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Re: [css3-transforms] ...calcMode

From: Dr. Olaf Hoffmann <Dr.O.Hoffmann@gmx.de>
Date: Mon, 4 Jun 2012 13:29:11 +0200
To: public-fx@w3.org
Message-Id: <201206041329.11489.Dr.O.Hoffmann@gmx.de>
Dirk Schulze:

...
> >> Even SMIL animations does not differ on further
> >> definitions for e.g calcMode and just uses 'from-to'.
> >
> > No, as mentioned calcMode cares in general about interpolation between
> > values from a list, not just from-to. Obviously one has to analyse the
> > complete list at once to get the default calcMode behaviour right.
> > But because between all transform values following section 15 one can
> > interpolate somehow if required, a values list does not cause more
> > complications (different from for example fill and stroke with possible
> > paint servers, implicating only discrete behavior).
>
> For paced animations I would agree. The definition on error handling for
> SVG says that it should get animated since the first error. E.g for
> values="translate(20) ; translate(100) ; translate(invalid)"
> calcMode="linear" you would see an animation from 20 to 100. See SVG 1.1
> error processing: "If the document has animations, the animations shall
> stop at the point at which an error is encountered and the visual
> presentation of the document shall reflect the animated status of the
> document at the point the error was encountered."
>

This is not related to error management, the calcMode definition
notes:
'The default mode is "linear", however if the attribute does not support 
linear interpolation (e.g. for strings), the calcMode attribute is ignored 
and discrete interpolation is used.'

Unfortunately for fill and stroke for example SVG is more complex
than intended by SMIL, but obviously we do not want only discrete
animation for fill and stroke, just because these properties are overloaded 
with non interpolable values like none or a paint-server. 
Therefore the viewer has to analyse the complete values list do decide, 
if something different than discrete is possible. 
The situation here seems to be slightly better, if we assume, that
some wording problems are fixed as suggested, linear or spline interpolation
seems to be always possible for such transform lists.

Olaf
Received on Monday, 4 June 2012 11:29:45 GMT

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