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Re: Talk on radial gradients

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Mon, 24 Aug 2009 09:03:51 -0500
Message-ID: <dd0fbad0908240703p2d2c3618i5db288c7ce739304@mail.gmail.com>
To: François REMY <fremycompany_pub@yahoo.fr>
Cc: www-style list <www-style@w3.org>
On Mon, Aug 24, 2009 at 4:55 AM, François REMY<fremycompany_pub@yahoo.fr> wrote:
> I don't think a starting radius is useful. We could use a color stop.

I agree, but that does make it slightly more difficult to use % in an
easy way.  We'll see if it becomes significant; for now I'm keeping it

>> Second, I don't think an ending circle is necessary *at all*, with a
>> point or radius.  As I mentioned above, in every case of a radial
>> gradient that got passed to me in a design document, it was based
>> directly on the box itself.  Thus the box itself should provide the
>> ending circle.  There are several ways to do this, and I think they're
>> all valid - frex, you could want to end with a circle as wide as the
>> box, or as tall as the box, or as large as the smaller or larger
>> dimension, or large enough to fully contain the box (the circle
>> circumscribes the box).  All of these seem to be valid and reasonable,
>> and I would expect that they'd see real use in decent numbers.
> I think it can be. A radial gradient is specified by two things : * a center
> * an ending circle
> ===> a point of the ending circle
> ===> the radius of the ending circle

Agreed, but what I was saying is that in the common cases it's not
necessary to specify an ending-circle *explicitly*.  There are a
handful of reasonable values in common use based on the box.  If you
need something smaller you can probably use color-stops to deal with
it, or else just create a static gradient image.

> We could then change the syntax to add possibly a center and two radius
> It would be like:
>     radial-gradient(top left, 100%, 100%, ...)
> This would be a perfect ellipse centered top left.

Nod, I'm just trying to avoid explicitly specifying something like
that.  For one thing, it makes it impossible to specify flexible
circular gradients - the only way to make the gradient flex with the
box is with percentages, and then there's no way to tie the two values
together.  Four of my <shape> keywords deal with circular gradients.
For another thing, it makes it difficult/impossible to specify a
gradient which exactly surrounds the entire box (my "outer" value for

Basically, explicitly specifying the outer circle is only useful for
(a) static-sized gradients, which can just be done in any common image
editor, and (b) "inner" gradients.  It really robs you of a lot of
control while making you *feel* like you have more options.

Received on Monday, 24 August 2009 14:04:54 UTC

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