1302685 - [meta] Support OpenType Font Variations (Variable fonts)

Status: NEW

(Core :: Layout: Text and Fonts, enhancement, P3)

Description

[nicolas m]

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:48.0) Gecko/20100101 Firefox/48.0
Build ID: 20160823121617




Expected results:

OpenType 1.8 introduces Font Variations, a parametric type design system.

References:
* https://medium.com/@tiro/12ba6cd2369
* http://blog.typekit.com/2016/09/14/variable-fonts-a-new-kind-of-font-for-flexible-design/
* https://opensource.googleblog.com/2016/09/introducing-opentype-font-variations.html
* https://www.microsoft.com/typography/otspec180/otvaroverview.htm

Is this possible to implement support for these new features in Gecko?

Comment 1

[Jonathan Kew [:jfkthame]]

It'll be dependent on support in the font rasterizer we use, which varies depending on the platform. So this may become possible at different times on Linux/Android (depending on Freetype support), Mac OS (CoreGraphics) and Windows (DirectWrite).

There's also the issue of the CSS support for font variations (currently under discussion).

We should probably consider this an overall meta-bug for variation-font support, and file dependent bugs for the individual work items that will be needed: probably one for each platform/rasterizer backend, and one (or more) for the CSS side.

Comment 2

[Jen Simmons [:jensimmons]]

Variation Fonts are getting a lot of attention from web designers, typographers, and font companies. They are all very excited about it, especially the performance implications.  

Chrome is already all over this: https://twitter.com/typo_labs/status/850728396099383297

And imo, this is one that will gather steam quickly, and yet, developers won't use it until it's in most browsers — putting extra attention and pressure on any browser that doesn't support it.

Comment 3

[Jen Simmons [:jensimmons]]

Any news on when we plan to implement Variable Font support?

Comment 4

[jason]

When these flags are set, variable fonts seem to work quite well. I realize there must be more to the story; it would be good to know if there is any way to help/find more support for getting this out from behind the flags.

```
Set layout.css.font-variations.enabled = true.
Set gfx.downloadable_fonts.keep_variation_tables = true.
Set gfx.downloadable_fonts.otl_validation = false.
```

Comment 5

[Jonathan Kew [:jfkthame]]

Currently, they're only implemented on macOS. We're working on adding support on other platforms, but it's some way off yet.

Comment 6

[Liz Henry (:lizzard) (relman/hg->git project)]

Added this to 62 nightly + beta release notes and it sounds like we are on track to ship this in 62.

Comment 7

[will69]

You might want to change the release notes to indicate that variable fonts do not (yet?) work on Windows 7, as this is still the dominant desktop operating system for Firefox users, according to https://data.firefox.com. The current wording will raise expectations and will leave people disappointed. (Especially since variable fonts do actually work in Chrome on Windows 7.)

Comment 9

[kkaufmann]

Forgive me if it's already been covered:

I'm building out a new site, and found that WOFF2 variable fonts in OTF flavors work fine in Webkit browsers, but not in Gecko/Firefox, with no errors given. Luckily there are TTF flavors for the same family, but know this may not be the case going forward.

Is this a known bug?

Comment 10

[jeremyfairbrass]

I've also encountered the same problem that @kkaufmann mentioned above: Firefox doesn't seem to support OTF flavours of WOFF2 variable fonts, although they work fine in Chrome/Edge.

For example (in case anyone wants to reproduce this): the Source Sans 3.046 font here:
https://github.com/adobe-fonts/source-sans/releases

This font family includes variable WOFF2 fonts in both TTF and OTF flavours, using these file names:

• SourceSans3VF-Roman.ttf.woff2 → TTF
• SourceSans3VF-Roman.otf.woff2 → OTF

If I use the TTF version, it loads correctly in Firefox. But if I use the OTF version, it does not load correctly in Firefox. Firefox instead falls back to the next font family defined in the font-family CSS property for the respective web page text.

Fortunately with this particular font family, both versions are provided. But it's certain to be the case that other font designers might only provide an OTF version of a WOFF2 variable font, and not a TTF version.

FYI, I'm using 64-bit Firefox 92 on Windows 10.

Any chance this can be fixed/improved?

Comment 11

[Jonathan Kew [:jfkthame]]

I think this is essentially a Windows limitation: the DirectWrite font system does not fully support CFF2 fonts. (Note that some of the Adobe font releases have an explicit warning about this, e.g. see https://github.com/adobe-fonts/source-han-sans/releases/tag/2.004R. Perhaps this should be included on all their font release pages; it seems a bit haphazard at the moment.)

Blink-based browsers like Chrome work around this by including a copy of FreeType built in to the browser, and using this instead of DirectWrite to render such fonts. Of course, this doesn't come for free; there's a code size and maintenance cost to consider.

Doing the same thing in Firefox would be bug 1403299.

Comment 12

[jeremyfairbrass]

(In reply to Jonathan Kew (:jfkthame) from comment #11)

Thanks for explaining that! Do you think it's likely that FreeType will ever get added to Firefox in the future? It looks like bug 1403299 has been sitting dormant for the past few years. ;)

Comment 13

[David Lawrence [:dkl]]

Changing qe-verify? to qe-verify+.