**Course Title:** Qt 6 Application Development with C++ **Section Title:** Advanced Widgets and Custom Forms **Topic:** Exploring advanced widgets: QComboBox, QListWidget, QTableWidget, QTreeView. In this topic, we will delve into the world of advanced widgets in Qt 6, exploring the features and usage of four essential widgets: QComboBox, QListWidget, QTableWidget, and QTreeView. By the end of this section, you will be able to effectively utilize these widgets to create more complex and interactive GUI applications. ### 1. QComboBox QComboBox is a versatile widget that allows users to select from a drop-down list of options. It can be used to provide users with a range of choices, such as selecting a font size or choosing a country from a list. **Example Code:** ```cpp #include <QApplication> #include <QComboBox> #include <QVBoxLayout> #include <QLabel> int main(int argc, char *argv[]) { QApplication app(argc, argv); QWidget window; QVBoxLayout layout(&window); QLabel label("Select a color:"); QComboBox comboBox; comboBox.addItem("Red"); comboBox.addItem("Green"); comboBox.addItem("Blue"); layout.addWidget(&label); layout.addWidget(&comboBox); window.show(); return app.exec(); } ``` In this example, we create a QComboBox and add three items to it. The user can then select one of the colors from the drop-down list. **Key Concepts:** * QComboBox can be used to provide users with a range of choices. * Use addItem() to add items to the combo box. ### 2. QListWidget QListWidget is a widget that displays a list of items, allowing users to select and interact with them. **Example Code:** ```cpp #include <QApplication> #include <QListWidget> #include <QVBoxLayout> #include <QPushButton> int main(int argc, char *argv[]) { QApplication app(argc, argv); QWidget window; QVBoxLayout layout(&window); QListWidget listWidget; listWidget.addItem("Item 1"); listWidget.addItem("Item 2"); listWidget.addItem("Item 3"); QPushButton addButton("Add Item"); QPushButton removeButton("Remove Item"); layout.addWidget(&listWidget); layout.addWidget(&addButton); layout.addWidget(&removeButton); connect(&addButton, &QPushButton::clicked, [&listWidget]() { listWidget.addItem("New Item"); }); connect(&removeButton, &QPushButton::clicked, [&listWidget]() { listWidget.takeItem(listWidget.currentRow()); }); window.show(); return app.exec(); } ``` In this example, we create a QListWidget and add three items to it. We also create two buttons: one to add a new item and one to remove the selected item. **Key Concepts:** * QListWidget can be used to display a list of items. * Use addItem() to add items to the list widget. * Use takeItem() to remove the selected item. ### 3. QTableWidget QTableWidget is a widget that displays data in a table format, allowing users to interact with the data. **Example Code:** ```cpp #include <QApplication> #include <QTableWidget> #include <QVBoxLayout> #include <QPushButton> int main(int argc, char *argv[]) { QApplication app(argc, argv); QWidget window; QVBoxLayout layout(&window); QTableWidget tableWidget(3, 3); for (int i = 0; i < 3; i++) { for (int j = 0; j < 3; j++) { QTableWidgetItem *item = new QTableWidgetItem(QString("Cell (%0,%1)").arg(i).arg(j)); tableWidget.setItem(i, j, item); } } QPushButton addButton("Add Row"); QPushButton removeButton("Remove Row"); layout.addWidget(&tableWidget); layout.addWidget(&addButton); layout.addWidget(&removeButton); connect(&addButton, &QPushButton::clicked, [&tableWidget]() { tableWidget.insertRow(tableWidget.rowCount()); }); connect(&removeButton, &QPushButton::clicked, [&tableWidget]() { tableWidget.removeRow(tableWidget.rowCount() - 1); }); window.show(); return app.exec(); } ``` In this example, we create a QTableWidget with 3 rows and 3 columns. We populate the table with some initial data. We also create two buttons: one to add a new row and one to remove the last row. **Key Concepts:** * QTableWidget can be used to display data in a table format. * Use setItem() to add items to the table widget. * Use insertRow() to add a new row. * Use removeRow() to remove a row. ### 4. QTreeView QTreeView is a widget that displays data in a tree-like structure, allowing users to interact with the data. **Example Code:** ```cpp #include <QApplication> #include <QFileSystemModel> #include <QTreeView> #include <QVBoxLayout> int main(int argc, char *argv[]) { QApplication app(argc, argv); QWidget window; QVBoxLayout layout(&window); QFileSystemModel model; model.setRootPath("/"); QTreeView treeView; treeView.setModel(&model); layout.addWidget(&treeView); window.show(); return app.exec(); } ``` In this example, we create a QFileSystemModel to display the file system. We create a QTreeView and set the model. The tree view will display the file system in a tree-like structure. **Key Concepts:** * QTreeView can be used to display data in a tree-like structure. * Use setModel() to set the model for the tree view. By mastering these advanced widgets, you will be able to create complex and interactive GUI applications. In the next topic, we will explore how to customize input forms with validators. **Practical Takeaways:** * QComboBox, QListWidget, QTableWidget, and QTreeView are powerful widgets that can be used to display and interact with data in various ways. * Each widget has its own strengths and weaknesses, and choosing the right widget for the job is crucial. * By using these widgets effectively, you can create complex and interactive GUI applications. **Links for Further Learning:** * [Qt Documentation: QComboBox](https://doc.qt.io/qt-6/qcombobox.html) * [Qt Documentation: QListWidget](https://doc.qt.io/qt-6/qlistwidget.html) * [Qt Documentation: QTableWidget](https://doc.qt.io/qt-6/qtablewidget.html) * [Qt Documentation: QTreeView](https://doc.qt.io/qt-6/qtreeview.html) Do you have any questions about this topic? Please leave a comment below.