JavaScript: Container with draggable. Constrain draggable to a circle shape, in container.

Question

Hey guys,

I'm looking for a simple solution to place a draggable element inside of a box container. When the user begins to interact with the draggable, the draggable element should remain constrained to a circular shape, within the container.

At a complete loss as to how I should accomplish this.

Thank you! :-)

Additional:

• Box container would be 100 pixels wide and tall
• Draggable would be 20 pixels wide and tall
• http://tool-man.org/examples/dragging.html This is on the TODO list, but of course this site is no longer maintained