1 /**

     2  * This class provides access to device accelerometer data.

     3  * @constructor

     4  */

     5 function Accelerometer() {

     6 	/**

     7 	 * The last known acceleration.

     8 	 */

     9 	this.lastAcceleration = null;

    10 }

    11 

    12 /**

    13  * Asynchronously aquires the current acceleration.

    14  * @param {Function} successCallback The function to call when the acceleration

    15  * data is available

    16  * @param {Function} errorCallback The function to call when there is an error 

    17  * getting the acceleration data.

    18  * @param {AccelerationOptions} options The options for getting the accelerometer data

    19  * such as timeout.

    20  */

    21 

    22 Accelerometer.prototype.getCurrentAcceleration = function(successCallback, errorCallback, options) {

    23 	// If the acceleration is available then call success

    24 	// If the acceleration is not available then call error

    25 	

    26 	try {

    27 		if (!this.serviceObj) 

    28 			this.serviceObj = this.getServiceObj();

    29 		

    30 		if (this.serviceObj == null) 

    31 			throw {

    32 				name: "DeviceErr",

    33 				message: "Could not initialize service object"

    34 			};

    35 		

    36 		//get the sensor channel

    37 		var SensorParams = {

    38 			SearchCriterion: "AccelerometerAxis"

    39 		};

    40 		var returnvalue = this.serviceObj.ISensor.FindSensorChannel(SensorParams);

    41 		var error = returnvalue["ErrorCode"];

    42 		var errmsg = returnvalue["ErrorMessage"];

    43 		if (!(error == 0 || error == 1012)) {

    44 			var ex = {

    45 				name: "Unable to find Sensor Channel: " + error,

    46 				message: errmsg

    47 			};

    48 			throw ex;

    49 		}

    50 		var channelInfoMap = returnvalue["ReturnValue"][0];

    51 		var criteria = {

    52 			ChannelInfoMap: channelInfoMap,

    53 			ListeningType: "ChannelData"

    54 		};

    55 		

    56 		if (typeof(successCallback) != 'function') 

    57 			successCallback = function(){

    58 			};

    59 		if (typeof(errorCallback) != 'function') 

    60 			errorCallback = function(){

    61 			};

    62 		

    63 		this.success_callback = successCallback;

    64 		this.error_callback = errorCallback;

    65 		//create a closure to persist this instance of Accelerometer into the RegisterForNofication callback

    66 		var obj = this;

    67 		

    68 		// TODO: this call crashes WRT, but there is no other way to read the accel sensor

    69 		// http://discussion.forum.nokia.com/forum/showthread.php?t=182151&highlight=memory+leak

    70 		this.serviceObj.ISensor.RegisterForNotification(criteria, function(transId, eventCode, result){

    71 			try {

    72 				var criteria = {

    73 					TransactionID: transId

    74 				};

    75 				obj.serviceObj.ISensor.Cancel(criteria);

    76 				

    77 				var accel = new Acceleration(result.ReturnValue.XAxisData, result.ReturnValue.YAxisData, result.ReturnValue.ZAxisData);

    78 				Accelerometer.lastAcceleration = accel;

    79 				

    80 				obj.success_callback(accel);

    81 				

    82 			} 

    83 			catch (ex) {

    84 				obj.serviceObj.ISensor.Cancel(criteria);

    85 				obj.error_callback(ex);

    86 			}

    87 			

    88 		});

    89 	} catch (ex) {

    90 		errorCallback(ex);

    91 	}

    92 

    93 };

    94 

    95 

    96 /**

    97  * Asynchronously aquires the acceleration repeatedly at a given interval.

    98  * @param {Function} successCallback The function to call each time the acceleration

    99  * data is available

   100  * @param {Function} errorCallback The function to call when there is an error 

   101  * getting the acceleration data.

   102  * @param {AccelerationOptions} options The options for getting the accelerometer data

   103  * such as timeout.

   104  */

   105 

   106 Accelerometer.prototype.watchAcceleration = function(successCallback, errorCallback, options) {

   107 	this.getCurrentAcceleration(successCallback, errorCallback, options);

   108 	// TODO: add the interval id to a list so we can clear all watches

   109  	var frequency = (options != undefined)? options.frequency : 10000;

   110 	return setInterval(function() {

   111 		navigator.accelerometer.getCurrentAcceleration(successCallback, errorCallback, options);

   112 	}, frequency);

   113 };

   114 

   115 /**

   116  * Clears the specified accelerometer watch.

   117  * @param {String} watchId The ID of the watch returned from #watchAcceleration.

   118  */

   119 Accelerometer.prototype.clearWatch = function(watchId) {

   120 	clearInterval(watchId);

   121 };

   122 

   123 //gets the Acceleration Service Object from WRT

   124 Accelerometer.prototype.getServiceObj = function() {

   125 	var so;

   126 	

   127     try {

   128         so = device.getServiceObject("Service.Sensor", "ISensor");

   129     } catch (ex) {

   130 		throw {

   131 			name: "DeviceError",

   132 			message: "Could not initialize accel service object (" + ex.name + ": " + ex.message + ")"

   133 		};

   134     }		

   135 	return so;

   136 };

   137 

   138 if (typeof navigator.accelerometer == "undefined") navigator.accelerometer = new Accelerometer();