Update the values of child objects at runtime

Question

How I can update child widget of gtk::Grid (gtk::Label in example) in runtime?

In example code after change value SpinButton, I add recreated Grid (fn grid()) with updated childs (I don't want remove old Grid in example).

In a real project I need to add a Grid with an updateable child element Label without recreate Grid. New values will be continuously read from the database.

Example:

pub fn test(parent: &gtk::Box) {
    let parent_grid = gtk::Grid::new();
    let parent_spin = gtk::SpinButton::with_range(0.0, 10.0, 1.0);
    parent_grid.add(&parent_spin);

    let parent_value = Rc::new(RefCell::new(0));
    let parent_value_clone = parent_value.clone();
    let parent_grid_rc = Rc::new(RefCell::new(parent_grid));
    let parent_grid_rc_clone = parent_grid_rc.clone();

    parent_spin.connect_value_changed(move |x| {
        *parent_value_clone.borrow_mut() = x.value_as_int();
        (*parent_grid_rc_clone.borrow_mut()).add(&grid(*parent_value.borrow()));
    });

    (*parent_grid_rc.borrow()).show_all();
    parent.add(&(*parent_grid_rc.borrow()));
}

fn grid(value: i32) -> gtk::Grid {
    let grid = gtk::Grid::new();
    let label_box = gtk::Label::new(Some("Value: "));
    let value_box = Rc::new(RefCell::new(gtk::Label::new(Some(&format!("{}", value)))));  // THIS LABEL MUST BE UPDATED DURING RUNTIME
    grid.add(&label_box);
    grid.add(&(*value_box.borrow()));
    grid.show_all();
    grid
}

I'm new to this, so if there are other methods for creating dynamic objects in Rust-GTK and modifying their children, I'd love to hear about them.

Aiany · Accepted Answer · 2022-06-21 22:32:43Z

Library glib helped me in my trouble. I didn't find any clear examples on the internet, so let my solution be here.

pub fn test(parent: &gtk::Box) {
    let parent_grid = gtk::Grid::new();
    let parent_spin = gtk::SpinButton::with_range(0.0, 10.0, 1.0);
    parent_grid.add(&parent_spin);

    let parent_value = Rc::new(RefCell::new(0));
    let parent_value_clone = parent_value.clone();

    parent_spin.connect_value_changed(move |x| {
        *parent_value_clone.borrow_mut() = x.value_as_int();
    });

    let grid = gtk::Grid::new();
    let label_box = gtk::Label::new(Some("Value: "));
    let value_box = gtk::Label::new(Some("Value"));
    grid.add(&label_box);
    grid.add(&value_box);
    grid.show_all();

    let update_label = move || {
        println!("value={}", *parent_value.borrow());
        value_box.set_text(&format!("{}",*parent_value.borrow()));
        glib::Continue(true)
    };
    glib::timeout_add_seconds_local(2, update_label);

    parent_grid.add(&grid);
    parent_grid.show_all();
    parent.add(&parent_grid);
}



fn grid(value: Rc<RefCell<i32>>) -> (gtk::Grid) {
    let grid = gtk::Grid::new();
    let label_box = gtk::Label::new(Some("Value: "));
    let value_box = gtk::Label::new(Some("Value"));
    grid.add(&label_box);
    grid.add(&value_box);
    let value = *value.borrow();

    grid.show_all();
    let update_label = move || {
        value_box.set_text(&format!("{}",value));
        glib::Continue(true)
    };
glib::timeout_add_seconds_local(1, update_label);
    grid
}

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