C++ AXObjectCache类代码示例

AccessibilityObject* AccessibilityObject::firstAccessibleObjectFromNode(const Node* node)
{
    if (!node)
        return 0;

    Document* document = node->document();
    if (!document)
        return 0;

    AXObjectCache* cache = document->axObjectCache();

    AccessibilityObject* accessibleObject = cache->getOrCreate(node->renderer());
    while (accessibleObject && accessibleObject->accessibilityIsIgnored()) {
        node = NodeTraversal::next(node);

        while (node && !node->renderer())
            node = NodeTraversal::nextSkippingChildren(node);

        if (!node)
            return 0;

        accessibleObject = cache->getOrCreate(node->renderer());
    }

    return accessibleObject;
}

bool Scrollbar::scroll(ScrollDirection direction, ScrollGranularity granularity, float multiplier)
{
#if HAVE(ACCESSIBILITY)
    if (AXObjectCache::accessibilityEnabled()) {
        if (parent() && parent()->isFrameView()) {
            Document* document = static_cast<FrameView*>(parent())->frame()->document();
            AXObjectCache* cache = document->axObjectCache();
            AccessibilityScrollbar* axObject = static_cast<AccessibilityScrollbar*>(cache->getOrCreate(ScrollBarRole));
            axObject->setScrollbar(this);
            cache->postNotification(axObject, document, AXObjectCache::AXValueChanged, true);
        }
    }
#endif

    // Ignore perpendicular scrolls.
    if ((m_orientation == HorizontalScrollbar) ? (direction == ScrollUp || direction == ScrollDown) : (direction == ScrollLeft || direction == ScrollRight))
        return false;
    float step = 0;
    switch (granularity) {
    case ScrollByLine:     step = m_lineStep;  break;
    case ScrollByPage:     step = m_pageStep;  break;
    case ScrollByDocument: step = m_totalSize; break;
    case ScrollByPixel:    step = m_pixelStep; break;
    }
    if (direction == ScrollUp || direction == ScrollLeft)
        multiplier = -multiplier;
    if (client())
        return client()->scroll(m_orientation, granularity, step, multiplier);

    return setCurrentPos(max(min(m_currentPos + (step * multiplier), static_cast<float>(m_totalSize - m_visibleSize)), 0.0f), NotFromScrollAnimator);
}

static AtkObject* accessibilityRootObjectWrapper(AtkObject* atkObject)
{
    if (!AXObjectCache::accessibilityEnabled())
        AXObjectCache::enableAccessibility();

    WebPageAccessibilityObject* accessible = WEB_PAGE_ACCESSIBILITY_OBJECT(atkObject);
    if (!accessible->m_page)
        return 0;

    Page* corePage = accessible->m_page->corePage();
    if (!corePage)
        return 0;

    Frame& coreFrame = corePage->mainFrame();
    if (!coreFrame.document())
        return 0;

    AXObjectCache* cache = coreFrame.document()->axObjectCache();
    if (!cache)
        return nullptr;

    AccessibilityObject* coreRootObject = cache->rootObject();
    if (!coreRootObject)
        return 0;

    AtkObject* rootObject = coreRootObject->wrapper();
    if (!rootObject || !ATK_IS_OBJECT(rootObject))
        return 0;

    return rootObject;
}

void FrameSelection::notifyAccessibilityForSelectionChange(const AXTextStateChangeIntent&)
{
    if (!AXObjectCache::accessibilityEnabled())
        return;

    if (!m_selection.start().isNotNull() || !m_selection.end().isNotNull())
        return;

    RenderObject* focusedNode = m_selection.end().containerNode()->renderer();
    AXObjectCache* cache = m_frame->document()->existingAXObjectCache();
    if (!cache)
        return;

    AccessibilityObject* accessibilityObject = cache->getOrCreate(focusedNode);
    if (!accessibilityObject)
        return;

    int offset;
    RefPtr<AccessibilityObject> object = objectFocusedAndCaretOffsetUnignored(accessibilityObject, offset);
    if (!object)
        return;

    emitTextSelectionChange(object.get(), m_selection, offset);
    maybeEmitTextFocusChange(WTFMove(object));
}

void AXObjectCache::textMarkerDataForVisiblePosition(TextMarkerData& textMarkerData, const VisiblePosition& visiblePos)
{
    // This memory must be bzero'd so instances of TextMarkerData can be tested for byte-equivalence.
    // This also allows callers to check for failure by looking at textMarkerData upon return.
    memset(&textMarkerData, 0, sizeof(TextMarkerData));
    
    if (visiblePos.isNull())
        return;
    
    Position deepPos = visiblePos.deepEquivalent();
    Node* domNode = deepPos.deprecatedNode();
    ASSERT(domNode);
    if (!domNode)
        return;
    
    if (domNode->isHTMLElement()) {
        HTMLInputElement* inputElement = domNode->toInputElement();
        if (inputElement && inputElement->isPasswordField())
            return;
    }
    
