зеркало из https://github.com/mozilla/gecko-dev.git
Rework the positioning functions of <mover>, <munder>, <munderover> to improve their behavior w.r.t italic and non-italics fonts. Also use some fuzzy arithmetic to mitigate roundoff errors that could cause accents to collide with their base, b=135940, r=bzbarsky, sr=roc+moz
This commit is contained in:
rbs%maths.uq.edu.au
Родитель
87c2b9e2b4
Коммит
eba1c08907
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@ -291,6 +291,10 @@ nsMathMLmoverFrame::Place(nsIPresContext* aPresContext,
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GetReflowAndBoundingMetricsFor(baseFrame, baseSize, bmBase);
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GetReflowAndBoundingMetricsFor(overFrame, overSize, bmOver);
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float p2t;
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aPresContext->GetScaledPixelsToTwips(&p2t);
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nscoord onePixel = NSIntPixelsToTwips(1, p2t);
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////////////////////
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// Place Children
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@ -310,11 +314,12 @@ nsMathMLmoverFrame::Place(nsIPresContext* aPresContext,
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// whether we want an accented overscript or not
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nscoord correction = 0;
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GetItalicCorrection (bmBase, correction);
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nscoord delta1 = 0; // gap between base and overscript
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nscoord delta2 = 0; // extra space above overscript
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if (!NS_MATHML_EMBELLISH_IS_ACCENTOVER(mEmbellishData.flags)) {
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// Rule 13a, App. G, TeXbook
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GetItalicCorrection (bmBase, correction);
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nscoord bigOpSpacing1, bigOpSpacing3, bigOpSpacing5, dummy;
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GetBigOpSpacings (fm,
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bigOpSpacing1, dummy,
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@ -331,7 +336,6 @@ nsMathMLmoverFrame::Place(nsIPresContext* aPresContext,
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}
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else {
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// Rule 12, App. G, TeXbook
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GetSkewCorrectionFromChild (aPresContext, baseFrame, correction);
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// We are going to modify this rule to make it more general.
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// The idea behind Rule 12 in the TeXBook is to keep the accent
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// as close to the base as possible, while ensuring that the
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@ -360,9 +364,9 @@ nsMathMLmoverFrame::Place(nsIPresContext* aPresContext,
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// we try to keep the *bottom* of the accent char atleast x-height
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// from the baseline of the base char. we also slap on an extra
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// padding between the accent and base chars.
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delta1 = ruleThickness; // we have atleast the padding
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delta1 = ruleThickness + onePixel/2; // we have at least the padding
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if (bmBase.ascent < xHeight) {
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// also ensure atleast x-height above the baseline of the base
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// also ensure at least x-height above the baseline of the base
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delta1 += xHeight - bmBase.ascent;
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}
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delta2 = ruleThickness;
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@ -370,13 +374,7 @@ nsMathMLmoverFrame::Place(nsIPresContext* aPresContext,
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// empty over?
