Xbase++ Requires Chilkat v11.0.0+

PDF Signature Appearance Width and Height

See more PDF Signatures Examples

This example explains how the width and height of the signature appearance rectangle box is determined. Xbase++

LOCAL nSuccess
LOCAL oPdf
LOCAL oJson
LOCAL oJAppearance
LOCAL oCert

nSuccess := 0

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

oPdf := CreateObject("Chilkat.Pdf")

//  Load a PDF to be signed.
//  The "hello.pdf" is available at https://chilkatsoft.com/hello.pdf
nSuccess := oPdf:LoadFile("qa_data/pdf/hello.pdf")
IF (nSuccess == 0)
    ? oPdf:LastErrorText
    oPdf:destroy()
    RETURN
ENDIF

//  Options for signing are specified in JSON.
oJson := CreateObject("Chilkat.JsonObject")

//  In most cases, the signingCertificateV2 and signingTime attributes are required.
oJson:UpdateInt("signingCertificateV2", 1)
oJson:UpdateInt("signingTime", 1)

//  Put the signature on page 1, top left
oJson:UpdateInt("page", 1)
oJson:UpdateString("appearance.y", "top")
oJson:UpdateString("appearance.x", "left")

//  Add some text.
oJson:UpdateString("appearance.text[0]", "Digitally signed by: cert_cn")
oJson:UpdateString("appearance.text[1]", "current_dt")

//  Add a built-in SVG graphic to the right.
oJson:UpdateString("appearance.image", "blue-check-mark")
oJson:UpdateString("appearance.imagePlacement", "right")
oJson:UpdateString("appearance.imageOpacity", "100")

//  There are 4 ways the width and height of the signature rectangle can be specified.
//  1) The width and height (in points) are both explicitly specified.
//     User space coordinates use "points" where 72 points equals 1 inch.
//     For example (3 inches wide and 1 inch high)
//     The fontScale is automatically chose to fit.  In addition, if a graphic (JPG or built-in SVG) is included,
//     it is automatically scaled such that the text + graphic fit together in the specified rectangle.
//     Note: When both height and width are explicitly specified, the resultant signature appearance rectangle
//     will match one of the dimensions, but the other dimension will be equal or smaller.  This is because the text
//     must be proportionally scaled.
oJson:UpdateInt("appearance.width", 72 * 3)
oJson:UpdateInt("appearance.height", 72)

//  The signature would have this appearance. In this case, the height is actually less than 1 inch because
//  if Chilkat chose a fontScale to fill the height, the resulting text's width would be too long for the desired width. 
//  (image:https://example-code.com/images/explicit_width_height.jpg/endImage)

//  2) The width is explicitly specified, but we use the keyword "auto" for height.
//     In this case, the fontScale is chosen to achieve the desired width,
//     and the height will be whatever the result of the chosen font scale.
//     In this example, the width is 4 inches, and the height is "auto".
oJson:UpdateInt("appearance.width", 72 * 4)
oJson:UpdateString("appearance.height", "auto")

//  The signature would have this appearance: 
//  (image:https://example-code.com/images/explicit_width_auto_height.jpg/endImage)

//  3) The height is explicitly specified, but we use the keyword "auto" for width.
//     In this case, the fontScale is chosen to achieve the desired height,
//     and the width will be whatever the result of the chosen font scale.
//     In this example, the height is 1 inch (72 points) and the width is "auto".
oJson:UpdateString("appearance.width", "auto")
oJson:UpdateInt("appearance.height", 72)

//  The signature would have this appearance.
//  (image:https://example-code.com/images/explicit_height_auto_width.jpg/endImage)

//  4) Finally, we don't need to specify width/height at all.  Instead, we can choose a fontScale
//     and the dimensions of the PDF signature appearance's rectangle will be the result of using the
//     specified fontScale.

oJAppearance := CreateObject("Chilkat.JsonObject")
oJson:ObjectOf2("appearance", oJAppearance)

oJAppearance:Delete("width")
oJAppearance:Delete("height")
oJson:UpdateString("appearance.fontScale", "10.0")

//  With fontScale = "10.0"
//  (image:https://example-code.com/images/font_scale_10.jpg/endImage)

//  Load the signing certificate. (Use your own certificate.)
oCert := CreateObject("Chilkat.Cert")
nSuccess := oCert:LoadPfxFile("qa_data/pfx/myPdfSigningCert.pfx", "pfx_password")
IF (nSuccess == 0)
    ? oCert:LastErrorText
    oPdf:destroy()
    oJson:destroy()
    oJAppearance:destroy()
    oCert:destroy()
    RETURN
ENDIF

//  Tell the pdf object to use the certificate for signing.
nSuccess := oPdf:SetSigningCert(oCert)
IF (nSuccess == 0)
    ? oPdf:LastErrorText
    oPdf:destroy()
    oJson:destroy()
    oJAppearance:destroy()
    oCert:destroy()
    RETURN
ENDIF

nSuccess := oPdf:SignPdf(oJson, "qa_output/hello_signed.pdf")
IF (nSuccess == 0)
    ? oPdf:LastErrorText
    oPdf:destroy()
    oJson:destroy()
    oJAppearance:destroy()
    oCert:destroy()
    RETURN
ENDIF

? "The PDF has been successfully cryptographically signed."

oPdf:destroy()
oJson:destroy()
oJAppearance:destroy()
oCert:destroy()