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Re: Comments on CSS Transitions

From: Doug Schepers <schepers@w3.org>
Date: Fri, 27 Feb 2009 12:59:04 -0500
Message-ID: <49A829E8.7040306@w3.org>
To: www-style@w3.org
CC: www-svg@w3.org
Hi, Tab-

Tab Atkins Jr. wrote (on 2/27/09 11:51 AM):
> On Thu, Feb 26, 2009 at 11:16 PM, Cameron McCormack<cam@mcc.id.au>  wrote:
>>   Only animatable CSS properties can be transitioned.
>>
>>  Why are some properties defined as animatable and others not?  In SVG
>>  1.1, all CSS properties are animatable, however Transitions defines only
>>  certain SVG properties as being animatable.  Why not use the property
>>  definitions from SVG to determine whether a transition can be applied
>>  to that property?  (Although in SVG Tiny 1.2 there are two properties
>>  that aren't animatable[2], this seems like an oversight to me.  And I
>>  guess that allowing transition-duration, etc. to be transitioned would
>>  be... interesting. :))
>
> Because many properties simply don't have a sensical transition.  For
> example, transitioning from position:static to position:relative, or
> display:block to display:inline.

That's true for transitions.  However, for declarative animation in 
general, it's perfectly reasonable to "animate" (that is, change the 
computed value declaratively) those properties.  In SVG/SMIL, if there 
isn't a sensible way to transition from one state to another, the 
animation is simply a quantum state change.  That doesn't mean it's not 
animatable, just not transisitionable.  (Yay, I made up a new word!)


> Even one that could possibly make
> sense, like display:block to display:none, still has way too many
> variables to be implementable.  It's *actually* an opacity animation,
> or a height animation, or what have you.

I would say those are 3 different animations, with different effects.


Regards-
-Doug Schepers
W3C Team Contact, SVG and WebApps WGs
Received on Friday, 27 February 2009 18:00:17 GMT

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