clutter/actor: Add private API to get whether we're painting unmapped

Add new private API to ClutterActor, returning TRUE in case the actor is
being painted while unmapped. This is useful for implementations of the
paint() vfunc or for signal handlers of the "notify::mapped" signal.

Use this API in CallyActor to properly detect "notify::mapped" emissions
while painting unmapped, this fixes detecting the case where
painting-unmapped is used for screencasting.

https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1366

clutter/clutter/cally/cally-actor.c

@@ -72,6 +72,8 @@
 #include <glib.h>
 #include <clutter/clutter.h>
 
+#include "clutter/clutter-actor-private.h"
+
 #ifdef CLUTTER_WINDOWING_X11
 #include <clutter/x11/clutter-x11.h>
 #endif
@@ -972,7 +974,7 @@ cally_actor_real_notify_clutter (GObject    *obj,
        * paint it; we don't want this to generate an ATK
        * state change
        */
-      if (clutter_actor_is_in_clone_paint (actor))
+      if (clutter_actor_is_painting_unmapped (actor))
         return;
 
       state = ATK_STATE_SHOWING;

clutter/clutter/clutter-actor-private.h

@@ -293,6 +293,8 @@ void clutter_actor_update_stage_views (ClutterActor *self,
 
 void clutter_actor_queue_immediate_relayout (ClutterActor *self);
 
+gboolean clutter_actor_is_painting_unmapped (ClutterActor *self);
+
 G_END_DECLS
 
 #endif /* __CLUTTER_ACTOR_PRIVATE_H__ */

clutter/clutter/clutter-actor.c

@@ -14921,6 +14921,14 @@ clutter_actor_is_in_clone_paint (ClutterActor *self)
   return FALSE;
 }
 
+gboolean
+clutter_actor_is_painting_unmapped (ClutterActor *self)
+{
+  g_return_val_if_fail (CLUTTER_IS_ACTOR (self), FALSE);
+
+  return self->priv->unmapped_paint_branch_counter > 0;
+}
+
 gboolean
 clutter_actor_has_damage (ClutterActor *actor)
 {