[XeTeX] Support of variable OpenType fonts

[Werner LEMBERG]

>> May I /very/ respectfully suggest that while support for colour
>> emoji fonts may well be of interest to some, it would be more in
>> the spirit of TeX to invest that effort into attempting to support
>> the technology that underlies Zapfino Ink
>> <https://tug.org/TUGboat/tb28-2/tb89hagen.pdf>.
> 
> Essentially, it's the same technology for both: Either OpenType 'COLR'
> v1 tables
> 
>   https://docs.microsoft.com/en-us/typography/opentype/spec/colr
> 
> or 'SVG' tables.
> 
>   https://docs.microsoft.com/en-us/typography/opentype/spec/svg

To clarify: This is the technology to use *today*, which is available
and supported by all major platforms, especially in browsers.  I can
imagine that Apple cooked up something proprietary then especially for
Zapfino Ink as a demonstration, and which is of historical interest
only.


    Werner