Delphi DLL

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.

Delphi DLL

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

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
pdf: HCkPdf;
json: HCkJsonObject;
cert: HCkCert;
pdf2: HCkPdf;

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);

// 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.
CkJsonObject_UpdateInt(json,'page',CkPdf_getNumPages(pdf));

// 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.
CkJsonObject_UpdateString(json,'appearance.y','bottom');
CkJsonObject_UpdateString(json,'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.
CkJsonObject_UpdateString(json,'appearance.fontScale','9.0');

CkJsonObject_UpdateString(json,'appearance.text[0]','Digitally signed by: cert_cn');
CkJsonObject_UpdateString(json,'appearance.text[1]','current_dt');
CkJsonObject_UpdateString(json,'appearance.image','document-accepted');
CkJsonObject_UpdateString(json,'appearance.imagePlacement','left');
CkJsonObject_UpdateString(json,'appearance.imageOpacity','100');

// Load the signing certificate. (Use your own certificate.)
cert := CkCert_Create();
success := CkCert_LoadPfxFile(cert,'qa_data/pfx/myPdfSigningCert.pfx','pfx_password');
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 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:

CkJsonObject_UpdateString(json,'appearance.y','792');
CkJsonObject_UpdateString(json,'appearance.x','0');

CkJsonObject_UpdateString(json,'appearance.text[0]','Digitally signed again by: cert_cn');
CkJsonObject_UpdateString(json,'appearance.text[1]','current_dt');
CkJsonObject_UpdateString(json,'appearance.image','document-accepted');
CkJsonObject_UpdateString(json,'appearance.imagePlacement','right');

pdf2 := CkPdf_Create();
success := CkPdf_LoadFile(pdf2,'qa_output/hello_signed.pdf');
success := CkPdf_SetSigningCert(pdf2,cert);

success := CkPdf_SignPdf(pdf2,json,'qa_output/hello_signed2.pdf');
if (success = False) then
  begin
    Memo1.Lines.Add(CkPdf__lastErrorText(pdf2));
    Exit;
  end;

Memo1.Lines.Add('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)

CkPdf_Dispose(pdf);
CkJsonObject_Dispose(json);
CkCert_Dispose(cert);
CkPdf_Dispose(pdf2);

end;