class plane(pygame.sprite.Sprite):
    # input the image, animate's frame and position
    def __init__(self, target, frame, pos=(0, 0)):
        pygame.sprite.Sprite.__init__(self)
        self.image = pygame.image.load(target).convert_alpha()
        self.main_image = self.image
        self.rect = self.image.get_rect()
        self.frame = frame
        self.count = 0
        self.rect.topleft = pos
        self.oriRect = (self.image.get_rect().width, self.image.get_rect().height)
    # judge the parity of frame to zoom in and out
    def update(self):
        if self.count % 2 == 0:
            self.count = 1
            self.main_image = pygame.transform.scale2x(self.image)
        else:
            self.count = 0
            self.main_image = pygame.transform.scale(self.image, self.oriRect)
        self.image = self.main_image

pln = plane(plnjpg, 2, (100, 100))
group = pygame.sprite.Group()
group.add(pln)

while True:
    screen.blit(bg, (0, 0))
    group.update()
    group.draw(screen)
    pygame.display.update()
    pygame.time.wait(500)
    # delay 500ms
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            pygame.quit()



忙了半个月。终于又可以开始学了