Neither outside nor auto feels like a good name for this in general... Maybe we can add a ruby-position-last for this usage just like text-align-last?

@upsuper Seems like overkill. Not really something that needs to cascade independently afaik, doesn't have complex interactions with anything... Adding a value makes much more sense than adding a property.

I think outside or outer is sufficiently clear, personally. The main concern I have is “What is the last line?”.

For justification we use the last line before any forced break. For text-indent we use the first line of a non-anonymous block. I have no idea what TTML’s markup model would require here...

I don't think they are clear, tbh. over and under are relative to the base text, but outer or outside in this context is relative to the whole paragraph. It would be great if there is some specific name for this behavior...

I also thought about the last line, and that feels non-trivial to implement and may add some complexity, because ruby-position is a inline-level property, and is handled in the progress of laying out a line. You cannot know whether a line is the last line until it is fully laid out, which means we may need to reprocess the line if we have such ruby position. This may not be that hard but does seem to be more complicated than its usefulness...

If we change it to only do different thing on first line, that would probably make it easier to implement.

“What is the last line?”

@skynavga @cconcolato @palemieux ping!

The TTML2 spec does answer the question:

<annotation-position> says:

outside

Equivalent to before for (1) the only line area of or (2) the first line area of the last block area generated by a p element which contains annotated text; otherwise, equivalent to after.

So I think the answer is it is based on the line areas generated by layout of the base text, with ruby and text emphasis then inserted in the appropriate position as a later step.

The Working Group just discussed Add over-most-under-last value to ruby-position & text-emphasis-position for captioning.

@nigelmegitt @palemieux would using ::first-line to set before work for this case?

Hi @nigelmegitt and @palemieux, CSSWG wanted to know if it would be acceptable to just use

p { ruby-position: under; }
p::first-line { ruby-position: over; }

and if not, why not. :)

@nigelmegitt @palemieux @skynavga @cconcolato Can i just check that the wording in the TTML spec is correctly?

Equivalent to before for (1) the only line area of or (2) the first line area of the last block area generated by a p element which contains annotated text; otherwise, equivalent to after.

The case for a single line is fine. The case for two lines (the most likely scenario) is fine too. I was under the (quite possibly mistaken) impression that in the case of 3+ horizontal lines, ruby would appear above the text except for the last line only, where the ruby would be shown below.

Btw, the Netflix requirements at https://medium.com/netflix-techblog/implementing-japanese-subtitles-on-netflix-c165fbe61989 say that there should never be more than two lines (because ruby should never appear between lines). So it doesn't help clarify.

@r12a for the 3+ case, we changed the spec to use after (below) for non-first lines; this was done to ensure we could map this to CSS using ::first-line;

also, regarding the NFLX requirements regarding no more than two lines, that is the NFLX style convention, but does not necessarily apply outside NFLX; one should read that document as one input providing guidance rather than universal requirements; in any case, we need the spec to handle the case where more than two lines are created during layout, which is something the author cannot predict due to variations in actual fonts on the client;

@fantasai @astearns yes, it looks like using ::first-line in the way suggested at #2998 (comment) and #2998 (comment) would work.

As @skynavga pointed out, the TTML2 spec was changed after this issue was raised in a way that enabled exactly this hypothetical solution. I've confirmed this offline with @palemieux.

The change needed is to allow ruby-position to apply to ::first-line.

Ruby Layout Module Level 1 explicitly excludes this currently, and the Pseudo-Elements Module Level 4 ::first-line specification is consistent with that because it does not list any ruby properties.

By the way, this is analogous to text-emphasis-position which does apply to ::first-line. It seems obvious to me that the same mechanism should be used for positioning ruby as for positioning text emphasis.

OK, I've made the edits for this. There's a tangential follow-up for the CSSWG in #4642 but I think this issue itself is closed.