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RE: ISSUE-58 (showBackground animateable): shouBackground should not be animateable [DFXP 1.0]

From: Sean Hayes <Sean.Hayes@microsoft.com>
Date: Sun, 19 Apr 2009 10:26:13 +0100
To: "Glenn A. Adams" <gadams@xfsi.com>, Public TTWG List <public-tt@w3.org>
Message-ID: <AB3FC8E280628440B366A29DABB6B6E8070E507C3A@EA-EXMSG-C334.europe.corp.microsoft.com>
Interesting you should say that, I had exactly the same thought last night. One of the original design principles was that timed text display should be a function of time, i.e. without state. The reasoning behind having attributes non-animateable was that it might be too expensive in terms of re-flow etc, but if at each moment in time the entire tree is effectively made anew. Then this reasoning seems unsound.

So I support the motion.

The only one I have some doubts about is dynamicFlow, because it seems to operate somewhat outside the same timeline, and thus have state across time ticks. Which is also why I think dynamicFlow should be dropped, or substantially reworked in order to fit with the above model.

Sean Hayes
Media Accessibility Strategist
Accessibility Business Unit
Microsoft

-----Original Message-----
From: public-tt-request@w3.org [mailto:public-tt-request@w3.org] On Behalf Of Glenn A. Adams
Sent: 19 April 2009 7:11 AM
To: Public TTWG List
Subject: Re: ISSUE-58 (showBackground animateable): shouBackground should not be animateable [DFXP 1.0]

i propose we take a different approach: make all styles animatable

i note that at present, the following are defined as being non-animatable:

tts:direction
tts:displayAlign
tts:dynamicFlow
tts:extent
tts:origin
tts:overflow
tts:unicodeBidi
tts:writingMode

in contrast, all of the (remaining) following properties are defined as
animatable:

tts:backgroundColor
tts:color
tts:display
tts:fontFamily
tts:fontSize
tts:fontStyle
tts:fontWeight
tts:lineHeight
tts:opacity
tts:padding
tts:showBackground
tts:textAlign
tts:textDecoration
tts:textOutline
tts:visibility
tts:wrapOption
tts:zIndex

there doesn't seem to be any principled reason for making any of the above
properties non-animatable; in fact, we have recently assumed that tts:origin
(and perhaps tts:extent) is animatable in order to move a region to a new
location; also, the following seem to be inconsistent on the surface:

* tts:textAlign is animatable, but tts:displayAlign is not
* tts:wrapOption is animatable, but tts:overflow is not

if one supports animation for one property, then it should be fairly trivial
to support animation on any other property;

therefore, i propose we make all the style properties animatable, which will
make usage and authoring less subject to special case exceptions;

glenn

On 4/18/09 3:03 AM, "Timed Text Working Group Issue Tracker"
<sysbot+tracker@w3.org> wrote:

>
> ISSUE-58 (showBackground animateable): shouBackground should not be
> animateable [DFXP 1.0]
>
> http://www.w3.org/AudioVideo/TT/tracker/issues/58
>
> Raised by: Sean Hayes
> On product: DFXP 1.0
>
> tts:showBackground is listed in the specification as animateable. I cant see
> why this is necessary. Unless we have a use case for this I propose it be set
> to animateable: none
>
>
>
Received on Sunday, 19 April 2009 09:25:02 GMT

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