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

nsresult
nsComboboxControlFrame::ReflowDropdown(nsPresContext*  aPresContext, 
                                       const nsHTMLReflowState& aReflowState)
{
  // All we want out of it later on, really, is the height of a row, so we
  // don't even need to cache mDropdownFrame's ascent or anything.  If we don't
  // need to reflow it, just bail out here.
  if (!aReflowState.ShouldReflowAllKids() &&
      !NS_SUBTREE_DIRTY(mDropdownFrame)) {
    return NS_OK;
  }

  // XXXbz this will, for small-height dropdowns, have extra space on the right
  // edge for the scrollbar we don't show... but that's the best we can do here
  // for now.
  nsSize availSize(aReflowState.availableWidth, NS_UNCONSTRAINEDSIZE);
  nsHTMLReflowState kidReflowState(aPresContext, aReflowState, mDropdownFrame,
                                   availSize);

  // If the dropdown's intrinsic width is narrower than our specified width,
  // then expand it out.  We want our border-box width to end up the same as
  // the dropdown's so account for both sets of mComputedBorderPadding.
  nscoord forcedWidth = aReflowState.ComputedWidth() +
    aReflowState.mComputedBorderPadding.LeftRight() -
    kidReflowState.mComputedBorderPadding.LeftRight();
  kidReflowState.SetComputedWidth(PR_MAX(kidReflowState.ComputedWidth(),
                                         forcedWidth));

  // ensure we start off hidden
  if (GetStateBits() & NS_FRAME_FIRST_REFLOW) {
    nsIView* view = mDropdownFrame->GetView();
    nsIViewManager* viewManager = view->GetViewManager();
    viewManager->SetViewVisibility(view, nsViewVisibility_kHide);
    nsRect emptyRect(0, 0, 0, 0);
    viewManager->ResizeView(view, emptyRect);
  }
  
  // Allow the child to move/size/change-visibility its view if it's currently
  // dropped down
  PRInt32 flags = NS_FRAME_NO_MOVE_FRAME | NS_FRAME_NO_VISIBILITY | NS_FRAME_NO_SIZE_VIEW;
  if (mDroppedDown) {
    flags = 0;
  }
  nsRect rect = mDropdownFrame->GetRect();
  nsHTMLReflowMetrics desiredSize;
  nsReflowStatus ignoredStatus;
  nsresult rv = ReflowChild(mDropdownFrame, aPresContext, desiredSize,
                            kidReflowState, rect.x, rect.y, flags,
                            ignoredStatus);
 
   // Set the child's width and height to it's desired size
  FinishReflowChild(mDropdownFrame, aPresContext, &kidReflowState,
                    desiredSize, rect.x, rect.y, flags);
  return rv;
}

void
nsAbsoluteContainingBlock::Reflow(nsContainerFrame*        aDelegatingFrame,
                                  nsPresContext*           aPresContext,
                                  const nsHTMLReflowState& aReflowState,
                                  nsReflowStatus&          aReflowStatus,
                                  const nsRect&            aContainingBlock,
                                  AbsPosReflowFlags        aFlags,
                                  nsOverflowAreas*         aOverflowAreas)
{
  nsReflowStatus reflowStatus = NS_FRAME_COMPLETE;

