Progressbar Starts After Print Statements

Why is the progressbar starting after the print-commands? I want to start the progressbar first. And wenn the 2nd print command ('After the sleep statement') was excecuted, I want

Solution 1:

@Kaz's answer without the need for the button:

import threading
import time

from tkinter import Tk, Button
from tkinter.ttk import Progressbar


# root window
root = Tk()
root.geometry('300x120')
root.title('Progressbar Demo')

# progressbar
pb = Progressbar(root, orient="horizontal", length=280)
pb.grid(column=0, row=0, columnspan=2, padx=10, pady=20)

defstatement():
    global stop_the_progressbar
    print("Before the sleep statement")
    time.sleep(5)
    print("After the sleep statement")
    stop_the_progressbar = Truedeftkinter_loop():
    if stop_the_progressbar:
        pb.stop()
    else:
        root.after(100, tkinter_loop)

# Start the progressbar
pb.start()
threading.Thread(target=statement, daemon=True).start()
stop_the_progressbar = False
tkinter_loop()

root.mainloop()

It uses a .after loop to check if the progressbar should be stopped. Look at this for more details on how .after works. Also please note that you shouldn't call any tkinter methods from the new thread.

This example doesn't run well on IDLE because of a bug in IDLE. The text "Before the sleep statement" will be printed after the thread stops but it actually runs at the correct time.

Solution 2:

The progress bar and all graphical elements of tkinter are launched from main loop (root.mainloop()). So, sleeping is done before the main loop. If you want so, you should implement spleeping IN main loop.

Furthermore, for a non-instantaneous processing, it's recommended to use a separate thread (e.g. with threading.Tread) to avoid blocking the GUI thread.

You can do something like this :

import threading
import time

from tkinter import Tk, Button
from tkinter.ttk import Progressbar


# root window
root = Tk()
root.geometry('300x120')
root.title('Progressbar Demo')

root.grid()

# progressbar
pb = Progressbar(root, orient='horizontal', mode='indeterminate', length=280)
# place the progressbar
pb.grid(column=0, row=0, columnspan=2, padx=10, pady=20)

defstatement():
    pb.start()
    print("Before the sleep statement")
    time.sleep(5)
    print("After the sleep statement")
    pb.stop()

button = Button(root, text="Start", command=lambda: threading.Thread(target=statement).start())
button.grid(column=0, row=1)

root.mainloop()