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 A PDF that has been edited and saved several times carries every earlier revision: the superseded objects are still in the file, reachable through the older cross-reference sections.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

<?php

include("chilkat.php");

$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 = new CkPdf();
$success = $pdf->LoadFile('qa_data/pdf/grand_canyon_hiking_guide.pdf');
if ($success == false) {
    print $pdf->lastErrorText() . "\n";
    exit;
}

//  How much of this file is superseded revisions?
$json = new CkJsonObject();
$jsonOut = new CkJsonObject();
$success = $pdf->Optimize('audit',$json,$jsonOut);
if ($success == false) {
    print $pdf->lastErrorText() . "\n";
    exit;
}

print 'fileSize:     ' . $jsonOut->IntOf('fileSize') . "\n";
print 'oldRevisions: ' . $jsonOut->IntOf('usage.oldRevisions.bytes') . "\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;
}

$success = $pdf->WriteFile('qa_output/grand_canyon_one_revision.pdf');
if ($success == false) {
    print $pdf->lastErrorText() . "\n";
    exit;
}

//  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 = new CkFileAccess();
print 'bytesSaved (reported): ' . $jsonOut->IntOf('bytesSaved') . "\n";
print 'written file:          ' . $fac->FileSize('qa_output/grand_canyon_one_revision.pdf') . "\n";

?>