Python and GTK+3: widget for choosing a keyboard shortcut

Question

I'm looking for a way to add a shortcut chooser widget on a dialog with Python and GTK+3.

I tried to search through all available widgets and don't seem to find any out-of-the-box solution. What would be my best call in that respect? Should I use a GtkEntry and intercept a key press?

Even though it seems like a pretty common use case, I failed to find any working example of that.

Answer 1

I have implemented this myself using a separate dialog. There's a regular button displaying the current assignment, which, when clicked, opens a KeyboardShortcutDialog implemented as follows:

class KeyboardShortcutDialog(Gtk.Dialog):
    """Dialog that allows to grab a keyboard shortcut."""

    def __init__(self, parent):
        Gtk.Dialog.__init__(self, _("Keyboard shortcut"), parent, 0)
        self.shortcut = None
        self.set_border_width(32)

        # Add a label
        label = Gtk.Label(xalign=0.5, yalign=0.5)
        label.set_markup(
            _('Press the desired key combination, <b>Backspace</b> to remove any shortcut, or <b>Esc</b> to cancel.'))
        self.get_content_area().pack_start(label, True, True, 0)
        self.connect('key-press-event', self.on_key_press)
        self.show_all()

    def on_key_press(self, widget, event: Gdk.EventKey):
        """Signal handler: key pressed."""
        keyval = event.get_keyval()[1]
        name = Gdk.keyval_name(keyval)

        # For some reason event.is_modifier == 0 here, even for modifier keys, so we need to resort to checking by name
        if name not in [
                'Shift_L', 'Shift_R', 'Control_L', 'Control_R', 'Meta_L', 'Meta_R', 'Alt_L', 'Alt_R', 'Super_L',
                'Super_R', 'Hyper_L', 'Hyper_R']:
            logging.debug('Key pressed: state=%s, keyval=%d', event.state, keyval)
            self.shortcut = (
                keyval,
                event.state &
                (Gdk.ModifierType.META_MASK | Gdk.ModifierType.SUPER_MASK | Gdk.ModifierType.HYPER_MASK |
                 Gdk.ModifierType.SHIFT_MASK | Gdk.ModifierType.CONTROL_MASK | Gdk.ModifierType.MOD1_MASK))
            self.response(Gtk.ResponseType.ACCEPT)
        return True

    def run(self):
        """Show the dialog and block until it's closed.
        :return: tuple (keyval, state) of the key captured or None if the dialog has been closed."""
        super().run()
        return self.shortcut

The dialog's run() method returns a tuple specifying the pressed key combination.