[gtk/gtk-3-24: 1/2] wayland: Fix xdg-output v3 support

[Matthias Clasen <matthiasc src gnome org>]

commit a1becccd3f2cc67b726f90b91a83e49e4b0aca29
Author: Olivier Fourdan <ofourdan redhat com>
Date:   Tue Sep 3 13:55:00 2019 +0200

    wayland: Fix xdg-output v3 support
    
    The xdg_output.done event is deprecated in xdg-output v3, so clients
    need to rely on the wl_output.done event instead.
    
    However, applying the changes on the fist wl_output.event when using
    xdg-output v3 may lead to an incomplete change, as following xdg-output
    updates may follow.
    
    Make sure we apply xdg-output events on wl_output.done events with
    xdg-output v3.
    
    https://gitlab.gnome.org/GNOME/gtk/issues/2128

 gdk/wayland/gdkscreen-wayland.c | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)
---
diff --git a/gdk/wayland/gdkscreen-wayland.c b/gdk/wayland/gdkscreen-wayland.c
index 8b65cd00fa..76049c39b7 100644
--- a/gdk/wayland/gdkscreen-wayland.c
+++ b/gdk/wayland/gdkscreen-wayland.c
@@ -1445,12 +1445,21 @@ should_update_monitor (GdkWaylandMonitor *monitor)
           monitor->version < OUTPUT_VERSION_WITH_DONE);
 }
 
+static gboolean
+should_expect_xdg_output_done (GdkWaylandMonitor *monitor)
+{
+  GdkDisplay *display = GDK_MONITOR (monitor)->display;
+  GdkWaylandDisplay *display_wayland = GDK_WAYLAND_DISPLAY (display);
+
+  return (monitor_has_xdg_output (monitor) &&
+          display_wayland->xdg_output_version < NO_XDG_OUTPUT_DONE_SINCE_VERSION);
+}
+
 static void
 apply_monitor_change (GdkWaylandMonitor *monitor)
 {
   GdkDisplay *display = GDK_MONITOR (monitor)->display;
   GdkWaylandScreen *screen_wayland = GDK_WAYLAND_SCREEN (gdk_display_get_default_screen (display));
-  GdkWaylandDisplay *display_wayland = GDK_WAYLAND_DISPLAY (display);
 
   GDK_NOTE (MISC,
             g_message ("monitor %d changed position %d %d, size %d %d",
@@ -1462,11 +1471,7 @@ apply_monitor_change (GdkWaylandMonitor *monitor)
   gdk_monitor_set_size (GDK_MONITOR (monitor), monitor->width, monitor->height);
   gdk_monitor_set_connector (GDK_MONITOR (monitor), monitor->name);
   monitor->wl_output_done = FALSE;
-  /* xdg_output v3 marks xdg_output.done as deprecated, so if using
-   * that version, no need to wait for xdg-output.done event.
-   */
-  monitor->xdg_output_done =
-     (display_wayland->xdg_output_version >= NO_XDG_OUTPUT_DONE_SINCE_VERSION);
+  monitor->xdg_output_done = FALSE;
 
   g_signal_emit_by_name (screen_wayland, "monitors-changed");
   update_screen_size (screen_wayland);
@@ -1512,7 +1517,7 @@ xdg_output_handle_done (void                  *data,
             g_message ("handle done xdg-output %d", monitor->id));
 
   monitor->xdg_output_done = TRUE;
-  if (monitor->wl_output_done)
+  if (monitor->wl_output_done && should_expect_xdg_output_done (monitor))
     apply_monitor_change (monitor);
 }
 
@@ -1606,7 +1611,7 @@ output_handle_done (void             *data,
 
   monitor->wl_output_done = TRUE;
 
-  if (!monitor_has_xdg_output (monitor) || monitor->xdg_output_done)
+  if (!should_expect_xdg_output_done (monitor) || monitor->xdg_output_done)
     apply_monitor_change (monitor);
 }