/// <summary>
/// retrieve rainbow rgb color from a double value between [0,1]
/// </summary>
public static IRgb FromRainbow(this double factor)
{
/*
* test : http://serennu.com/colour/hsltorgb.php
* RGB: 218 165 32
* HSL: 43° 74% 49%
* Hex: #DAA520
*/
/*
* RAINBOW COLORS
*
* red hsl(0,100%,50%)
* orange hsl(30,100%,50%)
* yellow hsl(60,100%,50%)
* green hsl(120,100%,50%)
* cyan hsl(180,100%,50%)
* blue hsl(240,100%,50%)
* purple hsl(270,100%,50%)
* magenta hsl(300,100%,50%)
*/
var hsl = new Hsl();
// rainbow hue on range [0,240]
hsl.H = (1.0 - factor) * 240;
// 100% saturation
hsl.S = 100;
// 50% luminance
hsl.L = 50;
return(hsl.ToRgb());
}
internal static Color ToColor(this Hsl hsl)
{
Func <double, int> round = x => (int)Math.Round(x);
var rgb = hsl.ToRgb();
return(Color.FromArgb(round(rgb.R), round(rgb.G), round(rgb.B)));
}