gecko-dev/layout/generic/nsAbsoluteContainingBlock.cpp

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is mozilla.org code.
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 1998
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either of the GNU General Public License Version 2 or later (the "GPL"),
 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

/*
 * code for managing absolutely positioned children of a rendering
 * object that is a containing block for them
 */

#include "nsCOMPtr.h"
#include "nsAbsoluteContainingBlock.h"
#include "nsContainerFrame.h"
#include "nsReflowPath.h"
#include "nsIViewManager.h"
#include "nsLayoutAtoms.h"
#include "nsIPresShell.h"
#include "nsHTMLParts.h"
#include "nsPresContext.h"

#ifdef DEBUG
#include "nsBlockFrame.h"
#endif


nsresult
nsAbsoluteContainingBlock::FirstChild(const nsIFrame* aDelegatingFrame,
                                      nsIAtom*        aListName,
                                      nsIFrame**      aFirstChild) const
{
  NS_PRECONDITION(GetChildListName() == aListName, "unexpected child list name");
  *aFirstChild = mAbsoluteFrames.FirstChild();
  return NS_OK;
}

nsresult
nsAbsoluteContainingBlock::SetInitialChildList(nsIFrame*       aDelegatingFrame,
                                               nsIAtom*        aListName,
                                               nsIFrame*       aChildList)
{
  NS_PRECONDITION(GetChildListName() == aListName, "unexpected child list name");
#ifdef NS_DEBUG
  nsFrame::VerifyDirtyBitSet(aChildList);
#endif
  mAbsoluteFrames.SetFrames(aChildList);
  return NS_OK;
}

nsresult
nsAbsoluteContainingBlock::AppendFrames(nsIFrame*      aDelegatingFrame,
                                        nsIAtom*       aListName,
                                        nsIFrame*      aFrameList)
{
  // Append the frames to our list of absolutely positioned frames
#ifdef NS_DEBUG
  nsFrame::VerifyDirtyBitSet(aFrameList);
#endif
  mAbsoluteFrames.AppendFrames(nsnull, aFrameList);

  // Generate a reflow command to reflow the dirty frames
  return aDelegatingFrame->GetPresContext()->PresShell()->
          AppendReflowCommand(aDelegatingFrame, eReflowType_ReflowDirty,
                              GetChildListName());
}

nsresult
nsAbsoluteContainingBlock::InsertFrames(nsIFrame*      aDelegatingFrame,
                                        nsIAtom*       aListName,
                                        nsIFrame*      aPrevFrame,
                                        nsIFrame*      aFrameList)
{
  // Insert the new frames
#ifdef NS_DEBUG
  nsFrame::VerifyDirtyBitSet(aFrameList);
#endif
  mAbsoluteFrames.InsertFrames(nsnull, aPrevFrame, aFrameList);

  // Generate a reflow command to reflow the dirty frames
  return aDelegatingFrame->GetPresContext()->PresShell()->
          AppendReflowCommand(aDelegatingFrame, eReflowType_ReflowDirty,
                              GetChildListName());
}

nsresult
nsAbsoluteContainingBlock::RemoveFrame(nsIFrame*       aDelegatingFrame,
                                       nsIAtom*        aListName,
                                       nsIFrame*       aOldFrame)
{
  PRBool result = mAbsoluteFrames.DestroyFrame(aOldFrame);
  NS_ASSERTION(result, "didn't find frame to delete");
  // Because positioned frames aren't part of a flow, there's no additional
  // work to do, e.g. reflowing sibling frames. And because positioned frames
  // have a view, we don't need to repaint
  return result ? NS_OK : NS_ERROR_FAILURE;
}

static void
AddFrameToChildBounds(nsIFrame* aKidFrame, nsRect* aChildBounds)
{
  NS_PRECONDITION(aKidFrame, "Must have kid frame");
  
  if (!aChildBounds) {
    return;
  }

  // Add in the child's bounds
  nsRect kidBounds = aKidFrame->GetRect();
  nsRect* kidOverflow = aKidFrame->GetOverflowAreaProperty();
  if (kidOverflow) {
    // Put it in the parent's coordinate system
    kidBounds = *kidOverflow + kidBounds.TopLeft();
  }
  aChildBounds->UnionRect(*aChildBounds, kidBounds);
}

nsresult
nsAbsoluteContainingBlock::Reflow(nsIFrame*                aDelegatingFrame,
                                  nsPresContext*          aPresContext,
                                  const nsHTMLReflowState& aReflowState,
                                  nscoord                  aContainingBlockWidth,
                                  nscoord                  aContainingBlockHeight,
                                  nsRect*                  aChildBounds,
                                  PRBool                   aForceReflow,
                                  PRBool                   aCBWidthChanged,
                                  PRBool                   aCBHeightChanged)
{
  // Initialize OUT parameter
  if (aChildBounds)
    aChildBounds->SetRect(0, 0, 0, 0);

