iText Android - Adding text to existing PDF

Question

we have a PDF with some fields in order to collect some data, and I have to fill it programmatically with iText on Android by adding some text in those positions. I've been thinking about different ways to achieve this, with little success in each one.

Note: I'm using the Android version of iText (iTextG 5.5.4) and a Samsung Galaxy Note 10.1 2014 (Android 4.4) for most of my tests.

• The approach I took from the start was to "draw" the text on a given coordinates, for a given page. This has some problems with the management of the fields (I have to be aware of the length of the strings, and it could be hard to position each text in the exact coordinate of the pdf). But most importantly, the performance of the process is really slow in some devices/OSVersions (it works great in Nexus 5 with 5.0.2, but takes several minutes with a 5MB Pdf on the Note 10.1).

      pdfReader = new PdfReader(is);
  
      document = new Document();
  
      ByteArrayOutputStream baos = new ByteArrayOutputStream();
      pdfCopy = new PdfCopy(document, baos);
      document.open();
  
      PdfImportedPage page;
      PdfCopy.PageStamp stamp;
  
      for (int i = 1; i <= pdfReader.getNumberOfPages(); i++) {
  
          page = pdfCopy.getImportedPage(pdfReader, i); // First page = 1
          stamp = pdfCopy.createPageStamp(page);
  
          for (int i=0; i<10; i++) {
              int posX = i*50;
              int posY = i*100;
              Phrase phrase = new Phrase("Example text", FontFactory.getFont(FontFactory.HELVETICA, 12, BaseColor.RED));
              ColumnText.showTextAligned(stamp.getOverContent(), Element.ALIGN_CENTER, phrase, posX, posY, 0);
          }
  
          stamp.alterContents();
          pdfCopy.addPage(page);
      }
  

• We though about adding "forms fields" instead of drawing. That way I can configure a TextField and avoid managing the texts myself. However, the final PDF shouldn't have any annotations, so I would need to copy it into a new Pdf without annotations and with those "forms fields" drawn. I don't have an example of this because I wasn't able to perform this, I don't even know if this is possible/worthwhile.

• The third option would be to receive a Pdf with the "forms fields" already added, that way I only have to fill them. However I still need to create a new Pdf with all those fields and without annotations...

I'd like to know what's be the best way in performance to do this process, and any help about achieving it. I am really newbie with iText and any help would be really appreciated.

Thanks!

EDIT

At the end I used the third option: a PDF with editable fields that we fill, and then we use the "flattening" to create a non-editable PDF with all texts already there.

The code is as follows:

    pdfReader = new PdfReader(is);

    FileOutputStream fios = new FileOutputStream(outPdf);

    PdfStamper pdfStamper = new PdfStamper(pdfReader, fios);
    //Filling the PDF (It's totally necessary that the PDF has Form fields)
    fillPDF(pdfStamper);
    //Setting the PDF to uneditable format
    pdfStamper.setFormFlattening(true);

    pdfStamper.close();

and the method to fill the forms:

public static void fillPDF(PdfStamper stamper) throws IOException, DocumentException{
    //Getting the Form fields from the PDF
    AcroFields form = stamper.getAcroFields();
    Set<String> fields = form.getFields().keySet();
    for(String field : fields){
            form.setField("name", "Ernesto");
            form.setField("surname", "Lage");
        }
    }
}

The only thing about this approach is that you need to know the name of each field in order to fill it.

Answer 1

There is a process in iText known as 'flattening', which takes the form fields, and replaces them with the text that the fields contain.

I haven't used iText in a few years (and not at all on Android), but if you search the manual or online examples for 'flattening', you should find how to do it.