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();
}
bool SVGUseElement::instanceTreeIsLoading(SVGElementInstance* targetElementInstance)
{
for (SVGElementInstance* instance = targetElementInstance->firstChild(); instance; instance = instance->nextSibling()) {
if (SVGUseElement* use = instance->correspondingUseElement()) {
if (use->cachedDocumentIsStillLoading())
return true;
}
if (instance->hasChildNodes())
instanceTreeIsLoading(instance);
}
return false;
}
void SVGUseElement::buildShadowAndInstanceTree(SVGElement* target)
{
ASSERT(!m_targetElementInstance);
// Do not build the shadow/instance tree for <use> elements living in a shadow tree.
// The will be expanded soon anyway - see expandUseElementsInShadowTree().
if (isInShadowTree())
return;
// Do not allow self-referencing.
// 'target' may be null, if it's a non SVG namespaced element.
if (!target || target == this)
return;
// Why a seperated instance/shadow tree? SVG demands it:
// The instance tree is accesable from JavaScript, and has to
// expose a 1:1 copy of the referenced tree, whereas internally we need
// to alter the tree for correct "use-on-symbol", "use-on-svg" support.
// Build instance tree. Create root SVGElementInstance object for the first sub-tree node.
//
// Spec: If the 'use' element references a simple graphics element such as a 'rect', then there is only a
// single SVGElementInstance object, and the correspondingElement attribute on this SVGElementInstance object
// is the SVGRectElement that corresponds to the referenced 'rect' element.
m_targetElementInstance = SVGElementInstance::create(this, this, target);
// Eventually enter recursion to build SVGElementInstance objects for the sub-tree children
bool foundProblem = false;
buildInstanceTree(target, m_targetElementInstance.get(), foundProblem, false);
if (instanceTreeIsLoading(m_targetElementInstance.get()))
return;
// 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 (foundProblem) {
clearResourceReferences();
return;
}
// Assure instance tree building was successfull
ASSERT(m_targetElementInstance);
ASSERT(!m_targetElementInstance->shadowTreeElement());
ASSERT(m_targetElementInstance->correspondingUseElement() == this);
ASSERT(m_targetElementInstance->directUseElement() == this);
ASSERT(m_targetElementInstance->correspondingElement() == target);
ShadowRoot* shadowTreeRootElement = shadowRoot();
ASSERT(shadowTreeRootElement);
// Build shadow tree from instance tree
// This also handles the special cases: <use> on <symbol>, <use> on <svg>.
buildShadowTree(target, m_targetElementInstance.get());
// Expand all <use> elements in the shadow tree.
// Expand means: replace the actual <use> element by what it references.
expandUseElementsInShadowTree(shadowTreeRootElement);
// Expand all <symbol> elements in the shadow tree.
// Expand means: replace the actual <symbol> element by the <svg> element.
expandSymbolElementsInShadowTree(shadowTreeRootElement);
// Now that the shadow tree is completly expanded, we can associate
// shadow tree elements <-> instances in the instance tree.
associateInstancesWithShadowTreeElements(shadowTreeRootElement->firstChild(), m_targetElementInstance.get());
// If no shadow tree element is present, this means that the reference root
// element was removed, as it is disallowed (ie. <use> on <foreignObject>)
// Do NOT leave an inconsistent instance tree around, instead destruct it.
if (!m_targetElementInstance->shadowTreeElement()) {
clearResourceReferences();
return;
}
ASSERT(m_targetElementInstance->shadowTreeElement()->parentNode() == shadowTreeRootElement);
// Transfer event listeners assigned to the referenced element to our shadow tree elements.
transferEventListenersToShadowTree(m_targetElementInstance.get());
// Update relative length information.
updateRelativeLengthsInformation();
// Eventually dump instance tree
#ifdef DUMP_INSTANCE_TREE
String text;
unsigned int depth = 0;
dumpInstanceTree(depth, text, m_targetElementInstance.get());
fprintf(stderr, "\nDumping <use> instance tree:\n%s\n", text.latin1().data());
#endif
// Eventually dump shadow tree
#ifdef DUMP_SHADOW_TREE
RefPtr<XMLSerializer> serializer = XMLSerializer::create();
String markup = serializer->serializeToString(shadowTreeRootElement, ASSERT_NO_EXCEPTION);
fprintf(stderr, "Dumping <use> shadow tree markup:\n%s\n", markup.latin1().data());
#endif
}
