NAME
Geo::JSON - Perl OO interface for geojson
SYNOPSIS
use Geo::JSON;
my $obj = Geo::JSON->from_json( $json );
$obj->to_json();
DESCRIPTION
Convert to and from geojson using Perl objects. GeoJSON objects
represent various geographical positions - points, lines, polygons, etc.
Currently supports 2 or 3 dimensions (longitude, latitude, altitude).
Further dimensions in positions are ignored for calculations and
comparisons, but will be read-from and written-to.
GEOJSON SPECIFICATION
See: <http://www.geojson.org/geojson-spec.html>
GEOJSON MEMBERS (ATTRIBUTES)
See the specification for the full details, but the basics are as
follows:
* "type"
Determines the object the json will be turned into
* "position"
Not explicitly named in the json, but an array of at least two
numbers representing a location in x, y, z order (either Easting,
Northing, Altitude or Longitude, Latitude, Altitude as appropriate).
Additional numbers may be present but ignored by this package for
calculations.
* "coordinates"
Defined in geometry objects (Point, MultiPoint, LineString,
MultiLineString, Polygon, MultiPolygon). Will consist of a single
position (Point), an array of positions (MultiPoint, LineString), an
array of arrays of positions (MultiLineString, Polygon) or an array
of arrays of arrays of positions (MultiPolygon). The positions
within a single object should all have the same number of axes and
be in the same axis order.
* "bbox"
Optional, defining a bounding box that the position(s) are contained
by.
The box is defined by a array of 2*n items, where n is the number of
dimensions in a position. The items are the lowest value for an axis
followed by the highest value for an axis, in the axis order used in
the positions.
The Co-ordinates Reference System for the bounding box is assumed to
match that of the object.
* "crs"
Optional, defining the Co-ordinates Reference System the object is
using. See Geo::JSON::CRS for more details.
GEOMETRY OBJECTS
* Geo::JSON::Point
A single position
* Geo::JSON::MultiPoint
An array of positions, representing multiple points
* Geo::JSON::LineString
An array of 2 or more positions, represening a connected line
* Geo::JSON::MultiLineString
An array of lines
* Geo::JSON::Polygon
An array of lines, defining a polygon. The first line represents the
outside of the polygon, subsequent lines define any 'holes'. The
lines must be 'linear rings' - 4 or more points, with the first and
last points being equivalent.
* Geo::JSON::MultiPolygon
An array of polygons
* Geo::JSON::GeometryCollection
An array of any of the above Geometry objects (as attribute
"geometries")
FEATURE OBJECTS
* Geo::JSON::Feature
Any of the above objects (as attribute "feature"), together with a
data structure (as attruibute "properties")
FEATURE COLLECTION OBJECTS
* Geo::JSON::FeatureCollection
An array of Feature objects (as attribute "features")
METHODS
from_json
my $obj = Geo::JSON->from_json( $json );
Takes a geojson string, returns the object it represents.
to_json
$obj->to_json();
$obj->to_json( $codec );
Call on a Geo::JSON object. Returns the JSON that represents the object.
Pass in an optional JSON codec to modify the default behaviour of the
JSON returned.
load
my $obj = Geo::JSON->load( { type => 'Point', coordinates => ... } );
Creates a Geo::JSON object from a hashref.
This is used for coercion of attributes during object creation, and
probably should not be called directly otherwise.
CLASS METHODS
codec
Geo::JSON->codec->canonical(1)->pretty;
my $prev_codec = Geo::JSON->codec($new_codec);
Set options on or replace JSON codec.
THANKS
Tim Bunce - for codec suggestions and bug spotting.
SEE ALSO
* Geo::JSON::Simple - simple interface to create Geo::JSON objects.
SUPPORT
Bugs / Feature Requests
Please report any bugs or feature requests through the issue tracker at
<https://github.com/mjemmeson/Geo-JSON/issues>. You will be notified
automatically of any progress on your issue.
Source Code
This is open source software. The code repository is available for
public review and contribution under the terms of the license.
<https://github.com/mjemmeson/Geo-JSON>
git clone https://github.com/mjemmeson/Geo-JSON.git
AUTHOR
Michael Jemmeson <mjemmeson@cpan.org>
COPYRIGHT AND LICENSE
This software is copyright (c) 2015 by Michael Jemmeson
<mjemmeson@cpan.org>.
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.