Python: Is it possible to create an tkinter label which has a dynamic string when a function is running in background?

Question

I have created a tkinter GUI for my python script. When I run the script, I want a dynamic string in one of the Label widgets on the GUI window, which will display:

Answer 1

I wrote two simple scripts to help demonstrate how to do what you want. The first is using the label:

import tkinter as tk

root = tk.Tk()

status = tk.Label(root, text="Working")
status.grid()

def update_status():

    # Get the current message
    current_status = status["text"]

    # If the message is "Working...", start over with "Working"
    if current_status.endswith("..."): current_status = "Working"

    # If not, then just add a "." on the end
    else: current_status += "."

    # Update the message
    status["text"] = current_status

    # After 1 second, update the status
    root.after(1000, update_status)

# Launch the status message after 1 millisecond (when the window is loaded)
root.after(1, update_status)

root.mainloop()

The next one is using a progressbar:

import tkinter as tk

# You will need the ttk module for this
from tkinter import ttk

def update_status(step):

    # Step here is how much to increment the progressbar by.
    # It is in relation to the progressbar's length.
    # Since I made the length 100 and I am increasing by 10 each time,
    # there will be 10 times it increases before it restarts
    progress.step(step)

    # You can call 'update_status' whenever you want in your script
    # to increase the progressbar by whatever amount you want.
    root.after(1000, lambda: update_status(10))

root = tk.Tk()

progress = ttk.Progressbar(root, length=100)
progress.pack()

progress.after(1, lambda: update_status(10))

root.mainloop()

Note however that I couldn't do too much with the progressbar script because progressbars are a little tricky and need to be customized to your script exactly. I just wrote it to maybe shed a little light on the subject. The main part of my answer though is the label script.

Answer 2

Yes, it is possible. There are two ways to do it:

1. Whenever you want to update the label from your code you can call the_widget.configure(the_text). This will change the text of the label.

2. You can create an instance of a tkinter.StringVar, and assign it to the textvariable attribute of a label. Whenever you change the value of the variable (via the_variable.set(the_text), the label will automatically update.

Note that for either of these to work, the event loop needs to be able to process events (ie: you won't see anything if your function takes a long time to run and you never call update_idletasks or re-enter the event loop).