//========================================================================
// ImageAutoStep - add animation controls to an image viewer
//
// To build an image viewer with animation controls:
//
// Create a form that selects the image to view. For example, you might
// have elements to specify a date or location or type of image.
//
// Write a function to read the form data and display the appropriate
// image.
//
// Write a function to step the images forward or backward by a given
// number of frames. This function should update the form elements and
// call the image display function.
//
// Create a new ImageAutoStep object and pass the name of the forward and
// backward stepping function to the constructor.
//
// Add animation control buttons to your form and call the ImageAutoStep
// object's corresponding function from the button's onclick event
// handler. Avoid using submit buttons, either
//
// Finally, the onload event handler of the image's IMG tag must call the
// animation control object's nextFrame() method.
//
//
// Here's how to include the script in the viewer page:
//
//
//
//
// ...
//