Exemple #1
0
void
nsTextBoxFrame::GetTextSize(nsPresContext* aPresContext, nsIRenderingContext& aRenderingContext,
                                const nsString& aString, nsSize& aSize, nscoord& aAscent)
{
    nsCOMPtr<nsIFontMetrics> fontMet;
    nsLayoutUtils::GetFontMetricsForFrame(this, getter_AddRefs(fontMet));
    fontMet->GetHeight(aSize.height);
    aRenderingContext.SetFont(fontMet);
    aSize.width =
      nsLayoutUtils::GetStringWidth(this, &aRenderingContext, aString.get(), aString.Length());
    fontMet->GetMaxAscent(aAscent);
}
void
nsPageFrame::PaintHeaderFooter(nsIRenderingContext& aRenderingContext,
                               nsPoint aPt)
{
  nsPresContext* pc = PresContext();

  if (!mPD->mPrintSettings) {
    if (pc->Type() == nsPresContext::eContext_PrintPreview || pc->IsDynamic())
      mPD->mPrintSettings = pc->GetPrintSettings();
    if (!mPD->mPrintSettings)
      return;
  }

  nsRect rect(aPt.x, aPt.y, mRect.width - mPD->mShadowSize.width,
              mRect.height - mPD->mShadowSize.height);

  aRenderingContext.SetColor(NS_RGB(0,0,0));

  // Get the FontMetrics to determine width.height of strings
  nsCOMPtr<nsIFontMetrics> fontMet;
  pc->DeviceContext()->GetMetricsFor(*mPD->mHeadFootFont,
                                     pc->GetUserFontSet(),
                                     *getter_AddRefs(fontMet));

  aRenderingContext.SetFont(fontMet);

  nscoord ascent = 0;
  nscoord visibleHeight = 0;
  if (fontMet) {
    fontMet->GetHeight(visibleHeight);
    fontMet->GetMaxAscent(ascent);
  }

  // print document headers and footers
  nsXPIDLString headerLeft, headerCenter, headerRight;
  mPD->mPrintSettings->GetHeaderStrLeft(getter_Copies(headerLeft));
  mPD->mPrintSettings->GetHeaderStrCenter(getter_Copies(headerCenter));
  mPD->mPrintSettings->GetHeaderStrRight(getter_Copies(headerRight));
  DrawHeaderFooter(aRenderingContext, eHeader,
                   headerLeft, headerCenter, headerRight,
                   rect, ascent, visibleHeight);

  nsXPIDLString footerLeft, footerCenter, footerRight;
  mPD->mPrintSettings->GetFooterStrLeft(getter_Copies(footerLeft));
  mPD->mPrintSettings->GetFooterStrCenter(getter_Copies(footerCenter));
  mPD->mPrintSettings->GetFooterStrRight(getter_Copies(footerRight));
  DrawHeaderFooter(aRenderingContext, eFooter,
                   footerLeft, footerCenter, footerRight,
                   rect, ascent, visibleHeight);
}
NS_IMETHODIMP
nsMathMLmunderoverFrame::Place(nsIRenderingContext& aRenderingContext,
                               PRBool               aPlaceOrigin,
                               nsHTMLReflowMetrics& aDesiredSize)
{
  if ( NS_MATHML_EMBELLISH_IS_MOVABLELIMITS(mEmbellishData.flags) &&
      !NS_MATHML_IS_DISPLAYSTYLE(mPresentationData.flags)) {
    // place like sub-superscript pair
    return nsMathMLmsubsupFrame::PlaceSubSupScript(GetPresContext(),
                                                   aRenderingContext,
                                                   aPlaceOrigin,
                                                   aDesiredSize,
                                                   this);
  }

  ////////////////////////////////////
  // Get the children's desired sizes

  nsBoundingMetrics bmBase, bmUnder, bmOver;
  nsHTMLReflowMetrics baseSize (nsnull);
  nsHTMLReflowMetrics underSize (nsnull);
  nsHTMLReflowMetrics overSize (nsnull);
  nsIFrame* overFrame = nsnull;
  nsIFrame* underFrame = nsnull;
  nsIFrame* baseFrame = mFrames.FirstChild();
  if (baseFrame)
    underFrame = baseFrame->GetNextSibling();
  if (underFrame)
    overFrame = underFrame->GetNextSibling();
  if (!baseFrame || !underFrame || !overFrame || overFrame->GetNextSibling()) {
    // report an error, encourage people to get their markups in order
    NS_WARNING("invalid markup");
    return ReflowError(aRenderingContext, aDesiredSize);
  }
  GetReflowAndBoundingMetricsFor(baseFrame, baseSize, bmBase);
  GetReflowAndBoundingMetricsFor(underFrame, underSize, bmUnder);
  GetReflowAndBoundingMetricsFor(overFrame, overSize, bmOver);

  nscoord onePixel = GetPresContext()->IntScaledPixelsToTwips(1);

  ////////////////////
  // Place Children

  aRenderingContext.SetFont(GetStyleFont()->mFont, nsnull);
  nsCOMPtr<nsIFontMetrics> fm;
  aRenderingContext.GetFontMetrics(*getter_AddRefs(fm));

  nscoord xHeight = 0;
  fm->GetXHeight (xHeight);

  nscoord ruleThickness;
  GetRuleThickness (aRenderingContext, fm, ruleThickness);

  nscoord correction = 0;
  GetItalicCorrection (bmBase, correction);

  // there are 2 different types of placement depending on 
  // whether we want an accented under or not

  nscoord underDelta1 = 0; // gap between base and underscript
  nscoord underDelta2 = 0; // extra space beneath underscript

  if (!NS_MATHML_EMBELLISH_IS_ACCENTUNDER(mEmbellishData.flags)) {
    // Rule 13a, App. G, TeXbook
    nscoord bigOpSpacing2, bigOpSpacing4, bigOpSpacing5, dummy; 
    GetBigOpSpacings (fm, 
                      dummy, bigOpSpacing2, 
                      dummy, bigOpSpacing4, 
                      bigOpSpacing5);
    underDelta1 = PR_MAX(bigOpSpacing2, (bigOpSpacing4 - bmUnder.ascent));
    underDelta2 = bigOpSpacing5;
  }
  else {
    // No corresponding rule in TeXbook - we are on our own here
    // XXX tune the gap delta between base and underscript 

    // Should we use Rule 10 like \underline does?
    underDelta1 = ruleThickness + onePixel/2;
    underDelta2 = ruleThickness;
  }
  // empty under?
  if (!(bmUnder.ascent + bmUnder.descent)) underDelta1 = 0;

  nscoord overDelta1 = 0; // gap between base and overscript
  nscoord overDelta2 = 0; // extra space above overscript

  if (!NS_MATHML_EMBELLISH_IS_ACCENTOVER(mEmbellishData.flags)) {    
    // Rule 13a, App. G, TeXbook
    nscoord bigOpSpacing1, bigOpSpacing3, bigOpSpacing5, dummy; 
    GetBigOpSpacings (fm, 
                      bigOpSpacing1, dummy, 
                      bigOpSpacing3, dummy, 
                      bigOpSpacing5);
    overDelta1 = PR_MAX(bigOpSpacing1, (bigOpSpacing3 - bmOver.descent));
    overDelta2 = bigOpSpacing5;

