Gain temporary audio focus during voice memo recording.

app/src/main/java/org/thoughtcrime/securesms/audio/AudioRecorder.java

@@ -1,6 +1,7 @@
 package org.thoughtcrime.securesms.audio;
 
 import android.content.Context;
+import android.media.AudioManager;
 import android.net.Uri;
 import android.os.Build;
 import android.os.ParcelFileDescriptor;
@@ -25,13 +26,15 @@ public class AudioRecorder {
 
   private static final ExecutorService executor = SignalExecutors.newCachedSingleThreadExecutor("signal-AudioRecorder");
 
-  private final Context context;
+  private final Context                   context;
+  private final AudioRecorderFocusManager audioFocusManager;
 
   private Recorder recorder;
   private Uri      captureUri;
 
   public AudioRecorder(@NonNull Context context) {
     this.context = context;
+    audioFocusManager = AudioRecorderFocusManager.create(context, focusChange -> stopRecording());
   }
 
   public void startRecording() {
@@ -52,6 +55,10 @@ public class AudioRecorder {
                                  .createForDraftAttachmentAsync(context, () -> Log.i(TAG, "Write successful."), e -> Log.w(TAG, "Error during recording", e));
 
         recorder = Build.VERSION.SDK_INT >= 26 ? new MediaRecorderWrapper() : new AudioCodec();
+        int focusResult = audioFocusManager.requestAudioFocus();
+        if (focusResult != AudioManager.AUDIOFOCUS_REQUEST_GRANTED) {
+          Log.w(TAG, "Could not gain audio focus. Received result code " + focusResult);
+        }
         recorder.start(fds[1]);
       } catch (IOException e) {
         Log.w(TAG, e);
@@ -70,6 +77,7 @@ public class AudioRecorder {
         return;
       }
 
+      audioFocusManager.abandonAudioFocus();
       recorder.stop();
 
       try {

app/src/main/java/org/thoughtcrime/securesms/audio/AudioRecorderFocusManager.kt

@@ -0,0 +1,62 @@
+package org.thoughtcrime.securesms.audio
+
+import android.content.Context
+import android.media.AudioAttributes
+import android.media.AudioFocusRequest
+import android.media.AudioManager
+import android.media.AudioManager.OnAudioFocusChangeListener
+import android.os.Build
+import androidx.annotation.RequiresApi
+import org.thoughtcrime.securesms.util.ServiceUtil
+
+abstract class AudioRecorderFocusManager(val context: Context) {
+  protected val audioManager: AudioManager = ServiceUtil.getAudioManager(context)
+
+  abstract fun requestAudioFocus(): Int
+  abstract fun abandonAudioFocus(): Int
+
+  companion object {
+    @JvmStatic
+    fun create(context: Context, changeListener: OnAudioFocusChangeListener): AudioRecorderFocusManager {
+      return if (Build.VERSION.SDK_INT >= 26) {
+        AudioRecorderFocusManager26(context, changeListener)
+      } else {
+        AudioRecorderFocusManagerLegacy(context, changeListener)
+      }
+    }
+  }
+}
+
+@RequiresApi(26)
+private class AudioRecorderFocusManager26(context: Context, changeListener: OnAudioFocusChangeListener) : AudioRecorderFocusManager(context) {
+  val audioFocusRequest: AudioFocusRequest
+
+  init {
+    val audioAttributes = AudioAttributes.Builder()
+      .setUsage(AudioAttributes.USAGE_MEDIA)
+      .setContentType(AudioAttributes.CONTENT_TYPE_MUSIC)
+      .build()
+    audioFocusRequest = AudioFocusRequest.Builder(AudioManager.AUDIOFOCUS_GAIN_TRANSIENT_EXCLUSIVE)
+      .setAudioAttributes(audioAttributes)
+      .setOnAudioFocusChangeListener(changeListener)
+      .build()
+  }
+
+  override fun requestAudioFocus(): Int {
+    return audioManager.requestAudioFocus(audioFocusRequest)
+  }
+
+  override fun abandonAudioFocus(): Int {
+    return audioManager.abandonAudioFocusRequest(audioFocusRequest)
+  }
+}
+
+private class AudioRecorderFocusManagerLegacy(context: Context, val changeListener: OnAudioFocusChangeListener) : AudioRecorderFocusManager(context) {
+  override fun requestAudioFocus(): Int {
+    return audioManager.requestAudioFocus(changeListener, AudioManager.STREAM_MUSIC, AudioManager.AUDIOFOCUS_GAIN_TRANSIENT_EXCLUSIVE)
+  }
+
+  override fun abandonAudioFocus(): Int {
+    return audioManager.abandonAudioFocus(changeListener)
+  }
+}