  const bool reflowAll = aReflowState.ShouldReflowAllKids();
  const bool isGrid = !!(aFlags & AbsPosReflowFlags::eIsGridContainerCB);
  nsIFrame* kidFrame;
  nsOverflowContinuationTracker tracker(aDelegatingFrame, true);
  for (kidFrame = mAbsoluteFrames.FirstChild(); kidFrame; kidFrame = kidFrame->GetNextSibling()) {
    bool kidNeedsReflow = reflowAll || NS_SUBTREE_DIRTY(kidFrame) ||
      FrameDependsOnContainer(kidFrame,
                              !!(aFlags & AbsPosReflowFlags::eCBWidthChanged),
                              !!(aFlags & AbsPosReflowFlags::eCBHeightChanged));
    if (kidNeedsReflow && !aPresContext->HasPendingInterrupt()) {
      // Reflow the frame
      nsReflowStatus  kidStatus = NS_FRAME_COMPLETE;
      const nsRect& cb = isGrid ? nsGridContainerFrame::GridItemCB(kidFrame)
                                : aContainingBlock;
      ReflowAbsoluteFrame(aDelegatingFrame, aPresContext, aReflowState, cb,
                          aFlags, kidFrame, kidStatus, aOverflowAreas);
      nsIFrame* nextFrame = kidFrame->GetNextInFlow();
      if (!NS_FRAME_IS_FULLY_COMPLETE(kidStatus) &&
          aDelegatingFrame->IsFrameOfType(nsIFrame::eCanContainOverflowContainers)) {
        // Need a continuation
        if (!nextFrame) {
          nextFrame =
            aPresContext->PresShell()->FrameConstructor()->
              CreateContinuingFrame(aPresContext, kidFrame, aDelegatingFrame);
        }
        // Add it as an overflow container.
        //XXXfr This is a hack to fix some of our printing dataloss.
        // See bug 154892. Not sure how to do it "right" yet; probably want
        // to keep continuations within an nsAbsoluteContainingBlock eventually.
        tracker.Insert(nextFrame, kidStatus);
        NS_MergeReflowStatusInto(&reflowStatus, kidStatus);
      }
      else {
        // Delete any continuations
        if (nextFrame) {
          nsOverflowContinuationTracker::AutoFinish fini(&tracker, kidFrame);
          nextFrame->GetParent()->DeleteNextInFlowChild(nextFrame, true);
        }
      }
    }
    else {
      tracker.Skip(kidFrame, reflowStatus);
      if (aOverflowAreas) {
        aDelegatingFrame->ConsiderChildOverflow(*aOverflowAreas, kidFrame);
      }
    }

    // Make a CheckForInterrupt call, here, not just HasPendingInterrupt.  That
    // will make sure that we end up reflowing aDelegatingFrame in cases when
    // one of our kids interrupted.  Otherwise we'd set the dirty or
    // dirty-children bit on the kid in the condition below, and then when
    // reflow completes and we go to mark dirty bits on all ancestors of that
    // kid we'll immediately bail out, because the kid already has a dirty bit.
    // In particular, we won't set any dirty bits on aDelegatingFrame, so when
    // the following reflow happens we won't reflow the kid in question.  This
    // might be slightly suboptimal in cases where |kidFrame| itself did not
    // interrupt, since we'll trigger a reflow of it too when it's not strictly
    // needed.  But the logic to not do that is enough more complicated, and
    // the case enough of an edge case, that this is probably better.
    if (kidNeedsReflow && aPresContext->CheckForInterrupt(aDelegatingFrame)) {
      if (aDelegatingFrame->GetStateBits() & NS_FRAME_IS_DIRTY) {
        kidFrame->AddStateBits(NS_FRAME_IS_DIRTY);
      } else {
        kidFrame->AddStateBits(NS_FRAME_HAS_DIRTY_CHILDREN);
      }
    }
  }

  // Abspos frames can't cause their parent to be incomplete,
  // only overflow incomplete.
  if (NS_FRAME_IS_NOT_COMPLETE(reflowStatus))
    NS_FRAME_SET_OVERFLOW_INCOMPLETE(reflowStatus);

  NS_MergeReflowStatusInto(&aReflowStatus, reflowStatus);
}

bool
nsColumnSetFrame::ReflowChildren(nsHTMLReflowMetrics&     aDesiredSize,
                                 const nsHTMLReflowState& aReflowState,
                                 nsReflowStatus&          aStatus,
                                 const ReflowConfig&      aConfig,
                                 bool                     aUnboundedLastColumn,
                                 nsCollapsingMargin*      aBottomMarginCarriedOut,
                                 ColumnBalanceData&       aColData)
{
  aColData.Reset();
  bool allFit = true;
  bool RTL = GetStyleVisibility()->mDirection == NS_STYLE_DIRECTION_RTL;
  bool shrinkingHeightOnly = !NS_SUBTREE_DIRTY(this) &&
    mLastBalanceHeight > aConfig.mColMaxHeight;
  
