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// MyComboBox.cpp : implementation file 
// 
 
#include "stdafx.h" 
#include "ComboWidthDemo.h" 
#include "MyComboBox.h" 
 
#ifdef _DEBUG 
#define new DEBUG_NEW 
#undef THIS_FILE 
static char THIS_FILE[] = __FILE__; 
#endif 
 
///////////////////////////////////////////////////////////////////////////// 
// CMyComboBox 
 
CMyComboBox::CMyComboBox() 
{ 
} 
 
CMyComboBox::~CMyComboBox() 
{ 
} 
 
///////////////////////////////////////////////////////////////////////////// 
// Implementation 
 
void CMyComboBox::RecalcDropWidth() 
{ 
    // Reset the dropped width 
    int nNumEntries = GetCount(); 
    int nWidth = 0; 
    CString str; 
 
    CClientDC dc(this); 
    int nSave = dc.SaveDC(); 
    dc.SelectObject(GetFont()); 
 
    int nScrollWidth = ::GetSystemMetrics(SM_CXVSCROLL); 
    for (int i = 0; i < nNumEntries; i++) 
    { 
        GetLBText(i, str); 
        int nLength = dc.GetTextExtent(str).cx + nScrollWidth; 
        nWidth = max(nWidth, nLength); 
    } 
     
    // Add margin space to the calculations 
    nWidth += dc.GetTextExtent("0").cx; 
 
    dc.RestoreDC(nSave); 
    SetDroppedWidth(nWidth); 
} 
 
BEGIN_MESSAGE_MAP(CMyComboBox, CComboBox) 
	//{{AFX_MSG_MAP(CMyComboBox) 
	ON_CONTROL_REFLECT(CBN_DROPDOWN, OnDropdown) 
	//}}AFX_MSG_MAP 
END_MESSAGE_MAP() 
 
///////////////////////////////////////////////////////////////////////////// 
// CMyComboBox message handlers 
 
void CMyComboBox::OnDropdown()  
{ 
    RecalcDropWidth(); 
}