[gimp/metadata-browser] app: pass a format, not bpp, to gimp_viewable_get_dummy_pixbuf()

[Roman Joost <romanofski src gnome org>]

commit 23db2e972ab7717a6921ffb23e9e5a2e1ebc1fdb
Author: Michael Natterer <mitch gimp org>
Date:   Sat Apr 21 21:41:36 2012 +0200

    app: pass a format, not bpp, to gimp_viewable_get_dummy_pixbuf()
    
    and add tons of <gegl.h> includes.

 app/actions/text-tool-commands.c            |    1 +
 app/core/gimp-templates.c                   |    2 +-
 app/core/gimpcurve-load.c                   |    2 +-
 app/core/gimpcurve-map.c                    |    2 +-
 app/core/gimpcurve-save.c                   |    2 +-
 app/core/gimpcurve.c                        |    2 +-
 app/core/gimpdocumentlist.c                 |    2 +-
 app/core/gimpdynamics-load.c                |    2 +-
 app/core/gimpdynamics-save.c                |    2 +-
 app/core/gimpgradient-save.c                |    2 +-
 app/core/gimpimagemapconfig.c               |    2 +-
 app/core/gimptoolpreset-save.c              |    2 +-
 app/core/gimpviewable.c                     |   37 ++++++++++-----------
 app/core/gimpviewable.h                     |    4 +-
 app/dialogs/preferences-dialog.c            |    1 +
 app/display/gimpdisplayshell-scale-dialog.c |    1 +
 app/display/gimptooldialog.c                |    1 +
 app/menus/file-menu.c                       |    1 +
 app/pdb/drawable-cmds.c                     |   47 +++++++++++++++++++--------
 app/text/gimpfontlist.c                     |    2 +-
 app/tools/gimpforegroundselecttoolundo.c    |    1 +
 app/widgets/gimpactiongroup.c               |    1 +
 app/widgets/gimpcellrendererviewable.c      |    1 +
 app/widgets/gimpcontainertreestore.c        |    1 +
 app/widgets/gimpcontainertreeview-dnd.c     |    1 +
 app/widgets/gimpcontrollerinfo.c            |    1 +
 app/widgets/gimpcontrollerlist.c            |    1 +
 app/widgets/gimpcontrollers.c               |    1 +
 app/widgets/gimpoverlaydialog.c             |    1 +
 app/widgets/gimpsettingseditor.c            |    1 +
 app/widgets/gimptemplateeditor.c            |    1 +
 app/widgets/gimpviewrenderer-frame.c        |    1 +
 app/widgets/gimpviewrendererimagefile.c     |    1 +
 tools/pdbgen/pdb/drawable.pdb               |   47 +++++++++++++++++++--------
 34 files changed, 115 insertions(+), 62 deletions(-)
---
diff --git a/app/actions/text-tool-commands.c b/app/actions/text-tool-commands.c
index 88e813b..04e364c 100644
--- a/app/actions/text-tool-commands.c
+++ b/app/actions/text-tool-commands.c
@@ -17,6 +17,7 @@
 
 #include "config.h"
 
+#include <gegl.h>
 #include <gtk/gtk.h>
 
 #include "libgimpbase/gimpbase.h"
diff --git a/app/core/gimp-templates.c b/app/core/gimp-templates.c
index 9925e0e..8da3e4e 100644
--- a/app/core/gimp-templates.c
+++ b/app/core/gimp-templates.c
@@ -19,7 +19,7 @@
 
 #include <string.h>
 
-#include <glib-object.h>
+#include <gegl.h>
 
 #include "libgimpbase/gimpbase.h"
 #include "libgimpconfig/gimpconfig.h"
diff --git a/app/core/gimpcurve-load.c b/app/core/gimpcurve-load.c
index 24c4977..4c2f32a 100644
--- a/app/core/gimpcurve-load.c
+++ b/app/core/gimpcurve-load.c
@@ -19,7 +19,7 @@
 
 #include <errno.h>
 
-#include <glib-object.h>
+#include <gegl.h>
 #include <glib/gstdio.h>
 
 #include "libgimpbase/gimpbase.h"
diff --git a/app/core/gimpcurve-map.c b/app/core/gimpcurve-map.c
index 3d02c49..81a1c9d 100644
--- a/app/core/gimpcurve-map.c
+++ b/app/core/gimpcurve-map.c
@@ -19,7 +19,7 @@
 
