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/*
* 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 "AccessibilitySVGElement.h"
#include "AXObjectCache.h"
#include "ElementIterator.h"
#include "HTMLNames.h"
#include "RenderIterator.h"
#include "RenderText.h"
#include "SVGAElement.h"
#include "SVGDescElement.h"
#include "SVGGElement.h"
#include "SVGTitleElement.h"
#include "SVGUseElement.h"
#include "XLinkNames.h"
#include <wtf/Language.h>
namespace WebCore {
AccessibilitySVGElement::AccessibilitySVGElement(RenderObject* renderer)
: AccessibilityRenderObject(renderer)
{
}
AccessibilitySVGElement::~AccessibilitySVGElement() = default;
Ref<AccessibilitySVGElement> AccessibilitySVGElement::create(RenderObject* renderer)
{
return adoptRef(*new AccessibilitySVGElement(renderer));
}
AccessibilityObject* AccessibilitySVGElement::targetForUseElement() const
{
if (!is<SVGUseElement>(element()))
return nullptr;
SVGUseElement& use = downcast<SVGUseElement>(*element());
String href = use.href();
if (href.isEmpty())
href = getAttribute(HTMLNames::hrefAttr);
Element* target = SVGURIReference::targetElementFromIRIString(href, use.document());
if (target)
return axObjectCache()->getOrCreate(target);
return nullptr;
}
template <typename ChildrenType>
Element* AccessibilitySVGElement::childElementWithMatchingLanguage(ChildrenType& children) const
{
String languageCode = language();
if (languageCode.isEmpty())
languageCode = defaultLanguage();
// The best match for a group of child SVG2 'title' or 'desc' elements may be the one
// which lacks a 'lang' attribute value. However, indexOfBestMatchingLanguageInList()
// currently bases its decision on non-empty strings. Furthermore, we cannot count on
// that child element having a given position. So we'll look for such an element while
// building the language list and save it as our fallback.
Element* fallback = nullptr;
Vector<String> childLanguageCodes;
Vector<Element*> elements;
for (auto& child : children) {
auto& lang = child.attributeWithoutSynchronization(SVGNames::langAttr);
childLanguageCodes.append(lang);
elements.append(&child);
// The current draft of the SVG2 spec states if there are multiple equally-valid
// matches, the first match should be used.
if (lang.isEmpty() && !fallback)
fallback = &child;
}
bool exactMatch;
size_t index = indexOfBestMatchingLanguageInList(languageCode, childLanguageCodes, exactMatch);
if (index < childLanguageCodes.size())
return elements[index];
return fallback;
}
void AccessibilitySVGElement::accessibilityText(Vector<AccessibilityText>& textOrder)
{
String description = accessibilityDescription();
if (!description.isEmpty())
textOrder.append(AccessibilityText(description, AccessibilityTextSource::Alternative));
String helptext = helpText();
if (!helptext.isEmpty())
textOrder.append(AccessibilityText(helptext, AccessibilityTextSource::Help));
}
String AccessibilitySVGElement::accessibilityDescription() const
{
// According to the SVG Accessibility API Mappings spec, the order of priority is:
// 1. aria-labelledby
// 2. aria-label
// 3. a direct child title element (selected according to language)
// 4. xlink:title attribute
// 5. for a use element, the accessible name calculated for the re-used content
// 6. for text container elements, the text content
String ariaDescription = ariaAccessibilityDescription();
if (!ariaDescription.isEmpty())
return ariaDescription;
auto titleElements = childrenOfType<SVGTitleElement>(*element());
if (auto titleChild = childElementWithMatchingLanguage(titleElements))
return titleChild->textContent();
if (is<SVGAElement>(element())) {
auto& xlinkTitle = element()->attributeWithoutSynchronization(XLinkNames::titleAttr);
if (!xlinkTitle.isEmpty())
return xlinkTitle;
}
if (m_renderer->isSVGText()) {
AccessibilityTextUnderElementMode mode;
String text = textUnderElement(mode);
if (!text.isEmpty())
return text;
}
if (is<SVGUseElement>(element())) {
if (AccessibilityObject* target = targetForUseElement())
return target->accessibilityDescription();
}
// FIXME: This is here to not break the svg-image.html test. But 'alt' is not
