HexEdit - Window Binary File Editor

/*****************************************************************************
    COPYRIGHT (C) 2000-2001, Ken Bertelson <kbertelson@yahoo.com>


*****************************************************************************/
#include "stdafx.h"
#include "TreeColumn.h"

#include "GridTreeCell.H"

#ifdef _DEBUG
#undef THIS_FILE
static char THIS_FILE[]=__FILE__;
#define new DEBUG_NEW
#endif

//////////////////////////////////////////////////////////////////////
// Construction/Destruction
//////////////////////////////////////////////////////////////////////

CTreeColumn::CTreeColumn()
{
    // tree cell data initialization
    m_nFormat = DT_LEFT|DT_VCENTER|DT_SINGLELINE|DT_END_ELLIPSIS;
    m_crBkClr = CLR_DEFAULT;
    m_crFgClr = CLR_DEFAULT;
    m_64Param  = 0;
    m_plfFont = NULL;

    // tree properties initialization
    m_pGrid = NULL;
    m_pRuntimeClassTreeCell = NULL;
    m_iColumnWithTree = -1; // no column draws the tree
    m_bTreeUsesImages = FALSE;
    m_bShowTreeLines = TRUE;

    m_iFixedRowCount = -1;
    m_iRowCount = -1;
    m_bAllowDraw = FALSE;   // prevents crash during reset
    m_crTreeLineColour = ::GetSysColor(COLOR_3DSHADOW);
    m_nDefTreeIndent = 10;
    m_pEditWnd = NULL;
}

CTreeColumn::~CTreeColumn()
{
    if( m_plfFont != NULL)
        delete m_plfFont;
}

/*****************************************************************************
Sets up a column to be drawn with + - tree controls w/ indenting.  Text
is automatically indented.  Rows expand and collapse as appropriate

3/2001:  Tree can be in fixed column, too

*****************************************************************************/
BOOL CTreeColumn::TreeSetup(  CGridCtrl* apGridCtrl,  // tree acts on a column in this grid
                            int aiColumn,       // which column has tree
                            int aiTotalRows,    // total number of rows in the
                                                //  tree if totally expanded
                            int aiFixedRowCount,// Set fixed row count now, too
                                                //  Grid total rows=aiTotalRows+aiFixedRowCount
                            const unsigned char* apucTreeLevelAry,    // Tree Level data array --
                                                //  must have aiTotalRows of entries
                            BOOL abShowTreeLines,   // T=show tree (not grid) lines; F=no tree lines
                            BOOL abUseImages,   // T=use 1st 3 images from already set image list
                                                //  to display folder graphics
                            CRuntimeClass* apRuntimeClass)   // can use your special
                                                //  CGridTreeCellBase-derived class
// returns:  success / fail
{
    ASSERT( apGridCtrl != NULL);
    ASSERT( aiColumn < apGridCtrl->GetColumnCount());

    m_pRuntimeClassTreeCell = apRuntimeClass;
    if( m_pRuntimeClassTreeCell == NULL)  // default can hold data
       m_pRuntimeClassTreeCell = RUNTIME_CLASS(CGridTreeCell);
    if (!m_pRuntimeClassTreeCell->IsDerivedFrom(RUNTIME_CLASS(CGridTreeCellBase)))
    {
        ASSERT( FALSE);
        return FALSE;
    }

    m_pGrid = apGridCtrl;
    m_bAllowDraw = FALSE;   // prevents crash during reset
    BOOL bRC = TRUE;

    m_iFixedRowCount = aiFixedRowCount;
    m_iRowCount = aiTotalRows + aiFixedRowCount;
    m_iColumnWithTree = aiColumn;

    m_pGrid->SetFixedRowCount( m_iFixedRowCount);
    m_pGrid->SetRowCount( m_iRowCount);

    if( aiTotalRows > 0)
    {
        ASSERT( apucTreeLevelAry != NULL);

