Re: Problem with MFC Thread

From:

"AliR $VC++ MVP$" <AliR@online.nospam>

Newsgroups:

microsoft.public.vc.mfc

Date:

Tue, 16 Sep 2008 10:06:20 -0500

Message-ID:

<WXPzk.460$x%.433@nlpi070.nbdc.sbc.com>

If it was me I would do it this way.

LRESULT CProgressBarExampleDlg::OnStepProgress(WPARAM,LPARAM)
{
   m_Progress.StepIt();
   return 1;
}

LRESULT CProgressBarExampleDlg::OnThreadDone(WPARAM,LPARAM)
{
   m_PauseButton.EnableWindow(FALSE);
   m_StopButton.EnableWindow(FALSE);
   m_StartButton.EnableWindow(TRUE);
   return 1;
}

void CProgressBarExampleDlg::OnBnClickedStart()
{
   m_Progress.SetRange(0,180);
   m_Progress.SetStep(1);
   m_Progress.SetPos(0);

   m_PauseButton.EnableWindow(TRUE);
   m_StopButton.EnableWindow(TRUE);
   m_StartButton.EnableWindow(FALSE);

   m_Stop = FALSE;
   m_Paused = FALSE;

   AfxBeginThread(ThreadFunction,this);
}

void CProgressBarExampleDlg::OnBnClickedPause()
{
   m_Paused = !m_Paused;

   m_PauseButton.SetWindowText(m_Paused ? _T("Resume") : _T("Pause"));
}

void CProgressBarExampleDlg::OnBnClickedStop()
{
   m_Stop = TRUE;
}

UINT __cdecl ThreadFunction(LPVOID lpParam)
{
   CProgressBarExampleDlg *pDlg = (CProgressBarExampleDlg *)lpParam;
   ASSERT(pDlg != NULL);

   int Count = 0;
   while (Count < 180 && !pDlg->m_Stop)
   {
      if (pDlg->m_Paused)
      {
         continue;
      }
      pDlg->SendMessage(WM_STEPPROGRESS);
      Sleep(10);
      Count++;
   }

   pDlg->SendMessage(WM_THREADDONE);
   return 1;
}

You can download the sample app from here:
http://www.learnstar.com/AliR/ProgressBarExample

AliR.

"Lucress Carol" <incognito.me@gmx.de> wrote in message
news:6c0c5db3-6262-4f44-9bae-78342b9d68de@e53g2000hsa.googlegroups.com...

Hi everyone,
I've created a MFC Dialog with a Progress Bar Control, a Stop Button
and a Start Buttton.The idea is to start the progress bar Control by
clicking on the Start Button and I would like to pause (Stop Button)
the process at anytime and continue it when I click on the Start
Button again.
I 'm able to stop the process of the Progress Bar but when I try to
continue the process the whole thing crash...
Here is how my code looks like:

// CProgressBarExampleDlg.h
class CProgressBarExampleDlg : public CDialog
{
public :
CProgressBarExampleDlg(CWnd* pParent = NULL);
UINT Execute(); // here should be the process of the Progress Bar
executed
static UINT WorkerThreadLauncher(LPVOID pvParam);
HANDLE m_hEndThread;
...
...
protected:
void ProcessMessage();
volatile bool m_StopThread;
CWinThread* m_Thread;
...
...
};

//CProgressBarExampleDlg.cpp

BOOL CProgressBarExampleDlg::OnInitDialog()
{
...
m_progress.SetRange(5, 100);
m_StopThread=false;
HANDLE m_hEndThread = CreateEvent(0, TRUE, FALSE, 0);
...
return TRUE;
}

void CProgressBarExampleDlg::ProcessMessage()
{
    MSG msg;

        if (::PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
{
::TranslateMessage(&msg);
::DispatchMessage(&msg);
}
}

UINT CProgressBarExampleDlg::WorkerThreadLauncher(LPVOID pvParam)
{
  CProgressBarExampleDlg* pThreadInstance=
reinterpret_cast<CProgressBarExampleDlg*>(pvParam);
  return pThreadInstance->Execute();
}

UINT CProgressBarExampleDlg::Execute()
{
int i, count;
count=0;

while (count< 180 && !m_StopThread)
{
for (i=0;i<30;i++)
{
    m_progress.SetPos(i+10);
    Sleep(10);
}
    count++;
    ProcessMessage();
}
return 0;
}

void CProgressBarExampleDlg::OnBnStart()
{
    this->m_Thread=AfxBeginThread(WorkerThreadLauncher,this);
}

void CProgressBarExampleDlg::OnBnStop()
{
     MSG msg;
      DWORD dwResult = WaitForSingleObject( m_hEndThread, 0 );

if ( dwResult =! WAIT_OBJECT_0 )
                  {
     this->m_StopThread = true;
                  }
}

I guess in the OnBnStart() function I maybe need a if-clause to start
the process again when it has been previously interrupted?

Does someone have a suggestion?
Thank you
Lucress