Ignore the closing MotionEvent of swipe gestures for falsing

The ZigZagClassifier falsly reports some swipes as false touches. The reason for that is in our touch event stream. The closing ACTION_UP event of a swipe might be a bit offseted from the previous ACTION_MOVE event and sometimes it is just enough to  push us over the allowed tolerance.

In this fix we drop the gesture closing ACTION_UP event if it is close in time to a previous ACTION_MOVE event.

Fixes: 236197248
Test: atest swipe notifications on the LS and observe the FalsingManager logs
Test: atest SystemUI:com.android.systemui.classifier

Change-Id: I33093ff77fd23a2913bd3adfd79a15e3ae66b316

5 files changed, 80 insertions, 10 deletions

diff --git a/packages/SystemUI/src/com/android/systemui/classifier/FalsingDataProvider.java b/packages/SystemUI/src/com/android/systemui/classifier/FalsingDataProvider.java
index bc0f9950f865..f83885b7bb32 100644
--- a/packages/SystemUI/src/com/android/systemui/classifier/FalsingDataProvider.java
+++ b/packages/SystemUI/src/com/android/systemui/classifier/FalsingDataProvider.java
@@ -38,6 +38,7 @@ import javax.inject.Inject;
 public class FalsingDataProvider {
 
     private static final long MOTION_EVENT_AGE_MS = 1000;
+    private static final long DROP_EVENT_THRESHOLD_MS = 50;
     private static final float THREE_HUNDRED_SIXTY_DEG = (float) (2 * Math.PI);
 
     private final int mWidthPixels;
@@ -60,6 +61,7 @@ public class FalsingDataProvider {
     private float mAngle = 0;
     private MotionEvent mFirstRecentMotionEvent;
     private MotionEvent mLastMotionEvent;
+    private boolean mDropLastEvent;
     private boolean mJustUnlockedWithFace;
     private boolean mA11YAction;
 
@@ -95,6 +97,12 @@ public class FalsingDataProvider {
             // Ensure prior gesture was completed. May be a no-op.
             completePriorGesture();
         }
+
+        // Drop the gesture closing event if it is close in time to a previous ACTION_MOVE event.
+        // The reason is that the closing ACTION_UP event of  a swipe can be a bit offseted from the
+        // previous ACTION_MOVE event and when it happens, it makes some classifiers fail.
+        mDropLastEvent = shouldDropEvent(motionEvent);
+
         mRecentMotionEvents.addAll(motionEvents);
 
         FalsingClassifier.logVerbose("Size: " + mRecentMotionEvents.size());
@@ -129,6 +137,7 @@ public class FalsingDataProvider {
             mPriorMotionEvents = mRecentMotionEvents;
             mRecentMotionEvents = new TimeLimitedMotionEventBuffer(MOTION_EVENT_AGE_MS);
         }
+        mDropLastEvent = false;
         mA11YAction = false;
     }
 
@@ -150,8 +159,18 @@ public class FalsingDataProvider {
         return mYdpi;
     }
 
+    /**
+     * Get the {@link MotionEvent}s of the most recent gesture.
+     *
+     * Note that this list may not include the last recorded event.
+     * @see #mDropLastEvent
+     */
     public List<MotionEvent> getRecentMotionEvents() {
-        return mRecentMotionEvents;
+        if (!mDropLastEvent || mRecentMotionEvents.isEmpty()) {
+            return mRecentMotionEvents;
+        } else {
+            return mRecentMotionEvents.subList(0, mRecentMotionEvents.size() - 1);
+        }
     }
 
     public List<MotionEvent> getPriorMotionEvents() {
@@ -169,7 +188,12 @@ public class FalsingDataProvider {
         return mFirstRecentMotionEvent;
     }
 
-    /** Get the last recorded {@link MotionEvent}. */
+    /**
+     * Get the last {@link MotionEvent} of the most recent gesture.
+     *
+     * Note that this may be the event prior to the last recorded event.
+     * @see #mDropLastEvent
+     */
     public MotionEvent getLastMotionEvent() {
         recalculateData();
         return mLastMotionEvent;
@@ -236,12 +260,13 @@ public class FalsingDataProvider {
             return;
         }
 
