VB.NET Requires Chilkat v11.7.0+

How a PDF Watermark Is Stored: artifact, annotation, layer or content

See more PDF Watermark Examples

Demonstrates the approach member, which decides how the watermark is stored and therefore what can be done with it afterwards. artifact (the default) is marked content that viewers draw, text extraction leaves out and Chilkat can remove later. annotation is a Watermark annotation, always on top, and the only approach allowed on a signed PDF while PreserveSignatures is true. layer is an optional-content layer the viewer can hide and that can be made print-only. content draws straight into the page with no marker: visible everywhere and the tamper-resistant choice, but by design it can never be listed or removed again. VB.NET

Dim success As Boolean = False

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

'  The PDF used in this example is available at two_page_memo.pdf

Dim json As New Chilkat.JsonObject
Dim jsonOut As New Chilkat.JsonObject
Dim filter As New Chilkat.JsonObject

'  The same watermark stored four different ways, each in its own copy of the document.
Dim pdf As New Chilkat.Pdf
success = pdf.LoadFile("qa_data/pdf/two_page_memo.pdf")
If (success = False) Then
    Debug.WriteLine(pdf.LastErrorText)
    Exit Sub
End If


json.UpdateString("type","text")
json.UpdateString("text","DRAFT")
json.UpdateString("id","draft")
json.UpdateString("approach","artifact")
success = pdf.Watermark("add",json,jsonOut)
If (success = False) Then
    Debug.WriteLine(pdf.LastErrorText)
    Exit Sub
End If


'  detect answers whether anything matching the filter is in the document.  Finding nothing is
'  still success: "found" is simply false.
filter.UpdateString("id","draft")
success = pdf.Watermark("detect",filter,jsonOut)
If (success = False) Then
    Debug.WriteLine(pdf.LastErrorText)
    Exit Sub
End If

Debug.WriteLine("artifact: found = " & jsonOut.BoolOf("found"))

'  An annotation: always drawn on top, and the one approach a signed PDF accepts.
Dim pdf2 As New Chilkat.Pdf
success = pdf2.LoadFile("qa_data/pdf/two_page_memo.pdf")
If (success = False) Then
    Debug.WriteLine(pdf2.LastErrorText)
    Exit Sub
End If

json.UpdateString("approach","annotation")
success = pdf2.Watermark("add",json,jsonOut)
If (success = False) Then
    Debug.WriteLine(pdf2.LastErrorText)
    Exit Sub
End If

success = pdf2.Watermark("detect",filter,jsonOut)
If (success = False) Then
    Debug.WriteLine(pdf2.LastErrorText)
    Exit Sub
End If

Debug.WriteLine("annotation: found = " & jsonOut.BoolOf("found"))

'  A layer, which the viewer's layers panel can switch off.
Dim pdf3 As New Chilkat.Pdf
success = pdf3.LoadFile("qa_data/pdf/two_page_memo.pdf")
If (success = False) Then
    Debug.WriteLine(pdf3.LastErrorText)
    Exit Sub
End If

json.UpdateString("approach","layer")
json.UpdateString("layer.name","Draft marking")
success = pdf3.Watermark("add",json,jsonOut)
If (success = False) Then
    Debug.WriteLine(pdf3.LastErrorText)
    Exit Sub
End If

success = pdf3.Watermark("detect",filter,jsonOut)
If (success = False) Then
    Debug.WriteLine(pdf3.LastErrorText)
    Exit Sub
End If

Debug.WriteLine("layer: found = " & jsonOut.BoolOf("found"))

'  Drawn into the page content with no marker.  There is nothing to find afterwards, which is the
'  point of it: it cannot be stripped out by a tool that removes watermarks.
Dim pdf4 As New Chilkat.Pdf
success = pdf4.LoadFile("qa_data/pdf/two_page_memo.pdf")
If (success = False) Then
    Debug.WriteLine(pdf4.LastErrorText)
    Exit Sub
End If

json.UpdateString("approach","content")
success = pdf4.Watermark("add",json,jsonOut)
If (success = False) Then
    Debug.WriteLine(pdf4.LastErrorText)
    Exit Sub
End If

success = pdf4.Watermark("detect",filter,jsonOut)
If (success = False) Then
    Debug.WriteLine(pdf4.LastErrorText)
    Exit Sub
End If

Debug.WriteLine("content: found = " & jsonOut.BoolOf("found"))

'  Sample output:

'  artifact: found = True
'  annotation: found = True
'  layer: found = True
'  content: found = False