gecko-dev/layout/mathml/nsMathMLmmultiscriptsFrame.cpp

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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 "nsCOMPtr.h"
#include "nsFrame.h"
#include "nsPresContext.h"
#include "nsStyleContext.h"
#include "nsStyleConsts.h"
#include "nsRenderingContext.h"
#include "nsMathMLmmultiscriptsFrame.h"
#include <algorithm>
//
// <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(nsIPresShell* aPresShell, nsStyleContext* aContext)
{
return new (aPresShell) nsMathMLmmultiscriptsFrame(aContext);
}
NS_IMPL_FRAMEARENA_HELPERS(nsMathMLmmultiscriptsFrame)
nsMathMLmmultiscriptsFrame::~nsMathMLmmultiscriptsFrame()
{
}
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 REC says:
// The script element increments scriptlevel by 1, and sets
// displaystyle to "false", within each of its arguments except base
UpdatePresentationDataFromChildAt(1, -1,
~NS_MATHML_DISPLAYSTYLE, NS_MATHML_DISPLAYSTYLE);
// 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.
if (mContent->Tag() == nsGkAtoms::msup_)
return NS_OK;
int32_t count = 0;
bool isSubScript = true;
nsAutoTArray<nsIFrame*, 8> subScriptFrames;
nsIFrame* childFrame = mFrames.FirstChild();
while (childFrame) {
if (childFrame->GetContent()->Tag() == nsGkAtoms::mprescripts_) {
// mprescripts frame
} else if (0 == count) {
// base frame
} else {
// super/subscript block
if (isSubScript) {
// subscript
subScriptFrames.AppendElement(childFrame);
} else {
// superscript
}
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(nsRenderingContext& aRenderingContext,
bool aPlaceOrigin,
nsHTMLReflowMetrics& aDesiredSize)
{
nscoord subScriptShift = 0;
nscoord supScriptShift = 0;
nsIAtom* tag = mContent->Tag();
// subscriptshift
//
// "Specifies the minimum amount to shift the baseline of subscript down; the
// default is for the rendering agent to use its own positioning rules."
//
// values: length
// default: automatic
//
// We use 0 as the default value so unitless values can be ignored.
// As a minimum, negative values can be ignored.
//
nsAutoString value;
if (tag != nsGkAtoms::msup_) {
GetAttribute(mContent, mPresentationData.mstyle,
nsGkAtoms::subscriptshift_, value);
if (!value.IsEmpty()) {
ParseNumericValue(value, &subScriptShift, 0, PresContext(),
mStyleContext);
}
}
// superscriptshift
//
// "Specifies the minimum amount to shift the baseline of superscript up; the
// default is for the rendering agent to use its own positioning rules."
//
// values: length
// default: automatic
//
// We use 0 as the default value so unitless values can be ignored.
// As a minimum, negative values can be ignored.
//
if (tag != nsGkAtoms::msub_) {
GetAttribute(mContent, mPresentationData.mstyle,
nsGkAtoms::superscriptshift_, value);
if (!value.IsEmpty()) {
ParseNumericValue(value, &supScriptShift, 0, PresContext(),
mStyleContext);
}
}
// scriptspace from TeX for extra spacing after sup/subscript
// (0.5pt in plain TeX)
nscoord scriptSpace = nsPresContext::CSSPointsToAppUnits(0.5f);
return PlaceMultiScript(PresContext(), aRenderingContext, aPlaceOrigin,
aDesiredSize, this, subScriptShift, supScriptShift,
scriptSpace);
}
// exported routine that both munderover and mmultiscripts share.
// munderover uses this when movablelimits is set.
