C++ nsHTMLReflowMetrics::BlockStartAscent方法代码示例

void
nsMathMLmpaddedFrame::UpdateValue(int32_t                  aSign,
                                  int32_t                  aPseudoUnit,
                                  const nsCSSValue&        aCSSValue,
                                  const nsHTMLReflowMetrics& aDesiredSize,
                                  nscoord&                 aValueToUpdate,
                                  float                aFontSizeInflation) const
{
  nsCSSUnit unit = aCSSValue.GetUnit();
  if (NS_MATHML_SIGN_INVALID != aSign && eCSSUnit_Null != unit) {
    nscoord scaler = 0, amount = 0;

    if (eCSSUnit_Percent == unit || eCSSUnit_Number == unit) {
      switch(aPseudoUnit) {
        case NS_MATHML_PSEUDO_UNIT_WIDTH:
             scaler = aDesiredSize.Width();
             break;

        case NS_MATHML_PSEUDO_UNIT_HEIGHT:
             scaler = aDesiredSize.BlockStartAscent();
             break;

        case NS_MATHML_PSEUDO_UNIT_DEPTH:
             scaler = aDesiredSize.Height() - aDesiredSize.BlockStartAscent();
             break;

        default:
          // if we ever reach here, it would mean something is wrong 
          // somewhere with the setup and/or the caller
          NS_ERROR("Unexpected Pseudo Unit");
          return;
      }
    }

    if (eCSSUnit_Number == unit)
      amount = NSToCoordRound(float(scaler) * aCSSValue.GetFloatValue());
    else if (eCSSUnit_Percent == unit)
      amount = NSToCoordRound(float(scaler) * aCSSValue.GetPercentValue());
    else
      amount = CalcLength(PresContext(), mStyleContext, aCSSValue,
                          aFontSizeInflation);

    if (NS_MATHML_SIGN_PLUS == aSign)
      aValueToUpdate += amount;
    else if (NS_MATHML_SIGN_MINUS == aSign)
      aValueToUpdate -= amount;
    else
      aValueToUpdate  = amount;
  }
}

void
nsMathMLmspaceFrame::Reflow(nsPresContext*          aPresContext,
                            nsHTMLReflowMetrics&     aDesiredSize,
                            const nsHTMLReflowState& aReflowState,
                            nsReflowStatus&          aStatus)
{
  MarkInReflow();
  mPresentationData.flags &= ~NS_MATHML_ERROR;
  ProcessAttributes(aPresContext);

  mBoundingMetrics = nsBoundingMetrics();
  mBoundingMetrics.width = mWidth;
  mBoundingMetrics.ascent = mHeight;
  mBoundingMetrics.descent = mDepth;
  mBoundingMetrics.leftBearing = 0;
  mBoundingMetrics.rightBearing = mBoundingMetrics.width;

  aDesiredSize.SetBlockStartAscent(mHeight);
  aDesiredSize.Width() = std::max(0, mBoundingMetrics.width);
  aDesiredSize.Height() = aDesiredSize.BlockStartAscent() + mDepth;
  // Also return our bounding metrics
  aDesiredSize.mBoundingMetrics = mBoundingMetrics;

  aStatus = NS_FRAME_COMPLETE;
  NS_FRAME_SET_TRUNCATION(aStatus, aReflowState, aDesiredSize);
}

// For token elements, mBoundingMetrics is computed at the ReflowToken
// pass, it is not computed here because our children may be text frames
// that do not implement the GetBoundingMetrics() interface.
/* virtual */ nsresult
nsMathMLTokenFrame::Place(DrawTarget*          aDrawTarget,
                          bool                 aPlaceOrigin,
                          nsHTMLReflowMetrics& aDesiredSize)
{
  mBoundingMetrics = nsBoundingMetrics();
  for (nsIFrame* childFrame = GetFirstPrincipalChild(); childFrame;
       childFrame = childFrame->GetNextSibling()) {
    nsHTMLReflowMetrics childSize(aDesiredSize.GetWritingMode());
    GetReflowAndBoundingMetricsFor(childFrame, childSize,
                                   childSize.mBoundingMetrics, nullptr);
    // compute and cache the bounding metrics
    mBoundingMetrics += childSize.mBoundingMetrics;
  }

  RefPtr<nsFontMetrics> fm;
  nsLayoutUtils::GetFontMetricsForFrame(this, getter_AddRefs(fm),
                                        nsLayoutUtils::
                                        FontSizeInflationFor(this));
  nscoord ascent = fm->MaxAscent();
  nscoord descent = fm->MaxDescent();

  aDesiredSize.mBoundingMetrics = mBoundingMetrics;
  aDesiredSize.Width() = mBoundingMetrics.width;
  aDesiredSize.SetBlockStartAscent(std::max(mBoundingMetrics.ascent, ascent));
  aDesiredSize.Height() = aDesiredSize.BlockStartAscent() +
                        std::max(mBoundingMetrics.descent, descent);

  if (aPlaceOrigin) {
    nscoord dy, dx = 0;
    for (nsIFrame* childFrame = GetFirstPrincipalChild(); childFrame;
         childFrame = childFrame->GetNextSibling()) {
      nsHTMLReflowMetrics childSize(aDesiredSize.GetWritingMode());
      GetReflowAndBoundingMetricsFor(childFrame, childSize,
                                     childSize.mBoundingMetrics);

      // place and size the child; (dx,0) makes the caret happy - bug 188146
      dy = childSize.Height() == 0 ? 0 : aDesiredSize.BlockStartAscent() - childSize.BlockStartAscent();
      FinishReflowChild(childFrame, PresContext(), childSize, nullptr, dx, dy, 0);
      dx += childSize.Width();
    }
  }

  SetReference(nsPoint(0, aDesiredSize.BlockStartAscent()));

  return NS_OK;
}

nsresult
nsMathMLmoFrame::Place(nsRenderingContext&  aRenderingContext,
                       bool                 aPlaceOrigin,
                       nsHTMLReflowMetrics& aDesiredSize)
{
  nsresult rv = nsMathMLTokenFrame::Place(aRenderingContext, aPlaceOrigin,
                                          aDesiredSize);

  if (NS_FAILED(rv)) {
    return rv;
  }

  /* Special behaviour for largeops.
     In MathML "stretchy" and displaystyle "largeop" are different notions,
     even if we use the same technique to draw them (picking size variants).
     So largeop display operators should be considered "non-stretchy" and
     thus their sizes should be taken into account for the stretch size of
     other elements.

