Use IdTargetObserver in SVGUseElement

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

 /*
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Nikolas Zimmermann
  * <zimmermann@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007 Rob Buis <buis@kde.org>
  * Copyright (C) Research In Motion Limited 2009-2010. All rights reserved.
  * Copyright (C) 2011 Torch Mobile (Beijing) Co. Ltd. All rights reserved.
  * Copyright (C) 2012 University of Szeged
  * Copyright (C) 2012 Renata Hodovan <reni@webkit.org>
  *
  * 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/SVGUseElement.h"
 
-#include "bindings/core/v8/ExceptionState.h"
 #include "core/SVGNames.h"
 #include "core/XLinkNames.h"
 #include "core/dom/Document.h"
 #include "core/dom/ElementTraversal.h"
+#include "core/dom/IdTargetObserver.h"
 #include "core/dom/StyleChangeReason.h"
 #include "core/dom/TaskRunnerHelper.h"
-#include "core/dom/shadow/ElementShadow.h"
 #include "core/dom/shadow/ShadowRoot.h"
 #include "core/events/Event.h"
 #include "core/layout/svg/LayoutSVGTransformableContainer.h"
 #include "core/svg/SVGGElement.h"
 #include "core/svg/SVGLengthContext.h"
 #include "core/svg/SVGSVGElement.h"
 #include "core/svg/SVGSymbolElement.h"
 #include "core/svg/SVGTitleElement.h"
-#include "core/svg/SVGTreeScopeResources.h"
 #include "core/xml/parser/XMLDocumentParser.h"
 #include "platform/loader/fetch/FetchRequest.h"
 #include "platform/loader/fetch/ResourceFetcher.h"
 #include "wtf/Vector.h"
 
 namespace blink {
 
 inline SVGUseElement::SVGUseElement(Document& document)
     : SVGGraphicsElement(SVGNames::useTag, document),
       SVGURIReference(this),
@@ skipping 36 matching lines @@
 void SVGUseElement::dispose() {
   setDocumentResource(nullptr);
 }
 
 DEFINE_TRACE(SVGUseElement) {
   visitor->trace(m_x);
   visitor->trace(m_y);
   visitor->trace(m_width);
   visitor->trace(m_height);
   visitor->trace(m_targetElementInstance);
+  visitor->trace(m_targetIdObserver);
   visitor->trace(m_resource);
   SVGGraphicsElement::trace(visitor);
   SVGURIReference::trace(visitor);
   DocumentResourceClient::trace(visitor);
 }
 
 #if DCHECK_IS_ON()
 static inline bool isWellFormedDocument(Document* document) {
   if (document->isXMLDocument())
     return static_cast<XMLDocumentParser*>(document->parser())->wellFormed();
@@ skipping 10 matching lines @@
     return InsertionDone;
   ASSERT(!m_targetElementInstance || !isWellFormedDocument(&document()));
   ASSERT(!hasPendingResources() || !isWellFormedDocument(&document()));
   invalidateShadowTree();
   return InsertionDone;
 }
 
 void SVGUseElement::removedFrom(ContainerNode* rootParent) {
   SVGGraphicsElement::removedFrom(rootParent);
   if (rootParent->isConnected()) {
-    clearInstanceRoot();
-    removeAllOutgoingReferences();
+    clearResourceReference();
     cancelShadowTreeRecreation();
   }
 }
 
 static void transferUseWidthAndHeightIfNeeded(
     const SVGUseElement& use,
     SVGElement& shadowElement,
     const SVGElement& originalElement) {
   DEFINE_STATIC_LOCAL(const AtomicString, hundredPercentString, ("100%"));
   // Use |originalElement| for checking the element type, because we will
@@ skipping 137 matching lines @@
   m_needsShadowTreeRecreation = true;
   document().scheduleUseShadowTreeUpdate(*this);
 }
 
 void SVGUseElement::cancelShadowTreeRecreation() {
   m_needsShadowTreeRecreation = false;
   document().unscheduleUseShadowTreeUpdate(*this);
 }
 
 void SVGUseElement::clearInstanceRoot() {
-  if (m_targetElementInstance)
-    m_targetElementInstance = nullptr;
+  m_targetElementInstance = nullptr;
 }
 