 #include <string.h>
 
-#include <glib-object.h>
+#include <gegl.h>
 
 #include "libgimpmath/gimpmath.h"
 
diff --git a/app/core/gimpcurve-save.c b/app/core/gimpcurve-save.c
index b7925f3..0390f37 100644
--- a/app/core/gimpcurve-save.c
+++ b/app/core/gimpcurve-save.c
@@ -19,7 +19,7 @@
 
 #include <errno.h>
 
-#include <glib-object.h>
+#include <gegl.h>
 #include <glib/gstdio.h>
 
 #include "libgimpbase/gimpbase.h"
diff --git a/app/core/gimpcurve.c b/app/core/gimpcurve.c
index 667c702..e6df335 100644
--- a/app/core/gimpcurve.c
+++ b/app/core/gimpcurve.c
@@ -20,7 +20,7 @@
 #include <stdlib.h>
 #include <string.h> /* memcmp */
 
-#include <glib-object.h>
+#include <gegl.h>
 
 #include "libgimpmath/gimpmath.h"
 #include "libgimpconfig/gimpconfig.h"
diff --git a/app/core/gimpdocumentlist.c b/app/core/gimpdocumentlist.c
index 0930009..c1da5e0 100644
--- a/app/core/gimpdocumentlist.c
+++ b/app/core/gimpdocumentlist.c
@@ -17,7 +17,7 @@
 
 #include "config.h"
 
-#include <glib-object.h>
+#include <gegl.h>
 
 #include "libgimpconfig/gimpconfig.h"
 
diff --git a/app/core/gimpdynamics-load.c b/app/core/gimpdynamics-load.c
index 19b5597..4639ad9 100644
--- a/app/core/gimpdynamics-load.c
+++ b/app/core/gimpdynamics-load.c
@@ -17,7 +17,7 @@
 
 #include "config.h"
 
-#include <glib-object.h>
+#include <gegl.h>
 
 #include "libgimpconfig/gimpconfig.h"
 
diff --git a/app/core/gimpdynamics-save.c b/app/core/gimpdynamics-save.c
index e1c222d..c316bab 100644
--- a/app/core/gimpdynamics-save.c
+++ b/app/core/gimpdynamics-save.c
@@ -17,7 +17,7 @@
 
 #include "config.h"
 
-#include <glib-object.h>
+#include <gegl.h>
 
 #include "libgimpconfig/gimpconfig.h"
 
diff --git a/app/core/gimpgradient-save.c b/app/core/gimpgradient-save.c
index 64d3f4a..5d07651 100644
--- a/app/core/gimpgradient-save.c
+++ b/app/core/gimpgradient-save.c
@@ -20,7 +20,7 @@
 #include <string.h>
 #include <errno.h>
 
-#include <glib-object.h>
+#include <gegl.h>
 #include <glib/gstdio.h>
 
 #include "libgimpbase/gimpbase.h"
diff --git a/app/core/gimpimagemapconfig.c b/app/core/gimpimagemapconfig.c
index ed64607..da2ae71 100644
--- a/app/core/gimpimagemapconfig.c
+++ b/app/core/gimpimagemapconfig.c
@@ -22,7 +22,7 @@
 
 #include <string.h>
 
-#include <glib-object.h>
+#include <gegl.h>
 
 #include "libgimpconfig/gimpconfig.h"
 
diff --git a/app/core/gimptoolpreset-save.c b/app/core/gimptoolpreset-save.c
index b2d88ba..8826ead 100644
--- a/app/core/gimptoolpreset-save.c
+++ b/app/core/gimptoolpreset-save.c
@@ -17,7 +17,7 @@
 
 #include "config.h"
 
-#include <glib-object.h>
+#include <gegl.h>
 
 #include "libgimpconfig/gimpconfig.h"
 
diff --git a/app/core/gimpviewable.c b/app/core/gimpviewable.c
index 3b81bc7..dfeaba7 100644
--- a/app/core/gimpviewable.c
+++ b/app/core/gimpviewable.c
@@ -794,35 +794,33 @@ gimp_viewable_get_new_preview (GimpViewable *viewable,
  * Returns: a #GimpTempBuf containing the preview image.
  **/
 GimpTempBuf *
-gimp_viewable_get_dummy_preview (GimpViewable  *viewable,
-                                 gint           width,
-                                 gint           height,
-                                 gint           bpp)
+gimp_viewable_get_dummy_preview (GimpViewable *viewable,
+                                 gint          width,
+                                 gint          height,
+                                 const Babl   *format)
 {
   GdkPixbuf   *pixbuf;
   GimpTempBuf *buf;
-  guchar      *src;
-  guchar      *dest;
+  GeglBuffer  *src_buffer;
+  GeglBuffer  *dest_buffer;
 
