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Tkinter doesn't print on window

import tkinter as tk
def quit():
global root
root.quit()
def prnt():
global usrinpt
lbl = tk.Label(text = usrinpt )
lbl.pack()
root = tk.Tk()
usrentr = tk.Entry()
usrinpt = str(usrentr.get())
usrentr.pack()
extbt = tk.Button(command=quit,text = 'Exit')
extbt.pack()
lblbt = tk.Button(command = prnt, text = 'Label')
lblbt.pack()
root.mainloop()
When I hit the Label button it just extends the window and doesn't print anything.
Thanks for the help!

You're adding the entry box then instantly trying to get the contents in the subsequent line. You should instead add a "submit" button that has the command set to star(usrentr.get())

only last modification to Label being shown in Python - Tkinter . Why?

I am learning GUI development using Tkinter. I want to show multiple messages on the label which I have stored in a string. I used sleep to view the changes.However only the last message string is shown at execution.
from tkinter import *
import time
master = Tk()
def onClick():
for i in range(0,len(list_of_str)):
w.configure(text=list_of_str[i])
time.sleep(5)
list_of_str = ['first','second','third','fourth','fifth']
w = Label(master, text="Hello, world!")
b = Button(master,text='Click me',command = onClick)
w.pack()
b.pack()
mainloop()
I am a noobie. So thanks for helping !

A simple solution to your problem is to use a combination of the try/except method and using after().
In tkinter sleep() will pause the application instead of providing a timer. For tkinter you want to use the after() method to scheduled an event after a set amount of time instead. The after() method is meant for this exact problem and is what you will always use in tkinter for a delayed event.
In my below example I modified your onClick function to take 1 argument and to use that in our after() method to select the next item in the list after 5 seconds. Note that for the after() method time is done in milliseconds so 5000 is 5 seconds.
from tkinter import *
master = Tk()
def onClick(ndex):
try:
w.configure(text=list_of_str[ndex])
master.after(5000, onClick, ndex+1)
except:
print("End of list")
list_of_str = ['first','second','third','fourth','fifth']
w = Label(master, text="Hello, world!")
b = Button(master,text='Click me',command = lambda: onClick(0))
w.pack()
b.pack()
mainloop()

I think you want this:
from tkinter import *
import time
master = Tk()
global i
i = 0
def onClick():
master.after(1, change)
def change():
global i
if i == len(list_of_str):
pass
else:
w.configure(text=list_of_str[i])
i += 1
master.after(1000, onClick)
list_of_str = ['first','second','third','fourth','fifth']
w = Label(master, text="Hello, world!")
b = Button(master,text='Click me',command = onClick)
w.pack()
b.pack()
mainloop()
time.sleep is a no-no in tkinter. I advise you make your gui in a class and it wil be easier.
example with class:
import tkinter as tk
from tkinter import *
class GUI:
def __init__(self, master):
self.list_of_str = ['first','second','third','fourth','fifth']
self.count = 0
self.master = master
self.w = Label(master, text="Hello, world!")
self.w.pack()
self.b = Button(master,text='Click me',command = self.onClick)
self.b.pack()
def onClick(self, event=None):
if self.count == len(self.list_of_str):
pass
else:
self.w.configure(text=self.list_of_str[self.count])
self.count += 1
self.master.after(1000, self.onClick)
def main():
root = tk.Tk()
app = GUI(root)
root.mainloop()
if __name__ == '__main__':
main()

