Tkinter label not executing

Question

I am writing an application using the tkinter module in Python. The section of code I am having trouble with is:

def sceneChange():    
    global num
    num = num + 1
    currentScene = scenes[num]
    global label
    label.destroy()
    label = tk.Label(window, image = currentScene)
    label.pack()
    time1 = dt.datetime.utcnow().minute + dt.datetime.utcnow().second / 60 
    testTime = time1 + 4.44 / 60 # ~5 secs in the future
    while dt.datetime.utcnow().minute + dt.datetime.utcnow().second / 60 < testTime: 
        pass
    label.destroy()
    num = num + 1
    currentScene = scenes[num]
    label = tk.Label(window, image = currentScene)
    label.pack()

Which is used in:

b = tk.Button(label, text = "Start", command = sceneChange, height = 1, width = 10)
b.place(x = 440, y = 48)

The label.pack command before the while loop is not showing in my window. I am trying to make it display for 5 seconds then switch the image to something else. But, it isn't. All help would be appreciated. If I have done something wrong in the formatting of my question, please let me know so I can improve it :). The whole code is below:

import tkinter as tk
import datetime as dt

window = tk.Tk()
window.title("Game")
scenes = [tk.PhotoImage(file = "TitleScreen.gif"), tk.PhotoImage(file = "ControlsScreen.gif"), tk.PhotoImage(file = "game.gif")]
num = 0
currentScene = scenes[num]
label = tk.Label(window, image = currentScene)


def sceneChange():
    global num
    num = num + 1
    currentScene = scenes[num]
    global label
    label.destroy()
    label = tk.Label(window, image = currentScene)
    label.pack()
    time1 = dt.datetime.utcnow().minute + dt.datetime.utcnow().second / 60 # current time
    testTime = time1 + 4.44 / 60 # ~5 secs in the future
    while dt.datetime.utcnow().minute + dt.datetime.utcnow().second / 60 < testTime: 
        pass
    label.destroy()
    num = num + 1
    currentScene = scenes[num]
    label = tk.Label(window, image = currentScene)
    label.pack()


label.pack()
b = tk.Button(label, text = "Start", command = sceneChange, height = 1, width = 10)
b.place(x = 440, y = 48)
b1 = tk.Button(label, text = "Quit", command = exit, height = 1, width = 10)
b1.place(x = 440, y = 78)

label.mainloop()

Jake you have to `after()` instead of while loop, if you use while loop it'll hangs till the loop is done so the first image won't show up anyway. See this post https://stackoverflow.com/questions/25753632/tkinter-how-to-use-after-method — Saad, Apr 19 '19 at 08:24
@Saad Could you please put your comment as an answer so I can accept it, as it did work — Jake, Apr 19 '19 at 09:48

score 0 · Accepted Answer · answered Apr 19 '19 at 10:32

You should use after() function instead of while loop because using while loop causes the window to freeze until the loop ends.

If you want to know how to use `after()`

Go to this post

Now, How you can achieve a picture to display for 5 sec?

Here is an example.

from tkinter import *

root = Tk()

root.geometry("250x250")

Img1 = PhotoImage(file="img1.png")     # Image 1
Img2 = PhotoImage(file="img2.png")      # Image 2

L = Label(root, image=Img1)
L.pack()

# The image will change in 5000ms ( 5secs )
root.after( 5000, lambda: L.config(image=Img2) )

root.mainloop()

Tkinter label not executing

1 Answers1

If you want to know how to use after()

Now, How you can achieve a picture to display for 5 sec?

If you want to know how to use `after()`