W3C home > Mailing lists > Public > www-svg@w3.org > January 2002

SVG 1.1, animation on <use> question and suggestion

From: Antoine Quint <antoine@graougraou.com>
Date: Mon, 14 Jan 2002 11:59:41 +0100
To: <www-svg@w3.org>
Message-ID: <000001c19cea$919d73e0$4a0510ac@latitude324>
Hey there,

Congrats on the 1.1 specs, I think it's on the right track. I noticed a
bit that tickled my curiosity... In the SVG Mobile spec, section 4, "the
'use' element", it reads:

"Note that, in SVG 1.1, animations on a referenced element will cause
the instance to be animated. SVGB and SVGT also support this feature."

First thing, I don't think I have seen any mention of this change of
behaviour in the SVG 1.1 spec. Shouldn't it appear there too?

Let's assume I got it right and that "referenced element" are elements
like <symbol> (among others). SVG 1.0 had all <use> instances animated
if the referenced element was itself animated. SVG 1.1 apparently
introduces a change since only a particular instance will be animated.
This, I think, raises a couple issues:

  - backward compatibility: SVG 1.0 documents would not render the same
in a version-aware 1.1 user agent.
  - can we actually say in a definite way which behaviour of this
ambiguous situation is the correct one? I think both behaviours can be
useful.

How could we sort this out as syntax goes? Maybe we could introduce a
new SMIL-type "instance" keyword in the "attributeName" attribute. Then
an animated symbol would look like:

<!-- this would animate an instance of myRect -->
<symbol id="myRect">
  <rect ...>
    <animate attributeName="instance.y" ... />
  </rect>
</symbol>

... or

<!-- this would animate all instances of myRect, default SVG 1.0
behaviour -->
<symbol id="myRect">
  <rect ...>
    <animate attributeName="y" ... />
  </rect>
</symbol>

I think this way we could insure SVG 1.0 backward compatibility while
having both behaviours available. In any way, I think we need to find a
way to easily reference an animated object in 1.1.

Since we're on the animation topic, I was wondering why there was no
mention of the "prev" animation keyword in the SVG 1.0 Animation
chapter. Thanks,

Antoine

========================
Antoine Quint, Software Engineer
ILOG, R&D Visualization
+33 (0)1 49 08 89 56 
aquint@ilog.fr
Received on Monday, 14 January 2002 06:01:42 GMT

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