Label Is Not Shown When Called From Other Tkinter Program

I was writing a program with a start page, and two programs that are called from that start page. Both of the subprograms work by themselves. However, when I put them into my start page, the stopwatch timing label doesn't show up. If you are wondering, I put them into my program by doing:
import program
program.function()
Here is my start page program:
from Tkinter import *
class start_page:
def __init__(self,master):
self.master = master
self.frame = Frame(self.master)
self.countdown = Button(master, text = "Timer", command = self.c).pack()
self.stopwatch_butt = Button(master,text="Stopwatch",command=self.g).pack()
def g(self):
import stopwatch
stopwatch.f()
def c(self):
import timer_prog
timer_prog.timer()
self.master.after_cancel(timer_prog)
def main():
root = Tk()
s = start_page(root)
root.title("Timer Suite: Brian Ton")
root.mainloop()
main()
If I run this program, the timer program works fine, but the stopwatch doesn't show its label, only its buttons. I tried to clear all Tk after functions, and that didn't work, and I also tried to run the stopwatch program first, to no avail.
Here is my stopwatch program:
from Tkinter import *
import datetime
def s():
start.config(state='disabled')
stop.config(state="normal")
reset.config(state='disabled')
Start()
def Start():
if reset['state'] == 'disabled' and stop['state'] == 'normal':
hidden.set(str(int(hidden.get())+1))
root.update()
root.after(1000,Start)
curr = hidden.get()
g.set(str(datetime.timedelta(seconds=int(curr))))
print g.get()
else:
return None
def Stop():
start.config(state='disabled')
stop.config(state='disabled')
reset.config(state="normal")
def Reset():
start.config(state="normal")
stop.config(state="disabled")
reset.config(state='disabled')
hidden.set('0')
g.set(str(datetime.timedelta(seconds=0)))
def f():
global root,frame,master,hidden,g,timelabel,start,stop,reset
root = Tk()
frame = Frame(root)
master = root
hidden = StringVar()
g = StringVar()
hidden.set('0')
timelabel = Label(master,textvariable=g)
g.set(str(datetime.timedelta(seconds=int(0))))
timelabel.grid(row=1,column=2)
start = Button(master,text="Start",command = s,state="normal")
stop = Button(master,text="Stop",command = Stop,state = "disabled")
reset = Button(master,text="Reset",command = Reset,state = "disabled")
start.grid(row=2,column=1)
stop.grid(row=2,column=2)
reset.grid(row=2,column=3)
root.update()
root.mainloop()
And here is my timer program:
from Tkinter import *
import datetime
def get_seconds(h,m,s):
hr_sec = h * 3600
m_sec = m * 60
return hr_sec+m_sec+s
def timerstartstop():
hours = hour_entry.get()
minutes = minute_entry.get()
sec = second_entry.get()
if hours == "":
hours = 0
hour_entry.insert(0,"0")
if minutes == "":
minutes = 0
minute_entry.insert(0,"0")
if sec == "":
sec = 0
second_entry.insert(0,"0")
c = get_seconds(int(hours), int(minutes), int(sec))
global s
s = StringVar(master)
s.set(c)
if startstop['text'] == 'Stop':
global curr
curr = shown
s.set(-1)
if startstop['text'] == 'Reset':
startstop.config(text="Start")
s.set(c)
root.update()
shown.set(str(datetime.timedelta(seconds=int(s.get()))))
return None
countdown()
import winsound
def countdown():
startstop.config(text="Stop")
global shown
good = True
shown = StringVar(master)
shown.set(str(datetime.timedelta(seconds=int(s.get()))))
L = Label(master,textvariable=shown).grid(row=1,column=2)
if int(s.get()) == 0:
startstop.config(text="Reset")
while startstop['text'] != "Start":
root.update()
winsound.Beep(500,500)
elif int(s.get()) < 0:
good = False
shown.set(curr.get())
startstop.config(text="Reset")
else:
if good:
s.set(str(int(s.get())-1))
root.after(1000,countdown)
def ex():
root.after_cancel(countdown)
root.destroy()
def timer():
global root
global master
global frame
root = Tk()
master = root
frame = Frame(master)
global hour_entry
hour_entry = Entry(master,width=3)
hour_entry.grid(row=0,column=0)
colon_l = Label(master,text=':').grid(row=0,column=1)
global minute_entry
minute_entry = Entry(master,width=2)
minute_entry.grid(row=0,column=2)
colon_l2 = Label(master,text=':').grid(row=0,column=3)
global second_entry
second_entry = Entry(master,width=2)
second_entry.grid(row=0,column=4)
global startstop
startstop = Button(master,text="Start",command=timerstartstop)
e = Button(master,text="Exit",command=ex).grid(row=1,column=3)
startstop.grid(row=0,column=5)
root.mainloop()
In addition, I tried to run these two programs from a different starting menu that used the console, which worked.
The console program is:
import timer_prog
timer_prog.timer()
raw_input('next')
import stopwatch
stopwatch.f()
Attached are some screenshots of what the stopwatch program should look like vs what it does look like when called from the starting program.
Note: I can tell the program is running from the starting page, as it prints the current time each second. Also, I attached some screenshots
Stopwatch Program Run Directly
Stopwatch Program Run From The Start Page

