Adding upstream version 2.10.36.upstream/2.10.36

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1956 insertions, 0 deletions

diff --git a/libgimpwidgets/gimppreviewarea.c b/libgimpwidgets/gimppreviewarea.c
new file mode 100644
index 0000000..7715ce0
--- /dev/null
+++ b/libgimpwidgets/gimppreviewarea.c
@@ -0,0 +1,1956 @@
+/* LIBGIMP - The GIMP Library
+ * Copyright (C) 1995-1997 Peter Mattis and Spencer Kimball
+ *
+ * This library is free software: you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library.  If not, see
+ * <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <gegl.h>
+#include <gtk/gtk.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpconfig/gimpconfig.h"
+#include "libgimpcolor/gimpcolor.h"
+
+#include "gimpwidgetstypes.h"
+
+#include "gimppreviewarea.h"
+#include "gimpwidgetsutils.h"
+
+#include "libgimp/libgimp-intl.h"
+
+
+/**
+ * SECTION: gimppreviewarea
+ * @title: GimpPreviewArea
+ * @short_description: A general purpose preview widget which caches
+ *                     its pixel data.
+ *
+ * A general purpose preview widget which caches its pixel data.
+ **/
+
+
+enum
+{
+  PROP_0,
+  PROP_CHECK_SIZE,
+  PROP_CHECK_TYPE
+};
+
+
+#define DEFAULT_CHECK_SIZE  GIMP_CHECK_SIZE_MEDIUM_CHECKS
+#define DEFAULT_CHECK_TYPE  GIMP_CHECK_TYPE_GRAY_CHECKS
+
+#define CHECK_COLOR(area, row, col)        \
+  (((((area)->offset_y + (row)) & size) ^  \
+    (((area)->offset_x + (col)) & size)) ? dark : light)
+
+
+typedef struct _GimpPreviewAreaPrivate GimpPreviewAreaPrivate;
+
+struct _GimpPreviewAreaPrivate
+{
+  GimpColorConfig    *config;
+  GimpColorTransform *transform;
+};
+
+#define GET_PRIVATE(obj) \
+        ((GimpPreviewAreaPrivate *) gimp_preview_area_get_instance_private ((GimpPreviewArea *) (obj)))
+
+
+static void      gimp_preview_area_dispose           (GObject          *object);
+static void      gimp_preview_area_finalize          (GObject          *object);
+static void      gimp_preview_area_set_property      (GObject          *object,
+                                                      guint             property_id,
+                                                      const GValue     *value,
+                                                      GParamSpec       *pspec);
+static void      gimp_preview_area_get_property      (GObject          *object,
+                                                      guint             property_id,
+                                                      GValue           *value,
+                                                      GParamSpec       *pspec);
+
+static void      gimp_preview_area_size_allocate     (GtkWidget        *widget,
+                                                      GtkAllocation    *allocation);
+static gboolean  gimp_preview_area_expose            (GtkWidget        *widget,
+                                                      GdkEventExpose   *event);
+
+static void      gimp_preview_area_queue_draw        (GimpPreviewArea  *area,
+                                                      gint              x,
+                                                      gint              y,
+                                                      gint              width,
+                                                      gint              height);
+static gint      gimp_preview_area_image_type_bytes  (GimpImageType     type);
+
+static void      gimp_preview_area_create_transform  (GimpPreviewArea  *area);
+static void      gimp_preview_area_destroy_transform (GimpPreviewArea  *area);
+
+
+G_DEFINE_TYPE_WITH_PRIVATE (GimpPreviewArea, gimp_preview_area,
+                            GTK_TYPE_DRAWING_AREA)
+
+#define parent_class gimp_preview_area_parent_class
+
+
+static void
+gimp_preview_area_class_init (GimpPreviewAreaClass *klass)
+{
+  GObjectClass   *object_class = G_OBJECT_CLASS (klass);
+  GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);
+
+  object_class->dispose       = gimp_preview_area_dispose;
+  object_class->finalize      = gimp_preview_area_finalize;
+  object_class->set_property  = gimp_preview_area_set_property;
+  object_class->get_property  = gimp_preview_area_get_property;
+
+  widget_class->size_allocate = gimp_preview_area_size_allocate;
+  widget_class->expose_event  = gimp_preview_area_expose;
+
+  g_object_class_install_property (object_class, PROP_CHECK_SIZE,
+                                   g_param_spec_enum ("check-size",
+                                                      _("Check Size"),
+                                                      "The size of the checkerboard pattern indicating transparency",
+                                                      GIMP_TYPE_CHECK_SIZE,
+                                                      DEFAULT_CHECK_SIZE,
+                                                      GIMP_PARAM_READWRITE));
+
+  g_object_class_install_property (object_class, PROP_CHECK_TYPE,
+                                   g_param_spec_enum ("check-type",
+                                                      _("Check Style"),
+                                                      "The colors of the checkerboard pattern indicating transparency",
+                                                      GIMP_TYPE_CHECK_TYPE,
+                                                      DEFAULT_CHECK_TYPE,
+                                                      GIMP_PARAM_READWRITE));
+}
+
+static void
+gimp_preview_area_init (GimpPreviewArea *area)
+{
+  area->check_size = DEFAULT_CHECK_SIZE;
+  area->check_type = DEFAULT_CHECK_TYPE;
+  area->buf        = NULL;
+  area->colormap   = NULL;
+  area->offset_x   = 0;
+  area->offset_y   = 0;
+  area->width      = 0;
+  area->height     = 0;
+  area->rowstride  = 0;
+  area->max_width  = -1;
+  area->max_height = -1;
+
+  gimp_widget_track_monitor (GTK_WIDGET (area),
+                             G_CALLBACK (gimp_preview_area_destroy_transform),
+                             NULL);
+}
+
+static void
+gimp_preview_area_dispose (GObject *object)
+{
+  GimpPreviewArea *area = GIMP_PREVIEW_AREA (object);
+
+  gimp_preview_area_set_color_config (area, NULL);
+
+  G_OBJECT_CLASS (parent_class)->dispose (object);
+}
+
+static void
+gimp_preview_area_finalize (GObject *object)
+{
+  GimpPreviewArea *area = GIMP_PREVIEW_AREA (object);
+
+  g_clear_pointer (&area->buf,      g_free);
+  g_clear_pointer (&area->colormap, g_free);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gimp_preview_area_set_property (GObject      *object,
+                                guint         property_id,
+                                const GValue *value,
+                                GParamSpec   *pspec)
+{
+  GimpPreviewArea *area = GIMP_PREVIEW_AREA (object);
+
+  switch (property_id)
+    {
+    case PROP_CHECK_SIZE:
+      area->check_size = g_value_get_enum (value);
+      break;
+    case PROP_CHECK_TYPE:
+      area->check_type = g_value_get_enum (value);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_preview_area_get_property (GObject    *object,
+                                guint       property_id,
+                                GValue     *value,
+                                GParamSpec *pspec)
+{
+  GimpPreviewArea *area = GIMP_PREVIEW_AREA (object);
+
+  switch (property_id)
+    {
+    case PROP_CHECK_SIZE:
+      g_value_set_enum (value, area->check_size);
+      break;
+    case PROP_CHECK_TYPE:
+      g_value_set_enum (value, area->check_type);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_preview_area_size_allocate (GtkWidget     *widget,
+                                 GtkAllocation *allocation)
+{
+  GimpPreviewArea *area = GIMP_PREVIEW_AREA (widget);
+  gint             width;
+  gint             height;
+
+  if (GTK_WIDGET_CLASS (parent_class)->size_allocate)
+    GTK_WIDGET_CLASS (parent_class)->size_allocate (widget, allocation);
+
+  width  = (area->max_width > 0 ?
