代码如下：
import pygame
from pygame.locals import *
sc=pygame.display.set_mode((700,460))
x,y=pygame.mouse.get_pos()
isHold=False
while True:
    for e in pygame.event.get():
        if e.type==QUIT:
            pygame.quit()
        if e.type==MOUSEBUTTONDOWN:
            x,y=pygame.mouse.get_pos()
            isHold=True
        if e.type==MOUSEBUTTONUP:
            isHold=False
    if isHold:
        pygame.draw.line(sc,(255,255,255),(x,y),pygame.mouse.get_pos(),1)
        x,y=pygame.mouse.get_pos()
    pygame.display.update()