收集了几个图像缩放函数，可能实现的方式很多，感觉这几个还是不错的，分享下
说明：以下函数都是基于MIDP2.0的，缩放后保留透明色。
代码1，resizeImage函数
收集了几个图像缩放函数，可能实现的方式很多，感觉这几个还是不错的，分享下说明：以下函数都是基于MIDP2.0的，缩放后保留透明色。
代码1，resizeImage函数
1 public static Image resizeImage(Image src, int destW, int destH) {
2 int srcW = src.getWidth();
3 int srcH = src.getHeight();
4 // create pixel arrays
5 int[] destPixels = new int[destW * destH]; // array to hold destination
6 // pixels
7 int[] srcPixels = new int[srcW * srcH]; // array with source's pixels
8 src.getRGB(srcPixels, 0, srcW, 0, 0, srcW, srcH);
9 // simple point smapled resizing
10 // loop through the destination pixels, find the matching pixel on
11 // the source and use that
12 for (int destY = 0; destY < destH; ++destY) {
13 for (int destX = 0; destX < destW; ++destX) {
14 int srcX = (destX * srcW) / destW;
15 int srcY = (destY * srcH) / destH;
16 destPixels[destX + destY * destW] = srcPixels[srcX + srcY * srcW];
17 }
18 }
19 // return a new image created from the destination pixel buffer
20 return Image.createRGBImage(destPixels, destW, destH, true);
21 }
代码2，ZoomImage函数
1 public static Image ZoomImage(Image src, int desW, int desH) {
2 Image desImg = null;
3 int srcW = src.getWidth(); // 原始图像宽
4 int srcH = src.getHeight(); // 原始图像高
5 int[] srcBuf = new int[srcW * srcH]; // 原始图片像素信息缓存
6 src.getRGB(srcBuf, 0, srcW, 0, 0, srcW, srcH);
7 // 计算插值表
8 int[] tabY = new int[desH];
9 int[] tabX = new int[desW];
10 int sb = 0;
11 int db = 0;
12 int tems = 0;
13 int temd = 0;
14 int distance = srcH > desH ? srcH : desH;
15 for (int i = 0; i <= distance; i++) { /* 垂直方向 */
16 tabY[db] = sb;
17 tems += srcH;
18 temd += desH;
19 if (tems > distance) {
20 tems -= distance;
21 sb++;
22 }
23 if (temd > distance) {
24 temd -= distance;
25 db++;
26 }
27 }
28 sb = 0;
29 db = 0;
30 tems = 0;
31 temd = 0;
32 distance = srcW > desW ? srcW : desW;
33 for (int i = 0; i <= distance; i++) { /* 水平方向 */
34 tabX[db] = (short) sb;
35 tems += srcW;
36 temd += desW;
37 if (tems > distance) {
38 tems -= distance;
39 sb++;
40 }
41 if (temd > distance) {
42 temd -= distance;
43 db++;
44 }
45 }
46 // 生成放大缩小后图形像素buf
47 int[] desBuf = new int[desW * desH];
48 int dx = 0;
49 int dy = 0;
50 int sy = 0;
51 int oldy = -1;
52 for (int i = 0; i < desH; i++) {
53 if (oldy == tabY[i]) {
54 System.arraycopy(desBuf, dy - desW, desBuf, dy, desW);
55 } else {
56 dx = 0;
57 for (int j = 0; j < desW; j++) {
58 desBuf[dy + dx] = srcBuf[sy + tabX[j]];
59 dx++;
60 }
61 sy += (tabY[i] - oldy) * srcW;
62 }
63 oldy = tabY[i];
64 dy += desW;
65 }
66 // 生成图片
67 desImg = Image.createRGBImage(desBuf, desW, desH, true);
68 return desImg;
69 }
代码3
1 public static Image scaleImage(Image original, int newWidth, int newHeight) {
2 int[] rawInput = new int[original.getHeight() * original.getWidth()];
