cullable: Factor out untransformed check into a vfunc

Some cullable implementation may have extra information about their
expected size. The main example here are surface actors which can be scaled
by geometry scale.

Add an API to overwrite the default size / untransformed check for such cases.

https://gitlab.gnome.org/GNOME/mutter/merge_requests/1036

src/compositor/clutter-utils.c

@@ -110,23 +110,6 @@ meta_actor_vertices_are_untransformed (graphene_point3d_t *verts,
   return TRUE;
 }
 
-/* Check if an actor is "untransformed" - which actually means transformed by
- * at most a integer-translation. The integer translation, if any, is returned.
- */
-gboolean
-meta_actor_is_untransformed (ClutterActor *actor,
-                             int          *x_origin,
-                             int          *y_origin)
-{
-  gfloat widthf, heightf;
-  graphene_point3d_t verts[4];
-
-  clutter_actor_get_size (actor, &widthf, &heightf);
-  clutter_actor_get_abs_allocation_vertices (actor, verts);
-
-  return meta_actor_vertices_are_untransformed (verts, widthf, heightf, x_origin, y_origin);
-}
-
 /**
  * meta_actor_painting_untransformed:
  * @paint_width: the width of the painted area

src/compositor/clutter-utils.h

@@ -28,9 +28,6 @@ gboolean meta_actor_vertices_are_untransformed (graphene_point3d_t *verts,
                                                 float               heightf,
                                                 int                *x_origin,
                                                 int                *y_origin);
-gboolean meta_actor_is_untransformed (ClutterActor *actor,
-                                      int          *x_origin,
-                                      int          *y_origin);
 
 gboolean meta_actor_painting_untransformed (CoglFramebuffer *fb,
                                             int              paint_width,

src/compositor/meta-cullable.c

@@ -100,7 +100,7 @@ meta_cullable_cull_out_children (MetaCullable   *cullable,
       if (needs_culling && clutter_actor_has_effects (child))
         needs_culling = FALSE;
 
-      if (needs_culling && !meta_actor_is_untransformed (child, NULL, NULL))
+      if (needs_culling && !meta_cullable_is_untransformed (META_CULLABLE (child)))
         needs_culling = FALSE;
 
       if (needs_culling)
@@ -149,9 +149,23 @@ meta_cullable_reset_culling_children (MetaCullable *cullable)
     }
 }
 
+static gboolean
+meta_cullable_default_is_untransformed (MetaCullable *cullable)
+{
+  float width, height;
+  graphene_point3d_t verts[4];
+
+  clutter_actor_get_size (CLUTTER_ACTOR (cullable), &width, &height);
+  clutter_actor_get_abs_allocation_vertices (CLUTTER_ACTOR (cullable), verts);
+
+  return meta_actor_vertices_are_untransformed (verts, width, height,
+                                                NULL, NULL);
+}
+
 static void
 meta_cullable_default_init (MetaCullableInterface *iface)
 {
+  iface->is_untransformed = meta_cullable_default_is_untransformed;
 }
 
 /**
@@ -186,6 +200,19 @@ meta_cullable_cull_out (MetaCullable   *cullable,
   META_CULLABLE_GET_IFACE (cullable)->cull_out (cullable, unobscured_region, clip_region);
 }
 
+/**
+ * meta_cullable_is_untransformed:
+ * @cullable: The #MetaCullable
+ *
+ * Check if a cullable is "untransformed" - which actually means transformed by
+ * at most a integer-translation.
+ */
+gboolean
+meta_cullable_is_untransformed (MetaCullable *cullable)
+{
+  return META_CULLABLE_GET_IFACE (cullable)->is_untransformed (cullable);
+}
+
 /**
  * meta_cullable_reset_culling:
  * @cullable: The #MetaCullable

src/compositor/meta-cullable.h

@@ -39,12 +39,14 @@ struct _MetaCullableInterface
   void (* cull_out)      (MetaCullable   *cullable,
                           cairo_region_t *unobscured_region,
                           cairo_region_t *clip_region);
+  gboolean (* is_untransformed) (MetaCullable *cullable);
   void (* reset_culling) (MetaCullable  *cullable);
 };
 
 void meta_cullable_cull_out (MetaCullable   *cullable,
                              cairo_region_t *unobscured_region,
                              cairo_region_t *clip_region);
+gboolean meta_cullable_is_untransformed (MetaCullable *cullable);
 void meta_cullable_reset_culling (MetaCullable *cullable);
 
 /* Utility methods for implementations */

src/compositor/meta-window-group.c

@@ -89,7 +89,7 @@ meta_window_group_paint (ClutterActor        *actor,
                                               screen_height,
                                               &paint_x_origin,
                                               &paint_y_origin) ||
-          !meta_actor_is_untransformed (actor, NULL, NULL))
+          !meta_cullable_is_untransformed (META_CULLABLE (actor)))
         {
           CLUTTER_ACTOR_CLASS (meta_window_group_parent_class)->paint (actor,
                                                                        paint_context);