[Variable Fonts] font naming/metadata proposal

[m4rc1e]

We've been working on two beta VF fonts MarkaziText #1565 and Vollkorn #1571. I thinks it's important we get the metadata for variable fonts established before we sign off on these.

Myself and @davelab6 have been discussing naming in #1571. The STAT table also adds another layer of complexity.

Atm I'm using fontmake's default naming. For Markazi Text #1565 we get the following nametable:

platformID    encodingID    languageID    nameID  nameString
1             0             0       256  Weight
1             0             0       257  Regular
1             0             0       258  Medium
1             0             0       259  SemiBold
1             0             0       260  Bold
3             1          1033         0  Copyright 2017 The Markazi Text Authors (https://github.com/BornaIz/markazitext)
3             1          1033         1  Markazi Text
3             1          1033         2  Regular
3             1          1033         3  1.000;NONE;MarkaziText-Regular
3             1          1033         4  Markazi Text Regular
3             1          1033         5  Version 1.000
3             1          1033         6  MarkaziText-Regular
3             1          1033         8  Borna Izadpanah and Florian Runge
3             1          1033         9  Borna Izadpanah (Arabic designer), Fiona Ross (Arabic design director) and Florian Runge (Latin designer)
3             1          1033        11  http://www.borna.design, http://www.florianrunge.com
3             1          1033        12  http://www.borna.design, http://www.florianrunge.com
3             1          1033        13  This Font Software is licensed under the SIL Open Font License, Version 1.1. This license is available with a FAQ at: http://scripts.sil.org/OFL
3             1          1033        14  http://scripts.sil.org/OFL
3             1          1033       256  Weight
3             1          1033       257  Regular
3             1          1033       258  Medium
3             1          1033       259  SemiBold
3             1          1033       260  Bold

I've manually created the following STAT table

<STAT>
  <Version value="0x00010001"/>
  <DesignAxisRecordSize value="8"/>
  <!-- DesignAxisCount=1 -->
  <DesignAxisRecord>
    <Axis index="0">
      <AxisTag value="wght"/>
      <AxisNameID value="256"/>  <!-- Weight -->
      <AxisOrdering value="0"/>
    </Axis>
  </DesignAxisRecord>
  <!-- AxisValueCount=4 -->
  <AxisValueArray>
    <AxisValue index="0" Format="1">
      <AxisIndex value="0"/>
      <Flags value="0"/>
      <ValueNameID value="257"/>  <!-- Regular -->
      <Value value="160.0"/>
    </AxisValue>
    <AxisValue index="1" Format="1">
      <AxisIndex value="0"/>
      <Flags value="0"/>
      <ValueNameID value="258"/>  <!-- Medium -->
      <Value value="182.0"/>
    </AxisValue>
    <AxisValue index="2" Format="1">
      <AxisIndex value="0"/>
      <Flags value="0"/>
      <ValueNameID value="259"/>  <!-- SemiBold -->
      <Value value="210.0"/>
    </AxisValue>
    <AxisValue index="3" Format="1">
      <AxisIndex value="0"/>
      <Flags value="0"/>
      <ValueNameID value="260"/>  <!-- Bold -->
      <Value value="232.0"/>
    </AxisValue>
  </AxisValueArray>
  <ElidedFallbackNameID value="257"/>  <!-- Regular -->
</STAT>

This gives us the following font menus in Desktop applications

Finally, for filenames we will distinguish between Roman and Italic VF fonts. When Markazi moves out of Beta its filename will be:

MarkaziText-Roman-VF.ttf

Note: 'Roman' and 'VF' will not be added to the names inside the fonts.

When a family includes Italics as a separate VF font, the filenames will be the following:

Vollkorn-Roman-VF.ttf Vollkorn-Italic-VF.ttf

We want to end up with the following font menu.

When we're happy with this proposal, our next step is to write a Font Bakery test.

[laerm0]

Maybe add a new proposals/documentation/etc milestone, @davelab6 ?

[laerm0]

@m4rc1e We're practically good on this now, aye?