nsresult
nsMathMLmmultiscriptsFrame::PlaceMultiScript(nsPresContext* aPresContext,
nsRenderingContext& aRenderingContext,
bool aPlaceOrigin,
nsHTMLReflowMetrics& aDesiredSize,
nsMathMLContainerFrame* aFrame,
nscoord aUserSubScriptShift,
nscoord aUserSupScriptShift,
nscoord aScriptSpace)
{
nsIAtom* tag = aFrame->GetContent()->Tag();
// 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 (tag == nsGkAtoms::mover_)
tag = nsGkAtoms::msup_;
else if (tag == nsGkAtoms::munder_)
tag = nsGkAtoms::msub_;
else if (tag == nsGkAtoms::munderover_)
tag = nsGkAtoms::msubsup_;
nsBoundingMetrics bmFrame;
nsHTMLReflowMetrics frameSize;
nscoord minShiftFromXHeight, subDrop, supDrop;
////////////////////////////////////////
// Initialize super/sub shifts that
// depend only on the current font
////////////////////////////////////////
nsIFrame* baseFrame = aFrame->GetFirstPrincipalChild();
if (!baseFrame) {
if (tag == nsGkAtoms::mmultiscripts_)
aFrame->ReportErrorToConsole("NoBase");
else
aFrame->ReportChildCountError();
return aFrame->ReflowError(aRenderingContext, aDesiredSize);
}
// get x-height (an ex)
const nsStyleFont* font = aFrame->StyleFont();
nsRefPtr<nsFontMetrics> fm;
nsLayoutUtils::GetFontMetricsForFrame(baseFrame, getter_AddRefs(fm));
aRenderingContext.SetFont(fm);
nscoord xHeight = fm->XHeight();
nscoord ruleSize;
GetRuleThickness (aRenderingContext, fm, ruleSize);
// force the scriptSpace to be at least 1 pixel
nscoord onePixel = nsPresContext::CSSPixelsToAppUnits(1);
aScriptSpace = std::max(onePixel, aScriptSpace);
/////////////////////////////////////
// first the shift for the subscript
// 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);
nscoord subScriptShift;
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
// 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
nsPresentationData presentationData;
aFrame->GetPresentationData(presentationData);
nscoord supScriptShift;
if ( font->mScriptLevel == 0 &&
NS_MATHML_IS_DISPLAYSTYLE(presentationData.flags) &&
!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
////////////////////////////////////
nscoord width = 0, prescriptsWidth = 0, rightBearing = 0;
nscoord minSubScriptShift = 0, minSupScriptShift = 0;
nscoord trySubScriptShift = subScriptShift;
nscoord trySupScriptShift = supScriptShift;
nscoord maxSubScriptShift = subScriptShift;
nscoord maxSupScriptShift = supScriptShift;
nsHTMLReflowMetrics baseSize;
nsHTMLReflowMetrics subScriptSize;
nsHTMLReflowMetrics supScriptSize;
nsHTMLReflowMetrics multiSubSize, multiSupSize;
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.ascent = multiSupSize.ascent = -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;
bool foundNoneTag = false;
// 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->GetFirstPrincipalChild();
while (childFrame) {
nsIAtom* childTag = childFrame->GetContent()->Tag();
if (childTag == nsGkAtoms::mprescripts_) {
if (tag != nsGkAtoms::mmultiscripts_) {
if (aPlaceOrigin) {
aFrame->ReportInvalidChildError(childTag);
}
return aFrame->ReflowError(aRenderingContext, aDesiredSize);
}
if (prescriptsFrame) {
// duplicate <mprescripts/> found
// report an error, encourage people to get their markups in order
if (aPlaceOrigin) {
aFrame->ReportErrorToConsole("DuplicateMprescripts");
}
return aFrame->ReflowError(aRenderingContext, aDesiredSize);
}
if (!isSubScript) {
if (aPlaceOrigin) {
aFrame->ReportErrorToConsole("SubSupMismatch");
}
return aFrame->ReflowError(aRenderingContext, aDesiredSize);
}
prescriptsFrame = childFrame;
firstPrescriptsPair = true;
} else if (0 == count) {
// base
if (childTag == nsGkAtoms::none) {
if (tag == nsGkAtoms::mmultiscripts_) {
if (aPlaceOrigin) {
aFrame->ReportErrorToConsole("NoBase");
}
return aFrame->ReflowError(aRenderingContext, aDesiredSize);
} else {
//A different error message is triggered later for the other tags
foundNoneTag = true;
}
}
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
// XXX need italic correction only *if* there are postscripts ?
