[clutter] gdk: Enable clock updates when timelines are added to the clock

[Lionel Landwerlin <llandwerlin src gnome org>]

commit b9df8524f0c0835ef82737bb65282bc1214a1d94
Author: Lionel Landwerlin <llandwerlin gmail com>
Date:   Tue Sep 22 17:27:42 2015 +0100

    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

 clutter/gdk/clutter-master-clock-gdk.c |   53 ++++++++++++++++++++++++++++++-
 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 ff102a7..90c4cce 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