#ifdef DEBUG_roc
  printf("*** Doing column reflow pass: mLastBalanceHeight=%d, mColMaxHeight=%d, RTL=%d\n, mBalanceColCount=%d, mColWidth=%d, mColGap=%d\n",
         mLastBalanceHeight, aConfig.mColMaxHeight, RTL, aConfig.mBalanceColCount,
         aConfig.mColWidth, aConfig.mColGap);
#endif

  DrainOverflowColumns();
  
  if (mLastBalanceHeight != aConfig.mColMaxHeight) {
    mLastBalanceHeight = aConfig.mColMaxHeight;
    // XXX Seems like this could fire if incremental reflow pushed the column set
    // down so we reflow incrementally with a different available height.
    // We need a way to do an incremental reflow and be sure availableHeight
    // changes are taken account of! Right now I think block frames with absolute
    // children might exit early.
    //NS_ASSERTION(aKidReason != eReflowReason_Incremental,
    //             "incremental reflow should not have changed the balance height");
  }

  // get our border and padding
  const nsMargin &borderPadding = aReflowState.mComputedBorderPadding;
  
  nsRect contentRect(0, 0, 0, 0);
  nsOverflowAreas overflowRects;

  nsIFrame* child = mFrames.FirstChild();
  nsPoint childOrigin = nsPoint(borderPadding.left, borderPadding.top);
  // For RTL, figure out where the last column's left edge should be. Since the
  // columns might not fill the frame exactly, we need to account for the
  // slop. Otherwise we'll waste time moving the columns by some tiny
  // amount unnecessarily.
  nscoord targetX = borderPadding.left;
  if (RTL) {
    nscoord availWidth = aReflowState.availableWidth;
    if (aReflowState.ComputedWidth() != NS_INTRINSICSIZE) {
      availWidth = aReflowState.ComputedWidth();
    }
    if (availWidth != NS_INTRINSICSIZE) {
      childOrigin.x += availWidth - aConfig.mColWidth;
      targetX += aConfig.mExpectedWidthLeftOver;
#ifdef DEBUG_roc
      printf("*** childOrigin.x = %d\n", childOrigin.x);
#endif
    }
  }
  int columnCount = 0;
  int contentBottom = 0;
  bool reflowNext = false;

  while (child) {
    // Try to skip reflowing the child. We can't skip if the child is dirty. We also can't
    // skip if the next column is dirty, because the next column's first line(s)
    // might be pullable back to this column. We can't skip if it's the last child
    // because we need to obtain the bottom margin. We can't skip
    // if this is the last column and we're supposed to assign unbounded
    // height to it, because that could change the available height from
    // the last time we reflowed it and we should try to pull all the
    // content from its next sibling. (Note that it might be the last
    // column, but not be the last child because the desired number of columns
    // has changed.)
    bool skipIncremental = !aReflowState.ShouldReflowAllKids()
      && !NS_SUBTREE_DIRTY(child)
      && child->GetNextSibling()
      && !(aUnboundedLastColumn && columnCount == aConfig.mBalanceColCount - 1)
      && !NS_SUBTREE_DIRTY(child->GetNextSibling());
    // If we need to pull up content from the prev-in-flow then this is not just
    // a height shrink. The prev in flow will have set the dirty bit.
    // Check the overflow rect YMost instead of just the child's content height. The child
    // may have overflowing content that cares about the available height boundary.
    // (It may also have overflowing content that doesn't care about the available height
    // boundary, but if so, too bad, this optimization is defeated.)
    // We want scrollable overflow here since this is a calculation that
    // affects layout.
    bool skipResizeHeightShrink = shrinkingHeightOnly
      && child->GetScrollableOverflowRect().YMost() <= aConfig.mColMaxHeight;

    nscoord childContentBottom = 0;
    if (!reflowNext && (skipIncremental || skipResizeHeightShrink)) {
      // This child does not need to be reflowed, but we may need to move it
      MoveChildTo(this, child, childOrigin);
      
