Apply .globalAlpha to SVG-images painted using <canvas> drawImage()

Source/core/svg/graphics/SVGImage.cpp

 /*
  * Copyright (C) 2006 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) Research In Motion Limited 2011. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 229 matching lines @@
 void SVGImage::draw(GraphicsContext* context, const FloatRect& dstRect, const FloatRect& srcRect, CompositeOperator compositeOp, blink::WebBlendMode blendMode)
 {
     if (!m_page)
         return;
 
     GraphicsContextStateSaver stateSaver(*context);
     context->setCompositeOperation(compositeOp, blendMode);
     context->clip(enclosingIntRect(dstRect));
 
     bool compositingRequiresTransparencyLayer = compositeOp != CompositeSourceOver || blendMode != blink::WebBlendModeNormal;
-    if (compositingRequiresTransparencyLayer) {
-        context->beginTransparencyLayer(1);
-        context->setCompositeOperation(CompositeSourceOver, blink::WebBlendModeNormal);
+    bool requiresTransparencyLayer = compositingRequiresTransparencyLayer || context->alpha() < 1;
+    if (requiresTransparencyLayer) {
+        context->beginTransparencyLayer(context->alpha());
+        if (compositingRequiresTransparencyLayer)
+            context->setCompositeOperation(CompositeSourceOver, blink::WebBlendModeNormal);
     }
 
     FloatSize scale(dstRect.width() / srcRect.width(), dstRect.height() / srcRect.height());
 
     // We can only draw the entire frame, clipped to the rect we want. So compute where the top left
     // of the image would be if we were drawing without clipping, and translate accordingly.
     FloatSize topLeftOffset(srcRect.location().x() * scale.width(), srcRect.location().y() * scale.height());
     FloatPoint destOffset = dstRect.location() - topLeftOffset;
 
     context->translate(destOffset.x(), destOffset.y());
     context->scale(scale);
 
     FrameView* view = frameView();
     view->resize(containerSize());
 
     if (view->needsLayout())
         view->layout();
 
     view->paint(context, enclosingIntRect(srcRect));
 
-    if (compositingRequiresTransparencyLayer)
+    if (requiresTransparencyLayer)
         context->endLayer();
 
     stateSaver.restore();
 
     if (imageObserver())
         imageObserver()->didDraw(this);
 }
 
 RenderBox* SVGImage::embeddedContentBox() const
 {
@@ skipping 128 matching lines @@
 
     return m_page;
 }
 
 String SVGImage::filenameExtension() const
 {
     return "svg";
 }
 
 }