public Caption PreviousCaption(Caption caption) { var idx = Captions.IndexOf(caption); if (idx == 0) { return(null); } return(Captions[idx - 1]); }
public Caption NextCaption(Caption caption) { var idx = Captions.IndexOf(caption); if (idx >= Captions.Count - 1) { return(null); } return(Captions[idx + 1]); }