element.cpp

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    if (FrameView* view = document()->view()) {
        IntRect visibleContentRect = view->visibleContentRect();
        for (size_t i = 0; i < quads.size(); ++i)
            quads[i].move(-visibleContentRect.x(), -visibleContentRect.y());
    }

    return ClientRectList::create(quads);
}

PassRefPtr<ClientRect> Element::getBoundingClientRect() const
{
    document()->updateLayoutIgnorePendingStylesheets();
    RenderBoxModelObject* renderBoxModelObject = this->renderBoxModelObject();
    if (!renderBoxModelObject)
        return ClientRect::create();

    Vector<FloatQuad> quads;
    renderBoxModelObject->absoluteQuads(quads);

    if (quads.isEmpty())
        return ClientRect::create();

    IntRect result = quads[0].enclosingBoundingBox();
    for (size_t i = 1; i < quads.size(); ++i)
        result.unite(quads[i].enclosingBoundingBox());

    if (FrameView* view = document()->view()) {
        IntRect visibleContentRect = view->visibleContentRect();
        result.move(-visibleContentRect.x(), -visibleContentRect.y());
    }

    return ClientRect::create(result);
}

static inline bool shouldIgnoreAttributeCase(const Element* e)
{
    return e && e->document()->isHTMLDocument() && e->isHTMLElement();
}

const AtomicString& Element::getAttribute(const String& name) const
{
    String localName = shouldIgnoreAttributeCase(this) ? name.lower() : name;
    if (localName == styleAttr.localName() && !m_isStyleAttributeValid)
        updateStyleAttribute();

#if ENABLE(SVG)
    if (!m_areSVGAttributesValid)
        updateAnimatedSVGAttribute(name);
#endif

    if (namedAttrMap)
        if (Attribute* a = namedAttrMap->getAttributeItem(name, shouldIgnoreAttributeCase(this)))
            return a->value();
    
    return nullAtom;
}

const AtomicString& Element::getAttributeNS(const String& namespaceURI, const String& localName) const
{
    return getAttribute(QualifiedName(nullAtom, localName, namespaceURI));
}

void Element::setAttribute(const AtomicString& name, const AtomicString& value, ExceptionCode& ec)
{
    if (!Document::isValidName(name)) {
        ec = INVALID_CHARACTER_ERR;
        return;
    }

    const AtomicString& localName = (shouldIgnoreAttributeCase(this) && !name.string().impl()->isLower()) ? AtomicString(name.string().lower()) : name;

    // allocate attributemap if necessary
    Attribute* old = attributes(false)->getAttributeItem(localName, false);

    document()->incDOMTreeVersion();

    if (localName == idAttr.localName())
        updateId(old ? old->value() : nullAtom, value);
    
    if (old && value.isNull())
        namedAttrMap->removeAttribute(old->name());
    else if (!old && !value.isNull())
        namedAttrMap->addAttribute(createAttribute(QualifiedName(nullAtom, localName, nullAtom), value));
    else if (old && !value.isNull()) {
        old->setValue(value);
        attributeChanged(old);
    }
}

void Element::setAttribute(const QualifiedName& name, const AtomicString& value, ExceptionCode&)
{
    document()->incDOMTreeVersion();

    // allocate attributemap if necessary
    Attribute* old = attributes(false)->getAttributeItem(name);

    if (name == idAttr)
        updateId(old ? old->value() : nullAtom, value);
    
    if (old && value.isNull())
        namedAttrMap->removeAttribute(name);
    else if (!old && !value.isNull())
        namedAttrMap->addAttribute(createAttribute(name, value));
    else if (old) {
        old->setValue(value);
        attributeChanged(old);
    }
}

