Using iText to build PDF on the fly

Although there are many solutions (such as XML-FOP) to generate PDF on the fly, iText is a good choice to read PDF template and bind data dynamically.

1) For PDF form where data fields have fixed length, it is quite easy to use iText (I use C# version iTextSharp here) to bind data to PDF Text Field:

// Read PDF template
iTextSharp.text.pdf.PdfReader pdfRd = new iTextSharp.text.pdf.PdfReader(Server.MapPath("~/SampleJS.pdf"));
iTextSharp.text.pdf.PdfStamper stamp = new iTextSharp.text.pdf.PdfStamper(pdfRd, outputStream);

// Set form Text Fields
iTextSharp.text.pdf.AcroFields fields = stamp.AcroFields;
fields.SetField("formText", value);

// Close stamp

2) For free text data, you cannot put PDF Text Field to show data. For example, if you want to bind data to this template:

"Welcome to «Institution»! Please send mail to «Person» before «Date»"

You cannot use PDF Text Field because Text Field has fixed length. If «Institution» value is short, there will be extra blank space in the statement.

So what can you do? You can put the template statement into one Text Field with “Read Only” permission. Then you can replace the string with data like below:

// Get Text Fields from PDF file
iTextSharp.text.pdf.AcroFields fields = stamp.AcroFields;

// Get template
string formText = fields.GetField("formText");

// Replace template with data
formText = formText.Replace("«Institution»", txtInstitution);
formText = formText.Replace("«Person»", txtPerson);
formText = formText.Replace("«Date»", date);

// Set back the Text Field
fields.SetField("formText", formText);

3) How to insert image? PDF Text Field can be a placeholder for image. For example, to add a logo image to a placeholder:

// Get content to make changes
PdfContentByte overContent = stamp.GetOverContent(1);

// Get logo image
iTextSharp.text.Image logo = iTextSharp.text.Image.GetInstance(Server.MapPath("~/logo.jpg"));

// Get logo placeholder position
float[] logoArea = fields.GetFieldPositions("Logo");

// Get logo rectangle
iTextSharp.text.Rectangle logoRect = new Rectangle(logoArea[1], logoArea[2], logoArea[3], logoArea[4]);

// Set logo position in the placeholder (right alignment)
logo.ScaleToFit(logoRect.Width, logoRect.Height);
logo.SetAbsolutePosition(logoArea[3] - logo.ScaledWidth + (logoRect.Width - logo.ScaledWidth) / 2, logoArea[2] + (logoRect.Height - logo.ScaledHeight) / 2);

// Add image

4) How to add a barcode? Barcode is similar to image:

// Get content to make changes
PdfContentByte overContent = stamp.GetOverContent(1);

// Create a barcode
Barcode39 code39 = new Barcode39();
// Assign barcode value
code39.Code = barcodeValue;
code39.StartStopText = false;

// Create image from the barcode
iTextSharp.text.Image image39 = code39.CreateImageWithBarcode(overContent, null, null);

// Get barcode image placeholder
float[] barcodeArea = fields.GetFieldPositions("AppIDBarCode");
iTextSharp.text.Rectangle rect = new Rectangle(barcodeArea[1], barcodeArea[2], barcodeArea[3], barcodeArea[4]);
image39.ScaleToFit(rect.Width, rect.Height);
image39.SetAbsolutePosition(barcodeArea[1] + (rect.Width - image39.ScaledWidth) / 2, barcodeArea[2] + (rect.Height - image39.ScaledHeight) / 2);

// Add barcode image

I still have several issues to solve, such as how to put rich text into Text Field. But for now, I have a good start for PDF generation. :)

Relax with Taiji -- for programmers like me

I went to doctor's office this morning and saw a poster to prevent heart disease. It says right things like low-fat diet, no smoking, no alcohol, and regular exercise (with a gym picture). But one important point is missed -- Relax. :)

Everybody has experience of blood pressure difference when he/she is in anger and in sleep. Emotion is a big factor for health, so calm your body and mind down, and relax...

Who does not know how to relax?! "I can lie down on sofa and watch TV" ... Is that a good way to relax after sitting in front of computer for a whole day?

One old phrase says "People's leg gets old first". I am not so old, but my sensitive body is verifying it: After a whole day tiring computer work and when I use eyes to look at computer or TV at night, sometimes I even feel my eyes poll energy from feet to upper body! Our brain and eyes are consuming most of our energy everyday.

So to get heath back, we should:

1) Calm down eyes (no computer or TV) and mind (no work at home)
2) Exercise in slow motion to build energy
3) Let energy go down to get legs stronger

Those are some important values of Taiji to programmers.

If you have no chance to learn Taiji with a good teacher, you can relax by yourself: Stand still and calm your body down (for half an hour). You should feel your feet are heavy and your upper body is light -- that is also Taiji. :) Your feet are heavy because your body is relaxed and energy goes down. Gradually, your feet and legs will become stronger and healthier.

To Generate PDF on the fly

PDF is a standard format for B2B or B2C process these days. I think you may have tried to download bank statement in PDF format. On web sites, the PDF documents are generated on demand. They are not generated and saved somewhere ahead.

I am doing research on how to generate PDF on the fly. I tried some products on market, but I have not found any software that can do the job for me.

This is my requirement: I have some Word template documents with merge fields that can be used to bind database data to generate real documents.
  • I already have a back-end system to generate those Word documents and convert to PDF format to print
  • The front-end system also wants to generate PDF documents on the fly when user clicks a "Get PDF" button on web page
It is too slow to convert Word document to PDF format. For some relatively large document, it may take minutes to finish. This process can be used in back-end system asynchronously, but it is not for web site.

For web site, I have to use PDF forms with form fields to bind database data. I can use PDF editor software to add form fields. But if I create both Word templates and PDF forms, it is hard to maintain both versions.

Is there a software to convert Word templates to PDF forms and to convert Word merge fields to PDF form fields? I tried Adlib, Adobe, ActivePDf, even OpenOffice. Unfortunately, none of them can do merge field conversion.

Why did we use Word template in the beginning? Because Word is better than PDF editor in formatting, and also people are familiar with Word than PDf editor too.

So, it seems I have to create and maintain both Word template (for back-end system) and PDF form (for front-end system) versions. :(