No documentation available
See this APEX demo
I use that demo application also to develop and test this package. So it might be possible that the demo shows more than can be done with the lastest version available at github, for instance PDF417. And that application itself is NOT available.
Supports QR-code, Aztec, data matrix, EAN-8, EAN-13, UPC-A, code39, code128, Interleaved 2 of 5 (ITF) and some (RM4SCC, Australia Post 4-State Customer Code, KIX) postal 4-State barcodes
Output format includes png, svg, git, bmp and jpg.