#include <QtWidgets>

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

    QMainWindow mainWindow;

    QWidget *centralWidget = new QWidget;

    auto createLayout = [&mainWindow](QWidget *parent) -> QBoxLayout* {
        if (mainWindow.screen()->primaryOrientation() == Qt::LandscapeOrientation)
            return new QHBoxLayout(parent);
        return new QVBoxLayout(parent);
    };

    QBoxLayout *mainLayout = createLayout(centralWidget);
    centralWidget->setLayout(mainLayout);

    // Set up the menu bar.
    auto *menuBarMenu = new QMenu("Menu bar menu", mainWindow.menuBar());
    QAction action1("Menu item 1", centralWidget);
    QAction action2("Menu item 2", centralWidget);
    QAction action3("Menu item 3", centralWidget);
    menuBarMenu->addAction(&action1);
    menuBarMenu->addAction(&action2);
    menuBarMenu->addAction(&action3);
    mainWindow.menuBar()->addMenu(menuBarMenu);

    // Set up the context menu.
    QMenu contextMenu("Context menu", centralWidget);
    contextMenu.addAction(&action1);
    contextMenu.addAction(&action2);
    contextMenu.addAction(&action3);

    mainWindow.setContextMenuPolicy(Qt::CustomContextMenu);
    QObject::connect(&mainWindow, &QWidget::customContextMenuRequested,
                     &mainWindow, [&contextMenu, &mainWindow](const QPoint &pos) {
                         contextMenu.exec(mainWindow.mapToGlobal(pos));
                     });

    // Useful for opening the menu on systems that apparently don't emit customContextMenuRequested,
    // like Android: https://bugreports.qt.io/browse/QTBUG-122732
    auto *openContextMenuButton = new QPushButton("Open", centralWidget);
    QObject::connect(openContextMenuButton, &QPushButton::clicked, [&contextMenu, &mainWindow, openContextMenuButton](){
        contextMenu.move(mainWindow.geometry().center());
        contextMenu.show();
    });
    mainLayout->addWidget(openContextMenuButton);

    mainWindow.setCentralWidget(centralWidget);

    mainWindow.resize(400, 400);
    mainWindow.show();

    return app.exec();
}