Re: [css-image] gradient midpoints

On Mon, Sep 29, 2014 at 9:40 AM, Tab Atkins Jr. <jackalmage@gmail.com>
wrote:

> 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.
>

OK. I was looking at the prose. Maybe you can clarify it there?


> > 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?


Yes, is that dramatic effect desirable?
Given 3 colorstops red, green and blue and a midpoint that coincides with
green, the gradient will be 2 squares red and blue.


> > 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?
>

Can you clarify that in the prose?