bool Text::textLayoutObjectIsNeeded(const ComputedStyle& style, const LayoutObject& parent)
{
if (!parent.canHaveChildren())
return false;
if (isEditingText())
return true;
if (!length())
return false;
if (style.display() == NONE)
return false;
if (!containsOnlyWhitespace())
return true;
if (!canHaveWhitespaceChildren(parent, this))
return false;
// pre-wrap in SVG never makes layoutObject.
if (style.whiteSpace() == PRE_WRAP && parent.isSVG())
return false;
// pre/pre-wrap/-bb-pre-wrap-text/pre-line always make layoutObjects.
if (style.preserveNewline())
return true;
// childNeedsDistributionRecalc() here is rare, only happens JS calling surroundContents() etc. from DOMNodeInsertedIntoDocument etc.
if (document().childNeedsDistributionRecalc())
return true;
const LayoutObject* prev = LayoutTreeBuilderTraversal::previousSiblingLayoutObject(*this);
if (prev && prev->isBR()) // <span><br/> <br/></span>
return false;
if (parent.isLayoutInline()) {
// <span><div/> <div/></span>
if (prev && !prev->isInline() && !prev->isOutOfFlowPositioned())
return false;
} else {
if (parent.isLayoutBlock() && !parent.childrenInline() && (!prev || !prev->isInline()))
return false;
// Avoiding creation of a layoutObject for the text node is a non-essential memory optimization.
// So to avoid blowing up on very wide DOMs, we limit the number of siblings to visit.
unsigned maxSiblingsToVisit = 50;
LayoutObject* first = parent.slowFirstChild();
while (first && first->isFloatingOrOutOfFlowPositioned() && maxSiblingsToVisit--)
first = first->nextSibling();
if (!first || first == layoutObject() || LayoutTreeBuilderTraversal::nextSiblingLayoutObject(*this) == first) {
// Whitespace at the start of a block just goes away. Don't even
// make a layout object for this text.
return false;
}
}
return true;
}
bool LayoutTreeBuilderForElement::shouldCreateLayoutObject() const
{
if (!m_layoutObjectParent)
return false;
// FIXME: Should the following be in SVGElement::layoutObjectIsNeeded()?
if (m_node->isSVGElement()) {
// SVG elements only render when inside <svg>, or if the element is an <svg> itself.
if (!isSVGSVGElement(*m_node) && (!m_layoutObjectParent->node() || !m_layoutObjectParent->node()->isSVGElement()))
return false;
if (!toSVGElement(m_node)->isValid())
return false;
}
LayoutObject* parentLayoutObject = this->parentLayoutObject();
if (!parentLayoutObject)
return false;
if (!parentLayoutObject->canHaveChildren())
return false;
return m_node->layoutObjectIsNeeded(style());
}
