl_buffer_new (GEGL_RECTANGLE (0, 0,
+                                                gimp_item_get_width  (item),
+                                                gimp_item_get_height (item)),
+                                gimp_drawable_get_format_with_alpha (drawable));
+
+  gimp_gegl_buffer_copy (
+    gimp_drawable_get_buffer (drawable), NULL, GEGL_ABYSS_NONE,
+    new_buffer, NULL);
+
+  gimp_drawable_set_buffer (GIMP_DRAWABLE (layer),
+                            gimp_item_is_attached (GIMP_ITEM (layer)),
+                            C_("undo-type", "Add Alpha Channel"),
+                            new_buffer);
+  g_object_unref (new_buffer);
+}
+
+void
+gimp_layer_remove_alpha (GimpLayer   *layer,
+                         GimpContext *context)
+{
+  GeglBuffer *new_buffer;
+  GimpRGB     background;
+
+  g_return_if_fail (GIMP_IS_LAYER (layer));
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  if (! gimp_drawable_has_alpha (GIMP_DRAWABLE (layer)))
+    return;
+
+  new_buffer =
+    gegl_buffer_new (GEGL_RECTANGLE (0, 0,
+                                     gimp_item_get_width  (GIMP_ITEM (layer)),
+                                     gimp_item_get_height (GIMP_ITEM (layer))),
+                     gimp_drawable_get_format_without_alpha (GIMP_DRAWABLE (layer)));
+
+  gimp_context_get_background (context, &background);
+  gimp_pickable_srgb_to_image_color (GIMP_PICKABLE (layer),
+                                     &background, &background);
+
+  gimp_gegl_apply_flatten (gimp_drawable_get_buffer (GIMP_DRAWABLE (layer)),
+                           NULL, NULL,
+                           new_buffer, &background,
+                           gimp_layer_get_real_composite_space (layer));
+
+  gimp_drawable_set_buffer (GIMP_DRAWABLE (layer),
+                            gimp_item_is_attached (GIMP_ITEM (layer)),
+                            C_("undo-type", "Remove Alpha Channel"),
+                            new_buffer);
+  g_object_unref (new_buffer);
+}
+
+void
+gimp_layer_resize_to_image (GimpLayer    *layer,
+                            GimpContext  *context,
+                            GimpFillType  fill_type)
+{
+  GimpImage *image;
+  gint       offset_x;
+  gint       offset_y;
+
+  g_return_if_fail (GIMP_IS_LAYER (layer));
+  g_return_if_fail (gimp_item_is_attached (GIMP_ITEM (layer)));
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+
+  image = gimp_item_get_image (GIMP_ITEM (layer));
+
+  gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_ITEM_RESIZE,
+                               C_("undo-type", "Layer to Image Size"));
+
+  gimp_item_get_offset (GIMP_ITEM (layer), &offset_x, &offset_y);
+  gimp_item_resize (GIMP_ITEM (layer), context, fill_type,
+                    gimp_image_get_width  (image),
+                    gimp_image_get_height (image),
+                    offset_x, offset_y);
+
+  gimp_image_undo_group_end (image);
+}
+
+/**********************/
+/*  access functions  */
+/**********************/
+
+GimpDrawable *
+gimp_layer_get_floating_sel_drawable (GimpLayer *layer)
+{
+  g_return_val_if_fail (GIMP_IS_LAYER (layer), NULL);
+
+  return layer->fs.drawable;
+}
+
+void
+gimp_layer_set_floating_sel_drawable (GimpLayer    *layer,
+                                      GimpDrawable *drawable)
+{
+  g_return_if_fail (GIMP_IS_LAYER (layer));
+  g_return_if_fail (drawable == NULL || GIMP_IS_DRAWABLE (drawable));
+
+  if (g_set_object (&layer->fs.drawable, drawable))
+    {
+      if (layer->fs.segs)
+        {
+          g_clear_pointer (&layer->fs.segs, g_free);
+          layer->fs.num_segs = 0;
+        }
+
+      g_object_notify (G_OBJECT (layer), "floating-selection");
+    }
+}
+
+gboolean
+gimp_layer_is_floating_sel (GimpLayer *layer)
+{
+  g_return_val_if_fail (GIMP_IS_LAYER (layer), FALSE);
+
+  return (gimp_layer_get_floating_sel_drawable (layer) != NULL);
+}
+
+void
+gimp_layer_set_opacity (GimpLayer *layer,
+                        gdouble    opacity,
+                        gboolean   push_undo)
+{
+  g_return_if_fail (GIMP_IS_LAYER (layer));
+
+  opacity = CLAMP (opacity, GIMP_OPACITY_TRANSPARENT, GIMP_OPACITY_OPAQUE);
+
+  if (layer->opacity != opacity)
+    {
+      if (push_undo && gimp_item_is_attached (GIMP_ITEM (layer)))
+        {
+          GimpImage *image = gimp_item_get_image (GIMP_ITEM (layer));
+
+          gimp_image_undo_push_layer_opacity (image, NULL, layer);
+        }
+
+      layer->opacity = opacity;
+
+      g_signal_emit (layer, layer_signals[OPACITY_CHANGED], 0);
+      g_object_notify (G_OBJECT (layer), "opacity");
+
+      if (gimp_filter_peek_node (GIMP_FILTER (layer)))
+        gimp_layer_update_mode_node (layer);
+
+      gimp_drawable_update (GIMP_DRAWABLE (layer), 0, 0, -1, -1);
+    }
+}
+
+gdouble
+gimp_layer_get_opacity (GimpLayer *layer)
+{
+  g_return_val_if_fail (GIMP_IS_LAYER (layer), GIMP_OPACITY_OPAQUE);
+
+  return layer->opacity;
+}
+
+void
+gimp_layer_set_mode (GimpLayer     *layer,
+                     GimpLayerMode  mode,
+                     gboolean       push_undo)
+{
+  g_return_if_fail (GIMP_IS_LAYER (layer));
+
+  if (gimp_viewable_get_children (GIMP_VIEWABLE (layer)) == NULL)
+    {
+      g_return_if_fail (gimp_layer_mode_get_context (mode) &
+                        GIMP_LAYER_MODE_CONTEXT_LAYER);
+    }
+  else
+    {
+      g_return_if_fail (gimp_layer_mode_get_context (mode) &
+                        GIMP_LAYER_MODE_CONTEXT_GROUP);
+    }
+
+  if (layer->mode != mode)
+    {
+      if (gimp_item_is_attached (GIMP_ITEM (layer)))
+        {
+          GimpImage *image = gimp_item_get_image (GIMP_ITEM (layer));
+
+          gimp_image_unset_default_new_layer_mode (image);
+
+          if (push_undo)
+            gimp_image_undo_push_layer_mode (image, NULL, layer);
+        }
+
+      g_object_freeze_notify (G_OBJECT (layer));
+
+      layer->mode = mode;
+
+      g_signal_emit (layer, layer_signals[MODE_CHANGED], 0);
+      g_object_notify (G_OBJECT (layer), "mode");
+
+      /*  when changing modes, we always switch to AUTO blend and
+       *  composite in order to avoid confusion
+       */
+      if (layer->blend_space != GIMP_LAYER_COLOR_SPACE_AUTO)
+        {
+          layer->blend_space = GIMP_LAYER_COLOR_SPACE_AUTO;
+
+          g_signal_emit (layer, layer_signals[BLEND_SPACE_CHANGED], 0);
+          g_object_notify (G_OBJECT (layer), "blend-space");
+        }
+
+      if (layer->composite_space != GIMP_LAYER_COLOR_SPACE_AUTO)
+        {
+          layer->composite_space = GIMP_LAYER_COLOR_SPACE_AUTO;
+
+          g_signal_emit (layer, layer_signals[COMPOSITE_SPACE_CHANGED], 0);
+          g_object_notify (G_OBJECT (layer), "composite-space");
+        }
+
+      if (layer->composite_mode != GIMP_LAYER_COMPOSITE_AUTO)
+        {
+          layer->composite_mode = GIMP_LAYER_COMPOSITE_AUTO;
+
+          g_signal_emit (layer, layer_signals[COMPOSITE_MODE_CHANGED], 0);
+          g_object_notify (G_OBJECT (layer), "composite-mode");
+        }
+
+      g_object_thaw_notify (G_OBJECT (layer));
+
+      gimp_layer_update_effective_mode (layer);
+      gimp_layer_update_excludes_backdrop (layer);
+    }
+}
+
+GimpLayerMode
+gimp_layer_get_mode (GimpLayer *layer)
+{
+  g_return_val_if_fail (GIMP_IS_LAYER (layer), GIMP_LAYER_MODE_NORMAL);
+
+  return layer->mode;
+}
+
+void
+gimp_layer_set_blend_space (GimpLayer           *layer,
+                            GimpLayerColorSpace  blend_space,
+                            gboolean             push_undo)
+{
+  g_return_if_fail (GIMP_IS_LAYER (layer));
+
+  if (! gimp_layer_mode_is_blend_space_mutable (layer->mode))
+    return;
+
+  if (layer->blend_space != blend_space)
+    {
+      if (push_undo && gimp_item_is_attached (GIMP_ITEM (layer)))
+        {
+          GimpImage *image = gimp_item_get_image (GIMP_ITEM (layer));
+
+          gimp_image_undo_push_layer_mode (image, NULL, layer);
+        }
+
+      layer->blend_space = blend_space;
+
+      g_signal_emit (layer, layer_signals[BLEND_SPACE_CHANGED], 0);
+      g_object_notify (G_OBJECT (layer), "blend-space");
+
+      gimp_layer_update_effective_mode (layer);
+    }
+}
+
+GimpLayerColorSpace
+gimp_layer_get_blend_space (GimpLayer *layer)
+{
+  g_return_val_if_fail (GIMP_IS_LAYER (layer), GIMP_LAYER_COLOR_SPACE_AUTO);
+
+  return layer->blend_space;
+}
+
+GimpLayerColorSpace
+gimp_layer_get_real_blend_space (GimpLayer *layer)
+{
+  g_return_val_if_fail (GIMP_IS_LAYER (layer), GIMP_LAYER_COLOR_SPACE_RGB_LINEAR);
+
+  if (layer->blend_space == GIMP_LAYER_COLOR_SPACE_AUTO)
+    return gimp_layer_mode_get_blend_space (layer->mode);
+  else
+    return layer->blend_space;
+}
+
+void
+gimp_layer_set_composite_space (GimpLayer           *layer,
+                                GimpLayerColorSpace  composite_space,
+                                gboolean             push_undo)
+{
+  g_return_if_fail (GIMP_IS_LAYER (layer));
+
+  if (! gimp_layer_mode_is_composite_space_mutable (layer->mode))
+    return;
+
+  if (layer->composite_space != composite_space)
+    {
+      if (push_undo && gimp_item_is_attached (GIMP_ITEM (layer)))
+        {
+          GimpImage *image = gimp_item_get_image (GIMP_ITEM (layer));
+
+          gimp_image_undo_push_layer_mode (image, NULL, layer);
+        }
+
+      layer->composite_space = composite_space;
+
+      g_signal_emit (layer, layer_signals[COMPOSITE_SPACE_CHANGED], 0);
+      g_object_notify (G_OBJECT (layer), "composite-space");
+
+      gimp_layer_update_effective_mode (layer);
+    }
+}
+
+GimpLayerColorSpace
+gimp_layer_get_composite_space (GimpLayer *layer)
+{
+  g_return_val_if_fail (GIMP_IS_LAYER (layer), GIMP_LAYER_COLOR_SPACE_AUTO);
+
+  return layer->composite_space;
+}
+
+GimpLayerColorSpace
+gimp_layer_get_real_composite_space (GimpLayer *layer)
+{
+  g_return_val_if_fail (GIMP_IS_LAYER (layer), GIMP_LAYER_COLOR_SPACE_RGB_LINEAR);
+
+  if (layer->composite_space == GIMP_LAYER_COLOR_SPACE_AUTO)
+    return gimp_layer_mode_get_composite_space (layer->mode);
+  else
+    return layer->composite_space;
+}
+
+void
+gimp_layer_set_composite_mode (GimpLayer              *layer,
+                               GimpLayerCompositeMode  composite_mode,
+                               gboolean                push_undo)
+{
+  g_return_if_fail (GIMP_IS_LAYER (layer));
+
+  if (! gimp_layer_mode_is_composite_mode_mutable (layer->mode))
+    return;
+
+  if (layer->composite_mode != composite_mode)
+    {
+      if (push_undo && gimp_item_is_attached (GIMP_ITEM (layer)))
+        {
+          GimpImage *image = gimp_item_get_image (GIMP_ITEM (layer));
+
+          gimp_image_undo_push_layer_mode (image, NULL, layer);
+        }
+
+      layer->composite_mode = composite_mode;
+
+      g_signal_emit (layer, layer_signals[COMPOSITE_MODE_CHANGED], 0);
+      g_object_notify (G_OBJECT (layer), "composite-mode");
+
+      gimp_layer_update_effective_mode (layer);
+      gimp_layer_update_excludes_backdrop (layer);
+    }
+}
+
+GimpLayerCompositeMode
+gimp_layer_get_composite_mode (GimpLayer *layer)
+{
+  g_return_val_if_fail (GIMP_IS_LAYER (layer), GIMP_LAYER_COMPOSITE_AUTO);
+
+  return layer->composite_mode;
+}
+
+GimpLayerCompositeMode
+gimp_layer_get_real_composite_mode (GimpLayer *layer)
+{
+  g_return_val_if_fail (GIMP_IS_LAYER (layer), GIMP_LAYER_COMPOSITE_UNION);
+
+  if (layer->composite_mode == GIMP_LAYER_COMPOSITE_AUTO)
+    return gimp_layer_mode_get_composite_mode (layer->mode);
+  else
+    return layer->composite_mode;
+}
+
+void
+gimp_layer_get_effective_mode (GimpLayer              *layer,
+                               GimpLayerMode          *mode,
+                               GimpLayerColorSpace    *blend_space,
+                               GimpLayerColorSpace    *composite_space,
+                               GimpLayerCompositeMode *composite_mode)
+{
+  g_return_if_fail (GIMP_IS_LAYER (layer));
+
+  if (mode)            *mode            = layer->effective_mode;
+  if (blend_space)     *blend_space     = layer->effective_blend_space;
+  if (composite_space) *composite_space = layer->effective_composite_space;
+  if (composite_mode)  *composite_mode  = layer->effective_composite_mode;
+}
+
+gboolean
+gimp_layer_get_excludes_backdrop (GimpLayer *layer)
+{
+  g_return_val_if_fail (GIMP_IS_LAYER (layer), FALSE);
+
+  return layer->excludes_backdrop;
+}
+
+void
+gimp_layer_set_lock_alpha (GimpLayer *layer,
+                           gboolean   lock_alpha,
+                           gboolean   push_undo)
+{
+  g_return_if_fail (GIMP_IS_LAYER (layer));
+  g_return_if_fail (gimp_layer_can_lock_alpha (layer));
+
+  lock_alpha = lock_alpha ? TRUE : FALSE;
+
+  if (layer->lock_alpha != lock_alpha)
+    {
+      if (push_undo && gimp_item_is_attached (GIMP_ITEM (layer)))
+        {
+          GimpImage *image = gimp_item_get_image (GIMP_ITEM (layer));
+
+          gimp_image_undo_push_layer_lock_alpha (image, NULL, layer);
+        }
+
+      layer->lock_alpha = lock_alpha;
+
+      g_signal_emit (layer, layer_signals[LOCK_ALPHA_CHANGED], 0);
+      g_object_notify (G_OBJECT (layer), "lock-alpha");
+    }
+}
+
+gboolean
+gimp_layer_get_lock_alpha (GimpLayer *layer)
+{
+  g_return_val_if_fail (GIMP_IS_LAYER (layer), FALSE);
+
+  return layer->lock_alpha;
+}
+
+gboolean
+gimp_layer_can_lock_alpha (GimpLayer *layer)
+{
+  g_return_val_if_fail (GIMP_IS_LAYER (layer), FALSE);
+
+  if (gimp_viewable_get_children (GIMP_VIEWABLE (layer)))
+    return FALSE;
+
+  return TRUE;
+}
+
+
+/*  protected functions  */
+
+void
+gimp_layer_update_effective_mode (GimpLayer *layer)
+{
+  GimpLayerMode          mode;
+  GimpLayerColorSpace    blend_space;
+  GimpLayerColorSpace    composite_space;
+  GimpLayerCompositeMode composite_mode;
+
+  g_return_if_fail (GIMP_IS_LAYER (layer));
+
+  if (layer->mask && layer->show_mask)
+    {
+      mode            = GIMP_LAYER_MODE_NORMAL;
+      blend_space     = GIMP_LAYER_COLOR_SPACE_AUTO;
+      composite_space = GIMP_LAYER_COLOR_SPACE_AUTO;
+      composite_mode  = GIMP_LAYER_COMPOSITE_AUTO;
+
+      /* This makes sure that masks of LEGACY-mode layers are
+       * composited in PERCEPTUAL space, and non-LEGACY layers in
+       * LINEAR space, or whatever composite space was chosen in the
+       * layer attributes dialog
+       */
+      composite_space = gimp_layer_get_real_composite_space (layer);
+    }
+  else
+    {
+      GIMP_LAYER_GET_CLASS (layer)->get_effective_mode (layer,
+                                                        &mode,
+                                                        &blend_space,
+                                                        &composite_space,
+                                                        &composite_mode);
+    }
+
+  if (mode            != layer->effective_mode            ||
+      blend_space     != layer->effective_blend_space     ||
+      composite_space != layer->effective_composite_space ||
+      composite_mode  != layer->effective_composite_mode)
+    {
+      layer->effective_mode            = mode;
+      layer->effective_blend_space     = blend_space;
+      layer->effective_composite_space = composite_space;
+      layer->effective_composite_mode  = composite_mode;
+
+      g_signal_emit (layer, layer_signals[EFFECTIVE_MODE_CHANGED], 0);
+
+      if (gimp_filter_peek_node (GIMP_FILTER (layer)))
+        gimp_layer_update_mode_node (layer);
+
+      gimp_drawable_update (GIMP_DRAWABLE (layer), 0, 0, -1, -1);
+    }
+}
+
+void
+gimp_layer_update_excludes_backdrop (GimpLayer *layer)
+{
+  gboolean excludes_backdrop;
+
+  g_return_if_fail (GIMP_IS_LAYER (layer));
+
+  excludes_backdrop =
+    GIMP_LAYER_GET_CLASS (layer)->get_excludes_backdrop (layer);
+
+  if (excludes_backdrop != layer->excludes_backdrop)
+    {
+      layer->excludes_backdrop = excludes_backdrop;
+
+      g_signal_emit (layer, layer_signals[EXCLUDES_BACKDROP_CHANGED], 0);
+      g_object_notify (G_OBJECT (layer), "excludes-backdrop");
+    }
+}
diff --git a/app/core/gimplayer.h b/app/core/gimplayer.h
new file mode 100644
index 0000000..f8c9d82
--- /dev/null
+++ b/app/core/gimplayer.h
@@ -0,0 +1,243 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_LAYER_H__
+#define __GIMP_LAYER_H__
+
+
+#include "gimpdrawable.h"
+
+
+#define GIMP_TYPE_LAYER            (gimp_layer_get_type ())
+#define GIMP_LAYER(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_LAYER, GimpLayer))
+#define GIMP_LAYER_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_LAYER, GimpLayerClass))
+#define GIMP_IS_LAYER(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_LAYER))
+#define GIMP_IS_LAYER_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_LAYER))
+#define GIMP_LAYER_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_LAYER, GimpLayerClass))
+
+
+typedef struct _GimpLayerClass GimpLayerClass;
+
+struct _GimpLayer
+{
+  GimpDrawable            parent_instance;
+
+  gdouble                 opacity;                    /*  layer opacity                     */
+  GimpLayerMode           mode;                       /*  layer combination mode            */
+  GimpLayerColorSpace     blend_space;                /*  layer blend space                 */
+  GimpLayerColorSpace     composite_space;            /*  layer composite space             */
+  GimpLayerCompositeMode  composite_mode;             /*  layer composite mode              */
+  GimpLayerMode           effective_mode;             /*  layer effective combination mode  */
+  GimpLayerColorSpace     effective_blend_space;      /*  layer effective blend space       */
+  GimpLayerColorSpace     effective_composite_space;  /*  layer effective composite space   */
+  GimpLayerCompositeMode  effective_composite_mode;   /*  layer effective composite mode    */
+  gboolean                excludes_backdrop;          /*  layer clips backdrop              */
+  gboolean                lock_alpha;                 /*  lock the alpha channel            */
+
+  GimpLayerMask          *mask;                       /*  possible layer mask               */
+  gboolean                apply_mask;                 /*  controls mask application         */
+  gboolean                edit_mask;                  /*  edit mask or layer?               */
+  gboolean                show_mask;                  /*  show mask or layer?               */
+
+  GSList                 *move_stack;                 /*  ancestors affected by move        */
+
+  GeglNode               *layer_offset_node;
+  GeglNode               *mask_offset_node;
+
+  /*  Floating selections  */
+  struct
+  {
+    GimpDrawable *drawable;           /*  floating sel is attached to    */
+    gboolean      boundary_known;     /*  is the current boundary valid  */
+    GimpBoundSeg *segs;               /*  boundary of floating sel       */
+    gint          num_segs;           /*  number of segs in boundary     */
+  } fs;
+};
+
+struct _GimpLayerClass
+{
+  GimpDrawableClass  parent_class;
+
+  /*  signals  */
+  void          (* opacity_changed)           (GimpLayer              *layer);
+  void          (* mode_changed)              (GimpLayer              *layer);
+  void          (* blend_space_changed)       (GimpLayer              *layer);
+  void          (* composite_space_changed)   (GimpLayer              *layer);
+  void          (* composite_mode_changed)    (GimpLayer              *layer);
+  void          (* effective_mode_changed)    (GimpLayer              *layer);
+  void          (* excludes_backdrop_changed) (GimpLayer              *layer);
+  void          (* lock_alpha_changed)        (GimpLayer              *layer);
+  void          (* mask_changed)              (GimpLayer              *layer);
+  void          (* apply_mask_changed)        (GimpLayer              *layer);
+  void          (* edit_mask_changed)         (GimpLayer              *layer);
+  void          (* show_mask_changed)         (GimpLayer              *layer);
+
+  /*  virtual functions  */
+  void          (* translate)                 (GimpLayer              *layer,
+                                               gint                    offset_x,
+                                               gint                    offset_y);
+  void          (* scale)                     (GimpLayer              *layer,
+                                               gint                    new_width,
+                                               gint                    new_height,
+                                               gint                    new_offset_x,
+                                               gint                    new_offset_y,
+                                               GimpInterpolationType   interpolation_type,
+                                               GimpProgress           *progress);
+  void          (* resize)                    (GimpLayer              *layer,
+                                               GimpContext            *context,
+                                               GimpFillType            fill_type,
+                                               gint                    new_width,
+                                               gint                    new_height,
+                                               gint                    offset_x,
+                                               gint                    offset_y);
+  void          (* flip)                      (GimpLayer              *layer,
+                                               GimpContext            *context,
+                                               GimpOrientationType     flip_type,
+                                               gdouble                 axis,
+                                               gboolean                clip_result);
+  void          (* rotate)                    (GimpLayer              *layer,
+                                               GimpContext            *context,
+                                               GimpRotationType        rotate_type,
+                                               gdouble                 center_x,
+                                               gdouble                 center_y,
+                                               gboolean                clip_result);
+  void          (* transform)                 (GimpLayer              *layer,
+                                               GimpContext            *context,
+                                               const GimpMatrix3      *matrix,
+                                               GimpTransformDirection  direction,
+                                               GimpInterpolationType   interpolation_type,
+                                               GimpTransformResize     clip_result,
+                                               GimpProgress           *progress);
+  void          (* convert_type)              (GimpLayer              *layer,
+                                               GimpImage              *dest_image,
+                                               const Babl             *new_format,
+                                               GimpColorProfile       *dest_profile,
+                                               GeglDitherMethod        layer_dither_type,
+                                               GeglDitherMethod        mask_dither_type,
+                                               gboolean                push_undo,
+                                               GimpProgress           *progress);
+  GeglRectangle (* get_bounding_box)          (GimpLayer              *layer);
+  void          (* get_effective_mode)        (GimpLayer              *layer,
+                                               GimpLayerMode          *mode,
+                                               GimpLayerColorSpace    *blend_space,
+                                               GimpLayerColorSpace    *composite_space,
+                                               GimpLayerCompositeMode *composite_mode);
+  gboolean      (* get_excludes_backdrop)     (GimpLayer              *layer);
+};
+
+
+/*  function declarations  */
+
+GType           gimp_layer_get_type            (void) G_GNUC_CONST;
+
+GimpLayer     * gimp_layer_get_parent          (GimpLayer            *layer);
+
+GimpLayerMask * gimp_layer_get_mask            (GimpLayer            *layer);
+GimpLayerMask * gimp_layer_create_mask         (GimpLayer            *layer,
+                                                GimpAddMaskType       mask_type,
+                                                GimpChannel          *channel);
+GimpLayerMask * gimp_layer_add_mask            (GimpLayer            *layer,
+                                                GimpLayerMask        *mask,
+                                                gboolean              push_undo,
+                                                GError              **error);
+void            gimp_layer_apply_mask          (GimpLayer            *layer,
+                                                GimpMaskApplyMode     mode,
+                                                gboolean              push_undo);
+
+void            gimp_layer_set_apply_mask      (GimpLayer           *layer,
+                                                gboolean             apply,
+                                                gboolean             push_undo);
+gboolean        gimp_layer_get_apply_mask      (GimpLayer           *layer);
+
+void            gimp_layer_set_edit_mask       (GimpLayer           *layer,
+                                                gboolean             edit);
+gboolean        gimp_layer_get_edit_mask       (GimpLayer           *layer);
+
+void            gimp_layer_set_show_mask       (GimpLayer           *layer,
+                                                gboolean             show,
+                                                gboolean             push_undo);
+gboolean        gimp_layer_get_show_mask       (GimpLayer           *layer);
+
+void            gimp_layer_add_alpha           (GimpLayer            *layer);
+void            gimp_layer_remove_alpha        (GimpLayer            *layer,
+                                                GimpContext          *context);
+
+void            gimp_layer_resize_to_image     (GimpLayer            *layer,
+                                                GimpContext          *context,
+                                                GimpFillType          fill_type);
+
+GimpDrawable * gimp_layer_get_floating_sel_drawable (GimpLayer       *layer);
+void           gimp_layer_set_floating_sel_drawable (GimpLayer       *layer,
+                                                     GimpDrawable    *drawable);
+gboolean        gimp_layer_is_floating_sel     (GimpLayer            *layer);
+
+void            gimp_layer_set_opacity         (GimpLayer            *layer,
+                                                gdouble               opacity,
+                                                gboolean              push_undo);
+gdouble         gimp_layer_get_opacity         (GimpLayer            *layer);
+
+void            gimp_layer_set_mode            (GimpLayer            *layer,
+                                                GimpLayerMode         mode,
+                                                gboolean              push_undo);
+GimpLayerMode   gimp_layer_get_mode            (GimpLayer            *layer);
+
+void            gimp_layer_set_blend_space     (GimpLayer            *layer,
+                                                GimpLayerColorSpace   blend_space,
+                                                gboolean              push_undo);
+GimpLayerColorSpace
+                gimp_layer_get_blend_space     (GimpLayer            *layer);
+GimpLayerColorSpace
+               gimp_layer_get_real_blend_space (GimpLayer            *layer);
+
+void            gimp_layer_set_composite_space (GimpLayer            *layer,
+                                                GimpLayerColorSpace   composite_space,
+                                                gboolean              push_undo);
+GimpLayerColorSpace
+                gimp_layer_get_composite_space (GimpLayer            *layer);
+GimpLayerColorSpace
+           gimp_layer_get_real_composite_space (GimpLayer            *layer);
+
+void            gimp_layer_set_composite_mode  (GimpLayer            *layer,
+                                                GimpLayerCompositeMode  composite_mode,
+                                                gboolean              push_undo);
+GimpLayerCompositeMode
+                gimp_layer_get_composite_mode  (GimpLayer            *layer);
+GimpLayerCompositeMode
+           gimp_layer_get_real_composite_mode  (GimpLayer            *layer);
+
+void            gimp_layer_get_effective_mode  (GimpLayer            *layer,
+                                                GimpLayerMode          *mode,
+                                                GimpLayerColorSpace    *blend_space,
+                                                GimpLayerColorSpace    *composite_space,
+                                                GimpLayerCompositeMode *composite_mode);
+
+gboolean      gimp_layer_get_excludes_backdrop (GimpLayer            *layer);
+
+void            gimp_layer_set_lock_alpha      (GimpLayer            *layer,
+                                                gboolean              lock_alpha,
+                                                gboolean              push_undo);
+gboolean        gimp_layer_get_lock_alpha      (GimpLayer            *layer);
+gboolean        gimp_layer_can_lock_alpha      (GimpLayer            *layer);
+
+
+/*  protected  */
+
+void          gimp_layer_update_effective_mode (GimpLayer            *layer);
+void       gimp_layer_update_excludes_backdrop (GimpLayer            *layer);
+
+
+#endif /* __GIMP_LAYER_H__ */
diff --git a/app/core/gimplayermask.c b/app/core/gimplayermask.c
new file mode 100644
index 0000000..ec0dbfb
--- /dev/null
+++ b/app/core/gimplayermask.c
@@ -0,0 +1,297 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gegl/gimp-babl.h"
+
+#include "gimperror.h"
+#include "gimpimage.h"
+#include "gimplayer.h"
+#include "gimplayermask.h"
+
+#include "gimp-intl.h"
+
+
+static void            gimp_layer_mask_preview_freeze       (GimpViewable      *viewable);
+static void            gimp_layer_mask_preview_thaw         (GimpViewable      *viewable);
+
+static gboolean        gimp_layer_mask_is_attached          (GimpItem          *item);
+static gboolean        gimp_layer_mask_is_content_locked    (GimpItem          *item);
+static gboolean        gimp_layer_mask_is_position_locked   (GimpItem          *item);
+static GimpItemTree  * gimp_layer_mask_get_tree             (GimpItem          *item);
+static GimpItem      * gimp_layer_mask_duplicate            (GimpItem          *item,
+                                                             GType              new_type);
+static gboolean        gimp_layer_mask_rename               (GimpItem          *item,
+                                                             const gchar       *new_name,
+                                                             const gchar       *undo_desc,
+                                                             GError           **error);
+
+static void            gimp_layer_mask_bounding_box_changed (GimpDrawable      *drawable);
+static void            gimp_layer_mask_convert_type         (GimpDrawable      *drawable,
+                                                             GimpImage         *dest_image,
+                                                             const Babl        *new_format,
+                                                             GimpColorProfile  *dest_profile,
+                                                             GeglDitherMethod   layer_dither_type,
+                                                             GeglDitherMethod   mask_dither_type,
+                                                             gboolean           push_undo,
+                                                             GimpProgress      *progress);
+
+
+G_DEFINE_TYPE (GimpLayerMask, gimp_layer_mask, GIMP_TYPE_CHANNEL)
+
+#define parent_class gimp_layer_mask_parent_class
+
+
+static void
+gimp_layer_mask_class_init (GimpLayerMaskClass *klass)
+{
+  GimpViewableClass *viewable_class = GIMP_VIEWABLE_CLASS (klass);
+  GimpItemClass     *item_class     = GIMP_ITEM_CLASS (klass);
+  GimpDrawableClass *drawable_class = GIMP_DRAWABLE_CLASS (klass);
+
+  viewable_class->default_icon_name = "gimp-layer-mask";
+
+  viewable_class->preview_freeze       = gimp_layer_mask_preview_freeze;
+  viewable_class->preview_thaw         = gimp_layer_mask_preview_thaw;
+
+  item_class->is_attached              = gimp_layer_mask_is_attached;
+  item_class->is_content_locked        = gimp_layer_mask_is_content_locked;
+  item_class->is_position_locked       = gimp_layer_mask_is_position_locked;
+  item_class->get_tree                 = gimp_layer_mask_get_tree;
+  item_class->duplicate                = gimp_layer_mask_duplicate;
+  item_class->rename                   = gimp_layer_mask_rename;
+  item_class->translate_desc           = C_("undo-type", "Move Layer Mask");
+  item_class->to_selection_desc        = C_("undo-type", "Layer Mask to Selection");
+
+  drawable_class->bounding_box_changed = gimp_layer_mask_bounding_box_changed;
+  drawable_class->convert_type         = gimp_layer_mask_convert_type;
+}
+
+static void
+gimp_layer_mask_init (GimpLayerMask *layer_mask)
+{
+  layer_mask->layer = NULL;
+}
+
+static void
+gimp_layer_mask_preview_freeze (GimpViewable *viewable)
+{
+  GimpLayerMask *mask  = GIMP_LAYER_MASK (viewable);
+  GimpLayer     *layer = gimp_layer_mask_get_layer (mask);
+
+  if (layer)
+    {
+      GimpViewable *parent = gimp_viewable_get_parent (GIMP_VIEWABLE (layer));
+
+      if (! parent && gimp_item_is_attached (GIMP_ITEM (layer)))
+        parent = GIMP_VIEWABLE (gimp_item_get_image (GIMP_ITEM (layer)));
+
+      if (parent)
+        gimp_viewable_preview_freeze (parent);
+    }
+}
+
+static void
+gimp_layer_mask_preview_thaw (GimpViewable *viewable)
+{
+  GimpLayerMask *mask  = GIMP_LAYER_MASK (viewable);
+  GimpLayer     *layer = gimp_layer_mask_get_layer (mask);
+
+  if (layer)
+    {
+      GimpViewable *parent = gimp_viewable_get_parent (GIMP_VIEWABLE (layer));
+
+      if (! parent && gimp_item_is_attached (GIMP_ITEM (layer)))
+        parent = GIMP_VIEWABLE (gimp_item_get_image (GIMP_ITEM (layer)));
+
+      if (parent)
+        gimp_viewable_preview_thaw (parent);
+    }
+}
+
+static gboolean
+gimp_layer_mask_is_content_locked (GimpItem *item)
+{
+  GimpLayerMask *mask  = GIMP_LAYER_MASK (item);
+  GimpLayer     *layer = gimp_layer_mask_get_layer (mask);
+
+  if (layer)
+    return gimp_item_is_content_locked (GIMP_ITEM (layer));
+
+  return FALSE;
+}
+
+static gboolean
+gimp_layer_mask_is_position_locked (GimpItem *item)
+{
+  GimpLayerMask *mask  = GIMP_LAYER_MASK (item);
+  GimpLayer     *layer = gimp_layer_mask_get_layer (mask);
+
+  if (layer)
+    return gimp_item_is_position_locked (GIMP_ITEM (layer));
+
+  return FALSE;
+}
+
+static gboolean
+gimp_layer_mask_is_attached (GimpItem *item)
+{
+  GimpLayerMask *mask  = GIMP_LAYER_MASK (item);
+  GimpLayer     *layer = gimp_layer_mask_get_layer (mask);
+
+  return (GIMP_IS_IMAGE (gimp_item_get_image (item)) &&
+          GIMP_IS_LAYER (layer)                      &&
+          gimp_layer_get_mask (layer) == mask        &&
+          gimp_item_is_attached (GIMP_ITEM (layer)));
+}
+
+static GimpItemTree *
+gimp_layer_mask_get_tree (GimpItem *item)
+{
+  return NULL;
+}
+
+static GimpItem *
+gimp_layer_mask_duplicate (GimpItem *item,
+                           GType     new_type)
+{
+  GimpItem *new_item;
+
+  g_return_val_if_fail (g_type_is_a (new_type, GIMP_TYPE_DRAWABLE), NULL);
+
+  new_item = GIMP_ITEM_CLASS (parent_class)->duplicate (item, new_type);
+
+  return new_item;
+}
+
+static gboolean
+gimp_layer_mask_rename (GimpItem     *item,
+                        const gchar  *new_name,
+                        const gchar  *undo_desc,
+                        GError      **error)
+{
+  /* reject renaming, layer masks are always named "<layer name> mask"  */
+
+  g_set_error (error, GIMP_ERROR, GIMP_FAILED,
+               _("Cannot rename layer masks."));
+
+  return FALSE;
+}
+
+static void
+gimp_layer_mask_bounding_box_changed (GimpDrawable *drawable)
+{
+  GimpLayerMask *mask  = GIMP_LAYER_MASK (drawable);
+  GimpLayer     *layer = gimp_layer_mask_get_layer (mask);
+
+  if (GIMP_DRAWABLE_CLASS (parent_class)->bounding_box_changed)
+    GIMP_DRAWABLE_CLASS (parent_class)->bounding_box_changed (drawable);
+
+  if (layer)
+    gimp_drawable_update_bounding_box (GIMP_DRAWABLE (layer));
+}
+
+static void
+gimp_layer_mask_convert_type (GimpDrawable      *drawable,
+                              GimpImage         *dest_image,
+                              const Babl        *new_format,
+                              GimpColorProfile  *dest_profile,
+                              GeglDitherMethod   layer_dither_type,
+                              GeglDitherMethod   mask_dither_type,
+                              gboolean           push_undo,
+                              GimpProgress      *progress)
+{
+  new_format =
+    gimp_babl_mask_format (gimp_babl_format_get_precision (new_format));
+
+  GIMP_DRAWABLE_CLASS (parent_class)->convert_type (drawable, dest_image,
+                                                    new_format,
+                                                    dest_profile,
+                                                    layer_dither_type,
+                                                    mask_dither_type,
+                                                    push_undo,
+                                                    progress);
+}
+
+GimpLayerMask *
+gimp_layer_mask_new (GimpImage     *image,
+                     gint           width,
+                     gint           height,
+                     const gchar   *name,
+                     const GimpRGB *color)
+{
+  GimpLayerMask *layer_mask;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (width > 0, NULL);
+  g_return_val_if_fail (height > 0, NULL);
+  g_return_val_if_fail (color != NULL, NULL);
+
+  layer_mask =
+    GIMP_LAYER_MASK (gimp_drawable_new (GIMP_TYPE_LAYER_MASK,
+                                        image, name,
+                                        0, 0, width, height,
+                                        gimp_image_get_mask_format (image)));
+
+  /*  set the layer_mask color and opacity  */
+  gimp_channel_set_color (GIMP_CHANNEL (layer_mask), color, FALSE);
+  gimp_channel_set_show_masked (GIMP_CHANNEL (layer_mask), TRUE);
+
+  /*  selection mask variables  */
+  GIMP_CHANNEL (layer_mask)->x2 = width;
+  GIMP_CHANNEL (layer_mask)->y2 = height;
+
+  return layer_mask;
+}
+
+void
+gimp_layer_mask_set_layer (GimpLayerMask *layer_mask,
+                           GimpLayer     *layer)
+{
+  g_return_if_fail (GIMP_IS_LAYER_MASK (layer_mask));
+  g_return_if_fail (layer == NULL || GIMP_IS_LAYER (layer));
+
+  layer_mask->layer = layer;
+
+  if (layer)
+    {
+      gchar *mask_name;
+      gint   offset_x;
+      gint   offset_y;
+
+      gimp_item_get_offset (GIMP_ITEM (layer), &offset_x, &offset_y);
+      gimp_item_set_offset (GIMP_ITEM (layer_mask), offset_x, offset_y);
+
+      mask_name = g_strdup_printf (_("%s mask"), gimp_object_get_name (layer));
+
+      gimp_object_take_name (GIMP_OBJECT (layer_mask), mask_name);
+    }
+}
+
+GimpLayer *
+gimp_layer_mask_get_layer (GimpLayerMask *layer_mask)
+{
+  g_return_val_if_fail (GIMP_IS_LAYER_MASK (layer_mask), NULL);
+
+  return layer_mask->layer;
+}
diff --git a/app/core/gimplayermask.h b/app/core/gimplayermask.h
new file mode 100644
index 0000000..5ee77fd
--- /dev/null
+++ b/app/core/gimplayermask.h
@@ -0,0 +1,61 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_LAYER_MASK_H__
+#define __GIMP_LAYER_MASK_H__
+
+
+#include "gimpchannel.h"
+
+
+#define GIMP_TYPE_LAYER_MASK            (gimp_layer_mask_get_type ())
+#define GIMP_LAYER_MASK(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_LAYER_MASK, GimpLayerMask))
+#define GIMP_LAYER_MASK_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_LAYER_MASK, GimpLayerMaskClass))
+#define GIMP_IS_LAYER_MASK(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_LAYER_MASK))
+#define GIMP_IS_LAYER_MASK_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_LAYER_MASK))
+#define GIMP_LAYER_MASK_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_LAYER_MASK, GimpLayerMaskClass))
+
+
+typedef struct _GimpLayerMaskClass  GimpLayerMaskClass;
+
+struct _GimpLayerMask
+{
+  GimpChannel  parent_instance;
+
+  GimpLayer   *layer;
+};
+
+struct _GimpLayerMaskClass
+{
+  GimpChannelClass  parent_class;
+};
+
+
+GType           gimp_layer_mask_get_type  (void) G_GNUC_CONST;
+
+GimpLayerMask * gimp_layer_mask_new       (GimpImage     *image,
+                                           gint           width,
+                                           gint           height,
+                                           const gchar   *name,
+                                           const GimpRGB *color);
+
+void            gimp_layer_mask_set_layer (GimpLayerMask *layer_mask,
+                                           GimpLayer     *layer);
+GimpLayer     * gimp_layer_mask_get_layer (GimpLayerMask *layer_mask);
+
+
+#endif /* __GIMP_LAYER_MASK_H__ */
diff --git a/app/core/gimplayermaskpropundo.c b/app/core/gimplayermaskpropundo.c
new file mode 100644
index 0000000..7913202
--- /dev/null
+++ b/app/core/gimplayermaskpropundo.c
@@ -0,0 +1,122 @@
+/* Gimp - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gimplayer.h"
+#include "gimplayermaskpropundo.h"
+
+
+static void   gimp_layer_mask_prop_undo_constructed (GObject             *object);
+
+static void   gimp_layer_mask_prop_undo_pop         (GimpUndo            *undo,
+                                                     GimpUndoMode         undo_mode,
+                                                     GimpUndoAccumulator *accum);
+
+
+G_DEFINE_TYPE (GimpLayerMaskPropUndo, gimp_layer_mask_prop_undo,
+               GIMP_TYPE_ITEM_UNDO)
+
+#define parent_class gimp_layer_mask_prop_undo_parent_class
+
+
+static void
+gimp_layer_mask_prop_undo_class_init (GimpLayerMaskPropUndoClass *klass)
+{
+  GObjectClass  *object_class = G_OBJECT_CLASS (klass);
+  GimpUndoClass *undo_class   = GIMP_UNDO_CLASS (klass);
+
+  object_class->constructed = gimp_layer_mask_prop_undo_constructed;
+
+  undo_class->pop           = gimp_layer_mask_prop_undo_pop;
+}
+
+static void
+gimp_layer_mask_prop_undo_init (GimpLayerMaskPropUndo *undo)
+{
+}
+
+static void
+gimp_layer_mask_prop_undo_constructed (GObject *object)
+{
+  GimpLayerMaskPropUndo *layer_mask_prop_undo;
+  GimpLayer             *layer;
+
+  layer_mask_prop_undo = GIMP_LAYER_MASK_PROP_UNDO (object);
+
+  G_OBJECT_CLASS (parent_class)->constructed (object);
+
+  gimp_assert (GIMP_IS_LAYER (GIMP_ITEM_UNDO (object)->item));
+
+  layer = GIMP_LAYER (GIMP_ITEM_UNDO (object)->item);
+
+  switch (GIMP_UNDO (object)->undo_type)
+    {
+    case GIMP_UNDO_LAYER_MASK_APPLY:
+      layer_mask_prop_undo->apply = gimp_layer_get_apply_mask (layer);
+      break;
+
+    case GIMP_UNDO_LAYER_MASK_SHOW:
+      layer_mask_prop_undo->show = gimp_layer_get_show_mask (layer);
+      break;
+
+    default:
+      g_return_if_reached ();
+    }
+}
+
+static void
+gimp_layer_mask_prop_undo_pop (GimpUndo            *undo,
+                               GimpUndoMode         undo_mode,
+                               GimpUndoAccumulator *accum)
+{
+  GimpLayerMaskPropUndo *layer_mask_prop_undo = GIMP_LAYER_MASK_PROP_UNDO (undo);
+  GimpLayer             *layer                = GIMP_LAYER (GIMP_ITEM_UNDO (undo)->item);
+
+  GIMP_UNDO_CLASS (parent_class)->pop (undo, undo_mode, accum);
+
+  switch (undo->undo_type)
+    {
+    case GIMP_UNDO_LAYER_MASK_APPLY:
+      {
+        gboolean apply;
+
+        apply = gimp_layer_get_apply_mask (layer);
+        gimp_layer_set_apply_mask (layer, layer_mask_prop_undo->apply, FALSE);
+        layer_mask_prop_undo->apply = apply;
+      }
+      break;
+
+    case GIMP_UNDO_LAYER_MASK_SHOW:
+      {
+        gboolean show;
+
+        show = gimp_layer_get_show_mask (layer);
+        gimp_layer_set_show_mask (layer, layer_mask_prop_undo->show, FALSE);
+        layer_mask_prop_undo->show = show;
+      }
+      break;
+
+    default:
+      g_return_if_reached ();
+    }
+}
diff --git a/app/core/gimplayermaskpropundo.h b/app/core/gimplayermaskpropundo.h
new file mode 100644
index 0000000..a416e43
--- /dev/null
+++ b/app/core/gimplayermaskpropundo.h
@@ -0,0 +1,53 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_LAYER_MASK_PROP_UNDO_H__
+#define __GIMP_LAYER_MASK_PROP_UNDO_H__
+
+
+#include "gimpitemundo.h"
+
+
+#define GIMP_TYPE_LAYER_MASK_PROP_UNDO            (gimp_layer_mask_prop_undo_get_type ())
+#define GIMP_LAYER_MASK_PROP_UNDO(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_LAYER_MASK_PROP_UNDO, GimpLayerMaskPropUndo))
+#define GIMP_LAYER_MASK_PROP_UNDO_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_LAYER_MASK_PROP_UNDO, GimpLayerMaskPropUndoClass))
+#define GIMP_IS_LAYER_MASK_PROP_UNDO(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_LAYER_MASK_PROP_UNDO))
+#define GIMP_IS_LAYER_MASK_PROP_UNDO_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_LAYER_MASK_PROP_UNDO))
+#define GIMP_LAYER_MASK_PROP_UNDO_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_LAYER_MASK_PROP_UNDO, GimpLayerMaskPropUndoClass))
+
+
+typedef struct _GimpLayerMaskPropUndo      GimpLayerMaskPropUndo;
+typedef struct _GimpLayerMaskPropUndoClass GimpLayerMaskPropUndoClass;
+
+struct _GimpLayerMaskPropUndo
+{
+  GimpItemUndo  parent_instance;
+
+  gboolean      apply;
+  gboolean      show;
+};
+
+struct _GimpLayerMaskPropUndoClass
+{
+  GimpItemUndoClass  parent_class;
+};
+
+
+GType   gimp_layer_mask_prop_undo_get_type (void) G_GNUC_CONST;
+
+
+#endif /* __GIMP_LAYER_MASK_PROP_UNDO_H__ */
diff --git a/app/core/gimplayermaskundo.c b/app/core/gimplayermaskundo.c
new file mode 100644
index 0000000..cc49eb7
--- /dev/null
+++ b/app/core/gimplayermaskundo.c
@@ -0,0 +1,195 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gimpimage.h"
+#include "gimplayer.h"
+#include "gimplayermask.h"
+#include "gimplayermaskundo.h"
+
+
+enum
+{
+  PROP_0,
+  PROP_LAYER_MASK
+};
+
+
+static void     gimp_layer_mask_undo_constructed  (GObject             *object);
+static void     gimp_layer_mask_undo_set_property (GObject             *object,
+                                                   guint                property_id,
+                                                   const GValue        *value,
+                                                   GParamSpec          *pspec);
+static void     gimp_layer_mask_undo_get_property (GObject             *object,
+                                                   guint                property_id,
+                                                   GValue              *value,
+                                                   GParamSpec          *pspec);
+
+static gint64   gimp_layer_mask_undo_get_memsize  (GimpObject          *object,
+                                                   gint64              *gui_size);
+
+static void     gimp_layer_mask_undo_pop          (GimpUndo            *undo,
+                                                   GimpUndoMode         undo_mode,
+                                                   GimpUndoAccumulator *accum);
+static void     gimp_layer_mask_undo_free         (GimpUndo            *undo,
+                                                   GimpUndoMode         undo_mode);
+
+
+G_DEFINE_TYPE (GimpLayerMaskUndo, gimp_layer_mask_undo, GIMP_TYPE_ITEM_UNDO)
+
+#define parent_class gimp_layer_mask_undo_parent_class
+
+
+static void
+gimp_layer_mask_undo_class_init (GimpLayerMaskUndoClass *klass)
+{
+  GObjectClass    *object_class      = G_OBJECT_CLASS (klass);
+  GimpObjectClass *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+  GimpUndoClass   *undo_class        = GIMP_UNDO_CLASS (klass);
+
+  object_class->constructed      = gimp_layer_mask_undo_constructed;
+  object_class->set_property     = gimp_layer_mask_undo_set_property;
+  object_class->get_property     = gimp_layer_mask_undo_get_property;
+
+  gimp_object_class->get_memsize = gimp_layer_mask_undo_get_memsize;
+
+  undo_class->pop                = gimp_layer_mask_undo_pop;
+  undo_class->free               = gimp_layer_mask_undo_free;
+
+  g_object_class_install_property (object_class, PROP_LAYER_MASK,
+                                   g_param_spec_object ("layer-mask", NULL, NULL,
+                                                        GIMP_TYPE_LAYER_MASK,
+                                                        GIMP_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT_ONLY));
+}
+
+static void
+gimp_layer_mask_undo_init (GimpLayerMaskUndo *undo)
+{
+}
+
+static void
+gimp_layer_mask_undo_constructed (GObject *object)
+{
+  GimpLayerMaskUndo *layer_mask_undo = GIMP_LAYER_MASK_UNDO (object);
+
+  G_OBJECT_CLASS (parent_class)->constructed (object);
+
+  gimp_assert (GIMP_IS_LAYER (GIMP_ITEM_UNDO (object)->item));
+  gimp_assert (GIMP_IS_LAYER_MASK (layer_mask_undo->layer_mask));
+}
+
+static void
+gimp_layer_mask_undo_set_property (GObject      *object,
+                                   guint         property_id,
+                                   const GValue *value,
+                                   GParamSpec   *pspec)
+{
+  GimpLayerMaskUndo *layer_mask_undo = GIMP_LAYER_MASK_UNDO (object);
+
+  switch (property_id)
+    {
+    case PROP_LAYER_MASK:
+      layer_mask_undo->layer_mask = g_value_dup_object (value);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_layer_mask_undo_get_property (GObject    *object,
+                                   guint       property_id,
+                                   GValue     *value,
+                                   GParamSpec *pspec)
+{
+  GimpLayerMaskUndo *layer_mask_undo = GIMP_LAYER_MASK_UNDO (object);
+
+  switch (property_id)
+    {
+    case PROP_LAYER_MASK:
+      g_value_set_object (value, layer_mask_undo->layer_mask);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static gint64
+gimp_layer_mask_undo_get_memsize (GimpObject *object,
+                                  gint64     *gui_size)
+{
+  GimpLayerMaskUndo *layer_mask_undo = GIMP_LAYER_MASK_UNDO (object);
+  GimpLayer         *layer           = GIMP_LAYER (GIMP_ITEM_UNDO (object)->item);
+  gint64             memsize         = 0;
+
+  /* don't use !gimp_item_is_attached() here */
+  if (gimp_layer_get_mask (layer) != layer_mask_undo->layer_mask)
+    memsize += gimp_object_get_memsize (GIMP_OBJECT (layer_mask_undo->layer_mask),
+                                        gui_size);
+
+  return memsize + GIMP_OBJECT_CLASS (parent_class)->get_memsize (object,
+                                                                  gui_size);
+}
+
+static void
+gimp_layer_mask_undo_pop (GimpUndo            *undo,
+                          GimpUndoMode         undo_mode,
+                          GimpUndoAccumulator *accum)
+{
+  GimpLayerMaskUndo *layer_mask_undo = GIMP_LAYER_MASK_UNDO (undo);
+  GimpLayer         *layer           = GIMP_LAYER (GIMP_ITEM_UNDO (undo)->item);
+
+  GIMP_UNDO_CLASS (parent_class)->pop (undo, undo_mode, accum);
+
+  if ((undo_mode       == GIMP_UNDO_MODE_UNDO &&
+       undo->undo_type == GIMP_UNDO_LAYER_MASK_ADD) ||
+      (undo_mode       == GIMP_UNDO_MODE_REDO &&
+       undo->undo_type == GIMP_UNDO_LAYER_MASK_REMOVE))
+    {
+      /*  remove layer mask  */
+
+      gimp_layer_apply_mask (layer, GIMP_MASK_DISCARD, FALSE);
+    }
+  else
+    {
+      /*  restore layer mask  */
+
+      gimp_layer_add_mask (layer, layer_mask_undo->layer_mask, FALSE, NULL);
+    }
+}
+
+static void
+gimp_layer_mask_undo_free (GimpUndo     *undo,
+                           GimpUndoMode  undo_mode)
+{
+  GimpLayerMaskUndo *layer_mask_undo = GIMP_LAYER_MASK_UNDO (undo);
+
+  g_clear_object (&layer_mask_undo->layer_mask);
+
+  GIMP_UNDO_CLASS (parent_class)->free (undo, undo_mode);
+}
diff --git a/app/core/gimplayermaskundo.h b/app/core/gimplayermaskundo.h
new file mode 100644
index 0000000..c8591c1
--- /dev/null
+++ b/app/core/gimplayermaskundo.h
@@ -0,0 +1,52 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_LAYER_MASK_UNDO_H__
+#define __GIMP_LAYER_MASK_UNDO_H__
+
+
+#include "gimpitemundo.h"
+
+
+#define GIMP_TYPE_LAYER_MASK_UNDO            (gimp_layer_mask_undo_get_type ())
+#define GIMP_LAYER_MASK_UNDO(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_LAYER_MASK_UNDO, GimpLayerMaskUndo))
+#define GIMP_LAYER_MASK_UNDO_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_LAYER_MASK_UNDO, GimpLayerMaskUndoClass))
+#define GIMP_IS_LAYER_MASK_UNDO(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_LAYER_MASK_UNDO))
+#define GIMP_IS_LAYER_MASK_UNDO_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_LAYER_MASK_UNDO))
+#define GIMP_LAYER_MASK_UNDO_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_LAYER_MASK_UNDO, GimpLayerMaskUndoClass))
+
+
+typedef struct _GimpLayerMaskUndo      GimpLayerMaskUndo;
+typedef struct _GimpLayerMaskUndoClass GimpLayerMaskUndoClass;
+
+struct _GimpLayerMaskUndo
+{
+  GimpItemUndo   parent_instance;
+
+  GimpLayerMask *layer_mask;
+};
+
+struct _GimpLayerMaskUndoClass
+{
+  GimpItemUndoClass  parent_class;
+};
+
+
+GType   gimp_layer_mask_undo_get_type (void) G_GNUC_CONST;
+
+
+#endif /* __GIMP_LAYER_MASK_UNDO_H__ */
diff --git a/app/core/gimplayerpropundo.c b/app/core/gimplayerpropundo.c
new file mode 100644
index 0000000..73e3e02
--- /dev/null
+++ b/app/core/gimplayerpropundo.c
@@ -0,0 +1,157 @@
+/* Gimp - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+
+#include "core-types.h"
+
+#include "gimpimage.h"
+#include "gimplayer.h"
+#include "gimplayerpropundo.h"
+
+
+static void   gimp_layer_prop_undo_constructed (GObject             *object);
+
+static void   gimp_layer_prop_undo_pop         (GimpUndo            *undo,
+                                                GimpUndoMode         undo_mode,
+                                                GimpUndoAccumulator *accum);
+
+
+G_DEFINE_TYPE (GimpLayerPropUndo, gimp_layer_prop_undo, GIMP_TYPE_ITEM_UNDO)
+
+#define parent_class gimp_layer_prop_undo_parent_class
+
+
+static void
+gimp_layer_prop_undo_class_init (GimpLayerPropUndoClass *klass)
+{
+  GObjectClass  *object_class = G_OBJECT_CLASS (klass);
+  GimpUndoClass *undo_class   = GIMP_UNDO_CLASS (klass);
+
+  object_class->constructed = gimp_layer_prop_undo_constructed;
+
+  undo_class->pop           = gimp_layer_prop_undo_pop;
+}
+
+static void
+gimp_layer_prop_undo_init (GimpLayerPropUndo *undo)
+{
+}
+
+static void
+gimp_layer_prop_undo_constructed (GObject *object)
+{
+  GimpLayerPropUndo *layer_prop_undo = GIMP_LAYER_PROP_UNDO (object);
+  GimpLayer         *layer;
+
+  G_OBJECT_CLASS (parent_class)->constructed (object);
+
+  gimp_assert (GIMP_IS_LAYER (GIMP_ITEM_UNDO (object)->item));
+
+  layer = GIMP_LAYER (GIMP_ITEM_UNDO (object)->item);
+
+  switch (GIMP_UNDO (object)->undo_type)
+    {
+    case GIMP_UNDO_LAYER_MODE:
+      layer_prop_undo->mode            = gimp_layer_get_mode (layer);
+      layer_prop_undo->blend_space     = gimp_layer_get_blend_space (layer);
+      layer_prop_undo->composite_space = gimp_layer_get_composite_space (layer);
+      layer_prop_undo->composite_mode  = gimp_layer_get_composite_mode (layer);
+      break;
+
+    case GIMP_UNDO_LAYER_OPACITY:
+      layer_prop_undo->opacity = gimp_layer_get_opacity (layer);
+      break;
+
+    case GIMP_UNDO_LAYER_LOCK_ALPHA:
+      layer_prop_undo->lock_alpha = gimp_layer_get_lock_alpha (layer);
+      break;
+
+    default:
+      g_return_if_reached ();
+    }
+}
+
+static void
+gimp_layer_prop_undo_pop (GimpUndo            *undo,
+                          GimpUndoMode         undo_mode,
+                          GimpUndoAccumulator *accum)
+{
+  GimpLayerPropUndo *layer_prop_undo = GIMP_LAYER_PROP_UNDO (undo);
+  GimpLayer         *layer           = GIMP_LAYER (GIMP_ITEM_UNDO (undo)->item);
+
+  GIMP_UNDO_CLASS (parent_class)->pop (undo, undo_mode, accum);
+
+  switch (undo->undo_type)
+    {
+    case GIMP_UNDO_LAYER_MODE:
+      {
+        GimpLayerMode          mode;
+        GimpLayerColorSpace    blend_space;
+        GimpLayerColorSpace    composite_space;
+        GimpLayerCompositeMode composite_mode;
+
+        mode            = gimp_layer_get_mode (layer);
+        blend_space     = gimp_layer_get_blend_space (layer);
+        composite_space = gimp_layer_get_composite_space (layer);
+        composite_mode  = gimp_layer_get_composite_mode (layer);
+
+        gimp_layer_set_mode            (layer, layer_prop_undo->mode,
+                                        FALSE);
+        gimp_layer_set_blend_space     (layer, layer_prop_undo->blend_space,
+                                        FALSE);
+        gimp_layer_set_composite_space (layer, layer_prop_undo->composite_space,
+                                        FALSE);
+        gimp_layer_set_composite_mode  (layer, layer_prop_undo->composite_mode,
+                                        FALSE);
+
+        layer_prop_undo->mode            = mode;
+        layer_prop_undo->blend_space     = blend_space;
+        layer_prop_undo->composite_space = composite_space;
+        layer_prop_undo->composite_mode  = composite_mode;
+      }
+      break;
+
+    case GIMP_UNDO_LAYER_OPACITY:
+      {
+        gdouble opacity;
+
+        opacity = gimp_layer_get_opacity (layer);
+        gimp_layer_set_opacity (layer, layer_prop_undo->opacity, FALSE);
+        layer_prop_undo->opacity = opacity;
+      }
+      break;
+
+    case GIMP_UNDO_LAYER_LOCK_ALPHA:
+      {
+        gboolean lock_alpha;
+
+        lock_alpha = gimp_layer_get_lock_alpha (layer);
+        gimp_layer_set_lock_alpha (layer, layer_prop_undo->lock_alpha, FALSE);
+        layer_prop_undo->lock_alpha = lock_alpha;
+      }
+      break;
+
+    default:
+      g_return_if_reached ();
+    }
+}
diff --git a/app/core/gimplayerpropundo.h b/app/core/gimplayerpropundo.h
new file mode 100644
index 0000000..5a3b478
--- /dev/null
+++ b/app/core/gimplayerpropundo.h
@@ -0,0 +1,57 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_LAYER_PROP_UNDO_H__
+#define __GIMP_LAYER_PROP_UNDO_H__
+
+
+#include "gimpitemundo.h"
+
+
+#define GIMP_TYPE_LAYER_PROP_UNDO            (gimp_layer_prop_undo_get_type ())
+#define GIMP_LAYER_PROP_UNDO(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_LAYER_PROP_UNDO, GimpLayerPropUndo))
+#define GIMP_LAYER_PROP_UNDO_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_LAYER_PROP_UNDO, GimpLayerPropUndoClass))
+#define GIMP_IS_LAYER_PROP_UNDO(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_LAYER_PROP_UNDO))
+#define GIMP_IS_LAYER_PROP_UNDO_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_LAYER_PROP_UNDO))
+#define GIMP_LAYER_PROP_UNDO_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_LAYER_PROP_UNDO, GimpLayerPropUndoClass))
+
+
+typedef struct _GimpLayerPropUndo      GimpLayerPropUndo;
+typedef struct _GimpLayerPropUndoClass GimpLayerPropUndoClass;
+
+struct _GimpLayerPropUndo
+{
+  GimpItemUndo            parent_instance;
+
+  GimpLayerMode           mode;
+  GimpLayerColorSpace     blend_space;
+  GimpLayerColorSpace     composite_space;
+  GimpLayerCompositeMode  composite_mode;
+  gdouble                 opacity;
+  gboolean                lock_alpha;
+};
+
+struct _GimpLayerPropUndoClass
+{
+  GimpItemUndoClass  parent_class;
+};
+
+
+GType   gimp_layer_prop_undo_get_type (void) G_GNUC_CONST;
+
+
+#endif /* __GIMP_LAYER_PROP_UNDO_H__ */
diff --git a/app/core/gimplayerstack.c b/app/core/gimplayerstack.c
new file mode 100644
index 0000000..1540189
--- /dev/null
+++ b/app/core/gimplayerstack.c
@@ -0,0 +1,243 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1997 Spencer Kimball and Peter Mattis
+ *
+ * gimplayerstack.c
+ * Copyright (C) 2017 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gimplayer.h"
+#include "gimplayerstack.h"
+
+
+/*  local function prototypes  */
+
+static void   gimp_layer_stack_constructed             (GObject       *object);
+
+static void   gimp_layer_stack_add                     (GimpContainer *container,
+                                                        GimpObject    *object);
+static void   gimp_layer_stack_remove                  (GimpContainer *container,
+                                                        GimpObject    *object);
+static void   gimp_layer_stack_reorder                 (GimpContainer *container,
+                                                        GimpObject    *object,
+                                                        gint           new_index);
+
+static void   gimp_layer_stack_layer_active            (GimpLayer      *layer,
+                                                        GimpLayerStack *stack);
+static void   gimp_layer_stack_layer_excludes_backdrop (GimpLayer      *layer,
+                                                        GimpLayerStack *stack);
+
+static void   gimp_layer_stack_update_backdrop         (GimpLayerStack *stack,
+                                                        GimpLayer      *layer,
+                                                        gboolean        ignore_active,
+                                                        gboolean        ignore_excludes_backdrop);
+static void   gimp_layer_stack_update_range            (GimpLayerStack *stack,
+                                                        gint            first,
+                                                        gint            last);
+
+
+G_DEFINE_TYPE (GimpLayerStack, gimp_layer_stack, GIMP_TYPE_DRAWABLE_STACK)
+
+#define parent_class gimp_layer_stack_parent_class
+
+
+static void
+gimp_layer_stack_class_init (GimpLayerStackClass *klass)
+{
+  GObjectClass       *object_class    = G_OBJECT_CLASS (klass);
+  GimpContainerClass *container_class = GIMP_CONTAINER_CLASS (klass);
+
+  object_class->constructed = gimp_layer_stack_constructed;
+
+  container_class->add      = gimp_layer_stack_add;
+  container_class->remove   = gimp_layer_stack_remove;
+  container_class->reorder  = gimp_layer_stack_reorder;
+}
+
+static void
+gimp_layer_stack_init (GimpLayerStack *stack)
+{
+}
+
+static void
+gimp_layer_stack_constructed (GObject *object)
+{
+  GimpContainer *container = GIMP_CONTAINER (object);
+
+  G_OBJECT_CLASS (parent_class)->constructed (object);
+
+  gimp_assert (g_type_is_a (gimp_container_get_children_type (container),
+                            GIMP_TYPE_LAYER));
+
+  gimp_container_add_handler (container, "active-changed",
+                              G_CALLBACK (gimp_layer_stack_layer_active),
+                              container);
+  gimp_container_add_handler (container, "excludes-backdrop-changed",
+                              G_CALLBACK (gimp_layer_stack_layer_excludes_backdrop),
+                              container);
+}
+
+static void
+gimp_layer_stack_add (GimpContainer *container,
+                      GimpObject    *object)
+{
+  GimpLayerStack *stack = GIMP_LAYER_STACK (container);
+
+  GIMP_CONTAINER_CLASS (parent_class)->add (container, object);
+
+  gimp_layer_stack_update_backdrop (stack, GIMP_LAYER (object), FALSE, FALSE);
+}
+
+static void
+gimp_layer_stack_remove (GimpContainer *container,
+                         GimpObject    *object)
+{
+  GimpLayerStack *stack = GIMP_LAYER_STACK (container);
+  gboolean        update_backdrop;
+  gint            index;
+
+  update_backdrop = gimp_filter_get_active (GIMP_FILTER (object)) &&
+                    gimp_layer_get_excludes_backdrop (GIMP_LAYER (object));
+
+  if (update_backdrop)
+    index = gimp_container_get_child_index (container, object);
+
+  GIMP_CONTAINER_CLASS (parent_class)->remove (container, object);
+
+  if (update_backdrop)
+    gimp_layer_stack_update_range (stack, index, -1);
+}
+
+static void
+gimp_layer_stack_reorder (GimpContainer *container,
+                          GimpObject    *object,
+                          gint           new_index)
+{
+  GimpLayerStack *stack = GIMP_LAYER_STACK (container);
+  gboolean        update_backdrop;
+  gint            index;
+
+  update_backdrop = gimp_filter_get_active (GIMP_FILTER (object)) &&
+                    gimp_layer_get_excludes_backdrop (GIMP_LAYER (object));
+
+  if (update_backdrop)
+    index = gimp_container_get_child_index (container, object);
+
+  GIMP_CONTAINER_CLASS (parent_class)->reorder (container, object, new_index);
+
+  if (update_backdrop)
+    gimp_layer_stack_update_range (stack, index, new_index);
+}
+
+
+/*  public functions  */
+
+GimpContainer *
+gimp_layer_stack_new (GType layer_type)
+{
+  g_return_val_if_fail (g_type_is_a (layer_type, GIMP_TYPE_LAYER), NULL);
+
+  return g_object_new (GIMP_TYPE_LAYER_STACK,
+                       "name",          g_type_name (layer_type),
+                       "children-type", layer_type,
+                       "policy",        GIMP_CONTAINER_POLICY_STRONG,
+                       NULL);
+}
+
+
+/*  private functions  */
+
+static void
+gimp_layer_stack_layer_active (GimpLayer      *layer,
+                               GimpLayerStack *stack)
+{
+  gimp_layer_stack_update_backdrop (stack, layer, TRUE, FALSE);
+}
+
+static void
+gimp_layer_stack_layer_excludes_backdrop (GimpLayer      *layer,
+                                          GimpLayerStack *stack)
+{
+  gimp_layer_stack_update_backdrop (stack, layer, FALSE, TRUE);
+}
+
+static void
+gimp_layer_stack_update_backdrop (GimpLayerStack *stack,
+                                  GimpLayer      *layer,
+                                  gboolean        ignore_active,
+                                  gboolean        ignore_excludes_backdrop)
+{
+  if ((ignore_active            || gimp_filter_get_active (GIMP_FILTER (layer))) &&
+      (ignore_excludes_backdrop || gimp_layer_get_excludes_backdrop (layer)))
+    {
+      gint index;
+
+      index = gimp_container_get_child_index (GIMP_CONTAINER (stack),
+                                              GIMP_OBJECT (layer));
+
+      gimp_layer_stack_update_range (stack, index + 1, -1);
+    }
+}
+
+static void
+gimp_layer_stack_update_range (GimpLayerStack *stack,
+                               gint            first,
+                               gint            last)
+{
+  GList *iter;
+
+  g_return_if_fail (first >= 0 && last >= -1);
+
+  /* if the range is reversed, flip first and last; note that last == -1 is
+   * used to update all layers from first onward.
+   */
+  if (last >= 0 && last < first)
+    {
+      gint temp = first;
+
+      first = last + 1;
+      last  = temp + 1;
+    }
+
+  iter = gimp_item_stack_get_item_iter (GIMP_ITEM_STACK (stack));
+
+  for (iter = g_list_nth (iter, first);
+       iter && first != last;
+       iter = g_list_next (iter), first++)
+    {
+      GimpItem *item = iter->data;
+
+      if (gimp_filter_get_active (GIMP_FILTER (item)))
+        {
+          GeglRectangle bounding_box;
+
+          bounding_box = gimp_drawable_get_bounding_box (GIMP_DRAWABLE (item));
+
+          bounding_box.x += gimp_item_get_offset_x (item);
+          bounding_box.y += gimp_item_get_offset_y (item);
+
+          gimp_drawable_stack_update (GIMP_DRAWABLE_STACK (stack),
+                                      bounding_box.x,     bounding_box.y,
+                                      bounding_box.width, bounding_box.height);
+        }
+    }
+}
diff --git a/app/core/gimplayerstack.h b/app/core/gimplayerstack.h
new file mode 100644
index 0000000..598d21c
--- /dev/null
+++ b/app/core/gimplayerstack.h
@@ -0,0 +1,51 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1997 Spencer Kimball and Peter Mattis
+ *
+ * gimplayerstack.h
+ * Copyright (C) 2017 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_LAYER_STACK_H__
+#define __GIMP_LAYER_STACK_H__
+
+#include "gimpdrawablestack.h"
+
+
+#define GIMP_TYPE_LAYER_STACK            (gimp_layer_stack_get_type ())
+#define GIMP_LAYER_STACK(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_LAYER_STACK, GimpLayerStack))
+#define GIMP_LAYER_STACK_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_LAYER_STACK, GimpLayerStackClass))
+#define GIMP_IS_LAYER_STACK(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_LAYER_STACK))
+#define GIMP_IS_LAYER_STACK_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_LAYER_STACK))
+
+
+typedef struct _GimpLayerStackClass GimpLayerStackClass;
+
+struct _GimpLayerStack
+{
+  GimpDrawableStack  parent_instance;
+};
+
+struct _GimpLayerStackClass
+{
+  GimpDrawableStackClass  parent_class;
+};
+
+
+GType           gimp_layer_stack_get_type  (void) G_GNUC_CONST;
+GimpContainer * gimp_layer_stack_new       (GType layer_type);
+
+
+#endif  /*  __GIMP_LAYER_STACK_H__  */
diff --git a/app/core/gimplayerundo.c b/app/core/gimplayerundo.c
new file mode 100644
index 0000000..64a1de3
--- /dev/null
+++ b/app/core/gimplayerundo.c
@@ -0,0 +1,212 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gimpimage.h"
+#include "gimplayer.h"
+#include "gimplayerundo.h"
+
+
+enum
+{
+  PROP_0,
+  PROP_PREV_PARENT,
+  PROP_PREV_POSITION,
+  PROP_PREV_LAYER
+};
+
+
+static void     gimp_layer_undo_constructed  (GObject             *object);
+static void     gimp_layer_undo_set_property (GObject             *object,
+                                              guint                property_id,
+                                              const GValue        *value,
+                                              GParamSpec          *pspec);
+static void     gimp_layer_undo_get_property (GObject             *object,
+                                              guint                property_id,
+                                              GValue              *value,
+                                              GParamSpec          *pspec);
+
+static gint64   gimp_layer_undo_get_memsize  (GimpObject          *object,
+                                              gint64              *gui_size);
+
+static void     gimp_layer_undo_pop          (GimpUndo            *undo,
+                                              GimpUndoMode         undo_mode,
+                                              GimpUndoAccumulator *accum);
+
+
+G_DEFINE_TYPE (GimpLayerUndo, gimp_layer_undo, GIMP_TYPE_ITEM_UNDO)
+
+#define parent_class gimp_layer_undo_parent_class
+
+
+static void
+gimp_layer_undo_class_init (GimpLayerUndoClass *klass)
+{
+  GObjectClass    *object_class      = G_OBJECT_CLASS (klass);
+  GimpObjectClass *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+  GimpUndoClass   *undo_class        = GIMP_UNDO_CLASS (klass);
+
+  object_class->constructed      = gimp_layer_undo_constructed;
+  object_class->set_property     = gimp_layer_undo_set_property;
+  object_class->get_property     = gimp_layer_undo_get_property;
+
+  gimp_object_class->get_memsize = gimp_layer_undo_get_memsize;
+
+  undo_class->pop                = gimp_layer_undo_pop;
+
+  g_object_class_install_property (object_class, PROP_PREV_PARENT,
+                                   g_param_spec_object ("prev-parent",
+                                                        NULL, NULL,
+                                                        GIMP_TYPE_LAYER,
+                                                        GIMP_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT_ONLY));
+
+  g_object_class_install_property (object_class, PROP_PREV_POSITION,
+                                   g_param_spec_int ("prev-position", NULL, NULL,
+                                                     0, G_MAXINT, 0,
+                                                     GIMP_PARAM_READWRITE |
+                                                     G_PARAM_CONSTRUCT_ONLY));
+
+  g_object_class_install_property (object_class, PROP_PREV_LAYER,
+                                   g_param_spec_object ("prev-layer", NULL, NULL,
+                                                        GIMP_TYPE_LAYER,
+                                                        GIMP_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT_ONLY));
+}
+
+static void
+gimp_layer_undo_init (GimpLayerUndo *undo)
+{
+}
+
+static void
+gimp_layer_undo_constructed (GObject *object)
+{
+  G_OBJECT_CLASS (parent_class)->constructed (object);
+
+  gimp_assert (GIMP_IS_LAYER (GIMP_ITEM_UNDO (object)->item));
+}
+
+static void
+gimp_layer_undo_set_property (GObject      *object,
+                              guint         property_id,
+                              const GValue *value,
+                              GParamSpec   *pspec)
+{
+  GimpLayerUndo *layer_undo = GIMP_LAYER_UNDO (object);
+
+  switch (property_id)
+    {
+    case PROP_PREV_PARENT:
+      layer_undo->prev_parent = g_value_get_object (value);
+      break;
+    case PROP_PREV_POSITION:
+      layer_undo->prev_position = g_value_get_int (value);
+      break;
+    case PROP_PREV_LAYER:
+      layer_undo->prev_layer = g_value_get_object (value);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_layer_undo_get_property (GObject    *object,
+                              guint       property_id,
+                              GValue     *value,
+                              GParamSpec *pspec)
+{
+  GimpLayerUndo *layer_undo = GIMP_LAYER_UNDO (object);
+
+  switch (property_id)
+    {
+    case PROP_PREV_PARENT:
+      g_value_set_object (value, layer_undo->prev_parent);
+      break;
+    case PROP_PREV_POSITION:
+      g_value_set_int (value, layer_undo->prev_position);
+      break;
+    case PROP_PREV_LAYER:
+      g_value_set_object (value, layer_undo->prev_layer);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static gint64
+gimp_layer_undo_get_memsize (GimpObject *object,
+                             gint64     *gui_size)
+{
+  GimpItemUndo *item_undo = GIMP_ITEM_UNDO (object);
+  gint64        memsize   = 0;
+
+  if (! gimp_item_is_attached (item_undo->item))
+    memsize += gimp_object_get_memsize (GIMP_OBJECT (item_undo->item),
+                                        gui_size);
+
+  return memsize + GIMP_OBJECT_CLASS (parent_class)->get_memsize (object,
+                                                                  gui_size);
+}
+
+static void
+gimp_layer_undo_pop (GimpUndo            *undo,
+                     GimpUndoMode         undo_mode,
+                     GimpUndoAccumulator *accum)
+{
+  GimpLayerUndo *layer_undo = GIMP_LAYER_UNDO (undo);
+  GimpLayer     *layer      = GIMP_LAYER (GIMP_ITEM_UNDO (undo)->item);
+
+  GIMP_UNDO_CLASS (parent_class)->pop (undo, undo_mode, accum);
+
+  if ((undo_mode       == GIMP_UNDO_MODE_UNDO &&
+       undo->undo_type == GIMP_UNDO_LAYER_ADD) ||
+      (undo_mode       == GIMP_UNDO_MODE_REDO &&
+       undo->undo_type == GIMP_UNDO_LAYER_REMOVE))
+    {
+      /*  remove layer  */
+
+      /*  record the current parent and position  */
+      layer_undo->prev_parent   = gimp_layer_get_parent (layer);
+      layer_undo->prev_position = gimp_item_get_index (GIMP_ITEM (layer));
+
+      gimp_image_remove_layer (undo->image, layer, FALSE,
+                               layer_undo->prev_layer);
+    }
+  else
+    {
+      /*  restore layer  */
+
+      /*  record the active layer  */
+      layer_undo->prev_layer = gimp_image_get_active_layer (undo->image);
+
+      gimp_image_add_layer (undo->image, layer,
+                            layer_undo->prev_parent,
+                            layer_undo->prev_position, FALSE);
+    }
+}
diff --git a/app/core/gimplayerundo.h b/app/core/gimplayerundo.h
new file mode 100644
index 0000000..700fce8
--- /dev/null
+++ b/app/core/gimplayerundo.h
@@ -0,0 +1,54 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_LAYER_UNDO_H__
+#define __GIMP_LAYER_UNDO_H__
+
+
+#include "gimpitemundo.h"
+
+
+#define GIMP_TYPE_LAYER_UNDO            (gimp_layer_undo_get_type ())
+#define GIMP_LAYER_UNDO(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_LAYER_UNDO, GimpLayerUndo))
+#define GIMP_LAYER_UNDO_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_LAYER_UNDO, GimpLayerUndoClass))
+#define GIMP_IS_LAYER_UNDO(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_LAYER_UNDO))
+#define GIMP_IS_LAYER_UNDO_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_LAYER_UNDO))
+#define GIMP_LAYER_UNDO_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_LAYER_UNDO, GimpLayerUndoClass))
+
+
+typedef struct _GimpLayerUndo      GimpLayerUndo;
+typedef struct _GimpLayerUndoClass GimpLayerUndoClass;
+
+struct _GimpLayerUndo
+{
+  GimpItemUndo  parent_instance;
+
+  GimpLayer    *prev_parent;
+  gint          prev_position;   /*  former position in list  */
+  GimpLayer    *prev_layer;      /*  previous active layer    */
+};
+
+struct _GimpLayerUndoClass
+{
+  GimpItemUndoClass  parent_class;
+};
+
+
+GType   gimp_layer_undo_get_type (void) G_GNUC_CONST;
+
+
+#endif /* __GIMP_LAYER_UNDO_H__ */
diff --git a/app/core/gimplineart.c b/app/core/gimplineart.c
new file mode 100644
index 0000000..bf8460c
--- /dev/null
+++ b/app/core/gimplineart.c
@@ -0,0 +1,2979 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * Copyright (C) 2017 Sébastien Fourey & David Tchumperlé
+ * Copyright (C) 2018 Jehan
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpmath/gimpmath.h"
+
+#include "core-types.h"
+
+#include "gegl/gimp-gegl-loops.h"
+#include "gegl/gimp-gegl-utils.h"
+
+#include "gimp-parallel.h"
+#include "gimp-priorities.h"
+#include "gimp-utils.h" /* GIMP_TIMER */
+#include "gimpasync.h"
+#include "gimpcancelable.h"
+#include "gimpdrawable.h"
+#include "gimpimage.h"
+#include "gimplineart.h"
+#include "gimpmarshal.h"
+#include "gimppickable.h"
+#include "gimpprojection.h"
+#include "gimpviewable.h"
+#include "gimpwaitable.h"
+
+#include "gimp-intl.h"
+
+enum
+{
+  COMPUTING_START,
+  COMPUTING_END,
+  LAST_SIGNAL,
+};
+
+enum
+{
+  PROP_0,
+  PROP_SELECT_TRANSPARENT,
+  PROP_MAX_GROW,
+  PROP_THRESHOLD,
+  PROP_SPLINE_MAX_LEN,
+  PROP_SEGMENT_MAX_LEN,
+};
+
+typedef struct _GimpLineArtPrivate GimpLineArtPrivate;
+
+struct _GimpLineArtPrivate
+{
+  gboolean      frozen;
+  gboolean      compute_after_thaw;
+
+  GimpAsync    *async;
+
+  gint          idle_id;
+
+  GimpPickable *input;
+  GeglBuffer   *closed;
+  gfloat       *distmap;
+
+  /* Used in the closing step. */
+  gboolean      select_transparent;
+  gdouble       threshold;
+  gint          spline_max_len;
+  gint          segment_max_len;
+  gboolean      max_len_bound;
+
+  /* Used in the grow step. */
+  gint          max_grow;
+};
+
+typedef struct
+{
+  GeglBuffer  *buffer;
+
+  gboolean     select_transparent;
+  gdouble      threshold;
+  gint         spline_max_len;
+  gint         segment_max_len;
+} LineArtData;
+
+typedef struct
+{
+  GeglBuffer *closed;
+  gfloat     *distmap;
+} LineArtResult;
+
+static int DeltaX[4] = {+1, -1, 0, 0};
+static int DeltaY[4] = {0, 0, +1, -1};
+
+static const GimpVector2 Direction2Normal[4] =
+{
+    {  1.0f,  0.0f },
+    { -1.0f,  0.0f },
+    {  0.0f,  1.0f },
+    {  0.0f, -1.0f }
+};
+
+typedef enum _Direction
+{
+  XPlusDirection  = 0,
+  XMinusDirection = 1,
+  YPlusDirection  = 2,
+  YMinusDirection = 3
+} Direction;
+
+typedef GimpVector2 Pixel;
+
+typedef struct _SplineCandidate
+{
+  Pixel p1;
+  Pixel p2;
+  float quality;
+} SplineCandidate;
+
+typedef struct _Edgel
+{
+  gint      x, y;
+  Direction direction;
+
+  gfloat    x_normal;
+  gfloat    y_normal;
+  gfloat    curvature;
+  guint     next, previous;
+} Edgel;
+
+
+static void            gimp_line_art_finalize                  (GObject               *object);
+static void            gimp_line_art_set_property              (GObject                *object,
+                                                                guint                   property_id,
+                                                                const GValue           *value,
+                                                                GParamSpec             *pspec);
+static void            gimp_line_art_get_property              (GObject                *object,
+                                                                guint                   property_id,
+                                                                GValue                 *value,
+                                                                GParamSpec             *pspec);
+
+/* Functions for asynchronous computation. */
+
+static void            gimp_line_art_compute                   (GimpLineArt            *line_art);
+static void            gimp_line_art_compute_cb                (GimpAsync              *async,
+                                                                GimpLineArt            *line_art);
+
+static GimpAsync     * gimp_line_art_prepare_async             (GimpLineArt            *line_art,
+                                                                gint                    priority);
+static void            gimp_line_art_prepare_async_func        (GimpAsync              *async,
+                                                                LineArtData            *data);
+static LineArtData   * line_art_data_new                       (GeglBuffer             *buffer,
+                                                                GimpLineArt            *line_art);
+static void            line_art_data_free                      (LineArtData            *data);
+static LineArtResult * line_art_result_new                     (GeglBuffer             *line_art,
+                                                                gfloat                 *distmap);
+static void            line_art_result_free                    (LineArtResult          *result);
+
+static gboolean        gimp_line_art_idle                      (GimpLineArt            *line_art);
+static void            gimp_line_art_input_invalidate_preview  (GimpViewable           *viewable,
+                                                                GimpLineArt            *line_art);
+
+
+/* All actual computation functions. */
+
+static GeglBuffer    * gimp_line_art_close                     (GeglBuffer             *buffer,
+                                                                gboolean                select_transparent,
+                                                                gdouble                 stroke_threshold,
+                                                                gint                    spline_max_length,
+                                                                gint                    segment_max_length,
+                                                                gint                    minimal_lineart_area,
+                                                                gint                    normal_estimate_mask_size,
+                                                                gfloat                  end_point_rate,
+                                                                gfloat                  spline_max_angle,
+                                                                gint                    end_point_connectivity,
+                                                                gfloat                  spline_roundness,
+                                                                gboolean                allow_self_intersections,
+                                                                gint                    created_regions_significant_area,
+                                                                gint                    created_regions_minimum_area,
+                                                                gboolean                small_segments_from_spline_sources,
+                                                                gfloat                **lineart_distmap,
+                                                                GimpAsync              *async);
+
+static void            gimp_lineart_denoise                    (GeglBuffer             *buffer,
+                                                                int                     size,
+                                                                GimpAsync              *async);
+static void            gimp_lineart_compute_normals_curvatures (GeglBuffer             *mask,
+                                                                gfloat                 *normals,
+                                                                gfloat                 *curvatures,
+                                                                gfloat                 *smoothed_curvatures,
+                                                                int                     normal_estimate_mask_size,
+                                                                GimpAsync              *async);
+static gfloat        * gimp_lineart_get_smooth_curvatures      (GArray                 *edgelset,
+                                                                GimpAsync              *async);
+static GArray        * gimp_lineart_curvature_extremums        (gfloat                 *curvatures,
+                                                                gfloat                 *smoothed_curvatures,
+                                                                gint                    curvatures_width,
+                                                                gint                    curvatures_height,
+                                                                GimpAsync              *async);
+static gint            gimp_spline_candidate_cmp               (const SplineCandidate  *a,
+                                                                const SplineCandidate  *b,
+                                                                gpointer                user_data);
+static GList         * gimp_lineart_find_spline_candidates     (GArray                 *max_positions,
+                                                                gfloat                 *normals,
+                                                                gint                    width,
+                                                                gint                    distance_threshold,
+                                                                gfloat                  max_angle_deg,
+                                                                GimpAsync              *async);
+
+static GArray        * gimp_lineart_discrete_spline            (Pixel                   p0,
+                                                                GimpVector2             n0,
+                                                                Pixel                   p1,
+                                                                GimpVector2             n1);
+
+static gint            gimp_number_of_transitions               (GArray                 *pixels,
+                                                                 GeglBuffer             *buffer);
+static gboolean        gimp_line_art_allow_closure              (GeglBuffer             *mask,
+                                                                 GArray                 *pixels,
+                                                                 GList                 **fill_pixels,
+                                                                 int                     significant_size,
+                                                                 int                     minimum_size);
+static GArray        * gimp_lineart_line_segment_until_hit      (const GeglBuffer       *buffer,
+                                                                 Pixel                   start,
+                                                                 GimpVector2             direction,
+                                                                 int                     size);
+static gfloat        * gimp_lineart_estimate_strokes_radii      (GeglBuffer             *mask,
+                                                                 GimpAsync              *async);
+static void            gimp_line_art_simple_fill                (GeglBuffer             *buffer,
+                                                                 gint                    x,
+                                                                 gint                    y,
+                                                                 gint                   *counter);
+
+/* Some callback-type functions. */
+
+static guint           visited_hash_fun                         (Pixel                  *key);
+static gboolean        visited_equal_fun                        (Pixel                  *e1,
+                                                                 Pixel                  *e2);
+
+static inline gboolean border_in_direction                      (GeglBuffer             *mask,
+                                                                 Pixel                   p,
+                                                                 int                     direction);
+static inline GimpVector2 pair2normal                           (Pixel                   p,
+                                                                 gfloat                 *normals,
+                                                                 gint                    width);
+
+/* Edgel */
+
+static Edgel    * gimp_edgel_new                  (int                x,
+                                                   int                y,
+                                                   Direction          direction);
+static void       gimp_edgel_init                 (Edgel             *edgel);
+static void       gimp_edgel_clear                (Edgel            **edgel);
+static int        gimp_edgel_cmp                  (const Edgel       *e1,
+                                                   const Edgel       *e2);
+static guint      edgel2index_hash_fun            (Edgel              *key);
+static gboolean   edgel2index_equal_fun           (Edgel              *e1,
+                                                   Edgel              *e2);
+
+static glong      gimp_edgel_track_mark           (GeglBuffer         *mask,
+                                                   Edgel               edgel,
+                                                   long                size_limit);
+static glong      gimp_edgel_region_area          (const GeglBuffer   *mask,
+                                                   Edgel               start_edgel);
+
+/* Edgel set */
+
+static GArray   * gimp_edgelset_new               (GeglBuffer         *buffer,
+                                                   GimpAsync          *async);
+static void       gimp_edgelset_add               (GArray             *set,
+                                                   int                 x,
+                                                   int                 y,
+                                                   Direction           direction,
+                                                   GHashTable         *edgel2index);
+static void       gimp_edgelset_init_normals      (GArray             *set);
+static void       gimp_edgelset_smooth_normals    (GArray             *set,
+                                                   int                 mask_size,
+                                                   GimpAsync          *async);
+static void       gimp_edgelset_compute_curvature (GArray             *set,
+                                                   GimpAsync          *async);
+
+static void       gimp_edgelset_build_graph       (GArray            *set,
+                                                   GeglBuffer        *buffer,
+                                                   GHashTable        *edgel2index,
+                                                   GimpAsync         *async);
+static void       gimp_edgelset_next8             (const GeglBuffer  *buffer,
+                                                   Edgel             *it,
+                                                   Edgel             *n);
+
+G_DEFINE_TYPE_WITH_CODE (GimpLineArt, gimp_line_art, GIMP_TYPE_OBJECT,
+                         G_ADD_PRIVATE (GimpLineArt))
+
+static guint gimp_line_art_signals[LAST_SIGNAL] = { 0 };
+
+static void
+gimp_line_art_class_init (GimpLineArtClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  gimp_line_art_signals[COMPUTING_START] =
+    g_signal_new ("computing-start",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpLineArtClass, computing_start),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+  gimp_line_art_signals[COMPUTING_END] =
+    g_signal_new ("computing-end",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpLineArtClass, computing_end),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  object_class->finalize     = gimp_line_art_finalize;
+  object_class->set_property = gimp_line_art_set_property;
+  object_class->get_property = gimp_line_art_get_property;
+
+  g_object_class_install_property (object_class, PROP_SELECT_TRANSPARENT,
+                                   g_param_spec_boolean ("select-transparent",
+                                                         _("Select transparent pixels instead of gray ones"),
+                                                         _("Select transparent pixels instead of gray ones"),
+                                                         TRUE,
+                                                         G_PARAM_CONSTRUCT | GIMP_PARAM_READWRITE));
+
+  g_object_class_install_property (object_class, PROP_THRESHOLD,
+                                   g_param_spec_double ("threshold",
+                                                        _("Line art detection threshold"),
+                                                        _("Threshold to detect contour (higher values will include more pixels)"),
+                                                        0.0, 1.0, 0.92,
+                                                        G_PARAM_CONSTRUCT | GIMP_PARAM_READWRITE));
+
+  g_object_class_install_property (object_class, PROP_MAX_GROW,
+                                   g_param_spec_int ("max-grow",
+                                                     _("Maximum growing size"),
+                                                     _("Maximum number of pixels grown under the line art"),
+                                                     1, 100, 3,
+                                                     G_PARAM_CONSTRUCT | GIMP_PARAM_READWRITE));
+
+  g_object_class_install_property (object_class, PROP_SPLINE_MAX_LEN,
+                                   g_param_spec_int ("spline-max-length",
+                                                     _("Maximum curved closing length"),
+                                                     _("Maximum curved length (in pixels) to close the line art"),
+                                                     0, 1000, 100,
+                                                     G_PARAM_CONSTRUCT | GIMP_PARAM_READWRITE));
+
+  g_object_class_install_property (object_class, PROP_SEGMENT_MAX_LEN,
+                                   g_param_spec_int ("segment-max-length",
+                                                     _("Maximum straight closing length"),
+                                                     _("Maximum straight length (in pixels) to close the line art"),
+                                                     0, 1000, 100,
+                                                     G_PARAM_CONSTRUCT | GIMP_PARAM_READWRITE));
+}
+
+static void
+gimp_line_art_init (GimpLineArt *line_art)
+{
+  line_art->priv = gimp_line_art_get_instance_private (line_art);
+}
+
+static void
+gimp_line_art_finalize (GObject *object)
+{
+  GimpLineArt *line_art = GIMP_LINE_ART (object);
+
+  line_art->priv->frozen = FALSE;
+
+  gimp_line_art_set_input (line_art, NULL);
+}
+
+static void
+gimp_line_art_set_property (GObject      *object,
+                            guint         property_id,
+                            const GValue *value,
+                            GParamSpec   *pspec)
+{
+  GimpLineArt *line_art = GIMP_LINE_ART (object);
+
+  switch (property_id)
+    {
+    case PROP_SELECT_TRANSPARENT:
+      if (line_art->priv->select_transparent != g_value_get_boolean (value))
+        {
+          line_art->priv->select_transparent = g_value_get_boolean (value);
+          gimp_line_art_compute (line_art);
+        }
+      break;
+    case PROP_MAX_GROW:
+      line_art->priv->max_grow = g_value_get_int (value);
+      break;
+    case PROP_THRESHOLD:
+      if (line_art->priv->threshold != g_value_get_double (value))
+        {
+          line_art->priv->threshold = g_value_get_double (value);
+          gimp_line_art_compute (line_art);
+        }
+      break;
+    case PROP_SPLINE_MAX_LEN:
+      if (line_art->priv->spline_max_len != g_value_get_int (value))
+        {
+          line_art->priv->spline_max_len = g_value_get_int (value);
+          if (line_art->priv->max_len_bound)
+            line_art->priv->segment_max_len = line_art->priv->spline_max_len;
+          gimp_line_art_compute (line_art);
+        }
+      break;
+    case PROP_SEGMENT_MAX_LEN:
+      if (line_art->priv->segment_max_len != g_value_get_int (value))
+        {
+          line_art->priv->segment_max_len = g_value_get_int (value);
+          if (line_art->priv->max_len_bound)
+            line_art->priv->spline_max_len = line_art->priv->segment_max_len;
+          gimp_line_art_compute (line_art);
+        }
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_line_art_get_property (GObject    *object,
+                            guint       property_id,
+                            GValue     *value,
+                            GParamSpec *pspec)
+{
+  GimpLineArt *line_art = GIMP_LINE_ART (object);
+
+  switch (property_id)
+    {
+    case PROP_SELECT_TRANSPARENT:
+      g_value_set_boolean (value, line_art->priv->select_transparent);
+      break;
+    case PROP_MAX_GROW:
+      g_value_set_int (value, line_art->priv->max_grow);
+      break;
+    case PROP_THRESHOLD:
+      g_value_set_double (value, line_art->priv->threshold);
+      break;
+    case PROP_SPLINE_MAX_LEN:
+      g_value_set_int (value, line_art->priv->spline_max_len);
+      break;
+    case PROP_SEGMENT_MAX_LEN:
+      g_value_set_int (value, line_art->priv->segment_max_len);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+/* Public functions */
+
+GimpLineArt *
+gimp_line_art_new (void)
+{
+  return g_object_new (GIMP_TYPE_LINE_ART,
+                       NULL);
+}
+
+void
+gimp_line_art_bind_gap_length (GimpLineArt *line_art,
+                               gboolean     bound)
+{
+  line_art->priv->max_len_bound = bound;
+}
+
+void
+gimp_line_art_set_input (GimpLineArt  *line_art,
+                         GimpPickable *pickable)
+{
+  g_return_if_fail (pickable == NULL || GIMP_IS_VIEWABLE (pickable));
+
+  if (pickable != line_art->priv->input)
+    {
+      if (line_art->priv->input)
+        g_signal_handlers_disconnect_by_data (line_art->priv->input, line_art);
+
+      g_set_object (&line_art->priv->input, pickable);
+
+      gimp_line_art_compute (line_art);
+
+      if (pickable)
+        {
+          g_signal_connect (pickable, "invalidate-preview",
+                            G_CALLBACK (gimp_line_art_input_invalidate_preview),
+                            line_art);
+        }
+    }
+}
+
+GimpPickable *
+gimp_line_art_get_input (GimpLineArt *line_art)
+{
+  return line_art->priv->input;
+}
+
+void
+gimp_line_art_freeze (GimpLineArt *line_art)
+{
+  g_return_if_fail (! line_art->priv->frozen);
+
+  line_art->priv->frozen             = TRUE;
+  line_art->priv->compute_after_thaw = FALSE;
+}
+
+void
+gimp_line_art_thaw (GimpLineArt *line_art)
+{
+  g_return_if_fail (line_art->priv->frozen);
+
+  line_art->priv->frozen = FALSE;
+  if (line_art->priv->compute_after_thaw)
+    {
+      gimp_line_art_compute (line_art);
+      line_art->priv->compute_after_thaw = FALSE;
+    }
+}
+
+gboolean
+gimp_line_art_is_frozen (GimpLineArt *line_art)
+{
+  return line_art->priv->frozen;
+}
+
+GeglBuffer *
+gimp_line_art_get (GimpLineArt  *line_art,
+                   gfloat      **distmap)
+{
+  g_return_val_if_fail (line_art->priv->input, NULL);
+
+  if (line_art->priv->async)
+    {
+      gimp_waitable_wait (GIMP_WAITABLE (line_art->priv->async));
+    }
+  else if (! line_art->priv->closed)
+    {
+      gimp_line_art_compute (line_art);
+      if (line_art->priv->async)
+        gimp_waitable_wait (GIMP_WAITABLE (line_art->priv->async));
+    }
+
+  g_return_val_if_fail (line_art->priv->closed, NULL);
+
+  if (distmap)
+    *distmap = line_art->priv->distmap;
+
+  return line_art->priv->closed;
+}
+
+/* Functions for asynchronous computation. */
+
+static void
+gimp_line_art_compute (GimpLineArt *line_art)
+{
+  if (line_art->priv->frozen)
+    {
+      line_art->priv->compute_after_thaw = TRUE;
+      return;
+    }
+
+  if (line_art->priv->async)
+    {
+      /* we cancel the async, but don't wait for it to finish, since
+       * it might take a while to respond.  instead gimp_line_art_compute_cb()
+       * bails if the async has been canceled, to avoid accessing the line art.
+       */
+      g_signal_emit (line_art, gimp_line_art_signals[COMPUTING_END], 0);
+      gimp_cancelable_cancel (GIMP_CANCELABLE (line_art->priv->async));
+      g_clear_object (&line_art->priv->async);
+    }
+
+  if (line_art->priv->idle_id)
+    {
+      g_source_remove (line_art->priv->idle_id);
+      line_art->priv->idle_id = 0;
+    }
+
+  g_clear_object (&line_art->priv->closed);
+  g_clear_pointer (&line_art->priv->distmap, g_free);
+
+  if (line_art->priv->input)
+    {
+      /* gimp_line_art_prepare_async() will flush the pickable, which
+       * may trigger this signal handler, and will leak a line art (as
+       * line_art->priv->async has not been set yet).
+       */
+      g_signal_handlers_block_by_func (
+        line_art->priv->input,
+        G_CALLBACK (gimp_line_art_input_invalidate_preview),
+        line_art);
+      line_art->priv->async = gimp_line_art_prepare_async (line_art, +1);
+      g_signal_emit (line_art, gimp_line_art_signals[COMPUTING_START], 0);
+      g_signal_handlers_unblock_by_func (
+        line_art->priv->input,
+        G_CALLBACK (gimp_line_art_input_invalidate_preview),
+        line_art);
+
+      gimp_async_add_callback_for_object (line_art->priv->async,
+                                          (GimpAsyncCallback) gimp_line_art_compute_cb,
+                                          line_art, line_art);
+    }
+}
+
+static void
+gimp_line_art_compute_cb (GimpAsync   *async,
+                          GimpLineArt *line_art)
+{
+  if (gimp_async_is_canceled (async))
+    return;
+
+  if (gimp_async_is_finished (async))
+    {
+      LineArtResult *result;
+
+      result = gimp_async_get_result (async);
+
+      line_art->priv->closed  = g_object_ref (result->closed);
+      line_art->priv->distmap = result->distmap;
+      result->distmap  = NULL;
+      g_signal_emit (line_art, gimp_line_art_signals[COMPUTING_END], 0);
+    }
+
+  g_clear_object (&line_art->priv->async);
+}
+
+static GimpAsync *
+gimp_line_art_prepare_async (GimpLineArt *line_art,
+                             gint         priority)
+{
+  GeglBuffer  *buffer;
+  GimpAsync   *async;
+  LineArtData *data;
+
+  g_return_val_if_fail (GIMP_IS_PICKABLE (line_art->priv->input), NULL);
+
+  gimp_pickable_flush (line_art->priv->input);
+
+  buffer = gimp_gegl_buffer_dup (
+    gimp_pickable_get_buffer (line_art->priv->input));
+
+  data  = line_art_data_new (buffer, line_art);
+
+  g_object_unref (buffer);
+
+  async = gimp_parallel_run_async_full (
+    priority,
+    (GimpRunAsyncFunc) gimp_line_art_prepare_async_func,
+    data, (GDestroyNotify) line_art_data_free);
+
+  return async;
+}
+
+static void
+gimp_line_art_prepare_async_func (GimpAsync   *async,
+                                  LineArtData *data)
+{
+  GeglBuffer *buffer;
+  GeglBuffer *closed  = NULL;
+  gfloat     *distmap = NULL;
+  gint        buffer_x;
+  gint        buffer_y;
+  gboolean    has_alpha;
+  gboolean    select_transparent = FALSE;
+
+  has_alpha = babl_format_has_alpha (gegl_buffer_get_format (data->buffer));
+
+  if (has_alpha)
+    {
+      if (data->select_transparent)
+        {
+          /*  don't select transparent regions if there are no fully
+           *  transparent pixels.
+           */
+          GeglBufferIterator *gi;
+
+          gi = gegl_buffer_iterator_new (data->buffer, NULL, 0,
+                                         babl_format ("A u8"),
+                                         GEGL_ACCESS_READ, GEGL_ABYSS_NONE, 3);
+          while (gegl_buffer_iterator_next (gi))
+            {
+              guint8 *p = (guint8*) gi->items[0].data;
+              gint    k;
+
+              if (gimp_async_is_canceled (async))
+                {
+                  gegl_buffer_iterator_stop (gi);
+
+                  gimp_async_abort (async);
+
+                  line_art_data_free (data);
+
+                  return;
+                }
+
+              for (k = 0; k < gi->length; k++)
+                {
+                  if (! *p)
+                    {
+                      select_transparent = TRUE;
+                      break;
+                    }
+                  p++;
+                }
+              if (select_transparent)
+                break;
+            }
+          if (select_transparent)
+            gegl_buffer_iterator_stop (gi);
+        }
+    }
+
+  buffer   = data->buffer;
+  buffer_x = gegl_buffer_get_x (data->buffer);
+  buffer_y = gegl_buffer_get_y (data->buffer);
+
+  if (buffer_x != 0 || buffer_y != 0)
+    {
+      buffer = g_object_new (GEGL_TYPE_BUFFER,
+                             "source",  buffer,
+                             "shift-x", buffer_x,
+                             "shift-y", buffer_y,
+                             NULL);
+    }
+
+  /* For smart selection, we generate a binarized image with close
+   * regions, then run a composite selection with no threshold on
+   * this intermediate buffer.
+   */
+  GIMP_TIMER_START();
+
+  closed = gimp_line_art_close (buffer,
+                                select_transparent,
+                                data->threshold,
+                                data->spline_max_len,
+                                data->segment_max_len,
+                                /*minimal_lineart_area,*/
+                                5,
+                                /*normal_estimate_mask_size,*/
+                                5,
+                                /*end_point_rate,*/
+                                0.85,
+                                /*spline_max_angle,*/
+                                90.0,
+                                /*end_point_connectivity,*/
+                                2,
+                                /*spline_roundness,*/
+                                1.0,
+                                /*allow_self_intersections,*/
+                                TRUE,
+                                /*created_regions_significant_area,*/
+                                4,
+                                /*created_regions_minimum_area,*/
+                                100,
+                                /*small_segments_from_spline_sources,*/
+                                TRUE,
+                                &distmap,
+                                async);
+
+  GIMP_TIMER_END("close line-art");
+
+  if (buffer != data->buffer)
+    g_object_unref (buffer);
+
+  if (! gimp_async_is_stopped (async))
+    {
+      if (buffer_x != 0 || buffer_y != 0)
+        {
+          buffer = g_object_new (GEGL_TYPE_BUFFER,
+                                 "source",  closed,
+                                 "shift-x", -buffer_x,
+                                 "shift-y", -buffer_y,
+                                 NULL);
+
+          g_object_unref (closed);
+
+          closed = buffer;
+        }
+
+      gimp_async_finish_full (async,
+                              line_art_result_new (closed, distmap),
+                              (GDestroyNotify) line_art_result_free);
+    }
+
+  line_art_data_free (data);
+}
+
+static LineArtData *
+line_art_data_new (GeglBuffer  *buffer,
+                   GimpLineArt *line_art)
+{
+  LineArtData *data = g_slice_new (LineArtData);
+
+  data->buffer             = g_object_ref (buffer);
+  data->select_transparent = line_art->priv->select_transparent;
+  data->threshold          = line_art->priv->threshold;
+  data->spline_max_len     = line_art->priv->spline_max_len;
+  data->segment_max_len    = line_art->priv->segment_max_len;
+
+  return data;
+}
+
+static void
+line_art_data_free (LineArtData *data)
+{
+  g_object_unref (data->buffer);
+
+  g_slice_free (LineArtData, data);
+}
+
+static LineArtResult *
+line_art_result_new (GeglBuffer *closed,
+                     gfloat     *distmap)
+{
+  LineArtResult *data;
+
+  data = g_slice_new (LineArtResult);
+  data->closed  = closed;
+  data->distmap = distmap;
+
+  return data;
+}
+
+static void
+line_art_result_free (LineArtResult *data)
+{
+  g_object_unref (data->closed);
+  g_clear_pointer (&data->distmap, g_free);
+
+  g_slice_free (LineArtResult, data);
+}
+
+static gboolean
+gimp_line_art_idle (GimpLineArt *line_art)
+{
+  line_art->priv->idle_id = 0;
+
+  gimp_line_art_compute (line_art);
+
+  return G_SOURCE_REMOVE;
+}
+
+static void
+gimp_line_art_input_invalidate_preview (GimpViewable *viewable,
+                                        GimpLineArt  *line_art)
+{
+  if (! line_art->priv->idle_id)
+    {
+      line_art->priv->idle_id = g_idle_add_full (
+        GIMP_PRIORITY_VIEWABLE_IDLE,
+        (GSourceFunc) gimp_line_art_idle,
+        line_art, NULL);
+    }
+}
+
+/* All actual computation functions. */
+
+/**
+ * gimp_line_art_close:
+ * @buffer: the input #GeglBuffer.
+ * @select_transparent: whether we binarize the alpha channel or the
+ *                      luminosity.
+ * @stroke_threshold: [0-1] threshold value for detecting stroke pixels
+ *                    (higher values will detect more stroke pixels).
+ * @spline_max_length: the maximum length for creating splines between
+ *                     end points.
+ * @segment_max_length: the maximum length for creating segments
+ *                      between end points. Unlike splines, segments
+ *                      are straight lines.
+ * @minimal_lineart_area: the minimum size in number pixels for area to
+ *                        be considered as line art.
+ * @normal_estimate_mask_size:
+ * @end_point_rate: threshold to estimate if a curvature is an end-point
+ *                  in [0-1] range value.
+ * @spline_max_angle: the maximum angle between end point normals for
+ *                    creating splines between them.
+ * @end_point_connectivity:
+ * @spline_roundness:
+ * @allow_self_intersections: whether to allow created splines and
+ *                            segments to intersect.
+ * @created_regions_significant_area:
+ * @created_regions_minimum_area:
+ * @small_segments_from_spline_sources:
+ * @closed_distmap: a distance map of the closed line art pixels.
+ * @async: the #GimpAsync associated with the computation
+ *
+ * Creates a binarized version of the strokes of @buffer, detected either
+ * with luminosity (light means background) or alpha values depending on
+ * @select_transparent. This binary version of the strokes will have closed
+ * regions allowing adequate selection of "nearly closed regions".
+ * This algorithm is meant for digital painting (and in particular on the
+ * sketch-only step), and therefore will likely produce unexpected results on
+ * other types of input.
+ *
+ * The algorithm is the first step from the research paper "A Fast and
+ * Efficient Semi-guided Algorithm for Flat Coloring Line-arts", by Sébastian
+ * Fourey, David Tschumperlé, David Revoy.
+ * https://hal.archives-ouvertes.fr/hal-01891876
+ *
+ * Returns: a new #GeglBuffer of format "Y u8" representing the
+ *          binarized @line_art. If @lineart_distmap is not #NULL, a
+ *          newly allocated float buffer is returned, which can be used
+ *          for overflowing created masks later.
+ */
+static GeglBuffer *
+gimp_line_art_close (GeglBuffer  *buffer,
+                     gboolean     select_transparent,
+                     gdouble      stroke_threshold,
+                     gint         spline_max_length,
+                     gint         segment_max_length,
+                     gint         minimal_lineart_area,
+                     gint         normal_estimate_mask_size,
+                     gfloat       end_point_rate,
+                     gfloat       spline_max_angle,
+                     gint         end_point_connectivity,
+                     gfloat       spline_roundness,
+                     gboolean     allow_self_intersections,
+                     gint         created_regions_significant_area,
+                     gint         created_regions_minimum_area,
+                     gboolean     small_segments_from_spline_sources,
+                     gfloat     **closed_distmap,
+                     GimpAsync   *async)
+{
+  const Babl         *gray_format;
+  GeglBufferIterator *gi;
+  GeglBuffer         *closed  = NULL;
+  GeglBuffer         *strokes = NULL;
+  guchar              max_value = 0;
+  gint                width  = gegl_buffer_get_width (buffer);
+  gint                height = gegl_buffer_get_height (buffer);
+  gint                i;
+
+  if (select_transparent)
+    /* Keep alpha channel as gray levels */
+    gray_format = babl_format ("A u8");
+  else
+    /* Keep luminance */
+    gray_format = babl_format ("Y' u8");
+
+  /* Transform the line art from any format to gray. */
+  strokes = gegl_buffer_new (gegl_buffer_get_extent (buffer),
+                             gray_format);
+  gimp_gegl_buffer_copy (buffer, NULL, GEGL_ABYSS_NONE, strokes, NULL);
+  gegl_buffer_set_format (strokes, babl_format ("Y' u8"));
+
+  if (! select_transparent)
+    {
+      /* Compute the biggest value */
+      gi = gegl_buffer_iterator_new (strokes, NULL, 0, NULL,
+                                     GEGL_ACCESS_READ, GEGL_ABYSS_NONE, 1);
+      while (gegl_buffer_iterator_next (gi))
+        {
+          guchar *data = (guchar*) gi->items[0].data;
+          gint    k;
+
+          if (gimp_async_is_canceled (async))
+            {
+              gegl_buffer_iterator_stop (gi);
+
+              gimp_async_abort (async);
+
+              goto end1;
+            }
+
+          for (k = 0; k < gi->length; k++)
+            {
+              if (*data > max_value)
+                max_value = *data;
+              data++;
+            }
+        }
+    }
+
+  /* Make the image binary: 1 is stroke, 0 background */
+  gi = gegl_buffer_iterator_new (strokes, NULL, 0, NULL,
+                                 GEGL_ACCESS_READWRITE, GEGL_ABYSS_NONE, 1);
+  while (gegl_buffer_iterator_next (gi))
+    {
+      guchar *data = (guchar*) gi->items[0].data;
+      gint    k;
+
+      if (gimp_async_is_canceled (async))
+        {
+          gegl_buffer_iterator_stop (gi);
+
+          gimp_async_abort (async);
+
+          goto end1;
+        }
+
+      for (k = 0; k < gi->length; k++)
+        {
+          if (! select_transparent)
+            /* Negate the value. */
+            *data = max_value - *data;
+          /* Apply a threshold. */
+          if (*data > (guchar) (255.0f * (1.0f - stroke_threshold)))
+            *data = 1;
+          else
+            *data = 0;
+          data++;
+        }
+    }
+
+  /* Denoise (remove small connected components) */
+  gimp_lineart_denoise (strokes, minimal_lineart_area, async);
+  if (gimp_async_is_stopped (async))
+    goto end1;
+
+  closed = g_object_ref (strokes);
+
+  if (spline_max_length > 0 || segment_max_length > 0)
+    {
+      GArray     *keypoints           = NULL;
+      GHashTable *visited             = NULL;
+      gfloat     *radii               = NULL;
+      gfloat     *normals             = NULL;
+      gfloat     *curvatures          = NULL;
+      gfloat     *smoothed_curvatures = NULL;
+      gfloat      threshold;
+      gfloat      clamped_threshold;
+      GList      *fill_pixels         = NULL;
+      GList      *iter;
+
+      normals             = g_new0 (gfloat, width * height * 2);
+      curvatures          = g_new0 (gfloat, width * height);
+      smoothed_curvatures = g_new0 (gfloat, width * height);
+
+      /* Estimate normals & curvature */
+      gimp_lineart_compute_normals_curvatures (strokes, normals, curvatures,
+                                               smoothed_curvatures,
+                                               normal_estimate_mask_size,
+                                               async);
+      if (gimp_async_is_stopped (async))
+        goto end2;
+
+      radii = gimp_lineart_estimate_strokes_radii (strokes, async);
+      if (gimp_async_is_stopped (async))
+        goto end2;
+      threshold = 1.0f - end_point_rate;
+      clamped_threshold = MAX (0.25f, threshold);
+      for (i = 0; i < width; i++)
+        {
+          gint j;
+
+          if (gimp_async_is_canceled (async))
+            {
+              gimp_async_abort (async);
+
+              goto end2;
+            }
+
+          for (j = 0; j < height; j++)
+            {
+              if (smoothed_curvatures[i + j * width] >= (threshold / MAX (1.0f, radii[i + j * width])) ||
+                  curvatures[i + j * width] >= clamped_threshold)
+                curvatures[i + j * width] = 1.0;
+              else
+                curvatures[i + j * width] = 0.0;
+            }
+        }
+      g_clear_pointer (&radii, g_free);
+
+      keypoints = gimp_lineart_curvature_extremums (curvatures, smoothed_curvatures,
+                                                    width, height, async);
+      if (gimp_async_is_stopped (async))
+        goto end2;
+
+      visited = g_hash_table_new_full ((GHashFunc) visited_hash_fun,
+                                       (GEqualFunc) visited_equal_fun,
+                                       (GDestroyNotify) g_free, NULL);
+
+      if (spline_max_length > 0)
+        {
+          GList           *candidates;
+          SplineCandidate *candidate;
+
+          candidates = gimp_lineart_find_spline_candidates (keypoints, normals, width,
+                                                            spline_max_length,
+                                                            spline_max_angle,
+                                                            async);
+          if (gimp_async_is_stopped (async))
+            goto end3;
+
+          g_object_unref (closed);
+          closed = gimp_gegl_buffer_dup (strokes);
+
+          /* Draw splines */
+          while (candidates)
+            {
+              Pixel    *p1;
+              Pixel    *p2;
+              gboolean  inserted = FALSE;
+
+              if (gimp_async_is_canceled (async))
+                {
+                  gimp_async_abort (async);
+
+                  goto end3;
+                }
+
+              p1 = g_new (Pixel, 1);
+              p2 = g_new (Pixel, 1);
+
+              candidate = (SplineCandidate *) candidates->data;
+              p1->x = candidate->p1.x;
+              p1->y = candidate->p1.y;
+              p2->x = candidate->p2.x;
+              p2->y = candidate->p2.y;
+
+              g_free (candidate);
+              candidates = g_list_delete_link (candidates, candidates);
+
+              if ((! g_hash_table_contains (visited, p1) ||
+                   GPOINTER_TO_INT (g_hash_table_lookup (visited, p1)) < end_point_connectivity) &&
+                  (! g_hash_table_contains (visited, p2) ||
+                   GPOINTER_TO_INT (g_hash_table_lookup (visited, p2)) < end_point_connectivity))
+                {
+                  GArray      *discrete_curve;
+                  GimpVector2  vect1 = pair2normal (*p1, normals, width);
+                  GimpVector2  vect2 = pair2normal (*p2, normals, width);
+                  gfloat       distance = gimp_vector2_length_val (gimp_vector2_sub_val (*p1, *p2));
+                  gint         transitions;
+
+                  gimp_vector2_mul (&vect1, distance);
+                  gimp_vector2_mul (&vect1, spline_roundness);
+                  gimp_vector2_mul (&vect2, distance);
+                  gimp_vector2_mul (&vect2, spline_roundness);
+
+                  discrete_curve = gimp_lineart_discrete_spline (*p1, vect1, *p2, vect2);
+
+                  transitions = allow_self_intersections ?
+                    gimp_number_of_transitions (discrete_curve, strokes) :
+                    gimp_number_of_transitions (discrete_curve, closed);
+
+                  if (transitions == 2 &&
+                      gimp_line_art_allow_closure (closed, discrete_curve,
+                                                   &fill_pixels,
+                                                   created_regions_significant_area,
+                                                   created_regions_minimum_area))
+                    {
+                      for (i = 0; i < discrete_curve->len; i++)
+                        {
+                          Pixel p = g_array_index (discrete_curve, Pixel, i);
+
+                          if (p.x >= 0 && p.x < gegl_buffer_get_width (closed) &&
+                              p.y >= 0 && p.y < gegl_buffer_get_height (closed))
+                            {
+                              guchar val = 2;
+
+                              gegl_buffer_set (closed, GEGL_RECTANGLE ((gint) p.x, (gint) p.y, 1, 1), 0,
+                                               NULL, &val, GEGL_AUTO_ROWSTRIDE);
+                            }
+                        }
+                      g_hash_table_replace (visited, p1,
+                                            GINT_TO_POINTER (GPOINTER_TO_INT (g_hash_table_lookup (visited, p1)) + 1));
+                      g_hash_table_replace (visited, p2,
+                                            GINT_TO_POINTER (GPOINTER_TO_INT (g_hash_table_lookup (visited, p2)) + 1));
+                      inserted = TRUE;
+                    }
+                  g_array_free (discrete_curve, TRUE);
+                }
+              if (! inserted)
+                {
+                  g_free (p1);
+                  g_free (p2);
+                }
+            }
+
+ end3:
+          g_list_free_full (candidates, g_free);
+
+          if (gimp_async_is_stopped (async))
+            goto end2;
+        }
+
+      g_clear_object (&strokes);
+
+      /* Draw straight line segments */
+      if (segment_max_length > 0)
+        {
+          Pixel *point;
+
+          point = (Pixel *) keypoints->data;
+          for (i = 0; i < keypoints->len; i++)
+            {
+              Pixel    *p;
+              gboolean  inserted = FALSE;
+
+              if (gimp_async_is_canceled (async))
+                {
+                  gimp_async_abort (async);
+
+                  goto end2;
+                }
+
+              p  = g_new (Pixel, 1);
+              *p = *point;
+
+              if (! g_hash_table_contains (visited, p) ||
+                  (small_segments_from_spline_sources &&
+                   GPOINTER_TO_INT (g_hash_table_lookup (visited, p)) < end_point_connectivity))
+                {
+                  GArray *segment = gimp_lineart_line_segment_until_hit (closed, *point,
+                                                                         pair2normal (*point, normals, width),
+                                                                         segment_max_length);
+
+                  if (segment->len &&
+                      gimp_line_art_allow_closure (closed, segment, &fill_pixels,
+                                                   created_regions_significant_area,
+                                                   created_regions_minimum_area))
+                    {
+                      gint j;
+
+                      for (j = 0; j < segment->len; j++)
+                        {
+                          Pixel  p2 = g_array_index (segment, Pixel, j);
+                          guchar val = 2;
+
+                          gegl_buffer_set (closed, GEGL_RECTANGLE ((gint) p2.x, (gint) p2.y, 1, 1), 0,
+                                           NULL, &val, GEGL_AUTO_ROWSTRIDE);
+                        }
+                      g_hash_table_replace (visited, p,
+                                            GINT_TO_POINTER (GPOINTER_TO_INT (g_hash_table_lookup (visited, p)) + 1));
+                      inserted = TRUE;
+                    }
+                  g_array_free (segment, TRUE);
+                }
+              if (! inserted)
+                g_free (p);
+              point++;
+            }
+        }
+
+      for (iter = fill_pixels; iter; iter = iter->next)
+        {
+          Pixel *p        = iter->data;
+          gint   fill_max = created_regions_significant_area - 1;
+
+          if (gimp_async_is_canceled (async))
+            {
+              gimp_async_abort (async);
+
+              goto end2;
+            }
+
+          /* XXX A best approach would be to generalize
+           * gimp_drawable_bucket_fill() to work on any buffer (the code
+           * is already mostly there) rather than reimplementing a naive
+           * bucket fill.
+           * This is mostly a quick'n dirty first implementation which I
+           * will improve later.
+           */
+          gimp_line_art_simple_fill (closed, (gint) p->x, (gint) p->y, &fill_max);
+        }
+
+ end2:
+      g_list_free_full (fill_pixels, g_free);
+      g_free (normals);
+      g_free (curvatures);
+      g_free (smoothed_curvatures);
+      g_clear_pointer (&radii, g_free);
+      if (keypoints)
+        g_array_free (keypoints, TRUE);
+      g_clear_pointer (&visited, g_hash_table_destroy);
+
+      if (gimp_async_is_stopped (async))
+        goto end1;
+    }
+  else
+    {
+      g_clear_object (&strokes);
+    }
+
+  if (closed_distmap)
+    {
+      GeglNode   *graph;
+      GeglNode   *input;
+      GeglNode   *op;
+
+      /* Flooding needs a distance map for closed line art. */
+      *closed_distmap = g_new (gfloat, width * height);
+
+      graph = gegl_node_new ();
+      input = gegl_node_new_child (graph,
+                                   "operation", "gegl:buffer-source",
+                                   "buffer", closed,
+                                   NULL);
+      op  = gegl_node_new_child (graph,
+                                 "operation", "gegl:distance-transform",
+                                 "metric",    GEGL_DISTANCE_METRIC_EUCLIDEAN,
+                                 "normalize", FALSE,
+                                 NULL);
+      gegl_node_connect_to (input, "output",
+                            op, "input");
+      gegl_node_blit (op, 1.0, gegl_buffer_get_extent (closed),
+                      NULL, *closed_distmap,
+                      GEGL_AUTO_ROWSTRIDE, GEGL_BLIT_DEFAULT);
+      g_object_unref (graph);
+    }
+
+ end1:
+  g_clear_object (&strokes);
+
+  if (gimp_async_is_stopped (async))
+    g_clear_object (&closed);
+
+  return closed;
+}
+
+static void
+gimp_lineart_denoise (GeglBuffer *buffer,
+                      int         minimum_area,
+                      GimpAsync  *async)
+{
+  /* Keep connected regions with significant area. */
+  GArray   *region;
+  GQueue   *q       = g_queue_new ();
+  gint      width   = gegl_buffer_get_width (buffer);
+  gint      height  = gegl_buffer_get_height (buffer);
+  gboolean *visited = g_new0 (gboolean, width * height);
+  gint      x, y;
+
+  region = g_array_sized_new (TRUE, TRUE, sizeof (Pixel *), minimum_area);
+
+  for (y = 0; y < height; ++y)
+    for (x = 0; x < width; ++x)
+      {
+        guchar has_stroke;
+
+        if (gimp_async_is_canceled (async))
+          {
+            gimp_async_abort (async);
+
+            goto end;
+          }
+
+        gegl_buffer_sample (buffer, x, y, NULL, &has_stroke, NULL,
+                            GEGL_SAMPLER_NEAREST, GEGL_ABYSS_NONE);
+        if (has_stroke && ! visited[x + y * width])
+          {
+            Pixel *p = g_new (Pixel, 1);
+            gint   regionSize = 0;
+
+            p->x = x;
+            p->y = y;
+
+            g_queue_push_tail (q, p);
+            visited[x + y * width] = TRUE;
+
+            while (! g_queue_is_empty (q))
+              {
+                Pixel *p;
+                gint   p2x;
+                gint   p2y;
+
+                if (gimp_async_is_canceled (async))
+                  {
+                    gimp_async_abort (async);
+
+                    goto end;
+                  }
+
+                p = (Pixel *) g_queue_pop_head (q);
+
+                p2x = p->x + 1;
+                p2y = p->y;
+                if (p2x >= 0 && p2x < width && p2y >= 0 && p2y < height)
+                  {
+                    gegl_buffer_sample (buffer, p2x, p2y, NULL, &has_stroke, NULL,
+                                        GEGL_SAMPLER_NEAREST, GEGL_ABYSS_NONE);
+                    if (has_stroke && ! visited[p2x + p2y * width])
+                      {
+                        Pixel *p2 = g_new (Pixel, 1);
+
+                        p2->x = p2x;
+                        p2->y = p2y;
+                        g_queue_push_tail (q, p2);
+                        visited[p2x +p2y * width] = TRUE;
+                      }
+                  }
+                p2x = p->x - 1;
+                p2y = p->y;
+                if (p2x >= 0 && p2x < width && p2y >= 0 && p2y < height)
+                  {
+                    gegl_buffer_sample (buffer, p2x, p2y, NULL, &has_stroke, NULL,
+                                        GEGL_SAMPLER_NEAREST, GEGL_ABYSS_NONE);
+                    if (has_stroke && ! visited[p2x + p2y * width])
+                      {
+                        Pixel *p2 = g_new (Pixel, 1);
+
+                        p2->x = p2x;
+                        p2->y = p2y;
+                        g_queue_push_tail (q, p2);
+                        visited[p2x + p2y * width] = TRUE;
+                      }
+                  }
+                p2x = p->x;
+                p2y = p->y - 1;
+                if (p2x >= 0 && p2x < width && p2y >= 0 && p2y < height)
+                  {
+                    gegl_buffer_sample (buffer, p2x, p2y, NULL, &has_stroke, NULL,
+                                        GEGL_SAMPLER_NEAREST, GEGL_ABYSS_NONE);
+                    if (has_stroke && ! visited[p2x + p2y * width])
+                      {
+                        Pixel *p2 = g_new (Pixel, 1);
+
+                        p2->x = p2x;
+                        p2->y = p2y;
+                        g_queue_push_tail (q, p2);
+                        visited[p2x + p2y * width] = TRUE;
+                      }
+                  }
+                p2x = p->x;
+                p2y = p->y + 1;
+                if (p2x >= 0 && p2x < width && p2y >= 0 && p2y < height)
+                  {
+                    gegl_buffer_sample (buffer, p2x, p2y, NULL, &has_stroke, NULL,
+                                        GEGL_SAMPLER_NEAREST, GEGL_ABYSS_NONE);
+                    if (has_stroke && ! visited[p2x + p2y * width])
+                      {
+                        Pixel *p2 = g_new (Pixel, 1);
+
+                        p2->x = p2x;
+                        p2->y = p2y;
+                        g_queue_push_tail (q, p2);
+                        visited[p2x + p2y * width] = TRUE;
+                      }
+                  }
+                p2x = p->x + 1;
+                p2y = p->y + 1;
+                if (p2x >= 0 && p2x < width && p2y >= 0 && p2y < height)
+                  {
+                    gegl_buffer_sample (buffer, p2x, p2y, NULL, &has_stroke, NULL,
+                                        GEGL_SAMPLER_NEAREST, GEGL_ABYSS_NONE);
+                    if (has_stroke && ! visited[p2x + p2y * width])
+                      {
+                        Pixel *p2 = g_new (Pixel, 1);
+
+                        p2->x = p2x;
+                        p2->y = p2y;
+                        g_queue_push_tail (q, p2);
+                        visited[p2x + p2y * width] = TRUE;
+                      }
+                  }
+                p2x = p->x - 1;
+                p2y = p->y - 1;
+                if (p2x >= 0 && p2x < width && p2y >= 0 && p2y < height)
+                  {
+                    gegl_buffer_sample (buffer, p2x, p2y, NULL, &has_stroke, NULL,
+                                        GEGL_SAMPLER_NEAREST, GEGL_ABYSS_NONE);
+                    if (has_stroke && ! visited[p2x + p2y * width])
+                      {
+                        Pixel *p2 = g_new (Pixel, 1);
+
+                        p2->x = p2x;
+                        p2->y = p2y;
+                        g_queue_push_tail (q, p2);
+                        visited[p2x + p2y * width] = TRUE;
+                      }
+                  }
+                p2x = p->x - 1;
+                p2y = p->y + 1;
+                if (p2x >= 0 && p2x < width && p2y >= 0 && p2y < height)
+                  {
+                    gegl_buffer_sample (buffer, p2x, p2y, NULL, &has_stroke, NULL,
+                                        GEGL_SAMPLER_NEAREST, GEGL_ABYSS_NONE);
+                    if (has_stroke && ! visited[p2x + p2y * width])
+                      {
+                        Pixel *p2 = g_new (Pixel, 1);
+
+                        p2->x = p2x;
+                        p2->y = p2y;
+                        g_queue_push_tail (q, p2);
+                        visited[p2x + p2y * width] = TRUE;
+                      }
+                  }
+                p2x = p->x + 1;
+                p2y = p->y - 1;
+                if (p2x >= 0 && p2x < width && p2y >= 0 && p2y < height)
+                  {
+                    gegl_buffer_sample (buffer, p2x, p2y, NULL, &has_stroke, NULL,
+                                        GEGL_SAMPLER_NEAREST, GEGL_ABYSS_NONE);
+                    if (has_stroke && ! visited[p2x + p2y * width])
+                      {
+                        Pixel *p2 = g_new (Pixel, 1);
+
+                        p2->x = p2x;
+                        p2->y = p2y;
+                        g_queue_push_tail (q, p2);
+                        visited[p2x + p2y * width] = TRUE;
+                      }
+                  }
+
+                ++regionSize;
+                if (regionSize < minimum_area)
+                  g_array_append_val (region, *p);
+                g_free (p);
+              }
+            if (regionSize < minimum_area)
+              {
+                Pixel *pixel = (Pixel *) region->data;
+                gint   i = 0;
+
+                for (; i < region->len; i++)
+                  {
+                    guchar val = 0;
+                    gegl_buffer_set (buffer, GEGL_RECTANGLE (pixel->x, pixel->y, 1, 1), 0,
+                                     NULL, &val, GEGL_AUTO_ROWSTRIDE);
+                    pixel++;
+                  }
+              }
+            g_array_remove_range (region, 0, region->len);
+          }
+      }
+
+ end:
+  g_array_free (region, TRUE);
+  g_queue_free_full (q, g_free);
+  g_free (visited);
+}
+
+static void
+gimp_lineart_compute_normals_curvatures (GeglBuffer *mask,
+                                         gfloat     *normals,
+                                         gfloat     *curvatures,
+                                         gfloat     *smoothed_curvatures,
+                                         int         normal_estimate_mask_size,
+                                         GimpAsync  *async)
+{
+  gfloat  *edgels_curvatures  = NULL;
+  gfloat  *smoothed_curvature;
+  GArray  *es                 = NULL;
+  Edgel  **e;
+  gint     width              = gegl_buffer_get_width (mask);
+
+  es = gimp_edgelset_new (mask, async);
+  if (gimp_async_is_stopped (async))
+    goto end;
+
+  e = (Edgel **) es->data;
+
+  gimp_edgelset_smooth_normals (es, normal_estimate_mask_size, async);
+  if (gimp_async_is_stopped (async))
+    goto end;
+
+  gimp_edgelset_compute_curvature (es, async);
+  if (gimp_async_is_stopped (async))
+    goto end;
+
+  while (*e)
+    {
+      const float curvature = ((*e)->curvature > 0.0f) ? (*e)->curvature : 0.0f;
+      const float w         = MAX (1e-8f, curvature * curvature);
+
+      if (gimp_async_is_canceled (async))
+        {
+          gimp_async_abort (async);
+
+          goto end;
+        }
+
+      normals[((*e)->x + (*e)->y * width) * 2] += w * (*e)->x_normal;
+      normals[((*e)->x + (*e)->y * width) * 2 + 1] += w * (*e)->y_normal;
+      curvatures[(*e)->x + (*e)->y * width] = MAX (curvature,
+                                                   curvatures[(*e)->x + (*e)->y * width]);
+      e++;
+    }
+  for (int y = 0; y < gegl_buffer_get_height (mask); ++y)
+    {
+      if (gimp_async_is_canceled (async))
+        {
+          gimp_async_abort (async);
+
+          goto end;
+        }
+
+      for (int x = 0; x < gegl_buffer_get_width (mask); ++x)
+        {
+          const float _angle = atan2f (normals[(x + y * width) * 2 + 1],
+                                       normals[(x + y * width) * 2]);
+          normals[(x + y * width) * 2] = cosf (_angle);
+          normals[(x + y * width) * 2 + 1] = sinf (_angle);
+        }
+    }
+
+  /* Smooth curvatures on edgels, then take maximum on each pixel. */
+  edgels_curvatures = gimp_lineart_get_smooth_curvatures (es, async);
+  if (gimp_async_is_stopped (async))
+    goto end;
+
+  smoothed_curvature = edgels_curvatures;
+
+  e = (Edgel **) es->data;
+  while (*e)
+    {
+      gfloat *pixel_curvature = &smoothed_curvatures[(*e)->x + (*e)->y * width];
+
+      if (*pixel_curvature < *smoothed_curvature)
+        *pixel_curvature = *smoothed_curvature;
+
+      ++smoothed_curvature;
+      e++;
+    }
+
+ end:
+  g_free (edgels_curvatures);
+
+  if (es)
+    g_array_free (es, TRUE);
+}
+
+static gfloat *
+gimp_lineart_get_smooth_curvatures (GArray    *edgelset,
+                                    GimpAsync *async)
+{
+  Edgel  **e;
+  gfloat  *smoothed_curvatures = g_new0 (gfloat, edgelset->len);
+  gfloat   weights[9];
+  gfloat   smoothed_curvature;
+  gfloat   weights_sum;
+  gint     idx = 0;
+
+  weights[0] = 1.0f;
+  for (int i = 1; i <= 8; ++i)
+    weights[i] = expf (-(i * i) / 30.0f);
+
+  e = (Edgel **) edgelset->data;
+  while (*e)
+    {
+      Edgel *edgel_before = g_array_index (edgelset, Edgel*, (*e)->previous);
+      Edgel *edgel_after  = g_array_index (edgelset, Edgel*, (*e)->next);
+      int    n = 5;
+      int    i = 1;
+
+      if (gimp_async_is_canceled (async))
+        {
+          gimp_async_abort (async);
+
+          g_free (smoothed_curvatures);
+
+          return NULL;
+        }
+
+      smoothed_curvature = (*e)->curvature;
+      weights_sum = weights[0];
+      while (n-- && (edgel_after != edgel_before))
+        {
+          smoothed_curvature += weights[i] * edgel_before->curvature;
+          smoothed_curvature += weights[i] * edgel_after->curvature;
+          edgel_before = g_array_index (edgelset, Edgel*, edgel_before->previous);
+          edgel_after  = g_array_index (edgelset, Edgel*, edgel_after->next);
+          weights_sum += 2 * weights[i];
+          i++;
+        }
+      smoothed_curvature /= weights_sum;
+      smoothed_curvatures[idx++] = smoothed_curvature;
+
+      e++;
+    }
+
+  return smoothed_curvatures;
+}
+
+/**
+ * Keep one pixel per connected component of curvature extremums.
+ */
+static GArray *
+gimp_lineart_curvature_extremums (gfloat    *curvatures,
+                                  gfloat    *smoothed_curvatures,
+                                  gint       width,
+                                  gint       height,
+                                  GimpAsync *async)
+{
+  gboolean *visited = g_new0 (gboolean, width * height);
+  GQueue   *q       = g_queue_new ();
+  GArray   *max_positions;
+
+  max_positions = g_array_new (FALSE, TRUE, sizeof (Pixel));
+
+  for (int y = 0; y < height; ++y)
+    {
+      if (gimp_async_is_canceled (async))
+        {
+          gimp_async_abort (async);
+
+          goto end;
+        }
+
+      for (int x = 0; x < width; ++x)
+        {
+          if ((curvatures[x + y * width] > 0.0) && ! visited[x + y * width])
+            {
+              Pixel  *p = g_new (Pixel, 1);
+              Pixel   max_smoothed_curvature_pixel;
+              Pixel   max_raw_curvature_pixel;
+              gfloat  max_smoothed_curvature;
+              gfloat  max_raw_curvature;
+
+              max_smoothed_curvature_pixel = gimp_vector2_new (-1.0, -1.0);
+              max_smoothed_curvature       = 0.0f;
+
+              max_raw_curvature_pixel = gimp_vector2_new (x, y);
+              max_raw_curvature       = curvatures[x + y * width];
+
+              p->x = x;
+              p->y = y;
+              g_queue_push_tail (q, p);
+              visited[x + y * width] = TRUE;
+
+              while (! g_queue_is_empty (q))
+                {
+                  gfloat sc;
+                  gfloat c;
+                  gint   p2x;
+                  gint   p2y;
+
+                  if (gimp_async_is_canceled (async))
+                    {
+                      gimp_async_abort (async);
+
+                      goto end;
+                    }
+
+                  p  = (Pixel *) g_queue_pop_head (q);
+                  sc = smoothed_curvatures[(gint) p->x + (gint) p->y * width];
+                  c  = curvatures[(gint) p->x + (gint) p->y * width];
+
+                  curvatures[(gint) p->x + (gint) p->y * width] = 0.0f;
+
+                  p2x = (gint) p->x + 1;
+                  p2y = (gint) p->y;
+                  if (p2x >= 0 && p2x < width    &&
+                      p2y >= 0 && p2y < height   &&
+                      curvatures[p2x + p2y * width] > 0.0 &&
+                      ! visited[p2x + p2y * width])
+                    {
+                      Pixel *p2 = g_new (Pixel, 1);
+
+                      p2->x = p2x;
+                      p2->y = p2y;
+                      g_queue_push_tail (q, p2);
+                      visited[p2x + p2y * width] = TRUE;
+                    }
+
+                  p2x = p->x - 1;
+                  p2y = p->y;
+                  if (p2x >= 0 && p2x < width    &&
+                      p2y >= 0 && p2y < height   &&
+                      curvatures[p2x + p2y * width] > 0.0 &&
+                      ! visited[p2x + p2y * width])
+                    {
+                      Pixel *p2 = g_new (Pixel, 1);
+
+                      p2->x = p2x;
+                      p2->y = p2y;
+                      g_queue_push_tail (q, p2);
+                      visited[p2x + p2y * width] = TRUE;
+                    }
+
+                  p2x = p->x;
+                  p2y = p->y - 1;
+                  if (p2x >= 0 && p2x < width    &&
+                      p2y >= 0 && p2y < height   &&
+                      curvatures[p2x + p2y * width] > 0.0 &&
+                      ! visited[p2x + p2y * width])
+                    {
+                      Pixel *p2 = g_new (Pixel, 1);
+
+                      p2->x = p2x;
+                      p2->y = p2y;
+                      g_queue_push_tail (q, p2);
+                      visited[p2x + p2y * width] = TRUE;
+                    }
+
+                  p2x = p->x;
+                  p2y = p->y + 1;
+                  if (p2x >= 0 && p2x < width    &&
+                      p2y >= 0 && p2y < height   &&
+                      curvatures[p2x + p2y * width] > 0.0 &&
+                      ! visited[p2x + p2y * width])
+                    {
+                      Pixel *p2 = g_new (Pixel, 1);
+
+                      p2->x = p2x;
+                      p2->y = p2y;
+                      g_queue_push_tail (q, p2);
+                      visited[p2x + p2y * width] = TRUE;
+                    }
+
+                  p2x = p->x + 1;
+                  p2y = p->y + 1;
+                  if (p2x >= 0 && p2x < width    &&
+                      p2y >= 0 && p2y < height   &&
+                      curvatures[p2x + p2y * width] > 0.0 &&
+                      ! visited[p2x + p2y * width])
+                    {
+                      Pixel *p2 = g_new (Pixel, 1);
+
+                      p2->x = p2x;
+                      p2->y = p2y;
+                      g_queue_push_tail (q, p2);
+                      visited[p2x + p2y * width] = TRUE;
+                    }
+
+                  p2x = p->x - 1;
+                  p2y = p->y - 1;
+                  if (p2x >= 0 && p2x < width    &&
+                      p2y >= 0 && p2y < height   &&
+                      curvatures[p2x + p2y * width] > 0.0 &&
+                      ! visited[p2x + p2y * width])
+                    {
+                      Pixel *p2 = g_new (Pixel, 1);
+
+                      p2->x = p2x;
+                      p2->y = p2y;
+                      g_queue_push_tail (q, p2);
+                      visited[p2x + p2y * width] = TRUE;
+                    }
+
+                  p2x = p->x - 1;
+                  p2y = p->y + 1;
+                  if (p2x >= 0 && p2x < width    &&
+                      p2y >= 0 && p2y < height   &&
+                      curvatures[p2x + p2y * width] > 0.0 &&
+                      ! visited[p2x + p2y * width])
+                    {
+                      Pixel *p2 = g_new (Pixel, 1);
+
+                      p2->x = p2x;
+                      p2->y = p2y;
+                      g_queue_push_tail (q, p2);
+                      visited[p2x + p2y * width] = TRUE;
+                    }
+
+                  p2x = p->x + 1;
+                  p2y = p->y - 1;
+                  if (p2x >= 0 && p2x < width    &&
+                      p2y >= 0 && p2y < height   &&
+                      curvatures[p2x + p2y * width] > 0.0 &&
+                      ! visited[p2x + p2y * width])
+                    {
+                      Pixel *p2 = g_new (Pixel, 1);
+
+                      p2->x = p2x;
+                      p2->y = p2y;
+                      g_queue_push_tail (q, p2);
+                      visited[p2x + p2y * width] = TRUE;
+                    }
+
+                  if (sc > max_smoothed_curvature)
+                    {
+                      max_smoothed_curvature_pixel = *p;
+                      max_smoothed_curvature = sc;
+                    }
+                  if (c > max_raw_curvature)
+                    {
+                      max_raw_curvature_pixel = *p;
+                      max_raw_curvature = c;
+                    }
+                  g_free (p);
+                }
+              if (max_smoothed_curvature > 0.0f)
+                {
+                  curvatures[(gint) max_smoothed_curvature_pixel.x + (gint) max_smoothed_curvature_pixel.y * width] = max_smoothed_curvature;
+                  g_array_append_val (max_positions, max_smoothed_curvature_pixel);
+                }
+              else
+                {
+                  curvatures[(gint) max_raw_curvature_pixel.x + (gint) max_raw_curvature_pixel.y * width] = max_raw_curvature;
+                  g_array_append_val (max_positions, max_raw_curvature_pixel);
+                }
+            }
+        }
+    }
+
+ end:
+  g_queue_free_full (q, g_free);
+  g_free (visited);
+
+  if (gimp_async_is_stopped (async))
+    {
+      g_array_free (max_positions, TRUE);
+      max_positions = NULL;
+    }
+
+  return max_positions;
+}
+
+static gint
+gimp_spline_candidate_cmp (const SplineCandidate *a,
+                           const SplineCandidate *b,
+                           gpointer               user_data)
+{
+  /* This comparison actually returns the opposite of common comparison
+   * functions on purpose, as we want the first element on the list to
+   * be the "bigger".
+   */
+  if (a->quality < b->quality)
+    return 1;
+  else if (a->quality > b->quality)
+    return -1;
+  else
+    return 0;
+}
+
+static GList *
+gimp_lineart_find_spline_candidates (GArray    *max_positions,
+                                     gfloat    *normals,
+                                     gint       width,
+                                     gint       distance_threshold,
+                                     gfloat     max_angle_deg,
+                                     GimpAsync *async)
+{
+  GList       *candidates = NULL;
+  const float  CosMin     = cosf (M_PI * (max_angle_deg / 180.0));
+  gint         i;
+
+  for (i = 0; i < max_positions->len; i++)
+    {
+      Pixel p1 = g_array_index (max_positions, Pixel, i);
+      gint  j;
+
+      if (gimp_async_is_canceled (async))
+        {
+          gimp_async_abort (async);
+
+          g_list_free_full (candidates, g_free);
+
+          return NULL;
+        }
+
+      for (j = i + 1; j < max_positions->len; j++)
+        {
+          Pixel       p2 = g_array_index (max_positions, Pixel, j);
+          const float distance = gimp_vector2_length_val (gimp_vector2_sub_val (p1, p2));
+
+          if (distance <= distance_threshold)
+            {
+              GimpVector2 normalP1;
+              GimpVector2 normalP2;
+              GimpVector2 p1f;
+              GimpVector2 p2f;
+              GimpVector2 p1p2;
+              float       cosN;
+              float       qualityA;
+              float       qualityB;
+              float       qualityC;
+              float       quality;
+
+              normalP1 = gimp_vector2_new (normals[((gint) p1.x + (gint) p1.y * width) * 2],
+                                           normals[((gint) p1.x + (gint) p1.y * width) * 2 + 1]);
+              normalP2 = gimp_vector2_new (normals[((gint) p2.x + (gint) p2.y * width) * 2],
+                                           normals[((gint) p2.x + (gint) p2.y * width) * 2 + 1]);
+              p1f = gimp_vector2_new (p1.x, p1.y);
+              p2f = gimp_vector2_new (p2.x, p2.y);
+              p1p2 = gimp_vector2_sub_val (p2f, p1f);
+
+              cosN = gimp_vector2_inner_product_val (normalP1, (gimp_vector2_neg_val (normalP2)));
+              qualityA = MAX (0.0f, 1 - distance / distance_threshold);
+              qualityB = MAX (0.0f,
+                              (float) (gimp_vector2_inner_product_val (normalP1, p1p2) - gimp_vector2_inner_product_val (normalP2, p1p2)) /
+                              distance);
+              qualityC = MAX (0.0f, cosN - CosMin);
+              quality = qualityA * qualityB * qualityC;
+              if (quality > 0)
+                {
+                  SplineCandidate *candidate = g_new (SplineCandidate, 1);
+
+                  candidate->p1      = p1;
+                  candidate->p2      = p2;
+                  candidate->quality = quality;
+
+                  candidates = g_list_insert_sorted_with_data (candidates, candidate,
+                                                               (GCompareDataFunc) gimp_spline_candidate_cmp,
+                                                               NULL);
+                }
+            }
+        }
+    }
+  return candidates;
+}
+
+static GArray *
+gimp_lineart_discrete_spline (Pixel       p0,
+                              GimpVector2 n0,
+                              Pixel       p1,
+                              GimpVector2 n1)
+{
+  GArray       *points = g_array_new (FALSE, TRUE, sizeof (Pixel));
+  const double  a0 = 2 * p0.x - 2 * p1.x + n0.x - n1.x;
+  const double  b0 = -3 * p0.x + 3 * p1.x - 2 * n0.x + n1.x;
+  const double  c0 = n0.x;
+  const double  d0 = p0.x;
+  const double  a1 = 2 * p0.y - 2 * p1.y + n0.y - n1.y;
+  const double  b1 = -3 * p0.y + 3 * p1.y - 2 * n0.y + n1.y;
+  const double  c1 = n0.y;
+  const double  d1 = p0.y;
+
+  double        t = 0.0;
+  const double  dtMin = 1.0 / MAX (fabs (p0.x - p1.x), fabs (p0.y - p1.y));
+  Pixel         point = gimp_vector2_new ((gint) round (d0), (gint) round (d1));
+
+  g_array_append_val (points, point);
+
+  while (t <= 1.0)
+    {
+      const double t2 = t * t;
+      const double t3 = t * t2;
+      double       dx;
+      double       dy;
+      Pixel        p = gimp_vector2_new ((gint) round (a0 * t3 + b0 * t2 + c0 * t + d0),
+                                         (gint) round (a1 * t3 + b1 * t2 + c1 * t + d1));
+
+      /* create gimp_vector2_neq () ? */
+      if (g_array_index (points, Pixel, points->len - 1).x != p.x ||
+          g_array_index (points, Pixel, points->len - 1).y != p.y)
+        {
+          g_array_append_val (points, p);
+        }
+      dx = fabs (3 * a0 * t * t + 2 * b0 * t + c0) + 1e-8;
+      dy = fabs (3 * a1 * t * t + 2 * b1 * t + c1) + 1e-8;
+      t += MIN (dtMin, 0.75 / MAX (dx, dy));
+    }
+  if (g_array_index (points, Pixel, points->len - 1).x != p1.x ||
+      g_array_index (points, Pixel, points->len - 1).y != p1.y)
+    {
+      g_array_append_val (points, p1);
+    }
+  return points;
+}
+
+static gint
+gimp_number_of_transitions (GArray     *pixels,
+                            GeglBuffer *buffer)
+{
+  int result = 0;
+
+  if (pixels->len > 0)
+    {
+      Pixel    it = g_array_index (pixels, Pixel, 0);
+      guchar   value;
+      gboolean previous;
+      gint     i;
+
+      gegl_buffer_sample (buffer, (gint) it.x, (gint) it.y, NULL, &value, NULL,
+                          GEGL_SAMPLER_NEAREST, GEGL_ABYSS_NONE);
+      previous = (gboolean) value;
+
+      /* Starts at the second element. */
+      for (i = 1; i < pixels->len; i++)
+        {
+          it = g_array_index (pixels, Pixel, i);
+
+          gegl_buffer_sample (buffer, (gint) it.x, (gint) it.y, NULL, &value, NULL,
+                              GEGL_SAMPLER_NEAREST, GEGL_ABYSS_NONE);
+          result += ((gboolean) value != previous);
+          previous = (gboolean) value;
+        }
+    }
+
+  return result;
+}
+
+/**
+ * gimp_line_art_allow_closure:
+ * @mask: the current state of line art closure.
+ * @pixels: the pixels of a candidate closure (spline or segment).
+ * @fill_pixels: #GList of unsignificant pixels to bucket fill.
+ * @significant_size: number of pixels for area to be considered
+ *                    "significant".
+ * @minimum_size: number of pixels for area to be allowed.
+ *
+ * Checks whether adding the set of points @pixels to @mask will create
+ * 4-connected background regions whose size (i.e. number of pixels)
+ * will be below @minimum_size. If it creates such small areas, the
+ * function will refuse this candidate spline/segment, with the
+ * exception of very small areas under @significant_size. These
+ * micro-area are considered "unsignificant" and accepted (because they
+ * can be created in some conditions, for instance when created curves
+ * cross or start from a same endpoint), and one pixel for each
+ * micro-area will be added to @fill_pixels to be later filled along
+ * with the candidate pixels.
+ *
+ * Returns: #TRUE if @pixels should be added to @mask, #FALSE otherwise.
+ */
+static gboolean
+gimp_line_art_allow_closure (GeglBuffer *mask,
+                             GArray     *pixels,
+                             GList     **fill_pixels,
+                             int         significant_size,
+                             int         minimum_size)
+{
+  /* A theorem from the paper is that a zone with more than
+   * `2 * (@minimum_size - 1)` edgels (border pixels) will have more
+   * than @minimum_size pixels.
+   * Since we are following the edges of the area, we can therefore stop
+   * earlier if we reach this number of edgels.
