Source/WebCore/accessibility/AccessibilitySVGObject.cpp - external/github.com/WebKit/webkit - Git at Google

 /*
  * Copyright (C) 2016 Igalia, S.L.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
  *     notice, this list of conditions and the following disclaimer in the
  *     documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */

 #include "config.h"
 #include "AccessibilitySVGObject.h"

 #include "AccessibilityNodeObjectInlines.h"
 #include "AXObjectCacheInlines.h"
 #include "AXUtilities.h"
 #include "AccessibilityObjectInlines.h"
 #include "ElementChildIteratorInlines.h"
 #include "ElementInlines.h"
 #include "HTMLNames.h"
 #include "RenderIterator.h"
 #include "RenderObject.h"
 #include "RenderObjectInlines.h"
 #include "RenderText.h"
 #include "SVGAElement.h"
 #include "SVGDescElement.h"
 #include "SVGElementTypeHelpers.h"
 #include "SVGGElement.h"
 #include "SVGNames.h"
 #include "SVGTitleElement.h"
 #include "SVGUseElement.h"
 #include "TypedElementDescendantIteratorInlines.h"
 #include "XLinkNames.h"
 #include <wtf/Language.h>
 #include <wtf/NeverDestroyed.h>

 namespace WebCore {

 AccessibilitySVGObject::AccessibilitySVGObject(AXID axID, RenderObject& renderer, AXObjectCache& cache, bool isSVGRoot)
     : AccessibilityRenderObject(axID, renderer, cache)
 {
     m_isSVGRoot = isSVGRoot;
 }

 AccessibilitySVGObject::AccessibilitySVGObject(AXID axID, Element& element, AXObjectCache& cache, bool isSVGRoot)
     : AccessibilityRenderObject(axID, element, cache)
 {
     m_isSVGRoot = isSVGRoot;
 }

 AccessibilitySVGObject::~AccessibilitySVGObject() = default;

 Ref<AccessibilitySVGObject> AccessibilitySVGObject::create(AXID axID, RenderObject& renderer, AXObjectCache& cache, bool isSVGRoot)
 {
     return adoptRef(*new AccessibilitySVGObject(axID, renderer, cache, isSVGRoot));
 }

 Ref<AccessibilitySVGObject> AccessibilitySVGObject::create(AXID axID, Element& element, AXObjectCache& cache, bool isSVGRoot)
 {
     return adoptRef(*new AccessibilitySVGObject(axID, element, cache, isSVGRoot));
 }

 AccessibilityObject* AccessibilitySVGObject::targetForUseElement() const
 {
     RefPtr use = dynamicDowncast<SVGUseElement>(element());
     if (!use)
         return nullptr;

     auto href = use->href();
     if (href.isEmpty())
         href = getAttribute(HTMLNames::hrefAttr);

     auto target = SVGURIReference::targetElementFromIRIString(href, Ref { use->treeScopeForSVGReferences() });
     CheckedPtr cache = axObjectCache();
     return cache ? cache->getOrCreate(target.element.get()) : nullptr;
 }

 void AccessibilitySVGObject::accessibilityText(Vector<AccessibilityText>& textOrder) const
 {
     // Compute both description and help text together to avoid redundant language
     // matching, which showed up on samples taken on Speedometer 3.1.
     auto [titleChild, descChild] = matchingTitleAndDescChildren();

     String descriptionText = descriptionFromTitleChild(titleChild.get());
     if (!descriptionText.isEmpty())
         textOrder.append(AccessibilityText(descriptionText, AccessibilityTextSource::Alternative));

     String helptext = helpTextFromChildren(titleChild.get(), descChild.get(), descriptionText);
     if (!helptext.isEmpty())
         textOrder.append(AccessibilityText(WTF::move(helptext), AccessibilityTextSource::Help));
 }

 void AccessibilitySVGObject::alternativeText(Vector<AccessibilityText>& textOrder) const
 {
     // https://w3c.github.io/svg-aam/#mapping_additional_nd
     // Per SVG-AAM §7.1, the accessible name comes from aria-labelledby/aria-label,
     // a <title> child, xlink:title (on <a>), the <use> target, or alt (on <image>).
     // Expose this as Alternative text so host-language parents (e.g. <a> or <button>)
     // pick it up via textUnderElement when deriving their own accname.
     String descriptionText = description();
     if (!descriptionText.isEmpty())
         textOrder.append(AccessibilityText(WTF::move(descriptionText), AccessibilityTextSource::Alternative));
 }

 auto AccessibilitySVGObject::matchingTitleAndDescChildren() const -> MatchingLanguageChildren
 {
     RefPtr element = this->element();
     if (!element)
         return { };

