text: import pygame
  
  class Ship():
  	def __init__(self, ai_settings, screen):
  		"""初始化飞船并设置其初始位置"""
  		self.screen = screen
  		self.ai_settings = ai_settings
  
  		#加载飞船图像并获取其外接矩形
  		self.image = pygame.image.load('ship.bmp')
  		self.rect = self.image.get_rect()
  		self.screen_rect = screen.get_rect()
  
  		#将每艘新飞船放在屏幕底部中央
  		self.rect.centerx = self.screen_rect.centerx
  		self.rect.bottom = self.screen_rect.bottom
  
  		#在飞船的属性center中存储小数值
  		self.center = float(self.rect.centerx)
  
  		self.moving_right = False
  		self.moving_left = False
  
  	def update(self):
  		"""根据移动标志调整飞船的位置"""
  		if self.moving_right and self.rect.right < self.screen_rect.right:
  			self.center += self.ai_settings.ship_speed_factor
  		if self.moving_left and self.rect.left > 0:
  			self.center -= self.ai_settings.ship_speed_factor
  
  		#根据self.center更新rect对象
  		self.rect.centerx = self.center
  
  	def blitme(self):
  		"""在指定位置绘制飞船"""
  		self.screen.blit(self.image, self.rect)
  