PHP ActiveX

Decompress Large Binary File in Blocks

See more Compression Examples

Decompresses a large binary file in blocks. PHP ActiveX

<?php

$success = 0;

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

$facSrc = new COM("Chilkat.FileAccess");
$facDest = new COM("Chilkat.FileAccess");

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

$success = $facSrc->OpenForRead('c:/temp/qa_output/compressedBmp.dat');
if ($success == 0) {
    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 == 0) {
    print $facDest->LastErrorText . "\n";
    exit;
}

$compress = new COM("Chilkat.Compression");
$compress->Algorithm = 'deflate';

// Assuming numBlocks > 1
$compress->FirstChunk = 1;
$compress->LastChunk = 0;

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

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

    $i = $i + 1;

    $compress->FirstChunk = 0;
    if ($i == ($numBlocks - 1)) {
        $compress->LastChunk = 1;
    }

}

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

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

?>