Pascal (Lazarus/Delphi)

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. 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;
  jAppearance: TJsonObject;
  cert: TCert;

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);

  //  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.

  jAppearance := TJsonObject.Create;
  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.)
  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.');


  pdf.Free;
  json.Free;
  jAppearance.Free;
  cert.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.