[mutter] clutter/master-clock: Destroy source when paused

[Jonas Ådahl <jadahl src gnome org>]

commit 626c3745e2678eaa825b188bfe1f88404534b455
Author: Jonas Ådahl <jadahl gmail com>
Date:   Wed Nov 14 13:22:05 2018 +0100

    clutter/master-clock: Destroy source when paused
    
    Pausing the master clock didn't actually pause it if there was already a
    scheduled frame in progress. This is problematic if one actually expects
    to see no new frame scheduling to happen after pausing, for example it
    caused actor 'pre-paint' to be signalled on actors, but nothing was ever
    painted.
    
    Avoid this by destroying the master clock source when pausing, and then
    recreating it when resuming.
    
    https://gitlab.gnome.org/GNOME/mutter/merge_requests/309

 clutter/clutter/clutter-master-clock-default.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)
---
diff --git a/clutter/clutter/clutter-master-clock-default.c b/clutter/clutter/clutter-master-clock-default.c
index 440382e76..d28dd474f 100644
--- a/clutter/clutter/clutter-master-clock-default.c
+++ b/clutter/clutter/clutter-master-clock-default.c
@@ -470,6 +470,8 @@ clutter_clock_source_new (ClutterMasterClockDefault *master_clock)
   ClutterClockSource *clock_source = (ClutterClockSource *) source;
 
   g_source_set_name (source, "Clutter master clock");
+  g_source_set_priority (source, CLUTTER_PRIORITY_REDRAW);
+  g_source_set_can_recurse (source, FALSE);
   clock_source->master_clock = master_clock;
 
   return source;
@@ -615,8 +617,6 @@ clutter_master_clock_default_init (ClutterMasterClockDefault *self)
   self->frame_budget = G_USEC_PER_SEC / 60;
 #endif
 
-  g_source_set_priority (source, CLUTTER_PRIORITY_REDRAW);
-  g_source_set_can_recurse (source, FALSE);
   g_source_attach (source, NULL);
 }
 
@@ -675,6 +675,16 @@ clutter_master_clock_default_set_paused (ClutterMasterClock *clock,
 {
   ClutterMasterClockDefault *master_clock = (ClutterMasterClockDefault *) clock;
 
+  if (paused && !master_clock->paused)
+    {
+      g_clear_pointer (&master_clock->source, g_source_destroy);
+    }
+  else if (!paused && master_clock->paused)
+    {
+      master_clock->source = clutter_clock_source_new (master_clock);
+      g_source_attach (master_clock->source, NULL);
+    }
+
   master_clock->paused = !!paused;
 }