[imsc] Improve itts:forcedDisplay description

palemieux has just created a new issue for https://github.com/w3c/imsc:

== Improve itts:forcedDisplay description ==
>From an implementer:

> i was having trouble parsing the indicated text from the specification:

> "If and only if the value of displayForcedOnlyMode is "true", a
content element with a itts:forcedDisplay computed value of "false"
shall not produce any visible rendering, but still affect layout,
regardless of the computed value of tts:visibility."

> the following being the dilemma - in the above case, layout is affected in the sense that the invisible content element counts towards presentation (tts:visibility?) OR it is affected in the sense that it is not considered for presentation (tts:display?) 

Proposed amended text:

_If and only if the value of displayForcedOnlyMode is "true", a
content element with a itts:forcedDisplay computed value of "false"
shall not produce any visible rendering,
regardless of the computed value of tts:visibility._

_The itts:forcedDisplay attribute has no affect on content layout or
composition, but merely determines whether composed content is visible
or not._

This follows the prose of `tts:visibility` in TTML1.

Please view or discuss this issue at https://github.com/w3c/imsc/issues/284 using your GitHub account

Received on Tuesday, 21 November 2017 19:29:37 UTC