(PHP Extension) Decompress Large Binary File in Blocks

Decompresses a large binary file in blocks.

Note: This example requires Chilkat v11.0.0 or greater.

Chilkat PHP Downloads PHP Extension for Windows, Linux, MacOS, Alpine Linux

<?php

include("chilkat.php");

$success = false;

// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

$facSrc = new CkFileAccess();
$facDest = new CkFileAccess();

// Open a previously compressed file for decompressing.
// See Compress Large File in Blocks

$success = $facSrc->OpenForRead('c:/temp/qa_output/compressedBmp.dat');
if ($success == false) {
    print $facSrc->lastErrorText() . "\n";
    exit;
}

// If we compress in 32K chunks, find out how many blocks there will be.
$blockSize = 32768;
$numBlocks = $facSrc->GetNumBlocks($blockSize);

// Open an output file for the decompressed data.
$success = $facDest->OpenForWrite('c:/temp/qa_output/decompressed.bmp');
if ($success == false) {
    print $facDest->lastErrorText() . "\n";
    exit;
}

$compress = new CkCompression();
$compress->put_Algorithm('deflate');

$decompressedBytes = new CkByteData();
$compressedBytes = new CkByteData();

// Assuming numBlocks > 1
$compress->put_FirstChunk(true);
$compress->put_LastChunk(false);

$i = 0;
while ($i < $numBlocks) {
    $success = $facSrc->ReadBlock($i,$blockSize,$compressedBytes);

    $success = $compress->DecompressBytes($compressedBytes,$decompressedBytes);
    $facDest->FileWrite($decompressedBytes);

    $i = $i + 1;

    $compress->put_FirstChunk(false);
    if ($i == ($numBlocks - 1)) {
        $compress->put_LastChunk(true);
    }

}

$facSrc->FileClose();
$facDest->FileClose();

print 'Finished decompressing file.' . "\n";

?>