+            MIN (allocation->width, area->max_width) : allocation->width);
+  height = (area->max_height > 0 ?
+            MIN (allocation->height, area->max_height) : allocation->height);
+
+  if (width  != area->width || height != area->height)
+    {
+      if (area->buf)
+        {
+          g_free (area->buf);
+
+          area->buf       = NULL;
+          area->rowstride = 0;
+        }
+
+      area->width  = width;
+      area->height = height;
+    }
+}
+
+static gboolean
+gimp_preview_area_expose (GtkWidget      *widget,
+                          GdkEventExpose *event)
+{
+  GimpPreviewArea        *area = GIMP_PREVIEW_AREA (widget);
+  GimpPreviewAreaPrivate *priv = GET_PRIVATE (area);
+  GtkAllocation           allocation;
+  GdkPixbuf              *pixbuf;
+  GdkRectangle            rect;
+  cairo_t                *cr;
+
+  if (! area->buf)
+    return FALSE;
+
+  gtk_widget_get_allocation (widget, &allocation);
+
+  rect.x      = (allocation.width  - area->width)  / 2;
+  rect.y      = (allocation.height - area->height) / 2;
+  rect.width  = area->width;
+  rect.height = area->height;
+
+  if (! priv->transform)
+    gimp_preview_area_create_transform (area);
+
+  if (priv->transform)
+    {
+      const Babl *format    = babl_format ("R'G'B' u8");
+      gint        rowstride = ((area->width * 3) + 3) & ~3;
+      guchar     *buf       = g_new (guchar, rowstride * area->height);
+      guchar     *src       = area->buf;
+      guchar     *dest      = buf;
+      gint        i;
+
+      for (i = 0; i < area->height; i++)
+        {
+          gimp_color_transform_process_pixels (priv->transform,
+                                               format, src,
+                                               format, dest,
+                                               area->width);
+
+          src  += area->rowstride;
+          dest += rowstride;
+        }
+
+      pixbuf = gdk_pixbuf_new_from_data (buf,
+                                         GDK_COLORSPACE_RGB,
+                                         FALSE,
+                                         8,
+                                         rect.width,
+                                         rect.height,
+                                         rowstride,
+                                         (GdkPixbufDestroyNotify) g_free, NULL);
+    }
+  else
+    {
+      pixbuf = gdk_pixbuf_new_from_data (area->buf,
+                                         GDK_COLORSPACE_RGB,
+                                         FALSE,
+                                         8,
+                                         rect.width,
+                                         rect.height,
+                                         area->rowstride,
+                                         NULL, NULL);
+    }
+
+  cr = gdk_cairo_create (gtk_widget_get_window (widget));
+
+  gdk_cairo_region (cr, event->region);
+  cairo_clip (cr);
+
+  gdk_cairo_set_source_pixbuf (cr, pixbuf, rect.x, rect.y);
+  cairo_paint (cr);
+
+  cairo_destroy (cr);
+  g_object_unref (pixbuf);
+
+  return FALSE;
+}
+
+static void
+gimp_preview_area_queue_draw (GimpPreviewArea *area,
+                              gint             x,
+                              gint             y,
+                              gint             width,
+                              gint             height)
+{
+  GtkWidget     *widget = GTK_WIDGET (area);
+  GtkAllocation  allocation;
+
+  gtk_widget_get_allocation (widget, &allocation);
+
+  x += (allocation.width  - area->width)  / 2;
+  y += (allocation.height - area->height) / 2;
+
+  gtk_widget_queue_draw_area (widget, x, y, width, height);
+}
+
+static gint
+gimp_preview_area_image_type_bytes (GimpImageType type)
+{
+  switch (type)
+    {
+    case GIMP_GRAY_IMAGE:
+    case GIMP_INDEXED_IMAGE:
+      return 1;
+
+    case GIMP_GRAYA_IMAGE:
+    case GIMP_INDEXEDA_IMAGE:
+      return 2;
+
+    case GIMP_RGB_IMAGE:
+      return 3;
+
+    case GIMP_RGBA_IMAGE:
+      return 4;
+
+    default:
+      g_return_val_if_reached (0);
+      break;
+    }
+}
+
+static void
+gimp_preview_area_create_transform (GimpPreviewArea *area)
+{
+  GimpPreviewAreaPrivate *priv = GET_PRIVATE (area);
+
+  if (priv->config)
+    {
+      static GimpColorProfile *profile = NULL;
+
+      const Babl *format = babl_format ("R'G'B' u8");
+
+      if (G_UNLIKELY (! profile))
+        profile = gimp_color_profile_new_rgb_srgb ();
+
+      priv->transform = gimp_widget_get_color_transform (GTK_WIDGET (area),
+                                                         priv->config,
+                                                         profile,
+                                                         format,
+                                                         format);
+    }
+}
+
+static void
+gimp_preview_area_destroy_transform (GimpPreviewArea *area)
+{
+  GimpPreviewAreaPrivate *priv = GET_PRIVATE (area);
+
+  if (priv->transform)
+    {
+      g_object_unref (priv->transform);
+      priv->transform = NULL;
+    }
+
+  gtk_widget_queue_draw (GTK_WIDGET (area));
+}
+
+
+/**
+ * gimp_preview_area_new:
+ *
+ * Creates a new #GimpPreviewArea widget.
+ *
+ * Return value: a new #GimpPreviewArea widget.
+ *
+ * Since GIMP 2.2
+ **/
+GtkWidget *
+gimp_preview_area_new (void)
+{
+  return g_object_new (GIMP_TYPE_PREVIEW_AREA, NULL);
+}
+
+/**
+ * gimp_preview_area_draw:
+ * @area:      a #GimpPreviewArea widget.
+ * @x:         x offset in preview
+ * @y:         y offset in preview
+ * @width:     buffer width
+ * @height:    buffer height
+ * @type:      the #GimpImageType of @buf
+ * @buf:       a #guchar buffer that contains the preview pixel data.
+ * @rowstride: rowstride of @buf
+ *
+ * Draws @buf on @area and queues a redraw on the given rectangle.