   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 (bpp == 3 || bpp == 4, NULL);
+  g_return_val_if_fail (format != NULL, NULL);
 
-  pixbuf = gimp_viewable_get_dummy_pixbuf (viewable, width, height, bpp);
+  pixbuf = gimp_viewable_get_dummy_pixbuf (viewable, width, height,
+                                           babl_format_has_alpha (format));
 
-  buf = gimp_temp_buf_new (width, height, gimp_bpp_to_babl_format (bpp));
+  buf = gimp_temp_buf_new (width, height, format);
 
-  src  = gdk_pixbuf_get_pixels (pixbuf);
-  dest = gimp_temp_buf_get_data (buf);
+  src_buffer  = gimp_pixbuf_create_buffer (pixbuf);
+  dest_buffer = gimp_temp_buf_create_buffer (buf);
 
-  while (height--)
-    {
-      memcpy (dest, src, width * bpp);
+  gegl_buffer_copy (src_buffer, NULL, dest_buffer, NULL);
 
-      src  += gdk_pixbuf_get_rowstride (pixbuf);
-      dest += width * bpp;
-    }
+  g_object_unref (src_buffer);
+  g_object_unref (dest_buffer);
 
   g_object_unref (pixbuf);
 
@@ -968,7 +966,7 @@ GdkPixbuf *
 gimp_viewable_get_dummy_pixbuf (GimpViewable  *viewable,
                                 gint           width,
                                 gint           height,
-                                gint           bpp)
+                                gboolean       with_alpha)
 {
   GdkPixbuf *icon;
   GdkPixbuf *pixbuf;
@@ -978,7 +976,6 @@ gimp_viewable_get_dummy_pixbuf (GimpViewable  *viewable,
   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 (bpp == 3 || bpp == 4, NULL);
 
   icon = gdk_pixbuf_new_from_inline (-1, stock_question_64, FALSE, NULL);
 
@@ -993,7 +990,7 @@ gimp_viewable_get_dummy_pixbuf (GimpViewable  *viewable,
   w = RINT (ratio * (gdouble) w);
   h = RINT (ratio * (gdouble) h);
 
-  pixbuf = gdk_pixbuf_new (GDK_COLORSPACE_RGB, (bpp == 4), 8, width, height);
+  pixbuf = gdk_pixbuf_new (GDK_COLORSPACE_RGB, with_alpha, 8, width, height);
   gdk_pixbuf_fill (pixbuf, 0xffffffff);
 
   if (w && h)
diff --git a/app/core/gimpviewable.h b/app/core/gimpviewable.h
index 9af188f..49e2922 100644
--- a/app/core/gimpviewable.h
+++ b/app/core/gimpviewable.h
@@ -148,7 +148,7 @@ GimpTempBuf   * gimp_viewable_get_new_preview    (GimpViewable  *viewable,
 GimpTempBuf   * gimp_viewable_get_dummy_preview  (GimpViewable  *viewable,
                                                   gint           width,
                                                   gint           height,
-                                                  gint           bpp);
+                                                  const Babl    *format);
 
 GdkPixbuf     * gimp_viewable_get_pixbuf         (GimpViewable  *viewable,
                                                   GimpContext   *context,
@@ -162,7 +162,7 @@ GdkPixbuf     * gimp_viewable_get_new_pixbuf     (GimpViewable  *viewable,
 GdkPixbuf     * gimp_viewable_get_dummy_pixbuf   (GimpViewable  *viewable,
                                                   gint           width,
                                                   gint           height,
-                                                  gint           bpp);
+                                                  gboolean       with_alpha);
 
 gchar         * gimp_viewable_get_description    (GimpViewable  *viewable,
                                                   gchar        **tooltip);
diff --git a/app/dialogs/preferences-dialog.c b/app/dialogs/preferences-dialog.c
index a8e6d5b..5a6e444 100644
--- a/app/dialogs/preferences-dialog.c
+++ b/app/dialogs/preferences-dialog.c
@@ -19,6 +19,7 @@
 
