Put SVGResourceContainer subtypes into their own property trees.

third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/paint/PaintPropertyTreeBuilder.h"
 
 #include <memory>
 #include "core/dom/DOMNodeIds.h"
 #include "core/frame/FrameView.h"
 #include "core/frame/LocalFrame.h"
 #include "core/frame/Settings.h"
 #include "core/layout/LayoutInline.h"
 #include "core/layout/LayoutView.h"
 #include "core/layout/compositing/CompositingReasonFinder.h"
 #include "core/layout/svg/LayoutSVGResourceMasker.h"
 #include "core/layout/svg/LayoutSVGRoot.h"
 #include "core/layout/svg/SVGLayoutSupport.h"
 #include "core/layout/svg/SVGResources.h"
 #include "core/layout/svg/SVGResourcesCache.h"
 #include "core/paint/FindPropertiesNeedingUpdate.h"
 #include "core/paint/ObjectPaintProperties.h"
 #include "core/paint/PaintLayer.h"
 #include "core/paint/SVGRootPainter.h"
 #include "platform/transforms/TransformationMatrix.h"
 #include "wtf/PtrUtil.h"
 
 namespace blink {
 
-void PaintPropertyTreeBuilder::setupInitialContext(
+void PaintPropertyTreeBuilder::resetToRootContext(
     PaintPropertyTreeBuilderContext& context) {
   context.current.clip = context.absolutePosition.clip =
       context.fixedPosition.clip = ClipPaintPropertyNode::root();
   context.currentEffect = EffectPaintPropertyNode::root();
   context.inputClipOfCurrentEffect = ClipPaintPropertyNode::root();
   context.current.transform = context.absolutePosition.transform =
       context.fixedPosition.transform = TransformPaintPropertyNode::root();
   context.current.scroll = context.absolutePosition.scroll =
       context.fixedPosition.scroll = ScrollPaintPropertyNode::root();
 }
 
+void PaintPropertyTreeBuilder::setupInitialContext(
+    PaintPropertyTreeBuilderContext& context) {
+  resetToRootContext(context);
+}
+
 // True if a new property was created, false if an existing one was updated.
 static bool updatePreTranslation(
     FrameView& frameView,
     PassRefPtr<const TransformPaintPropertyNode> parent,
     const TransformationMatrix& matrix,
     const FloatPoint3D& origin) {
   DCHECK(!RuntimeEnabledFeatures::rootLayerScrollingEnabled());
   if (auto* existingPreTranslation = frameView.preTranslation()) {
     existingPreTranslation->update(std::move(parent), matrix, origin);
     return false;
@@ skipping 1032 matching lines @@
       // frame rect, so force a property update if it changes. TODO(pdr): We
       // only need to update properties if there are relative lengths.
       box.styleRef().hasTransform() || box.styleRef().hasPerspective() ||
       boxGeneratesPropertyNodesForMaskAndClipPath)
     box.getMutableForPainting().setNeedsPaintPropertyUpdate();
 }
 
 void PaintPropertyTreeBuilder::updatePropertiesForSelf(
     const LayoutObject& object,
     PaintPropertyTreeBuilderContext& context) {
+  if (object.isSVGResourceContainer()) {
+    // SVG resources are painted within one or more other locations in the
+    // SVG during paint, and hence have their own independent paint property
+    // trees.
+    resetToRootContext(context);

[pdr., 2017/03/21 22:26:22]

This re-use of setupInitialContext is clever. I think we will need to make it a
little more robust for your usecase though. For example, paintOffset,
shouldFlattenInheritedTransform, containerForAbsolutePosition, and
paintOffsetForFloat need to be reset.

[chrishtr, 2017/03/21 23:29:57]

Changed to reuse the constructor, which will get these for free.

+  }
+
   // This is not in FindObjectPropertiesNeedingUpdateScope because paint offset
   // can change without needsPaintPropertyUpdate.
   updateForObjectLocationAndSize(object, context);
 
 #if DCHECK_IS_ON()
   FindObjectPropertiesNeedingUpdateScope checkNeedsUpdateScope(object, context);
 #endif
 
   if (object.isBoxModelObject() || object.isSVG()) {
     updateTransform(object, context);
@@ skipping 21 matching lines @@
   updateOverflowClip(object, context);
   updatePerspective(object, context);
   updateSvgLocalToBorderBoxTransform(object, context);
   updateScrollAndScrollTranslation(object, context);
   updateOutOfFlowContext(object, context);
 
   context.forceSubtreeUpdate |= object.subtreeNeedsPaintPropertyUpdate();
 }
 
 }  // namespace blink