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[Bug 28257] [webvtt] start/end linked to left/right [I18N-ISSUE-422]

From: <bugzilla@jessica.w3.org>
Date: Tue, 15 Dec 2015 10:35:29 +0000
To: www-international@w3.org
Message-ID: <bug-28257-4285-Fr8w25FZ1G@http.www.w3.org/Bugs/Public/>
https://www.w3.org/Bugs/Public/show_bug.cgi?id=28257

--- Comment #23 from Simon Pieters <simonp@opera.com> ---
(In reply to Richard Ishida from comment #22)
> [2] The alignment of the lines of text within the cue box also has no effect
> on the position of the frame of the cue box (other than that you need to
> take into account the width of the box if you have some rtl and some ltr
> lines).

No, currently align:left and align:start will position the box on the left
(unless it is explicitly positioned somewhere). My proposal
https://github.com/w3c/webvtt/pull/273 is to let align:start/end be positioned
the same as align:center.

> [3] On the other hand, the *writing-mode* of the text will indeed affect the
> placement of the box.  (NB: writing-mode has *nothing* to do with base
> direction, it only refers to the direction in which the lines progress, one
> after the other.) The positioning of the cue box varies between vertical and
> horizontal coordinates, depending on the writing-mode direction. 
> 
> As i understand it, the spec currently uses `start` to abstract away from
> whether a position relates to left (for horizontal writing-mode) or top (for
> vertical writing-mode), and end to mean either right or bottom.  I'm not
> sure the terms start and end are apposite here, but that's a terminology
> issue – start in this case does not always mean 'left', it may also mean
> 'top'.

Yeah, but this is pretty inconsistent with CSS, as is pointed out in comment 9.

> [5] On the other hand, Addison i think is saying that, in cases where you
> are not positioning the text relative to what's happening behind it, but you
> *are* positioning it, you may want the position to be influenced by reading
> direction.  I think Philip would argue that in such cases there should be no
> positioning, and the text should be centred in the full width of the screen
> (the default), so as to reduce line breaking.
> 
> If Addison's use case holds, then i believe we may need to use words along
> the lines of start and end for horizontal text that are related to the
> script direction, but i think it relates to the language of the webvtt
> annotations *as a whole* (ie. for an arabic transcription do the mirroring,
> but do it throughout - the position is still not affected by the base
> direction of the text inside the box). However, i can't see how that use
> case would in practice be relevant for cue boxes for which the writing-mode
> is set to vertical – i think the necessary keywords would be relevant for
> horizontal writing-mode only.

I think it's more a reasonable expectation that "start" position alignment
would react to LTR/RTL, as it does in CSS, and as the 'align' setting does,
instead of meaning line-left. The PR renames these to left and right, since
they map to align:left and align:right sides.

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Received on Tuesday, 15 December 2015 10:35:32 UTC

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