static void AdjustRangeForSelection(nsIContent* aRoot,
                                    nsINode** aNode,
                                    PRInt32* aOffset)
{
  nsINode* node = *aNode;
  PRInt32 offset = *aOffset;
  if (aRoot != node && node->GetParent() &&
      !node->IsNodeOfType(nsINode::eTEXT)) {
    node = node->GetParent();
    offset = node->IndexOf(*aNode) + (offset ? 1 : 0);
  }
  
  nsIContent* brContent = node->GetChildAt(offset - 1);
  while (brContent && brContent->IsHTML()) {
    if (brContent->Tag() != nsGkAtoms::br || IsContentBR(brContent))
      break;
    brContent = node->GetChildAt(--offset - 1);
  }
  *aNode = node;
  *aOffset = NS_MAX(offset, 0);
}

PRBool
nsAttrValue::ParseIntWithBounds(const nsAString& aString,
                                PRInt32 aMin, PRInt32 aMax)
{
  NS_PRECONDITION(aMin < aMax, "bad boundaries");

  ResetIfSet();

  PRInt32 ec;
  PRBool strict;
  PRInt32 originalVal = StringToInteger(aString, &strict, &ec);
  if (NS_FAILED(ec)) {
    return PR_FALSE;
  }

  PRInt32 val = NS_MAX(originalVal, aMin);
  val = NS_MIN(val, aMax);
  strict = strict && (originalVal == val);
  SetIntValueAndType(val, eInteger, strict ? nsnull : &aString);

  return PR_TRUE;
}

nsresult
FileManager::Load(mozIStorageConnection* aConnection)
{
  NS_ASSERTION(!NS_IsMainThread(), "Wrong thread!");

  nsCOMPtr<mozIStorageStatement> stmt;
  nsresult rv = aConnection->CreateStatement(NS_LITERAL_CSTRING(
    "SELECT id, refcount "
    "FROM file"
  ), getter_AddRefs(stmt));
  NS_ENSURE_SUCCESS(rv, rv);

  bool hasResult;
  while (NS_SUCCEEDED(stmt->ExecuteStep(&hasResult)) && hasResult) {
    PRInt64 id;
    rv = stmt->GetInt64(0, &id);
    NS_ENSURE_SUCCESS(rv, rv);

    PRInt32 refcount;
    rv = stmt->GetInt32(1, &refcount);
    NS_ENSURE_SUCCESS(rv, rv);

    NS_ASSERTION(refcount, "This shouldn't happen!");

    nsRefPtr<FileInfo> fileInfo = FileInfo::Create(this, id);
    fileInfo->mDBRefCnt = refcount;

    if (!mFileInfos.Put(id, fileInfo)) {
      NS_WARNING("Out of memory?");
      return NS_ERROR_OUT_OF_MEMORY;
    }

    mLastFileId = NS_MAX(id, mLastFileId);
  }

  mLoaded = true;

  return NS_OK;
}

NS_IMETHODIMP
nsListBoxBodyFrame::DoLayout(nsBoxLayoutState& aBoxLayoutState)
{
  if (mScrolling)
    aBoxLayoutState.SetPaintingDisabled(true);

  nsresult rv = nsBoxFrame::DoLayout(aBoxLayoutState);

  // determine the real height for the scrollable area from the total number
  // of rows, since non-visible rows don't yet have frames
  nsRect rect(nsPoint(0, 0), GetSize());
  nsOverflowAreas overflow(rect, rect);
  if (mLayoutManager) {
    nsIFrame* childFrame = mFrames.FirstChild();
    while (childFrame) {
      ConsiderChildOverflow(overflow, childFrame);
      childFrame = childFrame->GetNextSibling();
    }

    nsSize prefSize = mLayoutManager->GetPrefSize(this, aBoxLayoutState);
    NS_FOR_FRAME_OVERFLOW_TYPES(otype) {
      nsRect& o = overflow.Overflow(otype);
      o.height = NS_MAX(o.height, prefSize.height);
    }
  }
  FinishAndStoreOverflow(overflow, GetSize());

  if (mScrolling)
    aBoxLayoutState.SetPaintingDisabled(false);

