SHARE

How to add Horizontal Extent handling for a CListBox

Download Source Code The following code illustrates how to implement Horizonal Extent handling for a CListBox. For more information you can look at Q66370. This class implements a derived CListBox which automatically sets the horizontal extent. CListBoxEx.h // // CListBoxEx.h v1.1 // #ifndef _LISTBOX_EX_H #define _LISTBOX_EX_H #include class CListBoxEx : public CListBox { public: //virtual […]

Written By

CodeGuru Staff

Jan 24, 1999

1 minute read

CodeGuru content and product recommendations are editorially independent. We may make money when you click on links to our partners. Learn More

Download Source Code

The following code illustrates how to implement Horizonal Extent handling
for a CListBox. For more information you can look at Q66370.
This class implements a derived CListBox which automatically sets the
horizontal extent.

CListBoxEx.h

//
// CListBoxEx.h     v1.1
//

#ifndef _LISTBOX_EX_H
#define _LISTBOX_EX_H

#include

class CListBoxEx : public CListBox
{
public:
//virtual functions
virtual int AddString( LPCTSTR sString );
virtual int DeleteString( UINT nIndex );
virtual int InsertString( int nIndex, LPCTSTR lpszItem );
virtual void ResetContent();
virtual int Dir( UINT attr, LPCTSTR lpszWildCard );

private:
//helpers
LONG GetExtentForString( LPCTSTR sText );
long GetExtentForEntireControl();
};

#endif

CListBoxEx.cpp

// CListBoxEx.cpp   v1.0
//

#include "stdafx.h"
#include "listboxex.h"


//
// see Q66370 for more information
//

///////////////////////////////////////////////////////////////////////////
///////
//
//override functions
///////////////////////////////////////////////////////////////////////////
///////

int CListBoxEx::AddString(LPCTSTR lpszItem)
{

     LONG lStringExtent = GetExtentForString(lpszItem);
     if(GetHorizontalExtent() < lStringExtent)
        SetHorizontalExtent(lStringExtent);

     return CListBox::AddString(lpszItem);
}

int CListBoxEx::DeleteString( UINT nIndex )
{
     int nCountLeft=CListBox::DeleteString(nIndex);
     if (nCountLeft== LB_ERR)
         return LB_ERR;

      LONG lMaxExtent=GetExtentForEntireControl();
      SetHorizontalExtent(lMaxExtent);

      return nCountLeft;
}

int CListBoxEx::InsertString( int nIndex, LPCTSTR lpszItem )
{
      int nInsertPos=InsertString(nIndex, lpszItem);
      if (nInsertPos== LB_ERR)
           return LB_ERR;

      LONG lStringExtent=GetExtentForString(lpszItem);
      if(GetHorizontalExtent() < lStringExtent)
           SetHorizontalExtent(lStringExtent);

      return nInsertPos;
}

void CListBoxEx::ResetContent()
{
      SetHorizontalExtent(0);
      CListBox::ResetContent(); return;
}

int CListBoxEx::Dir( UINT attr, LPCTSTR lpszWildCard )
{
     int nReturn=Dir(attr, lpszWildCard );
     if (nReturn== LB_ERR || nReturn== LB_ERRSPACE)
         return nReturn;

     LONG lMaxExtent=GetExtentForEntireControl();
     SetHorizontalExtent(lMaxExtent);
     return nReturn;
}
////////////////////////////////////////////////////////////////////////////////// 
//helper functions 
////////////////////////////////////////////////////////////////////////////////// 

LONG CListBoxEx::GetExtentForString(LPCTSTR lpszItem)
{
    CDC* cdc=this->GetDC();
    CFont* font = this->GetFont();
    CFont* pOldFont;

    if (font)
     {
        pOldFont = cdc->SelectObject(font);

          TEXTMETRIC tm;
          cdc->GetTextMetrics(&tm);

          CSize size = cdc->GetTextExtent(lpszItem, lstrlen(lpszItem) );
          size.cx += tm.tmAveCharWidth;

          cdc->SelectObject(pOldFont);
          this->ReleaseDC(cdc);

          return (LONG) size.cx;
     }

     this->ReleaseDC(cdc);

     return 0L;
}

long CListBoxEx::GetExtentForEntireControl()
{
	CDC* cdc = this->GetDC();
	CFont* font = this->GetFont();
	CFont* pOldFont;
	if (font)
	{
		pOldFont = cdc->SelectObject(font);
		TEXTMETRIC tm;
		cdc->GetTextMetrics(&tm);
		CString sText;
		LONG max_cx = 0;

/****----------------C H A N G E---REY--8/29/98----------****
 ****		for(int n = 0; n<=GetCount(); n++)
 ****----------------------------------------------------****/
		for(int n = 0; n<GetCount(); n++)
/****--------------------END CHANGE----------------------****/
		{
			this->GetText(n, sText);
			if (sText == "")
				continue;
			CSize size = cdc->GetTextExtent(sText, sText.GetLength());
			size.cx += tm.tmAveCharWidth;
			if(max_cx <= size.cx)
				max_cx = size.cx;
		}
		cdc->SelectObject(pOldFont);
		this->ReleaseDC(cdc);
		return max_cx;
	}
	this->ReleaseDC(cdc);
	return 0L;
}

BUGFIX (28 June 1998): In function GetExtentForEntireControl()
changed SText = "" ro SText == "".

BUGFIX (4 Oct. 1998): In function GetExtentForEntireControl()
modify for loop statement to fix Assertion error that occurs when
you delete a string from the listbox.

Last updated: 11 November 1998