收集了几个关于J2ME图片缩放的函数

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

public static Image resizeImage(Image src, int destW, int destH) {
int srcW = src.getWidth();
int srcH = src.getHeight();
// create pixel arrays
int[] destPixels = new int[destW * destH]; // array to hold destination
// pixels
int[] srcPixels = new int[srcW * srcH]; // array with source's pixels
src.getRGB(srcPixels, 0, srcW, 0, 0, srcW, srcH);
// simple point smapled resizing
// loop through the destination pixels, find the matching pixel on
// the source and use that
for (int destY = 0; destY < destH; ++destY) {
for (int destX = 0; destX < destW; ++destX) {
int srcX = (destX * srcW) / destW;
int srcY = (destY * srcH) / destH;
destPixels[destX + destY * destW] = srcPixels[srcX + srcY * srcW];
}
}
// return a new image created from the destination pixel buffer
return Image.createRGBImage(destPixels, destW, destH, true);
}

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