gecko-dev/layout/generic/nsHTMLReflowState.cpp

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 *
 * The contents of this file are subject to the Netscape Public License
 * Version 1.0 (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/NPL/
 *
 * 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 Communicator client code.
 *
 * The Initial Developer of the Original Code is Netscape Communications
 * Corporation.  Portions created by Netscape are Copyright (C) 1998
 * Netscape Communications Corporation.  All Rights Reserved.
 */
#include "nsCOMPtr.h"
#include "nsIStyleContext.h"
#include "nsStyleConsts.h"
#include "nsFrame.h"
#include "nsIHTMLReflow.h"
#include "nsIContent.h"
#include "nsHTMLAtoms.h"
#include "nsIPresContext.h"
#include "nsIPresShell.h"
#include "nsLayoutAtoms.h"

#ifdef NS_DEBUG
#undef NOISY_VERTICAL_ALIGN
#else
#undef NOISY_VERTICAL_ALIGN
#endif

// Initialize a <b>root</b> reflow state with a rendering context to
// use for measuring things.
nsHTMLReflowState::nsHTMLReflowState(nsIPresContext&      aPresContext,
                                     nsIFrame*            aFrame,
                                     nsReflowReason       aReason,
                                     nsIRenderingContext* aRenderingContext,
                                     const nsSize&        aAvailableSpace)
{
  NS_PRECONDITION(nsnull != aRenderingContext, "no rendering context");

  parentReflowState = nsnull;
  frame = aFrame;
  reason = aReason;
  reflowCommand = nsnull;
  availableWidth = aAvailableSpace.width;
  availableHeight = aAvailableSpace.height;
  rendContext = aRenderingContext;
  isTopOfPage = PR_FALSE;
  Init(aPresContext);
}

// Initialize a <b>root</b> reflow state for an <b>incremental</b>
// reflow.
nsHTMLReflowState::nsHTMLReflowState(nsIPresContext&      aPresContext,
                                     nsIFrame*            aFrame,
                                     nsIReflowCommand&    aReflowCommand,
                                     nsIRenderingContext* aRenderingContext,
                                     const nsSize&        aAvailableSpace)
{
  NS_PRECONDITION(nsnull != aRenderingContext, "no rendering context");

  parentReflowState = nsnull;
  frame = aFrame;
  reason = eReflowReason_Incremental;
  reflowCommand = &aReflowCommand;
  availableWidth = aAvailableSpace.width;
  availableHeight = aAvailableSpace.height;
  rendContext = aRenderingContext;
  isTopOfPage = PR_FALSE;
  Init(aPresContext);
}

// Initialize a reflow state for a child frames reflow. Some state
// is copied from the parent reflow state; the remaining state is
// computed.
nsHTMLReflowState::nsHTMLReflowState(nsIPresContext&          aPresContext,
                                     const nsHTMLReflowState& aParentReflowState,
                                     nsIFrame*                aFrame,
                                     const nsSize&            aAvailableSpace,
                                     nsReflowReason           aReason)
{
  parentReflowState = &aParentReflowState;
  frame = aFrame;
  reason = aReason;
  reflowCommand = (reason == eReflowReason_Incremental)
    ? aParentReflowState.reflowCommand
    : nsnull;
  availableWidth = aAvailableSpace.width;
  availableHeight = aAvailableSpace.height;

  rendContext = aParentReflowState.rendContext;
  spaceManager = aParentReflowState.spaceManager;
  lineLayout = aParentReflowState.lineLayout;
  isTopOfPage = aParentReflowState.isTopOfPage;

  Init(aPresContext);
}

// Same as the previous except that the reason is taken from the
// parent's reflow state.
nsHTMLReflowState::nsHTMLReflowState(nsIPresContext&          aPresContext,
                                     const nsHTMLReflowState& aParentReflowState,
                                     nsIFrame*                aFrame,
                                     const nsSize&            aAvailableSpace)
{
  parentReflowState = &aParentReflowState;
  frame = aFrame;
  reason = aParentReflowState.reason;
  reflowCommand = aParentReflowState.reflowCommand;
  availableWidth = aAvailableSpace.width;
  availableHeight = aAvailableSpace.height;

  rendContext = aParentReflowState.rendContext;
  spaceManager = aParentReflowState.spaceManager;
  lineLayout = aParentReflowState.lineLayout;
  isTopOfPage = aParentReflowState.isTopOfPage;

  Init(aPresContext);
}

void
nsHTMLReflowState::Init(nsIPresContext& aPresContext)
{
  mRunInFrame = nsnull;
  mCompactMarginWidth = 0;
  mAlignCharOffset = 0;
  mUseAlignCharOffset = 0;

  frame->GetStyleData(eStyleStruct_Position,
                      (const nsStyleStruct*&)mStylePosition);
  frame->GetStyleData(eStyleStruct_Display,
                      (const nsStyleStruct*&)mStyleDisplay);
  frame->GetStyleData(eStyleStruct_Spacing,
                      (const nsStyleStruct*&)mStyleSpacing);
  frameType = DetermineFrameType(frame, mStylePosition, mStyleDisplay);
  InitConstraints(aPresContext);
}

PRBool
nsHTMLReflowState::HaveFixedContentWidth() const
{
  const nsStylePosition* pos;
  frame->GetStyleData(eStyleStruct_Position, (const nsStyleStruct*&)pos);
  // What about 'inherit'?
  return eStyleUnit_Auto != pos->mWidth.GetUnit();
}

PRBool
nsHTMLReflowState::HaveFixedContentHeight() const
{
  const nsStylePosition* pos;
  frame->GetStyleData(eStyleStruct_Position, (const nsStyleStruct*&)pos);
  // What about 'inherit'?
  return eStyleUnit_Auto != pos->mHeight.GetUnit();
}

const nsHTMLReflowState*
nsHTMLReflowState::GetContainingBlockReflowState(const nsReflowState* aParentRS)
{
  while (nsnull != aParentRS) {
    if (nsnull != aParentRS->frame) {
      PRBool isContainingBlock;
      // XXX This needs to go and we need to start using the info in the
      // reflow state...
      nsresult rv = aParentRS->frame->IsPercentageBase(isContainingBlock);
      if (NS_SUCCEEDED(rv) && isContainingBlock) {
        return (const nsHTMLReflowState*) aParentRS;
      }
    }
    aParentRS = aParentRS->parentReflowState;
  }
  return nsnull;
}

const nsHTMLReflowState*
nsHTMLReflowState::GetPageBoxReflowState(const nsReflowState* aParentRS)
{
  // XXX write me as soon as we can ask a frame if it's a page frame...
  return nsnull;
}

nscoord
nsHTMLReflowState::GetContainingBlockContentWidth(const nsReflowState* aParentRS)
{
  nscoord width = 0;
  const nsHTMLReflowState* rs =
    GetContainingBlockReflowState(aParentRS);
  if (nsnull != rs) {
    return ((nsHTMLReflowState*)aParentRS)->computedWidth;/* XXX cast */
  }
  return width;
}

nsCSSFrameType
nsHTMLReflowState::DetermineFrameType(nsIFrame* aFrame)
{
  const nsStylePosition* stylePosition;
  aFrame->GetStyleData(eStyleStruct_Position,
                       (const nsStyleStruct*&)stylePosition);
  const nsStyleDisplay* styleDisplay;
  aFrame->GetStyleData(eStyleStruct_Display,
                       (const nsStyleStruct*&)styleDisplay);
  return DetermineFrameType(aFrame, stylePosition, styleDisplay);
}

nsCSSFrameType
nsHTMLReflowState::DetermineFrameType(nsIFrame* aFrame,
                                      const nsStylePosition* aPosition,
                                      const nsStyleDisplay* aDisplay)
{
  nsCSSFrameType frameType;

