**Course Title:** Qt 6 Application Development with C++ **Section Title:** Styling and Theming Qt Applications **Topic:** Creating a custom-styled Qt application with dark mode and dynamic theming.(Lab topic) **Objective:** In this lab, you will learn how to create a custom-styled Qt application with dark mode and dynamic theming. By the end of this topic, you should be able to design and implement a visually appealing and user-friendly application that adapts to different themes. **Prerequisites:** * Familiarity with Qt 6 and C++ * Basic understanding of Qt Stylesheets (QSS) * Completion of previous topics, especially "Introduction to Qt's styling system and Qt Stylesheets (QSS)" and "Implementing dark mode and light mode themes" **Lab Overview:** In this lab, you will create a custom-styled Qt application with dark mode and dynamic theming. You will learn how to: 1. Create a custom stylesheet for dark mode 2. Implement dynamic theming using QSS 3. Switch between dark and light modes at runtime **Step 1: Create a Custom Stylesheet for Dark Mode** To create a custom stylesheet for dark mode, you will need to define the colors, fonts, and styles for your application's widgets. You can use Qt Designer to create a QSS file or manually write the stylesheet code. Here's an example of a QSS file for dark mode: ```qss /* darkmode.qss */ QWidget { background-color: #2f2f2f; color: #ffffff; } QPushButton { background-color: #4f4f4f; color: #ffffff; border: 1px solid #5f5f5f; } QLineEdit { background-color: #3f3f3f; color: #ffffff; border: 1px solid #5f5f5f; } ``` Save this QSS file as `darkmode.qss` in your project directory. **Step 2: Implement Dynamic Theming using QSS** To implement dynamic theming, you will need to create a QSS file for each theme (dark and light) and load them dynamically using the `setStyleSheet()` function. Here's an example of how to load the QSS file dynamically: ```cpp void MyWindow::setDarkMode() { QFile file("darkmode.qss"); file.open(QFile::ReadOnly); QString styleSheet = QLatin1String(file.readAll()); file.close(); setStyleSheet(styleSheet); } void MyWindow::setLightMode() { QFile file("lightmode.qss"); file.open(QFile::ReadOnly); QString styleSheet = QLatin1String(file.readAll()); file.close(); setStyleSheet(styleSheet); } ``` **Step 3: Switch between Dark and Light Modes at Runtime** To switch between dark and light modes at runtime, you can use a QPushButton to trigger the theme switch. Here's an example of how to switch between dark and light modes: ```cpp void MyWindow::onSwitchThemeButtonClicked() { if (isDarkMode) { setLightMode(); } else { setDarkMode(); } isDarkMode = !isDarkMode; } ``` **Conclusion:** In this lab, you created a custom-styled Qt application with dark mode and dynamic theming. You learned how to create a custom stylesheet for dark mode, implement dynamic theming using QSS, and switch between dark and light modes at runtime. **Practice Exercise:** * Create a custom stylesheet for light mode. * Implement the light mode and switch between dark and light modes at runtime. **Resources:** * Qt Documentation: [Qt Stylesheets (QSS)](https://doc.qt.io/qt-6/stylesheet.html) * Qt Blog: [Dynamic Stylesheets in Qt](https://blog.qt.io/blog/2019/01/14/dynamic-stylesheets-qt/) **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.