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Re: [css3-animation] keyframes without animations

From: Andras Nemeseri <andris@nemeseri.com>
Date: Thu, 14 Jan 2010 09:36:47 +0100
Message-ID: <2c2719261001140036o5df45304uc64e2dbd85efc4d9@mail.gmail.com>
To: Simon Fraser <smfr@me.com>
Cc: Sylvain Galineau <sylvaing@microsoft.com>, "www-style@w3.org" <www-style@w3.org>
"We have considered the ability to specify stepwise timing functions (e.g.
step-start, step-end or somesuch) to address this use case."

Adding stepwise timing function(s) would be a nice and working solution.
Do I need to submit a more formal request now?

(Simon: sorry for the multiple mail, I have forgotten to add the list and
Sylvain)

On Thu, Jan 14, 2010 at 12:26 AM, Simon Fraser <smfr@me.com> wrote:

> On Jan 13, 2010, at 3:02 PM, Sylvain Galineau wrote:
>
> >>
> >> If you set the animation-duration to 0 there will be no movement at
> >> all. Because the animation "loop" will be finished in 0 second.
> > Hmm. That was not my expectation based on the semantics of zero duration
> > with transitions but you seem to be right. Zero means the animation never
> > starts vs. going to the last frame immediately.
> >
> > A zero second completion should not result in no animation of the
> property
> > value, it should result in an immediate update i.e. by default, CSS
> properties
> > have a zero duration and take their new value as you update them.
>
> But animations have no effect once they complete. So, logically, a
> zero-duration animation snaps to the last keyframe and then reverts back to
> its original appearance instantaneously. Practically, it's as if the
> animation never runs.
>
> Note that if we add "fill modes", then a zero-duration animation could have
> a visible manifestation.
>
> >
> >> You said:
> >> "tou can set animation-duration of 0 and animation-delay of 1s on each
> >> frame"
> >>
> >> How can I set animation-duration or animation-delay on each frame? The
> >> specification says that the "animation-timing-function" is the only
> >> animation related css property which can be set on keyframes:
> >> http://www.w3.org/TR/css3-animations/#animation-timing-function_tag
> >
> >
> > My bad, yes you're of course correct. The duration - and the other
> properties -
> > apply to the entire animation. You will thus be unable to achieve the
> effect
> > you want without specifying a positive duration.
> >
> > Going through these three steps in a way that is visible to the user not
> only
> > implies but requires a specific duration anyway.
> >
> > So what you want to control is the easing function i.e. you want one that
> updates
> > the property value at the very end of the frame period. I am not sure
> whether this
> > can be specified using the cubic-bezier() function...
>
> It cannot. We have considered the ability to specify stepwise timing
> functions (e.g.
> step-start, step-end or somesuch) to address this use case.
>
> Simon
>
>
>
Received on Thursday, 14 January 2010 08:43:54 GMT

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