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Re: [css-image] gradient midpoints

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Mon, 29 Sep 2014 09:40:44 -0700
Message-ID: <CAAWBYDC0zgiv8XsSWGHoUr5QThsFLGWMe-Bsysfwoi0cbqjFGg@mail.gmail.com>
To: Rik Cabanier <cabanier@gmail.com>
Cc: www-style list <www-style@w3.org>
On Sun, Sep 28, 2014 at 8:41 PM, Rik Cabanier <cabanier@gmail.com> wrote:
> All,
> I have a couple of question about the current wording of midpoints for CSS
> gradients.
>
> 1. The spec [1] contains 2 contradictory statements:
>
> Similarly, the color of a color stop can be omitted. The causes the color to
> be automatically computed to halfway between the two surrounding stops, so
> that the "midpoint" of a transition can be easily adjusted. If multiple
> stops in a row lack a color, they space themselves out equally in "color
> space", giving more control over the smoothness of the transition.
>
> and:
>
> There can only be at most one color interpolation hint between any two given
> normal color stops; using more than that makes the function invalid.
>
> I think the second statement is the correct one since exponential
> interpolation between midpoints is not defined.

Yup, I noticed that I still had contradictory stuff around when I was
trimming it for Images 3.  I'll fix.

> 2. The spec also doesn't require that a midpoint is not the first or last
> stop in a gradient.

Yes it does, per the grammar.

> 3. I think it's OK to assume that a midpoint that coincides with a regular
> stop, does nothing?

No, I'm pretty sure it has a (dramatic) effect on interpolation.  Why
would it do nothing?

> 4. It is now legal to write a color stop with no information at all.
> For instance: linear-gradient(white 0%,,black 100%) -> note the two commas.
> Is this OK?

That's not legal.  What part of the grammar makes you think that?

~TJ
Received on Monday, 29 September 2014 16:41:32 UTC

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