        // retain old cell properties: establishes size for
        //  tree drawing box based on current font
        CGridTreeCell GridCellCopy;
        GridCellCopy.SetTreeColumn( this);
        CGridCellBase* pCurrCell = m_pGrid->GetCell( 0, m_iColumnWithTree);
        if (pCurrCell)
            GridCellCopy = *pCurrCell;

        // copy all data while replacing cells to tree cell type
        for( int i1=0; i1 < aiTotalRows; i1++)
        {
            int iCellRow = m_iFixedRowCount + i1;


            if( !m_pGrid->SetCellType(   iCellRow,
                                m_iColumnWithTree,
                                m_pRuntimeClassTreeCell ) )
            {
                bRC = FALSE;
                break;
            }

            CGridTreeCell* pGridTreeCell = (CGridTreeCell*)m_pGrid->GetCell( iCellRow, m_iColumnWithTree);
            if( pGridTreeCell != NULL)
            {
                pGridTreeCell->SetTreeColumn( this);
                pGridTreeCell->SetLevelAndHide( *apucTreeLevelAry );
            }

            apucTreeLevelAry++;
        }

        SetTreeUsesImages( abUseImages);   // T=use images
        SetTreeLines( abShowTreeLines);    // T=show tree lines
    }

    m_bAllowDraw = TRUE;
    m_pGrid->Invalidate();
    return bRC;
}

/*****************************************************************************
3/2001:   Allows one to add to the existing tree structure.   Repeatedly
calling TreeSetup() with different tree configurations was the only way to
change the tree structure with the original implementation, but had the
disadvantage of destroying cell contents.  The original implementation
forced you to NOT store data directly in grid cells if you wished to
change the tree.

No validation of the tree branch "levels" done.  Drawing code assumes
a parent / child relationship of tree nodes.  Thus, if the lines of
the tree don't look right, make sure that the parent / child relationship
is not violated.

*****************************************************************************/
int CTreeColumn::InsertTreeBranch(  
                            const unsigned char* apucTreeLevelAry,    // Tree Level data array --
                                                            //  must have aiNbrElements of entries
                            int aiNbrElements,  // NUmber of tree elements to add
                            int aiRow,      // insert tree elements beginning at this row
                                            //  If -1, append to end; If 0, Insert
                                            //  at top no matter how many fixed rows
                            BOOL abRedraw)  // T=redraw; F=don't
// returns:  row where elements inserted; -1 on error
{
    ASSERT( apucTreeLevelAry != NULL);
    ASSERT( aiNbrElements >= 0);
    ASSERT( aiRow >= -1);
    ASSERT( m_pGrid != NULL);       // Must call TreeSetup(), first
    ASSERT( m_iFixedRowCount >= 0);
    ASSERT( m_pRuntimeClassTreeCell != NULL);

    if( aiNbrElements <= 0)
        return -1;

    // if user specified 0 or -1, adjust
    int iRowForAppend = 0;
    if( m_iRowCount <= m_iFixedRowCount)
        aiRow = -1; // if no non-fixed rows, then gotta append

    if( aiRow <= -1)
    {
        iRowForAppend = -1;
        aiRow = m_iRowCount;
    }
    else if( aiRow < m_iFixedRowCount)
        aiRow = m_iFixedRowCount;
        
    m_bAllowDraw = FALSE;   // prevents crash during reset

    // retain old cell properties: establishes size for
    //  tree drawing box based on current font
    CGridTreeCell GridCellCopy;
    GridCellCopy.SetTreeColumn( this);
    CGridCellBase* pCurrCell = m_pGrid->GetCell( m_iRowCount-1, m_iColumnWithTree);
    if (pCurrCell)
        GridCellCopy = *pCurrCell;

