import greenfoot.*;  // (World, Actor, GreenfootImage, Greenfoot and MouseInfo)  
import java.awt.Color;  
  
/** 
 * A simple counter with graphical representation as an actor on screen. 
 *  
 * @author mik 
 * @version 1.0 
 */  
public class Counter extends Actor  
{  
    private static final Color transparent = new Color(0,0,0,0);  
    private GreenfootImage background;  
    private int value;  
    private int target;  
    /** 
     * Create a new counter, initialised to 0. 
     */  
    public Counter()  
    {  
        background = getImage();  // get image from class  
        value = 0;  
        target = 0;  
        updateImage();  
    }  
    /** 
     * Animate the display to count up (or down) to the current target value. 
     */  
    public void act()   
    {  
        if (value < target) {  
            value++;  
            updateImage();  
        }  
        else if (value > target) {  
            value--;  
            updateImage();  
        }  
    }  
    /** 
     * Add a new score to the current counter value. 
     */  
    public void add(int score)  
    {  
        target += score;  
    }  
  
    /** 
     * Return the current counter value. 
     */  
    public int getValue()  
    {  
        return value;  
    }  
  
    /** 
     * Set a new counter value. 
     */  
    public void setValue(int newValue)  
    {  
        target = newValue;  
        value = newValue;  
        updateImage();  
    }  

    /** 
     * Update the image on screen to show the current value. 
     */  
    private void updateImage()  
    {  
        GreenfootImage image = new GreenfootImage(background);  
        GreenfootImage text = new GreenfootImage("" + value, 22, Color.BLACK, transparent);  
        image.drawImage(text, (image.getWidth()-text.getWidth())/2,   
                        (image.getHeight()-text.getHeight())/2);  
        setImage(image);  
    }  
}