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if (!(bmOver.ascent + bmOver.descent)) delta1 = 0;
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mBoundingMetrics.ascent =
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bmOver.ascent + bmOver.descent + delta1 + bmBase.ascent;
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mBoundingMetrics.descent = bmBase.descent;
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nscoord dxBase, dxOver = 0;
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nscoord dyBase, dyOver;
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// Ad-hoc - This is to override fonts which have ready-made _accent_
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// glyphs with negative lbearing and rbearing. We want to position
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@ -388,13 +386,22 @@ nsMathMLmoverFrame::Place(nsIPresContext* aPresContext,
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}
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if (NS_MATHML_EMBELLISH_IS_ACCENTOVER(mEmbellishData.flags)) {
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mBoundingMetrics.width = PR_MAX(bmBase.width, overWidth);
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mBoundingMetrics.width = bmBase.width;
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dxOver += correction + (mBoundingMetrics.width - overWidth)/2;
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}
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else {
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mBoundingMetrics.width =
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PR_MAX(bmBase.width/2,(overWidth + correction/2)/2) +
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PR_MAX(bmBase.width/2,(overWidth - correction/2)/2);
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mBoundingMetrics.width = PR_MAX(bmBase.width, overWidth);
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dxOver += correction/2 + (mBoundingMetrics.width - overWidth)/2;
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}
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dxBase = (mBoundingMetrics.width - bmBase.width) / 2;
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mBoundingMetrics.ascent =
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bmOver.ascent + bmOver.descent + delta1 + bmBase.ascent;
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mBoundingMetrics.descent = bmBase.descent;
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mBoundingMetrics.leftBearing =
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PR_MIN(dxBase + bmBase.leftBearing, dxOver + bmOver.leftBearing);
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mBoundingMetrics.rightBearing =
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PR_MAX(dxBase + bmBase.rightBearing, dxOver + bmOver.rightBearing);
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aDesiredSize.descent = baseSize.descent;
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aDesiredSize.ascent =
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@ -402,34 +409,19 @@ nsMathMLmoverFrame::Place(nsIPresContext* aPresContext,
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overSize.ascent + bmOver.descent + delta1 + bmBase.ascent);
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aDesiredSize.height = aDesiredSize.ascent + aDesiredSize.descent;
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aDesiredSize.width = mBoundingMetrics.width;
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dxBase = (mBoundingMetrics.width - bmBase.width) / 2;
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dyBase = aDesiredSize.ascent - baseSize.ascent;
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if (NS_MATHML_EMBELLISH_IS_ACCENTOVER(mEmbellishData.flags)) {
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dxOver += correction + (mBoundingMetrics.width - overWidth)/2;
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}
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else {
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dxOver += correction/2 + (mBoundingMetrics.width - overWidth)/2;
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}
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dyOver = aDesiredSize.ascent -
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mBoundingMetrics.ascent + bmOver.ascent - overSize.ascent;
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aDesiredSize.mBoundingMetrics = mBoundingMetrics;
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mReference.x = 0;
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mReference.y = aDesiredSize.ascent;
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mBoundingMetrics.leftBearing =
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PR_MIN(dxBase + bmBase.leftBearing, dxOver + bmOver.leftBearing);
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mBoundingMetrics.rightBearing =
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PR_MAX(dxBase + bmBase.rightBearing, dxOver + bmOver.rightBearing);
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aDesiredSize.mBoundingMetrics = mBoundingMetrics;
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if (aPlaceOrigin) {
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// place base
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FinishReflowChild (baseFrame, aPresContext, nsnull, baseSize, dxBase, dyBase, 0);
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nscoord dy = aDesiredSize.ascent - baseSize.ascent;
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FinishReflowChild (baseFrame, aPresContext, nsnull, baseSize, dxBase, dy, 0);
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// place overscript
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FinishReflowChild (overFrame, aPresContext, nsnull, overSize, dxOver, dyOver, 0);
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dy = aDesiredSize.ascent -
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mBoundingMetrics.ascent + bmOver.ascent - overSize.ascent;
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FinishReflowChild (overFrame, aPresContext, nsnull, overSize, dxOver, dy, 0);
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}
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return NS_OK;
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}
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@ -288,6 +288,10 @@ nsMathMLmunderFrame::Place(nsIPresContext* aPresContext,
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GetReflowAndBoundingMetricsFor(baseFrame, baseSize, bmBase);
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GetReflowAndBoundingMetricsFor(underFrame, underSize, bmUnder);
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float p2t;
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aPresContext->GetScaledPixelsToTwips(&p2t);
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nscoord onePixel = NSIntPixelsToTwips(1, p2t);
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////////////////////
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// Place Children
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@ -306,12 +310,13 @@ nsMathMLmunderFrame::Place(nsIPresContext* aPresContext,
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// there are 2 different types of placement depending on
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// whether we want an accented under or not
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nscoord italicCorrection = 0;
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nscoord correction = 0;
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GetItalicCorrection (bmBase, correction);
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nscoord delta1 = 0; // gap between base and underscript
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nscoord delta2 = 0; // extra space beneath underscript
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if (!NS_MATHML_EMBELLISH_IS_ACCENTUNDER(mEmbellishData.flags)) {
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// Rule 13a, App. G, TeXbook
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GetItalicCorrection (bmBase, italicCorrection);
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nscoord bigOpSpacing2, bigOpSpacing4, bigOpSpacing5, dummy;
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GetBigOpSpacings (fm,
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dummy, bigOpSpacing2,
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@ -325,22 +330,27 @@ nsMathMLmunderFrame::Place(nsIPresContext* aPresContext,
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// XXX tune the gap delta between base and underscript
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// Should we use Rule 10 like \underline does?
