playback: expose media button receiver

Expose a custom MediaButtonReceiver that handles the media button
intent. This is not because I wanted to implement this. Some apps
like gadgetbridge just blindly query ACTION_MEDIA_BUTTON instead of
relying on the more modern MediaController API, which I expected
most apps would use instead.

Resolves #62.

.gitignore

@@ -3,7 +3,7 @@
 local.properties
 build/
 release/
-deps/
+srclibs/
 
 # Studio
 .idea/

app/src/main/AndroidManifest.xml

@@ -50,8 +50,11 @@
             </intent-filter>
         </activity>
 
+        <!--
+        Workaround to get apps that blindly query for apps handling media buttons working
+        -->
         <receiver
-            android:name="androidx.media.session.MediaButtonReceiver"
+            android:name=".playback.system.MediaButtonReceiver"
             android:exported="true">
             <intent-filter>
                 <action android:name="android.intent.action.MEDIA_BUTTON" />
@@ -62,16 +65,8 @@
             android:name=".playback.system.PlaybackService"
             android:foregroundServiceType="mediaPlayback"
             android:icon="@mipmap/ic_launcher"
-            android:exported="true"
-            android:roundIcon="@mipmap/ic_launcher">
-            <!--
-            Workaround to get apps that search for media apps by checking for a BroadcastReceiver
-            to detect Auxio, as we let the media APIs handle this.
-            -->
-            <intent-filter>
-                <action android:name="android.intent.action.MEDIA_BUTTON" />
-            </intent-filter>
-        </service>
+            android:exported="false"
+            android:roundIcon="@mipmap/ic_launcher" />
 
         <receiver
             android:name=".widgets.WidgetProvider"

app/src/main/java/org/oxycblt/auxio/playback/system/AudioReactor.kt

@@ -144,6 +144,8 @@ class AudioReactor(
 
         // Final adjustment along the volume curve.
         // Ensure this is clamped to 0 or 1 so that it can be used as a volume.
+        // TODO: Support positive ReplayGain values. They're more obscure but still exist.
+        //  It will likely require moving functionality from this class to an AudioProcessor
         volume = MathUtils.clamp((10f.pow((adjust / 20f))), 0f, 1f)
     }
 
@@ -191,8 +193,10 @@ class AudioReactor(
         }
 
         // Case 2: R128 ReplayGain, most commonly found on FLAC files.
-        // While technically there is the R128 base gain in Opus files, ExoPlayer doesn't
-        // have metadata parsing functionality for those, so we just ignore it.
+        // While technically there is the R128 base gain in Opus files, that is automatically
+        // applied by the media framework [which ExoPlayer relies on]. The only reason we would
+        // want to read it is to zero previous ReplayGain values for being invalid, however there
+        // is no demand to fix that edge case right now.
         tags.findLast { tag -> tag.key == R128_TRACK }?.let { tag ->
             trackGain += tag.value / 256f
             found = true

app/src/main/java/org/oxycblt/auxio/playback/system/MediaButtonReceiver.kt

@@ -0,0 +1,27 @@
+package org.oxycblt.auxio.playback.system
+
+import android.content.BroadcastReceiver
+import android.content.ComponentName
+import android.content.Context
+import android.content.Intent
+import androidx.core.content.ContextCompat
+
+/**
+ * Some apps like to party like it's 2011 and just blindly query for the ACTION_MEDIA_BUTTON
+ * intent to determine the media apps on a system. *Auxio does not expose this.* Auxio exposes
+ * a MediaSession that an app should control instead through the much better MediaController API.
+ * But who cares about that, we need to make sure the 3% of barely functioning TouchWiz devices
+ * running KitKat don't break! To prevent Auxio from not showing up at all in these apps, we
+ * declare a BroadcastReceiver that deliberately handles this event. This also means that Auxio
+ * will start without warning if you use the media buttons while the app exists, because I guess
+ * we just have to deal with this.
+ * @author OxygenCobalt
+ */
+class MediaButtonReceiver : BroadcastReceiver() {
+    override fun onReceive(context: Context, intent: Intent) {
+        if (intent.action == Intent.ACTION_MEDIA_BUTTON) {
+            intent.component = ComponentName(context, PlaybackService::class.java)
+            ContextCompat.startForegroundService(context, intent)
+        }
+    }
+}

