how to zoom in a picture in an image control by mouse selecting an area?

First, I want to load an picture to the image controls, It worked successfully.
Then,I'd like to select an area of the picture by mouse,so the selection could be zoomed in.It Failed.
after that,I may recover the original size of the picutre. It Failed.
Is there anyone who can help me on this ZOOM IN by SELECTING.
I appreciate your help very much.
Please see the attachments.

Yeah,I have already checked that example from Andy.
But it is not the one I desired.
I want to zoom in by selecting an area of the picture.
It may have something to do with Beforedragover.