ISSUE-368: The [Construct Intermediate Document] process erroneously prunes empty <br> elements

ISD construction prunes <br/> erroneously

The [Construct Intermediate Document] process erroneously prunes empty <br> elements

State:
OPEN
Product:
TTML 1.0
Raised by:
Nigel Megitt
Opened on:
2015-01-29
Description:
The [construct intermediate document] process says:

"2. evaluating this sub-tree in a postorder traversal, prune elements if
they are not a Content element, if they are temporally inactive, if they
are empty, or if they aren't associated with region R according to the
[associate region] procedure;"

This means that any empty <br> element e.g. "<br/>" is pruned, resulting in it having no effect. This isn't the correct behaviour because empty <br> elements should create line breaks and therefore have an effect.

This applies to TTML1, TTML1SE and TTML2.
Related Actions Items:
No related actions
Related emails:
  1. {agenda} TTWG Meeting 2015-10-22 (from nigel.megitt@bbc.co.uk on 2015-10-21)
  2. Re: TTML2 anonymous inline region creation (from nigel.megitt@bbc.co.uk on 2015-10-21)
  3. Re: TTML2 anonymous inline region creation (from glenn@skynav.com on 2015-10-21)
  4. Re: TTML2 anonymous inline region creation (from glenn@skynav.com on 2015-10-21)
  5. RE: TTML2 anonymous inline region creation (from John.Birch@screensystems.tv on 2015-10-21)
  6. Re: TTML2 anonymous inline region creation (from glenn@skynav.com on 2015-10-21)
  7. RE: TTML2 anonymous inline region creation (from John.Birch@screensystems.tv on 2015-10-21)
  8. Re: TTML2 anonymous inline region creation (from glenn@skynav.com on 2015-10-20)
  9. Re: TTML2 anonymous inline region creation (from nigel.megitt@bbc.co.uk on 2015-10-20)
  10. Re: TTML2 anonymous inline region creation (from glenn@skynav.com on 2015-10-20)
  11. Re: TTML2 anonymous inline region creation (from glenn@skynav.com on 2015-10-20)
  12. TTML2 anonymous inline region creation (from nigel.megitt@bbc.co.uk on 2015-10-20)
  13. April F2F Meeting minutes (from nigel.megitt@bbc.co.uk on 2015-04-22)
  14. {agenda} TTWG Meeting 2015-04-02 (from nigel.megitt@bbc.co.uk on 2015-04-01)
  15. {minutes} TTWG Meeting 2015-01-29 (from nigel.megitt@bbc.co.uk on 2015-01-29)
  16. ISSUE-368 (ISD construction prunes <br/> erroneously): The [Construct Intermediate Document] process erroneously prunes empty <br> elements [TTML 1.0] (from sysbot+tracker@w3.org on 2015-01-29)

Related notes:

I've just spotted that there's a Note in §8.1.4 div that hints at the same logic. It says "If some block area generated by a div element does not contain any child areas, then it is not expected to be presented." however if the only child areas are generated by <br> elements then I would expect the equivalent of a strut in the block progression dimension, corresponding to the sum of the heights of the lines implied by the <br>s to be taken into account in the presentation, and for the div's block area to be presented.

It may also be helpful to indicate in §8.1.7 br that the presence of an active <br> is considered to cause the parent elements to be displayed, even if there are no content areas generated.

Nigel Megitt, 26 Mar 2015, 16:52:11

[nigel]: [Meeting 2015-04-10] Any empty content element that generates an area e.g. by setting ipd or bpd must not be pruned either.

10 Apr 2015, 15:46:23

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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>, Atsushi Shimono <atsushi@w3.org>, Staff Contacts
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