    // XXX This is not a TeX rule... 
    // delta1 (as computed abvove) can become really big when bmOver.descent is
    // negative,  e.g., if the content is &OverBar. In such case, we use the height
    if (bmOver.descent < 0)    
      overDelta1 = PR_MAX(bigOpSpacing1, (bigOpSpacing3 - (bmOver.ascent + bmOver.descent)));
  }
  else {
    // Rule 12, App. G, TeXbook
    overDelta1 = ruleThickness + onePixel/2;
    if (bmBase.ascent < xHeight) { 
      overDelta1 += xHeight - bmBase.ascent;
    }
    overDelta2 = ruleThickness;
  }
  // empty over?
  if (!(bmOver.ascent + bmOver.descent)) overDelta1 = 0;

  nscoord dxBase, dxOver = 0, dxUnder = 0;

  //////////
  // pass 1, do what <mover> does: attach the overscript on the base

  // Ad-hoc - This is to override fonts which have ready-made _accent_
  // glyphs with negative lbearing and rbearing. We want to position
  // the overscript ourselves
  nscoord overWidth = bmOver.width;
  if (!overWidth && (bmOver.rightBearing - bmOver.leftBearing > 0)) {
    overWidth = bmOver.rightBearing - bmOver.leftBearing;
    dxOver = -bmOver.leftBearing;
  }

  if (NS_MATHML_EMBELLISH_IS_ACCENTOVER(mEmbellishData.flags)) {
    mBoundingMetrics.width = bmBase.width; 
    dxOver += correction + (mBoundingMetrics.width - overWidth)/2;
  }
  else {
    mBoundingMetrics.width = PR_MAX(bmBase.width, overWidth);
    dxOver += correction/2 + (mBoundingMetrics.width - overWidth)/2;
  }
  dxBase = (mBoundingMetrics.width - bmBase.width)/2;

  mBoundingMetrics.ascent = 
    bmBase.ascent + overDelta1 + bmOver.ascent + bmOver.descent;
  mBoundingMetrics.descent = 
    bmBase.descent + underDelta1 + bmUnder.ascent + bmUnder.descent;
  mBoundingMetrics.leftBearing = 
    PR_MIN(dxBase + bmBase.leftBearing, dxOver + bmOver.leftBearing);
  mBoundingMetrics.rightBearing = 
    PR_MAX(dxBase + bmBase.rightBearing, dxOver + bmOver.rightBearing);

  //////////
  // pass 2, do what <munder> does: attach the underscript on the previous
  // result. We conceptually view the previous result as an "anynomous base" 
  // from where to attach the underscript. Hence if the underscript is empty,
  // we should end up like <mover>. If the overscript is empty, we should
  // end up like <munder>.

  nsBoundingMetrics bmAnonymousBase = mBoundingMetrics;
  nscoord ascentAnonymousBase =
    PR_MAX(mBoundingMetrics.ascent + overDelta2,
           overSize.ascent + bmOver.descent + overDelta1 + bmBase.ascent);

  GetItalicCorrection(bmAnonymousBase, correction);

  nscoord maxWidth = PR_MAX(bmAnonymousBase.width, bmUnder.width);
  if (NS_MATHML_EMBELLISH_IS_ACCENTUNDER(mEmbellishData.flags)) {    
    dxUnder = (maxWidth - bmUnder.width)/2;;
  }
  else {
    dxUnder = -correction/2 + (maxWidth - bmUnder.width)/2;
  }
  nscoord dxAnonymousBase = (maxWidth - bmAnonymousBase.width)/2;

  // adjust the offsets of the real base and overscript since their
  // final offsets should be relative to us...
  dxOver += dxAnonymousBase;
  dxBase += dxAnonymousBase;

  mBoundingMetrics.width =
    PR_MAX(dxAnonymousBase + bmAnonymousBase.width, dxUnder + bmUnder.width);
  mBoundingMetrics.leftBearing =
    PR_MIN(dxAnonymousBase + bmAnonymousBase.leftBearing, dxUnder + bmUnder.leftBearing);
  mBoundingMetrics.rightBearing = 
    PR_MAX(dxAnonymousBase + bmAnonymousBase.rightBearing, dxUnder + bmUnder.rightBearing);

  aDesiredSize.ascent = ascentAnonymousBase;
  aDesiredSize.descent = 
    PR_MAX(mBoundingMetrics.descent + underDelta2,
           bmAnonymousBase.descent + underDelta1 + bmUnder.ascent + underSize.descent);
  aDesiredSize.height = aDesiredSize.ascent + aDesiredSize.descent;
  aDesiredSize.width = mBoundingMetrics.width;
  aDesiredSize.mBoundingMetrics = mBoundingMetrics;

  mReference.x = 0;
  mReference.y = aDesiredSize.ascent;

  if (aPlaceOrigin) {
    nscoord dy;
    // place overscript
    dy = aDesiredSize.ascent - mBoundingMetrics.ascent + bmOver.ascent - overSize.ascent;
    FinishReflowChild (overFrame, GetPresContext(), nsnull, overSize, dxOver, dy, 0);
    // place base
    dy = aDesiredSize.ascent - baseSize.ascent;
    FinishReflowChild (baseFrame, GetPresContext(), nsnull, baseSize, dxBase, dy, 0);
    // place underscript
    dy = aDesiredSize.ascent + mBoundingMetrics.descent - bmUnder.descent - underSize.ascent;
    FinishReflowChild (underFrame, GetPresContext(), nsnull, underSize, dxUnder, dy, 0);
  }
  return NS_OK;
}
/* virtual */ nsresult
nsMathMLmoverFrame::Place(nsIRenderingContext& aRenderingContext,
                          PRBool               aPlaceOrigin,
                          nsHTMLReflowMetrics& aDesiredSize)
{ 
  if ( NS_MATHML_EMBELLISH_IS_MOVABLELIMITS(mEmbellishData.flags) &&
      !NS_MATHML_IS_DISPLAYSTYLE(mPresentationData.flags)) {
    // place like superscript
    return nsMathMLmsupFrame::PlaceSuperScript(PresContext(),
                                               aRenderingContext,
                                               aPlaceOrigin,
                                               aDesiredSize,
                                               this, 0, nsPresContext::CSSPointsToAppUnits(0.5f));
  }

  ////////////////////////////////////
  // Get the children's desired sizes

  nsBoundingMetrics bmBase, bmOver;
  nsHTMLReflowMetrics baseSize;
  nsHTMLReflowMetrics overSize;
  nsIFrame* overFrame = nsnull;
  nsIFrame* baseFrame = mFrames.FirstChild();
  if (baseFrame)
    overFrame = baseFrame->GetNextSibling();
  if (!baseFrame || !overFrame || overFrame->GetNextSibling()) {
    // report an error, encourage people to get their markups in order
    return ReflowError(aRenderingContext, aDesiredSize);
  }
  GetReflowAndBoundingMetricsFor(baseFrame, baseSize, bmBase);
  GetReflowAndBoundingMetricsFor(overFrame, overSize, bmOver);

  nscoord onePixel = nsPresContext::CSSPixelsToAppUnits(1);

  ////////////////////
  // Place Children

  aRenderingContext.SetFont(GetStyleFont()->mFont,
                            PresContext()->GetUserFontSet());
  nsCOMPtr<nsIFontMetrics> fm;
  aRenderingContext.GetFontMetrics(*getter_AddRefs(fm));

  nscoord xHeight = 0;
  fm->GetXHeight (xHeight);

  nscoord ruleThickness;
  GetRuleThickness (aRenderingContext, fm, ruleThickness);

