Add support for element blending to SVG

Source/core/rendering/svg/SVGRenderingContext.cpp

 /*
  * Copyright (C) 2007, 2008 Rob Buis <buis@kde.org>
  * Copyright (C) 2007 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2007 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2009 Google, Inc.  All rights reserved.
  * Copyright (C) 2009 Dirk Schulze <krit@webkit.org>
  * Copyright (C) Research In Motion Limited 2009-2010. 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
@@ skipping 84 matching lines @@
 
     RenderStyle* style = m_object->style();
     ASSERT(style);
 
     const SVGRenderStyle* svgStyle = style->svgStyle();
     ASSERT(svgStyle);
 
     // Setup transparency layers before setting up SVG resources!
     bool isRenderingMask = isRenderingMaskImage(m_object);
     float opacity = isRenderingMask ? 1 : style->opacity();
+    BlendMode blendMode = isRenderingMask ? BlendModeNormal : style->blendMode();
     const ShadowData* shadow = svgStyle->shadow();
-    if (opacity < 1 || shadow) {
+    if (opacity < 1 || shadow || blendMode != BlendModeNormal) {
         FloatRect repaintRect = m_object->repaintRectInLocalCoordinates();
 
-        if (opacity < 1) {
+        if (opacity < 1 || blendMode != BlendModeNormal) {
             m_paintInfo->context->clip(repaintRect);
+            if (blendMode != BlendModeNormal) {
+                if (!(m_renderingFlags & RestoreGraphicsContext)) {
+                    m_paintInfo->context->save();
+                    m_renderingFlags |= RestoreGraphicsContext;
+                }
+                m_paintInfo->context->setCompositeOperation(CompositeSourceOver, blendMode);
+            }
             m_paintInfo->context->beginTransparencyLayer(opacity);
             m_renderingFlags |= EndOpacityLayer;
         }
 
         if (shadow) {

[pdr., 2013/07/18 22:24:47]

What happens if we have blending + shadow or blending + opacity? Can you add a
test for this?

             m_paintInfo->context->clip(repaintRect);
             m_paintInfo->context->setShadow(IntSize(roundToInt(shadow->x()), roundToInt(shadow->y())), shadow->blur(), shadow->color());
             m_paintInfo->context->beginTransparencyLayer(1);
             m_renderingFlags |= EndShadowLayer;
         }
     }
 
     ClipPathOperation* clipPathOperation = style->clipPath();
     if (clipPathOperation && clipPathOperation->getOperationType() == ClipPathOperation::SHAPE) {
         ShapeClipPathOperation* clipPath = static_cast<ShapeClipPathOperation*>(clipPathOperation);
@@ skipping 215 matching lines @@
             toRenderSVGImage(m_object)->paintForeground(bufferedInfo);
         } else
             return false;
     }
 
     m_paintInfo->context->drawImageBuffer(imageBuffer.get(), boundingBox);
     return true;
 }
 
 }