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Visual FoxPro

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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LOCAL lnSuccess
LOCAL loPdf
LOCAL loJson
LOCAL loCert
LOCAL loPdf2

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)

* 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.
loJson.UpdateInt("page",loPdf.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.
loJson.UpdateString("appearance.y","bottom")
loJson.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.
loJson.UpdateString("appearance.fontScale","9.0")

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

* Load the signing certificate. (Use your own certificate.)
loCert = CreateObject('Chilkat.Cert')
lnSuccess = loCert.LoadPfxFile("qa_data/pfx/myPdfSigningCert.pfx","pfx_password")
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/hello_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 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:

loJson.UpdateString("appearance.y","792")
loJson.UpdateString("appearance.x","0")

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

loPdf2 = CreateObject('Chilkat.Pdf')
lnSuccess = loPdf2.LoadFile("qa_output/hello_signed.pdf")
lnSuccess = loPdf2.SetSigningCert(loCert)

lnSuccess = loPdf2.SignPdf(loJson,"qa_output/hello_signed2.pdf")
IF (lnSuccess = 0) THEN
    ? loPdf2.LastErrorText
    RELEASE loPdf
    RELEASE loJson
    RELEASE loCert
    RELEASE loPdf2
    CANCEL
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)

RELEASE loPdf
RELEASE loJson
RELEASE loCert
RELEASE loPdf2