01.import java.io.IOException;  
02.  
03.import javax.microedition.lcdui.Canvas;  
04.import javax.microedition.lcdui.Graphics;  
05.import javax.microedition.lcdui.Image;  
06.  
07.//ShadowCanvas.java   
08./**  
09. * @author boolean liuhao137310@163.com:  
10. * @version 创建时间：2009-2-7 下午02:01:27  
11. * @TODO 图片的渐变效果 在第一张图片的基础上渐变出第二张图片 
12. */  
13.class ShadowCanvas extends Canvas implements Runnable {   
14.    int w, h;   
15.  
16.    /**原始图片*/   
17.    Image img2;  
18.      
19.    /**渐变图片*/  
20.    Image srcImage;  
21.  
22.    // 原始图片的像素数组    
23.    int[] srcRgbImage;   
24.  
25.    // 渐变图片的像素数组    
26.    int[] shadowRgbImage;   
27.  
28.    int imgWidth, imgHeight;   
29.  
30.    int count;   
31.  
32.    /**原始图片只画一次即可 此变量记录是否是第一次画原始图片*/  
33.    private boolean first = true;  
34.      
35.    public ShadowCanvas() {   
36.        w = this.getWidth();   
37.        h = this.getHeight();   
38.        try {   
39.            srcImage = Image.createImage("/logoBg.png");   
40.            img2 = Image.createImage("/test_bg.png");  
41.        } catch (IOException e) {   
42.            e.printStackTrace();   
43.        }   
44.        imgWidth = srcImage.getWidth();   
45.        imgHeight = srcImage.getHeight();   
46.        // 制造原始图片的像素数组，用一个int来代表每一个像素,按位表示方式是:0xAARRGGBB    
47.        srcRgbImage = new int[imgWidth * imgHeight];   
48.        // 获取原始图片的所有像素，参见MIDP APPI文档    
49.        srcImage.getRGB(srcRgbImage, 0, imgWidth, 0, 0, imgWidth, imgHeight);   
50.  
51.        shadowRgbImage = new int[srcRgbImage.length];   
52.  
53.        System.arraycopy(srcRgbImage, 0, shadowRgbImage, 0,   
54.                shadowRgbImage.length);   
55.  
56.        // 渐变图片的所有像素一开始都是全透明的    
57.        for (int i = 0; i < shadowRgbImage.length; i++) {   
58.            shadowRgbImage[i] &= 0x00ffffff;   
59.        }   
60.  
61.        new Thread(this).start();   
62.  
63.    }   
64.  
65.    public void paint(Graphics g) {   
66.//        g.setColor(0, 0, 0);    
67.//        g.fillRect(0, 0, w, h);    
68.        if(first){  
69.            g.drawImage(img2, 0, 0, 0);  
70.            first = false;  
71.        }  
72.        // 绘制渐变图片    
73.        g.drawRGB(shadowRgbImage, 0, imgWidth, (w - imgWidth) / 2,   
74.                (h - imgHeight) / 2, imgWidth, imgHeight, true);   
75.  
76.        g.setColor(0, 255, 0);   
77.        g.drawString("count=" + count, w / 2, 30, Graphics.HCENTER   
78.                | Graphics.TOP);   
79.    }   
80.  
81.    public void run() {   
82.        while (true) {   
83.  
84.            boolean changed = false;   
85.            // 改变渐变图片的每一个像素    
86.            for (int i = 0; i < shadowRgbImage.length; i++) {   
87.                // 获取渐变图片的某一像素的alpha值    
88.                int alpha = (shadowRgbImage[i] & 0xff000000) >>> 24;   
89.                // 原始图片的对应像素的alpha值    
90.                int oldAlpha = (srcRgbImage[i] & 0xff000000) >>> 24;   
91.  
92.                if (alpha < oldAlpha) {   
93.                    // alpha值++  写的太精妙了 把移位用到了极致   
94.                    shadowRgbImage[i] = ((alpha + 1) << 24)   
95.                            | (shadowRgbImage[i] & 0x00ffffff);   
96.                    changed = true;   
97.                }   
98.            }   
99.  
100.            try {   
101.                Thread.sleep(10);   
102.            } catch (InterruptedException e) {   
103.                e.printStackTrace();   
104.            }   
105.            count ++;   
106.            repaint();   
107.            // 当所有像素的alpha值都达到原始值后,线程运行结束    
108.            if (!changed) {   
109.                System.out.println("over");   
110.                break;   
111.            }   
112.        }   
113.  
114.    }   
115.  
116.}