private static HslType HexToHsl(this string hexIn)
{
/*
* the source text is taken from here (with minor modifications):
* https://css-tricks.com/converting-color-spaces-in-javascript/
*/
// Convert hex to RGB first. Ignore opacity
RgbType rgb = hexIn.HexToRgb(1);
// Then to HSL
rgb.ToHsl();
var cmin = rgb.Min();
var cmax = rgb.Max();
var delta = cmax - cmin;
var hls = new HslType
{
Hue = ComputeH(rgb, cmax, delta),
Lightness = (cmax + cmin) / 2
};
hls.Saturation = delta == 0 ? 0 : delta / (1 - Math.Abs(2 * hls.Lightness - 1));
hls.Saturation = Convert.ToDouble(String.Format("{0:0.0}", hls.Saturation * 100));
hls.Lightness = Convert.ToDouble(String.Format("{0:0.0}", hls.Lightness * 100));
hls.Round();
return(hls);
}
public HslType(HslType offset)
{
if (offset == null)
{
throw new ArgumentNullException(nameof(offset));
}
Hue = offset.Hue;
Saturation = offset.Saturation;
Lightness = offset.Lightness;
}
public static HslType ColorShiftHsl(this string main, HslType offset)
{
if (main == null)
{
throw new ArgumentNullException(nameof(main));
}
if (offset == null)
{
throw new ArgumentNullException(nameof(offset));
}
var offsetCopy = new HslType(offset);
HslType color = main.HexToHsl();
color.Hue = NormalizeValue(color.Hue + offsetCopy.Hue, minValue: 0, maxValue: 360);
color.Saturation = NormalizeValue(color.Saturation + offsetCopy.Saturation);
color.Lightness = NormalizeValue(color.Lightness + offsetCopy.Lightness);
return(color);
}
public static (string, string) GetGradientColor(this string color)
{
if (color == null)
{
throw new ArgumentNullException(nameof(color));
}
HslType first = color.HexToHsl();
HslType second = color.HexToHsl();
// hue circle degrees approximation
bool isRed = (first.Hue >= 0 && first.Hue < 45) || (first.Hue >= 285);
bool isYellow = first.Hue >= 45 && first.Hue < 85;
bool isGreen = first.Hue >= 85 && first.Hue < 165;
bool isBlue = first.Hue >= 165 && first.Hue < 285;
bool isUndersaturated = first.Saturation < 30; // i.e. too pale, gray-ish, monotone
if (isRed)
{
first.Hue += 11;
first.Saturation += 27;
first.Lightness += 8;
}
else if (isYellow)
{
first.Hue += 3;
first.Lightness += 9;
second.Hue -= 2;
}
else if (isGreen)
{
first.Hue += 13;
first.Saturation -= 5;
first.Lightness += 7;
second.Hue -= 3;
second.Saturation -= 1;
second.Lightness -= 6;
}
else if (isBlue)
{
first.Hue -= 15;
first.Saturation += 3;
first.Lightness += 2;
}
if (isUndersaturated)
{
first.Lightness += 6;
second.Lightness -= 2;
}
// restrictions and validations
if (first.Hue < 0)
{
first.Hue += 360;
}
if (first.Hue > 0)
{
Math.Round(first.Hue = first.Hue % 360);
}
if (second.Hue < 0)
{
second.Hue += 360;
}
if (second.Hue > 0)
{
Math.Round(second.Hue = second.Hue % 360);
}
first.Saturation = first.Saturation > 0 ? first.Saturation : 0;
first.Saturation = first.Saturation < 100 ? first.Saturation : 100;
second.Saturation = second.Saturation > 0 ? second.Saturation : 0;
second.Saturation = second.Saturation < 100 ? second.Saturation : 100;
first.Lightness = first.Lightness > 0 ? first.Lightness : 0;
first.Lightness = first.Lightness < 100 ? first.Lightness : 100;
second.Lightness = second.Lightness > 0 ? second.Lightness : 0;
second.Lightness = second.Lightness < 100 ? second.Lightness : 100;
return(first.ToString(), second.ToString());
}