app: replace GimpProjectable::get_image_type() by ::get_format()

and change semantics to returning the format it wants to be projected
in, not its actual format.

app/core/gimpgrouplayer.c

@@ -140,6 +140,7 @@ static void            gimp_group_layer_convert_type (GimpDrawable      *drawabl
                                                       GimpImageBaseType  new_base_type,
                                                       gboolean           push_undo);
 
+static const Babl    * gimp_group_layer_get_format   (GimpProjectable *projectable);
 static GeglNode      * gimp_group_layer_get_graph    (GimpProjectable *projectable);
 static GList         * gimp_group_layer_get_layers   (GimpProjectable *projectable);
 static gint            gimp_group_layer_get_opacity_at
@@ -237,7 +238,7 @@ static void
 gimp_projectable_iface_init (GimpProjectableInterface *iface)
 {
   iface->get_image          = (GimpImage * (*) (GimpProjectable *)) gimp_item_get_image;
-  iface->get_image_type     = (GimpImageType (*) (GimpProjectable *)) gimp_drawable_type;
+  iface->get_format         = gimp_group_layer_get_format;
   iface->get_offset         = (void (*) (GimpProjectable*, gint*, gint*)) gimp_item_get_offset;
   iface->get_size           = (void (*) (GimpProjectable*, gint*, gint*)) gimp_viewable_get_size;
   iface->get_graph          = gimp_group_layer_get_graph;
@@ -871,6 +872,26 @@ gimp_group_layer_convert_type (GimpDrawable      *drawable,
   g_object_unref (buffer);
 }
 
+static const Babl *
+gimp_group_layer_get_format (GimpProjectable *projectable)
+{
+  GimpDrawable *drawable = GIMP_DRAWABLE (projectable);
+
+  switch (GIMP_IMAGE_TYPE_BASE_TYPE (gimp_drawable_type (drawable)))
+    {
+    case GIMP_RGB:
+    case GIMP_INDEXED:
+      return babl_format ("R'G'B'A u8");
+
+    case GIMP_GRAY:
+      return babl_format ("Y'A u8");
+    }
+
+  g_assert_not_reached ();
+
+  return NULL;
+}
+
 static GeglNode *
 gimp_group_layer_get_graph (GimpProjectable *projectable)
 {

app/core/gimpimage.c

@@ -175,9 +175,9 @@ static const guint8 * gimp_image_get_icc_profile (GimpColorManaged  *managed,
 
 static void        gimp_image_projectable_flush  (GimpProjectable   *projectable,
                                                   gboolean           invalidate_preview);
-static GeglNode     * gimp_image_get_graph       (GimpProjectable   *projectable);
+static GeglNode   * gimp_image_get_graph         (GimpProjectable   *projectable);
-static GimpImage    * gimp_image_get_image       (GimpProjectable   *projectable);
+static GimpImage  * gimp_image_get_image         (GimpProjectable   *projectable);
-static GimpImageType  gimp_image_get_image_type  (GimpProjectable   *projectable);
+static const Babl * gimp_image_get_proj_format   (GimpProjectable   *projectable);
 
 static void     gimp_image_mask_update           (GimpDrawable      *drawable,
                                                   gint               x,
@@ -609,7 +609,7 @@ gimp_projectable_iface_init (GimpProjectableInterface *iface)
 {
   iface->flush              = gimp_image_projectable_flush;
   iface->get_image          = gimp_image_get_image;
-  iface->get_image_type     = gimp_image_get_image_type;
+  iface->get_format         = gimp_image_get_proj_format;
   iface->get_size           = (void (*) (GimpProjectable*, gint*, gint*)) gimp_image_get_size;
   iface->get_graph          = gimp_image_get_graph;
   iface->invalidate_preview = (void (*) (GimpProjectable*)) gimp_viewable_invalidate_preview;
@@ -1265,15 +1265,24 @@ gimp_image_get_image (GimpProjectable *projectable)
   return GIMP_IMAGE (projectable);
 }
 
-static GimpImageType
+static const Babl *
-gimp_image_get_image_type (GimpProjectable *projectable)
+gimp_image_get_proj_format (GimpProjectable *projectable)
 {
   GimpImagePrivate *private = GIMP_IMAGE_GET_PRIVATE (projectable);
-  GimpImageType     type;
 
-  type = GIMP_IMAGE_TYPE_FROM_BASE_TYPE (private->base_type);
+  switch (private->base_type)
+    {
+    case GIMP_RGB:
+    case GIMP_INDEXED:
+      return babl_format ("R'G'B'A u8");
 
-  return GIMP_IMAGE_TYPE_WITH_ALPHA (type);
+    case GIMP_GRAY:
+      return babl_format ("Y'A u8");
+    }
+
+  g_assert_not_reached ();
+
+  return NULL;
 }
 
 static GeglNode *

app/core/gimpprojectable.c

@@ -164,17 +164,17 @@ gimp_projectable_get_image (GimpProjectable *projectable)
   return NULL;
 }
 
-GimpImageType
+const Babl *
-gimp_projectable_get_image_type (GimpProjectable *projectable)
+gimp_projectable_get_format (GimpProjectable *projectable)
 {
   GimpProjectableInterface *iface;
 
-  g_return_val_if_fail (GIMP_IS_PROJECTABLE (projectable), 0);
+  g_return_val_if_fail (GIMP_IS_PROJECTABLE (projectable), NULL);
 
   iface = GIMP_PROJECTABLE_GET_INTERFACE (projectable);
 
-  if (iface->get_image_type)
+  if (iface->get_format)
-    return iface->get_image_type (projectable);
+    return iface->get_format (projectable);
 
   return 0;
 }

app/core/gimpprojectable.h

@@ -46,7 +46,7 @@ struct _GimpProjectableInterface
 
   /*  virtual functions  */
   GimpImage     * (* get_image)          (GimpProjectable *projectable);
-  GimpImageType   (* get_image_type)     (GimpProjectable *projectable);
+  const Babl    * (* get_format)         (GimpProjectable *projectable);
   void            (* get_offset)         (GimpProjectable *projectable,
                                           gint            *x,
                                           gint            *y);
@@ -74,7 +74,7 @@ void           gimp_projectable_flush              (GimpProjectable *projectable
 void           gimp_projectable_structure_changed  (GimpProjectable *projectable);
 
 GimpImage    * gimp_projectable_get_image          (GimpProjectable *projectable);
-GimpImageType  gimp_projectable_get_image_type     (GimpProjectable *projectable);
+const Babl   * gimp_projectable_get_format         (GimpProjectable *projectable);
 void           gimp_projectable_get_offset         (GimpProjectable *projectable,
                                                     gint            *x,
                                                     gint            *y);

app/core/gimpprojection.c

@@ -295,23 +295,8 @@ static const Babl *
 gimp_projection_get_format (GimpPickable *pickable)
 {
   GimpProjection *proj = GIMP_PROJECTION (pickable);
-  GimpImageType   type;
 
-  type = gimp_projectable_get_image_type (proj->projectable);
+  return gimp_projectable_get_format (proj->projectable);
-
-  switch (GIMP_IMAGE_TYPE_BASE_TYPE (type))
-    {
-    case GIMP_RGB:
-    case GIMP_INDEXED:
-      return babl_format ("R'G'B'A u8");
-
-    case GIMP_GRAY:
-      return babl_format ("Y'A u8");
-    }
-
-  g_assert_not_reached ();
-
-  return NULL;
 }
 
 static GeglBuffer *