**Course Title:** PySide6 Application Development **Section Title:** Styling and Theming Applications **Topic:** Dark mode implementation **Introduction** Dark mode has become a popular feature in many modern applications, allowing users to switch to a darker color scheme for reduced eye strain and improved readability. In this topic, we'll explore how to implement dark mode in your PySide6 application using Qt Stylesheets and the built-in theme management features. **Understanding Qt's Theme Management** Qt has built-in support for theme management, allowing you to switch between different themes at runtime. The `QApplication` class has a `setStyle()` method that allows you to set a specific style for your application, and the `setPalette()` method that sets the color palette for your application. To implement dark mode, we'll use a combination of Qt Stylesheets and the `QApplication` styles. **Implementing Dark Mode using Qt Stylesheets** One way to implement dark mode is to use Qt Stylesheets with a CSS-like syntax. You can define a separate stylesheet for dark mode and load it when the user switches to dark mode. Here's an example of a dark mode stylesheet: ```css /* darkmode.qss */ QPushButton { background-color: #2f2f2f; color: #ffffff; } QPushButton:hover { background-color: #3f3f3f; } QLabel { color: #ffffff; } QLineEdit { background-color: #2f2f2f; color: #ffffff; border: 1px solid #2f2f2f; } QLineEdit:focus { background-color: #3f3f3f; } ``` To load the stylesheet, you can use the `QApplication.setStyleSheet()` method: ```python import sys from PySide6 import QtWidgets, QtCore app = QtWidgets.QApplication(sys.argv) # Load dark mode stylesheet app.setStyleSheet(open("darkmode.qss", "r").read()) # Create a sample window window = QtWidgets.QWidget() button = QtWidgets.QPushButton("Click me", window) window.show() sys.exit(app.exec()) ``` **Using Built-in Themes** Qt provides a built-in dark mode theme, which can be set using the `QStyleFactory` class. You can use the `QStyleFactory.create()` method to create a `QStyle` object with a specific theme. Here's an example of setting the built-in dark mode theme: ```python import sys from PySide6 import QtWidgets, QtCore app = QtWidgets.QApplication(sys.argv) # Set built-in dark mode theme style = QtWidgets.QStyleFactory.create("Fusion") app.setStyle(style) app.setPalette(QtWidgets.QApplication.style().standardPalette()) # Create a sample window window = QtWidgets.QWidget() button = QtWidgets.QPushButton("Click me", window) window.show() sys.exit(app.exec()) ``` **Switching between Dark and Light Modes** To switch between dark and light modes, you can use a toggle button or a menu item. When the user toggles the button or clicks the menu item, you can load the corresponding stylesheet or set the built-in theme. Here's an example of a toggle button: ```python import sys from PySide6 import QtWidgets, QtCore class DarkModeToggle(QtWidgets.QPushButton): def __init__(self): super().__init__("Toggle Dark Mode") self.isActive = False self.clicked.connect(self.toggle) def toggle(self): if not self.isActive: app.setStyleSheet(open("darkmode.qss", "r").read()) self.isActive = True else: app.setStyleSheet("") self.isActive = False app = QtWidgets.QApplication(sys.argv) window = QtWidgets.QWidget() toggle_button = DarkModeToggle() window_layout = QtWidgets.QVBoxLayout() window_layout.addWidget(toggle_button) window.setLayout(window_layout) window.show() sys.exit(app.exec()) ``` **Conclusion** In this topic, we've covered the basics of implementing dark mode in your PySide6 application using Qt Stylesheets and built-in theme management features. You can use these techniques to create a user-friendly and visually appealing dark mode experience for your users. **What's next?** In the next topic, we'll cover dynamic theming, which allows you to switch between different themes at runtime. You'll learn how to create a theme manager class that loads and switches between different themes using Qt Stylesheets and built-in theme management features. **References** * Qt Documentation: [Qt Stylesheets](https://doc.qt.io/qt-6/stylesheet-syntax.html) * Qt Documentation: [Theme Management](https://doc.qt.io/qt-6/theme-management.html) **Leave a comment or ask for help** If you have any questions or need further clarification on any of the concepts covered in this topic, feel free to leave a comment below. I'll be happy to help you out!