Add changed event for volume and updated MpdSession to regcognise it.

mopidy/frontends/mpd/__init__.py

@@ -58,6 +58,9 @@ class MpdFrontend(actor.ThreadingActor, listeners.BackendListener):
     def options_changed(self):
         self.send_idle('options')
 
+    def volume_changed(self):
+        self.send_idle('mixer')
+
 
 class MpdSession(network.LineProtocol):
     """

mopidy/listeners.py

@@ -70,3 +70,11 @@ class BackendListener(object):
         *MAY* be implemented by actor.
         """
         pass
+
+    def volume_changed(self):
+        """
+        Called whenever the volume is changed.
+
+        *MAY* be implemented by actor.
+        """
+        pass

mopidy/mixers/base.py

@@ -1,4 +1,8 @@
-from mopidy import settings
+import logging
+
+from mopidy import listeners, settings
+
+logger = logging.getLogger('mopdy.mixers')
 
 class BaseMixer(object):
     """
@@ -30,6 +34,7 @@ class BaseMixer(object):
         elif volume > 100:
             volume = 100
         self.set_volume(volume)
+        self._trigger_volume_changed()
 
     def get_volume(self):
         """
@@ -46,3 +51,7 @@ class BaseMixer(object):
         *MUST be implemented by subclass.*
         """
         raise NotImplementedError
+
+    def _trigger_volume_changed(self):
+        logger.debug(u'Triggering volume changed event')
+        listeners.BackendListener.send('volume_changed')