Visual FoxPro

PDF Sign Unsigned Signature Field

See more PDF Signatures Examples

Demonstrates how to sign a PDF's unsigned signature field.

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

Visual FoxPro

LOCAL lnSuccess
LOCAL loPdf
LOCAL loJson
LOCAL loCert

lnSuccess = 0

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

loPdf = CreateObject('Chilkat.Pdf')

*  Load a PDF containing an unsigned signature field.
lnSuccess = loPdf.LoadFile("qa_data/pdf/unsigned_sig_field/due_diligence.pdf")
IF (lnSuccess = 0) THEN
    ? loPdf.LastErrorText
    RELEASE loPdf
    CANCEL
ENDIF

*  A PDF with an unsigned signature field appears in Adobe Acrobat as shown below.
*  (When the mouse pointer is hovered over the field, a tooltip will likely show a message
*  such as "Unsigned signature field (Click to sign)".  
*  This example code will automatically find the unsigned signature field,
*  and signs using your certificate.  It automatically sizes the text to the space alotted
*  for the signature.
*  (image:https://example-code.com/images/unsignedSigField.jpg/endImage)

*  Options for signing are specified in JSON.
loJson = CreateObject('Chilkat.JsonObject')

*  In most cases, the signingCertificateV2 and signingTime attributes are required.
loJson.UpdateInt("signingCertificateV2",1)
loJson.UpdateInt("signingTime",1)

*  We don't specify the page or a specific location because Chilkat will automatically
*  find the unsigned signature field and use its location and size and will scale the
*  signatures visual appearance (text + graphics) to the correct size required to fit.
*  We only need to indicate the desire to fill the unsigned signature field.
loJson.UpdateBool("appearance.fillUnsignedSignatureField",1)

*  Starting in Chilkat v9.5.0.90, if a PDF contains multiple unsigned signature fields,
*  the field to be signed can be chosen by name:
*  To list unsigned signature fields, see this example: List PDF Unsigned Signature Fields
loJson.UpdateString("unsignedSignatureField","doctor_signature")

*  Note: If the PDF document contains multiple unsigned signature fields, Chilkat will 
*  sign the 1st one found. 

*  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.
loJson.UpdateString("appearance.text[0]","Digitally signed by: cert_cn")
loJson.UpdateString("appearance.text[1]","current_dt")
loJson.UpdateString("appearance.text[2]","The crazy brown fox jumps over the lazy dog.")

*  This signature will include one of the built-in SVG graphics (green-check-grey-circle).
loJson.UpdateString("appearance.image","green-check-grey-circle")
loJson.UpdateString("appearance.imagePlacement","left")

*  Load the signing certificate. (Use your own certificate.)
loCert = CreateObject('Chilkat.Cert')
lnSuccess = loCert.LoadPfxFile("qa_data/pfx/myPdfSigningCert.pfx","secret")
IF (lnSuccess = 0) THEN
    ? loCert.LastErrorText
    RELEASE loPdf
    RELEASE loJson
    RELEASE loCert
    CANCEL
ENDIF

*  Tell the pdf object to use the certificate for signing.
lnSuccess = loPdf.SetSigningCert(loCert)
IF (lnSuccess = 0) THEN
    ? loPdf.LastErrorText
    RELEASE loPdf
    RELEASE loJson
    RELEASE loCert
    CANCEL
ENDIF

lnSuccess = loPdf.SignPdf(loJson,"qa_output/due_diligence_signed.pdf")
IF (lnSuccess = 0) THEN
    ? loPdf.LastErrorText
    RELEASE loPdf
    RELEASE loJson
    RELEASE loCert
    CANCEL
ENDIF

? "The PDF has been successfully cryptographically signed."

*  The appearance of the signature appears in Adobe Acrobat as shown below.
*  (image:https://example-code.com/images/signature3.jpg/endImage)

RELEASE loPdf
RELEASE loJson
RELEASE loCert