Should ebutts:multiRowAlign be deprecated?

[palemieux]

Depends on w3c/ttml2#238

[css-meeting-bot]

The Working Group just discussed Should ebutts:multiRowAlign be deprecated? #277, and agreed to the following resolutions:

• RESOLUTION: Do not deprecate ebutts:multiRowAlign, prohibit inline block, leave TTML2 as is.

The full IRC log of that discussion

<nigel> Topic: Should ebutts:multiRowAlign be deprecated? #277
<nigel> github: https://github.com//issues/277
<nigel_> nigel: The idea here is that the TTML2 semantics of setting textAlign on nested elements
<nigel_> .. does the same thing as multiRowAlign and therefore we no longer need multiRowAlign.
<nigel_> .. But the mapping to CSS doesn't work.
<nigel_> glenn: Elika suggested using display:inline-block
<nigel_> cyril: CSS would like to understand the use cases and constraints rather than receiving a solution.
<nigel_> pal: That would be the multiRowAlign case.
<nigel_> glenn: I think there is no meaning of alignment in span in CSS because there's no extra
<nigel_> .. space, unless you set width explicitly.
<nigel> pal: display:inline-block only works in CSS if you have explicit line breaks.
<nigel> .. A question for CSS is if that is a bug in browsers or by design.
<nigel> .. If they say it is by design then we can ask how to proceed.
<nigel> glenn: I looked at this before and concluded that the spec doesn't support the browser
<nigel> .. implementations.
<nigel> cyril: Can we do it in two steps? Do we agree the semantics of multiRowAlign need to be in
<nigel> .. TTML2?
<nigel> pal: This is in use
<nigel> glenn: It is defined in TTML2 and implemented in at least one implementation.
<nigel> cyril: Is this a case where it is defined in TTML2 with a different syntax.
<nigel> glenn: It requires more content work to do this in TTML2 because you have to create
<nigel> .. nested spans and setting inline-block. There's a transcoding issue but no namespace issue.
<nigel> cyril: So there is a way to do it. Does this fall into the category we agreed before in the
<nigel> .. deprecation model?
<nigel> pal: I think it falls into the same category as linePadding that we just did.
<nigel> .. It would be a stronger argument if there were a direct mapping to CSS.
<nigel> .. The approach in TTML2 has a different syntax from what is in wide use in IMSC1.
<nigel> glenn: And there's a question about mapping into CSS anyway.
<nigel> nigel: And the TTML2 syntax is more verbose.
<nigel> glenn: A useful side effect of inline block is to create horizontal and vertical struts, by
<nigel> .. setting ipd and bpd on inline blocks.
<nigel> nigel: Can you set ipd and bpd to use all the available space?
<nigel> glenn: Yes you can use allocation to use as much space as possible.
<nigel> atai: I agree for authors this is more complex. Is it more complex for implementations too?
<nigel> .. For presentation processors it is more complex.
<nigel> pal: For sure.
<nigel> atai: I possibly would vote the same way as for linePadding but for a different reason, to
<nigel> .. exclude from TTML2 and just include in IMSC 1.1. I am not sure how often this feature
<nigel> .. is used in practice. multiRowAlign is widely used in legacy contexts but only works because
<nigel> .. of the constraints of those legacy contexts.
<nigel> pal: I would agree to keep this in IMSC 1.1 and ask CSS how to do this.
<nigel> glenn: It took 70 lines of code to implement multiRowAlign in TTPE, which translates
<nigel> .. it into textAlign in TTML2 with inline block. That's fully tested.
<nigel> s/TTPE/TTX
<nigel> nigel: So you would not deprecate multiRowAlign even though it can be done in TTML2?
<nigel> atai: correct
<nigel> pal: It is extra work, and if we think it may not be used, then we should not use it.
<nigel> .. I would not allow inline-block in IMSC 1.1
<nigel> nigel: Is inline block needed anywhere else?
<nigel> glenn: There are edge cases that need inline blocks using struts.
<nigel> nigel: What are those cases? Do we expect them to be used?
<nigel> glenn: I have to check but I believe I am using it for rubyReserve.
<nigel> nigel: So you're mapping one TTML2 syntax to another?
<nigel> glenn: Right
<nigel> nigel: So there's no authorial requirement to use inline blocks?
<nigel> glenn: Correct. The requirement came from SMPTE digital cinema to specify a varying
<nigel> .. width, which can only be done with ipd.
<nigel> pal: Digital Cinema isn't driving the requirement for IMSC
<nigel> RESOLUTION: Do not deprecate ebutts:multiRowAlign, prohibit inline block, leave TTML2 as is.

[nigelmegitt]

Netflix has objected to this Resolution, requesting:

• Mark ebutts:multiRowAlign as deprecated in IMSC 1.1
• Add an exactly equivalent style attribute to TTML2 and permit that in IMSC 1.1

[css-meeting-bot]

The Working Group just discussed Should ebutts:multiRowAlign be deprecated? imsc#277, and agreed to the following resolutions:

• RESOLUTION: Do not deprecate ebutts:multiRowAlign (and also remove it from TTML2 until a CSS compatible mechanism is available)

The full IRC log of that discussion

<nigel> Topic: Should ebutts:multiRowAlign be deprecated? imsc#277
<nigel> github: https://github.com//issues/277
<nigel> RESOLUTION: Do not deprecate ebutts:multiRowAlign (and also remove it from TTML2 until a CSS compatible mechanism is available)