RenderMathMLFraction::FractionParameters RenderMathMLFraction::fractionParameters()
{
ASSERT(!isStack());
FractionParameters parameters;
// We try and read constants to draw the fraction from the OpenType MATH and use fallback values otherwise.
const auto& primaryFont = style().fontCascade().primaryFont();
const auto* mathData = style().fontCascade().primaryFont().mathData();
bool display = mathMLStyle()->displayStyle();
if (mathData) {
parameters.numeratorGapMin = mathData->getMathConstant(primaryFont, display ? OpenTypeMathData::FractionNumDisplayStyleGapMin : OpenTypeMathData::FractionNumeratorGapMin);
parameters.denominatorGapMin = mathData->getMathConstant(primaryFont, display ? OpenTypeMathData::FractionDenomDisplayStyleGapMin : OpenTypeMathData::FractionDenominatorGapMin);
parameters.numeratorMinShiftUp = mathData->getMathConstant(primaryFont, display ? OpenTypeMathData::FractionNumeratorDisplayStyleShiftUp : OpenTypeMathData::FractionNumeratorShiftUp);
parameters.denominatorMinShiftDown = mathData->getMathConstant(primaryFont, display ? OpenTypeMathData::FractionDenominatorDisplayStyleShiftDown : OpenTypeMathData::FractionDenominatorShiftDown);
} else {
// The MATH table specification suggests default rule thickness or (in displaystyle) 3 times default rule thickness for the gaps.
parameters.numeratorGapMin = display ? 3 * ruleThicknessFallback() : ruleThicknessFallback();
parameters.denominatorGapMin = parameters.numeratorGapMin;
// The MATH table specification does not suggest any values for shifts, so we leave them at zero.
parameters.numeratorMinShiftUp = 0;
parameters.denominatorMinShiftDown = 0;
}
return parameters;
}
void RenderMathMLFraction::layoutBlock(bool relayoutChildren, LayoutUnit)
{
ASSERT(needsLayout());
if (!relayoutChildren && simplifiedLayout())
return;
if (!isValid()) {
setLogicalWidth(0);
setLogicalHeight(0);
clearNeedsLayout();
return;
}
numerator().layoutIfNeeded();
denominator().layoutIfNeeded();
setLogicalWidth(std::max(numerator().logicalWidth(), denominator().logicalWidth()));
updateLineThickness();
LayoutUnit verticalOffset = 0; // This is the top of the renderer.
LayoutPoint numeratorLocation(horizontalOffset(numerator(), element().numeratorAlignment()), verticalOffset);
numerator().setLocation(numeratorLocation);
LayoutUnit numeratorAscent = ascentForChild(numerator());
LayoutUnit numeratorDescent = numerator().logicalHeight() - numeratorAscent;
LayoutUnit denominatorAscent = ascentForChild(denominator());
LayoutUnit denominatorDescent = denominator().logicalHeight() - denominatorAscent;
if (isStack()) {
LayoutUnit gapMin, topShiftUp, bottomShiftDown;
getStackParameters(gapMin, topShiftUp, bottomShiftDown);
LayoutUnit gap = topShiftUp - numeratorDescent + bottomShiftDown - denominatorAscent;
if (gap < gapMin) {
// If the gap is not large enough, we increase the shifts by the same value.
LayoutUnit delta = (gapMin - gap) / 2;
topShiftUp += delta;
bottomShiftDown += delta;
}
verticalOffset += numeratorAscent + topShiftUp; // This is the middle of the stack gap.
m_ascent = verticalOffset + mathAxisHeight();
verticalOffset += bottomShiftDown - denominatorAscent;
} else {
LayoutUnit numeratorGapMin, denominatorGapMin, numeratorMinShiftUp, denominatorMinShiftDown;
getFractionParameters(numeratorGapMin, denominatorGapMin, numeratorMinShiftUp, denominatorMinShiftDown);
verticalOffset += std::max(numerator().logicalHeight() + numeratorGapMin + m_lineThickness / 2, numeratorAscent + numeratorMinShiftUp); // This is the middle of the fraction bar.
m_ascent = verticalOffset + mathAxisHeight();
verticalOffset += std::max(m_lineThickness / 2 + denominatorGapMin, denominatorMinShiftDown - denominatorAscent);
}
LayoutPoint denominatorLocation(horizontalOffset(denominator(), element().denominatorAlignment()), verticalOffset);
denominator().setLocation(denominatorLocation);
verticalOffset = std::max(verticalOffset + denominator().logicalHeight(), m_ascent + denominatorDescent); // This is the bottom of our renderer.
setLogicalHeight(verticalOffset);
clearNeedsLayout();
}
void RenderMathMLFraction::getStackParameters(LayoutUnit& gapMin, LayoutUnit& topShiftUp, LayoutUnit& bottomShiftDown)
{
ASSERT(isStack());
// We try and read constants to draw the stack from the OpenType MATH and use fallback values otherwise.
const auto& primaryFont = style().fontCascade().primaryFont();
const auto* mathData = style().fontCascade().primaryFont().mathData();
bool display = mathMLStyle()->displayStyle();
if (mathData) {
gapMin = mathData->getMathConstant(primaryFont, display ? OpenTypeMathData::StackDisplayStyleGapMin : OpenTypeMathData::StackGapMin);
topShiftUp = mathData->getMathConstant(primaryFont, display ? OpenTypeMathData::StackTopDisplayStyleShiftUp : OpenTypeMathData::StackTopShiftUp);
bottomShiftDown = mathData->getMathConstant(primaryFont, display ? OpenTypeMathData::StackBottomDisplayStyleShiftDown : OpenTypeMathData::StackBottomShiftDown);
} else {
// We use the values suggested in the MATH table specification.
gapMin = display ? 7 * ruleThicknessFallback() : 3 * ruleThicknessFallback();
// The MATH table specification does not suggest any values for shifts, so we leave them at zero.
topShiftUp = 0;
bottomShiftDown = 0;
}
}
void RenderMathMLFraction::paint(PaintInfo& info, const LayoutPoint& paintOffset)
{
RenderMathMLBlock::paint(info, paintOffset);
if (info.context().paintingDisabled() || info.phase != PaintPhaseForeground || style().visibility() != VISIBLE || !isValid() || isStack())
return;
IntPoint adjustedPaintOffset = roundedIntPoint(paintOffset + location() + LayoutPoint(0, m_ascent - mathAxisHeight()));
GraphicsContextStateSaver stateSaver(info.context());
info.context().setStrokeThickness(m_lineThickness);
info.context().setStrokeStyle(SolidStroke);
info.context().setStrokeColor(style().visitedDependentColor(CSSPropertyColor));
info.context().drawLine(adjustedPaintOffset, roundedIntPoint(LayoutPoint(adjustedPaintOffset.x() + logicalWidth(), adjustedPaintOffset.y())));
}