  // Section 9.7 of the CSS2 spec indicates that absolute position
  // takes precedence over float which takes precedence over display.
  if (aPosition->IsAbsolutelyPositioned()) {
    frameType = NS_CSS_FRAME_TYPE_ABSOLUTE;
  }
  else if (NS_STYLE_FLOAT_NONE != aDisplay->mFloats) {
    frameType = NS_CSS_FRAME_TYPE_FLOATING;
  }
  else {
    switch (aDisplay->mDisplay) {
    case NS_STYLE_DISPLAY_BLOCK:
    case NS_STYLE_DISPLAY_LIST_ITEM:
    case NS_STYLE_DISPLAY_TABLE:
      frameType = NS_CSS_FRAME_TYPE_BLOCK;
      break;

    case NS_STYLE_DISPLAY_INLINE:
    case NS_STYLE_DISPLAY_MARKER:
    case NS_STYLE_DISPLAY_INLINE_TABLE:
      frameType = NS_CSS_FRAME_TYPE_INLINE;
      break;

    case NS_STYLE_DISPLAY_RUN_IN:
    case NS_STYLE_DISPLAY_COMPACT:
      // XXX need to look ahead at the frame's sibling
      frameType = NS_CSS_FRAME_TYPE_BLOCK;
      break;

    case NS_STYLE_DISPLAY_TABLE_CELL:
    case NS_STYLE_DISPLAY_TABLE_CAPTION:
    case NS_STYLE_DISPLAY_TABLE_ROW_GROUP:
    case NS_STYLE_DISPLAY_TABLE_COLUMN:
    case NS_STYLE_DISPLAY_TABLE_COLUMN_GROUP:
    case NS_STYLE_DISPLAY_TABLE_HEADER_GROUP:
    case NS_STYLE_DISPLAY_TABLE_FOOTER_GROUP:
    case NS_STYLE_DISPLAY_TABLE_ROW:
      frameType = NS_CSS_FRAME_TYPE_INTERNAL_TABLE;
      break;

    case NS_STYLE_DISPLAY_NONE:
    default:
      frameType = NS_CSS_FRAME_TYPE_UNKNOWN;
      break;
    }
  }

  // See if the frame is replaced
  nsFrameState  frameState;
  aFrame->GetFrameState(&frameState);
  if (frameState & NS_FRAME_REPLACED_ELEMENT) {
    frameType = NS_FRAME_REPLACED(frameType);
  }

  return frameType;
}

void
nsHTMLReflowState::ComputeRelativeOffsets(const nsHTMLReflowState* cbrs)
{
  nsStyleCoord              coord;
  const nsHTMLReflowState*  pcbrs = nsnull;

  // If any of the offsets are 'inherit' we need to find the positioned
  // containing block 
  if ((eStyleUnit_Inherit == mStylePosition->mOffset.GetLeftUnit()) ||
      (eStyleUnit_Inherit == mStylePosition->mOffset.GetTopUnit()) ||
      (eStyleUnit_Inherit == mStylePosition->mOffset.GetRightUnit()) ||
      (eStyleUnit_Inherit == mStylePosition->mOffset.GetBottomUnit())) {

    pcbrs = cbrs;

    while (nsnull != pcbrs) {
      const nsStylePosition* pcbrsPosition;
      pcbrs->frame->GetStyleData(eStyleStruct_Position,
                                 (const nsStyleStruct*&)pcbrsPosition);

      if ((NS_STYLE_POSITION_ABSOLUTE == pcbrsPosition->mPosition) ||
          (NS_STYLE_POSITION_RELATIVE == pcbrsPosition->mPosition)) {
        break;
      }

      pcbrs = (const nsHTMLReflowState*)pcbrs->parentReflowState;  // XXX cast
    }
  }

  // Compute the 'left' and 'right' values. 'Left' moves the boxes to the right,
  // and 'right' moves the boxes to the left. The computed values are always:
  // left=-right
  PRBool  leftIsAuto = eStyleUnit_Auto == mStylePosition->mOffset.GetLeftUnit();
  PRBool  rightIsAuto = eStyleUnit_Auto == mStylePosition->mOffset.GetRightUnit();

  // Check for percentage based values and an unconstrained containing
  // block width. Treat them like 'auto'
  if (NS_UNCONSTRAINEDSIZE == cbrs->computedWidth) {
    if (eStyleUnit_Percent == mStylePosition->mOffset.GetLeftUnit()) {
      leftIsAuto = PR_TRUE;
    }
    if (eStyleUnit_Percent == mStylePosition->mOffset.GetRightUnit()) {
      rightIsAuto = PR_TRUE;
    }
  }

  // If neither 'left' not 'right' are auto, then we're over-constrained and
  // we ignore one of them
  if (!leftIsAuto && !rightIsAuto) {
    const nsStyleDisplay* display;
    frame->GetStyleData(eStyleStruct_Display, (const nsStyleStruct*&)display);
    
    if (NS_STYLE_DIRECTION_LTR == display->mDirection) {
      rightIsAuto = PR_TRUE;
    } else {
      leftIsAuto = PR_TRUE;
    }
  }

  if (leftIsAuto) {
    if (rightIsAuto) {
      // If both are 'auto' (their initial values), the computed values are 0
      computedOffsets.left = computedOffsets.right = 0;
    } else {
      // 'Right' isn't 'auto' so compute its value
      if (eStyleUnit_Inherit == mStylePosition->mOffset.GetRightUnit()) {
        computedOffsets.right = pcbrs ? pcbrs->computedOffsets.right : 0;
      } else {
        ComputeHorizontalValue(cbrs->computedWidth, mStylePosition->mOffset.GetRightUnit(),
                               mStylePosition->mOffset.GetRight(coord),
                               computedOffsets.right);
      }
      
      // Computed value for 'left' is minus the value of 'right'
      computedOffsets.left = -computedOffsets.right;
    }

  } else {
    NS_ASSERTION(rightIsAuto, "unexpected specified constraint");
    
    // 'Left' isn't 'auto' so compute its value
    if (eStyleUnit_Inherit == mStylePosition->mOffset.GetLeftUnit()) {
      computedOffsets.left = pcbrs ? pcbrs->computedOffsets.left : 0;
    } else {
      ComputeHorizontalValue(cbrs->computedWidth, mStylePosition->mOffset.GetLeftUnit(),
                             mStylePosition->mOffset.GetLeft(coord),
                             computedOffsets.left);
    }

    // Computed value for 'right' is minus the value of 'left'
    computedOffsets.right = -computedOffsets.left;
  }

  // Compute the 'top' and 'bottom' values. The 'top' and 'bottom' properties
  // move relatively positioned elements up and down. They also must be each 
  // other's negative
  PRBool  topIsAuto = eStyleUnit_Auto == mStylePosition->mOffset.GetTopUnit();
  PRBool  bottomIsAuto = eStyleUnit_Auto == mStylePosition->mOffset.GetBottomUnit();

  // Check for percentage based values and a containing block height that
  // depends on the content height. Treat them like 'auto'
  if (NS_AUTOHEIGHT == cbrs->computedHeight) {
    if (eStyleUnit_Percent == mStylePosition->mOffset.GetTopUnit()) {
      topIsAuto = PR_TRUE;
    }
    if (eStyleUnit_Percent == mStylePosition->mOffset.GetBottomUnit()) {
      bottomIsAuto = PR_TRUE;
    }
  }

