[gimp/gimp-2-10] app: add GimpDrawable::format-changed signal

[Ell <ell src gnome org>]

commit 7c1d5b7a3edc90bbfb92bc210c4035938dfe13e4
Author: Ell <ell_se yahoo com>
Date:   Fri Dec 28 02:06:40 2018 -0500

    app: add GimpDrawable::format-changed signal
    
    ... which is emitted when the drawable's format is changed.
    
    (cherry picked from commit 85e454bae800f216e5e47c4be5b9f6e99b9b505a)

 app/core/gimpdrawable.c | 47 ++++++++++++++++++++++++++++++++++++-----------
 app/core/gimpdrawable.h |  2 +-
 2 files changed, 37 insertions(+), 12 deletions(-)
---
diff --git a/app/core/gimpdrawable.c b/app/core/gimpdrawable.c
index b2d7e24fe6..1d9e07eaac 100644
--- a/app/core/gimpdrawable.c
+++ b/app/core/gimpdrawable.c
@@ -66,6 +66,7 @@
 enum
 {
   UPDATE,
+  FORMAT_CHANGED,
   ALPHA_CHANGED,
   LAST_SIGNAL
 };
@@ -196,6 +197,9 @@ static void       gimp_drawable_real_swap_pixels   (GimpDrawable      *drawable,
                                                     gint               y);
 static GeglNode * gimp_drawable_real_get_source_node (GimpDrawable    *drawable);
 
+static void       gimp_drawable_format_changed     (GimpDrawable      *drawable);
+static void       gimp_drawable_alpha_changed      (GimpDrawable      *drawable);
+
 
 G_DEFINE_TYPE_WITH_CODE (GimpDrawable, gimp_drawable, GIMP_TYPE_ITEM,
                          G_ADD_PRIVATE (GimpDrawable)
@@ -231,6 +235,15 @@ gimp_drawable_class_init (GimpDrawableClass *klass)
                   G_TYPE_INT,
                   G_TYPE_INT);
 
+  gimp_drawable_signals[FORMAT_CHANGED] =
+    g_signal_new ("format-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpDrawableClass, format_changed),
+                  NULL, NULL,
+                  gimp_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
   gimp_drawable_signals[ALPHA_CHANGED] =
     g_signal_new ("alpha-changed",
                   G_TYPE_FROM_CLASS (klass),
@@ -262,6 +275,7 @@ gimp_drawable_class_init (GimpDrawableClass *klass)
   item_class->transform           = gimp_drawable_transform;
 
   klass->update                   = gimp_drawable_real_update;
+  klass->format_changed           = NULL;
   klass->alpha_changed            = NULL;
   klass->estimate_memsize         = gimp_drawable_real_estimate_memsize;
   klass->invalidate_boundary      = NULL;
@@ -801,8 +815,9 @@ gimp_drawable_real_set_buffer (GimpDrawable *drawable,
                                gint          offset_x,
                                gint          offset_y)
 {
-  GimpItem *item          = GIMP_ITEM (drawable);
-  gint      old_has_alpha = -1;
+  GimpItem   *item          = GIMP_ITEM (drawable);
+  const Babl *old_format    = NULL;
+  gint        old_has_alpha = -1;
 
   g_object_freeze_notify (G_OBJECT (drawable));
 
@@ -813,7 +828,10 @@ gimp_drawable_real_set_buffer (GimpDrawable *drawable,
                                        drawable, FALSE);
 
   if (drawable->private->buffer)
-    old_has_alpha = gimp_drawable_has_alpha (drawable);
+    {
+      old_format    = gimp_drawable_get_format (drawable);
+      old_has_alpha = gimp_drawable_has_alpha (drawable);
+    }
 
   g_set_object (&drawable->private->buffer, buffer);
 
@@ -842,6 +860,9 @@ gimp_drawable_real_set_buffer (GimpDrawable *drawable,
                       gegl_buffer_get_width  (buffer),
                       gegl_buffer_get_height (buffer));
 
+  if (gimp_drawable_get_format (drawable) != old_format)
+    gimp_drawable_format_changed (drawable);
+
   if (gimp_drawable_has_alpha (drawable) != old_has_alpha)
     gimp_drawable_alpha_changed (drawable);
 
@@ -939,6 +960,18 @@ gimp_drawable_real_get_source_node (GimpDrawable *drawable)
   return g_object_ref (drawable->private->buffer_source_node);
 }
 
+static void
+gimp_drawable_format_changed (GimpDrawable *drawable)
+{
+  g_signal_emit (drawable, gimp_drawable_signals[FORMAT_CHANGED], 0);
+}
+
+static void
+gimp_drawable_alpha_changed (GimpDrawable *drawable)
+{
+  g_signal_emit (drawable, gimp_drawable_signals[ALPHA_CHANGED], 0);
+}
+
 
 /*  public functions  */
 
@@ -1056,14 +1089,6 @@ gimp_drawable_update (GimpDrawable *drawable,
     }
 }
 
-void
-gimp_drawable_alpha_changed (GimpDrawable *drawable)
-{
-  g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
-
-  g_signal_emit (drawable, gimp_drawable_signals[ALPHA_CHANGED], 0);
-}
-
 void
 gimp_drawable_invalidate_boundary (GimpDrawable *drawable)
 {
diff --git a/app/core/gimpdrawable.h b/app/core/gimpdrawable.h
index a36f001c17..571cf20a4b 100644
--- a/app/core/gimpdrawable.h
+++ b/app/core/gimpdrawable.h
@@ -50,6 +50,7 @@ struct _GimpDrawableClass
                                            gint                  y,
                                            gint                  width,
                                            gint                  height);
+  void          (* format_changed)        (GimpDrawable         *drawable);
   void          (* alpha_changed)         (GimpDrawable         *drawable);
 
   /*  virtual functions  */
@@ -135,7 +136,6 @@ void            gimp_drawable_update             (GimpDrawable       *drawable,
                                                   gint                y,
                                                   gint                width,
                                                   gint                height);
-void            gimp_drawable_alpha_changed      (GimpDrawable       *drawable);
 
 void           gimp_drawable_invalidate_boundary (GimpDrawable       *drawable);
 void         gimp_drawable_get_active_components (GimpDrawable       *drawable,