app/src/main/java/org/oxycblt/auxio/playback/system/PlaybackService.kt

@@ -20,7 +20,6 @@ package org.oxycblt.auxio.playback.system
 
 import android.app.NotificationManager
 import android.app.Service
-import android.bluetooth.BluetoothDevice
 import android.content.BroadcastReceiver
 import android.content.Context
 import android.content.Intent
@@ -88,7 +87,7 @@ class PlaybackService : Service(), Player.Listener, PlaybackStateManager.Callbac
     // System backend components
     private lateinit var audioReactor: AudioReactor
     private lateinit var widgets: WidgetController
-    private val systemReceiver = SystemEventReceiver()
+    private val systemReceiver = PlaybackReceiver()
 
     // Managers
     private val playbackManager = PlaybackStateManager.getInstance()
@@ -102,10 +101,13 @@ class PlaybackService : Service(), Player.Listener, PlaybackStateManager.Callbac
 
     // --- SERVICE OVERRIDES ---
 
-    override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
-        // Since this service exposes a media button intent, pass it off to the
-        // MediaSession if the intent really is an instance of one.
-        MediaButtonReceiver.handleIntent(mediaSession, intent)
+    override fun onStartCommand(intent: Intent, flags: Int, startId: Int): Int {
+        if (intent.action == Intent.ACTION_MEDIA_BUTTON) {
+            // Workaround to get GadgetBridge and other apps that blindly query for
+            // ACTION_MEDIA_BUTTON working.
+            MediaButtonReceiver.handleIntent(mediaSession, intent)
+        }
+
         return START_NOT_STICKY
     }
 
@@ -146,18 +148,16 @@ class PlaybackService : Service(), Player.Listener, PlaybackStateManager.Callbac
 
         // Then the notif/headset callbacks
         IntentFilter().apply {
+            addAction(AudioManager.ACTION_SCO_AUDIO_STATE_UPDATED)
+            addAction(AudioManager.ACTION_AUDIO_BECOMING_NOISY)
+            addAction(AudioManager.ACTION_HEADSET_PLUG)
+
             addAction(ACTION_LOOP)
             addAction(ACTION_SHUFFLE)
             addAction(ACTION_SKIP_PREV)
             addAction(ACTION_PLAY_PAUSE)
             addAction(ACTION_SKIP_NEXT)
             addAction(ACTION_EXIT)
-
-            addAction(BluetoothDevice.ACTION_ACL_CONNECTED)
-            addAction(BluetoothDevice.ACTION_ACL_DISCONNECTED)
-            addAction(AudioManager.ACTION_AUDIO_BECOMING_NOISY)
-            addAction(Intent.ACTION_HEADSET_PLUG)
-
             addAction(WidgetProvider.ACTION_WIDGET_UPDATE)
 
             registerReceiver(systemReceiver, this)
@@ -449,15 +449,29 @@ class PlaybackService : Service(), Player.Listener, PlaybackStateManager.Callbac
     }
 
     /**
-     * A [BroadcastReceiver] for receiving system events from notifications, widgets, or
-     * headset plug events.
+     * A [BroadcastReceiver] for receiving general playback events from the system.
      */
-    private inner class SystemEventReceiver : BroadcastReceiver() {
+    private inner class PlaybackReceiver : BroadcastReceiver() {
         override fun onReceive(context: Context, intent: Intent) {
             when (intent.action) {
+                // --- SYSTEM EVENTS ---
+                AudioManager.ACTION_SCO_AUDIO_STATE_UPDATED -> {
+                    when (intent.getIntExtra(AudioManager.EXTRA_SCO_AUDIO_STATE, -1)) {
+                        AudioManager.SCO_AUDIO_STATE_CONNECTED -> resumeFromPlug()
+                        AudioManager.SCO_AUDIO_STATE_DISCONNECTED -> pauseFromPlug()
+                    }
+                }
 
