animatewarp无法识别？

Question

我得到了这本书：“用于十几岁的视觉c＃游戏编程”（作者：Jonathan s.Harbour）。 它看起来很旧，事实上这段代码不起作用：

     namespace RPG
{
public class Sprite
{
    public Enum AnimateDir
    {
        NONE = 0,
        FORWARD = 1,
        BACKWARD = -1
    }
    public Enum AnimateWrap
    {
        WRAP = 0,
        BOUNCE = 1
    }
    private Game p_game;
    private PointF p_position;
    private PointF p_velocity;
    private Size p_size;
    private Bitmap p_bitmap;
    private bool p_alive;
    private int p_columns;
    private int p_totalFrames;
    private int p_currentFrame;
    private AnimateDir p_animationDir;  //the error is here
    private AnimateWrap p_animationWrap;//and here
    private int p_lastTime;
    private int p_animationRate;

    public Sprite(ref Game game)
    {
  p_game = game;
  p_position = new PointF(0, 0);
  p_velocity = new PointF(0, 0);
  p_size = new Size(0, 0);
  p_bitmap = null;
  p_alive = true;
  p_columns = 1;
  p_totalFrames = 1;
  p_currentFrame = 0;
  p_animationDir = AnimateDir.FORWARD;
  p_animationWrap = AnimateWrap.WRAP;
  p_lastTime = 0;
  p_animationRate = 30;
}

}
}

代码继续（有关更多信息，数字图书为here 它说'WindowsFormApplication1.RPG.Sprite.AnimateDir'是'propriety'但是像'type'一样使用 同样的事情：“AnimateWrap”