iTextSharp.text.pdf.AcroFields.GetAppearance C# (CSharp) Метод

        internal PdfAppearance GetAppearance(PdfDictionary merged, String text, String fieldName) {
            topFirst = 0;
            TextField tx = null;
            if (fieldCache == null || !fieldCache.ContainsKey(fieldName)) {
                tx = new TextField(writer, null, null);
                tx.SetExtraMargin(extraMarginLeft, extraMarginTop);
                tx.BorderWidth = 0;
                tx.SubstitutionFonts = substitutionFonts;
                DecodeGenericDictionary(merged, tx);
                //rect
                PdfArray rect = merged.GetAsArray(PdfName.RECT);
                Rectangle box = PdfReader.GetNormalizedRectangle(rect);
                if (tx.Rotation == 90 || tx.Rotation == 270)
                    box = box.Rotate();
                tx.Box = box;
                if (fieldCache != null)
                    fieldCache[fieldName] = tx;
            }
            else {
                tx = (TextField)fieldCache[fieldName];
                tx.Writer = writer;
            }
            PdfName fieldType = merged.GetAsName(PdfName.FT);
            if (PdfName.TX.Equals(fieldType)) {
                tx.Text = text;
                return tx.GetAppearance();
            }
            if (!PdfName.CH.Equals(fieldType))
                throw new DocumentException("An appearance was requested without a variable text field.");
            PdfArray opt = merged.GetAsArray(PdfName.OPT);
            int flags = 0;
            PdfNumber nfl = merged.GetAsNumber(PdfName.FF);
            if (nfl != null)
                flags = nfl.IntValue;
            if ((flags & PdfFormField.FF_COMBO) != 0 && opt == null) {
                tx.Text = text;
                return tx.GetAppearance();
            }
            if (opt != null) {
                String[] choices = new String[opt.Size];
                String[] choicesExp = new String[opt.Size];
                for (int k = 0; k < opt.Size; ++k) {
                    PdfObject obj = opt[k];
                    if (obj.IsString()) {
                            choices[k] = choicesExp[k] = ((PdfString)obj).ToUnicodeString();
                    }
                    else {
                        PdfArray a = (PdfArray) obj;
                        choicesExp[k] = a.GetAsString(0).ToUnicodeString();
                        choices[k] = a.GetAsString(1).ToUnicodeString();
                    }
                }
                if ((flags & PdfFormField.FF_COMBO) != 0) {
                    for (int k = 0; k < choices.Length; ++k) {
                        if (text.Equals(choicesExp[k])) {
                            text = choices[k];
                            break;
                        }
                    }
                    tx.Text = text;
                    return tx.GetAppearance();
                }
                int idx = 0;
                for (int k = 0; k < choicesExp.Length; ++k) {
                    if (text.Equals(choicesExp[k])) {
                        idx = k;
                        break;
                    }
                }
                tx.Choices = choices;
                tx.ChoiceExports = choicesExp;
                tx.ChoiceSelection = idx;
            }
            PdfAppearance app = tx.GetListAppearance();
            topFirst = tx.TopFirst;
            return app;
        }