Python程序：用Pygame Zero实现一个四处碰壁后可自动弹开的小球

import pgzrun
from pgzhelper import *   # pygame zero helper导入，否则无法使用放大缩小acotr的大小的函数

WIDTH=500
HEIGHT=500

Ball=Actor('ball',(WIDTH/2, HEIGHT/2))
Ball.scale=0.05
Ball.dx=1
Ball.dy=1

def draw():
    screen.clear()
    Ball.draw()

def update():
    global Ball

    Ball.x += Ball.dx
    Ball.y += Ball.dy

    if Ball.right >= WIDTH or Ball.left <= 0:
        Ball.dx = -Ball.dx
    if Ball.bottom >= HEIGHT or Ball.top <= 0:
        Ball.dy = -Ball.dy

pgzrun.go()