PassRefPtr<Attribute> Element::createAttribute(const QualifiedName& name, const AtomicString& value)
{
    return Attribute::create(name, value);
}

void Element::attributeChanged(Attribute* attr, bool)
{
    if (!document()->axObjectCache()->accessibilityEnabled())
        return;

    const QualifiedName& attrName = attr->name();
    if (attrName == aria_activedescendantAttr) {
        // any change to aria-activedescendant attribute triggers accessibility focus change, but document focus remains intact
        document()->axObjectCache()->handleActiveDescendantChanged(renderer());
    } else if (attrName == roleAttr) {
        // the role attribute can change at any time, and the AccessibilityObject must pick up these changes
        document()->axObjectCache()->handleAriaRoleChanged(renderer());
    }
}

void Element::setAttributeMap(PassRefPtr<NamedAttrMap> list)
{
    document()->incDOMTreeVersion();

    // If setting the whole map changes the id attribute, we need to call updateId.

    Attribute* oldId = namedAttrMap ? namedAttrMap->getAttributeItem(idAttr) : 0;
    Attribute* newId = list ? list->getAttributeItem(idAttr) : 0;

    if (oldId || newId)
        updateId(oldId ? oldId->value() : nullAtom, newId ? newId->value() : nullAtom);

    if (namedAttrMap)
        namedAttrMap->m_element = 0;

    namedAttrMap = list;

    if (namedAttrMap) {
        namedAttrMap->m_element = this;
        unsigned len = namedAttrMap->length();
        for (unsigned i = 0; i < len; i++)
            attributeChanged(namedAttrMap->m_attributes[i].get());
        // FIXME: What about attributes that were in the old map that are not in the new map?
    }
}

bool Element::hasAttributes() const
{
    if (!m_isStyleAttributeValid)
        updateStyleAttribute();

#if ENABLE(SVG)
    if (!m_areSVGAttributesValid)
        updateAnimatedSVGAttribute(String());
#endif

    return namedAttrMap && namedAttrMap->length() > 0;
}

String Element::nodeName() const
{
    return m_tagName.toString();
}

String Element::nodeNamePreservingCase() const
{
    return m_tagName.toString();
}

void Element::setPrefix(const AtomicString &_prefix, ExceptionCode& ec)
{
    ec = 0;
    checkSetPrefix(_prefix, ec);
    if (ec)
        return;

    m_tagName.setPrefix(_prefix);
}

KURL Element::baseURI() const
{
    KURL base(getAttribute(baseAttr));
    if (!base.protocol().isEmpty())
        return base;

    Node* parent = parentNode();
    if (!parent)
        return base;

    const KURL& parentBase = parent->baseURI();
    if (parentBase.isNull())
        return base;

    return KURL(parentBase, base.string());
}

void Element::createAttributeMap() const
{
    namedAttrMap = NamedAttrMap::create(const_cast<Element*>(this));
}

bool Element::isURLAttribute(Attribute*) const
{
    return false;
}

const QualifiedName& Element::imageSourceAttributeName() const
{
    return srcAttr;
}

RenderObject* Element::createRenderer(RenderArena* arena, RenderStyle* style)
{
    if (document()->documentElement() == this && style->display() == NONE) {
        // Ignore display: none on root elements.  Force a display of block in that case.
        RenderBlock* result = new (arena) RenderBlock(this);
        if (result)
            result->setAnimatableStyle(style);
        return result;
    }
    return RenderObject::createObject(this, style);
}


void Element::insertedIntoDocument()
{
    // need to do superclass processing first so inDocument() is true
    // by the time we reach updateId
    ContainerNode::insertedIntoDocument();

    if (hasID()) {
        if (NamedAttrMap* attrs = namedAttrMap.get()) {
            Attribute* idItem = attrs->getAttributeItem(idAttr);
            if (idItem && !idItem->isNull())
                updateId(nullAtom, idItem->value());
        }
    }
}

void Element::removedFromDocument()
{
    if (hasID()) {
        if (NamedAttrMap* attrs = namedAttrMap.get()) {
            Attribute* idItem = attrs->getAttributeItem(idAttr);
            if (idItem && !idItem->isNull())
                updateId(idItem->value(), nullAtom);
        }
    }

