CkPython 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. CkPython

import sys
import 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 watersense_accomplishments.pdf

pdf = chilkat.CkPdf()
success = pdf.LoadFile("qa_data/pdf/watersense_accomplishments.pdf")
if (success == False):
    print(pdf.lastErrorText())
    sys.exit()

json = chilkat.CkJsonObject()
jsonOut = chilkat.CkJsonObject()
success = pdf.Optimize("audit",json,jsonOut)
if (success == False):
    print(pdf.lastErrorText())
    sys.exit()

print("fileSize: " + str(jsonOut.IntOf("fileSize")))
print("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):
    print(pdf.lastErrorText())
    sys.exit()

success = pdf.WriteFile("qa_output/watersense_optimized.pdf")
if (success == False):
    print(pdf.lastErrorText())
    sys.exit()

print("objects removed: " + str(jsonOut.IntOf("actions.removeUnreferenced.count")))
print("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.
print("pages after: " + str(pdf.get_NumPages()))