Processing System Messages

Environment: VC6

The Requirement

I needed to run a loop in a modal dialog box, but found that although the UpdateWindow() function updated the window (and did not leave me with a White Box on the screen), the buttons onscreen were unresponsive. I searched the Internet and found articles on how to open a dialog in another thread and to keep monitoring the secondary dialog, but was not happy with the solution.

The Solution

I finally came up with a solution to process the dialog box's messages in a function within the dialog box itself. It works great.

My solution consists of adding a function to the existing dialog class and calling it to process the messages.

  BOOL CMyDialog::ProcessDialogMessages()
  {
    Sleep(0);                                  // Yield to other
                                               // system processes

    // Process the message queue
    MSG dlgMsg;
    if (::PeekMessage (&dlgMsg, NULL, 0, 0, PM_NOREMOVE))
                                               // If there are
                                               // pending messages
    {
       if (!AfxGetApp ()->PumpMessage ()) {    // Allow them to be
                                               // processed
          ::PostQuitMessage (0);               // When no more
                                               // messages exist,
                                               // return WM_QUIT
                                               // should return 0
          return TRUE;                         // Return the caller,
                                               // indicating that
                                               // we just processed
                                               // a Message and that
                                               // there may be more
    }
  }

   // Simulate idle processing.
   LONG lIdle = 0;
   while (AfxGetApp ()->OnIdle (lIdle++));
     return FALSE;                             // Return to Caller,
                                               // saying that we
                                               // did not process
                                               // any messages
  }

Downloads

Download demo project - 4 Kb
Download source - 26 Kb


Comments

  • Fibers

    Posted by Legacy on 07/23/2003 12:00am

    Originally posted by: John

    If you don't want to use threads in your program, you could also try using fibers. Fibers can be scheduled within one thread according to your own algorithm, suiting a program like this quite well. See Jeffrey Richter's "Programming Applications for Microsoft Winodws" (5th Ed.) or MSDN for more information.

    Reply
Leave a Comment
  • Your email address will not be published. All fields are required.

Top White Papers and Webcasts

  • With 81% of employees using their phones at work, companies have stopped asking: "Is corporate data leaking from personal devices?" and started asking: "How do we effectively prevent corporate data from leaking from personal devices?" The answer has not been simple. ZixOne raises the bar on BYOD security by not allowing email data to reside on the device. In addition, Zix allows employees to maintain complete control of their personal device, therefore satisfying privacy demands of valued employees and the …

  • Flash technology is becoming more prominent in the storage industry. Offering superior speed and reliability when compared to traditional hard disk drives – flash storage is a flexible and increasingly cost-effective technology that can be used to optimize enterprise storage environments. This ebook explores the many uses and benefits of flash storage technology in the enterprise. Check it out to discover and learn all you need to: Optimize storage performance Leverage server flash as storage cache …

Most Popular Programming Stories

More for Developers

Latest Developer Headlines

RSS Feeds