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-rw-r--r--layout/mathml/nsMathMLmmultiscriptsFrame.cpp630
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diff --git a/layout/mathml/nsMathMLmmultiscriptsFrame.cpp b/layout/mathml/nsMathMLmmultiscriptsFrame.cpp
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+++ b/layout/mathml/nsMathMLmmultiscriptsFrame.cpp
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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
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsMathMLmmultiscriptsFrame.h"
+
+#include "mozilla/dom/Document.h"
+#include "mozilla/dom/Element.h"
+#include "mozilla/PresShell.h"
+#include "mozilla/StaticPrefs_mathml.h"
+#include "nsLayoutUtils.h"
+#include "nsPresContext.h"
+#include <algorithm>
+#include "gfxContext.h"
+#include "gfxMathTable.h"
+#include "gfxTextRun.h"
+
+using namespace mozilla;
+
+//
+// <mmultiscripts> -- attach prescripts and tensor indices to a base -
+// implementation <msub> -- attach a subscript to a base - implementation
+// <msubsup> -- attach a subscript-superscript pair to a base - implementation
+// <msup> -- attach a superscript to a base - implementation
+//
+
+nsIFrame* NS_NewMathMLmmultiscriptsFrame(PresShell* aPresShell,
+ ComputedStyle* aStyle) {
+ return new (aPresShell)
+ nsMathMLmmultiscriptsFrame(aStyle, aPresShell->GetPresContext());
+}
+
+NS_IMPL_FRAMEARENA_HELPERS(nsMathMLmmultiscriptsFrame)
+
+nsMathMLmmultiscriptsFrame::~nsMathMLmmultiscriptsFrame() = default;
+
+uint8_t nsMathMLmmultiscriptsFrame::ScriptIncrement(nsIFrame* aFrame) {
+ if (!aFrame) return 0;
+ if (mFrames.ContainsFrame(aFrame)) {
+ if (mFrames.FirstChild() == aFrame ||
+ aFrame->GetContent()->IsMathMLElement(nsGkAtoms::mprescripts_)) {
+ return 0; // No script increment for base frames or prescript markers
+ }
+ return 1;
+ }
+ return 0; // not a child
+}
+
+NS_IMETHODIMP
+nsMathMLmmultiscriptsFrame::TransmitAutomaticData() {
+ // if our base is an embellished operator, let its state bubble to us
+ mPresentationData.baseFrame = mFrames.FirstChild();
+ GetEmbellishDataFrom(mPresentationData.baseFrame, mEmbellishData);
+
+ // The TeXbook (Ch 17. p.141) says the superscript inherits the compression
+ // while the subscript is compressed. So here we collect subscripts and set
+ // the compression flag in them.
+
+ int32_t count = 0;
+ bool isSubScript = !mContent->IsMathMLElement(nsGkAtoms::msup_);
+
+ AutoTArray<nsIFrame*, 8> subScriptFrames;
+ nsIFrame* childFrame = mFrames.FirstChild();
+ while (childFrame) {
+ if (childFrame->GetContent()->IsMathMLElement(nsGkAtoms::mprescripts_)) {
+ // mprescripts frame
+ } else if (0 == count) {
+ // base frame
+ } else {
+ // super/subscript block
+ if (isSubScript) {
+ // subscript
+ subScriptFrames.AppendElement(childFrame);
+ } else {
+ // superscript
+ }
+ PropagateFrameFlagFor(childFrame, NS_FRAME_MATHML_SCRIPT_DESCENDANT);
+ isSubScript = !isSubScript;
+ }
+ count++;
+ childFrame = childFrame->GetNextSibling();
+ }
+ for (int32_t i = subScriptFrames.Length() - 1; i >= 0; i--) {
+ childFrame = subScriptFrames[i];
+ PropagatePresentationDataFor(childFrame, NS_MATHML_COMPRESSED,
+ NS_MATHML_COMPRESSED);
+ }
+
+ return NS_OK;
+}
+
+/* virtual */
+nsresult nsMathMLmmultiscriptsFrame::Place(DrawTarget* aDrawTarget,
+ bool aPlaceOrigin,
+ ReflowOutput& aDesiredSize) {
+ nscoord subScriptShift = 0;
+ nscoord supScriptShift = 0;
+ float fontSizeInflation = nsLayoutUtils::FontSizeInflationFor(this);
+
+ return PlaceMultiScript(PresContext(), aDrawTarget, aPlaceOrigin,
+ aDesiredSize, this, subScriptShift, supScriptShift,
+ fontSizeInflation);
+}
+
+// exported routine that both munderover and mmultiscripts share.