+ *
+ * Since GIMP 2.2
+ **/
+void
+gimp_preview_area_draw (GimpPreviewArea *area,
+                        gint             x,
+                        gint             y,
+                        gint             width,
+                        gint             height,
+                        GimpImageType    type,
+                        const guchar    *buf,
+                        gint             rowstride)
+{
+  const guchar *src;
+  guchar       *dest;
+  guint         size;
+  guchar        light;
+  guchar        dark;
+  gint          row;
+  gint          col;
+
+  g_return_if_fail (GIMP_IS_PREVIEW_AREA (area));
+  g_return_if_fail (width >= 0 && height >= 0);
+
+  if (width == 0 || height == 0)
+    return;
+
+  g_return_if_fail (buf != NULL);
+  g_return_if_fail (rowstride > 0);
+
+  if (x + width < 0 || x >= area->width)
+    return;
+
+  if (y + height < 0 || y >= area->height)
+    return;
+
+  if (x < 0)
+    {
+      gint bpp = gimp_preview_area_image_type_bytes (type);
+
+      buf -= x * bpp;
+      width += x;
+
+      x = 0;
+    }
+
+  if (x + width > area->width)
+    width = area->width - x;
+
+  if (y < 0)
+    {
+      buf -= y * rowstride;
+      height += y;
+
+      y = 0;
+    }
+
+  if (y + height > area->height)
+    height = area->height - y;
+
+  if (! area->buf)
+    {
+      area->rowstride = ((area->width * 3) + 3) & ~3;
+      area->buf = g_new (guchar, area->rowstride * area->height);
+    }
+
+  size = 1 << (2 + area->check_size);
+  gimp_checks_get_shades (area->check_type, &light, &dark);
+
+  src  = buf;
+  dest = area->buf + x * 3 + y * area->rowstride;
+
+  switch (type)
+    {
+    case GIMP_RGB_IMAGE:
+      for (row = 0; row < height; row++)
+        {
+          memcpy (dest, src, 3 * width);
+
+          src  += rowstride;
+          dest += area->rowstride;
+        }
+      break;
+
+    case GIMP_RGBA_IMAGE:
+       for (row = y; row < y + height; row++)
+        {
+          const guchar *s = src;
+          guchar       *d = dest;
+
+          for (col = x; col < x + width; col++, s += 4, d+= 3)
+            {
+              switch (s[3])
+                {
+                case 0:
+                  d[0] = d[1] = d[2] = CHECK_COLOR (area, row, col);
+                  break;
+
+                case 255:
+                  d[0] = s[0];
+                  d[1] = s[1];
+                  d[2] = s[2];
+                  break;
+
+                default:
+                  {
+                    register guint alpha = s[3] + 1;
+                    register guint check = CHECK_COLOR (area, row, col);
+
+                    d[0] = ((check << 8) + (s[0] - check) * alpha) >> 8;
+                    d[1] = ((check << 8) + (s[1] - check) * alpha) >> 8;
+                    d[2] = ((check << 8) + (s[2] - check) * alpha) >> 8;
+                  }
+                  break;
+                }
+            }
+
+          src  += rowstride;
+          dest += area->rowstride;
+        }
+       break;
+
+    case GIMP_GRAY_IMAGE:
+      for (row = 0; row < height; row++)
+        {
+          const guchar *s = src;
+          guchar       *d = dest;
+
+          for (col = 0; col < width; col++, s++, d += 3)
+            {
+              d[0] = d[1] = d[2] = s[0];
+            }
+
+          src  += rowstride;
+          dest += area->rowstride;
+        }
+      break;
+
+    case GIMP_GRAYA_IMAGE:
+      for (row = y; row < y + height; row++)
+        {
+          const guchar *s = src;
+          guchar       *d = dest;
+
+          for (col = x; col < x + width; col++, s += 2, d+= 3)
+            {
+              switch (s[1])
+                {
+                case 0:
+                  d[0] = d[1] = d[2] = CHECK_COLOR (area, row, col);
+                  break;
+
+                case 255:
+                  d[0] = d[1] = d[2] = s[0];
+                  break;
+
+                default:
+                  {
+                    register guint alpha = s[1] + 1;
+                    register guint check = CHECK_COLOR (area, row, col);
+
+                    d[0] = d[1] = d[2] =
+                      ((check << 8) + (s[0] - check) * alpha) >> 8;
+                  }
+                  break;
+                }
+            }
+
+          src  += rowstride;
+          dest += area->rowstride;
+        }
+      break;
+
+    case GIMP_INDEXED_IMAGE:
+      g_return_if_fail (area->colormap != NULL);
+      for (row = 0; row < height; row++)
+        {
+          const guchar *s = src;
+          guchar       *d = dest;
+
+          for (col = 0; col < width; col++, s++, d += 3)
+            {
+              const guchar *colormap = area->colormap + 3 * s[0];
+
+              d[0] = colormap[0];
+              d[1] = colormap[1];
+              d[2] = colormap[2];
+            }
+
+          src  += rowstride;
+          dest += area->rowstride;
+        }
+      break;
+
+    case GIMP_INDEXEDA_IMAGE:
+      g_return_if_fail (area->colormap != NULL);
+      for (row = y; row < y + height; row++)
+        {
+          const guchar *s = src;
+          guchar       *d = dest;
+
+          for (col = x; col < x + width; col++, s += 2, d += 3)
+            {
+              const guchar *colormap  = area->colormap + 3 * s[0];
+
+              switch (s[1])
+                {
+                case 0:
+                  d[0] = d[1] = d[2] = CHECK_COLOR (area, row, col);
+                  break;
+
+                case 255:
+                  d[0] = colormap[0];
+                  d[1] = colormap[1];
+                  d[2] = colormap[2];
+                  break;
+
+                default:
+                  {
+                    register guint alpha = s[3] + 1;
+                    register guint check = CHECK_COLOR (area, row, col);
+
+                    d[0] = ((check << 8) + (colormap[0] - check) * alpha) >> 8;
+                    d[1] = ((check << 8) + (colormap[1] - check) * alpha) >> 8;
+                    d[2] = ((check << 8) + (colormap[2] - check) * alpha) >> 8;
+                  }
+                  break;
+                }
+            }
+
+          src  += rowstride;
+          dest += area->rowstride;
+        }
+      break;
+    }
+
+  gimp_preview_area_queue_draw (area, x, y, width, height);
+}
+
+/**
+ * gimp_preview_area_blend:
+ * @area:       a #GimpPreviewArea widget.
+ * @x:          x offset in preview
+ * @y:          y offset in preview
+ * @width:      buffer width
+ * @height:     buffer height
+ * @type:       the #GimpImageType of @buf1 and @buf2
+ * @buf1:       a #guchar buffer that contains the pixel data for
+ *              the lower layer
+ * @rowstride1: rowstride of @buf1
+ * @buf2:       a #guchar buffer that contains the pixel data for
+ *              the upper layer
+ * @rowstride2: rowstride of @buf2
+ * @opacity:    The opacity of the first layer.
+ *
+ * Composites @buf1 on @buf2 with the given @opacity, draws the result
+ * to @area and queues a redraw on the given rectangle.
