ImageBuffer-less SVG masking and clipping.

Source/core/rendering/RenderLayer.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
  *   Randall Jesup <rjesup@wgate.com>
@@ skipping 3656 matching lines @@
 
     LayoutPoint offsetFromRoot;
     convertToLayerCoords(paintingInfo.rootLayer, offsetFromRoot);
 
     IntRect rootRelativeBounds;
     bool rootRelativeBoundsComputed = false;
 
     // Apply clip-path to context.
     bool hasClipPath = false;
     RenderStyle* style = renderer()->style();
+    RenderSVGResourceClipper* resourceClipper = 0;
     if (renderer()->hasClipPath() && !context->paintingDisabled() && style) {
         ASSERT(style->clipPath());
         if (style->clipPath()->getOperationType() == ClipPathOperation::SHAPE) {
             hasClipPath = true;
             context->save();
             ShapeClipPathOperation* clipPath = static_cast<ShapeClipPathOperation*>(style->clipPath());
 
             if (!rootRelativeBoundsComputed) {
                 rootRelativeBounds = calculateLayerBounds(paintingInfo.rootLayer, &offsetFromRoot, 0);
                 rootRelativeBoundsComputed = true;
             }
 
             context->clipPath(clipPath->path(rootRelativeBounds), clipPath->windRule());
         } else if (style->clipPath()->getOperationType() == ClipPathOperation::REFERENCE) {
             ReferenceClipPathOperation* referenceClipPathOperation = static_cast<ReferenceClipPathOperation*>(style->clipPath());
             Document* document = renderer()->document();
             // FIXME: It doesn't work with forward or external SVG references (https://bugs.webkit.org/show_bug.cgi?id=90405)
             Element* element = document ? document->getElementById(referenceClipPathOperation->fragment()) : 0;
             if (element && element->hasTagName(SVGNames::clipPathTag) && element->renderer()) {
                 if (!rootRelativeBoundsComputed) {
                     rootRelativeBounds = calculateLayerBounds(paintingInfo.rootLayer, &offsetFromRoot, 0);
                     rootRelativeBoundsComputed = true;
                 }
 
                 // FIXME: This should use a safer cast such as toRenderSVGResourceContainer().
-                static_cast<RenderSVGResourceClipper*>(element->renderer())->applyClippingToContext(renderer(), rootRelativeBounds, paintingInfo.paintDirtyRect, context);
+                resourceClipper = static_cast<RenderSVGResourceClipper*>(element->renderer());
+                if (!resourceClipper->applyClippingToContext(renderer(), rootRelativeBounds, paintingInfo.paintDirtyRect, context)) {
+                    // No need to post-apply the clipper if this failed.
+                    resourceClipper = 0;
+                }
             }
         }
     }
 
     LayerPaintingInfo localPaintingInfo(paintingInfo);
     FilterEffectRendererHelper filterPainter(filterRenderer() && paintsWithFilters());
     if (filterPainter.haveFilterEffect() && !context->paintingDisabled()) {
         RenderLayerFilterInfo* filterInfo = this->filterInfo();
         ASSERT(filterInfo);
         LayoutRect filterRepaintRect = filterInfo->dirtySourceRect();
@@ skipping 105 matching lines @@
     if (shouldPaintMask)
         paintMaskForFragments(layerFragments, context, localPaintingInfo, paintingRootForRenderer);
 
     // End our transparency layer
     if (haveTransparency && m_usedTransparency && !m_paintingInsideReflection) {
         context->endTransparencyLayer();
         context->restore();
         m_usedTransparency = false;
     }
 
+    if (resourceClipper)
+        resourceClipper->postApplyResource(renderer(), context, ApplyToDefaultMode, 0, 0);
+
     if (hasClipPath)
         context->restore();
 }
 
 void RenderLayer::paintLayerByApplyingTransform(GraphicsContext* context, const LayerPaintingInfo& paintingInfo, PaintLayerFlags paintFlags, const LayoutPoint& translationOffset)
 {
     // This involves subtracting out the position of the layer in our current coordinate space, but preserving
     // the accumulated error for sub-pixel layout.
     LayoutPoint delta;
     convertToLayerCoords(paintingInfo.rootLayer, delta);
@@ skipping 2629 matching lines @@
     }
 }
 
 void showLayerTree(const WebCore::RenderObject* renderer)
 {
     if (!renderer)
         return;
     showLayerTree(renderer->enclosingLayer());
 }
 #endif