ISSUE-176: Adding support for extent and origin attributes on block elements

extent and origin on blocks

Adding support for extent and origin attributes on block elements

State:
CLOSED
Product:
TTML2
Raised by:
Glenn Adams
Opened on:
2012-08-23
Description:
It has become common practice to use the extent and origin attributes directly on block elements (specifically <p>), as this greatly simplifies authoring and conversion process. This is essentially akin to creating 'anonymous' regions for each block, or relative positioning in CSS.

The TTML 1.0 spec allows this syntactically but did not specify any meaning. We should resolve this by supplying reference semantics for the practice.
Related Actions Items:
Related emails:
  1. {minutes} TTWG Meeting 12/6/2014 (from nigel.megitt@bbc.co.uk on 2014-06-12)
  2. {minutes} TTWG Meeting 17/4/2014 (from nigel.megitt@bbc.co.uk on 2014-04-17)
  3. {agenda} TTWG Meeting 17/4/2014 (from nigel.megitt@bbc.co.uk on 2014-04-17)
  4. {minutes} TTWG Meeting 27/3/2014 (from nigel.megitt@bbc.co.uk on 2014-03-27)
  5. {minutes} TTWG Meeting 6/2/2014 (from nigel.megitt@bbc.co.uk on 2014-02-06)
  6. TTML Minutes for 15/11/13 (from nigel.megitt@bbc.co.uk on 2013-11-21)
  7. {minutes} Halloween TTML Meeting and Thank You Sean (from plh@w3.org on 2013-10-31)
  8. {minutes} TTML Meeting of 24/10/13 (from glenn@skynav.com on 2013-10-24)
  9. RE: TTML Agenda for 24/10/13 (from mdolan@newtbt.com on 2013-10-23)
  10. TTML Agenda for 24/10/13 (from nigel.megitt@bbc.co.uk on 2013-10-23)
  11. TTML Agenda for 03/10/13 (from Sean.Hayes@microsoft.com on 2013-10-03)
  12. Re: TTML Minutes for 25/09/13 (from tmichel@w3.org on 2013-09-27)
  13. RE: TTML Minutes for 25/09/13 (from silviapfeiffer1@gmail.com on 2013-09-27)
  14. RE: TTML Minutes for 25/09/13 (from nigel.megitt@bbc.co.uk on 2013-09-26)
  15. TTML Agenda for 25/09/13 (from Sean.Hayes@microsoft.com on 2013-09-25)
  16. TTML Agenda for 19/09/13 (from Sean.Hayes@microsoft.com on 2013-09-19)
  17. No Meeting today 12-09-13 (from Sean.Hayes@microsoft.com on 2013-09-12)
  18. Minutes for 05/09/13 (from nigel.megitt@bbc.co.uk on 2013-09-05)
  19. Agenda for 05/09/13 (from glenn@skynav.com on 2013-09-04)
  20. RE: TTML Agenda for 29/08/13 (from mdolan@newtbt.com on 2013-08-28)
  21. TTML Agenda for 29/08/13 (from glenn@skynav.com on 2013-08-28)
  22. RE: TTML Agenda for 15/05/13 (from mdolan@newtbt.com on 2013-05-15)
  23. RE: ISSUE-176 (extent and origin on blocks): Adding support for extent and origin attributes on block elements [DFXP v.next] (from mdolan@newtbt.com on 2012-09-07)
  24. Re: TTML Agenda for 6/9/12 (from geoff_freed@wgbh.org on 2012-09-06)
  25. TTML Agenda for 6/9/12 (from Sean.Hayes@microsoft.com on 2012-09-06)
  26. RE: [minutes] 20120823 TTML (from momartin@microsoft.com on 2012-08-23)
  27. [minutes] 20120823 TTML (from plh@w3.org on 2012-08-23)
  28. ISSUE-176 (extent and origin on blocks): Adding support for extent and origin attributes on block elements [DFXP v.next] (from sysbot+tracker@w3.org on 2012-08-23)

Related notes:

Handle this by defining Inline Regions for block class elements (div, p), e.g.

