Introduction

This plugin provides support for the HTML5's geolocation feature. In 3 steps you will be able to add location based behaviour to your application. User's current position will be retrieved and put into the session. The Geolocation is representated by the Geolocation domain class which implements the official W3C specifications.

Usage

3 steps to make your app location based (assuming you are already using a Ajax lib like jquery or prototype) :

• grails install-plugin geolocation
• add the tag <geolocation:resources/> in the head section of your page you want to be location aware
• add the tag <geolocation:locateMe/> in the body section of your page

• Grails 1.3.x <geolocation:resourcesPrototype/> : If you add this line then you don't need to add <geolocation:resources/> line in your page. All you need is just one line. It will load json.js as well as the prototype.js library in your gsp page. It won't work in a Grails 2.0 app if you don't have prototype.js library located inside the js folder of your app.
• Grails 2.0.0 <geolocation:resourcesJquery/> : If you add this line then you don't need to add <geolocation:resources/> line in your page. All you need is just one line. It will load json.js as well as the jquery.js library in your gsp page.

• From a gsp (inside a javascript function) :

var latlng = new google.maps.LatLng(${session.position.coords.latitude},${session.position.coords.longitude});

• From a controller :

def position = session['position']

Once the user's location is known you can use the test page provided by the plugin to test it with a google map widget :

your_app_name/geolocation/showMap

Utility methods

• Calculate a distance

double distance = myPosition.distanceFrom(otherPosition)

• Check if your position is in a range

boolean isInRange = myPosition.isInRange(otherPosition,50) // check if the position is an range of 50 Km

These 2 methods are also available in the GeolocationService bean.

The default length unit is "KILOMETER" but you can configure it by setting in your config the following key :

geolocation.length.unit="MILE" //or KILOMETER, METER, NAUTIC_MILE

Browsers support

The geolocation feature is actually supported by :

• iPhone Safari
• Safari (5.0)
• Firefox (3.5 and above)

Domain classes

Geoposition.groovy

package org.grails.plugins.geolocation

import org.grails.plugins.geolocation.Coordinates;
class GeoPosition {
	Coordinates coords
	long timestamp
    static constraints = {
    }
}

Coordinates.groovy

package org.grails.plugins.geolocation
import org.grails.plugins.geolocation.GeoPosition;
class Coordinates {
GeoPosition position
    static constraints = {
      latitude(nullable:true)
      longitude(nullable:true)
      altitude(nullable:true)
      accuracy(nullable:true)
      altitudeAccuracy(nullable:true)
      heading(nullable:true)
      speed(nullable:true)
    }
    double latitude
    double longitude
    double altitude
    double accuracy
    double altitudeAccuracy
    double heading
    double speed 
 static belongsTo = GeoPosition
}

Source code

Source code is available at the the svn codehaus site but also on github :

http://github.com/sebastienblanc/geolocation