Accelerometer updates:

- Removed thread delay to get accelerometer values.
- Override Activity lifecycle methods to manage JavaScript timers and enable window.onunload to be called.  This is needed for accelerometer to shut down correctly.

framework/assets/js/accelerometer.js

@@ -10,22 +10,41 @@ function Acceleration(x, y, z) {
  * @constructor
  */
 function Accelerometer() {
+
     /**
      * The last known acceleration.  type=Acceleration()
      */
     this.lastAcceleration = null;
+
     /**
      * List of accelerometer watch listeners
      */
     this.accelListeners = {};
+
     /**
      * List of accelerometer watch timers
      */
     this.accelTimers = {};
+
     /**
      * Next id to use
      */
     this.listenerId = 0;
+
+    /**
+     * Timer that turns off accelerometer when it reaches maximum time.
+     * This timer is only used for getCurrentAcceleration.
+     */
+    this.turnOffTimer = 0;
+
+    // Turn off accelerometer if not accessed for certain amount of time
+    setInterval(function() {
+        navigator.accelerometer.turnOffTimer += 10;
+        if (navigator.accelerometer.turnOffTimer > Accelerometer.MAX_TIMER) {
+            Accel.stop("timer");
+            navigator.accelerometer.turnOffTimer = 0;
+        }
+    }, 10000);
 }
 
 Accelerometer.STOPPED = 0;
@@ -35,14 +54,17 @@ Accelerometer.ERROR_FAILED_TO_START = 3;
 Accelerometer.ERROR_NOT_FOUND = 4;
 Accelerometer.ERROR_MSG = ["Not running", "Starting", "", "Failed to start", "Listener not found"];
 
+/**
+ * Time (in seconds) to turn off accelerometer if getCurrentAcceleration() hasn't been called.
+ */
+Accelerometer.MAX_TIMER = 30;
+
 /**
  * Asynchronously aquires the current acceleration.
- * @param {Function} successCallback The function to call when the acceleration
+ *
- * data is available
+ * @param {Function} successCallback    The function to call when the acceleration data is available
- * @param {Function} errorCallback The function to call when there is an error
+ * @param {Function} errorCallback      The function to call when there is an error getting the acceleration data.
- * getting the acceleration data.
+ * @param {AccelerationOptions} options The options for getting the accelerometer data such as timeout.
- * @param {AccelerationOptions} options The options for getting the accelerometer data
- * such as timeout.
  */
 Accelerometer.prototype.getCurrentAcceleration = function(successCallback, errorCallback, options) {
 
@@ -58,13 +80,13 @@ Accelerometer.prototype.getCurrentAcceleration = function(successCallback, error
         return;
     }
 
-    // Get current acceleration from native
+    // Get current acceleration status
     var status = Accel.getStatus();
-    //console.log("getCurrentAcceleration: status="+status);
 
     // If running, then call successCallback
     if (status == Accelerometer.RUNNING) {
         try {
+            navigator.accelerometer.turnOffTimer = 0;
             var accel = new Acceleration(Accel.getX(), Accel.getY(), Accel.getZ());
             successCallback(accel);
         } catch (e) {
@@ -74,29 +96,27 @@ Accelerometer.prototype.getCurrentAcceleration = function(successCallback, error
 
     // If not running, then start it
     else {
+        Accel.start("timer");
+        navigator.accelerometer.turnOffTimer = 0;
+        var obj = this;
 
-        Accel.start();
+        // Wait until started
+        var timer = setInterval(function() {
+            var status = Accel.getStatus();
+            if (status != Accelerometer.STARTING) {
+                clearInterval(timer);
 
-        var status = Accel.getStatus();
+                // If accelerometer is running
-        //console.log("getAcceleration: status="+status);
+                if (status == Accelerometer.RUNNING) {
+                    try {
+                        var accel = new Acceleration(Accel.getX(), Accel.getY(), Accel.getZ());
+                        successCallback(accel);
+                    } catch (e) {
+                        console.log("Accelerometer Error in successCallback: " + e);
+                    }
+                }
 