    // insert rows while replacing tree column cells to tree cell type
    int iCellRow = aiRow;
    int i1;
    for( i1=0; i1 < aiNbrElements; i1++)
    {
        // CGridCtrl's InsertRow() requires a -1 to append values to
        //  the end of the grid
        if( iRowForAppend != -1)
            iRowForAppend = iCellRow;

        if( m_pGrid->InsertRow( "", iRowForAppend) < 0)
        {
            aiRow = -1; // error
            break;
        }

        if( !m_pGrid->SetCellType(   iCellRow,
                            m_iColumnWithTree,
                            m_pRuntimeClassTreeCell ) )
        {
            aiRow = -1; // error
            break;
        }

        CGridTreeCell* pGridTreeCell = (CGridTreeCell*)m_pGrid->GetCell( iCellRow, m_iColumnWithTree);
        if( pGridTreeCell != NULL)
        {
            pGridTreeCell->SetTreeColumn( this);
            pGridTreeCell->SetLevelAndHide( *apucTreeLevelAry );
            pGridTreeCell->SetViewable( TRUE);
        }

        iCellRow++;
        m_iRowCount++;
        apucTreeLevelAry++;
    }
    ASSERT( m_iRowCount == m_pGrid->GetRowCount() );

    // have to re-number all cells below insertion point
    if( aiRow > 0)
    {
        int iRow;
        int iColumnCount = m_pGrid->GetColumnCount();
        for( iRow=iCellRow; iRow < m_iRowCount; iRow++)
        {
            int iCol;
            for (iCol = 0; iCol < iColumnCount; iCol++)
            {
                CGridCellBase* pGridCellBase = m_pGrid->GetCell( iRow, iCol);
                if( pGridCellBase != NULL)
                {
                    pGridCellBase->SetCoords( iRow, iCol);
                }
            }
        }
    }



    m_bAllowDraw = TRUE;
    TreeRefreshRows();
    if( abRedraw)
        m_pGrid->Invalidate();

    return aiRow;
}

/*****************************************************************************
This may delete one or more rows depending on the makeup of the tree branch.
It's analagous to deleting a file directory with all files and sub-directories
deleted, too.

*****************************************************************************/
int CTreeColumn::DeleteTreeBranch( int aiRow,  // Row that the tree branch begins on
                                   BOOL abRedraw) // T=redraw; F=don't
// returns:  nbr of rows deleted
{
    ASSERT( aiRow >= -1);
    ASSERT( m_pGrid != NULL);       // Must call TreeSetup(), first

    if( aiRow < m_iFixedRowCount 
        || aiRow >= m_iRowCount)
        return 0;

    int iRowDeleteCount = 0;
    m_bAllowDraw = FALSE;   // prevents crash during reset

    // get level of initial row to delete from tree
    CGridTreeCell* pGridTreeCell = (CGridTreeCell*)m_pGrid->GetCell( aiRow, m_iColumnWithTree);
    unsigned char ucLevelCurrent = CHAR_MAX;
    
    if( pGridTreeCell != NULL)
    {
        // delete just the parent
        ucLevelCurrent = pGridTreeCell->GetLevel();
        if( m_pGrid->DeleteRow( aiRow) )
        {
            iRowDeleteCount++;
            m_iRowCount--;
        }
    }

    // see if any children need to be deleted, too
    unsigned char ucLevel;
    while( aiRow < m_iRowCount)
    {
        pGridTreeCell = (CGridTreeCell*)m_pGrid->GetCell( aiRow, m_iColumnWithTree);
        if( pGridTreeCell == NULL)
            break;

        ucLevel = pGridTreeCell->GetLevel();
        if( ucLevel <= ucLevelCurrent)
            break;

        if( !m_pGrid->DeleteRow( aiRow) )
            break;

        iRowDeleteCount++;
        m_iRowCount--;
    }
    ASSERT( m_iRowCount == m_pGrid->GetRowCount() );
    
