PureBasic
PureBasic
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.
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IncludeFile "CkCert.pb"
IncludeFile "CkJsonObject.pb"
IncludeFile "CkPdf.pb"
Procedure ChilkatExample()
success.i = 0
; This example requires the Chilkat API to have been previously unlocked.
; See Global Unlock Sample for sample code.
pdf.i = CkPdf::ckCreate()
If pdf.i = 0
Debug "Failed to create object."
ProcedureReturn
EndIf
; Load a PDF to be signed.
; The "hello.pdf" is available at https://chilkatsoft.com/hello.pdf
success = CkPdf::ckLoadFile(pdf,"qa_data/pdf/hello.pdf")
If success = 0
Debug CkPdf::ckLastErrorText(pdf)
CkPdf::ckDispose(pdf)
ProcedureReturn
EndIf
; Options for signing are specified in JSON.
json.i = CkJsonObject::ckCreate()
If json.i = 0
Debug "Failed to create object."
ProcedureReturn
EndIf
; In most cases, the signingCertificateV2 and signingTime attributes are required.
CkJsonObject::ckUpdateInt(json,"signingCertificateV2",1)
CkJsonObject::ckUpdateInt(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::ckUpdateInt(json,"page",CkPdf::ckNumPages(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::ckUpdateString(json,"appearance.y","bottom")
CkJsonObject::ckUpdateString(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::ckUpdateString(json,"appearance.fontScale","9.0")
CkJsonObject::ckUpdateString(json,"appearance.text[0]","Digitally signed by: cert_cn")
CkJsonObject::ckUpdateString(json,"appearance.text[1]","current_dt")
CkJsonObject::ckUpdateString(json,"appearance.image","document-accepted")
CkJsonObject::ckUpdateString(json,"appearance.imagePlacement","left")
CkJsonObject::ckUpdateString(json,"appearance.imageOpacity","100")
; Load the signing certificate. (Use your own certificate.)
cert.i = CkCert::ckCreate()
If cert.i = 0
Debug "Failed to create object."
ProcedureReturn
EndIf
success = CkCert::ckLoadPfxFile(cert,"qa_data/pfx/myPdfSigningCert.pfx","pfx_password")
If success = 0
Debug CkCert::ckLastErrorText(cert)
CkPdf::ckDispose(pdf)
CkJsonObject::ckDispose(json)
CkCert::ckDispose(cert)
ProcedureReturn
EndIf
; Tell the pdf object to use the certificate for signing.
success = CkPdf::ckSetSigningCert(pdf,cert)
If success = 0
Debug CkPdf::ckLastErrorText(pdf)
CkPdf::ckDispose(pdf)
CkJsonObject::ckDispose(json)
CkCert::ckDispose(cert)
ProcedureReturn
EndIf
success = CkPdf::ckSignPdf(pdf,json,"qa_output/hello_signed.pdf")
If success = 0
Debug CkPdf::ckLastErrorText(pdf)
CkPdf::ckDispose(pdf)
CkJsonObject::ckDispose(json)
CkCert::ckDispose(cert)
ProcedureReturn
EndIf
Debug "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::ckUpdateString(json,"appearance.y","792")
CkJsonObject::ckUpdateString(json,"appearance.x","0")
CkJsonObject::ckUpdateString(json,"appearance.text[0]","Digitally signed again by: cert_cn")
CkJsonObject::ckUpdateString(json,"appearance.text[1]","current_dt")
CkJsonObject::ckUpdateString(json,"appearance.image","document-accepted")
CkJsonObject::ckUpdateString(json,"appearance.imagePlacement","right")
pdf2.i = CkPdf::ckCreate()
If pdf2.i = 0
Debug "Failed to create object."
ProcedureReturn
EndIf
success = CkPdf::ckLoadFile(pdf2,"qa_output/hello_signed.pdf")
success = CkPdf::ckSetSigningCert(pdf2,cert)
success = CkPdf::ckSignPdf(pdf2,json,"qa_output/hello_signed2.pdf")
If success = 0
Debug CkPdf::ckLastErrorText(pdf2)
CkPdf::ckDispose(pdf)
CkJsonObject::ckDispose(json)
CkCert::ckDispose(cert)
CkPdf::ckDispose(pdf2)
ProcedureReturn
EndIf
Debug "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::ckDispose(pdf)
CkJsonObject::ckDispose(json)
CkCert::ckDispose(cert)
CkPdf::ckDispose(pdf2)
ProcedureReturn
EndProcedure