+// munderover uses this when movablelimits is set.
+nsresult nsMathMLmmultiscriptsFrame::PlaceMultiScript(
+ nsPresContext* aPresContext, DrawTarget* aDrawTarget, bool aPlaceOrigin,
+ ReflowOutput& aDesiredSize, nsMathMLContainerFrame* aFrame,
+ nscoord aUserSubScriptShift, nscoord aUserSupScriptShift,
+ float aFontSizeInflation) {
+ nsAtom* tag = aFrame->GetContent()->NodeInfo()->NameAtom();
+
+ // This function deals with both munderover etc. as well as msubsup etc.
+ // As the former behaves identically to the later, we treat it as such
+ // to avoid additional checks later.
+ if (aFrame->GetContent()->IsMathMLElement(nsGkAtoms::mover_))
+ tag = nsGkAtoms::msup_;
+ else if (aFrame->GetContent()->IsMathMLElement(nsGkAtoms::munder_))
+ tag = nsGkAtoms::msub_;
+ else if (aFrame->GetContent()->IsMathMLElement(nsGkAtoms::munderover_))
+ tag = nsGkAtoms::msubsup_;
+
+ nsBoundingMetrics bmFrame;
+
+ nscoord minShiftFromXHeight, subDrop, supDrop;
+
+ ////////////////////////////////////////
+ // Initialize super/sub shifts that
+ // depend only on the current font
+ ////////////////////////////////////////
+
+ nsIFrame* baseFrame = aFrame->PrincipalChildList().FirstChild();
+
+ if (!baseFrame) {
+ if (tag == nsGkAtoms::mmultiscripts_)
+ aFrame->ReportErrorToConsole("NoBase");
+ else
+ aFrame->ReportChildCountError();
+ return aFrame->PlaceForError(aDrawTarget, aPlaceOrigin, aDesiredSize);
+ }
+
+ // get x-height (an ex)
+ const nsStyleFont* font = aFrame->StyleFont();
+ RefPtr<nsFontMetrics> fm =
+ nsLayoutUtils::GetFontMetricsForFrame(baseFrame, aFontSizeInflation);
+
+ nscoord xHeight = fm->XHeight();
+
+ nscoord oneDevPixel = fm->AppUnitsPerDevPixel();
+ RefPtr<gfxFont> mathFont = fm->GetThebesFontGroup()->GetFirstMathFont();
+ // scriptspace from TeX for extra spacing after sup/subscript
+ nscoord scriptSpace;
+ if (mathFont) {
+ scriptSpace = mathFont->MathTable()->Constant(
+ gfxMathTable::SpaceAfterScript, oneDevPixel);
+ } else {
+ // (0.5pt in plain TeX)
+ scriptSpace = nsPresContext::CSSPointsToAppUnits(0.5f);
+ }
+
+ // Try and read sub and sup drops from the MATH table.
+ if (mathFont) {
+ subDrop = mathFont->MathTable()->Constant(
+ gfxMathTable::SubscriptBaselineDropMin, oneDevPixel);
+ supDrop = mathFont->MathTable()->Constant(
+ gfxMathTable::SuperscriptBaselineDropMax, oneDevPixel);
+ }
+
+ // force the scriptSpace to be at least 1 pixel
+ nscoord onePixel = nsPresContext::CSSPixelsToAppUnits(1);
+ scriptSpace = std::max(onePixel, scriptSpace);
+
+ /////////////////////////////////////
+ // first the shift for the subscript
+
+ nscoord subScriptShift;
+ if (mathFont) {
+ // Try and get the sub script shift from the MATH table. Note that contrary
+ // to TeX we only have one parameter.