     This is a preliminary stretch - exact sizing/placement is handled by the
     Stretch() method.
  */

  if (!aPlaceOrigin &&
      StyleFont()->mMathDisplay == NS_MATHML_DISPLAYSTYLE_BLOCK &&
      NS_MATHML_OPERATOR_IS_LARGEOP(mFlags) && UseMathMLChar()) {
    nsBoundingMetrics newMetrics;
    rv = mMathMLChar.Stretch(PresContext(), aRenderingContext,
                                      nsLayoutUtils::FontSizeInflationFor(this),
                                      NS_STRETCH_DIRECTION_VERTICAL,
                                      aDesiredSize.mBoundingMetrics, newMetrics,
                                      NS_STRETCH_LARGEOP, StyleVisibility()->mDirection);

    if (NS_FAILED(rv)) {
      // Just use the initial size
      return NS_OK;
    }

    aDesiredSize.mBoundingMetrics = newMetrics;
     /* Treat the ascent/descent values calculated in the TokenFrame place
       calculations as the minimum for aDesiredSize calculations, rather
       than fetching them from font metrics again.
    */
    aDesiredSize.SetBlockStartAscent(std::max(mBoundingMetrics.ascent,
                                              newMetrics.ascent));
    aDesiredSize.Height() = aDesiredSize.BlockStartAscent() +
                            std::max(mBoundingMetrics.descent,
                                     newMetrics.descent);
    aDesiredSize.Width() = newMetrics.width;
    mBoundingMetrics = newMetrics;
  }
  return NS_OK;
}

/* virtual */ void
nsRubyTextContainerFrame::Reflow(nsPresContext* aPresContext,
                                 nsHTMLReflowMetrics& aDesiredSize,
                                 const nsHTMLReflowState& aReflowState,
                                 nsReflowStatus& aStatus)
{
  DO_GLOBAL_REFLOW_COUNT("nsRubyTextContainerFrame");
  DISPLAY_REFLOW(aPresContext, this, aReflowState, aDesiredSize, aStatus);

  // All rt children have already been reflowed. All we need to do is clean up
  // the line layout.

  aStatus = NS_FRAME_COMPLETE;
  mozilla::WritingMode lineWM = aReflowState.mLineLayout->GetWritingMode();
  mozilla::WritingMode frameWM = aReflowState.GetWritingMode();
  mozilla::LogicalMargin borderPadding =
    aReflowState.ComputedLogicalBorderPadding();

  aDesiredSize.ISize(lineWM) = mISize;
  nsLayoutUtils::SetBSizeFromFontMetrics(this, aDesiredSize, aReflowState,
                                         borderPadding, lineWM, frameWM);

  nscoord bsize = aDesiredSize.BSize(lineWM);
  if (!mLines.empty()) {
    // Okay to use BlockStartAscent because it has just been correctly set by
    // nsLayoutUtils::SetBSizeFromFontMetrics.
    mLines.begin()->SetLogicalAscent(aDesiredSize.BlockStartAscent());
    mLines.begin()->SetBounds(aReflowState.GetWritingMode(), 0, 0, mISize,
                              bsize, mISize);
  }

  if (mLineLayout) {
    mLineLayout->EndLineReflow();
    mLineLayout = nullptr;
  }
}

/* virtual */ nsresult
nsMathMLmunderoverFrame::Place(nsRenderingContext& aRenderingContext,
                               bool                 aPlaceOrigin,
                               nsHTMLReflowMetrics& aDesiredSize)
{
  nsIAtom* tag = mContent->Tag();
  if (NS_MATHML_EMBELLISH_IS_MOVABLELIMITS(mEmbellishData.flags) &&
      StyleFont()->mMathDisplay == NS_MATHML_DISPLAYSTYLE_INLINE) {
    //place like sub sup or subsup
    if (tag == nsGkAtoms::munderover_) {
      return nsMathMLmmultiscriptsFrame::PlaceMultiScript(PresContext(),
                                                          aRenderingContext,
                                                          aPlaceOrigin,
                                                          aDesiredSize,
                                                          this, 0, 0);
    } else if (tag == nsGkAtoms::munder_) {
      return nsMathMLmmultiscriptsFrame::PlaceMultiScript(PresContext(),
                                                          aRenderingContext,
                                                          aPlaceOrigin,
                                                          aDesiredSize,
                                                          this, 0, 0);
    } else {
      NS_ASSERTION(tag == nsGkAtoms::mover_, "mContent->Tag() not recognized");
      return nsMathMLmmultiscriptsFrame::PlaceMultiScript(PresContext(),
                                                          aRenderingContext,
                                                          aPlaceOrigin,
                                                          aDesiredSize,
                                                          this, 0, 0);
    }
    
