alien.py

@@ -58,4 +58,13 @@ class Alien(Sprite):
                 pygame.draw.rect(screen,(0,230,0),((380,100),(500,10)))
             def check_edgrs(self):
                 """如果外星人位于屏幕边缘就返回True"""
+                screen_rect=self.screen.get_rect()
+                if self.rect.right>=screen_rect.right:
+                    return True
+                elif self.rect.left<=0:
+                    return True
+            def update(self):
+                """向左向右移动外星人"""
+                self.x+=(self.ai_settings.alien_speed_factor*self.ai_settings.bossalien_direction)
+                self.rect.x=self.x