      // If this is the last frame then make sure we get the right status
      nsIFrame* kidNext = child->GetNextSibling();
      if (kidNext) {
        aStatus = (kidNext->GetStateBits() & NS_FRAME_IS_OVERFLOW_CONTAINER)
//.........这里部分代码省略.........

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

  NS_PRECONDITION(aReflowState.ComputedISize() != NS_INTRINSICSIZE,
                  "Should have a precomputed inline-size!");

  // Initialize OUT parameter
  aStatus = NS_FRAME_COMPLETE;

  nsOverflowAreas ocBounds;
  nsReflowStatus ocStatus = NS_FRAME_COMPLETE;
  if (GetPrevInFlow()) {
    ReflowOverflowContainerChildren(aPresContext, aReflowState, ocBounds, 0,
                                    ocStatus);
  }

  //------------ Handle Incremental Reflow -----------------
  bool reflowInner;
  bool reflowLegend;
  nsIFrame* legend = GetLegend();
  nsIFrame* inner = GetInner();
  if (aReflowState.ShouldReflowAllKids()) {
    reflowInner = inner != nullptr;
    reflowLegend = legend != nullptr;
  } else {
    reflowInner = inner && NS_SUBTREE_DIRTY(inner);
    reflowLegend = legend && NS_SUBTREE_DIRTY(legend);
  }

  // We don't allow fieldsets to break vertically. If we did, we'd
  // need logic here to push and pull overflow frames.
  // Since we're not applying our padding in this frame, we need to add it here
  // to compute the available width for our children.
  WritingMode wm = GetWritingMode();
  WritingMode innerWM = inner ? inner->GetWritingMode() : wm;
  WritingMode legendWM = legend ? legend->GetWritingMode() : wm;
  LogicalSize innerAvailSize = aReflowState.ComputedSizeWithPadding(innerWM);
  LogicalSize legendAvailSize = aReflowState.ComputedSizeWithPadding(legendWM);
  innerAvailSize.BSize(innerWM) = legendAvailSize.BSize(legendWM) =
    NS_UNCONSTRAINEDSIZE;
  NS_ASSERTION(!inner ||
      nsLayoutUtils::IntrinsicForContainer(aReflowState.rendContext,
                                           inner,
                                           nsLayoutUtils::MIN_ISIZE) <=
               innerAvailSize.ISize(innerWM),
               "Bogus availSize.ISize; should be bigger");
  NS_ASSERTION(!legend ||
      nsLayoutUtils::IntrinsicForContainer(aReflowState.rendContext,
                                           legend,
                                           nsLayoutUtils::MIN_ISIZE) <=
               legendAvailSize.ISize(legendWM),
               "Bogus availSize.ISize; should be bigger");

  // get our border and padding
  LogicalMargin border = aReflowState.ComputedLogicalBorderPadding() -
                         aReflowState.ComputedLogicalPadding();

  // Figure out how big the legend is if there is one.
  // get the legend's margin
  LogicalMargin legendMargin(wm);
  // reflow the legend only if needed
  Maybe<nsHTMLReflowState> legendReflowState;
  if (legend) {
    legendReflowState.emplace(aPresContext, aReflowState, legend,
                                legendAvailSize);
  }
  if (reflowLegend) {
    nsHTMLReflowMetrics legendDesiredSize(aReflowState);

