Tkinter : how to make an action before closing the window ?

[Borenis]

Hi,

I'm trying to make a small application that uses parralel port for remote control of an audio amplifier (on/off).

I use a Tkinter object to set/reset one of the line of the parallel port.

My problem is to find a way to reset the line when windows closes (when I switch of the computer), to avoid damaging my loudspeakers.

Is there an event that I could use ? Like the event of a mouse clic on the "X" on top of the window (=alt+F4)

I'm a beginner (2 days), i find it difficult to find the informations I need (but Python is incredibly powerfull !)

Thanks for your help !

[dwblas]

You would use a normal function that contains the code to shut down the amp and then quits.

import Tkinter
import BusyBar


class Application:
    def __init__(self, root):
        self.root = root
        self.root.title('BusyBar Demo')
        fr = Tkinter.Frame(self.root, width=300, height=100).pack()

        bb = BusyBar.BusyBar(fr, width=200)
        bb.place(x=40, y=20)
        bb.on()

        exit_button= Tkinter.Button(fr, text='EXIT',
                   command=self.switch_off, bg='red', fg='white' )
        exit_button.pack(fill=Tkinter.X, expand=1)

    def switch_off(self):
        print "switching off the amp now"
        self.root.quit()

if __name__ == '__main__':
    root = Tkinter.Tk()
    Application(root)
    root.mainloop()

[Borenis]

Thanks for answering so quickly !

I have 2 problems with your answer :

- I can't find BusyBar (i'm using Python 2.7)... Where can I download it?

- the aim of my program is to protect the amp against mistakes, like exiting the os (windows xp), forgetting to switch them off. So, I don't think you're solution would match with my need. But, I cannot test it (because of BusyBar)

And... Perhaps I'haven't understood your solution ?

Thanks a lot for your help

Is there anything to do with signal ?

My program :

# -*- coding: cp1252 -*-

import parallel
from Tkinter import *

def setvalue():
    p.setData(1)
    
def resetvalue():
    p.setData(0)

def fin():
    fen1.destroy()

p=parallel.Parallel()

fen1= Tk()
tex1 = Label(fen1, text='Commande du port parallèle', fg='red')
tex1.pack()
bou1 = Button(fen1, text='set', command = setvalue)
bou1.pack()
bou2 = Button(fen1, text='reset', command = resetvalue)
bou2.pack()
bou3 = Button(fen1, text='Quitter', command = fin)
bou3.pack()

fen1.mainloop()

[dwblas]

Use fin() to execute what ever code you want to shut down the amp. The code should be executed before the destroy() statement though as that shuts down the GUI.

[Borenis]

Hi,

I've had a little success, using the os signals, with this :
_______________ _______________ _________

from Tkinter import *
import parallel

root = Tk()

def Intercepte():
    print "Interception de la fermeture de la fenetre"
    resetvalue()
    root.destroy()

p=parallel.Parallel()
    
def setvalue():
    p.setData(1)
    
def resetvalue():
    p.setData(0)

root.protocol("WM_DELETE_WINDOW", Intercepte)
root.title("Commande du port parallele")


tex1 = Label(root, text='Commande du port parallele', fg='red')
tex1.pack()
bou1 = Button(root, text='set', command = setvalue)
bou1.pack()
bou2 = Button(root, text='reset', command = resetvalue)
bou2.pack()

root.mainloop()

_______________ _______________ _____

When I close the window, the parallel port is resetted, great !
But it doesn't work when Windows (XP) closes... :-(

I've tried WM_KILL, but it doesn't work.

You've sent me a sample code, I'd like to see what it does, but I've been unable to find BusyBar. Where can I download it ?

Thanks a lot,

Sylvain

[dwblas]

Start here for busybar.