+ subScriptShift = mathFont->MathTable()->Constant(
+ gfxMathTable::SubscriptShiftDown, oneDevPixel);
+ } else {
+ // subScriptShift{1,2}
+ // = minimum amount to shift the subscript down
+ // = sub{1,2} in TeXbook
+ // subScriptShift1 = subscriptshift attribute * x-height
+ nscoord subScriptShift1, subScriptShift2;
+ // Get subScriptShift{1,2} default from font
+ GetSubScriptShifts(fm, subScriptShift1, subScriptShift2);
+ if (tag == nsGkAtoms::msub_) {
+ subScriptShift = subScriptShift1;
+ } else {
+ subScriptShift = std::max(subScriptShift1, subScriptShift2);
+ }
+ }
+
+ if (0 < aUserSubScriptShift) {
+ // the user has set the subscriptshift attribute
+ subScriptShift = std::max(subScriptShift, aUserSubScriptShift);
+ }
+
+ /////////////////////////////////////
+ // next the shift for the superscript
+
+ nscoord supScriptShift;
+ nsPresentationData presentationData;
+ aFrame->GetPresentationData(presentationData);
+ if (mathFont) {
+ // Try and get the super script shift from the MATH table. Note that
+ // contrary to TeX we only have two parameters.
+ supScriptShift = mathFont->MathTable()->Constant(
+ NS_MATHML_IS_COMPRESSED(presentationData.flags)
+ ? gfxMathTable::SuperscriptShiftUpCramped
+ : gfxMathTable::SuperscriptShiftUp,
+ oneDevPixel);
+ } else {
+ // supScriptShift{1,2,3}
+ // = minimum amount to shift the supscript up
+ // = sup{1,2,3} in TeX
+ // supScriptShift1 = superscriptshift attribute * x-height
+ // Note that there are THREE values for supscript shifts depending
+ // on the current style
+ nscoord supScriptShift1, supScriptShift2, supScriptShift3;
+ // Set supScriptShift{1,2,3} default from font
+ GetSupScriptShifts(fm, supScriptShift1, supScriptShift2, supScriptShift3);
+
+ // get sup script shift depending on current script level and display style
+ // Rule 18c, App. G, TeXbook
+ if (font->mMathDepth == 0 && font->mMathStyle == StyleMathStyle::Normal &&
+ !NS_MATHML_IS_COMPRESSED(presentationData.flags)) {
+ // Style D in TeXbook
+ supScriptShift = supScriptShift1;
+ } else if (NS_MATHML_IS_COMPRESSED(presentationData.flags)) {
+ // Style C' in TeXbook = D',T',S',SS'
+ supScriptShift = supScriptShift3;
+ } else {
+ // everything else = T,S,SS
+ supScriptShift = supScriptShift2;
+ }
+ }
+
+ if (0 < aUserSupScriptShift) {
+ // the user has set the supscriptshift attribute
+ supScriptShift = std::max(supScriptShift, aUserSupScriptShift);
+ }
+
+ ////////////////////////////////////
+ // Get the children's sizes
+ ////////////////////////////////////
+
+ const WritingMode wm(aDesiredSize.GetWritingMode());
+ nscoord width = 0, prescriptsWidth = 0, rightBearing = 0;
+ nscoord minSubScriptShift = 0, minSupScriptShift = 0;
+ nscoord trySubScriptShift = subScriptShift;
+ nscoord trySupScriptShift = supScriptShift;
+ nscoord maxSubScriptShift = subScriptShift;
+ nscoord maxSupScriptShift = supScriptShift;
+ ReflowOutput baseSize(wm);
+ ReflowOutput subScriptSize(wm);
+ ReflowOutput supScriptSize(wm);
+ ReflowOutput multiSubSize(wm), multiSupSize(wm);
+ baseFrame = nullptr;
+ nsIFrame* subScriptFrame = nullptr;
+ nsIFrame* supScriptFrame = nullptr;
+ nsIFrame* prescriptsFrame = nullptr; // frame of <mprescripts/>, if there.
