gecko-dev/layout/mathml/nsMathMLmfracFrame.cpp

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is Mozilla MathML Project.
*
* The Initial Developer of the Original Code is
* The University Of Queensland.
* Portions created by the Initial Developer are Copyright (C) 1999
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Roger B. Sidje <rbs@maths.uq.edu.au>
* David J. Fiddes <D.J.Fiddes@hw.ac.uk>
* Shyjan Mahamud <mahamud@cs.cmu.edu>
*
* Alternatively, the contents of this file may be used under the terms of
* either of the GNU General Public License Version 2 or later (the "GPL"),
* or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
#include "nsCOMPtr.h"
#include "nsFrame.h"
#include "nsPresContext.h"
#include "nsStyleContext.h"
#include "nsStyleConsts.h"
#include "nsIRenderingContext.h"
#include "nsIFontMetrics.h"
#include "nsMathMLmfencedFrame.h"
#include "nsMathMLmfracFrame.h"
//
// <mfrac> -- form a fraction from two subexpressions - implementation
//
// various fraction line thicknesses (multiplicative values of the default rule thickness)
#define THIN_FRACTION_LINE 0.5f
#define THIN_FRACTION_LINE_MINIMUM_PIXELS 1 // minimum of 1 pixel
#define MEDIUM_FRACTION_LINE 1.5f
#define MEDIUM_FRACTION_LINE_MINIMUM_PIXELS 2 // minimum of 2 pixels
#define THICK_FRACTION_LINE 2.0f
#define THICK_FRACTION_LINE_MINIMUM_PIXELS 4 // minimum of 4 pixels
// additional style context to be used by our MathMLChar.
#define NS_SLASH_CHAR_STYLE_CONTEXT_INDEX 0
static const PRUnichar kSlashChar = PRUnichar('/');
nsIFrame*
NS_NewMathMLmfracFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)
{
return new (aPresShell) nsMathMLmfracFrame(aContext);
}
NS_IMPL_FRAMEARENA_HELPERS(nsMathMLmfracFrame)
nsMathMLmfracFrame::~nsMathMLmfracFrame()
{
if (mSlashChar) {
delete mSlashChar;
mSlashChar = nsnull;
}
}
PRBool
nsMathMLmfracFrame::IsBevelled()
{
nsAutoString value;
GetAttribute(mContent, mPresentationData.mstyle, nsGkAtoms::bevelled_,
value);
return value.EqualsLiteral("true");
}
NS_IMETHODIMP
nsMathMLmfracFrame::Init(nsIContent* aContent,
nsIFrame* aParent,
nsIFrame* aPrevInFlow)
{
nsresult rv = nsMathMLContainerFrame::Init(aContent, aParent, aPrevInFlow);
if (IsBevelled()) {
// enable the bevelled rendering
mSlashChar = new nsMathMLChar();
if (mSlashChar) {
nsPresContext* presContext = PresContext();
nsAutoString slashChar; slashChar.Assign(kSlashChar);
mSlashChar->SetData(presContext, slashChar);
ResolveMathMLCharStyle(presContext, mContent, mStyleContext, mSlashChar, PR_TRUE);
}
}
return rv;
}
eMathMLFrameType
nsMathMLmfracFrame::GetMathMLFrameType()
{
// frac is "inner" in TeXBook, Appendix G, rule 15e. See also page 170.
return eMathMLFrameType_Inner;
}
NS_IMETHODIMP
nsMathMLmfracFrame::TransmitAutomaticData()
{
// 1. The REC says:
// The <mfrac> element sets displaystyle to "false", or if it was already
// false increments scriptlevel by 1, within numerator and denominator.
