Pascal (Lazarus/Delphi)

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.

Pascal (Lazarus/Delphi)

program ChilkatDemo;

// Demonstrates using the Chilkat Pascal wrapper via the C bridge DLL.
// Builds as a console application under Lazarus (FPC) or Delphi.

{$IFDEF FPC}
  {$MODE DELPHI}
{$ENDIF}
{$APPTYPE CONSOLE}

uses
  {$IFDEF UNIX}
  cthreads,
  {$ENDIF}
  SysUtils,
  CkDllLoader,
  Chilkat.Pdf,
  Chilkat.Cert,
  Chilkat.JsonObject;

// ---------------------------------------------------------------------------

procedure RunDemo;
var
  success: Boolean;
  pdf: TPdf;
  json: TJsonObject;
  cert: TCert;
  pdf2: TPdf;

begin
  success := False;

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

  pdf := TPdf.Create;

  //  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) then
    begin
      WriteLn(pdf.LastErrorText);
      Exit;
    end;

  //  Options for signing are specified in JSON.
  json := TJsonObject.Create;

  //  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.)
  cert := TCert.Create;
  success := cert.LoadPfxFile('qa_data/pfx/myPdfSigningCert.pfx','pfx_password');
  if (success = False) then
    begin
      WriteLn(cert.LastErrorText);
      Exit;
    end;

  //  Tell the pdf object to use the certificate for signing.
  success := pdf.SetSigningCert(cert);
  if (success = False) then
    begin
      WriteLn(pdf.LastErrorText);
      Exit;
    end;

  success := pdf.SignPdf(json,'qa_output/hello_signed.pdf');
  if (success = False) then
    begin
      WriteLn(pdf.LastErrorText);
      Exit;
    end;

  WriteLn('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');

  pdf2 := TPdf.Create;
  success := pdf2.LoadFile('qa_output/hello_signed.pdf');
  success := pdf2.SetSigningCert(cert);

  success := pdf2.SignPdf(json,'qa_output/hello_signed2.pdf');
  if (success = False) then
    begin
      WriteLn(pdf2.LastErrorText);
      Exit;
    end;

  WriteLn('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)


  pdf.Free;
  json.Free;
  cert.Free;
  pdf2.Free;

end;

// ---------------------------------------------------------------------------

begin

  try
    RunDemo;
  except
    on E: Exception do
      WriteLn('Unhandled exception: ', E.ClassName, ': ', E.Message);
  end;

  WriteLn;
  {$IFDEF MSWINDOWS}
  WriteLn('Press Enter to exit...');
  ReadLn;
  {$ENDIF}
end.