1    package bookExamples.ch26Graphics.radar; 
2     
3    import javax.swing.JComponent; 
4    import java.awt.Color; 
5    import java.awt.Container; 
6    import java.awt.Dimension; 
7    import java.awt.Graphics; 
8    import java.awt.GridLayout; 
9     
10   public class JRadar extends JComponent { 
11       private double thetaInRadians = 0; 
12       private Target targets[] = { 
13           new Target("t1", 30, 50) 
14       }; 
15    
16       JRadar(int w, int h) { 
17           setSize(w, h); 
18       } 
19    
20       public Dimension getPreferredSize() { 
21           return new Dimension(200, 200); 
22       } 
23    
24       public void paint(Graphics g) { 
25           Dimension d = getSize(); 
26           double deltaTheta = 
27                   3 * Math.PI / 180.0; 
28           int width = d.width; 
29           int height = d.height; 
30           int xc = width / 2; 
31           int yc = height / 2; 
32           g.setColor(Color.red); 
33           int r = Math.min(xc, yc); 
34           double xr = 
35                   r * Math.cos(getThetaInRadians()) + xc; 
36           double yr = 
37                   r * Math.sin(getThetaInRadians()) + yc; 
38           setThetaInRadians(getThetaInRadians() + deltaTheta); 
39           //for (int i = 0; i < getTargets().length; i++) 
40           //    getTargets()[i].draw(g); 
41           // g.setXORMode(Color.red); 
42           g.drawLine(xc, yc, (int) xr, (int) yr); 
43           g.setColor(Color.BLUE); 
44           g.drawString("target", (int) xr, (int) yr); 
45           g.setColor(Color.cyan); 
46           g.drawRect(0, 0, width - 5, height - 5); 
47           //sleep(10); 
48           repaint(); 
49       } 
50    
51       public static void sleep(long l) { 
52           try { 
53               Thread.sleep(l); 
54           } catch (InterruptedException e) { 
55               e.printStackTrace(); 
56           } 
57       } 
58    
59       public static void main(String args[]) { 
60           gui.ClosableJFrame cf = new gui.ClosableJFrame(); 
61           Container c = cf.getContentPane(); 
62           c.setBackground(Color.BLACK); 
63           for (int i = 0; i < 50; i++) 
64               c.add(new JRadar(200, 200)); 
65           c.setLayout(new GridLayout(10, 0)); 
66           cf.setSize(400, 400); 
67           cf.setVisible(true); 
68       } 
69    
70       public double getThetaInRadians() { 
71           return thetaInRadians; 
72       } 
73    
74       public void setThetaInRadians(double thetaInRadians) { 
75           this.thetaInRadians = thetaInRadians; 
76       } 
77    
78       public Target[] getTargets() { 
79           return targets; 
80       } 
81    
82       public void setTargets(Target[] targets) { 
83           this.targets = targets; 
84       } 
85   } 
86