Add Javascript to PDF file using iText7 C#

Question

I am trying to add javascript to my PDF file using iText7 library and C#

Currently, here is my code...which is by far not finish yet

public FileResult Download(string id)
    {
        var fileSelect = _context.FileStores.SingleOrDefault(c => c.File_Id == id);
        
        string base64string = Convert.ToBase64String(fileSelect.File_Content, 0, fileSelect.File_Content.Length);


        using (MemoryStream stream = new System.IO.MemoryStream())
        {

            MemoryStream memory = new MemoryStream(fileSelect.File_Content);
            BinaryReader BRreader = new BinaryReader(memory);
            StringBuilder text = new StringBuilder();


            PdfReader reader = new PdfReader(memory);
            //FileStream output = new FileStream(@"Manual.pdf", FileMode.Create);

            PdfDocument Pdfdoc = new PdfDocument(reader);
            Document doc = new Document(Pdfdoc);
            PdfAction action = PdfAction.CreateJavaScript("var rightNow = new Date(); " +
                                                          "var endDate = new Date('May 03, 2021 10:00:00');" +
                                                          "if(rightNow.getTime() > endDate){" +
                                                          "app.alert('This Document has expired, please contact us for a new one');" +
                                                          "this.closeDoc();}");
            reader.Close();

            return File(memory, "application/pdf", "ExportData.pdf");
        }

I want to add this javascript to my PDF and also download the file after it is finished adding the Javascript. Is there anybody that knows how to add Javascript to pdf? thanks

As an aside: You are aware that such a script is trivial to circumvent? — mkl
– mkl, Commented May 3, 2021 at 8:26
yes @mkl, I am trying to see if it's possible to implement it like acrobat — Iman Manan
– Iman Manan, Commented May 3, 2021 at 8:52

rhens · Accepted Answer · 2021-05-03 19:33:40Z

2

You can add the Javascript snippet as a document level OpenAction, to be executed when the document is opened:

PdfReader reader = new PdfReader("input.pdf");
PdfWriter writer = new PdfWriter("output.pdf");

PdfDocument Pdfdoc = new PdfDocument(reader, writer);
PdfAction action = PdfAction.CreateJavaScript(
    "var rightNow = new Date(); " +
    "var endDate = new Date('May 03, 2021 10:00:00');" +
    "if(rightNow.getTime() > endDate){" +
    "app.alert('This Document has expired, please contact us for a new one');" +
    "this.closeDoc();}"
);
Pdfdoc.getCatalog().SetOpenAction(action);
Pdfdoc.Close();

answered May 3, 2021 at 19:33

rhens

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2 Comments

Iman Manan Over a year ago

Hey man @rhens, thank alot! This does the job!... by any chance, do you know how to implement a download feature where the user can choose the path where he/she want to save the file?

rhens Over a year ago

I'm not sure downloading and saving, through Javascript, from within the PDF viewer, will be possible. You could open a URL and handle the file saving through the browsers: app.launchURL('https://URL/to/your/PDF'); Regardless, be prepared to run into security issues, possible depending on the configuration of the PDF viewer.

bgh · Accepted Answer · 2022-03-25 11:56:53Z

0

The following code worked for me. Multiple scripts can be added to the same document this way.

using var pdfReader = new PdfReader("input.pdf");
using var outputStream = new FileStream("output.pdf", FileMode.Create);
using var pdfWriter = new PdfWriter(outputStream);
using var outputPdfDocument = new PdfDocument(pdfReader, pdfWriter);

var outputJavaScriptNameTree = outputPdfDocument.GetCatalog().GetNameTree(PdfName.JavaScript);
outputJavaScriptNameTree.AddEntry(
    "Script1",
    PdfAction.CreateJavaScript("app.alert('Hello world!');").GetPdfObject());

answered Mar 25, 2022 at 11:56

bgh

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