Ruby 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 A PDF that has been edited and saved several times carries every earlier revision: the superseded objects are still in the file, reachable through the older cross-reference sections.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. Ruby

require 'chilkat'

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 grand_canyon_hiking_guide.pdf

pdf = Chilkat::CkPdf.new()
success = pdf.LoadFile("qa_data/pdf/grand_canyon_hiking_guide.pdf")
if (success == false)
    print pdf.lastErrorText() + "\n";
    exit
end

#  How much of this file is superseded revisions?
json = Chilkat::CkJsonObject.new()
jsonOut = Chilkat::CkJsonObject.new()
success = pdf.Optimize("audit",json,jsonOut)
if (success == false)
    print pdf.lastErrorText() + "\n";
    exit
end

print "fileSize:     " + jsonOut.IntOf("fileSize").to_s() + "\n";
print "oldRevisions: " + jsonOut.IntOf("usage.oldRevisions.bytes").to_s() + "\n";

#  Drop them, and nothing else, so that the saving is attributable.
json.UpdateBool("compressUncompressed",false)
json.UpdateBool("recompressFlate",false)
json.UpdateBool("replaceLegacyFilters",false)
json.UpdateBool("imagePredictors",false)
json.UpdateBool("dedupeStreams",false)
json.UpdateBool("dedupeObjects",false)
json.UpdateBool("removeUnreferenced",false)
json.UpdateBool("removeUnusedResources",false)
json.UpdateBool("removeUnusedLayers",false)
json.UpdateBool("coalesceContent",false)
json.UpdateBool("tidyContent",false)
json.UpdateBool("subsetFonts",false)
json.UpdateBool("dropOldRevisions",true)

success = pdf.Optimize("optimize",json,jsonOut)
if (success == false)
    print pdf.lastErrorText() + "\n";
    exit
end

success = pdf.WriteFile("qa_output/grand_canyon_one_revision.pdf")
if (success == false)
    print pdf.lastErrorText() + "\n";
    exit
end

#  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.
fac = Chilkat::CkFileAccess.new()
print "bytesSaved (reported): " + jsonOut.IntOf("bytesSaved").to_s() + "\n";
print "written file:          " + fac.FileSize("qa_output/grand_canyon_one_revision.pdf").to_s() + "\n";