Javascript stop drag event for panorama photos

I've built a simple panorama photo viewer in jquery, see live example here: http://alafiariver.org/alafia/vi开发者_如何学Pythonew/aldermans-ford

How can I prevent this from being dragged too far? These photos vary in width, so the solution needs to be dynamic.

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You can use containment property to restrict movement of image. See live example here.