Python PyQt custom widget with keyboard shortcuts

Python PyQt Event Handling: Exercise-5 with Solution

Write a Python program that creates a custom widget in PyQt and implements a custom keyboard shortcuts by overriding the key press method.

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.

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

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

QShortcut Class: The QShortcut class is used to create keyboard shortcuts.

QKeySequence Class: The QKeySequence class encapsulates a key sequence as used by shortcuts.

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, QMainWindow, QWidget, QLabel, QShortcut
from PyQt5.QtGui import QKeySequence
from PyQt5.QtCore import Qt

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

        self.setGeometry(100, 100, 400, 200)
        self.setWindowTitle("Custom Widget with Keyboard Shortcuts")

        self.label = QLabel("Press 'P' for Action 1, 'J' for Action 2", self)
        self.label.setGeometry(10, 10, 300, 30)

        # Create shortcuts for 'P' and 'J' keys
        self.shortcut_P = QShortcut(QKeySequence(Qt.Key_P), self)
        self.shortcut_J = QShortcut(QKeySequence(Qt.Key_J), self)

        # Connect shortcuts to actions
        self.shortcut_P.activated.connect(self.action_1)
        self.shortcut_J.activated.connect(self.action_2)

    def action_1(self):
        self.label.setText("Action 1 triggered!")

    def action_2(self):
        self.label.setText("Action 2 triggered!")

class CustomWidgetApp(QMainWindow):
    def __init__(self):
        super().__init__()

        self.setWindowTitle("Custom Widget Example")
        self.setGeometry(100, 100, 400, 200)

        custom_widget = CustomWidget()
        self.setCentralWidget(custom_widget)

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

if __name__ == "__main__":
    main()

Explanation:

In the exercise above -

• Import the necessary PyQt5 modules.
• Create a custom widget class called "CustomWidget" by subclassing the standard "QWidget".
• Inside the "CustomWidget" class, we override the "keyPressEvent" method. This method is called when a key is pressed while the widget has focus.
• Within the overridden keyPressEvent method, we check which key was pressed using event.key() and respond accordingly. Here we check for 'P' or 'p' to trigger Action 1 and 'J' or 'j' to trigger Action 2. When an action is triggered, we update a "QLabel" to display the corresponding message.
• Finally create an instance of the "CustomWidget" class in the "CustomWidgetApp" class, which represents our main application window.

Output:

Flowchart:

Python Code Editor:

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