[Not Release] [CSS] COLRv1 fonts supported

[hamishwillee]

Acceptance Criteria

• The listed features are documented sufficiently on MDN
• BCD is updated
• Interactive example and data repos are updated if appropriate
• The content has been reviewed as needed

For folks helping with Firefox related documentation

• Set bugs to dev-doc-complete
• Add entry to Firefox release notes if feature is enabled in release
  or
• Add entry to Firefox experimental features page if feature is not yet enabled in release

Features to document

Needs addition to experimental features page.

See Other for further research.

Related Gecko bugs

https://bugzilla.mozilla.org/show_bug.cgi?id=1740530

Other

So this allows you to apply colours, gradients etc to a font.

This is behind gfx.font_rendering.colr_v1.enabled. So minimally add to experimental features.

• Useful overviews here:
  • https://developer.chrome.com/blog/colrv1-fonts/
  • https://css-tricks.com/colrv1-and-css-font-palette-web-typography/
• Spec is here: https://docs.microsoft.com/en-us/typography/opentype/spec/ "OpenType® Specification Version 1.9"
• Cool easy test for what is supported here: https://pixelambacht.nl/chromacheck/

So this basically is support for using the colr v1 fonts in @font-face and `FontFace (i.e. using fonts that have color gradients etc). From the point of our existing docs we don't say very much about the different font tables and types of fonts and I don't think we need to. However we do need to indicate support for these features.

What has to be done is add the supported tables like colrv1 to BCD. Not all of them though, just the ones that can be feature checked in the @font-face src: descriptor's tech(...) syntax that FF is adding in #19833. This makes sense because tech() provides a fallback to a small subset, which are likely therefore to be the ones that have compatibility issues.

I don't think there is any particular need for docs on this though.

[hamishwillee]

@Rumyra I've done the basic review and converted to an issue. In summary, this is closely related to #19833. Support for the feature is behind a pref.

I'll probably take the BCD part of this but let's see how we go next month for the whole thing.

[Rumyra]

Yeh 💯 @hamishwillee - with the experimental features such as this I wonder whether the current month task is bcd & experimental features rel note - and we then put the issue back into the backlog (possibly close it temporarily) until it comes back to stable feature

[hamishwillee]

until it comes back to stable feature

Possibly. Depends a bit on @font-face src: descriptor's tech(...) feature - if that goes in "not" behind pref we might as well do the lot. Also sometimes it is good to document the stuff already in chrome because then adding the firefox stuff later is easy on shipping. Depends on bandwidth at the time.

Anyway, let's see how it goes :-)

EDITED: Note, this is independent of tech() but related. THe tech() lets you provide fallbacks based on whether a browser supports a feature, and color v1 support is one of those features you can fallback against.

[hamishwillee]

Status

• BCD -
  • Fontface openfont tables browser-compat-data#17645
  • extend to FontFace? - decided not to.
• Docs - none. There are few free/public fonts to try and this is still experimental. We should consider revisiting when FF releases this.
• Experimental features - FF105 OpenFont COLRv1 behind flag #20637
• Dev-docs complete

This is done. Fairly minimal - just BCD and experimental features. When this is released in FF we should consider an interactive example. Decided not to do it for now.