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[css3-background] should radii be capped?

From: Håkon Wium Lie <howcome@opera.com>
Date: Tue, 21 Jul 2009 22:23:29 +0200
Message-ID: <19046.9153.283508.809677@opera.com>
To: www-style@w3.org
I've run into an issue where the specification for border-radius seems
more limiting than necessary. Consider this test case and screenshot:


The top part of the screenshot shows how Opera's internal
implementation renders the test case, the bottom in Firefox 3.5.

I believe Firefox caps the radii as per the current specification [1]
which states:

  The sum of two adjacent radii may not be more than the width or
  height (whichever is relevant) of the box. If any sum exceeds that
  value, all radii are reduced according to the following formula

   <nasty formula deleted>

Opera, however, doesn't cap the radii but attempts to honor them. I
can see many uses for the elliptic expressions that this behavior
allows. The spec, instead, will leave us with many stadium-like
borders, as can be seen in the two leftmost Firefox renditions.

One added benefit of removing the cap is that the nasty formula can be


[1] http://www.w3.org/TR/2008/WD-css3-background-20080910/

              Håkon Wium Lie                          CTO °þe®ª
howcome@opera.com                  http://people.opera.com/howcome
Received on Tuesday, 21 July 2009 20:24:14 UTC

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