+   */
+  const glong max_edgel_count = 2 * minimum_size;
+
+  Pixel      *p = (Pixel*) pixels->data;
+  GList      *fp = NULL;
+  gint        i;
+
+  /* Mark pixels */
+  for (i = 0; i < pixels->len; i++)
+    {
+      if (p->x >= 0 && p->x < gegl_buffer_get_width (mask) &&
+          p->y >= 0 && p->y < gegl_buffer_get_height (mask))
+        {
+          guchar val;
+
+          gegl_buffer_sample (mask, (gint) p->x, (gint) p->y, NULL, &val,
+                              NULL, GEGL_SAMPLER_NEAREST, GEGL_ABYSS_NONE);
+          val = val ? 3 : 2;
+          gegl_buffer_set (mask, GEGL_RECTANGLE ((gint) p->x, (gint) p->y, 1, 1), 0,
+                           NULL, &val, GEGL_AUTO_ROWSTRIDE);
+        }
+      p++;
+    }
+
+  for (i = 0; i < pixels->len; i++)
+    {
+      Pixel p = g_array_index (pixels, Pixel, i);
+
+      for (int direction = 0; direction < 4; ++direction)
+        {
+          if (p.x >= 0 && p.x < gegl_buffer_get_width (mask) &&
+              p.y >= 0 && p.y < gegl_buffer_get_height (mask) &&
+              border_in_direction (mask, p, direction))
+            {
+              Edgel  e;
+              guchar val;
+              glong  count;
+              glong  area;
+
+              gegl_buffer_sample (mask, (gint) p.x, (gint) p.y, NULL, &val,
+                                  NULL, GEGL_SAMPLER_NEAREST, GEGL_ABYSS_NONE);
+              if ((gboolean) (val & (4 << direction)))
+                continue;
+
+              gimp_edgel_init (&e);
+              e.x = p.x;
+              e.y = p.y;
+              e.direction = direction;
+
+              count = gimp_edgel_track_mark (mask, e, max_edgel_count);
+              if ((count != -1) && (count <= max_edgel_count))
+                {
+                  area = gimp_edgel_region_area (mask, e);
+
+                  if (area >= significant_size && area < minimum_size)
+                    {
+                      gint j;
+
+                      /* Remove marks */
+                      for (j = 0; j < pixels->len; j++)
+                        {
+                          Pixel p2 = g_array_index (pixels, Pixel, j);
+
+                          if (p2.x >= 0 && p2.x < gegl_buffer_get_width (mask) &&
+                              p2.y >= 0 && p2.y < gegl_buffer_get_height (mask))
+                            {
+                              guchar val;
+
+                              gegl_buffer_sample (mask, (gint) p2.x, (gint) p2.y, NULL, &val,
+                                                  NULL, GEGL_SAMPLER_NEAREST, GEGL_ABYSS_NONE);
+                              val &= 1;
+                              gegl_buffer_set (mask, GEGL_RECTANGLE ((gint) p2.x, (gint) p2.y, 1, 1), 0,
+                                               NULL, &val, GEGL_AUTO_ROWSTRIDE);
+                            }
+                        }
+                      g_list_free_full (fp, g_free);
+
+                      return FALSE;
+                    }
+                  else if (area > 0 && area < significant_size)
+                    {
+                      Pixel *np = g_new (Pixel, 1);
+
+                      np->x = direction == XPlusDirection ? p.x + 1 : (direction == XMinusDirection ? p.x - 1 : p.x);
+                      np->y = direction == YPlusDirection ? p.y + 1 : (direction == YMinusDirection ? p.y - 1 : p.y);
+
+                      if (np->x >= 0 && np->x < gegl_buffer_get_width (mask) &&
+                          np->y >= 0 && np->y < gegl_buffer_get_height (mask))
+                        fp = g_list_prepend (fp, np);
+                      else
+                        g_free (np);
+                    }
+                }
+            }
+        }
+    }
+
+  *fill_pixels = g_list_concat (*fill_pixels, fp);
+  /* Remove marks */
+  for (i = 0; i < pixels->len; i++)
+    {
+      Pixel p = g_array_index (pixels, Pixel, i);
+
+      if (p.x >= 0 && p.x < gegl_buffer_get_width (mask) &&
+          p.y >= 0 && p.y < gegl_buffer_get_height (mask))
+        {
+          guchar val;
+
+          gegl_buffer_sample (mask, (gint) p.x, (gint) p.y, NULL, &val,
+                              NULL, GEGL_SAMPLER_NEAREST, GEGL_ABYSS_NONE);
+          val &= 1;
+          gegl_buffer_set (mask, GEGL_RECTANGLE ((gint) p.x, (gint) p.y, 1, 1), 0,
+                           NULL, &val, GEGL_AUTO_ROWSTRIDE);
+        }
+    }
+  return TRUE;
+}
+
+static GArray *
+gimp_lineart_line_segment_until_hit (const GeglBuffer *mask,
+                                     Pixel             start,
+                                     GimpVector2       direction,
+                                     int               size)
+{
+  GeglBuffer  *buffer = (GeglBuffer *) mask;
+  gboolean     out = FALSE;
+  GArray      *points = g_array_new (FALSE, TRUE, sizeof (Pixel));
+  int          tmax;
+  GimpVector2  p0 = gimp_vector2_new (start.x, start.y);
+
+  gimp_vector2_mul (&direction, (gdouble) size);
+  direction.x = round (direction.x);
+  direction.y = round (direction.y);
+
+  tmax = MAX (abs ((int) direction.x), abs ((int) direction.y));
+
+  for (int t = 0; t <= tmax; ++t)
+    {
+      GimpVector2 v = gimp_vector2_add_val (p0, gimp_vector2_mul_val (direction, (float)t / tmax));
+      Pixel       p;
+
+      p.x = (gint) round (v.x);
+      p.y = (gint) round (v.y);
+      if (p.x >= 0 && p.x < gegl_buffer_get_width (buffer) &&
+          p.y >= 0 && p.y < gegl_buffer_get_height (buffer))
+        {
+          guchar val;
+          gegl_buffer_sample (buffer, p.x, p.y, NULL, &val,
+                              NULL, GEGL_SAMPLER_NEAREST, GEGL_ABYSS_NONE);
+          if (out && val)
+            {
+              return points;
+            }
+          out = ! val;
+        }
+      else if (out)
+        {
+          return points;
+        }
+      else
+        {
+          g_array_free (points, TRUE);
+          return g_array_new (FALSE, TRUE, sizeof (Pixel));
+        }
+      g_array_append_val (points, p);
+    }
+
+  g_array_free (points, TRUE);
+  return g_array_new (FALSE, TRUE, sizeof (Pixel));
+}
+
+static gfloat *
+gimp_lineart_estimate_strokes_radii (GeglBuffer *mask,
+                                     GimpAsync  *async)
+{
+  GeglBufferIterator *gi;
+  gfloat             *dist;
+  gfloat             *thickness;
+  GeglNode           *graph;
+  GeglNode           *input;
+  GeglNode           *op;
+  gint                width  = gegl_buffer_get_width (mask);
+  gint                height = gegl_buffer_get_height (mask);
+
+  /* Compute a distance map for the line art. */
+  dist = g_new (gfloat, width * height);
+
+  graph = gegl_node_new ();
+  input = gegl_node_new_child (graph,
+                               "operation", "gegl:buffer-source",
+                               "buffer", mask,
+                               NULL);
+  op  = gegl_node_new_child (graph,
+                             "operation", "gegl:distance-transform",
+                             "metric",    GEGL_DISTANCE_METRIC_EUCLIDEAN,
+                             "normalize", FALSE,
+                             NULL);
+  gegl_node_connect_to (input, "output", op, "input");
+  gegl_node_blit (op, 1.0, gegl_buffer_get_extent (mask),
+                  NULL, dist, GEGL_AUTO_ROWSTRIDE, GEGL_BLIT_DEFAULT);
+  g_object_unref (graph);
+
+  thickness = g_new0 (gfloat, width * height);
+  gi = gegl_buffer_iterator_new (mask, NULL, 0, NULL,
+                                 GEGL_ACCESS_READ, GEGL_ABYSS_NONE, 1);
+  while (gegl_buffer_iterator_next (gi))
+    {
+      guint8 *m = (guint8*) gi->items[0].data;
+      gint    startx = gi->items[0].roi.x;
+      gint    starty = gi->items[0].roi.y;
+      gint    endy   = starty + gi->items[0].roi.height;
+      gint    endx   = startx + gi->items[0].roi.width;
+      gint    x;
+      gint    y;
+
+      if (gimp_async_is_canceled (async))
+        {
+          gegl_buffer_iterator_stop (gi);
+
+          gimp_async_abort (async);
+
+          goto end;
+        }
+
+      for (y = starty; y < endy; y++)
+        for (x = startx; x < endx; x++)
+          {
+            if (*m && dist[x + y * width] == 1.0)
+              {
+                gint     dx = x;
+                gint     dy = y;
+                gfloat   d  = 1.0;
+                gfloat   nd;
+                gboolean neighbour_thicker = TRUE;
+
+                while (neighbour_thicker)
+                  {
+                    gint px = dx - 1;
+                    gint py = dy - 1;
+                    gint nx = dx + 1;
+                    gint ny = dy + 1;
+
+                    neighbour_thicker = FALSE;
+                    if (px >= 0)
+                      {
+                        if ((nd = dist[px + dy * width]) > d)
+                          {
+                            d = nd;
+                            dx = px;
+                            neighbour_thicker = TRUE;
+                            continue;
+                          }
+                        if (py >= 0 && (nd = dist[px + py * width]) > d)
+                          {
+                            d = nd;
+                            dx = px;
+                            dy = py;
+                            neighbour_thicker = TRUE;
+                            continue;
+                          }
+                        if (ny < height && (nd = dist[px + ny * width]) > d)
+                          {
+                            d = nd;
+                            dx = px;
+                            dy = ny;
+                            neighbour_thicker = TRUE;
+                            continue;
+                          }
+                      }
+                    if (nx < width)
+                      {
+                        if ((nd = dist[nx + dy * width]) > d)
+                          {
+                            d = nd;
+                            dx = nx;
+                            neighbour_thicker = TRUE;
+                            continue;
+                          }
+                        if (py >= 0 && (nd = dist[nx + py * width]) > d)
+                          {
+                            d = nd;
+                            dx = nx;
+                            dy = py;
+                            neighbour_thicker = TRUE;
+                            continue;
+                          }
+                        if (ny < height && (nd = dist[nx + ny * width]) > d)
+                          {
+                            d = nd;
+                            dx = nx;
+                            dy = ny;
+                            neighbour_thicker = TRUE;
+                            continue;
+                          }
+                      }
+                    if (py > 0 && (nd = dist[dx + py * width]) > d)
+                      {
+                        d = nd;
+                        dy = py;
+                        neighbour_thicker = TRUE;
+                        continue;
+                      }
+                    if (ny < height && (nd = dist[dx + ny * width]) > d)
+                      {
+                        d = nd;
+                        dy = ny;
+                        neighbour_thicker = TRUE;
+                        continue;
+                      }
+                  }
+                thickness[(gint) x + (gint) y * width] = d;
+              }
+            m++;
+          }
+    }
+
+ end:
+  g_free (dist);
+
+  if (gimp_async_is_stopped (async))
+    g_clear_pointer (&thickness, g_free);
+
+  return thickness;
+}
+
+static void
+gimp_line_art_simple_fill (GeglBuffer *buffer,
+                           gint        x,
+                           gint        y,
+                           gint       *counter)
+{
+  guchar val;
+
+  if (x < 0 || x >= gegl_buffer_get_width (buffer)  ||
+      y < 0 || y >= gegl_buffer_get_height (buffer) ||
+      *counter <= 0)
+    return;
+
+  gegl_buffer_sample (buffer, x, y, NULL, &val,
+                      NULL, GEGL_SAMPLER_NEAREST, GEGL_ABYSS_NONE);
+
+  if (! val)
+    {
+      val = 1;
+      gegl_buffer_set (buffer, GEGL_RECTANGLE (x, y, 1, 1), 0,
+                       NULL, &val, GEGL_AUTO_ROWSTRIDE);
+      (*counter)--;
+      gimp_line_art_simple_fill (buffer, x + 1, y, counter);
+      gimp_line_art_simple_fill (buffer, x - 1, y, counter);
+      gimp_line_art_simple_fill (buffer, x, y + 1, counter);
+      gimp_line_art_simple_fill (buffer, x, y - 1, counter);
+    }
+}
+
+static guint
+visited_hash_fun (Pixel *key)
+{
+  /* Cantor pairing function. */
+  return (key->x + key->y) * (key->x + key->y + 1) / 2 + key->y;
+}
+
+static gboolean
+visited_equal_fun (Pixel *e1,
+                   Pixel *e2)
+{
+  return (e1->x == e2->x && e1->y == e2->y);
+}
+
+static inline gboolean
+border_in_direction (GeglBuffer *mask,
+                     Pixel       p,
+                     int         direction)
+{
+  gint px = (gint) p.x + DeltaX[direction];
+  gint py = (gint) p.y + DeltaY[direction];
+
+  if (px >= 0 && px < gegl_buffer_get_width (mask) &&
+      py >= 0 && py < gegl_buffer_get_height (mask))
+    {
+      guchar val;
+
+      gegl_buffer_sample (mask, px, py, NULL, &val,
+                          NULL, GEGL_SAMPLER_NEAREST, GEGL_ABYSS_NONE);
+      return ! ((gboolean) val);
+    }
+  return TRUE;
+}
+
+static inline GimpVector2
+pair2normal (Pixel   p,
+             gfloat *normals,
+             gint    width)
+{
+  return gimp_vector2_new (normals[((gint) p.x + (gint) p.y * width) * 2],
+                           normals[((gint) p.x + (gint) p.y * width) * 2 + 1]);
+}
+/* Edgel functions */
+
+static Edgel *
+gimp_edgel_new (int       x,
+                int       y,
+                Direction direction)
+{
+  Edgel *edgel = g_new (Edgel, 1);
+
+  edgel->x         = x;
+  edgel->y         = y;
+  edgel->direction = direction;
+
+  gimp_edgel_init (edgel);
+
+  return edgel;
+}
+
+static void
+gimp_edgel_init (Edgel *edgel)
+{
+  edgel->x_normal  = 0;
+  edgel->y_normal  = 0;
+  edgel->curvature = 0;
+  edgel->next      = edgel->previous = G_MAXUINT;
+}
+
+static void
+gimp_edgel_clear (Edgel **edgel)
+{
+  g_clear_pointer (edgel, g_free);
+}
+
+static int
+gimp_edgel_cmp (const Edgel* e1,
+                const Edgel* e2)
+{
+  gimp_assert (e1 && e2);
+
+  if ((e1->x == e2->x) && (e1->y == e2->y) &&
+      (e1->direction == e2->direction))
+    return 0;
+  else if ((e1->y < e2->y) || (e1->y == e2->y && e1->x < e2->x) ||
+           (e1->y == e2->y && e1->x == e2->x && e1->direction < e2->direction))
+    return -1;
+  else
+    return 1;
+}
+
+static guint
+edgel2index_hash_fun (Edgel *key)
+{
+  /* Cantor pairing function.
+   * Was not sure how to use the direction though. :-/
+   */
+  return (key->x + key->y) * (key->x + key->y + 1) / 2 + key->y * key->direction;
+}
+
+static gboolean
+edgel2index_equal_fun (Edgel *e1,
+                       Edgel *e2)
+{
+  return (e1->x == e2->x && e1->y == e2->y &&
+          e1->direction == e2->direction);
+}
+
+/**
+ * @mask;
+ * @edgel:
+ * @size_limit:
+ *
+ * Track a border, marking inner pixels with a bit corresponding to the
+ * edgel traversed (4 << direction) for direction in {0,1,2,3}.
+ * Stop tracking after @size_limit edgels have been visited.
+ *
+ * Returns: Number of visited edgels, or -1 if an already visited edgel
+ *          has been encountered.
+ */
+static glong
+gimp_edgel_track_mark (GeglBuffer *mask,
+                       Edgel       edgel,
+                       long        size_limit)
+{
+  Edgel start = edgel;
+  long  count = 1;
+
+  do
+    {
+      guchar val;
+
+      gimp_edgelset_next8 (mask, &edgel, &edgel);
+      gegl_buffer_sample (mask, edgel.x, edgel.y, NULL, &val,
+                          NULL, GEGL_SAMPLER_NEAREST, GEGL_ABYSS_NONE);
+      if (val & 2)
+        {
+          /* Only mark pixels of the spline/segment */
+          if (val & (4 << edgel.direction))
+            return -1;
+
+          /* Mark edgel in pixel (1 == In Mask, 2 == Spline/Segment) */
+          val |= (4 << edgel.direction);
+          gegl_buffer_set (mask, GEGL_RECTANGLE (edgel.x, edgel.y, 1, 1), 0,
+                           NULL, &val, GEGL_AUTO_ROWSTRIDE);
+        }
+      if (gimp_edgel_cmp (&edgel, &start) != 0)
+        ++count;
+    }
+  while (gimp_edgel_cmp (&edgel, &start) != 0 && count <= size_limit);
+
+  return count;
+}
+
+/**
+ * gimp_edgel_region_area:
+ * @mask: current state of closed line art buffer.
+ * @start_edgel: edgel to follow.
+ *
+ * Follows a line border, starting from @start_edgel to compute the area
+ * enclosed by this border.
+ * Unfortunately this may return a negative area when the line does not
+ * close a zone. In this case, there is an uncertaincy on the size of
+ * the created zone, and we should consider it a big size.
+ *
+ * Returns: the area enclosed by the followed line, or a negative value
+ * if the zone is not closed (hence actual area unknown).
+ */
+static glong
+gimp_edgel_region_area (const GeglBuffer *mask,
+                        Edgel             start_edgel)
+{
+  Edgel edgel = start_edgel;
+  glong area = 0;
+
+  do
+    {
+      if (edgel.direction == XPlusDirection)
+        area -= edgel.x;
+      else if (edgel.direction == XMinusDirection)
+        area += edgel.x - 1;
+
+      gimp_edgelset_next8 (mask, &edgel, &edgel);
+    }
+  while (gimp_edgel_cmp (&edgel, &start_edgel) != 0);
+
+  return area;
+}
+
+/* Edgel sets */
+
+static GArray *
+gimp_edgelset_new (GeglBuffer *buffer,
+                   GimpAsync  *async)
+{
+  GeglBufferIterator *gi;
+  GArray             *set;
+  GHashTable         *edgel2index;
+  gint                width  = gegl_buffer_get_width (buffer);
+  gint                height = gegl_buffer_get_height (buffer);
+
+  set = g_array_new (TRUE, TRUE, sizeof (Edgel *));
+  g_array_set_clear_func (set, (GDestroyNotify) gimp_edgel_clear);
+
+  if (width <= 1 || height <= 1)
+    return set;
+
+  edgel2index = g_hash_table_new ((GHashFunc) edgel2index_hash_fun,
+                                  (GEqualFunc) edgel2index_equal_fun);
+
+  gi = gegl_buffer_iterator_new (buffer, GEGL_RECTANGLE (0, 0, width, height),
+                                 0, NULL, GEGL_ACCESS_READ, GEGL_ABYSS_NONE, 5);
+  gegl_buffer_iterator_add (gi, buffer, GEGL_RECTANGLE (0, -1, width, height),
+                            0, NULL, GEGL_ACCESS_READ, GEGL_ABYSS_NONE);
+  gegl_buffer_iterator_add (gi, buffer, GEGL_RECTANGLE (0, 1, width, height),
+                            0, NULL, GEGL_ACCESS_READ, GEGL_ABYSS_NONE);
+  gegl_buffer_iterator_add (gi, buffer, GEGL_RECTANGLE (-1, 0, width, height),
+                            0, NULL, GEGL_ACCESS_READ, GEGL_ABYSS_NONE);
+  gegl_buffer_iterator_add (gi, buffer, GEGL_RECTANGLE (1, 0, width, height),
+                            0, NULL, GEGL_ACCESS_READ, GEGL_ABYSS_NONE);
+  while (gegl_buffer_iterator_next (gi))
+    {
+      guint8 *p      = (guint8*) gi->items[0].data;
+      guint8 *prevy  = (guint8*) gi->items[1].data;
+      guint8 *nexty  = (guint8*) gi->items[2].data;
+      guint8 *prevx  = (guint8*) gi->items[3].data;
+      guint8 *nextx  = (guint8*) gi->items[4].data;
+      gint    startx = gi->items[0].roi.x;
+      gint    starty = gi->items[0].roi.y;
+      gint    endy   = starty + gi->items[0].roi.height;
+      gint    endx   = startx + gi->items[0].roi.width;
+      gint    x;
+      gint    y;
+
+      if (gimp_async_is_canceled (async))
+        {
+          gegl_buffer_iterator_stop (gi);
+
+          gimp_async_abort (async);
+
+          goto end;
+        }
+
+      for (y = starty; y < endy; y++)
+        for (x = startx; x < endx; x++)
+          {
+            if (*(p++))
+              {
+                if (! *prevy)
+                  gimp_edgelset_add (set, x, y, YMinusDirection, edgel2index);
+                if (! *nexty)
+                  gimp_edgelset_add (set, x, y, YPlusDirection, edgel2index);
+                if (! *prevx)
+                  gimp_edgelset_add (set, x, y, XMinusDirection, edgel2index);
+                if (! *nextx)
+                  gimp_edgelset_add (set, x, y, XPlusDirection, edgel2index);
+              }
+            prevy++;
+            nexty++;
+            prevx++;
+            nextx++;
+          }
+    }
+
+  gimp_edgelset_build_graph (set, buffer, edgel2index, async);
+  if (gimp_async_is_stopped (async))
+    goto end;
+
+  gimp_edgelset_init_normals (set);
+
+ end:
+  g_hash_table_destroy (edgel2index);
+
+  if (gimp_async_is_stopped (async))
+    {
+      g_array_free (set, TRUE);
+      set = NULL;
+    }
+
+  return set;
+}
+
+static void
+gimp_edgelset_add (GArray     *set,
+                   int         x,
+                   int         y,
+                   Direction   direction,
+                   GHashTable *edgel2index)
+{
+  Edgel         *edgel    = gimp_edgel_new (x, y, direction);
+  unsigned long  position = set->len;
+
+  g_array_append_val (set, edgel);
+  g_hash_table_insert (edgel2index, edgel, GUINT_TO_POINTER (position));
+}
+
+static void
+gimp_edgelset_init_normals (GArray *set)
+{
+  Edgel **e = (Edgel**) set->data;
+
+  while (*e)
+    {
+      GimpVector2 n = Direction2Normal[(*e)->direction];
+
+      (*e)->x_normal = n.x;
+      (*e)->y_normal = n.y;
+      e++;
+    }
+}
+
+static void
+gimp_edgelset_smooth_normals (GArray    *set,
+                              int        mask_size,
+                              GimpAsync *async)
+{
+  const gfloat sigma = mask_size * 0.775;
+  const gfloat den   = 2 * sigma * sigma;
+  gfloat       weights[65];
+  GimpVector2  smoothed_normal;
+  gint         i;
+
+  gimp_assert (mask_size <= 65);
+
+  weights[0] = 1.0f;
+  for (int i = 1; i <= mask_size; ++i)
+    weights[i] = expf (-(i * i) / den);
+
+  for (i = 0; i < set->len; i++)
+    {
+      Edgel *it           = g_array_index (set, Edgel*, i);
+      Edgel *edgel_before = g_array_index (set, Edgel*, it->previous);
+      Edgel *edgel_after  = g_array_index (set, Edgel*, it->next);
+      int    n = mask_size;
+      int    i = 1;
+
+      if (gimp_async_is_canceled (async))
+        {
+          gimp_async_abort (async);
+
+          return;
+        }
+
+      smoothed_normal = Direction2Normal[it->direction];
+      while (n-- && (edgel_after != edgel_before))
+        {
+          smoothed_normal = gimp_vector2_add_val (smoothed_normal,
+                                                  gimp_vector2_mul_val (Direction2Normal[edgel_before->direction], weights[i]));
+          smoothed_normal = gimp_vector2_add_val (smoothed_normal,
+                                                  gimp_vector2_mul_val (Direction2Normal[edgel_after->direction], weights[i]));
+          edgel_before = g_array_index (set, Edgel *, edgel_before->previous);
+          edgel_after  = g_array_index (set, Edgel *, edgel_after->next);
+          ++i;
+        }
+      gimp_vector2_normalize (&smoothed_normal);
+      it->x_normal = smoothed_normal.x;
+      it->y_normal = smoothed_normal.y;
+    }
+}
+
+static void
+gimp_edgelset_compute_curvature (GArray    *set,
+                                 GimpAsync *async)
+{
+  gint i;
+
+  for (i = 0; i < set->len; i++)
+    {
+      Edgel       *it       = g_array_index (set, Edgel*, i);
+      Edgel       *previous = g_array_index (set, Edgel *, it->previous);
+      Edgel       *next     = g_array_index (set, Edgel *, it->next);
+      GimpVector2  n_prev   = gimp_vector2_new (previous->x_normal, previous->y_normal);
+      GimpVector2  n_next   = gimp_vector2_new (next->x_normal, next->y_normal);
+      GimpVector2  diff     = gimp_vector2_mul_val (gimp_vector2_sub_val (n_next, n_prev),
+                                                    0.5);
+      const float  c        = gimp_vector2_length_val (diff);
+      const float  crossp   = n_prev.x * n_next.y - n_prev.y * n_next.x;
+
+      it->curvature = (crossp > 0.0f) ? c : -c;
+
+      if (gimp_async_is_canceled (async))
+        {
+          gimp_async_abort (async);
+
+          return;
+        }
+    }
+}
+
+static void
+gimp_edgelset_build_graph (GArray     *set,
+                           GeglBuffer *buffer,
+                           GHashTable *edgel2index,
+                           GimpAsync  *async)
+{
+  Edgel edgel;
+  gint  i;
+
+  for (i = 0; i < set->len; i++)
+    {
+      Edgel *neighbor;
+      Edgel *it = g_array_index (set, Edgel *, i);
+      guint  neighbor_pos;
+
+      if (gimp_async_is_canceled (async))
+        {
+          gimp_async_abort (async);
+
+          return;
+        }
+
+      gimp_edgelset_next8 (buffer, it, &edgel);
+
+      gimp_assert (g_hash_table_contains (edgel2index, &edgel));
+      neighbor_pos = GPOINTER_TO_UINT (g_hash_table_lookup (edgel2index, &edgel));
+      it->next = neighbor_pos;
+      neighbor = g_array_index (set, Edgel *, neighbor_pos);
+      neighbor->previous = i;
+    }
+}
+
+static void
+gimp_edgelset_next8 (const GeglBuffer *buffer,
+                     Edgel            *it,
+                     Edgel            *n)
+{
+  guint8 pixels[9];
+
+  n->x         = it->x;
+  n->y         = it->y;
+  n->direction = it->direction;
+
+  gegl_buffer_get ((GeglBuffer *) buffer,
+                   GEGL_RECTANGLE (n->x - 1, n->y - 1, 3, 3),
+                   1.0, NULL, pixels, GEGL_AUTO_ROWSTRIDE,
+                   GEGL_ABYSS_NONE);
+  switch (n->direction)
+    {
+    case XPlusDirection:
+      if (pixels[8])
+        {
+          ++(n->y);
+          ++(n->x);
+          n->direction = YMinusDirection;
+        }
+      else if (pixels[7])
+        {
+          ++(n->y);
+        }
+      else
+        {
+          n->direction = YPlusDirection;
+        }
+      break;
+    case YMinusDirection:
+      if (pixels[2])
+        {
+          ++(n->x);
+          --(n->y);
+          n->direction = XMinusDirection;
+        }
+      else if (pixels[5])
+        {
+          ++(n->x);
+        }
+      else
+        {
+          n->direction = XPlusDirection;
+        }
+      break;
+    case XMinusDirection:
+      if (pixels[0])
+        {
+          --(n->x);
+          --(n->y);
+          n->direction = YPlusDirection;
+        }
+      else if (pixels[1])
+        {
+          --(n->y);
+        }
+      else
+        {
+          n->direction = YMinusDirection;
+        }
+      break;
+    case YPlusDirection:
+      if (pixels[6])
+        {
+          --(n->x);
+          ++(n->y);
+          n->direction = XPlusDirection;
+        }
+      else if (pixels[3])
+        {
+          --(n->x);
+        }
+      else
+        {
+          n->direction = XMinusDirection;
+        }
+      break;
+    default:
+      g_return_if_reached ();
+      break;
+    }
+}
diff --git a/app/core/gimplineart.h b/app/core/gimplineart.h
new file mode 100644
index 0000000..cdec1ee
--- /dev/null
+++ b/app/core/gimplineart.h
@@ -0,0 +1,73 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * Copyright (C) 2017 Sébastien Fourey & David Tchumperlé
+ * Copyright (C) 2018 Jehan
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_LINEART__
+#define __GIMP_LINEART__
+
+
+#include "gimpobject.h"
+
+#define GIMP_TYPE_LINE_ART            (gimp_line_art_get_type ())
+#define GIMP_LINE_ART(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_LINE_ART, GimpLineArt))
+#define GIMP_LINE_ART_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_LINE_ART, GimpLineArtClass))
+#define GIMP_IS_LINE_ART(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_LINE_ART))
+#define GIMP_IS_LINE_ART_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_LINE_ART))
+#define GIMP_LINE_ART_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_LINE_ART, GimpLineArtClass))
+
+
+typedef struct _GimpLineArtClass   GimpLineArtClass;
+typedef struct _GimpLineArtPrivate GimpLineArtPrivate;
+
+struct _GimpLineArt
+{
+  GimpObject          parent_instance;
+
+  GimpLineArtPrivate *priv;
+};
+
+struct _GimpLineArtClass
+{
+  GimpObjectClass     parent_class;
+
+  /* Signals */
+
+  void (* computing_start) (GimpLineArt *line_art);
+  void (* computing_end)   (GimpLineArt *line_art);
+};
+
+
+GType                gimp_line_art_get_type         (void) G_GNUC_CONST;
+
+GimpLineArt        * gimp_line_art_new              (void);
+
+void                 gimp_line_art_bind_gap_length  (GimpLineArt  *line_art,
+                                                     gboolean      bound);
+
+void                 gimp_line_art_set_input        (GimpLineArt  *line_art,
+                                                     GimpPickable *pickable);
+GimpPickable       * gimp_line_art_get_input        (GimpLineArt  *line_art);
+void                 gimp_line_art_freeze           (GimpLineArt  *line_art);
+void                 gimp_line_art_thaw             (GimpLineArt  *line_art);
+gboolean             gimp_line_art_is_frozen        (GimpLineArt  *line_art);
+
+GeglBuffer         * gimp_line_art_get              (GimpLineArt  *line_art,
+                                                     gfloat      **distmap);
+
+#endif /* __GIMP_LINEART__ */
diff --git a/app/core/gimplist.c b/app/core/gimplist.c
new file mode 100644
index 0000000..0fbca1f
--- /dev/null
+++ b/app/core/gimplist.c
@@ -0,0 +1,691 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1997 Spencer Kimball and Peter Mattis
+ *
+ * gimplist.c
+ * Copyright (C) 2001-2016 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <stdlib.h>
+#include <string.h> /* strcmp */
+
+#include <glib-object.h>
+
+#include "core-types.h"
+
+#include "gimp-memsize.h"
+#include "gimplist.h"
+
+
+enum
+{
+  PROP_0,
+  PROP_UNIQUE_NAMES,
+  PROP_SORT_FUNC,
+  PROP_APPEND
+};
+
+
+static void         gimp_list_finalize           (GObject                 *object);
+static void         gimp_list_set_property       (GObject                 *object,
+                                                  guint                    property_id,
+                                                  const GValue            *value,
+                                                  GParamSpec              *pspec);
+static void         gimp_list_get_property       (GObject                 *object,
+                                                  guint                    property_id,
+                                                  GValue                  *value,
+                                                  GParamSpec              *pspec);
+
+static gint64       gimp_list_get_memsize        (GimpObject              *object,
+                                                  gint64                  *gui_size);
+
+static void         gimp_list_add                (GimpContainer           *container,
+                                                  GimpObject              *object);
+static void         gimp_list_remove             (GimpContainer           *container,
+                                                  GimpObject              *object);
+static void         gimp_list_reorder            (GimpContainer           *container,
+                                                  GimpObject              *object,
+                                                  gint                     new_index);
+static void         gimp_list_clear              (GimpContainer           *container);
+static gboolean     gimp_list_have               (GimpContainer           *container,
+                                                  GimpObject              *object);
+static void         gimp_list_foreach            (GimpContainer           *container,
+                                                  GFunc                    func,
+                                                  gpointer                 user_data);
+static GimpObject * gimp_list_search             (GimpContainer           *container,
+                                                  GimpContainerSearchFunc  func,
+                                                  gpointer                 user_data);
+static gboolean     gimp_list_get_unique_names   (GimpContainer           *container);
+static GimpObject * gimp_list_get_child_by_name  (GimpContainer           *container,
+                                                  const gchar             *name);
+static GimpObject * gimp_list_get_child_by_index (GimpContainer           *container,
+                                                  gint                     index);
+static gint         gimp_list_get_child_index    (GimpContainer           *container,
+                                                  GimpObject              *object);
+
+static void         gimp_list_uniquefy_name      (GimpList                *gimp_list,
+                                                  GimpObject              *object);
+static void         gimp_list_object_renamed     (GimpObject              *object,
+                                                  GimpList                *list);
+
+
+G_DEFINE_TYPE (GimpList, gimp_list, GIMP_TYPE_CONTAINER)
+
+#define parent_class gimp_list_parent_class
+
+
+static void
+gimp_list_class_init (GimpListClass *klass)
+{
+  GObjectClass       *object_class      = G_OBJECT_CLASS (klass);
+  GimpObjectClass    *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+  GimpContainerClass *container_class   = GIMP_CONTAINER_CLASS (klass);
+
+  object_class->finalize              = gimp_list_finalize;
+  object_class->set_property          = gimp_list_set_property;
+  object_class->get_property          = gimp_list_get_property;
+
+  gimp_object_class->get_memsize      = gimp_list_get_memsize;
+
+  container_class->add                = gimp_list_add;
+  container_class->remove             = gimp_list_remove;
+  container_class->reorder            = gimp_list_reorder;
+  container_class->clear              = gimp_list_clear;
+  container_class->have               = gimp_list_have;
+  container_class->foreach            = gimp_list_foreach;
+  container_class->search             = gimp_list_search;
+  container_class->get_unique_names   = gimp_list_get_unique_names;
+  container_class->get_child_by_name  = gimp_list_get_child_by_name;
+  container_class->get_child_by_index = gimp_list_get_child_by_index;
+  container_class->get_child_index    = gimp_list_get_child_index;
+
+  g_object_class_install_property (object_class, PROP_UNIQUE_NAMES,
+                                   g_param_spec_boolean ("unique-names",
+                                                         NULL, NULL,
+                                                         FALSE,
+                                                         GIMP_PARAM_READWRITE |
+                                                         G_PARAM_CONSTRUCT_ONLY));
+
+  g_object_class_install_property (object_class, PROP_SORT_FUNC,
+                                   g_param_spec_pointer ("sort-func",
+                                                         NULL, NULL,
+                                                         GIMP_PARAM_READWRITE |
+                                                         G_PARAM_CONSTRUCT));
+
+  g_object_class_install_property (object_class, PROP_APPEND,
+                                   g_param_spec_boolean ("append",
+                                                         NULL, NULL,
+                                                         FALSE,
+                                                         GIMP_PARAM_READWRITE |
+                                                         G_PARAM_CONSTRUCT));
+}
+
+static void
+gimp_list_init (GimpList *list)
+{
+  list->queue        = g_queue_new ();
+  list->unique_names = FALSE;
+  list->sort_func    = NULL;
+  list->append       = FALSE;
+}
+
+static void
+gimp_list_finalize (GObject *object)
+{
+  GimpList *list = GIMP_LIST (object);
+
+  if (list->queue)
+    {
+      g_queue_free (list->queue);
+      list->queue = NULL;
+    }
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gimp_list_set_property (GObject      *object,
+                        guint         property_id,
+                        const GValue *value,
+                        GParamSpec   *pspec)
+{
+  GimpList *list = GIMP_LIST (object);
+
+  switch (property_id)
+    {
+    case PROP_UNIQUE_NAMES:
+      list->unique_names = g_value_get_boolean (value);
+      break;
+    case PROP_SORT_FUNC:
+      gimp_list_set_sort_func (list, g_value_get_pointer (value));
+      break;
+    case PROP_APPEND:
+      list->append = g_value_get_boolean (value);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_list_get_property (GObject    *object,
+                        guint       property_id,
+                        GValue     *value,
+                        GParamSpec *pspec)
+{
+  GimpList *list = GIMP_LIST (object);
+
+  switch (property_id)
+    {
+    case PROP_UNIQUE_NAMES:
+      g_value_set_boolean (value, list->unique_names);
+      break;
+    case PROP_SORT_FUNC:
+      g_value_set_pointer (value, list->sort_func);
+      break;
+    case PROP_APPEND:
+      g_value_set_boolean (value, list->append);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static gint64
+gimp_list_get_memsize (GimpObject *object,
+                       gint64     *gui_size)
+{
+  GimpList *list    = GIMP_LIST (object);
+  gint64    memsize = 0;
+
+  if (gimp_container_get_policy (GIMP_CONTAINER (list)) ==
+      GIMP_CONTAINER_POLICY_STRONG)
+    {
+      memsize += gimp_g_queue_get_memsize_foreach (list->queue,
+                                                   (GimpMemsizeFunc) gimp_object_get_memsize,
+                                                   gui_size);
+    }
+  else
+    {
+      memsize += gimp_g_queue_get_memsize (list->queue, 0);
+    }
+
+  return memsize + GIMP_OBJECT_CLASS (parent_class)->get_memsize (object,
+                                                                  gui_size);
+}
+
+static gint
+gimp_list_sort_func (gconstpointer a,
+                     gconstpointer b,
+                     gpointer      user_data)
+{
+  GCompareFunc func = user_data;
+
+  return func (a, b);
+}
+
+static void
+gimp_list_add (GimpContainer *container,
+               GimpObject    *object)
+{
+  GimpList *list = GIMP_LIST (container);
+
+  if (list->unique_names)
+    gimp_list_uniquefy_name (list, object);
+
+  if (list->unique_names || list->sort_func)
+    g_signal_connect (object, "name-changed",
+                      G_CALLBACK (gimp_list_object_renamed),
+                      list);
+
+  if (list->sort_func)
+    {
+      g_queue_insert_sorted (list->queue, object, gimp_list_sort_func,
+                             list->sort_func);
+    }
+  else if (list->append)
+    {
+      g_queue_push_tail (list->queue, object);
+    }
+  else
+    {
+      g_queue_push_head (list->queue, object);
+    }
+
+  GIMP_CONTAINER_CLASS (parent_class)->add (container, object);
+}
+
+static void
+gimp_list_remove (GimpContainer *container,
+                  GimpObject    *object)
+{
+  GimpList *list = GIMP_LIST (container);
+
+  if (list->unique_names || list->sort_func)
+    g_signal_handlers_disconnect_by_func (object,
+                                          gimp_list_object_renamed,
+                                          list);
+
+  g_queue_remove (list->queue, object);
+
+  GIMP_CONTAINER_CLASS (parent_class)->remove (container, object);
+}
+
+static void
+gimp_list_reorder (GimpContainer *container,
+                   GimpObject    *object,
+                   gint           new_index)
+{
+  GimpList *list = GIMP_LIST (container);
+
+  g_queue_remove (list->queue, object);
+
+  if (new_index == gimp_container_get_n_children (container) - 1)
+    g_queue_push_tail (list->queue, object);
+  else
+    g_queue_push_nth (list->queue, object, new_index);
+}
+
+static void
+gimp_list_clear (GimpContainer *container)
+{
+  GimpList *list = GIMP_LIST (container);
+
+  while (g_queue_peek_head (list->queue))
+    gimp_container_remove (container, g_queue_peek_head (list->queue));
+}
+
+static gboolean
+gimp_list_have (GimpContainer *container,
+                GimpObject    *object)
+{
+  GimpList *list = GIMP_LIST (container);
+
+  return g_queue_find (list->queue, object) ? TRUE : FALSE;
+}
+
+static void
+gimp_list_foreach (GimpContainer *container,
+                   GFunc          func,
+                   gpointer       user_data)
+{
+  GimpList *list = GIMP_LIST (container);
+
+  g_queue_foreach (list->queue, func, user_data);
+}
+
+static GimpObject *
+gimp_list_search (GimpContainer           *container,
+                  GimpContainerSearchFunc  func,
+                  gpointer                 user_data)
+{
+  GimpList *list = GIMP_LIST (container);
+  GList    *iter;
+
+  iter = list->queue->head;
+
+  while (iter)
+    {
+      GimpObject *object = iter->data;
+
+      iter = g_list_next (iter);
+
+      if (func (object, user_data))
+        return object;
+    }
+
+  return NULL;
+}
+
+static gboolean
+gimp_list_get_unique_names (GimpContainer *container)
+{
+  GimpList *list = GIMP_LIST (container);
+
+  return list->unique_names;
+}
+
+static GimpObject *
+gimp_list_get_child_by_name (GimpContainer *container,
+                             const gchar   *name)
+{
+  GimpList *list = GIMP_LIST (container);
+  GList    *glist;
+
+  for (glist = list->queue->head; glist; glist = g_list_next (glist))
+    {
+      GimpObject *object = glist->data;
+
+      if (! strcmp (gimp_object_get_name (object), name))
+        return object;
+    }
+
+  return NULL;
+}
+
+static GimpObject *
+gimp_list_get_child_by_index (GimpContainer *container,
+                              gint           index)
+{
+  GimpList *list = GIMP_LIST (container);
+
+  return g_queue_peek_nth (list->queue, index);
+}
+
+static gint
+gimp_list_get_child_index (GimpContainer *container,
+                           GimpObject    *object)
+{
+  GimpList *list = GIMP_LIST (container);
+
+  return g_queue_index (list->queue, (gpointer) object);
+}
+
+/**
+ * gimp_list_new:
+ * @children_type: the #GType of objects the list is going to hold
+ * @unique_names:  if the list should ensure that all its children
+ *                 have unique names.
+ *
+ * Creates a new #GimpList object. Since #GimpList is a #GimpContainer
+ * implementation, it holds GimpObjects. Thus @children_type must be
+ * GIMP_TYPE_OBJECT or a type derived from it.
+ *
+ * The returned list has the #GIMP_CONTAINER_POLICY_STRONG.
+ *
+ * Return value: a new #GimpList object
+ **/
+GimpContainer *
+gimp_list_new (GType    children_type,
+               gboolean unique_names)
+{
+  GimpList *list;
+
+  g_return_val_if_fail (g_type_is_a (children_type, GIMP_TYPE_OBJECT), NULL);
+
+  list = g_object_new (GIMP_TYPE_LIST,
+                       "children-type", children_type,
+                       "policy",        GIMP_CONTAINER_POLICY_STRONG,
+                       "unique-names",  unique_names ? TRUE : FALSE,
+                       NULL);
+
+  /* for debugging purposes only */
+  gimp_object_set_static_name (GIMP_OBJECT (list), g_type_name (children_type));
+
+  return GIMP_CONTAINER (list);
+}
+
+/**
+ * gimp_list_new_weak:
+ * @children_type: the #GType of objects the list is going to hold
+ * @unique_names:  if the list should ensure that all its children
+ *                 have unique names.
+ *
+ * Creates a new #GimpList object. Since #GimpList is a #GimpContainer
+ * implementation, it holds GimpObjects. Thus @children_type must be
+ * GIMP_TYPE_OBJECT or a type derived from it.
+ *
+ * The returned list has the #GIMP_CONTAINER_POLICY_WEAK.
+ *
+ * Return value: a new #GimpList object
+ **/
+GimpContainer *
+gimp_list_new_weak (GType    children_type,
+                    gboolean unique_names)
+{
+  GimpList *list;
+
+  g_return_val_if_fail (g_type_is_a (children_type, GIMP_TYPE_OBJECT), NULL);
+
+  list = g_object_new (GIMP_TYPE_LIST,
+                       "children-type", children_type,
+                       "policy",        GIMP_CONTAINER_POLICY_WEAK,
+                       "unique-names",  unique_names ? TRUE : FALSE,
+                       NULL);
+
+  /* for debugging purposes only */
+  gimp_object_set_static_name (GIMP_OBJECT (list), g_type_name (children_type));
+
+  return GIMP_CONTAINER (list);
+}
+
+/**
+ * gimp_list_reverse:
+ * @list: a #GimpList
+ *
+ * Reverses the order of elements in a #GimpList.
+ **/
+void
+gimp_list_reverse (GimpList *list)
+{
+  g_return_if_fail (GIMP_IS_LIST (list));
+
+  if (gimp_container_get_n_children (GIMP_CONTAINER (list)) > 1)
+    {
+      gimp_container_freeze (GIMP_CONTAINER (list));
+      g_queue_reverse (list->queue);
+      gimp_container_thaw (GIMP_CONTAINER (list));
+    }
+}
+
+/**
+ * gimp_list_set_sort_func:
+ * @list:      a #GimpList
+ * @sort_func: a #GCompareFunc
+ *
+ * Sorts the elements of @list using gimp_list_sort() and remembers the
+ * passed @sort_func in order to keep the list ordered across inserting
+ * or renaming children.
+ **/
+void
+gimp_list_set_sort_func (GimpList     *list,
+                         GCompareFunc  sort_func)
+{
+  g_return_if_fail (GIMP_IS_LIST (list));
+
+  if (sort_func != list->sort_func)
+    {
+      if (sort_func)
+        gimp_list_sort (list, sort_func);
+
+      list->sort_func = sort_func;
+      g_object_notify (G_OBJECT (list), "sort-func");
+    }
+}
+
+/**
+ * gimp_list_get_sort_func:
+ * @list: a #GimpList
+ *
+ * Returns the @list's sort function, see gimp_list_set_sort_func().
+ *
+ * Return Value: The @list's sort function.
+ **/
+GCompareFunc
+gimp_list_get_sort_func (GimpList*list)
+{
+  g_return_val_if_fail (GIMP_IS_LIST (list), NULL);
+
+  return list->sort_func;
+}
+
+/**
+ * gimp_list_sort:
+ * @list: a #GimpList
+ * @sort_func: a #GCompareFunc
+ *
+ * Sorts the elements of a #GimpList according to the given @sort_func.
+ * See g_list_sort() for a detailed description of this function.
+ **/
+void
+gimp_list_sort (GimpList     *list,
+                GCompareFunc  sort_func)
+{
+  g_return_if_fail (GIMP_IS_LIST (list));
+  g_return_if_fail (sort_func != NULL);
+
+  if (gimp_container_get_n_children (GIMP_CONTAINER (list)) > 1)
+    {
+      gimp_container_freeze (GIMP_CONTAINER (list));
+      g_queue_sort (list->queue, gimp_list_sort_func, sort_func);
+      gimp_container_thaw (GIMP_CONTAINER (list));
+    }
+}
+
+/**
+ * gimp_list_sort_by_name:
+ * @list: a #GimpList
+ *
+ * Sorts the #GimpObject elements of a #GimpList by their names.
+ **/
+void
+gimp_list_sort_by_name (GimpList *list)
+{
+  g_return_if_fail (GIMP_IS_LIST (list));
+
+  gimp_list_sort (list, (GCompareFunc) gimp_object_name_collate);
+}
+
+
+/*  private functions  */
+
+static void
+gimp_list_uniquefy_name (GimpList   *gimp_list,
+                         GimpObject *object)
+{
+  gchar *name = (gchar *) gimp_object_get_name (object);
+  GList *list;
+
+  if (! name)
+    return;
+
+  for (list = gimp_list->queue->head; list; list = g_list_next (list))
+    {
+      GimpObject  *object2 = list->data;
+      const gchar *name2   = gimp_object_get_name (object2);
+
+      if (object != object2 &&
+          name2             &&
+          ! strcmp (name, name2))
+        break;
+    }
+
+  if (list)
+    {
+      gchar *ext;
+      gchar *new_name   = NULL;
+      gint   unique_ext = 0;
+
+      name = g_strdup (name);
+
+      ext = strrchr (name, '#');
+
+      if (ext)
+        {
+          gchar ext_str[8];
+
+          unique_ext = atoi (ext + 1);
+
+          g_snprintf (ext_str, sizeof (ext_str), "%d", unique_ext);
+
+          /*  check if the extension really is of the form "#<n>"  */
+          if (! strcmp (ext_str, ext + 1))
+            {
+              if (ext > name && *(ext - 1) == ' ')
+                ext--;
+
+              *ext = '\0';
+            }
+          else
+            {
+              unique_ext = 0;
+            }
+        }
+
+      do
+        {
+          unique_ext++;
+
+          g_free (new_name);
+
+          new_name = g_strdup_printf ("%s #%d", name, unique_ext);
+
+          for (list = gimp_list->queue->head; list; list = g_list_next (list))
+            {
+              GimpObject  *object2 = list->data;
+              const gchar *name2   = gimp_object_get_name (object2);
+
+              if (object != object2 &&
+                  name2             &&
+                  ! strcmp (new_name, name2))
+                break;
+            }
+        }
+      while (list);
+
+      g_free (name);
+
+      gimp_object_take_name (object, new_name);
+    }
+}
+
+static void
+gimp_list_object_renamed (GimpObject *object,
+                          GimpList   *list)
+{
+  if (list->unique_names)
+    {
+      g_signal_handlers_block_by_func (object,
+                                       gimp_list_object_renamed,
+                                       list);
+
+      gimp_list_uniquefy_name (list, object);
+
+      g_signal_handlers_unblock_by_func (object,
+                                         gimp_list_object_renamed,
+                                         list);
+    }
+
+  if (list->sort_func)
+    {
+      GList *glist;
+      gint   old_index;
+      gint   new_index = 0;
+
+      old_index = g_queue_index (list->queue, object);
+
+      for (glist = list->queue->head; glist; glist = g_list_next (glist))
+        {
+          GimpObject *object2 = GIMP_OBJECT (glist->data);
+
+          if (object == object2)
+            continue;
+
+          if (list->sort_func (object, object2) > 0)
+            new_index++;
+          else
+            break;
+        }
+
+      if (new_index != old_index)
+        gimp_container_reorder (GIMP_CONTAINER (list), object, new_index);
+    }
+}
diff --git a/app/core/gimplist.h b/app/core/gimplist.h
new file mode 100644
index 0000000..194493e
--- /dev/null
+++ b/app/core/gimplist.h
@@ -0,0 +1,70 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1997 Spencer Kimball and Peter Mattis
+ *
+ * gimplist.h
+ * Copyright (C) 2001-2016 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_LIST_H__
+#define __GIMP_LIST_H__
+
+
+#include "gimpcontainer.h"
+
+
+#define GIMP_TYPE_LIST            (gimp_list_get_type ())
+#define GIMP_LIST(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_LIST, GimpList))
+#define GIMP_LIST_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_LIST, GimpListClass))
+#define GIMP_IS_LIST(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_LIST))
+#define GIMP_IS_LIST_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_LIST))
+#define GIMP_LIST_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_LIST, GimpListClass))
+
+
+typedef struct _GimpListClass GimpListClass;
+
+struct _GimpList
+{
+  GimpContainer  parent_instance;
+
+  GQueue        *queue;
+  gboolean       unique_names;
+  GCompareFunc   sort_func;
+  gboolean       append;
+};
+
+struct _GimpListClass
+{
+  GimpContainerClass  parent_class;
+};
+
+
+GType           gimp_list_get_type      (void) G_GNUC_CONST;
+
+GimpContainer * gimp_list_new           (GType         children_type,
+                                         gboolean      unique_names);
+GimpContainer * gimp_list_new_weak      (GType         children_type,
+                                         gboolean      unique_names);
+
+void            gimp_list_reverse       (GimpList     *list);
+void            gimp_list_set_sort_func (GimpList     *list,
+                                         GCompareFunc  sort_func);
+GCompareFunc    gimp_list_get_sort_func (GimpList     *list);
+void            gimp_list_sort          (GimpList     *list,
+                                         GCompareFunc  sort_func);
+void            gimp_list_sort_by_name  (GimpList     *list);
+
+
+#endif  /* __GIMP_LIST_H__ */
diff --git a/app/core/gimpmarshal.c b/app/core/gimpmarshal.c
new file mode 100644
index 0000000..e4efb99
--- /dev/null
+++ b/app/core/gimpmarshal.c
@@ -0,0 +1,1901 @@
+/* This file is generated by glib-genmarshal, do not modify it. This code is licensed under the same license as the containing project. Note that it links to GLib, so must comply with the LGPL linking clauses. */
+#include <glib-object.h>
+
+#ifdef G_ENABLE_DEBUG
+#define g_marshal_value_peek_boolean(v)  g_value_get_boolean (v)
+#define g_marshal_value_peek_char(v)     g_value_get_schar (v)
+#define g_marshal_value_peek_uchar(v)    g_value_get_uchar (v)
+#define g_marshal_value_peek_int(v)      g_value_get_int (v)
+#define g_marshal_value_peek_uint(v)     g_value_get_uint (v)
+#define g_marshal_value_peek_long(v)     g_value_get_long (v)
+#define g_marshal_value_peek_ulong(v)    g_value_get_ulong (v)
+#define g_marshal_value_peek_int64(v)    g_value_get_int64 (v)
+#define g_marshal_value_peek_uint64(v)   g_value_get_uint64 (v)
+#define g_marshal_value_peek_enum(v)     g_value_get_enum (v)
+#define g_marshal_value_peek_flags(v)    g_value_get_flags (v)
+#define g_marshal_value_peek_float(v)    g_value_get_float (v)
+#define g_marshal_value_peek_double(v)   g_value_get_double (v)
+#define g_marshal_value_peek_string(v)   (char*) g_value_get_string (v)
+#define g_marshal_value_peek_param(v)    g_value_get_param (v)
+#define g_marshal_value_peek_boxed(v)    g_value_get_boxed (v)
+#define g_marshal_value_peek_pointer(v)  g_value_get_pointer (v)
+#define g_marshal_value_peek_object(v)   g_value_get_object (v)
+#define g_marshal_value_peek_variant(v)  g_value_get_variant (v)
+#else /* !G_ENABLE_DEBUG */
+/* WARNING: This code accesses GValues directly, which is UNSUPPORTED API.
+ *          Do not access GValues directly in your code. Instead, use the
+ *          g_value_get_*() functions
+ */
+#define g_marshal_value_peek_boolean(v)  (v)->data[0].v_int
+#define g_marshal_value_peek_char(v)     (v)->data[0].v_int
+#define g_marshal_value_peek_uchar(v)    (v)->data[0].v_uint
+#define g_marshal_value_peek_int(v)      (v)->data[0].v_int
+#define g_marshal_value_peek_uint(v)     (v)->data[0].v_uint
+#define g_marshal_value_peek_long(v)     (v)->data[0].v_long
+#define g_marshal_value_peek_ulong(v)    (v)->data[0].v_ulong
+#define g_marshal_value_peek_int64(v)    (v)->data[0].v_int64
+#define g_marshal_value_peek_uint64(v)   (v)->data[0].v_uint64
+#define g_marshal_value_peek_enum(v)     (v)->data[0].v_long
+#define g_marshal_value_peek_flags(v)    (v)->data[0].v_ulong
+#define g_marshal_value_peek_float(v)    (v)->data[0].v_float
+#define g_marshal_value_peek_double(v)   (v)->data[0].v_double
+#define g_marshal_value_peek_string(v)   (v)->data[0].v_pointer
+#define g_marshal_value_peek_param(v)    (v)->data[0].v_pointer
+#define g_marshal_value_peek_boxed(v)    (v)->data[0].v_pointer
+#define g_marshal_value_peek_pointer(v)  (v)->data[0].v_pointer
+#define g_marshal_value_peek_object(v)   (v)->data[0].v_pointer
+#define g_marshal_value_peek_variant(v)  (v)->data[0].v_pointer
+#endif /* !G_ENABLE_DEBUG */
+
+/* BOOLEAN: BOOLEAN (../../../app/core/gimpmarshal.list:25) */
+/* Prototype for -Wmissing-prototypes */
+G_BEGIN_DECLS
+extern
+void gimp_marshal_BOOLEAN__BOOLEAN (GClosure     *closure,
+                                    GValue       *return_value,
+                                    guint         n_param_values,
+                                    const GValue *param_values,
+                                    gpointer      invocation_hint,
+                                    gpointer      marshal_data);
+G_END_DECLS
+void
+gimp_marshal_BOOLEAN__BOOLEAN (GClosure     *closure,
+                               GValue       *return_value,
+                               guint         n_param_values,
+                               const GValue *param_values,
+                               gpointer      invocation_hint G_GNUC_UNUSED,
+                               gpointer      marshal_data)
+{
+  typedef gboolean (*GMarshalFunc_BOOLEAN__BOOLEAN) (gpointer data1,
+                                                     gboolean arg1,
+                                                     gpointer data2);
+  GCClosure *cc = (GCClosure *) closure;
+  gpointer data1, data2;
+  GMarshalFunc_BOOLEAN__BOOLEAN callback;
+  gboolean v_return;
+
+  g_return_if_fail (return_value != NULL);
+  g_return_if_fail (n_param_values == 2);
+
+  if (G_CCLOSURE_SWAP_DATA (closure))
+    {
+      data1 = closure->data;
+      data2 = g_value_peek_pointer (param_values + 0);
+    }
+  else
+    {
+      data1 = g_value_peek_pointer (param_values + 0);
+      data2 = closure->data;
+    }
+  callback = (GMarshalFunc_BOOLEAN__BOOLEAN) (marshal_data ? marshal_data : cc->callback);
+
+  v_return = callback (data1,
+                       g_marshal_value_peek_boolean (param_values + 1),
+                       data2);
+
+  g_value_set_boolean (return_value, v_return);
+}
+
+/* BOOLEAN: DOUBLE (../../../app/core/gimpmarshal.list:26) */
+/* Prototype for -Wmissing-prototypes */
+G_BEGIN_DECLS
+extern
+void gimp_marshal_BOOLEAN__DOUBLE (GClosure     *closure,
+                                   GValue       *return_value,
+                                   guint         n_param_values,
+                                   const GValue *param_values,
+                                   gpointer      invocation_hint,
+                                   gpointer      marshal_data);
+G_END_DECLS
+void
+gimp_marshal_BOOLEAN__DOUBLE (GClosure     *closure,
+                              GValue       *return_value,
+                              guint         n_param_values,
+                              const GValue *param_values,
+                              gpointer      invocation_hint G_GNUC_UNUSED,
+                              gpointer      marshal_data)
+{
+  typedef gboolean (*GMarshalFunc_BOOLEAN__DOUBLE) (gpointer data1,
+                                                    gdouble arg1,
+                                                    gpointer data2);
+  GCClosure *cc = (GCClosure *) closure;
+  gpointer data1, data2;
+  GMarshalFunc_BOOLEAN__DOUBLE callback;
+  gboolean v_return;
+
+  g_return_if_fail (return_value != NULL);
+  g_return_if_fail (n_param_values == 2);
+
+  if (G_CCLOSURE_SWAP_DATA (closure))
+    {
+      data1 = closure->data;
+      data2 = g_value_peek_pointer (param_values + 0);
+    }
+  else
+    {
+      data1 = g_value_peek_pointer (param_values + 0);
+      data2 = closure->data;
+    }
+  callback = (GMarshalFunc_BOOLEAN__DOUBLE) (marshal_data ? marshal_data : cc->callback);
+
+  v_return = callback (data1,
+                       g_marshal_value_peek_double (param_values + 1),
+                       data2);
+
+  g_value_set_boolean (return_value, v_return);
+}
+
+/* BOOLEAN: ENUM, INT (../../../app/core/gimpmarshal.list:27) */
+/* Prototype for -Wmissing-prototypes */
+G_BEGIN_DECLS
+extern
+void gimp_marshal_BOOLEAN__ENUM_INT (GClosure     *closure,
+                                     GValue       *return_value,
+                                     guint         n_param_values,
+                                     const GValue *param_values,
+                                     gpointer      invocation_hint,
+                                     gpointer      marshal_data);
+G_END_DECLS
+void
+gimp_marshal_BOOLEAN__ENUM_INT (GClosure     *closure,
+                                GValue       *return_value,
+                                guint         n_param_values,
+                                const GValue *param_values,
+                                gpointer      invocation_hint G_GNUC_UNUSED,
+                                gpointer      marshal_data)
+{
+  typedef gboolean (*GMarshalFunc_BOOLEAN__ENUM_INT) (gpointer data1,
+                                                      gint arg1,
+                                                      gint arg2,
+                                                      gpointer data2);
+  GCClosure *cc = (GCClosure *) closure;
+  gpointer data1, data2;
+  GMarshalFunc_BOOLEAN__ENUM_INT callback;
+  gboolean v_return;
+
+  g_return_if_fail (return_value != NULL);
+  g_return_if_fail (n_param_values == 3);
+
+  if (G_CCLOSURE_SWAP_DATA (closure))
+    {
+      data1 = closure->data;
+      data2 = g_value_peek_pointer (param_values + 0);
+    }
+  else
+    {
+      data1 = g_value_peek_pointer (param_values + 0);
+      data2 = closure->data;
+    }
+  callback = (GMarshalFunc_BOOLEAN__ENUM_INT) (marshal_data ? marshal_data : cc->callback);
+
+  v_return = callback (data1,
+                       g_marshal_value_peek_enum (param_values + 1),
+                       g_marshal_value_peek_int (param_values + 2),
+                       data2);
+
+  g_value_set_boolean (return_value, v_return);
+}
+
+/* BOOLEAN: INT, UINT, ENUM (../../../app/core/gimpmarshal.list:28) */
+/* Prototype for -Wmissing-prototypes */
+G_BEGIN_DECLS
+extern
+void gimp_marshal_BOOLEAN__INT_UINT_ENUM (GClosure     *closure,
+                                          GValue       *return_value,
+                                          guint         n_param_values,
+                                          const GValue *param_values,
+                                          gpointer      invocation_hint,
+                                          gpointer      marshal_data);
+G_END_DECLS
+void
+gimp_marshal_BOOLEAN__INT_UINT_ENUM (GClosure     *closure,
+                                     GValue       *return_value,
+                                     guint         n_param_values,
+                                     const GValue *param_values,
+                                     gpointer      invocation_hint G_GNUC_UNUSED,
+                                     gpointer      marshal_data)
+{
+  typedef gboolean (*GMarshalFunc_BOOLEAN__INT_UINT_ENUM) (gpointer data1,
+                                                           gint arg1,
+                                                           guint arg2,
+                                                           gint arg3,
+                                                           gpointer data2);
+  GCClosure *cc = (GCClosure *) closure;
+  gpointer data1, data2;
+  GMarshalFunc_BOOLEAN__INT_UINT_ENUM callback;
+  gboolean v_return;
+
+  g_return_if_fail (return_value != NULL);
+  g_return_if_fail (n_param_values == 4);
+
+  if (G_CCLOSURE_SWAP_DATA (closure))
+    {
+      data1 = closure->data;
+      data2 = g_value_peek_pointer (param_values + 0);
+    }
+  else
+    {
+      data1 = g_value_peek_pointer (param_values + 0);
+      data2 = closure->data;
+    }
+  callback = (GMarshalFunc_BOOLEAN__INT_UINT_ENUM) (marshal_data ? marshal_data : cc->callback);
+
+  v_return = callback (data1,
+                       g_marshal_value_peek_int (param_values + 1),
+                       g_marshal_value_peek_uint (param_values + 2),
+                       g_marshal_value_peek_enum (param_values + 3),
+                       data2);
+
+  g_value_set_boolean (return_value, v_return);
+}
+
+/* BOOLEAN: OBJECT (../../../app/core/gimpmarshal.list:29) */
+/* Prototype for -Wmissing-prototypes */
+G_BEGIN_DECLS
+extern
+void gimp_marshal_BOOLEAN__OBJECT (GClosure     *closure,
+                                   GValue       *return_value,
+                                   guint         n_param_values,
+                                   const GValue *param_values,
+                                   gpointer      invocation_hint,
+                                   gpointer      marshal_data);
+G_END_DECLS
+void
+gimp_marshal_BOOLEAN__OBJECT (GClosure     *closure,
+                              GValue       *return_value,
+                              guint         n_param_values,
+                              const GValue *param_values,
+                              gpointer      invocation_hint G_GNUC_UNUSED,
+                              gpointer      marshal_data)
+{
+  typedef gboolean (*GMarshalFunc_BOOLEAN__OBJECT) (gpointer data1,
+                                                    gpointer arg1,
+                                                    gpointer data2);
+  GCClosure *cc = (GCClosure *) closure;
+  gpointer data1, data2;
+  GMarshalFunc_BOOLEAN__OBJECT callback;
+  gboolean v_return;
+
+  g_return_if_fail (return_value != NULL);
+  g_return_if_fail (n_param_values == 2);
+
+  if (G_CCLOSURE_SWAP_DATA (closure))
+    {
+      data1 = closure->data;
+      data2 = g_value_peek_pointer (param_values + 0);
+    }
+  else
+    {
+      data1 = g_value_peek_pointer (param_values + 0);
+      data2 = closure->data;
+    }
+  callback = (GMarshalFunc_BOOLEAN__OBJECT) (marshal_data ? marshal_data : cc->callback);
+
+  v_return = callback (data1,
+                       g_marshal_value_peek_object (param_values + 1),
+                       data2);
+
+  g_value_set_boolean (return_value, v_return);
+}
+
+/* BOOLEAN: OBJECT, POINTER (../../../app/core/gimpmarshal.list:30) */
+/* Prototype for -Wmissing-prototypes */
+G_BEGIN_DECLS
+extern
+void gimp_marshal_BOOLEAN__OBJECT_POINTER (GClosure     *closure,
+                                           GValue       *return_value,
+                                           guint         n_param_values,
+                                           const GValue *param_values,
+                                           gpointer      invocation_hint,
+                                           gpointer      marshal_data);
+G_END_DECLS
+void
+gimp_marshal_BOOLEAN__OBJECT_POINTER (GClosure     *closure,
+                                      GValue       *return_value,
+                                      guint         n_param_values,
+                                      const GValue *param_values,
+                                      gpointer      invocation_hint G_GNUC_UNUSED,
+                                      gpointer      marshal_data)
+{
+  typedef gboolean (*GMarshalFunc_BOOLEAN__OBJECT_POINTER) (gpointer data1,
+                                                            gpointer arg1,
+                                                            gpointer arg2,
+                                                            gpointer data2);
+  GCClosure *cc = (GCClosure *) closure;
+  gpointer data1, data2;
+  GMarshalFunc_BOOLEAN__OBJECT_POINTER callback;
+  gboolean v_return;
+
+  g_return_if_fail (return_value != NULL);
+  g_return_if_fail (n_param_values == 3);
+
+  if (G_CCLOSURE_SWAP_DATA (closure))
+    {
+      data1 = closure->data;
+      data2 = g_value_peek_pointer (param_values + 0);
+    }
+  else
+    {
+      data1 = g_value_peek_pointer (param_values + 0);
+      data2 = closure->data;
+    }
+  callback = (GMarshalFunc_BOOLEAN__OBJECT_POINTER) (marshal_data ? marshal_data : cc->callback);
+
+  v_return = callback (data1,
+                       g_marshal_value_peek_object (param_values + 1),
+                       g_marshal_value_peek_pointer (param_values + 2),
+                       data2);
+
+  g_value_set_boolean (return_value, v_return);
+}
+
+/* BOOLEAN: OBJECT, POINTER, STRING (../../../app/core/gimpmarshal.list:31) */
+/* Prototype for -Wmissing-prototypes */
+G_BEGIN_DECLS
+extern
+void gimp_marshal_BOOLEAN__OBJECT_POINTER_STRING (GClosure     *closure,
+                                                  GValue       *return_value,
+                                                  guint         n_param_values,
+                                                  const GValue *param_values,
+                                                  gpointer      invocation_hint,
+                                                  gpointer      marshal_data);
+G_END_DECLS
+void
+gimp_marshal_BOOLEAN__OBJECT_POINTER_STRING (GClosure     *closure,
+                                             GValue       *return_value,
+                                             guint         n_param_values,
+                                             const GValue *param_values,
+                                             gpointer      invocation_hint G_GNUC_UNUSED,
+                                             gpointer      marshal_data)
+{
+  typedef gboolean (*GMarshalFunc_BOOLEAN__OBJECT_POINTER_STRING) (gpointer data1,
+                                                                   gpointer arg1,
+                                                                   gpointer arg2,
+                                                                   gpointer arg3,
+                                                                   gpointer data2);
+  GCClosure *cc = (GCClosure *) closure;
+  gpointer data1, data2;
+  GMarshalFunc_BOOLEAN__OBJECT_POINTER_STRING callback;
+  gboolean v_return;
+
+  g_return_if_fail (return_value != NULL);
+  g_return_if_fail (n_param_values == 4);
+
+  if (G_CCLOSURE_SWAP_DATA (closure))
+    {
+      data1 = closure->data;
+      data2 = g_value_peek_pointer (param_values + 0);
+    }
+  else
+    {
+      data1 = g_value_peek_pointer (param_values + 0);
+      data2 = closure->data;
+    }
+  callback = (GMarshalFunc_BOOLEAN__OBJECT_POINTER_STRING) (marshal_data ? marshal_data : cc->callback);
+
+  v_return = callback (data1,
+                       g_marshal_value_peek_object (param_values + 1),
+                       g_marshal_value_peek_pointer (param_values + 2),
+                       g_marshal_value_peek_string (param_values + 3),
+                       data2);
+
+  g_value_set_boolean (return_value, v_return);
+}
+
+/* BOOLEAN: STRING (../../../app/core/gimpmarshal.list:32) */
+/* Prototype for -Wmissing-prototypes */
+G_BEGIN_DECLS
+extern
+void gimp_marshal_BOOLEAN__STRING (GClosure     *closure,
+                                   GValue       *return_value,
+                                   guint         n_param_values,
+                                   const GValue *param_values,
+                                   gpointer      invocation_hint,
+                                   gpointer      marshal_data);
+G_END_DECLS
+void
+gimp_marshal_BOOLEAN__STRING (GClosure     *closure,
+                              GValue       *return_value,
+                              guint         n_param_values,
+                              const GValue *param_values,
+                              gpointer      invocation_hint G_GNUC_UNUSED,
+                              gpointer      marshal_data)
+{
+  typedef gboolean (*GMarshalFunc_BOOLEAN__STRING) (gpointer data1,
+                                                    gpointer arg1,
+                                                    gpointer data2);
+  GCClosure *cc = (GCClosure *) closure;
+  gpointer data1, data2;
+  GMarshalFunc_BOOLEAN__STRING callback;
+  gboolean v_return;
+
+  g_return_if_fail (return_value != NULL);
+  g_return_if_fail (n_param_values == 2);
+
+  if (G_CCLOSURE_SWAP_DATA (closure))
+    {
+      data1 = closure->data;
+      data2 = g_value_peek_pointer (param_values + 0);
+    }
+  else
+    {
+      data1 = g_value_peek_pointer (param_values + 0);
+      data2 = closure->data;
+    }
+  callback = (GMarshalFunc_BOOLEAN__STRING) (marshal_data ? marshal_data : cc->callback);
+
+  v_return = callback (data1,
+                       g_marshal_value_peek_string (param_values + 1),
+                       data2);
+
+  g_value_set_boolean (return_value, v_return);
+}
+
+/* BOOLEAN: STRING, FLAGS (../../../app/core/gimpmarshal.list:33) */
+/* Prototype for -Wmissing-prototypes */
+G_BEGIN_DECLS
+extern
+void gimp_marshal_BOOLEAN__STRING_FLAGS (GClosure     *closure,
+                                         GValue       *return_value,
+                                         guint         n_param_values,
+                                         const GValue *param_values,
+                                         gpointer      invocation_hint,
+                                         gpointer      marshal_data);
+G_END_DECLS
+void
+gimp_marshal_BOOLEAN__STRING_FLAGS (GClosure     *closure,
+                                    GValue       *return_value,
+                                    guint         n_param_values,
+                                    const GValue *param_values,
+                                    gpointer      invocation_hint G_GNUC_UNUSED,
+                                    gpointer      marshal_data)
+{
+  typedef gboolean (*GMarshalFunc_BOOLEAN__STRING_FLAGS) (gpointer data1,
+                                                          gpointer arg1,
+                                                          guint arg2,
+                                                          gpointer data2);
+  GCClosure *cc = (GCClosure *) closure;
+  gpointer data1, data2;
+  GMarshalFunc_BOOLEAN__STRING_FLAGS callback;
+  gboolean v_return;
+
+  g_return_if_fail (return_value != NULL);
+  g_return_if_fail (n_param_values == 3);
+
+  if (G_CCLOSURE_SWAP_DATA (closure))
+    {
+      data1 = closure->data;
+      data2 = g_value_peek_pointer (param_values + 0);
+    }
+  else
+    {
+      data1 = g_value_peek_pointer (param_values + 0);
+      data2 = closure->data;
+    }
+  callback = (GMarshalFunc_BOOLEAN__STRING_FLAGS) (marshal_data ? marshal_data : cc->callback);
+
+  v_return = callback (data1,
+                       g_marshal_value_peek_string (param_values + 1),
+                       g_marshal_value_peek_flags (param_values + 2),
+                       data2);
+
+  g_value_set_boolean (return_value, v_return);
+}
+
+/* INT: DOUBLE (../../../app/core/gimpmarshal.list:35) */
+/* Prototype for -Wmissing-prototypes */
+G_BEGIN_DECLS
+extern
+void gimp_marshal_INT__DOUBLE (GClosure     *closure,
+                               GValue       *return_value,
+                               guint         n_param_values,
+                               const GValue *param_values,
+                               gpointer      invocation_hint,
+                               gpointer      marshal_data);
+G_END_DECLS
+void
+gimp_marshal_INT__DOUBLE (GClosure     *closure,
+                          GValue       *return_value,
+                          guint         n_param_values,
+                          const GValue *param_values,
+                          gpointer      invocation_hint G_GNUC_UNUSED,
+                          gpointer      marshal_data)
+{
+  typedef gint (*GMarshalFunc_INT__DOUBLE) (gpointer data1,
+                                            gdouble arg1,
+                                            gpointer data2);
+  GCClosure *cc = (GCClosure *) closure;
+  gpointer data1, data2;
+  GMarshalFunc_INT__DOUBLE callback;
+  gint v_return;
+
+  g_return_if_fail (return_value != NULL);
+  g_return_if_fail (n_param_values == 2);
+
+  if (G_CCLOSURE_SWAP_DATA (closure))
+    {
+      data1 = closure->data;
+      data2 = g_value_peek_pointer (param_values + 0);
+    }
+  else
+    {
+      data1 = g_value_peek_pointer (param_values + 0);
+      data2 = closure->data;
+    }
+  callback = (GMarshalFunc_INT__DOUBLE) (marshal_data ? marshal_data : cc->callback);
+
+  v_return = callback (data1,
+                       g_marshal_value_peek_double (param_values + 1),
+                       data2);
+
+  g_value_set_int (return_value, v_return);
+}
+
+/* VOID: BOOLEAN (../../../app/core/gimpmarshal.list:37) */
+#define gimp_marshal_VOID__BOOLEAN	g_cclosure_marshal_VOID__BOOLEAN
+
+/* VOID: BOOLEAN, INT, INT, INT, INT (../../../app/core/gimpmarshal.list:38) */
+/* Prototype for -Wmissing-prototypes */
+G_BEGIN_DECLS
+extern
+void gimp_marshal_VOID__BOOLEAN_INT_INT_INT_INT (GClosure     *closure,
+                                                 GValue       *return_value,
+                                                 guint         n_param_values,
+                                                 const GValue *param_values,
+                                                 gpointer      invocation_hint,
+                                                 gpointer      marshal_data);
+G_END_DECLS
+void
+gimp_marshal_VOID__BOOLEAN_INT_INT_INT_INT (GClosure     *closure,
+                                            GValue       *return_value G_GNUC_UNUSED,
+                                            guint         n_param_values,
+                                            const GValue *param_values,
+                                            gpointer      invocation_hint G_GNUC_UNUSED,
+                                            gpointer      marshal_data)
+{
+  typedef void (*GMarshalFunc_VOID__BOOLEAN_INT_INT_INT_INT) (gpointer data1,
+                                                              gboolean arg1,
+                                                              gint arg2,
+                                                              gint arg3,
+                                                              gint arg4,
+                                                              gint arg5,
+                                                              gpointer data2);
+  GCClosure *cc = (GCClosure *) closure;
+  gpointer data1, data2;
+  GMarshalFunc_VOID__BOOLEAN_INT_INT_INT_INT callback;
+
+  g_return_if_fail (n_param_values == 6);
+
+  if (G_CCLOSURE_SWAP_DATA (closure))
+    {
+      data1 = closure->data;
+      data2 = g_value_peek_pointer (param_values + 0);
+    }
+  else
+    {
+      data1 = g_value_peek_pointer (param_values + 0);
+      data2 = closure->data;
+    }
+  callback = (GMarshalFunc_VOID__BOOLEAN_INT_INT_INT_INT) (marshal_data ? marshal_data : cc->callback);
+
+  callback (data1,
+            g_marshal_value_peek_boolean (param_values + 1),
+            g_marshal_value_peek_int (param_values + 2),
+            g_marshal_value_peek_int (param_values + 3),
+            g_marshal_value_peek_int (param_values + 4),
+            g_marshal_value_peek_int (param_values + 5),
+            data2);
+}
+
+/* VOID: BOXED (../../../app/core/gimpmarshal.list:39) */
+#define gimp_marshal_VOID__BOXED	g_cclosure_marshal_VOID__BOXED
+
+/* VOID: BOXED, ENUM (../../../app/core/gimpmarshal.list:40) */
+/* Prototype for -Wmissing-prototypes */
+G_BEGIN_DECLS
+extern
+void gimp_marshal_VOID__BOXED_ENUM (GClosure     *closure,
+                                    GValue       *return_value,
+                                    guint         n_param_values,
+                                    const GValue *param_values,
+                                    gpointer      invocation_hint,
+                                    gpointer      marshal_data);
+G_END_DECLS
+void
+gimp_marshal_VOID__BOXED_ENUM (GClosure     *closure,
+                               GValue       *return_value G_GNUC_UNUSED,
+                               guint         n_param_values,
+                               const GValue *param_values,
+                               gpointer      invocation_hint G_GNUC_UNUSED,
+                               gpointer      marshal_data)
+{
+  typedef void (*GMarshalFunc_VOID__BOXED_ENUM) (gpointer data1,
+                                                 gpointer arg1,
+                                                 gint arg2,
+                                                 gpointer data2);
+  GCClosure *cc = (GCClosure *) closure;
+  gpointer data1, data2;
+  GMarshalFunc_VOID__BOXED_ENUM callback;
+
+  g_return_if_fail (n_param_values == 3);
+
+  if (G_CCLOSURE_SWAP_DATA (closure))
+    {
+      data1 = closure->data;
+      data2 = g_value_peek_pointer (param_values + 0);
+    }
+  else
+    {
+      data1 = g_value_peek_pointer (param_values + 0);
+      data2 = closure->data;
+    }
+  callback = (GMarshalFunc_VOID__BOXED_ENUM) (marshal_data ? marshal_data : cc->callback);
+
+  callback (data1,
+            g_marshal_value_peek_boxed (param_values + 1),
+            g_marshal_value_peek_enum (param_values + 2),
+            data2);
+}
+
+/* VOID: DOUBLE (../../../app/core/gimpmarshal.list:41) */
+#define gimp_marshal_VOID__DOUBLE	g_cclosure_marshal_VOID__DOUBLE
+
+/* VOID: DOUBLE, DOUBLE (../../../app/core/gimpmarshal.list:42) */
+/* Prototype for -Wmissing-prototypes */
+G_BEGIN_DECLS
+extern
+void gimp_marshal_VOID__DOUBLE_DOUBLE (GClosure     *closure,
+                                       GValue       *return_value,
+                                       guint         n_param_values,
+                                       const GValue *param_values,
+                                       gpointer      invocation_hint,
+                                       gpointer      marshal_data);
+G_END_DECLS
+void
+gimp_marshal_VOID__DOUBLE_DOUBLE (GClosure     *closure,
+                                  GValue       *return_value G_GNUC_UNUSED,
+                                  guint         n_param_values,
+                                  const GValue *param_values,
+                                  gpointer      invocation_hint G_GNUC_UNUSED,
+                                  gpointer      marshal_data)
+{
+  typedef void (*GMarshalFunc_VOID__DOUBLE_DOUBLE) (gpointer data1,
+                                                    gdouble arg1,
+                                                    gdouble arg2,
+                                                    gpointer data2);
+  GCClosure *cc = (GCClosure *) closure;
+  gpointer data1, data2;
+  GMarshalFunc_VOID__DOUBLE_DOUBLE callback;
+
+  g_return_if_fail (n_param_values == 3);
+
+  if (G_CCLOSURE_SWAP_DATA (closure))
+    {
+      data1 = closure->data;
+      data2 = g_value_peek_pointer (param_values + 0);
+    }
+  else
+    {
+      data1 = g_value_peek_pointer (param_values + 0);
+      data2 = closure->data;
+    }
+  callback = (GMarshalFunc_VOID__DOUBLE_DOUBLE) (marshal_data ? marshal_data : cc->callback);
+
+  callback (data1,
+            g_marshal_value_peek_double (param_values + 1),
+            g_marshal_value_peek_double (param_values + 2),
+            data2);
+}
+
+/* VOID: DOUBLE, DOUBLE, DOUBLE, DOUBLE (../../../app/core/gimpmarshal.list:43) */
+/* Prototype for -Wmissing-prototypes */
+G_BEGIN_DECLS
+extern
+void gimp_marshal_VOID__DOUBLE_DOUBLE_DOUBLE_DOUBLE (GClosure     *closure,
+                                                     GValue       *return_value,
+                                                     guint         n_param_values,
+                                                     const GValue *param_values,
+                                                     gpointer      invocation_hint,
+                                                     gpointer      marshal_data);
+G_END_DECLS
+void
+gimp_marshal_VOID__DOUBLE_DOUBLE_DOUBLE_DOUBLE (GClosure     *closure,
+                                                GValue       *return_value G_GNUC_UNUSED,
+                                                guint         n_param_values,
+                                                const GValue *param_values,
+                                                gpointer      invocation_hint G_GNUC_UNUSED,
+                                                gpointer      marshal_data)
+{
+  typedef void (*GMarshalFunc_VOID__DOUBLE_DOUBLE_DOUBLE_DOUBLE) (gpointer data1,
+                                                                  gdouble arg1,
+                                                                  gdouble arg2,
+                                                                  gdouble arg3,
+                                                                  gdouble arg4,
+                                                                  gpointer data2);
+  GCClosure *cc = (GCClosure *) closure;
+  gpointer data1, data2;
+  GMarshalFunc_VOID__DOUBLE_DOUBLE_DOUBLE_DOUBLE callback;
+
+  g_return_if_fail (n_param_values == 5);
+
+  if (G_CCLOSURE_SWAP_DATA (closure))
+    {
+      data1 = closure->data;
+      data2 = g_value_peek_pointer (param_values + 0);
+    }
+  else
+    {
+      data1 = g_value_peek_pointer (param_values + 0);
+      data2 = closure->data;
+    }
+  callback = (GMarshalFunc_VOID__DOUBLE_DOUBLE_DOUBLE_DOUBLE) (marshal_data ? marshal_data : cc->callback);
+
+  callback (data1,
+            g_marshal_value_peek_double (param_values + 1),
+            g_marshal_value_peek_double (param_values + 2),
+            g_marshal_value_peek_double (param_values + 3),
+            g_marshal_value_peek_double (param_values + 4),
+            data2);
+}
+
+/* VOID: ENUM (../../../app/core/gimpmarshal.list:44) */
+#define gimp_marshal_VOID__ENUM	g_cclosure_marshal_VOID__ENUM
+
+/* VOID: ENUM, INT (../../../app/core/gimpmarshal.list:45) */
+/* Prototype for -Wmissing-prototypes */
+G_BEGIN_DECLS
+extern
+void gimp_marshal_VOID__ENUM_INT (GClosure     *closure,
+                                  GValue       *return_value,
+                                  guint         n_param_values,
+                                  const GValue *param_values,
+                                  gpointer      invocation_hint,
+                                  gpointer      marshal_data);
+G_END_DECLS
+void
+gimp_marshal_VOID__ENUM_INT (GClosure     *closure,
+                             GValue       *return_value G_GNUC_UNUSED,
+                             guint         n_param_values,
+                             const GValue *param_values,
+                             gpointer      invocation_hint G_GNUC_UNUSED,
+                             gpointer      marshal_data)
+{
+  typedef void (*GMarshalFunc_VOID__ENUM_INT) (gpointer data1,
+                                               gint arg1,
+                                               gint arg2,
+                                               gpointer data2);
+  GCClosure *cc = (GCClosure *) closure;
+  gpointer data1, data2;
+  GMarshalFunc_VOID__ENUM_INT callback;
+
+  g_return_if_fail (n_param_values == 3);
+
+  if (G_CCLOSURE_SWAP_DATA (closure))
+    {
+      data1 = closure->data;
+      data2 = g_value_peek_pointer (param_values + 0);
+    }
+  else
+    {
+      data1 = g_value_peek_pointer (param_values + 0);
+      data2 = closure->data;
+    }
+  callback = (GMarshalFunc_VOID__ENUM_INT) (marshal_data ? marshal_data : cc->callback);
+
+  callback (data1,
+            g_marshal_value_peek_enum (param_values + 1),
+            g_marshal_value_peek_int (param_values + 2),
+            data2);
+}
+
+/* VOID: ENUM, INT, BOOLEAN (../../../app/core/gimpmarshal.list:46) */
+/* Prototype for -Wmissing-prototypes */
+G_BEGIN_DECLS
+extern
+void gimp_marshal_VOID__ENUM_INT_BOOLEAN (GClosure     *closure,
+                                          GValue       *return_value,
+                                          guint         n_param_values,
+                                          const GValue *param_values,
+                                          gpointer      invocation_hint,
+                                          gpointer      marshal_data);
+G_END_DECLS
+void
+gimp_marshal_VOID__ENUM_INT_BOOLEAN (GClosure     *closure,
+                                     GValue       *return_value G_GNUC_UNUSED,
+                                     guint         n_param_values,
+                                     const GValue *param_values,
+                                     gpointer      invocation_hint G_GNUC_UNUSED,
+                                     gpointer      marshal_data)
+{
+  typedef void (*GMarshalFunc_VOID__ENUM_INT_BOOLEAN) (gpointer data1,
+                                                       gint arg1,
+                                                       gint arg2,
+                                                       gboolean arg3,
+                                                       gpointer data2);
+  GCClosure *cc = (GCClosure *) closure;
+  gpointer data1, data2;
+  GMarshalFunc_VOID__ENUM_INT_BOOLEAN callback;
+
+  g_return_if_fail (n_param_values == 4);
+
+  if (G_CCLOSURE_SWAP_DATA (closure))
+    {
+      data1 = closure->data;
+      data2 = g_value_peek_pointer (param_values + 0);
+    }
+  else
+    {
+      data1 = g_value_peek_pointer (param_values + 0);
+      data2 = closure->data;
+    }
+  callback = (GMarshalFunc_VOID__ENUM_INT_BOOLEAN) (marshal_data ? marshal_data : cc->callback);
+
+  callback (data1,
+            g_marshal_value_peek_enum (param_values + 1),
+            g_marshal_value_peek_int (param_values + 2),
+            g_marshal_value_peek_boolean (param_values + 3),
+            data2);
+}
+
+/* VOID: ENUM, OBJECT (../../../app/core/gimpmarshal.list:47) */
+/* Prototype for -Wmissing-prototypes */
+G_BEGIN_DECLS
+extern
+void gimp_marshal_VOID__ENUM_OBJECT (GClosure     *closure,
+                                     GValue       *return_value,
+                                     guint         n_param_values,
+                                     const GValue *param_values,
+                                     gpointer      invocation_hint,
+                                     gpointer      marshal_data);
+G_END_DECLS
+void
+gimp_marshal_VOID__ENUM_OBJECT (GClosure     *closure,
+                                GValue       *return_value G_GNUC_UNUSED,
+                                guint         n_param_values,
+                                const GValue *param_values,
+                                gpointer      invocation_hint G_GNUC_UNUSED,
+                                gpointer      marshal_data)
+{
+  typedef void (*GMarshalFunc_VOID__ENUM_OBJECT) (gpointer data1,
+                                                  gint arg1,
+                                                  gpointer arg2,
+                                                  gpointer data2);
+  GCClosure *cc = (GCClosure *) closure;
+  gpointer data1, data2;
+  GMarshalFunc_VOID__ENUM_OBJECT callback;
+
+  g_return_if_fail (n_param_values == 3);
+
+  if (G_CCLOSURE_SWAP_DATA (closure))
+    {
+      data1 = closure->data;
+      data2 = g_value_peek_pointer (param_values + 0);
+    }
+  else
+    {
+      data1 = g_value_peek_pointer (param_values + 0);
+      data2 = closure->data;
+    }
+  callback = (GMarshalFunc_VOID__ENUM_OBJECT) (marshal_data ? marshal_data : cc->callback);
+
+  callback (data1,
+            g_marshal_value_peek_enum (param_values + 1),
+            g_marshal_value_peek_object (param_values + 2),
+            data2);
+}
+
+/* VOID: ENUM, POINTER (../../../app/core/gimpmarshal.list:48) */
+/* Prototype for -Wmissing-prototypes */
+G_BEGIN_DECLS
+extern
+void gimp_marshal_VOID__ENUM_POINTER (GClosure     *closure,
+                                      GValue       *return_value,
+                                      guint         n_param_values,
+                                      const GValue *param_values,
+                                      gpointer      invocation_hint,
+                                      gpointer      marshal_data);
+G_END_DECLS
+void
+gimp_marshal_VOID__ENUM_POINTER (GClosure     *closure,
+                                 GValue       *return_value G_GNUC_UNUSED,
+                                 guint         n_param_values,
+                                 const GValue *param_values,
+                                 gpointer      invocation_hint G_GNUC_UNUSED,
+                                 gpointer      marshal_data)
+{
+  typedef void (*GMarshalFunc_VOID__ENUM_POINTER) (gpointer data1,
+                                                   gint arg1,
+                                                   gpointer arg2,
+                                                   gpointer data2);
+  GCClosure *cc = (GCClosure *) closure;
+  gpointer data1, data2;
+  GMarshalFunc_VOID__ENUM_POINTER callback;
+
+  g_return_if_fail (n_param_values == 3);
+
+  if (G_CCLOSURE_SWAP_DATA (closure))
+    {
+      data1 = closure->data;
+      data2 = g_value_peek_pointer (param_values + 0);
+    }
+  else
+    {
+      data1 = g_value_peek_pointer (param_values + 0);
+      data2 = closure->data;
+    }
+  callback = (GMarshalFunc_VOID__ENUM_POINTER) (marshal_data ? marshal_data : cc->callback);
+
+  callback (data1,
+            g_marshal_value_peek_enum (param_values + 1),
+            g_marshal_value_peek_pointer (param_values + 2),
+            data2);
+}
+
+/* VOID: FLAGS (../../../app/core/gimpmarshal.list:49) */
+#define gimp_marshal_VOID__FLAGS	g_cclosure_marshal_VOID__FLAGS
+
+/* VOID: INT (../../../app/core/gimpmarshal.list:50) */
+#define gimp_marshal_VOID__INT	g_cclosure_marshal_VOID__INT
+
+/* VOID: INT, BOOLEAN (../../../app/core/gimpmarshal.list:51) */
+/* Prototype for -Wmissing-prototypes */
+G_BEGIN_DECLS
+extern
+void gimp_marshal_VOID__INT_BOOLEAN (GClosure     *closure,
+                                     GValue       *return_value,
+                                     guint         n_param_values,
+                                     const GValue *param_values,
+                                     gpointer      invocation_hint,
+                                     gpointer      marshal_data);
+G_END_DECLS
+void
+gimp_marshal_VOID__INT_BOOLEAN (GClosure     *closure,
+                                GValue       *return_value G_GNUC_UNUSED,
+                                guint         n_param_values,
+                                const GValue *param_values,
+                                gpointer      invocation_hint G_GNUC_UNUSED,
+                                gpointer      marshal_data)
+{
+  typedef void (*GMarshalFunc_VOID__INT_BOOLEAN) (gpointer data1,
+                                                  gint arg1,
+                                                  gboolean arg2,
+                                                  gpointer data2);
+  GCClosure *cc = (GCClosure *) closure;
+  gpointer data1, data2;
+  GMarshalFunc_VOID__INT_BOOLEAN callback;
+
+  g_return_if_fail (n_param_values == 3);
+
+  if (G_CCLOSURE_SWAP_DATA (closure))
+    {
+      data1 = closure->data;
+      data2 = g_value_peek_pointer (param_values + 0);
+    }
+  else
+    {
+      data1 = g_value_peek_pointer (param_values + 0);
+      data2 = closure->data;
+    }
+  callback = (GMarshalFunc_VOID__INT_BOOLEAN) (marshal_data ? marshal_data : cc->callback);
+
+  callback (data1,
+            g_marshal_value_peek_int (param_values + 1),
+            g_marshal_value_peek_boolean (param_values + 2),
+            data2);
+}
+
+/* VOID: INT, INT (../../../app/core/gimpmarshal.list:52) */
+/* Prototype for -Wmissing-prototypes */
+G_BEGIN_DECLS
+extern
+void gimp_marshal_VOID__INT_INT (GClosure     *closure,
+                                 GValue       *return_value,
+                                 guint         n_param_values,
+                                 const GValue *param_values,
+                                 gpointer      invocation_hint,
+                                 gpointer      marshal_data);
+G_END_DECLS
+void
+gimp_marshal_VOID__INT_INT (GClosure     *closure,
+                            GValue       *return_value G_GNUC_UNUSED,
+                            guint         n_param_values,
+                            const GValue *param_values,
+                            gpointer      invocation_hint G_GNUC_UNUSED,
+                            gpointer      marshal_data)
+{
+  typedef void (*GMarshalFunc_VOID__INT_INT) (gpointer data1,
+                                              gint arg1,
+                                              gint arg2,
+                                              gpointer data2);
+  GCClosure *cc = (GCClosure *) closure;
+  gpointer data1, data2;
+  GMarshalFunc_VOID__INT_INT callback;
+
+  g_return_if_fail (n_param_values == 3);
+
+  if (G_CCLOSURE_SWAP_DATA (closure))
+    {
+      data1 = closure->data;
+      data2 = g_value_peek_pointer (param_values + 0);
+    }
+  else
+    {
+      data1 = g_value_peek_pointer (param_values + 0);
+      data2 = closure->data;
+    }
+  callback = (GMarshalFunc_VOID__INT_INT) (marshal_data ? marshal_data : cc->callback);
+
+  callback (data1,
+            g_marshal_value_peek_int (param_values + 1),
+            g_marshal_value_peek_int (param_values + 2),
+            data2);
+}
+
+/* VOID: INT, INT, INT, INT (../../../app/core/gimpmarshal.list:53) */
+/* Prototype for -Wmissing-prototypes */
+G_BEGIN_DECLS
+extern
+void gimp_marshal_VOID__INT_INT_INT_INT (GClosure     *closure,
+                                         GValue       *return_value,
+                                         guint         n_param_values,
+                                         const GValue *param_values,
+                                         gpointer      invocation_hint,
+                                         gpointer      marshal_data);
+G_END_DECLS
+void
+gimp_marshal_VOID__INT_INT_INT_INT (GClosure     *closure,
+                                    GValue       *return_value G_GNUC_UNUSED,
+                                    guint         n_param_values,
+                                    const GValue *param_values,
+                                    gpointer      invocation_hint G_GNUC_UNUSED,
+                                    gpointer      marshal_data)
+{
+  typedef void (*GMarshalFunc_VOID__INT_INT_INT_INT) (gpointer data1,
+                                                      gint arg1,
+                                                      gint arg2,
+                                                      gint arg3,
+                                                      gint arg4,
+                                                      gpointer data2);
+  GCClosure *cc = (GCClosure *) closure;
+  gpointer data1, data2;
+  GMarshalFunc_VOID__INT_INT_INT_INT callback;
+
+  g_return_if_fail (n_param_values == 5);
+
+  if (G_CCLOSURE_SWAP_DATA (closure))
+    {
+      data1 = closure->data;
+      data2 = g_value_peek_pointer (param_values + 0);
+    }
+  else
+    {
+      data1 = g_value_peek_pointer (param_values + 0);
+      data2 = closure->data;
+    }
+  callback = (GMarshalFunc_VOID__INT_INT_INT_INT) (marshal_data ? marshal_data : cc->callback);
+
+  callback (data1,
+            g_marshal_value_peek_int (param_values + 1),
+            g_marshal_value_peek_int (param_values + 2),
+            g_marshal_value_peek_int (param_values + 3),
+            g_marshal_value_peek_int (param_values + 4),
+            data2);
+}
+
+/* VOID: INT, INT, BOOLEAN, BOOLEAN (../../../app/core/gimpmarshal.list:54) */
+/* Prototype for -Wmissing-prototypes */
+G_BEGIN_DECLS
+extern
+void gimp_marshal_VOID__INT_INT_BOOLEAN_BOOLEAN (GClosure     *closure,
+                                                 GValue       *return_value,
+                                                 guint         n_param_values,
+                                                 const GValue *param_values,
+                                                 gpointer      invocation_hint,
+                                                 gpointer      marshal_data);
+G_END_DECLS
+void
+gimp_marshal_VOID__INT_INT_BOOLEAN_BOOLEAN (GClosure     *closure,
+                                            GValue       *return_value G_GNUC_UNUSED,
+                                            guint         n_param_values,
+                                            const GValue *param_values,
+                                            gpointer      invocation_hint G_GNUC_UNUSED,
+                                            gpointer      marshal_data)
+{
+  typedef void (*GMarshalFunc_VOID__INT_INT_BOOLEAN_BOOLEAN) (gpointer data1,
+                                                              gint arg1,
+                                                              gint arg2,
+                                                              gboolean arg3,
+                                                              gboolean arg4,
+                                                              gpointer data2);
+  GCClosure *cc = (GCClosure *) closure;
+  gpointer data1, data2;
+  GMarshalFunc_VOID__INT_INT_BOOLEAN_BOOLEAN callback;
+
+  g_return_if_fail (n_param_values == 5);
+
+  if (G_CCLOSURE_SWAP_DATA (closure))
+    {
+      data1 = closure->data;
+      data2 = g_value_peek_pointer (param_values + 0);
+    }
+  else
+    {
+      data1 = g_value_peek_pointer (param_values + 0);
+      data2 = closure->data;
+    }
+  callback = (GMarshalFunc_VOID__INT_INT_BOOLEAN_BOOLEAN) (marshal_data ? marshal_data : cc->callback);
+
+  callback (data1,
+            g_marshal_value_peek_int (param_values + 1),
+            g_marshal_value_peek_int (param_values + 2),
+            g_marshal_value_peek_boolean (param_values + 3),
+            g_marshal_value_peek_boolean (param_values + 4),
+            data2);
+}
+
+/* VOID: INT, OBJECT (../../../app/core/gimpmarshal.list:55) */
+/* Prototype for -Wmissing-prototypes */
+G_BEGIN_DECLS
+extern
+void gimp_marshal_VOID__INT_OBJECT (GClosure     *closure,
+                                    GValue       *return_value,
+                                    guint         n_param_values,
+                                    const GValue *param_values,
+                                    gpointer      invocation_hint,
+                                    gpointer      marshal_data);
+G_END_DECLS
+void
+gimp_marshal_VOID__INT_OBJECT (GClosure     *closure,
+                               GValue       *return_value G_GNUC_UNUSED,
+                               guint         n_param_values,
+                               const GValue *param_values,
+                               gpointer      invocation_hint G_GNUC_UNUSED,
+                               gpointer      marshal_data)
+{
+  typedef void (*GMarshalFunc_VOID__INT_OBJECT) (gpointer data1,
+                                                 gint arg1,
+                                                 gpointer arg2,
+                                                 gpointer data2);
+  GCClosure *cc = (GCClosure *) closure;
+  gpointer data1, data2;
+  GMarshalFunc_VOID__INT_OBJECT callback;
+
+  g_return_if_fail (n_param_values == 3);
+
+  if (G_CCLOSURE_SWAP_DATA (closure))
+    {
+      data1 = closure->data;
+      data2 = g_value_peek_pointer (param_values + 0);
+    }
+  else
+    {
+      data1 = g_value_peek_pointer (param_values + 0);
+      data2 = closure->data;
+    }
+  callback = (GMarshalFunc_VOID__INT_OBJECT) (marshal_data ? marshal_data : cc->callback);
+
+  callback (data1,
+            g_marshal_value_peek_int (param_values + 1),
+            g_marshal_value_peek_object (param_values + 2),
+            data2);
+}
+
+/* VOID: OBJECT (../../../app/core/gimpmarshal.list:56) */
+#define gimp_marshal_VOID__OBJECT	g_cclosure_marshal_VOID__OBJECT
+
+/* VOID: OBJECT, BOOLEAN (../../../app/core/gimpmarshal.list:57) */
+/* Prototype for -Wmissing-prototypes */
+G_BEGIN_DECLS
+extern
+void gimp_marshal_VOID__OBJECT_BOOLEAN (GClosure     *closure,
+                                        GValue       *return_value,
+                                        guint         n_param_values,
+                                        const GValue *param_values,
+                                        gpointer      invocation_hint,
+                                        gpointer      marshal_data);
+G_END_DECLS
+void
+gimp_marshal_VOID__OBJECT_BOOLEAN (GClosure     *closure,
+                                   GValue       *return_value G_GNUC_UNUSED,
+                                   guint         n_param_values,
+                                   const GValue *param_values,
+                                   gpointer      invocation_hint G_GNUC_UNUSED,
+                                   gpointer      marshal_data)
+{
+  typedef void (*GMarshalFunc_VOID__OBJECT_BOOLEAN) (gpointer data1,
+                                                     gpointer arg1,
+                                                     gboolean arg2,
+                                                     gpointer data2);
+  GCClosure *cc = (GCClosure *) closure;
+  gpointer data1, data2;
+  GMarshalFunc_VOID__OBJECT_BOOLEAN callback;
+
+  g_return_if_fail (n_param_values == 3);
+
+  if (G_CCLOSURE_SWAP_DATA (closure))
+    {
+      data1 = closure->data;
+      data2 = g_value_peek_pointer (param_values + 0);
+    }
+  else
+    {
+      data1 = g_value_peek_pointer (param_values + 0);
+      data2 = closure->data;
+    }
+  callback = (GMarshalFunc_VOID__OBJECT_BOOLEAN) (marshal_data ? marshal_data : cc->callback);
+
+  callback (data1,
+            g_marshal_value_peek_object (param_values + 1),
+            g_marshal_value_peek_boolean (param_values + 2),
+            data2);
+}
+
+/* VOID: OBJECT, INT (../../../app/core/gimpmarshal.list:58) */
+/* Prototype for -Wmissing-prototypes */
+G_BEGIN_DECLS
+extern
+void gimp_marshal_VOID__OBJECT_INT (GClosure     *closure,
+                                    GValue       *return_value,
+                                    guint         n_param_values,
+                                    const GValue *param_values,
+                                    gpointer      invocation_hint,
+                                    gpointer      marshal_data);
+G_END_DECLS
+void
+gimp_marshal_VOID__OBJECT_INT (GClosure     *closure,
+                               GValue       *return_value G_GNUC_UNUSED,
+                               guint         n_param_values,
+                               const GValue *param_values,
+                               gpointer      invocation_hint G_GNUC_UNUSED,
+                               gpointer      marshal_data)
+{
+  typedef void (*GMarshalFunc_VOID__OBJECT_INT) (gpointer data1,
+                                                 gpointer arg1,
+                                                 gint arg2,
+                                                 gpointer data2);
+  GCClosure *cc = (GCClosure *) closure;
+  gpointer data1, data2;
+  GMarshalFunc_VOID__OBJECT_INT callback;
+
+  g_return_if_fail (n_param_values == 3);
+
+  if (G_CCLOSURE_SWAP_DATA (closure))
+    {
+      data1 = closure->data;
+      data2 = g_value_peek_pointer (param_values + 0);
+    }
+  else
+    {
+      data1 = g_value_peek_pointer (param_values + 0);
+      data2 = closure->data;
+    }
+  callback = (GMarshalFunc_VOID__OBJECT_INT) (marshal_data ? marshal_data : cc->callback);
+
+  callback (data1,
+            g_marshal_value_peek_object (param_values + 1),
+            g_marshal_value_peek_int (param_values + 2),
+            data2);
+}
+
+/* VOID: OBJECT, OBJECT (../../../app/core/gimpmarshal.list:59) */
+/* Prototype for -Wmissing-prototypes */
+G_BEGIN_DECLS
+extern
+void gimp_marshal_VOID__OBJECT_OBJECT (GClosure     *closure,
+                                       GValue       *return_value,
+                                       guint         n_param_values,
+                                       const GValue *param_values,
+                                       gpointer      invocation_hint,
+                                       gpointer      marshal_data);
+G_END_DECLS
+void
+gimp_marshal_VOID__OBJECT_OBJECT (GClosure     *closure,
+                                  GValue       *return_value G_GNUC_UNUSED,
+                                  guint         n_param_values,
+                                  const GValue *param_values,
+                                  gpointer      invocation_hint G_GNUC_UNUSED,
+                                  gpointer      marshal_data)
+{
+  typedef void (*GMarshalFunc_VOID__OBJECT_OBJECT) (gpointer data1,
+                                                    gpointer arg1,
+                                                    gpointer arg2,
+                                                    gpointer data2);
+  GCClosure *cc = (GCClosure *) closure;
+  gpointer data1, data2;
+  GMarshalFunc_VOID__OBJECT_OBJECT callback;
+
+  g_return_if_fail (n_param_values == 3);
+
+  if (G_CCLOSURE_SWAP_DATA (closure))
+    {
+      data1 = closure->data;
+      data2 = g_value_peek_pointer (param_values + 0);
+    }
+  else
+    {
+      data1 = g_value_peek_pointer (param_values + 0);
+      data2 = closure->data;
+    }
+  callback = (GMarshalFunc_VOID__OBJECT_OBJECT) (marshal_data ? marshal_data : cc->callback);
+
+  callback (data1,
+            g_marshal_value_peek_object (param_values + 1),
+            g_marshal_value_peek_object (param_values + 2),
+            data2);
+}
+
+/* VOID: OBJECT, POINTER (../../../app/core/gimpmarshal.list:60) */
+/* Prototype for -Wmissing-prototypes */
+G_BEGIN_DECLS
+extern
+void gimp_marshal_VOID__OBJECT_POINTER (GClosure     *closure,
+                                        GValue       *return_value,
+                                        guint         n_param_values,
+                                        const GValue *param_values,
+                                        gpointer      invocation_hint,
+                                        gpointer      marshal_data);
+G_END_DECLS
+void
+gimp_marshal_VOID__OBJECT_POINTER (GClosure     *closure,
+                                   GValue       *return_value G_GNUC_UNUSED,
+                                   guint         n_param_values,
+                                   const GValue *param_values,
+                                   gpointer      invocation_hint G_GNUC_UNUSED,
+                                   gpointer      marshal_data)
+{
+  typedef void (*GMarshalFunc_VOID__OBJECT_POINTER) (gpointer data1,
+                                                     gpointer arg1,
+                                                     gpointer arg2,
+                                                     gpointer data2);
+  GCClosure *cc = (GCClosure *) closure;
+  gpointer data1, data2;
+  GMarshalFunc_VOID__OBJECT_POINTER callback;
+
+  g_return_if_fail (n_param_values == 3);
+
+  if (G_CCLOSURE_SWAP_DATA (closure))
+    {
+      data1 = closure->data;
+      data2 = g_value_peek_pointer (param_values + 0);
+    }
+  else
+    {
+      data1 = g_value_peek_pointer (param_values + 0);
+      data2 = closure->data;
+    }
+  callback = (GMarshalFunc_VOID__OBJECT_POINTER) (marshal_data ? marshal_data : cc->callback);
+
+  callback (data1,
+            g_marshal_value_peek_object (param_values + 1),
+            g_marshal_value_peek_pointer (param_values + 2),
+            data2);
+}
+
+/* VOID: OBJECT, STRING, STRING (../../../app/core/gimpmarshal.list:61) */
+/* Prototype for -Wmissing-prototypes */
+G_BEGIN_DECLS
+extern
+void gimp_marshal_VOID__OBJECT_STRING_STRING (GClosure     *closure,
+                                              GValue       *return_value,
+                                              guint         n_param_values,
+                                              const GValue *param_values,
+                                              gpointer      invocation_hint,
+                                              gpointer      marshal_data);
+G_END_DECLS
+void
+gimp_marshal_VOID__OBJECT_STRING_STRING (GClosure     *closure,
+                                         GValue       *return_value G_GNUC_UNUSED,
+                                         guint         n_param_values,
+                                         const GValue *param_values,
+                                         gpointer      invocation_hint G_GNUC_UNUSED,
+                                         gpointer      marshal_data)
+{
+  typedef void (*GMarshalFunc_VOID__OBJECT_STRING_STRING) (gpointer data1,
+                                                           gpointer arg1,
+                                                           gpointer arg2,
+                                                           gpointer arg3,
+                                                           gpointer data2);
+  GCClosure *cc = (GCClosure *) closure;
+  gpointer data1, data2;
+  GMarshalFunc_VOID__OBJECT_STRING_STRING callback;
+
+  g_return_if_fail (n_param_values == 4);
+
+  if (G_CCLOSURE_SWAP_DATA (closure))
+    {
+      data1 = closure->data;
+      data2 = g_value_peek_pointer (param_values + 0);
+    }
+  else
+    {
+      data1 = g_value_peek_pointer (param_values + 0);
+      data2 = closure->data;
+    }
+  callback = (GMarshalFunc_VOID__OBJECT_STRING_STRING) (marshal_data ? marshal_data : cc->callback);
+
+  callback (data1,
+            g_marshal_value_peek_object (param_values + 1),
+            g_marshal_value_peek_string (param_values + 2),
+            g_marshal_value_peek_string (param_values + 3),
+            data2);
+}
+
+/* VOID: POINTER (../../../app/core/gimpmarshal.list:62) */
+#define gimp_marshal_VOID__POINTER	g_cclosure_marshal_VOID__POINTER
+
+/* VOID: POINTER, BOXED (../../../app/core/gimpmarshal.list:63) */
+/* Prototype for -Wmissing-prototypes */
+G_BEGIN_DECLS
+extern
+void gimp_marshal_VOID__POINTER_BOXED (GClosure     *closure,
+                                       GValue       *return_value,
+                                       guint         n_param_values,
+                                       const GValue *param_values,
+                                       gpointer      invocation_hint,
+                                       gpointer      marshal_data);
+G_END_DECLS
+void
+gimp_marshal_VOID__POINTER_BOXED (GClosure     *closure,
+                                  GValue       *return_value G_GNUC_UNUSED,
+                                  guint         n_param_values,
+                                  const GValue *param_values,
+                                  gpointer      invocation_hint G_GNUC_UNUSED,
+                                  gpointer      marshal_data)
+{
+  typedef void (*GMarshalFunc_VOID__POINTER_BOXED) (gpointer data1,
+                                                    gpointer arg1,
+                                                    gpointer arg2,
+                                                    gpointer data2);
+  GCClosure *cc = (GCClosure *) closure;
+  gpointer data1, data2;
+  GMarshalFunc_VOID__POINTER_BOXED callback;
+
+  g_return_if_fail (n_param_values == 3);
+
+  if (G_CCLOSURE_SWAP_DATA (closure))
+    {
+      data1 = closure->data;
+      data2 = g_value_peek_pointer (param_values + 0);
+    }
+  else
+    {
+      data1 = g_value_peek_pointer (param_values + 0);
+      data2 = closure->data;
+    }
+  callback = (GMarshalFunc_VOID__POINTER_BOXED) (marshal_data ? marshal_data : cc->callback);
+
+  callback (data1,
+            g_marshal_value_peek_pointer (param_values + 1),
+            g_marshal_value_peek_boxed (param_values + 2),
+            data2);
+}
+
+/* VOID: POINTER, ENUM (../../../app/core/gimpmarshal.list:64) */
+/* Prototype for -Wmissing-prototypes */
+G_BEGIN_DECLS
+extern
+void gimp_marshal_VOID__POINTER_ENUM (GClosure     *closure,
+                                      GValue       *return_value,
+                                      guint         n_param_values,
+                                      const GValue *param_values,
+                                      gpointer      invocation_hint,
+                                      gpointer      marshal_data);
+G_END_DECLS
+void
+gimp_marshal_VOID__POINTER_ENUM (GClosure     *closure,
+                                 GValue       *return_value G_GNUC_UNUSED,
+                                 guint         n_param_values,
+                                 const GValue *param_values,
+                                 gpointer      invocation_hint G_GNUC_UNUSED,
+                                 gpointer      marshal_data)
+{
+  typedef void (*GMarshalFunc_VOID__POINTER_ENUM) (gpointer data1,
+                                                   gpointer arg1,
+                                                   gint arg2,
+                                                   gpointer data2);
+  GCClosure *cc = (GCClosure *) closure;
+  gpointer data1, data2;
+  GMarshalFunc_VOID__POINTER_ENUM callback;
+
+  g_return_if_fail (n_param_values == 3);
+
+  if (G_CCLOSURE_SWAP_DATA (closure))
+    {
+      data1 = closure->data;
+      data2 = g_value_peek_pointer (param_values + 0);
+    }
+  else
+    {
+      data1 = g_value_peek_pointer (param_values + 0);
+      data2 = closure->data;
+    }
+  callback = (GMarshalFunc_VOID__POINTER_ENUM) (marshal_data ? marshal_data : cc->callback);
+
+  callback (data1,
+            g_marshal_value_peek_pointer (param_values + 1),
+            g_marshal_value_peek_enum (param_values + 2),
+            data2);
+}
+
+/* VOID: POINTER, FLAGS, BOOLEAN (../../../app/core/gimpmarshal.list:65) */
+/* Prototype for -Wmissing-prototypes */
+G_BEGIN_DECLS
+extern
+void gimp_marshal_VOID__POINTER_FLAGS_BOOLEAN (GClosure     *closure,
+                                               GValue       *return_value,
+                                               guint         n_param_values,
+                                               const GValue *param_values,
+                                               gpointer      invocation_hint,
+                                               gpointer      marshal_data);
+G_END_DECLS
+void
+gimp_marshal_VOID__POINTER_FLAGS_BOOLEAN (GClosure     *closure,
+                                          GValue       *return_value G_GNUC_UNUSED,
+                                          guint         n_param_values,
+                                          const GValue *param_values,
+                                          gpointer      invocation_hint G_GNUC_UNUSED,
+                                          gpointer      marshal_data)
+{
+  typedef void (*GMarshalFunc_VOID__POINTER_FLAGS_BOOLEAN) (gpointer data1,
+                                                            gpointer arg1,
+                                                            guint arg2,
+                                                            gboolean arg3,
+                                                            gpointer data2);
+  GCClosure *cc = (GCClosure *) closure;
+  gpointer data1, data2;
+  GMarshalFunc_VOID__POINTER_FLAGS_BOOLEAN callback;
+
+  g_return_if_fail (n_param_values == 4);
+
+  if (G_CCLOSURE_SWAP_DATA (closure))
+    {
+      data1 = closure->data;
+      data2 = g_value_peek_pointer (param_values + 0);
+    }
+  else
+    {
+      data1 = g_value_peek_pointer (param_values + 0);
+      data2 = closure->data;
+    }
+  callback = (GMarshalFunc_VOID__POINTER_FLAGS_BOOLEAN) (marshal_data ? marshal_data : cc->callback);
+
+  callback (data1,
+            g_marshal_value_peek_pointer (param_values + 1),
+            g_marshal_value_peek_flags (param_values + 2),
+            g_marshal_value_peek_boolean (param_values + 3),
+            data2);
+}
+
+/* VOID: POINTER, OBJECT, ENUM, POINTER, POINTER, BOXED (../../../app/core/gimpmarshal.list:66) */
+/* Prototype for -Wmissing-prototypes */
+G_BEGIN_DECLS
+extern
+void gimp_marshal_VOID__POINTER_OBJECT_ENUM_POINTER_POINTER_BOXED (GClosure     *closure,
+                                                                   GValue       *return_value,
+                                                                   guint         n_param_values,
+                                                                   const GValue *param_values,
+                                                                   gpointer      invocation_hint,
+                                                                   gpointer      marshal_data);
+G_END_DECLS
+void
+gimp_marshal_VOID__POINTER_OBJECT_ENUM_POINTER_POINTER_BOXED (GClosure     *closure,
+                                                              GValue       *return_value G_GNUC_UNUSED,
+                                                              guint         n_param_values,
+                                                              const GValue *param_values,
+                                                              gpointer      invocation_hint G_GNUC_UNUSED,
+                                                              gpointer      marshal_data)
+{
+  typedef void (*GMarshalFunc_VOID__POINTER_OBJECT_ENUM_POINTER_POINTER_BOXED) (gpointer data1,
+                                                                                gpointer arg1,
+                                                                                gpointer arg2,
+                                                                                gint arg3,
+                                                                                gpointer arg4,
+                                                                                gpointer arg5,
+                                                                                gpointer arg6,
+                                                                                gpointer data2);
+  GCClosure *cc = (GCClosure *) closure;
+  gpointer data1, data2;
+  GMarshalFunc_VOID__POINTER_OBJECT_ENUM_POINTER_POINTER_BOXED callback;
+
+  g_return_if_fail (n_param_values == 7);
+
+  if (G_CCLOSURE_SWAP_DATA (closure))
+    {
+      data1 = closure->data;
+      data2 = g_value_peek_pointer (param_values + 0);
+    }
+  else
+    {
+      data1 = g_value_peek_pointer (param_values + 0);
+      data2 = closure->data;
+    }
+  callback = (GMarshalFunc_VOID__POINTER_OBJECT_ENUM_POINTER_POINTER_BOXED) (marshal_data ? marshal_data : cc->callback);
+
+  callback (data1,
+            g_marshal_value_peek_pointer (param_values + 1),
+            g_marshal_value_peek_object (param_values + 2),
+            g_marshal_value_peek_enum (param_values + 3),
+            g_marshal_value_peek_pointer (param_values + 4),
+            g_marshal_value_peek_pointer (param_values + 5),
+            g_marshal_value_peek_boxed (param_values + 6),
+            data2);
+}
+
+/* VOID: POINTER, UINT, FLAGS (../../../app/core/gimpmarshal.list:67) */
+/* Prototype for -Wmissing-prototypes */
+G_BEGIN_DECLS
+extern
+void gimp_marshal_VOID__POINTER_UINT_FLAGS (GClosure     *closure,
+                                            GValue       *return_value,
+                                            guint         n_param_values,
+                                            const GValue *param_values,
+                                            gpointer      invocation_hint,
+                                            gpointer      marshal_data);
+G_END_DECLS
+void
+gimp_marshal_VOID__POINTER_UINT_FLAGS (GClosure     *closure,
+                                       GValue       *return_value G_GNUC_UNUSED,
+                                       guint         n_param_values,
+                                       const GValue *param_values,
+                                       gpointer      invocation_hint G_GNUC_UNUSED,
+                                       gpointer      marshal_data)
+{
+  typedef void (*GMarshalFunc_VOID__POINTER_UINT_FLAGS) (gpointer data1,
+                                                         gpointer arg1,
+                                                         guint arg2,
+                                                         guint arg3,
+                                                         gpointer data2);
+  GCClosure *cc = (GCClosure *) closure;
+  gpointer data1, data2;
+  GMarshalFunc_VOID__POINTER_UINT_FLAGS callback;
+
+  g_return_if_fail (n_param_values == 4);
+
+  if (G_CCLOSURE_SWAP_DATA (closure))
+    {
+      data1 = closure->data;
+      data2 = g_value_peek_pointer (param_values + 0);
+    }
+  else
+    {
+      data1 = g_value_peek_pointer (param_values + 0);
+      data2 = closure->data;
+    }
+  callback = (GMarshalFunc_VOID__POINTER_UINT_FLAGS) (marshal_data ? marshal_data : cc->callback);
+
+  callback (data1,
+            g_marshal_value_peek_pointer (param_values + 1),
+            g_marshal_value_peek_uint (param_values + 2),
+            g_marshal_value_peek_flags (param_values + 3),
+            data2);
+}
+
+/* VOID: STRING (../../../app/core/gimpmarshal.list:68) */
+#define gimp_marshal_VOID__STRING	g_cclosure_marshal_VOID__STRING
+
+/* VOID: STRING, BOOLEAN, UINT, FLAGS (../../../app/core/gimpmarshal.list:69) */
+/* Prototype for -Wmissing-prototypes */
+G_BEGIN_DECLS
+extern
+void gimp_marshal_VOID__STRING_BOOLEAN_UINT_FLAGS (GClosure     *closure,
+                                                   GValue       *return_value,
+                                                   guint         n_param_values,
+                                                   const GValue *param_values,
+                                                   gpointer      invocation_hint,
+                                                   gpointer      marshal_data);
+G_END_DECLS
+void
+gimp_marshal_VOID__STRING_BOOLEAN_UINT_FLAGS (GClosure     *closure,
+                                              GValue       *return_value G_GNUC_UNUSED,
+                                              guint         n_param_values,
+                                              const GValue *param_values,
+                                              gpointer      invocation_hint G_GNUC_UNUSED,
+                                              gpointer      marshal_data)
+{
+  typedef void (*GMarshalFunc_VOID__STRING_BOOLEAN_UINT_FLAGS) (gpointer data1,
+                                                                gpointer arg1,
+                                                                gboolean arg2,
+                                                                guint arg3,
+                                                                guint arg4,
+                                                                gpointer data2);
+  GCClosure *cc = (GCClosure *) closure;
+  gpointer data1, data2;
+  GMarshalFunc_VOID__STRING_BOOLEAN_UINT_FLAGS callback;
+
+  g_return_if_fail (n_param_values == 5);
+
+  if (G_CCLOSURE_SWAP_DATA (closure))
+    {
+      data1 = closure->data;
+      data2 = g_value_peek_pointer (param_values + 0);
+    }
+  else
+    {
+      data1 = g_value_peek_pointer (param_values + 0);
+      data2 = closure->data;
+    }
+  callback = (GMarshalFunc_VOID__STRING_BOOLEAN_UINT_FLAGS) (marshal_data ? marshal_data : cc->callback);
+
+  callback (data1,
+            g_marshal_value_peek_string (param_values + 1),
+            g_marshal_value_peek_boolean (param_values + 2),
+            g_marshal_value_peek_uint (param_values + 3),
+            g_marshal_value_peek_flags (param_values + 4),
+            data2);
+}
+
+/* VOID: STRING, DOUBLE, STRING, DOUBLE, STRING (../../../app/core/gimpmarshal.list:70) */
+/* Prototype for -Wmissing-prototypes */
+G_BEGIN_DECLS
+extern
+void gimp_marshal_VOID__STRING_DOUBLE_STRING_DOUBLE_STRING (GClosure     *closure,
+                                                            GValue       *return_value,
+                                                            guint         n_param_values,
+                                                            const GValue *param_values,
+                                                            gpointer      invocation_hint,
+                                                            gpointer      marshal_data);
+G_END_DECLS
+void
+gimp_marshal_VOID__STRING_DOUBLE_STRING_DOUBLE_STRING (GClosure     *closure,
+                                                       GValue       *return_value G_GNUC_UNUSED,
+                                                       guint         n_param_values,
+                                                       const GValue *param_values,
+                                                       gpointer      invocation_hint G_GNUC_UNUSED,
+                                                       gpointer      marshal_data)
+{
+  typedef void (*GMarshalFunc_VOID__STRING_DOUBLE_STRING_DOUBLE_STRING) (gpointer data1,
+                                                                         gpointer arg1,
+                                                                         gdouble arg2,
+                                                                         gpointer arg3,
+                                                                         gdouble arg4,
+                                                                         gpointer arg5,
+                                                                         gpointer data2);
+  GCClosure *cc = (GCClosure *) closure;
+  gpointer data1, data2;
+  GMarshalFunc_VOID__STRING_DOUBLE_STRING_DOUBLE_STRING callback;
+
+  g_return_if_fail (n_param_values == 6);
+
+  if (G_CCLOSURE_SWAP_DATA (closure))
+    {
+      data1 = closure->data;
+      data2 = g_value_peek_pointer (param_values + 0);
+    }
+  else
+    {
+      data1 = g_value_peek_pointer (param_values + 0);
+      data2 = closure->data;
+    }
+  callback = (GMarshalFunc_VOID__STRING_DOUBLE_STRING_DOUBLE_STRING) (marshal_data ? marshal_data : cc->callback);
+
+  callback (data1,
+            g_marshal_value_peek_string (param_values + 1),
+            g_marshal_value_peek_double (param_values + 2),
+            g_marshal_value_peek_string (param_values + 3),
+            g_marshal_value_peek_double (param_values + 4),
+            g_marshal_value_peek_string (param_values + 5),
+            data2);
+}
+
+/* VOID: STRING, FLAGS (../../../app/core/gimpmarshal.list:71) */
+/* Prototype for -Wmissing-prototypes */
+G_BEGIN_DECLS
+extern
+void gimp_marshal_VOID__STRING_FLAGS (GClosure     *closure,
+                                      GValue       *return_value,
+                                      guint         n_param_values,
+                                      const GValue *param_values,
+                                      gpointer      invocation_hint,
+                                      gpointer      marshal_data);
+G_END_DECLS
+void
+gimp_marshal_VOID__STRING_FLAGS (GClosure     *closure,
+                                 GValue       *return_value G_GNUC_UNUSED,
+                                 guint         n_param_values,
+                                 const GValue *param_values,
+                                 gpointer      invocation_hint G_GNUC_UNUSED,
+                                 gpointer      marshal_data)
+{
+  typedef void (*GMarshalFunc_VOID__STRING_FLAGS) (gpointer data1,
+                                                   gpointer arg1,
+                                                   guint arg2,
+                                                   gpointer data2);
+  GCClosure *cc = (GCClosure *) closure;
+  gpointer data1, data2;
+  GMarshalFunc_VOID__STRING_FLAGS callback;
+
+  g_return_if_fail (n_param_values == 3);
+
+  if (G_CCLOSURE_SWAP_DATA (closure))
+    {
+      data1 = closure->data;
+      data2 = g_value_peek_pointer (param_values + 0);
+    }
+  else
+    {
+      data1 = g_value_peek_pointer (param_values + 0);
+      data2 = closure->data;
+    }
+  callback = (GMarshalFunc_VOID__STRING_FLAGS) (marshal_data ? marshal_data : cc->callback);
+
+  callback (data1,
+            g_marshal_value_peek_string (param_values + 1),
+            g_marshal_value_peek_flags (param_values + 2),
+            data2);
+}
+
+/* VOID: STRING, STRING, STRING (../../../app/core/gimpmarshal.list:72) */
+/* Prototype for -Wmissing-prototypes */
+G_BEGIN_DECLS
+extern
+void gimp_marshal_VOID__STRING_STRING_STRING (GClosure     *closure,
+                                              GValue       *return_value,
+                                              guint         n_param_values,
+                                              const GValue *param_values,
+                                              gpointer      invocation_hint,
+                                              gpointer      marshal_data);
+G_END_DECLS
+void
+gimp_marshal_VOID__STRING_STRING_STRING (GClosure     *closure,
+                                         GValue       *return_value G_GNUC_UNUSED,
+                                         guint         n_param_values,
+                                         const GValue *param_values,
+                                         gpointer      invocation_hint G_GNUC_UNUSED,
+                                         gpointer      marshal_data)
+{
+  typedef void (*GMarshalFunc_VOID__STRING_STRING_STRING) (gpointer data1,
+                                                           gpointer arg1,
+                                                           gpointer arg2,
+                                                           gpointer arg3,
+                                                           gpointer data2);
+  GCClosure *cc = (GCClosure *) closure;
+  gpointer data1, data2;
+  GMarshalFunc_VOID__STRING_STRING_STRING callback;
+
+  g_return_if_fail (n_param_values == 4);
+
+  if (G_CCLOSURE_SWAP_DATA (closure))
+    {
+      data1 = closure->data;
+      data2 = g_value_peek_pointer (param_values + 0);
+    }
+  else
+    {
+      data1 = g_value_peek_pointer (param_values + 0);
+      data2 = closure->data;
+    }
+  callback = (GMarshalFunc_VOID__STRING_STRING_STRING) (marshal_data ? marshal_data : cc->callback);
+
+  callback (data1,
+            g_marshal_value_peek_string (param_values + 1),
+            g_marshal_value_peek_string (param_values + 2),
+            g_marshal_value_peek_string (param_values + 3),
+            data2);
+}
+
+/* VOID: VARIANT (../../../app/core/gimpmarshal.list:73) */
+#define gimp_marshal_VOID__VARIANT	g_cclosure_marshal_VOID__VARIANT
+
+/* VOID: VOID (../../../app/core/gimpmarshal.list:74) */
+#define gimp_marshal_VOID__VOID	g_cclosure_marshal_VOID__VOID
+
diff --git a/app/core/gimpmarshal.h b/app/core/gimpmarshal.h
new file mode 100644
index 0000000..e8247a2
--- /dev/null
+++ b/app/core/gimpmarshal.h
@@ -0,0 +1,378 @@
+/* This file is generated by glib-genmarshal, do not modify it. This code is licensed under the same license as the containing project. Note that it links to GLib, so must comply with the LGPL linking clauses. */
+#ifndef __GIMP_MARSHAL_MARSHAL_H__
+#define __GIMP_MARSHAL_MARSHAL_H__
+
+#include <glib-object.h>
+
+G_BEGIN_DECLS
+
+/* BOOLEAN: BOOLEAN (../../../app/core/gimpmarshal.list:25) */
+extern
+void gimp_marshal_BOOLEAN__BOOLEAN (GClosure     *closure,
+                                    GValue       *return_value,
+                                    guint         n_param_values,
+                                    const GValue *param_values,
+                                    gpointer      invocation_hint,
+                                    gpointer      marshal_data);
+
+/* BOOLEAN: DOUBLE (../../../app/core/gimpmarshal.list:26) */
+extern
+void gimp_marshal_BOOLEAN__DOUBLE (GClosure     *closure,
+                                   GValue       *return_value,
+                                   guint         n_param_values,
+                                   const GValue *param_values,
+                                   gpointer      invocation_hint,
+                                   gpointer      marshal_data);
+
+/* BOOLEAN: ENUM, INT (../../../app/core/gimpmarshal.list:27) */
+extern
+void gimp_marshal_BOOLEAN__ENUM_INT (GClosure     *closure,
+                                     GValue       *return_value,
+                                     guint         n_param_values,
+                                     const GValue *param_values,
+                                     gpointer      invocation_hint,
+                                     gpointer      marshal_data);
+
+/* BOOLEAN: INT, UINT, ENUM (../../../app/core/gimpmarshal.list:28) */
+extern
+void gimp_marshal_BOOLEAN__INT_UINT_ENUM (GClosure     *closure,
+                                          GValue       *return_value,
+                                          guint         n_param_values,
+                                          const GValue *param_values,
+                                          gpointer      invocation_hint,
+                                          gpointer      marshal_data);
+
+/* BOOLEAN: OBJECT (../../../app/core/gimpmarshal.list:29) */
+extern
+void gimp_marshal_BOOLEAN__OBJECT (GClosure     *closure,
+                                   GValue       *return_value,
+                                   guint         n_param_values,
+                                   const GValue *param_values,
+                                   gpointer      invocation_hint,
+                                   gpointer      marshal_data);
+
+/* BOOLEAN: OBJECT, POINTER (../../../app/core/gimpmarshal.list:30) */
+extern
+void gimp_marshal_BOOLEAN__OBJECT_POINTER (GClosure     *closure,
+                                           GValue       *return_value,
+                                           guint         n_param_values,
+                                           const GValue *param_values,
+                                           gpointer      invocation_hint,
+                                           gpointer      marshal_data);
+
+/* BOOLEAN: OBJECT, POINTER, STRING (../../../app/core/gimpmarshal.list:31) */
+extern
+void gimp_marshal_BOOLEAN__OBJECT_POINTER_STRING (GClosure     *closure,
+                                                  GValue       *return_value,
+                                                  guint         n_param_values,
+                                                  const GValue *param_values,
+                                                  gpointer      invocation_hint,
+                                                  gpointer      marshal_data);
+
+/* BOOLEAN: STRING (../../../app/core/gimpmarshal.list:32) */
+extern
+void gimp_marshal_BOOLEAN__STRING (GClosure     *closure,
+                                   GValue       *return_value,
+                                   guint         n_param_values,
+                                   const GValue *param_values,
+                                   gpointer      invocation_hint,
+                                   gpointer      marshal_data);
+
+/* BOOLEAN: STRING, FLAGS (../../../app/core/gimpmarshal.list:33) */
+extern
+void gimp_marshal_BOOLEAN__STRING_FLAGS (GClosure     *closure,
+                                         GValue       *return_value,
+                                         guint         n_param_values,
+                                         const GValue *param_values,
+                                         gpointer      invocation_hint,
+                                         gpointer      marshal_data);
+
+/* INT: DOUBLE (../../../app/core/gimpmarshal.list:35) */
+extern
+void gimp_marshal_INT__DOUBLE (GClosure     *closure,
+                               GValue       *return_value,
+                               guint         n_param_values,
+                               const GValue *param_values,
+                               gpointer      invocation_hint,
+                               gpointer      marshal_data);
+
+/* VOID: BOOLEAN (../../../app/core/gimpmarshal.list:37) */
+#define gimp_marshal_VOID__BOOLEAN	g_cclosure_marshal_VOID__BOOLEAN
+
+/* VOID: BOOLEAN, INT, INT, INT, INT (../../../app/core/gimpmarshal.list:38) */
+extern
+void gimp_marshal_VOID__BOOLEAN_INT_INT_INT_INT (GClosure     *closure,
+                                                 GValue       *return_value,
+                                                 guint         n_param_values,
+                                                 const GValue *param_values,
+                                                 gpointer      invocation_hint,
+                                                 gpointer      marshal_data);
+
+/* VOID: BOXED (../../../app/core/gimpmarshal.list:39) */
+#define gimp_marshal_VOID__BOXED	g_cclosure_marshal_VOID__BOXED
+
+/* VOID: BOXED, ENUM (../../../app/core/gimpmarshal.list:40) */
+extern
+void gimp_marshal_VOID__BOXED_ENUM (GClosure     *closure,
+                                    GValue       *return_value,
+                                    guint         n_param_values,
+                                    const GValue *param_values,
+                                    gpointer      invocation_hint,
+                                    gpointer      marshal_data);
+
+/* VOID: DOUBLE (../../../app/core/gimpmarshal.list:41) */
+#define gimp_marshal_VOID__DOUBLE	g_cclosure_marshal_VOID__DOUBLE
+
+/* VOID: DOUBLE, DOUBLE (../../../app/core/gimpmarshal.list:42) */
+extern
+void gimp_marshal_VOID__DOUBLE_DOUBLE (GClosure     *closure,
+                                       GValue       *return_value,
+                                       guint         n_param_values,
+                                       const GValue *param_values,
+                                       gpointer      invocation_hint,
+                                       gpointer      marshal_data);
+
+/* VOID: DOUBLE, DOUBLE, DOUBLE, DOUBLE (../../../app/core/gimpmarshal.list:43) */
+extern
+void gimp_marshal_VOID__DOUBLE_DOUBLE_DOUBLE_DOUBLE (GClosure     *closure,
+                                                     GValue       *return_value,
+                                                     guint         n_param_values,
+                                                     const GValue *param_values,
+                                                     gpointer      invocation_hint,
+                                                     gpointer      marshal_data);
+
+/* VOID: ENUM (../../../app/core/gimpmarshal.list:44) */
+#define gimp_marshal_VOID__ENUM	g_cclosure_marshal_VOID__ENUM
+
+/* VOID: ENUM, INT (../../../app/core/gimpmarshal.list:45) */
+extern
+void gimp_marshal_VOID__ENUM_INT (GClosure     *closure,
+                                  GValue       *return_value,
+                                  guint         n_param_values,
+                                  const GValue *param_values,
+                                  gpointer      invocation_hint,
+                                  gpointer      marshal_data);
+
+/* VOID: ENUM, INT, BOOLEAN (../../../app/core/gimpmarshal.list:46) */
+extern
+void gimp_marshal_VOID__ENUM_INT_BOOLEAN (GClosure     *closure,
+                                          GValue       *return_value,
+                                          guint         n_param_values,
+                                          const GValue *param_values,
+                                          gpointer      invocation_hint,
+                                          gpointer      marshal_data);
+
+/* VOID: ENUM, OBJECT (../../../app/core/gimpmarshal.list:47) */
+extern
+void gimp_marshal_VOID__ENUM_OBJECT (GClosure     *closure,
+                                     GValue       *return_value,
+                                     guint         n_param_values,
+                                     const GValue *param_values,
+                                     gpointer      invocation_hint,
+                                     gpointer      marshal_data);
+
+/* VOID: ENUM, POINTER (../../../app/core/gimpmarshal.list:48) */
+extern
+void gimp_marshal_VOID__ENUM_POINTER (GClosure     *closure,
+                                      GValue       *return_value,
+                                      guint         n_param_values,
+                                      const GValue *param_values,
+                                      gpointer      invocation_hint,
+                                      gpointer      marshal_data);
+
+/* VOID: FLAGS (../../../app/core/gimpmarshal.list:49) */
+#define gimp_marshal_VOID__FLAGS	g_cclosure_marshal_VOID__FLAGS
+
+/* VOID: INT (../../../app/core/gimpmarshal.list:50) */
+#define gimp_marshal_VOID__INT	g_cclosure_marshal_VOID__INT
+
+/* VOID: INT, BOOLEAN (../../../app/core/gimpmarshal.list:51) */
+extern
+void gimp_marshal_VOID__INT_BOOLEAN (GClosure     *closure,
+                                     GValue       *return_value,
+                                     guint         n_param_values,
+                                     const GValue *param_values,
+                                     gpointer      invocation_hint,
+                                     gpointer      marshal_data);
+
+/* VOID: INT, INT (../../../app/core/gimpmarshal.list:52) */
+extern
+void gimp_marshal_VOID__INT_INT (GClosure     *closure,
+                                 GValue       *return_value,
+                                 guint         n_param_values,
+                                 const GValue *param_values,
+                                 gpointer      invocation_hint,
+                                 gpointer      marshal_data);
+
+/* VOID: INT, INT, INT, INT (../../../app/core/gimpmarshal.list:53) */
+extern
+void gimp_marshal_VOID__INT_INT_INT_INT (GClosure     *closure,
+                                         GValue       *return_value,
+                                         guint         n_param_values,
+                                         const GValue *param_values,
+                                         gpointer      invocation_hint,
+                                         gpointer      marshal_data);
+
+/* VOID: INT, INT, BOOLEAN, BOOLEAN (../../../app/core/gimpmarshal.list:54) */
+extern
+void gimp_marshal_VOID__INT_INT_BOOLEAN_BOOLEAN (GClosure     *closure,
+                                                 GValue       *return_value,
+                                                 guint         n_param_values,
+                                                 const GValue *param_values,
+                                                 gpointer      invocation_hint,
+                                                 gpointer      marshal_data);
+
+/* VOID: INT, OBJECT (../../../app/core/gimpmarshal.list:55) */
+extern
+void gimp_marshal_VOID__INT_OBJECT (GClosure     *closure,
+                                    GValue       *return_value,
+                                    guint         n_param_values,
+                                    const GValue *param_values,
+                                    gpointer      invocation_hint,
+                                    gpointer      marshal_data);
+
+/* VOID: OBJECT (../../../app/core/gimpmarshal.list:56) */
+#define gimp_marshal_VOID__OBJECT	g_cclosure_marshal_VOID__OBJECT
+
+/* VOID: OBJECT, BOOLEAN (../../../app/core/gimpmarshal.list:57) */
+extern
+void gimp_marshal_VOID__OBJECT_BOOLEAN (GClosure     *closure,
+                                        GValue       *return_value,
+                                        guint         n_param_values,
+                                        const GValue *param_values,
+                                        gpointer      invocation_hint,
+                                        gpointer      marshal_data);
+
+/* VOID: OBJECT, INT (../../../app/core/gimpmarshal.list:58) */
+extern
+void gimp_marshal_VOID__OBJECT_INT (GClosure     *closure,
+                                    GValue       *return_value,
+                                    guint         n_param_values,
+                                    const GValue *param_values,
+                                    gpointer      invocation_hint,
+                                    gpointer      marshal_data);
+
+/* VOID: OBJECT, OBJECT (../../../app/core/gimpmarshal.list:59) */
+extern
+void gimp_marshal_VOID__OBJECT_OBJECT (GClosure     *closure,
+                                       GValue       *return_value,
+                                       guint         n_param_values,
+                                       const GValue *param_values,
+                                       gpointer      invocation_hint,
+                                       gpointer      marshal_data);
+
+/* VOID: OBJECT, POINTER (../../../app/core/gimpmarshal.list:60) */
+extern
+void gimp_marshal_VOID__OBJECT_POINTER (GClosure     *closure,
+                                        GValue       *return_value,
+                                        guint         n_param_values,
+                                        const GValue *param_values,
+                                        gpointer      invocation_hint,
+                                        gpointer      marshal_data);
+
+/* VOID: OBJECT, STRING, STRING (../../../app/core/gimpmarshal.list:61) */
+extern
+void gimp_marshal_VOID__OBJECT_STRING_STRING (GClosure     *closure,
+                                              GValue       *return_value,
+                                              guint         n_param_values,
+                                              const GValue *param_values,
+                                              gpointer      invocation_hint,
+                                              gpointer      marshal_data);
+
+/* VOID: POINTER (../../../app/core/gimpmarshal.list:62) */
+#define gimp_marshal_VOID__POINTER	g_cclosure_marshal_VOID__POINTER
+
+/* VOID: POINTER, BOXED (../../../app/core/gimpmarshal.list:63) */
+extern
+void gimp_marshal_VOID__POINTER_BOXED (GClosure     *closure,
+                                       GValue       *return_value,
+                                       guint         n_param_values,
+                                       const GValue *param_values,
+                                       gpointer      invocation_hint,
+                                       gpointer      marshal_data);
+
+/* VOID: POINTER, ENUM (../../../app/core/gimpmarshal.list:64) */
+extern
+void gimp_marshal_VOID__POINTER_ENUM (GClosure     *closure,
+                                      GValue       *return_value,
+                                      guint         n_param_values,
+                                      const GValue *param_values,
+                                      gpointer      invocation_hint,
+                                      gpointer      marshal_data);
+
+/* VOID: POINTER, FLAGS, BOOLEAN (../../../app/core/gimpmarshal.list:65) */
+extern
+void gimp_marshal_VOID__POINTER_FLAGS_BOOLEAN (GClosure     *closure,
+                                               GValue       *return_value,
+                                               guint         n_param_values,
+                                               const GValue *param_values,
+                                               gpointer      invocation_hint,
+                                               gpointer      marshal_data);
+
+/* VOID: POINTER, OBJECT, ENUM, POINTER, POINTER, BOXED (../../../app/core/gimpmarshal.list:66) */
+extern
+void gimp_marshal_VOID__POINTER_OBJECT_ENUM_POINTER_POINTER_BOXED (GClosure     *closure,
+                                                                   GValue       *return_value,
+                                                                   guint         n_param_values,
+                                                                   const GValue *param_values,
+                                                                   gpointer      invocation_hint,
+                                                                   gpointer      marshal_data);
+
+/* VOID: POINTER, UINT, FLAGS (../../../app/core/gimpmarshal.list:67) */
+extern
+void gimp_marshal_VOID__POINTER_UINT_FLAGS (GClosure     *closure,
+                                            GValue       *return_value,
+                                            guint         n_param_values,
+                                            const GValue *param_values,
+                                            gpointer      invocation_hint,
+                                            gpointer      marshal_data);
+
+/* VOID: STRING (../../../app/core/gimpmarshal.list:68) */
+#define gimp_marshal_VOID__STRING	g_cclosure_marshal_VOID__STRING
+
+/* VOID: STRING, BOOLEAN, UINT, FLAGS (../../../app/core/gimpmarshal.list:69) */
+extern
+void gimp_marshal_VOID__STRING_BOOLEAN_UINT_FLAGS (GClosure     *closure,
+                                                   GValue       *return_value,
+                                                   guint         n_param_values,
+                                                   const GValue *param_values,
+                                                   gpointer      invocation_hint,
+                                                   gpointer      marshal_data);
+
+/* VOID: STRING, DOUBLE, STRING, DOUBLE, STRING (../../../app/core/gimpmarshal.list:70) */
+extern
+void gimp_marshal_VOID__STRING_DOUBLE_STRING_DOUBLE_STRING (GClosure     *closure,
+                                                            GValue       *return_value,
+                                                            guint         n_param_values,
+                                                            const GValue *param_values,
+                                                            gpointer      invocation_hint,
+                                                            gpointer      marshal_data);
+
+/* VOID: STRING, FLAGS (../../../app/core/gimpmarshal.list:71) */
+extern
+void gimp_marshal_VOID__STRING_FLAGS (GClosure     *closure,
+                                      GValue       *return_value,
+                                      guint         n_param_values,
+                                      const GValue *param_values,
+                                      gpointer      invocation_hint,
+                                      gpointer      marshal_data);
+
+/* VOID: STRING, STRING, STRING (../../../app/core/gimpmarshal.list:72) */
+extern
+void gimp_marshal_VOID__STRING_STRING_STRING (GClosure     *closure,
+                                              GValue       *return_value,
+                                              guint         n_param_values,
+                                              const GValue *param_values,
+                                              gpointer      invocation_hint,
+                                              gpointer      marshal_data);
+
+/* VOID: VARIANT (../../../app/core/gimpmarshal.list:73) */
+#define gimp_marshal_VOID__VARIANT	g_cclosure_marshal_VOID__VARIANT
+
+/* VOID: VOID (../../../app/core/gimpmarshal.list:74) */
+#define gimp_marshal_VOID__VOID	g_cclosure_marshal_VOID__VOID
+
+
+G_END_DECLS
+
+#endif /* __GIMP_MARSHAL_MARSHAL_H__ */
diff --git a/app/core/gimpmarshal.list b/app/core/gimpmarshal.list
new file mode 100644
index 0000000..f09116e
--- /dev/null
+++ b/app/core/gimpmarshal.list
@@ -0,0 +1,74 @@
+# see glib-genmarshal(1) for a detailed description of the file format,
+# possible parameter types are:
+#   VOID        indicates   no   return   type,  or  no  extra
+#               parameters. if VOID is used as  the  parameter
+#               list, no additional parameters may be present.
+#   BOOLEAN     for boolean types (gboolean)
+#   CHAR        for signed char types (gchar)
+#   UCHAR       for unsigned char types (guchar)
+#   INT         for signed integer types (gint)
+#   UINT        for unsigned integer types (guint)
+#   LONG        for signed long integer types (glong)
+#   ULONG       for unsigned long integer types (gulong)
+#   ENUM        for enumeration types (gint)
+#   FLAGS       for flag enumeration types (guint)
+#   FLOAT       for single-precision float types (gfloat)
+#   DOUBLE      for double-precision float types (gdouble)
+#   STRING      for string types (gchar*)
+#   BOXED       for boxed (anonymous but reference counted) types (GBoxed*)
+#   POINTER     for anonymous pointer types (gpointer)
+#   PARAM       for GParamSpec or derived types  (GParamSpec*)
+#   OBJECT      for GObject or derived types (GObject*)
+#   NONE        deprecated alias for VOID
+#   BOOL        deprecated alias for BOOLEAN
+
+BOOLEAN: BOOLEAN
+BOOLEAN: DOUBLE
+BOOLEAN: ENUM, INT
+BOOLEAN: INT, UINT, ENUM
+BOOLEAN: OBJECT
+BOOLEAN: OBJECT, POINTER
+BOOLEAN: OBJECT, POINTER, STRING
+BOOLEAN: STRING
+BOOLEAN: STRING, FLAGS
+
+INT: DOUBLE
+
+VOID: BOOLEAN
+VOID: BOOLEAN, INT, INT, INT, INT
+VOID: BOXED
+VOID: BOXED, ENUM
+VOID: DOUBLE
+VOID: DOUBLE, DOUBLE
+VOID: DOUBLE, DOUBLE, DOUBLE, DOUBLE
+VOID: ENUM
+VOID: ENUM, INT
+VOID: ENUM, INT, BOOLEAN
+VOID: ENUM, OBJECT
+VOID: ENUM, POINTER
+VOID: FLAGS
+VOID: INT
+VOID: INT, BOOLEAN
+VOID: INT, INT
+VOID: INT, INT, INT, INT
+VOID: INT, INT, BOOLEAN, BOOLEAN
+VOID: INT, OBJECT
+VOID: OBJECT
+VOID: OBJECT, BOOLEAN
+VOID: OBJECT, INT
+VOID: OBJECT, OBJECT
+VOID: OBJECT, POINTER
+VOID: OBJECT, STRING, STRING
+VOID: POINTER
+VOID: POINTER, BOXED
+VOID: POINTER, ENUM
+VOID: POINTER, FLAGS, BOOLEAN
+VOID: POINTER, OBJECT, ENUM, POINTER, POINTER, BOXED
+VOID: POINTER, UINT, FLAGS
+VOID: STRING
+VOID: STRING, BOOLEAN, UINT, FLAGS
+VOID: STRING, DOUBLE, STRING, DOUBLE, STRING
+VOID: STRING, FLAGS
+VOID: STRING, STRING, STRING
+VOID: VARIANT
+VOID: VOID
diff --git a/app/core/gimpmaskundo.c b/app/core/gimpmaskundo.c
new file mode 100644
index 0000000..d388ee5
--- /dev/null
+++ b/app/core/gimpmaskundo.c
@@ -0,0 +1,292 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gegl/gimp-gegl-loops.h"
+
+#include "gimp-memsize.h"
+#include "gimpchannel.h"
+#include "gimpmaskundo.h"
+
+
+enum
+{
+  PROP_0,
+  PROP_CONVERT_FORMAT
+};
+
+
+static void     gimp_mask_undo_constructed  (GObject             *object);
+static void     gimp_mask_undo_set_property (GObject             *object,
+                                             guint                property_id,
+                                             const GValue        *value,
+                                             GParamSpec          *pspec);
+static void     gimp_mask_undo_get_property (GObject             *object,
+                                             guint                property_id,
+                                             GValue              *value,
+                                             GParamSpec          *pspec);
+
+static gint64   gimp_mask_undo_get_memsize  (GimpObject          *object,
+                                             gint64              *gui_size);
+
+static void     gimp_mask_undo_pop          (GimpUndo            *undo,
+                                             GimpUndoMode         undo_mode,
+                                             GimpUndoAccumulator *accum);
+static void     gimp_mask_undo_free         (GimpUndo            *undo,
+                                             GimpUndoMode         undo_mode);
+
+
+G_DEFINE_TYPE (GimpMaskUndo, gimp_mask_undo, GIMP_TYPE_ITEM_UNDO)
+
+#define parent_class gimp_mask_undo_parent_class
+
+
+static void
+gimp_mask_undo_class_init (GimpMaskUndoClass *klass)
+{
+  GObjectClass    *object_class      = G_OBJECT_CLASS (klass);
+  GimpObjectClass *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+  GimpUndoClass   *undo_class        = GIMP_UNDO_CLASS (klass);
+
+  object_class->constructed      = gimp_mask_undo_constructed;
+  object_class->set_property     = gimp_mask_undo_set_property;
+  object_class->get_property     = gimp_mask_undo_get_property;
+
+  gimp_object_class->get_memsize = gimp_mask_undo_get_memsize;
+
+  undo_class->pop                = gimp_mask_undo_pop;
+  undo_class->free               = gimp_mask_undo_free;
+
+  g_object_class_install_property (object_class, PROP_CONVERT_FORMAT,
+                                   g_param_spec_boolean ("convert-format",
+                                                         NULL, NULL,
+                                                         FALSE,
+                                                         GIMP_PARAM_READWRITE |
+                                                         G_PARAM_CONSTRUCT_ONLY));
+}
+
+static void
+gimp_mask_undo_init (GimpMaskUndo *undo)
+{
+}
+
+static void
+gimp_mask_undo_constructed (GObject *object)
+{
+  GimpMaskUndo *mask_undo = GIMP_MASK_UNDO (object);
+  GimpItem     *item;
+  GimpDrawable *drawable;
+
+  G_OBJECT_CLASS (parent_class)->constructed (object);
+
+  gimp_assert (GIMP_IS_CHANNEL (GIMP_ITEM_UNDO (object)->item));
+
+  item     = GIMP_ITEM_UNDO (object)->item;
+  drawable = GIMP_DRAWABLE (item);
+
+  mask_undo->format = gimp_drawable_get_format (drawable);
+
+  if (gimp_item_bounds (item,
+                        &mask_undo->bounds.x,
+                        &mask_undo->bounds.y,
+                        &mask_undo->bounds.width,
+                        &mask_undo->bounds.height))
+    {
+      GeglBuffer    *buffer = gimp_drawable_get_buffer (drawable);
+      GeglRectangle  rect;
+
+      gegl_rectangle_align_to_buffer (&rect, &mask_undo->bounds, buffer,
+                                      GEGL_RECTANGLE_ALIGNMENT_SUPERSET);
+
+      mask_undo->buffer = gegl_buffer_new (GEGL_RECTANGLE (0, 0,
+                                                           rect.width,
+                                                           rect.height),
+                                           mask_undo->format);
+
+      gimp_gegl_buffer_copy (buffer, &rect, GEGL_ABYSS_NONE,
+                             mask_undo->buffer, GEGL_RECTANGLE (0, 0, 0, 0));
+
+      mask_undo->x = rect.x;
+      mask_undo->y = rect.y;
+    }
+}
+
+static void
+gimp_mask_undo_set_property (GObject      *object,
+                             guint         property_id,
+                             const GValue *value,
+                             GParamSpec   *pspec)
+{
+  GimpMaskUndo *mask_undo = GIMP_MASK_UNDO (object);
+
+  switch (property_id)
+    {
+    case PROP_CONVERT_FORMAT:
+      mask_undo->convert_format = g_value_get_boolean (value);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_mask_undo_get_property (GObject    *object,
+                             guint       property_id,
+                             GValue     *value,
+                             GParamSpec *pspec)
+{
+  GimpMaskUndo *mask_undo = GIMP_MASK_UNDO (object);
+
+  switch (property_id)
+    {
+    case PROP_CONVERT_FORMAT:
+      g_value_set_boolean (value, mask_undo->convert_format);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static gint64
+gimp_mask_undo_get_memsize (GimpObject *object,
+                            gint64     *gui_size)
+{
+  GimpMaskUndo *mask_undo = GIMP_MASK_UNDO (object);
+  gint64        memsize   = 0;
+
+  memsize += gimp_gegl_buffer_get_memsize (mask_undo->buffer);
+
+  return memsize + GIMP_OBJECT_CLASS (parent_class)->get_memsize (object,
+                                                                  gui_size);
+}
+
+static void
+gimp_mask_undo_pop (GimpUndo            *undo,
+                    GimpUndoMode         undo_mode,
+                    GimpUndoAccumulator *accum)
+{
+  GimpMaskUndo  *mask_undo  = GIMP_MASK_UNDO (undo);
+  GimpItem      *item       = GIMP_ITEM_UNDO (undo)->item;
+  GimpDrawable  *drawable   = GIMP_DRAWABLE (item);
+  GimpChannel   *channel    = GIMP_CHANNEL (item);
+  GeglBuffer    *new_buffer = NULL;
+  GeglRectangle  bounds     = {};
+  GeglRectangle  rect       = {};
+  const Babl    *format;
+
+  GIMP_UNDO_CLASS (parent_class)->pop (undo, undo_mode, accum);
+
+  format = gimp_drawable_get_format (drawable);
+
+  if (gimp_item_bounds (item,
+                        &bounds.x,
+                        &bounds.y,
+                        &bounds.width,
+                        &bounds.height))
+    {
+      GeglBuffer *buffer = gimp_drawable_get_buffer (drawable);
+
+      gegl_rectangle_align_to_buffer (&rect, &bounds, buffer,
+                                      GEGL_RECTANGLE_ALIGNMENT_SUPERSET);
+
+      new_buffer = gegl_buffer_new (GEGL_RECTANGLE (0, 0,
+                                                    rect.width, rect.height),
+                                    format);
+
+      gimp_gegl_buffer_copy (buffer, &rect, GEGL_ABYSS_NONE,
+                             new_buffer, GEGL_RECTANGLE (0, 0, 0, 0));
+
+      gegl_buffer_clear (buffer, &rect);
+    }
+
+  if (mask_undo->convert_format)
+    {
+      GeglBuffer *buffer;
+      gint        width  = gimp_item_get_width  (item);
+      gint        height = gimp_item_get_height (item);
+
+      buffer = gegl_buffer_new (GEGL_RECTANGLE (0, 0, width, height),
+                                mask_undo->format);
+
+      gimp_drawable_set_buffer (drawable, FALSE, NULL, buffer);
+      g_object_unref (buffer);
+    }
+
+  if (mask_undo->buffer)
+    {
+      gimp_gegl_buffer_copy (mask_undo->buffer,
+                             NULL,
+                             GEGL_ABYSS_NONE,
+                             gimp_drawable_get_buffer (drawable),
+                             GEGL_RECTANGLE (mask_undo->x, mask_undo->y, 0, 0));
+
+      g_object_unref (mask_undo->buffer);
+    }
+
+  /* invalidate the current bounds and boundary of the mask */
+  gimp_drawable_invalidate_boundary (drawable);
+
+  if (mask_undo->buffer)
+    {
+      channel->empty = FALSE;
+      channel->x1    = mask_undo->bounds.x;
+      channel->y1    = mask_undo->bounds.y;
+      channel->x2    = mask_undo->bounds.x + mask_undo->bounds.width;
+      channel->y2    = mask_undo->bounds.y + mask_undo->bounds.height;
+    }
+  else
+    {
+      channel->empty = TRUE;
+      channel->x1    = 0;
+      channel->y1    = 0;
+      channel->x2    = gimp_item_get_width  (item);
+      channel->y2    = gimp_item_get_height (item);
+    }
+
+  /* we know the bounds */
+  channel->bounds_known = TRUE;
+
+  /*  set the new mask undo parameters  */
+  mask_undo->format = format;
+  mask_undo->buffer = new_buffer;
+  mask_undo->bounds = bounds;
+  mask_undo->x      = rect.x;
+  mask_undo->y      = rect.y;
+
+  gimp_drawable_update (drawable, 0, 0, -1, -1);
+}
+
+static void
+gimp_mask_undo_free (GimpUndo     *undo,
+                     GimpUndoMode  undo_mode)
+{
+  GimpMaskUndo *mask_undo = GIMP_MASK_UNDO (undo);
+
+  g_clear_object (&mask_undo->buffer);
+
+  GIMP_UNDO_CLASS (parent_class)->free (undo, undo_mode);
+}
diff --git a/app/core/gimpmaskundo.h b/app/core/gimpmaskundo.h
new file mode 100644
index 0000000..53b92e8
--- /dev/null
+++ b/app/core/gimpmaskundo.h
@@ -0,0 +1,58 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_MASK_UNDO_H__
+#define __GIMP_MASK_UNDO_H__
+
+
+#include "gimpitemundo.h"
+
+
+#define GIMP_TYPE_MASK_UNDO            (gimp_mask_undo_get_type ())
+#define GIMP_MASK_UNDO(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_MASK_UNDO, GimpMaskUndo))
+#define GIMP_MASK_UNDO_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_MASK_UNDO, GimpMaskUndoClass))
+#define GIMP_IS_MASK_UNDO(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_MASK_UNDO))
+#define GIMP_IS_MASK_UNDO_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_MASK_UNDO))
+#define GIMP_MASK_UNDO_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_MASK_UNDO, GimpMaskUndoClass))
+
+
+typedef struct _GimpMaskUndo      GimpMaskUndo;
+typedef struct _GimpMaskUndoClass GimpMaskUndoClass;
+
+struct _GimpMaskUndo
+{
+  GimpItemUndo   parent_instance;
+
+  gboolean       convert_format;
+
+  const Babl    *format;
+  GeglBuffer    *buffer;
+  GeglRectangle  bounds;
+  gint           x;
+  gint           y;
+};
+
+struct _GimpMaskUndoClass
+{
+  GimpItemUndoClass  parent_class;
+};
+
+
+GType   gimp_mask_undo_get_type (void) G_GNUC_CONST;
+
+
+#endif /* __GIMP_MASK_UNDO_H__ */
diff --git a/app/core/gimpmybrush-load.c b/app/core/gimpmybrush-load.c
new file mode 100644
index 0000000..1dbb9f5
--- /dev/null
+++ b/app/core/gimpmybrush-load.c
@@ -0,0 +1,153 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpmybrush-load.c
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include <mypaint-brush.h>
+
+#include "libgimpbase/gimpbase.h"
+
+#include "core-types.h"
+
+#include "gimpmybrush.h"
+#include "gimpmybrush-load.h"
+#include "gimpmybrush-private.h"
+
+#include "gimp-intl.h"
+
+
+/*  public functions  */
+
+GList *
+gimp_mybrush_load (GimpContext   *context,
+                   GFile         *file,
+                   GInputStream  *input,
+                   GError       **error)
+{
+  GimpMybrush  *brush = NULL;
+  MyPaintBrush *mypaint_brush;
+  GdkPixbuf    *pixbuf;
+  GFileInfo    *info;
+  guint64       size;
+  guchar       *buffer;
+  gchar        *path;
+  gchar        *basename;
+  gchar        *preview_filename;
+  gchar        *p;
+
+  g_return_val_if_fail (G_IS_FILE (file), NULL);
+  g_return_val_if_fail (G_IS_INPUT_STREAM (input), NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, NULL);
+
+  info = g_file_query_info (file,
+                            G_FILE_ATTRIBUTE_STANDARD_SIZE,
+                            G_FILE_QUERY_INFO_NONE,
+                            NULL, error);
+  if (! info)
+    return NULL;
+
+  size = g_file_info_get_attribute_uint64 (info,
+                                           G_FILE_ATTRIBUTE_STANDARD_SIZE);
+  g_object_unref (info);
+
+  if (size > 32768)
+    {
+      g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                   _("MyPaint brush file is unreasonably large, skipping."));
+      return NULL;
+    }
+
+  buffer = g_new0 (guchar, size + 1);
+
+  if (! g_input_stream_read_all (input, buffer, size, NULL, NULL, error))
+    {
+      g_free (buffer);
+      return NULL;
+    }
+
+  mypaint_brush = mypaint_brush_new ();
+  mypaint_brush_from_defaults (mypaint_brush);
+
+  if (! mypaint_brush_from_string (mypaint_brush, (const gchar *) buffer))
+    {
+      g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                   _("Failed to deserialize MyPaint brush."));
+      mypaint_brush_unref (mypaint_brush);
+      g_free (buffer);
+      return NULL;
+    }
+
+  path = g_file_get_path (file);
+  basename = g_strndup (path, strlen (path) - 4);
+  g_free (path);
+
+  preview_filename = g_strconcat (basename, "_prev.png", NULL);
+  g_free (basename);
+
+  pixbuf = gdk_pixbuf_new_from_file_at_size (preview_filename,
+                                             48, 48, error);
+  g_free (preview_filename);
+
+  basename = g_path_get_basename (gimp_file_get_utf8_name (file));
+
+  basename[strlen (basename) - 4] = '\0';
+  for (p = basename; *p; p++)
+    if (*p == '_' || *p == '-')
+      *p = ' ';
+
+  brush = g_object_new (GIMP_TYPE_MYBRUSH,
+                        "name",        basename,
+                        "mime-type",   "image/x-gimp-myb",
+                        "icon-pixbuf", pixbuf,
+                        NULL);
+
+  g_free (basename);
+
+  if (pixbuf)
+    g_object_unref (pixbuf);
+
+  brush->priv->brush_json = (gchar *) buffer;
+
+  brush->priv->radius =
+    mypaint_brush_get_base_value (mypaint_brush,
+                                  MYPAINT_BRUSH_SETTING_RADIUS_LOGARITHMIC);
+
+  brush->priv->opaque =
+    mypaint_brush_get_base_value (mypaint_brush,
+                                  MYPAINT_BRUSH_SETTING_OPAQUE);
+
+  brush->priv->hardness =
+    mypaint_brush_get_base_value (mypaint_brush,
+                                  MYPAINT_BRUSH_SETTING_HARDNESS);
+
+  brush->priv->eraser =
+    mypaint_brush_get_base_value (mypaint_brush,
+                                  MYPAINT_BRUSH_SETTING_ERASER) > 0.5f;
+
+  brush->priv->offset_by_random =
+    mypaint_brush_get_base_value (mypaint_brush,
+                                  MYPAINT_BRUSH_SETTING_OFFSET_BY_RANDOM);
+
+  mypaint_brush_unref (mypaint_brush);
+
+  return g_list_prepend (NULL, brush);
+}
diff --git a/app/core/gimpmybrush-load.h b/app/core/gimpmybrush-load.h
new file mode 100644
index 0000000..4afe203
--- /dev/null
+++ b/app/core/gimpmybrush-load.h
@@ -0,0 +1,33 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpmybrush-load.h
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_MYBRUSH_LOAD_H__
+#define __GIMP_MYBRUSH_LOAD_H__
+
+
+#define GIMP_MYBRUSH_FILE_EXTENSION ".myb"
+
+
+GList * gimp_mybrush_load (GimpContext   *context,
+                           GFile         *file,
+                           GInputStream  *input,
+                           GError       **error);
+
+
+#endif /* __GIMP_MYBRUSH_LOAD_H__ */
diff --git a/app/core/gimpmybrush-private.h b/app/core/gimpmybrush-private.h
new file mode 100644
index 0000000..7966c0b
--- /dev/null
+++ b/app/core/gimpmybrush-private.h
@@ -0,0 +1,35 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpmybrush-private.h
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_MYBRUSH_PRIVATE_H__
+#define __GIMP_MYBRUSH_PRIVATE_H__
+
+
+struct _GimpMybrushPrivate
+{
+  gchar   *brush_json;
+  gdouble  radius;
+  gdouble  opaque;
+  gdouble  hardness;
+  gdouble  offset_by_random;
+  gboolean eraser;
+};
+
+
+#endif /* __GIMP_MYBRUSH_PRIVATE_H__ */
diff --git a/app/core/gimpmybrush.c b/app/core/gimpmybrush.c
new file mode 100644
index 0000000..a26c86b
--- /dev/null
+++ b/app/core/gimpmybrush.c
@@ -0,0 +1,281 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpmybrush.c
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <cairo.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gimp-memsize.h"
+#include "gimpmybrush.h"
+#include "gimpmybrush-load.h"
+#include "gimpmybrush-private.h"
+#include "gimptagged.h"
+
+#include "gimp-intl.h"
+
+
+static void          gimp_mybrush_tagged_iface_init     (GimpTaggedInterface  *iface);
+
+static void          gimp_mybrush_finalize              (GObject              *object);
+static void          gimp_mybrush_set_property          (GObject              *object,
+                                                         guint                 property_id,
+                                                         const GValue         *value,
+                                                         GParamSpec           *pspec);
+static void          gimp_mybrush_get_property          (GObject              *object,
+                                                         guint                 property_id,
+                                                         GValue               *value,
+                                                         GParamSpec           *pspec);
+
+static gint64        gimp_mybrush_get_memsize           (GimpObject           *object,
+                                                         gint64               *gui_size);
+
+static gchar       * gimp_mybrush_get_description       (GimpViewable         *viewable,
+                                                         gchar               **tooltip);
+
+static void          gimp_mybrush_dirty                 (GimpData             *data);
+static const gchar * gimp_mybrush_get_extension         (GimpData             *data);
+
+static gchar       * gimp_mybrush_get_checksum          (GimpTagged           *tagged);
+
+
+G_DEFINE_TYPE_WITH_CODE (GimpMybrush, gimp_mybrush, GIMP_TYPE_DATA,
+                         G_ADD_PRIVATE (GimpMybrush)
+                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_TAGGED,
+                                                gimp_mybrush_tagged_iface_init))
+
+#define parent_class gimp_mybrush_parent_class
+
+
+static void
+gimp_mybrush_class_init (GimpMybrushClass *klass)
+{
+  GObjectClass      *object_class      = G_OBJECT_CLASS (klass);
+  GimpObjectClass   *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+  GimpViewableClass *viewable_class    = GIMP_VIEWABLE_CLASS (klass);
+  GimpDataClass     *data_class        = GIMP_DATA_CLASS (klass);
+
+  object_class->finalize            = gimp_mybrush_finalize;
+  object_class->get_property        = gimp_mybrush_get_property;
+  object_class->set_property        = gimp_mybrush_set_property;
+
+  gimp_object_class->get_memsize    = gimp_mybrush_get_memsize;
+
+  viewable_class->default_icon_name = "gimp-tool-mypaint-brush";
+  viewable_class->get_description   = gimp_mybrush_get_description;
+
+  data_class->dirty                 = gimp_mybrush_dirty;
+  data_class->get_extension         = gimp_mybrush_get_extension;
+}
+
+static void
+gimp_mybrush_tagged_iface_init (GimpTaggedInterface *iface)
+{
+  iface->get_checksum = gimp_mybrush_get_checksum;
+}
+
+static void
+gimp_mybrush_init (GimpMybrush *brush)
+{
+  brush->priv = gimp_mybrush_get_instance_private (brush);
+
+  brush->priv->radius   = 1.0;
+  brush->priv->opaque   = 1.0;
+  brush->priv->hardness = 1.0;
+  brush->priv->eraser   = FALSE;
+}
+
+static void
+gimp_mybrush_finalize (GObject *object)
+{
+  GimpMybrush *brush = GIMP_MYBRUSH (object);
+
+  g_clear_pointer (&brush->priv->brush_json, g_free);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gimp_mybrush_set_property (GObject      *object,
+                           guint         property_id,
+                           const GValue *value,
+                           GParamSpec   *pspec)
+{
+  switch (property_id)
+    {
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_mybrush_get_property (GObject    *object,
+                           guint       property_id,
+                           GValue     *value,
+                           GParamSpec *pspec)
+{
+  switch (property_id)
+    {
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static gint64
+gimp_mybrush_get_memsize (GimpObject *object,
+                          gint64     *gui_size)
+{
+  GimpMybrush *brush   = GIMP_MYBRUSH (object);
+  gint64       memsize = 0;
+
+  memsize += gimp_string_get_memsize (brush->priv->brush_json);
+
+  return memsize + GIMP_OBJECT_CLASS (parent_class)->get_memsize (object,
+                                                                  gui_size);
+}
+
+static gchar *
+gimp_mybrush_get_description (GimpViewable  *viewable,
+                              gchar        **tooltip)
+{
+  GimpMybrush *brush = GIMP_MYBRUSH (viewable);
+
+  return g_strdup_printf ("%s",
+                          gimp_object_get_name (brush));
+}
+
+static void
+gimp_mybrush_dirty (GimpData *data)
+{
+  GIMP_DATA_CLASS (parent_class)->dirty (data);
+}
+
+static const gchar *
+gimp_mybrush_get_extension (GimpData *data)
+{
+  return GIMP_MYBRUSH_FILE_EXTENSION;
+}
+
+static gchar *
+gimp_mybrush_get_checksum (GimpTagged *tagged)
+{
+  GimpMybrush *brush           = GIMP_MYBRUSH (tagged);
+  gchar       *checksum_string = NULL;
+
+  if (brush->priv->brush_json)
+    {
+      GChecksum *checksum = g_checksum_new (G_CHECKSUM_MD5);
+
+      g_checksum_update (checksum,
+                         (const guchar *) brush->priv->brush_json,
+                         strlen (brush->priv->brush_json));
+
+      checksum_string = g_strdup (g_checksum_get_string (checksum));
+
+      g_checksum_free (checksum);
+    }
+
+  return checksum_string;
+}
+
+/*  public functions  */
+
+GimpData *
+gimp_mybrush_new (GimpContext *context,
+                  const gchar *name)
+{
+  g_return_val_if_fail (name != NULL, NULL);
+
+  return g_object_new (GIMP_TYPE_MYBRUSH,
+                       "name",      name,
+                       "mime-type", "image/x-gimp-myb",
+                       NULL);
+}
+
+GimpData *
+gimp_mybrush_get_standard (GimpContext *context)
+{
+  static GimpData *standard_mybrush = NULL;
+
+  if (! standard_mybrush)
+    {
+      standard_mybrush = gimp_mybrush_new (context, "Standard");
+
+      gimp_data_clean (standard_mybrush);
+      gimp_data_make_internal (standard_mybrush, "gimp-mybrush-standard");
+
+      g_object_add_weak_pointer (G_OBJECT (standard_mybrush),
+                                 (gpointer *) &standard_mybrush);
+    }
+
+  return standard_mybrush;
+}
+
+const gchar *
+gimp_mybrush_get_brush_json (GimpMybrush *brush)
+{
+  g_return_val_if_fail (GIMP_IS_MYBRUSH (brush), NULL);
+
+  return brush->priv->brush_json;
+}
+
+gdouble
+gimp_mybrush_get_radius (GimpMybrush *brush)
+{
+  g_return_val_if_fail (GIMP_IS_MYBRUSH (brush), 1.0);
+
+  return brush->priv->radius;
+}
+
+gdouble
+gimp_mybrush_get_opaque (GimpMybrush *brush)
+{
+  g_return_val_if_fail (GIMP_IS_MYBRUSH (brush), 1.0);
+
+  return brush->priv->opaque;
+}
+
+gdouble
+gimp_mybrush_get_hardness (GimpMybrush *brush)
+{
+  g_return_val_if_fail (GIMP_IS_MYBRUSH (brush), 1.0);
+
+  return brush->priv->hardness;
+}
+
+gdouble
+gimp_mybrush_get_offset_by_random (GimpMybrush *brush)
+{
+  g_return_val_if_fail (GIMP_IS_MYBRUSH (brush), 1.0);
+
+  return brush->priv->offset_by_random;
+}
+
+gboolean
+gimp_mybrush_get_is_eraser (GimpMybrush *brush)
+{
+  g_return_val_if_fail (GIMP_IS_MYBRUSH (brush), FALSE);
+
+  return brush->priv->eraser;
+}
diff --git a/app/core/gimpmybrush.h b/app/core/gimpmybrush.h
new file mode 100644
index 0000000..2dad734
--- /dev/null
+++ b/app/core/gimpmybrush.h
@@ -0,0 +1,66 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpmybrush.h
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_MYBRUSH_H__
+#define __GIMP_MYBRUSH_H__
+
+
+#include "gimpdata.h"
+
+
+#define GIMP_TYPE_MYBRUSH            (gimp_mybrush_get_type ())
+#define GIMP_MYBRUSH(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_MYBRUSH, GimpMybrush))
+#define GIMP_MYBRUSH_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_MYBRUSH, GimpMybrushClass))
+#define GIMP_IS_MYBRUSH(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_MYBRUSH))
+#define GIMP_IS_MYBRUSH_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_MYBRUSH))
+#define GIMP_MYBRUSH_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_MYBRUSH, GimpMybrushClass))
+
+
+typedef struct _GimpMybrushPrivate GimpMybrushPrivate;
+typedef struct _GimpMybrushClass   GimpMybrushClass;
+
+struct _GimpMybrush
+{
+  GimpData            parent_instance;
+
+  GimpMybrushPrivate *priv;
+};
+
+struct _GimpMybrushClass
+{
+  GimpDataClass  parent_class;
+};
+
+
+GType         gimp_mybrush_get_type             (void) G_GNUC_CONST;
+
+GimpData    * gimp_mybrush_new                  (GimpContext *context,
+                                                 const gchar *name);
+GimpData    * gimp_mybrush_get_standard         (GimpContext *context);
+
+const gchar * gimp_mybrush_get_brush_json       (GimpMybrush *brush);
+
+gdouble       gimp_mybrush_get_radius           (GimpMybrush *brush);
+gdouble       gimp_mybrush_get_opaque           (GimpMybrush *brush);
+gdouble       gimp_mybrush_get_hardness         (GimpMybrush *brush);
+gdouble       gimp_mybrush_get_offset_by_random (GimpMybrush *brush);
+gboolean      gimp_mybrush_get_is_eraser        (GimpMybrush *brush);
+
+
+#endif /* __GIMP_MYBRUSH_H__ */
diff --git a/app/core/gimpobject.c b/app/core/gimpobject.c
new file mode 100644
index 0000000..0f3baf7
--- /dev/null
+++ b/app/core/gimpobject.c
@@ -0,0 +1,512 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1997 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <gio/gio.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+
+#include "core-types.h"
+
+#include "gimp-memsize.h"
+#include "gimpmarshal.h"
+#include "gimpobject.h"
+
+#include "gimp-debug.h"
+
+
+enum
+{
+  DISCONNECT,
+  NAME_CHANGED,
+  LAST_SIGNAL
+};
+
+enum
+{
+  PROP_0,
+  PROP_NAME
+};
+
+
+struct _GimpObjectPrivate
+{
+  gchar *name;
+  gchar *normalized;
+  guint  static_name  : 1;
+  guint  disconnected : 1;
+};
+
+
+static void    gimp_object_constructed      (GObject         *object);
+static void    gimp_object_dispose          (GObject         *object);
+static void    gimp_object_finalize         (GObject         *object);
+static void    gimp_object_set_property     (GObject         *object,
+                                             guint            property_id,
+                                             const GValue    *value,
+                                             GParamSpec      *pspec);
+static void    gimp_object_get_property     (GObject         *object,
+                                             guint            property_id,
+                                             GValue          *value,
+                                             GParamSpec      *pspec);
+static gint64  gimp_object_real_get_memsize (GimpObject      *object,
+                                             gint64          *gui_size);
+static void    gimp_object_name_normalize   (GimpObject      *object);
+
+
+G_DEFINE_TYPE_WITH_CODE (GimpObject, gimp_object, G_TYPE_OBJECT,
+                         G_ADD_PRIVATE (GimpObject))
+
+#define parent_class gimp_object_parent_class
+
+static guint object_signals[LAST_SIGNAL] = { 0 };
+
+
+static void
+gimp_object_class_init (GimpObjectClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  parent_class = g_type_class_peek_parent (klass);
+
+  object_signals[DISCONNECT] =
+    g_signal_new ("disconnect",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpObjectClass, disconnect),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  object_signals[NAME_CHANGED] =
+    g_signal_new ("name-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpObjectClass, name_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  object_class->constructed  = gimp_object_constructed;
+  object_class->dispose      = gimp_object_dispose;
+  object_class->finalize     = gimp_object_finalize;
+  object_class->set_property = gimp_object_set_property;
+  object_class->get_property = gimp_object_get_property;
+
+  klass->disconnect          = NULL;
+  klass->name_changed        = NULL;
+  klass->get_memsize         = gimp_object_real_get_memsize;
+
+  g_object_class_install_property (object_class, PROP_NAME,
+                                   g_param_spec_string ("name",
+                                                        NULL, NULL,
+                                                        NULL,
+                                                        GIMP_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT));
+}
+
+static void
+gimp_object_init (GimpObject *object)
+{
+  object->p = gimp_object_get_instance_private (object);
+
+  object->p->name       = NULL;
+  object->p->normalized = NULL;
+}
+
+static void
+gimp_object_constructed (GObject *object)
+{
+  G_OBJECT_CLASS (parent_class)->constructed (object);
+
+  gimp_debug_add_instance (object, G_OBJECT_GET_CLASS (object));
+}
+
+static void
+gimp_object_dispose (GObject *object)
+{
+  GimpObject *gimp_object = GIMP_OBJECT (object);
+
+  if (! gimp_object->p->disconnected)
+    {
+      g_signal_emit (object, object_signals[DISCONNECT], 0);
+
+      gimp_object->p->disconnected = TRUE;
+    }
+
+  G_OBJECT_CLASS (parent_class)->dispose (object);
+}
+
+static void
+gimp_object_finalize (GObject *object)
+{
+  gimp_object_name_free (GIMP_OBJECT (object));
+
+  gimp_debug_remove_instance (object);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gimp_object_set_property (GObject      *object,
+                          guint         property_id,
+                          const GValue *value,
+                          GParamSpec   *pspec)
+{
+  GimpObject *gimp_object = GIMP_OBJECT (object);
+
+  switch (property_id)
+    {
+    case PROP_NAME:
+      gimp_object_set_name (gimp_object, g_value_get_string (value));
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_object_get_property (GObject    *object,
+                          guint       property_id,
+                          GValue     *value,
+                          GParamSpec *pspec)
+{
+  GimpObject *gimp_object = GIMP_OBJECT (object);
+
+  switch (property_id)
+    {
+    case PROP_NAME:
+      if (gimp_object->p->static_name)
+        g_value_set_static_string (value, gimp_object->p->name);
+      else
+        g_value_set_string (value, gimp_object->p->name);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+/**
+ * gimp_object_set_name:
+ * @object: a #GimpObject
+ * @name: the @object's new name
+ *
+ * Sets the @object's name. Takes care of freeing the old name and
+ * emitting the ::name_changed signal if the old and new name differ.