  // there are 2 different types of placement depending on 
  // whether we want an accented overscript or not

  nscoord correction = 0;
  GetItalicCorrection (bmBase, correction);

  nscoord delta1 = 0; // gap between base and overscript
  nscoord delta2 = 0; // extra space above overscript
  if (!NS_MATHML_EMBELLISH_IS_ACCENTOVER(mEmbellishData.flags)) {    
    // Rule 13a, App. G, TeXbook
    nscoord bigOpSpacing1, bigOpSpacing3, bigOpSpacing5, dummy; 
    GetBigOpSpacings (fm, 
                      bigOpSpacing1, dummy, 
                      bigOpSpacing3, dummy, 
                      bigOpSpacing5);
    delta1 = NS_MAX(bigOpSpacing1, (bigOpSpacing3 - bmOver.descent));
    delta2 = bigOpSpacing5;

    // XXX This is not a TeX rule... 
    // delta1 (as computed above) can become really big when bmOver.descent is
    // negative,  e.g., if the content is &OverBar. In such case, we use the height
    if (bmOver.descent < 0)    
      delta1 = NS_MAX(bigOpSpacing1, (bigOpSpacing3 - (bmOver.ascent + bmOver.descent)));
  }
  else {
    // Rule 12, App. G, TeXbook
    // We are going to modify this rule to make it more general.
    // The idea behind Rule 12 in the TeXBook is to keep the accent
    // as close to the base as possible, while ensuring that the
    // distance between the *baseline* of the accent char and 
    // the *baseline* of the base is atleast x-height. 
    // The idea is that for normal use, we would like all the accents
    // on a line to line up atleast x-height above the baseline 
    // if possible. 
    // When the ascent of the base is >= x-height, 
    // the baseline of the accent char is placed just above the base
    // (specifically, the baseline of the accent char is placed 
    // above the baseline of the base by the ascent of the base).
    // For ease of implementation, 
    // this assumes that the font-designer designs accents 
    // in such a way that the bottom of the accent is atleast x-height
    // above its baseline, otherwise there will be collisions
    // with the base. Also there should be proper padding between
    // the bottom of the accent char and its baseline.
    // The above rule may not be obvious from a first
    // reading of rule 12 in the TeXBook !!!
    // The mathml <mover> tag can use accent chars that
    // do not follow this convention. So we modify TeX's rule 
    // so that TeX's rule gets subsumed for accents that follow 
    // TeX's convention,
    // while also allowing accents that do not follow the convention :
    // we try to keep the *bottom* of the accent char atleast x-height 
    // from the baseline of the base char. we also slap on an extra
    // padding between the accent and base chars.
    delta1 = ruleThickness + onePixel/2; // we have at least the padding
    if (bmBase.ascent < xHeight) { 
      // also ensure at least x-height above the baseline of the base
      delta1 += xHeight - bmBase.ascent;
    }
    delta2 = ruleThickness;
  }
  // empty over?
  if (!(bmOver.ascent + bmOver.descent)) delta1 = 0;

  nscoord dxBase, dxOver = 0;

  // Ad-hoc - This is to override fonts which have ready-made _accent_
  // glyphs with negative lbearing and rbearing. We want to position
  // the overscript ourselves
  nscoord overWidth = bmOver.width;
  if (!overWidth && (bmOver.rightBearing - bmOver.leftBearing > 0)) {
    overWidth = bmOver.rightBearing - bmOver.leftBearing;
    dxOver = -bmOver.leftBearing;
  }

  if (NS_MATHML_EMBELLISH_IS_ACCENTOVER(mEmbellishData.flags)) {
    mBoundingMetrics.width = bmBase.width; 
    dxOver += correction + (mBoundingMetrics.width - overWidth)/2;
  }
  else {
    mBoundingMetrics.width = NS_MAX(bmBase.width, overWidth);
    dxOver += correction/2 + (mBoundingMetrics.width - overWidth)/2;
  }
  dxBase = (mBoundingMetrics.width - bmBase.width) / 2;

  mBoundingMetrics.ascent = 
    bmOver.ascent + bmOver.descent + delta1 + bmBase.ascent;
  mBoundingMetrics.descent = bmBase.descent;
  mBoundingMetrics.leftBearing = 
    NS_MIN(dxBase + bmBase.leftBearing, dxOver + bmOver.leftBearing);
  mBoundingMetrics.rightBearing = 
    NS_MAX(dxBase + bmBase.rightBearing, dxOver + bmOver.rightBearing);

  aDesiredSize.ascent = 
    NS_MAX(mBoundingMetrics.ascent + delta2,
           overSize.ascent + bmOver.descent + delta1 + bmBase.ascent);
  aDesiredSize.height = aDesiredSize.ascent +
    baseSize.height - baseSize.ascent;
  aDesiredSize.width = mBoundingMetrics.width;
  aDesiredSize.mBoundingMetrics = mBoundingMetrics;

  mReference.x = 0;
  mReference.y = aDesiredSize.ascent;

  if (aPlaceOrigin) {
    // place base
    nscoord dy = aDesiredSize.ascent - baseSize.ascent;
    FinishReflowChild (baseFrame, PresContext(), nsnull, baseSize, dxBase, dy, 0);
    // place overscript
    dy = aDesiredSize.ascent - 
      mBoundingMetrics.ascent + bmOver.ascent - overSize.ascent;
    FinishReflowChild (overFrame, PresContext(), nsnull, overSize, dxOver, dy, 0);
  }
  return NS_OK;
}
// exported routine that both munderover and msubsup share.
// munderover uses this when movablelimits is set.
nsresult
nsMathMLmsubsupFrame::PlaceSubSupScript(nsPresContext*      aPresContext,
                                        nsIRenderingContext& aRenderingContext,
                                        PRBool               aPlaceOrigin,
                                        nsHTMLReflowMetrics& aDesiredSize,
                                        nsMathMLContainerFrame* aFrame,
                                        nscoord              aUserSubScriptShift,
                                        nscoord              aUserSupScriptShift,
                                        nscoord              aScriptSpace)
{
  // force the scriptSpace to be atleast 1 pixel
  nscoord onePixel = nsPresContext::CSSPixelsToAppUnits(1);
  aScriptSpace = PR_MAX(onePixel, aScriptSpace);

  ////////////////////////////////////
  // Get the children's desired sizes

  nsHTMLReflowMetrics baseSize;
  nsHTMLReflowMetrics subScriptSize;
  nsHTMLReflowMetrics supScriptSize;
  nsBoundingMetrics bmBase, bmSubScript, bmSupScript;
  nsIFrame* subScriptFrame = nsnull;
  nsIFrame* supScriptFrame = nsnull;
  nsIFrame* baseFrame = aFrame->GetFirstChild(nsnull);
  if (baseFrame)
    subScriptFrame = baseFrame->GetNextSibling();
  if (subScriptFrame)
    supScriptFrame = subScriptFrame->GetNextSibling();
  if (!baseFrame || !subScriptFrame || !supScriptFrame ||
      supScriptFrame->GetNextSibling()) {
    // report an error, encourage people to get their markups in order
    return aFrame->ReflowError(aRenderingContext, aDesiredSize);
  }
  GetReflowAndBoundingMetricsFor(baseFrame, baseSize, bmBase);
  GetReflowAndBoundingMetricsFor(subScriptFrame, subScriptSize, bmSubScript);
  GetReflowAndBoundingMetricsFor(supScriptFrame, supScriptSize, bmSupScript);

