python - NameError：未定义名称“KEYDOWN”

Question

我是使用 PyGame 编程的新手，我编写了以下代码：

import sys, pygame
pygame.init()
size = width, height = 800, 600
speed = [2, 2]
black = 1, 1, 1
screen = pygame.display.set_mode(size)
ball = pygame.image.load("ball.bmp")
ballrect = ball.get_rect()
player1 = pygame.image.load("player1.png")
player1rect = player1.get_rect()
mod_x = mod_y = 0
while 1:
    for event in pygame.event.get():
        if event.type == pygame.QUIT: 
            sys.exit()
        elif event.type == KEYDOWN:
            if event.key == K_W:
                movex = 2
            if event.key == K_S:
                movex = -2
    ballrect = ballrect.move(speed)
    if ballrect.left < 0 or ballrect.right > width:
        speed[0] = -speed[0]
    if ballrect.top < 0 or ballrect.bottom > height:
        speed[1] = -speed[1]
    screen.fill(black)
    screen.blit(ball, ballrect)
    screen.blit(player1, player1rect)
    pygame.display.flip()

但是当我执行我的代码时，我得到了这个错误：

File "C:\Users\User\Documents\Pong\pong.py", line 22, in <module>
    elif event.type == KEYDOWN:
NameError: name 'KEYDOWN' is not defined
             ^
SyntaxError: invalid syntax

请帮我。我非常需要它，我需要一个快速的答案。

Answer 1

KEYDOWN未在您的代码中定义。您可以将其添加到开头：

from pygame.locals import *

或者你可以这样做：

elif event.type == pygame.KEYDOWN

Answer 2

在使用 pygame 库时使用此命令

...
elif event.type == pygame.KEYDOWN
...

Answer 3

只需更改此部分，然后它应该可以工作:)

elif event.type == KEYDOWN：更改为：elif event.type == pygame.KEYDOWN：