Re: [svg2] radialGradient @fr constraints

On Wed, Aug 29, 2012 at 1:32 AM, Erik Dahlstrom <ed@opera.com> wrote:

> Some issues regarding the added 'fr' attribute on radialGradient:
>
> a) Should 'fr' be allowed to be negative? (this is disallowed in
> <canvas>). What should happen if it is?
>

yes, that should not be allowed.


> b) Should we still keep the constraint[1] to move the focal point inside
> the other circle? <canvas> doesn't do this. What the spec currently defines
> means some kinds of conical gradients aren't possible to do with
> <radialGradient>.
>

No. let's remove it.


> c) Related to b): the case where the focal point is outside the other
> circle, but the focal radius makes the two circles intersect, how should
> that be handled?
>

The gradient will render as a cone.
Repeat/reflect might display a bit strange, but that's probably OK


>
> Proposal:
> a) disallow negative values for 'fr', and let these cases fallback to the
> lacuna value '0%'.
> b) remove the constraint and handle it the same as in <canvas>, noting
> that this may break some existing content. If we do this way it doesn't
> matter how the two circles are positioned relative to one another, so it
> addresses c) as well.
>

agreed


>
>
> [1] https://svgwg.org/svg2-draft/**pservers.html#**RadialGradientNotes<https://svgwg.org/svg2-draft/pservers.html#RadialGradientNotes>
> --
> Erik Dahlstrom, Core Technology Developer, Opera Software
> Co-Chair, W3C SVG Working Group
> Personal blog: http://my.opera.com/macdev_ed
>
>