import pygame
import random
pygame.init()
#加载图片
pic=pygame.image.load('raining.jpg')
#获取图片的长宽
screen_width=pic.get_width()
screen_height=pic.get_height()
#根据图片大小来设置屏幕大小
screen=pygame.display.set_mode([screen_width,screen_height])
#设置彩虹雨的雨滴个数，颜色，位置，大小，落下的速度
numbers=50
colors=[0]*numbers
location_x=[0]*numbers
location_y=[0]*numbers
sizes=[0]*numbers
speed=[0]*numbers
#初始化彩虹雨滴
for i in range(numbers):
 colors[i]=(random.randint(0,255),random.randint(0,255),random.randint(0,255))
 location_x[i]=random.randint(0,screen_width)
 location_y[i]=-random.randint(0,screen_height)
 sizes[i]=random.randint(5,20)
 speed[i]=random.randint(1,5)

keep_going=True
#用Clock实现来控制动画的速度
timer=pygame.time.Clock()

while keep_going:
 for event in pygame.event.get(): #监听事件
 if event.type==pygame.QUIT:
  keep_going=False
 #把图片绘制到屏幕
 screen.blit(pic,(0,0))
 for i in range(numbers):
 pygame.draw.circle(screen,colors[i],(location_x[i],location_y[i]),sizes[i]) #让雨滴画在屏幕上
 location_y[i]=location_y[i]+speed[i]   #雨滴落下，y轴方向

 if location_y[i]>screen_height:    #如果雨滴落到看不见，即超出屏幕的高度
  location_y[i]-=screen_height   #重新设置雨滴的参数
  location_x[i]=random.randint(0,screen_width)
  speed[i] = random.randint(1, 5)
 timer.tick(100)# timer每秒钟滴答100次，因此帧率为100fps
 pygame.display.update() #刷新屏幕

pygame.quit()