[DO NOT MERGE] Transition to clear state after gesture cancelation.

The agreed-upon behavior has always been that after gesture cancelation, touch explorer would exist in essentially a dead state.
It should not be possible to execute a two-finger passthrough gesture for example after doing an invalid gesture.
This is likely why we see GESTURE_PASSTHROUGH in cases where we expect GESTURE_UNKNOWN.
Fix: 171421786
Bug: 162521649
Test: manual
Change-Id: Idce921c5278dea174ec5dad5cecf046f12ab113d

Change-Id: Ic71246adc613ea60d3f25974e4085814c4b3211d

services/accessibility/java/com/android/server/accessibility/gestures/GestureManifold.java

@@ -104,9 +104,9 @@ class GestureManifold implements GestureMatcher.StateChangeListener {
     // Shared state information.
     private TouchState mState;
 
-    GestureManifold(Context context, Listener listener, TouchState state) {
+    GestureManifold(Context context, Listener listener, TouchState state, Handler handler) {
         mContext = context;
-        mHandler = new Handler(context.getMainLooper());
+        mHandler = handler;
         mListener = listener;
         mState = state;
         mMultiFingerGesturesEnabled = false;

services/accessibility/java/com/android/server/accessibility/gestures/TouchExplorer.java

@@ -175,7 +175,7 @@ public class TouchExplorer extends BaseEventStreamTransformation
                 AccessibilityEvent.TYPE_TOUCH_INTERACTION_END,
                 mDetermineUserIntentTimeout);
         if (detector == null) {
-            mGestureDetector = new GestureManifold(context, this, mState);
+            mGestureDetector = new GestureManifold(context, this, mState, mHandler);
         } else {
             mGestureDetector = detector;
         }
@@ -353,7 +353,6 @@ public class TouchExplorer extends BaseEventStreamTransformation
     public boolean onGestureStarted() {
         // We have to perform gesture detection, so
         // clear the current state and try to detect.
-        mState.startGestureDetecting();
         mSendHoverEnterAndMoveDelayed.cancel();
         mSendHoverExitDelayed.cancel();
         mExitGestureDetectionModeDelayed.post();
@@ -1107,7 +1106,7 @@ public class TouchExplorer extends BaseEventStreamTransformation
     }
 
     private boolean shouldPerformGestureDetection(MotionEvent event) {
-        if (mState.isDelegating()) {
+        if (mState.isDelegating() || mState.isDragging()) {
             return false;
         }
         if (event.getActionMasked() == MotionEvent.ACTION_DOWN) {
@@ -1200,6 +1199,15 @@ public class TouchExplorer extends BaseEventStreamTransformation
         }
 
         public void run() {
+            if (mReceivedPointerTracker.getReceivedPointerDownCount() > 1) {
+                // Multi-finger touch exploration doesn't make sense.
+                Slog.e(
+                        LOG_TAG,
+                        "Attempted touch exploration with "
+                                + mReceivedPointerTracker.getReceivedPointerDownCount()
+                                + " pointers down.");
+                return;
+            }
             // Send an accessibility event to announce the touch exploration start.
             mDispatcher.sendAccessibilityEvent(
                     AccessibilityEvent.TYPE_TOUCH_EXPLORATION_GESTURE_START);

services/accessibility/java/com/android/server/accessibility/gestures/TouchState.java

@@ -208,7 +208,9 @@ public class TouchState {
                 startGestureDetecting();
                 break;
             case AccessibilityEvent.TYPE_GESTURE_DETECTION_END:
-                startTouchInteracting();
+                // Clear to make sure that we don't accidentally execute passthrough, and that we
+                // are ready for the next interaction.
+                clear();
                 break;
             default:
                 break;

services/tests/servicestests/src/com/android/server/accessibility/gestures/GestureManifoldTest.java

@@ -26,6 +26,7 @@ import android.accessibilityservice.AccessibilityService;
 import android.content.Context;
 import android.graphics.Point;
 import android.graphics.PointF;
+import android.os.Handler;
 import android.view.MotionEvent;
 
 import androidx.test.InstrumentationRegistry;
@@ -56,7 +57,8 @@ public class GestureManifoldTest {
         // Construct a testable GestureManifold.
         mResultListener = mock(GestureManifold.Listener.class);
         mState = new TouchState();
-        mManifold = new GestureManifold(context, mResultListener, mState);
+        Handler handler = new Handler(context.getMainLooper());
+        mManifold = new GestureManifold(context, mResultListener, mState, handler);
         // Play the role of touch explorer in updating the shared state.
         when(mResultListener.onGestureStarted()).thenReturn(onGestureStarted());