    // find or create an accessibility object for this node
    AXObjectCache* cache = domNode->document()->axObjectCache();
    RefPtr<AccessibilityObject> obj = cache->getOrCreate(domNode);
    
    textMarkerData.axID = obj.get()->axObjectID();
    textMarkerData.node = domNode;
    textMarkerData.offset = deepPos.deprecatedEditingOffset();
    textMarkerData.affinity = visiblePos.affinity();   
    
    cache->setNodeInUse(domNode);
}

bool AXObject::accessibilityIsIgnored() const
{
    AXObjectCache* cache = axObjectCache();
    if (!cache)
        return true;

    AXComputedObjectAttributeCache* attributeCache = cache->computedObjectAttributeCache();
    if (attributeCache) {
        AXObjectInclusion ignored = attributeCache->getIgnored(axObjectID());
        switch (ignored) {
        case IgnoreObject:
            return true;
        case IncludeObject:
            return false;
        case DefaultBehavior:
            break;
        }
    }

    bool result = computeAccessibilityIsIgnored();

    if (attributeCache)
        attributeCache->setIgnored(axObjectID(), result ? IgnoreObject : IncludeObject);

    return result;
}

void AccessibilityARIAGrid::addChildren()
{
    ASSERT(!m_haveChildren); 
    
    if (!isAccessibilityTable()) {
        AccessibilityRenderObject::addChildren();
        return;
    }
    
    m_haveChildren = true;
    if (!m_renderer)
        return;
    
    AXObjectCache* axCache = m_renderer->document().axObjectCache();
    
    // add only rows that are labeled as aria rows
    HashSet<AccessibilityObject*> appendedRows;
    unsigned columnCount = 0;
    for (RefPtr<AccessibilityObject> child = firstChild(); child; child = child->nextSibling())
        addRowDescendant(child.get(), appendedRows, columnCount);
    
    // make the columns based on the number of columns in the first body
    for (unsigned i = 0; i < columnCount; ++i) {
        AccessibilityTableColumn* column = toAccessibilityTableColumn(axCache->getOrCreate(ColumnRole));
        column->setColumnIndex((int)i);
        column->setParent(this);
        m_columns.append(column);
        if (!column->accessibilityIsIgnored())
            m_children.append(column);
    }
    
    AccessibilityObject* headerContainerObject = headerContainer();
    if (headerContainerObject && !headerContainerObject->accessibilityIsIgnored())
        m_children.append(headerContainerObject);
}

void AccessibilityMenuList::didUpdateActiveOption(int optionIndex)
{
    Ref<Document> document(m_renderer->document());
    AXObjectCache* cache = document->axObjectCache();

    const auto& childObjects = children();
    if (!childObjects.isEmpty()) {
        ASSERT(childObjects.size() == 1);
        ASSERT(childObjects[0]->isMenuListPopup());

        // We might be calling this method in situations where the renderers for list items
        // associated to the menu list have not been created (e.g. they might be rendered
        // in the UI process, as it's the case in the GTK+ port, which uses GtkMenuItem).
        // So, we need to make sure that the accessibility popup object has some children
        // before asking it to update its active option, or it will read invalid memory.
        // You can reproduce the issue in the GTK+ port by removing this check and running
        // accessibility/insert-selected-option-into-select-causes-crash.html (will crash).
        int popupChildrenSize = static_cast<int>(childObjects[0]->children().size());
        if (childObjects[0]->isMenuListPopup() && optionIndex >= 0 && optionIndex < popupChildrenSize) {
            if (AccessibilityMenuListPopup* popup = toAccessibilityMenuListPopup(childObjects[0].get()))
                popup->didUpdateActiveOption(optionIndex);
        }
    }

    cache->postNotification(this, &document.get(), AXObjectCache::AXMenuListValueChanged, TargetElement, PostSynchronously);
}

AccessibilityObject* AccessibilityObject::firstAccessibleObjectFromNode(const Node* node)
{
    ASSERT(AXObjectCache::accessibilityEnabled());

    if (!node)
        return 0;

    Document* document = node->document();
    if (!document)
        return 0;

    AXObjectCache* cache = document->axObjectCache();

    AccessibilityObject* accessibleObject = cache->getOrCreate(node->renderer());
    while (accessibleObject && accessibleObject->accessibilityIsIgnored()) {
        node = node->traverseNextNode();

        while (node && !node->renderer())
            node = node->traverseNextSibling();

        if (!node)
            return 0;

        accessibleObject = cache->getOrCreate(node->renderer());
    }

    return accessibleObject;
}

void SimpleEditCommand::notifyAccessibilityForTextChange(Node* node, AXTextEditType type, const String& text, const VisiblePosition& position)
{
    if (!AXObjectCache::accessibilityEnabled())
        return;
    AXObjectCache* cache = document().existingAXObjectCache();
    if (!cache)
        return;
    cache->postTextStateChangeNotification(node, type, text, position);
}

void AccessibilityMenuListPopup::didUpdateActiveOption(int optionIndex)
{
    ASSERT_ARG(optionIndex, optionIndex >= 0);
    ASSERT_ARG(optionIndex, optionIndex < static_cast<int>(m_children.size()));

