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Re: Animations issues (was Re: [CSSWG] Minutes Telecon 2012-12-12)

From: Brian Birtles <bbirtles@mozilla.com>
Date: Thu, 20 Dec 2012 10:58:28 +0900
Message-ID: <50D270C4.3000409@mozilla.com>
To: www-style@w3.org
(2012/12/20 5:50), Sylvain Galineau wrote:
> We agreed at the time that such empty @keyframes rules would not run.

We discussed this resolution in the Web Animations call last week and 
wanted to ask for clarification on why such rules do not run.[1]

We wonder if it is worthwhile allowing such animations to run anyway for 
the following reasons:

i) If in a future version, animations can be sequenced and an animation 
with a 3s duration but no keyframes is included in a sequence, we think 
one would still expect it to delay the next animation in the sequence by 
3s. If it takes time, it seems reasonable to also fire events.

ii) In such a future scenario where sequencing and other synchronisation 
is possible, there are valid uses for empty animations--both to act as 
spacers in a sequence or simply to fire events at appropriate times for 
triggering other actions.

iii) We think it is useful to distinguish timing from the animation 
effect. If such a distinction is made then events are related to timing 
and should not depend on the animation effect.

In the Web Animations model, animations with no keyframes (and even 
those with no animation effect) still occupy time and fire events for 
the above reasons. If CSS decides otherwise that's not a major problem 
for us: the CSS bindings to Web Animations will simply require that no 
Animation object is created in that case. However, for the above 3 
reasons, we wanted to quickly query the rationale behind this decision.

Best regards,

Brian

[1] http://lists.w3.org/Archives/Public/public-fx/2012OctDec/0090.html
Received on Thursday, 20 December 2012 01:58:57 GMT

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