[gtk+] wayland: Don't ever try to set surface buffer scale when not supported

[Matthias Clasen <matthiasc src gnome org>]

commit a70b478a5c1bf631dc1053b8711d3f6b64ea77e6
Author: Jonas Ådahl <jadahl gmail com>
Date:   Tue Feb 24 15:00:39 2015 +0800

    wayland: Don't ever try to set surface buffer scale when not supported
    
    If the compositor is too old for handling surface buffer scales, never
    tyr to set change it. This will effectively always leave it to its
    initial state, i.e. 1.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=745076

 gdk/wayland/gdkwindow-wayland.c |   14 ++++++++------
 1 files changed, 8 insertions(+), 6 deletions(-)
---
diff --git a/gdk/wayland/gdkwindow-wayland.c b/gdk/wayland/gdkwindow-wayland.c
index e316a30..76b0729 100644
--- a/gdk/wayland/gdkwindow-wayland.c
+++ b/gdk/wayland/gdkwindow-wayland.c
@@ -195,10 +195,12 @@ _gdk_wayland_screen_create_root_window (GdkScreen *screen,
                                         int        width,
                                         int        height)
 {
+  GdkWaylandDisplay *wayland_display =
+    GDK_WAYLAND_DISPLAY (gdk_screen_get_display (screen));
   GdkWindow *window;
   GdkWindowImplWayland *impl;
 
-  window = _gdk_display_create_window (gdk_screen_get_display (screen));
+  window = _gdk_display_create_window (GDK_DISPLAY (wayland_display));
   window->impl = g_object_new (GDK_TYPE_WINDOW_IMPL_WAYLAND, NULL);
   window->impl_window = window;
   window->visual = gdk_screen_get_system_visual (screen);
@@ -206,10 +208,9 @@ _gdk_wayland_screen_create_root_window (GdkScreen *screen,
   impl = GDK_WINDOW_IMPL_WAYLAND (window->impl);
 
   impl->wrapper = GDK_WINDOW (window);
-  if (gdk_screen_get_n_monitors(screen) > 0)
+  if (wayland_display->compositor_version >= WL_SURFACE_HAS_BUFFER_SCALE &&
+      gdk_screen_get_n_monitors(screen) > 0)
     impl->scale = gdk_screen_get_monitor_scale_factor (screen, 0);
-  else
-    impl->scale = 1;
 
   /* logical 1x1 fake buffer */
   impl->cairo_surface =
@@ -405,7 +406,6 @@ window_update_scale (GdkWindow *window)
   if (wayland_display->compositor_version < WL_SURFACE_HAS_BUFFER_SCALE)
     {
       /* We can't set the scale on this surface */
-      impl->scale = 1;
       return;
     }
 
@@ -446,6 +446,7 @@ _gdk_wayland_display_create_window_impl (GdkDisplay    *display,
                                          GdkWindowAttr *attributes,
                                          gint           attributes_mask)
 {
+  GdkWaylandDisplay *wayland_display = GDK_WAYLAND_DISPLAY (display);
   GdkWindowImplWayland *impl;
   GdkFrameClock *frame_clock;
   const char *title;
@@ -468,7 +469,8 @@ _gdk_wayland_display_create_window_impl (GdkDisplay    *display,
   g_object_ref (window);
 
   /* More likely to be right than just assuming 1 */
-  impl->scale = gdk_screen_get_monitor_scale_factor (screen, 0);
+  if (wayland_display->compositor_version >= WL_SURFACE_HAS_BUFFER_SCALE)
+    impl->scale = gdk_screen_get_monitor_scale_factor (screen, 0);
 
   impl->title = NULL;