    // We'll move the legend to its proper place later, so the position
    // and containerSize passed here are unimportant.
    const nsSize dummyContainerSize;
    ReflowChild(legend, aPresContext, legendDesiredSize, *legendReflowState,
                wm, LogicalPoint(wm), dummyContainerSize,
                NS_FRAME_NO_MOVE_FRAME, aStatus);
#ifdef NOISY_REFLOW
    printf("  returned (%d, %d)\n",
           legendDesiredSize.Width(), legendDesiredSize.Height());
#endif
    // figure out the legend's rectangle
    legendMargin = legend->GetLogicalUsedMargin(wm);
    mLegendRect =
      LogicalRect(wm, 0, 0,
                  legendDesiredSize.ISize(wm) + legendMargin.IStartEnd(wm),
                  legendDesiredSize.BSize(wm) + legendMargin.BStartEnd(wm));
    nscoord oldSpace = mLegendSpace;
    mLegendSpace = 0;
    if (mLegendRect.BSize(wm) > border.BStart(wm)) {
      // center the border on the legend
      mLegendSpace = mLegendRect.BSize(wm) - border.BStart(wm);
    } else {
      mLegendRect.BStart(wm) =
        (border.BStart(wm) - mLegendRect.BSize(wm)) / 2;
//.........这里部分代码省略.........

void
ViewportFrame::Reflow(nsPresContext*           aPresContext,
                      nsHTMLReflowMetrics&     aDesiredSize,
                      const nsHTMLReflowState& aReflowState,
                      nsReflowStatus&          aStatus)
{
  MarkInReflow();
  DO_GLOBAL_REFLOW_COUNT("ViewportFrame");
  DISPLAY_REFLOW(aPresContext, this, aReflowState, aDesiredSize, aStatus);
  NS_FRAME_TRACE_REFLOW_IN("ViewportFrame::Reflow");

  // Initialize OUT parameters
  aStatus = NS_FRAME_COMPLETE;

  // Because |Reflow| sets ComputedBSize() on the child to our
  // ComputedBSize().
  AddStateBits(NS_FRAME_CONTAINS_RELATIVE_BSIZE);

  // Set our size up front, since some parts of reflow depend on it
  // being already set.  Note that the computed height may be
  // unconstrained; that's ok.  Consumers should watch out for that.
  SetSize(nsSize(aReflowState.ComputedWidth(), aReflowState.ComputedHeight()));

  // Reflow the main content first so that the placeholders of the
  // fixed-position frames will be in the right places on an initial
  // reflow.
  nscoord kidBSize = 0;
  WritingMode wm = aReflowState.GetWritingMode();

  if (mFrames.NotEmpty()) {
    // Deal with a non-incremental reflow or an incremental reflow
    // targeted at our one-and-only principal child frame.
    if (aReflowState.ShouldReflowAllKids() ||
        aReflowState.IsVResize() ||
        NS_SUBTREE_DIRTY(mFrames.FirstChild())) {
      // Reflow our one-and-only principal child frame
      nsIFrame*           kidFrame = mFrames.FirstChild();
      nsHTMLReflowMetrics kidDesiredSize(aReflowState);
      WritingMode         wm = kidFrame->GetWritingMode();
      LogicalSize         availableSpace = aReflowState.AvailableSize(wm);
      nsHTMLReflowState   kidReflowState(aPresContext, aReflowState,
                                         kidFrame, availableSpace);

      // Reflow the frame
      kidReflowState.SetComputedBSize(aReflowState.ComputedBSize());
      ReflowChild(kidFrame, aPresContext, kidDesiredSize, kidReflowState,
                  0, 0, 0, aStatus);
      kidBSize = kidDesiredSize.BSize(wm);

      FinishReflowChild(kidFrame, aPresContext, kidDesiredSize, nullptr, 0, 0, 0);
    } else {
      kidBSize = LogicalSize(wm, mFrames.FirstChild()->GetSize()).BSize(wm);
    }
  }

