From 5f459046caf8b8ae25be83ce695eaea1bc7e73ef Mon Sep 17 00:00:00 2001
From: Eva Chen <evaschen@google.com>
Date: Mon, 10 Jan 2022 20:13:28 -0800
Subject: [PATCH] Add TYPE_HEADING sensor type to sensor framework.

Bug: 189983308
Test: Compiled
Change-Id: I183f176352fd6e08025647638cee35fd1600f3f0
---
 core/api/current.txt                        |  2 ++
 core/java/android/hardware/Sensor.java      | 19 +++++++++++++++++++
 core/java/android/hardware/SensorEvent.java | 18 ++++++++++++++++++
 3 files changed, 39 insertions(+)

diff --git a/core/api/current.txt b/core/api/current.txt
index f30a6eb4fa821..37754e70ea8f9 100644
--- a/core/api/current.txt
+++ b/core/api/current.txt
@@ -16886,6 +16886,7 @@ package android.hardware {
     field public static final String STRING_TYPE_GYROSCOPE_LIMITED_AXES = "android.sensor.gyroscope_limited_axes";
     field public static final String STRING_TYPE_GYROSCOPE_LIMITED_AXES_UNCALIBRATED = "android.sensor.gyroscope_limited_axes_uncalibrated";
     field public static final String STRING_TYPE_GYROSCOPE_UNCALIBRATED = "android.sensor.gyroscope_uncalibrated";
+    field public static final String STRING_TYPE_HEADING = "android.sensor.heading";
     field public static final String STRING_TYPE_HEAD_TRACKER = "android.sensor.head_tracker";
     field public static final String STRING_TYPE_HEART_BEAT = "android.sensor.heart_beat";
     field public static final String STRING_TYPE_HEART_RATE = "android.sensor.heart_rate";
@@ -16921,6 +16922,7 @@ package android.hardware {
     field public static final int TYPE_GYROSCOPE_LIMITED_AXES = 39; // 0x27
     field public static final int TYPE_GYROSCOPE_LIMITED_AXES_UNCALIBRATED = 41; // 0x29
     field public static final int TYPE_GYROSCOPE_UNCALIBRATED = 16; // 0x10
+    field public static final int TYPE_HEADING = 42; // 0x2a
     field public static final int TYPE_HEAD_TRACKER = 37; // 0x25
     field public static final int TYPE_HEART_BEAT = 31; // 0x1f
     field public static final int TYPE_HEART_RATE = 21; // 0x15
diff --git a/core/java/android/hardware/Sensor.java b/core/java/android/hardware/Sensor.java
index 166ae451fb6dd..0d3aaf5757296 100644
--- a/core/java/android/hardware/Sensor.java
+++ b/core/java/android/hardware/Sensor.java
@@ -793,6 +793,21 @@ public final class Sensor {
     public static final String STRING_TYPE_GYROSCOPE_LIMITED_AXES_UNCALIBRATED =
             "android.sensor.gyroscope_limited_axes_uncalibrated";
 
+    /**
+     * A constant string describing a heading sensor.
+     *
+     * See {@link android.hardware.SensorEvent#values SensorEvent.values} for more details.
+     */
+    public static final int TYPE_HEADING = 42;
+
+    /**
+     * A constant string describing a heading sensor.
+     *
+     * @see #TYPE_HEADING
+     *
+     */
+    public static final String STRING_TYPE_HEADING = "android.sensor.heading";
+
     /**
      * A constant describing all sensor types.
      */
@@ -918,6 +933,7 @@ public final class Sensor {
             6, // SENSOR_TYPE_GYROSCOPE_LIMITED_AXES
             9, // SENSOR_TYPE_ACCELEROMETER_LIMITED_AXES_UNCALIBRATED
             9, // SENSOR_TYPE_GYROSCOPE_LIMITED_AXES_UNCALIBRATED
+            2, // SENSOR_TYPE_HEADING
     };
 
     /**
@@ -1385,6 +1401,9 @@ public final class Sensor {
             case TYPE_GYROSCOPE_LIMITED_AXES_UNCALIBRATED:
                 mStringType = STRING_TYPE_GYROSCOPE_LIMITED_AXES_UNCALIBRATED;
                 return true;
+            case TYPE_HEADING:
+                mStringType = STRING_TYPE_HEADING;
+                return true;
             default:
                 return false;
         }
diff --git a/core/java/android/hardware/SensorEvent.java b/core/java/android/hardware/SensorEvent.java
index 7da136f73c533..45d4c09921a64 100644
--- a/core/java/android/hardware/SensorEvent.java
+++ b/core/java/android/hardware/SensorEvent.java
@@ -779,6 +779,24 @@ public class SensorEvent {
      * </ul>
      * </p>
      *
+     * <h4>{@link android.hardware.Sensor#TYPE_HEADING Sensor.TYPE_HEADING}:</h4>
+     *
+     * A sensor of this type measures the direction in which the device is
+     * pointing relative to true north in degrees. The value must be between
+     * 0.0 (inclusive) and 360.0 (exclusive), with 0 indicating north, 90 east,
+     * 180 south, and 270 west.
+     *
+     * Accuracy is defined at 68% confidence. In the case where the underlying
+     * distribution is assumed Gaussian normal, this would be considered one
+     * standard deviation. For example, if heading returns 60 degrees, and
+     * accuracy returns 10 degrees, then there is a 68 percent probability of
+     * the true heading being between 50 degrees and 70 degrees.
+     *
+     * <ul>
+     *  <li> values[0]: Measured heading in degrees.</li>
+     *  <li> values[1]: Heading accuracy in degrees.</li>
+     * </ul>
+     *
      * @see GeomagneticField
      */
     public final float[] values;