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ISSUE-180: regions relative to the root container [DFXP 1.0]

From: Timed Text Working Group Issue Tracker <sysbot+tracker@w3.org>
Date: Fri, 07 Sep 2012 17:46:25 +0000
Message-Id: <E1TA2dN-0001ol-II@tibor.w3.org>
To: public-tt@w3.org
ISSUE-180: regions relative to the root container [DFXP 1.0]


Raised by: Mike Dolan
On product: DFXP 1.0

As currently specified, the values of origin and extent are both unconstrained – they can take any positive or negative number without constraint relative to the root container. But I don’t know what it means to have a region wholly or partially outside the root container, or what to do with negative extent values.  I had always assumed that regions had to be wholly contained within the root container and both origin and extent had to be non-negative. But the spec is not clear to me.

8.2.7 tts:extent says: "...the initial value of the style property [auto] must be considered to be the same as the root container extent." Does this mean that it literally takes the value of the width and height of the root container, or does it mean that it is set to whatever area remains to the right and bottom of the origin contained entirely within the root container?

It additionally says: "If a specified value of this attribute is not supported, then a presentation processor must interpret the attribute as if the value auto were specified." If a region can exceed the area of the root container, then what value(s) are not supported exactly?  It would currently be implementation dependent, and thus could be clipped by a presentation processor to be the root container or not at all or something inbetween.

Whether regions are clipped to be within the root container or not changes the flow behavior considerably (and thus the visible presentation), so leaving it to be implementation dependent seems non-interoperable.
Received on Friday, 7 September 2012 17:46:26 UTC

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