/**
  * Hide the graphic when the corresponding object was not detected. This can happen for
  * intermediate frames temporarily, for example if the object was momentarily blocked from view.
  */
 @Override
 public void onMissing(Detector.Detections<Barcode> detectionResults) {
   mOverlay.remove(mGraphic);
 }
 /**
  * Called when the item is assumed to be gone for good. Remove the graphic annotation from the
  * overlay.
  */
 @Override
 public void onDone() {
   mOverlay.remove(mGraphic);
 }
 /** Update the position/characteristics of the item within the overlay. */
 @Override
 public void onUpdate(Detector.Detections<Barcode> detectionResults, Barcode item) {
   mOverlay.add(mGraphic);
   mGraphic.updateItem(item);
 }