"Zean00"'s Fuse Qreader: how to change camera viewport?

I tried Zean00’s Fuse Qreader (Android version) which I found excellent. It worked “out-of-the-box” with great satisfaction.

Now I would like to change a little the viewport’s camera for example to a square 200x200px and apply (inside the square viewport) a animation of a horizontal green bar that seems to laserscan the QR code as we may see in many QRreader apps.

With <CameraView> I can easily change the viewport but I don’t know how I can do it with Qreader library, nor I know if it can be done.

Any code snippet?
Thank you