如何更新 function 之外的颜色变量并更新窗口/画布？ (tkinter)

Question

所以我正在尝试创建这个 pokeball 设计器。 我创建了一个开始时设置为“红色”的颜色变量，然后有一个按钮将绿色分配给颜色变量，尽管它似乎没有在 function 之外更新它并且它没有更新颜色window 中的形状。

那么我该如何更新 window 之外的颜色变量呢？

我如何让它在 canvas 上更新？

from tkinter import *

width = 500  # size of window is set
height = 500

colour = 'red'  # colour is initially set to red


def colourchange():
    colour = 'green'
    window.update()


window = Tk()  # creates window
canvas = Canvas(window, width=width, height=height)  # creates canvas
canvas.create_arc(10, 10, width - 10, height - 10, fill=colour, style=PIESLICE, extent=180, width=10)  # creates top shell of pokeball
canvas.create_arc(10, 10, width - 10, height - 10, fill='white', style=PIESLICE, extent=180, width=10, start=180) # creates bottom shell of pokeball

colourButton = Button(window, text='Switch Colour', command=colourchange) # creates button to switch colour of pokeball
colourButton.pack() 

canvas.pack()
window.mainloop()

Answer 1

如果要更改颜色，则需要像创建它时那样配置它。 您不需要在此处使用update()方法。 你可以做这样的事情。

from tkinter import *

width = 500  # size of window is set
height = 500

colour = 'red'  # colour is initially set to red


def colourchange():
    colour = 'green'
    canvas.create_arc(10, 10, width - 10, height - 10, fill=colour, style=PIESLICE, extent=180, width=10)


window = Tk()  # creates window
canvas = Canvas(window, width=width, height=height)  # creates canvas
canvas.create_arc(10, 10, width - 10, height - 10, fill=colour, style=PIESLICE, extent=180, width=10)  # creates top shell of pokeball
canvas.create_arc(10, 10, width - 10, height - 10, fill='white', style=PIESLICE, extent=180, width=10, start=180) # creates bottom shell of pokeball

colourButton = Button(window, text='Switch Colour', command=colourchange) # creates button to switch colour of pokeball
colourButton.pack() 

canvas.pack()
window.mainloop()

Answer 2

您不能以这种方式在函数中更改全局变量colour 。 您的代码在 function 内创建了一个新的局部变量颜色。 如果要使用 function 更改颜色，请添加global关键字

def colourchange():
    global colour
    colour = 'green'
    window.update()

Answer 3

def colourchange():
    global colour
    colour = 'green'
    window.update()

您需要使用 global 关键字来访问外部变量