+ **/
+void
+gimp_object_set_name (GimpObject  *object,
+                      const gchar *name)
+{
+  g_return_if_fail (GIMP_IS_OBJECT (object));
+
+  if (! g_strcmp0 (object->p->name, name))
+    return;
+
+  gimp_object_name_free (object);
+
+  object->p->name = g_strdup (name);
+  object->p->static_name = FALSE;
+
+  gimp_object_name_changed (object);
+  g_object_notify (G_OBJECT (object), "name");
+}
+
+/**
+ * gimp_object_set_name_safe:
+ * @object: a #GimpObject
+ * @name: the @object's new name
+ *
+ * A safe version of gimp_object_set_name() that takes care of
+ * handling newlines and overly long names. The actual name set
+ * may be different to the @name you pass.
+ **/
+void
+gimp_object_set_name_safe (GimpObject  *object,
+                           const gchar *name)
+{
+  g_return_if_fail (GIMP_IS_OBJECT (object));
+
+  if (! g_strcmp0 (object->p->name, name))
+    return;
+
+  gimp_object_name_free (object);
+
+  object->p->name = gimp_utf8_strtrim (name, 30);
+  object->p->static_name = FALSE;
+
+  gimp_object_name_changed (object);
+  g_object_notify (G_OBJECT (object), "name");
+}
+
+void
+gimp_object_set_static_name (GimpObject  *object,
+                             const gchar *name)
+{
+  g_return_if_fail (GIMP_IS_OBJECT (object));
+
+  if (! g_strcmp0 (object->p->name, name))
+    return;
+
+  gimp_object_name_free (object);
+
+  object->p->name = (gchar *) name;
+  object->p->static_name = TRUE;
+
+  gimp_object_name_changed (object);
+  g_object_notify (G_OBJECT (object), "name");
+}
+
+void
+gimp_object_take_name (GimpObject *object,
+                       gchar      *name)
+{
+  g_return_if_fail (GIMP_IS_OBJECT (object));
+
+  if (! g_strcmp0 (object->p->name, name))
+    {
+      g_free (name);
+      return;
+    }
+
+  gimp_object_name_free (object);
+
+  object->p->name = name;
+  object->p->static_name = FALSE;
+
+  gimp_object_name_changed (object);
+  g_object_notify (G_OBJECT (object), "name");
+}
+
+/**
+ * gimp_object_get_name:
+ * @object: a #GimpObject
+ *
+ * This function gives access to the name of a GimpObject. The
+ * returned name belongs to the object and must not be freed.
+ *
+ * Return value: a pointer to the @object's name
+ **/
+const gchar *
+gimp_object_get_name (gconstpointer object)
+{
+  const GimpObject *object_typed = object;
+  g_return_val_if_fail (GIMP_IS_OBJECT (object_typed), NULL);
+
+  return object_typed->p->name;
+}
+
+/**
+ * gimp_object_name_changed:
+ * @object: a #GimpObject
+ *
+ * Causes the ::name-changed signal to be emitted.
+ **/
+void
+gimp_object_name_changed (GimpObject *object)
+{
+  g_return_if_fail (GIMP_IS_OBJECT (object));
+
+  g_signal_emit (object, object_signals[NAME_CHANGED], 0);
+}
+
+/**
+ * gimp_object_name_free:
+ * @object: a #GimpObject
+ *
+ * Frees the name of @object and sets the name pointer to %NULL. Also
+ * takes care of the normalized name that the object might be caching.
+ *
+ * In general you should be using gimp_object_set_name() instead. But
+ * if you ever need to free the object name but don't want the
+ * ::name-changed signal to be emitted, then use this function. Never
+ * ever free the object name directly!
+ **/
+void
+gimp_object_name_free (GimpObject *object)
+{
+  if (object->p->normalized)
+    {
+      if (object->p->normalized != object->p->name)
+        g_free (object->p->normalized);
+
+      object->p->normalized = NULL;
+    }
+
+  if (object->p->name)
+    {
+      if (! object->p->static_name)
+        g_free (object->p->name);
+
+      object->p->name = NULL;
+      object->p->static_name = FALSE;
+    }
+}
+
+/**
+ * gimp_object_name_collate:
+ * @object1: a #GimpObject
+ * @object2: another #GimpObject
+ *
+ * Compares two object names for ordering using the linguistically
+ * correct rules for the current locale. It caches the normalized
+ * version of the object name to speed up subsequent calls.
+ *
+ * Return value: -1 if object1 compares before object2,
+ *                0 if they compare equal,
+ *                1 if object1 compares after object2.
+ **/
+gint
+gimp_object_name_collate (GimpObject *object1,
+                          GimpObject *object2)
+{
+  if (! object1->p->normalized)
+    gimp_object_name_normalize (object1);
+
+  if (! object2->p->normalized)
+    gimp_object_name_normalize (object2);
+
+  return strcmp (object1->p->normalized, object2->p->normalized);
+}
+
+static void
+gimp_object_name_normalize (GimpObject *object)
+{
+  g_return_if_fail (object->p->normalized == NULL);
+
+  if (object->p->name)
+    {
+      gchar *key = g_utf8_collate_key (object->p->name, -1);
+
+      if (strcmp (key, object->p->name))
+        {
+          object->p->normalized = key;
+        }
+      else
+        {
+          g_free (key);
+          object->p->normalized = object->p->name;
+        }
+    }
+}
+
+
+#define DEBUG_MEMSIZE 1
+
+#ifdef DEBUG_MEMSIZE
+gboolean gimp_debug_memsize = FALSE;
+#endif
+
+gint64
+gimp_object_get_memsize (GimpObject *object,
+                         gint64     *gui_size)
+{
+  gint64 my_size     = 0;
+  gint64 my_gui_size = 0;
+
+  g_return_val_if_fail (object == NULL || GIMP_IS_OBJECT (object), 0);
+
+  if (! object)
+    {
+      if (gui_size)
+        *gui_size = 0;
+
+      return 0;
+    }
+
+#ifdef DEBUG_MEMSIZE
+  if (gimp_debug_memsize)
+    {
+      static gint   indent_level     = 0;
+      static GList *aggregation_tree = NULL;
+      static gchar  indent_buf[256];
+
+      gint64  memsize;
+      gint64  gui_memsize = 0;
+      gint    i;
+      gint    my_indent_level;
+      gchar  *object_size;
+
+      indent_level++;
+
+      my_indent_level = indent_level;
+
+      memsize = GIMP_OBJECT_GET_CLASS (object)->get_memsize (object,
+                                                             &gui_memsize);
+
+      indent_level--;
+
+      for (i = 0; i < MIN (my_indent_level * 2, sizeof (indent_buf) - 1); i++)
+        indent_buf[i] = ' ';
+
+      indent_buf[i] = '\0';
+
+      object_size = g_strdup_printf ("%s%s \"%s\": "
+                                     "%" G_GINT64_FORMAT
+                                     "(%" G_GINT64_FORMAT ")\n",
+                                     indent_buf,
+                                     g_type_name (G_TYPE_FROM_INSTANCE (object)),
+                                     object->p->name ? object->p->name : "anonymous",
+                                     memsize,
+                                     gui_memsize);
+
+      aggregation_tree = g_list_prepend (aggregation_tree, object_size);
+
+      if (indent_level == 0)
+        {
+          GList *list;
+
+          for (list = aggregation_tree; list; list = g_list_next (list))
+            {
+              g_print ("%s", (gchar *) list->data);
+              g_free (list->data);
+            }
+
+          g_list_free (aggregation_tree);
+          aggregation_tree = NULL;
+        }
+
+      return memsize;
+    }
+#endif /* DEBUG_MEMSIZE */
+
+  my_size = GIMP_OBJECT_GET_CLASS (object)->get_memsize (object,
+                                                         &my_gui_size);
+
+  if (gui_size)
+    *gui_size = my_gui_size;
+
+  return my_size;
+}
+
+static gint64
+gimp_object_real_get_memsize (GimpObject *object,
+                              gint64     *gui_size)
+{
+  gint64 memsize = 0;
+
+  if (! object->p->static_name)
+    memsize += gimp_string_get_memsize (object->p->name);
+
+  return memsize + gimp_g_object_get_memsize ((GObject *) object);
+}
diff --git a/app/core/gimpobject.h b/app/core/gimpobject.h
new file mode 100644
index 0000000..17401c5
--- /dev/null
+++ b/app/core/gimpobject.h
@@ -0,0 +1,74 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1997 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_OBJECT_H__
+#define __GIMP_OBJECT_H__
+
+
+#define GIMP_TYPE_OBJECT            (gimp_object_get_type ())
+#define GIMP_OBJECT(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_OBJECT, GimpObject))
+#define GIMP_OBJECT_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_OBJECT, GimpObjectClass))
+#define GIMP_IS_OBJECT(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_OBJECT))
+#define GIMP_IS_OBJECT_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_OBJECT))
+#define GIMP_OBJECT_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_OBJECT, GimpObjectClass))
+
+
+typedef struct _GimpObjectPrivate  GimpObjectPrivate;
+typedef struct _GimpObjectClass    GimpObjectClass;
+
+struct _GimpObject
+{
+  GObject            parent_instance;
+
+  GimpObjectPrivate *p;
+};
+
+struct _GimpObjectClass
+{
+  GObjectClass  parent_class;
+
+  /*  signals  */
+  void    (* disconnect)   (GimpObject *object);
+  void    (* name_changed) (GimpObject *object);
+
+  /*  virtual functions  */
+  gint64  (* get_memsize)  (GimpObject *object,
+                            gint64     *gui_size);
+};
+
+
+GType         gimp_object_get_type        (void) G_GNUC_CONST;
+
+void          gimp_object_set_name        (GimpObject       *object,
+                                           const gchar      *name);
+void          gimp_object_set_name_safe   (GimpObject       *object,
+                                           const gchar      *name);
+void          gimp_object_set_static_name (GimpObject       *object,
+                                           const gchar      *name);
+void          gimp_object_take_name       (GimpObject       *object,
+                                           gchar            *name);
+const gchar * gimp_object_get_name        (gconstpointer     object);
+void          gimp_object_name_changed    (GimpObject       *object);
+void          gimp_object_name_free       (GimpObject       *object);
+
+gint          gimp_object_name_collate    (GimpObject       *object1,
+                                           GimpObject       *object2);
+gint64        gimp_object_get_memsize     (GimpObject       *object,
+                                           gint64           *gui_size);
+
+
+#endif  /* __GIMP_OBJECT_H__ */
diff --git a/app/core/gimpobjectqueue.c b/app/core/gimpobjectqueue.c
new file mode 100644
index 0000000..edadc09
--- /dev/null
+++ b/app/core/gimpobjectqueue.c
@@ -0,0 +1,198 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <glib-object.h>
+
+#include "core-types.h"
+
+#include "gimpcontainer.h"
+#include "gimpobject.h"
+#include "gimpobjectqueue.h"
+#include "gimpprogress.h"
+
+
+typedef struct
+{
+  GimpObject *object;
+  gint64      memsize;
+} Item;
+
+
+static void   gimp_object_queue_dispose      (GObject         *object);
+
+static void   gimp_object_queue_push_swapped (gpointer         object,
+                                              GimpObjectQueue *queue);
+
+static Item * gimp_object_queue_item_new     (GimpObject      *object);
+static void   gimp_object_queue_item_free    (Item            *item);
+
+
+G_DEFINE_TYPE (GimpObjectQueue, gimp_object_queue, GIMP_TYPE_SUB_PROGRESS);
+
+#define parent_class gimp_object_queue_parent_class
+
+
+/*  private functions  */
+
+
+static void
+gimp_object_queue_class_init (GimpObjectQueueClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  object_class->dispose = gimp_object_queue_dispose;
+}
+
+static void
+gimp_object_queue_init (GimpObjectQueue *queue)
+{
+  g_queue_init (&queue->items);
+
+  queue->processed_memsize = 0;
+  queue->total_memsize     = 0;
+}
+
+static void
+gimp_object_queue_dispose (GObject *object)
+{
+  gimp_object_queue_clear (GIMP_OBJECT_QUEUE (object));
+
+  G_OBJECT_CLASS (parent_class)->dispose (object);
+}
+
+static void
+gimp_object_queue_push_swapped (gpointer         object,
+                                GimpObjectQueue *queue)
+{
+  gimp_object_queue_push (queue, object);
+}
+
+static Item *
+gimp_object_queue_item_new (GimpObject *object)
+{
+  Item *item = g_slice_new (Item);
+
+  item->object  = object;
+  item->memsize = gimp_object_get_memsize (object, NULL);
+
+  return item;
+}
+
+static void
+gimp_object_queue_item_free (Item *item)
+{
+  g_slice_free (Item, item);
+}
+
+
+/*  public functions  */
+
+
+GimpObjectQueue *
+gimp_object_queue_new (GimpProgress *progress)
+{
+  g_return_val_if_fail (progress == NULL || GIMP_IS_PROGRESS (progress), NULL);
+
+  return g_object_new (GIMP_TYPE_OBJECT_QUEUE,
+                       "progress", progress,
+                       NULL);
+}
+
+void
+gimp_object_queue_clear (GimpObjectQueue *queue)
+{
+  Item *item;
+
+  g_return_if_fail (GIMP_IS_OBJECT_QUEUE (queue));
+
+  while ((item = g_queue_pop_head (&queue->items)))
+    gimp_object_queue_item_free (item);
+
+  queue->processed_memsize = 0;
+  queue->total_memsize     = 0;
+
+  gimp_sub_progress_set_range (GIMP_SUB_PROGRESS (queue), 0.0, 1.0);
+}
+
+void
+gimp_object_queue_push (GimpObjectQueue *queue,
+                        gpointer         object)
+{
+  Item *item;
+
+  g_return_if_fail (GIMP_IS_OBJECT_QUEUE (queue));
+  g_return_if_fail (GIMP_IS_OBJECT (object));
+
+  item = gimp_object_queue_item_new (GIMP_OBJECT (object));
+
+  g_queue_push_tail (&queue->items, item);
+
+  queue->total_memsize += item->memsize;
+}
+
+void
+gimp_object_queue_push_container (GimpObjectQueue *queue,
+                                  GimpContainer   *container)
+{
+  g_return_if_fail (GIMP_IS_OBJECT_QUEUE (queue));
+  g_return_if_fail (GIMP_IS_CONTAINER (container));
+
+  gimp_container_foreach (container,
+                          (GFunc) gimp_object_queue_push_swapped,
+                          queue);
+}
+
+void
+gimp_object_queue_push_list (GimpObjectQueue *queue,
+                             GList           *list)
+{
+  g_return_if_fail (GIMP_IS_OBJECT_QUEUE (queue));
+
+  g_list_foreach (list,
+                  (GFunc) gimp_object_queue_push_swapped,
+                  queue);
+}
+
+gpointer
+gimp_object_queue_pop (GimpObjectQueue *queue)
+{
+  Item       *item;
+  GimpObject *object;
+
+  g_return_val_if_fail (GIMP_IS_OBJECT_QUEUE (queue), NULL);
+
+  item = g_queue_pop_head (&queue->items);
+
+  if (! item)
+    return NULL;
+
+  object = item->object;
+
+  gimp_sub_progress_set_range (GIMP_SUB_PROGRESS (queue),
+                               (gdouble) queue->processed_memsize  /
+                               (gdouble) queue->total_memsize,
+                               (gdouble) (queue->processed_memsize +
+                                          item->memsize)              /
+                               (gdouble) queue->total_memsize);
+  queue->processed_memsize += item->memsize;
+
+  gimp_object_queue_item_free (item);
+
+  return object;
+}
diff --git a/app/core/gimpobjectqueue.h b/app/core/gimpobjectqueue.h
new file mode 100644
index 0000000..024754f
--- /dev/null
+++ b/app/core/gimpobjectqueue.h
@@ -0,0 +1,66 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_OBJECT_QUEUE_H__
+#define __GIMP_OBJECT_QUEUE_H__
+
+
+#include "gimpsubprogress.h"
+
+
+#define GIMP_TYPE_OBJECT_QUEUE            (gimp_object_queue_get_type ())
+#define GIMP_OBJECT_QUEUE(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_OBJECT_QUEUE, GimpObjectQueue))
+#define GIMP_OBJECT_QUEUE_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_OBJECT_QUEUE, GimpObjectQueueClass))
+#define GIMP_IS_OBJECT_QUEUE(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_OBJECT_QUEUE))
+#define GIMP_IS_OBJECT_QUEUE_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_OBJECT_QUEUE))
+#define GIMP_OBJECT_QUEUE_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_OBJECT_QUEUE, GimpObjectQueueClass))
+
+
+typedef struct _GimpObjectQueueClass GimpObjectQueueClass;
+
+struct _GimpObjectQueue
+{
+  GimpSubProgress  parent_instance;
+
+  GQueue           items;
+  gint64           processed_memsize;
+  gint64           total_memsize;
+};
+
+struct _GimpObjectQueueClass
+{
+  GimpSubProgressClass  parent_class;
+};
+
+
+GType             gimp_object_queue_get_type       (void) G_GNUC_CONST;
+
+GimpObjectQueue * gimp_object_queue_new            (GimpProgress    *progress);
+
+void              gimp_object_queue_clear          (GimpObjectQueue *queue);
+
+void              gimp_object_queue_push           (GimpObjectQueue *queue,
+                                                    gpointer         object);
+void              gimp_object_queue_push_container (GimpObjectQueue *queue,
+                                                    GimpContainer   *container);
+void              gimp_object_queue_push_list      (GimpObjectQueue *queue,
+                                                    GList           *list);
+
+gpointer          gimp_object_queue_pop            (GimpObjectQueue *queue);
+
+
+#endif /* __GIMP_OBJECT_QUEUE_H__ */
diff --git a/app/core/gimppaintinfo.c b/app/core/gimppaintinfo.c
new file mode 100644
index 0000000..c7d6d81
--- /dev/null
+++ b/app/core/gimppaintinfo.c
@@ -0,0 +1,142 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "paint/gimppaintoptions.h"
+
+#include "gimp.h"
+#include "gimppaintinfo.h"
+
+
+static void    gimp_paint_info_dispose         (GObject       *object);
+static void    gimp_paint_info_finalize        (GObject       *object);
+static gchar * gimp_paint_info_get_description (GimpViewable  *viewable,
+                                                gchar        **tooltip);
+
+
+G_DEFINE_TYPE (GimpPaintInfo, gimp_paint_info, GIMP_TYPE_VIEWABLE)
+
+#define parent_class gimp_paint_info_parent_class
+
+
+static void
+gimp_paint_info_class_init (GimpPaintInfoClass *klass)
+{
+  GObjectClass      *object_class   = G_OBJECT_CLASS (klass);
+  GimpViewableClass *viewable_class = GIMP_VIEWABLE_CLASS (klass);
+
+  object_class->dispose           = gimp_paint_info_dispose;
+  object_class->finalize          = gimp_paint_info_finalize;
+
+  viewable_class->get_description = gimp_paint_info_get_description;
+}
+
+static void
+gimp_paint_info_init (GimpPaintInfo *paint_info)
+{
+  paint_info->gimp          = NULL;
+  paint_info->paint_type    = G_TYPE_NONE;
+  paint_info->blurb         = NULL;
+  paint_info->paint_options = NULL;
+}
+
+static void
+gimp_paint_info_dispose (GObject *object)
+{
+  GimpPaintInfo *paint_info = GIMP_PAINT_INFO (object);
+
+  if (paint_info->paint_options)
+    {
+      g_object_run_dispose (G_OBJECT (paint_info->paint_options));
+      g_clear_object (&paint_info->paint_options);
+    }
+
+  G_OBJECT_CLASS (parent_class)->dispose (object);
+}
+
+static void
+gimp_paint_info_finalize (GObject *object)
+{
+  GimpPaintInfo *paint_info = GIMP_PAINT_INFO (object);
+
+  g_clear_pointer (&paint_info->blurb, g_free);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static gchar *
+gimp_paint_info_get_description (GimpViewable  *viewable,
+                                 gchar        **tooltip)
+{
+  GimpPaintInfo *paint_info = GIMP_PAINT_INFO (viewable);
+
+  return g_strdup (paint_info->blurb);
+}
+
+GimpPaintInfo *
+gimp_paint_info_new (Gimp        *gimp,
+                     GType        paint_type,
+                     GType        paint_options_type,
+                     const gchar *identifier,
+                     const gchar *blurb,
+                     const gchar *icon_name)
+{
+  GimpPaintInfo *paint_info;
+
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+  g_return_val_if_fail (identifier != NULL, NULL);
+  g_return_val_if_fail (blurb != NULL, NULL);
+  g_return_val_if_fail (icon_name != NULL, NULL);
+
+  paint_info = g_object_new (GIMP_TYPE_PAINT_INFO,
+                             "name",      identifier,
+                             "icon-name", icon_name,
+                             NULL);
+
+  paint_info->gimp               = gimp;
+  paint_info->paint_type         = paint_type;
+  paint_info->paint_options_type = paint_options_type;
+  paint_info->blurb              = g_strdup (blurb);
+
+  paint_info->paint_options      = gimp_paint_options_new (paint_info);
+
+  return paint_info;
+}
+
+void
+gimp_paint_info_set_standard (Gimp          *gimp,
+                              GimpPaintInfo *paint_info)
+{
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+  g_return_if_fail (! paint_info || GIMP_IS_PAINT_INFO (paint_info));
+
+  g_set_object (&gimp->standard_paint_info, paint_info);
+}
+
+GimpPaintInfo *
+gimp_paint_info_get_standard (Gimp *gimp)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  return gimp->standard_paint_info;
+}
diff --git a/app/core/gimppaintinfo.h b/app/core/gimppaintinfo.h
new file mode 100644
index 0000000..c67b326
--- /dev/null
+++ b/app/core/gimppaintinfo.h
@@ -0,0 +1,69 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_PAINT_INFO_H__
+#define __GIMP_PAINT_INFO_H__
+
+
+#include "gimpviewable.h"
+
+
+#define GIMP_TYPE_PAINT_INFO            (gimp_paint_info_get_type ())
+#define GIMP_PAINT_INFO(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_PAINT_INFO, GimpPaintInfo))
+#define GIMP_PAINT_INFO_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_PAINT_INFO, GimpPaintInfoClass))
+#define GIMP_IS_PAINT_INFO(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_PAINT_INFO))
+#define GIMP_IS_PAINT_INFO_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_PAINT_INFO))
+#define GIMP_PAINT_INFO_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_PAINT_INFO, GimpPaintInfoClass))
+
+
+typedef struct _GimpPaintInfoClass GimpPaintInfoClass;
+
+struct _GimpPaintInfo
+{
+  GimpViewable      parent_instance;
+
+  Gimp             *gimp;
+
+  GType             paint_type;
+  GType             paint_options_type;
+
+  gchar            *blurb;
+
+  GimpPaintOptions *paint_options;
+};
+
+struct _GimpPaintInfoClass
+{
+  GimpViewableClass  parent_class;
+};
+
+
+GType           gimp_paint_info_get_type     (void) G_GNUC_CONST;
+
+GimpPaintInfo * gimp_paint_info_new          (Gimp          *gimp,
+                                              GType          paint_type,
+                                              GType          paint_options_type,
+                                              const gchar   *identifier,
+                                              const gchar   *blurb,
+                                              const gchar   *icon_name);
+
+void            gimp_paint_info_set_standard (Gimp          *gimp,
+                                              GimpPaintInfo *paint_info);
+GimpPaintInfo * gimp_paint_info_get_standard (Gimp          *gimp);
+
+
+#endif  /*  __GIMP_PAINT_INFO_H__  */
diff --git a/app/core/gimppalette-import.c b/app/core/gimppalette-import.c
new file mode 100644
index 0000000..aaa44ea
--- /dev/null
+++ b/app/core/gimppalette-import.c
@@ -0,0 +1,566 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <cairo.h>
+#include <gegl.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpcolor/gimpcolor.h"
+
+#include "core-types.h"
+
+#include "gimpchannel.h"
+#include "gimpcontainer.h"
+#include "gimpcontext.h"
+#include "gimpgradient.h"
+#include "gimpimage.h"
+#include "gimpimage-colormap.h"
+#include "gimppalette.h"
+#include "gimppalette-import.h"
+#include "gimppalette-load.h"
+#include "gimppickable.h"
+
+#include "gimp-intl.h"
+
+
+#define MAX_IMAGE_COLORS (10000 * 2)
+
+
+/*  create a palette from a gradient  ****************************************/
+
+GimpPalette *
+gimp_palette_import_from_gradient (GimpGradient                *gradient,
+                                   GimpContext                 *context,
+                                   gboolean                     reverse,
+                                   GimpGradientBlendColorSpace  blend_color_space,
+                                   const gchar                 *palette_name,
+                                   gint                         n_colors)
+{
+  GimpPalette         *palette;
+  GimpGradientSegment *seg = NULL;
+  gdouble              dx, cur_x;
+  GimpRGB              color;
+  gint                 i;
+
+  g_return_val_if_fail (GIMP_IS_GRADIENT (gradient), NULL);
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+  g_return_val_if_fail (palette_name != NULL, NULL);
+  g_return_val_if_fail (n_colors > 1, NULL);
+
+  palette = GIMP_PALETTE (gimp_palette_new (context, palette_name));
+
+  dx = 1.0 / (n_colors - 1);
+
+  for (i = 0, cur_x = 0; i < n_colors; i++, cur_x += dx)
+    {
+      seg = gimp_gradient_get_color_at (gradient, context,
+                                        seg, cur_x, reverse, blend_color_space,
+                                        &color);
+      gimp_palette_add_entry (palette, -1, NULL, &color);
+    }
+
+  return palette;
+}
+
+
+/*  create a palette from a non-indexed image  *******************************/
+
+typedef struct _ImgColors ImgColors;
+
+struct _ImgColors
+{
+  guint  count;
+  guint  r_adj;
+  guint  g_adj;
+  guint  b_adj;
+  guchar r;
+  guchar g;
+  guchar b;
+};
+
+static gint count_color_entries = 0;
+
+static GHashTable *
+gimp_palette_import_store_colors (GHashTable *table,
+                                  guchar     *colors,
+                                  guchar     *colors_real,
+                                  gint        n_colors)
+{
+  gpointer   found_color = NULL;
+  ImgColors *new_color;
+  guint      key_colors = colors[0] * 256 * 256 + colors[1] * 256 + colors[2];
+
+  if (table == NULL)
+    {
+      table = g_hash_table_new (g_direct_hash, g_direct_equal);
+      count_color_entries = 0;
+    }
+  else
+    {
+      found_color = g_hash_table_lookup (table, GUINT_TO_POINTER (key_colors));
+    }
+
+  if (found_color == NULL)
+    {
+      if (count_color_entries > MAX_IMAGE_COLORS)
+        {
+          /* Don't add any more new ones */
+          return table;
+        }
+
+      count_color_entries++;
+
+      new_color = g_slice_new (ImgColors);
+
+      new_color->count = 1;
+      new_color->r_adj = 0;
+      new_color->g_adj = 0;
+      new_color->b_adj = 0;
+      new_color->r     = colors[0];
+      new_color->g     = colors[1];
+      new_color->b     = colors[2];
+
+      g_hash_table_insert (table, GUINT_TO_POINTER (key_colors), new_color);
+    }
+  else
+    {
+      new_color = found_color;
+
+      if (new_color->count < (G_MAXINT - 1))
+        new_color->count++;
+
+      /* Now do the adjustments ...*/
+      new_color->r_adj += (colors_real[0] - colors[0]);
+      new_color->g_adj += (colors_real[1] - colors[1]);
+      new_color->b_adj += (colors_real[2] - colors[2]);
+
+      /* Boundary conditions */
+      if(new_color->r_adj > (G_MAXINT - 255))
+        new_color->r_adj /= new_color->count;
+
+      if(new_color->g_adj > (G_MAXINT - 255))
+        new_color->g_adj /= new_color->count;
+
+      if(new_color->b_adj > (G_MAXINT - 255))
+        new_color->b_adj /= new_color->count;
+    }
+
+  return table;
+}
+
+static void
+gimp_palette_import_create_list (gpointer key,
+                                 gpointer value,
+                                 gpointer user_data)
+{
+  GSList    **list      = user_data;
+  ImgColors  *color_tab = value;
+
+  *list = g_slist_prepend (*list, color_tab);
+}
+
+static gint
+gimp_palette_import_sort_colors (gconstpointer a,
+                                 gconstpointer b)
+{
+  const ImgColors *s1 = a;
+  const ImgColors *s2 = b;
+
+  if(s1->count > s2->count)
+    return -1;
+  if(s1->count < s2->count)
+    return 1;
+
+  return 0;
+}
+
+static void
+gimp_palette_import_create_image_palette (gpointer data,
+                                          gpointer user_data)
+{
+  GimpPalette *palette   = user_data;
+  ImgColors   *color_tab = data;
+  gint         n_colors;
+  gchar       *lab;
+  GimpRGB      color;
+
+  n_colors = GPOINTER_TO_INT (g_object_get_data (G_OBJECT (palette),
+                                                 "import-n-colors"));
+
+  if (gimp_palette_get_n_colors (palette) >= n_colors)
+    return;
+
+  /* TRANSLATORS: the "%s" is an item title and "%u" is the number of
+     occurrences for this item. */
+  lab = g_strdup_printf (_("%s (occurs %u)"),
+                         _("Untitled"),
+                         color_tab->count);
+
+  /* Adjust the colors to the mean of the the sample */
+  gimp_rgba_set_uchar
+    (&color,
+     (guchar) color_tab->r + (color_tab->r_adj / color_tab->count),
+     (guchar) color_tab->g + (color_tab->g_adj / color_tab->count),
+     (guchar) color_tab->b + (color_tab->b_adj / color_tab->count),
+     255);
+
+  gimp_palette_add_entry (palette, -1, lab, &color);
+
+  g_free (lab);
+}
+
+static GimpPalette *
+gimp_palette_import_make_palette (GHashTable  *table,
+                                  const gchar *palette_name,
+                                  GimpContext *context,
+                                  gint         n_colors)
+{
+  GimpPalette *palette;
+  GSList      *list = NULL;
+  GSList      *iter;
+
+  palette = GIMP_PALETTE (gimp_palette_new (context, palette_name));
+
+  if (! table)
+    return palette;
+
+  g_hash_table_foreach (table, gimp_palette_import_create_list, &list);
+  list = g_slist_sort (list, gimp_palette_import_sort_colors);
+
+  g_object_set_data (G_OBJECT (palette), "import-n-colors",
+                     GINT_TO_POINTER (n_colors));
+
+  g_slist_foreach (list, gimp_palette_import_create_image_palette, palette);
+
+  g_object_set_data (G_OBJECT (palette), "import-n-colors", NULL);
+
+  /*  Free up used memory
+   *  Note the same structure is on both the hash list and the sorted
+   *  list. So only delete it once.
+   */
+  g_hash_table_destroy (table);
+
+  for (iter = list; iter; iter = iter->next)
+    g_slice_free (ImgColors, iter->data);
+
+  g_slist_free (list);
+
+  return palette;
+}
+
+static GHashTable *
+gimp_palette_import_extract (GimpImage     *image,
+                             GimpPickable  *pickable,
+                             gint           pickable_off_x,
+                             gint           pickable_off_y,
+                             gboolean       selection_only,
+                             gint           x,
+                             gint           y,
+                             gint           width,
+                             gint           height,
+                             gint           n_colors,
+                             gint           threshold)
+{
+  GeglBuffer         *buffer;
+  GeglBufferIterator *iter;
+  GeglRectangle      *mask_roi = NULL;
+  GeglRectangle       rect     = { x, y, width, height };
+  GHashTable         *colors   = NULL;
+  const Babl         *format;
+  gint                bpp;
+  gint                mask_bpp = 0;
+
+  buffer = gimp_pickable_get_buffer (pickable);
+  format = babl_format ("R'G'B'A u8");
+
+  iter = gegl_buffer_iterator_new (buffer, &rect, 0, format,
+                                   GEGL_ACCESS_READ, GEGL_ABYSS_NONE, 2);
+  bpp = babl_format_get_bytes_per_pixel (format);
+
+  if (selection_only &&
+      ! gimp_channel_is_empty (gimp_image_get_mask (image)))
+    {
+      GimpDrawable *mask = GIMP_DRAWABLE (gimp_image_get_mask (image));
+
+      rect.x = x + pickable_off_x;
+      rect.y = y + pickable_off_y;
+
+      buffer = gimp_drawable_get_buffer (mask);
+      format = babl_format ("Y u8");
+
+      gegl_buffer_iterator_add (iter, buffer, &rect, 0, format,
+                                GEGL_ACCESS_READ, GEGL_ABYSS_NONE);
+      mask_roi = &iter->items[1].roi;
+      mask_bpp = babl_format_get_bytes_per_pixel (format);
+    }
+
+  while (gegl_buffer_iterator_next (iter))
+    {
+      const guchar *data      = iter->items[0].data;
+      const guchar *mask_data = NULL;
+      gint          length    = iter->length;
+
+      if (mask_roi)
+        mask_data = iter->items[1].data;
+
+      while (length--)
+        {
+          /*  ignore unselected, and completely transparent pixels  */
+          if ((! mask_data || *mask_data) && data[ALPHA])
+            {
+              guchar rgba[MAX_CHANNELS]     = { 0, };
+              guchar rgb_real[MAX_CHANNELS] = { 0, };
+
+              memcpy (rgba, data, 4);
+              memcpy (rgb_real, rgba, 4);
+
+              rgba[0] = (rgba[0] / threshold) * threshold;
+              rgba[1] = (rgba[1] / threshold) * threshold;
+              rgba[2] = (rgba[2] / threshold) * threshold;
+
+              colors = gimp_palette_import_store_colors (colors,
+                                                         rgba, rgb_real,
+                                                         n_colors);
+            }
+
+          data += bpp;
+
+          if (mask_data)
+            mask_data += mask_bpp;
+        }
+    }
+
+  return colors;
+}
+
+GimpPalette *
+gimp_palette_import_from_image (GimpImage   *image,
+                                GimpContext *context,
+                                const gchar *palette_name,
+                                gint         n_colors,
+                                gint         threshold,
+                                gboolean     selection_only)
+{
+  GHashTable *colors;
+  gint        x, y;
+  gint        width, height;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+  g_return_val_if_fail (palette_name != NULL, NULL);
+  g_return_val_if_fail (n_colors > 1, NULL);
+  g_return_val_if_fail (threshold > 0, NULL);
+
+  gimp_pickable_flush (GIMP_PICKABLE (image));
+
+  if (selection_only)
+    {
+      gimp_item_bounds (GIMP_ITEM (gimp_image_get_mask (image)),
+                        &x, &y, &width, &height);
+    }
+  else
+    {
+      x      = 0;
+      y      = 0;
+      width  = gimp_image_get_width  (image);
+      height = gimp_image_get_height (image);
+    }
+
+  colors = gimp_palette_import_extract (image,
+                                        GIMP_PICKABLE (image),
+                                        0, 0,
+                                        selection_only,
+                                        x, y, width, height,
+                                        n_colors, threshold);
+
+  return gimp_palette_import_make_palette (colors, palette_name, context,
+                                           n_colors);
+}
+
+
+/*  create a palette from an indexed image  **********************************/
+
+GimpPalette *
+gimp_palette_import_from_indexed_image (GimpImage   *image,
+                                        GimpContext *context,
+                                        const gchar *palette_name)
+{
+  GimpPalette  *palette;
+  const guchar *colormap;
+  guint         n_colors;
+  gint          count;
+  GimpRGB       color;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+  g_return_val_if_fail (gimp_image_get_base_type (image) == GIMP_INDEXED, NULL);
+  g_return_val_if_fail (palette_name != NULL, NULL);
+
+  palette = GIMP_PALETTE (gimp_palette_new (context, palette_name));
+
+  colormap = gimp_image_get_colormap (image);
+  n_colors = gimp_image_get_colormap_size (image);
+
+  for (count = 0; count < n_colors; ++count)
+    {
+      gchar name[256];
+
+      g_snprintf (name, sizeof (name), _("Index %d"), count);
+
+      gimp_rgba_set_uchar (&color,
+                           colormap[count * 3 + 0],
+                           colormap[count * 3 + 1],
+                           colormap[count * 3 + 2],
+                           255);
+
+      gimp_palette_add_entry (palette, -1, name, &color);
+    }
+
+  return palette;
+}
+
+
+/*  create a palette from a drawable  ****************************************/
+
+GimpPalette *
+gimp_palette_import_from_drawable (GimpDrawable *drawable,
+                                   GimpContext  *context,
+                                   const gchar  *palette_name,
+                                   gint          n_colors,
+                                   gint          threshold,
+                                   gboolean      selection_only)
+{
+  GHashTable *colors = NULL;
+  gint        x, y;
+  gint        width, height;
+  gint        off_x, off_y;
+
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (drawable)), NULL);
+  g_return_val_if_fail (palette_name != NULL, NULL);
+  g_return_val_if_fail (n_colors > 1, NULL);
+  g_return_val_if_fail (threshold > 0, NULL);
+
+  if (selection_only)
+    {
+      if (! gimp_item_mask_intersect (GIMP_ITEM (drawable),
+                                      &x, &y, &width, &height))
+        return NULL;
+    }
+  else
+    {
+      x      = 0;
+      y      = 0;
+      width  = gimp_item_get_width  (GIMP_ITEM (drawable));
+      height = gimp_item_get_height (GIMP_ITEM (drawable));
+    }
+
+  gimp_item_get_offset (GIMP_ITEM (drawable), &off_x, &off_y);
+
+  colors =
+    gimp_palette_import_extract (gimp_item_get_image (GIMP_ITEM (drawable)),
+                                 GIMP_PICKABLE (drawable),
+                                 off_x, off_y,
+                                 selection_only,
+                                 x, y, width, height,
+                                 n_colors, threshold);
+
+  return gimp_palette_import_make_palette (colors, palette_name, context,
+                                           n_colors);
+}
+
+
+/*  create a palette from a file  **********************************/
+
+GimpPalette *
+gimp_palette_import_from_file (GimpContext  *context,
+                               GFile        *file,
+                               const gchar  *palette_name,
+                               GError      **error)
+{
+  GList        *palette_list = NULL;
+  GInputStream *input;
+  GError       *my_error = NULL;
+
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+  g_return_val_if_fail (G_IS_FILE (file), NULL);
+  g_return_val_if_fail (palette_name != NULL, NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, NULL);
+
+  input = G_INPUT_STREAM (g_file_read (file, NULL, &my_error));
+  if (! input)
+    {
+      g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_OPEN,
+                   _("Could not open '%s' for reading: %s"),
+                   gimp_file_get_utf8_name (file), my_error->message);
+      g_clear_error (&my_error);
+      return NULL;
+    }
+
+  switch (gimp_palette_load_detect_format (file, input))
+    {
+    case GIMP_PALETTE_FILE_FORMAT_GPL:
+      palette_list = gimp_palette_load (context, file, input, error);
+      break;
+
+    case GIMP_PALETTE_FILE_FORMAT_ACT:
+      palette_list = gimp_palette_load_act (context, file, input, error);
+      break;
+
+    case GIMP_PALETTE_FILE_FORMAT_RIFF_PAL:
+      palette_list = gimp_palette_load_riff (context, file, input, error);
+      break;
+
+    case GIMP_PALETTE_FILE_FORMAT_PSP_PAL:
+      palette_list = gimp_palette_load_psp (context, file, input, error);
+      break;
+
+    case GIMP_PALETTE_FILE_FORMAT_ACO:
+      palette_list = gimp_palette_load_aco (context, file, input, error);
+      break;
+
+    case GIMP_PALETTE_FILE_FORMAT_CSS:
+      palette_list = gimp_palette_load_css (context, file, input, error);
+      break;
+
+    default:
+      g_set_error (error,
+                   GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                   _("Unknown type of palette file: %s"),
+                   gimp_file_get_utf8_name (file));
+      break;
+    }
+
+  g_object_unref (input);
+
+  if (palette_list)
+    {
+      GimpPalette *palette = g_object_ref (palette_list->data);
+
+      gimp_object_set_name (GIMP_OBJECT (palette), palette_name);
+
+      g_list_free_full (palette_list, (GDestroyNotify) g_object_unref);
+
+      return palette;
+    }
+
+  return NULL;
+}
diff --git a/app/core/gimppalette-import.h b/app/core/gimppalette-import.h
new file mode 100644
index 0000000..9cd3901
--- /dev/null
+++ b/app/core/gimppalette-import.h
@@ -0,0 +1,48 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_PALETTE_IMPORT__
+#define __GIMP_PALETTE_IMPORT__
+
+
+GimpPalette * gimp_palette_import_from_gradient      (GimpGradient *gradient,
+                                                      GimpContext  *context,
+                                                      gboolean      reverse,
+                                                      GimpGradientBlendColorSpace  blend_color_space,
+                                                      const gchar  *palette_name,
+                                                      gint          n_colors);
+GimpPalette * gimp_palette_import_from_image         (GimpImage    *image,
+                                                      GimpContext  *context,
+                                                      const gchar  *palette_name,
+                                                      gint          n_colors,
+                                                      gint          threshold,
+                                                      gboolean      selection_only);
+GimpPalette * gimp_palette_import_from_indexed_image (GimpImage    *image,
+                                                      GimpContext  *context,
+                                                      const gchar  *palette_name);
+GimpPalette * gimp_palette_import_from_drawable      (GimpDrawable *drawable,
+                                                      GimpContext  *context,
+                                                      const gchar  *palette_name,
+                                                      gint          n_colors,
+                                                      gint          threshold,
+                                                      gboolean      selection_only);
+GimpPalette * gimp_palette_import_from_file          (GimpContext  *context,
+                                                      GFile        *file,
+                                                      const gchar  *palette_name,
+                                                      GError      **error);
+
+#endif  /* __GIMP_PALETTE_IMPORT_H__ */
diff --git a/app/core/gimppalette-load.c b/app/core/gimppalette-load.c
new file mode 100644
index 0000000..32a1fc1
--- /dev/null
+++ b/app/core/gimppalette-load.c
@@ -0,0 +1,702 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <stdlib.h>
+
+#include <cairo.h>
+#include <gegl.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpcolor/gimpcolor.h"
+
+#include "core-types.h"
+
+#include "gimp-utils.h"
+#include "gimppalette.h"
+#include "gimppalette-load.h"
+
+#include "gimp-intl.h"
+
+
+GList *
+gimp_palette_load (GimpContext   *context,
+                   GFile         *file,
+                   GInputStream  *input,
+                   GError       **error)
+{
+  GimpPalette      *palette = NULL;
+  GimpPaletteEntry *entry;
+  GDataInputStream *data_input;
+  gchar            *str;
+  gsize             str_len;
+  gchar            *tok;
+  gint              r, g, b;
+  gint              linenum;
+
+  g_return_val_if_fail (G_IS_FILE (file), NULL);
+  g_return_val_if_fail (G_IS_INPUT_STREAM (input), NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, NULL);
+
+  data_input = g_data_input_stream_new (input);
+
+  r = g = b = 0;
+
+  linenum = 1;
+  str_len = 1024;
+  str = gimp_data_input_stream_read_line_always (data_input, &str_len,
+                                                 NULL, error);
+  if (! str)
+    goto failed;
+
+  if (! g_str_has_prefix (str, "GIMP Palette"))
+    {
+      g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                   _("Missing magic header."));
+      g_free (str);
+      goto failed;
+    }
+
+  g_free (str);
+
+  palette = g_object_new (GIMP_TYPE_PALETTE,
+                          "mime-type", "application/x-gimp-palette",
+                          NULL);
+
+  linenum++;
+  str_len = 1024;
+  str = gimp_data_input_stream_read_line_always (data_input, &str_len,
+                                                 NULL, error);
+  if (! str)
+    goto failed;
+
+  if (g_str_has_prefix (str, "Name: "))
+    {
+      gchar *utf8;
+
+      utf8 = gimp_any_to_utf8 (g_strstrip (str + strlen ("Name: ")), -1,
+                               _("Invalid UTF-8 string in palette file '%s'"),
+                               gimp_file_get_utf8_name (file));
+      gimp_object_take_name (GIMP_OBJECT (palette), utf8);
+      g_free (str);
+
+      linenum++;
+      str_len = 1024;
+      str = gimp_data_input_stream_read_line_always (data_input, &str_len,
+                                                     NULL, error);
+      if (! str)
+        goto failed;
+
+      if (g_str_has_prefix (str, "Columns: "))
+        {
+          gint columns;
+
+          if (! gimp_ascii_strtoi (g_strstrip (str + strlen ("Columns: ")),
+                                   NULL, 10, &columns))
+            {
+              g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                           _("Invalid column count."));
+              g_free (str);
+              goto failed;
+            }
+
+          if (columns < 0 || columns > 256)
+            {
+              g_message (_("Reading palette file '%s': "
+                           "Invalid number of columns in line %d. "
+                           "Using default value."),
+                         gimp_file_get_utf8_name (file), linenum);
+              columns = 0;
+            }
+
+          gimp_palette_set_columns (palette, columns);
+          g_free (str);
+
+          linenum++;
+          str_len = 1024;
+          str = gimp_data_input_stream_read_line_always (data_input, &str_len,
+                                                         NULL, error);
+          if (! str)
+            goto failed;
+        }
+    }
+  else /* old palette format */
+    {
+      gimp_object_take_name (GIMP_OBJECT (palette),
+                             g_path_get_basename (gimp_file_get_utf8_name (file)));
+    }
+
+  while (str)
+    {
+      GError *my_error = NULL;
+
+      if (str[0] != '#' && str[0] != '\0')
+        {
+          tok = strtok (str, " \t");
+          if (tok)
+            r = atoi (tok);
+          else
+            g_message (_("Reading palette file '%s': "
+                         "Missing RED component in line %d."),
+                       gimp_file_get_utf8_name (file), linenum);
+
+          tok = strtok (NULL, " \t");
+          if (tok)
+            g = atoi (tok);
+          else
+            g_message (_("Reading palette file '%s': "
+                         "Missing GREEN component in line %d."),
+                       gimp_file_get_utf8_name (file), linenum);
+
+          tok = strtok (NULL, " \t");
+          if (tok)
+            b = atoi (tok);
+          else
+            g_message (_("Reading palette file '%s': "
+                         "Missing BLUE component in line %d."),
+                       gimp_file_get_utf8_name (file), linenum);
+
+          /* optional name */
+          tok = strtok (NULL, "\n");
+
+          if (r < 0 || r > 255 ||
+              g < 0 || g > 255 ||
+              b < 0 || b > 255)
+            g_message (_("Reading palette file '%s': "
+                         "RGB value out of range in line %d."),
+                       gimp_file_get_utf8_name (file), linenum);
+
+          /* don't call gimp_palette_add_entry here, it's rather inefficient */
+          entry = g_slice_new0 (GimpPaletteEntry);
+
+          gimp_rgba_set_uchar (&entry->color,
+                               (guchar) r,
+                               (guchar) g,
+                               (guchar) b,
+                               255);
+
+          entry->name     = g_strdup (tok ? tok : _("Untitled"));
+          entry->position = gimp_palette_get_n_colors (palette);
+
+          palette->colors = g_list_prepend (palette->colors, entry);
+          palette->n_colors++;
+        }
+
+      g_free (str);
+
+      linenum++;
+      str_len = 1024;
+      str = g_data_input_stream_read_line (data_input, &str_len,
+                                           NULL, &my_error);
+      if (! str && my_error)
+        {
+          g_message (_("Reading palette file '%s': "
+                       "Read %d colors from truncated file: %s"),
+                     gimp_file_get_utf8_name (file),
+                     g_list_length (palette->colors),
+                     my_error->message);
+          g_clear_error (&my_error);
+        }
+    }
+
+  palette->colors = g_list_reverse (palette->colors);
+
+  g_object_unref (data_input);
+
+  return g_list_prepend (NULL, palette);
+
+ failed:
+
+  g_object_unref (data_input);
+
+  if (palette)
+    g_object_unref (palette);
+
+  g_prefix_error (error, _("In line %d of palette file: "), linenum);
+
+  return NULL;
+}
+
+GList *
+gimp_palette_load_act (GimpContext   *context,
+                       GFile         *file,
+                       GInputStream  *input,
+                       GError       **error)
+{
+  GimpPalette *palette;
+  gchar       *palette_name;
+  guchar       color_bytes[3];
+  gsize        bytes_read;
+
+  g_return_val_if_fail (G_IS_FILE (file), NULL);
+  g_return_val_if_fail (G_IS_INPUT_STREAM (input), NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, NULL);
+
+  palette_name = g_path_get_basename (gimp_file_get_utf8_name (file));
+  palette = GIMP_PALETTE (gimp_palette_new (context, palette_name));
+  g_free (palette_name);
+
+  while (g_input_stream_read_all (input, color_bytes, sizeof (color_bytes),
+                                  &bytes_read, NULL, NULL) &&
+         bytes_read == sizeof (color_bytes))
+    {
+      GimpRGB color;
+
+      gimp_rgba_set_uchar (&color,
+                           color_bytes[0],
+                           color_bytes[1],
+                           color_bytes[2],
+                           255);
+      gimp_palette_add_entry (palette, -1, NULL, &color);
+    }
+
+  return g_list_prepend (NULL, palette);
+}
+
+GList *
+gimp_palette_load_riff (GimpContext   *context,
+                        GFile         *file,
+                        GInputStream  *input,
+                        GError       **error)
+{
+  GimpPalette *palette;
+  gchar       *palette_name;
+  guchar       color_bytes[4];
+  gsize        bytes_read;
+
+  g_return_val_if_fail (G_IS_FILE (file), NULL);
+  g_return_val_if_fail (G_IS_INPUT_STREAM (input), NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, NULL);
+
+  palette_name = g_path_get_basename (gimp_file_get_utf8_name (file));
+  palette = GIMP_PALETTE (gimp_palette_new (context, palette_name));
+  g_free (palette_name);
+
+  if (! g_seekable_seek (G_SEEKABLE (input), 28, G_SEEK_SET, NULL, error))
+    {
+      g_object_unref (palette);
+      return NULL;
+    }
+
+  while (g_input_stream_read_all (input, color_bytes, sizeof (color_bytes),
+                                  &bytes_read, NULL, NULL) &&
+         bytes_read == sizeof (color_bytes))
+    {
+      GimpRGB color;
+
+      gimp_rgba_set_uchar (&color,
+                           color_bytes[0],
+                           color_bytes[1],
+                           color_bytes[2],
+                           255);
+      gimp_palette_add_entry (palette, -1, NULL, &color);
+    }
+
+  return g_list_prepend (NULL, palette);
+}
+
+GList *
+gimp_palette_load_psp (GimpContext   *context,
+                       GFile         *file,
+                       GInputStream  *input,
+                       GError       **error)
+{
+  GimpPalette *palette;
+  gchar       *palette_name;
+  guchar       color_bytes[4];
+  gint         number_of_colors;
+  gsize        bytes_read;
+  gint         i, j;
+  gboolean     color_ok;
+  gchar        buffer[4096];
+  /*Maximum valid file size: 256 * 4 * 3 + 256 * 2  ~= 3650 bytes */
+  gchar      **lines;
+  gchar      **ascii_colors;
+
+  g_return_val_if_fail (G_IS_FILE (file), NULL);
+  g_return_val_if_fail (G_IS_INPUT_STREAM (input), NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, NULL);
+
+  palette_name = g_path_get_basename (gimp_file_get_utf8_name (file));
+  palette = GIMP_PALETTE (gimp_palette_new (context, palette_name));
+  g_free (palette_name);
+
+  if (! g_seekable_seek (G_SEEKABLE (input), 16, G_SEEK_SET, NULL, error))
+    {
+      g_object_unref (palette);
+      return NULL;
+    }
+
+  if (! g_input_stream_read_all (input, buffer, sizeof (buffer) - 1,
+                                 &bytes_read, NULL, error))
+    {
+      g_object_unref (palette);
+      return NULL;
+    }
+
+  buffer[bytes_read] = '\0';
+
+  lines = g_strsplit (buffer, "\x0d\x0a", -1);
+
+  number_of_colors = atoi (lines[0]);
+
+  for (i = 0; i < number_of_colors; i++)
+    {
+      if (lines[i + 1] == NULL)
+        {
+          g_printerr ("Premature end of file reading %s.",
+                      gimp_file_get_utf8_name (file));
+          break;
+        }
+
+      ascii_colors = g_strsplit (lines[i + 1], " ", 3);
+      color_ok = TRUE;
+
+      for (j = 0 ; j < 3; j++)
+        {
+          if (ascii_colors[j] == NULL)
+            {
+              g_printerr ("Corrupted palette file %s.",
+                          gimp_file_get_utf8_name (file));
+              color_ok = FALSE;
+              break;
+            }
+
+          color_bytes[j] = atoi (ascii_colors[j]);
+        }
+
+      if (color_ok)
+        {
+          GimpRGB color;
+
+          gimp_rgba_set_uchar (&color,
+                               color_bytes[0],
+                               color_bytes[1],
+                               color_bytes[2],
+                               255);
+          gimp_palette_add_entry (palette, -1, NULL, &color);
+        }
+
+      g_strfreev (ascii_colors);
+    }
+
+  g_strfreev (lines);
+
+  return g_list_prepend (NULL, palette);
+}
+
+GList *
+gimp_palette_load_aco (GimpContext   *context,
+                       GFile         *file,
+                       GInputStream  *input,
+                       GError       **error)
+{
+  GimpPalette *palette;
+  gchar       *palette_name;
+  gint         format_version;
+  gint         number_of_colors;
+  gint         i;
+  gchar        header[4];
+  gsize        bytes_read;
+
+  g_return_val_if_fail (G_IS_FILE (file), NULL);
+  g_return_val_if_fail (G_IS_INPUT_STREAM (input), NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, NULL);
+
+  if (! g_input_stream_read_all (input, header, sizeof (header),
+                                 &bytes_read, NULL, error) ||
+      bytes_read != sizeof (header))
+    {
+      g_prefix_error (error,
+                      _("Could not read header from palette file '%s': "),
+                      gimp_file_get_utf8_name (file));
+      return NULL;
+    }
+
+  palette_name = g_path_get_basename (gimp_file_get_utf8_name (file));
+  palette = GIMP_PALETTE (gimp_palette_new (context, palette_name));
+  g_free (palette_name);
+
+  format_version   = header[1] + (header[0] << 8);
+  number_of_colors = header[3] + (header[2] << 8);
+
+  for (i = 0; i < number_of_colors; i++)
+    {
+      gchar     color_info[10];
+      gint      color_space;
+      gint      w, x, y, z;
+      gboolean  color_ok = FALSE;
+      GimpRGB   color;
+      GError   *my_error = NULL;
+
+      if (! g_input_stream_read_all (input, color_info, sizeof (color_info),
+                                     &bytes_read, NULL, &my_error) ||
+          bytes_read != sizeof (color_info))
+        {
+          if (palette->colors)
+            {
+              g_message (_("Reading palette file '%s': "
+                           "Read %d colors from truncated file: %s"),
+                         gimp_file_get_utf8_name (file),
+                         g_list_length (palette->colors),
+                         my_error ?
+                         my_error->message : _("Premature end of file."));
+              g_clear_error (&my_error);
+              break;
+            }
+
+          g_propagate_error (error, my_error);
+          g_object_unref (palette);
+
+          return NULL;
+        }
+
+      color_space = color_info[1] + (color_info[0] << 8);
+
+      w = (guchar) color_info[3] + ((guchar) color_info[2] << 8);
+      x = (guchar) color_info[5] + ((guchar) color_info[4] << 8);
+      y = (guchar) color_info[7] + ((guchar) color_info[6] << 8);
+      z = (guchar) color_info[9] + ((guchar) color_info[8] << 8);
+
+      if (color_space == 0) /* RGB */
+        {
+          gdouble R = ((gdouble) w) / 65536.0;
+          gdouble G = ((gdouble) x) / 65536.0;
+          gdouble B = ((gdouble) y) / 65536.0;
+
+          gimp_rgba_set (&color, R, G, B, 1.0);
+
+          color_ok = TRUE;
+        }
+      else if (color_space == 1) /* HSV */
+        {
+          GimpHSV hsv;
+
+          gdouble H = ((gdouble) w) / 65536.0;
+          gdouble S = ((gdouble) x) / 65536.0;
+          gdouble V = ((gdouble) y) / 65536.0;
+
+          gimp_hsva_set (&hsv, H, S, V, 1.0);
+          gimp_hsv_to_rgb (&hsv, &color);
+
+          color_ok = TRUE;
+        }
+      else if (color_space == 2) /* CMYK */
+        {
+          GimpCMYK cmyk;
+
+          gdouble C = 1.0 - (((gdouble) w) / 65536.0);
+          gdouble M = 1.0 - (((gdouble) x) / 65536.0);
+          gdouble Y = 1.0 - (((gdouble) y) / 65536.0);
+          gdouble K = 1.0 - (((gdouble) z) / 65536.0);
+
+          gimp_cmyka_set (&cmyk, C, M, Y, K, 1.0);
+          gimp_cmyk_to_rgb (&cmyk, &color);
+
+          color_ok = TRUE;
+        }
+      else if (color_space == 8) /* Grayscale */
+        {
+          gdouble K = 1.0 - (((gdouble) w) / 10000.0);
+
+          gimp_rgba_set (&color, K, K, K, 1.0);
+
+          color_ok = TRUE;
+        }
+      else if (color_space == 9) /* Wide? CMYK */
+        {
+          GimpCMYK cmyk;
+
+          gdouble C = 1.0 - (((gdouble) w) / 10000.0);
+          gdouble M = 1.0 - (((gdouble) x) / 10000.0);
+          gdouble Y = 1.0 - (((gdouble) y) / 10000.0);
+          gdouble K = 1.0 - (((gdouble) z) / 10000.0);
+
+          gimp_cmyka_set (&cmyk, C, M, Y, K, 1.0);
+          gimp_cmyk_to_rgb (&cmyk, &color);
+
+          color_ok = TRUE;
+        }
+      else
+        {
+          g_printerr ("Unsupported color space (%d) in ACO file %s\n",
+                      color_space, gimp_file_get_utf8_name (file));
+        }
+
+      if (format_version == 2)
+        {
+          gchar format2_preamble[4];
+          gint  number_of_chars;
+
+          if (! g_input_stream_read_all (input,
+                                         format2_preamble,
+                                         sizeof (format2_preamble),
+                                         &bytes_read, NULL, error) ||
+              bytes_read != sizeof (format2_preamble))
+            {
+              g_object_unref (palette);
+              return NULL;
+            }
+
+          number_of_chars = format2_preamble[3] + (format2_preamble[2] << 8);
+
+          if (! g_seekable_seek (G_SEEKABLE (input), number_of_chars * 2,
+                                 G_SEEK_SET, NULL, error))
+            {
+              g_object_unref (palette);
+              return NULL;
+            }
+        }
+
+      if (color_ok)
+        gimp_palette_add_entry (palette, -1, NULL, &color);
+    }
+
+  return g_list_prepend (NULL, palette);
+}
+
+
+GList *
+gimp_palette_load_css (GimpContext   *context,
+                       GFile         *file,
+                       GInputStream  *input,
+                       GError       **error)
+{
+  GimpPalette      *palette;
+  GDataInputStream *data_input;
+  gchar            *name;
+  GRegex           *regex;
+  gchar            *buf;
+
+  g_return_val_if_fail (G_IS_FILE (file), NULL);
+  g_return_val_if_fail (G_IS_INPUT_STREAM (input), NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, NULL);
+
+  regex = g_regex_new (".*color.*:(?P<param>.*);", G_REGEX_CASELESS, 0, error);
+  if (! regex)
+    return NULL;
+
+  name = g_path_get_basename (gimp_file_get_utf8_name (file));
+  palette = GIMP_PALETTE (gimp_palette_new (context, name));
+  g_free (name);
+
+  data_input = g_data_input_stream_new (input);
+
+  do
+    {
+      gsize  buf_len = 1024;
+
+      buf = g_data_input_stream_read_line (data_input, &buf_len, NULL, NULL);
+
+      if (buf)
+        {
+          GMatchInfo *matches;
+
+          if (g_regex_match (regex, buf, 0, &matches))
+            {
+              GimpRGB  color;
+              gchar   *word = g_match_info_fetch_named (matches, "param");
+
+              if (gimp_rgb_parse_css (&color, word, -1))
+                {
+                  if (! gimp_palette_find_entry (palette, &color, NULL))
+                    {
+                      gimp_palette_add_entry (palette, -1, NULL, &color);
+                    }
+                }
+
+              g_free (word);
+            }
+          g_match_info_free (matches);
+          g_free (buf);
+        }
+    }
+  while (buf);
+
+  g_regex_unref (regex);
+  g_object_unref (data_input);
+
+  return g_list_prepend (NULL, palette);
+}
+
+GimpPaletteFileFormat
+gimp_palette_load_detect_format (GFile        *file,
+                                 GInputStream *input)
+{
+  GimpPaletteFileFormat format = GIMP_PALETTE_FILE_FORMAT_UNKNOWN;
+  gchar                 header[16];
+  gsize                 bytes_read;
+
+  if (g_input_stream_read_all (input, &header, sizeof (header),
+                               &bytes_read, NULL, NULL) &&
+      bytes_read == sizeof (header))
+    {
+      if (g_str_has_prefix (header + 0, "RIFF") &&
+          g_str_has_prefix (header + 8, "PAL data"))
+        {
+          format = GIMP_PALETTE_FILE_FORMAT_RIFF_PAL;
+        }
+      else if (g_str_has_prefix (header, "GIMP Palette"))
+        {
+          format = GIMP_PALETTE_FILE_FORMAT_GPL;
+        }
+      else if (g_str_has_prefix (header, "JASC-PAL"))
+        {
+          format = GIMP_PALETTE_FILE_FORMAT_PSP_PAL;
+        }
+    }
+
+  if (format == GIMP_PALETTE_FILE_FORMAT_UNKNOWN)
+    {
+      gchar *lower = g_ascii_strdown (gimp_file_get_utf8_name (file), -1);
+
+      if (g_str_has_suffix (lower, ".aco"))
+        {
+          format = GIMP_PALETTE_FILE_FORMAT_ACO;
+        }
+      else if (g_str_has_suffix (lower, ".css"))
+        {
+          format = GIMP_PALETTE_FILE_FORMAT_CSS;
+        }
+
+      g_free (lower);
+    }
+
+  if (format == GIMP_PALETTE_FILE_FORMAT_UNKNOWN)
+    {
+      GFileInfo *info = g_file_query_info (file,
+                                           G_FILE_ATTRIBUTE_STANDARD_SIZE,
+                                           G_FILE_QUERY_INFO_NONE,
+                                           NULL, NULL);
+
+      if (info)
+        {
+          goffset size = g_file_info_get_size (info);
+
+          if (size == 768)
+            format = GIMP_PALETTE_FILE_FORMAT_ACT;
+
+          g_object_unref (info);
+        }
+    }
+
+  g_seekable_seek (G_SEEKABLE (input), 0, G_SEEK_SET, NULL, NULL);
+
+  return format;
+}
diff --git a/app/core/gimppalette-load.h b/app/core/gimppalette-load.h
new file mode 100644
index 0000000..0dececf
--- /dev/null
+++ b/app/core/gimppalette-load.h
@@ -0,0 +1,66 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_PALETTE_LOAD_H__
+#define __GIMP_PALETTE_LOAD_H__
+
+
+#define GIMP_PALETTE_FILE_EXTENSION ".gpl"
+
+
+typedef enum
+{
+  GIMP_PALETTE_FILE_FORMAT_UNKNOWN,
+  GIMP_PALETTE_FILE_FORMAT_GPL,      /* GIMP palette                        */
+  GIMP_PALETTE_FILE_FORMAT_RIFF_PAL, /* RIFF palette                        */
+  GIMP_PALETTE_FILE_FORMAT_ACT,      /* Photoshop binary color palette      */
+  GIMP_PALETTE_FILE_FORMAT_PSP_PAL,  /* JASC's Paint Shop Pro color palette */
+  GIMP_PALETTE_FILE_FORMAT_ACO,      /* Photoshop ACO color file            */
+  GIMP_PALETTE_FILE_FORMAT_CSS       /* Cascaded Stylesheet file (CSS)      */
+} GimpPaletteFileFormat;
+
+
+GList               * gimp_palette_load               (GimpContext   *context,
+                                                       GFile         *file,
+                                                       GInputStream  *input,
+                                                       GError       **error);
+GList               * gimp_palette_load_act           (GimpContext   *context,
+                                                       GFile         *file,
+                                                       GInputStream  *input,
+                                                       GError       **error);
+GList               * gimp_palette_load_riff          (GimpContext   *context,
+                                                       GFile         *file,
+                                                       GInputStream  *input,
+                                                       GError       **error);
+GList               * gimp_palette_load_psp           (GimpContext   *context,
+                                                       GFile         *file,
+                                                       GInputStream  *input,
+                                                       GError       **error);
+GList               * gimp_palette_load_aco           (GimpContext   *context,
+                                                       GFile         *file,
+                                                       GInputStream  *input,
+                                                       GError       **error);
+GList               * gimp_palette_load_css           (GimpContext   *context,
+                                                       GFile         *file,
+                                                       GInputStream  *input,
+                                                       GError       **error);
+
+GimpPaletteFileFormat gimp_palette_load_detect_format (GFile         *file,
+                                                       GInputStream  *input);
+
+
+#endif /* __GIMP_PALETTE_H__ */
diff --git a/app/core/gimppalette-save.c b/app/core/gimppalette-save.c
new file mode 100644
index 0000000..59556bf
--- /dev/null
+++ b/app/core/gimppalette-save.c
@@ -0,0 +1,77 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <cairo.h>
+#include <gegl.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpcolor/gimpcolor.h"
+
+#include "core-types.h"
+
+#include "gimppalette.h"
+#include "gimppalette-save.h"
+
+#include "gimp-intl.h"
+
+
+gboolean
+gimp_palette_save (GimpData       *data,
+                   GOutputStream  *output,
+                   GError        **error)
+{
+  GimpPalette *palette = GIMP_PALETTE (data);
+  GString     *string;
+  GList       *list;
+
+  string = g_string_new ("GIMP Palette\n");
+
+  g_string_append_printf (string,
+                          "Name: %s\n"
+                          "Columns: %d\n"
+                          "#\n",
+                          gimp_object_get_name (palette),
+                          CLAMP (gimp_palette_get_columns (palette), 0, 256));
+
+  for (list = gimp_palette_get_colors (palette);
+       list;
+       list = g_list_next (list))
+    {
+      GimpPaletteEntry *entry = list->data;
+      guchar            r, g, b;
+
+      gimp_rgb_get_uchar (&entry->color, &r, &g, &b);
+
+      g_string_append_printf (string, "%3d %3d %3d\t%s\n",
+                              r, g, b, entry->name);
+    }
+
+  if (! g_output_stream_write_all (output, string->str, string->len,
+                                   NULL, NULL, error))
+    {
+      g_string_free (string, TRUE);
+
+      return FALSE;
+    }
+
+  g_string_free (string, TRUE);
+
+  return TRUE;
+}
diff --git a/app/core/gimppalette-save.h b/app/core/gimppalette-save.h
new file mode 100644
index 0000000..e72c448
--- /dev/null
+++ b/app/core/gimppalette-save.h
@@ -0,0 +1,28 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_PALETTE_SAVE_H__
+#define __GIMP_PALETTE_SAVE_H__
+
+
+/*  don't call this function directly, use gimp_data_save() instead  */
+gboolean   gimp_palette_save (GimpData       *data,
+                              GOutputStream  *output,
+                              GError        **error);
+
+
+#endif /* __GIMP_PALETTE_SAVE_H__ */
diff --git a/app/core/gimppalette.c b/app/core/gimppalette.c
new file mode 100644
index 0000000..f5b848c
--- /dev/null
+++ b/app/core/gimppalette.c
@@ -0,0 +1,721 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <cairo.h>
+#include <gegl.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpcolor/gimpcolor.h"
+
+#include "core-types.h"
+
+#include "gimp-memsize.h"
+#include "gimppalette.h"
+#include "gimppalette-load.h"
+#include "gimppalette-save.h"
+#include "gimptagged.h"
+#include "gimptempbuf.h"
+
+#include "gimp-intl.h"
+
+
+#define RGB_EPSILON 1e-6
+
+
+/*  local function prototypes  */
+
+static void          gimp_palette_tagged_iface_init (GimpTaggedInterface  *iface);
+
+static void          gimp_palette_finalize          (GObject              *object);
+
+static gint64        gimp_palette_get_memsize       (GimpObject           *object,
+                                                     gint64               *gui_size);
+
+static void          gimp_palette_get_preview_size  (GimpViewable         *viewable,
+                                                     gint                  size,
+                                                     gboolean              popup,
+                                                     gboolean              dot_for_dot,
+                                                     gint                 *width,
+                                                     gint                 *height);
+static gboolean      gimp_palette_get_popup_size    (GimpViewable         *viewable,
+                                                     gint                  width,
+                                                     gint                  height,
+                                                     gboolean              dot_for_dot,
+                                                     gint                 *popup_width,
+                                                     gint                 *popup_height);
+static GimpTempBuf * gimp_palette_get_new_preview   (GimpViewable         *viewable,
+                                                     GimpContext          *context,
+                                                     gint                  width,
+                                                     gint                  height);
+static gchar       * gimp_palette_get_description   (GimpViewable         *viewable,
+                                                     gchar               **tooltip);
+static const gchar * gimp_palette_get_extension     (GimpData             *data);
+static void          gimp_palette_copy              (GimpData             *data,
+                                                     GimpData             *src_data);
+
+static void          gimp_palette_entry_free        (GimpPaletteEntry     *entry);
+static gint64        gimp_palette_entry_get_memsize (GimpPaletteEntry     *entry,
+                                                     gint64               *gui_size);
+static gchar       * gimp_palette_get_checksum      (GimpTagged           *tagged);
+
+
+G_DEFINE_TYPE_WITH_CODE (GimpPalette, gimp_palette, GIMP_TYPE_DATA,
+                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_TAGGED,
+                                                gimp_palette_tagged_iface_init))
+
+#define parent_class gimp_palette_parent_class
+
+
+static void
+gimp_palette_class_init (GimpPaletteClass *klass)
+{
+  GObjectClass      *object_class      = G_OBJECT_CLASS (klass);
+  GimpObjectClass   *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+  GimpViewableClass *viewable_class    = GIMP_VIEWABLE_CLASS (klass);
+  GimpDataClass     *data_class        = GIMP_DATA_CLASS (klass);
+
+  object_class->finalize            = gimp_palette_finalize;
+
+  gimp_object_class->get_memsize    = gimp_palette_get_memsize;
+
+  viewable_class->default_icon_name = "gtk-select-color";
+  viewable_class->get_preview_size  = gimp_palette_get_preview_size;
+  viewable_class->get_popup_size    = gimp_palette_get_popup_size;
+  viewable_class->get_new_preview   = gimp_palette_get_new_preview;
+  viewable_class->get_description   = gimp_palette_get_description;
+
+  data_class->save                  = gimp_palette_save;
+  data_class->get_extension         = gimp_palette_get_extension;
+  data_class->copy                  = gimp_palette_copy;
+}
+
+static void
+gimp_palette_tagged_iface_init (GimpTaggedInterface *iface)
+{
+  iface->get_checksum = gimp_palette_get_checksum;
+}
+
+static void
+gimp_palette_init (GimpPalette *palette)
+{
+  palette->colors    = NULL;
+  palette->n_colors  = 0;
+  palette->n_columns = 0;
+}
+
+static void
+gimp_palette_finalize (GObject *object)
+{
+  GimpPalette *palette = GIMP_PALETTE (object);
+
+  if (palette->colors)
+    {
+      g_list_free_full (palette->colors,
+                        (GDestroyNotify) gimp_palette_entry_free);
+      palette->colors = NULL;
+    }
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static gint64
+gimp_palette_get_memsize (GimpObject *object,
+                          gint64     *gui_size)
+{
+  GimpPalette *palette = GIMP_PALETTE (object);
+  gint64       memsize = 0;
+
+  memsize += gimp_g_list_get_memsize_foreach (palette->colors,
+                                              (GimpMemsizeFunc)
+                                              gimp_palette_entry_get_memsize,
+                                              gui_size);
+
+  return memsize + GIMP_OBJECT_CLASS (parent_class)->get_memsize (object,
+                                                                  gui_size);
+}
+
+static void
+gimp_palette_get_preview_size (GimpViewable *viewable,
+                               gint          size,
+                               gboolean      popup,
+                               gboolean      dot_for_dot,
+                               gint         *width,
+                               gint         *height)
+{
+  *width  = size;
+  *height = 1 + size / 2;
+}
+
+static gboolean
+gimp_palette_get_popup_size (GimpViewable *viewable,
+                             gint          width,
+                             gint          height,
+                             gboolean      dot_for_dot,
+                             gint         *popup_width,
+                             gint         *popup_height)
+{
+  GimpPalette *palette = GIMP_PALETTE (viewable);
+  gint         p_width;
+  gint         p_height;
+
+  if (! palette->n_colors)
+    return FALSE;
+
+  if (palette->n_columns)
+    p_width = palette->n_columns;
+  else
+    p_width = MIN (palette->n_colors, 16);
+
+  p_height = MAX (1, palette->n_colors / p_width);
+
+  if (p_width * 4 > width || p_height * 4 > height)
+    {
+      *popup_width  = p_width  * 4;
+      *popup_height = p_height * 4;
+
+      return TRUE;
+    }
+
+  return FALSE;
+}
+
+static GimpTempBuf *
+gimp_palette_get_new_preview (GimpViewable *viewable,
+                              GimpContext  *context,
+                              gint          width,
+                              gint          height)
+{
+  GimpPalette *palette  = GIMP_PALETTE (viewable);
+  GimpTempBuf *temp_buf;
+  guchar      *buf;
+  guchar      *b;
+  GList       *list;
+  gint         columns;
+  gint         rows;
+  gint         cell_size;
+  gint         x, y;
+
+  temp_buf = gimp_temp_buf_new (width, height, babl_format ("R'G'B' u8"));
+  memset (gimp_temp_buf_get_data (temp_buf), 255, width * height * 3);
+
+  if (palette->n_columns > 1)
+    cell_size = MAX (4, width / palette->n_columns);
+  else
+    cell_size = 4;
+
+  columns = width  / cell_size;
+  rows    = height / cell_size;
+
+  buf = gimp_temp_buf_get_data (temp_buf);
+  b   = g_new (guchar, width * 3);
+
+  list = palette->colors;
+
+  for (y = 0; y < rows && list; y++)
+    {
+      gint i;
+
+      memset (b, 255, width * 3);
+
+      for (x = 0; x < columns && list; x++)
+        {
+          GimpPaletteEntry *entry = list->data;
+
+          list = g_list_next (list);
+
+          gimp_rgb_get_uchar (&entry->color,
+                              &b[x * cell_size * 3 + 0],
+                              &b[x * cell_size * 3 + 1],
+                              &b[x * cell_size * 3 + 2]);
+
+          for (i = 1; i < cell_size; i++)
+            {
+              b[(x * cell_size + i) * 3 + 0] = b[(x * cell_size) * 3 + 0];
+              b[(x * cell_size + i) * 3 + 1] = b[(x * cell_size) * 3 + 1];
+              b[(x * cell_size + i) * 3 + 2] = b[(x * cell_size) * 3 + 2];
+            }
+        }
+
+      for (i = 0; i < cell_size; i++)
+        memcpy (buf + ((y * cell_size + i) * width) * 3, b, width * 3);
+    }
+
+  g_free (b);
+
+  return temp_buf;
+}
+
+static gchar *
+gimp_palette_get_description (GimpViewable  *viewable,
+                              gchar        **tooltip)
+{
+  GimpPalette *palette = GIMP_PALETTE (viewable);
+
+  return g_strdup_printf ("%s (%d)",
+                          gimp_object_get_name (palette),
+                          palette->n_colors);
+}
+
+GimpData *
+gimp_palette_new (GimpContext *context,
+                  const gchar *name)
+{
+  g_return_val_if_fail (name != NULL, NULL);
+  g_return_val_if_fail (*name != '\0', NULL);
+
+  return g_object_new (GIMP_TYPE_PALETTE,
+                       "name", name,
+                       NULL);
+}
+
+GimpData *
+gimp_palette_get_standard (GimpContext *context)
+{
+  static GimpData *standard_palette = NULL;
+
+  if (! standard_palette)
+    {
+      standard_palette = gimp_palette_new (context, "Standard");
+
+      gimp_data_clean (standard_palette);
+      gimp_data_make_internal (standard_palette, "gimp-palette-standard");
+
+      g_object_add_weak_pointer (G_OBJECT (standard_palette),
+                                 (gpointer *) &standard_palette);
+    }
+
+  return standard_palette;
+}
+
+static const gchar *
+gimp_palette_get_extension (GimpData *data)
+{
+  return GIMP_PALETTE_FILE_EXTENSION;
+}
+
+static void
+gimp_palette_copy (GimpData *data,
+                   GimpData *src_data)
+{
+  GimpPalette *palette     = GIMP_PALETTE (data);
+  GimpPalette *src_palette = GIMP_PALETTE (src_data);
+  GList       *list;
+
+  gimp_data_freeze (data);
+
+  if (palette->colors)
+    {
+      g_list_free_full (palette->colors,
+                        (GDestroyNotify) gimp_palette_entry_free);
+      palette->colors = NULL;
+    }
+
+  palette->n_colors  = 0;
+  palette->n_columns = src_palette->n_columns;
+
+  for (list = src_palette->colors; list; list = g_list_next (list))
+    {
+      GimpPaletteEntry *entry = list->data;
+
+      gimp_palette_add_entry (palette, -1, entry->name, &entry->color);
+    }
+
+  gimp_data_thaw (data);
+}
+
+static gchar *
+gimp_palette_get_checksum (GimpTagged *tagged)
+{
+  GimpPalette *palette         = GIMP_PALETTE (tagged);
+  gchar       *checksum_string = NULL;
+
+  if (palette->n_colors > 0)
+    {
+      GChecksum *checksum       = g_checksum_new (G_CHECKSUM_MD5);
+      GList     *color_iterator = palette->colors;
+
+      g_checksum_update (checksum, (const guchar *) &palette->n_colors, sizeof (palette->n_colors));
+      g_checksum_update (checksum, (const guchar *) &palette->n_columns, sizeof (palette->n_columns));
+
+      while (color_iterator)
+        {
+          GimpPaletteEntry *entry = (GimpPaletteEntry *) color_iterator->data;
+
+          g_checksum_update (checksum, (const guchar *) &entry->color, sizeof (entry->color));
+          if (entry->name)
+            g_checksum_update (checksum, (const guchar *) entry->name, strlen (entry->name));
+
+          color_iterator = g_list_next (color_iterator);
+        }
+
+      checksum_string = g_strdup (g_checksum_get_string (checksum));
+
+      g_checksum_free (checksum);
+    }
+
+  return checksum_string;
+}
+
+
+/*  public functions  */
+
+GList *
+gimp_palette_get_colors (GimpPalette *palette)
+{
+  g_return_val_if_fail (GIMP_IS_PALETTE (palette), NULL);
+
+  return palette->colors;
+}
+
+gint
+gimp_palette_get_n_colors (GimpPalette *palette)
+{
+  g_return_val_if_fail (GIMP_IS_PALETTE (palette), 0);
+
+  return palette->n_colors;
+}
+
+void
+gimp_palette_move_entry (GimpPalette      *palette,
+                         GimpPaletteEntry *entry,
+                         gint              position)
+{
+  GList *list;
+  gint   pos = 0;
+
+  g_return_if_fail (GIMP_IS_PALETTE (palette));
+  g_return_if_fail (entry != NULL);
+
+  if (g_list_find (palette->colors, entry))
+    {
+      pos = entry->position;
+
+      if (entry->position == position)
+        return;
+
+      entry->position = position;
+      palette->colors = g_list_remove (palette->colors,
+                                       entry);
+      palette->colors = g_list_insert (palette->colors,
+                                       entry, position);
+
+      if (pos < position)
+        {
+          for (list = g_list_nth (palette->colors, pos);
+               list && pos < position;
+               list = g_list_next (list))
+            {
+              entry = (GimpPaletteEntry *) list->data;
+
+              entry->position = pos++;
+            }
+        }
+      else
+        {
+          for (list = g_list_nth (palette->colors, position + 1);
+               list && position < pos;
+               list = g_list_next (list))
+            {
+              entry = (GimpPaletteEntry *) list->data;
+
+              entry->position += 1;
+              pos--;
+            }
+        }
+
+      gimp_data_dirty (GIMP_DATA (palette));
+    }
+}
+
+GimpPaletteEntry *
+gimp_palette_add_entry (GimpPalette   *palette,
+                        gint           position,
+                        const gchar   *name,
+                        const GimpRGB *color)
+{
+  GimpPaletteEntry *entry;
+
+  g_return_val_if_fail (GIMP_IS_PALETTE (palette), NULL);
+  g_return_val_if_fail (color != NULL, NULL);
+
+  entry = g_slice_new0 (GimpPaletteEntry);
+
+  entry->color = *color;
+  entry->name  = g_strdup (name ? name : _("Untitled"));
+
+  if (position < 0 || position >= palette->n_colors)
+    {
+      entry->position = palette->n_colors;
+      palette->colors = g_list_append (palette->colors, entry);
+    }
+  else
+    {
+      GList *list;
+
+      entry->position = position;
+      palette->colors = g_list_insert (palette->colors, entry, position);
+
+      /* renumber the displaced entries */
+      for (list = g_list_nth (palette->colors, position + 1);
+           list;
+           list = g_list_next (list))
+        {
+          GimpPaletteEntry *entry2 = list->data;
+
+          entry2->position += 1;
+        }
+    }
+
+  palette->n_colors += 1;
+
+  gimp_data_dirty (GIMP_DATA (palette));
+
+  return entry;
+}
+
+void
+gimp_palette_delete_entry (GimpPalette      *palette,
+                           GimpPaletteEntry *entry)
+{
+  GList *list;
+  gint   pos = 0;
+
+  g_return_if_fail (GIMP_IS_PALETTE (palette));
+  g_return_if_fail (entry != NULL);
+
+  if (g_list_find (palette->colors, entry))
+    {
+      pos = entry->position;
+      gimp_palette_entry_free (entry);
+
+      palette->colors = g_list_remove (palette->colors, entry);
+
+      palette->n_colors--;
+
+      for (list = g_list_nth (palette->colors, pos);
+           list;
+           list = g_list_next (list))
+        {
+          entry = (GimpPaletteEntry *) list->data;
+
+          entry->position = pos++;
+        }
+
+      gimp_data_dirty (GIMP_DATA (palette));
+    }
+}
+
+gboolean
+gimp_palette_set_entry (GimpPalette   *palette,
+                        gint           position,
+                        const gchar   *name,
+                        const GimpRGB *color)
+{
+  GimpPaletteEntry *entry;
+
+  g_return_val_if_fail (GIMP_IS_PALETTE (palette), FALSE);
+  g_return_val_if_fail (color != NULL, FALSE);
+
+  entry = gimp_palette_get_entry (palette, position);
+
+  if (! entry)
+    return FALSE;
+
+  entry->color = *color;
+
+  if (entry->name)
+    g_free (entry->name);
+
+  entry->name = g_strdup (name);
+
+  gimp_data_dirty (GIMP_DATA (palette));
+
+  return TRUE;
+}
+
+gboolean
+gimp_palette_set_entry_color (GimpPalette   *palette,
+                              gint           position,
+                              const GimpRGB *color)
+{
+  GimpPaletteEntry *entry;
+
+  g_return_val_if_fail (GIMP_IS_PALETTE (palette), FALSE);
+  g_return_val_if_fail (color != NULL, FALSE);
+
+  entry = gimp_palette_get_entry (palette, position);
+
+  if (! entry)
+    return FALSE;
+
+  entry->color = *color;
+
+  gimp_data_dirty (GIMP_DATA (palette));
+
+  return TRUE;
+}
+
+gboolean
+gimp_palette_set_entry_name (GimpPalette *palette,
+                             gint         position,
+                             const gchar *name)
+{
+  GimpPaletteEntry *entry;
+
+  g_return_val_if_fail (GIMP_IS_PALETTE (palette), FALSE);
+
+  entry = gimp_palette_get_entry (palette, position);
+
+  if (! entry)
+    return FALSE;
+
+  if (entry->name)
+    g_free (entry->name);
+
+  entry->name = g_strdup (name);
+
+  gimp_data_dirty (GIMP_DATA (palette));
+
+  return TRUE;
+}
+
+GimpPaletteEntry *
+gimp_palette_get_entry (GimpPalette *palette,
+                        gint         position)
+{
+  g_return_val_if_fail (GIMP_IS_PALETTE (palette), NULL);
+
+  return g_list_nth_data (palette->colors, position);
+}
+
+void
+gimp_palette_set_columns (GimpPalette *palette,
+                          gint         columns)
+{
+  g_return_if_fail (GIMP_IS_PALETTE (palette));
+
+  columns = CLAMP (columns, 0, 64);
+
+  if (palette->n_columns != columns)
+    {
+      palette->n_columns = columns;
+
+      gimp_data_dirty (GIMP_DATA (palette));
+    }
+}
+
+gint
+gimp_palette_get_columns (GimpPalette *palette)
+{
+  g_return_val_if_fail (GIMP_IS_PALETTE (palette), 0);
+
+  return palette->n_columns;
+}
+
+GimpPaletteEntry *
+gimp_palette_find_entry (GimpPalette      *palette,
+                         const GimpRGB    *color,
+                         GimpPaletteEntry *start_from)
+{
+  GimpPaletteEntry *entry;
+
+  g_return_val_if_fail (GIMP_IS_PALETTE (palette), NULL);
+  g_return_val_if_fail (color != NULL, NULL);
+
+  if (! start_from)
+    {
+      GList *list;
+
+      /* search from the start */
+
+      for (list = palette->colors; list; list = g_list_next (list))
+        {
+          entry = (GimpPaletteEntry *) list->data;
+          if (gimp_rgb_distance (&entry->color, color) < RGB_EPSILON)
+            return entry;
+        }
+    }
+  else if (gimp_rgb_distance (&start_from->color, color) < RGB_EPSILON)
+    {
+      return start_from;
+    }
+  else
+    {
+      GList *old = g_list_find (palette->colors, start_from);
+      GList *next;
+      GList *prev;
+
+      g_return_val_if_fail (old != NULL, NULL);
+
+      next = old->next;
+      prev = old->prev;
+
+      /* proximity-based search */
+
+      while (next || prev)
+        {
+          if (next)
+            {
+              entry = (GimpPaletteEntry *) next->data;
+              if (gimp_rgb_distance (&entry->color, color) < RGB_EPSILON)
+                return entry;
+
+              next = next->next;
+            }
+
+          if (prev)
+            {
+              entry = (GimpPaletteEntry *) prev->data;
+              if (gimp_rgb_distance (&entry->color, color) < RGB_EPSILON)
+                return entry;
+
+              prev = prev->prev;
+            }
+        }
+    }
+
+  return NULL;
+}
+
+
+/*  private functions  */
+
+static void
+gimp_palette_entry_free (GimpPaletteEntry *entry)
+{
+  g_return_if_fail (entry != NULL);
+
+  g_free (entry->name);
+
+  g_slice_free (GimpPaletteEntry, entry);
+}
+
+static gint64
+gimp_palette_entry_get_memsize (GimpPaletteEntry *entry,
+                                gint64           *gui_size)
+{
+  gint64 memsize = sizeof (GimpPaletteEntry);
+
+  memsize += gimp_string_get_memsize (entry->name);
+
+  return memsize;
+}
diff --git a/app/core/gimppalette.h b/app/core/gimppalette.h
new file mode 100644
index 0000000..5bc6d8c
--- /dev/null
+++ b/app/core/gimppalette.h
@@ -0,0 +1,103 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_PALETTE_H__
+#define __GIMP_PALETTE_H__
+
+
+#include "gimpdata.h"
+
+
+#define GIMP_TYPE_PALETTE            (gimp_palette_get_type ())
+#define GIMP_PALETTE(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_PALETTE, GimpPalette))
+#define GIMP_PALETTE_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_PALETTE, GimpPaletteClass))
+#define GIMP_IS_PALETTE(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_PALETTE))
+#define GIMP_IS_PALETTE_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_PALETTE))
+#define GIMP_PALETTE_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_PALETTE, GimpPaletteClass))
+
+
+struct _GimpPaletteEntry
+{
+  GimpRGB  color;
+  gchar   *name;
+
+  /* EEK */
+  gint     position;
+};
+
+
+typedef struct _GimpPaletteClass GimpPaletteClass;
+
+struct _GimpPalette
+{
+  GimpData  parent_instance;
+
+  GList    *colors;
+  gint      n_colors;
+
+  gint      n_columns;
+};
+
+struct _GimpPaletteClass
+{
+  GimpDataClass  parent_class;
+};
+
+
+GType              gimp_palette_get_type        (void) G_GNUC_CONST;
+
+GimpData         * gimp_palette_new             (GimpContext      *context,
+                                                 const gchar      *name);
+GimpData         * gimp_palette_get_standard    (GimpContext      *context);
+
+GList            * gimp_palette_get_colors      (GimpPalette      *palette);
+gint               gimp_palette_get_n_colors    (GimpPalette      *palette);
+
+void               gimp_palette_move_entry      (GimpPalette      *palette,
+                                                 GimpPaletteEntry *entry,
+                                                 gint              position);
+
+GimpPaletteEntry * gimp_palette_add_entry       (GimpPalette      *palette,
+                                                 gint              position,
+                                                 const gchar      *name,
+                                                 const GimpRGB    *color);
+void               gimp_palette_delete_entry    (GimpPalette      *palette,
+                                                 GimpPaletteEntry *entry);
+
+gboolean           gimp_palette_set_entry       (GimpPalette      *palette,
+                                                 gint              position,
+                                                 const gchar      *name,
+                                                 const GimpRGB    *color);
+gboolean           gimp_palette_set_entry_color (GimpPalette      *palette,
+                                                 gint              position,
+                                                 const GimpRGB    *color);
+gboolean           gimp_palette_set_entry_name  (GimpPalette      *palette,
+                                                 gint              position,
+                                                 const gchar      *name);
+GimpPaletteEntry * gimp_palette_get_entry       (GimpPalette      *palette,
+                                                 gint              position);
+
+void               gimp_palette_set_columns     (GimpPalette      *palette,
+                                                 gint              columns);
+gint               gimp_palette_get_columns     (GimpPalette      *palette);
+
+GimpPaletteEntry * gimp_palette_find_entry      (GimpPalette      *palette,
+                                                 const GimpRGB    *color,
+                                                 GimpPaletteEntry *start_from);
+
+
+#endif /* __GIMP_PALETTE_H__ */
diff --git a/app/core/gimppalettemru.c b/app/core/gimppalettemru.c
new file mode 100644
index 0000000..f68c469
--- /dev/null
+++ b/app/core/gimppalettemru.c
@@ -0,0 +1,230 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimppalettemru.c
+ * Copyright (C) 2014 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <cairo.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpcolor/gimpcolor.h"
+#include "libgimpconfig/gimpconfig.h"
+
+#include "core-types.h"
+
+#include "gimppalettemru.h"
+
+#include "gimp-intl.h"
+
+
+#define MAX_N_COLORS 256
+#define RGBA_EPSILON 1e-4
+
+enum
+{
+  COLOR_HISTORY = 1
+};
+
+
+G_DEFINE_TYPE (GimpPaletteMru, gimp_palette_mru, GIMP_TYPE_PALETTE)
+
+#define parent_class gimp_palette_mru_parent_class
+
+
+static void
+gimp_palette_mru_class_init (GimpPaletteMruClass *klass)
+{
+}
+
+static void
+gimp_palette_mru_init (GimpPaletteMru *palette)
+{
+}
+
+
+/*  public functions  */
+
+GimpData *
+gimp_palette_mru_new (const gchar *name)
+{
+  GimpPaletteMru *palette;
+
+  g_return_val_if_fail (name != NULL, NULL);
+  g_return_val_if_fail (*name != '\0', NULL);
+
+  palette = g_object_new (GIMP_TYPE_PALETTE_MRU,
+                          "name",      name,
+                          "mime-type", "application/x-gimp-palette",
+                          NULL);
+
+  return GIMP_DATA (palette);
+}
+
+void
+gimp_palette_mru_load (GimpPaletteMru *mru,
+                       GFile          *file)
+{
+  GimpPalette *palette;
+  GScanner    *scanner;
+  GTokenType   token;
+
+  g_return_if_fail (GIMP_IS_PALETTE_MRU (mru));
+  g_return_if_fail (G_IS_FILE (file));
+
+  palette = GIMP_PALETTE (mru);
+
+  scanner = gimp_scanner_new_gfile (file, NULL);
+  if (! scanner)
+    return;
+
+  g_scanner_scope_add_symbol (scanner, 0, "color-history",
+                              GINT_TO_POINTER (COLOR_HISTORY));
+
+  token = G_TOKEN_LEFT_PAREN;
+
+  while (g_scanner_peek_next_token (scanner) == token)
+    {
+      token = g_scanner_get_next_token (scanner);
+
+      switch (token)
+        {
+        case G_TOKEN_LEFT_PAREN:
+          token = G_TOKEN_SYMBOL;
+          break;
+
+        case G_TOKEN_SYMBOL:
+          if (scanner->value.v_symbol == GINT_TO_POINTER (COLOR_HISTORY))
+            {
+              while (g_scanner_peek_next_token (scanner) == G_TOKEN_LEFT_PAREN)
+                {
+                  GimpRGB color;
+
+                  if (! gimp_scanner_parse_color (scanner, &color))
+                    goto end;
+
+                  gimp_palette_add_entry (palette, -1,
+                                          _("History Color"), &color);
+
+                  if (gimp_palette_get_n_colors (palette) == MAX_N_COLORS)
+                    goto end;
+                }
+            }
+          token = G_TOKEN_RIGHT_PAREN;
+          break;
+
+        case G_TOKEN_RIGHT_PAREN:
+          token = G_TOKEN_LEFT_PAREN;
+          break;
+
+        default: /* do nothing */
+          break;
+        }
+    }
+
+ end:
+  gimp_scanner_destroy (scanner);
+}
+
+void
+gimp_palette_mru_save (GimpPaletteMru *mru,
+                       GFile          *file)
+{
+  GimpPalette      *palette;
+  GimpConfigWriter *writer;
+  GList            *list;
+
+  g_return_if_fail (GIMP_IS_PALETTE_MRU (mru));
+  g_return_if_fail (G_IS_FILE (file));
+
+  writer = gimp_config_writer_new_gfile (file,
+                                         TRUE,
+                                         "GIMP colorrc\n\n"
+                                         "This file holds a list of "
+                                         "recently used colors.",
+                                         NULL);
+  if (! writer)
+    return;
+
+  palette = GIMP_PALETTE (mru);
+
+  gimp_config_writer_open (writer, "color-history");
+
+  for (list = palette->colors; list; list = g_list_next (list))
+    {
+      GimpPaletteEntry *entry = list->data;
+      gchar             buf[4][G_ASCII_DTOSTR_BUF_SIZE];
+
+      g_ascii_dtostr (buf[0], G_ASCII_DTOSTR_BUF_SIZE, entry->color.r);
+      g_ascii_dtostr (buf[1], G_ASCII_DTOSTR_BUF_SIZE, entry->color.g);
+      g_ascii_dtostr (buf[2], G_ASCII_DTOSTR_BUF_SIZE, entry->color.b);
+      g_ascii_dtostr (buf[3], G_ASCII_DTOSTR_BUF_SIZE, entry->color.a);
+
+      gimp_config_writer_open (writer, "color-rgba");
+      gimp_config_writer_printf (writer, "%s %s %s %s",
+                                 buf[0], buf[1], buf[2], buf[3]);
+      gimp_config_writer_close (writer);
+    }
+
+  gimp_config_writer_close (writer);
+
+  gimp_config_writer_finish (writer, "end of colorrc", NULL);
+}
+
+void
+gimp_palette_mru_add (GimpPaletteMru *mru,
+                      const GimpRGB  *color)
+{
+  GimpPalette *palette;
+  GList       *list;
+
+  g_return_if_fail (GIMP_IS_PALETTE_MRU (mru));
+  g_return_if_fail (color != NULL);
+
+  palette = GIMP_PALETTE (mru);
+
+  /*  is the added color already there?  */
+  for (list = gimp_palette_get_colors (palette);
+       list;
+       list = g_list_next (list))
+    {
+      GimpPaletteEntry *entry = list->data;
+
+      if (gimp_rgba_distance (&entry->color, color) < RGBA_EPSILON)
+        {
+          gimp_palette_move_entry (palette, entry, 0);
+
+          /*  Even though they are nearly the same color, let's make them
+           *  exactly equal.
+           */
+          gimp_palette_set_entry_color (palette, 0, color);
+
+          return;
+        }
+    }
+
+  if (gimp_palette_get_n_colors (palette) == MAX_N_COLORS)
+    {
+      gimp_palette_delete_entry (palette,
+                                 gimp_palette_get_entry (palette,
+                                                         MAX_N_COLORS - 1));
+    }
+
+  gimp_palette_add_entry (palette, 0, _("History Color"), color);
+}
diff --git a/app/core/gimppalettemru.h b/app/core/gimppalettemru.h
new file mode 100644
index 0000000..0525553
--- /dev/null
+++ b/app/core/gimppalettemru.h
@@ -0,0 +1,62 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimppalettemru.h
+ * Copyright (C) 2014 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_PALETTE_MRU_H__
+#define __GIMP_PALETTE_MRU_H__
+
+
+#include "gimppalette.h"
+
+
+#define GIMP_TYPE_PALETTE_MRU            (gimp_palette_mru_get_type ())
+#define GIMP_PALETTE_MRU(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_PALETTE_MRU, GimpPaletteMru))
+#define GIMP_PALETTE_MRU_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_PALETTE_MRU, GimpPaletteMruClass))
+#define GIMP_IS_PALETTE_MRU(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_PALETTE_MRU))
+#define GIMP_IS_PALETTE_MRU_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_PALETTE_MRU))
+#define GIMP_PALETTE_MRU_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_PALETTE_MRU, GimpPaletteMruClass))
+
+
+typedef struct _GimpPaletteMruClass GimpPaletteMruClass;
+
+struct _GimpPaletteMru
+{
+  GimpPalette  parent_instance;
+};
+
+struct _GimpPaletteMruClass
+{
+  GimpPaletteClass  parent_class;
+};
+
+
+GType      gimp_palette_mru_get_type (void) G_GNUC_CONST;
+
+GimpData * gimp_palette_mru_new      (const gchar    *name);
+
+void       gimp_palette_mru_load     (GimpPaletteMru *mru,
+                                      GFile          *file);
+void       gimp_palette_mru_save     (GimpPaletteMru *mru,
+                                      GFile          *file);
+
+void       gimp_palette_mru_add      (GimpPaletteMru *mru,
+                                      const GimpRGB  *color);
+
+
+#endif  /*  __GIMP_PALETTE_MRU_H__  */
diff --git a/app/core/gimpparamspecs-desc.c b/app/core/gimpparamspecs-desc.c
new file mode 100644
index 0000000..a59f14f
--- /dev/null
+++ b/app/core/gimpparamspecs-desc.c
@@ -0,0 +1,193 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <gio/gio.h>
+
+#include "libgimpbase/gimpbase.h"
+
+#include "core-types.h"
+
+#include "gimpparamspecs.h"
+#include "gimpparamspecs-desc.h"
+
+
+static inline const gchar *
+gimp_param_spec_get_blurb (GParamSpec *pspec)
+{
+  const gchar *blurb = g_param_spec_get_blurb (pspec);
+
+  return blurb ? blurb : "";
+}
+
+static gchar *
+gimp_param_spec_boolean_desc (GParamSpec *pspec)
+{
+  const gchar *blurb = gimp_param_spec_get_blurb (pspec);
+
+  return g_strconcat (blurb, " (TRUE or FALSE)", NULL);
+}
+
+static gchar *
+gimp_param_spec_int32_desc (GParamSpec *pspec)
+{
+  GParamSpecInt *ispec = G_PARAM_SPEC_INT (pspec);
+  const gchar   *blurb = gimp_param_spec_get_blurb (pspec);
+
+  if (ispec->minimum == G_MININT32 && ispec->maximum == G_MAXINT32)
+    return g_strdup (blurb);
+
+  if (ispec->minimum == G_MININT32)
+    return g_strdup_printf ("%s (%s <= %d)", blurb,
+                            g_param_spec_get_name (pspec),
+                            ispec->maximum);
+
+  if (ispec->maximum == G_MAXINT32)
+    return g_strdup_printf ("%s (%s >= %d)", blurb,
+                            g_param_spec_get_name (pspec),
+                            ispec->minimum);
+
+  return g_strdup_printf ("%s (%d <= %s <= %d)", blurb,
+                          ispec->minimum,
+                          g_param_spec_get_name (pspec),
+                          ispec->maximum);
+}
+
+static gchar *
+gimp_param_spec_double_desc (GParamSpec *pspec)
+{
+  GParamSpecDouble *dspec = G_PARAM_SPEC_DOUBLE (pspec);
+  const gchar      *blurb = gimp_param_spec_get_blurb (pspec);
+
+  if (dspec->minimum == - G_MAXDOUBLE && dspec->maximum == G_MAXDOUBLE)
+    return g_strdup (blurb);
+
+  if (dspec->minimum == - G_MAXDOUBLE)
+    return g_strdup_printf ("%s (%s <= %g)", blurb,
+                            g_param_spec_get_name (pspec),
+                            dspec->maximum);
+
+  if (dspec->maximum == G_MAXDOUBLE)
+    return g_strdup_printf ("%s (%s >= %g)", blurb,
+                            g_param_spec_get_name (pspec),
+                            dspec->minimum);
+
+  return g_strdup_printf ("%s (%g <= %s <= %g)", blurb,
+                          dspec->minimum,
+                          g_param_spec_get_name (pspec),
+                          dspec->maximum);
+}
+
+static gchar *
+gimp_param_spec_enum_desc (GParamSpec *pspec)
+{
+  const gchar    *blurb      = gimp_param_spec_get_blurb (pspec);
+  GString        *str        = g_string_new (blurb);
+  GEnumClass     *enum_class = g_type_class_peek (pspec->value_type);
+  GEnumValue     *enum_value;
+  GSList         *excluded;
+  gint            i, n;
+
+  if (GIMP_IS_PARAM_SPEC_ENUM (pspec))
+    excluded = GIMP_PARAM_SPEC_ENUM (pspec)->excluded_values;
+  else
+    excluded = NULL;
+
+  g_string_append (str, " { ");
+
+  for (i = 0, n = 0, enum_value = enum_class->values;
+       i < enum_class->n_values;
+       i++, enum_value++)
+    {
+      GSList *list;
+      gchar  *name;
+
+      for (list = excluded; list; list = list->next)
+        {
+          gint value = GPOINTER_TO_INT (list->data);
+
+          if (value == enum_value->value)
+            break;
+        }
+
+      if (list)
+        continue;
+
+      if (n > 0)
+        g_string_append (str, ", ");
+
+      if (G_LIKELY (g_str_has_prefix (enum_value->value_name, "GIMP_")))
+        name = gimp_canonicalize_identifier (enum_value->value_name + 5);
+      else
+        name = gimp_canonicalize_identifier (enum_value->value_name);
+
+      g_string_append (str, name);
+      g_free (name);
+
+      g_string_append_printf (str, " (%d)", enum_value->value);
+
+      n++;
+    }
+
+  g_string_append (str, " }");
+
+  return g_string_free (str, FALSE);
+}
+
+/**
+ * gimp_param_spec_get_desc:
+ * @pspec: a #GParamSpec
+ *
+ * This function creates a description of the passed @pspec, which is
+ * suitable for use in the PDB.  Actually, it currently only deals with
+ * parameter types used in the PDB and should not be used for anything
+ * else.
+ *
+ * Return value: A newly allocated string describing the parameter.
