PHP 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 PHP

<?php

use Chilkat2\JsonObject;
use Chilkat2\Pdf;

// 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 = new Pdf();
try {
    $pdf->LoadFile('qa_data/pdf/watersense_accomplishments.pdf');

    $json = new JsonObject();
    $jsonOut = new JsonObject();
    $pdf->Optimize('audit', $json, $jsonOut);
} catch (\Chilkat2\Exception $e) {
    echo $e->getMessage(), "\n";
    exit;
}

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

// Optimize with the defaults and see how many objects were actually dropped.
try {
    $pdf->Optimize('optimize', $json, $jsonOut);

    $pdf->WriteFile('qa_output/watersense_optimized.pdf');
} catch (\Chilkat2\Exception $e) {
    echo $e->getMessage(), "\n";
    exit;
}

echo 'objects removed: ', $jsonOut->IntOf('actions.removeUnreferenced.count'), "\n";
echo '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.
echo 'pages after: ', $pdf->NumPages, "\n";