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Re: animate-elem-46-t.svg

From: Boris Zbarsky <bzbarsky@MIT.EDU>
Date: Wed, 09 Jun 2010 10:35:46 -0400
Message-ID: <4C0FA6C2.2060008@mit.edu>
To: "Dr. Olaf Hoffmann" <Dr.O.Hoffmann@gmx.de>
CC: www-svg@w3.org
On 6/9/10 8:57 AM, Dr. Olaf Hoffmann wrote:
> Boris Zbarsky:
>> Now the question I don't know the answer to is what SMIL actually does.
>
> It defines how to animate features:

Yes, yes.  Or at least it tries to define.

> I think, the host language has to explain, what the value is.

If you define "host language" broadly enough, yes.

> SMIL only explains how to get an animation effect function.

There's a lot more than that in the SMIL spec last I checked.  In 
particular, it talks about base and animated values, override 
stylesheets, etc.  Sure sounds to me like at least in the latter case 
the output of SMIL is strings, not values.

> The host language has to define, what attributes, properties and
> different units of values mean and how such units are related.

Is that true, though?  SMIL explicitly talks about attributeType="CSS" 
in terms of the override stylesheet and so forth; the behavior of that 
is defined by CSSOM and CSS, not by the host language.

> If such a values is more complex like a colour value or that of an
> svg:tranform, or lists of different lengths, the host language has to define
> the interpretation of those constructs, as SMIL and SVG do for colours,
> SVG for transform and for some complex list constructs like stroke-dasharray
> (the animation value lists can have different length, but because SVG defines
> how to interprete these lists as pattern, it is possible to construct a
> representation, that is interpolable).

Sure.

>> And as a specific example to guide discussion, if you use SMIL to
>> animate line-height, what should happen?
>
> This is a CSS property.

Yes, indeed.  I'm largely interested in the attributeType="CSS" case, 
since that's what the discussion is about.

> The CSS recommendation (or another using this property as well)
> has to define whether this is animatable or not.

Sure.  Say it is.  What should the behavior be when trying to animate it 
from "1" to "2", given that line-height accepts both numbers and lengths 
and they mean _different_ things?

-Boris
Received on Wednesday, 9 June 2010 14:36:21 GMT

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