  // If neither is 'auto', 'bottom' is ignored
  if (!topIsAuto && !bottomIsAuto) {
    bottomIsAuto = PR_TRUE;
  }

  if (topIsAuto) {
    if (bottomIsAuto) {
      // If both are 'auto' (their initial values), the computed values are 0
      computedOffsets.top = computedOffsets.bottom = 0;
    } else {
      // 'Bottom' isn't 'auto' so compute its value
      if (eStyleUnit_Inherit == mStylePosition->mOffset.GetBottomUnit()) {
        computedOffsets.bottom = pcbrs ? pcbrs->computedOffsets.bottom : 0;
      } else {
        ComputeVerticalValue(cbrs->computedHeight, mStylePosition->mOffset.GetBottomUnit(),
                               mStylePosition->mOffset.GetBottom(coord),
                               computedOffsets.bottom);
      }
      
      // Computed value for 'top' is minus the value of 'bottom'
      computedOffsets.top = -computedOffsets.bottom;
    }

  } else {
    NS_ASSERTION(bottomIsAuto, "unexpected specified constraint");
    
    // 'Top' isn't 'auto' so compute its value
    if (eStyleUnit_Inherit == mStylePosition->mOffset.GetTopUnit()) {
      computedOffsets.top = pcbrs ? pcbrs->computedOffsets.top : 0;
    } else {
      ComputeVerticalValue(cbrs->computedHeight, mStylePosition->mOffset.GetTopUnit(),
                             mStylePosition->mOffset.GetTop(coord),
                             computedOffsets.top);
    }

    // Computed value for 'bottom' is minus the value of 'top'
    computedOffsets.bottom = -computedOffsets.top;
  }
}

void
nsHTMLReflowState::InitAbsoluteConstraints(nsIPresContext& aPresContext,
                                           const nsHTMLReflowState* cbrs,
                                           nscoord containingBlockWidth,
                                           nscoord containingBlockHeight)
{
  // If any of the offsets are 'auto', then get the placeholder frame
  // and compute its origin relative to the containing block
  nsPoint placeholderOffset(0, 0);
  if ((eStyleUnit_Auto == mStylePosition->mOffset.GetLeftUnit()) ||
      (eStyleUnit_Auto == mStylePosition->mOffset.GetTopUnit()) ||
      (eStyleUnit_Auto == mStylePosition->mOffset.GetRightUnit()) ||
      (eStyleUnit_Auto == mStylePosition->mOffset.GetBottomUnit())) {
    
    // Get the placeholder frame
    nsIFrame*     placeholderFrame;
    nsCOMPtr<nsIPresShell> presShell;
    aPresContext.GetShell(getter_AddRefs(presShell));

    presShell->GetPlaceholderFrameFor(frame, &placeholderFrame);
    NS_ASSERTION(nsnull != placeholderFrame, "no placeholder frame");
    if (nsnull != placeholderFrame) {
      placeholderFrame->GetOrigin(placeholderOffset);

      nsIFrame* parent;
      placeholderFrame->GetParent(&parent);
      while ((nsnull != parent) && (parent != cbrs->frame)) {
        nsPoint origin;

        parent->GetOrigin(origin);
        placeholderOffset += origin;
        parent->GetParent(&parent);
      }

      // Offsets are relative to the containing block's padding edge, so translate
      // from the frame's edge to the padding edge
      nsMargin              blockBorder;
      const nsStyleSpacing* blockSpacing;

      cbrs->frame->GetStyleData(eStyleStruct_Spacing, (const nsStyleStruct*&)blockSpacing);
      blockSpacing->GetBorder(blockBorder);
      placeholderOffset.x -= blockBorder.top;
      placeholderOffset.y -= blockBorder.bottom;
    }
  }

  nsStyleUnit widthUnit = mStylePosition->mWidth.GetUnit();
  nsStyleUnit heightUnit = mStylePosition->mHeight.GetUnit();

  // Initialize the 'left' and 'right' computed offsets
  PRBool        leftIsAuto = PR_FALSE, rightIsAuto = PR_FALSE;
  nsStyleCoord  coord;
  if (eStyleUnit_Inherit == mStylePosition->mOffset.GetLeftUnit()) {
    computedOffsets.left = cbrs->computedOffsets.left;
  } else if (eStyleUnit_Auto == mStylePosition->mOffset.GetLeftUnit()) {
    if (NS_STYLE_DIRECTION_LTR == mStyleDisplay->mDirection) {
      computedOffsets.left = placeholderOffset.x;
    } else {
      computedOffsets.left = 0;
      leftIsAuto = PR_TRUE;
    }
  } else {
    ComputeHorizontalValue(containingBlockWidth, mStylePosition->mOffset.GetLeftUnit(),
                           mStylePosition->mOffset.GetLeft(coord),
                           computedOffsets.left);
  }
  if (eStyleUnit_Inherit == mStylePosition->mOffset.GetRightUnit()) {
    computedOffsets.right = cbrs->computedOffsets.right;
  } else if (eStyleUnit_Auto == mStylePosition->mOffset.GetRightUnit()) {
    if (NS_STYLE_DIRECTION_RTL == mStyleDisplay->mDirection) {
      computedOffsets.right = placeholderOffset.x;
    } else {
      computedOffsets.right = 0;
      rightIsAuto = PR_TRUE;
    }
  } else {
    ComputeHorizontalValue(containingBlockWidth, mStylePosition->mOffset.GetRightUnit(),
                           mStylePosition->mOffset.GetRight(coord),
                           computedOffsets.right);
  }

  // Calculate the computed width
  if (eStyleUnit_Auto == widthUnit) {
    // Any remaining 'auto' values for 'left', 'right', 'margin-left', or
    // 'margin-right' are replaced with 0 (their default value)
    computedWidth = containingBlockWidth - computedOffsets.left -
      computedMargin.left - mComputedBorderPadding.left -
      mComputedBorderPadding.right -
      computedMargin.right - computedOffsets.right;
  } else {
    if (eStyleUnit_Inherit == widthUnit) {
      computedWidth = containingBlockWidth;
    } else {
      // Use the specified value for the computed width
      ComputeHorizontalValue(containingBlockWidth, widthUnit,
                             mStylePosition->mWidth, computedWidth);
    }

    if (leftIsAuto) {
      // Any 'auto' on 'margin-left' or 'margin-right' are replaced with 0
      // (their default value)
      computedOffsets.left = containingBlockWidth - computedMargin.left -
        mComputedBorderPadding.left - computedWidth -
        mComputedBorderPadding.right -
        computedMargin.right - computedOffsets.right;

    } else if (rightIsAuto) {
      // Any 'auto' on 'margin-left' or 'margin-right' are replaced with 0
      // (their default value)
      computedOffsets.right = containingBlockWidth - computedOffsets.left -
        computedMargin.left - mComputedBorderPadding.left - computedWidth -
        mComputedBorderPadding.right - computedMargin.right;

