Re: Comment added to inline box issue

On Wed, Apr 19, 2017 at 3:07 PM, Dae Kim <dakim@netflix.com> wrote:

> David and Eleka both feel any solution for this should end up in CSS
> Inline Level 3 <https://drafts.csswg.org/css-inline/>. Based on our own
> TTML2/IMSC2 timelines, the best we can realistically hope for in terms of a
> CSS solution is a WD or ED while we're preparing for TTML2 Rec.
>
> Given how new this stretch concept is (and assuming other members of CSS
> are on board), do we feel comfortable baking TTML2/IMSC2 with a CSS draft
> concept?
>

The suggested approach, of adding a keyword to the height property, is
effectively the same as we have proposed [1], which is to add keywords to a
new style property tts:bpdContent or an existing style property tts:bpd.

In that proposal, we had suggested a new property tts:bpdContent since
tts:bpd was used to trigger inline-block semantics. However, when we
reviewed this in London, we decided to drop this special trigger semantic
(and instead use explicit semantics via a new "inlineBlock" value on
tts:display). This will allow us to use tts:bpd to solve this problem
(about the 'height' of inline non-replaced elements) instead of introducing
a new property tts:bpdContent.

So, in the end, we have tts:bpd="bpdLine" or tts:bpd="bpdLineLeaded" as the
way to designate that the content height of the inlines should *stretch* or
fill the line area height up to and either excluding or including leading.

In other words, where a future CSS Inline Level 3 might have "height:
stretch" we would have "tts:bpd='bpdLineLeaded'", i.e., the height of the
line area's content area plus the height of leading. Of course, this would
depend on the CSS WG defining "stretch" or some other keyword with
equivalent semantics.

[1] https://github.com/w3c/ttml2/issues/150#issuecomment-192490492

I suggest we go ahead with defining whichever keywords we want to use with
tts:bpd, and not create a highly risky dependency on a future CSS Inline
Level 3 document an equivalent keyword. Of course, once we define our
keyword, we can officially ask the CSS WG to define an equivalent on height
in a future document that would apply to non-replaced inline boxes.



>
> -Dae
>
> *Dae Kim | Senior Video Engineer | Encoding Technology*
> *9420 94f4 a834 b038 2920 34b3 38ad b632 3738 942c 942f*
>
> On Wed, Apr 19, 2017 at 9:49 AM, Nigel Megitt <nigel.megitt@bbc.co.uk>
> wrote:
>
>> For those not following the issue on github there has been a response
>> about the request to be able to set the background height of inline areas –
>> see https://github.com/w3c/csswg-drafts/issues/814#issuecomment-295122693
>>
>>
>> Nigel
>>
>>
>>
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