Pygame icon（）函数不更改全局变量B

Question

我有一个函数，允许用户单击图标并设置布尔值，以便主循环知道要执行的操作。该代码将用作单击喷枪图标->；将airbrushMode设置为true->；返回airbrushMode，以便paintScreen()可以检测到它->；执行while循环中由airbrushMode设置的操作。我添加了打印语句来定位问题。该变量确实会更改，但不会返回该变量，而且喷枪功能不起作用。当我在paintScreen()内将airbrushMode设置为true时，它确实起作用，但在函数内和函数外将其设置为false都不起作用

主要功能

def paintScreen():
    airbrushMode = False
    paint = True
    gameDisplay.fill(cyan)
    message_to_screen('Welcome to PyPaint', black, -300, 'large')
    cur = pygame.mouse.get_pos()
    click = pygame.mouse.get_pressed()
    pygame.draw.rect(gameDisplay, white, (50, 120, displayWidth - 100, displayHeight - 240))
    while paint:
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                pygame.quit()
                quit()

        button('X', 20, 20, 50, 50, red, lightRed, action = 'quit')
        icon(airbrushIcon, white, 50, displayHeight - 101, 51, 51, white, grey, 'airbrush')
        icon(pencilIcon, white, 140, displayHeight - 101, 51, 51, white, grey, 'pencil')
        icon(calligraphyIcon, white, 230, displayHeight - 101, 51, 51, white, grey, 'calligraphy')
        pygame.display.update()
        if cur[0] >= 50 <= displayWidth - 50 and cur[1] >= 120 <= displayHeight - 120:
            if airbrushMode == True:
                airbrush()

创建图标并检测动作，然后返回的函数

def icon(icon, colour, x, y, width, height, inactiveColour, activeColour, action = None):
    cur = pygame.mouse.get_pos()
    click = pygame.mouse.get_pressed()
    if x + width > cur[0] > x and y + height > cur[1] > y:#if the cursor is over the button
        pygame.draw.rect(gameDisplay, activeColour, (x, y, width, height))
        gameDisplay.blit(icon, (x, y))
        if click[0] == 1 and action != None: #if clicked
            print('click')
            if action == 'quit':
                pygame.quit()
                quit()
            elif action == 'airbrush':
                airbrushMode = True
                print('airbrush set')
                return airbrushMode
                print('airbrush active')

Answer 1

与其在icon()中检查事件，不如在按下按钮时发布事件，代码可能会更流畅

def icon(icon, colour, x, y, width, height, inactiveColour, activeColour, action = None):
    cur = pygame.mouse.get_pos()
    click = pygame.mouse.get_pressed()
    if x + width > cur[0] > x and y + height > cur[1] > y:#if the cursor is over the button
        pygame.draw.rect(gameDisplay, activeColour, (x, y, width, height))
        gameDisplay.blit(icon, (x, y))
        if click[0] == 1 and action != None: #if clicked
            print('click')
            pygame.event.post( pygame.USEREVENT + 1, {} )

然后在主循环中处理这些问题：

while paint:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            pygame.quit()
            quit()
        elif event.type == pygame.USEREVENT + 1
            airbrushMode = True

如果是我，我会制作一套自己的事件类型：

import enum

...

class MyEvents( enum.Enum ):
    AIRBRUSH = pygame.USEREVENT + 1
    PEN      = pygame.USEREVENT + 2
    PENCIL   = pygame.USEREVENT + 3

允许：

pygame.event.post( MyEvents.AIRBRUSH, {} )

...

elif ( event.type == MyEvents.AIRBRUSH ):
    airbrushMode = True

Answer 2

您的问题是icon不试图更改任何全局变量；它严格地处理它的输入参数和局部变量。如果希望它更改自身范围之外的变量，则需要添加

global airbrushMode

在你的功能的顶端

此外，如果希望paintScreen识别全局变量，则必须具有该变量的全局存在性（顶级用法），或者paintScreen还需要global声明

有关详细信息，请在Python中查找全局变量