The project Ada Bar Codes provides a framework for generating various types of bar codes (1D, or 2D, like QR codes) on different output formats and devices.
Alire crate: https://alire.ada.dev/crates/bar_codes
Mirror: https://github.com/zertovitch/ada-bar-codes
...Complex user interface elements can be realized often in few lines of code. Agar is also extensible at the low-level. The low-level API is documented such that modular drivers can be written which enable Agar applications to work seamlessly under many platforms graphics systems without any change at the application level.