// 2. The TeXbook (Ch 17. p.141) says the numerator inherits the compression
// while the denominator is compressed
PRBool increment = !NS_MATHML_IS_DISPLAYSTYLE(mPresentationData.flags);
SetIncrementScriptLevel(0, increment);
SetIncrementScriptLevel(1, increment);
UpdatePresentationDataFromChildAt(0, -1,
~NS_MATHML_DISPLAYSTYLE,
NS_MATHML_DISPLAYSTYLE);
UpdatePresentationDataFromChildAt(1, 1,
NS_MATHML_COMPRESSED,
NS_MATHML_COMPRESSED);
// 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,
nsStyleContext* aStyleContext,
nsString& aThicknessAttribute,
nscoord onePixel,
nscoord aDefaultRuleThickness)
{
nscoord defaultThickness = aDefaultRuleThickness;
nscoord lineThickness = aDefaultRuleThickness;
nscoord minimumThickness = onePixel;
if (!aThicknessAttribute.IsEmpty()) {
if (aThicknessAttribute.EqualsLiteral("thin")) {
lineThickness = NSToCoordFloor(defaultThickness * THIN_FRACTION_LINE);
minimumThickness = onePixel * THIN_FRACTION_LINE_MINIMUM_PIXELS;
// should visually decrease by at least one pixel, if default is not a pixel
if (defaultThickness > onePixel && lineThickness > defaultThickness - onePixel)
lineThickness = defaultThickness - onePixel;
}
else if (aThicknessAttribute.EqualsLiteral("medium")) {
lineThickness = NSToCoordRound(defaultThickness * MEDIUM_FRACTION_LINE);
minimumThickness = onePixel * MEDIUM_FRACTION_LINE_MINIMUM_PIXELS;
// should visually increase by at least one pixel
if (lineThickness < defaultThickness + onePixel)
lineThickness = defaultThickness + onePixel;
}
else if (aThicknessAttribute.EqualsLiteral("thick")) {
lineThickness = NSToCoordCeil(defaultThickness * THICK_FRACTION_LINE);
minimumThickness = onePixel * THICK_FRACTION_LINE_MINIMUM_PIXELS;
// should visually increase by at least two pixels
if (lineThickness < defaultThickness + 2*onePixel)
lineThickness = defaultThickness + 2*onePixel;
}
else { // see if it is a plain number, or a percentage, or a h/v-unit like 1ex, 2px, 1em
nsCSSValue cssValue;
if (ParseNumericValue(aThicknessAttribute, cssValue)) {
nsCSSUnit unit = cssValue.GetUnit();
if (eCSSUnit_Number == unit)
lineThickness = nscoord(float(defaultThickness) * cssValue.GetFloatValue());
else if (eCSSUnit_Percent == unit)
lineThickness = nscoord(float(defaultThickness) * cssValue.GetPercentValue());
else if (eCSSUnit_Null != unit)
lineThickness = CalcLength(aPresContext, aStyleContext, cssValue);
}
}
}
// use minimum if the lineThickness is a non-zero value less than minimun
if (lineThickness && lineThickness < minimumThickness)
lineThickness = minimumThickness;
return lineThickness;
}
NS_IMETHODIMP
nsMathMLmfracFrame::BuildDisplayList(nsDisplayListBuilder* aBuilder,
const nsRect& aDirtyRect,
const nsDisplayListSet& aLists)
{
/////////////
// paint the numerator and denominator
nsresult rv = nsMathMLContainerFrame::BuildDisplayList(aBuilder, aDirtyRect, aLists);
NS_ENSURE_SUCCESS(rv, rv);
/////////////
// paint the fraction line
if (mSlashChar) {
// bevelled rendering
rv = mSlashChar->Display(aBuilder, this, aLists);
} else {
rv = DisplayBar(aBuilder, this, mLineRect, aLists);
}
return rv;
}
NS_IMETHODIMP
nsMathMLmfracFrame::Reflow(nsPresContext* aPresContext,
nsHTMLReflowMetrics& aDesiredSize,
const nsHTMLReflowState& aReflowState,
nsReflowStatus& aStatus)
{
if (mSlashChar) {
// bevelled rendering
return nsMathMLmfencedFrame::doReflow(aPresContext, aReflowState,
aDesiredSize, aStatus, this,
nsnull, nsnull, mSlashChar, 1);
}
// default rendering
return nsMathMLContainerFrame::Reflow(aPresContext, aDesiredSize,
aReflowState, aStatus);
}
/* virtual */ nscoord
nsMathMLmfracFrame::GetIntrinsicWidth(nsIRenderingContext* aRenderingContext)
{
if (mSlashChar) {
// bevelled rendering
return nsMathMLmfencedFrame::doGetIntrinsicWidth(aRenderingContext, this,
nsnull, nsnull,
mSlashChar, 1);
