[gimp] app: don't show result-size warning when transforming a selection

[Ell <ell src gnome org>]

commit 1c91578bb29b6fadd7973a97e5e38218cfd111d4
Author: Ell <ell_se yahoo com>
Date:   Tue May 21 08:12:04 2019 -0400

    app: don't show result-size warning when transforming a selection
    
    In gimp_drawable_transform_get_effective_clip(), always return
    RESIZE_CLIP when the input drawable is the image mask, since the
    presence of a selection doesn't matter in this case.  This avoids
    erroneously displaying a result-size warning when transforming the
    selection using any of the selection tools.

 app/core/gimpdrawable-transform.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)
---
diff --git a/app/core/gimpdrawable-transform.c b/app/core/gimpdrawable-transform.c
index a18d95cafc..b5c1743a2e 100644
--- a/app/core/gimpdrawable-transform.c
+++ b/app/core/gimpdrawable-transform.c
@@ -85,10 +85,14 @@ gimp_drawable_transform_get_effective_clip (GimpDrawable        *drawable,
         }
       else
         {
-          GimpImage *image = gimp_item_get_image (GIMP_ITEM (drawable));
+          GimpImage   *image = gimp_item_get_image (GIMP_ITEM (drawable));
+          GimpChannel *mask  = gimp_image_get_mask (image);
 
-          if (gimp_channel_is_empty (gimp_image_get_mask (image)))
-            clip_result = GIMP_TRANSFORM_RESIZE_CLIP;
+          if (GIMP_CHANNEL (drawable) == mask ||
+              gimp_channel_is_empty (mask))
+            {
+              clip_result = GIMP_TRANSFORM_RESIZE_CLIP;
+            }
         }
     }