全局變量不適用於線程 - Python

Question

我希望能夠在線程中更改 Tkinter 框架的背景顏色，該框架是在單獨的函數中聲明的。 運行以下代碼時收到以下錯誤。

錯誤： NameError: name 'mainScreen' is not defined

代碼：

import tkinter as tk
from tkinter import ttk
from multiprocessing import Process


def main():
    global mainScreen
    
    root = tk.Tk()
    root.geometry('1040x540+50+50')

    mainScreen = tk.Frame(root, width = 1040, height = 540)
    mainScreen.place(x=0, y=0)

    root.mainloop()


def test(): # This function is in a thread as it will be run as a loop.
    while True:
        mainScreen.configure(bg='red')

if __name__ == '__main__':
    p2 = Process(target = test)
    p2.start()
    main()

任何幫助表示贊賞。

Answer 1

你可以用這個替換你的整個代碼：

import tkinter as tk

def main():
    global mainScreen

    root = tk.Tk()
    root.geometry('1040x540+50+50')

    mainScreen = tk.Frame(root, width=1040, height=540)
    mainScreen.place(x=0, y=0)
    mainScreen.configure(bg='red')
    root.mainloop()


if __name__ == '__main__':
    main()

如果你想改變顏色，你可以這樣做：

import time
import tkinter as tk
from threading import Thread


def test(mainScreen):  # This function is in a thread as it will be run as a loop.
    while True:
        try:
            time.sleep(1)
            mainScreen.configure(bg='red')
            time.sleep(1)
            mainScreen.configure(bg='blue')
        except RuntimeError:
            break


if __name__ == '__main__':
    root = tk.Tk()
    root.geometry('1040x540+50+50')

    mainScreen = tk.Frame(root, width=1040, height=540)
    mainScreen.place(x=0, y=0)
    p2 = Thread(target=test, args=(mainScreen,))
    p2.start()

    root.mainloop()