PowerBuilder Requires Chilkat v11.7.0+

Remove a PDF's Old Revisions

See more PDF Optimization Examples

Demonstrates dropOldRevisions. A PDF that has been edited and saved several times carries every earlier revision: the superseded objects are still in the file, reachable through the older cross-reference sections. The audit reports them as "oldRevisions", and dropping them is often the single largest saving in a real document. Dropping them requires a full rewrite, which is why it invalidates existing digital signatures. PowerBuilder

integer li_rc
long li_Success
oleobject loo_Pdf
oleobject loo_Json
oleobject loo_JsonOut
oleobject loo_Fac

li_Success = 0

//  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

loo_Pdf = create oleobject
li_rc = loo_Pdf.ConnectToNewObject("Chilkat.Pdf")
if li_rc < 0 then
    destroy loo_Pdf
    MessageBox("Error","Connecting to COM object failed")
    return
end if
li_Success = loo_Pdf.LoadFile("qa_data/pdf/grand_canyon_hiking_guide.pdf")
if li_Success = 0 then
    Write-Debug loo_Pdf.LastErrorText
    destroy loo_Pdf
    return
end if

//  How much of this file is superseded revisions?
loo_Json = create oleobject
li_rc = loo_Json.ConnectToNewObject("Chilkat.JsonObject")

loo_JsonOut = create oleobject
li_rc = loo_JsonOut.ConnectToNewObject("Chilkat.JsonObject")

li_Success = loo_Pdf.Optimize("audit",loo_Json,loo_JsonOut)
if li_Success = 0 then
    Write-Debug loo_Pdf.LastErrorText
    destroy loo_Pdf
    destroy loo_Json
    destroy loo_JsonOut
    return
end if

Write-Debug "fileSize:     " + string(loo_JsonOut.IntOf("fileSize"))
Write-Debug "oldRevisions: " + string(loo_JsonOut.IntOf("usage.oldRevisions.bytes"))

//  Drop them, and nothing else, so that the saving is attributable.
loo_Json.UpdateBool("compressUncompressed",0)
loo_Json.UpdateBool("recompressFlate",0)
loo_Json.UpdateBool("replaceLegacyFilters",0)
loo_Json.UpdateBool("imagePredictors",0)
loo_Json.UpdateBool("dedupeStreams",0)
loo_Json.UpdateBool("dedupeObjects",0)
loo_Json.UpdateBool("removeUnreferenced",0)
loo_Json.UpdateBool("removeUnusedResources",0)
loo_Json.UpdateBool("removeUnusedLayers",0)
loo_Json.UpdateBool("coalesceContent",0)
loo_Json.UpdateBool("tidyContent",0)
loo_Json.UpdateBool("subsetFonts",0)
loo_Json.UpdateBool("dropOldRevisions",1)

li_Success = loo_Pdf.Optimize("optimize",loo_Json,loo_JsonOut)
if li_Success = 0 then
    Write-Debug loo_Pdf.LastErrorText
    destroy loo_Pdf
    destroy loo_Json
    destroy loo_JsonOut
    return
end if

li_Success = loo_Pdf.WriteFile("qa_output/grand_canyon_one_revision.pdf")
if li_Success = 0 then
    Write-Debug loo_Pdf.LastErrorText
    destroy loo_Pdf
    destroy loo_Json
    destroy loo_JsonOut
    return
end if

//  The saving is an estimate: what the old revisions occupied is known exactly, but the writer
//  decides the final layout.  Measure the written file for the real number.
loo_Fac = create oleobject
li_rc = loo_Fac.ConnectToNewObject("Chilkat.FileAccess")

Write-Debug "bytesSaved (reported): " + string(loo_JsonOut.IntOf("bytesSaved"))
Write-Debug "written file:          " + string(loo_Fac.FileSize("qa_output/grand_canyon_one_revision.pdf"))


destroy loo_Pdf
destroy loo_Json
destroy loo_JsonOut
destroy loo_Fac