android dialog背景模糊化效果实现方法

private Bitmap takeScreenShot(Activity activity) {  View view = activity.getWindow().getDecorView();  view.setDrawingCacheEnabled(true);  view.buildDrawingCache();  Bitmap b1 = view.getDrawingCache();  // 获取屏幕长和高  int width = activity.getResources().getDisplayMetrics().widthPixels;  int height = activity.getResources().getDisplayMetrics().heightPixels;  Bitmap bmp = Bitmap.createBitmap(b1, 0, 0, width, height);  view.destroyDrawingCache();  return bmp; }

//blurBackgroundDrawer为模糊后的背景图片 Window window = getWindow(); window.setBackgroundDrawable(new BitmapDrawable(mContext.getResources(), blurBackgroundDrawer));

public class FastBlurUtility { /**  * 获得模糊化的背景图片  * @param activity 获取模糊化的背景activity  * @return 模糊化的背景图片  */ public static Bitmap getBlurBackgroundDrawer(Activity activity) {  Bitmap bmp = takeScreenShot(activity);  return startBlurBackground(bmp); } /**  * 截屏  * @param activity 截屏的activity  * @return 截屏图片  */ private static Bitmap takeScreenShot(Activity activity) {  View view = activity.getWindow().getDecorView();  view.setDrawingCacheEnabled(true);  view.buildDrawingCache();  Bitmap b1 = view.getDrawingCache();  // 获取屏幕长和高  int width = activity.getResources().getDisplayMetrics().widthPixels;  int height = activity.getResources().getDisplayMetrics().heightPixels;  Bitmap bmp = Bitmap.createBitmap(b1, 0, 0, width, height);  view.destroyDrawingCache();  return bmp; } private static Bitmap startBlurBackground(Bitmap bkg) {  long startMs = System.currentTimeMillis();  float radius = 20; //模糊程度  Bitmap overlay = fastblur(small(bkg), (int) radius);  Log.i("FastBlurUtility", "=====blur time:" + (System.currentTimeMillis() - startMs));  return big(overlay); } /**  * 放大图片  * @param bitmap 需要放大的图片  * @return 放大的图片  */ private static Bitmap big(Bitmap bitmap) {  Matrix matrix = new Matrix();  matrix.postScale(4f, 4f);  Bitmap resizeBmp = Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth(), bitmap.getHeight(), matrix, true);  return resizeBmp; } /**  * 缩小图片  * @param bitmap 需要缩小的图片  * @return 缩小的图片  */ private static Bitmap small(Bitmap bitmap) {  Matrix matrix = new Matrix();  matrix.postScale(0.25f, 0.25f);  Bitmap resizeBmp = Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth(), bitmap.getHeight(), matrix, true);  return resizeBmp; } /**  * 将图片模糊化  * @param sentBitmap 需要模糊的图片  * @param radius  模糊程度  * @return 模糊后的图片  */ private static Bitmap fastblur(Bitmap sentBitmap, int radius) {  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];  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); }}