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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
#include "nsMathMLmfracFrame.h"
#include "gfxUtils.h"
#include "mozilla/gfx/2D.h"
#include "mozilla/PresShell.h"
#include "mozilla/RefPtr.h"
#include "mozilla/StaticPrefs_mathml.h"
#include "nsLayoutUtils.h"
#include "nsPresContext.h"
#include "nsDisplayList.h"
#include "gfxContext.h"
#include "mozilla/dom/Document.h"
#include "mozilla/dom/MathMLElement.h"
#include <algorithm>
#include "gfxMathTable.h"
#include "gfxTextRun.h"
using namespace mozilla;
using namespace mozilla::gfx;
//
// <mfrac> -- form a fraction from two subexpressions - implementation
//
nsIFrame* NS_NewMathMLmfracFrame(PresShell* aPresShell, ComputedStyle* aStyle) {
return new (aPresShell)
nsMathMLmfracFrame(aStyle, aPresShell->GetPresContext());
}
NS_IMPL_FRAMEARENA_HELPERS(nsMathMLmfracFrame)
nsMathMLmfracFrame::~nsMathMLmfracFrame() = default;
eMathMLFrameType nsMathMLmfracFrame::GetMathMLFrameType() {
// frac is "inner" in TeXBook, Appendix G, rule 15e. See also page 170.
return eMathMLFrameType_Inner;
}
uint8_t nsMathMLmfracFrame::ScriptIncrement(nsIFrame* aFrame) {
if (StyleFont()->mMathStyle == StyleMathStyle::Compact && aFrame &&
(mFrames.FirstChild() == aFrame || mFrames.LastChild() == aFrame)) {
return 1;
}
return 0;
}
NS_IMETHODIMP
nsMathMLmfracFrame::TransmitAutomaticData() {
// The TeXbook (Ch 17. p.141) says the numerator inherits the compression
// while the denominator is compressed
UpdatePresentationDataFromChildAt(1, 1, NS_MATHML_COMPRESSED,
NS_MATHML_COMPRESSED);
// If displaystyle is false, then scriptlevel is incremented, so notify the
// children of this.
if (StyleFont()->mMathStyle == StyleMathStyle::Compact) {
PropagateFrameFlagFor(mFrames.FirstChild(),
NS_FRAME_MATHML_SCRIPT_DESCENDANT);
PropagateFrameFlagFor(mFrames.LastChild(),
NS_FRAME_MATHML_SCRIPT_DESCENDANT);
}
// if our numerator is an embellished operator, let its state bubble to us
GetEmbellishDataFrom(mFrames.FirstChild(), mEmbellishData);
if (NS_MATHML_IS_EMBELLISH_OPERATOR(mEmbellishData.flags)) {
// even when embellished, we need to record that <mfrac> won't fire
// Stretch() on its embellished child
mEmbellishData.direction = NS_STRETCH_DIRECTION_UNSUPPORTED;
}
return NS_OK;
}
nscoord nsMathMLmfracFrame::CalcLineThickness(nsPresContext* aPresContext,
ComputedStyle* aComputedStyle,
nsString& aThicknessAttribute,
nscoord onePixel,
nscoord aDefaultRuleThickness,
float aFontSizeInflation) {
nscoord defaultThickness = aDefaultRuleThickness;
nscoord lineThickness = aDefaultRuleThickness;
nscoord minimumThickness = onePixel;
// linethickness
if (!aThicknessAttribute.IsEmpty()) {
lineThickness = defaultThickness;
ParseNumericValue(aThicknessAttribute, &lineThickness,
dom::MathMLElement::PARSE_ALLOW_NEGATIVE, aPresContext,
aComputedStyle, aFontSizeInflation);
// MathML Core says a negative value is interpreted as 0.
