gecko-dev/layout/tables/nsTableRowGroupFrame.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 "NPL"); you may not use this file except in
 * compliance with the NPL.  You may obtain a copy of the NPL at
 * http://www.mozilla.org/NPL/
 *
 * Software distributed under the NPL is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the NPL
 * for the specific language governing rights and limitations under the
 * NPL.
 *
 * The Initial Developer of this code under the NPL is Netscape
 * Communications Corporation.  Portions created by Netscape are
 * Copyright (C) 1998 Netscape Communications Corporation.  All Rights
 * Reserved.
 */
#include "nsCOMPtr.h"
#include "nsTableRowGroupFrame.h"
#include "nsTableRowFrame.h"
#include "nsTableFrame.h"
#include "nsTableCellFrame.h"
#include "nsIRenderingContext.h"
#include "nsIPresContext.h"
#include "nsIStyleContext.h"
#include "nsStyleConsts.h"
#include "nsIContent.h"
#include "nsIView.h"
#include "nsIPtr.h"
#include "nsIReflowCommand.h"
#include "nsHTMLIIDs.h"
#include "nsIDeviceContext.h"
#include "nsHTMLAtoms.h"
#include "nsIStyleSet.h"
#include "nsIPresShell.h"
#include "nsLayoutAtoms.h"
#include "nsCSSRendering.h"

#ifdef NS_DEBUG
static PRBool gsDebug = PR_FALSE;
static PRBool gsDebugIR = PR_FALSE;
#else
static const PRBool gsDebug = PR_FALSE;
static const PRBool gsDebugIR = PR_FALSE;
#endif

NS_DEF_PTR(nsIStyleContext);
NS_DEF_PTR(nsIContent);

/* ----------- nsTableRowGroupFrame ---------- */

nsresult
nsTableRowGroupFrame::QueryInterface(const nsIID& aIID, void** aInstancePtr)
{
  if (NULL == aInstancePtr) {
    return NS_ERROR_NULL_POINTER;
  }
  static NS_DEFINE_IID(kITableRowGroupIID, NS_ITABLEROWGROUPFRAME_IID);
  if (aIID.Equals(kITableRowGroupIID)) {
    *aInstancePtr = (void*)this;
    return NS_OK;
  } else {
    return nsHTMLContainerFrame::QueryInterface(aIID, aInstancePtr);
  }
}

NS_METHOD nsTableRowGroupFrame::GetRowCount(PRInt32 &aCount, PRBool aDeepCount)
{
  // init out-param
  aCount=0;

  // loop through children, adding one to aCount for every legit row
  nsIFrame *childFrame = GetFirstFrame();
  while (PR_TRUE)
  {
    if (nsnull==childFrame)
      break;
    const nsStyleDisplay *childDisplay;
    childFrame->GetStyleData(eStyleStruct_Display, ((const nsStyleStruct *&)childDisplay));
    if (NS_STYLE_DISPLAY_TABLE_ROW == childDisplay->mDisplay)
      aCount++;
    else if (aDeepCount && NS_STYLE_DISPLAY_TABLE_ROW_GROUP == childDisplay->mDisplay) {
      PRInt32 childRowGroupCount;
      ((nsTableRowGroupFrame*)childFrame)->GetRowCount(childRowGroupCount);
      aCount += childRowGroupCount;
    }
    GetNextFrame(childFrame, &childFrame);
  }
  return NS_OK;
}

PRInt32 nsTableRowGroupFrame::GetStartRowIndex()
{
  PRInt32 result = -1;
  nsIFrame *childFrame = GetFirstFrame();
  while (PR_TRUE)
  {
    if (nsnull==childFrame)
      break;
    const nsStyleDisplay *childDisplay;
    childFrame->GetStyleData(eStyleStruct_Display, ((const nsStyleStruct *&)childDisplay));
    if (NS_STYLE_DISPLAY_TABLE_ROW == childDisplay->mDisplay)
    {
      result = ((nsTableRowFrame *)childFrame)->GetRowIndex();
      break;
    }
    else if (NS_STYLE_DISPLAY_TABLE_ROW_GROUP == childDisplay->mDisplay) {
      result = ((nsTableRowGroupFrame*)childFrame)->GetStartRowIndex();
      if (result != -1)
        break;
    }
    
    GetNextFrame(childFrame, &childFrame);
  }
  return result;
}

NS_METHOD nsTableRowGroupFrame::GetMaxColumns(PRInt32 &aMaxColumns)
{
  aMaxColumns=0;
  // loop through children, remembering the max of the columns in each row
  nsIFrame *childFrame = GetFirstFrame();
  while (PR_TRUE)
  {
    if (nsnull==childFrame)
      break;
    const nsStyleDisplay *childDisplay;
    childFrame->GetStyleData(eStyleStruct_Display, ((const nsStyleStruct *&)childDisplay));
    if (NS_STYLE_DISPLAY_TABLE_ROW == childDisplay->mDisplay)
    {
      PRInt32 colCount = ((nsTableRowFrame *)childFrame)->GetMaxColumns();
      aMaxColumns = PR_MAX(aMaxColumns, colCount);
    }
    else if (NS_STYLE_DISPLAY_TABLE_ROW_GROUP == childDisplay->mDisplay) {
      PRInt32 rgColCount;
      ((nsTableRowGroupFrame*)childFrame)->GetMaxColumns(rgColCount);
      aMaxColumns = PR_MAX(aMaxColumns, rgColCount);
    }

    GetNextFrame(childFrame, &childFrame);
  }
  return NS_OK;
}

nsresult
nsTableRowGroupFrame::InitRepeatedFrame(nsTableRowGroupFrame* aHeaderFooterFrame)
{
  nsIFrame* originalRowFrame;
  nsIFrame* copyRowFrame = GetFirstFrame();

  aHeaderFooterFrame->FirstChild(nsnull, &originalRowFrame);
  while (copyRowFrame) {
    // Set the row frame index
    int rowIndex = ((nsTableRowFrame*)originalRowFrame)->GetRowIndex();
    ((nsTableRowFrame*)copyRowFrame)->SetRowIndex(rowIndex);

    // For each table cell frame set its column index
    nsIFrame* originalCellFrame;
    nsIFrame* copyCellFrame;
    originalRowFrame->FirstChild(nsnull, &originalCellFrame);
    copyRowFrame->FirstChild(nsnull, &copyCellFrame);
    while (copyCellFrame) {
      nsIAtom*  frameType;
      copyCellFrame->GetFrameType(&frameType);

      if (nsLayoutAtoms::tableCellFrame == frameType) {
  #ifdef NS_DEBUG
        nsIContent* content1;
        nsIContent* content2;
        originalCellFrame->GetContent(&content1);
        copyCellFrame->GetContent(&content2);
        NS_ASSERTION(content1 == content2, "cell frames have different content");
        NS_IF_RELEASE(content1);
        NS_IF_RELEASE(content2);
  #endif
        PRInt32 colIndex;
        ((nsTableCellFrame*)originalCellFrame)->GetColIndex(colIndex);
        ((nsTableCellFrame*)copyCellFrame)->InitCellFrame(colIndex);
      }
      NS_IF_RELEASE(frameType);

      // Move to the next cell frame
      copyCellFrame->GetNextSibling(&copyCellFrame);
      originalCellFrame->GetNextSibling(&originalCellFrame);
    }

