saving modified data in pdf itextsharp - itext

Question

I have created a pdf using itextsharp which contains some editable fields, when the service is called the pdf is created. But the problem what I am facing is, if i am changing anything in the pdf and downloading it then the changes are not saved. Also i want to open the pdf in a new tab through server side.
Code what I am using is:
public static String[] LANGUAGES_gc = { "English", "Math", "Science" };
[HttpGet]
[ODataRoute("GetPdf")]
public void DownloadPDF()
{
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;
PdfFormField field;
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(300, 806, 370, 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;
field = button.Field;
field.Action = PdfAction.JavaScript("this.showButtonState()", wri);
wri.AddAnnotation(field);
//}
//return ms.ToArray();
/*----------------------------------------------------*/
wri.AddAnnotation(_radioGroup);
wri.AddAnnotation(button.Field);
cb = wri.DirectContent;
doc.Close();
HttpContext.Current.Response.Write(doc);
HttpContext.Current.Response.End();
}
Can someone suggest me the solution??

Answer 1

Let's make an analogy here, with a simpler file-type. Suppose you're showing the user a textfile. They open it in their native .txt app (notepad) and make some changes.
Do you expect their changes to be communicated automatically back to your server?
Or that their changes are magically propagated? Of course not.
And even if it would, this seems like functionality notepad would have to provide, rather than something the creator of the file should do.
Now, as it so happens, there is a particular standard of pdf documents that exists for precisely your use-case. Essentially, the document sets up a connection to a server, and synchronizes. However, this standard is rather obscure, not a lot of viewers support it.
To the best of my knowledge, no pdf library (including iText) supports making documents like that.