  // if we are scrolled and the row height changed
  // make sure we are scrolled to a correct index.
  if (mAdjustScroll)
     PostReflowCallback();

  return rv;
}

void
nsDOMWorkerTimeout::Suspend()
{
  AutoSpinlock lock(this);

  NS_ASSERTION(!IsSuspendedNoLock(), "Bad state!");

  mIsSuspended = PR_TRUE;
  mSuspendedRef = this;

  if (!mStarted) {
    mSuspendedBeforeStart = PR_TRUE;
    return;
  }

  mTimer->Cancel();

  mSuspendInterval = NS_MAX(0, PRInt32(mTargetTime - PR_Now())) /
                     (PRTime)PR_USEC_PER_MSEC;

  LOG(("Worker [0x%p] suspending timeout [0x%p] with id %u (interval = %u)",
       static_cast<void*>(mWorker.get()), static_cast<void*>(this), mId,
       mSuspendInterval));
}

// exported routine that both munder and msub share.
// munder uses this when movablelimits is set.
nsresult
nsMathMLmsubFrame::PlaceSubScript (nsPresContext*      aPresContext,
                                   nsRenderingContext& aRenderingContext,
                                   bool                 aPlaceOrigin,
                                   nsHTMLReflowMetrics& aDesiredSize,
                                   nsMathMLContainerFrame* aFrame,
                                   nscoord              aUserSubScriptShift,
                                   nscoord              aScriptSpace)
{
  // force the scriptSpace to be atleast 1 pixel 
  aScriptSpace = NS_MAX(nsPresContext::CSSPixelsToAppUnits(1), aScriptSpace);

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

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

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

  //////////////////
  // Place Children
  
  // get min subscript shift limit from x-height
  // = h(x) - 4/5 * sigma_5, Rule 18b, App. G, TeXbook
  nscoord xHeight = 0;
  nsRefPtr<nsFontMetrics> fm;
  nsLayoutUtils::GetFontMetricsForFrame(baseFrame, getter_AddRefs(fm));

  xHeight = fm->XHeight();
  nscoord minShiftFromXHeight = (nscoord) 
    (bmSubScript.ascent - (4.0f/5.0f) * xHeight);

  // subScriptShift
  // = minimum amount to shift the subscript down set by user or from the font
  // = sub1 in TeX
  // = subscriptshift attribute * x-height
  nscoord subScriptShift, dummy;
  // get subScriptShift default from font
  GetSubScriptShifts (fm, subScriptShift, dummy);

  subScriptShift = 
    NS_MAX(subScriptShift, aUserSubScriptShift);

  // get actual subscriptshift to be used
  // Rule 18b, App. G, TeXbook
  nscoord actualSubScriptShift = 
    NS_MAX(minSubScriptShift,NS_MAX(subScriptShift,minShiftFromXHeight));
  // get bounding box for base + subscript
  nsBoundingMetrics boundingMetrics;
  boundingMetrics.ascent = 
    NS_MAX(bmBase.ascent, bmSubScript.ascent - actualSubScriptShift);
  boundingMetrics.descent = 
    NS_MAX(bmBase.descent, bmSubScript.descent + actualSubScriptShift);

  // add aScriptSpace to the subscript's width
  boundingMetrics.width = bmBase.width + bmSubScript.width + aScriptSpace;
  boundingMetrics.leftBearing = bmBase.leftBearing;
  boundingMetrics.rightBearing = NS_MAX(bmBase.rightBearing, bmBase.width +
    NS_MAX(bmSubScript.width + aScriptSpace, bmSubScript.rightBearing));
  aFrame->SetBoundingMetrics (boundingMetrics);

