/// <summary>
/// Convert a color using the HSL to RGB.
/// </summary>
/// <param name="alpha">The alpha component (0.0-1.0).</param>
/// <param name="hue">The Hue component (0.0 - 360.0).</param>
/// <param name="saturation">The saturation component (0.0 - 1.0).</param>
/// <param name="luminosity">The luminosity component (0.0 - 1.0).</param>
public static HtmlColor FromHsl(double alpha, double hue, double saturation, double luminosity)
{
if (alpha < 0.0 || alpha > 1.0)
{
throw new ArgumentOutOfRangeException(nameof(alpha), alpha, "Alpha should be comprised between 0.0 and 1.0");
}
if (hue < 0 || hue > 360)
{
throw new ArgumentOutOfRangeException(nameof(hue), hue, "Hue should be comprised between 0° and 360°");
}
if (saturation < 0 || saturation > 1)
{
throw new ArgumentOutOfRangeException(nameof(saturation), saturation, "Saturation should be comprised between 0.0 and 1.0");
}
if (luminosity < 0 || luminosity > 1)
{
throw new ArgumentOutOfRangeException(nameof(luminosity), luminosity, "Brightness should be comprised between 0.0 and 1.0");
}
if (0 == saturation)
{
return(HtmlColor.FromArgb(alpha, Convert.ToByte(luminosity * 255),
Convert.ToByte(luminosity * 255), Convert.ToByte(luminosity * 255)));
}
double fMax, fMid, fMin;
int iSextant;
if (0.5 < luminosity)
{
fMax = luminosity - (luminosity * saturation) + saturation;
fMin = luminosity + (luminosity * saturation) - saturation;
}
else
{
fMax = luminosity + (luminosity * saturation);
fMin = luminosity - (luminosity * saturation);
}
iSextant = (int)Math.Floor(hue / 60f);
if (300f <= hue)
{
hue -= 360f;
}
hue /= 60f;
hue -= 2f * (float)Math.Floor(((iSextant + 1f) % 6f) / 2f);
if (0 == iSextant % 2)
{
fMid = hue * (fMax - fMin) + fMin;
}
else
{
fMid = fMin - hue * (fMax - fMin);
}
byte iMax = Convert.ToByte(fMax * 255);
byte iMid = Convert.ToByte(fMid * 255);
byte iMin = Convert.ToByte(fMin * 255);
switch (iSextant)
{
case 1:
return(HtmlColor.FromArgb(alpha, iMid, iMax, iMin));
case 2:
return(HtmlColor.FromArgb(alpha, iMin, iMax, iMid));
case 3:
return(HtmlColor.FromArgb(alpha, iMin, iMid, iMax));
case 4:
return(HtmlColor.FromArgb(alpha, iMid, iMin, iMax));
case 5:
return(HtmlColor.FromArgb(alpha, iMax, iMin, iMid));
default:
return(HtmlColor.FromArgb(alpha, iMax, iMid, iMin));
}
}