  // get the subdrop from the subscript font
  nscoord subDrop;
  GetSubDropFromChild(subScriptFrame, subDrop);
  // parameter v, Rule 18a, App. G, TeXbook
  nscoord minSubScriptShift = bmBase.descent + subDrop;

  // get the supdrop from the supscript font
  nscoord supDrop;
  GetSupDropFromChild(supScriptFrame, supDrop);
  // parameter u, Rule 18a, App. G, TeXbook
  nscoord minSupScriptShift = bmBase.ascent - supDrop;

  //////////////////
  // Place Children
  //////////////////

  //////////////////////////////////////////////////
  // Get subscript shift
  // slightly different from nsMathMLmsubFrame.cpp
  //////////////////////////////////////////////////

  // subScriptShift{1,2}
  // = minimum amount to shift the subscript down
  // = sub{1,2} in TeXbook
  // subScriptShift1 = subscriptshift attribute * x-height
  nscoord subScriptShift1, subScriptShift2;

  aRenderingContext.SetFont(baseFrame->GetStyleFont()->mFont, nsnull,
                            aPresContext->GetUserFontSet());
  nsCOMPtr<nsIFontMetrics> fm;
  aRenderingContext.GetFontMetrics(*getter_AddRefs(fm));

  // get x-height (an ex)
  nscoord xHeight;
  fm->GetXHeight (xHeight);

  nscoord ruleSize;
  GetRuleThickness (aRenderingContext, fm, ruleSize);

  // Get subScriptShift{1,2} default from font
  GetSubScriptShifts (fm, subScriptShift1, subScriptShift2);

  if (0 < aUserSubScriptShift) {
    // the user has set the subscriptshift attribute
    float scaler = ((float) subScriptShift2) / subScriptShift1;
    subScriptShift1 = PR_MAX(subScriptShift1, aUserSubScriptShift);
    subScriptShift2 = NSToCoordRound(scaler * subScriptShift1);
  }

  // get a tentative value for subscriptshift
  // Rule 18d, App. G, TeXbook
  nscoord subScriptShift =
    PR_MAX(minSubScriptShift,PR_MAX(subScriptShift1,subScriptShift2));

  //////////////////////////////////////////////////
  // Get supscript shift
  // same code from nsMathMLmsupFrame.cpp
  //////////////////////////////////////////////////

  // get min supscript shift limit from x-height
  // = d(x) + 1/4 * sigma_5, Rule 18c, App. G, TeXbook
  nscoord minShiftFromXHeight = (nscoord)
    (bmSupScript.descent + (1.0f/4.0f) * xHeight);

  // 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);
  if (0 < aUserSupScriptShift) {
    // the user has set the superscriptshift attribute
    float scaler2 = ((float) supScriptShift2) / supScriptShift1;
    float scaler3 = ((float) supScriptShift3) / supScriptShift1;
    supScriptShift1 = PR_MAX(supScriptShift1, aUserSupScriptShift);
    supScriptShift2 = NSToCoordRound(scaler2 * supScriptShift1);
    supScriptShift3 = NSToCoordRound(scaler3 * supScriptShift1);
  }

  // get sup script shift depending on current script level and display style
  // Rule 18c, App. G, TeXbook
  nscoord supScriptShift;
  nsPresentationData presentationData;
  aFrame->GetPresentationData(presentationData);
  if ( aFrame->GetStyleFont()->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;
  }

  // get tentative value for superscriptshift
  // Rule 18c, App. G, TeXbook
  supScriptShift =
    PR_MAX(minSupScriptShift,PR_MAX(supScriptShift,minShiftFromXHeight));

  //////////////////////////////////////////////////
  // Negotiate between supScriptShift and subScriptShift
  // so that there will be enough gap between them
  // Rule 18e, App. G, TeXbook
  //////////////////////////////////////////////////

  nscoord gap =
    (supScriptShift - bmSupScript.descent) -
    (bmSubScript.ascent - subScriptShift);
  if (gap < 4.0f * ruleSize) {
    // adjust subScriptShift to get a gap of (4.0 * ruleSize)
    subScriptShift += 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 -
                        (supScriptShift - bmSupScript.descent));
  if (gap > 0) {
    supScriptShift += gap;
    subScriptShift -= gap;
  }

  //////////////////////////////////////////////////
  // Do the Placing
  //////////////////////////////////////////////////

  // get bounding box for base + subscript + superscript
  nsBoundingMetrics boundingMetrics;
  boundingMetrics.ascent =
    PR_MAX(bmBase.ascent, (bmSupScript.ascent + supScriptShift));
  boundingMetrics.descent =
   PR_MAX(bmBase.descent, (bmSubScript.descent + subScriptShift));

  // leave aScriptSpace after both super/subscript
  // add italicCorrection between base and superscript
  // add "a little to spare" as well (see TeXbook Ch.11, p.64), as we
  // estimate the italic creation ourselves and it isn't the same as TeX 
  nscoord italicCorrection;
  GetItalicCorrection(bmBase, italicCorrection);
  italicCorrection += onePixel;
  boundingMetrics.width = bmBase.width + aScriptSpace +
    PR_MAX((italicCorrection + bmSupScript.width), bmSubScript.width);
  boundingMetrics.leftBearing = bmBase.leftBearing;
  boundingMetrics.rightBearing = bmBase.width +
    PR_MAX((italicCorrection + bmSupScript.rightBearing), bmSubScript.rightBearing);
  aFrame->SetBoundingMetrics(boundingMetrics);

  // reflow metrics
  aDesiredSize.ascent =
    PR_MAX(baseSize.ascent, 
       PR_MAX(subScriptSize.ascent - subScriptShift,
              supScriptSize.ascent + supScriptShift));
  aDesiredSize.height = aDesiredSize.ascent +
    PR_MAX(baseSize.height - baseSize.ascent,
       PR_MAX(subScriptSize.height - subScriptSize.ascent + subScriptShift, 
              supScriptSize.height - subScriptSize.ascent - supScriptShift));
  aDesiredSize.width = boundingMetrics.width;
  aDesiredSize.mBoundingMetrics = boundingMetrics;

  aFrame->SetReference(nsPoint(0, aDesiredSize.ascent));

  if (aPlaceOrigin) {
    nscoord dx, dy;
    // now place the base ...
    dx = 0; dy = aDesiredSize.ascent - baseSize.ascent;
    FinishReflowChild(baseFrame, aPresContext, nsnull,
                      baseSize, dx, dy, 0);
    // ... and subscript
    dx = bmBase.width;
    dy = aDesiredSize.ascent - (subScriptSize.ascent - subScriptShift);
    FinishReflowChild(subScriptFrame, aPresContext, nsnull,
                      subScriptSize, dx, dy, 0);
    // ... and the superscript
    dx = bmBase.width + italicCorrection;
    dy = aDesiredSize.ascent - (supScriptSize.ascent + supScriptShift);
    FinishReflowChild(supScriptFrame, aPresContext, nsnull,
                      supScriptSize, dx, dy, 0);
  }

  return NS_OK;
}
nsresult
nsMathMLmfracFrame::PlaceInternal(nsIRenderingContext& 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);

  aRenderingContext.SetFont(GetStyleFont()->mFont,
                            presContext->GetUserFontSet());
  nsCOMPtr<nsIFontMetrics> fm;
  aRenderingContext.GetFontMetrics(*getter_AddRefs(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);

