W3C home > Mailing lists > Public > www-style@w3.org > January 2012

Re: [css3-animations] Override of animation rule by !important

From: Øyvind Stenhaug <oyvinds@opera.com>
Date: Mon, 23 Jan 2012 14:30:50 +0100
To: "www-style@w3.org" <www-style@w3.org>, "Sylvain Galineau" <sylvaing@microsoft.com>
Message-ID: <op.v8jg5orkbunlto@oyvinds-desktop>
On Fri, 20 Jan 2012 17:14:18 +0100, Sylvain Galineau  
<sylvaing@microsoft.com> wrote:

> [Øyvind Stenhaug:]
>> On Fri, 20 Jan 2012 01:01:51 +0100, Sylvain Galineau
>> <sylvaing@microsoft.com> wrote:

>> > - Does the :hover transition starts from whatever intermediate value
>> > was last applied by colorChange?
>> I'm not sure, but presumably it should act the same as if the animation
>> were removed while in progress. If there is a transition, it should
>> probably start from the intermediate value. But maybe there shouldn't  
>> be a
>> transition at all.
>> > - What happens when the user hovers away? Transitioning back to a
>> > moving target is not easy nor is it clearly desirable. Nor would a
>> > reversal look appropriate.
>> The current Transitions draft says that "[i]mplementations must not  
>> start
>> a transition when the computed value of a property changes as a result  
>> of
>> declarative animation". This seems like such a case, though I think that
>> sentence could use some clarification. (If the property's "computed  
>> value"
>> changes due to an animation finishing or being aborted, like in the
>> previous question, does that count as a "result of declarative
>> animation"?)
> Well in this case the transition is started by a property update through
> :hover, not the animation. But the latter has been updating the computed
> value of color so, presumably, the state of the property at :hover time
> is our transition start?

This is about the first question, quoted further up, right? I.e. the case  
where :hover starts applying? If so, then yes, some value between red and  
green would be the start value. *If* there should be a transition at all.

If you try changing the style of an element from "animation: colorChange  
4s; transition: color 1s;" to "animation: none; transition: color 1s;"  
while the animation is ongoing, Gecko will transition, but WebKit will  
not. When allowing the animation to run to completion, neither will  

> Once :hover no longer matches, we can't really reverse to the start value
> if the latter should resume its animation. I can't think of a good  
> solution
> that does not involve stopping the animation as soon as the transition  
> starts.

Once :hover no longer matches the animation applies, and to me this seems  
like a case where "the computed value of a property changes as a result of  
declarative animation". So if you want a transition to start then, I think  
the Transitions spec will have to be changed.

If you try changing the style of an element from "animation: none;  
transition: color 1s;" to "animation: colorChange 4s; transition: color  
1s;", neither Gecko nor WebKit will transition.

Øyvind Stenhaug
Core Norway, Opera Software ASA
Received on Monday, 23 January 2012 13:31:28 UTC

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