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Re: [css-animations] How animation-timing-function in keyframe rule interacts with direction

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Sat, 18 Oct 2014 00:05:22 -0700
Message-ID: <CAAWBYDCDC3NA-XRScYn9O8dc0gV-sfCUc=y4i982-6jFpeESJg@mail.gmail.com>
To: Simon Fraser <smfr@me.com>
Cc: Sylvain Galineau <galineau@adobe.com>, "<www-style@w3.org>" <www-style@w3.org>
On Fri, Oct 17, 2014 at 7:09 PM, Simon Fraser <smfr@me.com> wrote:
> On Oct 16, 2014, at 2:47 PM, Sylvain Galineau <galineau@adobe.com> wrote:
>> We should resolve the issue raised by dbaron [1] (Bug 14805 [2])
>>
>> If we have:
>>
>>       @keyframes timings {
>>               25% { animation-timing-function: linear; }
>>               40% { animation-timing-function: ease-out; }
>>       }
>>
>> ..then when the animation moves forward we expect linear to apply between 25% and 40%. But if the animation is moving backward e.g. due to an animation-direction: alternate then we also want linear to apply between 40% and 25%.
>>
>> Objections?
>>
>>
>> [1] http://lists.w3.org/Archives/Public/www-style/2011Mar/0744.html
>> [2] https://www.w3.org/Bugs/Public/show_bug.cgi?id=14805
>
>
> I don’t think that’s right. The reverse animation should be a mirror-image of the forward animation, so the reverse animation should be linear for the last 25% of its travel.

Maybe you misread?  The forward animation is not linear in its first
25%, it's whatever the 'animation' property sets as its timing
function.  The forward animation is linear between 25% and 40%, so the
reverse animation should be linear between 40% and 25% (counting
backwards).

~TJ
Received on Saturday, 18 October 2014 07:06:09 UTC

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