Support 'pathLength' for stroking operations on <path>

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 19 matching lines @@
 #include "core/layout/HitTestResult.h"
 #include "core/layout/LayoutAnalyzer.h"
 #include "core/layout/PointerEventsHitRules.h"
 #include "core/layout/svg/LayoutSVGResourcePaintServer.h"
 #include "core/layout/svg/SVGLayoutSupport.h"
 #include "core/layout/svg/SVGResources.h"
 #include "core/layout/svg/SVGResourcesCache.h"
 #include "core/paint/SVGShapePainter.h"
 #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"
 
 namespace blink {
 
 LayoutSVGShape::LayoutSVGShape(SVGGeometryElement* node)
     : LayoutSVGModelObject(node)
     , m_needsBoundariesUpdate(false) // Default is false, the cached rects are empty from the beginning.
     , m_needsShapeUpdate(true) // Default is true, so we grab a Path object once from SVGGeometryElement.
     , m_needsTransformUpdate(true) // Default is true, so we grab a AffineTransform object once from SVGGeometryElement.
 {
 }
 
 LayoutSVGShape::~LayoutSVGShape()
 {
 }
 
 void LayoutSVGShape::createPath()
 {
     if (!m_path)
         m_path = adoptPtr(new Path());
     *m_path = toSVGGeometryElement(element())->asPath();
     if (m_rareData.get())
         m_rareData->m_cachedNonScalingStrokePath.clear();
 }
 
+float LayoutSVGShape::dashScaleFactor() const
+{
+    if (!isSVGPathElement(element()))
+        return 1;
+    SVGPathElement& pathElement = toSVGPathElement(*element());
+    if (!pathElement.pathLength()->isSpecified())
+        return 1;
+    const SVGComputedStyle& svgStyle = styleRef().svgStyle();
+    float authorPathLength = pathElement.pathLength()->currentValue()->value();
+    if (authorPathLength < 0 || !svgStyle.strokeDashArray()->size())

[f(malita), 2016/02/02 13:44:00]

Is pathLength applicable beyond dashing? I'm assuming if we ever start using it
for something else we could relax this check and just rename the method?

[fs, 2016/02/02 13:47:23]

It applies to <textPath> too I think, so I guess that's where it might turn
up/be needed next.

+        return 1;
+    if (!authorPathLength)
+        return 0;
+    // Since we know this is a <path> element, we also know the source of the
+    // path - the 'd' presentation attribute. Since the StylePath already
+    // caches the computed path length for use, use that here directly.
+    float computedPathLength = svgStyle.d()->length();
+    if (!computedPathLength)
+        return 1;
+    return computedPathLength / authorPathLength;
+}
+
 void LayoutSVGShape::updateShapeFromElement()
 {
     createPath();
 
     m_fillBoundingBox = calculateObjectBoundingBox();
     m_strokeBoundingBox = calculateStrokeBoundingBox();
 }
 
 FloatRect LayoutSVGShape::hitTestStrokeBoundingBox() const
 {
     if (style()->svgStyle().hasStroke())
         return m_strokeBoundingBox;
 
     // Implementation of http://dev.w3.org/fxtf/css-masking-1/#compute-stroke-bounding-box
     // for the <rect> / <ellipse> / <circle> case except that we ignore whether
     // the stroke is none.
 
     FloatRect box = m_fillBoundingBox;
     const float strokeWidth = this->strokeWidth();
     box.inflate(strokeWidth / 2);
     return box;
 }
 
 bool LayoutSVGShape::shapeDependentStrokeContains(const FloatPoint& point)
 {
     ASSERT(m_path);
     StrokeData strokeData;
-    SVGLayoutSupport::applyStrokeStyleToStrokeData(strokeData, styleRef(), *this);
+    SVGLayoutSupport::applyStrokeStyleToStrokeData(strokeData, styleRef(), *this, dashScaleFactor());
 
     if (hasNonScalingStroke()) {
         AffineTransform nonScalingTransform = nonScalingStrokeTransform();
         Path* usePath = nonScalingStrokePath(m_path.get(), nonScalingTransform);
 
         return usePath->strokeContains(nonScalingTransform.mapPoint(point), strokeData);
     }
 
     return m_path->strokeContains(point, strokeData);
 }
@@ skipping 145 matching lines @@
     return path().boundingRect();
 }
 
 FloatRect LayoutSVGShape::calculateStrokeBoundingBox() const
 {
     ASSERT(m_path);
     FloatRect strokeBoundingBox = m_fillBoundingBox;
 
     if (style()->svgStyle().hasStroke()) {
         StrokeData strokeData;
-        SVGLayoutSupport::applyStrokeStyleToStrokeData(strokeData, styleRef(), *this);
+        SVGLayoutSupport::applyStrokeStyleToStrokeData(strokeData, styleRef(), *this, dashScaleFactor());
         if (hasNonScalingStroke()) {
             AffineTransform nonScalingTransform = nonScalingStrokeTransform();
             if (nonScalingTransform.isInvertible()) {
                 Path* usePath = nonScalingStrokePath(m_path.get(), nonScalingTransform);
                 FloatRect strokeBoundingRect = usePath->strokeBoundingRect(strokeData);
                 strokeBoundingRect = nonScalingTransform.inverse().mapRect(strokeBoundingRect);
                 strokeBoundingBox.unite(strokeBoundingRect);
             }
         } else {
             strokeBoundingBox.unite(path().strokeBoundingRect(strokeData));
@@ skipping 25 matching lines @@
 }
 
 LayoutSVGShapeRareData& LayoutSVGShape::ensureRareData() const
 {
     if (!m_rareData)
         m_rareData = adoptPtr(new LayoutSVGShapeRareData());
     return *m_rareData.get();
 }
 
 } // namespace blink