    ContainerNode::removedFromDocument();
}

void Element::attach()
{
    createRendererIfNeeded();
    ContainerNode::attach();
    if (hasRareData()) {   
        ElementRareData* data = rareData();
        if (data->needsFocusAppearanceUpdateSoonAfterAttach()) {
            if (isFocusable() && document()->focusedNode() == this)
                document()->updateFocusAppearanceSoon();
            data->setNeedsFocusAppearanceUpdateSoonAfterAttach(false);
        }
    }
}

void Element::detach()
{
    cancelFocusAppearanceUpdate();
    if (hasRareData())
        rareData()->resetComputedStyle();
    ContainerNode::detach();
}

void Element::recalcStyle(StyleChange change)
{
    RenderStyle* currentStyle = renderStyle();
    bool hasParentStyle = parentNode() ? parentNode()->renderStyle() : false;
    bool hasPositionalRules = changed() && currentStyle && currentStyle->childrenAffectedByPositionalRules();
    bool hasDirectAdjacentRules = currentStyle && currentStyle->childrenAffectedByDirectAdjacentRules();

#if ENABLE(SVG)
    if (!hasParentStyle && isShadowNode() && isSVGElement())
        hasParentStyle = true;
#endif

    if ((change > NoChange || changed())) {
        if (hasRareData())
            rareData()->resetComputedStyle();
    }
    if (hasParentStyle && (change >= Inherit || changed())) {
        RefPtr<RenderStyle> newStyle = document()->styleSelector()->styleForElement(this);
        StyleChange ch = diff(currentStyle, newStyle.get());
        if (ch == Detach || !currentStyle) {
            if (attached())
                detach();
            attach(); // FIXME: The style gets computed twice by calling attach. We could do better if we passed the style along.
            // attach recalulates the style for all children. No need to do it twice.
            setChanged(NoStyleChange);
            setHasChangedChild(false);
            return;
        }

        if (currentStyle) {
            // Preserve "affected by" bits that were propagated to us from descendants in the case where we didn't do a full
            // style change (e.g., only inline style changed).
            if (currentStyle->affectedByHoverRules())
                newStyle->setAffectedByHoverRules(true);
            if (currentStyle->affectedByActiveRules())
                newStyle->setAffectedByActiveRules(true);
            if (currentStyle->affectedByDragRules())
                newStyle->setAffectedByDragRules(true);
            if (currentStyle->childrenAffectedByForwardPositionalRules())
                newStyle->setChildrenAffectedByForwardPositionalRules();
            if (currentStyle->childrenAffectedByBackwardPositionalRules())
                newStyle->setChildrenAffectedByBackwardPositionalRules();
            if (currentStyle->childrenAffectedByFirstChildRules())
                newStyle->setChildrenAffectedByFirstChildRules();
            if (currentStyle->childrenAffectedByLastChildRules())
                newStyle->setChildrenAffectedByLastChildRules();
            if (currentStyle->childrenAffectedByDirectAdjacentRules())
                newStyle->setChildrenAffectedByDirectAdjacentRules();
        }

        if (ch != NoChange) {
            setRenderStyle(newStyle);
        } else if (changed() && (styleChangeType() != AnimationStyleChange) && (document()->usesSiblingRules() || document()->usesDescendantRules())) {
            // Although no change occurred, we use the new style so that the cousin style sharing code won't get
            // fooled into believing this style is the same.  This is only necessary if the document actually uses
            // sibling/descendant rules, since otherwise it isn't possible for ancestor styles to affect sharing of
            // descendants.
            if (renderer())
                renderer()->setStyleInternal(newStyle.get());
            else
                setRenderStyle(newStyle);
        } else if (styleChangeType() == AnimationStyleChange)
             setRenderStyle(newStyle);

        if (change != Force) {
            if ((document()->usesDescendantRules() || hasPositionalRules) && styleChangeType() >= FullStyleChange)
                change = Force;
            else
                change = ch;
        }
    }

