Delaying a function

Syntax#

widget.after(delay_ms, callback, *args)

Parameters#

Parameter	Description
delay_ms	Time (milliseconds) which is delayed the call to the function `callback`
callback	Function that is called after the given `delay_ms`. If this parameter is not given, `.after` acts similar to `time.sleep` (in milliseconds)
## Remarks#
Syntax assumes a `widget` accepted by the method `.after` has been previously created (i.e `widget=tk.Label(parent)`)
## .after()
`.after(delay, callback=None)` is a method defined for all tkinter widgets. This method simply calls the function `callback` after the given `delay` in ms. If no function is given, it acts similar to `time.sleep` (but in milliseconds instead of seconds)

Here is an example of how to create a simple timer using after:

# import tkinter
try:
    import tkinter as tk
except ImportError:
    import Tkinter as tk

class Timer:
    def __init__(self, parent):
        # variable storing time
        self.seconds = 0
        # label displaying time
        self.label = tk.Label(parent, text="0 s", font="Arial 30", width=10)
        self.label.pack()
        # start the timer
        self.label.after(1000, self.refresh_label)

    def refresh_label(self):
        """ refresh the content of the label every second """
        # increment the time
        self.seconds += 1
        # display the new time
        self.label.configure(text="%i s" % self.seconds)
        # request tkinter to call self.refresh after 1s (the delay is given in ms)
        self.label.after(1000, self.refresh_label)

if __name__ == "__main__":
    root = tk.Tk()
    timer = Timer(root)
    root.mainloop()