-void SVGUseElement::clearShadowTree() {
+void SVGUseElement::clearResourceReference() {
+  unobserveTarget(m_targetIdObserver);
   clearInstanceRoot();
-
-  // FIXME: We should try to optimize this, to at least allow partial reclones.
-  if (ShadowRoot* shadowTreeRootElement = userAgentShadowRoot())
-    shadowTreeRootElement->removeChildren(OmitSubtreeModifiedEvent);
-
   removeAllOutgoingReferences();
 }
 
 Element* SVGUseElement::resolveTargetElement() {
   if (m_elementIdentifier.isEmpty())
     return nullptr;
-  const TreeScope* lookupScope = nullptr;
-  if (m_elementIdentifierIsLocal)
-    lookupScope = &treeScope();
-  else if (resourceIsValid())
-    lookupScope = m_resource->document();
-  else
+  if (m_elementIdentifierIsLocal) {
+    return observeTarget(m_targetIdObserver, treeScope(), m_elementIdentifier,
+                         WTF::bind(&SVGUseElement::invalidateShadowTree,
+                                   wrapWeakPersistent(this)));
+  }
+  if (!resourceIsValid())
     return nullptr;
-  Element* target = lookupScope->getElementById(m_elementIdentifier);
-  // TODO(fs): Why would the Element not be "connected" at this point?
-  if (target && target->isConnected())
-    return target;
-  // Don't record any pending references for external resources.
-  if (!m_resource) {
-    treeScope().ensureSVGTreeScopedResources().addPendingResource(
-        m_elementIdentifier, *this);
-    DCHECK(hasPendingResources());
-  }
-  return nullptr;
+  return m_resource->document()->getElementById(m_elementIdentifier);
 }
 
 void SVGUseElement::buildPendingResource() {
   if (inUseShadowTree())
     return;
-  clearShadowTree();
+  // FIXME: We should try to optimize this, to at least allow partial reclones.
+  userAgentShadowRoot()->removeChildren(OmitSubtreeModifiedEvent);
+  clearResourceReference();
   cancelShadowTreeRecreation();
   if (!isConnected())
     return;
   Element* target = resolveTargetElement();
-  if (target && target->isSVGElement()) {
+  // TODO(fs): Why would the Element not be "connected" at this point?
+  if (target && target->isConnected() && target->isSVGElement()) {
     buildShadowAndInstanceTree(toSVGElement(*target));
     invalidateDependentShadowTrees();
   }
 
   ASSERT(!m_needsShadowTreeRecreation);
 }
 
 String SVGUseElement::title() const {
   // Find the first <title> child in <use> which doesn't cover shadow tree.
   if (Element* titleElement = Traversal<SVGTitleElement>::firstChild(*this))
@@ skipping 110 matching lines @@
     return;
 
   // Assure shadow tree building was successful.
   ASSERT(m_targetElementInstance);
   ASSERT(m_targetElementInstance->correspondingUseElement() == this);
   ASSERT(m_targetElementInstance->correspondingElement() == &target);
 
   // Expand all <use> elements in the shadow tree.
   // Expand means: replace the actual <use> element by what it references.
   if (!expandUseElementsInShadowTree()) {
-    clearShadowTree();
+    shadowTreeRootElement->removeChildren(OmitSubtreeModifiedEvent);
+    clearResourceReference();
     return;
   }
 
   // If the instance root was a <use>, it could have been replaced now, so
   // reset |m_targetElementInstance|.
   m_targetElementInstance =
       toSVGElementOrDie(shadowTreeRootElement->firstChild());
   ASSERT(m_targetElementInstance->parentNode() == shadowTreeRootElement);
 
   // Update relative length information.
@@ skipping 264 matching lines @@
 
   if (m_resource)
     m_resource->removeClient(this);
 
   m_resource = resource;
   if (m_resource)
     m_resource->addClient(this);
 }
 
 }  // namespace blink