  // Make a copy of the reflow state.  If the reason is
  // eReflowReason_Incremental (which should mean either that the target
  // is the frame for which this is the absolute container or that the
  // container changed size due to incremental reflow of its children),
  // then change it to eReflowReason_Resize.
  // XXXldb If the target is this frame, shouldn't we be setting it
  // appropriately (which might mean to StyleChanged)?
  nsHTMLReflowState reflowState(aReflowState);
  if (eReflowReason_Incremental == reflowState.reason) {
    reflowState.reason = eReflowReason_Resize;
  }

  nsIFrame* kidFrame;
  for (kidFrame = mAbsoluteFrames.FirstChild(); kidFrame; kidFrame = kidFrame->GetNextSibling()) {
    if (!aForceReflow &&
        !FrameDependsOnContainer(kidFrame, aCBWidthChanged, aCBHeightChanged)) {
      // Skip this frame, but add it in to the child bounds as needed
      AddFrameToChildBounds(kidFrame, aChildBounds);
      continue;
    }
    nsReflowReason  reason = reflowState.reason;

    nsFrameState kidState = kidFrame->GetStateBits();
    if (NS_FRAME_FIRST_REFLOW & kidState) {
      // The frame has never had a reflow, so change the reason to eReflowReason_Initial
      reason = eReflowReason_Initial;

    } else if (NS_FRAME_IS_DIRTY & kidState) {
      // The frame is dirty so give it the correct reflow reason
      reason = eReflowReason_Dirty;
    }

    // Reflow the frame
    nsReflowStatus  kidStatus;
    ReflowAbsoluteFrame(aDelegatingFrame, aPresContext, reflowState, aContainingBlockWidth,
                        aContainingBlockHeight, kidFrame, reason, kidStatus);

    AddFrameToChildBounds(kidFrame, aChildBounds);
  }
  return NS_OK;
}

void
nsAbsoluteContainingBlock::CalculateChildBounds(nsPresContext* aPresContext,
                                                nsRect&         aChildBounds)
{
  // Initialize the OUT parameters
  aChildBounds.SetRect(0, 0, 0, 0);

  for (nsIFrame* f = mAbsoluteFrames.FirstChild(); f; f = f->GetNextSibling()) {
    AddFrameToChildBounds(f, &aChildBounds);
  }
}

PRBool
nsAbsoluteContainingBlock::ReflowingAbsolutesOnly(nsIFrame* aDelegatingFrame,
                                                  const nsHTMLReflowState& aReflowState)
{
  // See if the reflow command is targeted at us.
  nsReflowPath *path = aReflowState.path;
  nsHTMLReflowCommand *command = path->mReflowCommand;

  if (command) {
    // It's targeted at us. See if it's for the positioned child frames
    if (GetChildListName() != command->GetChildListName()) {
      // A reflow command is targeted directly at this block.
      // The block will have to do a proper reflow.
      return PR_FALSE;
    }
  }

  nsReflowPath::iterator iter = path->FirstChild();
  nsReflowPath::iterator end = path->EndChildren();

  if (iter != end && mAbsoluteFrames.NotEmpty()) {
    for ( ; iter != end; ++iter) {
      // See if it's one of our absolutely positioned child frames
      if (!mAbsoluteFrames.ContainsFrame(*iter)) {
        // At least one of the frames along the reflow path wasn't
        // absolutely positioned, so we'll need to deal with it in
        // normal block reflow.
        return PR_FALSE;
      }
    }
  }

  return PR_TRUE;
}

static PRBool IsFixedPaddingSize(nsStyleUnit aUnit) {
  return aUnit == eStyleUnit_Coord || aUnit == eStyleUnit_Null;
}
static PRBool IsFixedMarginSize(nsStyleUnit aUnit) {
  return aUnit == eStyleUnit_Coord || aUnit == eStyleUnit_Null;
}
static PRBool IsFixedMaxSize(nsStyleUnit aUnit) {
  return aUnit == eStyleUnit_Null || aUnit == eStyleUnit_Coord;
}

