Pygame:当按下键时，玩家不会移动

import pygame
from pygame.locals import *

pygame.init()

window_width = 800
window_height = 600
player_x = 400
player_y = 300

window = pygame.display.set_mode((window_width, window_height))
pygame.display.set_caption("My Game")

running = True
while running:
    for event in pygame.event.get():
        if event.type == QUIT:
            running = False
        elif event.type == KEYDOWN:
            if event.key == K_UP:
                # 处理向上移动的逻辑
                pass
            elif event.key == K_DOWN:
                # 处理向下移动的逻辑
                pass
            elif event.key == K_LEFT:
                # 处理向左移动的逻辑
                pass
            elif event.key == K_RIGHT:
                # 处理向右移动的逻辑
                pass