Geo-Google-PolylineEncoder

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README  view on Meta::CPAN

    The module is a port of Mark McClure's `PolylineEncoder.js' with some
    tweaks. The original can be found here:

    http://facstaff.unca.edu/mcmcclur/GoogleMaps/EncodePolyline/

CONSTRUCTOR & ACCESSORS
    new( [%args] )
        Create a new encoder. Arguments are optional and correspond to the
        accessor with the same name: the num_levels, zoom_factor,
        visible_threshold, and force_endpoints entries elsewhere in this
        document, etc...

        Note: there's nothing stopping you from setting these properties
        each time you encode a polyline.

    num_levels
        How many different levels of magnification the polyline has.
        Default: 18.

    zoom_factor
        The change in magnification between those levels (see num_levels).
        Default: 2.

    visible_threshold
        Indicates the length of a barely visible object at the highest zoom
        level. Default: 0.00001. err.. units.

    force_endpoints
        Indicates whether or not the endpoints should be visible at all zoom
        levels. force_endpoints is. Probably should stay true regardless.
        Default: 1=true.

    escape_encoded_points
        Indicates whether or not the encoded points should have escape
        characters escaped, eg:

          $points =~ s/\\/\\\\/g;

        This is useful if you'll be evalling the resulting strings, or
        copying them into a static document.

lib/Geo/Google/PolylineEncoder.pm  view on Meta::CPAN

  };
  var line = GPolyline.fromEncoded( opts );

=cut

package Geo::Google::PolylineEncoder;

use strict;
use warnings;

use accessors qw(num_levels zoom_factor visible_threshold force_endpoints
		 zoom_level_breaks escape_encoded_points lons_first
		 points dists max_dist encoded_points encoded_levels );
use constant defaults => {
			  num_levels  => 18,
			  zoom_factor => 2,
			  force_endpoints => 1,
			  escape_encoded_points => 0,
			  visible_threshold => 0.00001,
			  lons_first => 0,
			 };
our $VERSION = 0.06;

# The constructor
sub new {
    my $class = shift;
    my $self = bless {}, $class;

lib/Geo/Google/PolylineEncoder.pm  view on Meta::CPAN

    my $max_dist = $self->max_dist;

    # Cache for performance:
    my $num_levels = $self->num_levels;
    my $num_levels_minus_1 = $num_levels - 1;
    my $visible_threshold = $self->visible_threshold;
    my $zoom_level_breaks = $self->zoom_level_breaks;

    my $encoded_levels = "";

    if ($self->force_endpoints) {
	$encoded_levels .= $self->encode_number($num_levels_minus_1);
    } else {
	$encoded_levels .= $self->encode_number($num_levels_minus_1 - $self->compute_level($max_dist));
    }


    # Note: skip the first & last point:
    for my $i (1 .. scalar(@$points) - 2) {
	my $dist = $dists->[$i];
	if (defined $dist) {

lib/Geo/Google/PolylineEncoder.pm  view on Meta::CPAN

	    if ($dist > $visible_threshold) {
		while ($dist < $zoom_level_breaks->[$level]) {
		    $level++;
		}
	    }

	    $encoded_levels .= $self->encode_number($num_levels_minus_1 - $level);
	}
    }

    if ($self->force_endpoints) {
	$encoded_levels .= $self->encode_number($num_levels_minus_1);
    } else {
	$encoded_levels .= $self->encode_number($num_levels_minus_1 - $self->compute_level($max_dist));
    }

    $self->encoded_levels( $encoded_levels );
}


# This computes the appropriate zoom level of a point in terms of it's

lib/Geo/Google/PolylineEncoder.pm  view on Meta::CPAN

L<http://facstaff.unca.edu/mcmcclur/GoogleMaps/EncodePolyline/>

=head1 CONSTRUCTOR & ACCESSORS

=over 4

=item new( [%args] )

Create a new encoder.  Arguments are optional and correspond to the accessor
with the same name: L</num_levels>, L</zoom_factor>, L</visible_threshold>,
L</force_endpoints>, etc...

Note: there's nothing stopping you from setting these properties each time you
L</encode> a polyline.

=item num_levels

How many different levels of magnification the polyline has.
Default: 18.

=item zoom_factor

The change in magnification between those levels (see L</num_levels>).
Default: 2.

=item visible_threshold

Indicates the length of a barely visible object at the highest zoom level.
Default: 0.00001.  err.. units.

=item force_endpoints

Indicates whether or not the endpoints should be visible at all zoom levels.
force_endpoints is.  Probably should stay true regardless.
Default: 1=true.

=item escape_encoded_points

Indicates whether or not the encoded points should have escape characters
escaped, eg:

  $points =~ s/\\/\\\\/g;

This is useful if you'll be evalling the resulting strings, or copying them into