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[css3] box-shadow specification bug

From: Andrew Fedoniouk <news@terrainformatica.com>
Date: Thu, 4 Apr 2013 20:58:38 -0700
Message-ID: <CALRQH79SMpDT8e8dKahNiHDsUmo56PodSyMsokxh3EhNOuT9Vw@mail.gmail.com>
To: "www-style@w3.org" <www-style@w3.org>
Please check this sample in Google Chrome and Firefox:
http://terrainformatica.com/w3/box-shadow-outer.htm

Note top corners in first and second div's.

FF renders this according to the spec and so it demonstrates bug in the
specification.

In these two divs top/right border radius has these values:
0.001px and 0.1px

The rendering is dependent to particular UA rounding rules.
So R=0.001px is considered as zero radius in FF
and 0.1px is not.

So together with the requirement "For corners with a zero border-radius,
however, the corner must remain sharp" the spec also shall have a notion
of zero border-radius and/or calculation precision and how exactly
to measure sharpness.

Chrome renders this against the spec but mathematically correct,
distance there is distance - all points with similar color lie on the same
distance from the border, no matter what radius is used
and so this implementation is stable to rounding problems, floating
point precision, etc.

Please consider removing  "For corners with a zero border-radius,
however, the corner must remain sharp" statement from the spec.

Spec reference: http://www.w3.org/TR/css3-background/#the-box-shadow

-- 
Andrew Fedoniouk.

http://terrainformatica.com
Received on Friday, 5 April 2013 03:59:06 UTC

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