    // have to re-number all cells below deletion point
    if( iRowDeleteCount > 0)
    {
        int iRow;
        int iColumnCount = m_pGrid->GetColumnCount();
        for( iRow=aiRow; iRow < m_iRowCount; iRow++)
        {
            int iCol;
            for (iCol = 0; iCol < iColumnCount; iCol++)
            {
                CGridCellBase* pGridCellBase = m_pGrid->GetCell( iRow, iCol);
                if( pGridCellBase != NULL)
                {
                    pGridCellBase->SetCoords( iRow, iCol);
                }
            }
        }
    }
    
    m_bAllowDraw = TRUE;
    TreeRefreshRows();
    if( abRedraw)
        m_pGrid->Invalidate();

    return iRowDeleteCount;
}

void CTreeColumn::SetTreeUsesImages( BOOL abUseImages)   // T=use images
{
#ifdef _DEBUG
    ASSERT( m_iColumnWithTree >= 0);
    ASSERT( m_pGrid != NULL);

    if( abUseImages
        && m_pGrid->GetImageList() == NULL)
        ASSERT( FALSE);     // must call SetImageList() first
#endif

    m_bTreeUsesImages = abUseImages;

    if( abUseImages)
    {
        // make sure that items have an image associated with it for
        //  autosize column width calculations
        ASSERT( m_iRowCount > 0); // call SetRowCount() before this
        ASSERT( m_iColumnWithTree >= 0);
        for( int i1=m_pGrid->GetFixedRowCount(); i1 < m_iRowCount; i1++)
        {
            m_pGrid->SetItemImage( i1, m_iColumnWithTree, 0);
        }
    }
}

void CTreeColumn::SetTreeLines( BOOL abShowTreeLines)   // T=show tree lines
{
    ASSERT( m_iColumnWithTree >= 0);
    m_bShowTreeLines = abShowTreeLines;
}

unsigned char CTreeColumn::GetTreeLevel(  int aiRow)  // row
// returns:  tree level, =0 if invalid input
{
    ASSERT( m_pGrid != NULL);
    ASSERT( aiRow >= 0
            && aiRow < m_iRowCount );
    ASSERT( m_iColumnWithTree >= 0);

    CGridTreeCell* pGridTreeCell = (CGridTreeCell*)m_pGrid->GetCell( aiRow, m_iColumnWithTree);
    if( pGridTreeCell != NULL)
        return pGridTreeCell->GetLevel();

    return 0;
}

BOOL CTreeColumn::IsTreeRowDisplayed(  int aiRow)  // row
// returns:  T=tree row is displayed
{
    ASSERT( m_pGrid != NULL);
    ASSERT( aiRow >= 0
            && aiRow < m_iRowCount );
    ASSERT( m_iColumnWithTree >= 0);

    CGridTreeCell* pGridTreeCell = (CGridTreeCell*)m_pGrid->GetCell( aiRow, m_iColumnWithTree);
    if( pGridTreeCell != NULL)
        return pGridTreeCell->IsViewable();

    return FALSE;
}

unsigned char CTreeColumn::GetLevelAndHide( int aiRow)
// returns:  tree level, =0 if invalid input
{
    ASSERT( m_pGrid != NULL);
    ASSERT( aiRow >= 0
            && aiRow < m_iRowCount );
    ASSERT( m_iColumnWithTree >= 0);

    CGridTreeCell* pGridTreeCell = (CGridTreeCell*)m_pGrid->GetCell( aiRow, m_iColumnWithTree);
    if( pGridTreeCell != NULL)
        return pGridTreeCell->GetLevelAndHide();

    return 0;
}

/*****************************************************************************
Examines saved array show / hide bit to determine if a row should display.
There is a one-for-one mapping of these bits to total rows

*****************************************************************************/
void CTreeColumn::TreeRefreshRows()
{
    ASSERT( m_pGrid != NULL);
    ASSERT( m_iColumnWithTree >= 0);

