void addFieldResources() throws IOException {
        if (fieldTemplates.isEmpty())
            return;
        PdfDictionary catalog = reader.getCatalog();
        PdfDictionary acroForm = (PdfDictionary)PdfReader.getPdfObject(catalog.get(PdfName.ACROFORM), catalog);
        if (acroForm == null) {
            acroForm = new PdfDictionary();
            catalog.put(PdfName.ACROFORM, acroForm);
            markUsed(catalog);
        }
        PdfDictionary dr = (PdfDictionary)PdfReader.getPdfObject(acroForm.get(PdfName.DR), acroForm);
        if (dr == null) {
            dr = new PdfDictionary();
            acroForm.put(PdfName.DR, dr);
            markUsed(acroForm);
        }
        markUsed(dr);
        for (PdfTemplate template: fieldTemplates) {
            PdfFormField.mergeResources(dr, (PdfDictionary)template.getResources(), this);
        }
        // if (dr.get(PdfName.ENCODING) == null) dr.put(PdfName.ENCODING, PdfName.WIN_ANSI_ENCODING);
        PdfDictionary fonts = dr.getAsDict(PdfName.FONT);
        if (fonts == null) {
            fonts = new PdfDictionary();
            dr.put(PdfName.FONT, fonts);
        }
        if (!fonts.contains(PdfName.HELV)) {
            PdfDictionary dic = new PdfDictionary(PdfName.FONT);
            dic.put(PdfName.BASEFONT, PdfName.HELVETICA);
            dic.put(PdfName.ENCODING, PdfName.WIN_ANSI_ENCODING);
            dic.put(PdfName.NAME, PdfName.HELV);
            dic.put(PdfName.SUBTYPE, PdfName.TYPE1);
            fonts.put(PdfName.HELV, addToBody(dic).getIndirectReference());
        }
        if (!fonts.contains(PdfName.ZADB)) {
            PdfDictionary dic = new PdfDictionary(PdfName.FONT);
            dic.put(PdfName.BASEFONT, PdfName.ZAPFDINGBATS);
            dic.put(PdfName.NAME, PdfName.ZADB);
            dic.put(PdfName.SUBTYPE, PdfName.TYPE1);
            fonts.put(PdfName.ZADB, addToBody(dic).getIndirectReference());
        }
        if (acroForm.get(PdfName.DA) == null) {
            acroForm.put(PdfName.DA, new PdfString("/Helv 0 Tf 0 g "));
            markUsed(acroForm);
        }
    }