wayland: Sync surface actor state when changing main monitor

In order to switch to the correct surface actor scale given the monitor
the surface is on, without relying on the client committing a new state
given some other side effect, sync the surface actor state when the main
monitor associated with the corresponding window changed.

https://bugzilla.gnome.org/show_bug.cgi?id=744933

src/compositor/meta-surface-actor-wayland.c

@@ -175,6 +175,23 @@ meta_surface_actor_wayland_sync_state (MetaSurfaceActorWayland *self)
     }
 }
 
+void
+meta_surface_actor_wayland_sync_state_recursive (MetaSurfaceActorWayland *self)
+{
+  MetaWaylandSurface *surface = meta_surface_actor_wayland_get_surface (self);
+  GList *iter;
+
+  meta_surface_actor_wayland_sync_state (self);
+
+  for (iter = surface->subsurfaces; iter != NULL; iter = iter->next)
+    {
+      MetaWaylandSurface *subsurf = iter->data;
+
+      meta_surface_actor_wayland_sync_state_recursive (
+        META_SURFACE_ACTOR_WAYLAND (subsurf->surface_actor));
+    }
+}
+
 static MetaWindow *
 meta_surface_actor_wayland_get_window (MetaSurfaceActor *actor)
 {

src/compositor/meta-surface-actor-wayland.h

@@ -65,6 +65,8 @@ double meta_surface_actor_wayland_get_scale (MetaSurfaceActorWayland *actor);
 
 void meta_surface_actor_wayland_sync_state (MetaSurfaceActorWayland *self);
 
+void meta_surface_actor_wayland_sync_state_recursive (MetaSurfaceActorWayland *self);
+
 G_END_DECLS
 
 #endif /* __META_SURFACE_ACTOR_WAYLAND_H__ */

src/core/window-private.h

@@ -482,6 +482,8 @@ struct _MetaWindowClass
   gboolean (*update_icon)        (MetaWindow       *window,
                                   cairo_surface_t **icon,
                                   cairo_surface_t **mini_icon);
+  void (*main_monitor_changed)   (MetaWindow *window,
+                                  const MetaMonitorInfo *old);
 };
 
 /* These differ from window->has_foo_func in that they consider

src/core/window.c

@@ -761,6 +761,20 @@ meta_window_update_desc (MetaWindow *window)
     window->desc = g_strdup_printf ("0x%lx", window->xwindow);
 }
 
+static void
+meta_window_main_monitor_changed (MetaWindow *window,
+                                  const MetaMonitorInfo *old)
+{
+  META_WINDOW_GET_CLASS (window)->main_monitor_changed (window, old);
+
+  if (old)
+    g_signal_emit_by_name (window->screen, "window-left-monitor",
+                           old->number, window);
+  if (window->monitor)
+    g_signal_emit_by_name (window->screen, "window-entered-monitor",
+                           window->monitor->number, window);
+}
+
 MetaWindow *
 _meta_window_shared_new (MetaDisplay         *display,
                          MetaScreen          *screen,
@@ -1128,7 +1142,7 @@ _meta_window_shared_new (MetaDisplay         *display,
       meta_window_update_struts (window);
     }
 
-  g_signal_emit_by_name (window->screen, "window-entered-monitor", window->monitor->number, window);
+  meta_window_main_monitor_changed (window, NULL);
 
   /* Must add window to stack before doing move/resize, since the
    * window might have fullscreen size (i.e. should have been
@@ -1369,9 +1383,10 @@ meta_window_unmanage (MetaWindow  *window,
 
   if (window->monitor)
     {
-      g_signal_emit_by_name (window->screen, "window-left-monitor",
-                             window->monitor->number, window);
+      const MetaMonitorInfo *old = window->monitor;
+
       window->monitor = NULL;
+      meta_window_main_monitor_changed (window, old);
     }
 
   if (!window->override_redirect)
@@ -3568,9 +3583,7 @@ meta_window_update_monitor (MetaWindow *window,
           window->screen->active_workspace != window->workspace)
         meta_window_change_workspace (window, window->screen->active_workspace);
 
-      if (old)
-        g_signal_emit_by_name (window->screen, "window-left-monitor", old->number, window);
-      g_signal_emit_by_name (window->screen, "window-entered-monitor", window->monitor->number, window);
+      meta_window_main_monitor_changed (window, old);
 
       /* If we're changing monitors, we need to update the has_maximize_func flag,
        * as the working area has changed. */

src/wayland/window-wayland.c

@@ -31,6 +31,7 @@
 #include "boxes-private.h"
 #include "stack-tracker.h"
 #include "meta-wayland-surface.h"
+#include "compositor/meta-surface-actor-wayland.h"
 
 struct _MetaWindowWayland
 {
@@ -270,6 +271,21 @@ meta_window_wayland_move_resize_internal (MetaWindow                *window,
     }
 }
 
+static void
+meta_window_wayland_main_monitor_changed (MetaWindow *window,
+                                          const MetaMonitorInfo *old)
+{
+  MetaWaylandSurface *surface = window->surface;
+
+  if (surface)
+    {
+      MetaSurfaceActorWayland *actor =
+        META_SURFACE_ACTOR_WAYLAND (surface->surface_actor);
+
+      meta_surface_actor_wayland_sync_state_recursive (actor);
+    }
+}
+
 static void
 appears_focused_changed (GObject    *object,
                          GParamSpec *pspec,
@@ -308,6 +324,7 @@ meta_window_wayland_class_init (MetaWindowWaylandClass *klass)
   window_class->grab_op_began = meta_window_wayland_grab_op_began;
   window_class->grab_op_ended = meta_window_wayland_grab_op_ended;
   window_class->move_resize_internal = meta_window_wayland_move_resize_internal;
+  window_class->main_monitor_changed = meta_window_wayland_main_monitor_changed;
 }
 
 MetaWindow *

src/x11/window-x11.c

@@ -1470,6 +1470,12 @@ meta_window_x11_update_icon (MetaWindow       *window,
                           META_MINI_ICON_WIDTH, META_MINI_ICON_HEIGHT);
 }
 
+static void
+meta_window_x11_main_monitor_changed (MetaWindow *window,
+                                      const MetaMonitorInfo *old)
+{
+}
+
 static void
 meta_window_x11_class_init (MetaWindowX11Class *klass)
 {
@@ -1488,6 +1494,7 @@ meta_window_x11_class_init (MetaWindowX11Class *klass)
   window_class->update_struts = meta_window_x11_update_struts;
   window_class->get_default_skip_hints = meta_window_x11_get_default_skip_hints;
   window_class->update_icon = meta_window_x11_update_icon;
+  window_class->main_monitor_changed = meta_window_x11_main_monitor_changed;
 }
 
 void