C / C++ / MFC

20-Feb-07 5:05

Hi,
I've created an MDI application that has a tool bar with buttons which open dialog boxes when clicked.
One Dialog Box class in this application needs a timer.
After reading about CWnd::SetTimer():

UINT_PTR SetTimer(UINT_PTR nIDEvent,UINT uElapse,<br />
TIMERPROC lpTimerFunc);

I've done the following:

<br />
test.h:<br />
class test : public CDialog<br />
{<br />
...<br />
afx_msg void OnStart();<br />
...<br />
};<br />
void CALLBACK EXPORT TimerProc(<br />
HWND hWnd, // handle of CWnd that called SetTimer<br />
UINT nMsg, // WM_TIMER<br />
UINT nIDEvent // timer identification<br />
DWORD dwTime // system time<br />
);<br />
=================================<br />
test.cpp<br />
BEGIN_MESSAGE_MAP(test, CDialog)<br />
     ON_WM_TIMER()<br />
END_MESSAGE_MAP()<br />
<br />
void test::OnStart()<br />
{<br />
   ...<br />
   int timer;<br />
   ...<br />
   timer = SetTimer(1,1000,TimerProc); // 1000 milisecond timer<br />
   int i = 0;<br />
   while(i<999999999)<br />
   {<br />
      i++; //TIMER SHOULD TIMEOUT IN HERE take about 7sec.<br />
   }<br />
   KillTimer(timer);// <-COMES TO THIS POINT<br />
   ...<br />
}<br />
<br />
void CALLBACK TimerProc(<br />
HWND hWnd, // handle of CWnd that called SetTimer<br />
UINT nMsg, // WM_TIMER<br />
UINT nIDEvent // timer identification<br />
DWORD dwTime // system time<br />
)<br />
{<br />
   MessageBeep(0xFFFFFFFF);   // Beep<br />
   MSMPlaybackDlg* pbDlg = NULL;<br />
   pbDlg->OnButtonHddPause();<br />
   KillTimer(hWnd, pbDlg->timer);<br />
}<br />

the problem is that it doesn't call the TimerProc. It's as if it doesn't timeout after 1000miliseconds.

does anyone know what i'm doing wrong? Confused | :confused:

thanks,

Kitty5

22491720-Feb-07 5:25

224917

20-Feb-07 5:25

It looks like your while loop does not give the main window thread any chance to process its message queue. And once the while loop is exit you also kill the timer immediately.

suhredayan

kitty520-Feb-07 5:35

20-Feb-07 5:35

suhredayan® wrote:
It looks like your while loop does not give the main window thread any chance to process its message queue.

Actually the code is and I also tried the following:

<br />
int timer;<br />
int i;<br />
MSG msg;<br />
HWND hwndTimer = (HWND)this;<br />
while(something)<br />
{<br />
   timer = SetTimer(1,1000,TimerProc);<br />
   i = 0;<br />
   while(i<999999999)<br />
   {<br />
      GetMessage(&msg, NULL, 0, 0);<br />
      if(msg.message == WM_TIMER)<br />
          msg.hwnd = hwndTimer; // <-It does come here so the timer does  <br />
                                   get to 1000<br />
      TranslateMessage(&msg);<br />
      DispatchMessage(&msg);<br />
      i++;<br />
   }<br />
   KillTimer(timer); <br />
}<br />

but it still doesn't execute the TimerProc()

Kitty5

22491720-Feb-07 6:07

224917

20-Feb-07 6:07

kitty5 wrote:
msg.hwnd = hwndTimer;

Why do you need above line ? The WM_TIMER message should have a NULL hWnd for DispatchMessage to invoke the callback.

suhredayan

kitty520-Feb-07 9:02

20-Feb-07 9:02

unfortunatly i don't see the WM_TIMER invoke the callback with or without the

suhredayan® wrote:
kitty5 wrote:
msg.hwnd = hwndTimer;

grrr....

This should be such a simple task...
call SetTimer(1, 1000, TimerProc); is 1000milliseconds pass before the task completes "Pause"
if it does complete then disable timer. until it loops back up to the top....

Kitty5

led mike20-Feb-07 5:49

led mike

20-Feb-07 5:49

Take a look at the TimerQueue [^]library.

led mike

kitty520-Feb-07 6:08

20-Feb-07 6:08

Yes, i've tried that also. but I get an Assert error in the wincore.h.
I wanted to start a timer before i started doing something. if 1sec has passed then PAUSE. if complete before 1sec then stop timer.

