Refactor LayoutInline::addOutlineRects to avoid tricky logic to avoid dups

Source/core/layout/LayoutInline.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 1360 matching lines @@
     {
         if (!rect.isEmpty())
             AbsoluteLayoutRectsGeneratorContext::operator()(rect);
     }
 };
 
 } // unnamed namespace
 
 void LayoutInline::addOutlineRects(Vector<LayoutRect>& rects, const LayoutPoint& additionalOffset) const
 {
-    // Add line boxes only if this object is the first object of addOutlineRects().
-    // Otherwise the parent (LayoutBlockFlow or LayoutInline) should have added line box rects
-    // covering those of this object.
-    if (rects.isEmpty()) {

[chrishtr, 2015/08/07 17:08:40]

I don't quite get yet why the new version avoids this duplication problem. Can
you explain in more detail?

[Xianzhu, 2015/08/07 17:18:49]

The duplication problem is about LayoutBlocks with inline children. Previously
the call tree was:
 LayoutBlock::addOutlineRects
 1 add rects for line boxes
 2 LayoutBoxModelObject::addOutlineRectsForNormalChildren
 2.1 LayoutBoxModelObject::addOutlineRectsForDescendant
 2.1.1 LayoutInline::addOutlineRects
At 2.1.1 we checked if the rects is empty.

With this CL, 2.1.1 becomes
LayoutInline::addOutlineRectsForChildrenAndContinuations() which doesn't add
rects for line boxes.

-        AbsoluteLayoutRectsIgnoringEmptyRectsGeneratorContext context(rects, additionalOffset);
-        generateLineBoxRects(context);
-    }
+    AbsoluteLayoutRectsIgnoringEmptyRectsGeneratorContext context(rects, additionalOffset);
+    generateLineBoxRects(context);
+    addOutlineRectsForChildrenAndContinuations(rects, additionalOffset);
+}
+void LayoutInline::addOutlineRectsForChildrenAndContinuations(Vector<LayoutRect>& rects, const LayoutPoint& additionalOffset) const
+{
+    addOutlineRectsForNormalChildren(rects, additionalOffset);
+    addOutlineRectsForContinuations(rects, additionalOffset);
+}
 
-    addOutlineRectsForNormalChildren(rects, additionalOffset);
-
+void LayoutInline::addOutlineRectsForContinuations(Vector<LayoutRect>& rects, const LayoutPoint& additionalOffset) const
+{
     if (LayoutBoxModelObject* continuation = this->continuation()) {
         if (continuation->isInline())
             continuation->addOutlineRects(rects, additionalOffset + (continuation->containingBlock()->location() - containingBlock()->location()));
         else
             continuation->addOutlineRects(rects, additionalOffset + (toLayoutBox(continuation)->location() - containingBlock()->location()));
     }
 }
 
 void LayoutInline::computeSelfHitTestRects(Vector<LayoutRect>& rects, const LayoutPoint& layerOffset) const
 {
@@ skipping 26 matching lines @@
 }
 
 void LayoutInline::invalidateDisplayItemClients(const LayoutBoxModelObject& paintInvalidationContainer) const
 {
     LayoutBoxModelObject::invalidateDisplayItemClients(paintInvalidationContainer);
     for (InlineFlowBox* box = firstLineBox(); box; box = box->nextLineBox())
         paintInvalidationContainer.invalidateDisplayItemClientOnBacking(*box);
 }
 
 } // namespace blink