Xbase++

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.

Xbase++

LOCAL nSuccess
LOCAL oPdf
LOCAL oJson
LOCAL oCert
LOCAL oPdf2

nSuccess := 0

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

oPdf := CreateObject("Chilkat.Pdf")

//  Load a PDF to be signed.
//  The "hello.pdf" is available at https://chilkatsoft.com/hello.pdf
nSuccess := oPdf:LoadFile("qa_data/pdf/hello.pdf")
IF (nSuccess == 0)
    ? oPdf:LastErrorText
    oPdf:destroy()
    RETURN
ENDIF

//  Options for signing are specified in JSON.
oJson := CreateObject("Chilkat.JsonObject")

//  In most cases, the signingCertificateV2 and signingTime attributes are required.
oJson:UpdateInt("signingCertificateV2", 1)
oJson: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.
oJson:UpdateInt("page", oPdf: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.
oJson:UpdateString("appearance.y", "bottom")
oJson: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.
oJson:UpdateString("appearance.fontScale", "9.0")

oJson:UpdateString("appearance.text[0]", "Digitally signed by: cert_cn")
oJson:UpdateString("appearance.text[1]", "current_dt")
oJson:UpdateString("appearance.image", "document-accepted")
oJson:UpdateString("appearance.imagePlacement", "left")
oJson:UpdateString("appearance.imageOpacity", "100")

//  Load the signing certificate. (Use your own certificate.)
oCert := CreateObject("Chilkat.Cert")
nSuccess := oCert:LoadPfxFile("qa_data/pfx/myPdfSigningCert.pfx", "pfx_password")
IF (nSuccess == 0)
    ? oCert:LastErrorText
    oPdf:destroy()
    oJson:destroy()
    oCert:destroy()
    RETURN
ENDIF

//  Tell the pdf object to use the certificate for signing.
nSuccess := oPdf:SetSigningCert(oCert)
IF (nSuccess == 0)
    ? oPdf:LastErrorText
    oPdf:destroy()
    oJson:destroy()
    oCert:destroy()
    RETURN
ENDIF

nSuccess := oPdf:SignPdf(oJson, "qa_output/hello_signed.pdf")
IF (nSuccess == 0)
    ? oPdf:LastErrorText
    oPdf:destroy()
    oJson:destroy()
    oCert:destroy()
    RETURN
ENDIF

? "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:

oJson:UpdateString("appearance.y", "792")
oJson:UpdateString("appearance.x", "0")

oJson:UpdateString("appearance.text[0]", "Digitally signed again by: cert_cn")
oJson:UpdateString("appearance.text[1]", "current_dt")
oJson:UpdateString("appearance.image", "document-accepted")
oJson:UpdateString("appearance.imagePlacement", "right")

oPdf2 := CreateObject("Chilkat.Pdf")
nSuccess := oPdf2:LoadFile("qa_output/hello_signed.pdf")
nSuccess := oPdf2:SetSigningCert(oCert)

nSuccess := oPdf2:SignPdf(oJson, "qa_output/hello_signed2.pdf")
IF (nSuccess == 0)
    ? oPdf2:LastErrorText
    oPdf:destroy()
    oJson:destroy()
    oCert:destroy()
    oPdf2:destroy()
    RETURN
ENDIF

? "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)

oPdf:destroy()
oJson:destroy()
oCert:destroy()
oPdf2:destroy()