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

   1 /*
   2  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Nikolas Zimmermann <zimmermann@kde.org>
   3  * Copyright (C) 2004, 2005, 2006, 2007 Rob Buis <buis@kde.org>
   4  * Copyright (C) Research In Motion Limited 2009-2010. All rights reserved.
   5  * Copyright (C) 2011 Torch Mobile (Beijing) Co. Ltd. All rights reserved.
   6  * Copyright (C) 2012 University of Szeged
   7  * Copyright (C) 2012 Renata Hodovan <reni@webkit.org>
   8  *
   9  * This library is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Library General Public
  11  * License as published by the Free Software Foundation; either
  12  * version 2 of the License, or (at your option) any later version.
  13  *
  14  * This library is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * Library General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Library General Public License
  20  * along with this library; see the file COPYING.LIB.  If not, write to
  21  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  22  * Boston, MA 02110-1301, USA.
  23  */
  24
  25 #include "config.h"
  26
  27 #include "core/svg/SVGUseElement.h"
  28
  29 #include "bindings/core/v8/ExceptionStatePlaceholder.h"
  30 #include "core/SVGNames.h"
  31 #include "core/XLinkNames.h"
  32 #include "core/dom/Document.h"
  33 #include "core/dom/ElementTraversal.h"
  34 #include "core/events/Event.h"
  35 #include "core/dom/shadow/ElementShadow.h"
  36 #include "core/dom/shadow/ShadowRoot.h"
  37 #include "core/fetch/FetchRequest.h"
  38 #include "core/fetch/ResourceFetcher.h"
  39 #include "core/layout/svg/LayoutSVGTransformableContainer.h"
  40 #include "core/svg/SVGGElement.h"
  41 #include "core/svg/SVGLengthContext.h"
  42 #include "core/svg/SVGSVGElement.h"
  43 #include "core/xml/parser/XMLDocumentParser.h"
  44
  45 namespace blink {
  46
  47 static SVGUseEventSender& svgUseLoadEventSender()
  48 {
  49     DEFINE_STATIC_LOCAL(SVGUseEventSender, sharedLoadEventSender, (EventTypeNames::load));
  50     return sharedLoadEventSender;
  51 }
  52
  53 inline SVGUseElement::SVGUseElement(Document& document)
  54     : SVGGraphicsElement(SVGNames::useTag, document)
  55     , SVGURIReference(this)
  56     , m_x(SVGAnimatedLength::create(this, SVGNames::xAttr, SVGLength::create(SVGLengthMode::Width), AllowNegativeLengths))
  57     , m_y(SVGAnimatedLength::create(this, SVGNames::yAttr, SVGLength::create(SVGLengthMode::Height), AllowNegativeLengths))
  58     , m_width(SVGAnimatedLength::create(this, SVGNames::widthAttr, SVGLength::create(SVGLengthMode::Width), ForbidNegativeLengths))
  59     , m_height(SVGAnimatedLength::create(this, SVGNames::heightAttr, SVGLength::create(SVGLengthMode::Height), ForbidNegativeLengths))
  60     , m_haveFiredLoadEvent(false)
  61     , m_needsShadowTreeRecreation(false)
  62 {
  63     ASSERT(hasCustomStyleCallbacks());
  64
  65     addToPropertyMap(m_x);
  66     addToPropertyMap(m_y);
  67     addToPropertyMap(m_width);
  68     addToPropertyMap(m_height);
  69 }
  70
  71 PassRefPtrWillBeRawPtr<SVGUseElement> SVGUseElement::create(Document& document)
  72 {
  73     // Always build a user agent #shadow-root for SVGUseElement.
  74     RefPtrWillBeRawPtr<SVGUseElement> use = adoptRefWillBeNoop(new SVGUseElement(document));
  75     use->ensureUserAgentShadowRoot();
  76     return use.release();
  77 }
  78
  79 SVGUseElement::~SVGUseElement()
  80 {
  81     setDocumentResource(0);
  82 #if !ENABLE(OILPAN)
  83     clearShadowTree();
  84     cancelShadowTreeRecreation();
  85 #endif
  86     svgUseLoadEventSender().cancelEvent(this);
  87 }
  88
  89 DEFINE_TRACE(SVGUseElement)
  90 {
  91     visitor->trace(m_x);
  92     visitor->trace(m_y);
  93     visitor->trace(m_width);
  94     visitor->trace(m_height);
  95     visitor->trace(m_targetElementInstance);
  96     SVGGraphicsElement::trace(visitor);
  97     SVGURIReference::trace(visitor);
  98 }
  99
 100 #if ENABLE(ASSERT)
 101 static inline bool isWellFormedDocument(Document* document)
 102 {
 103     if (document->isXMLDocument())
 104         return static_cast<XMLDocumentParser*>(document->parser())->wellFormed();
 105     return true;
 106 }
 107 #endif
 108
 109 Node::InsertionNotificationRequest SVGUseElement::insertedInto(ContainerNode* rootParent)
 110 {
 111     // This functions exists to assure assumptions made in the code regarding SVGElementInstance creation/destruction are satisfied.
