[SVG] Re-enable experimental PathOpsSVGClipping support

Source/core/layout/svg/LayoutSVGResourceClipper.cpp

 /*
  * Copyright (C) 2004, 2005, 2007, 2008 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Rob Buis <buis@kde.org>
  * Copyright (C) Research In Motion Limited 2009-2010. All rights reserved.
  * Copyright (C) 2011 Dirk Schulze <krit@webkit.org>
  *
  * 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 22 matching lines @@
 #include "core/paint/PaintInfo.h"
 #include "core/paint/TransformRecorder.h"
 #include "core/svg/SVGUseElement.h"
 #include "platform/RuntimeEnabledFeatures.h"
 #include "platform/graphics/paint/ClipPathDisplayItem.h"
 #include "platform/graphics/paint/CompositingDisplayItem.h"
 #include "platform/graphics/paint/DisplayItemList.h"
 #include "platform/graphics/paint/DrawingDisplayItem.h"
 #include "platform/graphics/paint/SkPictureBuilder.h"
 #include "third_party/skia/include/core/SkPicture.h"
+#include "third_party/skia/include/pathops/SkPathOps.h"
 
 namespace blink {
 
 LayoutSVGResourceClipper::LayoutSVGResourceClipper(SVGClipPathElement* node)
     : LayoutSVGResourceContainer(node)
     , m_inClipExpansion(false)
 {
 }
 
 LayoutSVGResourceClipper::~LayoutSVGResourceClipper()
@@ skipping 13 matching lines @@
     markClientForInvalidation(client, markForInvalidation ? BoundariesInvalidation : ParentOnlyInvalidation);
 }
 
 bool LayoutSVGResourceClipper::tryPathOnlyClipping(const LayoutObject& layoutObject, GraphicsContext* context,
     const AffineTransform& animatedLocalTransform, const FloatRect& objectBoundingBox) {
     // If the current clip-path gets clipped itself, we have to fallback to masking.
     if (!style()->svgStyle().clipperResource().isEmpty())
         return false;
 
     Path clipPath;
+    bool usingBuilder = false;
+    SkOpBuilder clipPathBuilder;
 
     for (SVGElement* childElement = Traversal<SVGElement>::firstChild(*element()); childElement; childElement = Traversal<SVGElement>::nextSibling(*childElement)) {
         LayoutObject* childLayoutObject = childElement->layoutObject();
         if (!childLayoutObject)
             continue;
         // Only shapes or paths are supported for direct clipping. We need to fallback to masking for texts.
         if (childLayoutObject->isSVGText())
             return false;
         if (!childElement->isSVGGraphicsElement())
             continue;
         SVGGraphicsElement* styled = toSVGGraphicsElement(childElement);
         const ComputedStyle* style = childLayoutObject->style();
         if (!style || style->display() == NONE || style->visibility() != VISIBLE)
             continue;
         const SVGComputedStyle& svgStyle = style->svgStyle();
         // Current shape in clip-path gets clipped too. Fallback to masking.
         if (!svgStyle.clipperResource().isEmpty())
             return false;
 
+        // First clip shape.
         if (clipPath.isEmpty()) {
-            // First clip shape.
             styled->toClipPath(clipPath);
+
             continue;
         }
 
-        if (RuntimeEnabledFeatures::pathOpsSVGClippingEnabled()) {
-            // Attempt to generate a combined clip path, fall back to masking if not possible.
-            Path subPath;
-            styled->toClipPath(subPath);
-            if (!clipPath.unionPath(subPath))
-                return false;
-        } else {
+        // Multiple shapes require PathOps.
+        if (!RuntimeEnabledFeatures::pathOpsSVGClippingEnabled())
             return false;
+
+        // Second clip shape => start using the builder.
+        if (!usingBuilder) {
+            clipPathBuilder.add(clipPath.skPath(), kUnion_SkPathOp);
+            usingBuilder = true;
         }
+
+        Path subPath;
+        styled->toClipPath(subPath);
+        clipPathBuilder.add(subPath.skPath(), kUnion_SkPathOp);
+    }
+
+    if (usingBuilder) {
+        SkPath resolvedPath;
+        clipPathBuilder.resolve(&resolvedPath);
+        clipPath = resolvedPath;
     }
 
     // We are able to represent the clip as a path. Continue with direct clipping,
     // and transform the content to userspace if necessary.
     if (clipPathUnits() == SVGUnitTypes::SVG_UNIT_TYPE_OBJECTBOUNDINGBOX) {
         AffineTransform transform;
         transform.translate(objectBoundingBox.x(), objectBoundingBox.y());
         transform.scaleNonUniform(objectBoundingBox.width(), objectBoundingBox.height());
         clipPath.transform(transform);
     }
@@ skipping 135 matching lines @@
         AffineTransform transform;
         transform.translate(objectBoundingBox.x(), objectBoundingBox.y());
         transform.scaleNonUniform(objectBoundingBox.width(), objectBoundingBox.height());
         return transform.mapRect(m_clipBoundaries);
     }
 
     return m_clipBoundaries;
 }
 
 }