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RE: multiple animation-targets etC

From: Patrick Schmitz <pschmitz@microsoft.com>
Date: Tue, 28 Nov 2000 11:16:38 -0800
Message-ID: <6CAC6551F8C10F4C9EC0CF34132F2AAE4FCB54@red-msg-07.redmond.corp.microsoft.com>
To: "'Tobias Reif'" <tobiasreif@yahoo.com>, "'www-svg@w3.org'" <www-svg@w3.org>
Cc: "'symm@w3.org'" <symm@w3.org>
Hi Tobias -

Thanks for your interest. Comments inline (copying symm list as well)

> -----Original Message-----
> From: Tobias Reif [mailto:tobiasreif@yahoo.com]
> Sent: Thursday, November 23, 2000 2:09 PM
> To: 'www-svg@w3.org'
> Subject: multiple animation-targets etC
> 
> 
> Hi!
> 1)
> What was the reason to restrict the number of
> target-values in the xlink:href-attribute in the
> animate element?
> CR 2000-nov-02:
> 19.2.4 "Attributes to identify the target element for
> an animation" :
> "<uri> must point to exactly one target element which
> is capable of being the target of the given animation.
> If <uri> points to multiple target elements,[...],
> then the document is in error"
> I can't find this restriction neither in SMIL1 nor
> SMIL2. (and even if so:)

SMIL 1 did not support animation. SMIL 2 does, and has the same constraint
as you note, for reasons of simplicity in the model.

Nevertheless, I have run across this as well, and think it is worth
considering in a future version of SMIL Animation.

> 
> 2)
> Could this become a canditate for inclusion into SVG2?
> Together with the requirement for implementations to
> support full Xpointer, loads of redundant code could
> be saved.

We can certainly talk about it. As there are no specific plans for the next
version of SMIL Animation beyond SMIL 2.0, we cannot make any commitments.

> 
> 3) I would like to be able to pause an animation, and
> the let it resume. I'm not yet proficient, but as far
> as I see, currently it's only possible to restart an
> animation, or in other words say "play from start",
> not "go on".

In SVG this is true. In (other) SMIL languages that include animation, you
have some syntactic mechanisms to achieve this. See the discussion of the
<excl> element and its pause  semantics in the SMIL 2.0 Timing modules.

While we have deferred work on the DOM specification for SMIL, pause and
resume methods are certainly among our priorities for this area. 

> 
> 4)
> Also, a short notation to control all ongoing
> animations at once would be handy (like "pause" and
> "play" in the rightclick-menu of the adobe-viewer)
> :
> "pause all"; "resume all"; "reset all"; "slomo
> forward"; "fast forward"; "slomo backward"; "play
> backwards"; "fast backward" ...

This would be achieved by controlling (i.e. pausing and resuming) the time
container for the associated animations. In SVG, there are no specified time
containers as in other SMIL languages. Nevertheless, this is equivalent to
having the body element (or equivalent in a particular language) defined
with SMIL <par> semantics.

You can get some sense of this by using the animation features in the
XHTML+SMIL language, as supported by MS IE 5.5. This includes time
containers and other features of SMIL 2.0. Unfortunately, pause and resume
have a nasty side-effect for animation, as required by a related feature for
media - when paused, the effect of the animation is removed. You can work
around this by just animating the speed to a very small value (yes, a hack,
but workable). I can provide some pointers if you are interested.

> 
> 5)
> http://www.w3.org/TR/smil-animation/
> :
> "While this document defines a base set of animation
> capabilities, it is assumed that host languages may
> build upon the support to define additional or more
> specialized animation elements. "

Not sure what your point is here. 

Patrick Schmitz
Researcher - Telepresence and Ubiquitous Media
Microsoft
Received on Tuesday, 28 November 2000 16:45:56 GMT

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