W3C home > Mailing lists > Public > www-style@w3.org > February 2012

RE: [CSS3-images] premultiplied alpha (was rotate(<angle>[, <translation-value>, <translation-value>]))

From: Brian Manthos <brianman@microsoft.com>
Date: Tue, 21 Feb 2012 19:56:43 +0000
To: Rik Cabanier <cabanier@gmail.com>, "L. David Baron" <dbaron@dbaron.org>
CC: Tab Atkins Jr. <jackalmage@gmail.com>, www-style list <www-style@w3.org>
Message-ID: <9710FCC2E88860489239BE0308AC5D170EC5B299@TK5EX14MBXC266.redmond.corp.microsoft.com>
Rik: 
> Well, you *could* special case 'transparent' to say use a transparent version
> of the previous or next color stop which is really what the author means.

This was also discussed in depth and had concerns.

Some of the concerns:
- "special case of 'transparent'": animations and transitions become incredibly complex with no "correct" answer in at least some situations
- "use the transparent version of the previous or next stop": well which one?  Or is it both depending on situation?
- "what the author means": any spec that implies the editor knows what the author means is usually wrong in its generic boldness
 
+1 @ my posts about improving "memory" coming out of this forum.



L. David Baron:
> Choosing premultiplied means optimizing for the normal case rather
> than the odd feature of transition to transparent + color.

Rik:
> I don't think going from red to transparent yellow is an odd case at all. It
> gives you a similar effect to InDesign's gradient feather.

I think it's a reasonable scenario but also reasonable for CSS to draw the line somewhere regarding what to support directly.

The PROs and CONs of { (a) premultiplied, (b) not premultiplied, and (c) both available } were discussed in depth multiple times and the conclusion (to my recollection CSSWG resolution) was to go with (a) for CSS3.  There was some gnashing of teeth in response, but mostly localized to a few voices. 
Received on Tuesday, 21 February 2012 19:57:57 GMT

This archive was generated by hypermail 2.3.1 : Tuesday, 26 March 2013 17:20:50 GMT