@Override
  public void onImageDrawn(String id, INFO imageInfo, DimensionsInfo dimensionsInfo) {
    final int numberOfListeners = mListeners.size();
    for (int i = 0; i < numberOfListeners; ++i) {
      try {
        ControllerListener<? super INFO> listener = mListeners.get(i);
        if (listener instanceof OnDrawControllerListener) {
          ((OnDrawControllerListener) listener).onImageDrawn(id, imageInfo, dimensionsInfo);
        }
      } catch (Exception exception) {
        // Don't punish the other listeners if we're given a bad one.
        onException("InternalListener exception in onImageDrawn", exception);
      }
    }
  }
Listener that forwards controller events to multiple listeners.
drawee/src/main/java/com/facebook/drawee/controller/ForwardingControllerListener.java