 #include <string.h>
 
+#include <gegl.h>
 #include <gtk/gtk.h>
 
 #include "libgimpmath/gimpmath.h"
diff --git a/app/display/gimpdisplayshell-scale-dialog.c b/app/display/gimpdisplayshell-scale-dialog.c
index f4c269e..7ec5f21 100644
--- a/app/display/gimpdisplayshell-scale-dialog.c
+++ b/app/display/gimpdisplayshell-scale-dialog.c
@@ -17,6 +17,7 @@
 
 #include "config.h"
 
+#include <gegl.h>
 #include <gtk/gtk.h>
 
 #include "libgimpmath/gimpmath.h"
diff --git a/app/display/gimptooldialog.c b/app/display/gimptooldialog.c
index 71181ea..f31b301 100644
--- a/app/display/gimptooldialog.c
+++ b/app/display/gimptooldialog.c
@@ -20,6 +20,7 @@
 
 #include "config.h"
 
+#include <gegl.h>
 #include <gtk/gtk.h>
 
 #include "libgimpwidgets/gimpwidgets.h"
diff --git a/app/menus/file-menu.c b/app/menus/file-menu.c
index b949850..9b0b6e4 100644
--- a/app/menus/file-menu.c
+++ b/app/menus/file-menu.c
@@ -17,6 +17,7 @@
 
 #include "config.h"
 
+#include <gegl.h>
 #include <gtk/gtk.h>
 
 #include "libgimpthumb/gimpthumb.h"
diff --git a/app/pdb/drawable-cmds.c b/app/pdb/drawable-cmds.c
index 8206bd8..3a5a1a6 100644
--- a/app/pdb/drawable-cmds.c
+++ b/app/pdb/drawable-cmds.c
@@ -735,13 +735,22 @@ drawable_thumbnail_invoker (GimpProcedure      *procedure,
         width  = MAX (1, (height * dwidth) / dheight);
 
       if (image->gimp->config->layer_previews)
-        buf = gimp_viewable_get_new_preview (GIMP_VIEWABLE (drawable), context,
-                                             width, height);
+        {
+          buf = gimp_viewable_get_new_preview (GIMP_VIEWABLE (drawable), context,
+                                               width, height);
+        }
       else
-        buf = gimp_viewable_get_dummy_preview (GIMP_VIEWABLE (drawable),
-                                               width, height,
-                                               gimp_drawable_has_alpha (drawable) ?
-                                               4 : 3);
+        {
+          const Babl *format;
+
+          if (gimp_drawable_has_alpha (drawable))
+            format = babl_format ("R'G'B'A u8");
+          else
+            format = babl_format ("R'G'B' u8");
+
+          buf = gimp_viewable_get_dummy_preview (GIMP_VIEWABLE (drawable),
+                                                 width, height, format);
+        }
 
       if (buf)
         {
@@ -813,15 +822,25 @@ drawable_sub_thumbnail_invoker (GimpProcedure      *procedure,
           GimpTempBuf *buf;
 
           if (image->gimp->config->layer_previews)
-            buf = gimp_drawable_get_sub_preview (drawable,
-                                                 src_x, src_y,
-                                                 src_width, src_height,
-                                                 dest_width, dest_height);
+            {
+              buf = gimp_drawable_get_sub_preview (drawable,
+                                                   src_x, src_y,
+                                                   src_width, src_height,
+                                                   dest_width, dest_height);
+            }
           else
-            buf = gimp_viewable_get_dummy_preview (GIMP_VIEWABLE (drawable),
-                                                   dest_width, dest_height,
-                                                   gimp_drawable_has_alpha (drawable) ?
-                                                   4 : 3);
+            {
+              const Babl *format;
+
+              if (gimp_drawable_has_alpha (drawable))
+                format = babl_format ("R'G'B'A u8");
+              else
+                format = babl_format ("R'G'B' u8");
+
+              buf = gimp_viewable_get_dummy_preview (GIMP_VIEWABLE (drawable),
+                                                     dest_width, dest_height,
+                                                     format);
+            }
 
           if (buf)
             {
diff --git a/app/text/gimpfontlist.c b/app/text/gimpfontlist.c
index a89adde..b812a31 100644
--- a/app/text/gimpfontlist.c
+++ b/app/text/gimpfontlist.c
@@ -24,7 +24,7 @@
 
