Capture and display mouse events in PyQt5 with Python

Python PyQt Event Handling: Exercise-2 with Solution

Write a Python program that captures and displays mouse events like clicks and movements using PyQt5.

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.

QWidget Class: 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.

QEvent Class: The QEvent class is the base class of all event classes. Event objects contain event parameters.

Sample Solution:

Python Code:

import sys
from PyQt5.QtWidgets import QApplication, QMainWindow, QLabel, QWidget
from PyQt5.QtCore import Qt, QEvent
class MouseEventApp(QMainWindow):
    def __init__(self):
        super().__init__()

        self.setWindowTitle("Mouse Event Example")
        self.setGeometry(100, 100, 400, 200)

        self.central_widget = QWidget(self)
        self.setCentralWidget(self.central_widget)

        self.mouse_label = QLabel("Mouse Events:", self.central_widget)
        self.mouse_label.setGeometry(10, 10, 200, 30)

        self.mouse_tracker_label = QLabel("", self.central_widget)
        self.mouse_tracker_label.setGeometry(10, 40, 300, 30)

        # Install an event filter to capture mouse events
        self.central_widget.installEventFilter(self)

    def eventFilter(self, obj, event):
        if event.type() == QEvent.MouseMove:
            x = event.x()
            y = event.y()
            self.mouse_tracker_label.setText(f"Mouse moved to ({x}, {y})")

        elif event.type() == QEvent.MouseButtonPress:
            button = ""
            if event.button() == Qt.LeftButton:
                button = "Left"
            elif event.button() == Qt.RightButton:
                button = "Right"
            elif event.button() == Qt.MiddleButton:
                button = "Middle"

            self.mouse_tracker_label.setText(f"{button} button clicked")

        return super().eventFilter(obj, event)

def main():
    app = QApplication(sys.argv)
    window = MouseEventApp()
    window.show()
    sys.exit(app.exec_())

if __name__ == "__main__":
    main()

Explanation:

In the exercise above -

• Import the necessary PyQt5 modules.
• Create a custom class MouseEventApp that inherits from QMainWindow.
• Inside the MouseEventApp class constructor (__init__), we set up the main window, labels to display mouse events, and install an event filter on the central widget.
• The eventFilter() function captures mouse events, specifically mouse movements and button clicks. When a mouse event occurs, the labels are updated accordingly.
• We create an instance of the MouseEventApp class, show the main window, and start the PyQt5 application event loop.

Output:

Flowchart:

Python Code Editor:

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