  }

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

  nsBoundingMetrics bmBase, bmUnder, bmOver;
  nsHTMLReflowMetrics baseSize(aDesiredSize.GetWritingMode());
  nsHTMLReflowMetrics underSize(aDesiredSize.GetWritingMode());
  nsHTMLReflowMetrics overSize(aDesiredSize.GetWritingMode());
  nsIFrame* overFrame = nullptr;
  nsIFrame* underFrame = nullptr;
  nsIFrame* baseFrame = mFrames.FirstChild();
  underSize.SetBlockStartAscent(0);
  overSize.SetBlockStartAscent(0);
  bool haveError = false;
  if (baseFrame) {
    if (tag == nsGkAtoms::munder_ ||
        tag == nsGkAtoms::munderover_) {
      underFrame = baseFrame->GetNextSibling();
    } else if (tag == nsGkAtoms::mover_) {
      overFrame = baseFrame->GetNextSibling();
    }
  }
  if (underFrame && tag == nsGkAtoms::munderover_) {
    overFrame = underFrame->GetNextSibling();
  }
  
  if (tag == nsGkAtoms::munder_) {
    if (!baseFrame || !underFrame || underFrame->GetNextSibling()) {
      // report an error, encourage people to get their markups in order
      haveError = true;
    }
  }
  if (tag == nsGkAtoms::mover_) {
    if (!baseFrame || !overFrame || overFrame->GetNextSibling()) {
      // report an error, encourage people to get their markups in order
      haveError = true;
    }
  }
  if (tag == nsGkAtoms::munderover_) {
    if (!baseFrame || !underFrame || !overFrame || overFrame->GetNextSibling()) {
      // report an error, encourage people to get their markups in order
      haveError = true;
    }
  }
  if (haveError) {
    if (aPlaceOrigin) {
      ReportChildCountError();
    } 
    return ReflowError(aRenderingContext, aDesiredSize);
  }
  GetReflowAndBoundingMetricsFor(baseFrame, baseSize, bmBase);
  if (underFrame) {
    GetReflowAndBoundingMetricsFor(underFrame, underSize, bmUnder);
  }
  if (overFrame) {
    GetReflowAndBoundingMetricsFor(overFrame, overSize, bmOver);
  }

  nscoord onePixel = nsPresContext::CSSPixelsToAppUnits(1);

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

  nsRefPtr<nsFontMetrics> fm;
  nsLayoutUtils::GetFontMetricsForFrame(this, getter_AddRefs(fm));

  nscoord xHeight = fm->XHeight();
  nscoord oneDevPixel = fm->AppUnitsPerDevPixel();
  gfxFont* mathFont = fm->GetThebesFontGroup()->GetFirstMathFont();
//.........这里部分代码省略.........

void
nsMathMLmrootFrame::Reflow(nsPresContext*          aPresContext,
                           nsHTMLReflowMetrics&     aDesiredSize,
                           const nsHTMLReflowState& aReflowState,
                           nsReflowStatus&          aStatus)
{
  MarkInReflow();
  nsReflowStatus childStatus;

  mPresentationData.flags &= ~NS_MATHML_ERROR;
  aDesiredSize.ClearSize();
  aDesiredSize.SetBlockStartAscent(0);

  nsBoundingMetrics bmSqr, bmBase, bmIndex;
  DrawTarget* drawTarget = aReflowState.rendContext->GetDrawTarget();

  //////////////////
  // Reflow Children

  int32_t count = 0;
  nsIFrame* baseFrame = nullptr;
  nsIFrame* indexFrame = nullptr;
  nsHTMLReflowMetrics baseSize(aReflowState);
  nsHTMLReflowMetrics indexSize(aReflowState);
  nsIFrame* childFrame = mFrames.FirstChild();
  while (childFrame) {
    // ask our children to compute their bounding metrics 
    nsHTMLReflowMetrics childDesiredSize(aReflowState,
                                         aDesiredSize.mFlags
                                         | NS_REFLOW_CALC_BOUNDING_METRICS);
    WritingMode wm = childFrame->GetWritingMode();
    LogicalSize availSize = aReflowState.ComputedSize(wm);
    availSize.BSize(wm) = NS_UNCONSTRAINEDSIZE;
    nsHTMLReflowState childReflowState(aPresContext, aReflowState,
                                       childFrame, availSize);
    ReflowChild(childFrame, aPresContext,
                     childDesiredSize, childReflowState, childStatus);
    //NS_ASSERTION(NS_FRAME_IS_COMPLETE(childStatus), "bad status");
    if (0 == count) {
      // base 
      baseFrame = childFrame;
      baseSize = childDesiredSize;
      bmBase = childDesiredSize.mBoundingMetrics;
    }
    else if (1 == count) {
      // index
      indexFrame = childFrame;
      indexSize = childDesiredSize;
      bmIndex = childDesiredSize.mBoundingMetrics;
    }
    count++;
    childFrame = childFrame->GetNextSibling();
  }
  if (2 != count) {
    // report an error, encourage people to get their markups in order
    ReportChildCountError();
    ReflowError(drawTarget, aDesiredSize);
    aStatus = NS_FRAME_COMPLETE;
    NS_FRAME_SET_TRUNCATION(aStatus, aReflowState, aDesiredSize);
    // Call DidReflow() for the child frames we successfully did reflow.
    DidReflowChildren(mFrames.FirstChild(), childFrame);
    return;
  }

  ////////////
  // Prepare the radical symbol and the overline bar

  float fontSizeInflation = nsLayoutUtils::FontSizeInflationFor(this);
  RefPtr<nsFontMetrics> fm =
    nsLayoutUtils::GetFontMetricsForFrame(this, fontSizeInflation);

  nscoord ruleThickness, leading, psi;
  GetRadicalParameters(fm, StyleFont()->mMathDisplay ==
                       NS_MATHML_DISPLAYSTYLE_BLOCK,
                       ruleThickness, leading, psi);

  // built-in: adjust clearance psi to emulate \mathstrut using '1' (TexBook, p.131)
  char16_t one = '1';
  nsBoundingMetrics bmOne =
    nsLayoutUtils::AppUnitBoundsOfString(&one, 1, *fm, drawTarget);
  if (bmOne.ascent > bmBase.ascent)
    psi += bmOne.ascent - bmBase.ascent;

  // make sure that the rule appears on on screen
  nscoord onePixel = nsPresContext::CSSPixelsToAppUnits(1);
  if (ruleThickness < onePixel) {
    ruleThickness = onePixel;
  }

