fromColor

pub fn fromColor(c: Color) HSLuv {
        var ret: HSLuv = undefined;
        hsluv.rgb2hsluv(
            @as(f32, c.r) / 255.0,
            @as(f32, c.g) / 255.0,
            @as(f32, c.b) / 255.0,
            &ret.h,
            &ret.s,
            &ret.l,
        );
        ret.a = @as(f32, c.a) * 100.0 / 255.0;
        return ret;
    }