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Re: Border Curvature Proposal

From: Lea Verou <lea@verou.me>
Date: Wed, 5 Aug 2015 19:17:21 +0300
Cc: www-style list <www-style@w3.org>
Message-Id: <738967F5-6AEE-4559-B252-2A26735A785D@verou.me>
To: Jacob Parker <jacobparker1992@gmail.com>

> On Jul 30, 2015, at 22:28, Jacob Parker <jacobparker1992@gmail.com> wrote:
> Negative border radii, as commonly suggested, doesn’t really make sense. I’ve seen a suggestion to have border radii styles, including normal, inverted, and flat (just a clipped corner). I think these could be achieved using superellipses, and would be much more flexible.
> Made a draft spec
> https://github.com/jacobp100/css-border-curvature

As Sebastian said, this is already planned for backgrounds-4 with a different syntax (corner-shape). However, it’s still useful to examine different options for this, as it’s still being worked on.

However, this proposal has several issues. 

Firstly, `curvature` is a rather academic term that most users will have difficulty with. Simple words please!

Most importantly, while the solution proposed is mathematically elegant (love how corner-shape’s curve, bevel and scoop are all achievable just by varying n), I’m afraid its usability is very problematic: Most CSS authors have severe trouble even with middle school level math. Actually, even many *distinguished* CSS authors have trouble with middle school level math, as I realized during the tech review rounds of my book. With this proposal, you need to be able to *graph* the result of a relation to predict what the curve will look like! That’s way more than what most CSS authors are comfortable with. Sure, cubic bezier values have the same problem, but at least designers are more familiar with them empirically from vector drawing programs, are already used in other parts of CSS, and there are non-academic tools to assist working with them.

Received on Wednesday, 5 August 2015 16:17:49 UTC

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