Gtk :: Layout中的gtkmm居中小部件

Question

I'm trying to create a fullscreen window covered with an image and one entry widget in the middle of the window.

I already have the fullscreen window with the image, however, I'm struggling with positioning the entry box exactly in the middle of the window. I tried Gtk::Alignment , Gtk::VBox , Gtk::HBox , Gtk::Table and many other containers, but to be honest, I don't really understand all the containers how do they behave. I am used to WIN32 API with absolute positioning and this is way different. I know I can use something like fixed positioning in Gtk/gtkmm, however, it does not seem like the cleanest solution to me.

class App : public Gtk::Window {
public:
    [...]
    App() {
        fullscreen();
        Gdk::Rectangle rec = get_screen()->get_monitor_workarea(get_screen()->get_primary_monitor());
        set_default_size(rec.get_width(), rec.get_height());
        show();

        m_bgImage.set("image.jpg");
        m_layout.add(m_bgImage);

        m_entry.set_size_request(300, 30);
        m_entry.set_opacity(0.5);
        m_entry.set_visibility(false);
        m_entry.signal_activate().connect(sigc::mem_fun(*this, &PadlockGui::onPasswordEntryReturn));
        m_entry.set_icon_from_icon_name("edit-clear", Gtk::ENTRY_ICON_SECONDARY);
        m_entry.signal_icon_press().connect(sigc::mem_fun(*this, &PadlockGui::clearPasswordEntry));

        m_layout.add(m_entry);
        add(m_layout);

        show_all_children();
    }

private:
    Gtk::Layout m_layout;
    Gtk::Image m_bgImage;
    Gtk::Entry m_entry;
    [...]
};

Here is a picture of my current situation:

Here is what I am trying to achieve:

Answer 1

I would suggest using CSS to create the background image rather than Gtk::Image . Then you can just put the entry directly in the window, and make sure its expand property is set to false and its halign and valign properties are centered.