clutter/actor: Add semi-private API to check for transitions

Transitions are used for animating actors when e.g. going from/to
fullscreen, and the like. We need to know such things when deciding
whether to avoid compositing a window actor, so make add API visible to
mutter that checks whether there are any transitions active.

Original Mutter commit: https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/798/diffs?commit_id=bc178b711ffbd8db0b7cfecefb6f67edf4e0254f

Author: Sunderland93

clutter/clutter/clutter-actor.c

@@ -20020,6 +20020,23 @@ clutter_actor_get_transition (ClutterActor *self,
   return clos->transition;
 }
 
+/**
+ * clutter_actor_has_transitions: (skip)
+ */
+gboolean
+clutter_actor_has_transitions (ClutterActor *self)
+{
+  const ClutterAnimationInfo *info;
+
+  g_return_val_if_fail (CLUTTER_IS_ACTOR (self), FALSE);
+
+  info = _clutter_actor_get_animation_info_or_defaults (self);
+  if (info->transitions == NULL)
+    return FALSE;
+
+  return g_hash_table_size (info->transitions) > 0;
+}
+
 /**
  * clutter_actor_save_easing_state:
  * @self: a #ClutterActor

clutter/clutter/clutter-muffin.h

@@ -83,6 +83,10 @@ void clutter_stage_get_device_coords (ClutterStage         *stage,
                                       ClutterInputDevice   *device,
                                       ClutterEventSequence *sequence,
                                       graphene_point_t     *coords);
+
+CLUTTER_EXPORT
+gboolean clutter_actor_has_transitions (ClutterActor *actor);
+
 #undef __CLUTTER_H_INSIDE__
 
 #endif /* __CLUTTER_MUFFIN_H__ */