this one
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// Instantiate an object PDF class
Aspose.Pdf.Generator.Pdf pdf = new Aspose.Pdf.Generator.Pdf();
// add the section to PDF document sections collection
Aspose.Pdf.Generator.Section section = pdf.Sections.Add();
// Read the contents of HTML file into StreamReader object
StreamReader r = File.OpenText(@“D:/pdftest/HTML2pdf.html”);
//Create text paragraphs containing HTML text
Aspose.Pdf.Generator.Text text2 = new Aspose.Pdf.Generator.Text(section, r.ReadToEnd());
// enable the property to display HTML contents within their own formatting
text2.IsHtmlTagSupported = true;
//Add the text paragraphs containing HTML text to the section
section.Paragraphs.Add(text2);
// Specify the URL which serves as images database
pdf.HtmlInfo.ImgUrl = “D:/pdftest/MemoryStream/”;
//Save the pdf document
pdf.Save(“D:/pdftest/MemoryStream/HTML2pdf.pdf”);
and that one 
// The address of the web URL which you need to convert into PDF format
string WebUrl = “http://en.wikipedia.org/wiki/Main_Page”;
// create a Web Request object to connect to remote URL
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(WebUrl);
// set the Web Request timeout
request.Timeout = 10000; // 10 secs
// Retrieve request info headers
HttpWebResponse localWebResponse = (HttpWebResponse)request.GetResponse();
// Windows default Code Page (Include System.Text namespace in project)
Encoding encoding = Encoding.GetEncoding(1252);
// Read the contents of into StreamReader object
StreamReader localResponseStream = new StreamReader(localWebResponse.GetResponseStream(), encoding);
// Instantiate an object PDF class
Aspose.Pdf.Generator.Pdf pdf = new Aspose.Pdf.Generator.Pdf();
// add the section to PDF document sections collection
Aspose.Pdf.Generator.Section section = pdf.Sections.Add();
//Create text paragraphs containing HTML text
Aspose.Pdf.Generator.Text text2 = new Aspose.Pdf.Generator.Text(section, localResponseStream.ReadToEnd());
// enable the property to display HTML contents within their own formatting
text2.IsHtmlTagSupported = true;
// Add the text object containing HTML contents to PD Sections
section.Paragraphs.Add(text2);
// Specify the URL which serves as images database
//pdf.HtmlInfo.ImgUrl = “http://en.wikipedia.org/”;
//Save the pdf document
pdf.Save(“D:/pdftest/DirectHTML2pdf.pdf”);
localWebResponse.Close();
localResponseStream.Close()
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generate an empty PDF file …
why ?