 112     SVGGraphicsElement::insertedInto(rootParent);
 113     if (!rootParent->inDocument())
 114         return InsertionDone;
 115     ASSERT(!m_targetElementInstance || !isWellFormedDocument(&document()));
 116     ASSERT(!hasPendingResources() || !isWellFormedDocument(&document()));
 117     invalidateShadowTree();
 118     return InsertionDone;
 119 }
 120
 121 void SVGUseElement::removedFrom(ContainerNode* rootParent)
 122 {
 123     SVGGraphicsElement::removedFrom(rootParent);
 124     if (rootParent->inDocument()) {
 125         clearShadowTree();
 126         cancelShadowTreeRecreation();
 127     }
 128 }
 129
 130 TreeScope* SVGUseElement::referencedScope() const
 131 {
 132     if (isStructurallyExternal())
 133         return externalDocument();
 134     return &treeScope();
 135 }
 136
 137 Document* SVGUseElement::externalDocument() const
 138 {
 139     if (m_resource && m_resource->isLoaded()) {
 140         // Gracefully handle error condition.
 141         if (m_resource->errorOccurred())
 142             return nullptr;
 143         ASSERT(m_resource->document());
 144         return m_resource->document();
 145     }
 146     return nullptr;
 147 }
 148
 149 void transferUseWidthAndHeightIfNeeded(const SVGUseElement& use, SVGElement* shadowElement, const SVGElement& originalElement)
 150 {
 151     DEFINE_STATIC_LOCAL(const AtomicString, hundredPercentString, ("100%", AtomicString::ConstructFromLiteral));
 152     ASSERT(shadowElement);
 153     if (isSVGSymbolElement(*shadowElement)) {
 154         // Spec (<use> on <symbol>): This generated 'svg' will always have explicit values for attributes width and height.
 155         // If attributes width and/or height are provided on the 'use' element, then these attributes
 156         // will be transferred to the generated 'svg'. If attributes width and/or height are not specified,
 157         // the generated 'svg' element will use values of 100% for these attributes.
 158         shadowElement->setAttribute(SVGNames::widthAttr, use.width()->isSpecified() ? AtomicString(use.width()->currentValue()->valueAsString()) : hundredPercentString);
 159         shadowElement->setAttribute(SVGNames::heightAttr, use.height()->isSpecified() ? AtomicString(use.height()->currentValue()->valueAsString()) : hundredPercentString);
 160     } else if (isSVGSVGElement(*shadowElement)) {
 161         // Spec (<use> on <svg>): If attributes width and/or height are provided on the 'use' element, then these
 162         // values will override the corresponding attributes on the 'svg' in the generated tree.
 163         if (use.width()->isSpecified())
 164             shadowElement->setAttribute(SVGNames::widthAttr, AtomicString(use.width()->currentValue()->valueAsString()));
 165         else
 166             shadowElement->setAttribute(SVGNames::widthAttr, originalElement.getAttribute(SVGNames::widthAttr));
 167         if (use.height()->isSpecified())
 168             shadowElement->setAttribute(SVGNames::heightAttr, AtomicString(use.height()->currentValue()->valueAsString()));
 169         else
 170             shadowElement->setAttribute(SVGNames::heightAttr, originalElement.getAttribute(SVGNames::heightAttr));
 171     }
 172 }
 173
 174 bool SVGUseElement::isPresentationAttribute(const QualifiedName& attrName) const
 175 {
 176     if (attrName == SVGNames::xAttr || attrName == SVGNames::yAttr)
 177         return true;
 178     return SVGGraphicsElement::isPresentationAttribute(attrName);
 179 }
 180
 181 bool SVGUseElement::isPresentationAttributeWithSVGDOM(const QualifiedName& attrName) const
 182 {
 183     if (attrName == SVGNames::xAttr || attrName == SVGNames::yAttr)
 184         return true;
 185     return SVGGraphicsElement::isPresentationAttributeWithSVGDOM(attrName);
 186 }
 187
 188 void SVGUseElement::collectStyleForPresentationAttribute(const QualifiedName& name, const AtomicString& value, MutableStylePropertySet* style)
 189 {
 190     RefPtrWillBeRawPtr<SVGAnimatedPropertyBase> property = propertyFromAttribute(name);
 191     if (property == m_x)
 192         addSVGLengthPropertyToPresentationAttributeStyle(style, CSSPropertyX, *m_x->currentValue());
 193     else if (property == m_y)
 194         addSVGLengthPropertyToPresentationAttributeStyle(style, CSSPropertyY, *m_y->currentValue());
 195     else
 196         SVGGraphicsElement::collectStyleForPresentationAttribute(name, value, style);
 197 }
 198
 199 void SVGUseElement::svgAttributeChanged(const QualifiedName& attrName)
 200 {
 201     if (attrName == SVGNames::xAttr
 202         || attrName == SVGNames::yAttr
 203         || attrName == SVGNames::widthAttr
 204         || attrName == SVGNames::heightAttr) {
 205         SVGElement::InvalidationGuard invalidationGuard(this);
 206
