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Re: [css3-transitions]

From: Dr. Olaf Hoffmann <Dr.O.Hoffmann@gmx.de>
Date: Tue, 31 Mar 2009 13:30:42 +0100
To: www-style@w3.org
Message-Id: <200903311430.42775.Dr.O.Hoffmann@gmx.de>
Dean Jackson:

....
>
> > Is it ok to reference a wikipedia article, everyone
> > can change at any time in a draft/specification?
>
> I'll mark the link as informative.

I think, the formula is simple enough to write it
directly down in the draft, then no one has to
search around and the readability for non-experts
is improved. If someone wants to know more
about those curves and their history or other
applications, it should be simple anyway
to find those information just looking for the 
name...


>
> > 5. in section 4. it is not noted, how to animate
> > between keywords (they are mentioned
> > in 5. too). This will be the same as for
> > 'visibility'? Or are the keywords always
> > converted into numbers for the current
> > animatable properties (seems to apply
> > only to vertical-align).
>
> We'll have to define this for every keyword-based property. I'm not a
> big fan of these properties being animated anyway.
>

For transitions - as I understand it now - it does not look
very useful, indeed. For animations (well discrete animations
are not really available in the CSS animation draft) this is
different. 
Therefore the list of transitionable properties could be much
more restrictive than the list of animatable properties.

> > About paint-server - how to interpolate
> > between a radial and linear gradient?
> > Is the direction vector for linear gradients
> > interpolated too if different? Respectively
> > the cx, cy, fx, fy, r for a radial gradient?
> > What about gradientUnits, gradientTransform,
> > spreadMethod, xlink:href? Or is the interpolation
> > done for each pixel of the output separately?
> > I think, it needs some more explanations
> > how this should work.
>
> It's still up in the air how gradients should transition. For regular
> images, like background, they should probably crossfade (with the
> opacity used in the transition calculated by the timing function.. and
> the reverse for the outgoing image). 

- more fun, if width or height of the two images differ, with and without
background repetition and and implications on positioning and all 
those complications would require a quite long prose to define the 
same effect for all implementations unambiguously for such complex 
issues ...

> For gradients, in some cases it 
> might be possible to animate - if they are similar enough. They would
> have to be the same type and have the same number of stops. However,
> some people think they should just be treated like images and crossfade.
>

The last sounds simpler. Especially if an authors needs to animate the
gradient (SVG), this is already available for most compatible variants
with the SMIL/SVG method. And what is not compatible behaves typically
like a raster image concerning transition.
Else one gets even more fun specifing how to interpolate between two
animated gradients ;o)

Olaf
Received on Tuesday, 31 March 2009 12:32:59 GMT

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