+
+ bool firstPrescriptsPair = false;
+ nsBoundingMetrics bmBase, bmSubScript, bmSupScript, bmMultiSub, bmMultiSup;
+ multiSubSize.SetBlockStartAscent(-0x7FFFFFFF);
+ multiSupSize.SetBlockStartAscent(-0x7FFFFFFF);
+ bmMultiSub.ascent = bmMultiSup.ascent = -0x7FFFFFFF;
+ bmMultiSub.descent = bmMultiSup.descent = -0x7FFFFFFF;
+ nscoord italicCorrection = 0;
+
+ nsBoundingMetrics boundingMetrics;
+ boundingMetrics.width = 0;
+ boundingMetrics.ascent = boundingMetrics.descent = -0x7FFFFFFF;
+ aDesiredSize.Width() = aDesiredSize.Height() = 0;
+
+ int32_t count = 0;
+
+ // Boolean to determine whether the current child is a subscript.
+ // Note that only msup starts with a superscript.
+ bool isSubScript = (tag != nsGkAtoms::msup_);
+
+ nsIFrame* childFrame = aFrame->PrincipalChildList().FirstChild();
+ while (childFrame) {
+ if (childFrame->GetContent()->IsMathMLElement(nsGkAtoms::mprescripts_)) {
+ if (tag != nsGkAtoms::mmultiscripts_) {
+ if (aPlaceOrigin) {
+ aFrame->ReportInvalidChildError(nsGkAtoms::mprescripts_);
+ }
+ return aFrame->PlaceForError(aDrawTarget, aPlaceOrigin, aDesiredSize);
+ }
+ if (prescriptsFrame) {
+ // duplicate <mprescripts/> found
+ // report an error, encourage people to get their markups in order
+ if (aPlaceOrigin) {
+ aFrame->ReportErrorToConsole("DuplicateMprescripts");
+ }
+ return aFrame->PlaceForError(aDrawTarget, aPlaceOrigin, aDesiredSize);
+ }
+ if (!isSubScript) {
+ if (aPlaceOrigin) {
+ aFrame->ReportErrorToConsole("SubSupMismatch");
+ }
+ return aFrame->PlaceForError(aDrawTarget, aPlaceOrigin, aDesiredSize);
+ }
+
+ prescriptsFrame = childFrame;
+ firstPrescriptsPair = true;
+ } else if (0 == count) {
+ // base
+ baseFrame = childFrame;
+ GetReflowAndBoundingMetricsFor(baseFrame, baseSize, bmBase);
+
+ if (tag != nsGkAtoms::msub_) {
+ // Apply italics correction if there is the potential for a
+ // postsupscript.
+ GetItalicCorrection(bmBase, italicCorrection);
+ // If italics correction is applied, we always add "a little to spare"
+ // (see TeXbook Ch.11, p.64), as we estimate the italic creation
+ // ourselves and it isn't the same as TeX.
+ italicCorrection += onePixel;
+ }
+
+ // we update boundingMetrics.{ascent,descent} with that
+ // of the baseFrame only after processing all the sup/sub pairs
+ boundingMetrics.width = bmBase.width;
+ boundingMetrics.rightBearing = bmBase.rightBearing;
+ boundingMetrics.leftBearing = bmBase.leftBearing; // until overwritten
+ } else {
+ // super/subscript block
+ if (isSubScript) {
+ // subscript
+ subScriptFrame = childFrame;
+ GetReflowAndBoundingMetricsFor(subScriptFrame, subScriptSize,
+ bmSubScript);
+ if (!mathFont) {
+ // get the subdrop from the subscript font
+ GetSubDropFromChild(subScriptFrame, subDrop, aFontSizeInflation);
+ }
+
+ // parameter v, Rule 18a, App. G, TeXbook
+ minSubScriptShift = bmBase.descent + subDrop;
+ trySubScriptShift = std::max(minSubScriptShift, subScriptShift);
+ multiSubSize.SetBlockStartAscent(std::max(
+ multiSubSize.BlockStartAscent(), subScriptSize.BlockStartAscent()));
+ bmMultiSub.ascent = std::max(bmMultiSub.ascent, bmSubScript.ascent);