 207         if (attrName == SVGNames::xAttr
 208             || attrName == SVGNames::yAttr) {
 209             invalidateSVGPresentationAttributeStyle();
 210             setNeedsStyleRecalc(LocalStyleChange,
 211                 StyleChangeReasonForTracing::fromAttribute(attrName));
 212         }
 213
 214         updateRelativeLengthsInformation();
 215         if (m_targetElementInstance) {
 216             ASSERT(m_targetElementInstance->correspondingElement());
 217             transferUseWidthAndHeightIfNeeded(*this, m_targetElementInstance.get(), *m_targetElementInstance->correspondingElement());
 218         }
 219
 220         LayoutObject* object = this->layoutObject();
 221         if (object)
 222             markForLayoutAndParentResourceInvalidation(object);
 223         return;
 224     }
 225
 226     if (SVGURIReference::isKnownAttribute(attrName)) {
 227         SVGElement::InvalidationGuard invalidationGuard(this);
 228         if (isStructurallyExternal()) {
 229             KURL url = document().completeURL(hrefString());
 230             if (url.hasFragmentIdentifier()) {
 231                 FetchRequest request(ResourceRequest(url), localName());
 232                 setDocumentResource(DocumentResource::fetchSVGDocument(request, document().fetcher()));
 233             }
 234         } else {
 235             setDocumentResource(0);
 236         }
 237
 238         invalidateShadowTree();
 239
 240         return;
 241     }
 242
 243     SVGGraphicsElement::svgAttributeChanged(attrName);
 244 }
 245
 246 static bool isDisallowedElement(Node* node)
 247 {
 248     // Spec: "Any 'svg', 'symbol', 'g', graphics element or other 'use' is potentially a template object that can be re-used
 249     // (i.e., "instanced") in the SVG document via a 'use' element."
 250     // "Graphics Element" is defined as 'circle', 'ellipse', 'image', 'line', 'path', 'polygon', 'polyline', 'rect', 'text'
 251     // Excluded are anything that is used by reference or that only make sense to appear once in a document.
 252     // We must also allow the shadow roots of other use elements.
 253     if (node->isShadowRoot() || node->isTextNode())
 254         return false;
 255
 256     if (!node->isSVGElement())
 257         return true;
 258
 259     Element* element = toElement(node);
 260
 261     DEFINE_STATIC_LOCAL(HashSet<QualifiedName>, allowedElementTags, ());
 262     if (allowedElementTags.isEmpty()) {
 263         allowedElementTags.add(SVGNames::aTag);
 264         allowedElementTags.add(SVGNames::circleTag);
 265         allowedElementTags.add(SVGNames::descTag);
 266         allowedElementTags.add(SVGNames::ellipseTag);
 267         allowedElementTags.add(SVGNames::gTag);
 268         allowedElementTags.add(SVGNames::imageTag);
 269         allowedElementTags.add(SVGNames::lineTag);
 270         allowedElementTags.add(SVGNames::metadataTag);
 271         allowedElementTags.add(SVGNames::pathTag);
 272         allowedElementTags.add(SVGNames::polygonTag);
 273         allowedElementTags.add(SVGNames::polylineTag);
 274         allowedElementTags.add(SVGNames::rectTag);
 275         allowedElementTags.add(SVGNames::svgTag);
 276         allowedElementTags.add(SVGNames::switchTag);
 277         allowedElementTags.add(SVGNames::symbolTag);
 278         allowedElementTags.add(SVGNames::textTag);
 279         allowedElementTags.add(SVGNames::textPathTag);
 280         allowedElementTags.add(SVGNames::titleTag);
 281         allowedElementTags.add(SVGNames::tspanTag);
 282         allowedElementTags.add(SVGNames::useTag);
 283     }
 284     return !allowedElementTags.contains<SVGAttributeHashTranslator>(element->tagQName());
 285 }
 286
 287 static bool subtreeContainsDisallowedElement(Node* start)
 288 {
 289     if (isDisallowedElement(start))
 290         return true;
 291
 292     for (Node* cur = start->firstChild(); cur; cur = cur->nextSibling()) {
 293         if (subtreeContainsDisallowedElement(cur))
 294             return true;
 295     }
 296
 297     return false;
 298 }
 299
 300 void SVGUseElement::scheduleShadowTreeRecreation()
 301 {
 302     if (inUseShadowTree())
 303         return;
 304     m_needsShadowTreeRecreation = true;
 305     document().scheduleUseShadowTreeUpdate(*this);
 306 }
 307
 308 void SVGUseElement::cancelShadowTreeRecreation()
 309 {
 310     m_needsShadowTreeRecreation = false;
 311     document().unscheduleUseShadowTreeUpdate(*this);
 312 }
 313
 314 void SVGUseElement::clearInstanceRoot()
 315 {
 316     if (m_targetElementInstance)
 317         m_targetElementInstance = nullptr;
 318 }
 319
 320 void SVGUseElement::clearShadowTree()
 321 {
 322     clearInstanceRoot();
 323
 324     // FIXME: We should try to optimize this, to at least allow partial reclones.
