RQRCodeCore

rqrcode_core is a Ruby library for encoding QR Codes.  The simple interface
(with no runtime dependencies) allows you to create QR Code data structures.
It was originally adapted in 2008 from a Javascript library by Kazuhiko
Arase: https://github.com/kazuhikoarase.

Features

* rqrcode_core is a ruby only library. It requires no native libraries. Just
  Ruby!
* It is an encoding library. You can't decode QR codes with it.
* The interface is simple and assumes you just want to encode a string into
  a QR code.
* QR code is trademarked by Denso Wave inc.

rqrcode_core is the basis of the popular rqrcode gem:
https://github.com/whomwah/rqrcode.  This gem allows you to generate
different renderings of your QR code, including png, svg and ansi.