[gimp] core: speed up gimp_image_contiguous_region_by_seed using a temporary GeglBuffer

[Michael Henning <mhenning src gnome org>]

commit c204b0ac413539ee763483970a64eb437a43de3f
Author: Michael Henning <drawoc darkrefraction com>
Date:   Sun Apr 7 14:27:20 2013 -0400

    core: speed up gimp_image_contiguous_region_by_seed using a temporary GeglBuffer
    
    By creating a temporary GeglBuffer of the correct format, we avoid a lot of
    babl conversions. This is about four times faster than the previous code.

 app/core/gimpimage-contiguous-region.c |   16 ++++++++++++----
 1 files changed, 12 insertions(+), 4 deletions(-)
---
diff --git a/app/core/gimpimage-contiguous-region.c b/app/core/gimpimage-contiguous-region.c
index 64edbbc..f16ba88 100644
--- a/app/core/gimpimage-contiguous-region.c
+++ b/app/core/gimpimage-contiguous-region.c
@@ -113,11 +113,10 @@ gimp_image_contiguous_region_by_seed (GimpImage           *image,
 
   src_buffer = gimp_pickable_get_buffer (pickable);
 
-  mask = gimp_channel_new_mask (image,
-                                gegl_buffer_get_width  (src_buffer),
-                                gegl_buffer_get_height (src_buffer));
+  mask_buffer = gegl_buffer_new (gegl_buffer_get_extent (src_buffer),
+                                 babl_format ("Y float"));
 
-  mask_buffer = gimp_drawable_get_buffer (GIMP_DRAWABLE (mask));
+  gegl_buffer_clear (mask_buffer, NULL);
 
   gegl_buffer_sample (src_buffer, x, y, NULL, start_col, src_format,
                       GEGL_SAMPLER_NEAREST, GEGL_ABYSS_NONE);
@@ -145,6 +144,15 @@ gimp_image_contiguous_region_by_seed (GimpImage           *image,
                                  antialias, threshold,
                                  x, y, start_col);
 
+  /* wrap mask_buffer in a drawable and return it */
+  mask = gimp_channel_new_mask (image,
+                                gegl_buffer_get_width  (mask_buffer),
+                                gegl_buffer_get_height (mask_buffer));
+
+  gimp_drawable_set_buffer (GIMP_DRAWABLE (mask), FALSE, "", mask_buffer);
+
+  g_object_unref (mask_buffer);
+
   return mask;
 }