The pyqrcode module is a QR code generator that is simple to use and written in pure python. The module can automates most of the building process for creating QR codes. Most codes can be created using only two lines of code!
Unlike other generators, all of the helpers can be controlled manually. You are free to set any or all of the properties of your QR code.
QR codes can be saved as SVG, PNG (by using the pypng module), or plain text. They can also be displayed directly in most Linux terminal emulators. PIL is not used to render the image files.
The pyqrcode module attempts to follow the QR code standard as closely as possible. The terminology and the encodings used in pyqrcode come directly from the standard. This module also follows the algorithm laid out in the standard.
The pyqrcode module only requires Python 2.6, Python 2.7 or Python 3. You may want to install pypng in order to render PNG files, but it is optional.
Installation is simple. It can be installed from pip using the following command:
$ pip install pyqrcode
or from the code
$ python setup.py install
This is the only import you need. The heart of the module is the QRCode class. You can construct the class normally, or use the create wrapper function.
>>> import pyqrcode
This module supports three encodings for data: numeric, alphanumeric, and binary. The numeric type is the most efficient way to encode digits. As the name implies it is designed to encode integers. Some numbers might be two large, the object can use a string containing only digits instead of an actual number.
>>> number = pyqrcode.create(123456789012345)
The alphanumeric type is very limited in that it can only encode some ASCII
characters. It encodes: uppercase letters, 0-9, the horizontal space, and eight
punctuation characters. A complete list of the possible characters that
can be encoded can be found in the pyqrcode.tables.ascii_codes dictionary. The
available characters will let you encode a URL (note that you have to transform
the characters to upper-case otherwise the
create function will use the
binary encoding automatically).
>>> url = pyqrcode.create('http://uca.edu'.upper())
When all else fails the data can be encoded in pure binary. The quotation below must be encoded in binary because of the lower-cased characters, the apostrophe and the new line character.
>>> life = pyqrcode.create('''MR. CREOSOTE: Better get a bucket. I'm going to throw up. MAITRE D: Uh, Gaston! A bucket for monsieur. There you are, monsieur.''')
There two other encodings that are unimplemented. The first is used for Kanji characters. This encoding is unimplemented at this time because I don't speak Japanese. If anyone wants to help me write an encoder for Kanji, shoot me an email. The other is ECI mode which allows for multiple encodings in one QR code (this will be implemented in a future version).
Manually Setting The QR Code's Properties
There are many situation where you might wish to have more fine grained control over how the QR Code is generated. You can specify all the properties of your QR code through the create function. There are three main properties to a QR code.
The error parameter sets the error correction level of the code. Each level has an associated name given by a letter: L, M, Q, or H; each level can correct up to 7, 15, 25, or 30 percent of the data respectively. There are several ways to specify the level, see pyqrcode.tables.modes for all the possible values. By default this parameter is set to 'H' which is the highest possible error correction, but it has the smallest available data capacity.
The version parameter specifies the size and data capacity of the code. Versions are any integer between 1 and 40, where version 1 is the smallest QR code, and version 40 is the largest. By default, the object uses the data's encoding and error correction level to calculate the smallest possible version. You may want to specify this parameter for consistency when generating several QR codes with varying amounts of data. That way all of the generated codes would have the same size.
Finally, the mode parameter sets how the contents will be encoded. As mentioned above, three of the five possible encodings have been written. By default the object uses the most efficient encoding for the contents. You can change this though. See qrcode.tables.modes for a list of possible values for this parameter.
The code below constructs a QR code with 25% error correction, size 27, and forces the encoding to be binary (rather than numeric).
>>> big_code = pyqrcode.create('0987654321', error='L', version=27, mode='binary')
There are four possible formats for rendering the QR Code. The first is to render it as a string of 1's and 0's. This is method is used to help end users create their own renderer. It is also possible to print the code such that it is directly displayable in most Linux terminals. There are also two image based renderers. Both allow you to set the colors used. They also take a scaling factor, that way each module is not rendered as 1 pixel.
The terminal renderer outputs a string of ASCII escape codes that when displayed in a compatible terminal, will display a valid QR code. The background and module colors are settable (although as with any time you display colors in the terminal, there are several caveats).
>>> print(url.terminal()) >>> print(url.terminal('red', 'white'))
The SVG renderer outputs the QR Code as a scalable vector graphic. This renderer does not require any external modules. Instead it hand draws the QR code as a set paths.
>>> url.svg(sys.stdout, scale=1) >>> url.svg('uca.svg', scale=4, module_color="#7D007D")
Alternatively, if you install the pypng module, you can render the QR Code to a PNG file. Colors should be specified as RGB or RGBA if you want to take advantage of transparency.
>>> number.png('big-number.png') >>> life.png('sketch.png', scale=6, module_color=(0, 0, 0, 128), background=(0xff, 0xff, 0xcc))
Finally, there is a text based renderer. This will output the QR code as a string of 1's and 0's, with each row of the code on a new line.