C++ ShadowRoot::firstChild方法代码示例

void SVGUseElement::buildShadowAndInstanceTree(SVGElement* target)
{
    ASSERT(!m_targetElementInstance);
    ASSERT(!m_needsShadowTreeRecreation);

    // <use> creates a "user agent" shadow root. Do not build the shadow/instance tree for <use>
    // elements living in a user agent shadow tree because they will get expanded in a second
    // pass -- see expandUseElementsInShadowTree().
    if (inUseShadowTree())
        return;

    // Do not allow self-referencing.
    // 'target' may be null, if it's a non SVG namespaced element.
    if (!target || target == this || isDisallowedElement(target))
        return;

    // Set up root SVG element in shadow tree.
    RefPtrWillBeRawPtr<Element> newChild = target->cloneElementWithoutChildren();
    m_targetElementInstance = toSVGElement(newChild.get());
    ShadowRoot* shadowTreeRootElement = userAgentShadowRoot();
    shadowTreeRootElement->appendChild(newChild.release());

    // Clone the target subtree into the shadow tree, not handling <use> and <symbol> yet.

    // SVG specification does not say a word about <use> & cycles. My view on this is: just ignore it!
    // Non-appearing <use> content is easier to debug, then half-appearing content.
    if (!buildShadowTree(target, m_targetElementInstance.get(), false)) {
        clearShadowTree();
        return;
    }

    if (instanceTreeIsLoading(m_targetElementInstance.get()))
        return;

    // Assure shadow tree building was successfull
    ASSERT(m_targetElementInstance);
    ASSERT(m_targetElementInstance->correspondingUseElement() == this);
    ASSERT(m_targetElementInstance->correspondingElement() == target);

    // Expand all <use> elements in the shadow tree.
    // Expand means: replace the actual <use> element by what it references.
    if (!expandUseElementsInShadowTree(m_targetElementInstance.get())) {
        clearShadowTree();
        return;
    }

    // Expand all <symbol> elements in the shadow tree.
    // Expand means: replace the actual <symbol> element by the <svg> element.
    expandSymbolElementsInShadowTree(toSVGElement(shadowTreeRootElement->firstChild()));

    m_targetElementInstance = toSVGElement(shadowTreeRootElement->firstChild());
    transferUseWidthAndHeightIfNeeded(*this, m_targetElementInstance.get(), *m_targetElementInstance->correspondingElement());

    ASSERT(m_targetElementInstance->parentNode() == shadowTreeRootElement);

    // Update relative length information.
    updateRelativeLengthsInformation();
}

void SVGTRefElement::updateReferencedText()
{
    String textContent;
    if (Element* target = SVGURIReference::targetElementFromIRIString(href(), document()))
        textContent = target->textContent();

    ASSERT(shadow());
    ShadowRoot* root = shadow()->oldestShadowRoot();
    if (!root->firstChild())
        root->appendChild(SVGShadowText::create(document(), textContent), ASSERT_NO_EXCEPTION);
    else
        root->firstChild()->setTextContent(textContent, ASSERT_NO_EXCEPTION);
}

void SVGTRefElement::updateReferencedText(Element* target)
{
    String textContent;
    if (target)
        textContent = target->textContent();

    ASSERT(shadowRoot());
    ShadowRoot* root = shadowRoot();
    if (!root->firstChild())
        root->appendChild(Text::create(document(), textContent), ASSERT_NO_EXCEPTION);
    else {
        ASSERT(root->firstChild()->isTextNode());
        root->firstChild()->setTextContent(textContent, ASSERT_NO_EXCEPTION);
    }
}

void ShadowTree::recalcShadowTreeStyle(Node::StyleChange change)
{
    ShadowRoot* youngest = youngestShadowRoot();
    if (!youngest)
        return;

    if (needsReattachHostChildrenAndShadow())
        reattachHostChildrenAndShadow();
    else {
        StyleResolver* styleResolver = youngest->document()->styleResolver();