+ */
+gchar *
+gimp_param_spec_get_desc (GParamSpec *pspec)
+{
+  g_return_val_if_fail (G_IS_PARAM_SPEC (pspec), NULL);
+
+  if (GIMP_IS_PARAM_SPEC_UNIT (pspec))
+    {
+    }
+  else if (GIMP_IS_PARAM_SPEC_INT32 (pspec))
+    {
+      return gimp_param_spec_int32_desc (pspec);
+    }
+  else
+    {
+      switch (G_TYPE_FUNDAMENTAL (pspec->value_type))
+        {
+        case G_TYPE_BOOLEAN:
+          return gimp_param_spec_boolean_desc (pspec);
+
+        case G_TYPE_DOUBLE:
+          return gimp_param_spec_double_desc (pspec);
+
+        case G_TYPE_ENUM:
+          return gimp_param_spec_enum_desc (pspec);
+        }
+    }
+
+  return g_strdup (g_param_spec_get_blurb (pspec));
+}
diff --git a/app/core/gimpparamspecs-desc.h b/app/core/gimpparamspecs-desc.h
new file mode 100644
index 0000000..1e6ea2d
--- /dev/null
+++ b/app/core/gimpparamspecs-desc.h
@@ -0,0 +1,25 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_PARAM_SPECS_DESC_H__
+#define __GIMP_PARAM_SPECS_DESC_H__
+
+
+gchar * gimp_param_spec_get_desc (GParamSpec *pspec);
+
+
+#endif  /*  __GIMP_PARAM_SPECS_DESC_H__  */
diff --git a/app/core/gimpparamspecs-duplicate.c b/app/core/gimpparamspecs-duplicate.c
new file mode 100644
index 0000000..ff0587b
--- /dev/null
+++ b/app/core/gimpparamspecs-duplicate.c
@@ -0,0 +1,269 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpparamspecs-duplicate.c
+ * Copyright (C) 2008-2014 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <cairo.h>
+#include <gegl.h>
+#include <gegl-paramspecs.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "libgimpcolor/gimpcolor.h"
+#include "libgimpconfig/gimpconfig.h"
+
+#include "core-types.h"
+
+#include "gegl/gimp-gegl-utils.h"
+
+#include "gimpparamspecs.h"
+#include "gimpparamspecs-duplicate.h"
+
+
+/* FIXME: this code is not yet general as it should be (gegl tool only atm) */
+
+GParamSpec *
+gimp_param_spec_duplicate (GParamSpec *pspec)
+{
+  GParamSpec  *copy = NULL;
+  GParamFlags  flags;
+
+  g_return_val_if_fail (pspec != NULL, NULL);
+
+  flags = pspec->flags;
+
+  if (! gimp_gegl_param_spec_has_key (pspec, "role", "output-extent"))
+    flags |= GIMP_CONFIG_PARAM_SERIALIZE;
+
+  if (G_IS_PARAM_SPEC_STRING (pspec))
+    {
+      GParamSpecString *spec = G_PARAM_SPEC_STRING (pspec);
+
+      if (GEGL_IS_PARAM_SPEC_FILE_PATH (pspec))
+        {
+          copy = gimp_param_spec_config_path (pspec->name,
+                                              g_param_spec_get_nick (pspec),
+                                              g_param_spec_get_blurb (pspec),
+                                              GIMP_CONFIG_PATH_FILE,
+                                              spec->default_value,
+                                              flags);
+        }
+      else
+        {
+          copy = g_param_spec_string (pspec->name,
+                                      g_param_spec_get_nick (pspec),
+                                      g_param_spec_get_blurb (pspec),
+                                      spec->default_value,
+                                      flags);
+        }
+    }
+  else if (G_IS_PARAM_SPEC_BOOLEAN (pspec))
+    {
+      GParamSpecBoolean *spec = G_PARAM_SPEC_BOOLEAN (pspec);
+
+      copy = g_param_spec_boolean (pspec->name,
+                                   g_param_spec_get_nick (pspec),
+                                   g_param_spec_get_blurb (pspec),
+                                   spec->default_value,
+                                   flags);
+    }
+  else if (G_IS_PARAM_SPEC_ENUM (pspec))
+    {
+      GParamSpecEnum *spec = G_PARAM_SPEC_ENUM (pspec);
+
+      copy = g_param_spec_enum (pspec->name,
+                                g_param_spec_get_nick (pspec),
+                                g_param_spec_get_blurb (pspec),
+                                G_TYPE_FROM_CLASS (spec->enum_class),
+                                spec->default_value,
+                                flags);
+    }
+  else if (GEGL_IS_PARAM_SPEC_DOUBLE (pspec))
+    {
+      GeglParamSpecDouble *gspec = GEGL_PARAM_SPEC_DOUBLE (pspec);
+      GParamSpecDouble    *spec  = G_PARAM_SPEC_DOUBLE (pspec);
+
+      copy = gegl_param_spec_double (pspec->name,
+                                     g_param_spec_get_nick (pspec),
+                                     g_param_spec_get_blurb (pspec),
+                                     spec->minimum,
+                                     spec->maximum,
+                                     spec->default_value,
+                                     gspec->ui_minimum,
+                                     gspec->ui_maximum,
+                                     gspec->ui_gamma,
+                                     flags);
+      gegl_param_spec_double_set_steps (GEGL_PARAM_SPEC_DOUBLE (copy),
+                                        gspec->ui_step_small,
+                                        gspec->ui_step_big);
+      gegl_param_spec_double_set_digits (GEGL_PARAM_SPEC_DOUBLE (copy),
+                                         gspec->ui_digits);
+    }
+  else if (G_IS_PARAM_SPEC_DOUBLE (pspec))
+    {
+      GParamSpecDouble *spec = G_PARAM_SPEC_DOUBLE (pspec);
+
+      copy = g_param_spec_double (pspec->name,
+                                  g_param_spec_get_nick (pspec),
+                                  g_param_spec_get_blurb (pspec),
+                                  spec->minimum,
+                                  spec->maximum,
+                                  spec->default_value,
+                                  flags);
+    }
+  else if (G_IS_PARAM_SPEC_FLOAT (pspec))
+    {
+      GParamSpecFloat *spec = G_PARAM_SPEC_FLOAT (pspec);
+
+      copy = g_param_spec_float (pspec->name,
+                                 g_param_spec_get_nick (pspec),
+                                 g_param_spec_get_blurb (pspec),
+                                 spec->minimum,
+                                 spec->maximum,
+                                 spec->default_value,
+                                 flags);
+    }
+  else if (GEGL_IS_PARAM_SPEC_INT (pspec))
+    {
+      GeglParamSpecInt *gspec = GEGL_PARAM_SPEC_INT (pspec);
+      GParamSpecInt    *spec  = G_PARAM_SPEC_INT (pspec);
+
+      copy = gegl_param_spec_int (pspec->name,
+                                  g_param_spec_get_nick (pspec),
+                                  g_param_spec_get_blurb (pspec),
+                                  spec->minimum,
+                                  spec->maximum,
+                                  spec->default_value,
+                                  gspec->ui_minimum,
+                                  gspec->ui_maximum,
+                                  gspec->ui_gamma,
+                                  flags);
+      gegl_param_spec_int_set_steps (GEGL_PARAM_SPEC_INT (copy),
+                                     gspec->ui_step_small,
+                                     gspec->ui_step_big);
+    }
+  else if (GEGL_IS_PARAM_SPEC_SEED (pspec))
+    {
+      GParamSpecUInt    *spec  = G_PARAM_SPEC_UINT (pspec);
+      GeglParamSpecSeed *gspec = GEGL_PARAM_SPEC_SEED (pspec);
+
+      copy = gegl_param_spec_seed (pspec->name,
+                                   g_param_spec_get_nick (pspec),
+                                   g_param_spec_get_blurb (pspec),
+                                   pspec->flags |
+                                   GIMP_CONFIG_PARAM_SERIALIZE);
+
+      G_PARAM_SPEC_UINT (copy)->minimum = spec->minimum;
+      G_PARAM_SPEC_UINT (copy)->maximum = spec->maximum;
+
+      GEGL_PARAM_SPEC_SEED (copy)->ui_minimum = gspec->ui_minimum;
+      GEGL_PARAM_SPEC_SEED (copy)->ui_maximum = gspec->ui_maximum;
+    }
+  else if (G_IS_PARAM_SPEC_INT (pspec))
+    {
+      GParamSpecInt *spec = G_PARAM_SPEC_INT (pspec);
+
+      copy = g_param_spec_int (pspec->name,
+                               g_param_spec_get_nick (pspec),
+                               g_param_spec_get_blurb (pspec),
+                               spec->minimum,
+                               spec->maximum,
+                               spec->default_value,
+                               flags);
+    }
+  else if (G_IS_PARAM_SPEC_UINT (pspec))
+    {
+      GParamSpecUInt *spec = G_PARAM_SPEC_UINT (pspec);
+
+      copy = g_param_spec_uint (pspec->name,
+                                g_param_spec_get_nick (pspec),
+                                g_param_spec_get_blurb (pspec),
+                                spec->minimum,
+                                spec->maximum,
+                                spec->default_value,
+                                flags);
+    }
+  else if (GIMP_IS_PARAM_SPEC_RGB (pspec))
+    {
+      GValue  value = G_VALUE_INIT;
+      GimpRGB color;
+
+      g_value_init (&value, GIMP_TYPE_RGB);
+      g_param_value_set_default (pspec, &value);
+      gimp_value_get_rgb (&value, &color);
+      g_value_unset (&value);
+
+      copy = gimp_param_spec_rgb (pspec->name,
+                                  g_param_spec_get_nick (pspec),
+                                  g_param_spec_get_blurb (pspec),
+                                  gimp_param_spec_rgb_has_alpha (pspec),
+                                  &color,
+                                  flags);
+    }
+  else if (GEGL_IS_PARAM_SPEC_COLOR (pspec))
+    {
+      GeglColor *gegl_color;
+      GimpRGB    gimp_color;
+      gdouble    r = 0.0;
+      gdouble    g = 0.0;
+      gdouble    b = 0.0;
+      gdouble    a = 1.0;
+      GValue     value = G_VALUE_INIT;
+
+      g_value_init (&value, GEGL_TYPE_COLOR);
+      g_param_value_set_default (pspec, &value);
+
+      gegl_color = g_value_get_object (&value);
+      if (gegl_color)
+        gegl_color_get_rgba (gegl_color, &r, &g, &b, &a);
+
+      gimp_rgba_set (&gimp_color, r, g, b, a);
+
+      g_value_unset (&value);
+
+      copy = gimp_param_spec_rgb (pspec->name,
+                                  g_param_spec_get_nick (pspec),
+                                  g_param_spec_get_blurb (pspec),
+                                  TRUE,
+                                  &gimp_color,
+                                  flags);
+    }
+  else if (G_IS_PARAM_SPEC_OBJECT (pspec) ||
+           G_IS_PARAM_SPEC_POINTER (pspec))
+    {
+      /*  silently ignore object properties  */
+    }
+  else
+    {
+      g_warning ("%s: not supported: %s (%s)\n", G_STRFUNC,
+                 g_type_name (G_TYPE_FROM_INSTANCE (pspec)), pspec->name);
+    }
+
+  if (copy)
+    {
+      GQuark      quark = g_quark_from_static_string ("gegl-property-keys");
+      GHashTable *keys  = g_param_spec_get_qdata (pspec, quark);
+
+      if (keys)
+        g_param_spec_set_qdata_full (copy, quark, g_hash_table_ref (keys),
+                                     (GDestroyNotify) g_hash_table_unref);
+    }
+
+  return copy;
+}
diff --git a/app/core/gimpparamspecs-duplicate.h b/app/core/gimpparamspecs-duplicate.h
new file mode 100644
index 0000000..2bb1432
--- /dev/null
+++ b/app/core/gimpparamspecs-duplicate.h
@@ -0,0 +1,28 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpparamspecs-duplicate.h
+ * Copyright (C) 2008-2009 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_PARAM_SPECS_DUPLICATE_H__
+#define __GIMP_PARAM_SPECS_DUPLICATE_H__
+
+
+GParamSpec * gimp_param_spec_duplicate (GParamSpec *pspec);
+
+
+#endif  /*  __GIMP_PARAM_SPECS_DUPLICATE_H__  */
diff --git a/app/core/gimpparamspecs.c b/app/core/gimpparamspecs.c
new file mode 100644
index 0000000..17ba6a5
--- /dev/null
+++ b/app/core/gimpparamspecs.c
@@ -0,0 +1,2925 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+
+#include "core-types.h"
+
+#include "gimp.h"
+#include "gimpimage.h"
+#include "gimplayer.h"
+#include "gimplayermask.h"
+#include "gimpparamspecs.h"
+#include "gimpselection.h"
+
+#include "vectors/gimpvectors.h"
+
+
+/*
+ * GIMP_TYPE_INT32
+ */
+
+GType
+gimp_int32_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    {
+      const GTypeInfo info = { 0, };
+
+      type = g_type_register_static (G_TYPE_INT, "GimpInt32", &info, 0);
+    }
+
+  return type;
+}
+
+
+/*
+ * GIMP_TYPE_PARAM_INT32
+ */
+
+static void   gimp_param_int32_class_init (GParamSpecClass *klass);
+static void   gimp_param_int32_init       (GParamSpec      *pspec);
+
+GType
+gimp_param_int32_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    {
+      const GTypeInfo info =
+      {
+        sizeof (GParamSpecClass),
+        NULL, NULL,
+        (GClassInitFunc) gimp_param_int32_class_init,
+        NULL, NULL,
+        sizeof (GimpParamSpecInt32),
+        0,
+        (GInstanceInitFunc) gimp_param_int32_init
+      };
+
+      type = g_type_register_static (G_TYPE_PARAM_INT,
+                                     "GimpParamInt32", &info, 0);
+    }
+
+  return type;
+}
+
+static void
+gimp_param_int32_class_init (GParamSpecClass *klass)
+{
+  klass->value_type = GIMP_TYPE_INT32;
+}
+
+static void
+gimp_param_int32_init (GParamSpec *pspec)
+{
+}
+
+GParamSpec *
+gimp_param_spec_int32 (const gchar *name,
+                       const gchar *nick,
+                       const gchar *blurb,
+                       gint         minimum,
+                       gint         maximum,
+                       gint         default_value,
+                       GParamFlags  flags)
+{
+  GParamSpecInt *ispec;
+
+  g_return_val_if_fail (minimum >= G_MININT32, NULL);
+  g_return_val_if_fail (maximum <= G_MAXINT32, NULL);
+  g_return_val_if_fail (default_value >= minimum &&
+                        default_value <= maximum, NULL);
+
+  ispec = g_param_spec_internal (GIMP_TYPE_PARAM_INT32,
+                                 name, nick, blurb, flags);
+
+  ispec->minimum       = minimum;
+  ispec->maximum       = maximum;
+  ispec->default_value = default_value;
+
+  return G_PARAM_SPEC (ispec);
+}
+
+
+/*
+ * GIMP_TYPE_INT16
+ */
+
+GType
+gimp_int16_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    {
+      const GTypeInfo info = { 0, };
+
+      type = g_type_register_static (G_TYPE_INT, "GimpInt16", &info, 0);
+    }
+
+  return type;
+}
+
+
+/*
+ * GIMP_TYPE_PARAM_INT16
+ */
+
+static void   gimp_param_int16_class_init (GParamSpecClass *klass);
+static void   gimp_param_int16_init       (GParamSpec      *pspec);
+
+GType
+gimp_param_int16_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    {
+      const GTypeInfo info =
+      {
+        sizeof (GParamSpecClass),
+        NULL, NULL,
+        (GClassInitFunc) gimp_param_int16_class_init,
+        NULL, NULL,
+        sizeof (GimpParamSpecInt16),
+        0,
+        (GInstanceInitFunc) gimp_param_int16_init
+      };
+
+      type = g_type_register_static (G_TYPE_PARAM_INT,
+                                     "GimpParamInt16", &info, 0);
+    }
+
+  return type;
+}
+
+static void
+gimp_param_int16_class_init (GParamSpecClass *klass)
+{
+  klass->value_type = GIMP_TYPE_INT16;
+}
+
+static void
+gimp_param_int16_init (GParamSpec *pspec)
+{
+}
+
+GParamSpec *
+gimp_param_spec_int16 (const gchar *name,
+                       const gchar *nick,
+                       const gchar *blurb,
+                       gint         minimum,
+                       gint         maximum,
+                       gint         default_value,
+                       GParamFlags  flags)
+{
+  GParamSpecInt *ispec;
+
+  g_return_val_if_fail (minimum >= G_MININT16, NULL);
+  g_return_val_if_fail (maximum <= G_MAXINT16, NULL);
+  g_return_val_if_fail (default_value >= minimum &&
+                        default_value <= maximum, NULL);
+
+  ispec = g_param_spec_internal (GIMP_TYPE_PARAM_INT16,
+                                 name, nick, blurb, flags);
+
+  ispec->minimum       = minimum;
+  ispec->maximum       = maximum;
+  ispec->default_value = default_value;
+
+  return G_PARAM_SPEC (ispec);
+}
+
+
+/*
+ * GIMP_TYPE_INT8
+ */
+
+GType
+gimp_int8_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    {
+      const GTypeInfo info = { 0, };
+
+      type = g_type_register_static (G_TYPE_UINT, "GimpInt8", &info, 0);
+    }
+
+  return type;
+}
+
+
+/*
+ * GIMP_TYPE_PARAM_INT8
+ */
+
+static void   gimp_param_int8_class_init (GParamSpecClass *klass);
+static void   gimp_param_int8_init       (GParamSpec      *pspec);
+
+GType
+gimp_param_int8_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    {
+      const GTypeInfo info =
+      {
+        sizeof (GParamSpecClass),
+        NULL, NULL,
+        (GClassInitFunc) gimp_param_int8_class_init,
+        NULL, NULL,
+        sizeof (GimpParamSpecInt8),
+        0,
+        (GInstanceInitFunc) gimp_param_int8_init
+      };
+
+      type = g_type_register_static (G_TYPE_PARAM_UINT,
+                                     "GimpParamInt8", &info, 0);
+    }
+
+  return type;
+}
+
+static void
+gimp_param_int8_class_init (GParamSpecClass *klass)
+{
+  klass->value_type = GIMP_TYPE_INT8;
+}
+
+static void
+gimp_param_int8_init (GParamSpec *pspec)
+{
+}
+
+GParamSpec *
+gimp_param_spec_int8 (const gchar *name,
+                      const gchar *nick,
+                      const gchar *blurb,
+                      guint        minimum,
+                      guint        maximum,
+                      guint        default_value,
+                      GParamFlags  flags)
+{
+  GParamSpecInt *ispec;
+
+  g_return_val_if_fail (maximum <= G_MAXUINT8, NULL);
+  g_return_val_if_fail (default_value >= minimum &&
+                        default_value <= maximum, NULL);
+
+  ispec = g_param_spec_internal (GIMP_TYPE_PARAM_INT8,
+                                 name, nick, blurb, flags);
+
+  ispec->minimum       = minimum;
+  ispec->maximum       = maximum;
+  ispec->default_value = default_value;
+
+  return G_PARAM_SPEC (ispec);
+}
+
+
+/*
+ * GIMP_TYPE_PARAM_STRING
+ */
+
+static void       gimp_param_string_class_init (GParamSpecClass *klass);
+static void       gimp_param_string_init       (GParamSpec      *pspec);
+static gboolean   gimp_param_string_validate   (GParamSpec      *pspec,
+                                                GValue          *value);
+
+static GParamSpecClass * gimp_param_string_parent_class = NULL;
+
+GType
+gimp_param_string_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    {
+      const GTypeInfo info =
+      {
+        sizeof (GParamSpecClass),
+        NULL, NULL,
+        (GClassInitFunc) gimp_param_string_class_init,
+        NULL, NULL,
+        sizeof (GimpParamSpecString),
+        0,
+        (GInstanceInitFunc) gimp_param_string_init
+      };
+
+      type = g_type_register_static (G_TYPE_PARAM_STRING,
+                                     "GimpParamString", &info, 0);
+    }
+
+  return type;
+}
+
+static void
+gimp_param_string_class_init (GParamSpecClass *klass)
+{
+  gimp_param_string_parent_class = g_type_class_peek_parent (klass);
+
+  klass->value_type     = G_TYPE_STRING;
+  klass->value_validate = gimp_param_string_validate;
+}
+
+static void
+gimp_param_string_init (GParamSpec *pspec)
+{
+  GimpParamSpecString *sspec = GIMP_PARAM_SPEC_STRING (pspec);
+
+  G_PARAM_SPEC_STRING (pspec)->ensure_non_null = TRUE;
+
+  sspec->allow_non_utf8 = FALSE;
+  sspec->non_empty      = FALSE;
+}
+
+static gboolean
+gimp_param_string_validate (GParamSpec *pspec,
+                            GValue     *value)
+{
+  GimpParamSpecString *sspec  = GIMP_PARAM_SPEC_STRING (pspec);
+  gchar               *string = value->data[0].v_pointer;
+
+  if (gimp_param_string_parent_class->value_validate (pspec, value))
+    return TRUE;
+
+  if (string)
+    {
+      gchar *s;
+
+      if (sspec->non_empty && ! string[0])
+        {
+          if (!(value->data[1].v_uint & G_VALUE_NOCOPY_CONTENTS))
+            g_free (string);
+          else
+            value->data[1].v_uint &= ~G_VALUE_NOCOPY_CONTENTS;
+
+          value->data[0].v_pointer = g_strdup ("none");
+          return TRUE;
+        }
+
+      if (! sspec->allow_non_utf8 &&
+          ! g_utf8_validate (string, -1, (const gchar **) &s))
+        {
+          if (value->data[1].v_uint & G_VALUE_NOCOPY_CONTENTS)
+            {
+              value->data[0].v_pointer = g_strdup (string);
+              value->data[1].v_uint &= ~G_VALUE_NOCOPY_CONTENTS;
+              string = value->data[0].v_pointer;
+            }
+
+          for (s = string; *s; s++)
+            if (*s < ' ')
+              *s = '?';
+
+          return TRUE;
+        }
+    }
+  else if (sspec->non_empty)
+    {
+      value->data[1].v_uint &= ~G_VALUE_NOCOPY_CONTENTS;
+      value->data[0].v_pointer = g_strdup ("none");
+      return TRUE;
+    }
+
+  return FALSE;
+}
+
+GParamSpec *
+gimp_param_spec_string (const gchar *name,
+                        const gchar *nick,
+                        const gchar *blurb,
+                        gboolean     allow_non_utf8,
+                        gboolean     null_ok,
+                        gboolean     non_empty,
+                        const gchar *default_value,
+                        GParamFlags  flags)
+{
+  GimpParamSpecString *sspec;
+
+  g_return_val_if_fail (! (null_ok && non_empty), NULL);
+
+  sspec = g_param_spec_internal (GIMP_TYPE_PARAM_STRING,
+                                 name, nick, blurb, flags);
+
+  if (sspec)
+    {
+      g_free (G_PARAM_SPEC_STRING (sspec)->default_value);
+      G_PARAM_SPEC_STRING (sspec)->default_value = g_strdup (default_value);
+
+      G_PARAM_SPEC_STRING (sspec)->ensure_non_null = null_ok ? FALSE : TRUE;
+
+      sspec->allow_non_utf8 = allow_non_utf8 ? TRUE : FALSE;
+      sspec->non_empty      = non_empty      ? TRUE : FALSE;
+    }
+
+  return G_PARAM_SPEC (sspec);
+}
+
+
+/*
+ * GIMP_TYPE_PARAM_ENUM
+ */
+
+static void       gimp_param_enum_class_init (GParamSpecClass *klass);
+static void       gimp_param_enum_init       (GParamSpec      *pspec);
+static void       gimp_param_enum_finalize   (GParamSpec      *pspec);
+static gboolean   gimp_param_enum_validate   (GParamSpec      *pspec,
+                                              GValue          *value);
+
+GType
+gimp_param_enum_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    {
+      const GTypeInfo info =
+      {
+        sizeof (GParamSpecClass),
+        NULL, NULL,
+        (GClassInitFunc) gimp_param_enum_class_init,
+        NULL, NULL,
+        sizeof (GimpParamSpecEnum),
+        0,
+        (GInstanceInitFunc) gimp_param_enum_init
+      };
+
+      type = g_type_register_static (G_TYPE_PARAM_ENUM,
+                                     "GimpParamEnum", &info, 0);
+    }
+
+  return type;
+}
+
+static void
+gimp_param_enum_class_init (GParamSpecClass *klass)
+{
+  klass->value_type     = G_TYPE_ENUM;
+  klass->finalize       = gimp_param_enum_finalize;
+  klass->value_validate = gimp_param_enum_validate;
+}
+
+static void
+gimp_param_enum_init (GParamSpec *pspec)
+{
+  GimpParamSpecEnum *espec = GIMP_PARAM_SPEC_ENUM (pspec);
+
+  espec->excluded_values = NULL;
+}
+
+static void
+gimp_param_enum_finalize (GParamSpec *pspec)
+{
+  GimpParamSpecEnum *espec = GIMP_PARAM_SPEC_ENUM (pspec);
+  GParamSpecClass   *parent_class;
+
+  parent_class = g_type_class_peek (g_type_parent (GIMP_TYPE_PARAM_ENUM));
+
+  g_slist_free (espec->excluded_values);
+
+  parent_class->finalize (pspec);
+}
+
+static gboolean
+gimp_param_enum_validate (GParamSpec *pspec,
+                          GValue     *value)
+{
+  GimpParamSpecEnum *espec  = GIMP_PARAM_SPEC_ENUM (pspec);
+  GParamSpecClass   *parent_class;
+  GSList            *list;
+
+  parent_class = g_type_class_peek (g_type_parent (GIMP_TYPE_PARAM_ENUM));
+
+  if (parent_class->value_validate (pspec, value))
+    return TRUE;
+
+  for (list = espec->excluded_values; list; list = g_slist_next (list))
+    {
+      if (GPOINTER_TO_INT (list->data) == value->data[0].v_long)
+        {
+          value->data[0].v_long = G_PARAM_SPEC_ENUM (pspec)->default_value;
+          return TRUE;
+        }
+    }
+
+  return FALSE;
+}
+
+GParamSpec *
+gimp_param_spec_enum (const gchar *name,
+                      const gchar *nick,
+                      const gchar *blurb,
+                      GType        enum_type,
+                      gint         default_value,
+                      GParamFlags  flags)
+{
+  GimpParamSpecEnum *espec;
+  GEnumClass        *enum_class;
+
+  g_return_val_if_fail (G_TYPE_IS_ENUM (enum_type), NULL);
+
+  enum_class = g_type_class_ref (enum_type);
+
+  g_return_val_if_fail (g_enum_get_value (enum_class, default_value) != NULL,
+                        NULL);
+
+  espec = g_param_spec_internal (GIMP_TYPE_PARAM_ENUM,
+                                 name, nick, blurb, flags);
+
+  G_PARAM_SPEC_ENUM (espec)->enum_class    = enum_class;
+  G_PARAM_SPEC_ENUM (espec)->default_value = default_value;
+  G_PARAM_SPEC (espec)->value_type         = enum_type;
+
+  return G_PARAM_SPEC (espec);
+}
+
+void
+gimp_param_spec_enum_exclude_value (GimpParamSpecEnum *espec,
+                                    gint               value)
+{
+  g_return_if_fail (GIMP_IS_PARAM_SPEC_ENUM (espec));
+  g_return_if_fail (g_enum_get_value (G_PARAM_SPEC_ENUM (espec)->enum_class,
+                                      value) != NULL);
+
+  espec->excluded_values = g_slist_prepend (espec->excluded_values,
+                                            GINT_TO_POINTER (value));
+}
+
+
+/*
+ * GIMP_TYPE_IMAGE_ID
+ */
+
+GType
+gimp_image_id_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    {
+      const GTypeInfo info = { 0, };
+
+      type = g_type_register_static (G_TYPE_INT, "GimpImageID", &info, 0);
+    }
+
+  return type;
+}
+
+
+/*
+ * GIMP_TYPE_PARAM_IMAGE_ID
+ */
+
+static void       gimp_param_image_id_class_init  (GParamSpecClass *klass);
+static void       gimp_param_image_id_init        (GParamSpec      *pspec);
+static void       gimp_param_image_id_set_default (GParamSpec      *pspec,
+                                                   GValue          *value);
+static gboolean   gimp_param_image_id_validate    (GParamSpec      *pspec,
+                                                   GValue          *value);
+static gint       gimp_param_image_id_values_cmp  (GParamSpec      *pspec,
+                                                   const GValue    *value1,
+                                                   const GValue    *value2);
+
+GType
+gimp_param_image_id_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    {
+      const GTypeInfo info =
+      {
+        sizeof (GParamSpecClass),
+        NULL, NULL,
+        (GClassInitFunc) gimp_param_image_id_class_init,
+        NULL, NULL,
+        sizeof (GimpParamSpecImageID),
+        0,
+        (GInstanceInitFunc) gimp_param_image_id_init
+      };
+
+      type = g_type_register_static (G_TYPE_PARAM_INT,
+                                     "GimpParamImageID", &info, 0);
+    }
+
+  return type;
+}
+
+static void
+gimp_param_image_id_class_init (GParamSpecClass *klass)
+{
+  klass->value_type        = GIMP_TYPE_IMAGE_ID;
+  klass->value_set_default = gimp_param_image_id_set_default;
+  klass->value_validate    = gimp_param_image_id_validate;
+  klass->values_cmp        = gimp_param_image_id_values_cmp;
+}
+
+static void
+gimp_param_image_id_init (GParamSpec *pspec)
+{
+  GimpParamSpecImageID *ispec = GIMP_PARAM_SPEC_IMAGE_ID (pspec);
+
+  ispec->gimp    = NULL;
+  ispec->none_ok = FALSE;
+}
+
+static void
+gimp_param_image_id_set_default (GParamSpec *pspec,
+                                 GValue     *value)
+{
+  value->data[0].v_int = -1;
+}
+
+static gboolean
+gimp_param_image_id_validate (GParamSpec *pspec,
+                              GValue     *value)
+{
+  GimpParamSpecImageID *ispec    = GIMP_PARAM_SPEC_IMAGE_ID (pspec);
+  gint                  image_id = value->data[0].v_int;
+  GimpImage            *image;
+
+  if (ispec->none_ok && (image_id == 0 || image_id == -1))
+    return FALSE;
+
+  image = gimp_image_get_by_ID (ispec->gimp, image_id);
+
+  if (! GIMP_IS_IMAGE (image))
+    {
+      value->data[0].v_int = -1;
+      return TRUE;
+    }
+
+  return FALSE;
+}
+
+static gint
+gimp_param_image_id_values_cmp (GParamSpec   *pspec,
+                                const GValue *value1,
+                                const GValue *value2)
+{
+  gint image_id1 = value1->data[0].v_int;
+  gint image_id2 = value2->data[0].v_int;
+
+  /*  try to return at least *something*, it's useless anyway...  */
+
+  if (image_id1 < image_id2)
+    return -1;
+  else if (image_id1 > image_id2)
+    return 1;
+  else
+    return 0;
+}
+
+GParamSpec *
+gimp_param_spec_image_id (const gchar *name,
+                          const gchar *nick,
+                          const gchar *blurb,
+                          Gimp        *gimp,
+                          gboolean     none_ok,
+                          GParamFlags  flags)
+{
+  GimpParamSpecImageID *ispec;
+
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  ispec = g_param_spec_internal (GIMP_TYPE_PARAM_IMAGE_ID,
+                                 name, nick, blurb, flags);
+
+  ispec->gimp    = gimp;
+  ispec->none_ok = none_ok ? TRUE : FALSE;
+
+  return G_PARAM_SPEC (ispec);
+}
+
+GimpImage *
+gimp_value_get_image (const GValue *value,
+                      Gimp         *gimp)
+{
+  g_return_val_if_fail (GIMP_VALUE_HOLDS_IMAGE_ID (value), NULL);
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  return gimp_image_get_by_ID (gimp, value->data[0].v_int);
+}
+
+void
+gimp_value_set_image (GValue    *value,
+                      GimpImage *image)
+{
+  g_return_if_fail (GIMP_VALUE_HOLDS_IMAGE_ID (value));
+  g_return_if_fail (image == NULL || GIMP_IS_IMAGE (image));
+
+  value->data[0].v_int = image ? gimp_image_get_ID (image) : -1;
+}
+
+
+/*
+ * GIMP_TYPE_ITEM_ID
+ */
+
+GType
+gimp_item_id_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    {
+      const GTypeInfo info = { 0, };
+
+      type = g_type_register_static (G_TYPE_INT, "GimpItemID", &info, 0);
+    }
+
+  return type;
+}
+
+
+/*
+ * GIMP_TYPE_PARAM_ITEM_ID
+ */
+
+static void       gimp_param_item_id_class_init  (GParamSpecClass *klass);
+static void       gimp_param_item_id_init        (GParamSpec      *pspec);
+static void       gimp_param_item_id_set_default (GParamSpec      *pspec,
+                                                  GValue          *value);
+static gboolean   gimp_param_item_id_validate    (GParamSpec      *pspec,
+                                                  GValue          *value);
+static gint       gimp_param_item_id_values_cmp  (GParamSpec      *pspec,
+                                                  const GValue    *value1,
+                                                  const GValue    *value2);
+
+GType
+gimp_param_item_id_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    {
+      const GTypeInfo info =
+      {
+        sizeof (GParamSpecClass),
+        NULL, NULL,
+        (GClassInitFunc) gimp_param_item_id_class_init,
+        NULL, NULL,
+        sizeof (GimpParamSpecItemID),
+        0,
+        (GInstanceInitFunc) gimp_param_item_id_init
+      };
+
+      type = g_type_register_static (G_TYPE_PARAM_INT,
+                                     "GimpParamItemID", &info, 0);
+    }
+
+  return type;
+}
+
+static void
+gimp_param_item_id_class_init (GParamSpecClass *klass)
+{
+  klass->value_type        = GIMP_TYPE_ITEM_ID;
+  klass->value_set_default = gimp_param_item_id_set_default;
+  klass->value_validate    = gimp_param_item_id_validate;
+  klass->values_cmp        = gimp_param_item_id_values_cmp;
+}
+
+static void
+gimp_param_item_id_init (GParamSpec *pspec)
+{
+  GimpParamSpecItemID *ispec = GIMP_PARAM_SPEC_ITEM_ID (pspec);
+
+  ispec->gimp      = NULL;
+  ispec->item_type = GIMP_TYPE_ITEM;
+  ispec->none_ok   = FALSE;
+}
+
+static void
+gimp_param_item_id_set_default (GParamSpec *pspec,
+                                GValue     *value)
+{
+  value->data[0].v_int = -1;
+}
+
+static gboolean
+gimp_param_item_id_validate (GParamSpec *pspec,
+                             GValue     *value)
+{
+  GimpParamSpecItemID *ispec   = GIMP_PARAM_SPEC_ITEM_ID (pspec);
+  gint                 item_id = value->data[0].v_int;
+  GimpItem            *item;
+
+  if (ispec->none_ok && (item_id == 0 || item_id == -1))
+    return FALSE;
+
+  item = gimp_item_get_by_ID (ispec->gimp, item_id);
+
+  if (! item || ! g_type_is_a (G_TYPE_FROM_INSTANCE (item), ispec->item_type))
+    {
+      value->data[0].v_int = -1;
+      return TRUE;
+    }
+  else if (gimp_item_is_removed (item))
+    {
+      value->data[0].v_int = -1;
+      return TRUE;
+    }
+
+  return FALSE;
+}
+
+static gint
+gimp_param_item_id_values_cmp (GParamSpec   *pspec,
+                               const GValue *value1,
+                               const GValue *value2)
+{
+  gint item_id1 = value1->data[0].v_int;
+  gint item_id2 = value2->data[0].v_int;
+
+  /*  try to return at least *something*, it's useless anyway...  */
+
+  if (item_id1 < item_id2)
+    return -1;
+  else if (item_id1 > item_id2)
+    return 1;
+  else
+    return 0;
+}
+
+GParamSpec *
+gimp_param_spec_item_id (const gchar *name,
+                         const gchar *nick,
+                         const gchar *blurb,
+                         Gimp        *gimp,
+                         gboolean     none_ok,
+                         GParamFlags  flags)
+{
+  GimpParamSpecItemID *ispec;
+
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  ispec = g_param_spec_internal (GIMP_TYPE_PARAM_ITEM_ID,
+                                 name, nick, blurb, flags);
+
+  ispec->gimp    = gimp;
+  ispec->none_ok = none_ok;
+
+  return G_PARAM_SPEC (ispec);
+}
+
+GimpItem *
+gimp_value_get_item (const GValue *value,
+                     Gimp         *gimp)
+{
+  GimpItem *item;
+
+  g_return_val_if_fail (GIMP_VALUE_HOLDS_ITEM_ID (value), NULL);
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  item = gimp_item_get_by_ID (gimp, value->data[0].v_int);
+
+  if (item && ! GIMP_IS_ITEM (item))
+    return NULL;
+
+  return item;
+}
+
+void
+gimp_value_set_item (GValue   *value,
+                     GimpItem *item)
+{
+  g_return_if_fail (item == NULL || GIMP_IS_ITEM (item));
+
+  /* FIXME remove hack as soon as bug #375864 is fixed */
+
+  if (GIMP_VALUE_HOLDS_ITEM_ID (value))
+    {
+      value->data[0].v_int = item ? gimp_item_get_ID (item) : -1;
+    }
+  else if (GIMP_VALUE_HOLDS_DRAWABLE_ID (value) &&
+           (item == NULL || GIMP_IS_DRAWABLE (item)))
+    {
+      gimp_value_set_drawable (value, GIMP_DRAWABLE (item));
+    }
+  else if (GIMP_VALUE_HOLDS_LAYER_ID (value) &&
+           (item == NULL || GIMP_IS_LAYER (item)))
+    {
+      gimp_value_set_layer (value, GIMP_LAYER (item));
+    }
+  else if (GIMP_VALUE_HOLDS_CHANNEL_ID (value) &&
+           (item == NULL || GIMP_IS_CHANNEL (item)))
+    {
+      gimp_value_set_channel (value, GIMP_CHANNEL (item));
+    }
+  else if (GIMP_VALUE_HOLDS_LAYER_MASK_ID (value) &&
+           (item == NULL || GIMP_IS_LAYER_MASK (item)))
+    {
+      gimp_value_set_layer_mask (value, GIMP_LAYER_MASK (item));
+    }
+  else if (GIMP_VALUE_HOLDS_SELECTION_ID (value) &&
+           (item == NULL || GIMP_IS_SELECTION (item)))
+    {
+      gimp_value_set_selection (value, GIMP_SELECTION (item));
+    }
+  else if (GIMP_VALUE_HOLDS_VECTORS_ID (value) &&
+           (item == NULL || GIMP_IS_VECTORS (item)))
+    {
+      gimp_value_set_vectors (value, GIMP_VECTORS (item));
+    }
+  else
+    {
+      g_return_if_reached ();
+    }
+}
+
+
+/*
+ * GIMP_TYPE_DRAWABLE_ID
+ */
+
+GType
+gimp_drawable_id_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    {
+      const GTypeInfo info = { 0, };
+
+      type = g_type_register_static (G_TYPE_INT, "GimpDrawableID", &info, 0);
+    }
+
+  return type;
+}
+
+
+/*
+ * GIMP_TYPE_PARAM_DRAWABLE_ID
+ */
+
+static void   gimp_param_drawable_id_class_init (GParamSpecClass *klass);
+static void   gimp_param_drawable_id_init       (GParamSpec      *pspec);
+
+GType
+gimp_param_drawable_id_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    {
+      const GTypeInfo info =
+      {
+        sizeof (GParamSpecClass),
+        NULL, NULL,
+        (GClassInitFunc) gimp_param_drawable_id_class_init,
+        NULL, NULL,
+        sizeof (GimpParamSpecDrawableID),
+        0,
+        (GInstanceInitFunc) gimp_param_drawable_id_init
+      };
+
+      type = g_type_register_static (GIMP_TYPE_PARAM_ITEM_ID,
+                                     "GimpParamDrawableID", &info, 0);
+    }
+
+  return type;
+}
+
+static void
+gimp_param_drawable_id_class_init (GParamSpecClass *klass)
+{
+  klass->value_type = GIMP_TYPE_DRAWABLE_ID;
+}
+
+static void
+gimp_param_drawable_id_init (GParamSpec *pspec)
+{
+  GimpParamSpecItemID *ispec = GIMP_PARAM_SPEC_ITEM_ID (pspec);
+
+  ispec->item_type = GIMP_TYPE_DRAWABLE;
+}
+
+GParamSpec *
+gimp_param_spec_drawable_id (const gchar *name,
+                             const gchar *nick,
+                             const gchar *blurb,
+                             Gimp        *gimp,
+                             gboolean     none_ok,
+                             GParamFlags  flags)
+{
+  GimpParamSpecItemID *ispec;
+
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  ispec = g_param_spec_internal (GIMP_TYPE_PARAM_DRAWABLE_ID,
+                                 name, nick, blurb, flags);
+
+  ispec->gimp    = gimp;
+  ispec->none_ok = none_ok ? TRUE : FALSE;
+
+  return G_PARAM_SPEC (ispec);
+}
+
+GimpDrawable *
+gimp_value_get_drawable (const GValue *value,
+                         Gimp         *gimp)
+{
+  GimpItem *item;
+
+  g_return_val_if_fail (GIMP_VALUE_HOLDS_DRAWABLE_ID (value), NULL);
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  item = gimp_item_get_by_ID (gimp, value->data[0].v_int);
+
+  if (item && ! GIMP_IS_DRAWABLE (item))
+    return NULL;
+
+  return GIMP_DRAWABLE (item);
+}
+
+void
+gimp_value_set_drawable (GValue       *value,
+                         GimpDrawable *drawable)
+{
+  g_return_if_fail (GIMP_VALUE_HOLDS_DRAWABLE_ID (value));
+  g_return_if_fail (drawable == NULL || GIMP_IS_DRAWABLE (drawable));
+
+  value->data[0].v_int = drawable ? gimp_item_get_ID (GIMP_ITEM (drawable)) : -1;
+}
+
+
+/*
+ * GIMP_TYPE_LAYER_ID
+ */
+
+GType
+gimp_layer_id_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    {
+      const GTypeInfo info = { 0, };
+
+      type = g_type_register_static (G_TYPE_INT, "GimpLayerID", &info, 0);
+    }
+
+  return type;
+}
+
+
+/*
+ * GIMP_TYPE_PARAM_LAYER_ID
+ */
+
+static void   gimp_param_layer_id_class_init (GParamSpecClass *klass);
+static void   gimp_param_layer_id_init       (GParamSpec      *pspec);
+
+GType
+gimp_param_layer_id_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    {
+      const GTypeInfo info =
+      {
+        sizeof (GParamSpecClass),
+        NULL, NULL,
+        (GClassInitFunc) gimp_param_layer_id_class_init,
+        NULL, NULL,
+        sizeof (GimpParamSpecLayerID),
+        0,
+        (GInstanceInitFunc) gimp_param_layer_id_init
+      };
+
+      type = g_type_register_static (GIMP_TYPE_PARAM_DRAWABLE_ID,
+                                     "GimpParamLayerID", &info, 0);
+    }
+
+  return type;
+}
+
+static void
+gimp_param_layer_id_class_init (GParamSpecClass *klass)
+{
+  klass->value_type = GIMP_TYPE_LAYER_ID;
+}
+
+static void
+gimp_param_layer_id_init (GParamSpec *pspec)
+{
+  GimpParamSpecItemID *ispec = GIMP_PARAM_SPEC_ITEM_ID (pspec);
+
+  ispec->item_type = GIMP_TYPE_LAYER;
+}
+
+GParamSpec *
+gimp_param_spec_layer_id (const gchar *name,
+                          const gchar *nick,
+                          const gchar *blurb,
+                          Gimp        *gimp,
+                          gboolean     none_ok,
+                          GParamFlags  flags)
+{
+  GimpParamSpecItemID *ispec;
+
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  ispec = g_param_spec_internal (GIMP_TYPE_PARAM_LAYER_ID,
+                                 name, nick, blurb, flags);
+
+  ispec->gimp    = gimp;
+  ispec->none_ok = none_ok ? TRUE : FALSE;
+
+  return G_PARAM_SPEC (ispec);
+}
+
+GimpLayer *
+gimp_value_get_layer (const GValue *value,
+                      Gimp         *gimp)
+{
+  GimpItem *item;
+
+  g_return_val_if_fail (GIMP_VALUE_HOLDS_LAYER_ID (value), NULL);
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  item = gimp_item_get_by_ID (gimp, value->data[0].v_int);
+
+  if (item && ! GIMP_IS_LAYER (item))
+    return NULL;
+
+  return GIMP_LAYER (item);
+}
+
+void
+gimp_value_set_layer (GValue    *value,
+                      GimpLayer *layer)
+{
+  g_return_if_fail (GIMP_VALUE_HOLDS_LAYER_ID (value));
+  g_return_if_fail (layer == NULL || GIMP_IS_LAYER (layer));
+
+  value->data[0].v_int = layer ? gimp_item_get_ID (GIMP_ITEM (layer)) : -1;
+}
+
+
+/*
+ * GIMP_TYPE_CHANNEL_ID
+ */
+
+GType
+gimp_channel_id_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    {
+      const GTypeInfo info = { 0, };
+
+      type = g_type_register_static (G_TYPE_INT, "GimpChannelID", &info, 0);
+    }
+
+  return type;
+}
+
+
+/*
+ * GIMP_TYPE_PARAM_CHANNEL_ID
+ */
+
+static void   gimp_param_channel_id_class_init (GParamSpecClass *klass);
+static void   gimp_param_channel_id_init       (GParamSpec      *pspec);
+
+GType
+gimp_param_channel_id_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    {
+      const GTypeInfo info =
+      {
+        sizeof (GParamSpecClass),
+        NULL, NULL,
+        (GClassInitFunc) gimp_param_channel_id_class_init,
+        NULL, NULL,
+        sizeof (GimpParamSpecChannelID),
+        0,
+        (GInstanceInitFunc) gimp_param_channel_id_init
+      };
+
+      type = g_type_register_static (GIMP_TYPE_PARAM_DRAWABLE_ID,
+                                     "GimpParamChannelID", &info, 0);
+    }
+
+  return type;
+}
+
+static void
+gimp_param_channel_id_class_init (GParamSpecClass *klass)
+{
+  klass->value_type = GIMP_TYPE_CHANNEL_ID;
+}
+
+static void
+gimp_param_channel_id_init (GParamSpec *pspec)
+{
+  GimpParamSpecItemID *ispec = GIMP_PARAM_SPEC_ITEM_ID (pspec);
+
+  ispec->item_type = GIMP_TYPE_CHANNEL;
+}
+
+GParamSpec *
+gimp_param_spec_channel_id (const gchar *name,
+                            const gchar *nick,
+                            const gchar *blurb,
+                            Gimp        *gimp,
+                            gboolean     none_ok,
+                            GParamFlags  flags)
+{
+  GimpParamSpecItemID *ispec;
+
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  ispec = g_param_spec_internal (GIMP_TYPE_PARAM_CHANNEL_ID,
+                                 name, nick, blurb, flags);
+
+  ispec->gimp    = gimp;
+  ispec->none_ok = none_ok ? TRUE : FALSE;
+
+  return G_PARAM_SPEC (ispec);
+}
+
+GimpChannel *
+gimp_value_get_channel (const GValue *value,
+                        Gimp         *gimp)
+{
+  GimpItem *item;
+
+  g_return_val_if_fail (GIMP_VALUE_HOLDS_CHANNEL_ID (value), NULL);
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  item = gimp_item_get_by_ID (gimp, value->data[0].v_int);
+
+  if (item && ! GIMP_IS_CHANNEL (item))
+    return NULL;
+
+  return GIMP_CHANNEL (item);
+}
+
+void
+gimp_value_set_channel (GValue      *value,
+                        GimpChannel *channel)
+{
+  g_return_if_fail (GIMP_VALUE_HOLDS_CHANNEL_ID (value));
+  g_return_if_fail (channel == NULL || GIMP_IS_CHANNEL (channel));
+
+  value->data[0].v_int = channel ? gimp_item_get_ID (GIMP_ITEM (channel)) : -1;
+}
+
+
+/*
+ * GIMP_TYPE_LAYER_MASK_ID
+ */
+
+GType
+gimp_layer_mask_id_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    {
+      const GTypeInfo info = { 0, };
+
+      type = g_type_register_static (G_TYPE_INT, "GimpLayerMaskID", &info, 0);
+    }
+
+  return type;
+}
+
+
+/*
+ * GIMP_TYPE_PARAM_LAYER_MASK_ID
+ */
+
+static void   gimp_param_layer_mask_id_class_init (GParamSpecClass *klass);
+static void   gimp_param_layer_mask_id_init       (GParamSpec      *pspec);
+
+GType
+gimp_param_layer_mask_id_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    {
+      const GTypeInfo info =
+      {
+        sizeof (GParamSpecClass),
+        NULL, NULL,
+        (GClassInitFunc) gimp_param_layer_mask_id_class_init,
+        NULL, NULL,
+        sizeof (GimpParamSpecLayerMaskID),
+        0,
+        (GInstanceInitFunc) gimp_param_layer_mask_id_init
+      };
+
+      type = g_type_register_static (GIMP_TYPE_PARAM_CHANNEL_ID,
+                                     "GimpParamLayerMaskID", &info, 0);
+    }
+
+  return type;
+}
+
+static void
+gimp_param_layer_mask_id_class_init (GParamSpecClass *klass)
+{
+  klass->value_type = GIMP_TYPE_LAYER_MASK_ID;
+}
+
+static void
+gimp_param_layer_mask_id_init (GParamSpec *pspec)
+{
+  GimpParamSpecItemID *ispec = GIMP_PARAM_SPEC_ITEM_ID (pspec);
+
+  ispec->item_type = GIMP_TYPE_LAYER_MASK;
+}
+
+GParamSpec *
+gimp_param_spec_layer_mask_id (const gchar *name,
+                               const gchar *nick,
+                               const gchar *blurb,
+                               Gimp        *gimp,
+                               gboolean     none_ok,
+                               GParamFlags  flags)
+{
+  GimpParamSpecItemID *ispec;
+
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  ispec = g_param_spec_internal (GIMP_TYPE_PARAM_LAYER_MASK_ID,
+                                 name, nick, blurb, flags);
+
+  ispec->gimp    = gimp;
+  ispec->none_ok = none_ok ? TRUE : FALSE;
+
+  return G_PARAM_SPEC (ispec);
+}
+
+GimpLayerMask *
+gimp_value_get_layer_mask (const GValue *value,
+                           Gimp         *gimp)
+{
+  GimpItem *item;
+
+  g_return_val_if_fail (GIMP_VALUE_HOLDS_LAYER_MASK_ID (value), NULL);
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  item = gimp_item_get_by_ID (gimp, value->data[0].v_int);
+
+  if (item && ! GIMP_IS_LAYER_MASK (item))
+    return NULL;
+
+  return GIMP_LAYER_MASK (item);
+}
+
+void
+gimp_value_set_layer_mask (GValue        *value,
+                           GimpLayerMask *layer_mask)
+{
+  g_return_if_fail (GIMP_VALUE_HOLDS_LAYER_MASK_ID (value));
+  g_return_if_fail (layer_mask == NULL || GIMP_IS_LAYER_MASK (layer_mask));
+
+  value->data[0].v_int = layer_mask ? gimp_item_get_ID (GIMP_ITEM (layer_mask)) : -1;
+}
+
+
+/*
+ * GIMP_TYPE_SELECTION_ID
+ */
+
+GType
+gimp_selection_id_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    {
+      const GTypeInfo info = { 0, };
+
+      type = g_type_register_static (G_TYPE_INT, "GimpSelectionID", &info, 0);
+    }
+
+  return type;
+}
+
+
+/*
+ * GIMP_TYPE_PARAM_SELECTION_ID
+ */
+
+static void   gimp_param_selection_id_class_init (GParamSpecClass *klass);
+static void   gimp_param_selection_id_init       (GParamSpec      *pspec);
+
+GType
+gimp_param_selection_id_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    {
+      const GTypeInfo info =
+      {
+        sizeof (GParamSpecClass),
+        NULL, NULL,
+        (GClassInitFunc) gimp_param_selection_id_class_init,
+        NULL, NULL,
+        sizeof (GimpParamSpecSelectionID),
+        0,
+        (GInstanceInitFunc) gimp_param_selection_id_init
+      };
+
+      type = g_type_register_static (GIMP_TYPE_PARAM_CHANNEL_ID,
+                                     "GimpParamSelectionID", &info, 0);
+    }
+
+  return type;
+}
+
+static void
+gimp_param_selection_id_class_init (GParamSpecClass *klass)
+{
+  klass->value_type = GIMP_TYPE_SELECTION_ID;
+}
+
+static void
+gimp_param_selection_id_init (GParamSpec *pspec)
+{
+  GimpParamSpecItemID *ispec = GIMP_PARAM_SPEC_ITEM_ID (pspec);
+
+  ispec->item_type = GIMP_TYPE_SELECTION;
+}
+
+GParamSpec *
+gimp_param_spec_selection_id (const gchar *name,
+                              const gchar *nick,
+                              const gchar *blurb,
+                              Gimp        *gimp,
+                              gboolean     none_ok,
+                              GParamFlags  flags)
+{
+  GimpParamSpecItemID *ispec;
+
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  ispec = g_param_spec_internal (GIMP_TYPE_PARAM_SELECTION_ID,
+                                 name, nick, blurb, flags);
+
+  ispec->gimp    = gimp;
+  ispec->none_ok = none_ok ? TRUE : FALSE;
+
+  return G_PARAM_SPEC (ispec);
+}
+
+GimpSelection *
+gimp_value_get_selection (const GValue *value,
+                          Gimp         *gimp)
+{
+  GimpItem *item;
+
+  g_return_val_if_fail (GIMP_VALUE_HOLDS_SELECTION_ID (value), NULL);
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  item = gimp_item_get_by_ID (gimp, value->data[0].v_int);
+
+  if (item && ! GIMP_IS_SELECTION (item))
+    return NULL;
+
+  return GIMP_SELECTION (item);
+}
+
+void
+gimp_value_set_selection (GValue        *value,
+                          GimpSelection *selection)
+{
+  g_return_if_fail (GIMP_VALUE_HOLDS_SELECTION_ID (value));
+  g_return_if_fail (selection == NULL || GIMP_IS_SELECTION (selection));
+
+  value->data[0].v_int = selection ? gimp_item_get_ID (GIMP_ITEM (selection)) : -1;
+}
+
+
+/*
+ * GIMP_TYPE_VECTORS_ID
+ */
+
+GType
+gimp_vectors_id_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    {
+      const GTypeInfo info = { 0, };
+
+      type = g_type_register_static (G_TYPE_INT, "GimpVectorsID", &info, 0);
+    }
+
+  return type;
+}
+
+
+/*
+ * GIMP_TYPE_PARAM_VECTORS_ID
+ */
+
+static void   gimp_param_vectors_id_class_init (GParamSpecClass *klass);
+static void   gimp_param_vectors_id_init       (GParamSpec      *pspec);
+
+GType
+gimp_param_vectors_id_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    {
+      const GTypeInfo info =
+      {
+        sizeof (GParamSpecClass),
+        NULL, NULL,
+        (GClassInitFunc) gimp_param_vectors_id_class_init,
+        NULL, NULL,
+        sizeof (GimpParamSpecVectorsID),
+        0,
+        (GInstanceInitFunc) gimp_param_vectors_id_init
+      };
+
+      type = g_type_register_static (GIMP_TYPE_PARAM_ITEM_ID,
+                                     "GimpParamVectorsID", &info, 0);
+    }
+
+  return type;
+}
+
+static void
+gimp_param_vectors_id_class_init (GParamSpecClass *klass)
+{
+  klass->value_type = GIMP_TYPE_VECTORS_ID;
+}
+
+static void
+gimp_param_vectors_id_init (GParamSpec *pspec)
+{
+  GimpParamSpecItemID *ispec = GIMP_PARAM_SPEC_ITEM_ID (pspec);
+
+  ispec->item_type = GIMP_TYPE_VECTORS;
+}
+
+GParamSpec *
+gimp_param_spec_vectors_id (const gchar *name,
+                            const gchar *nick,
+                            const gchar *blurb,
+                            Gimp        *gimp,
+                            gboolean     none_ok,
+                            GParamFlags  flags)
+{
+  GimpParamSpecItemID *ispec;
+
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  ispec = g_param_spec_internal (GIMP_TYPE_PARAM_VECTORS_ID,
+                                 name, nick, blurb, flags);
+
+  ispec->gimp    = gimp;
+  ispec->none_ok = none_ok ? TRUE : FALSE;
+
+  return G_PARAM_SPEC (ispec);
+}
+
+GimpVectors *
+gimp_value_get_vectors (const GValue *value,
+                        Gimp         *gimp)
+{
+  GimpItem *item;
+
+  g_return_val_if_fail (GIMP_VALUE_HOLDS_VECTORS_ID (value), NULL);
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  item = gimp_item_get_by_ID (gimp, value->data[0].v_int);
+
+  if (item && ! GIMP_IS_VECTORS (item))
+    return NULL;
+
+  return GIMP_VECTORS (item);
+}
+
+void
+gimp_value_set_vectors (GValue      *value,
+                        GimpVectors *vectors)
+{
+  g_return_if_fail (GIMP_VALUE_HOLDS_VECTORS_ID (value));
+  g_return_if_fail (vectors == NULL || GIMP_IS_VECTORS (vectors));
+
+  value->data[0].v_int = vectors ? gimp_item_get_ID (GIMP_ITEM (vectors)) : -1;
+}
+
+
+/*
+ * GIMP_TYPE_DISPLAY_ID
+ */
+
+GType
+gimp_display_id_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    {
+      const GTypeInfo info = { 0, };
+
+      type = g_type_register_static (G_TYPE_INT, "GimpDisplayID", &info, 0);
+    }
+
+  return type;
+}
+
+
+/*
+ * GIMP_TYPE_PARAM_DISPLAY_ID
+ */
+
+static void       gimp_param_display_id_class_init  (GParamSpecClass *klass);
+static void       gimp_param_display_id_init        (GParamSpec      *pspec);
+static void       gimp_param_display_id_set_default (GParamSpec      *pspec,
+                                                     GValue          *value);
+static gboolean   gimp_param_display_id_validate    (GParamSpec      *pspec,
+                                                     GValue          *value);
+static gint       gimp_param_display_id_values_cmp  (GParamSpec      *pspec,
+                                                     const GValue    *value1,
+                                                     const GValue    *value2);
+
+GType
+gimp_param_display_id_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    {
+      const GTypeInfo info =
+      {
+        sizeof (GParamSpecClass),
+        NULL, NULL,
+        (GClassInitFunc) gimp_param_display_id_class_init,
+        NULL, NULL,
+        sizeof (GimpParamSpecDisplayID),
+        0,
+        (GInstanceInitFunc) gimp_param_display_id_init
+      };
+
+      type = g_type_register_static (G_TYPE_PARAM_INT,
+                                     "GimpParamDisplayID", &info, 0);
+    }
+
+  return type;
+}
+
+static void
+gimp_param_display_id_class_init (GParamSpecClass *klass)
+{
+  klass->value_type        = GIMP_TYPE_DISPLAY_ID;
+  klass->value_set_default = gimp_param_display_id_set_default;
+  klass->value_validate    = gimp_param_display_id_validate;
+  klass->values_cmp        = gimp_param_display_id_values_cmp;
+}
+
+static void
+gimp_param_display_id_init (GParamSpec *pspec)
+{
+  GimpParamSpecDisplayID *ispec = GIMP_PARAM_SPEC_DISPLAY_ID (pspec);
+
+  ispec->gimp    = NULL;
+  ispec->none_ok = FALSE;
+}
+
+static void
+gimp_param_display_id_set_default (GParamSpec *pspec,
+                                   GValue     *value)
+{
+  value->data[0].v_int = -1;
+}
+
+static gboolean
+gimp_param_display_id_validate (GParamSpec *pspec,
+                                GValue     *value)
+{
+  GimpParamSpecDisplayID *ispec      = GIMP_PARAM_SPEC_DISPLAY_ID (pspec);
+  gint                    display_id = value->data[0].v_int;
+  GimpObject             *display;
+
+  if (ispec->none_ok && (display_id == 0 || display_id == -1))
+    return FALSE;
+
+  display = gimp_get_display_by_ID (ispec->gimp, display_id);
+
+  if (! GIMP_IS_OBJECT (display))
+    {
+      value->data[0].v_int = -1;
+      return TRUE;
+    }
+
+  return FALSE;
+}
+
+static gint
+gimp_param_display_id_values_cmp (GParamSpec   *pspec,
+                                  const GValue *value1,
+                                  const GValue *value2)
+{
+  gint display_id1 = value1->data[0].v_int;
+  gint display_id2 = value2->data[0].v_int;
+
+  /*  try to return at least *something*, it's useless anyway...  */
+
+  if (display_id1 < display_id2)
+    return -1;
+  else if (display_id1 > display_id2)
+    return 1;
+  else
+    return 0;
+}
+
+GParamSpec *
+gimp_param_spec_display_id (const gchar *name,
+                            const gchar *nick,
+                            const gchar *blurb,
+                            Gimp        *gimp,
+                            gboolean     none_ok,
+                            GParamFlags  flags)
+{
+  GimpParamSpecDisplayID *ispec;
+
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  ispec = g_param_spec_internal (GIMP_TYPE_PARAM_DISPLAY_ID,
+                                 name, nick, blurb, flags);
+
+  ispec->gimp    = gimp;
+  ispec->none_ok = none_ok ? TRUE : FALSE;
+
+  return G_PARAM_SPEC (ispec);
+}
+
+GimpObject *
+gimp_value_get_display (const GValue *value,
+                        Gimp         *gimp)
+{
+  g_return_val_if_fail (GIMP_VALUE_HOLDS_DISPLAY_ID (value), NULL);
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  return gimp_get_display_by_ID (gimp, value->data[0].v_int);
+}
+
+void
+gimp_value_set_display (GValue     *value,
+                        GimpObject *display)
+{
+  gint id = -1;
+
+  g_return_if_fail (GIMP_VALUE_HOLDS_DISPLAY_ID (value));
+  g_return_if_fail (display == NULL || GIMP_IS_OBJECT (display));
+
+  if (display)
+    g_object_get (display, "id", &id, NULL);
+
+  value->data[0].v_int = id;
+}
+
+
+/*
+ * GIMP_TYPE_ARRAY
+ */
+
+GimpArray *
+gimp_array_new (const guint8 *data,
+                gsize         length,
+                gboolean      static_data)
+{
+  GimpArray *array;
+
+  g_return_val_if_fail ((data == NULL && length == 0) ||
+                        (data != NULL && length  > 0), NULL);
+
+  array = g_slice_new0 (GimpArray);
+
+  array->data        = static_data ? (guint8 *) data : g_memdup (data, length);
+  array->length      = length;
+  array->static_data = static_data;
+
+  return array;
+}
+
+GimpArray *
+gimp_array_copy (const GimpArray *array)
+{
+  if (array)
+    return gimp_array_new (array->data, array->length, FALSE);
+
+  return NULL;
+}
+
+void
+gimp_array_free (GimpArray *array)
+{
+  if (array)
+    {
+      if (! array->static_data)
+        g_free (array->data);
+
+      g_slice_free (GimpArray, array);
+    }
+}
+
+GType
+gimp_array_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    type = g_boxed_type_register_static ("GimpArray",
+                                         (GBoxedCopyFunc) gimp_array_copy,
+                                         (GBoxedFreeFunc) gimp_array_free);
+
+  return type;
+}
+
+
+/*
+ * GIMP_TYPE_PARAM_ARRAY
+ */
+
+static void       gimp_param_array_class_init  (GParamSpecClass *klass);
+static void       gimp_param_array_init        (GParamSpec      *pspec);
+static gboolean   gimp_param_array_validate    (GParamSpec      *pspec,
+                                                GValue          *value);
+static gint       gimp_param_array_values_cmp  (GParamSpec      *pspec,
+                                                const GValue    *value1,
+                                                const GValue    *value2);
+
+GType
+gimp_param_array_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    {
+      const GTypeInfo info =
+      {
+        sizeof (GParamSpecClass),
+        NULL, NULL,
+        (GClassInitFunc) gimp_param_array_class_init,
+        NULL, NULL,
+        sizeof (GimpParamSpecArray),
+        0,
+        (GInstanceInitFunc) gimp_param_array_init
+      };
+
+      type = g_type_register_static (G_TYPE_PARAM_BOXED,
+                                     "GimpParamArray", &info, 0);
+    }
+
+  return type;
+}
+
+static void
+gimp_param_array_class_init (GParamSpecClass *klass)
+{
+  klass->value_type     = GIMP_TYPE_ARRAY;
+  klass->value_validate = gimp_param_array_validate;
+  klass->values_cmp     = gimp_param_array_values_cmp;
+}
+
+static void
+gimp_param_array_init (GParamSpec *pspec)
+{
+}
+
+static gboolean
+gimp_param_array_validate (GParamSpec *pspec,
+                           GValue     *value)
+{
+  GimpArray *array = value->data[0].v_pointer;
+
+  if (array)
+    {
+      if ((array->data == NULL && array->length != 0) ||
+          (array->data != NULL && array->length == 0))
+        {
+          g_value_set_boxed (value, NULL);
+          return TRUE;
+        }
+    }
+
+  return FALSE;
+}
+
+static gint
+gimp_param_array_values_cmp (GParamSpec   *pspec,
+                             const GValue *value1,
+                             const GValue *value2)
+{
+  GimpArray *array1 = value1->data[0].v_pointer;
+  GimpArray *array2 = value2->data[0].v_pointer;
+
+  /*  try to return at least *something*, it's useless anyway...  */
+
+  if (! array1)
+    return array2 != NULL ? -1 : 0;
+  else if (! array2)
+    return array1 != NULL ? 1 : 0;
+  else if (array1->length < array2->length)
+    return -1;
+  else if (array1->length > array2->length)
+    return 1;
+
+  return 0;
+}
+
+GParamSpec *
+gimp_param_spec_array (const gchar *name,
+                       const gchar *nick,
+                       const gchar *blurb,
+                       GParamFlags  flags)
+{
+  GimpParamSpecArray *array_spec;
+
+  array_spec = g_param_spec_internal (GIMP_TYPE_PARAM_ARRAY,
+                                      name, nick, blurb, flags);
+
+  return G_PARAM_SPEC (array_spec);
+}
+
+static const guint8 *
+gimp_value_get_array (const GValue *value)
+{
+  GimpArray *array = value->data[0].v_pointer;
+
+  if (array)
+    return array->data;
+
+  return NULL;
+}
+
+static guint8 *
+gimp_value_dup_array (const GValue *value)
+{
+  GimpArray *array = value->data[0].v_pointer;
+
+  if (array)
+    return g_memdup (array->data, array->length);
+
+  return NULL;
+}
+
+static void
+gimp_value_set_array (GValue       *value,
+                      const guint8 *data,
+                      gsize         length)
+{
+  GimpArray *array = gimp_array_new (data, length, FALSE);
+
+  g_value_take_boxed (value, array);
+}
+
+static void
+gimp_value_set_static_array (GValue       *value,
+                             const guint8 *data,
+                             gsize         length)
+{
+  GimpArray *array = gimp_array_new (data, length, TRUE);
+
+  g_value_take_boxed (value, array);
+}
+
+static void
+gimp_value_take_array (GValue *value,
+                       guint8 *data,
+                       gsize   length)
+{
+  GimpArray *array = gimp_array_new (data, length, TRUE);
+
+  array->static_data = FALSE;
+
+  g_value_take_boxed (value, array);
+}
+
+
+/*
+ * GIMP_TYPE_INT8_ARRAY
+ */
+
+GType
+gimp_int8_array_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    type = g_boxed_type_register_static ("GimpInt8Array",
+                                         (GBoxedCopyFunc) gimp_array_copy,
+                                         (GBoxedFreeFunc) gimp_array_free);
+
+  return type;
+}
+
+
+/*
+ * GIMP_TYPE_PARAM_INT8_ARRAY
+ */
+
+static void   gimp_param_int8_array_class_init (GParamSpecClass *klass);
+static void   gimp_param_int8_array_init       (GParamSpec      *pspec);
+
+GType
+gimp_param_int8_array_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    {
+      const GTypeInfo info =
+      {
+        sizeof (GParamSpecClass),
+        NULL, NULL,
+        (GClassInitFunc) gimp_param_int8_array_class_init,
+        NULL, NULL,
+        sizeof (GimpParamSpecArray),
+        0,
+        (GInstanceInitFunc) gimp_param_int8_array_init
+      };
+
+      type = g_type_register_static (GIMP_TYPE_PARAM_ARRAY,
+                                     "GimpParamInt8Array", &info, 0);
+    }
+
+  return type;
+}
+
+static void
+gimp_param_int8_array_class_init (GParamSpecClass *klass)
+{
+  klass->value_type = GIMP_TYPE_INT8_ARRAY;
+}
+
+static void
+gimp_param_int8_array_init (GParamSpec *pspec)
+{
+}
+
+GParamSpec *
+gimp_param_spec_int8_array (const gchar *name,
+                            const gchar *nick,
+                            const gchar *blurb,
+                            GParamFlags  flags)
+{
+  GimpParamSpecArray *array_spec;
+
+  array_spec = g_param_spec_internal (GIMP_TYPE_PARAM_INT8_ARRAY,
+                                      name, nick, blurb, flags);
+
+  return G_PARAM_SPEC (array_spec);
+}
+
+const guint8 *
+gimp_value_get_int8array (const GValue *value)
+{
+  g_return_val_if_fail (GIMP_VALUE_HOLDS_INT8_ARRAY (value), NULL);
+
+  return gimp_value_get_array (value);
+}
+
+guint8 *
+gimp_value_dup_int8array (const GValue *value)
+{
+  g_return_val_if_fail (GIMP_VALUE_HOLDS_INT8_ARRAY (value), NULL);
+
+  return gimp_value_dup_array (value);
+}
+
+void
+gimp_value_set_int8array (GValue       *value,
+                          const guint8 *data,
+                          gsize         length)
+{
+  g_return_if_fail (GIMP_VALUE_HOLDS_INT8_ARRAY (value));
+
+  gimp_value_set_array (value, data, length);
+}
+
+void
+gimp_value_set_static_int8array (GValue       *value,
+                                 const guint8 *data,
+                                 gsize         length)
+{
+  g_return_if_fail (GIMP_VALUE_HOLDS_INT8_ARRAY (value));
+
+  gimp_value_set_static_array (value, data, length);
+}
+
+void
+gimp_value_take_int8array (GValue *value,
+                           guint8 *data,
+                           gsize   length)
+{
+  g_return_if_fail (GIMP_VALUE_HOLDS_INT8_ARRAY (value));
+
+  gimp_value_take_array (value, data, length);
+}
+
+
+/*
+ * GIMP_TYPE_INT16_ARRAY
+ */
+
+GType
+gimp_int16_array_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    type = g_boxed_type_register_static ("GimpInt16Array",
+                                         (GBoxedCopyFunc) gimp_array_copy,
+                                         (GBoxedFreeFunc) gimp_array_free);
+
+  return type;
+}
+
+
+/*
+ * GIMP_TYPE_PARAM_INT16_ARRAY
+ */
+
+static void   gimp_param_int16_array_class_init (GParamSpecClass *klass);
+static void   gimp_param_int16_array_init       (GParamSpec      *pspec);
+
+GType
+gimp_param_int16_array_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    {
+      const GTypeInfo info =
+      {
+        sizeof (GParamSpecClass),
+        NULL, NULL,
+        (GClassInitFunc) gimp_param_int16_array_class_init,
+        NULL, NULL,
+        sizeof (GimpParamSpecArray),
+        0,
+        (GInstanceInitFunc) gimp_param_int16_array_init
+      };
+
+      type = g_type_register_static (GIMP_TYPE_PARAM_ARRAY,
+                                     "GimpParamInt16Array", &info, 0);
+    }
+
+  return type;
+}
+
+static void
+gimp_param_int16_array_class_init (GParamSpecClass *klass)
+{
+  klass->value_type = GIMP_TYPE_INT16_ARRAY;
+}
+
+static void
+gimp_param_int16_array_init (GParamSpec *pspec)
+{
+}
+
+GParamSpec *
+gimp_param_spec_int16_array (const gchar *name,
+                             const gchar *nick,
+                             const gchar *blurb,
+                             GParamFlags  flags)
+{
+  GimpParamSpecArray *array_spec;
+
+  array_spec = g_param_spec_internal (GIMP_TYPE_PARAM_INT16_ARRAY,
+                                      name, nick, blurb, flags);
+
+  return G_PARAM_SPEC (array_spec);
+}
+
+const gint16 *
+gimp_value_get_int16array (const GValue *value)
+{
+  g_return_val_if_fail (GIMP_VALUE_HOLDS_INT16_ARRAY (value), NULL);
+
+  return (const gint16 *) gimp_value_get_array (value);
+}
+
+gint16 *
+gimp_value_dup_int16array (const GValue *value)
+{
+  g_return_val_if_fail (GIMP_VALUE_HOLDS_INT16_ARRAY (value), NULL);
+
+  return (gint16 *) gimp_value_dup_array (value);
+}
+
+void
+gimp_value_set_int16array (GValue       *value,
+                           const gint16 *data,
+                           gsize         length)
+{
+  g_return_if_fail (GIMP_VALUE_HOLDS_INT16_ARRAY (value));
+
+  gimp_value_set_array (value, (const guint8 *) data,
+                        length * sizeof (gint16));
+}
+
+void
+gimp_value_set_static_int16array (GValue       *value,
+                                  const gint16 *data,
+                                  gsize         length)
+{
+  g_return_if_fail (GIMP_VALUE_HOLDS_INT16_ARRAY (value));
+
+  gimp_value_set_static_array (value, (const guint8 *) data,
+                               length * sizeof (gint16));
+}
+
+void
+gimp_value_take_int16array (GValue *value,
+                            gint16 *data,
+                            gsize   length)
+{
+  g_return_if_fail (GIMP_VALUE_HOLDS_INT16_ARRAY (value));
+
+  gimp_value_take_array (value, (guint8 *) data,
+                         length * sizeof (gint16));
+}
+
+
+/*
+ * GIMP_TYPE_INT32_ARRAY
+ */
+
+GType
+gimp_int32_array_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    type = g_boxed_type_register_static ("GimpInt32Array",
+                                         (GBoxedCopyFunc) gimp_array_copy,
+                                         (GBoxedFreeFunc) gimp_array_free);
+
+  return type;
+}
+
+
+/*
+ * GIMP_TYPE_PARAM_INT32_ARRAY
+ */
+
+static void   gimp_param_int32_array_class_init (GParamSpecClass *klass);
+static void   gimp_param_int32_array_init       (GParamSpec      *pspec);
+
+GType
+gimp_param_int32_array_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    {
+      const GTypeInfo info =
+      {
+        sizeof (GParamSpecClass),
+        NULL, NULL,
+        (GClassInitFunc) gimp_param_int32_array_class_init,
+        NULL, NULL,
+        sizeof (GimpParamSpecArray),
+        0,
+        (GInstanceInitFunc) gimp_param_int32_array_init
+      };
+
+      type = g_type_register_static (GIMP_TYPE_PARAM_ARRAY,
+                                     "GimpParamInt32Array", &info, 0);
+    }
+
+  return type;
+}
+
+static void
+gimp_param_int32_array_class_init (GParamSpecClass *klass)
+{
+  klass->value_type = GIMP_TYPE_INT32_ARRAY;
+}
+
+static void
+gimp_param_int32_array_init (GParamSpec *pspec)
+{
+}
+
+GParamSpec *
+gimp_param_spec_int32_array (const gchar *name,
+                             const gchar *nick,
+                             const gchar *blurb,
+                             GParamFlags  flags)
+{
+  GimpParamSpecArray *array_spec;
+
+  array_spec = g_param_spec_internal (GIMP_TYPE_PARAM_INT32_ARRAY,
+                                      name, nick, blurb, flags);
+
+  return G_PARAM_SPEC (array_spec);
+}
+
+const gint32 *
+gimp_value_get_int32array (const GValue *value)
+{
+  g_return_val_if_fail (GIMP_VALUE_HOLDS_INT32_ARRAY (value), NULL);
+
+  return (const gint32 *) gimp_value_get_array (value);
+}
+
+gint32 *
+gimp_value_dup_int32array (const GValue *value)
+{
+  g_return_val_if_fail (GIMP_VALUE_HOLDS_INT32_ARRAY (value), NULL);
+
+  return (gint32 *) gimp_value_dup_array (value);
+}
+
+void
+gimp_value_set_int32array (GValue       *value,
+                           const gint32 *data,
+                           gsize         length)
+{
+  g_return_if_fail (GIMP_VALUE_HOLDS_INT32_ARRAY (value));
+
+  gimp_value_set_array (value, (const guint8 *) data,
+                        length * sizeof (gint32));
+}
+
+void
+gimp_value_set_static_int32array (GValue       *value,
+                                  const gint32 *data,
+                                  gsize         length)
+{
+  g_return_if_fail (GIMP_VALUE_HOLDS_INT32_ARRAY (value));
+
+  gimp_value_set_static_array (value, (const guint8 *) data,
+                               length * sizeof (gint32));
+}
+
+void
+gimp_value_take_int32array (GValue *value,
+                            gint32 *data,
+                            gsize   length)
+{
+  g_return_if_fail (GIMP_VALUE_HOLDS_INT32_ARRAY (value));
+
+  gimp_value_take_array (value, (guint8 *) data,
+                         length * sizeof (gint32));
+}
+
+
+/*
+ * GIMP_TYPE_FLOAT_ARRAY
+ */
+
+GType
+gimp_float_array_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    type = g_boxed_type_register_static ("GimpFloatArray",
+                                         (GBoxedCopyFunc) gimp_array_copy,
+                                         (GBoxedFreeFunc) gimp_array_free);
+
+  return type;
+}
+
+
+/*
+ * GIMP_TYPE_PARAM_FLOAT_ARRAY
+ */
+
+static void   gimp_param_float_array_class_init (GParamSpecClass *klass);
+static void   gimp_param_float_array_init       (GParamSpec      *pspec);
+
+GType
+gimp_param_float_array_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    {
+      const GTypeInfo info =
+      {
+        sizeof (GParamSpecClass),
+        NULL, NULL,
+        (GClassInitFunc) gimp_param_float_array_class_init,
+        NULL, NULL,
+        sizeof (GimpParamSpecArray),
+        0,
+        (GInstanceInitFunc) gimp_param_float_array_init
+      };
+
+      type = g_type_register_static (GIMP_TYPE_PARAM_ARRAY,
+                                     "GimpParamFloatArray", &info, 0);
+    }
+
+  return type;
+}
+
+static void
+gimp_param_float_array_class_init (GParamSpecClass *klass)
+{
+  klass->value_type = GIMP_TYPE_FLOAT_ARRAY;
+}
+
+static void
+gimp_param_float_array_init (GParamSpec *pspec)
+{
+}
+
+GParamSpec *
+gimp_param_spec_float_array (const gchar *name,
+                             const gchar *nick,
+                             const gchar *blurb,
+                             GParamFlags  flags)
+{
+  GimpParamSpecArray *array_spec;
+
+  array_spec = g_param_spec_internal (GIMP_TYPE_PARAM_FLOAT_ARRAY,
+                                      name, nick, blurb, flags);
+
+  return G_PARAM_SPEC (array_spec);
+}
+
+const gdouble *
+gimp_value_get_floatarray (const GValue *value)
+{
+  g_return_val_if_fail (GIMP_VALUE_HOLDS_FLOAT_ARRAY (value), NULL);
+
+  return (const gdouble *) gimp_value_get_array (value);
+}
+
+gdouble *
+gimp_value_dup_floatarray (const GValue *value)
+{
+  g_return_val_if_fail (GIMP_VALUE_HOLDS_FLOAT_ARRAY (value), NULL);
+
+  return (gdouble *) gimp_value_dup_array (value);
+}
+
+void
+gimp_value_set_floatarray (GValue        *value,
+                           const gdouble *data,
+                           gsize         length)
+{
+  g_return_if_fail (GIMP_VALUE_HOLDS_FLOAT_ARRAY (value));
+
+  gimp_value_set_array (value, (const guint8 *) data,
+                        length * sizeof (gdouble));
+}
+
+void
+gimp_value_set_static_floatarray (GValue        *value,
+                                  const gdouble *data,
+                                  gsize         length)
+{
+  g_return_if_fail (GIMP_VALUE_HOLDS_FLOAT_ARRAY (value));
+
+  gimp_value_set_static_array (value, (const guint8 *) data,
+                               length * sizeof (gdouble));
+}
+
+void
+gimp_value_take_floatarray (GValue  *value,
+                            gdouble *data,
+                            gsize    length)
+{
+  g_return_if_fail (GIMP_VALUE_HOLDS_FLOAT_ARRAY (value));
+
+  gimp_value_take_array (value, (guint8 *) data,
+                         length * sizeof (gdouble));
+}
+
+
+/*
+ * GIMP_TYPE_STRING_ARRAY
+ */
+
+GimpArray *
+gimp_string_array_new (const gchar **data,
+                       gsize         length,
+                       gboolean      static_data)
+{
+  GimpArray *array;
+
+  g_return_val_if_fail ((data == NULL && length == 0) ||
+                        (data != NULL && length  > 0), NULL);
+
+  array = g_slice_new0 (GimpArray);
+
+  if (! static_data)
+    {
+      gchar **tmp = g_new (gchar *, length);
+      gint    i;
+
+      for (i = 0; i < length; i++)
+        tmp[i] = g_strdup (data[i]);
+
+      array->data = (guint8 *) tmp;
+    }
+  else
+    {
+      array->data = (guint8 *) data;
+    }
+
+  array->length      = length;
+  array->static_data = static_data;
+
+  return array;
+}
+
+GimpArray *
+gimp_string_array_copy (const GimpArray *array)
+{
+  if (array)
+    return gimp_string_array_new ((const gchar **) array->data,
+                                  array->length, FALSE);
+
+  return NULL;
+}
+
+void
+gimp_string_array_free (GimpArray *array)
+{
+  if (array)
+    {
+      if (! array->static_data)
+        {
+          gchar **tmp = (gchar **) array->data;
+          gint    i;
+
+          for (i = 0; i < array->length; i++)
+            g_free (tmp[i]);
+
+          g_free (array->data);
+        }
+
+      g_slice_free (GimpArray, array);
+    }
+}
+
+GType
+gimp_string_array_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    type = g_boxed_type_register_static ("GimpStringArray",
+                                         (GBoxedCopyFunc) gimp_string_array_copy,
+                                         (GBoxedFreeFunc) gimp_string_array_free);
+
+  return type;
+}
+
+
+/*
+ * GIMP_TYPE_PARAM_STRING_ARRAY
+ */
+
+static void       gimp_param_string_array_class_init  (GParamSpecClass *klass);
+static void       gimp_param_string_array_init        (GParamSpec      *pspec);
+static gboolean   gimp_param_string_array_validate    (GParamSpec      *pspec,
+                                                       GValue          *value);
+static gint       gimp_param_string_array_values_cmp  (GParamSpec      *pspec,
+                                                       const GValue    *value1,
+                                                       const GValue    *value2);
+
+GType
+gimp_param_string_array_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    {
+      const GTypeInfo info =
+      {
+        sizeof (GParamSpecClass),
+        NULL, NULL,
+        (GClassInitFunc) gimp_param_string_array_class_init,
+        NULL, NULL,
+        sizeof (GimpParamSpecArray),
+        0,
+        (GInstanceInitFunc) gimp_param_string_array_init
+      };
+
+      type = g_type_register_static (G_TYPE_PARAM_BOXED,
+                                     "GimpParamStringArray", &info, 0);
+    }
+
+  return type;
+}
+
+static void
+gimp_param_string_array_class_init (GParamSpecClass *klass)
+{
+  klass->value_type     = GIMP_TYPE_STRING_ARRAY;
+  klass->value_validate = gimp_param_string_array_validate;
+  klass->values_cmp     = gimp_param_string_array_values_cmp;
+}
+
+static void
+gimp_param_string_array_init (GParamSpec *pspec)
+{
+}
+
+static gboolean
+gimp_param_string_array_validate (GParamSpec *pspec,
+                                  GValue     *value)
+{
+  GimpArray *array = value->data[0].v_pointer;
+
+  if (array)
+    {
+      if ((array->data == NULL && array->length != 0) ||
+          (array->data != NULL && array->length == 0))
+        {
+          g_value_set_boxed (value, NULL);
+          return TRUE;
+        }
+    }
+
+  return FALSE;
+}
+
+static gint
+gimp_param_string_array_values_cmp (GParamSpec   *pspec,
+                                    const GValue *value1,
+                                    const GValue *value2)
+{
+  GimpArray *array1 = value1->data[0].v_pointer;
+  GimpArray *array2 = value2->data[0].v_pointer;
+
+  /*  try to return at least *something*, it's useless anyway...  */
+
+  if (! array1)
+    return array2 != NULL ? -1 : 0;
+  else if (! array2)
+    return array1 != NULL ? 1 : 0;
+  else if (array1->length < array2->length)
+    return -1;
+  else if (array1->length > array2->length)
+    return 1;
+
+  return 0;
+}
+
+GParamSpec *
+gimp_param_spec_string_array (const gchar *name,
+                              const gchar *nick,
+                              const gchar *blurb,
+                              GParamFlags  flags)
+{
+  GimpParamSpecStringArray *array_spec;
+
+  array_spec = g_param_spec_internal (GIMP_TYPE_PARAM_STRING_ARRAY,
+                                      name, nick, blurb, flags);
+
+  return G_PARAM_SPEC (array_spec);
+}
+
+const gchar **
+gimp_value_get_stringarray (const GValue *value)
+{
+  GimpArray *array;
+
+  g_return_val_if_fail (GIMP_VALUE_HOLDS_STRING_ARRAY (value), NULL);
+
+  array = value->data[0].v_pointer;
+
+  if (array)
+    return (const gchar **) array->data;
+
+  return NULL;
+}
+
+gchar **
+gimp_value_dup_stringarray (const GValue *value)
+{
+  GimpArray *array;
+
+  g_return_val_if_fail (GIMP_VALUE_HOLDS_STRING_ARRAY (value), NULL);
+
+  array = value->data[0].v_pointer;
+
+  if (array)
+    {
+      gchar **ret = g_memdup (array->data, array->length * sizeof (gchar *));
+      gint    i;
+
+      for (i = 0; i < array->length; i++)
+        ret[i] = g_strdup (ret[i]);
+
+      return ret;
+    }
+
+  return NULL;
+}
+
+void
+gimp_value_set_stringarray (GValue       *value,
+                            const gchar **data,
+                            gsize         length)
+{
+  GimpArray *array;
+
+  g_return_if_fail (GIMP_VALUE_HOLDS_STRING_ARRAY (value));
+
+  array = gimp_string_array_new (data, length, FALSE);
+
+  g_value_take_boxed (value, array);
+}
+
+void
+gimp_value_set_static_stringarray (GValue       *value,
+                                   const gchar **data,
+                                   gsize         length)
+{
+  GimpArray *array;
+
+  g_return_if_fail (GIMP_VALUE_HOLDS_STRING_ARRAY (value));
+
+  array = gimp_string_array_new (data, length, TRUE);
+
+  g_value_take_boxed (value, array);
+}
+
+void
+gimp_value_take_stringarray (GValue  *value,
+                             gchar  **data,
+                             gsize    length)
+{
+  GimpArray *array;
+
+  g_return_if_fail (GIMP_VALUE_HOLDS_STRING_ARRAY (value));
+
+  array = gimp_string_array_new ((const gchar **) data, length, TRUE);
+  array->static_data = FALSE;
+
+  g_value_take_boxed (value, array);
+}
+
+
+/*
+ * GIMP_TYPE_COLOR_ARRAY
+ */
+
+GType
+gimp_color_array_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    type = g_boxed_type_register_static ("GimpColorArray",
+                                         (GBoxedCopyFunc) gimp_array_copy,
+                                         (GBoxedFreeFunc) gimp_array_free);
+
+  return type;
+}
+
+
+/*
+ * GIMP_TYPE_PARAM_COLOR_ARRAY
+ */
+
+static void  gimp_param_color_array_class_init (GParamSpecClass *klass);
+static void  gimp_param_color_array_init       (GParamSpec      *pspec);
+
+GType
+gimp_param_color_array_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    {
+      const GTypeInfo info =
+      {
+        sizeof (GParamSpecClass),
+        NULL, NULL,
+        (GClassInitFunc) gimp_param_color_array_class_init,
+        NULL, NULL,
+        sizeof (GimpParamSpecArray),
+        0,
+        (GInstanceInitFunc) gimp_param_color_array_init
+      };
+
+      type = g_type_register_static (G_TYPE_PARAM_BOXED,
+                                     "GimpParamColorArray", &info, 0);
+    }
+
+  return type;
+}
+
+static void
+gimp_param_color_array_class_init (GParamSpecClass *klass)
+{
+  klass->value_type = GIMP_TYPE_COLOR_ARRAY;
+}
+
+static void
+gimp_param_color_array_init (GParamSpec *pspec)
+{
+}
+
+GParamSpec *
+gimp_param_spec_color_array (const gchar *name,
+                             const gchar *nick,
+                             const gchar *blurb,
+                             GParamFlags  flags)
+{
+  GimpParamSpecColorArray *array_spec;
+
+  array_spec = g_param_spec_internal (GIMP_TYPE_PARAM_COLOR_ARRAY,
+                                      name, nick, blurb, flags);
+
+  return G_PARAM_SPEC (array_spec);
+}
+
+const GimpRGB *
+gimp_value_get_colorarray (const GValue *value)
+{
+  g_return_val_if_fail (GIMP_VALUE_HOLDS_COLOR_ARRAY (value), NULL);
+
+  return (const GimpRGB *) gimp_value_get_array (value);
+}
+
+GimpRGB *
+gimp_value_dup_colorarray (const GValue *value)
+{
+  g_return_val_if_fail (GIMP_VALUE_HOLDS_COLOR_ARRAY (value), NULL);
+
+  return (GimpRGB *) gimp_value_dup_array (value);
+}
+
+void
+gimp_value_set_colorarray (GValue        *value,
+                           const GimpRGB *data,
+                           gsize         length)
+{
+  g_return_if_fail (GIMP_VALUE_HOLDS_COLOR_ARRAY (value));
+
+  gimp_value_set_array (value, (const guint8 *) data,
+                        length * sizeof (GimpRGB));
+}
+
+void
+gimp_value_set_static_colorarray (GValue        *value,
+                                  const GimpRGB *data,
+                                  gsize          length)
+{
+  g_return_if_fail (GIMP_VALUE_HOLDS_COLOR_ARRAY (value));
+
+  gimp_value_set_static_array (value, (const guint8 *) data,
+                               length * sizeof (GimpRGB));
+}
+
+void
+gimp_value_take_colorarray (GValue  *value,
+                            GimpRGB *data,
+                            gsize    length)
+{
+  g_return_if_fail (GIMP_VALUE_HOLDS_COLOR_ARRAY (value));
+
+  gimp_value_take_array (value, (guint8 *) data,
+                         length * sizeof (GimpRGB));
+}
diff --git a/app/core/gimpparamspecs.h b/app/core/gimpparamspecs.h
new file mode 100644
index 0000000..abfb56f
--- /dev/null
+++ b/app/core/gimpparamspecs.h
@@ -0,0 +1,904 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_PARAM_SPECS_H__
+#define __GIMP_PARAM_SPECS_H__
+
+
+/*
+ * Keep in sync with libgimpconfig/gimpconfig-params.h
+ */
+#define GIMP_PARAM_NO_VALIDATE (1 << (6 + G_PARAM_USER_SHIFT))
+
+
+/*
+ * GIMP_TYPE_INT32
+ */
+
+#define GIMP_TYPE_INT32               (gimp_int32_get_type ())
+#define GIMP_VALUE_HOLDS_INT32(value) (G_TYPE_CHECK_VALUE_TYPE ((value),\
+                                       GIMP_TYPE_INT32))
+
+GType   gimp_int32_get_type           (void) G_GNUC_CONST;
+
+
+/*
+ * GIMP_TYPE_PARAM_INT32
+ */
+
+#define GIMP_TYPE_PARAM_INT32           (gimp_param_int32_get_type ())
+#define GIMP_PARAM_SPEC_INT32(pspec)    (G_TYPE_CHECK_INSTANCE_CAST ((pspec), GIMP_TYPE_PARAM_INT32, GimpParamSpecInt32))
+#define GIMP_IS_PARAM_SPEC_INT32(pspec) (G_TYPE_CHECK_INSTANCE_TYPE ((pspec), GIMP_TYPE_PARAM_INT32))
+
+typedef struct _GimpParamSpecInt32 GimpParamSpecInt32;
+
+struct _GimpParamSpecInt32
+{
+  GParamSpecInt parent_instance;
+};
+
+GType        gimp_param_int32_get_type (void) G_GNUC_CONST;
+
+GParamSpec * gimp_param_spec_int32     (const gchar *name,
+                                        const gchar *nick,
+                                        const gchar *blurb,
+                                        gint         minimum,
+                                        gint         maximum,
+                                        gint         default_value,
+                                        GParamFlags  flags);
+
+
+/*
+ * GIMP_TYPE_INT16
+ */
+
+#define GIMP_TYPE_INT16               (gimp_int16_get_type ())
+#define GIMP_VALUE_HOLDS_INT16(value) (G_TYPE_CHECK_VALUE_TYPE ((value),\
+                                       GIMP_TYPE_INT16))
+
+GType   gimp_int16_get_type           (void) G_GNUC_CONST;
+
+
+/*
+ * GIMP_TYPE_PARAM_INT16
+ */
+
+#define GIMP_TYPE_PARAM_INT16           (gimp_param_int16_get_type ())
+#define GIMP_PARAM_SPEC_INT16(pspec)    (G_TYPE_CHECK_INSTANCE_CAST ((pspec), GIMP_TYPE_PARAM_INT16, GimpParamSpecInt16))
+#define GIMP_IS_PARAM_SPEC_INT16(pspec) (G_TYPE_CHECK_INSTANCE_TYPE ((pspec), GIMP_TYPE_PARAM_INT16))
+
+typedef struct _GimpParamSpecInt16 GimpParamSpecInt16;
+
+struct _GimpParamSpecInt16
+{
+  GParamSpecInt parent_instance;
+};
+
+GType        gimp_param_int16_get_type (void) G_GNUC_CONST;
+
+GParamSpec * gimp_param_spec_int16     (const gchar *name,
+                                        const gchar *nick,
+                                        const gchar *blurb,
+                                        gint         minimum,
+                                        gint         maximum,
+                                        gint         default_value,
+                                        GParamFlags  flags);
+
+
+/*
+ * GIMP_TYPE_INT8
+ */
+
+#define GIMP_TYPE_INT8               (gimp_int8_get_type ())
+#define GIMP_VALUE_HOLDS_INT8(value) (G_TYPE_CHECK_VALUE_TYPE ((value),\
+                                      GIMP_TYPE_INT8))
+
+GType   gimp_int8_get_type           (void) G_GNUC_CONST;
+
+
+/*
+ * GIMP_TYPE_PARAM_INT8
+ */
+
+#define GIMP_TYPE_PARAM_INT8           (gimp_param_int8_get_type ())
+#define GIMP_PARAM_SPEC_INT8(pspec)    (G_TYPE_CHECK_INSTANCE_CAST ((pspec), GIMP_TYPE_PARAM_INT8, GimpParamSpecInt8))
+#define GIMP_IS_PARAM_SPEC_INT8(pspec) (G_TYPE_CHECK_INSTANCE_TYPE ((pspec), GIMP_TYPE_PARAM_INT8))
+
+typedef struct _GimpParamSpecInt8 GimpParamSpecInt8;
+
+struct _GimpParamSpecInt8
+{
+  GParamSpecUInt parent_instance;
+};
+
+GType        gimp_param_int8_get_type (void) G_GNUC_CONST;
+
+GParamSpec * gimp_param_spec_int8     (const gchar *name,
+                                       const gchar *nick,
+                                       const gchar *blurb,
+                                       guint        minimum,
+                                       guint        maximum,
+                                       guint        default_value,
+                                       GParamFlags  flags);
+
+
+/*
+ * GIMP_TYPE_PARAM_STRING
+ */
+
+#define GIMP_TYPE_PARAM_STRING           (gimp_param_string_get_type ())
+#define GIMP_PARAM_SPEC_STRING(pspec)    (G_TYPE_CHECK_INSTANCE_CAST ((pspec), GIMP_TYPE_PARAM_STRING, GimpParamSpecString))
+#define GIMP_IS_PARAM_SPEC_STRING(pspec) (G_TYPE_CHECK_INSTANCE_TYPE ((pspec), GIMP_TYPE_PARAM_STRING))
+
+typedef struct _GimpParamSpecString GimpParamSpecString;
+
+struct _GimpParamSpecString
+{
+  GParamSpecString parent_instance;
+
+  guint            allow_non_utf8 : 1;
+  guint            non_empty      : 1;
+};
+
+GType        gimp_param_string_get_type (void) G_GNUC_CONST;
+
+GParamSpec * gimp_param_spec_string     (const gchar *name,
+                                         const gchar *nick,
+                                         const gchar *blurb,
+                                         gboolean     allow_non_utf8,
+                                         gboolean     null_ok,
+                                         gboolean     non_empty,
+                                         const gchar *default_value,
+                                         GParamFlags  flags);
+
+
+/*
+ * GIMP_TYPE_PARAM_ENUM
+ */
+
+#define GIMP_TYPE_PARAM_ENUM           (gimp_param_enum_get_type ())
+#define GIMP_PARAM_SPEC_ENUM(pspec)    (G_TYPE_CHECK_INSTANCE_CAST ((pspec), GIMP_TYPE_PARAM_ENUM, GimpParamSpecEnum))
+
+#define GIMP_IS_PARAM_SPEC_ENUM(pspec) (G_TYPE_CHECK_INSTANCE_TYPE ((pspec), GIMP_TYPE_PARAM_ENUM))
+
+typedef struct _GimpParamSpecEnum GimpParamSpecEnum;
+
+struct _GimpParamSpecEnum
+{
+  GParamSpecEnum  parent_instance;
+
+  GSList         *excluded_values;
+};
+
+GType        gimp_param_enum_get_type     (void) G_GNUC_CONST;
+
+GParamSpec * gimp_param_spec_enum         (const gchar       *name,
+                                           const gchar       *nick,
+                                           const gchar       *blurb,
+                                           GType              enum_type,
+                                           gint               default_value,
+                                           GParamFlags        flags);
+
+void   gimp_param_spec_enum_exclude_value (GimpParamSpecEnum *espec,
+                                           gint               value);
+
+
+/*
+ * GIMP_TYPE_IMAGE_ID
+ */
+
+#define GIMP_TYPE_IMAGE_ID               (gimp_image_id_get_type ())
+#define GIMP_VALUE_HOLDS_IMAGE_ID(value) (G_TYPE_CHECK_VALUE_TYPE ((value),\
+                                          GIMP_TYPE_IMAGE_ID))
+
+GType   gimp_image_id_get_type           (void) G_GNUC_CONST;
+
+
+/*
+ * GIMP_TYPE_PARAM_IMAGE_ID
+ */
+
+#define GIMP_TYPE_PARAM_IMAGE_ID           (gimp_param_image_id_get_type ())
+#define GIMP_PARAM_SPEC_IMAGE_ID(pspec)    (G_TYPE_CHECK_INSTANCE_CAST ((pspec), GIMP_TYPE_PARAM_IMAGE_ID, GimpParamSpecImageID))
+#define GIMP_IS_PARAM_SPEC_IMAGE_ID(pspec) (G_TYPE_CHECK_INSTANCE_TYPE ((pspec), GIMP_TYPE_PARAM_IMAGE_ID))
+
+typedef struct _GimpParamSpecImageID GimpParamSpecImageID;
+
+struct _GimpParamSpecImageID
+{
+  GParamSpecInt  parent_instance;
+
+  Gimp          *gimp;
+  gboolean       none_ok;
+};
+
+GType        gimp_param_image_id_get_type (void) G_GNUC_CONST;
+
+GParamSpec * gimp_param_spec_image_id     (const gchar  *name,
+                                           const gchar  *nick,
+                                           const gchar  *blurb,
+                                           Gimp         *gimp,
+                                           gboolean      none_ok,
+                                           GParamFlags   flags);
+
+GimpImage  * gimp_value_get_image         (const GValue *value,
+                                           Gimp         *gimp);
+void         gimp_value_set_image         (GValue       *value,
+                                           GimpImage    *image);
+
+
+
+/*
+ * GIMP_TYPE_ITEM_ID
+ */
+
+#define GIMP_TYPE_ITEM_ID               (gimp_item_id_get_type ())
+#define GIMP_VALUE_HOLDS_ITEM_ID(value) (G_TYPE_CHECK_VALUE_TYPE ((value),\
+                                         GIMP_TYPE_ITEM_ID))
+
+GType   gimp_item_id_get_type           (void) G_GNUC_CONST;
+
+
+/*
+ * GIMP_TYPE_PARAM_ITEM_ID
+ */
+
+#define GIMP_TYPE_PARAM_ITEM_ID           (gimp_param_item_id_get_type ())
+#define GIMP_PARAM_SPEC_ITEM_ID(pspec)    (G_TYPE_CHECK_INSTANCE_CAST ((pspec), GIMP_TYPE_PARAM_ITEM_ID, GimpParamSpecItemID))
+#define GIMP_IS_PARAM_SPEC_ITEM_ID(pspec) (G_TYPE_CHECK_INSTANCE_TYPE ((pspec), GIMP_TYPE_PARAM_ITEM_ID))
+
+typedef struct _GimpParamSpecItemID GimpParamSpecItemID;
+
+struct _GimpParamSpecItemID
+{
+  GParamSpecInt  parent_instance;
+
+  Gimp          *gimp;
+  GType          item_type;
+  gboolean       none_ok;
+};
+
+GType        gimp_param_item_id_get_type (void) G_GNUC_CONST;
+
+GParamSpec * gimp_param_spec_item_id     (const gchar  *name,
+                                          const gchar  *nick,
+                                          const gchar  *blurb,
+                                          Gimp         *gimp,
+                                          gboolean      none_ok,
+                                          GParamFlags   flags);
+
+GimpItem   * gimp_value_get_item         (const GValue *value,
+                                          Gimp         *gimp);
+void         gimp_value_set_item         (GValue       *value,
+                                          GimpItem     *item);
+
+
+/*
+ * GIMP_TYPE_DRAWABLE_ID
+ */
+
+#define GIMP_TYPE_DRAWABLE_ID               (gimp_drawable_id_get_type ())
+#define GIMP_VALUE_HOLDS_DRAWABLE_ID(value) (G_TYPE_CHECK_VALUE_TYPE ((value),\
+                                             GIMP_TYPE_DRAWABLE_ID))
+
+GType   gimp_drawable_id_get_type           (void) G_GNUC_CONST;
+
+
+/*
+ * GIMP_TYPE_PARAM_DRAWABLE_ID
+ */
+
+#define GIMP_TYPE_PARAM_DRAWABLE_ID           (gimp_param_drawable_id_get_type ())
+#define GIMP_PARAM_SPEC_DRAWABLE_ID(pspec)    (G_TYPE_CHECK_INSTANCE_CAST ((pspec), GIMP_TYPE_PARAM_DRAWABLE_ID, GimpParamSpecDrawableID))
+#define GIMP_IS_PARAM_SPEC_DRAWABLE_ID(pspec) (G_TYPE_CHECK_INSTANCE_TYPE ((pspec), GIMP_TYPE_PARAM_DRAWABLE_ID))
+
+typedef struct _GimpParamSpecDrawableID GimpParamSpecDrawableID;
+
+struct _GimpParamSpecDrawableID
+{
+  GimpParamSpecItemID parent_instance;
+};
+
+GType         gimp_param_drawable_id_get_type (void) G_GNUC_CONST;
+
+GParamSpec  * gimp_param_spec_drawable_id     (const gchar  *name,
+                                               const gchar  *nick,
+                                               const gchar  *blurb,
+                                               Gimp         *gimp,
+                                               gboolean      none_ok,
+                                               GParamFlags   flags);
+
+GimpDrawable * gimp_value_get_drawable        (const GValue *value,
+                                               Gimp         *gimp);
+void           gimp_value_set_drawable        (GValue       *value,
+                                               GimpDrawable *drawable);
+
+
+/*
+ * GIMP_TYPE_LAYER_ID
+ */
+
+#define GIMP_TYPE_LAYER_ID               (gimp_layer_id_get_type ())
+#define GIMP_VALUE_HOLDS_LAYER_ID(value) (G_TYPE_CHECK_VALUE_TYPE ((value),\
+                                          GIMP_TYPE_LAYER_ID))
+
+GType   gimp_layer_id_get_type           (void) G_GNUC_CONST;
+
+
+/*
+ * GIMP_TYPE_PARAM_LAYER_ID
+ */
+
+#define GIMP_TYPE_PARAM_LAYER_ID           (gimp_param_layer_id_get_type ())
+#define GIMP_PARAM_SPEC_LAYER_ID(pspec)    (G_TYPE_CHECK_INSTANCE_CAST ((pspec), GIMP_TYPE_PARAM_LAYER_ID, GimpParamSpecLayerID))
+#define GIMP_IS_PARAM_SPEC_LAYER_ID(pspec) (G_TYPE_CHECK_INSTANCE_TYPE ((pspec), GIMP_TYPE_PARAM_LAYER_ID))
+
+typedef struct _GimpParamSpecLayerID GimpParamSpecLayerID;
+
+struct _GimpParamSpecLayerID
+{
+  GimpParamSpecDrawableID parent_instance;
+};
+
+GType        gimp_param_layer_id_get_type (void) G_GNUC_CONST;
+
+GParamSpec * gimp_param_spec_layer_id     (const gchar  *name,
+                                           const gchar  *nick,
+                                           const gchar  *blurb,
+                                           Gimp         *gimp,
+                                           gboolean      none_ok,
+                                           GParamFlags   flags);
+
+GimpLayer  * gimp_value_get_layer         (const GValue *value,
+                                           Gimp         *gimp);
+void         gimp_value_set_layer         (GValue       *value,
+                                           GimpLayer    *layer);
+
+
+/*
+ * GIMP_TYPE_CHANNEL_ID
+ */
+
+#define GIMP_TYPE_CHANNEL_ID               (gimp_channel_id_get_type ())
+#define GIMP_VALUE_HOLDS_CHANNEL_ID(value) (G_TYPE_CHECK_VALUE_TYPE ((value),\
+                                            GIMP_TYPE_CHANNEL_ID))
+
+GType   gimp_channel_id_get_type           (void) G_GNUC_CONST;
+
+
+/*
+ * GIMP_TYPE_PARAM_CHANNEL_ID
+ */
+
+#define GIMP_TYPE_PARAM_CHANNEL_ID           (gimp_param_channel_id_get_type ())
+#define GIMP_PARAM_SPEC_CHANNEL_ID(pspec)    (G_TYPE_CHECK_INSTANCE_CAST ((pspec), GIMP_TYPE_PARAM_CHANNEL_ID, GimpParamSpecChannelID))
+#define GIMP_IS_PARAM_SPEC_CHANNEL_ID(pspec) (G_TYPE_CHECK_INSTANCE_TYPE ((pspec), GIMP_TYPE_PARAM_CHANNEL_ID))
+
+typedef struct _GimpParamSpecChannelID GimpParamSpecChannelID;
+
+struct _GimpParamSpecChannelID
+{
+  GimpParamSpecDrawableID parent_instance;
+};
+
+GType         gimp_param_channel_id_get_type (void) G_GNUC_CONST;
+
+GParamSpec  * gimp_param_spec_channel_id     (const gchar  *name,
+                                              const gchar  *nick,
+                                              const gchar  *blurb,
+                                              Gimp         *gimp,
+                                              gboolean      none_ok,
+                                              GParamFlags   flags);
+
+GimpChannel * gimp_value_get_channel         (const GValue *value,
+                                              Gimp         *gimp);
+void          gimp_value_set_channel         (GValue       *value,
+                                              GimpChannel  *channel);
+
+
+/*
+ * GIMP_TYPE_LAYER_MASK_ID
+ */
+
+#define GIMP_TYPE_LAYER_MASK_ID               (gimp_layer_mask_id_get_type ())
+#define GIMP_VALUE_HOLDS_LAYER_MASK_ID(value) (G_TYPE_CHECK_VALUE_TYPE ((value),\
+                                               GIMP_TYPE_LAYER_MASK_ID))
+
+GType   gimp_layer_mask_id_get_type           (void) G_GNUC_CONST;
+
+
+/*
+ * GIMP_TYPE_PARAM_LAYER_MASK_ID
+ */
+
+#define GIMP_TYPE_PARAM_LAYER_MASK_ID           (gimp_param_layer_mask_id_get_type ())
+#define GIMP_PARAM_SPEC_LAYER_MASK_ID(pspec)    (G_TYPE_CHECK_INSTANCE_CAST ((pspec), GIMP_TYPE_PARAM_LAYER_MASK_ID, GimpParamSpecLayerMaskID))
+#define GIMP_IS_PARAM_SPEC_LAYER_MASK_ID(pspec) (G_TYPE_CHECK_INSTANCE_TYPE ((pspec), GIMP_TYPE_PARAM_LAYER_MASK_ID))
+
+typedef struct _GimpParamSpecLayerMaskID GimpParamSpecLayerMaskID;
+
+struct _GimpParamSpecLayerMaskID
+{
+  GimpParamSpecChannelID parent_instance;
+};
+
+GType           gimp_param_layer_mask_id_get_type (void) G_GNUC_CONST;
+
+GParamSpec    * gimp_param_spec_layer_mask_id     (const gchar   *name,
+                                                   const gchar   *nick,
+                                                   const gchar   *blurb,
+                                                   Gimp          *gimp,
+                                                   gboolean       none_ok,
+                                                   GParamFlags    flags);
+
+GimpLayerMask * gimp_value_get_layer_mask         (const GValue  *value,
+                                                   Gimp          *gimp);
+void            gimp_value_set_layer_mask         (GValue        *value,
+                                                   GimpLayerMask *layer_mask);
+
+
+/*
+ * GIMP_TYPE_SELECTION_ID
+ */
+
+#define GIMP_TYPE_SELECTION_ID               (gimp_selection_id_get_type ())
+#define GIMP_VALUE_HOLDS_SELECTION_ID(value) (G_TYPE_CHECK_VALUE_TYPE ((value),\
+                                              GIMP_TYPE_SELECTION_ID))
+
+GType   gimp_selection_id_get_type           (void) G_GNUC_CONST;
+
+
+/*
+ * GIMP_TYPE_PARAM_SELECTION_ID
+ */
+
+#define GIMP_TYPE_PARAM_SELECTION_ID           (gimp_param_selection_id_get_type ())
+#define GIMP_PARAM_SPEC_SELECTION_ID(pspec)    (G_TYPE_CHECK_INSTANCE_CAST ((pspec), GIMP_TYPE_PARAM_SELECTION_ID, GimpParamSpecSelectionID))
+#define GIMP_IS_PARAM_SPEC_SELECTION_ID(pspec) (G_TYPE_CHECK_INSTANCE_TYPE ((pspec), GIMP_TYPE_PARAM_SELECTION_ID))
+
+typedef struct _GimpParamSpecSelectionID GimpParamSpecSelectionID;
+
+struct _GimpParamSpecSelectionID
+{
+  GimpParamSpecChannelID parent_instance;
+};
+
+GType           gimp_param_selection_id_get_type (void) G_GNUC_CONST;
+
+GParamSpec    * gimp_param_spec_selection_id     (const gchar   *name,
+                                                  const gchar   *nick,
+                                                  const gchar   *blurb,
+                                                  Gimp          *gimp,
+                                                  gboolean       none_ok,
+                                                  GParamFlags    flags);
+
+GimpSelection * gimp_value_get_selection         (const GValue  *value,
+                                                  Gimp          *gimp);
+void            gimp_value_set_selection         (GValue        *value,
+                                                  GimpSelection *selection);
+
+
+/*
+ * GIMP_TYPE_VECTORS_ID
+ */
+
+#define GIMP_TYPE_VECTORS_ID               (gimp_vectors_id_get_type ())
+#define GIMP_VALUE_HOLDS_VECTORS_ID(value) (G_TYPE_CHECK_VALUE_TYPE ((value),\
+                                            GIMP_TYPE_VECTORS_ID))
+
+GType   gimp_vectors_id_get_type           (void) G_GNUC_CONST;
+
+
+/*
+ * GIMP_TYPE_PARAM_VECTORS_ID
+ */
+
+#define GIMP_TYPE_PARAM_VECTORS_ID           (gimp_param_vectors_id_get_type ())
+#define GIMP_PARAM_SPEC_VECTORS_ID(pspec)    (G_TYPE_CHECK_INSTANCE_CAST ((pspec), GIMP_TYPE_PARAM_VECTORS_ID, GimpParamSpecVectorsID))
+#define GIMP_IS_PARAM_SPEC_VECTORS_ID(pspec) (G_TYPE_CHECK_INSTANCE_TYPE ((pspec), GIMP_TYPE_PARAM_VECTORS_ID))
+
+typedef struct _GimpParamSpecVectorsID GimpParamSpecVectorsID;
+
+struct _GimpParamSpecVectorsID
+{
+  GimpParamSpecItemID parent_instance;
+};
+
+GType         gimp_param_vectors_id_get_type (void) G_GNUC_CONST;
+
+GParamSpec  * gimp_param_spec_vectors_id     (const gchar  *name,
+                                              const gchar  *nick,
+                                              const gchar  *blurb,
+                                              Gimp         *gimp,
+                                              gboolean      none_ok,
+                                              GParamFlags   flags);
+
+GimpVectors * gimp_value_get_vectors         (const GValue *value,
+                                              Gimp         *gimp);
+void          gimp_value_set_vectors         (GValue       *value,
+                                              GimpVectors  *vectors);
+
+
+/*
+ * GIMP_TYPE_DISPLAY_ID
+ */
+
+#define GIMP_TYPE_DISPLAY_ID               (gimp_display_id_get_type ())
+#define GIMP_VALUE_HOLDS_DISPLAY_ID(value) (G_TYPE_CHECK_VALUE_TYPE ((value),\
+                                            GIMP_TYPE_DISPLAY_ID))
+
+GType   gimp_display_id_get_type           (void) G_GNUC_CONST;
+
+
+/*
+ * GIMP_TYPE_PARAM_DISPLAY_ID
+ */
+
+#define GIMP_TYPE_PARAM_DISPLAY_ID           (gimp_param_display_id_get_type ())
+#define GIMP_PARAM_SPEC_DISPLAY_ID(pspec)    (G_TYPE_CHECK_INSTANCE_CAST ((pspec), GIMP_TYPE_PARAM_DISPLAY_ID, GimpParamSpecDisplayID))
+#define GIMP_IS_PARAM_SPEC_DISPLAY_ID(pspec) (G_TYPE_CHECK_INSTANCE_TYPE ((pspec), GIMP_TYPE_PARAM_DISPLAY_ID))
+
+typedef struct _GimpParamSpecDisplayID GimpParamSpecDisplayID;
+
+struct _GimpParamSpecDisplayID
+{
+  GParamSpecInt  parent_instance;
+
+  Gimp          *gimp;
+  gboolean       none_ok;
+};
+
+GType        gimp_param_display_id_get_type (void) G_GNUC_CONST;
+
+GParamSpec * gimp_param_spec_display_id     (const gchar  *name,
+                                             const gchar  *nick,
+                                             const gchar  *blurb,
+                                             Gimp         *gimp,
+                                             gboolean      none_ok,
+                                             GParamFlags   flags);
+
+GimpObject * gimp_value_get_display         (const GValue *value,
+                                             Gimp         *gimp);
+void         gimp_value_set_display         (GValue       *value,
+                                             GimpObject   *display);
+
+
+/*
+ * GIMP_TYPE_ARRAY
+ */
+
+typedef struct _GimpArray GimpArray;
+
+struct _GimpArray
+{
+  guint8   *data;
+  gsize     length;
+  gboolean  static_data;
+};
+
+GimpArray * gimp_array_new  (const guint8    *data,
+                             gsize            length,
+                             gboolean         static_data);
+GimpArray * gimp_array_copy (const GimpArray *array);
+void        gimp_array_free (GimpArray       *array);
+
+#define GIMP_TYPE_ARRAY               (gimp_array_get_type ())
+#define GIMP_VALUE_HOLDS_ARRAY(value) (G_TYPE_CHECK_VALUE_TYPE ((value), GIMP_TYPE_ARRAY))
+
+GType   gimp_array_get_type           (void) G_GNUC_CONST;
+
+
+/*
+ * GIMP_TYPE_PARAM_ARRAY
+ */
+
+#define GIMP_TYPE_PARAM_ARRAY           (gimp_param_array_get_type ())
+#define GIMP_PARAM_SPEC_ARRAY(pspec)    (G_TYPE_CHECK_INSTANCE_CAST ((pspec), GIMP_TYPE_PARAM_ARRAY, GimpParamSpecArray))
+#define GIMP_IS_PARAM_SPEC_ARRAY(pspec) (G_TYPE_CHECK_INSTANCE_TYPE ((pspec), GIMP_TYPE_PARAM_ARRAY))
+
+typedef struct _GimpParamSpecArray GimpParamSpecArray;
+
+struct _GimpParamSpecArray
+{
+  GParamSpecBoxed parent_instance;
+};
+
+GType        gimp_param_array_get_type (void) G_GNUC_CONST;
+
+GParamSpec * gimp_param_spec_array     (const gchar  *name,
+                                        const gchar  *nick,
+                                        const gchar  *blurb,
+                                        GParamFlags   flags);
+
+
+/*
+ * GIMP_TYPE_INT8_ARRAY
+ */
+
+#define GIMP_TYPE_INT8_ARRAY               (gimp_int8_array_get_type ())
+#define GIMP_VALUE_HOLDS_INT8_ARRAY(value) (G_TYPE_CHECK_VALUE_TYPE ((value), GIMP_TYPE_INT8_ARRAY))
+
+GType   gimp_int8_array_get_type           (void) G_GNUC_CONST;
+
+
+/*
+ * GIMP_TYPE_PARAM_INT8_ARRAY
+ */
+
+#define GIMP_TYPE_PARAM_INT8_ARRAY           (gimp_param_int8_array_get_type ())
+#define GIMP_PARAM_SPEC_INT8_ARRAY(pspec)    (G_TYPE_CHECK_INSTANCE_CAST ((pspec), GIMP_TYPE_PARAM_INT8_ARRAY, GimpParamSpecInt8Array))
+#define GIMP_IS_PARAM_SPEC_INT8_ARRAY(pspec) (G_TYPE_CHECK_INSTANCE_TYPE ((pspec), GIMP_TYPE_PARAM_INT8_ARRAY))
+
+typedef struct _GimpParamSpecInt8Array GimpParamSpecInt8Array;
+
+struct _GimpParamSpecInt8Array
+{
+  GimpParamSpecArray parent_instance;
+};
+
+GType          gimp_param_int8_array_get_type  (void) G_GNUC_CONST;
+
+GParamSpec   * gimp_param_spec_int8_array      (const gchar  *name,
+                                                const gchar  *nick,
+                                                const gchar  *blurb,
+                                                GParamFlags   flags);
+
+const guint8 * gimp_value_get_int8array        (const GValue *value);
+guint8       * gimp_value_dup_int8array        (const GValue *value);
+void           gimp_value_set_int8array        (GValue       *value,
+                                                const guint8 *array,
+                                                gsize         length);
+void           gimp_value_set_static_int8array (GValue       *value,
+                                                const guint8 *array,
+                                                gsize         length);
+void           gimp_value_take_int8array       (GValue       *value,
+                                                guint8       *array,
+                                                gsize         length);
+
+
+/*
+ * GIMP_TYPE_INT16_ARRAY
+ */
+
+#define GIMP_TYPE_INT16_ARRAY               (gimp_int16_array_get_type ())
+#define GIMP_VALUE_HOLDS_INT16_ARRAY(value) (G_TYPE_CHECK_VALUE_TYPE ((value), GIMP_TYPE_INT16_ARRAY))
+
+GType   gimp_int16_array_get_type           (void) G_GNUC_CONST;
+
+
+/*
+ * GIMP_TYPE_PARAM_INT16_ARRAY
+ */
+
+#define GIMP_TYPE_PARAM_INT16_ARRAY           (gimp_param_int16_array_get_type ())
+#define GIMP_PARAM_SPEC_INT16_ARRAY(pspec)    (G_TYPE_CHECK_INSTANCE_CAST ((pspec), GIMP_TYPE_PARAM_INT16_ARRAY, GimpParamSpecInt16Array))
+#define GIMP_IS_PARAM_SPEC_INT16_ARRAY(pspec) (G_TYPE_CHECK_INSTANCE_TYPE ((pspec), GIMP_TYPE_PARAM_INT16_ARRAY))
+
+typedef struct _GimpParamSpecInt16Array GimpParamSpecInt16Array;
+
+struct _GimpParamSpecInt16Array
+{
+  GimpParamSpecArray parent_instance;
+};
+
+GType          gimp_param_int16_array_get_type  (void) G_GNUC_CONST;
+
+GParamSpec   * gimp_param_spec_int16_array      (const gchar  *name,
+                                                 const gchar  *nick,
+                                                 const gchar  *blurb,
+                                                 GParamFlags   flags);
+
+const gint16 * gimp_value_get_int16array        (const GValue *value);
+gint16       * gimp_value_dup_int16array        (const GValue *value);
+void           gimp_value_set_int16array        (GValue       *value,
+                                                 const gint16 *array,
+                                                 gsize         length);
+void           gimp_value_set_static_int16array (GValue       *value,
+                                                 const gint16 *array,
+                                                 gsize         length);
+void           gimp_value_take_int16array       (GValue       *value,
+                                                 gint16       *array,
+                                                 gsize         length);
+
+
+/*
+ * GIMP_TYPE_INT32_ARRAY
+ */
+
+#define GIMP_TYPE_INT32_ARRAY               (gimp_int32_array_get_type ())
+#define GIMP_VALUE_HOLDS_INT32_ARRAY(value) (G_TYPE_CHECK_VALUE_TYPE ((value), GIMP_TYPE_INT32_ARRAY))
+
+GType   gimp_int32_array_get_type           (void) G_GNUC_CONST;
+
+
+/*
+ * GIMP_TYPE_PARAM_INT32_ARRAY
+ */
+
+#define GIMP_TYPE_PARAM_INT32_ARRAY           (gimp_param_int32_array_get_type ())
+#define GIMP_PARAM_SPEC_INT32_ARRAY(pspec)    (G_TYPE_CHECK_INSTANCE_CAST ((pspec), GIMP_TYPE_PARAM_INT32_ARRAY, GimpParamSpecInt32Array))
+#define GIMP_IS_PARAM_SPEC_INT32_ARRAY(pspec) (G_TYPE_CHECK_INSTANCE_TYPE ((pspec), GIMP_TYPE_PARAM_INT32_ARRAY))
+
+typedef struct _GimpParamSpecInt32Array GimpParamSpecInt32Array;
+
+struct _GimpParamSpecInt32Array
+{
+  GimpParamSpecArray parent_instance;
+};
+
+GType          gimp_param_int32_array_get_type  (void) G_GNUC_CONST;
+
+GParamSpec   * gimp_param_spec_int32_array      (const gchar  *name,
+                                                 const gchar  *nick,
+                                                 const gchar  *blurb,
+                                                 GParamFlags   flags);
+
+const gint32 * gimp_value_get_int32array        (const GValue *value);
+gint32       * gimp_value_dup_int32array        (const GValue *value);
+void           gimp_value_set_int32array        (GValue       *value,
+                                                 const gint32 *array,
+                                                 gsize         length);
+void           gimp_value_set_static_int32array (GValue       *value,
+                                                 const gint32 *array,
+                                                 gsize         length);
+void           gimp_value_take_int32array       (GValue       *value,
+                                                 gint32       *array,
+                                                 gsize         length);
+
+
+/*
+ * GIMP_TYPE_FLOAT_ARRAY
+ */
+
+#define GIMP_TYPE_FLOAT_ARRAY               (gimp_float_array_get_type ())
+#define GIMP_VALUE_HOLDS_FLOAT_ARRAY(value) (G_TYPE_CHECK_VALUE_TYPE ((value), GIMP_TYPE_FLOAT_ARRAY))
+
+GType   gimp_float_array_get_type           (void) G_GNUC_CONST;
+
+
+/*
+ * GIMP_TYPE_PARAM_FLOAT_ARRAY
+ */
+
+#define GIMP_TYPE_PARAM_FLOAT_ARRAY           (gimp_param_float_array_get_type ())
+#define GIMP_PARAM_SPEC_FLOAT_ARRAY(pspec)    (G_TYPE_CHECK_INSTANCE_CAST ((pspec), GIMP_TYPE_PARAM_FLOAT_ARRAY, GimpParamSpecFloatArray))
+#define GIMP_IS_PARAM_SPEC_FLOAT_ARRAY(pspec) (G_TYPE_CHECK_INSTANCE_TYPE ((pspec), GIMP_TYPE_PARAM_FLOAT_ARRAY))
+
+typedef struct _GimpParamSpecFloatArray GimpParamSpecFloatArray;
+
+struct _GimpParamSpecFloatArray
+{
+  GimpParamSpecArray parent_instance;
+};
+
+GType           gimp_param_float_array_get_type  (void) G_GNUC_CONST;
+
+GParamSpec    * gimp_param_spec_float_array      (const gchar  *name,
+                                                  const gchar  *nick,
+                                                  const gchar  *blurb,
+                                                  GParamFlags   flags);
+
+const gdouble * gimp_value_get_floatarray        (const GValue  *value);
+gdouble       * gimp_value_dup_floatarray        (const GValue  *value);
+void            gimp_value_set_floatarray        (GValue        *value,
+                                                  const gdouble *array,
+                                                  gsize         length);
+void            gimp_value_set_static_floatarray (GValue        *value,
+                                                  const gdouble *array,
+                                                  gsize         length);
+void            gimp_value_take_floatarray       (GValue        *value,
+                                                  gdouble       *array,
+                                                  gsize         length);
+
+
+/*
+ * GIMP_TYPE_STRING_ARRAY
+ */
+
+GimpArray * gimp_string_array_new  (const gchar     **data,
+                                    gsize             length,
+                                    gboolean          static_data);
+GimpArray * gimp_string_array_copy (const GimpArray  *array);
+void        gimp_string_array_free (GimpArray        *array);
+
+#define GIMP_TYPE_STRING_ARRAY               (gimp_string_array_get_type ())
+#define GIMP_VALUE_HOLDS_STRING_ARRAY(value) (G_TYPE_CHECK_VALUE_TYPE ((value), GIMP_TYPE_STRING_ARRAY))
+
+GType   gimp_string_array_get_type           (void) G_GNUC_CONST;
+
+
+/*
+ * GIMP_TYPE_PARAM_STRING_ARRAY
+ */
+
+#define GIMP_TYPE_PARAM_STRING_ARRAY           (gimp_param_string_array_get_type ())
+#define GIMP_PARAM_SPEC_STRING_ARRAY(pspec)    (G_TYPE_CHECK_INSTANCE_CAST ((pspec), GIMP_TYPE_PARAM_STRING_ARRAY, GimpParamSpecStringArray))
+#define GIMP_IS_PARAM_SPEC_STRING_ARRAY(pspec) (G_TYPE_CHECK_INSTANCE_TYPE ((pspec), GIMP_TYPE_PARAM_STRING_ARRAY))
+
+typedef struct _GimpParamSpecStringArray GimpParamSpecStringArray;
+
+struct _GimpParamSpecStringArray
+{
+  GParamSpecBoxed parent_instance;
+};
+
+GType          gimp_param_string_array_get_type  (void) G_GNUC_CONST;
+
+GParamSpec   * gimp_param_spec_string_array      (const gchar  *name,
+                                                  const gchar  *nick,
+                                                  const gchar  *blurb,
+                                                  GParamFlags   flags);
+
+const gchar ** gimp_value_get_stringarray        (const GValue *value);
+gchar       ** gimp_value_dup_stringarray        (const GValue *value);
+void           gimp_value_set_stringarray        (GValue       *value,
+                                                  const gchar **array,
+                                                  gsize         length);
+void           gimp_value_set_static_stringarray (GValue       *value,
+                                                  const gchar **array,
+                                                  gsize         length);
+void           gimp_value_take_stringarray       (GValue       *value,
+                                                  gchar       **array,
+                                                  gsize         length);
+
+
+/*
+ * GIMP_TYPE_COLOR_ARRAY
+ */
+
+#define GIMP_TYPE_COLOR_ARRAY               (gimp_color_array_get_type ())
+#define GIMP_VALUE_HOLDS_COLOR_ARRAY(value) (G_TYPE_CHECK_VALUE_TYPE ((value), GIMP_TYPE_COLOR_ARRAY))
+
+GType   gimp_color_array_get_type           (void) G_GNUC_CONST;
+
+
+/*
+ * GIMP_TYPE_PARAM_COLOR_ARRAY
+ */
+
+#define GIMP_TYPE_PARAM_COLOR_ARRAY           (gimp_param_color_array_get_type ())
+#define GIMP_PARAM_SPEC_COLOR_ARRAY(pspec)    (G_TYPE_CHECK_INSTANCE_CAST ((pspec), GIMP_TYPE_PARAM_COLOR_ARRAY, GimpParamSpecColorArray))
+#define GIMP_IS_PARAM_SPEC_COLOR_ARRAY(pspec) (G_TYPE_CHECK_INSTANCE_TYPE ((pspec), GIMP_TYPE_PARAM_COLOR_ARRAY))
+
+typedef struct _GimpParamSpecColorArray GimpParamSpecColorArray;
+
+struct _GimpParamSpecColorArray
+{
+  GParamSpecBoxed parent_instance;
+};
+
+GType           gimp_param_color_array_get_type  (void) G_GNUC_CONST;
+
+GParamSpec    * gimp_param_spec_color_array      (const gchar   *name,
+                                                  const gchar   *nick,
+                                                  const gchar   *blurb,
+                                                  GParamFlags    flags);
+
+const GimpRGB * gimp_value_get_colorarray        (const GValue  *value);
+GimpRGB       * gimp_value_dup_colorarray        (const GValue  *value);
+void            gimp_value_set_colorarray        (GValue        *value,
+                                                  const GimpRGB *array,
+                                                  gsize          length);
+void            gimp_value_set_static_colorarray (GValue        *value,
+                                                  const GimpRGB *array,
+                                                  gsize          length);
+void            gimp_value_take_colorarray       (GValue        *value,
+                                                  GimpRGB       *array,
+                                                  gsize          length);
+
+
+#endif  /*  __GIMP_PARAM_SPECS_H__  */
diff --git a/app/core/gimpparasitelist.c b/app/core/gimpparasitelist.c
new file mode 100644
index 0000000..70a81fa
--- /dev/null
+++ b/app/core/gimpparasitelist.c
@@ -0,0 +1,453 @@
+/* parasitelist.c: Copyright 1998 Jay Cox <jaycox@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <gio/gio.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpconfig/gimpconfig.h"
+
+#include "core-types.h"
+
+#include "gimp-memsize.h"
+#include "gimpmarshal.h"
+#include "gimpparasitelist.h"
+
+
+enum
+{
+  ADD,
+  REMOVE,
+  LAST_SIGNAL
+};
+
+
+static void     gimp_parasite_list_finalize          (GObject     *object);
+static gint64   gimp_parasite_list_get_memsize       (GimpObject  *object,
+                                                      gint64      *gui_size);
+
+static void     gimp_parasite_list_config_iface_init (gpointer     iface,
+                                                      gpointer     iface_data);
+static gboolean gimp_parasite_list_serialize    (GimpConfig       *list,
+                                                 GimpConfigWriter *writer,
+                                                 gpointer          data);
+static gboolean gimp_parasite_list_deserialize  (GimpConfig       *list,
+                                                 GScanner         *scanner,
+                                                 gint              nest_level,
+                                                 gpointer          data);
+
+static void     parasite_serialize           (const gchar      *key,
+                                              GimpParasite     *parasite,
+                                              GimpConfigWriter *writer);
+static void     parasite_copy                (const gchar      *key,
+                                              GimpParasite     *parasite,
+                                              GimpParasiteList *list);
+static gboolean parasite_free                (const gchar      *key,
+                                              GimpParasite     *parasite,
+                                              gpointer          unused);
+static void     parasite_count_if_persistent (const gchar      *key,
+                                              GimpParasite     *parasite,
+                                              gint             *count);
+
+
+G_DEFINE_TYPE_WITH_CODE (GimpParasiteList, gimp_parasite_list, GIMP_TYPE_OBJECT,
+                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_CONFIG,
+                                                gimp_parasite_list_config_iface_init))
+
+#define parent_class gimp_parasite_list_parent_class
+
+static guint        parasite_list_signals[LAST_SIGNAL] = { 0 };
+static const gchar  parasite_symbol[]                  = "parasite";
+
+
+static void
+gimp_parasite_list_class_init (GimpParasiteListClass *klass)
+{
+  GObjectClass    *object_class      = G_OBJECT_CLASS (klass);
+  GimpObjectClass *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+
+  parasite_list_signals[ADD] =
+    g_signal_new ("add",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpParasiteListClass, add),
+                  NULL, NULL,
+                  gimp_marshal_VOID__POINTER,
+                  G_TYPE_NONE, 1,
+                  G_TYPE_POINTER);
+
+  parasite_list_signals[REMOVE] =
+    g_signal_new ("remove",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpParasiteListClass, remove),
+                  NULL, NULL,
+                  gimp_marshal_VOID__POINTER,
+                  G_TYPE_NONE, 1,
+                  G_TYPE_POINTER);
+
+  object_class->finalize         = gimp_parasite_list_finalize;
+
+  gimp_object_class->get_memsize = gimp_parasite_list_get_memsize;
+
+  klass->add                     = NULL;
+  klass->remove                  = NULL;
+}
+
+static void
+gimp_parasite_list_config_iface_init (gpointer  iface,
+                                      gpointer  iface_data)
+{
+  GimpConfigInterface *config_iface = (GimpConfigInterface *) iface;
+
+  config_iface->serialize   = gimp_parasite_list_serialize;
+  config_iface->deserialize = gimp_parasite_list_deserialize;
+}
+
+static void
+gimp_parasite_list_init (GimpParasiteList *list)
+{
+  list->table = NULL;
+}
+
+static void
+gimp_parasite_list_finalize (GObject *object)
+{
+  GimpParasiteList *list = GIMP_PARASITE_LIST (object);
+
+  if (list->table)
+    {
+      g_hash_table_foreach_remove (list->table, (GHRFunc) parasite_free, NULL);
+      g_hash_table_destroy (list->table);
+      list->table = NULL;
+    }
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static gint64
+gimp_parasite_list_get_memsize (GimpObject *object,
+                                gint64     *gui_size)
+{
+  GimpParasiteList *list    = GIMP_PARASITE_LIST (object);
+  gint64            memsize = 0;
+
+  memsize += gimp_g_hash_table_get_memsize_foreach (list->table,
+                                                    (GimpMemsizeFunc)
+                                                    gimp_parasite_get_memsize,
+                                                    gui_size);
+
+  return memsize + GIMP_OBJECT_CLASS (parent_class)->get_memsize (object,
+                                                                  gui_size);
+}
+
+static gboolean
+gimp_parasite_list_serialize (GimpConfig       *list,
+                              GimpConfigWriter *writer,
+                              gpointer          data)
+{
+  if (GIMP_PARASITE_LIST (list)->table)
+    g_hash_table_foreach (GIMP_PARASITE_LIST (list)->table,
+                          (GHFunc) parasite_serialize,
+                          writer);
+
+  return TRUE;
+}
+
+static gboolean
+gimp_parasite_list_deserialize (GimpConfig *list,
+                                GScanner   *scanner,
+                                gint        nest_level,
+                                gpointer    data)
+{
+  GTokenType token;
+
+  g_scanner_scope_add_symbol (scanner, 0,
+                              parasite_symbol, (gpointer) parasite_symbol);
+
+  token = G_TOKEN_LEFT_PAREN;
+
+  while (g_scanner_peek_next_token (scanner) == token)
+    {
+      token = g_scanner_get_next_token (scanner);
+
+      switch (token)
+        {
+        case G_TOKEN_LEFT_PAREN:
+          token = G_TOKEN_SYMBOL;
+          break;
+
+        case G_TOKEN_SYMBOL:
+          if (scanner->value.v_symbol == parasite_symbol)
+            {
+              gchar        *parasite_name      = NULL;
+              gint          parasite_flags     = 0;
+              guint8       *parasite_data      = NULL;
+              gint          parasite_data_size = 0;
+              GimpParasite *parasite;
+
+              token = G_TOKEN_STRING;
+
+              if (g_scanner_peek_next_token (scanner) != token)
+                break;
+
+              if (! gimp_scanner_parse_string (scanner, &parasite_name))
+                break;
+
+              token = G_TOKEN_INT;
+
+              if (g_scanner_peek_next_token (scanner) != token)
+                goto cleanup;
+
+              if (! gimp_scanner_parse_int (scanner, &parasite_flags))
+                goto cleanup;
+
+              token = G_TOKEN_INT;
+
+              if (g_scanner_peek_next_token (scanner) != token)
+                {
+                  /*  old format -- plain string  */
+
+                  gchar *str;
+
+                  if (g_scanner_peek_next_token (scanner) != G_TOKEN_STRING)
+                    goto cleanup;
+
+                  if (! gimp_scanner_parse_string (scanner, &str))
+                    goto cleanup;
+
+                  parasite_data_size = strlen (str);
+                  parasite_data      = (guint8 *) str;
+                }
+              else
+                {
+                  /*  new format -- properly encoded binary data  */
+
+                  if (! gimp_scanner_parse_int (scanner, &parasite_data_size))
+                    goto cleanup;
+
+                  token = G_TOKEN_STRING;
+
+                  if (g_scanner_peek_next_token (scanner) != token)
+                    goto cleanup;
+
+                  if (! gimp_scanner_parse_data (scanner, parasite_data_size,
+                                                 &parasite_data))
+                    goto cleanup;
+                }
+
+              parasite = gimp_parasite_new (parasite_name,
+                                            parasite_flags,
+                                            parasite_data_size,
+                                            parasite_data);
+              gimp_parasite_list_add (GIMP_PARASITE_LIST (list),
+                                      parasite);  /* adds a copy */
+              gimp_parasite_free (parasite);
+
+              token = G_TOKEN_RIGHT_PAREN;
+
+              g_free (parasite_data);
+            cleanup:
+              g_free (parasite_name);
+            }
+          break;
+
+        case G_TOKEN_RIGHT_PAREN:
+          token = G_TOKEN_LEFT_PAREN;
+          break;
+
+        default: /* do nothing */
+          break;
+        }
+    }
+
+  return gimp_config_deserialize_return (scanner, token, nest_level);
+}
+
+GimpParasiteList *
+gimp_parasite_list_new (void)
+{
+  GimpParasiteList *list;
+
+  list = g_object_new (GIMP_TYPE_PARASITE_LIST, NULL);
+
+  return list;
+}
+
+GimpParasiteList *
+gimp_parasite_list_copy (GimpParasiteList *list)
+{
+  GimpParasiteList *newlist;
+
+  g_return_val_if_fail (GIMP_IS_PARASITE_LIST (list), NULL);
+
+  newlist = gimp_parasite_list_new ();
+
+  if (list->table)
+    g_hash_table_foreach (list->table, (GHFunc) parasite_copy, newlist);
+
+  return newlist;
+}
+
+void
+gimp_parasite_list_add (GimpParasiteList   *list,
+                        const GimpParasite *parasite)
+{
+  GimpParasite *copy;
+
+  g_return_if_fail (GIMP_IS_PARASITE_LIST (list));
+  g_return_if_fail (parasite != NULL);
+  g_return_if_fail (parasite->name != NULL);
+
+  if (list->table == NULL)
+    list->table = g_hash_table_new (g_str_hash, g_str_equal);
+
+  gimp_parasite_list_remove (list, parasite->name);
+  copy = gimp_parasite_copy (parasite);
+  g_hash_table_insert (list->table, copy->name, copy);
+
+  g_signal_emit (list, parasite_list_signals[ADD], 0, copy);
+}
+
+void
+gimp_parasite_list_remove (GimpParasiteList *list,
+                           const gchar      *name)
+{
+  g_return_if_fail (GIMP_IS_PARASITE_LIST (list));
+
+  if (list->table)
+    {
+      GimpParasite *parasite;
+
+      parasite = (GimpParasite *) gimp_parasite_list_find (list, name);
+
+      if (parasite)
+        {
+          g_hash_table_remove (list->table, name);
+
+          g_signal_emit (list, parasite_list_signals[REMOVE], 0, parasite);
+
+          gimp_parasite_free (parasite);
+        }
+    }
+}
+
+gint
+gimp_parasite_list_length (GimpParasiteList *list)
+{
+  g_return_val_if_fail (GIMP_IS_PARASITE_LIST (list), 0);
+
+  if (! list->table)
+    return 0;
+
+  return g_hash_table_size (list->table);
+}
+
+gint
+gimp_parasite_list_persistent_length (GimpParasiteList *list)
+{
+  gint len = 0;
+
+  g_return_val_if_fail (GIMP_IS_PARASITE_LIST (list), 0);
+
+  if (! list->table)
+    return 0;
+
+  gimp_parasite_list_foreach (list,
+                              (GHFunc) parasite_count_if_persistent, &len);
+
+  return len;
+}
+
+void
+gimp_parasite_list_foreach (GimpParasiteList *list,
+                            GHFunc            function,
+                            gpointer          user_data)
+{
+  g_return_if_fail (GIMP_IS_PARASITE_LIST (list));
+
+  if (! list->table)
+    return;
+
+  g_hash_table_foreach (list->table, function, user_data);
+}
+
+const GimpParasite *
+gimp_parasite_list_find (GimpParasiteList *list,
+                         const gchar      *name)
+{
+  g_return_val_if_fail (GIMP_IS_PARASITE_LIST (list), NULL);
+
+  if (list->table)
+    return (GimpParasite *) g_hash_table_lookup (list->table, name);
+
+  return NULL;
+}
+
+
+static void
+parasite_serialize (const gchar      *key,
+                    GimpParasite     *parasite,
+                    GimpConfigWriter *writer)
+{
+  if (! gimp_parasite_is_persistent (parasite))
+    return;
+
+  gimp_config_writer_open (writer, parasite_symbol);
+
+  gimp_config_writer_printf (writer, "\"%s\" %lu %lu",
+                             gimp_parasite_name (parasite),
+                             gimp_parasite_flags (parasite),
+                             gimp_parasite_data_size (parasite));
+
+  gimp_config_writer_data (writer,
+                           gimp_parasite_data_size (parasite),
+                           gimp_parasite_data (parasite));
+
+  gimp_config_writer_close (writer);
+  gimp_config_writer_linefeed (writer);
+}
+
+static void
+parasite_copy (const gchar      *key,
+               GimpParasite     *parasite,
+               GimpParasiteList *list)
+{
+  gimp_parasite_list_add (list, parasite);
+}
+
+static gboolean
+parasite_free (const gchar  *key,
+               GimpParasite *parasite,
+               gpointer     unused)
+{
+  gimp_parasite_free (parasite);
+
+  return TRUE;
+}
+
+static void
+parasite_count_if_persistent (const gchar  *key,
+                              GimpParasite *parasite,
+                              gint         *count)
+{
+  if (gimp_parasite_is_persistent (parasite))
+    *count = *count + 1;
+}
diff --git a/app/core/gimpparasitelist.h b/app/core/gimpparasitelist.h
new file mode 100644
index 0000000..1762753
--- /dev/null
+++ b/app/core/gimpparasitelist.h
@@ -0,0 +1,69 @@
+/* parasitelist.h: Copyright 1998 Jay Cox <jaycox@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_PARASITE_LIST_H__
+#define __GIMP_PARASITE_LIST_H__
+
+
+#include "gimpobject.h"
+
+
+#define GIMP_TYPE_PARASITE_LIST            (gimp_parasite_list_get_type ())
+#define GIMP_PARASITE_LIST(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_PARASITE_LIST, GimpParasiteList))
+#define GIMP_PARASITE_LIST_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_PARASITE_LIST, GimpParasiteListClass))
+#define GIMP_IS_PARASITE_LIST(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_PARASITE_LIST))
+#define GIMP_IS_PARASITE_LIST_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_PARASITE_LIST))
+#define GIMP_PARASITE_LIST_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_PARASITE_LIST, GimpParasiteListClass))
+
+
+typedef struct _GimpParasiteListClass GimpParasiteListClass;
+
+struct _GimpParasiteList
+{
+  GimpObject  object;
+
+  GHashTable *table;
+};
+
+struct _GimpParasiteListClass
+{
+  GimpObjectClass parent_class;
+
+  void (* add)    (GimpParasiteList *list,
+                   GimpParasite     *parasite);
+  void (* remove) (GimpParasiteList *list,
+                   GimpParasite     *parasite);
+};
+
+
+GType                gimp_parasite_list_get_type (void) G_GNUC_CONST;
+
+GimpParasiteList   * gimp_parasite_list_new      (void);
+GimpParasiteList   * gimp_parasite_list_copy     (GimpParasiteList       *list);
+void                 gimp_parasite_list_add      (GimpParasiteList       *list,
+                                                  const GimpParasite     *parasite);
+void                 gimp_parasite_list_remove   (GimpParasiteList       *list,
+                                                  const gchar            *name);
+gint                 gimp_parasite_list_length   (GimpParasiteList       *list);
+gint                 gimp_parasite_list_persistent_length (GimpParasiteList *list);
+void                 gimp_parasite_list_foreach  (GimpParasiteList       *list,
+                                                  GHFunc                  function,
+                                                  gpointer                user_data);
+const GimpParasite * gimp_parasite_list_find     (GimpParasiteList       *list,
+                                                  const gchar            *name);
+
+
+#endif  /*  __GIMP_PARASITE_LIST_H__  */
diff --git a/app/core/gimppattern-header.h b/app/core/gimppattern-header.h
new file mode 100644
index 0000000..e11b3c9
--- /dev/null
+++ b/app/core/gimppattern-header.h
@@ -0,0 +1,48 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_PATTERN_HEADER_H__
+#define __GIMP_PATTERN_HEADER_H__
+
+
+#define GIMP_PATTERN_MAGIC    (('G' << 24) + ('P' << 16) + \
+                               ('A' << 8)  + ('T' << 0))
+#define GIMP_PATTERN_MAX_SIZE 10000 /* Max size in either dimension in px */
+#define GIMP_PATTERN_MAX_NAME 256   /* Max length of the pattern's name   */
+
+
+/*  All field entries are MSB  */
+
+typedef struct _GimpPatternHeader GimpPatternHeader;
+
+struct _GimpPatternHeader
+{
+  guint32   header_size;  /*  = sizeof (GimpPatternHeader) + pattern name  */
+  guint32   version;      /*  pattern file version #  */
+  guint32   width;        /*  width of pattern  */
+  guint32   height;       /*  height of pattern  */
+  guint32   bytes;        /*  depth of pattern in bytes  */
+  guint32   magic_number; /*  GIMP pattern magic number  */
+};
+
+/*  In a pattern file, next comes the pattern name, null-terminated.
+ *  After that comes the pattern data -- width * height * bytes bytes
+ *  of it...
+ */
+
+
+#endif  /* __GIMP_PATTERN_HEADER_H__ */
diff --git a/app/core/gimppattern-load.c b/app/core/gimppattern-load.c
new file mode 100644
index 0000000..27f057f
--- /dev/null
+++ b/app/core/gimppattern-load.c
@@ -0,0 +1,220 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <cairo.h>
+#include <gegl.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpcolor/gimpcolor.h"
+
+#include "core-types.h"
+
+#include "gimppattern.h"
+#include "gimppattern-header.h"
+#include "gimppattern-load.h"
+#include "gimptempbuf.h"
+
+#include "gimp-intl.h"
+
+
+GList *
+gimp_pattern_load (GimpContext   *context,
+                   GFile         *file,
+                   GInputStream  *input,
+                   GError       **error)
+{
+  GimpPattern       *pattern = NULL;
+  const Babl        *format  = NULL;
+  GimpPatternHeader  header;
+  gsize              size;
+  gsize              bytes_read;
+  gsize              bn_size;
+  gchar             *name = NULL;
+
+  g_return_val_if_fail (G_IS_FILE (file), NULL);
+  g_return_val_if_fail (G_IS_INPUT_STREAM (input), NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, NULL);
+
+  /*  read the size  */
+  if (! g_input_stream_read_all (input, &header, sizeof (header),
+                                 &bytes_read, NULL, error) ||
+      bytes_read != sizeof (header))
+    {
+      g_prefix_error (error, _("File appears truncated: "));
+      goto error;
+    }
+
+  /*  rearrange the bytes in each unsigned int  */
+  header.header_size  = g_ntohl (header.header_size);
+  header.version      = g_ntohl (header.version);
+  header.width        = g_ntohl (header.width);
+  header.height       = g_ntohl (header.height);
+  header.bytes        = g_ntohl (header.bytes);
+  header.magic_number = g_ntohl (header.magic_number);
+
+  /*  Check for correct file format */
+  if (header.magic_number != GIMP_PATTERN_MAGIC ||
+      header.version      != 1                  ||
+      header.header_size  <= sizeof (header))
+    {
+      g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                   _("Unknown pattern format version %d."),
+                   header.version);
+      goto error;
+    }
+
+  /*  Check for supported bit depths  */
+  if (header.bytes < 1 || header.bytes > 4)
+    {
+      g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                   _("Unsupported pattern depth %d.\n"
+                     "GIMP Patterns must be GRAY or RGB."),
+                   header.bytes);
+      goto error;
+    }
+
+  /*  Validate dimensions  */
+  if ((header.width  == 0) || (header.width  > GIMP_PATTERN_MAX_SIZE) ||
+      (header.height == 0) || (header.height > GIMP_PATTERN_MAX_SIZE) ||
+      (G_MAXSIZE / header.width / header.height / header.bytes < 1))
+    {
+      g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                   _("Invalid header data in '%s': width=%lu (maximum %lu), "
+                     "height=%lu (maximum %lu), bytes=%lu"),
+                   gimp_file_get_utf8_name (file),
+                   (gulong) header.width,  (gulong) GIMP_PATTERN_MAX_SIZE,
+                   (gulong) header.height, (gulong) GIMP_PATTERN_MAX_SIZE,
+                   (gulong) header.bytes);
+      goto error;
+    }
+
+  /*  Read in the pattern name  */
+  if ((bn_size = (header.header_size - sizeof (header))))
+    {
+      gchar *utf8;
+
+      if (bn_size > GIMP_PATTERN_MAX_NAME)
+        {
+          g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                       _("Invalid header data in '%s': "
+                         "Pattern name is too long: %lu"),
+                       gimp_file_get_utf8_name (file),
+                       (gulong) bn_size);
+          goto error;
+        }
+
+      name = g_new0 (gchar, bn_size + 1);
+
+      if (! g_input_stream_read_all (input, name, bn_size,
+                                     &bytes_read, NULL, error) ||
+          bytes_read != bn_size)
+        {
+          g_prefix_error (error, _("File appears truncated."));
+          g_free (name);
+          goto error;
+        }
+
+      utf8 = gimp_any_to_utf8 (name, bn_size - 1,
+                               _("Invalid UTF-8 string in pattern file '%s'."),
+                               gimp_file_get_utf8_name (file));
+      g_free (name);
+      name = utf8;
+    }
+
+  if (! name)
+    name = g_strdup (_("Unnamed"));
+
+  pattern = g_object_new (GIMP_TYPE_PATTERN,
+                          "name",      name,
+                          "mime-type", "image/x-gimp-pat",
+                          NULL);
+
+  g_free (name);
+
+  switch (header.bytes)
+    {
+    case 1: format = babl_format ("Y' u8");      break;
+    case 2: format = babl_format ("Y'A u8");     break;
+    case 3: format = babl_format ("R'G'B' u8");  break;
+    case 4: format = babl_format ("R'G'B'A u8"); break;
+    }
+
+  pattern->mask = gimp_temp_buf_new (header.width, header.height, format);
+  size = (gsize) header.width * header.height * header.bytes;
+
+  if (! g_input_stream_read_all (input,
+                                 gimp_temp_buf_get_data (pattern->mask), size,
+                                 &bytes_read, NULL, error) ||
+      bytes_read != size)
+    {
+      g_prefix_error (error, _("File appears truncated."));
+      goto error;
+    }
+
+  return g_list_prepend (NULL, pattern);
+
+ error:
+
+  if (pattern)
+    g_object_unref (pattern);
+
+  g_prefix_error (error, _("Fatal parse error in pattern file: "));
+
+  return NULL;
+}
+
+GList *
+gimp_pattern_load_pixbuf (GimpContext   *context,
+                          GFile         *file,
+                          GInputStream  *input,
+                          GError       **error)
+{
+  GimpPattern *pattern;
+  GdkPixbuf   *pixbuf;
+  gchar       *name;
+
+  g_return_val_if_fail (G_IS_FILE (file), NULL);
+  g_return_val_if_fail (G_IS_INPUT_STREAM (input), NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, NULL);
+
+  pixbuf = gdk_pixbuf_new_from_stream (input, NULL, error);
+  if (! pixbuf)
+    return NULL;
+
+  name = g_strdup (gdk_pixbuf_get_option (pixbuf, "tEXt::Title"));
+
+  if (! name)
+    name = g_strdup (gdk_pixbuf_get_option (pixbuf, "tEXt::Comment"));
+
+  if (! name)
+    name = g_path_get_basename (gimp_file_get_utf8_name (file));
+
+  pattern = g_object_new (GIMP_TYPE_PATTERN,
+                          "name",      name,
+                          "mime-type", NULL, /* FIXME!! */
+                          NULL);
+  g_free (name);
+
+  pattern->mask = gimp_temp_buf_new_from_pixbuf (pixbuf, NULL);
+
+  g_object_unref (pixbuf);
+
+  return g_list_prepend (NULL, pattern);
+}
diff --git a/app/core/gimppattern-load.h b/app/core/gimppattern-load.h
new file mode 100644
index 0000000..8e7fc8a
--- /dev/null
+++ b/app/core/gimppattern-load.h
@@ -0,0 +1,35 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_PATTERN_LOAD_H__
+#define __GIMP_PATTERN_LOAD_H__
+
+
+#define GIMP_PATTERN_FILE_EXTENSION ".pat"
+
+
+GList * gimp_pattern_load        (GimpContext   *context,
+                                  GFile         *file,
+                                  GInputStream  *input,
+                                  GError       **error);
+GList * gimp_pattern_load_pixbuf (GimpContext   *context,
+                                  GFile         *file,
+                                  GInputStream  *input,
+                                  GError       **error);
+
+
+#endif /* __GIMP_PATTERN_LOAD_H__ */
diff --git a/app/core/gimppattern-save.c b/app/core/gimppattern-save.c
new file mode 100644
index 0000000..b9ded3e
--- /dev/null
+++ b/app/core/gimppattern-save.c
@@ -0,0 +1,87 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "core-types.h"
+
+#include "gimppattern.h"
+#include "gimppattern-header.h"
+#include "gimppattern-save.h"
+#include "gimptempbuf.h"
+
+#include "gimp-intl.h"
+
+
+gboolean
+gimp_pattern_save (GimpData       *data,
+                   GOutputStream  *output,
+                   GError        **error)
+{
+  GimpPattern       *pattern = GIMP_PATTERN (data);
+  GimpTempBuf       *mask    = gimp_pattern_get_mask (pattern);
+  const Babl        *format  = gimp_temp_buf_get_format (mask);
+  GimpPatternHeader  header;
+  const gchar       *name;
+  gint               width;
+  gint               height;
+
+  name   = gimp_object_get_name (pattern);
+  width  = gimp_temp_buf_get_width  (mask);
+  height = gimp_temp_buf_get_height (mask);
+
+  if (width > GIMP_PATTERN_MAX_SIZE || height > GIMP_PATTERN_MAX_SIZE)
+    {
+      g_set_error (error, GIMP_DATA_ERROR, GIMP_DATA_ERROR_READ,
+                   _("Unsupported pattern dimensions %d x %d.\n"
+                     "GIMP Patterns have a maximum size of %d x %d."),
+                   width, height,
+                   GIMP_PATTERN_MAX_SIZE, GIMP_PATTERN_MAX_SIZE);
+      return FALSE;
+    }
+  header.header_size  = g_htonl (sizeof (GimpPatternHeader) +
+                                 strlen (name) + 1);
+  header.version      = g_htonl (1);
+  header.width        = g_htonl (width);
+  header.height       = g_htonl (height);
+  header.bytes        = g_htonl (babl_format_get_bytes_per_pixel (format));
+  header.magic_number = g_htonl (GIMP_PATTERN_MAGIC);
+
+  if (! g_output_stream_write_all (output, &header, sizeof (header),
+                                   NULL, NULL, error))
+    {
+      return FALSE;
+    }
+
+  if (! g_output_stream_write_all (output, name, strlen (name) + 1,
+                                   NULL, NULL, error))
+    {
+      return FALSE;
+    }
+
+  if (! g_output_stream_write_all (output,
+                                   gimp_temp_buf_get_data (mask),
+                                   gimp_temp_buf_get_data_size (mask),
+                                   NULL, NULL, error))
+    {
+      return FALSE;
+    }
+
+  return TRUE;
+}
diff --git a/app/core/gimppattern-save.h b/app/core/gimppattern-save.h
new file mode 100644
index 0000000..d3c657c
--- /dev/null
+++ b/app/core/gimppattern-save.h
@@ -0,0 +1,28 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_PATTERN_SAVE_H__
+#define __GIMP_PATTERN_SAVE_H__
+
+
+/*  don't call this function directly, use gimp_data_save() instead  */
+gboolean   gimp_pattern_save (GimpData       *data,
+                              GOutputStream  *output,
+                              GError        **error);
+
+
+#endif  /*  __GIMP_PATTERN_SAVE_H__  */
diff --git a/app/core/gimppattern.c b/app/core/gimppattern.c
new file mode 100644
index 0000000..3177211
--- /dev/null
+++ b/app/core/gimppattern.c
@@ -0,0 +1,287 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+
+#include "core-types.h"
+
+#include "gegl/gimp-gegl-loops.h"
+
+#include "gimppattern.h"
+#include "gimppattern-load.h"
+#include "gimppattern-save.h"
+#include "gimptagged.h"
+#include "gimptempbuf.h"
+
+#include "gimp-intl.h"
+
+
+static void          gimp_pattern_tagged_iface_init (GimpTaggedInterface  *iface);
+static void          gimp_pattern_finalize          (GObject              *object);
+
+static gint64        gimp_pattern_get_memsize       (GimpObject           *object,
+                                                     gint64               *gui_size);
+
+static gboolean      gimp_pattern_get_size          (GimpViewable         *viewable,
+                                                     gint                 *width,
+                                                     gint                 *height);
+static GimpTempBuf * gimp_pattern_get_new_preview   (GimpViewable         *viewable,
+                                                     GimpContext          *context,
+                                                     gint                  width,
+                                                     gint                  height);
+static gchar       * gimp_pattern_get_description   (GimpViewable         *viewable,
+                                                     gchar               **tooltip);
+
+static const gchar * gimp_pattern_get_extension     (GimpData             *data);
+static void          gimp_pattern_copy              (GimpData             *data,
+                                                     GimpData             *src_data);
+
+static gchar       * gimp_pattern_get_checksum      (GimpTagged           *tagged);
+
+
+G_DEFINE_TYPE_WITH_CODE (GimpPattern, gimp_pattern, GIMP_TYPE_DATA,
+                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_TAGGED,
+                                                gimp_pattern_tagged_iface_init))
+
+#define parent_class gimp_pattern_parent_class
+
+
+static void
+gimp_pattern_class_init (GimpPatternClass *klass)
+{
+  GObjectClass      *object_class      = G_OBJECT_CLASS (klass);
+  GimpObjectClass   *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+  GimpViewableClass *viewable_class    = GIMP_VIEWABLE_CLASS (klass);
+  GimpDataClass     *data_class        = GIMP_DATA_CLASS (klass);
+
+  object_class->finalize            = gimp_pattern_finalize;
+
+  gimp_object_class->get_memsize    = gimp_pattern_get_memsize;
+
+  viewable_class->default_icon_name = "gimp-tool-bucket-fill";
+  viewable_class->get_size          = gimp_pattern_get_size;
+  viewable_class->get_new_preview   = gimp_pattern_get_new_preview;
+  viewable_class->get_description   = gimp_pattern_get_description;
+
+  data_class->save                  = gimp_pattern_save;
+  data_class->get_extension         = gimp_pattern_get_extension;
+  data_class->copy                  = gimp_pattern_copy;
+}
+
+static void
+gimp_pattern_tagged_iface_init (GimpTaggedInterface *iface)
+{
+  iface->get_checksum = gimp_pattern_get_checksum;
+}
+
+static void
+gimp_pattern_init (GimpPattern *pattern)
+{
+  pattern->mask = NULL;
+}
+
+static void
+gimp_pattern_finalize (GObject *object)
+{
+  GimpPattern *pattern = GIMP_PATTERN (object);
+
+  g_clear_pointer (&pattern->mask, gimp_temp_buf_unref);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static gint64
+gimp_pattern_get_memsize (GimpObject *object,
+                          gint64     *gui_size)
+{
+  GimpPattern *pattern = GIMP_PATTERN (object);
+  gint64       memsize = 0;
+
+  memsize += gimp_temp_buf_get_memsize (pattern->mask);
+
+  return memsize + GIMP_OBJECT_CLASS (parent_class)->get_memsize (object,
+                                                                  gui_size);
+}
+
+static gboolean
+gimp_pattern_get_size (GimpViewable *viewable,
+                       gint         *width,
+                       gint         *height)
+{
+  GimpPattern *pattern = GIMP_PATTERN (viewable);
+
+  *width  = gimp_temp_buf_get_width  (pattern->mask);
+  *height = gimp_temp_buf_get_height (pattern->mask);
+
+  return TRUE;
+}
+
+static GimpTempBuf *
+gimp_pattern_get_new_preview (GimpViewable *viewable,
+                              GimpContext  *context,
+                              gint          width,
+                              gint          height)
+{
+  GimpPattern *pattern = GIMP_PATTERN (viewable);
+  GimpTempBuf *temp_buf;
+  GeglBuffer  *src_buffer;
+  GeglBuffer  *dest_buffer;
+  gint         copy_width;
+  gint         copy_height;
+
+  copy_width  = MIN (width,  gimp_temp_buf_get_width  (pattern->mask));
+  copy_height = MIN (height, gimp_temp_buf_get_height (pattern->mask));
+
+  temp_buf = gimp_temp_buf_new (copy_width, copy_height,
+                                gimp_temp_buf_get_format (pattern->mask));
+
+  src_buffer  = gimp_temp_buf_create_buffer (pattern->mask);
+  dest_buffer = gimp_temp_buf_create_buffer (temp_buf);
+
+  gimp_gegl_buffer_copy (src_buffer,
+                         GEGL_RECTANGLE (0, 0, copy_width, copy_height),
+                         GEGL_ABYSS_NONE,
+                         dest_buffer, GEGL_RECTANGLE (0, 0, 0, 0));
+
+  g_object_unref (src_buffer);
+  g_object_unref (dest_buffer);
+
+  return temp_buf;
+}
+
+static gchar *
+gimp_pattern_get_description (GimpViewable  *viewable,
+                              gchar        **tooltip)
+{
+  GimpPattern *pattern = GIMP_PATTERN (viewable);
+
+  return g_strdup_printf ("%s (%d × %d)",
+                          gimp_object_get_name (pattern),
+                          gimp_temp_buf_get_width  (pattern->mask),
+                          gimp_temp_buf_get_height (pattern->mask));
+}
+
+static const gchar *
+gimp_pattern_get_extension (GimpData *data)
+{
+  return GIMP_PATTERN_FILE_EXTENSION;
+}
+
+static void
+gimp_pattern_copy (GimpData *data,
+                   GimpData *src_data)
+{
+  GimpPattern *pattern     = GIMP_PATTERN (data);
+  GimpPattern *src_pattern = GIMP_PATTERN (src_data);
+
+  g_clear_pointer (&pattern->mask, gimp_temp_buf_unref);
+  pattern->mask = gimp_temp_buf_copy (src_pattern->mask);
+
+  gimp_data_dirty (data);
+}
+
+static gchar *
+gimp_pattern_get_checksum (GimpTagged *tagged)
+{
+  GimpPattern *pattern         = GIMP_PATTERN (tagged);
+  gchar       *checksum_string = NULL;
+
+  if (pattern->mask)
+    {
+      GChecksum *checksum = g_checksum_new (G_CHECKSUM_MD5);
+
+      g_checksum_update (checksum, gimp_temp_buf_get_data (pattern->mask),
+                         gimp_temp_buf_get_data_size (pattern->mask));
+
+      checksum_string = g_strdup (g_checksum_get_string (checksum));
+
+      g_checksum_free (checksum);
+    }
+
+  return checksum_string;
+}
+
+GimpData *
+gimp_pattern_new (GimpContext *context,
+                  const gchar *name)
+{
+  GimpPattern *pattern;
+  guchar      *data;
+  gint         row, col;
+
+  g_return_val_if_fail (name != NULL, NULL);
+  g_return_val_if_fail (name[0] != '\n', NULL);
+
+  pattern = g_object_new (GIMP_TYPE_PATTERN,
+                          "name", name,
+                          NULL);
+
+  pattern->mask = gimp_temp_buf_new (32, 32, babl_format ("R'G'B' u8"));
+
+  data = gimp_temp_buf_get_data (pattern->mask);
+
+  for (row = 0; row < gimp_temp_buf_get_height (pattern->mask); row++)
+    for (col = 0; col < gimp_temp_buf_get_width (pattern->mask); col++)
+      {
+        memset (data, (col % 2) && (row % 2) ? 255 : 0, 3);
+        data += 3;
+      }
+
+  return GIMP_DATA (pattern);
+}
+
+GimpData *
+gimp_pattern_get_standard (GimpContext *context)
+{
+  static GimpData *standard_pattern = NULL;
+
+  if (! standard_pattern)
+    {
+      standard_pattern = gimp_pattern_new (context, "Standard");
+
+      gimp_data_clean (standard_pattern);
+      gimp_data_make_internal (standard_pattern, "gimp-pattern-standard");
+
+      g_object_add_weak_pointer (G_OBJECT (standard_pattern),
+                                 (gpointer *) &standard_pattern);
+    }
+
+  return standard_pattern;
+}
+
+GimpTempBuf *
+gimp_pattern_get_mask (GimpPattern *pattern)
+{
+  g_return_val_if_fail (GIMP_IS_PATTERN (pattern), NULL);
+
+  return pattern->mask;
+}
+
+GeglBuffer *
+gimp_pattern_create_buffer (GimpPattern *pattern)
+{
+  g_return_val_if_fail (GIMP_IS_PATTERN (pattern), NULL);
+
+  return gimp_temp_buf_create_buffer (pattern->mask);
+}
diff --git a/app/core/gimppattern.h b/app/core/gimppattern.h
new file mode 100644
index 0000000..14cc099
--- /dev/null
+++ b/app/core/gimppattern.h
@@ -0,0 +1,58 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_PATTERN_H__
+#define __GIMP_PATTERN_H__
+
+
+#include "gimpdata.h"
+
+
+#define GIMP_TYPE_PATTERN            (gimp_pattern_get_type ())
+#define GIMP_PATTERN(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_PATTERN, GimpPattern))
+#define GIMP_PATTERN_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_PATTERN, GimpPatternClass))
+#define GIMP_IS_PATTERN(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_PATTERN))
+#define GIMP_IS_PATTERN_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_PATTERN))
+#define GIMP_PATTERN_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_PATTERN, GimpPatternClass))
+
+
+typedef struct _GimpPatternClass GimpPatternClass;
+
+struct _GimpPattern
+{
+  GimpData     parent_instance;
+
+  GimpTempBuf *mask;
+};
+
+struct _GimpPatternClass
+{
+  GimpDataClass  parent_class;
+};
+
+
+GType         gimp_pattern_get_type      (void) G_GNUC_CONST;
+
+GimpData    * gimp_pattern_new           (GimpContext *context,
+                                          const gchar *name);
+GimpData    * gimp_pattern_get_standard  (GimpContext *context);
+
+GimpTempBuf * gimp_pattern_get_mask      (GimpPattern *pattern);
+GeglBuffer  * gimp_pattern_create_buffer (GimpPattern *pattern);
+
+
+#endif /* __GIMP_PATTERN_H__ */
diff --git a/app/core/gimppatternclipboard.c b/app/core/gimppatternclipboard.c
new file mode 100644
index 0000000..9dd6a1f
--- /dev/null
+++ b/app/core/gimppatternclipboard.c
@@ -0,0 +1,213 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimppatternclipboard.c
+ * Copyright (C) 2006 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gimp.h"
+#include "gimpbuffer.h"
+#include "gimppatternclipboard.h"
+#include "gimpimage.h"
+#include "gimppickable.h"
+#include "gimptempbuf.h"
+
+#include "gimp-intl.h"
+
+
+#define PATTERN_MAX_SIZE 1024
+
+enum
+{
+  PROP_0,
+  PROP_GIMP
+};
+
+
+/*  local function prototypes  */
+
+static void       gimp_pattern_clipboard_constructed  (GObject      *object);
+static void       gimp_pattern_clipboard_set_property (GObject      *object,
+                                                       guint         property_id,
+                                                       const GValue *value,
+                                                       GParamSpec   *pspec);
+static void       gimp_pattern_clipboard_get_property (GObject      *object,
+                                                       guint         property_id,
+                                                       GValue       *value,
+                                                       GParamSpec   *pspec);
+static GimpData * gimp_pattern_clipboard_duplicate    (GimpData     *data);
+
+static void       gimp_pattern_clipboard_changed      (Gimp         *gimp,
+                                                       GimpPattern  *pattern);
+
+
+G_DEFINE_TYPE (GimpPatternClipboard, gimp_pattern_clipboard, GIMP_TYPE_PATTERN)
+
+#define parent_class gimp_pattern_clipboard_parent_class
+
+
+static void
+gimp_pattern_clipboard_class_init (GimpPatternClipboardClass *klass)
+{
+  GObjectClass  *object_class = G_OBJECT_CLASS (klass);
+  GimpDataClass *data_class   = GIMP_DATA_CLASS (klass);
+
+  object_class->constructed  = gimp_pattern_clipboard_constructed;
+  object_class->set_property = gimp_pattern_clipboard_set_property;
+  object_class->get_property = gimp_pattern_clipboard_get_property;
+
+  data_class->duplicate      = gimp_pattern_clipboard_duplicate;
+
+  g_object_class_install_property (object_class, PROP_GIMP,
+                                   g_param_spec_object ("gimp", NULL, NULL,
+                                                        GIMP_TYPE_GIMP,
+                                                        GIMP_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT_ONLY));
+}
+
+static void
+gimp_pattern_clipboard_init (GimpPatternClipboard *pattern)
+{
+}
+
+static void
+gimp_pattern_clipboard_constructed (GObject *object)
+{
+  GimpPatternClipboard *pattern = GIMP_PATTERN_CLIPBOARD (object);
+
+  G_OBJECT_CLASS (parent_class)->constructed (object);
+
+  gimp_assert (GIMP_IS_GIMP (pattern->gimp));
+
+  g_signal_connect_object (pattern->gimp, "clipboard-changed",
+                           G_CALLBACK (gimp_pattern_clipboard_changed),
+                           pattern, 0);
+
+  gimp_pattern_clipboard_changed (pattern->gimp, GIMP_PATTERN (pattern));
+}
+
+static void
+gimp_pattern_clipboard_set_property (GObject      *object,
+                                     guint         property_id,
+                                     const GValue *value,
+                                     GParamSpec   *pspec)
+{
+  GimpPatternClipboard *pattern = GIMP_PATTERN_CLIPBOARD (object);
+
+  switch (property_id)
+    {
+    case PROP_GIMP:
+      pattern->gimp = g_value_get_object (value);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_pattern_clipboard_get_property (GObject    *object,
+                                     guint       property_id,
+                                     GValue     *value,
+                                     GParamSpec *pspec)
+{
+  GimpPatternClipboard *pattern = GIMP_PATTERN_CLIPBOARD (object);
+
+  switch (property_id)
+    {
+    case PROP_GIMP:
+      g_value_set_object (value, pattern->gimp);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static GimpData *
+gimp_pattern_clipboard_duplicate (GimpData *data)
+{
+  GimpData *new = g_object_new (GIMP_TYPE_PATTERN, NULL);
+
+  gimp_data_copy (new, data);
+
+  return new;
+}
+
+GimpData *
+gimp_pattern_clipboard_new (Gimp *gimp)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  return g_object_new (GIMP_TYPE_PATTERN_CLIPBOARD,
+                       "name", _("Clipboard Image"),
+                       "gimp", gimp,
+                       NULL);
+}
+
+
+/*  private functions  */
+
+static void
+gimp_pattern_clipboard_changed (Gimp        *gimp,
+                                GimpPattern *pattern)
+{
+  GimpObject *paste;
+  GeglBuffer *buffer = NULL;
+
+  g_clear_pointer (&pattern->mask, gimp_temp_buf_unref);
+
+  paste = gimp_get_clipboard_object (gimp);
+
+  if (GIMP_IS_IMAGE (paste))
+    {
+      gimp_pickable_flush (GIMP_PICKABLE (paste));
+      buffer = gimp_pickable_get_buffer (GIMP_PICKABLE (paste));
+    }
+  else if (GIMP_IS_BUFFER (paste))
+    {
+      buffer = gimp_buffer_get_buffer (GIMP_BUFFER (paste));
+    }
+
+  if (buffer)
+    {
+      gint width  = MIN (gegl_buffer_get_width  (buffer), PATTERN_MAX_SIZE);
+      gint height = MIN (gegl_buffer_get_height (buffer), PATTERN_MAX_SIZE);
+
+      pattern->mask = gimp_temp_buf_new (width, height,
+                                         gegl_buffer_get_format (buffer));
+
+      gegl_buffer_get (buffer,
+                       GEGL_RECTANGLE (0, 0, width, height), 1.0,
+                       NULL,
+                       gimp_temp_buf_get_data (pattern->mask),
+                       GEGL_AUTO_ROWSTRIDE, GEGL_ABYSS_NONE);
+    }
+  else
+    {
+      pattern->mask = gimp_temp_buf_new (16, 16, babl_format ("R'G'B' u8"));
+      memset (gimp_temp_buf_get_data (pattern->mask), 255, 16 * 16 * 3);
+    }
+
+  gimp_data_dirty (GIMP_DATA (pattern));
+}
diff --git a/app/core/gimppatternclipboard.h b/app/core/gimppatternclipboard.h
new file mode 100644
index 0000000..2707291
--- /dev/null
+++ b/app/core/gimppatternclipboard.h
@@ -0,0 +1,56 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimppatternclipboard.h
+ * Copyright (C) 2006 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_PATTERN_CLIPBOARD_H__
+#define __GIMP_PATTERN_CLIPBOARD_H__
+
+
+#include "gimppattern.h"
+
+
+#define GIMP_TYPE_PATTERN_CLIPBOARD            (gimp_pattern_clipboard_get_type ())
+#define GIMP_PATTERN_CLIPBOARD(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_PATTERN_CLIPBOARD, GimpPatternClipboard))
+#define GIMP_PATTERN_CLIPBOARD_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_PATTERN_CLIPBOARD, GimpPatternClipboardClass))
+#define GIMP_IS_PATTERN_CLIPBOARD(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_PATTERN_CLIPBOARD))
+#define GIMP_IS_PATTERN_CLIPBOARD_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_PATTERN_CLIPBOARD))
+#define GIMP_PATTERN_CLIPBOARD_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_PATTERN_CLIPBOARD, GimpPatternClipboardClass))
+
+
+typedef struct _GimpPatternClipboardClass GimpPatternClipboardClass;
+
+struct _GimpPatternClipboard
+{
+  GimpPattern  parent_instance;
+
+  Gimp        *gimp;
+};
+
+struct _GimpPatternClipboardClass
+{
+  GimpPatternClass  parent_class;
+};
+
+
+GType      gimp_pattern_clipboard_get_type (void) G_GNUC_CONST;
+
+GimpData * gimp_pattern_clipboard_new      (Gimp *gimp);
+
+
+#endif  /*  __GIMP_PATTERN_CLIPBOARD_H__  */
diff --git a/app/core/gimppdbprogress.c b/app/core/gimppdbprogress.c
new file mode 100644
index 0000000..85147e8
--- /dev/null
+++ b/app/core/gimppdbprogress.c
@@ -0,0 +1,408 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimppdbprogress.c
+ * Copyright (C) 2004 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+
+#include "core-types.h"
+
+#include "core/gimpcontext.h"
+
+#include "pdb/gimppdb.h"
+
+#include "gimp.h"
+#include "gimpparamspecs.h"
+#include "gimppdbprogress.h"
+#include "gimpprogress.h"
+
+#include "gimp-intl.h"
+
+
+enum
+{
+  PROP_0,
+  PROP_PDB,
+  PROP_CONTEXT,
+  PROP_CALLBACK_NAME
+};
+
+
+static void      gimp_pdb_progress_class_init     (GimpPdbProgressClass *klass);
+static void      gimp_pdb_progress_init           (GimpPdbProgress      *progress,
+                                                   GimpPdbProgressClass *klass);
+static void gimp_pdb_progress_progress_iface_init (GimpProgressInterface *iface);
+
+static void      gimp_pdb_progress_constructed    (GObject            *object);
+static void      gimp_pdb_progress_dispose        (GObject            *object);
+static void      gimp_pdb_progress_finalize       (GObject            *object);
+static void      gimp_pdb_progress_set_property   (GObject            *object,
+                                                   guint               property_id,
+                                                   const GValue       *value,
+                                                   GParamSpec         *pspec);
+
+static GimpProgress * gimp_pdb_progress_progress_start   (GimpProgress *progress,
+                                                          gboolean      cancellable,
+                                                          const gchar  *message);
+static void     gimp_pdb_progress_progress_end           (GimpProgress *progress);
+static gboolean gimp_pdb_progress_progress_is_active     (GimpProgress *progress);
+static void     gimp_pdb_progress_progress_set_text      (GimpProgress *progress,
+                                                          const gchar  *message);
+static void     gimp_pdb_progress_progress_set_value     (GimpProgress *progress,
+                                                          gdouble       percentage);
+static gdouble  gimp_pdb_progress_progress_get_value     (GimpProgress *progress);
+static void     gimp_pdb_progress_progress_pulse         (GimpProgress *progress);
+static guint32  gimp_pdb_progress_progress_get_window_id (GimpProgress *progress);
+
+
+static GObjectClass *parent_class = NULL;
+
+
+GType
+gimp_pdb_progress_get_type (void)
+{
+  static GType type = 0;
+
+  if (! type)
+    {
+      const GTypeInfo info =
+      {
+        sizeof (GimpPdbProgressClass),
+        (GBaseInitFunc) NULL,
+        (GBaseFinalizeFunc) NULL,
+        (GClassInitFunc) gimp_pdb_progress_class_init,
+        NULL,           /* class_finalize */
+        NULL,           /* class_data     */
+        sizeof (GimpPdbProgress),
+        0,              /* n_preallocs    */
+        (GInstanceInitFunc) gimp_pdb_progress_init,
+      };
+
+      const GInterfaceInfo progress_iface_info =
+      {
+        (GInterfaceInitFunc) gimp_pdb_progress_progress_iface_init,
+        NULL,           /* iface_finalize */
+        NULL            /* iface_data     */
+      };
+
+      type = g_type_register_static (G_TYPE_OBJECT,
+                                     "GimpPdbProgress",
+                                     &info, 0);
+
+      g_type_add_interface_static (type, GIMP_TYPE_PROGRESS,
+                                   &progress_iface_info);
+    }
+
+  return type;
+}
+
+static void
+gimp_pdb_progress_class_init (GimpPdbProgressClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  parent_class = g_type_class_peek_parent (klass);
+
+  object_class->constructed  = gimp_pdb_progress_constructed;
+  object_class->dispose      = gimp_pdb_progress_dispose;
+  object_class->finalize     = gimp_pdb_progress_finalize;
+  object_class->set_property = gimp_pdb_progress_set_property;
+
+  g_object_class_install_property (object_class, PROP_PDB,
+                                   g_param_spec_object ("pdb", NULL, NULL,
+                                                        GIMP_TYPE_PDB,
+                                                        GIMP_PARAM_WRITABLE |
+                                                        G_PARAM_CONSTRUCT_ONLY));
+
+  g_object_class_install_property (object_class, PROP_CONTEXT,
+                                   g_param_spec_object ("context", NULL, NULL,
+                                                        GIMP_TYPE_CONTEXT,
+                                                        GIMP_PARAM_WRITABLE |
+                                                        G_PARAM_CONSTRUCT_ONLY));
+
+  g_object_class_install_property (object_class, PROP_CALLBACK_NAME,
+                                   g_param_spec_string ("callback-name",
+                                                        NULL, NULL,
+                                                        NULL,
+                                                        GIMP_PARAM_WRITABLE |
+                                                        G_PARAM_CONSTRUCT_ONLY));
+}
+
+static void
+gimp_pdb_progress_init (GimpPdbProgress      *progress,
+                        GimpPdbProgressClass *klass)
+{
+  klass->progresses = g_list_prepend (klass->progresses, progress);
+}
+
+static void
+gimp_pdb_progress_progress_iface_init (GimpProgressInterface *iface)
+{
+  iface->start         = gimp_pdb_progress_progress_start;
+  iface->end           = gimp_pdb_progress_progress_end;
+  iface->is_active     = gimp_pdb_progress_progress_is_active;
+  iface->set_text      = gimp_pdb_progress_progress_set_text;
+  iface->set_value     = gimp_pdb_progress_progress_set_value;
+  iface->get_value     = gimp_pdb_progress_progress_get_value;
+  iface->pulse         = gimp_pdb_progress_progress_pulse;
+  iface->get_window_id = gimp_pdb_progress_progress_get_window_id;
+}
+
+static void
+gimp_pdb_progress_constructed (GObject *object)
+{
+  GimpPdbProgress *progress = GIMP_PDB_PROGRESS (object);
+
+  G_OBJECT_CLASS (parent_class)->constructed (object);
+
+  gimp_assert (GIMP_IS_PDB (progress->pdb));
+  gimp_assert (GIMP_IS_CONTEXT (progress->context));
+}
+
+static void
+gimp_pdb_progress_dispose (GObject *object)
+{
+  GimpPdbProgressClass *klass = GIMP_PDB_PROGRESS_GET_CLASS (object);
+
+  klass->progresses = g_list_remove (klass->progresses, object);
+
+  G_OBJECT_CLASS (parent_class)->dispose (object);
+}
+
+static void
+gimp_pdb_progress_finalize (GObject *object)
+{
+  GimpPdbProgress *progress = GIMP_PDB_PROGRESS (object);
+
+  g_clear_object (&progress->pdb);
+  g_clear_object (&progress->context);
+  g_clear_pointer (&progress->callback_name, g_free);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gimp_pdb_progress_set_property (GObject      *object,
+                                guint         property_id,
+                                const GValue *value,
+                                GParamSpec   *pspec)
+{
+  GimpPdbProgress *progress = GIMP_PDB_PROGRESS (object);
+
+  switch (property_id)
+    {
+    case PROP_PDB:
+      if (progress->pdb)
+        g_object_unref (progress->pdb);
+      progress->pdb = g_value_dup_object (value);
+      break;
+
+    case PROP_CONTEXT:
+      if (progress->context)
+        g_object_unref (progress->context);
+      progress->context = g_value_dup_object (value);
+      break;
+
+    case PROP_CALLBACK_NAME:
+      if (progress->callback_name)
+        g_free (progress->callback_name);
+      progress->callback_name = g_value_dup_string (value);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static gdouble
+gimp_pdb_progress_run_callback (GimpPdbProgress     *progress,
+                                GimpProgressCommand  command,
+                                const gchar         *text,
+                                gdouble              value)
+{
+  gdouble retval = 0;
+
+  if (progress->callback_name && ! progress->callback_busy)
+    {
+      GimpValueArray *return_vals;
+
+      progress->callback_busy = TRUE;
+
+      return_vals =
+        gimp_pdb_execute_procedure_by_name (progress->pdb,
+                                            progress->context,
+                                            NULL, NULL,
+                                            progress->callback_name,
+                                            GIMP_TYPE_INT32, command,
+                                            G_TYPE_STRING,   text,
+                                            G_TYPE_DOUBLE,   value,
+                                            G_TYPE_NONE);
+
+      if (g_value_get_enum (gimp_value_array_index (return_vals, 0)) !=
+          GIMP_PDB_SUCCESS)
+        {
+          gimp_message (progress->context->gimp, NULL, GIMP_MESSAGE_ERROR,
+                        _("Unable to run %s callback. "
+                          "The corresponding plug-in may have crashed."),
+                        g_type_name (G_TYPE_FROM_INSTANCE (progress)));
+        }
+      else if (gimp_value_array_length (return_vals) >= 2 &&
+               G_VALUE_HOLDS_DOUBLE (gimp_value_array_index (return_vals, 1)))
+        {
+          retval = g_value_get_double (gimp_value_array_index (return_vals, 1));
+        }
+
+      gimp_value_array_unref (return_vals);
+
+      progress->callback_busy = FALSE;
+    }
+
+  return retval;
+}
+
+static GimpProgress *
+gimp_pdb_progress_progress_start (GimpProgress *progress,
+                                  gboolean      cancellable,
+                                  const gchar  *message)
+{
+  GimpPdbProgress *pdb_progress = GIMP_PDB_PROGRESS (progress);
+
+  if (! pdb_progress->active)
+    {
+      gimp_pdb_progress_run_callback (pdb_progress,
+                                      GIMP_PROGRESS_COMMAND_START,
+                                      message, 0.0);
+
+      pdb_progress->active = TRUE;
+      pdb_progress->value  = 0.0;
+
+      return progress;
+    }
+
+  return NULL;
+}
+
+static void
+gimp_pdb_progress_progress_end (GimpProgress *progress)
+{
+  GimpPdbProgress *pdb_progress = GIMP_PDB_PROGRESS (progress);
+
+  if (pdb_progress->active)
+    {
+      gimp_pdb_progress_run_callback (pdb_progress,
+                                      GIMP_PROGRESS_COMMAND_END,
+                                      NULL, 0.0);
+
+      pdb_progress->active = FALSE;
+      pdb_progress->value  = 0.0;
+    }
+}
+
+static gboolean
+gimp_pdb_progress_progress_is_active (GimpProgress *progress)
+{
+  GimpPdbProgress *pdb_progress = GIMP_PDB_PROGRESS (progress);
+
+  return pdb_progress->active;
+}
+
+static void
+gimp_pdb_progress_progress_set_text (GimpProgress *progress,
+                                     const gchar  *message)
+{
+  GimpPdbProgress *pdb_progress = GIMP_PDB_PROGRESS (progress);
+
+  if (pdb_progress->active)
+    gimp_pdb_progress_run_callback (pdb_progress,
+                                    GIMP_PROGRESS_COMMAND_SET_TEXT,
+                                    message, 0.0);
+}
+
+static void
+gimp_pdb_progress_progress_set_value (GimpProgress *progress,
+                                      gdouble       percentage)
+{
+  GimpPdbProgress *pdb_progress = GIMP_PDB_PROGRESS (progress);
+
+  if (pdb_progress->active)
+    {
+      gimp_pdb_progress_run_callback (pdb_progress,
+                                      GIMP_PROGRESS_COMMAND_SET_VALUE,
+                                      NULL, percentage);
+      pdb_progress->value = percentage;
+    }
+}
+
+static gdouble
+gimp_pdb_progress_progress_get_value (GimpProgress *progress)
+{
+  GimpPdbProgress *pdb_progress = GIMP_PDB_PROGRESS (progress);
+
+  return pdb_progress->value;
+
+}
+
+static void
+gimp_pdb_progress_progress_pulse (GimpProgress *progress)
+{
+  GimpPdbProgress *pdb_progress = GIMP_PDB_PROGRESS (progress);
+
+  if (pdb_progress->active)
+    gimp_pdb_progress_run_callback (pdb_progress,
+                                    GIMP_PROGRESS_COMMAND_PULSE,
+                                    NULL, 0.0);
+}
+
+static guint32
+gimp_pdb_progress_progress_get_window_id (GimpProgress *progress)
+{
+  GimpPdbProgress *pdb_progress = GIMP_PDB_PROGRESS (progress);
+
+  return (guint32)
+    gimp_pdb_progress_run_callback (pdb_progress,
+                                    GIMP_PROGRESS_COMMAND_GET_WINDOW,
+                                    NULL, 0.0);
+}
+
+GimpPdbProgress *
+gimp_pdb_progress_get_by_callback (GimpPdbProgressClass *klass,
+                                   const gchar          *callback_name)
+{
+  GList *list;
+
+  g_return_val_if_fail (GIMP_IS_PDB_PROGRESS_CLASS (klass), NULL);
+  g_return_val_if_fail (callback_name != NULL, NULL);
+
+  for (list = klass->progresses; list; list = g_list_next (list))
+    {
+      GimpPdbProgress *progress = list->data;
+
+      if (! g_strcmp0 (callback_name, progress->callback_name))
+        return progress;
+    }
+
+  return NULL;
+}
diff --git a/app/core/gimppdbprogress.h b/app/core/gimppdbprogress.h
new file mode 100644
index 0000000..4057332
--- /dev/null
+++ b/app/core/gimppdbprogress.h
@@ -0,0 +1,66 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimppdbprogress.h
+ * Copyright (C) 2004 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_PDB_PROGRESS_H__
+#define __GIMP_PDB_PROGRESS_H__
+
+G_BEGIN_DECLS
+
+
+#define GIMP_TYPE_PDB_PROGRESS            (gimp_pdb_progress_get_type ())
+#define GIMP_PDB_PROGRESS(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_PDB_PROGRESS, GimpPdbProgress))
+#define GIMP_PDB_PROGRESS_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_PDB_PROGRESS, GimpPdbProgressClass))
+#define GIMP_IS_PDB_PROGRESS(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_PDB_PROGRESS))
+#define GIMP_IS_PDB_PROGRESS_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_PDB_PROGRESS))
+#define GIMP_PDB_PROGRESS_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_PDB_PROGRESS, GimpPdbProgressClass))
+
+
+typedef struct _GimpPdbProgressClass  GimpPdbProgressClass;
+
+struct _GimpPdbProgress
+{
+  GObject      object;
+
+  gboolean     active;
+  gdouble      value;
+
+  GimpPDB     *pdb;
+  GimpContext *context;
+  gchar       *callback_name;
+  gboolean     callback_busy;
+};
+
+struct _GimpPdbProgressClass
+{
+  GObjectClass  parent_class;
+
+  GList        *progresses;
+};
+
+
+GType             gimp_pdb_progress_get_type        (void) G_GNUC_CONST;
+
+GimpPdbProgress * gimp_pdb_progress_get_by_callback (GimpPdbProgressClass *klass,
+                                                     const gchar          *callback_name);
+
+
+G_END_DECLS
+
+#endif /* __GIMP_PDB_PROGRESS_H__ */
diff --git a/app/core/gimppickable-auto-shrink.c b/app/core/gimppickable-auto-shrink.c
new file mode 100644
index 0000000..7ddbee2
--- /dev/null
+++ b/app/core/gimppickable-auto-shrink.c
@@ -0,0 +1,312 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gimp.h"
+#include "gimpimage.h"
+#include "gimppickable.h"
+#include "gimppickable-auto-shrink.h"
+
+
+typedef enum
+{
+  AUTO_SHRINK_NOTHING = 0,
+  AUTO_SHRINK_ALPHA   = 1,
+  AUTO_SHRINK_COLOR   = 2
+} AutoShrinkType;
+
+
+typedef gboolean (* ColorsEqualFunc) (guchar *col1,
+                                      guchar *col2);
+
+
+/*  local function prototypes  */
+
+static AutoShrinkType   gimp_pickable_guess_bgcolor (GimpPickable *pickable,
+                                                     guchar       *color,
+                                                     gint          x1,
+                                                     gint          x2,
+                                                     gint          y1,
+                                                     gint          y2);
+static gboolean         gimp_pickable_colors_equal  (guchar       *col1,
+                                                     guchar       *col2);
+static gboolean         gimp_pickable_colors_alpha  (guchar       *col1,
+                                                     guchar       *col2);
+
+
+/*  public functions  */
+
+GimpAutoShrink
+gimp_pickable_auto_shrink (GimpPickable *pickable,
+                           gint          start_x,
+                           gint          start_y,
+                           gint          start_width,
+                           gint          start_height,
+                           gint         *shrunk_x,
+                           gint         *shrunk_y,
+                           gint         *shrunk_width,
+                           gint         *shrunk_height)
+{
+  GeglBuffer      *buffer;
+  GeglRectangle    rect;
+  ColorsEqualFunc  colors_equal_func;
+  guchar           bgcolor[MAX_CHANNELS] = { 0, 0, 0, 0 };
+  guchar          *buf = NULL;
+  gint             x1, y1, x2, y2;
+  gint             width, height;
+  const Babl      *format;
+  gint             x, y, abort;
+  GimpAutoShrink   retval = GIMP_AUTO_SHRINK_UNSHRINKABLE;
+
+  g_return_val_if_fail (GIMP_IS_PICKABLE (pickable), FALSE);
+  g_return_val_if_fail (shrunk_x != NULL, FALSE);
+  g_return_val_if_fail (shrunk_y != NULL, FALSE);
+  g_return_val_if_fail (shrunk_width != NULL, FALSE);
+  g_return_val_if_fail (shrunk_height != NULL, FALSE);
+
+  gimp_set_busy (gimp_pickable_get_image (pickable)->gimp);
+
+  /* You should always keep in mind that x2 and y2 are the NOT the
+   * coordinates of the bottomright corner of the area to be
+   * cropped. They point at the pixel located one to the right and one
+   * to the bottom.
+   */
+
+  gimp_pickable_flush (pickable);
+
+  buffer = gimp_pickable_get_buffer (pickable);
+
+  x1 = MAX (start_x, 0);
+  y1 = MAX (start_y, 0);
+  x2 = MIN (start_x + start_width,  gegl_buffer_get_width  (buffer));
+  y2 = MIN (start_y + start_height, gegl_buffer_get_height (buffer));
+
+  /* By default, return the start values */
+  *shrunk_x      = x1;
+  *shrunk_y      = y1;
+  *shrunk_width  = x2 - x1;
+  *shrunk_height = y2 - y1;
+
+  format = babl_format ("R'G'B'A u8");
+
+  switch (gimp_pickable_guess_bgcolor (pickable, bgcolor,
+                                       x1, x2 - 1, y1, y2 - 1))
+    {
+    case AUTO_SHRINK_ALPHA:
+      colors_equal_func = gimp_pickable_colors_alpha;
+      break;
+    case AUTO_SHRINK_COLOR:
+      colors_equal_func = gimp_pickable_colors_equal;
+      break;
+    default:
+      goto FINISH;
+      break;
+    }
+
+  width  = x2 - x1;
+  height = y2 - y1;
+
+  /* The following could be optimized further by processing
+   * the smaller side first instead of defaulting to width    --Sven
+   */
+
+  buf = g_malloc (MAX (width, height) * 4);
+
+  /* Check how many of the top lines are uniform/transparent. */
+  rect.x      = x1;
+  rect.y      = 0;
+  rect.width  = width;
+  rect.height = 1;
+
+  abort = FALSE;
+  for (y = y1; y < y2 && !abort; y++)
+    {
+      rect.y = y;
+      gegl_buffer_get (buffer, &rect, 1.0, format, buf,
+                       GEGL_AUTO_ROWSTRIDE, GEGL_ABYSS_NONE);
+      for (x = 0; x < width && !abort; x++)
+        abort = ! colors_equal_func (bgcolor, buf + x * 4);
+    }
+  if (y == y2 && !abort)
+    {
+      retval = GIMP_AUTO_SHRINK_EMPTY;
+      goto FINISH;
+    }
+  y1 = y - 1;
+
+  /* Check how many of the bottom lines are uniform/transparent. */
+  rect.x      = x1;
+  rect.y      = 0;
+  rect.width  = width;
+  rect.height = 1;
+
+  abort = FALSE;
+  for (y = y2; y > y1 && !abort; y--)
+    {
+      rect.y = y - 1;
+      gegl_buffer_get (buffer, &rect, 1.0, format, buf,
+                       GEGL_AUTO_ROWSTRIDE, GEGL_ABYSS_NONE);
+      for (x = 0; x < width && !abort; x++)
+        abort = ! colors_equal_func  (bgcolor, buf + x * 4);
+    }
+  y2 = y + 1;
+
+  /* compute a new height for the next operations */
+  height = y2 - y1;
+
+  /* Check how many of the left lines are uniform/transparent. */
+  rect.x      = 0;
+  rect.y      = y1;
+  rect.width  = 1;
+  rect.height = height;
+
+  abort = FALSE;
+  for (x = x1; x < x2 && !abort; x++)
+    {
+      rect.x = x;
+      gegl_buffer_get (buffer, &rect, 1.0, format, buf,
+                       GEGL_AUTO_ROWSTRIDE, GEGL_ABYSS_NONE);
+      for (y = 0; y < height && !abort; y++)
+        abort = ! colors_equal_func (bgcolor, buf + y * 4);
+    }
+  x1 = x - 1;
+
+  /* Check how many of the right lines are uniform/transparent. */
+  rect.x      = 0;
+  rect.y      = y1;
+  rect.width  = 1;
+  rect.height = height;
+
+  abort = FALSE;
+  for (x = x2; x > x1 && !abort; x--)
+    {
+      rect.x = x - 1;
+      gegl_buffer_get (buffer, &rect, 1.0, format, buf,
+                       GEGL_AUTO_ROWSTRIDE, GEGL_ABYSS_NONE);
+      for (y = 0; y < height && !abort; y++)
+        abort = ! colors_equal_func (bgcolor, buf + y * 4);
+    }
+  x2 = x + 1;
+
+  if (x1      != start_x     ||
+      y1      != start_y     ||
+      x2 - x1 != start_width ||
+      y2 - y1 != start_height)
+    {
+      *shrunk_x      = x1;
+      *shrunk_y      = y1;
+      *shrunk_width  = x2 - x1;
+      *shrunk_height = y2 - y1;
+
+      retval = GIMP_AUTO_SHRINK_SHRINK;
+    }
+
+ FINISH:
+
+  g_free (buf);
+  gimp_unset_busy (gimp_pickable_get_image (pickable)->gimp);
+
+  return retval;
+}
+
+
+/*  private functions  */
+
+static AutoShrinkType
+gimp_pickable_guess_bgcolor (GimpPickable *pickable,
+                             guchar       *color,
+                             gint          x1,
+                             gint          x2,
+                             gint          y1,
+                             gint          y2)
+{
+  const Babl *format = babl_format ("R'G'B'A u8");
+  guchar      tl[4];
+  guchar      tr[4];
+  guchar      bl[4];
+  guchar      br[4];
+  gint        i;
+
+  for (i = 0; i < 4; i++)
+    color[i] = 0;
+
+  /* First check if there's transparency to crop. If not, guess the
+   * background-color to see if at least 2 corners are equal.
