Perl 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. Chilkat2 Perl

use strict;
use warnings;
use Chilkat2;

# 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

my $pdf = Chilkat2::Pdf->new;
my $success = $pdf->LoadFile('qa_data/pdf/watersense_accomplishments.pdf');
if (!$success) {
    print $pdf->LastErrorText, "\n";
    exit;
}

my $json = Chilkat2::JsonObject->new;
my $jsonOut = Chilkat2::JsonObject->new;
$success = $pdf->Optimize('audit', $json, $jsonOut);
if (!$success) {
    print $pdf->LastErrorText, "\n";
    exit;
}

print 'fileSize: ', $jsonOut->IntOf('fileSize'), "\n";
print 'removeUnreferenced would save: ', $jsonOut->IntOf('estimatedSavings.removeUnreferenced'), "\n";

# Optimize with the defaults and see how many objects were actually dropped.
$success = $pdf->Optimize('optimize', $json, $jsonOut);
if (!$success) {
    print $pdf->LastErrorText, "\n";
    exit;
}

$success = $pdf->WriteFile('qa_output/watersense_optimized.pdf');
if (!$success) {
    print $pdf->LastErrorText, "\n";
    exit;
}

print 'objects removed: ', $jsonOut->IntOf('actions.removeUnreferenced.count'), "\n";
print 'bytes saved:     ', $jsonOut->IntOf('actions.removeUnreferenced.bytesSaved'), "\n";

# 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: ', $pdf->NumPages, "\n";