Add human readable names for cvXX and ssXX font features

[kovidgoyal]

In my application (kitty) I am creating UI that allows users to specify what font features they want to enable, for a given face. The stylistic set and character variation font features can have optional human readable names associated with them that make much more sense than cv01 ss01 etc. See the OpenType spec FeatureParam tables for details:
https://learn.microsoft.com/en-ca/typography/opentype/spec/features_ae#tag-cv01--cv99

For ssXX features just a single name is needed. For cvXX features a name for each parameter value is also needed.

You can see Adobe Source Code Pro as an example of a font that actually names at least ssXX features.

[tonsky]

Hi! Happy to add! I am using Kitty right now, and the perspective of having settings UI makes me very excited!

[kovidgoyal]

Cool, here are some screenshots showing fira code (VF) in the new config UI. I plan to eventually add UI to select features to the first screen in this UI.

[tonsky]

Even the variable axis! That’s amazing. I don’t think I know a single code editor or terminal that has UI for that, but I have been dreaming about one for a while now https://x.com/nikitonsky/status/1793641900303360137

[romashamin]

Hey @kovidgoyal what you are doing is amazing! Can I use your screenshots on my Twitter to tell people what you are working on?

[kovidgoyal]

Sure, but it will be a month or so before its ready for testing.

[kovidgoyal]

Here is a screenshot of how it looks now with support for features.