pygame

import pygame
from pygame.locals import (K_SPACE, KEYDOWN, QUIT)


class Obj:
    def __init__(self):
        self.x = 400
        self.y = 300
        self.dir = 0
        
    def update(self):   # 更新位置
        if self.dir == 0:
            self.up()
        elif self.dir == 1:
            self.right()
        elif self.dir == 2:
            self.down()
        else:
            self.left()
            
    def up(self):       # 上
        self.y -= 1
        if self.y <= 10:
            self.dir = 1

    def right(self):    # 右
        self.x += 1
        if self.x >= 790:
            self.dir = 2

    def down(self):     # 下
        self.y += 1
        if self.y >= 590:
            self.dir = 3

    def left(self):     # 左
        self.x -= 1
        if self.x <= 10:
            self.dir = 0


class App:
    def __init__(self, WIDTH, HEIGHT,TEXT_HEIGHT):
        pygame.init()
        self.WIDTH = WIDTH
        self.HEIGHT = HEIGHT
        self.TEXT_HEIGHT = TEXT_HEIGHT
        self.screen = pygame.display.set_mode((WIDTH, HEIGHT+TEXT_HEIGHT))
        self.WHITE = (255, 255, 255)
        self.BLACK = (0, 0, 0)
        self.BLUE = (0, 0, 200)

    def pause(self):    # 暂停
        self.showtext("press space to play")
        pygame.display.flip()
        
        while True:
            for event in pygame.event.get():
                if event.type == KEYDOWN:
                    if event.key == K_SPACE:    # 按空格恢复
                        return True
                elif event.type == pygame.QUIT: # 退出
                    return False

    def init(self): # 初始场景
        self.screen.fill(self.WHITE)

    def showtext(self,text):    # 显示提示文字
        bar = pygame.Surface((self.WIDTH, self.TEXT_HEIGHT))  # 字的背景条的大小
        bar.fill(self.BLUE)   # 颜色
        rect = bar.get_rect()
        self.screen.blit(bar, (0, self.HEIGHT))  # 显示位置

        font = pygame.font.Font('freesansbold.ttf',self.TEXT_HEIGHT)  # 字体和大小
        TextSurface = font.render(text, True, self.BLACK)    # 要显示的字和颜色
        TextRect = TextSurface.get_rect()
        TextRect.center = ((self.WIDTH/2),(self.HEIGHT+self.TEXT_HEIGHT/2)) # 显示位置
        self.screen.blit(TextSurface, TextRect) 

    def run(self):
        obj = Obj()
        self.init() # 初始场景
        running = self.pause()  # 刚开始先暂停
        
        while running:
            for event in pygame.event.get():
                if event.type == KEYDOWN:
                    if event.key == K_SPACE:    # 按空格暂停
                        running = self.pause()
                
                elif event.type == pygame.QUIT: # 退出
                    running = False

            
            self.screen.fill(self.WHITE)   # 背景
            self.showtext("press space to pause")
            # --------------
            surf = pygame.Surface((50, 50))
            surf.fill((0, 0, 0))
            rect = surf.get_rect()
            self.screen.blit(surf, (obj.x, obj.y))
            # --------------
            pygame.display.flip()   # 画
            obj.update()    # 更新

        pygame.quit()   # 退出循环后，结束


if __name__=='__main__':
    WIDTH = 800
    HEIGHT = 600
    TEXT_HEIGHT = 60
    App(WIDTH, HEIGHT, TEXT_HEIGHT).run()