Pygame game practice four

@Python programming from entry to practice exercises Python project

Nine, add the Play button

First, create a Button class

Let the beginning of the game inactive

# game_stats.py
# --snip--

self.game_active = False

# def reset_stats(self):
# --snip--

solid rectangular button class is tagged, the "play" as the character string rendered image, centered on the top of the rectangular

# button.py
import pygame.font


class Button():

    def __init__(self, ai_settings, screen, msg):
        """初始化按钮的属性"""
        self.screen = screen
        self.screen_rect = screen.get_rect()

        # 设置按钮的尺寸和其他属性
        self.width, self.height = 200, 50
        self.button_color = (0, 0, 0)
        self.text_color = (255, 255, 255)
        self.font = pygame.font.SysFont(None, 48) # 指定字体

        # 创建按钮的rect对象，并使其居中
        self.rect = pygame.Rect(0, 0, self.width, self.height)
        self.rect.center = self.screen_rect.center

        # 按钮的标签只需创建一次，即将字符串msg渲染为图像
        self.prep_msg(msg)

    def prep_msg(self, msg):
        """将msg渲染为图像，并使其在居中"""
        self.msg_image = self.font.render(msg, True, self.text_color,
                                          self.button_color)  # 渲染为图像
        self.msg_image_rect = self.msg_image.get_rect()
        self.msg_image_rect.center = self.rect.center  # 使文字形成的图像居中

    def draw_button(self):
        # 绘制一个用颜色填充的按钮，再绘制文本图像，使其在上方
        self.screen.fill(self.button_color, self.rect)
        self.screen.blit(self.msg_image, self.msg_image_rect)

Second, draw a button

Create an instance alien_invasion.py, modify up_screen (), the game is inactive display button

# alien_invasion.py
# --snip--
    # 创建play按钮
    play_button = Button(ai_settings, screen, "Play")

    # 开始游戏主循环
    while True:
    # --snip--
        # 每次循环重绘窗口并更新屏幕
        gf.update_screen(ai_settings, screen, stats, ship, passenger_group, bullet_group,play_button)

# game_functions.py
# --snip--

    # 如果游戏处于非活动状态，就绘制Play按钮
    if not stats.game_active:
        play_button.draw_button()

# --snip--

Third, click the button

When the player clicks the button, the game should reset the statistics, ensure that the next game is not repeated. And only when False, click on the activation state to be effective in the game.

# game_functions.py
#   for event in pygame.event.get():
#       if event.type == pygame.QUIT:
#          sys.exit()

#    --snip--
        elif event.type == pygame.MOUSEBUTTONDOWN:
            mouse_x, mouse_y = pygame.mouse.get_pos()
            check_play_button(ai_settings, screen, stats, play_button, ship,
                              passenger_group, bullet_group, mouse_x, mouse_y)


def check_play_button(ai_settings, screen, stats, play_button, ship,
                      passenger_group, bullet_group, mouse_x, mouse_y):
    """在玩家单击Play按钮时开始游戏"""
    button_clicked = play_button.rect.collidepoint(mouse_x, mouse_y)
    if button_clicked and not stats.game_active:  # 检查鼠标点击位置是否在play范围内
        # 隐藏光标
        pygame.mouse.set_visible(False)
        # 重置游戏统计信息
        stats.reset_stats()
        stats.game_active = True

        # 清空外星人列表和子弹列表
        passenger_group.empty()
        bullet_group.empty()

        # 创建一群新的外星人，并在飞船居中
        create_fleet(ai_settings, screen, ship, passenger_group)
        ship.center_ship()

Note, in the modification alien_invasion.py, check_events the parameter, game_functions.py sync with.