    AXObjectCache* cache = axObjectCache();
    RefPtr<AccessibilityObject> child = m_children[optionIndex].get();

    cache->postNotification(child.get(), document(), AXObjectCache::AXFocusedUIElementChanged, TargetElement, PostSynchronously);
    cache->postNotification(child.get(), document(), AXObjectCache::AXMenuListItemSelected, TargetElement, PostSynchronously);
}

void EditCommand::postTextStateChangeNotification(AXTextEditType type, const String& text, const VisiblePosition& position)
{
    if (!AXObjectCache::accessibilityEnabled())
        return;
    if (!text.length())
        return;
    AXObjectCache* cache = document().existingAXObjectCache();
    if (!cache)
        return;
    Node* node = highestEditableRoot(position.deepEquivalent(), HasEditableAXRole);
    cache->postTextStateChangeNotification(node, type, text, position);
}

void AccessibilityARIAGrid::addChildren()
{
    ASSERT(!m_haveChildren); 
    
    if (!isAccessibilityTable()) {
        AccessibilityRenderObject::addChildren();
        return;
    }
    
    m_haveChildren = true;
    if (!m_renderer)
        return;
    
    AXObjectCache* axCache = m_renderer->document().axObjectCache();
    
    // Add the children rows but be mindful in case there are footer sections in this table.
    HashSet<AccessibilityObject*> appendedRows;
    unsigned columnCount = 0;
    AccessibilityChildrenVector footerSections;
    for (RefPtr<AccessibilityObject> child = firstChild(); child; child = child->nextSibling()) {
        bool footerSection = false;
        if (RenderObject* childRenderer = child->renderer()) {
            if (childRenderer->isTableSection()) {
                if (RenderTableSection* childSection = toRenderTableSection(childRenderer)) {
                    if (childSection == childSection->table()->footer()) {
                        footerSections.append(child);
                        footerSection = true;
                    }
                }
            }
        }
        if (!footerSection)
            addRowDescendant(child.get(), appendedRows, columnCount);
    }
    
    for (const auto& footerSection : footerSections)
        addRowDescendant(footerSection.get(), appendedRows, columnCount);
    
    // make the columns based on the number of columns in the first body
    for (unsigned i = 0; i < columnCount; ++i) {
        AccessibilityTableColumn* column = toAccessibilityTableColumn(axCache->getOrCreate(ColumnRole));
        column->setColumnIndex((int)i);
        column->setParent(this);
        m_columns.append(column);
        if (!column->accessibilityIsIgnored())
            m_children.append(column);
    }
    
    AccessibilityObject* headerContainerObject = headerContainer();
    if (headerContainerObject && !headerContainerObject->accessibilityIsIgnored())
        m_children.append(headerContainerObject);
}

void TreeScopeAdopter::moveTreeToNewScope(Node& root) const
{
    ASSERT(needsScopeChange());

#if !ENABLE(OILPAN)
    oldScope().guardRef();
#endif

    // If an element is moved from a document and then eventually back again the collection cache for
    // that element may contain stale data as changes made to it will have updated the DOMTreeVersion
    // of the document it was moved to. By increasing the DOMTreeVersion of the donating document here
    // we ensure that the collection cache will be invalidated as needed when the element is moved back.
    Document& oldDocument = oldScope().document();
    Document& newDocument = newScope().document();
    bool willMoveToNewDocument = oldDocument != newDocument;
    AXObjectCache* axObjectCache = oldDocument.existingAXObjectCache();
    if (willMoveToNewDocument)
        oldDocument.incDOMTreeVersion();

    for (Node& node : NodeTraversal::inclusiveDescendantsOf(root)) {
        updateTreeScope(node);

        if (willMoveToNewDocument) {
            if (axObjectCache)
                axObjectCache->remove(&node);
            moveNodeToNewDocument(node, oldDocument, newDocument);
        } else if (node.hasRareData()) {
            NodeRareData* rareData = node.rareData();
            if (rareData->nodeLists())
                rareData->nodeLists()->adoptTreeScope();
        }

        if (!node.isElementNode())
            continue;

        if (node.hasSyntheticAttrChildNodes()) {
            WillBeHeapVector<RefPtrWillBeMember<Attr>>& attrs = *toElement(node).attrNodeList();
            for (unsigned i = 0; i < attrs.size(); ++i)
                moveTreeToNewScope(*attrs[i]);
        }

        for (ShadowRoot* shadow = node.youngestShadowRoot(); shadow; shadow = shadow->olderShadowRoot()) {
            shadow->setParentTreeScope(newScope());
            if (willMoveToNewDocument)
                moveTreeToNewDocument(*shadow, oldDocument, newDocument);
        }
    }

#if !ENABLE(OILPAN)
    oldScope().guardDeref();
#endif
}

AccessibilityScrollbar* AccessibilityScrollView::addChildScrollbar(Scrollbar* scrollbar)
{
    if (!scrollbar)
        return nullptr;
    
    AXObjectCache* cache = axObjectCache();
    if (!cache)
        return nullptr;

    auto& scrollBarObject = downcast<AccessibilityScrollbar>(*cache->getOrCreate(scrollbar));
    scrollBarObject.setParent(this);
    m_children.append(&scrollBarObject);
    return &scrollBarObject;
}