Insert an Image in PDF using ITextSharp - itext

Question

I have to insert a an image in a pdf. That is, wherever I see a text 'Signature', I have to insert an signature image there . I can do by saying absolute positions .
But, I am looking for how to find the position of the word 'Signature' in the pdf and insert the image.
Appreciate ur help!
This is the working code:
using (Stream inputImageStream = new FileStream(#"C:\signature.jpeg", FileMode.Open, FileAccess.Read, FileShare.Read))
using (Stream outputPdfStream = new FileStream(#"C:\test\1282011\Result.pdf", FileMode.Create, FileAccess.Write, FileShare.None))
{
var reader = new PdfReader(#"C:\Test\1282011\Input.pdf");
var stamper = new PdfStamper(reader, outputPdfStream);
var count = reader.NumberOfPages;
iTextSharp.text.Image image = iTextSharp.text.Image.GetInstance(inputImageStream);
image.SetAbsolutePosition(300, 200); // Absolute position
image.ScaleToFit(200, 30);
PRTokeniser pkt = null;
string strpages = string.Empty;
System.Text.StringBuilder build = new System.Text.StringBuilder();
for (int i = 1; i <= count; i++)
{
var pdfContentByte = stamper.GetOverContent(i);
if (pdfContentByte != null)
{
pkt = new PRTokeniser(stamper.Reader.GetPageContent(i));
while (pkt.NextToken())
{
if (pkt.TokenType == PRTokeniser.TokType.STRING)
{
if (pkt.StringValue == "Signature")
{
pdfContentByte.AddImage(image);
}
}
}
}
}
stamper.Close();
}
}
After some googling, I found out that I could absolute position of text as follows:
extSharp.text.pdf.AcroFields fields = stamper.AcroFields;
IList<iTextSharp.text.pdf.AcroFields.FieldPosition> signatureArea = fields.GetFieldPositions("Signature");
iTextSharp.text.Rectangle rect= signatureArea.First().position;
iTextSharp.text.Rectangle logoRect = new iTextSharp.text.Rectangle(rect);
image.SetAbsolutePosition(logoRect.Width ,logoRect .Height );
But the variable , signatureArea is null all the time even when the pdf contains the word 'Signature'.
Any input..? :)
Jaleel

Answer 1

Check out PdfTextExtractor and specifically the LocationTextExtractionStrategy. Create a class in your project with the exact code for the LocationTextExtractionStrategy and put a breakpoint on the line return sb.ToString(); (line 131 in SVN) and take a look at the contents of the variable locationalResult. You'll see pretty much exactly what you're looking for, a collection of text with start and end locations. If your search word isn't on a line by itself you might have to dig a little deeper but this should point you in the right direction.

Answer 2

That was perfect Chris. I am able to find the text position and insert the signature. What I understood is , there is a list List<TextChunk> LocationalResult in the LocationTextExtractionStrategy class. The RenderText() method in LocationTextExtractionStrategy will add each text to the LocationalResult list.
Actually the list LocationalResult is a private list, I made it public to access it from outside.
I loop through each page of PDF document and call PdfTextExtractor.GetTextFromPage(reader, i, locationStrat); where i is the pagenumber. At this time all text in the page will be added to the LocationalResult with all the position information.
This is what I done . And it works perfect.