Android Blur View (Blur background behind the view)

I am trying to make the bottom part of an Image blur for the view on top it like in the image.

I tried blurring it using Rendenscript but I am not able to blur only the part behind the view. :(

I have seen many libraries but almost all of them blur the entire image, but not a part of it.

Also, an important part is that I am using this inside a ViewPager and hence needs to be fast and dynamic something like this in IOS which redraws itself the moment image behind it changes.

Any help is appreciated. Thanks for stopping by!

My xml:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://ift.tt/nIICcg"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:gravity="center"
    android:orientation="vertical" >

    <ImageView
        android:id="@+id/image"
        android:src="@drawable/broadstairs"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:scaleType="centerCrop"
        android:layout_centerInParent="true"/>

    <TextView
        android:id="@+id/text"
        android:layout_width="match_parent"
        android:layout_height="200dp"
        android:text="Hello World"
        android:gravity="center"
        android:layout_alignParentBottom="true"
        android:textColor="@android:color/white"
        android:textStyle="bold"
        android:textSize="36sp"/>
</RelativeLayout>

My code:

BlurBuilder.java

public class BlurBuilder {
    private static final float BITMAP_SCALE = 0.1f;
    private static final float BLUR_RADIUS = 7.5f;

    public static Bitmap blur(Context context, Bitmap image) {
        int width = Math.round(image.getWidth() * BITMAP_SCALE);
        int height = Math.round(image.getHeight() * BITMAP_SCALE);

        Bitmap inputBitmap = Bitmap.createScaledBitmap(image, width, height, false);
        Bitmap outputBitmap = Bitmap.createBitmap(inputBitmap);

        RenderScript rs = RenderScript.create(context);
        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;
    }

    @SuppressLint("NewApi")
    public static void blur(final Context context, final Bitmap bitmap, final View view) {

        new AsyncTask<Void, Void, Bitmap>() {

            @Override
            protected Bitmap doInBackground(Void... params) {
                Paint paint = new Paint();
                paint.setFilterBitmap(true);
                Bitmap cropImage = Bitmap.createBitmap(bitmap, 0, bitmap.getHeight() - view.getHeight(), bitmap.getWidth(), view.getHeight());

                return BlurBuilder.blur(context, cropImage);
            }


            @Override
            protected void onPostExecute(Bitmap bitmap) {
                super.onPostExecute(bitmap);
                if (bitmap != null) {
                    int sdk = android.os.Build.VERSION.SDK_INT;
                    if (sdk < android.os.Build.VERSION_CODES.JELLY_BEAN) {
                        view.setBackgroundDrawable(new BitmapDrawable(context.getResources(), bitmap));
                    } else {
                        view.setBackground(new BitmapDrawable(context.getResources(), bitmap));
                    }

                }

            }
        }.execute();


    }

}

In my MainActivity's onCreate I do:

BlurBuilder.blur(BitmapActivity.this, ((BitmapDrawable) mView.getDrawable()).getBitmap(), mDummyView);

Below is the result: