window-actor: Add 'damaged' signal

Make it possible to listen for damage on a window actor. For X11, the
signal is emitted when damage is reported; for Wayland, it is emitted
when any of the surfaces associated with the window is damaged.

https://gitlab.gnome.org/GNOME/mutter/merge_requests/752

3 files changed, 49 insertions, 3 deletions

diff --git a/src/compositor/meta-window-actor-private.h b/src/compositor/meta-window-actor-private.h
index 354edd314..a36217f98 100644
--- a/src/compositor/meta-window-actor-private.h
+++ b/src/compositor/meta-window-actor-private.h
@@ -93,4 +93,6 @@ void meta_window_actor_set_geometry_scale (MetaWindowActor *window_actor,
 
 int meta_window_actor_get_geometry_scale (MetaWindowActor *window_actor);
 
+void meta_window_actor_notify_damaged (MetaWindowActor *window_actor);
+
 #endif /* META_WINDOW_ACTOR_PRIVATE_H */
diff --git a/src/compositor/meta-window-actor.c b/src/compositor/meta-window-actor.c
index d2d46e6b0..f0df27666 100644
--- a/src/compositor/meta-window-actor.c
+++ b/src/compositor/meta-window-actor.c
@@ -115,6 +115,7 @@ enum
 {
   FIRST_FRAME,
   EFFECTS_COMPLETED,
+  DAMAGED,
 
   LAST_SIGNAL
 };
@@ -219,6 +220,20 @@ meta_window_actor_class_init (MetaWindowActorClass *klass)
                   NULL, NULL, NULL,
                   G_TYPE_NONE, 0);
 
+  /**
+   * MetaWindowActor::damaged:
+   * @actor: the #MetaWindowActor instance
+   *
+   * Notify that one or more of the surfaces of the window have been damaged.
+   */
+  signals[DAMAGED] =
+    g_signal_new ("damaged",
+                  G_TYPE_FROM_CLASS (object_class),
+                  G_SIGNAL_RUN_LAST,
+                  0,
+                  NULL, NULL, NULL,
+                  G_TYPE_NONE, 0);
+
   pspec = g_param_spec_object ("meta-window",
                                "MetaWindow",
                                "The displayed MetaWindow",
@@ -1498,6 +1513,8 @@ meta_window_actor_process_x11_damage (MetaWindowActor    *self,
                                        event->area.y,
                                        event->area.width,
                                        event->area.height);
+
+  meta_window_actor_notify_damaged (self);
 }
 
 void
@@ -2111,3 +2128,9 @@ meta_window_actor_from_actor (ClutterActor *actor)
 
   return NULL;
 }
+
+void
+meta_window_actor_notify_damaged (MetaWindowActor *window_actor)
+{
+  g_signal_emit (window_actor, signals[DAMAGED], 0);
+}
diff --git a/src/wayland/meta-wayland-surface.c b/src/wayland/meta-wayland-surface.c
index 9a1b45ece..12a607b47 100644
--- a/src/wayland/meta-wayland-surface.c
+++ b/src/wayland/meta-wayland-surface.c
@@ -672,6 +672,8 @@ void
 meta_wayland_surface_apply_pending_state (MetaWaylandSurface      *surface,
                                           MetaWaylandPendingState *pending)
 {
+  gboolean had_damage = FALSE;
+
   if (surface->role)
     {
       meta_wayland_surface_role_pre_commit (surface->role, pending);
@@ -778,9 +780,12 @@ meta_wayland_surface_apply_pending_state (MetaWaylandSurface      *surface,
 
   if (!cairo_region_is_empty (pending->surface_damage) ||
       !cairo_region_is_empty (pending->buffer_damage))
-    surface_process_damage (surface,
-                            pending->surface_damage,
-                            pending->buffer_damage);
+    {
+      surface_process_damage (surface,
+                              pending->surface_damage,
+                              pending->buffer_damage);
+      had_damage = TRUE;
+    }
 
   surface->offset_x += pending->dx;
   surface->offset_y += pending->dy;
@@ -844,6 +849,22 @@ cleanup:
                            G_TRAVERSE_ALL,
                            parent_surface_state_applied,
                            NULL);
+
+  if (had_damage)
+    {
+      MetaWindow *toplevel_window;
+
+      toplevel_window = meta_wayland_surface_get_toplevel_window (surface);
+      if (toplevel_window)
+        {
+          MetaWindowActor *toplevel_window_actor;
+
+          toplevel_window_actor =
+            meta_window_actor_from_window (toplevel_window);
+          if (toplevel_window_actor)
+            meta_window_actor_notify_damaged (toplevel_window_actor);
+        }
+    }
 }
 
 static void