如何设置 tkinter textvariable 在单独的线程上运行？

Question

尝试更新在具有“main”函数变量的线程上运行的 tkinter“textvariable”。我实现了一个基于线程的解决方案，因此 tkinter 主循环之后的代码可以运行：https://stackoverflow.com/a/1835036/15409926。

请分享我如何解决此错误。如果这不是更新“textvariable”的最简单方法，请分享替代方法。

代码：

from tkinter import *
from threading import Thread

class GUI(Thread):
    def __init__(self):
        Thread.__init__(self)
        self.start()

    def run(self):
        self.root = Tk()
        self.var = StringVar()
        self.var.set("Initiated")

        screen_width = self.root.winfo_screenwidth()
        screen_height = self.root.winfo_screenheight()

        width = screen_width*.12
        height = screen_height
        x = screen_width - width
        y = screen_height*.025

        self.root.geometry('%dx%d+%d+%d' % (width, height, x, y))

        label = Label(self.root, textvariable= self.var)
        label.pack()

        self.root.mainloop()

gui = GUI()

def main():
    for i in range(1000):
        gui.var.set(f'Current Iteration: {i}')

if __name__ == '__main__':
    main()

窗口不更新： Tkinter window displays initial 'textvariable'

错误：

Traceback (most recent call last):
  File "test.py", line 36, in <module>
    main()
  File "test.py", line 33, in main
    gui.var.set(f'Current Iteration: {i}')
AttributeError: 'GUI' object has no attribute 'var'

Answer 1

大多数 GUI 不喜欢在单独的线程中更改小部件中的值。

您应该使用queue 向线程发送值，它应该使用root.after(time, function) 定期运行函数，该函数将从队列中获取值并在GUI 中更新值。

import tkinter as tk  # PEP8: `import *` is not preferred
from threading import Thread
import queue
import time  # simulate show program

class GUI(Thread):
    
    def __init__(self, queue):
        super().__init__()
        self.queue = queue
        self.start()

    def run(self):
        self.root = tk.Tk()
        self.var = tk.StringVar()
        self.var.set("Initiated")

        screen_width = self.root.winfo_screenwidth()
        screen_height = self.root.winfo_screenheight()

        width = int(screen_width*.12)
        height = int(screen_height)
        x = int(screen_width - width)
        y = int(screen_height*.025)

        self.root.geometry(f'{width}x{height}+{x}+{y}')

        label = tk.Label(self.root, textvariable=self.var)
        label.pack()
 
        # run first time after 100ms (0.1 second)
        self.root.after(100, self.check_queue)

        self.root.mainloop()

    def check_queue(self):
        #if not self.queue.empty():
        while not self.queue.empty():
            i = self.queue.get()
            self.var.set(f'Current Iteration: {i}')

        # run again after 100ms (0.1 second)
        self.root.after(100, self.check_queue)
        
def main():
    q = queue.Queue()
    gui = GUI(q)

    for i in range(1000):
        q.put(i)
        # simulate show program
        time.sleep(0.5)


if __name__ == '__main__':
    main()

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PEP 8 -- Style Guide for Python Code