Log when MotionPauseDetector detects onMotionPauseChanged

Test: verified logging locally
Bug: 232548865
Change-Id: I587481a380148127f715c5b1b59436b2cbc1533e
diff --git a/quickstep/src/com/android/quickstep/util/MotionPauseDetector.java b/quickstep/src/com/android/quickstep/util/MotionPauseDetector.java
index b83e26e..a3f7ae0 100644
--- a/quickstep/src/com/android/quickstep/util/MotionPauseDetector.java
+++ b/quickstep/src/com/android/quickstep/util/MotionPauseDetector.java
@@ -17,6 +17,7 @@
 
 import android.content.Context;
 import android.content.res.Resources;
+import android.util.Log;
 import android.view.MotionEvent;
 import android.view.VelocityTracker;
 
@@ -31,6 +32,8 @@
  */
 public class MotionPauseDetector {
 
+    private static final String TAG = "MotionPauseDetector";
+
     // The percentage of the previous speed that determines whether this is a rapid deceleration.
     // The bigger this number, the easier it is to trigger the first pause.
     private static final float RAPID_DECELERATION_FACTOR = 0.6f;
@@ -85,7 +88,8 @@
         mSpeedSomewhatFast = res.getDimension(R.dimen.motion_pause_detector_speed_somewhat_fast);
         mSpeedFast = res.getDimension(R.dimen.motion_pause_detector_speed_fast);
         mForcePauseTimeout = new Alarm();
-        mForcePauseTimeout.setOnAlarmListener(alarm -> updatePaused(true /* isPaused */));
+        mForcePauseTimeout.setOnAlarmListener(alarm -> updatePaused(true /* isPaused */,
+                "Force pause timeout after " +  alarm.getLastSetTimeout() + "ms" /* reason */));
         mMakePauseHarderToTrigger = makePauseHarderToTrigger;
         mVelocityProvider = new SystemVelocityProvider(axis);
     }
@@ -102,7 +106,7 @@
      */
     public void setDisallowPause(boolean disallowPause) {
         mDisallowPause = disallowPause;
-        updatePaused(mIsPaused);
+        updatePaused(mIsPaused, "Set disallowPause=" + disallowPause);
     }
 
     /**
@@ -134,21 +138,27 @@
         float speed = Math.abs(velocity);
         float previousSpeed = Math.abs(prevVelocity);
         boolean isPaused;
+        String isPausedReason = "";
         if (mIsPaused) {
             // Continue to be paused until moving at a fast speed.
             isPaused = speed < mSpeedFast || previousSpeed < mSpeedFast;
+            isPausedReason = "Was paused, but started moving at a fast speed";
         } else {
             if (velocity < 0 != prevVelocity < 0) {
                 // We're just changing directions, not necessarily stopping.
                 isPaused = false;
+                isPausedReason = "Velocity changed directions";
             } else {
                 isPaused = speed < mSpeedVerySlow && previousSpeed < mSpeedVerySlow;
+                isPausedReason = "Pause requires back to back slow speeds";
                 if (!isPaused && !mHasEverBeenPaused) {
                     // We want to be more aggressive about detecting the first pause to ensure it
                     // feels as responsive as possible; getting two very slow speeds back to back
                     // takes too long, so also check for a rapid deceleration.
                     boolean isRapidDeceleration = speed < previousSpeed * RAPID_DECELERATION_FACTOR;
                     isPaused = isRapidDeceleration && speed < mSpeedSomewhatFast;
+                    isPausedReason = "Didn't have back to back slow speeds, checking for rapid"
+                            + " deceleration on first pause only";
                 }
                 if (mMakePauseHarderToTrigger) {
                     if (speed < mSpeedSlow) {
@@ -156,22 +166,27 @@
                             mSlowStartTime = time;
                         }
                         isPaused = time - mSlowStartTime >= HARDER_TRIGGER_TIMEOUT;
+                        isPausedReason = "Maintained slow speed for sufficient duration when making"
+                                + " pause harder to trigger";
                     } else {
                         mSlowStartTime = 0;
                         isPaused = false;
+                        isPausedReason = "Intentionally making pause harder to trigger";
                     }
                 }
             }
         }
-        updatePaused(isPaused);
+        updatePaused(isPaused, isPausedReason);
     }
 
-    private void updatePaused(boolean isPaused) {
+    private void updatePaused(boolean isPaused, String reason) {
         if (mDisallowPause) {
+            reason = "Disallow pause; otherwise, would have been " + isPaused + " due to " + reason;
             isPaused = false;
         }
         if (mIsPaused != isPaused) {
             mIsPaused = isPaused;
+            Log.d(TAG, "onMotionPauseChanged, paused=" + mIsPaused + " reason=" + reason);
             boolean isFirstDetectedPause = !mHasEverBeenPaused && mIsPaused;
             if (mIsPaused) {
                 AccessibilityManagerCompat.sendPauseDetectedEventToTest(mContext);
diff --git a/src/com/android/launcher3/Alarm.java b/src/com/android/launcher3/Alarm.java
index d5b434c..e4aebf6 100644
--- a/src/com/android/launcher3/Alarm.java
+++ b/src/com/android/launcher3/Alarm.java
@@ -30,6 +30,7 @@
     private Handler mHandler;
     private OnAlarmListener mAlarmListener;
     private boolean mAlarmPending = false;
+    private long mLastSetTimeout;
 
     public Alarm() {
         mHandler = new Handler();
@@ -46,6 +47,7 @@
         mAlarmPending = true;
         long oldTriggerTime = mAlarmTriggerTime;
         mAlarmTriggerTime = currentTime + millisecondsInFuture;
+        mLastSetTimeout = millisecondsInFuture;
 
         // If the previous alarm was set for a longer duration, cancel it.
         if (mWaitingForCallback && oldTriggerTime > mAlarmTriggerTime) {
@@ -84,4 +86,9 @@
     public boolean alarmPending() {
         return mAlarmPending;
     }
+
+    /** Returns the last value passed to {@link #setAlarm(long)} */
+    public long getLastSetTimeout() {
+        return mLastSetTimeout;
+    }
 }