Using Gtk.spinner with a long time function

Question

I am trying to get working a gtk.spinner using Pygobject in python. The main thing is that I use this element to show the user that a long time action is in progress. The problem is that the spinner stops when doing the function.

the code is here:

.....
def create_image(self,spinner):
    ....
    spinner.start()
    # Heavy function
    spinner.stop()
.....

And this doesn't works. I would accept some help, thanks!

Answer 1

Your heavy function needs to occasionally let the GUI process accumulated events. For example, you can occasionally run:

while gtk.events_pending():
    gtk.main_iteration()

Another option is for the heavy function to run in a separate thread, leaving the main thread to process the events and spin the spinner. In that case, you will need to redesign your create_image function to be asynchronous. For example:

def create_image(self, spinner, finishcb):
    spinner.start()

    def thread_run():
        # call heavy here
        heavy_ret = heavy()
        gobject.idle_add(cleanup, heavy_ret)

    def cleanup(heavy_ret):
        spinner.stop()
        t.join()
        finishcb(heavy_ret)

    # start "heavy" in a separate thread and immediately
    # return to mainloop
    t = threading.Thread(thread_run)
    t.start()

Now, instead of calling create_image, you need to pass it a callback that will be called when the image is ready. I.e., instead of:

image = self.create_image(spinner)

you write:

self.create_image(spinner, self.store_created_image)