Python pygame.event.get_pressed() 不更新

Question

我有一个程序可以绘制一个收缩的绿色圆圈，当您按p时，圆圈消失并出现一条红线。但是当我再次按 p 时，绿色圆圈应该重新出现，但事实并非如此。

每当我第一次按 p 后调用 pygame.event.get_pressed() 函数时，它总是返回相同的值。我是否必须使用某种键盘重置才能使 get_pressed() 方法再次正确读取？

这是我的代码:

import pygame
import time

BLACK = (0,0,0)
WHITE = (255,255,255)
GREEN = (0,255,0)
RED = (255,0,0)

pygame.init()

size = (700,700)
screen = pygame.display.set_mode(size)
screennumber = 1

pygame.display.set_caption("Game Test")

running = True
width = 350

clock = pygame.time.Clock()

while running:

for event in pygame.event.get():
    if event.type == pygame.QUIT:
        running = False

screen.fill(BLACK)

pressed = pygame.key.get_pressed()
print(pressed)

if pressed[pygame.K_p]:
    screennumber = 2
else:
    screennumber = 1

if screennumber == 1:

    pygame.draw.circle(screen,GREEN,[350,350], width,1)

    pygame.display.flip()

    if width>1:
        width = width-1

if screennumber == 2:

        time.sleep(0.25)
        pause = True
        while pause:
            pressed = pygame.key.get_pressed()
            print(pressed)
            if pressed[pygame.K_r]:
                pause = False

            pygame.draw.line(screen,RED,[0,0],[700,700],5)

            pygame.display.flip()

            clock.tick(21)


pygame.display.flip()

clock.tick(21)


pygame.quit()

谢谢!

Answer 1

使用 pygame.key.get_pressed 并不是实时处理按键的可靠方法。该函数返回一个字典，其中包含函数调用时键盘的状态。但是，如果在调用之间按下并释放某个键，则字典将与根本没有按下该键一样。检查用户是否按下某个键的更好方法是在事件循环中处理 pygame.KEYDOWN 事件。然后检查KEYDOWN是否是您想要的 key 。

这是您的程序版本，分为三个部分:1) 处理事件，2) 更新游戏元素，3) 绘制到屏幕。

import pygame
import time

BLACK = (0,0,0)
WHITE = (255,255,255)
GREEN = (0,255,0)
RED = (255,0,0)

pygame.init()

size = (700,700)
screen = pygame.display.set_mode(size)
pygame.display.set_caption("Game Test")

running = True
width = 350
paused = False

clock = pygame.time.Clock()

while running:

    # process all events
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False

        # -- HERE IS THE RELEVANT SECTION --
        if event.type == pygame.KEYDOWN:
            if event.key == pygame.K_p:
                paused = not(paused)

    # update everything
    if not paused:
        if width > 1:
            width = width-1

    # draw everything
    screen.fill(BLACK)
    if not paused:
        pygame.draw.circle(screen,GREEN,[350,350], width,1)
    else:
        pygame.draw.line(screen,RED,[0,0],[700,700],5)
    pygame.display.flip()

    # update the clock
    clock.tick(21)


pygame.quit()

如果您对此代码有任何疑问，请告诉我。