Upgrade Lexend with SPAC+XTRA

[RosaWagner]

upstream: https://github.com/googlefonts/lexend
Current work in progress in: https://github.com/googlefonts/lexend/tree/wdth-spac-axes

[RosaWagner]

This is on hold until SPAC axis is registered.

I don't think we need to register the LXND axis in the axis registry. I would be in favour of:

• updating the Lexend static families with last fixes + arabic set
• integrating LXND only in the STAT table as multi-axes (format 4) with fallbacks deca, giga, mega etc. (when it becomes possible)

Indeed, having the deca,mega,etc instances in the ZIP file would create a conflict with the existing families (which has the medium weight as default regular) if users install statics from Lexend and Lexend Deca for example. Also, I don't think we can register axis which has multiple axes locations…

EDIT: I had confirmation for all of this :)

[RosaWagner]

It was finally decided to release the VF with ONE custom axis (hyper expansion) instead of 2 (space and width). It will be released without the arabic set. Indeed the arabic has been designed in a different weight range, it will be therefore released in a separate family.

[RosaWagner]

Hyper Expansion (HEXP)
Expansion of inner and outer space of letterforms.
min:-24, default:0, max:24

• Fallbacks could follow the unit prefix (as it is in the Lexend families) and value could be power factor (eg. deca is 10^1 > 1, Mega is 10^6 > 6)
• Lexend would have min/default: 1, max=21
• Note: the actual Lexend families doesn't seem to follow this progression. It goes in alphabetic order, instead of power order (I don't know why)

[davelab6]

Alphabetical order was so the font menu lists them in order

[davelab6]

I propose the axis be a % so it's self referential

[davelab6]

So it's ranges 0 to 100, default 0