VB.NET Requires Chilkat v11.7.0+

Choose Which PDF Optimizations to Apply

See more PDF Optimization Examples

Demonstrates turning individual optimizations off. Every option is on by default except the two reserved ones; setting one to false leaves that part of the file alone. Here the old revisions are kept (so the output is an incremental update that leaves the original bytes untouched) and the fonts are not subset, which is what a workflow that will later fill in form fields or replace text needs. The "actions" in the report name only the options that did something. 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 pdf As New Chilkat.Pdf
success = pdf.LoadFile("qa_data/pdf/grand_canyon_hiking_guide.pdf")
If (success = False) Then
    Debug.WriteLine(pdf.LastErrorText)
    Exit Sub
End If


Dim json As New Chilkat.JsonObject

'  The options, all boolean, all true by default:
'    compressUncompressed    compress streams stored with no filter
'    recompressFlate         deflate again at the chosen level
'    replaceLegacyFilters    re-encode LZW, RunLength, ASCIIHex and ASCII85 streams as Flate
'    imagePredictors         apply a PNG predictor where it makes an image stream smaller
'    dedupeStreams           merge streams whose contents are identical
'    dedupeObjects           merge objects whose contents are identical
'    removeUnreferenced      drop objects nothing refers to
'    removeUnusedResources   drop resource entries no page uses
'    removeUnusedLayers      drop optional-content groups nothing uses
'    coalesceContent         join a page's content streams into one
'    tidyContent             remove redundant operators and white space from page content
'    subsetFonts             keep only the glyphs the document uses
'    dropOldRevisions        drop superseded revisions (a full rewrite)
'  
'  mergeFontSubsets and compactType1Fonts are reserved for a later release and are reported in
'  "skipped" when requested.  See the "Why an Optimization Was Skipped" example.

json.UpdateBool("subsetFonts",False)
json.UpdateBool("dropOldRevisions",False)

Dim jsonOut As New Chilkat.JsonObject
success = pdf.Optimize("optimize",json,jsonOut)
If (success = False) Then
    Debug.WriteLine(pdf.LastErrorText)
    Exit Sub
End If


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


Debug.WriteLine("bytesSaved: " & jsonOut.IntOf("bytesSaved"))

'  Only the options that actually did something appear under "actions", each with the number of
'  objects it affected and the bytes it saved.
Dim actions As New Chilkat.JsonObject
success = jsonOut.ObjectOf2("actions",actions)
If (success = False) Then
    Debug.WriteLine(jsonOut.LastErrorText)
    Exit Sub
End If


Dim oneAction As New Chilkat.JsonObject
Dim i As Integer = 0
Dim numActions As Integer = actions.Size
While i < numActions
    Dim actionName As String = actions.NameAt(i)
    success = actions.ObjectOf2(actionName,oneAction)
    If (success = False) Then
        Debug.WriteLine(actions.LastErrorText)
        Exit Sub
    End If

    Debug.WriteLine(actionName & ": " & oneAction.IntOf("bytesSaved") & " bytes, " & oneAction.IntOf("count") & " objects")
    i = i + 1
End While