 #include <string.h>
 
-#include <glib-object.h>
+#include <gegl.h>
 #include <pango/pangocairo.h>
 #include <pango/pangofc-fontmap.h>
 
diff --git a/app/tools/gimpforegroundselecttoolundo.c b/app/tools/gimpforegroundselecttoolundo.c
index d91fb70..a735f7d 100644
--- a/app/tools/gimpforegroundselecttoolundo.c
+++ b/app/tools/gimpforegroundselecttoolundo.c
@@ -17,6 +17,7 @@
 
 #include "config.h"
 
+#include <gegl.h>
 #include <gtk/gtk.h>
 
 #include "tools-types.h"
diff --git a/app/widgets/gimpactiongroup.c b/app/widgets/gimpactiongroup.c
index a399c4b..85b1900 100644
--- a/app/widgets/gimpactiongroup.c
+++ b/app/widgets/gimpactiongroup.c
@@ -20,6 +20,7 @@
 
 #include "config.h"
 
+#include <gegl.h>
 #include <gtk/gtk.h>
 
 #include "libgimpbase/gimpbase.h"
diff --git a/app/widgets/gimpcellrendererviewable.c b/app/widgets/gimpcellrendererviewable.c
index c490b19..2115f08 100644
--- a/app/widgets/gimpcellrendererviewable.c
+++ b/app/widgets/gimpcellrendererviewable.c
@@ -20,6 +20,7 @@
 
 #include <config.h>
 
+#include <gegl.h>
 #include <gtk/gtk.h>
 
 #include "widgets-types.h"
diff --git a/app/widgets/gimpcontainertreestore.c b/app/widgets/gimpcontainertreestore.c
index 16b43b8..05ae500 100644
--- a/app/widgets/gimpcontainertreestore.c
+++ b/app/widgets/gimpcontainertreestore.c
@@ -22,6 +22,7 @@
 
 #include <string.h>
 
+#include <gegl.h>
 #include <gtk/gtk.h>
 
 #include "widgets-types.h"
diff --git a/app/widgets/gimpcontainertreeview-dnd.c b/app/widgets/gimpcontainertreeview-dnd.c
index 91367e6..85fa472 100644
--- a/app/widgets/gimpcontainertreeview-dnd.c
+++ b/app/widgets/gimpcontainertreeview-dnd.c
@@ -20,6 +20,7 @@
 
 #include "config.h"
 
+#include <gegl.h>
 #include <gtk/gtk.h>
 
 #include "widgets-types.h"
diff --git a/app/widgets/gimpcontrollerinfo.c b/app/widgets/gimpcontrollerinfo.c
index 90e70c9..057ba09 100644
--- a/app/widgets/gimpcontrollerinfo.c
+++ b/app/widgets/gimpcontrollerinfo.c
@@ -22,6 +22,7 @@
 
 #include <string.h>
 
+#include <gegl.h>
 #include <gtk/gtk.h>
 
 #include "libgimpconfig/gimpconfig.h"
diff --git a/app/widgets/gimpcontrollerlist.c b/app/widgets/gimpcontrollerlist.c
index d4896ac..f87d798 100644
--- a/app/widgets/gimpcontrollerlist.c
+++ b/app/widgets/gimpcontrollerlist.c
@@ -22,6 +22,7 @@
 
 #include <string.h>
 
+#include <gegl.h>
 #include <gtk/gtk.h>
 
 #include "libgimpwidgets/gimpwidgets.h"
diff --git a/app/widgets/gimpcontrollers.c b/app/widgets/gimpcontrollers.c
index 4d43cb2..8c5877f 100644
--- a/app/widgets/gimpcontrollers.c
+++ b/app/widgets/gimpcontrollers.c
@@ -17,6 +17,7 @@
 
 #include "config.h"
 
+#include <gegl.h>
 #include <gtk/gtk.h>
 
 #include "libgimpbase/gimpbase.h"
diff --git a/app/widgets/gimpoverlaydialog.c b/app/widgets/gimpoverlaydialog.c
index 063426b..8031dcc 100644
--- a/app/widgets/gimpoverlaydialog.c
+++ b/app/widgets/gimpoverlaydialog.c
@@ -20,6 +20,7 @@
 
 #include "config.h"
 
