There are several things wrong with your code. First of all you shouldn't use time.sleep()
in a Tkinter program because it interferes with the mainloop()
. Instead one typically uses the universal widget method .after()
to schedule a function to run after a specified delay.
Secondly you're not using global variables correctly. When you assign a value to a named variable in a function, it will create a local variable unless that name has been previous declared global
. So for instance, your stop()
function is creating a local variable named running
and setting its value to 0, not changing the value of the global variable with the same name.
The previous rule doesn't apply to just referencing (reading) the current value of a variable. That is why it was OK to not have declared Freq
and Dur
globals in start()
.
Another problem is with the sec % 1 == 0
in your start()
function. Any value % 1
is 0
. To check odd/evenness use sec % 2
.
Here's a working version which has also been reformatted to follow PEP 8 - Style Guide for Python Code more closely.
try:
import tkinter as tk
except ModuleNotFoundError:
import Tkinter as tk # Python 2.
import time
import winsound
FREQ = 2500
DUR = 150
after_id = None
secs = 0
def beeper():
global after_id
global secs
secs += 1
if secs % 2 == 0: # Every other second.
winsound.Beep(FREQ, DUR)
after_id = top.after(1000, beeper) # Check again in 1 second.
def start():
global secs
secs = 0
beeper() # Start repeated checking.
def stop():
global after_id
if after_id:
top.after_cancel(after_id)
after_id = None
if __name__ == '__main__':
top = tk.Tk()
top.title('MapAwareness')
top.geometry('200x100')
startButton = tk.Button(top, height=2, width=20, text="Start", command=start)
stopButton = tk.Button(top, height=2, width=20, text="Stop", command=stop)
startButton.pack()
stopButton.pack()
top.mainloop()
Update
Since this answer has become fairly popular, I'd like touch on another slightly more advanced topic — namely how making the code more object-oriented would simplify things by eliminating the need almost all of the global variables.
try:
import tkinter as tk
except ModuleNotFoundError:
import Tkinter as tk # Python 2.
import time
import winsound
FREQ = 2500
DUR = 150
class Application(tk.Frame, object):
def __init__(self, master=None):
super(Application, self).__init__(master) # Call baseclass constructor.
self.after_id = None
self.secs = 0
# Create widgets,
startButton = tk.Button(top, height=2, width=20, text="Start", command=self.start)
stopButton = tk.Button(top, height=2, width=20, text="Stop", command=self.stop)
startButton.pack()
stopButton.pack()
def beeper(self):
self.secs += 1
if self.secs % 2 == 0: # Every other second.
winsound.Beep(FREQ, DUR)
self.after_id = top.after(1000, self.beeper) # Check again in 1 second.
def start(self):
self.secs = 0
self.beeper() # Start repeated checking.
def stop(self):
if self.after_id:
top.after_cancel(self.after_id)
self.after_id = None
if __name__ == '__main__':
top = tk.Tk()
app = Application()
app.master.title('MapAwareness')
app.master.geometry('200x100')
app.mainloop()