使用 Tkinter 按钮停止迭代函数

Question

I have created a GUI with a "stop" button. When the GUI is ran, another module is called that contains a while loop for a background function. The stop button would be used to pass a variable to the loop to stop it. However, when the module containing the loop is called the GUI freezes. I have considered using the library "threading" but cannot find any tkinter specific content. Any advice or small example of how you would create the code would help a lot.

Answer 1

This is just a sample program to illustrate how to kill a running thread.

    import threading 
    import time 

    def run(): 
        while True: 
            print('thread running') 
            global stop_threads 
            if stop_threads: 
                break



    if __name__=="__main__":
        stop_threads = False
        t1 = threading.Thread(target = run) ##background loop
        t1.start() 
        time.sleep(1) 
        #while clicking on the button in GUI kill the thread like this
        stop_threads = True 
        t1.join() 
        print('thread killed')

Answer 2

Here is a basic GUI with 2 buttons that can start and stop a thread which increments a variable count .

I let you try it :

import tkinter as tk
import threading
import time

class GUI(tk.Tk):
    def __init__(self):
        tk.Tk.__init__(self)
        self.title("test")
        self.button_start = tk.Button(self, text="Start", command=self.start_thread)
        self.button_start.pack()
        self.button_stop = tk.Button(self, text="Stop", command=self.stop_thread)
        self.button_stop.pack()
        self.count = 0
        self.continue_thread = True


    def start_thread(self):
        self.count = 0
        self.continue_thread = True

        self.t1 = threading.Thread(target = self.counter)
        self.t1.daemon = True # With this parameter, the thread functions stops when you stop the main program
        self.t1.start()

    def stop_thread(self):
        self.continue_thread = False
        self.t1.join()

    def counter (self):
        while self.continue_thread:
            print("i =", self.count)
            self.count += 1
            time.sleep(1)

if __name__ == "__main__":
    app = GUI()
    app.mainloop()