Urgent: problems using OnIdle() function

I am using the OnIdle function following the Help instructions. I use the override version in my App class like this:


BOOL CMyApp::OnIdle(LONG lCount)
{
if(CWinApp::OnIdle(lCount))
return TRUE;

if(!m_bReceptionOK ) {
if(GetTickCount() - m_dwInitOp > COMMTMOUT) {
TRACE("Timeout occured\n");
return FALSE;
}
return TRUE;
}

return FALSE;
}



I use this function to see if a timeout occured in a serial communication. But the verification is only executed when there are messages in the application queue, like mouse messages. If a put a TRACE after the CwinApp::OnIdle call I note that lCount is always 1.

If a timeout occurs the TRACE is executed only when I move the mouse, for example. What am I doing wrong? The problem is the GetTickCount() function?

Please help me soon.

Thanks,

Celso Aquino

I'm not sure I'd use OnIdle() for communications timing...using an internal Timer would be much more reliable.

Cheers!
Humble Programmer
,,,^..^,,,

[Josh Handley]

If you always return TRUE from OnIdle() then OnIdle will continue to be called. Once you return FALSE from OnIdle() then OnIdle() will stop being called until there is a mouse or keyboard event. To see how this works you can look at the source code for CWinThread()::Run() in THRDCORE.cpp:


// main running routine until thread exits
int CWinThread::Run()
{
ASSERT_VALID(this);

// for tracking the idle time state
BOOL bIdle = TRUE;
LONG lIdleCount = 0;

// acquire and dispatch messages until a WM_QUIT message is received.
for (;
{
// phase1: check to see if we can do idle work
while (bIdle &&
!::PeekMessage(&m_msgCur, NULL, NULL, NULL, PM_NOREMOVE))
{
// call OnIdle while in bIdle state
if (!OnIdle(lIdleCount++))
bIdle = FALSE; // assume "no idle" state
}

// phase2: pump messages while available
do
{
// pump message, but quit on WM_QUIT
if (!PumpMessage())
return ExitInstance();

// reset "no idle" state after pumping "normal" message
if (IsIdleMessage(&m_msgCur))
{
bIdle = TRUE;
lIdleCount = 0;
}

} while (::PeekMessage(&m_msgCur, NULL, NULL, NULL, PM_NOREMOVE));
}

ASSERT(FALSE); // not reachable
}




In section one once OnIdle returns false bIdle is set to false and is only set to true again if a there is a message in the queue that causes IsIdleMessage() to return true.

Josh