Re: TTML2 anonymous inline region creation

one approach to this, an easier one IMO, is simply to leave the attributes
that trigger anonymous region to be those currently specified:
tts:{extent,origin,position}, and instead require the author to use
explicit inline regions if they wish to specify additional styles; after
all, anonymous regions are just syntactic sugar for an inline region, and
originally designed to handle the (non-standard) usage of specifying
tts:{extent,origin} on <p>

On Tue, Oct 20, 2015 at 10:22 AM, Nigel Megitt <nigel.megitt@bbc.co.uk>
wrote:

> From: Glenn Adams <glenn@skynav.com> Date: Tuesday, 20 October 2015 17:03
>
>
> On Tue, Oct 20, 2015 at 8:48 AM, Nigel Megitt <nigel.megitt@bbc.co.uk>
> wrote:
>
>> 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.
>>
>
> keep in mind that animation elements {animate, set} do not specify the
> associated element to which animation applies; rather, they are associated
> with an element either by context (in the case of an inline animation
> element) or by the use of the @animate attribute on a content element;
>
> so the content effectively points at the animation rather than the
> animation pointing at content (or region) elements;
>
>
> I think that's what I'm suggesting when I say that an anonymous inline
> <set> element is created.
>
>
>
>>
>> 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 is already dealt with in step (5) [animation styling] of [1]
>
> [1]
> https://dvcs.w3.org/hg/ttml/raw-file/tip/ttml2/spec/ttml2.html#semantics-style-resolution-processing-sss
>
> though I see I need to update that step to handle references to
> out-of-line animations;
>
> note also that in the current specified style set algorithm, if multiple
> specifications contribute to a given style, then the last one applied wins,
> not the first one;
>
>
> That's what I'd expect also.
>
>
>
>>
>> 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.
>>
>
> in general, we have found it easier and more consistent to allow (at least
> discrete) animation of all styles, even if one might not use them very
> often (or ever); so i would not want to create an exclusion set here
>
>
> We already have an implied exclusion set because some style attributes
> that affect regions are permitted on content elements and create anonymous
> inline regions but others do not. My lists are coincident with those two
> sets. To remove the current implied exclusion sets we would need to permit
> all style attributes on regions and all content elements and those that
> only have an effect on regions would create an anonymous inline
> [region|set].
>
> I quite like the sets as they are – they seem to make sense.
>
>
>
>>
>> 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 …
>>
>
> the note under [2] indicates
>
> "A content element
> <https://dvcs.w3.org/hg/ttml/raw-file/tip/ttml2/spec/ttml2.html#terms-content-element> can
> only be associated with a single region
> <https://dvcs.w3.org/hg/ttml/raw-file/tip/ttml2/spec/ttml2.html#terms-region>.
> Consequently, if a content element
> <https://dvcs.w3.org/hg/ttml/raw-file/tip/ttml2/spec/ttml2.html#terms-content-element> specifies
> a region
> <https://dvcs.w3.org/hg/ttml/raw-file/tip/ttml2/spec/ttml2.html#layout-attribute-region> attribute,
> then any *implied inline region specification* or *explicit inline region
> specification* is ignored. If the content element
> <https://dvcs.w3.org/hg/ttml/raw-file/tip/ttml2/spec/ttml2.html#terms-content-element> does
> not specify a region
> <https://dvcs.w3.org/hg/ttml/raw-file/tip/ttml2/spec/ttml2.html#layout-attribute-region> attribute,
> but it includes both an *implied inline region specification* and an *explicit
> inline region specification*, then the former is ignored in favor of the
> latter."
>
> [2]
> https://dvcs.w3.org/hg/ttml/raw-file/tip/ttml2/spec/ttml2.html#semantics-inline-regions
>
> there is an editorial note under [3] to add normative language that
> effects the above informatively described semantics
>
> [3]
> https://dvcs.w3.org/hg/ttml/raw-file/tip/ttml2/spec/ttml2.html#procedure-associate-region
>
>
> Interesting. Then the other approach we could take is to start with the
> explicit region specification and modify it with the attributes of the
> implied inline region to synthesise a new anonymous region. In other words,
> specify how the set of regions is merged to create a single region that the
> content goes into.
>
>
>
>>
>> Any thoughts on this appreciated, even if they're "Aargh don't change it
>> now"!
>>
>
> perhaps we could introduce the ability for an inline animation to target
> its region; i'll give this some thought
>
>
> Sounds neat.
>
>
>
>>
>> Nigel
>>
>>
>>
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