[gnome-music/wip/jfelder/mpris-cleanup: 3/13] mpris: Do not send PlaybackStatus property if unchanged

[Jean Felder <jfelder src gnome org>]

commit be6b7d15ee7ba9fdd0f56992c4022e144e060094
Author: Jean Felder <jfelder src gnome org>
Date:   Wed Mar 20 11:27:09 2019 +0100

    mpris: Do not send PlaybackStatus property if unchanged
    
    GstPlayer state changes can be redundant because of its asynchronous
    nature. For example, when launching a new song, the playing state is
    sent two times. This results in the PlaybackStatus "Playing" property
    being sent two times.
    
    Checking  that the status has really changed to avoid sending two
    times the same signal.
    
    Related: #43

 gnomemusic/mpris.py | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)
---
diff --git a/gnomemusic/mpris.py b/gnomemusic/mpris.py
index aaaf685e..d5716f6f 100644
--- a/gnomemusic/mpris.py
+++ b/gnomemusic/mpris.py
@@ -271,6 +271,7 @@ class MPRIS(DBusInterface):
         self._player_previous_type = None
         self._path_list = []
         self._metadata_list = []
+        self._previous_playback_status = "Stopped"
 
     @log
     def _get_playback_status(self):
@@ -465,9 +466,14 @@ class MPRIS(DBusInterface):
 
     @log
     def _on_player_state_changed(self, klass, args):
+        playback_status = self._get_playback_status()
+        if playback_status == self._previous_playback_status:
+            return
+
+        self._previous_playback_status = playback_status
         self.PropertiesChanged(MPRIS.MEDIA_PLAYER2_PLAYER_IFACE,
                                {
-                                   'PlaybackStatus': GLib.Variant('s', self._get_playback_status()),
+                                   'PlaybackStatus': GLib.Variant('s', playback_status),
                                },
                                [])