Pode ser tarde demais para você, mas vou responder de qualquer maneira, com uma resposta semelhante à que dei a essa pergunta relacionada , para que futuros visitantes possam consultar as duas perguntas.
Eu não armazenaria esses valores na tabela de metadados de postagem, ou pelo menos não apenas lá. Você quer uma tabela com post_id, lat, loncolunas, então você pode colocar um índice delat, lon e consulta sobre isso. Não deve ser muito difícil manter-se atualizado com um gancho após salvar e atualizar.
Ao consultar o banco de dados, você define uma caixa delimitadora em torno do ponto inicial, para poder fazer uma consulta eficiente para todos os lat, lonpares entre as bordas norte-sul e leste-oeste da caixa.
Depois de obter esse resultado reduzido, é possível fazer um cálculo de distância mais avançado (direções de direção circulares ou reais) para filtrar os locais que estão nos cantos da caixa delimitadora e, portanto, mais longe do que você deseja.
Aqui você encontra um exemplo de código simples que funciona na área de administração. Você precisa criar a tabela extra de banco de dados. O código é ordenado do mais para o menos interessante.
<?php
/*
Plugin Name: Monkeyman geo test
Plugin URI: http://www.monkeyman.be
Description: Geolocation test
Version: 1.0
Author: Jan Fabry
*/
class Monkeyman_Geo
{
public function __construct()
{
add_action('init', array(&$this, 'registerPostType'));
add_action('save_post', array(&$this, 'saveLatLon'), 10, 2);
add_action('admin_menu', array(&$this, 'addAdminPages'));
}
/**
* On post save, save the metadata in our special table
* (post_id INT, lat DECIMAL(10,5), lon DECIMAL (10,5))
* Index on lat, lon
*/
public function saveLatLon($post_id, $post)
{
if ($post->post_type != 'monkeyman_geo') {
return;
}
$lat = floatval(get_post_meta($post_id, 'lat', true));
$lon = floatval(get_post_meta($post_id, 'lon', true));
global $wpdb;
$result = $wpdb->replace(
$wpdb->prefix . 'monkeyman_geo',
array(
'post_id' => $post_id,
'lat' => $lat,
'lon' => $lon,
),
array('%s', '%F', '%F')
);
}
public function addAdminPages()
{
add_management_page( 'Quick location generator', 'Quick generator', 'edit_posts', __FILE__ . 'generator', array($this, 'doGeneratorPage'));
add_management_page( 'Location test', 'Location test', 'edit_posts', __FILE__ . 'test', array($this, 'doTestPage'));
}
/**
* Simple test page with a location and a distance
*/
public function doTestPage()
{
if (!array_key_exists('search', $_REQUEST)) {
$default_lat = ini_get('date.default_latitude');
$default_lon = ini_get('date.default_longitude');
echo <<<EOF
<form action="" method="post">
<p>Center latitude: <input size="10" name="center_lat" value="{$default_lat}"/>
<br/>Center longitude: <input size="10" name="center_lon" value="{$default_lon}"/>
<br/>Max distance (km): <input size="5" name="max_distance" value="100"/></p>
<p><input type="submit" name="search" value="Search!"/></p>
</form>
EOF;
return;
}
$center_lon = floatval($_REQUEST['center_lon']);
$center_lat = floatval($_REQUEST['center_lat']);
$max_distance = floatval($_REQUEST['max_distance']);
var_dump(self::getPostsUntilDistanceKm($center_lon, $center_lat, $max_distance));
}
/**
* Get all posts that are closer than the given distance to the given location
*/
public static function getPostsUntilDistanceKm($center_lon, $center_lat, $max_distance)
{
list($north_lat, $east_lon, $south_lat, $west_lon) = self::getBoundingBox($center_lat, $center_lon, $max_distance);
$geo_posts = self::getPostsInBoundingBox($north_lat, $east_lon, $south_lat, $west_lon);
$close_posts = array();
foreach ($geo_posts as $geo_post) {
$post_lat = floatval($geo_post->lat);
$post_lon = floatval($geo_post->lon);
$post_distance = self::calculateDistanceKm($center_lat, $center_lon, $post_lat, $post_lon);
if ($post_distance < $max_distance) {
$close_posts[$geo_post->post_id] = $post_distance;
}
}
return $close_posts;
}
/**
* Select all posts ids in a given bounding box
*/
public static function getPostsInBoundingBox($north_lat, $east_lon, $south_lat, $west_lon)
{
global $wpdb;
$sql = $wpdb->prepare('SELECT post_id, lat, lon FROM ' . $wpdb->prefix . 'monkeyman_geo WHERE lat < %F AND lat > %F AND lon < %F AND lon > %F', array($north_lat, $south_lat, $west_lon, $east_lon));
return $wpdb->get_results($sql, OBJECT_K);
}
/* Geographical calculations: distance and bounding box */
/**
* Calculate the distance between two coordinates
* http://stackoverflow.com/questions/365826/calculate-distance-between-2-gps-coordinates/1416950#1416950
*/
public static function calculateDistanceKm($a_lat, $a_lon, $b_lat, $b_lon)
{
$d_lon = deg2rad($b_lon - $a_lon);
$d_lat = deg2rad($b_lat - $a_lat);
$a = pow(sin($d_lat/2.0), 2) + cos(deg2rad($a_lat)) * cos(deg2rad($b_lat)) * pow(sin($d_lon/2.0), 2);
$c = 2 * atan2(sqrt($a), sqrt(1-$a));
$d = 6367 * $c;
return $d;
}
/**
* Create a box around a given point that extends a certain distance in each direction
* http://www.colorado.edu/geography/gcraft/warmup/aquifer/html/distance.html
*
* @todo: Mind the gap at 180 degrees!
