Thread: Trouble with animation using Sleep

Okay, this is a function which is supposed to read through a list of transformations, and step through each one, with a delay of pauseTime. TransformPolygon() handles the transformations.

Actually drawing the polygon is done in WM_PAINT, and I haven't had any other problems with using InvalidateRect like this to do so.

When I test this, what happens is I have a delay (the delay is the number of transformations x pauseTime). At the end of the delay, the polygon appears where it should at the end of the animation. However, I don't see any of the intermediate steps of the animation, just the end.

I would really appreciate any insight on how to make this work. I am using DevC.

Code:

void PlayMoves (int pauseTime, HWND hWnd)
{
 int i;

 for (i = 0; i < MoveIndex; i++)
 {
  TransformPolygon();

  InvalidateRect (hWnd, NULL, TRUE);

  Sleep(pauseTime);
 }
return;
}

You could use GetTickCount() and a while loop. This would keep the progam running and allow the screen updates.

I figured out the problem. I tried using GetTickCount, but pretty much the same thing was happening. Apparantly, when using the GDI for animation like this, you need to use WindowUpdate(hWnd) to force the window to redraw itself. InvalidateRect() just tells the window to update itself ... once it's not doing anything else.

>>>
InvalidateRect() just tells the window to update itself ... once it's not doing anything else.
<<<

InvalidateRect() flags an area of the screen object that is now invalid and needs to be redrawn. The redraw occurs when the next WM_PAINT message is processed. You are in a tight loop, therefore the WM_PAINT is not received, therefore your accumulated invalidated rectangles are not processed.

If you are considering doing this, then you have a design fault! Sleep() is a blocking call, if you can specify an infinite wait, (I've never tried that, can't think of any use for it), then I would suggest your thread will be blocked infinitely.

What are you trying to do??? Sounds intruiging!!!!