class Background(GameSprite):
    """游戲背景精靈"""
    def __init__(self,image_path, is_alt=False):
        # 1.調(diào)用父類方法實現(xiàn)精靈的創(chuàng)建(image/rect/speed)
        super().__init__(image_path)
        # 2.判斷是否是交替圖像，如果是，需要設(shè)置初始位置
        if is_alt is True:
            self.rect.x = self.rect.width
        else:
            self.rect.x = 0
 
    def update(self):
        # 1.調(diào)用父類的方法實現(xiàn)
        super().update()
        # 2.判斷是否移出屏幕，如果移出屏幕，將圖像設(shè)置到屏幕的上方
        if self.rect.x <= -SCREEN_RECT.width:
            self.rect.x = self.rect.width

    def __create_sprites(self):
        """創(chuàng)建背景精靈和精靈組"""
 
        # 天空背景
        bg1 = Background("./images/background_16_9.png", False)
        bg2 = Background("./images/background_16_9.png", True)
        self.back_group = pygame.sprite.Group(bg1, bg2)
 
        # 內(nèi)層海洋背景
        sea_bg_1 = Background("./images/sea_bg_1_16_9.png", False)
        sea_bg_2 = Background("./images/sea_bg_1_16_9.png", True)
        #移動速度
        sea_bg_1.speed = 2
        sea_bg_2.speed = 2
        sea_bg_1.rect.bottom = SCREEN_RECT.height
        sea_bg_2.rect.bottom = SCREEN_RECT.height
        self.sea_bg_ground_1 = pygame.sprite.Group(sea_bg_1, sea_bg_2)
 
        # 外層海洋背景
        sea_bg_3 = Background("./images/sea_bg_2_16_9.png", False)
        sea_bg_4 = Background("./images/sea_bg_2_16_9.png", True)
        # 移動速度
        sea_bg_3.speed = 3
        sea_bg_4.speed = 3
        sea_bg_3.rect.bottom = SCREEN_RECT.height
        sea_bg_4.rect.bottom = SCREEN_RECT.height
        self.sea_bg_ground_2 = pygame.sprite.Group(sea_bg_3, sea_bg_4)

        # 使用鍵盤提供的方法獲取鍵盤按鍵 - 按鍵元組
        keys_pressed = pygame.key.get_pressed()
        # 判斷用戶按下鍵盤空格鍵
        if keys_pressed[pygame.K_SPACE]:
            # 跳起
            self.man.speed = -10
        else:
            # 下降
            self.man.speed = 10

    def update(self):
        # 猴子在水平方向移動
        self.rect.y += self.speed
        # 控制猴子不能移出屏幕
        if self.rect.y < 0:
            self.rect.y = 0
        elif self.rect.bottom > self.bottom_to_ground:
            self.rect.bottom = self.bottom_to_ground