Xojo Plugin Requires Chilkat v11.7.0+

Remove PDF Objects Nothing Refers To

See more PDF Optimization Examples

Demonstrates removeUnreferenced. When a page, an image or a whole section is replaced in an editor, the objects it used often stay in the file with nothing pointing at them any more. They are not old revisions -- they are in the current revision, simply unreachable -- so only a reachability walk from the document catalog finds them. In a publication assembled over several editing passes this is frequently the largest single saving. Xojo Plugin

Dim success As Boolean
success = 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 watersense_accomplishments.pdf

Dim pdf As New Chilkat.Pdf
success = pdf.LoadFile("qa_data/pdf/watersense_accomplishments.pdf")
If (success = False) Then
    System.DebugLog(pdf.LastErrorText)
    Return
End If

Dim json As New Chilkat.JsonObject
Dim jsonOut As New Chilkat.JsonObject
success = pdf.Optimize("audit",json,jsonOut)
If (success = False) Then
    System.DebugLog(pdf.LastErrorText)
    Return
End If

System.DebugLog("fileSize: " + Str(jsonOut.IntOf("fileSize")))
System.DebugLog("removeUnreferenced would save: " + Str(jsonOut.IntOf("estimatedSavings.removeUnreferenced")))

//  Optimize with the defaults and see how many objects were actually dropped.
success = pdf.Optimize("optimize",json,jsonOut)
If (success = False) Then
    System.DebugLog(pdf.LastErrorText)
    Return
End If

success = pdf.WriteFile("qa_output/watersense_optimized.pdf")
If (success = False) Then
    System.DebugLog(pdf.LastErrorText)
    Return
End If

System.DebugLog("objects removed: " + Str(jsonOut.IntOf("actions.removeUnreferenced.count")))
System.DebugLog("bytes saved:     " + Str(jsonOut.IntOf("actions.removeUnreferenced.bytesSaved")))

//  Nothing a page needs is ever removed: the walk starts at the document catalog and follows every
//  reference, including the ones in annotations, the structure tree, named destinations and the
//  optional-content configuration.
System.DebugLog("pages after: " + Str(pdf.NumPages))