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package GPX::PlotElevation;
# ABSTRACT: create elevation graphs from GPX files


=head1 NAME
  
GPX::PlotElevation - a perl module for creating elevation graphs
  
=head1 SYNOPSIS

use GPX::PlotElevation;
    
my $plot = GPX::PlotElevation->new(
  'gpxfile' => $ARGV[0],
  'output' => 'transalp-2009.png',
  'width' => 40,
  'height' => 10,
);
$plot->calc();
$plot->plot();

=head1 FUNCTIONS

=cut

use strict;
use warnings;

our $VERSION = '1.01'; # VERSION

use IO::File;
use Geo::Gpx;
use Geo::Distance;
use Chart::Gnuplot;

sub new {
	my $invocant = shift();
	my $class = ref($invocant) || $invocant;

	my $self = {
		gpxfile => undef,
		gpxfh => undef,
		gpx => undef,
		title => "Hoehenprofil",
		xlabel => 'Entfernung [km]',
		ylabel => 'Hoehe [m]',
		output => undef,
		fileformat => 'png',
		width => 10,
		height => 7,
		formula => 'hsin',
		_points => [],
		_wp_points => [],
		_total_dist => 0,
		_gpx => undef,
		_geodist => Geo::Distance->new(),
		@_
	};
	bless($self, $class);

	$self->{'_geodist'}->formula($self->{'formula'});
	$self->_load_gpx();
	$self->fileformat($self->{'fileformat'});

	return($self);
}

sub fileformat {
	my $self = shift();
	my $fileformat = shift();

	if($fileformat !~ m/^(png)$/) {
		die("unsupported output fileformat: ".$fileformat);
	}
	$self->{'fileformat'} = $fileformat;
}

sub _load_gpx {
	my $self = shift();
	my $infh;

	if(defined $self->{'gpx'}) {
		$self->{'_gpx'} = Geo::Gpx->new( xml => $self->{'gpx'});
		return();
	}
	if(defined $self->{'gpxfile'}) {
		$infh = IO::File->new("<".$self->{'gpxfile'});
		$self->{'_gpx'} = Geo::Gpx->new( input => $infh );
		$infh->close();
		return();
	}
	if(defined $self->{'gpxfh'}) {
		$self->{'_gpx'} = Geo::Gpx->new( input => $self->{'gpxfh'} );
		return();
	}

	die('No GPX input given.');
}

=head2 calc()

Calculate the distance between points in tracks and assig
the waypoints to trackpoints.

=cut

sub calc {
	my $self = shift();

	$self->_calculate_distances();
	$self->_assign_waypoints();
}

sub _calculate_distances {
	my $self =  shift();
	my $tracks = $self->{'_gpx'}->tracks();
	my $dist;
	my $lastpoint = undef;

	foreach my $track (@$tracks) {
		my $segments = $track->{'segments'};