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delta1 = ruleThickness;
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delta1 = ruleThickness + onePixel/2;
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delta2 = ruleThickness;
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}
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// empty under?
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if (!(bmUnder.ascent + bmUnder.descent)) delta1 = 0;
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nscoord dxBase, dxUnder;
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nscoord maxWidth = PR_MAX(bmBase.width, bmUnder.width);
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if (NS_MATHML_EMBELLISH_IS_ACCENTUNDER(mEmbellishData.flags)) {
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dxUnder = (maxWidth - bmUnder.width)/2;
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}
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else {
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dxUnder = -correction/2 + (maxWidth - bmUnder.width)/2;
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}
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dxBase = (maxWidth - bmBase.width)/2;
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mBoundingMetrics.width =
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PR_MAX(dxBase + bmBase.width, dxUnder + bmUnder.width);
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mBoundingMetrics.ascent = bmBase.ascent;
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mBoundingMetrics.descent =
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bmBase.descent + delta1 + bmUnder.ascent + bmUnder.descent;
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mBoundingMetrics.width =
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PR_MAX(bmBase.width/2,(bmUnder.width + italicCorrection/2)/2) +
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PR_MAX(bmBase.width/2,(bmUnder.width - italicCorrection/2)/2);
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nscoord dxBase = (mBoundingMetrics.width - bmBase.width) / 2;
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nscoord dxUnder = (mBoundingMetrics.width - (bmUnder.width + italicCorrection/2)) / 2;
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mBoundingMetrics.leftBearing =
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PR_MIN(dxBase + bmBase.leftBearing, dxUnder + bmUnder.leftBearing);
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mBoundingMetrics.rightBearing =
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@ -351,9 +361,7 @@ nsMathMLmunderFrame::Place(nsIPresContext* aPresContext,
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PR_MAX(mBoundingMetrics.descent + delta2,
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bmBase.descent + delta1 + bmUnder.ascent + underSize.descent);
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aDesiredSize.height = aDesiredSize.ascent + aDesiredSize.descent;
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aDesiredSize.width =
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PR_MAX(baseSize.width/2,(underSize.width + italicCorrection/2)/2) +
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PR_MAX(baseSize.width/2,(underSize.width - italicCorrection/2)/2);
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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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@ -331,6 +331,10 @@ nsMathMLmunderoverFrame::Place(nsIPresContext* aPresContext,
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GetReflowAndBoundingMetricsFor(underFrame, underSize, bmUnder);
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GetReflowAndBoundingMetricsFor(overFrame, overSize, bmOver);
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float p2t;
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aPresContext->GetScaledPixelsToTwips(&p2t);
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nscoord onePixel = NSIntPixelsToTwips(1, p2t);
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////////////////////
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// Place Children
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@ -346,16 +350,17 @@ nsMathMLmunderoverFrame::Place(nsIPresContext* aPresContext,
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nscoord ruleThickness;
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GetRuleThickness (aRenderingContext, fm, ruleThickness);
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nscoord correction = 0;
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GetItalicCorrection (bmBase, correction);
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// there are 2 different types of placement depending on
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// whether we want an accented under or not
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nscoord italicCorrection = 0;
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nscoord underDelta1 = 0; // gap between base and underscript
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nscoord underDelta2 = 0; // extra space beneath underscript
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if (!NS_MATHML_EMBELLISH_IS_ACCENTUNDER(mEmbellishData.flags)) {
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// Rule 13a, App. G, TeXbook
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GetItalicCorrection (bmBase, italicCorrection);
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nscoord bigOpSpacing2, bigOpSpacing4, bigOpSpacing5, dummy;
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GetBigOpSpacings (fm,
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dummy, bigOpSpacing2,
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@ -369,19 +374,17 @@ nsMathMLmunderoverFrame::Place(nsIPresContext* aPresContext,
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// XXX tune the gap delta between base and underscript
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// Should we use Rule 10 like \underline does?
