如何截取整个显示pygame的屏幕截图

import pygame
import sys

pygame.init()
screen = pygame.display.set_mode((800, 600))

while True:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            pygame.quit()
            sys.exit()

pygame.display.flip()

pygame.image.save(screen, "screenshot.png")

import pygame
import sys

pygame.init()
screen = pygame.display.set_mode((800, 600))

while True:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            pygame.quit()
            sys.exit()

    # 渲染游戏界面
    # ...

    pygame.display.flip()

    # 截取屏幕截图
    pygame.image.save(screen, "screenshot.png")