core: Avoid setting up frames on fullscreen windows

Ensure we preserve the fast zero-copy paths in Xwayland fullscreen
windows, instead of maybe rendering the client surface on top of the
frame surface, and providing the latter to the compositor.

To achieve this, additionally synchronize frame state when
recalculating features (e.g. after fullscreen/unfullscreen), and
account for this new condition when creating or destroying frames.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2797>

3 files changed, 17 insertions, 7 deletions

diff --git a/src/core/frame.c b/src/core/frame.c
index 9b08d0727..c2f0b43b1 100644
--- a/src/core/frame.c
+++ b/src/core/frame.c
@@ -45,6 +45,9 @@ meta_window_ensure_frame (MetaWindow *window)
   MetaX11Display *x11_display = window->display->x11_display;
   unsigned long data[1] = { 1 };
 
+  if (window->frame)
+    return;
+
   meta_x11_error_trap_push (x11_display);
 
   XChangeProperty (x11_display->xdisplay,
diff --git a/src/core/window.c b/src/core/window.c
index c94e70e47..03dd0506a 100644
--- a/src/core/window.c
+++ b/src/core/window.c
@@ -851,7 +851,7 @@ client_window_should_be_mapped (MetaWindow *window)
 #endif
 
   if (window->client_type == META_WINDOW_CLIENT_TYPE_X11 &&
-      window->decorated && !window->frame)
+      window->decorated && !window->fullscreen && !window->frame)
     return FALSE;
 
   return TRUE;
@@ -1705,7 +1705,7 @@ meta_window_should_be_showing (MetaWindow  *window)
 #endif
 
   if (window->client_type == META_WINDOW_CLIENT_TYPE_X11 &&
-      window->decorated && !window->frame)
+      window->decorated && !window->fullscreen && !window->frame)
     return FALSE;
 
   /* Windows should be showing if they're located on the
@@ -5325,6 +5325,15 @@ meta_window_update_struts (MetaWindow *window)
 }
 
 static void
+sync_needs_frame (MetaWindow *window)
+{
+  if (window->decorated && !window->fullscreen)
+    meta_window_ensure_frame (window);
+  else
+    meta_window_destroy_frame (window);
+}
+
+static void
 meta_window_type_changed (MetaWindow *window)
 {
   gboolean old_decorated = window->decorated;
@@ -5337,10 +5346,7 @@ meta_window_type_changed (MetaWindow *window)
     set_net_wm_state (window);
 
   /* Update frame */
-  if (window->decorated)
-    meta_window_ensure_frame (window);
-  else
-    meta_window_destroy_frame (window);
+  sync_needs_frame (window);
 
   /* update stacking constraints */
   meta_window_update_layer (window);
@@ -5611,6 +5617,7 @@ meta_window_recalc_features (MetaWindow *window)
   if (window->has_resize_func != old_has_resize_func)
     g_object_notify_by_pspec (G_OBJECT (window), obj_props[PROP_RESIZEABLE]);
 
+  sync_needs_frame (window);
   meta_window_frame_size_changed (window);
 }
 
diff --git a/src/x11/window-x11.c b/src/x11/window-x11.c
index 3b3ea502f..0e7b7fd2f 100644
--- a/src/x11/window-x11.c
+++ b/src/x11/window-x11.c
@@ -562,7 +562,7 @@ meta_window_x11_manage (MetaWindow *window)
   if (!window->override_redirect)
     update_sm_hints (window); /* must come after transient_for */
 
-  if (window->decorated)
+  if (window->decorated && !window->fullscreen)
     meta_window_ensure_frame (window);
   else
     meta_window_x11_initialize_state (window);