boundingMetrics.width = bmBase.width + italicCorrection;
boundingMetrics.rightBearing = bmBase.rightBearing;
boundingMetrics.leftBearing = bmBase.leftBearing; // until overwritten
} else {
// super/subscript block
if ( childTag == nsGkAtoms::none) {
foundNoneTag = true;
}
if (isSubScript) {
// subscript
subScriptFrame = childFrame;
GetReflowAndBoundingMetricsFor(subScriptFrame, subScriptSize, bmSubScript);
// get the subdrop from the subscript font
GetSubDropFromChild (subScriptFrame, subDrop);
// parameter v, Rule 18a, App. G, TeXbook
minSubScriptShift = bmBase.descent + subDrop;
trySubScriptShift = std::max(minSubScriptShift,subScriptShift);
multiSubSize.ascent = std::max(multiSubSize.ascent,
subScriptSize.ascent);
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.ascent);
if (bmSubScript.width)
width = bmSubScript.width + aScriptSpace;
rightBearing = bmSubScript.rightBearing;
if (tag == nsGkAtoms::msub_) {
boundingMetrics.rightBearing = boundingMetrics.width + rightBearing;
boundingMetrics.width += width;
// get min subscript shift limit from x-height
// = h(x) - 4/5 * sigma_5, Rule 18b, App. G, TeXbook
nscoord minShiftFromXHeight = (nscoord)
(bmSubScript.ascent - (4.0f/5.0f) * xHeight);
maxSubScriptShift = std::max(trySubScriptShift,minShiftFromXHeight);
maxSubScriptShift = std::max(maxSubScriptShift, trySubScriptShift);
trySubScriptShift = subScriptShift;
}
} else {
// supscript
supScriptFrame = childFrame;
GetReflowAndBoundingMetricsFor(supScriptFrame, supScriptSize, bmSupScript);
// get the supdrop from the supscript font
GetSupDropFromChild (supScriptFrame, supDrop);
// parameter u, Rule 18a, App. G, TeXbook
minSupScriptShift = bmBase.ascent - supDrop;
// get min supscript shift limit from x-height
// = d(x) + 1/4 * sigma_5, Rule 18c, App. G, TeXbook
minShiftFromXHeight = NSToCoordRound
((bmSupScript.descent + (1.0f/4.0f) * xHeight));
trySupScriptShift = std::max(minSupScriptShift,
std::max(minShiftFromXHeight,
supScriptShift));
multiSupSize.ascent = std::max(multiSupSize.ascent,
supScriptSize.ascent);
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.ascent);
if (bmSupScript.width)
width = std::max(width, bmSupScript.width + aScriptSpace);
rightBearing = std::max(rightBearing, bmSupScript.rightBearing);
if (!prescriptsFrame) { // we are still looping over base & postscripts
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 gap =
(trySupScriptShift - bmSupScript.descent) -
(bmSubScript.ascent - trySubScriptShift);
if (gap < 4.0f * ruleSize) {
// adjust trySubScriptShift to get a gap of (4.0 * ruleSize)
trySubScriptShift += NSToCoordRound ((4.0f * ruleSize) - gap);
}
// next we want to ensure that the bottom of the superscript
// will be > (4/5) * x-height above baseline
gap = NSToCoordRound ((4.0f/5.0f) * xHeight -
(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 ||
(foundNoneTag && tag != nsGkAtoms::mmultiscripts_) ||
(!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 (foundNoneTag && tag != nsGkAtoms::mmultiscripts_) {
aFrame->ReportInvalidChildError(nsGkAtoms::none);
} else if (!baseFrame) {
aFrame->ReportErrorToConsole("NoBase");
} else {
aFrame->ReportErrorToConsole("SubSupMismatch");
}
}
return aFrame->ReflowError(aRenderingContext, 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.ascent =
std::max(baseSize.ascent,
std::max(multiSubSize.ascent - maxSubScriptShift,
multiSupSize.ascent + maxSupScriptShift));
aDesiredSize.height = aDesiredSize.ascent +
std::max(baseSize.height - baseSize.ascent,
std::max(multiSubSize.height + maxSubScriptShift,
multiSupSize.height - maxSupScriptShift));
aDesiredSize.width = boundingMetrics.width;
aDesiredSize.mBoundingMetrics = boundingMetrics;
aFrame->SetReference(nsPoint(0, aDesiredSize.ascent));
//////////////////
// 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;
do {
if (!childFrame) { // end of prescripts,
// place the base ...
childFrame = baseFrame;
dy = aDesiredSize.ascent - baseSize.ascent;
FinishReflowChild (baseFrame, aPresContext, nullptr, baseSize,
aFrame->MirrorIfRTL(aDesiredSize.width,
baseSize.width,
dx),
dy, 0);
dx += bmBase.width + italicCorrection;
} else if (prescriptsFrame != childFrame) {
// 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);
// center w.r.t. largest width
width = std::max(subScriptSize.width, supScriptSize.width);
if (subScriptFrame) {
dy = aDesiredSize.ascent - subScriptSize.ascent +
maxSubScriptShift;
FinishReflowChild (subScriptFrame, aPresContext, nullptr,
subScriptSize,
aFrame->MirrorIfRTL(aDesiredSize.width,
subScriptSize.width,
dx + (width-subScriptSize.width)/2),
dy, 0);
}
if (supScriptFrame) {
dy = aDesiredSize.ascent - supScriptSize.ascent -
maxSupScriptShift;
FinishReflowChild (supScriptFrame, aPresContext, nullptr,
supScriptSize,
aFrame->MirrorIfRTL(aDesiredSize.width,
supScriptSize.width,
dx + (width-supScriptSize.width)/2),
dy, 0);
}
dx += width + aScriptSpace;
}
}
childFrame = childFrame->GetNextSibling();
} while (prescriptsFrame != childFrame);
}
return NS_OK;
}