}
// default rendering
return nsMathMLContainerFrame::GetIntrinsicWidth(aRenderingContext);
}
nscoord
nsMathMLmfracFrame::FixInterFrameSpacing(nsHTMLReflowMetrics& aDesiredSize)
{
nscoord gap = nsMathMLContainerFrame::FixInterFrameSpacing(aDesiredSize);
if (!gap) return 0;
if (mSlashChar) {
nsRect rect;
mSlashChar->GetRect(rect);
rect.MoveBy(gap, 0);
mSlashChar->SetRect(rect);
}
else {
mLineRect.MoveBy(gap, 0);
}
return gap;
}
/* virtual */ nsresult
nsMathMLmfracFrame::Place(nsIRenderingContext& aRenderingContext,
PRBool aPlaceOrigin,
nsHTMLReflowMetrics& aDesiredSize)
{
////////////////////////////////////
// Get the children's desired sizes
nsBoundingMetrics bmNum, bmDen;
nsHTMLReflowMetrics sizeNum;
nsHTMLReflowMetrics sizeDen;
nsIFrame* frameDen = nsnull;
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
return ReflowError(aRenderingContext, aDesiredSize);
}
GetReflowAndBoundingMetricsFor(frameNum, sizeNum, bmNum);
GetReflowAndBoundingMetricsFor(frameDen, sizeDen, bmDen);
//////////////////
// Get shifts
nsPresContext* presContext = PresContext();
nscoord onePixel = nsPresContext::CSSPixelsToAppUnits(1);
aRenderingContext.SetFont(GetStyleFont()->mFont, nsnull,
presContext->GetUserFontSet());
nsCOMPtr<nsIFontMetrics> fm;
aRenderingContext.GetFontMetrics(*getter_AddRefs(fm));
nscoord defaultRuleThickness, axisHeight;
GetRuleThickness(aRenderingContext, fm, defaultRuleThickness);
GetAxisHeight(aRenderingContext, fm, axisHeight);
// by default, leave at least one-pixel padding at either end, or use
// lspace & rspace that may come from <mo> if we are an 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)
nsEmbellishData coreData;
GetEmbellishDataFrom(mEmbellishData.coreFrame, coreData);
nscoord leftSpace = NS_MAX(onePixel, coreData.leftSpace);
nscoord rightSpace = NS_MAX(onePixel, coreData.rightSpace);
// see if the linethickness attribute is there
nsAutoString value;
GetAttribute(mContent, mPresentationData.mstyle, nsGkAtoms::linethickness_, value);
mLineRect.height = CalcLineThickness(presContext, mStyleContext, value,
onePixel, defaultRuleThickness);
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 (NS_MATHML_IS_DISPLAYSTYLE(mPresentationData.flags)) {
// C > T
numShift = numShift1;
denShift = denShift1;
}
else {
numShift = (0 < mLineRect.height) ? numShift2 : numShift3;
denShift = denShift2;
}
nscoord minClearance = 0;
nscoord actualClearance = 0;
nscoord actualRuleThickness = mLineRect.height;
if (0 == actualRuleThickness) {
// Rule 15c, App. G, TeXbook
// min clearance between numerator and denominator
minClearance = (NS_MATHML_IS_DISPLAYSTYLE(mPresentationData.flags)) ?
7 * defaultRuleThickness : 3 * defaultRuleThickness;
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 = (NS_MATHML_IS_DISPLAYSTYLE(mPresentationData.flags)) ?
// 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.
minClearance = (NS_MATHML_IS_DISPLAYSTYLE(mPresentationData.flags)) ?
3 * defaultRuleThickness : defaultRuleThickness + onePixel;
// adjust numShift to maintain minClearance if needed
actualClearance =
(numShift - bmNum.descent) - (axisHeight + actualRuleThickness/2);
if (actualClearance < minClearance) {
numShift += (minClearance - actualClearance);
}
// adjust denShift to maintain minClearance if needed
actualClearance =
(axisHeight - actualRuleThickness/2) - (bmDen.ascent - denShift);
if (actualClearance < minClearance) {
denShift += (minClearance - actualClearance);
}
}
//////////////////
// Place Children
// XXX Need revisiting the width. TeX uses the exact width
// e.g. in $$\huge\frac{\displaystyle\int}{i}$$
nscoord width = NS_MAX(bmNum.width, bmDen.width);
nscoord dxNum = leftSpace + (width - sizeNum.width)/2;
nscoord dxDen = leftSpace + (width - sizeDen.width)/2;
width += leftSpace + rightSpace;
