Creating a loading screen in tkinter

Question

Is there any way to create a loading screen in tkinter?

Here's the code:

from tkinter import *

root = Tk()

text = Text(root , width = 65 , height = 20 , font = "consolas 14")
text.pack()

text.insert('1.0' , "hello\n"*5000000)

mainloop()

Here, the main window takes some time to pop up, so I would like to create a temporary window that tells the user that some process is going on.

To do this, I did something like this:

from tkinter import *

root = Tk()

temp_win = Toplevel()
message_label = Label(temp_win , text = "Loading.. Please wait")
message_label.pack()

text = Text(root , width = 65 , height = 20 , font = "consolas 14")
text.pack()

text.insert('1.0' , "hello\n"*5000000)

mainloop()

But here, both the windows only pop up only when the mainloop function is called, which is of no use.

My goal is to show the temporary window before the main window pops up.

Is there any way to achieve this in tkinter?

It would be great if anyone could help me out.

Answer 1

Let the tkinter be in main code, but make a function for the splash screen, so its like:

import threading
from tkinter import *

started = False
def pop():
    new = Tk()

    l = Label(new,text='Loading')
    l.pack()

    new.protocol('WM_DELETE_WINDOW',lambda: new.destroy() if started else False) # Close the window only if main window has shown up
    new.mainloop()

threading.Thread(target=pop).start() # Use this before the heavy process starts

root = Tk()

text = Text(root , width = 65 , height = 20 , font = "consolas 14")
text.pack()

text.insert('1.0' , "hello\n"*5000000) # If you want to see real delay use time.sleep(5)

started = True
root.mainloop()

This way there is no relation between the first two instances of Tk directly, using a Toplevel would require a Tk instance to be made first.

Flag started is used just to ensure that the splash screen cannot be closed before the main window pops up.

Answer 2

tkinter doesn't allow you to call it from multiple threads (it might crash without any errors). This means that you can't do any GUI stuff in threads other than the main one/where you create your Tk(). Also there are some bugs with how _tkinter communicates with tcl. Keeping that in mind this is what I have:

from time import sleep
import tkinter as tk
from threading import Thread

def non_gui_stuff():
    # We are going to do some work
    sleep(3)


t = Thread(target=non_gui_stuff, daemon=True)
t.start()

root = tk.Tk()
# Hide the main window until the non-GUI stuff is done
root.withdraw()

# Create the loading screen
loading_screen = tk.Toplevel(root)
loading_label = tk.Label(loading_screen, text="Loading")
loading_label.pack()

# While the thread is alive
while t.is_alive():
    # Update the root so it will keep responding
    root.update()
print("Non-GUI thread is done")

loading_screen.destroy()
# Show the main window
root.deiconify()
root.focus_force()

root.mainloop()

Answer 3

I believe you could do this with threading.

import threading
from tkinter import *

root = Tk()

def loading_screen():
    temp_win = Toplevel()
    message_label = Label(temp_win , text = "Loading.. Please wait")
    message_label.pack()

def main():
    text = Text(root , width = 65 , height = 20 , font = "consolas 14")
    text.pack()

    text.insert('1.0' , "hello\n"*5000000)

a = threading.Thread(target=loading_screen)
b = threading.Thread(target=main)
a.start()
b.start()
mainloop()