xamarin.android 图片高斯模糊效果

代码如下：

 　　　　private static float BITMAP_SCALE = 0.1f;
        private static float BLUR_RADIUS = 12.0f;

        public static Bitmap Blur(Context ctx, Bitmap image)
        {
            int width =(int) Math.Round(image.Width * BITMAP_SCALE);
            int height =(int) Math.Round(image.Height * BITMAP_SCALE);

            Bitmap inputBitmap = Bitmap.CreateScaledBitmap(image, width, height, false);
            Bitmap outputBitmap = Bitmap.CreateBitmap(inputBitmap);

            RenderScript rs = RenderScript.Create(ctx);
            ScriptIntrinsicBlur theIntrinsic = ScriptIntrinsicBlur.Create(rs, Element.U8_4(rs));
            Allocation tmpIn = Allocation.CreateFromBitmap(rs, inputBitmap);
            Allocation tmpOut = Allocation.CreateFromBitmap(rs, outputBitmap);
            theIntrinsic.SetRadius(BLUR_RADIUS);
            theIntrinsic.SetInput(tmpIn);
            theIntrinsic.ForEach(tmpOut);
            tmpOut.CopyTo(outputBitmap);

            return outputBitmap;
        }

 var bitmap = ((BitmapDrawable)Resources.GetDrawable(Resource.Drawable.hero)).Bitmap;

var blur = Blur(this, bitmap);
var viewImage = FindViewById<ImageView>(Resource.Id.imageView1);
    viewImage.SetImageBitmap(blur); 

效果如下：