RE: 'knife and fork' model

Glenn,
 
comments below in green

-----Original Message-----
From: Glenn A. Adams [mailto:glenn@xfsi.com]
Sent: 12 August 2003 16:48
To: Johnb@screen.subtitling.com
Cc: public-tt@w3.org
Subject: RE: 'knife and fork' model


I guess what you are describing is essentially:
 

1.	authoring time line layout (hard layout) 

2.	presentation time line layout (soft layout)

We have already included the style property wrap-option, defined at [1] to
support authoring time determination of which of these models apply. 
[JB> ] CSS wrap-option property does not have a value that produces balanced
lines. Justification properties do not appear to help either.
 
In order to express authoring time line separators, we have included force
line break as a presentation flow vocabulary item and break-after and
break-before as style properties that induce the same effect.
[JB> ] Might I suggest also a requirement for prefix-before in order to
support the inclusion of symbols such as # (for music) and - or >> for
speaker change? Or can this be handled in another way? - can't be in content
if supporting soft layout!
 
What we haven't yet defined in the requirements document is an ability for
the author to express timing or style semantics to be applied to line areas
that are produced by the second of the above modes (soft layout). This is
why I suggested the idea of a pseudo selector that allows expressing
authorial intent about objects that are produced by an implied presentation
process, i.e., line and glyph areas.
[JB> ]  The pseudo selector may allow the imposition of style on soft layout
- though I have questions - see other post. However, I don't see how it
works for timing. Given soft timing of text into a given sized region -
there is nothing that hints to the UA how to control the flow of text into
that region. The display property gives boolean control (visible | hidden)
but not a pop on , off, on mode. There is no property to control the mark
space ratio between visible and hidden during the soft timed period. If you
are intending to use the region as a snaked or line by line region you would
set the overflow properties to scroll - but there is insufficient subtlety
in the related properties to achieve the desired effect.



[JB> ] I will try and enumerate all the possible combinations that might be
wanted, as a sequence of diagrams of how the region would change over time.
I know you asked for this originally - but I was hoping I might avoid it :-)

regards 
John Birch 

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reflect the views and opinions of Screen Subtitling Systems Limited.