    // hide / show each row
    for( int i1=m_iFixedRowCount; i1 < m_iRowCount; i1++)
    {
        CGridTreeCell* pGridTreeCell = (CGridTreeCell*)m_pGrid->GetCell( i1, m_iColumnWithTree);
        if( pGridTreeCell == NULL)
            return;

        if( pGridTreeCell->IsViewable() )
        {
            if( m_pGrid->GetRowHeight( i1) < m_pGrid->GetDefCellHeight() )
                m_pGrid->SetRowHeight( i1, m_pGrid->GetDefCellHeight() );
        }
        else
        {
            if( m_pGrid->GetRowHeight( i1) > 0 )
                m_pGrid->SetRowHeight( i1, 0);
        }

    }

    if (::IsWindow( m_pGrid->m_hWnd) && m_bAllowDraw)
    {
        m_pGrid->Invalidate();
    }

}
/*****************************************************************************
Callable by class consumer to prepare one's own data array of tree info to
display something reasonable.   High order Bits of the tree display data are
modified.

*****************************************************************************/
void CTreeColumn::TreeDataPrepOutline(unsigned char aucLevel, // level to display >= 0x80 displays all
                                    int aiIndex,            // Index to tree display data to modify
                                    int aiNbrElements)      // nbr of elements in tree display data
{
    ASSERT( aucLevel > 0);
    ASSERT( m_iColumnWithTree >= 0);
    ASSERT( aiIndex >= 0 );
    ASSERT( aiNbrElements > 0);
    ASSERT( m_pGrid != NULL);
    ASSERT( aiIndex + aiNbrElements <= m_iRowCount - m_iFixedRowCount );

    int i1;

    if( aucLevel >= 0x80)
    {
        for( i1=0; i1 < aiNbrElements; i1++)
        {
            int iCellRow = m_iFixedRowCount + aiIndex + i1;

            CGridTreeCell* pGridTreeCell = (CGridTreeCell*)m_pGrid->GetCell( iCellRow, m_iColumnWithTree);
            if( pGridTreeCell == NULL)
                return;

            pGridTreeCell->SetViewable( TRUE);
        }
    }
    else
    {
        for( i1=0; i1 < aiNbrElements; i1++)
        {
            int iCellRow = m_iFixedRowCount + aiIndex + i1;

            CGridTreeCell* pGridTreeCell = (CGridTreeCell*)m_pGrid->GetCell( iCellRow, m_iColumnWithTree);
            if( pGridTreeCell == NULL)
                return;

            if( pGridTreeCell->GetLevel() <= aucLevel)
                pGridTreeCell->SetViewable( TRUE);
            else
                pGridTreeCell->SetViewable( FALSE);
        }
    }
}

/*****************************************************************************
Like MS-Word's outline feature.  Can show 1st level of outline all the
way up to 126 levels or all

*****************************************************************************/
void CTreeColumn::TreeDisplayOutline( unsigned char aucLevel )    // level to display >= 0x80 displays all
{
    ASSERT( aucLevel > 0);
    ASSERT( m_pGrid != NULL);
    ASSERT( m_iColumnWithTree >= 0);
    if( m_iColumnWithTree < 0)
        return;

    int iNbrElements = m_iRowCount - m_iFixedRowCount;

    if( iNbrElements > 0)
    {
        TreeDataPrepOutline(aucLevel,         // level to display >= 0x80 displays all
                            0,                // Index to tree display data to modify
                            iNbrElements);    // nbr of elements in tree display data
    }

    TreeRefreshRows();

}

/*****************************************************************************
Expands a branch 1 and only 1 level -- like when a user clicks on "+" box
in windows explorer tree.  Note that it doesn't check whether adjacent nodes
are properply represented, it just does the expand

*****************************************************************************/
void CTreeColumn::TreeDataExpandOneLevel( int aiGridRow)
{
    ASSERT( m_iColumnWithTree >= 0);
    ASSERT( m_pGrid != NULL);

    ASSERT( aiGridRow >= m_iFixedRowCount
            && aiGridRow < m_iRowCount);