  NS_ASSERTION(aReflowState.AvailableISize() != NS_UNCONSTRAINEDSIZE,
               "shouldn't happen anymore");

  // Return the max size as our desired size
  LogicalSize maxSize(wm, aReflowState.AvailableISize(),
                      // Being flowed initially at an unconstrained block size
                      // means we should return our child's intrinsic size.
                      aReflowState.ComputedBSize() != NS_UNCONSTRAINEDSIZE
                        ? aReflowState.ComputedBSize()
                        : kidBSize);
  aDesiredSize.SetSize(wm, maxSize);
  aDesiredSize.SetOverflowAreasToDesiredBounds();

  if (HasAbsolutelyPositionedChildren()) {
    // Make a copy of the reflow state and change the computed width and height
    // to reflect the available space for the fixed items
    nsHTMLReflowState reflowState(aReflowState);

    if (reflowState.AvailableBSize() == NS_UNCONSTRAINEDSIZE) {
      // We have an intrinsic-height document with abs-pos/fixed-pos children.
      // Set the available height and mComputedHeight to our chosen height.
      reflowState.AvailableBSize() = maxSize.BSize(wm);
      // Not having border/padding simplifies things
      NS_ASSERTION(reflowState.ComputedPhysicalBorderPadding() == nsMargin(0,0,0,0),
                   "Viewports can't have border/padding");
      reflowState.SetComputedBSize(maxSize.BSize(wm));
    }

    nsRect rect = AdjustReflowStateAsContainingBlock(&reflowState);
    nsOverflowAreas* overflowAreas = &aDesiredSize.mOverflowAreas;
    nsIScrollableFrame* rootScrollFrame =
                    aPresContext->PresShell()->GetRootScrollFrameAsScrollable();
    if (rootScrollFrame && !rootScrollFrame->IsIgnoringViewportClipping()) {
      overflowAreas = nullptr;
    }
    AbsPosReflowFlags flags =
      AbsPosReflowFlags::eCBWidthAndHeightChanged; // XXX could be optimized
    GetAbsoluteContainingBlock()->Reflow(this, aPresContext, reflowState, aStatus,
                                         rect, flags, overflowAreas);
  }

  if (mFrames.NotEmpty()) {
    ConsiderChildOverflow(aDesiredSize.mOverflowAreas, mFrames.FirstChild());
  }

//.........这里部分代码省略.........

NS_IMETHODIMP
ViewportFrame::Reflow(nsPresContext*           aPresContext,
                      nsHTMLReflowMetrics&     aDesiredSize,
                      const nsHTMLReflowState& aReflowState,
                      nsReflowStatus&          aStatus)
{
  DO_GLOBAL_REFLOW_COUNT("ViewportFrame");
  DISPLAY_REFLOW(aPresContext, this, aReflowState, aDesiredSize, aStatus);
  NS_FRAME_TRACE_REFLOW_IN("ViewportFrame::Reflow");

  // Initialize OUT parameters
  aStatus = NS_FRAME_COMPLETE;

  // Because |Reflow| sets mComputedHeight on the child to
  // availableHeight.
  AddStateBits(NS_FRAME_CONTAINS_RELATIVE_HEIGHT);

  // Set our size up front, since some parts of reflow depend on it
  // being already set.  Note that the computed height may be
  // unconstrained; that's ok.  Consumers should watch out for that.
  SetSize(nsSize(aReflowState.ComputedWidth(), aReflowState.ComputedHeight()));
 
  // Reflow the main content first so that the placeholders of the
  // fixed-position frames will be in the right places on an initial
  // reflow.
  nscoord kidHeight = 0;

  nsresult rv = NS_OK;
  
  if (mFrames.NotEmpty()) {
    // Deal with a non-incremental reflow or an incremental reflow
    // targeted at our one-and-only principal child frame.
    if (aReflowState.ShouldReflowAllKids() ||
        aReflowState.mFlags.mVResize ||
        NS_SUBTREE_DIRTY(mFrames.FirstChild())) {
      // Reflow our one-and-only principal child frame
      nsIFrame*           kidFrame = mFrames.FirstChild();
      nsHTMLReflowMetrics kidDesiredSize;
      nsSize              availableSpace(aReflowState.availableWidth,
                                         aReflowState.availableHeight);
      nsHTMLReflowState   kidReflowState(aPresContext, aReflowState,
                                         kidFrame, availableSpace);