  // adjust clearance psi to get an exact number of pixels -- this
  // gives a nicer & uniform look on stacked radicals (bug 130282)
  nscoord delta = psi % onePixel;
  if (delta)
    psi += onePixel - delta; // round up

  // Stretch the radical symbol to the appropriate height if it is not big enough.
  nsBoundingMetrics contSize = bmBase;
  contSize.descent = bmBase.ascent + bmBase.descent + psi;
  contSize.ascent = ruleThickness;

//.........这里部分代码省略.........

void
BRFrame::Reflow(nsPresContext* aPresContext,
                nsHTMLReflowMetrics& aMetrics,
                const nsHTMLReflowState& aReflowState,
                nsReflowStatus& aStatus)
{
  MarkInReflow();
  DO_GLOBAL_REFLOW_COUNT("BRFrame");
  DISPLAY_REFLOW(aPresContext, this, aReflowState, aMetrics, aStatus);
  WritingMode wm = aReflowState.GetWritingMode();
  LogicalSize finalSize(wm);
  finalSize.BSize(wm) = 0; // BR frames with block size 0 are ignored in quirks
                           // mode by nsLineLayout::VerticalAlignFrames .
                           // However, it's not always 0.  See below.
  finalSize.ISize(wm) = 0;
  aMetrics.SetBlockStartAscent(0);

  // Only when the BR is operating in a line-layout situation will it
  // behave like a BR. Additionally, we suppress breaks from BR inside
  // of ruby frames. To determine if we're inside ruby, we have to rely
  // on the *parent's* ShouldSuppressLineBreak() method, instead of our
  // own, because we may have custom "display" value that makes our
  // ShouldSuppressLineBreak() return false.
  nsLineLayout* ll = aReflowState.mLineLayout;
  if (ll && !GetParent()->StyleContext()->ShouldSuppressLineBreak()) {
    // Note that the compatibility mode check excludes AlmostStandards
    // mode, since this is the inline box model.  See bug 161691.
    if ( ll->LineIsEmpty() ||
         aPresContext->CompatibilityMode() == eCompatibility_FullStandards ) {
      // The line is logically empty; any whitespace is trimmed away.
      //
      // If this frame is going to terminate the line we know
      // that nothing else will go on the line. Therefore, in this
      // case, we provide some height for the BR frame so that it
      // creates some vertical whitespace.  It's necessary to use the
      // line-height rather than the font size because the
      // quirks-mode fix that doesn't apply the block's min
      // line-height makes this necessary to make BR cause a line
      // of the full line-height

      // We also do this in strict mode because BR should act like a
      // normal inline frame.  That line-height is used is important
      // here for cases where the line-height is less than 1.
      RefPtr<nsFontMetrics> fm =
        nsLayoutUtils::GetInflatedFontMetricsForFrame(this);
      if (fm) {
        nscoord logicalHeight = aReflowState.CalcLineHeight();
        finalSize.BSize(wm) = logicalHeight;
        aMetrics.SetBlockStartAscent(nsLayoutUtils::GetCenteredFontBaseline(
                                       fm, logicalHeight, wm.IsLineInverted()));
      }
      else {
        aMetrics.SetBlockStartAscent(aMetrics.BSize(wm) = 0);
      }

      // XXX temporary until I figure out a better solution; see the
      // code in nsLineLayout::VerticalAlignFrames that zaps minY/maxY
      // if the width is zero.
      // XXX This also fixes bug 10036!
      // Warning: nsTextControlFrame::CalculateSizeStandard depends on
      // the following line, see bug 228752.
      // The code below in AddInlinePrefISize also adds 1 appunit to width
      finalSize.ISize(wm) = 1;
    }

    // Return our reflow status
    uint32_t breakType = aReflowState.mStyleDisplay->PhysicalBreakType(wm);
    if (NS_STYLE_CLEAR_NONE == breakType) {
      breakType = NS_STYLE_CLEAR_LINE;
    }

    aStatus = NS_INLINE_BREAK | NS_INLINE_BREAK_AFTER |
      NS_INLINE_MAKE_BREAK_TYPE(breakType);
    ll->SetLineEndsInBR(true);
  }
  else {
    aStatus = NS_FRAME_COMPLETE;
  }

  aMetrics.SetSize(wm, finalSize);
  aMetrics.SetOverflowAreasToDesiredBounds();

  mAscent = aMetrics.BlockStartAscent();

  NS_FRAME_SET_TRUNCATION(aStatus, aReflowState, aMetrics);
}

//.........这里部分代码省略.........
            (container.ascent + container.descent)/2 - container.ascent;
        } // else align the baselines
        mBoundingMetrics.ascent = height - mBoundingMetrics.descent;
      }
    }
  }

  // Fixup for the final height.
  // On one hand, our stretchy height can sometimes be shorter than surrounding
  // ASCII chars, e.g., arrow symbols have |mBoundingMetrics.ascent + leading|
  // that is smaller than the ASCII's ascent, hence when painting the background
  // later, it won't look uniform along the line.
  // On the other hand, sometimes we may leave too much gap when our glyph happens
  // to come from a font with tall glyphs. For example, since CMEX10 has very tall
  // glyphs, its natural font metrics are large, even if we pick a small glyph
  // whose size is comparable to the size of a normal ASCII glyph.
  // So to avoid uneven spacing in either of these two cases, we use the height
  // of the ASCII font as a reference and try to match it if possible.

