Re: Modeless dialog box in a thread

From:
=?Utf-8?B?UHVuaXQgS2F1cg==?= <PunitKaur@discussions.microsoft.com>
Newsgroups:
microsoft.public.vc.mfc
Date:
Wed, 2 May 2007 09:11:00 -0700
Message-ID:
<01F5A390-5D06-4D05-B873-932D66A262E7@microsoft.com>
Thank you all. I implemented OnTimer and it works flawlessly. However, to
learn how to work with threads , I shall try to implement it that way too.
Thank you once again!

"Joseph M. Newcomer" wrote:

Still wrong...see below...
On Thu, 26 Apr 2007 21:50:04 -0700, Punit Kaur <PunitKaur@discussions.microsoft.com>
wrote:

Thank you very much for your suggestions.After reading a couple of
articles, I came up with a set of steps I may have to follow in order to get
this thing work. I am completely
new to this so please bear with me.

I have a dialog based application. So this is the sequence of steps I will
follow:

1. Define the user-defined message

#define UWM_REQUEST_DISK_SPACE_WARNING (WM_APP + 1)

2. Associate this with a handler defined in the main dialogs class

//}}AFX_MSG_MAP
       ON_MESSAGE(UWM_REQUEST_DISK_SPACE_WARNING, OnCheckDiskSpace)
   END_MESSAGE_MAP()

3. Handler Declaration

   afx_msg LRESULT OnCheckDiskSpace(UINT wParam, LONG lParam);

4. Contents of the main dialog's handler which will pop up the modeless dialog

  LRESULT CMyDialogApp::OnCheckDiskSpace(UINT wParam, LONG lParam)
  {
          CDiskSpaceWarn *pdlg;
          ULARGE_INTEGER ll,pp,oo;
          pdlg = new CDiskSpaceWarn;

       GetDiskFreeSpaceEx(NULL,&ll,&pp,&oo);
       float fDiskNum= (static_cast<float>(static_cast<__int64>(oo.QuadPart
/(1024
* 1024))))/1000;

                    if(fDiskNum<20.0)
                               {

pdlg->Create(IDD_DISKSPACEWARN,AfxGetApp()->m_pMainWnd);
                                       pdlg->ShowWindow(SW_SHOW);
                                       pdlg->CenterWindow(NULL);
                                       pdlg->RunModalLoop();
                              }

****
So why do you need a worker thread at all? You can just trigger this from a WM_TIMER
handler in your main thread!

Also, you should use the classname::IDD instead of the explict IDD_ number. It reads
better.
****

  }

5. Worker thread is defined as :

   UINT DiskSpaceWarnThread(LPVOID pvoid)
{
   BOOL running = true;
   While(running)
   {
     ::PostMessage(hwnd, UWM_REQUEST_DISK_SPACE_WARNING); // Posting
message to main window

//passing hwnd as parameter, Assuming I had passed the main dialog's handle
while creating the worker thread
      switch(::WaitForSingleObject(shutdown, 3600000))
{ /* wait */
case WAIT_TIMEOUT:
break;
case WAIT_OBJECT_0:
running = FALSE;
continue;
default:
... deal with errors
} /* wait */

  return 0;
}

****
The thread now serves no useful purpose and can be eliminated. A WM_TIMER message does
everything you need to do and does not require a thread to send the notification.
****

6. HANDLE shutdown = ::CreateEvent(NULL, TRUE, FALSE, NULL);
and will use
::SetEvent(shutdown) when the app is shutting down;

I will take care of the syntax once I am clear with the steps I need to
follow.

****
Unnecessary, since the thread now does nothing useful that couldn't be handled better in
an OnTimer handler.
****

Please let me know if I am missing any piece of code. I need to add to make
it work correctly. Again, I am in very initial stages of MFC programming, so
please bear with me.

****
At this point you have too many pieces of code. Get rid of the thread, and simply call
your routine from an OnTimer handler.
                    joe
****

Thank you.


Joseph M. Newcomer [MVP]
email: newcomer@flounder.com
Web: http://www.flounder.com
MVP Tips: http://www.flounder.com/mvp_tips.htm

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