BackgroundGeoLocation
==============================

Cross-platform background geolocation for Cordova with battery-saving "circular region monitoring" and "stop detection".

Follows the [Cordova Plugin spec](https://github.com/apache/cordova-plugman/blob/master/plugin_spec.md), so that it works with [Plugman](https://github.com/apache/cordova-plugman).

This plugin leverages Cordova/PhoneGap's [require/define functionality used for plugins](http://simonmacdonald.blogspot.ca/2012/08/so-you-wanna-write-phonegap-200-android.html).

## Using the plugin ##
The plugin creates the object `window.plugins.backgroundGeoLocation` with the methods

  `configure(success, fail, option)`,

  `start(success, fail)`

  `stop(success, fail)`.

  `changePace(true) // engages aggressive monitoring immediately  (eg "begin workout" for a jogging app) `

## Installing the plugin ##

```

   cordova plugin add https://github.com/christocracy/cordova-background-geolocation.git
```

A full example could be:
```
    //
    //
    // after deviceready
    //
    //

    // Your app must execute AT LEAST ONE call for the current position via standard Cordova geolocation,
    //  in order to prompt the user for Location permission.
    window.navigator.geolocation.getCurrentPosition(function(location) {
        console.log('Location from Phonegap');
    });

    var bgGeo = window.plugins.backgroundGeoLocation;

    /**
    * This would be your own callback for Ajax-requests after POSTing background geolocation to your server.
    */
    var yourAjaxCallback = function(response) {
        ////
        // IMPORTANT:  You must execute the #finish method here to inform the native plugin that you're finished,
        //  and the background-task may be completed.  You must do this regardless if your HTTP request is successful or not.
        // IF YOU DON'T, ios will CRASH YOUR APP for spending too much time in the background.
        //
        //
        bgGeo.finish();
    };

    /**
    * This callback will be executed every time a geolocation is recorded in the background.
    */
    var callbackFn = function(location) {
        console.log('[js] BackgroundGeoLocation callback:  ' + location.latitude + ',' + location.longitude);
        // Do your HTTP request here to POST location to your server.
        //
        //
        yourAjaxCallback.call(this);
    };

    var failureFn = function(error) {
        console.log('BackgroundGeoLocation error');
    }

    // BackgroundGeoLocation is highly configurable.
    bgGeo.configure(callbackFn, failureFn, {
        desiredAccuracy: 0,                         // <-- 0:  highest power, highest accuracy; 1000:  lowest power, lowest accuracy.
        stationaryRadius: 50,
        distanceFilter: 50,                         // <-- minimum distance between location events
        activityType: 'AutomotiveNavigation',       // <-- [ios]
        locationUpdateInterval: 30000,              // <-- [android] minimum time between location updates, used in conjunction with #distanceFilter
        activityRecognitionInterval: 10000,         // <-- [android] sampling-rate activity-recognition system for movement/stationary detection
        debug: true,                                // <-- enable this hear sounds, see notifications during life-cycle events.
        stopOnTerminate: false                      // <-- enable this to clear background location settings when the app terminates
    });

    // Turn ON the background-geolocation system.  The user will be tracked whenever they suspend the app.
    bgGeo.start();

    // If you wish to turn OFF background-tracking, call the #stop method.
    // bgGeo.stop()


```

NOTE: The plugin includes `org.apache.cordova.geolocation` as a dependency.  You must enable Cordova's GeoLocation in the foreground and have the user accept Location services by executing `#watchPosition` or `#getCurrentPosition`.

## Example Application

This plugin hosts a SampleApp in ```example/SampleApp``` folder.  This SampleApp contains no plugins so you must first start by adding this plugin.  **NOTE** In order to use the SampleApp, it's important to make a copy of it outside of the plugin itself.

```
$ git clone git@github.com:christocracy/cordova-background-geolocation.git
$ mkdir tmp
$ cp -R cordova-background-geolocation/example/SampleApp tmp
$ cd tmp/SampleApp
$ cordova plugin add git@github.com:christocracy/cordova-background-geolocation.git
$ cordova platform add ios
$ cordova platform add android
$ cordova build ios
$ cordova build android

```

If you're using XCode, boot the SampleApp in the iOS Simulator and enable ```Debug->Location->City Drive```.


