Reading and Generating QR codes in Python using QRtools

This article aims to introduce the use of the python library: qrtools. This library can be used to both read QR codes and generate them.

What are QR codes?

QR code, or quick response code, is a trademark for a type of 2 dimensional barcode. 2 dimensional barcodes are similar to one dimensional barcodes, but can store more information per unit area.

Installation and Dependencies

Debian Linux: qrtools can be installed on debian based linux systems with the following commands
```
sudo apt-get update
sudo apt-get install python-qrtools
```
The following dependencies must be installed as well
```
[sudo] pip install pypng
[sudo] pip install zbar
[sudo] pip install pillow
```
Windows: qrtools can be installed on windows by downloading the file from here. On downloading and extraction, run the following command from inside the folder
```
python setup.py install
```

Generate a QR Code

qrtools contains a class QR (can be viewed in the source code), for which we must initially create an object. The object takes the following arguments

data
pixel_size
level
margin_size
data_type

To create a QR code with default settings, we must simply specify the data while creating the object. Note that the data must be a unicode object if non-ASCII objects are going to be used.

# Python 2.x program to generate QR code 
from qrtools 
import QR 
  
# creates the QR object 
my_QR = QR(data = u"Example") 
  
# encodes to a QR code 
my_QR.encode() 

If the program runs successfully, it returns a value of 0, and the QR code is stored in the tmp folder. To know the exact location, use the following command

print my_QR.filename

Sample output

/tmp/qr-1496334996.385343/7489ebbcc2a00056ddaaaac190bce473e5c03696ea1bd8ed83cf59a174283862.png

This file can now be moved to another folder as per our convenience

# Python 2.x program to generate QR code 
from qrtools import QR 
  
import os 
my_QR = QR(data = u"Example") 
my_QR.encode() 
  
# command to move the QR code to the desktop 
os.system("sudo mv " + my_QR.filename + " ~/Desktop") 

The pixel value of the QR code may also be changed by specifying the value during the creation of the QR object. The default size tends to be a little small for reading using scanners on smartphones, so a size of around 10 would be ideal for such purposes, for example:

my_QR = QR(data = u"example", pixel_size = 10)

The below QR code has pixel size = 10, and has been encoded with a URL

We can also add email data, sms data, mms data, bookmarks, etc to the QR code. The following code excerpt is taken from the source code, which specifies the various datatypes that can be used along with the format of the data that would be required for its usage:

# use these for custom data formats eg. url, phone number, VCARD 
# data should be an unicode object or a list of unicode objects 
data_encode = { 
    'text': lambda data: data, 
    'url': encode_url, 
    'email': lambda data: 'mailto:' + re.compile( 
        r'^mailto:', re.IGNORECASE 
    ).sub('', data), 
    'emailmessage': lambda data: 'MATMSG:TO:' + data[0] + ';SUB:' + data[1] + 
                           ';BODY:' + data[2] + ';;', 
    'telephone': lambda data: 'tel:' + re.compile( 
        r'^tel:', re.IGNORECASE 
    ).sub('', data), 
    'sms': lambda data: 'SMSTO:' + data[0] + ':' + data[1], 
    'mms': lambda data: 'MMSTO:' + data[0] + ':' + data[1], 
    'geo': lambda data: 'geo:' + data[0] + ', ' + data[1], 
    'bookmark': lambda data: "MEBKM:TITLE:" + data[0] + ";URL:" + 
                                    data[1] + ";;", 
    # phonebook or meCard should be a list of tuples like this: 
    # [('N', 'Name'), ('TEL', '231698890'), ...] 
    'phonebook': lambda data: "MECARD:" + ";".join([":".join(i)  
                                        for i in data]) + ";"
} 

From the above code, we observe the various data types that can be assigned and used while creating QR codes. For example, to use a bookmark as data we must provide data as a list, consisting of a title and the url. To accomplish this, we must do the following

# Python 2.x program to generate QR code 
from qrtools import QR 
  
# creates the QR object 
my_QR = QR(data = [u"geeksforgeeks", u"https://www.geeksforgeeks.org/"],  
                                      data_type = 'bookmark') 
  
# encodes to a QR code 
my_QR.encode() 

Read a QR code

Scanning and reading a QR code is relatively simple. While creating the QR object, we must simply specify the path to the QR code as an argument. Suppose we are trying to decode the QR code created at the beginning of the article.

# Python 2.x program to Scan and Read a QR code 
from qrtools import QR 
my_QR = QR(filename = "home/user/Desktop/qr.png") 
  
# decodes the QR code and returns True if successful 
my_QR.decode() 
  
# prints the data 
print my_QR.data 

Output :

Example

Read a QR code

We may also print the values of the other parameters passed while creating the QR object to generate the QR code, for example, using the same QR code generated at the beginning of the article, additionally adding these print statements would give the following additional output

print my_QR.data_type
print my_QR.pixel_size
print my_QR.margin_size

Output:

text
3
4

This article is contributed by Deepak Srivatsav. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.

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