     // Iterate over SVG children once, bucketing <title> and <desc> elements,
     // then do language matching with a single languageIncludingAncestors() call.
     // This is an optimization based on a profile taken on Speedometer.
     Vector<String> titleLangs;
     Vector<Element*> titleElements;
     RefPtr<Element> titleFallback;
     bool hasTitleWithLang = false;
     Vector<String> descLangs;
     Vector<Element*> descElements;
     RefPtr<Element> descFallback;
     bool hasDescWithLang = false;

     for (Ref child : childrenOfType<SVGElement>(*element)) {
         const auto& lang = child->attributeWithoutSynchronization(SVGNames::langAttr);
         if (is<SVGTitleElement>(child.get())) {
             titleLangs.append(lang);
             titleElements.append(const_cast<Element*>(static_cast<const Element*>(child.ptr())));
             if (lang.isEmpty()) {
                 if (!titleFallback)
                     titleFallback = child.ptr();
             } else
                 hasTitleWithLang = true;
         } else if (is<SVGDescElement>(child.get())) {
             descLangs.append(lang);
             descElements.append(const_cast<Element*>(static_cast<const Element*>(child.ptr())));
             if (lang.isEmpty()) {
                 if (!descFallback)
                     descFallback = child.ptr();
             } else
                 hasDescWithLang = true;
         }
     }

     // If no child has a lang attribute, language matching can't improve on the
     // fallback. Skip the expensive languageIncludingAncestors() and NSLocale calls.
     if (!hasTitleWithLang && !hasDescWithLang)
         return { WTF::move(titleFallback), WTF::move(descFallback) };

     String languageCode = languageIncludingAncestors();
     if (languageCode.isEmpty())
         languageCode = defaultLanguage();

     auto matchInList = [&](Vector<String>& langs, Vector<Element*>& elements, RefPtr<Element>& fallback) -> RefPtr<Element> {
         bool exactMatch;
         size_t index = indexOfBestMatchingLanguageInList(languageCode, langs, exactMatch);
         if (index < langs.size())
             return elements[index];
         return fallback;
     };

     RefPtr titleChild = hasTitleWithLang ? matchInList(titleLangs, titleElements, titleFallback) : WTF::move(titleFallback);
     RefPtr descChild = hasDescWithLang ? matchInList(descLangs, descElements, descFallback) : WTF::move(descFallback);
     return { WTF::move(titleChild), WTF::move(descChild) };
 }

 String AccessibilitySVGObject::descriptionFromTitleChild(Element* titleChild) const
 {
     // Priority per SVG AAM: aria-labelledby/label, title child, xlink:title, use target, alt.
     String result = ariaAccessibilityDescription();
     if (!result.isEmpty())
         return result;

     if (titleChild) {
         result = titleChild->textContent();
         if (!result.isEmpty())
             return result;
     }

     RefPtr element = this->element();
     if (is<SVGAElement>(element.get())) {
         const auto& xlinkTitle = element->attributeWithoutSynchronization(XLinkNames::titleAttr);
         if (!xlinkTitle.isEmpty())
             return xlinkTitle;
     }

     if (RefPtr target = targetForUseElement()) {
         // Avoid infinite recursion from circular <use> references by tracking ones we're currently resolving.
         static NeverDestroyed<HashSet<Element*>> elementsResolvingDescription;
         if (elementsResolvingDescription->add(element.get()).isNewEntry) {
             auto result = target->description();
             elementsResolvingDescription->remove(element.get());
             return result;
         }
     }

     if (m_renderer && m_renderer->isRenderOrLegacyRenderSVGImage()) {
         const auto& alt = getAttribute(HTMLNames::altAttr);
         if (!alt.isNull())
             return alt;
     }

     return { };
 }

 String AccessibilitySVGObject::helpTextFromChildren(Element* titleChild, Element* descChild, const String& descriptionText) const
 {
     // Priority per SVG AAM: aria-describedby, desc child, use target, title child (if != description).
     RefPtr element = this->element();
     if (!element)
         return { };

