wayland/surface: Move subsurface synchronization logic to role

It's an implementation detail of subsurfaces when to cache state
and when not to, so move that logic to the subsurface role
implementation.

https://gitlab.gnome.org/GNOME/mutter/merge_requests/907

src/wayland/meta-wayland-subsurface.c

@@ -112,6 +112,12 @@ is_sibling (MetaWaylandSurface *surface,
     return FALSE;
 }
 
+static gboolean
+is_surface_effectively_synchronized (MetaWaylandSurface *surface)
+{
+  return meta_wayland_surface_should_cache_state (surface);
+}
+
 void
 meta_wayland_subsurface_parent_state_applied (MetaWaylandSubsurface *subsurface)
 {
@@ -182,7 +188,7 @@ meta_wayland_subsurface_parent_state_applied (MetaWaylandSubsurface *subsurface)
         meta_window_actor_wayland_rebuild_surface_tree (window_actor);
     }
 
-  if (meta_wayland_surface_is_effectively_synchronized (surface))
+  if (is_surface_effectively_synchronized (surface))
     meta_wayland_surface_apply_pending_state (surface, surface->sub.pending);
 
   meta_wayland_actor_surface_sync_actor_state (actor_surface);
@@ -240,6 +246,23 @@ meta_wayland_subsurface_get_toplevel (MetaWaylandSurfaceRole *surface_role)
     return NULL;
 }
 
+static gboolean
+meta_wayland_subsurface_should_cache_state (MetaWaylandSurfaceRole *surface_role)
+{
+  MetaWaylandSurface *surface =
+    meta_wayland_surface_role_get_surface (surface_role);
+  MetaWaylandSurface *parent;
+
+  if (surface->sub.synchronous)
+    return TRUE;
+
+  parent = surface->sub.parent;
+  if (parent)
+    return meta_wayland_surface_should_cache_state (parent);
+
+  return TRUE;
+}
+
 static double
 meta_wayland_subsurface_get_geometry_scale (MetaWaylandActorSurface *actor_surface)
 {
@@ -294,6 +317,7 @@ meta_wayland_subsurface_class_init (MetaWaylandSubsurfaceClass *klass)
     META_WAYLAND_ACTOR_SURFACE_CLASS (klass);
 
   surface_role_class->get_toplevel = meta_wayland_subsurface_get_toplevel;
+  surface_role_class->should_cache_state = meta_wayland_subsurface_should_cache_state;
 
   actor_surface_class->get_geometry_scale =
     meta_wayland_subsurface_get_geometry_scale;
@@ -456,12 +480,11 @@ wl_subsurface_set_desync (struct wl_client   *client,
   MetaWaylandSurface *surface = wl_resource_get_user_data (resource);
   gboolean was_effectively_synchronized;
 
-  was_effectively_synchronized =
-    meta_wayland_surface_is_effectively_synchronized (surface);
+  was_effectively_synchronized = is_surface_effectively_synchronized (surface);
   surface->sub.synchronous = FALSE;
 
   if (was_effectively_synchronized &&
-      !meta_wayland_surface_is_effectively_synchronized (surface))
+      !is_surface_effectively_synchronized (surface))
     meta_wayland_surface_apply_pending_state (surface, surface->sub.pending);
 }
 

src/wayland/meta-wayland-surface.c

@@ -593,35 +593,6 @@ meta_wayland_pending_state_class_init (MetaWaylandPendingStateClass *klass)
                   G_TYPE_NONE, 0);
 }
 
-/* A non-subsurface is always desynchronized.
- *
- * A subsurface is effectively synchronized if either its parent is
- * synchronized or itself is in synchronized mode. */
-gboolean
-meta_wayland_surface_is_effectively_synchronized (MetaWaylandSurface *surface)
-{
-  if (surface->wl_subsurface == NULL)
-    {
-      return FALSE;
-    }
-  else
-    {
-      if (surface->sub.synchronous)
-        {
-          return TRUE;
-        }
-      else
-        {
-          MetaWaylandSurface *parent = surface->sub.parent;
-
-          if (parent)
-            return meta_wayland_surface_is_effectively_synchronized (parent);
-
-          return TRUE;
-        }
-    }
-}
-
 static void
 parent_surface_state_applied (GNode    *subsurface_node,
                               gpointer  user_data)
@@ -864,7 +835,7 @@ meta_wayland_surface_commit (MetaWaylandSurface *surface)
    *  2) Its mode changes from synchronized to desynchronized and its parent
    *     surface is in effective desynchronized mode.
    */
-  if (meta_wayland_surface_is_effectively_synchronized (surface))
+  if (meta_wayland_surface_should_cache_state (surface))
     merge_pending_state (surface->pending, surface->sub.pending);
   else
     meta_wayland_surface_apply_pending_state (surface, surface->pending);
@@ -1846,6 +1817,27 @@ meta_wayland_surface_role_get_toplevel (MetaWaylandSurfaceRole *surface_role)
     return NULL;
 }
 
+static gboolean
+meta_wayland_surface_role_should_cache_state (MetaWaylandSurfaceRole *surface_role)
+{
+  MetaWaylandSurfaceRoleClass *klass;
+
+  klass = META_WAYLAND_SURFACE_ROLE_GET_CLASS (surface_role);
+  if (klass->should_cache_state)
+    return klass->should_cache_state (surface_role);
+  else
+    return FALSE;
+}
+
+gboolean
+meta_wayland_surface_should_cache_state (MetaWaylandSurface *surface)
+{
+  if (!surface->role)
+    return FALSE;
+
+  return meta_wayland_surface_role_should_cache_state (surface->role);
+}
+
 MetaWaylandSurface *
 meta_wayland_surface_role_get_surface (MetaWaylandSurfaceRole *role)
 {

src/wayland/meta-wayland-surface.h

@@ -63,6 +63,7 @@ struct _MetaWaylandSurfaceRoleClass
   gboolean (*is_on_logical_monitor) (MetaWaylandSurfaceRole *surface_role,
                                      MetaLogicalMonitor     *logical_monitor);
   MetaWaylandSurface * (*get_toplevel) (MetaWaylandSurfaceRole *surface_role);
+  gboolean (*should_cache_state) (MetaWaylandSurfaceRole *surface_role);
 };
 
 struct _MetaWaylandSerial {
@@ -273,6 +274,8 @@ void                meta_wayland_surface_update_outputs (MetaWaylandSurface *sur
 
 MetaWaylandSurface *meta_wayland_surface_get_toplevel (MetaWaylandSurface *surface);
 
+gboolean            meta_wayland_surface_should_cache_state (MetaWaylandSurface *surface);
+
 MetaWindow *        meta_wayland_surface_get_toplevel_window (MetaWaylandSurface *surface);
 
 void                meta_wayland_surface_cache_pending_frame_callbacks (MetaWaylandSurface      *surface,