Zoom in and out camera Scanner

Hi everyone,
I have been working with Bar/QR code scanner app in flutter. I have followed this guy
[ by Pawan Kumar]
(https://github.com/iampawan/FlutterQRScanner-App/blob/master/lib/main.dart)

I am able to scan the code using the code and It works perfectly fine and now I would like to know is there any way I can Implement Zoom in and out for the camera scanner.
I used Zoom widget which works only on existing image or a page. I want to have a controller in the scanner page where I can adjust the scanning.
I am attaching the gif file. I would like to achive the same zoom in and out in flutter

qr1

thanks in advance