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Re: [css3-background] border-radius color transitions using gradients recommended but undefined

From: Zack Weinberg <zweinberg@mozilla.com>
Date: Tue, 26 Jan 2010 09:51:17 -0800
To: W3C Emailing list for WWW Style <www-style@w3.org>
Message-ID: <20100126095117.568ee601@mozilla.com>
fantasai <fantasai.lists@inkedblade.net> wrote:
> On 01/25/2010 05:25 PM, Sylvain Galineau wrote:
> > Both the Candidate Recommendations [1] and the latest editor's
> > draft [2] currently state:
> >
> > "It is not defined what these transitions look like, but a gradient
> > is recommended for color transitions that don't involve dotted or
> > dashed borders."
> I'm not comfortable with normatively requiring a particular gradient
> form or a particular type of corner join in css3-background. I don't
> think we have clear answers as to what would look best--other than it
> should be a type of conic gradient--so I want to leave implementations
> free to experiment. It's fine IMO to leave this detail of border
> rendering undefined in CSS3: it gives it a chance to evolve as
> implementers learn from each other and from author feedback.

As an immediate practical problem, conic gradients are not a widely
available drawing primitive.  They're not in Postscript or PDF *at all*
as far as I know, which means they're not in Cairo, and I didn't find
them in a cursory look at the Windows and MacOS drawing APIs either.
It's probably not that hard with OpenGL shaders if you know what you're
doing, but I wouldn't know where to begin.

(Paging Andrew F: how'd you implement them in Sciter?)

Received on Tuesday, 26 January 2010 17:51:51 UTC

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