DoEvents equivalent for C++?

Question

I'm new to native c++. Right now, I made it so when I press the left mouse button, it has a for loop that does InvalidateRect and draws a rectangle, and increments X by the box size each time it iterates. But, C++ is so much faster and efficient at drawing than C# that, it draws all this instantly. What I would like is for it to invalidate the rectangle, show the rectangle, wait 50ms, then continue the loop. I tried Sleep(50) but it still waits until painting is done before showing the result. I also tried PeekMessage but it did not change anything. Any help would be appreciated. Thanks

Answer 1

DoEvents basically translates as:

void DoEvents()
{
    MSG msg;

    while ( ::PeekMessage(&msg, NULL, 0, 0, PM_NOREMOVE ) )
    {
        if ( ::GetMessage(&msg, NULL, 0, 0))
        {
            ::TranslateMessage(&msg);
            :: DispatchMessage(&msg);
        }
        else
            break;
    }
}

Answer 2

I am a bit rusty in Win32 API, but the asynchronous way of doing this would be:

• Invalidate the rect
• Set a timer (see below) to send a message after 50ms
• Return to the event loop to let WM_PAINT events happen
• On receiving the timer message, move the rect, then repeat

This way integrates nicely with being event driven. I realize this is not exactly what you ask for, but I thought I'd mention it as a possible solution anyway :)

EDIT: A quick google turns up the Windows API call SetTimer which you can use to facilitate this. The message will be a WM_TIMER one.