在页脚iTextShart中使用HTML

Question

我想在iTextShart 5.5.9的页脚中使用HTML。我花了几个小时找到例子，但注意到了作品。我使用IPdfPageEvent OnEndPage添加页脚。此示例有效但不是HTML：

        public void OnEndPage(PdfWriter writer, Document document)
        {
            var phrase = new Phrase("Footer");
            PdfContentByte cb = writer.DirectContent;
            ColumnText ct = new ColumnText(cb);
            ct.SetSimpleColumn(phrase, document.Left, document.GetBottom(50), document.Right, document.Bottom, 10, Element.ALIGN_CENTER);
            ct.Go();
        }

此示例应该能够处理HTML，工作（编译）但不显示页脚。我做错了什么？

public void OnEndPage(PdfWriter writer, Document document)
        {
            ColumnText ct = new ColumnText(writer.DirectContent);
            XMLWorkerHelper.GetInstance().ParseXHtml(new ColumnTextElementHandler(ct), new StringReader("Footer"));
            ct.SetSimpleColumn(document.Left, document.Top, document.Right, document.GetTop(-20), 10, Element.ALIGN_MIDDLE);
            ct.Go();
        }

        private class ColumnTextElementHandler : IElementHandler
        {
            public ColumnTextElementHandler(ColumnText ct)
            {
                _ct = ct;
            }

            private readonly ColumnText _ct;

            public void Add(IWritable w)
            {
                if (w is WritableElement)
                {
                    foreach (IElement e in ((WritableElement)w).Elements())
                    {
                        _ct.AddElement(e);
                    }
                }
            }
        }