 325     if (ShadowRoot* shadowTreeRootElement = userAgentShadowRoot())
 326         shadowTreeRootElement->removeChildren(OmitSubtreeModifiedEvent);
 327
 328     removeAllOutgoingReferences();
 329 }
 330
 331 void SVGUseElement::buildPendingResource()
 332 {
 333     if (inUseShadowTree())
 334         return;
 335     clearShadowTree();
 336     cancelShadowTreeRecreation();
 337     if (!referencedScope() || !inDocument())
 338         return;
 339
 340     AtomicString id;
 341     Element* target = SVGURIReference::targetElementFromIRIString(hrefString(), treeScope(), &id, externalDocument());
 342     if (!target || !target->inDocument()) {
 343         // If we can't find the target of an external element, just give up.
 344         // We can't observe if the target somewhen enters the external document, nor should we do it.
 345         if (externalDocument())
 346             return;
 347         if (id.isEmpty())
 348             return;
 349
 350         referencedScope()->document().accessSVGExtensions().addPendingResource(id, this);
 351         ASSERT(hasPendingResources());
 352         return;
 353     }
 354
 355     if (target->isSVGElement()) {
 356         buildShadowAndInstanceTree(toSVGElement(target));
 357         invalidateDependentShadowTrees();
 358     }
 359
 360     ASSERT(!m_needsShadowTreeRecreation);
 361 }
 362
 363 static PassRefPtrWillBeRawPtr<Node> cloneNodeAndAssociate(Node& toClone)
 364 {
 365     RefPtrWillBeRawPtr<Node> clone = toClone.cloneNode(false);
 366     if (!clone->isSVGElement())
 367         return clone.release();
 368
 369     SVGElement& svgElement = toSVGElement(toClone);
 370     ASSERT(!svgElement.correspondingElement());
 371     toSVGElement(clone.get())->setCorrespondingElement(&svgElement);
 372     if (EventTargetData* data = toClone.eventTargetData())
 373         data->eventListenerMap.copyEventListenersNotCreatedFromMarkupToTarget(clone.get());
 374     TrackExceptionState exceptionState;
 375     for (Node* node = toClone.firstChild(); node && !exceptionState.hadException(); node = node->nextSibling())
 376         clone->appendChild(cloneNodeAndAssociate(*node), exceptionState);
 377     return clone.release();
 378 }
 379
 380 void SVGUseElement::buildShadowAndInstanceTree(SVGElement* target)
 381 {
 382     ASSERT(!m_targetElementInstance);
 383     ASSERT(!m_needsShadowTreeRecreation);
 384
 385     // <use> creates a "user agent" shadow root. Do not build the shadow/instance tree for <use>
 386     // elements living in a user agent shadow tree because they will get expanded in a second
 387     // pass -- see expandUseElementsInShadowTree().
 388     if (inUseShadowTree())
 389         return;
 390
 391     // Do not allow self-referencing.
 392     // 'target' may be null, if it's a non SVG namespaced element.
 393     if (!target || target == this || isDisallowedElement(target))
 394         return;
 395
 396     // Set up root SVG element in shadow tree.
 397     RefPtrWillBeRawPtr<Element> newChild = target->cloneElementWithoutChildren();
 398     m_targetElementInstance = toSVGElement(newChild.get());
 399     ShadowRoot* shadowTreeRootElement = userAgentShadowRoot();
 400     shadowTreeRootElement->appendChild(newChild.release());
 401
 402     // Clone the target subtree into the shadow tree, not handling <use> and <symbol> yet.