    } else {
      // All that's left to solve for are 'auto' values for 'margin-left' and
      // 'margin-right'
      if ((eStyleUnit_Auto == mStyleSpacing->mMargin.GetLeftUnit()) ||
          (eStyleUnit_Auto == mStyleSpacing->mMargin.GetRightUnit())) {

        nscoord availMarginSpace = containingBlockWidth -
          computedOffsets.left - mComputedBorderPadding.left -
          computedWidth - mComputedBorderPadding.right -
          computedOffsets.right;

        if (eStyleUnit_Auto == mStyleSpacing->mMargin.GetLeftUnit()) {
          if (eStyleUnit_Auto == mStyleSpacing->mMargin.GetRightUnit()) {
            // Both 'margin-left' and 'margin-right' are 'auto', so they get
            // equal values
            computedMargin.left = availMarginSpace / 2;
            computedMargin.right = availMarginSpace - computedMargin.left;
          } else {
            computedMargin.left = availMarginSpace;
          }
        } else {
          computedMargin.right = availMarginSpace;
        }
      }
    }
  }

  // Initialize the 'top' and 'bottom' computed offsets
  PRBool  bottomIsAuto = PR_FALSE;
  if (eStyleUnit_Inherit == mStylePosition->mOffset.GetTopUnit()) {
    computedOffsets.top = cbrs->computedOffsets.top;
  } else if ((eStyleUnit_Auto == mStylePosition->mOffset.GetTopUnit()) ||
      ((NS_AUTOHEIGHT == containingBlockHeight) &&
       (eStyleUnit_Percent == mStylePosition->mOffset.GetTopUnit()))) {
    // Use the placeholder position
    computedOffsets.top = placeholderOffset.y;
  } else {
    nsStyleCoord  coord;
    ComputeVerticalValue(containingBlockHeight, mStylePosition->mOffset.GetTopUnit(),
                         mStylePosition->mOffset.GetTop(coord), computedOffsets.top);
  }
  if (eStyleUnit_Inherit == mStylePosition->mOffset.GetBottomUnit()) {
    computedOffsets.bottom = cbrs->computedOffsets.bottom;
  } else if ((eStyleUnit_Auto == mStylePosition->mOffset.GetBottomUnit()) ||
      ((NS_AUTOHEIGHT == containingBlockHeight) &&
       (eStyleUnit_Percent == mStylePosition->mOffset.GetBottomUnit()))) {
    if (eStyleUnit_Auto == heightUnit) {
      computedOffsets.bottom = 0;        
    } else {
      bottomIsAuto = PR_TRUE;
    }
  } else {
    nsStyleCoord  coord;
    ComputeVerticalValue(containingBlockHeight, mStylePosition->mOffset.GetBottomUnit(),
                         mStylePosition->mOffset.GetBottom(coord), computedOffsets.bottom);
  }

  // Check for a percentage based height and a containing block height
  // that depends on its content height, i.e., not explicitly specified
  if (eStyleUnit_Percent == heightUnit) {
    if (NS_AUTOHEIGHT == containingBlockHeight) {
      // Interpret the height like 'auto'
      heightUnit = eStyleUnit_Auto;
    }
  }

  // Calculate the computed height
  if (eStyleUnit_Auto == heightUnit) {
    // Any 'auto' on 'margin-top' or 'margin-bottom' are replaced with 0
    // (their default value)
    if (NS_FRAME_IS_REPLACED(frameType)) {
      computedHeight = NS_INTRINSICSIZE;
    } else {
      // If the containing block's height was not explicitly specified (i.e.,
      // it depends on its content height), then so does our height
      if (NS_AUTOHEIGHT == containingBlockHeight) {
        computedHeight = NS_AUTOHEIGHT;

      } else {
        computedHeight = containingBlockHeight - computedOffsets.top - 
          computedMargin.top - mComputedBorderPadding.top -
          mComputedBorderPadding.bottom -
          computedMargin.bottom - computedOffsets.bottom;
      }
    }
  } else {
    if (eStyleUnit_Inherit == heightUnit) {
      computedHeight = containingBlockHeight;
    } else {
      // Use the specified value for the computed height
      ComputeVerticalValue(containingBlockHeight, heightUnit,
                           mStylePosition->mHeight, computedHeight);
    }

    if (NS_AUTOHEIGHT != containingBlockHeight) {
      if (bottomIsAuto) {
        // Any 'auto' on 'margin-top' or 'margin-bottom' are replaced with 0
        computedOffsets.bottom = containingBlockHeight - computedOffsets.top -
          computedMargin.top - mComputedBorderPadding.top - computedHeight -
          mComputedBorderPadding.bottom - computedMargin.bottom;
  
      } else {
        // All that's left to solve for are 'auto' values for 'margin-top' and
        // 'margin-bottom'
        if ((eStyleUnit_Auto == mStyleSpacing->mMargin.GetTopUnit()) ||
            (eStyleUnit_Auto == mStyleSpacing->mMargin.GetBottomUnit())) {
  
          nscoord availMarginSpace = containingBlockHeight - computedOffsets.top -
            mComputedBorderPadding.top - computedHeight - mComputedBorderPadding.bottom -
            computedOffsets.bottom;
  
          if (eStyleUnit_Auto == mStyleSpacing->mMargin.GetTopUnit()) {
            if (eStyleUnit_Auto == mStyleSpacing->mMargin.GetBottomUnit()) {
              // Both 'margin-top' and 'margin-bottom' are 'auto', so they get
              // equal values
              computedMargin.top = availMarginSpace / 2;
              computedMargin.bottom = availMarginSpace - computedMargin.top;
            } else {
              computedMargin.top = availMarginSpace;
            }
          } else {
            computedMargin.bottom = availMarginSpace;
          }
        }
      }
    }
  }
}

// XXX refactor this code to have methods for each set of properties
// we are computing: width,height,line-height; margin; offsets

void
nsHTMLReflowState::InitConstraints(nsIPresContext& aPresContext)
{
  // If this is the root frame then set the computed width and
  // height equal to the available space
  if (nsnull == parentReflowState) {
    computedWidth = availableWidth;
    computedHeight = availableHeight;
    computedMargin.SizeTo(0, 0, 0, 0);
    mComputedPadding.SizeTo(0, 0, 0, 0);
    mComputedBorderPadding.SizeTo(0, 0, 0, 0);
    computedOffsets.SizeTo(0, 0, 0, 0);
    mComputedMinWidth = mComputedMinHeight = 0;
    mComputedMaxWidth = mComputedMaxHeight = NS_UNCONSTRAINEDSIZE;
  } else {
    // Get the containing block reflow state
    const nsHTMLReflowState* cbrs =
      GetContainingBlockReflowState(parentReflowState);
    NS_ASSERTION(nsnull != cbrs, "no containing block");

    // See if the element is relatively positioned
    if (NS_STYLE_POSITION_RELATIVE == mStylePosition->mPosition) {
      ComputeRelativeOffsets(cbrs);
    } else {
      // Initialize offsets to 0
      computedOffsets.SizeTo(0, 0, 0, 0);
    }

    // Get the containing block width and height. We'll need them when
    // calculating the computed width and height. For all elements other
    // than absolutely positioned elements, the containing block is formed
    // by the content edge
    nscoord containingBlockWidth = cbrs->computedWidth;
    nscoord containingBlockHeight = cbrs->computedHeight;
    if (NS_FRAME_GET_TYPE(frameType) == NS_CSS_FRAME_TYPE_ABSOLUTE) {
      // Containing block is formed by the padding edge and not the padding edge
      containingBlockWidth += cbrs->mComputedPadding.left +
                              cbrs->mComputedPadding.right;
      containingBlockHeight += cbrs->mComputedPadding.top +
                               cbrs->mComputedPadding.bottom;
    }
#if 0
    nsFrame::ListTag(stdout, frame); printf(": cb=");
    nsFrame::ListTag(stdout, cbrs->frame); printf(" size=%d,%d\n", containingBlockWidth, containingBlockHeight);
#endif