Tkinter program should use only one Tk() - to create main window - and one mainloop() - to control all windows and widgets. If you use two Tk() and two mainloop() then it has problem - for example get()/set() may not work.
Subwindows should use Toplevel() instead of Tk().
Function which starts program (ie. run()) could run with parameter window (def run(window)) and then you can execute it as standalone program with
root = Tk()
run(root)
root.mainloop()
or after importing
run(Toplevel())
(without maniloop())
You can use if __name__ == "__main__" to recognize if program starts as standalone.
Example
main.py
from Tkinter import *
class StartPage:
def __init__(self, master):
self.master = master
master.title("Timer Suite: Brian Ton")
Button(master, text="Timer", command=self.run_timer).pack()
Button(master, text="Stopwatch", command=self.run_stopwatch).pack()
def run_stopwatch(self):
import stopwatch
window = Toplevel()
stopwatch.run(window)
def run_timer(self):
import timer_prog
window = Toplevel()
timer_prog.timer(window)
self.master.after_cancel(timer_prog)
def main():
root = Tk()
StartPage(root)
root.mainloop()
main()
stopwatch.py
from Tkinter import *
import datetime
def pre_start():
start_button.config(state='disabled')
stop_button.config(state='normal')
reset_button.config(state='disabled')
start()
def start():
global current_time
# stop_button['state'] can be 'normal' or 'active' so better use ` != 'disabled'`
if reset_button['state'] == 'disabled' and stop_button['state'] != 'disabled':
current_time += 1
time_var.set(str(datetime.timedelta(seconds=current_time)))
print(time_var.get())
master.after(1000, start)
def stop():
start_button.config(state='disabled')
stop_button.config(state='disabled')
reset_button.config(state='normal')
def reset():
global current_time
start_button.config(state='normal')
stop_button.config(state='disabled')
reset_button.config(state='disabled')
current_time = 0
time_var.set(str(datetime.timedelta(seconds=0)))
def run(window):
global master
global current_time, time_var
global start_button, stop_button, reset_button
master = window
current_time = 0
time_var = StringVar()
time_var.set(str(datetime.timedelta(seconds=0)))
time_label = Label(window, textvariable=time_var)
time_label.grid(row=1, column=2)
start_button = Button(master, text='Start', command=pre_start, state='normal')
stop_button = Button(master, text='Stop', command=stop, state='disabled')
reset_button = Button(master, text='Reset', command=reset, state='disabled')
start_button.grid(row=2, column=1)
stop_button.grid(row=2, column=2)
reset_button.grid(row=2, column=3)
if __name__ == '__main__':
# it runs only in standalone program
root = Tk()
run(root)
root.mainloop()

How to add timer with start/stop GUI in python

I've been googeling all day, tried loads of different ways, but I can't get this code to work. I want a simple timer that run a function when you press "Start", and stops when you press "Stop".
Example:
When you press start, the function will print every second "Hello World", until you press stop.
My code with some comments so you can understand faster:
import sys
from Tkinter import *
from threading import Timer
# a boolean for telling the timer to stop
stop_timer = False
mgui = Tk()
def work(var):
# stop_timers sets to True or False with Start/Stop
stop_timer = var
# work_done will evaluate if timer should start or be canceled
def work_done(var2):
stop_timer = var2
# if stop was pressed t.start() will be ignored
if stop_timer == False:
t.start()
# if stop was pressed timer will stop
if stop_timer == True:
print "Stopped!"
t.cancel()
t = Timer(1, work, [False])
print "Something"
work_done(var)
mgui.geometry('450x450')
mgui.title('Test')
cmd1 = lambda: work(False)
btn = Button(mgui, text="Start", command =cmd1).place(x=50, y=50)
cmd2 = lambda: work(True)
btn2 = Button(mgui, text="Stop", command =cmd2).place(x=100, y=50)
mgui.mainloop()
As you can tell, I'm new to this shizzle!
Thanks, mates!

This is a generic timer, you can also implement one in tkinter using after:
import time
import Tkinter as tk
import threading
class MyTimer(threading.Thread):
def __init__(self, t):
super(MyTimer,self).__init__()
self.txt = t
self.running = True
def run(self):
while self.running:
self.txt['text'] = time.time()
mgui = tk.Tk()
mgui.title('Test')
txt = tk.Label(mgui, text="time")
txt.grid(row=0,columnspan=2)
timer = None
def cmd1():
global timer
timer = MyTimer(txt)
timer.start()
def cmd2():
global timer
if timer:
timer.running = False
timer= None
btn = tk.Button(mgui, text="Start", command =cmd1)
btn.grid(row=1,column=1)
btn2 = tk.Button(mgui, text="Stop", command =cmd2)
btn2.grid(row=1,column=2)
mgui.mainloop()

By editing some in xndrme's post, I finally got it to work. Thank you!
I'll post the code here for possible future googlers.
import sys
from Tkinter import *
from threading import Timer
mgui = Tk()
def cmd2():
global t
if t:
t.cancel()
def looper():
global t
t = Timer(1, looper)
t.start()
print "Hello World!"
mgui.geometry('450x450')
mgui.title('Test')
btn = Button(mgui, text="Start", command =looper).place(x=50, y=50)
btn2 = Button(mgui, text="Stop", command =cmd2).place(x=100, y=50)
mgui.mainloop()

How to update the window during a callback?

When a Tkinter button is clicked and the command is run, the GUI seems frozen until the command returns.
Example, the counter wont update until after 2 seconds:
import tkinter as tk
import time
class Window():
def __init__(self):
self.clicks = 0
self.root = tk.Tk()
self.button_text = tk.StringVar(value="Click " + str(self.clicks))
self.button = tk.Button(self.root, textvariable=self.button_text,
command=self.click)
self.button.pack()
def click(self):
self.clicks += 1
self.button_text.set("Click " + str(self.clicks))
time.sleep(2)
if __name__ == '__main__':
Window().root.mainloop()
Is there any way to allow the window to be updated during a callback?

You can call the button's update_idletasks method:
def click(self):
self.clicks += 1
self.button_text.set("Click " + str(self.clicks))
##################################
self.button.update_idletasks()
##################################
time.sleep(2)
Adding that line to click will cause the button's text to update immediately.

The sleep is blocking the gui's event loop