Add a new mechanism for watching SVGElement 'href' targets

third_party/WebKit/Source/core/svg/SVGTextPathElement.cpp

 /*
  * Copyright (C) 2007 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2010 Rob Buis <rwlbuis@gmail.com>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  */
 
 #include "core/svg/SVGTextPathElement.h"
 
+#include "core/dom/IdTargetObserver.h"
 #include "core/layout/svg/LayoutSVGTextPath.h"
-#include "core/svg/SVGTreeScopeResources.h"
 
 namespace blink {
 
 template <>
 const SVGEnumerationStringEntries&
 getStaticStringEntries<SVGTextPathMethodType>() {
   DEFINE_STATIC_LOCAL(SVGEnumerationStringEntries, entries, ());
   if (entries.isEmpty()) {
     entries.push_back(std::make_pair(SVGTextPathMethodAlign, "align"));
     entries.push_back(std::make_pair(SVGTextPathMethodStretch, "stretch"));
@@ skipping 33 matching lines @@
 }
 
 DEFINE_NODE_FACTORY(SVGTextPathElement)
 
 SVGTextPathElement::~SVGTextPathElement() {}
 
 DEFINE_TRACE(SVGTextPathElement) {
   visitor->trace(m_startOffset);
   visitor->trace(m_method);
   visitor->trace(m_spacing);
+  visitor->trace(m_targetIdObserver);
   SVGTextContentElement::trace(visitor);
   SVGURIReference::trace(visitor);
 }
 
 void SVGTextPathElement::clearResourceReferences() {
+  unobserveTarget(m_targetIdObserver);
   removeAllOutgoingReferences();
 }
 
 void SVGTextPathElement::svgAttributeChanged(const QualifiedName& attrName) {
   if (SVGURIReference::isKnownAttribute(attrName)) {
     SVGElement::InvalidationGuard invalidationGuard(this);
     buildPendingResource();
     return;
   }
 
@@ skipping 21 matching lines @@
       (isSVGAElement(*parentNode()) || isSVGTextElement(*parentNode())))
     return SVGElement::layoutObjectIsNeeded(style);
 
   return false;
 }
 
 void SVGTextPathElement::buildPendingResource() {
   clearResourceReferences();
   if (!isConnected())
     return;
-
-  AtomicString id;
-  Element* target = SVGURIReference::targetElementFromIRIString(
-      hrefString(), treeScope(), &id);
-  if (!target) {
-    // Do not register as pending if we are already pending this resource.
-    if (treeScope().ensureSVGTreeScopedResources().isElementPendingResource(
-            *this, id))
-      return;
-    if (!id.isEmpty()) {
-      treeScope().ensureSVGTreeScopedResources().addPendingResource(id, *this);
-      DCHECK(hasPendingResources());
-    }
-  } else if (isSVGPathElement(*target)) {
+  Element* target = observeTarget(m_targetIdObserver, *this);
+  if (isSVGPathElement(target)) {
     // Register us with the target in the dependencies map. Any change of
     // hrefElement that leads to relayout/repainting now informs us, so we can
     // react to it.
-    addReferenceTo(toSVGElement((target)));
+    addReferenceTo(toSVGElement(target));
   }
 
   if (LayoutObject* layoutObject = this->layoutObject())
     markForLayoutAndParentResourceInvalidation(layoutObject);
 }
 
 Node::InsertionNotificationRequest SVGTextPathElement::insertedInto(
     ContainerNode* rootParent) {
   SVGTextContentElement::insertedInto(rootParent);
   buildPendingResource();
   return InsertionDone;
 }
 
 void SVGTextPathElement::removedFrom(ContainerNode* rootParent) {
   SVGTextContentElement::removedFrom(rootParent);
   if (rootParent->isConnected())
     clearResourceReferences();
 }
 
 bool SVGTextPathElement::selfHasRelativeLengths() const {
   return m_startOffset->currentValue()->isRelative() ||
          SVGTextContentElement::selfHasRelativeLengths();
 }
 
 }  // namespace blink