Works in portrait and landscape orientation can read inverted codes is Material Design and can also generate barcodes.

Uses the ZXing ("Zebra Crossing") barcode scanning library. Supported barcode formats are: AZTEC CODABAR CODE 39 CODE 93 CODE 128 DATA MATRIX EAN 8 EAN 13 ITF MAXICODE PDF417 QR CODE RSS 14 RSS EXPANDED UPC A UPC E and UPC EAN EXTENSION.

This is open source:
https://github.com/markusfisch/BinaryEye