在pygame中切换菜单

import pygame
from pygame.locals import *

pygame.init()
screen = pygame.display.set_mode((width, height))
pygame.display.set_caption("游戏标题")

class Menu:
    def __init__(self, items):
        self.items = items

    def display_menu(self):
        # 绘制菜单界面的代码

    def run_menu(self):
        # 处理菜单事件的代码

def display_menu(self):
    # 清空屏幕
    screen.fill((0, 0, 0))

    # 绘制菜单项
    for index, item in enumerate(self.items):
        # 绘制菜单项的代码

    # 刷新屏幕
    pygame.display.flip()

def run_menu(self):
    while True:
        for event in pygame.event.get():
            if event.type == QUIT:
                pygame.quit()
                sys.exit()
            elif event.type == KEYDOWN:
                if event.key == K_UP:
                    # 处理向上键的代码
                elif event.key == K_DOWN:
                    # 处理向下键的代码
                elif event.key == K_RETURN:
                    # 处理回车键的代码

menu_items = ['开始游戏', '选项', '退出']
menu = Menu(menu_items)

while True:
    # 游戏主循环的代码

    # 判断是否需要切换菜单
    if need_to_switch_menu:
        menu.run_menu()