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Re: CSS3 module: Color

From: Chris Lilley <chris@w3.org>
Date: Thu, 27 Feb 2003 11:59:50 +0100
Message-ID: <3569357859.20030227115950@w3.org>
To: Bert Bos <Bert.Bos@sophia.inria.fr>, www-style-request@w3.org, "Jonathan Stanley" <jon@asciigrackle.eclipse.co.uk>
CC: www-style@w3.org

On Thursday, February 27, 2003, 3:58:40 AM, Jonathan wrote:

JS> Hi

JS> Had a good little read from a users point of view, and quite excited about
JS> some of the things it'll bring (though how soon browsers support it is a
JS> slightly different matter :( )

JS> Anyway, I see within the RGB(A) model, the valid ranges are defined in
JS> section 4.2.2:

JS> ---
JS> em { color: rgb(255,0,0) }      /* integer range 0 - 255 */
JS> em { color: rgba(255,0,0,1)     /* the same, with explicit opacity of 1 */
JS> em { color: rgb(100%,0%,0%) }   /* float range 0.0% - 100.0% */
JS> em { color: rgba(100%,0%,0%,1) } /* the same, with explicit opacity of 1 */
JS> ---

JS> If R, G and B can have values from 0.0% to 100.0% percent, then why is A,
JS> alpha, so limited within the bounds of 0.0 to 1.0, equivanlent to 0% to 100%
JS> in 10% steps.

The precision is not limited to 10% steps. It can be any value, for
example 0.123456

JS> There also isn't bounds for values when using the HSL(A) colour model, other
JS> than definition of hue, that 0 = 360, no definition of how negative values
JS> are handled, eg:

JS> * { color: hsl(-240, 100%, 50%) }

JS> ... or going round "more than once" in the colour wheel:

JS> * { color: hsl(840, 100%, 50%) }

I agree that this aspect should be more clearly specified. It seems
obvious that hue is a wraparound value but for consistency of
implementation, it should be explicitly stated.

JS> Then the "currentColor" property which is treated as "inherit" at parse
JS> time, would be better hypenated? That is: "current-color"

There is an issue with hyphens in names, to do with scripting. In
response to a request from the DOm working group, SVG WG changed all
the names that it had to camelCase, except for existing CSS names that
we did not control.

Since the currentColor value comes from SVG, that is why it uses

It has been in SVG since 1999 and is implemented in 15 or so different

Thanks for your comments.

 Chris                            mailto:chris@w3.org
Received on Thursday, 27 February 2003 05:59:56 UTC

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