#!/usr/bin/perl -w
use strict;
use Gtk2 -init;
my $image = Gtk2::Image->new_from_file ($ARGV[0]);
my $window = Gtk2::Window->new;
my $eventbox = Gtk2::EventBox->new;

$eventbox->signal_connect_after (realize => sub {
    my ($widget) = @_;
    warn "realize\n";
    $widget->{drag_gc} = Gtk2::Gdk::GC->new ($widget->window);
    $widget->{drag_gc}->set_function ('xor');
    $widget->{drag_gc}->set_foreground ($widget->style->white);
});

$eventbox->signal_connect_after (unrealize => sub {
    my ($widget) = @_;
    delete $widget->{drag_gc};
});

sub min { $_[0] < $_[1] ? $_[0] : $_[1] }

sub draw_rubber_band_box {
    my ($widget) = @_;
    my $x = min ($widget->{draginfo}{x1}, $widget->{draginfo}{x2});
    my $y = min ($widget->{draginfo}{y1}, $widget->{draginfo}{y2});
    my $w = abs ($widget->{draginfo}{x2} - $widget->{draginfo}{x1});
    my $h = abs ($widget->{draginfo}{y2} - $widget->{draginfo}{y1});
    $widget->window->draw_rectangle
		($widget->{drag_gc}, 1, $x, $y, $w, $h);
}

$eventbox->signal_connect (button_press_event => sub {
    my ($widget, $event) = @_;

    if ($event->button == 1) {
        $widget->{draginfo} = {
            x1 => $event->x,
            y1 => $event->y,
            x2 => $event->x,
            y2 => $event->y,
        };
        # Draw...
        draw_rubber_band_box ($widget);
    }

    return 0;
});

$eventbox->signal_connect (motion_notify_event => sub {
    my ($widget, $event) = @_;

    if ($widget->{draginfo}) {
        # Erase...
        draw_rubber_band_box ($widget);

        $widget->{draginfo}{x2} = $event->x;
        $widget->{draginfo}{y2} = $event->y;

        # Draw new...
        draw_rubber_band_box ($widget);
    }

    return 0;
});

$eventbox->signal_connect (button_release_event => sub {
    my ($widget, $event) = @_;

    if ($widget->{draginfo}) {
        # Erase...
        draw_rubber_band_box ($widget);
    }

    # Step out of rubber-band mode.
    delete $widget->{draginfo};

    return 0;
});

$eventbox->add ($image);
$window->add ($eventbox);
$window->show_all ();
$window->signal_connect (destroy => sub { Gtk2->main_quit () });
Gtk2->main ();