playback: fix brief pause when adding songs to playlists

CHANGELOG.md

@@ -10,6 +10,7 @@
 - Sorting songs by date now uses songs date first, before the earliest album date
 
 #### What's Fixed
+- Playback no longer briefly pauses when adding songs to playlists 
 - Music loader no longer spawns thousands of threads when scanning
 - Excessive CPU no longer spent showing music loading process
 - Fixed playback sheet flickering on warm start

app/src/main/java/org/oxycblt/auxio/playback/service/ExoPlaybackStateHolder.kt

@@ -49,6 +49,7 @@ import org.oxycblt.auxio.music.Song
 import org.oxycblt.auxio.music.service.toMediaItem
 import org.oxycblt.auxio.music.service.toSong
 import org.oxycblt.auxio.playback.PlaybackSettings
+import org.oxycblt.auxio.playback.msToSecs
 import org.oxycblt.auxio.playback.persist.PersistenceRepository
 import org.oxycblt.auxio.playback.replaygain.ReplayGainAudioProcessor
 import org.oxycblt.auxio.playback.state.DeferredPlayback
@@ -365,13 +366,21 @@ class ExoPlaybackStateHolder(
     override fun applySavedState(
         parent: MusicParent?,
         rawQueue: RawQueue,
+        positionMs: Long,
+        repeatMode: RepeatMode,
         ack: StateAck.NewPlayback?
     ) {
-        logD("Applying saved state")
-        var sendEvent = false
+        val resolve = resolveQueue()
+        logD("${rawQueue.heap == resolve.heap}")
+        logD("${rawQueue.shuffledMapping == resolve.shuffledMapping}")
+        logD("${rawQueue.heapIndex == resolve.heapIndex}")
+        logD("${rawQueue.isShuffled == resolve.isShuffled}")
+        logD("${rawQueue == resolve}")
+        var sendNewPlaybackEvent = false
+        var shouldSeek = false
         if (this.parent != parent) {
             this.parent = parent
-            sendEvent = true
+            sendNewPlaybackEvent = true
         }
         if (rawQueue != resolveQueue()) {
             player.setMediaItems(rawQueue.heap.map { it.toMediaItem(context, null) })
@@ -384,9 +393,18 @@ class ExoPlaybackStateHolder(
             player.seekTo(rawQueue.heapIndex, C.TIME_UNSET)
             player.prepare()
             player.pause()
-            sendEvent = true
+            sendNewPlaybackEvent = true
+            shouldSeek = true
         }
-        if (sendEvent) {
+
+        repeatMode(repeatMode)
+        // Positions in milliseconds will drift during tight restores (i.e what the music loader
+        // does to sanitize the state), compare by seconds instead.
+        if (positionMs.msToSecs() != player.currentPosition.msToSecs() || shouldSeek) {
+            player.seekTo(positionMs)
+        }
+
+        if (sendNewPlaybackEvent) {
             ack?.let { playbackManager.ack(this, it) }
         }
     }

app/src/main/java/org/oxycblt/auxio/playback/state/PlaybackStateHolder.kt

@@ -145,7 +145,13 @@ interface PlaybackStateHolder {
      * @param ack The [StateAck] to return to [PlaybackStateManager]. If null, do not return any
      *   ack.
      */
-    fun applySavedState(parent: MusicParent?, rawQueue: RawQueue, ack: StateAck.NewPlayback?)
+    fun applySavedState(
+        parent: MusicParent?,
+        rawQueue: RawQueue,
+        positionMs: Long,
+        repeatMode: RepeatMode,
+        ack: StateAck.NewPlayback?
+    )
 
     /** End whatever ongoing playback session may be going on */
     fun endSession()

app/src/main/java/org/oxycblt/auxio/playback/state/PlaybackStateManager.kt

@@ -24,6 +24,7 @@ import org.oxycblt.auxio.list.adapter.UpdateInstructions
 import org.oxycblt.auxio.music.Music
 import org.oxycblt.auxio.music.MusicParent
 import org.oxycblt.auxio.music.Song
+import org.oxycblt.auxio.playback.state.PlaybackStateManager.Listener
 import org.oxycblt.auxio.util.logD
 import org.oxycblt.auxio.util.logW
 
@@ -416,9 +417,12 @@ class PlaybackStateManagerImpl @Inject constructor() : PlaybackStateManager {
 
         this.stateHolder = stateHolder
         if (isInitialized && currentSong != null) {
-            stateHolder.applySavedState(stateMirror.parent, stateMirror.rawQueue, null)
-            stateHolder.seekTo(stateMirror.progression.calculateElapsedPositionMs())
-            stateHolder.playing(false)
+            stateHolder.applySavedState(
+                stateMirror.parent,
+                stateMirror.rawQueue,
+                stateMirror.progression.calculateElapsedPositionMs(),
+                stateMirror.repeatMode,
+                null)
         }
         pendingDeferredPlayback?.let(stateHolder::handleDeferred)
     }
@@ -795,9 +799,12 @@ class PlaybackStateManagerImpl @Inject constructor() : PlaybackStateManager {
                         index
                     })
 
-        stateHolder.applySavedState(savedState.parent, rawQueue, StateAck.NewPlayback)
-        stateHolder.seekTo(savedState.positionMs)
-        stateHolder.repeatMode(savedState.repeatMode)
+        stateHolder.applySavedState(
+            savedState.parent,
+            rawQueue,
+            savedState.positionMs,
+            savedState.repeatMode,
+            StateAck.NewPlayback)
 
         isInitialized = true
     }