int RenderMathMLUnderOver::firstLineBaseline() const
{
RenderBox* base = firstChildBox();
if (!base)
return -1;
LayoutUnit baseline = base->firstLineBaseline();
if (baseline != -1)
baseline += base->logicalTop();
return baseline;
}
Optional<int> RenderMathMLUnderOver::firstLineBaseline() const
{
RenderBox* base = firstChildBox();
if (!base)
return Optional<int>();
Optional<int> baseline = base->firstLineBaseline();
if (baseline)
baseline.value() += static_cast<int>(base->logicalTop());
return baseline;
}
void RenderMathMLScripts::layout()
{
RenderMathMLBlock::layout();
if (!m_baseWrapper)
return;
RenderBox* base = m_baseWrapper->firstChildBox();
if (!base)
return;
// Our layout rules include: Don't let the superscript go below the "axis" (half x-height above the
// baseline), or the subscript above the axis. Also, don't let the superscript's top edge be
// below the base's top edge, or the subscript's bottom edge above the base's bottom edge.
LayoutUnit baseHeight = base->logicalHeight();
LayoutUnit baseBaseline = base->firstLineBaseline().valueOr(baseHeight);
LayoutUnit axis = style().fontMetrics().xHeight() / 2;
int fontSize = style().fontSize();
ASSERT(m_baseWrapper->style().hasOneRef());
bool needsSecondLayout = false;
LayoutUnit topPadding = 0;
LayoutUnit bottomPadding = 0;
Element* scriptElement = element();
LayoutUnit superscriptShiftValue = 0;
LayoutUnit subscriptShiftValue = 0;
if (m_kind == Sub || m_kind == SubSup || m_kind == Multiscripts)
parseMathMLLength(scriptElement->fastGetAttribute(MathMLNames::subscriptshiftAttr), subscriptShiftValue, &style(), false);
if (m_kind == Super || m_kind == SubSup || m_kind == Multiscripts)
parseMathMLLength(scriptElement->fastGetAttribute(MathMLNames::superscriptshiftAttr), superscriptShiftValue, &style(), false);
bool isPostScript = true;
RenderMathMLBlock* subSupPair = downcast<RenderMathMLBlock>(m_baseWrapper->nextSibling());
for (; subSupPair; subSupPair = downcast<RenderMathMLBlock>(subSupPair->nextSibling())) {
// We skip the base and <mprescripts/> elements.
if (isPrescript(*subSupPair)) {
if (!isPostScript)
break;
isPostScript = false;
continue;
}
if (RenderBox* superscript = m_kind == Sub ? 0 : subSupPair->lastChildBox()) {
LayoutUnit superscriptHeight = superscript->logicalHeight();
LayoutUnit superscriptBaseline = superscript->firstLineBaseline().valueOr(superscriptHeight);
LayoutUnit minBaseline = std::max<LayoutUnit>(fontSize / 3 + 1 + superscriptBaseline, superscriptHeight + axis + superscriptShiftValue);
topPadding = std::max<LayoutUnit>(topPadding, minBaseline - baseBaseline);
}
if (RenderBox* subscript = m_kind == Super ? 0 : subSupPair->firstChildBox()) {
LayoutUnit subscriptHeight = subscript->logicalHeight();
LayoutUnit subscriptBaseline = subscript->firstLineBaseline().valueOr(subscriptHeight);
LayoutUnit baseExtendUnderBaseline = baseHeight - baseBaseline;
LayoutUnit subscriptUnderItsBaseline = subscriptHeight - subscriptBaseline;
LayoutUnit minExtendUnderBaseline = std::max<LayoutUnit>(fontSize / 5 + 1 + subscriptUnderItsBaseline, subscriptHeight + subscriptShiftValue - axis);
bottomPadding = std::max<LayoutUnit>(bottomPadding, minExtendUnderBaseline - baseExtendUnderBaseline);
}
}
Length newPadding(topPadding, Fixed);
if (newPadding != m_baseWrapper->style().paddingTop()) {
m_baseWrapper->style().setPaddingTop(newPadding);
needsSecondLayout = true;
}
newPadding = Length(bottomPadding, Fixed);
if (newPadding != m_baseWrapper->style().paddingBottom()) {
m_baseWrapper->style().setPaddingBottom(newPadding);
needsSecondLayout = true;
}
if (!needsSecondLayout)
return;
setNeedsLayout(MarkOnlyThis);
m_baseWrapper->setChildNeedsLayout(MarkOnlyThis);
RenderMathMLBlock::layout();
}
