iTextSharp Indic Text Rendering Issue

It seems I’m close to the solution for iTextSharp Indic Text Rendering Issue.
The only way to render Indic text by using Ligatures only.I will try come up with complete solution in next few weeks.(Few busy days to go).Existing ArabicLigature solution won’t help Indic text Rendering.

Check this pdf Embeded font: Gautami

Sample PDF Generated via iTextSharp having Complex Telugu Char

An intermediate way to generate Indic Pdf’s using iText/iTextsharp

An intermediate way to generate Indic Pdf’s using iText/iTextsharp


Introduction

I am working/dealing with Indic scripts for my project and I got so many problems due to partial/no support given by the s/w’s or Libraries/Languages/Frameworks. I tried to resolve my problems. One of them is generating PDF’s dynamically.

You know iTextSharp is a wonderful library for generating PDf Files dynamically. It supports unicode but not Indic Scripts. iText/iTextSharp has ready answer for this problem/bug/non support but not solution. I am not criticising iText/iTextsharp. Because it’s open source one can imporve it.

Background and Terms

I assume you have very basic idea/familier of iText/iTextSharp and GIST and these terms ISCII,Unicode,IsFoc.

My Intermediate Solution

Going Back to History.
I used GIST(Developed by CDAC) and ISCII.

  • Step1:
    • First you have to Convert the Unicode HTML String to ISCII HtmlString .
  • Step2:
    • Convert the ISCII string to ISFOC and Send this string to the iText HtmlParser
  • Step2 and Step3 can be merged by directly Converting Unicode string to ISFoc.This method is exposed by GIST. Can refer the GIST documentation
  • Step3:
    • Publish Pdf generated.

Step1

       public static string UniCode2ISCII(string  S)
    {

        if (S == null) { return null; }
        try
        {
            Encoding encFrom = Encoding.GetEncoding(57002);//Hindi
            //Encoding encFrom = Encoding.GetEncoding(57005);//Telugu

            Encoding encTo = Encoding.GetEncoding(1252);
            string str = S;
            Byte[] b = encFrom.GetBytes(str);
            return encTo.GetString(b);
        }
        catch { return null; }
    }

Step2

Public Class ISCII2ISFOC
     Declare Function Iscii2Isfoc Lib "ismapi32.dll" (ByVal s1 As String,
         ByVal s2 As String, ByVal ilen As Integer, ByVal sc As String) As Integer
    'Declare Function Isfoc2Iscii Lib "ismapi32.dll" (ByVal s1 As String,
       '  ByVal s2 As String, ByVal ilen As Integer, ByVal sc As String) As Integer
    'Declare Function Iscii2AccessIsfoc Lib "ismapi32.dll" (ByVal s1 As String,
        ' ByVal s2 As String, ByVal ilen As Integer, ByVal sc As String) As Integer
    ' sc = "DVB"   Devanagari  B-  Bilingial
    '                      Devanagari (DV - catering to Hindi, Marathi, etc.),
    '                     Gujarati (GJ), Kannada (KN), Malayalam (ML), Manipuri
    '                     (MN), Oriya (OR), Punjabi (PN), Tamil (TM), Telugu (TL)
                           

   Public Function ToIsfoc(ByVal str1 As String,ByVal sc as String ) As String
        Dim stext1 As String
        Dim ilen As Integer
        Dim iret As Integer
       stext1 = Space(str1.Length * 2) 'I Don't know   why it has to multiplied by 2
        ilen = str1.Length

        iret = Iscii2Isfoc(str1, stext1, ilen, sc)

        ToIsfoc = stext1

    End Function

End Class

Note:Above method is written in VB.Net So you have to Compile it as a seperate library and have to consume it.I tried with C# ref Variables.(Not got fruitful results. Needs to be written in C#.)

Step3

 //The  font name depends onthe Target Indic Language.  .. It can be made Dyanmic.
publc  void  PublishPdf(string IsFochtmlString){
        string htmlString = "<html><body><font face=\"DVBSR0XT.ttf\">" +
            IsFochtmlString+ "</font></body></html>";

        HttpRequest Request = System.Web.HttpContext.Current.Request;
        HttpResponse Response = System.Web.HttpContext.Current.Response;
        Response.Clear();
         Response.ContentType = "application/pdf";
        System.IO.MemoryStream m = new System.IO.MemoryStream();
        iTextSharp.text.Document document = new iTextSharp.text.Document();

        iTextSharp.text.pdf.PdfWriter writer =
            iTextSharp.text.pdf.PdfWriter.GetInstance(document, m);

        document.Open();

        System.Xml.XmlTextReader _xmlr = new System.Xml.XmlTextReader(
            new StringReader(htmlString));

        iTextSharp.text.html.HtmlParser.Parse(document, _xmlr);

        writer.Flush();

        Response.OutputStream.Write(m.GetBuffer(), 0, m.GetBuffer().Length);
        Response.OutputStream.Flush();
        Response.OutputStream.Close();
       Response.End();      }

Advantages

  • Compact and tiny compared with unicode.(Obviously.)

Limitations

  • It inherit’s the all limitations from ISCII .
  • It support’s Bilingual Only(i.e. English + the Indic Language).
  • It’s not the recommended way/It fails when there are multiple languages (Can overcome by splitting the String but It’s difficult at runtime but still one can try. It’s possible) because It can’t recognize the difference between the languages(Indic).

History

  • Article Raw Version 1 on 13 Aug 2008

Key words

iText Pdf Hindi,Telugu,Kannada,ISCII,ISFOC