forked from mirrors/gecko-dev
373 lines
14 KiB
C++
373 lines
14 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include "nsMathMLmfracFrame.h"
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#include "gfxUtils.h"
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#include "mozilla/gfx/2D.h"
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#include "mozilla/PresShell.h"
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#include "mozilla/RefPtr.h"
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#include "mozilla/StaticPrefs_mathml.h"
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#include "nsLayoutUtils.h"
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#include "nsPresContext.h"
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#include "nsDisplayList.h"
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#include "gfxContext.h"
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#include "mozilla/dom/Document.h"
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#include "mozilla/dom/MathMLElement.h"
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#include <algorithm>
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#include "gfxMathTable.h"
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#include "gfxTextRun.h"
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using namespace mozilla;
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using namespace mozilla::gfx;
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//
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// <mfrac> -- form a fraction from two subexpressions - implementation
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//
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nsIFrame* NS_NewMathMLmfracFrame(PresShell* aPresShell, ComputedStyle* aStyle) {
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return new (aPresShell)
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nsMathMLmfracFrame(aStyle, aPresShell->GetPresContext());
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}
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NS_IMPL_FRAMEARENA_HELPERS(nsMathMLmfracFrame)
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nsMathMLmfracFrame::~nsMathMLmfracFrame() = default;
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eMathMLFrameType nsMathMLmfracFrame::GetMathMLFrameType() {
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// frac is "inner" in TeXBook, Appendix G, rule 15e. See also page 170.
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return eMathMLFrameType_Inner;
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}
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uint8_t nsMathMLmfracFrame::ScriptIncrement(nsIFrame* aFrame) {
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if (StyleFont()->mMathStyle == StyleMathStyle::Compact && aFrame &&
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(mFrames.FirstChild() == aFrame || mFrames.LastChild() == aFrame)) {
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return 1;
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}
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return 0;
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}
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NS_IMETHODIMP
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nsMathMLmfracFrame::TransmitAutomaticData() {
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// The TeXbook (Ch 17. p.141) says the numerator inherits the compression
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// while the denominator is compressed
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UpdatePresentationDataFromChildAt(1, 1, NS_MATHML_COMPRESSED,
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NS_MATHML_COMPRESSED);
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// If displaystyle is false, then scriptlevel is incremented, so notify the
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// children of this.
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if (StyleFont()->mMathStyle == StyleMathStyle::Compact) {
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PropagateFrameFlagFor(mFrames.FirstChild(),
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NS_FRAME_MATHML_SCRIPT_DESCENDANT);
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PropagateFrameFlagFor(mFrames.LastChild(),
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NS_FRAME_MATHML_SCRIPT_DESCENDANT);
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}
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// if our numerator is an embellished operator, let its state bubble to us
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GetEmbellishDataFrom(mFrames.FirstChild(), mEmbellishData);
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if (NS_MATHML_IS_EMBELLISH_OPERATOR(mEmbellishData.flags)) {
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// even when embellished, we need to record that <mfrac> won't fire
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// Stretch() on its embellished child
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mEmbellishData.direction = NS_STRETCH_DIRECTION_UNSUPPORTED;
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}
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return NS_OK;
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}
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nscoord nsMathMLmfracFrame::CalcLineThickness(nsPresContext* aPresContext,
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ComputedStyle* aComputedStyle,
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nsString& aThicknessAttribute,
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nscoord onePixel,
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nscoord aDefaultRuleThickness,
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float aFontSizeInflation) {
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nscoord defaultThickness = aDefaultRuleThickness;
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nscoord lineThickness = aDefaultRuleThickness;
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nscoord minimumThickness = onePixel;
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// linethickness
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// https://w3c.github.io/mathml-core/#dfn-linethickness
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if (!aThicknessAttribute.IsEmpty()) {
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lineThickness = defaultThickness;
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ParseNumericValue(aThicknessAttribute, &lineThickness, 0, aPresContext,
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aComputedStyle, aFontSizeInflation);
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}
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// use minimum if the lineThickness is a non-zero value less than minimun
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if (lineThickness && lineThickness < minimumThickness)
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lineThickness = minimumThickness;
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return lineThickness;
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}
