python 键盘上下左右控制

bif="1.jpg"
mif="2.jpg"
import pygame,sys
from pygame.locals import *

pygame.init()

screen=pygame.display.set_mode((640,360),0,32)
background=pygame.image.load(bif).convert()
mouse_c=pygame.image.load(mif).convert_alpha()

x,y=0,0
movex,movey=0,0

while True:
    for event in pygame.event.get():
        if event.type ==QUIT:
            pygame.quit()
            sys.exit()
        if event.type==KEYDOWN:
            if event.key==K_LEFT:
                movex=-1
            if event.key==K_RIGHT:
                movex=+1
            elif event.key==K_UP:
                movey=-1
            elif event.key==K_DOWN:
                movey=+1
        if event.type==KEYUP:
            if event.key==K_LEFT:
                movex=0
            if event.key==K_RIGHT:
                movex=0
            elif event.key==K_UP:
                movey=0
            elif event.key==K_DOWN:
                movey=0

    x+=movex
    y+=movey
    
    screen.blit(background,(0,0))
    screen.blit(mouse_c,(x,y))
    
    pygame.display.update()