PRBool
nsAbsoluteContainingBlock::FrameDependsOnContainer(nsIFrame* f,
                                                   PRBool aCBWidthChanged,
                                                   PRBool aCBHeightChanged)
{
  const nsStylePosition* pos = f->GetStylePosition();
  // See if f's position might have changed because it depends on a
  // placeholder's position
  // This can happen in the following cases:
  // 1) Vertical positioning.  "top" must be auto and "bottom" must be auto
  //    (otherwise the vertical position is completely determined by
  //    whichever of them is not auto and the height).
  // 2) Horizontal positioning.  "left" must be auto and "right" must be auto
  //    (otherwise the horizontal position is completely determined by
  //    whichever of them is not auto and the width).
  // See nsHTMLReflowState::InitAbsoluteConstraints -- these are the
  // only cases when we call CalculateHypotheticalBox().
  if ((pos->mOffset.GetTopUnit() == eStyleUnit_Auto &&
       pos->mOffset.GetBottomUnit() == eStyleUnit_Auto) ||
      (pos->mOffset.GetLeftUnit() == eStyleUnit_Auto &&
       pos->mOffset.GetRightUnit() == eStyleUnit_Auto)) {
    return PR_TRUE;
  }
  if (!aCBWidthChanged && !aCBHeightChanged) {
    // skip getting style data
    return PR_FALSE;
  }
  const nsStylePadding* padding = f->GetStylePadding();
  const nsStyleMargin* margin = f->GetStyleMargin();
  if (aCBWidthChanged) {
    // See if f's width might have changed.
    // If border-left, border-right, padding-left, padding-right,
    // width, min-width, and max-width are all lengths, 'none', or enumerated,
    // then our frame width does not depend on the parent width.
    // Note that borders never depend on the parent width
    if (pos->mWidth.GetUnit() != eStyleUnit_Coord ||
        pos->mMinWidth.GetUnit() != eStyleUnit_Coord ||
        !IsFixedMaxSize(pos->mMaxWidth.GetUnit()) ||
        !IsFixedPaddingSize(padding->mPadding.GetLeftUnit()) ||
        !IsFixedPaddingSize(padding->mPadding.GetRightUnit())) {
      return PR_TRUE;
    }

    // See if f's position might have changed. If we're RTL then the
    // rules are slightly different. We'll assume percentage or auto
    // margins will always induce a dependency on the size
    if (!IsFixedMarginSize(margin->mMargin.GetLeftUnit()) ||
        !IsFixedMarginSize(margin->mMargin.GetRightUnit())) {
      return PR_TRUE;
    }
    if (f->GetStyleVisibility()->mDirection == NS_STYLE_DIRECTION_RTL) {
      // Note that even if 'left' is a length, our position can
      // still depend on the containing block width, because if
      // 'right' is also a length we will discard 'left' and be
      // positioned relative to the containing block right edge.
      // 'left' length and 'right' auto is the only combination
      // we can be sure of.
      if (pos->mOffset.GetLeftUnit() != eStyleUnit_Coord ||
          pos->mOffset.GetRightUnit() != eStyleUnit_Auto) {
        return PR_TRUE;
      }
    } else {
      if (pos->mOffset.GetLeftUnit() != eStyleUnit_Coord) {
        return PR_TRUE;
      }
    }
  }
  if (aCBHeightChanged) {
    // See if f's height might have changed.
    // If border-top, border-bottom, padding-top, padding-bottom,
    // min-height, and max-height are all lengths or 'none',
    // and height is a length or height and bottom are auto and top is not auto,
    // then our frame height does not depend on the parent height.
    // Note that borders never depend on the parent height
    if (!(pos->mHeight.GetUnit() == eStyleUnit_Coord ||
          (pos->mHeight.GetUnit() == eStyleUnit_Auto &&
           pos->mOffset.GetBottomUnit() == eStyleUnit_Auto &&
           pos->mOffset.GetTopUnit() != eStyleUnit_Auto)) ||
        pos->mMinHeight.GetUnit() != eStyleUnit_Coord ||
        !IsFixedMaxSize(pos->mMaxHeight.GetUnit()) ||
        !IsFixedPaddingSize(padding->mPadding.GetTopUnit()) ||
        !IsFixedPaddingSize(padding->mPadding.GetBottomUnit())) { 
      return PR_TRUE;
    }
      
