From a4d5841eb188a639d43b70134dcaf600416111b5 Mon Sep 17 00:00:00 2001
From: Jasmine Cha <chajasmine@google.com>
Date: Fri, 20 Aug 2021 11:59:04 +0800
Subject: [PATCH] RotationHelper: send active displayId to audio HAL

Send active displayId to audio HAL can improve sound quality in
different postures for foldable devices.

Bug: 197196724
Test: check parameters when folded/unfolded device
Change-Id: I255122c93ccc93257848af61336026305b5a0d25
---
 .../android/server/audio/RotationHelper.java  | 23 ++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/services/core/java/com/android/server/audio/RotationHelper.java b/services/core/java/com/android/server/audio/RotationHelper.java
index ad7216600e616..872b1feb2d727 100644
--- a/services/core/java/com/android/server/audio/RotationHelper.java
+++ b/services/core/java/com/android/server/audio/RotationHelper.java
@@ -21,20 +21,26 @@ import android.hardware.display.DisplayManager;
 import android.media.AudioSystem;
 import android.os.Handler;
 import android.util.Log;
+import android.view.Display;
 import android.view.Surface;
 import android.view.WindowManager;
 
 /**
  * Class to handle device rotation events for AudioService, and forward device rotation
- * to the audio HALs through AudioSystem.
+ * and current active ID to the audio HALs through AudioSystem.
  *
  * The role of this class is to monitor device orientation changes, and upon rotation,
  * verify the UI orientation. In case of a change, send the new orientation, in increments
  * of 90deg, through AudioSystem.
  *
+ * Another role of this class is to track current active display ID changes. In case of a
+ * change, send the new active display ID through AudioSystem.
+ *
  * Note that even though we're responding to device orientation events, we always
  * query the display rotation so audio stays in sync with video/dialogs. This is
  * done with .getDefaultDisplay().getRotation() from WINDOW_SERVICE.
+ *
+ * We also monitor current display ID and audio is able to know which display is active.
  */
 class RotationHelper {
 
@@ -43,7 +49,9 @@ class RotationHelper {
     private static AudioDisplayListener sDisplayListener;
 
     private static final Object sRotationLock = new Object();
+    private static final Object sActiveDisplayLock = new Object();
     private static int sDeviceRotation = Surface.ROTATION_0; // R/W synchronized on sRotationLock
+    private static int sDisplayId = Display.DEFAULT_DISPLAY; // synchronized on sActiveDisplayLock
 
     private static Context sContext;
     private static Handler sHandler;
@@ -111,6 +119,18 @@ class RotationHelper {
         }
     }
 
+    /**
+     * Query current display active id and publish the change if any.
+     */
+    static void updateActiveDisplayId(int displayId) {
+        synchronized (sActiveDisplayLock) {
+            if (displayId != Display.DEFAULT_DISPLAY && sDisplayId != displayId) {
+                sDisplayId = displayId;
+                AudioSystem.setParameters("active_displayId=" + sDisplayId);
+            }
+        }
+    }
+
     /**
      * Uses android.hardware.display.DisplayManager.DisplayListener
      */
@@ -126,6 +146,7 @@ class RotationHelper {
 
         @Override
         public void onDisplayChanged(int displayId) {
+            updateActiveDisplayId(displayId);
             updateOrientation();
         }
     }