C++ nsHTMLReflowState::CalcLineHeight方法代码示例

//.........这里部分代码省略.........
    mFloatBreakType(NS_STYLE_CLEAR_NONE),
    mConsumedBSize(aConsumedBSize)
{
  if (!sFloatFragmentsInsideColumnPrefCached) {
    sFloatFragmentsInsideColumnPrefCached = true;
    Preferences::AddBoolVarCache(&sFloatFragmentsInsideColumnEnabled,
                                 "layout.float-fragments-inside-column.enabled");
  }
  SetFlag(BRS_FLOAT_FRAGMENTS_INSIDE_COLUMN_ENABLED, sFloatFragmentsInsideColumnEnabled);
  
  WritingMode wm = aReflowState.GetWritingMode();
  SetFlag(BRS_ISFIRSTINFLOW, aFrame->GetPrevInFlow() == nullptr);
  SetFlag(BRS_ISOVERFLOWCONTAINER, IS_TRUE_OVERFLOW_CONTAINER(aFrame));

  nsIFrame::LogicalSides logicalSkipSides =
    aFrame->GetLogicalSkipSides(&aReflowState);
  mBorderPadding.ApplySkipSides(logicalSkipSides);

  // Note that mContainerSize is the physical size, needed to
  // convert logical block-coordinates in vertical-rl writing mode
  // (measured from a RHS origin) to physical coordinates within the
  // containing block.
  // If aReflowState doesn't have a constrained ComputedWidth(), we set
  // mContainerSize.width to zero, which means lines will be positioned
  // (physically) incorrectly; we will fix them up at the end of
  // nsBlockFrame::Reflow, after we know the total block-size of the
  // frame.
  mContainerSize.width = aReflowState.ComputedWidth();
  if (mContainerSize.width == NS_UNCONSTRAINEDSIZE) {
    mContainerSize.width = 0;
  }

  mContainerSize.width += mBorderPadding.LeftRight(wm);

  // For now at least, we don't do that fix-up for mContainerHeight.
  // It's only used in nsBidiUtils::ReorderFrames for vertical rtl
  // writing modes, which aren't fully supported for the time being.
  mContainerSize.height = aReflowState.ComputedHeight() +
                          mBorderPadding.TopBottom(wm);

  if ((aBStartMarginRoot && !logicalSkipSides.BStart()) ||
      0 != mBorderPadding.BStart(wm)) {
    SetFlag(BRS_ISBSTARTMARGINROOT, true);
    SetFlag(BRS_APPLYBSTARTMARGIN, true);
  }
  if ((aBEndMarginRoot && !logicalSkipSides.BEnd()) ||
      0 != mBorderPadding.BEnd(wm)) {
    SetFlag(BRS_ISBENDMARGINROOT, true);
  }
  if (aBlockNeedsFloatManager) {
    SetFlag(BRS_FLOAT_MGR, true);
  }
  
  mFloatManager = aReflowState.mFloatManager;

  NS_ASSERTION(mFloatManager,
               "FloatManager should be set in nsBlockReflowState" );
  if (mFloatManager) {
    // Save the coordinate system origin for later.
    mFloatManager->GetTranslation(mFloatManagerI, mFloatManagerB);
    mFloatManager->PushState(&mFloatManagerStateBefore); // never popped
  }

  mReflowStatus = NS_FRAME_COMPLETE;

  mNextInFlow = static_cast<nsBlockFrame*>(mBlock->GetNextInFlow());

  LAYOUT_WARN_IF_FALSE(NS_UNCONSTRAINEDSIZE != aReflowState.ComputedISize(),
                       "have unconstrained width; this should only result "
                       "from very large sizes, not attempts at intrinsic "
                       "width calculation");
  mContentArea.ISize(wm) = aReflowState.ComputedISize();

