(VB.NET) 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.

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

Chilkat .NET Downloads Chilkat .NET Framework Chilkat for .NET Core

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

Dim pdf As New Chilkat.Pdf

' Load a PDF to be signed.
' The "hello.pdf" is available at https://chilkatsoft.com/hello.pdf
Dim success As Boolean = pdf.LoadFile("qa_data/pdf/hello.pdf")
If (success = False) Then
    Debug.WriteLine(pdf.LastErrorText)
    Exit Sub
End If



' Options for signing are specified in JSON.
Dim json As New Chilkat.JsonObject

' 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")

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

' Add a built-in SVG graphic to the right.
json.UpdateString("appearance.image","blue-check-mark")
json.UpdateString("appearance.imagePlacement","right")
json.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.
json.UpdateInt("appearance.width",72 * 3)
json.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. 


' 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".
json.UpdateInt("appearance.width",72 * 4)
json.UpdateString("appearance.height","auto")

' The signature would have this appearance: 


' 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".
json.UpdateString("appearance.width","auto")
json.UpdateInt("appearance.height",72)

' The signature would have this appearance.


' 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.

Dim jAppearance As Chilkat.JsonObject = json.ObjectOf("appearance")
jAppearance.Delete("width")
jAppearance.Delete("height")

json.UpdateString("appearance.fontScale","10.0")

' With fontScale = "10.0"



' Load the signing certificate. (Use your own certificate.)
Dim cert As New Chilkat.Cert
success = cert.LoadPfxFile("qa_data/pfx/myPdfSigningCert.pfx","pfx_password")
If (success = False) Then
    Debug.WriteLine(cert.LastErrorText)
    Exit Sub
End If


' Tell the pdf object to use the certificate for signing.
success = pdf.SetSigningCert(cert)
If (success = False) Then
    Debug.WriteLine(pdf.LastErrorText)
    Exit Sub
End If


success = pdf.SignPdf(json,"qa_output/hello_signed.pdf")
If (success = False) Then
    Debug.WriteLine(pdf.LastErrorText)
    Exit Sub
End If


Debug.WriteLine("The PDF has been successfully cryptographically signed.")