[css-ruby] alternating sides for ruby-position

[frivoal]

Several people have suggested (Xidorn, Roland) that there should be a value (possibly called auto, or alternate),
that alternates between 'over' and 'under' when the ruby has multiple levels of interlinear annotation.

My [Xidorn’s] proposal is: This value is not computed to anything else. And during the
positioning, this value is equal to "over" for rtc in odd indexes, and "under" for rtc in even indexes.

Overall, it sounds reasonable to [fantasai], but I think we should have a way to specify the first level, rather than always being over. Maybe [ over | under ] || alternate instead? Or something else?

This value should probably be the initial value.

[jensimmons]

Could you add a code example to this, @frivoal ? Of what's being proposed.

[frivoal]

Here's an example. It's a little contrived in order to keep it in English for readability's sake, but the same idea would apply, and be more common, in Japanese or Chinese.

<ruby>
  <rb>S<rb>Q<rb>L</rb>
  <rtc><rt>Structured <rt>Querry <rt>Language</rtc>
  <rtc>Sequel</rtc>
</ruby>

This would look like this:

However, when you have two levels of ruby, the typical expectation is that instead of stacking up, they go on alternate sides, like this:

As the spec stands today, you can achieve it using ruby-position. For instance:

rtc:last-of-type {
   ruby-position: under;
}

That's cool, but:

1. You have to ask for it explicitly, even though it's the most commonly desired outcome
2. The selector in the example above is specific to the markup pattern used in that example, and no generic selector that would work across all pages can be written (rtc and rt elements can, and typically are, omitted in most situations)

However, if instead of over, the initial value of ruby-position was alternate (a keyword we'd need to introduce), it would work outside of the box, without a need for manually opting into it.

The other variant being proposed is instead of over | under | alternate, we could have [over | under ] || alternate. alternate or over alternate would do the same as the above example (first annotation over, then alternate), while under alternate would put the first annotation under, and then alternate.

[css-meeting-bot]

The CSS Working Group just discussed [css-ruby] alternating sides for ruby-position, and agreed to the following:

• RESOLVED: Add an alternate value which is the initial value

The full IRC log of that discussion

<dael> Topic: [css-ruby] alternating sides for ruby-position
<dael> github: https://github.com//issues/5971
<dael> florian: 3 values, focus on over and under. Default is over
<dael> florian: If you have 1 layer it goes over. If 2 they both over and stack.If want one over one under need selector
<dael> florian: People sometimes want to stack, but majority is when you have 2 layers (3 almost not done) people want one on each side
<dael> florian: Separate selectors is annoying, esp given markup has anon boxes
<dael> florian: Prop is default value is auto or alternate which is over iwth 1, over and then under with 2, and continue alternating with more
<dael> myles: Didn't realize prop changing initial value. I think we have ruby in books which is scary.
<dael> myles: Separating changing initial value from the new propery is good
<dael> fantasai: Don't think you support multi-level
<dael> myles: Doesn't effect nested. Multi level ruby in same lement only?
<dael> fantasai: Yes.
<dael> myles: Then, now that I understand, if you tried to give this to use we would have longer ruby text on top
<dael> fantasai: Not sure, haven't loaded it. It's a separate issue from if you display on top or bottom
<dael> myles: General compat concern
<dael> fantasai: Yeah. If you don't support multi-level in same ruby structure
<dael> florian: Problem is same no matter if value
<dael> myles: If we impl multi level without this we would turn 1 level to 2. With this we would turn it into 1 level about and one below
<dael> s/about/above
<dael> florian: If I remember your current impl, yes
<dael> astearns: myles resolve or investigate?
<dael> myles: Okay resolve. If things explose come back
<dael> astearns: Add an alternate value which is the initial value
<dael> RESOLVED: Add an alternate value which is the initial value

[astearns]

In reading the resolution I parsed alternate in the 'alternative' sense, and for a split-second worried that we had not specified what that alternative value was. Could switch perhaps be a better value name?

[frivoal]

you're alternating between sides, first over, then under, then over, then under… I think alternate is a better name for that than switch, so I'd rather stick to it.