/// <summary>
/// Determines which contrast guidelines have been met for two colors.
/// Based on the [contrast calculations recommended by W3] (https://www.w3.org/WAI/WCAG21/Understanding/contrast-enhanced.html).
/// </summary>
/// <param name="rgbColor"></param>
/// <returns></returns>
public ContrastScore MeetsContrastGuidelines(RgbColor rgbColor)
{
double contrastRatio = GetContrast(rgbColor);
return(new ContrastScore
{
AA = contrastRatio >= 4.5,
AALarge = contrastRatio >= 3,
AAA = contrastRatio >= 7,
AAALarge = contrastRatio >= 4.5,
});
}
/// <summary>
/// Returns an HslColor object from a string.
/// </summary>
/// <param name="color"></param>
/// <param name="rgbColor"></param>
/// <returns></returns>
public static bool TryParse(string color, out RgbColor rgbColor)
{
try
{
rgbColor = Parse(color);
return(true);
}
catch (Exception)
{
rgbColor = null;
return(false);
}
}
/// <summary>
/// Mixes the two provided colors together by calculating the average of each of the RGB components weighted to the first color by the provided weight.
/// </summary>
/// <param name="otherColor"></param>
/// <param name="weight"></param>
/// <returns></returns>
public RgbColor Mix(RgbColor otherColor, double weight)
{
RgbColor color1 = new RgbColor
{
Red = Red,
Green = Green,
Blue = Blue,
Alpha = Alpha.HasValue ? Alpha : 1
};
RgbColor color2 = new RgbColor
{
Red = otherColor.Red,
Green = otherColor.Green,
Blue = otherColor.Blue,
Alpha = otherColor.Alpha.HasValue ? otherColor.Alpha : 1
};
// The formular is copied from the original Sass implementation:
// http://sass-lang.com/documentation/Sass/Script/Functions.html#mix-instance_method
double alphaDelta = color1.Alpha.Value - color2.Alpha.Value;
double x = weight * 2 - 1;
double y = x * alphaDelta == -1 ? x : x + alphaDelta;
double z = 1 + x * alphaDelta;
double weight1 = (y / z + 1) / 2;
double weight2 = 1 - weight1;
RgbColor mixedColor = new RgbColor
{
Red = (int)Math.Floor(color1.Red * weight1 + color2.Red * weight2),
Green = (int)Math.Floor(color1.Green * weight1 + color2.Green * weight2),
Blue = (int)Math.Floor(color1.Blue * weight1 + color2.Blue * weight2),
Alpha = color1.Alpha + (color2.Alpha - color1.Alpha) * weight
};
return(mixedColor);
}
/// <summary>
/// Returns an HslColor object from a string.
/// </summary>
/// <param name="color"></param>
/// <returns></returns>
public static RgbColor Parse(string color)
{
string hexRegex = "^#[a-fA-F0-9]{6}$";
string hexRgbaRegex = "^#[a-fA-F0-9]{8}$";
string reducedHexRegex = "^#[a-fA-F0-9]{3}$";
string reducedRgbaHexRegex = "^#[a-fA-F0-9]{4}$";
string rgbRegex = @"rgb\(\s*(\d{1,3})\s*,\s*(\d{1,3})\s*,\s*(\d{1,3})\s*\)$";
string rgbaRegex = @"^rgba\(\s*(\d{1,3})\s*,\s*(\d{1,3})\s*,\s*(\d{1,3})\s*,\s*([-+]?[0-9]*[.]?[0-9]+)\s*\)$";
string hslRegex = @"^hsl\(\s*(\d{0,3}[.]?[0-9]+)\s*,\s*(\d{1,3})%\s*,\s*(\d{1,3})%\s*\)$";
string hslaRegex = @"^hsla\(\s*(\d{0,3}[.]?[0-9]+)\s*,\s*(\d{1,3})%\s*,\s*(\d{1,3})%\s*,\s*([-+]?[0-9]*[.]?[0-9]+)\s*\)$";
Conversion conversion = new Conversion();
string normalizedColor = conversion.NameToHex(color);
if (Regex.IsMatch(normalizedColor, hexRegex))
{
return(new RgbColor
{
Red = int.Parse($"{normalizedColor[1]}{normalizedColor[2]}", System.Globalization.NumberStyles.HexNumber),
Green = int.Parse($"{normalizedColor[3]}{normalizedColor[4]}", System.Globalization.NumberStyles.HexNumber),
Blue = int.Parse($"{normalizedColor[5]}{normalizedColor[6]}", System.Globalization.NumberStyles.HexNumber)
});
}
if (Regex.IsMatch(normalizedColor, hexRgbaRegex))
{
double alpha = Math.Round(
