我正在按我的学分屏幕上的一个按钮，以便在按下时返回到开始屏幕。我有一个带有“事件”作为参数的按钮功能，但是当我在信用场景中使用它时。但是，会发生此错误：“ UnboundLocalError：分配前引用了本地变量'事件'”。我不明白，“事件”甚至都不是变量。有人知道如何解决这个问题吗？
File "/Users/qingduliu/PycharmProjects/Pygame3/Shoot 'em Up.py", line 355, in credits
button(events, 10, 10, 120, 60, WHITE, GRAY, 'back')
UnboundLocalError: local variable 'events' referenced before assignment
代码
def button(events, x, y, width, height, ic, ac, action=None):
mouse = pygame.mouse.get_pos()
# print(mouse)
if x + width > mouse[0] > x and y + height > mouse[1] > y:
pygame.draw.rect(screen, ac, (x, y, width, height), 0)
if events.type == pygame.MOUSEBUTTONDOWN and action is not None:
if action == 'play':
game_loop()
elif action == 'credits':
credits()
elif action == 'instructions':
instructions()
elif action == 'back':
start_screen()
elif action == 'quit':
pygame.quit()
quit()
else:
pygame.draw.rect(screen, ic, (x, y, width, height), 0)
def start_screen():
start = True
while start:
clock.tick(FPS)
for events in pygame.event.get():
if events.type == pygame.QUIT:
pygame.quit()
quit()
screen.blit(background, background_rect)
pygame.transform.scale(player_img, (50, 38))
player_img.set_colorkey(BLACK)
screen.blit(player_img, (10, HEIGHT - 120))
screen.blit(player_img, (WIDTH - 110, HEIGHT - 120))
bullet_img.set_colorkey(BLACK)
screen.blit(bullet_img, (55, 400))
screen.blit(bullet_img, (415, 400))
screen_meteor.set_colorkey(BLACK)
screen.blit(screen_meteor, (5, 220))
screen.blit(screen_meteor, (WIDTH - 105, 220))
boss_img.set_colorkey(BLACK)
pygame.transform.scale(boss_img, (50, 38))
screen.blit(boss_img, (190, 25))
button(events, 180, 285, 120, 60, BLUE, LIGHT_BLUE, 'play')
button(events, 202, HEIGHT - 150, 80, 40, WHITE, GRAY, 'quit')
button(events, 310, 45, 140, 30, WHITE, GRAY, 'credits')
button(events, 20, 45, 140, 30, WHITE, GRAY, 'instructions')
draw_text(screen, "Shoot 'Em Up", 80, WIDTH / 2, HEIGHT / 4, WHITE)
draw_text(screen, "Instructions", 30, 90, 53, BLACK)
draw_text(screen, "Credits", 35, 378, 50, BLACK)
draw_text(screen, "Play", 55, WIDTH / 2, HEIGHT / 2, WHITE)
draw_text(screen, "Quit", 30, WIDTH / 2, HEIGHT - 137, BLUE)
pygame.display.flip()
def credits():
credits = True
while credits:
clock.tick(FPS)
for events in pygame.event.get():
if events.type == pygame.QUIT:
pygame.quit()
quit()
screen.blit(background, background_rect)
draw_text(screen, "Credits", 100, WIDTH / 2, 15, WHITE)
draw_text(screen, "Game Template:", 60, WIDTH / 2, 95, WHITE)
draw_text(screen, "Kids Can Code, Shmup, Chris Bradfield", 35, WIDTH / 2, 155, WHITE)
draw_text(screen, "Youtube Channel", 30, WIDTH / 2, 195, WHITE)
draw_text(screen, "https://www.youtube.com/channel/UCNaPQ5uLX5iIEHUCLmfAgKg", 20, WIDTH / 2, 220, WHITE)
draw_text(screen, "Blog", 30, WIDTH / 2, 245, WHITE)
draw_text(screen, "http://kidscancode.org/blog/tags/pygame/", 20, WIDTH / 2, 270, WHITE)
draw_text(screen, "Music:", 60, WIDTH / 2, 300, WHITE)
draw_text(screen, "Frozen Jam by tgfcoder", 45, WIDTH / 2, 345, WHITE)
draw_text(screen, "Twitter", 30, WIDTH / 2, 380, WHITE)
draw_text(screen, "<https://twitter.com/tgfcoder>", 20, WIDTH / 2, 403, WHITE)
draw_text(screen, "licensed under CC-BY-3 <http://creativecommons.org/licenses/by/3.0/>", 15, WIDTH / 2, 425, WHITE)
draw_text(screen, "Art:", 60, WIDTH / 2, 450, WHITE)
draw_text(screen, "Kenney.nl", 35, WIDTH / 2, 490, WHITE)
