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gecko-dev/layout/mathml/nsMathMLmfracFrame.cpp
L. David Baron d2b6891283 Switch lots of callers to using nsLayoutUtils::GetFontMetricsForFrame and nsLayoutUtils::GetFontMetricsForStyleContext. (Bug 678671, patch 1) r=roc 
This changes a number of callers that were previously bypassing the use
of the correct language (with either no language or the charset-detected
language on the pres context via nsPresContext::GetMetricsFor) and/or
the correct user font set to pass the correct values, which should
improve the correctness of the behavior of whatever they were using the
fonts for, and also reduce the number of unique sets of font metrics
requested (which helps nsFontCache effectiveness).
2011-08-14 10:08:04 -07:00

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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>
* Frederic Wang <fred.wang@free.fr>
* Florian Scholz <elchi3@elchi3.de>
*
* 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 "nsRenderingContext.h"
#include "nsMathMLmfracFrame.h"
#include "nsDisplayList.h"
#include "gfxContext.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 THICK_FRACTION_LINE 2.0f
#define THICK_FRACTION_LINE_MINIMUM_PIXELS 2 // minimum of 2 pixels
nsIFrame*
NS_NewMathMLmfracFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)
{
return new (aPresShell) nsMathMLmfracFrame(aContext);
}
NS_IMPL_FRAMEARENA_HELPERS(nsMathMLmfracFrame)
nsMathMLmfracFrame::~nsMathMLmfracFrame()
{
}
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")) {
// medium is default
}
else if (aThicknessAttribute.EqualsLiteral("thick")) {
lineThickness = NSToCoordCeil(defaultThickness * THICK_FRACTION_LINE);
minimumThickness = onePixel * THICK_FRACTION_LINE_MINIMUM_PIXELS;
// should visually increase by at least one pixel
if (lineThickness < defaultThickness + onePixel)
lineThickness = defaultThickness + 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 (mIsBevelled) {
rv = DisplaySlash(aBuilder, this, mLineRect, mLineThickness, aLists);
} else {
rv = DisplayBar(aBuilder, this, mLineRect, aLists);
}
return rv;
}
/* virtual */ nsresult
nsMathMLmfracFrame::MeasureForWidth(nsRenderingContext& aRenderingContext,
nsHTMLReflowMetrics& aDesiredSize)
{
return PlaceInternal(aRenderingContext,
PR_FALSE,
aDesiredSize,
PR_TRUE);
}
nscoord
nsMathMLmfracFrame::FixInterFrameSpacing(nsHTMLReflowMetrics& aDesiredSize)
{
nscoord gap = nsMathMLContainerFrame::FixInterFrameSpacing(aDesiredSize);
if (!gap) return 0;
mLineRect.MoveBy(gap, 0);
return gap;
}
/* virtual */ nsresult
nsMathMLmfracFrame::Place(nsRenderingContext& aRenderingContext,
PRBool aPlaceOrigin,
nsHTMLReflowMetrics& aDesiredSize)
{
return PlaceInternal(aRenderingContext,
aPlaceOrigin,
aDesiredSize,
PR_FALSE);
}
nsresult
nsMathMLmfracFrame::PlaceInternal(nsRenderingContext& aRenderingContext,
PRBool aPlaceOrigin,
nsHTMLReflowMetrics& aDesiredSize,
PRBool aWidthOnly)
{
////////////////////////////////////
// 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);
nsPresContext* presContext = PresContext();
nscoord onePixel = nsPresContext::CSSPixelsToAppUnits(1);
nsRefPtr<nsFontMetrics> fm;
nsLayoutUtils::GetFontMetricsForFrame(this, getter_AddRefs(fm));
aRenderingContext.SetFont(fm);
nscoord defaultRuleThickness, axisHeight;
GetRuleThickness(aRenderingContext, fm, defaultRuleThickness);
GetAxisHeight(aRenderingContext, fm, axisHeight);
nsEmbellishData coreData;
GetEmbellishDataFrom(mEmbellishData.coreFrame, coreData);
// see if the linethickness attribute is there
nsAutoString value;
GetAttribute(mContent, mPresentationData.mstyle, nsGkAtoms::linethickness_,
value);
mLineThickness = CalcLineThickness(presContext, mStyleContext, value,
onePixel, defaultRuleThickness);
// bevelled attribute
GetAttribute(mContent, mPresentationData.mstyle, nsGkAtoms::bevelled_,
value);
mIsBevelled = value.EqualsLiteral("true");
if (!mIsBevelled) {
mLineRect.height = mLineThickness;
// 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)
nscoord leftSpace = NS_MAX(onePixel, coreData.leftSpace);
nscoord rightSpace = NS_MAX(onePixel, coreData.rightSpace);
//////////////////
// 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 (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 = mLineThickness;
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);
}
} else {
nscoord numShift = 0.0;
nscoord denShift = 0.0;
nscoord padding = 3 * defaultRuleThickness;
nscoord slashRatio = 3;
// Define the constant used in the expression of the maximum width
nscoord em = fm->EmHeight();
nscoord slashMaxWidthConstant = 2 * em;
// For large line thicknesses the minimum slash height is limited to the
// largest expected height of a fraction
nscoord slashMinHeight = slashRatio *
NS_MIN(2 * mLineThickness, slashMaxWidthConstant);
nscoord leftSpace = NS_MAX(padding, coreData.leftSpace);
nscoord rightSpace = NS_MAX(padding, coreData.rightSpace);
nscoord delta;
// ___________
// | | /
// {|-NUMERATOR-| /
// {|___________| S
// { L
// numShift{ A
// ------------------------------------------------------- baseline
// S _____________ } denShift
// H | |}
// / |-DENOMINATOR-|}
// / |_____________|
//
// first, ensure that the top of the numerator is at least as high as the
// top of the denominator (and the reverse for the bottoms)
delta = NS_MAX(bmDen.ascent - bmNum.ascent,
bmNum.descent - bmDen.descent) / 2;
if (delta > 0) {
numShift += delta;
denShift += delta;
}
if (NS_MATHML_IS_DISPLAYSTYLE(mPresentationData.flags)) {
delta = NS_MIN(bmDen.ascent + bmDen.descent,
bmNum.ascent + bmNum.descent) / 2;
numShift += delta;
denShift += delta;
} else {
nscoord xHeight = fm->XHeight();
numShift += xHeight / 2;
denShift += xHeight / 4;
}
// Set the ascent/descent of our BoundingMetrics.
