PlayField.java

//package bricks;

import java.awt.Canvas;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.Rectangle;

class PlayField extends Canvas implements Runnable {
	private final int _delay = 20;
	private Thread _game;
	private SpriteVector _sprites;
	private Rectangle _bounds;
	private Match _match;
	private Image _offImg;
	private Graphics _offGrfx;

	public PlayField(Match m) {

		_sprites = new SpriteVector();
		_match = m;
	}

	public void paint(Graphics g) {
		g.drawImage(_offImg, 0, 0, null);
	}

	public void update(Graphics g) {
		if (_offGrfx == null) {
			_offImg = createImage(getWidth(), getHeight());
			_offGrfx = _offImg.getGraphics();
		}

		_offGrfx.clearRect(0, 0, getWidth(), getHeight());
		_sprites.draw(_offGrfx);
		drawMessage(_match.getMessage());
		g.drawImage(_offImg, 0, 0, null);
	}

	public void run() {
		Thread.currentThread().setPriority(Thread.MIN_PRIORITY);
		long theStartTime = System.currentTimeMillis();
	
		while (Thread.currentThread() == _game) {
			_sprites.update();
			repaint();
			try {
				theStartTime += _delay;
				Thread.sleep(Math.max(0, theStartTime - System.currentTimeMillis()));
			} catch (InterruptedException e) {
				break;
			}
		}
	}

	public void start() {
		if (_game == null) {
			_bounds  = new Rectangle(0,0,getWidth(),getHeight());
			_game = new Thread(this);
			_game.start();
		}
	}

	void stop() {
		if (_game != null) {
			_game = null;
		}
	}

	public Match getMatch() {
		return _match;	
	}
  
	public void addSprite(Sprite s) {
		_sprites.add(s);
	}

	public void clean() {
		//_sprites.removeAll();
		_sprites.clear();//
	}

	public Sprite testCollision(Sprite s) {
		return _sprites.testCollision(s);
	}

	private void drawMessage(String msg) {
		_offGrfx.drawString(msg,getWidth()/2-20,getHeight()/2);
	}

	public Rectangle getBoundary() {
		return _bounds;
	}
}