Python GTK Print preview

test.py

#!/usr/bin/python3
import gi
gi.require_version('Gtk', '3.0')
gi.require_version('Poppler', '0.18')
from gi.repository import GObject, Gtk, Poppler


class MyApp():

    def __init__(self):

        settings = Gtk.Settings.get_default()
        Gtk.Settings.get_default().set_property("gtk-print-preview-command", "xreader-previewer --unlink-tempfile --print-settings %s %f")

        self.window = Gtk.Window()
        button = Gtk.Button()
        button.set_label("Click me")

        self.window.add(button)
        self.window.show_all()

        self.window.connect("destroy", Gtk.main_quit)
        button.connect("clicked", self.on_button_clicked)

        self.operation = Gtk.PrintOperation()

        self.operation.connect('begin-print', self.begin_print, None)
        self.operation.connect('draw-page', self.draw_page, None)
        # self.operation.connect('preview', self.preview, None)

        self.doc = Poppler.Document.new_from_file("file:///home/clem/AttestationScolaire.pdf")

    def begin_print(self, operation, print_ctx, print_data):
        operation.set_n_pages(self.doc.get_n_pages())

    def draw_page(self, operation, print_ctx, page_num, print_data):
        cr = print_ctx.get_cairo_context()
        page = self.doc.get_page(page_num)
        page.render(cr)

    def preview(self, operation, preview, print_ctx, parent, print_data):
        print("PREVIEW")
        return True


    def on_button_clicked(self, button):
        result = self.operation.run(Gtk.PrintOperationAction.PRINT_DIALOG, self.window)


app = MyApp()
Gtk.main()