mBoundingMetrics.ascent = bmNum.ascent + numShift;
mBoundingMetrics.descent = bmDen.descent + denShift;
// At this point the height of the slash is
// mBoundingMetrics.ascent + mBoundingMetrics.descent
// Ensure that it is greater than slashMinHeight
delta = (slashMinHeight -
(mBoundingMetrics.ascent + mBoundingMetrics.descent)) / 2;
if (delta > 0) {
mBoundingMetrics.ascent += delta;
mBoundingMetrics.descent += delta;
}
// Set the width of the slash
if (aWidthOnly) {
mLineRect.width = mLineThickness + slashMaxWidthConstant;
} else {
mLineRect.width = mLineThickness +
NS_MIN(slashMaxWidthConstant,
(mBoundingMetrics.ascent + mBoundingMetrics.descent) /
slashRatio);
}
// Set horizontal bounding metrics
mBoundingMetrics.leftBearing = leftSpace + bmNum.leftBearing;
mBoundingMetrics.rightBearing =
leftSpace + bmNum.width + mLineRect.width + bmDen.rightBearing;
mBoundingMetrics.width =
leftSpace + bmNum.width + mLineRect.width + bmDen.width + rightSpace;
// Set aDesiredSize
aDesiredSize.ascent = mBoundingMetrics.ascent + padding;
aDesiredSize.height =
mBoundingMetrics.ascent + mBoundingMetrics.descent + 2 * padding;
aDesiredSize.width = mBoundingMetrics.width;
aDesiredSize.mBoundingMetrics = mBoundingMetrics;
mReference.x = 0;
mReference.y = aDesiredSize.ascent;
if (aPlaceOrigin) {
FinishReflowChild(frameNum, presContext, nsnull, sizeNum,
leftSpace,
aDesiredSize.ascent - numShift - sizeNum.ascent, 0);
mLineRect.SetRect(leftSpace + bmNum.width,
aDesiredSize.ascent - mBoundingMetrics.ascent,
mLineRect.width,
aDesiredSize.height - 2 * padding);
FinishReflowChild(frameDen, presContext, nsnull, sizeDen,
leftSpace + bmNum.width + mLineRect.width,
aDesiredSize.ascent + denShift - sizeDen.ascent, 0);
}
}
return NS_OK;
}
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 displaystyle, 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);
}
class nsDisplayMathMLSlash : public nsDisplayItem {
public:
nsDisplayMathMLSlash(nsDisplayListBuilder* aBuilder,
nsIFrame* aFrame, const nsRect& aRect,
nscoord aThickness)
: nsDisplayItem(aBuilder, aFrame), mRect(aRect), mThickness(aThickness) {
MOZ_COUNT_CTOR(nsDisplayMathMLSlash);
}
#ifdef NS_BUILD_REFCNT_LOGGING
virtual ~nsDisplayMathMLSlash() {
MOZ_COUNT_DTOR(nsDisplayMathMLSlash);
}
#endif
virtual void Paint(nsDisplayListBuilder* aBuilder, nsRenderingContext* aCtx);
NS_DISPLAY_DECL_NAME("MathMLSlash", TYPE_MATHML_SLASH)
private:
nsRect mRect;
nscoord mThickness;
};
void nsDisplayMathMLSlash::Paint(nsDisplayListBuilder* aBuilder,
nsRenderingContext* aCtx)
{
// get the gfxRect
nsPresContext* presContext = mFrame->PresContext();
gfxRect rect = presContext->AppUnitsToGfxUnits(mRect + ToReferenceFrame());
// paint with the current text color
aCtx->SetColor(mFrame->GetStyleColor()->mColor);
// draw the slash as a parallelogram
gfxContext *gfxCtx = aCtx->ThebesContext();
gfxPoint delta = gfxPoint(presContext->AppUnitsToGfxUnits(mThickness), 0);
gfxCtx->NewPath();
gfxCtx->MoveTo(rect.BottomLeft());
gfxCtx->LineTo(rect.BottomLeft() + delta);
gfxCtx->LineTo(rect.TopRight());
gfxCtx->LineTo(rect.TopRight() - delta);
gfxCtx->ClosePath();
gfxCtx->Fill();
}
nsresult
nsMathMLmfracFrame::DisplaySlash(nsDisplayListBuilder* aBuilder,
nsIFrame* aFrame, const nsRect& aRect,
nscoord aThickness,
const nsDisplayListSet& aLists) {
if (!aFrame->GetStyleVisibility()->IsVisible() || aRect.IsEmpty())
return NS_OK;
return aLists.Content()->AppendNewToTop(new (aBuilder)
nsDisplayMathMLSlash(aBuilder, aFrame, aRect, aThickness));
}
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