     String result = ariaDescribedByAttribute();
     if (!result.isEmpty())
         return result;

     if (descChild) {
         result = descChild->textContent();
         if (!result.isEmpty())
             return result;
     }

     if (RefPtr target = targetForUseElement()) {
         // Avoid infinite recursion from circular <use> references by tracking ones we're currently resolving.
         static NeverDestroyed<HashSet<Element*>> elementsResolvingHelpText;
         if (elementsResolvingHelpText->add(element.get()).isNewEntry) {
             auto result = target->helpText();
             elementsResolvingHelpText->remove(element.get());
             return result;
         }
     }

     if (titleChild) {
         auto titleText = titleChild->textContent();
         if (titleText != descriptionText)
             return titleText;
     }

     return { };
 }

 String AccessibilitySVGObject::description() const
 {
     auto [titleChild, descChild] = matchingTitleAndDescChildren();
     return descriptionFromTitleChild(titleChild.get());
 }

 String AccessibilitySVGObject::helpText() const
 {
     auto [titleChild, descChild] = matchingTitleAndDescChildren();
     String descriptionText = descriptionFromTitleChild(titleChild.get());
     return helpTextFromChildren(titleChild.get(), descChild.get(), descriptionText);
 }

 bool AccessibilitySVGObject::hasTitleOrDescriptionChild() const
 {
     RefPtr element = this->element();
     if (!element)
         return false;

     for (const auto& child : childrenOfType<SVGElement>(*element)) {
         if (is<SVGTitleElement>(child) || is<SVGDescElement>(child))
             return true;
     }
     return false;
 }

 bool AccessibilitySVGObject::computeIsIgnored() const
 {
     // According to the SVG Accessibility API Mappings spec, items should be excluded if:
     // * They would be excluded according to the Core Accessibility API Mappings.
     // * They are neither perceivable nor interactive.
     // * Their first mappable role is presentational, unless they have a global ARIA
     //   attribute (covered by Core AAM) or at least one 'title' or 'desc' child element.
     // * They have an ancestor with Children Presentational: True (covered by Core AAM)

     AccessibilityObjectInclusion decision = defaultObjectInclusion();
     if (decision == AccessibilityObjectInclusion::IgnoreObject)
         return true;

     if (!m_renderer || m_renderer->isLegacyRenderSVGHiddenContainer() || m_renderer->isRenderSVGHiddenContainer())
         return true;

     // The SVG AAM states objects with at least one 'title' or 'desc' element MUST be included.
     // At this time, the presence of a matching 'lang' attribute is not mentioned in the spec.
     if (hasTitleOrDescriptionChild())
         return false;

     if (ignoredFromPresentationalRole())
         return true;

     if (ariaRoleAttribute() != AccessibilityRole::Unknown)
         return false;

     // The SVG AAM states text elements should also be included, if they have content.
     if (m_renderer->isRenderSVGText() || m_renderer->isRenderSVGTextPath()) {
         for (CheckedRef child : childrenOfType<RenderText>(downcast<RenderElement>(*m_renderer))) {
             if (!child->containsOnlyCollapsibleWhitespace())
                 return false;
         }
     }

     // SVG shapes should not be included unless there's a concrete reason for inclusion.
     // https://rawgit.com/w3c/aria/master/svg-aam/svg-aam.html#exclude_elements
     if (m_renderer->isRenderOrLegacyRenderSVGShape()) {
         if (canSetFocusAttribute() || element()->hasEventListeners())
             return false;
         if (RefPtr svgParent = Accessibility::findAncestor<AccessibilityObject>(*this, true, [] (const AccessibilityObject& object) {
             return object.hasAttributesRequiredForInclusion() || object.isAccessibilitySVGRoot();
         }))
             return !svgParent->hasAttributesRequiredForInclusion();
         return true;
     }

     return AccessibilityRenderObject::computeIsIgnored();
 }

 bool AccessibilitySVGObject::inheritsPresentationalRole() const
 {
     if (canSetFocusAttribute())
         return false;

     auto role = this->role();
     if (role != AccessibilityRole::SVGTextPath && role != AccessibilityRole::SVGTSpan)
         return false;

     for (RefPtr parent = parentObject(); parent; parent = parent->parentObject()) {
         if (is<AccessibilityRenderObject>(*parent) && parent->hasElementName(ElementName::SVG_text))
             return parent->role() == AccessibilityRole::Presentational;
     }

     return false;
 }

 AccessibilityRole AccessibilitySVGObject::determineAriaRoleAttribute() const
 {
     auto role = AccessibilityRenderObject::determineAriaRoleAttribute();
     if (role != AccessibilityRole::Presentational)
         return role;

