c# 小游戏代码

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Collections;

namespace WindowsApplication1
{
     public partial class Form1 : Form
     {
         public Form1()
         {
             InitializeComponent();
         }
         private bool i;//开关
         snake a_snake = new snake(5);//实例化个长度为5的蛇
         food afood = new food();//实例化一个食物
         private void pictureBox1_Paint(object sender, PaintEventArgs e)
         {
             Graphics g = e.Graphics;
             if (i)//点击了开始button
             {
                 a_snake.drawsnake(g);//画出蛇
                 afood.drawfood(g);//画出来食物
             }
             if (a_snake.deadsnake())//如果蛇死亡事件为真
             {

                 timer1.Enabled = false;//timer控件停止
                 if (DialogResult.Yes ==
                     MessageBox.Show("GAME OVER", "是否重新开始?", MessageBoxButtons.YesNo))
                 //messagebox消息
                 {
                     //点击确定后重新开始游戏
                     button1.Enabled = true;
                     a_snake = new snake(5);//初始化蛇
                     afood = new food();//初始化食物
                     i = false;//开关为假
                     g.Clear(pictureBox1.BackColor);//清理picturebox
                 }
                 else
                     Application.Exit();//关闭程序               
             }
         }
         private void button1_Click(object sender, EventArgs e)
         {
             i = true; //开关为真          
             afood.F_point = afood.getpoint();//产生一个食物的随机坐标
             pictureBox1.Refresh();//刷新picturebox
             timer1.Enabled = true;//开启timer控件
             timer1.Interval = 100; //时间间隔为0.1秒  
             button1.Enabled = false;
         }
         private void timer1_Tick(object sender, EventArgs e)
         {
             pictureBox1.Refresh();//刷新picturebox
             a_snake.extendsnake();//蛇伸长一节
             if (a_snake.headpoint == afood.F_point)