listening to volume events now override default behaviour

framework/assets/js/cordova.android.js

@@ -639,6 +639,9 @@ Channel.prototype.unsubscribe = function(g) {
     if (handler) {
         this.handlers[g] = null;
         delete this.handlers[g];
+    }
+    // useful when same handler has been set multiple times and already deleted
+    if (this.numHandlers > 0) {
         this.numHandlers--;
         if (this.events.onUnsubscribe) this.events.onUnsubscribe.call(this);
     }
@@ -1047,6 +1050,28 @@ module.exports = {
         cordova.addDocumentEventHandler('menubutton');
         cordova.addDocumentEventHandler('searchbutton');
 
+        function bindButtonChannel(buttonName) {
+            // generic button bind used for volumeup/volumedown buttons
+            return cordova.addDocumentEventHandler(buttonName + 'button', {
+                onSubscribe:function() {
+                    // If we just attached the first handler, let native know we need to override the button.
+                    if (this.numHandlers === 1) {
+                        exec(null, null, "App", "overrideButton", [buttonName, true]);
+                    }
+                },
+                onUnsubscribe:function() {
+                    // If we just detached the last handler, let native know we no longer override the volumeup button.
+                    if (this.numHandlers === 0) {
+                        exec(null, null, "App", "overrideButton", [buttonName, false]);
+                    }
+                }
+            });
+
+        }
+        // Inject a listener for the volume buttons on the document.
+        var volumeUpButtonChannel = bindButtonChannel('volumeup');
+        var volumeDownButtonChannel = bindButtonChannel('volumedown');
+
         // Figure out if we need to shim-in localStorage and WebSQL
         // support from the native side.
         var storage = require('cordova/plugin/android/storage');
@@ -3586,6 +3611,20 @@ module.exports = {
     exec(null, null, "App", "overrideBackbutton", [override]);
   },
 
+  /**
+   * Override the default behavior of the Android volume button.
+   * If overridden, when the volume button is pressed, the "volume[up|down]button" JavaScript event will be fired.
+   *
+   * Note: The user should not have to call this method.  Instead, when the user
+   *       registers for the "volume[up|down]button" event, this is automatically done.
+   *
+   * @param button          volumeup, volumedown
+   * @param override        T=override, F=cancel override
+   */
+  overrideButton:function(button, override) {
+    exec(null, null, "App", "overrideButton", [button, override]);
+  },
+
   /**
    * Exit and terminate the application.
    */

framework/src/org/apache/cordova/App.java

@@ -62,6 +62,9 @@ public class App extends Plugin {
             }
         	else if (action.equals("overrideBackbutton")) {
             	this.overrideBackbutton(args.getBoolean(0));
+            }
+            else if (action.equals("overrideButton")) {
+                this.overrideButton(args.getString(0), args.getBoolean(1));
             }
         	else if (action.equals("isBackbuttonOverridden")) {
             	boolean b = this.isBackbuttonOverridden();
@@ -180,6 +183,17 @@ public class App extends Plugin {
     	((DroidGap)this.ctx).bound = override;
     }
 
+    /**
+     * Override the default behavior of the Android volume buttons.
+     * If overridden, when the volume button is pressed, the "volume[up|down]button" JavaScript event will be fired.
+     *
+     * @param button        volumeup, volumedown
+     * @param override      T=override, F=cancel override
+     */
+    public void overrideButton(String button, boolean override) {
+        LOG.i("DroidGap", "WARNING: Volume Button Default Behaviour will be overridden.  The volume event will be fired!");
+        ((DroidGap)this.ctx).bindButton(button, override);
+    }
     /**
      * Return whether the Android back button is overridden by the user.
      * 

framework/src/org/apache/cordova/DroidGap.java

@@ -158,6 +158,8 @@ public class DroidGap extends Activity implements CordovaInterface {
 
     protected LinearLayout root;
     public boolean bound = false;
+    public boolean volumeupBound = false;
+    public boolean volumedownBound = false;
     public CallbackServer callbackServer;
     protected PluginManager pluginManager;
     protected boolean cancelLoadUrl = false;
@@ -1087,18 +1089,38 @@ public class DroidGap extends Activity implements CordovaInterface {
             return true;
         }
 
+        return false;
+    }
+
+    /**
+     * Called when a key is pressed. (Key DOWN)
+     *
+     * @param keyCode
+     * @param event
+     */
+    @Override
+    public boolean onKeyDown(int keyCode, KeyEvent event) {
+        if (this.appView == null) {
+            return super.onKeyDown(keyCode, event);
+        }
+
         // If volumedown key
-        else if (keyCode == KeyEvent.KEYCODE_VOLUME_DOWN) {
-            this.appView.loadUrl("javascript:cordova.fireDocumentEvent('volumedownbutton');");
-            return true;
+        if (keyCode == KeyEvent.KEYCODE_VOLUME_DOWN) {
+            if (this.volumedownBound==true) {
+                // only override default behaviour is event bound
+                this.appView.loadUrl("javascript:cordova.fireDocumentEvent('volumedownbutton');");
+                return true;
+            }
         }
 
         // If volumeup key
         else if (keyCode == KeyEvent.KEYCODE_VOLUME_UP) {
-            this.appView.loadUrl("javascript:cordova.fireDocumentEvent('volumeupbutton');");
-            return true;
+            if (this.volumeupBound==true) {
+                // only override default behaviour is event bound
+                this.appView.loadUrl("javascript:cordova.fireDocumentEvent('volumeupbutton');");
+                return true;
+            }
         }
-
         return false;
     }
 
@@ -1416,6 +1438,16 @@ public class DroidGap extends Activity implements CordovaInterface {
       return this.bound;
     }
 
+    public void bindButton(String button, boolean override) {
+      // TODO Auto-generated method stub
+      if (button.compareTo("volumeup")==0) {
+        this.volumeupBound = override;
+      }
+      else if (button.compareTo("volumedown")==0) {
+        this.volumedownBound = override;
+      }
+    }
+
     protected Dialog splashDialog;
     
     /**