gdk: Enable clock updates when timelines are added to the clock

Enable animation updates from the GdkFrameClock whenever any timeline is
added to the ClutterMasterClockGdk. This may improve animation
smoothness (depending on the GDK backend in use) because it allows GDK
to tweak its frame timing for animation purposes.

https://bugzilla.gnome.org/show_bug.cgi?id=755357

1 files changed, 51 insertions, 2 deletions

diff --git a/clutter/gdk/clutter-master-clock-gdk.c b/clutter/gdk/clutter-master-clock-gdk.c
index ff102a754..90c4cce79 100644
--- a/clutter/gdk/clutter-master-clock-gdk.c
+++ b/clutter/gdk/clutter-master-clock-gdk.c
@@ -114,6 +114,32 @@ master_clock_schedule_forced_stages_updates (ClutterMasterClockGdk *master_clock
 }
 
 static void
+master_clock_sync_frame_clock_update (ClutterMasterClockGdk *master_clock)
+{
+  gboolean updating = master_clock->timelines != NULL;
+  gpointer frame_clock, stage_list;
+  GHashTableIter iter;
+
+  g_hash_table_iter_init (&iter, master_clock->clock_to_stage);
+  while (g_hash_table_iter_next (&iter, &frame_clock, &stage_list))
+    {
+      gboolean clock_updating =
+        GPOINTER_TO_UINT (g_object_get_data (frame_clock,
+                                             "clutter-master-clock-updating"));
+      if (clock_updating != updating)
+        {
+          if (updating)
+            gdk_frame_clock_begin_updating (GDK_FRAME_CLOCK (frame_clock));
+          else
+            gdk_frame_clock_end_updating (GDK_FRAME_CLOCK (frame_clock));
+          g_object_set_data (frame_clock,
+                             "clutter-master-clock-updating",
+                             GUINT_TO_POINTER (updating));
+        }
+    }
+}
+
+static void
 master_clock_schedule_stage_update (ClutterMasterClockGdk *master_clock,
                                     ClutterStage          *stage,
                                     GdkFrameClock         *frame_clock)
@@ -306,9 +332,19 @@ clutter_master_clock_gdk_remove_stage_clock (ClutterMasterClockGdk *master_clock
     {
       if (stages->next == NULL)
         {
+          /* Deleting the last stage linked to a given clock. We can stop
+             listening to that clock and also tell the clock we're finish
+             updating it. */
+          if (GPOINTER_TO_UINT (g_object_get_data (frame_clock,
+                                                   "clutter-master-clock-updating")))
+            {
+              gdk_frame_clock_end_updating (GDK_FRAME_CLOCK (frame_clock));
+              g_object_set_data (frame_clock, "clutter-master-clock-updating", NULL);
+            }
           g_signal_handlers_disconnect_by_func (frame_clock,
                                                 clutter_master_clock_gdk_update,
                                                 master_clock);
+
           g_hash_table_remove (master_clock->clock_to_stage, frame_clock);
           g_list_free (stages);
         }
@@ -349,7 +385,12 @@ clutter_master_clock_gdk_add_stage_clock (ClutterMasterClockGdk *master_clock,
     stages = g_list_append (stages, stage);
 
   if (master_clock->timelines != NULL)
-    _clutter_master_clock_start_running ((ClutterMasterClock *) master_clock);
+    {
+      _clutter_master_clock_start_running ((ClutterMasterClock *) master_clock);
+      /* We only need to synchronize the frame clock state if we have
+         timelines running. */
+      master_clock_sync_frame_clock_update (master_clock);
+    }
 }
 
 static void
@@ -501,7 +542,11 @@ clutter_master_clock_gdk_add_timeline (ClutterMasterClock *clock,
                                              timeline);
 
   if (is_first)
-    _clutter_master_clock_start_running (clock);
+    {
+      _clutter_master_clock_start_running (clock);
+      /* Sync frame clock update state if needed. */
+      master_clock_sync_frame_clock_update (master_clock);
+    }
 }
 
 static void
@@ -512,6 +557,10 @@ clutter_master_clock_gdk_remove_timeline (ClutterMasterClock *clock,
 
   master_clock->timelines = g_slist_remove (master_clock->timelines,
                                             timeline);
+
+  /* Sync frame clock update state if we have no more timelines running. */
+  if (master_clock->timelines == NULL)
+    master_clock_sync_frame_clock_update (master_clock);
 }
 
 static void