+ *
+ * Since GIMP 2.2
+ **/
+void
+gimp_preview_area_blend (GimpPreviewArea *area,
+                         gint             x,
+                         gint             y,
+                         gint             width,
+                         gint             height,
+                         GimpImageType    type,
+                         const guchar    *buf1,
+                         gint             rowstride1,
+                         const guchar    *buf2,
+                         gint             rowstride2,
+                         guchar           opacity)
+{
+  const guchar *src1;
+  const guchar *src2;
+  guchar       *dest;
+  guint         size;
+  guchar        light;
+  guchar        dark;
+  gint          row;
+  gint          col;
+  gint          i;
+
+  g_return_if_fail (GIMP_IS_PREVIEW_AREA (area));
+  g_return_if_fail (width >= 0 && height >= 0);
+
+  if (width == 0 || height == 0)
+    return;
+
+  g_return_if_fail (buf1 != NULL);
+  g_return_if_fail (buf2 != NULL);
+  g_return_if_fail (rowstride1 > 0);
+  g_return_if_fail (rowstride2 > 0);
+
+  switch (opacity)
+    {
+    case 0:
+      gimp_preview_area_draw (area, x, y, width, height,
+                              type, buf1, rowstride1);
+      return;
+
+    case 255:
+      gimp_preview_area_draw (area, x, y, width, height,
+                              type, buf2, rowstride2);
+      return;
+
+    default:
+      break;
+    }
+
+  if (x + width < 0 || x >= area->width)
+    return;
+
+  if (y + height < 0 || y >= area->height)
+    return;
+
+  if (x < 0)
+    {
+      gint bpp = gimp_preview_area_image_type_bytes (type);
+
+      buf1 -= x * bpp;
+      buf2 -= x * bpp;
+      width += x;
+
+      x = 0;
+    }
+
+  if (x + width > area->width)
+    width = area->width - x;
+
+  if (y < 0)
+    {
+      buf1 -= y * rowstride1;
+      buf2 -= y * rowstride2;
+      height += y;
+
+      y = 0;
+    }
+
+  if (y + height > area->height)
+    height = area->height - y;
+
+  if (! area->buf)
+    {
+      area->rowstride = ((area->width * 3) + 3) & ~3;
+      area->buf = g_new (guchar, area->rowstride * area->height);
+    }
+
+  size = 1 << (2 + area->check_size);
+  gimp_checks_get_shades (area->check_type, &light, &dark);
+
+  src1 = buf1;
+  src2 = buf2;
+  dest = area->buf + x * 3 + y * area->rowstride;
+
+  switch (type)
+    {
+    case GIMP_RGB_IMAGE:
+      for (row = 0; row < height; row++)
+        {
+          const guchar *s1 = src1;
+          const guchar *s2 = src2;
+          guchar       *d  = dest;
+
+          for (col = x; col < x + width; col++, s1 += 3, s2 += 3, d+= 3)
+            {
+              d[0] = ((s1[0] << 8) + (s2[0] - s1[0]) * opacity) >> 8;
+              d[1] = ((s1[1] << 8) + (s2[1] - s1[1]) * opacity) >> 8;
+              d[2] = ((s1[2] << 8) + (s2[2] - s1[2]) * opacity) >> 8;
+            }
+
+          src1 += rowstride1;
+          src2 += rowstride2;
+          dest += area->rowstride;
+        }
+      break;
+
+    case GIMP_RGBA_IMAGE:
+      for (row = y; row < y + height; row++)
+        {
+          const guchar *s1 = src1;
+          const guchar *s2 = src2;
+          guchar       *d  = dest;
+
+          for (col = x; col < x + width; col++, s1 += 4, s2 += 4, d+= 3)
+            {
+              guchar inter[4];
+
+              if (s1[3] == s2[3])
+                {
+                  inter[0] = ((s1[0] << 8) + (s2[0] - s1[0]) * opacity) >> 8;
+                  inter[1] = ((s1[1] << 8) + (s2[1] - s1[1]) * opacity) >> 8;
+                  inter[2] = ((s1[2] << 8) + (s2[2] - s1[2]) * opacity) >> 8;
+                  inter[3] = s1[3];
+                }
+              else
+                {
+                  inter[3] = ((s1[3] << 8) + (s2[3] - s1[3]) * opacity) >> 8;
+
+                  if (inter[3])
+                    {
+                      for (i = 0; i < 3; i++)
+                        {
+                          gushort a = s1[i] * s1[3];
+                          gushort b = s2[i] * s2[3];
+
+                          inter[i] =
+                            (((a << 8) + (b  - a) * opacity) >> 8) / inter[3];
+                        }
+                    }
+                }
+
+              switch (inter[3])
+                {
+                case 0:
+                  d[0] = d[1] = d[2] = CHECK_COLOR (area, row, col);
+                  break;
+
+                case 255:
+                  d[0] = inter[0];
+                  d[1] = inter[1];
+                  d[2] = inter[2];
+                  break;
+
+                default:
+                  {
+                    register guint alpha = inter[3] + 1;
+                    register guint check = CHECK_COLOR (area, row, col);
+
+                    d[0] = ((check << 8) + (inter[0] - check) * alpha) >> 8;
+                    d[1] = ((check << 8) + (inter[1] - check) * alpha) >> 8;
+                    d[2] = ((check << 8) + (inter[2] - check) * alpha) >> 8;
+                  }
+                  break;
+                }
+            }
+
+          src1 += rowstride1;
+          src2 += rowstride2;
+          dest += area->rowstride;
+        }
+      break;
+
+    case GIMP_GRAY_IMAGE:
+      for (row = 0; row < height; row++)
+        {
+          const guchar *s1 = src1;
+          const guchar *s2 = src2;
+          guchar       *d  = dest;
+
+          for (col = 0; col < width; col++, s1++, s2++, d += 3)
+            {
+              d[0] = d[1] = d[2] =
+                ((s1[0] << 8) + (s2[0] - s1[0]) * opacity) >> 8;
+            }
+
+          src1 += rowstride1;
+          src2 += rowstride2;
+          dest += area->rowstride;
+        }
+      break;
+
+    case GIMP_GRAYA_IMAGE:
+      for (row = y; row < y + height; row++)
+        {
+          const guchar *s1 = src1;
+          const guchar *s2 = src2;
+          guchar       *d  = dest;
+
+          for (col = x; col < x + width; col++, s1 += 2, s2 += 2, d+= 3)
+            {
+              guchar inter[2] = { 0, };
+
+              if (s1[1] == s2[1])
+                {
+                  inter[0] = ((s1[0] << 8) + (s2[0] - s1[0]) * opacity) >> 8;
+                  inter[1] = s1[1];
+                }
+              else
+                {
+                  inter[1] = ((s1[1] << 8) + (s2[1] - s1[1]) * opacity) >> 8;
+
+                  if (inter[1])
+                    {
+                      gushort a = s1[0] * s1[1];
+                      gushort b = s2[0] * s2[1];
+
+                      inter[0] =
+                        (((a << 8) + (b  - a) * opacity) >> 8) / inter[1];
+                    }
+                }
+
+              switch (inter[1])
+                {
+                case 0:
+                  d[0] = d[1] = d[2] = CHECK_COLOR (area, row, col);
+                  break;
+
+                case 255:
+                  d[0] = d[1] = d[2] = inter[0];
+                  break;
+
+                default:
+                  {
+                    register guint alpha = inter[1] + 1;
+                    register guint check = CHECK_COLOR (area, row, col);
+
+                    d[0] = d[1] = d[2] =
+                      ((check << 8) + (inter[0] - check) * alpha) >> 8;
+                  }
+                  break;
+                }
+            }
+
+          src1 += rowstride1;
+          src2 += rowstride2;
+          dest += area->rowstride;
+        }
+      break;
+
+    case GIMP_INDEXED_IMAGE:
+      g_return_if_fail (area->colormap != NULL);
+      for (row = 0; row < height; row++)
+        {
+          const guchar *s1 = src1;
+          const guchar *s2 = src2;
+          guchar       *d  = dest;
+
+          for (col = 0; col < width; col++, s1++, s2++, d += 3)
+            {
+              const guchar *cmap1 = area->colormap + 3 * s1[0];
+              const guchar *cmap2 = area->colormap + 3 * s2[0];
+
+              d[0] = ((cmap1[0] << 8) + (cmap2[0] - cmap1[0]) * opacity) >> 8;
+              d[1] = ((cmap1[1] << 8) + (cmap2[1] - cmap1[1]) * opacity) >> 8;
+              d[2] = ((cmap1[2] << 8) + (cmap2[2] - cmap1[2]) * opacity) >> 8;
+            }
+
+          src1 += rowstride1;
+          src2 += rowstride2;
+          dest += area->rowstride;
+        }
+      break;
+
+    case GIMP_INDEXEDA_IMAGE:
+      g_return_if_fail (area->colormap != NULL);
+      for (row = y; row < y + height; row++)
+        {
+          const guchar *s1 = src1;
+          const guchar *s2 = src2;
+          guchar       *d  = dest;
+
+          for (col = x; col < x + width; col++, s1 += 2, s2 += 2, d += 3)
+            {
+              const guchar *cmap1  = area->colormap + 3 * s1[0];
+              const guchar *cmap2  = area->colormap + 3 * s2[0];
+              guchar        inter[4];
+
+              if (s1[1] == s2[1])
+                {
+                  inter[0] = (((cmap1[0] << 8) +
+                               (cmap2[0] - cmap1[0]) * opacity) >> 8);
+                  inter[1] = (((cmap1[1] << 8) +
+                               (cmap2[1] - cmap1[1]) * opacity) >> 8);
+                  inter[2] = (((cmap1[2] << 8) +
+                               (cmap2[2] - cmap1[2]) * opacity) >> 8);
+                  inter[3] = s1[1];
+                }
+              else
+                {
+                  inter[3] = ((s1[1] << 8) + (s2[1] - s1[1]) * opacity) >> 8;
+
+                  if (inter[3])
+                    {
+                      for (i = 0; i < 3; i++)
+                        {
+                          gushort a = cmap1[i] * s1[1];
+                          gushort b = cmap2[i] * s2[1];
+
+                          inter[i] =
+                            (((a << 8) + (b  - a) * opacity) >> 8) / inter[3];
+                        }
+                    }
+                }
+
+              switch (inter[3])
+                {
+                case 0:
+                  d[0] = d[1] = d[2] = CHECK_COLOR (area, row, col);
+                  break;
+
+                case 255:
+                  d[0] = inter[0];
+                  d[1] = inter[1];
+                  d[2] = inter[2];
+                  break;
+
+                default:
+                  {
+                    register guint alpha = inter[3] + 1;
+                    register guint check = CHECK_COLOR (area, row, col);
+
+                    d[0] = ((check << 8) + (inter[0] - check) * alpha) >> 8;
+                    d[1] = ((check << 8) + (inter[1] - check) * alpha) >> 8;
+                    d[2] = ((check << 8) + (inter[2] - check) * alpha) >> 8;
+                  }
+                  break;
+                }
+            }
+
+          src1 += rowstride1;
+          src2 += rowstride2;
+          dest += area->rowstride;
+        }
+      break;
+    }
+
+  gimp_preview_area_queue_draw (area, x, y, width, height);
+}
+
+/**
+ * gimp_preview_area_mask:
+ * @area:           a #GimpPreviewArea widget.
