python - Run an infinite loop in the backgroung in Tkinter

Question

I would like the code to run in the background and to update my GUI periodically. How can I accomplish this?

For example, suppose I want to execute something like this in the background of the GUI code you can see below:

x = 0

while True:
   print(x)
   x = x + 1
   time.sleep(1)

This is the GUI code:

class GUIFramework(Frame):

    def __init__(self,master=None):
        Frame.__init__(self,master)
        self.master.title("Volume Monitor")
        self.grid(padx=10, pady=10,sticky=N+S+E+W)
        self.CreateWidgets()

    def CreateWidgets(self):
        textOne = Entry(self, width=2)
        textOne.grid(row=1, column=0)

        listbox = Listbox(self,relief=SUNKEN)
        listbox.grid(row=5,rowspan=2,column=0,columnspan=4,sticky=N+W+S+E,pady=5)
        listbox.insert(END,"This is an alert message.")

if __name__ == "__main__":
    guiFrame = GUIFramework()
    guiFrame.mainloop()

Answer 1

It is a little unclear what your code at the top is supposed to do, however, if you just want to call a function every second (or every the amount of seconds you want), you can use the after method.

So, if you just want to do something with textOne, you'd probably do something like:

...
textOne = Entry(self, width=2)
textOne.x = 0

def increment_textOne():
    textOne.x += 1

    # register "increment_textOne" to be called every 1 sec
    self.after(1000, increment_textOne) 

You could make this function a method of your class (in this case I called it callback), and your code would look like this:

class Foo(Frame):

    def __init__(self, master=None):
        Frame.__init__(self, master)
        self.x = 0
        self.id = self.after(1000, self.callback)

    def callback(self):
        self.x += 1
        print(self.x)
        #You can cancel the call by doing "self.after_cancel(self.id)"
        self.id = self.after(1000, self.callback)  

gui = Foo()
gui.mainloop()