Best Practice for Progress Bar in Python PyGTK

Question

I would like to receive feedback on the opinions of other experts on how to implement the progress bar in Python PyGTK.

The work that the progress bar was supposed to display was very computationally significant. Therefore, I wanted the work to be performed in a separate process (thereby giving the operating system the ability to run it on a different kernel). I wanted to be able to get started, and then continue to use the GUI for other tasks, waiting for the results.

I saw how many people asked this question indirectly, but I did not see specific expert advice. I hope that by asking this question we will see a joint examination of the community.

Answer 1

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Python, . , .

import gobject
import pygtk
pygtk.require('2.0')
import gtk
import multiprocessing
import threading
import time

gtk.gdk.threads_init()

class Listener(gobject.GObject):
    __gsignals__ = {
        'updated' : (gobject.SIGNAL_RUN_LAST,
                     gobject.TYPE_NONE,
                     (gobject.TYPE_FLOAT, gobject.TYPE_STRING)),
        'finished': (gobject.SIGNAL_RUN_LAST,
                     gobject.TYPE_NONE,
                     ())
    }

    def __init__(self, queue):
        gobject.GObject.__init__(self)
        self.queue = queue

    def go(self):
        print "Listener has started"
        while True:
            # Listen for results on the queue and process them accordingly                            
            data = self.queue.get()
            # Check if finished                                                                       
            if data[1]=="finished":
                print "Listener is finishing."
            self.emit("finished")
            return
            else:
                self.emit('updated', data[0], data[1])

gobject.type_register(Listener)

class Worker():
    def __init__(self, queue):
        self.queue = queue

    def go(self):
        print "The worker has started doing some work (counting from 0 to 9)"
        for i in range(10):
        proportion = (float(i+1))/10
        self.queue.put((proportion, "working..."))
            time.sleep(0.5)
        self.queue.put((1.0, "finished"))
        print "The worker has finished."


class Interface:
    def __init__(self):
        self.process = None
        self.progress = gtk.ProgressBar()
        button = gtk.Button("Go!")
        button.connect("clicked", self.go)
        vbox = gtk.VBox(spacing=5)
        vbox.pack_start(self.progress)
        vbox.pack_start(button)
        vbox.show_all()
        self.frame = vbox

    def main(self):
        window = gtk.Window(gtk.WINDOW_TOPLEVEL)
        window.set_border_width(10)
        window.add(self.frame)
        window.show()
        window.connect("destroy", self.destroy)

        gtk.main()

    def destroy(self, widget, data=None):
        gtk.main_quit()


    def callbackDisplay(self, obj, fraction, text, data=None):
        self.progress.set_fraction(fraction)
        self.progress.set_text(text)

    def callbackFinished(self, obj, data=None):
        if self.process==None:
            raise RuntimeError("No worker process started")
        print "all done; joining worker process"
        self.process.join()
        self.process = None

        self.progress.set_fraction(1.0)
        self.progress.set_text("done")

   def go(self, widget, data=None):
        if self.process!=None:
            return

        print "Creating shared Queue"
        queue = multiprocessing.Queue()

        print "Creating Worker"
        worker = Worker(queue)

        print "Creating Listener"
        listener = Listener(queue)
        listener.connect("updated",self.callbackDisplay)
        listener.connect("finished",self.callbackFinished)

        print "Starting Worker"
        self.process = multiprocessing.Process(target=worker.go, args=())
        self.process.start()

        print "Starting Listener"
        thread = threading.Thread(target=listener.go, args=())
        thread.start()

if __name__ == '__main__':
    gui = Interface()
    gui.main()

, , :

• GObject Python
• , gtk.gdk.threads_init