// Mixes the current color with a white that has the same alpha.
public static Color Lightened(this Color _, double f)
{
var white = new Color(1, 1, 1, _.Alpha);
return(_.Mixed(white, f));
}
// Mixes the current color with a black that has the same alpha.
public static Color Darkened(this Color _, double f)
{
var black = new Color(0, 0, 0, _.Alpha);
return(_.Mixed(black, f));
}