  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->GetEmHeight(em);
    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 = 0;
      fm->GetXHeight (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;
}
Exemple #7
0
void
nsTextBoxFrame::DrawText(nsIRenderingContext& aRenderingContext,
                         const nsRect&        aTextRect,
                         const nscolor*       aOverrideColor)
{
    nsPresContext* presContext = PresContext();

    // paint the title
    nscolor overColor;
    nscolor underColor;
    nscolor strikeColor;
    nsStyleContext* context = mStyleContext;
  
    PRUint8 decorations = NS_STYLE_TEXT_DECORATION_NONE; // Begin with no decorations
    PRUint8 decorMask = NS_STYLE_TEXT_DECORATION_UNDERLINE | NS_STYLE_TEXT_DECORATION_OVERLINE |
                        NS_STYLE_TEXT_DECORATION_LINE_THROUGH; // A mask of all possible decorations.
    PRBool hasDecorations = context->HasTextDecorations();

    do {  // find decoration colors
      const nsStyleTextReset* styleText = context->GetStyleTextReset();
      
      if (decorMask & styleText->mTextDecoration) {  // a decoration defined here
        nscolor color = aOverrideColor ? *aOverrideColor : context->GetStyleColor()->mColor;
    
        if (NS_STYLE_TEXT_DECORATION_UNDERLINE & decorMask & styleText->mTextDecoration) {
          underColor = color;
          decorMask &= ~NS_STYLE_TEXT_DECORATION_UNDERLINE;
          decorations |= NS_STYLE_TEXT_DECORATION_UNDERLINE;
        }
        if (NS_STYLE_TEXT_DECORATION_OVERLINE & decorMask & styleText->mTextDecoration) {
          overColor = color;
          decorMask &= ~NS_STYLE_TEXT_DECORATION_OVERLINE;
          decorations |= NS_STYLE_TEXT_DECORATION_OVERLINE;
        }
        if (NS_STYLE_TEXT_DECORATION_LINE_THROUGH & decorMask & styleText->mTextDecoration) {
          strikeColor = color;
          decorMask &= ~NS_STYLE_TEXT_DECORATION_LINE_THROUGH;
          decorations |= NS_STYLE_TEXT_DECORATION_LINE_THROUGH;
        }
      }
      if (0 != decorMask) {
        context = context->GetParent();
        if (context) {
          hasDecorations = context->HasTextDecorations();
        }
      }
    } while (context && hasDecorations && (0 != decorMask));

    nsCOMPtr<nsIFontMetrics> fontMet;
    nsLayoutUtils::GetFontMetricsForFrame(this, getter_AddRefs(fontMet));

    nscoord offset;
    nscoord size;
    nscoord ascent;
    fontMet->GetMaxAscent(ascent);

    nscoord baseline =
      presContext->RoundAppUnitsToNearestDevPixels(aTextRect.y + ascent);
    nsRefPtr<gfxContext> ctx = aRenderingContext.ThebesContext();
    gfxPoint pt(presContext->AppUnitsToGfxUnits(aTextRect.x),
                presContext->AppUnitsToGfxUnits(aTextRect.y));
    gfxFloat width = presContext->AppUnitsToGfxUnits(aTextRect.width);
    gfxFloat ascentPixel = presContext->AppUnitsToGfxUnits(ascent);

    // Underlines are drawn before overlines, and both before the text
    // itself, per http://www.w3.org/TR/CSS21/zindex.html point 7.2.1.4.1.1.
    // (We don't apply this rule to the access-key underline because we only
    // find out where that is as a side effect of drawing the text, in the
    // general case -- see below.)
    if (decorations & (NS_FONT_DECORATION_OVERLINE |
                       NS_FONT_DECORATION_UNDERLINE)) {
      fontMet->GetUnderline(offset, size);
      gfxFloat offsetPixel = presContext->AppUnitsToGfxUnits(offset);
      gfxFloat sizePixel = presContext->AppUnitsToGfxUnits(size);
      if (decorations & NS_FONT_DECORATION_UNDERLINE) {
        nsCSSRendering::PaintDecorationLine(ctx, underColor,
                          pt, gfxSize(width, sizePixel),
                          ascentPixel, offsetPixel,
                          NS_STYLE_TEXT_DECORATION_UNDERLINE,
                          nsCSSRendering::DECORATION_STYLE_SOLID);
      }
      if (decorations & NS_FONT_DECORATION_OVERLINE) {
        nsCSSRendering::PaintDecorationLine(ctx, overColor,
                          pt, gfxSize(width, sizePixel),
                          ascentPixel, ascentPixel,
                          NS_STYLE_TEXT_DECORATION_OVERLINE,
                          nsCSSRendering::DECORATION_STYLE_SOLID);
      }
    }

    aRenderingContext.SetFont(fontMet);

    CalculateUnderline(aRenderingContext);

    aRenderingContext.SetColor(aOverrideColor ? *aOverrideColor : GetStyleColor()->mColor);

#ifdef IBMBIDI
    nsresult rv = NS_ERROR_FAILURE;

    if (mState & NS_FRAME_IS_BIDI) {
      presContext->SetBidiEnabled();
      nsBidiPresUtils* bidiUtils = presContext->GetBidiUtils();

      if (bidiUtils) {
        const nsStyleVisibility* vis = GetStyleVisibility();
        nsBidiDirection direction = (NS_STYLE_DIRECTION_RTL == vis->mDirection) ? NSBIDI_RTL : NSBIDI_LTR;
        if (mAccessKeyInfo && mAccessKeyInfo->mAccesskeyIndex != kNotFound) {
           // We let the RenderText function calculate the mnemonic's
           // underline position for us.
           nsBidiPositionResolve posResolve;
           posResolve.logicalIndex = mAccessKeyInfo->mAccesskeyIndex;
           rv = bidiUtils->RenderText(mCroppedTitle.get(), mCroppedTitle.Length(), direction,
                                      presContext, aRenderingContext,
                                      aTextRect.x, baseline,
                                      &posResolve,
                                      1);
           mAccessKeyInfo->mBeforeWidth = posResolve.visualLeftTwips;
           mAccessKeyInfo->mAccessWidth = posResolve.visualWidth;
        }
        else
        {
           rv = bidiUtils->RenderText(mCroppedTitle.get(), mCroppedTitle.Length(), direction,
                                      presContext, aRenderingContext,
                                      aTextRect.x, baseline);
        }
      }
    }
    if (NS_FAILED(rv) )
#endif // IBMBIDI
    {
       aRenderingContext.SetTextRunRTL(PR_FALSE);

       if (mAccessKeyInfo && mAccessKeyInfo->mAccesskeyIndex != kNotFound) {
           // In the simple (non-BiDi) case, we calculate the mnemonic's
           // underline position by getting the text metric.
           // XXX are attribute values always two byte?
           if (mAccessKeyInfo->mAccesskeyIndex > 0)
               aRenderingContext.GetWidth(mCroppedTitle.get(), mAccessKeyInfo->mAccesskeyIndex,
                                          mAccessKeyInfo->mBeforeWidth);
           else
               mAccessKeyInfo->mBeforeWidth = 0;
       }

       aRenderingContext.DrawString(mCroppedTitle, aTextRect.x, baseline);
    }

    if (mAccessKeyInfo && mAccessKeyInfo->mAccesskeyIndex != kNotFound) {
        aRenderingContext.FillRect(aTextRect.x + mAccessKeyInfo->mBeforeWidth,
                                   aTextRect.y + mAccessKeyInfo->mAccessOffset,
                                   mAccessKeyInfo->mAccessWidth,
                                   mAccessKeyInfo->mAccessUnderlineSize);
    }

