public override void Draw(DrawContext context)
{
int pageNumber = GetOccupiedArea().GetPageNumber();
Rectangle bbox = GetInnerAreaBBox();
PdfDocument pdf = context.GetDocument();
PdfAcroForm form = PdfAcroForm.GetAcroForm(pdf, true);
PdfFormField chk = PdfFormField.CreateRadioButton(pdf, bbox, _group, _value, PdfAConformanceLevel.PDF_A_1B
);
chk.SetPage(pageNumber);
chk.SetValue("Off");
chk.RegenerateField();
chk.SetVisibility(PdfFormField.VISIBLE);
chk.SetBorderColor(ColorConstants.BLACK);
chk.SetBackgroundColor(ColorConstants.WHITE);
chk.SetReadOnly(true);
PdfFormXObject appearance = new PdfFormXObject(bbox);
PdfCanvas canvas = new PdfCanvas(appearance, pdf);
canvas.SaveState().MoveTo(bbox.GetLeft(), bbox.GetBottom()).LineTo(bbox.GetRight(), bbox.GetBottom()).LineTo
(bbox.GetRight(), bbox.GetTop()).LineTo(bbox.GetLeft(), bbox.GetTop()).LineTo(bbox.GetLeft(), bbox.GetBottom
()).SetLineWidth(1f).Stroke().RestoreState();
form.AddFieldAppearanceToPage(chk, pdf.GetPage(pageNumber));
chk.SetAppearance(PdfName.N, "v1".Equals(_value) ? _value : "Off", appearance.GetPdfObject());
}