<h1>
<img src="assets/Relm_logo_with_text.png" width="190" alt="Relm4">
</h1>
[](https://github.com/Relm4/relm4/actions/workflows/rust.yml)
[](https://matrix.to/#/#relm4:matrix.org)
[](https://crates.io/crates/relm4)
[](https://docs.rs/relm4/)
[](https://relm4.org/book/stable/)
[](https://deps.rs/repo/github/Relm4/relm4)
An idiomatic GUI library inspired by [Elm](https://elm-lang.org/) and based on [gtk4-rs](https://crates.io/crates/gtk4).
Relm4 is a new version of [relm](https://github.com/antoyo/relm) that's built from scratch and is compatible with [GTK4](https://www.gtk.org/) and [libadwaita](https://gitlab.gnome.org/GNOME/libadwaita).
## Why Relm4
We believe that GUI development should be easy, productive and delightful.
The [gtk4-rs](https://crates.io/crates/gtk4) 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
+ ⏱️ **Productivity**
+ ✨ **Simplicity**
+ 📎 **Outstanding documentation**
+ 🔧 **Maintainability**
## Documentation
+ 📖 **[The Relm4 book](https://relm4.org/book/stable/)**
+ 📜 **[Rust documentation](https://docs.rs/relm4/)**
## Need help?
If you find yourself having trouble with anything, feel free to ask questions at:
- [GitHub Discussions](https://github.com/Relm4/Relm4/discussions)
- [Matrix](https://matrix.to/#/#relm4:matrix.org)
## Dependencies
Relm4 depends on GTK4: [How to install GTK4](https://www.gtk.org/docs/installations/).
## Ecosystem
Relm4 has two crates that extend the core functionality:
+ [relm4-macros](https://crates.io/crates/relm4-macros) provides a `widget` macro that simplifies UI creation
+ [relm4-components](https://crates.io/crates/relm4-components) is a collections of reusable components you can easily integrate into your application
To use all features, just add this to your `Cargo.toml`:
```toml
relm4 = { version = "0.4", features = ["macros"] }
relm4-components = "0.4"
```
### Features
The `relm4` crate has four feature flags:
| macros | Enable macros by re-exporting [`relm4-macros`](https://crates.io/crates/relm4-macros) |
| tokio-rt | Adds the [`AsyncRelmWorker`](https://docs.rs/relm4/struct.AsyncRelmWorker.html) type that uses an asynchronous update function |
| libadwaita | Improved support for [libadwaita](https://gitlab.gnome.org/World/Rust/libadwaita-rs) |
| all | Enable all features |
## Examples
Several example applications are available at [relm4-examples/](relm4-examples/).
#### [📸 Screenshots from the example apps](assets/screenshots)
### A simple counter app
```rust
use gtk::prelude::{BoxExt, ButtonExt, GtkWindowExt, OrientableExt};
use relm4::{send, AppUpdate, Model, RelmApp, Sender, WidgetPlus, Widgets};
#[derive(Default)]
struct AppModel {
counter: u8,
}
enum AppMsg {
Increment,
Decrement,
}
impl Model for AppModel {
type Msg = AppMsg;
type Widgets = AppWidgets;
type Components = ();
}
impl AppUpdate for AppModel {
fn update(&mut self, msg: AppMsg, _components: &(), _sender: Sender<AppMsg>) -> bool {
match msg {
AppMsg::Increment => {
self.counter = self.counter.wrapping_add(1);
}
AppMsg::Decrement => {
self.counter = self.counter.wrapping_sub(1);
}
}
true
}
}
#[relm4::widget]
impl Widgets<AppModel, ()> for AppWidgets {
view! {
gtk::ApplicationWindow {
set_title: Some("Simple app"),
set_default_width: 300,
set_default_height: 100,
set_child = Some(>k::Box) {
set_orientation: gtk::Orientation::Vertical,
set_margin_all: 5,
set_spacing: 5,
append = >k::Button {
set_label: "Increment",
connect_clicked(sender) => move |_| {
send!(sender, AppMsg::Increment);
},
},
append = >k::Button {
set_label: "Decrement",
connect_clicked(sender) => move |_| {
send!(sender, AppMsg::Decrement);
},
},
append = >k::Label {
set_margin_all: 5,
set_label: watch! { &format!("Counter: {}", model.counter) },
}
},
}
}
}
fn main() {
let model = AppModel::default();
let app = RelmApp::new(model);
app.run();
}
```
## Projects using Relm4
- [fm](https://github.com/euclio/fm) — A small, general-purpose file manager.
- [Done](https://github.com/edfloreshz/done) - A simple and versatile to do app.
- [Reovim](https://github.com/songww/reovim) - GUI frontend for neovim.
- [NixOS Configuration Editor](https://github.com/vlinkz/nixos-conf-editor) - A graphical configuration editor for [NixOS](https://nixos.org).
## License
Licensed under either of
* Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
* MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
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!**