Learn how to create PyQt desktop applications with Python

PyQt is a set of Python bindings for the Qt application framework from Digia. Qt is a powerful cross-platform application development framework widely used for the development of graphical user interfaces (GUIs) and desktop applications. PyQt allows you to create desktop applications in Python using the Qt GUI toolkit.

In this tutorial, we will learn how to create desktop applications using PyQt and Python. We will cover the basics of PyQt, including how to install it, create a simple application, and add widgets to create a fully functional GUI.

Prerequisites:

1. Python installed on your computer
2. PyQt5 library installed
3. Basic understanding of Python programming

Installing PyQt:
To install PyQt5, you can use pip, the Python package manager. Open your command prompt or terminal and run the following command:

pip install PyQt5

Creating a Simple PyQt Application:
Now that you have PyQt installed, let’s create a simple PyQt application. Open your favorite text editor or IDE and create a new Python script (e.g., myapp.py). In this script, we will create a simple window with a label.

import sys
from PyQt5.QtWidgets import QApplication, QWidget, QLabel

# Create an instance of the QApplication
app = QApplication(sys.argv)

# Create a QWidget instance
window = QWidget()

# Set window title
window.setWindowTitle("My First PyQt App")

# Set window size
window.resize(400, 200)

# Create a QLabel widget
label = QLabel("Hello World!", window)

# Show the window
window.show()

# Execute the application
sys.exit(app.exec_())

Save the script and run it using Python. You should see a window with a label displaying "Hello World!". This code creates a simple PyQt application with a window and a label widget.

Adding Widgets to the Application:
Now that you have created a basic PyQt application, let’s add more widgets to make it more interactive. PyQt provides a wide range of widgets that you can use to create powerful GUIs.

Here’s an example of adding a button widget to our simple application:

import sys
from PyQt5.QtWidgets import QApplication, QWidget, QLabel, QPushButton

# Create an instance of the QApplication
app = QApplication(sys.argv)

# Create a QWidget instance
window = QWidget()

# Set window title
window.setWindowTitle("My First PyQt App")

# Set window size
window.resize(400, 200)

# Create a QLabel widget
label = QLabel("Hello World!", window)

# Create a QPushButton widget
button = QPushButton("Click Me!", window)
button.move(150, 100)

# Show the window
window.show()

# Execute the application
sys.exit(app.exec_())

This code adds a button widget to the window and moves it to a specific position. When you run the script, you should see a button labeled "Click Me!" below the label.

Handling Events:
In PyQt, you can handle events, such as button clicks, using signals and slots. Signals are emitted when a particular event occurs, and slots are functions that are called in response to signals.

Let’s add an event handler for the button click event:

import sys
from PyQt5.QtWidgets import QApplication, QWidget, QLabel, QPushButton

# Create an instance of the QApplication
app = QApplication(sys.argv)

# Create a QWidget instance
window = QWidget()

# Set window title
window.setWindowTitle("My First PyQt App")

# Set window size
window.resize(400, 200)

# Create a QLabel widget
label = QLabel("Hello World!", window)

# Create a QPushButton widget
button = QPushButton("Click Me!", window)
button.move(150, 100)

# Event handler for button click
def on_button_click():
    label.setText("Button Clicked!")

# Connect the button click event to the event handler
button.clicked.connect(on_button_click)

# Show the window
window.show()

# Execute the application
sys.exit(app.exec_())

Now when you click the button, the label text will change to "Button Clicked!". This is achieved by connecting the clicked signal of the button widget to the on_button_click function using the clicked.connect() method.

Conclusion:
In this tutorial, we learned how to create desktop applications using PyQt and Python. We covered the basics of PyQt, including how to install it, create a simple application, add widgets, and handle events.

PyQt provides a rich set of widgets and functionalities for building powerful desktop applications with a modern GUI. Experiment with different widgets and event handling to create interactive applications tailored to your needs.

I hope this tutorial has been helpful in getting started with PyQt desktop apps with Python. Happy coding!