import greenfoot.*;  



| A Counter class that allows you to display a numerical value on screen.
|
| The Counter is an actor, so you will need to create it, and then add it to
| the world in Greenfoot.  If you keep a reference to the Counter then you
| can adjust its value.  Here's an example of a world class that
| displays a counter with the number of act cycles that have occurred:
|
| <pre>
| class CountingWorld
| {
|     private Counter actCounter;
|
|     Public CountingWorld()
|     {
|         super(600, 400, 1);
|         actCounter = new Counter("Act Cycles: ");
|*         addObject(actCounter, 100, 100);
 *     }
 *     
 *     public void act()
 *     {
 *         actCounter.setValue(actCounter.getValue() + 1);
 *     }
 * }
 * </pre>
 * 
 * @author Neil Brown and Michael Kölling
| @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;
    private String prefix;
    
    public Counter()
    {
        this(new String());
    }

    


| Create a new counter, initialised to 0.
|
public Counter(String prefix)
    {
        background = getImage();  
        value = 0;
        target = 0;
        this.prefix = prefix;
        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.  This will animate
| the counter over consecutive frames until it reaches the new value.
|
public void add(int score)
    {
        target += score;
    }

    


| Return the current counter value.
|
public int getValue()
    {
        return target;
    }

    


| Set a new counter value.  This will not animate the counter.
|
public void setValue(int newValue)
    {
        target = newValue;
        value = newValue;
        updateImage();
    }
    
    


| Sets a text prefix that should be displayed before
| the counter value (e.g. "Score: ").
|
*/
    public void setPrefix(String prefix)
    {
        this.prefix = prefix;
        updateImage();
    }

    /**
     * Update the image on screen to show the current value.
     */
    private void updateImage()
|
|
{
|
|
GreenfootImage image = new GreenfootImage(background);
|
|
GreenfootImage text = new GreenfootImage(prefix + value, 22, Color.BLACK, transparent);
|
|
if (text.getWidth() > image.getWidth() - 20)
|
|
{
|
|
image.scale(text.getWidth() + 20, image.getHeight());
|
|
}
|
|
image.drawImage(text, (image.getWidth()-text.getWidth())/2,
|
|
(image.getHeight()-text.getHeight())/2);
|
|
setImage(image);
|
|
}
|
|
}