ship.py

import pygame
from pygame.sprite import Sprite

class Ship(Sprite):

    def __init__(self, ai_settings, screen):
        """Inicializa a espaconave e define sua posicao inicial"""
        super(Ship, self).__init__()
        self.screen = screen
        self.ai_settings = ai_settings

        # Carrega a imagem da espaconave e obtem seu rect
        self.image = pygame.image.load('images/ship.bmp')
        self.rect = self.image.get_rect()
        self.screen_rect = screen.get_rect()

        # Inicia cada nova espaconave na parte inferior central da tela
        self.rect.centerx = self.screen_rect.centerx
        self.rect.bottom = self.screen_rect.bottom
        self.center = float(self.rect.centerx)

        # Flag de movimento
        self.moving_right = False
        self.moving_left = False


    def update(self):
        """Atualiza a posicao da espaconave de acordo com a flag
        de movimento."""

        # Atualiza o valor do centro da espaconave, e nao o rectangulo
        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

        # Atualiza o objecto reac de acordo com self.center
        self.rect.centerx = self.center

    def blitme(self):
        """Desenha a espaconave em sua posicao actual"""
        self.screen.blit(self.image, self.rect)

    def center_ship(self):
        """Centraliza a espaconvae na tela"""
        self.center = self.screen_rect.centerx