    // Move to the next row frame
    GetNextFrame(originalRowFrame, &originalRowFrame);
    GetNextFrame(copyRowFrame, &copyRowFrame);
  }

  return NS_OK;
}

NS_METHOD nsTableRowGroupFrame::Paint(nsIPresContext&      aPresContext,
                                      nsIRenderingContext& aRenderingContext,
                                      const nsRect&        aDirtyRect,
                                      nsFramePaintLayer    aWhichLayer)
{
  nsresult rv;
  if (NS_FRAME_PAINT_LAYER_BACKGROUND == aWhichLayer) {
    nsCompatibility mode;
    aPresContext.GetCompatibilityMode(&mode);
    if (eCompatibility_Standard == mode) {
      const nsStyleDisplay* disp =
        (const nsStyleDisplay*)mStyleContext->GetStyleData(eStyleStruct_Display);
      if (disp->mVisible) {
        const nsStyleSpacing* spacing =
          (const nsStyleSpacing*)mStyleContext->GetStyleData(eStyleStruct_Spacing);
        const nsStyleColor* color =
          (const nsStyleColor*)mStyleContext->GetStyleData(eStyleStruct_Color);
        nsTableFrame* tableFrame = nsnull;
        rv = nsTableFrame::GetTableFrame(this, tableFrame);
        if (NS_FAILED(rv) || (nsnull == tableFrame)) {
          return rv;
        }
        nscoord halfCellSpacingY = 
          NSToCoordRound(((float)tableFrame->GetCellSpacingY()) / (float)2);
        // every row group is short by the ending cell spacing X
        nsRect rect(0, 0, mRect.width, mRect.height);
        nsIFrame* firstRowGroup = nsnull;
        tableFrame->FirstChild(nsnull, &firstRowGroup);
        // first row group may have gotten too much cell spacing Y
        if (tableFrame->GetRowCount() != 1) {
          if (this == firstRowGroup) { 
            rect.height -= halfCellSpacingY;
          }
          else {
            rect.height += halfCellSpacingY;
            rect.y      -= halfCellSpacingY;
          }
        }

        nsCSSRendering::PaintBackground(aPresContext, aRenderingContext, this,
                                        aDirtyRect, rect, *color, *spacing, 0, 0);
      }
    }
  }
  // for debug...
  if ((NS_FRAME_PAINT_LAYER_DEBUG == aWhichLayer) && GetShowFrameBorders()) {
    aRenderingContext.SetColor(NS_RGB(0,255,0));
    aRenderingContext.DrawRect(0, 0, mRect.width, mRect.height);
  }

  PaintChildren(aPresContext, aRenderingContext, aDirtyRect, aWhichLayer);
  return nsFrame::Paint(aPresContext, aRenderingContext, aDirtyRect, aWhichLayer);

}

PRIntn
nsTableRowGroupFrame::GetSkipSides() const
{
  PRIntn skip = 0;
  if (nsnull != mPrevInFlow) {
    skip |= 1 << NS_SIDE_TOP;
  }
  if (nsnull != mNextInFlow) {
    skip |= 1 << NS_SIDE_BOTTOM;
  }
  return skip;
}

// aDirtyRect is in our coordinate system
// child rect's are also in our coordinate system
/** overloaded method from nsContainerFrame.  The difference is that 
  * we don't want to clip our children, so a cell can do a rowspan
  */
void nsTableRowGroupFrame::PaintChildren(nsIPresContext&      aPresContext,
                                         nsIRenderingContext& aRenderingContext,
                                         const nsRect&        aDirtyRect,
                                         nsFramePaintLayer    aWhichLayer)
{
  nsIFrame* kid = GetFirstFrame();
  while (nsnull != kid) {
    nsIView *pView;
     
    kid->GetView(&pView);
    if (nsnull == pView) {
      PRBool clipState;
      nsRect kidRect;
      kid->GetRect(kidRect);
      nsRect damageArea(aDirtyRect);
      // Translate damage area into kid's coordinate system
      nsRect kidDamageArea(damageArea.x - kidRect.x, damageArea.y - kidRect.y,
                           damageArea.width, damageArea.height);
      aRenderingContext.PushState();
      aRenderingContext.Translate(kidRect.x, kidRect.y);
      kid->Paint(aPresContext, aRenderingContext, kidDamageArea, aWhichLayer);
      if ((NS_FRAME_PAINT_LAYER_DEBUG == aWhichLayer) &&
          GetShowFrameBorders()) {
        aRenderingContext.SetColor(NS_RGB(255,0,0));
        aRenderingContext.DrawRect(0, 0, kidRect.width, kidRect.height);
      }
      aRenderingContext.PopState(clipState);
    }
    GetNextFrame(kid, &kid);
  }
}

/* we overload this here because rows have children that can span outside of themselves.
 * so the default "get the child rect, see if it contains the event point" action isn't
 * sufficient.  We have to ask the row if it has a child that contains the point.
 */
NS_IMETHODIMP
nsTableRowGroupFrame::GetFrameForPoint(const nsPoint& aPoint, nsIFrame** aFrame)
{
  nsIFrame* kid;
  nsRect kidRect;
  nsPoint tmp;
  *aFrame = this;

  FirstChild(nsnull, &kid);
  while (nsnull != kid) {
    kid->GetRect(kidRect);
    const nsStyleDisplay *childDisplay;
    kid->GetStyleData(eStyleStruct_Display, ((const nsStyleStruct *&)childDisplay));
    if (NS_STYLE_DISPLAY_TABLE_ROW == childDisplay->mDisplay) {
      if (((nsTableRowFrame*)(kid))->Contains(aPoint)) {
        tmp.MoveTo(aPoint.x - kidRect.x, aPoint.y - kidRect.y);
        return kid->GetFrameForPoint(tmp, aFrame);
      }
    }
    else {
      if (kidRect.Contains(aPoint)) {
        tmp.MoveTo(aPoint.x - kidRect.x, aPoint.y - kidRect.y);
        return kid->GetFrameForPoint(tmp, aFrame);
      }
    }

    GetNextFrame(kid, &kid);
  }
  return NS_ERROR_FAILURE;
}

// Position and size aKidFrame and update our reflow state. The origin of
// aKidRect is relative to the upper-left origin of our frame
void nsTableRowGroupFrame::PlaceChild(nsIPresContext&      aPresContext,
																			RowGroupReflowState& aReflowState,
																			nsIFrame*            aKidFrame,
																			const nsRect&        aKidRect,
																			nsSize*              aMaxElementSize,
																			nsSize&              aKidMaxElementSize)
{
  if (PR_TRUE==gsDebug)
    printf ("rowgroup %p: placing row at %d, %d, %d, %d\n",
            this, aKidRect.x, aKidRect.y, aKidRect.width, aKidRect.height);

  // Place and size the child
  aKidFrame->SetRect(aKidRect);

  // Adjust the running y-offset
  aReflowState.y += aKidRect.height;

  // If our height is constrained then update the available height
  if (PR_FALSE == aReflowState.unconstrainedHeight) {
    aReflowState.availSize.height -= aKidRect.height;
  }

  // Update the maximum element size
  if (PR_TRUE==aReflowState.firstRow)
  {
    aReflowState.firstRow = PR_FALSE;
    aReflowState.firstRowHeight = aKidRect.height;
    if (nsnull != aMaxElementSize) {
      aMaxElementSize->width = aKidMaxElementSize.width;
      aMaxElementSize->height = aKidMaxElementSize.height;
    }
  }
  else if (nsnull != aMaxElementSize) {
      aMaxElementSize->width = PR_MAX(aMaxElementSize->width, aKidMaxElementSize.width);
  }
  if (gsDebug && nsnull != aMaxElementSize)
    printf ("rowgroup %p: placing row %p with width = %d and MES= %d\n",
            this, aKidFrame, aKidRect.width, aMaxElementSize->width);
}

/**
 * Reflow the frames we've already created
 *
 * @param   aPresContext presentation context to use
 * @param   aReflowState current inline state
 * @return  true if we successfully reflowed all the mapped children and false
 *            otherwise, e.g. we pushed children to the next in flow
 */
NS_METHOD nsTableRowGroupFrame::ReflowMappedChildren(nsIPresContext&      aPresContext,
                                                     nsHTMLReflowMetrics& aDesiredSize,
                                                     RowGroupReflowState& aReflowState,
                                                     nsReflowStatus&      aStatus,
                                                     nsTableRowFrame *    aStartFrame,
                                                     nsReflowReason       aReason,
                                                     PRBool               aDoSiblings)
{
  if (PR_TRUE==gsDebugIR) printf("\nTRGF IR: ReflowMappedChildren\n");
  nsSize    kidMaxElementSize;
  nsSize*   pKidMaxElementSize = (nsnull != aDesiredSize.maxElementSize) ? &kidMaxElementSize : nsnull;
  nsresult  rv = NS_OK;

  if (!ContinueReflow(aPresContext, aReflowState.y, aReflowState.availSize.height))
      return rv;

  nsIFrame*  kidFrame;
  if (nsnull==aStartFrame) {
    kidFrame = GetFirstFrameForReflow(aPresContext);
    ReflowBeforeRowLayout(aPresContext, aDesiredSize, aReflowState, aStatus, aReason);
  }
  else
    kidFrame = aStartFrame;
                   