<p>
<region tts:origin="..." tts:extent="..."/>
Some Text in an anonymous Inline Region
</p>

This is preferable to defining origin and extent on p itself, which could be easily misinterpreted as meaning that these properties apply to the allocation rectangle (margin box) and content rectangle (content box), respectively.

See https://dvcs.w3.org/hg/ttml/diff/bb877bfc347c/ttml2/spec/ttml2.xml and https://dvcs.w3.org/hg/ttml/rev/c78dca2ae3ca. Still TBD is elaborating semantics of Inline Regions in Section 9.3.

Glenn Adams, 28 Aug 2013, 18:17:08

[glenn]: nigel asks about whether region needs full specification or can be inherited

5 Sep 2013, 14:56:18

Raised by Sean Hayes

Philippe Le Hégaret, 24 Oct 2013, 15:24:58

Sean: this is practice in the industry

Nigel: P1

Philippe Le Hégaret, 24 Oct 2013, 15:25:57

I added this note in my action item ACTION-205, but I should probably be in this thread as well.

One difference I notice in the CPC output from the examples outlined in http://www.w3.org/wiki/TTML/changeProposal002 is that each p with tts:origin and tts:extent from CPC has an explicitly defined target region attribute, which makes it easier to understand the target region for positioning.


<tt xml:lang="en" xmlns="http://www.w3.org/ns/ttml" xmlns:tts="http://www.w3.org/ns/ttml#styling" xmlns:ttm="http://www.w3.org/ns/ttml#metadata" xmlns:ttp="http://www.w3.org/ns/ttml#parameter" ttp:timeBase="media" ttp:frameRate="24" ttp:frameRateMultiplier="1000 1001">

<head>

<styling>

<style xml:id="basic" tts:color="white" tts:backgroundColor="black" tts:fontFamily="monospace" tts:fontSize="80%" tts:fontWeight="normal" tts:fontStyle="normal"/>

</styling>

<layout>

<region xml:id="pop1" tts:backgroundColor="transparent" tts:showBackground="whenActive"/>

</layout>

</head>

<body>

<div>

<p begin="nn:nn:nn:nn" end="nn:nn:nn:nn"
region="pop1"
style="basic"
tts:origin="10% 84.67%" tts:extent="50% 5.33%">
The quick brown fox
</p>

</div>

</body>

</tt>

I'm not sure that this makes a difference with Glenn's concerns regarding the potential for confusion over the meaning of the properties and how they should be applied.

Michael Jordan, 1 Nov 2013, 20:15:41

[glenn]: Note that Action-215 will adopt support for tts:{extent,origin} directly on <p> as a shorthand for specifying an inline region.

15 Nov 2013, 02:05:11

addressed in https://dvcs.w3.org/hg/ttml/rev/c9fd49837446

Glenn Adams, 27 Mar 2014, 07:16:12

Changelog:

Created issue 'Adding support for extent and origin attributes on block elements' nickname extent and origin on blocks owned by Sean Hayes on product DFXP v.next, description 'It has become common practice to use the extent and origin attributes directly on block elements (specifically <p>), as this greatly simplifies authoring and conversion process. This is essentially akin to creating 'anonymous' regions for each block, or relative positioning in CSS.

The TTML 1.0 spec allows this syntactically but did not specify any meaning. We should resolve this by supplying reference semantics for the practice.' non-public

Sean Hayes, 23 Aug 2012, 10:08:21

Status changed to 'open'

Monica Martin, 30 Aug 2012, 16:26:11

Status changed to 'pending review'

Glenn Adams, 28 Aug 2013, 18:17:21

Status changed to 'open'

3 Oct 2013, 15:27:26

Owner changed to 'Glenn Adams'

Philippe Le Hégaret, 24 Oct 2013, 15:25:57

Status changed to 'pending review'

Glenn Adams, 27 Mar 2014, 07:16:12

Status changed to 'closed'

17 Apr 2014, 14:40:05


David Singer <singer@apple.com>, Nigel Megitt <nigel.megitt@bbc.co.uk>, Chairs, Thierry Michel <tmichel@w3.org>, Philippe Le Hégaret <plh@w3.org>, Staff Contacts
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