imageutil.java

<j2me 开发精解> 詹建光著 里所有的源码。对J2me的开发相当有帮助

package com.j2medev.ch8.mmapi;

import javax.microedition.lcdui.*;

public class ImageUtil {
    
    //创建缩略图
    public static Image createThumbnail(Image image,int width) {
        int sourceWidth = image.getWidth();
        int sourceHeight = image.getHeight();

        int thumbWidth = width;
        int thumbHeight = -1;
        
        if (thumbHeight == -1)
            thumbHeight = thumbWidth * sourceHeight / sourceWidth;
        
        Image thumb = Image.createImage(thumbWidth, thumbHeight);
        Graphics g = thumb.getGraphics();
        
        for (int y = 0; y < thumbHeight; y++) {
            for (int x = 0; x < thumbWidth; x++) {
                g.setClip(x, y, 1, 1);
                int dx = x * sourceWidth / thumbWidth;
                int dy = y * sourceHeight / thumbHeight;
                g.drawImage(image, x - dx, y - dy, Graphics.LEFT | Graphics.TOP);
            }
        }
        Image immutableThumb = Image.createImage(thumb);
        return immutableThumb;
    }
    
    //从int[]数组转换为byte[]
    private byte[] int2byte(int[] data) {
        byte[] buffer = new byte[4*data.length];
        for(int i=0; i<data.length; i++) {
            int p = data[i];
            buffer[i*4+0] = (byte)((p & 0xff000000)>>>24);
            buffer[i*4+1] = (byte)((p & 0xff0000)>>>16);
            buffer[i*4+2] = (byte)((p & 0xff00)>>>8);
            buffer[i*4+3] = (byte)((p & 0xff));
        }
        return buffer;
    }
    //从byte[]转换为int[]
    private int[] byte2int(byte[] data) {
        int[] buffer = new int[data.length/4];
        for(int i=0; i<data.length/4; i++) {
            int a = 0xff & data[i*4+0];
            int r = 0xff & data[i*4+1];
            int g = 0xff & data[i*4+2];
            int b = 0xff & data[i*4+3];
            buffer[i] = (a << 24) | (r << 16) | (g << 8) | b;
        }
        return buffer;
    }
}