Optimize layout/repaint on FrameView resize

Source/core/rendering/RenderObject.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  *           (C) 2004 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 1604 matching lines @@
 }
 
 void RenderObject::repaintOverflowIfNeeded()
 {
     if (shouldRepaintOverflow())
         repaintOverflow();
 }
 
 bool RenderObject::checkForRepaint() const
 {
-    return !document().view()->needsFullRepaint() && !hasLayer() && everHadLayout();

[dsinclair, 2014/03/20 10:41:41]

Won't this end up triggering more invalidations? Previously if the view was
marked as doing a full repaint we'd skip issuing invalidations for children.
With this change, we'll always issue the child invalidations even if the full
renderView will be invalidated.

Should it be checking something like the needsRepaintLayout flag instead?

[Xianzhu, 2014/03/20 17:47:43]

It seems hard to weigh between full repaint and child repaints in
FrameView::layout(). In some cases we can be sure that full repaint is better
and mark full repaint. For other cases, perhaps we can fall back to full repaint
when number or area of child repaints exceeds some threshold during layout.
Good idea. I think this would help improve the situation. Would like to consider
it in some later change.

+    return !hasLayer() && everHadLayout();
 }
 
 bool RenderObject::checkForRepaintDuringLayout() const
 {
     return !RuntimeEnabledFeatures::repaintAfterLayoutEnabled() && checkForRepaint();
 }
 
 LayoutRect RenderObject::rectWithOutlineForRepaint(const RenderLayerModelObject* repaintContainer, LayoutUnit outlineWidth) const
 {
     LayoutRect r(clippedOverflowRectForRepaint(repaintContainer));
@@ skipping 1716 matching lines @@
 {
     if (object1) {
         const WebCore::RenderObject* root = object1;
         while (root->parent())
             root = root->parent();
         root->showRenderTreeAndMark(object1, "*", object2, "-", 0);
     }
 }
 
 #endif