    // See if the containing block height is based on the size of the
    // content
    if (NS_AUTOHEIGHT == containingBlockHeight) {
      // See if the containing block is a scrolled frame, i.e. its
      // parent is a scroll frame. The prescence of the interveening
      // frame (that the scroll frame scrolls) needs to be hidden from
      // the containingBlockHeight calcuation.
      if (cbrs->parentReflowState) {
        nsIFrame* f = cbrs->parentReflowState->frame;
        nsIAtom*  frameType;

        f->GetFrameType(&frameType);
        if (nsLayoutAtoms::scrollFrame == frameType) {
          // Use the scroll frame's computed height instead
          containingBlockHeight =
            ((nsHTMLReflowState*)cbrs->parentReflowState)->computedHeight;
        }
        NS_IF_RELEASE(frameType);
      }
    }

    // Compute margins from the specified margin style information. These
    // become the default computed values, and may be adjusted below
    // XXX fix to provide 0,0 for the top&bottom margins for
    // inline-non-replaced elements
    ComputeMargin(containingBlockWidth);
#ifdef DEBUG_kipp
    NS_ASSERTION((computedMargin.left > -200000) &&
                 (computedMargin.left < 200000), "oy");
    NS_ASSERTION((computedMargin.right > -200000) &&
                 (computedMargin.right < 200000), "oy");
#endif
    ComputePadding(containingBlockWidth);
    if (!mStyleSpacing->GetBorder(mComputedBorderPadding)) {
      // CSS2 has no percentage borders
      mComputedBorderPadding.SizeTo(0, 0, 0, 0);
    }
    mComputedBorderPadding += mComputedPadding;

    nsStyleUnit widthUnit = mStylePosition->mWidth.GetUnit();
    nsStyleUnit heightUnit = mStylePosition->mHeight.GetUnit();

    // Check for a percentage based width and an unconstrained containing
    // block width
    if (eStyleUnit_Percent == widthUnit) {
      if (NS_UNCONSTRAINEDSIZE == containingBlockWidth) {
        // Interpret the width like 'auto'
        widthUnit = eStyleUnit_Auto;
      }
    }
    // Check for a percentage based height and a containing block height
    // that depends on the content height
    if (eStyleUnit_Percent == heightUnit) {
      if (NS_AUTOHEIGHT == containingBlockHeight) {
        // Interpret the height like 'auto'
        heightUnit = eStyleUnit_Auto;
      }
    }

    // Calculate the computed values for min and max properties
    ComputeMinMaxValues(containingBlockWidth, containingBlockHeight, cbrs);

    // Calculate the computed width and height. This varies by frame type
    if ((NS_FRAME_REPLACED(NS_CSS_FRAME_TYPE_INLINE) == frameType) ||
        (NS_FRAME_REPLACED(NS_CSS_FRAME_TYPE_FLOATING) == frameType)) {
      // Inline replaced element and floating replaced element are basically
      // treated the same
      if (eStyleUnit_Inherit == widthUnit) {
        computedWidth = containingBlockWidth;
      } else if (eStyleUnit_Auto == widthUnit) {
        // A specified value of 'auto' uses the element's intrinsic width
        computedWidth = NS_INTRINSICSIZE;
      } else {
        ComputeHorizontalValue(containingBlockWidth, widthUnit,
                               mStylePosition->mWidth,
                               computedWidth);
      }
      if (eStyleUnit_Inherit == heightUnit) {
        computedHeight = containingBlockHeight;
      } else if (eStyleUnit_Auto == heightUnit) {
        // A specified value of 'auto' uses the element's intrinsic height
        computedHeight = NS_INTRINSICSIZE;
      } else {
        ComputeVerticalValue(containingBlockHeight, heightUnit,
                             mStylePosition->mHeight,
                             computedHeight);
      }
    } else if (NS_CSS_FRAME_TYPE_FLOATING == frameType) {
      // Floating non-replaced element
      if (eStyleUnit_Inherit == widthUnit) {
        computedWidth = containingBlockWidth;
      } else if (eStyleUnit_Auto == widthUnit) {
        // A specified value of 'auto' becomes a computed width of 0
        computedWidth = 0;
      } else {
        ComputeHorizontalValue(containingBlockWidth, widthUnit,
                               mStylePosition->mWidth,
                               computedWidth);
      }
      if (eStyleUnit_Inherit == heightUnit) {
        computedHeight = containingBlockHeight;
      } else if (eStyleUnit_Auto == heightUnit) {
        computedHeight = NS_AUTOHEIGHT;  // let it choose its height
      } else {
        ComputeVerticalValue(containingBlockHeight, heightUnit,
                             mStylePosition->mHeight,
                             computedHeight);
      }
    } else if (NS_CSS_FRAME_TYPE_INTERNAL_TABLE == frameType) {
      // Internal table elements. The rules vary depending on the type
      // Calculate the computed width
      if ((NS_STYLE_DISPLAY_TABLE_ROW == mStyleDisplay->mDisplay) ||
          (NS_STYLE_DISPLAY_TABLE_ROW_GROUP == mStyleDisplay->mDisplay)) {
        // 'width' property doesn't apply to table rows and row groups
        widthUnit = eStyleUnit_Auto;
      }

      if (eStyleUnit_Inherit == widthUnit) {
        computedWidth = containingBlockWidth;
      } else if (eStyleUnit_Auto == widthUnit) {
        computedWidth = availableWidth;

        if (computedWidth != NS_UNCONSTRAINEDSIZE) {
          // Internal table elements don't have margins, but they have border
          // and padding
          computedWidth -= mComputedBorderPadding.left +
            mComputedBorderPadding.right;
        }
      
      } else {
        ComputeHorizontalValue(containingBlockWidth, widthUnit,
                               mStylePosition->mWidth,
                               computedWidth);
      }

      // Calculate the computed height
      if ((NS_STYLE_DISPLAY_TABLE_COLUMN == mStyleDisplay->mDisplay) ||
          (NS_STYLE_DISPLAY_TABLE_COLUMN_GROUP == mStyleDisplay->mDisplay)) {
        // 'height' property doesn't apply to table columns and column groups
        heightUnit = eStyleUnit_Auto;
      }
      if (eStyleUnit_Inherit == heightUnit) {
        computedHeight = containingBlockHeight;
      } else if (eStyleUnit_Auto == heightUnit) {
        computedHeight = NS_AUTOHEIGHT;
      } else {
        ComputeVerticalValue(containingBlockHeight, heightUnit,
                             mStylePosition->mHeight,
                             computedHeight);
      }

      // Doesn't apply to table elements
      mComputedMinWidth = mComputedMinHeight = 0;
      mComputedMaxWidth = mComputedMaxHeight = NS_UNCONSTRAINEDSIZE;

    } else if (NS_FRAME_GET_TYPE(frameType) == NS_CSS_FRAME_TYPE_ABSOLUTE) {
      InitAbsoluteConstraints(aPresContext, cbrs, containingBlockWidth,
                              containingBlockHeight);
    } else if (NS_CSS_FRAME_TYPE_INLINE == frameType) {
      // Inline non-replaced elements do not have computed widths or heights
      // XXX add this check to HaveFixedContentHeight/Width too
      computedWidth = NS_UNCONSTRAINEDSIZE;
      computedHeight = NS_UNCONSTRAINEDSIZE;
      computedMargin.top = 0;
      computedMargin.bottom = 0;
      mComputedMinWidth = mComputedMinHeight = 0;
      mComputedMaxWidth = mComputedMaxHeight = NS_UNCONSTRAINEDSIZE;
    } else {
      ComputeBlockBoxData(aPresContext, cbrs, widthUnit, heightUnit,
                          containingBlockWidth,
                          containingBlockHeight);
    }
  }
}

