ISSUE-72: Smooth scrolling by means of reference area offset

smooth scrolling

Smooth scrolling by means of reference area offset

State:
CLOSED
Product:
TTML2
Raised by:
Pierre-Anthony Lemieux
Opened on:
2009-04-24
Description:
The only means of easily defining a smooth scroll in TT is dependant on invoking the dynamicFlow engine. Dynamic flow is a complex feature and is not needed for several common scenarios (ticker tape, roll up credits, roll up captions).

It is not clear what layout area the block fill unit works on (whether it is the entire containing block in the region, or the set of blocks enclosing the paragraph level), if the former then it might be possible to invoke:
dynamicFlow: in(block, smooth) out(block,smooth) and not incur a layout penalty; however even in this case it is not possible to specify the direction the scroll function operates in.

proposal: add a property in timed text which allows independant authorial control over the inline-scroll-amount, and block-scroll-amount for the block-container-region generated for a region.

scroll:
Values: <digit>+ (unit)? ((<length> | auto) (<length> | auto) (<duration> | auto) (<duration> | auto))?
Initial: 0 auto auto auto auto
Applies to: region
Inherited: no
Percentages: relative to width and height of region

If the overflow property of the region of is set to scroll, then the scroll property of the region applies. The reference-area of the block-container is considered to be large enough to accommodate the maximimum specified scroll amount in each direction, and the XSL inline-scroll-amount, and block-scroll-amount deemed to apply. The scroll is defined over time the region is active due to content being selected into it.

The durations are either explicit times or auto. The value auto in this context meaning the temporal difference between the synchronic slice T(k1) which occurs at each time the region becomes active (content is selected into it), and the closest subsequent slice T(k2) when no content is selected into the region.

The lengths specified in the scroll property define the maximum values Li for inline-scroll-amount, and Lb block-scroll-amount respectively over each active duration.

The value auto for length is defined as the difference V - Dm, where V = the corresponding dimension of the viewport, and Dm = the maximum dimension in the corresponding progression dimension of the initial containing block over all synchronic slices between T(k1) and T(k2).

The number of steps of i over each duration is defined by the initial <digit>+. If no units are specified, a set of i intermediate synchronic slices at times T(ki) are defined evenly spaced between T(k1) and T(k2) (rounded to the closest available clock times).
If a unit is specified it defines an interval I, and the i intermediate synchronic slices are defined for all n where T(k) < T(k1 + (n * I)) < T(k2), (again rounded to the closest available clock times).

