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Re: [css-animations][web-animations] steps() timing function sometimes unintuitive

From: Rachel Nabors <rachelnabors@gmail.com>
Date: Tue, 08 Mar 2016 22:24:32 +0000
Message-ID: <CAPFA0t34A4PVehbkTB9Q76RFzyGAfuOMgFaF85M0DhuO8mU6pA@mail.gmail.com>
To: Brian Birtles <bbirtles@mozilla.com>, www-style list <www-style@w3.org>
Cc: "Tab Atkins Jr." <jackalmage@gmail.com>, "L. David Baron" <dbaron@dbaron.org>, "public-fx@w3.org" <public-fx@w3.org>
I was thinking of "steps(5, equal)" when discussing this syntax, as an
expansion of the steps() formula. I think it looks sensible, if that's
On Mon, Mar 7, 2016 at 9:00 PM Brian Birtles <bbirtles@mozilla.com> wrote:

> On 2012/12/21 3:46, Tab Atkins Jr. wrote:
> > On Wed, Dec 19, 2012 at 6:40 PM, L. David Baron <dbaron@dbaron.org>
> wrote:
> >> On Wednesday 2012-12-19 10:29 -0800, Tab Atkins Jr. wrote:
> >>> I propose another steps value: step-mid. It splits the animation curve
> >>> into n segments, makes the first n-1 do step-end behavior, and leaves
> >>> the last to just run normally.  The above example could instead be
> >>> written as "steps(4, step-mid)" and have this behavior:
> >>
> >> I like the idea, but I find the name confusing; it sounded like
> >> something that would give the first and last steps half the duration
> >> of the other steps.  (I also find the description quoted above
> >> confusing, but the rest of the email made it clear.)
> >
> > I have absolutely no attachment to the name.  It was the first thing
> > that came to mind.
> >
> > I assume that Rachel's suggestion comes from her association of
> > steps(n, end) with meaning "eat the end of the animation" (and
> > likewise for "start"), so "none" is reasonable in that sense.  I'm not
> > sure it makes sense if your understanding comes from the spec's
> > explanation, though, where "end" means "transitions all at once at the
> > end of the step".
> >
> > Another possibility is just a new function.  I'm not sure what I'd
> > want to name it, though.
> I spoke with Rachel and a few others about this recently and we were
> wondering about the name step-equal? Unfortunately, that doesn't
> translate into a function very well ('step-equal(2)'? Alternatively,
> what about 'step-stagger' and 'stagger(5)', or just the function?).
> I'd like to settle on this soon because Chrome is shipping
> Element.animate() with support for 'step-middle' as defined by Web
> Animations.[1] We went to implement this in Firefox[2] but I'm concerned
> that there aren't use cases for step-middle as currently specced and
> instead what we want is what Tab originally proposed in this thread.
> Assuming usage is low in Chrome, I'd like to drop step-middle from Web
> Animations and replace it with this revised timing function.
> Best regards,
> Brian
> [1] http://w3c.github.io/web-animations/#typedef-step-timing-function
> I didn't realize Chrome had implemented this, or else I would have
> brought this up sooner.
> [2] https://bugzilla.mozilla.org/show_bug.cgi?id=1248340
Received on Tuesday, 8 March 2016 22:25:13 UTC

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