Rust

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.

Rust

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

let pdf = chilkat::Pdf::new();

// Load a PDF to be signed.
// The "hello.pdf" is available at https://chilkatsoft.com/hello.pdf
if pdf.load_file("qa_data/pdf/hello.pdf").is_err() {
    println!("{}", pdf.last_error_text());
    return;
}

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

// In most cases, the signingCertificateV2 and signingTime attributes are required.
let _ = json.update_int("signingCertificateV2", 1);
let _ = json.update_int("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.
let _ = json.update_int("page", pdf.num_pages());

// 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.
let _ = json.update_string("appearance.y", "bottom");
let _ = json.update_string("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.
let _ = json.update_string("appearance.fontScale", "9.0");

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

// Load the signing certificate. (Use your own certificate.)
let cert = chilkat::Cert::new();
if cert.load_pfx_file("qa_data/pfx/myPdfSigningCert.pfx", "pfx_password").is_err() {
    println!("{}", cert.last_error_text());
    return;
}

// Tell the pdf object to use the certificate for signing.
if pdf.set_signing_cert(&cert).is_err() {
    println!("{}", pdf.last_error_text());
    return;
}

if pdf.sign_pdf(&json, "qa_output/hello_signed.pdf").is_err() {
    println!("{}", pdf.last_error_text());
    return;
}

println!("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:

let _ = json.update_string("appearance.y", "792");
let _ = json.update_string("appearance.x", "0");

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

let pdf2 = chilkat::Pdf::new();
let _ = pdf2.load_file("qa_output/hello_signed.pdf").is_ok();
let _ = pdf2.set_signing_cert(&cert).is_ok();

if pdf2.sign_pdf(&json, "qa_output/hello_signed2.pdf").is_err() {
    println!("{}", pdf2.last_error_text());
    return;
}

println!("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)