-        // Wait until sensor has 1 reading
+                // If accelerometer error
-        if (status == Accelerometer.STARTING) {
-            Accel.getX();
-            status = Accel.getStatus(); // get status again to see if started or error
-        }
-
-        // If sensor is running
-        if (status == Accelerometer.RUNNING) {
-            try {
-                var accel = new Acceleration(Accel.getX(), Accel.getY(), Accel.getZ());
-                successCallback(accel);
-            } catch (e) {
-                console.log("Accelerometer Error in successCallback: " + e);
-            }
-        }
-
-        // If sensor error
         else {
             console.log("Accelerometer Error: "+ Accelerometer.ERROR_MSG[status]);
             try {
@@ -107,24 +127,21 @@ Accelerometer.prototype.getCurrentAcceleration = function(successCallback, error
                 console.log("Accelerometer Error in errorCallback: " + e);
             }
         }
-
+            }
-        //@todo: don't clear now, wait until x seconds since last request
+        }, 10);
-        this.clearWatch("");
     }
 }
 
 /**
  * Asynchronously aquires the acceleration repeatedly at a given interval.
  *
- * @param {Function} successCallback The function to call each time the acceleration
+ * @param {Function} successCallback    The function to call each time the acceleration data is available
- * data is available
+ * @param {Function} errorCallback      The function to call when there is an error getting the acceleration data.
- * @param {Function} errorCallback The function to call when there is an error
+ * @param {AccelerationOptions} options The options for getting the accelerometer data such as timeout.
- * getting the acceleration data.
+ * @return String                       The watch id that must be passed to #clearWatch to stop watching.
- * @param {AccelerationOptions} options The options for getting the accelerometer data
- * such as timeout.
  */
 Accelerometer.prototype.watchAcceleration = function(successCallback, errorCallback, options) {
-
+    // Default interval (10 sec)
     var frequency = (options != undefined)? options.frequency : 10000;
 
     // successCallback required
@@ -139,33 +156,29 @@ Accelerometer.prototype.watchAcceleration = function(successCallback, errorCallb
         return;
     }
 
-    var key = this.listenerId++;
+    var id = ""+(navigator.accelerometer.listenerId++);
-    this.accelListeners[key] = key;
+    navigator.accelerometer.accelListeners[id] = id;
-    var obj = this;
+    Accel.start(id);
-    Accel.start();
 
     // Start watch timer
-    this.accelTimers[key] = setInterval(function() {
+    navigator.accelerometer.accelTimers[id] = setInterval(function() {
-        //console.log("Interval timer: key="+key+"  timer="+obj.accelTimers[key]+" freq="+frequency);
         var status = Accel.getStatus();
-        //console.log("watchAcceleration: status="+status);
 
+        // If accelerometer is running
         if (status == Accelerometer.RUNNING) {
             try {
-                // If getCurrentAcceleration(), then clear this watch
-                if (frequency == 0) {
-                    obj.clearWatch(key);
-                }
                 var accel = new Acceleration(Accel.getX(), Accel.getY(), Accel.getZ());
                 successCallback(accel);
             } catch (e) {
                 console.log("Accelerometer Error in successCallback: " + e);
             }
         }
-        else {
+
+        // If accelerometer had error
+        else if (status != Accelerometer.STARTING) {
             console.log("Accelerometer Error: "+ Accelerometer.ERROR_MSG[status]);
             try {
-                obj.clearWatch(key);
+                navigator.accelerometer.clearWatch(id);
                 if (errorCallback) {
                     errorCallback(status);
                 }
@@ -175,35 +188,33 @@ Accelerometer.prototype.watchAcceleration = function(successCallback, errorCallb
         }
     }, (frequency ? frequency : 1));
 
-    return key;
+    return id;
 }
 
 /**
  * Clears the specified accelerometer watch.
  *
- * @param {String} watchId The ID of the watch returned from #watchAcceleration.
+ * @param {String} id       The id of the watch returned from #watchAcceleration.
  */
-Accelerometer.prototype.clearWatch = function(watchId) {
+Accelerometer.prototype.clearWatch = function(id) {
 
     // Stop javascript timer & remove from timer list
-    if (watchId && this.accelTimers[watchId]) {
+    if (id && navigator.accelerometer.accelTimers[id]) {
-        clearInterval(this.accelListeners[watchId]);
+        clearInterval(navigator.accelerometer.accelTimers[id]);
-        delete this.accelTimers[watchId];
+        delete navigator.accelerometer.accelTimers[id];
     }
 
     // Remove from watch list
-    if (watchId && this.accelListeners[watchId]) {
+    if (id && navigator.accelerometer.accelListeners[id]) {
-        delete this.accelListeners[watchId];
+        delete navigator.accelerometer.accelListeners[id];
     }
 