     // The presence of a 'title' or 'desc' child element trumps PresentationalRole.
     // https://lists.w3.org/Archives/Public/public-svg-a11y/2016Apr/0016.html
     // At this time, the presence of a matching 'lang' attribute is not mentioned.
     return hasTitleOrDescriptionChild() ? AccessibilityRole::Unknown : role;
 }

 AccessibilityRole AccessibilitySVGObject::determineAccessibilityRole()
 {
     if (m_ariaRole != AccessibilityRole::Unknown)
         return m_ariaRole;

     RefPtr element = this->element();
     if (is<SVGGElement>(element)) {
         // https://w3c.github.io/svg-aam/#include_elements
         // g elements are generic (like a div) unless they have a name or is focusable.
         // Evaluated before the renderer check so display:contents <g> still exposes its role.
         if (WebCore::hasAccNameAttribute(*element) || hasTitleOrDescriptionChild() || canSetFocusAttribute())
             return AccessibilityRole::Group;
         return AccessibilityRole::Generic;
     }

     if (!m_renderer)
         return AccessibilityRole::Unknown;

     if (isAccessibilitySVGRoot())
         return AccessibilityRole::Generic;

     if (m_renderer->isRenderOrLegacyRenderSVGShape() || m_renderer->isRenderOrLegacyRenderSVGPath() || m_renderer->isRenderOrLegacyRenderSVGImage() || is<SVGUseElement>(element))
         return AccessibilityRole::Image;
     if (m_renderer->isRenderOrLegacyRenderSVGForeignObject())
         return AccessibilityRole::Generic;
     if (m_renderer->isRenderSVGInlineText())
         return AccessibilityRole::StaticText;
     if (m_renderer->isRenderSVGText())
         return AccessibilityRole::SVGText;
     if (m_renderer->isRenderSVGTextPath())
         return AccessibilityRole::SVGTextPath;
     if (m_renderer->isRenderSVGTSpan())
         return AccessibilityRole::SVGTSpan;
     if (is<SVGAElement>(element)) {
         if (element->isLink() || hasClickHandler())
             return AccessibilityRole::Link;
     }

     return AccessibilityRenderObject::determineAccessibilityRole();
 }

 AccessibilityObject* AccessibilitySVGObject::parentObject() const
 {
     if (m_parent) {
         // If a parent was set because this is a remote SVG resource, use that.
         AX_ASSERT(m_isSVGRoot);
         return m_parent.get();
     }

     // Otherwise, we should rely on the standard render tree for the parent.
     return AccessibilityRenderObject::parentObject();
 }

 bool AccessibilitySVGObject::isRootWithAccessibleContent() const
 {
     if (!isAccessibilitySVGRoot())
         return false;

     RefPtr rootElement = this->element();
     if (!rootElement)
         return false;

     auto isAccessibleSVGElement = [] (const SVGElement& element) -> bool {
         // The presence of an SVGTitle or SVGDesc element is enough to deem the SVG hierarchy as accessible.
         if (is<SVGTitleElement>(element)
             || is<SVGDescElement>(element))
             return true;

         // Text content is accessible.
         if (element.isTextContent())
             return true;

         // If the role or aria-label attributes are specified, this is accessible.
         if (!element.attributeWithoutSynchronization(HTMLNames::roleAttr).isEmpty()
             || !element.attributeWithoutSynchronization(HTMLNames::aria_labelAttr).isEmpty())
             return true;

         return false;
     };

     RefPtr svgRootElement = dynamicDowncast<SVGElement>(*rootElement);
     if (svgRootElement && isAccessibleSVGElement(*svgRootElement))
         return true;

     // This SVG hierarchy is accessible if any of its descendants is accessible.
     for (const Ref descendant : descendantsOfType<SVGElement>(*rootElement)) {
         if (isAccessibleSVGElement(descendant.get()))
             return true;
     }

     return false;
 }

 } // namespace WebCore
	/*
	* Copyright (C) 2016 Igalia, S.L.
	* All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	*
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution.
	*
	* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
	* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
	* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
	* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
	* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
	* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
	* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*/