-                // --- NOTIFICATION CASES ---
+                AudioManager.ACTION_AUDIO_BECOMING_NOISY -> pauseFromPlug()
 
+                AudioManager.ACTION_HEADSET_PLUG -> {
+                    when (intent.getIntExtra("state", -1)) {
+                        0 -> resumeFromPlug()
+                        1 -> pauseFromPlug()
+                    }
+                }
+
+                // --- AUXIO EVENTS ---
                 ACTION_PLAY_PAUSE -> playbackManager.setPlaying(
                     !playbackManager.isPlaying
                 )
@@ -478,57 +492,41 @@ class PlaybackService : Service(), Player.Listener, PlaybackStateManager.Callbac
                     stopForegroundAndNotification()
                 }
 
-                // --- HEADSET CASES ---
-
-                BluetoothDevice.ACTION_ACL_CONNECTED -> resumeFromPlug()
-                BluetoothDevice.ACTION_ACL_DISCONNECTED -> pauseFromPlug()
-
-                AudioManager.ACTION_SCO_AUDIO_STATE_UPDATED -> {
-                    when (intent.getIntExtra(AudioManager.EXTRA_SCO_AUDIO_STATE, -1)) {
-                        AudioManager.SCO_AUDIO_STATE_CONNECTED -> resumeFromPlug()
-                        AudioManager.SCO_AUDIO_STATE_DISCONNECTED -> pauseFromPlug()
-                    }
-                }
-
-                AudioManager.ACTION_AUDIO_BECOMING_NOISY -> pauseFromPlug()
-
-                Intent.ACTION_HEADSET_PLUG -> {
-                    when (intent.getIntExtra("state", -1)) {
-                        CONNECTED -> resumeFromPlug()
-                        DISCONNECTED -> pauseFromPlug()
-                    }
-                }
-
                 WidgetProvider.ACTION_WIDGET_UPDATE -> widgets.update()
-            }
-        }
 
-        /**
-         * Resume from a headset plug event, as long as its allowed.
-         */
-        private fun resumeFromPlug() {
-            if (playbackManager.song != null && settingsManager.doPlugMgt) {
-                logD("Device connected, resuming...")
-
-                playbackManager.setPlaying(true)
-            }
-        }
-
-        /**
-         * Pause from a headset plug, as long as its allowed.
-         */
-        private fun pauseFromPlug() {
-            if (playbackManager.song != null && settingsManager.doPlugMgt) {
-                logD("Device disconnected, pausing...")
-
-                playbackManager.setPlaying(false)
+                else -> handleSystemIntent(intent)
             }
         }
     }
 
+    private fun handleSystemIntent(intent: Intent) {
+        when (intent.action) {
+
+            Intent.ACTION_MEDIA_BUTTON -> MediaButtonReceiver.handleIntent(mediaSession, intent)
+        }
+    }
+
+    /**
+     * Resume from a headset plug event, as long as its allowed.
+     */
+    private fun resumeFromPlug() {
+        if (playbackManager.song != null && settingsManager.doPlugMgt) {
+            logD("Device connected, resuming...")
+            playbackManager.setPlaying(true)
+        }
+    }
+
+    /**
+     * Pause from a headset plug, as long as its allowed.
+     */
+    private fun pauseFromPlug() {
+        if (playbackManager.song != null && settingsManager.doPlugMgt) {
+            logD("Device disconnected, pausing...")
+            playbackManager.setPlaying(false)
+        }
+    }
+
     companion object {
-        private const val DISCONNECTED = 0
-        private const val CONNECTED = 1
         private const val POS_POLL_INTERVAL = 500L
 
         const val ACTION_LOOP = BuildConfig.APPLICATION_ID + ".action.LOOP"

app/src/main/java/org/oxycblt/auxio/search/SearchViewModel.kt

@@ -71,7 +71,6 @@ class SearchViewModel : ViewModel() {
 
         if (query.isEmpty() || musicStore == null) {
             mSearchResults.value = listOf()
-
             return
         }
 
@@ -80,7 +79,7 @@ class SearchViewModel : ViewModel() {
             val sort = Sort.ByName(true)
             val results = mutableListOf<BaseModel>()
 
-            // A filter mode of null means to not filter at all.
+            // Note: a filter mode of null means to not filter at all.
 
             if (mFilterMode == null || mFilterMode == DisplayMode.SHOW_ARTISTS) {
                 musicStore.artists.filterByOrNull(query)?.let { artists ->

app/src/main/res/values-de/strings.xml

@@ -73,7 +73,7 @@
     <string name="set_focus_desc">Pausieren wenn andere Töne abspielt wird [Bsp. Anrufe]</string>
     <string name="set_plug_mgt">Kopfhörerfokus</string>
     <string name="set_plug_mgt_desc">Abspielen/Pausieren wenn sich die Kopfhörerverbindung ändert</string>
-    <string name="set_replay_gain">ReplayGain (Nur MP3/FLAC)</string>
+    <string name="set_replay_gain">ReplayGain (Experimentell)</string>
     <string name="set_replay_gain_off">Aus</string>
     <string name="set_replay_gain_track">Titel bevorzugen</string>
     <string name="set_replay_gain_album">Album bevorzugen</string>

app/src/main/res/values/strings.xml

@@ -85,7 +85,7 @@
     <string name="set_focus_desc">Pause when other audio plays (ex. Calls)</string>
     <string name="set_plug_mgt">Headset focus</string>
     <string name="set_plug_mgt_desc">Play/Pause when the headset connection changes</string>
-    <string name="set_replay_gain">ReplayGain</string>
+    <string name="set_replay_gain">ReplayGain (Experimental)</string>
     <string name="set_replay_gain_off">Off</string>
     <string name="set_replay_gain_track">Prefer track</string>
     <string name="set_replay_gain_album">Prefer album</string>

info/FAQ.md

@@ -37,10 +37,12 @@ This is for a couple reason:
 defined ReplayGain standard for those.
 - Auxio doesn't recognize your ReplayGain tags. This is usually because of a non-standard tag like ID3v2's `RVAD` or
 an unrecognized name.
+- Your tags use a ReplayGain value higher than 0. Due to technical limitations, Auxio does not support this right now. 
+I do plan to add it eventually.
 
 #### What is dynamic ReplayGain?
 
-Dynamic ReplayGain is a quirk based off the FooBar2000 plugin that dynamically switches from track gain to album
+Dynamic ReplayGain is a quirk setting based off the FooBar2000 plugin that dynamically switches from track gain to album
 gain depending on if the current playback is from an album or not.
 
 #### Why are accents lighter/less saturated in dark mode?

prebuild.py

@@ -30,7 +30,7 @@ def sh(cmd):
         print(FATAL + "fatal:" + NC + " command failed with exit code " + str(code))
         sys.exit(1)
         
-exoplayer_path = os.path.join(os.path.abspath(os.curdir), "deps", "exoplayer")
+exoplayer_path = os.path.join(os.path.abspath(os.curdir), "srclibs", "exoplayer")
 
 if os.path.exists(exoplayer_path):
     reinstall = input(INFO + "info:" + NC + " exoplayer is already installed. would you like to reinstall it? [y/n] ")
@@ -69,7 +69,7 @@ if ndk_path is None or not os.path.isfile(os.path.join(ndk_path, "ndk_build")):
         system.exit(1)
 
 # Now try to install ExoPlayer.
-sh("rm -rf deps")
+sh("rm -rf srclibs")
 
 print(INFO + "info:" + NC + " cloning exoplayer...")
 sh("git clone https://github.com/oxygencobalt/ExoPlayer.git " + exoplayer_path)

settings.gradle

@@ -1,4 +1,4 @@
 include ':app'
 rootProject.name = "Auxio"
 gradle.ext.exoplayerModulePrefix = 'exoplayer-'
-apply from: file("deps/exoplayer/core_settings.gradle")
+apply from: file("srclibs/exoplayer/core_settings.gradle")