篮球自动弹跳

#-*-codings:utf-8 -*-
import sys
import pygame

pygame.init()
size = width, height = 640, 480
screen = pygame.display.set_mode(size)
color = (0,0,0)

ball = pygame.image.load("ball.png")
ballrect = ball.get_rect()
speed = [5,5]
clock = pygame.time.Clock()
# 执行死循环，确保窗口一直显示
while True:
    clock.tick(60)
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            pygame.quit()
            sys.exit()
    ballrect = ballrect.move(speed)
#碰到左右边缘
    if ballrect.left < 0 or ballrect.right>width:
        speed[0] = -speed[0]
#碰到上下边缘
    if ballrect.top <0 or ballrect.bottom  >height:
        speed[1] = -speed[1]

    screen.fill(color)
    screen.blit(ball,ballrect)
    pygame.display.flip()