求助

niconiconico

import pygame
import sys
pygame.init()
screencaption=pygame.display.set_caption('helloworld')
screen=pygame.display.set_mode([640,480])
screen.fill([255,255,255])
speed = [-2,1]
tu = pygame.image.load('long.jpg')
position = tu.get_rect()

while True:
    for event in pygame.event.get():
        if event.type==pygame.QUIT:
            sys.exit()
position = position.move(speed)
if position.left< 0 or position.right>width:
    tu = pygame.transform.flip(tu,True,False)
    speed[0] = -speed[0]
if position.top <0 or position.bottom>hight:
    speed[1]=-speed[1]
screen.fill(bg)
screen.blit(tu.position)
pygame.display.flip()
pygame.time.delay(10)
   



按照16.2编的，为什么显示不出图像，而且一开始是黑屏

ba21