BUG: MCIWndClass Popup Window Palette Flashes (121330)

hwndPanel = MCIWndCreate(hwndParent, hInst,
      MCIWNDF_NOAUTOSIZEMOVIE | MCIWNDF_NOMENU |
      WS_OVERLAPPED | WS_BORDER | WS_CAPTION |
      WS_SYSMENU | WS_POPUP, NULL);
   MCIWndOpen(hwndPanel, fname, 0);
   MCIWndRealize(hwndPanel, TRUE);
   SetWindowPos(hwndPanel, HWND_TOP, X, Y, 0, 0,
      SWP_NOSIZE | SWP_DRAWFRAME | SWP_SHOWWINDOW);
   MCIWndPlay(hwndPanel);
				

MORE INFORMATION

The problem described in the SYMPTOMS section occurs only with popup windows. It does not arise when the window style is WS_CHILD. When the window is a child window, the WM_QUERYNEWPALETTE messages are processed by the parent window's callback procedure instead of the MCIWndProc() procedure.

When the window involved is a popup window, you can avoid the flash by subclassing the MCIWndProc() procedure and allowing the subclassing application to process the WM_QUERYNEWPALETTE message directly by calling MCIWndRealize() with the fBkgnd flag set to TRUE. The following code demonstrates this workaround:

// MakeProcInstance() is called once in a convenient place such
// as the application's InitInstance() procedure. RealizeProc()
// is the procedure that subclasses MCIWndProc(). RealizeProc()
// will process WM_QUERYNEWPALETTE messages on behalf of
// MCIWndProc(). In the Module Definition File, list the
// RealizeProc() procedure under EXPORTS.

   lpfnRealizeProc = MakeProcInstance((FARPROC)
      RealizeProc, hinstCurrent);

// In the application's MainWndProc() under "case WM_DESTROY:",
// call FreeProcInstance().

   FreeProcInstance(lpfnRealizeProc);

// Add the next two function calls to the code shown in the
// Symptoms section just after the call to MCIWndCreate(). The
// GetWindowLong() call returns a pointer to the popup window's
// original window procedure, namely MCIWndProc(). The
// SetWindowLong() procedure specifies that the RealizeProc()
// procedure is the new window procedure for the popup window.

   lpfnOldRealizeProc = (FARPROC)GetWindowLong(hwndPanel,

      GWL_WNDPROC);

   SetWindowLong(hwndPanel, GWL_WNDPROC, (LONG)
      lpfnRealizeProc);

// The following procedure subclasses MCIWndProc(). It processes
// the WM_QUERYNEWPALETTE messages. All other messages
// are sent to MCIWndProc(), which is pointed to by the
// parameter lpfnOldRealizeProc.

long FAR PASCAL RealizeProc(HWND hwndPanel, UINT message, WPARAM
               wParam, LPARAM lParam)
{
   switch (message)
   {
      case WM_QUERYNEWPALETTE:
         return (MCIWndRealize(hwndPanel, TRUE));

      default:
          return (CallWindowProc((WNDPROC)lpfnOldRealizeProc,
            hwndPanel, message, wParam, lParam));
   }
}