+ bmMultiSub.descent = std::max(bmMultiSub.descent, bmSubScript.descent);
+ multiSubSize.Height() =
+ std::max(multiSubSize.Height(),
+ subScriptSize.Height() - subScriptSize.BlockStartAscent());
+ if (bmSubScript.width) width = bmSubScript.width + scriptSpace;
+ rightBearing = bmSubScript.rightBearing;
+
+ if (tag == nsGkAtoms::msub_) {
+ boundingMetrics.rightBearing = boundingMetrics.width + rightBearing;
+ boundingMetrics.width += width;
+
+ nscoord subscriptTopMax;
+ if (mathFont) {
+ subscriptTopMax = mathFont->MathTable()->Constant(
+ gfxMathTable::SubscriptTopMax, oneDevPixel);
+ } else {
+ // get min subscript shift limit from x-height
+ // = h(x) - 4/5 * sigma_5, Rule 18b, App. G, TeXbook
+ subscriptTopMax = NSToCoordRound((4.0f / 5.0f) * xHeight);
+ }
+ nscoord minShiftFromXHeight = bmSubScript.ascent - subscriptTopMax;
+ maxSubScriptShift = std::max(trySubScriptShift, minShiftFromXHeight);
+
+ maxSubScriptShift = std::max(maxSubScriptShift, trySubScriptShift);
+ trySubScriptShift = subScriptShift;
+ }
+ } else {
+ // supscript
+ supScriptFrame = childFrame;
+ GetReflowAndBoundingMetricsFor(supScriptFrame, supScriptSize,
+ bmSupScript);
+ if (!mathFont) {
+ // get the supdrop from the supscript font
+ GetSupDropFromChild(supScriptFrame, supDrop, aFontSizeInflation);
+ }
+ // parameter u, Rule 18a, App. G, TeXbook
+ minSupScriptShift = bmBase.ascent - supDrop;
+ nscoord superscriptBottomMin;
+ if (mathFont) {
+ superscriptBottomMin = mathFont->MathTable()->Constant(
+ gfxMathTable::SuperscriptBottomMin, oneDevPixel);
+ } else {
+ // get min supscript shift limit from x-height
+ // = d(x) + 1/4 * sigma_5, Rule 18c, App. G, TeXbook
+ superscriptBottomMin = NSToCoordRound((1.0f / 4.0f) * xHeight);
+ }
+ minShiftFromXHeight = bmSupScript.descent + superscriptBottomMin;
+ trySupScriptShift = std::max(
+ minSupScriptShift, std::max(minShiftFromXHeight, supScriptShift));
+ multiSupSize.SetBlockStartAscent(std::max(
+ multiSupSize.BlockStartAscent(), supScriptSize.BlockStartAscent()));
+ bmMultiSup.ascent = std::max(bmMultiSup.ascent, bmSupScript.ascent);
+ bmMultiSup.descent = std::max(bmMultiSup.descent, bmSupScript.descent);
+ multiSupSize.Height() =
+ std::max(multiSupSize.Height(),
+ supScriptSize.Height() - supScriptSize.BlockStartAscent());
+
+ if (bmSupScript.width)
+ width = std::max(width, bmSupScript.width + scriptSpace);
+
+ if (!prescriptsFrame) { // we are still looping over base & postscripts
+ rightBearing = std::max(rightBearing,
+ italicCorrection + bmSupScript.rightBearing);
+ boundingMetrics.rightBearing = boundingMetrics.width + rightBearing;
+ boundingMetrics.width += width;
+ } else {
+ prescriptsWidth += width;
+ if (firstPrescriptsPair) {
+ firstPrescriptsPair = false;
+ boundingMetrics.leftBearing =
+ std::min(bmSubScript.leftBearing, bmSupScript.leftBearing);
+ }
+ }
+ width = rightBearing = 0;
+
+ // negotiate between the various shifts so that
+ // there is enough gap between the sup and subscripts
+ // Rule 18e, App. G, TeXbook
+ if (tag == nsGkAtoms::mmultiscripts_ || tag == nsGkAtoms::msubsup_) {
+ nscoord subSuperscriptGapMin;
