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.IX Title "Wiki::Toolkit::Plugin::Locator::Grid 3pm"
.TH Wiki::Toolkit::Plugin::Locator::Grid 3pm "2016-04-01" "perl v5.22.1" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
Wiki::Toolkit::Plugin::Locator::Grid \- A Wiki::Toolkit plugin to manage co\-ordinate data.
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
Access to and calculations using co-ordinate metadata supplied to a
Wiki::Toolkit wiki when writing a node.
.PP
\&\fBNote:\fR This is \fIread-only\fR access. If you want to write to a node's
metadata, you need to do it using the \f(CW\*(C`write_node\*(C'\fR method of
Wiki::Toolkit.
.PP
We assume that the points are located on a flat, square grid with unit
squares of side 1 metre.
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 2
\&  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",
\&                                                     );
.Ve
.SH "METHODS"
.IX Header "METHODS"
.IP "\fBnew\fR" 4
.IX Item "new"
.Vb 3
\&  # 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",
\&                                                     );
.Ve
.IP "\fBx_field\fR" 4
.IX Item "x_field"
.Vb 1
\&  my $x_field = $locator\->x_field;
.Ve
.Sp
An accessor, returns the name of the metadata field used to store the
x\-coordinate.
.IP "\fBy_field\fR" 4
.IX Item "y_field"
.Vb 1
\&  my $y_field = $locator\->y_field;
.Ve
.Sp
An accessor, returns the name of the metadata field used to store the
y\-coordinate.
.IP "\fBcoordinates\fR" 4
.IX Item "coordinates"
.Vb 1
\&  my ($x, $y) = $locator\->coordinates( node => "Jerusalem Tavern" );
.Ve
.Sp
Returns the x and y co-ordinates stored as metadata last time the node
was written.
.IP "\fBdistance\fR" 4
.IX Item "distance"
.Vb 3
\&  # 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" );
.Ve
.Sp
Defaults to metres if \f(CW\*(C`unit\*(C'\fR is not supplied or is not recognised.
Recognised units at the moment: \f(CW\*(C`metres\*(C'\fR, \f(CW\*(C`kilometres\*(C'\fR.
.Sp
Returns \f(CW\*(C`undef\*(C'\fR if one of the endpoints does not exist, or does not
have both co-ordinates defined. The \f(CW\*(C`node\*(C'\fR specification of an
endpoint overrides the x/y co-ords if both specified (but don't do
that).
.Sp
\&\fBNote:\fR Works to the nearest metre. Well, actually, calls \f(CW\*(C`int\*(C'\fR and
rounds down, but if anyone cares about that they can send a patch.
.IP "\fBfind_within_distance\fR" 4
.IX Item "find_within_distance"
.Vb 3
\&  # 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 );
.Ve
.Sp
Units currently understood: \f(CW\*(C`metres\*(C'\fR, \f(CW\*(C`kilometres\*(C'\fR. If both \f(CW\*(C`node\*(C'\fR
and \f(CW\*(C`x\*(C'\fR/\f(CW\*(C`y\*(C'\fR are supplied then \f(CW\*(C`node\*(C'\fR takes precedence. Croaks if
insufficient start point data supplied.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
.IP "\(bu" 4
Wiki::Toolkit
.IP "\(bu" 4
OpenGuides \- an application that uses this plugin.
.SH "AUTHOR"
.IX Header "AUTHOR"
Kake Pugh (kake@earth.li).
The Wiki::Toolkit team (http://www.wiki\-toolkit.org/)
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
.Vb 2
\&     Copyright (C) 2004 Kake L Pugh.  All Rights Reserved.
\&     Copyright (C) 2006 the Wiki::Toolkit Team. All Rights Reserved.
.Ve
.PP
This module is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
.SH "CREDITS"
.IX Header "CREDITS"
This module is based heavily on (and is the replacement for)
Wiki::Toolkit::Plugin::Locator::UK.
.PP
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 \f(CW\*(C`find_within_distance\*(C'\fR. Marcel Gruenauer
helped me make \f(CW\*(C`find_within_distance\*(C'\fR work properly with postgres.
.SH "POD ERRORS"
.IX Header "POD ERRORS"
Hey! \fBThe above document had some coding errors, which are explained below:\fR
.IP "Around line 269:" 4
.IX Item "Around line 269:"
You forgot a '=back' before '=head1'