  PRUint8 borderStyle = aReflowState.tableFrame->GetBorderCollapseStyle();
 
  for ( ; nsnull != kidFrame; ) 
  {
    nsSize kidAvailSize(aReflowState.availSize);
    if (0>=kidAvailSize.height)
      kidAvailSize.height = 1;      // XXX: HaCk - we don't handle negative heights yet
    nsHTMLReflowMetrics desiredSize(pKidMaxElementSize);
    desiredSize.width=desiredSize.height=desiredSize.ascent=desiredSize.descent=0;

    // Reflow the child into the available space, giving it as much room as
    // it wants. We'll deal with splitting later after we've computed the row
    // heights, taking into account cells with row spans...
    kidAvailSize.height = NS_UNCONSTRAINEDSIZE;
    nsHTMLReflowState kidReflowState(aPresContext, aReflowState.reflowState, kidFrame,
                                     kidAvailSize, aReason);
   
    if (aReflowState.tableFrame->RowGroupsShouldBeConstrained()) {
      // Only applies to the tree widget.
      const nsStyleDisplay *rowDisplay;
      kidFrame->GetStyleData(eStyleStruct_Display, ((const nsStyleStruct *&)rowDisplay));
      if (NS_STYLE_DISPLAY_TABLE_ROW_GROUP == rowDisplay->mDisplay &&
          aReflowState.availSize.height != NS_UNCONSTRAINEDSIZE) {
        kidReflowState.availableHeight = aReflowState.availSize.height;
      }
    }

    if (kidFrame != GetFirstFrame()) {
      // If this isn't the first row frame, then we can't be at the top of
      // the page anymore...
      kidReflowState.isTopOfPage = PR_FALSE;
    }

    if ((PR_TRUE==gsDebug) || (PR_TRUE==gsDebugIR))
      printf("%p RG reflowing child %p with avail width = %d, reason = %d\n",
                        this, kidFrame, kidAvailSize.width, aReason);
    rv = ReflowChild(kidFrame, aPresContext, desiredSize, kidReflowState, aStatus);
    if (gsDebug) printf("%p RG child %p returned desired width = %d\n",
                        this, kidFrame, desiredSize.width);

    nsRect kidRect (0, aReflowState.y, desiredSize.width, desiredSize.height);
    PlaceChild(aPresContext, aReflowState, kidFrame, kidRect, aDesiredSize.maxElementSize,
               kidMaxElementSize);

    /* if the table has collapsing borders, we need to reset the length of the shared vertical borders
     * for the table and the cells that overlap this row
     */
    if ((eReflowReason_Initial != aReflowState.reflowState.reason) && (NS_STYLE_BORDER_COLLAPSE==borderStyle))
    {
      const nsStyleDisplay *childDisplay;
      kidFrame->GetStyleData(eStyleStruct_Display, ((const nsStyleStruct *&)childDisplay));
      if (NS_STYLE_DISPLAY_TABLE_ROW == childDisplay->mDisplay)
      {
        PRInt32 rowIndex = ((nsTableRowFrame*)kidFrame)->GetRowIndex();
        aReflowState.tableFrame->SetBorderEdgeLength(NS_SIDE_LEFT,
                                                     rowIndex,
                                                     kidRect.height);
        aReflowState.tableFrame->SetBorderEdgeLength(NS_SIDE_RIGHT,
                                                     rowIndex,
                                                     kidRect.height);
        PRInt32 colCount = aReflowState.tableFrame->GetColCount();
        PRInt32 colIndex = 0;
        nsIFrame *cellFrame;
        for (colIndex = 0; colIndex < colCount; colIndex++) {
          cellFrame = aReflowState.tableFrame->GetCellFrameAt(rowIndex, colIndex);
          if (cellFrame) {
            const nsStyleDisplay *cellDisplay;
            cellFrame->GetStyleData(eStyleStruct_Display, ((const nsStyleStruct *&)cellDisplay));
            if (NS_STYLE_DISPLAY_TABLE_CELL == cellDisplay->mDisplay) {
              ((nsTableCellFrame *)(cellFrame))->SetBorderEdgeLength(NS_SIDE_LEFT,
                                                                     rowIndex,
                                                                     kidRect.height);
              ((nsTableCellFrame *)(cellFrame))->SetBorderEdgeLength(NS_SIDE_RIGHT,
                                                                     rowIndex,
                                                                     kidRect.height);
            }
          }
        }
      }
    }

    if (PR_FALSE==aDoSiblings)
      break;

    if (!ContinueReflow(aPresContext, aReflowState.y, aReflowState.availSize.height))
      break;

    // Get the next child
    GetNextFrameForReflow(aPresContext, kidFrame, &kidFrame);
  }

  // Call our post-row reflow hook
  ReflowAfterRowLayout(aPresContext, aDesiredSize, aReflowState, aStatus, aReason);
  return rv;
}

/**
 * Pull-up all the row frames from our next-in-flow
 */
NS_METHOD nsTableRowGroupFrame::PullUpAllRowFrames(nsIPresContext& aPresContext)
{
  if (mNextInFlow) {
    nsTableRowGroupFrame* nextInFlow = (nsTableRowGroupFrame*)mNextInFlow;
  
    while (nsnull != nextInFlow) {
      // Any frames on the next-in-flow's overflow list?
      if (nextInFlow->mOverflowFrames.NotEmpty()) {
        // Yes, append them to its child list
        nextInFlow->mFrames.AppendFrames(nextInFlow, nextInFlow->mOverflowFrames);
      }

      // Any row frames?
      if (nextInFlow->mFrames.NotEmpty()) {
        // When pushing and pulling frames we need to check for whether any
        // views need to be reparented.
        for (nsIFrame* f = nextInFlow->GetFirstFrame(); f; GetNextFrame(f, &f)) {
          nsHTMLContainerFrame::ReparentFrameView(f, nextInFlow, this);
        }
        // Append them to our child list
        mFrames.AppendFrames(this, nextInFlow->mFrames);
      }

      // Move to the next-in-flow        
      nextInFlow->GetNextInFlow((nsIFrame**)&nextInFlow);
    }
  }

  return NS_OK;
}

void nsTableRowGroupFrame::GetNextRowSibling(nsIFrame** aRowFrame)
{
  GetNextFrame(*aRowFrame, aRowFrame);
  while(*aRowFrame) {
    const nsStyleDisplay *display;
    (*aRowFrame)->GetStyleData(eStyleStruct_Display, ((const nsStyleStruct *&)display));
    if (NS_STYLE_DISPLAY_TABLE_ROW == display->mDisplay) {
      return;
    }
    GetNextFrame(*aRowFrame, aRowFrame);
  }
}

/* CalculateRowHeights provides default heights for all rows in the rowgroup.
 * Actual row heights are ultimately determined by the table, when the table
 * height attribute is factored in.
 */
void nsTableRowGroupFrame::CalculateRowHeights(nsIPresContext& aPresContext, 
                                               nsHTMLReflowMetrics& aDesiredSize,
                                               const nsHTMLReflowState& aReflowState)
{
  if (gsDebug) printf("TRGF CalculateRowHeights begin\n");
  nsTableFrame *tableFrame=nsnull;
  nsresult rv = nsTableFrame::GetTableFrame(this, tableFrame);
  if (NS_FAILED(rv) || nsnull==tableFrame)
    return;
  // all table cells have the same top and bottom margins, namely cellSpacingY
  nscoord cellSpacingY = tableFrame->GetCellSpacingY();

  // iterate children and for each row get its height
  PRInt32 numRows;
  GetRowCount(numRows, PR_FALSE);
  PRInt32 *rowHeights = new PRInt32[numRows];
  nsCRT::memset (rowHeights, 0, numRows*sizeof(PRInt32));

  /* Step 1:  get the height of the tallest cell in the row and save it for
   *          pass 2
   */
  nsIFrame* rowFrame = GetFirstFrame();
  PRInt32 rowIndex = 0;

