python pygame实现简单的绘图程序

重点理解Pygame创建窗口和监听键盘的函数，以及参数

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


pygame.init()
SCREEN_DEFAULT_SIZE = (500, 500)
SCREEN_DEFAULT_COLOR = (255, 255 ,255)
screen = pygame.display.set_mode(SCREEN_DEFAULT_SIZE, 0, 32)
screen.fill(SCREEN_DEFAULT_COLOR)

while True:
    for event in pygame.event.get():
        if event.type ==  QUIT:
            exit()
        elif event.type == KEYDOWN:
            screen.fill(SCREEN_DEFAULT_COLOR)
        elif event.type == MOUSEBUTTONDOWN:
            print(pygame.mouse.get_pos())
            c_color = (randint(0, 255), randint(0, 255), randint(0, 255))
            c_pos = (randint(0, 500), randint(0, 500))
            c_r = randint(10, 100)
            pygame.draw.circle(screen, c_color, c_pos, c_r)
    pygame.display.update()