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-rwxr-xr-xshare/extensions/path_envelope.py159
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diff --git a/share/extensions/path_envelope.py b/share/extensions/path_envelope.py
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+++ b/share/extensions/path_envelope.py
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+# coding=utf-8
+#
+# Copyright (C) 2005 Aaron Spike, aaron@ekips.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 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+#
+
+import inkex
+from inkex.transforms import DirectedLineSegment
+from inkex.localization import inkex_gettext as _
+from operator import truediv
+
+
+class Envelope(inkex.EffectExtension):
+ """Distort a path/group of paths to a second path"""
+
+ def effect(self):
+ if len(self.svg.selection) != 2:
+ raise inkex.AbortExtension(_("You must select two objects only."))
+
+ obj, envelope = self.svg.selection
+
+ if isinstance(obj, (inkex.PathElement, inkex.Group)):
+ if isinstance(envelope, inkex.PathElement):
+ # Get bounding box plus any extra composed transform of parents.
+ bbox = obj.bounding_box(obj.getparent().composed_transform())
+
+ # distill trafo into four node points
+ path = envelope.path.transform(
+ envelope.composed_transform()
+ ).to_superpath()
+ tbox = self.envelope_box_from_path(path)
+ else:
+ if isinstance(envelope, inkex.Group):
+ raise inkex.AbortExtension(
+ _(
+ "The second selected object is a group, not a"
+ " path.\nTry using Object->Ungroup."
+ )
+ )
+ raise inkex.AbortExtension(
+ _(
+ "The second selected object is not a path.\nTry using"
+ " the procedure Path->Object to Path."
+ )
+ )
+ else:
+ raise inkex.AbortExtension(
+ _(
+ "The first selected object is neither a path nor a group.\nTry using"
+ " the procedure Path->Object to Path."
+ )
+ )
+
+ self.process_object(obj, tbox, bbox)
+
+ def envelope_box_from_path(self, envelope_path):
+ if len(envelope_path) < 1 or len(envelope_path[0]) < 4:
+ raise inkex.AbortExtension(
+ _("Second selected path is too short. Must be four or more nodes.")
+ )
+ trafo = [[(csp[1][0], csp[1][1]) for csp in subs] for subs in envelope_path][0][
+ :4
+ ]
+ # vectors pointing away from the trafo origin
+ tbox = [
+ DirectedLineSegment(trafo[0], trafo[1]),
+ DirectedLineSegment(trafo[1], trafo[2]),
+ DirectedLineSegment(trafo[3], trafo[2]),
+ DirectedLineSegment(trafo[0], trafo[3]),
+ ]
+ vects = [segment.vector for segment in tbox]
+ if (
+ 0.0
+ == vects[0].cross(vects[1])
+ == vects[1].cross(vects[2])
+ == vects[2].cross(vects[3])
+ ):
+ raise inkex.AbortExtension(
+ _("The points for the selected envelope must not all be in a line.")
+ )
+ return tbox
+
+ def process_object(self, obj, tbox, bbox):
+ if isinstance(obj, inkex.PathElement):
+ self.process_path(obj, tbox, bbox)
+ elif isinstance(obj, inkex.Group):
+ self.process_group(obj, tbox, bbox)
+
+ def process_group(self, group, tbox, bbox):
+ """Go through all groups to process all paths inside them"""
+ for node in group:
+ self.process_object(node, tbox, bbox)
+
+ def process_path(self, element, tbox, bbox):
+ # Get out path's absolute and root coordinates, so obj and envelope
+ # are always in the same coordinate system.
+ points = (
+ element.path.to_absolute()
+ .transform(element.composed_transform())
+ .to_superpath()
+ )
+
+ for subs in points:
+ for csp in subs:
+ csp[0] = self.transform_point(tbox, bbox, *csp[0])
+ csp[1] = self.transform_point(tbox, bbox, *csp[1])
+ csp[2] = self.transform_point(tbox, bbox, *csp[2])
+
+ # Put the modified path back, undo the root transformation
+ element.path = points.to_path().transform(-element.composed_transform())
+
+ @staticmethod
+ def transform_point(tbox, bbox, x, y):
+ """Transform algorithm thanks to Jose Hevia (freon)"""
+ vector = (x, y) - bbox.minimum
+ xratio, yratio = map(truediv, vector, (bbox.width, bbox.height))
+ horz = DirectedLineSegment(
+ tbox[0].point_at_ratio(xratio), tbox[2].point_at_ratio(xratio)
+ )
+ vert = DirectedLineSegment(
+ tbox[3].point_at_ratio(yratio), tbox[1].point_at_ratio(yratio)
+ )
+ denom = horz.vector.cross(vert.vector)
+ if denom == 0.0:
+ # Degenerate cases of intersecting envelope edges
+ if horz.length == 0.0:
+ return horz.start
+ if vert.length == 0.0:
+ return vert.start
+ # Here we should know that the lines share a start or end point.
+ if horz.vector.dot(vert.vector) < 0:
+ # Segments point opposite directions
+ if (horz.start - vert.start).length <= 1e-8:
+ return horz.start
+ return horz.end
+ # Otherwise they are pointing the same direction
+ if (horz.start - vert.end).length < 1e-8:
+ return horz.start
+ return horz.end
+ # If we didn't hit a degenerate case we can treat the segments as infinite lines
+ intersect_ratio = (vert.start - horz.start).cross(vert.vector) / denom
+ return horz.point_at_ratio(intersect_ratio)
+
+
+if __name__ == "__main__":
+ Envelope().run()