+ if (mathFont) {
+ subSuperscriptGapMin = mathFont->MathTable()->Constant(
+ gfxMathTable::SubSuperscriptGapMin, oneDevPixel);
+ } else {
+ nscoord ruleSize;
+ GetRuleThickness(aDrawTarget, fm, ruleSize);
+ subSuperscriptGapMin = 4 * ruleSize;
+ }
+ nscoord gap = (trySupScriptShift - bmSupScript.descent) -
+ (bmSubScript.ascent - trySubScriptShift);
+ if (gap < subSuperscriptGapMin) {
+ // adjust trySubScriptShift to get a gap of subSuperscriptGapMin
+ trySubScriptShift += subSuperscriptGapMin - gap;
+ }
+
+ // next we want to ensure that the bottom of the superscript
+ // will be > superscriptBottomMaxWithSubscript
+ nscoord superscriptBottomMaxWithSubscript;
+ if (mathFont) {
+ superscriptBottomMaxWithSubscript = mathFont->MathTable()->Constant(
+ gfxMathTable::SuperscriptBottomMaxWithSubscript, oneDevPixel);
+ } else {
+ superscriptBottomMaxWithSubscript =
+ NSToCoordRound((4.0f / 5.0f) * xHeight);
+ }
+ gap = superscriptBottomMaxWithSubscript -
+ (trySupScriptShift - bmSupScript.descent);
+ if (gap > 0) {
+ trySupScriptShift += gap;
+ trySubScriptShift -= gap;
+ }
+ }
+
+ maxSubScriptShift = std::max(maxSubScriptShift, trySubScriptShift);
+ maxSupScriptShift = std::max(maxSupScriptShift, trySupScriptShift);
+
+ trySubScriptShift = subScriptShift;
+ trySupScriptShift = supScriptShift;
+ }
+
+ isSubScript = !isSubScript;
+ }
+ count++;
+ childFrame = childFrame->GetNextSibling();
+ }
+
+ // NoBase error may also have been reported above
+ if ((count != 2 && (tag == nsGkAtoms::msup_ || tag == nsGkAtoms::msub_)) ||
+ (count != 3 && tag == nsGkAtoms::msubsup_) || !baseFrame ||
+ (!isSubScript && tag == nsGkAtoms::mmultiscripts_)) {
+ // report an error, encourage people to get their markups in order
+ if (aPlaceOrigin) {
+ if ((count != 2 &&
+ (tag == nsGkAtoms::msup_ || tag == nsGkAtoms::msub_)) ||
+ (count != 3 && tag == nsGkAtoms::msubsup_)) {
+ aFrame->ReportChildCountError();
+ } else if (!baseFrame) {
+ aFrame->ReportErrorToConsole("NoBase");
+ } else {
+ aFrame->ReportErrorToConsole("SubSupMismatch");
+ }
+ }
+ return aFrame->PlaceForError(aDrawTarget, aPlaceOrigin, aDesiredSize);
+ }
+
+ // we left out the width of prescripts, so ...
+ boundingMetrics.rightBearing += prescriptsWidth;
+ boundingMetrics.width += prescriptsWidth;
+
+ // Zero out the shifts in where a frame isn't present to avoid the potential
+ // for overflow.
+ if (!subScriptFrame) maxSubScriptShift = 0;
+ if (!supScriptFrame) maxSupScriptShift = 0;
+
+ // we left out the base during our bounding box updates, so ...
+ if (tag == nsGkAtoms::msub_) {
+ boundingMetrics.ascent =
+ std::max(bmBase.ascent, bmMultiSub.ascent - maxSubScriptShift);
+ } else {
+ boundingMetrics.ascent =
+ std::max(bmBase.ascent, (bmMultiSup.ascent + maxSupScriptShift));
+ }
+ if (tag == nsGkAtoms::msup_) {
+ boundingMetrics.descent =
+ std::max(bmBase.descent, bmMultiSup.descent - maxSupScriptShift);
+ } else {
+ boundingMetrics.descent =
+ std::max(bmBase.descent, (bmMultiSub.descent + maxSubScriptShift));
+ }
+ aFrame->SetBoundingMetrics(boundingMetrics);
+
+ // get the reflow metrics ...
