Re: timer-event in a CDocument-derived class

From:

mfc <mfcprog@googlemail.com>

Newsgroups:

microsoft.public.vc.mfc

Date:

Thu, 19 Aug 2010 12:25:15 -0700 (PDT)

Message-ID:

<d7f3127d-96c9-4d52-b466-cc1b3b6b7047@z10g2000yqb.googlegroups.com>

On 19 Aug., 20:22, Joseph M. Newcomer <newco...@flounder.com> wrote:

See by essay on how to add a timer to a CDocument class, on my MVP Tips s=

ite.

Hint: it involves creating a dummy window to handle the timer notificatio=

joe

More below...

On Thu, 19 Aug 2010 08:37:44 -0700 (PDT), mfc <mfcp...@googlemail.com> wr=

ote:

Hi,

using a SDI (single-doc-template) application, is it also possible to
generate a timer-event in a CDocument-derived class (http://
www.flounder.com/cdocumenttimer.htm)?

My default document class is:
class CMIAppDoc : public CDocument

For my serial-ports, I need a timer. Therefore I tried to implement a
second class ( CTimedDocument) derived from the CDocument. Do I have
to derived this class from my CMIAppDoc (because of the sdi
restriction to only one document)?

class CSerialWrite : public CWinThread
{
  CTimedDocument tdoc;
  CTimerWnd wnd;
  void Init(void);
};

void CSerialWrite::Init(void)
{
wnd.Start(3000, &tdoc);
}

The problem I have is that the virtual method
virtual void OnTimer(){ ASSERT(FALSE); }
failed, because it is not correct declared in my subclass?!?

class CTimedDocument : public CDocument
{

  protected:
     virtual void OnTimer(){ ASSERT(FALSE); }
};

class CSerialTimeDoc : public CTimedDocument
{
  protected:
     virtual void OnTimer();

****
Note that you cannot put an OnTimer handler in a CDocument class. This=

is because

WM_TIMER messages are only sent to windows, and a document cannot receive=

them.

You cannot override this method. For one thing, if you read the docume=

ntation of OnTimer,

you would have seen it is
afx_msg void OnTimer(UINT_PTR nIdEvent)
which means that (a) it is member of CWnd, and therefore cannot be in CDo=

cument (b) it is

not virtual, so your declaration of a virtual method is meaningless.

I note that the most critical piece of code, the piece of code where you =

set the timer,

has not been shown, so it is not clear how we are supposed to guess at wh=

at you did, or

why you would expect the OnTimer method to be called.
joe
****>};

best regards
Hans

Joseph M. Newcomer [MVP]
email: newco...@flounder.com
Web:http://www.flounder.com
MVP Tips:http://www.flounder.com/mvp_tips.htm- Zitierten Text ausblenden =

- Zitierten Text anzeigen -

thanks for your answer. I`m using your CTimerWnd class. In my thread-
class I call the CTimerWnd::Start() method. -> afx_msg OnTimer is
called and doc->OnTimer will take a look if there`s such an method in
the document subclass CSerialTimeDoc because doc is a member of
CTimedDocument. And CTimedDocument has only a virtual void OnTimer()
installed.

class CTimedDocument : public CDocument
{
   protected:
      virtual void OnTimer(){ ASSERT(FALSE); }
};

But I always get the ASSERT.

class CSerialTimeDoc : public CTimedDocument
{
   protected:
      virtual void OnTimer();
};

Here`s the start where I create the new window.

BOOL CTimerWnd::Start(UINT ms, CTimedDocument * d)
   {
    interval = ms;
    doc = d;
    return CWnd::Create(NULL, // class name, left MFC invent one
                NULL, // title, meaningless
                WS_CHILD, // child window
            // conspicuous by its absense:
                      // WS_VISIBLE
                CRect(0,0,10,10), // useless nonempty rectangle
                AfxGetMainWnd(), // attach to main window, need someplace
                IDC_STATIC); // window ID
  }

void CTimerWnd::OnTimer(UINT nIDEvent)
{
if(doc != NULL)
        doc->OnTimer(); //?!?!? virtual void
OnTimer(void) failed

CWnd::OnTimer(nIDEvent);
}

int CTimerWnd::OnCreate(LPCREATESTRUCT lpCreateStruct)
{
    if (CWnd::OnCreate(lpCreateStruct) == -1)
        return -1;

        SetTimer(IDT_TIMER, interval, NULL);
    return 0;
}

best regards
Hans