高斯模糊的实现

今天设计提出来一个需求，第一耳听到时，我就蒙逼了。

她说：”这个头像的背景你就用用户头像的图标高斯模糊100 + 黑色的蒙层30%的不透明“。

后来经过我的不懈努力，在网上找到了完美的解决方案，惊奇的发现，所谓高大上的高斯模糊又称为”毛玻璃效果“。说毛玻璃效果就很easy了，网上一搜一大把的实现方式，结果都是使用的一个叫做BlurUtil里面的fastblur的方法。

实现起来相当的方便。

/** * 毛玻璃处理类 * @author ycf */public class BlurUtil {@SuppressLint("NewApi")public static Bitmap fastblur(Context context, Bitmap sentBitmap, int radius) {if (VERSION.SDK_INT > 16) //判断SDK的版本，可以更换{Bitmap bitmap = sentBitmap.copy(sentBitmap.getConfig(), true);final RenderScript rs = RenderScript.create(context);final Allocation input = Allocation.createFromBitmap(rs,sentBitmap, Allocation.MipmapControl.MIPMAP_NONE,Allocation.USAGE_SCRIPT);final Allocation output = Allocation.createTyped(rs,input.getType());final ScriptIntrinsicBlur script = ScriptIntrinsicBlur.create(rs,Element.U8_4(rs));script.setRadius(radius);/* e.g. 3.f */script.setInput(input);script.forEach(output);output.copyTo(bitmap);return bitmap;} Bitmap 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];        Log.e("pix", w + " " + h + " " + pix.length);        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++)             {                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);}}