[css-color-5][css-images-4] Are these features ready to ship?

[jensimmons]

How finished are the specifications for these features?

From Color 5:

• color-contrast()
• color-mix()
• Relative Color Syntax

From Images 4:

• Non-sRGB interpolation of CSS Gradients

They are currently part of Interop 2022... can browsers ship them? Or are the specs still changing too much?

[jensimmons]

Spec links:
https://drafts.csswg.org/css-color-5/#colorcontrast
https://drafts.csswg.org/css-color-5/#color-mix
https://drafts.csswg.org/css-color-5/#relative-colors
https://drafts.csswg.org/css-images-4/#linear-gradients

Relevant: #7302

[css-meeting-bot]

The CSS Working Group just discussed color functions and RCS.

The full IRC log of that discussion

<TabAtkins> Topic: color functions and RCS
<bkardell_> astearns: did we talk about a day to meet up next week on selectors 4? doing it on the list?
<TabAtkins> jensimmons: These are all part of Interop2022, are they ready to ship? ARe specs good enough, or are they unstable?
<astearns> github: https://github.com//issues/7310
<emilio> q+
<astearns> ack em
<TabAtkins> emilio: I'd love to ship some of these, but there's a lot of open questions
<TabAtkins> emilio: I don't think there's any complete impl of these features.
<TabAtkins> emilio: WebKit implements a bunch, but doesn't support currentcolor at all. Gecko also has trouble with currentcolor.
<TabAtkins> emilio: There's some question about resolution timing taht I filed last week.
<TabAtkins> emilio: So don't think things are quite ready to ship yet.
<TabAtkins> jensimmons: So question really is if the spec is gonna significantly change after shipping happens.
<TabAtkins> jensimmons: I think your issue highlights that some things still need to be defined. Maybe we can make this a prio to finish the spec?
<TabAtkins> emilio: Think that would be great. Haven't been working actively, been spending free time on it.
<TabAtkins> emilio: I can tell from Firefox usage - we enabled color-mix() in trunk and it's used extensively, over a thousand uses immediately.
<TabAtkins> emilio: So I think it would be great to prio.
<TabAtkins> astearns: So we're at time, please put your thoughts in that issue.
<TabAtkins> astearns: AGree I'd like to see one complete impl before making the decision that it's shippable.
<TabAtkins> fantasai: Sounds like this isn't ready to ship *yet*, but we should try to get it there soon.
<TabAtkins> emilio: What I"d love is to avoid interdependencies on these features.
<TabAtkins> emilio: weinig commented that they'd prefer color-mix() to serialize with new color syntaxes unconditionally; i'm not opposed to that, but it requires us to have new colors to ship color-mix(). Makes me a little sad because it's more work to get this in the hands of authors, but they feel strongly about that.
<TabAtkins> emilio: It'd be great to work out a way to minimize interdependencies so we can ship incrementally.

[fantasai]

Sounded to me like RESOLVED: Not Yet

[svgeesus]

emilio: weinig commented that they'd prefer color-mix() to serialize with new color syntaxes unconditionally; i'm not opposed to that, but it requires us to have new colors to ship color-mix(). Makes me a little sad because it's more work to get this in the hands of authors, but they feel strongly about that.

I agree with @weinig on this

[svgeesus]

(I was on vacation for a week, sorry for the delay in responding)

How finished are the specifications for these features?

From Color 5:

color-contrast()

Pretty stable, has not changed much recently. Depends on (not very good, but stable) WCAG 2.1 contrast algorithm. Could be updated in the future to use the WCAG 3.0 algorithm as an explicit option, but that spec is far from setled and this future upgrade should not affect shipping it now.

color-mix()

Little churn now the syntax has stabilized. Depends on CSS Color 4 for color interpolation, which is also pretty stable.

Relative Color Syntax

Also pretty stable now.

From Images 4:

Non-sRGB interpolation of CSS Gradients

Depends on CSS Color 4 for color interpolation, which is also pretty stable.

They are currently part of Interop 2022... can browsers ship them? Or are the specs still changing too much?

The specs are not changing very much, mainly on points of detail or better wording. I firmly agree with these choices for Interop 2022 and hope that Chromium and Gecko are inspired to catch up to the fine implementation of these features in WebKit.

[fantasai]

Could be updated in the future to use the WCAG 3.0 algorithm as an explicit option, but that spec is far from setled and this future upgrade should not affect shipping it now.

My understanding is that the WCAG 3 algorithm is way better than the WCAG 2 algorithm, so making WCAG 3 the "opt-in" version would be kinda sad. How unstable is that algorithm itself (as opposed to WCAG 3 in general), and would it make sense to use it anyway?

[svgeesus]

How unstable is that algorithm itself (as opposed to WCAG 3 in general), and would it make sense to use it anyway?

That algorithm specifically is very contentious, is still being frequently modified, and does not seem to have consensus. People are deploying (various different revisions of) it in the wild.

[LeaVerou]

I will also point out that none of the editors of Color 5 (@svgeesus, me, @argyleink, @una) have been in that call, so it seems rather weird that the maturity of our spec was discussed and decided on in our absence. The reasonable thing would have been to punt it until at least ONE editor is on the call.

As Chris points out, most of these features are pretty stable, and have had experimental implementations in WebKit for a while. If you disagree, please point out specific issues, not just some general feeling. If you believe there are issues that have not been resolved but can't point to a GitHub issue, then create one! (e.g. I saw some concerns about currentColor — is there a GitHub issue about them??)

[svgeesus]

and have had experimental implementations in WebKit for a while.

Yes, in Safari since TP 122 so more than a year ago; and also ongoing implementation work in Gecko since Firefox 88. Both behind a flag. There is an associated Chromium issue, not clear if that means implementation is ongoing.

I agree there are specific issues being discussed, in particular regarding resolving color-mix() and color-contrast() or percentage normalization in color-mix(); in fact these are typical implementer feedback questions which one would expect to get in CR.

[svgeesus]

I saw some concerns about currentColor — is there a GitHub issue about them??

I think that is

• [css-color-5] What should the behavior of the CSS Color 5 color functions be when passed currentcolor as <color>  #6168
• [css-transitions] Define interpolation of the currentcolor keyword #445

which were somewhat simplified by the resolution to

• [css-color] [css-color-adjust] Make system colors fully resolve (but flag they were system colors) thus reversing the resolution of #3847 #6773

[jensimmons]

I will also point out that none of the editors of Color 5 have been in that call, so it seems rather weird that the maturity of our spec was discussed and decided on in our absence. The reasonable thing would have been to punt it until at least ONE editor is on the call.

Sorry you weren't able to be there. We only talked about this for 2-3 minutes. Nothing was “decided”. I asked because we want to know if the specs are mature enough to start shipping.

Really it's a two part question:

• For the editors, do you think browsers should start shipping? Or do you know of issues that need to be resolved first? Or edits you've been meaning to make?
• For other implementors — do you have any objections to the current specifications? Anything you want to change or debate further before we all start shipping?

The only decision here to make (in this issue) is for each browser team to decide if they want to ship now, given the responses to these questions. Or hold for further debate and potential upcoming changes.

If there are any issues left to debate or resolve, can we do so quickly? Let's remove any blockers, so we can get this technology into the hands of web developers.