	#include "config.h"
	#include "AccessibilitySVGObject.h"

	#include "AccessibilityNodeObjectInlines.h"
	#include "AXObjectCacheInlines.h"
	#include "AXUtilities.h"
	#include "AccessibilityObjectInlines.h"
	#include "ElementChildIteratorInlines.h"
	#include "ElementInlines.h"
	#include "HTMLNames.h"
	#include "RenderIterator.h"
	#include "RenderObject.h"
	#include "RenderObjectInlines.h"
	#include "RenderText.h"
	#include "SVGAElement.h"
	#include "SVGDescElement.h"
	#include "SVGElementTypeHelpers.h"
	#include "SVGGElement.h"
	#include "SVGNames.h"
	#include "SVGTitleElement.h"
	#include "SVGUseElement.h"
	#include "TypedElementDescendantIteratorInlines.h"
	#include "XLinkNames.h"
	#include <wtf/Language.h>
	#include <wtf/NeverDestroyed.h>

	namespace WebCore {

	AccessibilitySVGObject::AccessibilitySVGObject(AXID axID, RenderObject& renderer, AXObjectCache& cache, bool isSVGRoot)
	: AccessibilityRenderObject(axID, renderer, cache)
	{
	m_isSVGRoot = isSVGRoot;
	}

	AccessibilitySVGObject::AccessibilitySVGObject(AXID axID, Element& element, AXObjectCache& cache, bool isSVGRoot)
	: AccessibilityRenderObject(axID, element, cache)
	{
	m_isSVGRoot = isSVGRoot;
	}

	AccessibilitySVGObject::~AccessibilitySVGObject() = default;

	Ref<AccessibilitySVGObject> AccessibilitySVGObject::create(AXID axID, RenderObject& renderer, AXObjectCache& cache, bool isSVGRoot)
	{
	return adoptRef(*new AccessibilitySVGObject(axID, renderer, cache, isSVGRoot));
	}

	Ref<AccessibilitySVGObject> AccessibilitySVGObject::create(AXID axID, Element& element, AXObjectCache& cache, bool isSVGRoot)
	{
	return adoptRef(*new AccessibilitySVGObject(axID, element, cache, isSVGRoot));
	}

	AccessibilityObject* AccessibilitySVGObject::targetForUseElement() const
	{
	RefPtr use = dynamicDowncast<SVGUseElement>(element());
	if (!use)
	return nullptr;

	auto href = use->href();
	if (href.isEmpty())
	href = getAttribute(HTMLNames::hrefAttr);

	auto target = SVGURIReference::targetElementFromIRIString(href, Ref { use->treeScopeForSVGReferences() });
	CheckedPtr cache = axObjectCache();
	return cache ? cache->getOrCreate(target.element.get()) : nullptr;
	}

	void AccessibilitySVGObject::accessibilityText(Vector<AccessibilityText>& textOrder) const
	{
	// Compute both description and help text together to avoid redundant language
	// matching, which showed up on samples taken on Speedometer 3.1.
	auto [titleChild, descChild] = matchingTitleAndDescChildren();

	String descriptionText = descriptionFromTitleChild(titleChild.get());
	if (!descriptionText.isEmpty())
	textOrder.append(AccessibilityText(descriptionText, AccessibilityTextSource::Alternative));

	String helptext = helpTextFromChildren(titleChild.get(), descChild.get(), descriptionText);
	if (!helptext.isEmpty())
	textOrder.append(AccessibilityText(WTF::move(helptext), AccessibilityTextSource::Help));
	}

	void AccessibilitySVGObject::alternativeText(Vector<AccessibilityText>& textOrder) const
	{
	// https://w3c.github.io/svg-aam/#mapping_additional_nd
	// Per SVG-AAM §7.1, the accessible name comes from aria-labelledby/aria-label,
	// a <title> child, xlink:title (on <a>), the <use> target, or alt (on <image>).
	// Expose this as Alternative text so host-language parents (e.g. <a> or <button>)
	// pick it up via textUnderElement when deriving their own accname.
	String descriptionText = description();
	if (!descriptionText.isEmpty())
	textOrder.append(AccessibilityText(WTF::move(descriptionText), AccessibilityTextSource::Alternative));
	}

	auto AccessibilitySVGObject::matchingTitleAndDescChildren() const -> MatchingLanguageChildren
	{
	RefPtr element = this->element();
	if (!element)
	return { };

