[mutter] clutter/actor: Add API to pick frame clock

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit f9eb140e62a4c56f12b8d205f220719f2d0ae3b5
Author: Jonas Ådahl <jadahl gmail com>
Date:   Fri May 22 23:04:31 2020 +0200

    clutter/actor: Add API to pick frame clock
    
    The frame clock wouldn't be useable yet, but none the less, add API to
    get the frame clock best suited for driving the actor. Currently this
    translates to the fastest one, but that might change.
    
    https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1285

 clutter/clutter/clutter-actor.c | 35 +++++++++++++++++++++++++++++++++++
 clutter/clutter/clutter-actor.h |  3 +++
 2 files changed, 38 insertions(+)
---
diff --git a/clutter/clutter/clutter-actor.c b/clutter/clutter/clutter-actor.c
index 821eddf11f..095e80ed5f 100644
--- a/clutter/clutter/clutter-actor.c
+++ b/clutter/clutter/clutter-actor.c
@@ -652,6 +652,7 @@
 #include "clutter-scriptable.h"
 #include "clutter-script-private.h"
 #include "clutter-stage-private.h"
+#include "clutter-stage-view-private.h"
 #include "clutter-timeline.h"
 #include "clutter-transition.h"
 #include "clutter-units.h"
@@ -16250,6 +16251,40 @@ clutter_actor_peek_stage_views (ClutterActor *self)
   return self->priv->stage_views;
 }
 
+/**
+ * clutter_actor_pick_frame_clock:
+ * @self: a #ClutterActor
+ *
+ * Pick the most suitable frame clock for driving animations for this actor.
+ *
+ * Returns: (transfer none): a #ClutterFrameClock
+ */
+ClutterFrameClock *
+clutter_actor_pick_frame_clock (ClutterActor *self)
+{
+  float max_refresh_rate = 0.0;
+  ClutterStageView *best_view = NULL;
+  GList *l;
+
+  for (l = self->priv->stage_views; l; l = l->next)
+    {
+      ClutterStageView *view = l->data;
+      float refresh_rate;
+
+      refresh_rate = clutter_stage_view_get_refresh_rate (view);
+      if (refresh_rate > max_refresh_rate)
+        {
+          best_view = view;
+          max_refresh_rate = refresh_rate;
+        }
+    }
+
+  if (best_view)
+    return clutter_stage_view_get_frame_clock (best_view);
+  else
+    return NULL;
+}
+
 /**
  * clutter_actor_has_overlaps:
  * @self: A #ClutterActor
diff --git a/clutter/clutter/clutter-actor.h b/clutter/clutter/clutter-actor.h
index 128acac1a3..e5fa72baed 100644
--- a/clutter/clutter/clutter-actor.h
+++ b/clutter/clutter/clutter-actor.h
@@ -924,6 +924,9 @@ GList * clutter_actor_peek_stage_views (ClutterActor *self);
 CLUTTER_EXPORT
 void clutter_actor_invalidate_transform (ClutterActor *self);
 
+CLUTTER_EXPORT
+ClutterFrameClock * clutter_actor_pick_frame_clock (ClutterActor *self);
+
 G_END_DECLS
 
 #endif /* __CLUTTER_ACTOR_H__ */