[tx] Improvements to UFO handling

[miguelsousa]

• Replace house-made XML parser (e.g. with libxml2)
• Support converting between UFO versions
  • anchors
  • glyph colors
• Change the current -ufo option to write v3 UFOs, or add a new -ufo3 option?
• ... (to be continued)

[benkiel]

Perhaps use ufoLib?

[miguelsousa]

I have no idea. tx is C code.

[benkiel]

Ah, never mind...

[anthrotype]

Cython can be used to go the other way around as well and export a C API from a cython module, so that other C programs can call functions defined in python (via cython).
http://cython.readthedocs.io/en/latest/src/userguide/external_C_code.html#c-api-declarations

It’s doable.

[frankrolf]

Let’s keep in mind that tx is quite fast at converting files, our CJK fonts rely on it quite heavily (correct me if I’m wrong, @kenlunde). It would be a shame to give up the speed benefit.

[kenlunde]

Not only for converting large fonts, but also for subroutinizing them.

[khaledhosny]

I think it is rather useful to have another UFO implementation, especially in a language like C which allows it to be used in more places than a pure Python implementation. It might be even a good idea to turn in into an independent library for better re-use, if it isn’t already the case.

[madig]

(https://github.com/linebender/norad is a WIP effort to make a UFO library in Rust for the WIP font editor Runebender)