Saturday, June 22, 2013

Calling a function periodically in Tkinter (Polling)

Use the

after
method. From a discussion here.

import Tkinter as tki, time

class App(object):

  def __init__(self):
    self.root = tki.Tk()
    self.win = tki.Text(self.root, undo=True, width=20, height=5)
    self.win.pack(side='top', expand=True, fill='both')
    self.poll()

  def poll(self):
    print time.strftime('%H:%M:%S')
    self.win.insert(tki.END, time.strftime('%H:%M:%S') + '\n')
    self.root.after(1000, self.poll)

app = App()
app.root.mainloop() 

From a further discussion here, use the after_cancel method to cancel the polling. after returns a job id that you need for the cancellation

import Tkinter as tki, time

class App(object):

  def __init__(self):
    self.root = tki.Tk()
    self.win = tki.Text(self.root, undo=True, width=10, height=1)
    self.win.pack(side='left')
    self.cancel = tki.Button(self.root,text='Stop',command=self.stop)
    self.cancel.pack(side='left')
    self._poll_job_id = self.poll()

  def poll(self):
    print time.strftime('%H:%M:%S')
    self.win.delete(1.0,tki.END)
    self.win.insert(tki.END, time.strftime('%H:%M:%S') + '\n')
    self._poll_job_id = self.root.after(1000, self.poll)

  def stop(self):
    self.root.after_cancel(self._poll_job_id)
    self.cancel.configure(text='Go',command=self.go)

  def go(self):
    self.cancel.configure(text='Stop',command=self.stop)
    self._poll_job_id = self.poll()

app = App()
app.root.mainloop() 

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