/// <summary>
/// Creates a color from rgba color string.
/// </summary>
/// <returns></returns>
private void ColorFromRgb()
{
var cssFunc = new CssFunction(Value);
var args = cssFunc.Arguments;
var a = new CssDimension("255").Number;
var r = new CssDimension(args[0]).Number;
var g = new CssDimension(args[1]).Number;
var b = new CssDimension(args[2]).Number;
if (args.Count == 4)
{
a = new CssDimension(args[3]).Number;
}
Color = Color.FromArgb((int)a, (int)r, (int)g, (int)b);
}
private CssColorFormat ColorFormat()
{
if (Value.IndexOf('(') > 0)
{
// Uses a functional color format.
var function = new CssFunction(Value);
var functionName = function.FunctionName;
switch (functionName)
{
case "hsl":
return(CssColorFormat.HSL);
case "hsla":
return(CssColorFormat.HSLA);
case "rgb":
return(CssColorFormat.RGB);
case "rgba":
return(CssColorFormat.RGBA);
default:
return(CssColorFormat.Unknown);
}
}
else if (Value.StartsWith("#", StringComparison.Ordinal))
{
// Is a hex format.
return(CssColorFormat.Hexadecimal);
}
else if (String.Equals("currentColor", Value, StringComparison.Ordinal))
{
return(CssColorFormat.CurrentColor);
}
else if (String.Equals("transparent", Value, StringComparison.Ordinal))
{
return(CssColorFormat.Transparent);
}
else
{
// It's most likely a keyword.
return(CssColorFormat.BasicColorKeyword);
}
}
#pragma warning disable CS1658 // Warning is overriding an error
#pragma warning disable CS1584 // XML comment has syntactically incorrect cref attribute
/// <summary>
/// Assigns Color from value interperted as an hsl function.
/// </summary>
/// <returns></returns>
/// <seealso cref="https://www.w3.org/TR/css-color-3/#hsl-color"></seealso>
#pragma warning restore CS1584 // XML comment has syntactically incorrect cref attribute
#pragma warning restore CS1658 // Warning is overriding an error
private void ColorFromHsl()
{
var function = new CssFunction(Value);
var functionArgs = function.Arguments;
//HOW TO RETURN hsl.to.rgb(h, s, l):
// SELECT:
// IF l <= 0.5: PUT l*(s + 1) IN m2
// ELSE: PUT l+s - l * s IN m2
// PUT l*2 - m2 IN m1
// PUT hue.to.rgb(m1, m2, h + 1 / 3) IN r
// PUT hue.to.rgb(m1, m2, h) IN g
// PUT hue.to.rgb(m1, m2, h - 1 / 3) IN b
// RETURN(r, g, b)
//HOW TO RETURN hue.to.rgb(m1, m2, h):
// IF h<0: PUT h+1 IN h
// IF h> 1: PUT h-1 IN h
// IF h*6 < 1: RETURN m1+(m2 - m1) * h * 6
// IF h*2 < 1: RETURN m2
// IF h*3 < 2: RETURN m1+(m2 - m1) * (2 / 3 - h) * 6
// RETURN m1
double h = 0,
s = 0,
l = 0;
double m1 = 0,
m2 = 0;
int r = 0,
g = 0,
b = 0,
a = 255; // Default to full transparency.
var hCss = new CssDimension(functionArgs[0]);
var sCss = new CssDimension(functionArgs[1]);
var lCss = new CssDimension(functionArgs[2]);
switch (hCss.UnitOfMeasurement)
{
case CssUnit.None:
case CssUnit.Percent:
h = Normalize(value: hCss.Number,
actualMin: 0,
actualMax: 100);
break;
case CssUnit.Degrees:
h = Normalize(
value: hCss.Number,
actualMin: 0,
actualMax: 360);
break;
case CssUnit.Radians:
h = Normalize(
value: hCss.Number,
actualMin: 0,
actualMax: Math.PI * 2);
break;
case CssUnit.Turn:
h = Normalize(
value: hCss.Number,
actualMin: 0,
actualMax: 1);
break;
case CssUnit.Gradians:
var asRads = (hCss.Number * (180 / 200)) / .9;
h = Normalize(
value: hCss.Number,
actualMin: 0,
actualMax: Math.PI * 2);
break;
default:
throw new NotImplementedException(Enum.GetName(
typeof(CssUnit),
hCss.UnitOfMeasurement));
}
// Verify the 's' and 'l' units are in percent.
if (sCss.UnitOfMeasurement != CssUnit.Percent ||
lCss.UnitOfMeasurement != CssUnit.Percent)
{
throw new Exception();
}
// Assign 's' and 'l'.
s = Normalize(
value: sCss.Number,
actualMin: 0,
actualMax: 100,
desiredMin: 0,
desiredMax: 1);
l = Normalize(
value: lCss.Number,
actualMin: 0,
actualMax: 100,
desiredMin: 0,
desiredMax: 1);
// Parse alpha if available.
if (functionArgs.Count == 4)
{
var aCss = new CssDimension(functionArgs[3]);
if (aCss.UnitOfMeasurement == CssUnit.Percent)
{
a = (int)Normalize(value: aCss.Number,
actualMin: 0,
actualMax: 100,
desiredMin: 0,
desiredMax: 255);
}
else if (aCss.UnitOfMeasurement == CssUnit.None)
{
a = (int)Normalize(value: aCss.Number,
actualMin: 0,
actualMax: 1,
desiredMin: 0,
desiredMax: 255);
}
}
// Local function equivilent to the hue.to.rgb function.
double hueToRgb(double _h)
{
if (_h < 0)
{
_h = _h + 1d;
}
if (_h > 1d)
{
_h = _h - 1d;
}
if (_h * 6d < 1d)
{
return(m1 + (m2 - m1) * _h * 6d);
}
else if (_h * 2d < 1d)
{
return(m2);
}
else if (_h * 3d < 2d)
{
return(m1 + (m2 - m1) * (2d / 3d - _h) * 6);
}
else
{
return(m1);
}
}
if (l <= 0.5)
{
m2 = l * (s + 1d);
}
else
{
m2 = l + s - 1d * s;
}
m1 = l * 2 - m2;
r = (int)hueToRgb(h + (1d / 3d));
g = (int)hueToRgb(h);
b = (int)hueToRgb(h - (1d / 3d));
// Re-normalize r, g, and b.
r *= 255;
g *= 255;
b *= 255;
Color = Color.FromArgb(a, r, g, b);
}
