audiosystem: Add API for listening to effect session events

 * This API will allow attaching a global listener which will
   notify the application when audio effect sessions are
   attached or removed on a stream. This requires that the policy is
   configured to automatically attach a set of effects.

Change-Id: Iaf1ca133765045322b005d4148e2c4e86a9c3913

1 files changed, 50 insertions, 0 deletions

diff --git a/media/java/android/media/AudioSystem.java b/media/java/android/media/AudioSystem.java
index 927cd87..8bf1604 100644
--- a/media/java/android/media/AudioSystem.java
+++ b/media/java/android/media/AudioSystem.java
@@ -268,6 +268,54 @@ public class AudioSystem
     }
 
 
+   /**
+     * Handles events for the audio policy manager about effect sessions
+     * @see android.media.audiopolicy.AudioPolicy
+     */
+    public interface EffectSessionCallback
+    {
+        void onSessionAdded(int stream, int sessionId);
+
+        void onSessionRemoved(int stream, int sessionId);
+    }
+
+    //keep in sync with include/media/AudioPolicy.h
+    private final static int AUDIO_OUTPUT_SESSION_EFFECTS_UPDATE = 10;
+
+    private static EffectSessionCallback sEffectSessionCallback;
+
+    public static void setEffectSessionCallback(EffectSessionCallback cb)
+    {
+        synchronized (AudioSystem.class) {
+            sEffectSessionCallback = cb;
+            native_register_effect_session_callback();
+        }
+    }
+
+    private static void effectSessionCallbackFromNative(int event, int stream, int sessionId, boolean added)
+    {
+        EffectSessionCallback cb = null;
+        synchronized (AudioSystem.class) {
+            if (sEffectSessionCallback != null) {
+                cb = sEffectSessionCallback;
+            }
+        }
+        if (cb != null) {
+            switch(event) {
+                case AUDIO_OUTPUT_SESSION_EFFECTS_UPDATE:
+                    if (added) {
+                        cb.onSessionAdded(stream, sessionId);
+                    } else {
+                        cb.onSessionRemoved(stream, sessionId);
+                    }
+                    break;
+                default:
+                    Log.e(TAG, "effectSessionCallbackFromNative: unknown event " + event);
+            }
+        }
+    }
+
+
     /*
      * Error codes used by public APIs (AudioTrack, AudioRecord, AudioManager ...)
      * Must be kept in sync with frameworks/base/core/jni/android_media_AudioErrors.h
@@ -648,6 +696,8 @@ public class AudioSystem
     // declare this instance as having a dynamic policy callback handler
     private static native final void native_register_dynamic_policy_callback();
 
+    private static native final void native_register_effect_session_callback();
+
     // must be kept in sync with value in include/system/audio.h
     public static final int AUDIO_HW_SYNC_INVALID = 0;