Bloom.BookThumbNailer.GetThumbNailOfBookCover C# (CSharp) Method

        public void GetThumbNailOfBookCover(Book.Book book, HtmlThumbNailer.ThumbnailOptions thumbnailOptions, Action<Image> callback, Action<Exception> errorCallback, bool async)
        {
            if (book is ErrorBook)
            {
                callback(Resources.Error70x70);
                return;
            }
            try
            {
                if (book.HasFatalError) //NB: we might not know yet... we don't fully load every book just to show its thumbnail
                {
                    callback(Resources.Error70x70);
                    return;
                }
                Image thumb;
                if (book.Storage.TryGetPremadeThumbnail(thumbnailOptions.FileName, out thumb))
                {
                    callback(thumb);
                    return;
                }

                var dom = book.GetPreviewXmlDocumentForFirstPage();
                if (dom == null)
                {
                    callback(Resources.Error70x70);
                    return;
                }
                string folderForCachingThumbnail;

                folderForCachingThumbnail = book.Storage.FolderPath;
                _thumbnailProvider.GetThumbnail(folderForCachingThumbnail, book.Storage.Key, dom, thumbnailOptions, callback, errorCallback, async);
            }
            catch (Exception err)
            {
                callback(Resources.Error70x70);
                Debug.Fail(err.Message);
            }
        }