    // Strikeout is drawn on top of the text, per
    // http://www.w3.org/TR/CSS21/zindex.html point 7.2.1.4.1.1.
    if (decorations & NS_FONT_DECORATION_LINE_THROUGH) {
      fontMet->GetStrikeout(offset, size);
      gfxFloat offsetPixel = presContext->AppUnitsToGfxUnits(offset);
      gfxFloat sizePixel = presContext->AppUnitsToGfxUnits(size);
      nsCSSRendering::PaintDecorationLine(ctx, strikeColor,
                        pt, gfxSize(width, sizePixel), ascentPixel, offsetPixel,
                        NS_STYLE_TEXT_DECORATION_LINE_THROUGH,
                        nsCSSRendering::DECORATION_STYLE_SOLID);
    }
}
/* virtual */ nsresult
nsMathMLmencloseFrame::PlaceInternal(nsIRenderingContext& aRenderingContext,
                                     PRBool               aPlaceOrigin,
                                     nsHTMLReflowMetrics& aDesiredSize,
                                     PRBool               aWidthOnly)
{
  ///////////////
  // Measure the size of our content using the base class to format like an
  // inferred mrow.
  nsHTMLReflowMetrics baseSize;
  nsresult rv =
    nsMathMLContainerFrame::Place(aRenderingContext, PR_FALSE, baseSize);

  if (NS_MATHML_HAS_ERROR(mPresentationData.flags) || NS_FAILED(rv)) {
      DidReflowChildren(GetFirstChild(nsnull));
      return rv;
    }

  nsBoundingMetrics bmBase = baseSize.mBoundingMetrics;
  nscoord dx_left = 0, dx_right = 0;
  nsBoundingMetrics bmLongdivChar, bmRadicalChar;
  nscoord radicalAscent = 0, radicalDescent = 0;
  nscoord longdivAscent = 0, longdivDescent = 0;
  nscoord psi = 0;

  ///////////////
  // Thickness of bars and font metrics
  nscoord onePixel = nsPresContext::CSSPixelsToAppUnits(1);
  nsCOMPtr<nsIFontMetrics> fm;
  nscoord mEmHeight;
  aRenderingContext.SetFont(GetStyleFont()->mFont,
                            PresContext()->GetUserFontSet());
  aRenderingContext.GetFontMetrics(*getter_AddRefs(fm));
  GetRuleThickness(aRenderingContext, fm, mRuleThickness);
  GetEmHeight(fm, mEmHeight);

  nsBoundingMetrics bmOne;
  aRenderingContext.GetBoundingMetrics(NS_LITERAL_STRING("1").get(), 1, bmOne);

  ///////////////
  // General rules: the menclose element takes the size of the enclosed content.
  // We add a padding when needed.

  // determine padding & psi
  nscoord padding = 3 * mRuleThickness;
  nscoord delta = padding % onePixel;
  if (delta)
    padding += onePixel - delta; // round up

  if (IsToDraw(NOTATION_LONGDIV) || IsToDraw(NOTATION_RADICAL)) {
      nscoord phi;
      // Rule 11, App. G, TeXbook
      // psi = clearance between rule and content
      if (NS_MATHML_IS_DISPLAYSTYLE(mPresentationData.flags))
        fm->GetXHeight(phi);
      else
        phi = mRuleThickness;
      psi = mRuleThickness + phi / 4;

      delta = psi % onePixel;
      if (delta)
        psi += onePixel - delta; // round up
    }

  if (mRuleThickness < onePixel)
    mRuleThickness = onePixel;
 
  // Set horizontal parameters
  if (IsToDraw(NOTATION_ROUNDEDBOX) ||
      IsToDraw(NOTATION_TOP) ||
      IsToDraw(NOTATION_LEFT) ||
      IsToDraw(NOTATION_BOTTOM) ||
      IsToDraw(NOTATION_CIRCLE))
    dx_left = padding;

  if (IsToDraw(NOTATION_ROUNDEDBOX) ||
      IsToDraw(NOTATION_TOP) ||
      IsToDraw(NOTATION_RIGHT) ||
      IsToDraw(NOTATION_BOTTOM) ||
      IsToDraw(NOTATION_CIRCLE))
    dx_right = padding;

  // Set vertical parameters
  if (IsToDraw(NOTATION_RIGHT) ||
      IsToDraw(NOTATION_LEFT) ||
      IsToDraw(NOTATION_UPDIAGONALSTRIKE) ||
      IsToDraw(NOTATION_DOWNDIAGONALSTRIKE) ||
      IsToDraw(NOTATION_VERTICALSTRIKE) ||
      IsToDraw(NOTATION_CIRCLE) ||
      IsToDraw(NOTATION_ROUNDEDBOX) ||
      IsToDraw(NOTATION_RADICAL) ||
      IsToDraw(NOTATION_LONGDIV)) {
      // set a minimal value for the base height
      bmBase.ascent = NS_MAX(bmOne.ascent, bmBase.ascent);
      bmBase.descent = NS_MAX(0, bmBase.descent);
  }

  mBoundingMetrics.ascent = bmBase.ascent;
  mBoundingMetrics.descent = bmBase.descent;
    
  if (IsToDraw(NOTATION_ROUNDEDBOX) ||
      IsToDraw(NOTATION_TOP) ||
      IsToDraw(NOTATION_LEFT) ||
      IsToDraw(NOTATION_RIGHT) ||
      IsToDraw(NOTATION_CIRCLE))
    mBoundingMetrics.ascent += padding;
  
  if (IsToDraw(NOTATION_ROUNDEDBOX) ||
      IsToDraw(NOTATION_LEFT) ||
      IsToDraw(NOTATION_RIGHT) ||
      IsToDraw(NOTATION_BOTTOM) ||
      IsToDraw(NOTATION_CIRCLE))
    mBoundingMetrics.descent += padding;

  ///////////////
  // circle notation: we don't want the ellipse to overlap the enclosed
  // content. Hence, we need to increase the size of the bounding box by a
  // factor of at least sqrt(2).
  if (IsToDraw(NOTATION_CIRCLE)) {
    double ratio = (sqrt(2.0) - 1.0) / 2.0;
    nscoord padding2;

    // Update horizontal parameters
    padding2 = ratio * bmBase.width;

    dx_left = NS_MAX(dx_left, padding2);
    dx_right = NS_MAX(dx_right, padding2);

    // Update vertical parameters
    padding2 = ratio * (bmBase.ascent + bmBase.descent);

    mBoundingMetrics.ascent = NS_MAX(mBoundingMetrics.ascent,
                                     bmBase.ascent + padding2);
    mBoundingMetrics.descent = NS_MAX(mBoundingMetrics.descent,
                                      bmBase.descent + padding2);
  }

  ///////////////
  // longdiv notation:
  if (IsToDraw(NOTATION_LONGDIV)) {
    if (aWidthOnly) {
        nscoord longdiv_width = mMathMLChar[mLongDivCharIndex].
          GetMaxWidth(PresContext(), aRenderingContext);