// Compute the box data for block and block-replaced elements in the
// normal flow.
void
nsHTMLReflowState::ComputeBlockBoxData(nsIPresContext& aPresContext,
                                       const nsHTMLReflowState* cbrs,
                                       nsStyleUnit aWidthUnit,
                                       nsStyleUnit aHeightUnit,
                                       nscoord aContainingBlockWidth,
                                       nscoord aContainingBlockHeight)
{
  // Compute the content width
  if (eStyleUnit_Auto == aWidthUnit) {
    if (NS_FRAME_IS_REPLACED(frameType)) {
      // Block-level replaced element in the flow. A specified value of 
      // 'auto' uses the element's intrinsic width
      computedWidth = NS_INTRINSICSIZE;
    } else {
      // Block-level non-replaced element in the flow
      if (NS_UNCONSTRAINEDSIZE == availableWidth) {
        computedWidth = NS_UNCONSTRAINEDSIZE;
      } else {
        // Block-level non-replaced element in the flow. 'auto'
        // values for margin-left and margin-right become 0 and the
        // sum of the areas must equal the width of the content-area
        // of the parent element.
        computedWidth = availableWidth - computedMargin.left -
          computedMargin.right - mComputedBorderPadding.left -
          mComputedBorderPadding.right;
      }
    }
  } else {
    if (eStyleUnit_Inherit == aWidthUnit) {
      // Use parent elements width. Note that if its width was
      // 'inherit', then it already did this so we don't need to
      // recurse upwards.
      //
      // We use the containing blocks width here for the "parent"
      // elements width, because we want to skip over any intervening
      // inline elements (since width doesn't apply to them).
      if (NS_UNCONSTRAINEDSIZE != aContainingBlockWidth) {
        computedWidth = aContainingBlockWidth;
      }
      else {
        computedWidth = NS_UNCONSTRAINEDSIZE;
      }
    }
    else {
      ComputeHorizontalValue(aContainingBlockWidth, aWidthUnit,
                             mStylePosition->mWidth, computedWidth);
    }

    // Calculate the computed left and right margin again taking into
    // account the computed width, border/padding, and width of the
    // containing block
    CalculateLeftRightMargin(cbrs, computedWidth);
  }
  
  // Compute the content height
  if (eStyleUnit_Inherit == aHeightUnit) {
    // Use parent elements height (note that if its height was inherit
    // then it already did this so we don't need to recurse upwards).
    //
    // We use the containing blocks height here for the "parent"
    // elements height because we want to skip over any interveening
    // inline elements (since height doesn't apply to them).
    if (NS_UNCONSTRAINEDSIZE != aContainingBlockHeight) {
      computedHeight = aContainingBlockHeight;
    }
    else {
      computedHeight = NS_UNCONSTRAINEDSIZE;
    }
  } else if (eStyleUnit_Auto == aHeightUnit) {
    if (NS_FRAME_IS_REPLACED(frameType)) {
      // For replaced elements use the intrinsic size for "auto"
      computedHeight = NS_INTRINSICSIZE;
    } else {
      // For non-replaced elements auto means unconstrained
      computedHeight = NS_UNCONSTRAINEDSIZE;
    }
  } else {
    ComputeVerticalValue(aContainingBlockHeight, aHeightUnit,
                         mStylePosition->mHeight, computedHeight);
  }
}

// Helper function that re-calculates the left and right margin based on
// the width of the containing block, the border/padding, and the computed
// width.
//
// This function is called by InitConstraints() when the 'width' property
// has a value other than 'auto'
void
nsHTMLReflowState::CalculateLeftRightMargin(const nsHTMLReflowState* cbrs,
                                            nscoord aComputedWidth)
{
  // We can only provide values for auto side margins in a constrained
  // reflow. For unconstrained reflow there is no effective width to
  // compute against...
  if ((NS_UNCONSTRAINEDSIZE != aComputedWidth) && 
      (NS_UNCONSTRAINEDSIZE != cbrs->computedWidth)) {

    PRBool isAutoLeftMargin = eStyleUnit_Auto == mStyleSpacing->mMargin.GetLeftUnit();
    PRBool isAutoRightMargin = eStyleUnit_Auto == mStyleSpacing->mMargin.GetRightUnit();

    // Calculate how much space is available for margins
    nscoord availMarginSpace = cbrs->computedWidth - aComputedWidth -
      mComputedBorderPadding.left - mComputedBorderPadding.right;

    // See whether we're over constrained
    if (!isAutoLeftMargin && !isAutoRightMargin) {
      // Neither margin is 'auto' so we're over constrained. Use the
      // 'direction' property to tell which margin to ignore
      if (NS_STYLE_DIRECTION_LTR == mStyleDisplay->mDirection) {
        isAutoRightMargin = PR_TRUE;
      } else {
        isAutoLeftMargin = PR_TRUE;
      }
    }

    if (isAutoLeftMargin) {
      if (isAutoRightMargin) {
        // Both margins are 'auto' so their computed values are equal
        computedMargin.left = availMarginSpace / 2;
        computedMargin.right = availMarginSpace - computedMargin.left;
      } else {
        computedMargin.left = availMarginSpace - computedMargin.right;
      }

    } else if (isAutoRightMargin) {
      computedMargin.right = availMarginSpace - computedMargin.left;
    }
#ifdef DEBUG_kipp
    NS_ASSERTION((computedMargin.left > -200000) &&
                 (computedMargin.left < 200000), "oy");
    NS_ASSERTION((computedMargin.right > -200000) &&
                 (computedMargin.right < 200000), "oy");
#endif
  }
}

nscoord
nsHTMLReflowState::CalcLineHeight(nsIPresContext& aPresContext,
                                  nsIFrame* aFrame)
{
  nscoord lineHeight = -1;
  nsIStyleContext* sc;
  aFrame->GetStyleContext(&sc);
  const nsStyleFont* elementFont = nsnull;
  if (nsnull != sc) {
    elementFont = (const nsStyleFont*)sc->GetStyleData(eStyleStruct_Font);
    for (;;) {
      const nsStyleText* text = (const nsStyleText*)
        sc->GetStyleData(eStyleStruct_Text);
      if (nsnull != text) {
        nsStyleUnit unit = text->mLineHeight.GetUnit();
        if (eStyleUnit_Enumerated == unit) {
          // Normal value; we use 1.0 for normal
          // XXX could come from somewhere else
#ifdef NOISY_VERTICAL_ALIGN
          printf("  line-height: normal\n");
#endif
          break;
        } else if (eStyleUnit_Factor == unit) {
          if (nsnull != elementFont) {
            // CSS2 spec says that the number is inherited, not the
            // computed value. Therefore use the font size of the
            // element times the inherited number.
            nscoord size = elementFont->mFont.size;
            lineHeight = nscoord(size * text->mLineHeight.GetFactorValue());
#ifdef NOISY_VERTICAL_ALIGN
            printf("  line-height: factor=%g result=%d\n",
                   text->mLineHeight.GetFactorValue(), lineHeight);
#endif
          }
          break;
        }
        else if (eStyleUnit_Coord == unit) {
          lineHeight = text->mLineHeight.GetCoordValue();
          break;
        }
        else if (eStyleUnit_Percent == unit) {
          // XXX This could arguably be the font-metrics actual height
          // instead since the spec says use the computed height.
          const nsStyleFont* font = (const nsStyleFont*)
            sc->GetStyleData(eStyleStruct_Font);
          nscoord size = font->mFont.size;
          lineHeight = nscoord(size * text->mLineHeight.GetPercentValue());
          break;
        }
        else if (eStyleUnit_Inherit == unit) {
          nsIStyleContext* parentSC;
          parentSC = sc->GetParent();
          if (nsnull == parentSC) {
            // Note: Break before releasing to avoid double-releasing sc
            break;
          }
          NS_RELEASE(sc);
          sc = parentSC;
        }
        else {
          // other units are not part of the spec so don't bother
          // looping
          break;
        }
      }
    }
    NS_RELEASE(sc);
  }