 403
 404     // SVG specification does not say a word about <use> & cycles. My view on this is: just ignore it!
 405     // Non-appearing <use> content is easier to debug, then half-appearing content.
 406     if (!buildShadowTree(target, m_targetElementInstance.get(), false)) {
 407         clearShadowTree();
 408         return;
 409     }
 410
 411     if (instanceTreeIsLoading(m_targetElementInstance.get()))
 412         return;
 413
 414     // Assure shadow tree building was successfull
 415     ASSERT(m_targetElementInstance);
 416     ASSERT(m_targetElementInstance->correspondingUseElement() == this);
 417     ASSERT(m_targetElementInstance->correspondingElement() == target);
 418
 419     // Expand all <use> elements in the shadow tree.
 420     // Expand means: replace the actual <use> element by what it references.
 421     if (!expandUseElementsInShadowTree(m_targetElementInstance.get())) {
 422         clearShadowTree();
 423         return;
 424     }
 425
 426     // Expand all <symbol> elements in the shadow tree.
 427     // Expand means: replace the actual <symbol> element by the <svg> element.
 428     expandSymbolElementsInShadowTree(toSVGElement(shadowTreeRootElement->firstChild()));
 429
 430     m_targetElementInstance = toSVGElement(shadowTreeRootElement->firstChild());
 431     transferUseWidthAndHeightIfNeeded(*this, m_targetElementInstance.get(), *m_targetElementInstance->correspondingElement());
 432
 433     ASSERT(m_targetElementInstance->parentNode() == shadowTreeRootElement);
 434
 435     // Update relative length information.
 436     updateRelativeLengthsInformation();
 437 }
 438
 439 LayoutObject* SVGUseElement::createLayoutObject(const ComputedStyle&)
 440 {
 441     return new LayoutSVGTransformableContainer(this);
 442 }
 443
 444 static bool isDirectReference(const SVGElement& element)
 445 {
 446     return isSVGPathElement(element)
 447         || isSVGRectElement(element)
 448         || isSVGCircleElement(element)
 449         || isSVGEllipseElement(element)
 450         || isSVGPolygonElement(element)
 451         || isSVGPolylineElement(element)
 452         || isSVGTextElement(element);
 453 }
 454
 455 void SVGUseElement::toClipPath(Path& path) const
 456 {
 457     ASSERT(path.isEmpty());
 458
 459     const SVGGraphicsElement* element = targetGraphicsElementForClipping();
 460
 461     if (!element)
 462         return;
 463
 464     if (element->isSVGGeometryElement()) {
 465         toSVGGeometryElement(*element).toClipPath(path);
 466         // FIXME: Avoid manual resolution of x/y here. Its potentially harmful.
 467         SVGLengthContext lengthContext(this);
 468         path.translate(FloatSize(m_x->currentValue()->value(lengthContext), m_y->currentValue()->value(lengthContext)));
 469         path.transform(calculateAnimatedLocalTransform());
 470     }
 471 }
 472
 473 SVGGraphicsElement* SVGUseElement::targetGraphicsElementForClipping() const
 474 {
 475     Node* n = userAgentShadowRoot()->firstChild();
 476     if (!n || !n->isSVGElement())
 477         return nullptr;
 478
 479     SVGElement& element = toSVGElement(*n);
 480
 481     if (!element.isSVGGraphicsElement())
 482         return nullptr;
 483
 484     // Spec: "If a <use> element is a child of a clipPath element, it must directly
 485     // reference <path>, <text> or basic shapes elements. Indirect references are an
 486     // error and the clipPath element must be ignored."
 487     // http://dev.w3.org/fxtf/css-masking-1/#the-clip-path
 488     if (!isDirectReference(element)) {
 489         // Spec: Indirect references are an error (14.3.5)
 490         document().accessSVGExtensions().reportError("Not allowed to use indirect reference in <clip-path>");
 491         return nullptr;
 492     }
 493
 494     return &toSVGGraphicsElement(element);
 495 }
 496
 497 bool SVGUseElement::buildShadowTree(SVGElement* target, SVGElement* targetInstance, bool foundUse)
 498 {
 499     ASSERT(target);
 500     ASSERT(targetInstance);
 501
 502     // Spec: If the referenced object is itself a 'use', or if there are 'use' subelements within the referenced
 503     // object, the instance tree will contain recursive expansion of the indirect references to form a complete tree.
 504     if (isSVGUseElement(*target)) {
 505         // We only need to track first degree <use> dependencies. Indirect references are handled
 506         // as the invalidation bubbles up the dependency chain.
