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An idiomatic GUI library inspired by Elm and based on gtk4-rs. Relm4 is a new version of relm that's built from scratch and is compatible with GTK4 and libadwaita.

Why Relm4

We believe that GUI development should be easy, productive and delightful.
The gtk4-rs crate already provides everything you need to write modern, beautiful and cross-platform applications. Built on top of this foundation, Relm4 makes developing more idiomatic, simpler and faster and enables you to become productive in just a few hours.

Our goals

Documentation

Dependencies

Relm4 depends on GTK4: How to install GTK4 and Rust

Ecosystem

Use this in to your Cargo.toml:

# Core library
relm4 = "0.9"
# Optional: reusable components
relm4-components = "0.9"
# Optional: icons (more info at https://github.com/Relm4/icons)
relm4-icons = "0.9.0"

Features

The relm4 crate has four feature flags:

FlagPurposeDefault
macrosEnable macros by re-exporting relm4-macros
libadwaitaImproved support for libadwaita-
libpanelImproved support for libpanel-
gnome_46Enable all version feature flags of all dependencies to match the GNOME 46 SDK-
gnome_45Enable all version feature flags of all dependencies to match the GNOME 45 SDK-
gnome_44Enable all version feature flags of all dependencies to match the GNOME 44 SDK-
gnome_43Enable all version feature flags of all dependencies to match the GNOME 43 SDK-
gnome_42Enable all version feature flags of all dependencies to match the GNOME 42 SDK

The macros feature is a default feature.

Examples

Several example applications are available at examples/.

📸 Screenshots from the example apps

A simple counter app

Simple app screenshot light Simple app screenshot dark

use gtk::prelude::*;
use relm4::prelude::*;

struct App {
    counter: u8,
}

#[derive(Debug)]
enum Msg {
    Increment,
    Decrement,
}

#[relm4::component]
impl SimpleComponent for App {
    type Init = u8;
    type Input = Msg;
    type Output = ();

    view! {
        gtk::Window {
            set_title: Some("Simple app"),
            set_default_size: (300, 100),

            gtk::Box {
                set_orientation: gtk::Orientation::Vertical,
                set_spacing: 5,
                set_margin_all: 5,

                gtk::Button {
                    set_label: "Increment",
                    connect_clicked => Msg::Increment,
                },

                gtk::Button {
                    set_label: "Decrement",
                    connect_clicked => Msg::Decrement,
                },

                gtk::Label {
                    #[watch]
                    set_label: &format!("Counter: {}", model.counter),
                    set_margin_all: 5,
                }
            }
        }
    }

    // Initialize the component.
    fn init(
        counter: Self::Init,
        root: Self::Root,
        sender: ComponentSender<Self>,
    ) -> ComponentParts<Self> {
        let model = App { counter };

        // Insert the code generation of the view! macro here
        let widgets = view_output!();

        ComponentParts { model, widgets }
    }

    fn update(&mut self, msg: Self::Input, _sender: ComponentSender<Self>) {
        match msg {
            Msg::Increment => {
                self.counter = self.counter.wrapping_add(1);
            }
            Msg::Decrement => {
                self.counter = self.counter.wrapping_sub(1);
            }
        }
    }
}

fn main() {
    let app = RelmApp::new("relm4.example.simple");
    app.run::<App>(0);
}

Projects using Relm4

License

Licensed under either of

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.

Feedback and contributions are highly appreciated!