[gtk+/wip/frame-synchronization: 9/19] GdkWindowX11: start off with an odd frame-counter value

[Owen Taylor <otaylor src gnome org>]

commit 40a9f6e6b2fc0e20892b1ea77628f5bbf45ce142
Author: Owen W. Taylor <otaylor fishsoup net>
Date:   Wed Oct 3 20:15:44 2012 -0400

    GdkWindowX11: start off with an odd frame-counter value
    
    By starting with an odd frame counter value, we make the mapping
    and initial paint of the window an atomic operation, avoiding
    any visual artifacts from an unpainted window.
    
    Possible improvement: start the frame when doing gdk_window_show(),
    so that the same improvement occurs for windows that were previously
    shown and are being mapped again.

 gdk/x11/gdkwindow-x11.c |   35 ++++++++++++++++++++++-------------
 1 files changed, 22 insertions(+), 13 deletions(-)
---
diff --git a/gdk/x11/gdkwindow-x11.c b/gdk/x11/gdkwindow-x11.c
index 67ae808..878ac77 100644
--- a/gdk/x11/gdkwindow-x11.c
+++ b/gdk/x11/gdkwindow-x11.c
@@ -225,10 +225,13 @@ gdk_x11_window_begin_frame (GdkWindow *window)
       impl->toplevel->extended_update_counter == None)
     return;
 
-  impl->toplevel->current_counter_value += 1;
-  set_sync_counter(GDK_WINDOW_XDISPLAY (impl->wrapper),
-		   impl->toplevel->extended_update_counter,
-		   impl->toplevel->current_counter_value);
+  if (impl->toplevel->current_counter_value % 2 == 0)
+    {
+      impl->toplevel->current_counter_value += 1;
+      set_sync_counter(GDK_WINDOW_XDISPLAY (impl->wrapper),
+		       impl->toplevel->extended_update_counter,
+		       impl->toplevel->current_counter_value);
+    }
 }
 
 static void
@@ -244,16 +247,19 @@ gdk_x11_window_end_frame (GdkWindow *window)
       impl->toplevel->extended_update_counter == None)
     return;
 
-  impl->toplevel->current_counter_value += 1;
-  set_sync_counter(GDK_WINDOW_XDISPLAY (impl->wrapper),
-		   impl->toplevel->extended_update_counter,
-		   impl->toplevel->current_counter_value);
-
-  if (gdk_x11_screen_supports_net_wm_hint (gdk_window_get_screen (window),
-                                           gdk_atom_intern_static_string ("_NET_WM_FRAME_DRAWN")))
+  if (impl->toplevel->current_counter_value % 2 == 1)
     {
-      impl->toplevel->frame_pending = TRUE;
-      gdk_paint_clock_freeze (gdk_window_get_paint_clock (window));
+      impl->toplevel->current_counter_value += 1;
+      set_sync_counter(GDK_WINDOW_XDISPLAY (impl->wrapper),
+		       impl->toplevel->extended_update_counter,
+		       impl->toplevel->current_counter_value);
+
+      if (gdk_x11_screen_supports_net_wm_hint (gdk_window_get_screen (window),
+					       gdk_atom_intern_static_string ("_NET_WM_FRAME_DRAWN")))
+        {
+          impl->toplevel->frame_pending = TRUE;
+          gdk_paint_clock_freeze (gdk_window_get_paint_clock (window));
+        }
     }
 }
 
@@ -759,6 +765,9 @@ setup_toplevel_window (GdkWindow *window,
     gdk_x11_window_set_user_time (window, GDK_X11_DISPLAY (x11_screen->display)->user_time);
 
   ensure_sync_counter (window);
+
+  /* Start off in a frozen state - we'll finish this when we first paint */
+  gdk_x11_window_begin_frame (window);
 }
 
 static void