有什么方法可以在 Python tkinter canvas 中打印“更改”变量？

Question

I've got some variable in while loop:

import pyautogui as py

while True:
   x, y = py.position()

Is there any way how to print these variables in tkinter window - in for example label, even when it is while loop? Or is there any way how to print "changing" variable in tkinter label?

Answer 1

In tkinter you should rather use root.after(milliseconds, function_name) instead of while -loop because while -loop will block mainloop and tkinter will freeze. Using after it will send information to mainloop and it will run it after milliseconds and it will have also time to get mouse/key events from system, send them to widgets and update/redraw all widgets in window so it will not freeze.

import tkinter as tk
import pyautogui as py

# --- functions ---

def update_label():
    x, y = py.position()
    label['text'] = f'{x}, {y}' 
    root.after(25, update_label)  # run again after 25ms
    
# --- main ---

root = tk.Tk()

label = tk.Label(root)  # with empty text
label.pack(padx=5, pady=5)

#update_label()  # run first time at once
root.after(25, update_label)  # run first time after 25ms

root.mainloop()   

---

If you really have to use while -loop then you will have to use root.update() to force mainloop to update widgets in window.

import tkinter as tk
import pyautogui as py

# --- main ---

root = tk.Tk()

label = tk.Label(root)  # with empty text
label.pack(padx=5, pady=5)

while True:
    x, y = py.position()
    label['text'] = f'{x}, {y}'
    root.update()