+   */
+
+  if (! gimp_pickable_get_pixel_at (pickable, x1, y1, format, tl) ||
+      ! gimp_pickable_get_pixel_at (pickable, x1, y2, format, tr) ||
+      ! gimp_pickable_get_pixel_at (pickable, x2, y1, format, bl) ||
+      ! gimp_pickable_get_pixel_at (pickable, x2, y2, format, br))
+    {
+      return AUTO_SHRINK_NOTHING;
+    }
+
+  if ((tl[ALPHA] == 0 && tr[ALPHA] == 0) ||
+      (tl[ALPHA] == 0 && bl[ALPHA] == 0) ||
+      (tr[ALPHA] == 0 && br[ALPHA] == 0) ||
+      (bl[ALPHA] == 0 && br[ALPHA] == 0))
+    {
+      return AUTO_SHRINK_ALPHA;
+    }
+
+  if (gimp_pickable_colors_equal (tl, tr) ||
+      gimp_pickable_colors_equal (tl, bl))
+    {
+      memcpy (color, tl, 4);
+      return AUTO_SHRINK_COLOR;
+    }
+
+  if (gimp_pickable_colors_equal (br, bl) ||
+      gimp_pickable_colors_equal (br, tr))
+    {
+      memcpy (color, br, 4);
+      return AUTO_SHRINK_COLOR;
+    }
+
+  return AUTO_SHRINK_NOTHING;
+}
+
+static gboolean
+gimp_pickable_colors_equal (guchar *col1,
+                            guchar *col2)
+{
+  gint b;
+
+  for (b = 0; b < 4; b++)
+    {
+      if (col1[b] != col2[b])
+        return FALSE;
+    }
+
+  return TRUE;
+}
+
+static gboolean
+gimp_pickable_colors_alpha (guchar *dummy,
+                            guchar *col)
+{
+  return (col[ALPHA] == 0);
+}
diff --git a/app/core/gimppickable-auto-shrink.h b/app/core/gimppickable-auto-shrink.h
new file mode 100644
index 0000000..2f2eaa0
--- /dev/null
+++ b/app/core/gimppickable-auto-shrink.h
@@ -0,0 +1,41 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_PICKABLE_AUTO_SHRINK_H__
+#define __GIMP_PICKABLE_AUTO_SHRINK_H__
+
+
+typedef enum
+{
+  GIMP_AUTO_SHRINK_SHRINK,
+  GIMP_AUTO_SHRINK_EMPTY,
+  GIMP_AUTO_SHRINK_UNSHRINKABLE
+} GimpAutoShrink;
+
+
+GimpAutoShrink   gimp_pickable_auto_shrink (GimpPickable *pickable,
+                                            gint         x,
+                                            gint         y,
+                                            gint         width,
+                                            gint         height,
+                                            gint        *shrunk_x,
+                                            gint        *shrunk_y,
+                                            gint        *shrunk_width,
+                                            gint        *shrunk_height);
+
+
+#endif  /* __GIMP_PICKABLE_AUTO_SHRINK_H__ */
diff --git a/app/core/gimppickable-contiguous-region.cc b/app/core/gimppickable-contiguous-region.cc
new file mode 100644
index 0000000..ea30d0c
--- /dev/null
+++ b/app/core/gimppickable-contiguous-region.cc
@@ -0,0 +1,1123 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <stdlib.h>
+
+#include <cairo.h>
+#include <gegl.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "libgimpcolor/gimpcolor.h"
+#include "libgimpmath/gimpmath.h"
+
+extern "C"
+{
+
+#include "core-types.h"
+
+#include "gegl/gimp-babl.h"
+
+#include "gimp-parallel.h"
+#include "gimp-utils.h" /* GIMP_TIMER */
+#include "gimpasync.h"
+#include "gimplineart.h"
+#include "gimppickable.h"
+#include "gimppickable-contiguous-region.h"
+
+
+#define EPSILON 1e-6
+
+#define PIXELS_PER_THREAD \
+  (/* each thread costs as much as */ 64.0 * 64.0 /* pixels */)
+
+
+typedef struct
+{
+  gint   x;
+  gint   y;
+  gint   level;
+} BorderPixel;
+
+
+/*  local function prototypes  */
+
+static const Babl * choose_format         (GeglBuffer          *buffer,
+                                           GimpSelectCriterion  select_criterion,
+                                           gint                *n_components,
+                                           gboolean            *has_alpha);
+static gfloat   pixel_difference          (const gfloat        *col1,
+                                           const gfloat        *col2,
+                                           gboolean             antialias,
+                                           gfloat               threshold,
+                                           gint                 n_components,
+                                           gboolean             has_alpha,
+                                           gboolean             select_transparent,
+                                           GimpSelectCriterion  select_criterion);
+static void     push_segment              (GQueue              *segment_queue,
+                                           gint                 y,
+                                           gint                 old_y,
+                                           gint                 start,
+                                           gint                 end,
+                                           gint                 new_y,
+                                           gint                 new_start,
+                                           gint                 new_end);
+static void     pop_segment               (GQueue              *segment_queue,
+                                           gint                *y,
+                                           gint                *old_y,
+                                           gint                *start,
+                                           gint                *end);
+static gboolean find_contiguous_segment   (const gfloat        *col,
+                                           GeglBuffer          *src_buffer,
+                                           GeglSampler         *src_sampler,
+                                           const GeglRectangle *src_extent,
+                                           GeglBuffer          *mask_buffer,
+                                           const Babl          *src_format,
+                                           const Babl          *mask_format,
+                                           gint                 n_components,
+                                           gboolean             has_alpha,
+                                           gboolean             select_transparent,
+                                           GimpSelectCriterion  select_criterion,
+                                           gboolean             antialias,
+                                           gfloat               threshold,
+                                           gint                 initial_x,
+                                           gint                 initial_y,
+                                           gint                *start,
+                                           gint                *end,
+                                           gfloat              *row);
+static void     find_contiguous_region    (GeglBuffer          *src_buffer,
+                                           GeglBuffer          *mask_buffer,
+                                           const Babl          *format,
+                                           gint                 n_components,
+                                           gboolean             has_alpha,
+                                           gboolean             select_transparent,
+                                           GimpSelectCriterion  select_criterion,
+                                           gboolean             antialias,
+                                           gfloat               threshold,
+                                           gboolean             diagonal_neighbors,
+                                           gint                 x,
+                                           gint                 y,
+                                           const gfloat        *col);
+
+static void            line_art_queue_pixel (GQueue              *queue,
+                                             gint                 x,
+                                             gint                 y,
+                                             gint                 level);
+
+
+/*  public functions  */
+
+GeglBuffer *
+gimp_pickable_contiguous_region_by_seed (GimpPickable        *pickable,
+                                         gboolean             antialias,
+                                         gfloat               threshold,
+                                         gboolean             select_transparent,
+                                         GimpSelectCriterion  select_criterion,
+                                         gboolean             diagonal_neighbors,
+                                         gint                 x,
+                                         gint                 y)
+{
+  GeglBuffer    *src_buffer;
+  GeglBuffer    *mask_buffer;
+  const Babl    *format;
+  GeglRectangle  extent;
+  gint           n_components;
+  gboolean       has_alpha;
+  gfloat         start_col[MAX_CHANNELS];
+
+  g_return_val_if_fail (GIMP_IS_PICKABLE (pickable), NULL);
+
+  gimp_pickable_flush (pickable);
+  src_buffer = gimp_pickable_get_buffer (pickable);
+
+  format = choose_format (src_buffer, select_criterion,
+                          &n_components, &has_alpha);
+  gegl_buffer_sample (src_buffer, x, y, NULL, start_col, format,
+                      GEGL_SAMPLER_NEAREST, GEGL_ABYSS_NONE);
+
+  if (has_alpha)
+    {
+      if (select_transparent)
+        {
+          /*  don't select transparent regions if the start pixel isn't
+           *  fully transparent
+           */
+          if (start_col[n_components - 1] > 0)
+            select_transparent = FALSE;
+        }
+    }
+  else
+    {
+      select_transparent = FALSE;
+    }
+
+  extent = *gegl_buffer_get_extent (src_buffer);
+
+  mask_buffer = gegl_buffer_new (&extent, babl_format ("Y float"));
+
+  if (x >= extent.x && x < (extent.x + extent.width) &&
+      y >= extent.y && y < (extent.y + extent.height))
+    {
+      GIMP_TIMER_START();
+
+      find_contiguous_region (src_buffer, mask_buffer,
+                              format, n_components, has_alpha,
+                              select_transparent, select_criterion,
+                              antialias, threshold, diagonal_neighbors,
+                              x, y, start_col);
+
+      GIMP_TIMER_END("foo");
+    }
+
+  return mask_buffer;
+}
+
+GeglBuffer *
+gimp_pickable_contiguous_region_by_color (GimpPickable        *pickable,
+                                          gboolean             antialias,
+                                          gfloat               threshold,
+                                          gboolean             select_transparent,
+                                          GimpSelectCriterion  select_criterion,
+                                          const GimpRGB       *color)
+{
+  /*  Scan over the pickable's active layer, finding pixels within the
+   *  specified threshold from the given R, G, & B values.  If
+   *  antialiasing is on, use the same antialiasing scheme as in
+   *  fuzzy_select.  Modify the pickable's mask to reflect the
+   *  additional selection
+   */
+  GeglBuffer *src_buffer;
+  GeglBuffer *mask_buffer;
+  const Babl *format;
+  gint        n_components;
+  gboolean    has_alpha;
+  gfloat      start_col[MAX_CHANNELS];
+
+  g_return_val_if_fail (GIMP_IS_PICKABLE (pickable), NULL);
+  g_return_val_if_fail (color != NULL, NULL);
+
+  /* increase the threshold by EPSILON, to allow for conversion errors,
+   * especially when threshold == 0 (see issue #1554.)  we need to do this
+   * here, but not in the other functions, since the input color gets converted
+   * to the format in which we perform the comparison through a different path
+   * than the pickable's pixels, which can introduce error.
+   */
+  threshold += EPSILON;
+
+  gimp_pickable_flush (pickable);
+
+  src_buffer = gimp_pickable_get_buffer (pickable);
+
+  format = choose_format (src_buffer, select_criterion,
+                          &n_components, &has_alpha);
+
+  gimp_rgba_get_pixel (color, format, start_col);
+
+  if (has_alpha)
+    {
+      if (select_transparent)
+        {
+          /*  don't select transparency if "color" isn't fully transparent
+           */
+          if (start_col[n_components - 1] > 0.0)
+            select_transparent = FALSE;
+        }
+    }
+  else
+    {
+      select_transparent = FALSE;
+    }
+
+  mask_buffer = gegl_buffer_new (gegl_buffer_get_extent (src_buffer),
+                                 babl_format ("Y float"));
+
+  gegl_parallel_distribute_area (
+    gegl_buffer_get_extent (src_buffer), PIXELS_PER_THREAD,
+    [=] (const GeglRectangle *area)
+    {
+      GeglBufferIterator *iter;
+
+      iter = gegl_buffer_iterator_new (src_buffer,
+                                       area, 0, format,
+                                       GEGL_ACCESS_READ, GEGL_ABYSS_NONE, 2);
+
+      gegl_buffer_iterator_add (iter, mask_buffer,
+                                area, 0, babl_format ("Y float"),
+                                GEGL_ACCESS_WRITE, GEGL_ABYSS_NONE);
+
+      while (gegl_buffer_iterator_next (iter))
+        {
+          const gfloat *src   = (const gfloat *) iter->items[0].data;
+          gfloat       *dest  = (      gfloat *) iter->items[1].data;
+          gint          count = iter->length;
+
+          while (count--)
+            {
+              /*  Find how closely the colors match  */
+              *dest = pixel_difference (start_col, src,
+                                        antialias,
+                                        threshold,
+                                        n_components,
+                                        has_alpha,
+                                        select_transparent,
+                                        select_criterion);
+
+              src  += n_components;
+              dest += 1;
+            }
+        }
+    });
+
+  return mask_buffer;
+}
+
+GeglBuffer *
+gimp_pickable_contiguous_region_by_line_art (GimpPickable *pickable,
+                                             GimpLineArt  *line_art,
+                                             gint          x,
+                                             gint          y)
+{
+  GeglBuffer    *src_buffer;
+  GeglBuffer    *mask_buffer;
+  const Babl    *format  = babl_format ("Y float");
+  gfloat        *distmap = NULL;
+  GeglRectangle  extent;
+  gboolean       free_line_art = FALSE;
+  gboolean       filled        = FALSE;
+  guchar         start_col;
+
+  g_return_val_if_fail (GIMP_IS_PICKABLE (pickable) || GIMP_IS_LINE_ART (line_art), NULL);
+
+  if (! line_art)
+    {
+      /* It is much better experience to pre-compute the line art,
+       * but it may not be always possible (for instance when
+       * selecting/filling through a PDB call).
+       */
+      line_art = gimp_line_art_new ();
+      gimp_line_art_set_input (line_art, pickable);
+      free_line_art = TRUE;
+    }
+
+  src_buffer = gimp_line_art_get (line_art, &distmap);
+  g_return_val_if_fail (src_buffer && distmap, NULL);
+
+  gegl_buffer_sample (src_buffer, x, y, NULL, &start_col, NULL,
+                      GEGL_SAMPLER_NEAREST, GEGL_ABYSS_NONE);
+
+  extent = *gegl_buffer_get_extent (src_buffer);
+
+  mask_buffer = gegl_buffer_new (&extent, format);
+
+  if (start_col)
+    {
+      if (start_col == 1)
+        {
+          /* As a special exception, if you fill over a line art pixel, only
+           * fill the pixel and exit
+           */
+          gfloat col = 1.0;
+
+          gegl_buffer_set (mask_buffer, GEGL_RECTANGLE (x, y, 1, 1),
+                           0, format, &col, GEGL_AUTO_ROWSTRIDE);
+        }
+      else /* start_col == 2 */
+        {
+          /* If you fill over a closure pixel, let's fill on all sides
+           * of the start point. Otherwise we get a very weird result
+           * with only a single pixel filled in the middle of an empty
+           * region (since closure pixels are invisible by nature).
+           */
+          gfloat col = 0.0;
+
+          if (x - 1 >= extent.x && x - 1 < extent.x + extent.width &&
+              y - 1 >= extent.y && y - 1 < (extent.y + extent.height))
+            find_contiguous_region (src_buffer, mask_buffer,
+                                    format, 1, FALSE,
+                                    FALSE, GIMP_SELECT_CRITERION_COMPOSITE,
+                                    FALSE, 0.0, FALSE,
+                                    x - 1, y - 1, &col);
+          if (x - 1 >= extent.x && x - 1 < extent.x + extent.width &&
+              y >= extent.y && y < (extent.y + extent.height))
+            find_contiguous_region (src_buffer, mask_buffer,
+                                    format, 1, FALSE,
+                                    FALSE, GIMP_SELECT_CRITERION_COMPOSITE,
+                                    FALSE, 0.0, FALSE,
+                                    x - 1, y, &col);
+          if (x - 1 >= extent.x && x - 1 < extent.x + extent.width &&
+              y + 1 >= extent.y && y + 1 < (extent.y + extent.height))
+            find_contiguous_region (src_buffer, mask_buffer,
+                                    format, 1, FALSE,
+                                    FALSE, GIMP_SELECT_CRITERION_COMPOSITE,
+                                    FALSE, 0.0, FALSE,
+                                    x - 1, y + 1, &col);
+          if (x >= extent.x && x < extent.x + extent.width &&
+              y - 1 >= extent.y && y - 1 < (extent.y + extent.height))
+            find_contiguous_region (src_buffer, mask_buffer,
+                                    format, 1, FALSE,
+                                    FALSE, GIMP_SELECT_CRITERION_COMPOSITE,
+                                    FALSE, 0.0, FALSE,
+                                    x, y - 1, &col);
+          if (x >= extent.x && x < extent.x + extent.width &&
+              y + 1 >= extent.y && y + 1 < (extent.y + extent.height))
+            find_contiguous_region (src_buffer, mask_buffer,
+                                    format, 1, FALSE,
+                                    FALSE, GIMP_SELECT_CRITERION_COMPOSITE,
+                                    FALSE, 0.0, FALSE,
+                                    x, y + 1, &col);
+          if (x + 1 >= extent.x && x + 1 < extent.x + extent.width &&
+              y - 1 >= extent.y && y - 1 < (extent.y + extent.height))
+            find_contiguous_region (src_buffer, mask_buffer,
+                                    format, 1, FALSE,
+                                    FALSE, GIMP_SELECT_CRITERION_COMPOSITE,
+                                    FALSE, 0.0, FALSE,
+                                    x + 1, y - 1, &col);
+          if (x + 1 >= extent.x && x + 1 < extent.x + extent.width &&
+              y >= extent.y && y < (extent.y + extent.height))
+            find_contiguous_region (src_buffer, mask_buffer,
+                                    format, 1, FALSE,
+                                    FALSE, GIMP_SELECT_CRITERION_COMPOSITE,
+                                    FALSE, 0.0, FALSE,
+                                    x + 1, y, &col);
+          if (x + 1 >= extent.x && x + 1 < extent.x + extent.width &&
+              y + 1 >= extent.y && y + 1 < (extent.y + extent.height))
+            find_contiguous_region (src_buffer, mask_buffer,
+                                    format, 1, FALSE,
+                                    FALSE, GIMP_SELECT_CRITERION_COMPOSITE,
+                                    FALSE, 0.0, FALSE,
+                                    x + 1, y + 1, &col);
+          filled = TRUE;
+        }
+    }
+  else if (x >= extent.x && x < (extent.x + extent.width) &&
+           y >= extent.y && y < (extent.y + extent.height))
+    {
+      gfloat col = 0.0;
+
+      find_contiguous_region (src_buffer, mask_buffer,
+                              format, 1, FALSE,
+                              FALSE, GIMP_SELECT_CRITERION_COMPOSITE,
+                              FALSE, 0.0, FALSE,
+                              x, y, &col);
+      filled = TRUE;
+    }
+
+  if (filled)
+    {
+      GQueue *queue  = g_queue_new ();
+      gfloat *mask;
+      gint    width  = gegl_buffer_get_width (src_buffer);
+      gint    height = gegl_buffer_get_height (src_buffer);
+      gint    line_art_max_grow;
+      gint    nx, ny;
+
+      GIMP_TIMER_START();
+      /* The last step of the line art algorithm is to make sure that
+       * selections does not leave "holes" between its borders and the
+       * line arts, while not stepping over as well.
+       * I used to run the "gegl:watershed-transform" operation to flood
+       * the stroke pixels, but for such simple need, this simple code
+       * is so much faster while producing better results.
+       */
+      mask = g_new (gfloat, width * height);
+      gegl_buffer_get (mask_buffer, NULL, 1.0, NULL,
+                       mask, GEGL_AUTO_ROWSTRIDE, GEGL_ABYSS_NONE);
+
+      for (y = 0; y < height; y++)
+        for (x = 0; x < width; x++)
+          {
+            if (distmap[x + y * width] == 1.0)
+              {
+                if (x > 0)
+                  {
+                    nx = x - 1;
+                    if (y > 0)
+                      {
+                        ny = y - 1;
+                        if (mask[nx + ny * width] != 0.0)
+                          {
+                            line_art_queue_pixel (queue, x, y, 1);
+                            continue;
+                          }
+                      }
+                    ny = y;
+                    if (mask[nx + ny * width] != 0.0)
+                      {
+                        line_art_queue_pixel (queue, x, y, 1);
+                        continue;
+                      }
+                    if (y < height - 1)
+                      {
+                        ny = y + 1;
+                        if (mask[nx + ny * width] != 0.0)
+                          {
+                            line_art_queue_pixel (queue, x, y, 1);
+                            continue;
+                          }
+                      }
+                  }
+                if (x < width - 1)
+                  {
+                    nx = x + 1;
+                    if (y > 0)
+                      {
+                        ny = y - 1;
+                        if (mask[nx + ny * width] != 0.0)
+                          {
+                            line_art_queue_pixel (queue, x, y, 1);
+                            continue;
+                          }
+                      }
+                    ny = y;
+                    if (mask[nx + ny * width] != 0.0)
+                      {
+                        line_art_queue_pixel (queue, x, y, 1);
+                        continue;
+                      }
+                    if (y < height - 1)
+                      {
+                        ny = y + 1;
+                        if (mask[nx + ny * width] != 0.0)
+                          {
+                            line_art_queue_pixel (queue, x, y, 1);
+                            continue;
+                          }
+                      }
+                  }
+                nx = x;
+                if (y > 0)
+                  {
+                    ny = y - 1;
+                    if (mask[nx + ny * width] != 0.0)
+                      {
+                        line_art_queue_pixel (queue, x, y, 1);
+                        continue;
+                      }
+                  }
+                if (y < height - 1)
+                  {
+                    ny = y + 1;
+                    if (mask[nx + ny * width] != 0.0)
+                      {
+                        line_art_queue_pixel (queue, x, y, 1);
+                        continue;
+                      }
+                  }
+              }
+          }
+
+      g_object_get (line_art,
+                    "max-grow", &line_art_max_grow,
+                    NULL);
+      while (! g_queue_is_empty (queue))
+        {
+          BorderPixel *c = (BorderPixel *) g_queue_pop_head (queue);
+
+          if (mask[c->x + c->y * width] != 1.0)
+            {
+              mask[c->x + c->y * width] = 1.0;
+              if (c->level >= line_art_max_grow)
+                /* Do not overflood under line arts. */
+                continue;
+              if (c->x > 0)
+                {
+                  nx = c->x - 1;
+                  if (c->y > 0)
+                    {
+                      ny = c->y - 1;
+                      if (mask[nx + ny * width] == 0.0 &&
+                          distmap[nx + ny * width] > distmap[c->x + c->y * width])
+                        line_art_queue_pixel (queue, nx, ny, c->level + 1);
+                    }
+                  ny = c->y;
+                  if (mask[nx + ny * width] == 0.0 &&
+                      distmap[nx + ny * width] > distmap[c->x + c->y * width])
+                    line_art_queue_pixel (queue, nx, ny, c->level + 1);
+                  if (c->y < height - 1)
+                    {
+                      ny = c->y + 1;
+                      if (mask[nx + ny * width] == 0.0 &&
+                          distmap[nx + ny * width] > distmap[c->x + c->y * width])
+                        line_art_queue_pixel (queue, nx, ny, c->level + 1);
+                    }
+                }
+              if (c->x < width - 1)
+                {
+                  nx = c->x + 1;
+                  if (c->y > 0)
+                    {
+                      ny = c->y - 1;
+                      if (mask[nx + ny * width] == 0.0 &&
+                          distmap[nx + ny * width] > distmap[c->x + c->y * width])
+                        line_art_queue_pixel (queue, nx, ny, c->level + 1);
+                    }
+                  ny = c->y;
+                  if (mask[nx + ny * width] == 0.0 &&
+                      distmap[nx + ny * width] > distmap[c->x + c->y * width])
+                    line_art_queue_pixel (queue, nx, ny, c->level + 1);
+                  if (c->y < height - 1)
+                    {
+                      ny = c->y + 1;
+                      if (mask[nx + ny * width] == 0.0 &&
+                          distmap[nx + ny * width] > distmap[c->x + c->y * width])
+                        line_art_queue_pixel (queue, nx, ny, c->level + 1);
+                    }
+                }
+              nx = c->x;
+              if (c->y > 0)
+                {
+                  ny = c->y - 1;
+                  if (mask[nx + ny * width] == 0.0 &&
+                      distmap[nx + ny * width] > distmap[c->x + c->y * width])
+                    line_art_queue_pixel (queue, nx, ny, c->level + 1);
+                }
+              if (c->y < height - 1)
+                {
+                  ny = c->y + 1;
+                  if (mask[nx + ny * width] == 0.0 &&
+                      distmap[nx + ny * width] > distmap[c->x + c->y * width])
+                    line_art_queue_pixel (queue, nx, ny, c->level + 1);
+                }
+            }
+          g_free (c);
+        }
+      g_queue_free (queue);
+      gegl_buffer_set (mask_buffer, gegl_buffer_get_extent (mask_buffer),
+                       0, NULL, mask, GEGL_AUTO_ROWSTRIDE);
+      g_free (mask);
+
+      GIMP_TIMER_END("watershed line art");
+    }
+  if (free_line_art)
+    g_clear_object (&line_art);
+
+  return mask_buffer;
+}
+
+/*  private functions  */
+
+static const Babl *
+choose_format (GeglBuffer          *buffer,
+               GimpSelectCriterion  select_criterion,
+               gint                *n_components,
+               gboolean            *has_alpha)
+{
+  const Babl *format = gegl_buffer_get_format (buffer);
+
+  *has_alpha = babl_format_has_alpha (format);
+
+  switch (select_criterion)
+    {
+    case GIMP_SELECT_CRITERION_COMPOSITE:
+      if (babl_format_is_palette (format))
+        format = babl_format ("R'G'B'A float");
+      else
+        format = gimp_babl_format (gimp_babl_format_get_base_type (format),
+                                   GIMP_PRECISION_FLOAT_GAMMA,
+                                   *has_alpha);
+      break;
+
+    case GIMP_SELECT_CRITERION_R:
+    case GIMP_SELECT_CRITERION_G:
+    case GIMP_SELECT_CRITERION_B:
+    case GIMP_SELECT_CRITERION_A:
+      format = babl_format ("R'G'B'A float");
+      break;
+
+    case GIMP_SELECT_CRITERION_H:
+    case GIMP_SELECT_CRITERION_S:
+    case GIMP_SELECT_CRITERION_V:
+      format = babl_format ("HSVA float");
+      break;
+
+    case GIMP_SELECT_CRITERION_LCH_L:
+      format = babl_format ("CIE L alpha float");
+      break;
+
+    case GIMP_SELECT_CRITERION_LCH_C:
+    case GIMP_SELECT_CRITERION_LCH_H:
+      format = babl_format ("CIE LCH(ab) alpha float");
+      break;
+
+    default:
+      g_return_val_if_reached (NULL);
+      break;
+    }
+
+  *n_components = babl_format_get_n_components (format);
+
+  return format;
+}
+
+static gfloat
+pixel_difference (const gfloat        *col1,
+                  const gfloat        *col2,
+                  gboolean             antialias,
+                  gfloat               threshold,
+                  gint                 n_components,
+                  gboolean             has_alpha,
+                  gboolean             select_transparent,
+                  GimpSelectCriterion  select_criterion)
+{
+  gfloat max = 0.0;
+
+  /*  if there is an alpha channel, never select transparent regions  */
+  if (! select_transparent && has_alpha && col2[n_components - 1] == 0.0)
+    return 0.0;
+
+  if (select_transparent && has_alpha)
+    {
+      max = fabs (col1[n_components - 1] - col2[n_components - 1]);
+    }
+  else
+    {
+      gfloat diff;
+      gint   b;
+
+      if (has_alpha)
+        n_components--;
+
+      switch (select_criterion)
+        {
+        case GIMP_SELECT_CRITERION_COMPOSITE:
+          for (b = 0; b < n_components; b++)
+            {
+              diff = fabs (col1[b] - col2[b]);
+              if (diff > max)
+                max = diff;
+            }
+          break;
+
+        case GIMP_SELECT_CRITERION_R:
+          max = fabs (col1[0] - col2[0]);
+          break;
+
+        case GIMP_SELECT_CRITERION_G:
+          max = fabs (col1[1] - col2[1]);
+          break;
+
+        case GIMP_SELECT_CRITERION_B:
+          max = fabs (col1[2] - col2[2]);
+          break;
+
+        case GIMP_SELECT_CRITERION_A:
+          max = fabs (col1[3] - col2[3]);
+          break;
+
+        case GIMP_SELECT_CRITERION_H:
+          if (col1[1] > EPSILON)
+            {
+              if (col2[1] > EPSILON)
+                {
+                  max = fabs (col1[0] - col2[0]);
+                  max = MIN (max, 1.0 - max);
+                }
+              else
+                {
+                  /* "infinite" difference.  anything >> 1 will do. */
+                  max = 10.0;
+                }
+            }
+          else
+            {
+              if (col2[1] > EPSILON)
+                {
+                  /* "infinite" difference.  anything >> 1 will do. */
+                  max = 10.0;
+                }
+              else
+                {
+                  max = 0.0;
+                }
+            }
+          break;
+
+        case GIMP_SELECT_CRITERION_S:
+          max = fabs (col1[1] - col2[1]);
+          break;
+
+        case GIMP_SELECT_CRITERION_V:
+          max = fabs (col1[2] - col2[2]);
+          break;
+
+        case GIMP_SELECT_CRITERION_LCH_L:
+          max = fabs (col1[0] - col2[0]) / 100.0;
+          break;
+
+        case GIMP_SELECT_CRITERION_LCH_C:
+          max = fabs (col1[1] - col2[1]) / 100.0;
+          break;
+
+        case GIMP_SELECT_CRITERION_LCH_H:
+          if (col1[1] > 100.0 * EPSILON)
+            {
+              if (col2[1] > 100.0 * EPSILON)
+                {
+                  max = fabs (col1[2] - col2[2]) / 360.0;
+                  max = MIN (max, 1.0 - max);
+                }
+              else
+                {
+                  /* "infinite" difference.  anything >> 1 will do. */
+                  max = 10.0;
+                }
+            }
+          else
+            {
+              if (col2[1] > 100.0 * EPSILON)
+                {
+                  /* "infinite" difference.  anything >> 1 will do. */
+                  max = 10.0;
+                }
+              else
+                {
+                  max = 0.0;
+                }
+            }
+          break;
+        }
+    }
+
+  if (antialias && threshold > 0.0)
+    {
+      gfloat aa = 1.5 - (max / threshold);
+
+      if (aa <= 0.0)
+        return 0.0;
+      else if (aa < 0.5)
+        return aa * 2.0;
+      else
+        return 1.0;
+    }
+  else
+    {
+      if (max > threshold)
+        return 0.0;
+      else
+        return 1.0;
+    }
+}
+
+static void
+push_segment (GQueue *segment_queue,
+              gint    y,
+              gint    old_y,
+              gint    start,
+              gint    end,
+              gint    new_y,
+              gint    new_start,
+              gint    new_end)
+{
+  /* To avoid excessive memory allocation (y, old_y, start, end) tuples are
+   * stored in interleaved format:
+   *
+   * [y1] [old_y1] [start1] [end1] [y2] [old_y2] [start2] [end2]
+   */
+
+  if (new_y != old_y)
+    {
+      /* If the new segment's y-coordinate is different than the old (source)
+       * segment's y-coordinate, push the entire segment.
+       */
+      g_queue_push_tail (segment_queue, GINT_TO_POINTER (new_y));
+      g_queue_push_tail (segment_queue, GINT_TO_POINTER (y));
+      g_queue_push_tail (segment_queue, GINT_TO_POINTER (new_start));
+      g_queue_push_tail (segment_queue, GINT_TO_POINTER (new_end));
+    }
+  else
+    {
+      /* Otherwise, only push the set-difference between the new segment and
+       * the source segment (since we've already scanned the source segment.)
+       * Note that the `+ 1` and `- 1` terms of the end/start coordinates below
+       * are only necessary when `diagonal_neighbors` is on (and otherwise make
+       * the segments slightly larger than necessary), but, meh...
+       */
+      if (new_start < start)
+        {
+          g_queue_push_tail (segment_queue, GINT_TO_POINTER (new_y));
+          g_queue_push_tail (segment_queue, GINT_TO_POINTER (y));
+          g_queue_push_tail (segment_queue, GINT_TO_POINTER (new_start));
+          g_queue_push_tail (segment_queue, GINT_TO_POINTER (start + 1));
+        }
+
+      if (new_end > end)
+        {
+          g_queue_push_tail (segment_queue, GINT_TO_POINTER (new_y));
+          g_queue_push_tail (segment_queue, GINT_TO_POINTER (y));
+          g_queue_push_tail (segment_queue, GINT_TO_POINTER (end - 1));
+          g_queue_push_tail (segment_queue, GINT_TO_POINTER (new_end));
+        }
+    }
+}
+
+static void
+pop_segment (GQueue *segment_queue,
+             gint   *y,
+             gint   *old_y,
+             gint   *start,
+             gint   *end)
+{
+  *y     = GPOINTER_TO_INT (g_queue_pop_head (segment_queue));
+  *old_y = GPOINTER_TO_INT (g_queue_pop_head (segment_queue));
+  *start = GPOINTER_TO_INT (g_queue_pop_head (segment_queue));
+  *end   = GPOINTER_TO_INT (g_queue_pop_head (segment_queue));
+}
+
+/* #define FETCH_ROW 1 */
+
+static gboolean
+find_contiguous_segment (const gfloat        *col,
+                         GeglBuffer          *src_buffer,
+                         GeglSampler         *src_sampler,
+                         const GeglRectangle *src_extent,
+                         GeglBuffer          *mask_buffer,
+                         const Babl          *src_format,
+                         const Babl          *mask_format,
+                         gint                 n_components,
+                         gboolean             has_alpha,
+                         gboolean             select_transparent,
+                         GimpSelectCriterion  select_criterion,
+                         gboolean             antialias,
+                         gfloat               threshold,
+                         gint                 initial_x,
+                         gint                 initial_y,
+                         gint                *start,
+                         gint                *end,
+                         gfloat              *row)
+{
+  gfloat *s;
+  gfloat  mask_row_buf[src_extent->width];
+  gfloat *mask_row = mask_row_buf - src_extent->x;
+  gfloat  diff;
+
+#ifdef FETCH_ROW
+  gegl_buffer_get (src_buffer, GEGL_RECTANGLE (0, initial_y, width, 1), 1.0,
+                   src_format,
+                   row, GEGL_AUTO_ROWSTRIDE, GEGL_ABYSS_NONE);
+  s = row + initial_x * n_components;
+#else
+  s = (gfloat *) g_alloca (n_components * sizeof (gfloat));
+
+  gegl_sampler_get (src_sampler,
+                    initial_x, initial_y, NULL, s, GEGL_ABYSS_NONE);
+#endif
+
+  diff = pixel_difference (col, s, antialias, threshold,
+                           n_components, has_alpha, select_transparent,
+                           select_criterion);
+
+  /* check the starting pixel */
+  if (! diff)
+    return FALSE;
+
+  mask_row[initial_x] = diff;
+
+  *start = initial_x - 1;
+#ifdef FETCH_ROW
+  s = row + *start * n_components;
+#endif
+
+  while (*start >= src_extent->x)
+    {
+#ifndef FETCH_ROW
+      gegl_sampler_get (src_sampler,
+                        *start, initial_y, NULL, s, GEGL_ABYSS_NONE);
+#endif
+
+      diff = pixel_difference (col, s, antialias, threshold,
+                               n_components, has_alpha, select_transparent,
+                               select_criterion);
+      if (diff == 0.0)
+        break;
+
+      mask_row[*start] = diff;
+
+      (*start)--;
+#ifdef FETCH_ROW
+      s -= n_components;
+#endif
+    }
+
+  *end = initial_x + 1;
+#ifdef FETCH_ROW
+  s = row + *end * n_components;
+#endif
+
+  while (*end < src_extent->x + src_extent->width)
+    {
+#ifndef FETCH_ROW
+      gegl_sampler_get (src_sampler,
+                        *end, initial_y, NULL, s, GEGL_ABYSS_NONE);
+#endif
+
+      diff = pixel_difference (col, s, antialias, threshold,
+                               n_components, has_alpha, select_transparent,
+                               select_criterion);
+      if (diff == 0.0)
+        break;
+
+      mask_row[*end] = diff;
+
+      (*end)++;
+#ifdef FETCH_ROW
+      s += n_components;
+#endif
+    }
+
+  gegl_buffer_set (mask_buffer, GEGL_RECTANGLE (*start + 1, initial_y,
+                                                *end - *start - 1, 1),
+                   0, mask_format, &mask_row[*start + 1],
+                   GEGL_AUTO_ROWSTRIDE);
+
+  return TRUE;
+}
+
+static void
+find_contiguous_region (GeglBuffer          *src_buffer,
+                        GeglBuffer          *mask_buffer,
+                        const Babl          *format,
+                        gint                 n_components,
+                        gboolean             has_alpha,
+                        gboolean             select_transparent,
+                        GimpSelectCriterion  select_criterion,
+                        gboolean             antialias,
+                        gfloat               threshold,
+                        gboolean             diagonal_neighbors,
+                        gint                 x,
+                        gint                 y,
+                        const gfloat        *col)
+{
+  const Babl          *mask_format = babl_format ("Y float");
+  GeglSampler         *src_sampler;
+  const GeglRectangle *src_extent;
+  gint                 old_y;
+  gint                 start, end;
+  gint                 new_start, new_end;
+  GQueue              *segment_queue;
+  gfloat              *row = NULL;
+
+  src_extent = gegl_buffer_get_extent (src_buffer);
+
+#ifdef FETCH_ROW
+  row = g_new (gfloat, src_extent->width * n_components);
+#endif
+
+  src_sampler = gegl_buffer_sampler_new (src_buffer,
+                                         format, GEGL_SAMPLER_NEAREST);
+
+  segment_queue = g_queue_new ();
+
+  push_segment (segment_queue,
+                y, /* dummy values: */ -1, 0, 0,
+                y, x - 1, x + 1);
+
+  do
+    {
+      pop_segment (segment_queue,
+                   &y, &old_y, &start, &end);
+
+      for (x = start + 1; x < end; x++)
+        {
+          gfloat val;
+
+          gegl_buffer_get (mask_buffer, GEGL_RECTANGLE (x, y, 1, 1), 1.0,
+                           mask_format, &val, GEGL_AUTO_ROWSTRIDE,
+                           GEGL_ABYSS_NONE);
+
+          if (val != 0.0)
+            {
+              /* If the current pixel is selected, then we've already visited
+               * the next pixel.  (Note that we assume that the maximal image
+               * width is sufficiently low that `x` won't overflow.)
+               */
+              x++;
+              continue;
+            }
+
+          if (! find_contiguous_segment (col,
+                                         src_buffer, src_sampler, src_extent,
+                                         mask_buffer,
+                                         format, mask_format,
+                                         n_components,
+                                         has_alpha,
+                                         select_transparent, select_criterion,
+                                         antialias, threshold, x, y,
+                                         &new_start, &new_end,
+                                         row))
+            continue;
+
+          /* We can skip directly to `new_end + 1` on the next iteration, since
+           * we've just selected all pixels in the range `[x, new_end)`, and
+           * the pixel at `new_end` is above threshold.  (Note that we assume
+           * that the maximal image width is sufficiently low that `x` won't
+           * overflow.)
+           */
+          x = new_end;
+
+          if (diagonal_neighbors)
+            {
+              if (new_start >= src_extent->x)
+                new_start--;
+
+              if (new_end < src_extent->x + src_extent->width)
+                new_end++;
+            }
+
+          if (y + 1 < src_extent->y + src_extent->height)
+            {
+              push_segment (segment_queue,
+                            y, old_y, start, end,
+                            y + 1, new_start, new_end);
+            }
+
+          if (y - 1 >= src_extent->y)
+            {
+              push_segment (segment_queue,
+                            y, old_y, start, end,
+                            y - 1, new_start, new_end);
+            }
+
+        }
+    }
+  while (! g_queue_is_empty (segment_queue));
+
+  g_queue_free (segment_queue);
+
+  g_object_unref (src_sampler);
+
+#ifdef FETCH_ROW
+  g_free (row);
+#endif
+}
+
+static void
+line_art_queue_pixel (GQueue *queue,
+                      gint    x,
+                      gint    y,
+                      gint    level)
+{
+  BorderPixel *p = g_new (BorderPixel, 1);
+
+  p->x      = x;
+  p->y      = y;
+  p->level  = level;
+
+  g_queue_push_head (queue, p);
+}
+
+} /* extern "C" */
diff --git a/app/core/gimppickable-contiguous-region.h b/app/core/gimppickable-contiguous-region.h
new file mode 100644
index 0000000..26cbe74
--- /dev/null
+++ b/app/core/gimppickable-contiguous-region.h
@@ -0,0 +1,43 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_PICKABLE_CONTIGUOUS_REGION_H__
+#define __GIMP_PICKABLE_CONTIGUOUS_REGION_H__
+
+
+GeglBuffer * gimp_pickable_contiguous_region_by_seed                (GimpPickable        *pickable,
+                                                                     gboolean             antialias,
+                                                                     gfloat               threshold,
+                                                                     gboolean             select_transparent,
+                                                                     GimpSelectCriterion  select_criterion,
+                                                                     gboolean             diagonal_neighbors,
+                                                                     gint                 x,
+                                                                     gint                 y);
+
+GeglBuffer * gimp_pickable_contiguous_region_by_color               (GimpPickable        *pickable,
+                                                                     gboolean             antialias,
+                                                                     gfloat               threshold,
+                                                                     gboolean             select_transparent,
+                                                                     GimpSelectCriterion  select_criterion,
+                                                                     const GimpRGB       *color);
+
+GeglBuffer * gimp_pickable_contiguous_region_by_line_art            (GimpPickable        *pickable,
+                                                                     GimpLineArt         *line_art,
+                                                                     gint                 x,
+                                                                     gint                 y);
+
+#endif  /*  __GIMP_PICKABLE_CONTIGUOUS_REGION_H__ */
diff --git a/app/core/gimppickable.c b/app/core/gimppickable.c
new file mode 100644
index 0000000..2949def
--- /dev/null
+++ b/app/core/gimppickable.c
@@ -0,0 +1,378 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimppickable.c
+ * Copyright (C) 2004  Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/* This file contains an interface for pixel objects that their color at
+ * a given position can be picked. Also included is a utility for
+ * sampling an average area (which uses the implemented picking
+ * functions).
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <cairo.h>
+#include <gegl.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "libgimpcolor/gimpcolor.h"
+#include "libgimpmath/gimpmath.h"
+
+#include "core-types.h"
+
+#include "gimpobject.h"
+#include "gimpimage.h"
+#include "gimppickable.h"
+
+
+/*  local function prototypes  */
+
+static void   gimp_pickable_real_get_pixel_average (GimpPickable          *pickable,
+                                                    const GeglRectangle   *rect,
+                                                    const Babl            *format,
+                                                    gpointer               pixel);
+
+
+G_DEFINE_INTERFACE (GimpPickable, gimp_pickable, GIMP_TYPE_OBJECT)
+
+
+/*  private functions  */
+
+
+static void
+gimp_pickable_default_init (GimpPickableInterface *iface)
+{
+  iface->get_pixel_average = gimp_pickable_real_get_pixel_average;
+
+  g_object_interface_install_property (iface,
+                                       g_param_spec_object ("buffer",
+                                                            NULL, NULL,
+                                                            GEGL_TYPE_BUFFER,
+                                                            GIMP_PARAM_READABLE));
+}
+
+static void
+gimp_pickable_real_get_pixel_average (GimpPickable        *pickable,
+                                      const GeglRectangle *rect,
+                                      const Babl          *format,
+                                      gpointer             pixel)
+{
+  const Babl *average_format = babl_format ("RaGaBaA double");
+  gdouble     average[4]     = {};
+  gint        n              = 0;
+  gint        x;
+  gint        y;
+  gint        c;
+
+  for (y = rect->y; y < rect->y + rect->height; y++)
+    {
+      for (x = rect->x; x < rect->x + rect->width; x++)
+        {
+          gdouble sample[4];
+
+          if (gimp_pickable_get_pixel_at (pickable,
+                                          x, y, average_format, sample))
+            {
+              for (c = 0; c < 4; c++)
+                average[c] += sample[c];
+
+              n++;
+            }
+        }
+    }
+
+  if (n > 0)
+    {
+      for (c = 0; c < 4; c++)
+        average[c] /= n;
+    }
+
+  babl_process (babl_fish (average_format, format), average, pixel, 1);
+}
+
+
+/*  public functions  */
+
+
+void
+gimp_pickable_flush (GimpPickable *pickable)
+{
+  GimpPickableInterface *pickable_iface;
+
+  g_return_if_fail (GIMP_IS_PICKABLE (pickable));
+
+  pickable_iface = GIMP_PICKABLE_GET_INTERFACE (pickable);
+
+  if (pickable_iface->flush)
+    pickable_iface->flush (pickable);
+}
+
+GimpImage *
+gimp_pickable_get_image (GimpPickable *pickable)
+{
+  GimpPickableInterface *pickable_iface;
+
+  g_return_val_if_fail (GIMP_IS_PICKABLE (pickable), NULL);
+
+  pickable_iface = GIMP_PICKABLE_GET_INTERFACE (pickable);
+
+  if (pickable_iface->get_image)
+    return pickable_iface->get_image (pickable);
+
+  return NULL;
+}
+
+const Babl *
+gimp_pickable_get_format (GimpPickable *pickable)
+{
+  GimpPickableInterface *pickable_iface;
+
+  g_return_val_if_fail (GIMP_IS_PICKABLE (pickable), NULL);
+
+  pickable_iface = GIMP_PICKABLE_GET_INTERFACE (pickable);
+
+  if (pickable_iface->get_format)
+    return pickable_iface->get_format (pickable);
+
+  return NULL;
+}
+
+const Babl *
+gimp_pickable_get_format_with_alpha (GimpPickable *pickable)
+{
+  GimpPickableInterface *pickable_iface;
+
+  g_return_val_if_fail (GIMP_IS_PICKABLE (pickable), NULL);
+
+  pickable_iface = GIMP_PICKABLE_GET_INTERFACE (pickable);
+
+  if (pickable_iface->get_format_with_alpha)
+    return pickable_iface->get_format_with_alpha (pickable);
+
+  return NULL;
+}
+
+GeglBuffer *
+gimp_pickable_get_buffer (GimpPickable *pickable)
+{
+  GimpPickableInterface *pickable_iface;
+
+  g_return_val_if_fail (GIMP_IS_PICKABLE (pickable), NULL);
+
+  pickable_iface = GIMP_PICKABLE_GET_INTERFACE (pickable);
+
+  if (pickable_iface->get_buffer)
+    return pickable_iface->get_buffer (pickable);
+
+  return NULL;
+}
+
+gboolean
+gimp_pickable_get_pixel_at (GimpPickable *pickable,
+                            gint          x,
+                            gint          y,
+                            const Babl   *format,
+                            gpointer      pixel)
+{
+  GimpPickableInterface *pickable_iface;
+
+  g_return_val_if_fail (GIMP_IS_PICKABLE (pickable), FALSE);
+  g_return_val_if_fail (pixel != NULL, FALSE);
+
+  if (! format)
+    format = gimp_pickable_get_format (pickable);
+
+  pickable_iface = GIMP_PICKABLE_GET_INTERFACE (pickable);
+
+  if (pickable_iface->get_pixel_at)
+    return pickable_iface->get_pixel_at (pickable, x, y, format, pixel);
+
+  return FALSE;
+}
+
+void
+gimp_pickable_get_pixel_average (GimpPickable        *pickable,
+                                 const GeglRectangle *rect,
+                                 const Babl          *format,
+                                 gpointer             pixel)
+{
+  GimpPickableInterface *pickable_iface;
+
+  g_return_if_fail (GIMP_IS_PICKABLE (pickable));
+  g_return_if_fail (rect != NULL);
+  g_return_if_fail (pixel != NULL);
+
+  if (! format)
+    format = gimp_pickable_get_format (pickable);
+
+  pickable_iface = GIMP_PICKABLE_GET_INTERFACE (pickable);
+
+  if (pickable_iface->get_pixel_average)
+    pickable_iface->get_pixel_average (pickable, rect, format, pixel);
+  else
+    memset (pixel, 0, babl_format_get_bytes_per_pixel (format));
+}
+
+gboolean
+gimp_pickable_get_color_at (GimpPickable *pickable,
+                            gint          x,
+                            gint          y,
+                            GimpRGB      *color)
+{
+  gdouble pixel[4];
+
+  g_return_val_if_fail (GIMP_IS_PICKABLE (pickable), FALSE);
+  g_return_val_if_fail (color != NULL, FALSE);
+
+  if (! gimp_pickable_get_pixel_at (pickable, x, y, NULL, pixel))
+    return FALSE;
+
+  gimp_pickable_pixel_to_srgb (pickable, NULL, pixel, color);
+
+  return TRUE;
+}
+
+gdouble
+gimp_pickable_get_opacity_at (GimpPickable *pickable,
+                              gint          x,
+                              gint          y)
+{
+  GimpPickableInterface *pickable_iface;
+
+  g_return_val_if_fail (GIMP_IS_PICKABLE (pickable), GIMP_OPACITY_TRANSPARENT);
+
+  pickable_iface = GIMP_PICKABLE_GET_INTERFACE (pickable);
+
+  if (pickable_iface->get_opacity_at)
+    return pickable_iface->get_opacity_at (pickable, x, y);
+
+  return GIMP_OPACITY_TRANSPARENT;
+}
+
+void
+gimp_pickable_pixel_to_srgb (GimpPickable *pickable,
+                             const Babl   *format,
+                             gpointer      pixel,
+                             GimpRGB      *color)
+{
+  GimpPickableInterface *pickable_iface;
+
+  g_return_if_fail (GIMP_IS_PICKABLE (pickable));
+  g_return_if_fail (pixel != NULL);
+  g_return_if_fail (color != NULL);
+
+  if (! format)
+    format = gimp_pickable_get_format (pickable);
+
+  pickable_iface = GIMP_PICKABLE_GET_INTERFACE (pickable);
+
+  if (pickable_iface->pixel_to_srgb)
+    {
+      pickable_iface->pixel_to_srgb (pickable, format, pixel, color);
+    }
+  else
+    {
+      gimp_rgba_set_pixel (color, format, pixel);
+    }
+}
+
+void
+gimp_pickable_srgb_to_pixel (GimpPickable  *pickable,
+                             const GimpRGB *color,
+                             const Babl    *format,
+                             gpointer       pixel)
+{
+  GimpPickableInterface *pickable_iface;
+
+  g_return_if_fail (GIMP_IS_PICKABLE (pickable));
+  g_return_if_fail (color != NULL);
+  g_return_if_fail (pixel != NULL);
+
+  if (! format)
+    format = gimp_pickable_get_format (pickable);
+
+  pickable_iface = GIMP_PICKABLE_GET_INTERFACE (pickable);
+
+  if (pickable_iface->srgb_to_pixel)
+    {
+      pickable_iface->srgb_to_pixel (pickable, color, format, pixel);
+    }
+  else
+    {
+      gimp_rgba_get_pixel (color, format, pixel);
+    }
+}
+
+void
+gimp_pickable_srgb_to_image_color (GimpPickable  *pickable,
+                                   const GimpRGB *color,
+                                   GimpRGB       *image_color)
+{
+  g_return_if_fail (GIMP_IS_PICKABLE (pickable));
+  g_return_if_fail (color != NULL);
+  g_return_if_fail (image_color != NULL);
+
+  gimp_pickable_srgb_to_pixel (pickable,
+                               color,
+                               babl_format ("R'G'B'A double"),
+                               image_color);
+}
+
+gboolean
+gimp_pickable_pick_color (GimpPickable *pickable,
+                          gint          x,
+                          gint          y,
+                          gboolean      sample_average,
+                          gdouble       average_radius,
+                          gpointer      pixel,
+                          GimpRGB      *color)
+{
+  const Babl *format;
+  gdouble     sample[4];
+
+  g_return_val_if_fail (GIMP_IS_PICKABLE (pickable), FALSE);
+  g_return_val_if_fail (color != NULL, FALSE);
+
+  format = gimp_pickable_get_format (pickable);
+
+  if (! gimp_pickable_get_pixel_at (pickable, x, y, format, sample))
+    return FALSE;
+
+  if (pixel)
+    memcpy (pixel, sample, babl_format_get_bytes_per_pixel (format));
+
+  if (sample_average)
+    {
+      gint radius = floor (average_radius);
+
+      format = babl_format ("RaGaBaA double");
+
+      gimp_pickable_get_pixel_average (pickable,
+                                       GEGL_RECTANGLE (x - radius,
+                                                       y - radius,
+                                                       2 * radius + 1,
+                                                       2 * radius + 1),
+                                       format, sample);
+    }
+
+  gimp_pickable_pixel_to_srgb (pickable, format, sample, color);
+
+  return TRUE;
+}
diff --git a/app/core/gimppickable.h b/app/core/gimppickable.h
new file mode 100644
index 0000000..c8c77c9
--- /dev/null
+++ b/app/core/gimppickable.h
@@ -0,0 +1,110 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1997 Spencer Kimball and Peter Mattis
+ *
+ * gimppickable.h
+ * Copyright (C) 2004  Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_PICKABLE_H__
+#define __GIMP_PICKABLE_H__
+
+
+#define GIMP_TYPE_PICKABLE               (gimp_pickable_get_type ())
+#define GIMP_IS_PICKABLE(obj)            (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_PICKABLE))
+#define GIMP_PICKABLE(obj)               (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_PICKABLE, GimpPickable))
+#define GIMP_PICKABLE_GET_INTERFACE(obj) (G_TYPE_INSTANCE_GET_INTERFACE ((obj), GIMP_TYPE_PICKABLE, GimpPickableInterface))
+
+
+typedef struct _GimpPickableInterface GimpPickableInterface;
+
+struct _GimpPickableInterface
+{
+  GTypeInterface base_iface;
+
+  /*  virtual functions  */
+  void            (* flush)                 (GimpPickable        *pickable);
+  GimpImage     * (* get_image)             (GimpPickable        *pickable);
+  const Babl    * (* get_format)            (GimpPickable        *pickable);
+  const Babl    * (* get_format_with_alpha) (GimpPickable        *pickable);
+  GeglBuffer    * (* get_buffer)            (GimpPickable        *pickable);
+  gboolean        (* get_pixel_at)          (GimpPickable        *pickable,
+                                             gint                 x,
+                                             gint                 y,
+                                             const Babl          *format,
+                                             gpointer             pixel);
+  gdouble         (* get_opacity_at)        (GimpPickable        *pickable,
+                                             gint                 x,
+                                             gint                 y);
+  void            (* get_pixel_average)     (GimpPickable        *pickable,
+                                             const GeglRectangle *rect,
+                                             const Babl          *format,
+                                             gpointer             pixel);
+  void            (* pixel_to_srgb)         (GimpPickable        *pickable,
+                                             const Babl          *format,
+                                             gpointer             pixel,
+                                             GimpRGB             *color);
+  void            (* srgb_to_pixel)         (GimpPickable        *pickable,
+                                             const GimpRGB       *color,
+                                             const Babl          *format,
+                                             gpointer             pixel);
+};
+
+
+GType           gimp_pickable_get_type              (void) G_GNUC_CONST;
+
+void            gimp_pickable_flush                 (GimpPickable        *pickable);
+GimpImage     * gimp_pickable_get_image             (GimpPickable        *pickable);
+const Babl    * gimp_pickable_get_format            (GimpPickable        *pickable);
+const Babl    * gimp_pickable_get_format_with_alpha (GimpPickable        *pickable);
+GeglBuffer    * gimp_pickable_get_buffer            (GimpPickable        *pickable);
+gboolean        gimp_pickable_get_pixel_at          (GimpPickable        *pickable,
+                                                     gint                 x,
+                                                     gint                 y,
+                                                     const Babl          *format,
+                                                     gpointer             pixel);
+gboolean        gimp_pickable_get_color_at          (GimpPickable        *pickable,
+                                                     gint                 x,
+                                                     gint                 y,
+                                                     GimpRGB             *color);
+gdouble         gimp_pickable_get_opacity_at        (GimpPickable        *pickable,
+                                                     gint                 x,
+                                                     gint                 y);
+void            gimp_pickable_get_pixel_average     (GimpPickable        *pickable,
+                                                     const GeglRectangle *rect,
+                                                     const Babl          *format,
+                                                     gpointer             pixel);
+void            gimp_pickable_pixel_to_srgb         (GimpPickable        *pickable,
+                                                     const Babl          *format,
+                                                     gpointer             pixel,
+                                                     GimpRGB             *color);
+void            gimp_pickable_srgb_to_pixel         (GimpPickable        *pickable,
+                                                     const GimpRGB       *color,
+                                                     const Babl          *format,
+                                                     gpointer             pixel);
+void            gimp_pickable_srgb_to_image_color   (GimpPickable        *pickable,
+                                                     const GimpRGB       *color,
+                                                     GimpRGB             *image_color);
+
+gboolean        gimp_pickable_pick_color            (GimpPickable        *pickable,
+                                                     gint                 x,
+                                                     gint                 y,
+                                                     gboolean             sample_average,
+                                                     gdouble              average_radius,
+                                                     gpointer             pixel,
+                                                     GimpRGB             *color);
+
+
+#endif  /* __GIMP_PICKABLE_H__ */
diff --git a/app/core/gimpprogress.c b/app/core/gimpprogress.c
new file mode 100644
index 0000000..6b8bf46
--- /dev/null
+++ b/app/core/gimpprogress.c
@@ -0,0 +1,266 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpprogress.c
+ * Copyright (C) 2004  Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <gio/gio.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gimp.h"
+#include "gimpmarshal.h"
+#include "gimpprogress.h"
+
+#include "gimp-intl.h"
+
+
+enum
+{
+  CANCEL,
+  LAST_SIGNAL
+};
+
+
+G_DEFINE_INTERFACE (GimpProgress, gimp_progress, G_TYPE_OBJECT)
+
+
+static guint progress_signals[LAST_SIGNAL] = { 0 };
+
+
+/*  private functions  */
+
+
+static void
+gimp_progress_default_init (GimpProgressInterface *progress_iface)
+{
+  progress_signals[CANCEL] =
+    g_signal_new ("cancel",
+                  G_TYPE_FROM_INTERFACE (progress_iface),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpProgressInterface, cancel),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+}
+
+
+/*  public functions  */
+
+
+GimpProgress *
+gimp_progress_start (GimpProgress *progress,
+                     gboolean      cancellable,
+                     const gchar  *format,
+                     ...)
+{
+  GimpProgressInterface *progress_iface;
+
+  g_return_val_if_fail (GIMP_IS_PROGRESS (progress), NULL);
+  g_return_val_if_fail (format != NULL, NULL);
+
+  progress_iface = GIMP_PROGRESS_GET_INTERFACE (progress);
+
+  if (progress_iface->start)
+    {
+      GimpProgress *ret;
+      va_list       args;
+      gchar        *text;
+
+      va_start (args, format);
+      text = g_strdup_vprintf (format, args);
+      va_end (args);
+
+      ret = progress_iface->start (progress, cancellable, text);
+
+      g_free (text);
+
+      return ret;
+    }
+
+  return NULL;
+}
+
+void
+gimp_progress_end (GimpProgress *progress)
+{
+  GimpProgressInterface *progress_iface;
+
+  g_return_if_fail (GIMP_IS_PROGRESS (progress));
+
+  progress_iface = GIMP_PROGRESS_GET_INTERFACE (progress);
+
+  if (progress_iface->end)
+    progress_iface->end (progress);
+}
+
+gboolean
+gimp_progress_is_active (GimpProgress *progress)
+{
+  GimpProgressInterface *progress_iface;
+
+  g_return_val_if_fail (GIMP_IS_PROGRESS (progress), FALSE);
+
+  progress_iface = GIMP_PROGRESS_GET_INTERFACE (progress);
+
+  if (progress_iface->is_active)
+    return progress_iface->is_active (progress);
+
+  return FALSE;
+}
+
+void
+gimp_progress_set_text (GimpProgress *progress,
+                        const gchar  *format,
+                        ...)
+{
+  va_list  args;
+  gchar   *message;
+
+  g_return_if_fail (GIMP_IS_PROGRESS (progress));
+  g_return_if_fail (format != NULL);
+
+  va_start (args, format);
+  message = g_strdup_vprintf (format, args);
+  va_end (args);
+
+  gimp_progress_set_text_literal (progress, message);
+
+  g_free (message);
+}
+
+void
+gimp_progress_set_text_literal (GimpProgress *progress,
+                                const gchar  *message)
+{
+  GimpProgressInterface *progress_iface;
+
+  g_return_if_fail (GIMP_IS_PROGRESS (progress));
+  g_return_if_fail (message != NULL);
+
+  progress_iface = GIMP_PROGRESS_GET_INTERFACE (progress);
+
+  if (progress_iface->set_text)
+    progress_iface->set_text (progress, message);
+}
+
+void
+gimp_progress_set_value (GimpProgress *progress,
+                         gdouble       percentage)
+{
+  GimpProgressInterface *progress_iface;
+
+  g_return_if_fail (GIMP_IS_PROGRESS (progress));
+
+  percentage = CLAMP (percentage, 0.0, 1.0);
+
+  progress_iface = GIMP_PROGRESS_GET_INTERFACE (progress);
+
+  if (progress_iface->set_value)
+    progress_iface->set_value (progress, percentage);
+}
+
+gdouble
+gimp_progress_get_value (GimpProgress *progress)
+{
+  GimpProgressInterface *progress_iface;
+
+  g_return_val_if_fail (GIMP_IS_PROGRESS (progress), 0.0);
+
+  progress_iface = GIMP_PROGRESS_GET_INTERFACE (progress);
+
+  if (progress_iface->get_value)
+    return progress_iface->get_value (progress);
+
+  return 0.0;
+}
+
+void
+gimp_progress_pulse (GimpProgress *progress)
+{
+  GimpProgressInterface *progress_iface;
+
+  g_return_if_fail (GIMP_IS_PROGRESS (progress));
+
+  progress_iface = GIMP_PROGRESS_GET_INTERFACE (progress);
+
+  if (progress_iface->pulse)
+    progress_iface->pulse (progress);
+}
+
+guint32
+gimp_progress_get_window_id (GimpProgress *progress)
+{
+  GimpProgressInterface *progress_iface;
+
+  g_return_val_if_fail (GIMP_IS_PROGRESS (progress), 0);
+
+  progress_iface = GIMP_PROGRESS_GET_INTERFACE (progress);
+
+  if (progress_iface->get_window_id)
+    return progress_iface->get_window_id (progress);
+
+  return 0;
+}
+
+gboolean
+gimp_progress_message (GimpProgress        *progress,
+                       Gimp                *gimp,
+                       GimpMessageSeverity  severity,
+                       const gchar         *domain,
+                       const gchar         *message)
+{
+  GimpProgressInterface *progress_iface;
+
+  g_return_val_if_fail (GIMP_IS_PROGRESS (progress), FALSE);
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), FALSE);
+  g_return_val_if_fail (domain != NULL, FALSE);
+  g_return_val_if_fail (message != NULL, FALSE);
+
+  progress_iface = GIMP_PROGRESS_GET_INTERFACE (progress);
+
+  if (progress_iface->message)
+    return progress_iface->message (progress, gimp, severity, domain, message);
+
+  return FALSE;
+}
+
+void
+gimp_progress_cancel (GimpProgress *progress)
+{
+  g_return_if_fail (GIMP_IS_PROGRESS (progress));
+
+  g_signal_emit (progress, progress_signals[CANCEL], 0);
+}
+
+void
+gimp_progress_update_and_flush (gint     min,
+                                gint     max,
+                                gint     current,
+                                gpointer data)
+{
+  gimp_progress_set_value (GIMP_PROGRESS (data),
+                           (gdouble) (current - min) / (gdouble) (max - min));
+
+  while (g_main_context_pending (NULL))
+    g_main_context_iteration (NULL, TRUE);
+}
diff --git a/app/core/gimpprogress.h b/app/core/gimpprogress.h
new file mode 100644
index 0000000..488f050
--- /dev/null
+++ b/app/core/gimpprogress.h
@@ -0,0 +1,99 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpprogress.h
+ * Copyright (C) 2004  Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_PROGRESS_H__
+#define __GIMP_PROGRESS_H__
+
+
+#define GIMP_TYPE_PROGRESS               (gimp_progress_get_type ())
+#define GIMP_IS_PROGRESS(obj)            (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_PROGRESS))
+#define GIMP_PROGRESS(obj)               (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_PROGRESS, GimpProgress))
+#define GIMP_PROGRESS_GET_INTERFACE(obj) (G_TYPE_INSTANCE_GET_INTERFACE ((obj), GIMP_TYPE_PROGRESS, GimpProgressInterface))
+
+
+typedef struct _GimpProgressInterface GimpProgressInterface;
+
+struct _GimpProgressInterface
+{
+  GTypeInterface base_iface;
+
+  /*  virtual functions  */
+  GimpProgress * (* start)         (GimpProgress        *progress,
+                                    gboolean             cancellable,
+                                    const gchar         *message);
+  void           (* end)           (GimpProgress        *progress);
+  gboolean       (* is_active)     (GimpProgress        *progress);
+
+  void           (* set_text)      (GimpProgress        *progress,
+                                    const gchar         *message);
+  void           (* set_value)     (GimpProgress        *progress,
+                                    gdouble              percentage);
+  gdouble        (* get_value)     (GimpProgress        *progress);
+  void           (* pulse)         (GimpProgress        *progress);
+
+  guint32        (* get_window_id) (GimpProgress        *progress);
+
+  gboolean       (* message)       (GimpProgress        *progress,
+                                    Gimp                *gimp,
+                                    GimpMessageSeverity  severity,
+                                    const gchar         *domain,
+                                    const gchar         *message);
+
+  /*  signals  */
+  void           (* cancel)        (GimpProgress        *progress);
+};
+
+
+GType          gimp_progress_get_type         (void) G_GNUC_CONST;
+
+GimpProgress * gimp_progress_start            (GimpProgress        *progress,
+                                               gboolean             cancellable,
+                                               const gchar         *format,
+                                               ...) G_GNUC_PRINTF (3, 4);
+void           gimp_progress_end              (GimpProgress        *progress);
+gboolean       gimp_progress_is_active        (GimpProgress        *progress);
+
+void           gimp_progress_set_text         (GimpProgress        *progress,
+                                               const gchar         *format,
+                                               ...) G_GNUC_PRINTF (2, 3);
+void           gimp_progress_set_text_literal (GimpProgress        *progress,
+                                               const gchar         *message);
+void           gimp_progress_set_value        (GimpProgress        *progress,
+                                               gdouble              percentage);
+gdouble        gimp_progress_get_value        (GimpProgress        *progress);
+void           gimp_progress_pulse            (GimpProgress        *progress);
+
+guint32        gimp_progress_get_window_id    (GimpProgress        *progress);
+
+gboolean       gimp_progress_message          (GimpProgress        *progress,
+                                               Gimp                *gimp,
+                                               GimpMessageSeverity  severity,
+                                               const gchar         *domain,
+                                               const gchar         *message);
+
+void           gimp_progress_cancel           (GimpProgress        *progress);
+
+void           gimp_progress_update_and_flush (gint                 min,
+                                               gint                 max,
+                                               gint                 current,
+                                               gpointer             data);
+
+
+#endif /* __GIMP_PROGRESS_H__ */
diff --git a/app/core/gimpprojectable.c b/app/core/gimpprojectable.c
new file mode 100644
index 0000000..8814c98
--- /dev/null
+++ b/app/core/gimpprojectable.c
@@ -0,0 +1,262 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpprojectable.c
+ * Copyright (C) 2008  Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gimpmarshal.h"
+#include "gimpprojectable.h"
+#include "gimpviewable.h"
+
+
+enum
+{
+  INVALIDATE,
+  FLUSH,
+  STRUCTURE_CHANGED,
+  BOUNDS_CHANGED,
+  LAST_SIGNAL
+};
+
+
+G_DEFINE_INTERFACE (GimpProjectable, gimp_projectable, GIMP_TYPE_VIEWABLE)
+
+
+static guint projectable_signals[LAST_SIGNAL] = { 0 };
+
+
+/*  private functions  */
+
+
+static void
+gimp_projectable_default_init (GimpProjectableInterface *iface)
+{
+  projectable_signals[INVALIDATE] =
+    g_signal_new ("invalidate",
+                  G_TYPE_FROM_CLASS (iface),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpProjectableInterface, invalidate),
+                  NULL, NULL,
+                  gimp_marshal_VOID__INT_INT_INT_INT,
+                  G_TYPE_NONE, 4,
+                  G_TYPE_INT,
+                  G_TYPE_INT,
+                  G_TYPE_INT,
+                  G_TYPE_INT);
+
+  projectable_signals[FLUSH] =
+    g_signal_new ("flush",
+                  G_TYPE_FROM_CLASS (iface),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpProjectableInterface, flush),
+                  NULL, NULL,
+                  gimp_marshal_VOID__BOOLEAN,
+                  G_TYPE_NONE, 1,
+                  G_TYPE_BOOLEAN);
+
+  projectable_signals[STRUCTURE_CHANGED] =
+    g_signal_new ("structure-changed",
+                  G_TYPE_FROM_CLASS (iface),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpProjectableInterface, structure_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  projectable_signals[BOUNDS_CHANGED] =
+    g_signal_new ("bounds-changed",
+                  G_TYPE_FROM_CLASS (iface),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpProjectableInterface, bounds_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__INT_INT,
+                  G_TYPE_NONE, 2,
+                  G_TYPE_INT,
+                  G_TYPE_INT);
+}
+
+
+/*  public functions  */
+
+void
+gimp_projectable_invalidate (GimpProjectable *projectable,
+                             gint             x,
+                             gint             y,
+                             gint             width,
+                             gint             height)
+{
+  g_return_if_fail (GIMP_IS_PROJECTABLE (projectable));
+
+  g_signal_emit (projectable, projectable_signals[INVALIDATE], 0,
+                 x, y, width, height);
+}
+
+void
+gimp_projectable_flush (GimpProjectable *projectable,
+                        gboolean         preview_invalidated)
+{
+  g_return_if_fail (GIMP_IS_PROJECTABLE (projectable));
+
+  g_signal_emit (projectable, projectable_signals[FLUSH], 0,
+                 preview_invalidated);
+}
+
+void
+gimp_projectable_structure_changed (GimpProjectable *projectable)
+{
+  g_return_if_fail (GIMP_IS_PROJECTABLE (projectable));
+
+  g_signal_emit (projectable, projectable_signals[STRUCTURE_CHANGED], 0);
+}
+
+void
+gimp_projectable_bounds_changed (GimpProjectable *projectable,
+                                 gint             old_x,
+                                 gint             old_y)
+{
+  g_return_if_fail (GIMP_IS_PROJECTABLE (projectable));
+
+  g_signal_emit (projectable, projectable_signals[BOUNDS_CHANGED], 0,
+                 old_x, old_y);
+}
+
+GimpImage *
+gimp_projectable_get_image (GimpProjectable *projectable)
+{
+  GimpProjectableInterface *iface;
+
+  g_return_val_if_fail (GIMP_IS_PROJECTABLE (projectable), NULL);
+
+  iface = GIMP_PROJECTABLE_GET_INTERFACE (projectable);
+
+  if (iface->get_image)
+    return iface->get_image (projectable);
+
+  return NULL;
+}
+
+const Babl *
+gimp_projectable_get_format (GimpProjectable *projectable)
+{
+  GimpProjectableInterface *iface;
+
+  g_return_val_if_fail (GIMP_IS_PROJECTABLE (projectable), NULL);
+
+  iface = GIMP_PROJECTABLE_GET_INTERFACE (projectable);
+
+  if (iface->get_format)
+    return iface->get_format (projectable);
+
+  return 0;
+}
+
+void
+gimp_projectable_get_offset (GimpProjectable *projectable,
+                             gint            *x,
+                             gint            *y)
+{
+  GimpProjectableInterface *iface;
+
+  g_return_if_fail (GIMP_IS_PROJECTABLE (projectable));
+  g_return_if_fail (x != NULL);
+  g_return_if_fail (y != NULL);
+
+  iface = GIMP_PROJECTABLE_GET_INTERFACE (projectable);
+
+  *x = 0;
+  *y = 0;
+
+  if (iface->get_offset)
+    iface->get_offset (projectable, x, y);
+}
+
+GeglRectangle
+gimp_projectable_get_bounding_box (GimpProjectable *projectable)
+{
+  GimpProjectableInterface *iface;
+  GeglRectangle             result = {};
+
+  g_return_val_if_fail (GIMP_IS_PROJECTABLE (projectable), result);
+
+  iface = GIMP_PROJECTABLE_GET_INTERFACE (projectable);
+
+  if (iface->get_bounding_box)
+    result = iface->get_bounding_box (projectable);
+
+  return result;
+}
+
+GeglNode *
+gimp_projectable_get_graph (GimpProjectable *projectable)
+{
+  GimpProjectableInterface *iface;
+
+  g_return_val_if_fail (GIMP_IS_PROJECTABLE (projectable), NULL);
+
+  iface = GIMP_PROJECTABLE_GET_INTERFACE (projectable);
+
+  if (iface->get_graph)
+    return iface->get_graph (projectable);
+
+  return NULL;
+}
+
+void
+gimp_projectable_begin_render (GimpProjectable *projectable)
+{
+  GimpProjectableInterface *iface;
+
+  g_return_if_fail (GIMP_IS_PROJECTABLE (projectable));
+
+  iface = GIMP_PROJECTABLE_GET_INTERFACE (projectable);
+
+  if (iface->begin_render)
+    iface->begin_render (projectable);
+}
+
+void
+gimp_projectable_end_render (GimpProjectable *projectable)
+{
+  GimpProjectableInterface *iface;
+
+  g_return_if_fail (GIMP_IS_PROJECTABLE (projectable));
+
+  iface = GIMP_PROJECTABLE_GET_INTERFACE (projectable);
+
+  if (iface->end_render)
+    iface->end_render (projectable);
+}
+
+void
+gimp_projectable_invalidate_preview (GimpProjectable *projectable)
+{
+  GimpProjectableInterface *iface;
+
+  g_return_if_fail (GIMP_IS_PROJECTABLE (projectable));
+
+  iface = GIMP_PROJECTABLE_GET_INTERFACE (projectable);
+
+  if (iface->invalidate_preview)
+    iface->invalidate_preview (projectable);
+}
diff --git a/app/core/gimpprojectable.h b/app/core/gimpprojectable.h
new file mode 100644
index 0000000..955f3a4
--- /dev/null
+++ b/app/core/gimpprojectable.h
@@ -0,0 +1,90 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1997 Spencer Kimball and Peter Mattis
+ *
+ * gimpprojectable.h
+ * Copyright (C) 2008  Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_PROJECTABLE_H__
+#define __GIMP_PROJECTABLE_H__
+
+
+#define GIMP_TYPE_PROJECTABLE               (gimp_projectable_get_type ())
+#define GIMP_IS_PROJECTABLE(obj)            (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_PROJECTABLE))
+#define GIMP_PROJECTABLE(obj)               (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_PROJECTABLE, GimpProjectable))
+#define GIMP_PROJECTABLE_GET_INTERFACE(obj) (G_TYPE_INSTANCE_GET_INTERFACE ((obj), GIMP_TYPE_PROJECTABLE, GimpProjectableInterface))
+
+
+typedef struct _GimpProjectableInterface GimpProjectableInterface;
+
+struct _GimpProjectableInterface
+{
+  GTypeInterface base_iface;
+
+  /*  signals  */
+  void         (* invalidate)         (GimpProjectable *projectable,
+                                       gint             x,
+                                       gint             y,
+                                       gint             width,
+                                       gint             height);
+  void         (* flush)              (GimpProjectable *projectable,
+                                       gboolean         invalidate_preview);
+  void         (* structure_changed)  (GimpProjectable *projectable);
+  void         (* bounds_changed)     (GimpProjectable *projectable,
+                                       gint             old_x,
+                                       gint             old_y);
+
+  /*  virtual functions  */
+  GimpImage  * (* get_image)          (GimpProjectable *projectable);
+  const Babl * (* get_format)         (GimpProjectable *projectable);
+  void         (* get_offset)         (GimpProjectable *projectable,
+                                       gint            *x,
+                                       gint            *y);
+  GeglRectangle (* get_bounding_box)  (GimpProjectable *projectable);
+  GeglNode   * (* get_graph)          (GimpProjectable *projectable);
+  void         (* begin_render)       (GimpProjectable *projectable);
+  void         (* end_render)         (GimpProjectable *projectable);
+  void         (* invalidate_preview) (GimpProjectable *projectable);
+};
+
+
+GType        gimp_projectable_get_type           (void) G_GNUC_CONST;
+
+void         gimp_projectable_invalidate         (GimpProjectable *projectable,
+                                                  gint             x,
+                                                  gint             y,
+                                                  gint             width,
+                                                  gint             height);
+void         gimp_projectable_flush              (GimpProjectable *projectable,
+                                                  gboolean         preview_invalidated);
+void         gimp_projectable_structure_changed  (GimpProjectable *projectable);
+void         gimp_projectable_bounds_changed     (GimpProjectable *projectable,
+                                                  gint             old_x,
+                                                  gint             old_y);
+
+GimpImage  * gimp_projectable_get_image          (GimpProjectable *projectable);
+const Babl * gimp_projectable_get_format         (GimpProjectable *projectable);
+void         gimp_projectable_get_offset         (GimpProjectable *projectable,
+                                                  gint            *x,
+                                                  gint            *y);
+GeglRectangle gimp_projectable_get_bounding_box  (GimpProjectable *projectable);
+GeglNode   * gimp_projectable_get_graph          (GimpProjectable *projectable);
+void         gimp_projectable_begin_render       (GimpProjectable *projectable);
+void         gimp_projectable_end_render         (GimpProjectable *projectable);
+void         gimp_projectable_invalidate_preview (GimpProjectable *projectable);
+
+
+#endif  /* __GIMP_PROJECTABLE_H__ */
diff --git a/app/core/gimpprojection.c b/app/core/gimpprojection.c
new file mode 100644
index 0000000..c249b55
--- /dev/null
+++ b/app/core/gimpprojection.c
@@ -0,0 +1,1132 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+#include <cairo.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpmath/gimpmath.h"
+
+#include "core-types.h"
+
+#include "gegl/gimp-babl.h"
+#include "gegl/gimp-gegl-loops.h"
+#include "gegl/gimp-gegl-utils.h"
+
+#include "gimp.h"
+#include "gimp-memsize.h"
+#include "gimpchunkiterator.h"
+#include "gimpimage.h"
+#include "gimpmarshal.h"
+#include "gimppickable.h"
+#include "gimpprojectable.h"
+#include "gimpprojection.h"
+#include "gimptilehandlerprojectable.h"
+
+#include "gimp-log.h"
+#include "gimp-priorities.h"
+
+
+/*  chunk size for area updates  */
+#define GIMP_PROJECTION_UPDATE_CHUNK_WIDTH  32
+#define GIMP_PROJECTION_UPDATE_CHUNK_HEIGHT 32
+
+
+enum
+{
+  UPDATE,
+  LAST_SIGNAL
+};
+
+enum
+{
+  PROP_0,
+  PROP_BUFFER
+};
+
+
+struct _GimpProjectionPrivate
+{
+  GimpProjectable           *projectable;
+
+  GeglBuffer                *buffer;
+  GimpTileHandlerValidate   *validate_handler;
+
+  gint                       priority;
+
+  cairo_region_t            *update_region;
+  GeglRectangle              priority_rect;
+  GimpChunkIterator         *iter;
+  guint                      idle_id;
+
+  gboolean                   invalidate_preview;
+};
+
+
+/*  local function prototypes  */
+
+static void   gimp_projection_pickable_iface_init (GimpPickableInterface  *iface);
+
+static void        gimp_projection_finalize              (GObject         *object);
+static void        gimp_projection_set_property          (GObject         *object,
+                                                          guint            property_id,
+                                                          const GValue    *value,
+                                                          GParamSpec      *pspec);
+static void        gimp_projection_get_property          (GObject         *object,
+                                                          guint            property_id,
+                                                          GValue          *value,
+                                                          GParamSpec      *pspec);
+
+static gint64      gimp_projection_get_memsize           (GimpObject      *object,
+                                                          gint64          *gui_size);
+
+static void        gimp_projection_pickable_flush        (GimpPickable    *pickable);
+static GimpImage * gimp_projection_get_image             (GimpPickable    *pickable);
+static const Babl * gimp_projection_get_format           (GimpPickable    *pickable);
+static GeglBuffer * gimp_projection_get_buffer           (GimpPickable    *pickable);
+static gboolean    gimp_projection_get_pixel_at          (GimpPickable    *pickable,
+                                                          gint             x,
+                                                          gint             y,
+                                                          const Babl      *format,
+                                                          gpointer         pixel);
+static gdouble     gimp_projection_get_opacity_at        (GimpPickable    *pickable,
+                                                          gint             x,
+                                                          gint             y);
+static void        gimp_projection_get_pixel_average     (GimpPickable    *pickable,
+                                                          const GeglRectangle *rect,
+                                                          const Babl      *format,
+                                                          gpointer         pixel);
+static void        gimp_projection_pixel_to_srgb         (GimpPickable    *pickable,
+                                                          const Babl      *format,
+                                                          gpointer         pixel,
+                                                          GimpRGB         *color);
+static void        gimp_projection_srgb_to_pixel         (GimpPickable    *pickable,
+                                                          const GimpRGB   *color,
+                                                          const Babl      *format,
+                                                          gpointer         pixel);
+
+static void        gimp_projection_allocate_buffer       (GimpProjection  *proj);
+static void        gimp_projection_free_buffer           (GimpProjection  *proj);
+static void        gimp_projection_add_update_area       (GimpProjection  *proj,
+                                                          gint             x,
+                                                          gint             y,
+                                                          gint             w,
+                                                          gint             h);
+static void        gimp_projection_flush_whenever        (GimpProjection  *proj,
+                                                          gboolean         now,
+                                                          gboolean         direct);
+static void        gimp_projection_update_priority_rect  (GimpProjection  *proj);
+static void        gimp_projection_chunk_render_start    (GimpProjection  *proj);
+static void        gimp_projection_chunk_render_stop     (GimpProjection  *proj,
+                                                          gboolean         merge);
+static gboolean    gimp_projection_chunk_render_callback (GimpProjection  *proj);
+static gboolean    gimp_projection_chunk_render_iteration(GimpProjection  *proj);
+static void        gimp_projection_paint_area            (GimpProjection  *proj,
+                                                          gboolean         now,
+                                                          gint             x,
+                                                          gint             y,
+                                                          gint             w,
+                                                          gint             h);
+
+static void        gimp_projection_projectable_invalidate(GimpProjectable *projectable,
+                                                          gint             x,
+                                                          gint             y,
+                                                          gint             w,
+                                                          gint             h,
+                                                          GimpProjection  *proj);
+static void        gimp_projection_projectable_flush     (GimpProjectable *projectable,
+                                                          gboolean         invalidate_preview,
+                                                          GimpProjection  *proj);
+static void
+           gimp_projection_projectable_structure_changed (GimpProjectable *projectable,
+                                                          GimpProjection  *proj);
+static void   gimp_projection_projectable_bounds_changed (GimpProjectable *projectable,
+                                                          gint             old_x,
+                                                          gint             old_y,
+                                                          GimpProjection  *proj);
+
+
+G_DEFINE_TYPE_WITH_CODE (GimpProjection, gimp_projection, GIMP_TYPE_OBJECT,
+                         G_ADD_PRIVATE (GimpProjection)
+                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_PICKABLE,
+                                                gimp_projection_pickable_iface_init))
+
+#define parent_class gimp_projection_parent_class
+
+static guint projection_signals[LAST_SIGNAL] = { 0 };
+
+
+static void
+gimp_projection_class_init (GimpProjectionClass *klass)
+{
+  GObjectClass    *object_class      = G_OBJECT_CLASS (klass);
+  GimpObjectClass *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+
+  projection_signals[UPDATE] =
+    g_signal_new ("update",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpProjectionClass, update),
+                  NULL, NULL,
+                  gimp_marshal_VOID__BOOLEAN_INT_INT_INT_INT,
+                  G_TYPE_NONE, 5,
+                  G_TYPE_BOOLEAN,
+                  G_TYPE_INT,
+                  G_TYPE_INT,
+                  G_TYPE_INT,
+                  G_TYPE_INT);
+
+  object_class->finalize         = gimp_projection_finalize;
+  object_class->set_property     = gimp_projection_set_property;
+  object_class->get_property     = gimp_projection_get_property;
+
+  gimp_object_class->get_memsize = gimp_projection_get_memsize;
+
+  g_object_class_override_property (object_class, PROP_BUFFER, "buffer");
+}
+
+static void
+gimp_projection_init (GimpProjection *proj)
+{
+  proj->priv = gimp_projection_get_instance_private (proj);
+}
+
+static void
+gimp_projection_pickable_iface_init (GimpPickableInterface *iface)
+{
+  iface->flush                 = gimp_projection_pickable_flush;
+  iface->get_image             = gimp_projection_get_image;
+  iface->get_format            = gimp_projection_get_format;
+  iface->get_format_with_alpha = gimp_projection_get_format; /* sic */
+  iface->get_buffer            = gimp_projection_get_buffer;
+  iface->get_pixel_at          = gimp_projection_get_pixel_at;
+  iface->get_opacity_at        = gimp_projection_get_opacity_at;
+  iface->get_pixel_average     = gimp_projection_get_pixel_average;
+  iface->pixel_to_srgb         = gimp_projection_pixel_to_srgb;
+  iface->srgb_to_pixel         = gimp_projection_srgb_to_pixel;
+}
+
+static void
+gimp_projection_finalize (GObject *object)
+{
+  GimpProjection *proj = GIMP_PROJECTION (object);
+
+  gimp_projection_free_buffer (proj);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gimp_projection_set_property (GObject      *object,
+                              guint         property_id,
+                              const GValue *value,
+                              GParamSpec   *pspec)
+{
+  switch (property_id)
+    {
+    case PROP_BUFFER:
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_projection_get_property (GObject    *object,
+                              guint       property_id,
+                              GValue     *value,
+                              GParamSpec *pspec)
+{
+  GimpProjection *projection = GIMP_PROJECTION (object);
+
+  switch (property_id)
+    {
+    case PROP_BUFFER:
+      g_value_set_object (value, projection->priv->buffer);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static gint64
+gimp_projection_get_memsize (GimpObject *object,
+                             gint64     *gui_size)
+{
+  GimpProjection *projection = GIMP_PROJECTION (object);
+  gint64          memsize    = 0;
+
+  memsize += gimp_gegl_pyramid_get_memsize (projection->priv->buffer);
+
+  return memsize + GIMP_OBJECT_CLASS (parent_class)->get_memsize (object,
+                                                                  gui_size);
+}
+
+/**
+ * gimp_projection_estimate_memsize:
+ * @type:           the projectable's base type
+ * @component_type: the projectable's component type
+ * @width:          projection width
+ * @height:         projection height
+ *
+ * Calculates a rough estimate of the memory that is required for the
+ * projection of an image with the given @width and @height.
+ *
+ * Return value: a rough estimate of the memory requirements.
+ **/
+gint64
+gimp_projection_estimate_memsize (GimpImageBaseType type,
+                                  GimpComponentType component_type,
+                                  gint              width,
+                                  gint              height)
+{
+  const Babl *format;
+  gint64      bytes;
+
+  if (type == GIMP_INDEXED)
+    type = GIMP_RGB;
+
+  format = gimp_babl_format (type,
+                             gimp_babl_precision (component_type, FALSE),
+                             TRUE);
+  bytes  = babl_format_get_bytes_per_pixel (format);
+
+  /* The pyramid levels constitute a geometric sum with a ratio of 1/4. */
+  return bytes * (gint64) width * (gint64) height * 1.33;
+}
+
+
+static void
+gimp_projection_pickable_flush (GimpPickable *pickable)
+{
+  GimpProjection *proj = GIMP_PROJECTION (pickable);
+
+  /* create the buffer if it doesn't exist */
+  gimp_projection_get_buffer (pickable);
+
+  gimp_projection_finish_draw (proj);
+  gimp_projection_flush_now (proj, FALSE);
+
+  if (proj->priv->invalidate_preview)
+    {
+      /* invalidate the preview here since it is constructed from
+       * the projection
+       */
+      proj->priv->invalidate_preview = FALSE;
+
+      gimp_projectable_invalidate_preview (proj->priv->projectable);
+    }
+}
+
+static GimpImage *
+gimp_projection_get_image (GimpPickable *pickable)
+{
+  GimpProjection *proj = GIMP_PROJECTION (pickable);
+
+  return gimp_projectable_get_image (proj->priv->projectable);
+}
+
+static const Babl *
+gimp_projection_get_format (GimpPickable *pickable)
+{
+  GimpProjection *proj = GIMP_PROJECTION (pickable);
+
+  return gimp_projectable_get_format (proj->priv->projectable);
+}
+
+static GeglBuffer *
+gimp_projection_get_buffer (GimpPickable *pickable)
+{
+  GimpProjection *proj = GIMP_PROJECTION (pickable);
+
+  if (! proj->priv->buffer)
+    {
+      GeglRectangle bounding_box;
+
+      bounding_box =
+        gimp_projectable_get_bounding_box (proj->priv->projectable);
+
+      gimp_projection_allocate_buffer (proj);
+
+      /*  This used to call gimp_tile_handler_validate_invalidate()
+       *  which forced the entire projection to be constructed in one
+       *  go for new images, causing a potentially huge delay. Now we
+       *  initially validate stuff the normal way, which makes the
+       *  image appear incrementally, but it keeps everything
+       *  responsive.
+       */
+      gimp_projection_add_update_area (proj,
+                                       bounding_box.x,     bounding_box.y,
+                                       bounding_box.width, bounding_box.height);
+      proj->priv->invalidate_preview = TRUE;
+      gimp_projection_flush (proj);
+    }
+
+  return proj->priv->buffer;
+}
+
+static gboolean
+gimp_projection_get_pixel_at (GimpPickable *pickable,
+                              gint          x,
+                              gint          y,
+                              const Babl   *format,
+                              gpointer      pixel)
+{
+  GimpProjection *proj   = GIMP_PROJECTION (pickable);
+  GeglBuffer     *buffer = gimp_projection_get_buffer (pickable);
+  GeglRectangle   bounding_box;
+
+  bounding_box = gimp_projectable_get_bounding_box (proj->priv->projectable);
+
+  if (x <  bounding_box.x                      ||
+      y <  bounding_box.y                      ||
+      x >= bounding_box.x + bounding_box.width ||
+      y >= bounding_box.y + bounding_box.height)
+    {
+      return FALSE;
+    }
+
+  gegl_buffer_sample (buffer, x, y, NULL, pixel, format,
+                      GEGL_SAMPLER_NEAREST, GEGL_ABYSS_NONE);
+
+  return TRUE;
+}
+
+static gdouble
+gimp_projection_get_opacity_at (GimpPickable *pickable,
+                                gint          x,
+                                gint          y)
+{
+  return GIMP_OPACITY_OPAQUE;
+}
+
+static void
+gimp_projection_get_pixel_average (GimpPickable        *pickable,
+                                   const GeglRectangle *rect,
+                                   const Babl          *format,
+                                   gpointer             pixel)
+{
+  GeglBuffer *buffer = gimp_projection_get_buffer (pickable);
+
+  return gimp_gegl_average_color (buffer, rect, TRUE, GEGL_ABYSS_NONE, format,
+                                  pixel);
+}
+
+static void
+gimp_projection_pixel_to_srgb (GimpPickable *pickable,
+                               const Babl   *format,
+                               gpointer      pixel,
+                               GimpRGB      *color)
+{
+  GimpProjection *proj  = GIMP_PROJECTION (pickable);
+  GimpImage      *image = gimp_projectable_get_image (proj->priv->projectable);
+
+  gimp_pickable_pixel_to_srgb (GIMP_PICKABLE (image), format, pixel, color);
+}
+
+static void
+gimp_projection_srgb_to_pixel (GimpPickable  *pickable,
+                               const GimpRGB *color,
+                               const Babl    *format,
+                               gpointer       pixel)
+{
+  GimpProjection *proj  = GIMP_PROJECTION (pickable);
+  GimpImage      *image = gimp_projectable_get_image (proj->priv->projectable);
+
+  gimp_pickable_srgb_to_pixel (GIMP_PICKABLE (image), color, format, pixel);
+}
+
+
+/*  public functions  */
+
+GimpProjection *
+gimp_projection_new (GimpProjectable *projectable)
+{
+  GimpProjection *proj;
+
+  g_return_val_if_fail (GIMP_IS_PROJECTABLE (projectable), NULL);
+
+  proj = g_object_new (GIMP_TYPE_PROJECTION, NULL);
+
+  proj->priv->projectable = projectable;
+
+  g_signal_connect_object (projectable, "invalidate",
+                           G_CALLBACK (gimp_projection_projectable_invalidate),
+                           proj, 0);
+  g_signal_connect_object (projectable, "flush",
+                           G_CALLBACK (gimp_projection_projectable_flush),
+                           proj, 0);
+  g_signal_connect_object (projectable, "structure-changed",
+                           G_CALLBACK (gimp_projection_projectable_structure_changed),
+                           proj, 0);
+  g_signal_connect_object (projectable, "bounds-changed",
+                           G_CALLBACK (gimp_projection_projectable_bounds_changed),
+                           proj, 0);
+
+  return proj;
+}
+
+void
+gimp_projection_set_priority (GimpProjection *proj,
+                              gint            priority)
+{
+  g_return_if_fail (GIMP_IS_PROJECTION (proj));
+
+  proj->priv->priority = priority;
+}
+
+gint
+gimp_projection_get_priority (GimpProjection *proj)
+{
+  g_return_val_if_fail (GIMP_IS_PROJECTION (proj), 0);
+
+  return proj->priv->priority;
+}
+
+void
+gimp_projection_set_priority_rect (GimpProjection *proj,
+                                   gint            x,
+                                   gint            y,
+                                   gint            w,
+                                   gint            h)
+{
+  g_return_if_fail (GIMP_IS_PROJECTION (proj));
+
+  proj->priv->priority_rect = *GEGL_RECTANGLE (x, y, w, h);
+
+  gimp_projection_update_priority_rect (proj);
+}
+
+void
+gimp_projection_stop_rendering (GimpProjection *proj)
+{
+  g_return_if_fail (GIMP_IS_PROJECTION (proj));
+
+  gimp_projection_chunk_render_stop (proj, TRUE);
+}
+
+void
+gimp_projection_flush (GimpProjection *proj)
+{
+  g_return_if_fail (GIMP_IS_PROJECTION (proj));
+
+  /* Construct in chunks */
+  gimp_projection_flush_whenever (proj, FALSE, FALSE);
+}
+
+void
+gimp_projection_flush_now (GimpProjection *proj,
+                           gboolean        direct)
+{
+  g_return_if_fail (GIMP_IS_PROJECTION (proj));
+
+  /* Construct NOW */
+  gimp_projection_flush_whenever (proj, TRUE, direct);
+}
+
+void
+gimp_projection_finish_draw (GimpProjection *proj)
+{
+  g_return_if_fail (GIMP_IS_PROJECTION (proj));
+
+  if (proj->priv->iter)
+    {
+      gimp_chunk_iterator_set_priority_rect (proj->priv->iter, NULL);
+
+      gimp_tile_handler_validate_begin_validate (proj->priv->validate_handler);
+
+      while (gimp_projection_chunk_render_iteration (proj));
+
+      gimp_tile_handler_validate_end_validate (proj->priv->validate_handler);
+
+      gimp_projection_chunk_render_stop (proj, FALSE);
+    }
+}
+
+
+/*  private functions  */
+
+static void
+gimp_projection_allocate_buffer (GimpProjection *proj)
+{
+  const Babl    *format;
+  GeglRectangle  bounding_box;
+
+  if (proj->priv->buffer)
+    return;
+
+  format       = gimp_projection_get_format (GIMP_PICKABLE (proj));
+  bounding_box =
+    gimp_projectable_get_bounding_box (proj->priv->projectable);
+
+  proj->priv->buffer = gegl_buffer_new (&bounding_box, format);
+
+  proj->priv->validate_handler =
+    GIMP_TILE_HANDLER_VALIDATE (
+      gimp_tile_handler_projectable_new (proj->priv->projectable));
+
+  gimp_tile_handler_validate_assign (proj->priv->validate_handler,
+                                     proj->priv->buffer);
+
+  g_object_notify (G_OBJECT (proj), "buffer");
+}
+
+static void
+gimp_projection_free_buffer (GimpProjection  *proj)
+{
+  gimp_projection_chunk_render_stop (proj, FALSE);
+
+  g_clear_pointer (&proj->priv->update_region, cairo_region_destroy);
+
+  if (proj->priv->buffer)
+    {
+      gimp_tile_handler_validate_unassign (proj->priv->validate_handler,
+                                           proj->priv->buffer);
+
+      g_clear_object (&proj->priv->buffer);
+      g_clear_object (&proj->priv->validate_handler);
+
+      g_object_notify (G_OBJECT (proj), "buffer");
+    }
+}
+
+static void
+gimp_projection_add_update_area (GimpProjection *proj,
+                                 gint            x,
+                                 gint            y,
+                                 gint            w,
+                                 gint            h)
+{
+  cairo_rectangle_int_t rect;
+  GeglRectangle         bounding_box;
+
+  bounding_box = gimp_projectable_get_bounding_box (proj->priv->projectable);
+
+  /*  align the rectangle to the UPDATE_CHUNK_WIDTH x UPDATE_CHUNK_HEIGHT grid,
+   *  to decrease the complexity of the update area.
+   */
+  w = ceil  ((gdouble) (x + w) / GIMP_PROJECTION_UPDATE_CHUNK_WIDTH ) * GIMP_PROJECTION_UPDATE_CHUNK_WIDTH;
+  h = ceil  ((gdouble) (y + h) / GIMP_PROJECTION_UPDATE_CHUNK_HEIGHT) * GIMP_PROJECTION_UPDATE_CHUNK_HEIGHT;
+  x = floor ((gdouble) x       / GIMP_PROJECTION_UPDATE_CHUNK_WIDTH ) * GIMP_PROJECTION_UPDATE_CHUNK_WIDTH;
+  y = floor ((gdouble) y       / GIMP_PROJECTION_UPDATE_CHUNK_HEIGHT) * GIMP_PROJECTION_UPDATE_CHUNK_HEIGHT;
+
+  w -= x;
+  h -= y;
+
+  if (gegl_rectangle_intersect ((GeglRectangle *) &rect,
+                                GEGL_RECTANGLE (x, y, w, h), &bounding_box))
+    {
+      if (proj->priv->update_region)
+        cairo_region_union_rectangle (proj->priv->update_region, &rect);
+      else
+        proj->priv->update_region = cairo_region_create_rectangle (&rect);
+    }
+}
+
+static void
+gimp_projection_flush_whenever (GimpProjection *proj,
+                                gboolean        now,
+                                gboolean        direct)
+{
+  if (proj->priv->update_region)
+    {
+      /* Make sure we have a buffer */
+      gimp_projection_allocate_buffer (proj);
+
+      if (now)  /* Synchronous */
+        {
+          gint n_rects = cairo_region_num_rectangles (proj->priv->update_region);
+          gint i;
+
+          for (i = 0; i < n_rects; i++)
+            {
+              cairo_rectangle_int_t rect;
+
+              cairo_region_get_rectangle (proj->priv->update_region,
+                                          i, &rect);
+
+              gimp_projection_paint_area (proj,
+                                          direct,
+                                          rect.x,
+                                          rect.y,
+                                          rect.width,
+                                          rect.height);
+            }
+
+          /*  Free the update region  */
+          g_clear_pointer (&proj->priv->update_region, cairo_region_destroy);
+        }
+      else  /* Asynchronous */
+        {
+          /*  Consumes the update region  */
+          gimp_projection_chunk_render_start (proj);
+        }
+    }
+  else if (! now && ! proj->priv->iter && proj->priv->invalidate_preview)
+    {
+      /* invalidate the preview here since it is constructed from
+       * the projection
+       */
+      proj->priv->invalidate_preview = FALSE;
+
+      gimp_projectable_invalidate_preview (proj->priv->projectable);
+    }
+}
+
+static void
+gimp_projection_update_priority_rect (GimpProjection *proj)
+{
+  if (proj->priv->iter)
+    {
+      GeglRectangle rect;
+      GeglRectangle bounding_box;
+      gint          off_x, off_y;
+
+      rect = proj->priv->priority_rect;
+
+      gimp_projectable_get_offset (proj->priv->projectable, &off_x, &off_y);
+      bounding_box = gimp_projectable_get_bounding_box (proj->priv->projectable);
+
+      /*  subtract the projectable's offsets because the list of update
+       *  areas is in tile-pyramid coordinates, but our external API is
+       *  always in terms of image coordinates.
+       */
+      rect.x -= off_x;
+      rect.y -= off_y;
+
+      gegl_rectangle_intersect (&rect, &rect, &bounding_box);
+
+      gimp_chunk_iterator_set_priority_rect (proj->priv->iter, &rect);
+    }
+}
+
+static void
+gimp_projection_chunk_render_start (GimpProjection *proj)
+{
+  cairo_region_t *region             = proj->priv->update_region;
+  gboolean        invalidate_preview = FALSE;
+
+  if (proj->priv->iter)
+    {
+      region = gimp_chunk_iterator_stop (proj->priv->iter, FALSE);
+
+      proj->priv->iter = NULL;
+
+      if (cairo_region_is_empty (region))
+        invalidate_preview = proj->priv->invalidate_preview;
+
+      if (proj->priv->update_region)
+        {
+          cairo_region_union (region, proj->priv->update_region);
+
+          cairo_region_destroy (proj->priv->update_region);
+        }
+    }
+
+  proj->priv->update_region = NULL;
+
+  if (region && ! cairo_region_is_empty (region))
+    {
+      proj->priv->iter = gimp_chunk_iterator_new (region);
+
+      gimp_projection_update_priority_rect (proj);
+
+      if (! proj->priv->idle_id)
+        {
+          proj->priv->idle_id = g_idle_add_full (
+            GIMP_PRIORITY_PROJECTION_IDLE + proj->priv->priority,
+            (GSourceFunc) gimp_projection_chunk_render_callback,
+            proj, NULL);
+        }
+    }
+  else
+    {
+      if (region)
+        cairo_region_destroy (region);
+
+      if (proj->priv->idle_id)
+        {
+          g_source_remove (proj->priv->idle_id);
+          proj->priv->idle_id = 0;
+        }
+
+      if (invalidate_preview)
+        {
+          /* invalidate the preview here since it is constructed from
+           * the projection
+           */
+          proj->priv->invalidate_preview = FALSE;
+
+          gimp_projectable_invalidate_preview (proj->priv->projectable);
+        }
+    }
+}
+
+static void
+gimp_projection_chunk_render_stop (GimpProjection *proj,
+                                   gboolean        merge)
+{
+  if (proj->priv->idle_id)
+    {
+      g_source_remove (proj->priv->idle_id);
+      proj->priv->idle_id = 0;
+    }
+
+  if (proj->priv->iter)
+    {
+      if (merge)
+        {
+          cairo_region_t *region;
+
+          region = gimp_chunk_iterator_stop (proj->priv->iter, FALSE);
+
+          if (proj->priv->update_region)
+            {
+              cairo_region_union (proj->priv->update_region, region);
+
+              cairo_region_destroy (region);
+            }
+          else
+            {
+              proj->priv->update_region = region;
+            }
+        }
+      else
+        {
+          gimp_chunk_iterator_stop (proj->priv->iter, TRUE);
+        }
+
+      proj->priv->iter = NULL;
+    }
+}
+
+static gboolean
+gimp_projection_chunk_render_callback (GimpProjection *proj)
+{
+  if (gimp_projection_chunk_render_iteration (proj))
+    {
+      return G_SOURCE_CONTINUE;
+    }
+  else
+    {
+      proj->priv->idle_id = 0;
+
+      return G_SOURCE_REMOVE;
+    }
+}
+
+static gboolean
+gimp_projection_chunk_render_iteration (GimpProjection *proj)
+{
+  if (gimp_chunk_iterator_next (proj->priv->iter))
+    {
+      GeglRectangle rect;
+
+      gimp_tile_handler_validate_begin_validate (proj->priv->validate_handler);
+
+      while (gimp_chunk_iterator_get_rect (proj->priv->iter, &rect))
+        {
+          gimp_projection_paint_area (proj, TRUE,
+                                      rect.x, rect.y, rect.width, rect.height);
+        }
+
+      gimp_tile_handler_validate_end_validate (proj->priv->validate_handler);
+
+      /* Still work to do. */
+      return TRUE;
+    }
+  else
+    {
+      proj->priv->iter = NULL;
+
+      if (proj->priv->invalidate_preview)
+        {
+          /* invalidate the preview here since it is constructed from
+           * the projection
+           */
+          proj->priv->invalidate_preview = FALSE;
+
+          gimp_projectable_invalidate_preview (proj->priv->projectable);
+        }
+
+      /* FINISHED */
+      return FALSE;
+    }
+}
+
+static void
+gimp_projection_paint_area (GimpProjection *proj,
+                            gboolean        now,
+                            gint            x,
+                            gint            y,
+                            gint            w,
+                            gint            h)
+{
+  gint          off_x, off_y;
+  GeglRectangle bounding_box;
+  GeglRectangle rect;
+
+  gimp_projectable_get_offset (proj->priv->projectable, &off_x, &off_y);
+  bounding_box = gimp_projectable_get_bounding_box (proj->priv->projectable);
+
+  if (gegl_rectangle_intersect (&rect,
+                                GEGL_RECTANGLE (x, y, w, h), &bounding_box))
+    {
+      if (now)
+        {
+          gimp_tile_handler_validate_validate (
+            proj->priv->validate_handler,
+            proj->priv->buffer,
+            &rect,
+            FALSE, FALSE);
+        }
+      else
+        {
+          gimp_tile_handler_validate_invalidate (
+            proj->priv->validate_handler,
+            &rect);
+        }
+
+      /*  add the projectable's offsets because the list of update areas
+       *  is in tile-pyramid coordinates, but our external API is always
+       *  in terms of image coordinates.
+       */
+      g_signal_emit (proj, projection_signals[UPDATE], 0,
+                     now,
+                     rect.x + off_x,
+                     rect.y + off_y,
+                     rect.width,
+                     rect.height);
+    }
+}
+
+
+/*  image callbacks  */
+
+static void
+gimp_projection_projectable_invalidate (GimpProjectable *projectable,
+                                        gint             x,
+                                        gint             y,
+                                        gint             w,
+                                        gint             h,
+                                        GimpProjection  *proj)
+{
+  gint off_x, off_y;
+
+  gimp_projectable_get_offset (proj->priv->projectable, &off_x, &off_y);
+
+  /*  subtract the projectable's offsets because the list of update
+   *  areas is in tile-pyramid coordinates, but our external API is
+   *  always in terms of image coordinates.
+   */
+  x -= off_x;
+  y -= off_y;
+
+  gimp_projection_add_update_area (proj, x, y, w, h);
+}
+
+static void
+gimp_projection_projectable_flush (GimpProjectable *projectable,
+                                   gboolean         invalidate_preview,
+                                   GimpProjection  *proj)
+{
+  if (invalidate_preview)
+    proj->priv->invalidate_preview = TRUE;
+
+  gimp_projection_flush (proj);
+}
+
+static void
+gimp_projection_projectable_structure_changed (GimpProjectable *projectable,
+                                               GimpProjection  *proj)
+{
+  GeglRectangle bounding_box;
+
+  gimp_projection_free_buffer (proj);
+
+  bounding_box = gimp_projectable_get_bounding_box (projectable);
+
+  gimp_projection_add_update_area (proj,
+                                   bounding_box.x,     bounding_box.y,
+                                   bounding_box.width, bounding_box.height);
+}
+
+static void
+gimp_projection_projectable_bounds_changed (GimpProjectable *projectable,
+                                            gint             old_x,
+                                            gint             old_y,
+                                            GimpProjection  *proj)
+{
+  GeglBuffer              *old_buffer = proj->priv->buffer;
+  GimpTileHandlerValidate *old_validate_handler;
+  GeglRectangle            old_bounding_box;
+  GeglRectangle            bounding_box;
+  GeglRectangle            old_bounds;
+  GeglRectangle            bounds;
+  GeglRectangle            int_bounds;
+  gint                     x, y;
+  gint                     dx, dy;
+
+  if (! old_buffer)
+    {
+      gimp_projection_projectable_structure_changed (projectable, proj);
+
+      return;
+    }
+
+  old_bounding_box = *gegl_buffer_get_extent (old_buffer);
+
+  gimp_projectable_get_offset (projectable, &x, &y);
+  bounding_box = gimp_projectable_get_bounding_box (projectable);
+
+  if (x == old_x && y == old_y &&
+      gegl_rectangle_equal (&bounding_box, &old_bounding_box))
+    {
+      return;
+    }
+
+  old_bounds    = old_bounding_box;
+  old_bounds.x += old_x;
+  old_bounds.y += old_y;
+
+  bounds        = bounding_box;
+  bounds.x     += x;
+  bounds.y     += y;
+
+  if (! gegl_rectangle_intersect (&int_bounds, &bounds, &old_bounds))
+    {
+      gimp_projection_projectable_structure_changed (projectable, proj);
+
+      return;
+    }
+
+  dx = x - old_x;
+  dy = y - old_y;
+
+#if 1
+  /* FIXME:  when there's an offset between the new bounds and the old bounds,
+   * use gimp_projection_projectable_structure_changed(), instead of copying a
+   * shifted version of the old buffer, since the synchronous copy can take a
+   * notable amount of time for big buffers, when the offset is such that tiles
+   * are not COW-ed.  while gimp_projection_projectable_structure_changed()
+   * causes the projection to be re-rendered, which is overall slower, it's
+   * done asynchronously.
+   *
+   * this needs to be improved.
+   */
+  if (dx || dy)
+    {
+      gimp_projection_projectable_structure_changed (projectable, proj);
+
+      return;
+    }
+#endif
+
+  /* reallocate the buffer, and copy the old buffer to the corresponding
+   * region of the new buffer.
+   */
+
+  gimp_projection_chunk_render_stop (proj, TRUE);
+
+  if (dx == 0 && dy == 0)
+    {
+      gimp_tile_handler_validate_buffer_set_extent (old_buffer, &bounding_box);
+    }
+  else
+    {
+      old_validate_handler = proj->priv->validate_handler;
+
+      proj->priv->buffer           = NULL;
+      proj->priv->validate_handler = NULL;
+
+      gimp_projection_allocate_buffer (proj);
+
+      gimp_tile_handler_validate_buffer_copy (
+        old_buffer,
+        GEGL_RECTANGLE (int_bounds.x - old_x,
+                        int_bounds.y - old_y,
+                        int_bounds.width,
+                        int_bounds.height),
+        proj->priv->buffer,
+        GEGL_RECTANGLE (int_bounds.x - x,
+                        int_bounds.y - y,
+                        int_bounds.width,
+                        int_bounds.height));
+
+      gimp_tile_handler_validate_unassign (old_validate_handler,
+                                           old_buffer);
+
+      g_object_unref (old_validate_handler);
+      g_object_unref (old_buffer);
+    }
+
+  if (proj->priv->update_region)
+    {
+      cairo_region_translate (proj->priv->update_region, dx, dy);
+      cairo_region_intersect_rectangle (
+        proj->priv->update_region,
+        (const cairo_rectangle_int_t *) &bounding_box);
+    }
+
+  int_bounds.x -= x;
+  int_bounds.y -= y;
+
+  if (int_bounds.x > bounding_box.x)
+    {
+      gimp_projection_add_update_area (proj,
+                                       bounding_box.x,
+                                       bounding_box.y,
+                                       int_bounds.x - bounding_box.x,
+                                       bounding_box.height);
+    }
+  if (int_bounds.y > bounding_box.y)
+    {
+      gimp_projection_add_update_area (proj,
+                                       bounding_box.x,
+                                       bounding_box.y,
+                                       bounding_box.width,
+                                       int_bounds.y - bounding_box.y);
+    }
+  if (int_bounds.x + int_bounds.width < bounding_box.x + bounding_box.width)
+    {
+      gimp_projection_add_update_area (proj,
+                                       int_bounds.x + int_bounds.width,
+                                       bounding_box.y,
+                                       bounding_box.x + bounding_box.width -
+                                       (int_bounds.x  + int_bounds.width),
+                                       bounding_box.height);
+    }
+  if (int_bounds.y + int_bounds.height < bounding_box.y + bounding_box.height)
+    {
+      gimp_projection_add_update_area (proj,
+                                       bounding_box.x,
+                                       int_bounds.y + int_bounds.height,
+                                       bounding_box.width,
+                                       bounding_box.y + bounding_box.height -
+                                       (int_bounds.y  + int_bounds.height));
+    }
+
+  proj->priv->invalidate_preview = TRUE;
+}
diff --git a/app/core/gimpprojection.h b/app/core/gimpprojection.h
new file mode 100644
index 0000000..8c9baf6
--- /dev/null
+++ b/app/core/gimpprojection.h
@@ -0,0 +1,83 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_PROJECTION_H__
+#define __GIMP_PROJECTION_H__
+
+
+#include "gimpobject.h"
+
+
+#define GIMP_TYPE_PROJECTION            (gimp_projection_get_type ())
+#define GIMP_PROJECTION(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_PROJECTION, GimpProjection))
+#define GIMP_PROJECTION_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_PROJECTION, GimpProjectionClass))
+#define GIMP_IS_PROJECTION(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_PROJECTION))
+#define GIMP_IS_PROJECTION_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_PROJECTION))
+#define GIMP_PROJECTION_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_PROJECTION, GimpProjectionClass))
+
+
+typedef struct _GimpProjectionPrivate GimpProjectionPrivate;
+typedef struct _GimpProjectionClass   GimpProjectionClass;
+
+struct _GimpProjection
+{
+  GimpObject             parent_instance;
+
+  GimpProjectionPrivate *priv;
+};
+
+struct _GimpProjectionClass
+{
+  GimpObjectClass  parent_class;
+
+  void (* update) (GimpProjection *proj,
+                   gboolean        now,
+                   gint            x,
+                   gint            y,
+                   gint            width,
+                   gint            height);
+};
+
+
+GType            gimp_projection_get_type          (void) G_GNUC_CONST;
+
+GimpProjection * gimp_projection_new               (GimpProjectable   *projectable);
+
+void             gimp_projection_set_priority      (GimpProjection    *projection,
+                                                    gint               priority);
+gint             gimp_projection_get_priority      (GimpProjection    *projection);
+
+void             gimp_projection_set_priority_rect (GimpProjection    *proj,
+                                                    gint               x,
+                                                    gint               y,
+                                                    gint               width,
+                                                    gint               height);
+
+void             gimp_projection_stop_rendering    (GimpProjection    *proj);
+
+void             gimp_projection_flush             (GimpProjection    *proj);
+void             gimp_projection_flush_now         (GimpProjection    *proj,
+                                                    gboolean           direct);
+void             gimp_projection_finish_draw       (GimpProjection    *proj);
+
+gint64           gimp_projection_estimate_memsize  (GimpImageBaseType  type,
+                                                    GimpComponentType  component_type,
+                                                    gint               width,
+                                                    gint               height);
+
+
+#endif /*  __GIMP_PROJECTION_H__  */
diff --git a/app/core/gimpsamplepoint.c b/app/core/gimpsamplepoint.c
new file mode 100644
index 0000000..f0fe377
--- /dev/null
+++ b/app/core/gimpsamplepoint.c
@@ -0,0 +1,215 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gio/gio.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpconfig/gimpconfig.h"
+
+#include "core-types.h"
+
+#include "gimpsamplepoint.h"
+
+
+enum
+{
+  PROP_0,
+  PROP_POSITION_X,
+  PROP_POSITION_Y,
+  PROP_PICK_MODE
+};
+
+
+struct _GimpSamplePointPrivate
+{
+  gint              position_x;
+  gint              position_y;
+  GimpColorPickMode pick_mode;
+};
+
+
+static void   gimp_sample_point_get_property (GObject      *object,
+                                              guint         property_id,
+                                              GValue       *value,
+                                              GParamSpec   *pspec);
+static void   gimp_sample_point_set_property (GObject      *object,
+                                              guint         property_id,
+                                              const GValue *value,
+                                              GParamSpec   *pspec);
+
+
+G_DEFINE_TYPE_WITH_PRIVATE (GimpSamplePoint, gimp_sample_point,
+                            GIMP_TYPE_AUX_ITEM)
+
+
+static void
+gimp_sample_point_class_init (GimpSamplePointClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  object_class->get_property = gimp_sample_point_get_property;
+  object_class->set_property = gimp_sample_point_set_property;
+
+  GIMP_CONFIG_PROP_INT (object_class, PROP_POSITION_X,
+                        "position-x",
+                        NULL, NULL,
+                        GIMP_SAMPLE_POINT_POSITION_UNDEFINED,
+                        GIMP_MAX_IMAGE_SIZE,
+                        GIMP_SAMPLE_POINT_POSITION_UNDEFINED,
+                        0);
+
+  GIMP_CONFIG_PROP_INT (object_class, PROP_POSITION_Y,
+                        "position-y",
+                        NULL, NULL,
+                        GIMP_SAMPLE_POINT_POSITION_UNDEFINED,
+                        GIMP_MAX_IMAGE_SIZE,
+                        GIMP_SAMPLE_POINT_POSITION_UNDEFINED,
+                        0);
+
+  GIMP_CONFIG_PROP_ENUM (object_class, PROP_PICK_MODE,
+                         "pick-mode",
+                         NULL, NULL,
+                         GIMP_TYPE_COLOR_PICK_MODE,
+                         GIMP_COLOR_PICK_MODE_PIXEL,
+                         0);
+}
+
+static void
+gimp_sample_point_init (GimpSamplePoint *sample_point)
+{
+  sample_point->priv = gimp_sample_point_get_instance_private (sample_point);
+}
+
+static void
+gimp_sample_point_get_property (GObject    *object,
+                                guint       property_id,
+                                GValue     *value,
+                                GParamSpec *pspec)
+{
+  GimpSamplePoint *sample_point = GIMP_SAMPLE_POINT (object);
+
+  switch (property_id)
+    {
+    case PROP_POSITION_X:
+      g_value_set_int (value, sample_point->priv->position_x);
+      break;
+    case PROP_POSITION_Y:
+      g_value_set_int (value, sample_point->priv->position_y);
+      break;
+    case PROP_PICK_MODE:
+      g_value_set_enum (value, sample_point->priv->pick_mode);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_sample_point_set_property (GObject      *object,
+                                guint         property_id,
+                                const GValue *value,
+                                GParamSpec   *pspec)
+{
+  GimpSamplePoint *sample_point = GIMP_SAMPLE_POINT (object);
+
+  switch (property_id)
+    {
+    case PROP_POSITION_X:
+      sample_point->priv->position_x = g_value_get_int (value);
+      break;
+    case PROP_POSITION_Y:
+      sample_point->priv->position_y = g_value_get_int (value);
+      break;
+    case PROP_PICK_MODE:
+      sample_point->priv->pick_mode = g_value_get_enum (value);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+GimpSamplePoint *
+gimp_sample_point_new (guint32 sample_point_ID)
+{
+  return g_object_new (GIMP_TYPE_SAMPLE_POINT,
+                       "id", sample_point_ID,
+                       NULL);
+}
+
+void
+gimp_sample_point_get_position (GimpSamplePoint *sample_point,
+                                gint            *position_x,
+                                gint            *position_y)
+{
+  g_return_if_fail (GIMP_IS_SAMPLE_POINT (sample_point));
+  g_return_if_fail (position_x != NULL);
+  g_return_if_fail (position_y != NULL);
+
+  *position_x = sample_point->priv->position_x;
+  *position_y = sample_point->priv->position_y;
+}
+
+void
+gimp_sample_point_set_position (GimpSamplePoint *sample_point,
+                                gint             position_x,
+                                gint             position_y)
+{
+  g_return_if_fail (GIMP_IS_SAMPLE_POINT (sample_point));
+
+  if (sample_point->priv->position_x != position_x ||
+      sample_point->priv->position_y != position_y)
+    {
+      sample_point->priv->position_x = position_x;
+      sample_point->priv->position_y = position_y;
+
+      g_object_freeze_notify (G_OBJECT (sample_point));
+
+      g_object_notify (G_OBJECT (sample_point), "position-x");
+      g_object_notify (G_OBJECT (sample_point), "position-y");
+
+      g_object_thaw_notify (G_OBJECT (sample_point));
+    }
+}
+
+GimpColorPickMode
+gimp_sample_point_get_pick_mode (GimpSamplePoint *sample_point)
+{
+  g_return_val_if_fail (GIMP_IS_SAMPLE_POINT (sample_point),
+                        GIMP_COLOR_PICK_MODE_PIXEL);
+
+  return sample_point->priv->pick_mode;
+}
+
+void
+gimp_sample_point_set_pick_mode (GimpSamplePoint   *sample_point,
+                                 GimpColorPickMode  pick_mode)
+{
+  g_return_if_fail (GIMP_IS_SAMPLE_POINT (sample_point));
+
+  if (sample_point->priv->pick_mode != pick_mode)
+    {
+      sample_point->priv->pick_mode = pick_mode;
+
+      g_object_notify (G_OBJECT (sample_point), "pick-mode");
+    }
+}
diff --git a/app/core/gimpsamplepoint.h b/app/core/gimpsamplepoint.h
new file mode 100644
index 0000000..dddd328
--- /dev/null
+++ b/app/core/gimpsamplepoint.h
@@ -0,0 +1,68 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_SAMPLE_POINT_H__
+#define __GIMP_SAMPLE_POINT_H__
+
+
+#include "gimpauxitem.h"
+
+
+#define GIMP_SAMPLE_POINT_POSITION_UNDEFINED G_MININT
+
+
+#define GIMP_TYPE_SAMPLE_POINT            (gimp_sample_point_get_type ())
+#define GIMP_SAMPLE_POINT(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_SAMPLE_POINT, GimpSamplePoint))
+#define GIMP_SAMPLE_POINT_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_SAMPLE_POINT, GimpSamplePointClass))
+#define GIMP_IS_SAMPLE_POINT(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_SAMPLE_POINT))
+#define GIMP_IS_SAMPLE_POINT_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_SAMPLE_POINT))
+#define GIMP_SAMPLE_POINT_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_SAMPLE_POINT, GimpSamplePointClass))
+
+
+typedef struct _GimpSamplePointPrivate GimpSamplePointPrivate;
+typedef struct _GimpSamplePointClass   GimpSamplePointClass;
+
+struct _GimpSamplePoint
+{
+  GimpAuxItem             parent_instance;
+
+  GimpSamplePointPrivate *priv;
+};
+
+struct _GimpSamplePointClass
+{
+  GimpAuxItemClass  parent_class;
+};
+
+
+GType             gimp_sample_point_get_type      (void) G_GNUC_CONST;
+
+GimpSamplePoint * gimp_sample_point_new           (guint32            sample_point_ID);
+
+void              gimp_sample_point_get_position  (GimpSamplePoint   *sample_point,
+                                                   gint              *position_x,
+                                                   gint              *position_y);
+void              gimp_sample_point_set_position  (GimpSamplePoint   *sample_point,
+                                                   gint               position_x,
+                                                   gint               position_y);
+
+GimpColorPickMode gimp_sample_point_get_pick_mode (GimpSamplePoint   *sample_point);
+void              gimp_sample_point_set_pick_mode (GimpSamplePoint   *sample_point,
+                                                   GimpColorPickMode  pick_mode);
+
+
+#endif /* __GIMP_SAMPLE_POINT_H__ */
diff --git a/app/core/gimpsamplepointundo.c b/app/core/gimpsamplepointundo.c
new file mode 100644
index 0000000..89cd8ae
--- /dev/null
+++ b/app/core/gimpsamplepointundo.c
@@ -0,0 +1,121 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gimpimage.h"
+#include "gimpimage-sample-points.h"
+#include "gimpsamplepoint.h"
+#include "gimpsamplepointundo.h"
+
+
+static void   gimp_sample_point_undo_constructed  (GObject             *object);
+
+static void   gimp_sample_point_undo_pop          (GimpUndo            *undo,
+                                                   GimpUndoMode         undo_mode,
+                                                   GimpUndoAccumulator *accum);
+
+
+G_DEFINE_TYPE (GimpSamplePointUndo, gimp_sample_point_undo,
+               GIMP_TYPE_AUX_ITEM_UNDO)
+
+#define parent_class gimp_sample_point_undo_parent_class
+
+
+static void
+gimp_sample_point_undo_class_init (GimpSamplePointUndoClass *klass)
+{
+  GObjectClass  *object_class = G_OBJECT_CLASS (klass);
+  GimpUndoClass *undo_class   = GIMP_UNDO_CLASS (klass);
+
+  object_class->constructed = gimp_sample_point_undo_constructed;
+
+  undo_class->pop           = gimp_sample_point_undo_pop;
+}
+
+static void
+gimp_sample_point_undo_init (GimpSamplePointUndo *undo)
+{
+}
+
+static void
+gimp_sample_point_undo_constructed (GObject *object)
+{
+  GimpSamplePointUndo *sample_point_undo = GIMP_SAMPLE_POINT_UNDO (object);
+  GimpSamplePoint     *sample_point;
+
+  G_OBJECT_CLASS (parent_class)->constructed (object);
+
+  sample_point = GIMP_SAMPLE_POINT (GIMP_AUX_ITEM_UNDO (object)->aux_item);
+
+  gimp_assert (GIMP_IS_SAMPLE_POINT (sample_point));
+
+  gimp_sample_point_get_position (sample_point,
+                                  &sample_point_undo->x,
+                                  &sample_point_undo->y);
+  sample_point_undo->pick_mode = gimp_sample_point_get_pick_mode (sample_point);
+}
+
+static void
+gimp_sample_point_undo_pop (GimpUndo              *undo,
+                            GimpUndoMode           undo_mode,
+                            GimpUndoAccumulator   *accum)
+{
+  GimpSamplePointUndo *sample_point_undo = GIMP_SAMPLE_POINT_UNDO (undo);
+  GimpSamplePoint     *sample_point;
+  gint                 x;
+  gint                 y;
+  GimpColorPickMode    pick_mode;
+
+  GIMP_UNDO_CLASS (parent_class)->pop (undo, undo_mode, accum);
+
+  sample_point = GIMP_SAMPLE_POINT (GIMP_AUX_ITEM_UNDO (undo)->aux_item);
+
+  gimp_sample_point_get_position (sample_point, &x, &y);
+  pick_mode = gimp_sample_point_get_pick_mode (sample_point);
+
+  if (x == GIMP_SAMPLE_POINT_POSITION_UNDEFINED)
+    {
+      gimp_image_add_sample_point (undo->image,
+                                   sample_point,
+                                   sample_point_undo->x,
+                                   sample_point_undo->y);
+    }
+  else if (sample_point_undo->x == GIMP_SAMPLE_POINT_POSITION_UNDEFINED)
+    {
+      gimp_image_remove_sample_point (undo->image, sample_point, FALSE);
+    }
+  else
+    {
+      gimp_sample_point_set_position (sample_point,
+                                      sample_point_undo->x,
+                                      sample_point_undo->y);
+      gimp_sample_point_set_pick_mode (sample_point,
+                                       sample_point_undo->pick_mode);
+
+      gimp_image_sample_point_moved (undo->image, sample_point);
+    }
+
+  sample_point_undo->x         = x;
+  sample_point_undo->y         = y;
+  sample_point_undo->pick_mode = pick_mode;
+}
diff --git a/app/core/gimpsamplepointundo.h b/app/core/gimpsamplepointundo.h
new file mode 100644
index 0000000..10a3e90
--- /dev/null
+++ b/app/core/gimpsamplepointundo.h
@@ -0,0 +1,54 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_SAMPLE_POINT_UNDO_H__
+#define __GIMP_SAMPLE_POINT_UNDO_H__
+
+
+#include "gimpauxitemundo.h"
+
+
+#define GIMP_TYPE_SAMPLE_POINT_UNDO            (gimp_sample_point_undo_get_type ())
+#define GIMP_SAMPLE_POINT_UNDO(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_SAMPLE_POINT_UNDO, GimpSamplePointUndo))
+#define GIMP_SAMPLE_POINT_UNDO_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_SAMPLE_POINT_UNDO, GimpSamplePointUndoClass))
+#define GIMP_IS_SAMPLE_POINT_UNDO(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_SAMPLE_POINT_UNDO))
+#define GIMP_IS_SAMPLE_POINT_UNDO_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_SAMPLE_POINT_UNDO))
+#define GIMP_SAMPLE_POINT_UNDO_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_SAMPLE_POINT_UNDO, GimpSamplePointUndoClass))
+
+
+typedef struct _GimpSamplePointUndo      GimpSamplePointUndo;
+typedef struct _GimpSamplePointUndoClass GimpSamplePointUndoClass;
+
+struct _GimpSamplePointUndo
+{
+  GimpAuxItemUndo    parent_instance;
+
+  gint               x;
+  gint               y;
+  GimpColorPickMode  pick_mode;
+};
+
+struct _GimpSamplePointUndoClass
+{
+  GimpAuxItemUndoClass  parent_class;
+};
+
+
+GType   gimp_sample_point_undo_get_type (void) G_GNUC_CONST;
+
+
+#endif /* __GIMP_SAMPLE_POINT_UNDO_H__ */
diff --git a/app/core/gimpscanconvert.c b/app/core/gimpscanconvert.c
new file mode 100644
index 0000000..ed5859c
--- /dev/null
+++ b/app/core/gimpscanconvert.c
@@ -0,0 +1,647 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1999 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include <cairo.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpmath/gimpmath.h"
+
+#include "core-types.h"
+
+#include "gimpboundary.h"
+#include "gimpbezierdesc.h"
+#include "gimpscanconvert.h"
+
+
+struct _GimpScanConvert
+{
+  gdouble         ratio_xy;
+
+  gboolean        clip;
+  gint            clip_x;
+  gint            clip_y;
+  gint            clip_w;
+  gint            clip_h;
+
+  /* stroking options */
+  gboolean        do_stroke;
+  gdouble         width;
+  GimpJoinStyle   join;
+  GimpCapStyle    cap;
+  gdouble         miter;
+  gdouble         dash_offset;
+  GArray         *dash_info;
+
+  GArray         *path_data;
+};
+
+
+/*  public functions  */
+
+/**
+ * gimp_scan_convert_new:
+ *
+ * Create a new scan conversion context.
+ *
+ * Return value: a newly allocated #GimpScanConvert context.
+ */
+GimpScanConvert *
+gimp_scan_convert_new (void)
+{
+  GimpScanConvert *sc = g_slice_new0 (GimpScanConvert);
+
+  sc->path_data = g_array_new (FALSE, FALSE, sizeof (cairo_path_data_t));
+  sc->ratio_xy = 1.0;
+
+  return sc;
+}
+
+GimpScanConvert *
+gimp_scan_convert_new_from_boundary (const GimpBoundSeg *bound_segs,
+                                     gint                n_bound_segs,
+                                     gint                offset_x,
+                                     gint                offset_y)
+{
+  g_return_val_if_fail (bound_segs == NULL || n_bound_segs != 0, NULL);
+
+  if (bound_segs)
+    {
+      GimpBoundSeg *stroke_segs;
+      gint          n_stroke_segs;
+
+      stroke_segs = gimp_boundary_sort (bound_segs, n_bound_segs,
+                                        &n_stroke_segs);
+
+      if (stroke_segs)
+        {
+          GimpBezierDesc *bezier;
+
+          bezier = gimp_bezier_desc_new_from_bound_segs (stroke_segs,
+                                                         n_bound_segs,
+                                                         n_stroke_segs);
+
+          g_free (stroke_segs);
+
+          if (bezier)
+            {
+              GimpScanConvert *scan_convert;
+
+              scan_convert = gimp_scan_convert_new ();
+
+              gimp_bezier_desc_translate (bezier, offset_x, offset_y);
+              gimp_scan_convert_add_bezier (scan_convert, bezier);
+
+              gimp_bezier_desc_free (bezier);
+
+              return scan_convert;
+            }
+        }
+    }
+
+  return NULL;
+}
+
+/**
+ * gimp_scan_convert_free:
+ * @sc: a #GimpScanConvert context
+ *
+ * Frees the resources allocated for @sc.
+ */
+void
+gimp_scan_convert_free (GimpScanConvert *sc)
+{
+  g_return_if_fail (sc != NULL);
+
+  if (sc->path_data)
+    g_array_free (sc->path_data, TRUE);
+
+  if (sc->dash_info)
+    g_array_free (sc->dash_info, TRUE);
+
+  g_slice_free (GimpScanConvert, sc);
+}
+
+/**
+ * gimp_scan_convert_set_pixel_ratio:
+ * @sc:       a #GimpScanConvert context
+ * @ratio_xy: the aspect ratio of the major coordinate axes
+ *
+ * Sets the pixel aspect ratio.
+ */
+void
+gimp_scan_convert_set_pixel_ratio (GimpScanConvert *sc,
+                                   gdouble          ratio_xy)
+{
+  g_return_if_fail (sc != NULL);
+
+  /* we only need the relative resolution */
+  sc->ratio_xy = ratio_xy;
+}
+
+/**
+ * gimp_scan_convert_set_clip_rectangle
+ * @sc:     a #GimpScanConvert context
+ * @x:      horizontal offset of clip rectangle
+ * @y:      vertical offset of clip rectangle
+ * @width:  width of clip rectangle
+ * @height: height of clip rectangle
+ *
+ * Sets a clip rectangle on @sc. Subsequent render operations will be
+ * restricted to this area.
+ */
+void
+gimp_scan_convert_set_clip_rectangle (GimpScanConvert *sc,
+                                      gint             x,
+                                      gint             y,
+                                      gint             width,
+                                      gint             height)
+{
+  g_return_if_fail (sc != NULL);
+
+  sc->clip   = TRUE;
+  sc->clip_x = x;
+  sc->clip_y = y;
+  sc->clip_w = width;
+  sc->clip_h = height;
+}
+
+/**
+ * gimp_scan_convert_add_polyline:
+ * @sc:       a #GimpScanConvert context
+ * @n_points: number of points to add
+ * @points:   array of points to add
+ * @closed:   whether to close the polyline and make it a polygon
+ *
+ * Add a polyline with @n_points @points that may be open or closed.
+ *
+ * Please note that you should use gimp_scan_convert_stroke() if you
+ * specify open polygons.
+ */
+void
+gimp_scan_convert_add_polyline (GimpScanConvert   *sc,
+                                guint              n_points,
+                                const GimpVector2 *points,
+                                gboolean           closed)
+{
+  GimpVector2        prev = { 0.0, 0.0, };
+  cairo_path_data_t  pd;
+  gint               i;
+
+  g_return_if_fail (sc != NULL);
+  g_return_if_fail (points != NULL);
+  g_return_if_fail (n_points > 0);
+
+  for (i = 0; i < n_points; i++)
+    {
+      /* compress multiple identical coordinates */
+      if (i == 0 ||
+          prev.x != points[i].x ||
+          prev.y != points[i].y)
+        {
+          pd.header.type = (i == 0) ? CAIRO_PATH_MOVE_TO : CAIRO_PATH_LINE_TO;
+          pd.header.length = 2;
+          sc->path_data = g_array_append_val (sc->path_data, pd);
+
+          pd.point.x = points[i].x;
+          pd.point.y = points[i].y;
+          sc->path_data = g_array_append_val (sc->path_data, pd);
+          prev = points[i];
+        }
+    }
+
+  /* close the polyline when needed */
+  if (closed)
+    {
+      pd.header.type = CAIRO_PATH_CLOSE_PATH;
+      pd.header.length = 1;
+      sc->path_data = g_array_append_val (sc->path_data, pd);
+    }
+}
+
+/**
+ * gimp_scan_convert_add_polyline:
+ * @sc:     a #GimpScanConvert context
+ * @bezier: a #GimpBezierDesc
+ *
+ * Adds a @bezier path to @sc.
+ *
+ * Please note that you should use gimp_scan_convert_stroke() if you
+ * specify open paths.
+ **/
+void
+gimp_scan_convert_add_bezier (GimpScanConvert       *sc,
+                              const GimpBezierDesc  *bezier)
+{
+  g_return_if_fail (sc != NULL);
+  g_return_if_fail (bezier != NULL);
+
+  sc->path_data = g_array_append_vals (sc->path_data,
+                                       bezier->data, bezier->num_data);
+}
+
+/**
+ * gimp_scan_convert_stroke:
+ * @sc:          a #GimpScanConvert context
+ * @width:       line width in pixels
+ * @join:        how lines should be joined
+ * @cap:         how to render the end of lines
+ * @miter:       convert a mitered join to a bevelled join if the miter would
+ *               extend to a distance of more than @miter times @width from
+ *               the actual join point
+ * @dash_offset: offset to apply on the dash pattern
+ * @dash_info:   dash pattern or %NULL for a solid line
+ *
+ * Stroke the content of a GimpScanConvert. The next
+ * gimp_scan_convert_render() will result in the outline of the
+ * polygon defined with the commands above.
+ *
+ * You cannot add additional polygons after this command.
+ *
+ * Note that if you have nonstandard resolution, "width" gives the
+ * width (in pixels) for a vertical stroke, i.e. use the X resolution
+ * to calculate the width of a stroke when operating with real world
+ * units.
+ */
+void
+gimp_scan_convert_stroke (GimpScanConvert *sc,
+                          gdouble          width,
+                          GimpJoinStyle    join,
+                          GimpCapStyle     cap,
+                          gdouble          miter,
+                          gdouble          dash_offset,
+                          GArray          *dash_info)
+{
+  sc->do_stroke = TRUE;
+  sc->width     = width;
+  sc->join      = join;
+  sc->cap       = cap;
+  sc->miter     = miter;
+
+  if (sc->dash_info)
+    {
+      g_array_free (sc->dash_info, TRUE);
+      sc->dash_info = NULL;
+    }
+
+  if (dash_info && dash_info->len >= 2)
+    {
+      gint          n_dashes;
+      gdouble      *dashes;
+      gint          i;
+
+      dash_offset = dash_offset * MAX (width, 1.0);
+
+      n_dashes = dash_info->len;
+      dashes = g_new (gdouble, dash_info->len);
+
+      for (i = 0; i < dash_info->len ; i++)
+        dashes[i] = MAX (width, 1.0) * g_array_index (dash_info, gdouble, i);
+
+      /* correct 0.0 in the first element (starts with a gap) */
+
+      if (dashes[0] == 0.0)
+        {
+          gdouble first;
+
+          first = dashes[1];
+
+          /* shift the pattern to really starts with a dash and
+           * use the offset to skip into it.
+           */
+          for (i = 0; i < dash_info->len - 2; i++)
+            {
+              dashes[i] = dashes[i+2];
+              dash_offset += dashes[i];
+            }
+
+          if (dash_info->len % 2 == 1)
+            {
+              dashes[dash_info->len - 2] = first;
+              n_dashes --;
+            }
+          else if (dash_info->len > 2)
+           {
+             dashes [dash_info->len - 3] += first;
+             n_dashes -= 2;
+           }
+        }
+
+      /* correct odd number of dash specifiers */
+
+      if (n_dashes % 2 == 1)
+        {
+          gdouble last;
+
+          last = dashes[n_dashes - 1];
+          dashes[0]   += last;
+          dash_offset += last;
+          n_dashes --;
+        }
+
+      if (n_dashes >= 2)
+        {
+          sc->dash_info = g_array_sized_new (FALSE, FALSE,
+                                             sizeof (gdouble), n_dashes);
+          sc->dash_info = g_array_append_vals (sc->dash_info, dashes, n_dashes);
+          sc->dash_offset = dash_offset;
+        }
+
+      g_free (dashes);
+    }
+}
+
+
+/**
+ * gimp_scan_convert_render:
+ * @sc:        a #GimpScanConvert context
+ * @buffer:    the #GeglBuffer to render to
+ * @off_x:     horizontal offset into the @buffer
+ * @off_y:     vertical offset into the @buffer
+ * @antialias: whether to apply antialiasiing
+ *
+ * This is a wrapper around gimp_scan_convert_render_full() that replaces the
+ * content of the @buffer with a rendered form of the path passed in.
+ *
+ * You cannot add additional polygons after this command.
+ */
+void
+gimp_scan_convert_render (GimpScanConvert *sc,
+                          GeglBuffer      *buffer,
+                          gint             off_x,
+                          gint             off_y,
+                          gboolean         antialias)
+{
+  gimp_scan_convert_render_full (sc, buffer, off_x, off_y,
+                                 TRUE, antialias, 1.0);
+}
+
+/**
+ * gimp_scan_convert_render_value:
+ * @sc:     a #GimpScanConvert context
+ * @buffer: the #GeglBuffer to render to
+ * @off_x:  horizontal offset into the @buffer
+ * @off_y:  vertical offset into the @buffer
+ * @value:  value to use for covered pixels
+ *
+ * This is a wrapper around gimp_scan_convert_render_full() that
+ * doesn't do antialiasing but gives control over the value that
+ * should be used for pixels covered by the scan conversion. Uncovered
+ * pixels are set to zero.
+ *
+ * You cannot add additional polygons after this command.
+ */
+void
+gimp_scan_convert_render_value (GimpScanConvert *sc,
+                                GeglBuffer      *buffer,
+                                gint             off_x,
+                                gint             off_y,
+                                gdouble          value)
+{
+  gimp_scan_convert_render_full (sc, buffer, off_x, off_y,
+                                 TRUE, FALSE, value);
+}
+
+/**
+ * gimp_scan_convert_compose:
+ * @sc:     a #GimpScanConvert context
+ * @buffer: the #GeglBuffer to render to
+ * @off_x:  horizontal offset into the @buffer
+ * @off_y:  vertical offset into the @buffer
+ *
+ * This is a wrapper around of gimp_scan_convert_render_full() that composes
+ * the (aliased) scan conversion on top of the content of the @buffer.
+ *
+ * You cannot add additional polygons after this command.
+ */
+void
+gimp_scan_convert_compose (GimpScanConvert *sc,
+                           GeglBuffer      *buffer,
+                           gint             off_x,
+                           gint             off_y)
+{
+  gimp_scan_convert_render_full (sc, buffer, off_x, off_y,
+                                 FALSE, FALSE, 1.0);
+}
+
+/**
+ * gimp_scan_convert_compose_value:
+ * @sc:     a #GimpScanConvert context
+ * @buffer: the #GeglBuffer to render to
+ * @off_x:  horizontal offset into the @buffer
+ * @off_y:  vertical offset into the @buffer
+ * @value:  value to use for covered pixels
+ *
+ * This is a wrapper around gimp_scan_convert_render_full() that
+ * composes the (aliased) scan conversion with value @value on top of the
+ * content of the @buffer.
+ *
+ * You cannot add additional polygons after this command.
+ */
+void
+gimp_scan_convert_compose_value (GimpScanConvert *sc,
+                                 GeglBuffer      *buffer,
+                                 gint             off_x,
+                                 gint             off_y,
+                                 gdouble          value)
+{
+  gimp_scan_convert_render_full (sc, buffer, off_x, off_y,
+                                 FALSE, FALSE, value);
+}
+
+/**
+ * gimp_scan_convert_render_full:
+ * @sc:        a #GimpScanConvert context
+ * @buffer:    the #GeglBuffer to render to
+ * @off_x:     horizontal offset into the @buffer
+ * @off_y:     vertical offset into the @buffer
+ * @replace:   if true the original content of the @buffer gets estroyed
+ * @antialias: if true the rendering happens antialiased
+ * @value:     value to use for covered pixels
+ *
+ * This function renders the area described by the path to the
+ * @buffer, taking the offset @off_x and @off_y in the buffer into
+ * account.  The rendering can happen antialiased and be rendered on
+ * top of existing content or replacing it completely. The @value
+ * specifies the opacity value to be used for the objects in the @sc.
+ *
+ * You cannot add additional polygons after this command.
+ */
+void
+gimp_scan_convert_render_full (GimpScanConvert *sc,
+                               GeglBuffer      *buffer,
+                               gint             off_x,
+                               gint             off_y,
+                               gboolean         replace,
+                               gboolean         antialias,
+                               gdouble          value)
+{
+  const Babl         *format;
+  guchar             *shared_buf      = NULL;
+  gsize               shared_buf_size = 0;
+  GeglBufferIterator *iter;
+  GeglRectangle      *roi;
+  cairo_t            *cr;
+  cairo_surface_t    *surface;
+  cairo_path_t        path;
+  gint                bpp;
+  gint                x, y;
+  gint                width, height;
+
+  g_return_if_fail (sc != NULL);
+  g_return_if_fail (GEGL_IS_BUFFER (buffer));
+
+  x      = gegl_buffer_get_x      (buffer);
+  y      = gegl_buffer_get_y      (buffer);
+  width  = gegl_buffer_get_width  (buffer);
+  height = gegl_buffer_get_height (buffer);
+
+  if (sc->clip && ! gimp_rectangle_intersect (x, y, width, height,
+                                              sc->clip_x, sc->clip_y,
+                                              sc->clip_w, sc->clip_h,
+                                              &x, &y, &width, &height))
+    return;
+
+  path.status   = CAIRO_STATUS_SUCCESS;
+  path.data     = (cairo_path_data_t *) sc->path_data->data;
+  path.num_data = sc->path_data->len;
+
+  format = babl_format ("Y u8");
+  bpp    = babl_format_get_bytes_per_pixel (format);
+
+  iter = gegl_buffer_iterator_new (buffer, NULL, 0, format,
+                                   GEGL_ACCESS_READWRITE, GEGL_ABYSS_NONE, 1);
+  roi = &iter->items[0].roi;
+
+  while (gegl_buffer_iterator_next (iter))
+    {
+      guchar     *data    = iter->items[0].data;
+      guchar     *tmp_buf = NULL;
+      const gint  stride  = cairo_format_stride_for_width (CAIRO_FORMAT_A8,
+                                                           roi->width);
+
+      /*  cairo rowstrides are always multiples of 4, whereas
+       *  maskPR.rowstride can be anything, so to be able to create an
+       *  image surface, we maybe have to create our own temporary
+       *  buffer
+       */
+      if (roi->width * bpp != stride)
+        {
+          if (shared_buf_size < stride * roi->height)
+            {
+              shared_buf_size = stride * roi->height;
+              g_free (shared_buf);
+              shared_buf = g_malloc (shared_buf_size);
+            }
+          tmp_buf = shared_buf;
+
+          if (! replace)
+            {
+              const guchar *src  = data;
+              guchar       *dest = tmp_buf;
+              gint          i;
+
+              for (i = 0; i < roi->height; i++)
+                {
+                  memcpy (dest, src, roi->width * bpp);
+
+                  src  += roi->width * bpp;
+                  dest += stride;
+                }
+            }
+        }
+
+      surface = cairo_image_surface_create_for_data (tmp_buf ?
+                                                     tmp_buf : data,
+                                                     CAIRO_FORMAT_A8,
+                                                     roi->width, roi->height,
+                                                     stride);
+
+      cairo_surface_set_device_offset (surface,
+                                       -off_x - roi->x,
+                                       -off_y - roi->y);
+      cr = cairo_create (surface);
+      cairo_set_operator (cr, CAIRO_OPERATOR_SOURCE);
+
+      if (replace)
+        {
+          cairo_set_source_rgba (cr, 0, 0, 0, 0);
+          cairo_paint (cr);
+        }
+
+      cairo_set_source_rgba (cr, 0, 0, 0, value);
+      cairo_append_path (cr, &path);
+
+      cairo_set_antialias (cr, antialias ?
+                           CAIRO_ANTIALIAS_GRAY : CAIRO_ANTIALIAS_NONE);
+      cairo_set_miter_limit (cr, sc->miter);
+
+      if (sc->do_stroke)
+        {
+          cairo_set_line_cap (cr,
+                              sc->cap == GIMP_CAP_BUTT ? CAIRO_LINE_CAP_BUTT :
+                              sc->cap == GIMP_CAP_ROUND ? CAIRO_LINE_CAP_ROUND :
+                              CAIRO_LINE_CAP_SQUARE);
+          cairo_set_line_join (cr,
+                               sc->join == GIMP_JOIN_MITER ? CAIRO_LINE_JOIN_MITER :
+                               sc->join == GIMP_JOIN_ROUND ? CAIRO_LINE_JOIN_ROUND :
+                               CAIRO_LINE_JOIN_BEVEL);
+
+          cairo_set_line_width (cr, sc->width);
+
+          if (sc->dash_info)
+            cairo_set_dash (cr,
+                            (double *) sc->dash_info->data,
+                            sc->dash_info->len,
+                            sc->dash_offset);
+
+          cairo_scale (cr, 1.0, sc->ratio_xy);
+          cairo_stroke (cr);
+        }
+      else
+        {
+          cairo_set_fill_rule (cr, CAIRO_FILL_RULE_EVEN_ODD);
+          cairo_fill (cr);
+        }
+
+      cairo_destroy (cr);
+      cairo_surface_destroy (surface);
+
+      if (tmp_buf)
+        {
+          const guchar *src  = tmp_buf;
+          guchar       *dest = data;
+          gint          i;
+
+          for (i = 0; i < roi->height; i++)
+            {
+              memcpy (dest, src, roi->width * bpp);
+
+              src  += stride;
+              dest += roi->width * bpp;
+            }
+        }
+    }
+
+  g_free (shared_buf);
+}
diff --git a/app/core/gimpscanconvert.h b/app/core/gimpscanconvert.h
new file mode 100644
index 0000000..9df4da1
--- /dev/null
+++ b/app/core/gimpscanconvert.h
@@ -0,0 +1,81 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1999 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_SCAN_CONVERT_H__
+#define __GIMP_SCAN_CONVERT_H__
+
+
+GimpScanConvert *
+          gimp_scan_convert_new               (void);
+
+GimpScanConvert *
+          gimp_scan_convert_new_from_boundary (const GimpBoundSeg *bound_segs,
+                                               gint                n_bound_segs,
+                                               gint                offset_x,
+                                               gint                offset_y);
+
+void      gimp_scan_convert_free               (GimpScanConvert   *sc);
+void      gimp_scan_convert_set_pixel_ratio    (GimpScanConvert   *sc,
+                                                gdouble            ratio_xy);
+void      gimp_scan_convert_set_clip_rectangle (GimpScanConvert   *sc,
+                                                gint               x,
+                                                gint               y,
+                                                gint               width,
+                                                gint               height);
+void      gimp_scan_convert_add_polyline       (GimpScanConvert   *sc,
+                                                guint              n_points,
+                                                const GimpVector2 *points,
+                                                gboolean           closed);
+void      gimp_scan_convert_add_bezier         (GimpScanConvert      *sc,
+                                                const GimpBezierDesc *bezier);
+void      gimp_scan_convert_stroke             (GimpScanConvert   *sc,
+                                                gdouble            width,
+                                                GimpJoinStyle      join,
+                                                GimpCapStyle       cap,
+                                                gdouble            miter,
+                                                gdouble            dash_offset,
+                                                GArray            *dash_info);
+void      gimp_scan_convert_render_full        (GimpScanConvert   *sc,
+                                                GeglBuffer        *buffer,
+                                                gint               off_x,
+                                                gint               off_y,
+                                                gboolean           replace,
+                                                gboolean           antialias,
+                                                gdouble            value);
+
+void      gimp_scan_convert_render             (GimpScanConvert   *sc,
+                                                GeglBuffer        *buffer,
+                                                gint               off_x,
+                                                gint               off_y,
+                                                gboolean           antialias);
+void      gimp_scan_convert_render_value       (GimpScanConvert   *sc,
+                                                GeglBuffer        *buffer,
+                                                gint               off_x,
+                                                gint               off_y,
+                                                gdouble            value);
+void      gimp_scan_convert_compose            (GimpScanConvert   *sc,
+                                                GeglBuffer        *buffer,
+                                                gint               off_x,
+                                                gint               off_y);
+void      gimp_scan_convert_compose_value      (GimpScanConvert   *sc,
+                                                GeglBuffer        *buffer,
+                                                gint               off_x,
+                                                gint               off_y,
+                                                gdouble            value);
+
+
+#endif /* __GIMP_SCAN_CONVERT_H__ */
diff --git a/app/core/gimpselection.c b/app/core/gimpselection.c
new file mode 100644
index 0000000..5f66b98
--- /dev/null
+++ b/app/core/gimpselection.c
@@ -0,0 +1,863 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <cairo.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpcolor/gimpcolor.h"
+
+#include "core-types.h"
+
+#include "gegl/gimp-babl.h"
+#include "gegl/gimp-gegl-apply-operation.h"
+#include "gegl/gimp-gegl-loops.h"
+
+#include "gimp.h"
+#include "gimpcontext.h"
+#include "gimpdrawable-edit.h"
+#include "gimpdrawable-private.h"
+#include "gimperror.h"
+#include "gimpimage.h"
+#include "gimpimage-undo.h"
+#include "gimpimage-undo-push.h"
+#include "gimplayer.h"
+#include "gimplayer-new.h"
+#include "gimplayermask.h"
+#include "gimplayer-floating-selection.h"
+#include "gimppickable.h"
+#include "gimpselection.h"
+
+#include "gimp-intl.h"
+
+
+static gboolean   gimp_selection_is_attached   (GimpItem            *item);
+static GimpItemTree * gimp_selection_get_tree  (GimpItem            *item);
+static void       gimp_selection_translate     (GimpItem            *item,
+                                                gdouble              offset_x,
+                                                gdouble              offset_y,
+                                                gboolean             push_undo);
+static void       gimp_selection_scale         (GimpItem            *item,
+                                                gint                 new_width,
+                                                gint                 new_height,
+                                                gint                 new_offset_x,
+                                                gint                 new_offset_y,
+                                                GimpInterpolationType interp_type,
+                                                GimpProgress        *progress);
+static void       gimp_selection_resize        (GimpItem            *item,
+                                                GimpContext         *context,
+                                                GimpFillType         fill_type,
+                                                gint                 new_width,
+                                                gint                 new_height,
+                                                gint                 offset_x,
+                                                gint                 offset_y);
+static void       gimp_selection_flip          (GimpItem            *item,
+                                                GimpContext         *context,
+                                                GimpOrientationType  flip_type,
+                                                gdouble              axis,
+                                                gboolean             clip_result);
+static void       gimp_selection_rotate        (GimpItem            *item,
+                                                GimpContext         *context,
+                                                GimpRotationType     rotation_type,
+                                                gdouble              center_x,
+                                                gdouble              center_y,
+                                                gboolean             clip_result);
+static gboolean   gimp_selection_fill          (GimpItem            *item,
+                                                GimpDrawable        *drawable,
+                                                GimpFillOptions     *fill_options,
+                                                gboolean             push_undo,
+                                                GimpProgress        *progress,
+                                                GError             **error);
+static gboolean   gimp_selection_stroke        (GimpItem            *item,
+                                                GimpDrawable        *drawable,
+                                                GimpStrokeOptions   *stroke_options,
+                                                gboolean             push_undo,
+                                                GimpProgress        *progress,
+                                                GError             **error);
+static void       gimp_selection_convert_type  (GimpDrawable        *drawable,
+                                                GimpImage           *dest_image,
+                                                const Babl          *new_format,
+                                                GimpColorProfile    *dest_profile,
+                                                GeglDitherMethod     layer_dither_type,
+                                                GeglDitherMethod     mask_dither_type,
+                                                gboolean             push_undo,
+                                                GimpProgress        *progress);
+static void gimp_selection_invalidate_boundary (GimpDrawable        *drawable);
+
+static gboolean   gimp_selection_boundary      (GimpChannel         *channel,
+                                                const GimpBoundSeg **segs_in,
+                                                const GimpBoundSeg **segs_out,
+                                                gint                *num_segs_in,
+                                                gint                *num_segs_out,
+                                                gint                 x1,
+                                                gint                 y1,
+                                                gint                 x2,
+                                                gint                 y2);
+static gboolean   gimp_selection_is_empty      (GimpChannel         *channel);
+static void       gimp_selection_feather       (GimpChannel         *channel,
+                                                gdouble              radius_x,
+                                                gdouble              radius_y,
+                                                gboolean             edge_lock,
+                                                gboolean             push_undo);
+static void       gimp_selection_sharpen       (GimpChannel         *channel,
+                                                gboolean             push_undo);
+static void       gimp_selection_clear         (GimpChannel         *channel,
+                                                const gchar         *undo_desc,
+                                                gboolean             push_undo);
+static void       gimp_selection_all           (GimpChannel         *channel,
+                                                gboolean             push_undo);
+static void       gimp_selection_invert        (GimpChannel         *channel,
+                                                gboolean             push_undo);
+static void       gimp_selection_border        (GimpChannel         *channel,
+                                                gint                 radius_x,
+                                                gint                 radius_y,
+                                                GimpChannelBorderStyle style,
+                                                gboolean             edge_lock,
+                                                gboolean             push_undo);
+static void       gimp_selection_grow          (GimpChannel         *channel,
+                                                gint                 radius_x,
+                                                gint                 radius_y,
+                                                gboolean             push_undo);
+static void       gimp_selection_shrink        (GimpChannel         *channel,
+                                                gint                 radius_x,
+                                                gint                 radius_y,
+                                                gboolean             edge_lock,
+                                                gboolean             push_undo);
+static void       gimp_selection_flood         (GimpChannel         *channel,
+                                                gboolean             push_undo);
+
+
+G_DEFINE_TYPE (GimpSelection, gimp_selection, GIMP_TYPE_CHANNEL)
+
+#define parent_class gimp_selection_parent_class
+
+
+static void
+gimp_selection_class_init (GimpSelectionClass *klass)
+{
+  GimpViewableClass *viewable_class = GIMP_VIEWABLE_CLASS (klass);
+  GimpItemClass     *item_class     = GIMP_ITEM_CLASS (klass);
+  GimpDrawableClass *drawable_class = GIMP_DRAWABLE_CLASS (klass);
+  GimpChannelClass  *channel_class  = GIMP_CHANNEL_CLASS (klass);
+
+  viewable_class->default_icon_name   = "gimp-selection";
+
+  item_class->is_attached             = gimp_selection_is_attached;
+  item_class->get_tree                = gimp_selection_get_tree;
+  item_class->translate               = gimp_selection_translate;
+  item_class->scale                   = gimp_selection_scale;
+  item_class->resize                  = gimp_selection_resize;
+  item_class->flip                    = gimp_selection_flip;
+  item_class->rotate                  = gimp_selection_rotate;
+  item_class->fill                    = gimp_selection_fill;
+  item_class->stroke                  = gimp_selection_stroke;
+  item_class->default_name            = _("Selection Mask");
+  item_class->translate_desc          = C_("undo-type", "Move Selection");
+  item_class->fill_desc               = C_("undo-type", "Fill Selection");
+  item_class->stroke_desc             = C_("undo-type", "Stroke Selection");
+
+  drawable_class->convert_type        = gimp_selection_convert_type;
+  drawable_class->invalidate_boundary = gimp_selection_invalidate_boundary;
+
+  channel_class->boundary             = gimp_selection_boundary;
+  channel_class->is_empty             = gimp_selection_is_empty;
+  channel_class->feather              = gimp_selection_feather;
+  channel_class->sharpen              = gimp_selection_sharpen;
+  channel_class->clear                = gimp_selection_clear;
+  channel_class->all                  = gimp_selection_all;
+  channel_class->invert               = gimp_selection_invert;
+  channel_class->border               = gimp_selection_border;
+  channel_class->grow                 = gimp_selection_grow;
+  channel_class->shrink               = gimp_selection_shrink;
+  channel_class->flood                = gimp_selection_flood;
+
+  channel_class->feather_desc         = C_("undo-type", "Feather Selection");
+  channel_class->sharpen_desc         = C_("undo-type", "Sharpen Selection");
+  channel_class->clear_desc           = C_("undo-type", "Select None");
+  channel_class->all_desc             = C_("undo-type", "Select All");
+  channel_class->invert_desc          = C_("undo-type", "Invert Selection");
+  channel_class->border_desc          = C_("undo-type", "Border Selection");
+  channel_class->grow_desc            = C_("undo-type", "Grow Selection");
+  channel_class->shrink_desc          = C_("undo-type", "Shrink Selection");
+  channel_class->flood_desc           = C_("undo-type", "Remove Holes");
+}
+
+static void
+gimp_selection_init (GimpSelection *selection)
+{
+}
+
+static gboolean
+gimp_selection_is_attached (GimpItem *item)
+{
+  return (GIMP_IS_IMAGE (gimp_item_get_image (item)) &&
+          gimp_image_get_mask (gimp_item_get_image (item)) ==
+          GIMP_CHANNEL (item));
+}
+
+static GimpItemTree *
+gimp_selection_get_tree (GimpItem *item)
+{
+  return NULL;
+}
+
+static void
+gimp_selection_translate (GimpItem *item,
+                          gdouble   offset_x,
+                          gdouble   offset_y,
+                          gboolean  push_undo)
+{
+  GIMP_ITEM_CLASS (parent_class)->translate (item, offset_x, offset_y,
+                                             push_undo);
+}
+
+static void
+gimp_selection_scale (GimpItem              *item,
+                      gint                   new_width,
+                      gint                   new_height,
+                      gint                   new_offset_x,
+                      gint                   new_offset_y,
+                      GimpInterpolationType  interp_type,
+                      GimpProgress          *progress)
+{
+  GIMP_ITEM_CLASS (parent_class)->scale (item, new_width, new_height,
+                                         new_offset_x, new_offset_y,
+                                         interp_type, progress);
+
+  gimp_item_set_offset (item, 0, 0);
+}
+
+static void
+gimp_selection_resize (GimpItem     *item,
+                       GimpContext  *context,
+                       GimpFillType  fill_type,
+                       gint          new_width,
+                       gint          new_height,
+                       gint          offset_x,
+                       gint          offset_y)
+{
+  GIMP_ITEM_CLASS (parent_class)->resize (item, context, GIMP_FILL_TRANSPARENT,
+                                          new_width, new_height,
+                                          offset_x, offset_y);
+
+  gimp_item_set_offset (item, 0, 0);
+}
+
+static void
+gimp_selection_flip (GimpItem            *item,
+                     GimpContext         *context,
+                     GimpOrientationType  flip_type,
+                     gdouble              axis,
+                     gboolean             clip_result)
+{
+  GIMP_ITEM_CLASS (parent_class)->flip (item, context, flip_type, axis, TRUE);
+}
+
+static void
+gimp_selection_rotate (GimpItem         *item,
+                       GimpContext      *context,
+                       GimpRotationType  rotation_type,
+                       gdouble           center_x,
+                       gdouble           center_y,
+                       gboolean          clip_result)
+{
+  GIMP_ITEM_CLASS (parent_class)->rotate (item, context, rotation_type,
+                                          center_x, center_y,
+                                          clip_result);
+}
+
+static gboolean
+gimp_selection_fill (GimpItem         *item,
+                     GimpDrawable     *drawable,
+                     GimpFillOptions  *fill_options,
+                     gboolean          push_undo,
+                     GimpProgress     *progress,
+                     GError          **error)
+{
+  GimpSelection      *selection = GIMP_SELECTION (item);
+  const GimpBoundSeg *dummy_in;
+  const GimpBoundSeg *dummy_out;
+  gint                num_dummy_in;
+  gint                num_dummy_out;
+  gboolean            retval;
+
+  if (! gimp_channel_boundary (GIMP_CHANNEL (selection),
+                               &dummy_in, &dummy_out,
+                               &num_dummy_in, &num_dummy_out,
+                               0, 0, 0, 0))
+    {
+      g_set_error_literal (error, GIMP_ERROR, GIMP_FAILED,
+                           _("There is no selection to fill."));
+      return FALSE;
+    }
+
+  gimp_selection_suspend (selection);
+
+  retval = GIMP_ITEM_CLASS (parent_class)->fill (item, drawable,
+                                                 fill_options,
+                                                 push_undo, progress, error);
+
+  gimp_selection_resume (selection);
+
+  return retval;
+}
+
+static gboolean
+gimp_selection_stroke (GimpItem           *item,
+                       GimpDrawable       *drawable,
+                       GimpStrokeOptions  *stroke_options,
+                       gboolean            push_undo,
+                       GimpProgress       *progress,
+                       GError            **error)
+{
+  GimpSelection      *selection = GIMP_SELECTION (item);
+  const GimpBoundSeg *dummy_in;
+  const GimpBoundSeg *dummy_out;
+  gint                num_dummy_in;
+  gint                num_dummy_out;
+  gboolean            retval;
+
+  if (! gimp_channel_boundary (GIMP_CHANNEL (selection),
+                               &dummy_in, &dummy_out,
+                               &num_dummy_in, &num_dummy_out,
+                               0, 0, 0, 0))
+    {
+      g_set_error_literal (error, GIMP_ERROR, GIMP_FAILED,
+                           _("There is no selection to stroke."));
+      return FALSE;
+    }
+
+  gimp_selection_suspend (selection);
+
+  retval = GIMP_ITEM_CLASS (parent_class)->stroke (item, drawable,
+                                                   stroke_options,
+                                                   push_undo, progress, error);
+
+  gimp_selection_resume (selection);
+
+  return retval;
+}
+
+static void
+gimp_selection_convert_type (GimpDrawable      *drawable,
+                             GimpImage         *dest_image,
+                             const Babl        *new_format,
+                             GimpColorProfile  *dest_profile,
+                             GeglDitherMethod   layer_dither_type,
+                             GeglDitherMethod   mask_dither_type,
+                             gboolean           push_undo,
+                             GimpProgress      *progress)
+{
+  new_format =
+    gimp_babl_mask_format (gimp_babl_format_get_precision (new_format));
+
+  GIMP_DRAWABLE_CLASS (parent_class)->convert_type (drawable, dest_image,
+                                                    new_format,
+                                                    dest_profile,
+                                                    layer_dither_type,
+                                                    mask_dither_type,
+                                                    push_undo,
+                                                    progress);
+}
+
+static void
+gimp_selection_invalidate_boundary (GimpDrawable *drawable)
+{
+  GimpImage *image = gimp_item_get_image (GIMP_ITEM (drawable));
+  GimpLayer *layer;
+
+  /*  Turn the current selection off  */
+  gimp_image_selection_invalidate (image);
+
+  GIMP_DRAWABLE_CLASS (parent_class)->invalidate_boundary (drawable);
+
+  /*  If there is a floating selection, update it's area...
