# 导入pygame和sys模块

import pygame,sys

# 初始化pygame、生成屏幕对象screen、显示标题字幕

pygame.init()

screen = pygame.display.set_mode((500,500))

pygame.display.set_caption('hello world')

# 在屏幕(0, 0)的位置上绘制一个(50*50)大小的矩形

# 获取屏幕对象的矩形坐标

# 然后把矩形移动到屏幕指定的初始位置(屏幕正中央)

player = pygame.Rect(0, 0, 50, 50)

screen_rect = screen.get_rect()

player.centerx = screen_rect.centerx

player.centery = screen_rect.centery

# 设置上下左右移动标记，实现方块在按键以后持续移动

# 移动速度为 0.1 [否则移动太快无法看清楚方块的移动]

# 设置颜色值

moveLeft = False

moveRight = False

moveUp = False

moveDown = False

MOVESPEED = 0.1

BLACK=(0,0,0)

WHITE=(255,255,255)

# 因为centerx和centery不能存储小数，所以要设置中间变量

player_x = float(player.centerx)

player_y = float(player.centery)

# 进入游戏大循环

while True:

# 侦听事件，响应退出操作

for event in pygame.event.get():

if event.type==pygame.QUIT:

pygame.quit()

sys.exit()

# 侦听事件，响应按键操作

# 如果按下 键，则修改移动标记为True实现持续移动

elif event.type == pygame.KEYDOWN:

if event.key == pygame.K_LEFT:

moveLeft = True

elif event.key == pygame.K_RIGHT:

moveRight = True

elif event.key == pygame.K_UP:

moveUp = True

elif event.key==pygame.K_DOWN:

moveDown = True

# 侦听事件，响应松键操作

# 如果松开键，则修改移动标记为False停止移动

elif event.type == pygame.KEYUP:

if event.key == pygame.K_LEFT:

moveLeft = False

elif event.key == pygame.K_RIGHT:

moveRight = False

elif event.key == pygame.K_UP:

moveUp = False

elif event.key == pygame.K_DOWN:

moveDown = False

# 如果移动标记为True并且方块player没有越过屏幕边界，那么持续移动

# 将中间变量的值存储到centerx和centery中去

# 从而改变方块的位置

if moveDown and player.bottom < screen_rect.bottom:

player_y += MOVESPEED

player.centery = player_y

if moveUp and player.top > screen_rect.top:

player_y -= MOVESPEED

player.centery = player_y

if moveLeft and player.left > screen_rect.left:

player_x -= MOVESPEED

player.centerx = player_x

if moveRight and player.right < screen_rect.right:

player_x += MOVESPEED

player.centerx = player_x

# 每次循环都用白色填充屏幕

# 么次循环重新绘制player方块

# 每次循环都让元素在屏幕上可见

screen.fill(WHITE)

pygame.draw.rect(screen, BLACK, player)

pygame.display.flip()