<br />
HANDLE m_TimerHandle = INVALID_HANDLE_VALUE;<br />
<br />
void test::OnButtonStart<br />
{<br />
...<br />
while(something)<br />
{<br />
   int i = 0;<br />
   ...<br />
   BOOL success = ::CreateTimerQueueTimer(&m_timerHandle, NULL, TimerProc,<br />
                                          this, 0, 1000,<br />
                                          WT_EXECUTEONLYONCE);<br />
   while(i<999999)<br />
   {<br />
      i++;<br />
   }<br />
   DeleteTimerQueueTimer(NULL, m_timerHandle, NULL);<br />
   ...<br />
}<br />
}<br />
<br />
void test::QueueTimerHandler()<br />
{<br />
   MessageBeep(0xFFFFFFFF);<br />
   DeleteTimerQueueTimer(NULL, m_timerHandle, NULL);<br />
   OnButtonPause(); //<-ASSERT Happens after this is completed (it just<br />
                      changes colors on the button)<br />
}<br />
void CALLBACK TimerProc(void *lpParam, BOOLEAN timeFired)<br />
{<br />
  test *obj = (test*) lpParam;<br />
  obj->QueueTimerHandler();<br />
}<br />

Kitty5

Re: SetTimer() &amp; TimerProc

led mike20-Feb-07 10:57

led mike

20-Feb-07 10:57

kitty5 wrote:
I get an Assert error in the wincore.h.

Probably because you need WINVER defined to be 5 or higher
here is a snippet from one of my files that uses that library

#if WINVER < 0x0500
/**
	TimerQueueTimer class implementation uses kernel objects
	that are not available before the windows 5 kernel. Place the
	following definitions in your stdafx.h file to remove this warning:

#define _WIN32_WINNT 0x0500
#define WINVER 0x0500

*/
#error TimerQueueTimer.h requires Win32 Kernel 5
#endif

led mike

Stephen Hewitt20-Feb-07 11:32

Stephen Hewitt

20-Feb-07 11:32

See here[^] for a description of what you're doing wrong and some insight on how timers work.

The following code from your post is the cause of the problem and is wrong in a few levels:

int i = 0;
while(i<999999999)
{
i++; //TIMER SHOULD TIMEOUT IN HERE take about 7sec.
}

Firstly, as the link I gave above explains, you're not dispatching messages so the timer process will not get called. Secondly, in a multitasking system busy waits should be avoided at all costs. Try code like this:

MSG m;
while (GetMessage(&m, NULL, 0, 0) )
{
	DispatchMessage(&m);
}

You will have to implement some mechanism to break out of the message loop after 7 seconds for this code to be the same as your code however. Another timer would do the trick.

Steve

Hamid Taebi20-Feb-07 17:58

Hamid Taebi

20-Feb-07 17:58

And see an article Date and Time in C++[^] about timer and date Wink | ;)

WhiteSky

CreateDirectory Question

Programm3r20-Feb-07 3:59

20-Feb-07 3:59

Hi all,

Would the CreateDirectory function throw an exception if the directory that it must create already exists? (Stupid question I know .... D'Oh! | :doh:

)

Many Thanx
Regards,

The only programmers that are better than C programmers are those who code in 1's and 0's..... Smile | :)

Programm3r

toxcct20-Feb-07 4:23

toxcct

20-Feb-07 4:23

what does the msdn say about it ?

[VisualCalc][Flags Beginner's Guide] | [Forums Guidelines][My Best Advice]

Programm3r20-Feb-07 4:25

20-Feb-07 4:25

toxcct, I have read what MS has posted on MSDN. And the only relevent information I could find was that the return value would be ERROR_ALREADY_EXISTS, but that doesn't answer my question, or does it?

The only programmers that are better than C programmers are those who code in 1's and 0's..... Smile | :)

Programm3r

toxcct20-Feb-07 4:28

toxcct

20-Feb-07 4:28

yes it does... returning a value means that it knows that case, and don't throw an exception.

moreover, know that the Win32 API is written in C, not C++, so exceptions are unknown in C.

[VisualCalc][Flags Beginner's Guide] | [Forums Guidelines][My Best Advice]

Programm3r20-Feb-07 4:30

20-Feb-07 4:30

Thank you toxcct, and thats why you are a MVP and I'm not ...

The only programmers that are better than C programmers are those who code in 1's and 0's..... Smile | :)

Programm3r

Stephen Hewitt20-Feb-07 11:36

Stephen Hewitt

20-Feb-07 11:36

toxcct wrote:
moreover, know that the Win32 API is written in C, not C++, so exceptions are unknown in C.

SEH in not a feature of standard C but that can be used in C on Microsoft systems and the OS does throw SEH exceptions at times (not in this case however).

Steve

prasad_som20-Feb-07 4:24

prasad_som

20-Feb-07 4:24

Programm3r wrote:
Would the CreateDirectory function throw an exception if the directory that it must create already exists?

No, It will return 0.
And GetLastError returns ERROR_ALREADY_EXISTS.
i.e.

BOOL bCreated = CreateDirectory(..);//Call function
if (bCreated ==FALSE )
{
  if (GetLastError() == ERROR_ALREADY_EXISTS)
{
 //this will be true
}
}

Prasad
Notifier using ATL | Operator new[],delete[][^]

Programm3r20-Feb-07 4:26