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

  • When it comes to desktops – physical or virtual – it's all about the applications. Cloud-hosted virtual desktops are growing fast because you get local data center-class security and 24x7 access with the complete personalization and flexibility of your own desktop. Organizations make five common mistakes when it comes to planning and implementing their application management strategy. This eBook tells you what they are and how to avoid them, and offers real-life case studies on customers who didn't let …

  • The impact of a data loss event can be significant. Real-time data is essential to remaining competitive. Many companies can no longer afford to rely on a truck arriving each day to take backup tapes offsite. For most companies, a cloud backup and recovery solution will eliminate, or significantly reduce, IT resources related to the mundane task of backup and allow your resources to be redeployed to more strategic projects. The cloud - can now be comfortable for you – with 100% recovery from anywhere all …

Most Popular Programming Stories

More for Developers

Latest Developer Headlines

RSS Feeds