The offset values at intermediate slice i are defined by : (L / duration) * (T(ki)-T(k1)).
Related Actions Items:
Related emails:
  1. {agenda} TTWG Meeting 17/7/2014 (from nigel.megitt@bbc.co.uk on 2014-07-16)
  2. out-of-line-animation (from nigel.megitt@bbc.co.uk on 2014-07-11)
  3. TTWG Agenda for 12/12/13 (from nigel.megitt@bbc.co.uk on 2013-12-11)
  4. Re: TTWG Agenda for 5/12/13 (from nigel.megitt@bbc.co.uk on 2013-12-11)
  5. Re: TTWG Agenda for 5/12/13 (from glenn@skynav.com on 2013-12-11)
  6. RE: TTWG Agenda for 5/12/13 (from mdolan@newtbt.com on 2013-12-10)
  7. TTWG Minutes for 5/12/13 (from nigel.megitt@bbc.co.uk on 2013-12-05)
  8. TTWG Agenda for 5/12/13 (from nigel.megitt@bbc.co.uk on 2013-12-04)
  9. Re: TTML Agenda for 21/11/13 (from cyril.concolato@telecom-paristech.fr on 2013-11-21)
  10. Re: TTML Agenda for 21/11/13 (from glenn@skynav.com on 2013-11-21)
  11. Re: TTML Agenda for 21/11/13 (from tmichel@w3.org on 2013-11-21)
  12. TTML Agenda for 21/11/13 (from nigel.megitt@bbc.co.uk on 2013-11-20)
  13. {minutes} Halloween TTML Meeting and Thank You Sean (from plh@w3.org on 2013-10-31)
  14. RE: TTML Agenda for 31/10/13 (from Sean.Hayes@microsoft.com on 2013-10-31)
  15. TTML Agenda for 31/10/13 (from nigel.megitt@bbc.co.uk on 2013-10-30)
  16. {minutes} TTML Meeting of 24/10/13 (from glenn@skynav.com on 2013-10-24)
  17. RE: TTML Agenda for 24/10/13 (from mdolan@newtbt.com on 2013-10-23)
  18. TTML Agenda for 24/10/13 (from nigel.megitt@bbc.co.uk on 2013-10-23)
  19. Re: TTML Minutes for 25/09/13 (from tmichel@w3.org on 2013-09-27)
  20. RE: TTML Minutes for 25/09/13 (from silviapfeiffer1@gmail.com on 2013-09-27)
  21. RE: TTML Minutes for 25/09/13 (from nigel.megitt@bbc.co.uk on 2013-09-26)
  22. TTML Agenda for 25/09/13 (from Sean.Hayes@microsoft.com on 2013-09-25)
  23. TTML Agenda for 19/09/13 (from Sean.Hayes@microsoft.com on 2013-09-19)
  24. No Meeting today 12-09-13 (from Sean.Hayes@microsoft.com on 2013-09-12)
  25. Minutes for 05/09/13 (from nigel.megitt@bbc.co.uk on 2013-09-05)
  26. Agenda for 05/09/13 (from glenn@skynav.com on 2013-09-04)
  27. RE: TTML Agenda for 29/08/13 (from mdolan@newtbt.com on 2013-08-28)
  28. TTML Agenda for 29/08/13 (from glenn@skynav.com on 2013-08-28)
  29. RE: [minutes] 20120823 TTML (from momartin@microsoft.com on 2012-08-23)
  30. [minutes] 20120823 TTML (from plh@w3.org on 2012-08-23)
  31. TTML Agenda for 23/8/12 (from Sean.Hayes@microsoft.com on 2012-08-23)
  32. Minutes TTWG Aug 16, 2012 (from momartin@microsoft.com on 2012-08-17)
  33. RE: TTML Agenda for 15/8/12 (from momartin@microsoft.com on 2012-08-16)
  34. Fwd: TTML Agenda for 15/8/12 (from geoff_freed@wgbh.org on 2012-08-16)
  35. Re: TTML Agenda for 15/8/12 (from geoff_freed@wgbh.org on 2012-08-16)
  36. TTML Agenda for 15/8/12 (from Sean.Hayes@microsoft.com on 2012-08-16)
  37. RE: {minutes} TTML Agenda for 12/4/12 (from mdolan@newtbt.com on 2012-04-17)
  38. {minutes} TTML Agenda for 12/4/12 (from glenn@skynav.com on 2012-04-12)
  39. RE: TTML Agenda for 12/4/12 (from geoff_freed@wgbh.org on 2012-04-11)
  40. {status} [was Re: TTML Agenda for 8/3/12] (from glenn@skynav.com on 2012-03-08)
  41. [TTWG] Draft Minutes (was: Re: TTML Agenda for 1/3/12) (from glenn@skynav.com on 2012-03-01)
  42. Re: TTML Agenda for 23/2/12 (from geoff_freed@wgbh.org on 2012-02-22)
  43. Re: TTML Weekly meetings (from glenn@skynav.com on 2012-02-16)
  44. Agenda for meeting 22-05-09 (from Sean.Hayes@microsoft.com on 2009-05-22)
  45. ISSUE-72 (smooth scrolling): Smooth scrolling by means of reference area offset [DFXP 1.0] (from sysbot+tracker@w3.org on 2009-04-24)

Related notes:

To deal with in next version.

Sean Hayes, 22 May 2009, 14:05:46

Add support for continuous animation using animate element. https://dvcs.w3.org/hg/ttml/rev/1d13586de640

Glenn Adams, 27 Aug 2013, 01:14:17

[glenn]: submitter needs to review and comment

29 Aug 2013, 15:42:17

While a smooth animation facility may be able to support this; it needs an effective property to work on. This hasn't been added, so the issue is reopened.
In addition it is not clear whether the scrolling should be handled by explicit timing, or whether an implicit property on regions should be utilized.

Sean Hayes, 3 Oct 2013, 10:17:33

Raised by Sean Hayes

Philippe Le Hégaret, 24 Oct 2013, 15:10:11

Sean: P2, maybe P1

PAL to follow-up with Mike

Philippe Le Hégaret, 24 Oct 2013, 15:11:37

Mike: this was adequately addressed in TTML 1 (2nd Ed) so P4.

Nigel Megitt, 31 Oct 2013, 14:30:37

Closing for now as there's no champion for this issue.

Nigel Megitt, 31 Oct 2013, 14:31:04

[glenn]: consider this as WONTFIX or LATER

31 Oct 2013, 14:31:40

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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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