+ * @x:              x offset in preview
+ * @y:              y offset in preview
+ * @width:          buffer width
+ * @height:         buffer height
+ * @type:           the #GimpImageType of @buf1 and @buf2
+ * @buf1:           a #guchar buffer that contains the pixel data for
+ *                  the lower layer
+ * @rowstride1:     rowstride of @buf1
+ * @buf2:           a #guchar buffer that contains the pixel data for
+ *                  the upper layer
+ * @rowstride2:     rowstride of @buf2
+ * @mask:           a #guchar buffer representing the mask of the second
+ *                  layer.
+ * @rowstride_mask: rowstride for the mask.
+ *
+ * Composites @buf1 on @buf2 with the given @mask, draws the result on
+ * @area and queues a redraw on the given rectangle.
+ *
+ * Since GIMP 2.2
+ **/
+void
+gimp_preview_area_mask (GimpPreviewArea *area,
+                        gint             x,
+                        gint             y,
+                        gint             width,
+                        gint             height,
+                        GimpImageType    type,
+                        const guchar    *buf1,
+                        gint             rowstride1,
+                        const guchar    *buf2,
+                        gint             rowstride2,
+                        const guchar    *mask,
+                        gint             rowstride_mask)
+{
+  const guchar *src1;
+  const guchar *src2;
+  const guchar *src_mask;
+  guchar       *dest;
+  guint         size;
+  guchar        light;
+  guchar        dark;
+  gint          row;
+  gint          col;
+  gint          i;
+
+  g_return_if_fail (GIMP_IS_PREVIEW_AREA (area));
+  g_return_if_fail (width >= 0 && height >= 0);
+
+  if (width == 0 || height == 0)
+    return;
+
+  g_return_if_fail (buf1 != NULL);
+  g_return_if_fail (buf2 != NULL);
+  g_return_if_fail (mask != NULL);
+  g_return_if_fail (rowstride1 > 0);
+  g_return_if_fail (rowstride2 > 0);
+  g_return_if_fail (rowstride_mask > 0);
+
+  if (x + width < 0 || x >= area->width)
+    return;
+
+  if (y + height < 0 || y >= area->height)
+    return;
+
+  if (x < 0)
+    {
+      gint bpp = gimp_preview_area_image_type_bytes (type);
+
+      buf1 -= x * bpp;
+      buf2 -= x * bpp;
+      mask -= x;
+      width += x;
+
+      x = 0;
+    }
+
+  if (x + width > area->width)
+    width = area->width - x;
+
+  if (y < 0)
+    {
+      buf1 -= y * rowstride1;
+      buf2 -= y * rowstride2;
+      mask -= y * rowstride_mask;
+      height += y;
+
+      y = 0;
+    }
+
+  if (y + height > area->height)
+    height = area->height - y;
+
+  if (! area->buf)
+    {
+      area->rowstride = ((area->width * 3) + 3) & ~3;
+      area->buf = g_new (guchar, area->rowstride * area->height);
+    }
+
+  size = 1 << (2 + area->check_size);
+  gimp_checks_get_shades (area->check_type, &light, &dark);
+
+  src1     = buf1;
+  src2     = buf2;
+  src_mask = mask;
+  dest     = area->buf + x * 3 + y * area->rowstride;
+
+  switch (type)
+    {
+    case GIMP_RGB_IMAGE:
+      for (row = 0; row < height; row++)
+        {
+          const guchar *s1 = src1;
+          const guchar *s2 = src2;
+          const guchar *m  = src_mask;
+          guchar       *d  = dest;
+
+          for (col = x; col < x + width; col++, s1 += 3, s2 += 3, m++, d+= 3)
+            {
+               d[0] = ((s1[0] << 8) + (s2[0] - s1[0]) * m[0]) >> 8;
+               d[1] = ((s1[1] << 8) + (s2[1] - s1[1]) * m[0]) >> 8;
+               d[2] = ((s1[2] << 8) + (s2[2] - s1[2]) * m[0]) >> 8;
+            }
+
+          src1     += rowstride1;
+          src2     += rowstride2;
+          src_mask += rowstride_mask;
+          dest     += area->rowstride;
+        }
+      break;
+
+    case GIMP_RGBA_IMAGE:
+       for (row = y; row < y + height; row++)
+        {
+          const guchar *s1 = src1;
+          const guchar *s2 = src2;
+          const guchar *m  = src_mask;
+          guchar       *d  = dest;
+
+          for (col = x; col < x + width; col++, s1 += 4, s2 += 4, m++, d+= 3)
+            {
+              switch (m[0])
+                {
+                case 0:
+                  switch (s1[3])
+                    {
+                    case 0:
+                      d[0] = d[1] = d[2] = CHECK_COLOR (area, row, col);
+                      break;
+
+                    case 255:
+                      d[0] = s1[0];
+                      d[1] = s1[1];
+                      d[2] = s1[2];
+                      break;
+
+                    default:
+                      {
+                        register guint alpha = s1[3] + 1;
+                        register guint check = CHECK_COLOR (area, row, col);
+
+                        d[0] = ((check << 8) + (s1[0] - check) * alpha) >> 8;
+                        d[1] = ((check << 8) + (s1[1] - check) * alpha) >> 8;
+                        d[2] = ((check << 8) + (s1[2] - check) * alpha) >> 8;
+                      }
+                      break;
+                    }
+                  break;
+
+                case 255:
+                  switch (s2[3])
+                    {
+                    case 0:
+                      d[0] = d[1] = d[2] = CHECK_COLOR (area, row, col);
+                      break;
+
+                    case 255:
+                      d[0] = s2[0];
+                      d[1] = s2[1];
+                      d[2] = s2[2];
+                      break;
+
+                    default:
+                      {
+                        register guint alpha = s2[3] + 1;
+                        register guint check = CHECK_COLOR (area, row, col);
+
+                        d[0] = ((check << 8) + (s2[0] - check) * alpha) >> 8;
+                        d[1] = ((check << 8) + (s2[1] - check) * alpha) >> 8;
+                        d[2] = ((check << 8) + (s2[2] - check) * alpha) >> 8;
+                      }
+                      break;
+                    }
+                  break;
+
+                default:
+                  {
+                    guchar inter[4];
+
+                    if (s1[3] == s2[3])
+                      {
+                        inter[0] = ((s1[0] << 8) + (s2[0] - s1[0]) * m[0]) >> 8;
+                        inter[1] = ((s1[1] << 8) + (s2[1] - s1[1]) * m[0]) >> 8;
+                        inter[2] = ((s1[2] << 8) + (s2[2] - s1[2]) * m[0]) >> 8;
+                        inter[3] = s1[3];
+                     }
+                    else
+                      {
+                        inter[3] = ((s1[3] << 8) + (s2[3] - s1[3]) * m[0]) >> 8;
+
+                        if (inter[3])
+                          {
+                            for (i = 0; i < 3; i++)
+                             {
+                               gushort a = s1[i] * s1[3];
+                               gushort b = s2[i] * s2[3];
+
+                               inter[i] =
+                                 (((a << 8) + (b  - a) * m[0]) >> 8) / inter[3];