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underDelta1 = ruleThickness;
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underDelta1 = ruleThickness + onePixel/2;
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underDelta2 = ruleThickness;
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}
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// empty under?
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if (!(bmUnder.ascent + bmUnder.descent)) underDelta1 = 0;
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nscoord correction = 0;
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nscoord overDelta1 = 0; // gap between base and overscript
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nscoord overDelta2 = 0; // extra space above overscript
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if (!NS_MATHML_EMBELLISH_IS_ACCENTOVER(mEmbellishData.flags)) {
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// Rule 13a, App. G, TeXbook
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GetItalicCorrection (bmBase, italicCorrection);
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nscoord bigOpSpacing1, bigOpSpacing3, bigOpSpacing5, dummy;
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GetBigOpSpacings (fm,
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bigOpSpacing1, dummy,
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@ -397,9 +400,8 @@ nsMathMLmunderoverFrame::Place(nsIPresContext* aPresContext,
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overDelta1 = PR_MAX(bigOpSpacing1, (bigOpSpacing3 - (bmOver.ascent + bmOver.descent)));
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}
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else {
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// Rule 13, App. G, TeXbook
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GetSkewCorrectionFromChild (aPresContext, baseFrame, correction);
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overDelta1 = ruleThickness;
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// Rule 12, App. G, TeXbook
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overDelta1 = ruleThickness + onePixel/2;
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if (bmBase.ascent < xHeight) {
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overDelta1 += xHeight - bmBase.ascent;
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}
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@ -408,33 +410,78 @@ nsMathMLmunderoverFrame::Place(nsIPresContext* aPresContext,
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// empty over?
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if (!(bmOver.ascent + bmOver.descent)) overDelta1 = 0;
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nscoord dxBase, dxOver = 0, dxUnder = 0;
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//////////
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// pass 1, do what <mover> does: attach the overscript on the base
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// Ad-hoc - This is to override fonts which have ready-made _accent_
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// glyphs with negative lbearing and rbearing. We want to position
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// the overscript ourselves
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nscoord overWidth = bmOver.width;
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if (!overWidth && (bmOver.rightBearing - bmOver.leftBearing > 0)) {
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overWidth = bmOver.rightBearing - bmOver.leftBearing;
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dxOver = -bmOver.leftBearing;
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}
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if (NS_MATHML_EMBELLISH_IS_ACCENTOVER(mEmbellishData.flags)) {
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mBoundingMetrics.width = bmBase.width;
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dxOver += correction + (mBoundingMetrics.width - overWidth)/2;
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}
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else {
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mBoundingMetrics.width = PR_MAX(bmBase.width, overWidth);
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dxOver += correction/2 + (mBoundingMetrics.width - overWidth)/2;
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}
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dxBase = (mBoundingMetrics.width - bmBase.width)/2;
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mBoundingMetrics.ascent =
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bmBase.ascent + overDelta1 + bmOver.ascent + bmOver.descent;
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mBoundingMetrics.descent =
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bmBase.descent + underDelta1 + bmUnder.ascent + bmUnder.descent;
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mBoundingMetrics.width =
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PR_MAX(bmBase.width/2,PR_MAX((bmUnder.width + italicCorrection/2)/2,(bmOver.width - correction/2)/2)) +
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PR_MAX(bmBase.width/2,PR_MAX((bmUnder.width - italicCorrection/2)/2,(bmOver.width + correction/2)/2));
