Customizing widget behavior with PyQt event handling

Python PyQt Basic: Exercise-9 with Solution

Write a Python program that overrides a specific event handler to customize widget behavior using PyQt.

From doc.qt.io:

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

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

Qt module: PyQt5 is a set of Python bindings for the Qt application framework. It allows us to use Qt, a popular C++ framework, to create graphical user interfaces (GUIs) in Python.

Sample Solution:

Python Code:

import sys
from PyQt5.QtWidgets import QApplication, QWidget
from PyQt5.QtCore import Qt

class CustomWidget(QWidget):
    def __init__(self):
        super().__init__()

    def mousePressEvent(self, event):
        # Override the mousePressEvent to customize behavior
        if event.button() == Qt.LeftButton:
            print("Left mouse button clicked")
        elif event.button() == Qt.RightButton:
            print("Right mouse button clicked")

def main():
    app = QApplication(sys.argv)
    window = CustomWidget()
    window.setWindowTitle("Custom Widget Example")
    window.setGeometry(100, 100, 400, 300)
    window.show()
    sys.exit(app.exec_())

if __name__ == "__main__":
    main()

Explanation:

In the exercise above -

• Import the necessary modules.
• Create a custom widget class "CustomWidget" that inherits from "QWidget".
• Inside the CustomWidget class, we override the mousePressEvent event handler to customize its behavior. Depending on which mouse button was clicked (left or right), we print a message.
• In the main function, we create a "QApplication", instantiate our custom widget (CustomWidget), set the window's title and geometry, and show the window.
• When you run this program, it displays a window and start the application's event loop.
• When you click the left or right mouse button inside the widget, it prints a corresponding message to the console.

Output:

Left mouse button clicked
Left mouse button clicked
Right mouse button clicked
Left mouse button clicked
Right mouse button clicked

Flowchart:

Python Code Editor:

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