In MFC CEdit control, calling setwindowtext and setsel in EN_UPDATE makes ctrl+z not working?

Question

Hi,

In MFC CEdit control, calling setwindowtext and setsel in EN_UPDATE makes ctrl+z not working?

I need to allow only 0 to 2147483647 if user typ more than this value, in EN_UPDATE I am resetting the value previously typed valid value.

If I reset the value in EN_UPDATE, the ctrl+z (undo/redo) is not working?

void CObjIdEdit::OnEnUpdate()
{
 CString szText;
    GetWindowText( OUT szText );

 // Get the number of digits in the INT_MAX.
 CString szIntMax;
 szIntMax.Format( L"%ld", INT_MAX ); // void.
 int iLength = szIntMax.GetLength();
 __int64 i64Data = _wtoi64( szText );
 int iGoodValueLength = m_szGoodValue.GetLength();

 // If the value is greater than INT_MAX(2147483647), get the number with digits  
 // of one subtracted from number of digits of INT_MAX.
 if( i64Data > INT_MAX )
 {
 // Find the caret position.
 int iStartChar = 0;
 int iEndChar = 0;
 GetSel( OUT iStartChar, OUT iEndChar ); // void.
 int nTotalLength = szText.GetLength();

 // Get good value by subtracting digits.
 if( iGoodValueLength != iLength )
 {
 // Get good value by subtracting digits.
 CString szValue = szText;
 //int nTotalLength = szText.GetLength();
 int iDiff = ( nTotalLength - ( iLength - 1 ) );
 int iIndex = iStartChar - iDiff - 1;
 szValue.Delete( iIndex, iDiff );
 m_szGoodValue = szValue;

 // Calculate start and end position.
 int iLenDiff = nTotalLength - iLength ;
 if( iStartChar > iLength) iStartChar -= iLenDiff;
 if( iEndChar > iLength) iEndChar -= iLenDiff;
 }

 // Set Value.
 SetSel( 0, -1, true );
 ReplaceSel( m_szGoodValue, true);
 //SetWindowText( m_szGoodValue ); // void.

 // Restore the caret.
 if( iStartChar > iLength ) iStartChar = iLength;
 if( iEndChar > iLength ) iEndChar = iLength;
 SetSel( iStartChar - 1, iEndChar - 1, true ); // void.
 }
 else
 {
 // Copy the text.
  m_szGoodValue = szText;
 }
}

How to resolve this issue?

Thanks

Answer 1

Calling SetWindowText clears the edit control undo flag. Use ReplaceSel instead but be careful of reentering the event handler and stack overflows.

Answer 2

Take a look at this.

In CMyEdit header -

    afx_msg void OnEnUpdate();
    CString m_strOld;
    bool m_bEnter{ true };

In CMyEdit cpp file -

void CMyEdit::OnEnUpdate()
{
    ASSERT((GetStyle() & ES_NUMBER) == ES_NUMBER);
    if (m_bEnter)
    {
        CString str;
        GetWindowText(str);
        LPTSTR ptr{};
        ULONG val = _tcstoul(str, &ptr, 10);
        if (val > 0 && val <= (ULONG) MAXINT)
        {
            m_strOld = str;
        }
        else
        {
            m_bEnter = !m_bEnter;
            SetSel(0, -1);
            ReplaceSel(m_strOld, TRUE);
            m_bEnter = !m_bEnter;
        }
    }
}