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pythonpython-3.xtkinterbuttonwhile-loop

Tkinter - Loop Start/Stop with button - threading option


I have a problem with the termination of the while loop which is started via the thread option.

The stop variable has the values True and False. Should I start the Stop option via a thread?

The complete program starts, a loop is started that prints the word TEST every second, clicking the STOP button I get nothing!

I even think my stop is disabled when the loop is in progress!

import tkinter as tk
import threading
import time

class App(tk.Tk):
   
  def __init__(self):
    super().__init__()
 
    global stop
    stop = False
     
    # If the STOP button is pressed then terminate the loop
    def button_stop_command():
        global stop
        stop = True
    
   # Start loop
    def button_start_command():
        global stop
        stop = False
        
        while stop == False:
            print("TEST")
            time.sleep(1)
    
    # Button starter with thread
    def button_starter():
      t = threading.Thread(target=button_start_command)
      t.start()
           
    # self windows size
    window_width = 1024
    window_height = 600

    # get the screen dimension
    screen_width = self.winfo_screenwidth()
    screen_height = self.winfo_screenheight()

    # find the center point
    center_x = int(screen_width/2 - window_width / 2)
    center_y = int(screen_height/2 - window_height / 2)

    # set the position of the window to the center of the screen
    self.geometry(f'{window_width}x{window_height}+{center_x}+{center_y}')
    
    # Resize main window xy, on/off,  0 or 1 .
    self.resizable(0, 0)
    
    # Main window on top of stack.
    self.attributes('-topmost', 1) 
        
    # Windows transparency.
    self.attributes('-alpha', 1) 
                 
    # Button START
#     self.button = tk.Button(self, text='START', width = 20, height = 10, command = self.button_clicked)
    self.button = tk.Button(self, text='START', width = 20, height = 10, command = button_start_command)
    self.button.place(x = 600, y = 350)
    
    # Button STOP
#     self.button = tk.Button(self, text='START', width = 20, height = 10, command = self.button_clicked)
    self.button_stop = tk.Button(self, text='STOP', width = 20, height = 10, command = button_stop_command)
    self.button_stop.place(x = 800, y = 350)
    
         
    

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

Stop loop with STOP button!


Solution

  • Answer to your question "should I start the Stop option via a thread?" is "Yes,I think you should.You've almost done!!" Only change command = button_start_command to command = button_starter and this worked in my envronment!!