code: public void cancel() {
          mActivePointerId = INVALID_POINTER;
          clearMotionHistory();
  
          if (mVelocityTracker != null) {
              mVelocityTracker.recycle();
              mVelocityTracker = null;
          }
      }
docs: The result of a call to this method is equivalent to
  {@link #processTouchEvent(android.view.MotionEvent)} receiving an ACTION_CANCEL event.