How to draw something when a function costs a large time

[Golden]

i design a class only from CObject. In this class, a function costs a large time, so i want to draw something in CView or a CEdit control when this function is running. i use a OnTimer() in CView class, but it can't work. and i use a OnTimer() in Dialog class, it is wrong. How to do this?

Please if anyone can help?