[mutter] wayland: Trigger wl_output updates on actor position changes

[Carlos Garnacho <carlosg src gnome org>]

commit 08e4cb54a80cdbaf01ee1bb7120a8f5dba6e1547
Author: Carlos Garnacho <carlosg gnome org>
Date:   Fri Oct 6 14:53:16 2017 +0200

    wayland: Trigger wl_output updates on actor position changes
    
    Both notify::position on the surface actor and position-changed on
    MetaWindow are listened to, in order to trigger wl_output updates for
    wl_surfaces whenever the surfaces move across them.
    
    Both signals are necessary in order to cater for toplevel and subsurface
    relocations (Because it's the parent window actor what changes position
    in this last case).
    
    Also, shuffle signal disconnection, so each signal goes away with
    the object reference held by MetaWaylandSurface.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=782344

 src/wayland/meta-wayland-surface.c |   75 +++++++++++++++++++++++++++++++----
 1 files changed, 66 insertions(+), 9 deletions(-)
---
diff --git a/src/wayland/meta-wayland-surface.c b/src/wayland/meta-wayland-surface.c
index 6f9df37..7dded19 100644
--- a/src/wayland/meta-wayland-surface.c
+++ b/src/wayland/meta-wayland-surface.c
@@ -182,6 +182,13 @@ static void
 surface_actor_allocation_notify (MetaSurfaceActorWayland *surface_actor,
                                  GParamSpec              *pspec,
                                  MetaWaylandSurface      *surface);
+static void
+surface_actor_position_notify (MetaSurfaceActorWayland *surface_actor,
+                               GParamSpec              *pspec,
+                               MetaWaylandSurface      *surface);
+static void
+window_position_changed (MetaWindow         *window,
+                         MetaWaylandSurface *surface);
 
 static void
 unset_param_value (GParameter *param)
@@ -422,13 +429,6 @@ meta_wayland_surface_destroy_window (MetaWaylandSurface *surface)
       MetaDisplay *display = meta_get_display ();
       guint32 timestamp = meta_display_get_current_time_roundtrip (display);
 
-      g_signal_handlers_disconnect_by_func (surface->surface_actor,
-                                            surface_actor_mapped_notify,
-                                            surface);
-      g_signal_handlers_disconnect_by_func (surface->surface_actor,
-                                            surface_actor_allocation_notify,
-                                            surface);
-
       meta_window_unmanage (surface->window, timestamp);
     }
 
@@ -1272,18 +1272,47 @@ meta_wayland_surface_update_outputs (MetaWaylandSurface *surface)
                         surface);
 }
 
+static void
+meta_wayland_surface_update_outputs_recursively (MetaWaylandSurface *surface)
+{
+  GList *l;
+
+  meta_wayland_surface_update_outputs (surface);
+
+  for (l = surface->subsurfaces; l != NULL; l = l->next)
+    meta_wayland_surface_update_outputs_recursively (l->data);
+}
+
 void
 meta_wayland_surface_set_window (MetaWaylandSurface *surface,
                                  MetaWindow         *window)
 {
   gboolean was_unmapped = surface->window && !window;
 
+  if (surface->window == window)
+    return;
+
+  if (surface->window)
+    {
+      g_signal_handlers_disconnect_by_func (surface->window,
+                                            window_position_changed,
+                                            surface);
+    }
+
   surface->window = window;
   sync_reactive (surface);
   sync_drag_dest_funcs (surface);
 
   if (was_unmapped)
     g_signal_emit (surface, surface_signals[SURFACE_UNMAPPED], 0);
+
+  if (window)
+    {
+      g_signal_connect_object (window,
+                               "position-changed",
+                               G_CALLBACK (window_position_changed),
+                               surface, 0);
+    }
 }
 
 static void
@@ -1320,6 +1349,15 @@ wl_surface_destructor (struct wl_resource *resource)
   if (surface->input_region)
     cairo_region_destroy (surface->input_region);
 
+  g_signal_handlers_disconnect_by_func (surface->surface_actor,
+                                        surface_actor_mapped_notify,
+                                        surface);
+  g_signal_handlers_disconnect_by_func (surface->surface_actor,
+                                        surface_actor_allocation_notify,
+                                        surface);
+  g_signal_handlers_disconnect_by_func (surface->surface_actor,
+                                        surface_actor_position_notify,
+                                        surface);
   g_object_unref (surface->surface_actor);
 
   meta_wayland_compositor_destroy_frame_callbacks (compositor, surface);
@@ -1348,7 +1386,7 @@ surface_actor_mapped_notify (MetaSurfaceActorWayland *surface_actor,
                              GParamSpec              *pspec,
                              MetaWaylandSurface      *surface)
 {
-  meta_wayland_surface_update_outputs (surface);
+  meta_wayland_surface_update_outputs_recursively (surface);
 }
 
 static void
@@ -1356,7 +1394,22 @@ surface_actor_allocation_notify (MetaSurfaceActorWayland *surface_actor,
                                  GParamSpec              *pspec,
                                  MetaWaylandSurface      *surface)
 {
-  meta_wayland_surface_update_outputs (surface);
+  meta_wayland_surface_update_outputs_recursively (surface);
+}
+
+static void
+surface_actor_position_notify (MetaSurfaceActorWayland *surface_actor,
+                               GParamSpec              *pspec,
+                               MetaWaylandSurface      *surface)
+{
+  meta_wayland_surface_update_outputs_recursively (surface);
+}
+
+static void
+window_position_changed (MetaWindow         *window,
+                         MetaWaylandSurface *surface)
+{
+  meta_wayland_surface_update_outputs_recursively (surface);
 }
 
 MetaWaylandSurface *
@@ -1382,6 +1435,10 @@ meta_wayland_surface_create (MetaWaylandCompositor *compositor,
                            G_CALLBACK (surface_actor_allocation_notify),
                            surface, 0);
   g_signal_connect_object (surface->surface_actor,
+                           "notify::position",
+                           G_CALLBACK (surface_actor_position_notify),
+                           surface, 0);
+  g_signal_connect_object (surface->surface_actor,
                            "notify::mapped",
                            G_CALLBACK (surface_actor_mapped_notify),
                            surface, 0);