        styleResolver->pushParentShadowRoot(youngest);
        for (Node* n = youngest->firstChild(); n; n = n->nextSibling()) {
            if (n->isElementNode())
                static_cast<Element*>(n)->recalcStyle(change);
            else if (n->isTextNode())
                toText(n)->recalcTextStyle(change);
        }
        styleResolver->popParentShadowRoot(youngest);
    }

    clearNeedsReattachHostChildrenAndShadow();
    for (ShadowRoot* root = youngestShadowRoot(); root; root = root->olderShadowRoot()) {
        root->clearNeedsStyleRecalc();
        root->clearChildNeedsStyleRecalc();
    }
}

static inline void getDecorationRootAndDecoratedRoot(HTMLInputElement* input, ShadowRoot*& decorationRoot, ShadowRoot*& decoratedRoot)
{
    ShadowRoot* existingRoot = input->youngestShadowRoot();
    ShadowRoot* newRoot = 0;
    while (existingRoot->childNodeCount() == 1 && existingRoot->firstChild()->hasTagName(shadowTag)) {
        newRoot = existingRoot;
        existingRoot = existingRoot->olderShadowRoot();
        ASSERT(existingRoot);
    }
    if (newRoot)
        newRoot->removeChild(newRoot->firstChild());
    else
        newRoot = ShadowRoot::create(input, ShadowRoot::UserAgentShadowRoot, ASSERT_NO_EXCEPTION).get();
    decorationRoot = newRoot;
    decoratedRoot = existingRoot;
}

SliderThumbElement* sliderThumbElementOf(Node* node)
{
    ASSERT(node);
    ShadowRoot* shadow = node->toInputElement()->shadowTree()->oldestShadowRoot();
    ASSERT(shadow);
    Node* thumb = shadow->firstChild()->firstChild()->firstChild();
    ASSERT(thumb);
    return toSliderThumbElement(thumb);
}

void HTMLPlugInImageElement::updateSnapshotInfo()
{
    ShadowRoot* root = userAgentShadowRoot();
    if (!root)
        return;

    Element* shadowContainer = toElement(root->firstChild());
    shadowContainer->setAttribute(classAttr, classNameForShadowRoot(this, m_isPrimarySnapshottedPlugIn));
}

HTMLElement* sliderTrackElementOf(Node* node)
{
    RELEASE_ASSERT(node->hasTagName(inputTag));
    ShadowRoot* shadow = toHTMLInputElement(node)->userAgentShadowRoot();
    ASSERT(shadow);
    Node* track = shadow->firstChild()->firstChild();
    ASSERT(track);
    return toHTMLElement(track);
}

TrackLimiterElement* trackLimiterElementOf(Node* node)
{
    ASSERT(node);
    ShadowRoot* shadow = node->toInputElement()->shadowRoot();
    ASSERT(shadow);
    Node* limiter = shadow->firstChild()->lastChild();
    ASSERT(limiter);
    return static_cast<TrackLimiterElement*>(limiter);
}

HTMLElement* sliderTrackElementOf(Node* node)
{
    ASSERT(node);
    ShadowRoot* shadow = node->toInputElement()->userAgentShadowRoot();
    ASSERT(shadow);
    Node* track = shadow->firstChild()->firstChild();
    ASSERT(track);
    return toHTMLElement(track);
}

