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.

diff --git a/gdk/gdkframeclockidle.c b/gdk/gdkframeclockidle.c
index 5901c7f6caf825dfd11a6f9dd216c4ebeef54810..b514d651cfc4289aa53524cd7a51e519f2f4b783 100644 (file)
--- 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)