        // Update horizontal parameters
        dx_left = NS_MAX(dx_left, longdiv_width);
    } else {
      // Stretch the parenthesis to the appropriate height if it is not
      // big enough.
      nsBoundingMetrics contSize = bmBase;
      contSize.ascent = mRuleThickness;
      contSize.descent = bmBase.ascent + bmBase.descent + psi;

      // height(longdiv) should be >= height(base) + psi + mRuleThickness
      mMathMLChar[mLongDivCharIndex].Stretch(PresContext(), aRenderingContext,
                                             NS_STRETCH_DIRECTION_VERTICAL,
                                             contSize, bmLongdivChar,
                                             NS_STRETCH_LARGER);
      mMathMLChar[mLongDivCharIndex].GetBoundingMetrics(bmLongdivChar);

      // Update horizontal parameters
      dx_left = NS_MAX(dx_left, bmLongdivChar.width);

      // Update vertical parameters
      longdivAscent = bmBase.ascent + psi + mRuleThickness;
      longdivDescent = NS_MAX(bmBase.descent,
                              (bmLongdivChar.ascent + bmLongdivChar.descent -
                               longdivAscent));

      mBoundingMetrics.ascent = NS_MAX(mBoundingMetrics.ascent,
                                       longdivAscent);
      mBoundingMetrics.descent = NS_MAX(mBoundingMetrics.descent,
                                        longdivDescent);
    }
  }

  ///////////////
  // radical notation:
  if (IsToDraw(NOTATION_RADICAL)) {
    if (aWidthOnly) {
      nscoord radical_width = mMathMLChar[mRadicalCharIndex].
        GetMaxWidth(PresContext(), aRenderingContext);
      
      // Update horizontal parameters
      dx_left = NS_MAX(dx_left, radical_width);
    } else {
      // Stretch the radical symbol to the appropriate height if it is not
      // big enough.
      nsBoundingMetrics contSize = bmBase;
      contSize.ascent = mRuleThickness;
      contSize.descent = bmBase.ascent + bmBase.descent + psi;

      // height(radical) should be >= height(base) + psi + mRuleThickness
      mMathMLChar[mRadicalCharIndex].Stretch(PresContext(), aRenderingContext,
                                             NS_STRETCH_DIRECTION_VERTICAL,
                                             contSize, bmRadicalChar,
                                             NS_STRETCH_LARGER);
      mMathMLChar[mRadicalCharIndex].GetBoundingMetrics(bmRadicalChar);

      // Update horizontal parameters
      dx_left = NS_MAX(dx_left, bmRadicalChar.width);

      // Update vertical parameters
      radicalAscent = bmBase.ascent + psi + mRuleThickness;
      radicalDescent = NS_MAX(bmBase.descent,
                              (bmRadicalChar.ascent + bmRadicalChar.descent -
                               radicalAscent));

      mBoundingMetrics.ascent = NS_MAX(mBoundingMetrics.ascent,
                                       radicalAscent);
      mBoundingMetrics.descent = NS_MAX(mBoundingMetrics.descent,
                                        radicalDescent);
    }
  }

  ///////////////
  //
  if (IsToDraw(NOTATION_CIRCLE) ||
      IsToDraw(NOTATION_ROUNDEDBOX) ||
      (IsToDraw(NOTATION_LEFT) && IsToDraw(NOTATION_RIGHT))) {
    // center the menclose around the content (horizontally)
    dx_left = dx_right = NS_MAX(dx_left, dx_right);
  }

  ///////////////
  // The maximum size is now computed: set the remaining parameters
  mBoundingMetrics.width = dx_left + bmBase.width + dx_right;

  mBoundingMetrics.leftBearing = NS_MIN(0, dx_left + bmBase.leftBearing);
  mBoundingMetrics.rightBearing =
    NS_MAX(mBoundingMetrics.width, dx_left + bmBase.rightBearing);
  
  aDesiredSize.width = mBoundingMetrics.width;

  aDesiredSize.ascent = NS_MAX(mBoundingMetrics.ascent, baseSize.ascent);
  aDesiredSize.height = aDesiredSize.ascent +
    NS_MAX(mBoundingMetrics.descent, baseSize.height - baseSize.ascent);

  if (IsToDraw(NOTATION_LONGDIV) || IsToDraw(NOTATION_RADICAL)) {
    // get the leading to be left at the top of the resulting frame
    // this seems more reliable than using fm->GetLeading() on suspicious
    // fonts
    nscoord leading = nscoord(0.2f * mEmHeight);
    nscoord desiredSizeAscent = aDesiredSize.ascent;
    nscoord desiredSizeDescent = aDesiredSize.height - aDesiredSize.ascent;
    
    if (IsToDraw(NOTATION_LONGDIV)) {
      desiredSizeAscent = NS_MAX(desiredSizeAscent,
                                 longdivAscent + leading);
      desiredSizeDescent = NS_MAX(desiredSizeDescent,
                                  longdivDescent + mRuleThickness);
    }
    
    if (IsToDraw(NOTATION_RADICAL)) {
      desiredSizeAscent = NS_MAX(desiredSizeAscent,
                                 radicalAscent + leading);
      desiredSizeDescent = NS_MAX(desiredSizeDescent,
                                  radicalDescent + mRuleThickness);
    }

    aDesiredSize.ascent = desiredSizeAscent;
    aDesiredSize.height = desiredSizeAscent + desiredSizeDescent;
  }
    
  if (IsToDraw(NOTATION_CIRCLE) ||
      IsToDraw(NOTATION_ROUNDEDBOX) ||
      (IsToDraw(NOTATION_TOP) && IsToDraw(NOTATION_BOTTOM))) {
    // center the menclose around the content (vertically)
    nscoord dy = NS_MAX(aDesiredSize.ascent - bmBase.ascent,
                        aDesiredSize.height - aDesiredSize.ascent -
                        bmBase.descent);

    aDesiredSize.ascent = bmBase.ascent + dy;
    aDesiredSize.height = aDesiredSize.ascent + bmBase.descent + dy;
  }

  // Update mBoundingMetrics ascent/descent
  if (IsToDraw(NOTATION_TOP) ||
      IsToDraw(NOTATION_RIGHT) ||
      IsToDraw(NOTATION_LEFT) ||
      IsToDraw(NOTATION_UPDIAGONALSTRIKE) ||
      IsToDraw(NOTATION_DOWNDIAGONALSTRIKE) ||
      IsToDraw(NOTATION_VERTICALSTRIKE) ||
      IsToDraw(NOTATION_CIRCLE) ||
      IsToDraw(NOTATION_ROUNDEDBOX))
    mBoundingMetrics.ascent = aDesiredSize.ascent;
  
  if (IsToDraw(NOTATION_BOTTOM) ||
      IsToDraw(NOTATION_RIGHT) ||
      IsToDraw(NOTATION_LEFT) ||
      IsToDraw(NOTATION_UPDIAGONALSTRIKE) ||
      IsToDraw(NOTATION_DOWNDIAGONALSTRIKE) ||
      IsToDraw(NOTATION_VERTICALSTRIKE) ||
      IsToDraw(NOTATION_CIRCLE) ||
      IsToDraw(NOTATION_ROUNDEDBOX))
    mBoundingMetrics.descent = aDesiredSize.height - aDesiredSize.ascent;

  aDesiredSize.mBoundingMetrics = mBoundingMetrics;
  
  mReference.x = 0;
  mReference.y = aDesiredSize.ascent;

  if (aPlaceOrigin) {
    //////////////////
    // Set position and size of MathMLChars
    if (IsToDraw(NOTATION_LONGDIV))
      mMathMLChar[mLongDivCharIndex].SetRect(nsRect(dx_left -
                                                    bmLongdivChar.width,
                                                    aDesiredSize.ascent -
                                                    longdivAscent,
                                                    bmLongdivChar.width,
                                                    bmLongdivChar.ascent +
                                                    bmLongdivChar.descent));

    if (IsToDraw(NOTATION_RADICAL))
      mMathMLChar[mRadicalCharIndex].SetRect(nsRect(dx_left -
                                                    bmRadicalChar.width,
                                                    aDesiredSize.ascent -
                                                    radicalAscent,
                                                    bmRadicalChar.width,
                                                    bmRadicalChar.ascent +
                                                    bmRadicalChar.descent));

    mContentWidth = bmBase.width;

