[mutter] clutter/stage-view: Have each stage view create its own frame clock

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

commit 2e358f3c43d2d73e2f849b50c9c18edc0e279097
Author: Jonas Ådahl <jadahl gmail com>
Date:   Fri May 22 22:57:39 2020 +0200

    clutter/stage-view: Have each stage view create its own frame clock
    
    The frame clock is meant to eventually drive the painting of the view,
    in contrast to the master frame clock painting every view on the stage.
    Right now it's a useless place holder.
    
    https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1285

 clutter/clutter/clutter-stage-view-private.h |  3 ++
 clutter/clutter/clutter-stage-view.c         | 42 ++++++++++++++++++++++++++++
 2 files changed, 45 insertions(+)
---
diff --git a/clutter/clutter/clutter-stage-view-private.h b/clutter/clutter/clutter-stage-view-private.h
index 36c52e8ad6..85d02e9de5 100644
--- a/clutter/clutter/clutter-stage-view-private.h
+++ b/clutter/clutter/clutter-stage-view-private.h
@@ -19,6 +19,7 @@
 #define __CLUTTER_STAGE_VIEW_PRIVATE_H__
 
 #include "clutter/clutter-stage-view.h"
+#include "clutter/clutter-types.h"
 
 void clutter_stage_view_after_paint (ClutterStageView *view,
                                      cairo_region_t   *redraw_clip);
@@ -62,4 +63,6 @@ void clutter_stage_view_transform_rect_to_onscreen (ClutterStageView
                                                     int                          dst_height,
                                                     cairo_rectangle_int_t       *dst_rect);
 
+ClutterFrameClock * clutter_stage_view_get_frame_clock (ClutterStageView *view);
+
 #endif /* __CLUTTER_STAGE_VIEW_PRIVATE_H__ */
diff --git a/clutter/clutter/clutter-stage-view.c b/clutter/clutter/clutter-stage-view.c
index ebe3fe92bf..83ffe4e837 100644
--- a/clutter/clutter/clutter-stage-view.c
+++ b/clutter/clutter/clutter-stage-view.c
@@ -24,6 +24,7 @@
 #include <math.h>
 
 #include "clutter/clutter-damage-history.h"
+#include "clutter/clutter-frame-clock.h"
 #include "clutter/clutter-private.h"
 #include "clutter/clutter-mutter.h"
 #include "cogl/cogl.h"
@@ -76,6 +77,7 @@ typedef struct _ClutterStageViewPrivate
   cairo_region_t *redraw_clip;
 
   float refresh_rate;
+  ClutterFrameClock *frame_clock;
 
   guint dirty_viewport   : 1;
   guint dirty_projection : 1;
@@ -999,6 +1001,41 @@ clutter_stage_view_take_scanout (ClutterStageView *view)
   return g_steal_pointer (&priv->next_scanout);
 }
 
+ClutterFrameClock *
+clutter_stage_view_get_frame_clock (ClutterStageView *view)
+{
+  ClutterStageViewPrivate *priv =
+    clutter_stage_view_get_instance_private (view);
+
+  return priv->frame_clock;
+}
+
+static void
+handle_frame_clock_before_frame (ClutterFrameClock *frame_clock,
+                                 int64_t            frame_count,
+                                 gpointer           user_data)
+{
+  ClutterStageView *view = user_data;
+  ClutterStageViewPrivate *priv =
+    clutter_stage_view_get_instance_private (view);
+
+  _clutter_stage_process_queued_events (priv->stage);
+}
+
+static ClutterFrameResult
+handle_frame_clock_frame (ClutterFrameClock *frame_clock,
+                          int64_t            frame_count,
+                          int64_t            time_us,
+                          gpointer           user_data)
+{
+  return CLUTTER_FRAME_RESULT_IDLE;
+}
+
+static const ClutterFrameListenerIface frame_clock_listener_iface = {
+  .before_frame = handle_frame_clock_before_frame,
+  .frame = handle_frame_clock_frame,
+};
+
 static void
 sanity_check_framebuffer (ClutterStageView *view)
 {
@@ -1122,6 +1159,10 @@ clutter_stage_view_constructed (GObject *object)
   if (priv->use_shadowfb)
     init_shadowfb (view);
 
+  priv->frame_clock = clutter_frame_clock_new (priv->refresh_rate,
+                                               &frame_clock_listener_iface,
+                                               view);
+
   G_OBJECT_CLASS (clutter_stage_view_parent_class)->constructed (object);
 }
 
@@ -1148,6 +1189,7 @@ clutter_stage_view_dispose (GObject *object)
   g_clear_pointer (&priv->offscreen, cogl_object_unref);
   g_clear_pointer (&priv->offscreen_pipeline, cogl_object_unref);
   g_clear_pointer (&priv->redraw_clip, cairo_region_destroy);
+  g_clear_object (&priv->frame_clock);
 
   G_OBJECT_CLASS (clutter_stage_view_parent_class)->dispose (object);
 }