Update Gtk.Label dynamicall when time changes - gtk

Question

I'm using this code to write the current time as a Gtk.Label in an app.
public bool update_time () {
var now = new GLib.DateTime.now_local ();
var settings = new GLib.Settings ("org.gnome.desktop.interface");
var time_format = Granite.DateTime.get_default_time_format (settings.get_enum ("clock-format") == 1, false);
time1_label = new Gtk.Label (now.format (time_format)) {
halign = Gtk.Align.CENTER,
valign = Gtk.Align.CENTER,
margin_top = 5
};
time1_label.get_style_context ().add_class (Granite.STYLE_CLASS_H3_LABEL);
time1_label.tooltip_text = time_format;
time1_label.xalign = 0;
return true;
}
The time shows correctly, but I want the label to update to the latest time when it changes. How can I do that?
Maybe use Timeout in some way, but I can't figure out how.

Answer 1

You'll have to create a Timeout, and in its callback change the text of time1_label. (Use Gdk.threads_add_timeout() to add the timeout callback in case any dependencies might be using deprecated GTK locking mechanisms.)

Answer 2

You can use the Timeout as in this example:
public class RefreshLabel : Gtk.Application {
private uint[] timeout_id;
private Gtk.Label label;
public RefreshLabel () {
Object (
application_id: "refreh.my.label",
flags: ApplicationFlags.FLAGS_NONE
);
}
protected override void activate () {
Gtk.ApplicationWindow window = new Gtk.ApplicationWindow (this);
window.set_default_size (100, 50);
window.window_position = Gtk.WindowPosition.CENTER;
window.set_border_width(10);
// create the timeout with your callback that update the label every 1 second
timeout_id += Timeout.add_seconds_full (GLib.Priority.DEFAULT, 1, update_time);
label = new Gtk.Label ("");
var now = new GLib.DateTime.now_local ();
label.set_markup ("<big>" + now.format ("%x %X") + "</big>");
Gtk.Box vbox = new Gtk.Box (Gtk.Orientation.VERTICAL, 0);
vbox.pack_start (label, false, false, 0);
window.add (vbox);
window.show_all ();
}
protected override void shutdown () {
// On close all instance of the timeout must be closed
foreach (var id in timeout_id)
GLib.Source.remove (id);
base.shutdown ();
}
public bool update_time () {
var now = new GLib.DateTime.now_local ();
label.set_markup ("<big>" + now.format ("%x %X") + "</big>");
return true;
}
public static int main (string[] args) {
RefreshLabel app = new RefreshLabel ();
return app.run (args);
}
}