Re: TTML2 anonymous inline region creation

As I noted in my last reply on this thread, the anonymous region mechanism
is no more than a (reduced) syntactic shorthand for an inline region. This
was done to support existing, but non-standard usage that came out of a
mis-interpretation of what styles applied to what elements. There should be
no expectation that this shorthand can be as expressive as its referent,
namely as the equivalent inline region. Conclusion: if you want the full
expressive power, use an inline region.

On Wed, Oct 21, 2015 at 3:20 AM, John Birch <John.Birch@screensystems.tv>
wrote:

> I have the expectation that the end effect would be as Nigel described
> (regardless of mechanism).
>
> I.e. I would expect that the ‘anonymous region’ that is actually created
> would behave and be defined with exactly identical attribute properties to
> the region strictly associated with the p element (with the replacement of
> the specified attribute(s). *However, due to my prolonged exposure to
> TTML, I suspect that this is not always the case – and only detailed
> reading and comprehension of the full standard, and some careful thought,
> would tell me why and when this might not be the case...*
>
>
>
> So there is ‘one’ datum… ;-)
>
>
>
> J
>
>
>
>
> *John Birch | Strategic Partnerships Manager | Screen *Main Line : +44
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> *Visit us at BVE, London Excel, 23-25 February 2016, stand C20*
>
> *P* *Before printing, think about the environment*
>
> *From:* Glenn Adams [mailto:glenn@skynav.com]
> *Sent:* 21 October 2015 10:13
> *To:* John Birch
> *Cc:* Nigel Megitt; Timed Text Working Group
> *Subject:* Re: TTML2 anonymous inline region creation
>
>
>
>
>
>
>
> On Wed, Oct 21, 2015 at 2:43 AM, John Birch <John.Birch@screensystems.tv>
> wrote:
>
> I believe your proposal is more in line with users expectations.
>
> Viz: A user probably has the expectation that a region style attribute
> that is specified on a p element has an effect on the region that is
> associated with that p element.
>
>
>
> pure speculation, nothing to suggest this in fact
>
>
>
>
> Changing display align dynamically could be useful in the case of a
> simplistic document using a 'full screen' 'transparent' region. Similarly
> changing writingMode to support mixed Arabic / Latin might be useful.
> Consequently I don't think restricting the scope to specific style
> attributes is necessary... some cases might be somewhat limited in utility,
> but it is probably easier to apply the anonymous set concept to all region
> style attributes.
>
> Best,
> John
>
>
> John Birch | Strategic Partnerships Manager | Screen
> Main Line : +44 1473 831700 | Ext : 2208 | Direct Dial : +44 1473 834532
> Mobile : +44 7919 558380 | Fax : +44 1473 830078
> John.Birch@screensystems.tv | www.screensystems.tv |
> https://twitter.com/screensystems
>
> Visit us at
> BVE, London Excel, 23-25 February 2016, stand C20
>
> P Before printing, think about the environment-----Original Message-----
> From: Nigel Megitt [mailto:nigel.megitt@bbc.co.uk]
> Sent: 20 October 2015 15:48
> To: Timed Text Working Group
> Subject: TTML2 anonymous inline region creation
>
>
> All,
>
> Right now in TTML2 if a style attribute is specified on a p element that
> only has an effect on regions then an anonymous inline region is created.
> The style attribute inheritance chain is:
>
> >initial values -> anonymous region -> body -> div ... -> p -> span ...
>
>
> In considering how to fix tts:disparity it occurred to me that this isn't
> always what document authors might want or indeed expect.
>
> Another idea that I'm considering is: change from creating an anonymous
> inline region to creating an anonymous inline <set> element whose target is
> the region that applies to the element on which it applies and whose timing
> is coincident with the timing of the same element.
>
> In case of temporally overlapping elements that set the same style
> attributes to different values I would resolve the conflict using a
> begin-time-then-document-order rule, where last one wins.
>
> This would apply to the following style attributes that only have an
> effect on regions: tts:disparity, tts:extent, tts:origin, tts:position and
> tts:zIndex. I would probably exclude tts:displayAlign, tts:overflow,
> tts:showBackground and tts:writingMode because changing those on the fly
> would be weird.
>
> I'm just thinking this through right now, not definitively proposing it.
> The main thing I'm worried about is how the current solution interacts
> with issue-341 and issue-368. Even if we do go down the route of creating
> anonymous inline regions I imagine that authors will want a semantic like
> "just like a template region but with the specified style attributes
> differing", where the template region is the one that would have applied in
> the absence of the region-based style attributes on the p. That would also
> require a change to the inheritance chain, which would then be:
>
> Initial values -> specified region (if any) ... -> anonymous region ->
> body -> div … -> p -> span …
>
> Any thoughts on this appreciated, even if they're "Aargh don't change it
> now"!
>
> Nigel
>
>
>
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