if (lineThickness < 0) {
lineThickness = 0;
}
}
// use minimum if the lineThickness is a non-zero value less than minimun
if (lineThickness && lineThickness < minimumThickness)
lineThickness = minimumThickness;
return lineThickness;
}
void nsMathMLmfracFrame::BuildDisplayList(nsDisplayListBuilder* aBuilder,
const nsDisplayListSet& aLists) {
/////////////
// paint the numerator and denominator
nsMathMLContainerFrame::BuildDisplayList(aBuilder, aLists);
/////////////
// paint the fraction line
DisplayBar(aBuilder, this, mLineRect, aLists);
}
nsresult nsMathMLmfracFrame::AttributeChanged(int32_t aNameSpaceID,
nsAtom* aAttribute,
int32_t aModType) {
if (nsGkAtoms::linethickness_ == aAttribute) {
InvalidateFrame();
}
return nsMathMLContainerFrame::AttributeChanged(aNameSpaceID, aAttribute,
aModType);
}
/* virtual */
nsresult nsMathMLmfracFrame::MeasureForWidth(DrawTarget* aDrawTarget,
ReflowOutput& aDesiredSize) {
return PlaceInternal(aDrawTarget, false, aDesiredSize, true);
}
nscoord nsMathMLmfracFrame::FixInterFrameSpacing(ReflowOutput& aDesiredSize) {
nscoord gap = nsMathMLContainerFrame::FixInterFrameSpacing(aDesiredSize);
if (!gap) return 0;
mLineRect.MoveBy(gap, 0);
return gap;
}
/* virtual */
nsresult nsMathMLmfracFrame::Place(DrawTarget* aDrawTarget, bool aPlaceOrigin,
ReflowOutput& aDesiredSize) {
return PlaceInternal(aDrawTarget, aPlaceOrigin, aDesiredSize, false);
}
nsresult nsMathMLmfracFrame::PlaceInternal(DrawTarget* aDrawTarget,
bool aPlaceOrigin,
ReflowOutput& aDesiredSize,
bool aWidthOnly) {
////////////////////////////////////
// Get the children's desired sizes
nsBoundingMetrics bmNum, bmDen;
ReflowOutput sizeNum(aDesiredSize.GetWritingMode());
ReflowOutput sizeDen(aDesiredSize.GetWritingMode());
nsIFrame* frameDen = nullptr;
nsIFrame* frameNum = mFrames.FirstChild();
if (frameNum) frameDen = frameNum->GetNextSibling();
if (!frameNum || !frameDen || frameDen->GetNextSibling()) {
// report an error, encourage people to get their markups in order
if (aPlaceOrigin) {
ReportChildCountError();
}
return PlaceAsMrow(aDrawTarget, aPlaceOrigin, aDesiredSize);
}
GetReflowAndBoundingMetricsFor(frameNum, sizeNum, bmNum);
GetReflowAndBoundingMetricsFor(frameDen, sizeDen, bmDen);
nsPresContext* presContext = PresContext();
nscoord onePixel = nsPresContext::CSSPixelsToAppUnits(1);
float fontSizeInflation = nsLayoutUtils::FontSizeInflationFor(this);
RefPtr<nsFontMetrics> fm =
nsLayoutUtils::GetFontMetricsForFrame(this, fontSizeInflation);
nscoord defaultRuleThickness, axisHeight;
nscoord oneDevPixel = fm->AppUnitsPerDevPixel();
RefPtr<gfxFont> mathFont = fm->GetThebesFontGroup()->GetFirstMathFont();
if (mathFont) {
defaultRuleThickness = mathFont->MathTable()->Constant(
gfxMathTable::FractionRuleThickness, oneDevPixel);
} else {
GetRuleThickness(aDrawTarget, fm, defaultRuleThickness);
}
GetAxisHeight(aDrawTarget, fm, axisHeight);
bool outermostEmbellished = false;
if (mEmbellishData.coreFrame) {
nsEmbellishData parentData;
GetEmbellishDataFrom(GetParent(), parentData);
outermostEmbellished = parentData.coreFrame != mEmbellishData.coreFrame;
}
// see if the linethickness attribute is there