+   *  we need to do this since this selection mask can act as an additional
+   *  mask in the composition of the floating selection
+   */
+  layer = gimp_image_get_active_layer (image);
+
+  if (layer && gimp_layer_is_floating_sel (layer))
+    {
+      gimp_drawable_update (GIMP_DRAWABLE (layer), 0, 0, -1, -1);
+    }
+
+#if 0
+  /*  invalidate the preview  */
+  drawable->private->preview_valid = FALSE;
+#endif
+}
+
+static gboolean
+gimp_selection_boundary (GimpChannel         *channel,
+                         const GimpBoundSeg **segs_in,
+                         const GimpBoundSeg **segs_out,
+                         gint                *num_segs_in,
+                         gint                *num_segs_out,
+                         gint                 unused1,
+                         gint                 unused2,
+                         gint                 unused3,
+                         gint                 unused4)
+{
+  GimpImage    *image = gimp_item_get_image (GIMP_ITEM (channel));
+  GimpDrawable *drawable;
+  GimpLayer    *layer;
+
+  if ((layer = gimp_image_get_floating_selection (image)))
+    {
+      /*  If there is a floating selection, then
+       *  we need to do some slightly different boundaries.
+       *  Instead of inside and outside boundaries being defined
+       *  by the extents of the layer, the inside boundary (the one
+       *  that actually marches and is black/white) is the boundary of
+       *  the floating selection.  The outside boundary (doesn't move,
+       *  is black/gray) is defined as the normal selection mask
+       */
+
+      /*  Find the selection mask boundary  */
+      GIMP_CHANNEL_CLASS (parent_class)->boundary (channel,
+                                                   segs_in, segs_out,
+                                                   num_segs_in, num_segs_out,
+                                                   0, 0, 0, 0);
+
+      /*  Find the floating selection boundary  */
+      *segs_in = floating_sel_boundary (layer, num_segs_in);
+
+      return TRUE;
+    }
+  else if ((drawable = gimp_image_get_active_drawable (image)) &&
+           GIMP_IS_CHANNEL (drawable))
+    {
+      /*  Otherwise, return the boundary...if a channel is active  */
+
+      return GIMP_CHANNEL_CLASS (parent_class)->boundary (channel,
+                                                          segs_in, segs_out,
+                                                          num_segs_in,
+                                                          num_segs_out,
+                                                          0, 0,
+                                                          gimp_image_get_width  (image),
+                                                          gimp_image_get_height (image));
+    }
+  else if ((layer = gimp_image_get_active_layer (image)))
+    {
+      /*  If a layer is active, we return multiple boundaries based
+       *  on the extents
+       */
+
+      gint x1, y1;
+      gint x2, y2;
+      gint offset_x;
+      gint offset_y;
+
+      gimp_item_get_offset (GIMP_ITEM (layer), &offset_x, &offset_y);
+
+      x1 = CLAMP (offset_x, 0, gimp_image_get_width  (image));
+      y1 = CLAMP (offset_y, 0, gimp_image_get_height (image));
+      x2 = CLAMP (offset_x + gimp_item_get_width (GIMP_ITEM (layer)),
+                  0, gimp_image_get_width (image));
+      y2 = CLAMP (offset_y + gimp_item_get_height (GIMP_ITEM (layer)),
+                  0, gimp_image_get_height (image));
+
+      return GIMP_CHANNEL_CLASS (parent_class)->boundary (channel,
+                                                          segs_in, segs_out,
+                                                          num_segs_in,
+                                                          num_segs_out,
+                                                          x1, y1, x2, y2);
+    }
+
+  *segs_in      = NULL;
+  *segs_out     = NULL;
+  *num_segs_in  = 0;
+  *num_segs_out = 0;
+
+  return FALSE;
+}
+
+static gboolean
+gimp_selection_is_empty (GimpChannel *channel)
+{
+  GimpSelection *selection = GIMP_SELECTION (channel);
+
+  /*  in order to allow stroking of selections, we need to pretend here
+   *  that the selection mask is empty so that it doesn't mask the paint
+   *  during the stroke operation.
+   */
+  if (selection->suspend_count > 0)
+    return TRUE;
+
+  return GIMP_CHANNEL_CLASS (parent_class)->is_empty (channel);
+}
+
+static void
+gimp_selection_feather (GimpChannel *channel,
+                        gdouble      radius_x,
+                        gdouble      radius_y,
+                        gboolean     edge_lock,
+                        gboolean     push_undo)
+{
+  GIMP_CHANNEL_CLASS (parent_class)->feather (channel, radius_x, radius_y,
+                                              edge_lock, push_undo);
+}
+
+static void
+gimp_selection_sharpen (GimpChannel *channel,
+                        gboolean     push_undo)
+{
+  GIMP_CHANNEL_CLASS (parent_class)->sharpen (channel, push_undo);
+}
+
+static void
+gimp_selection_clear (GimpChannel *channel,
+                      const gchar *undo_desc,
+                      gboolean     push_undo)
+{
+  GIMP_CHANNEL_CLASS (parent_class)->clear (channel, undo_desc, push_undo);
+}
+
+static void
+gimp_selection_all (GimpChannel *channel,
+                    gboolean     push_undo)
+{
+  GIMP_CHANNEL_CLASS (parent_class)->all (channel, push_undo);
+}
+
+static void
+gimp_selection_invert (GimpChannel *channel,
+                       gboolean     push_undo)
+{
+  GIMP_CHANNEL_CLASS (parent_class)->invert (channel, push_undo);
+}
+
+static void
+gimp_selection_border (GimpChannel            *channel,
+                       gint                    radius_x,
+                       gint                    radius_y,
+                       GimpChannelBorderStyle  style,
+                       gboolean                edge_lock,
+                       gboolean                push_undo)
+{
+  GIMP_CHANNEL_CLASS (parent_class)->border (channel,
+                                             radius_x, radius_y,
+                                             style, edge_lock,
+                                             push_undo);
+}
+
+static void
+gimp_selection_grow (GimpChannel *channel,
+                     gint         radius_x,
+                     gint         radius_y,
+                     gboolean     push_undo)
+{
+  GIMP_CHANNEL_CLASS (parent_class)->grow (channel,
+                                           radius_x, radius_y,
+                                           push_undo);
+}
+
+static void
+gimp_selection_shrink (GimpChannel *channel,
+                       gint         radius_x,
+                       gint         radius_y,
+                       gboolean     edge_lock,
+                       gboolean     push_undo)
+{
+  GIMP_CHANNEL_CLASS (parent_class)->shrink (channel,
+                                             radius_x, radius_y, edge_lock,
+                                             push_undo);
+}
+
+static void
+gimp_selection_flood (GimpChannel *channel,
+                      gboolean     push_undo)
+{
+  GIMP_CHANNEL_CLASS (parent_class)->flood (channel, push_undo);
+}
+
+
+/*  public functions  */
+
+GimpChannel *
+gimp_selection_new (GimpImage *image,
+                    gint       width,
+                    gint       height)
+{
+  GimpRGB      black = { 0.0, 0.0, 0.0, 0.5 };
+  GimpChannel *channel;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (width > 0 && height > 0, NULL);
+
+  channel = GIMP_CHANNEL (gimp_drawable_new (GIMP_TYPE_SELECTION,
+                                             image, NULL,
+                                             0, 0, width, height,
+                                             gimp_image_get_mask_format (image)));
+
+  gimp_channel_set_color (channel, &black, FALSE);
+  gimp_channel_set_show_masked (channel, TRUE);
+
+  channel->x2 = width;
+  channel->y2 = height;
+
+  return channel;
+}
+
+gint
+gimp_selection_suspend (GimpSelection *selection)
+{
+  g_return_val_if_fail (GIMP_IS_SELECTION (selection), 0);
+
+  selection->suspend_count++;
+
+  return selection->suspend_count;
+}
+
+gint
+gimp_selection_resume (GimpSelection *selection)
+{
+  g_return_val_if_fail (GIMP_IS_SELECTION (selection), 0);
+  g_return_val_if_fail (selection->suspend_count > 0, 0);
+
+  selection->suspend_count--;
+
+  return selection->suspend_count;
+}
+
+GeglBuffer *
+gimp_selection_extract (GimpSelection *selection,
+                        GimpPickable  *pickable,
+                        GimpContext   *context,
+                        gboolean       cut_image,
+                        gboolean       keep_indexed,
+                        gboolean       add_alpha,
+                        gint          *offset_x,
+                        gint          *offset_y,
+                        GError       **error)
+{
+  GimpImage  *image;
+  GeglBuffer *src_buffer;
+  GeglBuffer *dest_buffer;
+  const Babl *src_format;
+  const Babl *dest_format;
+  gint        x1, y1, x2, y2;
+  gboolean    non_empty;
+  gint        off_x, off_y;
+
+  g_return_val_if_fail (GIMP_IS_SELECTION (selection), NULL);
+  g_return_val_if_fail (GIMP_IS_PICKABLE (pickable), NULL);
+  if (GIMP_IS_ITEM (pickable))
+    g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (pickable)), NULL);
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, NULL);
+
+  image = gimp_pickable_get_image (pickable);
+
+  /*  If there are no bounds, then just extract the entire image
+   *  This may not be the correct behavior, but after getting rid
+   *  of floating selections, it's still tempting to "cut" or "copy"
+   *  a small layer and expect it to work, even though there is no
+   *  actual selection mask
+   */
+  if (GIMP_IS_DRAWABLE (pickable))
+    {
+      non_empty = gimp_item_mask_bounds (GIMP_ITEM (pickable),
+                                         &x1, &y1, &x2, &y2);
+
+      gimp_item_get_offset (GIMP_ITEM (pickable), &off_x, &off_y);
+    }
+  else
+    {
+      non_empty = gimp_item_bounds (GIMP_ITEM (selection),
+                                    &x1, &y1, &x2, &y2);
+      x2 += x1;
+      y2 += y1;
+
+      off_x = 0;
+      off_y = 0;
+
+      /* can't cut from non-drawables, fall back to copy */
+      cut_image = FALSE;
+    }
+
+  if (non_empty && ((x1 == x2) || (y1 == y2)))
+    {
+      g_set_error_literal (error, GIMP_ERROR, GIMP_FAILED,
+                           _("Unable to cut or copy because the "
+                             "selected region is empty."));
+      return NULL;
+    }
+
+  /*  If there is a selection, we must add alpha because the selection
+   *  could have any shape.
+   */
+  if (non_empty)
+    add_alpha = TRUE;
+
+  src_format = gimp_pickable_get_format (pickable);
+
+  /*  How many bytes in the temp buffer?  */
+  if (babl_format_is_palette (src_format) && ! keep_indexed)
+    {
+      dest_format = gimp_image_get_format (image, GIMP_RGB,
+                                           gimp_image_get_precision (image),
+                                           add_alpha ||
+                                           babl_format_has_alpha (src_format));
+    }
+  else
+    {
+      if (add_alpha)
+        dest_format = gimp_pickable_get_format_with_alpha (pickable);
+      else
+        dest_format = src_format;
+    }
+
+  gimp_pickable_flush (pickable);
+
+  src_buffer = gimp_pickable_get_buffer (pickable);
+
+  /*  Allocate the temp buffer  */
+  dest_buffer = gegl_buffer_new (GEGL_RECTANGLE (0, 0, x2 - x1, y2 - y1),
+                                 dest_format);
+
+  /*  First, copy the pixels, possibly doing INDEXED->RGB and adding alpha  */
+  gimp_gegl_buffer_copy (src_buffer,  GEGL_RECTANGLE (x1, y1, x2 - x1, y2 - y1),
+                         GEGL_ABYSS_NONE,
+                         dest_buffer, GEGL_RECTANGLE (0, 0, 0, 0));
+
+  if (non_empty)
+    {
+      /*  If there is a selection, mask the dest_buffer with it  */
+
+      GeglBuffer *mask_buffer;
+
+      mask_buffer = gimp_drawable_get_buffer (GIMP_DRAWABLE (selection));
+
+      gimp_gegl_apply_opacity (dest_buffer, NULL, NULL, dest_buffer,
+                               mask_buffer,
+                               - (off_x + x1),
+                               - (off_y + y1),
+                               1.0);
+
+      if (cut_image)
+        {
+          gimp_drawable_edit_clear (GIMP_DRAWABLE (pickable), context);
+        }
+    }
+  else if (cut_image)
+    {
+      /*  If we're cutting without selection, remove either the layer
+       *  (or floating selection), the layer mask, or the channel
+       */
+      if (GIMP_IS_LAYER (pickable))
+        {
+          gimp_image_remove_layer (image, GIMP_LAYER (pickable),
+                                   TRUE, NULL);
+        }
+      else if (GIMP_IS_LAYER_MASK (pickable))
+        {
+          gimp_layer_apply_mask (gimp_layer_mask_get_layer (GIMP_LAYER_MASK (pickable)),
+                                 GIMP_MASK_DISCARD, TRUE);
+        }
+      else if (GIMP_IS_CHANNEL (pickable))
+        {
+          gimp_image_remove_channel (image, GIMP_CHANNEL (pickable),
+                                     TRUE, NULL);
+        }
+    }
+
+  *offset_x = x1 + off_x;
+  *offset_y = y1 + off_y;
+
+  return dest_buffer;
+}
+
+GimpLayer *
+gimp_selection_float (GimpSelection *selection,
+                      GimpDrawable  *drawable,
+                      GimpContext   *context,
+                      gboolean       cut_image,
+                      gint           off_x,
+                      gint           off_y,
+                      GError       **error)
+{
+  GimpImage        *image;
+  GimpLayer        *layer;
+  GeglBuffer       *buffer;
+  GimpColorProfile *profile;
+  gint              x1, y1;
+  gint              x2, y2;
+
+  g_return_val_if_fail (GIMP_IS_SELECTION (selection), NULL);
+  g_return_val_if_fail (GIMP_IS_DRAWABLE (drawable), NULL);
+  g_return_val_if_fail (gimp_item_is_attached (GIMP_ITEM (drawable)), NULL);
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, NULL);
+
+  image = gimp_item_get_image (GIMP_ITEM (selection));
+
+  /*  Make sure there is a region to float...  */
+  if (! gimp_item_mask_bounds (GIMP_ITEM (drawable), &x1, &y1, &x2, &y2) ||
+      (x1 == x2 || y1 == y2))
+    {
+      g_set_error_literal (error, GIMP_ERROR, GIMP_FAILED,
+                           _("Cannot float selection because the selected "
+                             "region is empty."));
+      return NULL;
+    }
+
+  /*  Start an undo group  */
+  gimp_image_undo_group_start (image, GIMP_UNDO_GROUP_FS_FLOAT,
+                               C_("undo-type", "Float Selection"));
+
+  /*  Cut or copy the selected region  */
+  buffer = gimp_selection_extract (selection, GIMP_PICKABLE (drawable), context,
+                                   cut_image, FALSE, TRUE,
+                                   &x1, &y1, NULL);
+
+  profile = gimp_color_managed_get_color_profile (GIMP_COLOR_MANAGED (drawable));
+
+  /*  Clear the selection  */
+  gimp_channel_clear (GIMP_CHANNEL (selection), NULL, TRUE);
+
+  /* Create a new layer from the buffer, using the drawable's type
+   *  because it may be different from the image's type if we cut from
+   *  a channel or layer mask
+   */
+  layer = gimp_layer_new_from_gegl_buffer (buffer, image,
+                                           gimp_drawable_get_format_with_alpha (drawable),
+                                           _("Floated Layer"),
+                                           GIMP_OPACITY_OPAQUE,
+                                           gimp_image_get_default_new_layer_mode (image),
+                                           profile);
+
+  /*  Set the offsets  */
+  gimp_item_set_offset (GIMP_ITEM (layer), x1 + off_x, y1 + off_y);
+
+  /*  Free the temp buffer  */
+  g_object_unref (buffer);
+
+  /*  Add the floating layer to the image  */
+  floating_sel_attach (layer, drawable);
+
+  /*  End an undo group  */
+  gimp_image_undo_group_end (image);
+
+  /*  invalidate the image's boundary variables  */
+  GIMP_CHANNEL (selection)->boundary_known = FALSE;
+
+  return layer;
+}
diff --git a/app/core/gimpselection.h b/app/core/gimpselection.h
new file mode 100644
index 0000000..64a2962
--- /dev/null
+++ b/app/core/gimpselection.h
@@ -0,0 +1,76 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_SELECTION_H__
+#define __GIMP_SELECTION_H__
+
+
+#include "gimpchannel.h"
+
+
+#define GIMP_TYPE_SELECTION            (gimp_selection_get_type ())
+#define GIMP_SELECTION(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_SELECTION, GimpSelection))
+#define GIMP_SELECTION_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_SELECTION, GimpSelectionClass))
+#define GIMP_IS_SELECTION(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_SELECTION))
+#define GIMP_IS_SELECTION_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_SELECTION))
+#define GIMP_SELECTION_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_SELECTION, GimpSelectionClass))
+
+
+typedef struct _GimpSelectionClass GimpSelectionClass;
+
+struct _GimpSelection
+{
+  GimpChannel parent_instance;
+
+  gint        suspend_count;
+};
+
+struct _GimpSelectionClass
+{
+  GimpChannelClass parent_class;
+};
+
+
+GType         gimp_selection_get_type (void) G_GNUC_CONST;
+
+GimpChannel * gimp_selection_new      (GimpImage     *image,
+                                       gint           width,
+                                       gint           height);
+
+gint          gimp_selection_suspend  (GimpSelection *selection);
+gint          gimp_selection_resume   (GimpSelection *selection);
+
+GeglBuffer  * gimp_selection_extract  (GimpSelection *selection,
+                                       GimpPickable  *pickable,
+                                       GimpContext   *context,
+                                       gboolean       cut_image,
+                                       gboolean       keep_indexed,
+                                       gboolean       add_alpha,
+                                       gint          *offset_x,
+                                       gint          *offset_y,
+                                       GError       **error);
+
+GimpLayer   * gimp_selection_float    (GimpSelection *selection,
+                                       GimpDrawable  *drawable,
+                                       GimpContext   *context,
+                                       gboolean       cut_image,
+                                       gint           off_x,
+                                       gint           off_y,
+                                       GError       **error);
+
+
+#endif /* __GIMP_SELECTION_H__ */
diff --git a/app/core/gimpsettings.c b/app/core/gimpsettings.c
new file mode 100644
index 0000000..ee21a36
--- /dev/null
+++ b/app/core/gimpsettings.c
@@ -0,0 +1,195 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpsettings.c
+ * Copyright (C) 2008 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpconfig/gimpconfig.h"
+
+#include "core-types.h"
+
+#include "gimpsettings.h"
+
+#include "gimp-intl.h"
+
+
+enum
+{
+  PROP_0,
+  PROP_TIME
+};
+
+
+static void    gimp_settings_get_property    (GObject       *object,
+                                              guint          property_id,
+                                              GValue        *value,
+                                              GParamSpec    *pspec);
+static void    gimp_settings_set_property    (GObject       *object,
+                                              guint          property_id,
+                                              const GValue  *value,
+                                              GParamSpec    *pspec);
+
+static gchar * gimp_settings_get_description (GimpViewable  *viewable,
+                                              gchar        **tooltip);
+
+
+G_DEFINE_TYPE (GimpSettings, gimp_settings, GIMP_TYPE_VIEWABLE)
+
+#define parent_class gimp_settings_parent_class
+
+
+static void
+gimp_settings_class_init (GimpSettingsClass *klass)
+{
+  GObjectClass      *object_class   = G_OBJECT_CLASS (klass);
+  GimpViewableClass *viewable_class = GIMP_VIEWABLE_CLASS (klass);
+
+  object_class->set_property      = gimp_settings_set_property;
+  object_class->get_property      = gimp_settings_get_property;
+
+  viewable_class->get_description = gimp_settings_get_description;
+  viewable_class->name_editable   = TRUE;
+
+  GIMP_CONFIG_PROP_INT64 (object_class, PROP_TIME,
+                          "time",
+                          "Time",
+                          "Time of settings creation",
+                          0, G_MAXINT64, 0, 0);
+}
+
+static void
+gimp_settings_init (GimpSettings *settings)
+{
+}
+
+static void
+gimp_settings_get_property (GObject    *object,
+                            guint       property_id,
+                            GValue     *value,
+                            GParamSpec *pspec)
+{
+  GimpSettings *settings = GIMP_SETTINGS (object);
+
+  switch (property_id)
+    {
+    case PROP_TIME:
+      g_value_set_int64 (value, settings->time);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_settings_set_property (GObject      *object,
+                            guint         property_id,
+                            const GValue *value,
+                            GParamSpec   *pspec)
+{
+  GimpSettings *settings = GIMP_SETTINGS (object);
+
+  switch (property_id)
+    {
+    case PROP_TIME:
+      settings->time = g_value_get_int64 (value);
+
+      if (settings->time > 0)
+        {
+          GDateTime *utc   = g_date_time_new_from_unix_utc (settings->time);
+          GDateTime *local = g_date_time_to_local (utc);
+          gchar     *name;
+
+          name = g_date_time_format (local, "%Y-%m-%d %H:%M:%S");
+          gimp_object_take_name (GIMP_OBJECT (settings), name);
+
+          g_date_time_unref (local);
+          g_date_time_unref (utc);
+        }
+      break;
+
+   default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static gchar *
+gimp_settings_get_description (GimpViewable  *viewable,
+                               gchar        **tooltip)
+{
+  GimpSettings *settings = GIMP_SETTINGS (viewable);
+
+  if (settings->time > 0)
+    {
+      if (tooltip)
+        *tooltip = g_strdup ("You can rename automatic presets "
+                             "to make them permanently saved");
+
+      return g_strdup_printf (_("Last used: %s"),
+                              gimp_object_get_name (settings));
+    }
+
+  return GIMP_VIEWABLE_CLASS (parent_class)->get_description (viewable,
+                                                              tooltip);
+}
+
+
+/*  public functions  */
+
+gint
+gimp_settings_compare (GimpSettings *a,
+                       GimpSettings *b)
+{
+  const gchar *name_a = gimp_object_get_name (a);
+  const gchar *name_b = gimp_object_get_name (b);
+
+  if (a->time > 0 && b->time > 0)
+    {
+      return - strcmp (name_a, name_b);
+    }
+  else if (a->time > 0)
+    {
+      return -1;
+    }
+  else if (b->time > 0)
+    {
+      return 1;
+    }
+  else if (name_a && name_b)
+    {
+      return strcmp (name_a, name_b);
+    }
+  else if (name_a)
+    {
+      return 1;
+    }
+  else if (name_b)
+    {
+      return -1;
+    }
+
+  return 0;
+}
diff --git a/app/core/gimpsettings.h b/app/core/gimpsettings.h
new file mode 100644
index 0000000..73aa96f
--- /dev/null
+++ b/app/core/gimpsettings.h
@@ -0,0 +1,57 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpsettings.h
+ * Copyright (C) 2008 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_SETTINGS_H__
+#define __GIMP_SETTINGS_H__
+
+
+#include "gimpviewable.h"
+
+
+#define GIMP_TYPE_SETTINGS            (gimp_settings_get_type ())
+#define GIMP_SETTINGS(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_SETTINGS, GimpSettings))
+#define GIMP_SETTINGS_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass),  GIMP_TYPE_SETTINGS, GimpSettingsClass))
+#define GIMP_IS_SETTINGS(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_SETTINGS))
+#define GIMP_IS_SETTINGS_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass),  GIMP_TYPE_SETTINGS))
+#define GIMP_SETTINGS_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj),  GIMP_TYPE_SETTINGS, GimpSettingsClass))
+
+
+typedef struct _GimpSettingsClass GimpSettingsClass;
+
+struct _GimpSettings
+{
+  GimpViewable  parent_instance;
+
+  gint64        time;
+};
+
+struct _GimpSettingsClass
+{
+  GimpViewableClass  parent_class;
+};
+
+
+GType   gimp_settings_get_type (void) G_GNUC_CONST;
+
+gint    gimp_settings_compare  (GimpSettings *a,
+                                GimpSettings *b);
+
+
+#endif /* __GIMP_SETTINGS_H__ */
diff --git a/app/core/gimpstrokeoptions.c b/app/core/gimpstrokeoptions.c
new file mode 100644
index 0000000..3bb5c92
--- /dev/null
+++ b/app/core/gimpstrokeoptions.c
@@ -0,0 +1,638 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1999 Spencer Kimball and Peter Mattis
+ *
+ * gimpstrokeoptions.c
+ * Copyright (C) 2003 Simon Budig
+ * Copyright (C) 2004 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpconfig/gimpconfig.h"
+
+#include "core-types.h"
+
+#include "config/gimpcoreconfig.h"
+
+#include "gimp.h"
+#include "gimpcontext.h"
+#include "gimpdashpattern.h"
+#include "gimpmarshal.h"
+#include "gimppaintinfo.h"
+#include "gimpparamspecs.h"
+#include "gimpstrokeoptions.h"
+
+#include "paint/gimppaintoptions.h"
+
+#include "gimp-intl.h"
+
+
+enum
+{
+  PROP_0,
+
+  PROP_METHOD,
+
+  PROP_STYLE,
+  PROP_WIDTH,
+  PROP_UNIT,
+  PROP_CAP_STYLE,
+  PROP_JOIN_STYLE,
+  PROP_MITER_LIMIT,
+  PROP_ANTIALIAS,
+  PROP_DASH_UNIT,
+  PROP_DASH_OFFSET,
+  PROP_DASH_INFO,
+
+  PROP_PAINT_OPTIONS,
+  PROP_EMULATE_DYNAMICS
+};
+
+enum
+{
+  DASH_INFO_CHANGED,
+  LAST_SIGNAL
+};
+
+
+typedef struct _GimpStrokeOptionsPrivate GimpStrokeOptionsPrivate;
+
+struct _GimpStrokeOptionsPrivate
+{
+  GimpStrokeMethod  method;
+
+  /*  options for method == LIBART  */
+  gdouble           width;
+  GimpUnit          unit;
+
+  GimpCapStyle      cap_style;
+  GimpJoinStyle     join_style;
+
+  gdouble           miter_limit;
+
+  gdouble           dash_offset;
+  GArray           *dash_info;
+
+  /*  options for method == PAINT_TOOL  */
+  GimpPaintOptions *paint_options;
+  gboolean          emulate_dynamics;
+};
+
+#define GET_PRIVATE(options) \
+        ((GimpStrokeOptionsPrivate *) gimp_stroke_options_get_instance_private ((GimpStrokeOptions *) (options)))
+
+
+static void   gimp_stroke_options_config_iface_init (gpointer      iface,
+                                                     gpointer      iface_data);
+
+static void   gimp_stroke_options_finalize          (GObject      *object);
+static void   gimp_stroke_options_set_property      (GObject      *object,
+                                                     guint         property_id,
+                                                     const GValue *value,
+                                                     GParamSpec   *pspec);
+static void   gimp_stroke_options_get_property      (GObject      *object,
+                                                     guint         property_id,
+                                                     GValue       *value,
+                                                     GParamSpec   *pspec);
+
+static GimpConfig * gimp_stroke_options_duplicate   (GimpConfig   *config);
+
+
+G_DEFINE_TYPE_WITH_CODE (GimpStrokeOptions, gimp_stroke_options,
+                         GIMP_TYPE_FILL_OPTIONS,
+                         G_ADD_PRIVATE (GimpStrokeOptions)
+                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_CONFIG,
+                                                gimp_stroke_options_config_iface_init))
+
+#define parent_class gimp_stroke_options_parent_class
+
+static GimpConfigInterface *parent_config_iface = NULL;
+
+static guint stroke_options_signals[LAST_SIGNAL] = { 0 };
+
+
+static void
+gimp_stroke_options_class_init (GimpStrokeOptionsClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+  GParamSpec   *array_spec;
+
+  object_class->finalize     = gimp_stroke_options_finalize;
+  object_class->set_property = gimp_stroke_options_set_property;
+  object_class->get_property = gimp_stroke_options_get_property;
+
+  klass->dash_info_changed = NULL;
+
+  stroke_options_signals[DASH_INFO_CHANGED] =
+    g_signal_new ("dash-info-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpStrokeOptionsClass, dash_info_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__ENUM,
+                  G_TYPE_NONE, 1,
+                  GIMP_TYPE_DASH_PRESET);
+
+  GIMP_CONFIG_PROP_ENUM (object_class, PROP_METHOD,
+                         "method",
+                         _("Method"),
+                         NULL,
+                         GIMP_TYPE_STROKE_METHOD,
+                         GIMP_STROKE_LINE,
+                         GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_DOUBLE (object_class, PROP_WIDTH,
+                           "width",
+                           _("Line width"),
+                           NULL,
+                           0.0, 2000.0, 6.0,
+                           GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_UNIT (object_class, PROP_UNIT,
+                         "unit",
+                         _("Unit"),
+                         NULL,
+                         TRUE, FALSE, GIMP_UNIT_PIXEL,
+                         GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_ENUM (object_class, PROP_CAP_STYLE,
+                         "cap-style",
+                         _("Cap style"),
+                         NULL,
+                         GIMP_TYPE_CAP_STYLE, GIMP_CAP_BUTT,
+                         GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_ENUM (object_class, PROP_JOIN_STYLE,
+                         "join-style",
+                         _("Join style"),
+                         NULL,
+                         GIMP_TYPE_JOIN_STYLE, GIMP_JOIN_MITER,
+                         GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_DOUBLE (object_class, PROP_MITER_LIMIT,
+                           "miter-limit",
+                           _("Miter limit"),
+                           _("Convert a mitered join to a bevelled "
+                             "join if the miter would extend to a "
+                             "distance of more than miter-limit * "
+                             "line-width from the actual join point."),
+                           0.0, 100.0, 10.0,
+                           GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_DOUBLE (object_class, PROP_DASH_OFFSET,
+                           "dash-offset",
+                           _("Dash offset"),
+                           NULL,
+                           0.0, 2000.0, 0.0,
+                           GIMP_PARAM_STATIC_STRINGS);
+
+  array_spec = g_param_spec_double ("dash-length", NULL, NULL,
+                                    0.0, 2000.0, 1.0, GIMP_PARAM_READWRITE);
+  g_object_class_install_property (object_class, PROP_DASH_INFO,
+                                   gimp_param_spec_value_array ("dash-info",
+                                                                NULL, NULL,
+                                                                array_spec,
+                                                                GIMP_PARAM_STATIC_STRINGS |
+                                                                GIMP_CONFIG_PARAM_FLAGS));
+
+  GIMP_CONFIG_PROP_OBJECT (object_class, PROP_PAINT_OPTIONS,
+                           "paint-options",
+                           NULL, NULL,
+                           GIMP_TYPE_PAINT_OPTIONS,
+                           GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_BOOLEAN (object_class, PROP_EMULATE_DYNAMICS,
+                            "emulate-brush-dynamics",
+                            _("Emulate brush dynamics"),
+                            NULL,
+                            FALSE,
+                            GIMP_PARAM_STATIC_STRINGS);
+}
+
+static void
+gimp_stroke_options_config_iface_init (gpointer  iface,
+                                       gpointer  iface_data)
+{
+  GimpConfigInterface *config_iface = (GimpConfigInterface *) iface;
+
+  parent_config_iface = g_type_interface_peek_parent (config_iface);
+
+  if (! parent_config_iface)
+    parent_config_iface = g_type_default_interface_peek (GIMP_TYPE_CONFIG);
+
+  config_iface->duplicate = gimp_stroke_options_duplicate;
+}
+
+static void
+gimp_stroke_options_init (GimpStrokeOptions *options)
+{
+}
+
+static void
+gimp_stroke_options_finalize (GObject *object)
+{
+  GimpStrokeOptionsPrivate *private = GET_PRIVATE (object);
+
+  if (private->dash_info)
+    {
+      gimp_dash_pattern_free (private->dash_info);
+      private->dash_info = NULL;
+    }
+
+  g_clear_object (&private->paint_options);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gimp_stroke_options_set_property (GObject      *object,
+                                  guint         property_id,
+                                  const GValue *value,
+                                  GParamSpec   *pspec)
+{
+  GimpStrokeOptions        *options = GIMP_STROKE_OPTIONS (object);
+  GimpStrokeOptionsPrivate *private = GET_PRIVATE (object);
+
+  switch (property_id)
+    {
+    case PROP_METHOD:
+      private->method = g_value_get_enum (value);
+      break;
+
+    case PROP_WIDTH:
+      private->width = g_value_get_double (value);
+      break;
+    case PROP_UNIT:
+      private->unit = g_value_get_int (value);
+      break;
+    case PROP_CAP_STYLE:
+      private->cap_style = g_value_get_enum (value);
+      break;
+    case PROP_JOIN_STYLE:
+      private->join_style = g_value_get_enum (value);
+      break;
+    case PROP_MITER_LIMIT:
+      private->miter_limit = g_value_get_double (value);
+      break;
+    case PROP_DASH_OFFSET:
+      private->dash_offset = g_value_get_double (value);
+      break;
+    case PROP_DASH_INFO:
+      {
+        GimpValueArray *value_array = g_value_get_boxed (value);
+        GArray         *pattern;
+
+        pattern = gimp_dash_pattern_from_value_array (value_array);
+        gimp_stroke_options_take_dash_pattern (options, GIMP_DASH_CUSTOM,
+                                               pattern);
+      }
+      break;
+
+    case PROP_PAINT_OPTIONS:
+      if (private->paint_options)
+        g_object_unref (private->paint_options);
+      private->paint_options = g_value_dup_object (value);
+      break;
+    case PROP_EMULATE_DYNAMICS:
+      private->emulate_dynamics = g_value_get_boolean (value);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_stroke_options_get_property (GObject    *object,
+                                  guint       property_id,
+                                  GValue     *value,
+                                  GParamSpec *pspec)
+{
+  GimpStrokeOptionsPrivate *private = GET_PRIVATE (object);
+
+  switch (property_id)
+    {
+    case PROP_METHOD:
+      g_value_set_enum (value, private->method);
+      break;
+
+    case PROP_WIDTH:
+      g_value_set_double (value, private->width);
+      break;
+    case PROP_UNIT:
+      g_value_set_int (value, private->unit);
+      break;
+    case PROP_CAP_STYLE:
+      g_value_set_enum (value, private->cap_style);
+      break;
+    case PROP_JOIN_STYLE:
+      g_value_set_enum (value, private->join_style);
+      break;
+    case PROP_MITER_LIMIT:
+      g_value_set_double (value, private->miter_limit);
+      break;
+    case PROP_DASH_OFFSET:
+      g_value_set_double (value, private->dash_offset);
+      break;
+    case PROP_DASH_INFO:
+      {
+        GimpValueArray *value_array;
+
+        value_array = gimp_dash_pattern_to_value_array (private->dash_info);
+        g_value_take_boxed (value, value_array);
+      }
+      break;
+
+    case PROP_PAINT_OPTIONS:
+      g_value_set_object (value, private->paint_options);
+      break;
+    case PROP_EMULATE_DYNAMICS:
+      g_value_set_boolean (value, private->emulate_dynamics);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static GimpConfig *
+gimp_stroke_options_duplicate (GimpConfig *config)
+{
+  GimpStrokeOptions        *options = GIMP_STROKE_OPTIONS (config);
+  GimpStrokeOptionsPrivate *private = GET_PRIVATE (options);
+  GimpStrokeOptions        *new_options;
+
+  new_options = GIMP_STROKE_OPTIONS (parent_config_iface->duplicate (config));
+
+  if (private->paint_options)
+    {
+      GObject *paint_options;
+
+      paint_options = gimp_config_duplicate (GIMP_CONFIG (private->paint_options));
+      g_object_set (new_options, "paint-options", paint_options, NULL);
+      g_object_unref (paint_options);
+    }
+
+  return GIMP_CONFIG (new_options);
+}
+
+
+/*  public functions  */
+
+GimpStrokeOptions *
+gimp_stroke_options_new (Gimp        *gimp,
+                         GimpContext *context,
+                         gboolean     use_context_color)
+{
+  GimpPaintInfo     *paint_info = NULL;
+  GimpStrokeOptions *options;
+
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+  g_return_val_if_fail (context == NULL || GIMP_IS_CONTEXT (context), NULL);
+  g_return_val_if_fail (use_context_color == FALSE || context != NULL, NULL);
+
+  if (context)
+    paint_info = gimp_context_get_paint_info (context);
+
+  if (! paint_info)
+    paint_info = gimp_paint_info_get_standard (gimp);
+
+  options = g_object_new (GIMP_TYPE_STROKE_OPTIONS,
+                          "gimp",       gimp,
+                          "paint-info", paint_info,
+                          NULL);
+
+  if (use_context_color)
+    {
+      gimp_context_define_properties (GIMP_CONTEXT (options),
+                                      GIMP_CONTEXT_PROP_MASK_FOREGROUND |
+                                      GIMP_CONTEXT_PROP_MASK_PATTERN,
+                                      FALSE);
+
+      gimp_context_set_parent (GIMP_CONTEXT (options), context);
+    }
+
+  return options;
+}
+
+GimpStrokeMethod
+gimp_stroke_options_get_method (GimpStrokeOptions *options)
+{
+  g_return_val_if_fail (GIMP_IS_STROKE_OPTIONS (options),
+                        GIMP_STROKE_LINE);
+
+  return GET_PRIVATE (options)->method;
+}
+
+gdouble
+gimp_stroke_options_get_width (GimpStrokeOptions *options)
+{
+  g_return_val_if_fail (GIMP_IS_STROKE_OPTIONS (options), 1.0);
+
+  return GET_PRIVATE (options)->width;
+}
+
+GimpUnit
+gimp_stroke_options_get_unit (GimpStrokeOptions *options)
+{
+  g_return_val_if_fail (GIMP_IS_STROKE_OPTIONS (options), GIMP_UNIT_PIXEL);
+
+  return GET_PRIVATE (options)->unit;
+}
+
+GimpCapStyle
+gimp_stroke_options_get_cap_style (GimpStrokeOptions *options)
+{
+  g_return_val_if_fail (GIMP_IS_STROKE_OPTIONS (options), GIMP_CAP_BUTT);
+
+  return GET_PRIVATE (options)->cap_style;
+}
+
+GimpJoinStyle
+gimp_stroke_options_get_join_style (GimpStrokeOptions *options)
+{
+  g_return_val_if_fail (GIMP_IS_STROKE_OPTIONS (options), GIMP_JOIN_MITER);
+
+  return GET_PRIVATE (options)->join_style;
+}
+
+gdouble
+gimp_stroke_options_get_miter_limit (GimpStrokeOptions *options)
+{
+  g_return_val_if_fail (GIMP_IS_STROKE_OPTIONS (options), 1.0);
+
+  return GET_PRIVATE (options)->miter_limit;
+}
+
+gdouble
+gimp_stroke_options_get_dash_offset (GimpStrokeOptions *options)
+{
+  g_return_val_if_fail (GIMP_IS_STROKE_OPTIONS (options), 0.0);
+
+  return GET_PRIVATE (options)->dash_offset;
+}
+
+GArray *
+gimp_stroke_options_get_dash_info (GimpStrokeOptions *options)
+{
+  g_return_val_if_fail (GIMP_IS_STROKE_OPTIONS (options), NULL);
+
+  return GET_PRIVATE (options)->dash_info;
+}
+
+GimpPaintOptions *
+gimp_stroke_options_get_paint_options (GimpStrokeOptions *options)
+{
+  g_return_val_if_fail (GIMP_IS_STROKE_OPTIONS (options), NULL);
+
+  return GET_PRIVATE (options)->paint_options;
+}
+
+gboolean
+gimp_stroke_options_get_emulate_dynamics (GimpStrokeOptions *options)
+{
+  g_return_val_if_fail (GIMP_IS_STROKE_OPTIONS (options), FALSE);
+
+  return GET_PRIVATE (options)->emulate_dynamics;
+}
+
+/**
+ * gimp_stroke_options_take_dash_pattern:
+ * @options: a #GimpStrokeOptions object
+ * @preset: a value out of the #GimpDashPreset enum
+ * @pattern: a #GArray or %NULL if @preset is not %GIMP_DASH_CUSTOM
+ *
+ * Sets the dash pattern. Either a @preset is passed and @pattern is
+ * %NULL or @preset is %GIMP_DASH_CUSTOM and @pattern is the #GArray
+ * to use as the dash pattern. Note that this function takes ownership
+ * of the passed pattern.
+ */
+void
+gimp_stroke_options_take_dash_pattern (GimpStrokeOptions *options,
+                                       GimpDashPreset     preset,
+                                       GArray            *pattern)
+{
+  GimpStrokeOptionsPrivate *private;
+
+  g_return_if_fail (GIMP_IS_STROKE_OPTIONS (options));
+  g_return_if_fail (preset == GIMP_DASH_CUSTOM || pattern == NULL);
+
+  private = GET_PRIVATE (options);
+
+  if (preset != GIMP_DASH_CUSTOM)
+    pattern = gimp_dash_pattern_new_from_preset (preset);
+
+  if (private->dash_info)
+    gimp_dash_pattern_free (private->dash_info);
+
+  private->dash_info = pattern;
+
+  g_object_notify (G_OBJECT (options), "dash-info");
+
+  g_signal_emit (options, stroke_options_signals [DASH_INFO_CHANGED], 0,
+                 preset);
+}
+
+void
+gimp_stroke_options_prepare (GimpStrokeOptions *options,
+                             GimpContext       *context,
+                             GimpPaintOptions  *paint_options)
+{
+  GimpStrokeOptionsPrivate *private;
+
+  g_return_if_fail (GIMP_IS_STROKE_OPTIONS (options));
+  g_return_if_fail (GIMP_IS_CONTEXT (context));
+  g_return_if_fail (paint_options == NULL ||
+                    GIMP_IS_PAINT_OPTIONS (paint_options));
+
+  private = GET_PRIVATE (options);
+
+  switch (private->method)
+    {
+    case GIMP_STROKE_LINE:
+      break;
+
+    case GIMP_STROKE_PAINT_METHOD:
+      {
+        GimpPaintInfo *paint_info = GIMP_CONTEXT (options)->paint_info;
+
+        if (paint_options)
+          {
+            g_return_if_fail (paint_info == paint_options->paint_info);
+
+            /*  undefine the paint-relevant context properties and get them
+             *  from the passed context
+             */
+            gimp_context_define_properties (GIMP_CONTEXT (paint_options),
+                                            GIMP_CONTEXT_PROP_MASK_PAINT,
+                                            FALSE);
+            gimp_context_set_parent (GIMP_CONTEXT (paint_options), context);
+
+            g_object_ref (paint_options);
+          }
+        else
+          {
+            GimpCoreConfig      *config       = context->gimp->config;
+            GimpContextPropMask  global_props = 0;
+
+            paint_options =
+              gimp_config_duplicate (GIMP_CONFIG (paint_info->paint_options));
+
+            /*  FG and BG are always shared between all tools  */
+            global_props |= GIMP_CONTEXT_PROP_MASK_FOREGROUND;
+            global_props |= GIMP_CONTEXT_PROP_MASK_BACKGROUND;
+
+            if (config->global_brush)
+              global_props |= GIMP_CONTEXT_PROP_MASK_BRUSH;
+            if (config->global_dynamics)
+              global_props |= GIMP_CONTEXT_PROP_MASK_DYNAMICS;
+            if (config->global_pattern)
+              global_props |= GIMP_CONTEXT_PROP_MASK_PATTERN;
+            if (config->global_palette)
+              global_props |= GIMP_CONTEXT_PROP_MASK_PALETTE;
+            if (config->global_gradient)
+              global_props |= GIMP_CONTEXT_PROP_MASK_GRADIENT;
+            if (config->global_font)
+              global_props |= GIMP_CONTEXT_PROP_MASK_FONT;
+
+            gimp_context_copy_properties (context,
+                                          GIMP_CONTEXT (paint_options),
+                                          global_props);
+          }
+
+        g_object_set (options, "paint-options", paint_options, NULL);
+        g_object_unref (paint_options);
+      }
+      break;
+
+    default:
+      g_return_if_reached ();
+    }
+}
+
+void
+gimp_stroke_options_finish (GimpStrokeOptions *options)
+{
+  g_return_if_fail (GIMP_IS_STROKE_OPTIONS (options));
+
+  g_object_set (options, "paint-options", NULL, NULL);
+}
diff --git a/app/core/gimpstrokeoptions.h b/app/core/gimpstrokeoptions.h
new file mode 100644
index 0000000..f5210e8
--- /dev/null
+++ b/app/core/gimpstrokeoptions.h
@@ -0,0 +1,81 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1999 Spencer Kimball and Peter Mattis
+ *
+ * gimpstrokeoptions.h
+ * Copyright (C) 2003 Simon Budig
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_STROKE_OPTIONS_H__
+#define __GIMP_STROKE_OPTIONS_H__
+
+
+#include "gimpfilloptions.h"
+
+
+#define GIMP_TYPE_STROKE_OPTIONS            (gimp_stroke_options_get_type ())
+#define GIMP_STROKE_OPTIONS(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_STROKE_OPTIONS, GimpStrokeOptions))
+#define GIMP_STROKE_OPTIONS_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_STROKE_OPTIONS, GimpStrokeOptionsClass))
+#define GIMP_IS_STROKE_OPTIONS(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_STROKE_OPTIONS))
+#define GIMP_IS_STROKE_OPTIONS_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_STROKE_OPTIONS))
+#define GIMP_STROKE_OPTIONS_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_STROKE_OPTIONS, GimpStrokeOptionsClass))
+
+
+typedef struct _GimpStrokeOptionsClass GimpStrokeOptionsClass;
+
+struct _GimpStrokeOptions
+{
+  GimpFillOptions  parent_instance;
+};
+
+struct _GimpStrokeOptionsClass
+{
+  GimpFillOptionsClass  parent_class;
+
+  void (* dash_info_changed) (GimpStrokeOptions *stroke_options,
+                              GimpDashPreset     preset);
+};
+
+
+GType               gimp_stroke_options_get_type             (void) G_GNUC_CONST;
+
+GimpStrokeOptions * gimp_stroke_options_new                  (Gimp              *gimp,
+                                                              GimpContext       *context,
+                                                              gboolean           use_context_color);
+
+GimpStrokeMethod    gimp_stroke_options_get_method           (GimpStrokeOptions *options);
+
+gdouble             gimp_stroke_options_get_width            (GimpStrokeOptions *options);
+GimpUnit            gimp_stroke_options_get_unit             (GimpStrokeOptions *options);
+GimpCapStyle        gimp_stroke_options_get_cap_style        (GimpStrokeOptions *options);
+GimpJoinStyle       gimp_stroke_options_get_join_style       (GimpStrokeOptions *options);
+gdouble             gimp_stroke_options_get_miter_limit      (GimpStrokeOptions *options);
+gdouble             gimp_stroke_options_get_dash_offset      (GimpStrokeOptions *options);
+GArray            * gimp_stroke_options_get_dash_info        (GimpStrokeOptions *options);
+
+GimpPaintOptions  * gimp_stroke_options_get_paint_options    (GimpStrokeOptions *options);
+gboolean            gimp_stroke_options_get_emulate_dynamics (GimpStrokeOptions *options);
+
+void                gimp_stroke_options_take_dash_pattern    (GimpStrokeOptions *options,
+                                                              GimpDashPreset     preset,
+                                                              GArray            *pattern);
+
+void                gimp_stroke_options_prepare              (GimpStrokeOptions *options,
+                                                              GimpContext       *context,
+                                                              GimpPaintOptions  *paint_options);
+void                gimp_stroke_options_finish               (GimpStrokeOptions *options);
+
+
+#endif /* __GIMP_STROKE_OPTIONS_H__ */
diff --git a/app/core/gimpsubprogress.c b/app/core/gimpsubprogress.c
new file mode 100644
index 0000000..3183f61
--- /dev/null
+++ b/app/core/gimpsubprogress.c
@@ -0,0 +1,317 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <glib-object.h>
+
+#include "core-types.h"
+
+#include "core/gimpsubprogress.h"
+#include "core/gimpprogress.h"
+
+
+enum
+{
+  PROP_0,
+  PROP_PROGRESS
+};
+
+
+static void           gimp_sub_progress_iface_init    (GimpProgressInterface *iface);
+
+static void           gimp_sub_progress_finalize      (GObject             *object);
+static void           gimp_sub_progress_set_property  (GObject             *object,
+                                                       guint                property_id,
+                                                       const GValue        *value,
+                                                       GParamSpec          *pspec);
+static void           gimp_sub_progress_get_property  (GObject             *object,
+                                                       guint                property_id,
+                                                       GValue              *value,
+                                                       GParamSpec          *pspec);
+
+static GimpProgress * gimp_sub_progress_start         (GimpProgress        *progress,
+                                                       gboolean             cancellable,
+                                                       const gchar         *message);
+static void           gimp_sub_progress_end           (GimpProgress        *progress);
+static gboolean       gimp_sub_progress_is_active     (GimpProgress        *progress);
+static void           gimp_sub_progress_set_text      (GimpProgress        *progress,
+                                                       const gchar         *message);
+static void           gimp_sub_progress_set_value     (GimpProgress        *progress,
+                                                       gdouble              percentage);
+static gdouble        gimp_sub_progress_get_value     (GimpProgress        *progress);
+static void           gimp_sub_progress_pulse         (GimpProgress        *progress);
+static guint32        gimp_sub_progress_get_window_id (GimpProgress        *progress);
+static gboolean       gimp_sub_progress_message       (GimpProgress        *progress,
+                                                       Gimp                *gimp,
+                                                       GimpMessageSeverity  severity,
+                                                       const gchar         *domain,
+                                                       const gchar         *message);
+
+
+G_DEFINE_TYPE_WITH_CODE (GimpSubProgress, gimp_sub_progress, G_TYPE_OBJECT,
+                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_PROGRESS,
+                                                gimp_sub_progress_iface_init))
+
+#define parent_class gimp_sub_progress_parent_class
+
+
+static void
+gimp_sub_progress_class_init (GimpSubProgressClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  object_class->finalize     = gimp_sub_progress_finalize;
+  object_class->set_property = gimp_sub_progress_set_property;
+  object_class->get_property = gimp_sub_progress_get_property;
+
+  g_object_class_install_property (object_class, PROP_PROGRESS,
+                                   g_param_spec_object ("progress",
+                                                        NULL, NULL,
+                                                        GIMP_TYPE_PROGRESS,
+                                                        G_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT_ONLY));
+}
+
+static void
+gimp_sub_progress_init (GimpSubProgress *sub)
+{
+  sub->progress = NULL;
+  sub->start    = 0.0;
+  sub->end      = 1.0;
+}
+
+static void
+gimp_sub_progress_finalize (GObject *object)
+{
+  GimpSubProgress *sub = GIMP_SUB_PROGRESS (object);
+
+  g_clear_object (&sub->progress);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gimp_sub_progress_iface_init (GimpProgressInterface *iface)
+{
+  iface->start         = gimp_sub_progress_start;
+  iface->end           = gimp_sub_progress_end;
+  iface->is_active     = gimp_sub_progress_is_active;
+  iface->set_text      = gimp_sub_progress_set_text;
+  iface->set_value     = gimp_sub_progress_set_value;
+  iface->get_value     = gimp_sub_progress_get_value;
+  iface->pulse         = gimp_sub_progress_pulse;
+  iface->get_window_id = gimp_sub_progress_get_window_id;
+  iface->message       = gimp_sub_progress_message;
+}
+
+static void
+gimp_sub_progress_set_property (GObject      *object,
+                                guint         property_id,
+                                const GValue *value,
+                                GParamSpec   *pspec)
+{
+  GimpSubProgress *sub = GIMP_SUB_PROGRESS (object);
+
+  switch (property_id)
+    {
+    case PROP_PROGRESS:
+      g_return_if_fail (sub->progress == NULL);
+      sub->progress = g_value_dup_object (value);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_sub_progress_get_property (GObject    *object,
+                                guint       property_id,
+                                GValue     *value,
+                                GParamSpec *pspec)
+{
+  GimpSubProgress *sub = GIMP_SUB_PROGRESS (object);
+
+  switch (property_id)
+    {
+    case PROP_PROGRESS:
+      g_value_set_object (value, sub->progress);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static GimpProgress *
+gimp_sub_progress_start (GimpProgress *progress,
+                         gboolean      cancellable,
+                         const gchar  *message)
+{
+  /* does nothing */
+  return NULL;
+}
+
+static void
+gimp_sub_progress_end (GimpProgress *progress)
+{
+  /* does nothing */
+}
+
+static gboolean
+gimp_sub_progress_is_active (GimpProgress *progress)
+{
+  GimpSubProgress *sub = GIMP_SUB_PROGRESS (progress);
+
+  if (sub->progress)
+    return gimp_progress_is_active (sub->progress);
+
+  return FALSE;
+}
+
+static void
+gimp_sub_progress_set_text (GimpProgress *progress,
+                            const gchar  *message)
+{
+  /* does nothing */
+}
+
+static void
+gimp_sub_progress_set_value (GimpProgress *progress,
+                             gdouble       percentage)
+{
+  GimpSubProgress *sub = GIMP_SUB_PROGRESS (progress);
+
+  if (sub->progress)
+    gimp_progress_set_value (sub->progress,
+                             sub->start + percentage * (sub->end - sub->start));
+}
+
+static gdouble
+gimp_sub_progress_get_value (GimpProgress *progress)
+{
+  GimpSubProgress *sub = GIMP_SUB_PROGRESS (progress);
+
+  if (sub->progress)
+    return gimp_progress_get_value (sub->progress);
+
+  return 0.0;
+}
+
+static void
+gimp_sub_progress_pulse (GimpProgress *progress)
+{
+  GimpSubProgress *sub = GIMP_SUB_PROGRESS (progress);
+
+  if (sub->progress)
+    gimp_progress_pulse (sub->progress);
+}
+
+static guint32
+gimp_sub_progress_get_window_id (GimpProgress *progress)
+{
+  GimpSubProgress *sub = GIMP_SUB_PROGRESS (progress);
+
+  if (sub->progress)
+    return gimp_progress_get_window_id (sub->progress);
+
+  return 0;
+}
+
+static gboolean
+gimp_sub_progress_message (GimpProgress        *progress,
+                           Gimp                *gimp,
+                           GimpMessageSeverity  severity,
+                           const gchar         *domain,
+                           const gchar         *message)
+{
+  GimpSubProgress *sub = GIMP_SUB_PROGRESS (progress);
+
+  if (sub->progress)
+    return gimp_progress_message (sub->progress,
+                                  gimp, severity, domain, message);
+
+  return FALSE;
+}
+
+/**
+ * gimp_sub_progress_new:
+ * @progress: parent progress or %NULL
+ *
+ * GimpSubProgress implements the GimpProgress interface and can be
+ * used wherever a GimpProgress is needed. It maps progress
+ * information to a sub-range of its parent @progress. This is useful
+ * when an action breaks down into multiple sub-actions that itself
+ * need a #GimpProgress pointer. See gimp_image_scale() for an example.
+ *
+ * Return value: a new #GimpProgress object
+ */
+GimpProgress *
+gimp_sub_progress_new (GimpProgress *progress)
+{
+  GimpSubProgress *sub;
+
+  g_return_val_if_fail (progress == NULL || GIMP_IS_PROGRESS (progress), NULL);
+
+  sub = g_object_new (GIMP_TYPE_SUB_PROGRESS,
+                      "progress", progress,
+                      NULL);
+
+  return GIMP_PROGRESS (sub);
+}
+
+/**
+ * gimp_sub_progress_set_range:
+ * @start: start value of range on the parent process
+ * @end:   end value of range on the parent process
+ *
+ * Sets a range on the parent progress that this @progress should be
+ * mapped to.
+ */
+void
+gimp_sub_progress_set_range (GimpSubProgress *progress,
+                             gdouble          start,
+                             gdouble          end)
+{
+  g_return_if_fail (GIMP_IS_SUB_PROGRESS (progress));
+  g_return_if_fail (start < end);
+
+  progress->start = start;
+  progress->end   = end;
+}
+
+/**
+ * gimp_sub_progress_set_step:
+ * @index:     step index
+ * @num_steps: number of steps
+ *
+ * A more convenient form of gimp_sub_progress_set_range().
+ */
+void
+gimp_sub_progress_set_step (GimpSubProgress *progress,
+                            gint             index,
+                            gint             num_steps)
+{
+  g_return_if_fail (GIMP_IS_SUB_PROGRESS (progress));
+  g_return_if_fail (index < num_steps && num_steps > 0);
+
+  progress->start = (gdouble) index / num_steps;
+  progress->end   = (gdouble) (index + 1) / num_steps;
+}
diff --git a/app/core/gimpsubprogress.h b/app/core/gimpsubprogress.h
new file mode 100644
index 0000000..c031182
--- /dev/null
+++ b/app/core/gimpsubprogress.h
@@ -0,0 +1,59 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_SUB_PROGRESS_H__
+#define __GIMP_SUB_PROGRESS_H__
+
+
+#define GIMP_TYPE_SUB_PROGRESS            (gimp_sub_progress_get_type ())
+#define GIMP_SUB_PROGRESS(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_SUB_PROGRESS, GimpSubProgress))
+#define GIMP_SUB_PROGRESS_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_SUB_PROGRESS, GimpSubProgressClass))
+#define GIMP_IS_SUB_PROGRESS(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_SUB_PROGRESS))
+#define GIMP_IS_SUB_PROGRESS_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_SUB_PROGRESS))
+#define GIMP_SUB_PROGRESS_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_SUB_PROGRESS, GimpSubProgressClass))
+
+
+typedef struct _GimpSubProgressClass GimpSubProgressClass;
+
+struct _GimpSubProgress
+{
+  GObject       parent_instance;
+
+  GimpProgress *progress;
+  gdouble       start;
+  gdouble       end;
+};
+
+struct _GimpSubProgressClass
+{
+  GObjectClass  parent_class;
+};
+
+
+GType          gimp_sub_progress_get_type (void) G_GNUC_CONST;
+
+GimpProgress * gimp_sub_progress_new       (GimpProgress    *progress);
+void           gimp_sub_progress_set_range (GimpSubProgress *progress,
+                                            gdouble          start,
+                                            gdouble          end);
+void           gimp_sub_progress_set_step  (GimpSubProgress *progress,
+                                            gint             index,
+                                            gint             num_steps);
+
+
+
+#endif /* __GIMP_SUB_PROGRESS_H__ */
diff --git a/app/core/gimpsymmetry-mandala.c b/app/core/gimpsymmetry-mandala.c
new file mode 100644
index 0000000..668819a
--- /dev/null
+++ b/app/core/gimpsymmetry-mandala.c
@@ -0,0 +1,574 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpsymmetry-mandala.c
+ * Copyright (C) 2015 Jehan <jehan@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <cairo.h>
+#include <gegl.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "libgimpconfig/gimpconfig.h"
+#include "libgimpmath/gimpmath.h"
+
+#include "core-types.h"
+
+#include "gimp.h"
+#include "gimp-cairo.h"
+#include "gimpdrawable.h"
+#include "gimpguide.h"
+#include "gimpimage.h"
+#include "gimpimage-guides.h"
+#include "gimpimage-symmetry.h"
+#include "gimpitem.h"
+#include "gimpsymmetry-mandala.h"
+
+#include "gimp-intl.h"
+
+
+enum
+{
+  PROP_0,
+  PROP_CENTER_X,
+  PROP_CENTER_Y,
+  PROP_SIZE,
+  PROP_DISABLE_TRANSFORMATION,
+  PROP_ENABLE_REFLECTION,
+};
+
+
+/* Local function prototypes */
+
+static void       gimp_mandala_constructed        (GObject      *object);
+static void       gimp_mandala_finalize           (GObject      *object);
+static void       gimp_mandala_set_property       (GObject      *object,
+                                                   guint         property_id,
+                                                   const GValue *value,
+                                                   GParamSpec   *pspec);
+static void       gimp_mandala_get_property       (GObject      *object,
+                                                   guint         property_id,
+                                                   GValue       *value,
+                                                   GParamSpec   *pspec);
+static void       gimp_mandala_active_changed     (GimpSymmetry *sym);
+
+static void       gimp_mandala_add_guide          (GimpMandala         *mandala,
+                                                   GimpOrientationType  orientation);
+static void       gimp_mandala_remove_guide       (GimpMandala         *mandala,
+                                                   GimpOrientationType  orientation);
+static void       gimp_mandala_guide_removed_cb   (GObject      *object,
+                                                   GimpMandala  *mandala);
+static void       gimp_mandala_guide_position_cb  (GObject      *object,
+                                                   GParamSpec   *pspec,
+                                                   GimpMandala  *mandala);
+
+static void       gimp_mandala_update_strokes     (GimpSymmetry *mandala,
+                                                   GimpDrawable *drawable,
+                                                   GimpCoords   *origin);
+static void       gimp_mandala_get_transform      (GimpSymmetry *mandala,
+                                                   gint          stroke,
+                                                   gdouble      *angle,
+                                                   gboolean     *reflect);
+static void    gimp_mandala_image_size_changed_cb (GimpImage    *image,
+                                                   gint          previous_origin_x,
+                                                   gint          previous_origin_y,
+                                                   gint          previous_width,
+                                                   gint          previous_height,
+                                                   GimpSymmetry *sym);
+
+
+G_DEFINE_TYPE (GimpMandala, gimp_mandala, GIMP_TYPE_SYMMETRY)
+
+#define parent_class gimp_mandala_parent_class
+
+
+static void
+gimp_mandala_class_init (GimpMandalaClass *klass)
+{
+  GObjectClass      *object_class   = G_OBJECT_CLASS (klass);
+  GimpSymmetryClass *symmetry_class = GIMP_SYMMETRY_CLASS (klass);
+  GParamSpec        *pspec;
+
+  object_class->constructed         = gimp_mandala_constructed;
+  object_class->finalize            = gimp_mandala_finalize;
+  object_class->set_property        = gimp_mandala_set_property;
+  object_class->get_property        = gimp_mandala_get_property;
+
+  symmetry_class->label             = _("Mandala");
+  symmetry_class->update_strokes    = gimp_mandala_update_strokes;
+  symmetry_class->get_transform     = gimp_mandala_get_transform;
+  symmetry_class->active_changed    = gimp_mandala_active_changed;
+
+  GIMP_CONFIG_PROP_DOUBLE (object_class, PROP_CENTER_X,
+                           "center-x",
+                           _("Center abscissa"),
+                           NULL,
+                           0.0, G_MAXDOUBLE, 0.0,
+                           GIMP_PARAM_STATIC_STRINGS |
+                           GIMP_SYMMETRY_PARAM_GUI);
+
+  pspec = g_object_class_find_property (object_class, "center-x");
+  gegl_param_spec_set_property_key (pspec, "unit", "pixel-coordinate");
+  gegl_param_spec_set_property_key (pspec, "axis", "x");
+
+  GIMP_CONFIG_PROP_DOUBLE (object_class, PROP_CENTER_Y,
+                           "center-y",
+                           _("Center ordinate"),
+                           NULL,
+                           0.0, G_MAXDOUBLE, 0.0,
+                           GIMP_PARAM_STATIC_STRINGS |
+                           GIMP_SYMMETRY_PARAM_GUI);
+
+  pspec = g_object_class_find_property (object_class, "center-y");
+  gegl_param_spec_set_property_key (pspec, "unit", "pixel-coordinate");
+  gegl_param_spec_set_property_key (pspec, "axis", "y");
+
+  GIMP_CONFIG_PROP_INT (object_class, PROP_SIZE,
+                        "size",
+                        _("Number of points"),
+                        NULL,
+                        1, 100, 6.0,
+                        GIMP_PARAM_STATIC_STRINGS |
+                        GIMP_SYMMETRY_PARAM_GUI);
+
+  GIMP_CONFIG_PROP_BOOLEAN (object_class, PROP_DISABLE_TRANSFORMATION,
+                            "disable-transformation",
+                            _("Disable brush transform"),
+                            _("Disable brush rotation"),
+                            FALSE,
+                            GIMP_PARAM_STATIC_STRINGS |
+                            GIMP_SYMMETRY_PARAM_GUI);
+
+  GIMP_CONFIG_PROP_BOOLEAN (object_class, PROP_ENABLE_REFLECTION,
+                            "enable-reflection",
+                            _("Kaleidoscope"),
+                            _("Reflect consecutive strokes"),
+                            FALSE,
+                            GIMP_PARAM_STATIC_STRINGS |
+                            GIMP_SYMMETRY_PARAM_GUI);
+}
+
+static void
+gimp_mandala_init (GimpMandala *mandala)
+{
+}
+
+static void
+gimp_mandala_constructed (GObject *object)
+{
+  GimpSymmetry *sym = GIMP_SYMMETRY (object);
+
+  g_signal_connect_object (sym->image, "size-changed-detailed",
+                           G_CALLBACK (gimp_mandala_image_size_changed_cb),
+                           sym, 0);
+}
+
+static void
+gimp_mandala_finalize (GObject *object)
+{
+  GimpMandala  *mandala = GIMP_MANDALA (object);
+
+  g_clear_object (&mandala->horizontal_guide);
+  g_clear_object (&mandala->vertical_guide);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gimp_mandala_set_property (GObject      *object,
+                           guint         property_id,
+                           const GValue *value,
+                           GParamSpec   *pspec)
+{
+  GimpMandala *mandala = GIMP_MANDALA (object);
+  GimpImage   *image   = GIMP_SYMMETRY (mandala)->image;
+
+  switch (property_id)
+    {
+    case PROP_CENTER_X:
+      if (g_value_get_double (value) > 0.0 &&
+          g_value_get_double (value) < (gdouble) gimp_image_get_width (image))
+        {
+          mandala->center_x = g_value_get_double (value);
+
+          if (mandala->vertical_guide)
+            {
+              g_signal_handlers_block_by_func (mandala->vertical_guide,
+                                               gimp_mandala_guide_position_cb,
+                                               mandala);
+              gimp_image_move_guide (image, mandala->vertical_guide,
+                                     mandala->center_x,
+                                     FALSE);
+              g_signal_handlers_unblock_by_func (mandala->vertical_guide,
+                                                 gimp_mandala_guide_position_cb,
+                                                 mandala);
+            }
+        }
+      break;
+
+    case PROP_CENTER_Y:
+      if (g_value_get_double (value) > 0.0 &&
+          g_value_get_double (value) < (gdouble) gimp_image_get_height (image))
+        {
+          mandala->center_y = g_value_get_double (value);
+
+          if (mandala->horizontal_guide)
+            {
+              g_signal_handlers_block_by_func (mandala->horizontal_guide,
+                                               gimp_mandala_guide_position_cb,
+                                               mandala);
+              gimp_image_move_guide (image, mandala->horizontal_guide,
+                                     mandala->center_y,
+                                     FALSE);
+              g_signal_handlers_unblock_by_func (mandala->horizontal_guide,
+                                                 gimp_mandala_guide_position_cb,
+                                                 mandala);
+            }
+        }
+      break;
+
+    case PROP_SIZE:
+      mandala->size = g_value_get_int (value);
+      break;
+
+    case PROP_DISABLE_TRANSFORMATION:
+      mandala->disable_transformation = g_value_get_boolean (value);
+      break;
+
+    case PROP_ENABLE_REFLECTION:
+      mandala->enable_reflection = g_value_get_boolean (value);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_mandala_get_property (GObject    *object,
+                           guint       property_id,
+                           GValue     *value,
+                           GParamSpec *pspec)
+{
+  GimpMandala *mandala = GIMP_MANDALA (object);
+
+  switch (property_id)
+    {
+    case PROP_CENTER_X:
+      g_value_set_double (value, mandala->center_x);
+      break;
+    case PROP_CENTER_Y:
+      g_value_set_double (value, mandala->center_y);
+      break;
+    case PROP_SIZE:
+      g_value_set_int (value, mandala->size);
+      break;
+    case PROP_DISABLE_TRANSFORMATION:
+      g_value_set_boolean (value, mandala->disable_transformation);
+      break;
+    case PROP_ENABLE_REFLECTION:
+      g_value_set_boolean (value, mandala->enable_reflection);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_mandala_active_changed (GimpSymmetry *sym)
+{
+  GimpMandala *mandala = GIMP_MANDALA (sym);
+
+  if (sym->active)
+    {
+      if (! mandala->horizontal_guide)
+        gimp_mandala_add_guide (mandala, GIMP_ORIENTATION_HORIZONTAL);
+
+      if (! mandala->vertical_guide)
+        gimp_mandala_add_guide (mandala, GIMP_ORIENTATION_VERTICAL);
+    }
+  else
+    {
+      if (mandala->horizontal_guide)
+        gimp_mandala_remove_guide (mandala, GIMP_ORIENTATION_HORIZONTAL);
+
+      if (mandala->vertical_guide)
+        gimp_mandala_remove_guide (mandala, GIMP_ORIENTATION_VERTICAL);
+    }
+}
+
+static void
+gimp_mandala_add_guide (GimpMandala         *mandala,
+                        GimpOrientationType  orientation)
+{
+  GimpSymmetry *sym = GIMP_SYMMETRY (mandala);
+  GimpImage    *image;
+  Gimp         *gimp;
+  GimpGuide    *guide;
+  gint          position;
+
+  image = sym->image;
+  gimp  = image->gimp;
+
+  guide = gimp_guide_custom_new (orientation,
+                                 gimp->next_guide_ID++,
+                                 GIMP_GUIDE_STYLE_MANDALA);
+
+  if (orientation == GIMP_ORIENTATION_HORIZONTAL)
+    {
+      mandala->horizontal_guide = guide;
+
+      /* Mandala guide position at first activation is at canvas middle. */
+      if (mandala->center_y < 1.0)
+        mandala->center_y = (gdouble) gimp_image_get_height (image) / 2.0;
+
+      position = (gint) mandala->center_y;
+    }
+  else
+    {
+      mandala->vertical_guide = guide;
+
+      /* Mandala guide position at first activation is at canvas middle. */
+      if (mandala->center_x < 1.0)
+        mandala->center_x = (gdouble) gimp_image_get_width (image) / 2.0;
+
+      position = (gint) mandala->center_x;
+    }
+
+  g_signal_connect (guide, "removed",
+                    G_CALLBACK (gimp_mandala_guide_removed_cb),
+                    mandala);
+
+  gimp_image_add_guide (image, guide, position);
+
+  g_signal_connect (guide, "notify::position",
+                    G_CALLBACK (gimp_mandala_guide_position_cb),
+                    mandala);
+}
+
+static void
+gimp_mandala_remove_guide (GimpMandala         *mandala,
+                           GimpOrientationType  orientation)
+{
+  GimpSymmetry *sym = GIMP_SYMMETRY (mandala);
+  GimpImage    *image;
+  GimpGuide    *guide;
+
+  image = sym->image;
+  guide = (orientation == GIMP_ORIENTATION_HORIZONTAL) ?
+    mandala->horizontal_guide : mandala->vertical_guide;
+
+  g_signal_handlers_disconnect_by_func (guide,
+                                        gimp_mandala_guide_removed_cb,
+                                        mandala);
+  g_signal_handlers_disconnect_by_func (guide,
+                                        gimp_mandala_guide_position_cb,
+                                        mandala);
+
+  gimp_image_remove_guide (image, guide, FALSE);
+  g_object_unref (guide);
+
+  if (orientation == GIMP_ORIENTATION_HORIZONTAL)
+    mandala->horizontal_guide = NULL;
+  else
+    mandala->vertical_guide = NULL;
+}
+
+static void
+gimp_mandala_guide_removed_cb (GObject     *object,
+                               GimpMandala *mandala)
+{
+  GimpSymmetry *sym = GIMP_SYMMETRY (mandala);
+
+  g_signal_handlers_disconnect_by_func (object,
+                                        gimp_mandala_guide_removed_cb,
+                                        mandala);
+  g_signal_handlers_disconnect_by_func (object,
+                                        gimp_mandala_guide_position_cb,
+                                        mandala);
+
+  if (GIMP_GUIDE (object) == mandala->horizontal_guide)
+    {
+      g_object_unref (mandala->horizontal_guide);
+
+      mandala->horizontal_guide = NULL;
+      mandala->center_y         = 0.0;
+
+      gimp_mandala_remove_guide (mandala, GIMP_ORIENTATION_VERTICAL);
+    }
+  else if (GIMP_GUIDE (object) == mandala->vertical_guide)
+    {
+      g_object_unref (mandala->vertical_guide);
+      mandala->vertical_guide = NULL;
+      mandala->center_x       = 0.0;
+
+      gimp_mandala_remove_guide (mandala, GIMP_ORIENTATION_HORIZONTAL);
+    }
+
+  gimp_image_symmetry_remove (sym->image, sym);
+}
+
+static void
+gimp_mandala_guide_position_cb (GObject     *object,
+                                GParamSpec  *pspec,
+                                GimpMandala *mandala)
+{
+  GimpGuide *guide = GIMP_GUIDE (object);
+
+  if (guide == mandala->horizontal_guide)
+    {
+      g_object_set (G_OBJECT (mandala),
+                    "center-y", (gdouble) gimp_guide_get_position (guide),
+                    NULL);
+    }
+  else if (guide == mandala->vertical_guide)
+    {
+      g_object_set (G_OBJECT (mandala),
+                    "center-x", (gdouble) gimp_guide_get_position (guide),
+                    NULL);
+    }
+}
+
+static void
+gimp_mandala_update_strokes (GimpSymmetry *sym,
+                             GimpDrawable *drawable,
+                             GimpCoords   *origin)
+{
+  GimpMandala *mandala = GIMP_MANDALA (sym);
+  GimpCoords  *coords;
+  GimpMatrix3  matrix;
+  gdouble      slice_angle;
+  gdouble      mid_slice_angle = 0.0;
+  gdouble      center_x, center_y;
+  gint         offset_x, offset_y;
+  gint         i;
+
+  gimp_item_get_offset (GIMP_ITEM (drawable), &offset_x, &offset_y);
+
+  center_x = mandala->center_x - offset_x;
+  center_y = mandala->center_y - offset_y;
+
+  g_list_free_full (sym->strokes, g_free);
+  sym->strokes = NULL;
+
+  coords = g_memdup (sym->origin, sizeof (GimpCoords));
+  sym->strokes = g_list_prepend (sym->strokes, coords);
+
+  /* The angle of each slice, in radians. */
+  slice_angle = 2.0 * G_PI / mandala->size;
+
+  if (mandala->enable_reflection)
+    {
+      /* Find out in which slice the user is currently drawing. */
+      gdouble angle = atan2 (sym->origin->y - center_y,
+                             sym->origin->x - center_x);
+      gint slice_no = (int) floor(angle/slice_angle);
+
+      /* Angle where the middle of that slice is. */
+      mid_slice_angle = slice_no * slice_angle + slice_angle / 2.0;
+    }
+
+  for (i = 1; i < mandala->size; i++)
+    {
+      gdouble new_x, new_y;
+
+      coords = g_memdup (sym->origin, sizeof (GimpCoords));
+      gimp_matrix3_identity (&matrix);
+      gimp_matrix3_translate (&matrix,
+                              -center_x,
+                              -center_y);
+      if (mandala->enable_reflection && i % 2 == 1)
+        {
+          /* Reflecting over the mid_slice_angle axis, reflects slice without changing position. */
+          gimp_matrix3_rotate(&matrix, -mid_slice_angle);
+          gimp_matrix3_scale (&matrix, 1, -1);
+          gimp_matrix3_rotate(&matrix, mid_slice_angle - i * slice_angle);
+        }
+      else
+        {
+          gimp_matrix3_rotate (&matrix, - i * slice_angle);
+        }
+      gimp_matrix3_translate (&matrix,
+                              +center_x,
+                              +center_y);
+      gimp_matrix3_transform_point (&matrix,
+                                    coords->x,
+                                    coords->y,
+                                    &new_x,
+                                    &new_y);
+      coords->x = new_x;
+      coords->y = new_y;
+      sym->strokes = g_list_prepend (sym->strokes, coords);
+    }
+
+  sym->strokes = g_list_reverse (sym->strokes);
+
+  g_signal_emit_by_name (sym, "strokes-updated", sym->image);
+}
+
+static void
+gimp_mandala_get_transform (GimpSymmetry *sym,
+                            gint          stroke,
+                            gdouble      *angle,
+                            gboolean     *reflect)
+{
+  GimpMandala *mandala = GIMP_MANDALA (sym);
+  gdouble     slice_angle;
+
+  if (mandala->disable_transformation)
+    return;
+
+  slice_angle = 360.0 / mandala->size;
+
+  if (mandala->enable_reflection && stroke % 2 == 1)
+    {
+      /* Find out in which slice the user is currently drawing. */
+      gdouble origin_angle = gimp_rad_to_deg (atan2 (sym->origin->y - mandala->center_y,
+                                                     sym->origin->x - mandala->center_x));
+      gint slice_no = (int) floor(origin_angle/slice_angle);
+
+      /* Angle where the middle of that slice is. */
+      gdouble mid_slice_angle = slice_no * slice_angle + slice_angle / 2.0;
+
+      *angle = 180.0 - (-2 * mid_slice_angle + stroke * slice_angle) ;
+      *reflect = TRUE;
+    }
+  else
+    {
+      *angle = stroke * slice_angle;
+    }
+}
+
+static void
+gimp_mandala_image_size_changed_cb (GimpImage    *image,
+                                    gint          previous_origin_x,
+                                    gint          previous_origin_y,
+                                    gint          previous_width,
+                                    gint          previous_height,
+                                    GimpSymmetry *sym)
+{
+  if (previous_width != gimp_image_get_width (image) ||
+      previous_height != gimp_image_get_height (image))
+    {
+      g_signal_emit_by_name (sym, "gui-param-changed", sym->image);
+    }
+}
diff --git a/app/core/gimpsymmetry-mandala.h b/app/core/gimpsymmetry-mandala.h
new file mode 100644
index 0000000..0978a40
--- /dev/null
+++ b/app/core/gimpsymmetry-mandala.h
@@ -0,0 +1,61 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpsymmetry-mandala.h
+ * Copyright (C) 2015 Jehan <jehan@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_MANDALA_H__
+#define __GIMP_MANDALA_H__
+
+
+#include "gimpsymmetry.h"
+
+
+#define GIMP_TYPE_MANDALA            (gimp_mandala_get_type ())
+#define GIMP_MANDALA(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_MANDALA, GimpMandala))
+#define GIMP_MANDALA_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_MANDALA, GimpMandalaClass))
+#define GIMP_IS_MANDALA(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_MANDALA))
+#define GIMP_IS_MANDALA_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_MANDALA))
+#define GIMP_MANDALA_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_MANDALA, GimpMandalaClass))
+
+
+typedef struct _GimpMandalaClass GimpMandalaClass;
+
+struct _GimpMandala
+{
+  GimpSymmetry  parent_instance;
+
+  gdouble       center_x;
+  gdouble       center_y;
+  gint          size;
+  gboolean      disable_transformation;
+  gboolean      enable_reflection;
+
+  GimpGuide    *horizontal_guide;
+  GimpGuide    *vertical_guide;
+};
+
+struct _GimpMandalaClass
+{
+  GimpSymmetryClass  parent_class;
+};
+
+
+GType   gimp_mandala_get_type (void) G_GNUC_CONST;
+
+
+#endif  /*  __GIMP_MANDALA_H__  */
diff --git a/app/core/gimpsymmetry-mirror.c b/app/core/gimpsymmetry-mirror.c
new file mode 100644
index 0000000..66a0eaa
--- /dev/null
+++ b/app/core/gimpsymmetry-mirror.c
@@ -0,0 +1,738 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpsymmetry-mirror.c
+ * Copyright (C) 2015 Jehan <jehan@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <cairo.h>
+#include <gegl.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "libgimpconfig/gimpconfig.h"
+
+#include "core-types.h"
+
+#include "gimp.h"
+#include "gimp-cairo.h"
+#include "gimpbrush.h"
+#include "gimpguide.h"
+#include "gimpimage.h"
+#include "gimpimage-guides.h"
+#include "gimpimage-symmetry.h"
+#include "gimpitem.h"
+#include "gimpsymmetry-mirror.h"
+
+#include "gimp-intl.h"
+
+
+enum
+{
+  PROP_0,
+  PROP_HORIZONTAL_SYMMETRY,
+  PROP_VERTICAL_SYMMETRY,
+  PROP_POINT_SYMMETRY,
+  PROP_DISABLE_TRANSFORMATION,
+  PROP_MIRROR_POSITION_X,
+  PROP_MIRROR_POSITION_Y
+};
+
+
+/* Local function prototypes */
+
+static void       gimp_mirror_constructed             (GObject             *object);
+static void       gimp_mirror_finalize                (GObject             *object);
+static void       gimp_mirror_set_property            (GObject             *object,
+                                                       guint                property_id,
+                                                       const GValue        *value,
+                                                       GParamSpec          *pspec);
+static void       gimp_mirror_get_property            (GObject             *object,
+                                                       guint                property_id,
+                                                       GValue              *value,
+                                                       GParamSpec          *pspec);
+
+static void       gimp_mirror_update_strokes          (GimpSymmetry        *mirror,
+                                                       GimpDrawable        *drawable,
+                                                       GimpCoords          *origin);
+static void       gimp_mirror_get_transform           (GimpSymmetry        *mirror,
+                                                       gint                 stroke,
+                                                       gdouble             *angle,
+                                                       gboolean            *reflect);
+static void       gimp_mirror_reset                   (GimpMirror          *mirror);
+static void       gimp_mirror_add_guide               (GimpMirror          *mirror,
+                                                       GimpOrientationType  orientation);
+static void       gimp_mirror_remove_guide            (GimpMirror          *mirror,
+                                                       GimpOrientationType  orientation);
+static void       gimp_mirror_guide_removed_cb        (GObject             *object,
+                                                       GimpMirror          *mirror);
+static void       gimp_mirror_guide_position_cb       (GObject             *object,
+                                                       GParamSpec          *pspec,
+                                                       GimpMirror          *mirror);
+static void       gimp_mirror_active_changed          (GimpSymmetry        *sym);
+static void       gimp_mirror_set_horizontal_symmetry (GimpMirror          *mirror,
+                                                       gboolean             active);
+static void       gimp_mirror_set_vertical_symmetry   (GimpMirror          *mirror,
+                                                       gboolean             active);
+static void       gimp_mirror_set_point_symmetry      (GimpMirror          *mirror,
+                                                       gboolean             active);
+
+static void       gimp_mirror_image_size_changed_cb   (GimpImage           *image,
+                                                       gint                 previous_origin_x,
+                                                       gint                 previous_origin_y,
+                                                       gint                 previous_width,
+                                                       gint                 previous_height,
+                                                       GimpSymmetry        *sym);
+
+G_DEFINE_TYPE (GimpMirror, gimp_mirror, GIMP_TYPE_SYMMETRY)
+
+#define parent_class gimp_mirror_parent_class
+
+
+static void
+gimp_mirror_class_init (GimpMirrorClass *klass)
+{
+  GObjectClass      *object_class   = G_OBJECT_CLASS (klass);
+  GimpSymmetryClass *symmetry_class = GIMP_SYMMETRY_CLASS (klass);
+  GParamSpec        *pspec;
+
+  object_class->constructed         = gimp_mirror_constructed;
+  object_class->finalize            = gimp_mirror_finalize;
+  object_class->set_property        = gimp_mirror_set_property;
+  object_class->get_property        = gimp_mirror_get_property;
+
+  symmetry_class->label             = _("Mirror");
+  symmetry_class->update_strokes    = gimp_mirror_update_strokes;
+  symmetry_class->get_transform     = gimp_mirror_get_transform;
+  symmetry_class->active_changed    = gimp_mirror_active_changed;
+
+  GIMP_CONFIG_PROP_BOOLEAN (object_class, PROP_HORIZONTAL_SYMMETRY,
+                            "horizontal-symmetry",
+                            _("Horizontal Symmetry"),
+                            _("Reflect the initial stroke across a horizontal axis"),
+                            FALSE,
+                            GIMP_PARAM_STATIC_STRINGS |
+                            GIMP_SYMMETRY_PARAM_GUI);
+
+  GIMP_CONFIG_PROP_BOOLEAN (object_class, PROP_VERTICAL_SYMMETRY,
+                            "vertical-symmetry",
+                            _("Vertical Symmetry"),
+                            _("Reflect the initial stroke across a vertical axis"),
+                            FALSE,
+                            GIMP_PARAM_STATIC_STRINGS |
+                            GIMP_SYMMETRY_PARAM_GUI);
+
+  GIMP_CONFIG_PROP_BOOLEAN (object_class, PROP_POINT_SYMMETRY,
+                            "point-symmetry",
+                            _("Central Symmetry"),
+                            _("Invert the initial stroke through a point"),
+                            FALSE,
+                            GIMP_PARAM_STATIC_STRINGS |
+                            GIMP_SYMMETRY_PARAM_GUI);
+
+  GIMP_CONFIG_PROP_BOOLEAN (object_class, PROP_DISABLE_TRANSFORMATION,
+                            "disable-transformation",
+                            _("Disable brush transform"),
+                            _("Disable brush reflection"),
+                            FALSE,
+                            GIMP_PARAM_STATIC_STRINGS |
+                            GIMP_SYMMETRY_PARAM_GUI);
+
+  GIMP_CONFIG_PROP_DOUBLE (object_class, PROP_MIRROR_POSITION_X,
+                           "mirror-position-x",
+                           _("Vertical axis position"),
+                           NULL,
+                           0.0, G_MAXDOUBLE, 0.0,
+                           GIMP_PARAM_STATIC_STRINGS |
+                           GIMP_SYMMETRY_PARAM_GUI);
+
+  pspec = g_object_class_find_property (object_class, "mirror-position-x");
+  gegl_param_spec_set_property_key (pspec, "unit", "pixel-coordinate");
+  gegl_param_spec_set_property_key (pspec, "axis", "x");
+
+  GIMP_CONFIG_PROP_DOUBLE (object_class, PROP_MIRROR_POSITION_Y,
+                           "mirror-position-y",
+                           _("Horizontal axis position"),
+                           NULL,
+                           0.0, G_MAXDOUBLE, 0.0,
+                           GIMP_PARAM_STATIC_STRINGS |
+                           GIMP_SYMMETRY_PARAM_GUI);
+
+  pspec = g_object_class_find_property (object_class, "mirror-position-y");
+  gegl_param_spec_set_property_key (pspec, "unit", "pixel-coordinate");
+  gegl_param_spec_set_property_key (pspec, "axis", "y");
+}
+
+static void
+gimp_mirror_init (GimpMirror *mirror)
+{
+}
+
+static void
+gimp_mirror_constructed (GObject *object)
+{
+  GimpSymmetry *sym = GIMP_SYMMETRY (object);
+
+  g_signal_connect_object (sym->image, "size-changed-detailed",
+                           G_CALLBACK (gimp_mirror_image_size_changed_cb),
+                           sym, 0);
+}
+
+static void
+gimp_mirror_finalize (GObject *object)
+{
+  GimpMirror *mirror = GIMP_MIRROR (object);
+
+  g_clear_object (&mirror->horizontal_guide);
+  g_clear_object (&mirror->vertical_guide);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gimp_mirror_set_property (GObject      *object,
+                          guint         property_id,
+                          const GValue *value,
+                          GParamSpec   *pspec)
+{
+  GimpMirror *mirror = GIMP_MIRROR (object);
+  GimpImage  *image  = GIMP_SYMMETRY (mirror)->image;
+
+  switch (property_id)
+    {
+    case PROP_HORIZONTAL_SYMMETRY:
+      gimp_mirror_set_horizontal_symmetry (mirror,
+                                           g_value_get_boolean (value));
+      break;
+
+    case PROP_VERTICAL_SYMMETRY:
+      gimp_mirror_set_vertical_symmetry (mirror,
+                                         g_value_get_boolean (value));
+      break;
+
+    case PROP_POINT_SYMMETRY:
+      gimp_mirror_set_point_symmetry (mirror,
+                                      g_value_get_boolean (value));
+      break;
+
+    case PROP_DISABLE_TRANSFORMATION:
+      mirror->disable_transformation = g_value_get_boolean (value);
+      break;
+
+    case PROP_MIRROR_POSITION_X:
+      if (g_value_get_double (value) >= 0.0 &&
+          g_value_get_double (value) < (gdouble) gimp_image_get_width (image))
+        {
+          mirror->mirror_position_x = g_value_get_double (value);
+
+          if (mirror->vertical_guide)
+            {
+              g_signal_handlers_block_by_func (mirror->vertical_guide,
+                                               gimp_mirror_guide_position_cb,
+                                               mirror);
+              gimp_image_move_guide (image, mirror->vertical_guide,
+                                     mirror->mirror_position_x,
+                                     FALSE);
+              g_signal_handlers_unblock_by_func (mirror->vertical_guide,
+                                                 gimp_mirror_guide_position_cb,
+                                                 mirror);
+            }
+        }
+      break;
+
+    case PROP_MIRROR_POSITION_Y:
+      if (g_value_get_double (value) >= 0.0 &&
+          g_value_get_double (value) < (gdouble) gimp_image_get_height (image))
+        {
+          mirror->mirror_position_y = g_value_get_double (value);
+
+          if (mirror->horizontal_guide)
+            {
+              g_signal_handlers_block_by_func (mirror->horizontal_guide,
+                                               gimp_mirror_guide_position_cb,
+                                               mirror);
+              gimp_image_move_guide (image, mirror->horizontal_guide,
+                                     mirror->mirror_position_y,
+                                     FALSE);
+              g_signal_handlers_unblock_by_func (mirror->horizontal_guide,
+                                                 gimp_mirror_guide_position_cb,
+                                                 mirror);
+            }
+        }
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_mirror_get_property (GObject    *object,
+                          guint       property_id,
+                          GValue     *value,
+                          GParamSpec *pspec)
+{
+  GimpMirror *mirror = GIMP_MIRROR (object);
+
+  switch (property_id)
+    {
+    case PROP_HORIZONTAL_SYMMETRY:
+      g_value_set_boolean (value, mirror->horizontal_mirror);
+      break;
+    case PROP_VERTICAL_SYMMETRY:
+      g_value_set_boolean (value, mirror->vertical_mirror);
+      break;
+    case PROP_POINT_SYMMETRY:
+      g_value_set_boolean (value, mirror->point_symmetry);
+      break;
+    case PROP_DISABLE_TRANSFORMATION:
+      g_value_set_boolean (value, mirror->disable_transformation);
+      break;
+    case PROP_MIRROR_POSITION_X:
+      g_value_set_double (value, mirror->mirror_position_x);
+      break;
+    case PROP_MIRROR_POSITION_Y:
+      g_value_set_double (value, mirror->mirror_position_y);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_mirror_update_strokes (GimpSymmetry *sym,
+                            GimpDrawable *drawable,
+                            GimpCoords   *origin)
+{
+  GimpMirror *mirror  = GIMP_MIRROR (sym);
+  GList      *strokes = NULL;
+  GimpCoords *coords;
+  gdouble     mirror_position_x, mirror_position_y;
+  gint        offset_x,          offset_y;
+
+  gimp_item_get_offset (GIMP_ITEM (drawable), &offset_x, &offset_y);
+
+  mirror_position_x = mirror->mirror_position_x - offset_x;
+  mirror_position_y = mirror->mirror_position_y - offset_y;
+
+  g_list_free_full (sym->strokes, g_free);
+  strokes = g_list_prepend (strokes,
+                            g_memdup (origin, sizeof (GimpCoords)));
+
+  if (mirror->horizontal_mirror)
+    {
+      coords = g_memdup (origin, sizeof (GimpCoords));
+      coords->y = 2.0 * mirror_position_y - origin->y;
+      strokes = g_list_prepend (strokes, coords);
+    }
+
+  if (mirror->vertical_mirror)
+    {
+      coords = g_memdup (origin, sizeof (GimpCoords));
+      coords->x = 2.0 * mirror_position_x - origin->x;
+      strokes = g_list_prepend (strokes, coords);
+    }
+
+  if (mirror->point_symmetry)
+    {
+      coords = g_memdup (origin, sizeof (GimpCoords));
+      coords->x = 2.0 * mirror_position_x - origin->x;
+      coords->y = 2.0 * mirror_position_y - origin->y;
+      strokes = g_list_prepend (strokes, coords);
+    }
+
+  sym->strokes = g_list_reverse (strokes);
+
+  g_signal_emit_by_name (sym, "strokes-updated", sym->image);
+}
+
+static void
+gimp_mirror_get_transform (GimpSymmetry *sym,
+                           gint          stroke,
+                           gdouble      *angle,
+                           gboolean     *reflect)
+{
+  GimpMirror *mirror = GIMP_MIRROR (sym);
+
+  if (mirror->disable_transformation)
+    return;
+
+  if (! mirror->horizontal_mirror && stroke >= 1)
+    stroke++;
+
+  if (! mirror->vertical_mirror && stroke >= 2)
+    stroke++;
+
+  switch (stroke)
+    {
+    /* original */
+    case 0:
+      break;
+
+    /* horizontal */
+    case 1:
+      *angle   = 180.0;
+      *reflect = TRUE;
+      break;
+
+    /* vertical */
+    case 2:
+      *reflect = TRUE;
+      break;
+
+    /* central */
+    case 3:
+      *angle   = 180.0;
+      break;
+
+    default:
+      g_return_if_reached ();
+    }
+}
+
+static void
+gimp_mirror_reset (GimpMirror *mirror)
+{
+  GimpSymmetry *sym = GIMP_SYMMETRY (mirror);
+
+  if (sym->origin)
+    {
+      gimp_symmetry_set_origin (sym, sym->drawable,
+                                sym->origin);
+    }
+}
+
+static void
+gimp_mirror_add_guide (GimpMirror          *mirror,
+                       GimpOrientationType  orientation)
+{
+  GimpSymmetry *sym = GIMP_SYMMETRY (mirror);
+  GimpImage    *image;
+  Gimp         *gimp;
+  GimpGuide    *guide;
+  gdouble       position;
+
+  image = sym->image;
+  gimp  = image->gimp;
+
+  guide = gimp_guide_custom_new (orientation,
+                                 gimp->next_guide_ID++,
+                                 GIMP_GUIDE_STYLE_MIRROR);
+
+  if (orientation == GIMP_ORIENTATION_HORIZONTAL)
+    {
+      /* Mirror guide position at first activation is at canvas middle. */
+      if (mirror->mirror_position_y < 1.0)
+        position = gimp_image_get_height (image) / 2.0;
+      else
+        position = mirror->mirror_position_y;
+
+      g_object_set (mirror,
+                    "mirror-position-y", position,
+                    NULL);
+
+      mirror->horizontal_guide = guide;
+    }
+  else
+    {
+      /* Mirror guide position at first activation is at canvas middle. */
+      if (mirror->mirror_position_x < 1.0)
+        position = gimp_image_get_width (image) / 2.0;
+      else
+        position = mirror->mirror_position_x;
+
+      g_object_set (mirror,
+                    "mirror-position-x", position,
+                    NULL);
+
+      mirror->vertical_guide = guide;
+    }
+
+  g_signal_connect (guide, "removed",
+                    G_CALLBACK (gimp_mirror_guide_removed_cb),
+                    mirror);
+
+  gimp_image_add_guide (image, guide, (gint) position);
+
+  g_signal_connect (guide, "notify::position",
+                    G_CALLBACK (gimp_mirror_guide_position_cb),
+                    mirror);
+}
+
+static void
+gimp_mirror_remove_guide (GimpMirror          *mirror,
+                          GimpOrientationType  orientation)
+{
+  GimpSymmetry *sym = GIMP_SYMMETRY (mirror);
+  GimpImage    *image;
+  GimpGuide    *guide;
+
+  image = sym->image;
+  guide = (orientation == GIMP_ORIENTATION_HORIZONTAL) ?
+    mirror->horizontal_guide : mirror->vertical_guide;
+
+  /* The guide may have already been removed, for instance from GUI. */
+  if (guide)
+    {
+      g_signal_handlers_disconnect_by_func (G_OBJECT (guide),
+                                            gimp_mirror_guide_removed_cb,
+                                            mirror);
+      g_signal_handlers_disconnect_by_func (G_OBJECT (guide),
+                                            gimp_mirror_guide_position_cb,
+                                            mirror);
+
+      gimp_image_remove_guide (image, guide, FALSE);
+      g_object_unref (guide);
+
+      if (orientation == GIMP_ORIENTATION_HORIZONTAL)
+        mirror->horizontal_guide = NULL;
+      else
+        mirror->vertical_guide = NULL;
+    }
+}
+
+static void
+gimp_mirror_guide_removed_cb (GObject    *object,
+                              GimpMirror *mirror)
+{
+  GimpSymmetry *symmetry = GIMP_SYMMETRY (mirror);
+
+  g_signal_handlers_disconnect_by_func (object,
+                                        gimp_mirror_guide_removed_cb,
+                                        mirror);
+  g_signal_handlers_disconnect_by_func (object,
+                                        gimp_mirror_guide_position_cb,
+                                        mirror);
+
+  if (GIMP_GUIDE (object) == mirror->horizontal_guide)
+    {
+      g_object_unref (mirror->horizontal_guide);
+      mirror->horizontal_guide    = NULL;
+
+      g_object_set (mirror,
+                    "horizontal-symmetry", FALSE,
+                    NULL);
+      g_object_set (mirror,
+                    "point-symmetry", FALSE,
+                    NULL);
+      g_object_set (mirror,
+                    "mirror-position-y", 0.0,
+                    NULL);
+
+      if (mirror->vertical_guide &&
+          ! mirror->vertical_mirror)
+        {
+          g_signal_handlers_disconnect_by_func (G_OBJECT (mirror->vertical_guide),
+                                                gimp_mirror_guide_removed_cb,
+                                                mirror);
+          g_signal_handlers_disconnect_by_func (G_OBJECT (mirror->vertical_guide),
+                                                gimp_mirror_guide_position_cb,
+                                                mirror);
+
+          gimp_image_remove_guide (symmetry->image,
+                                   mirror->vertical_guide,
+                                   FALSE);
+          g_clear_object (&mirror->vertical_guide);
+        }
+    }
+  else if (GIMP_GUIDE (object) == mirror->vertical_guide)
+    {
+      g_object_unref (mirror->vertical_guide);
+      mirror->vertical_guide    = NULL;
+
+      g_object_set (mirror,
+                    "vertical-symmetry", FALSE,
+                    NULL);
+      g_object_set (mirror,
+                    "point-symmetry", FALSE,
+                    NULL);
+      g_object_set (mirror,
+                    "mirror-position-x", 0.0,
+                    NULL);
+
+      if (mirror->horizontal_guide &&
+          ! mirror->horizontal_mirror)
+        {
+          g_signal_handlers_disconnect_by_func (G_OBJECT (mirror->horizontal_guide),
+                                                gimp_mirror_guide_removed_cb,
+                                                mirror);
+          g_signal_handlers_disconnect_by_func (G_OBJECT (mirror->horizontal_guide),
+                                                gimp_mirror_guide_position_cb,
+                                                mirror);
+
+          gimp_image_remove_guide (symmetry->image,
+                                   mirror->horizontal_guide,
+                                   FALSE);
+          g_clear_object (&mirror->horizontal_guide);
+        }
+    }
+
+  if (mirror->horizontal_guide == NULL &&
+      mirror->vertical_guide   == NULL)
+    {
+      gimp_image_symmetry_remove (symmetry->image,
+                                  GIMP_SYMMETRY (mirror));
+    }
+  else
+    {
+      gimp_mirror_reset (mirror);
+      g_signal_emit_by_name (mirror, "gui-param-changed",
+                             GIMP_SYMMETRY (mirror)->image);
+    }
+}
+
+static void
+gimp_mirror_guide_position_cb (GObject    *object,
+                               GParamSpec *pspec,
+                               GimpMirror *mirror)
+{
+  GimpGuide *guide = GIMP_GUIDE (object);
+
+  if (guide == mirror->horizontal_guide)
+    {
+      g_object_set (mirror,
+                    "mirror-position-y", (gdouble) gimp_guide_get_position (guide),
+                    NULL);
+    }
+  else if (guide == mirror->vertical_guide)
+    {
+      g_object_set (mirror,
+                    "mirror-position-x", (gdouble) gimp_guide_get_position (guide),
+                    NULL);
+    }
+}
+
+static void
+gimp_mirror_active_changed (GimpSymmetry *sym)
+{
+  GimpMirror *mirror = GIMP_MIRROR (sym);
+
+  if (sym->active)
+    {
+      if ((mirror->horizontal_mirror || mirror->point_symmetry) &&
+          ! mirror->horizontal_guide)
+        gimp_mirror_add_guide (mirror, GIMP_ORIENTATION_HORIZONTAL);
+
+      if ((mirror->vertical_mirror || mirror->point_symmetry) &&
+          ! mirror->vertical_guide)
+        gimp_mirror_add_guide (mirror, GIMP_ORIENTATION_VERTICAL);
+    }
+  else
+    {
+      if (mirror->horizontal_guide)
+        gimp_mirror_remove_guide (mirror, GIMP_ORIENTATION_HORIZONTAL);
+
+      if (mirror->vertical_guide)
+        gimp_mirror_remove_guide (mirror, GIMP_ORIENTATION_VERTICAL);
+    }
+}
+
+static void
+gimp_mirror_set_horizontal_symmetry (GimpMirror *mirror,
+                                     gboolean    active)
+{
+  if (active == mirror->horizontal_mirror)
+    return;
+
+  mirror->horizontal_mirror = active;
+
+  if (active)
+    {
+      if (! mirror->horizontal_guide)
+        gimp_mirror_add_guide (mirror, GIMP_ORIENTATION_HORIZONTAL);
+    }
+  else if (! mirror->point_symmetry)
+    {
+      gimp_mirror_remove_guide (mirror, GIMP_ORIENTATION_HORIZONTAL);
+    }
+
+  gimp_mirror_reset (mirror);
+}
+
+static void
+gimp_mirror_set_vertical_symmetry (GimpMirror *mirror,
+                                   gboolean    active)
+{
+  if (active == mirror->vertical_mirror)
+    return;
+
+  mirror->vertical_mirror = active;
+
+  if (active)
+    {
+      if (! mirror->vertical_guide)
+        gimp_mirror_add_guide (mirror, GIMP_ORIENTATION_VERTICAL);
+    }
+  else if (! mirror->point_symmetry)
+    {
+      gimp_mirror_remove_guide (mirror, GIMP_ORIENTATION_VERTICAL);
+    }
+
+  gimp_mirror_reset (mirror);
+}
+
+static void
+gimp_mirror_set_point_symmetry (GimpMirror *mirror,
+                                gboolean    active)
+{
+  if (active == mirror->point_symmetry)
+    return;
+
+  mirror->point_symmetry = active;
+
+  if (active)
+    {
+      /* Show the horizontal guide unless already shown */
+      if (! mirror->horizontal_guide)
+        gimp_mirror_add_guide (mirror, GIMP_ORIENTATION_HORIZONTAL);
+
+      /* Show the vertical guide unless already shown */
+      if (! mirror->vertical_guide)
+        gimp_mirror_add_guide (mirror, GIMP_ORIENTATION_VERTICAL);
+    }
+  else
+    {
+      /* Remove the horizontal guide unless needed by horizontal mirror */
+      if (! mirror->horizontal_mirror)
+        gimp_mirror_remove_guide (mirror, GIMP_ORIENTATION_HORIZONTAL);
+
+      /* Remove the vertical guide unless needed by vertical mirror */
+      if (! mirror->vertical_mirror)
+        gimp_mirror_remove_guide (mirror, GIMP_ORIENTATION_VERTICAL);
+    }
+
+  gimp_mirror_reset (mirror);
+}
+
+static void
+gimp_mirror_image_size_changed_cb (GimpImage    *image,
+                                   gint          previous_origin_x,
+                                   gint          previous_origin_y,
+                                   gint          previous_width,
+                                   gint          previous_height,
+                                   GimpSymmetry *sym)
+{
+  if (previous_width != gimp_image_get_width (image) ||
+      previous_height != gimp_image_get_height (image))
+    {
+      g_signal_emit_by_name (sym, "gui-param-changed", sym->image);
+    }
+}
diff --git a/app/core/gimpsymmetry-mirror.h b/app/core/gimpsymmetry-mirror.h
new file mode 100644
index 0000000..f9ac26a
--- /dev/null
+++ b/app/core/gimpsymmetry-mirror.h
@@ -0,0 +1,62 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpsymmetry-mirror.h
+ * Copyright (C) 2015 Jehan <jehan@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_MIRROR_H__
+#define __GIMP_MIRROR_H__
+
+
+#include "gimpsymmetry.h"
+
+
+#define GIMP_TYPE_MIRROR            (gimp_mirror_get_type ())
+#define GIMP_MIRROR(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_MIRROR, GimpMirror))
+#define GIMP_MIRROR_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_MIRROR, GimpMirrorClass))
+#define GIMP_IS_MIRROR(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_MIRROR))
+#define GIMP_IS_MIRROR_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_MIRROR))
+#define GIMP_MIRROR_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_MIRROR, GimpMirrorClass))
+
+
+typedef struct _GimpMirrorClass GimpMirrorClass;
+
+struct _GimpMirror
+{
+  GimpSymmetry  parent_instance;
+
+  gboolean      horizontal_mirror;
+  gboolean      vertical_mirror;
+  gboolean      point_symmetry;
+  gboolean      disable_transformation;
+
+  gdouble       mirror_position_y;
+  gdouble       mirror_position_x;
+  GimpGuide    *horizontal_guide;
+  GimpGuide    *vertical_guide;
+};
+
+struct _GimpMirrorClass
+{
+  GimpSymmetryClass  parent_class;
+};
+
+
+GType   gimp_mirror_get_type (void) G_GNUC_CONST;
+
+
+#endif  /*  __GIMP_MIRROR_H__  */
diff --git a/app/core/gimpsymmetry-tiling.c b/app/core/gimpsymmetry-tiling.c
new file mode 100644
index 0000000..555f584
--- /dev/null
+++ b/app/core/gimpsymmetry-tiling.c
@@ -0,0 +1,442 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpsymmetry-tiling.c
+ * Copyright (C) 2015 Jehan <jehan@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <math.h>
+#include <string.h>
+
+#include <gegl.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "libgimpconfig/gimpconfig.h"
+
+#include "core-types.h"
+
+#include "gimp.h"
+#include "gimpdrawable.h"
+#include "gimpimage.h"
+#include "gimpitem.h"
+#include "gimpsymmetry-tiling.h"
+
+#include "gimp-intl.h"
+
+
+/* Using same epsilon as in GLIB. */
+#define G_DOUBLE_EPSILON        (1e-90)
+
+enum
+{
+  PROP_0,
+
+  PROP_INTERVAL_X,
+  PROP_INTERVAL_Y,
+  PROP_SHIFT,
+  PROP_MAX_X,
+  PROP_MAX_Y
+};
+
+
+/* Local function prototypes */
+
+static void       gimp_tiling_constructed        (GObject      *object);
+static void       gimp_tiling_finalize           (GObject      *object);
+static void       gimp_tiling_set_property       (GObject      *object,
+                                                  guint         property_id,
+                                                  const GValue *value,
+                                                  GParamSpec   *pspec);
+static void       gimp_tiling_get_property       (GObject      *object,
+                                                  guint         property_id,
+                                                  GValue       *value,
+                                                  GParamSpec   *pspec);
+
+static void       gimp_tiling_update_strokes     (GimpSymmetry *tiling,
+                                                  GimpDrawable *drawable,
+                                                  GimpCoords   *origin);
+static void    gimp_tiling_image_size_changed_cb (GimpImage    *image,
+                                                  gint          previous_origin_x,
+                                                  gint          previous_origin_y,
+                                                  gint          previous_width,
+                                                  gint          previous_height,
+                                                  GimpSymmetry *sym);
+
+
+G_DEFINE_TYPE (GimpTiling, gimp_tiling, GIMP_TYPE_SYMMETRY)
+
+#define parent_class gimp_tiling_parent_class
+
+
+static void
+gimp_tiling_class_init (GimpTilingClass *klass)
+{
+  GObjectClass      *object_class   = G_OBJECT_CLASS (klass);
+  GimpSymmetryClass *symmetry_class = GIMP_SYMMETRY_CLASS (klass);
+  GParamSpec        *pspec;
+
+  object_class->constructed       = gimp_tiling_constructed;
+  object_class->finalize          = gimp_tiling_finalize;
+  object_class->set_property      = gimp_tiling_set_property;
+  object_class->get_property      = gimp_tiling_get_property;
+
+  symmetry_class->label           = _("Tiling");
+  symmetry_class->update_strokes  = gimp_tiling_update_strokes;
+
+  GIMP_CONFIG_PROP_DOUBLE (object_class, PROP_INTERVAL_X,
+                           "interval-x",
+                           _("Interval X"),
+                           _("Interval on the X axis (pixels)"),
+                           0.0, G_MAXDOUBLE, 0.0,
+                           GIMP_PARAM_STATIC_STRINGS |
+                           GIMP_SYMMETRY_PARAM_GUI);
+
+  pspec = g_object_class_find_property (object_class, "interval-x");
+  gegl_param_spec_set_property_key (pspec, "unit", "pixel-distance");
+  gegl_param_spec_set_property_key (pspec, "axis", "x");
+
+  GIMP_CONFIG_PROP_DOUBLE (object_class, PROP_INTERVAL_Y,
+                           "interval-y",
+                           _("Interval Y"),
+                           _("Interval on the Y axis (pixels)"),
+                           0.0, G_MAXDOUBLE, 0.0,
+                           GIMP_PARAM_STATIC_STRINGS |
+                           GIMP_SYMMETRY_PARAM_GUI);
+
+  pspec = g_object_class_find_property (object_class, "interval-y");
+  gegl_param_spec_set_property_key (pspec, "unit", "pixel-distance");
+  gegl_param_spec_set_property_key (pspec, "axis", "y");
+
+  GIMP_CONFIG_PROP_DOUBLE (object_class, PROP_SHIFT,
+                           "shift",
+                           _("Shift"),
+                           _("X-shift between lines (pixels)"),
+                           0.0, G_MAXDOUBLE, 0.0,
+                           GIMP_PARAM_STATIC_STRINGS |
+                           GIMP_SYMMETRY_PARAM_GUI);
+
+  pspec = g_object_class_find_property (object_class, "shift");
+  gegl_param_spec_set_property_key (pspec, "unit", "pixel-distance");
+  gegl_param_spec_set_property_key (pspec, "axis", "x");
+
+  GIMP_CONFIG_PROP_INT (object_class, PROP_MAX_X,
+                        "max-x",
+                        _("Max strokes X"),
+                        _("Maximum number of strokes on the X axis"),
+                        0, 100, 0,
+                        GIMP_PARAM_STATIC_STRINGS |
+                        GIMP_SYMMETRY_PARAM_GUI);
+
+  GIMP_CONFIG_PROP_INT (object_class, PROP_MAX_Y,
+                        "max-y",
+                        _("Max strokes Y"),
+                        _("Maximum number of strokes on the Y axis"),
+                        0, 100, 0,
+                        GIMP_PARAM_STATIC_STRINGS |
+                        GIMP_SYMMETRY_PARAM_GUI);
+}
+
+static void
+gimp_tiling_init (GimpTiling *tiling)
+{
+}
+
+static void
+gimp_tiling_constructed (GObject *object)
+{
+  GimpSymmetry *sym    = GIMP_SYMMETRY (object);
+  GimpTiling   *tiling = GIMP_TILING (object);
+
+  g_signal_connect_object (sym->image, "size-changed-detailed",
+                           G_CALLBACK (gimp_tiling_image_size_changed_cb),
+                           sym, 0);
+
+  /* Set reasonable defaults. */
+  tiling->interval_x = gimp_image_get_width (sym->image) / 2;
+  tiling->interval_y = gimp_image_get_height (sym->image) / 2;
+}
+
+static void
+gimp_tiling_finalize (GObject *object)
+{
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gimp_tiling_set_property (GObject      *object,
+                          guint         property_id,
+                          const GValue *value,
+                          GParamSpec   *pspec)
+{
+  GimpTiling   *tiling = GIMP_TILING (object);
+  GimpSymmetry *sym    = GIMP_SYMMETRY (tiling);
+
+  switch (property_id)
+    {
+    case PROP_INTERVAL_X:
+      if (sym->image)
+        {
+          gdouble new_x = g_value_get_double (value);
+
+          if (new_x < gimp_image_get_width (sym->image))
+            {
+              tiling->interval_x = new_x;
+
+              if (tiling->interval_x <= tiling->shift + G_DOUBLE_EPSILON)
+                {
+                  GValue val = G_VALUE_INIT;
+
+                  g_value_init (&val, G_TYPE_DOUBLE);
+                  g_value_set_double (&val, 0.0);
+                  g_object_set_property (G_OBJECT (object), "shift", &val);
+                }
+              if (sym->drawable)
+                gimp_tiling_update_strokes (sym, sym->drawable, sym->origin);
+            }
+        }
+      break;
+
+    case PROP_INTERVAL_Y:
+        {
+          gdouble new_y = g_value_get_double (value);
+
+          if (new_y < gimp_image_get_height (sym->image))
+            {
+              tiling->interval_y = new_y;
+
+              if (tiling->interval_y <= G_DOUBLE_EPSILON)
+                {
+                  GValue val = G_VALUE_INIT;
+
+                  g_value_init (&val, G_TYPE_DOUBLE);
+                  g_value_set_double (&val, 0.0);
+                  g_object_set_property (G_OBJECT (object), "shift", &val);
+                }
+              if (sym->drawable)
+                gimp_tiling_update_strokes (sym, sym->drawable, sym->origin);
+            }
+        }
+      break;
+
+    case PROP_SHIFT:
+        {
+          gdouble new_shift = g_value_get_double (value);
+
+          if (new_shift == 0.0 ||
+              (tiling->interval_y != 0.0 && new_shift < tiling->interval_x))
+            {
+              tiling->shift = new_shift;
+              if (sym->drawable)
+                gimp_tiling_update_strokes (sym, sym->drawable, sym->origin);
+            }
+        }
+      break;
+
+    case PROP_MAX_X:
+      tiling->max_x = g_value_get_int (value);
+      if (sym->drawable)
+        gimp_tiling_update_strokes (sym, sym->drawable, sym->origin);
+      break;
+
+    case PROP_MAX_Y:
+      tiling->max_y = g_value_get_int (value);
+      if (sym->drawable)
+        gimp_tiling_update_strokes (sym, sym->drawable, sym->origin);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_tiling_get_property (GObject    *object,
+                          guint       property_id,
+                          GValue     *value,
+                          GParamSpec *pspec)
+{
+  GimpTiling *tiling = GIMP_TILING (object);
+
+  switch (property_id)
+    {
+    case PROP_INTERVAL_X:
+      g_value_set_double (value, tiling->interval_x);
+      break;
+    case PROP_INTERVAL_Y:
+      g_value_set_double (value, tiling->interval_y);
+      break;
+    case PROP_SHIFT:
+      g_value_set_double (value, tiling->shift);
+      break;
+    case PROP_MAX_X:
+      g_value_set_int (value, tiling->max_x);
+      break;
+    case PROP_MAX_Y:
+      g_value_set_int (value, tiling->max_y);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_tiling_update_strokes (GimpSymmetry *sym,
+                            GimpDrawable *drawable,
+                            GimpCoords   *origin)
+{
+  GimpTiling *tiling  = GIMP_TILING (sym);
+  GList      *strokes = NULL;
+  GimpCoords *coords;
+  gdouble     width;
+  gdouble     height;
+  gdouble     startx = origin->x;
+  gdouble     starty = origin->y;
+  gdouble     x;
+  gdouble     y;
+  gint        x_count;
+  gint        y_count;
+
+  g_list_free_full (sym->strokes, g_free);
+  sym->strokes = NULL;
+
+  width  = gimp_item_get_width (GIMP_ITEM (drawable));
+  height = gimp_item_get_height (GIMP_ITEM (drawable));
+
+  if (sym->stateful)
+    {
+      /* While I can compute exactly the right number of strokes to
+       * paint on-canvas for stateless tools, stateful tools need to
+       * always have the same number and order of strokes. For this
+       * reason, I compute strokes to fill 2 times the width and height.
+       * This makes the symmetry less efficient with stateful tools, but
+       * also weird behavior may happen if you decide to paint out of
+       * canvas and expect tiling to work in-canvas since it won't
+       * actually be infinite (as no new strokes can be added while
+       * painting since we are stateful).
+       */
+      gint i, j;
+
+      if (tiling->interval_x < 1.0)
+        {
+          x_count = 1;
+        }
+      else if (tiling->max_x == 0)
+        {
+          x_count = (gint) ceil (width / tiling->interval_x);
+          startx -= tiling->interval_x * (gdouble) x_count;
+          x_count = 2 * x_count + 1;
+        }
+      else
+        {
+          x_count = tiling->max_x;
+        }
+
+      if (tiling->interval_y < 1.0)
+        {
+          y_count = 1;
+        }
+      else if (tiling->max_y == 0)
+        {
+          y_count = (gint) ceil (height / tiling->interval_y);
+          starty -= tiling->interval_y * (gdouble) y_count;
+          y_count = 2 * y_count + 1;
+        }
+      else
+        {
+          y_count = tiling->max_y;
+        }
+
+      for (i = 0, x = startx; i < x_count; i++)
+        {
+          for (j = 0, y = starty; j < y_count; j++)
+            {
+              coords = g_memdup (origin, sizeof (GimpCoords));
+              coords->x = x;
+              coords->y = y;
+              strokes = g_list_prepend (strokes, coords);
+
+              y += tiling->interval_y;
+            }
+          x += tiling->interval_x;
+        }
+    }
+  else
+    {
+      if (origin->x > 0 && tiling->max_x == 0 && tiling->interval_x >= 1.0)
+        startx = fmod (origin->x, tiling->interval_x) - tiling->interval_x;
+
+      if (origin->y > 0 && tiling->max_y == 0 && tiling->interval_y >= 1.0)
+        {
+          starty = fmod (origin->y, tiling->interval_y) - tiling->interval_y;
+
+          if (tiling->shift > 0.0)
+            startx -= tiling->shift * floor (origin->y / tiling->interval_y + 1);
+        }
+
+      for (y_count = 0, y = starty; y < height + tiling->interval_y;
+           y_count++, y += tiling->interval_y)
+        {
+          if (tiling->max_y && y_count >= tiling->max_y)
+            break;
+
+          for (x_count = 0, x = startx; x < width + tiling->interval_x;
+               x_count++, x += tiling->interval_x)
+            {
+              if (tiling->max_x && x_count >= tiling->max_x)
+                break;
+
+              coords = g_memdup (origin, sizeof (GimpCoords));
+              coords->x = x;
+              coords->y = y;
+              strokes = g_list_prepend (strokes, coords);
+
+              if (tiling->interval_x < 1.0)
+                break;
+            }
+
+          if (tiling->max_x || startx + tiling->shift <= 0.0)
+            startx = startx + tiling->shift;
+          else
+            startx = startx - tiling->interval_x + tiling->shift;
+
+          if (tiling->interval_y < 1.0)
+            break;
+        }
+    }
+
+  sym->strokes = strokes;
+
+  g_signal_emit_by_name (sym, "strokes-updated", sym->image);
+}
+
+static void
+gimp_tiling_image_size_changed_cb (GimpImage    *image,
+                                   gint          previous_origin_x,
+                                   gint          previous_origin_y,
+                                   gint          previous_width,
+                                   gint          previous_height,
+                                   GimpSymmetry *sym)
+{
+  if (previous_width  != gimp_image_get_width  (image) ||
+      previous_height != gimp_image_get_height (image))
+    {
+      g_signal_emit_by_name (sym, "gui-param-changed", sym->image);
+    }
+}
diff --git a/app/core/gimpsymmetry-tiling.h b/app/core/gimpsymmetry-tiling.h
new file mode 100644
index 0000000..7fbff71
--- /dev/null
+++ b/app/core/gimpsymmetry-tiling.h
@@ -0,0 +1,58 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpsymmetry-tiling.h
+ * Copyright (C) 2015 Jehan <jehan@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_TILING_H__
+#define __GIMP_TILING_H__
+
+
+#include "gimpsymmetry.h"
+
+
+#define GIMP_TYPE_TILING            (gimp_tiling_get_type ())
+#define GIMP_TILING(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_TILING, GimpTiling))
+#define GIMP_TILING_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_TILING, GimpTilingClass))
+#define GIMP_IS_TILING(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_TILING))
+#define GIMP_IS_TILING_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_TILING))
+#define GIMP_TILING_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_TILING, GimpTilingClass))
+
+
+typedef struct _GimpTilingClass GimpTilingClass;
+
+struct _GimpTiling
+{
+  GimpSymmetry  parent_instance;
+
+  gdouble       interval_x;
+  gdouble       interval_y;
+  gdouble       shift;
+  gint          max_x;
+  gint          max_y;
+};
+
+struct _GimpTilingClass
+{
+  GimpSymmetryClass  parent_class;
+};
+
+
+GType   gimp_tiling_get_type (void) G_GNUC_CONST;
+
+
+#endif  /*  __GIMP_TILING_H__  */
diff --git a/app/core/gimpsymmetry.c b/app/core/gimpsymmetry.c
new file mode 100644
index 0000000..e0bc23b
--- /dev/null
+++ b/app/core/gimpsymmetry.c
@@ -0,0 +1,591 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpsymmetry.c
+ * Copyright (C) 2015 Jehan <jehan@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <gegl.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpconfig/gimpconfig.h"
+#include "libgimpmath/gimpmath.h"
+
+#include "core-types.h"
+
+#include "gegl/gimp-gegl-nodes.h"
+
+#include "gimpdrawable.h"
+#include "gimpimage.h"
+#include "gimpimage-symmetry.h"
+#include "gimpitem.h"
+#include "gimpsymmetry.h"
+
+#include "gimp-intl.h"
+
+
+enum
+{
+  STROKES_UPDATED,
+  GUI_PARAM_CHANGED,
+  ACTIVE_CHANGED,
+  LAST_SIGNAL
+};
+
+enum
+{
+  PROP_0,
+  PROP_IMAGE,
+  PROP_ACTIVE,
+  PROP_VERSION,
+};
+
+
+/* Local function prototypes */
+
+static void       gimp_symmetry_finalize            (GObject      *object);
+static void       gimp_symmetry_set_property        (GObject      *object,
+                                                     guint         property_id,
+                                                     const GValue *value,
+                                                     GParamSpec   *pspec);
+static void       gimp_symmetry_get_property        (GObject      *object,
+                                                     guint         property_id,
+                                                     GValue       *value,
+                                                     GParamSpec   *pspec);
+
+static void       gimp_symmetry_real_update_strokes (GimpSymmetry *sym,
+                                                     GimpDrawable *drawable,
+                                                     GimpCoords   *origin);
+static void       gimp_symmetry_real_get_transform  (GimpSymmetry *sym,
+                                                     gint          stroke,
+                                                     gdouble      *angle,
+                                                     gboolean     *reflect);
+static gboolean   gimp_symmetry_real_update_version (GimpSymmetry *sym);
+
+
+G_DEFINE_TYPE_WITH_CODE (GimpSymmetry, gimp_symmetry, GIMP_TYPE_OBJECT,
+                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_CONFIG, NULL))
+
+#define parent_class gimp_symmetry_parent_class
+
+static guint gimp_symmetry_signals[LAST_SIGNAL] = { 0 };
+
+
+static void
+gimp_symmetry_class_init (GimpSymmetryClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  /* This signal should likely be emitted at the end of
+   * update_strokes() if stroke coordinates were changed.
+   */
+  gimp_symmetry_signals[STROKES_UPDATED] =
+    g_signal_new ("strokes-updated",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  0,
+                  NULL, NULL,
+                  NULL,
+                  G_TYPE_NONE,
+                  1, GIMP_TYPE_IMAGE);
+
+  /* This signal should be emitted when you request a change in the
+   * settings UI. For instance adding some settings (therefore having
+   * a dynamic UI), or changing scale min/max extremes, etc.
+   */
+  gimp_symmetry_signals[GUI_PARAM_CHANGED] =
+    g_signal_new ("gui-param-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  0,
+                  NULL, NULL,
+                  NULL,
+                  G_TYPE_NONE,
+                  1, GIMP_TYPE_IMAGE);
+
+  gimp_symmetry_signals[ACTIVE_CHANGED] =
+    g_signal_new ("active-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpSymmetryClass, active_changed),
+                  NULL, NULL,
+                  NULL,
+                  G_TYPE_NONE, 0);
+
+  object_class->finalize     = gimp_symmetry_finalize;
+  object_class->set_property = gimp_symmetry_set_property;
+  object_class->get_property = gimp_symmetry_get_property;
+
+  klass->label               = _("None");
+  klass->update_strokes      = gimp_symmetry_real_update_strokes;
+  klass->get_transform       = gimp_symmetry_real_get_transform;
+  klass->active_changed      = NULL;
+  klass->update_version      = gimp_symmetry_real_update_version;
+
+  g_object_class_install_property (object_class, PROP_IMAGE,
+                                   g_param_spec_object ("image",
+                                                        NULL, NULL,
+                                                        GIMP_TYPE_IMAGE,
+                                                        GIMP_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT_ONLY));
+  GIMP_CONFIG_PROP_BOOLEAN (object_class, PROP_ACTIVE,
+                            "active",
+                            _("Active"),
+                            _("Activate symmetry painting"),
+                            FALSE,
+                            GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_INT (object_class, PROP_VERSION,
+                        "version",
+                        "Symmetry version",
+                        "Version of the symmetry object",
+                        -1, G_MAXINT, 0,
+                        GIMP_PARAM_STATIC_STRINGS);
+}
+
+static void
+gimp_symmetry_init (GimpSymmetry *sym)
+{
+}
+
+static void
+gimp_symmetry_finalize (GObject *object)
+{
+  GimpSymmetry *sym = GIMP_SYMMETRY (object);
+
+  gimp_symmetry_clear_origin (sym);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gimp_symmetry_set_property (GObject      *object,
+                            guint         property_id,
+                            const GValue *value,
+                            GParamSpec   *pspec)
+{
+  GimpSymmetry *sym = GIMP_SYMMETRY (object);
+
+  switch (property_id)
+    {
+    case PROP_IMAGE:
+      sym->image = g_value_get_object (value);
+      break;
+    case PROP_ACTIVE:
+      sym->active = g_value_get_boolean (value);
+      g_signal_emit (sym, gimp_symmetry_signals[ACTIVE_CHANGED], 0,
+                     sym->active);
+      break;
+    case PROP_VERSION:
+      sym->version = g_value_get_int (value);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_symmetry_get_property (GObject    *object,
+                            guint       property_id,
+                            GValue     *value,
+                            GParamSpec *pspec)
+{
+  GimpSymmetry *sym = GIMP_SYMMETRY (object);
+
+  switch (property_id)
+    {
+    case PROP_IMAGE:
+      g_value_set_object (value, sym->image);
+      break;
+    case PROP_ACTIVE:
+      g_value_set_boolean (value, sym->active);
+      break;
+    case PROP_VERSION:
+      g_value_set_int (value, sym->version);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_symmetry_real_update_strokes (GimpSymmetry *sym,
+                                   GimpDrawable *drawable,
+                                   GimpCoords   *origin)
+{
+  /* The basic symmetry just uses the origin as is. */
+  sym->strokes = g_list_prepend (sym->strokes,
+                                 g_memdup (origin, sizeof (GimpCoords)));
+}
+
+static void
+gimp_symmetry_real_get_transform (GimpSymmetry *sym,
+                                  gint          stroke,
+                                  gdouble      *angle,
+                                  gboolean     *reflect)
+{
+  /* The basic symmetry does nothing, since no transformation of the
+   * brush painting happen. */
+}
+
+static gboolean
+gimp_symmetry_real_update_version (GimpSymmetry *symmetry)
+{
+  /* Currently all symmetries are at version 0. So all this check has to
+   * do is verify that we are at version 0.
+   * If one of the child symmetry bumps its version, it will have to
+   * override the update_version() virtual function and do any necessary
+   * update there (for instance new properties, modified properties, or
+   * whatnot).
+   */
+  gint version;
+
+  g_object_get (symmetry,
+                "version", &version,
+                NULL);
+
+  return (version == 0);
+}
+
+/***** Public Functions *****/
+
+/**
+ * gimp_symmetry_set_stateful:
+ * @sym:      the #GimpSymmetry
+ * @stateful: whether the symmetry should be stateful or stateless.
+ *
+ * By default, symmetry is made stateless, which means in particular
+ * that the size of points can change from one stroke to the next, and
+ * in particular you cannot map the coordinates from a stroke to the
+ * next. I.e. stroke N at time T+1 is not necessarily the continuation
+ * of stroke N at time T.
+ * To obtain corresponding strokes, stateful tools, such as MyPaint
+ * brushes or the ink tool, need to run this function. They should reset
+ * to stateless behavior once finished painting.
+ *
+ * One of the first consequence of being stateful is that the number of
+ * strokes cannot be changed, so more strokes than possible on canvas
+ * may be computed, and oppositely it will be possible to end up in
+ * cases with missing strokes (e.g. a tiling, theoretically infinite,
+ * won't be for the ink tool if one draws too far out of canvas).
+ **/
+void
+gimp_symmetry_set_stateful (GimpSymmetry *symmetry,
+                            gboolean      stateful)
+{
+  symmetry->stateful = stateful;
+}
+
+/**
+ * gimp_symmetry_set_origin:
+ * @sym:      the #GimpSymmetry
+ * @drawable: the #GimpDrawable where painting will happen
+ * @origin:   new base coordinates.
+ *
+ * Set the symmetry to new origin coordinates and drawable.
+ **/
+void
+gimp_symmetry_set_origin (GimpSymmetry *sym,
+                          GimpDrawable *drawable,
+                          GimpCoords   *origin)
+{
+  g_return_if_fail (GIMP_IS_SYMMETRY (sym));
+  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
+  g_return_if_fail (gimp_item_get_image (GIMP_ITEM (drawable)) == sym->image);
+
+  if (drawable != sym->drawable)
+    {
+      if (sym->drawable)
+        g_object_unref (sym->drawable);
+      sym->drawable = g_object_ref (drawable);
+    }
+
+  if (origin != sym->origin)
+    {
+      g_free (sym->origin);
+      sym->origin = g_memdup (origin, sizeof (GimpCoords));
+    }
+
+  g_list_free_full (sym->strokes, g_free);
+  sym->strokes = NULL;
+
+  GIMP_SYMMETRY_GET_CLASS (sym)->update_strokes (sym, drawable, origin);
+}
+
+/**
+ * gimp_symmetry_clear_origin:
+ * @sym: the #GimpSymmetry
+ *
+ * Clear the symmetry's origin coordinates and drawable.
+ **/
+void
+gimp_symmetry_clear_origin (GimpSymmetry *sym)
+{
+  g_return_if_fail (GIMP_IS_SYMMETRY (sym));
+
+  g_clear_object (&sym->drawable);
+
+  g_clear_pointer (&sym->origin, g_free);
+
+  g_list_free_full (sym->strokes, g_free);
+  sym->strokes = NULL;
+}
+
+/**
+ * gimp_symmetry_get_origin:
+ * @sym: the #GimpSymmetry
+ *
+ * Returns: the origin stroke coordinates.
+ * The returned value is owned by the #GimpSymmetry and must not be freed.
+ **/
+GimpCoords *
+gimp_symmetry_get_origin (GimpSymmetry *sym)
+{
+  g_return_val_if_fail (GIMP_IS_SYMMETRY (sym), NULL);
+
+  return sym->origin;
+}
+
+/**
+ * gimp_symmetry_get_size:
+ * @sym: the #GimpSymmetry
+ *
+ * Returns: the total number of strokes.
+ **/
+gint
+gimp_symmetry_get_size (GimpSymmetry *sym)
+{
+  g_return_val_if_fail (GIMP_IS_SYMMETRY (sym), 0);
+
+  return g_list_length (sym->strokes);
+}
+
+/**
+ * gimp_symmetry_get_coords:
+ * @sym:    the #GimpSymmetry
+ * @stroke: the stroke number
+ *
+ * Returns: the coordinates of the stroke number @stroke.
+ * The returned value is owned by the #GimpSymmetry and must not be freed.
+ **/
+GimpCoords *
+gimp_symmetry_get_coords (GimpSymmetry *sym,
+                          gint          stroke)
+{
+  g_return_val_if_fail (GIMP_IS_SYMMETRY (sym), NULL);
+
+  return g_list_nth_data (sym->strokes, stroke);
+}
+
+/**
+ * gimp_symmetry_get_transform:
+ * @sym:     the #GimpSymmetry
+ * @stroke:  the stroke number
+ * @angle:   output pointer to the transformation rotation angle,
+ *           in degrees (ccw)
+ * @reflect: output pointer to the transformation reflection flag
+ *
+ * Returns: the transformation to apply to the paint content for stroke
+ * number @stroke.  The transformation is comprised of rotation, possibly
+ * followed by horizontal reflection, around the stroke coordinates.
+ **/
+void
+gimp_symmetry_get_transform (GimpSymmetry *sym,
+                             gint          stroke,
+                             gdouble      *angle,
+                             gboolean     *reflect)
+{
+  g_return_if_fail (GIMP_IS_SYMMETRY (sym));
+  g_return_if_fail (angle != NULL);
+  g_return_if_fail (reflect != NULL);
+
+  *angle   = 0.0;
+  *reflect = FALSE;
+
+  GIMP_SYMMETRY_GET_CLASS (sym)->get_transform (sym,
+                                                stroke,
+                                                angle,
+                                                reflect);
+}
+
+/**
+ * gimp_symmetry_get_matrix:
+ * @sym:     the #GimpSymmetry
+ * @stroke:  the stroke number
+ * @matrix:  output pointer to the transformation matrix
+ *
+ * Returns: the transformation matrix to apply to the paint content for stroke
+ * number @stroke.
+ **/
+void
+gimp_symmetry_get_matrix (GimpSymmetry *sym,
+                          gint          stroke,
+                          GimpMatrix3  *matrix)
+{
+  gdouble  angle;
+  gboolean reflect;
+
+  g_return_if_fail (GIMP_IS_SYMMETRY (sym));
+  g_return_if_fail (matrix != NULL);
+
+  gimp_symmetry_get_transform (sym, stroke, &angle, &reflect);
+
+  gimp_matrix3_identity (matrix);
+  gimp_matrix3_rotate (matrix, -gimp_deg_to_rad (angle));
+  if (reflect)
+    gimp_matrix3_scale (matrix, -1.0, 1.0);
+}
+
+/**
+ * gimp_symmetry_get_operation:
+ * @sym:          the #GimpSymmetry
+ * @stroke:       the stroke number
+ *
+ * Returns: the transformation operation to apply to the paint content for
+ * stroke number @stroke, or NULL for the identity transformation.
+ *
+ * The returned #GeglNode should be freed by the caller.
+ **/
+GeglNode *
+gimp_symmetry_get_operation (GimpSymmetry *sym,
+                             gint          stroke)
+{
+  GimpMatrix3 matrix;
+
+  g_return_val_if_fail (GIMP_IS_SYMMETRY (sym), NULL);
+
+  gimp_symmetry_get_matrix (sym, stroke, &matrix);
+
+  if (gimp_matrix3_is_identity (&matrix))
+    return NULL;
+
+  return gimp_gegl_create_transform_node (&matrix);
+}
+
+/*
+ * gimp_symmetry_parasite_name:
+ * @type: the #GimpSymmetry's #GType
+ *
+ * Returns: a newly allocated string.
+ */
+gchar *
+gimp_symmetry_parasite_name (GType type)
+{
+  return g_strconcat ("gimp-image-symmetry:", g_type_name (type), NULL);
+}
+
+GimpParasite *
+gimp_symmetry_to_parasite (const GimpSymmetry *sym)
+{
+  GimpParasite *parasite;
+  gchar        *parasite_name;
+  gchar        *str;
+
+  g_return_val_if_fail (GIMP_IS_SYMMETRY (sym), NULL);
+
+  str = gimp_config_serialize_to_string (GIMP_CONFIG (sym), NULL);
+  g_return_val_if_fail (str != NULL, NULL);
+
+  parasite_name = gimp_symmetry_parasite_name (G_TYPE_FROM_INSTANCE (sym));
+  parasite = gimp_parasite_new (parasite_name,
+                                GIMP_PARASITE_PERSISTENT,
+                                strlen (str) + 1, str);
+  g_free (parasite_name);
+  g_free (str);
+
+  return parasite;
+}
+
+GimpSymmetry *
+gimp_symmetry_from_parasite (const GimpParasite *parasite,
+                             GimpImage          *image,
+                             GType               type)
+{
+  GimpSymmetry    *symmetry;
+  gchar           *parasite_name;
+  const gchar     *str;
+  GError          *error = NULL;
+
+  parasite_name = gimp_symmetry_parasite_name (type);
+
+  g_return_val_if_fail (parasite != NULL, NULL);
+  g_return_val_if_fail (strcmp (gimp_parasite_name (parasite),
+                                parasite_name) == 0,
+                        NULL);
+
+  str = gimp_parasite_data (parasite);
+
+  if (! str)
+    {
+      g_warning ("Empty symmetry parasite \"%s\"", parasite_name);
+
+      return NULL;
+    }
+
+  symmetry = gimp_image_symmetry_new (image, type);
+
+  g_object_set (symmetry,
+                "version", -1,
+                NULL);
+
+  if (! gimp_config_deserialize_string (GIMP_CONFIG (symmetry),
+                                        str,
+                                        gimp_parasite_data_size (parasite),
+                                        NULL,
+                                        &error))
+    {
+      g_printerr ("Failed to deserialize symmetry parasite: %s\n"
+                  "\t- parasite name: %s\n\t- parasite data: %s\n",
+                  error->message, parasite_name, str);
+      g_error_free (error);
+
+      g_object_unref (symmetry);
+      symmetry = NULL;
+    }
+  g_free (parasite_name);
+
+  if (symmetry)
+    {
+      gint version;
+
+      g_object_get (symmetry,
+                    "version", &version,
+                    NULL);
+      if (version == -1)
+        {
+          /* If version has not been updated, let's assume this parasite was
+           * not representing symmetry settings.
+           */
+          g_object_unref (symmetry);
+          symmetry = NULL;
+        }
+      else if (GIMP_SYMMETRY_GET_CLASS (symmetry)->update_version (symmetry) &&
+               ! GIMP_SYMMETRY_GET_CLASS (symmetry)->update_version (symmetry))
+        {
+          g_object_unref (symmetry);
+          symmetry = NULL;
+        }
+    }
+
+  return symmetry;
+}
diff --git a/app/core/gimpsymmetry.h b/app/core/gimpsymmetry.h
new file mode 100644
index 0000000..9474662
--- /dev/null
+++ b/app/core/gimpsymmetry.h
@@ -0,0 +1,106 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpsymmetry.h
+ * Copyright (C) 2015 Jehan <jehan@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_SYMMETRY_H__
+#define __GIMP_SYMMETRY_H__
+
+
+#include "gimpobject.h"
+
+
+/* shift one more than GIMP_CONFIG_PARAM_IGNORE */
+#define GIMP_SYMMETRY_PARAM_GUI (1 << (6 + G_PARAM_USER_SHIFT))
+
+
+#define GIMP_TYPE_SYMMETRY            (gimp_symmetry_get_type ())
+#define GIMP_SYMMETRY(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_SYMMETRY, GimpSymmetry))
+#define GIMP_SYMMETRY_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_SYMMETRY, GimpSymmetryClass))
+#define GIMP_IS_SYMMETRY(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_SYMMETRY))
+#define GIMP_IS_SYMMETRY_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_SYMMETRY))
+#define GIMP_SYMMETRY_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_SYMMETRY, GimpSymmetryClass))
+
+
+typedef struct _GimpSymmetryClass   GimpSymmetryClass;
+
+struct _GimpSymmetry
+{
+  GimpObject    parent_instance;
+
+  GimpImage    *image;
+  GimpDrawable *drawable;
+  GimpCoords   *origin;
+  gboolean      active;
+  gint          version;
+
+  GList        *strokes;
+  gboolean      stateful;
+};
+
+struct _GimpSymmetryClass
+{
+  GimpObjectClass  parent_class;
+
+  const gchar * label;
+
+  /* Virtual functions */
+  void       (* update_strokes)             (GimpSymmetry       *symmetry,
+                                             GimpDrawable       *drawable,
+                                             GimpCoords         *origin);
+  void       (* get_transform)              (GimpSymmetry       *symmetry,
+                                             gint                stroke,
+                                             gdouble            *angle,
+                                             gboolean           *reflect);
+  void       (* active_changed)             (GimpSymmetry       *symmetry);
+
+  gboolean   (* update_version)             (GimpSymmetry       *symmetry);
+};
+
+
+GType          gimp_symmetry_get_type       (void) G_GNUC_CONST;
+
+void           gimp_symmetry_set_stateful   (GimpSymmetry       *symmetry,
+                                             gboolean            stateful);
+void           gimp_symmetry_set_origin     (GimpSymmetry       *symmetry,
+                                             GimpDrawable       *drawable,
+                                             GimpCoords         *origin);
+void           gimp_symmetry_clear_origin   (GimpSymmetry       *symmetry);
+
+GimpCoords   * gimp_symmetry_get_origin     (GimpSymmetry       *symmetry);
+gint           gimp_symmetry_get_size       (GimpSymmetry       *symmetry);
+GimpCoords   * gimp_symmetry_get_coords     (GimpSymmetry       *symmetry,
+                                             gint                stroke);
+void           gimp_symmetry_get_transform  (GimpSymmetry       *symmetry,
+                                             gint                stroke,
+                                             gdouble            *angle,
+                                             gboolean           *reflect);
+void           gimp_symmetry_get_matrix     (GimpSymmetry       *symmetry,
+                                             gint                stroke,
+                                             GimpMatrix3        *matrix);
+GeglNode     * gimp_symmetry_get_operation  (GimpSymmetry       *symmetry,
+                                             gint                stroke);
+
+gchar        * gimp_symmetry_parasite_name  (GType               type);
+GimpParasite * gimp_symmetry_to_parasite    (const GimpSymmetry *symmetry);
+GimpSymmetry * gimp_symmetry_from_parasite  (const GimpParasite *parasite,
+                                             GimpImage          *image,
+                                             GType               type);
+
+
+#endif  /*  __GIMP_SYMMETRY_H__  */
diff --git a/app/core/gimptag.c b/app/core/gimptag.c
new file mode 100644
index 0000000..95c4954
--- /dev/null
+++ b/app/core/gimptag.c
@@ -0,0 +1,442 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimptag.c
+ * Copyright (C) 2008 Aurimas Juška <aurisj@svn.gnome.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <glib-object.h>
+#include <string.h>
+
+#include "core-types.h"
+
+#include "gimptag.h"
+
+
+#define GIMP_TAG_INTERNAL_PREFIX "gimp:"
+
+
+G_DEFINE_TYPE (GimpTag, gimp_tag, G_TYPE_OBJECT)
+
+#define parent_class gimp_tag_parent_class
+
+
+static void
+gimp_tag_class_init (GimpTagClass *klass)
+{
+}
+
+static void
+gimp_tag_init (GimpTag *tag)
+{
+  tag->tag         = 0;
+  tag->collate_key = 0;
+  tag->internal    = FALSE;
+}
+
+/**
+ * gimp_tag_new:
+ * @tag_string: a tag name.
+ *
+ * If given tag name is not valid, an attempt will be made to fix it.
+ *
+ * Return value: a new #GimpTag object, or NULL if tag string is invalid and
+ * cannot be fixed.
+ **/
+GimpTag *
+gimp_tag_new (const char *tag_string)
+{
+  GimpTag *tag;
+  gchar   *tag_name;
+  gchar   *case_folded;
+  gchar   *collate_key;
+
+  g_return_val_if_fail (tag_string != NULL, NULL);
+
+  tag_name = gimp_tag_string_make_valid (tag_string);
+  if (! tag_name)
+    return NULL;
+
+  tag = g_object_new (GIMP_TYPE_TAG, NULL);
+
+  tag->tag = g_quark_from_string (tag_name);
+
+  case_folded = g_utf8_casefold (tag_name, -1);
+  collate_key = g_utf8_collate_key (case_folded, -1);
+  tag->collate_key = g_quark_from_string (collate_key);
+  g_free (collate_key);
+  g_free (case_folded);
+  g_free (tag_name);
+
+  return tag;
+}
+
+/**
+ * gimp_tag_try_new:
+ * @tag_string: a tag name.
+ *
+ * Similar to gimp_tag_new(), but returns NULL if tag is surely not equal
+ * to any of currently created tags. It is useful for tag querying to avoid
+ * unneeded comparisons. If tag is created, however, it does not mean that
+ * it would necessarily match with some other tag.
+ *
+ * Return value: new #GimpTag object, or NULL if tag will not match with any
+ * other #GimpTag.
+ **/
+GimpTag *
+gimp_tag_try_new (const char *tag_string)
+{
+  GimpTag *tag;
+  gchar   *tag_name;
+  gchar   *case_folded;
+  gchar   *collate_key;
+  GQuark   tag_quark;
+  GQuark   collate_key_quark;
+
+  tag_name = gimp_tag_string_make_valid (tag_string);
+  if (! tag_name)
+    return NULL;
+
+  case_folded = g_utf8_casefold (tag_name, -1);
+  collate_key = g_utf8_collate_key (case_folded, -1);
+  collate_key_quark = g_quark_try_string (collate_key);
+  g_free (collate_key);
+  g_free (case_folded);
+
+  if (! collate_key_quark)
+    {
+      g_free (tag_name);
+      return NULL;
+    }
+
+  tag_quark = g_quark_from_string (tag_name);
+  g_free (tag_name);
+  if (! tag_quark)
+    return NULL;
+
+  tag = g_object_new (GIMP_TYPE_TAG, NULL);
+  tag->tag = tag_quark;
+  tag->collate_key = collate_key_quark;
+
+  return tag;
+}
+
+/**
+ * gimp_tag_get_internal:
+ * @tag: a gimp tag.
+ *
+ * Retrieve internal status of the tag.
+ *
+ * Return value: internal status of tag. Internal tags are not saved.
+ **/
+gboolean
+gimp_tag_get_internal (GimpTag *tag)
+{
+  g_return_val_if_fail (GIMP_IS_TAG (tag), FALSE);
+
+  return tag->internal;
+}
+
+/**
+ * gimp_tag_set_internal:
+ * @tag: a gimp tag.
+ * @internal: desired tag internal status
+ *
+ * Set internal status of the tag. Internal tags are usually automatically
+ * generated and will not be saved into users tag cache.
+ *
+ **/
+void
+gimp_tag_set_internal (GimpTag *tag, gboolean internal)
+{
+  g_return_if_fail (GIMP_IS_TAG (tag));
+
+  tag->internal = internal;
+}
+
+
+/**
+ * gimp_tag_get_name:
+ * @tag: a gimp tag.
+ *
+ * Retrieve name of the tag.
+ *
+ * Return value: name of tag.
+ **/
+const gchar *
+gimp_tag_get_name (GimpTag *tag)
+{
+  g_return_val_if_fail (GIMP_IS_TAG (tag), NULL);
+
+  return g_quark_to_string (tag->tag);
+}
+
+/**
+ * gimp_tag_get_hash:
+ * @tag: a gimp tag.
+ *
+ * Hashing function which is useful, for example, to store #GimpTag in
+ * a #GHashTable.
+ *
+ * Return value: hash value for tag.
+ **/
+guint
+gimp_tag_get_hash (GimpTag *tag)
+{
+  g_return_val_if_fail (GIMP_IS_TAG (tag), -1);
+
+  return tag->collate_key;
+}
+
+/**
+ * gimp_tag_equals:
+ * @tag:   a gimp tag.
+ * @other: another gimp tag to compare with.
+ *
+ * Compares tags for equality according to tag comparison rules.
+ *
+ * Return value: TRUE if tags are equal, FALSE otherwise.
+ **/
+gboolean
+gimp_tag_equals (GimpTag *tag,
+                 GimpTag *other)
+{
+  g_return_val_if_fail (GIMP_IS_TAG (tag), FALSE);
+  g_return_val_if_fail (GIMP_IS_TAG (other), FALSE);
+
+  return tag->collate_key == other->collate_key;
+}
+
+/**
+ * gimp_tag_compare_func:
+ * @p1: pointer to left-hand #GimpTag object.
+ * @p2: pointer to right-hand #GimpTag object.
+ *
+ * Compares tags according to tag comparison rules. Useful for sorting
+ * functions.
+ *
+ * Return value: meaning of return value is the same as in strcmp().
+ **/
+int
+gimp_tag_compare_func (const void *p1,
+                       const void *p2)
+{
+  GimpTag      *t1 = GIMP_TAG (p1);
+  GimpTag      *t2 = GIMP_TAG (p2);
+
+  return g_strcmp0 (g_quark_to_string (t1->collate_key),
+                    g_quark_to_string (t2->collate_key));
+}
+
+/**
+ * gimp_tag_compare_with_string:
+ * @tag:        a #GimpTag object.
+ * @tag_string: the string to compare to.
+ *
+ * Compares tag and a string according to tag comparison rules. Similar to
+ * gimp_tag_compare_func(), but can be used without creating temporary tag
+ * object.
+ *
+ * Return value: meaning of return value is the same as in strcmp().
+ **/
+gint
+gimp_tag_compare_with_string (GimpTag     *tag,
+                              const gchar *tag_string)
+{
+  gchar        *case_folded;
+  const gchar  *collate_key;
+  gchar        *collate_key2;
+  gint          result;
+
+  g_return_val_if_fail (GIMP_IS_TAG (tag), 0);
+  g_return_val_if_fail (tag_string != NULL, 0);
+
+  collate_key = g_quark_to_string (tag->collate_key);
+  case_folded = g_utf8_casefold (tag_string, -1);
+  collate_key2 = g_utf8_collate_key (case_folded, -1);
+  result = g_strcmp0 (collate_key, collate_key2);
+  g_free (collate_key2);
+  g_free (case_folded);
+
+  return result;
+}
+
+/**
+ * gimp_tag_has_prefix:
+ * @tag:           a #GimpTag object.