static inline void getDecorationRootAndDecoratedRoot(HTMLInputElement* input, ShadowRoot*& decorationRoot, ShadowRoot*& decoratedRoot)
{
    ShadowRoot* existingRoot = input->youngestShadowRoot();
    ShadowRoot* newRoot = 0;
    while (existingRoot->childNodeCount() == 1 && existingRoot->firstChild()->hasTagName(shadowTag)) {
        newRoot = existingRoot;
        existingRoot = existingRoot->olderShadowRoot();
        ASSERT(existingRoot);
    }
    if (newRoot)
        newRoot->removeChild(newRoot->firstChild());
    else {
        // FIXME: This interacts really badly with author shadow roots because now
        // we can interleave user agent and author shadow roots on the element meaning
        // input.shadowRoot may be inaccessible if the browser has decided to decorate
        // the input.
        newRoot = input->ensureShadow()->addShadowRoot(input, ShadowRoot::UserAgentShadowRoot);
    }
    decorationRoot = newRoot;
    decoratedRoot = existingRoot;
}

void HTMLPlugInImageElement::checkSnapshotStatus()
{
    if (!renderer()->isSnapshottedPlugIn()) {
        if (displayState() == Playing)
            checkSizeChangeForSnapshotting();
        return;
    }

    ShadowRoot* root = userAgentShadowRoot();
    if (!root)
        return;

    Element* shadowContainer = toElement(root->firstChild());
    shadowContainer->setAttribute(classAttr, classNameForShadowRoot(this));
}

void HTMLImageElement::destroyImageControls()
{
    ShadowRoot* shadowRoot = userAgentShadowRoot();
    if (!shadowRoot)
        return;

    if (Node* node = shadowRoot->firstChild()) {
        ASSERT_WITH_SECURITY_IMPLICATION(node->isImageControlsRootElement());
        shadowRoot->removeChild(*node);
    }

    auto* renderObject = renderer();
    if (!renderObject)
        return;

    downcast<RenderImage>(*renderObject).setHasShadowControls(false);
}

void TextFieldDecorationElement::decorate(HTMLInputElement* input, bool visible)
{
    ASSERT(input);
    ShadowRoot* existingRoot;
    ShadowRoot* decorationRoot;
    getDecorationRootAndDecoratedRoot(input, decorationRoot, existingRoot);
    ASSERT(decorationRoot);
    ASSERT(existingRoot);
    RefPtr<HTMLDivElement> box = HTMLDivElement::create(input->document());
    decorationRoot->appendChild(box);
    box->setInlineStyleProperty(CSSPropertyDisplay, CSSValueWebkitBox);
    box->setInlineStyleProperty(CSSPropertyWebkitBoxAlign, CSSValueCenter);
    ASSERT(existingRoot->childNodeCount() == 1);
    toHTMLElement(existingRoot->firstChild())->setInlineStyleProperty(CSSPropertyWebkitBoxFlex, 1.0, CSSPrimitiveValue::CSS_NUMBER);
    box->appendChild(HTMLShadowElement::create(HTMLNames::shadowTag, input->document()));

    setInlineStyleProperty(CSSPropertyDisplay, visible ? CSSValueBlock : CSSValueNone);
    box->appendChild(this);
}

bool RuleFeatureSet::invalidateStyleForClassChangeOnChildren(Element* element, Vector<AtomicString>& invalidationClasses, bool foundInvalidationSet)
{
    bool someChildrenNeedStyleRecalc = false;
    for (ShadowRoot* root = element->youngestShadowRoot(); root; root = root->olderShadowRoot()) {
        for (Node* child = root->firstChild(); child; child = child->nextSibling()) {
            if (child->isElementNode()) {
                Element* childElement = toElement(child);
                bool childRecalced = invalidateStyleForClassChange(childElement, invalidationClasses, foundInvalidationSet);
                someChildrenNeedStyleRecalc = someChildrenNeedStyleRecalc || childRecalced;
            }
        }
    }
    for (Node* child = element->firstChild(); child; child = child->nextSibling()) {
        if (child->isElementNode()) {
            Element* childElement = toElement(child);
            bool childRecalced = invalidateStyleForClassChange(childElement, invalidationClasses, foundInvalidationSet);
            someChildrenNeedStyleRecalc = someChildrenNeedStyleRecalc || childRecalced;
        }
    }
    return someChildrenNeedStyleRecalc;
}