-    // Stop native sensor if no more listeners
+    // Stop accelerometer for this watch listener
-    var size = 0;
+    if (id) {
-    var key;
+        try {
-    for (key in this.accelListeners) {
+            Accel.stop(id);
-        if (this.accelListeners.hasOwnProperty(key)) size++;
+        } catch (e) {
-    }
+        }
-    if (size == 0) {
-        Accel.stop();
     }
 }
 

framework/src/com/phonegap/AccelBroker.java

@@ -1,20 +1,16 @@
 package com.phonegap;
 
+import java.util.HashMap;
+
 import android.content.Context;
 import android.webkit.WebView;
 
 /**
  * This class manages access to the accelerometer from JavaScript.
  * One, free running accelerometer listener is created.  
- * It's state is controlled by start() and stop().
+ * It's state is controlled by start(id) and stop(id).
  * JavaScript is responsible for starting, stopping, and retrieving status and values.
- * 
+ * When all listener ids that were started are stopped, the accelerometer listener is stopped.
- * Since there may be some delay between starting and the first available value, when
- * retrieving values from JavaScript, the thread sleeps until the first value is 
- * received or until 1 sec elapses.
- * 
- * @author bcurtis
- *
  */
 public class AccelBroker {
 
@@ -27,6 +23,7 @@ public class AccelBroker {
     private WebView mAppView;								// WebView object
     private Context mCtx;									// Activity (DroidGap) object
     private AccelListener listener;							// Accelerator listener
+    private HashMap<String,Integer> listenerIds;			// List of listener ids
 
     /**
      * Constructor
@@ -41,15 +38,21 @@ public class AccelBroker {
 
         // Create listener
        	listener = new AccelListener(mCtx, mAppView);
+       	
+       	listenerIds = new HashMap<String,Integer>();
     }
 
     /**
      * Start listening to acceleration sensor.
      * 
-     * @return		true if started, false if not
+     * @param String id		The id of the listener
+     * @return				true if started, false if not
      */
-    public boolean start()
+    public boolean start(String id)
-    {        
+    {     
+    	// Track start for listener
+    	listenerIds.put(id, 1);
+    	
         // Start listener if necessary
         if ((listener.status != AccelBroker.RUNNING) && (listener.status != AccelBroker.STARTING)) {
         	listener.start();
@@ -61,33 +64,31 @@ public class AccelBroker {
     /**
      * Stop listening for acceleration sensor.
      * 
-     * @return 		true if stopped, false if not
+     * @param String id		The id of the listener
+     * @return 				true if stopped, false if not
      */
-    public boolean stop()
+    public boolean stop(String id)
-    {
+    {   	
-        listener.stop();
+    	// Stop tracking listener
-        return (listener.status == AccelBroker.STOPPED);
+    	if (listenerIds.containsKey(id)) {
+    		listenerIds.remove(id);
+    	}
+    	
+    	// If no more listeners, then stop accelerometer
+    	if (listenerIds.isEmpty()) {
+    		listener.stop();
+    	}
+    	
+    	return (listener.status == AccelBroker.STOPPED);
     }
     
     /**
-     * Wait until sensor is done starting up.
+     * Destroy listener
-     * If a request for values is made while sensor is still starting, then delay thread until first reading is made.
      */
-    void waitToStart() {
+    public void destroy() {
-       	if (listener.status == AccelBroker.STARTING) {
+    	listener.destroy();
-       		System.out.println("AccelBroker.waitToStart...");
-    		long timeout = 1000; // wait at most 1 sec
-    		while ((listener.status == AccelBroker.STARTING) && (timeout > 0)) {
-    			try {
-    				Thread.sleep(10);
-    				timeout = timeout - 10;
-    			}
-    			catch (InterruptedException e) {
-    			}
-    		}
-    	}
     }
-    
+        
     /**
      * Get result of the last request or update if watching.
      * If sensor is still starting, wait until 1st value is acquired before returning.
@@ -98,10 +99,7 @@ public class AccelBroker {
      * @return 			String representation of JSON object 
      */
     public String getResult() {
-    	
+    	        	
-    	// Wait for startup
-       	this.waitToStart();
-        	
        	// If acceleration values
        	if (listener.status == AccelBroker.RUNNING) {
        		return "{status:" + listener.status + ",value:{x:" + listener.x + ", y:" + listener.y + ", z:" + listener.z + "}}";
@@ -122,34 +120,28 @@ public class AccelBroker {
         
