Can you crop an image using a scrollviewer?

Hi,

Well i just find that hard to understand from the perspective of making it controlled by the user, they need to be able to see something so that they can see the section of the image they are selecting. In the example i mentioned originally, it looks like your using a scrollviewer when using the app.

What i am trying to do is allow a user to select any size image they like (which i have sorted) then they need to be able to somehow crop it down to a set size BUT they should be able to select what part of the image they actually what the cropped section to display... Does that make sense?

Thanks,

Jamie