Python PyQt button click example

Python PyQt Connecting Signals to Slots: Exercise-6 with Solution

Write a Python program that creates a button and when clicked it prints a message. Use the PyQt module.

From doc.qt.io:

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

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

QPushButton Class: The QPushButton widget provides a command button.

QVBoxLayout Class: The QVBoxLayout class lines up widgets vertically.

Sample Solution:

Python Code:

import sys
from PyQt5.QtWidgets import QApplication, QWidget, QPushButton, QVBoxLayout
from PyQt5.QtCore import pyqtSignal

class CustomWidget(QWidget):
    # Define a custom signal
    button_clicked = pyqtSignal()

    def __init__(self):
        super().__init__()

        layout = QVBoxLayout()

        # Create a custom button
        self.custom_button = QPushButton("Custom Button", self)
        layout.addWidget(self.custom_button)

        # Connect the button's clicked signal to the custom signal
        self.custom_button.clicked.connect(self.button_clicked)

        self.setLayout(layout)

def custom_slot():
    print("The custom button is clicked.")

def main():
    app = QApplication(sys.argv)
    window = CustomWidget()
    window.setWindowTitle("Custom Widget Example")
    window.setGeometry(100, 100, 400, 200)  # (x, y, width, height)
    
    # Connect the custom signal to the custom slot
    window.button_clicked.connect(custom_slot)
    
    window.show()
    sys.exit(app.exec_())

if __name__ == "__main__":
    main()

Explanation:

In the exercise above -

• Import the necessary modules from PyQt5.
• Create a custom "QWidget" class named "CustomWidget" that inherits from "QWidget". Inside this class, we define a custom signal called "button_clicked".
• Design a custom button called self.custom_button and connect its clicked signal to the custom ‘button_clicked’ signal.
• Define a custom slot function called "custom_slot()" that reacts to button presses. In this case, it prints a message when the button is clicked.
• In the main function, we create the PyQt application, instantiate the "CustomWidget" class, set the window properties, and display the main window.

Output:

The custom button is clicked.
The custom button is clicked.
The custom button is clicked.

Flowchart:

Python Code Editor:

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