Draggable UI Within Another UI.

I wanted to try and see if it was possible to have a UI Image as a child object of another UI Image, and drag the child Image only inside of the parent bounds? I know it can be done with Screen Width etc, but the methods ive tried related to these same functions have proved non beneficial. Has any one else been able to accomplish this? The idea im using is to create a masked image that you move around a Profile picture that when in the desired position, you can take a screen shot of the area you want to be your Profile Pic. The mask ans stuff works and im able to drag the Image but i cant set the bounds to only stay within the Dimensions of the Profile pic.

I may not quite understand what you are asking. But do you mean something like this?

Yeah ive used his package but his doesnt have a boundary. You just drag the box all around the screen.