speaker view

@@ -10,8 +10,11 @@ import androidx.appcompat.app.AppCompatActivity
 import androidx.recyclerview.widget.LinearLayoutManager
 import com.github.ajalt.timberkt.Timber
 import com.snakydesign.livedataextensions.combineLatest
+import com.snakydesign.livedataextensions.scan
+import com.snakydesign.livedataextensions.take
 import com.xwray.groupie.GroupieAdapter
-import io.livekit.android.room.track.LocalVideoTrack
+import io.livekit.android.room.participant.Participant
+import io.livekit.android.room.track.VideoTrack
 import io.livekit.android.sample.databinding.CallActivityBinding
 import kotlinx.parcelize.Parcelize
 
@@ -68,15 +71,26 @@ class CallActivity : AppCompatActivity() {
             }
 
         // speaker view setup
-        viewModel.room.observe(this) { room ->
+        viewModel.room.take(1).observe(this) { room ->
             room.initVideoRenderer(binding.speakerView)
-            val videoTrack = room.localParticipant.videoTracks.values
-                .firstOrNull()
-                ?.track as? LocalVideoTrack
-
-            videoTrack?.let {
-                it.addRenderer(binding.speakerView)
-            }
+            viewModel.activeSpeaker
+                .scan(Pair<Participant?, Participant?>(null, null)) { pair, participant ->
+                    // old participant is first
+                    // latest active participant is second
+                    Pair(pair.second, participant)
+                }.observe(this) { (oldSpeaker, newSpeaker) ->
+                    // Remove any renderering from the old speaker
+                    oldSpeaker?.videoTracks
+                        ?.values
+                        ?.forEach { trackPublication ->
+                            (trackPublication.track as? VideoTrack)?.removeRenderer(binding.speakerView)
+                        }
+
+                    val videoTrack = newSpeaker?.videoTracks?.values
+                        ?.firstOrNull()
+                        ?.track as? VideoTrack
+                    videoTrack?.addRenderer(binding.speakerView)
+                }
         }
 
         // Controls setup

@@ -12,6 +12,7 @@ import io.livekit.android.events.RoomEvent
 import io.livekit.android.events.collect
 import io.livekit.android.room.Room
 import io.livekit.android.room.participant.Participant
+import io.livekit.android.room.participant.RemoteParticipant
 import io.livekit.android.room.track.CameraPosition
 import io.livekit.android.room.track.LocalVideoTrack
 import io.livekit.android.room.track.Track
@@ -81,13 +82,18 @@ class CallViewModel(
     }
 
     private fun updateParticipants(room: Room) {
-        mutableParticipants.postValue(
-            listOf(room.localParticipant) +
-                    room.remoteParticipants
-                        .keys
-                        .sortedBy { it }
-                        .mapNotNull { room.remoteParticipants[it] }
-        )
+
+        val participantList = listOf(room.localParticipant) +
+                room.remoteParticipants
+                    .keys
+                    .sortedBy { it }
+                    .mapNotNull { room.remoteParticipants[it] }
+        mutableParticipants.postValue(participantList)
+
+        if (!participantList.contains(mutableActiveSpeaker.value) || mutableActiveSpeaker.value == null) {
+            // active speaker has left, choose someone else at random.
+            mutableActiveSpeaker.postValue(participantList.last())
+        }
     }
 
     fun handleActiveSpeakersChanged(speakers: List<Participant>) {
@@ -95,7 +101,9 @@ class CallViewModel(
         if (speakers.isEmpty() || speakers.contains(mutableActiveSpeaker.value)) {
             return
         }
-        val newSpeaker = speakers.firstOrNull() ?: return
+        val newSpeaker = speakers
+            .filter { it is RemoteParticipant } // Try not to display local participant as speaker.
+            .firstOrNull() ?: return
         mutableActiveSpeaker.postValue(newSpeaker)
     }