Update documentation and cleanup impls for localToSVGParentTransform()

third_party/WebKit/Source/core/layout/svg/LayoutSVGRoot.cpp

 /*
  * Copyright (C) 2004, 2005, 2007 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2004, 2005, 2007, 2008, 2009 Rob Buis <buis@kde.org>
  * Copyright (C) 2007 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2009 Google, Inc.
  * Copyright (C) Research In Motion Limited 2011. 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
@@ skipping 324 matching lines @@
   m_localToBorderBoxTransform = svg->viewBoxToViewTransform(
       contentWidth() / scale, contentHeight() / scale);
 
   AffineTransform viewToBorderBoxTransform(
       scale, 0, 0, scale, borderAndPadding.width() + translate.x(),
       borderAndPadding.height() + translate.y());
   viewToBorderBoxTransform.scale(svg->currentScale());
   m_localToBorderBoxTransform.preMultiply(viewToBorderBoxTransform);
 }
 
-const AffineTransform& LayoutSVGRoot::localToSVGParentTransform() const {
-  // Slightly optimized version of m_localToParentTransform =
-  // AffineTransform::translation(x(), y()) * m_localToBorderBoxTransform;
-  m_localToParentTransform = m_localToBorderBoxTransform;
-  if (location().x())
-    m_localToParentTransform.setE(m_localToParentTransform.e() +
-                                  roundToInt(location().x()));
-  if (location().y())
-    m_localToParentTransform.setF(m_localToParentTransform.f() +
-                                  roundToInt(location().y()));
-  return m_localToParentTransform;
+AffineTransform LayoutSVGRoot::localToSVGParentTransform() const {
+  return AffineTransform::translation(roundToInt(location().x()),

[pdr., 2016/11/18 20:35:10]

Wow, these m_localToParentTransform's were not even used.

I'm also a little skeptical of the old comment about optimizing the translation.

[Xianzhu, 2016/11/18 22:19:12]

They seemed to just to satisfy the previous returning type (const
AffineTransform&).

+                                      roundToInt(location().y())) *
+         m_localToBorderBoxTransform;
 }
 
 LayoutRect LayoutSVGRoot::localVisualRect() const {
   // This is an open-coded aggregate of SVGLayoutSupport::localVisualRect
   // and LayoutReplaced::localVisualRect. The reason for this is to optimize/
   // minimize the visual rect when the box is not "decorated" (does not have
   // background/border/etc., see
   // LayoutSVGRootTest.VisualRectMappingWithViewportClipWithoutBorder).
 
   // Return early for any cases where we don't actually paint.
@@ skipping 101 matching lines @@
       if (result.addNodeToListBasedTestResult(node(), locationInContainer,
                                               boundsRect) == StopHitTesting)
         return true;
     }
   }
 
   return false;
 }
 
 }  // namespace blink