ITextSharp insert text to an existing pdf

I found a way to do it (dont know if it is the best but it works)

string oldFile = "oldFile.pdf";
string newFile = "newFile.pdf";


// open the reader
PdfReader reader = new PdfReader(oldFile);
Rectangle size = reader.GetPageSizeWithRotation(1);
Document document = new Document(size);


// open the writer
FileStream fs = new FileStream(newFile, FileMode.Create, FileAccess.Write);
PdfWriter writer = PdfWriter.GetInstance(document, fs);
document.Open();


// the pdf content
PdfContentByte cb = writer.DirectContent;


// select the font properties
BaseFont bf = BaseFont.CreateFont(BaseFont.HELVETICA, BaseFont.CP1252,BaseFont.NOT_EMBEDDED);
cb.SetColorFill(BaseColor.DARK_GRAY);
cb.SetFontAndSize(bf, 8);


// write the text in the pdf content
cb.BeginText();
string text = "Some random blablablabla...";
// put the alignment and coordinates here
cb.ShowTextAligned(1, text, 520, 640, 0);
cb.EndText();
cb.BeginText();
text = "Other random blabla...";
// put the alignment and coordinates here
cb.ShowTextAligned(2, text, 100, 200, 0);
cb.EndText();


// create the new page and add it to the pdf
PdfImportedPage page = writer.GetImportedPage(reader, 1);
cb.AddTemplate(page, 0, 0);


// close the streams and voilá the file should be changed :)
document.Close();
fs.Close();
writer.Close();
reader.Close();

I hope this can be usefull for someone =) (and post here any errors)

This worked for me and includes using OutputStream:

PdfReader reader = new PdfReader(new RandomAccessFileOrArray(Request.MapPath("Template.pdf")), null);
Rectangle size = reader.GetPageSizeWithRotation(1);
using (Stream outStream = Response.OutputStream)
{
Document document = new Document(size);
PdfWriter writer = PdfWriter.GetInstance(document, outStream);


document.Open();
try
{
PdfContentByte cb = writer.DirectContent;


cb.BeginText();
try
{
cb.SetFontAndSize(BaseFont.CreateFont(), 12);
cb.SetTextMatrix(110, 110);
cb.ShowText("aaa");
}
finally
{
cb.EndText();
}


PdfImportedPage page = writer.GetImportedPage(reader, 1);
cb.AddTemplate(page, 0, 0);


}
finally
{
document.Close();
writer.Close();
reader.Close();
}
}

In addition to the excellent answers above, the following shows how to add text to each page of a multi-page document:

 using (var reader = new PdfReader(@"C:\Input.pdf"))
{
using (var fileStream = new FileStream(@"C:\Output.pdf", FileMode.Create, FileAccess.Write))
{
var document = new Document(reader.GetPageSizeWithRotation(1));
var writer = PdfWriter.GetInstance(document, fileStream);


document.Open();


for (var i = 1; i <= reader.NumberOfPages; i++)
{
document.NewPage();


var baseFont = BaseFont.CreateFont(BaseFont.HELVETICA_BOLD, BaseFont.CP1252, BaseFont.NOT_EMBEDDED);
var importedPage = writer.GetImportedPage(reader, i);


var contentByte = writer.DirectContent;
contentByte.BeginText();
contentByte.SetFontAndSize(baseFont, 12);


var multiLineString = "Hello,\r\nWorld!".Split('\n');


foreach (var line in multiLineString)
{
contentByte.ShowTextAligned(PdfContentByte.ALIGN_LEFT, line, 200, 200, 0);
}


contentByte.EndText();
contentByte.AddTemplate(importedPage, 0, 0);
}


document.Close();
writer.Close();
}
}

Here is a method that uses stamper and absolute coordinates showed in the different PDF clients (Adobe, FoxIt and etc. )

public static void AddTextToPdf(string inputPdfPath, string outputPdfPath, string textToAdd, System.Drawing.Point point)
{
//variables
string pathin = inputPdfPath;
string pathout = outputPdfPath;


//create PdfReader object to read from the existing document
using (PdfReader reader = new PdfReader(pathin))
//create PdfStamper object to write to get the pages from reader
using (PdfStamper stamper = new PdfStamper(reader, new FileStream(pathout, FileMode.Create)))
{
//select two pages from the original document
reader.SelectPages("1-2");


//gettins the page size in order to substract from the iTextSharp coordinates
var pageSize = reader.GetPageSize(1);


// PdfContentByte from stamper to add content to the pages over the original content
PdfContentByte pbover = stamper.GetOverContent(1);


//add content to the page using ColumnText
Font font = new Font();
font.Size = 45;


//setting up the X and Y coordinates of the document
int x = point.X;
int y = point.Y;


y = (int) (pageSize.Height - y);


ColumnText.ShowTextAligned(pbover, Element.ALIGN_CENTER, new Phrase(textToAdd, font), x, y, 0);
}
}

Here is a method To print over images: taken from here. Use a different layer for your text you're putting over the images, and also make sure to use the GetOverContent() method.

            string oldFile = "FileWithImages.pdf";
string watermarkedFile = "Layers.pdf";
// Creating watermark on a separate layer
// Creating iTextSharp.text.pdf.PdfReader object to read the Existing PDF Document
PdfReader reader1 = new PdfReader(oldFile);
using (FileStream fs = new FileStream(watermarkedFile, FileMode.Create, FileAccess.Write, FileShare.None))
// Creating iTextSharp.text.pdf.PdfStamper object to write Data from iTextSharp.text.pdf.PdfReader object to FileStream object
using (PdfStamper stamper = new PdfStamper(reader1, fs))
{
// Getting total number of pages of the Existing Document
int pageCount = reader1.NumberOfPages;


// Create New Layer for Watermark
PdfLayer layer = new PdfLayer("Layer", stamper.Writer);
// Loop through each Page
for (int i = 1; i <= pageCount; i++)
{
// Getting the Page Size
Rectangle rect = reader1.GetPageSize(i);


// Get the ContentByte object
PdfContentByte cb = stamper.GetOverContent(i);


// Tell the cb that the next commands should be "bound" to this new layer
cb.BeginLayer(layer);
                    

BaseFont bf = BaseFont.CreateFont(BaseFont.HELVETICA, BaseFont.CP1252, BaseFont.NOT_EMBEDDED);
cb.SetColorFill(BaseColor.RED);
cb.SetFontAndSize(bf, 100);


cb.BeginText();
cb.ShowTextAligned(PdfContentByte.ALIGN_CENTER, "Some random blablablabla...", rect.Width / 2, rect.Height / 2, - 90);
cb.EndText();


// Close the layer
cb.EndLayer();
}
}