[mutter/wip/frame-synchronization: 7/8] MetaWindow: always resize the frame first when we have synchronization

[Owen Taylor <otaylor src gnome org>]

commit 8b2a19b779df376fa912e5b453def62588723cc5
Author: Owen W. Taylor <otaylor fishsoup net>
Date:   Wed Oct 3 23:10:56 2012 -0400

    MetaWindow: always resize the frame first when we have synchronization
    
    Resizing the frame triggers creation of a new backing pixmap for the
    window, so we should do that first before we resize the client window
    and mess up the contents of the old backing pixmap.

 src/core/window.c |   24 ++++++++++++++++++++----
 1 files changed, 20 insertions(+), 4 deletions(-)
---
diff --git a/src/core/window.c b/src/core/window.c
index dd30c13..dbd88b0 100644
--- a/src/core/window.c
+++ b/src/core/window.c
@@ -5003,12 +5003,28 @@ meta_window_move_resize_internal (MetaWindow          *window,
    * efficiently as possible
    */
 
-  /* configure frame first if we grow more than we shrink
+  /* Normally, we configure the frame first depending on whether
+   * we grow the frame more than we shrink. The idea is to avoid
+   * messing up the window contents by having a temporary situation
+   * where the frame is smaller than the window. However, if we're
+   * cooperating with the client to create an atomic frame upate,
+   * and the window is redirected, then we should always update
+   * the frame first, since updating the frame will force a new
+   * backing pixmap to be allocated, and the old backing pixmap
+   * will be left undisturbed for us to paint to the screen until
+   * the client finishes redrawing.
    */
-  size_dx = w - window->rect.width;
-  size_dy = h - window->rect.height;
+  if (window->extended_sync_request_counter)
+    {
+      configure_frame_first = TRUE;
+    }
+  else
+    {
+      size_dx = w - window->rect.width;
+      size_dy = h - window->rect.height;
 
-  configure_frame_first = (size_dx + size_dy >= 0);
+      configure_frame_first = size_dx + size_dy >= 0;
+    }
 
   if (use_static_gravity)
     meta_window_set_gravity (window, StaticGravity);