c# - Set different parts of a form field to have different fonts using iTextSharp

Question

I'm not sure that this is possible but I figured it would be worth asking. I have figured out how to set the font of a formfield using the pdfstamper and acrofields methods but I would really like to be able to set the font of different parts of the text in the same field. Here's how I'm setting the font of the form fields currently:

            // Use iTextSharp PDF Reader, to get the fields and send to the 
            //Stamper to set the fields in the document
            PdfReader pdfReader = new PdfReader(fileName);

            // Initialize Stamper (ms is a MemoryStream object)
            PdfStamper pdfStamper = new PdfStamper(pdfReader, ms);

            // Get Reference to PDF Document Fields
            AcroFields pdfFormFields = pdfStamper.AcroFields;

            //create a bold font
            iTextSharp.text.Font bold = FontFactory.GetFont(FontFactory.COURIER, 8f, iTextSharp.text.Font.BOLD);

            //set the field to bold
            pdfFormFields.SetFieldProperty(nameOfField, "textfont", bold.BaseFont, null);

            //set the text of the form field
            pdfFormFields.SetField(nameOfField, "This:  Will Be Displayed In The Field");

           // Set the flattening flag to false, so the document can continue to be edited
            pdfStamper.FormFlattening = true;

            // close the pdf stamper
            pdfStamper.Close();

What I'd like to be able to do where I set the text above is set the "This: " to bold and leave the "Will Be Displayed In The Field" non-bolded. I'm not sure this is actually possible but I figured it was worth asking because it would really be helpful in what I'm currently working on.

Thanks in advance!

Answer 1

Yes, kinda. PDF fields can have a rich text value (since acrobat 6/pdf1.5) along with a regular value.

The regular value uses the font defined in the default appearances... a single font.

The rich value format (which iText doesn't support directly, at least not yet), is described in chapter 12.7.3.4 of the PDF Reference. <b>, <i>, <p>, and quite a few css2 text attributes. It requires a with various attributes.

To enable rich values, you have to set bit 26 of the field flags (PdfName.FF) for a text field. PdfFormField doesn't have a "setRichValue", but they're dictionaries, so you can just:

myPdfFormField.put(PdfName.RV, new PdfString( richTextValue ) );

If you're trying to add rich text to an existing field that doesn't already support it:

AcroFields fields = stamper.getAcroFields();

AcroFields.Item fldItem = fields.getFieldItem(fldName);
PdfDictionary mergedDict = item.getMerged(0);
int flagVal = mergedDict.getAsNumber(PdfName.FF).intValue();
flagVal |= (1 << 26);

int writeFlags = AcroFields.Item.WRITE_MERGED | AcroFields.Item.WRITE_VALUE;
fldItem.writeToAll(PdfName.FF, new PdfNumber(flagVal), writeFlags);
fldItem.writeToAll(PdfName.RV, new PdfString(richTextValue), writeFlags);

I'm actually adding rich text support to iText (not sharp) as I type this message. Hurray for contributors on SO. Paulo's been good about keeping iTextSharp in synch lately, so that shouldn't be an issue. The next trunk release should have this feature... so you'd be able to write:

myPdfFormField.setFieldFlags( PdfFormField.FF_RICHTEXT );
myPdfFormField.setRichValue( richTextValue );

or

// note that this will fail unless the rich flag is set
acroFields.setFieldRichValue( richTextValue );

NOTE: iText's appearance generation hasn't been updated, just the value side of things. That would take considerably more work. So you'll want to acroFields.setGenerateAppearances(false) or have JS that resets the field value when the form its opened to force Acrobat/Reader to build the appearance[s] for you.