Question

I have two PDF forms – an orignial form and a new form. The new form has x amount of extra acro fields on it, however it doesn’t have the original PDF fields.

I want to merge the fields from the old PDF to the new PDF form. The new field/fields would of moved some of the placeholders for the old fields so they may overlap or not be in the correct place, but this is irrelevant.

What I have tried

//Get the old PDF
PdfReader oldPdfReader = new PdfReader("Old.Pdf");
MemoryStream oldMs = new MemoryStream();
PdfStamper oldPdfStamper = new PdfStamper(oldPdfReader, oldMs);
//Get the new PDF
PdfReader newPdfReader = new PdfReader("New.Pdf");
MemoryStream newMs = new MemoryStream();
PdfStamper newPdfStamper = new PdfStamper(newPdfReader, newMs);

foreach(var oldField in oldPdfStamper.AcroFields.Fields)
{
   //Do a check to see if the field isn't already added
   if(!newPdfStamper.AcroFields.Fields.Any(x => x.Key == oldField.Key))
      newPdfStamper.AcroFields.Fields.Add(oldField);
}

This only outputs the new fields even though the debug hits the add, I have concluded this isn’t correct and I need to draw the fields on some how.

I have also tried the following example:

Merging multiple PDFs using iTextSharp in c#.net

It puts the new field on from New.PDF but doesn’t carry over the fields from Old.PDF. Any ideas on how I can merge the AcroFields from two PDF forms?

Answer 1

  //Get the old PDF
  PdfReader oldPdfReader = new PdfReader(@"old.pdf");
  MemoryStream oldMs = new MemoryStream();
  PdfStamper oldPdfStamper = new PdfStamper(oldPdfReader, oldMs);
  //Get the new PDF
  PdfReader newPdfReader = new PdfReader(@"new.pdf");
  MemoryStream newMs = new MemoryStream();
  PdfStamper newPdfStamper = new PdfStamper(newPdfReader, newMs);
  AcroFields af = oldPdfStamper.AcroFields;

  foreach (var oldField in oldPdfStamper.AcroFields.Fields)
  {
    var rectangles = af.GetFieldPositions(oldField.Key).Select(x => x.position.GetRectangle(x.position.Top, x.position.Bottom));
    foreach (var rectangle in rectangles)
    {
      TextField tf = new TextField(newPdfStamper.Writer, rectangle, oldField.Key);
      newPdfStamper.AddAnnotation(tf.GetTextField(), af.GetFieldPositions(oldField.Key).First().page);
    }
  }