    // FIXME: This check is good enough for :hover + foo, but it is not good enough for :hover + foo + bar.
    // For now we will just worry about the common case, since it's a lot trickier to get the second case right
    // without doing way too much re-resolution.
    bool forceCheckOfNextElementSibling = false;
    for (Node *n = firstChild(); n; n = n->nextSibling()) {
        bool childRulesChanged = n->changed() && n->styleChangeType() == FullStyleChange;
        if (forceCheckOfNextElementSibling && n->isElementNode())
            n->setChanged();
        if (change >= Inherit || n->isTextNode() || n->hasChangedChild() || n->changed())
            n->recalcStyle(change);
        if (n->isElementNode())
            forceCheckOfNextElementSibling = childRulesChanged && hasDirectAdjacentRules;
    }

    setChanged(NoStyleChange);
    setHasChangedChild(false);
}

bool Element::childTypeAllowed(NodeType type)
{
    switch (type) {
        case ELEMENT_NODE:
        case TEXT_NODE:
        case COMMENT_NODE:
        case PROCESSING_INSTRUCTION_NODE:
        case CDATA_SECTION_NODE:
        case ENTITY_REFERENCE_NODE:
            return true;
            break;
        default:
            return false;
    }
}

static void checkForSiblingStyleChanges(Element* e, RenderStyle* style, bool finishedParsingCallback,
                                        Node* beforeChange, Node* afterChange, int childCountDelta)
{
    if (!style || (e->changed() && style->childrenAffectedByPositionalRules()))
        return;

    // :first-child.  In the parser callback case, we don't have to check anything, since we were right the first time.
    // In the DOM case, we only need to do something if |afterChange| is not 0.
    // |afterChange| is 0 in the parser case, so it works out that we'll skip this block.
    if (style->childrenAffectedByFirstChildRules() && afterChange) {
        // Find our new first child.
        Node* newFirstChild = 0;
        for (newFirstChild = e->firstChild(); newFirstChild && !newFirstChild->isElementNode(); newFirstChild = newFirstChild->nextSibling()) {};
        
        // Find the first element node following |afterChange|
        Node* firstElementAfterInsertion = 0;
        for (firstElementAfterInsertion = afterChange;
             firstElementAfterInsertion && !firstElementAfterInsertion->isElementNode();
             firstElementAfterInsertion = firstElementAfterInsertion->nextSibling()) {};
        
        // This is the insert/append case.
        if (newFirstChild != firstElementAfterInsertion && firstElementAfterInsertion && firstElementAfterInsertion->attached() &&
            firstElementAfterInsertion->renderStyle() && firstElementAfterInsertion->renderStyle()->firstChildState())
            firstElementAfterInsertion->setChanged();
            
        // We also have to handle node removal.
        if (childCountDelta < 0 && newFirstChild == firstElementAfterInsertion && newFirstChild && newFirstChild->renderStyle() && !newFirstChild->renderStyle()->firstChildState())
            newFirstChild->setChanged();
    }

    // :last-child.  In the parser callback case, we don't have to check anything, since we were right the first time.
    // In the DOM case, we only need to do something if |afterChange| is not 0.
    if (style->childrenAffectedByLastChildRules() && beforeChange) {
        // Find our new last child.
        Node* newLastChild = 0;
        for (newLastChild = e->lastChild(); newLastChild && !newLastChild->isElementNode(); newLastChild = newLastChild->previousSibling()) {};
        
        // Find the last element node going backwards from |beforeChange|
        Node* lastElementBeforeInsertion = 0;
        for (lastElementBeforeInsertion = beforeChange;
             lastElementBeforeInsertion && !lastElementBeforeInsertion->isElementNode();
             lastElementBeforeInsertion = lastElementBeforeInsertion->previousSibling()) {};
        
        if (newLastChild != lastElementBeforeInsertion && lastElementBeforeInsertion && lastElementBeforeInsertion->attached() &&