Re: [web-animations] compound longhand interpolation

On Sun, Oct 13, 2013 at 8:30 PM, Shane Stephens <> 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.


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