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  • Priority: Medium
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Trapping a cancel button click while doing a long DAO records transfer

I have an app that allows the user to tranfer data from one database to another.  I wish To add a cancel button.  

The user is unable to click the button during the transfer process since the primary thread is busy doing the transfer work.  I can not run my DAO transfer operation in a secondary thread since DAO only runs in primary threads(or atleast thats what Microsft says, but even when I tried it I had some memory leak issue come up).

I know this issue have been solved by many application before, which was easy if you did the work in a worker thread.  However, lie I said before DAO does not run in secondary(worker) threads and so I am not sure what to do.
0
patel4694
Asked:
patel4694
1 Solution
 
prasanthCommented:
Use something like the following:

void CMyClass::OnCancel()
{
   if (m_transferring)
       m_cancelled = TRUE;
   else
       CDialog::OnCancel();
}

void CMyClass::OnDoIt()
{
    m_transferring = TRUE;
    while (!m_cancelled)
    {
        StdMsgLoop();
        TransferOneDaoRecord(); // you implement this func
    }
    m_transferring = FALSE;
}

BOOL StdMsgLoop()
{
      MSG msg;
      while (::PeekMessage(&msg, NULL, 0, 0, PM_NOREMOVE))
      {
            if (!AfxGetApp()->PumpMessage())
            {
                  ::PostQuitMessage(0);
                  return FALSE;
            }
      }
      return TRUE;
}
0
 
patel4694Author Commented:
thanks, this was very helpfull. I did not realize that messages were queued.
0

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