Continuous tkinter text update in loop

Question

I have created a script which constantly screenshots and finds elements on the screen, and I want to use tkinter or a similar framework to overlay text on the screen. The main script runs in a while loop and checks every x seconds, and I want the tkinter window to also update ever x seconds until the script is closed.

import tkinter as tk
from pynput import keyboard

def superimpose_text(text):
    color = "black" if isinstance(text, str) else 'green' if text < 10 else 'yellow' if text < 15 else 'red'
    label = tk.Label(root, text=text, font=('Times New Roman', '50'), fg=color, bg='white')
    label.lift()
    root.geometry("+1400+600")
    root.wm_attributes("-topmost", True)
    root.wm_attributes("-disabled", True)
    root.wm_attributes("-transparentcolor", "white")
    label.pack()

    listener = keyboard.Listener(on_press=lambda event: root.destroy())
    listener.start()

while True:
    root = tk.Tk()
    text = screenshot_info()
    superimpose_text(text)
    root.mainloop()

Currently I'm using a listener to destroy the label at any keypress, as that's the only way I can get It to ever update the text, but this isn't working. How do i make it continuously update every time the while loop runs?

text = screenshot_info() NameError: name 'screenshot_info' is not defined — toyota Supra, Jun 09 '23 at 11:57
`while` loops and tkinter tend not to mix well, particularly if there's any slow-running or blocking process inside the loop. This can lead to slow or stuck UI. You should look into tkinter's `after()` method. I'll link a suitable answer here in a minute... — JRiggles, Jun 09 '23 at 11:59
Does this answer your question? [tkinter: how to use after method](https://stackoverflow.com/questions/25753632/tkinter-how-to-use-after-method) — JRiggles, Jun 09 '23 at 12:01
@toyotaSupra Yeah the screenshot_info isnt important for the question, replace "hello world" — Tobias Christensen, Jun 09 '23 at 12:02
@JRiggles i did look into the .after method, but I cant quite figure out how to set it up — Tobias Christensen, Jun 09 '23 at 12:03
@Tobias Christensen. It worked for me. `text = "screenshot_info()"`. But is freezing can't move window. — toyota Supra, Jun 09 '23 at 12:05
@toyotaSupra yes it adds text, but if you click any buttons it breaks — Tobias Christensen, Jun 09 '23 at 12:06
@toyotaSupra yes its supposed to write it again forever, that's what the while loop is for, and then the screenshot_info is supposed to give me new text each click — Tobias Christensen, Jun 09 '23 at 12:09
@JRiggles. label = tk.Label(root, text=text, font=('Times New Roman', '50'), fg=color, bg='white') NameError: name 'root' is not defined — toyota Supra, Jun 09 '23 at 12:11
@toyotaSupra that's because OP declared root in a weird place — JRiggles, Jun 09 '23 at 12:12
We don't offer a code writing service or trying to replace the official documentation here. Please show a minimum of effort and ask for a specific programming issue here. — Thingamabobs, Jun 09 '23 at 12:33

JRiggles · Accepted Answer · 2023-06-09T13:40:10.100

1

Take the declaration of root = tk.Tk() and root.mainloop() out of the while loop - tkinter runs its own GUI event loop anyway, so it's handled for you. Then, wrap the calls to text = screenshot_info() and superimpose_text(text) into a function (ex. def update_text()) that calls itself again using after(), e.g. after(100, update_text). To start the updates, just call update_text() as normal.

import tkinter as tk


# instantiate Tk and set the window properties here
root = tk.Tk()
root.geometry("+1400+600")
root.wm_attributes("-topmost", True)
root.wm_attributes("-disabled", True)
root.wm_attributes("-transparentcolor", "white")

label = tk.Label(
    root, 
    text='', 
    font=('Times New Roman', '50'),
    fg='black', 
    bg='white',
)
label.pack()


def superimpose_text(text):
    color = "black" if isinstance(text, str) else 'green' if text < 10 else 'yellow' if text < 15 else 'red'
    # update the label
    label.config(text=text, fg=color)


def update_text():
    text = screenshot_info()
    superimpose_text(text)
    root.after(100, update_text)  # have this func call itself again every 100mS


update_text()  # start the update loop
root.mainloop()

There are some issues with how you're setting color, but I'm going to leave that to you.

edited Jun 09 '23 at 13:40

answered Jun 09 '23 at 12:12

JRiggles

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The code still stops after i press a button, it doesn't continue to run – Tobias Christensen Jun 09 '23 at 12:14
It doesn't work, man – toyota Supra Jun 09 '23 at 12:15
You're calling `root.destroy()` on keyboard presses - what did you expect to happen? – JRiggles Jun 09 '23 at 12:16
line 14, in listener = keyboard.Listener(on_press=lambda event: root.destroy()) ^^^^^^^^^^^^^^ – toyota Supra Jun 09 '23 at 12:17
Also, setting `root` properties like `geometry` shouldn't be handled inside a function like that if you don't actually need to set/update them more than once. I'll edit my answer to reflect this. – JRiggles Jun 09 '23 at 12:18
And another important point regarding the keybinding: tkinter has built-in functionality for this, e.g.: `root.bind('' , lambda _event: callback_function())`, which is to say you probably don't need `pynput` – JRiggles Jun 09 '23 at 12:24
So I read through your question again and it sounds to me like you don't need the keypress event at all if it was just a workaround for getting the text to update. I'm going to remove that code from this answer. – JRiggles Jun 09 '23 at 12:29
Yeah the keypress was just a means to make it "work", and the solution you have made is close, but it doesn't overwrite the current text, it makes a new text block, can it be made to overwrite the old text? – Tobias Christensen Jun 09 '23 at 13:34
Should be fixed now. The idea is to create the `Label` once, and then update it as needed – JRiggles Jun 09 '23 at 13:41
Thank you, this is so good! The one issue with it is that the tkinter window is visible for this version, it wasn't in my original version, but I cannot even see why its different. Thanks though, will marked as solved – Tobias Christensen Jun 09 '23 at 14:15
You may need to set the color of your `root` window to match your `-transparentcolor`, i.e. `'white'` – JRiggles Jun 09 '23 at 14:25
That does remove the background of the tkinter window but not the border of the window with the topbar – Tobias Christensen Jun 09 '23 at 14:36
i added "label.master.overrideredirect(True)" which works! – Tobias Christensen Jun 09 '23 at 14:39
You can just use `root.overrideredirect(True)` since `root` is the `master` of your `label` – JRiggles Jun 09 '23 at 15:03

Continuous tkinter text update in loop

1 Answers1