Optimize outline paint invalidation

third_party/WebKit/Source/core/layout/LayoutBox.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2005 Allan Sandfeld Jensen (kde@carewolf.com)
  *           (C) 2005, 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc.
  *               All rights reserved.
  * Copyright (C) 2013 Adobe Systems Incorporated. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 4795 matching lines @@
 void LayoutBox::addVisualEffectOverflow() {
   if (!style()->hasVisualOverflowingEffect())
     return;
 
   // Add in the final overflow with shadows, outsets and outline combined.
   LayoutRect visualEffectOverflow = borderBoxRect();
   visualEffectOverflow.expand(computeVisualEffectOverflowOutsets());
   addSelfVisualOverflow(visualEffectOverflow);
 }
 
-LayoutRectOutsets LayoutBox::computeVisualEffectOverflowOutsets() const {
+LayoutRectOutsets LayoutBox::computeVisualEffectOverflowOutsets() {
   ASSERT(style()->hasVisualOverflowingEffect());
 
   LayoutUnit top;
   LayoutUnit right;
   LayoutUnit bottom;
   LayoutUnit left;
 
   if (const ShadowList* boxShadow = style()->boxShadow()) {
     // FIXME: Use LayoutUnit edge outsets, and then simplify this.
     FloatRectOutsets outsets = boxShadow->rectOutsetsIncludingOriginal();
@@ skipping 15 matching lines @@
   // block direction.
   if (UNLIKELY(hasFlippedBlocksWritingMode()))
     std::swap(left, right);
 
   if (style()->hasOutline()) {
     Vector<LayoutRect> outlineRects;
     // The result rects are in coordinates of this object's border box.
     addOutlineRects(outlineRects, LayoutPoint(),
                     outlineRectsShouldIncludeBlockVisualOverflow());
     LayoutRect rect = unionRectEvenIfEmpty(outlineRects);
+    setOutlineMayBeAffectedByDescendants(rect.size() != size());
+
     int outlineOutset = style()->outlineOutsetExtent();
     top = std::max(top, -rect.y() + outlineOutset);
     right = std::max(right, rect.maxX() - size().width() + outlineOutset);
     bottom = std::max(bottom, rect.maxY() - size().height() + outlineOutset);
     left = std::max(left, -rect.x() + outlineOutset);
   }
 
   return LayoutRectOutsets(top, right, bottom, left);
 }
 
@@ skipping 832 matching lines @@
     block->adjustChildDebugRect(rect);
 
   return rect;
 }
 
 bool LayoutBox::shouldClipOverflow() const {
   return hasOverflowClip() || styleRef().containsPaint() || hasControlClip();
 }
 
 }  // namespace blink