cursor-renderer: Add a cursor painted signal

This signal allows interested parties to be notified of a new cursor
frame being painted regardless of whether it's being painted by the
backend directly or if it's a software rendered cursor frame handled
by clutter.

https://bugzilla.gnome.org/show_bug.cgi?id=749913

src/backends/meta-cursor-renderer.c

@@ -42,11 +42,25 @@ struct _MetaCursorRendererPrivate
   MetaCursorSprite *displayed_cursor;
   MetaOverlay *stage_overlay;
   gboolean handled_by_backend;
+  guint post_paint_func_id;
 };
 typedef struct _MetaCursorRendererPrivate MetaCursorRendererPrivate;
 
+enum {
+  CURSOR_PAINTED,
+  LAST_SIGNAL
+};
+static guint signals[LAST_SIGNAL];
+
 G_DEFINE_TYPE_WITH_PRIVATE (MetaCursorRenderer, meta_cursor_renderer, G_TYPE_OBJECT);
 
+void
+meta_cursor_renderer_emit_painted (MetaCursorRenderer *renderer,
+                                   MetaCursorSprite   *cursor_sprite)
+{
+  g_signal_emit (renderer, signals[CURSOR_PAINTED], 0, cursor_sprite);
+}
+
 static void
 queue_redraw (MetaCursorRenderer *renderer,
               MetaCursorSprite   *cursor_sprite)
@@ -76,6 +90,19 @@ queue_redraw (MetaCursorRenderer *renderer,
                                     texture, &rect);
 }
 
+static gboolean
+meta_cursor_renderer_post_paint (gpointer data)
+{
+  MetaCursorRenderer *renderer = META_CURSOR_RENDERER (data);
+  MetaCursorRendererPrivate *priv =
+    meta_cursor_renderer_get_instance_private (renderer);
+
+  if (priv->displayed_cursor && !priv->handled_by_backend)
+    meta_cursor_renderer_emit_painted (renderer, priv->displayed_cursor);
+
+  return TRUE;
+}
+
 static gboolean
 meta_cursor_renderer_real_update_cursor (MetaCursorRenderer *renderer,
                                          MetaCursorSprite   *cursor_sprite)
@@ -97,6 +124,8 @@ meta_cursor_renderer_finalize (GObject *object)
   if (priv->stage_overlay)
     meta_stage_remove_cursor_overlay (META_STAGE (stage), priv->stage_overlay);
 
+  clutter_threads_remove_repaint_func (priv->post_paint_func_id);
+
   G_OBJECT_CLASS (meta_cursor_renderer_parent_class)->finalize (object);
 }
 
@@ -107,11 +136,27 @@ meta_cursor_renderer_class_init (MetaCursorRendererClass *klass)
 
   object_class->finalize = meta_cursor_renderer_finalize;
   klass->update_cursor = meta_cursor_renderer_real_update_cursor;
+
+  signals[CURSOR_PAINTED] = g_signal_new ("cursor-painted",
+                                          G_TYPE_FROM_CLASS (klass),
+                                          G_SIGNAL_RUN_LAST,
+                                          0,
+                                          NULL, NULL, NULL,
+                                          G_TYPE_NONE, 1,
+                                          G_TYPE_POINTER);
 }
 
 static void
 meta_cursor_renderer_init (MetaCursorRenderer *renderer)
 {
+  MetaCursorRendererPrivate *priv =
+    meta_cursor_renderer_get_instance_private (renderer);
+
+  priv->post_paint_func_id =
+    clutter_threads_add_repaint_func_full (CLUTTER_REPAINT_FLAGS_POST_PAINT,
+                                           meta_cursor_renderer_post_paint,
+                                           renderer,
+                                           NULL);
 }
 
 MetaRectangle

src/backends/meta-cursor-renderer.h

@@ -78,4 +78,7 @@ void meta_cursor_renderer_realize_cursor_from_xcursor (MetaCursorRenderer *rende
                                                        MetaCursorSprite   *cursor_sprite,
                                                        XcursorImage       *xc_image);
 
+void meta_cursor_renderer_emit_painted (MetaCursorRenderer *renderer,
+                                        MetaCursorSprite   *cursor_sprite);
+
 #endif /* META_CURSOR_RENDERER_H */

src/backends/native/meta-cursor-renderer-native.c

@@ -216,6 +216,7 @@ update_hw_cursor (MetaCursorRendererNative *native,
   MetaCRTC *crtcs;
   unsigned int i, n_crtcs;
   MetaRectangle rect;
+  gboolean painted = FALSE;
 
   monitors = meta_monitor_manager_get ();
   meta_monitor_manager_get_resources (monitors, NULL, NULL, &crtcs, &n_crtcs, NULL, NULL);
@@ -247,8 +248,12 @@ update_hw_cursor (MetaCursorRendererNative *native,
           drmModeMoveCursor (priv->drm_fd, crtcs[i].crtc_id,
                              rect.x - crtc_rect->x,
                              rect.y - crtc_rect->y);
+          painted = TRUE;
         }
     }
+
+  if (painted)
+    meta_cursor_renderer_emit_painted (renderer, cursor_sprite);
 }
 
 static gboolean