[gtk+] gdkframeclock: Loop the layout phase if needed

[Alexander Larsson <alexl src gnome org>]

commit c3bff30b504f80f9c8bc451bb5a73d1b0047b89f
Author: Alexander Larsson <alexl redhat com>
Date:   Wed Apr 24 22:21:06 2013 +0200

    gdkframeclock: Loop the layout phase if needed
    
    In the case where the layout phase queued a layout we don't
    want to progress to the paint phase with invalid allocations, so
    we loop the layout. This shouldn't normally happen, but it may
    happen in some edge cases like if user/wm resizes clash with
    natural window size changes from a gtk widget. This should not
    generally loop though, so we detect this after 4 cycles and
    print a warning.
    
    This was detected because of an issue in GtkWindow where it
    seems to incorrectly handle the case of a user interactive resize.
    It seems gtk_window_move_resize() believes that configure_request_size_changed
    changed due to hitting some corner case so it calls
    gtk_widget_queue_resize_no_redraw(), marking the window as need_alloc
    after the layout phase. This commit fixes the issue, but we should
    also look into if we can fix that.

 gdk/gdkframeclockidle.c |   12 +++++++++++-
 1 files changed, 11 insertions(+), 1 deletions(-)
---
diff --git a/gdk/gdkframeclockidle.c b/gdk/gdkframeclockidle.c
index 5901c7f..b514d65 100644
--- a/gdk/gdkframeclockidle.c
+++ b/gdk/gdkframeclockidle.c
@@ -384,6 +384,7 @@ gdk_frame_clock_paint_idle (void *data)
         case GDK_FRAME_CLOCK_PHASE_LAYOUT:
           if (priv->freeze_count == 0)
             {
+             int iter;
 #ifdef G_ENABLE_DEBUG
               if ((_gdk_debug_flags & GDK_DEBUG_FRAMES) != 0)
                 {
@@ -394,11 +395,20 @@ gdk_frame_clock_paint_idle (void *data)
 #endif /* G_ENABLE_DEBUG */
 
               priv->phase = GDK_FRAME_CLOCK_PHASE_LAYOUT;
-              if (priv->requested & GDK_FRAME_CLOCK_PHASE_LAYOUT)
+             /* We loop in the layout phase, because we don't want to progress
+              * into the paint phase with invalid size allocations. This may
+              * happen in some situation like races between user window
+              * resizes and natural size changes.
+              */
+             iter = 0;
+              while ((priv->requested & GDK_FRAME_CLOCK_PHASE_LAYOUT) &&
+                    priv->freeze_count == 0 && iter++ < 4)
                 {
                   priv->requested &= ~GDK_FRAME_CLOCK_PHASE_LAYOUT;
                   g_signal_emit_by_name (G_OBJECT (clock), "layout");
                 }
+             if (iter == 5)
+               g_warning ("gdk-frame-clock: layout continuously requested, giving up after 4 tries");
             }
         case GDK_FRAME_CLOCK_PHASE_PAINT:
           if (priv->freeze_count == 0)