	// Iterate over SVG children once, bucketing <title> and <desc> elements,
	// then do language matching with a single languageIncludingAncestors() call.
	// This is an optimization based on a profile taken on Speedometer.
	Vector<String> titleLangs;
	Vector<Element*> titleElements;
	RefPtr<Element> titleFallback;
	bool hasTitleWithLang = false;
	Vector<String> descLangs;
	Vector<Element*> descElements;
	RefPtr<Element> descFallback;
	bool hasDescWithLang = false;

	for (Ref child : childrenOfType<SVGElement>(*element)) {
	const auto& lang = child->attributeWithoutSynchronization(SVGNames::langAttr);
	if (is<SVGTitleElement>(child.get())) {
	titleLangs.append(lang);
	titleElements.append(const_cast<Element>(static_cast<const Element>(child.ptr())));
	if (lang.isEmpty()) {
	if (!titleFallback)
	titleFallback = child.ptr();
	} else
	hasTitleWithLang = true;
	} else if (is<SVGDescElement>(child.get())) {
	descLangs.append(lang);
	descElements.append(const_cast<Element>(static_cast<const Element>(child.ptr())));
	if (lang.isEmpty()) {
	if (!descFallback)
	descFallback = child.ptr();
	} else
	hasDescWithLang = true;
	}
	}

	// If no child has a lang attribute, language matching can't improve on the
	// fallback. Skip the expensive languageIncludingAncestors() and NSLocale calls.
	if (!hasTitleWithLang && !hasDescWithLang)
	return { WTF::move(titleFallback), WTF::move(descFallback) };

	String languageCode = languageIncludingAncestors();
	if (languageCode.isEmpty())
	languageCode = defaultLanguage();

	auto matchInList = [&](Vector<String>& langs, Vector<Element*>& elements, RefPtr<Element>& fallback) -> RefPtr<Element> {
	bool exactMatch;
	size_t index = indexOfBestMatchingLanguageInList(languageCode, langs, exactMatch);
	if (index < langs.size())
	return elements[index];
	return fallback;
	};

	RefPtr titleChild = hasTitleWithLang ? matchInList(titleLangs, titleElements, titleFallback) : WTF::move(titleFallback);
	RefPtr descChild = hasDescWithLang ? matchInList(descLangs, descElements, descFallback) : WTF::move(descFallback);
	return { WTF::move(titleChild), WTF::move(descChild) };
	}

	String AccessibilitySVGObject::descriptionFromTitleChild(Element* titleChild) const
	{
	// Priority per SVG AAM: aria-labelledby/label, title child, xlink:title, use target, alt.
	String result = ariaAccessibilityDescription();
	if (!result.isEmpty())
	return result;

	if (titleChild) {
	result = titleChild->textContent();
	if (!result.isEmpty())
	return result;
	}

	RefPtr element = this->element();
	if (is<SVGAElement>(element.get())) {
	const auto& xlinkTitle = element->attributeWithoutSynchronization(XLinkNames::titleAttr);
	if (!xlinkTitle.isEmpty())
	return xlinkTitle;
	}

	if (RefPtr target = targetForUseElement()) {
	// Avoid infinite recursion from circular <use> references by tracking ones we're currently resolving.
	static NeverDestroyed<HashSet<Element*>> elementsResolvingDescription;
	if (elementsResolvingDescription->add(element.get()).isNewEntry) {
	auto result = target->description();
	elementsResolvingDescription->remove(element.get());
	return result;
	}
	}

	if (m_renderer && m_renderer->isRenderOrLegacyRenderSVGImage()) {
	const auto& alt = getAttribute(HTMLNames::altAttr);
	if (!alt.isNull())
	return alt;
	}

	return { };
	}

	String AccessibilitySVGObject::helpTextFromChildren(Element* titleChild, Element* descChild, const String& descriptionText) const
	{
	// Priority per SVG AAM: aria-describedby, desc child, use target, title child (if != description).
	RefPtr element = this->element();
	if (!element)
	return { };

