public static DoubleColor Lighter(
this DoubleColor c,
double coff = 0.25
)
{
AHSL hsl = ColorExt.ToAHSL(c);
hsl.Luminance = MathEx.Lerp(hsl.Luminance, 1, coff);
return(ColorExt.Double(hsl));
}
public static DoubleColor Double(
this AHSL hsl
)
{
double h = hsl.HueDegree;
double s = hsl.Saturation;
double l = hsl.Luminance;
double a = hsl.Alpha;
DoubleColor ret;
if (s == 0)
{
// achromatic color (gray scale)
ret = new DoubleColor(a * 255.0, l * 255.0, l * 255.0, l * 255.0);
}
else
{
double q = (l < 0.5) ? (l * (1.0 + s)) : (l + s - (l * s));
double p = (2.0 * l) - q;
double Hk = h / 360.0;
double[] T = new double[3];
T[0] = Hk + (1.0 / 3.0); // Tr
T[1] = Hk; // Tb
T[2] = Hk - (1.0 / 3.0); // Tg
for (int i = 0; i < 3; i++)
{
if (T[i] < 0)
{
T[i] += 1.0;
}
if (T[i] > 1)
{
T[i] -= 1.0;
}
if ((T[i] * 6) < 1)
{
T[i] = p + ((q - p) * 6.0 * T[i]);
}
else if ((T[i] * 2.0) < 1) // (1.0 / 6.0) <= T[i] && T[i] < 0.5
{
T[i] = q;
}
else if ((T[i] * 3.0) < 2) // 0.5 <= T[i] && T[i] < (2.0/3.0)
{
T[i] = p + (q - p) * ((2.0 / 3.0) - T[i]) * 6.0;
}
else
{
T[i] = p;
}
}
ret = new DoubleColor(a * 255.0, T[0] * 255.0, T[1] * 255.0, T[2] * 255.0);
}
//
// this will preserve hue for gray colors, and saturation for black
//
ret.HueDegree = h;
ret.Saturation = s;
return(ret);
}