From 0c285639a7c8f45bb91eb0cc9f5bb3fe712eb6f6 Mon Sep 17 00:00:00 2001
From: Brian Duddie <bduddie@google.com>
Date: Mon, 14 Feb 2022 10:41:29 -0800
Subject: [PATCH] Clarify optionality of velocity in head tracker sensor

Bug: 218911221
Test: n/a, comment update only
Change-Id: I893397c9446e5c976e3dc9e68d65d67e7128ba9e
---
 core/java/android/hardware/SensorEvent.java | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/core/java/android/hardware/SensorEvent.java b/core/java/android/hardware/SensorEvent.java
index 45d4c09921a64..f68fb9d5db566 100644
--- a/core/java/android/hardware/SensorEvent.java
+++ b/core/java/android/hardware/SensorEvent.java
@@ -664,16 +664,20 @@ public class SensorEvent {
      * The first three elements provide the transform from the (arbitrary, possibly slowly drifting)
      * reference frame to the head frame. The magnitude of this vector is in range [0, &pi;]
      * radians, while the value of individual axes is in range [-&pi;, &pi;]. The next three
-     * elements provide the estimated rotational velocity of the user's head relative to itself, in
-     * radians per second.
+     * elements optionally provide the estimated rotational velocity of the user's head relative to
+     * itself, in radians per second. If a given sensor does not support determining velocity, these
+     * elements are set to 0.
      *
      * <ul>
      *  <li> values[0] : X component of Euler vector representing rotation</li>
      *  <li> values[1] : Y component of Euler vector representing rotation</li>
      *  <li> values[2] : Z component of Euler vector representing rotation</li>
-     *  <li> values[3] : X component of Euler vector representing angular velocity</li>
-     *  <li> values[4] : Y component of Euler vector representing angular velocity</li>
-     *  <li> values[5] : Z component of Euler vector representing angular velocity</li>
+     *  <li> values[3] : X component of Euler vector representing angular velocity (if
+     *  supported, otherwise 0)</li>
+     *  <li> values[4] : Y component of Euler vector representing angular velocity (if
+     *  supported, otherwise 0)</li>
+     *  <li> values[5] : Z component of Euler vector representing angular velocity (if
+     *  supported, otherwise 0)</li>
      * </ul>
      *
      * <h4>{@link android.hardware.Sensor#TYPE_ACCELEROMETER_LIMITED_AXES