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void nsMathMLmfracFrame::BuildDisplayList(nsDisplayListBuilder* aBuilder,
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const nsDisplayListSet& aLists) {
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/////////////
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// paint the numerator and denominator
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nsMathMLContainerFrame::BuildDisplayList(aBuilder, aLists);
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/////////////
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// paint the fraction line
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DisplayBar(aBuilder, this, mLineRect, aLists);
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}
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nsresult nsMathMLmfracFrame::AttributeChanged(int32_t aNameSpaceID,
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nsAtom* aAttribute,
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int32_t aModType) {
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if (nsGkAtoms::linethickness_ == aAttribute) {
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InvalidateFrame();
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}
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return nsMathMLContainerFrame::AttributeChanged(aNameSpaceID, aAttribute,
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aModType);
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}
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/* virtual */
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nsresult nsMathMLmfracFrame::MeasureForWidth(DrawTarget* aDrawTarget,
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ReflowOutput& aDesiredSize) {
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return PlaceInternal(aDrawTarget, false, aDesiredSize, true);
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}
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nscoord nsMathMLmfracFrame::FixInterFrameSpacing(ReflowOutput& aDesiredSize) {
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nscoord gap = nsMathMLContainerFrame::FixInterFrameSpacing(aDesiredSize);
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if (!gap) return 0;
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mLineRect.MoveBy(gap, 0);
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return gap;
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}
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/* virtual */
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nsresult nsMathMLmfracFrame::Place(DrawTarget* aDrawTarget, bool aPlaceOrigin,
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ReflowOutput& aDesiredSize) {
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return PlaceInternal(aDrawTarget, aPlaceOrigin, aDesiredSize, false);
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}
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nsresult nsMathMLmfracFrame::PlaceInternal(DrawTarget* aDrawTarget,
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bool aPlaceOrigin,
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ReflowOutput& aDesiredSize,
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bool aWidthOnly) {
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////////////////////////////////////
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// Get the children's desired sizes
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nsBoundingMetrics bmNum, bmDen;
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ReflowOutput sizeNum(aDesiredSize.GetWritingMode());
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ReflowOutput sizeDen(aDesiredSize.GetWritingMode());
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nsIFrame* frameDen = nullptr;
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nsIFrame* frameNum = mFrames.FirstChild();
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if (frameNum) frameDen = frameNum->GetNextSibling();
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if (!frameNum || !frameDen || frameDen->GetNextSibling()) {
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// report an error, encourage people to get their markups in order
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if (aPlaceOrigin) {
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ReportChildCountError();
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}
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return PlaceForError(aDrawTarget, aPlaceOrigin, aDesiredSize);
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}
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GetReflowAndBoundingMetricsFor(frameNum, sizeNum, bmNum);
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GetReflowAndBoundingMetricsFor(frameDen, sizeDen, bmDen);
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nsPresContext* presContext = PresContext();
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nscoord onePixel = nsPresContext::CSSPixelsToAppUnits(1);
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float fontSizeInflation = nsLayoutUtils::FontSizeInflationFor(this);
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RefPtr<nsFontMetrics> fm =
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nsLayoutUtils::GetFontMetricsForFrame(this, fontSizeInflation);
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nscoord defaultRuleThickness, axisHeight;
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nscoord oneDevPixel = fm->AppUnitsPerDevPixel();
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RefPtr<gfxFont> mathFont = fm->GetThebesFontGroup()->GetFirstMathFont();
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if (mathFont) {
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defaultRuleThickness = mathFont->MathTable()->Constant(
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gfxMathTable::FractionRuleThickness, oneDevPixel);
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} else {
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GetRuleThickness(aDrawTarget, fm, defaultRuleThickness);
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}
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GetAxisHeight(aDrawTarget, fm, axisHeight);
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bool outermostEmbellished = false;
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if (mEmbellishData.coreFrame) {
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nsEmbellishData parentData;
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GetEmbellishDataFrom(GetParent(), parentData);
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outermostEmbellished = parentData.coreFrame != mEmbellishData.coreFrame;
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}
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// see if the linethickness attribute is there
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nsAutoString value;
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mContent->AsElement()->GetAttr(kNameSpaceID_None, nsGkAtoms::linethickness_,
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value);
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mLineThickness =
