如何在重新缩放pygame窗口后保留旧屏幕上的内容？

import pygame

# 初始化pygame
pygame.init()

# 设置窗口的初始大小
initial_size = (800, 600)

# 创建窗口
screen = pygame.display.set_mode(initial_size)
pygame.display.set_caption("Pygame Window Rescaling")

# 绘制初始内容
screen.fill((255, 255, 255))
pygame.draw.rect(screen, (255, 0, 0), pygame.Rect(200, 150, 400, 300))
pygame.display.flip()

# 获取旧屏幕内容
old_screen = screen.copy()

# 重新缩放窗口
new_size = (400, 300)
screen = pygame.display.set_mode(new_size)
pygame.display.set_caption("Rescaled Pygame Window")

# 绘制旧屏幕内容到新窗口
screen.blit(old_screen, (0, 0))
pygame.display.flip()

# 游戏循环
running = True
while running:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False

# 退出pygame
pygame.quit()