Image::PNG::QRCode - make a PNG image containing a QR code from text
use Image::PNG::QRCode 'qrpng'; qrpng (text => 'boom shake shake shake the room', out => 'shake.png');
This module converts input text to a PNG image of a QR code containing the text. The PNG image can either be stored to a file or it can be a scalar.
Image::PNG::Libpng requires "libpng" to be installed. "libpng" should already be installed on most Linux and Windows systems.
my $png = qrpng (text => 'this is my text');
This makes a scalar PNG data in $png containing the QR code PNG.
$png
qrpng (in => 'file.txt', out => 'file.png');
This makes a PNG file file.png from the contents of file.txt.
The function takes the following options.
qrpng (text => 'this is my text');
Text to convert to a QR code.
qrpng (in => 'file.txt');
in specifies an input 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.
in
text
out specifies an output file or a scalar to put the PNG data into.
out
qrpng (out => 'file.png');
writes to file.png, but
qrpng (out => \$s);
writes the PNG data into a scalar $s.
$s
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.
version
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.
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 4 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.
quiet
qrpng (in => 'in.txt', out => 'out.png', scale => 9);
scale is a positive integer which specifies how many pixels one "module" (one block of the QR code) occupies. The default is 3. You can't use fractional values. An arbitrary upper limit of 100 is imposed.
scale
This section is not completed.
This message is produced in the case of errors.
There is a script "qrpng" installed with the module:
qrpng "earphone pad"
makes qrcode.png. Try
qrpng --help
for more options.
There is an example script qrpng.cgi in examples which makes a PNG from a user's input.
QRCode.com from Denso Wave, the inventors of the QR code, contains much information.
Imager::QRCode is based on the Imager module and libqrencode.
Text::QRCode makes a text QR code. It's based on libqrencode.
HTML::QRCode is an HTML QR code system based on Text::QRCode.
Term::QRCode makes QR codes on terminal windows. It's based on Text::QRCode.
This is part of PostScript::Barcode. It's actually PostScript rather than Perl.
Image::QRCode::Effects is based on Imager::QRCode and adds "effects commonly used on QRCodes to make them look interesting".
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.
qrduino is a QR code generator developed for a platform called the Arduino by Tom Zerucha. Image::PNG::QRCode is a fork of this project.
libqrencode is the library underlying Text::QRCode and its dependents.
Google Charts offers a QR code generator. 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 is a Java project which can generate QR codes. These are one-bit monochrome ones.
QrCode.net is a .Net version.
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.
The QR code PNG files are very small and various tricks are used to make the memory use and the PNG file very small. Although the original plan was to interoperate with Image::PNG::Libpng, this ended up looking like a big burden to get only a small return, so this module actually just copies the parts of the code of Image::PNG::Libpng. If you want to manipulate the output PNG file you'll need to read it in again and operate on it.
The module isn't optimized for repeated uses, it builds up and tears down everything for each image.
The QR encoding is not checked for correctness. The QR code library comes from the "qrduino" project, but the contents have been worked on so it's not clear whether it's still correct. Also there was a bug in the original thing leading to reading uninitialized memory.
This encoder doesn't support the "shift-JIS" format. UTF-8 seems to pass through it OK. It doesn't use a BOM for the UTF-8.
The QR codes have only been checked by using two Android smartphones.
The QR code creation part (the contents of qrencode.c in the distribution) is copyright 2010, Tom Zerucha, https://github.com/tz1. The rest of the module is copyright by Ben Bullock 2015.
This Perl module is licensed under the Gnu General Public Licence version 3.
To install Image::PNG::QRCode, copy and paste the appropriate command in to your terminal.
cpanm
cpanm Image::PNG::QRCode
CPAN shell
perl -MCPAN -e shell install Image::PNG::QRCode
For more information on module installation, please visit the detailed CPAN module installation guide.