  // reflow metrics
  aDesiredSize.ascent = 
    NS_MAX(baseSize.ascent, subScriptSize.ascent - actualSubScriptShift);
  aDesiredSize.height = aDesiredSize.ascent +
    NS_MAX(baseSize.height - baseSize.ascent,
           subScriptSize.height - subScriptSize.ascent + actualSubScriptShift);
  aDesiredSize.width = boundingMetrics.width;
  aDesiredSize.mBoundingMetrics = boundingMetrics;

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

  if (aPlaceOrigin) {
    nscoord dx, dy;
    // now place the base ...
    dx = aFrame->MirrorIfRTL(aDesiredSize.width, baseSize.width, 0);
    dy = aDesiredSize.ascent - baseSize.ascent;
    FinishReflowChild (baseFrame, aPresContext, nullptr, baseSize, dx, dy, 0);
    // ... and subscript
//.........这里部分代码省略.........

float Axis::GetAccelerationFactor() {
  return powf(ACCELERATION_MULTIPLIER, NS_MAX(0, (mAcceleration - 4) * 3));
}

//.........这里部分代码省略.........
    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;

  // height(radical) should be >= height(base) + psi + ruleThickness
  nsBoundingMetrics radicalSize;
  mSqrChar.Stretch(aPresContext, renderingContext,
                   NS_STRETCH_DIRECTION_VERTICAL, 
                   contSize, radicalSize,
                   NS_STRETCH_LARGER);
  // radicalSize have changed at this point, and should match with
  // the bounding metrics of the char
  mSqrChar.GetBoundingMetrics(bmSqr);

  // Update the desired size for the container (like msqrt, index is not yet included)
  // the baseline will be that of the base.
  mBoundingMetrics.ascent = bmBase.ascent + psi + ruleThickness;
  mBoundingMetrics.descent = 
    NS_MAX(bmBase.descent,
           (bmSqr.ascent + bmSqr.descent - mBoundingMetrics.ascent));
  mBoundingMetrics.width = bmSqr.width + bmBase.width;
  mBoundingMetrics.leftBearing = bmSqr.leftBearing;
  mBoundingMetrics.rightBearing = bmSqr.width + 
    NS_MAX(bmBase.width, bmBase.rightBearing); // take also care of the rule

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

  /////////////
  // Re-adjust the desired size to include the index.
  
  // the index is raised by some fraction of the height
  // of the radical, see \mroot macro in App. B, TexBook
  nscoord raiseIndexDelta = NSToCoordRound(0.6f * (bmSqr.ascent + bmSqr.descent));
  nscoord indexRaisedAscent = mBoundingMetrics.ascent // top of radical 
    - (bmSqr.ascent + bmSqr.descent) // to bottom of radical
    + raiseIndexDelta + bmIndex.ascent + bmIndex.descent; // to top of raised index

  nscoord indexClearance = 0;
  if (mBoundingMetrics.ascent < indexRaisedAscent) {
    indexClearance = 
      indexRaisedAscent - mBoundingMetrics.ascent; // excess gap introduced by a tall index 
    mBoundingMetrics.ascent = indexRaisedAscent;
    nscoord descent = aDesiredSize.height - aDesiredSize.ascent;
    aDesiredSize.ascent = mBoundingMetrics.ascent + leading;
    aDesiredSize.height = aDesiredSize.ascent + descent;
  }

nsSize
nsBox::BoundsCheckMinMax(const nsSize& aMinSize, const nsSize& aMaxSize)
{
  return nsSize(NS_MAX(aMaxSize.width, aMinSize.width),
                NS_MAX(aMaxSize.height, aMinSize.height));
}

//.........这里部分代码省略.........
    }

    aMetrics->zeroOrAveCharWidth = 0.0;
    if (GetCharExtents('0', &extents)) {
        aMetrics->zeroOrAveCharWidth = extents.x_advance;
    }

