[css-text-decor-4] Consider adding a third value (skip?) for text-decoration-skip-ink.

[emilio]

https://drafts.csswg.org/css-text-decor-4/#text-decoration-skip-ink-property right now only defines auto | none, where auto is meant to skip.

It seems reasonable to be able to do per-platform ink-skipping considering the defaults of a platform or a language (e.g., don't skip by default on Windows), while allowing authors to explicitly skip when they want.

Would it be reasonable to make the property take a third value to explicitly skip, and give more freedom to the UA for the auto value?

[litherum]

I'd like to hear Microsoft's position on enabling ink skipping by default.

[css-meeting-bot]

The Working Group just discussed Consider adding a third value (skip?) for text-decoration-skip-ink.

The full IRC log of that discussion

<dael> Topic: Consider adding a third value (skip?) for text-decoration-skip-ink
<dael> github: https://github.com//issues/2818
<dael> Rossen: astearns you added this from the F2F. I wanted to hear from Amelia or myles or anyone involved
<dael> myles: This is asking for a distinction between off/on/do what platform does. For us on and do platform is the same. Proposal asks for explicit on. I wanted to knwo what other vendors thought about skipping on by default
<dael> fantasai: I don't think it's by default. Request is a value, doesn't mean we change initial. Initial is auto.
<dael> Rossen: Do we need auto?
<dael> fantasai: Yes. Wanted to allow UA to do what it felt like.
<dael> myles: Cool if all browsers decided default was do skipping so we could have 2.
<dael> Rossen: Our position is we just finished re-write inline layout. ink-skipping was on my shortlist, but that shortlist wasn't short so we didn't get to it. As a targetted behavior we'd want on by default once we have it. Just like w e enable kerning by default. Doable, not super concerning for perf.
<dael> myles: Sounds like you're okay with 2 values
<dael> Rossen: Yes
<dael> myles: We are also happy with 2
<dael> Rossen: Having said that there's now ay to force it. If platform supports but if i t decides on that device it disables you can't force it.
<dael> myles: When you produce a product that can have that behavior we can re-open?
<dael> Rossen: Fine.
<dael> Rossen: Is Amelia on?
<fantasai> s/Amelia/Emilio/
<dael> dbaron: I don't think xidorn wanted it on for all
<dael> myles: Do you remember reasons?
<dael> dbaron: I think some w as related to what he saw as default on platform. Maybe windows primarily.
<dael> dbaron: Don't remember that well. Underlying was xidorn wasn't comfortable with on by default for all.
<dael> myles: Maybe let this go into issue and ask him to comment in issue?
<emilio> Rossen: I'm on IRC fwiw (can't get on the call today :()
<dael> fantasai: Yeah. Can also take up on Sept 5 call
<dael> myles: Sounds good
<dael> Rossen: Sounds reasonable.
<dael> Rossen: Let's stop here and move on.

[astearns]

@upsuper could you look at the discussion above and comment?

[upsuper]

I don't recall my rationale... actually I don't recall whether it's me or emilio wanted that.

Anyway, I think I'm fine with auto | none. I'm actually a bit concerned about all having unfortunate behavior for scripts which shouldn't have ink-skip applied by default (or, if we still exclude some scripts, why would we call it all?).

[emilio]

I think the rationale was that some platforms' default ink-skipping behavior is not to ink-skip.

Having only auto or none means that UAs can't differentiate between when the author has explicitly requested ink-skipping or not, so can't be smart about when to ink-skip to match platform conventions. Ideally we'd have an opt-in value, an opt-out value (none) and a "do the default thing", which is auto.

@jfkthame was the person that initially pointed the per-platform difference to me, I suggested the third value.

[css-meeting-bot]

The CSS Working Group just discussed Consider adding a third value (skip?) for text-decoration-skip-ink, and agreed to the following:

• RESOLVED: text-decoration-skip-ink only takes 2 values, none and auto with auto being default
• RESOLVED: add normative text that states the auto property forces the UA to add the appropriate level of skipping

