ui/src/main/java/ucar/nc2/ui/image/ScalablePicture.java
public void sourceLoadProgressNotification(int statusCode, int percentage) {
    Enumeration e = scalablePictureStatusListeners.elements();
    while (e.hasMoreElements()) {
      ((ScalablePictureListener) e.nextElement())
          .sourceLoadProgressNotification(statusCode, percentage);
    }

  }
public void sourceLoadProgressNotification(int statusCode, int percentage) {
    Enumeration e = scalablePictureStatusListeners.elements();
    while (e.hasMoreElements()) {
      ((ScalablePictureListener) e.nextElement())
          .sourceLoadProgressNotification(statusCode, percentage);
    }

  }
pass on the update on the loading Progress to the listening objects