((double)int.Parse($"{normalizedColor[7]}{normalizedColor[8]}", System.Globalization.NumberStyles.HexNumber) / 255)
, 2);
return(new RgbColor
{
Red = int.Parse($"{normalizedColor[1]}{normalizedColor[2]}", System.Globalization.NumberStyles.HexNumber),
Green = int.Parse($"{normalizedColor[3]}{normalizedColor[4]}", System.Globalization.NumberStyles.HexNumber),
Blue = int.Parse($"{normalizedColor[5]}{normalizedColor[6]}", System.Globalization.NumberStyles.HexNumber),
Alpha = alpha
});
}
if (Regex.IsMatch(normalizedColor, reducedHexRegex))
{
return(new RgbColor
{
Red = int.Parse($"{normalizedColor[1]}{normalizedColor[1]}", System.Globalization.NumberStyles.HexNumber),
Green = int.Parse($"{normalizedColor[2]}{normalizedColor[2]}", System.Globalization.NumberStyles.HexNumber),
Blue = int.Parse($"{normalizedColor[3]}{normalizedColor[3]}", System.Globalization.NumberStyles.HexNumber)
});
}
if (Regex.IsMatch(normalizedColor, reducedRgbaHexRegex))
{
double alpha = Math.Round(
((double)int.Parse($"{normalizedColor[4]}{normalizedColor[4]}", System.Globalization.NumberStyles.HexNumber) / 255)
, 2);
return(new RgbColor
{
Red = int.Parse($"{normalizedColor[1]}{normalizedColor[1]}", System.Globalization.NumberStyles.HexNumber),
Green = int.Parse($"{normalizedColor[2]}{normalizedColor[2]}", System.Globalization.NumberStyles.HexNumber),
Blue = int.Parse($"{normalizedColor[3]}{normalizedColor[3]}", System.Globalization.NumberStyles.HexNumber),
Alpha = alpha
});
}
MatchCollection rgbMatched = new Regex(rgbRegex, RegexOptions.IgnoreCase).Matches(normalizedColor);
if (rgbMatched.Count > 0)
{
return(new RgbColor
{
Red = int.Parse(rgbMatched[0].Groups[1].Value),
Green = int.Parse(rgbMatched[0].Groups[2].Value),
Blue = int.Parse(rgbMatched[0].Groups[3].Value)
});
}
MatchCollection rgbaMatched = new Regex(rgbaRegex, RegexOptions.IgnoreCase).Matches(normalizedColor);
if (rgbaMatched.Count > 0)
{
return(new RgbColor
{
Red = int.Parse(rgbaMatched[0].Groups[1].Value),
Green = int.Parse(rgbaMatched[0].Groups[2].Value),
Blue = int.Parse(rgbaMatched[0].Groups[3].Value),
Alpha = double.Parse(rgbaMatched[0].Groups[4].Value)
});
}
MatchCollection hslMatched = new Regex(hslRegex, RegexOptions.IgnoreCase).Matches(normalizedColor);
if (hslMatched.Count > 0)
{
double hue = double.Parse(hslMatched[0].Groups[1].Value);
double saturation = double.Parse(hslMatched[0].Groups[2].Value) / 100;
double lightness = double.Parse(hslMatched[0].Groups[3].Value) / 100;
HslColor hsl = new HslColor {
Hue = hue, Saturation = saturation, Lightness = lightness
};
return(hsl.ToRgb());
}
MatchCollection hslaMatched = new Regex(hslaRegex, RegexOptions.IgnoreCase).Matches(normalizedColor);
if (hslaMatched.Count > 0)
{
double hue = double.Parse(hslaMatched[0].Groups[1].Value);
double saturation = double.Parse(hslaMatched[0].Groups[2].Value) / 100;
double lightness = double.Parse(hslaMatched[0].Groups[3].Value) / 100;
HslColor hsl = new HslColor {
Hue = hue, Saturation = saturation, Lightness = lightness
};
RgbColor rgba = hsl.ToRgb();
rgba.Alpha = double.Parse(hslaMatched[0].Groups[4].Value);
return(rgba);
}
throw PolishedException.GetPolishedException(5);
}
/// <summary>
/// Converts the HslColor object to an RgbColor object.
/// </summary>
/// <returns></returns>
public RgbColor ToRgb()
{
return(RgbColor.Parse(ToString()));
}
/// <summary>
/// Returns an HslColor object from a string.
/// </summary>
/// <param name="color"></param>
/// <returns></returns>
public static HslColor Parse(string color)
{
return(RgbColor.Parse(color).ToHsl());
}
