Perl 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. Chilkat2 Perl

use strict;
use warnings;
use Chilkat2;

my $success = 0;

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

my $fmt = Chilkat2::Formats->new;
my $json = Chilkat2::JsonObject->new;
my $jsonOut = Chilkat2::JsonObject->new;
$json->UpdateString('payload.text', 'https://www.chilkatsoft.com/barcode_overview.asp');

# Encode the same text at each level.
my $levels = Chilkat2::JsonArray->new;
$levels->Load('["L","M","Q","H"]');
for my $i (0 .. 3) {
    $json->UpdateString('encoding.qr.errorCorrection', $levels->StringAt($i));
    $success = $fmt->QrCode('generate', $json, $jsonOut);
    if (!$success) {
        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.
my $json2 = Chilkat2::JsonObject->new;
$json2->UpdateString('payload.text', 'https://chilkatsoft.com');
$json2->UpdateString('encoding.qr.errorCorrection', 'L');
$success = $fmt->QrCode('generate', $json2, $jsonOut);
if (!$success) {
    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) {
    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