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Re: [css3-transitions] Back-tracking transition-timing-function

From: L. David Baron <dbaron@dbaron.org>
Date: Mon, 7 Jun 2010 17:22:44 -0700
To: Simon Fraser <smfr@me.com>
Cc: Erik Arvidsson <arv@chromium.org>, Alex Meiburg <timeroot.alex@gmail.com>, www-style@w3.org
Message-ID: <20100608002244.GA7207@pickering.dbaron.org>
On Thursday 2010-05-06 00:05 -0700, L. David Baron wrote:
> On Wednesday 2010-05-05 23:46 -0700, Simon Fraser wrote:
> > We modeled transition/animation timing functions after SVG keySplines:
> > http://www.w3.org/TR/2001/REC-smil-animation-20010904/#KeySplinesAttribute
> > 
> > which limit the values between 0 and 1.
> > 
> > We'd be OK lifting this restriction for CSS (assuming people are
> > happy with the divergence from SVG), but we'd have to make some
> > rules about how properties like color get clamped when you go
> > outside the 0->1 range.
> 
> There is a relationship between this discussion and the discussion
> about reversing transitions.  I currently have an unlanded patch
> that vastly simplifies (by avoiding dependence on distance
> computation) Gecko's handling of reversing of transitions using
> inversion of the transform timing function.
> 
> Then again, we need the distance computation for SMIL, so I could
> perhaps leave it as-is, although I really don't want to figure out
> how to write a distance computation function for transforms.

Actually, I don't depend on inversion of the timing function for
this new reversing code.

Second, I've heard other requests for this feature, so I would
strongly support relaxing the range restriction for the y1 and y2
values.

(I don't think the value clamping is anything we don't already have
to do for SMIL additive animations, although maybe that doesn't
cover quite as many value types.)

-David

-- 
L. David Baron                                 http://dbaron.org/
Mozilla Corporation                       http://www.mozilla.com/
Received on Tuesday, 8 June 2010 00:23:18 GMT

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