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Problem This is in response to Manar's post titled "How to disconnect an event?"
He has set up a button-press-event, and he would like to switch the signal handler processing the button-press-event depending on some conditions.
In Part 1 we used the methods connect() and disconnect().
In this Part 2, we'll use the methods block() and unblock() as shown below:
Solution
- If you need to 'connect', 'disconnect' and 'reconnect' a signal repeatedly such as the case shown in this example, you might want to consider using GObject::block() and GObject::unblock($signal_handler_id) (instead of connect/disconnect) to switch the signal handlers.
- The effect of the above sample code is exactly the same as that of the previous example using connect/disconnect.
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$window = new GtkWindow();
$window->set_size_request(400, 175);
$window->connect_simple('destroy', array('Gtk','main_quit'));
$window->add($vbox = new GtkVBox());
// display title
$title = new GtkLabel("Switching signal handlers on the fly\n".
"Part 2 - using block / unblock");
$title->modify_font(new PangoFontDescription("Times New Roman Italic 10"));
$title->modify_fg(Gtk::STATE_NORMAL, GdkColor::parse("#0000ff"));
$title->set_size_request(-1, 40);
$vbox->pack_start($title, 0);
$vbox->pack_start(new GtkLabel(), 0);
$label = new GtkLabel('Click on the blue sqaure once. '.
'It will change to green.');
$vbox->pack_start($label, 0);
setup_colorbox('#0000ff', 'blue', $vbox); // note 1
$window->show_all();
Gtk::main();
function setup_colorbox($color, $label, $vbox) {
$hbox = new GtkHBox();
$hbox->set_size_request(30, 30);
$eventbox = new GtkEventBox();
$eventbox->add($hbox);
$eventbox->modify_bg(Gtk::STATE_NORMAL, GdkColor::parse($color));
global $signal_id1, $signal_id2;
$signal_id1 = $eventbox->connect('button-press-event',
'on_button_press1'); // note 2
$signal_id2 = $eventbox->connect('button-press-event',
'on_button_press2'); // note 2
$eventbox->block($signal_id2); // note 3
$hbox = new GtkHBox();
$vbox->pack_start($hbox, 0);
$hbox->pack_start(new GtkLabel());
$hbox->pack_start($eventbox, 0);
$hbox->pack_start(new GtkLabel());
}
function on_button_press1($eventbox, $event) {
if ($event->type!=Gdk::BUTTON_PRESS) return false;
echo "on_button_press1!\n";
$eventbox->modify_bg(Gtk::STATE_NORMAL,
GdkColor::parse('#00ff00'));
global $signal_id1, $signal_id2;
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- Note that this is only 70% of the sample code. You have to be a registered member to see the entire sample code. Please login or register.
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- Have some doubt about the registration? Please read this forum article.
Explanation We make use of the code from How to switch signal handlers on the fly - Part 1 - using connect disconnect?
What's new here:
- Set up the blue color box.
- Set up the
button-press-event signal. Note that here we register two callback functions on the same button. Don't forget to take note of the signal handler id's.
- Block the second callback function so that only the first one is active.
- Block the first callback function and unblock the second callback function.
- Block the second callback function and unblock the first callback function.
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