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CalcLineThickness(presContext, mComputedStyle, value, onePixel,
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defaultRuleThickness, fontSizeInflation);
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bool displayStyle = StyleFont()->mMathStyle == StyleMathStyle::Normal;
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mLineRect.height = mLineThickness;
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// by default, leave at least one-pixel padding at either end, and add
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// lspace & rspace that may come from <mo> if we are an outermost
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// embellished container (we fetch values from the core since they may use
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// units that depend on style data, and style changes could have occurred
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// in the core since our last visit there)
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nscoord leftSpace = onePixel;
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nscoord rightSpace = onePixel;
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if (outermostEmbellished) {
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const bool isRTL = StyleVisibility()->mDirection == StyleDirection::Rtl;
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nsEmbellishData coreData;
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GetEmbellishDataFrom(mEmbellishData.coreFrame, coreData);
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leftSpace += isRTL ? coreData.trailingSpace : coreData.leadingSpace;
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rightSpace += isRTL ? coreData.leadingSpace : coreData.trailingSpace;
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}
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nscoord actualRuleThickness = mLineThickness;
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//////////////////
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// Get shifts
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nscoord numShift = 0;
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nscoord denShift = 0;
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// Rule 15b, App. G, TeXbook
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nscoord numShift1, numShift2, numShift3;
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nscoord denShift1, denShift2;
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GetNumeratorShifts(fm, numShift1, numShift2, numShift3);
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GetDenominatorShifts(fm, denShift1, denShift2);
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if (0 == actualRuleThickness) {
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numShift = displayStyle ? numShift1 : numShift3;
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denShift = displayStyle ? denShift1 : denShift2;
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if (mathFont) {
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numShift = mathFont->MathTable()->Constant(
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displayStyle ? gfxMathTable::StackTopDisplayStyleShiftUp
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: gfxMathTable::StackTopShiftUp,
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oneDevPixel);
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denShift = mathFont->MathTable()->Constant(
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displayStyle ? gfxMathTable::StackBottomDisplayStyleShiftDown
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: gfxMathTable::StackBottomShiftDown,
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oneDevPixel);
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}
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} else {
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numShift = displayStyle ? numShift1 : numShift2;
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denShift = displayStyle ? denShift1 : denShift2;
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if (mathFont) {
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numShift = mathFont->MathTable()->Constant(
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displayStyle ? gfxMathTable::FractionNumeratorDisplayStyleShiftUp
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: gfxMathTable::FractionNumeratorShiftUp,
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oneDevPixel);
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denShift = mathFont->MathTable()->Constant(
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displayStyle ? gfxMathTable::FractionDenominatorDisplayStyleShiftDown
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: gfxMathTable::FractionDenominatorShiftDown,
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oneDevPixel);
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}
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}
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if (0 == actualRuleThickness) {
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// Rule 15c, App. G, TeXbook
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// min clearance between numerator and denominator
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nscoord minClearance =
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displayStyle ? 7 * defaultRuleThickness : 3 * defaultRuleThickness;
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if (mathFont) {
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minClearance = mathFont->MathTable()->Constant(
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displayStyle ? gfxMathTable::StackDisplayStyleGapMin
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: gfxMathTable::StackGapMin,
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oneDevPixel);
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}
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nscoord actualClearance =
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(numShift - bmNum.descent) - (bmDen.ascent - denShift);
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// actualClearance should be >= minClearance
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if (actualClearance < minClearance) {
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nscoord halfGap = (minClearance - actualClearance) / 2;
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numShift += halfGap;
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denShift += halfGap;
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}
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} else {
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// Rule 15d, App. G, TeXbook
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// min clearance between numerator or denominator and middle of bar
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// TeX has a different interpretation of the thickness.
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// Try $a \above10pt b$ to see. Here is what TeX does:
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// minClearance = displayStyle ?
