VB.NET Requires Chilkat v11.7.0+

PDF Object Streams: generate, preserve or disable

See more PDF Optimization Examples

Demonstrates the objectStreams option. An object stream packs many small objects (dictionaries, not stream data) into one compressed stream, which is usually a worthwhile saving in a document with many pages or tags. "generate" (the default) packs them and writes a cross-reference stream; "preserve" keeps the file as it is -- packed if it already was, not packed if it was not; "disable" writes every object on its own with a classic cross-reference table, which is what a PDF 1.4 reader needs. Object streams require PDF 1.5 and are skipped for PDF/A-1. 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 grand_canyon_hiking_guide.pdf

Dim fac As New Chilkat.FileAccess
Dim json As New Chilkat.JsonObject
Dim jsonOut As New Chilkat.JsonObject

'  generate: pack the objects (the default).
Dim pdf1 As New Chilkat.Pdf
success = pdf1.LoadFile("qa_data/pdf/grand_canyon_hiking_guide.pdf")
If (success = False) Then
    Debug.WriteLine(pdf1.LastErrorText)
    Exit Sub
End If

json.UpdateString("objectStreams","generate")
success = pdf1.Optimize("optimize",json,jsonOut)
If (success = False) Then
    Debug.WriteLine(pdf1.LastErrorText)
    Exit Sub
End If

success = pdf1.WriteFile("qa_output/grand_canyon_objstm_generate.pdf")
If (success = False) Then
    Debug.WriteLine(pdf1.LastErrorText)
    Exit Sub
End If

Debug.WriteLine("generate: " & fac.FileSize("qa_output/grand_canyon_objstm_generate.pdf") & " bytes, objects packed: " & jsonOut.IntOf("actions.objectStreams.count"))

'  disable: every object on its own, with a classic cross-reference table.
Dim pdf2 As New Chilkat.Pdf
success = pdf2.LoadFile("qa_data/pdf/grand_canyon_hiking_guide.pdf")
If (success = False) Then
    Debug.WriteLine(pdf2.LastErrorText)
    Exit Sub
End If

json.UpdateString("objectStreams","disable")
success = pdf2.Optimize("optimize",json,jsonOut)
If (success = False) Then
    Debug.WriteLine(pdf2.LastErrorText)
    Exit Sub
End If

success = pdf2.WriteFile("qa_output/grand_canyon_objstm_disable.pdf")
If (success = False) Then
    Debug.WriteLine(pdf2.LastErrorText)
    Exit Sub
End If

Debug.WriteLine("disable:  " & fac.FileSize("qa_output/grand_canyon_objstm_disable.pdf") & " bytes")

'  preserve: leave the file's own structure alone.  Use it when the output must stay readable by
'  whatever reads the input today.
Dim pdf3 As New Chilkat.Pdf
success = pdf3.LoadFile("qa_data/pdf/grand_canyon_hiking_guide.pdf")
If (success = False) Then
    Debug.WriteLine(pdf3.LastErrorText)
    Exit Sub
End If

json.UpdateString("objectStreams","preserve")
success = pdf3.Optimize("optimize",json,jsonOut)
If (success = False) Then
    Debug.WriteLine(pdf3.LastErrorText)
    Exit Sub
End If

success = pdf3.WriteFile("qa_output/grand_canyon_objstm_preserve.pdf")
If (success = False) Then
    Debug.WriteLine(pdf3.LastErrorText)
    Exit Sub
End If

Debug.WriteLine("preserve: " & fac.FileSize("qa_output/grand_canyon_objstm_preserve.pdf") & " bytes")