  // special case for accents... keep them short to improve mouse operations...
  // an accent can only be the non-first child of <mover>, <munder>, <munderover>
  bool isAccent =
    NS_MATHML_EMBELLISH_IS_ACCENT(mEmbellishData.flags);
  if (isAccent) {
    nsEmbellishData parentData;
    GetEmbellishDataFrom(GetParent(), parentData);
    isAccent =
       (NS_MATHML_EMBELLISH_IS_ACCENTOVER(parentData.flags) ||
        NS_MATHML_EMBELLISH_IS_ACCENTUNDER(parentData.flags)) &&
       parentData.coreFrame != this;
  }
  if (isAccent && firstChild) {
    // see bug 188467 for what is going on here
    nscoord dy = aDesiredStretchSize.BlockStartAscent() -
      (mBoundingMetrics.ascent + leading);
    aDesiredStretchSize.SetBlockStartAscent(mBoundingMetrics.ascent + leading);
    aDesiredStretchSize.Height() = aDesiredStretchSize.BlockStartAscent() +
                                   mBoundingMetrics.descent;

    firstChild->SetPosition(firstChild->GetPosition() - nsPoint(0, dy));
  }
  else if (useMathMLChar) {
    nscoord ascent = fm->MaxAscent();
    nscoord descent = fm->MaxDescent();
    aDesiredStretchSize.SetBlockStartAscent(std::max(mBoundingMetrics.ascent + leading, ascent));
    aDesiredStretchSize.Height() = aDesiredStretchSize.BlockStartAscent() +
                                 std::max(mBoundingMetrics.descent + leading, descent);
  }
  aDesiredStretchSize.Width() = mBoundingMetrics.width;
  aDesiredStretchSize.mBoundingMetrics = mBoundingMetrics;
  mReference.x = 0;
  mReference.y = aDesiredStretchSize.BlockStartAscent();
  // Place our mMathMLChar, its origin is in our coordinate system
  if (useMathMLChar) {
    nscoord dy = aDesiredStretchSize.BlockStartAscent() - mBoundingMetrics.ascent;
    mMathMLChar.SetRect(nsRect(0, dy, charSize.width, charSize.ascent + charSize.descent));
  }

  // Before we leave... there is a last item in the check-list:
  // If our parent is not embellished, it means we are the outermost embellished
  // container and so we put the spacing, otherwise we don't include the spacing,
  // the outermost embellished container will take care of it.

  if (!NS_MATHML_OPERATOR_HAS_EMBELLISH_ANCESTOR(mFlags)) {

    // Account the spacing if we are not an accent with explicit attributes

/* virtual */ nsresult
nsMathMLmpaddedFrame::Place(nsRenderingContext& aRenderingContext,
                            bool                 aPlaceOrigin,
                            nsHTMLReflowMetrics& aDesiredSize)
{
  nsresult rv =
    nsMathMLContainerFrame::Place(aRenderingContext, false, aDesiredSize);
  if (NS_MATHML_HAS_ERROR(mPresentationData.flags) || NS_FAILED(rv)) {
    DidReflowChildren(GetFirstPrincipalChild());
    return rv;
  }

  nscoord height = aDesiredSize.BlockStartAscent();
  nscoord depth  = aDesiredSize.Height() - aDesiredSize.BlockStartAscent();
  // The REC says:
  //
  // "The lspace attribute ('leading' space) specifies the horizontal location
  // of the positioning point of the child content with respect to the
  // positioning point of the mpadded element. By default they coincide, and
  // therefore absolute values for lspace have the same effect as relative
  // values."
  //
  // "MathML renderers should ensure that, except for the effects of the
  // attributes, the relative spacing between the contents of the mpadded
  // element and surrounding MathML elements would not be modified by replacing
  // an mpadded element with an mrow element with the same content, even if
  // linebreaking occurs within the mpadded element."
  //
  // (http://www.w3.org/TR/MathML/chapter3.html#presm.mpadded)
  // 
  // "In those discussions, the terms leading and trailing are used to specify
  // a side of an object when which side to use depends on the directionality;
  // ie. leading means left in LTR but right in RTL."
  // (http://www.w3.org/TR/MathML/chapter3.html#presm.bidi.math)
  nscoord lspace = 0;
  // In MathML3, "width" will be the bounding box width and "advancewidth" will
  // refer "to the horizontal distance between the positioning point of the
  // mpadded and the positioning point for the following content".  MathML2
  // doesn't make the distinction.
  nscoord width  = aDesiredSize.Width();
  nscoord voffset = 0;

  int32_t pseudoUnit;
  nscoord initialWidth = width;
  float fontSizeInflation = nsLayoutUtils::FontSizeInflationFor(this);

  // update width
  pseudoUnit = (mWidthPseudoUnit == NS_MATHML_PSEUDO_UNIT_ITSELF)
             ? NS_MATHML_PSEUDO_UNIT_WIDTH : mWidthPseudoUnit;
  UpdateValue(mWidthSign, pseudoUnit, mWidth,
              aDesiredSize, width, fontSizeInflation);
  width = std::max(0, width);

  // update "height" (this is the ascent in the terminology of the REC)
  pseudoUnit = (mHeightPseudoUnit == NS_MATHML_PSEUDO_UNIT_ITSELF)
             ? NS_MATHML_PSEUDO_UNIT_HEIGHT : mHeightPseudoUnit;
  UpdateValue(mHeightSign, pseudoUnit, mHeight,
              aDesiredSize, height, fontSizeInflation);
  height = std::max(0, height);

  // update "depth" (this is the descent in the terminology of the REC)
  pseudoUnit = (mDepthPseudoUnit == NS_MATHML_PSEUDO_UNIT_ITSELF)
             ? NS_MATHML_PSEUDO_UNIT_DEPTH : mDepthPseudoUnit;
  UpdateValue(mDepthSign, pseudoUnit, mDepth,
              aDesiredSize, depth, fontSizeInflation);
  depth = std::max(0, depth);

  // update lspace
  if (mLeadingSpacePseudoUnit != NS_MATHML_PSEUDO_UNIT_ITSELF) {
    pseudoUnit = mLeadingSpacePseudoUnit;
    UpdateValue(mLeadingSpaceSign, pseudoUnit, mLeadingSpace,
                aDesiredSize, lspace, fontSizeInflation);
  }

