android 获取当前屏幕作为毛玻璃模糊背景Acitivity作为弹出框。

使用：

1.在执行弹出界面前，先将其当前屏幕截图。

 BlurBuilder.snapShotWithoutStatusBar(getActivity());

2.为了确保界面切入无效果。

 startActivity(wechatIntent);
         context.overridePendingTransition(
                 android.view.animation.Animation.INFINITE,
                 android.view.animation.Animation.INFINITE);

3.在切换的页面中初始化背景ImageView：

 private void applyBlur() {
         iv_shared_layout.setImageBitmap(BlurBuilder.blur(iv_shared_layout));
         if (BlurBuilder.isBlurFlag()) {
             iv_shared_layout.setVisibility(View.VISIBLE);
         }
     }

4.在acitivity的super.finish();或者在onDestroy中回收资源：

 @Override
     public void finish() {
         defaultFinishNotActivityHelper();
         BlurBuilder.recycle();
         overridePendingTransition(android.view.animation.Animation.INFINITE,
                 android.view.animation.Animation.INFINITE);
     }

毛玻璃模糊效果使用类：

 public class BlurBuilder {

     private static final float BITMAP_SCALE = 0.4f;
     private static final float BLUR_RADIUS = 7.5f;

     private static Bitmap tab_bg = null;
     private static Bitmap overlay = null;
     private static boolean blurFlag = false;

     public static boolean isBlurFlag() {
         return BlurBuilder.blurFlag;
     }

     public static void setBlurFlag(boolean blurFlag) {
         BlurBuilder.blurFlag = blurFlag;
     }

     public static Bitmap blur(View v) {
         if (tab_bg == null) {
             android.util.Log.i("", "tab_bg == null");
             blurFlag = false;
             return null;
         }
         blurFlag = true;
         blur(v.getContext(), tab_bg);
         return overlay;
     }

     public static void blur(Context ctx, Bitmap image) {
         if (overlay != null) {
             recycle();
         }
         try {
             int width = Math.round(image.getWidth() * BITMAP_SCALE);
             int height = Math.round(image.getHeight() * BITMAP_SCALE);

             overlay = Bitmap.createScaledBitmap(image, (int) (width),
                     (int) (height), false);

             overlay = FastBlur.doBlur(overlay, (int) BLUR_RADIUS, true);
         } catch (Exception e) {
             e.printStackTrace();
         }
     }

     public static void getScreenshot(View v) {
         if (tab_bg != null) {
             recycle();
         }
         try {
             tab_bg = Bitmap.createBitmap(v.getWidth(), v.getHeight(),
                     Bitmap.Config.RGB_565);
             Canvas c = new Canvas(tab_bg);
             v.draw(c);
         } catch (Exception e) {
             e.printStackTrace();
         }
     }

     /**
      * 获取当前屏幕截图，不包含状态栏
      *
      * @param activity
      * @return
      */
     public static void snapShotWithoutStatusBar(Activity activity) {
         if (tab_bg != null) {
             recycle();
         }
         View view = activity.getWindow().getDecorView();
         try {
             view.setDrawingCacheEnabled(true);
             view.buildDrawingCache();
             tab_bg = view.getDrawingCache();
             Rect frame = new Rect();
             activity.getWindow().getDecorView()
                     .getWindowVisibleDisplayFrame(frame);
             int statusBarHeight = frame.top;

             int width = ScreenUtils.getScreenWidth(activity);
             int height = ScreenUtils.getScreenHeight(activity);
             tab_bg = Bitmap.createBitmap(tab_bg, 0, statusBarHeight, width,
                     height - statusBarHeight);
             view.destroyDrawingCache();
         } catch (Exception e) {
             e.printStackTrace();
             getScreenshot(view);
         }
     }

     public static void recycle() {

         try {
             if (tab_bg != null) {
                 tab_bg.recycle();
                 System.gc();
                 tab_bg = null;
             }
             if (overlay != null) {
                 overlay.recycle();
                 System.gc();
                 overlay = null;
             }
         } catch (Exception e) {
             e.printStackTrace();
         }
     }
 }

毛玻璃模糊效果类：

 public class FastBlur {

     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);
     }
 }