     /**
      * Get X value of last accelerometer value.
-     * If sensor is still starting, wait until 1st value is acquired before returning.
      * 
      * @return			x value
      */
     public float getX() {
-       	this.waitToStart();
    		return listener.x;
     }
     
     /**
      * Get Y value of last accelerometer value.
-     * If sensor is still starting, wait until 1st value is acquired before returning.
      * 
      * @return			y value
      */
     public float getY() {
-       	this.waitToStart();
    		return listener.y;
 	}
 
     /**
      * Get Z value of last accelerometer value.
-     * If sensor is still starting, wait until 1st value is acquired before returning.
      * 
      * @return			z value
      */
     public float getZ() {
-       	this.waitToStart();
    		return listener.x;
 	}
 

framework/src/com/phonegap/AccelListener.java

@@ -1,6 +1,5 @@
 package com.phonegap;
 
-
 import java.util.List;
 
 import android.hardware.Sensor;
@@ -10,6 +9,10 @@ import android.hardware.SensorManager;
 import android.content.Context;
 import android.webkit.WebView;
 
+/**
+ * This class listens to the accelerometer sensor and stores the latest 
+ * acceleration values x,y,z.
+ */
 public class AccelListener implements SensorEventListener{
 
     WebView mAppView;					// WebView object
@@ -53,7 +56,7 @@ public class AccelListener implements SensorEventListener{
         // If found, then register as listener
         if ((list != null) && (list.size() > 0)) {
             this.mSensor = list.get(0);
-            this.sensorManager.registerListener(this, this.mSensor, SensorManager.SENSOR_DELAY_UI); //SENSOR_DELAY_FASTEST);
+            this.sensorManager.registerListener(this, this.mSensor, SensorManager.SENSOR_DELAY_FASTEST);
             this.status = AccelBroker.STARTING;
         }
         
@@ -70,10 +73,18 @@ public class AccelListener implements SensorEventListener{
      */
     public void stop() {
         if (this.status == AccelBroker.RUNNING) {
-        	this.sensorManager.unregisterListener(this);	// unregister listener
+        	this.sensorManager.unregisterListener(this);
         }
         this.status = AccelBroker.STOPPED;
     }
+    
+    /**
+     * Called by AccelBroker when listener is to be shut down.
+     * Stop listener.
+     */
+    public void destroy() {
+    	this.sensorManager.unregisterListener(this);    	
+    }
 
     public void onAccuracyChanged(Sensor sensor, int accuracy) {
         // TODO Auto-generated method stub
@@ -85,17 +96,19 @@ public class AccelListener implements SensorEventListener{
      * @param SensorEvent event
      */
     public void onSensorChanged(SensorEvent event) {
+    	
     	// Only look at accelerometer events
         if (event.sensor.getType() != Sensor.TYPE_ACCELEROMETER) {
             return;
         }
-        this.status = AccelBroker.RUNNING;
         
         // Save time that event was received
         this.timeStamp = System.currentTimeMillis();
         this.x = event.values[0];
         this.y = event.values[1];
         this.z = event.values[2];            
+
+        this.status = AccelBroker.RUNNING;
     }
 
 }

framework/src/com/phonegap/DroidGap.java

@@ -139,11 +139,54 @@ public class DroidGap extends Activity {
 	}
 	
 	@Override
+    /**
+     * Called by the system when the device configuration changes while your activity is running. 
+     * 
+     * @param Configuration newConfig
+     */
     public void onConfigurationChanged(Configuration newConfig) {
       //don't reload the current page when the orientation is changed
       super.onConfigurationChanged(newConfig);
     } 
+
+    @Override
+    /**
+     * Called when the system is about to start resuming a previous activity. 
+     */
+    protected void onPause(){
+        super.onPause();
+        
+        // Pause JavaScript timers (including setInterval)
+        appView.pauseTimers();
+    }
+
+    @Override
+    /**
+     * Called when the activity will start interacting with the user. 
+     */
+    protected void onResume(){
+        super.onResume();
+        
+        // Resume JavaScript timers (including setInterval)
+        appView.resumeTimers();
+    }
     
+    @Override
+    /**
+     * The final call you receive before your activity is destroyed. 
+     */
+    public void onDestroy() {
+    	super.onDestroy();
+    	
+    	// Load blank page so that JavaScript onunload is called
+    	appView.loadUrl("about:blank");
+    	    	
+    	// Clean up objects
+    	if (accel != null) {
+    		accel.destroy();
+    	}
+    }
+
     private void bindBrowser(WebView appView)
     {
     	gap = new Device(appView, this);