    //////////////////
    // Finish reflowing child frames
    PositionRowChildFrames(dx_left, aDesiredSize.ascent);
  }

  return NS_OK;
}
Exemple #9
0
/* 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
    NS_WARNING("invalid markup");
    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);
  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 = PR_MAX(onePixel, coreData.leftSpace);
  nscoord rightSpace = PR_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 = PR_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 =
    PR_MAX(dxNum + bmNum.rightBearing, dxDen + bmDen.rightBearing);
  if (mBoundingMetrics.rightBearing < width - rightSpace)
    mBoundingMetrics.rightBearing = width - rightSpace;
  mBoundingMetrics.leftBearing =
    PR_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;
}
/* virtual */ nsresult
nsMathMLmunderFrame::Place(nsIRenderingContext& aRenderingContext,
                           PRBool               aPlaceOrigin,
                           nsHTMLReflowMetrics& aDesiredSize)
{
  if ( NS_MATHML_EMBELLISH_IS_MOVABLELIMITS(mEmbellishData.flags) &&
      !NS_MATHML_IS_DISPLAYSTYLE(mPresentationData.flags)) {
    // place like subscript
    return nsMathMLmsubFrame::PlaceSubScript(PresContext(),
                                             aRenderingContext,
                                             aPlaceOrigin,
                                             aDesiredSize,
                                             this, 0, nsPresContext::CSSPointsToAppUnits(0.5f));
  }

  ////////////////////////////////////
  // Get the children's desired sizes

  nsBoundingMetrics bmBase, bmUnder;
  nsHTMLReflowMetrics baseSize;
  nsHTMLReflowMetrics underSize;
  nsIFrame* underFrame = nsnull;
  nsIFrame* baseFrame = mFrames.FirstChild();
  if (baseFrame)
    underFrame = baseFrame->GetNextSibling();
  if (!baseFrame || !underFrame || underFrame->GetNextSibling()) {
    // report an error, encourage people to get their markups in order
    return ReflowError(aRenderingContext, aDesiredSize);
  }
  GetReflowAndBoundingMetricsFor(baseFrame, baseSize, bmBase);
  GetReflowAndBoundingMetricsFor(underFrame, underSize, bmUnder);

  nscoord onePixel = nsPresContext::CSSPixelsToAppUnits(1);

  ////////////////////
  // Place Children

  aRenderingContext.SetFont(GetStyleFont()->mFont,
                            PresContext()->GetUserFontSet());
  nsCOMPtr<nsIFontMetrics> fm;
  aRenderingContext.GetFontMetrics(*getter_AddRefs(fm));

  nscoord xHeight = 0;
  fm->GetXHeight (xHeight);

  nscoord ruleThickness;
  GetRuleThickness (aRenderingContext, fm, ruleThickness);

  // there are 2 different types of placement depending on 
  // whether we want an accented under or not

  nscoord correction = 0;
  GetItalicCorrection (bmBase, correction);

  nscoord delta1 = 0; // gap between base and underscript
  nscoord delta2 = 0; // extra space beneath underscript
  if (!NS_MATHML_EMBELLISH_IS_ACCENTUNDER(mEmbellishData.flags)) {    
    // Rule 13a, App. G, TeXbook
    nscoord bigOpSpacing2, bigOpSpacing4, bigOpSpacing5, dummy; 
    GetBigOpSpacings (fm, 
                      dummy, bigOpSpacing2, 
                      dummy, bigOpSpacing4, 
                      bigOpSpacing5);
    delta1 = NS_MAX(bigOpSpacing2, (bigOpSpacing4 - bmUnder.ascent));
    delta2 = bigOpSpacing5;
  }
  else {
    // No corresponding rule in TeXbook - we are on our own here
    // XXX tune the gap delta between base and underscript 

    // Should we use Rule 10 like \underline does?
    delta1 = ruleThickness + onePixel/2;
    delta2 = ruleThickness;
  }
  // empty under?
  if (!(bmUnder.ascent + bmUnder.descent)) delta1 = 0;

  nscoord dxBase, dxUnder = 0;

  // Width of non-spacing marks is zero so use left and right bearing.
  nscoord underWidth = bmUnder.width;
  if (!underWidth) {
    underWidth = bmUnder.rightBearing - bmUnder.leftBearing;
    dxUnder = -bmUnder.leftBearing;
  }

  nscoord maxWidth = NS_MAX(bmBase.width, underWidth);
  if (NS_MATHML_EMBELLISH_IS_ACCENTUNDER(mEmbellishData.flags)) {    
    dxUnder += (maxWidth - underWidth)/2;
  }
  else {
    dxUnder += -correction/2 + (maxWidth - underWidth)/2;
  }
  dxBase = (maxWidth - bmBase.width)/2;

  mBoundingMetrics.width =
    NS_MAX(dxBase + bmBase.width, dxUnder + bmUnder.width);
  mBoundingMetrics.ascent = bmBase.ascent;
  mBoundingMetrics.descent = 
    bmBase.descent + delta1 + bmUnder.ascent + bmUnder.descent;
  mBoundingMetrics.leftBearing = 
    NS_MIN(dxBase + bmBase.leftBearing, dxUnder + bmUnder.leftBearing);
  mBoundingMetrics.rightBearing = 
    NS_MAX(dxBase + bmBase.rightBearing, dxUnder + bmUnder.rightBearing);

  aDesiredSize.ascent = baseSize.ascent;
  aDesiredSize.height = aDesiredSize.ascent +
    NS_MAX(mBoundingMetrics.descent + delta2,
           bmBase.descent + delta1 + bmUnder.ascent +
             underSize.height - underSize.ascent);
  aDesiredSize.width = mBoundingMetrics.width;
  aDesiredSize.mBoundingMetrics = mBoundingMetrics;

  mReference.x = 0;
  mReference.y = aDesiredSize.ascent;

  if (aPlaceOrigin) {
    nscoord dy = 0;
    // place base
    FinishReflowChild(baseFrame, PresContext(), nsnull, baseSize, dxBase, dy, 0);
    // place underscript
    dy = aDesiredSize.ascent + mBoundingMetrics.descent - bmUnder.descent - underSize.ascent;
    FinishReflowChild(underFrame, PresContext(), nsnull, underSize, dxUnder, dy, 0);
  }

  return NS_OK;
}