  // For row groups that are split across pages, the first row frame won't
  // necessarily be index 0
  PRInt32 startRowIndex = -1;
  const nsStyleDisplay *childDisplay;
  while (nsnull != rowFrame)
  {
    rowFrame->GetStyleData(eStyleStruct_Display, ((const nsStyleStruct *&)childDisplay));
    if (NS_STYLE_DISPLAY_TABLE_ROW == childDisplay->mDisplay)
    {
      if (startRowIndex == -1) {
        startRowIndex = ((nsTableRowFrame*)rowFrame)->GetRowIndex();
      }

      // get the height of the tallest cell in the row (excluding cells that span rows)
      // XXX GetChildMaxTopMargin and GetChildMaxBottomMargin should be removed/simplified because
      // according to CSS, all table cells must have the same top/bottom and left/right margins.
      nscoord maxCellHeight       = ((nsTableRowFrame*)rowFrame)->GetTallestChild();
      nscoord maxCellTopMargin    = ((nsTableRowFrame*)rowFrame)->GetChildMaxTopMargin();
      nscoord maxCellBottomMargin = ((nsTableRowFrame*)rowFrame)->GetChildMaxBottomMargin();
      nscoord maxRowHeight = maxCellHeight + maxCellTopMargin + maxCellBottomMargin;
      // only the top row has a top margin. Other rows start at the bottom of the prev row's bottom margin.
      if (gsDebug) printf("TRGF CalcRowH: for row %d(%p), maxCellH=%d, spacingY=%d, d\n",
                            rowIndex + startRowIndex, rowFrame, maxCellHeight, cellSpacingY);
      if (gsDebug) printf("  rowHeight=%d\n", maxRowHeight);

      // save the row height for pass 2 below
      rowHeights[rowIndex] = maxRowHeight;
      rowIndex++;
    }
    // Get the next row
    GetNextFrame(rowFrame, &rowFrame);
  }
  

  /* Step 2:  Now account for cells that span rows.
   *          A spanning cell's height is the sum of the heights of the rows it spans,
   *          or it's own desired height, whichever is greater.
   *          If the cell's desired height is the larger value, resize the rows and contained
   *          cells by an equal percentage of the additional space.
   *          We go through this loop twice.  The first time, we are adjusting cell heights
   *          and row y-offsets on the fly.
   *          The second time through the loop, we're ensuring that subsequent row-spanning cells
   *          didn't change prior calculations.  
   *          Since we are guaranteed to have found the max height spanners the first time through, 
   *          we know we only need two passes, not an arbitrary number.
   */
  /* TODO
   * 1. optimization, if (PR_TRUE==atLeastOneRowSpanningCell) ... otherwise skip this step entirely
   *    we can get this info trivially from the cell map
   */

  PRInt32 rowGroupHeight;
  for (PRInt32 counter=0; counter<2; counter++)
  {
    rowGroupHeight = 0;
    rowFrame = GetFirstFrame();
    rowIndex = 0;
    while (nsnull != rowFrame)
    {
      rowFrame->GetStyleData(eStyleStruct_Display, ((const nsStyleStruct *&)childDisplay));
      if (NS_STYLE_DISPLAY_TABLE_ROW == childDisplay->mDisplay)
      {
        if (gsDebug) printf("TRGF CalcRowH: Step 2 for row %d (%p)...\n",
                            rowIndex + startRowIndex, rowFrame);
        // check this row for a cell with rowspans
        nsIFrame *cellFrame;
        rowFrame->FirstChild(nsnull, &cellFrame);
        while (nsnull != cellFrame)
        {
          const nsStyleDisplay *cellChildDisplay;
          cellFrame->GetStyleData(eStyleStruct_Display, ((const nsStyleStruct *&)cellChildDisplay));
          if (NS_STYLE_DISPLAY_TABLE_CELL == cellChildDisplay->mDisplay)
          {
            if (gsDebug) printf("TRGF CalcRowH:   for cell %p...\n", cellFrame);
            PRInt32 rowSpan = tableFrame->GetEffectiveRowSpan(rowIndex + startRowIndex,
                                                              (nsTableCellFrame*)cellFrame);
            if (rowSpan > 1)
            { // found a cell with rowspan > 1, determine its height
              if (gsDebug) printf("TRGF CalcRowH:   cell %p has rowspan=%d\n", cellFrame, rowSpan);
              nscoord heightOfRowsSpanned = 0;
              PRInt32 i;
              for (i = 0; i < rowSpan; i++) {
                heightOfRowsSpanned += rowHeights[rowIndex + i];
              }
              // the avail height needs to reduce by top and bottom margins
              nscoord availHeightOfRowsSpanned = heightOfRowsSpanned - cellSpacingY - cellSpacingY;
              if (gsDebug) printf("TRGF CalcRowH:   availHeightOfRowsSpanned=%d\n", availHeightOfRowsSpanned);
              /* if the cell height fits in the rows, expand the spanning cell's height and slap it in */
              nsSize  cellFrameSize;
              cellFrame->GetSize(cellFrameSize);
              if (availHeightOfRowsSpanned > cellFrameSize.height)
              {
                if (gsDebug) printf("TRGF CalcRowH:   spanning cell fits in rows spanned, had h=%d, expanded to %d\n", 
                                    cellFrameSize.height, availHeightOfRowsSpanned);
                cellFrame->SizeTo(cellFrameSize.width, availHeightOfRowsSpanned);
                // Realign cell content based on new height
                ((nsTableCellFrame*)cellFrame)->VerticallyAlignChild();
              }
              /* otherwise, distribute the excess height to the rows effected.
               * push all subsequent rows down by the total change in height of all the rows above it
               */
              else
              {
                PRInt32 excessHeight = cellFrameSize.height - availHeightOfRowsSpanned;
                if (gsDebug) printf("TRGF CalcRowH:   excessHeight=%d\n", excessHeight);
                // for every row starting at the row with the spanning cell...
                nsTableRowFrame *rowFrameToBeResized = (nsTableRowFrame *)rowFrame;
                PRInt32 *excessForRow = new PRInt32[numRows];
                nsCRT::memset (excessForRow, 0, numRows*sizeof(PRInt32));
                nscoord excessAllocated = 0;
                for (i = rowIndex; i < numRows; i++) {
                  if (gsDebug) printf("TRGF CalcRowH:     for row index=%d\n", i);
                  // if the row is within the spanned range, resize the row
                  if (i < (rowIndex + rowSpan)) {
                    //float percent = ((float)rowHeights[i]) / ((float)availHeightOfRowsSpanned);
                    //excessForRow[i] = NSToCoordRound(((float)(excessHeight)) * percent); 
                    float percent = ((float)rowHeights[i]) / ((float)heightOfRowsSpanned);
                    // give rows their percentage, except the last row gets the remainder
                    excessForRow[i] = ((i - 1) == (rowIndex + rowSpan))
                      ? excessHeight - excessAllocated 
                      : NSToCoordRound(((float)(excessHeight)) * percent);
                    excessAllocated += excessForRow[i];
                    if (gsDebug) printf("TRGF CalcRowH:   for row %d, excessHeight=%d from percent %f\n", 
                                        i, excessForRow[i], percent);
                    // update the row height
                    rowHeights[i] += excessForRow[i];

                    // adjust the height of the row
                    nsSize  rowFrameSize;
                    rowFrameToBeResized->GetSize(rowFrameSize);
                    rowFrameToBeResized->SizeTo(rowFrameSize.width, rowHeights[i]);
                    if (gsDebug) printf("TRGF CalcRowH:     row %d (%p) sized to %d\n", 
                                        i, rowFrameToBeResized, rowHeights[i]);
                  }

                  // if we're dealing with a row below the row containing the spanning cell, 
                  // push that row down by the amount we've expanded the cell heights by
                  if ((i >= rowIndex) && (i != 0))
                  {
                    nsRect rowRect;
               
                    rowFrameToBeResized->GetRect(rowRect);
                    nscoord delta=0;
                    for (PRInt32 j=0; j<i; j++)
                      delta += excessForRow[j];
                    if (delta > excessHeight)
                      delta = excessHeight;
                    rowFrameToBeResized->MoveTo(rowRect.x, rowRect.y + delta);
                    if (gsDebug) printf("TRGF CalcRowH:     row %d (%p) moved to %d after delta %d\n", 
                                         i, rowFrameToBeResized, rowRect.y + delta, delta);
                  }
                  // Get the next row frame
                  GetNextRowSibling((nsIFrame**)&rowFrameToBeResized);
                }
                delete []excessForRow;
              }
            }
          }
          // Get the next row child (cell frame)
          cellFrame->GetNextSibling(&cellFrame);
        }
        // Update the running row group height
        rowGroupHeight += rowHeights[rowIndex];
        rowIndex++;
      }
      else {
        // Anything that isn't a row contributes to the row group's total height.
        nsSize frameSize;
        rowFrame->GetSize(frameSize);
        rowGroupHeight += frameSize.height;
      }
      