draw_text(screen, "https://opengameart.org/", 20, WIDTH / 2, 520, WHITE)
draw_text(screen, "Background https://imgur.com/bHiPMju by Chris Bradfield", 20, WIDTH / 2, 540, WHITE)
draw_text(screen, "Thank You for all your help and hard work!", 32, WIDTH / 2, 560, RED)
button(events, 10, 10, 120, 60, WHITE, GRAY, 'back')
draw_text(screen, "Back", 25, 13, 13, WHITE)
pygame.display.flip()
答案 0 :(得分：0)
button(events, 180, 285, 120, 60, BLUE, LIGHT_BLUE, 'play')
在第一个代码块中，您引用了for循环之外的事件，该循环定义了events变量
答案 1 :(得分：0)
您必须将按钮移至事件循环，因为按钮必须检查每个事件。
因为使用了用鼠标检查冲突并在一个代码中绘制按钮的功能，所以必须将事件循环移到按钮上。
clock.tick(FPS)
# - draw background, etc. -
screen.blit(background, background_rect)
pygame.transform.scale(player_img, (50, 38))
player_img.set_colorkey(BLACK)
screen.blit(player_img, (10, HEIGHT - 120))
screen.blit(player_img, (WIDTH - 110, HEIGHT - 120))
bullet_img.set_colorkey(BLACK)
screen.blit(bullet_img, (55, 400))
screen.blit(bullet_img, (415, 400))
screen_meteor.set_colorkey(BLACK)
screen.blit(screen_meteor, (5, 220))
screen.blit(screen_meteor, (WIDTH - 105, 220))
boss_img.set_colorkey(BLACK)
pygame.transform.scale(boss_img, (50, 38))
screen.blit(boss_img, (190, 25))
# - buttons - events + draw -
for events in pygame.event.get():
if events.type == pygame.QUIT:
pygame.quit()
quit()
button(events, 180, 285, 120, 60, BLUE, LIGHT_BLUE, 'play')
button(events, 202, HEIGHT - 150, 80, 40, WHITE, GRAY, 'quit')
button(events, 310, 45, 140, 30, WHITE, GRAY, 'credits')
button(events, 20, 45, 140, 30, WHITE, GRAY, 'instructions')
# - draw text on buttons -
draw_text(screen, "Shoot 'Em Up", 80, WIDTH / 2, HEIGHT / 4, WHITE)
draw_text(screen, "Instructions", 30, 90, 53, BLACK)
draw_text(screen, "Credits", 35, 378, 50, BLACK)
draw_text(screen, "Play", 55, WIDTH / 2, HEIGHT / 2, WHITE)
draw_text(screen, "Quit", 30, WIDTH / 2, HEIGHT - 137, BLUE)
# - send all on screen -
pygame.display.flip()
代码很奇怪，因为现在它为每个事件多次绘制按钮。但是要更改它，您将必须将按钮拆分为两个功能，或者创建具有两个功能的类Button-draw()和handle_event()
编辑：您可以尝试使用click = pygame.mouse.get_pressed()和lick[0] == 1代替events，这样就不必进入for events循环了，但是当您删除按钮并将新按钮放在同一位置时，可能会出现问题。 Python会如此快地执行操作，以至于您仍然会按住按钮，而python会认为您已按下了新按钮。
def button(x, y, width, height, ic, ac, action=None):
mouse = pygame.mouse.get_pos()
click = pygame.mouse.get_pressed()
# print(mouse)
if x + width > mouse[0] > x and y + height > mouse[1] > y:
pygame.draw.rect(screen, ac, (x, y, width, height), 0)
if click[0] == 1 and action is not None:
if action == 'play':
game_loop()
elif action == 'credits':
credits()
elif action == 'instructions':
instructions()
elif action == 'back':
start_screen()
elif action == 'quit':
pygame.quit()
quit()
else:
pygame.draw.rect(screen, ic, (x, y, width, height), 0)
您可以分配给action函数名称，而不是文本'“ credits” ,“指令” ect. and then you can run it as action（）`
def button(x, y, width, height, ic, ac, action=None):
mouse = pygame.mouse.get_pos()
click = pygame.mouse.get_pressed()
# print(mouse)
if x + width > mouse[0] > x and y + height > mouse[1] > y:
pygame.draw.rect(screen, ac, (x, y, width, height), 0)
if click[0] == 1 and action is not None:
action()
else:
pygame.draw.rect(screen, ic, (x, y, width, height), 0)
button(180, 285, 120, 60, BLUE, LIGHT_BLUE, game_loop)
button(310, 45, 140, 30, WHITE, GRAY, credits)
button(20, 45, 140, 30, WHITE, GRAY, instructions)
button(202, HEIGHT - 150, 80, 40, WHITE, GRAY, game_quit)
def game_quit():
pygame.quit()
quit()
button(..., start_screen)