Delphi DLL

PDF Signature with Background Image (Seal/Stamp/etc.)

See more PDF Signatures Examples

Demonstrates how to sign a PDF with an appearance that includes a background image, such as a seal, stamp, etc.

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

Delphi DLL

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, BinData, Pdf, Cert, JsonObject;

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
pdf: HCkPdf;
json: HCkJsonObject;
jpgData: HCkBinData;
cert: HCkCert;

begin
success := False;

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

pdf := CkPdf_Create();

// Load a PDF to be signed.
// The "hello.pdf" is available at https://chilkatsoft.com/hello.pdf
success := CkPdf_LoadFile(pdf,'qa_data/pdf/hello.pdf');
if (success = False) then
  begin
    Memo1.Lines.Add(CkPdf__lastErrorText(pdf));
    Exit;
  end;

// Options for signing are specified in JSON.
json := CkJsonObject_Create();

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

// Put the signature on page 1, top left
CkJsonObject_UpdateInt(json,'page',1);
CkJsonObject_UpdateString(json,'appearance.y','top');
CkJsonObject_UpdateString(json,'appearance.x','left');

// Use a font scale of 10.0
CkJsonObject_UpdateString(json,'appearance.fontScale','10.0');

// In this example, the appearance of the digital signature will contain three lines:
// 1) The signing certificate's common name
// 2) The current date/time
// 3) Some arbitrary text.
// The keyword "cert_cn" is replaced with the Certificate's Subject Common Name.
// The keyword "current_dt" is replaced with the current date/time.
// Any number of appearance text lines can be added.
CkJsonObject_UpdateString(json,'appearance.text[0]','Digitally signed by: cert_cn');
CkJsonObject_UpdateString(json,'appearance.text[1]','current_dt');
CkJsonObject_UpdateString(json,'appearance.text[2]','The crazy brown fox jumps over the lazy dog.');

// Load a JPG image to be shown with 30% opacity in the background.
// (the image must be in the JPG format)
// The sample university.jpb is available at https://example-code.com/images/university.jpg

jpgData := CkBinData_Create();
success := CkBinData_LoadFile(jpgData,'qa_data/jpg/university.jpg');
if (success = False) then
  begin
    Memo1.Lines.Add('Failed to load the JPG image.');
    Exit;
  end;
success := CkPdf_SetSignatureJpeg(pdf,jpgData);
if (success = False) then
  begin
    Memo1.Lines.Add(CkPdf__lastErrorText(pdf));
    Exit;
  end;

// Specify that we want to display the JPG image in the center with 30% opacity.
CkJsonObject_UpdateString(json,'appearance.image','custom-jpg');
CkJsonObject_UpdateString(json,'appearance.imagePlacement','center');
CkJsonObject_UpdateString(json,'appearance.imageOpacity','30');

// Load the signing certificate. (Use your own certificate.)
cert := CkCert_Create();
success := CkCert_LoadPfxFile(cert,'qa_data/pfx/myPdfSigningCert.pfx','secret');
if (success = False) then
  begin
    Memo1.Lines.Add(CkCert__lastErrorText(cert));
    Exit;
  end;

// Tell the pdf object to use the certificate for signing.
success := CkPdf_SetSigningCert(pdf,cert);
if (success = False) then
  begin
    Memo1.Lines.Add(CkPdf__lastErrorText(pdf));
    Exit;
  end;

success := CkPdf_SignPdf(pdf,json,'qa_output/hello_signed.pdf');
if (success = False) then
  begin
    Memo1.Lines.Add(CkPdf__lastErrorText(pdf));
    Exit;
  end;

Memo1.Lines.Add('The PDF has been successfully cryptographically signed.');

// The appearance of the signature appears in Adobe Acrobat as shown below.
// The JPG is automatically scaled to the size of the signature based on the signature's font scale
// and number of text lines.
// (image:https://example-code.com/images/signature2.jpg/endImage)

CkPdf_Dispose(pdf);
CkJsonObject_Dispose(json);
CkBinData_Dispose(jpgData);
CkCert_Dispose(cert);

end;