How can I schedule updates (f/e, to update a clock) in tkinter?
I'm writing a program with Python's tkinter library.
My major problem is that I don't know how to create a timer or a clock lik开发者_StackOverflowe hh:mm:ss
.
I need it to update itself (that's what I don't know how to do); when I use time.sleep()
in a loop the whole GUI freezes.
Tkinter root windows have a method called after
which can be used to schedule a function to be called after a given period of time. If that function itself calls after
you've set up an automatically recurring event.
Here is a working example:
# for python 3.x use 'tkinter' rather than 'Tkinter'
import Tkinter as tk
import time
class App():
def __init__(self):
self.root = tk.Tk()
self.label = tk.Label(text="")
self.label.pack()
self.update_clock()
self.root.mainloop()
def update_clock(self):
now = time.strftime("%H:%M:%S")
self.label.configure(text=now)
self.root.after(1000, self.update_clock)
app=App()
Bear in mind that after
doesn't guarantee the function will run exactly on time. It only schedules the job to be run after a given amount of time. It the app is busy there may be a delay before it is called since Tkinter is single-threaded. The delay is typically measured in microseconds.
Python3 clock example using the frame.after() rather than the top level application. Also shows updating the label with a StringVar()
#!/usr/bin/env python3
# Display UTC.
# started with https://docs.python.org/3.4/library/tkinter.html#module-tkinter
import tkinter as tk
import time
def current_iso8601():
"""Get current date and time in ISO8601"""
# https://en.wikipedia.org/wiki/ISO_8601
# https://xkcd.com/1179/
return time.strftime("%Y%m%dT%H%M%SZ", time.gmtime())
class Application(tk.Frame):
def __init__(self, master=None):
tk.Frame.__init__(self, master)
self.pack()
self.createWidgets()
def createWidgets(self):
self.now = tk.StringVar()
self.time = tk.Label(self, font=('Helvetica', 24))
self.time.pack(side="top")
self.time["textvariable"] = self.now
self.QUIT = tk.Button(self, text="QUIT", fg="red",
command=root.destroy)
self.QUIT.pack(side="bottom")
# initial time display
self.onUpdate()
def onUpdate(self):
# update displayed time
self.now.set(current_iso8601())
# schedule timer to call myself after 1 second
self.after(1000, self.onUpdate)
root = tk.Tk()
app = Application(master=root)
root.mainloop()
from tkinter import *
import time
tk=Tk()
def clock():
t=time.strftime('%I:%M:%S',time.localtime())
if t!='':
label1.config(text=t,font='times 25')
tk.after(100,clock)
label1=Label(tk,justify='center')
label1.pack()
clock()
tk.mainloop()
You should call .after_idle(callback)
before the mainloop and .after(ms, callback)
at the end of the callback
function.
Example:
import tkinter as tk
import time
def refresh_clock():
clock_label.config(
text=time.strftime("%H:%M:%S", time.localtime())
)
root.after(1000, refresh_clock) # <--
root = tk.Tk()
clock_label = tk.Label(root, font="Times 25", justify="center")
clock_label.pack()
root.after_idle(refresh_clock) # <--
root.mainloop()
I have a simple answer to this problem. I created a thread to update the time. In the thread i run a while loop which gets the time and update it. Check the below code and do not forget to mark it as right answer.
from tkinter import *
from tkinter import *
import _thread
import time
def update():
while True:
t=time.strftime('%I:%M:%S',time.localtime())
time_label['text'] = t
win = Tk()
win.geometry('200x200')
time_label = Label(win, text='0:0:0', font=('',15))
time_label.pack()
_thread.start_new_thread(update,())
win.mainloop()
I just created a simple timer using the MVP pattern (however it may be overkill for that simple project). It has quit, start/pause and a stop button. Time is displayed in HH:MM:SS format. Time counting is implemented using a thread that is running several times a second and the difference between the time the timer has started and the current time.
Source code on github
from tkinter import *
from tkinter import messagebox
root = Tk()
root.geometry("400x400")
root.resizable(0, 0)
root.title("Timer")
seconds = 21
def timer():
global seconds
if seconds > 0:
seconds = seconds - 1
mins = seconds // 60
m = str(mins)
if mins < 10:
m = '0' + str(mins)
se = seconds - (mins * 60)
s = str(se)
if se < 10:
s = '0' + str(se)
time.set(m + ':' + s)
timer_display.config(textvariable=time)
# call this function again in 1,000 milliseconds
root.after(1000, timer)
elif seconds == 0:
messagebox.showinfo('Message', 'Time is completed')
root.quit()
frames = Frame(root, width=500, height=500)
frames.pack()
time = StringVar()
timer_display = Label(root, font=('Trebuchet MS', 30, 'bold'))
timer_display.place(x=145, y=100)
timer() # start the timer
root.mainloop()
You can emulate time.sleep
with tksleep and call the function after a given amount of time. This may adds readability to your code, but has its limitations:
def tick():
while True:
clock.configure(text=time.strftime("%H:%M:%S"))
tksleep(0.25) #sleep for 0.25 seconds
root = tk.Tk()
clock = tk.Label(root,text='5')
clock.pack(fill=tk.BOTH,expand=True)
tick()
root.mainloop()
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