Add Seeked signal to Mpris interface

The Mpris2 spec includes a `Seeked` signal which should be fired when
the track position changes in an unexpected way i.e. when the user
seeks to a different part of the track.

This PR implements this signal on seek events and also when a new track
begins. The latter is not strictly required but has been observed in
other players (e.g. VLC).

Closes #1492

src/mpris.rs

@@ -6,6 +6,7 @@ use std::time::Duration;
 use tokio::sync::mpsc;
 use tokio_stream::wrappers::UnboundedReceiverStream;
 use tokio_stream::StreamExt;
+use zbus::object_server::SignalContext;
 use zbus::zvariant::{ObjectPath, Value};
 use zbus::{interface, ConnectionBuilder};
 
@@ -314,6 +315,9 @@ impl MprisPlayer {
         self.queue.get_current().is_some()
     }
 
+    #[zbus(signal)]
+    async fn seeked(context: &SignalContext<'_>, position: &i64) -> Result<(), zbus::Error>;
+
     fn next(&self) {
         self.queue.next(true)
     }
@@ -468,6 +472,8 @@ pub enum MprisCommand {
     NotifyPlaybackUpdate,
     /// Notify about volume updates.
     NotifyVolumeUpdate,
+    /// Notify about seek changes,
+    NotifySeekedUpdate(i64),
 }
 
 /// An MPRIS server that internally manager a thread which can be sent commands. This is internally
@@ -533,6 +539,11 @@ impl MprisManager {
                     info!("sending MPRIS volume update signal");
                     player_iface.volume_changed(ctx).await?;
                 }
+                Some(MprisCommand::NotifySeekedUpdate(pos)) => {
+                    // let pos = player_iface.position();
+                    info!("sending MPRIS seeked signal");
+                    MprisPlayer::seeked(ctx, &pos).await?;
+                }
                 None => break,
             }
         }

src/queue.rs

@@ -332,6 +332,10 @@ impl Queue {
                     move || send_notification(&summary_txt, &body_txt, cover_url)
                 });
             }
+
+            // Send a Seeked signal at start of new track
+            #[cfg(feature = "mpris")]
+            self.spotify.notify_seeked(0);
         }
 
         if reshuffle && self.get_shuffle() {

src/spotify.rs

@@ -394,6 +394,8 @@ impl Spotify {
     /// Seek in the currently played [Playable] played by the [Player].
     pub fn seek(&self, position_ms: u32) {
         self.send_worker(WorkerCommand::Seek(position_ms));
+        #[cfg(feature = "mpris")]
+        self.notify_seeked(position_ms);
     }
 
     /// Seek relatively to the current playback position of the [Player].
@@ -408,6 +410,17 @@ impl Spotify {
         self.cfg.state().volume
     }
 
+    /// Send a Seeked signal on Mpris interface
+    #[cfg(feature = "mpris")]
+    pub fn notify_seeked(&self, position: u32) {
+        if let Some(mpris_manager) = self.mpris.lock().unwrap().as_ref() {
+            info!("Seeked event");
+            // Mpris spec requires microseconds
+            let new_position = position * 1000;
+            mpris_manager.send(MprisCommand::NotifySeekedUpdate(new_position.into()));
+        }
+    }
+
     /// Set the current volume of the [Player]. If `notify` is true, also notify MPRIS clients about
     /// the update.
     pub fn set_volume(&self, volume: u16, notify: bool) {