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 RenderMathMLRoot::updateStyle()
{
// We try and read constants to draw the radical from the OpenType MATH and use fallback values otherwise.
const auto& primaryFont = style().fontCascade().primaryFont();
if (auto* mathData = style().fontCascade().primaryFont().mathData()) {
m_ruleThickness = mathData->getMathConstant(primaryFont, OpenTypeMathData::RadicalRuleThickness);
m_verticalGap = mathData->getMathConstant(primaryFont, mathMLStyle()->displayStyle() ? OpenTypeMathData::RadicalDisplayStyleVerticalGap : OpenTypeMathData::RadicalVerticalGap);
m_extraAscender = mathData->getMathConstant(primaryFont, OpenTypeMathData::RadicalExtraAscender);
if (m_kind == RootWithIndex) {
m_kernBeforeDegree = mathData->getMathConstant(primaryFont, OpenTypeMathData::RadicalKernBeforeDegree);
m_kernAfterDegree = mathData->getMathConstant(primaryFont, OpenTypeMathData::RadicalKernAfterDegree);
m_degreeBottomRaisePercent = mathData->getMathConstant(primaryFont, OpenTypeMathData::RadicalDegreeBottomRaisePercent);
}
} else {
// RadicalVerticalGap: Suggested value is 5/4 default rule thickness.
// RadicalDisplayStyleVerticalGap: Suggested value is default rule thickness + 1/4 x-height.
// RadicalRuleThickness: Suggested value is default rule thickness.
// RadicalExtraAscender: Suggested value is RadicalRuleThickness.
// RadicalKernBeforeDegree: No suggested value provided. OT Math Illuminated mentions 5/18 em, Gecko uses 0.
// RadicalKernAfterDegree: Suggested value is -10/18 of em.
// RadicalDegreeBottomRaisePercent: Suggested value is 60%.
m_ruleThickness = ruleThicknessFallback();
if (mathMLStyle()->displayStyle())
m_verticalGap = m_ruleThickness + style().fontMetrics().xHeight() / 4;
else
m_verticalGap = 5 * m_ruleThickness / 4;
if (m_kind == RootWithIndex) {
m_extraAscender = m_ruleThickness;
m_kernBeforeDegree = 5 * style().fontCascade().size() / 18;
m_kernAfterDegree = -10 * style().fontCascade().size() / 18;
m_degreeBottomRaisePercent = 0.6f;
}
}
}
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;
}
}