  // Compute content area height. Unlike the width, if we have a
  // specified style height we ignore it since extra content is
  // managed by the "overflow" property. When we don't have a
  // specified style height then we may end up limiting our height if
  // the availableHeight is constrained (this situation occurs when we
  // are paginated).
  if (NS_UNCONSTRAINEDSIZE != aReflowState.AvailableBSize()) {
    // We are in a paginated situation. The bottom edge is just inside
    // the bottom border and padding. The content area height doesn't
    // include either border or padding edge.
    mBEndEdge = aReflowState.AvailableBSize() - mBorderPadding.BEnd(wm);
    mContentArea.BSize(wm) = std::max(0, mBEndEdge - mBorderPadding.BStart(wm));
  }
  else {
    // When we are not in a paginated situation then we always use
    // an constrained height.
    SetFlag(BRS_UNCONSTRAINEDBSIZE, true);
    mContentArea.BSize(wm) = mBEndEdge = NS_UNCONSTRAINEDSIZE;
  }
  mContentArea.IStart(wm) = mBorderPadding.IStart(wm);
  mBCoord = mContentArea.BStart(wm) = mBorderPadding.BStart(wm);

  mPrevChild = nullptr;
  mCurrentLine = aFrame->end_lines();

  mMinLineHeight = aReflowState.CalcLineHeight();
}

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);
}

nsBlockReflowState::nsBlockReflowState(const nsHTMLReflowState& aReflowState,
                                       nsPresContext* aPresContext,
                                       nsBlockFrame* aFrame,
                                       const nsHTMLReflowMetrics& aMetrics,
                                       bool aTopMarginRoot,
                                       bool aBottomMarginRoot,
                                       bool aBlockNeedsFloatManager)
  : mBlock(aFrame),
    mPresContext(aPresContext),
    mReflowState(aReflowState),
    mPushedFloats(nsnull),
    mOverflowTracker(nsnull),
    mPrevBottomMargin(),
    mLineNumber(0),
    mFlags(0),
    mFloatBreakType(NS_STYLE_CLEAR_NONE)
{
  SetFlag(BRS_ISFIRSTINFLOW, aFrame->GetPrevInFlow() == nsnull);
  SetFlag(BRS_ISOVERFLOWCONTAINER,
          IS_TRUE_OVERFLOW_CONTAINER(aFrame));

  const nsMargin& borderPadding = BorderPadding();

  if (aTopMarginRoot || 0 != aReflowState.mComputedBorderPadding.top) {
    SetFlag(BRS_ISTOPMARGINROOT, true);
  }
  if (aBottomMarginRoot || 0 != aReflowState.mComputedBorderPadding.bottom) {
    SetFlag(BRS_ISBOTTOMMARGINROOT, true);
  }
  if (GetFlag(BRS_ISTOPMARGINROOT)) {
    SetFlag(BRS_APPLYTOPMARGIN, true);
  }
  if (aBlockNeedsFloatManager) {
    SetFlag(BRS_FLOAT_MGR, true);
  }
  
  mFloatManager = aReflowState.mFloatManager;

  NS_ASSERTION(mFloatManager,
               "FloatManager should be set in nsBlockReflowState" );
  if (mFloatManager) {
    // Save the coordinate system origin for later.
    mFloatManager->GetTranslation(mFloatManagerX, mFloatManagerY);
    mFloatManager->PushState(&mFloatManagerStateBefore); // never popped
  }

  mReflowStatus = NS_FRAME_COMPLETE;

  mPresContext = aPresContext;
  mNextInFlow = static_cast<nsBlockFrame*>(mBlock->GetNextInFlow());

  NS_WARN_IF_FALSE(NS_UNCONSTRAINEDSIZE != aReflowState.ComputedWidth(),
                   "have unconstrained width; this should only result from "
                   "very large sizes, not attempts at intrinsic width "
                   "calculation");
  mContentArea.width = aReflowState.ComputedWidth();

  // Compute content area height. Unlike the width, if we have a
  // specified style height we ignore it since extra content is
  // managed by the "overflow" property. When we don't have a
  // specified style height then we may end up limiting our height if
  // the availableHeight is constrained (this situation occurs when we
  // are paginated).
  if (NS_UNCONSTRAINEDSIZE != aReflowState.availableHeight) {
    // We are in a paginated situation. The bottom edge is just inside
    // the bottom border and padding. The content area height doesn't
    // include either border or padding edge.
    mBottomEdge = aReflowState.availableHeight - borderPadding.bottom;
    mContentArea.height = NS_MAX(0, mBottomEdge - borderPadding.top);
  }
  else {
    // When we are not in a paginated situation then we always use
    // an constrained height.
    SetFlag(BRS_UNCONSTRAINEDHEIGHT, true);
    mContentArea.height = mBottomEdge = NS_UNCONSTRAINEDSIZE;
  }
  mContentArea.x = borderPadding.left;
  mY = mContentArea.y = borderPadding.top;

  mPrevChild = nsnull;
  mCurrentLine = aFrame->end_lines();

  mMinLineHeight = aReflowState.CalcLineHeight();
}