Re: [css-transitions] Animation of paint servers

On Thursday 2013-04-18 10:37 -0700, Tab Atkins Jr. wrote:
> On Thu, Apr 18, 2013 at 10:32 AM, Dirk Schulze <dschulze@adobe.com> wrote:
> > Hi,
> >
> > CSS3 Transitions defines animations of paint servers [1]:
> >
> > ""
> >         • paint server (SVG): interpolation is only supported between: gradient to gradient and color to color. They then work as above.
> > ""
> >
> > This seems to be incompatible with the current model of SVG resources and SVG animation. Currently elements themselves can have triggered animations. It is not possible in SVG at the moment to make a style change on one element affect the content (DOM or SVGDOM) of another one.  From the author perspective it might seems quite plausible. However, it needs more discussion and specification work in the SVG WG and SVG specification. Since animations are from one url to another url, it is unclear how it could be specified at all and how the intermediate results affect the two resources.
> >
> > I would suggest that CSS Transitions treats paint server references the same as keywords. Note that paint servers are just <linearGradient>, <radialGradient>, <pattern> and possibly <color> elements. The animation of CSS colors on 'fill' and 'stroke' won't be affected and still work as described in the spec.
> >
> > The feature can be added to a future version of the spec when we outlined this concept.
> 
> Given that you can't construct an intermediate value between two
> references, I agree with this.  They should fall into the generic
> "image" bucket, which transitions with cross-fade() (this transition
> behavior is defined in Images 4, not Transitions).
> 
> When an SVG paint server is literally a color, not a referenced to a
> <solidColor> element, it should transition as a color, though.

This seems reasonable to me.  Is it compatible with implementations?
I believe the old wording dates back to the original Apple
transitions proposal.

-David

-- 
𝄞   L. David Baron                         http://dbaron.org/   𝄂
𝄢   Mozilla                          https://www.mozilla.org/   𝄂
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