/// <summary>
/// Initializes a new instance of the <see cref="RGBA"/> structure.
/// </summary>
/// <param name="color">An <see cref="RGB"/> color.</param>
/// <param name="alpha">The alpha channel component.</param>
public RGBA(RGB color, double alpha) : this(color.Red, color.Green, color.Blue, alpha)
{
}
/// <summary>
/// Gets the luminance of the specified color.
/// </summary>
/// <param name="color">The color.</param>
/// <returns>The luminance value of the color.</returns>
public static double Luminance(this RGB color)
{
return(Luminance(color.Red, color.Green, color.Blue));
}
/// <summary>
/// Initializes a new instance of the <see cref="RGBA"/> structure.
/// </summary>
/// <param name="color">An <see cref="RGB"/> color.</param>
public RGBA(RGB color) : this(color.Red, color.Green, color.Blue, 1)
{
}
/// <summary>
/// Gets the best foreground color given the specified background color.
/// </summary>
/// <param name="color">The background color.</param>
/// <returns>The best <see cref="RGB"/> foreground color.</returns>
public static RGB GetBestForegroundColor(this RGB color)
{
return(color.Luminance() > rgbThreshold ? RGB.Black : RGB.White);
}