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Re: Comments on gradient syntax proposal

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Tue, 27 Oct 2009 12:15:55 -0500
Message-ID: <dd0fbad0910271015i5bc1c40al57c65b330a775193@mail.gmail.com>
To: "L. David Baron" <dbaron@dbaron.org>
Cc: www-style@w3.org
On Tue, Oct 27, 2009 at 11:24 AM, L. David Baron <dbaron@dbaron.org> wrote:
> Here are a few minor comments on the current version gradient syntax
> proposal at http://www.xanthir.com/:4bhipd .  (It might be good to
> have a dated version archived at some point, though.)  I noticed
> these issues while reviewing the patch to implement this proposal in
> Mozilla.
>
> # if relevant, the angle is normalized to within the range
> # [0,360deg)
> (occurs once for linear gradients and once for radial)
>
> Normalizing angles is a bad idea for animation.  It makes it
> impossible to animate angles through a sweep that includes pointing
> left.  I think you should just remove mention of normalization.

That makes it more difficult to specify the starting-corner for
gradients that have an <angle> argument.  Would it be sufficient to
move the talk of normalization to that section of the spec, avoiding
any possibility that an implementor accidentally normalizes early?

> # Between two color-stops, the colors are interpolated as SVG
> # gradients.
>
> The spec ought to say explicitly whether this means that the
> 'color-interpolation' property applies.  See
> http://www.w3.org/TR/SVG11/painting.html#ColorInterpolationProperty

Should it apply?  I'm not sure.  I don't have a good grasp of SVG.

> In the description of radial gradients:
>
> # The image is constructed by creating an infinite canvas and
> # painting it with concentric copies of the ending-shape, with the
> # color of the painted shape being the color of the gradient-line
> # where the two intersect.
>
> Saying that ellipses are concentric doesn't define what they are.  I
> think what you want to say is that they are concentric *and* the
> ratio of their major axis to minor axis is constant.  (You could,
> for example, have concentric ellipses that are confocal, but I
> really don't think that's what's desired here.)

I have added the word "similar" to that sentence, which should address this.

> # If <shape> is ellipse and <size> is closest-side, the
> # gradient-shape is an ellipse sized so that it exactly meets the
> # two sides of the box closest to its center.
>
> This needs to say that it's the closest horizontal side and the
> closest vertical side, since the two closest sides might be
> parallel.

I've made this change to the areas I could spot that needed it.

~TJ
Received on Tuesday, 27 October 2009 17:16:46 GMT

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