Media controls (MPRIS, Windows SMTC); stop old tracks when switching

Player.py

@@ -37,6 +37,9 @@ class Player:
         self.OnEnded: Callable[[], None] = lambda: None
         self.OnChanged: Callable[[], None] = lambda: None  # playing/paused, duration, source
         self.OnError: Callable[[str], None] = lambda Message: None
+        # Others following along (the system media controls): called with
+        # "Changed", "Started" or "Seeked" after the owner's own callbacks.
+        self.Watchers: list[Callable[[str], None]] = []
 
     # --- Position -----------------------------------------------------------
 
@@ -51,6 +54,12 @@ class Player:
         self._Position = max(0, int(Milliseconds))
         self._PositionAt = time.monotonic()
 
+    def _Tell(self, Kind: str) -> None:
+        if Kind == "Changed":
+            self.OnChanged()
+        for Watcher in self.Watchers:
+            Watcher(Kind)
+
     # --- Events from the client ---------------------------------------------
 
     def _StateChanged(self, Audio: fta.Audio, e: fta.AudioStateChangeEvent) -> None:
@@ -61,6 +70,7 @@ class Player:
                 self._SetPosition(self._Position)
                 self.Playing = True
                 self.OnStarted()
+                self._Tell("Started")
         elif e.state == fta.AudioState.COMPLETED:
             self.Playing = False
             self._SetPosition(0)
@@ -72,7 +82,7 @@ class Player:
             if self.Playing:
                 self._SetPosition(self.Position)
             self.Playing = False
-        self.OnChanged()
+        self._Tell("Changed")
 
     def _PositionChanged(self, Audio: fta.Audio, e: fta.AudioPositionChangeEvent) -> None:
         if Audio is self.Audio and self.Playing:
@@ -86,7 +96,7 @@ class Player:
         if Value > 0:
             self.Duration = Value
             self._Ready.set()
-            self.OnChanged()
+            self._Tell("Changed")
 
     def _Loaded(self, Audio: fta.Audio) -> None:
         if Audio is self.Audio:
@@ -109,9 +119,16 @@ class Player:
         Old, self.Audio = self.Audio, None
         if Old is None:
             return
+        # Taking a service off the page doesn't stop its native player: it
+        # would play on, unseen. Stop and free it first.
+        for Method in (Old.pause, Old.release):
+            try:
+                await asyncio.wait_for(Method(), 2)
+            except (asyncio.TimeoutError, RuntimeError):
+                pass
         if Old in self.Page.services:
             self.Page.services.remove(Old)
-            self.Page.update()  # disposes the old service and its native player
+            self.Page.update()
 
     async def Load(self, FilePath: str, Start: int = 0, Play: bool = True, Duration: int = 0) -> bool:
         """Switches to FilePath and (if Play) starts at Start (ms). Duration is
@@ -138,7 +155,7 @@ class Player:
         self.Audio = Audio
         self.Page.services.append(Audio)
         self.Page.update()
-        self.OnChanged()
+        self._Tell("Changed")
         if Play:
             return await self.Play(Start)
         return True
@@ -166,6 +183,7 @@ class Player:
             if not await self._Call(Audio.seek, ft.Duration(milliseconds=int(Position))):
                 return False
             self._SetPosition(Position)  # it played from 0 until the seek landed
+            self._Tell("Seeked")
             return True
         return await self._Call(Audio.play, ft.Duration(milliseconds=0))
 
@@ -174,7 +192,7 @@ class Player:
             self._SetPosition(self.Position)
             self.Playing = False
             await self._Call(self.Audio.pause)
-            self.OnChanged()
+            self._Tell("Changed")
 
     async def Toggle(self) -> None:
         if self.Playing:
@@ -193,7 +211,8 @@ class Player:
             await self._Call(self.Audio.seek, ft.Duration(milliseconds=Milliseconds))
         else:
             # Paused or not started: remember it, Play starts from there.
-            self.OnChanged()
+            self._Tell("Changed")
+        self._Tell("Seeked")
 
     async def Stop(self) -> None:
         """Back to nothing loaded."""
@@ -202,10 +221,11 @@ class Player:
         self.Playing = False
         self.Duration = 0
         self._SetPosition(0)
-        self.OnChanged()
+        self._Tell("Changed")
 
     def SetVolume(self, Volume: float) -> None:
         self.Volume = max(0.0, min(1.0, Volume))
         if self.Audio is not None:
             self.Audio.volume = self.Volume
             self.Audio.update()
+        self._Tell("Volume")