Python 中图像精灵无法在窗口显示的解决方法

有人在使用 Python 的 Pygame 库进行游戏开发时，遇到了图像精灵无法在窗口中显示的问题。经过初步排查，问题可能出在精灵的类定义或类调用中，但具体原因尚不清楚。以下是该用户的部分代码：

import pygame, sys
from pygame.locals import *

class Player(pygame.sprite.Sprite):

    def __init__(self, x, y):
        pygame.sprite.Sprite.__init__(self)

        self.image = pygame.image.load('Green circle png.png')
        self.rect = self.image.get_rect()
        self.rect.x = x
        self.rect.y = y

    def changespeed(self, x, y):
        self.change_x = x
        self.change_y = y

    def update_pos(self, x, y):
        old_x_pos = self.rect.x
        new_x_pos = old_x_pos + self.change_x
        self.rect.x = new_x_pos

        old_y_pos = self.rect.y
        new_y_pos = old_y_pos + self.change_y
        self.rect.x = new_y_pos

def main():

    pygame.init()

    thescreen = pygame.display.set_mode((windowwidth, windowheight))
    pygame.display.set_caption('Maze Game')
    thescreen.fill((BLACK))

    mainclock = pygame.time.Clock()

    running = True
    while running == True:
        for event in pygame.event.get():
            if event.type == QUIT:
                running = False
            if event.type == KEYDOWN:
                if (event.key == K_UP or event.key == K_w):
                    Player.changespeed = (-3, 0)
                elif (event.key == K_DOWN or event.key == K_s):
                    Player.changespeed = (3, 0)
                elif (event.key == K_LEFT or event.key == K_a):
                    Player.changespeed = (0, -3)
                elif (event.key == K_RIGHT or event.key == K_d):
                    Player.changespeed = (0, 3)
            if event.type == KEYUP:
                if (event.key == K_UP or event.key == K_w):
                    Player.changespeed = (0, 0)
                elif (event.key == K_DOWN or event.key == K_s):
                    Player.changespeed = (0, 0)
                elif (event.key == K_LEFT or event.key == K_a):
                    Player.changespeed = (0, 0)
                elif (event.key == K_RIGHT or event.key == K_d):
                    Player.changespeed = (0, 0)


        mainclock.tick(60)
        pygame.display.update()
    pygame.quit()

if __name__ == '__main__':
    main()

2、解决方案

在仔细分析了代码后，我们发现问题出在绘制精灵的代码中。在 Pygame 中，如果要将精灵显示在窗口中，需要将其添加到 SpriteGroup 中，然后在主循环中调用 SpriteGroup 的 update() 和 draw() 方法。在此例中，用户没有将精灵添加到 SpriteGroup 中，导致精灵无法显示。

要解决此问题，需要在代码中添加以下几行代码：

players = pygame.sprite.RenderUpdates()
players.add(Player(200,200))

将精灵添加到 RenderUpdates 组中后，还需要在主循环中调用 RenderUpdates 组的 update() 和 draw() 方法。在此例中，用户没有调用 RenderUpdates 组的 update() 方法，导致精灵无法更新位置。

修改后的主循环代码如下：

def mainloop():
    while running == True:
        pygame.display.update(players.draw(thescreen))
        for event in pygame.event.get():
            if event.type == QUIT:
                running = False
            if event.type == KEYDOWN:
                if (event.key == K_UP or event.key == K_w):
                    Player.changespeed = (-3, 0)
                elif (event.key == K_DOWN or event.key == K_s):
                    Player.changespeed = (3, 0)
                elif (event.key == K_LEFT or event.key == K_a):
                    Player.changespeed = (0, -3)
                elif (event.key == K_RIGHT or event.key == K_d):
                    Player.changespeed = (0, 3)
            if event.type == KEYUP:
                if (event.key == K_UP or event.key == K_w):
                    Player.changespeed = (0, 0)
                elif (event.key == K_DOWN or event.key == K_s):
                    Player.changespeed = (0, 0)
                elif (event.key == K_LEFT or event.key == K_a):
                    Player.changespeed = (0, 0)
                elif (event.key == K_RIGHT or event.key == K_d):
                    Player.changespeed = (0, 0)

        players.update()