  return lineHeight;
}

void
nsHTMLReflowState::ComputeHorizontalValue(nscoord aContainingBlockWidth,
                                          nsStyleUnit aUnit,
                                          const nsStyleCoord& aCoord,
                                          nscoord& aResult)
{
  NS_PRECONDITION(eStyleUnit_Inherit != aUnit, "unexpected unit");
  aResult = 0;
  if (eStyleUnit_Percent == aUnit) {
    float pct = aCoord.GetPercentValue();
    aResult = NSToCoordFloor(aContainingBlockWidth * pct);
  
  } else if (eStyleUnit_Coord == aUnit) {
    aResult = aCoord.GetCoordValue();
  }
}

void
nsHTMLReflowState::ComputeVerticalValue(nscoord aContainingBlockHeight,
                                        nsStyleUnit aUnit,
                                        const nsStyleCoord& aCoord,
                                        nscoord& aResult)
{
  NS_PRECONDITION(eStyleUnit_Inherit != aUnit, "unexpected unit");
  aResult = 0;
  if (eStyleUnit_Percent == aUnit) {
    // Verify no one is trying to calculate a percentage based height against
    // a height that's shrink wrapping to its content. In that case they should
    // treat the specified value like 'auto'
    NS_ASSERTION(NS_AUTOHEIGHT != aContainingBlockHeight, "unexpected containing block height");
    float pct = aCoord.GetPercentValue();
    aResult = NSToCoordFloor(aContainingBlockHeight * pct);

  } else if (eStyleUnit_Coord == aUnit) {
    aResult = aCoord.GetCoordValue();
  }
}

void
nsHTMLReflowState::ComputeMarginFor(nsIFrame* aFrame,
                                    const nsReflowState* aParentRS,
                                    nsMargin& aResult)
{
  const nsStyleSpacing* spacing;
  nsresult rv;
  rv = aFrame->GetStyleData(eStyleStruct_Spacing,
                            (const nsStyleStruct*&) spacing);
  if (NS_SUCCEEDED(rv) && (nsnull != spacing)) {
    // If style style can provide us the margin directly, then use it.
#if 0
    if (!spacing->GetMargin(aResult) && (nsnull != aParentRS))
#else
    spacing->CalcMarginFor(aFrame, aResult);
    if ((eStyleUnit_Percent == spacing->mMargin.GetTopUnit()) ||
        (eStyleUnit_Percent == spacing->mMargin.GetRightUnit()) ||
        (eStyleUnit_Percent == spacing->mMargin.GetBottomUnit()) ||
        (eStyleUnit_Percent == spacing->mMargin.GetLeftUnit()))
#endif
    {
      // We have to compute the value (because it's uncomputable by
      // the style code).
      const nsHTMLReflowState* rs = GetContainingBlockReflowState(aParentRS);
      if (nsnull != rs) {
        nsStyleCoord left, right;
        nscoord containingBlockWidth = rs->computedWidth;
        if (NS_UNCONSTRAINEDSIZE == containingBlockWidth) {
          aResult.left = 0;
          aResult.right = 0;

        } else {
          ComputeHorizontalValue(containingBlockWidth, spacing->mMargin.GetLeftUnit(),
                                 spacing->mMargin.GetLeft(left), aResult.left);
          ComputeHorizontalValue(containingBlockWidth, spacing->mMargin.GetRightUnit(),
                                 spacing->mMargin.GetRight(right),
                                 aResult.right);
        }
      }
      else {
        aResult.left = 0;
        aResult.right = 0;
      }

      const nsHTMLReflowState* rs2 = GetPageBoxReflowState(aParentRS);
      nsStyleCoord top, bottom;
      if (nsnull != rs2) {
        // According to the CSS2 spec, margin percentages are
        // calculated with respect to the *height* of the containing
        // block when in a paginated context.
        ComputeVerticalValue(rs2->computedHeight, spacing->mMargin.GetTopUnit(),
                             spacing->mMargin.GetTop(top), aResult.top);
        ComputeVerticalValue(rs2->computedHeight, spacing->mMargin.GetBottomUnit(),
                             spacing->mMargin.GetBottom(bottom),
                             aResult.bottom);
      }
      else if (nsnull != rs) {
        // According to the CSS2 spec, margin percentages are
        // calculated with respect to the *width* of the containing
        // block, even for margin-top and margin-bottom.
        nscoord containingBlockWidth = rs->computedWidth;
        if (NS_UNCONSTRAINEDSIZE == containingBlockWidth) {
          aResult.top = 0;
          aResult.bottom = 0;

        } else {
          ComputeHorizontalValue(containingBlockWidth, spacing->mMargin.GetTopUnit(),
                                 spacing->mMargin.GetTop(top), aResult.top);
          ComputeHorizontalValue(containingBlockWidth, spacing->mMargin.GetBottomUnit(),
                                 spacing->mMargin.GetBottom(bottom),
                                 aResult.bottom);
        }
      }
      else {
        aResult.top = 0;
        aResult.bottom = 0;
      }
    }
  }
}

void
nsHTMLReflowState::ComputeMargin(nscoord aContainingBlockWidth)
{
  // If style style can provide us the margin directly, then use it.
#if 0
  if (!mStyleSpacing->GetMargin(aResult) && (nsnull != aParentRS))
#else
  mStyleSpacing->CalcMarginFor(frame, computedMargin);
  if ((eStyleUnit_Percent == mStyleSpacing->mMargin.GetTopUnit()) ||
      (eStyleUnit_Percent == mStyleSpacing->mMargin.GetRightUnit()) ||
      (eStyleUnit_Percent == mStyleSpacing->mMargin.GetBottomUnit()) ||
      (eStyleUnit_Percent == mStyleSpacing->mMargin.GetLeftUnit()))
#endif
  {
    // We have to compute the value (because it's uncomputable by
    // the style code).
    if (NS_UNCONSTRAINEDSIZE == aContainingBlockWidth) {
      computedMargin.left = 0;
      computedMargin.right = 0;

    } else {
      nsStyleCoord left, right;
      ComputeHorizontalValue(aContainingBlockWidth,
                             mStyleSpacing->mMargin.GetLeftUnit(),
                             mStyleSpacing->mMargin.GetLeft(left),
                             computedMargin.left);
      ComputeHorizontalValue(aContainingBlockWidth,
                             mStyleSpacing->mMargin.GetRightUnit(),
                             mStyleSpacing->mMargin.GetRight(right),
                             computedMargin.right);
    }

    const nsHTMLReflowState* rs2 = GetPageBoxReflowState(parentReflowState);
    nsStyleCoord top, bottom;
    if (nsnull != rs2) {
      // According to the CSS2 spec, margin percentages are
      // calculated with respect to the *height* of the containing
      // block when in a paginated context.
      ComputeVerticalValue(rs2->computedHeight,
                           mStyleSpacing->mMargin.GetTopUnit(),
                           mStyleSpacing->mMargin.GetTop(top),
                           computedMargin.top);
      ComputeVerticalValue(rs2->computedHeight,
                           mStyleSpacing->mMargin.GetBottomUnit(),
                           mStyleSpacing->mMargin.GetBottom(bottom),
                           computedMargin.bottom);
    }
    else {
      // According to the CSS2 spec, margin percentages are
      // calculated with respect to the *width* of the containing
      // block, even for margin-top and margin-bottom.
      if (NS_UNCONSTRAINEDSIZE == aContainingBlockWidth) {
        computedMargin.top = 0;
        computedMargin.bottom = 0;

