[Tkinter-discuss] non-GUI event detection in Tkinter mainloop()

[O'Gorman, Lawrence (Larry)]

Thanks very much to all those who responded to me and thanks to my good
buddy and Python wiz, Kirke. I've included my code below, which
periodically checks if a file is changed, and if so, it changes the
image displayed in a window. The trick (as suggested) was to use "after"
to get the event to repeatedly call itself. In the code below this is
showStatus.after() at the end of the checkFileMod() function.

--

import Tkinter

import os

 

root = Tkinter.Tk()

 

# initialize parameters

checkFile = "C:/BTL/Code/GC/IPSi/test3.txt"  # check if this file
changed

img1=Tkinter.PhotoImage(file='./img1.gif')  # display image 1

img2=Tkinter.PhotoImage(file='./img2.gif')  # display image 2

interval = 3000                              # time [msec] between
checking

 

# label widget shows status of image being displayed

showStatus = Tkinter.Label()

showStatus.pack()

 

# canvas widget displays image that changes when file changes

canvas=Tkinter.Canvas(root, width=400, height=400)

canvas.create_image(145,280, image=img1)

canvas.bind("<Button-1>", quitThis)   # bind left mouse button to quit
app

canvas.pack()

 

# function quits application

def quitThis(event):

    canvas.destroy()

    root.destroy()

    root.quit()

 

# function changes canvas if file is modified

def checkFileMod():

    global imgNum

    global fileStatus, fileStatusB4

    fileStatus = os.stat(checkFile)

    print "file status: ", fileStatus.st_mtime

    if fileStatus != fileStatusB4:

        print "CHANGED"

        if imgNum == 1:

            showStatus.config(text="img2")

            imgNum = 2

            canvas.create_image(145,280, image=img2)

            canvas.pack()

        else:

            showStatus.config(text="img1")

            imgNum = 1

            canvas.create_image(145,280, image=img1)

            canvas.pack()

    fileStatusB4 = fileStatus

    showStatus.after(interval, checkFileMod)

 

# run with initial values before loop

imgNum = 1

showStatus.config(text="img1")

fileStatusB4 = os.stat(checkFile)            # file status before

 

#loop

checkFileMod()

showStatus.mainloop()

 

 

 

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