Android Studio: How to convert perview to bitmap?

Question

I want to convert to camera preview into Bitmap format and put it back to Frame layout, anyone could help me? Thank you~

preview = new Preview(applicationInterface, (this.findViewById(R.id.preview)));

<FrameLayout
    android:id="@+id/preview"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerInParent="true"
    />