    // See if f's position might have changed.
    if (!IsFixedMarginSize(margin->mMargin.GetTopUnit()) ||
        !IsFixedMarginSize(margin->mMargin.GetBottomUnit())) {
      return PR_TRUE;
    }
    if (pos->mOffset.GetTopUnit() != eStyleUnit_Coord) {
      return PR_TRUE;
    }
  }
  return PR_FALSE;
}

void
nsAbsoluteContainingBlock::IncrementalReflow(nsIFrame*                aDelegatingFrame,
                                             nsPresContext*           aPresContext,
                                             const nsHTMLReflowState& aReflowState,
                                             nscoord                  aContainingBlockWidth,
                                             nscoord                  aContainingBlockHeight)
{
  // See if the reflow command is targeted at us.
  nsReflowPath *path = aReflowState.path;
  nsHTMLReflowCommand *command = path->mReflowCommand;

  if (command) {
    // It's targeted at us. See if it's for the positioned child frames
    if (GetChildListName() == command->GetChildListName()) {
      // The only type of reflow command we expect is that we have dirty
      // child frames to reflow
      NS_ASSERTION(command->Type() == eReflowType_ReflowDirty,
                   "unexpected reflow type");

      // Walk the positioned frames and reflow the dirty frames
      for (nsIFrame* f = mAbsoluteFrames.FirstChild(); f; f = f->GetNextSibling()) {
        nsFrameState  frameState = f->GetStateBits();

        if (frameState & NS_FRAME_IS_DIRTY) {
          nsReflowStatus  status;
          nsReflowReason  reason;

          reason = (frameState & NS_FRAME_FIRST_REFLOW)
            ? eReflowReason_Initial
            : eReflowReason_Dirty;

          ReflowAbsoluteFrame(aDelegatingFrame, aPresContext, aReflowState,
                              aContainingBlockWidth, aContainingBlockHeight, f,
                              reason, status);
        }
      }
    }
  }

  nsReflowPath::iterator iter = path->FirstChild();
  nsReflowPath::iterator end = path->EndChildren();

  if (iter != end && mAbsoluteFrames.NotEmpty()) {
    for ( ; iter != end; ++iter) {
      // See if it's one of our absolutely positioned child frames
      if (mAbsoluteFrames.ContainsFrame(*iter)) {
        // Remove the next frame from the reflow path
        nsReflowStatus kidStatus;
        ReflowAbsoluteFrame(aDelegatingFrame, aPresContext, aReflowState,
                            aContainingBlockWidth, aContainingBlockHeight, *iter,
                            aReflowState.reason, kidStatus);

        aReflowState.path->Remove(iter);
      }
    }
  }
}

void
nsAbsoluteContainingBlock::DestroyFrames(nsIFrame* aDelegatingFrame)
{
  mAbsoluteFrames.DestroyFrames();
}

// XXX Optimize the case where it's a resize reflow and the absolutely
// positioned child has the exact same size and position and skip the
// reflow...

// When bug 154892 is checked in, make sure that when 
// GetChildListName() == nsLayoutAtoms::fixedList, the height is unconstrained.
// since we don't allow replicated frames to split.

nsresult
nsAbsoluteContainingBlock::ReflowAbsoluteFrame(nsIFrame*                aDelegatingFrame,
                                               nsPresContext*          aPresContext,
                                               const nsHTMLReflowState& aReflowState,
                                               nscoord                  aContainingBlockWidth,
                                               nscoord                  aContainingBlockHeight,
                                               nsIFrame*                aKidFrame,
                                               nsReflowReason           aReason,
                                               nsReflowStatus&          aStatus)
{
#ifdef DEBUG
  if (nsBlockFrame::gNoisyReflow) {
    nsFrame::IndentBy(stdout,nsBlockFrame::gNoiseIndent);
    printf("abs pos ");
    if (nsnull != aKidFrame) {
      nsIFrameDebug*  frameDebug;
      if (NS_SUCCEEDED(CallQueryInterface(aKidFrame, &frameDebug))) {
        nsAutoString name;
        frameDebug->GetFrameName(name);
        printf("%s ", NS_LossyConvertUTF16toASCII(name).get());
      }
    }
    printf("r=%d",aReflowState.reason);

    if (aReflowState.reason == eReflowReason_Incremental) {
      nsHTMLReflowCommand *command = aReflowState.path->mReflowCommand;

      if (command) {
        // We're the target.
        printf("(%d)", command->Type());      
      }
    }
    char width[16];
    char height[16];
    PrettyUC(aReflowState.availableWidth, width);
    PrettyUC(aReflowState.availableHeight, height);
    printf(" a=%s,%s ", width, height);
    PrettyUC(aReflowState.mComputedWidth, width);
    PrettyUC(aReflowState.mComputedHeight, height);
    printf("c=%s,%s \n", width, height);
  }
  AutoNoisyIndenter indent(nsBlockFrame::gNoisy);
#endif // DEBUG

  nsresult  rv;
  // Get the border values
  const nsMargin& border = aReflowState.mStyleBorder->GetBorder();

  nscoord availWidth = aReflowState.mComputedWidth;
  enum { NOT_SHRINK_TO_FIT, SHRINK_TO_FIT_AVAILWIDTH, SHRINK_TO_FIT_MEW };
  PRUint32 situation = NOT_SHRINK_TO_FIT;
  while (1) {
    nsHTMLReflowMetrics kidDesiredSize(nsnull);
    if (situation == NOT_SHRINK_TO_FIT &&
        !(aKidFrame->GetStateBits() & NS_FRAME_REPLACED_ELEMENT)) {
      // CSS2.1 10.3.7 width:auto and at least one of left/right is auto...
      const nsStylePosition* stylePosition = aKidFrame->GetStylePosition();
      if (eStyleUnit_Auto == stylePosition->mWidth.GetUnit() &&
          (eStyleUnit_Auto == stylePosition->mOffset.GetLeftUnit() ||
           eStyleUnit_Auto == stylePosition->mOffset.GetRightUnit())) {
        situation = SHRINK_TO_FIT_AVAILWIDTH;
        if (aContainingBlockWidth != -1) {
          availWidth = aContainingBlockWidth;
        } else {
          availWidth = aReflowState.mComputedWidth;
        }
        kidDesiredSize.mComputeMEW = PR_TRUE;
      }
    }

    nsSize            availSize(availWidth, NS_UNCONSTRAINEDSIZE);
    nsHTMLReflowState kidReflowState(aPresContext, aReflowState, aKidFrame,
                                     availSize, aContainingBlockWidth,
                                     aContainingBlockHeight,
                                     aReason);

    if (situation == SHRINK_TO_FIT_MEW) {
      situation = NOT_SHRINK_TO_FIT; // This is the last reflow
      kidReflowState.mComputedWidth = PR_MIN(availWidth, kidReflowState.mComputedMaxWidth);
      if (kidReflowState.mComputedWidth < kidReflowState.mComputedMinWidth) {
        kidReflowState.mComputedWidth = kidReflowState.mComputedMinWidth;
      }
    } else if (situation == SHRINK_TO_FIT_AVAILWIDTH) {
      NS_ASSERTION(availWidth != NS_UNCONSTRAINEDSIZE,
                   "shrink-to-fit: expected a constrained available width");
      PRInt32 maxWidth = availWidth -
        (kidReflowState.mComputedMargin.left + kidReflowState.mComputedBorderPadding.left +
         kidReflowState.mComputedBorderPadding.right + kidReflowState.mComputedMargin.right);
      if (NS_AUTOOFFSET != kidReflowState.mComputedOffsets.right) {
        maxWidth -= kidReflowState.mComputedOffsets.right;
      }
      if (NS_AUTOOFFSET != kidReflowState.mComputedOffsets.left) {
        maxWidth -= kidReflowState.mComputedOffsets.left;
      }
      // The following also takes care of maxWidth<0
      if (kidReflowState.mComputedMaxWidth > maxWidth) {
        kidReflowState.mComputedMaxWidth = PR_MAX(maxWidth, kidReflowState.mComputedMinWidth);
      }
    }

    // Send the WillReflow() notification and position the frame
    aKidFrame->WillReflow(aPresContext);

    // XXXldb We can simplify this if we come up with a better way to
    // position views.
    nscoord x;
    if (NS_AUTOOFFSET == kidReflowState.mComputedOffsets.left) {
      // Just use the current x-offset
      x = aKidFrame->GetPosition().x;
    } else {
      x = border.left + kidReflowState.mComputedOffsets.left + kidReflowState.mComputedMargin.left;
    }
    aKidFrame->SetPosition(nsPoint(x, border.top +
                                      kidReflowState.mComputedOffsets.top +
                                      kidReflowState.mComputedMargin.top));

    // Position its view, but don't bother it doing it now if we haven't
    // yet determined the left offset
    if (NS_AUTOOFFSET != kidReflowState.mComputedOffsets.left) {
      nsContainerFrame::PositionFrameView(aKidFrame);
    }