    // display desired node and save its level and make visible
    CGridTreeCell* pGridTreeCell = (CGridTreeCell*)m_pGrid->GetCell( aiGridRow, m_iColumnWithTree);
    if( pGridTreeCell == NULL)
        return;

    unsigned char ucLevelCurrent = pGridTreeCell->GetLevel();
    if( ucLevelCurrent <= 0)
        return; // don't expand or collapse items not part of the tree
    pGridTreeCell->SetViewable( TRUE);

    unsigned char ucLevel;
    int i1;
    for( i1 = aiGridRow + 1; i1 < m_iRowCount; i1++)
    {
        CGridTreeCell* pGridTreeCell = (CGridTreeCell*)m_pGrid->GetCell( i1, m_iColumnWithTree);
        if( pGridTreeCell == NULL)
            return;

        ucLevel = pGridTreeCell->GetLevel();
        if( ucLevel <= ucLevelCurrent)
            break;

        if( ucLevel == ucLevelCurrent + 1)
            pGridTreeCell->SetViewable( TRUE);
//        else
//            pGridTreeCell->SetViewable( FALSE);

    }
}

/*****************************************************************************
Collapses all levels of a branch -- not just 1 level.   Using this in
conjunction with TreeDataExpandOneLevel will get a tree grid that performs like
VC++ watch window.   Windows explorer tree differs:  it "remembers" last
expansion.

Note that it doesn't check whether adjacent nodes are properply represented, it
just does the collapse.

*****************************************************************************/
void CTreeColumn::TreeDataCollapseAllSubLevels( int aiGridRow)
{
    ASSERT( m_iColumnWithTree >= 0);
    ASSERT( m_pGrid != NULL);

    ASSERT( aiGridRow >= m_iFixedRowCount
            && aiGridRow < m_iRowCount);

    // display desired node and save its level and make visible
    CGridTreeCell* pGridTreeCell = (CGridTreeCell*)m_pGrid->GetCell( aiGridRow, m_iColumnWithTree);
    if( pGridTreeCell == NULL)
        return;

    unsigned char ucLevelCurrent = pGridTreeCell->GetLevel();
    if( ucLevelCurrent <= 0)
        return; // don't expand or collapse items not part of the tree
    pGridTreeCell->SetViewable( TRUE);

    unsigned char ucLevel;
    int i1;
    for( i1 = aiGridRow + 1; i1 < m_iRowCount; i1++)
    {
        CGridTreeCell* pGridTreeCell = (CGridTreeCell*)m_pGrid->GetCell( i1, m_iColumnWithTree);
        if( pGridTreeCell == NULL)
            return;

        ucLevel = pGridTreeCell->GetLevel();
        if( ucLevel <= ucLevelCurrent)
            break;

        pGridTreeCell->SetViewable( FALSE);

    }
}

/*****************************************************************************
Toggles tree expansion and collapsing.  Intended to be connected to a user
event

*****************************************************************************/
void CTreeColumn::TreeExpandCollapseToggle( int aiGridRow) // Grid row of node to toggle
{
    ASSERT( m_pGrid != NULL);
	m_pGrid->m_bLMouseButtonDown = FALSE;
    ASSERT( aiGridRow >= m_iFixedRowCount
            && aiGridRow < m_iRowCount);
    ASSERT( m_bAllowDraw);
    ASSERT( m_iColumnWithTree >= 0);
    if( m_iColumnWithTree < 0)
        return;

    // if last element, forget it
    if( aiGridRow + 1 >= m_iRowCount)
        return;

    // see if it needs to be expanded by looking at hide/show state of first neighbor.
    //  If first neighbor is hidden, should expand
    CGridTreeCell* pGridTreeCell = (CGridTreeCell*)m_pGrid->GetCell( aiGridRow + 1, m_iColumnWithTree);
    if( pGridTreeCell == NULL)
        return;

    if( pGridTreeCell->IsViewable() )
    {
        TreeDataCollapseAllSubLevels( aiGridRow);
		TreeRefreshRows();
    }
    else
    {
        TreeDataExpandOneLevel( aiGridRow);
		TreeRefreshRows();

