voice reply improcement

gearslip/src/main/java/app/seb3thehacker/gearslip/car/CarAssistant.kt

@@ -15,6 +15,7 @@ import androidx.core.content.ContextCompat
 import app.seb3thehacker.gearslip.call.CallUiState
 import app.seb3thehacker.gearslip.call.CarCalls
 import app.seb3thehacker.gearslip.speech.SpeechEngine
+import app.seb3thehacker.gearslip.speech.VoiceFocus
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
 
@@ -119,15 +120,19 @@ object CarAssistant {
             _state.value = _state.value.copy(phase = Phase.IDLE)
             return
         }
+        appContext?.let(VoiceFocus::acquire)
         engine.setOnUtteranceProgressListener(object : UtteranceProgressListener() {
             override fun onStart(utteranceId: String?) {}
             override fun onDone(utteranceId: String?) {
+                VoiceFocus.release()
                 _state.value = _state.value.copy(phase = Phase.IDLE)
             }
             @Deprecated("Deprecated in Java, no replacement on this API level")
             override fun onError(utteranceId: String?) {
+                VoiceFocus.release()
                 _state.value = _state.value.copy(phase = Phase.IDLE)
             }
+            override fun onStop(utteranceId: String?, interrupted: Boolean) { VoiceFocus.release() }
         })
         engine.speak(text, TextToSpeech.QUEUE_FLUSH, null, "gearslip-assistant")
     }
@@ -138,17 +143,19 @@ object CarAssistant {
      */
     fun say(text: String, onDone: () -> Unit) {
         val engine = tts
-        if (engine == null || !ttsReady || text.isBlank()) {
+        val context = appContext
+        if (engine == null || context == null || !ttsReady || text.isBlank()) {
             mainHandler.post(onDone)
             return
         }
+        VoiceFocus.acquire(context)
         engine.setOnUtteranceProgressListener(object : UtteranceProgressListener() {
             override fun onStart(utteranceId: String?) {}
-            override fun onDone(utteranceId: String?) { mainHandler.post(onDone) }
+            override fun onDone(utteranceId: String?) { VoiceFocus.release(); mainHandler.post(onDone) }
             @Deprecated("Deprecated in Java, no replacement on this API level")
-            override fun onError(utteranceId: String?) { mainHandler.post(onDone) }
+            override fun onError(utteranceId: String?) { VoiceFocus.release(); mainHandler.post(onDone) }
             // Stopped part way: whoever stopped it has already moved on.
-            override fun onStop(utteranceId: String?, interrupted: Boolean) {}
+            override fun onStop(utteranceId: String?, interrupted: Boolean) { VoiceFocus.release() }
         })
         engine.speak(text, TextToSpeech.QUEUE_FLUSH, null, "gearslip-say")
     }

gearslip/src/main/java/app/seb3thehacker/gearslip/speech/SpeechEngine.kt

@@ -85,13 +85,16 @@ object SpeechEngine {
         worker.execute {
             if (id != run) return@execute
             if (!ensureLoaded(app)) return@execute post { onError(NOT_LOADED) }
-            if (cue) cue()
-            if (id != run) return@execute
+            VoiceFocus.acquire(app)
             val audio = try {
+                if (cue) cue()
+                if (id != run) return@execute
                 record(id) { post(onSpeaking) }
             } catch (t: Throwable) {
                 GearslipLog.e("speech: recording failed", t)
                 return@execute post { onError("The microphone isn't available right now.") }
+            } finally {
+                VoiceFocus.release()
             }
             if (id != run) return@execute
             if (audio == null) return@execute post { onError("Didn't catch that.") }

gearslip/src/main/java/app/seb3thehacker/gearslip/speech/VoiceFocus.kt

@@ -0,0 +1,69 @@
+package app.seb3thehacker.gearslip.speech
+
+import android.content.Context
+import android.media.AudioAttributes
+import android.media.AudioFocusRequest
+import android.media.AudioManager
+import android.os.Handler
+import android.os.Looper
+import app.seb3thehacker.gearslip.GearslipLog
+
+/**
+ * Pauses the music while Gearslip talks or listens. Without it the microphone heard the song and
+ * Whisper wrote down lyrics, and a message read aloud had to compete with the music.
+ *
+ * Transient exclusive focus makes music apps pause rather than duck, and they resume on their
+ * own once it's given back. The release waits a moment, so a read-aloud message followed by
+ * "Do you want to reply?" and the microphone is one pause, not three.
+ */
+object VoiceFocus {
+
+    private const val RELEASE_DELAY_MS = 1_500L
+
+    private val main = Handler(Looper.getMainLooper())
+    private var request: AudioFocusRequest? = null
+    private var audio: AudioManager? = null
+    private var holders = 0
+
+    private val releaseNow = Runnable {
+        val r = request ?: return@Runnable
+        audio?.abandonAudioFocusRequest(r)
+        request = null
+        GearslipLog.i("voice: gave audio focus back")
+    }
+
+    /** Pauses the music until a matching [release]. Safe from any thread. */
+    fun acquire(context: Context) {
+        val app = context.applicationContext
+        main.post {
+            holders++
+            main.removeCallbacks(releaseNow)
+            if (request != null) return@post
+            val manager = app.getSystemService(AudioManager::class.java) ?: return@post
+            val r = AudioFocusRequest.Builder(AudioManager.AUDIOFOCUS_GAIN_TRANSIENT_EXCLUSIVE)
+                .setAudioAttributes(
+                    AudioAttributes.Builder()
+                        .setUsage(AudioAttributes.USAGE_ASSISTANT)
+                        .setContentType(AudioAttributes.CONTENT_TYPE_SPEECH)
+                        .build(),
+                )
+                .setOnAudioFocusChangeListener { }
+                .build()
+            val granted = manager.requestAudioFocus(r) == AudioManager.AUDIOFOCUS_REQUEST_GRANTED
+            GearslipLog.i("voice: audio focus ${if (granted) "granted, music paused" else "refused"}")
+            if (granted) {
+                audio = manager
+                request = r
+            }
+        }
+    }
+
+    /** Lets the music come back shortly, unless something else takes focus again first. */
+    fun release() {
+        main.post {
+            if (holders == 0) return@post
+            holders--
+            if (holders == 0) main.postDelayed(releaseNow, RELEASE_DELAY_MS)
+        }
+    }
+}