public ActionResult GetThumbnail(string fileId, long size) { var guid = Guid.Parse(fileId); var thumbnail = _filesStorage.GetThumbnail(guid); if (thumbnail != null) { return(File(thumbnail, "image/png")); } var actor = _contextService.GetTokenActor(HttpContext); var fileLoader = _contextService.GetFileLoader(actor); var fileContent = fileLoader.Download(guid, size); thumbnail = _documentRender.RenderPage(fileContent, 1, 0.2); if (thumbnail != null) { _fileSaver.PutThumbnailAsync(guid, thumbnail); } return(File(thumbnail, "image/png")); }