		// Make sure bottom expanded row is visible (or as many of the expanded rows as possible)
		CGridTreeCell* pGridTreeCell = (CGridTreeCell*)m_pGrid->GetCell(aiGridRow, m_iColumnWithTree);
		if( pGridTreeCell == NULL)
			return;
		UCHAR lev = pGridTreeCell->GetLevel();
		int ii;
		for (ii = aiGridRow + 1; ii < m_iRowCount; ii++)
		{
			pGridTreeCell = (CGridTreeCell*)m_pGrid->GetCell(ii, m_iColumnWithTree);
			if (pGridTreeCell == NULL || pGridTreeCell->GetLevel() <= lev)
				break;
		}

		m_pGrid->EnsureVisible(ii-1, m_iColumnWithTree);
		m_pGrid->EnsureVisible(aiGridRow, m_iColumnWithTree);
    }
}

/*****************************************************************************
Should the cell identified by the row have a "+" or "-" graphic?

*****************************************************************************/
BOOL CTreeColumn::TreeCellHasPlusMinus(   int aiRow,          // row of Cell to check
                                        BOOL* apbIsPlus,    // returns:  T=Is a plus
                                        BOOL* apbIsMinus,   // returns:  T=Is a minus
                                        BOOL* apbIsLastLeaf)// returns:  T=Is Last Leaf
// returns:  T=cell has a plus or minus;  F=not
{
    ASSERT( m_pGrid != NULL);
    ASSERT( aiRow >= m_iFixedRowCount
            && aiRow < m_iRowCount);
    ASSERT( m_iColumnWithTree >= 0);
    ASSERT( apbIsPlus != NULL);
    ASSERT( apbIsMinus != NULL);
    ASSERT( apbIsLastLeaf != NULL);

    *apbIsPlus = FALSE;
    *apbIsMinus = FALSE;
    *apbIsLastLeaf = FALSE;

    int iStartPt = aiRow + 1;
    int i1;

    // get current level
    CGridTreeCell* pGridTreeCell = (CGridTreeCell*)m_pGrid->GetCell( aiRow, m_iColumnWithTree);
    if( pGridTreeCell == NULL)
        return FALSE;
    unsigned char ucLevelCurrent = pGridTreeCell->GetLevel();
    if( ucLevelCurrent <= 0)
        return FALSE;     // no tree

    BOOL bIsNextShowing = FALSE;
    unsigned char ucLevelNext = 0;


    for( i1=iStartPt; i1 < m_iRowCount; i1++)
    {
        pGridTreeCell = (CGridTreeCell*)m_pGrid->GetCell( i1, m_iColumnWithTree);
        if( pGridTreeCell == NULL)
            return FALSE;

        bIsNextShowing = pGridTreeCell->IsViewable();
        ucLevelNext = pGridTreeCell->GetLevel();

        if( ucLevelCurrent >= ucLevelNext )
        {
            break;
        }

        if( !bIsNextShowing
            && ucLevelNext == ucLevelCurrent + 1)
        {
            *apbIsPlus = TRUE;
        }

    }

    // final attribute setting now that enough data has been examined
    if( i1 > iStartPt
        && !*apbIsPlus)
    {
        *apbIsMinus = TRUE;
    }

    if( !bIsNextShowing
        || ucLevelCurrent > ucLevelNext
        || i1 >= m_iRowCount )  // hit last element
        *apbIsLastLeaf = TRUE;

    return *apbIsMinus || *apbIsPlus;
}

BOOL CTreeColumn::GetTreeUsesNbrImages() const
{
    return CGridTreeCellBase::TREE_IMAGE_FENCE;
}