      // Get the next rowgroup child (row frame)
      GetNextFrame(rowFrame, &rowFrame);
    }
  }

  /* step 3: finally, notify the rows of their new heights */
  rowFrame = GetFirstFrame();
  while (nsnull != rowFrame)
  {
    rowFrame->GetStyleData(eStyleStruct_Display, ((const nsStyleStruct *&)childDisplay));
    if (NS_STYLE_DISPLAY_TABLE_ROW == childDisplay->mDisplay)
    {
      ((nsTableRowFrame *)rowFrame)->DidResize(aPresContext, aReflowState);
    }
    // Get the next row
    GetNextFrame(rowFrame, &rowFrame);
  }

  // Adjust our desired size
  aDesiredSize.height = rowGroupHeight;

  // cleanup
  delete []rowHeights;
}

nsresult nsTableRowGroupFrame::AdjustSiblingsAfterReflow(nsIPresContext&      aPresContext,
                                                         RowGroupReflowState& aReflowState,
                                                         nsIFrame*            aKidFrame,
                                                         nscoord              aDeltaY)
{
  if (PR_TRUE==gsDebugIR) printf("\nTRGF IR: AdjustSiblingsAfterReflow\n");
  nsIFrame* lastKidFrame = aKidFrame;

  if (aDeltaY != 0) {
    // Move the frames that follow aKidFrame by aDeltaY
    nsIFrame* kidFrame;

    GetNextFrame(aKidFrame, &kidFrame);

    while (nsnull != kidFrame) {
      nsPoint origin;
  
      // XXX We can't just slide the child if it has a next-in-flow
      kidFrame->GetOrigin(origin);
      origin.y += aDeltaY;
  
      // XXX We need to send move notifications to the frame...
      nsIHTMLReflow* htmlReflow;
      if (NS_OK == kidFrame->QueryInterface(kIHTMLReflowIID, (void**)&htmlReflow)) {
        htmlReflow->WillReflow(aPresContext);
      }
      kidFrame->MoveTo(origin.x, origin.y);

      // Get the next frame
      lastKidFrame = kidFrame;
      GetNextFrame(kidFrame, &kidFrame);
    }

  } else {
    // Get the last frame
    lastKidFrame = GetLastFrame();
  }

  // XXX Deal with cells that have rowspans.

  // Update our running y-offset to reflect the bottommost child
  nsRect  rect;
  lastKidFrame->GetRect(rect);
  aReflowState.y = rect.YMost();

  return NS_OK;
}

nsresult
nsTableRowGroupFrame::SplitRowGroup(nsIPresContext&          aPresContext,
                                    nsHTMLReflowMetrics&     aDesiredSize,
                                    const nsHTMLReflowState& aReflowState,
                                    nsTableFrame*            aTableFrame,
                                    nsReflowStatus&          aStatus)
{
  nsIFrame* prevRowFrame = nsnull;
  nsresult  rv = NS_OK;

  // Walk each of the row frames looking for the first row frame that
  // doesn't fit in the available space
  for (nsIFrame* rowFrame = GetFirstFrame(); rowFrame; GetNextFrame(rowFrame, &rowFrame)) {
    nsRect  bounds;

    rowFrame->GetRect(bounds);
    if (bounds.YMost() > aReflowState.availableHeight) {
      // If this is the first row frame then we need to split it
      if (!prevRowFrame) {
        // Reflow the row in the available space and have it split
        nsSize              availSize(aReflowState.availableWidth,
                                      aReflowState.availableHeight - bounds.y);
        nsHTMLReflowState   rowReflowState(aPresContext, aReflowState, rowFrame,
                                          availSize, eReflowReason_Resize);
        nsHTMLReflowMetrics desiredSize(nsnull);

        rv = ReflowChild(rowFrame, aPresContext, desiredSize, rowReflowState, aStatus);
        rowFrame->SizeTo(desiredSize.width, desiredSize.height);
        ((nsTableRowFrame *)rowFrame)->DidResize(aPresContext, aReflowState);
        aDesiredSize.height = desiredSize.height;

        if (NS_FRAME_IS_NOT_COMPLETE(aStatus)) {
#ifdef NS_DEBUG
          // Verify it doesn't already have a next-in-flow. The reason it should
          // not already have a next-in-flow is that ReflowMappedChildren() reflows
          // the row frames with an unconstrained available height
          nsIFrame* nextInFlow;
          rowFrame->GetNextInFlow(&nextInFlow);
          NS_ASSERTION(!nextInFlow, "row frame already has next-in-flow");
#endif
          // Create a continuing frame, add it to the child list, and then push it
          // and the frames that follow
          nsIFrame*        contRowFrame;
          nsIPresShell*    presShell;
          nsIStyleSet*     styleSet;
          
          aPresContext.GetShell(&presShell);
          presShell->GetStyleSet(&styleSet);
          NS_RELEASE(presShell);
          styleSet->CreateContinuingFrame(&aPresContext, rowFrame, this, &contRowFrame);
          NS_RELEASE(styleSet);
  
          // Add it to the child list
          nsIFrame* nextRow;
          GetNextFrame(rowFrame, &nextRow);
          GetNextFrame(contRowFrame, &nextRow);
          GetNextFrame(rowFrame, &contRowFrame);
          
          // Push the continuing row frame and the frames that follow
          PushChildren(contRowFrame, rowFrame);
          aStatus = NS_FRAME_NOT_COMPLETE;

        } else {
          // The row frame is complete. It may be the case that it's minimum
          // height was greater than the available height we gave it
          nsIFrame* nextRowFrame;

          // Push the frame that follows
          GetNextFrame(rowFrame, &nextRowFrame);
          
          if (nextRowFrame) {
            PushChildren(nextRowFrame, rowFrame);
          }
          aStatus = nextRowFrame ? NS_FRAME_NOT_COMPLETE : NS_FRAME_COMPLETE;
        }

      } else {
        // See whether the row frame has cells that span into it
        PRInt32           rowIndex = ((nsTableRowFrame*)rowFrame)->GetRowIndex();
        PRInt32           colCount = aTableFrame->GetColCount();
        nsTableCellFrame* prevCellFrame = nsnull;

        for (PRInt32 colIndex = 0; colIndex < colCount; colIndex++) {
          nsTableCellFrame* cellFrame = aTableFrame->GetCellFrameAt(rowIndex, colIndex);
          NS_ASSERTION(cellFrame, "no cell frame");

          // See if the cell frame is really in this row, or whether it's a
          // row span from a previous row
          PRInt32 realRowIndex;
          cellFrame->GetRowIndex(realRowIndex);
          if (realRowIndex == rowIndex) {
            prevCellFrame = cellFrame;
          } else {
            // This cell frame spans into the row we're pushing, so we need to:
            // - reflow the cell frame into the new smaller space
            // - create a continuing frame for the cell frame (we do this regardless
            //   of whether it's complete)
            // - add the continuing frame to the row frame we're pushing
            nsIFrame*         parentFrame;
            nsPoint           firstRowOrigin, lastRowOrigin;
            nsReflowStatus    status;

            // Ask the cell frame's parent to reflow it to the height of all the
            // rows it spans between its parent frame and the row we're pushing
            cellFrame->GetParent(&parentFrame);
            parentFrame->GetOrigin(firstRowOrigin);
            rowFrame->GetOrigin(lastRowOrigin);
            ((nsTableRowFrame*)parentFrame)->ReflowCellFrame(aPresContext,
              aReflowState, cellFrame, lastRowOrigin.y - firstRowOrigin.y, status);
            
