So, lots of pressure here on Affinity to do this. I just want to comment a bit on something. And please note, this is from the perspective that I personally love variable fonts, have made a bunch of them, and can’t imagine personally paying to license any general design tool today that does not support them decently.
Variable font support is NOT trivial
It isn’t just a matter of enabling something. And no, switching out their back-end font engine for Harfbuzz would not be trivial, and even if it were, that would not solve the problem! Don’t get me wrong, either supporting Harfbuzz or supporting variable fonts in their own engine is a huge amount of work. So many assumptions need to be thrown away, in either case. APIs reworked... agh.
But the other huge deal is: user interface aspects of variable fonts are a huge hassle. The names and contents of axes are completely arbitrary and not known in advance by app developers. What is the most axes a font can have? 64K. Maybe the app has some arbitrary limit lower than that. How fine should the stops be on an axis? How many predefined instances should they support per axis? How do they expose predefined instances for variable fonts and how do they make those interact with user-defined instances? Do they just use sliders for everything? Do they support decimals in axis positions or only whole numbers? Manual input of position coordinates, or only the sliders? And on and on.
Without going into the same detail, impacts on layout are similarly huge.
Writing this as former fonts product manager at Adobe (until December 2008), later product management for font management and web fonts at Extensis, and CEO of FontLab
Anyway, I am eager to see this support in Serif’s Affinity products, but please understand it is a heck of a lot of work!
(Is that enough italics and boldface for one post, or should I throw in some more gratuitously here?)