-        if (mRecentMotionEvents.isEmpty()) {
+        List<MotionEvent> recentMotionEvents = getRecentMotionEvents();
+        if (recentMotionEvents.isEmpty()) {
             mFirstRecentMotionEvent = null;
             mLastMotionEvent = null;
         } else {
-            mFirstRecentMotionEvent = mRecentMotionEvents.get(0);
-            mLastMotionEvent = mRecentMotionEvents.get(mRecentMotionEvents.size() - 1);
+            mFirstRecentMotionEvent = recentMotionEvents.get(0);
+            mLastMotionEvent = recentMotionEvents.get(recentMotionEvents.size() - 1);
         }
 
         calculateAngleInternal();
@@ -249,6 +274,17 @@ public class FalsingDataProvider {
         mDirty = false;
     }
 
+    private boolean shouldDropEvent(MotionEvent event) {
+        if (mRecentMotionEvents.size() < 3) return false;
+
+        MotionEvent lastEvent = mRecentMotionEvents.get(mRecentMotionEvents.size() - 1);
+        boolean isCompletingGesture = event.getActionMasked() == MotionEvent.ACTION_UP
+                && lastEvent.getActionMasked() == MotionEvent.ACTION_MOVE;
+        boolean isRecentEvent =
+                event.getEventTime() - lastEvent.getEventTime() < DROP_EVENT_THRESHOLD_MS;
+        return isCompletingGesture && isRecentEvent;
+    }
+
     private void calculateAngleInternal() {
         if (mRecentMotionEvents.size() < 2) {
             mAngle = Float.MAX_VALUE;
diff --git a/packages/SystemUI/src/com/android/systemui/classifier/TimeLimitedMotionEventBuffer.java b/packages/SystemUI/src/com/android/systemui/classifier/TimeLimitedMotionEventBuffer.java
index e5da38936593..addd8e26490a 100644
--- a/packages/SystemUI/src/com/android/systemui/classifier/TimeLimitedMotionEventBuffer.java
+++ b/packages/SystemUI/src/com/android/systemui/classifier/TimeLimitedMotionEventBuffer.java
@@ -183,7 +183,7 @@ public class TimeLimitedMotionEventBuffer implements List<MotionEvent> {
 
     @Override
     public List<MotionEvent> subList(int fromIndex, int toIndex) {
-        throw new UnsupportedOperationException();
+        return mMotionEvents.subList(fromIndex, toIndex);
     }
 
     class Iter implements ListIterator<MotionEvent> {
diff --git a/packages/SystemUI/tests/src/com/android/systemui/classifier/DistanceClassifierTest.java b/packages/SystemUI/tests/src/com/android/systemui/classifier/DistanceClassifierTest.java
index faa5db4327a6..ab6d5b771d5a 100644
--- a/packages/SystemUI/tests/src/com/android/systemui/classifier/DistanceClassifierTest.java
+++ b/packages/SystemUI/tests/src/com/android/systemui/classifier/DistanceClassifierTest.java
@@ -94,7 +94,9 @@ public class DistanceClassifierTest extends ClassifierTest {
         mClassifier.onTouchEvent(appendMoveEvent(1, 16, 3));
         mClassifier.onTouchEvent(appendMoveEvent(1, 17, 300));
         mClassifier.onTouchEvent(appendMoveEvent(1, 18, 301));
-        mClassifier.onTouchEvent(appendUpEvent(1, 19, 501));
+        mClassifier.onTouchEvent(appendMoveEvent(1, 19, 501));
+        mClassifier.onTouchEvent(appendUpEvent(1, 19, 501)); //event will be dropped
+
         assertThat(mClassifier.classifyGesture(0, 0.5, 1).isFalse()).isTrue();
     }
 
diff --git a/packages/SystemUI/tests/src/com/android/systemui/classifier/FalsingDataProviderTest.java b/packages/SystemUI/tests/src/com/android/systemui/classifier/FalsingDataProviderTest.java
index 2edc3d361316..8eadadff1ca5 100644
--- a/packages/SystemUI/tests/src/com/android/systemui/classifier/FalsingDataProviderTest.java
+++ b/packages/SystemUI/tests/src/com/android/systemui/classifier/FalsingDataProviderTest.java
@@ -75,16 +75,17 @@ public class FalsingDataProviderTest extends ClassifierTest {
     }
 
