1     package version12;
2     /**
3      * Curso B?sico de desarrollo de Juegos en Java - Invaders
4      * 
5      * (c) 2004 Planetalia S.L. - Todos los derechos reservados. Prohibida su reproducci?n
6      * 
7      * http://www.planetalia.com
8      * 
9      */
10    
11    
12    import java.awt.Canvas;
13    import java.awt.Color;
14    import java.awt.Dimension;
15    import java.awt.Graphics;
16    import java.awt.event.WindowAdapter;
17    import java.awt.event.WindowEvent;
18    import java.awt.image.BufferStrategy;
19    import java.awt.image.BufferedImage;
20    import java.net.URL;
21    import java.util.HashMap;
22    
23    import javax.imageio.ImageIO;
24    import javax.swing.JFrame;
25    import javax.swing.JPanel;
26    
27    public class Invaders extends Canvas {
28      public static final int WIDTH = 640;
29      public static final int HEIGHT = 480;
30      public static final int SPEED = 10;
31      
32      public BufferStrategy strategy;
33      public HashMap sprites;
34      public int posX,posY,vX;

35      public long usedTime;

36      
37      public Invaders() {
38        sprites = new HashMap();
39        posX = WIDTH/2;
40        posY = HEIGHT/2;
41        vX = 2;
42      
43        JFrame ventana = new JFrame("Invaders");
44        JPanel panel = (JPanel)ventana.getContentPane();
45        setBounds(0,0,WIDTH,HEIGHT);
46        panel.setPreferredSize(new Dimension(WIDTH,HEIGHT));
47        panel.setLayout(null);
48        panel.add(this);
49        ventana.setBounds(0,0,WIDTH,HEIGHT);
50        ventana.setVisible(true);
51        ventana.addWindowListener( new WindowAdapter() {
52          public void windowClosing(WindowEvent e) {
53            System.exit(0);
54          }
55        });
56        ventana.setResizable(false);
57        createBufferStrategy(2);
58        strategy = getBufferStrategy();
59        requestFocus();
60      }
61      
62      public BufferedImage loadImage(String nombre) {
63        URL url=null;
64        try {
65          url = getClass().getClassLoader().getResource(nombre);
66          return ImageIO.read(url);
67        } catch (Exception e) {
68          System.out.println("No se pudo cargar la imagen " + nombre +" de "+url);
69          System.out.println("El error fue : "+e.getClass().getName()+" "+e.getMessage());
70          System.exit(0);
71          return null;
72        }
73      }
74      
75      public BufferedImage getSprite(String nombre) {
76        BufferedImage img = (BufferedImage)sprites.get(nombre);
77        if (img == null) {
78          img = loadImage("res/"+nombre);
79          sprites.put(nombre,img);
80        }
81        return img;
82      }
83      
84      public void paintWorld() {
85        Graphics g = strategy.getDrawGraphics();
86        g.setColor(Color.black);
87        g.fillRect(0,0,getWidth(),getHeight());
88        g.drawImage(getSprite("bicho.gif"), posX, posY,this);
89    
90        g.setColor(Color.white);

91        if (usedTime > 0)
92          g.drawString(String.valueOf(1000/usedTime)+" fps",0,HEIGHT-50);
93        else
94          g.drawString("--- fps",0,HEIGHT-50);

95        strategy.show();
96      }
97      
98    
99      
100     public void updateWorld() {
101       posX += vX;
102       if (posX < 0 || posX > WIDTH) vX = -vX;
103     }
104     
105     public void game() {

106       usedTime=1000;
107       while (isVisible()) {
108         long startTime = System.currentTimeMillis();
109         updateWorld();
110         paintWorld();
111         usedTime = System.currentTimeMillis()-startTime;

112         try { 
113            Thread.sleep(SPEED);
114         } catch (InterruptedException e) {}
115       }
116     }
117     
118     public static void main(String[] args) {
119       Invaders inv = new Invaders();
120       inv.game();
121     }
122   }
123