使用itextsharp将HTML面板转换为pdf

Question

我试图将html面板转换为pdf面板包含面板和图像表 问题是当我按下按钮消息显示堆栈空

Protected Sub ShowPDF_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Try
            Response.ContentType = "application/pdf"
            Response.AddHeader("content-disposition", "attachment;filename=TestPage.pdf")
            Response.Cache.SetCacheability(HttpCacheability.NoCache)
            Dim sw As New StringWriter()
            Dim hw As New HtmlTextWriter(sw)
            Me.Page.RenderControl(hw)
            Dim sr As New StringReader(textConvert(sw.ToString()))
            Dim pdfDoc As New Document(PageSize.A4, 10.0F, 10.0F, 100.0F, 0.0F)
            Dim htmlparser As New HTMLWorker(pdfDoc)
            PdfWriter.GetInstance(pdfDoc, Response.OutputStream)
            pdfDoc.Open()
            htmlparser.Parse(sr)
            pdfDoc.Close()
            Response.Charset = Encoding.UTF8.ToString()
            Response.Write(pdfDoc)
            Response.[End]()
        Catch ex As Exception
            MsgBox(ex.Message))
        End Try
    End Sub