    // Prefering a measured x over sxHeight because sxHeight doesn't consider
    // hinting, but maybe the x extents are not quite right in some fancy
    // script fonts.  CSS 2.1 suggests possibly using the height of an "o",
    // which would have a more consistent glyph across fonts.
    if (GetCharExtents('x', &extents) && extents.y_bearing < 0.0) {
        aMetrics->xHeight = -extents.y_bearing;
        aMetrics->aveCharWidth = extents.x_advance;
    } else {
        if (os2 && os2->sxHeight) {
            aMetrics->xHeight = os2->sxHeight * yScale;
        } else {
            // CSS 2.1, section 4.3.2 Lengths: "In the cases where it is
            // impossible or impractical to determine the x-height, a value of
            // 0.5em should be used."
            aMetrics->xHeight = 0.5 * emHeight;
        }
        aMetrics->aveCharWidth = 0.0; // updated below
    }
    // aveCharWidth is used for the width of text input elements so be
    // liberal rather than conservative in the estimate.
    if (os2 && os2->xAvgCharWidth) {
        // Round to pixels as this is compared with maxAdvance to guess
        // whether this is a fixed width font.
        gfxFloat avgCharWidth =
            ScaleRoundDesignUnits(os2->xAvgCharWidth, ftMetrics.x_scale);
        aMetrics->aveCharWidth =
            NS_MAX(aMetrics->aveCharWidth, avgCharWidth);
    }
    aMetrics->aveCharWidth =
        NS_MAX(aMetrics->aveCharWidth, aMetrics->zeroOrAveCharWidth);
    if (aMetrics->aveCharWidth == 0.0) {
        aMetrics->aveCharWidth = aMetrics->spaceWidth;
    }
    if (aMetrics->zeroOrAveCharWidth == 0.0) {
        aMetrics->zeroOrAveCharWidth = aMetrics->aveCharWidth;
    }
    // Apparently hinting can mean that max_advance is not always accurate.
    aMetrics->maxAdvance =
        NS_MAX(aMetrics->maxAdvance, aMetrics->aveCharWidth);

    // gfxFont::Metrics::underlineOffset is the position of the top of the
    // underline.
    //
    // FT_FaceRec documentation describes underline_position as "the
    // center of the underlining stem".  This was the original definition
    // of the PostScript metric, but in the PostScript table of OpenType
    // fonts the metric is "the top of the underline"
    // (http://www.microsoft.com/typography/otspec/post.htm), and FreeType
    // (up to version 2.3.7) doesn't make any adjustment.
    //
    // Therefore get the underline position directly from the table
    // ourselves when this table exists.  Use FreeType's metrics for
    // other (including older PostScript) fonts.
    if (mFace->underline_position && mFace->underline_thickness) {
        aMetrics->underlineSize = mFace->underline_thickness * yScale;
        TT_Postscript *post = static_cast<TT_Postscript*>
            (FT_Get_Sfnt_Table(mFace, ft_sfnt_post));
        if (post && post->underlinePosition) {
            aMetrics->underlineOffset = post->underlinePosition * yScale;

//.........这里部分代码省略.........
  while (childFrame) {
    nsIMathMLFrame* mathmlChild = do_QueryFrame(childFrame);
    if (mathmlChild) {
      nsHTMLReflowMetrics childDesiredSize;
      // 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.ascent;
      if (descent < childDescent)
        descent = childDescent;
      if (ascent < childDesiredSize.ascent)
        ascent = childDesiredSize.ascent;
    }
    childFrame = childFrame->GetNextSibling();
  }

  // bug 121748: for surrounding fences & separators, use a size that covers everything
  GetPreferredStretchSize(*aReflowState.rendContext,
                          STRETCH_CONSIDER_EMBELLISHMENTS,
                          stretchDir, containerSize);

  //////////////////////////////////////////
  // Prepare the opening fence, separators, and closing fence, and
  // adjust the origin of children.

