player.update 不会接受按键输入并使角色移动 pygame

Question

I am new to pygame and this code I created by following a tutorial is not working. The white box i made on the screen should be moving with my arrow keys but its not. Does anyone know why? Also can someone explain what self means in the class and defs?

import pygame
from pygame.locals import (
    K_UP,
    K_DOWN,
    K_LEFT,
    K_RIGHT,
    K_ESCAPE,
    KEYDOWN,
    QUIT,
)

pygame.init()

SCREEN_WIDTH = 800
SCREEN_HEIGHT = 600

screen = pygame.display.set_mode((SCREEN_WIDTH, SCREEN_HEIGHT))



#Define a player object by extending pygame.sprite.Sprite
# The surface drawn on the screen is now an attribute of Player

class Player(pygame.sprite.Sprite):
    def __init__(self):
        super(Player,self).__init__()
        self.surf = pygame.Surface((75,25))
        self.surf.fill((255,255,255))
        self.rect = self.surf.get_rect()

    def update(self, pressed_keys):
        if pressed_keys[K_UP]:
            self.rect.move_ip(0,-5)
        if pressed_keys[K_DOWN]:
            self.rect.move_ip(0,5)
        if pressed_keys[K_LEFT]:
            self.rect.move_ip(-5,0)
        if pressed_keys[K_RIGHT]:
            self.rect.move_ip(5,0)
    


#Instantiate player        


pygame.init()

player = Player()


#keeps main loop running
running = True

#main loop
while running:
    for event in pygame.event.get():
        #Did user hit a key?
        if event.type == KEYDOWN:
            # Was it the escape key? if so, exit loop
            if event.key == K_ESCAPE:
                running = False


        elif event.type == QUIT:
            running = False



    pressed_keys = pygame.key.get_pressed()

    player.update(pressed_keys)

    screen.fill((0,0,0))

    screen.blit(player.surf,(SCREEN_WIDTH/2,SCREEN_HEIGHT/2))

    pygame.display.flip()


    

    







   

I tried to make the block move by clicking the arrow keys.

Answer 1

You always draw the player in the center of the screen:

 screen.blit(player.surf,(SCREEN_WIDTH/2,SCREEN_HEIGHT/2))

You have to draw the player at player.rect :

screen.blit(player.surf, player.rect)

---

However, since you use pygame.sprite.Sprite you should also use pygame.sprite.Group and you should limit the frames per second with pygame.time.Clock.tick :

clock = pygame.time.Clock()
player = Player()
spriteGroup = pygame.sprite.Group()
spriteGroup.add(player)

running = True
while running:
    clock.tick(60)
    for event in pygame.event.get():
        if event.type == KEYDOWN:
            if event.key == K_ESCAPE:
                running = False
        elif event.type == QUIT:
            running = False

    pressed_keys = pygame.key.get_pressed()
    player.update(pressed_keys)

    screen.fill((0,0,0))
    spriteGroup.draw(screen)
    pygame.display.flip()