fix: Add listener to enable equalizer when audioSessionId changes

app/src/degoogled/java/com/cappielloantonio/tempo/service/MediaService.kt

@@ -82,6 +82,7 @@ class MediaService : MediaLibraryService() {
         private const val CUSTOM_COMMAND_TOGGLE_REPEAT_MODE_ALL =
             "android.media3.session.demo.REPEAT_ALL"
         const val ACTION_BIND_EQUALIZER = "com.cappielloantonio.tempo.service.BIND_EQUALIZER"
+        const val ACTION_EQUALIZER_UPDATED = "com.cappielloantonio.tempo.service.EQUALIZER_UPDATED"
     }
 
     fun updateMediaItems() {
@@ -283,16 +284,7 @@ class MediaService : MediaLibraryService() {
     private fun initializeEqualizerManager() {
         equalizerManager = EqualizerManager()
         val audioSessionId = player.audioSessionId
-        if (equalizerManager.attachToSession(audioSessionId)) {
-            val enabled = Preferences.isEqualizerEnabled()
-            equalizerManager.setEnabled(enabled)
-
-            val bands = equalizerManager.getNumberOfBands()
-            val savedLevels = Preferences.getEqualizerBandLevels(bands)
-            for (i in 0 until bands) {
-                equalizerManager.setBandLevel(i.toShort(), savedLevels[i])
-            }
-        }
+        attachEqualizerIfPossible(audioSessionId)
     }
 
     private fun initializeMediaLibrarySession() {
@@ -426,6 +418,10 @@ class MediaService : MediaLibraryService() {
                 customLayout = librarySessionCallback.buildCustomLayout(player)
                 mediaLibrarySession.setCustomLayout(customLayout)
             }
+
+            override fun onAudioSessionIdChanged(audioSessionId: Int) {
+                attachEqualizerIfPossible(audioSessionId)
+            }
         })
         if (player.isPlaying) {
             scheduleWidgetUpdates()
@@ -541,6 +537,21 @@ class MediaService : MediaLibraryService() {
         widgetUpdateScheduled = false
     }
 
+    private fun attachEqualizerIfPossible(audioSessionId: Int): Boolean {
+        if (audioSessionId == 0 || audioSessionId == -1) return false
+        val attached = equalizerManager.attachToSession(audioSessionId)
+        if (attached) {
+            val enabled = Preferences.isEqualizerEnabled()
+            equalizerManager.setEnabled(enabled)
+            val bands = equalizerManager.getNumberOfBands()
+            val savedLevels = Preferences.getEqualizerBandLevels(bands)
+            for (i in 0 until bands) {
+                equalizerManager.setBandLevel(i.toShort(), savedLevels[i])
+            }
+            sendBroadcast(Intent(ACTION_EQUALIZER_UPDATED))
+        }
+        return attached
+    }
 
     private fun getRenderersFactory() = DownloadUtil.buildRenderersFactory(this, false)
 

app/src/main/java/com/cappielloantonio/tempo/ui/fragment/EqualizerFragment.kt

@@ -3,7 +3,9 @@ package com.cappielloantonio.tempo.ui.fragment
 import android.content.ComponentName
 import android.content.Context
 import android.content.Intent
+import android.content.IntentFilter
 import android.content.ServiceConnection
+import android.content.BroadcastReceiver
 import android.os.Bundle
 import android.os.IBinder
 import android.view.Gravity
@@ -12,6 +14,7 @@ import android.view.View
 import android.view.ViewGroup
 import android.widget.*
 import androidx.annotation.OptIn
+import androidx.core.content.ContextCompat
 import androidx.fragment.app.Fragment
 import androidx.media3.common.util.UnstableApi
 import com.cappielloantonio.tempo.R
@@ -28,6 +31,18 @@ class EqualizerFragment : Fragment() {
     private lateinit var safeSpace: Space
     private val bandSeekBars = mutableListOf<SeekBar>()
 
+    private var receiverRegistered = false
+    private val equalizerUpdatedReceiver = object : BroadcastReceiver() {
+        @OptIn(UnstableApi::class)
+        override fun onReceive(context: Context?, intent: Intent?) {
+            if (intent?.action == MediaService.ACTION_EQUALIZER_UPDATED) {
+                // Equalizer became available or updated. Rebuild UI and restore values.
+                initUI()
+                restoreEqualizerPreferences()
+            }
+        }
+    }
+
     private val connection = object : ServiceConnection {
         @OptIn(UnstableApi::class)
         override fun onServiceConnected(className: ComponentName, service: IBinder) {
@@ -49,12 +64,29 @@ class EqualizerFragment : Fragment() {
             intent.action = MediaService.ACTION_BIND_EQUALIZER
             requireActivity().bindService(intent, connection, Context.BIND_AUTO_CREATE)
         }
+        if (!receiverRegistered) {
+            ContextCompat.registerReceiver(
+                requireContext(),
+                equalizerUpdatedReceiver,
+                IntentFilter(MediaService.ACTION_EQUALIZER_UPDATED),
+                ContextCompat.RECEIVER_NOT_EXPORTED
+            )
+            receiverRegistered = true
+        }
     }
 
     override fun onStop() {
         super.onStop()
         requireActivity().unbindService(connection)
         equalizerManager = null
+        if (receiverRegistered) {
+            try {
+                requireContext().unregisterReceiver(equalizerUpdatedReceiver)
+            } catch (_: Exception) {
+                // ignore if not registered
+            }
+            receiverRegistered = false
+        }
     }
 
     override fun onCreateView(