The code below demonstrates dragging an image that is larger than the stage. Tap or click at a point to add a circle there. The circles and image can be dragged as a group. The group is bound inside the stage so that the entire stage is always occupied by some portion of the image.
The result works smoothly in mobile Safari and Chrome on the PC. Pan and zoom on a Motorola Xoom tablet with Android 4 (Ice Cream Sandwich) is very jerky.
Enjoy the Crab Nebula!