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Re: Agenda request: Presentation attributes in animation sandwich model

From: Brian Birtles <bbirtles@mozilla.com>
Date: Wed, 29 Feb 2012 11:05:48 +0900
Message-ID: <4F4D87FC.5090202@mozilla.com>
To: Alex Danilo <adanilo@google.com>
CC: Glenn Adams <glenn@skynav.com>, Dirk Schulze <dschulze@adobe.com>, "SVG WG (public-svg-wg@w3.org)" <public-svg-wg@w3.org>, "www-svg@w3.org" <www-svg@w3.org>
Hi Glenn and Alex,

(2012/02/29 9:14), Alex Danilo wrote:
> Hi Glenn,
> On Tue, Feb 28, 2012 at 7:30 PM, Glenn Adams <glenn@skynav.com
> <mailto:glenn@skynav.com>> wrote:
>     By "on top of" to you mean "has priority over"? The former
>     expression is vague, so please clarify.
> I think (correct me if wrong Brian) what he means is making the CSS
> animation be another layer in the SMIL sandwich model.

Yes, something of that ilk. At an abstract level, eventually I think we 
want different types of animations to be able to "add" their results 
together. For example, a rotation and a translation animation should be 
able to be defined independently, even have different timing, and yet be 

However, some types of "addition" are non-commutative (e.g. if you 
define the addition of transform operations as matrix 
post-multiplication), therefore an order is needed.

This ordering also becomes important if you allow the additive behaviour 
to vary on an animation-by-animation basis (e.g. some animations 
override, some add etc.)

By "on top of" I'm referring to the order of addition. In the long-term 
I don't think we want either CSS or SVG to be constrained as to where 
they appear in that order.

I'm not promoting imposing the SMIL sandwich model on CSS by any means. 
I'm just thinking out loud about what the implications might be of 
basing animation order on syntax. But like I said, even if we do that, I 
think we'll be able to add controls later that override it.

I'd be really keen to know what the parameters are that make H/W 
acceleration possible so we can work with that in mind too.

Best regards,

Received on Wednesday, 29 February 2012 02:06:26 UTC

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