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

    if (situation == SHRINK_TO_FIT_AVAILWIDTH) {
      // ...continued CSS2.1 10.3.7 width:auto and at least one of left/right is auto
      availWidth -= kidReflowState.mComputedMargin.left + kidReflowState.mComputedMargin.right;

      if (NS_AUTOOFFSET == kidReflowState.mComputedOffsets.right) {
        NS_ASSERTION(NS_AUTOOFFSET != kidReflowState.mComputedOffsets.left,
                     "Can't solve for both left and right");
        availWidth -= kidReflowState.mComputedOffsets.left;
      } else {
        NS_ASSERTION(NS_AUTOOFFSET == kidReflowState.mComputedOffsets.left,
                     "Expected to solve for left");
        availWidth -= kidReflowState.mComputedOffsets.right;
      }
      if (availWidth < 0) {
        availWidth = 0;
      }

      // Shrink-to-fit: min(max(preferred minimum width, available width), preferred width).
      // XXX this is not completely correct - see bug 201897 comment 56/58 and bug 268499.
      if (kidDesiredSize.mMaxElementWidth > availWidth) {
        aKidFrame->DidReflow(aPresContext, &kidReflowState, NS_FRAME_REFLOW_FINISHED);
        availWidth = PR_MAX(0, kidDesiredSize.mMaxElementWidth -
                               kidReflowState.mComputedBorderPadding.left -
                               kidReflowState.mComputedBorderPadding.right);
        situation = SHRINK_TO_FIT_MEW;
        aReason = eReflowReason_Resize;
        continue; // Do a second reflow constrained to MEW.
      }
    }

    // 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);
    nsRect oldRect = aKidFrame->GetRect();
    aKidFrame->SetRect(rect);

    // Size and position the view and set its opacity, visibility, content
    // transparency, and clip
    nsContainerFrame::SyncFrameViewAfterReflow(aPresContext, aKidFrame,
                                               aKidFrame->GetView(),
                                               &kidDesiredSize.mOverflowArea);
    // if the frame moved, then the view would have invalidated everything so
    // we don't need to do any invalidation here.
    if (oldRect.TopLeft() == rect.TopLeft() &&
        aReason != eReflowReason_Initial &&
        oldRect.Size() != rect.Size()) {
      // Invalidate the area where the frame changed size. We can't
      // rely on the view to do this ... the view size might not change even
      // though the frame size changed (and besides, views will go away).
      // Invalidate the vertical strip
      nscoord innerWidth = PR_MIN(oldRect.width, rect.width);
      nscoord innerHeight = PR_MIN(oldRect.height, rect.height);
      nscoord outerWidth = PR_MAX(oldRect.width, rect.width);
      nscoord outerHeight = PR_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);

    // If the frame has visible overflow, then store it as a property on the
    // frame. This allows us to be able to recover it without having to reflow
    // the frame
    if (aKidFrame->GetStateBits() & NS_FRAME_OUTSIDE_CHILDREN) {
      // Get the property (creating a rect struct if necessary)
      nsRect* overflowArea = aKidFrame->GetOverflowAreaProperty(PR_TRUE);

      NS_ASSERTION(overflowArea, "should have created rect");
      if (overflowArea) {
        *overflowArea = kidDesiredSize.mOverflowArea;
      }
    }
#ifdef DEBUG
    if (nsBlockFrame::gNoisyReflow) {
      nsFrame::IndentBy(stdout,nsBlockFrame::gNoiseIndent - 1);
      printf("abs pos ");
      if (nsnull != aKidFrame) {
        nsIFrameDebug*  frameDebug;
        if (NS_SUCCEEDED(CallQueryInterface(aKidFrame, &frameDebug))) {
          nsAutoString name;
          frameDebug->GetFrameName(name);
          printf("%s ", NS_LossyConvertUTF16toASCII(name).get());
        }
      }
      printf("%p rect=%d,%d,%d,%d", aKidFrame, rect.x, rect.y, rect.width, rect.height);
      printf("\n");
    }
#endif

    break;
  }
  return rv;
}

#ifdef DEBUG
 void nsAbsoluteContainingBlock::PrettyUC(nscoord aSize,
                        char*   aBuf)
{
  if (NS_UNCONSTRAINEDSIZE == aSize) {
    strcpy(aBuf, "UC");
  }
  else {
    if((PRInt32)0xdeadbeef == aSize)
    {
      strcpy(aBuf, "deadbeef");
    }
    else {
      sprintf(aBuf, "%d", aSize);
    }
  }
}
#endif