C#

PDF Signature Appearance Width and Height

See more PDF Signatures Examples

This example explains how the width and height of the signature appearance rectangle box is determined. C#

bool success = false;

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

Chilkat.Pdf 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) {
    Debug.WriteLine(pdf.LastErrorText);
    return;
}

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

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

//  Put the signature on page 1, top left
json.UpdateInt("page",1);
json.UpdateString("appearance.y","top");
json.UpdateString("appearance.x","left");

//  Add some text.
json.UpdateString("appearance.text[0]","Digitally signed by: cert_cn");
json.UpdateString("appearance.text[1]","current_dt");

//  Add a built-in SVG graphic to the right.
json.UpdateString("appearance.image","blue-check-mark");
json.UpdateString("appearance.imagePlacement","right");
json.UpdateString("appearance.imageOpacity","100");

//  There are 4 ways the width and height of the signature rectangle can be specified.
//  1) The width and height (in points) are both explicitly specified.
//     User space coordinates use "points" where 72 points equals 1 inch.
//     For example (3 inches wide and 1 inch high)
//     The fontScale is automatically chose to fit.  In addition, if a graphic (JPG or built-in SVG) is included,
//     it is automatically scaled such that the text + graphic fit together in the specified rectangle.
//     Note: When both height and width are explicitly specified, the resultant signature appearance rectangle
//     will match one of the dimensions, but the other dimension will be equal or smaller.  This is because the text
//     must be proportionally scaled.
json.UpdateInt("appearance.width",72 * 3);
json.UpdateInt("appearance.height",72);

//  The signature would have this appearance. In this case, the height is actually less than 1 inch because
//  if Chilkat chose a fontScale to fill the height, the resulting text's width would be too long for the desired width. 
//  (image:https://example-code.com/images/explicit_width_height.jpg/endImage)

//  2) The width is explicitly specified, but we use the keyword "auto" for height.
//     In this case, the fontScale is chosen to achieve the desired width,
//     and the height will be whatever the result of the chosen font scale.
//     In this example, the width is 4 inches, and the height is "auto".
json.UpdateInt("appearance.width",72 * 4);
json.UpdateString("appearance.height","auto");

//  The signature would have this appearance: 
//  (image:https://example-code.com/images/explicit_width_auto_height.jpg/endImage)

//  3) The height is explicitly specified, but we use the keyword "auto" for width.
//     In this case, the fontScale is chosen to achieve the desired height,
//     and the width will be whatever the result of the chosen font scale.
//     In this example, the height is 1 inch (72 points) and the width is "auto".
json.UpdateString("appearance.width","auto");
json.UpdateInt("appearance.height",72);

//  The signature would have this appearance.
//  (image:https://example-code.com/images/explicit_height_auto_width.jpg/endImage)

//  4) Finally, we don't need to specify width/height at all.  Instead, we can choose a fontScale
//     and the dimensions of the PDF signature appearance's rectangle will be the result of using the
//     specified fontScale.

Chilkat.JsonObject jAppearance = new Chilkat.JsonObject();
json.ObjectOf2("appearance",jAppearance);

jAppearance.Delete("width");
jAppearance.Delete("height");
json.UpdateString("appearance.fontScale","10.0");

//  With fontScale = "10.0"
//  (image:https://example-code.com/images/font_scale_10.jpg/endImage)

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

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

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

Debug.WriteLine("The PDF has been successfully cryptographically signed.");