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Re: [css3-animations] Multiple animations affecting the same property

From: Øyvind Stenhaug <oyvinds@opera.com>
Date: Fri, 23 Sep 2011 15:16:39 +0200
To: "L. David Baron" <dbaron@dbaron.org>
Cc: www-style@w3.org
Message-ID: <op.v19i51ngbunlto@oyvinds-desktop>
On Thu, 22 Sep 2011 18:49:39 +0200, L. David Baron <dbaron@dbaron.org>  
wrote:

> On Thursday 2011-09-22 17:14 +0200, Øyvind Stenhaug wrote:
>> On Thu, 22 Sep 2011 16:36:15 +0200, Øyvind Stenhaug
>> <oyvinds@opera.com> wrote:
>>
>> >http://dev.w3.org/csswg/css3-animations/#animations
>> >
>> >"In the case of multiple animations specifying behavior for the
>> >same property, the animation defined last will override the
>> >previously defined animations."
>> >
>> >I found this rather unclear. It should probably say something like
>> >
>> >"If at one point in time there are multiple animations specifying
>> >behavior for the same property, the animation whose name occurs
>> >last in the value of 'animation-name' will override the other
>> >animations at that point."
>>
>> Actually, might need to qualify that sentence further, since it
>> should presumably only be about animations that actually apply (are
>> associated with valid keyframes).
>
> I'm not sure what you mean by "are associated with valid keyframes"
> -- but I think it might be wrong.  (I originally misunderstood the
> spec here, since it's *extremely* unclear.)

I suppose I ended up being unclear myself. I probably should just have  
said "are associated with a valid @keyframes rule". The term "apply" was  
 from this sentence in the spec: "An animation applies to an element if the  
element has a value for ‘animation-name’ that references a valid keyframes  
rule."

In other words I just meant that it should be clear whether, for example,  
animation "two" should override animation "one" at 50% here:

@keyframes one { from { color: blue } to { color: silver } }
@keyframes two { invalid { color: red } to { color: yellow } }
<div style="animation: one 1s, two 1s">test</div>

That's assuming that a "valid keyframes rule" must be parsable as a  
'keyframes-rule' per the syntax, and that (my interpretation of) the spec  
is on the right track to begin with (I guess another possibility would be  
to drop individual keyframes somehow, similar to how regular rulesets  
work).

> The set of properties
> that an animation applies to doesn't change over the course of an
> animation.  See
> http://lists.w3.org/Archives/Public/www-style/2011Apr/0381.html
> and other messages in that thread.

This seems to be the same case as point (1) in Sebastian Markbåge's reply.

-- 
Øyvind Stenhaug
Core Norway, Opera Software ASA
Received on Friday, 23 September 2011 13:17:17 GMT

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