ISSUE-180: regions relative to the root container

regions relative to the root container

State:
CLOSED
Product:
TTML 1.0
Raised by:
Mike Dolan
Opened on:
2012-09-07
Description:
As currently specified, the values of origin and extent are both unconstrained – they can take any positive or negative number without constraint relative to the root container. But I don’t know what it means to have a region wholly or partially outside the root container, or what to do with negative extent values. I had always assumed that regions had to be wholly contained within the root container and both origin and extent had to be non-negative. But the spec is not clear to me.

8.2.7 tts:extent says: "...the initial value of the style property [auto] must be considered to be the same as the root container extent." Does this mean that it literally takes the value of the width and height of the root container, or does it mean that it is set to whatever area remains to the right and bottom of the origin contained entirely within the root container?

It additionally says: "If a specified value of this attribute is not supported, then a presentation processor must interpret the attribute as if the value auto were specified." If a region can exceed the area of the root container, then what value(s) are not supported exactly? It would currently be implementation dependent, and thus could be clipped by a presentation processor to be the root container or not at all or something inbetween.

Whether regions are clipped to be within the root container or not changes the flow behavior considerably (and thus the visible presentation), so leaving it to be implementation dependent seems non-interoperable.
Related Actions Items:
Related emails:
  1. Minutes - 2013-07-18 (from glenn@skynav.com on 2013-07-18)
  2. ISSUE-262: tts:extent semantics if value not supported [TTML.next] (from sysbot+tracker@w3.org on 2013-07-11)
  3. Minutes - 2013-06-20 (from glenn@skynav.com on 2013-07-11)
  4. Minutes - 2013-07-11 (from glenn@skynav.com on 2013-07-11)
  5. [minutes] Timed Text call June 20, 2013 (from plh@w3.org on 2013-06-27)
  6. Re: TTML Agenda for 20/06/13 -- ADVANCE NOTICE -- (from tai@irt.de on 2013-06-19)
  7. TTML Agenda for 20/06/13 -- update -- (from Sean.Hayes@microsoft.com on 2013-06-19)
  8. Re: TTML Agenda for 20/06/13 -- ADVANCE NOTICE -- (from glenn@skynav.com on 2013-06-19)
  9. Re: TTML Agenda for 20/06/13 -- ADVANCE NOTICE -- (from tai@irt.de on 2013-06-19)
  10. Re: TTML Agenda for 20/06/13 -- ADVANCE NOTICE -- (from glenn@skynav.com on 2013-06-18)
  11. Re: TTML Agenda for 20/06/13 -- ADVANCE NOTICE -- (from glenn@skynav.com on 2013-06-18)
  12. TTML Agenda for 20/06/13 -- ADVANCE NOTICE -- (from Sean.Hayes@microsoft.com on 2013-06-17)
  13. TTWG Agenda March 7, 2013 (from momartin@microsoft.com on 2013-03-07)
  14. Re: TTML Agenda for 28/2/13 (from glenn@skynav.com on 2013-02-28)
  15. RE: TTML Agenda for 28/2/13 (from mdolan@newtbt.com on 2013-02-28)
  16. TTML Agenda for 28/2/13 (from momartin@microsoft.com on 2013-02-28)
  17. TTML Agenda for 21/02/13 (from Sean.Hayes@microsoft.com on 2013-02-21)
  18. TTWG Meeting Minutes Feb 7, 2013 (from momartin@microsoft.com on 2013-02-14)
  19. TTML Agenda for 14/02/13 (from Sean.Hayes@microsoft.com on 2013-02-14)
  20. TTWG Meeting Minutes Feb 7, 2013 (from momartin@microsoft.com on 2013-02-07)
  21. TTML Agenda for 07/02/13 (from Sean.Hayes@microsoft.com on 2013-02-07)
  22. RE: TTML Agenda for 15/11/12 (from mdolan@newtbt.com on 2012-11-15)
  23. TTML Agenda for 15/11/12 (from Sean.Hayes@microsoft.com on 2012-11-15)
  24. RE: ISSUE-180: regions relative to the root container [DFXP 1.0] (from Sean.Hayes@microsoft.com on 2012-11-12)
  25. Re: ISSUE-180: regions relative to the root container [DFXP 1.0] (from glenn@skynav.com on 2012-11-12)
  26. TTML Agenda for 1/11/12 (from Sean.Hayes@microsoft.com on 2012-11-01)
  27. RE: ISSUE-180: regions relative to the root container [DFXP 1.0] (from momartin@microsoft.com on 2012-10-18)
  28. RE: TTML Agenda for 20/9/12 (from Sean.Hayes@microsoft.com on 2012-09-20)
  29. ISSUE-180: regions relative to the root container [DFXP 1.0] (from sysbot+tracker@w3.org on 2012-09-07)

Related notes:

TTWG Oct 25: http://www.w3.org/2012/10/25-tt-minutes.html. Discussion - TTML 1.0 needs clarification. Defer as TTML 1.1 issue.

Monica Martin, 30 Oct 2012, 19:36:36

Disregard the previous note today Oct 30 as it is related to Issue-173. Sorry. Monica

Monica Martin, 30 Oct 2012, 19:37:17

Add new text for R0020 at http://dvcs.w3.org/hg/ttml/rev/f14109829d28. Did not revise R0040 yet.

Glenn Adams, 12 Nov 2012, 17:34:55

TTWG Nov 15: http://www.w3.org/2012/11/15-tt-minutes.html

Glenn clarified what he had done on definition of root container and related issues - Issues 180 and 194.

R0020, R0021, and R0022.

Monica Martin, 16 Nov 2012, 02:23:48

pending Review for SDP-US only.

Monica Martin, 16 Nov 2012, 02:25:03

TTWG Nov 29: http://lists.w3.org/Archives/Public/public-tt/2012Nov/0029.html.

Added definitions in SDP-US and constraints.

Leave open for TTML 1.0.

Monica Martin, 2 Dec 2012, 23:23:15

add text in 8.2.7:

"where, if either width or height is negative or zero, then extent must be considered zero in both inline and block progression dimensions"

Glenn Adams, 2 May 2013, 05:38:29

[plh]: https://dvcs.w3.org/hg/ttml/raw-file/tip/ttml10/spec/ttaf1-dfxp.html#style-attribute-extent

20 Jun 2013, 14:40:44

tts:extent can no longer take negative values (actually width/height was always constrained to non-negative by XSL-FO); we've now made this explicit in spec: https://dvcs.w3.org/hg/ttml/rev/60bbc0feed94

tts:origin can take negative values, which are legitimate, meaning region may not be visible or only partly visible; the applicable language can be found in TTML10 REC in the definition of root container region (section 2.2):

Root Container Region
A logical region that establishes a coordinate system into which content regions are placed and optionally clipped.

it is up to the document processing context to determine whether the RC region is clipped or not;

a use case for negative origin is to fly/slide a region into the RC region from without by using <set/> animation on the region's origin;

i don't believe there is any issue here remaining for TTML1.0SE, so am moving to Pending Review; if something new is suggested for TTML.next, then I'd suggest a new issue be raised, which can refer to this issue for historical context

Glenn Adams, 27 Jun 2013, 16:10:02

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