payhon贪吃蛇tkinter

### 使用 Python 和 Tkinter 实现贪吃蛇游戏

#### 加载所需库
为了创建基于 `Tkinter` 的贪吃蛇游戏，首先需要导入必要的模块。这通常包括 `tkinter` 本身以及用于处理时间延迟的 `time` 模块。

import tkinter as tk
from random import randint
import time

#### 初始化窗口和画布
设置主窗口大小并配置背景颜色；接着定义一个 Canvas 组件作为绘图区域，在其中绘制所有的游戏元素。

root = tk.Tk()
root.title("Snake Game with Tkinter")

canvas_width = 600
canvas_height = 400
canvas_bg_color = "black"

game_canvas = tk.Canvas(root, width=canvas_width, height=canvas_height, bg=canvas_bg_color)
game_canvas.pack()

#### 定义基本参数
设定网格尺寸、初始方向以及其他一些全局变量以便于后续逻辑操作。

grid_size = 20
directions = {"Up": (-1, 0), "Down": (1, 0), "Left": (0, -1), "Right": (0, 1)}
current_direction = directions["Right"]

snake_body = [(randint(5, canvas_height//grid_size-5)*grid_size,
               randint(5, canvas_width//grid_size-5)*grid_size)]
food_position = None
score = 0
speed_delay = 0.1

#### 食物生成函数
每当蛇吃到食物后都需要重新随机放置新的食物位置，并确保不会出现在当前蛇体上。

def place_food():
    global food_position
    
    while True:
        new_x = randint(0, (canvas_width // grid_size)-1) * grid_size
        new_y = randint(0, (canvas_height // grid_size)-1) * grid_size
        
        if (new_x, new_y) not in snake_body:
            break
            
    food_position = (new_x, new_y)
    
place_food()  # 初始时调用一次以生成第一个食物的位置

#### 移动蛇的方法
根据当前的方向更新蛇头的新坐标，并将其加入到身体列表前端。如果撞墙或碰到自己则结束游戏。

def move_snake():
    head_x, head_y = snake_body[0]

    delta_x, delta_y = current_direction
    next_head_pos = ((head_x + delta_x*grid_size)%canvas_width,
                     (head_y + delta_y*grid_size)%canvas_height)

    if next_head_pos in snake_body or \
       next_head_pos == tuple(map(lambda i,j:i-j,(next_head_pos),(delta_x*grid_size,delta_y*grid_size))):
        game_over()

    elif next_head_pos != food_position:
        snake_body.pop(-1)  # 如果没有吃到食物，则移除最后一节尾巴保持长度不变

    else:
        global score; score += 1
        place_food()      # 吃到了食物就要再放一个新的出来哦~

    snake_body.insert(0, next_head_pos)

#### 更新界面显示
每次移动完成后都要清除旧的画面重绘最新的状态，包括蛇的身体部分还有剩余的食物点位。

def draw_game():
    game_canvas.delete(tk.ALL)

    for segment in snake_body:
        game_canvas.create_rectangle(segment[0], segment[1],
                                     segment[0]+grid_size, segment[1]+grid_size,
                                     fill="green", outline="white")

    if food_position is not None:
        game_canvas.create_oval(food_position[0], food_position[1],
                                food_position[0]+grid_size, food_position[1]+grid_size,
                                fill="red", outline="")
        
    root.update_idletasks()
    root.after(int(speed_delay*1000), update_game_state)

#### 控制输入监听事件绑定
通过键盘按键改变前进方向，注意防止反向回转的情况发生。

def change_direction(event):
    key = event.keysym

    opposites = {v:k for k,v in directions.items()}
    opposite_dir = opposites.get(current_direction[::-1])

    if key in ["w","W"] and opposite_dir!="Up":
        set_new_direction(directions["Up"])
    elif key in ["a","A"] and opposite_dir!="Left":
        set_new_direction(directions["Left"])
    elif key in ["d","D"] and opposite_dir!="Right":
        set_new_direction(directions["Right"])
    elif key in ["s","S"] and opposite_dir!="Down":
        set_new_direction(directions["Down"])

def set_new_direction(new_dir):
    global current_direction
    current_direction = new_dir

#### 主循环定时器驱动
利用 `after()` 方法每隔一定毫秒数触发一次回调来进行帧刷新。

def update_game_state():
    try:
        move_snake()
        draw_game()
    except Exception as e:
        print(f"Game Over! Error occurred: {e}")
        exit()

root.bind("<KeyPress>", change_direction)
update_game_state()
root.mainloop()