	String result = ariaDescribedByAttribute();
	if (!result.isEmpty())
	return result;

	if (descChild) {
	result = descChild->textContent();
	if (!result.isEmpty())
	return result;
	}

	if (RefPtr target = targetForUseElement()) {
	// Avoid infinite recursion from circular <use> references by tracking ones we're currently resolving.
	static NeverDestroyed<HashSet<Element*>> elementsResolvingHelpText;
	if (elementsResolvingHelpText->add(element.get()).isNewEntry) {
	auto result = target->helpText();
	elementsResolvingHelpText->remove(element.get());
	return result;
	}
	}

	if (titleChild) {
	auto titleText = titleChild->textContent();
	if (titleText != descriptionText)
	return titleText;
	}

	return { };
	}

	String AccessibilitySVGObject::description() const
	{
	auto [titleChild, descChild] = matchingTitleAndDescChildren();
	return descriptionFromTitleChild(titleChild.get());
	}

	String AccessibilitySVGObject::helpText() const
	{
	auto [titleChild, descChild] = matchingTitleAndDescChildren();
	String descriptionText = descriptionFromTitleChild(titleChild.get());
	return helpTextFromChildren(titleChild.get(), descChild.get(), descriptionText);
	}

	bool AccessibilitySVGObject::hasTitleOrDescriptionChild() const
	{
	RefPtr element = this->element();
	if (!element)
	return false;

	for (const auto& child : childrenOfType<SVGElement>(*element)) {
	if (is<SVGTitleElement>(child) \|\| is<SVGDescElement>(child))
	return true;
	}
	return false;
	}

	bool AccessibilitySVGObject::computeIsIgnored() const
	{
	// According to the SVG Accessibility API Mappings spec, items should be excluded if:
	// * They would be excluded according to the Core Accessibility API Mappings.
	// * They are neither perceivable nor interactive.
	// * Their first mappable role is presentational, unless they have a global ARIA
	// attribute (covered by Core AAM) or at least one 'title' or 'desc' child element.
	// * They have an ancestor with Children Presentational: True (covered by Core AAM)

	AccessibilityObjectInclusion decision = defaultObjectInclusion();
	if (decision == AccessibilityObjectInclusion::IgnoreObject)
	return true;

	if (!m_renderer \|\| m_renderer->isLegacyRenderSVGHiddenContainer() \|\| m_renderer->isRenderSVGHiddenContainer())
	return true;

	// The SVG AAM states objects with at least one 'title' or 'desc' element MUST be included.
	// At this time, the presence of a matching 'lang' attribute is not mentioned in the spec.
	if (hasTitleOrDescriptionChild())
	return false;

	if (ignoredFromPresentationalRole())
	return true;

	if (ariaRoleAttribute() != AccessibilityRole::Unknown)
	return false;

	// The SVG AAM states text elements should also be included, if they have content.
	if (m_renderer->isRenderSVGText() \|\| m_renderer->isRenderSVGTextPath()) {
	for (CheckedRef child : childrenOfType<RenderText>(downcast<RenderElement>(*m_renderer))) {
	if (!child->containsOnlyCollapsibleWhitespace())
	return false;
	}
	}

	// SVG shapes should not be included unless there's a concrete reason for inclusion.
	// https://rawgit.com/w3c/aria/master/svg-aam/svg-aam.html#exclude_elements
	if (m_renderer->isRenderOrLegacyRenderSVGShape()) {
	if (canSetFocusAttribute() \|\| element()->hasEventListeners())
	return false;
	if (RefPtr svgParent = Accessibility::findAncestor<AccessibilityObject>(*this, true, [] (const AccessibilityObject& object) {
	return object.hasAttributesRequiredForInclusion() \|\| object.isAccessibilitySVGRoot();
	}))
	return !svgParent->hasAttributesRequiredForInclusion();
	return true;
	}

	return AccessibilityRenderObject::computeIsIgnored();
	}

	bool AccessibilitySVGObject::inheritsPresentationalRole() const
	{
	if (canSetFocusAttribute())
	return false;

	auto role = this->role();
	if (role != AccessibilityRole::SVGTextPath && role != AccessibilityRole::SVGTSpan)
	return false;

	for (RefPtr parent = parentObject(); parent; parent = parent->parentObject()) {
	if (is<AccessibilityRenderObject>(*parent) && parent->hasElementName(ElementName::SVG_text))
	return parent->role() == AccessibilityRole::Presentational;
	}

	return false;
	}

	AccessibilityRole AccessibilitySVGObject::determineAriaRoleAttribute() const
	{
	auto role = AccessibilityRenderObject::determineAriaRoleAttribute();
	if (role != AccessibilityRole::Presentational)
	return role;