  // update voffset
  if (mVerticalOffsetPseudoUnit != NS_MATHML_PSEUDO_UNIT_ITSELF) {
    pseudoUnit = mVerticalOffsetPseudoUnit;
    UpdateValue(mVerticalOffsetSign, pseudoUnit, mVerticalOffset,
                aDesiredSize, voffset, fontSizeInflation);
  }
  // do the padding now that we have everything
  // The idea here is to maintain the invariant that <mpadded>...</mpadded> (i.e.,
  // with no attributes) looks the same as <mrow>...</mrow>. But when there are
  // attributes, tweak our metrics and move children to achieve the desired visual
  // effects.

  if ((StyleVisibility()->mDirection ?
       mWidthSign : mLeadingSpaceSign) != NS_MATHML_SIGN_INVALID) {
    // there was padding on the left. dismiss the left italic correction now
    // (so that our parent won't correct us)
    mBoundingMetrics.leftBearing = 0;
  }

  if ((StyleVisibility()->mDirection ?
       mLeadingSpaceSign : mWidthSign) != NS_MATHML_SIGN_INVALID) {
    // there was padding on the right. dismiss the right italic correction now
    // (so that our parent won't correct us)
    mBoundingMetrics.width = width;
    mBoundingMetrics.rightBearing = mBoundingMetrics.width;
  }
//.........这里部分代码省略.........

//.........这里部分代码省略.........
    } else {
      // everything else = T,S,SS
      supScriptShift = supScriptShift2;
    }
  }

  if (0 < aUserSupScriptShift) {
    // the user has set the supscriptshift attribute
    supScriptShift = std::max(supScriptShift, aUserSupScriptShift);
  }

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

  const WritingMode wm(aDesiredSize.GetWritingMode());
  nscoord width = 0, prescriptsWidth = 0, rightBearing = 0;
  nscoord minSubScriptShift = 0, minSupScriptShift = 0;
  nscoord trySubScriptShift = subScriptShift;
  nscoord trySupScriptShift = supScriptShift;
  nscoord maxSubScriptShift = subScriptShift;
  nscoord maxSupScriptShift = supScriptShift;
  nsHTMLReflowMetrics baseSize(wm);
  nsHTMLReflowMetrics subScriptSize(wm);
  nsHTMLReflowMetrics supScriptSize(wm);
  nsHTMLReflowMetrics multiSubSize(wm), multiSupSize(wm);
  baseFrame = nullptr;
  nsIFrame* subScriptFrame = nullptr;
  nsIFrame* supScriptFrame = nullptr;
  nsIFrame* prescriptsFrame = nullptr; // frame of <mprescripts/>, if there.

  bool firstPrescriptsPair = false;
  nsBoundingMetrics bmBase, bmSubScript, bmSupScript, bmMultiSub, bmMultiSup;
  multiSubSize.SetBlockStartAscent(-0x7FFFFFFF);
  multiSupSize.SetBlockStartAscent(-0x7FFFFFFF);
  bmMultiSub.ascent = bmMultiSup.ascent = -0x7FFFFFFF;
  bmMultiSub.descent = bmMultiSup.descent = -0x7FFFFFFF;
  nscoord italicCorrection = 0;

  nsBoundingMetrics boundingMetrics;
  boundingMetrics.width = 0;
  boundingMetrics.ascent = boundingMetrics.descent = -0x7FFFFFFF;
  aDesiredSize.Width() = aDesiredSize.Height() = 0;

  int32_t count = 0;
  bool foundNoneTag = false;

  // Boolean to determine whether the current child is a subscript.
  // Note that only msup starts with a superscript.
  bool isSubScript = (tag != nsGkAtoms::msup_);

  nsIFrame* childFrame = aFrame->GetFirstPrincipalChild();
  while (childFrame) {
    if (childFrame->GetContent()->IsMathMLElement(nsGkAtoms::mprescripts_)) {
      if (tag != nsGkAtoms::mmultiscripts_) {
        if (aPlaceOrigin) {
          aFrame->ReportInvalidChildError(nsGkAtoms::mprescripts_);
        }
        return aFrame->ReflowError(aRenderingContext, aDesiredSize);
      }
      if (prescriptsFrame) {
        // duplicate <mprescripts/> found
        // report an error, encourage people to get their markups in order
        if (aPlaceOrigin) {
          aFrame->ReportErrorToConsole("DuplicateMprescripts");
        }

void
nsMathMLmfencedFrame::Reflow(nsPresContext*          aPresContext,
                             nsHTMLReflowMetrics&     aDesiredSize,
                             const nsHTMLReflowState& aReflowState,
                             nsReflowStatus&          aStatus)
{
  MarkInReflow();
  mPresentationData.flags &= ~NS_MATHML_ERROR;
  aDesiredSize.ClearSize();
  aDesiredSize.SetBlockStartAscent(0);
  aDesiredSize.mBoundingMetrics = nsBoundingMetrics();

  int32_t i;
  const nsStyleFont* font = StyleFont();
  float fontSizeInflation = nsLayoutUtils::FontSizeInflationFor(this);
  RefPtr<nsFontMetrics> fm;
  nsLayoutUtils::GetFontMetricsForFrame(this, getter_AddRefs(fm),
                                        fontSizeInflation);
  nscoord axisHeight, em;
  GetAxisHeight(*aReflowState.rendContext, fm, axisHeight);
  GetEmHeight(fm, em);
  // leading to be left at the top and the bottom of stretched chars
  nscoord leading = NSToCoordRound(0.2f * em); 

  /////////////
  // Reflow children
  // Asking each child to cache its bounding metrics

  // Note that we don't use the base method nsMathMLContainerFrame::Reflow()
  // because we want to stretch our fences, separators and stretchy frames using
  // the *same* initial aDesiredSize.mBoundingMetrics. If we were to use the base
  // method here, our stretchy frames will be stretched and placed, and we may
  // end up stretching our fences/separators with a different aDesiredSize.
  // XXX The above decision was revisited in bug 121748 and this code can be
  // refactored to use nsMathMLContainerFrame::Reflow() at some stage.