            // Create the continuing cell frame
            nsIFrame*         contCellFrame;
            nsIPresShell*     presShell;
            nsIStyleSet*      styleSet;

            aPresContext.GetShell(&presShell);
            presShell->GetStyleSet(&styleSet);
            NS_RELEASE(presShell);
            styleSet->CreateContinuingFrame(&aPresContext, cellFrame, rowFrame, &contCellFrame);
            NS_RELEASE(styleSet);

            // Add it to the row's child list
            ((nsTableRowFrame*)rowFrame)->InsertCellFrame((nsTableCellFrame*)contCellFrame,
                                                          prevCellFrame);
            prevCellFrame = (nsTableCellFrame*)contCellFrame;
          }
        }

        // Push this row frame and those that follow to the next-in-flow
        PushChildren(rowFrame, prevRowFrame);
        aStatus = NS_FRAME_NOT_COMPLETE;
        aDesiredSize.height = bounds.y;
      }

      break;
    }

    prevRowFrame = rowFrame;
  }

  return NS_OK;
}

/** Layout the entire row group.
  * This method stacks rows vertically according to HTML 4.0 rules.
  * Rows are responsible for layout of their children.
  */
NS_METHOD
nsTableRowGroupFrame::Reflow(nsIPresContext&          aPresContext,
                             nsHTMLReflowMetrics&     aDesiredSize,
                             const nsHTMLReflowState& aReflowState,
                             nsReflowStatus&          aStatus)
{
  nsresult rv=NS_OK;
  if (gsDebug==PR_TRUE)
    printf("nsTableRowGroupFrame::Reflow - aMaxSize = %d, %d\n",
            aReflowState.availableWidth, aReflowState.availableHeight);

  // Initialize out parameter
  if (nsnull != aDesiredSize.maxElementSize) {
    aDesiredSize.maxElementSize->width = 0;
    aDesiredSize.maxElementSize->height = 0;
  }

  nsTableFrame *tableFrame=nsnull;
  rv = nsTableFrame::GetTableFrame(this, tableFrame);
  if (NS_FAILED(rv))
    return rv;
  else if (tableFrame == nsnull)
    return NS_ERROR_NULL_POINTER;

  RowGroupReflowState state(aPresContext, aReflowState, tableFrame);

  if (eReflowReason_Incremental == aReflowState.reason) {
    rv = IncrementalReflow(aPresContext, aDesiredSize, state, aStatus);
  } else {
    aStatus = NS_FRAME_COMPLETE;
  
    // Check for an overflow list
    MoveOverflowToChildList();
  
    // Reflow the existing frames. Before we do, pull-up any row frames from
    // our next-in-flow.
    // XXX It would be more efficient to do this if we have room left after
    // reflowing the frames we have, the problem is we don't know if we have
    // room left until after we call CalculateRowHeights()...
    PullUpAllRowFrames(aPresContext);
    rv = ReflowMappedChildren(aPresContext, aDesiredSize, state, aStatus,
                                nsnull, aReflowState.reason, PR_TRUE);
  
    // Return our desired rect
    aDesiredSize.width = aReflowState.availableWidth;
    aDesiredSize.height = state.y;

    // account for scroll bars. XXX needs optimization/caching
    if (nsnull != aDesiredSize.maxElementSize) {
      nsIAtom* pseudoTag;
 
      mStyleContext->GetPseudoType(pseudoTag);
      if (pseudoTag == nsHTMLAtoms::scrolledContentPseudo) {
        nsIFrame* scrollFrame;
        GetParent(&scrollFrame);
        const nsStyleDisplay *display;
        scrollFrame->GetStyleData(eStyleStruct_Display, ((const nsStyleStruct *&)display));
        if ((NS_STYLE_OVERFLOW_SCROLL == display->mOverflow) ||
            (NS_STYLE_OVERFLOW_AUTO   == display->mOverflow)) {
          float sbWidth, sbHeight;
          nsCOMPtr<nsIDeviceContext> dc;
          aPresContext.GetDeviceContext(getter_AddRefs(dc));

          dc->GetScrollBarDimensions(sbWidth, sbHeight);
          aDesiredSize.maxElementSize->width += NSToCoordRound(sbWidth);
          // If scrollbars are always visible then add in the hor sb height 
          if (NS_STYLE_OVERFLOW_SCROLL == display->mOverflow) {
            aDesiredSize.maxElementSize->height += NSToCoordRound(sbHeight);
          }
        }
      }
      NS_IF_RELEASE(pseudoTag);
    }

    // shrink wrap rows to height of tallest cell in that row
    if (eReflowReason_Initial != aReflowState.reason) {
      CalculateRowHeights(aPresContext, aDesiredSize, aReflowState);
    }

    // See if all the frames fit
    if (aDesiredSize.height > aReflowState.availableHeight && 
        !tableFrame->RowGroupsShouldBeConstrained()) {
      // Nope, find a place to split the row group
      SplitRowGroup(aPresContext, aDesiredSize, aReflowState, tableFrame, aStatus);
    }
  }

  if (gsDebug==PR_TRUE) 
  {
    if (nsnull!=aDesiredSize.maxElementSize)
      printf("nsTableRowGroupFrame %p returning: %s with aDesiredSize=%d,%d, aMES=%d,%d\n",
              this, NS_FRAME_IS_COMPLETE(aStatus)?"Complete":"Not Complete",
              aDesiredSize.width, aDesiredSize.height,
              aDesiredSize.maxElementSize->width, aDesiredSize.maxElementSize->height);
    else
      printf("nsTableRowGroupFrame %p returning: %s with aDesiredSize=%d,%d, aMES=NSNULL\n", 
             this, NS_FRAME_IS_COMPLETE(aStatus)?"Complete":"Not Complete",
             aDesiredSize.width, aDesiredSize.height);
  }
  return rv;
}


NS_METHOD nsTableRowGroupFrame::IncrementalReflow(nsIPresContext& aPresContext,
                                                  nsHTMLReflowMetrics& aDesiredSize,
                                                  RowGroupReflowState& aReflowState,
                                                  nsReflowStatus& aStatus)
{
  if (PR_TRUE==gsDebugIR) printf("\nTRGF IR: IncrementalReflow\n");
  nsresult  rv = NS_OK;

  // determine if this frame is the target or not
  nsIFrame *target=nsnull;
  rv = aReflowState.reflowState.reflowCommand->GetTarget(target);
  if ((PR_TRUE==NS_SUCCEEDED(rv)) && (nsnull!=target))
  {
    if (this==target)
      rv = IR_TargetIsMe(aPresContext, aDesiredSize, aReflowState, aStatus);
    else
    {
      // Get the next frame in the reflow chain
      nsIFrame* nextFrame;
      aReflowState.reflowState.reflowCommand->GetNext(nextFrame);

      // Recover our reflow state
      //RecoverState(state, nextFrame);
      rv = IR_TargetIsChild(aPresContext, aDesiredSize, aReflowState, aStatus, nextFrame);
    }
  }
  return rv;
}

NS_METHOD nsTableRowGroupFrame::IR_TargetIsMe(nsIPresContext&      aPresContext,
                                              nsHTMLReflowMetrics& aDesiredSize,
                                              RowGroupReflowState& aReflowState,
                                              nsReflowStatus&      aStatus)
{
  nsresult rv = NS_FRAME_COMPLETE;
  nsIReflowCommand::ReflowType type;
  aReflowState.reflowState.reflowCommand->GetType(type);
  nsIFrame *objectFrame;
  aReflowState.reflowState.reflowCommand->GetChildFrame(objectFrame); 
  const nsStyleDisplay *childDisplay=nsnull;
  if (nsnull!=objectFrame)
    objectFrame->GetStyleData(eStyleStruct_Display, ((const nsStyleStruct *&)childDisplay));
  if (PR_TRUE==gsDebugIR) printf("TRGF IR: TargetIsMe with type=%d\n", type);
  switch (type)
  {
  case nsIReflowCommand::FrameInserted :
    NS_ASSERTION(nsnull!=objectFrame, "bad objectFrame");
    NS_ASSERTION(nsnull!=childDisplay, "bad childDisplay");
    if (NS_STYLE_DISPLAY_TABLE_ROW == childDisplay->mDisplay)
    {
      rv = IR_RowInserted(aPresContext, aDesiredSize, aReflowState, aStatus, 
                          (nsTableRowFrame *)objectFrame, PR_FALSE);
    }
    else if (NS_STYLE_DISPLAY_TABLE_ROW_GROUP == childDisplay->mDisplay)
    {
      rv = IR_RowGroupInserted(aPresContext, aDesiredSize, aReflowState, aStatus,
                               (nsTableRowGroupFrame*)objectFrame, PR_FALSE);
    }
    else
    {
      rv = AddFrame(aReflowState.reflowState, objectFrame);
    }
    break;
  
