[mutter] window-actor: Make freezing and thawing of actor updates public API

[Robert Mader <rmader src gnome org>]

commit fb474fb612134eb611afe151620bc798434ef1b0
Author: Jonas Dreßler <verdre v0yd nl>
Date:   Tue May 12 12:04:28 2020 +0200

    window-actor: Make freezing and thawing of actor updates public API
    
    As explained in the last commit, gnome-shell needs to be able to thaw
    window actor updates during its size-change effect is active.
    
    So make meta_window_actor_freeze() and meta_window_actor_thaw() public
    API, which will allow the shell to freeze and thaw actor updates itself.
    
    https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1250

 src/compositor/meta-window-actor.c | 34 ++++++++++++++++++++++++++++------
 src/meta/meta-window-actor.h       |  6 ++++++
 2 files changed, 34 insertions(+), 6 deletions(-)
---
diff --git a/src/compositor/meta-window-actor.c b/src/compositor/meta-window-actor.c
index 1207f1fb7c..fc8ac2c2ef 100644
--- a/src/compositor/meta-window-actor.c
+++ b/src/compositor/meta-window-actor.c
@@ -272,11 +272,23 @@ meta_window_actor_set_frozen (MetaWindowActor *self,
   META_WINDOW_ACTOR_GET_CLASS (self)->set_frozen (self, frozen);
 }
 
-static void
+/**
+ * meta_window_actor_freeze:
+ * @self: The #MetaWindowActor
+ *
+ * Freezes the #MetaWindowActor, which inhibits updates and geometry
+ * changes of the window. This property is refcounted, so make sure
+ * to call meta_window_actor_thaw() the exact same amount of times
+ * as this function to allow updates again.
+ */
+void
 meta_window_actor_freeze (MetaWindowActor *self)
 {
-  MetaWindowActorPrivate *priv =
-    meta_window_actor_get_instance_private (self);
+  MetaWindowActorPrivate *priv;
+
+  g_return_if_fail (META_IS_WINDOW_ACTOR (self));
+
+  priv = meta_window_actor_get_instance_private (self);
 
   if (priv->freeze_count == 0 && priv->surface)
     meta_window_actor_set_frozen (self, TRUE);
@@ -300,11 +312,21 @@ meta_window_actor_sync_thawed_state (MetaWindowActor *self)
   meta_window_actor_sync_actor_geometry (self, FALSE);
 }
 
-static void
+/**
+ * meta_window_actor_thaw:
+ * @self: The #MetaWindowActor
+ *
+ * Thaws/unfreezes the #MetaWindowActor to allow updates and geometry
+ * changes after a window was frozen using meta_window_actor_freeze().
+ */
+void
 meta_window_actor_thaw (MetaWindowActor *self)
 {
-  MetaWindowActorPrivate *priv =
-    meta_window_actor_get_instance_private (self);
+  MetaWindowActorPrivate *priv;
+
+  g_return_if_fail (META_IS_WINDOW_ACTOR (self));
+
+  priv = meta_window_actor_get_instance_private (self);
 
   if (priv->freeze_count <= 0)
     g_error ("Error in freeze/thaw accounting");
diff --git a/src/meta/meta-window-actor.h b/src/meta/meta-window-actor.h
index 7d3b96e593..6e18683a27 100644
--- a/src/meta/meta-window-actor.h
+++ b/src/meta/meta-window-actor.h
@@ -51,6 +51,12 @@ META_EXPORT
 cairo_surface_t * meta_window_actor_get_image (MetaWindowActor       *self,
                                                cairo_rectangle_int_t *clip);
 
+META_EXPORT
+void meta_window_actor_freeze (MetaWindowActor *self);
+
+META_EXPORT
+void meta_window_actor_thaw (MetaWindowActor *self);
+
 typedef enum
 {
   META_SHADOW_MODE_AUTO,