clutter/frame: Allow setting a backend release function

The one set by the native backend is empty, but it will be used later.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2855>

clutter/clutter/clutter-frame-clock.c

@@ -735,7 +735,7 @@ clutter_frame_clock_dispatch (ClutterFrameClock *frame_clock,
   if (iface->new_frame)
     frame = iface->new_frame (frame_clock, frame_clock->listener.user_data);
   if (!frame)
-    frame = clutter_frame_new (ClutterFrame);
+    frame = clutter_frame_new (ClutterFrame, NULL);
 
   frame->frame_count = frame_count;
   frame->has_target_presentation_time = frame_clock->is_next_presentation_time_valid;

clutter/clutter/clutter-frame-private.h

@@ -20,9 +20,12 @@
 
 #include "clutter/clutter-frame.h"
 
+typedef void (* ClutterFrameRelease) (ClutterFrame *frame);
+
 struct _ClutterFrame
 {
   grefcount ref_count;
+  ClutterFrameRelease release;
 
   int64_t frame_count;
 
@@ -34,10 +37,11 @@ struct _ClutterFrame
 };
 
 CLUTTER_EXPORT
-gpointer clutter_frame_new (size_t size);
+gpointer clutter_frame_new (size_t              size,
+                            ClutterFrameRelease release);
 
-#define clutter_frame_new(FrameType) \
-  ((FrameType *) (clutter_frame_new (sizeof (FrameType))))
+#define clutter_frame_new(FrameType, release) \
+  ((FrameType *) (clutter_frame_new (sizeof (FrameType), release)))
 
 ClutterFrameResult clutter_frame_get_result (ClutterFrame *frame);
 

clutter/clutter/clutter-frame.c

@@ -32,11 +32,16 @@ void
 clutter_frame_unref (ClutterFrame *frame)
 {
   if (g_ref_count_dec (&frame->ref_count))
-    g_free (frame);
+    {
+      if (frame->release)
+        frame->release (frame);
+      g_free (frame);
+    }
 }
 
 gpointer
-(clutter_frame_new) (size_t size)
+(clutter_frame_new) (size_t              size,
+                     ClutterFrameRelease release)
 {
   ClutterFrame *frame;
 
@@ -44,6 +49,7 @@ gpointer
 
   frame = g_malloc0 (size);
   g_ref_count_init (&frame->ref_count);
+  frame->release = release;
 
   return frame;
 }

src/backends/native/meta-frame-native.c

@@ -28,8 +28,13 @@ struct _MetaFrameNative
   ClutterFrame base;
 };
 
+static void
+meta_frame_native_release (ClutterFrame *frame)
+{
+}
+
 MetaFrameNative *
 meta_frame_native_new (void)
 {
-  return clutter_frame_new (MetaFrameNative);
+  return clutter_frame_new (MetaFrameNative, meta_frame_native_release);
 }