无法弄清楚在 tkinter 中制作计时器

Question

I haven't added much to my code so far but what it is supposed to do is decrement variable time_1 by 1 every second, it does not do this and instead it turns to 0 almost immediately. What am I doing wrong?

import tkinter as tk
import threading
from tkinter import ttk

root = tk.Tk()
root.title("Chess Timer")
root.minsize(250,250)

time_1 = 60.0
time_2 = 60.0

timer_1 = ttk.Label(root, text=time_1)
timer_1.grid(column=1, row=0)
timer_2 = ttk.Label(root, text=time_2)
timer_2.grid(column=2, row=0)

def update():
    timer_1.config(text=time_1)
    timer_2.config(text=time_2)

while time_1 and time_2 > 0:
    time_1 -= 1
    threading.Timer(1.0,update).start()

root.mainloop()

I'm new to python, any help is appreciated!

Answer 1

The problem here is in the while loop. The call to threading.Timer(1.0, update).start() does not make the loop wait one second; it makes the calls to update wait one second.. Thus, 60 1-second timers are set almost immediately, and all update the labels at about the same time. The while loop, meanwhile, subtracts both time_1 down to zero in almost an instant, since it's not being hindered by the timer.

For something like this, you don't need to use the threading module. You can just use the root.after() function to call your function after a set number of milliseconds. Here is what your code would look like using root.after() :

import tkinter as tk
from tkinter import ttk

root = tk.Tk()
root.title("Chess Timer")
root.minsize(250,250)

time_1 = 60.0
time_2 = 60.0

timer_1 = ttk.Label(root, text=time_1)
timer_1.grid(column=1, row=0)
timer_2 = ttk.Label(root, text=time_2)
timer_2.grid(column=2, row=0)

def update():
    global time_1, timer_1, root

    time_1 -= 1
    timer_1.config(text=time_1)
    
    root.after(1000, update)

update()
root.mainloop()