3 original.getRGB(rawInput, 0, original.getWidth(), 0, 0, original.getWidth(), original.getHeight());
4 int[] rawOutput = new int[newWidth * newHeight];
5 // YD compensates for the x loop by subtracting the width back out
6 int YD = (original.getHeight() / newHeight) * original.getWidth() - original.getWidth();
7 int YR = original.getHeight() % newHeight;
8 int XD = original.getWidth() / newWidth;
9 int XR = original.getWidth() % newWidth;
10 int outOffset = 0;
11 int inOffset = 0;
12 for (int y = newHeight, YE = 0; y > 0; y--) {
13 for (int x = newWidth, XE = 0; x > 0; x--) {
14 rawOutput[outOffset++] = rawInput[inOffset];
15 inOffset += XD;
16 XE += XR;
17 if (XE >= newWidth) {
18 XE -= newWidth;
19 inOffset++;
20 }
21 }
22 inOffset += YD;
23 YE += YR;
24 if (YE >= newHeight) {
25 YE -= newHeight;
26 inOffset += original.getWidth();
27 }
28 }
29 return Image.createRGBImage(rawOutput, newWidth, newHeight, true);
30 }
我将100*100的图片放到到200*200后对比了一下，ZoomImage生成的图片和另外两个函数生成的图像有点区别，感觉ZoomImage效果好点。再放大点就就基本一样了，看不出区别了。
代码4
1 /*图像变换*/
2 public Image scaleImage(Image src,int scales1,int scales2)
3 {
4 return transImage(src,src.getWidth()*scales1/scales2,src.getHeight()*scales1/scales2);
5 }
6 public Image transImage(Image src, int w, int h)
7 {
8 int srcW = src.getWidth();
9 int srcH = src.getHeight();
10 int dstW=w,dstH=h;
11 Image tmp = Image.createImage(dstW, srcH);
12 Graphics g = tmp.getGraphics();
13 int scale=16;
14 int delta = (srcW << scale) / dstW;//扫描长度
15 int pos = delta / 2;//扫描位置
16 for (int x = 0; x < dstW; x++)
17 {
18 g.setClip(x, 0, 1, srcH);
19 g.drawImage(src, x - (pos >> scale), 0, Graphics.LEFT | Graphics.TOP);
20 pos += delta;
21 }
22 Image dst = Image.createImage( dstW, dstH);
23 g = dst.getGraphics();
24 delta = (srcH << scale) / dstH;
25 pos = delta / 2;
26 for (int y = 0; y < dstH; y++)
27 {
28 g.setClip(0,y, dstW, 1);
29 g.drawImage(tmp, 0, y - (pos >> scale), Graphics.LEFT | Graphics.TOP);
30 pos += delta;
31 }
32 return dst;
33 }
34
用法举例：
1.将1张图片pic转换成176*208的图,pic=transImage(pic,176,208);
2.将1张图片pic转成原来的两倍大，pic=scaleImage(pci,2,1);
3.将一张图片pic转成原来的三分之二，pic=scaleImage(pic,2,3)
代码5，
1 public static final Image scale(Image srcImage, int newW, int newH) {
2 int srcW = srcImage.getWidth();
3 int srcH = srcImage.getHeight();
4 //先做水平方向上的伸缩变换
5 Image tmp = Image.createImage(newW, srcH);
6 Graphics g = tmp.getGraphics();
7 for (int x = 0; x < newW; x++) {
8 g.setClip(x, 0, 1, srcH); //按比例放缩
9 g.drawImage(srcImage, x - x * srcW / newW, 0, Graphics.LEFT | Graphics.TOP);
10 }
11 //再做垂直方向上的伸缩变换
12 Image dst = Image.createImage(newW, newH);
13 g = dst.getGraphics();
14 for (int y = 0; y < newH; y++) {
15 g.setClip(0, y, newW, 1); //按比例放缩
16 g.drawImage(tmp, 0, y - y * srcH / newH, Graphics.LEFT | Graphics.TOP);
17 }
18 return dst;
19 }
以上内容转载自：http://blog.csdn.net/pjw100/archive/2009/11/26/4876053.aspx