nsAutoString value;
mContent->AsElement()->GetAttr(nsGkAtoms::linethickness_, value);
mLineThickness =
CalcLineThickness(presContext, mComputedStyle, value, onePixel,
defaultRuleThickness, fontSizeInflation);
bool displayStyle = StyleFont()->mMathStyle == StyleMathStyle::Normal;
mLineRect.height = mLineThickness;
// by default, leave at least one-pixel padding at either end, and add
// lspace & rspace that may come from <mo> if we are an outermost
// embellished container (we fetch values from the core since they may use
// units that depend on style data, and style changes could have occurred
// in the core since our last visit there)
nscoord leftSpace = onePixel;
nscoord rightSpace = onePixel;
if (outermostEmbellished) {
const bool isRTL = StyleVisibility()->mDirection == StyleDirection::Rtl;
nsEmbellishData coreData;
GetEmbellishDataFrom(mEmbellishData.coreFrame, coreData);
leftSpace += isRTL ? coreData.trailingSpace : coreData.leadingSpace;
rightSpace += isRTL ? coreData.leadingSpace : coreData.trailingSpace;
}
nscoord actualRuleThickness = mLineThickness;
//////////////////
// Get shifts
nscoord numShift = 0;
nscoord denShift = 0;
// Rule 15b, App. G, TeXbook
nscoord numShift1, numShift2, numShift3;
nscoord denShift1, denShift2;
GetNumeratorShifts(fm, numShift1, numShift2, numShift3);
GetDenominatorShifts(fm, denShift1, denShift2);
if (0 == actualRuleThickness) {
numShift = displayStyle ? numShift1 : numShift3;
denShift = displayStyle ? denShift1 : denShift2;
if (mathFont) {
numShift = mathFont->MathTable()->Constant(
displayStyle ? gfxMathTable::StackTopDisplayStyleShiftUp
: gfxMathTable::StackTopShiftUp,
oneDevPixel);
denShift = mathFont->MathTable()->Constant(
displayStyle ? gfxMathTable::StackBottomDisplayStyleShiftDown
: gfxMathTable::StackBottomShiftDown,
oneDevPixel);
}
} else {
numShift = displayStyle ? numShift1 : numShift2;
denShift = displayStyle ? denShift1 : denShift2;
if (mathFont) {
numShift = mathFont->MathTable()->Constant(
displayStyle ? gfxMathTable::FractionNumeratorDisplayStyleShiftUp
: gfxMathTable::FractionNumeratorShiftUp,
oneDevPixel);
denShift = mathFont->MathTable()->Constant(
displayStyle ? gfxMathTable::FractionDenominatorDisplayStyleShiftDown
: gfxMathTable::FractionDenominatorShiftDown,
oneDevPixel);
}
}
if (0 == actualRuleThickness) {
// Rule 15c, App. G, TeXbook
// min clearance between numerator and denominator
nscoord minClearance =
displayStyle ? 7 * defaultRuleThickness : 3 * defaultRuleThickness;
if (mathFont) {
minClearance = mathFont->MathTable()->Constant(
displayStyle ? gfxMathTable::StackDisplayStyleGapMin
: gfxMathTable::StackGapMin,
oneDevPixel);
}
nscoord actualClearance =
(numShift - bmNum.descent) - (bmDen.ascent - denShift);
// actualClearance should be >= minClearance
if (actualClearance < minClearance) {
nscoord halfGap = (minClearance - actualClearance) / 2;
numShift += halfGap;
denShift += halfGap;
}
} else {
// Rule 15d, App. G, TeXbook
// min clearance between numerator or denominator and middle of bar
// TeX has a different interpretation of the thickness.
// Try $a \above10pt b$ to see. Here is what TeX does:
// minClearance = displayStyle ?