  case nsIReflowCommand::FrameAppended :
    NS_ASSERTION(nsnull!=objectFrame, "bad objectFrame");
    NS_ASSERTION(nsnull!=childDisplay, "bad childDisplay");
    if (NS_STYLE_DISPLAY_TABLE_ROW == childDisplay->mDisplay)
    {
      rv = IR_RowAppended(aPresContext, aDesiredSize, aReflowState, aStatus, 
                          (nsTableRowFrame *)objectFrame);
    }
    else if (NS_STYLE_DISPLAY_TABLE_ROW_GROUP == childDisplay->mDisplay)
    {
      rv = IR_RowGroupInserted(aPresContext, aDesiredSize, aReflowState, aStatus,
                               (nsTableRowGroupFrame*)objectFrame, PR_FALSE);
    }
    else
    { // no optimization to be done for Unknown frame types, so just reuse the Inserted method
      rv = AddFrame(aReflowState.reflowState, objectFrame);
    }
    break;

  /*
  case nsIReflowCommand::FrameReplaced :

  */

  case nsIReflowCommand::FrameRemoved :
    NS_ASSERTION(nsnull!=objectFrame, "bad objectFrame");
    NS_ASSERTION(nsnull!=childDisplay, "bad childDisplay");
    if (NS_STYLE_DISPLAY_TABLE_ROW == childDisplay->mDisplay)
    {
      rv = IR_RowRemoved(aPresContext, aDesiredSize, aReflowState, aStatus, 
                         (nsTableRowFrame *)objectFrame);
    }
    else if (NS_STYLE_DISPLAY_TABLE_ROW_GROUP == childDisplay->mDisplay)
    {
      rv = IR_RowGroupRemoved(aPresContext, aDesiredSize, aReflowState, aStatus, 
                             (nsTableRowGroupFrame *)objectFrame);
    }
    else
    {
      rv = mFrames.DestroyFrame(aPresContext, objectFrame);
    }
    break;

  case nsIReflowCommand::StyleChanged :
    rv = IR_StyleChanged(aPresContext, aDesiredSize, aReflowState, aStatus);
    break;

  case nsIReflowCommand::ContentChanged :
    NS_ASSERTION(PR_FALSE, "illegal reflow type: ContentChanged");
    rv = NS_ERROR_ILLEGAL_VALUE;
    break;
  
  case nsIReflowCommand::PullupReflow:
  case nsIReflowCommand::PushReflow:
  case nsIReflowCommand::CheckPullupReflow :
  case nsIReflowCommand::UserDefined :
  default:
    NS_NOTYETIMPLEMENTED("unimplemented reflow command type");
    rv = NS_ERROR_NOT_IMPLEMENTED;
    if (PR_TRUE==gsDebugIR) printf("TRGF IR: reflow command not implemented.\n");
    break;
  }

  // XXX If we have a next-in-flow, then we're not complete
  if (mNextInFlow) {
    aStatus = NS_FRAME_NOT_COMPLETE;
  }
  return rv;
}

NS_METHOD nsTableRowGroupFrame::IR_RowGroupInserted(nsIPresContext&        aPresContext,
                                                    nsHTMLReflowMetrics&   aDesiredSize,
                                                    RowGroupReflowState&   aReflowState,
                                                    nsReflowStatus&        aStatus,
                                                    nsTableRowGroupFrame * aInsertedFrame,
                                                    PRBool                 aReplace)
{
  if (PR_TRUE==gsDebugIR) printf("TIF IR: IR_RowGroupInserted for frame %p\n", aInsertedFrame);
  nsresult rv = AddFrame(aReflowState.reflowState, aInsertedFrame);
  if (NS_FAILED(rv))
    return rv;
  
  aReflowState.tableFrame->InvalidateCellMap();
  aReflowState.tableFrame->InvalidateColumnCache();

  return rv;
}

NS_METHOD nsTableRowGroupFrame::IR_RowGroupRemoved(nsIPresContext&        aPresContext,
                                                   nsHTMLReflowMetrics&   aDesiredSize,
                                                   RowGroupReflowState& aReflowState,
                                                   nsReflowStatus&        aStatus,
                                                   nsTableRowGroupFrame * aDeletedFrame)
{
  if (PR_TRUE==gsDebugIR) printf("TIF IR: IR_RowGroupRemoved for frame %p\n", aDeletedFrame);
  nsresult rv = mFrames.DestroyFrame(aPresContext, aDeletedFrame);
  aReflowState.tableFrame->InvalidateCellMap();
  aReflowState.tableFrame->InvalidateColumnCache();

  // if any column widths have to change due to this, rebalance column widths
  //XXX need to calculate this, but for now just do it
  aReflowState.tableFrame->InvalidateColumnWidths();

  return rv;
}

NS_METHOD nsTableRowGroupFrame::IR_RowInserted(nsIPresContext&      aPresContext,
                                               nsHTMLReflowMetrics& aDesiredSize,
                                               RowGroupReflowState& aReflowState,
                                               nsReflowStatus&      aStatus,
                                               nsTableRowFrame *    aInsertedFrame,
                                               PRBool               aReplace)
{
  if (PR_TRUE==gsDebugIR) printf("\nTRGF IR: IR_RowInserted\n");
  nsresult rv = AddFrame(aReflowState.reflowState, (nsIFrame*)aInsertedFrame);
  if (NS_FAILED(rv))
    return rv;

  if (PR_TRUE==aReflowState.tableFrame->RequiresPass1Layout())
  {
    // do a pass-1 layout of all the cells in the inserted row
    //XXX: check the table frame to see if we can skip this
    rv = ReflowMappedChildren(aPresContext, aDesiredSize, aReflowState, aStatus, 
                              aInsertedFrame, eReflowReason_Initial, PR_FALSE);
    if (NS_FAILED(rv))
      return rv;
  }

  aReflowState.tableFrame->InvalidateCellMap();
  aReflowState.tableFrame->InvalidateColumnCache();

  return rv;
}

NS_METHOD nsTableRowGroupFrame::DidAppendRow(nsTableRowFrame *aRowFrame)
{
  if (PR_TRUE==gsDebugIR) printf("\nTRGF IR: DidAppendRow\n");
  nsresult rv=NS_OK;
  /* need to make space in the cell map.  Remeber that row spans can't cross row groups
     once the space is made, tell the row to initizalize its children.  
     it will automatically find the row to initialize into.
     but this is tough because a cell in aInsertedFrame could have a rowspan
     which must be respected if a subsequent row is appended.
  */
  rv = aRowFrame->InitChildren();
  return rv;
}

// support method that tells us if there are any rows in the table after our rows
// returns PR_TRUE if there are no rows after ours
PRBool nsTableRowGroupFrame::NoRowsFollow()
{
  // XXX This method doesn't play well with the tree widget.
  PRBool result = PR_TRUE;
  nsIFrame *nextSib=nsnull;
  GetNextSibling(&nextSib);
  while (nsnull!=nextSib)
  {
    const nsStyleDisplay *sibDisplay;
    nextSib->GetStyleData(eStyleStruct_Display, ((const nsStyleStruct *&)sibDisplay));
    if ((NS_STYLE_DISPLAY_TABLE_HEADER_GROUP == sibDisplay->mDisplay) ||
        (NS_STYLE_DISPLAY_TABLE_FOOTER_GROUP == sibDisplay->mDisplay) ||
        (NS_STYLE_DISPLAY_TABLE_ROW_GROUP    == sibDisplay->mDisplay))
    {
      nsIFrame *childFrame=nsnull;
      nextSib->FirstChild(nsnull, &childFrame);
      while (nsnull!=childFrame)
      {
        const nsStyleDisplay *childDisplay;
        childFrame->GetStyleData(eStyleStruct_Display, ((const nsStyleStruct *&)childDisplay));
        if (NS_STYLE_DISPLAY_TABLE_ROW == childDisplay->mDisplay)
        { // found a row 
          result = PR_FALSE;
          break;
        }
        childFrame->GetNextSibling(&childFrame);
      }
    }
    nextSib->GetNextSibling(&nextSib);
  }
  if (PR_TRUE==gsDebugIR) printf("\nTRGF IR: NoRowsFollow returning %d\n", result);
  return result;
}

