How to zoom gradually around the mouse pointer..??

Hi there,

I need to implement zooming effect in such a way that when user clicks on the screen, the window will zoom in or out slowly, bounding a small region (square or rectangle) around the mouse pointer…

I need in a similar way as it is implemented in Google Earth… In google earth, a small slider is kept to do so… I dont need a slider, just on mouse click, it should zoom…

Waiting for replies and suggestions…

Thanks in advance

Regards
Rakesh Patil