Android 实现图片高斯模糊算法，真正有效的工具类

import android.graphics.Bitmap;
import android.graphics.Color;

public class FastBlur {
    /***
     * 高斯模糊算法
     * @param bmp 要处理的图像
     * @param radius 处理的半径
     * @return
     */
    public static Bitmap BoxBlurFilter(Bitmap bmp,float radius ) {
     int width= bmp.getWidth();
     int height = bmp.getHeight();
     int[] inPixels = new int[width * height];
     int[] outPixels = new int[width * height];
     Bitmap bitmap = Bitmap.createBitmap(width, height,Bitmap.Config.ARGB_8888);
     bmp.getPixels(inPixels,0,width,0,0, width, height);
     for (int i= 0; i < 5; i++) {
      blur(inPixels, outPixels, width, height,radius);
      blur(outPixels,inPixels, height, width,radius);
        
     }
     blurFractional(inPixels, outPixels, width, height, radius);
     blurFractional(outPixels,inPixels, height, width,radius);
     bitmap.setPixels(inPixels,0, width, 0,0, width, height);
    // Drawable drawable = new BitmapDrawable(bitmap);
    return bitmap;
  }
    
 public static void blur(int[]in, int[] out, int width,int height, float radius)
    {
        int widthMinus1 = width - 1;
        int r = (int) radius;
        int tableSize = 2 * r + 1;
        int divide[] = new int[256 * tableSize];
        for (int i = 0; i < 256 * tableSize; i++)
         divide[i] = i / tableSize;
         int inIndex = 0;
         for (int y = 0; y < height; y++) {
         int outIndex = y;
         int ta = 0,
             tr = 0,
             tg = 0,
             tb = 0;
             
     for (int i = -r; i <= r; i++) {
         int rgb = in[inIndex + clamp(i, 0, width - 1)];
             ta+= (rgb >> 24) & 0xff;
             tr += (rgb >> 16) & 0xff;
             tg += (rgb >> 8) & 0xff;
             tb += rgb & 0xff;
         }
             
        for (int x = 0; x < width; x++) {
         out[outIndex] = (divide[ta] << 24) | (divide[tr] << 16)  |(divide[tg] << 8) | divide[tb];
         int i1= x + r + 1;
         if (i1 > widthMinus1)
            i1 = widthMinus1;
         int i2 = x - r;
         if (i2 < 0)
         i2 = 0;
         int rgb1= in[inIndex + i1];
         int rgb2= in[inIndex + i2];
         ta += ((rgb1 >> 24) & 0xff) - ((rgb2 >> 24) & 0xff);
         tr+= ((rgb1 & 0xff0000) - (rgb2 & 0xff0000)) >> 16;
         tg += ((rgb1 & 0xff00) - (rgb2 & 0xff00)) >> 8;
         tb += (rgb1 & 0xff)- (rgb2 & 0xff);
         outIndex += height;
        }
        inIndex += width;
         }
 }
             
    
public static void blurFractional(int[] in, int[] out, int width, int height,float radius)
 {
    radius -= (int) radius;
    float f = 1.0f / (1 +2*radius);
    int inIndex= 0;
    for (int y= 0; y < height; y++) {
    int outIndex = y;
    out[outIndex] = in[0];
    outIndex += height;
   for (int x = 1; x < width - 1; x++) {
   int i = inIndex + x;
   int rgb1 = in[i - 1];
   int rgb2 = in[i];
   int rgb3 = in[i + 1];
   int a1 = (rgb1 >> 24) & 0xff;
   int r1 = (rgb1 >> 16)& 0xff;
   int g1 = (rgb1 >> 8)& 0xff;
   int b1 = rgb1 & 0xff;
   int a2 = (rgb2 >> 24) & 0xff;             
   int r2 = (rgb2 >> 16) & 0xff;
   int g2 = (rgb2 >> 8) & 0xff;
   int b2 = rgb2 & 0xff;
   int a3 = (rgb3 >> 24) & 0xff;
   int r3 = (rgb3 >> 16)& 0xff;
   int g3 = (rgb3 >> 8) & 0xff;
   int b3 = rgb3 & 0xff;
     a1= a2 + (int)((a1 + a3) * radius);
     r1 = r2 + (int)((r1 + r3) * radius);
     g1 = g2 + (int)((g1 + g3) * radius);
     b1 = b2 + (int)((b1 + b3) * radius);
     a1 *= f;
     r1 *= f;
     g1 *= f;
     b1 *= f;
     out[outIndex] = (a1 << 24) | (r1 << 16) | (g1 << 8) | b1;
     outIndex+= height;
     }
    out[outIndex] = in[width - 1];
    inIndex += width;
     }
}
             
 public static int clamp(int x,int a,int b)
 {
     return (x < a) ? a : (x > b) ? b : x;
 }

 public static Bitmap doBlur(Bitmap sentBitmap, int radius, boolean canReuseInBitmap) {

        
        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);
    }
}