## Behaviour

The plugin has features allowing you to control the behaviour of background-tracking, striking a balance between accuracy and battery-usage.  In stationary-mode, the plugin attempts to descrease its power usage and accuracy by setting up a circular stationary-region of configurable #stationaryRadius.  iOS has a nice system  [Significant Changes API](https://developer.apple.com/library/ios/documentation/CoreLocation/Reference/CLLocationManager_Class/CLLocationManager/CLLocationManager.html#//apple_ref/occ/instm/CLLocationManager/startMonitoringSignificantLocationChanges), which allows the os to suspend your app until a cell-tower change is detected (typically 2-3 city-block change) Android uses the Google Play Services APIs [FusedLocationProvider API](https://developer.android.com/reference/com/google/android/gms/location/FusedLocationProviderApi.html) as well as the [ActivityRecognition API](https://developer.android.com/reference/com/google/android/gms/location/ActivityRecognitionApi.html) (for movement/stationary detection). Windows Phone does not have such a API.

The plugin will execute your configured ```callback``` provided to the ```#configure(callback, config)``` method. You must manually POST the received ```GeoLocation``` to your server using standard XHR, as well as manually cache a recieved location into ```localStorage``` if no network connection is available.

The function ```changePace(isMoving, success, failure)``` is provided to force the plugin to enter "moving" or "stationary" state.

## iOS

The plugin uses iOS Significant Changes API, and starts triggering your configured ```callback``` only when a cell-tower switch is detected (i.e. the device exits stationary radius). 

When the plugin detects the device has moved beyond its configured #stationaryRadius, it engages the native platform's geolocation system for aggressive monitoring according to the configured `#desiredAccuracy`, `#distanceFilter`.  The plugin attempts to intelligently scale `#distanceFilter` based upon the current reported speed.  Each time `#distanceFilter` is determined to have changed by 5m/s, it recalculates it by squaring the speed rounded-to-nearest-five and adding #distanceFilter (I arbitrarily came up with that formula.  Better ideas?).

  `(round(speed, 5))^2 + distanceFilter`

### Android

Using the [ActivityRecognition API](https://developer.android.com/reference/com/google/android/gms/location/ActivityRecognitionApi.html) provided by [Google Play Services](https://developer.android.com/google/play-services/index.html), Android will constantly monitor [the nature](https://developer.android.com/reference/com/google/android/gms/location/DetectedActivity.html) of the device's movement at a sampling-rate configured by ```#activityRecognitionRate```.  When the plugin sees a DetectedActivity of [STILL](https://developer.android.com/reference/com/google/android/gms/location/DetectedActivity.html), location-updates will be halted -- when it sees ```IN_VEHICLE, ON_BICYCLE, ON_FOOT, RUNNING, WALKING```, location-updates will be initiated.


### WP8

WP8 uses ```callbackFn``` the way iOS do. On WP8, however, the plugin does not support the Stationary location and does not implement ```getStationaryLocation()``` and ```onPaceChange()```.
Keep in mind that it is **not** possible to use ```start()``` at the ```pause``` event of Cordova/PhoneGap. WP8 suspend your app immediately and ```start()``` will not be executed. So make sure you fire ```start()``` before the app is closed/minimized.

### Config

Use the following config-parameters with the #configure method:

#####`@param {Integer} desiredAccuracy [0, 10, 100, 1000] in meters`

Specify the desired-accuracy of the geolocation system with 1 of 4 values, ```0, 10, 100, 1000``` where ```0``` means HIGHEST POWER, HIGHEST ACCURACY and ```1000``` means LOWEST POWER, LOWEST ACCURACY

- [Android](https://developer.android.com/reference/com/google/android/gms/location/LocationRequest.html#PRIORITY_BALANCED_POWER_ACCURACY)
- [iOS](https://developer.apple.com/library/ios/documentation/CoreLocation/Reference/CLLocationManager_Class/index.html#//apple_ref/occ/instp/CLLocationManager/desiredAccuracy) 

#####`@param {Integer} stationaryRadius (meters)`

When stopped, the minimum distance the device must move beyond the stationary location for aggressive background-tracking to engage.  Note, since the plugin uses iOS significant-changes API, the plugin cannot detect the exact moment the device moves out of the stationary-radius.  In normal conditions, it can take as much as 3 city-blocks to 1/2 km before staionary-region exit is detected.

#####`@param {Boolean} debug`

When enabled, the plugin will emit sounds for life-cycle events of background-geolocation!  **NOTE iOS**:  In addition, you must manually enable the *Audio and Airplay* background mode in *Background Capabilities* to hear these debugging sounds.

