使用Itextsharp点击pdf处理按钮

Question

我使用ItextSharp创建了一个PDF，其中包含radio button和button。

我想在单击按钮时将整个PDF发送到服务，但无法获得如何处理事件。还有人可以建议我如何将按钮对齐到左下角。

我正在使用的代码是：

HttpContext.Current.Response.ContentType = "application/pdf";
HttpContext.Current.Response.AddHeader("content-disposition", "inline;filename=Example.pdf");
HttpContext.Current.Response.Cache.SetCacheability(HttpCacheability.NoCache);

Document doc = new Document(iTextSharp.text.PageSize.A4, 10f, 10f, 100f, 0f);
string pdfFilePath = HttpContext.Current.Server.MapPath(".") + "/PDFFiles";
PdfWriter wri = PdfWriter.GetInstance(doc, HttpContext.Current.Response.OutputStream);
doc.Open();
doc.AddAuthor("Test author");
doc.AddCreationDate();
PdfContentByte cb = wri.DirectContent;
Font _bf = new Font(Font.FontFamily.HELVETICA, 6);
PdfFormField _radioGroup = PdfFormField.CreateRadioButton(wri, true);
_radioGroup.FieldName = "language_gc";
Rectangle _rect;
RadioCheckField _radioG;
PdfFormField _radioField1;
for (int i = 0; i < LANGUAGES_gc.Length; i++)
{
    _rect = new Rectangle(46, 806 - i * 40, 60, 788 - i * 40);
    _radioG = new RadioCheckField(wri, _rect, null, LANGUAGES_gc[i]);
    _radioG.BackgroundColor = new GrayColor(0.8f);
    _radioG.BorderColor = GrayColor.BLACK;
    _radioG.CheckType = RadioCheckField.TYPE_CIRCLE;
    _radioField1 = _radioG.RadioField;
    _radioGroup.AddKid(_radioField1);              

    ColumnText.ShowTextAligned(cb, Element.ALIGN_LEFT, new Phrase(LANGUAGES_gc[i], new Font(Font.FontFamily.HELVETICA, 18)), 70, 790 - i * 40, 0);
}
/* Button */
_rect = new Rectangle(100, 806, 170, 788);
PushbuttonField button = new PushbuttonField(wri, _rect, "Buttons");
button.BackgroundColor = new GrayColor(0.75f);
button.BorderColor = GrayColor.GRAYBLACK;
button.BorderWidth = 1;
button.BorderStyle = PdfBorderDictionary.STYLE_BEVELED;
button.TextColor = GrayColor.GRAYBLACK;
button.FontSize = 12;
button.Text = "Submit";
button.Layout = PushbuttonField.LAYOUT_ICON_LEFT_LABEL_RIGHT;
button.ScaleIcon = PushbuttonField.SCALE_ICON_ALWAYS;
button.ProportionalIcon = true;
button.IconHorizontalAdjustment = 0;
/*----------------------------------------------------*/
wri.AddAnnotation(_radioGroup);
wri.AddAnnotation(button.Field);
cb = wri.DirectContent;
doc.Close();
HttpContext.Current.Response.Write(doc);
HttpContext.Current.Response.End();