Support DesignSpace version 5 with discrete axes, uservalue dimensions, etc.

[anthrotype]

Changelog https://fonttools.readthedocs.io/en/latest/designspaceLib/index.html#version-5-0

Also, search for "Added in version 5.0" in https://fonttools.readthedocs.io/en/latest/designspaceLib/xml.html

related issues:
#836
#813

[rsheeter]

Last time this came up I could not locate any open source project using DSv5. Do we know of one? Or of projects that want to use it?

[anthrotype]

we got at least two issues filed against this in the last month only by two different people so I suspect there is some interest.

Last time this came up I could not locate any open source project using DSv5.

Maybe @jenskutilek or @justvanrossum can point us to some?

[justvanrossum]

Sorry, I only know of private projects within BlackFoundry that use DS5.

[jenskutilek]

I have updated most of our VFs at LucasFonts to DS5 because of the ability to avoid redundancy by having the upright and italic VFs in one DS file, and because it makes building STAT tables with a separate tool obsolete. We even already build some fonts with avar2.

I'm not aware of any DS5 open source projects either, but if you are interested, I could prepare some minimal example.

[anthrotype]

if you are interested, I could prepare some minimal example.

test fonts would be great, thank you!

[jenskutilek]

Finally, here's a demo project using a v5 designspace. It only contains two characters: "e→"

The e is incompatible between roman and italic, and the arrow should change its number of dots along the optical size axis.

fontc-ds5.zip

It builds with fontmake, but currently not with fontc.

[jenskutilek]

Here's another version, I've thrown in some avar2 for good measure. Now with correct DS5.1 ;)

fontc-ds5-avar2.zip