code: public boolean dispatchTouchEvent(final MotionEvent event) {
      checkNotNull(event, "event == null");
      boolean isEventConsumed = false;
  
      switch (event.getAction()) {
        case MotionEvent.ACTION_DOWN: // user started touching the screen
          onActionDown(event);
          break;
        case MotionEvent.ACTION_UP:   // user stopped touching the screen
          isEventConsumed = onActionUp(event);
          break;
        case MotionEvent.ACTION_MOVE: // user is moving finger on the screen
          onActionMove(event);
          break;
        default:
          break;
      }
  
      return isEventConsumed;
    }
docs: Called to process touch screen events.
  
  @param event MotionEvent