Visual FoxPro

PDF Signature with Background Image (Seal/Stamp/etc.)

See more PDF Signatures Examples

Demonstrates how to sign a PDF with an appearance that includes a background image, such as a seal, stamp, etc.

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

Visual FoxPro

LOCAL lnSuccess
LOCAL loPdf
LOCAL loJson
LOCAL loJpgData
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 to be signed.
*  The "hello.pdf" is available at https://chilkatsoft.com/hello.pdf
lnSuccess = loPdf.LoadFile("qa_data/pdf/hello.pdf")
IF (lnSuccess = 0) THEN
    ? loPdf.LastErrorText
    RELEASE loPdf
    CANCEL
ENDIF

*  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)

*  Put the signature on page 1, top left
loJson.UpdateInt("page",1)
loJson.UpdateString("appearance.y","top")
loJson.UpdateString("appearance.x","left")

*  Use a font scale of 10.0
loJson.UpdateString("appearance.fontScale","10.0")

*  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.")

*  Load a JPG image to be shown with 30% opacity in the background.
*  (the image must be in the JPG format)
*  The sample university.jpb is available at https://example-code.com/images/university.jpg

loJpgData = CreateObject('Chilkat.BinData')
lnSuccess = loJpgData.LoadFile("qa_data/jpg/university.jpg")
IF (lnSuccess = 0) THEN
    ? "Failed to load the JPG image."
    RELEASE loPdf
    RELEASE loJson
    RELEASE loJpgData
    CANCEL
ENDIF

lnSuccess = loPdf.SetSignatureJpeg(loJpgData)
IF (lnSuccess = 0) THEN
    ? loPdf.LastErrorText
    RELEASE loPdf
    RELEASE loJson
    RELEASE loJpgData
    CANCEL
ENDIF

*  Specify that we want to display the JPG image in the center with 30% opacity.
loJson.UpdateString("appearance.image","custom-jpg")
loJson.UpdateString("appearance.imagePlacement","center")
loJson.UpdateString("appearance.imageOpacity","30")

*  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 loJpgData
    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 loJpgData
    RELEASE loCert
    CANCEL
ENDIF

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

? "The PDF has been successfully cryptographically signed."

*  The appearance of the signature appears in Adobe Acrobat as shown below.
*  The JPG is automatically scaled to the size of the signature based on the signature's font scale
*  and number of text lines.
*  (image:https://example-code.com/images/signature2.jpg/endImage)

RELEASE loPdf
RELEASE loJson
RELEASE loJpgData
RELEASE loCert