  // we need to center around the axis
  nscoord delta = NS_MAX(containerSize.ascent - axisHeight, 
                         containerSize.descent + axisHeight);
  containerSize.ascent = delta + axisHeight;
  containerSize.descent = delta - axisHeight;

  /////////////////
  // opening fence ...
  ReflowChar(aPresContext, *aReflowState.rendContext, mOpenChar,
             NS_MATHML_OPERATOR_FORM_PREFIX, font->mScriptLevel, 
             axisHeight, leading, em, containerSize, ascent, descent);
  /////////////////
  // separators ...
  for (i = 0; i < mSeparatorsCount; i++) {
    ReflowChar(aPresContext, *aReflowState.rendContext, &mSeparatorsChar[i],
               NS_MATHML_OPERATOR_FORM_INFIX, font->mScriptLevel,
               axisHeight, leading, em, containerSize, ascent, descent);
  }
  /////////////////
  // closing fence ...
  ReflowChar(aPresContext, *aReflowState.rendContext, mCloseChar,
             NS_MATHML_OPERATOR_FORM_POSTFIX, font->mScriptLevel,
             axisHeight, leading, em, containerSize, ascent, descent);

  //////////////////
  // Adjust the origins of each child.
  // and update our bounding metrics

  i = 0;
  nscoord dx = 0;
  nsBoundingMetrics bm;
  PRBool firstTime = PR_TRUE;
  if (mOpenChar) {
    PlaceChar(mOpenChar, ascent, bm, dx);

//.........这里部分代码省略.........
       //XXX we don't handle splitting frames for inline absolute containing blocks yet
    && (aKidFrame->GetRect().y <= aReflowState.availableHeight);
       // Don't split things below the fold. (Ideally we shouldn't *have*
       // anything totally below the fold, but we can't position frames
       // across next-in-flow breaks yet.
  if (constrainHeight) {
    kidReflowState.availableHeight = aReflowState.availableHeight - border.top
                                     - kidReflowState.mComputedMargin.top;
    if (NS_AUTOOFFSET != kidReflowState.mComputedOffsets.top)
      kidReflowState.availableHeight -= kidReflowState.mComputedOffsets.top;
  }

  // Do the reflow
  rv = aKidFrame->Reflow(aPresContext, kidDesiredSize, kidReflowState, aStatus);

  // If we're solving for 'left' or 'top', then compute it now that we know the
  // width/height
  if ((NS_AUTOOFFSET == kidReflowState.mComputedOffsets.left) ||
      (NS_AUTOOFFSET == kidReflowState.mComputedOffsets.top)) {
    if (-1 == aContainingBlockWidth) {
      // Get the containing block width/height
      kidReflowState.ComputeContainingBlockRectangle(aPresContext,
                                                     &aReflowState,
                                                     aContainingBlockWidth,
                                                     aContainingBlockHeight);
    }

    if (NS_AUTOOFFSET == kidReflowState.mComputedOffsets.left) {
      NS_ASSERTION(NS_AUTOOFFSET != kidReflowState.mComputedOffsets.right,
                   "Can't solve for both left and right");
      kidReflowState.mComputedOffsets.left = aContainingBlockWidth -
                                             kidReflowState.mComputedOffsets.right -
                                             kidReflowState.mComputedMargin.right -
                                             kidDesiredSize.width -
                                             kidReflowState.mComputedMargin.left;
    }
    if (NS_AUTOOFFSET == kidReflowState.mComputedOffsets.top) {
      kidReflowState.mComputedOffsets.top = aContainingBlockHeight -
                                            kidReflowState.mComputedOffsets.bottom -
                                            kidReflowState.mComputedMargin.bottom -
                                            kidDesiredSize.height -
                                            kidReflowState.mComputedMargin.top;
    }
  }