      // Reflow the frame
      kidReflowState.SetComputedHeight(aReflowState.ComputedHeight());
      rv = ReflowChild(kidFrame, aPresContext, kidDesiredSize, kidReflowState,
                       0, 0, 0, aStatus);
      kidHeight = kidDesiredSize.height;

      FinishReflowChild(kidFrame, aPresContext, nsnull, kidDesiredSize, 0, 0, 0);
    } else {
      kidHeight = mFrames.FirstChild()->GetSize().height;
    }
  }

  NS_ASSERTION(aReflowState.availableWidth != NS_UNCONSTRAINEDSIZE,
               "shouldn't happen anymore");

  // Return the max size as our desired size
  aDesiredSize.width = aReflowState.availableWidth;
  // Being flowed initially at an unconstrained height means we should
  // return our child's intrinsic size.
  aDesiredSize.height = aReflowState.ComputedHeight() != NS_UNCONSTRAINEDSIZE
                          ? aReflowState.ComputedHeight()
                          : kidHeight;

  // Make a copy of the reflow state and change the computed width and height
  // to reflect the available space for the fixed items
  nsHTMLReflowState reflowState(aReflowState);
  nsPoint offset = AdjustReflowStateForScrollbars(&reflowState);
  
#ifdef DEBUG
  NS_ASSERTION(mFixedContainer.GetChildList().IsEmpty() ||
               (offset.x == 0 && offset.y == 0),
               "We don't handle correct positioning of fixed frames with "
               "scrollbars in odd positions");
#endif

  // Just reflow all the fixed-pos frames.
  rv = mFixedContainer.Reflow(this, aPresContext, reflowState, aStatus,
                              reflowState.ComputedWidth(),
                              reflowState.ComputedHeight(),
                              PR_FALSE, PR_TRUE, PR_TRUE); // XXX could be optimized

  // If we were dirty then do a repaint
  if (GetStateBits() & NS_FRAME_IS_DIRTY) {
    nsRect damageRect(0, 0, aDesiredSize.width, aDesiredSize.height);
    Invalidate(damageRect);
  }

  // XXX Should we do something to clip our children to this?
  aDesiredSize.mOverflowArea =
    nsRect(nsPoint(0, 0), nsSize(aDesiredSize.width, aDesiredSize.height));

  NS_FRAME_TRACE_REFLOW_OUT("ViewportFrame::Reflow", aStatus);
  NS_FRAME_SET_TRUNCATION(aStatus, aReflowState, aDesiredSize);
  return rv; 
}

bool
nsColumnSetFrame::ReflowChildren(nsHTMLReflowMetrics&     aDesiredSize,
                                 const nsHTMLReflowState& aReflowState,
                                 nsReflowStatus&          aStatus,
                                 const ReflowConfig&      aConfig,
                                 bool                     aUnboundedLastColumn,
                                 nsCollapsingMargin*      aCarriedOutBEndMargin,
                                 ColumnBalanceData&       aColData)
{
    aColData.Reset();
    bool allFit = true;
    WritingMode wm = GetWritingMode();
    bool isVertical = wm.IsVertical();
    bool isRTL = !wm.IsBidiLTR();
    bool shrinkingBSizeOnly = !NS_SUBTREE_DIRTY(this) &&
                              mLastBalanceBSize > aConfig.mColMaxBSize;

