Building QR Code Generator Application using PyQt5

In this article we will see how we can make a QR code generator application using PyQt5. A QR code is a type of matrix barcode first designed in 1994 for the automotive industry in Japan. A barcode is a machine-readable optical label that contains information about the item to which it is attached. Below is how the application will look like

In order to make this we will use the libraries given below
PyQt5 is cross-platform GUI toolkit, a set of python bindings for Qt v5. One can develop an interactive desktop application with so much ease because of the tools and simplicity provided by this library. Below is the command to install the PyQt5

pip install PyQt5

qrcode :For generating a Quick Response code is a two-dimensional pictographic code used for its fast readability and comparatively large storage capacity. The code consists of black modules arranged in a square pattern on a white background. The information encoded can be made up of any kind of data (e.g., binary, alphanumeric, or Kanji symbols). Below is the command to install the qrcode module

pip install qrcode

Implementation Steps :
1. Create a Image class which inherits qrcode base image 
2. Inside the Image class, get the size from the border and width and override the painter event and create a initial image and fill it with white color 
3. Create a main window class 
4. Inside the window class create a label which will show the QR code image 
5. Create a line edit to receive the text from the user 
6. Add label and line edit to the vertical layout and set layout to the window 
7. Add action to the line edit when entered is pressed 
8. Inside the line edit action get the text of the line edit 
9. Create a pixmap image of the line edit text and use Image class as image_factory 
10. Set the pixmap i.e QR code image to the label

Below is the implementation 

Python3

# importing libraries
from PyQt5.QtWidgets import *
from PyQt5 import QtCore, QtGui
from PyQt5.QtGui import *
from PyQt5.QtCore import *
import qrcode
import sys

# Image class for QR code
class Image(qrcode.image.base.BaseImage):

    # constructor
    def __init__(self, border, width, box_size):

        # assigning border
        self.border = border

        # assigning  width
        self.width = width

        # assigning box size
        self.box_size = box_size

        # creating size
        size = (width + border * 2) * box_size

        # image
        self._image = QImage(size, size, QImage.Format_RGB16)

        # initial image as white
        self._image.fill(Qt.white)


    # pixmap method
    def pixmap(self):

        # returns image
        return QPixmap.fromImage(self._image)

    # drawrect method for drawing rectangle
    def drawrect(self, row, col):

        # creating painter object
        painter = QPainter(self._image)

        # drawing rectangle
        painter.fillRect(
            (col + self.border) * self.box_size,
            (row + self.border) * self.box_size,
            self.box_size, self.box_size,
            QtCore.Qt.black)


# Main Window class
class Window(QMainWindow):

    # constructor
    def __init__(self):
        QMainWindow.__init__(self)

        # setting window title
        self.setWindowTitle("QR Code")

        # setting geometry
        self.setGeometry(100, 100, 300, 300)

        # creating a label to show the qr code
        self.label = QLabel(self)

        # creating a line edit to receive text
        self.edit = QLineEdit(self)

        # adding action when entered is pressed
        self.edit.returnPressed.connect(self.handleTextEntered)

        # setting font to the line edit
        self.edit.setFont(QFont('Times', 9))

        # setting alignment
        self.edit.setAlignment(Qt.AlignCenter)

        # creating a vertical layout
        layout = QVBoxLayout(self)

        # adding label to the layout
        layout.addWidget(self.label)

        # adding line edit to the layout
        layout.addWidget(self.edit)

        # creating a QWidget object
        widget = QWidget()

        # setting layout to the widget
        widget.setLayout(layout)

        # setting widget as central widget to the main window
        self.setCentralWidget(widget)


    # method called by the line edit
    def handleTextEntered(self):

        # get the text
        text = self.edit.text()

        # creating a pix map of qr code
        qr_image = qrcode.make(text, image_factory = Image).pixmap()

        # set image to the label
        self.label.setPixmap(qr_image)




# create pyqt5 app
app = QApplication(sys.argv)

# create the instance of our Window
window = Window()

# showing window
window.show()

# start the app
sys.exit(app.exec_())

Output :

When user entered  the text in the line edit and press enter key, QR code will be displayed and window size will get adjusted according to the size of QR code