     @Test
-    public void test_trackMotionEvents() {
+    public void test_trackMotionEvents_dropUpEvent() {
         mDataProvider.onMotionEvent(appendDownEvent(2, 9));
         mDataProvider.onMotionEvent(appendMoveEvent(4, 7));
-        mDataProvider.onMotionEvent(appendUpEvent(6, 5));
+        mDataProvider.onMotionEvent(appendMoveEvent(6, 5));
+        mDataProvider.onMotionEvent(appendUpEvent(0, 0)); // event will be dropped
         List<MotionEvent> motionEventList = mDataProvider.getRecentMotionEvents();
 
         assertThat(motionEventList.size()).isEqualTo(3);
         assertThat(motionEventList.get(0).getActionMasked()).isEqualTo(MotionEvent.ACTION_DOWN);
         assertThat(motionEventList.get(1).getActionMasked()).isEqualTo(MotionEvent.ACTION_MOVE);
-        assertThat(motionEventList.get(2).getActionMasked()).isEqualTo(MotionEvent.ACTION_UP);
+        assertThat(motionEventList.get(2).getActionMasked()).isEqualTo(MotionEvent.ACTION_MOVE);
         assertThat(motionEventList.get(0).getEventTime()).isEqualTo(1L);
         assertThat(motionEventList.get(1).getEventTime()).isEqualTo(2L);
         assertThat(motionEventList.get(2).getEventTime()).isEqualTo(3L);
@@ -97,6 +98,28 @@ public class FalsingDataProviderTest extends ClassifierTest {
     }
 
     @Test
+    public void test_trackMotionEvents_keepUpEvent() {
+        mDataProvider.onMotionEvent(appendDownEvent(2, 9));
+        mDataProvider.onMotionEvent(appendMoveEvent(4, 7));
+        mDataProvider.onMotionEvent(appendUpEvent(0, 0, 100));
+        List<MotionEvent> motionEventList = mDataProvider.getRecentMotionEvents();
+
+        assertThat(motionEventList.size()).isEqualTo(3);
+        assertThat(motionEventList.get(0).getActionMasked()).isEqualTo(MotionEvent.ACTION_DOWN);
+        assertThat(motionEventList.get(1).getActionMasked()).isEqualTo(MotionEvent.ACTION_MOVE);
+        assertThat(motionEventList.get(2).getActionMasked()).isEqualTo(MotionEvent.ACTION_UP);
+        assertThat(motionEventList.get(0).getEventTime()).isEqualTo(1L);
+        assertThat(motionEventList.get(1).getEventTime()).isEqualTo(2L);
+        assertThat(motionEventList.get(2).getEventTime()).isEqualTo(100);
+        assertThat(motionEventList.get(0).getX()).isEqualTo(2f);
+        assertThat(motionEventList.get(1).getX()).isEqualTo(4f);
+        assertThat(motionEventList.get(2).getX()).isEqualTo(0f);
+        assertThat(motionEventList.get(0).getY()).isEqualTo(9f);
+        assertThat(motionEventList.get(1).getY()).isEqualTo(7f);
+        assertThat(motionEventList.get(2).getY()).isEqualTo(0f);
+    }
+
+    @Test
     public void test_trackRecentMotionEvents() {
         mDataProvider.onMotionEvent(appendDownEvent(2, 9, 1));
         mDataProvider.onMotionEvent(appendMoveEvent(4, 7, 800));
diff --git a/packages/SystemUI/tests/src/com/android/systemui/classifier/ZigZagClassifierTest.java b/packages/SystemUI/tests/src/com/android/systemui/classifier/ZigZagClassifierTest.java
index c343c20398e9..ae2b8bbb4ce6 100644
--- a/packages/SystemUI/tests/src/com/android/systemui/classifier/ZigZagClassifierTest.java
+++ b/packages/SystemUI/tests/src/com/android/systemui/classifier/ZigZagClassifierTest.java
@@ -68,6 +68,15 @@ public class ZigZagClassifierTest extends ClassifierTest {
     }
 
     @Test
+    public void testPass_dropClosingUpEvent() {
+        appendMoveEvent(0, 0);
+        appendMoveEvent(0, 100);
+        appendMoveEvent(0, 200);
+        appendUpEvent(0, 180); // this event would push us over the maxDevianceY
+        assertThat(mClassifier.classifyGesture(0, 0.5, 1).isFalse()).isFalse();
+    }
+
+    @Test
     public void testPass_fewTouchesHorizontal() {
         assertThat(mClassifier.classifyGesture(0, 0.5, 1).isFalse()).isFalse();
         appendMoveEvent(0, 0);