  nsReflowStatus childStatus;
  nsIFrame* firstChild = GetFirstPrincipalChild();
  nsIFrame* childFrame = firstChild;
  nscoord ascent = 0, descent = 0;
  if (firstChild || mOpenChar || mCloseChar || mSeparatorsCount > 0) {
    // We use the ASCII metrics to get our minimum height. This way,
    // if we have borders or a background, they will fit better with
    // other elements on the line.
    ascent = fm->MaxAscent();
    descent = fm->MaxDescent();
  }
  while (childFrame) {
    nsHTMLReflowMetrics childDesiredSize(aReflowState,
                                         aDesiredSize.mFlags
                                         | NS_REFLOW_CALC_BOUNDING_METRICS);
    WritingMode wm = childFrame->GetWritingMode();
    LogicalSize availSize = aReflowState.ComputedSize(wm);
    availSize.BSize(wm) = NS_UNCONSTRAINEDSIZE;
    nsHTMLReflowState childReflowState(aPresContext, aReflowState,
                                       childFrame, availSize);
    ReflowChild(childFrame, aPresContext, childDesiredSize,
                childReflowState, childStatus);
    //NS_ASSERTION(NS_FRAME_IS_COMPLETE(childStatus), "bad status");
    SaveReflowAndBoundingMetricsFor(childFrame, childDesiredSize,
                                    childDesiredSize.mBoundingMetrics);

    mozilla::WritingMode outerWM = aReflowState.GetWritingMode();
    nscoord childDescent = childDesiredSize.BSize(outerWM) -
                           childDesiredSize.BlockStartAscent();
    if (descent < childDescent)
      descent = childDescent;
    if (ascent < childDesiredSize.BlockStartAscent())
      ascent = childDesiredSize.BlockStartAscent();

    childFrame = childFrame->GetNextSibling();
  }

  /////////////
  // Ask stretchy children to stretch themselves

  nsBoundingMetrics containerSize;
  nsStretchDirection stretchDir = NS_STRETCH_DIRECTION_VERTICAL;

  GetPreferredStretchSize(*aReflowState.rendContext,
                          0, /* i.e., without embellishments */
                          stretchDir, containerSize);
  childFrame = firstChild;
  while (childFrame) {
    nsIMathMLFrame* mathmlChild = do_QueryFrame(childFrame);
    if (mathmlChild) {
      nsHTMLReflowMetrics childDesiredSize(aReflowState);
      // retrieve the metrics that was stored at the previous pass
      GetReflowAndBoundingMetricsFor(childFrame, childDesiredSize,
                                     childDesiredSize.mBoundingMetrics);
      
      mathmlChild->Stretch(*aReflowState.rendContext, 
                           stretchDir, containerSize, childDesiredSize);
      // store the updated metrics
      SaveReflowAndBoundingMetricsFor(childFrame, childDesiredSize,
                                      childDesiredSize.mBoundingMetrics);
      
      nscoord childDescent = childDesiredSize.Height() - childDesiredSize.BlockStartAscent();
      if (descent < childDescent)
        descent = childDescent;
//.........这里部分代码省略.........

//.........这里部分代码省略.........
        // XXX Need revisiting the width. TeX uses the exact width
        // e.g. in $$\huge\frac{\displaystyle\int}{i}$$
        nscoord width = std::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
        mContent->GetAttr(kNameSpaceID_None, 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
        mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::denomalign_, value);
        if (value.EqualsLiteral("left"))
            dxDen = leftSpace;
        else if (value.EqualsLiteral("right"))
            dxDen = width - rightSpace - sizeDen.Width();

        mBoundingMetrics.rightBearing =
            std::max(dxNum + bmNum.rightBearing, dxDen + bmDen.rightBearing);
        if (mBoundingMetrics.rightBearing < width - rightSpace)
            mBoundingMetrics.rightBearing = width - rightSpace;
        mBoundingMetrics.leftBearing =
            std::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.SetBlockStartAscent(sizeNum.BlockStartAscent() + numShift);
        aDesiredSize.Height() = aDesiredSize.BlockStartAscent() +
                                sizeDen.Height() - sizeDen.BlockStartAscent() + denShift;
        aDesiredSize.Width() = mBoundingMetrics.width;
        aDesiredSize.mBoundingMetrics = mBoundingMetrics;

        mReference.x = 0;
        mReference.y = aDesiredSize.BlockStartAscent();

        if (aPlaceOrigin) {
            nscoord dy;
            // place numerator
            dy = 0;
            FinishReflowChild(frameNum, presContext, sizeNum, nullptr, dxNum, dy, 0);
            // place denominator
            dy = aDesiredSize.Height() - sizeDen.Height();
            FinishReflowChild(frameDen, presContext, sizeDen, nullptr, dxDen, dy, 0);
            // place the fraction bar - dy is top of bar
            dy = aDesiredSize.BlockStartAscent() - (axisHeight + actualRuleThickness/2);
            mLineRect.SetRect(leftSpace, dy, width - (leftSpace + rightSpace),
                              actualRuleThickness);
        }
    } else {
        nscoord numShift = 0.0;
        nscoord denShift = 0.0;
        nscoord padding = 3 * defaultRuleThickness;
        nscoord slashRatio = 3;

        // Define the constant used in the expression of the maximum width
        nscoord em = fm->EmHeight();
        nscoord slashMaxWidthConstant = 2 * em;

        // For large line thicknesses the minimum slash height is limited to the

//.........这里部分代码省略.........

