Introduce Layout*::adjustVisualRectForRasterEffects and use it for SVG hairlines.

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

 /*
  * Copyright (C) 2004, 2005, 2007 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2004, 2005, 2008 Rob Buis <buis@kde.org>
  * Copyright (C) 2005, 2007 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2009 Google, Inc.
  * Copyright (C) 2009 Dirk Schulze <krit@webkit.org>
  * Copyright (C) Research In Motion Limited 2010. All rights reserved.
  * Copyright (C) 2009 Jeff Schiller <codedread@gmail.com>
  * Copyright (C) 2011 Renata Hodovan <reni@webkit.org>
  * Copyright (C) 2011 University of Szeged
@@ skipping 27 matching lines @@
 #include "core/svg/SVGGeometryElement.h"
 #include "core/svg/SVGLengthContext.h"
 #include "core/svg/SVGPathElement.h"
 #include "platform/geometry/FloatPoint.h"
 #include "platform/graphics/StrokeData.h"
 #include "wtf/MathExtras.h"
 #include "wtf/PtrUtil.h"
 
 namespace blink {
 
+void LayoutSVGShape::adjustVisualRectForRasterEffects(
+    LayoutRect& visualRect) const {
+  // Account for raster expansions due to SVG stroke hairline raster effects.
+  if (styleRef().svgStyle().hasVisibleStroke()) {

[Xianzhu, 2016/10/24 16:17:30]

We should add !visualRect.isEmpty() to avoid inflating an empty rect to
non-empty.

[chrishtr, 2016/10/31 20:52:01]

Verified done by wangxianzhu.

+    float pad = 0.5f;

[Xianzhu, 2016/10/24 16:17:30]

Nit: s/float/LayoutUnit/

[chrishtr, 2016/10/31 20:52:01]

Verified done by wangxianzhu.

+    if (styleRef().svgStyle().capStyle() != ButtCap)
+      pad += 0.5f;
+    visualRect.inflate(LayoutUnit(pad));
+  }
+}
+
 LayoutSVGShape::LayoutSVGShape(SVGGeometryElement* node)
     : LayoutSVGModelObject(node),
       // Default is false, the cached rects are empty from the beginning.
       m_needsBoundariesUpdate(false),
       // Default is true, so we grab a Path object once from SVGGeometryElement.
       m_needsShapeUpdate(true),
       // Default is true, so we grab a AffineTransform object once from
       // SVGGeometryElement.
       m_needsTransformUpdate(true) {}
 
@@ skipping 258 matching lines @@
   return lengthContext.valueForLength(style()->svgStyle().strokeWidth());
 }
 
 LayoutSVGShapeRareData& LayoutSVGShape::ensureRareData() const {
   if (!m_rareData)
     m_rareData = wrapUnique(new LayoutSVGShapeRareData());
   return *m_rareData.get();
 }
 
 }  // namespace blink