+ * @prefix_string: the prefix to compare to.
+ *
+ * Compares tag and a prefix according to tag comparison rules. Similar to
+ * gimp_tag_compare_with_string(), but does not work on the collate key
+ * because that can't be matched partially.
+ *
+ * Return value: wheher #tag starts with @prefix_string.
+ **/
+gboolean
+gimp_tag_has_prefix (GimpTag     *tag,
+                     const gchar *prefix_string)
+{
+  gchar    *case_folded1;
+  gchar    *case_folded2;
+  gboolean  has_prefix;
+
+  g_return_val_if_fail (GIMP_IS_TAG (tag), FALSE);
+  g_return_val_if_fail (prefix_string != NULL, FALSE);
+
+  case_folded1 = g_utf8_casefold (g_quark_to_string (tag->tag), -1);
+  case_folded2 = g_utf8_casefold (prefix_string, -1);
+
+  has_prefix = g_str_has_prefix (case_folded1, case_folded2);
+
+  g_free (case_folded1);
+  g_free (case_folded2);
+
+  g_printerr ("'%s' has prefix '%s': %d\n",
+              g_quark_to_string (tag->tag), prefix_string, has_prefix);
+
+  return has_prefix;
+}
+
+/**
+ * gimp_tag_string_make_valid:
+ * @tag_string: a text string.
+ *
+ * Tries to create a valid tag string from given @tag_string.
+ *
+ * Return value: a newly allocated tag string in case given @tag_string was
+ * valid or could be fixed, otherwise NULL. Allocated value should be freed
+ * using g_free().
+ **/
+gchar *
+gimp_tag_string_make_valid (const gchar *tag_string)
+{
+  gchar    *tag;
+  GString  *buffer;
+  gchar    *tag_cursor;
+  gunichar  c;
+
+  g_return_val_if_fail (tag_string, NULL);
+
+  tag = g_utf8_normalize (tag_string, -1, G_NORMALIZE_ALL);
+  if (! tag)
+    return NULL;
+
+  tag = g_strstrip (tag);
+  if (! *tag)
+    {
+      g_free (tag);
+      return NULL;
+    }
+
+  buffer = g_string_new ("");
+  tag_cursor = tag;
+  if (g_str_has_prefix (tag_cursor, GIMP_TAG_INTERNAL_PREFIX))
+    {
+      tag_cursor += strlen (GIMP_TAG_INTERNAL_PREFIX);
+    }
+  do
+    {
+      c = g_utf8_get_char (tag_cursor);
+      tag_cursor = g_utf8_next_char (tag_cursor);
+      if (g_unichar_isprint (c)
+          && ! gimp_tag_is_tag_separator (c))
+        {
+          g_string_append_unichar (buffer, c);
+        }
+    } while (c);
+
+  g_free (tag);
+  tag = g_string_free (buffer, FALSE);
+  tag = g_strstrip (tag);
+
+  if (! *tag)
+    {
+      g_free (tag);
+      return NULL;
+    }
+
+  return tag;
+}
+
+/**
+ * gimp_tag_is_tag_separator:
+ * @c: Unicode character.
+ *
+ * Defines a set of characters that are considered tag separators. The
+ * tag separators are hand-picked from the set of characters with the
+ * Terminal_Punctuation property as specified in the version 5.1.0 of
+ * the Unicode Standard.
+ *
+ * Return value: %TRUE if the character is a tag separator.
+ */
+gboolean
+gimp_tag_is_tag_separator (gunichar c)
+{
+  switch (c)
+    {
+    case 0x002C: /* COMMA */
+    case 0x060C: /* ARABIC COMMA */
+    case 0x07F8: /* NKO COMMA */
+    case 0x1363: /* ETHIOPIC COMMA */
+    case 0x1802: /* MONGOLIAN COMMA */
+    case 0x1808: /* MONGOLIAN MANCHU COMMA */
+    case 0x3001: /* IDEOGRAPHIC COMMA */
+    case 0xA60D: /* VAI COMMA */
+    case 0xFE50: /* SMALL COMMA */
+    case 0xFF0C: /* FULLWIDTH COMMA */
+    case 0xFF64: /* HALFWIDTH IDEOGRAPHIC COMMA */
+      return TRUE;
+
+    default:
+      return FALSE;
+    }
+}
+
+/**
+ * gimp_tag_or_null_ref:
+ * @tag: a #GimpTag
+ *
+ * A simple wrapper around g_object_ref() that silently accepts #NULL.
+ **/
+void
+gimp_tag_or_null_ref (GimpTag *tag_or_null)
+{
+  if (tag_or_null)
+    {
+      g_return_if_fail (GIMP_IS_TAG (tag_or_null));
+
+      g_object_ref (tag_or_null);
+    }
+}
+
+/**
+ * gimp_tag_or_null_unref:
+ * @tag: a #GimpTag
+ *
+ * A simple wrapper around g_object_unref() that silently accepts #NULL.
+ **/
+void
+gimp_tag_or_null_unref (GimpTag *tag_or_null)
+{
+  if (tag_or_null)
+    {
+      g_return_if_fail (GIMP_IS_TAG (tag_or_null));
+
+      g_object_unref (tag_or_null);
+    }
+}
diff --git a/app/core/gimptag.h b/app/core/gimptag.h
new file mode 100644
index 0000000..0cd6c32
--- /dev/null
+++ b/app/core/gimptag.h
@@ -0,0 +1,80 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimptag.h
+ * Copyright (C) 2008 Aurimas Juška <aurisj@svn.gnome.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_TAG_H__
+#define __GIMP_TAG_H__
+
+
+#include <glib-object.h>
+
+
+#define GIMP_TYPE_TAG            (gimp_tag_get_type ())
+#define GIMP_TAG(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_TAG, GimpTag))
+#define GIMP_TAG_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_TAG, GimpTagClass))
+#define GIMP_IS_TAG(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_TAG))
+#define GIMP_IS_TAG_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_TAG))
+#define GIMP_TAG_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_TAG, GimpTagClass))
+
+
+typedef struct _GimpTagClass    GimpTagClass;
+
+struct _GimpTag
+{
+  GObject parent_instance;
+
+  GQuark  tag;
+  GQuark  collate_key;
+
+  gboolean internal; /* Tags that are not serialized to disk */
+};
+
+struct _GimpTagClass
+{
+  GObjectClass parent_class;
+};
+
+GType         gimp_tag_get_type            (void) G_GNUC_CONST;
+
+GimpTag     * gimp_tag_new                 (const gchar *tag_string);
+GimpTag     * gimp_tag_try_new             (const gchar *tag_string);
+
+const gchar * gimp_tag_get_name            (GimpTag     *tag);
+guint         gimp_tag_get_hash            (GimpTag     *tag);
+
+gboolean      gimp_tag_get_internal        (GimpTag     *tag);
+void          gimp_tag_set_internal        (GimpTag     *tag,
+                                            gboolean     internal);
+
+gboolean      gimp_tag_equals              (GimpTag     *tag,
+                                            GimpTag     *other);
+gint          gimp_tag_compare_func        (const void  *p1,
+                                            const void  *p2);
+gint          gimp_tag_compare_with_string (GimpTag     *tag,
+                                            const gchar *tag_string);
+gboolean      gimp_tag_has_prefix          (GimpTag     *tag,
+                                            const gchar *prefix_string);
+gchar       * gimp_tag_string_make_valid   (const gchar *tag_string);
+gboolean      gimp_tag_is_tag_separator    (gunichar     c);
+
+void          gimp_tag_or_null_ref         (GimpTag     *tag_or_null);
+void          gimp_tag_or_null_unref       (GimpTag     *tag_or_null);
+
+
+#endif /* __GIMP_TAG_H__ */
diff --git a/app/core/gimptagcache.c b/app/core/gimptagcache.c
new file mode 100644
index 0000000..a0e4534
--- /dev/null
+++ b/app/core/gimptagcache.c
@@ -0,0 +1,646 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimptagcache.c
+ * Copyright (C) 2008 Aurimas Juška <aurisj@svn.gnome.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpmath/gimpmath.h"
+#include "libgimpconfig/gimpconfig.h"
+
+#include "core-types.h"
+
+#include "config/gimpxmlparser.h"
+
+#include "gimp-memsize.h"
+#include "gimpcontext.h"
+#include "gimpdata.h"
+#include "gimplist.h"
+#include "gimptag.h"
+#include "gimptagcache.h"
+#include "gimptagged.h"
+
+#include "gimp-intl.h"
+
+
+#define GIMP_TAG_CACHE_FILE  "tags.xml"
+
+/* #define DEBUG_GIMP_TAG_CACHE  1 */
+
+
+enum
+{
+  PROP_0,
+  PROP_GIMP
+};
+
+
+typedef struct
+{
+  GQuark  identifier;
+  GQuark  checksum;
+  GList  *tags;
+  guint   referenced : 1;
+} GimpTagCacheRecord;
+
+typedef struct
+{
+  GArray             *records;
+  GimpTagCacheRecord  current_record;
+} GimpTagCacheParseData;
+
+struct _GimpTagCachePrivate
+{
+  GArray *records;
+  GList  *containers;
+};
+
+
+static void          gimp_tag_cache_finalize           (GObject                *object);
+
+static gint64        gimp_tag_cache_get_memsize        (GimpObject             *object,
+                                                        gint64                 *gui_size);
+static void          gimp_tag_cache_object_initialize  (GimpTagged             *tagged,
+                                                        GimpTagCache           *cache);
+static void          gimp_tag_cache_add_object         (GimpTagCache           *cache,
+                                                        GimpTagged             *tagged);
+
+static void          gimp_tag_cache_load_start_element (GMarkupParseContext    *context,
+                                                        const gchar            *element_name,
+                                                        const gchar           **attribute_names,
+                                                        const gchar           **attribute_values,
+                                                        gpointer                user_data,
+                                                        GError                **error);
+static void          gimp_tag_cache_load_end_element   (GMarkupParseContext    *context,
+                                                        const gchar            *element_name,
+                                                        gpointer                user_data,
+                                                        GError                **error);
+static void          gimp_tag_cache_load_text          (GMarkupParseContext    *context,
+                                                        const gchar            *text,
+                                                        gsize                   text_len,
+                                                        gpointer                user_data,
+                                                        GError                **error);
+static  void         gimp_tag_cache_load_error         (GMarkupParseContext    *context,
+                                                        GError                 *error,
+                                                        gpointer                user_data);
+static const gchar * gimp_tag_cache_attribute_name_to_value
+                                                       (const gchar           **attribute_names,
+                                                        const gchar           **attribute_values,
+                                                        const gchar            *name);
+
+static GQuark        gimp_tag_cache_get_error_domain   (void);
+
+
+G_DEFINE_TYPE_WITH_PRIVATE (GimpTagCache, gimp_tag_cache, GIMP_TYPE_OBJECT)
+
+#define parent_class gimp_tag_cache_parent_class
+
+
+static void
+gimp_tag_cache_class_init (GimpTagCacheClass *klass)
+{
+  GObjectClass    *object_class      = G_OBJECT_CLASS (klass);
+  GimpObjectClass *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+
+  object_class->finalize         = gimp_tag_cache_finalize;
+
+  gimp_object_class->get_memsize = gimp_tag_cache_get_memsize;
+}
+
+static void
+gimp_tag_cache_init (GimpTagCache *cache)
+{
+  cache->priv = gimp_tag_cache_get_instance_private (cache);
+
+  cache->priv->records    = g_array_new (FALSE, FALSE,
+                                         sizeof (GimpTagCacheRecord));
+  cache->priv->containers = NULL;
+}
+
+static void
+gimp_tag_cache_finalize (GObject *object)
+{
+  GimpTagCache *cache = GIMP_TAG_CACHE (object);
+
+  if (cache->priv->records)
+    {
+      gint i;
+
+      for (i = 0; i < cache->priv->records->len; i++)
+        {
+          GimpTagCacheRecord *rec = &g_array_index (cache->priv->records,
+                                                    GimpTagCacheRecord, i);
+
+          g_list_free_full (rec->tags, (GDestroyNotify) g_object_unref);
+        }
+
+      g_array_free (cache->priv->records, TRUE);
+      cache->priv->records = NULL;
+    }
+
+  if (cache->priv->containers)
+    {
+      g_list_free (cache->priv->containers);
+      cache->priv->containers = NULL;
+    }
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static gint64
+gimp_tag_cache_get_memsize (GimpObject *object,
+                            gint64     *gui_size)
+{
+  GimpTagCache *cache   = GIMP_TAG_CACHE (object);
+  gint64        memsize = 0;
+
+  memsize += gimp_g_list_get_memsize (cache->priv->containers, 0);
+  memsize += cache->priv->records->len * sizeof (GimpTagCacheRecord);
+
+  return memsize + GIMP_OBJECT_CLASS (parent_class)->get_memsize (object,
+                                                                  gui_size);
+}
+
+/**
+ * gimp_tag_cache_new:
+ *
+ * Return value: creates new GimpTagCache object.
+ **/
+GimpTagCache *
+gimp_tag_cache_new (void)
+{
+  return g_object_new (GIMP_TYPE_TAG_CACHE, NULL);
+}
+
+static void
+gimp_tag_cache_container_add_callback (GimpTagCache  *cache,
+                                       GimpTagged    *tagged,
+                                       GimpContainer *not_used)
+{
+  gimp_tag_cache_add_object (cache, tagged);
+}
+
+/**
+ * gimp_tag_cache_add_container:
+ * @cache:      a GimpTagCache object.
+ * @container:  container containing GimpTagged objects.
+ *
+ * Adds container of GimpTagged objects to tag cache. Before calling this
+ * function tag cache must be loaded using gimp_tag_cache_load(). When tag
+ * cache is saved to file, tags are collected from objects in priv->containers.
+ **/
+void
+gimp_tag_cache_add_container (GimpTagCache  *cache,
+                              GimpContainer *container)
+{
+  g_return_if_fail (GIMP_IS_TAG_CACHE (cache));
+  g_return_if_fail (GIMP_IS_CONTAINER (container));
+
+  cache->priv->containers = g_list_append (cache->priv->containers, container);
+  gimp_container_foreach (container, (GFunc) gimp_tag_cache_object_initialize,
+                          cache);
+
+  g_signal_connect_swapped (container, "add",
+                            G_CALLBACK (gimp_tag_cache_container_add_callback),
+                            cache);
+}
+
+static void
+gimp_tag_cache_add_object (GimpTagCache *cache,
+                           GimpTagged   *tagged)
+{
+  gchar  *identifier;
+  GQuark  identifier_quark = 0;
+  gchar  *checksum;
+  GQuark  checksum_quark = 0;
+  GList  *list;
+  gint    i;
+
+  identifier = gimp_tagged_get_identifier (tagged);
+
+  if (identifier)
+    {
+      identifier_quark = g_quark_try_string (identifier);
+      g_free (identifier);
+    }
+
+  if (identifier_quark)
+    {
+      for (i = 0; i < cache->priv->records->len; i++)
+        {
+          GimpTagCacheRecord *rec = &g_array_index (cache->priv->records,
+                                                    GimpTagCacheRecord, i);
+
+          if (rec->identifier == identifier_quark)
+            {
+              for (list = rec->tags; list; list = g_list_next (list))
+                {
+                  gimp_tagged_add_tag (tagged, GIMP_TAG (list->data));
+                }
+
+              rec->referenced = TRUE;
+              return;
+            }
+        }
+    }
+
+  checksum = gimp_tagged_get_checksum (tagged);
+
+  if (checksum)
+    {
+      checksum_quark = g_quark_try_string (checksum);
+      g_free (checksum);
+    }
+
+  if (checksum_quark)
+    {
+      for (i = 0; i < cache->priv->records->len; i++)
+        {
+          GimpTagCacheRecord *rec = &g_array_index (cache->priv->records,
+                                                    GimpTagCacheRecord, i);
+
+          if (rec->checksum == checksum_quark)
+            {
+#if DEBUG_GIMP_TAG_CACHE
+              g_printerr ("remapping identifier: %s ==> %s\n",
+                          rec->identifier ? g_quark_to_string (rec->identifier) : "(NULL)",
+                          identifier_quark ? g_quark_to_string (identifier_quark) : "(NULL)");
+#endif
+
+              rec->identifier = identifier_quark;
+
+              for (list = rec->tags; list; list = g_list_next (list))
+                {
+                  gimp_tagged_add_tag (tagged, GIMP_TAG (list->data));
+                }
+
+              rec->referenced = TRUE;
+              return;
+            }
+        }
+    }
+
+}
+
+static void
+gimp_tag_cache_object_initialize (GimpTagged   *tagged,
+                                  GimpTagCache *cache)
+{
+  gimp_tag_cache_add_object (cache, tagged);
+}
+
+static void
+gimp_tag_cache_tagged_to_cache_record_foreach (GimpTagged  *tagged,
+                                               GList      **cache_records)
+{
+  gchar *identifier = gimp_tagged_get_identifier (tagged);
+
+  if (identifier)
+    {
+      GimpTagCacheRecord *cache_rec = g_new (GimpTagCacheRecord, 1);
+      gchar              *checksum;
+
+      checksum = gimp_tagged_get_checksum (tagged);
+
+      cache_rec->identifier = g_quark_from_string (identifier);
+      cache_rec->checksum   = g_quark_from_string (checksum);
+      cache_rec->tags       = g_list_copy (gimp_tagged_get_tags (tagged));
+
+      g_free (checksum);
+
+      *cache_records = g_list_prepend (*cache_records, cache_rec);
+    }
+
+  g_free (identifier);
+}
+
+/**
+ * gimp_tag_cache_save:
+ * @cache:      a GimpTagCache object.
+ *
+ * Saves tag cache to cache file.
+ **/
+void
+gimp_tag_cache_save (GimpTagCache *cache)
+{
+  GString       *buf;
+  GList         *saved_records;
+  GList         *iterator;
+  GFile         *file;
+  GOutputStream *output;
+  GError        *error = NULL;
+  gint           i;
+
+  g_return_if_fail (GIMP_IS_TAG_CACHE (cache));
+
+  saved_records = NULL;
+  for (i = 0; i < cache->priv->records->len; i++)
+    {
+      GimpTagCacheRecord *current_record = &g_array_index (cache->priv->records,
+                                                           GimpTagCacheRecord, i);
+
+      if (! current_record->referenced && current_record->tags)
+        {
+          /* keep tagged objects which have tags assigned
+           * but were not loaded.
+           */
+          GimpTagCacheRecord *record_copy = g_new (GimpTagCacheRecord, 1);
+
+          record_copy->identifier = current_record->identifier;
+          record_copy->checksum   = current_record->checksum;
+          record_copy->tags       = g_list_copy (current_record->tags);
+
+          saved_records = g_list_prepend (saved_records, record_copy);
+        }
+    }
+
+  for (iterator = cache->priv->containers;
+       iterator;
+       iterator = g_list_next (iterator))
+    {
+      gimp_container_foreach (GIMP_CONTAINER (iterator->data),
+                              (GFunc) gimp_tag_cache_tagged_to_cache_record_foreach,
+                              &saved_records);
+    }
+
+  saved_records = g_list_reverse (saved_records);
+
+  buf = g_string_new ("");
+  g_string_append (buf, "<?xml version='1.0' encoding='UTF-8'?>\n");
+  g_string_append (buf, "<tags>\n");
+
+  for (iterator = saved_records; iterator; iterator = g_list_next (iterator))
+    {
+      GimpTagCacheRecord *cache_rec = iterator->data;
+      GList              *tag_iterator;
+      gchar              *identifier_string;
+      gchar              *tag_string;
+
+      identifier_string = g_markup_escape_text (g_quark_to_string (cache_rec->identifier), -1);
+      g_string_append_printf (buf, "\n  <resource identifier=\"%s\" checksum=\"%s\">\n",
+                              identifier_string,
+                              g_quark_to_string (cache_rec->checksum));
+      g_free (identifier_string);
+
+      for (tag_iterator = cache_rec->tags;
+           tag_iterator;
+           tag_iterator = g_list_next (tag_iterator))
+        {
+          GimpTag *tag = GIMP_TAG (tag_iterator->data);
+
+          if (! gimp_tag_get_internal (tag))
+            {
+              tag_string = g_markup_escape_text (gimp_tag_get_name (tag), -1);
+              g_string_append_printf (buf, "    <tag>%s</tag>\n", tag_string);
+              g_free (tag_string);
+            }
+        }
+
+      g_string_append (buf, "  </resource>\n");
+    }
+
+  g_string_append (buf, "</tags>\n");
+
+  file = gimp_directory_file (GIMP_TAG_CACHE_FILE, NULL);
+
+  output = G_OUTPUT_STREAM (g_file_replace (file,
+                                            NULL, FALSE, G_FILE_CREATE_NONE,
+                                            NULL, &error));
+  if (! output)
+    {
+      g_printerr ("%s\n", error->message);
+    }
+  else if (! g_output_stream_write_all (output, buf->str, buf->len,
+                                        NULL, NULL, &error))
+    {
+      GCancellable *cancellable = g_cancellable_new ();
+
+      g_printerr (_("Error writing '%s': %s\n"),
+                  gimp_file_get_utf8_name (file), error->message);
+
+      /* Cancel the overwrite initiated by g_file_replace(). */
+      g_cancellable_cancel (cancellable);
+      g_output_stream_close (output, cancellable, NULL);
+      g_object_unref (cancellable);
+    }
+  else if (! g_output_stream_close (output, NULL, &error))
+    {
+      g_printerr (_("Error closing '%s': %s\n"),
+                  gimp_file_get_utf8_name (file), error->message);
+    }
+
+  if (output)
+    g_object_unref (output);
+
+  g_clear_error (&error);
+  g_object_unref (file);
+  g_string_free (buf, TRUE);
+
+  for (iterator = saved_records;
+       iterator;
+       iterator = g_list_next (iterator))
+    {
+      GimpTagCacheRecord *cache_rec = iterator->data;
+
+      g_list_free (cache_rec->tags);
+      g_free (cache_rec);
+    }
+
+  g_list_free (saved_records);
+}
+
+/**
+ * gimp_tag_cache_load:
+ * @cache:      a GimpTagCache object.
+ *
+ * Loads tag cache from file.
+ **/
+void
+gimp_tag_cache_load (GimpTagCache *cache)
+{
+  GFile                 *file;
+  GMarkupParser          markup_parser;
+  GimpXmlParser         *xml_parser;
+  GimpTagCacheParseData  parse_data;
+  GError                *error = NULL;
+
+  g_return_if_fail (GIMP_IS_TAG_CACHE (cache));
+
+  /* clear any previous priv->records */
+  cache->priv->records = g_array_set_size (cache->priv->records, 0);
+
+  parse_data.records = g_array_new (FALSE, FALSE, sizeof (GimpTagCacheRecord));
+  memset (&parse_data.current_record, 0, sizeof (GimpTagCacheRecord));
+
+  markup_parser.start_element = gimp_tag_cache_load_start_element;
+  markup_parser.end_element   = gimp_tag_cache_load_end_element;
+  markup_parser.text          = gimp_tag_cache_load_text;
+  markup_parser.passthrough   = NULL;
+  markup_parser.error         = gimp_tag_cache_load_error;
+
+  xml_parser = gimp_xml_parser_new (&markup_parser, &parse_data);
+
+  file = gimp_directory_file (GIMP_TAG_CACHE_FILE, NULL);
+
+  if (gimp_xml_parser_parse_gfile (xml_parser, file, &error))
+    {
+      cache->priv->records = g_array_append_vals (cache->priv->records,
+                                                  parse_data.records->data,
+                                                  parse_data.records->len);
+    }
+  else
+    {
+      g_printerr ("Failed to parse tag cache: %s\n",
+                  error ? error->message : "WTF unknown error");
+    }
+
+  g_object_unref (file);
+  gimp_xml_parser_free (xml_parser);
+  g_array_free (parse_data.records, TRUE);
+}
+
+static  void
+gimp_tag_cache_load_start_element (GMarkupParseContext *context,
+                                   const gchar         *element_name,
+                                   const gchar        **attribute_names,
+                                   const gchar        **attribute_values,
+                                   gpointer             user_data,
+                                   GError             **error)
+{
+  GimpTagCacheParseData *parse_data = user_data;
+
+  if (! strcmp (element_name, "resource"))
+    {
+      const gchar *identifier;
+      const gchar *checksum;
+
+      identifier = gimp_tag_cache_attribute_name_to_value (attribute_names,
+                                                           attribute_values,
+                                                           "identifier");
+      checksum   = gimp_tag_cache_attribute_name_to_value (attribute_names,
+                                                           attribute_values,
+                                                           "checksum");
+
+      if (! identifier)
+        {
+          g_set_error (error,
+                       gimp_tag_cache_get_error_domain (),
+                       1001,
+                       "Resource tag does not contain required attribute identifier.");
+          return;
+        }
+
+      memset (&parse_data->current_record, 0, sizeof (GimpTagCacheRecord));
+
+      parse_data->current_record.identifier = g_quark_from_string (identifier);
+      parse_data->current_record.checksum   = g_quark_from_string (checksum);
+    }
+}
+
+static void
+gimp_tag_cache_load_end_element (GMarkupParseContext *context,
+                                 const gchar         *element_name,
+                                 gpointer             user_data,
+                                 GError             **error)
+{
+  GimpTagCacheParseData *parse_data = user_data;
+
+  if (strcmp (element_name, "resource") == 0)
+    {
+      parse_data->records = g_array_append_val (parse_data->records,
+                                                parse_data->current_record);
+      memset (&parse_data->current_record, 0, sizeof (GimpTagCacheRecord));
+    }
+}
+
+static void
+gimp_tag_cache_load_text (GMarkupParseContext  *context,
+                          const gchar          *text,
+                          gsize                 text_len,
+                          gpointer              user_data,
+                          GError              **error)
+{
+  GimpTagCacheParseData *parse_data = user_data;
+  const gchar           *current_element;
+  gchar                  buffer[2048];
+  GimpTag               *tag;
+
+  current_element = g_markup_parse_context_get_element (context);
+
+  if (g_strcmp0 (current_element, "tag") == 0)
+    {
+      if (text_len >= sizeof (buffer))
+        {
+          g_set_error (error, gimp_tag_cache_get_error_domain (), 1002,
+                       "Tag value is too long.");
+          return;
+        }
+
+      memcpy (buffer, text, text_len);
+      buffer[text_len] = '\0';
+
+      tag = gimp_tag_new (buffer);
+      if (tag)
+        {
+          parse_data->current_record.tags = g_list_append (parse_data->current_record.tags,
+                                                           tag);
+        }
+      else
+        {
+          g_warning ("dropping invalid tag '%s' from '%s'\n", buffer,
+                     g_quark_to_string (parse_data->current_record.identifier));
+        }
+    }
+}
+
+static  void
+gimp_tag_cache_load_error (GMarkupParseContext *context,
+                           GError              *error,
+                           gpointer             user_data)
+{
+  g_printerr ("Tag cache parse error: %s\n", error->message);
+}
+
+static const gchar*
+gimp_tag_cache_attribute_name_to_value (const gchar **attribute_names,
+                                        const gchar **attribute_values,
+                                        const gchar  *name)
+{
+  while (*attribute_names)
+    {
+      if (! strcmp (*attribute_names, name))
+        {
+          return *attribute_values;
+        }
+
+      attribute_names++;
+      attribute_values++;
+    }
+
+  return NULL;
+}
+
+static GQuark
+gimp_tag_cache_get_error_domain (void)
+{
+  return g_quark_from_static_string ("gimp-tag-cache-error-quark");
+}
diff --git a/app/core/gimptagcache.h b/app/core/gimptagcache.h
new file mode 100644
index 0000000..4c3a465
--- /dev/null
+++ b/app/core/gimptagcache.h
@@ -0,0 +1,63 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimptagcache.h
+ * Copyright (C) 2008 Aurimas Juška <aurisj@svn.gnome.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_TAG_CACHE_H__
+#define __GIMP_TAG_CACHE_H__
+
+
+#include "gimpobject.h"
+
+
+#define GIMP_TYPE_TAG_CACHE            (gimp_tag_cache_get_type ())
+#define GIMP_TAG_CACHE(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_TAG_CACHE, GimpTagCache))
+#define GIMP_TAG_CACHE_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_TAG_CACHE, GimpTagCacheClass))
+#define GIMP_IS_TAG_CACHE(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_TAG_CACHE))
+#define GIMP_IS_TAG_CACHE_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_TAG_CACHE))
+#define GIMP_TAG_CACHE_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_TAG_CACHE, GimpTagCacheClass))
+
+
+typedef struct _GimpTagCacheClass   GimpTagCacheClass;
+typedef struct _GimpTagCachePrivate GimpTagCachePrivate;
+
+struct _GimpTagCache
+{
+  GimpObject           parent_instance;
+
+  GimpTagCachePrivate *priv;
+};
+
+struct _GimpTagCacheClass
+{
+  GimpObjectClass  parent_class;
+};
+
+
+GType           gimp_tag_cache_get_type      (void) G_GNUC_CONST;
+
+GimpTagCache *  gimp_tag_cache_new           (void);
+
+void            gimp_tag_cache_save          (GimpTagCache  *cache);
+void            gimp_tag_cache_load          (GimpTagCache  *cache);
+
+void            gimp_tag_cache_add_container (GimpTagCache  *cache,
+                                              GimpContainer *container);
+
+
+#endif  /*  __GIMP_TAG_CACHE_H__  */
diff --git a/app/core/gimptagged.c b/app/core/gimptagged.c
new file mode 100644
index 0000000..7875f9a
--- /dev/null
+++ b/app/core/gimptagged.c
@@ -0,0 +1,260 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimptagged.c
+ * Copyright (C) 2008  Sven Neumann <sven@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <glib-object.h>
+
+#include "core-types.h"
+
+#include "gimpmarshal.h"
+#include "gimptag.h"
+#include "gimptagged.h"
+
+
+enum
+{
+  TAG_ADDED,
+  TAG_REMOVED,
+  LAST_SIGNAL
+};
+
+
+G_DEFINE_INTERFACE (GimpTagged, gimp_tagged, G_TYPE_OBJECT)
+
+
+static guint gimp_tagged_signals[LAST_SIGNAL] = { 0, };
+
+
+/*  private functions  */
+
+
+static void
+gimp_tagged_default_init (GimpTaggedInterface *iface)
+{
+  gimp_tagged_signals[TAG_ADDED] =
+    g_signal_new ("tag-added",
+                  GIMP_TYPE_TAGGED,
+                  G_SIGNAL_RUN_LAST,
+                  G_STRUCT_OFFSET (GimpTaggedInterface, tag_added),
+                  NULL, NULL,
+                  g_cclosure_marshal_VOID__OBJECT,
+                  G_TYPE_NONE, 1,
+                  GIMP_TYPE_TAG);
+
+  gimp_tagged_signals[TAG_REMOVED] =
+    g_signal_new ("tag-removed",
+                  GIMP_TYPE_TAGGED,
+                  G_SIGNAL_RUN_LAST,
+                  G_STRUCT_OFFSET (GimpTaggedInterface, tag_removed),
+                  NULL, NULL,
+                  g_cclosure_marshal_VOID__OBJECT,
+                  G_TYPE_NONE, 1,
+                  GIMP_TYPE_TAG);
+}
+
+
+/*  public functions  */
+
+
+/**
+ * gimp_tagged_add_tag:
+ * @tagged: an object that implements the %GimpTagged interface
+ * @tag:    a %GimpTag
+ *
+ * Adds @tag to the @tagged object. The GimpTagged::tag-added signal
+ * is emitted if and only if the @tag was not already assigned to this
+ * object.
+ **/
+void
+gimp_tagged_add_tag (GimpTagged *tagged,
+                     GimpTag    *tag)
+{
+  g_return_if_fail (GIMP_IS_TAGGED (tagged));
+  g_return_if_fail (GIMP_IS_TAG (tag));
+
+  if (GIMP_TAGGED_GET_INTERFACE (tagged)->add_tag (tagged, tag))
+    {
+      g_signal_emit (tagged, gimp_tagged_signals[TAG_ADDED], 0, tag);
+    }
+}
+
+/**
+ * gimp_tagged_remove_tag:
+ * @tagged: an object that implements the %GimpTagged interface
+ * @tag:    a %GimpTag
+ *
+ * Removes @tag from the @tagged object. The GimpTagged::tag-removed
+ * signal is emitted if and only if the @tag was actually assigned to
+ * this object.
+ **/
+void
+gimp_tagged_remove_tag (GimpTagged *tagged,
+                        GimpTag    *tag)
+{
+  GList *tag_iter;
+
+  g_return_if_fail (GIMP_IS_TAGGED (tagged));
+  g_return_if_fail (GIMP_IS_TAG (tag));
+
+  for (tag_iter = gimp_tagged_get_tags (tagged);
+       tag_iter;
+       tag_iter = g_list_next (tag_iter))
+    {
+      GimpTag *tag_ref = tag_iter->data;
+
+      if (gimp_tag_equals (tag_ref, tag))
+        {
+          g_object_ref (tag_ref);
+
+          if (GIMP_TAGGED_GET_INTERFACE (tagged)->remove_tag (tagged, tag_ref))
+            {
+              g_signal_emit (tagged, gimp_tagged_signals[TAG_REMOVED], 0,
+                             tag_ref);
+            }
+
+          g_object_unref (tag_ref);
+
+          return;
+        }
+    }
+}
+
+/**
+ * gimp_tagged_set_tags:
+ * @tagged: an object that implements the %GimpTagged interface
+ * @tags:   a list of tags
+ *
+ * Sets the list of tags assigned to this object. The passed list of
+ * tags is copied and should be freed by the caller.
+ **/
+void
+gimp_tagged_set_tags (GimpTagged *tagged,
+                      GList      *tags)
+{
+  GList *old_tags;
+  GList *list;
+
+  g_return_if_fail (GIMP_IS_TAGGED (tagged));
+
+  old_tags = g_list_copy (gimp_tagged_get_tags (tagged));
+
+  for (list = old_tags; list; list = g_list_next (list))
+    {
+      gimp_tagged_remove_tag (tagged, list->data);
+    }
+
+  g_list_free (old_tags);
+
+  for (list = tags; list; list = g_list_next (list))
+    {
+      g_return_if_fail (GIMP_IS_TAG (list->data));
+
+      gimp_tagged_add_tag (tagged, list->data);
+    }
+}
+
+/**
+ * gimp_tagged_get_tags:
+ * @tagged: an object that implements the %GimpTagged interface
+ *
+ * Returns the list of tags assigned to this object. The returned %GList
+ * is owned by the @tagged object and must not be modified or destroyed.
+ *
+ * Return value: a list of tags
+ **/
+GList *
+gimp_tagged_get_tags (GimpTagged *tagged)
+{
+  g_return_val_if_fail (GIMP_IS_TAGGED (tagged), NULL);
+
+  return GIMP_TAGGED_GET_INTERFACE (tagged)->get_tags (tagged);
+}
+
+/**
+ * gimp_tagged_get_identifier:
+ * @tagged: an object that implements the %GimpTagged interface
+ *
+ * Returns an identifier string which uniquely identifies the tagged
+ * object. Two different objects must have unique identifiers but may
+ * have the same checksum (which will be the case if one object is a
+ * copy of the other). The identifier must be the same across
+ * sessions, so for example an instance pointer cannot be used as an
+ * identifier.
+ *
+ * Return value: a newly allocated string containing unique identifier
+ * of the object. It must be freed using #g_free.
+ **/
+gchar *
+gimp_tagged_get_identifier (GimpTagged *tagged)
+{
+  g_return_val_if_fail (GIMP_IS_TAGGED (tagged), NULL);
+
+  return GIMP_TAGGED_GET_INTERFACE (tagged)->get_identifier (tagged);
+}
+
+/**
+ * gimp_tagged_get_checksum:
+ * @tagged: an object that implements the %GimpTagged interface
+ *
+ * Returns the checksum of the @tagged object. It is used to remap the
+ * tags for an object for which the identifier has changed, for
+ * example if the user has renamed a data file since the last session.
+ *
+ * If the object does not want to support such remapping (objects not
+ * stored in file for example) it can return #NULL.
+ *
+ * Return value: checksum string if object needs identifier remapping,
+ * #NULL otherwise. Returned string must be freed with #g_free().
+ **/
+gchar *
+gimp_tagged_get_checksum (GimpTagged *tagged)
+{
+  g_return_val_if_fail (GIMP_IS_TAGGED (tagged), FALSE);
+
+  return GIMP_TAGGED_GET_INTERFACE (tagged)->get_checksum (tagged);
+}
+
+/**
+ * gimp_tagged_has_tag:
+ * @tagged: an object that implements the %GimpTagged interface
+ * @tag:    a %GimpTag
+ *
+ * Return value: #TRUE if the object has @tag, #FALSE otherwise.
+ **/
+gboolean
+gimp_tagged_has_tag (GimpTagged *tagged,
+                     GimpTag    *tag)
+{
+  GList *tag_iter;
+
+  g_return_val_if_fail (GIMP_IS_TAGGED (tagged), FALSE);
+  g_return_val_if_fail (GIMP_IS_TAG (tag), FALSE);
+
+  for (tag_iter = gimp_tagged_get_tags (tagged);
+       tag_iter;
+       tag_iter = g_list_next (tag_iter))
+    {
+      if (gimp_tag_equals (tag_iter->data, tag))
+        return TRUE;
+    }
+
+  return FALSE;
+}
diff --git a/app/core/gimptagged.h b/app/core/gimptagged.h
new file mode 100644
index 0000000..32251e9
--- /dev/null
+++ b/app/core/gimptagged.h
@@ -0,0 +1,72 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1997 Spencer Kimball and Peter Mattis
+ *
+ * gimptagged.h
+ * Copyright (C) 2008  Sven Neumann <sven@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_TAGGED_H__
+#define __GIMP_TAGGED_H__
+
+
+#define GIMP_TYPE_TAGGED               (gimp_tagged_get_type ())
+#define GIMP_IS_TAGGED(obj)            (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_TAGGED))
+#define GIMP_TAGGED(obj)               (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_TAGGED, GimpTagged))
+#define GIMP_TAGGED_GET_INTERFACE(obj) (G_TYPE_INSTANCE_GET_INTERFACE ((obj), GIMP_TYPE_TAGGED, GimpTaggedInterface))
+
+
+typedef struct _GimpTaggedInterface GimpTaggedInterface;
+
+struct _GimpTaggedInterface
+{
+  GTypeInterface base_iface;
+
+  /*  signals            */
+  void       (* tag_added)      (GimpTagged *tagged,
+                                 GimpTag    *tag);
+  void       (* tag_removed)    (GimpTagged *tagged,
+                                 GimpTag    *tag);
+
+  /*  virtual functions  */
+  gboolean   (* add_tag)        (GimpTagged *tagged,
+                                 GimpTag    *tag);
+  gboolean   (* remove_tag)     (GimpTagged *tagged,
+                                 GimpTag    *tag);
+  GList    * (* get_tags)       (GimpTagged *tagged);
+  gchar    * (* get_identifier) (GimpTagged *tagged);
+  gchar    * (* get_checksum)   (GimpTagged *tagged);
+};
+
+
+GType      gimp_tagged_get_type       (void) G_GNUC_CONST;
+
+void       gimp_tagged_add_tag        (GimpTagged *tagged,
+                                       GimpTag    *tag);
+void       gimp_tagged_remove_tag     (GimpTagged *tagged,
+                                       GimpTag    *tag);
+
+void       gimp_tagged_set_tags       (GimpTagged *tagged,
+                                       GList      *tags);
+GList    * gimp_tagged_get_tags       (GimpTagged *tagged);
+
+gchar    * gimp_tagged_get_identifier (GimpTagged *tagged);
+gchar    * gimp_tagged_get_checksum   (GimpTagged *tagged);
+
+gboolean   gimp_tagged_has_tag        (GimpTagged *tagged,
+                                       GimpTag    *tag);
+
+
+#endif  /* __GIMP_TAGGED_H__ */
diff --git a/app/core/gimptaggedcontainer.c b/app/core/gimptaggedcontainer.c
new file mode 100644
index 0000000..93ea58b
--- /dev/null
+++ b/app/core/gimptaggedcontainer.c
@@ -0,0 +1,483 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1997 Spencer Kimball and Peter Mattis
+ *
+ * gimptaggedcontainer.c
+ * Copyright (C) 2008 Aurimas Juška <aurisj@svn.gnome.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gio/gio.h>
+
+#include "core-types.h"
+
+#include "gimp.h"
+#include "gimpmarshal.h"
+#include "gimptag.h"
+#include "gimptagged.h"
+#include "gimptaggedcontainer.h"
+
+
+enum
+{
+  TAG_COUNT_CHANGED,
+  LAST_SIGNAL
+};
+
+
+static void      gimp_tagged_container_dispose            (GObject               *object);
+static gint64    gimp_tagged_container_get_memsize        (GimpObject            *object,
+                                                           gint64                *gui_size);
+
+static void      gimp_tagged_container_clear              (GimpContainer         *container);
+
+static void      gimp_tagged_container_src_add            (GimpFilteredContainer *filtered_container,
+                                                           GimpObject            *object);
+static void      gimp_tagged_container_src_remove         (GimpFilteredContainer *filtered_container,
+                                                           GimpObject            *object);
+static void      gimp_tagged_container_src_freeze         (GimpFilteredContainer *filtered_container);
+static void      gimp_tagged_container_src_thaw           (GimpFilteredContainer *filtered_container);
+
+static gboolean  gimp_tagged_container_object_matches     (GimpTaggedContainer   *tagged_container,
+                                                           GimpObject            *object);
+
+static void      gimp_tagged_container_tag_added          (GimpTagged            *tagged,
+                                                           GimpTag               *tag,
+                                                           GimpTaggedContainer   *tagged_container);
+static void      gimp_tagged_container_tag_removed        (GimpTagged            *tagged,
+                                                           GimpTag               *tag,
+                                                           GimpTaggedContainer   *tagged_container);
+static void      gimp_tagged_container_ref_tag            (GimpTaggedContainer   *tagged_container,
+                                                           GimpTag               *tag);
+static void      gimp_tagged_container_unref_tag          (GimpTaggedContainer   *tagged_container,
+                                                           GimpTag               *tag);
+static void      gimp_tagged_container_tag_count_changed  (GimpTaggedContainer   *tagged_container,
+                                                           gint                   tag_count);
+
+
+G_DEFINE_TYPE (GimpTaggedContainer, gimp_tagged_container,
+               GIMP_TYPE_FILTERED_CONTAINER)
+
+#define parent_class gimp_tagged_container_parent_class
+
+static guint gimp_tagged_container_signals[LAST_SIGNAL] = { 0, };
+
+
+static void
+gimp_tagged_container_class_init (GimpTaggedContainerClass *klass)
+{
+  GObjectClass               *g_object_class    = G_OBJECT_CLASS (klass);
+  GimpObjectClass            *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+  GimpContainerClass         *container_class   = GIMP_CONTAINER_CLASS (klass);
+  GimpFilteredContainerClass *filtered_class    = GIMP_FILTERED_CONTAINER_CLASS (klass);
+
+  g_object_class->dispose        = gimp_tagged_container_dispose;
+
+  gimp_object_class->get_memsize = gimp_tagged_container_get_memsize;
+
+  container_class->clear         = gimp_tagged_container_clear;
+
+  filtered_class->src_add        = gimp_tagged_container_src_add;
+  filtered_class->src_remove     = gimp_tagged_container_src_remove;
+  filtered_class->src_freeze     = gimp_tagged_container_src_freeze;
+  filtered_class->src_thaw       = gimp_tagged_container_src_thaw;
+
+  klass->tag_count_changed       = gimp_tagged_container_tag_count_changed;
+
+  gimp_tagged_container_signals[TAG_COUNT_CHANGED] =
+    g_signal_new ("tag-count-changed",
+                  GIMP_TYPE_TAGGED_CONTAINER,
+                  G_SIGNAL_RUN_LAST,
+                  G_STRUCT_OFFSET (GimpTaggedContainerClass, tag_count_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__INT,
+                  G_TYPE_NONE, 1,
+                  G_TYPE_INT);
+}
+
+static void
+gimp_tagged_container_init (GimpTaggedContainer *tagged_container)
+{
+  tagged_container->tag_ref_counts =
+    g_hash_table_new_full ((GHashFunc) gimp_tag_get_hash,
+                           (GEqualFunc) gimp_tag_equals,
+                           (GDestroyNotify) g_object_unref,
+                           (GDestroyNotify) NULL);
+}
+
+static void
+gimp_tagged_container_dispose (GObject *object)
+{
+  GimpTaggedContainer *tagged_container = GIMP_TAGGED_CONTAINER (object);
+
+  if (tagged_container->filter)
+    {
+      g_list_free_full (tagged_container->filter,
+                        (GDestroyNotify) gimp_tag_or_null_unref);
+      tagged_container->filter = NULL;
+    }
+
+  g_clear_pointer (&tagged_container->tag_ref_counts, g_hash_table_unref);
+
+  G_OBJECT_CLASS (parent_class)->dispose (object);
+}
+
+static gint64
+gimp_tagged_container_get_memsize (GimpObject *object,
+                                   gint64     *gui_size)
+{
+  gint64 memsize = 0;
+
+  /* FIXME take members into account */
+
+  return memsize + GIMP_OBJECT_CLASS (parent_class)->get_memsize (object,
+                                                                  gui_size);
+}
+
+static void
+gimp_tagged_container_clear (GimpContainer *container)
+{
+  GimpFilteredContainer *filtered_container = GIMP_FILTERED_CONTAINER (container);
+  GimpTaggedContainer   *tagged_container   = GIMP_TAGGED_CONTAINER (container);
+  GList                 *list;
+
+  for (list = GIMP_LIST (filtered_container->src_container)->queue->head;
+       list;
+       list = g_list_next (list))
+    {
+      g_signal_handlers_disconnect_by_func (list->data,
+                                            gimp_tagged_container_tag_added,
+                                            tagged_container);
+      g_signal_handlers_disconnect_by_func (list->data,
+                                            gimp_tagged_container_tag_removed,
+                                            tagged_container);
+    }
+
+  if (tagged_container->tag_ref_counts)
+    {
+      g_hash_table_remove_all (tagged_container->tag_ref_counts);
+      tagged_container->tag_count = 0;
+    }
+
+  GIMP_CONTAINER_CLASS (parent_class)->clear (container);
+}
+
+static void
+gimp_tagged_container_src_add (GimpFilteredContainer *filtered_container,
+                               GimpObject            *object)
+{
+  GimpTaggedContainer *tagged_container = GIMP_TAGGED_CONTAINER (filtered_container);
+  GList               *list;
+
+  for (list = gimp_tagged_get_tags (GIMP_TAGGED (object));
+       list;
+       list = g_list_next (list))
+    {
+      gimp_tagged_container_ref_tag (tagged_container, list->data);
+    }
+
+  g_signal_connect (object, "tag-added",
+                    G_CALLBACK (gimp_tagged_container_tag_added),
+                    tagged_container);
+  g_signal_connect (object, "tag-removed",
+                    G_CALLBACK (gimp_tagged_container_tag_removed),
+                    tagged_container);
+
+  if (gimp_tagged_container_object_matches (tagged_container, object))
+    {
+      gimp_container_add (GIMP_CONTAINER (tagged_container), object);
+    }
+}
+
+static void
+gimp_tagged_container_src_remove (GimpFilteredContainer *filtered_container,
+                                  GimpObject            *object)
+{
+  GimpTaggedContainer *tagged_container = GIMP_TAGGED_CONTAINER (filtered_container);
+  GList               *list;
+
+  g_signal_handlers_disconnect_by_func (object,
+                                        gimp_tagged_container_tag_added,
+                                        tagged_container);
+  g_signal_handlers_disconnect_by_func (object,
+                                        gimp_tagged_container_tag_removed,
+                                        tagged_container);
+
+  for (list = gimp_tagged_get_tags (GIMP_TAGGED (object));
+       list;
+       list = g_list_next (list))
+    {
+      gimp_tagged_container_unref_tag (tagged_container, list->data);
+    }
+
+  if (gimp_tagged_container_object_matches (tagged_container, object))
+    {
+      gimp_container_remove (GIMP_CONTAINER (tagged_container), object);
+    }
+}
+
+static void
+gimp_tagged_container_src_freeze (GimpFilteredContainer *filtered_container)
+{
+  gimp_container_clear (GIMP_CONTAINER (filtered_container));
+}
+
+static void
+gimp_tagged_container_src_thaw (GimpFilteredContainer *filtered_container)
+{
+  GList *list;
+
+  for (list = GIMP_LIST (filtered_container->src_container)->queue->head;
+       list;
+       list = g_list_next (list))
+    {
+      gimp_tagged_container_src_add (filtered_container, list->data);
+    }
+}
+
+/**
+ * gimp_tagged_container_new:
+ * @src_container: container to be filtered.
+ *
+ * Creates a new #GimpTaggedContainer object which creates filtered
+ * data view of #GimpTagged objects. It filters @src_container for
+ * objects containing all of the filtering tags. Synchronization with
+ * @src_container data is performed automatically.
+ *
+ * Return value: a new #GimpTaggedContainer object.
+ **/
+GimpContainer *
+gimp_tagged_container_new (GimpContainer *src_container)
+{
+  GimpTaggedContainer *tagged_container;
+  GType                children_type;
+  GCompareFunc         sort_func;
+
+  g_return_val_if_fail (GIMP_IS_LIST (src_container), NULL);
+
+  children_type = gimp_container_get_children_type (src_container);
+  sort_func     = GIMP_LIST (src_container)->sort_func;
+
+  tagged_container = g_object_new (GIMP_TYPE_TAGGED_CONTAINER,
+                                   "sort-func",     sort_func,
+                                   "children-type", children_type,
+                                   "policy",        GIMP_CONTAINER_POLICY_WEAK,
+                                   "unique-names",  FALSE,
+                                   "src-container", src_container,
+                                   NULL);
+
+  return GIMP_CONTAINER (tagged_container);
+}
+
+/**
+ * gimp_tagged_container_set_filter:
+ * @tagged_container: a #GimpTaggedContainer object.
+ * @tags:             list of #GimpTag objects.
+ *
+ * Sets list of tags to be used for filtering. Only objects which have
+ * all of the tags assigned match filtering criteria.
+ **/
+void
+gimp_tagged_container_set_filter (GimpTaggedContainer *tagged_container,
+                                  GList               *tags)
+{
+  GList *new_filter;
+
+  g_return_if_fail (GIMP_IS_TAGGED_CONTAINER (tagged_container));
+
+  if (tags)
+    {
+      GList *list;
+
+      for (list = tags; list; list = g_list_next (list))
+        g_return_if_fail (list->data == NULL || GIMP_IS_TAG (list->data));
+    }
+
+  if (! gimp_container_frozen (GIMP_FILTERED_CONTAINER (tagged_container)->src_container))
+    {
+      gimp_tagged_container_src_freeze (GIMP_FILTERED_CONTAINER (tagged_container));
+    }
+
+  /*  ref new tags first, they could be the same as the old ones  */
+  new_filter = g_list_copy (tags);
+  g_list_foreach (new_filter, (GFunc) gimp_tag_or_null_ref, NULL);
+
+  g_list_free_full (tagged_container->filter,
+                    (GDestroyNotify) gimp_tag_or_null_unref);
+  tagged_container->filter = new_filter;
+
+  if (! gimp_container_frozen (GIMP_FILTERED_CONTAINER (tagged_container)->src_container))
+    {
+      gimp_tagged_container_src_thaw (GIMP_FILTERED_CONTAINER (tagged_container));
+    }
+}
+
+/**
+ * gimp_tagged_container_get_filter:
+ * @tagged_container: a #GimpTaggedContainer object.
+ *
+ * Returns current tag filter. Tag filter is a list of GimpTag objects, which
+ * must be contained by each object matching filter criteria.
+ *
+ * Return value: a list of GimpTag objects used as filter. This value should
+ *               not be modified or freed.
+ **/
+const GList *
+gimp_tagged_container_get_filter (GimpTaggedContainer *tagged_container)
+{
+  g_return_val_if_fail (GIMP_IS_TAGGED_CONTAINER (tagged_container), NULL);
+
+  return tagged_container->filter;
+}
+
+static gboolean
+gimp_tagged_container_object_matches (GimpTaggedContainer *tagged_container,
+                                      GimpObject          *object)
+{
+  GList *filter_tags;
+
+  for (filter_tags = tagged_container->filter;
+       filter_tags;
+       filter_tags = g_list_next (filter_tags))
+    {
+      if (! filter_tags->data)
+        {
+          /* invalid tag - does not match */
+          return FALSE;
+        }
+
+      if (! gimp_tagged_has_tag (GIMP_TAGGED (object),
+                                 filter_tags->data))
+        {
+          /* match for the tag was not found.
+           * since query is of type AND, it whole fails.
+           */
+          return FALSE;
+        }
+    }
+
+  return TRUE;
+}
+
+static void
+gimp_tagged_container_tag_added (GimpTagged          *tagged,
+                                 GimpTag             *tag,
+                                 GimpTaggedContainer *tagged_container)
+{
+  gimp_tagged_container_ref_tag (tagged_container, tag);
+
+  if (gimp_tagged_container_object_matches (tagged_container,
+                                            GIMP_OBJECT (tagged)) &&
+      ! gimp_container_have (GIMP_CONTAINER (tagged_container),
+                             GIMP_OBJECT (tagged)))
+    {
+      gimp_container_add (GIMP_CONTAINER (tagged_container),
+                          GIMP_OBJECT (tagged));
+    }
+}
+
+static void
+gimp_tagged_container_tag_removed (GimpTagged          *tagged,
+                                   GimpTag             *tag,
+                                   GimpTaggedContainer *tagged_container)
+{
+  gimp_tagged_container_unref_tag (tagged_container, tag);
+
+  if (! gimp_tagged_container_object_matches (tagged_container,
+                                              GIMP_OBJECT (tagged)) &&
+      gimp_container_have (GIMP_CONTAINER (tagged_container),
+                           GIMP_OBJECT (tagged)))
+    {
+      gimp_container_remove (GIMP_CONTAINER (tagged_container),
+                             GIMP_OBJECT (tagged));
+    }
+}
+
+static void
+gimp_tagged_container_ref_tag (GimpTaggedContainer *tagged_container,
+                               GimpTag             *tag)
+{
+  gint ref_count;
+
+  ref_count = GPOINTER_TO_INT (g_hash_table_lookup (tagged_container->tag_ref_counts,
+                                                    tag));
+  ref_count++;
+  g_hash_table_insert (tagged_container->tag_ref_counts,
+                       g_object_ref (tag),
+                       GINT_TO_POINTER (ref_count));
+
+  if (ref_count == 1)
+    {
+      tagged_container->tag_count++;
+      g_signal_emit (tagged_container,
+                     gimp_tagged_container_signals[TAG_COUNT_CHANGED], 0,
+                     tagged_container->tag_count);
+    }
+}
+
+static void
+gimp_tagged_container_unref_tag (GimpTaggedContainer *tagged_container,
+                                 GimpTag             *tag)
+{
+  gint ref_count;
+
+  ref_count = GPOINTER_TO_INT (g_hash_table_lookup (tagged_container->tag_ref_counts,
+                                                    tag));
+  ref_count--;
+
+  if (ref_count > 0)
+    {
+      g_hash_table_insert (tagged_container->tag_ref_counts,
+                           g_object_ref (tag),
+                           GINT_TO_POINTER (ref_count));
+    }
+  else
+    {
+      if (g_hash_table_remove (tagged_container->tag_ref_counts, tag))
+        {
+          tagged_container->tag_count--;
+          g_signal_emit (tagged_container,
+                         gimp_tagged_container_signals[TAG_COUNT_CHANGED], 0,
+                         tagged_container->tag_count);
+        }
+    }
+}
+
+static void
+gimp_tagged_container_tag_count_changed (GimpTaggedContainer *container,
+                                         gint                 tag_count)
+{
+}
+
+/**
+ * gimp_tagged_container_get_tag_count:
+ * @container:  a #GimpTaggedContainer object.
+ *
+ * Get number of distinct tags that are currently assigned to all
+ * objects in the container. The count is independent of currently
+ * used filter, it is provided for all available objects (ie. empty
+ * filter).
+ *
+ * Return value: number of distinct tags assigned to all objects in the
+ *               container.
+ **/
+gint
+gimp_tagged_container_get_tag_count (GimpTaggedContainer *container)
+{
+  g_return_val_if_fail (GIMP_IS_TAGGED_CONTAINER (container), 0);
+
+  return container->tag_count;
+}
diff --git a/app/core/gimptaggedcontainer.h b/app/core/gimptaggedcontainer.h
new file mode 100644
index 0000000..02beeeb
--- /dev/null
+++ b/app/core/gimptaggedcontainer.h
@@ -0,0 +1,67 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1997 Spencer Kimball and Peter Mattis
+ *
+ * gimptaggedcontainer.h
+ * Copyright (C) 2008 Aurimas Juška <aurisj@svn.gnome.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_TAGGED_CONTAINER_H__
+#define __GIMP_TAGGED_CONTAINER_H__
+
+
+#include "gimpfilteredcontainer.h"
+
+
+#define GIMP_TYPE_TAGGED_CONTAINER            (gimp_tagged_container_get_type ())
+#define GIMP_TAGGED_CONTAINER(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_TAGGED_CONTAINER, GimpTaggedContainer))
+#define GIMP_TAGGED_CONTAINER_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_TAGGED_CONTAINER, GimpTaggedContainerClass))
+#define GIMP_IS_TAGGED_CONTAINER(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_TAGGED_CONTAINER))
+#define GIMP_IS_TAGGED_CONTAINER_CLASS(class) (G_TYPE_CHECK_CLASS_TYPE ((class), GIMP_TYPE_TAGGED_CONTAINER))
+#define GIMP_TAGGED_CONTAINER_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_TAGGED_CONTAINER, GimpTaggedContainerClass))
+
+
+typedef struct _GimpTaggedContainerClass GimpTaggedContainerClass;
+
+struct _GimpTaggedContainer
+{
+  GimpFilteredContainer  parent_instance;
+
+  GList                 *filter;
+  GHashTable            *tag_ref_counts;
+  gint                   tag_count;
+};
+
+struct _GimpTaggedContainerClass
+{
+  GimpFilteredContainerClass  parent_class;
+
+  void (* tag_count_changed) (GimpTaggedContainer *container,
+                              gint                 count);
+};
+
+
+GType           gimp_tagged_container_get_type      (void) G_GNUC_CONST;
+
+GimpContainer * gimp_tagged_container_new           (GimpContainer       *src_container);
+
+void            gimp_tagged_container_set_filter    (GimpTaggedContainer *tagged_container,
+                                                     GList               *tags);
+const GList   * gimp_tagged_container_get_filter    (GimpTaggedContainer *tagged_container);
+
+gint            gimp_tagged_container_get_tag_count (GimpTaggedContainer *container);
+
+
+#endif  /* __GIMP_TAGGED_CONTAINER_H__ */
diff --git a/app/core/gimptempbuf.c b/app/core/gimptempbuf.c
new file mode 100644
index 0000000..2879be9
--- /dev/null
+++ b/app/core/gimptempbuf.c
@@ -0,0 +1,450 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <cairo.h>
+#include <gegl.h>
+#include <gegl-utils.h>
+#include <glib/gstdio.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+#include "core-types.h"
+
+#include "libgimpcolor/gimpcolor.h"
+
+#include "gimptempbuf.h"
+
+
+#define LOCK_DATA_ALIGNMENT 16
+
+
+struct _GimpTempBuf
+{
+  gint        ref_count;
+  gint        width;
+  gint        height;
+  const Babl *format;
+  guchar     *data;
+};
+
+typedef struct
+{
+  const Babl     *format;
+  GeglAccessMode  access_mode;
+} LockData;
+
+G_STATIC_ASSERT (sizeof (LockData) <= LOCK_DATA_ALIGNMENT);
+
+
+/*  local variables  */
+
+static guintptr gimp_temp_buf_total_memsize = 0;
+
+
+/*  public functions  */
+
+GimpTempBuf *
+gimp_temp_buf_new (gint        width,
+                   gint        height,
+                   const Babl *format)
+{
+  GimpTempBuf *temp;
+  gint         bpp;
+
+  g_return_val_if_fail (format != NULL, NULL);
+
+  bpp = babl_format_get_bytes_per_pixel (format);
+
+  g_return_val_if_fail (width > 0 && height > 0 && bpp > 0, NULL);
+  g_return_val_if_fail (G_MAXSIZE / width / height / bpp > 0, NULL);
+
+  temp = g_slice_new (GimpTempBuf);
+
+  temp->ref_count = 1;
+  temp->width     = width;
+  temp->height    = height;
+  temp->format    = format;
+  temp->data      = gegl_malloc ((gsize) width * height * bpp);
+
+  g_atomic_pointer_add (&gimp_temp_buf_total_memsize,
+                        +gimp_temp_buf_get_memsize (temp));
+
+  return temp;
+}
+
+GimpTempBuf *
+gimp_temp_buf_new_from_pixbuf (GdkPixbuf  *pixbuf,
+                               const Babl *f_or_null)
+{
+  const Babl   *format = f_or_null;
+  const Babl   *fish   = NULL;
+  GimpTempBuf  *temp_buf;
+  const guchar *pixels;
+  gint          width;
+  gint          height;
+  gint          rowstride;
+  gint          bpp;
+  guchar       *data;
+  gint          i;
+
+  g_return_val_if_fail (GDK_IS_PIXBUF (pixbuf), NULL);
+
+  if (! format)
+    format = gimp_pixbuf_get_format (pixbuf);
+
+  pixels    = gdk_pixbuf_get_pixels (pixbuf);
+  width     = gdk_pixbuf_get_width (pixbuf);
+  height    = gdk_pixbuf_get_height (pixbuf);
+  rowstride = gdk_pixbuf_get_rowstride (pixbuf);
+
+  temp_buf  = gimp_temp_buf_new (width, height, format);
+  data      = gimp_temp_buf_get_data (temp_buf);
+
+  bpp       = babl_format_get_bytes_per_pixel (format);
+
+  if (gimp_pixbuf_get_format (pixbuf) != format)
+    fish = babl_fish (gimp_pixbuf_get_format (pixbuf), format);
+
+  for (i = 0; i < height; i++)
+    {
+      if (fish)
+        babl_process (fish, pixels, data, width);
+      else
+        memcpy (data, pixels, width * bpp);
+
+      data   += width * bpp;
+      pixels += rowstride;
+    }
+
+  return temp_buf;
+}
+
+GimpTempBuf *
+gimp_temp_buf_copy (const GimpTempBuf *src)
+{
+  GimpTempBuf *dest;
+
+  g_return_val_if_fail (src != NULL, NULL);
+
+  dest = gimp_temp_buf_new (src->width, src->height, src->format);
+
+  memcpy (gimp_temp_buf_get_data (dest),
+          gimp_temp_buf_get_data (src),
+          gimp_temp_buf_get_data_size (src));
+
+  return dest;
+}
+
+GimpTempBuf *
+gimp_temp_buf_ref (const GimpTempBuf *buf)
+{
+  g_return_val_if_fail (buf != NULL, NULL);
+
+  g_atomic_int_inc ((gint *) &buf->ref_count);
+
+  return (GimpTempBuf *) buf;
+}
+
+void
+gimp_temp_buf_unref (const GimpTempBuf *buf)
+{
+  g_return_if_fail (buf != NULL);
+  g_return_if_fail (buf->ref_count > 0);
+
+  if (g_atomic_int_dec_and_test ((gint *) &buf->ref_count))
+    {
+      g_atomic_pointer_add (&gimp_temp_buf_total_memsize,
+                            -gimp_temp_buf_get_memsize (buf));
+
+
+      if (buf->data)
+        gegl_free (buf->data);
+
+      g_slice_free (GimpTempBuf, (GimpTempBuf *) buf);
+    }
+}
+
+GimpTempBuf *
+gimp_temp_buf_scale (const GimpTempBuf *src,
+                     gint               new_width,
+                     gint               new_height)
+{
+  GimpTempBuf  *dest;
+  const guchar *src_data;
+  guchar       *dest_data;
+  gdouble       x_ratio;
+  gdouble       y_ratio;
+  gint          bytes;
+  gint          loop1;
+  gint          loop2;
+
+  g_return_val_if_fail (src != NULL, NULL);
+  g_return_val_if_fail (new_width > 0 && new_height > 0, NULL);
+
+  if (new_width == src->width && new_height == src->height)
+    return gimp_temp_buf_copy (src);
+
+  dest = gimp_temp_buf_new (new_width,
+                            new_height,
+                            src->format);
+
+  src_data  = gimp_temp_buf_get_data (src);
+  dest_data = gimp_temp_buf_get_data (dest);
+
+  x_ratio = (gdouble) src->width  / (gdouble) new_width;
+  y_ratio = (gdouble) src->height / (gdouble) new_height;
+
+  bytes = babl_format_get_bytes_per_pixel (src->format);
+
+  for (loop1 = 0 ; loop1 < new_height ; loop1++)
+    {
+      for (loop2 = 0 ; loop2 < new_width ; loop2++)
+        {
+          const guchar *src_pixel;
+          guchar       *dest_pixel;
+          gint          i;
+
+          src_pixel = src_data +
+            (gint) (loop2 * x_ratio) * bytes +
+            (gint) (loop1 * y_ratio) * bytes * src->width;
+
+          dest_pixel = dest_data +
+            (loop2 + loop1 * new_width) * bytes;
+
+          for (i = 0 ; i < bytes; i++)
+            *dest_pixel++ = *src_pixel++;
+        }
+    }
+
+  return dest;
+}
+
+gint
+gimp_temp_buf_get_width (const GimpTempBuf *buf)
+{
+  return buf->width;
+}
+
+gint
+gimp_temp_buf_get_height (const GimpTempBuf *buf)
+{
+  return buf->height;
+}
+
+const Babl *
+gimp_temp_buf_get_format (const GimpTempBuf *buf)
+{
+  return buf->format;
+}
+
+void
+gimp_temp_buf_set_format (GimpTempBuf *buf,
+                          const Babl  *format)
+{
+  g_return_if_fail (babl_format_get_bytes_per_pixel (buf->format) ==
+                    babl_format_get_bytes_per_pixel (format));
+
+  buf->format = format;
+}
+
+guchar *
+gimp_temp_buf_get_data (const GimpTempBuf *buf)
+{
+  return buf->data;
+}
+
+gsize
+gimp_temp_buf_get_data_size (const GimpTempBuf *buf)
+{
+  return (gsize) babl_format_get_bytes_per_pixel (buf->format) *
+                 buf->width * buf->height;
+}
+
+guchar *
+gimp_temp_buf_data_clear (GimpTempBuf *buf)
+{
+  memset (buf->data, 0, gimp_temp_buf_get_data_size (buf));
+
+  return buf->data;
+}
+
+gpointer
+gimp_temp_buf_lock (const GimpTempBuf *buf,
+                    const Babl        *format,
+                    GeglAccessMode     access_mode)
+{
+  guchar   *data;
+  LockData *lock_data;
+  gint      n_pixels;
+  gint      bpp;
+
+  g_return_val_if_fail (buf != NULL, NULL);
+
+  if (! format || format == buf->format)
+    return gimp_temp_buf_get_data (buf);
+
+  n_pixels = buf->width * buf->height;
+  bpp      = babl_format_get_bytes_per_pixel (format);
+
+  data = gegl_scratch_alloc (LOCK_DATA_ALIGNMENT + n_pixels * bpp);
+
+  if ((guintptr) data % LOCK_DATA_ALIGNMENT)
+    {
+      g_free (data);
+
+      g_return_val_if_reached (NULL);
+    }
+
+  lock_data              = (LockData *) data;
+  lock_data->format      = format;
+  lock_data->access_mode = access_mode;
+
+  data += LOCK_DATA_ALIGNMENT;
+
+  if (access_mode & GEGL_ACCESS_READ)
+    {
+      babl_process (babl_fish (buf->format, format),
+                    gimp_temp_buf_get_data (buf),
+                    data,
+                    n_pixels);
+    }
+
+  return data;
+}
+
+void
+gimp_temp_buf_unlock (const GimpTempBuf *buf,
+                      gconstpointer      data)
+{
+  LockData *lock_data;
+
+  g_return_if_fail (buf != NULL);
+  g_return_if_fail (data != NULL);
+
+  if (data == buf->data)
+    return;
+
+  lock_data = (LockData *) ((const guint8 *) data - LOCK_DATA_ALIGNMENT);
+
+  if (lock_data->access_mode & GEGL_ACCESS_WRITE)
+    {
+      babl_process (babl_fish (lock_data->format, buf->format),
+                    data,
+                    gimp_temp_buf_get_data (buf),
+                    buf->width * buf->height);
+    }
+
+  gegl_scratch_free (lock_data);
+}
+
+gsize
+gimp_temp_buf_get_memsize (const GimpTempBuf *buf)
+{
+  if (buf)
+    return (sizeof (GimpTempBuf) + gimp_temp_buf_get_data_size (buf));
+
+  return 0;
+}
+
+GeglBuffer *
+gimp_temp_buf_create_buffer (const GimpTempBuf *temp_buf)
+{
+  GeglBuffer *buffer;
+
+  g_return_val_if_fail (temp_buf != NULL, NULL);
+
+  buffer =
+    gegl_buffer_linear_new_from_data (gimp_temp_buf_get_data (temp_buf),
+                                      temp_buf->format,
+                                      GEGL_RECTANGLE (0, 0,
+                                                      temp_buf->width,
+                                                      temp_buf->height),
+                                      GEGL_AUTO_ROWSTRIDE,
+                                      (GDestroyNotify) gimp_temp_buf_unref,
+                                      gimp_temp_buf_ref (temp_buf));
+
+  g_object_set_data (G_OBJECT (buffer),
+                     "gimp-temp-buf", (GimpTempBuf *) temp_buf);
+
+  return buffer;
+}
+
+GdkPixbuf *
+gimp_temp_buf_create_pixbuf (const GimpTempBuf *temp_buf)
+{
+  GdkPixbuf    *pixbuf;
+  const Babl   *format;
+  const Babl   *fish = NULL;
+  const guchar *data;
+  gint          width;
+  gint          height;
+  gint          bpp;
+  guchar       *pixels;
+  gint          rowstride;
+  gint          i;
+
+  g_return_val_if_fail (temp_buf != NULL, NULL);
+
+  data      = gimp_temp_buf_get_data (temp_buf);
+  format    = gimp_temp_buf_get_format (temp_buf);
+  width     = gimp_temp_buf_get_width (temp_buf);
+  height    = gimp_temp_buf_get_height (temp_buf);
+  bpp       = babl_format_get_bytes_per_pixel (format);
+
+  pixbuf    = gdk_pixbuf_new (GDK_COLORSPACE_RGB,
+                              babl_format_has_alpha (format),
+                              8, width, height);
+
+  pixels    = gdk_pixbuf_get_pixels (pixbuf);
+  rowstride = gdk_pixbuf_get_rowstride (pixbuf);
+
+  if (format != gimp_pixbuf_get_format (pixbuf))
+    fish = babl_fish (format, gimp_pixbuf_get_format (pixbuf));
+
+  for (i = 0; i < height; i++)
+    {
+      if (fish)
+        babl_process (fish, data, pixels, width);
+      else
+        memcpy (pixels, data, width * bpp);
+
+      data   += width * bpp;
+      pixels += rowstride;
+    }
+
+  return pixbuf;
+}
+
+GimpTempBuf *
+gimp_gegl_buffer_get_temp_buf (GeglBuffer *buffer)
+{
+  g_return_val_if_fail (GEGL_IS_BUFFER (buffer), NULL);
+
+  return g_object_get_data (G_OBJECT (buffer), "gimp-temp-buf");
+}
+
+
+/*  public functions (stats)  */
+
+guint64
+gimp_temp_buf_get_total_memsize (void)
+{
+  return gimp_temp_buf_total_memsize;
+}
diff --git a/app/core/gimptempbuf.h b/app/core/gimptempbuf.h
new file mode 100644
index 0000000..d5228f5
--- /dev/null
+++ b/app/core/gimptempbuf.h
@@ -0,0 +1,67 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_TEMP_BUF_H__
+#define __GIMP_TEMP_BUF_H__
+
+
+GimpTempBuf * gimp_temp_buf_new               (gint               width,
+                                               gint               height,
+                                               const Babl        *format) G_GNUC_WARN_UNUSED_RESULT;
+GimpTempBuf * gimp_temp_buf_new_from_pixbuf   (GdkPixbuf         *pixbuf,
+                                               const Babl        *f_or_null) G_GNUC_WARN_UNUSED_RESULT;
+GimpTempBuf * gimp_temp_buf_copy              (const GimpTempBuf *src) G_GNUC_WARN_UNUSED_RESULT;
+
+GimpTempBuf * gimp_temp_buf_ref               (const GimpTempBuf *buf);
+void          gimp_temp_buf_unref             (const GimpTempBuf *buf);
+
+GimpTempBuf * gimp_temp_buf_scale             (const GimpTempBuf *buf,
+                                               gint               width,
+                                               gint               height) G_GNUC_WARN_UNUSED_RESULT;
+
+gint          gimp_temp_buf_get_width         (const GimpTempBuf *buf);
+gint          gimp_temp_buf_get_height        (const GimpTempBuf *buf);
+
+const Babl  * gimp_temp_buf_get_format        (const GimpTempBuf *buf);
+void          gimp_temp_buf_set_format        (GimpTempBuf       *buf,
+                                               const Babl        *format);
+
+guchar      * gimp_temp_buf_get_data          (const GimpTempBuf *buf);
+gsize         gimp_temp_buf_get_data_size     (const GimpTempBuf *buf);
+
+guchar      * gimp_temp_buf_data_clear        (GimpTempBuf       *buf);
+
+gpointer      gimp_temp_buf_lock              (const GimpTempBuf *buf,
+                                               const Babl        *format,
+                                               GeglAccessMode     access_mode) G_GNUC_WARN_UNUSED_RESULT;
+void          gimp_temp_buf_unlock            (const GimpTempBuf *buf,
+                                               gconstpointer      data);
+
+gsize         gimp_temp_buf_get_memsize       (const GimpTempBuf *buf);
+
+GeglBuffer  * gimp_temp_buf_create_buffer     (const GimpTempBuf *temp_buf) G_GNUC_WARN_UNUSED_RESULT;
+GdkPixbuf   * gimp_temp_buf_create_pixbuf     (const GimpTempBuf *temp_buf) G_GNUC_WARN_UNUSED_RESULT;
+
+GimpTempBuf * gimp_gegl_buffer_get_temp_buf   (GeglBuffer        *buffer);
+
+
+/*  stats  */
+
+guint64       gimp_temp_buf_get_total_memsize (void);
+
+
+#endif  /*  __GIMP_TEMP_BUF_H__  */
diff --git a/app/core/gimptemplate.c b/app/core/gimptemplate.c
new file mode 100644
index 0000000..1459493
--- /dev/null
+++ b/app/core/gimptemplate.c
@@ -0,0 +1,595 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1997 Spencer Kimball and Peter Mattis
+ *
+ * gimptemplate.c
+ * Copyright (C) 2003 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/* This file contains the definition of the image template objects.
+ */
+
+#include "config.h"
+
+#include <cairo.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpcolor/gimpcolor.h"
+#include "libgimpconfig/gimpconfig.h"
+
+#include "core-types.h"
+
+#include "gegl/gimp-babl.h"
+
+#include "gimpimage.h"
+#include "gimpprojection.h"
+#include "gimptemplate.h"
+
+#include "gimp-intl.h"
+
+
+#define DEFAULT_RESOLUTION 300.0
+
+enum
+{
+  PROP_0,
+  PROP_WIDTH,
+  PROP_HEIGHT,
+  PROP_UNIT,
+  PROP_XRESOLUTION,
+  PROP_YRESOLUTION,
+  PROP_RESOLUTION_UNIT,
+  PROP_BASE_TYPE,
+  PROP_PRECISION,
+  PROP_COMPONENT_TYPE,
+  PROP_LINEAR,
+  PROP_COLOR_MANAGED,
+  PROP_COLOR_PROFILE,
+  PROP_FILL_TYPE,
+  PROP_COMMENT,
+  PROP_FILENAME
+};
+
+
+typedef struct _GimpTemplatePrivate GimpTemplatePrivate;
+
+struct _GimpTemplatePrivate
+{
+  gint               width;
+  gint               height;
+  GimpUnit           unit;
+
+  gdouble            xresolution;
+  gdouble            yresolution;
+  GimpUnit           resolution_unit;
+
+  GimpImageBaseType  base_type;
+  GimpPrecision      precision;
+
+  gboolean           color_managed;
+  GFile             *color_profile;
+
+  GimpFillType       fill_type;
+
+  gchar             *comment;
+  gchar             *filename;
+
+  guint64            initial_size;
+};
+
+#define GET_PRIVATE(template) ((GimpTemplatePrivate *) gimp_template_get_instance_private ((GimpTemplate *) (template)))
+
+
+static void      gimp_template_finalize     (GObject      *object);
+static void      gimp_template_set_property (GObject      *object,
+                                             guint         property_id,
+                                             const GValue *value,
+                                             GParamSpec   *pspec);
+static void      gimp_template_get_property (GObject      *object,
+                                             guint         property_id,
+                                             GValue       *value,
+                                             GParamSpec   *pspec);
+static void      gimp_template_notify       (GObject      *object,
+                                             GParamSpec   *pspec);
+
+
+G_DEFINE_TYPE_WITH_CODE (GimpTemplate, gimp_template, GIMP_TYPE_VIEWABLE,
+                         G_ADD_PRIVATE (GimpTemplate)
+                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_CONFIG, NULL))
+
+#define parent_class gimp_template_parent_class
+
+
+static void
+gimp_template_class_init (GimpTemplateClass *klass)
+{
+  GObjectClass      *object_class   = G_OBJECT_CLASS (klass);
+  GimpViewableClass *viewable_class = GIMP_VIEWABLE_CLASS (klass);
+
+  object_class->finalize     = gimp_template_finalize;
+
+  object_class->set_property = gimp_template_set_property;
+  object_class->get_property = gimp_template_get_property;
+  object_class->notify       = gimp_template_notify;
+
+  viewable_class->default_icon_name = "gimp-template";
+  viewable_class->name_editable     = TRUE;
+
+  GIMP_CONFIG_PROP_INT (object_class, PROP_WIDTH,
+                        "width",
+                        _("Width"),
+                        NULL,
+                        GIMP_MIN_IMAGE_SIZE, GIMP_MAX_IMAGE_SIZE,
+                        GIMP_DEFAULT_IMAGE_WIDTH,
+                        GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_INT (object_class, PROP_HEIGHT,
+                        "height",
+                        _("Height"),
+                        NULL,
+                        GIMP_MIN_IMAGE_SIZE, GIMP_MAX_IMAGE_SIZE,
+                        GIMP_DEFAULT_IMAGE_HEIGHT,
+                        GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_UNIT (object_class, PROP_UNIT,
+                         "unit",
+                         _("Unit"),
+                         _("The unit used for coordinate display "
+                           "when not in dot-for-dot mode."),
+                         TRUE, FALSE, GIMP_UNIT_PIXEL,
+                         GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_RESOLUTION (object_class, PROP_XRESOLUTION,
+                               "xresolution",
+                               _("Resolution X"),
+                               _("The horizontal image resolution."),
+                               DEFAULT_RESOLUTION,
+                               GIMP_PARAM_STATIC_STRINGS |
+                               GIMP_TEMPLATE_PARAM_COPY_FIRST);
+
+  GIMP_CONFIG_PROP_RESOLUTION (object_class, PROP_YRESOLUTION,
+                               "yresolution",
+                               _("Resolution X"),
+                               _("The vertical image resolution."),
+                               DEFAULT_RESOLUTION,
+                               GIMP_PARAM_STATIC_STRINGS |
+                               GIMP_TEMPLATE_PARAM_COPY_FIRST);
+
+  GIMP_CONFIG_PROP_UNIT (object_class, PROP_RESOLUTION_UNIT,
+                         "resolution-unit",
+                         _("Resolution unit"),
+                         NULL,
+                         FALSE, FALSE, GIMP_UNIT_INCH,
+                         GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_ENUM (object_class, PROP_BASE_TYPE,
+                         "image-type", /* serialized name */
+                         _("Image type"),
+                         NULL,
+                         GIMP_TYPE_IMAGE_BASE_TYPE, GIMP_RGB,
+                         GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_ENUM (object_class, PROP_PRECISION,
+                         "precision",
+                         _("Precision"),
+                         NULL,
+                         GIMP_TYPE_PRECISION, GIMP_PRECISION_U8_GAMMA,
+                         GIMP_PARAM_STATIC_STRINGS);
+
+  g_object_class_install_property (object_class, PROP_COMPONENT_TYPE,
+                                   g_param_spec_enum ("component-type",
+                                                      _("Precision"),
+                                                      NULL,
+                                                      GIMP_TYPE_COMPONENT_TYPE,
+                                                      GIMP_COMPONENT_TYPE_U8,
+                                                      G_PARAM_READWRITE |
+                                                      GIMP_PARAM_STATIC_STRINGS));
+
+  g_object_class_install_property (object_class, PROP_LINEAR,
+                                   g_param_spec_boolean ("linear",
+                                                         _("Gamma"),
+                                                         NULL,
+                                                         FALSE,
+                                                         G_PARAM_READWRITE |
+                                                         GIMP_PARAM_STATIC_STRINGS));
+
+  GIMP_CONFIG_PROP_BOOLEAN (object_class, PROP_COLOR_MANAGED,
+                            "color-managed",
+                            _("Color managed"),
+                            _("Whether the image is color managed. "
+                              "Disabling color management is equivalent to "
+                              "choosing a built-in sRGB profile. Better "
+                              "leave color management enabled."),
+                            TRUE,
+                            GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_OBJECT (object_class, PROP_COLOR_PROFILE,
+                           "color-profile",
+                           _("Color profile"),
+                           NULL,
+                           G_TYPE_FILE,
+                           GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_ENUM (object_class, PROP_FILL_TYPE,
+                         "fill-type",
+                         _("Fill type"),
+                         NULL,
+                         GIMP_TYPE_FILL_TYPE, GIMP_FILL_BACKGROUND,
+                         GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_STRING (object_class, PROP_COMMENT,
+                           "comment",
+                           _("Comment"),
+                           NULL,
+                           NULL,
+                           GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_STRING (object_class, PROP_FILENAME,
+                           "filename",
+                           _("Filename"),
+                           NULL,
+                           NULL,
+                           GIMP_PARAM_STATIC_STRINGS);
+}
+
+static void
+gimp_template_init (GimpTemplate *template)
+{
+}
+
+static void
+gimp_template_finalize (GObject *object)
+{
+  GimpTemplatePrivate *private = GET_PRIVATE (object);
+
+  g_clear_object (&private->color_profile);
+  g_clear_pointer (&private->comment,  g_free);
+  g_clear_pointer (&private->filename, g_free);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gimp_template_set_property (GObject      *object,
+                            guint         property_id,
+                            const GValue *value,
+                            GParamSpec   *pspec)
+{
+  GimpTemplatePrivate *private = GET_PRIVATE (object);
+
+  switch (property_id)
+    {
+    case PROP_WIDTH:
+      private->width = g_value_get_int (value);
+      break;
+    case PROP_HEIGHT:
+      private->height = g_value_get_int (value);
+      break;
+    case PROP_UNIT:
+      private->unit = g_value_get_int (value);
+      break;
+    case PROP_XRESOLUTION:
+      private->xresolution = g_value_get_double (value);
+      break;
+    case PROP_YRESOLUTION:
+      private->yresolution = g_value_get_double (value);
+      break;
+    case PROP_RESOLUTION_UNIT:
+      private->resolution_unit = g_value_get_int (value);
+      break;
+    case PROP_BASE_TYPE:
+      private->base_type = g_value_get_enum (value);
+      break;
+    case PROP_PRECISION:
+      private->precision = g_value_get_enum (value);
+      g_object_notify (object, "component-type");
+      g_object_notify (object, "linear");
+      break;
+    case PROP_COMPONENT_TYPE:
+      private->precision =
+        gimp_babl_precision (g_value_get_enum (value),
+                             gimp_babl_linear (private->precision));
+      g_object_notify (object, "precision");
+      break;
+    case PROP_LINEAR:
+      private->precision =
+        gimp_babl_precision (gimp_babl_component_type (private->precision),
+                             g_value_get_boolean (value));
+      g_object_notify (object, "precision");
+      break;
+    case PROP_COLOR_MANAGED:
+      private->color_managed = g_value_get_boolean (value);
+      break;
+    case PROP_COLOR_PROFILE:
+      if (private->color_profile)
+        g_object_unref (private->color_profile);
+      private->color_profile = g_value_dup_object (value);
+      break;
+    case PROP_FILL_TYPE:
+      private->fill_type = g_value_get_enum (value);
+      break;
+    case PROP_COMMENT:
+      if (private->comment)
+        g_free (private->comment);
+      private->comment = g_value_dup_string (value);
+      break;
+    case PROP_FILENAME:
+      if (private->filename)
+        g_free (private->filename);
+      private->filename = g_value_dup_string (value);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_template_get_property (GObject    *object,
+                            guint       property_id,
+                            GValue     *value,
+                            GParamSpec *pspec)
+{
+  GimpTemplatePrivate *private = GET_PRIVATE (object);
+
+  switch (property_id)
+    {
+    case PROP_WIDTH:
+      g_value_set_int (value, private->width);
+      break;
+    case PROP_HEIGHT:
+      g_value_set_int (value, private->height);
+      break;
+    case PROP_UNIT:
+      g_value_set_int (value, private->unit);
+      break;
+    case PROP_XRESOLUTION:
+      g_value_set_double (value, private->xresolution);
+      break;
+    case PROP_YRESOLUTION:
+      g_value_set_double (value, private->yresolution);
+      break;
+    case PROP_RESOLUTION_UNIT:
+      g_value_set_int (value, private->resolution_unit);
+      break;
+    case PROP_BASE_TYPE:
+      g_value_set_enum (value, private->base_type);
+      break;
+    case PROP_PRECISION:
+      g_value_set_enum (value, private->precision);
+      break;
+    case PROP_COMPONENT_TYPE:
+      g_value_set_enum (value, gimp_babl_component_type (private->precision));
+      break;
+    case PROP_LINEAR:
+      g_value_set_boolean (value, gimp_babl_linear (private->precision));
+      break;
+    case PROP_COLOR_MANAGED:
+      g_value_set_boolean (value, private->color_managed);
+      break;
+    case PROP_COLOR_PROFILE:
+      g_value_set_object (value, private->color_profile);
+      break;
+    case PROP_FILL_TYPE:
+      g_value_set_enum (value, private->fill_type);
+      break;
+    case PROP_COMMENT:
+      g_value_set_string (value, private->comment);
+      break;
+    case PROP_FILENAME:
+      g_value_set_string (value, private->filename);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_template_notify (GObject    *object,
+                      GParamSpec *pspec)
+{
+  GimpTemplatePrivate *private = GET_PRIVATE (object);
+  const Babl          *format;
+  gint                 bytes;
+
+  if (G_OBJECT_CLASS (parent_class)->notify)
+    G_OBJECT_CLASS (parent_class)->notify (object, pspec);
+
+  /* the initial layer */
+  format = gimp_babl_format (private->base_type,
+                             private->precision,
+                             private->fill_type == GIMP_FILL_TRANSPARENT);
+  bytes = babl_format_get_bytes_per_pixel (format);
+
+  /* the selection */
+  format = gimp_babl_mask_format (private->precision);
+  bytes += babl_format_get_bytes_per_pixel (format);
+
+  private->initial_size = ((guint64) bytes          *
+                           (guint64) private->width *
+                           (guint64) private->height);
+
+  private->initial_size +=
+    gimp_projection_estimate_memsize (private->base_type,
+                                      gimp_babl_component_type (private->precision),
+                                      private->width, private->height);
+}
+
+
+/*  public functions  */
+
+GimpTemplate *
+gimp_template_new (const gchar *name)
+{
+  g_return_val_if_fail (name != NULL, NULL);
+
+  return g_object_new (GIMP_TYPE_TEMPLATE,
+                       "name", name,
+                       NULL);
+}
+
+void
+gimp_template_set_from_image (GimpTemplate *template,
+                              GimpImage    *image)
+{
+  gdouble             xresolution;
+  gdouble             yresolution;
+  GimpImageBaseType   base_type;
+  const GimpParasite *parasite;
+  gchar              *comment = NULL;
+
+  g_return_if_fail (GIMP_IS_TEMPLATE (template));
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  gimp_image_get_resolution (image, &xresolution, &yresolution);
+
+  base_type = gimp_image_get_base_type (image);
+
+  if (base_type == GIMP_INDEXED)
+    base_type = GIMP_RGB;
+
+  parasite =  gimp_image_parasite_find (image, "gimp-comment");
+  if (parasite)
+    comment = g_strndup (gimp_parasite_data (parasite),
+                         gimp_parasite_data_size (parasite));
+
+  g_object_set (template,
+                "width",           gimp_image_get_width (image),
+                "height",          gimp_image_get_height (image),
+                "xresolution",     xresolution,
+                "yresolution",     yresolution,
+                "resolution-unit", gimp_image_get_unit (image),
+                "image-type",      base_type,
+                "precision",       gimp_image_get_precision (image),
+                "comment",         comment,
+                NULL);
+
+  if (comment)
+    g_free (comment);
+}
+
+gint
+gimp_template_get_width (GimpTemplate *template)
+{
+  g_return_val_if_fail (GIMP_IS_TEMPLATE (template), 0);
+
+  return GET_PRIVATE (template)->width;
+}
+
+gint
+gimp_template_get_height (GimpTemplate *template)
+{
+  g_return_val_if_fail (GIMP_IS_TEMPLATE (template), 0);
+
+  return GET_PRIVATE (template)->height;
+}
+
+GimpUnit
+gimp_template_get_unit (GimpTemplate *template)
+{
+  g_return_val_if_fail (GIMP_IS_TEMPLATE (template), GIMP_UNIT_INCH);
+
+  return GET_PRIVATE (template)->unit;
+}
+
+gdouble
+gimp_template_get_resolution_x (GimpTemplate *template)
+{
+  g_return_val_if_fail (GIMP_IS_TEMPLATE (template), 1.0);
+
+  return GET_PRIVATE (template)->xresolution;
+}
+
+gdouble
+gimp_template_get_resolution_y (GimpTemplate *template)
+{
+  g_return_val_if_fail (GIMP_IS_TEMPLATE (template), 1.0);
+
+  return GET_PRIVATE (template)->yresolution;
+}
+
+GimpUnit
+gimp_template_get_resolution_unit (GimpTemplate *template)
+{
+  g_return_val_if_fail (GIMP_IS_TEMPLATE (template), GIMP_UNIT_INCH);
+
+  return GET_PRIVATE (template)->resolution_unit;
+}
+
+GimpImageBaseType
+gimp_template_get_base_type (GimpTemplate *template)
+{
+  g_return_val_if_fail (GIMP_IS_TEMPLATE (template), GIMP_RGB);
+
+  return GET_PRIVATE (template)->base_type;
+}
+
+GimpPrecision
+gimp_template_get_precision (GimpTemplate *template)
+{
+  g_return_val_if_fail (GIMP_IS_TEMPLATE (template), GIMP_PRECISION_U8_GAMMA);
+
+  return GET_PRIVATE (template)->precision;
+}
+
+gboolean
+gimp_template_get_color_managed (GimpTemplate *template)
+{
+  g_return_val_if_fail (GIMP_IS_TEMPLATE (template), FALSE);
+
+  return GET_PRIVATE (template)->color_managed;
+}
+
+GimpColorProfile *
+gimp_template_get_color_profile (GimpTemplate *template)
+{
+  GimpTemplatePrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_TEMPLATE (template), FALSE);
+
+  private = GET_PRIVATE (template);
+
+  if (private->color_profile)
+    return gimp_color_profile_new_from_file (private->color_profile, NULL);
+
+  return NULL;
+}
+
+GimpFillType
+gimp_template_get_fill_type (GimpTemplate *template)
+{
+  g_return_val_if_fail (GIMP_IS_TEMPLATE (template), GIMP_FILL_BACKGROUND);
+
+  return GET_PRIVATE (template)->fill_type;
+}
+
+const gchar *
+gimp_template_get_comment (GimpTemplate *template)
+{
+  g_return_val_if_fail (GIMP_IS_TEMPLATE (template), NULL);
+
+  return GET_PRIVATE (template)->comment;
+}
+
+guint64
+gimp_template_get_initial_size (GimpTemplate *template)
+{
+  g_return_val_if_fail (GIMP_IS_TEMPLATE (template), 0);
+
+  return GET_PRIVATE (template)->initial_size;
+}
diff --git a/app/core/gimptemplate.h b/app/core/gimptemplate.h
new file mode 100644
index 0000000..671a247
--- /dev/null
+++ b/app/core/gimptemplate.h
@@ -0,0 +1,97 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1999 Spencer Kimball and Peter Mattis
+ *
+ * gimptemplate.h
+ * Copyright (C) 2003 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_TEMPLATE_H__
+#define __GIMP_TEMPLATE_H__
+
+
+#include "gimpviewable.h"
+
+
+#define GIMP_TEMPLATE_PARAM_COPY_FIRST (1 << (8 + G_PARAM_USER_SHIFT))
+
+#ifdef GIMP_UNSTABLE
+/* Uncommon ratio, with at least one odd value, to encourage testing
+ * GIMP with unusual numbers.
+ * It also has to be a higher resolution, to push GIMP a little further
+ * in tests. */
+#define GIMP_DEFAULT_IMAGE_WIDTH   2001
+#define GIMP_DEFAULT_IMAGE_HEIGHT  1984
+#else
+/* 1366x768 is the most common screen resolution in 2016.
+ * 1920x1080 is the second most common.
+ * Since GIMP targets advanced graphics artists, let's go for the
+ * highest common dimension.
+ */
+#define GIMP_DEFAULT_IMAGE_WIDTH   1920
+#define GIMP_DEFAULT_IMAGE_HEIGHT  1080
+#endif
+
+
+#define GIMP_TYPE_TEMPLATE            (gimp_template_get_type ())
+#define GIMP_TEMPLATE(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_TEMPLATE, GimpTemplate))
+#define GIMP_TEMPLATE_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_TEMPLATE, GimpTemplateClass))
+#define GIMP_IS_TEMPLATE(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_TEMPLATE))
+#define GIMP_IS_TEMPLATE_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_TEMPLATE))
+#define GIMP_TEMPLATE_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_TEMPLATE, GimpTemplateClass))
+
+
+typedef struct _GimpTemplateClass GimpTemplateClass;
+
+struct _GimpTemplate
+{
+  GimpViewable  parent_instance;
+};
+
+struct _GimpTemplateClass
+{
+  GimpViewableClass  parent_instance;
+};
+
+
+GType               gimp_template_get_type            (void) G_GNUC_CONST;
+
+GimpTemplate      * gimp_template_new                 (const gchar  *name);
+
+void                gimp_template_set_from_image      (GimpTemplate *template,
+                                                       GimpImage    *image);
+
+gint                gimp_template_get_width           (GimpTemplate *template);
+gint                gimp_template_get_height          (GimpTemplate *template);
+GimpUnit            gimp_template_get_unit            (GimpTemplate *template);
+
+gdouble             gimp_template_get_resolution_x    (GimpTemplate *template);
+gdouble             gimp_template_get_resolution_y    (GimpTemplate *template);
+GimpUnit            gimp_template_get_resolution_unit (GimpTemplate *template);
+
+GimpImageBaseType   gimp_template_get_base_type       (GimpTemplate *template);
+GimpPrecision       gimp_template_get_precision       (GimpTemplate *template);
+
+gboolean            gimp_template_get_color_managed   (GimpTemplate *template);
+GimpColorProfile  * gimp_template_get_color_profile   (GimpTemplate *template);
+
+GimpFillType        gimp_template_get_fill_type       (GimpTemplate *template);
+
+const gchar       * gimp_template_get_comment         (GimpTemplate *template);
+
+guint64             gimp_template_get_initial_size    (GimpTemplate *template);
+
+
+#endif /* __GIMP_TEMPLATE__ */
diff --git a/app/core/gimptilehandlerprojectable.c b/app/core/gimptilehandlerprojectable.c
new file mode 100644
index 0000000..4b9e86b
--- /dev/null
+++ b/app/core/gimptilehandlerprojectable.c
@@ -0,0 +1,91 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gegl.h>
+#include <cairo.h>
+
+#include "core-types.h"
+
+#include "gimpprojectable.h"
+
+#include "gimptilehandlerprojectable.h"
+
+
+static void   gimp_tile_handler_projectable_begin_validate (GimpTileHandlerValidate *validate);
+static void   gimp_tile_handler_projectable_end_validate   (GimpTileHandlerValidate *validate);
+
+
+G_DEFINE_TYPE (GimpTileHandlerProjectable, gimp_tile_handler_projectable,
+               GIMP_TYPE_TILE_HANDLER_VALIDATE)
+
+#define parent_class gimp_tile_handler_projectable_parent_class
+
+
+static void
+gimp_tile_handler_projectable_class_init (GimpTileHandlerProjectableClass *klass)
+{
+  GimpTileHandlerValidateClass *validate_class;
+
+  validate_class = GIMP_TILE_HANDLER_VALIDATE_CLASS (klass);
+
+  validate_class->begin_validate = gimp_tile_handler_projectable_begin_validate;
+  validate_class->end_validate   = gimp_tile_handler_projectable_end_validate;
+}
+
+static void
+gimp_tile_handler_projectable_init (GimpTileHandlerProjectable *projectable)
+{
+}
+
+static void
+gimp_tile_handler_projectable_begin_validate (GimpTileHandlerValidate *validate)
+{
+  GimpTileHandlerProjectable *handler = GIMP_TILE_HANDLER_PROJECTABLE (validate);
+
+  GIMP_TILE_HANDLER_VALIDATE_CLASS (parent_class)->begin_validate (validate);
+
+  gimp_projectable_begin_render (handler->projectable);
+}
+
+static void
+gimp_tile_handler_projectable_end_validate (GimpTileHandlerValidate *validate)
+{
+  GimpTileHandlerProjectable *handler = GIMP_TILE_HANDLER_PROJECTABLE (validate);
+
+  gimp_projectable_end_render (handler->projectable);
+
+  GIMP_TILE_HANDLER_VALIDATE_CLASS (parent_class)->end_validate (validate);
+}
+
+GeglTileHandler *
+gimp_tile_handler_projectable_new (GimpProjectable *projectable)
+{
+  GimpTileHandlerProjectable *handler;
+
+  g_return_val_if_fail (GIMP_IS_PROJECTABLE (projectable), NULL);
+
+  handler = g_object_new (GIMP_TYPE_TILE_HANDLER_PROJECTABLE, NULL);
+
+  GIMP_TILE_HANDLER_VALIDATE (handler)->graph =
+    g_object_ref (gimp_projectable_get_graph (projectable));
+
+  handler->projectable = projectable;
+
+  return GEGL_TILE_HANDLER (handler);
+}
diff --git a/app/core/gimptilehandlerprojectable.h b/app/core/gimptilehandlerprojectable.h
new file mode 100644
index 0000000..57af4b6
--- /dev/null
+++ b/app/core/gimptilehandlerprojectable.h
@@ -0,0 +1,64 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_TILE_HANDLER_PROJECTABLE_H__
+#define __GIMP_TILE_HANDLER_PROJECTABLE_H__
+
+
+#include "gegl/gimptilehandlervalidate.h"
+
+
+/***
+ * GimpTileHandlerProjectable is a GeglTileHandler that renders a
+ * projectable, calling the projectable's begin_render() and end_render()
+ * before/after the actual rendering.
+ *
+ * Note that the tile handler does not own a reference to the projectable.
+ * It's the user's responsibility to manage the handler's and projectable's
+ * lifetime.
+ */
+
+#define GIMP_TYPE_TILE_HANDLER_PROJECTABLE            (gimp_tile_handler_projectable_get_type ())
+#define GIMP_TILE_HANDLER_PROJECTABLE(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_TILE_HANDLER_PROJECTABLE, GimpTileHandlerProjectable))
+#define GIMP_TILE_HANDLER_PROJECTABLE_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass),  GIMP_TYPE_TILE_HANDLER_PROJECTABLE, GimpTileHandlerProjectableClass))
+#define GIMP_IS_TILE_HANDLER_PROJECTABLE(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_TILE_HANDLER_PROJECTABLE))
+#define GIMP_IS_TILE_HANDLER_PROJECTABLE_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass),  GIMP_TYPE_TILE_HANDLER_PROJECTABLE))
+#define GIMP_TILE_HANDLER_PROJECTABLE_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj),  GIMP_TYPE_TILE_HANDLER_PROJECTABLE, GimpTileHandlerProjectableClass))
+
+
+typedef struct _GimpTileHandlerProjectable      GimpTileHandlerProjectable;
+typedef struct _GimpTileHandlerProjectableClass GimpTileHandlerProjectableClass;
+
+struct _GimpTileHandlerProjectable
+{
+  GimpTileHandlerValidate  parent_instance;
+
+  GimpProjectable         *projectable;
+};
+
+struct _GimpTileHandlerProjectableClass
+{
+  GimpTileHandlerValidateClass  parent_class;
+};
+
+
+GType             gimp_tile_handler_projectable_get_type (void) G_GNUC_CONST;
+
+GeglTileHandler * gimp_tile_handler_projectable_new      (GimpProjectable *projectable);
+
+
+#endif /* __GIMP_TILE_HANDLER_PROJECTABLE_H__ */
diff --git a/app/core/gimptoolgroup.c b/app/core/gimptoolgroup.c
new file mode 100644
index 0000000..aa8e3bc
--- /dev/null
+++ b/app/core/gimptoolgroup.c
@@ -0,0 +1,413 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimptoolgroup.c
+ * Copyright (C) 2020 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpconfig/gimpconfig.h"
+
+#include "core-types.h"
+
+#include "gimplist.h"
+#include "gimpmarshal.h"
+#include "gimptoolgroup.h"
+#include "gimptoolinfo.h"
+
+#include "gimp-intl.h"
+
+
+enum
+{
+  ACTIVE_TOOL_CHANGED,
+  LAST_SIGNAL
+};
+
+enum
+{
+  PROP_0,
+  PROP_ACTIVE_TOOL,
+  PROP_CHILDREN
+};
+
+
+struct _GimpToolGroupPrivate
+{
+  gchar         *active_tool;
+  GimpContainer *children;
+};
+
+
+/*  local function prototypes  */
+
+
+static void            gimp_tool_group_finalize        (GObject        *object);
+static void            gimp_tool_group_get_property    (GObject        *object,
+                                                        guint           property_id,
+                                                        GValue         *value,
+                                                        GParamSpec     *pspec);
+static void            gimp_tool_group_set_property    (GObject        *object,
+                                                        guint           property_id,
+                                                        const GValue   *value,
+                                                        GParamSpec     *pspec);
+
+static gint64          gimp_tool_group_get_memsize     (GimpObject     *object,
+                                                        gint64         *gui_size);
+
+static gchar         * gimp_tool_group_get_description (GimpViewable   *viewable,
+                                                        gchar         **tooltip);
+static GimpContainer * gimp_tool_group_get_children    (GimpViewable   *viewable);
+static void            gimp_tool_group_set_expanded    (GimpViewable   *viewable,
+                                                        gboolean        expand);
+static gboolean        gimp_tool_group_get_expanded    (GimpViewable   *viewable);
+
+static void            gimp_tool_group_child_add       (GimpContainer  *container,
+                                                        GimpToolInfo   *tool_info,
+                                                        GimpToolGroup  *tool_group);
+static void            gimp_tool_group_child_remove    (GimpContainer  *container,
+                                                        GimpToolInfo   *tool_info,
+                                                        GimpToolGroup  *tool_group);
+
+static void            gimp_tool_group_shown_changed   (GimpToolItem   *tool_item);
+
+
+G_DEFINE_TYPE_WITH_PRIVATE (GimpToolGroup, gimp_tool_group, GIMP_TYPE_TOOL_ITEM)
+
+#define parent_class gimp_tool_group_parent_class
+
+static guint gimp_tool_group_signals[LAST_SIGNAL] = { 0 };
+
+
+/*  private functions  */
+
+static void
+gimp_tool_group_class_init (GimpToolGroupClass *klass)
+{
+  GObjectClass      *object_class      = G_OBJECT_CLASS (klass);
+  GimpObjectClass   *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+  GimpViewableClass *viewable_class    = GIMP_VIEWABLE_CLASS (klass);
+  GimpToolItemClass *tool_item_class   = GIMP_TOOL_ITEM_CLASS (klass);
+
+  gimp_tool_group_signals[ACTIVE_TOOL_CHANGED] =
+    g_signal_new ("active-tool-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpToolGroupClass, active_tool_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  object_class->finalize            = gimp_tool_group_finalize;
+  object_class->get_property        = gimp_tool_group_get_property;
+  object_class->set_property        = gimp_tool_group_set_property;
+
+  gimp_object_class->get_memsize    = gimp_tool_group_get_memsize;
+
+  viewable_class->default_icon_name = "folder";
+  viewable_class->get_description   = gimp_tool_group_get_description;
+  viewable_class->get_children      = gimp_tool_group_get_children;
+  viewable_class->get_expanded      = gimp_tool_group_get_expanded;
+  viewable_class->set_expanded      = gimp_tool_group_set_expanded;
+
+  tool_item_class->shown_changed    = gimp_tool_group_shown_changed;
+
+  GIMP_CONFIG_PROP_STRING (object_class, PROP_ACTIVE_TOOL,
+                           "active-tool", NULL, NULL,
+                           NULL,
+                           GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_OBJECT (object_class, PROP_CHILDREN,
+                           "children", NULL, NULL,
+                           GIMP_TYPE_CONTAINER,
+                           GIMP_PARAM_STATIC_STRINGS |
+                           GIMP_CONFIG_PARAM_AGGREGATE);
+}
+
+static void
+gimp_tool_group_init (GimpToolGroup *tool_group)
+{
+  tool_group->priv = gimp_tool_group_get_instance_private (tool_group);
+
+  tool_group->priv->children = g_object_new (
+    GIMP_TYPE_LIST,
+    "children-type", GIMP_TYPE_TOOL_INFO,
+    "append",        TRUE,
+    NULL);
+
+  g_signal_connect (tool_group->priv->children, "add",
+                    G_CALLBACK (gimp_tool_group_child_add),
+                    tool_group);
+  g_signal_connect (tool_group->priv->children, "remove",
+                    G_CALLBACK (gimp_tool_group_child_remove),
+                    tool_group);
+}
+
+static void
+gimp_tool_group_finalize (GObject *object)
+{
+  GimpToolGroup *tool_group = GIMP_TOOL_GROUP (object);
+
+  g_clear_pointer (&tool_group->priv->active_tool, g_free);
+
+  g_clear_object (&tool_group->priv->children);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gimp_tool_group_get_property (GObject    *object,
+                              guint       property_id,
+                              GValue     *value,
+                              GParamSpec *pspec)
+{
+  GimpToolGroup *tool_group = GIMP_TOOL_GROUP (object);
+
+  switch (property_id)
+    {
+    case PROP_ACTIVE_TOOL:
+      g_value_set_string (value, tool_group->priv->active_tool);
+      break;
+
+    case PROP_CHILDREN:
+      g_value_set_object (value, tool_group->priv->children);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_tool_group_set_property_add_tool (GimpToolInfo  *tool_info,
+                                       GimpToolGroup *tool_group)
+{
+  gimp_container_add (tool_group->priv->children, GIMP_OBJECT (tool_info));
+}
+
+static void
+gimp_tool_group_set_property (GObject      *object,
+                              guint         property_id,
+                              const GValue *value,
+                              GParamSpec   *pspec)
+{
+  GimpToolGroup *tool_group = GIMP_TOOL_GROUP (object);
+
+  switch (property_id)
+    {
+    case PROP_ACTIVE_TOOL:
+      g_free (tool_group->priv->active_tool);
+
+      tool_group->priv->active_tool = g_value_dup_string (value);
+      break;
+
+    case PROP_CHILDREN:
+      {
+        GimpContainer *container = g_value_get_object (value);
+
+        gimp_container_clear (tool_group->priv->children);
+
+        if (! container)
+          break;
+
+        gimp_container_foreach (container,
+                                (GFunc) gimp_tool_group_set_property_add_tool,
+                                tool_group);
+      }
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static gint64
+gimp_tool_group_get_memsize (GimpObject *object,
+                             gint64     *gui_size)
+{
+  GimpToolGroup *tool_group = GIMP_TOOL_GROUP (object);
+  gint64         memsize = 0;
+
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (tool_group->priv->children),
+                                      gui_size);
+
+  return memsize + GIMP_OBJECT_CLASS (parent_class)->get_memsize (object,
+                                                                  gui_size);
+}
+
+static gchar *
+gimp_tool_group_get_description (GimpViewable  *viewable,
+                                 gchar        **tooltip)
+{
+  /* Translators: this is a noun */
+  return g_strdup (C_("tool-item", "Group"));
+}
+
+static GimpContainer *
+gimp_tool_group_get_children (GimpViewable *viewable)
+{
+  GimpToolGroup *tool_group = GIMP_TOOL_GROUP (viewable);
+
+  return tool_group->priv->children;
+}
+
+static void
+gimp_tool_group_set_expanded (GimpViewable *viewable,
+                              gboolean      expand)
+{
+  if (! expand)
+    gimp_viewable_expanded_changed (viewable);
+}
+
+static gboolean
+gimp_tool_group_get_expanded (GimpViewable *viewable)
+{
+  return TRUE;
+}
+
+static void
+gimp_tool_group_child_add (GimpContainer *container,
+                           GimpToolInfo  *tool_info,
+                           GimpToolGroup *tool_group)
+{
+  g_return_if_fail (
+    gimp_viewable_get_parent (GIMP_VIEWABLE (tool_info)) == NULL);
+
+  gimp_viewable_set_parent (GIMP_VIEWABLE (tool_info),
+                            GIMP_VIEWABLE (tool_group));
+
+  if (! tool_group->priv->active_tool)
+    gimp_tool_group_set_active_tool_info (tool_group, tool_info);
+}
+
+static void
+gimp_tool_group_child_remove (GimpContainer *container,
+                              GimpToolInfo  *tool_info,
+                              GimpToolGroup *tool_group)
+{
+  gimp_viewable_set_parent (GIMP_VIEWABLE (tool_info), NULL);
+
+  if (! g_strcmp0 (tool_group->priv->active_tool,
+                   gimp_object_get_name (GIMP_OBJECT (tool_info))))
+    {
+      GimpToolInfo *active_tool_info = NULL;
+
+      if (! gimp_container_is_empty (tool_group->priv->children))
+        {
+          active_tool_info = GIMP_TOOL_INFO (
+            gimp_container_get_first_child (tool_group->priv->children));
+        }
+
+      gimp_tool_group_set_active_tool_info (tool_group, active_tool_info);
+    }
+}
+
+static void
+gimp_tool_group_shown_changed (GimpToolItem *tool_item)
+{
+  GimpToolGroup *tool_group = GIMP_TOOL_GROUP (tool_item);
+  GList         *iter;
+
+  if (GIMP_TOOL_ITEM_CLASS (parent_class)->shown_changed)
+    GIMP_TOOL_ITEM_CLASS (parent_class)->shown_changed (tool_item);
+
+  for (iter = GIMP_LIST (tool_group->priv->children)->queue->head;
+       iter;
+       iter = g_list_next (iter))
+    {
+      GimpToolItem *tool_item = iter->data;
+
+      if (gimp_tool_item_get_visible (tool_item))
+        gimp_tool_item_shown_changed (tool_item);
+    }
+}
+
+
+/*  public functions  */
+
+GimpToolGroup *
+gimp_tool_group_new (void)
+{
+  GimpToolGroup *tool_group;
+
+  tool_group = g_object_new (GIMP_TYPE_TOOL_GROUP, NULL);
+
+  gimp_object_set_static_name (GIMP_OBJECT (tool_group), "tool group");
+
+  return tool_group;
+}
+
+void
+gimp_tool_group_set_active_tool (GimpToolGroup *tool_group,
+                                 const gchar   *tool_name)
+{
+  g_return_if_fail (GIMP_IS_TOOL_GROUP (tool_group));
+
+  if (g_strcmp0 (tool_group->priv->active_tool, tool_name))
+    {
+      g_return_if_fail (tool_name == NULL ||
+                        gimp_container_get_child_by_name (
+                          tool_group->priv->children, tool_name) != NULL);
+
+      g_free (tool_group->priv->active_tool);
+
+      tool_group->priv->active_tool = g_strdup (tool_name);;
+
+      g_signal_emit (tool_group,
+                     gimp_tool_group_signals[ACTIVE_TOOL_CHANGED], 0);
+
+      g_object_notify (G_OBJECT (tool_group), "active-tool");
+    }
+}
+
+const gchar *
+gimp_tool_group_get_active_tool (GimpToolGroup *tool_group)
+{
+  g_return_val_if_fail (GIMP_IS_TOOL_GROUP (tool_group), NULL);
+
+  return tool_group->priv->active_tool;
+}
+
+void
+gimp_tool_group_set_active_tool_info (GimpToolGroup *tool_group,
+                                      GimpToolInfo  *tool_info)
+{
+  g_return_if_fail (GIMP_IS_TOOL_GROUP (tool_group));
+  g_return_if_fail (tool_info == NULL || GIMP_IS_TOOL_INFO (tool_info));
+
+  gimp_tool_group_set_active_tool (
+    tool_group,
+    tool_info ? gimp_object_get_name (GIMP_OBJECT (tool_info)) : NULL);
+}
+
+GimpToolInfo *
+gimp_tool_group_get_active_tool_info (GimpToolGroup *tool_group)
+{
+  g_return_val_if_fail (GIMP_IS_TOOL_GROUP (tool_group), NULL);
+
+  return GIMP_TOOL_INFO (
+    gimp_container_get_child_by_name (tool_group->priv->children,
+                                      tool_group->priv->active_tool));
+}
diff --git a/app/core/gimptoolgroup.h b/app/core/gimptoolgroup.h
new file mode 100644
index 0000000..ef4d979
--- /dev/null
+++ b/app/core/gimptoolgroup.h
@@ -0,0 +1,68 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimptoolgroup.h
+ * Copyright (C) 2020 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_TOOL_GROUP_H__
+#define __GIMP_TOOL_GROUP_H__
+
+
+#include "gimptoolitem.h"
+
+
+#define GIMP_TYPE_TOOL_GROUP            (gimp_tool_group_get_type ())
+#define GIMP_TOOL_GROUP(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_TOOL_GROUP, GimpToolGroup))
+#define GIMP_TOOL_GROUP_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_TOOL_GROUP, GimpToolGroupClass))
+#define GIMP_IS_TOOL_GROUP(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_TOOL_GROUP))
+#define GIMP_IS_TOOL_GROUP_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_TOOL_GROUP))
+#define GIMP_TOOL_GROUP_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_TOOL_GROUP, GimpToolGroupClass))
+
+
+typedef struct _GimpToolGroupPrivate GimpToolGroupPrivate;
+typedef struct _GimpToolGroupClass   GimpToolGroupClass;
+
+struct _GimpToolGroup
+{
+  GimpToolItem          parent_instance;
+
+  GimpToolGroupPrivate *priv;
+};
+
+struct _GimpToolGroupClass
+{
+  GimpToolItemClass  parent_class;
+
+  /*  signals  */
+  void (* active_tool_changed) (GimpToolGroup *tool_group);
+};
+
+
+GType           gimp_tool_group_get_type             (void) G_GNUC_CONST;
+
+GimpToolGroup * gimp_tool_group_new                  (void);
+
+void            gimp_tool_group_set_active_tool      (GimpToolGroup *tool_group,
+                                                      const gchar   *tool_name);
+const gchar   * gimp_tool_group_get_active_tool      (GimpToolGroup *tool_group);
+
+void            gimp_tool_group_set_active_tool_info (GimpToolGroup *tool_group,
+                                                      GimpToolInfo  *tool_info);
+GimpToolInfo  * gimp_tool_group_get_active_tool_info (GimpToolGroup *tool_group);
+
+
+#endif  /*  __GIMP_TOOL_GROUP_H__  */
diff --git a/app/core/gimptoolinfo.c b/app/core/gimptoolinfo.c
new file mode 100644
index 0000000..34d93c3
--- /dev/null
+++ b/app/core/gimptoolinfo.c
@@ -0,0 +1,263 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+
+#include "core-types.h"
+
+#include "gimp.h"
+#include "gimpdatafactory.h"
+#include "gimpfilteredcontainer.h"
+#include "gimppaintinfo.h"
+#include "gimptoolinfo.h"
+#include "gimptooloptions.h"
+#include "gimptoolpreset.h"
+
+
+static void    gimp_tool_info_dispose         (GObject       *object);
+static void    gimp_tool_info_finalize        (GObject       *object);
+
+static gchar * gimp_tool_info_get_description (GimpViewable  *viewable,
+                                               gchar        **tooltip);
+
+
+G_DEFINE_TYPE (GimpToolInfo, gimp_tool_info, GIMP_TYPE_TOOL_ITEM)
+
+#define parent_class gimp_tool_info_parent_class
+
+
+static void
+gimp_tool_info_class_init (GimpToolInfoClass *klass)
+{
+  GObjectClass      *object_class   = G_OBJECT_CLASS (klass);
+  GimpViewableClass *viewable_class = GIMP_VIEWABLE_CLASS (klass);
+
+  object_class->dispose           = gimp_tool_info_dispose;
+  object_class->finalize          = gimp_tool_info_finalize;
+
+  viewable_class->get_description = gimp_tool_info_get_description;
+}
+
+static void
+gimp_tool_info_init (GimpToolInfo *tool_info)
+{
+}
+
+static void
+gimp_tool_info_dispose (GObject *object)
+{
+  GimpToolInfo *tool_info = GIMP_TOOL_INFO (object);
+
+  if (tool_info->tool_options)
+    {
+      g_object_run_dispose (G_OBJECT (tool_info->tool_options));
+      g_clear_object (&tool_info->tool_options);
+    }
+
+  g_clear_object (&tool_info->presets);
+
+  G_OBJECT_CLASS (parent_class)->dispose (object);
+}
+
+static void
+gimp_tool_info_finalize (GObject *object)
+{
+  GimpToolInfo *tool_info = GIMP_TOOL_INFO (object);
+
+  g_clear_pointer (&tool_info->label,       g_free);
+  g_clear_pointer (&tool_info->tooltip,     g_free);
+  g_clear_pointer (&tool_info->menu_label,  g_free);
+  g_clear_pointer (&tool_info->menu_accel,  g_free);
+  g_clear_pointer (&tool_info->help_domain, g_free);
+  g_clear_pointer (&tool_info->help_id,     g_free);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static gchar *
+gimp_tool_info_get_description (GimpViewable  *viewable,
+                                gchar        **tooltip)
+{
+  GimpToolInfo *tool_info = GIMP_TOOL_INFO (viewable);
+
+  if (tooltip)
+    *tooltip = g_strdup (tool_info->tooltip);
+
+  return g_strdup (tool_info->label);
+}
+
+static gboolean
+gimp_tool_info_filter_preset (GimpObject *object,
+                              gpointer    user_data)
+{
+  GimpToolPreset *preset    = GIMP_TOOL_PRESET (object);
+  GimpToolInfo   *tool_info = user_data;
+
+  return preset->tool_options->tool_info == tool_info;
+}
+
+GimpToolInfo *
+gimp_tool_info_new (Gimp                *gimp,
+                    GType                tool_type,
+                    GType                tool_options_type,
+                    GimpContextPropMask  context_props,
+                    const gchar         *identifier,
+                    const gchar         *label,
+                    const gchar         *tooltip,
+                    const gchar         *menu_label,
+                    const gchar         *menu_accel,
+                    const gchar         *help_domain,
+                    const gchar         *help_id,
+                    const gchar         *paint_core_name,
+                    const gchar         *icon_name)
+{
+  GimpPaintInfo *paint_info;
+  GimpToolInfo  *tool_info;
+
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+  g_return_val_if_fail (identifier != NULL, NULL);
+  g_return_val_if_fail (label != NULL, NULL);
+  g_return_val_if_fail (tooltip != NULL, NULL);
+  g_return_val_if_fail (help_id != NULL, NULL);
+  g_return_val_if_fail (paint_core_name != NULL, NULL);
+  g_return_val_if_fail (icon_name != NULL, NULL);
+
+  paint_info = (GimpPaintInfo *)
+    gimp_container_get_child_by_name (gimp->paint_info_list, paint_core_name);
+
+  g_return_val_if_fail (GIMP_IS_PAINT_INFO (paint_info), NULL);
+
+  tool_info = g_object_new (GIMP_TYPE_TOOL_INFO,
+                            "name",      identifier,
+                            "icon-name", icon_name,
+                            NULL);
+
+  tool_info->gimp              = gimp;
+  tool_info->tool_type         = tool_type;
+  tool_info->tool_options_type = tool_options_type;
+  tool_info->context_props     = context_props;
+
+  tool_info->label             = g_strdup (label);
+  tool_info->tooltip           = g_strdup (tooltip);
+
+  tool_info->menu_label        = g_strdup (menu_label);
+  tool_info->menu_accel        = g_strdup (menu_accel);
+
+  tool_info->help_domain       = g_strdup (help_domain);
+  tool_info->help_id           = g_strdup (help_id);
+
+  tool_info->paint_info        = paint_info;
+
+  if (tool_info->tool_options_type == paint_info->paint_options_type)
+    {
+      tool_info->tool_options = g_object_ref (GIMP_TOOL_OPTIONS (paint_info->paint_options));
+    }
+  else
+    {
+      tool_info->tool_options = g_object_new (tool_info->tool_options_type,
+                                              "gimp", gimp,
+                                              "name", identifier,
+                                              NULL);
+    }
+
+  g_object_set (tool_info->tool_options,
+                "tool",      tool_info,
+                "tool-info", tool_info, NULL);
+
+  gimp_tool_options_set_gui_mode (tool_info->tool_options, TRUE);
+
+  if (tool_info->tool_options_type != GIMP_TYPE_TOOL_OPTIONS)
+    {
+      GimpContainer *presets;
+
+      presets = gimp_data_factory_get_container (gimp->tool_preset_factory);
+
+      tool_info->presets =
+        gimp_filtered_container_new (presets,
+                                     gimp_tool_info_filter_preset,
+                                     tool_info);
+    }
+
+  return tool_info;
+}
+
+void
+gimp_tool_info_set_standard (Gimp         *gimp,
+                             GimpToolInfo *tool_info)
+{
+  g_return_if_fail (GIMP_IS_GIMP (gimp));
+  g_return_if_fail (! tool_info || GIMP_IS_TOOL_INFO (tool_info));
+
+  g_set_object (&gimp->standard_tool_info, tool_info);
+}
+
+GimpToolInfo *
+gimp_tool_info_get_standard (Gimp *gimp)
+{
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  return gimp->standard_tool_info;
+}
+
+gchar *
+gimp_tool_info_get_action_name (GimpToolInfo *tool_info)
+{
+  const gchar *identifier;
+  gchar       *tmp;
+  gchar       *name;
+
+  g_return_val_if_fail (GIMP_IS_TOOL_INFO (tool_info), NULL);
+
+  identifier = gimp_object_get_name (GIMP_OBJECT (tool_info));
+
+  g_return_val_if_fail (g_str_has_prefix (identifier, "gimp-"), NULL);
+  g_return_val_if_fail (g_str_has_suffix (identifier, "-tool"), NULL);
+
+  tmp = g_strndup (identifier + strlen ("gimp-"),
+                    strlen (identifier) - strlen ("gimp--tool"));
+
+  name = g_strdup_printf ("tools-%s", tmp);
+
+  g_free (tmp);
+
+  return name;
+}
+
+GFile *
+gimp_tool_info_get_options_file (GimpToolInfo *tool_info,
+                                 const gchar  *suffix)
+{
+  gchar *basename;
+  GFile *file;
+
+  g_return_val_if_fail (GIMP_IS_TOOL_INFO (tool_info), NULL);
+
+  /* also works for a NULL suffix */
+  basename = g_strconcat (gimp_object_get_name (tool_info), suffix, NULL);
+
+  file = gimp_directory_file ("tool-options", basename, NULL);
+  g_free (basename);
+
+  return file;
+}
diff --git a/app/core/gimptoolinfo.h b/app/core/gimptoolinfo.h
new file mode 100644
index 0000000..fc028b7
--- /dev/null
+++ b/app/core/gimptoolinfo.h
@@ -0,0 +1,95 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_TOOL_INFO_H__
+#define __GIMP_TOOL_INFO_H__
+
+
+#include "gimptoolitem.h"
+
+
+#define GIMP_TYPE_TOOL_INFO            (gimp_tool_info_get_type ())
+#define GIMP_TOOL_INFO(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_TOOL_INFO, GimpToolInfo))
+#define GIMP_TOOL_INFO_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_TOOL_INFO, GimpToolInfoClass))
+#define GIMP_IS_TOOL_INFO(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_TOOL_INFO))
+#define GIMP_IS_TOOL_INFO_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_TOOL_INFO))
+#define GIMP_TOOL_INFO_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_TOOL_INFO, GimpToolInfoClass))
+
+
+typedef struct _GimpToolInfoClass GimpToolInfoClass;
+
+struct _GimpToolInfo
+{
+  GimpToolItem         parent_instance;
+
+  Gimp                *gimp;
+
+  GType                tool_type;
+  GType                tool_options_type;
+  GimpContextPropMask  context_props;
+
+  gchar               *label;
+  gchar               *tooltip;
+
+  gchar               *menu_label;
+  gchar               *menu_accel;
+
+  gchar               *help_domain;
+  gchar               *help_id;
+
+  gboolean             hidden;
+  gboolean             experimental;
+
+  GimpToolOptions     *tool_options;
+  GimpPaintInfo       *paint_info;
+
+  GimpContainer       *presets;
+};
+
+struct _GimpToolInfoClass
+{
+  GimpToolItemClass  parent_class;
+};
+
+
+GType          gimp_tool_info_get_type         (void) G_GNUC_CONST;
+
+GimpToolInfo * gimp_tool_info_new              (Gimp                *gimp,
+                                                GType                tool_type,
+                                                GType                tool_options_type,
+                                                GimpContextPropMask  context_props,
+                                                const gchar         *identifier,
+                                                const gchar         *label,
+                                                const gchar         *tooltip,
+                                                const gchar         *menu_label,
+                                                const gchar         *menu_accel,
+                                                const gchar         *help_domain,
+                                                const gchar         *help_id,
+                                                const gchar         *paint_core_name,
+                                                const gchar         *icon_name);
+
+void           gimp_tool_info_set_standard     (Gimp                *gimp,
+                                                GimpToolInfo        *tool_info);
+GimpToolInfo * gimp_tool_info_get_standard     (Gimp                *gimp);
+
+gchar        * gimp_tool_info_get_action_name (GimpToolInfo         *tool_info);
+
+GFile        * gimp_tool_info_get_options_file (GimpToolInfo        *tool_info,
+                                                const gchar         *suffix);
+
+
+#endif  /*  __GIMP_TOOL_INFO_H__  */
diff --git a/app/core/gimptoolitem.c b/app/core/gimptoolitem.c
new file mode 100644
index 0000000..984597b
--- /dev/null
+++ b/app/core/gimptoolitem.c
@@ -0,0 +1,227 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimptoolitem.c
+ * Copyright (C) 2020 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpconfig/gimpconfig.h"
+
+#include "core-types.h"
+
+#include "core/gimpmarshal.h"
+
+#include "gimptoolitem.h"
+
+
+enum
+{
+  VISIBLE_CHANGED,
+  SHOWN_CHANGED,
+  LAST_SIGNAL
+};
+
+enum
+{
+  PROP_0,
+  PROP_VISIBLE,
+  PROP_SHOWN
+};
+
+
+struct _GimpToolItemPrivate
+{
+  gboolean visible;
+};
+
+
+/*  local function prototypes  */
+
+static void   gimp_tool_item_get_property  (GObject      *object,
+                                            guint         property_id,
+                                            GValue       *value,
+                                            GParamSpec   *pspec);
+static void   gimp_tool_item_set_property  (GObject      *object,
+                                            guint         property_id,
+                                            const GValue *value,
+                                            GParamSpec   *pspec);
+
+
+G_DEFINE_TYPE_WITH_PRIVATE (GimpToolItem, gimp_tool_item, GIMP_TYPE_VIEWABLE)
+
+#define parent_class gimp_tool_item_parent_class
+
+static guint gimp_tool_item_signals[LAST_SIGNAL] = { 0 };
+
+
+/*  private functions  */
+
+static void
+gimp_tool_item_class_init (GimpToolItemClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  gimp_tool_item_signals[VISIBLE_CHANGED] =
+    g_signal_new ("visible-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpToolItemClass, visible_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  gimp_tool_item_signals[SHOWN_CHANGED] =
+    g_signal_new ("shown-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpToolItemClass, shown_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  object_class->get_property = gimp_tool_item_get_property;
+  object_class->set_property = gimp_tool_item_set_property;
+
+  GIMP_CONFIG_PROP_BOOLEAN (object_class, PROP_VISIBLE,
+                            "visible", NULL, NULL,
+                            TRUE,
+                            GIMP_PARAM_STATIC_STRINGS);
+
+  g_object_class_install_property (object_class, PROP_SHOWN,
+                                   g_param_spec_boolean ("shown", NULL, NULL,
+                                                         TRUE,
+                                                         GIMP_PARAM_READABLE));
+}
+
+static void
+gimp_tool_item_init (GimpToolItem *tool_item)
+{
+  tool_item->priv = gimp_tool_item_get_instance_private (tool_item);
+}
+
+static void
+gimp_tool_item_get_property (GObject    *object,
+                             guint       property_id,
+                             GValue     *value,
+                             GParamSpec *pspec)
+{
+  GimpToolItem *tool_item = GIMP_TOOL_ITEM (object);
+
+  switch (property_id)
+    {
+    case PROP_VISIBLE:
+      g_value_set_boolean (value, tool_item->priv->visible);
+      break;
+    case PROP_SHOWN:
+      g_value_set_boolean (value, gimp_tool_item_get_shown (tool_item));
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_tool_item_set_property (GObject      *object,
+                             guint         property_id,
+                             const GValue *value,
+                             GParamSpec   *pspec)
+{
+  GimpToolItem *tool_item = GIMP_TOOL_ITEM (object);
+
+  switch (property_id)
+    {
+    case PROP_VISIBLE:
+      gimp_tool_item_set_visible (tool_item, g_value_get_boolean (value));
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+
+/*  public functions  */
+
+void
+gimp_tool_item_set_visible (GimpToolItem *tool_item,
+                            gboolean      visible)
+{
+  g_return_if_fail (GIMP_IS_TOOL_ITEM (tool_item));
+
+  if (visible != tool_item->priv->visible)
+    {
+      gboolean old_shown;
+
+      g_object_freeze_notify (G_OBJECT (tool_item));
+
+      old_shown = gimp_tool_item_get_shown (tool_item);
+
+      tool_item->priv->visible = visible;
+
+      g_signal_emit (tool_item, gimp_tool_item_signals[VISIBLE_CHANGED], 0);
+
+      if (gimp_tool_item_get_shown (tool_item) != old_shown)
+        gimp_tool_item_shown_changed (tool_item);
+
+      g_object_notify (G_OBJECT (tool_item), "visible");
+
+      g_object_thaw_notify (G_OBJECT (tool_item));
+    }
+}
+
+gboolean
+gimp_tool_item_get_visible (GimpToolItem *tool_item)
+{
+  g_return_val_if_fail (GIMP_IS_TOOL_ITEM (tool_item), FALSE);
+
+  return tool_item->priv->visible;
+}
+
+gboolean
+gimp_tool_item_get_shown (GimpToolItem *tool_item)
+{
+  GimpToolItem *parent;
+
+  g_return_val_if_fail (GIMP_IS_TOOL_ITEM (tool_item), FALSE);
+
+  parent = GIMP_TOOL_ITEM (
+    gimp_viewable_get_parent (GIMP_VIEWABLE (tool_item)));
+
+  return tool_item->priv->visible &&
+         (! parent || gimp_tool_item_get_shown (parent));
+}
+
+
+/*  protected functions  */
+
+void
+gimp_tool_item_shown_changed (GimpToolItem *tool_item)
+{
+  g_signal_emit (tool_item, gimp_tool_item_signals[SHOWN_CHANGED], 0);
+
+  g_object_notify (G_OBJECT (tool_item), "shown");
+}
diff --git a/app/core/gimptoolitem.h b/app/core/gimptoolitem.h
new file mode 100644
index 0000000..3f19f49
--- /dev/null
+++ b/app/core/gimptoolitem.h
@@ -0,0 +1,70 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimptoolitem.h
+ * Copyright (C) 2020 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_TOOL_ITEM_H__
+#define __GIMP_TOOL_ITEM_H__
+
+
+#include "gimpviewable.h"
+
+
+#define GIMP_TYPE_TOOL_ITEM            (gimp_tool_item_get_type ())
+#define GIMP_TOOL_ITEM(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_TOOL_ITEM, GimpToolItem))
+#define GIMP_TOOL_ITEM_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_TOOL_ITEM, GimpToolItemClass))
+#define GIMP_IS_TOOL_ITEM(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_TOOL_ITEM))
+#define GIMP_IS_TOOL_ITEM_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_TOOL_ITEM))
+#define GIMP_TOOL_ITEM_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_TOOL_ITEM, GimpToolItemClass))
+
+
+typedef struct _GimpToolItemPrivate GimpToolItemPrivate;
+typedef struct _GimpToolItemClass   GimpToolItemClass;
+
+struct _GimpToolItem
+{
+  GimpViewable         parent_instance;
+
+  GimpToolItemPrivate *priv;
+};
+
+struct _GimpToolItemClass
+{
+  GimpViewableClass  parent_class;
+
+  /*  signals  */
+  void (* visible_changed) (GimpToolItem *tool_item);
+  void (* shown_changed)   (GimpToolItem *tool_item);
+};
+
+
+GType      gimp_tool_item_get_type      (void) G_GNUC_CONST;
+                                        
+void       gimp_tool_item_set_visible   (GimpToolItem *tool_item,
+                                         gboolean      visible);
+gboolean   gimp_tool_item_get_visible   (GimpToolItem *tool_item);
+                                        
+gboolean   gimp_tool_item_get_shown     (GimpToolItem *tool_item);
+
+
+/*  protected  */
+
+void       gimp_tool_item_shown_changed (GimpToolItem *tool_item);
+
+
+#endif  /*  __GIMP_TOOL_ITEM_H__  */
diff --git a/app/core/gimptooloptions.c b/app/core/gimptooloptions.c
new file mode 100644
index 0000000..8a19d6e
--- /dev/null
+++ b/app/core/gimptooloptions.c
@@ -0,0 +1,378 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1999 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpconfig/gimpconfig.h"
+
+#include "core-types.h"
+
+#include "gimp.h"
+#include "gimperror.h"
+#include "gimptoolinfo.h"
+#include "gimptooloptions.h"
+
+#include "gimp-intl.h"
+
+
+enum
+{
+  PROP_0,
+  PROP_TOOL,
+  PROP_TOOL_INFO
+};
+
+
+static void   gimp_tool_options_config_iface_init (GimpConfigInterface *iface);
+
+static void   gimp_tool_options_dispose           (GObject         *object);
+static void   gimp_tool_options_set_property      (GObject         *object,
+                                                   guint            property_id,
+                                                   const GValue    *value,
+                                                   GParamSpec      *pspec);
+static void   gimp_tool_options_get_property      (GObject         *object,
+                                                   guint            property_id,
+                                                   GValue          *value,
+                                                   GParamSpec      *pspec);
+
+static void   gimp_tool_options_config_reset      (GimpConfig      *config);
+
+static void   gimp_tool_options_tool_notify       (GimpToolOptions *options,
+                                                   GParamSpec      *pspec);
+
+
+G_DEFINE_TYPE_WITH_CODE (GimpToolOptions, gimp_tool_options, GIMP_TYPE_CONTEXT,
+                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_CONFIG,
+                                                gimp_tool_options_config_iface_init))
+
+#define parent_class gimp_tool_options_parent_class
+
+
+static void
+gimp_tool_options_class_init (GimpToolOptionsClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  object_class->dispose      = gimp_tool_options_dispose;
+  object_class->set_property = gimp_tool_options_set_property;
+  object_class->get_property = gimp_tool_options_get_property;
+
+  g_object_class_override_property (object_class, PROP_TOOL, "tool");
+
+  g_object_class_install_property (object_class, PROP_TOOL_INFO,
+                                   g_param_spec_object ("tool-info",
+                                                        NULL, NULL,
+                                                        GIMP_TYPE_TOOL_INFO,
+                                                        GIMP_PARAM_READWRITE));
+
+}
+
+static void
+gimp_tool_options_init (GimpToolOptions *options)
+{
+  options->tool_info = NULL;
+
+  g_signal_connect (options, "notify::tool",
+                    G_CALLBACK (gimp_tool_options_tool_notify),
+                    NULL);
+}
+
+static void
+gimp_tool_options_config_iface_init (GimpConfigInterface *iface)
+{
+  iface->reset = gimp_tool_options_config_reset;
+}
+
+static void
+gimp_tool_options_dispose (GObject *object)
+{
+  GimpToolOptions *options = GIMP_TOOL_OPTIONS (object);
+
+  g_clear_object (&options->tool_info);
+
+  G_OBJECT_CLASS (parent_class)->dispose (object);
+}
+
+/*  This is such a horrible hack, but necessary because we
+ *  a) load an option's tool-info from disk in many cases
+ *  b) screwed up in the past and saved the wrong tool-info in some cases
+ */
+static GimpToolInfo *
+gimp_tool_options_check_tool_info (GimpToolOptions *options,
+                                   GimpToolInfo    *tool_info,
+                                   gboolean         warn)
+{
+  if (tool_info && G_OBJECT_TYPE (options) == tool_info->tool_options_type)
+    {
+      return tool_info;
+    }
+  else
+    {
+      GList *list;
+
+      for (list = gimp_get_tool_info_iter (GIMP_CONTEXT (options)->gimp);
+           list;
+           list = g_list_next (list))
+        {
+          GimpToolInfo *new_info = list->data;
+
+          if (G_OBJECT_TYPE (options) == new_info->tool_options_type)
+            {
+              if (warn)
+                g_printerr ("%s: correcting bogus deserialized tool "
+                            "type '%s' with right type '%s'\n",
+                            g_type_name (G_OBJECT_TYPE (options)),
+                            tool_info ? gimp_object_get_name (tool_info) : "NULL",
+                            gimp_object_get_name (new_info));
+
+              return new_info;
+            }
+        }
+
+      g_return_val_if_reached (NULL);
+    }
+}
+
+static void
+gimp_tool_options_set_property (GObject      *object,
+                                guint         property_id,
+                                const GValue *value,
+                                GParamSpec   *pspec)
+{
+  GimpToolOptions *options = GIMP_TOOL_OPTIONS (object);
+
+  switch (property_id)
+    {
+    case PROP_TOOL:
+      {
+        GimpToolInfo *tool_info = g_value_get_object (value);
+        GimpToolInfo *context_tool;
+
+        context_tool = gimp_context_get_tool (GIMP_CONTEXT (options));
+
+        g_return_if_fail (context_tool == NULL ||
+                          context_tool == tool_info);
+
+        tool_info = gimp_tool_options_check_tool_info (options, tool_info, TRUE);
+
+        if (! context_tool)
+          gimp_context_set_tool (GIMP_CONTEXT (options), tool_info);
+      }
+      break;
+
+    case PROP_TOOL_INFO:
+      {
+        GimpToolInfo *tool_info = g_value_get_object (value);
+
+        g_return_if_fail (options->tool_info == NULL ||
+                          options->tool_info == tool_info);
+
+        tool_info = gimp_tool_options_check_tool_info (options, tool_info, TRUE);
+
+        if (! options->tool_info)
+          {
+            options->tool_info = g_object_ref (tool_info);
+
+            gimp_context_set_serialize_properties (GIMP_CONTEXT (options),
+                                                   tool_info->context_props);
+          }
+      }
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_tool_options_get_property (GObject    *object,
+                                guint       property_id,
+                                GValue     *value,
+                                GParamSpec *pspec)
+{
+  GimpToolOptions *options = GIMP_TOOL_OPTIONS (object);
+
+  switch (property_id)
+    {
+    case PROP_TOOL:
+      g_value_set_object (value, gimp_context_get_tool (GIMP_CONTEXT (options)));
+      break;
+
+    case PROP_TOOL_INFO:
+      g_value_set_object (value, options->tool_info);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_tool_options_config_reset (GimpConfig *config)
+{
+  gchar *name = g_strdup (gimp_object_get_name (config));
+
+  gimp_config_reset_properties (G_OBJECT (config));
+
+  gimp_object_take_name (GIMP_OBJECT (config), name);
+}
+
+static void
+gimp_tool_options_tool_notify (GimpToolOptions *options,
+                               GParamSpec      *pspec)
+{
+  GimpToolInfo *tool_info = gimp_context_get_tool (GIMP_CONTEXT (options));
+  GimpToolInfo *new_info;
+
+  new_info = gimp_tool_options_check_tool_info (options, tool_info, FALSE);
+
+  if (tool_info && new_info != tool_info)
+    g_warning ("%s: 'tool' property on %s was set to bogus value "
+               "'%s', it MUST be '%s'.",
+               G_STRFUNC,
+               g_type_name (G_OBJECT_TYPE (options)),
+               gimp_object_get_name (tool_info),
+               gimp_object_get_name (new_info));
+}
+
+
+/*  public functions  */
+
+void
+gimp_tool_options_set_gui_mode (GimpToolOptions *tool_options,
+                                gboolean         gui_mode)
+{
+  g_return_if_fail (GIMP_IS_TOOL_OPTIONS (tool_options));
+
+  tool_options->gui_mode = gui_mode ? TRUE : FALSE;
+}
+
+gboolean
+gimp_tool_options_get_gui_mode (GimpToolOptions *tool_options)
+{
+  g_return_val_if_fail (GIMP_IS_TOOL_OPTIONS (tool_options), FALSE);
+
+  return tool_options->gui_mode;
+}
+
+gboolean
+gimp_tool_options_serialize (GimpToolOptions  *tool_options,
+                             GError          **error)
+{
+  GFile    *file;
+  gchar    *header;
+  gchar    *footer;
+  gboolean  retval;
+
+  g_return_val_if_fail (GIMP_IS_TOOL_OPTIONS (tool_options), FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  file = gimp_tool_info_get_options_file (tool_options->tool_info, NULL);
+
+  if (tool_options->tool_info->gimp->be_verbose)
+    g_print ("Writing '%s'\n", gimp_file_get_utf8_name (file));
+
+  header = g_strdup_printf ("GIMP %s options",
+                            gimp_object_get_name (tool_options->tool_info));
+  footer = g_strdup_printf ("end of %s options",
+                            gimp_object_get_name (tool_options->tool_info));
+
+  retval = gimp_config_serialize_to_gfile (GIMP_CONFIG (tool_options),
+                                           file,
+                                           header, footer,
+                                           NULL,
+                                           error);
+
+  g_free (header);
+  g_free (footer);
+
+  g_object_unref (file);
+
+  return retval;
+}
+
+gboolean
+gimp_tool_options_deserialize (GimpToolOptions  *tool_options,
+                               GError          **error)
+{
+  GFile    *file;
+  gboolean  retval;
+
+  g_return_val_if_fail (GIMP_IS_TOOL_OPTIONS (tool_options), FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  file = gimp_tool_info_get_options_file (tool_options->tool_info, NULL);
+
+  if (tool_options->tool_info->gimp->be_verbose)
+    g_print ("Parsing '%s'\n", gimp_file_get_utf8_name (file));
+
+  retval = gimp_config_deserialize_gfile (GIMP_CONFIG (tool_options),
+                                          file,
+                                          NULL,
+                                          error);
+
+  g_object_unref (file);
+
+  return retval;
+}
+
+gboolean
+gimp_tool_options_delete (GimpToolOptions  *tool_options,
+                          GError          **error)
+{
+  GFile    *file;
+  GError   *my_error = NULL;
+  gboolean  success  = TRUE;
+
+  g_return_val_if_fail (GIMP_IS_TOOL_OPTIONS (tool_options), FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  file = gimp_tool_info_get_options_file (tool_options->tool_info, NULL);
+
+  if (tool_options->tool_info->gimp->be_verbose)
+    g_print ("Deleting '%s'\n", gimp_file_get_utf8_name (file));
+
+  if (! g_file_delete (file, NULL, &my_error) &&
+      my_error->code != G_IO_ERROR_NOT_FOUND)
+    {
+      success = FALSE;
+
+      g_set_error (error, GIMP_ERROR, GIMP_FAILED,
+                   _("Deleting \"%s\" failed: %s"),
+                   gimp_file_get_utf8_name (file), my_error->message);
+    }
+
+  g_clear_error (&my_error);
+  g_object_unref (file);
+
+  return success;
+}
+
+void
+gimp_tool_options_create_folder (void)
+{
+  GFile *file = gimp_directory_file ("tool-options", NULL);
+
+  g_file_make_directory (file, NULL, NULL);
+  g_object_unref (file);
+}
diff --git a/app/core/gimptooloptions.h b/app/core/gimptooloptions.h
new file mode 100644
index 0000000..f59aa52
--- /dev/null
+++ b/app/core/gimptooloptions.h
@@ -0,0 +1,73 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1999 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_TOOL_OPTIONS_H__
+#define __GIMP_TOOL_OPTIONS_H__
+
+
+#include "gimpcontext.h"
+
+
+#define GIMP_TYPE_TOOL_OPTIONS            (gimp_tool_options_get_type ())
+#define GIMP_TOOL_OPTIONS(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_TOOL_OPTIONS, GimpToolOptions))
+#define GIMP_TOOL_OPTIONS_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_TOOL_OPTIONS, GimpToolOptionsClass))
+#define GIMP_IS_TOOL_OPTIONS(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_TOOL_OPTIONS))
+#define GIMP_IS_TOOL_OPTIONS_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_TOOL_OPTIONS))
+#define GIMP_TOOL_OPTIONS_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_TOOL_OPTIONS, GimpToolOptionsClass))
+
+
+typedef struct _GimpToolOptionsClass GimpToolOptionsClass;
+
+struct _GimpToolOptions
+{
+  GimpContext   parent_instance;
+
+  GimpToolInfo *tool_info;
+
+  /*  if TRUE this instance is the main tool options object used for
+   *  the GUI, this is not exactly clean, but there are some things
+   *  (like linking brush properties to the active brush, or properly
+   *  maintaining global brush, pattern etc.) that can only be done
+   *  right in the object, and not by signal connections from the GUI,
+   *  or upon switching tools, all of which was much more horrible.
+   */
+  gboolean      gui_mode;
+};
+
+struct _GimpToolOptionsClass
+{
+  GimpContextClass parent_class;
+};
+
+
+GType      gimp_tool_options_get_type      (void) G_GNUC_CONST;
+
+void       gimp_tool_options_set_gui_mode  (GimpToolOptions   *tool_options,
+                                            gboolean           gui_mode);
+gboolean   gimp_tool_options_get_gui_mode  (GimpToolOptions   *tool_options);
+
+gboolean   gimp_tool_options_serialize     (GimpToolOptions   *tool_options,
+                                            GError           **error);
+gboolean   gimp_tool_options_deserialize   (GimpToolOptions   *tool_options,
+                                            GError           **error);
+
+gboolean   gimp_tool_options_delete        (GimpToolOptions   *tool_options,
+                                            GError           **error);
+void       gimp_tool_options_create_folder (void);
+
+
+#endif  /*  __GIMP_TOOL_OPTIONS_H__  */
diff --git a/app/core/gimptoolpreset-load.c b/app/core/gimptoolpreset-load.c
new file mode 100644
index 0000000..386ac09
--- /dev/null
+++ b/app/core/gimptoolpreset-load.c
@@ -0,0 +1,71 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpconfig/gimpconfig.h"
+
+#include "core-types.h"
+
+#include "gimpcontext.h"
+#include "gimptoolpreset.h"
+#include "gimptoolpreset-load.h"
+
+#include "gimp-intl.h"
+
+
+GList *
+gimp_tool_preset_load (GimpContext   *context,
+                       GFile         *file,
+                       GInputStream  *input,
+                       GError       **error)
+{
+  GimpToolPreset *tool_preset;
+
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+  g_return_val_if_fail (G_IS_FILE (file), NULL);
+  g_return_val_if_fail (G_IS_INPUT_STREAM (input), NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, NULL);
+
+  tool_preset = g_object_new (GIMP_TYPE_TOOL_PRESET,
+                              "gimp", context->gimp,
+                              NULL);
+
+  if (gimp_config_deserialize_stream (GIMP_CONFIG (tool_preset),
+                                      input,
+                                      NULL, error))
+    {
+      if (GIMP_IS_CONTEXT (tool_preset->tool_options))
+        {
+          return g_list_prepend (NULL, tool_preset);
+        }
+      else
+        {
+          g_set_error_literal (error,
+                               GIMP_CONFIG_ERROR, GIMP_CONFIG_ERROR_PARSE,
+                               _("Tool preset file is corrupt."));
+        }
+    }
+
+  g_object_unref (tool_preset);
+
+  return NULL;
+}
diff --git a/app/core/gimptoolpreset-load.h b/app/core/gimptoolpreset-load.h
new file mode 100644
index 0000000..9a016df
--- /dev/null
+++ b/app/core/gimptoolpreset-load.h
@@ -0,0 +1,31 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_TOOL_PRESET_LOAD_H__
+#define __GIMP_TOOL_PRESET_LOAD_H__
+
+
+#define GIMP_TOOL_PRESET_FILE_EXTENSION ".gtp"
+
+
+GList * gimp_tool_preset_load (GimpContext   *context,
+                               GFile         *file,
+                               GInputStream  *input,
+                               GError       **error);
+
+
+#endif /* __GIMP_TOOL_PRESET_LOAD_H__ */
diff --git a/app/core/gimptoolpreset-save.c b/app/core/gimptoolpreset-save.c
new file mode 100644
index 0000000..0afd024
--- /dev/null
+++ b/app/core/gimptoolpreset-save.c
@@ -0,0 +1,44 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpconfig/gimpconfig.h"
+
+#include "core-types.h"
+
+#include "gimptoolpreset.h"
+#include "gimptoolpreset-save.h"
+
+
+gboolean
+gimp_tool_preset_save (GimpData       *data,
+                       GOutputStream  *output,
+                       GError        **error)
+{
+  g_return_val_if_fail (GIMP_IS_TOOL_PRESET (data), FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  return gimp_config_serialize_to_stream (GIMP_CONFIG (data),
+                                          output,
+                                          "GIMP tool preset file",
+                                          "end of GIMP tool preset file",
+                                          NULL, error);
+}
diff --git a/app/core/gimptoolpreset-save.h b/app/core/gimptoolpreset-save.h
new file mode 100644
index 0000000..d78ef64
--- /dev/null
+++ b/app/core/gimptoolpreset-save.h
@@ -0,0 +1,28 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_TOOL_PRESET_SAVE_H__
+#define __GIMP_TOOL_PRESET_SAVE_H__
+
+
+/*  don't call this function directly, use gimp_data_save() instead  */
+gboolean   gimp_tool_preset_save (GimpData       *data,
+                                  GOutputStream  *output,
+                                  GError        **error);
+
+
+#endif /* __GIMP_TOOL_PRESET_SAVE_H__ */
diff --git a/app/core/gimptoolpreset.c b/app/core/gimptoolpreset.c
new file mode 100644
index 0000000..6ab2eb7
--- /dev/null
+++ b/app/core/gimptoolpreset.c
@@ -0,0 +1,705 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1999 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpmath/gimpmath.h"
+#include "libgimpconfig/gimpconfig.h"
+
+#include "core-types.h"
+
+#include "gimp.h"
+#include "gimptoolinfo.h"
+#include "gimptooloptions.h"
+#include "gimptoolpreset.h"
+#include "gimptoolpreset-load.h"
+#include "gimptoolpreset-save.h"
+
+#include "gimp-intl.h"
+
+
+/*  The defaults are "everything except color", which is problematic
+ *  with gradients, which is why we special case the gradient tool in
+ *  gimp_tool_preset_set_options().
