Here's some code you can dig into: https://github.com/zxing/zxing https://github.com/zxing/zxing It's a very good one, and one that has been copied for a lot o

Here's some code you can dig into: https://github.com/zxing/zxing https://github.com/zxing/zxing It's a very good one, and one that has been copied for a lot of custom QR scanners