  // Position the child relative to our padding edge
  nsRect  rect(border.left + kidReflowState.mComputedOffsets.left + kidReflowState.mComputedMargin.left,
               border.top + kidReflowState.mComputedOffsets.top + kidReflowState.mComputedMargin.top,
               kidDesiredSize.width, kidDesiredSize.height);
  aKidFrame->SetRect(rect);

  nsIView* view = aKidFrame->GetView();
  if (view) {
    // Size and position the view and set its opacity, visibility, content
    // transparency, and clip
    nsContainerFrame::SyncFrameViewAfterReflow(aPresContext, aKidFrame, view,
                                               kidDesiredSize.VisualOverflow());
  } else {
    nsContainerFrame::PositionChildViews(aKidFrame);
  }

  if (oldRect.TopLeft() != rect.TopLeft() || 
      (aDelegatingFrame->GetStateBits() & NS_FRAME_FIRST_REFLOW)) {
    // The frame moved
    aKidFrame->GetParent()->Invalidate(oldOverflowRect);
    aKidFrame->InvalidateFrameSubtree();
  } else if (oldRect.Size() != rect.Size()) {
    // Invalidate the area where the frame changed size.
    nscoord innerWidth = NS_MIN(oldRect.width, rect.width);
    nscoord innerHeight = NS_MIN(oldRect.height, rect.height);
    nscoord outerWidth = NS_MAX(oldRect.width, rect.width);
    nscoord outerHeight = NS_MAX(oldRect.height, rect.height);
    aKidFrame->GetParent()->Invalidate(
        nsRect(rect.x + innerWidth, rect.y, outerWidth - innerWidth, outerHeight));
    // Invalidate the horizontal strip
    aKidFrame->GetParent()->Invalidate(
        nsRect(rect.x, rect.y + innerHeight, outerWidth, outerHeight - innerHeight));
  }
  aKidFrame->DidReflow(aPresContext, &kidReflowState, NS_FRAME_REFLOW_FINISHED);

#ifdef DEBUG
  if (nsBlockFrame::gNoisyReflow) {
    nsFrame::IndentBy(stdout,nsBlockFrame::gNoiseIndent - 1);
    printf("abs pos ");
    if (aKidFrame) {
      nsAutoString name;
      aKidFrame->GetFrameName(name);
      printf("%s ", NS_LossyConvertUTF16toASCII(name).get());
    }
    printf("%p rect=%d,%d,%d,%d\n", static_cast<void*>(aKidFrame),
           rect.x, rect.y, rect.width, rect.height);
  }
#endif

  if (aOverflowAreas) {
    aOverflowAreas->UnionWith(kidDesiredSize.mOverflowAreas + rect.TopLeft());
  }

  return rv;
}

/* 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 
//.........这里部分代码省略.........

nsresult
FileManager::Init(nsIFile* aDirectory,
                  mozIStorageConnection* aConnection)
{
  NS_ASSERTION(!NS_IsMainThread(), "Wrong thread!");
  NS_ASSERTION(aDirectory, "Null directory!");
  NS_ASSERTION(aConnection, "Null connection!");

  mFileInfos.Init();

  bool exists;
  nsresult rv = aDirectory->Exists(&exists);
  NS_ENSURE_SUCCESS(rv, rv);

  if (exists) {
    bool isDirectory;
    rv = aDirectory->IsDirectory(&isDirectory);
    NS_ENSURE_SUCCESS(rv, rv);
    NS_ENSURE_TRUE(isDirectory, NS_ERROR_FAILURE);
  }
  else {
    rv = aDirectory->Create(nsIFile::DIRECTORY_TYPE, 0755);
    NS_ENSURE_SUCCESS(rv, rv);
  }

  rv = aDirectory->GetPath(mDirectoryPath);
  NS_ENSURE_SUCCESS(rv, rv);

  nsCOMPtr<nsIFile> journalDirectory;
  rv = aDirectory->Clone(getter_AddRefs(journalDirectory));
  NS_ENSURE_SUCCESS(rv, rv);

  rv = journalDirectory->Append(NS_LITERAL_STRING(JOURNAL_DIRECTORY_NAME));
  NS_ENSURE_SUCCESS(rv, rv);

