1    package net.rmi.rmiimage; 
2     
3    import java.awt.*; 
4    import java.awt.image.IndexColorModel; 
5    import java.awt.image.MemoryImageSource; 
6     
7    public 
8        class MandelbrotCanvas extends Canvas { 
9      Image image; 
10    
11     public void paint(Graphics g) { 
12       if (image == null) { 
13         image = getToolkit().createImage( 
14             new MemoryImageSource(300, 200, 
15                                   generateColorModel(), generatePixels(300, 200), 0, 300)); 
16       } 
17       g.drawImage(image, 0, 0, this); 
18     } 
19    
20     IndexColorModel generateColorModel() { 
21       byte[] r = new byte[16]; 
22       byte[] g = new byte[16]; 
23       byte[] b = new byte[16]; 
24    
25       r[0] = 0; 
26       g[0] = 0; 
27       b[0] = 0; 
28       r[1] = 0; 
29       g[1] = 0; 
30       b[1] = (byte) 192; 
31       r[2] = 0; 
32       g[2] = 0; 
33       b[2] = (byte) 255; 
34       r[3] = 0; 
35       g[3] = (byte) 192; 
36       b[3] = 0; 
37       r[4] = 0; 
38       g[4] = (byte) 255; 
39       b[4] = 0; 
40       r[5] = 0; 
41       g[5] = (byte) 192; 
42       b[5] = (byte) 192; 
43       r[6] = 0; 
44       g[6] = (byte) 255; 
45       b[6] = (byte) 255; 
46       r[7] = (byte) 192; 
47       g[7] = 0; 
48       b[7] = 0; 
49       r[8] = (byte) 255; 
50       g[8] = 0; 
51       b[8] = 0; 
52       r[9] = (byte) 192; 
53       g[9] = 0; 
54       b[9] = (byte) 192; 
55       r[10] = (byte) 255; 
56       g[10] = 0; 
57       b[10] = (byte) 255; 
58       r[11] = (byte) 192; 
59       g[11] = (byte) 192; 
60       b[11] = 0; 
61       r[12] = (byte) 255; 
62       g[12] = (byte) 255; 
63       b[12] = 0; 
64       r[14] = (byte) 80; 
65       g[14] = (byte) 80; 
66       b[14] = (byte) 80; 
67       r[14] = (byte) 192; 
68       g[14] = (byte) 192; 
69       b[14] = (byte) 192; 
70       r[15] = (byte) 255; 
71       g[15] = (byte) 255; 
72       b[15] = (byte) 255; 
73    
74       return new IndexColorModel(4, 16, r, g, b); 
75     } 
76    
77     final float xmin = -2.0f; 
78     final float xmax = 1.2f; 
79     final float ymin = -1.2f; 
80     final float ymax = 1.2f; 
81    
82     byte[] generatePixels(int w, int h) { 
83       byte[] pixels = new byte[w * h]; 
84       int pIx = 0; 
85       float[] p = new float[w]; 
86       float q = ymin; 
87       float dp = (xmax - xmin) / w; 
88       float dq = (ymax - ymin) / h; 
89    
90       p[0] = xmin; 
91       for (int i = 1; i < w; i++) { 
92         p[i] = p[i - 1] + dp; 
93       } 
94    
95       for (int r = 0; r < h; r++) { 
96         for (int c = 0; c < w; c++) { 
97           int color = 1; 
98           float x = 0.0f; 
99           float y = 0.0f; 
100          float xsqr = 0.0f; 
101          float ysqr = 0.0f; 
102          do { 
103            xsqr = x * x; 
104            ysqr = y * y; 
105            y = 2 * x * y + q; 
106            x = xsqr - ysqr + p[c]; 
107            color++; 
108          } while (color < 512 && xsqr + ysqr < 4); 
109          pixels[pIx++] = (byte) (color % 16); 
110        } 
111        q += dq; 
112      } 
113      return pixels; 
114    } 
115  } 
116