+                             }
+                         }
+                      }
+
+                    switch (inter[3])
+                      {
+                      case 0:
+                        d[0] = d[1] = d[2] = CHECK_COLOR (area, row, col);
+                        break;
+
+                      case 255:
+                        d[0] = inter[0];
+                        d[1] = inter[1];
+                        d[2] = inter[2];
+                        break;
+
+                      default:
+                        {
+                          register guint alpha = inter[3] + 1;
+                          register guint check = CHECK_COLOR (area, row, col);
+
+                          d[0] = (((check << 8) +
+                                   (inter[0] - check) * alpha) >> 8);
+                          d[1] = (((check << 8) +
+                                   (inter[1] - check) * alpha) >> 8);
+                          d[2] = (((check << 8) +
+                                   (inter[2] - check) * alpha) >> 8);
+                        }
+                        break;
+                      }
+                  }
+                  break;
+                }
+            }
+
+          src1     += rowstride1;
+          src2     += rowstride2;
+          src_mask += rowstride_mask;
+          dest     += area->rowstride;
+        }
+       break;
+
+    case GIMP_GRAY_IMAGE:
+      for (row = 0; row < height; row++)
+        {
+          const guchar *s1 = src1;
+          const guchar *s2 = src2;
+          const guchar *m  = src_mask;
+          guchar       *d  = dest;
+
+          for (col = 0; col < width; col++, s1++, s2++, m++, d += 3)
+            d[0] = d[1] = d[2] = ((s1[0] << 8) + (s2[0] - s1[0]) * m[0]) >> 8;
+
+          src1     += rowstride1;
+          src2     += rowstride2;
+          src_mask += rowstride_mask;
+          dest     += area->rowstride;
+        }
+      break;
+
+    case GIMP_GRAYA_IMAGE:
+      for (row = y; row < y + height; row++)
+        {
+          const guchar *s1 = src1;
+          const guchar *s2 = src2;
+          const guchar *m  = src_mask;
+          guchar       *d  = dest;
+
+          for (col = x; col < x + width; col++, s1 += 2, s2 += 2, m++, d+= 3)
+            {
+              switch (m[0])
+                {
+                case 0:
+                  switch (s1[1])
+                    {
+                    case 0:
+                      d[0] = d[1] = d[2] = CHECK_COLOR (area, row, col);
+                      break;
+
+                    case 255:
+                      d[0] = d[1] = d[2] = s1[0];
+                      break;
+
+                    default:
+                      {
+                        register guint alpha = s1[1] + 1;
+                        register guint check = CHECK_COLOR (area, row, col);
+
+                        d[0] = d[1] = d[2] =
+                          ((check << 8) + (s1[0] - check) * alpha) >> 8;
+                      }
+                      break;
+                    }
+                  break;
+
+                case 255:
+                  switch (s2[1])
+                    {
+                    case 0:
+                      d[0] = d[1] = d[2] = CHECK_COLOR (area, row, col);
+                      break;
+
+                    case 255:
+                      d[0] = d[1] = d[2] = s2[0];
+                      break;
+
+                    default:
+                      {
+                        register guint alpha = s2[1] + 1;
+                        register guint check = CHECK_COLOR (area, row, col);
+
+                        d[0] = d[1] = d[2] =
+                          ((check << 8) + (s2[0] - check) * alpha) >> 8;
+                      }
+                      break;
+                    }
+                  break;
+
+                default:
+                  {
+                    guchar inter[2] = { 0, };
+
+                    if (s1[1] == s2[1])
+                      {
+                        inter[0] = ((s1[0] << 8) + (s2[0] - s1[0]) * m[0]) >> 8;
+                        inter[1] = s1[1];
+                      }
+                    else
+                      {
+                        inter[1] = ((s1[1] << 8) + (s2[1] - s1[1]) * m[0]) >> 8;
+
+                        if (inter[1])
+                          {
+                            gushort a = s1[0] * s1[1];
+                            gushort b = s2[0] * s2[1];
+
+                            inter[0] =
+                              (((a << 8) + (b  - a) * m[0]) >> 8) / inter[1];
+                          }
+                      }
+
+                    switch (inter[1])
+                      {
+                      case 0:
+                        d[0] = d[1] = d[2] = CHECK_COLOR (area, row, col);
+                        break;
+
+                      case 255:
+                        d[0] = d[1] = d[2] = inter[0];
+                        break;
+
+                      default:
+                        {
+                          register guint alpha = inter[1] + 1;
+                          register guint check = CHECK_COLOR (area, row, col);
+
+                          d[0] = d[1] = d[2] =
+                            ((check << 8) + (inter[0] - check) * alpha) >> 8;
+                        }
+                        break;
+                      }
+                  }
+                  break;
+                }
+            }
+
+          src1     += rowstride1;
+          src2     += rowstride2;
+          src_mask += rowstride_mask;
+          dest     += area->rowstride;
+        }
+      break;
+
+    case GIMP_INDEXED_IMAGE:
+      g_return_if_fail (area->colormap != NULL);
+      for (row = 0; row < height; row++)
+        {
+          const guchar *s1 = src1;
+          const guchar *s2 = src2;
+          const guchar *m  = src_mask;
+          guchar       *d  = dest;
+
+          for (col = 0; col < width; col++, s1++, s2++, m++, d += 3)
+            {
+              const guchar *cmap1 = area->colormap + 3 * s1[0];
+              const guchar *cmap2 = area->colormap + 3 * s2[0];
+
+              d[0] = ((cmap1[0] << 8) + (cmap2[0] - cmap1[0]) * m[0]) >> 8;
+              d[1] = ((cmap1[1] << 8) + (cmap2[1] - cmap1[1]) * m[0]) >> 8;
+              d[2] = ((cmap1[2] << 8) + (cmap2[2] - cmap1[2]) * m[0]) >> 8;
+            }
+
+          src1     += rowstride1;
+          src2     += rowstride2;
+          src_mask += rowstride_mask;
+          dest     += area->rowstride;
+        }
+      break;
+
+    case GIMP_INDEXEDA_IMAGE:
+      g_return_if_fail (area->colormap != NULL);
+      for (row = y; row < y + height; row++)
+        {
+          const guchar *s1 = src1;
+          const guchar *s2 = src2;
+          const guchar *m  = src_mask;
+          guchar       *d  = dest;
+
+          for (col = x; col < x + width; col++, s1 += 2, s2 += 2, m++, d += 3)
+            {
+              const guchar *cmap1  = area->colormap + 3 * s1[0];
