ship

ship.py

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+import pygame
+from pygame.sprite import Sprite
+
+class Ship(Sprite):
+
+    def __init__(self,ai_settings, screen):
+        """初始化飞船并设置其初始值"""
+        super(Ship, self).__init__()
+        self.screen = screen
+        self.ai_seetings = ai_settings
+
+        # 加载飞船图像并获取其外接矩形
+        self.image = pygame.image.load("./images/ship.bmp")
+        self.rect = self.image.get_rect()
+        self.screen_rect = screen.get_rect()
+
+        # 将每艘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)
+        # 移动标志
+        self.moving_right = False
+        self.moving_left = False
+
+    def update(self):
+        """根据移动标志调整飞船的位置"""
+        # 更新飞船呢的center值而不是rect
+        if self.moving_right and self.rect.right < self.screen_rect.right:
+            self.center += self.ai_seetings.ship_speed_factor
+        if self.moving_left and self.rect.left > 0:
+            self.center -= self.ai_seetings.ship_speed_factor
+        # 根据self.center更新rect的对象
+        self.rect.centerx = self.center
+
+    def blitme(self):
+        """在指定位置绘制飞船"""
+        self.screen.blit(self.image, self.rect)
+
+    def center_ship(self):
+        """让飞船在屏幕中央"""
+        self.center = self.screen_rect.centerx