*/
public static function getBoundingBox($center_lat, $center_lon, $distance_km)
{
$one_lat_deg_in_km = 111.321543; // Fixed
$one_lon_deg_in_km = cos(deg2rad($center_lat)) * 111.321543; // Depends on latitude
$north_lat = $center_lat + ($distance_km / $one_lat_deg_in_km);
$south_lat = $center_lat - ($distance_km / $one_lat_deg_in_km);
$east_lon = $center_lon - ($distance_km / $one_lon_deg_in_km);
$west_lon = $center_lon + ($distance_km / $one_lon_deg_in_km);
return array($north_lat, $east_lon, $south_lat, $west_lon);
}
/* Below this it's not interesting anymore */
/**
* Generate some test data
*/
public function doGeneratorPage()
{
if (!array_key_exists('generate', $_REQUEST)) {
$default_lat = ini_get('date.default_latitude');
$default_lon = ini_get('date.default_longitude');
echo <<<EOF
<form action="" method="post">
<p>Number of posts: <input size="5" name="post_count" value="10"/></p>
<p>Center latitude: <input size="10" name="center_lat" value="{$default_lat}"/>
<br/>Center longitude: <input size="10" name="center_lon" value="{$default_lon}"/>
<br/>Max distance (km): <input size="5" name="max_distance" value="100"/></p>
<p><input type="submit" name="generate" value="Generate!"/></p>
</form>
EOF;
return;
}
$post_count = intval($_REQUEST['post_count']);
$center_lon = floatval($_REQUEST['center_lon']);
$center_lat = floatval($_REQUEST['center_lat']);
$max_distance = floatval($_REQUEST['max_distance']);
list($north_lat, $east_lon, $south_lat, $west_lon) = self::getBoundingBox($center_lat, $center_lon, $max_distance);
add_action('save_post', array(&$this, 'setPostLatLon'), 5);
$precision = 100000;
for ($p = 0; $p < $post_count; $p++) {
self::$currentRandomLat = mt_rand($south_lat * $precision, $north_lat * $precision) / $precision;
self::$currentRandomLon = mt_rand($west_lon * $precision, $east_lon * $precision) / $precision;
$location = sprintf('(%F, %F)', self::$currentRandomLat, self::$currentRandomLon);
$post_data = array(
'post_status' => 'publish',
'post_type' => 'monkeyman_geo',
'post_content' => 'Point at ' . $location,
'post_title' => 'Point at ' . $location,
);
var_dump(wp_insert_post($post_data));
}
}
public static $currentRandomLat = null;
public static $currentRandomLon = null;
/**
* Because I didn't know how to save meta data with wp_insert_post,
* I do it here
*/
public function setPostLatLon($post_id)
{
add_post_meta($post_id, 'lat', self::$currentRandomLat);
add_post_meta($post_id, 'lon', self::$currentRandomLon);
}
/**
* Register a simple post type for us
*/
public function registerPostType()
{
register_post_type(
'monkeyman_geo',
array(
'label' => 'Geo Location',
'labels' => array(
'name' => 'Geo Locations',
'singular_name' => 'Geo Location',
'add_new' => 'Add new',
'add_new_item' => 'Add new location',
'edit_item' => 'Edit location',
'new_item' => 'New location',
'view_item' => 'View location',
'search_items' => 'Search locations',
'not_found' => 'No locations found',
'not_found_in_trash' => 'No locations found in trash',
'parent_item_colon' => null,
),
'description' => 'Geographical locations',
'public' => true,
'exclude_from_search' => false,
'publicly_queryable' => true,
'show_ui' => true,
'menu_position' => null,
'menu_icon' => null,
'capability_type' => 'post',
'capabilities' => array(),
'hierarchical' => false,
'supports' => array(
'title',
'editor',
'custom-fields',
),
'register_meta_box_cb' => null,
'taxonomies' => array(),
'permalink_epmask' => EP_PERMALINK,
'rewrite' => array(
'slug' => 'locations',
),
'query_var' => true,
'can_export' => true,
'show_in_nav_menus' => true,
)
);
}
}
$monkeyman_Geo_instance = new Monkeyman_Geo();