Re: Modeless dialog box in a thread

From:

=?Utf-8?B?QXJtYW4gU2FoYWt5YW4=?= <armancho_x@rambler.ru(donotspam)>

Newsgroups:

microsoft.public.vc.mfc

Date:

Sat, 28 Apr 2007 00:26:01 -0700

Message-ID:

<444DC856-FFE5-4B54-BE78-62ACFC2C5B97@microsoft.com>

Modeless, of course. Only do remove RunModalLoop.

--
======
Arman

"Punit Kaur" wrote:

You said I made the dialog modal. I need to create a modeless dialog. What
should I change there?

"Arman Sahakyan" wrote:

Hi,

see below...

"Punit Kaur" 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;

--------------------------------
And where do you delete pdlg? You should have CDialog::PostNcDestroy method
overriden which deletes itself; the following statement should be there;
delete this;
--------------------------------

        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();
                               }
   }

--------------------------------
Why CWnd::RunModalLoop? You've already created the dlg as modal. So remove
that line.
And how you close the dialog? You should have overriden CDialog::OnOK and
CDialog::OnCancel and call DestroyWindow() from there. Also remove the base
class overrides.
--------------------------------

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;
}

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

--------------------------------
Not the all. The caller should wait until the worker thread exits. So after
the SetEvent
there should be a line of WaitForSingleObject( hThread ..).
This means that you should have remembered the CWinThread* value when calling
AfxBeginThread.

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

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.

Thank you.

And the most interesting part. Why a worker thread at all? The same task can
be accomlished by timers (WM_TIMER). The timer would be triggered each given
amount of time and in the WM_TIMER handler function you would do the disk
checkup job. Make it easy!

--
======
Arman