// see if the numalign attribute is there
GetAttribute(mContent, mPresentationData.mstyle, nsGkAtoms::numalign_,
value);
if (value.EqualsLiteral("left"))
dxNum = leftSpace;
else if (value.EqualsLiteral("right"))
dxNum = width - rightSpace - sizeNum.width;
// see if the denomalign attribute is there
GetAttribute(mContent, mPresentationData.mstyle, nsGkAtoms::denomalign_,
value);
if (value.EqualsLiteral("left"))
dxDen = leftSpace;
else if (value.EqualsLiteral("right"))
dxDen = width - rightSpace - sizeDen.width;
mBoundingMetrics.rightBearing =
NS_MAX(dxNum + bmNum.rightBearing, dxDen + bmDen.rightBearing);
if (mBoundingMetrics.rightBearing < width - rightSpace)
mBoundingMetrics.rightBearing = width - rightSpace;
mBoundingMetrics.leftBearing =
NS_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.ascent = sizeNum.ascent + numShift;
aDesiredSize.height = aDesiredSize.ascent +
sizeDen.height - sizeDen.ascent + denShift;
aDesiredSize.width = mBoundingMetrics.width;
aDesiredSize.mBoundingMetrics = mBoundingMetrics;
mReference.x = 0;
mReference.y = aDesiredSize.ascent;
if (aPlaceOrigin) {
nscoord dy;
// place numerator
dy = 0;
FinishReflowChild(frameNum, presContext, nsnull, sizeNum, dxNum, dy, 0);
// place denominator
dy = aDesiredSize.height - sizeDen.height;
FinishReflowChild(frameDen, presContext, nsnull, sizeDen, dxDen, dy, 0);
// place the fraction bar - dy is top of bar
dy = aDesiredSize.ascent - (axisHeight + actualRuleThickness/2);
mLineRect.SetRect(leftSpace, dy, width - (leftSpace + rightSpace), actualRuleThickness);
}
return NS_OK;
}
NS_IMETHODIMP
nsMathMLmfracFrame::AttributeChanged(PRInt32 aNameSpaceID,
nsIAtom* aAttribute,
PRInt32 aModType)
{
if (nsGkAtoms::bevelled_ == aAttribute) {
if (!IsBevelled()) {
// disable the bevelled rendering
if (mSlashChar) {
delete mSlashChar;
mSlashChar = nsnull;
}
}
else {
// enable the bevelled rendering
if (!mSlashChar) {
mSlashChar = new nsMathMLChar();
if (mSlashChar) {
nsPresContext* presContext = PresContext();
nsAutoString slashChar; slashChar.Assign(kSlashChar);
mSlashChar->SetData(presContext, slashChar);
ResolveMathMLCharStyle(presContext, mContent, mStyleContext, mSlashChar, PR_TRUE);
}
}
}
}
return nsMathMLContainerFrame::
AttributeChanged(aNameSpaceID, aAttribute, aModType);
}
NS_IMETHODIMP
nsMathMLmfracFrame::UpdatePresentationDataFromChildAt(PRInt32 aFirstIndex,
PRInt32 aLastIndex,
PRUint32 aFlagsValues,
PRUint32 aFlagsToUpdate)
{
// The REC says "The <mfrac> element sets displaystyle to "false" within
// numerator and denominator"
#if 0
// At one point I thought that it meant that the displaystyle state of
// the numerator and denominator cannot be modified by an ancestor, i.e.,
// to change the displaystlye, one has to use displaystyle="true" with mstyle:
// <mfrac> <mstyle>numerator</mstyle> <mstyle>denominator</mstyle> </mfrac>
// Commenting out for now until it is clear what the intention really is.
// See also the variants for <mover>, <munder>, <munderover>
aFlagsToUpdate &= ~NS_MATHML_DISPLAYSTYLE;
aFlagsValues &= ~NS_MATHML_DISPLAYSTYLE;
#endif
return nsMathMLContainerFrame::
UpdatePresentationDataFromChildAt(aFirstIndex, aLastIndex,
aFlagsValues, aFlagsToUpdate);
}
// ----------------------
// the Style System will use these to pass the proper style context to our MathMLChar
nsStyleContext*
nsMathMLmfracFrame::GetAdditionalStyleContext(PRInt32 aIndex) const
{
if (!mSlashChar) {
return nsnull;
}
switch (aIndex) {
case NS_SLASH_CHAR_STYLE_CONTEXT_INDEX:
return mSlashChar->GetStyleContext();
break;
default:
return nsnull;
}
}
void
nsMathMLmfracFrame::SetAdditionalStyleContext(PRInt32 aIndex,
nsStyleContext* aStyleContext)
{
if (!mSlashChar) {
return;
}
switch (aIndex) {
case NS_SLASH_CHAR_STYLE_CONTEXT_INDEX:
mSlashChar->SetStyleContext(aStyleContext);
break;
}
}