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Re: [CSS4 color][CSS4 transition] color pre-multiplied vs non pre-multiplied

From: Alan Gresley <alan@css-class.com>
Date: Fri, 01 Feb 2013 19:29:14 +1100
Message-ID: <510B7CDA.1040002@css-class.com>
To: Rik Cabanier <cabanier@gmail.com>
CC: Simon Fraser <smfr@me.com>, fantasai <fantasai.lists@inkedblade.net>, "www-style@w3.org" <www-style@w3.org>
On 1/02/2013 6:23 PM, Rik Cabanier wrote:
> On Thu, Jan 31, 2013 at 11:18 PM, Simon Fraser <smfr@me.com> wrote:
>
>> We rely on Core Graphics to render gradients on Mac, and that can't do
>> pre-multiplied. That's the main reason why gradients don't match
>> transitions.
>>
>
> Yes, this is probably why FireFox is also not matching (and canvas and SVG
> are also not premultiplied)

Regarding SVGs, WebKit does something different with SVG. If only a 
transparent color is used (i.e. stop-color:rgba(255,0,255,0)), the SVG 
is premultiplied. This changes if you add stop-opacity:0. FF, Opera and 
IE9 behave the same way for both methods.

The later of the following two test has stop-opacity:0.

http://css-class.com/test/svg/multiplied.xml

http://css-class.com/test/svg/multiplied2.xml


-- 
Alan Gresley
http://css-3d.org/
http://css-class.com/
Received on Friday, 1 February 2013 08:29:45 GMT

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