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

From: <bugzilla@jessica.w3.org>
Date: Mon, 14 Dec 2015 18:34:33 +0000
To: www-international@w3.org
Message-ID: <bug-28257-4285-aWoUhFGBBF@http.www.w3.org/Bugs/Public/>

--- Comment #22 from Richard Ishida <ishida@w3.org> ---
i read through the thread again.  Here is my summary of the situation as i
understand it (trying to bring the threads together in one coherent sum-up). Of
course, please point out where i have misunderstood things.

[1] I think we have established that the base direction of the text (ie. the
inline direction of the text contained inside a cue box) should have no affect
on the placement of the frame of the cue box.  In respect of base direction,
the cue box as simply a receptacle into which text flows.  The cue text may be
rtl or ltr, or a mixture of the two, but the cue box stays where it is.  This
makes sense, since most of the time a positioned cue box is positioned to match
the geometry of what is going on behind it (eg. to avoid overlapping something,
or to position relative to a speaker, etc.)

[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).

[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'.

[4] In most cases, as Philip says, if you position the text on the screen it is
to avoid overlapping something, or to appear relative to something (eg. the
speaker on the video behind). What appears in the background is unlikely to
change based on the language of the webvtt script. 

[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

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Received on Monday, 14 December 2015 18:34:38 UTC

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