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Re: [web-animations] compound longhand interpolation

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Tue, 15 Oct 2013 10:38:00 -0700
Message-ID: <CAAWBYDBf41KtVWvRDV4j3hZBws6iB5h74aOdPRMCz=ZkE8AfiA@mail.gmail.com>
To: Shane Stephens <shans@google.com>
Cc: "public-fx@w3.org" <public-fx@w3.org>
On Sun, Oct 13, 2013 at 8:30 PM, Shane Stephens <shans@google.com> wrote:
> What should the result of interpolating (e.g. for clip):
> rect(0px, 0px, 0px, auto)
> to
> rect(100px, 100px, 100px, 50px)
> be?

Ooh, this is a Transitions bug - it defines clip to interpolate as
"rectangle", which assumes that all of the values are numbers.  (Which
is even more wrong - they should interpolate as lengths.)

The obvious answer is that these two aren't interpolable (at
computed-value time), so the
rectangle should just flip.

> What about (e.g. for mask-box-image-slice):
> 50% fill
> to
> 30%

This needs to be defined by Masking.  Any property whose value is
non-trivial needs an Animatable line in its propdef table.

I suspect the obvious answer is that it should interpolate from 50% to
30%, and flip from filling to not filling, but I could see arguments
that it should just flip the entire thing.

> Should individual longhand properties with multiple 'channels' interpolate
> each channel separately (i.e. 0px can smoothly interpolate to 100px even
> while auto steps to 50px), or should a single non-interpolating channel
> block interpolation of all channels (i.e. fill -> not fill is a step, so 50%
> to 30% should step too)?

Defined by the longhand.  There's no general principle, as different
things make sense.  For example, shadows are only interpolable if both
are inset or both are outset.

~TJ
Received on Tuesday, 15 October 2013 17:38:47 UTC

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