geo.php

<?php
/*
+--------------------------------------------------------------------------
|   WeCenter [#RELEASE_VERSION#]
|   ========================================
|   by WeCenter Software
|   © 2011 - 2014 WeCenter. All Rights Reserved
|   http://www.wecenter.com
|   ========================================
|   Support: WeCenter@qq.com
|
+---------------------------------------------------------------------------
*/


if (!defined('IN_ANWSION'))
{
	die;
}

define('GEO_EARTH_RADIUS', 6378);	// 地球半径

class geo_class extends AWS_MODEL
{
	/**
	* 计算某个经纬度的周围某段距离的正方形的四个点
	*
	* @param longitude float 经度
	* @param latitude float 纬度
	* @param radius float 该点所在圆的半径,该圆与此正方形内切, 单位: 千米
	* @return array 正方形的四个点的经纬度坐标
	*/
	public function get_square_point($longitude, $latitude, $radius = 1)
	{
		$target_longitude = rad2deg((2 * asin(sin($radius / (2 * GEO_EARTH_RADIUS)) / cos(deg2rad($latitude)))));

		$target_latitude = rad2deg(($radius / GEO_EARTH_RADIUS));

		return array(
			'TL' => array('latitude' => $latitude + $target_latitude, 'longitude' => $longitude - $target_longitude),	// Top left point
			//'TR' => array('latitude' => $latitude + $target_latitude, 'longitude' => $longitude + $target_longitude),	// Top right point
			//'BL' => array('latitude' => $latitude - $target_latitude, 'longitude' => $longitude - $target_longitude),	// Bottom left point
			'BR' => array('latitude' => $latitude - $target_latitude, 'longitude' => $longitude + $target_longitude)	// Bottom right point
		);
	}

	public function set_location($item_type, $item_id, $longitude, $latitude)
	{
		$this->delete('geo_location', "`item_type` = '" . $this->quote($item_type) . "' AND `item_id` = " . intval($item_id));

		return $this->insert('geo_location', array(
			'item_type' => $item_type,
			'item_id' => intval($item_id),
			'longitude' => $longitude,
			'latitude' => $latitude,
			'add_time' => time()
		));
	}

	public function get_distance($lon1, $lat1, $lon2, $lat2)
	{
		$theta = $lon1 - $lon2;
		$dist = sin(deg2rad($lat1)) * sin(deg2rad($lat2)) +  cos(deg2rad($lat1)) * cos(deg2rad($lat2)) * cos(deg2rad($theta));
		$dist = acos($dist);
		$dist = rad2deg($dist);
		$miles = $dist * 60 * 1.1515;

		return ($miles * 0.8684);
	}
}