// 3 * actualRuleThickness : actualRuleThickness;
// we slightly depart from TeX here. We use the defaultRuleThickness
// instead of the value coming from the linethickness attribute, i.e., we
// recover what TeX does if the user hasn't set linethickness. But when
// the linethickness is set, we avoid the wide gap problem.
nscoord minClearanceNum = displayStyle ? 3 * defaultRuleThickness
: defaultRuleThickness + onePixel;
nscoord minClearanceDen = minClearanceNum;
if (mathFont) {
minClearanceNum = mathFont->MathTable()->Constant(
displayStyle ? gfxMathTable::FractionNumDisplayStyleGapMin
: gfxMathTable::FractionNumeratorGapMin,
oneDevPixel);
minClearanceDen = mathFont->MathTable()->Constant(
displayStyle ? gfxMathTable::FractionDenomDisplayStyleGapMin
: gfxMathTable::FractionDenominatorGapMin,
oneDevPixel);
}
// adjust numShift to maintain minClearanceNum if needed
nscoord actualClearanceNum =
(numShift - bmNum.descent) - (axisHeight + actualRuleThickness / 2);
if (actualClearanceNum < minClearanceNum) {
numShift += (minClearanceNum - actualClearanceNum);
}
// adjust denShift to maintain minClearanceDen if needed
nscoord actualClearanceDen =
(axisHeight - actualRuleThickness / 2) - (bmDen.ascent - denShift);
if (actualClearanceDen < minClearanceDen) {
denShift += (minClearanceDen - actualClearanceDen);
}
}
//////////////////
// Place Children
// XXX Need revisiting the width. TeX uses the exact width
// e.g. in $$\huge\frac{\displaystyle\int}{i}$$
nscoord width = std::max(bmNum.width, bmDen.width);
nscoord dxNum = leftSpace + (width - sizeNum.Width()) / 2;
nscoord dxDen = leftSpace + (width - sizeDen.Width()) / 2;
width += leftSpace + rightSpace;
mBoundingMetrics.rightBearing =
std::max(dxNum + bmNum.rightBearing, dxDen + bmDen.rightBearing);
if (mBoundingMetrics.rightBearing < width - rightSpace)
mBoundingMetrics.rightBearing = width - rightSpace;
mBoundingMetrics.leftBearing =
std::min(dxNum + bmNum.leftBearing, dxDen + bmDen.leftBearing);
if (mBoundingMetrics.leftBearing > leftSpace)
mBoundingMetrics.leftBearing = leftSpace;
mBoundingMetrics.ascent = bmNum.ascent + numShift;
mBoundingMetrics.descent = bmDen.descent + denShift;
mBoundingMetrics.width = width;
aDesiredSize.SetBlockStartAscent(sizeNum.BlockStartAscent() + numShift);
aDesiredSize.Height() = aDesiredSize.BlockStartAscent() + sizeDen.Height() -
sizeDen.BlockStartAscent() + denShift;
aDesiredSize.Width() = mBoundingMetrics.width;
aDesiredSize.mBoundingMetrics = mBoundingMetrics;
mReference.x = 0;
mReference.y = aDesiredSize.BlockStartAscent();
if (aPlaceOrigin) {
nscoord dy;
// place numerator
dy = 0;
FinishReflowChild(frameNum, presContext, sizeNum, nullptr, dxNum, dy,
ReflowChildFlags::Default);
// place denominator
dy = aDesiredSize.Height() - sizeDen.Height();
FinishReflowChild(frameDen, presContext, sizeDen, nullptr, dxDen, dy,
ReflowChildFlags::Default);
// place the fraction bar - dy is top of bar
dy = aDesiredSize.BlockStartAscent() -
(axisHeight + actualRuleThickness / 2);
mLineRect.SetRect(leftSpace, dy, width - (leftSpace + rightSpace),
actualRuleThickness);
}
return NS_OK;
}