- Exit stationary region:  *[ios]* Calendar event notification sound *[android]* dialtone beep-beep-beep
- GeoLocation recorded:  *[ios]* SMS sent sound, *[android]* tt short beep, *[WP8]* High beep, 1 sec.
- Aggressive geolocation engaged:  *[ios]* SIRI listening sound, *[android]* none
- Passive geolocation engaged:  *[ios]* SIRI stop listening sound, *[android]* none
- Acquiring stationary location sound: *[ios]* "tick,tick,tick" sound, *[android]* none
- Stationary location acquired sound:  *[ios]* "bloom" sound, *[android]* long tt beep.

![Enable Background Audio](/enable-background-audio.png "Enable Background Audio")

#####`@param {Integer} distanceFilter`

The minimum distance (measured in meters) a device must move horizontally before an update event is generated.  @see [Apple docs](https://developer.apple.com/library/ios/documentation/CoreLocation/Reference/CLLocationManager_Class/CLLocationManager/CLLocationManager.html#//apple_ref/occ/instp/CLLocationManager/distanceFilter).  However, #distanceFilter is elastically auto-calculated by the plugin:  When speed increases, #distanceFilter increases;  when speed decreases, so does distanceFilter.

distanceFilter is calculated as the square of speed-rounded-to-nearest-5 and adding configured #distanceFilter.

  `(round(speed, 5))^2 + distanceFilter`

For example, at biking speed of 7.7 m/s with a configured distanceFilter of 30m:

  `=> round(7.7, 5)^2 + 30`
  `=> (10)^2 + 30`
  `=> 100 + 30`
  `=> 130`

A gps location will be recorded each time the device moves 130m.

At highway speed of 30 m/s with distanceFilter: 30,

  `=> round(30, 5)^2 + 30`
  `=> (30)^2 + 30`
  `=> 900 + 30`
  `=> 930`

A gps location will be recorded every 930m

Note the following real example of background-geolocation on highway 101 towards San Francisco as the driver slows down as he runs into slower traffic (geolocations become compressed as distanceFilter decreases)

![distanceFilter at highway speed](/distance-filter-highway.png "distanceFilter at highway speed")

Compare now background-geolocation in the scope of a city.  In this image, the left-hand track is from a cab-ride, while the right-hand track is walking speed.

![distanceFilter at city scale](/distance-filter-city.png "distanceFilter at city scale")

#####`@param {Boolean} stopOnTerminate`
Enable this in order to force a stop() when the application terminated (e.g. on iOS, double-tap home button, swipe away the app)


### Android Config

#####`@param {Integer millis} locationUpdateInterval`

Set the desired interval for active location updates, in milliseconds.

The location client will actively try to obtain location updates for your application at this interval, so it has a direct influence on the amount of power used by your application. Choose your interval wisely.

This interval is inexact. You may not receive updates at all (if no location sources are available), or you may receive them slower than requested. You may also receive them faster than requested (if other applications are requesting location at a faster interval). 

Applications with only the coarse location permission may have their interval silently throttled.

An interval of 0 is allowed, but not recommended, since location updates may be extremely fast on future implementations.

#####`@param {Integer millis} activityRecognitionInterval`

the desired time between activity detections. Larger values will result in fewer activity detections while improving battery life. A value of 0 will result in activity detections at the fastest possible rate.

### iOS Config

#####`@param {String} activityType [AutomotiveNavigation, OtherNavigation, Fitness, Other]`

Presumably, this affects ios GPS algorithm.  See [Apple docs](https://developer.apple.com/library/ios/documentation/CoreLocation/Reference/CLLocationManager_Class/CLLocationManager/CLLocationManager.html#//apple_ref/occ/instp/CLLocationManager/activityType) for more information

### WP8 Config

#####`{Integer [0, 10, 100, 1000]} desiredAccuracy`

###### Windows Phone
The underlying GeoLocator you can choose to use 'DesiredAccuracy' or 'DesiredAccuracyInMeters'. Since this plugins default configuration accepts meters, the default desiredAccuracy is mapped to the Windows Phone DesiredAccuracyInMeters leaving the DesiredAccuracy enum empty. For more info see the [MS docs](http://msdn.microsoft.com/en-us/library/windows/apps/windows.devices.geolocation.geolocator.desiredaccuracyinmeters) for more information.

## Licence ##

The MIT License

Copyright (c) 2013 Chris Scott, [Transistor Software](http://transistorsoft.com)

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
