ClutterStage: Replace clutter_stage_set_paint_callback() with ::after-paint signal

clutter_stage_set_paint_callback() has the disadvantage that it only
works for a single caller, and subsequent callers will overwrite and
break previous callers. Replace it with an ::after-paint signal that is
emitted at the same point - after all painting for the stage is
completed but before the drawing is presented to the screen.

https://bugzilla.gnome.org/show_bug.cgi?id=732342

clutter/clutter-stage.c

@@ -146,7 +146,6 @@ struct _ClutterStagePrivate
 
   ClutterStageState current_state;
 
-  ClutterStagePaintFunc paint_callback;
   gpointer paint_data;
   GDestroyNotify paint_notify;
 
@@ -192,6 +191,7 @@ enum
   ACTIVATE,
   DEACTIVATE,
   DELETE_EVENT,
+  AFTER_PAINT,
 
   LAST_SIGNAL
 };
@@ -202,7 +202,6 @@ static const ClutterColor default_stage_color = { 255, 255, 255, 255 };
 
 static void clutter_stage_maybe_finish_queue_redraws (ClutterStage *stage);
 static void free_queue_redraw_entry (ClutterStageQueueRedrawEntry *entry);
-static void clutter_stage_invoke_paint_callback (ClutterStage *stage);
 
 static void clutter_container_iface_init (ClutterContainerIface *iface);
 
@@ -688,7 +687,7 @@ _clutter_stage_do_paint (ClutterStage                *stage,
   _clutter_stage_update_active_framebuffer (stage);
   clutter_actor_paint (CLUTTER_ACTOR (stage));
 
-  clutter_stage_invoke_paint_callback (stage);
+  g_signal_emit (stage, stage_signals[AFTER_PAINT], 0);
 }
 
 /* If we don't implement this here, we get the paint function
@@ -2211,6 +2210,23 @@ clutter_stage_class_init (ClutterStageClass *klass)
                   G_TYPE_BOOLEAN, 1,
                   CLUTTER_TYPE_EVENT | G_SIGNAL_TYPE_STATIC_SCOPE);
 
+  /**
+   * ClutterStage::after-paint:
+   * @stage: the stage that received the event
+   *
+   * The ::after-paint signal is emitted after the stage is painted,
+   * but before the results are displayed on the screen.
+   *
+   * Since: 1.20
+   */
+  stage_signals[AFTER_PAINT] =
+    g_signal_new (I_("after-paint"),
+                  G_TYPE_FROM_CLASS (gobject_class),
+                  G_SIGNAL_RUN_LAST,
+                  0, /* no corresponding vfunc */
+                  NULL, NULL, NULL,
+                  G_TYPE_NONE, 0);
+
   klass->fullscreen = clutter_stage_real_fullscreen;
   klass->activate = clutter_stage_real_activate;
   klass->deactivate = clutter_stage_real_deactivate;
@@ -4593,45 +4609,6 @@ clutter_stage_skip_sync_delay (ClutterStage *stage)
     _clutter_stage_window_schedule_update (stage_window, -1);
 }
 
-/**
- * clutter_stage_set_paint_callback:
- * @stage: a #ClutterStage
- * @callback: (allow-none): a callback
- * @data: (allow-none): data to be passed to @callback
- * @notify: (allow-none): function to be called when the callback is removed
- *
- * Sets a callback function to be invoked after the @stage has been
- * painted.
- *
- * Since: 1.14
- */
-void
-clutter_stage_set_paint_callback (ClutterStage          *stage,
-                                  ClutterStagePaintFunc  callback,
-                                  gpointer               data,
-                                  GDestroyNotify         notify)
-{
-  ClutterStagePrivate *priv;
-
-  g_return_if_fail (CLUTTER_IS_STAGE (stage));
-
-  priv = stage->priv;
-
-  if (priv->paint_notify != NULL)
-    priv->paint_notify (priv->paint_data);
-
-  priv->paint_callback = callback;
-  priv->paint_data = data;
-  priv->paint_notify = notify;
-}
-
-static void
-clutter_stage_invoke_paint_callback (ClutterStage *stage)
-{
-  if (stage->priv->paint_callback != NULL)
-    stage->priv->paint_callback (stage, stage->priv->paint_data);
-}
-
 void
 _clutter_stage_set_scale_factor (ClutterStage *stage,
                                  int           factor)

clutter/clutter-stage.h

@@ -243,15 +243,6 @@ void            clutter_stage_set_sync_delay                    (ClutterStage
                                                                  gint                   sync_delay);
 CLUTTER_AVAILABLE_IN_1_14
 void            clutter_stage_skip_sync_delay                   (ClutterStage          *stage);
-
-typedef void (* ClutterStagePaintFunc) (ClutterStage *stage,
-                                        gpointer      data);
-
-CLUTTER_AVAILABLE_IN_1_14
-void            clutter_stage_set_paint_callback                (ClutterStage          *stage,
-                                                                 ClutterStagePaintFunc  callback,
-                                                                 gpointer               data,
-                                                                 GDestroyNotify         notify);
 #endif
 
 G_END_DECLS

doc/reference/clutter/clutter-sections.txt

@@ -669,7 +669,6 @@ clutter_stage_get_accept_focus
 
 <SUBSECTION>
 ClutterStagePaintFunc
-clutter_stage_set_paint_callback
 clutter_stage_set_sync_delay
 clutter_stage_skip_sync_delay
 

tests/conform/actor-offscreen-limit-max-size.c

@@ -75,10 +75,8 @@ actor_offscreen_limit_max_size (void)
     return;
 
   data.stage = clutter_test_get_stage ();
-  clutter_stage_set_paint_callback (CLUTTER_STAGE (data.stage),
+  g_signal_connect (data.stage, "after-paint",
-                                    check_results,
+                    G_CALLBACK (check_results), &data);
-                                    &data,
-                                    NULL);
   clutter_actor_set_size (data.stage, STAGE_WIDTH, STAGE_HEIGHT);
 
   data.actor_group1 = clutter_actor_new ();

tests/conform/actor-shader-effect.c

@@ -271,10 +271,8 @@ actor_shader_effect (void)
   clutter_actor_show (stage);
 
   was_painted = FALSE;
-  clutter_stage_set_paint_callback (CLUTTER_STAGE (stage),
+  g_signal_connect (stage, "after-paint",
-                                    paint_cb,
+                    G_CALLBACK (paint_cb), NULL);
-                                    &was_painted,
-                                    NULL);
 
   while (!was_painted)
     g_main_context_iteration (NULL, FALSE);