gtk_rs_tutorial

gtk_rs_references_between_widgets.rs

/// references between widgets example
///
/// ref: https://gtk-rs.org/gtk4-rs/stable/latest/book/g_object_memory_management.html
use std::cell::Cell;
use std::rc::Rc;

use gtk::prelude::*;
use gtk::{
    glib::{self, clone},
    Application, ApplicationWindow, Button, Label,
};

const APP_ID: &str = "com.example.firstapp";

fn main() -> glib::ExitCode {
    let app = Application::builder().application_id(APP_ID).build();

    // Connect build_ui to "activate" signal of app
    app.connect_activate(build_ui);

    app.run()
}

fn build_ui(app: &Application) {
    let inc_button = Button::builder()
        .label("increase")
        .margin_top(12)
        .margin_bottom(12)
        .margin_start(12)
        .margin_end(12)
        .build();
    let dec_button = Button::builder()
        .label("decrease")
        .margin_top(12)
        .margin_bottom(12)
        .margin_start(12)
        .margin_end(12)
        .build();

    let number = Rc::new(Cell::new(0));

    let label = Label::builder()
        .label(number.get().to_string())
        .margin_top(12)
        .margin_bottom(12)
        .margin_start(12)
        .margin_end(12)
        .build();

    inc_button.connect_clicked(clone!(@weak number as n, @weak label => move |_| {
        n.set(n.get()+1);
        label.set_label(&n.get().to_string());
    }));
    // `number` keeps alive without `@weak number` or with `@strong number`
    dec_button.connect_clicked(clone!(@weak label => move |_| {
        number.set(number.get()-1);
        label.set_label(&number.get().to_string());
    }));

    // `gtk_box` holds all three widgets above
    let gtk_box = gtk::Box::builder()
        .orientation(gtk::Orientation::Horizontal)
        .build();
    gtk_box.append(&dec_button);
    gtk_box.append(&label);
    gtk_box.append(&inc_button);

    // create a window and set the title
    let window = ApplicationWindow::builder()
        .application(app)
        .title("my-gtk-app")
        .child(&gtk_box)
        .build();

    // Present window
    window.present();
}