B4X

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.

B4X

Dim success As Boolean = False

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

Dim pdf As ChilkatPdf
pdf.Initialize("pdf")

'  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
    Log(pdf.LastErrorText)
    Return
End If


'  Options for signing are specified in JSON.
Dim json As ChilkatJsonObject
json.Initialize

'  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")

'  Use a font scale of 10.0
json.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.
json.UpdateString("appearance.text[0]", "Digitally signed by: cert_cn")
json.UpdateString("appearance.text[1]", "current_dt")
json.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

Dim jpgData As ChilkatBinData
jpgData.Initialize
success = jpgData.LoadFile("qa_data/jpg/university.jpg")
If success = False Then
    Log("Failed to load the JPG image.")
    Return
End If

success = pdf.SetSignatureJpeg(jpgData)
If success = False Then
    Log(pdf.LastErrorText)
    Return
End If


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

'  Load the signing certificate. (Use your own certificate.)
Dim cert As ChilkatCert
cert.Initialize("cert")
success = cert.LoadPfxFile("qa_data/pfx/myPdfSigningCert.pfx", "secret")
If success = False Then
    Log(cert.LastErrorText)
    Return
End If


'  Tell the pdf object to use the certificate for signing.
success = pdf.SetSigningCert(cert)
If success = False Then
    Log(pdf.LastErrorText)
    Return
End If


success = pdf.SignPdf(json, "qa_output/hello_signed.pdf")
If success = False Then
    Log(pdf.LastErrorText)
    Return
End If


Log("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)