Extracting the SVG Filter Reference implementation out of the FilterEffectRenderer into its own typ…

Source/core/rendering/FilterEffectRenderer.cpp

Index: Source/core/rendering/FilterEffectRenderer.cpp
diff --git a/Source/core/rendering/FilterEffectRenderer.cpp b/Source/core/rendering/FilterEffectRenderer.cpp
index 6d6ce158d6ef4900745dbe18ee657e6fa76934b6..7ea0e8fac10faf7ada596e899dec63531b1de04f 100644
--- a/Source/core/rendering/FilterEffectRenderer.cpp
+++ b/Source/core/rendering/FilterEffectRenderer.cpp
@@ -53,6 +53,7 @@
 #include "core/loader/cache/CachedSVGDocument.h"
 #include "core/loader/cache/CachedSVGDocumentReference.h"
 #include "core/platform/graphics/filters/SourceAlpha.h"
+#include "core/rendering/svg/ReferenceFilterBuilder.h"
 #include "core/svg/SVGElement.h"
 #include "core/svg/SVGFilterPrimitiveStandardAttributes.h"
 #endif
@@ -115,70 +116,6 @@ GraphicsContext* FilterEffectRenderer::inputContext()
     return sourceImage() ? sourceImage()->context() : 0;
 }
 
-PassRefPtr<FilterEffect> FilterEffectRenderer::buildReferenceFilter(RenderObject* renderer, PassRefPtr<FilterEffect> previousEffect, ReferenceFilterOperation* filterOperation)
-{
-#if ENABLE(SVG)
-    if (!renderer)
-        return 0;
-
-    Document* document = renderer->document();
-    ASSERT(document);
-
-    CachedSVGDocumentReference* cachedSVGDocumentReference = filterOperation->cachedSVGDocumentReference();
-    CachedSVGDocument* cachedSVGDocument = cachedSVGDocumentReference ? cachedSVGDocumentReference->document() : 0;
-
-    // If we have an SVG document, this is an external reference. Otherwise
-    // we look up the referenced node in the current document.
-    if (cachedSVGDocument)
-        document = cachedSVGDocument->document();
-
-    if (!document)
-        return 0;
-
-    Element* filter = document->getElementById(filterOperation->fragment());
-    if (!filter) {
-        // Although we did not find the referenced filter, it might exist later
-        // in the document
-        document->accessSVGExtensions()->addPendingResource(filterOperation->fragment(), toElement(renderer->node()));
-        return 0;
-    }
-
-    RefPtr<FilterEffect> effect;
-
-    // FIXME: Figure out what to do with SourceAlpha. Right now, we're
-    // using the alpha of the original input layer, which is obviously
-    // wrong. We should probably be extracting the alpha from the 
-    // previousEffect, but this requires some more processing.  
-    // This may need a spec clarification.
-    RefPtr<SVGFilterBuilder> builder = SVGFilterBuilder::create(previousEffect, SourceAlpha::create(this));
-
-    for (Node* node = filter->firstChild(); node; node = node->nextSibling()) {
-        if (!node->isSVGElement())
-            continue;
-
-        SVGElement* element = toSVGElement(node);
-        if (!element->isFilterEffect())
-            continue;
-
-        SVGFilterPrimitiveStandardAttributes* effectElement = static_cast<SVGFilterPrimitiveStandardAttributes*>(element);
-
-        effect = effectElement->build(builder.get(), this);
-        if (!effect)
-            continue;
-
-        effectElement->setStandardAttributes(effect.get());
-        builder->add(effectElement->result(), effect);
-        m_effects.append(effect);
-    }
-    return effect;
-#else
-    UNUSED_PARAM(renderer);
-    UNUSED_PARAM(previousEffect);
-    UNUSED_PARAM(filterOperation);
-    return 0;
-#endif
-}
-
 bool FilterEffectRenderer::build(RenderObject* renderer, const FilterOperations& operations)
 {
     m_hasCustomShaderFilter = false;
@@ -186,11 +123,6 @@ bool FilterEffectRenderer::build(RenderObject* renderer, const FilterOperations&
     if (m_hasFilterThatMovesPixels)
         m_outsets = operations.outsets();
     
-    // Keep the old effects on the stack until we've created the new effects.
-    // New FECustomFilters can reuse cached resources from old FECustomFilters.
-    FilterEffectList oldEffects;
-    m_effects.swap(oldEffects);
-
     RefPtr<FilterEffect> previousEffect = m_sourceGraphic;
     for (size_t i = 0; i < operations.operations().size(); ++i) {
         RefPtr<FilterEffect> effect;
@@ -198,8 +130,7 @@ bool FilterEffectRenderer::build(RenderObject* renderer, const FilterOperations&
         switch (filterOperation->getOperationType()) {
         case FilterOperation::REFERENCE: {
             ReferenceFilterOperation* referenceOperation = static_cast<ReferenceFilterOperation*>(filterOperation);
-            effect = buildReferenceFilter(renderer, previousEffect, referenceOperation);
-            referenceOperation->setFilterEffect(effect);
+            effect = ReferenceFilterBuilder::build(this, renderer, previousEffect.get(), referenceOperation);
             break;
         }
         case FilterOperation::GRAYSCALE: {
@@ -355,16 +286,20 @@ bool FilterEffectRenderer::build(RenderObject* renderer, const FilterOperations&
             effect->setClipsToBounds(false);
             effect->setOperatingColorSpace(ColorSpaceDeviceRGB);
             
-            if (filterOperation->getOperationType() != FilterOperation::REFERENCE) {
+            // Reference filters already have a reference to the previousFilter.
+            if (filterOperation->getOperationType() != FilterOperation::REFERENCE)
                 effect->inputEffects().append(previousEffect);
-                m_effects.append(effect);
-            }
+
             previousEffect = effect.release();
         }
     }
 
+    // We need to keep the old effects alive until this point, so that filters like FECustomFilter
+    // can share cached resources across frames.
+    m_lastEffect = previousEffect;
+
     // If we didn't make any effects, tell our caller we are not valid
-    if (!m_effects.size())
+    if (!m_lastEffect.get())
         return false;
 
     setMaxEffectRects(m_sourceDrawingRegion);
@@ -372,6 +307,12 @@ bool FilterEffectRenderer::build(RenderObject* renderer, const FilterOperations&
     return true;
 }
 
+void FilterEffectRenderer::setMaxEffectRects(const FloatRect& effectRect)
+{
+    if (m_lastEffect.get())
+        m_lastEffect->setMaxEffectRectRecursive(effectRect);
+}
+
 bool FilterEffectRenderer::updateBackingStoreRect(const FloatRect& filterRect)
 {
     if (!filterRect.isZero() && isFilterSizeValid(filterRect)) {
@@ -399,9 +340,8 @@ void FilterEffectRenderer::allocateBackingStoreIfNeeded()
 
 void FilterEffectRenderer::clearIntermediateResults()
 {
-    m_sourceGraphic->clearResult();
-    for (size_t i = 0; i < m_effects.size(); ++i)
-        m_effects[i]->clearResult();
+    if (m_lastEffect.get())
+        m_lastEffect->clearResultsRecursive();
 }
 
 void FilterEffectRenderer::apply()