Android 生成模糊图片

项目中常用到背景虚化，可以通过生成模糊图像来实现，下面是从网上找到的一个实现，帖子也是转载的估计，原博客无从查起。有什么问题可以留言。

用的是bitmap.setPixels方法(bitmap.setPixels还可以实现其他效果，具体自行搜索)，体实现如下：

public static Bitmap doBlur(Bitmap sentBitmap, int radius, boolean canReuseInBitmap) {    // Stack Blur v1.0 from    // http://www.quasimondo.com/StackBlurForCanvas/StackBlurDemo.html    //    // Java Author: Mario Klingemann <mario at quasimondo.com>    // http://incubator.quasimondo.com    // created Feburary 29, 2004    // Android port : Yahel Bouaziz <yahel at kayenko.com>    // http://www.kayenko.com    // ported april 5th, 2012    // This is a compromise between Gaussian Blur and Box blur    // It creates much better looking blurs than Box Blur, but is    // 7x faster than my Gaussian Blur implementation.    //    // I called it Stack Blur because this describes best how this    // filter works internally: it creates a kind of moving stack    // of colors whilst scanning through the image. Thereby it    // just has to add one new block of color to the right side    // of the stack and remove the leftmost color. The remaining    // colors on the topmost layer of the stack are either added on    // or reduced by one, depending on if they are on the right or    // on the left side of the stack.    //    // If you are using this algorithm in your code please add    // the following line:    //    // Stack Blur Algorithm by Mario Klingemann <[e-mail]>    Bitmap bitmap;    if (canReuseInBitmap) {        bitmap = sentBitmap;    } else {        bitmap = sentBitmap.copy(sentBitmap.getConfig(), true);    }    if (radius < 1) {        return (null);    }    int w = bitmap.getWidth();    int h = bitmap.getHeight();    int[] pix = new int[w * h];    bitmap.getPixels(pix, 0, w, 0, 0, w, h);    int wm = w - 1;    int hm = h - 1;    int wh = w * h;    int div = radius + radius + 1;    int r[] = new int[wh];    int g[] = new int[wh];    int b[] = new int[wh];    int rsum, gsum, bsum, x, y, i, p, yp, yi, yw;    int vmin[] = new int[Math.max(w, h)];    int divsum = (div + 1) >> 1;    divsum *= divsum;    int dv[] = new int[256 * divsum];    for (i = 0; i < 256 * divsum; i++) {        dv[i] = (i / divsum);    }    yw = yi = 0;    int[][] stack = new int[div][3];    int stackpointer;    int stackstart;    int[] sir;    int rbs;    int r1 = radius + 1;    int routsum, goutsum, boutsum;    int rinsum, ginsum, binsum;    for (y = 0; y < h; y++) {        rinsum = ginsum = binsum = routsum = goutsum = boutsum = rsum = gsum = bsum = 0;        for (i = -radius; i <= radius; i++) {            p = pix[yi + Math.min(wm, Math.max(i, 0))];            sir = stack[i + radius];            sir[0] = (p & 0xff0000) >> 16;            sir[1] = (p & 0x00ff00) >> 8;            sir[2] = (p & 0x0000ff);            rbs = r1 - Math.abs(i);            rsum += sir[0] * rbs;            gsum += sir[1] * rbs;            bsum += sir[2] * rbs;            if (i > 0) {                rinsum += sir[0];                ginsum += sir[1];                binsum += sir[2];            } else {                routsum += sir[0];                goutsum += sir[1];                boutsum += sir[2];            }        }        stackpointer = radius;        for (x = 0; x < w; x++) {            r[yi] = dv[rsum];            g[yi] = dv[gsum];            b[yi] = dv[bsum];            rsum -= routsum;            gsum -= goutsum;            bsum -= boutsum;            stackstart = stackpointer - radius + div;            sir = stack[stackstart % div];            routsum -= sir[0];            goutsum -= sir[1];            boutsum -= sir[2];            if (y == 0) {                vmin[x] = Math.min(x + radius + 1, wm);            }            p = pix[yw + vmin[x]];            sir[0] = (p & 0xff0000) >> 16;            sir[1] = (p & 0x00ff00) >> 8;            sir[2] = (p & 0x0000ff);            rinsum += sir[0];            ginsum += sir[1];            binsum += sir[2];            rsum += rinsum;            gsum += ginsum;            bsum += binsum;            stackpointer = (stackpointer + 1) % div;            sir = stack[(stackpointer) % div];            routsum += sir[0];            goutsum += sir[1];            boutsum += sir[2];            rinsum -= sir[0];            ginsum -= sir[1];            binsum -= sir[2];            yi++;        }        yw += w;    }    for (x = 0; x < w; x++) {        rinsum = ginsum = binsum = routsum = goutsum = boutsum = rsum = gsum = bsum = 0;        yp = -radius * w;        for (i = -radius; i <= radius; i++) {            yi = Math.max(0, yp) + x;            sir = stack[i + radius];            sir[0] = r[yi];            sir[1] = g[yi];            sir[2] = b[yi];            rbs = r1 - Math.abs(i);            rsum += r[yi] * rbs;            gsum += g[yi] * rbs;            bsum += b[yi] * rbs;            if (i > 0) {                rinsum += sir[0];                ginsum += sir[1];                binsum += sir[2];            } else {                routsum += sir[0];                goutsum += sir[1];                boutsum += sir[2];            }            if (i < hm) {                yp += w;            }        }        yi = x;        stackpointer = radius;        for (y = 0; y < h; y++) {            // Preserve alpha channel: ( 0xff000000 & pix[yi] )            pix[yi] = (0xff000000 & pix[yi]) | (dv[rsum] << 16) | (dv[gsum] << 8) | dv[bsum];            rsum -= routsum;            gsum -= goutsum;            bsum -= boutsum;            stackstart = stackpointer - radius + div;            sir = stack[stackstart % div];            routsum -= sir[0];            goutsum -= sir[1];            boutsum -= sir[2];            if (x == 0) {                vmin[y] = Math.min(y + r1, hm) * w;            }            p = x + vmin[y];            sir[0] = r[p];            sir[1] = g[p];            sir[2] = b[p];            rinsum += sir[0];            ginsum += sir[1];            binsum += sir[2];            rsum += rinsum;            gsum += ginsum;            bsum += binsum;            stackpointer = (stackpointer + 1) % div;            sir = stack[stackpointer];            routsum += sir[0];            goutsum += sir[1];            boutsum += sir[2];            rinsum -= sir[0];            ginsum -= sir[1];            binsum -= sir[2];            yi += w;        }    }    bitmap.setPixels(pix, 0, w, 0, 0, w, h);    return (bitmap);}