We have a tradition here at Clearleft of having the occasional lunchtime braindump. They’re somewhat sporadic, but it’s always a good day when there’s a “brown bag” gathering.

Jeremy Keith
Jeremy Keith
21st February 2017

When Google's AMP format came out and I had done some investigating, I led a brown bag playback on that. Recently Mark did one on Fractal so that everyone knew how work on that was progressing.

Today Richard gave us a quick brown bag talk on variable web fonts. He talked us through how these will work on the web and in operating systems. We got a good explanation of how these fonts would get designed—the type designer designs the "extreme" edges of size, weight, or whatever, and then the file format itself can extrapolate all the in-between stages. So, in theory, one single font file can hold hundreds, thousands, or hundreds of thousands of potential variations. It feels like switching from bitmap images to SVG—there's suddenly much greater flexibility.

A variable font is a single font file that behaves like multiple fonts.

There were a couple of interesting tidbits that Rich pointed out...

While this is a new file format, there isn't going to be a new file extension. These will be .ttf files, and so by extension, they can be .woff and .woff2 files too.

This isn't some proposed theoretical standard: an unprecedented amount of co-operation has gone into the creation of this format. Adobe, Apple, Google, and Microsoft have all contributed. Agreement is the hardest part of any standards process. Once that's taken care of, the technical solution follows quickly. So you can expect this to land very quickly and widely.

This technology is landing in web browsers before it lands in operating systems. It's already available in the Safari Technology Preview. That means that for a while, the very best on-screen typography will be delivered not in eBook readers, but in web browsers. So if you want to deliver the absolute best reading experience, look to the web.

And here's the part that I found fascinating...

We can currently use numbers for the font-weight property in CSS. Those number values increment in hundreds: 100, 200, 300, etc. Now with variable fonts, we can start using integers: 321, 417, 183, etc. How fortuitous that we have 99 free slots between our current set of values!

Well, that's no accident. The reason why the numbers were originally specced in increments of 100 back in 1996 was precisely so that some future sci-fi technology could make use of the ranges in between. That's some future-friendly thinking! And as Håkon wrote:

One of the reasons we chose to use three-digit numbers was to support intermediate values in the future. And the future is now :)

Needless to say, variable fonts will be covered in Richard's forthcoming book.

This was originally posted on my own site.