#ifdef DEBUG_roc
    printf("*** Doing column reflow pass: mLastBalanceBSize=%d, mColMaxBSize=%d, RTL=%d\n"
           "    mBalanceColCount=%d, mColISize=%d, mColGap=%d\n",
           mLastBalanceBSize, aConfig.mColMaxBSize, isRTL, aConfig.mBalanceColCount,
           aConfig.mColISize, aConfig.mColGap);
#endif

    DrainOverflowColumns();

    const bool colBSizeChanged = mLastBalanceBSize != aConfig.mColMaxBSize;

    if (colBSizeChanged) {
        mLastBalanceBSize = aConfig.mColMaxBSize;
        // XXX Seems like this could fire if incremental reflow pushed the column set
        // down so we reflow incrementally with a different available height.
        // We need a way to do an incremental reflow and be sure availableHeight
        // changes are taken account of! Right now I think block frames with absolute
        // children might exit early.
        //NS_ASSERTION(aKidReason != eReflowReason_Incremental,
        //             "incremental reflow should not have changed the balance height");
    }

    // get our border and padding
    LogicalMargin borderPadding = aReflowState.ComputedLogicalBorderPadding();
    borderPadding.ApplySkipSides(GetLogicalSkipSides(&aReflowState));

    nsRect contentRect(0, 0, 0, 0);
    nsOverflowAreas overflowRects;

    nsIFrame* child = mFrames.FirstChild();
    LogicalPoint childOrigin(wm, borderPadding.IStart(wm),
                             borderPadding.BStart(wm));
    // In vertical-rl mode, columns will not be correctly placed if the
    // reflowState's ComputedWidth() is UNCONSTRAINED (in which case we'll get
    // a containerSize.width of zero here). In that case, the column positions
    // will be adjusted later, after our correct contentSize is known.
    nsSize containerSize = aReflowState.ComputedSizeAsContainerIfConstrained();

    // For RTL, since the columns might not fill the frame exactly, we
    // need to account for the slop. Otherwise we'll waste time moving the
    // columns by some tiny amount

    // XXX when all of layout is converted to logical coordinates, we
    //     probably won't need to do this hack any more. For now, we
    //     confine it to the legacy horizontal-rl case
    if (!isVertical && isRTL) {
        nscoord availISize = aReflowState.AvailableISize();
        if (aReflowState.ComputedISize() != NS_INTRINSICSIZE) {
            availISize = aReflowState.ComputedISize();
        }
        if (availISize != NS_INTRINSICSIZE) {
            childOrigin.I(wm) = containerSize.width - borderPadding.Left(wm) -
                                availISize;
#ifdef DEBUG_roc
            printf("*** childOrigin.iCoord = %d\n", childOrigin.I(wm));
#endif
        }
    }

    int columnCount = 0;
    int contentBEnd = 0;
    bool reflowNext = false;

    while (child) {
        // Try to skip reflowing the child. We can't skip if the child is dirty. We also can't
        // skip if the next column is dirty, because the next column's first line(s)
        // might be pullable back to this column. We can't skip if it's the last child
        // because we need to obtain the bottom margin. We can't skip
        // if this is the last column and we're supposed to assign unbounded
        // height to it, because that could change the available height from
        // the last time we reflowed it and we should try to pull all the
        // content from its next sibling. (Note that it might be the last
        // column, but not be the last child because the desired number of columns
        // has changed.)
        bool skipIncremental = !aReflowState.ShouldReflowAllKids()
                               && !NS_SUBTREE_DIRTY(child)
                               && child->GetNextSibling()
                               && !(aUnboundedLastColumn && columnCount == aConfig.mBalanceColCount - 1)
                               && !NS_SUBTREE_DIRTY(child->GetNextSibling());
        // If we need to pull up content from the prev-in-flow then this is not just
        // a height shrink. The prev in flow will have set the dirty bit.
        // Check the overflow rect YMost instead of just the child's content height. The child
        // may have overflowing content that cares about the available height boundary.
//.........这里部分代码省略.........