[gimp] app: use gimp_image_get_component_format() instead of hardcoding "A u8"

[Michael Natterer <mitch src gnome org>]

commit 7c271f15fcf3dcb5a5da02cf8eb39e1756d8d9d0
Author: Michael Natterer <mitch gimp org>
Date:   Sun Apr 22 15:50:02 2012 +0200

    app: use gimp_image_get_component_format() instead of hardcoding "A u8"
    
    to extract a drawable's alpha channel into a layer mask.

 app/core/gimplayer.c |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)
---
diff --git a/app/core/gimplayer.c b/app/core/gimplayer.c
index 29c350b..f4ffefa 100644
--- a/app/core/gimplayer.c
+++ b/app/core/gimplayer.c
@@ -1292,10 +1292,14 @@ gimp_layer_create_mask (const GimpLayer *layer,
       if (gimp_drawable_has_alpha (drawable))
         {
           GeglBuffer *dest_buffer;
+          const Babl *component_format;
 
           dest_buffer = gimp_drawable_get_buffer (GIMP_DRAWABLE (mask));
 
-          gegl_buffer_set_format (dest_buffer, babl_format ("A u8"));
+          component_format =
+            gimp_image_get_component_format (image, GIMP_ALPHA_CHANNEL);
+
+          gegl_buffer_set_format (dest_buffer, component_format);
           gegl_buffer_copy (gimp_drawable_get_buffer (drawable), NULL,
                             dest_buffer, NULL);
           gegl_buffer_set_format (dest_buffer, NULL);