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 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

Comments:



Comments

  • Here You Will Find The Fashion Mbt Lami In Cheap Price

    Posted by mbt shoes on 12/01/2012 07:36pm

    can help you lose weight, it has been recognized by everyone, then is worn on the feet instantly see weight loss results? Of course not, it is a process, and now a look at how products are put on the experience of MBT process it.

    Reply
  • Strange

    Posted by siavoshkc on 06/05/2010 04:16pm

    Thank you. I thought we can use GetTextExtent directly and because DC knows the font there should be no problem calculating text width.

    Reply
Leave a Comment
  • Your email address will not be published. All fields are required.

Top White Papers and Webcasts

  • New IT trends to support worker mobility -- such as VDI and BYOD -- are quickly gaining interest and adoption. But just as with any new trend, there are concerns and pitfalls to avoid. Download this paper to learn the most important considerations to keep in mind for your VDI project.

  • Data integrity and ultra-high performance dictate the success and growth of many companies. One of these companies is BridgePay Network Solutions, a recently launched and rapidly growing financial services organization that allows merchants around the world to process millions of daily credit card transactions. Due to the nature of their business, their IT team needed to strike the perfect balance between meeting regulatory-mandated data security measures with the lowest possible levels of latency and …

Most Popular Programming Stories

More for Developers

RSS Feeds

Thanks for your registration, follow us on our social networks to keep up-to-date