	// The presence of a 'title' or 'desc' child element trumps PresentationalRole.
	// https://lists.w3.org/Archives/Public/public-svg-a11y/2016Apr/0016.html
	// At this time, the presence of a matching 'lang' attribute is not mentioned.
	return hasTitleOrDescriptionChild() ? AccessibilityRole::Unknown : role;
	}

	AccessibilityRole AccessibilitySVGObject::determineAccessibilityRole()
	{
	if (m_ariaRole != AccessibilityRole::Unknown)
	return m_ariaRole;

	RefPtr element = this->element();
	if (is<SVGGElement>(element)) {
	// https://w3c.github.io/svg-aam/#include_elements
	// g elements are generic (like a div) unless they have a name or is focusable.
	// Evaluated before the renderer check so display:contents <g> still exposes its role.
	if (WebCore::hasAccNameAttribute(*element) \|\| hasTitleOrDescriptionChild() \|\| canSetFocusAttribute())
	return AccessibilityRole::Group;
	return AccessibilityRole::Generic;
	}

	if (!m_renderer)
	return AccessibilityRole::Unknown;

	if (isAccessibilitySVGRoot())
	return AccessibilityRole::Generic;

	if (m_renderer->isRenderOrLegacyRenderSVGShape() \|\| m_renderer->isRenderOrLegacyRenderSVGPath() \|\| m_renderer->isRenderOrLegacyRenderSVGImage() \|\| is<SVGUseElement>(element))
	return AccessibilityRole::Image;
	if (m_renderer->isRenderOrLegacyRenderSVGForeignObject())
	return AccessibilityRole::Generic;
	if (m_renderer->isRenderSVGInlineText())
	return AccessibilityRole::StaticText;
	if (m_renderer->isRenderSVGText())
	return AccessibilityRole::SVGText;
	if (m_renderer->isRenderSVGTextPath())
	return AccessibilityRole::SVGTextPath;
	if (m_renderer->isRenderSVGTSpan())
	return AccessibilityRole::SVGTSpan;
	if (is<SVGAElement>(element)) {
	if (element->isLink() \|\| hasClickHandler())
	return AccessibilityRole::Link;
	}

	return AccessibilityRenderObject::determineAccessibilityRole();
	}

	AccessibilityObject* AccessibilitySVGObject::parentObject() const
	{
	if (m_parent) {
	// If a parent was set because this is a remote SVG resource, use that.
	AX_ASSERT(m_isSVGRoot);
	return m_parent.get();
	}

	// Otherwise, we should rely on the standard render tree for the parent.
	return AccessibilityRenderObject::parentObject();
	}

	bool AccessibilitySVGObject::isRootWithAccessibleContent() const
	{
	if (!isAccessibilitySVGRoot())
	return false;

	RefPtr rootElement = this->element();
	if (!rootElement)
	return false;

	auto isAccessibleSVGElement = [] (const SVGElement& element) -> bool {
	// The presence of an SVGTitle or SVGDesc element is enough to deem the SVG hierarchy as accessible.
	if (is<SVGTitleElement>(element)
	\|\| is<SVGDescElement>(element))
	return true;

	// Text content is accessible.
	if (element.isTextContent())
	return true;

	// If the role or aria-label attributes are specified, this is accessible.
	if (!element.attributeWithoutSynchronization(HTMLNames::roleAttr).isEmpty()
	\|\| !element.attributeWithoutSynchronization(HTMLNames::aria_labelAttr).isEmpty())
	return true;

	return false;
	};

	RefPtr svgRootElement = dynamicDowncast<SVGElement>(*rootElement);
	if (svgRootElement && isAccessibleSVGElement(*svgRootElement))
	return true;

	// This SVG hierarchy is accessible if any of its descendants is accessible.
	for (const Ref descendant : descendantsOfType<SVGElement>(*rootElement)) {
	if (isAccessibleSVGElement(descendant.get()))
	return true;
	}

	return false;
	}

	} // namespace WebCore