[gimp/gimp-2-8] app: return a GError when flattening the image failed

[Simon Budig <simon src gnome org>]

commit 1ecc25a260aac95344c984e4014e429812cafec3
Author: Michael Natterer <mitch gimp org>
Date:   Fri Aug 9 21:31:55 2013 +0200

    app: return a GError when flattening the image failed
    
    (cherry picked from commit c32c1208b09c3383435fd038a3bd21932d663a47)

 app/actions/image-commands.c |   13 ++++++++++++-
 app/core/gimpimage-merge.c   |   12 +++++++++---
 app/core/gimpimage-merge.h   |    3 ++-
 app/pdb/image-cmds.c         |    2 +-
 tools/pdbgen/pdb/image.pdb   |    2 +-
 5 files changed, 25 insertions(+), 7 deletions(-)
---
diff --git a/app/actions/image-commands.c b/app/actions/image-commands.c
index 2526b1e..3b45ac8 100644
--- a/app/actions/image-commands.c
+++ b/app/actions/image-commands.c
@@ -487,9 +487,20 @@ image_flatten_image_cmd_callback (GtkAction *action,
                                   gpointer   data)
 {
   GimpImage *image;
+  GtkWidget *widget;
+  GError    *error = NULL;
   return_if_no_image (image, data);
+  return_if_no_widget (widget, data);
+
+  if (! gimp_image_flatten (image, action_data_get_context (data), &error))
+    {
+      gimp_message_literal (image->gimp,
+                            G_OBJECT (widget), GIMP_MESSAGE_WARNING,
+                            error->message);
+      g_clear_error (&error);
+      return;
+    }
 
-  gimp_image_flatten (image, action_data_get_context (data));
   gimp_image_flush (image);
 }
 
diff --git a/app/core/gimpimage-merge.c b/app/core/gimpimage-merge.c
index 5038c93..effde79 100644
--- a/app/core/gimpimage-merge.c
+++ b/app/core/gimpimage-merge.c
@@ -161,8 +161,9 @@ gimp_image_merge_visible_layers (GimpImage     *image,
 }
 
 GimpLayer *
-gimp_image_flatten (GimpImage   *image,
-                    GimpContext *context)
+gimp_image_flatten (GimpImage    *image,
+                    GimpContext  *context,
+                    GError      **error)
 {
   GList     *list;
   GSList    *merge_list = NULL;
@@ -170,6 +171,7 @@ gimp_image_flatten (GimpImage   *image,
 
   g_return_val_if_fail (GIMP_IS_IMAGE (image), NULL);
   g_return_val_if_fail (GIMP_IS_CONTEXT (context), NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, NULL);
 
   for (list = gimp_image_get_layer_iter (image);
        list;
@@ -207,9 +209,13 @@ gimp_image_flatten (GimpImage   *image,
       gimp_image_undo_group_end (image);
 
       gimp_unset_busy (image->gimp);
+
+      return layer;
     }
 
-  return gimp_image_get_active_layer (image);
+  g_set_error_literal (error, GIMP_ERROR, GIMP_FAILED,
+                       _("Cannot flatten an image without any visible layer."));
+  return NULL;
 }
 
 GimpLayer *
diff --git a/app/core/gimpimage-merge.h b/app/core/gimpimage-merge.h
index 35bdce1..f5031ef 100644
--- a/app/core/gimpimage-merge.h
+++ b/app/core/gimpimage-merge.h
@@ -33,7 +33,8 @@ GimpLayer   * gimp_image_merge_group_layer     (GimpImage      *image,
                                                 GimpGroupLayer *group);
 
 GimpLayer   * gimp_image_flatten               (GimpImage      *image,
-                                                GimpContext    *context);
+                                                GimpContext    *context,
+                                                GError        **error);
 
 GimpVectors * gimp_image_merge_visible_vectors (GimpImage      *image,
                                                 GError        **error);
diff --git a/app/pdb/image-cmds.c b/app/pdb/image-cmds.c
index 942e026..5c194a3 100644
--- a/app/pdb/image-cmds.c
+++ b/app/pdb/image-cmds.c
@@ -1404,7 +1404,7 @@ image_flatten_invoker (GimpProcedure      *procedure,
 
   if (success)
     {
-      layer = gimp_image_flatten (image, context);
+      layer = gimp_image_flatten (image, context, error);
 
       if (! layer)
         success = FALSE;
diff --git a/tools/pdbgen/pdb/image.pdb b/tools/pdbgen/pdb/image.pdb
index a84aea3..aca9e67 100644
--- a/tools/pdbgen/pdb/image.pdb
+++ b/tools/pdbgen/pdb/image.pdb
@@ -1028,7 +1028,7 @@ HELP
         headers => [ qw("core/gimpimage-merge.h") ],
         code => <<'CODE'
 {
-  layer = gimp_image_flatten (image, context);
+  layer = gimp_image_flatten (image, context, error);
 
   if (! layer)
     success = FALSE;