// listed as a supported attribute of the 'image' element in the SVG spec:
// https://www.w3.org/TR/SVG/struct.html#ImageElement
if (m_renderer->isSVGImage()) {
const AtomicString& alt = getAttribute(HTMLNames::altAttr);
if (!alt.isNull())
return alt;
}
return String();
}
String AccessibilitySVGElement::helpText() const
{
// According to the SVG Accessibility API Mappings spec, the order of priority is:
// 1. aria-describedby
// 2. a direct child desc element
// 3. for a use element, the accessible description calculated for the re-used content
// 4. for text container elements, the text content, if not used for the name
// 5. a direct child title element that provides a tooltip, if not used for the name
String describedBy = ariaDescribedByAttribute();
if (!describedBy.isEmpty())
return describedBy;
auto descriptionElements = childrenOfType<SVGDescElement>(*element());
if (auto descriptionChild = childElementWithMatchingLanguage(descriptionElements))
return descriptionChild->textContent();
if (is<SVGUseElement>(element())) {
AccessibilityObject* target = targetForUseElement();
if (target)
return target->helpText();
}
String description = accessibilityDescription();
if (m_renderer->isSVGText()) {
AccessibilityTextUnderElementMode mode;
String text = textUnderElement(mode);
if (!text.isEmpty() && text != description)
return text;
}
auto titleElements = childrenOfType<SVGTitleElement>(*element());
if (auto titleChild = childElementWithMatchingLanguage(titleElements)) {
if (titleChild->textContent() != description)
return titleChild->textContent();
}
return String();
}
bool AccessibilitySVGElement::computeAccessibilityIsIgnored() 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->isSVGHiddenContainer())
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.
for (const auto& child : childrenOfType<SVGElement>(*element())) {
if ((is<SVGTitleElement>(child) || is<SVGDescElement>(child)))
return false;
}
if (roleValue() == AccessibilityRole::Presentational || inheritsPresentationalRole())
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->isSVGText() || m_renderer->isSVGTextPath()) {
for (auto& child : childrenOfType<RenderText>(downcast<RenderElement>(*m_renderer))) {
if (!child.isAllCollapsibleWhitespace())
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->isSVGShape())
return !(hasAttributesRequiredForInclusion() || canSetFocusAttribute() || element()->hasEventListeners());
return AccessibilityRenderObject::computeAccessibilityIsIgnored();
}
bool AccessibilitySVGElement::inheritsPresentationalRole() const
{
if (canSetFocusAttribute())
return false;
AccessibilityRole role = roleValue();
if (role != AccessibilityRole::SVGTextPath && role != AccessibilityRole::SVGTSpan)
return false;
for (AccessibilityObject* parent = parentObject(); parent; parent = parent->parentObject()) {
if (is<AccessibilityRenderObject>(*parent) && parent->element()->hasTagName(SVGNames::textTag))
return parent->roleValue() == AccessibilityRole::Presentational;
}
return false;
}
AccessibilityRole AccessibilitySVGElement::determineAriaRoleAttribute() const
{
AccessibilityRole 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.
for (const auto& child : childrenOfType<SVGElement>(*element())) {
if ((is<SVGTitleElement>(child) || is<SVGDescElement>(child)))
return AccessibilityRole::Unknown;
}
return role;
}
AccessibilityRole AccessibilitySVGElement::determineAccessibilityRole()
{
if ((m_ariaRole = determineAriaRoleAttribute()) != AccessibilityRole::Unknown)
return m_ariaRole;
Element* svgElement = element();
if (m_renderer->isSVGShape() || m_renderer->isSVGPath() || m_renderer->isSVGImage() || is<SVGUseElement>(svgElement))
return AccessibilityRole::Image;
if (m_renderer->isSVGForeignObject() || is<SVGGElement>(svgElement))
return AccessibilityRole::Group;
if (m_renderer->isSVGText())
return AccessibilityRole::SVGText;
if (m_renderer->isSVGTextPath())
return AccessibilityRole::SVGTextPath;
if (m_renderer->isSVGTSpan())
return AccessibilityRole::SVGTSpan;
if (is<SVGAElement>(svgElement))
return AccessibilityRole::WebCoreLink;
return AccessibilityRenderObject::determineAccessibilityRole();
}
} // namespace WebCore