qrpng

    my $png = qrpng (text => 'this is my text');

This makes a scalar $png containing the QR code PNG data.

    qrpng (in => 'file.txt', out => 'file.png');

This makes a PNG file file.png from the contents of file.txt.

qrpng options

This function takes the following options.

text

    qrpng (text => 'this is my text');
    

The text you want to convert to a QR code.

in

    qrpng (in => 'file.txt');
    

Specify a file of text to convert to a QR code.

If you specify both "text" and "in", the module prints a warning message and uses the contents of "in", overwriting the value of "text".

out

Specify an output file to put the PNG data into. With a scalar argument,

     qrpng (out => 'file.png');
    

writes to file.png, but with a scalar reference,

     qrpng (out => \$s);
    

writes the PNG data into the scalar $s.

version

    qrpng (in => 'in.txt', out => 'out.png', version => 40);
    

"version" specifies the "version" of the QR code. The "version" is the "size" of the barcode, which controls the amount of information it can contain. The maximum value of "version" is 40.

If no version is specified, the program chooses one using the length of the text. If you choose a version which is too small for the input data, a fatal error occurs. Usually it isn't necessary to set this parameter.

level

    qrpng (in => 'in.txt', out => 'out.png', level => 4);
    

Specify the amount of error checking code (ECC) to use. The default is level one, which corresponds to 7% error tolerance. The level can go up to 4, which corresponds to 30% error tolerance. Values less than one or greater than four cause a fatal error.

quiet

    qrpng (in => 'in.txt', out => 'out.png', quiet => 9);
    

"quiet" is a non-negative integer which specifies the size of the "quiet zone", the white area around the QR code, in units of "modules", the size of one black square of the QR code. The default is four modules. The QR specification requires a minimum of a four-module quiet zone, but you could set this to zero if, for example, you are going to embed the image in a white background, so it's not an error to set this lower. There is an arbitrary upper limit of 100 imposed.

Note that changing this size makes little difference to the output PNG's size because it's just a white area which is compressed to take little room.

scale

    qrpng (in => 'in.txt', out => 'out.png', scale => 9);
    

"scale" is a positive integer which specifies how many pixels one "module" (one square block of the QR code) occupies. The default is 3. You can't use fractional values. An arbitrary upper limit of 100 is imposed.

size

    qrpng (text => 'lime green', size => \$size);
    

Get the size (height and width in pixels) of the output PNG. This requires a scalar reference.

qrpng-data.pl

This example makes a data URL QR code:

    use Image::PNG::QRCode 'qrpng';
    use URI;
    my $data = 'abcdefghijklmnopqrstuvwxyz';
    my $u = URI->new ('data:');
    $u->media_type ('image/png');
    $u->data (qrpng (text => $data));
    print "<img src='$u'>\n";

(This example is included as qrpng-data.pl <https://fastapi.metacpan.org/source/BKB/Image-PNG-QRCode-0.11/examples/qrpng-data.pl> in the distribution.)

qrpng CGI script

This example CGI (common gateway interface) script makes a PNG from a user's input.

    use Image::PNG::QRCode 'qrpng';
    use URI::Escape;
    
    my $request = $ENV{QUERY_STRING};
    if ($request) {
        my %params;
        my @params = split /\&/, $request;
        for my $param (@params) {
            my ($k, $v) = split /=/, $param;
            if ($k && $v) {
                $v =~ s/\+/ /g;
                $params{$k} = uri_unescape ($v);
            }
        }
        if ($params{w}) {
            send_qr_code (%params);
        }
    }
    print <<EOF;
    Content-Type: text/plain
    Status: 400
    
    You didn't send anything, use me like this: qrpng.cgi?w=message-to-encode
    EOF
    exit;
    
    sub send_qr_code
    {
        my (%params) = @_;
        my $w = $params{w};
        my $s;
        eval {
            qrpng (text => $w, out => \$s);
        };
        if ($@) {
            print <<EOF;
    Content-Type: text/plain
    Status: 500
    
    qrpng failed like this: $@
    EOF
            exit;
        }
        binmode STDOUT, ":raw";
        my $l = length $s;
        print <<EOF;
    Content-Type: image/png
    Content-Length: $l
    
    $s
    EOF
        exit;
    }

(This example is included as qrpng.pl <https://fastapi.metacpan.org/source/BKB/Image-PNG-QRCode-0.11/examples/qrpng.pl> in the distribution.)

About QR codes

QRCode.com from Denso Wave <http://www.qrcode.com/en/index.html>, the inventors of the QR code, contains much information.

Other QR code generators

On CPAN

Imager::QRCode

Imager::QRCode is based on the Imager module and "libqrencode".

Text::QRCode

Text::QRCode makes a text QR code. It's based on "libqrencode".

HTML::QRCode

HTML::QRCode is an HTML QR code system based on Text::QRCode.

Term::QRCode

Term::QRCode makes QR codes on terminal windows. It's based on Text::QRCode.

PostScript::Barcode::qrcode

This is part of PostScript::Barcode. It's actually PostScript rather than Perl.

Image::QRCode::Effects

Image::QRCode::Effects is based on Imager::QRCode and adds "effects commonly used on QRCodes to make them look interesting".

GD::Barcode::QRcode

GD::Barcode::QRcode is a Pure-Perl implementation of QR codes using the GD library for the graphical part. At the time of writing, the last update was in 2004.

Vector::QRCode::EPS

Vector::QRCode::EPS is a generator that returns a QRCode data as PostScript::Simple object.

Non-CPAN

qrduino

qrduino <https://github.com/tz1/qrduino> is a QR code generator developed by Tom Zerucha for a microcomputer platform called the Arduino. Image::PNG::QRCode is a fork of this project.

libqrencode

libqrencode <http://fukuchi.org/works/qrencode/index.html.en> is the library underlying Text::QRCode and its dependents.

Google Charts QR code generator

Google Charts offers a QR code generator <https://developers.google.com/chart/infographics/docs/qr_codes>. The QR codes generated by Image::PNG::QRCode are about 1/3 the size of the default Google charts ones, for example the "Hello world" example in the above documentation is 728 bytes, but Image::PNG::QRCode makes an equivalent QR code using only 243 bytes. The reason for the reduced size is that Google Charts uses RGB colour space, whereas Image::PNG::QRCode uses one-bit monochrome colour space.

ZXing

ZXing <https://github.com/zxing/zxing/> is a Java project which can generate QR codes. These are one-bit monochrome ones.

QrCode.net

QrCode.net <http://qrcodenet.codeplex.com/> is a .Net version.

JavaScript qrcode generators

These might be a useful alternative to using a server-side solution:

<http://d-project.googlecode.com/svn/trunk/misc/qrcode/js/>

<http://code.google.com/p/jsqrencode/downloads/list>

However, sending these large JavaScript files over the internet will use much more bandwidth than sending the QR codes themselves, for most usage cases.

Project Nayuki QR Code generator library

Project Nayuki QR Code generator library <https://www.nayuki.io/page/qr-code-generator-library> contains an online JavaScript QR code generator and links to implementations in C, C++, Java, JavaScript, Python, and Rust.