 507         if (!foundUse && !isStructurallyExternal()) {
 508             addReferenceTo(target);
 509             foundUse = true;
 510         }
 511     } else if (isDisallowedElement(target)) {
 512         return false;
 513     }
 514
 515     targetInstance->setCorrespondingElement(target);
 516     if (EventTargetData* data = target->eventTargetData())
 517         data->eventListenerMap.copyEventListenersNotCreatedFromMarkupToTarget(targetInstance);
 518
 519     for (Node* child = target->firstChild(); child; child = child->nextSibling()) {
 520         // Skip any disallowed element.
 521         if (isDisallowedElement(child))
 522             continue;
 523
 524         RefPtrWillBeRawPtr<Node> newChild = child->cloneNode(false);
 525         targetInstance->appendChild(newChild.get());
 526         if (newChild->isSVGElement()) {
 527             // Enter recursion, appending new instance tree nodes to the "instance" object.
 528             if (!buildShadowTree(toSVGElement(child), toSVGElement(newChild), foundUse))
 529                 return false;
 530         }
 531     }
 532     return true;
 533 }
 534
 535 bool SVGUseElement::hasCycleUseReferencing(SVGUseElement* use, ContainerNode* targetInstance, SVGElement*& newTarget)
 536 {
 537     ASSERT(referencedScope());
 538     Element* targetElement = SVGURIReference::targetElementFromIRIString(use->hrefString(), *referencedScope());
 539     newTarget = 0;
 540     if (targetElement && targetElement->isSVGElement())
 541         newTarget = toSVGElement(targetElement);
 542
 543     if (!newTarget)
 544         return false;
 545
 546     // Shortcut for self-references
 547     if (newTarget == this)
 548         return true;
 549
 550     AtomicString targetId = newTarget->getIdAttribute();
 551     ContainerNode* instance = targetInstance->parentNode();
 552     while (instance && instance->isSVGElement()) {
 553         SVGElement* element = toSVGElement(instance);
 554         if (element->hasID() && element->getIdAttribute() == targetId && element->document() == newTarget->document())
 555             return true;
 556
 557         instance = instance->parentNode();
 558     }
 559     return false;
 560 }
 561
 562 static inline void removeDisallowedElementsFromSubtree(Element& subtree)
 563 {
 564     ASSERT(!subtree.inDocument());
 565     Element* element = ElementTraversal::firstWithin(subtree);
 566     while (element) {
 567         if (isDisallowedElement(element)) {
 568             Element* next = ElementTraversal::nextSkippingChildren(*element, &subtree);
 569             // The subtree is not in document so this won't generate events that could mutate the tree.
 570             element->parentNode()->removeChild(element);
 571             element = next;
 572         } else {
 573             element = ElementTraversal::next(*element, &subtree);
 574         }
 575     }
 576 }
 577
 578 bool SVGUseElement::expandUseElementsInShadowTree(SVGElement* element)
 579 {
 580     ASSERT(element);
 581     // Why expand the <use> elements in the shadow tree here, and not just
 582     // do this directly in buildShadowTree, if we encounter a <use> element?
 583     //
 584     // Short answer: Because we may miss to expand some elements. For example, if a <symbol>
 585     // contains <use> tags, we'd miss them. So once we're done with setting up the
 586     // actual shadow tree (after the special case modification for svg/symbol) we have
 587     // to walk it completely and expand all <use> elements.
 588     if (isSVGUseElement(*element)) {
 589         SVGUseElement* use = toSVGUseElement(element);
 590         ASSERT(!use->resourceIsStillLoading());
 591
 592         SVGElement* target = 0;
 593         if (hasCycleUseReferencing(toSVGUseElement(use->correspondingElement()), use, target))
 594             return false;
 595
 596         if (target && isDisallowedElement(target))
 597             return false;
 598         // Don't ASSERT(target) here, it may be "pending", too.
 599         // Setup sub-shadow tree root node
 600         RefPtrWillBeRawPtr<SVGGElement> cloneParent = SVGGElement::create(referencedScope()->document());
 601         cloneParent->setCorrespondingElement(use->correspondingElement());
 602
 603         // Move already cloned elements to the new <g> element
 604         for (Node* child = use->firstChild(); child; ) {
 605             Node* nextChild = child->nextSibling();
 606             cloneParent->appendChild(child);
 607             child = nextChild;
 608         }
 609
 610         // Spec: In the generated content, the 'use' will be replaced by 'g', where all attributes from the
 611         // 'use' element except for x, y, width, height and xlink:href are transferred to the generated 'g' element.
