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[css-animations] Clarification of events with zero-duration intervals

From: Brian Birtles <bbirtles@mozilla.com>
Date: Thu, 03 Jul 2014 11:32:19 +0900
Message-ID: <53B4C0B3.8000702@mozilla.com>
To: "www-style@w3.org" <www-style@w3.org>
Hi,

In the current draft of CSS Animations we have both:

  (4.3 The animation-duration property)
  "If the <time> is 0s, like the initial value, the keyframes of the
   animation have no effect, but the animation itself still occurs
   instantaneously. That is, animation-fill-mode applies as normal,
   filling backwards or forwards as appropriate, and animation events
   still fire."
   http://dev.w3.org/csswg/css-animations/#propdef-animation-duration

And later:

  (5 Animation Events)
  "Any animation for which both a valid keyframe rule and a non-zero
   duration are defined will run and generate events; this includes
   animations with empty keyframe rules.
  "Issue: This contradicts the animation-delay section, which says that
   a 0s duration animation still fires events."
   http://dev.w3.org/csswg/css-animations/#events

I believe 4.3 is correct and is now consistently implemented in all 
major browsers.[1] Is there any reason not to fix the second reference 
to simply drop the "non-zero duration" condition?

Best regards,

Brian

[1] We fixed this in Firefox only recently: 
https://bugzilla.mozilla.org/show_bug.cgi?id=1004365
See https://bug1004365.bugzilla.mozilla.org/attachment.cgi?id=8415743 
for a test case
Received on Thursday, 3 July 2014 02:32:39 UTC

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