+ */
+#define DEFAULT_USE_FG_BG              FALSE
+#define DEFAULT_USE_OPACITY_PAINT_MODE TRUE
+#define DEFAULT_USE_BRUSH              TRUE
+#define DEFAULT_USE_DYNAMICS           TRUE
+#define DEFAULT_USE_MYBRUSH            TRUE
+#define DEFAULT_USE_GRADIENT           FALSE
+#define DEFAULT_USE_PATTERN            TRUE
+#define DEFAULT_USE_PALETTE            FALSE
+#define DEFAULT_USE_FONT               TRUE
+
+enum
+{
+  PROP_0,
+  PROP_NAME,
+  PROP_GIMP,
+  PROP_TOOL_OPTIONS,
+  PROP_USE_FG_BG,
+  PROP_USE_OPACITY_PAINT_MODE,
+  PROP_USE_BRUSH,
+  PROP_USE_DYNAMICS,
+  PROP_USE_MYBRUSH,
+  PROP_USE_GRADIENT,
+  PROP_USE_PATTERN,
+  PROP_USE_PALETTE,
+  PROP_USE_FONT
+};
+
+
+static void          gimp_tool_preset_config_iface_init    (GimpConfigInterface *iface);
+
+static void          gimp_tool_preset_constructed          (GObject          *object);
+static void          gimp_tool_preset_finalize             (GObject          *object);
+static void          gimp_tool_preset_set_property         (GObject          *object,
+                                                            guint             property_id,
+                                                            const GValue     *value,
+                                                            GParamSpec       *pspec);
+static void          gimp_tool_preset_get_property         (GObject          *object,
+                                                            guint             property_id,
+                                                            GValue           *value,
+                                                            GParamSpec       *pspec);
+static void
+             gimp_tool_preset_dispatch_properties_changed  (GObject          *object,
+                                                            guint             n_pspecs,
+                                                            GParamSpec      **pspecs);
+
+static const gchar * gimp_tool_preset_get_extension        (GimpData         *data);
+
+static gboolean      gimp_tool_preset_deserialize_property (GimpConfig       *config,
+                                                            guint             property_id,
+                                                            GValue           *value,
+                                                            GParamSpec       *pspec,
+                                                            GScanner         *scanner,
+                                                            GTokenType       *expected);
+
+static void          gimp_tool_preset_set_options          (GimpToolPreset   *preset,
+                                                            GimpToolOptions  *options);
+static void          gimp_tool_preset_options_notify       (GObject          *tool_options,
+                                                            const GParamSpec *pspec,
+                                                            GimpToolPreset   *preset);
+static void     gimp_tool_preset_options_prop_name_changed (GimpContext         *tool_options,
+                                                            GimpContextPropType  prop,
+                                                            GimpToolPreset      *preset);
+
+
+G_DEFINE_TYPE_WITH_CODE (GimpToolPreset, gimp_tool_preset, GIMP_TYPE_DATA,
+                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_CONFIG,
+                                                gimp_tool_preset_config_iface_init))
+
+#define parent_class gimp_tool_preset_parent_class
+
+
+static void
+gimp_tool_preset_class_init (GimpToolPresetClass *klass)
+{
+  GObjectClass  *object_class = G_OBJECT_CLASS (klass);
+  GimpDataClass *data_class   = GIMP_DATA_CLASS (klass);
+
+  object_class->constructed                 = gimp_tool_preset_constructed;
+  object_class->finalize                    = gimp_tool_preset_finalize;
+  object_class->set_property                = gimp_tool_preset_set_property;
+  object_class->get_property                = gimp_tool_preset_get_property;
+  object_class->dispatch_properties_changed = gimp_tool_preset_dispatch_properties_changed;
+
+  data_class->save                          = gimp_tool_preset_save;
+  data_class->get_extension                 = gimp_tool_preset_get_extension;
+
+  GIMP_CONFIG_PROP_STRING (object_class, PROP_NAME,
+                           "name",
+                           NULL, NULL,
+                           "Unnamed",
+                           GIMP_PARAM_STATIC_STRINGS);
+
+  g_object_class_install_property (object_class, PROP_GIMP,
+                                   g_param_spec_object ("gimp",
+                                                        NULL, NULL,
+                                                        GIMP_TYPE_GIMP,
+                                                        GIMP_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT_ONLY));
+
+  GIMP_CONFIG_PROP_OBJECT (object_class, PROP_TOOL_OPTIONS,
+                           "tool-options",
+                           NULL, NULL,
+                           GIMP_TYPE_TOOL_OPTIONS,
+                           GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_BOOLEAN (object_class, PROP_USE_FG_BG,
+                            "use-fg-bg",
+                            _("Apply stored FG/BG"),
+                            NULL,
+                            DEFAULT_USE_FG_BG,
+                            GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_BOOLEAN (object_class, PROP_USE_OPACITY_PAINT_MODE,
+                            "use-opacity-paint-mode",
+                            _("Apply stored opacity/paint mode"),
+                            NULL,
+                            DEFAULT_USE_OPACITY_PAINT_MODE,
+                            GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_BOOLEAN (object_class, PROP_USE_BRUSH,
+                            "use-brush",
+                            _("Apply stored brush"),
+                            NULL,
+                            DEFAULT_USE_BRUSH,
+                            GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_BOOLEAN (object_class, PROP_USE_DYNAMICS,
+                            "use-dynamics",
+                            _("Apply stored dynamics"),
+                            NULL,
+                            DEFAULT_USE_DYNAMICS,
+                            GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_BOOLEAN (object_class, PROP_USE_MYBRUSH,
+                            "use-mypaint-brush",
+                            _("Apply stored MyPaint brush"),
+                            NULL,
+                            DEFAULT_USE_MYBRUSH,
+                            GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_BOOLEAN (object_class, PROP_USE_PATTERN,
+                            "use-pattern",
+                            _("Apply stored pattern"),
+                            NULL,
+                            DEFAULT_USE_PATTERN,
+                            GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_BOOLEAN (object_class, PROP_USE_PALETTE,
+                            "use-palette",
+                            _("Apply stored palette"),
+                            NULL,
+                            DEFAULT_USE_PALETTE,
+                            GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_BOOLEAN (object_class, PROP_USE_GRADIENT,
+                            "use-gradient",
+                            _("Apply stored gradient"),
+                            NULL,
+                            DEFAULT_USE_GRADIENT,
+                            GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_BOOLEAN (object_class, PROP_USE_FONT,
+                            "use-font",
+                            _("Apply stored font"),
+                            NULL,
+                            DEFAULT_USE_FONT,
+                            GIMP_PARAM_STATIC_STRINGS);
+}
+
+static void
+gimp_tool_preset_config_iface_init (GimpConfigInterface *iface)
+{
+  iface->deserialize_property = gimp_tool_preset_deserialize_property;
+}
+
+static void
+gimp_tool_preset_init (GimpToolPreset *tool_preset)
+{
+}
+
+static void
+gimp_tool_preset_constructed (GObject *object)
+{
+  GimpToolPreset *preset = GIMP_TOOL_PRESET (object);
+
+  G_OBJECT_CLASS (parent_class)->constructed (object);
+
+  g_return_if_fail (GIMP_IS_GIMP (preset->gimp));
+}
+
+static void
+gimp_tool_preset_finalize (GObject *object)
+{
+  GimpToolPreset *tool_preset = GIMP_TOOL_PRESET (object);
+
+  gimp_tool_preset_set_options (tool_preset, NULL);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gimp_tool_preset_set_property (GObject      *object,
+                               guint         property_id,
+                               const GValue *value,
+                               GParamSpec   *pspec)
+{
+  GimpToolPreset *tool_preset = GIMP_TOOL_PRESET (object);
+
+  switch (property_id)
+    {
+    case PROP_NAME:
+      gimp_object_set_name (GIMP_OBJECT (tool_preset),
+                            g_value_get_string (value));
+      break;
+
+    case PROP_GIMP:
+      tool_preset->gimp = g_value_get_object (value); /* don't ref */
+      break;
+
+    case PROP_TOOL_OPTIONS:
+      gimp_tool_preset_set_options (tool_preset,
+                                    GIMP_TOOL_OPTIONS (g_value_get_object (value)));
+      break;
+
+    case PROP_USE_FG_BG:
+      tool_preset->use_fg_bg = g_value_get_boolean (value);
+      break;
+    case PROP_USE_OPACITY_PAINT_MODE:
+      tool_preset->use_opacity_paint_mode = g_value_get_boolean (value);
+      break;
+    case PROP_USE_BRUSH:
+      tool_preset->use_brush = g_value_get_boolean (value);
+      break;
+    case PROP_USE_DYNAMICS:
+      tool_preset->use_dynamics = g_value_get_boolean (value);
+      break;
+    case PROP_USE_MYBRUSH:
+      tool_preset->use_mybrush = g_value_get_boolean (value);
+      break;
+    case PROP_USE_PATTERN:
+      tool_preset->use_pattern = g_value_get_boolean (value);
+      break;
+    case PROP_USE_PALETTE:
+      tool_preset->use_palette = g_value_get_boolean (value);
+      break;
+    case PROP_USE_GRADIENT:
+      tool_preset->use_gradient = g_value_get_boolean (value);
+      break;
+    case PROP_USE_FONT:
+      tool_preset->use_font = g_value_get_boolean (value);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_tool_preset_get_property (GObject    *object,
+                               guint       property_id,
+                               GValue     *value,
+                               GParamSpec *pspec)
+{
+  GimpToolPreset *tool_preset = GIMP_TOOL_PRESET (object);
+
+  switch (property_id)
+    {
+    case PROP_NAME:
+      g_value_set_string (value, gimp_object_get_name (tool_preset));
+      break;
+
+    case PROP_GIMP:
+      g_value_set_object (value, tool_preset->gimp);
+      break;
+
+    case PROP_TOOL_OPTIONS:
+      g_value_set_object (value, tool_preset->tool_options);
+      break;
+
+    case PROP_USE_FG_BG:
+      g_value_set_boolean (value, tool_preset->use_fg_bg);
+      break;
+    case PROP_USE_OPACITY_PAINT_MODE:
+      g_value_set_boolean (value, tool_preset->use_opacity_paint_mode);
+      break;
+    case PROP_USE_BRUSH:
+      g_value_set_boolean (value, tool_preset->use_brush);
+      break;
+    case PROP_USE_MYBRUSH:
+      g_value_set_boolean (value, tool_preset->use_mybrush);
+      break;
+    case PROP_USE_DYNAMICS:
+      g_value_set_boolean (value, tool_preset->use_dynamics);
+      break;
+    case PROP_USE_PATTERN:
+      g_value_set_boolean (value, tool_preset->use_pattern);
+      break;
+    case PROP_USE_PALETTE:
+      g_value_set_boolean (value, tool_preset->use_palette);
+      break;
+    case PROP_USE_GRADIENT:
+      g_value_set_boolean (value, tool_preset->use_gradient);
+      break;
+    case PROP_USE_FONT:
+      g_value_set_boolean (value, tool_preset->use_font);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_tool_preset_dispatch_properties_changed (GObject     *object,
+                                              guint        n_pspecs,
+                                              GParamSpec **pspecs)
+{
+  gint i;
+
+  G_OBJECT_CLASS (parent_class)->dispatch_properties_changed (object,
+                                                              n_pspecs, pspecs);
+
+  for (i = 0; i < n_pspecs; i++)
+    {
+      if (pspecs[i]->flags & GIMP_CONFIG_PARAM_SERIALIZE)
+        {
+          gimp_data_dirty (GIMP_DATA (object));
+          break;
+        }
+    }
+}
+
+static const gchar *
+gimp_tool_preset_get_extension (GimpData *data)
+{
+  return GIMP_TOOL_PRESET_FILE_EXTENSION;
+}
+
+static gboolean
+gimp_tool_preset_deserialize_property (GimpConfig *config,
+                                       guint       property_id,
+                                       GValue     *value,
+                                       GParamSpec *pspec,
+                                       GScanner   *scanner,
+                                       GTokenType *expected)
+{
+  GimpToolPreset *tool_preset = GIMP_TOOL_PRESET (config);
+
+  switch (property_id)
+    {
+    case PROP_TOOL_OPTIONS:
+      {
+        GObject             *options;
+        gchar               *type_name;
+        GType                type;
+        GimpContextPropMask  serialize_props;
+
+        if (! gimp_scanner_parse_string (scanner, &type_name))
+          {
+            *expected = G_TOKEN_STRING;
+            break;
+          }
+
+        if (! (type_name && *type_name))
+          {
+            g_scanner_error (scanner, "GimpToolOptions type name is empty");
+            *expected = G_TOKEN_NONE;
+            g_free (type_name);
+            break;
+          }
+
+        if (! strcmp (type_name, "GimpTransformOptions"))
+          {
+            g_printerr ("Correcting tool options type GimpTransformOptions "
+                        "to GimpTransformGridOptions\n");
+            g_free (type_name);
+            type_name = g_strdup ("GimpTransformGridOptions");
+          }
+
+        type = g_type_from_name (type_name);
+
+        if (! type)
+          {
+            g_scanner_error (scanner,
+                             "unable to determine type of '%s'",
+                             type_name);
+            *expected = G_TOKEN_NONE;
+            g_free (type_name);
+            break;
+          }
+
+        if (! g_type_is_a (type, GIMP_TYPE_TOOL_OPTIONS))
+          {
+            g_scanner_error (scanner,
+                             "'%s' is not a subclass of GimpToolOptions",
+                             type_name);
+            *expected = G_TOKEN_NONE;
+            g_free (type_name);
+            break;
+          }
+
+        g_free (type_name);
+
+        options = g_object_new (type,
+                                "gimp", tool_preset->gimp,
+                                NULL);
+
+        /*  Initialize all GimpContext object properties that can be
+         *  used by presets with some non-NULL object, so loading a
+         *  broken preset won't leave us with NULL objects that have
+         *  bad effects. See bug #742159.
+         */
+        gimp_context_copy_properties (gimp_get_user_context (tool_preset->gimp),
+                                      GIMP_CONTEXT (options),
+                                      GIMP_CONTEXT_PROP_MASK_BRUSH    |
+                                      GIMP_CONTEXT_PROP_MASK_DYNAMICS |
+                                      GIMP_CONTEXT_PROP_MASK_MYBRUSH  |
+                                      GIMP_CONTEXT_PROP_MASK_PATTERN  |
+                                      GIMP_CONTEXT_PROP_MASK_GRADIENT |
+                                      GIMP_CONTEXT_PROP_MASK_PALETTE  |
+                                      GIMP_CONTEXT_PROP_MASK_FONT);
+
+        if (! GIMP_CONFIG_GET_INTERFACE (options)->deserialize (GIMP_CONFIG (options),
+                                                                scanner, 1,
+                                                                NULL))
+          {
+            *expected = G_TOKEN_NONE;
+            g_object_unref (options);
+            break;
+          }
+
+        /* we need both tool and tool-info on the options */
+        if (gimp_context_get_tool (GIMP_CONTEXT (options)))
+          {
+            g_object_set (options,
+                          "tool-info",
+                          gimp_context_get_tool (GIMP_CONTEXT (options)),
+                          NULL);
+          }
+        else if (GIMP_TOOL_OPTIONS (options)->tool_info)
+          {
+            g_object_set (options,
+                          "tool", GIMP_TOOL_OPTIONS (options)->tool_info,
+                          NULL);
+          }
+        else
+          {
+            /* if we have none, the options set_property() logic will
+             * replace the NULL with its best guess
+             */
+            g_object_set (options,
+                          "tool",      NULL,
+                          "tool-info", NULL,
+                          NULL);
+          }
+
+        serialize_props =
+          gimp_context_get_serialize_properties (GIMP_CONTEXT (options));
+
+        gimp_context_set_serialize_properties (GIMP_CONTEXT (options),
+                                               serialize_props |
+                                               GIMP_CONTEXT_PROP_MASK_TOOL);
+
+        g_value_take_object (value, options);
+      }
+      break;
+
+    default:
+      return FALSE;
+    }
+
+  return TRUE;
+}
+
+static void
+gimp_tool_preset_set_options (GimpToolPreset  *preset,
+                              GimpToolOptions *options)
+{
+  if (preset->tool_options)
+    {
+      g_signal_handlers_disconnect_by_func (preset->tool_options,
+                                            gimp_tool_preset_options_notify,
+                                            preset);
+
+      g_signal_handlers_disconnect_by_func (preset->tool_options,
+                                            gimp_tool_preset_options_prop_name_changed,
+                                            preset);
+
+      g_clear_object (&preset->tool_options);
+    }
+
+  if (options)
+    {
+      GimpContextPropMask serialize_props;
+
+      preset->tool_options =
+        GIMP_TOOL_OPTIONS (gimp_config_duplicate (GIMP_CONFIG (options)));
+
+      serialize_props =
+        gimp_context_get_serialize_properties (GIMP_CONTEXT (preset->tool_options));
+
+      gimp_context_set_serialize_properties (GIMP_CONTEXT (preset->tool_options),
+                                             serialize_props |
+                                             GIMP_CONTEXT_PROP_MASK_TOOL);
+
+      if (! (serialize_props & GIMP_CONTEXT_PROP_MASK_FOREGROUND) &&
+          ! (serialize_props & GIMP_CONTEXT_PROP_MASK_BACKGROUND))
+        g_object_set (preset, "use-fg-bg", FALSE, NULL);
+
+      if (! (serialize_props & GIMP_CONTEXT_PROP_MASK_OPACITY) &&
+          ! (serialize_props & GIMP_CONTEXT_PROP_MASK_PAINT_MODE))
+        g_object_set (preset, "use-opacity-paint-mode", FALSE, NULL);
+
+      if (! (serialize_props & GIMP_CONTEXT_PROP_MASK_BRUSH))
+        g_object_set (preset, "use-brush", FALSE, NULL);
+
+      if (! (serialize_props & GIMP_CONTEXT_PROP_MASK_DYNAMICS))
+        g_object_set (preset, "use-dynamics", FALSE, NULL);
+
+      if (! (serialize_props & GIMP_CONTEXT_PROP_MASK_MYBRUSH))
+        g_object_set (preset, "use-mypaint-brush", FALSE, NULL);
+
+      if (! (serialize_props & GIMP_CONTEXT_PROP_MASK_GRADIENT))
+        g_object_set (preset, "use-gradient", FALSE, NULL);
+
+      if (! (serialize_props & GIMP_CONTEXT_PROP_MASK_PATTERN))
+        g_object_set (preset, "use-pattern", FALSE, NULL);
+
+      if (! (serialize_props & GIMP_CONTEXT_PROP_MASK_PALETTE))
+        g_object_set (preset, "use-palette", FALSE, NULL);
+
+      if (! (serialize_props & GIMP_CONTEXT_PROP_MASK_FONT))
+        g_object_set (preset, "use-font", FALSE, NULL);
+
+      /*  see comment above the DEFAULT defines at the top of the file  */
+      if (! g_strcmp0 ("gimp-gradient-tool",
+                       gimp_object_get_name (preset->tool_options->tool_info)))
+        g_object_set (preset, "use-gradient", TRUE, NULL);
+
+      g_signal_connect (preset->tool_options, "notify",
+                        G_CALLBACK (gimp_tool_preset_options_notify),
+                        preset);
+
+      g_signal_connect (preset->tool_options, "prop-name-changed",
+                        G_CALLBACK (gimp_tool_preset_options_prop_name_changed),
+                        preset);
+    }
+
+  g_object_notify (G_OBJECT (preset), "tool-options");
+}
+
+static void
+gimp_tool_preset_options_notify (GObject          *tool_options,
+                                 const GParamSpec *pspec,
+                                 GimpToolPreset   *preset)
+{
+  if (pspec->owner_type == GIMP_TYPE_CONTEXT)
+    {
+      GimpContextPropMask serialize_props;
+
+      serialize_props =
+        gimp_context_get_serialize_properties (GIMP_CONTEXT (tool_options));
+
+      if ((1 << pspec->param_id) & serialize_props)
+        {
+          g_object_notify (G_OBJECT (preset), "tool-options");
+        }
+    }
+  else if (pspec->flags & GIMP_CONFIG_PARAM_SERIALIZE)
+    {
+      g_object_notify (G_OBJECT (preset), "tool-options");
+    }
+}
+
+static void
+gimp_tool_preset_options_prop_name_changed (GimpContext         *tool_options,
+                                            GimpContextPropType  prop,
+                                            GimpToolPreset      *preset)
+{
+  GimpContextPropMask serialize_props;
+
+  serialize_props =
+    gimp_context_get_serialize_properties (GIMP_CONTEXT (preset->tool_options));
+
+  if ((1 << prop) & serialize_props)
+    {
+      g_object_notify (G_OBJECT (preset), "tool-options");
+    }
+}
+
+
+/*  public functions  */
+
+GimpData *
+gimp_tool_preset_new (GimpContext *context,
+                      const gchar *unused)
+{
+  GimpToolInfo *tool_info;
+  const gchar  *icon_name;
+
+  g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+
+  tool_info = gimp_context_get_tool (context);
+
+  g_return_val_if_fail (tool_info != NULL, NULL);
+
+  icon_name = gimp_viewable_get_icon_name (GIMP_VIEWABLE (tool_info));
+
+  return g_object_new (GIMP_TYPE_TOOL_PRESET,
+                       "name",         tool_info->label,
+                       "icon-name",    icon_name,
+                       "gimp",         context->gimp,
+                       "tool-options", tool_info->tool_options,
+                       NULL);
+}
+
+GimpContextPropMask
+gimp_tool_preset_get_prop_mask (GimpToolPreset *preset)
+{
+  GimpContextPropMask serialize_props;
+  GimpContextPropMask use_props = 0;
+
+  g_return_val_if_fail (GIMP_IS_TOOL_PRESET (preset), 0);
+
+  serialize_props =
+    gimp_context_get_serialize_properties (GIMP_CONTEXT (preset->tool_options));
+
+  if (preset->use_fg_bg)
+    {
+      use_props |= (GIMP_CONTEXT_PROP_MASK_FOREGROUND & serialize_props);
+      use_props |= (GIMP_CONTEXT_PROP_MASK_BACKGROUND & serialize_props);
+    }
+
+  if (preset->use_opacity_paint_mode)
+    {
+      use_props |= (GIMP_CONTEXT_PROP_MASK_OPACITY    & serialize_props);
+      use_props |= (GIMP_CONTEXT_PROP_MASK_PAINT_MODE & serialize_props);
+    }
+
+  if (preset->use_brush)
+    use_props |= (GIMP_CONTEXT_PROP_MASK_BRUSH & serialize_props);
+
+  if (preset->use_dynamics)
+    use_props |= (GIMP_CONTEXT_PROP_MASK_DYNAMICS & serialize_props);
+
+  if (preset->use_mybrush)
+    use_props |= (GIMP_CONTEXT_PROP_MASK_MYBRUSH & serialize_props);
+
+  if (preset->use_pattern)
+    use_props |= (GIMP_CONTEXT_PROP_MASK_PATTERN & serialize_props);
+
+  if (preset->use_palette)
+    use_props |= (GIMP_CONTEXT_PROP_MASK_PALETTE & serialize_props);
+
+  if (preset->use_gradient)
+    use_props |= (GIMP_CONTEXT_PROP_MASK_GRADIENT & serialize_props);
+
+  if (preset->use_font)
+    use_props |= (GIMP_CONTEXT_PROP_MASK_FONT & serialize_props);
+
+  return use_props;
+}
diff --git a/app/core/gimptoolpreset.h b/app/core/gimptoolpreset.h
new file mode 100644
index 0000000..bf2cceb
--- /dev/null
+++ b/app/core/gimptoolpreset.h
@@ -0,0 +1,67 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1999 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_TOOL_PRESET_H__
+#define __GIMP_TOOL_PRESET_H__
+
+
+#include "gimpdata.h"
+
+
+#define GIMP_TYPE_TOOL_PRESET            (gimp_tool_preset_get_type ())
+#define GIMP_TOOL_PRESET(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_TOOL_PRESET, GimpToolPreset))
+#define GIMP_TOOL_PRESET_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_TOOL_PRESET, GimpToolPresetClass))
+#define GIMP_IS_TOOL_PRESET(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_TOOL_PRESET))
+#define GIMP_IS_TOOL_PRESET_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_TOOL_PRESET))
+#define GIMP_TOOL_PRESET_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_TOOL_PRESET, GimpToolPresetClass))
+
+
+typedef struct _GimpToolPresetClass GimpToolPresetClass;
+
+struct _GimpToolPreset
+{
+  GimpData         parent_instance;
+
+  Gimp            *gimp;
+  GimpToolOptions *tool_options;
+
+  gboolean         use_fg_bg;
+  gboolean         use_opacity_paint_mode;
+  gboolean         use_brush;
+  gboolean         use_dynamics;
+  gboolean         use_mybrush;
+  gboolean         use_gradient;
+  gboolean         use_pattern;
+  gboolean         use_palette;
+  gboolean         use_font;
+};
+
+struct _GimpToolPresetClass
+{
+  GimpDataClass  parent_class;
+};
+
+
+GType                 gimp_tool_preset_get_type      (void) G_GNUC_CONST;
+
+GimpData            * gimp_tool_preset_new           (GimpContext    *context,
+                                                      const gchar    *unused);
+
+GimpContextPropMask   gimp_tool_preset_get_prop_mask (GimpToolPreset *preset);
+
+
+#endif  /*  __GIMP_TOOL_PRESET_H__  */
diff --git a/app/core/gimptreehandler.c b/app/core/gimptreehandler.c
new file mode 100644
index 0000000..b26768e
--- /dev/null
+++ b/app/core/gimptreehandler.c
@@ -0,0 +1,238 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * GimpTreeHandler
+ * Copyright (C) 2009  Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gimpcontainer.h"
+#include "gimptreehandler.h"
+#include "gimpviewable.h"
+
+
+static void   gimp_tree_handler_dispose          (GObject         *object);
+
+static void   gimp_tree_handler_freeze           (GimpTreeHandler *handler,
+                                                  GimpContainer   *container);
+static void   gimp_tree_handler_thaw             (GimpTreeHandler *handler,
+                                                  GimpContainer   *container);
+
+static void   gimp_tree_handler_add_container    (GimpTreeHandler *handler,
+                                                  GimpContainer   *container);
+static void   gimp_tree_handler_add_foreach      (GimpViewable    *viewable,
+                                                  GimpTreeHandler *handler);
+static void   gimp_tree_handler_add              (GimpTreeHandler *handler,
+                                                  GimpViewable    *viewable,
+                                                  GimpContainer   *container);
+
+static void   gimp_tree_handler_remove_container (GimpTreeHandler *handler,
+                                                  GimpContainer   *container);
+static void   gimp_tree_handler_remove_foreach   (GimpViewable    *viewable,
+                                                  GimpTreeHandler *handler);
+static void   gimp_tree_handler_remove           (GimpTreeHandler *handler,
+                                                  GimpViewable    *viewable,
+                                                  GimpContainer   *container);
+
+
+G_DEFINE_TYPE (GimpTreeHandler, gimp_tree_handler, GIMP_TYPE_OBJECT)
+
+#define parent_class gimp_tree_handler_parent_class
+
+
+static void
+gimp_tree_handler_class_init (GimpTreeHandlerClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  object_class->dispose = gimp_tree_handler_dispose;
+}
+
+static void
+gimp_tree_handler_init (GimpTreeHandler *handler)
+{
+}
+
+static void
+gimp_tree_handler_dispose (GObject *object)
+{
+  GimpTreeHandler *handler = GIMP_TREE_HANDLER (object);
+
+  if (handler->container)
+    {
+      g_signal_handlers_disconnect_by_func (handler->container,
+                                            gimp_tree_handler_freeze,
+                                            handler);
+      g_signal_handlers_disconnect_by_func (handler->container,
+                                            gimp_tree_handler_thaw,
+                                            handler);
+
+      if (! gimp_container_frozen (handler->container))
+        gimp_tree_handler_remove_container (handler, handler->container);
+
+      g_clear_object (&handler->container);
+      g_clear_pointer (&handler->signal_name, g_free);
+    }
+
+  G_OBJECT_CLASS (parent_class)->dispose (object);
+}
+
+
+/*  public functions  */
+
+GimpTreeHandler *
+gimp_tree_handler_connect (GimpContainer *container,
+                           const gchar   *signal_name,
+                           GCallback      callback,
+                           gpointer       user_data)
+{
+  GimpTreeHandler *handler;
+
+  g_return_val_if_fail (GIMP_IS_CONTAINER (container), NULL);
+  g_return_val_if_fail (signal_name != NULL, NULL);
+
+  handler = g_object_new (GIMP_TYPE_TREE_HANDLER, NULL);
+
+  handler->container   = g_object_ref (container);
+  handler->signal_name = g_strdup (signal_name);
+  handler->callback    = callback;
+  handler->user_data   = user_data;
+
+  if (! gimp_container_frozen (container))
+    gimp_tree_handler_add_container (handler, container);
+
+  g_signal_connect_object (container, "freeze",
+                           G_CALLBACK (gimp_tree_handler_freeze),
+                           handler,
+                           G_CONNECT_SWAPPED);
+  g_signal_connect_object (container, "thaw",
+                           G_CALLBACK (gimp_tree_handler_thaw),
+                           handler,
+                           G_CONNECT_SWAPPED);
+
+  return handler;
+}
+
+void
+gimp_tree_handler_disconnect (GimpTreeHandler *handler)
+{
+  g_return_if_fail (GIMP_IS_TREE_HANDLER (handler));
+
+  g_object_run_dispose (G_OBJECT (handler));
+  g_object_unref (handler);
+}
+
+
+/*  private functions  */
+
+static void
+gimp_tree_handler_freeze (GimpTreeHandler *handler,
+                          GimpContainer   *container)
+{
+  gimp_tree_handler_remove_container (handler, container);
+}
+
+static void
+gimp_tree_handler_thaw (GimpTreeHandler *handler,
+                        GimpContainer   *container)
+{
+  gimp_tree_handler_add_container (handler, container);
+}
+
+static void
+gimp_tree_handler_add_container (GimpTreeHandler *handler,
+                                 GimpContainer   *container)
+{
+  gimp_container_foreach (container,
+                          (GFunc) gimp_tree_handler_add_foreach,
+                          handler);
+
+  g_signal_connect_object (container, "add",
+                           G_CALLBACK (gimp_tree_handler_add),
+                           handler,
+                           G_CONNECT_SWAPPED);
+  g_signal_connect_object (container, "remove",
+                           G_CALLBACK (gimp_tree_handler_remove),
+                           handler,
+                           G_CONNECT_SWAPPED);
+}
+
+static void
+gimp_tree_handler_add_foreach (GimpViewable    *viewable,
+                               GimpTreeHandler *handler)
+{
+  gimp_tree_handler_add (handler, viewable, NULL);
+}
+
+static void
+gimp_tree_handler_add (GimpTreeHandler *handler,
+                       GimpViewable    *viewable,
+                       GimpContainer   *unused)
+{
+  GimpContainer *children = gimp_viewable_get_children (viewable);
+
+  g_signal_connect (viewable,
+                    handler->signal_name,
+                    handler->callback,
+                    handler->user_data);
+
+  if (children)
+    gimp_tree_handler_add_container (handler, children);
+}
+
+static void
+gimp_tree_handler_remove_container (GimpTreeHandler *handler,
+                                    GimpContainer   *container)
+{
+  g_signal_handlers_disconnect_by_func (container,
+                                        gimp_tree_handler_add,
+                                        handler);
+  g_signal_handlers_disconnect_by_func (container,
+                                        gimp_tree_handler_remove,
+                                        handler);
+
+  gimp_container_foreach (container,
+                          (GFunc) gimp_tree_handler_remove_foreach,
+                          handler);
+}
+
+static void
+gimp_tree_handler_remove_foreach (GimpViewable    *viewable,
+                                  GimpTreeHandler *handler)
+{
+  gimp_tree_handler_remove (handler, viewable, NULL);
+}
+
+static void
+gimp_tree_handler_remove (GimpTreeHandler *handler,
+                          GimpViewable    *viewable,
+                          GimpContainer   *unused)
+{
+  GimpContainer *children = gimp_viewable_get_children (viewable);
+
+  if (children)
+    gimp_tree_handler_remove_container (handler, children);
+
+  g_signal_handlers_disconnect_by_func (viewable,
+                                        handler->callback,
+                                        handler->user_data);
+}
diff --git a/app/core/gimptreehandler.h b/app/core/gimptreehandler.h
new file mode 100644
index 0000000..27497c4
--- /dev/null
+++ b/app/core/gimptreehandler.h
@@ -0,0 +1,64 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * GimpTreeHandler
+ * Copyright (C) 2009  Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_TREE_HANDLER_H__
+#define __GIMP_TREE_HANDLER_H__
+
+
+#include "core/gimpobject.h"
+
+
+#define GIMP_TYPE_TREE_HANDLER            (gimp_tree_handler_get_type ())
+#define GIMP_TREE_HANDLER(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_TREE_HANDLER, GimpTreeHandler))
+#define GIMP_TREE_HANDLER_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_TREE_HANDLER, GimpTreeHandlerClass))
+#define GIMP_IS_TREE_HANDLER(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_TREE_HANDLER))
+#define GIMP_IS_TREE_HANDLER_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_TREE_HANDLER))
+#define GIMP_TREE_HANDLER_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_TREE_HANDLER, GimpTreeHandlerClass))
+
+
+typedef struct _GimpTreeHandlerClass GimpTreeHandlerClass;
+
+struct _GimpTreeHandler
+{
+  GimpObject     parent_instance;
+
+  GimpContainer *container;
+
+  gchar         *signal_name;
+  GCallback      callback;
+  gpointer       user_data;
+};
+
+struct _GimpTreeHandlerClass
+{
+  GimpObjectClass  parent_class;
+};
+
+
+GType             gimp_tree_handler_get_type   (void) G_GNUC_CONST;
+
+GimpTreeHandler * gimp_tree_handler_connect    (GimpContainer   *container,
+                                                const gchar     *signal_name,
+                                                GCallback        callback,
+                                                gpointer         user_data);
+void              gimp_tree_handler_disconnect (GimpTreeHandler *handler);
+
+
+#endif /* __GIMP_TREE_HANDLER_H__ */
diff --git a/app/core/gimptreeproxy.c b/app/core/gimptreeproxy.c
new file mode 100644
index 0000000..76fad91
--- /dev/null
+++ b/app/core/gimptreeproxy.c
@@ -0,0 +1,634 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimptreeproxy.c
+ * Copyright (C) 2020 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+
+#include "core-types.h"
+
+#include "gimpviewable.h"
+#include "gimptreeproxy.h"
+
+
+enum
+{
+  PROP_0,
+  PROP_CONTAINER,
+  PROP_FLAT
+};
+
+
+struct _GimpTreeProxyPrivate
+{
+  GimpContainer *container;
+  gboolean       flat;
+};
+
+
+/*  local function prototypes  */
+
+static void   gimp_tree_proxy_dispose             (GObject      *object);
+static void   gimp_tree_proxy_set_property        (GObject      *object,
+                                                   guint         property_id,
+                                                   const GValue *value,
+                                                   GParamSpec   *pspec);
+static void   gimp_tree_proxy_get_property        (GObject      *object,
+                                                   guint         property_id,
+                                                   GValue       *value,
+                                                   GParamSpec   *pspec);
+
+static void   gimp_tree_proxy_container_add       (GimpContainer *container,
+                                                   GimpObject    *object,
+                                                   GimpTreeProxy *tree_proxy);
+static void   gimp_tree_proxy_container_remove    (GimpContainer *container,
+                                                   GimpObject    *object,
+                                                   GimpTreeProxy *tree_proxy);
+static void   gimp_tree_proxy_container_reorder   (GimpContainer *container,
+                                                   GimpObject    *object,
+                                                   gint           new_index,
+                                                   GimpTreeProxy *tree_proxy);
+static void   gimp_tree_proxy_container_freeze    (GimpContainer *container,
+                                                   GimpTreeProxy *tree_proxy);
+static void   gimp_tree_proxy_container_thaw      (GimpContainer *container,
+                                                   GimpTreeProxy *tree_proxy);
+
+static gint   gimp_tree_proxy_add_container       (GimpTreeProxy *tree_proxy,
+                                                   GimpContainer *container,
+                                                   gint           index);
+static void   gimp_tree_proxy_remove_container    (GimpTreeProxy *tree_proxy,
+                                                   GimpContainer *container);
+
+static gint   gimp_tree_proxy_add_object          (GimpTreeProxy *tree_proxy,
+                                                   GimpObject    *object,
+                                                   gint           index);
+static void   gimp_tree_proxy_remove_object       (GimpTreeProxy *tree_proxy,
+                                                   GimpObject    *object);
+
+static gint   gimp_tree_proxy_find_container      (GimpTreeProxy *tree_proxy,
+                                                   GimpContainer *container);
+static gint   gimp_tree_proxy_find_object         (GimpContainer *container,
+                                                   GimpObject    *object);
+
+
+G_DEFINE_TYPE_WITH_PRIVATE (GimpTreeProxy, gimp_tree_proxy, GIMP_TYPE_LIST)
+
+#define parent_class gimp_tree_proxy_parent_class
+
+
+/*  private functions  */
+
+static void
+gimp_tree_proxy_class_init (GimpTreeProxyClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  object_class->dispose      = gimp_tree_proxy_dispose;
+  object_class->set_property = gimp_tree_proxy_set_property;
+  object_class->get_property = gimp_tree_proxy_get_property;
+
+  g_object_class_install_property (object_class, PROP_CONTAINER,
+                                   g_param_spec_object ("container", NULL, NULL,
+                                                        GIMP_TYPE_CONTAINER,
+                                                        GIMP_PARAM_READWRITE));
+
+  g_object_class_install_property (object_class, PROP_FLAT,
+                                   g_param_spec_boolean ("flat", NULL, NULL,
+                                                         FALSE,
+                                                         GIMP_PARAM_READWRITE));
+}
+
+static void
+gimp_tree_proxy_init (GimpTreeProxy *tree_proxy)
+{
+  tree_proxy->priv = gimp_tree_proxy_get_instance_private (tree_proxy);
+}
+
+static void
+gimp_tree_proxy_dispose (GObject *object)
+{
+  GimpTreeProxy *tree_proxy = GIMP_TREE_PROXY (object);
+
+  gimp_tree_proxy_set_container (tree_proxy, NULL);
+
+  G_OBJECT_CLASS (parent_class)->dispose (object);;
+}
+
+static void
+gimp_tree_proxy_set_property (GObject      *object,
+                             guint         property_id,
+                             const GValue *value,
+                             GParamSpec   *pspec)
+{
+  GimpTreeProxy *tree_proxy = GIMP_TREE_PROXY (object);
+
+  switch (property_id)
+    {
+    case PROP_CONTAINER:
+      gimp_tree_proxy_set_container (tree_proxy, g_value_get_object (value));
+      break;
+
+    case PROP_FLAT:
+      gimp_tree_proxy_set_flat (tree_proxy, g_value_get_boolean (value));
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_tree_proxy_get_property (GObject    *object,
+                             guint       property_id,
+                             GValue     *value,
+                             GParamSpec *pspec)
+{
+  GimpTreeProxy *tree_proxy = GIMP_TREE_PROXY (object);
+
+  switch (property_id)
+    {
+    case PROP_CONTAINER:
+      g_value_set_object (value, tree_proxy->priv->container);
+      break;
+
+    case PROP_FLAT:
+      g_value_set_boolean (value, tree_proxy->priv->flat);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_tree_proxy_container_add (GimpContainer *container,
+                               GimpObject    *object,
+                               GimpTreeProxy *tree_proxy)
+{
+  gint index;
+
+  if (tree_proxy->priv->flat)
+    {
+      index = gimp_tree_proxy_find_container (tree_proxy, container) +
+              gimp_tree_proxy_find_object    (container,  object);
+    }
+  else
+    {
+      index = gimp_container_get_child_index (container, object);
+    }
+
+  gimp_tree_proxy_add_object (tree_proxy, object, index);
+}
+
+static void
+gimp_tree_proxy_container_remove (GimpContainer *container,
+                                  GimpObject    *object,
+                                  GimpTreeProxy *tree_proxy)
+{
+  gimp_tree_proxy_remove_object (tree_proxy, object);
+}
+
+static void
+gimp_tree_proxy_container_reorder (GimpContainer *container,
+                                   GimpObject    *object,
+                                   gint           new_index,
+                                   GimpTreeProxy *tree_proxy)
+{
+  gint index;
+
+  if (tree_proxy->priv->flat)
+    {
+      index = gimp_tree_proxy_find_container (tree_proxy, container) +
+              gimp_tree_proxy_find_object    (container,  object);
+
+      if (gimp_viewable_get_children (GIMP_VIEWABLE (object)))
+        {
+          gimp_container_freeze (GIMP_CONTAINER (tree_proxy));
+
+          gimp_tree_proxy_remove_object (tree_proxy, object);
+          gimp_tree_proxy_add_object    (tree_proxy, object, index);
+
+          gimp_container_thaw (GIMP_CONTAINER (tree_proxy));
+
+          return;
+        }
+    }
+  else
+    {
+      index = new_index;
+    }
+
+  gimp_container_reorder (GIMP_CONTAINER (tree_proxy), object, index);
+}
+
+static void
+gimp_tree_proxy_container_freeze (GimpContainer *container,
+                                  GimpTreeProxy *tree_proxy)
+{
+  gimp_container_freeze (GIMP_CONTAINER (tree_proxy));
+}
+
+static void
+gimp_tree_proxy_container_thaw (GimpContainer *container,
+                                GimpTreeProxy *tree_proxy)
+{
+  gimp_container_thaw (GIMP_CONTAINER (tree_proxy));
+}
+
+typedef struct
+{
+  GimpTreeProxy *tree_proxy;
+  gint           index;
+} AddContainerData;
+
+static void
+gimp_tree_proxy_add_container_func (GimpObject       *object,
+                                    AddContainerData *data)
+{
+  data->index = gimp_tree_proxy_add_object (data->tree_proxy,
+                                            object, data->index);
+}
+
+static gint
+gimp_tree_proxy_add_container (GimpTreeProxy *tree_proxy,
+                               GimpContainer *container,
+                               gint           index)
+{
+  AddContainerData data;
+
+  g_signal_connect (container, "add",
+                    G_CALLBACK (gimp_tree_proxy_container_add),
+                    tree_proxy);
+  g_signal_connect (container, "remove",
+                    G_CALLBACK (gimp_tree_proxy_container_remove),
+                    tree_proxy);
+  g_signal_connect (container, "reorder",
+                    G_CALLBACK (gimp_tree_proxy_container_reorder),
+                    tree_proxy);
+  g_signal_connect (container, "freeze",
+                    G_CALLBACK (gimp_tree_proxy_container_freeze),
+                    tree_proxy);
+  g_signal_connect (container, "thaw",
+                    G_CALLBACK (gimp_tree_proxy_container_thaw),
+                    tree_proxy);
+
+  data.tree_proxy = tree_proxy;
+  data.index      = index;
+
+  gimp_container_freeze (GIMP_CONTAINER (tree_proxy));
+
+  gimp_container_foreach (container,
+                          (GFunc) gimp_tree_proxy_add_container_func,
+                          &data);
+
+  gimp_container_thaw (GIMP_CONTAINER (tree_proxy));
+
+  return data.index;
+}
+
+static void
+gimp_tree_proxy_remove_container_func (GimpObject    *object,
+                                       GimpTreeProxy *tree_proxy)
+{
+  gimp_tree_proxy_remove_object (tree_proxy, object);
+}
+
+static void
+gimp_tree_proxy_remove_container (GimpTreeProxy *tree_proxy,
+                                  GimpContainer *container)
+{
+  gimp_container_freeze (GIMP_CONTAINER (tree_proxy));
+
+  gimp_container_foreach (container,
+                          (GFunc) gimp_tree_proxy_remove_container_func,
+                          tree_proxy);
+
+  gimp_container_thaw (GIMP_CONTAINER (tree_proxy));
+
+  g_signal_handlers_disconnect_by_func (
+    container,
+    gimp_tree_proxy_container_add,
+    tree_proxy);
+  g_signal_handlers_disconnect_by_func (
+    container,
+    gimp_tree_proxy_container_remove,
+    tree_proxy);
+  g_signal_handlers_disconnect_by_func (
+    container,
+    gimp_tree_proxy_container_reorder,
+    tree_proxy);
+  g_signal_handlers_disconnect_by_func (
+    container,
+    gimp_tree_proxy_container_freeze,
+    tree_proxy);
+  g_signal_handlers_disconnect_by_func (
+    container,
+    gimp_tree_proxy_container_thaw,
+    tree_proxy);
+}
+
+static gint
+gimp_tree_proxy_add_object (GimpTreeProxy *tree_proxy,
+                            GimpObject    *object,
+                            gint           index)
+{
+  if (index == gimp_container_get_n_children (GIMP_CONTAINER (tree_proxy)))
+    index = -1;
+
+  if (tree_proxy->priv->flat)
+    {
+      GimpContainer *children;
+
+      children = gimp_viewable_get_children (GIMP_VIEWABLE (object));
+
+      if (children)
+        return gimp_tree_proxy_add_container (tree_proxy, children, index);
+    }
+
+  if (index >= 0)
+    {
+      gimp_container_insert (GIMP_CONTAINER (tree_proxy), object, index);
+
+      return index + 1;
+    }
+  else
+    {
+      gimp_container_add (GIMP_CONTAINER (tree_proxy), object);
+
+      return index;
+    }
+}
+
+static void
+gimp_tree_proxy_remove_object (GimpTreeProxy *tree_proxy,
+                               GimpObject    *object)
+{
+  if (tree_proxy->priv->flat)
+    {
+      GimpContainer *children;
+
+      children = gimp_viewable_get_children (GIMP_VIEWABLE (object));
+
+      if (children)
+        return gimp_tree_proxy_remove_container (tree_proxy, children);
+    }
+
+  gimp_container_remove (GIMP_CONTAINER (tree_proxy), object);
+}
+
+typedef struct
+{
+  GimpContainer *container;
+  gint           index;
+} FindContainerData;
+
+static gboolean
+gimp_tree_proxy_find_container_search_func (GimpObject        *object,
+                                            FindContainerData *data)
+{
+  GimpContainer *children;
+
+  children = gimp_viewable_get_children (GIMP_VIEWABLE (object));
+
+  if (children)
+    {
+      if (children == data->container)
+        return TRUE;
+
+      return gimp_container_search (
+        children,
+        (GimpContainerSearchFunc) gimp_tree_proxy_find_container_search_func,
+        data) != NULL;
+    }
+
+  data->index++;
+
+  return FALSE;
+}
+
+static gint
+gimp_tree_proxy_find_container (GimpTreeProxy *tree_proxy,
+                                GimpContainer *container)
+{
+  FindContainerData data;
+
+  if (container == tree_proxy->priv->container)
+    return 0;
+
+  data.container = container;
+  data.index     = 0;
+
+  if (gimp_container_search (
+        tree_proxy->priv->container,
+        (GimpContainerSearchFunc) gimp_tree_proxy_find_container_search_func,
+        &data))
+    {
+      return data.index;
+    }
+
+  g_return_val_if_reached (0);
+}
+
+typedef struct
+{
+  GimpObject *object;
+  gint        index;
+} FindObjectData;
+
+static gboolean
+gimp_tree_proxy_find_object_search_func (GimpObject     *object,
+                                         FindObjectData *data)
+{
+  GimpContainer *children;
+
+  if (object == data->object)
+    return TRUE;
+
+  children = gimp_viewable_get_children (GIMP_VIEWABLE (object));
+
+  if (children)
+    {
+      return gimp_container_search (
+        children,
+        (GimpContainerSearchFunc) gimp_tree_proxy_find_object_search_func,
+        data) != NULL;
+    }
+
+  data->index++;
+
+  return FALSE;
+}
+
+static gint
+gimp_tree_proxy_find_object (GimpContainer *container,
+                             GimpObject    *object)
+{
+  FindObjectData data;
+
+  data.object = object;
+  data.index  = 0;
+
+  if (gimp_container_search (
+        container,
+        (GimpContainerSearchFunc) gimp_tree_proxy_find_object_search_func,
+        &data))
+    {
+      return data.index;
+    }
+
+  g_return_val_if_reached (0);
+}
+
+
+/*  public functions  */
+
+GimpContainer *
+gimp_tree_proxy_new (GType children_type)
+{
+  GTypeClass *children_class;
+
+  children_class = g_type_class_ref (children_type);
+
+  g_return_val_if_fail (G_TYPE_CHECK_CLASS_TYPE (children_class,
+                                                 GIMP_TYPE_VIEWABLE),
+                        NULL);
+
+  g_type_class_unref (children_class);
+
+  return g_object_new (GIMP_TYPE_TREE_PROXY,
+                       "children-type", children_type,
+                       "policy",        GIMP_CONTAINER_POLICY_WEAK,
+                       "append",        TRUE,
+                       NULL);
+}
+
+GimpContainer *
+gimp_tree_proxy_new_for_container (GimpContainer *container)
+{
+  GimpTreeProxy *tree_proxy;
+
+  g_return_val_if_fail (GIMP_IS_CONTAINER (container), NULL);
+
+  tree_proxy = GIMP_TREE_PROXY (
+    gimp_tree_proxy_new (gimp_container_get_children_type (container)));
+
+  gimp_tree_proxy_set_container (tree_proxy, container);
+
+  return GIMP_CONTAINER (tree_proxy);
+}
+
+void
+gimp_tree_proxy_set_container (GimpTreeProxy *tree_proxy,
+                               GimpContainer *container)
+{
+  g_return_if_fail (GIMP_IS_TREE_PROXY (tree_proxy));
+  g_return_if_fail (container == NULL || GIMP_IS_CONTAINER (container));
+
+  if (container)
+    {
+      GTypeClass *children_class;
+
+      children_class = g_type_class_ref (
+        gimp_container_get_children_type (container));
+
+      g_return_if_fail (
+        G_TYPE_CHECK_CLASS_TYPE (
+          children_class,
+          gimp_container_get_children_type (GIMP_CONTAINER (tree_proxy))));
+
+      g_type_class_unref (children_class);
+    }
+
+  if (container != tree_proxy->priv->container)
+    {
+      gimp_container_freeze (GIMP_CONTAINER (tree_proxy));
+
+      if (tree_proxy->priv->container)
+        {
+          gimp_tree_proxy_remove_container (tree_proxy,
+                                            tree_proxy->priv->container);
+        }
+
+      g_set_object (&tree_proxy->priv->container, container);
+
+      if (tree_proxy->priv->container)
+        {
+          gimp_tree_proxy_add_container (tree_proxy,
+                                         tree_proxy->priv->container,
+                                         -1);
+        }
+
+      gimp_container_thaw (GIMP_CONTAINER (tree_proxy));
+
+      g_object_notify (G_OBJECT (tree_proxy), "container");
+    }
+}
+
+GimpContainer *
+gimp_tree_proxy_get_container (GimpTreeProxy *tree_proxy)
+{
+  g_return_val_if_fail (GIMP_IS_TREE_PROXY (tree_proxy), NULL);
+
+  return tree_proxy->priv->container;
+}
+
+void
+gimp_tree_proxy_set_flat (GimpTreeProxy *tree_proxy,
+                          gboolean       flat)
+{
+  g_return_if_fail (GIMP_IS_TREE_PROXY (tree_proxy));
+
+  if (flat != tree_proxy->priv->flat)
+    {
+      gimp_container_freeze (GIMP_CONTAINER (tree_proxy));
+
+      if (tree_proxy->priv->container)
+        {
+          gimp_tree_proxy_remove_container (tree_proxy,
+                                            tree_proxy->priv->container);
+        }
+
+      tree_proxy->priv->flat = flat;
+
+      if (tree_proxy->priv->container)
+        {
+          gimp_tree_proxy_add_container (tree_proxy,
+                                         tree_proxy->priv->container,
+                                         -1);
+        }
+
+      gimp_container_thaw (GIMP_CONTAINER (tree_proxy));
+
+      g_object_notify (G_OBJECT (tree_proxy), "flat");
+    }
+}
+
+gboolean
+gimp_tree_proxy_get_flat (GimpTreeProxy *tree_proxy)
+{
+  g_return_val_if_fail (GIMP_IS_TREE_PROXY (tree_proxy), FALSE);
+
+  return tree_proxy->priv->flat;
+}
diff --git a/app/core/gimptreeproxy.h b/app/core/gimptreeproxy.h
new file mode 100644
index 0000000..8ae39f8
--- /dev/null
+++ b/app/core/gimptreeproxy.h
@@ -0,0 +1,66 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimptreeproxy.h
+ * Copyright (C) 2020 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_TREE_PROXY_H__
+#define __GIMP_TREE_PROXY_H__
+
+
+#include "gimplist.h"
+
+
+#define GIMP_TYPE_TREE_PROXY            (gimp_tree_proxy_get_type ())
+#define GIMP_TREE_PROXY(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_TREE_PROXY, GimpTreeProxy))
+#define GIMP_TREE_PROXY_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_TREE_PROXY, GimpTreeProxyClass))
+#define GIMP_IS_TREE_PROXY(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_TREE_PROXY))
+#define GIMP_IS_TREE_PROXY_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_TREE_PROXY))
+#define GIMP_TREE_PROXY_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_TREE_PROXY, GimpTreeProxyClass))
+
+
+typedef struct _GimpTreeProxyPrivate GimpTreeProxyPrivate;
+typedef struct _GimpTreeProxyClass   GimpTreeProxyClass;
+
+struct _GimpTreeProxy
+{
+  GimpList              parent_instance;
+
+  GimpTreeProxyPrivate *priv;
+};
+
+struct _GimpTreeProxyClass
+{
+  GimpListClass  parent_class;
+};
+
+
+GType           gimp_tree_proxy_get_type (void) G_GNUC_CONST;
+
+GimpContainer * gimp_tree_proxy_new               (GType          children_type);
+GimpContainer * gimp_tree_proxy_new_for_container (GimpContainer *container);
+
+void            gimp_tree_proxy_set_container     (GimpTreeProxy *tree_proxy,
+                                                   GimpContainer *container);
+GimpContainer * gimp_tree_proxy_get_container     (GimpTreeProxy *tree_proxy);
+
+void            gimp_tree_proxy_set_flat          (GimpTreeProxy *tree_proxy,
+                                                   gboolean       flat);
+gboolean        gimp_tree_proxy_get_flat          (GimpTreeProxy *tree_proxy);
+
+
+#endif  /*  __GIMP_TREE_PROXY_H__  */
diff --git a/app/core/gimptriviallycancelablewaitable.c b/app/core/gimptriviallycancelablewaitable.c
new file mode 100644
index 0000000..d90a9cb
--- /dev/null
+++ b/app/core/gimptriviallycancelablewaitable.c
@@ -0,0 +1,92 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimptriviallycancelablewaitable.c
+ * Copyright (C) 2018 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gimpcancelable.h"
+#include "gimptriviallycancelablewaitable.h"
+#include "gimpwaitable.h"
+
+
+/*  local function prototypes  */
+
+static void   gimp_trivially_cancelable_waitable_cancelable_iface_init (GimpCancelableInterface *iface);
+
+static void   gimp_trivially_cancelable_waitable_cancel                (GimpCancelable          *cancelable);
+
+
+G_DEFINE_TYPE_WITH_CODE (GimpTriviallyCancelableWaitable, gimp_trivially_cancelable_waitable, GIMP_TYPE_UNCANCELABLE_WAITABLE,
+                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_CANCELABLE,
+                                                gimp_trivially_cancelable_waitable_cancelable_iface_init))
+
+#define parent_class gimp_trivially_cancelable_waitable_parent_class
+
+
+/*  private functions  */
+
+
+static void
+gimp_trivially_cancelable_waitable_class_init (GimpTriviallyCancelableWaitableClass *klass)
+{
+}
+
+static void
+gimp_trivially_cancelable_waitable_cancelable_iface_init (GimpCancelableInterface *iface)
+{
+  iface->cancel = gimp_trivially_cancelable_waitable_cancel;
+}
+
+static void
+gimp_trivially_cancelable_waitable_init (GimpTriviallyCancelableWaitable *trivially_cancelable_waitable)
+{
+}
+
+static void
+gimp_trivially_cancelable_waitable_cancel (GimpCancelable *cancelable)
+{
+  GimpUncancelableWaitable *uncancelable_waitable =
+    GIMP_UNCANCELABLE_WAITABLE (cancelable);
+
+  g_clear_object (&uncancelable_waitable->waitable);
+}
+
+
+/*  public functions  */
+
+
+GimpWaitable *
+gimp_trivially_cancelable_waitable_new (GimpWaitable *waitable)
+{
+  GimpUncancelableWaitable *uncancelable_waitable;
+
+  g_return_val_if_fail (GIMP_IS_WAITABLE (waitable), NULL);
+
+  uncancelable_waitable = g_object_new (GIMP_TYPE_TRIVIALLY_CANCELABLE_WAITABLE,
+                                        NULL);
+
+  uncancelable_waitable->waitable = g_object_ref (waitable);
+
+  return GIMP_WAITABLE (uncancelable_waitable);
+}
diff --git a/app/core/gimptriviallycancelablewaitable.h b/app/core/gimptriviallycancelablewaitable.h
new file mode 100644
index 0000000..bb09a52
--- /dev/null
+++ b/app/core/gimptriviallycancelablewaitable.h
@@ -0,0 +1,57 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimptriviallycancelablewaitable.h
+ * Copyright (C) 2018 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_TRIVIALLY_CANCELABLE_WAITABLE_H__
+#define __GIMP_TRIVIALLY_CANCELABLE_WAITABLE_H__
+
+
+#include "gimpuncancelablewaitable.h"
+
+
+#define GIMP_TYPE_TRIVIALLY_CANCELABLE_WAITABLE            (gimp_trivially_cancelable_waitable_get_type ())
+#define GIMP_TRIVIALLY_CANCELABLE_WAITABLE(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_TRIVIALLY_CANCELABLE_WAITABLE, GimpTriviallyCancelableWaitable))
+#define GIMP_TRIVIALLY_CANCELABLE_WAITABLE_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_TRIVIALLY_CANCELABLE_WAITABLE, GimpTriviallyCancelableWaitableClass))
+#define GIMP_IS_TRIVIALLY_CANCELABLE_WAITABLE(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_TRIVIALLY_CANCELABLE_WAITABLE))
+#define GIMP_IS_TRIVIALLY_CANCELABLE_WAITABLE_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_TRIVIALLY_CANCELABLE_WAITABLE))
+#define GIMP_TRIVIALLY_CANCELABLE_WAITABLE_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_TRIVIALLY_CANCELABLE_WAITABLE, GimpTriviallyCancelableWaitableClass))
+
+
+typedef struct _GimpTriviallyCancelableWaitablePrivate GimpTriviallyCancelableWaitablePrivate;
+typedef struct _GimpTriviallyCancelableWaitableClass   GimpTriviallyCancelableWaitableClass;
+
+struct _GimpTriviallyCancelableWaitable
+{
+  GimpUncancelableWaitable                parent_instance;
+
+  GimpTriviallyCancelableWaitablePrivate *priv;
+};
+
+struct _GimpTriviallyCancelableWaitableClass
+{
+  GimpUncancelableWaitableClass  parent_class;
+};
+
+
+GType          gimp_trivially_cancelable_waitable_get_type (void) G_GNUC_CONST;
+
+GimpWaitable * gimp_trivially_cancelable_waitable_new      (GimpWaitable *waitable);
+
+
+#endif /* __GIMP_TRIVIALLY_CANCELABLE_WAITABLE_H__ */
diff --git a/app/core/gimpuncancelablewaitable.c b/app/core/gimpuncancelablewaitable.c
new file mode 100644
index 0000000..596efed
--- /dev/null
+++ b/app/core/gimpuncancelablewaitable.c
@@ -0,0 +1,137 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpuncancelablewaitable.c
+ * Copyright (C) 2018 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gimpuncancelablewaitable.h"
+#include "gimpwaitable.h"
+
+
+/*  local function prototypes  */
+
+static void       gimp_uncancelable_waitable_waitable_iface_init (GimpWaitableInterface   *iface);
+
+static void       gimp_uncancelable_waitable_finalize            (GObject                 *object);
+
+static void       gimp_uncancelable_waitable_wait                (GimpWaitable            *waitable);
+static gboolean   gimp_uncancelable_waitable_try_wait            (GimpWaitable            *waitable);
+static gboolean   gimp_uncancelable_waitable_wait_until          (GimpWaitable            *waitable,
+                                                                  gint64                   end_time);
+
+
+G_DEFINE_TYPE_WITH_CODE (GimpUncancelableWaitable, gimp_uncancelable_waitable, G_TYPE_OBJECT,
+                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_WAITABLE,
+                                                gimp_uncancelable_waitable_waitable_iface_init))
+
+#define parent_class gimp_uncancelable_waitable_parent_class
+
+
+/*  private functions  */
+
+
+static void
+gimp_uncancelable_waitable_class_init (GimpUncancelableWaitableClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  object_class->finalize = gimp_uncancelable_waitable_finalize;
+}
+
+static void
+gimp_uncancelable_waitable_waitable_iface_init (GimpWaitableInterface *iface)
+{
+  iface->wait       = gimp_uncancelable_waitable_wait;
+  iface->try_wait   = gimp_uncancelable_waitable_try_wait;
+  iface->wait_until = gimp_uncancelable_waitable_wait_until;
+}
+
+static void
+gimp_uncancelable_waitable_init (GimpUncancelableWaitable *uncancelable_waitable)
+{
+}
+
+static void
+gimp_uncancelable_waitable_finalize (GObject *object)
+{
+  GimpUncancelableWaitable *uncancelable_waitable =
+    GIMP_UNCANCELABLE_WAITABLE (object);
+
+  g_clear_object (&uncancelable_waitable->waitable);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gimp_uncancelable_waitable_wait (GimpWaitable *waitable)
+{
+  GimpUncancelableWaitable *uncancelable_waitable =
+    GIMP_UNCANCELABLE_WAITABLE (waitable);
+
+  if (uncancelable_waitable->waitable)
+    gimp_waitable_wait (uncancelable_waitable->waitable);
+}
+
+static gboolean
+gimp_uncancelable_waitable_try_wait (GimpWaitable *waitable)
+{
+  GimpUncancelableWaitable *uncancelable_waitable =
+    GIMP_UNCANCELABLE_WAITABLE (waitable);
+
+  if (uncancelable_waitable->waitable)
+    return gimp_waitable_try_wait (uncancelable_waitable->waitable);
+  else
+    return TRUE;
+}
+
+static gboolean
+gimp_uncancelable_waitable_wait_until (GimpWaitable *waitable,
+                                gint64        end_time)
+{
+  GimpUncancelableWaitable *uncancelable_waitable =
+    GIMP_UNCANCELABLE_WAITABLE (waitable);
+
+  if (uncancelable_waitable->waitable)
+    return gimp_waitable_wait_until (uncancelable_waitable->waitable, end_time);
+  else
+    return TRUE;
+}
+
+
+/*  public functions  */
+
+
+GimpWaitable *
+gimp_uncancelable_waitable_new (GimpWaitable *waitable)
+{
+  GimpUncancelableWaitable *uncancelable_waitable;
+
+  g_return_val_if_fail (GIMP_IS_WAITABLE (waitable), NULL);
+
+  uncancelable_waitable = g_object_new (GIMP_TYPE_UNCANCELABLE_WAITABLE, NULL);
+
+  uncancelable_waitable->waitable = g_object_ref (waitable);
+
+  return GIMP_WAITABLE (uncancelable_waitable);
+}
diff --git a/app/core/gimpuncancelablewaitable.h b/app/core/gimpuncancelablewaitable.h
new file mode 100644
index 0000000..90b26ff
--- /dev/null
+++ b/app/core/gimpuncancelablewaitable.h
@@ -0,0 +1,54 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpuncancelablewaitable.h
+ * Copyright (C) 2018 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_UNCANCELABLE_WAITABLE_H__
+#define __GIMP_UNCANCELABLE_WAITABLE_H__
+
+
+#define GIMP_TYPE_UNCANCELABLE_WAITABLE            (gimp_uncancelable_waitable_get_type ())
+#define GIMP_UNCANCELABLE_WAITABLE(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_UNCANCELABLE_WAITABLE, GimpUncancelableWaitable))
+#define GIMP_UNCANCELABLE_WAITABLE_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_UNCANCELABLE_WAITABLE, GimpUncancelableWaitableClass))
+#define GIMP_IS_UNCANCELABLE_WAITABLE(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_UNCANCELABLE_WAITABLE))
+#define GIMP_IS_UNCANCELABLE_WAITABLE_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_UNCANCELABLE_WAITABLE))
+#define GIMP_UNCANCELABLE_WAITABLE_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_UNCANCELABLE_WAITABLE, GimpUncancelableWaitableClass))
+
+
+typedef struct _GimpUncancelableWaitablePrivate GimpUncancelableWaitablePrivate;
+typedef struct _GimpUncancelableWaitableClass   GimpUncancelableWaitableClass;
+
+struct _GimpUncancelableWaitable
+{
+  GObject       parent_instance;
+
+  GimpWaitable *waitable;
+};
+
+struct _GimpUncancelableWaitableClass
+{
+  GObjectClass  parent_class;
+};
+
+
+GType          gimp_uncancelable_waitable_get_type (void) G_GNUC_CONST;
+
+GimpWaitable * gimp_uncancelable_waitable_new      (GimpWaitable *waitable);
+
+
+#endif /* __GIMP_UNCANCELABLE_WAITABLE_H__ */
diff --git a/app/core/gimpundo.c b/app/core/gimpundo.c
new file mode 100644
index 0000000..68bbae0
--- /dev/null
+++ b/app/core/gimpundo.c
@@ -0,0 +1,585 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <time.h>
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpbase/gimpbase.h"
+
+#include "core-types.h"
+
+#include "config/gimpcoreconfig.h"
+
+#include "gimp.h"
+#include "gimpcontext.h"
+#include "gimpimage.h"
+#include "gimpimage-undo.h"
+#include "gimpmarshal.h"
+#include "gimptempbuf.h"
+#include "gimpundo.h"
+#include "gimpundostack.h"
+
+#include "gimp-priorities.h"
+
+#include "gimp-intl.h"
+
+
+enum
+{
+  POP,
+  FREE,
+  LAST_SIGNAL
+};
+
+enum
+{
+  PROP_0,
+  PROP_IMAGE,
+  PROP_TIME,
+  PROP_UNDO_TYPE,
+  PROP_DIRTY_MASK
+};
+
+
+static void          gimp_undo_constructed         (GObject             *object);
+static void          gimp_undo_finalize            (GObject             *object);
+static void          gimp_undo_set_property        (GObject             *object,
+                                                    guint                property_id,
+                                                    const GValue        *value,
+                                                    GParamSpec          *pspec);
+static void          gimp_undo_get_property        (GObject             *object,
+                                                    guint                property_id,
+                                                    GValue              *value,
+                                                    GParamSpec          *pspec);
+
+static gint64        gimp_undo_get_memsize         (GimpObject          *object,
+                                                    gint64              *gui_size);
+
+static gboolean      gimp_undo_get_popup_size      (GimpViewable        *viewable,
+                                                    gint                 width,
+                                                    gint                 height,
+                                                    gboolean             dot_for_dot,
+                                                    gint                *popup_width,
+                                                    gint                *popup_height);
+static GimpTempBuf * gimp_undo_get_new_preview     (GimpViewable        *viewable,
+                                                    GimpContext         *context,
+                                                    gint                 width,
+                                                    gint                 height);
+
+static void          gimp_undo_real_pop            (GimpUndo            *undo,
+                                                    GimpUndoMode         undo_mode,
+                                                    GimpUndoAccumulator *accum);
+static void          gimp_undo_real_free           (GimpUndo            *undo,
+                                                    GimpUndoMode         undo_mode);
+
+static gboolean      gimp_undo_create_preview_idle (gpointer             data);
+static void       gimp_undo_create_preview_private (GimpUndo            *undo,
+                                                    GimpContext         *context);
+
+
+G_DEFINE_TYPE (GimpUndo, gimp_undo, GIMP_TYPE_VIEWABLE)
+
+#define parent_class gimp_undo_parent_class
+
+static guint undo_signals[LAST_SIGNAL] = { 0 };
+
+
+static void
+gimp_undo_class_init (GimpUndoClass *klass)
+{
+  GObjectClass      *object_class      = G_OBJECT_CLASS (klass);
+  GimpObjectClass   *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+  GimpViewableClass *viewable_class    = GIMP_VIEWABLE_CLASS (klass);
+
+  undo_signals[POP] =
+    g_signal_new ("pop",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpUndoClass, pop),
+                  NULL, NULL,
+                  gimp_marshal_VOID__ENUM_POINTER,
+                  G_TYPE_NONE, 2,
+                  GIMP_TYPE_UNDO_MODE,
+                  G_TYPE_POINTER);
+
+  undo_signals[FREE] =
+    g_signal_new ("free",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpUndoClass, free),
+                  NULL, NULL,
+                  gimp_marshal_VOID__ENUM,
+                  G_TYPE_NONE, 1,
+                  GIMP_TYPE_UNDO_MODE);
+
+  object_class->constructed         = gimp_undo_constructed;
+  object_class->finalize            = gimp_undo_finalize;
+  object_class->set_property        = gimp_undo_set_property;
+  object_class->get_property        = gimp_undo_get_property;
+
+  gimp_object_class->get_memsize    = gimp_undo_get_memsize;
+
+  viewable_class->default_icon_name = "edit-undo";
+  viewable_class->get_popup_size    = gimp_undo_get_popup_size;
+  viewable_class->get_new_preview   = gimp_undo_get_new_preview;
+
+  klass->pop                        = gimp_undo_real_pop;
+  klass->free                       = gimp_undo_real_free;
+
+  g_object_class_install_property (object_class, PROP_IMAGE,
+                                   g_param_spec_object ("image", NULL, NULL,
+                                                        GIMP_TYPE_IMAGE,
+                                                        GIMP_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT_ONLY));
+
+  g_object_class_install_property (object_class, PROP_TIME,
+                                   g_param_spec_uint ("time", NULL, NULL,
+                                                      0, G_MAXUINT, 0,
+                                                      GIMP_PARAM_READWRITE));
+
+  g_object_class_install_property (object_class, PROP_UNDO_TYPE,
+                                   g_param_spec_enum ("undo-type", NULL, NULL,
+                                                      GIMP_TYPE_UNDO_TYPE,
+                                                      GIMP_UNDO_GROUP_NONE,
+                                                      GIMP_PARAM_READWRITE |
+                                                      G_PARAM_CONSTRUCT_ONLY));
+
+  g_object_class_install_property (object_class, PROP_DIRTY_MASK,
+                                   g_param_spec_flags ("dirty-mask",
+                                                       NULL, NULL,
+                                                       GIMP_TYPE_DIRTY_MASK,
+                                                       GIMP_DIRTY_NONE,
+                                                       GIMP_PARAM_READWRITE |
+                                                       G_PARAM_CONSTRUCT_ONLY));
+}
+
+static void
+gimp_undo_init (GimpUndo *undo)
+{
+  undo->time = time (NULL);
+}
+
+static void
+gimp_undo_constructed (GObject *object)
+{
+  GimpUndo *undo = GIMP_UNDO (object);
+
+  G_OBJECT_CLASS (parent_class)->constructed (object);
+
+  gimp_assert (GIMP_IS_IMAGE (undo->image));
+}
+
+static void
+gimp_undo_finalize (GObject *object)
+{
+  GimpUndo *undo = GIMP_UNDO (object);
+
+  if (undo->preview_idle_id)
+    {
+      g_source_remove (undo->preview_idle_id);
+      undo->preview_idle_id = 0;
+    }
+
+  g_clear_pointer (&undo->preview, gimp_temp_buf_unref);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gimp_undo_set_property (GObject      *object,
+                        guint         property_id,
+                        const GValue *value,
+                        GParamSpec   *pspec)
+{
+  GimpUndo *undo = GIMP_UNDO (object);
+
+  switch (property_id)
+    {
+    case PROP_IMAGE:
+      /* don't ref */
+      undo->image = g_value_get_object (value);
+      break;
+    case PROP_TIME:
+      undo->time = g_value_get_uint (value);
+      break;
+    case PROP_UNDO_TYPE:
+      undo->undo_type = g_value_get_enum (value);
+      break;
+    case PROP_DIRTY_MASK:
+      undo->dirty_mask = g_value_get_flags (value);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_undo_get_property (GObject    *object,
+                        guint       property_id,
+                        GValue     *value,
+                        GParamSpec *pspec)
+{
+  GimpUndo *undo = GIMP_UNDO (object);
+
+  switch (property_id)
+    {
+    case PROP_IMAGE:
+      g_value_set_object (value, undo->image);
+      break;
+    case PROP_TIME:
+      g_value_set_uint (value, undo->time);
+      break;
+    case PROP_UNDO_TYPE:
+      g_value_set_enum (value, undo->undo_type);
+      break;
+    case PROP_DIRTY_MASK:
+      g_value_set_flags (value, undo->dirty_mask);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static gint64
+gimp_undo_get_memsize (GimpObject *object,
+                       gint64     *gui_size)
+{
+  GimpUndo *undo    = GIMP_UNDO (object);
+  gint64    memsize = 0;
+
+  *gui_size += gimp_temp_buf_get_memsize (undo->preview);
+
+  return memsize + GIMP_OBJECT_CLASS (parent_class)->get_memsize (object,
+                                                                  gui_size);
+}
+
+static gboolean
+gimp_undo_get_popup_size (GimpViewable *viewable,
+                          gint          width,
+                          gint          height,
+                          gboolean      dot_for_dot,
+                          gint         *popup_width,
+                          gint         *popup_height)
+{
+  GimpUndo *undo = GIMP_UNDO (viewable);
+
+  if (undo->preview &&
+      (gimp_temp_buf_get_width  (undo->preview) > width ||
+       gimp_temp_buf_get_height (undo->preview) > height))
+    {
+      *popup_width  = gimp_temp_buf_get_width  (undo->preview);
+      *popup_height = gimp_temp_buf_get_height (undo->preview);
+
+      return TRUE;
+    }
+
+  return FALSE;
+}
+
+static GimpTempBuf *
+gimp_undo_get_new_preview (GimpViewable *viewable,
+                           GimpContext  *context,
+                           gint          width,
+                           gint          height)
+{
+  GimpUndo *undo = GIMP_UNDO (viewable);
+
+  if (undo->preview)
+    {
+      gint preview_width;
+      gint preview_height;
+
+      gimp_viewable_calc_preview_size (gimp_temp_buf_get_width  (undo->preview),
+                                       gimp_temp_buf_get_height (undo->preview),
+                                       width,
+                                       height,
+                                       TRUE, 1.0, 1.0,
+                                       &preview_width,
+                                       &preview_height,
+                                       NULL);
+
+      if (preview_width  < gimp_temp_buf_get_width  (undo->preview) &&
+          preview_height < gimp_temp_buf_get_height (undo->preview))
+        {
+          return gimp_temp_buf_scale (undo->preview,
+                                      preview_width, preview_height);
+        }
+
+      return gimp_temp_buf_copy (undo->preview);
+    }
+
+  return NULL;
+}
+
+static void
+gimp_undo_real_pop (GimpUndo            *undo,
+                    GimpUndoMode         undo_mode,
+                    GimpUndoAccumulator *accum)
+{
+}
+
+static void
+gimp_undo_real_free (GimpUndo     *undo,
+                     GimpUndoMode  undo_mode)
+{
+}
+
+void
+gimp_undo_pop (GimpUndo            *undo,
+               GimpUndoMode         undo_mode,
+               GimpUndoAccumulator *accum)
+{
+  g_return_if_fail (GIMP_IS_UNDO (undo));
+  g_return_if_fail (accum != NULL);
+
+  if (undo->dirty_mask != GIMP_DIRTY_NONE)
+    {
+      switch (undo_mode)
+        {
+        case GIMP_UNDO_MODE_UNDO:
+          gimp_image_clean (undo->image, undo->dirty_mask);
+          break;
+
+        case GIMP_UNDO_MODE_REDO:
+          gimp_image_dirty (undo->image, undo->dirty_mask);
+          break;
+        }
+    }
+
+  g_signal_emit (undo, undo_signals[POP], 0, undo_mode, accum);
+}
+
+void
+gimp_undo_free (GimpUndo     *undo,
+                GimpUndoMode  undo_mode)
+{
+  g_return_if_fail (GIMP_IS_UNDO (undo));
+
+  g_signal_emit (undo, undo_signals[FREE], 0, undo_mode);
+}
+
+typedef struct _GimpUndoIdle GimpUndoIdle;
+
+struct _GimpUndoIdle
+{
+  GimpUndo    *undo;
+  GimpContext *context;
+};
+
+static void
+gimp_undo_idle_free (GimpUndoIdle *idle)
+{
+  if (idle->context)
+    g_object_unref (idle->context);
+
+  g_slice_free (GimpUndoIdle, idle);
+}
+
+void
+gimp_undo_create_preview (GimpUndo    *undo,
+                          GimpContext *context,
+                          gboolean     create_now)
+{
+  g_return_if_fail (GIMP_IS_UNDO (undo));
+  g_return_if_fail (context == NULL || GIMP_IS_CONTEXT (context));
+
+  if (undo->preview || undo->preview_idle_id)
+    return;
+
+  if (create_now)
+    {
+      gimp_undo_create_preview_private (undo, context);
+    }
+  else
+    {
+      GimpUndoIdle *idle = g_slice_new0 (GimpUndoIdle);
+
+      idle->undo = undo;
+
+      if (context)
+        idle->context = g_object_ref (context);
+
+      undo->preview_idle_id =
+        g_idle_add_full (GIMP_PRIORITY_VIEWABLE_IDLE,
+                         gimp_undo_create_preview_idle, idle,
+                         (GDestroyNotify) gimp_undo_idle_free);
+    }
+}
+
+static gboolean
+gimp_undo_create_preview_idle (gpointer data)
+{
+  GimpUndoIdle *idle   = data;
+  GimpUndoStack *stack = gimp_image_get_undo_stack (idle->undo->image);
+
+  if (idle->undo == gimp_undo_stack_peek (stack))
+    {
+      gimp_undo_create_preview_private (idle->undo, idle->context);
+    }
+
+  idle->undo->preview_idle_id = 0;
+
+  return FALSE;
+}
+
+static void
+gimp_undo_create_preview_private (GimpUndo    *undo,
+                                  GimpContext *context)
+{
+  GimpImage    *image = undo->image;
+  GimpViewable *preview_viewable;
+  GimpViewSize  preview_size;
+  gint          width;
+  gint          height;
+
+  switch (undo->undo_type)
+    {
+    case GIMP_UNDO_GROUP_IMAGE_QUICK_MASK:
+    case GIMP_UNDO_GROUP_MASK:
+    case GIMP_UNDO_MASK:
+      preview_viewable = GIMP_VIEWABLE (gimp_image_get_mask (image));
+      break;
+
+    default:
+      preview_viewable = GIMP_VIEWABLE (image);
+      break;
+    }
+
+  preview_size = image->gimp->config->undo_preview_size;
+
+  if (gimp_image_get_width  (image) <= preview_size &&
+      gimp_image_get_height (image) <= preview_size)
+    {
+      width  = gimp_image_get_width  (image);
+      height = gimp_image_get_height (image);
+    }
+  else
+    {
+      if (gimp_image_get_width (image) > gimp_image_get_height (image))
+        {
+          width  = preview_size;
+          height = MAX (1, (gimp_image_get_height (image) * preview_size /
+                            gimp_image_get_width (image)));
+        }
+      else
+        {
+          height = preview_size;
+          width  = MAX (1, (gimp_image_get_width (image) * preview_size /
+                            gimp_image_get_height (image)));
+        }
+    }
+
+  undo->preview = gimp_viewable_get_new_preview (preview_viewable, context,
+                                                 width, height);
+
+  gimp_viewable_invalidate_preview (GIMP_VIEWABLE (undo));
+}
+
+void
+gimp_undo_refresh_preview (GimpUndo    *undo,
+                           GimpContext *context)
+{
+  g_return_if_fail (GIMP_IS_UNDO (undo));
+  g_return_if_fail (context == NULL || GIMP_IS_CONTEXT (context));
+
+  if (undo->preview_idle_id)
+    return;
+
+  if (undo->preview)
+    {
+      g_clear_pointer (&undo->preview, gimp_temp_buf_unref);
+      gimp_undo_create_preview (undo, context, FALSE);
+    }
+}
+
+const gchar *
+gimp_undo_type_to_name (GimpUndoType type)
+{
+  const gchar *desc;
+
+  if (gimp_enum_get_value (GIMP_TYPE_UNDO_TYPE, type, NULL, NULL, &desc, NULL))
+    return desc;
+  else
+    return "";
+}
+
+gboolean
+gimp_undo_is_weak (GimpUndo *undo)
+{
+  if (! undo)
+    return FALSE;
+
+  switch (undo->undo_type)
+    {
+    case GIMP_UNDO_GROUP_ITEM_VISIBILITY:
+    case GIMP_UNDO_GROUP_ITEM_PROPERTIES:
+    case GIMP_UNDO_GROUP_LAYER_APPLY_MASK:
+    case GIMP_UNDO_ITEM_VISIBILITY:
+    case GIMP_UNDO_LAYER_MODE:
+    case GIMP_UNDO_LAYER_OPACITY:
+    case GIMP_UNDO_LAYER_MASK_APPLY:
+    case GIMP_UNDO_LAYER_MASK_SHOW:
+      return TRUE;
+      break;
+
+    default:
+      break;
+    }
+
+  return FALSE;
+}
+
+/**
+ * gimp_undo_get_age:
+ * @undo:
+ *
+ * Return value: the time in seconds since this undo item was created
+ */
+gint
+gimp_undo_get_age (GimpUndo *undo)
+{
+  guint now = time (NULL);
+
+  g_return_val_if_fail (GIMP_IS_UNDO (undo), 0);
+  g_return_val_if_fail (now >= undo->time, 0);
+
+  return now - undo->time;
+}
+
+/**
+ * gimp_undo_reset_age:
+ * @undo:
+ *
+ * Changes the creation time of this undo item to the current time.
+ */
+void
+gimp_undo_reset_age (GimpUndo *undo)
+{
+  g_return_if_fail (GIMP_IS_UNDO (undo));
+
+  undo->time = time (NULL);
+
+  g_object_notify (G_OBJECT (undo), "time");
+}
diff --git a/app/core/gimpundo.h b/app/core/gimpundo.h
new file mode 100644
index 0000000..03d03c2
--- /dev/null
+++ b/app/core/gimpundo.h
@@ -0,0 +1,99 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_UNDO_H__
+#define __GIMP_UNDO_H__
+
+
+#include "gimpviewable.h"
+
+
+struct _GimpUndoAccumulator
+{
+  gboolean mode_changed;
+  gboolean precision_changed;
+
+  gboolean size_changed;
+  gint     previous_origin_x;
+  gint     previous_origin_y;
+  gint     previous_width;
+  gint     previous_height;
+
+  gboolean resolution_changed;
+
+  gboolean unit_changed;
+};
+
+
+#define GIMP_TYPE_UNDO            (gimp_undo_get_type ())
+#define GIMP_UNDO(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_UNDO, GimpUndo))
+#define GIMP_UNDO_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_UNDO, GimpUndoClass))
+#define GIMP_IS_UNDO(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_UNDO))
+#define GIMP_IS_UNDO_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_UNDO))
+#define GIMP_UNDO_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_UNDO, GimpUndoClass))
+
+
+typedef struct _GimpUndoClass GimpUndoClass;
+
+struct _GimpUndo
+{
+  GimpViewable      parent_instance;
+
+  GimpImage        *image;          /* the image this undo is part of     */
+  guint             time;           /* time of undo step construction     */
+
+  GimpUndoType      undo_type;      /* undo type                          */
+  GimpDirtyMask     dirty_mask;     /* affected parts of the image        */
+
+  GimpTempBuf      *preview;
+  guint             preview_idle_id;
+};
+
+struct _GimpUndoClass
+{
+  GimpViewableClass  parent_class;
+
+  void (* pop)  (GimpUndo            *undo,
+                 GimpUndoMode         undo_mode,
+                 GimpUndoAccumulator *accum);
+  void (* free) (GimpUndo            *undo,
+                 GimpUndoMode         undo_mode);
+};
+
+
+GType         gimp_undo_get_type        (void) G_GNUC_CONST;
+
+void          gimp_undo_pop             (GimpUndo            *undo,
+                                         GimpUndoMode         undo_mode,
+                                         GimpUndoAccumulator *accum);
+void          gimp_undo_free            (GimpUndo            *undo,
+                                         GimpUndoMode         undo_mode);
+
+void          gimp_undo_create_preview  (GimpUndo            *undo,
+                                         GimpContext         *context,
+                                         gboolean             create_now);
+void          gimp_undo_refresh_preview (GimpUndo            *undo,
+                                         GimpContext         *context);
+
+const gchar * gimp_undo_type_to_name    (GimpUndoType         type);
+
+gboolean      gimp_undo_is_weak         (GimpUndo            *undo);
+gint          gimp_undo_get_age         (GimpUndo            *undo);
+void          gimp_undo_reset_age       (GimpUndo            *undo);
+
+
+#endif /* __GIMP_UNDO_H__ */
diff --git a/app/core/gimpundostack.c b/app/core/gimpundostack.c
new file mode 100644
index 0000000..666ed9b
--- /dev/null
+++ b/app/core/gimpundostack.c
@@ -0,0 +1,208 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gimpimage.h"
+#include "gimplist.h"
+#include "gimpundo.h"
+#include "gimpundostack.h"
+
+
+static void    gimp_undo_stack_finalize    (GObject             *object);
+
+static gint64  gimp_undo_stack_get_memsize (GimpObject          *object,
+                                            gint64              *gui_size);
+
+static void    gimp_undo_stack_pop         (GimpUndo            *undo,
+                                            GimpUndoMode         undo_mode,
+                                            GimpUndoAccumulator *accum);
+static void    gimp_undo_stack_free        (GimpUndo            *undo,
+                                            GimpUndoMode         undo_mode);
+
+
+G_DEFINE_TYPE (GimpUndoStack, gimp_undo_stack, GIMP_TYPE_UNDO)
+
+#define parent_class gimp_undo_stack_parent_class
+
+
+static void
+gimp_undo_stack_class_init (GimpUndoStackClass *klass)
+{
+  GObjectClass    *object_class      = G_OBJECT_CLASS (klass);
+  GimpObjectClass *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+  GimpUndoClass   *undo_class        = GIMP_UNDO_CLASS (klass);
+
+  object_class->finalize         = gimp_undo_stack_finalize;
+
+  gimp_object_class->get_memsize = gimp_undo_stack_get_memsize;
+
+  undo_class->pop                = gimp_undo_stack_pop;
+  undo_class->free               = gimp_undo_stack_free;
+}
+
+static void
+gimp_undo_stack_init (GimpUndoStack *stack)
+{
+  stack->undos = gimp_list_new (GIMP_TYPE_UNDO, FALSE);
+}
+
+static void
+gimp_undo_stack_finalize (GObject *object)
+{
+  GimpUndoStack *stack = GIMP_UNDO_STACK (object);
+
+  g_clear_object (&stack->undos);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static gint64
+gimp_undo_stack_get_memsize (GimpObject *object,
+                             gint64     *gui_size)
+{
+  GimpUndoStack *stack   = GIMP_UNDO_STACK (object);
+  gint64         memsize = 0;
+
+  memsize += gimp_object_get_memsize (GIMP_OBJECT (stack->undos), gui_size);
+
+  return memsize + GIMP_OBJECT_CLASS (parent_class)->get_memsize (object,
+                                                                  gui_size);
+}
+
+static void
+gimp_undo_stack_pop (GimpUndo            *undo,
+                     GimpUndoMode         undo_mode,
+                     GimpUndoAccumulator *accum)
+{
+  GimpUndoStack *stack = GIMP_UNDO_STACK (undo);
+  GList         *list;
+
+  for (list = GIMP_LIST (stack->undos)->queue->head;
+       list;
+       list = g_list_next (list))
+    {
+      GimpUndo *child = list->data;
+
+      gimp_undo_pop (child, undo_mode, accum);
+    }
+}
+
+static void
+gimp_undo_stack_free (GimpUndo     *undo,
+                      GimpUndoMode  undo_mode)
+{
+  GimpUndoStack *stack = GIMP_UNDO_STACK (undo);
+  GList         *list;
+
+  for (list = GIMP_LIST (stack->undos)->queue->head;
+       list;
+       list = g_list_next (list))
+    {
+      GimpUndo *child = list->data;
+
+      gimp_undo_free (child, undo_mode);
+      g_object_unref (child);
+    }
+
+  gimp_container_clear (stack->undos);
+}
+
+GimpUndoStack *
+gimp_undo_stack_new (GimpImage *image)
+{
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
+
+  return g_object_new (GIMP_TYPE_UNDO_STACK,
+                       "image", image,
+                       NULL);
+}
+
+void
+gimp_undo_stack_push_undo (GimpUndoStack *stack,
+                           GimpUndo      *undo)
+{
+  g_return_if_fail (GIMP_IS_UNDO_STACK (stack));
+  g_return_if_fail (GIMP_IS_UNDO (undo));
+
+  gimp_container_add (stack->undos, GIMP_OBJECT (undo));
+}
+
+GimpUndo *
+gimp_undo_stack_pop_undo (GimpUndoStack       *stack,
+                          GimpUndoMode         undo_mode,
+                          GimpUndoAccumulator *accum)
+{
+  GimpUndo *undo;
+
+  g_return_val_if_fail (GIMP_IS_UNDO_STACK (stack), NULL);
+  g_return_val_if_fail (accum != NULL, NULL);
+
+  undo = GIMP_UNDO (gimp_container_get_first_child (stack->undos));
+
+  if (undo)
+    {
+      gimp_container_remove (stack->undos, GIMP_OBJECT (undo));
+      gimp_undo_pop (undo, undo_mode, accum);
+
+      return undo;
+    }
+
+  return NULL;
+}
+
+GimpUndo *
+gimp_undo_stack_free_bottom (GimpUndoStack *stack,
+                             GimpUndoMode   undo_mode)
+{
+  GimpUndo *undo;
+
+  g_return_val_if_fail (GIMP_IS_UNDO_STACK (stack), NULL);
+
+  undo = GIMP_UNDO (gimp_container_get_last_child (stack->undos));
+
+  if (undo)
+    {
+      gimp_container_remove (stack->undos, GIMP_OBJECT (undo));
+      gimp_undo_free (undo, undo_mode);
+
+      return undo;
+    }
+
+  return NULL;
+}
+
+GimpUndo *
+gimp_undo_stack_peek (GimpUndoStack *stack)
+{
+  g_return_val_if_fail (GIMP_IS_UNDO_STACK (stack), NULL);
+
+  return GIMP_UNDO (gimp_container_get_first_child (stack->undos));
+}
+
+gint
+gimp_undo_stack_get_depth (GimpUndoStack *stack)
+{
+  g_return_val_if_fail (GIMP_IS_UNDO_STACK (stack), 0);
+
+  return gimp_container_get_n_children (stack->undos);
+}
diff --git a/app/core/gimpundostack.h b/app/core/gimpundostack.h
new file mode 100644
index 0000000..8432df0
--- /dev/null
+++ b/app/core/gimpundostack.h
@@ -0,0 +1,64 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_UNDO_STACK_H__
+#define __GIMP_UNDO_STACK_H__
+
+
+#include "gimpundo.h"
+
+
+#define GIMP_TYPE_UNDO_STACK            (gimp_undo_stack_get_type ())
+#define GIMP_UNDO_STACK(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_UNDO_STACK, GimpUndoStack))
+#define GIMP_UNDO_STACK_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_UNDO_STACK, GimpUndoStackClass))
+#define GIMP_IS_UNDO_STACK(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_UNDO_STACK))
+#define GIMP_IS_UNDO_STACK_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_UNDO_STACK))
+#define GIMP_UNDO_STACK_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_UNDO_STACK, GimpUndoStackClass))
+
+
+typedef struct _GimpUndoStackClass GimpUndoStackClass;
+
+struct _GimpUndoStack
+{
+  GimpUndo       parent_instance;
+
+  GimpContainer *undos;
+};
+
+struct _GimpUndoStackClass
+{
+  GimpUndoClass  parent_class;
+};
+
+
+GType           gimp_undo_stack_get_type    (void) G_GNUC_CONST;
+
+GimpUndoStack * gimp_undo_stack_new         (GimpImage           *image);
+
+void            gimp_undo_stack_push_undo   (GimpUndoStack       *stack,
+                                             GimpUndo            *undo);
+GimpUndo      * gimp_undo_stack_pop_undo    (GimpUndoStack       *stack,
+                                             GimpUndoMode         undo_mode,
+                                             GimpUndoAccumulator *accum);
+
+GimpUndo      * gimp_undo_stack_free_bottom (GimpUndoStack       *stack,
+                                             GimpUndoMode         undo_mode);
+GimpUndo      * gimp_undo_stack_peek        (GimpUndoStack       *stack);
+gint            gimp_undo_stack_get_depth   (GimpUndoStack       *stack);
+
+
+#endif /* __GIMP_UNDO_STACK_H__ */
diff --git a/app/core/gimpunit.c b/app/core/gimpunit.c
new file mode 100644
index 0000000..3fad305
--- /dev/null
+++ b/app/core/gimpunit.c
@@ -0,0 +1,305 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1999 Spencer Kimball and Peter Mattis
+ *
+ * gimpunit.c
+ * Copyright (C) 1999-2000 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/* This file contains the definition of the size unit objects. The
+ * factor of the units is relative to inches (which have a factor of 1).
+ */
+
+#include "config.h"
+
+#include <gio/gio.h>
+
+#include "libgimpbase/gimpbase.h"
+
+#include "core-types.h"
+
+#include "gimp.h"
+#include "gimpunit.h"
+
+#include "gimp-intl.h"
+
+
+/* internal structures */
+
+typedef struct
+{
+  gboolean  delete_on_exit;
+  gdouble   factor;
+  gint      digits;
+  gchar    *identifier;
+  gchar    *symbol;
+  gchar    *abbreviation;
+  gchar    *singular;
+  gchar    *plural;
+} GimpUnitDef;
+
+
+/*  these are the built-in units
+ */
+static const GimpUnitDef gimp_unit_defs[GIMP_UNIT_END] =
+{
+  /* pseudo unit */
+  { FALSE,  0.0, 0, "pixels",      "px", "px",
+    NC_("unit-singular", "pixel"),      NC_("unit-plural", "pixels")      },
+
+  /* standard units */
+  { FALSE,  1.0, 2, "inches",      "''", "in",
+    NC_("unit-singular", "inch"),       NC_("unit-plural", "inches")      },
+
+  { FALSE, 25.4, 1, "millimeters", "mm", "mm",
+    NC_("unit-singular", "millimeter"), NC_("unit-plural", "millimeters") },
+
+  /* professional units */
+  { FALSE, 72.0, 0, "points",      "pt", "pt",
+    NC_("unit-singular", "point"),      NC_("unit-plural", "points")      },
+
+  { FALSE,  6.0, 1, "picas",       "pc", "pc",
+    NC_("unit-singular", "pica"),       NC_("unit-plural", "picas")       }
+};
+
+/*  not a unit at all but kept here to have the strings in one place
+ */
+static const GimpUnitDef gimp_unit_percent =
+{
+    FALSE,  0.0, 0, "percent",     "%",  "%",
+    NC_("singular", "percent"),    NC_("plural", "percent")
+};
+
+
+/* private functions */
+
+static GimpUnitDef *
+_gimp_unit_get_user_unit (Gimp     *gimp,
+                          GimpUnit  unit)
+{
+  return g_list_nth_data (gimp->user_units, unit - GIMP_UNIT_END);
+}
+
+
+/* public functions */
+
+gint
+_gimp_unit_get_number_of_units (Gimp *gimp)
+{
+  return GIMP_UNIT_END + gimp->n_user_units;
+}
+
+gint
+_gimp_unit_get_number_of_built_in_units (Gimp *gimp)
+{
+  return GIMP_UNIT_END;
+}
+
+GimpUnit
+_gimp_unit_new (Gimp        *gimp,
+                const gchar *identifier,
+                gdouble      factor,
+                gint         digits,
+                const gchar *symbol,
+                const gchar *abbreviation,
+                const gchar *singular,
+                const gchar *plural)
+{
+  GimpUnitDef *user_unit = g_slice_new0 (GimpUnitDef);
+
+  user_unit->delete_on_exit = TRUE;
+  user_unit->factor         = factor;
+  user_unit->digits         = digits;
+  user_unit->identifier     = g_strdup (identifier);
+  user_unit->symbol         = g_strdup (symbol);
+  user_unit->abbreviation   = g_strdup (abbreviation);
+  user_unit->singular       = g_strdup (singular);
+  user_unit->plural         = g_strdup (plural);
+
+  gimp->user_units = g_list_append (gimp->user_units, user_unit);
+  gimp->n_user_units++;
+
+  return GIMP_UNIT_END + gimp->n_user_units - 1;
+}
+
+gboolean
+_gimp_unit_get_deletion_flag (Gimp     *gimp,
+                              GimpUnit  unit)
+{
+  g_return_val_if_fail (unit < (GIMP_UNIT_END + gimp->n_user_units), FALSE);
+
+  if (unit < GIMP_UNIT_END)
+    return FALSE;
+
+  return _gimp_unit_get_user_unit (gimp, unit)->delete_on_exit;
+}
+
+void
+_gimp_unit_set_deletion_flag (Gimp     *gimp,
+                              GimpUnit  unit,
+                              gboolean  deletion_flag)
+{
+  g_return_if_fail ((unit >= GIMP_UNIT_END) &&
+                    (unit < (GIMP_UNIT_END + gimp->n_user_units)));
+
+  _gimp_unit_get_user_unit (gimp, unit)->delete_on_exit =
+    deletion_flag ? TRUE : FALSE;
+}
+
+gdouble
+_gimp_unit_get_factor (Gimp     *gimp,
+                       GimpUnit  unit)
+{
+  g_return_val_if_fail (unit < (GIMP_UNIT_END + gimp->n_user_units) ||
+                        (unit == GIMP_UNIT_PERCENT),
+                        gimp_unit_defs[GIMP_UNIT_INCH].factor);
+
+  if (unit < GIMP_UNIT_END)
+    return gimp_unit_defs[unit].factor;
+
+  if (unit == GIMP_UNIT_PERCENT)
+    return gimp_unit_percent.factor;
+
+  return _gimp_unit_get_user_unit (gimp, unit)->factor;
+}
+
+gint
+_gimp_unit_get_digits (Gimp     *gimp,
+                       GimpUnit  unit)
+{
+  g_return_val_if_fail (unit < (GIMP_UNIT_END + gimp->n_user_units) ||
+                        (unit == GIMP_UNIT_PERCENT),
+                        gimp_unit_defs[GIMP_UNIT_INCH].digits);
+
+  if (unit < GIMP_UNIT_END)
+    return gimp_unit_defs[unit].digits;
+
+  if (unit == GIMP_UNIT_PERCENT)
+    return gimp_unit_percent.digits;
+
+  return _gimp_unit_get_user_unit (gimp, unit)->digits;
+}
+
+const gchar *
+_gimp_unit_get_identifier (Gimp     *gimp,
+                           GimpUnit  unit)
+{
+  g_return_val_if_fail ((unit < (GIMP_UNIT_END + gimp->n_user_units)) ||
+                        (unit == GIMP_UNIT_PERCENT),
+                        gimp_unit_defs[GIMP_UNIT_INCH].identifier);
+
+  if (unit < GIMP_UNIT_END)
+    return gimp_unit_defs[unit].identifier;
+
+  if (unit == GIMP_UNIT_PERCENT)
+    return gimp_unit_percent.identifier;
+
+  return _gimp_unit_get_user_unit (gimp, unit)->identifier;
+}
+
+const gchar *
+_gimp_unit_get_symbol (Gimp     *gimp,
+                       GimpUnit  unit)
+{
+  g_return_val_if_fail ((unit < (GIMP_UNIT_END + gimp->n_user_units)) ||
+                        (unit == GIMP_UNIT_PERCENT),
+                        gimp_unit_defs[GIMP_UNIT_INCH].symbol);
+
+  if (unit < GIMP_UNIT_END)
+    return gimp_unit_defs[unit].symbol;
+
+  if (unit == GIMP_UNIT_PERCENT)
+    return gimp_unit_percent.symbol;
+
+  return _gimp_unit_get_user_unit (gimp, unit)->symbol;
+}
+
+const gchar *
+_gimp_unit_get_abbreviation (Gimp     *gimp,
+                             GimpUnit  unit)
+{
+  g_return_val_if_fail ((unit < (GIMP_UNIT_END + gimp->n_user_units)) ||
+                        (unit == GIMP_UNIT_PERCENT),
+                        gimp_unit_defs[GIMP_UNIT_INCH].abbreviation);
+
+  if (unit < GIMP_UNIT_END)
+    return gimp_unit_defs[unit].abbreviation;
+
+  if (unit == GIMP_UNIT_PERCENT)
+    return gimp_unit_percent.abbreviation;
+
+  return _gimp_unit_get_user_unit (gimp, unit)->abbreviation;
+}
+
+const gchar *
+_gimp_unit_get_singular (Gimp     *gimp,
+                         GimpUnit  unit)
+{
+  g_return_val_if_fail ((unit < (GIMP_UNIT_END + gimp->n_user_units)) ||
+                        (unit == GIMP_UNIT_PERCENT),
+                        gimp_unit_defs[GIMP_UNIT_INCH].singular);
+
+  if (unit < GIMP_UNIT_END)
+    return g_dpgettext2 (NULL, "unit-singular", gimp_unit_defs[unit].singular);
+
+  if (unit == GIMP_UNIT_PERCENT)
+    return g_dpgettext2 (NULL, "unit-singular", gimp_unit_percent.singular);
+
+  return _gimp_unit_get_user_unit (gimp, unit)->singular;
+}
+
+const gchar *
+_gimp_unit_get_plural (Gimp     *gimp,
+                       GimpUnit  unit)
+{
+  g_return_val_if_fail ((unit < (GIMP_UNIT_END + gimp->n_user_units)) ||
+                        (unit == GIMP_UNIT_PERCENT),
+                        gimp_unit_defs[GIMP_UNIT_INCH].plural);
+
+  if (unit < GIMP_UNIT_END)
+    return g_dpgettext2 (NULL, "unit-plural", gimp_unit_defs[unit].plural);
+
+  if (unit == GIMP_UNIT_PERCENT)
+    return g_dpgettext2 (NULL, "unit-plural", gimp_unit_percent.plural);
+
+  return _gimp_unit_get_user_unit (gimp, unit)->plural;
+}
+
+
+/* The sole purpose of this function is to release the allocated
+ * memory. It must only be used from gimp_units_exit().
+ */
+void
+gimp_user_units_free (Gimp *gimp)
+{
+  GList *list;
+
+  for (list = gimp->user_units; list; list = g_list_next (list))
+    {
+      GimpUnitDef *user_unit = list->data;
+
+      g_free (user_unit->identifier);
+      g_free (user_unit->symbol);
+      g_free (user_unit->abbreviation);
+      g_free (user_unit->singular);
+      g_free (user_unit->plural);
+
+      g_slice_free (GimpUnitDef, user_unit);
+    }
+
+  g_list_free (gimp->user_units);
+  gimp->user_units   = NULL;
+  gimp->n_user_units = 0;
+}
diff --git a/app/core/gimpunit.h b/app/core/gimpunit.h
new file mode 100644
index 0000000..60dbc75
--- /dev/null
+++ b/app/core/gimpunit.h
@@ -0,0 +1,61 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __APP_GIMP_UNIT_H__
+#define __APP_GIMP_UNIT_H__
+
+
+gint          _gimp_unit_get_number_of_units          (Gimp        *gimp);
+gint          _gimp_unit_get_number_of_built_in_units (Gimp        *gimp) G_GNUC_CONST;
+
+GimpUnit      _gimp_unit_new                          (Gimp        *gimp,
+                                                       const gchar *identifier,
+                                                       gdouble      factor,
+                                                       gint         digits,
+                                                       const gchar *symbol,
+                                                       const gchar *abbreviation,
+                                                       const gchar *singular,
+                                                       const gchar *plural);
+
+gboolean      _gimp_unit_get_deletion_flag            (Gimp        *gimp,
+                                                       GimpUnit     unit);
+void          _gimp_unit_set_deletion_flag            (Gimp        *gimp,
+                                                       GimpUnit     unit,
+                                                       gboolean     deletion_flag);
+
+gdouble       _gimp_unit_get_factor                   (Gimp        *gimp,
+                                                       GimpUnit     unit);
+
+gint          _gimp_unit_get_digits                   (Gimp        *gimp,
+                                                       GimpUnit     unit);
+
+const gchar * _gimp_unit_get_identifier               (Gimp        *gimp,
+                                                       GimpUnit     unit);
+
+const gchar * _gimp_unit_get_symbol                   (Gimp        *gimp,
+                                                       GimpUnit     unit);
+const gchar * _gimp_unit_get_abbreviation             (Gimp        *gimp,
+                                                       GimpUnit     unit);
+const gchar * _gimp_unit_get_singular                 (Gimp        *gimp,
+                                                       GimpUnit     unit);
+const gchar * _gimp_unit_get_plural                   (Gimp        *gimp,
+                                                       GimpUnit     unit);
+
+void           gimp_user_units_free                   (Gimp        *gimp);
+
+
+#endif  /*  __APP_GIMP_UNIT_H__  */
diff --git a/app/core/gimpviewable.c b/app/core/gimpviewable.c
new file mode 100644
index 0000000..5b547a2
--- /dev/null
+++ b/app/core/gimpviewable.c
@@ -0,0 +1,1430 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1997 Spencer Kimball and Peter Mattis
+ *
+ * gimpviewable.c
+ * Copyright (C) 2001 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <cairo.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "libgimpcolor/gimpcolor.h"
+#include "libgimpmath/gimpmath.h"
+#include "libgimpconfig/gimpconfig.h"
+
+#include "core-types.h"
+
+#include "gimp-memsize.h"
+#include "gimpcontainer.h"
+#include "gimpcontext.h"
+#include "gimpmarshal.h"
+#include "gimptempbuf.h"
+#include "gimpviewable.h"
+
+#include "icons/Color/gimp-core-pixbufs.c"
+
+
+enum
+{
+  PROP_0,
+  PROP_STOCK_ID, /* compat */
+  PROP_ICON_NAME,
+  PROP_ICON_PIXBUF,
+  PROP_FROZEN
+};
+
+enum
+{
+  INVALIDATE_PREVIEW,
+  SIZE_CHANGED,
+  EXPANDED_CHANGED,
+  ANCESTRY_CHANGED,
+  LAST_SIGNAL
+};
+
+
+typedef struct _GimpViewablePrivate GimpViewablePrivate;
+
+struct _GimpViewablePrivate
+{
+  gchar        *icon_name;
+  GdkPixbuf    *icon_pixbuf;
+  gint          freeze_count;
+  gboolean      invalidate_pending;
+  gboolean      size_changed_prending;
+  GimpViewable *parent;
+  gint          depth;
+
+  GimpTempBuf  *preview_temp_buf;
+  GdkPixbuf    *preview_pixbuf;
+};
+
+#define GET_PRIVATE(viewable) ((GimpViewablePrivate *) gimp_viewable_get_instance_private ((GimpViewable *) (viewable)))
+
+
+static void    gimp_viewable_config_iface_init (GimpConfigInterface *iface);
+
+static void    gimp_viewable_finalize               (GObject        *object);
+static void    gimp_viewable_set_property           (GObject        *object,
+                                                     guint           property_id,
+                                                     const GValue   *value,
+                                                     GParamSpec     *pspec);
+static void    gimp_viewable_get_property           (GObject        *object,
+                                                     guint           property_id,
+                                                     GValue         *value,
+                                                     GParamSpec     *pspec);
+
+static gint64  gimp_viewable_get_memsize             (GimpObject    *object,
+                                                      gint64        *gui_size);
+
+static void    gimp_viewable_real_invalidate_preview (GimpViewable  *viewable);
+static void    gimp_viewable_real_ancestry_changed   (GimpViewable  *viewable);
+
+static GdkPixbuf * gimp_viewable_real_get_new_pixbuf (GimpViewable  *viewable,
+                                                      GimpContext   *context,
+                                                      gint           width,
+                                                      gint           height);
+static void    gimp_viewable_real_get_preview_size   (GimpViewable  *viewable,
+                                                      gint           size,
+                                                      gboolean       popup,
+                                                      gboolean       dot_for_dot,
+                                                      gint          *width,
+                                                      gint          *height);
+static gboolean gimp_viewable_real_get_popup_size    (GimpViewable  *viewable,
+                                                      gint           width,
+                                                      gint           height,
+                                                      gboolean       dot_for_dot,
+                                                      gint          *popup_width,
+                                                      gint          *popup_height);
+static gchar * gimp_viewable_real_get_description    (GimpViewable  *viewable,
+                                                      gchar        **tooltip);
+static gboolean gimp_viewable_real_is_name_editable  (GimpViewable  *viewable);
+static GimpContainer * gimp_viewable_real_get_children (GimpViewable *viewable);
+
+static gboolean gimp_viewable_serialize_property     (GimpConfig    *config,
+                                                      guint          property_id,
+                                                      const GValue  *value,
+                                                      GParamSpec    *pspec,
+                                                      GimpConfigWriter *writer);
+static gboolean gimp_viewable_deserialize_property   (GimpConfig       *config,
+                                                      guint             property_id,
+                                                      GValue           *value,
+                                                      GParamSpec       *pspec,
+                                                      GScanner         *scanner,
+                                                      GTokenType       *expected);
+
+
+G_DEFINE_TYPE_WITH_CODE (GimpViewable, gimp_viewable, GIMP_TYPE_OBJECT,
+                         G_ADD_PRIVATE (GimpViewable)
+                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_CONFIG,
+                                                gimp_viewable_config_iface_init))
+
+#define parent_class gimp_viewable_parent_class
+
+static guint viewable_signals[LAST_SIGNAL] = { 0 };
+
+
+static void
+gimp_viewable_class_init (GimpViewableClass *klass)
+{
+  GObjectClass    *object_class      = G_OBJECT_CLASS (klass);
+  GimpObjectClass *gimp_object_class = GIMP_OBJECT_CLASS (klass);
+
+  viewable_signals[INVALIDATE_PREVIEW] =
+    g_signal_new ("invalidate-preview",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpViewableClass, invalidate_preview),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  viewable_signals[SIZE_CHANGED] =
+    g_signal_new ("size-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpViewableClass, size_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  viewable_signals[EXPANDED_CHANGED] =
+    g_signal_new ("expanded-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpViewableClass, expanded_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  viewable_signals[ANCESTRY_CHANGED] =
+    g_signal_new ("ancestry-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpViewableClass, ancestry_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
+  object_class->finalize         = gimp_viewable_finalize;
+  object_class->get_property     = gimp_viewable_get_property;
+  object_class->set_property     = gimp_viewable_set_property;
+
+  gimp_object_class->get_memsize = gimp_viewable_get_memsize;
+
+  klass->default_icon_name       = "gimp-question";
+  klass->name_changed_signal     = "name-changed";
+  klass->name_editable           = FALSE;
+
+  klass->invalidate_preview      = gimp_viewable_real_invalidate_preview;
+  klass->size_changed            = NULL;
+  klass->expanded_changed        = NULL;
+  klass->ancestry_changed        = gimp_viewable_real_ancestry_changed;
+
+  klass->get_size                = NULL;
+  klass->get_preview_size        = gimp_viewable_real_get_preview_size;
+  klass->get_popup_size          = gimp_viewable_real_get_popup_size;
+  klass->get_preview             = NULL;
+  klass->get_new_preview         = NULL;
+  klass->get_pixbuf              = NULL;
+  klass->get_new_pixbuf          = gimp_viewable_real_get_new_pixbuf;
+  klass->get_description         = gimp_viewable_real_get_description;
+  klass->is_name_editable        = gimp_viewable_real_is_name_editable;
+  klass->preview_freeze          = NULL;
+  klass->preview_thaw            = NULL;
+  klass->get_children            = gimp_viewable_real_get_children;
+  klass->set_expanded            = NULL;
+  klass->get_expanded            = NULL;
+
+  /* compat property */
+  GIMP_CONFIG_PROP_STRING (object_class, PROP_STOCK_ID, "stock-id",
+                           NULL, NULL,
+                           NULL,
+                           GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_STRING (object_class, PROP_ICON_NAME, "icon-name",
+                           NULL, NULL,
+                           NULL,
+                           GIMP_PARAM_STATIC_STRINGS);
+
+  GIMP_CONFIG_PROP_OBJECT (object_class, PROP_ICON_PIXBUF,
+                           "icon-pixbuf",
+                           NULL, NULL,
+                           GDK_TYPE_PIXBUF,
+                           G_PARAM_CONSTRUCT |
+                           GIMP_PARAM_STATIC_STRINGS);
+
+  g_object_class_install_property (object_class, PROP_FROZEN,
+                                   g_param_spec_boolean ("frozen",
+                                                         NULL, NULL,
+                                                         FALSE,
+                                                         GIMP_PARAM_READABLE));
+}
+
+static void
+gimp_viewable_init (GimpViewable *viewable)
+{
+}
+
+static void
+gimp_viewable_config_iface_init (GimpConfigInterface *iface)
+{
+  iface->deserialize_property = gimp_viewable_deserialize_property;
+  iface->serialize_property   = gimp_viewable_serialize_property;
+}
+
+static void
+gimp_viewable_finalize (GObject *object)
+{
+  GimpViewablePrivate *private = GET_PRIVATE (object);
+
+  g_clear_pointer (&private->icon_name, g_free);
+  g_clear_object (&private->icon_pixbuf);
+  g_clear_pointer (&private->preview_temp_buf, gimp_temp_buf_unref);
+  g_clear_object (&private->preview_pixbuf);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gimp_viewable_set_property (GObject      *object,
+                            guint         property_id,
+                            const GValue *value,
+                            GParamSpec   *pspec)
+{
+  GimpViewable        *viewable = GIMP_VIEWABLE (object);
+  GimpViewablePrivate *private  = GET_PRIVATE (object);
+
+  switch (property_id)
+    {
+    case PROP_STOCK_ID:
+      if (! g_value_get_string (value))
+        break;
+    case PROP_ICON_NAME:
+      gimp_viewable_set_icon_name (viewable, g_value_get_string (value));
+      break;
+    case PROP_ICON_PIXBUF:
+      if (private->icon_pixbuf)
+        g_object_unref (private->icon_pixbuf);
+      private->icon_pixbuf = g_value_dup_object (value);
+      gimp_viewable_invalidate_preview (viewable);
+      break;
+    case PROP_FROZEN:
+      /* read-only, fall through */
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_viewable_get_property (GObject    *object,
+                            guint       property_id,
+                            GValue     *value,
+                            GParamSpec *pspec)
+{
+  GimpViewable        *viewable = GIMP_VIEWABLE (object);
+  GimpViewablePrivate *private  = GET_PRIVATE (object);
+
+  switch (property_id)
+    {
+    case PROP_STOCK_ID:
+    case PROP_ICON_NAME:
+      g_value_set_string (value, gimp_viewable_get_icon_name (viewable));
+      break;
+    case PROP_ICON_PIXBUF:
+      g_value_set_object (value, private->icon_pixbuf);
+      break;
+    case PROP_FROZEN:
+      g_value_set_boolean (value, gimp_viewable_preview_is_frozen (viewable));
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static gint64
+gimp_viewable_get_memsize (GimpObject *object,
+                           gint64     *gui_size)
+{
+  GimpViewablePrivate *private = GET_PRIVATE (object);
+
+  *gui_size += gimp_temp_buf_get_memsize (private->preview_temp_buf);
+
+  if (private->preview_pixbuf)
+    {
+      *gui_size +=
+        (gimp_g_object_get_memsize (G_OBJECT (private->preview_pixbuf)) +
+         (gsize) gdk_pixbuf_get_height (private->preview_pixbuf) *
+         gdk_pixbuf_get_rowstride (private->preview_pixbuf));
+    }
+
+  return GIMP_OBJECT_CLASS (parent_class)->get_memsize (object, gui_size);
+}
+
+static void
+gimp_viewable_real_invalidate_preview (GimpViewable *viewable)
+{
+  GimpViewablePrivate *private = GET_PRIVATE (viewable);
+
+  g_clear_pointer (&private->preview_temp_buf, gimp_temp_buf_unref);
+  g_clear_object (&private->preview_pixbuf);
+}
+
+static void
+gimp_viewable_real_ancestry_changed_propagate (GimpViewable *viewable,
+                                               GimpViewable *parent)
+{
+  GimpViewablePrivate *private = GET_PRIVATE (viewable);
+
+  private->depth = gimp_viewable_get_depth (parent) + 1;
+
+  g_signal_emit (viewable, viewable_signals[ANCESTRY_CHANGED], 0);
+}
+
+static void
+gimp_viewable_real_ancestry_changed (GimpViewable *viewable)
+{
+  GimpContainer *children;
+
+  children = gimp_viewable_get_children (viewable);
+
+  if (children)
+    {
+      gimp_container_foreach (children,
+                              (GFunc) gimp_viewable_real_ancestry_changed_propagate,
+                              viewable);
+    }
+}
+
+static void
+gimp_viewable_real_get_preview_size (GimpViewable *viewable,
+                                     gint          size,
+                                     gboolean      popup,
+                                     gboolean      dot_for_dot,
+                                     gint         *width,
+                                     gint         *height)
+{
+  *width  = size;
+  *height = size;
+}
+
+static gboolean
+gimp_viewable_real_get_popup_size (GimpViewable *viewable,
+                                   gint          width,
+                                   gint          height,
+                                   gboolean      dot_for_dot,
+                                   gint         *popup_width,
+                                   gint         *popup_height)
+{
+  gint w, h;
+
+  if (gimp_viewable_get_size (viewable, &w, &h))
+    {
+      if (w > width || h > height)
+        {
+          *popup_width  = w;
+          *popup_height = h;
+
+          return TRUE;
+        }
+    }
+
+  return FALSE;
+}
+
+static GdkPixbuf *
+gimp_viewable_real_get_new_pixbuf (GimpViewable *viewable,
+                                   GimpContext  *context,
+                                   gint          width,
+                                   gint          height)
+{
+  GimpViewablePrivate *private = GET_PRIVATE (viewable);
+  GdkPixbuf           *pixbuf  = NULL;
+  GimpTempBuf         *temp_buf;
+
+  temp_buf = gimp_viewable_get_preview (viewable, context, width, height);
+
+  if (temp_buf)
+    {
+      pixbuf = gimp_temp_buf_create_pixbuf (temp_buf);
+    }
+  else if (private->icon_pixbuf)
+    {
+      pixbuf = gdk_pixbuf_scale_simple (private->icon_pixbuf,
+                                        width,
+                                        height,
+                                        GDK_INTERP_BILINEAR);
+    }
+
+  return pixbuf;
+}
+
+static gchar *
+gimp_viewable_real_get_description (GimpViewable  *viewable,
+                                    gchar        **tooltip)
+{
+  return g_strdup (gimp_object_get_name (viewable));
+}
+
+static gboolean
+gimp_viewable_real_is_name_editable (GimpViewable *viewable)
+{
+  return GIMP_VIEWABLE_GET_CLASS (viewable)->name_editable;
+}
+
+static GimpContainer *
+gimp_viewable_real_get_children (GimpViewable *viewable)
+{
+  return NULL;
+}
+
+static gboolean
+gimp_viewable_serialize_property (GimpConfig       *config,
+                                  guint             property_id,
+                                  const GValue     *value,
+                                  GParamSpec       *pspec,
+                                  GimpConfigWriter *writer)
+{
+  GimpViewablePrivate *private = GET_PRIVATE (config);
+
+  switch (property_id)
+    {
+    case PROP_STOCK_ID:
+      return TRUE;
+
+    case PROP_ICON_NAME:
+      if (private->icon_name)
+        {
+          gimp_config_writer_open (writer, pspec->name);
+          gimp_config_writer_string (writer, private->icon_name);
+          gimp_config_writer_close (writer);
+        }
+      return TRUE;
+
+    case PROP_ICON_PIXBUF:
+      {
+        GdkPixbuf *icon_pixbuf = g_value_get_object (value);
+
+        if (icon_pixbuf)
+          {
+            gchar  *pixbuffer;
+            gsize   pixbuffer_size;
+            GError *error = NULL;
+
+            if (gdk_pixbuf_save_to_buffer (icon_pixbuf,
+                                           &pixbuffer,
+                                           &pixbuffer_size,
+                                           "png", &error, NULL))
+              {
+                gchar *pixbuffer_enc;
+
+                pixbuffer_enc = g_base64_encode ((guchar *)pixbuffer,
+                                                 pixbuffer_size);
+                gimp_config_writer_open (writer, "icon-pixbuf");
+                gimp_config_writer_string (writer, pixbuffer_enc);
+                gimp_config_writer_close (writer);
+
+                g_free (pixbuffer_enc);
+                g_free (pixbuffer);
+              }
+          }
+      }
+      return TRUE;
+
+    default:
+      break;
+    }
+
+  return FALSE;
+}
+
+static gboolean
+gimp_viewable_deserialize_property (GimpConfig *config,
+                                    guint       property_id,
+                                    GValue     *value,
+                                    GParamSpec *pspec,
+                                    GScanner   *scanner,
+                                    GTokenType *expected)
+{
+  switch (property_id)
+    {
+    case PROP_ICON_PIXBUF:
+      {
+        GdkPixbuf *icon_pixbuf = NULL;
+        gchar     *encoded_image;
+
+        if (! gimp_scanner_parse_string (scanner, &encoded_image))
+          {
+            *expected = G_TOKEN_STRING;
+            return TRUE;
+          }
+
+        if (encoded_image && strlen (encoded_image) > 0)
+          {
+            gsize   out_len;
+            guchar *decoded_image = g_base64_decode (encoded_image, &out_len);
+
+            if (decoded_image)
+              {
+                GInputStream *stream;
+
+                stream = g_memory_input_stream_new_from_data (decoded_image,
+                                                              out_len, NULL);
+                icon_pixbuf = gdk_pixbuf_new_from_stream (stream, NULL, NULL);
+                g_object_unref (stream);
+
+                g_free (decoded_image);
+              }
+          }
+
+        g_free (encoded_image);
+
+        g_value_take_object (value, icon_pixbuf);
+      }
+      return TRUE;
+
+    default:
+      break;
+    }
+
+  return FALSE;
+}
+
+/**
+ * gimp_viewable_invalidate_preview:
+ * @viewable: a viewable object
+ *
+ * Causes any cached preview to be marked as invalid, so that a new
+ * preview will be generated at the next attempt to display one.
+ **/
+void
+gimp_viewable_invalidate_preview (GimpViewable *viewable)
+{
+  GimpViewablePrivate *private;
+
+  g_return_if_fail (GIMP_IS_VIEWABLE (viewable));
+
+  private = GET_PRIVATE (viewable);
+
+  if (private->freeze_count == 0)
+    g_signal_emit (viewable, viewable_signals[INVALIDATE_PREVIEW], 0);
+  else
+    private->invalidate_pending = TRUE;
+}
+
+/**
+ * gimp_viewable_size_changed:
+ * @viewable: a viewable object
+ *
+ * This function sends a signal that is handled at a lower level in the
+ * object hierarchy, and provides a mechanism by which objects derived
+ * from #GimpViewable can respond to size changes.
+ **/
+void
+gimp_viewable_size_changed (GimpViewable *viewable)
+{
+  GimpViewablePrivate *private;
+
+  g_return_if_fail (GIMP_IS_VIEWABLE (viewable));
+
+  private = GET_PRIVATE (viewable);
+
+  if (private->freeze_count == 0)
+    g_signal_emit (viewable, viewable_signals[SIZE_CHANGED], 0);
+  else
+    private->size_changed_prending = TRUE;
+}
+
+/**
+ * gimp_viewable_expanded_changed:
+ * @viewable: a viewable object
+ *
+ * This function sends a signal that is handled at a lower level in the
+ * object hierarchy, and provides a mechanism by which objects derived
+ * from #GimpViewable can respond to expanded state changes.
+ **/
+void
+gimp_viewable_expanded_changed (GimpViewable *viewable)
+{
+  g_return_if_fail (GIMP_IS_VIEWABLE (viewable));
+
+  g_signal_emit (viewable, viewable_signals[EXPANDED_CHANGED], 0);
+}
+
+/**
+ * gimp_viewable_calc_preview_size:
+ * @aspect_width:   unscaled width of the preview for an item.
+ * @aspect_height:  unscaled height of the preview for an item.
+ * @width:          maximum available width for scaled preview.
+ * @height:         maximum available height for scaled preview.
+ * @dot_for_dot:    if #TRUE, ignore any differences in axis resolution.
+ * @xresolution:    resolution in the horizontal direction.
+ * @yresolution:    resolution in the vertical direction.
+ * @return_width:   place to return the calculated preview width.
+ * @return_height:  place to return the calculated preview height.
+ * @scaling_up:     returns #TRUE here if the calculated preview size
+ *                  is larger than the viewable itself.
+ *
+ * A utility function, for calculating the dimensions of a preview
+ * based on the information specified in the arguments.  The arguments
+ * @aspect_width and @aspect_height are the dimensions of the unscaled
+ * preview.  The arguments @width and @height represent the maximum
+ * width and height that the scaled preview must fit into. The
+ * preview is scaled to be as large as possible without exceeding
+ * these constraints.
+ *
+ * If @dot_for_dot is #TRUE, and @xresolution and @yresolution are
+ * different, then these results are corrected for the difference in
+ * resolution on the two axes, so that the requested aspect ratio
+ * applies to the appearance of the display rather than to pixel
+ * counts.
+ **/
+void
+gimp_viewable_calc_preview_size (gint       aspect_width,
+                                 gint       aspect_height,
+                                 gint       width,
+                                 gint       height,
+                                 gboolean   dot_for_dot,
+                                 gdouble    xresolution,
+                                 gdouble    yresolution,
+                                 gint      *return_width,
+                                 gint      *return_height,
+                                 gboolean  *scaling_up)
+{
+  gdouble xratio;
+  gdouble yratio;
+
+  if (aspect_width > aspect_height)
+    {
+      xratio = yratio = (gdouble) width / (gdouble) aspect_width;
+    }
+  else
+    {
+      xratio = yratio = (gdouble) height / (gdouble) aspect_height;
+    }
+
+  if (! dot_for_dot && xresolution != yresolution)
+    {
+      yratio *= xresolution / yresolution;
+    }
+
+  width  = RINT (xratio * (gdouble) aspect_width);
+  height = RINT (yratio * (gdouble) aspect_height);
+
+  if (width  < 1) width  = 1;
+  if (height < 1) height = 1;
+
+  if (return_width)  *return_width  = width;
+  if (return_height) *return_height = height;
+  if (scaling_up)    *scaling_up    = (xratio > 1.0) || (yratio > 1.0);
+}
+
+gboolean
+gimp_viewable_get_size (GimpViewable  *viewable,
+                        gint          *width,
+                        gint          *height)
+{
+  GimpViewableClass *viewable_class;
+  gboolean           retval = FALSE;
+  gint               w      = 0;
+  gint               h      = 0;
+
+  g_return_val_if_fail (GIMP_IS_VIEWABLE (viewable), FALSE);
+
+  viewable_class = GIMP_VIEWABLE_GET_CLASS (viewable);
+
+  if (viewable_class->get_size)
+    retval = viewable_class->get_size (viewable, &w, &h);
+
+  if (width)  *width  = w;
+  if (height) *height = h;
+
+  return retval;
+}
+
+/**
+ * gimp_viewable_get_preview_size:
+ * @viewable:    the object for which to calculate the preview size.
+ * @size:        requested size for preview.
+ * @popup:       %TRUE if the preview is intended for a popup window.
+ * @dot_for_dot: If #TRUE, ignore any differences in X and Y resolution.
+ * @width:       return location for the the calculated width.
+ * @height:      return location for the calculated height.
+ *
+ * Retrieve the size of a viewable's preview.  By default, this
+ * simply returns the value of the @size argument for both the @width
+ * and @height, but this can be overridden in objects derived from
+ * #GimpViewable.  If either the width or height exceeds
+ * #GIMP_VIEWABLE_MAX_PREVIEW_SIZE, they are silently truncated.
+ **/
+void
+gimp_viewable_get_preview_size (GimpViewable *viewable,
+                                gint          size,
+                                gboolean      popup,
+                                gboolean      dot_for_dot,
+                                gint         *width,
+                                gint         *height)
+{
+  gint w, h;
+
+  g_return_if_fail (GIMP_IS_VIEWABLE (viewable));
+  g_return_if_fail (size > 0);
+
+  GIMP_VIEWABLE_GET_CLASS (viewable)->get_preview_size (viewable, size,
+                                                        popup, dot_for_dot,
+                                                        &w, &h);
+
+  w = MIN (w, GIMP_VIEWABLE_MAX_PREVIEW_SIZE);
+  h = MIN (h, GIMP_VIEWABLE_MAX_PREVIEW_SIZE);
+
+  if (width)  *width  = w;
+  if (height) *height = h;
+
+}
+
+/**
+ * gimp_viewable_get_popup_size:
+ * @viewable:     the object for which to calculate the popup size.
+ * @width:        the width of the preview from which the popup will be shown.
+ * @height:       the height of the preview from which the popup will be shown.
+ * @dot_for_dot:  If #TRUE, ignore any differences in X and Y resolution.
+ * @popup_width:  return location for the calculated popup width.
+ * @popup_height: return location for the calculated popup height.
+ *
+ * Calculate the size of a viewable's preview, for use in making a
+ * popup. The arguments @width and @height specify the size of the
+ * preview from which the popup will be shown.
+ *
+ * Returns: Whether the viewable wants a popup to be shown. Usually
+ *          %TRUE if the passed preview size is smaller than the viewable
+ *          size, and %FALSE if the viewable completely fits into the
+ *          original preview.
+ **/
+gboolean
+gimp_viewable_get_popup_size (GimpViewable *viewable,
+                              gint          width,
+                              gint          height,
+                              gboolean      dot_for_dot,
+                              gint         *popup_width,
+                              gint         *popup_height)
+{
+  gint w, h;
+
+  g_return_val_if_fail (GIMP_IS_VIEWABLE (viewable), FALSE);
+
+  if (GIMP_VIEWABLE_GET_CLASS (viewable)->get_popup_size (viewable,
+                                                          width, height,
+                                                          dot_for_dot,
+                                                          &w, &h))
+    {
+      if (w < 1) w = 1;
+      if (h < 1) h = 1;
+
+      /*  limit the popup to 2 * GIMP_VIEWABLE_MAX_POPUP_SIZE
+       *  on each axis.
+       */
+      if ((w > (2 * GIMP_VIEWABLE_MAX_POPUP_SIZE)) ||
+          (h > (2 * GIMP_VIEWABLE_MAX_POPUP_SIZE)))
+        {
+          gimp_viewable_calc_preview_size (w, h,
+                                           2 * GIMP_VIEWABLE_MAX_POPUP_SIZE,
+                                           2 * GIMP_VIEWABLE_MAX_POPUP_SIZE,
+                                           dot_for_dot, 1.0, 1.0,
+                                           &w, &h, NULL);
+        }
+
+      /*  limit the number of pixels to
+       *  GIMP_VIEWABLE_MAX_POPUP_SIZE ^ 2
+       */
+      if ((w * h) > SQR (GIMP_VIEWABLE_MAX_POPUP_SIZE))
+        {
+          gdouble factor;
+
+          factor = sqrt (((gdouble) (w * h) /
+                          (gdouble) SQR (GIMP_VIEWABLE_MAX_POPUP_SIZE)));
+
+          w = RINT ((gdouble) w / factor);
+          h = RINT ((gdouble) h / factor);
+        }
+
+      if (w < 1) w = 1;
+      if (h < 1) h = 1;
+
+      if (popup_width)  *popup_width  = w;
+      if (popup_height) *popup_height = h;
+
+      return TRUE;
+    }
+
+  return FALSE;
+}
+
+/**
+ * gimp_viewable_get_preview:
+ * @viewable: The viewable object to get a preview for.
+ * @context:  The context to render the preview for.
+ * @width:    desired width for the preview
+ * @height:   desired height for the preview
+ *
+ * Gets a preview for a viewable object, by running through a variety
+ * of methods until it finds one that works.  First, if an
+ * implementation exists of a "get_preview" method, it is tried, and
+ * the result is returned if it is not #NULL.  Second, the function
+ * checks to see whether there is a cached preview with the correct
+ * dimensions; if so, it is returned.  If neither of these works, then
+ * the function looks for an implementation of the "get_new_preview"
+ * method, and executes it, caching the result.  If everything fails,
+ * #NULL is returned.
+ *
+ * Returns: A #GimpTempBuf containing the preview image, or #NULL if
+ *          none can be found or created.
+ **/
+GimpTempBuf *
+gimp_viewable_get_preview (GimpViewable *viewable,
+                           GimpContext  *context,
+                           gint          width,
+                           gint          height)
+{
+  GimpViewablePrivate *private;
+  GimpViewableClass   *viewable_class;
+  GimpTempBuf         *temp_buf = NULL;
+
+  g_return_val_if_fail (GIMP_IS_VIEWABLE (viewable), NULL);
+  g_return_val_if_fail (context == NULL || GIMP_IS_CONTEXT (context), NULL);
+  g_return_val_if_fail (width  > 0, NULL);
+  g_return_val_if_fail (height > 0, NULL);
+
+  private = GET_PRIVATE (viewable);
+
+  if (G_UNLIKELY (context == NULL))
+    g_warning ("%s: context is NULL", G_STRFUNC);
+
+  viewable_class = GIMP_VIEWABLE_GET_CLASS (viewable);
+
+  if (viewable_class->get_preview)
+    temp_buf = viewable_class->get_preview (viewable, context, width, height);
+
+  if (temp_buf)
+    return temp_buf;
+
+  if (private->preview_temp_buf)
+    {
+      if (gimp_temp_buf_get_width  (private->preview_temp_buf) == width &&
+          gimp_temp_buf_get_height (private->preview_temp_buf) == height)
+        {
+          return private->preview_temp_buf;
+        }
+
+      g_clear_pointer (&private->preview_temp_buf, gimp_temp_buf_unref);
+    }
+
+  if (viewable_class->get_new_preview)
+    temp_buf = viewable_class->get_new_preview (viewable, context,
+                                                width, height);
+
+  private->preview_temp_buf = temp_buf;
+
+  return temp_buf;
+}
+
+/**
+ * gimp_viewable_get_new_preview:
+ * @viewable: The viewable object to get a preview for.
+ * @width:    desired width for the preview
+ * @height:   desired height for the preview
+ *
+ * Gets a new preview for a viewable object.  Similar to
+ * gimp_viewable_get_preview(), except that it tries things in a
+ * different order, first looking for a "get_new_preview" method, and
+ * then if that fails for a "get_preview" method.  This function does
+ * not look for a cached preview.
+ *
+ * Returns: A #GimpTempBuf containing the preview image, or #NULL if
+ *          none can be found or created.
+ **/
+GimpTempBuf *
+gimp_viewable_get_new_preview (GimpViewable *viewable,
+                               GimpContext  *context,
+                               gint          width,
+                               gint          height)
+{
+  GimpViewableClass *viewable_class;
+  GimpTempBuf       *temp_buf = NULL;
+
+  g_return_val_if_fail (GIMP_IS_VIEWABLE (viewable), NULL);
+  g_return_val_if_fail (context == NULL || GIMP_IS_CONTEXT (context), NULL);
+  g_return_val_if_fail (width  > 0, NULL);
+  g_return_val_if_fail (height > 0, NULL);
+
+  if (G_UNLIKELY (context == NULL))
+    g_warning ("%s: context is NULL", G_STRFUNC);
+
+  viewable_class = GIMP_VIEWABLE_GET_CLASS (viewable);
+
+  if (viewable_class->get_new_preview)
+    temp_buf = viewable_class->get_new_preview (viewable, context,
+                                                width, height);
+
+  if (temp_buf)
+    return temp_buf;
+
+  if (viewable_class->get_preview)
+    temp_buf = viewable_class->get_preview (viewable, context,
+                                            width, height);
+
+  if (temp_buf)
+    return gimp_temp_buf_copy (temp_buf);
+
+  return NULL;
+}
+
+/**
+ * gimp_viewable_get_dummy_preview:
+ * @viewable: viewable object for which to get a dummy preview.
+ * @width:    width of the preview.
+ * @height:   height of the preview.
+ * @bpp:      bytes per pixel for the preview, must be 3 or 4.
+ *
+ * Creates a dummy preview the fits into the specified dimensions,
+ * containing a default "question" symbol.  This function is used to
+ * generate a preview in situations where layer previews have been
+ * disabled in the current Gimp configuration.
+ *
+ * Returns: a #GimpTempBuf containing the preview image.
+ **/
+GimpTempBuf *
+gimp_viewable_get_dummy_preview (GimpViewable *viewable,
+                                 gint          width,
+                                 gint          height,
+                                 const Babl   *format)
+{
+  GdkPixbuf   *pixbuf;
+  GimpTempBuf *buf;
+
+  g_return_val_if_fail (GIMP_IS_VIEWABLE (viewable), NULL);
+  g_return_val_if_fail (width  > 0, NULL);
+  g_return_val_if_fail (height > 0, NULL);
+  g_return_val_if_fail (format != NULL, NULL);
+
+  pixbuf = gimp_viewable_get_dummy_pixbuf (viewable, width, height,
+                                           babl_format_has_alpha (format));
+
+  buf = gimp_temp_buf_new_from_pixbuf (pixbuf, format);
+
+  g_object_unref (pixbuf);
+
+  return buf;
+}
+
+/**
+ * gimp_viewable_get_pixbuf:
+ * @viewable: The viewable object to get a pixbuf preview for.
+ * @context:  The context to render the preview for.
+ * @width:    desired width for the preview
+ * @height:   desired height for the preview
+ *
+ * Gets a preview for a viewable object, by running through a variety
+ * of methods until it finds one that works.  First, if an
+ * implementation exists of a "get_pixbuf" method, it is tried, and
+ * the result is returned if it is not #NULL.  Second, the function
+ * checks to see whether there is a cached preview with the correct
+ * dimensions; if so, it is returned.  If neither of these works, then
+ * the function looks for an implementation of the "get_new_pixbuf"
+ * method, and executes it, caching the result.  If everything fails,
+ * #NULL is returned.
+ *
+ * Returns: A #GdkPixbuf containing the preview pixbuf, or #NULL if none can
+ *          be found or created.
+ **/
+GdkPixbuf *
+gimp_viewable_get_pixbuf (GimpViewable *viewable,
+                          GimpContext  *context,
+                          gint          width,
+                          gint          height)
+{
+  GimpViewablePrivate *private;
+  GimpViewableClass   *viewable_class;
+  GdkPixbuf           *pixbuf = NULL;
+
+  g_return_val_if_fail (GIMP_IS_VIEWABLE (viewable), NULL);
+  g_return_val_if_fail (context == NULL || GIMP_IS_CONTEXT (context), NULL);
+  g_return_val_if_fail (width  > 0, NULL);
+  g_return_val_if_fail (height > 0, NULL);
+
+  private = GET_PRIVATE (viewable);
+
+  if (G_UNLIKELY (context == NULL))
+    g_warning ("%s: context is NULL", G_STRFUNC);
+
+  viewable_class = GIMP_VIEWABLE_GET_CLASS (viewable);
+
+  if (viewable_class->get_pixbuf)
+    pixbuf = viewable_class->get_pixbuf (viewable, context, width, height);
+
+  if (pixbuf)
+    return pixbuf;
+
+  if (private->preview_pixbuf)
+    {
+      if (gdk_pixbuf_get_width  (private->preview_pixbuf) == width &&
+          gdk_pixbuf_get_height (private->preview_pixbuf) == height)
+        {
+          return private->preview_pixbuf;
+        }
+
+      g_clear_object (&private->preview_pixbuf);
+    }
+
+  if (viewable_class->get_new_pixbuf)
+    pixbuf = viewable_class->get_new_pixbuf (viewable, context, width, height);
+
+  private->preview_pixbuf = pixbuf;
+
+  return pixbuf;
+}
+
+/**
+ * gimp_viewable_get_new_pixbuf:
+ * @viewable: The viewable object to get a new pixbuf preview for.
+ * @context:  The context to render the preview for.
+ * @width:    desired width for the pixbuf
+ * @height:   desired height for the pixbuf
+ *
+ * Gets a new preview for a viewable object.  Similar to
+ * gimp_viewable_get_pixbuf(), except that it tries things in a
+ * different order, first looking for a "get_new_pixbuf" method, and
+ * then if that fails for a "get_pixbuf" method.  This function does
+ * not look for a cached pixbuf.
+ *
+ * Returns: A #GdkPixbuf containing the preview, or #NULL if none can
+ *          be created.
+ **/
+GdkPixbuf *
+gimp_viewable_get_new_pixbuf (GimpViewable *viewable,
+                              GimpContext  *context,
+                              gint          width,
+                              gint          height)
+{
+  GimpViewableClass *viewable_class;
+  GdkPixbuf         *pixbuf = NULL;
+
+  g_return_val_if_fail (GIMP_IS_VIEWABLE (viewable), NULL);
+  g_return_val_if_fail (context == NULL || GIMP_IS_CONTEXT (context), NULL);
+  g_return_val_if_fail (width  > 0, NULL);
+  g_return_val_if_fail (height > 0, NULL);
+
+  if (G_UNLIKELY (context == NULL))
+    g_warning ("%s: context is NULL", G_STRFUNC);
+
+  viewable_class = GIMP_VIEWABLE_GET_CLASS (viewable);
+
+  if (viewable_class->get_new_pixbuf)
+    pixbuf = viewable_class->get_new_pixbuf (viewable, context, width, height);
+
+  if (pixbuf)
+    return pixbuf;
+
+  if (viewable_class->get_pixbuf)
+    pixbuf = viewable_class->get_pixbuf (viewable, context, width, height);
+
+  if (pixbuf)
+    return gdk_pixbuf_copy (pixbuf);
+
+  return NULL;
+}
+
+/**
+ * gimp_viewable_get_dummy_pixbuf:
+ * @viewable: the viewable object for which to create a dummy representation.
+ * @width:    maximum permitted width for the pixbuf.
+ * @height:   maximum permitted height for the pixbuf.
+ * @bpp:      bytes per pixel for the pixbuf, must equal 3 or 4.
+ *
+ * Creates a pixbuf containing a default "question" symbol, sized to
+ * fit into the specified dimensions.  The depth of the pixbuf must be
+ * 3 or 4 because #GdkPixbuf does not support grayscale.  This
+ * function is used to generate a preview in situations where
+ * previewing has been disabled in the current Gimp configuration.
+ * [Note: this function is currently unused except internally to
+ * #GimpViewable -- consider making it static?]
+ *
+ * Returns: the created #GdkPixbuf.
+ **/
+GdkPixbuf *
+gimp_viewable_get_dummy_pixbuf (GimpViewable  *viewable,
+                                gint           width,
+                                gint           height,
+                                gboolean       with_alpha)
+{
+  GdkPixbuf *icon;
+  GdkPixbuf *pixbuf;
+  GError    *error = NULL;
+  gdouble    ratio;
+  gint       w, h;
+
+  g_return_val_if_fail (GIMP_IS_VIEWABLE (viewable), NULL);
+  g_return_val_if_fail (width  > 0, NULL);
+  g_return_val_if_fail (height > 0, NULL);
+
+  icon = gdk_pixbuf_new_from_resource ("/org/gimp/icons/64/gimp-question.png",
+                                       &error);
+  if (! icon)
+    {
+      g_critical ("Failed to create icon image: %s", error->message);
+      g_clear_error (&error);
+      return NULL;
+    }
+
+  w = gdk_pixbuf_get_width (icon);
+  h = gdk_pixbuf_get_height (icon);
+
+  ratio = (gdouble) MIN (width, height) / (gdouble) MAX (w, h);
+  ratio = MIN (ratio, 1.0);
+
+  w = RINT (ratio * (gdouble) w);
+  h = RINT (ratio * (gdouble) h);
+
+  pixbuf = gdk_pixbuf_new (GDK_COLORSPACE_RGB, with_alpha, 8, width, height);
+  gdk_pixbuf_fill (pixbuf, 0xffffffff);
+
+  if (w && h)
+    gdk_pixbuf_composite (icon, pixbuf,
+                          (width - w) / 2, (height - h) / 2, w, h,
+                          (width - w) / 2, (height - h) / 2, ratio, ratio,
+                          GDK_INTERP_BILINEAR, 0xFF);
+
+  g_object_unref (icon);
+
+  return pixbuf;
+}
+
+/**
+ * gimp_viewable_get_description:
+ * @viewable: viewable object for which to retrieve a description.
+ * @tooltip:  return location for an optional tooltip string.
+ *
+ * Retrieves a string containing a description of the viewable object,
+ * By default, it simply returns the name of the object, but this can
+ * be overridden by object types that inherit from #GimpViewable.
+ *
+ * Returns: a copy of the description string.  This should be freed
+ *          when it is no longer needed.
+ **/
+gchar *
+gimp_viewable_get_description (GimpViewable  *viewable,
+                               gchar        **tooltip)
+{
+  g_return_val_if_fail (GIMP_IS_VIEWABLE (viewable), NULL);
+
+  if (tooltip)
+    *tooltip = NULL;
+
+  return GIMP_VIEWABLE_GET_CLASS (viewable)->get_description (viewable,
+                                                              tooltip);
+}
+
+/**
+ * gimp_viewable_is_name_editable:
+ * @viewable: viewable object for which to retrieve a description.
+ *
+ * Returns: whether the viewable's name is editable by the user.
+ **/
+gboolean
+gimp_viewable_is_name_editable (GimpViewable *viewable)
+{
+  g_return_val_if_fail (GIMP_IS_VIEWABLE (viewable), FALSE);
+
+  return GIMP_VIEWABLE_GET_CLASS (viewable)->is_name_editable (viewable);
+}
+
+/**
+ * gimp_viewable_get_icon_name:
+ * @viewable: viewable object for which to retrieve a icon name.
+ *
+ * Gets the current value of the object's icon name, for use in
+ * constructing an iconic representation of the object.
+ *
+ * Returns: a pointer to the string containing the icon name.  The
+ *          contents must not be altered or freed.
+ **/
+const gchar *
+gimp_viewable_get_icon_name (GimpViewable *viewable)
+{
+  GimpViewablePrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_VIEWABLE (viewable), NULL);
+
+  private = GET_PRIVATE (viewable);
+
+  if (private->icon_name)
+    return (const gchar *) private->icon_name;
+
+  return GIMP_VIEWABLE_GET_CLASS (viewable)->default_icon_name;
+}
+
+/**
+ * gimp_viewable_set_icon_name:
+ * @viewable: viewable object to assign the specified icon name.
+ * @icon_name: string containing an icon name identifier.
+ *
+ * Seta the object's icon name, for use in constructing iconic smbols
+ * of the object.  The contents of @icon_name are copied, so you can
+ * free it when you are done with it.
+ **/
+void
+gimp_viewable_set_icon_name (GimpViewable *viewable,
+                             const gchar  *icon_name)
+{
+  GimpViewablePrivate *private;
+  GimpViewableClass   *viewable_class;
+
+  g_return_if_fail (GIMP_IS_VIEWABLE (viewable));
+
+  private = GET_PRIVATE (viewable);
+
+  g_clear_pointer (&private->icon_name, g_free);
+
+  viewable_class = GIMP_VIEWABLE_GET_CLASS (viewable);
+
+  if (icon_name)
+    {
+      if (viewable_class->default_icon_name == NULL ||
+          strcmp (icon_name, viewable_class->default_icon_name))
+        private->icon_name = g_strdup (icon_name);
+    }
+
+  gimp_viewable_invalidate_preview (viewable);
+
+  g_object_notify (G_OBJECT (viewable), "icon-name");
+}
+
+void
+gimp_viewable_preview_freeze (GimpViewable *viewable)
+{
+  GimpViewablePrivate *private;
+
+  g_return_if_fail (GIMP_IS_VIEWABLE (viewable));
+
+  private = GET_PRIVATE (viewable);
+
+  private->freeze_count++;
+
+  if (private->freeze_count == 1)
+    {
+      if (GIMP_VIEWABLE_GET_CLASS (viewable)->preview_freeze)
+        GIMP_VIEWABLE_GET_CLASS (viewable)->preview_freeze (viewable);
+
+      g_object_notify (G_OBJECT (viewable), "frozen");
+    }
+}
+
+void
+gimp_viewable_preview_thaw (GimpViewable *viewable)
+{
+  GimpViewablePrivate *private;
+
+  g_return_if_fail (GIMP_IS_VIEWABLE (viewable));
+
+  private = GET_PRIVATE (viewable);
+
+  g_return_if_fail (private->freeze_count > 0);
+
+  private->freeze_count--;
+
+  if (private->freeze_count == 0)
+    {
+      if (private->size_changed_prending)
+        {
+          private->size_changed_prending = FALSE;
+
+          gimp_viewable_size_changed (viewable);
+        }
+
+      if (private->invalidate_pending)
+        {
+          private->invalidate_pending = FALSE;
+
+          gimp_viewable_invalidate_preview (viewable);
+        }
+
+      g_object_notify (G_OBJECT (viewable), "frozen");
+
+      if (GIMP_VIEWABLE_GET_CLASS (viewable)->preview_thaw)
+        GIMP_VIEWABLE_GET_CLASS (viewable)->preview_thaw (viewable);
+    }
+}
+
+gboolean
+gimp_viewable_preview_is_frozen (GimpViewable *viewable)
+{
+  g_return_val_if_fail (GIMP_IS_VIEWABLE (viewable), FALSE);
+
+  return GET_PRIVATE (viewable)->freeze_count != 0;
+}
+
+GimpViewable *
+gimp_viewable_get_parent (GimpViewable *viewable)
+{
+  g_return_val_if_fail (GIMP_IS_VIEWABLE (viewable), NULL);
+
+  return GET_PRIVATE (viewable)->parent;
+}
+
+void
+gimp_viewable_set_parent (GimpViewable *viewable,
+                          GimpViewable *parent)
+{
+  GimpViewablePrivate *private;
+
+  g_return_if_fail (GIMP_IS_VIEWABLE (viewable));
+  g_return_if_fail (parent == NULL || GIMP_IS_VIEWABLE (parent));
+
+  private = GET_PRIVATE (viewable);
+
+  if (parent != private->parent)
+    {
+      private->parent = parent;
+      private->depth  = parent ? gimp_viewable_get_depth (parent) + 1 : 0;
+
+      g_signal_emit (viewable, viewable_signals[ANCESTRY_CHANGED], 0);
+    }
+}
+
+gint
+gimp_viewable_get_depth (GimpViewable *viewable)
+{
+  g_return_val_if_fail (GIMP_IS_VIEWABLE (viewable), 0);
+
+  return GET_PRIVATE (viewable)->depth;
+}
+
+GimpContainer *
+gimp_viewable_get_children (GimpViewable *viewable)
+{
+  g_return_val_if_fail (GIMP_IS_VIEWABLE (viewable), NULL);
+
+  return GIMP_VIEWABLE_GET_CLASS (viewable)->get_children (viewable);
+}
+
+gboolean
+gimp_viewable_get_expanded (GimpViewable *viewable)
+{
+  g_return_val_if_fail (GIMP_IS_VIEWABLE (viewable), FALSE);
+
+  if (GIMP_VIEWABLE_GET_CLASS (viewable)->get_expanded)
+    return GIMP_VIEWABLE_GET_CLASS (viewable)->get_expanded (viewable);
+
+  return FALSE;
+}
+
+void
+gimp_viewable_set_expanded (GimpViewable *viewable,
+                            gboolean       expanded)
+{
+  g_return_if_fail (GIMP_IS_VIEWABLE (viewable));
+
+  if (GIMP_VIEWABLE_GET_CLASS (viewable)->set_expanded)
+    GIMP_VIEWABLE_GET_CLASS (viewable)->set_expanded (viewable, expanded);
+}
+
+gboolean
+gimp_viewable_is_ancestor (GimpViewable *ancestor,
+                           GimpViewable *descendant)
+{
+  g_return_val_if_fail (GIMP_IS_VIEWABLE (ancestor), FALSE);
+  g_return_val_if_fail (GIMP_IS_VIEWABLE (descendant), FALSE);
+
+  while (descendant)
+    {
+      GimpViewable *parent = gimp_viewable_get_parent (descendant);
+
+      if (parent == ancestor)
+        return TRUE;
+
+      descendant = parent;
+    }
+
+  return FALSE;
+}
diff --git a/app/core/gimpviewable.h b/app/core/gimpviewable.h
new file mode 100644
index 0000000..249750e
--- /dev/null
+++ b/app/core/gimpviewable.h
@@ -0,0 +1,201 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1997 Spencer Kimball and Peter Mattis
+ *
+ * gimpviewable.h
+ * Copyright (C) 2001 Michael Natterer <mitch@gimp.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_VIEWABLE_H__
+#define __GIMP_VIEWABLE_H__
+
+
+#include "gimpobject.h"
+
+
+#define GIMP_VIEWABLE_MAX_PREVIEW_SIZE 2048
+#define GIMP_VIEWABLE_MAX_POPUP_SIZE    256
+#define GIMP_VIEWABLE_MAX_BUTTON_SIZE    64
+#define GIMP_VIEWABLE_MAX_MENU_SIZE      48
+
+
+#define GIMP_TYPE_VIEWABLE            (gimp_viewable_get_type ())
+#define GIMP_VIEWABLE(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_VIEWABLE, GimpViewable))
+#define GIMP_VIEWABLE_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_VIEWABLE, GimpViewableClass))
+#define GIMP_IS_VIEWABLE(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_VIEWABLE))
+#define GIMP_IS_VIEWABLE_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_VIEWABLE))
+#define GIMP_VIEWABLE_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_VIEWABLE, GimpViewableClass))
+
+
+typedef struct _GimpViewableClass GimpViewableClass;
+
+struct _GimpViewable
+{
+  GimpObject  parent_instance;
+};
+
+struct _GimpViewableClass
+{
+  GimpObjectClass  parent_class;
+
+  const gchar     *default_icon_name;
+  const gchar     *name_changed_signal;
+  gboolean         name_editable;
+
+  /*  signals  */
+  void            (* invalidate_preview) (GimpViewable  *viewable);
+  void            (* size_changed)       (GimpViewable  *viewable);
+  void            (* expanded_changed)   (GimpViewable  *viewable);
+  void            (* ancestry_changed)   (GimpViewable  *viewable);
+
+  /*  virtual functions  */
+  gboolean        (* get_size)           (GimpViewable  *viewable,
+                                          gint          *width,
+                                          gint          *height);
+  void            (* get_preview_size)   (GimpViewable  *viewable,
+                                          gint           size,
+                                          gboolean       is_popup,
+                                          gboolean       dot_for_dot,
+                                          gint          *width,
+                                          gint          *height);
+  gboolean        (* get_popup_size)     (GimpViewable  *viewable,
+                                          gint           width,
+                                          gint           height,
+                                          gboolean       dot_for_dot,
+                                          gint          *popup_width,
+                                          gint          *popup_height);
+  GimpTempBuf   * (* get_preview)        (GimpViewable  *viewable,
+                                          GimpContext   *context,
+                                          gint           width,
+                                          gint           height);
+  GimpTempBuf   * (* get_new_preview)    (GimpViewable  *viewable,
+                                          GimpContext   *context,
+                                          gint           width,
+                                          gint           height);
+  GdkPixbuf     * (* get_pixbuf)         (GimpViewable  *viewable,
+                                          GimpContext   *context,
+                                          gint           width,
+                                          gint           height);
+  GdkPixbuf     * (* get_new_pixbuf)     (GimpViewable  *viewable,
+                                          GimpContext   *context,
+                                          gint           width,
+                                          gint           height);
+  gchar         * (* get_description)    (GimpViewable  *viewable,
+                                          gchar        **tooltip);
+
+  gboolean        (* is_name_editable)   (GimpViewable  *viewable);
+
+  void            (* preview_freeze)     (GimpViewable  *viewable);
+  void            (* preview_thaw)       (GimpViewable  *viewable);
+
+  GimpContainer * (* get_children)       (GimpViewable  *viewable);
+
+  void            (* set_expanded)       (GimpViewable  *viewable,
+                                          gboolean       expand);
+  gboolean        (* get_expanded)       (GimpViewable  *viewable);
+};
+
+
+GType           gimp_viewable_get_type           (void) G_GNUC_CONST;
+
+void            gimp_viewable_invalidate_preview (GimpViewable  *viewable);
+void            gimp_viewable_size_changed       (GimpViewable  *viewable);
+void            gimp_viewable_expanded_changed   (GimpViewable  *viewable);
+
+void            gimp_viewable_calc_preview_size  (gint           aspect_width,
+                                                  gint           aspect_height,
+                                                  gint           width,
+                                                  gint           height,
+                                                  gboolean       dot_for_dot,
+                                                  gdouble        xresolution,
+                                                  gdouble        yresolution,
+                                                  gint          *return_width,
+                                                  gint          *return_height,
+                                                  gboolean      *scaling_up);
+
+gboolean        gimp_viewable_get_size           (GimpViewable  *viewable,
+                                                  gint          *width,
+                                                  gint          *height);
+void            gimp_viewable_get_preview_size   (GimpViewable  *viewable,
+                                                  gint           size,
+                                                  gboolean       popup,
+                                                  gboolean       dot_for_dot,
+                                                  gint          *width,
+                                                  gint          *height);
+gboolean        gimp_viewable_get_popup_size     (GimpViewable  *viewable,
+                                                  gint           width,
+                                                  gint           height,
+                                                  gboolean       dot_for_dot,
+                                                  gint          *popup_width,
+                                                  gint          *popup_height);
+
+GimpTempBuf   * gimp_viewable_get_preview        (GimpViewable  *viewable,
+                                                  GimpContext   *context,
+                                                  gint           width,
+                                                  gint           height);
+GimpTempBuf   * gimp_viewable_get_new_preview    (GimpViewable  *viewable,
+                                                  GimpContext   *context,
+                                                  gint           width,
+                                                  gint           height);
+
+GimpTempBuf   * gimp_viewable_get_dummy_preview  (GimpViewable  *viewable,
+                                                  gint           width,
+                                                  gint           height,
+                                                  const Babl    *format);
+
+GdkPixbuf     * gimp_viewable_get_pixbuf         (GimpViewable  *viewable,
+                                                  GimpContext   *context,
+                                                  gint           width,
+                                                  gint           height);
+GdkPixbuf     * gimp_viewable_get_new_pixbuf     (GimpViewable  *viewable,
+                                                  GimpContext   *context,
+                                                  gint           width,
+                                                  gint           height);
+
+GdkPixbuf     * gimp_viewable_get_dummy_pixbuf   (GimpViewable  *viewable,
+                                                  gint           width,
+                                                  gint           height,
+                                                  gboolean       with_alpha);
+
+gchar         * gimp_viewable_get_description    (GimpViewable  *viewable,
+                                                  gchar        **tooltip);
+
+gboolean        gimp_viewable_is_name_editable   (GimpViewable  *viewable);
+
+const gchar   * gimp_viewable_get_icon_name      (GimpViewable  *viewable);
+void            gimp_viewable_set_icon_name      (GimpViewable  *viewable,
+                                                  const gchar   *icon_name);
+
+void            gimp_viewable_preview_freeze     (GimpViewable  *viewable);
+void            gimp_viewable_preview_thaw       (GimpViewable  *viewable);
+gboolean        gimp_viewable_preview_is_frozen  (GimpViewable  *viewable);
+
+GimpViewable  * gimp_viewable_get_parent         (GimpViewable  *viewable);
+void            gimp_viewable_set_parent         (GimpViewable  *viewable,
+                                                  GimpViewable  *parent);
+
+gint            gimp_viewable_get_depth          (GimpViewable  *viewable);
+
+GimpContainer * gimp_viewable_get_children       (GimpViewable  *viewable);
+
+gboolean        gimp_viewable_get_expanded       (GimpViewable  *viewable);
+void            gimp_viewable_set_expanded       (GimpViewable  *viewable,
+                                                  gboolean       expanded);
+
+gboolean        gimp_viewable_is_ancestor        (GimpViewable  *ancestor,
+                                                  GimpViewable  *descendant);
+
+
+#endif  /* __GIMP_VIEWABLE_H__ */
diff --git a/app/core/gimpwaitable.c b/app/core/gimpwaitable.c
new file mode 100644
index 0000000..4607f74
--- /dev/null
+++ b/app/core/gimpwaitable.c
@@ -0,0 +1,118 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimpwaitable.c
+ * Copyright (C) 2018 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+
+#include "config.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gegl.h>
+
+#include "core-types.h"
+
+#include "gimpwaitable.h"
+
+
+G_DEFINE_INTERFACE (GimpWaitable, gimp_waitable, G_TYPE_OBJECT)
+
+
+/*  private functions  */
+
+
+static void
+gimp_waitable_default_init (GimpWaitableInterface *iface)
+{
+}
+
+
+/*  public functions  */
+
+
+void
+gimp_waitable_wait (GimpWaitable *waitable)
+{
+  GimpWaitableInterface *iface;
+
+  g_return_if_fail (GIMP_IS_WAITABLE (waitable));
+
+  iface = GIMP_WAITABLE_GET_INTERFACE (waitable);
+
+  if (iface->wait)
+    iface->wait (waitable);
+}
+
+gboolean
+gimp_waitable_try_wait (GimpWaitable *waitable)
+{
+  GimpWaitableInterface *iface;
+
+  g_return_val_if_fail (GIMP_IS_WAITABLE (waitable), FALSE);
+
+  iface = GIMP_WAITABLE_GET_INTERFACE (waitable);
+
+  if (iface->try_wait)
+    {
+      return iface->try_wait (waitable);
+    }
+  else
+    {
+      gimp_waitable_wait (waitable);
+
+      return TRUE;
+    }
+}
+
+gboolean
+gimp_waitable_wait_until (GimpWaitable *waitable,
+                          gint64        end_time)
+{
+  GimpWaitableInterface *iface;
+
+  g_return_val_if_fail (GIMP_IS_WAITABLE (waitable), FALSE);
+
+  iface = GIMP_WAITABLE_GET_INTERFACE (waitable);
+
+  if (iface->wait_until)
+    {
+      return iface->wait_until (waitable, end_time);
+    }
+  else
+    {
+      gimp_waitable_wait (waitable);
+
+      return TRUE;
+    }
+}
+
+gboolean
+gimp_waitable_wait_for (GimpWaitable *waitable,
+                        gint64        wait_duration)
+{
+  g_return_val_if_fail (GIMP_IS_WAITABLE (waitable), FALSE);
+
+  if (wait_duration <= 0)
+    {
+      return gimp_waitable_try_wait (waitable);
+    }
+  else
+    {
+      return gimp_waitable_wait_until (waitable,
+                                       g_get_monotonic_time () + wait_duration);
+    }
+}
diff --git a/app/core/gimpwaitable.h b/app/core/gimpwaitable.h
new file mode 100644
index 0000000..b85bece
--- /dev/null
+++ b/app/core/gimpwaitable.h
@@ -0,0 +1,55 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995-1997 Spencer Kimball and Peter Mattis
+ *
+ * gimpwaitable.h
+ * Copyright (C) 2018 Ell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_WAITABLE_H__
+#define __GIMP_WAITABLE_H__
+
+
+#define GIMP_TYPE_WAITABLE               (gimp_waitable_get_type ())
+#define GIMP_IS_WAITABLE(obj)            (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_WAITABLE))
+#define GIMP_WAITABLE(obj)               (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_WAITABLE, GimpWaitable))
+#define GIMP_WAITABLE_GET_INTERFACE(obj) (G_TYPE_INSTANCE_GET_INTERFACE ((obj), GIMP_TYPE_WAITABLE, GimpWaitableInterface))
+
+
+typedef struct _GimpWaitableInterface GimpWaitableInterface;
+
+struct _GimpWaitableInterface
+{
+  GTypeInterface base_iface;
+
+  /*  virtual functions  */
+  void       (* wait)       (GimpWaitable *waitable);
+  gboolean   (* try_wait)   (GimpWaitable *waitable);
+  gboolean   (* wait_until) (GimpWaitable *waitable,
+                             gint64        end_time);
+};
+
+
+GType      gimp_waitable_get_type   (void) G_GNUC_CONST;
+
+void       gimp_waitable_wait       (GimpWaitable *waitable);
+gboolean   gimp_waitable_try_wait   (GimpWaitable *waitable);
+gboolean   gimp_waitable_wait_until (GimpWaitable *waitable,
+                                     gint64        end_time);
+gboolean   gimp_waitable_wait_for   (GimpWaitable *waitable,
+                                     gint64        wait_duration);
+
+
+#endif  /* __GIMP_WAITABLE_H__ */