FontBureau profile for checks on proposed new variation axes

[felipesanches]

I have just had a nice videocall with Mirko (@bghryct) in which he told me he's interested in implementing FontBakery checks for the new variation axes proposed here:
https://variationsguide.typenetwork.com/

I believe that we can use the same strategy that we're using for the gf-axis-registry checks by employing textproto files for those axes. But I would place these new axes on a separate profile (Mirko suggested to call it the fontbureau profile). If these axes are added to the GFAxisRegistry in the future, it would then be super easy to migrate the textproto files into the googlefonts profile.

[felipesanches]

@bghryct, please post here the contents of a textproto file for at least one of the newly proposed axes. The structure of such textproto files can be seen here: https://github.com/google/fonts/tree/fa38f09d14b5c976a5b0c140cdfbc562023fc38e/axisregistry

[bghryct]

# ytlc based on https://variationsguide.typenetwork.com/
tag: "ytlc"
display_name: "y transparent lowercase"
min_value: 0
max_value: 1000
default_value: 500
precision: 0
fallback {
  name: "Non ytlc"
  value: 0
}
fallback {
  name: "ytlc"
  value: 1
}
description:
  " assigns a “white” per mille value to each instance of the design space"
  " it is possible to think of this white space as the increase in counter"
  " forms accompanying the increase in the x-height of letter forms"
  " Imagine an h where the x-height increases but the ascender remains the same"
  " In static fonts, this change would occur in instances with per-mille values"
  " appended to their names. e.g. myfont-480.ttf"

[bghryct]

I'm not sure if this is absolutely correct @felipesanches as I don't fully understand the fallback value meanings, or what precision means for that matter.

Really appreciate you taking the time to walk me through fontbakery check writing this morning.

Also I realize that the first line of the textproto file should reference a font project with the axis in use. I have a project using ytlc but it's not ready for the light of day, or the darkmode of github, yet.

[vv-monsalve]

Check out these discussions about new custom axis registries; maybe they are of any help on the process, and you could participate also :)

google/fonts#2846
google/fonts#2853
google/fonts#2888

[felipesanches]

@bghryct, can you provide the textproto files for all other proposed axes?

[bghryct]

@felipe @vv-monsalve
I will when I get a chance, I'm a bit busy with client work atm. Should be able to within the next week and a half.

Where should I include the textproto files?

[felipesanches]

you can send a PR adding them to this directory: Lib/fontbakery/data/. There are already some other textprotos in there.

[bghryct]

@felipesanches
Sounds good