Python PyQt5 basic application with widgets

Python PyQt Basic: Exercise-2 with Solution

Write a Python program to create a basic PyQt application that opens an empty window with a specified size and title. Add various widgets (e.g. label, push button) to the blank window. Widgets should display text or perform a simple action.

From doc.qt.io:

QApplication Class: The QApplication class manages the GUI application's control flow and main settings.

QMainWindow Class: The QMainWindow class provides a main application window.

QLabel Class: The QLabel widget provides a text or image display.

QPushButton: The push button, or command button, is perhaps the most commonly used widget in any graphical user interface. Push (click) a button to command the computer to perform some action, or to answer a question. Typical buttons are OK, Apply, Cancel, Close, Yes, No and Help.

QVBoxLayout Class: The QVBoxLayout class lines up widgets vertically.

QWidget: The QWidget class is the base class of all user interface objects.

Sample Solution:

Python Code:

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

def main():
    # Create a PyQt application
    app = QApplication(sys.argv)

    # Create a QMainWindow (main window)
    main_window = QMainWindow()
    # Set the window properties (title and initial size)
    main_window.setWindowTitle("Basic PyQt Application")
    main_window.setGeometry(100, 100, 400, 300)  # (x, y, width, height)
    # Create a central widget for the main window
    central_widget = QWidget()
    main_window.setCentralWidget(central_widget)
    # Create widgets (QLabel and QPushButton)
    label = QLabel("Example of PyQt label!")
    button = QPushButton("Example of PyQt pushbutton!")
    # Create a layout to arrange the widgets vertically
    layout = QVBoxLayout()
    layout.addWidget(label)
    layout.addWidget(button)
    # Set the layout for the central widget
    central_widget.setLayout(layout)
    # Show the window
    main_window.show()
    # Run the application's event loop
    sys.exit(app.exec_())
if __name__ == "__main__":
    main()

Explanation:

In the exercise above -

• Import the necessary modules from PyQt5.
• Create a "QApplication" object to manage application control flow and settings.
• Create a "QMainWindow" object for the main application window and set its title and initial size.
• Create a central widget (a QWidget) to hold our other widgets.
• Create two widgets: a QLabel displaying "Example of PyQt label!" and a QPushButton with the label "Example of PyQt pushbutton!".
• Create a vertical layout (QVBoxLayout) and add 'QLabel' and 'QPushButton' to it.
• Set the layout for the central widget so that it arranges the widgets vertically.
• Finally, start the application's event loop with app.exec_() to handle user interactions and events.

Output:

Flowchart:

Python Code Editor:

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