Re: [csswg-drafts] [web-animations-1] Fixed play animation procedure for scroll animations (#2075) (#5059)

Ok, please help me try to understand. I believe Kevin is suggesting that simply resetting the hold time when setting the start time is enough to fix both problems? Is that correct? Olga, does that work?

> > (And the more I think about it, the more I wonder if the pending playback rate actually needs to be applied asychronously for play() anyway? I'm having trouble thinking of a scenario where it would make a difference?)
> 
> Applying pending playback rate asynchronously makes a difference when reversing or calling updatePlaybackRate() on running animation. In these cases play pending task needs both the current and pending playback rates to recalculate start time to match the current time.

Oh, good point.

> I was thinking more about diverging play procedure for scroll animations to call set start time. I feel like this inconsistency is "more inconsistent" than applying pending playback rate.

I'm not quite sure I follow. Does this mean that you prefer we _don't_ call the "set start time" procedure but just directly apply the pending playback rate? Is there anything in particular that you feel is better about that?

(I'm wondering if calling the "set start time" procedure is better since we skip the pending state, and that's better since the UA doesn't actually have any time values to resolve asynchronously?)

> How about we generalize updating playback rate asynchronously only when it's needed? In this case the condition will be:
> 
>     * If _performed seek_ is true or _hold time_ is resolved,
>       
>       * Apply any pending playback rate on animation.

That's interesting. What would that help with?

In any case, I still want to refactor this to make step 5 simply set a local _seek time_ variable, and then, as a separate step, update either the hold time or start time based on the value of _finite timeline_. Once we do that, it would be easier to clear the pending playback rate there too if we decide to do that.

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Received on Friday, 22 May 2020 04:26:15 UTC