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// 3 * actualRuleThickness : actualRuleThickness;
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// we slightly depart from TeX here. We use the defaultRuleThickness
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// instead of the value coming from the linethickness attribute, i.e., we
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// recover what TeX does if the user hasn't set linethickness. But when
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// the linethickness is set, we avoid the wide gap problem.
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nscoord minClearanceNum = displayStyle ? 3 * defaultRuleThickness
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: defaultRuleThickness + onePixel;
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nscoord minClearanceDen = minClearanceNum;
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if (mathFont) {
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minClearanceNum = mathFont->MathTable()->Constant(
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displayStyle ? gfxMathTable::FractionNumDisplayStyleGapMin
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: gfxMathTable::FractionNumeratorGapMin,
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oneDevPixel);
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minClearanceDen = mathFont->MathTable()->Constant(
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displayStyle ? gfxMathTable::FractionDenomDisplayStyleGapMin
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: gfxMathTable::FractionDenominatorGapMin,
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oneDevPixel);
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}
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// adjust numShift to maintain minClearanceNum if needed
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nscoord actualClearanceNum =
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(numShift - bmNum.descent) - (axisHeight + actualRuleThickness / 2);
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if (actualClearanceNum < minClearanceNum) {
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numShift += (minClearanceNum - actualClearanceNum);
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}
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// adjust denShift to maintain minClearanceDen if needed
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nscoord actualClearanceDen =
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(axisHeight - actualRuleThickness / 2) - (bmDen.ascent - denShift);
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if (actualClearanceDen < minClearanceDen) {
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denShift += (minClearanceDen - actualClearanceDen);
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}
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}
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//////////////////
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// Place Children
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// XXX Need revisiting the width. TeX uses the exact width
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// e.g. in $$\huge\frac{\displaystyle\int}{i}$$
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nscoord width = std::max(bmNum.width, bmDen.width);
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nscoord dxNum = leftSpace + (width - sizeNum.Width()) / 2;
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nscoord dxDen = leftSpace + (width - sizeDen.Width()) / 2;
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width += leftSpace + rightSpace;
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mBoundingMetrics.rightBearing =
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std::max(dxNum + bmNum.rightBearing, dxDen + bmDen.rightBearing);
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if (mBoundingMetrics.rightBearing < width - rightSpace)
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mBoundingMetrics.rightBearing = width - rightSpace;
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mBoundingMetrics.leftBearing =
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std::min(dxNum + bmNum.leftBearing, dxDen + bmDen.leftBearing);
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if (mBoundingMetrics.leftBearing > leftSpace)
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mBoundingMetrics.leftBearing = leftSpace;
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mBoundingMetrics.ascent = bmNum.ascent + numShift;
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mBoundingMetrics.descent = bmDen.descent + denShift;
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mBoundingMetrics.width = width;
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aDesiredSize.SetBlockStartAscent(sizeNum.BlockStartAscent() + numShift);
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aDesiredSize.Height() = aDesiredSize.BlockStartAscent() + sizeDen.Height() -
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sizeDen.BlockStartAscent() + denShift;
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aDesiredSize.Width() = mBoundingMetrics.width;
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aDesiredSize.mBoundingMetrics = mBoundingMetrics;
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mReference.x = 0;
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mReference.y = aDesiredSize.BlockStartAscent();
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if (aPlaceOrigin) {
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nscoord dy;
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// place numerator
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dy = 0;
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FinishReflowChild(frameNum, presContext, sizeNum, nullptr, dxNum, dy,
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ReflowChildFlags::Default);
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// place denominator
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dy = aDesiredSize.Height() - sizeDen.Height();
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FinishReflowChild(frameDen, presContext, sizeDen, nullptr, dxDen, dy,
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ReflowChildFlags::Default);
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// place the fraction bar - dy is top of bar
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dy = aDesiredSize.BlockStartAscent() -
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(axisHeight + actualRuleThickness / 2);
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mLineRect.SetRect(leftSpace, dy, width - (leftSpace + rightSpace),
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actualRuleThickness);
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}
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return NS_OK;
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}
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