+ aDesiredSize.SetBlockStartAscent(
+ std::max(baseSize.BlockStartAscent(),
+ std::max(multiSubSize.BlockStartAscent() - maxSubScriptShift,
+ multiSupSize.BlockStartAscent() + maxSupScriptShift)));
+ aDesiredSize.Height() =
+ aDesiredSize.BlockStartAscent() +
+ std::max(baseSize.Height() - baseSize.BlockStartAscent(),
+ std::max(multiSubSize.Height() + maxSubScriptShift,
+ multiSupSize.Height() - maxSupScriptShift));
+ aDesiredSize.Width() = boundingMetrics.width;
+ aDesiredSize.mBoundingMetrics = boundingMetrics;
+
+ aFrame->SetReference(nsPoint(0, aDesiredSize.BlockStartAscent()));
+
+ //////////////////
+ // Place Children
+
+ // Place prescripts, followed by base, and then postscripts.
+ // The list of frames is in the order: {base} {postscripts} {prescripts}
+ // We go over the list in a circular manner, starting at <prescripts/>
+
+ if (aPlaceOrigin) {
+ nscoord dx = 0, dy = 0;
+
+ // With msub and msup there is only one element and
+ // subscriptFrame/supScriptFrame have already been set above where
+ // relevant. In these cases we skip to the reflow part.
+ if (tag == nsGkAtoms::msub_ || tag == nsGkAtoms::msup_)
+ count = 1;
+ else
+ count = 0;
+ childFrame = prescriptsFrame;
+ bool isPreScript = true;
+ do {
+ if (!childFrame) { // end of prescripts,
+ isPreScript = false;
+ // place the base ...
+ childFrame = baseFrame;
+ dy = aDesiredSize.BlockStartAscent() - baseSize.BlockStartAscent();
+ FinishReflowChild(
+ baseFrame, aPresContext, baseSize, nullptr,
+ aFrame->MirrorIfRTL(aDesiredSize.Width(), baseSize.Width(), dx), dy,
+ ReflowChildFlags::Default);
+ dx += bmBase.width;
+ } else if (prescriptsFrame == childFrame) {
+ // Clear reflow flags of prescripts frame.
+ prescriptsFrame->DidReflow(aPresContext, nullptr);
+ } else {
+ // process each sup/sub pair
+ if (0 == count) {
+ subScriptFrame = childFrame;
+ count = 1;
+ } else if (1 == count) {
+ if (tag != nsGkAtoms::msub_) supScriptFrame = childFrame;
+ count = 0;
+
+ // get the ascent/descent of sup/subscripts stored in their rects
+ // rect.x = descent, rect.y = ascent
+ if (subScriptFrame)
+ GetReflowAndBoundingMetricsFor(subScriptFrame, subScriptSize,
+ bmSubScript);
+ if (supScriptFrame)
+ GetReflowAndBoundingMetricsFor(supScriptFrame, supScriptSize,
+ bmSupScript);
+
+ width = std::max(subScriptSize.Width(), supScriptSize.Width());
+
+ if (subScriptFrame) {
+ nscoord x = dx;
+ // prescripts should be right aligned
+ // https://bugzilla.mozilla.org/show_bug.cgi?id=928675
+ if (isPreScript) x += width - subScriptSize.Width();
+ dy = aDesiredSize.BlockStartAscent() -
+ subScriptSize.BlockStartAscent() + maxSubScriptShift;
+ FinishReflowChild(subScriptFrame, aPresContext, subScriptSize,
+ nullptr,
+ aFrame->MirrorIfRTL(aDesiredSize.Width(),
+ subScriptSize.Width(), x),
+ dy, ReflowChildFlags::Default);
+ }
+
+ if (supScriptFrame) {
+ nscoord x = dx;
+ if (isPreScript) {
+ x += width - supScriptSize.Width();
+ } else {
+ // post superscripts are shifted by the italic correction value
+ x += italicCorrection;
+ }
+ dy = aDesiredSize.BlockStartAscent() -
+ supScriptSize.BlockStartAscent() - maxSupScriptShift;
+ FinishReflowChild(supScriptFrame, aPresContext, supScriptSize,
+ nullptr,
+ aFrame->MirrorIfRTL(aDesiredSize.Width(),
+ supScriptSize.Width(), x),
+ dy, ReflowChildFlags::Default);
+ }
+ dx += width + scriptSpace;
+ }
+ }
+ childFrame = childFrame->GetNextSibling();
+ } while (prescriptsFrame != childFrame);
+ }
+
+ return NS_OK;
+}