在屏幕上随机画点

#_*_coding:utf-8 _*_
from time import sleep

import pygame
from pygame.locals import  *
from sys import exit
from random import randint

pygame.init()
screen=pygame.display.set_mode((640,480),0,32)
while True:
    for event in pygame.event.get():
        if event.type==QUIT:
            exit()
    rand_col=(randint(0,255),randint(0,255),randint(0,255))
    #screen.lock()
    for _ in xrange(100):
        rand_pos=(randint(0,639),randint(0,479))
        screen.set_at(rand_pos,rand_col)
    #screen.unlock()
    #sleep(1)
    pygame.display.update()