Gtk3::Application example (WAS: Override of Gtk3::Application->new)

[Jeremy Volkening <jdv base2bio com>]

Hello Max,

The structure of a GtkApplication program is different than that of a "Gtk2
mainloop"-style application. You should't call Gtk3::init - that is handled
automatically. All of the program initialization is supposed to be done inside
of the 'startup' and 'activate' callbacks. Instead of calling Gtk3::main and
Gtk3::quit, you call the GApplication 'run' and 'quit' methods (therefore you
also need to import Glib::IO). This is the most useful site I've found:

https://wiki.gnome.org/HowDoI/GtkApplication

The problems you're encountering relate to the fact that the App hasn't been
intitialized yet. At the bottom is a working example.

Regards,
Jeremy


use strict;
use warnings;

use Gtk3;
use Glib::IO;
use Glib qw/TRUE FALSE/;

my $app = Gtk3::Application->new('app.test', 'flags-none');

$app->signal_connect('startup'  => \&_init     );
$app->signal_connect('activate' => \&_build_ui );
$app->signal_connect('shutdown' => \&_cleanup  );

$app->run(\ ARGV);

exit;

sub _init {

    my ($app) = @_;

    # Handle program initialization
    print "Hello world!\n";

}

sub _build_ui {

    my ($app) = @_;

    my $window = Gtk3::ApplicationWindow->new($app);
    $window->set_title ("Gtk3 Menu Example");
    $window->set_default_size (200, 200);
    $window->signal_connect( "delete_event" => sub {$app->quit()} );
    $window->show();

}

sub _cleanup {

    my ($app) = @_;

    # Handle cleanup
    print "Goodbye world!\n";
    
}