NameError: name 'KEYDOWN' is not defined

问题:

i am new to program with pygame and i have made this code:

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()

but when i am trying to use it it just saying:

      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

so please help me i very need it so much. i need an answer quick.

回答1:

KEYDOWN isn't defined in your code. You can add this to the beginning:

from pygame.locals import *

Or you can do this:

elif event.type == pygame.KEYDOWN

回答2:

Use this command while using pygame library

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

回答3:

just change this piece, then it should work :)

elif event.type == KEYDOWN: CHANGE TO: elif event.type == pygame.KEYDOWN: