[整理]收集的几个J2ME图像缩放函数

收集了一下图像缩放的函数，可能实现的方式很多，感觉这几个不错的，分享下

 

说明：以下函数都是基于MIDP2.0的，缩放后保留透明色。

 

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);
	}
	

public static Image ZoomImage(Image src, int desW, int desH) {
		Image desImg = null;
		int srcW = src.getWidth(); // 原始图像宽
		int srcH = src.getHeight(); // 原始图像高
		int[] srcBuf = new int[srcW * srcH]; // 原始图片像素信息缓存

		src.getRGB(srcBuf, 0, srcW, 0, 0, srcW, srcH);

		// 计算插值表
		int[] tabY = new int[desH];
		int[] tabX = new int[desW];

		int sb = 0;
		int db = 0;
		int tems = 0;
		int temd = 0;
		int distance = srcH > desH ? srcH : desH;
		for (int i = 0; i <= distance; i++) { /* 垂直方向 */
			tabY[db] = sb;
			tems += srcH;
			temd += desH;
			if (tems > distance) {
				tems -= distance;
				sb++;
			}
			if (temd > distance) {
				temd -= distance;
				db++;
			}
		}

		sb = 0;
		db = 0;
		tems = 0;
		temd = 0;
		distance = srcW > desW ? srcW : desW;
		for (int i = 0; i <= distance; i++) { /* 水平方向 */
			tabX[db] = (short) sb;
			tems += srcW;
			temd += desW;
			if (tems > distance) {
				tems -= distance;
				sb++;
			}
			if (temd > distance) {
				temd -= distance;
				db++;
			}
		}

		// 生成放大缩小后图形像素buf
		int[] desBuf = new int[desW * desH];
		int dx = 0;
		int dy = 0;
		int sy = 0;
		int oldy = -1;
		for (int i = 0; i < desH; i++) {
			if (oldy == tabY[i]) {
				System.arraycopy(desBuf, dy - desW, desBuf, dy, desW);
			} else {
				dx = 0;
				for (int j = 0; j < desW; j++) {
					desBuf[dy + dx] = srcBuf[sy + tabX[j]];
					dx++;
				}
				sy += (tabY[i] - oldy) * srcW;
			}
			oldy = tabY[i];
			dy += desW;
		}

		// 生成图片
		desImg = Image.createRGBImage(desBuf, desW, desH, true);
		return desImg;
	}
	

public static Image scaleImage(Image original, int newWidth, int newHeight) {
		int[] rawInput = new int[original.getHeight() * original.getWidth()];
		original.getRGB(rawInput, 0, original.getWidth(), 0, 0, original
				.getWidth(), original.getHeight());

		int[] rawOutput = new int[newWidth * newHeight];

		// YD compensates for the x loop by subtracting the width back out
		int YD = (original.getHeight() / newHeight) * original.getWidth()
				- original.getWidth();
		int YR = original.getHeight() % newHeight;
		int XD = original.getWidth() / newWidth;
		int XR = original.getWidth() % newWidth;
		int outOffset = 0;
		int inOffset = 0;

		for (int y = newHeight, YE = 0; y > 0; y--) {
			for (int x = newWidth, XE = 0; x > 0; x--) {
				rawOutput[outOffset++] = rawInput[inOffset];
				inOffset += XD;
				XE += XR;
				if (XE >= newWidth) {
					XE -= newWidth;
					inOffset++;
				}
			}
			inOffset += YD;
			YE += YR;
			if (YE >= newHeight) {
				YE -= newHeight;
				inOffset += original.getWidth();
			}
		}
		return Image.createRGBImage(rawOutput, newWidth, newHeight, true);
	}

 

我将100*100的图放大到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的效果好一点。再放大点就基本一样了看不出区别了。

 

效率上我用6120c测了下：

resizeImage 54~56(μs),

ZoomImage  58~60(μs),

scaleImage   63~65(μs)

 

仅供参考，其实没多大区别的，呵呵。