+              const guchar *cmap2  = area->colormap + 3 * s2[0];
+
+              switch (m[0])
+                {
+                case 0:
+                  switch (s1[1])
+                    {
+                    case 0:
+                      d[0] = d[1] = d[2] = CHECK_COLOR (area, row, col);
+                      break;
+
+                    case 255:
+                      d[0] = cmap1[0];
+                      d[1] = cmap1[1];
+                      d[2] = cmap1[2];
+                      break;
+
+                    default:
+                      {
+                        register guint alpha = s1[1] + 1;
+                        register guint check = CHECK_COLOR (area, row, col);
+
+                        d[0] = ((check << 8) + (cmap1[0] - check) * alpha) >> 8;
+                        d[1] = ((check << 8) + (cmap1[1] - check) * alpha) >> 8;
+                        d[2] = ((check << 8) + (cmap1[2] - check) * alpha) >> 8;
+                      }
+                      break;
+                    }
+                  break;
+
+                case 255:
+                  switch (s2[1])
+                    {
+                    case 0:
+                      d[0] = d[1] = d[2] = CHECK_COLOR (area, row, col);
+                      break;
+
+                    case 255:
+                      d[0] = cmap2[0];
+                      d[1] = cmap2[1];
+                      d[2] = cmap2[2];
+                      break;
+
+                    default:
+                      {
+                        register guint alpha = s2[1] + 1;
+                        register guint check = CHECK_COLOR (area, row, col);
+
+                        d[0] = ((check << 8) + (cmap2[0] - check) * alpha) >> 8;
+                        d[1] = ((check << 8) + (cmap2[1] - check) * alpha) >> 8;
+                        d[2] = ((check << 8) + (cmap2[2] - check) * alpha) >> 8;
+                      }
+                      break;
+                    }
+                  break;
+
+                default:
+                  {
+                    guchar inter[4];
+
+                    if (s1[1] == s2[1])
+                      {
+                        inter[0] = (((cmap1[0] << 8) +
+                                     (cmap2[0] - cmap1[0]) * m[0]) >> 8);
+                        inter[1] = (((cmap1[1] << 8) +
+                                     (cmap2[1] - cmap1[1]) * m[0]) >> 8);
+                        inter[2] = (((cmap1[2] << 8) +
+                                     (cmap2[2] - cmap1[2]) * m[0]) >> 8);
+                        inter[3] = s1[1];
+                      }
+                    else
+                      {
+                        inter[3] = ((s1[1] << 8) + (s2[1] - s1[1]) * m[0]) >> 8;
+
+                        if (inter[3])
+                          {
+                            for (i = 0 ; i < 3 ; i++)
+                              {
+                                gushort a = cmap1[i] * s1[1];
+                                gushort b = cmap2[i] * s2[1];
+
+                                inter[i] = ((((a << 8) + (b  - a) * m[0]) >> 8)
+                                            / inter[3]);
+                              }
+                          }
+                      }
+
+                    switch (inter[3])
+                      {
+                      case 0:
+                        d[0] = d[1] = d[2] = CHECK_COLOR (area, row, col);
+                        break;
+
+                      case 255:
+                        d[0] = inter[0];
+                        d[1] = inter[1];
+                        d[2] = inter[2];
+                        break;
+
+                      default:
+                        {
+                          register guint alpha = inter[3] + 1;
+                          register guint check = CHECK_COLOR (area, row, col);
+
+                          d[0] =
+                            ((check << 8) + (inter[0] - check) * alpha) >> 8;
+                          d[1] =
+                            ((check << 8) + (inter[1] - check) * alpha) >> 8;
+                          d[2] =
+                            ((check << 8) + (inter[2] - check) * alpha) >> 8;
+                        }
+                        break;
+                      }
+                  }
+                  break;
+                }
+            }
+
+          src1     += rowstride1;
+          src2     += rowstride2;
+          src_mask += rowstride_mask;
+          dest     += area->rowstride;
+        }
+      break;
+    }
+
+  gimp_preview_area_queue_draw (area, x, y, width, height);
+}
+
+/**
+ * gimp_preview_area_fill:
+ * @area:   a #GimpPreviewArea widget.
+ * @x:      x offset in preview
+ * @y:      y offset in preview
+ * @width:  width of the rectangle to fill
+ * @height: height of the rectangle to fill
+ * @red:    red component of the fill color (0-255)
+ * @green:  green component of the fill color (0-255)
+ * @blue:   red component of the fill color (0-255)
+ *
+ * Fills the given rectangle of @area in the given color and queues a
+ * redraw.
+ *
+ * Since GIMP 2.2
+ **/
+void
+gimp_preview_area_fill (GimpPreviewArea *area,
+                        gint             x,
+                        gint             y,
+                        gint             width,
+                        gint             height,
+                        guchar           red,
+                        guchar           green,
+                        guchar           blue)
+{
+  guchar *dest;
+  guchar *d;
+  gint    row;
+  gint    col;
+
+  g_return_if_fail (GIMP_IS_PREVIEW_AREA (area));
+  g_return_if_fail (width >= 0 && height >= 0);
+
+  if (width == 0 || height == 0)
+    return;
+
+  if (x + width < 0 || x >= area->width)
+    return;
+
+  if (y + height < 0 || y >= area->height)
+    return;
+
+  if (x < 0)
+    {
+      width += x;
+      x = 0;
+    }
+
+  if (x + width > area->width)
+    width = area->width - x;
+
+  if (y < 0)
+    {
+      height += y;
+      y = 0;
+    }
+
+  if (y + height > area->height)
+    height = area->height - y;
+
+  if (! area->buf)
+    {
+      area->rowstride = ((area->width * 3) + 3) & ~3;
+      area->buf = g_new (guchar, area->rowstride * area->height);
+    }
+
+  dest = area->buf + x * 3 + y * area->rowstride;
+
+  /*  colorize first row  */
+  for (col = 0, d = dest; col < width; col++, d+= 3)
+    {
+      d[0] = red;
+      d[1] = green;
+      d[2] = blue;
+    }
+
+  /*  copy first row to remaining rows  */
+  for (row = 1, d = dest; row < height; row++)
+    {
+      d += area->rowstride;
+      memcpy (d, dest, width * 3);
+    }
+
+  gimp_preview_area_queue_draw (area, x, y, width, height);
+}
+
+/**
+ * gimp_preview_area_set_offsets:
+ * @area: a #GimpPreviewArea
+ * @x:    horizontal offset
+ * @y:    vertical offset
+ *
+ * Sets the offsets of the previewed area. This information is used
+ * when drawing the checkerboard and to determine the dither offsets.
