如何对QTreeView中的文件类型使用系统默认图标

#include <QApplication>
#include <QTreeView>
#include <QStandardItemModel>
#include <QStyledItemDelegate>
#include <QFileIconProvider>

class FileIconDelegate : public QStyledItemDelegate
{
public:
    explicit FileIconDelegate(QObject* parent = nullptr)
        : QStyledItemDelegate(parent)
    {
    }

    void paint(QPainter* painter, const QStyleOptionViewItem& option, const QModelIndex& index) const override
    {
        QStyleOptionViewItem opt = option;
        initStyleOption(&opt, index);

        if (index.column() == 0) {
            QFileIconProvider iconProvider;
            QIcon icon = iconProvider.icon(QFileIconProvider::File);
            opt.icon = icon;
        }

        QStyledItemDelegate::paint(painter, opt, index);
    }
};

int main(int argc, char** argv)
{
    QApplication app(argc, argv);

    QTreeView treeView;
    QStandardItemModel model;
    treeView.setModel(&model);

    // 添加文件数据到模型中
    // ...

    // 设置自定义的委托
    FileIconDelegate delegate;
    treeView.setItemDelegate(&delegate);

    treeView.show();

    return app.exec();
}