/**
 * CLASS: NonStopScroller
 *
 * DESCRIPTION: creates an unlimited continuously scrolling world
 */

import greenfoot.*;

public class NonStopScroller extends World
{
    // class constants
    public static final int WIDE = 800; // world width (viewport)
    public static final int HIGH = 600; // world height (viewport)
   
    // instance reference field for Scroller object
    private Scroller scroller;
   
    // creates the world that will scroll
    public NonStopScroller()
    {
        super(WIDE, HIGH, 1, false); // create an unbounded world
        GreenfootImage image = new GreenfootImage("bg.png")); // the background image
        scroller = new Scroller(this, image); // create the Scroller object
    }
   
    public void act()
    {
        scroll();
    }
   
    // performs continuous upward scrolling
    private void scroll()
    {
        int speed = 2;
        scroller.scroll(0, -speed);
    }
}

CONTINUOUS SCROLLER