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Re: CSS3 Color: Interaction of opacity and rgba [css3-color]

From: L. David Baron <dbaron@dbaron.org>
Date: Mon, 2 Jun 2008 16:56:34 -0700
To: "REFSTRUP,JACOB (HP-Vancouver,ex1)" <jacob.refstrup@hp.com>
Cc: "www-style (www-style@w3.org)" <www-style@w3.org>
Message-ID: <20080602235634.GA30123@pickering.dbaron.org>

On Wednesday 2003-07-23 20:44 -0400, REFSTRUP,JACOB (HP-Vancouver,ex1) wrote:
> I had a question around opacity and rgba and their interaction based on the
> CSS3 Color module. Suppose the following style sheet:
> 
> span { 
>   color: rgba(100%,0,0,0.5);
>   opacity: 0.1
> }
> 
> Does both "alpha" values apply? I.e. would the text inside a span render
> with an effective opacity of 0.05 onto its parents element?

I managed to find this comment despite its lack of the string
"css3-color" (which is in the spec's URL).

Both alpha values do apply (but through different mechanisms).

This is tested in the test suite:
http://dev.w3.org/CSS/css3-color-test-suite/src/t32-opacity-offscreen-with-alpha-c.xhtml

I don't think any change to the specification is needed.  It
describes the two features independently, since they are in fact
independent.

-David

-- 
L. David Baron                                 http://dbaron.org/
Mozilla Corporation                       http://www.mozilla.com/
Received on Monday, 2 June 2008 23:57:16 GMT

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