Tab stops in a combo box

Magnus_Johannesson/FSVAB/FRONTEC.FRONTEC@notes.frontec.se
Thursday, November 07, 1996


Environment: VC++ 4.0, Win 95 (development), Win32s (target).

I want to set tab stops in a combo box, just as in a list box. Is this p=
ossible?

Magnus Johannesson
Frontec Konsulter G=F6teborg AB

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Kit Kauffmann -- kitk@mudshark.sunquest.com
Friday, November 08, 1996

>Environment: VC++ 4.0, Win 95 (development), Win32s (target).
>
>I want to set tab stops in a combo box, just as in a list box. Is this 
possible?

i believe the only way is via owner-draw, as the LB controlled by the combo 
doesn't have the LBS_USETABSTOPS style bit - here is a portion of an MFC 
tabbed combo box (use CBS_HASSTRINGS and CBS_OWNERDRAWFIXED) which should 
help get you going:

const int MaxTabs = 255;

class SQTabbedComboBox : public CComboBox
{
public:
        void Subclass( int   ID,
		       CWnd* pDlg,
		       int   firstTab,
		       ... );
protected:

        virtual void DrawItem(LPDRAWITEMSTRUCT lpDIS);

        int m_NumTabs;
        int m_TabArray[MaxTabs];
};

//
// usage might be: Subclass( ID_COMBO, this, 50, 100, -1 );
//
void SQTabbedComboBox::Subclass( int   ID,
				 CWnd* pDlg,
                                 int   firstTab,
				 ... )
{
	SubclassDlgItem( ID, pDlg );

        m_NumTabs = 0;                  // extract tab information
        int Tab = firstTab;
        va_list marker;
        va_start( marker, firstTab );   // get first tab
        int NumArgs = 0;
        while( (NumArgs < MaxTabs) && (Tab != -1) )
        {                               // add tab to list
                m_TabArray[m_NumTabs++] = Tab;
                                        // get next tab
                Tab = va_arg( marker, int );
                NumArgs++;
        }
}

void SQTabbedComboBox::DrawItem(LPDRAWITEMSTRUCT lpDIS)
{
	CString Text;
	int CurSel = (int) lpDIS->itemID;
	if( CurSel != -1 )
	{
		GetLBText( CurSel, Text );
	}
	DrawComboBoxItem( lpDIS, m_NumTabs, m_TabArray, Text );
}

//
// the fun part :)
//
void DrawComboBoxItem( LPDRAWITEMSTRUCT lpDIS,
		       int              NumTabs,
		       LPINT            pTabArray,
		       const char*      pText )
{
	if( lpDIS->itemAction & ODA_DRAWENTIRE )
        {
		CDC* pDC = CDC::FromHandle( lpDIS->hDC );
//
// combo boxes have child windows which are desktop children, not dialog
// children, so we have to clip manually
//
		CRgn Region;
		Region.CreateRectRgn( lpDIS->rcItem.left,
				      lpDIS->rcItem.top,
				      lpDIS->rcItem.right,
				      lpDIS->rcItem.bottom );
		pDC->SelectClipRgn( &Region );
		TabbedTextOut( lpDIS->rcItem.left,
			       lpDIS->rcItem.top,
			       pText,
                               strlen( pText ),
			       NumTabs,
			       pTabArray, 0 );
		Region.DeleteObject();

		if( (lpDIS->itemState & ODS_SELECTED) )
			InvertRect( lpDIS->hDC, &lpDIS->rcItem );

		if( (lpDIS->itemState & ODS_FOCUS) &&
                    (lpDIS->rcItem.left != 0) )
			InvertRect( lpDIS->hDC, &lpDIS->rcItem );

		return;
	}
	if( (lpDIS->itemAction & ODA_SELECT) )
		InvertRect( lpDIS->hDC, &lpDIS->rcItem );
}

HTH!
kit
I saw Elvis. He sat between me and Bigfoot on the UFO.

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