 612         transferUseAttributesToReplacedElement(use, cloneParent.get());
 613
 614         if (target) {
 615             RefPtrWillBeRawPtr<Node> newChild = cloneNodeAndAssociate(*target);
 616             ASSERT(newChild->isSVGElement());
 617             transferUseWidthAndHeightIfNeeded(*use, toSVGElement(newChild.get()), *target);
 618             cloneParent->appendChild(newChild.release());
 619         }
 620
 621         // We don't walk the target tree element-by-element, and clone each element,
 622         // but instead use cloneElementWithChildren(). This is an optimization for the common
 623         // case where <use> doesn't contain disallowed elements (ie. <foreignObject>).
 624         // Though if there are disallowed elements in the subtree, we have to remove them.
 625         // For instance: <use> on <g> containing <foreignObject> (indirect case).
 626         if (subtreeContainsDisallowedElement(cloneParent.get()))
 627             removeDisallowedElementsFromSubtree(*cloneParent);
 628
 629         RefPtrWillBeRawPtr<SVGElement> replacingElement(cloneParent.get());
 630
 631         // Replace <use> with referenced content.
 632         ASSERT(use->parentNode());
 633         use->parentNode()->replaceChild(cloneParent.release(), use);
 634
 635         // Expand the siblings because the *element* is replaced and we will
 636         // lose the sibling chain when we are back from recursion.
 637         element = replacingElement.get();
 638         for (RefPtrWillBeRawPtr<SVGElement> sibling = Traversal<SVGElement>::nextSibling(*element); sibling; sibling = Traversal<SVGElement>::nextSibling(*sibling)) {
 639             if (!expandUseElementsInShadowTree(sibling.get()))
 640                 return false;
 641         }
 642     }
 643
 644     for (RefPtrWillBeRawPtr<SVGElement> child = Traversal<SVGElement>::firstChild(*element); child; child = Traversal<SVGElement>::nextSibling(*child)) {
 645         if (!expandUseElementsInShadowTree(child.get()))
 646             return false;
 647     }
 648     return true;
 649 }
 650
 651 void SVGUseElement::expandSymbolElementsInShadowTree(SVGElement* element)
 652 {
 653     ASSERT(element);
 654     if (isSVGSymbolElement(*element)) {
 655         // Spec: The referenced 'symbol' and its contents are deep-cloned into the generated tree,
 656         // with the exception that the 'symbol' is replaced by an 'svg'. This generated 'svg' will
 657         // always have explicit values for attributes width and height. If attributes width and/or
 658         // height are provided on the 'use' element, then these attributes will be transferred to
 659         // the generated 'svg'. If attributes width and/or height are not specified, the generated
 660         // 'svg' element will use values of 100% for these attributes.
 661         ASSERT(referencedScope());
 662         RefPtrWillBeRawPtr<SVGSVGElement> svgElement = SVGSVGElement::create(referencedScope()->document());
 663         // Transfer all data (attributes, etc.) from <symbol> to the new <svg> element.
 664         svgElement->cloneDataFromElement(*element);
 665         svgElement->setCorrespondingElement(element->correspondingElement());
 666
 667         // Move already cloned elements to the new <svg> element
 668         for (Node* child = element->firstChild(); child; ) {
 669             Node* nextChild = child->nextSibling();
 670             svgElement->appendChild(child);
 671             child = nextChild;
 672         }
 673
 674         // We don't walk the target tree element-by-element, and clone each element,
 675         // but instead use cloneNode(deep=true). This is an optimization for the common
 676         // case where <use> doesn't contain disallowed elements (ie. <foreignObject>).
 677         // Though if there are disallowed elements in the subtree, we have to remove them.
 678         // For instance: <use> on <g> containing <foreignObject> (indirect case).
 679         if (subtreeContainsDisallowedElement(svgElement.get()))
 680             removeDisallowedElementsFromSubtree(*svgElement);
 681
 682         RefPtrWillBeRawPtr<SVGElement> replacingElement(svgElement.get());
 683
 684         // Replace <symbol> with <svg>.
 685         ASSERT(element->parentNode());
 686         element->parentNode()->replaceChild(svgElement.release(), element);
 687
 688         // Expand the siblings because the *element* is replaced and we will
 689         // lose the sibling chain when we are back from recursion.
