Periodically call a function in pygtk's main loop

Question

What’s the pygtk equivalent for after method in tkinter?

I want to periodically call a function in the main loop.

What is the better way to achieve it?

Asked By: houqp

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Source

Answer 1

Use gobject.timeout_add:

import gobject
gobject.timeout_add(milliseconds, callback)

For example here is a progress bar that uses timeout_add to update the progress (HScale) value:

import gobject
import gtk

class Bar(object):
    def __init__(self,widget):
        self.val=0
        self.scale = gtk.HScale()
        self.scale.set_range(0, 100)
        self.scale.set_update_policy(gtk.UPDATE_CONTINUOUS)
        self.scale.set_value(self.val)
        widget.add(self.scale)
        gobject.timeout_add(100, self.timeout)
    def timeout(self):
        self.val +=1
        self.scale.set_value(self.val)
        return True

if __name__=='__main__':
    win = gtk.Window()
    win.set_default_size(300,50)
    win.connect("destroy", gtk.main_quit)
    bar=Bar(win)
    win.show_all()
    gtk.main()

Answered By: unutbu

Answer 2

If you’re using the new Python GObject Introspection API, you should use GLib.timeout_add().

Note that the documentation seems to be incorrect. It is actually:

timeout_add(interval, function, *user_data, **kwargs)

Here’s an example. Note that run is a callable object, but it could be any ordinary function or method.

from gi.repository import GLib

class Runner:
    def __init__(self, num_times):
        self.num_times = num_times
        self.count = 0

    def __call__(self, *args):
        self.count += 1
        print("Periodic timer [{}]: args={}".format(self.count, args))

        return self.count < self.num_times

run = Runner(5)

interval_ms = 1000
GLib.timeout_add(interval_ms, run, 'foo', 123)

loop = GLib.MainLoop()
loop.run()

Output:

$ python3 glib_timeout.py 
Periodic timer [1]: args=('foo', 123)
Periodic timer [2]: args=('foo', 123)
Periodic timer [3]: args=('foo', 123)
Periodic timer [4]: args=('foo', 123)
Periodic timer [5]: args=('foo', 123)
<messages stop but main loop keeps running>

Answered By: Jonathon Reinhart

Answer 3

or the simplest test code
// base on Jonathon Reinhart’s answer

from gi.repository import GLib

i = 0
def test1(*args):
    global i
    i+=1
    print('test1:', i, args)
    if i<3:
        return True # keep running
    else:
        return False # end timer

# call test1 every 1000ms, until it return False
GLib.timeout_add(1000, test1, 'foo', 123)

loop = GLib.MainLoop() # just for test without UI
loop.run()

outputs:

$ python3 ../test_gtk_timeout.py
test1: 1 ('foo', 123)
test1: 2 ('foo', 123)
test1: 3 ('foo', 123)

Answered By: yurenchen

Periodically call a function in pygtk's main loop

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