#!/usr/bin/perl
use warnings;
use strict;
use Glib qw/TRUE FALSE/;
use Gtk2 -init;
use Image::ExifTool;
use Geo::Coordinates::UTM;

#geoTiff File (static)
my $filename = 'q3639_DRG24k-c.tif';

#geostats
my $ellipsoid = 23; #static WSG83
my $zone;
my @mtp;
my @ps;
my @cs;

#Create Window
my $window = new Gtk2::Window ( "toplevel" );
$window->signal_connect ("delete_event", sub { Gtk2->main_quit; });
$window->set_border_width (10);
$window->set_size_request(640,480);
$window->set_position('center');

#create Table
my $table = Gtk2::Table->new(1, 1, FALSE);

#Create Scrolled Window
my $scwin = Gtk2::ScrolledWindow->new();
$scwin->set_policy('always','always');

#Create Viewport
my $vp = Gtk2::Viewport->new (undef,undef);

#add GeoTiff
my $exifTool = new Image::ExifTool;
my $info = $exifTool->ImageInfo($filename);
foreach (sort keys %$info) {
    print "$_ => $$info{$_}\n";
    
    #Find the right keys(data)
    if ($_ eq "ModelTiePoint"){
        @mtp = split(/ /,$$info{$_});
    }
    if ($_ eq "PixelScale"){
        @ps = split(/ /,$$info{$_});
    }
    if ($_ eq "ProjectedCSType"){
        @cs = split(/ /,$$info{$_});
        $zone = $cs[3];
    }
}
    
my $pixbuf = Gtk2::Gdk::Pixbuf->new_from_file ($filename);
my $widget = Gtk2::Image->new_from_pixbuf ($pixbuf);

#Create Eventbox and Pack mouse signal
my $ebox = Gtk2::EventBox->new;
$ebox->set_events( 'button_press_mask' );
$ebox->signal_connect( button_press_event => sub { 
    my ($widget, $event) = @_;
    my ($x, $y) = ($event->x, $event->y);
    
    #convert UTM to Lat and Long
    my $easting = $ps[0] * $x + 0.0 * $y + $mtp[3];
    my $northing = (-$ps[1]) * $y + 0.0 * $x + $mtp[4];
    my ($latitude,$longitude)=utm_to_latlon($ellipsoid,$zone,$easting,$northing);
    print "$x, $y, ($latitude, $longitude)\n";
});

#Pack
$ebox->add($widget);
$vp->add($ebox);
$window->add($table);
$scwin->add($vp);
$table->attach_defaults($scwin, 0, 1, 0, 1);

#change the cursor over image
$ebox->realize;
$ebox->window->set_cursor(Gtk2::Gdk::Cursor->new ('hand2'));

$window->show_all;

Gtk2->main;