Wiki::Toolkit::Plugin::Locator::Grid(3pm)		User Contributed Perl Documentation		 Wiki::Toolkit::Plugin::Locator::Grid(3pm)

NAME

       Wiki::Toolkit::Plugin::Locator::Grid - A Wiki::Toolkit plugin to manage co-ordinate data.

DESCRIPTION

       Access to and calculations using co-ordinate metadata supplied to a Wiki::Toolkit wiki when writing a node.

       Note: This is read-only access. If you want to write to a node's metadata, you need to do it using the "write_node" method of Wiki::Tool-
       kit.

       We assume that the points are located on a flat, square grid with unit squares of side 1 metre.

SYNOPSIS

	 use Wiki::Toolkit;
	 use Wiki::Toolkit::Plugin::Locator::Grid;

	 my $wiki = Wiki::Toolkit->new( ... );
	 my $locator = Wiki::Toolkit::Plugin::Locator::Grid->new;
	 $wiki->register_plugin( plugin => $locator );

	 $wiki->write_node( "Jerusalem Tavern", "A good pub", $checksum,
			    { x => 531674, y => 181950 } ) or die "argh";

	 # Just retrieve the co-ordinates.
	 my ( $x, $y ) = $locator->coordinates( node => "Jerusalem Tavern" );

	 # Find the straight-line distance between two nodes, in metres.
	 my $distance = $locator->distance( from_node => "Jerusalem Tavern",
					    to_node   => "Calthorpe Arms" );

	 # Find all the things within 200 metres of a given place.
	 my @others = $locator->find_within_distance( node   => "Albion",
						      metres => 200 );

	 # Maybe our wiki calls the x and y co-ordinates something else.
	 my $locator = Wiki::Toolkit::Plugin::Locator::Grid->new(
							      x => "os_x",
							      y => "os_y",
							    );

METHODS

       new
	     # By default we assume that x and y co-ordinates are stored in
	     # metadata called "x" and "y".
	     my $locator = Wiki::Toolkit::Plugin::Locator::Grid->new;

	     # But maybe our wiki calls the x and y co-ordinates something else.
	     my $locator = Wiki::Toolkit::Plugin::Locator::Grid->new(
								  x => "os_x",
								  y => "os_y",
								);

       x_field
	     my $x_field = $locator->x_field;

	   An accessor, returns the name of the metadata field used to store the x-coordinate.

       y_field
	     my $y_field = $locator->y_field;

	   An accessor, returns the name of the metadata field used to store the y-coordinate.

       coordinates
	     my ($x, $y) = $locator->coordinates( node => "Jerusalem Tavern" );

	   Returns the x and y co-ordinates stored as metadata last time the node was written.

       distance
	     # Find the straight-line distance between two nodes, in metres.
	     my $distance = $locator->distance( from_node => "Jerusalem Tavern",
						to_node   => "Calthorpe Arms" );

	     # Or in kilometres, and between a node and a point.
	     my $distance = $locator->distance( from_x	=> 531467,
						from_y	=> 183246,
						to_node => "Duke of Cambridge",
						unit	=> "kilometres" );

	   Defaults to metres if "unit" is not supplied or is not recognised.  Recognised units at the moment: "metres", "kilometres".

	   Returns "undef" if one of the endpoints does not exist, or does not have both co-ordinates defined. The "node" specification of an end-
	   point overrides the x/y co-ords if both specified (but don't do that).

	   Note: Works to the nearest metre. Well, actually, calls "int" and rounds down, but if anyone cares about that they can send a patch.

       find_within_distance
	     # Find all the things within 200 metres of a given place.
	     my @others = $locator->find_within_distance( node	 => "Albion",
							  metres => 200 );

	     # Or within 200 metres of a given location.
	     my @things = $locator->find_within_distance( x	 => 530774,
							  y	 => 182260,
							  metres => 200 );

	   Units currently understood: "metres", "kilometres". If both "node" and "x"/"y" are supplied then "node" takes precedence. Croaks if
	   insufficient start point data supplied.

SEE ALSO

	   * Wiki::Toolkit
	   * OpenGuides - an application that uses this plugin.

AUTHOR

       Kake Pugh (kake@earth.li).  The Wiki::Toolkit team (http://www.wiki-toolkit.org/)

COPYRIGHT

	    Copyright (C) 2004 Kake L Pugh.  All Rights Reserved.
	    Copyright (C) 2006 the Wiki::Toolkit Team. All Rights Reserved.

       This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

CREDITS

       This module is based heavily on (and is the replacement for) Wiki::Toolkit::Plugin::Locator::UK.

       The following thanks are due to people who helped with Wiki::Toolkit::Plugin::Locator::UK: Nicholas Clark found a very silly bug in a pre-
       release version, oops :) Stephen White got me thinking in the right way to implement "find_within_distance". Marcel Gruenauer helped me
       make "find_within_distance" work properly with postgres.

perl v5.8.8							    2007-10-23				 Wiki::Toolkit::Plugin::Locator::Grid(3pm)