Node.js

PDF Signature Page Location

See more PDF Signatures Examples

This example demonstrates how to specify the location of a PDF signature on a page.

Note: This example requires Chilkat v9.5.0.85 or greater.

Node.js

NODEJS_PRELUDE

function chilkatExample() {

    var success = false;

    //  This example requires the Chilkat API to have been previously unlocked.
    //  See Global Unlock Sample for sample code.

    var pdf = new chilkat.Pdf();

    //  Load a PDF to be signed.
    //  The "hello.pdf" is available at https://chilkatsoft.com/hello.pdf
    success = pdf.LoadFile("qa_data/pdf/hello.pdf");
    if (success == false) {
        console.log(pdf.LastErrorText);
        return;
    }

    //  Options for signing are specified in JSON.
    var json = new chilkat.JsonObject();

    //  In most cases, the signingCertificateV2 and signingTime attributes are required.
    json.UpdateInt("signingCertificateV2",1);
    json.UpdateInt("signingTime",1);

    //  When cryptographically signing a PDF, the signature's appearance can be placed on a specific
    //  page in the PDF document, and at a specified location on the page.
    //  The 1st page of the PDF document is page number 1 (we don't use 0-based numbering for PDF page numbers).
    //  The PDF object has a NumPages property, so we can use it to sign on the last page of the PDF.
    json.UpdateInt("page",pdf.NumPages);

    //  appearance.y and appearance.x JSON properties control the x,y location of the signature.
    //  The "appearance.y" can be "top" or "bottom".
    //  The "appearance.x" can be "left", "middle", or "right".
    //  It is also possible to specify exact PDF location in user space coordinates, which is discussed below.
    json.UpdateString("appearance.y","bottom");
    json.UpdateString("appearance.x","middle");

    //  In this example, the fontScale (in combination with the number of appearance text lines and the length of the longest text line),
    //  automatically determine the width/height of the signature text box. Any included graphic (JPG image or built-in SVG) is automatically
    //  scaled to fit. It is alternatively possible to specify the desired width/height of the signature rectangle.  In that case
    //  you would NOT specify a fontScale because Chilkat would automatically chose a font scale to fit the text to the desired rectangle.
    //  This example demonstrates how to specify the exact width/height of the PDF signature text box.
    json.UpdateString("appearance.fontScale","9.0");

    json.UpdateString("appearance.text[0]","Digitally signed by: cert_cn");
    json.UpdateString("appearance.text[1]","current_dt");
    json.UpdateString("appearance.image","document-accepted");
    json.UpdateString("appearance.imagePlacement","left");
    json.UpdateString("appearance.imageOpacity","100");

    //  Load the signing certificate. (Use your own certificate.)
    var cert = new chilkat.Cert();
    success = cert.LoadPfxFile("qa_data/pfx/myPdfSigningCert.pfx","pfx_password");
    if (success == false) {
        console.log(cert.LastErrorText);
        return;
    }

    //  Tell the pdf object to use the certificate for signing.
    success = pdf.SetSigningCert(cert);
    if (success == false) {
        console.log(pdf.LastErrorText);
        return;
    }

    success = pdf.SignPdf(json,"qa_output/hello_signed.pdf");
    if (success == false) {
        console.log(pdf.LastErrorText);
        return;
    }

    console.log("The PDF has been successfully cryptographically signed.");

    //  The appearance of the signature appears in Adobe Acrobat as shown here:

    //  ----------------------------------------------------------------------------------------------------
    //  *** Scroll down for information about specifying the PDF signature x,y location in user space coordinates.
    //  ----------------------------------------------------------------------------------------------------

    //  (image:https://example-code.com/images/bottom_middle_signature.jpg/endImage)

    //  The x,y coordinates of a PDF page are in "user space", called "points", and there are 72 pointes per inch.
    //  A PDF page (8.5" x 11") is 612 points wide and 792 points high.
    //  The bottom left is at 0,0.    The top right is at 612,792.
    //  
    //  To specify the location of a signature rectangle, the "appearance.y" is the y coordinate of the top of the signature rectangle,
    //  and the "appearance.x" is the x coordinate of the left of the signature rectangle.
    //  Therefore, to position the signature rectangle at the exact top/left of the page, we do this:

    json.UpdateString("appearance.y","792");
    json.UpdateString("appearance.x","0");

    json.UpdateString("appearance.text[0]","Digitally signed again by: cert_cn");
    json.UpdateString("appearance.text[1]","current_dt");
    json.UpdateString("appearance.image","document-accepted");
    json.UpdateString("appearance.imagePlacement","right");

    var pdf2 = new chilkat.Pdf();
    success = pdf2.LoadFile("qa_output/hello_signed.pdf");
    success = pdf2.SetSigningCert(cert);

    success = pdf2.SignPdf(json,"qa_output/hello_signed2.pdf");
    if (success == false) {
        console.log(pdf2.LastErrorText);
        return;
    }

    console.log("The PDF has been successfully cryptographically signed again.");

    //  Here we have the PDF with the signature just added at the exact top/left.
    //  (image:https://example-code.com/images/pdf_signature_top_left.jpg/endImage)

}

chilkatExample();