Checkpoint 4.6: Proposed clarifications

Hello,

In the 11 April 2001 draft [1] of UAAG 1.0, checkpoint 4.6 reads:

  4.6 For graphical viewports, allow the user to position text 
      transcripts, collated text transcripts, and captions in 
      the viewport. Allow the user to choose from among at least 
      the range of positions available to the author (e.g., 
      the range of positions allowed by the markup or style 
      language).

Based on discussion and resolutions at the 19 April 
2001 teleconference [2], I am trying to clarify the checkpoint. 
The fully revised checkpoint is at the end of this email.

Things to take into account:

0) This checkpoint is about control of captions position with
   respect to one or more synchronized visual tracks (and not
   just any other piece of content). This checkpoint is 
   for graphical viewports only.

1) This checkpoint should only be about synchronized text tracks,
   not [collated] text transcripts. I think the whole point of this
   checkpoint is to ensure that synchronized information is both
   legible and nearby. I think that in general, authors will specify
   captions to accompany a visual track (in the same viewport), but
   not transcripts.

   Proposed: Drop text transcripts and collated text transcripts
   from this checkpoint. Note that checkpoint 2.5 also refers to
   [collated] text transcripts and should continue to do so: this
   ensures that they are available at the same time as a visual
   track.

2) Respect the author's positions and styles (e.g.,
   colors, etc.) as expressed in the content. However, allow
   the user to override the author's specified position.

4) The user agent is not required to lay out other content
   (i.e., reflow) after the user has changed the position of
   captions.

5) If the user agent satisfies this checkpoint by using a markup
   language or style sheet language for control, then the user agent
   must allow the user to choose from among at least the range of
   positions enabled by the format.

6) If the user agent satisfies this checkpoint otherwise (e.g.,
   by making available captions in a separate viewport), then
   the user agent must:

   a) Allow the user to position the captions to
      overlap the visual track. The captions background
      should be transparent to allow the visual track
      to show through. 

   b) Allow the user to position the captions to
      not overlap the visual track.

7) The checkpoint should allow for configuration or control.

Given all of this:

<NEW 4.6>
   For graphical viewports, allow the user to position captions
   with respect to synchronized visual tracks as follows: If the
   user agent satisfies this checkpoint by using a markup
   language or style sheet language to provide configuration or
   control, then the user agent must allow the user to choose
   from among at least the range of positions enabled by the
   format. Otherwise, the user agent must allow both
   non-overlapping and overlapping positions (e.g., by rendering
   captions in a separate viewport that may be positioned on top
   of the visual track). The user agent must allow the user to
   override the author's specified position. The user agent is
   not required to change the layout of other content (i.e.,
   reflow) after the user has changed the position of captions.

     Note: When captions overlap the synchronized visual track,
     the user should be able to view the visual track behind 
     the captions. Refer to checkpoint 4.3 for requirements
     related to the control of background colors.
</NEW 4.6>

 - Ian


[1] http://www.w3.org/WAI/UA/WD-UAAG10-20010411/
[2] http://lists.w3.org/Archives/Public/w3c-wai-ua/2001AprJun/0046

-- 
Ian Jacobs (ij@w3.org)   http://www.w3.org/People/Jacobs
Tel:                     +1 831 457-2842
Cell:                    +1 917 450-8783

Received on Tuesday, 22 May 2001 13:11:06 UTC