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nscoord dxBase = (mBoundingMetrics.width - bmBase.width) / 2;
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nscoord dxOver = (mBoundingMetrics.width - (bmOver.width - correction/2)) / 2;
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nscoord dxUnder = (mBoundingMetrics.width - (bmUnder.width + italicCorrection/2)) / 2;
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mBoundingMetrics.leftBearing =
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PR_MIN(dxBase + bmBase.leftBearing, dxUnder + bmUnder.leftBearing);
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PR_MIN(dxBase + bmBase.leftBearing, dxOver + bmOver.leftBearing);
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mBoundingMetrics.rightBearing =
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PR_MAX(dxBase + bmBase.rightBearing, dxUnder + bmUnder.rightBearing);
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mBoundingMetrics.leftBearing =
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PR_MIN(mBoundingMetrics.leftBearing, dxOver + bmOver.leftBearing);
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mBoundingMetrics.rightBearing =
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PR_MAX(mBoundingMetrics.rightBearing, dxOver + bmOver.rightBearing);
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PR_MAX(dxBase + bmBase.rightBearing, dxOver + bmOver.rightBearing);
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aDesiredSize.ascent =
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//////////
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// pass 2, do what <munder> does: attach the underscript on the previous
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// result. We conceptually view the previous result as an "anynomous base"
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// from where to attach the underscript. Hence if the underscript is empty,
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// we should end up like <mover>. If the overscript is empty, we should
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// end up like <munder>.
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nsBoundingMetrics bmAnonymousBase = mBoundingMetrics;
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nscoord ascentAnonymousBase =
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PR_MAX(mBoundingMetrics.ascent + overDelta2,
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overSize.ascent + bmOver.descent + overDelta1 + bmBase.ascent);
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GetItalicCorrection(bmAnonymousBase, correction);
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nscoord maxWidth = PR_MAX(bmAnonymousBase.width, bmUnder.width);
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if (NS_MATHML_EMBELLISH_IS_ACCENTUNDER(mEmbellishData.flags)) {
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dxUnder = (maxWidth - bmUnder.width)/2;;
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}
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else {
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dxUnder = -correction/2 + (maxWidth - bmUnder.width)/2;
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}
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nscoord dxAnonymousBase = (maxWidth - bmAnonymousBase.width)/2;
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// adjust the offsets of the real base and overscript since their
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// final offsets should be relative to us...
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dxOver += dxAnonymousBase;
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dxBase += dxAnonymousBase;
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mBoundingMetrics.width =
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PR_MAX(dxAnonymousBase + bmAnonymousBase.width, dxUnder + bmUnder.width);
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mBoundingMetrics.leftBearing =
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PR_MIN(dxAnonymousBase + bmAnonymousBase.leftBearing, dxUnder + bmUnder.leftBearing);
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mBoundingMetrics.rightBearing =
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PR_MAX(dxAnonymousBase + bmAnonymousBase.rightBearing, dxUnder + bmUnder.rightBearing);
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aDesiredSize.ascent = ascentAnonymousBase;
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aDesiredSize.descent =
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PR_MAX(mBoundingMetrics.descent + underDelta2,
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bmBase.descent + underDelta1 + bmUnder.ascent + underSize.descent);
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bmAnonymousBase.descent + underDelta1 + bmUnder.ascent + underSize.descent);
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aDesiredSize.height = aDesiredSize.ascent + aDesiredSize.descent;
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aDesiredSize.width = mBoundingMetrics.width;
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aDesiredSize.mBoundingMetrics = mBoundingMetrics;
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