+#include <gegl.h>
 #include <gtk/gtk.h>
 #include <gdk/gdkkeysyms.h>
 
diff --git a/app/widgets/gimpsettingseditor.c b/app/widgets/gimpsettingseditor.c
index a554e86..3710917 100644
--- a/app/widgets/gimpsettingseditor.c
+++ b/app/widgets/gimpsettingseditor.c
@@ -22,6 +22,7 @@
 
 #include <string.h>
 
+#include <gegl.h>
 #include <gtk/gtk.h>
 
 #include "libgimpbase/gimpbase.h"
diff --git a/app/widgets/gimptemplateeditor.c b/app/widgets/gimptemplateeditor.c
index 53166c0..075deb2 100644
--- a/app/widgets/gimptemplateeditor.c
+++ b/app/widgets/gimptemplateeditor.c
@@ -19,6 +19,7 @@
 
 #include <string.h>
 
+#include <gegl.h>
 #include <gtk/gtk.h>
 
 #include "libgimpmath/gimpmath.h"
diff --git a/app/widgets/gimpviewrenderer-frame.c b/app/widgets/gimpviewrenderer-frame.c
index 0eb1547..9e7b335 100644
--- a/app/widgets/gimpviewrenderer-frame.c
+++ b/app/widgets/gimpviewrenderer-frame.c
@@ -22,6 +22,7 @@
 
 #include "config.h"
 
+#include <gegl.h>
 #include <gtk/gtk.h>
 
 #include "libgimpwidgets/gimpwidgets.h"
diff --git a/app/widgets/gimpviewrendererimagefile.c b/app/widgets/gimpviewrendererimagefile.c
index 60bcbf1..2a9c7d2 100644
--- a/app/widgets/gimpviewrendererimagefile.c
+++ b/app/widgets/gimpviewrendererimagefile.c
@@ -22,6 +22,7 @@
 
 #include <string.h>
 
+#include <gegl.h>
 #include <gtk/gtk.h>
 
 #include "libgimpthumb/gimpthumb.h"
diff --git a/tools/pdbgen/pdb/drawable.pdb b/tools/pdbgen/pdb/drawable.pdb
index 7cc6946..ced571a 100644
--- a/tools/pdbgen/pdb/drawable.pdb
+++ b/tools/pdbgen/pdb/drawable.pdb
@@ -719,13 +719,22 @@ HELP
     width  = MAX (1, (height * dwidth) / dheight);
 
   if (image->gimp->config->layer_previews)
-    buf = gimp_viewable_get_new_preview (GIMP_VIEWABLE (drawable), context,
-                                         width, height);
+    {
+      buf = gimp_viewable_get_new_preview (GIMP_VIEWABLE (drawable), context,
+                                           width, height);
+    }
   else
-    buf = gimp_viewable_get_dummy_preview (GIMP_VIEWABLE (drawable),
-                                           width, height,
-                                           gimp_drawable_has_alpha (drawable) ?
-                                           4 : 3);
+    {
+      const Babl *format;
+
+      if (gimp_drawable_has_alpha (drawable))
+        format = babl_format ("R'G'B'A u8");
+      else
+        format = babl_format ("R'G'B' u8");
+
+      buf = gimp_viewable_get_dummy_preview (GIMP_VIEWABLE (drawable),
+                                             width, height, format);
+    }
 
   if (buf)
     {
@@ -798,15 +807,25 @@ HELP
       GimpTempBuf *buf;
 
       if (image->gimp->config->layer_previews)
-        buf = gimp_drawable_get_sub_preview (drawable,
-                                             src_x, src_y,
-                                             src_width, src_height,
-                                             dest_width, dest_height);
+        {
+          buf = gimp_drawable_get_sub_preview (drawable,
+                                               src_x, src_y,
+                                               src_width, src_height,
+                                               dest_width, dest_height);
+        }
       else
-        buf = gimp_viewable_get_dummy_preview (GIMP_VIEWABLE (drawable),
-                                               dest_width, dest_height,
-                                               gimp_drawable_has_alpha (drawable) ?
-                                               4 : 3);
+        {
+          const Babl *format;
+
+          if (gimp_drawable_has_alpha (drawable))
+            format = babl_format ("R'G'B'A u8");
+          else
+            format = babl_format ("R'G'B' u8");
+
+          buf = gimp_viewable_get_dummy_preview (GIMP_VIEWABLE (drawable),
+                                                 dest_width, dest_height,
+                                                 format);
+        }
 
       if (buf)
         {