The full IRC log of that discussion

<dael> Topic: Consider adding a third value (skip?) for text-decoration-skip-ink
<dael> github: https://github.com//issues/2818
<dael> Rossen_: We wanted xidorn on the call for this
<dael> Rossen_: Who wants to summerize?
<dael> fantasai: This is Text-decoration-skip. Issue is we had resolved on auto and none values, but there wasn't an on value
<dael> fantasai: If auto means platform that will in some cases not skip. If author wants skipping being able to say on should be separate. Otherwise auto means on and loses ability to be auto.
<myles> q+
<dael> fantasai: Proposal is add a new value that means please skip. I propose skip-ink for a name
<dael> fantasai: Reason is we might want shorthand in the future so skip values can be combined without ambig
<tantek> regrets+
<myles> is Xidorn here? The whole reason we're discussing this again is to get his input
<dael> florian: sgtm. I remember related topics were discussed, tried to look. May have missed something, but found that if we have this it should not skip on strike-through. Agreed never skip on strike-through
<dael> fantasai: right
<xidorn> myles: I am
<dael> florian: Other then shorthand convo couldn't find anything against this
<dael> xidorn: myles asked for my opinion. I commented in the github and I don't think I'm the one that raised this. Prob. emilio. I didn't have issue with auto and none but having skip-ink is fine. As long as we don't use 'all' or something
<myles> can we come back to to this when my micorophone is working?
<dael> Rossen_: myles, what would you like to say and why can't we hear you?
<dael> myles: If we wanted 3 values it would be because obey platofrm and do skip-ink would be distinct.
<dael> myles: Last time we discussed MS said wanted this on by default. If yes all major platforms would have skip-ink same as auto so if yes we donn't need 3rd value
<dael> fantasai: If we have on and off as 2 values auto should be clear what it does
<dael> myles: Happy to call what you want
<dael> xidorn: Auto still makes sense. It can depend on how impl does. Impl can decide what script to skip.
<dael> fantasai: If you skip on some and not others it's not on.
<dael> myles: That's true because typographical sense. Some scripts should never skip
<dael> Rossen_: There are casess to optimize for not skipping. Like for particular font size. There's diminishing retern for skipping on smaller font sizes.
<dael> Rossen_: If I get xidorn that's a bit more we can take different heuristics on when to skip but in general skipping in auto should be skipping. Is that right xidorn ?
<dael> xidorn: yeah
<dael> fantasai: If there's any magic under the scenes that's auto and that's not eq. to on. On is always and if author wants they should get it
<dael> myles: Opposite view is typographically the on value is bad to use and no one should use it
<dael> Rossen_: And for back compat in cases...for platforms that don't have feature impl then auto is great for default
<dael> florian: We're trying to resolve now is that the auto can mean different levels of skipping but not no skipping at all. Is that what we're trying to say?
<dael> Rossen_: Kind of. And for a platform that doesn't support skipping
<dael> florian: Sure, then you don't support the value so no skipping is a fallback
<dael> fantasai: There are cases where skipping and not skipping the heuristic of the browser might not be what the person wants. If you have arabic and position underline so it's exactly with the dots then not skipping becomes and issue. I don't htink it makes sense to say the UA can decide but the author can't
<dael> florian: The always-on auto is bad for a universal selector but if you're smart if can be fine
<dael> AmeliaBR: Agree with fantasai there should be ability of authors to override heuristics. Maybe one solution is to make it clear the value is an override or force by the name. Make it clear it's not what you should normally use.
<dael> florian: I think auto and skip-ink are reasonable
<dael> Rossen_: let's see if can resolve on...
<dael> florian: non, auto and skip-ink
<dael> s/non/none
<AmeliaBR> So it would be `text-decoration-skip-ink: skip-ink` ?
<florian> AmeliaBR: yes, for the sake of when we have a short hand of many different kinds of skipping
<dael> Rossen_: Proposal: 3 value property which is text-decoration-skip-ink: none|auto|skip-ink(or skip)
<florian> s/short hand/shorthand/
<dael> Rossen_: We we care about skip/skip-ink or can we ignore for now?
<dael> fantasai: I think resolve now
<dael> myles: Shouldn't be a value where browser doesn't have ability to make your text not ugly
<dael> florian: Don't you think author might know better in some cases?
<dael> Rossen_: Author doesn't know device and settings so it's hard to predict this
<dael> Rossen_: I sympathize with myles on this one
<dael> Rossen_: Start with auto and none and if when this takes off and there's a huge degree of requests for skip-ink we can add it. Removing it is harder.
<florian> works for me. If we have two values, it should be none and auto.
<dael> Rossen_: So back to the two values none|auto with auto default
<dael> myles: Great idea. If goal is let users fix browser heuristics we'll hear from users if heuristics are no good. Then it's a great time to add the value
<dael> xidorn: I agree with myles . Oncce we have more feedback from users on use cases we may revise even differently then three keywords
<dael> Rossen_: Objections to resolve text-decoration-skip-ink only takes 2 values, none and auto with auto being default
<dael> RESOLVED: text-decoration-skip-ink only takes 2 values, none and auto with auto being default
<dael> florian: Do we try and craft spec wording to mean that auto is for typographic smart, but not do nothing. not supporting we don't need to take into definition of property
<AmeliaBR> Current definition is `auto`: UA should skip over where glyphs are drawn
<dael> Rossen_: Levels of not supporting. You support it but for some devices you want this offer for battery.
<dael> florian: If you use @supports text-decoration-skip-ink: auto can you expect some level of skipping?
<dael> Rossen_: I think answer should be yes
<dael> Rossen_: myles ?
<dael> myles: Auto is meant ot let browsers have freedom. Spec can desc freedom
<dael> florian: Freedom, but not to not skip at all
<dael> myles: That's fair
<dael> fantasai: Needs to be clear. Currently initial value means you can not skip. If we say that's not possible we should be explicit about that
<dael> myles: My thought is if MS thinks this is right we can put it in spec
<dael> Rossen_: Once we have support for the property having it on by default is the path forward. We would support that
<dael> Rossen_: Additional resolution to make those edits?
<myles> s/auto property/auto value/
<dael> Rossen_: Objections to adding normative text that states the auto property forces the UA to add the appropriate level of skipping?
<dael> RESOLVED: add normative text that states the auto property forces the UA to add the appropriate level of skipping

[upsuper]

It just occured to me that browsers may want not to skip ink for certain decoration style as well, for example, Safari doesn't skip ink for wavy lines (and although Chrome does, I think it'd probably be better for them not to do so as well). Would that affect the proposed normative text for auto?

[litherum]

I think this is a duplicate of #4277.