      } else {
        ComputeHorizontalValue(aContainingBlockWidth,
                               mStyleSpacing->mMargin.GetTopUnit(),
                               mStyleSpacing->mMargin.GetTop(top),
                               computedMargin.top);
        ComputeHorizontalValue(aContainingBlockWidth,
                               mStyleSpacing->mMargin.GetBottomUnit(),
                               mStyleSpacing->mMargin.GetBottom(bottom),
                               computedMargin.bottom);
      }
    }
  }
}

void
nsHTMLReflowState::ComputePadding(nscoord aContainingBlockWidth)
{
  // If style can provide us the padding directly, then use it.
#if 0
  if (!mStyleSpacing->GetPadding(mComputedPadding))
#else
  mStyleSpacing->CalcPaddingFor(frame, mComputedPadding);
  if ((eStyleUnit_Percent == mStyleSpacing->mPadding.GetTopUnit()) ||
      (eStyleUnit_Percent == mStyleSpacing->mPadding.GetRightUnit()) ||
      (eStyleUnit_Percent == mStyleSpacing->mPadding.GetBottomUnit()) ||
      (eStyleUnit_Percent == mStyleSpacing->mPadding.GetLeftUnit()))
#endif
  {
    // We have to compute the value (because it's uncomputable by
    // the style code).
    nsStyleCoord left, right, top, bottom;
    ComputeHorizontalValue(aContainingBlockWidth,
                           mStyleSpacing->mPadding.GetLeftUnit(),
                           mStyleSpacing->mPadding.GetLeft(left),
                           mComputedPadding.left);
    ComputeHorizontalValue(aContainingBlockWidth,
                           mStyleSpacing->mPadding.GetRightUnit(),
                           mStyleSpacing->mPadding.GetRight(right),
                           mComputedPadding.right);

    // According to the CSS2 spec, padding percentages are
    // calculated with respect to the *width* of the containing
    // block, even for padding-top and padding-bottom.
    ComputeHorizontalValue(aContainingBlockWidth,
                           mStyleSpacing->mPadding.GetTopUnit(),
                           mStyleSpacing->mPadding.GetTop(top),
                           mComputedPadding.top);
    ComputeHorizontalValue(aContainingBlockWidth,
                           mStyleSpacing->mPadding.GetBottomUnit(),
                           mStyleSpacing->mPadding.GetBottom(bottom),
                           mComputedPadding.bottom);
  }
}

void
nsHTMLReflowState::ComputeBorderPaddingFor(nsIFrame* aFrame,
                                           const nsReflowState* aParentRS,
                                           nsMargin& aResult)
{
  const nsStyleSpacing* spacing;
  nsresult rv;
  rv = aFrame->GetStyleData(eStyleStruct_Spacing,
                            (const nsStyleStruct*&) spacing);
  if (NS_SUCCEEDED(rv) && (nsnull != spacing)) {
    nsMargin b, p;

    // If style style can provide us the margin directly, then use it.
    if (!spacing->GetBorder(b)) {
      b.SizeTo(0, 0, 0, 0);
    }
#if 0
    if (!spacing->GetPadding(p) && (nsnull != aParentRS))
#else
    spacing->CalcPaddingFor(aFrame, p);
    if ((eStyleUnit_Percent == spacing->mPadding.GetTopUnit()) ||
        (eStyleUnit_Percent == spacing->mPadding.GetRightUnit()) ||
        (eStyleUnit_Percent == spacing->mPadding.GetBottomUnit()) ||
        (eStyleUnit_Percent == spacing->mPadding.GetLeftUnit()))
#endif
    {
      // We have to compute the value (because it's uncomputable by
      // the style code).
      const nsHTMLReflowState* rs = GetContainingBlockReflowState(aParentRS);
      if (nsnull != rs) {
        nsStyleCoord left, right, top, bottom;
        nscoord containingBlockWidth = rs->computedWidth;
        ComputeHorizontalValue(containingBlockWidth, spacing->mPadding.GetLeftUnit(),
                               spacing->mPadding.GetLeft(left), p.left);
        ComputeHorizontalValue(containingBlockWidth, spacing->mPadding.GetRightUnit(),
                               spacing->mPadding.GetRight(right), p.right);

        // According to the CSS2 spec, padding percentages are
        // calculated with respect to the *width* of the containing
        // block, even for padding-top and padding-bottom.
        ComputeHorizontalValue(containingBlockWidth, spacing->mPadding.GetTopUnit(),
                               spacing->mPadding.GetTop(top), p.top);
        ComputeHorizontalValue(containingBlockWidth, spacing->mPadding.GetBottomUnit(),
                               spacing->mPadding.GetBottom(bottom), p.bottom);
      }
      else {
        p.SizeTo(0, 0, 0, 0);
      }
    }

    aResult.top = b.top + p.top;
    aResult.right = b.right + p.right;
    aResult.bottom = b.bottom + p.bottom;
    aResult.left = b.left + p.left;
  }
  else {
    aResult.SizeTo(0, 0, 0, 0);
  }
}

void
nsHTMLReflowState::ComputeMinMaxValues(nscoord aContainingBlockWidth,
                                       nscoord aContainingBlockHeight,
                                       const nsHTMLReflowState* aContainingBlockRS)
{
  nsStyleUnit minWidthUnit = mStylePosition->mMinWidth.GetUnit();
  if (eStyleUnit_Inherit == minWidthUnit) {
    mComputedMinWidth = aContainingBlockRS->mComputedMinWidth;
  } else {
    ComputeHorizontalValue(aContainingBlockWidth, minWidthUnit,
                           mStylePosition->mMinWidth, mComputedMinWidth);
  }
  nsStyleUnit maxWidthUnit = mStylePosition->mMaxWidth.GetUnit();
  if (eStyleUnit_Inherit == maxWidthUnit) {
    mComputedMaxWidth = aContainingBlockRS->mComputedMaxWidth;
  } else {
    ComputeHorizontalValue(aContainingBlockWidth, maxWidthUnit,
                           mStylePosition->mMaxWidth, mComputedMaxWidth);
  }
  nsStyleUnit minHeightUnit = mStylePosition->mMinHeight.GetUnit();
  if (eStyleUnit_Inherit == minHeightUnit) {
    mComputedMinHeight = aContainingBlockRS->mComputedMinHeight;
  } else {
    ComputeVerticalValue(aContainingBlockHeight, minHeightUnit,
                         mStylePosition->mMinHeight, mComputedMinHeight);
  }
  nsStyleUnit maxHeightUnit = mStylePosition->mMaxHeight.GetUnit();
  if (eStyleUnit_Inherit == maxHeightUnit) {
    mComputedMaxHeight = aContainingBlockRS->mComputedMaxHeight;
  } else {
    ComputeVerticalValue(aContainingBlockHeight, maxHeightUnit,
                         mStylePosition->mMaxHeight, mComputedMaxHeight);
  }
}