Expose getAudioDevicesForAttributes

Allow all apps to query the audio device output(s) for an AudioTrack
with defined AudioAttributes.
Provide an alternative path (AudioService#getDevicesForAttributesUnprotected)
to query this similar with the existing gated SystemApi.

Test: atest android.media.audio.cts.AudioDevicesForAttributesTest
Bug: 190810951
Change-Id: Id8bfcf809f42bd5500d59b96a2595a1b8b0d855b

core/api/current.txt

@@ -20955,6 +20955,7 @@ package android.media {
     method @NonNull public java.util.List<android.media.AudioPlaybackConfiguration> getActivePlaybackConfigurations();
     method @NonNull public java.util.List<android.media.AudioRecordingConfiguration> getActiveRecordingConfigurations();
     method public int getAllowedCapturePolicy();
+    method @NonNull public java.util.List<android.media.AudioDeviceInfo> getAudioDevicesForAttributes(@NonNull android.media.AudioAttributes);
     method public int getAudioHwSyncForSession(int);
     method @NonNull public java.util.List<android.media.AudioDeviceInfo> getAvailableCommunicationDevices();
     method @Nullable public android.media.AudioDeviceInfo getCommunicationDevice();

media/java/android/media/AudioManager.java

@@ -79,6 +79,7 @@ import java.lang.annotation.RetentionPolicy;
 import java.lang.ref.WeakReference;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Iterator;
@@ -5665,6 +5666,43 @@ public class AudioManager {
         }
     }
 
+    /**
+     * Get the audio devices that would be used for the routing of the given audio attributes.
+     * These are the devices anticipated to play sound from an {@link AudioTrack} created with
+     * the specified {@link AudioAttributes}.
+     * The audio routing can change if audio devices are physically connected or disconnected or
+     * concurrently through {@link AudioRouting} or {@link MediaRouter}.
+     * @param attributes the {@link AudioAttributes} for which the routing is being queried
+     * @return an empty list if there was an issue with the request, a list of
+     * {@link AudioDeviceInfo} otherwise (typically one device, except for duplicated paths).
+     */
+    public @NonNull List<AudioDeviceInfo> getAudioDevicesForAttributes(
+            @NonNull AudioAttributes attributes) {
+        final List<AudioDeviceAttributes> devicesForAttributes;
+        try {
+            Objects.requireNonNull(attributes);
+            final IAudioService service = getService();
+            devicesForAttributes = service.getDevicesForAttributesUnprotected(attributes);
+        } catch (Exception e) {
+            Log.i(TAG, "No audio devices available for specified attributes.");
+            return Collections.emptyList();
+        }
+
+        // Map from AudioDeviceAttributes to AudioDeviceInfo
+        AudioDeviceInfo[] outputDeviceInfos = getDevicesStatic(GET_DEVICES_OUTPUTS);
+        List<AudioDeviceInfo> deviceInfosForAttributes = new ArrayList<>();
+        for (AudioDeviceAttributes deviceForAttributes : devicesForAttributes) {
+            for (AudioDeviceInfo deviceInfo : outputDeviceInfos) {
+                if (deviceForAttributes.getType() == deviceInfo.getType()
+                        && TextUtils.equals(deviceForAttributes.getAddress(),
+                                deviceInfo.getAddress())) {
+                    deviceInfosForAttributes.add(deviceInfo);
+                }
+            }
+        }
+        return Collections.unmodifiableList(deviceInfosForAttributes);
+    }
+
     /**
      * @hide
      * Volume behavior for an audio device that has no particular volume behavior set. Invalid as

media/java/android/media/IAudioService.aidl

@@ -308,6 +308,8 @@ interface IAudioService {
 
     List<AudioDeviceAttributes> getDevicesForAttributes(in AudioAttributes attributes);
 
+    List<AudioDeviceAttributes> getDevicesForAttributesUnprotected(in AudioAttributes attributes);
+
     int setAllowedCapturePolicy(in int capturePolicy);
 
     int getAllowedCapturePolicy();

services/core/java/com/android/server/audio/AudioService.java

@@ -2611,6 +2611,16 @@ public class AudioService extends IAudioService.Stub
         return getDevicesForAttributesInt(attributes);
     }
 
+    /** @see AudioManager#getAudioDevicesForAttributes(AudioAttributes)
+     * This method is similar with AudioService#getDevicesForAttributes,
+     * only it doesn't enforce permissions because it is used by an unprivileged public API
+     * instead of the system API.
+     */
+    public @NonNull ArrayList<AudioDeviceAttributes> getDevicesForAttributesUnprotected(
+            @NonNull AudioAttributes attributes) {
+        return getDevicesForAttributesInt(attributes);
+    }
+
     /**
      * @see AudioManager#isMusicActive()
      * @param remotely true if query is for remote playback (cast), false for local playback.