+ *
+ * Since: 2.2
+ **/
+void
+gimp_preview_area_set_offsets (GimpPreviewArea *area,
+                               gint             x,
+                               gint             y)
+{
+  g_return_if_fail (GIMP_IS_PREVIEW_AREA (area));
+
+  area->offset_x = x;
+  area->offset_y = y;
+}
+
+/**
+ * gimp_preview_area_set_colormap:
+ * @area:       a #GimpPreviewArea
+ * @colormap:   a #guchar buffer that contains the colormap
+ * @num_colors: the number of colors in the colormap
+ *
+ * Sets the colormap for the #GimpPreviewArea widget. You need to
+ * call this function before you use gimp_preview_area_draw() with
+ * an image type of %GIMP_INDEXED_IMAGE or %GIMP_INDEXEDA_IMAGE.
+ *
+ * Since GIMP 2.2
+ **/
+void
+gimp_preview_area_set_colormap (GimpPreviewArea *area,
+                                const guchar    *colormap,
+                                gint             num_colors)
+{
+  g_return_if_fail (GIMP_IS_PREVIEW_AREA (area));
+  g_return_if_fail (colormap != NULL || num_colors == 0);
+  g_return_if_fail (num_colors >= 0 && num_colors <= 256);
+
+  if (num_colors > 0)
+    {
+      if (area->colormap)
+        memset (area->colormap, 0, 3 * 256);
+      else
+        area->colormap = g_new0 (guchar, 3 * 256);
+
+      memcpy (area->colormap, colormap, 3 * num_colors);
+    }
+  else
+    {
+      g_free (area->colormap);
+      area->colormap = NULL;
+    }
+}
+
+/**
+ * gimp_preview_area_set_color_config:
+ * @area:   a #GimpPreviewArea widget.
+ * @config: a #GimpColorConfig object.
+ *
+ * Sets the color management configuration to use with this preview area.
+ *
+ * Since: 2.10
+ */
+void
+gimp_preview_area_set_color_config (GimpPreviewArea *area,
+                                    GimpColorConfig *config)
+{
+  GimpPreviewAreaPrivate *priv;
+
+  g_return_if_fail (GIMP_IS_PREVIEW_AREA (area));
+  g_return_if_fail (config == NULL || GIMP_IS_COLOR_CONFIG (config));
+
+  priv = GET_PRIVATE (area);
+
+  if (config != priv->config)
+    {
+      if (priv->config)
+        {
+          g_signal_handlers_disconnect_by_func (priv->config,
+                                                gimp_preview_area_destroy_transform,
+                                                area);
+
+          gimp_preview_area_destroy_transform (area);
+        }
+
+      g_set_object (&priv->config, config);
+
+      if (priv->config)
+        {
+          g_signal_connect_swapped (priv->config, "notify",
+                                    G_CALLBACK (gimp_preview_area_destroy_transform),
+                                    area);
+        }
+    }
+}
+
+/**
+ * gimp_preview_area_set_max_size:
+ * @area:   a #GimpPreviewArea widget
+ * @width:  the maximum width in pixels or -1 to unset the limit
+ * @height: the maximum height in pixels or -1 to unset the limit
+ *
+ * Usually a #GimpPreviewArea fills the size that it is
+ * allocated. This function allows you to limit the preview area to a
+ * maximum size. If a larger size is allocated for the widget, the
+ * preview will draw itself centered into the allocated area.
+ *
+ * Since: 2.2
+ **/
+void
+gimp_preview_area_set_max_size (GimpPreviewArea *area,
+                                gint             width,
+                                gint             height)
+{
+  g_return_if_fail (GIMP_IS_PREVIEW_AREA (area));
+
+  area->max_width  = width;
+  area->max_height = height;
+}
+
+
+
+/*  popup menu  */
+
+static void
+gimp_preview_area_menu_toggled (GtkWidget       *item,
+                                GimpPreviewArea *area)
+{
+  gboolean active = gtk_check_menu_item_get_active (GTK_CHECK_MENU_ITEM (item));
+
+  if (active)
+    {
+      const gchar *name = g_object_get_data (G_OBJECT (item),
+                                             "gimp-preview-area-prop-name");
+      if (name)
+        {
+          gint  value =
+            GPOINTER_TO_INT (g_object_get_data (G_OBJECT (item),
+                                                "gimp-preview-area-prop-value"));
+          g_object_set (area,
+                        name, value,
+                        NULL);
+        }
+    }
+}
+
+static GtkWidget *
+gimp_preview_area_menu_new (GimpPreviewArea *area,
+                            const gchar     *property)
+{
+  GParamSpec *pspec;
+  GEnumClass *enum_class;
+  GEnumValue *enum_value;
+  GtkWidget  *menu;
+  GtkWidget  *item;
+  GSList     *group = NULL;
+  gint        value;
+
+  pspec = g_object_class_find_property (G_OBJECT_GET_CLASS (area), property);
+
+  g_return_val_if_fail (G_IS_PARAM_SPEC_ENUM (pspec), NULL);
+
+  g_object_get (area,
+                property, &value,
+                NULL);
+
+  enum_class = G_PARAM_SPEC_ENUM (pspec)->enum_class;
+
+  menu = gtk_menu_new ();
+
+  for (enum_value = enum_class->values; enum_value->value_name; enum_value++)
+    {
+      const gchar *name = gimp_enum_value_get_desc (enum_class, enum_value);
+
+      item = gtk_radio_menu_item_new_with_label (group, name);
+
+      gtk_menu_shell_append (GTK_MENU_SHELL (menu), item);
+      gtk_widget_show (item);
+
+      g_object_set_data (G_OBJECT (item),
+                         "gimp-preview-area-prop-name",
+                         (gpointer) property);
+
+      g_object_set_data (G_OBJECT (item),
+                         "gimp-preview-area-prop-value",
+                         GINT_TO_POINTER (enum_value->value));
+
+      gtk_check_menu_item_set_active (GTK_CHECK_MENU_ITEM (item),
+                                      (enum_value->value == value));
+
+      g_signal_connect (item, "toggled",
+                        G_CALLBACK (gimp_preview_area_menu_toggled),
+                        area);
+
+      group = gtk_radio_menu_item_get_group (GTK_RADIO_MENU_ITEM (item));
+    }
+
+  item = gtk_menu_item_new_with_label (g_param_spec_get_nick (pspec));
+
+  gtk_menu_item_set_submenu (GTK_MENU_ITEM (item), menu);
+
+  gtk_widget_show (item);
+
+  return item;
+}
+
+/**
+ * gimp_preview_area_menu_popup:
+ * @area:  a #GimpPreviewArea
+ * @event: the button event that causes the menu to popup or %NULL
+ *
+ * Creates a popup menu that allows one to configure the size and type of
+ * the checkerboard pattern that the @area uses to visualize transparency.
+ *
+ * Since: 2.2
+ **/
+void
+gimp_preview_area_menu_popup (GimpPreviewArea *area,
+                              GdkEventButton  *event)
+{
+  GtkWidget *menu;
+
+  g_return_if_fail (GIMP_IS_PREVIEW_AREA (area));
+
+  menu = gtk_menu_new ();
+  gtk_menu_set_screen (GTK_MENU (menu),
+                       gtk_widget_get_screen (GTK_WIDGET (area)));
+
+  gtk_menu_shell_append (GTK_MENU_SHELL (menu),
+                         gimp_preview_area_menu_new (area, "check-type"));
+  gtk_menu_shell_append (GTK_MENU_SHELL (menu),
+                         gimp_preview_area_menu_new (area, "check-size"));
+
+  if (event)
+    gtk_menu_popup (GTK_MENU (menu),
+                    NULL, NULL, NULL, NULL, event->button, event->time);
+  else
+    gtk_menu_popup (GTK_MENU (menu),
+                    NULL, NULL, NULL, NULL, 0, gtk_get_current_event_time ());
+}