  rv = journalDirectory->Exists(&exists);
  NS_ENSURE_SUCCESS(rv, rv);

  if (exists) {
    bool isDirectory;
    rv = journalDirectory->IsDirectory(&isDirectory);
    NS_ENSURE_SUCCESS(rv, rv);
    NS_ENSURE_TRUE(isDirectory, NS_ERROR_FAILURE);
  }

  rv = journalDirectory->GetPath(mJournalDirectoryPath);
  NS_ENSURE_SUCCESS(rv, rv);

  nsCOMPtr<mozIStorageStatement> stmt;
  rv = aConnection->CreateStatement(NS_LITERAL_CSTRING(
    "SELECT id, refcount "
    "FROM file"
  ), getter_AddRefs(stmt));
  NS_ENSURE_SUCCESS(rv, rv);

  bool hasResult;
  while (NS_SUCCEEDED(stmt->ExecuteStep(&hasResult)) && hasResult) {
    int64_t id;
    rv = stmt->GetInt64(0, &id);
    NS_ENSURE_SUCCESS(rv, rv);

    int32_t refcount;
    rv = stmt->GetInt32(1, &refcount);
    NS_ENSURE_SUCCESS(rv, rv);

    NS_ASSERTION(refcount, "This shouldn't happen!");

    nsRefPtr<FileInfo> fileInfo = FileInfo::Create(this, id);
    fileInfo->mDBRefCnt = refcount;

    mFileInfos.Put(id, fileInfo);

    mLastFileId = NS_MAX(id, mLastFileId);
  }

  return NS_OK;
}

static void
InflateRight(nsRect* aRect, nscoord aDelta)
{
  aRect->width = NS_MAX(aRect->width + aDelta, 0);
}

float Axis::GetAccelerationFactor() {
    return powf(gAccelerationMultiplier, NS_MAX(0, (mAcceleration - 4) * 3));
}

// exported routine that both munderover and msubsup share.
// munderover uses this when movablelimits is set.
nsresult
nsMathMLmsubsupFrame::PlaceSubSupScript(nsPresContext*      aPresContext,
                                        nsRenderingContext& 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 = NS_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->GetFirstPrincipalChild();
  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;

  nsRefPtr<nsFontMetrics> fm;
  nsLayoutUtils::GetFontMetricsForFrame(baseFrame, getter_AddRefs(fm));
  aRenderingContext.SetFont(fm);

  // get x-height (an ex)
  nscoord xHeight = fm->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 = NS_MAX(subScriptShift1, aUserSubScriptShift);
    subScriptShift2 = NSToCoordRound(scaler * subScriptShift1);
  }

  // get a tentative value for subscriptshift
  // Rule 18d, App. G, TeXbook
  nscoord subScriptShift =
    NS_MAX(minSubScriptShift,NS_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);
//.........这里部分代码省略.........

/**
 * Box blur involves looking at one pixel, and setting its value to the average
 * of its neighbouring pixels.
 * @param aInput The input buffer.
 * @param aOutput The output buffer.
 * @param aLeftLobe The number of pixels to blend on the left.
 * @param aRightLobe The number of pixels to blend on the right.
 * @param aWidth The number of columns in the buffers.
 * @param aRows The number of rows in the buffers.
 * @param aSkipRect An area to skip blurring in.
 * XXX shouldn't we pass stride in separately here?
 */
static void
BoxBlurHorizontal(unsigned char* aInput,
                  unsigned char* aOutput,
                  PRInt32 aLeftLobe,
                  PRInt32 aRightLobe,
                  PRInt32 aWidth,
                  PRInt32 aRows,
                  const nsIntRect& aSkipRect)
{
    NS_ASSERTION(aWidth > 0, "Can't handle zero width here");