 690         element = replacingElement.get();
 691     }
 692
 693     for (RefPtrWillBeRawPtr<SVGElement> child = Traversal<SVGElement>::firstChild(*element); child; child = Traversal<SVGElement>::nextSibling(*child))
 694         expandSymbolElementsInShadowTree(child.get());
 695 }
 696
 697 void SVGUseElement::invalidateShadowTree()
 698 {
 699     if (!inActiveDocument() || m_needsShadowTreeRecreation)
 700         return;
 701     clearInstanceRoot();
 702     scheduleShadowTreeRecreation();
 703     invalidateDependentShadowTrees();
 704 }
 705
 706 void SVGUseElement::invalidateDependentShadowTrees()
 707 {
 708     // Recursively invalidate dependent <use> shadow trees
 709     const WillBeHeapHashSet<RawPtrWillBeWeakMember<SVGElement>>& instances = instancesForElement();
 710     for (SVGElement* instance : instances) {
 711         if (SVGUseElement* element = instance->correspondingUseElement()) {
 712             ASSERT(element->inDocument());
 713             element->invalidateShadowTree();
 714         }
 715     }
 716 }
 717
 718 void SVGUseElement::transferUseAttributesToReplacedElement(SVGElement* from, SVGElement* to) const
 719 {
 720     ASSERT(from);
 721     ASSERT(to);
 722
 723     to->cloneDataFromElement(*from);
 724
 725     to->removeAttribute(SVGNames::xAttr);
 726     to->removeAttribute(SVGNames::yAttr);
 727     to->removeAttribute(SVGNames::widthAttr);
 728     to->removeAttribute(SVGNames::heightAttr);
 729     to->removeAttribute(XLinkNames::hrefAttr);
 730 }
 731
 732 bool SVGUseElement::selfHasRelativeLengths() const
 733 {
 734     if (m_x->currentValue()->isRelative()
 735         || m_y->currentValue()->isRelative()
 736         || m_width->currentValue()->isRelative()
 737         || m_height->currentValue()->isRelative())
 738         return true;
 739
 740     if (!m_targetElementInstance)
 741         return false;
 742
 743     return m_targetElementInstance->hasRelativeLengths();
 744 }
 745
 746 FloatRect SVGUseElement::getBBox()
 747 {
 748     document().updateLayoutIgnorePendingStylesheets();
 749
 750     if (!layoutObject())
 751         return FloatRect();
 752
 753     LayoutSVGTransformableContainer& transformableContainer = toLayoutSVGTransformableContainer(*layoutObject());
 754     // Don't apply the additional translation if the oBB is invalid.
 755     if (!transformableContainer.isObjectBoundingBoxValid())
 756         return FloatRect();
 757
 758     // TODO(fs): Preferably this would just use objectBoundingBox() (and hence
 759     // don't need to override SVGGraphicsElement::getBBox at all) and be
 760     // correct without additional work. That will not work out ATM without
 761     // additional quirks. The problem stems from including the additional
 762     // translation directly on the LayoutObject corresponding to the
 763     // SVGUseElement.
 764     FloatRect bbox = transformableContainer.objectBoundingBox();
 765     bbox.move(transformableContainer.additionalTranslation());
 766     return bbox;
 767 }
 768
 769 void SVGUseElement::dispatchPendingEvent(SVGUseEventSender* eventSender)
 770 {
 771     ASSERT_UNUSED(eventSender, eventSender == &svgUseLoadEventSender());
 772     ASSERT(isStructurallyExternal() && m_haveFiredLoadEvent);
 773     dispatchEvent(Event::create(EventTypeNames::load));
 774 }
 775
 776 void SVGUseElement::notifyFinished(Resource* resource)
 777 {
 778     if (!inDocument())
 779         return;
 780
 781     invalidateShadowTree();
 782     if (resource->errorOccurred())
 783         dispatchEvent(Event::create(EventTypeNames::error));
 784     else if (!resource->wasCanceled()) {
 785         if (m_haveFiredLoadEvent)
 786             return;
 787         if (!isStructurallyExternal())
 788             return;
 789         ASSERT(!m_haveFiredLoadEvent);
 790         m_haveFiredLoadEvent = true;
 791         svgUseLoadEventSender().dispatchEventSoon(this);
 792     }
 793 }
 794
 795 bool SVGUseElement::resourceIsStillLoading()
 796 {
 797     if (m_resource && m_resource->isLoading())
 798         return true;
 799     return false;
 800 }
 801
 802 bool SVGUseElement::instanceTreeIsLoading(SVGElement* targetInstance)
 803 {
 804     for (SVGElement* element = Traversal<SVGElement>::firstChild(*targetInstance); element; element = Traversal<SVGElement>::nextSibling(*element)) {
 805         if (SVGUseElement* use = element->correspondingUseElement()) {
 806             if (use->resourceIsStillLoading())
 807                 return true;
 808         }
 809         if (element->hasChildren() && instanceTreeIsLoading(element))
 810             return true;
 811     }
 812     return false;
 813 }
 814
 815 void SVGUseElement::setDocumentResource(ResourcePtr<DocumentResource> resource)
 816 {
 817     if (m_resource == resource)
 818         return;
 819
 820     if (m_resource)
 821         m_resource->removeClient(this);
 822
 823     m_resource = resource;
 824     if (m_resource)
 825         m_resource->addClient(this);
 826 }
 827
 828 }