ship.py

import pygame
from pygame.sprite import Sprite

class Ship(Sprite):
	"""a class to manage the ship"""

	def __init__(self, ai_game):
		"""Initalize the ship and set its starting position"""
		super().__init__()
		self.screen = ai_game.screen
		self.screen_rect = ai_game.screen.get_rect()
		self.settings = ai_game.settings

		# load the ship image and get its rect.
		self.image = pygame.image.load('images/ship2.bmp')
		self.rect = self.image.get_rect()

		# Start each new ship at the bottom center of the screen
		self.rect.midbottom = self.screen_rect.midbottom

		# store a decimal value for the ship's horizontal position
		self.x = float(self.rect.x)

		# movement flag
		self.moving_right = False
		self.moving_left = False

	def update(self):
		"""update the ship's position based on the movement flag"""
		# update the ship's x value, not the rect
		if self.moving_right and self.rect.right < self.screen_rect.right:
			self.x += self.settings.ship_speed
		if self.moving_left and self.rect.left > 0:
			self.x -= self.settings.ship_speed

		# update rect object from self.x
		self.rect.x = self.x

	def blitme(self):
		"""draw the ship at its current location"""
		self.screen.blit(self.image, self.rect)

	def center_ship(self):
		"""center the ship on the screen"""
		self.rect.midbottom = self.screen_rect.midbottom
		self.x = float(self.rect.x)