ZXing with Front Camera within a Defined Boundary

Hello everyone,

I am developing an app exclusively for a tablet and I am facing a problem that has two parts to it:

1. I need to scan a QR code using the front camera.
2. When the camera activates, the camera stream should be visible only in a defined space rather than taking the whole screen.

I have downloaded the sample by @Redth from GitHub and it is working for back camera. How can I change it to work for the front one? Furthermore, also guide me on how to show the camera stream within a defined boundary rather than the whole screen.

Thanks.