from gi.repository import GLib

from gi.repository import Gtk

import sys

class MyWindow(Gtk.ApplicationWindow):

    # a window

    def __init__(self, app):

        Gtk.Window.__init__(self, title="ProgressBar Example", application=app)

        self.set_default_size(220, 20)

        # a progressbar

        self.progress_bar = Gtk.ProgressBar()

        # add the progressbar to the window

        self.add(self.progress_bar)

        # the method self.pulse is called each 100 milliseconds

        # and self.source_id is set to be the ID of the event source

        # (i.e. the bar changes position every 100 milliseconds)

        self.source_id = GLib.timeout_add(100, self.pulse)

    # event handler

    # any signal from the keyboard controls if the progressbar stops/starts

    def do_key_press_event(self, event):

        # if the progressbar has been stopped (therefore source_id == 0 - see

        # "else" below), turn it back on

        if (self.source_id == 0):

            self.source_id = GLib.timeout_add(100, self.pulse)

        # if the bar is moving, remove the source with the ID of source_id

        # from the main context (stop the bar) and set the source_id to 0

        else:

            GLib.source_remove(self.source_id)

            self.source_id = 0

        # stop the signal emission

        return True

    # source function

    # the progressbar is in "activity mode" when this method is called

    def pulse(self):

        self.progress_bar.pulse()

        # call the function again

        return True

class MyApplication(Gtk.Application):

    def __init__(self):

        Gtk.Application.__init__(self)

    def do_activate(self):

        win = MyWindow(self)

        win.show_all()

    def do_startup(self):

        Gtk.Application.do_startup(self)

app = MyApplication()

exit_status = app.run(sys.argv)

sys.exit(exit_status)