Sort columns by the image index of the column


This code was contributed by Mark Findlay.
// This is a simple modification of the text sorting routine by
// Zafir Anjum. (See "Sorting the list based on text in any column")

// It sorts the list based on the image index of the column being 
// sorted. You must only call this function when sorting a column
// that has an image associated with it.
// I added an additional helper function GetItemImageIndex() which
// simply returns the image index for the row and column specified.

// GetItemImageIndex
// return the image index of the selected row and col
int CMyListCtrl::GetItemImageIndex(int nRow, int nCol/*=0*)
    LV_ITEM lv = {0};
	lv.mask = LVIF_IMAGE;
	lv.iItem = nRow;
	lv.iSubItem = nCol;

	GetItem( &lv );

    return lv.iImage;

// Sort by image index of column
// This function is a simple modification of the text sorting function
// written by Zafir Anjum.
// SortInImageOrder	- Sort the list based on image index of column
// Returns		- Returns true for success
// nCol			- column that contains the text to be sorted
// bAscending	- indicate sort order
// nLow			- row to start scanning from - default row is 0
// nHigh		- row to end scan. -1 indicates last row
BOOL CMyListCtrl::SortInImageOrder(int nCol, BOOL bAscending, int nLow/*=0*, int nHigh/*=-1*)
    BOOL bRet = FALSE;

	if( nCol >= ((CHeaderCtrl*)GetDlgItem(0))->GetItemCount() )
		return FALSE;
	if( nHigh == -1 ) nHigh = GetItemCount() - 1;
	int nLo = nLow;   
	int nHi = nHigh;
	int nMidItem;
	if( nHi <= nLo ) 
        return FALSE;
	nMidItem = GetItemImageIndex( (nLo+nHi)/2, nCol );
	// loop through the list until indices cross
	while( nLo <= nHi )
		// arrsRowText will hold all column text for one row
		CStringArray arrsRowText;
		// find the first element that is greater than or equal to 
		// the partition element starting from the left Index.
		if( bAscending )
			while( ( nLo < nHigh ) && (GetItemImageIndex(nLo, nCol) < nMidItem ) )
			while( ( nLo < nHigh ) && (GetItemImageIndex(nLo, nCol) > nMidItem ) )
		// find an element that is smaller than or equal to 
		// the partition element starting from the right Index.
		if( bAscending )
			while( ( nHi > nLow ) && (GetItemImageIndex(nHi, nCol) > nMidItem ) )
			while( ( nHi > nLow ) && (GetItemImageIndex(nHi, nCol) < nMidItem ) )
		// if the indexes have not crossed, swap                
		// and if the items are not equal
		if( nLo <= nHi )
			// swap only if the items are not equal
			if(GetItemImageIndex(nLo, nCol) != GetItemImageIndex(nHi, nCol) )
				// swap the rows
                LV_ITEM lvitemlo = {0};
                LV_ITEM lvitemhi = {0};
                // Get the column count
				int nColCount =
				arrsRowText.SetSize( nColCount );
                // Load string array with text items of Lo row
				int i;
				for( i=0; i < nColCount; i++)
							arrsRowText[i] = GetItemText(nLo, i);
                // Setup Lo item structure
				lvitemlo.mask = LVIF_IMAGE | LVIF_STATE;

                // lParam only avail on col zero
                if (nCol == 0)
                    lvitemlo.mask |= LVIF_PARAM;

				lvitemlo.iItem = nLo;
				lvitemlo.iSubItem = nCol; // 10/29/97 0;
				lvitemlo.stateMask = 
                        LVIS_CUT            | LVIS_DROPHILITED      |
						LVIS_FOCUSED        | LVIS_SELECTED         |

                // duplicate to hi item except for iItem index
				lvitemhi = lvitemlo;
				lvitemhi.iItem = nHi;
				lvitemhi.iSubItem = nCol; // 10/29/97

                // get the current lo and hi items
				GetItem( &lvitemlo );
				GetItem( &lvitemhi );
                // set item text of lo to item text of hi
				for( i=0; i< nColCount; i++)
				    SetItemText(nLo, i, GetItemText(nHi, i) );
                // save hi item
				lvitemhi.iItem = nLo;
				bRet = SetItem( &lvitemhi );
                // set item text of hi to item text of lo
				for( i=0; i< nColCount; i++)
				    SetItemText(nHi, i, arrsRowText[i]);
                // save lo item
				lvitemlo.iItem = nHi;
                lvitemhi.iSubItem = nCol; // 10/29/97
                bRet = SetItem( &lvitemlo );
	// If the right index has not reached the left side of array
	// must now sort the left partition.
	if( nLow < nHi )
		SortInImageOrder( nCol, bAscending , nLow, nHi);
	// If the left index has not reached the right side of array
	// must now sort the right partition.
	if( nLo < nHigh )
		SortInImageOrder( nCol, bAscending , nLo, nHigh );
	return TRUE;


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