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()); }