Revamp asynchronous (load) event dispatching for SVG elements

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 "config.h"
 
 #include "core/svg/SVGUseElement.h"
 
 #include "bindings/core/v8/ExceptionStatePlaceholder.h"
+#include "core/SVGNames.h"
 #include "core/XLinkNames.h"
 #include "core/dom/Document.h"
 #include "core/dom/ElementTraversal.h"
 #include "core/events/Event.h"
 #include "core/dom/shadow/ElementShadow.h"
 #include "core/dom/shadow/ShadowRoot.h"
 #include "core/fetch/FetchRequest.h"
 #include "core/fetch/ResourceFetcher.h"
 #include "core/layout/svg/LayoutSVGTransformableContainer.h"
 #include "core/svg/SVGGElement.h"
 #include "core/svg/SVGLengthContext.h"
 #include "core/svg/SVGSVGElement.h"
 #include "core/xml/parser/XMLDocumentParser.h"
 
 namespace blink {
 
+static SVGUseEventSender& svgUseLoadEventSender()
+{
+    DEFINE_STATIC_LOCAL(SVGUseEventSender, sharedLoadEventSender, (EventTypeNames::load));
+    return sharedLoadEventSender;
+}
+
 inline SVGUseElement::SVGUseElement(Document& document)
     : SVGGraphicsElement(SVGNames::useTag, document)
     , SVGURIReference(this)
     , m_x(SVGAnimatedLength::create(this, SVGNames::xAttr, SVGLength::create(SVGLengthMode::Width), AllowNegativeLengths))
     , m_y(SVGAnimatedLength::create(this, SVGNames::yAttr, SVGLength::create(SVGLengthMode::Height), AllowNegativeLengths))
     , m_width(SVGAnimatedLength::create(this, SVGNames::widthAttr, SVGLength::create(SVGLengthMode::Width), ForbidNegativeLengths))
     , m_height(SVGAnimatedLength::create(this, SVGNames::heightAttr, SVGLength::create(SVGLengthMode::Height), ForbidNegativeLengths))
     , m_haveFiredLoadEvent(false)
     , m_needsShadowTreeRecreation(false)
-    , m_svgLoadEventTimer(this, &SVGElement::svgLoadEventTimerFired)
 {
     ASSERT(hasCustomStyleCallbacks());
 
     addToPropertyMap(m_x);
     addToPropertyMap(m_y);
     addToPropertyMap(m_width);
     addToPropertyMap(m_height);
 }
 
 PassRefPtrWillBeRawPtr<SVGUseElement> SVGUseElement::create(Document& document)
 {
     // Always build a user agent #shadow-root for SVGUseElement.
     RefPtrWillBeRawPtr<SVGUseElement> use = adoptRefWillBeNoop(new SVGUseElement(document));
     use->ensureUserAgentShadowRoot();
     return use.release();
 }
 
 SVGUseElement::~SVGUseElement()
 {
     setDocumentResource(0);
 #if !ENABLE(OILPAN)
     clearResourceReferences();
 #endif
+    svgUseLoadEventSender().cancelEvent(this);
 }
 
 DEFINE_TRACE(SVGUseElement)
 {
     visitor->trace(m_x);
     visitor->trace(m_y);
     visitor->trace(m_width);
     visitor->trace(m_height);
     visitor->trace(m_targetElementInstance);
     SVGGraphicsElement::trace(visitor);
@@ skipping 11 matching lines @@
 
 Node::InsertionNotificationRequest SVGUseElement::insertedInto(ContainerNode* rootParent)
 {
     // This functions exists to assure assumptions made in the code regarding SVGElementInstance creation/destruction are satisfied.
     SVGGraphicsElement::insertedInto(rootParent);
     if (!rootParent->inDocument())
         return InsertionDone;
     ASSERT(!m_targetElementInstance || !isWellFormedDocument(&document()));
     ASSERT(!hasPendingResources() || !isWellFormedDocument(&document()));
     invalidateShadowTree();
-    if (!isStructurallyExternal())
-        sendSVGLoadEventIfPossibleAsynchronously();
     return InsertionDone;
 }
 
 void SVGUseElement::removedFrom(ContainerNode* rootParent)
 {
     SVGGraphicsElement::removedFrom(rootParent);
     if (rootParent->inDocument())
         clearResourceReferences();
 }
 
@@ skipping 587 matching lines @@
         || m_width->currentValue()->isRelative()
         || m_height->currentValue()->isRelative())
         return true;
 
     if (!m_targetElementInstance)
         return false;
 
     return m_targetElementInstance->hasRelativeLengths();
 }
 
+void SVGUseElement::dispatchPendingEvent(SVGUseEventSender* eventSender)
+{
+    ASSERT_UNUSED(eventSender, eventSender == &svgUseLoadEventSender());
+    ASSERT(isStructurallyExternal() && m_haveFiredLoadEvent);
+    dispatchEvent(Event::create(EventTypeNames::load));
+}
+
 void SVGUseElement::notifyFinished(Resource* resource)
 {
     if (!inDocument())
         return;
 
     invalidateShadowTree();
     if (resource->errorOccurred())
         dispatchEvent(Event::create(EventTypeNames::error));

[fs, 2015/05/20 14:43:34]

It might make sense to have the 'error' event be equally async as the 'load'
event.

     else if (!resource->wasCanceled()) {
         if (m_haveFiredLoadEvent)
             return;
         if (!isStructurallyExternal())
             return;
         ASSERT(!m_haveFiredLoadEvent);
         m_haveFiredLoadEvent = true;
-        sendSVGLoadEventIfPossibleAsynchronously();
+        svgUseLoadEventSender().dispatchEventSoon(this);
     }
 }
 
 bool SVGUseElement::resourceIsStillLoading()
 {
     if (m_resource && m_resource->isLoading())
         return true;
     return false;
 }
 
@@ skipping 17 matching lines @@
 
     if (m_resource)
         m_resource->removeClient(this);
 
     m_resource = resource;
     if (m_resource)
         m_resource->addClient(this);
 }
 
 }