    PRInt32 boxSize = aLeftLobe + aRightLobe + 1;
    PRBool skipRectCoversWholeRow = 0 >= aSkipRect.x &&
                                    aWidth <= aSkipRect.XMost();

    for (PRInt32 y = 0; y < aRows; y++) {
        // Check whether the skip rect intersects this row. If the skip
        // rect covers the whole surface in this row, we can avoid
        // this row entirely (and any others along the skip rect).
        PRBool inSkipRectY = y >= aSkipRect.y &&
                             y < aSkipRect.YMost();
        if (inSkipRectY && skipRectCoversWholeRow) {
            y = aSkipRect.YMost() - 1;
            continue;
        }

        PRInt32 alphaSum = 0;
        for (PRInt32 i = 0; i < boxSize; i++) {
            PRInt32 pos = i - aLeftLobe;
            // See assertion above; if aWidth is zero, then we would have no
            // valid position to clamp to.
            pos = NS_MAX(pos, 0);
            pos = NS_MIN(pos, aWidth - 1);
            alphaSum += aInput[aWidth * y + pos];
        }
        for (PRInt32 x = 0; x < aWidth; x++) {
            // Check whether we are within the skip rect. If so, go
            // to the next point outside the skip rect.
            if (inSkipRectY && x >= aSkipRect.x &&
                x < aSkipRect.XMost()) {
                x = aSkipRect.XMost();
                if (x >= aWidth)
                    break;

                // Recalculate the neighbouring alpha values for
                // our new point on the surface.
                alphaSum = 0;
                for (PRInt32 i = 0; i < boxSize; i++) {
                    PRInt32 pos = x + i - aLeftLobe;
                    // See assertion above; if aWidth is zero, then we would have no
                    // valid position to clamp to.
                    pos = NS_MAX(pos, 0);
                    pos = NS_MIN(pos, aWidth - 1);
                    alphaSum += aInput[aWidth * y + pos];
                }
            }
            PRInt32 tmp = x - aLeftLobe;
            PRInt32 last = NS_MAX(tmp, 0);
            PRInt32 next = NS_MIN(tmp + boxSize, aWidth - 1);

            aOutput[aWidth * y + x] = alphaSum/boxSize;

            alphaSum += aInput[aWidth * y + next] -
                        aInput[aWidth * y + last];
        }
    }
}

nsresult 
nsTableOuterFrame::GetCaptionOrigin(PRUint32         aCaptionSide,
                                    const nsSize&    aContainBlockSize,
                                    const nsSize&    aInnerSize, 
                                    const nsMargin&  aInnerMargin,
                                    const nsSize&    aCaptionSize,
                                    nsMargin&        aCaptionMargin,
                                    nsPoint&         aOrigin)
{
  aOrigin.x = aOrigin.y = 0;
  if ((NS_UNCONSTRAINEDSIZE == aInnerSize.width) || (NS_UNCONSTRAINEDSIZE == aInnerSize.height) ||  
      (NS_UNCONSTRAINEDSIZE == aCaptionSize.width) || (NS_UNCONSTRAINEDSIZE == aCaptionSize.height)) {
    return NS_OK;
  }
  if (mCaptionFrames.IsEmpty()) return NS_OK;
  
  NS_ASSERTION(NS_AUTOMARGIN != aCaptionMargin.left,   "The computed caption margin is auto?");
  NS_ASSERTION(NS_AUTOMARGIN != aCaptionMargin.top,    "The computed caption margin is auto?");
  NS_ASSERTION(NS_AUTOMARGIN != aCaptionMargin.bottom, "The computed caption margin is auto?");

  // horizontal computation
  switch(aCaptionSide) {
  case NS_STYLE_CAPTION_SIDE_BOTTOM:
  case NS_STYLE_CAPTION_SIDE_BOTTOM_OUTSIDE: {
    // FIXME: Position relative to right edge for RTL.  (Based on table
    // direction or table parent direction?)
    aOrigin.x = aCaptionMargin.left;
    if (aCaptionSide == NS_STYLE_CAPTION_SIDE_BOTTOM) {
      // We placed the caption using only the table's width as available
      // width, and we should position it this way as well.
      aOrigin.x