      // Update vertical parameters
      radicalAscent = bmBase.ascent + psi + mRadicalRuleThickness;
      radicalDescent = std::max(bmBase.descent,
                              (bmRadicalChar.ascent + bmRadicalChar.descent -
                               radicalAscent));

      mBoundingMetrics.ascent = std::max(mBoundingMetrics.ascent,
                                       radicalAscent);
      mBoundingMetrics.descent = std::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 = std::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 = std::min(0, dx_left + bmBase.leftBearing);
  mBoundingMetrics.rightBearing =
    std::max(mBoundingMetrics.width, dx_left + bmBase.rightBearing);
  
  aDesiredSize.Width() = mBoundingMetrics.width;

  aDesiredSize.SetBlockStartAscent(std::max(mBoundingMetrics.ascent,
                                            baseSize.BlockStartAscent()));
  aDesiredSize.Height() = aDesiredSize.BlockStartAscent() +
    std::max(mBoundingMetrics.descent,
             baseSize.Height() - baseSize.BlockStartAscent());

  if (IsToDraw(NOTATION_LONGDIV) || IsToDraw(NOTATION_RADICAL)) {
    nscoord desiredSizeAscent = aDesiredSize.BlockStartAscent();
    nscoord desiredSizeDescent = aDesiredSize.Height() -
                                 aDesiredSize.BlockStartAscent();
    
    if (IsToDraw(NOTATION_LONGDIV)) {
      desiredSizeAscent = std::max(desiredSizeAscent,
                                 longdivAscent + leading);
      desiredSizeDescent = std::max(desiredSizeDescent,
                                  longdivDescent + mRuleThickness);
    }
    
    if (IsToDraw(NOTATION_RADICAL)) {
      desiredSizeAscent = std::max(desiredSizeAscent,
                                 radicalAscent + leading);
      desiredSizeDescent = std::max(desiredSizeDescent,
                                    radicalDescent + mRadicalRuleThickness);
    }

    aDesiredSize.SetBlockStartAscent(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)

void
nsMathMLmtableOuterFrame::Reflow(nsPresContext*          aPresContext,
                                 nsHTMLReflowMetrics&     aDesiredSize,
                                 const nsHTMLReflowState& aReflowState,
                                 nsReflowStatus&          aStatus)
{
  nsAutoString value;
  // we want to return a table that is anchored according to the align attribute

  nsTableOuterFrame::Reflow(aPresContext, aDesiredSize, aReflowState, aStatus);
  NS_ASSERTION(aDesiredSize.Height() >= 0, "illegal height for mtable");
  NS_ASSERTION(aDesiredSize.Width() >= 0, "illegal width for mtable");

  // see if the user has set the align attribute on the <mtable>
  int32_t rowIndex = 0;
  eAlign tableAlign = eAlign_axis;
  mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::align, value);
  if (!value.IsEmpty()) {
    ParseAlignAttribute(value, tableAlign, rowIndex);
  }

  // adjustments if there is a specified row from where to anchor the table
  // (conceptually: when there is no row of reference, picture the table as if
  // it is wrapped in a single big fictional row at dy = 0, this way of
  // doing so allows us to have a single code path for all cases).
  nscoord dy = 0;
  WritingMode wm = aDesiredSize.GetWritingMode();
  nscoord blockSize = aDesiredSize.BSize(wm);
  nsIFrame* rowFrame = nullptr;
  if (rowIndex) {
    rowFrame = GetRowFrameAt(rowIndex);
    if (rowFrame) {
      // translate the coordinates to be relative to us and in our writing mode
      nsIFrame* frame = rowFrame;
      LogicalRect rect(wm, frame->GetRect(),
                       aReflowState.ComputedSizeAsContainerIfConstrained());
      blockSize = rect.BSize(wm);
      do {
        dy += rect.BStart(wm);
        frame = frame->GetParent();
      } while (frame != this);
    }
  }
  switch (tableAlign) {
    case eAlign_top:
      aDesiredSize.SetBlockStartAscent(dy);
      break;
    case eAlign_bottom:
      aDesiredSize.SetBlockStartAscent(dy + blockSize);
      break;
    case eAlign_center:
      aDesiredSize.SetBlockStartAscent(dy + blockSize / 2);
      break;
    case eAlign_baseline:
      if (rowFrame) {
        // anchor the table on the baseline of the row of reference
        nscoord rowAscent = ((nsTableRowFrame*)rowFrame)->GetMaxCellAscent();
        if (rowAscent) { // the row has at least one cell with 'vertical-align: baseline'
          aDesiredSize.SetBlockStartAscent(dy + rowAscent);
          break;
        }
      }
      // in other situations, fallback to center
      aDesiredSize.SetBlockStartAscent(dy + blockSize / 2);
      break;
    case eAlign_axis:
    default: {
      // XXX should instead use style data from the row of reference here ?
      RefPtr<nsFontMetrics> fm;
      nsLayoutUtils::GetFontMetricsForFrame(this, getter_AddRefs(fm),
                                            nsLayoutUtils::
                                            FontSizeInflationFor(this));
      nscoord axisHeight;
      GetAxisHeight(aReflowState.rendContext->GetDrawTarget(), fm, axisHeight);
      if (rowFrame) {
        // anchor the table on the axis of the row of reference
        // XXX fallback to baseline because it is a hard problem
        // XXX need to fetch the axis of the row; would need rowalign=axis to work better
        nscoord rowAscent = ((nsTableRowFrame*)rowFrame)->GetMaxCellAscent();
        if (rowAscent) { // the row has at least one cell with 'vertical-align: baseline'
          aDesiredSize.SetBlockStartAscent(dy + rowAscent);
          break;
        }
      }
      // in other situations, fallback to using half of the height
      aDesiredSize.SetBlockStartAscent(dy + blockSize / 2 + axisHeight);
    }
  }

  mReference.x = 0;
  mReference.y = aDesiredSize.BlockStartAscent();

  // just make-up a bounding metrics
  mBoundingMetrics = nsBoundingMetrics();
  mBoundingMetrics.ascent = aDesiredSize.BlockStartAscent();
  mBoundingMetrics.descent = aDesiredSize.Height() -
                             aDesiredSize.BlockStartAscent();
  mBoundingMetrics.width = aDesiredSize.Width();
  mBoundingMetrics.leftBearing = 0;
  mBoundingMetrics.rightBearing = aDesiredSize.Width();
//.........这里部分代码省略.........