PHP ActiveX Requires Chilkat v11.7.0+

QR Code Error Correction Levels

See more QR Code Examples

Demonstrates the four QR error-correction levels. L, M, Q and H allow a reader to recover the data when about 7%, 15%, 25% and 30% of the symbol is damaged or covered. More error correction leaves less room for data, so the same text needs a larger symbol at a higher level. The default is M. The example also shows boostErrorCorrection, which raises the level for free when the chosen version has room to spare. PHP ActiveX

<?php

$success = 0;

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

$fmt = new COM("Chilkat.Formats");
$json = new COM("Chilkat.JsonObject");
$jsonOut = new COM("Chilkat.JsonObject");
$json->UpdateString('payload.text','https://www.chilkatsoft.com/barcode_overview.asp');

//  Encode the same text at each level.
$levels = new COM("Chilkat.JsonArray");
$levels->Load('[\'L\',\'M\',\'Q\',\'H\']');

for ($i = 0; $i <= 3; $i++) {
    $json->UpdateString('encoding.qr.errorCorrection',$levels->stringAt($i));
    $success = $fmt->QrCode('generate',$json,$jsonOut);
    if ($success == 0) {
        print $fmt->LastErrorText . "\n";
        exit;
    }

    print 'level ' . $levels->stringAt($i) . ': version ' . $jsonOut->IntOf('symbols[0].selectedEncoding.version') . ', ' . $jsonOut->IntOf('symbols[0].dimensions.modulesWide')
         . ' modules wide' . "\n";
}

//  The four symbols.  They hold the same text, and the higher the level, the larger the symbol:

//  

//  A symbol often has room left over.  boostErrorCorrection uses it: the level is raised
//  as far as the same version allows, so the symbol is no larger but is more robust.
$json2 = new COM("Chilkat.JsonObject");
$json2->UpdateString('payload.text','https://chilkatsoft.com');
$json2->UpdateString('encoding.qr.errorCorrection','L');
$success = $fmt->QrCode('generate',$json2,$jsonOut);
if ($success == 0) {
    print $fmt->LastErrorText . "\n";
    exit;
}

print 'level L requested: version ' . $jsonOut->IntOf('symbols[0].selectedEncoding.version') . ', level ' . $jsonOut->stringOf('symbols[0].selectedEncoding.errorCorrection') . "\n";

$json2->UpdateBool('encoding.qr.boostErrorCorrection',1);
$success = $fmt->QrCode('generate',$json2,$jsonOut);
if ($success == 0) {
    print $fmt->LastErrorText . "\n";
    exit;
}

print 'level L with boost: version ' . $jsonOut->IntOf('symbols[0].selectedEncoding.version') . ', level ' . $jsonOut->stringOf('symbols[0].selectedEncoding.errorCorrection') . "\n";

//  Level L, and level M reached by the boost.  The two symbols are the same size:

//  

//  Sample output:

//  level L: version 3, 29 modules wide
//  level M: version 4, 33 modules wide
//  level Q: version 5, 37 modules wide
//  level H: version 6, 41 modules wide
//  level L requested: version 2, level L
//  level L with boost: version 2, level M

?>