NS_METHOD nsTableRowGroupFrame::GetHeightOfRows(nscoord& aResult)
{
  // the rows in rowGroupFrame need to be expanded by rowHeightDelta[i]
  // and the rowgroup itself needs to be expanded by SUM(row height deltas)
  nsIFrame * rowFrame=nsnull;
  nsresult rv = FirstChild(nsnull, &rowFrame);
  while ((NS_SUCCEEDED(rv)) && (nsnull!=rowFrame))
  {
    const nsStyleDisplay *rowDisplay;
    rowFrame->GetStyleData(eStyleStruct_Display, ((const nsStyleStruct *&)rowDisplay));
    if (NS_STYLE_DISPLAY_TABLE_ROW == rowDisplay->mDisplay)
    { 
      nsRect rowRect;
      rowFrame->GetRect(rowRect);
      aResult += rowRect.height;
    }
    else if (NS_STYLE_DISPLAY_TABLE_ROW_GROUP == rowDisplay->mDisplay)
    {
      ((nsTableRowGroupFrame*)rowFrame)->GetHeightOfRows(aResult);
    }
    GetNextFrame(rowFrame, &rowFrame);
  }
  return NS_OK;
}

// since we know we're doing an append here, we can optimize
NS_METHOD nsTableRowGroupFrame::IR_RowAppended(nsIPresContext&      aPresContext,
                                               nsHTMLReflowMetrics& aDesiredSize,
                                               RowGroupReflowState& aReflowState,
                                               nsReflowStatus&      aStatus,
                                               nsTableRowFrame *    aAppendedFrame)
{
  if (PR_TRUE==gsDebugIR) printf("\nTRGF IR: IR_RowAppended\n");
  // hook aAppendedFrame into the child list
  nsresult rv = AddFrame(aReflowState.reflowState, (nsIFrame*)aAppendedFrame);
  if (NS_FAILED(rv))
    return rv;

  /* we have 2 paths to choose from.  If we know that aAppendedFrame is
   * the last row in the table, we can optimize.  Otherwise, we have to
   * treat it like an insert
   */
  if (PR_TRUE==NoRowsFollow())
  { // aAppendedRow is the last row, so do the optimized route
    // account for the cells in the row aAppendedFrame
    // this will add the content of the rowgroup to the cell map
    rv = DidAppendRow(aAppendedFrame);
    if (NS_FAILED(rv))
      return rv;

    if (PR_TRUE==aReflowState.tableFrame->RequiresPass1Layout())
    {
      // do a pass1 reflow of the new row
      //XXX: check the table frame to see if we can skip this
      rv = ReflowMappedChildren(aPresContext, aDesiredSize, aReflowState, aStatus, 
                                aAppendedFrame, eReflowReason_Initial, PR_FALSE);
      if (NS_FAILED(rv))
        return rv;
    }

    // if any column widths have to change due to this, rebalance column widths
    //XXX need to calculate this, but for now just do it
    aReflowState.tableFrame->InvalidateColumnWidths();  
  }
  else
  {
    // do a pass1 reflow of the new row
    //XXX: check the table frame to see if we can skip this
    rv = ReflowMappedChildren(aPresContext, aDesiredSize, aReflowState, aStatus, 
                              aAppendedFrame, eReflowReason_Initial, PR_FALSE);
    if (NS_FAILED(rv))
      return rv;

    aReflowState.tableFrame->InvalidateCellMap();
    aReflowState.tableFrame->InvalidateColumnCache();
  }

  return rv;
}

NS_METHOD nsTableRowGroupFrame::IR_RowRemoved(nsIPresContext&      aPresContext,
                                              nsHTMLReflowMetrics& aDesiredSize,
                                              RowGroupReflowState& aReflowState,
                                              nsReflowStatus&      aStatus,
                                              nsTableRowFrame *    aDeletedFrame)
{
  if (PR_TRUE==gsDebugIR) printf("\nTRGF IR: IR_RowRemoved\n");
  nsresult rv = mFrames.DestroyFrame(aPresContext, (nsIFrame *)aDeletedFrame);
  if (NS_SUCCEEDED(rv))
  {
    aReflowState.tableFrame->InvalidateCellMap();
    aReflowState.tableFrame->InvalidateColumnCache();

    // if any column widths have to change due to this, rebalance column widths
    //XXX need to calculate this, but for now just do it
    aReflowState.tableFrame->InvalidateColumnWidths();
  }

  return rv;
}

NS_METHOD nsTableRowGroupFrame::IR_TargetIsChild(nsIPresContext&      aPresContext,
                                                 nsHTMLReflowMetrics& aDesiredSize,
                                                 RowGroupReflowState& aReflowState,
                                                 nsReflowStatus&      aStatus,
                                                 nsIFrame *           aNextFrame)

{
  nsresult rv;
  if (PR_TRUE==gsDebugIR) printf("\nTRGF IR: IR_TargetIsChild\n");
  // XXX Recover state

  // Remember the old rect
  nsRect  oldKidRect;
  aNextFrame->GetRect(oldKidRect);

  // Pass along the reflow command
  // XXX Correctly compute the available space...
  nsSize  availSpace(aReflowState.reflowState.availableWidth, aReflowState.reflowState.availableHeight);
  nsHTMLReflowState   kidReflowState(aPresContext, aReflowState.reflowState, aNextFrame, availSpace);
  nsHTMLReflowMetrics desiredSize(nsnull);

  rv = ReflowChild(aNextFrame, aPresContext, desiredSize, kidReflowState, aStatus);
  // XXX Check aStatus to see if the frame is complete...

  // Resize the row frame
  nsRect  kidRect;
  aNextFrame->GetRect(kidRect);
  aNextFrame->SizeTo(desiredSize.width, desiredSize.height);

  // Adjust the frames that follow...
  AdjustSiblingsAfterReflow(aPresContext, aReflowState, aNextFrame, desiredSize.height -
                            oldKidRect.height);

  // Return of desired size
  aDesiredSize.width = aReflowState.reflowState.availableWidth;
  aDesiredSize.height = aReflowState.y;

  // XXX If we have a next-in-flow, then we're not complete
  if (mNextInFlow) {
    aStatus = NS_FRAME_NOT_COMPLETE;
  }

  return rv;
}

NS_METHOD nsTableRowGroupFrame::IR_StyleChanged(nsIPresContext&      aPresContext,
                                                nsHTMLReflowMetrics& aDesiredSize,
                                                RowGroupReflowState& aReflowState,
                                                nsReflowStatus&      aStatus)
{
  if (PR_TRUE==gsDebugIR) printf("TRGF: IR_StyleChanged for frame %p\n", this);
  nsresult rv = NS_OK;
  // we presume that all the easy optimizations were done in the nsHTMLStyleSheet before we were called here
  // XXX: we can optimize this when we know which style attribute changed
  aReflowState.tableFrame->InvalidateFirstPassCache();
  return rv;
}

NS_IMETHODIMP
nsTableRowGroupFrame::GetFrameType(nsIAtom** aType) const
{
  NS_PRECONDITION(nsnull != aType, "null OUT parameter pointer");
  *aType = nsLayoutAtoms::tableRowGroupFrame; 
  NS_ADDREF(*aType);
  return NS_OK;
}


/* ----- global methods ----- */

nsresult 
NS_NewTableRowGroupFrame(nsIFrame** aNewFrame)
{
  NS_PRECONDITION(aNewFrame, "null OUT ptr");
  if (nsnull == aNewFrame) {
    return NS_ERROR_NULL_POINTER;
  }
  nsTableRowGroupFrame* it = new nsTableRowGroupFrame;
  if (nsnull == it) {
    return NS_ERROR_OUT_OF_MEMORY;
  }
  *aNewFrame = it;
  return NS_OK;
}

NS_IMETHODIMP
nsTableRowGroupFrame::GetFrameName(nsString& aResult) const
{
  return MakeFrameName("TableRowGroup", aResult);
}