public ExtendOption(bool extend, GravityOption option = null)
        {
            Extend        = extend;
            GravityOption = option;

            if (option != null && option.Type == GravityTypes.Smart)
            {
                throw new ArgumentException(nameof(option));
            }
        }
 public CropOption(float width, float height, GravityOption option = null)
 {
     Width         = width;
     Height        = height;
     GravityOption = option;
 }