= Relm
Asynchronous, GTK+-based, GUI library, inspired by Elm, written in Rust.
*This library is in alpha stage: it has not been thoroughly tested and its API may change at any time.*
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== Requirements
Since relm is based on GTK+, you need this library on your system in order to use it.
See http://gtk-rs.org/docs/requirements.html[this page] for information on how to install GTK+.
== Usage
First, add this to your `Cargo.toml`:
[source,toml]
----
gtk = "^0.8.0"
relm = "^0.19.0"
relm-derive = "^0.19.0"
----
Next, add this to your crate:
[source,rust]
----
use relm::{Relm, Update, Widget};
use gtk::prelude::*;
use gtk::{Window, Inhibit, WindowType};
use relm_derive::Msg;
----
Then, create your model:
[source,rust]
----
struct Model {
// …
}
----
The model contains the data related to a `Widget`. It may be updated by the `Widget::update` function.
Create your message `enum`:
[source,rust]
----
#[derive(Msg)]
enum Msg {
// …
Quit,
}
----
Messages are sent to `Widget::update` to indicate that an event happened. The model can be updated when an event is received.
Create a `struct` which represents a `Widget` which contains the GTK+ widgets (in this case, the main window of the application) and the model:
[source,rust]
----
struct Win {
// …
model: Model,
window: Window,
}
----
To make this `struct` a relm `Widget` that can be shown by the library, implement the `Update` and `Widget` traits:
[source,rust]
----
impl Update for Win {
// Specify the model used for this widget.
type Model = Model;
// Specify the model parameter used to init the model.
type ModelParam = ();
// Specify the type of the messages sent to the update function.
type Msg = Msg;
// Return the initial model.
fn model(_: &Relm<Self>, _: ()) -> Model {
Model {
}
}
// The model may be updated when a message is received.
// Widgets may also be updated in this function.
fn update(&mut self, event: Msg) {
match event {
Msg::Quit => gtk::main_quit(),
}
}
}
impl Widget for Win {
// Specify the type of the root widget.
type Root = Window;
// Return the root widget.
fn root(&self) -> Self::Root {
self.window.clone()
}
// Create the widgets.
fn view(relm: &Relm<Self>, model: Self::Model) -> Self {
// GTK+ widgets are used normally within a `Widget`.
let window = Window::new(WindowType::Toplevel);
// Connect the signal `delete_event` to send the `Quit` message.
connect!(relm, window, connect_delete_event(_, _), return (Some(Msg::Quit), Inhibit(false)));
// There is also a `connect!()` macro for GTK+ events that do not need a
// value to be returned in the callback.
window.show_all();
Win {
model,
window,
}
}
}
----
Finally, show this `Widget` by calling `Win::run()`:
[source,rust]
----
fn main() {
Win::run(()).unwrap();
}
----
=== `#[widget]` attribute
A `#[widget]` attribute is provided to simplify the creation of a widget.
This attribute does the following:
* Provide a `view!` macro to create the widget with a declarative syntax.
* Automatically create the `fn root()`, `type Msg`, `type Model`, `type ModelParam` and `type Root` items.
* Automatically insert the call to `Widget::set_property()` in the `update()` function when assigning to an attribute of the model.
* Automatically create the `Widget` `struct`.
* `Update` and `Widget` traits can be implemented at once.
To use this attribute, add the following code:
[source,rust]
----
use relm_derive::widget;
----
Here is an example using this attribute:
[source,rust]
----
#[derive(Msg)]
pub enum Msg {
Decrement,
Increment,
Quit,
}
pub struct Model {
counter: u32,
}
#[widget]
impl Widget for Win {
fn model() -> Model {
Model {
counter: 0,
}
}
fn update(&mut self, event: Msg) {
match event {
// A call to self.label1.set_text() is automatically inserted by the
// attribute every time the model.counter attribute is updated.
Msg::Decrement => self.model.counter -= 1,
Msg::Increment => self.model.counter += 1,
Msg::Quit => gtk::main_quit(),
}
}
view! {
gtk::Window {
gtk::Box {
orientation: Vertical,
gtk::Button {
// By default, an event with one paramater is assumed.
clicked => Msg::Increment,
// Hence, the previous line is equivalent to:
// clicked(_) => Increment,
label: "+",
},
gtk::Label {
// Bind the text property of this Label to the counter attribute
// of the model.
// Every time the counter attribute is updated, the text property
// will be updated too.
text: &self.model.counter.to_string(),
},
gtk::Button {
clicked => Msg::Decrement,
label: "-",
},
},
// Use a tuple when you want to both send a message and return a value to
// the GTK+ callback.
delete_event(_, _) => (Msg::Quit, Inhibit(false)),
}
}
}
----
NOTE: The `struct Win` is now automatically created by the attribute, as are the function `root()` and the associated types `Model`, `ModelParam`, `Msg` and `Container`.
You can still provide the method and the associated types if needed, but you cannot create the `struct`.
WARNING: The `#[widget]` makes the generated `struct` public: hence, the corresponding model and message types must be public too.
[WARNING]
====
Your program might be slower when using this attribute because the code generation is simple.
For instance, the following code
[source,rust]
----
fn update(&mut self, event: Msg) {
for _ in 0..100 {
self.model.counter += 1;
}
}
----
will generate this function:
[source,rust]
----
fn update(&mut self, event: Msg) {
for _ in 0..100 {
self.model.counter += 1;
self.label1.set_text(&self.model.counter.to_string());
}
}
----
====
[WARNING]
====
Also, the `set_property()` calls are currently only inserted when assigning to an attribute of the model.
For instance, the following code
[source,rust]
----
fn update(&mut self, event: Msg) {
self.model.text.push_str("Text");
}
----
will not work as expected.
Please use the following variation if needed.
[source,rust]
----
fn update(&mut self, event: Msg) {
self.model.text += "Text";
}
----
====
For more information about how you can use relm, you can take a look at the https://github.com/antoyo/relm/tree/master/relm-examples/[examples].
== Donations
If you appreciate this project and want new features to be
implemented, please support me on Patreon.
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== Projects using `relm`
* https://github.com/sanpii/yellow-pitaya[Yellow Pitaya]
* https://github.com/juchiast/gameoflife[Game of Life]
* https://github.com/sebasmagri/rusty-sounds[Rusty Sounds]
* https://github.com/etrombly/country_parser[Country Parser]
* https://github.com/niklasf/rust-chessground[Chessground]
* https://github.com/sanpii/effitask[Effitask]
* https://github.com/knack-supply/curve-tracer[KS Curve Tracer]
* https://github.com/emmanueltouzery/cigale[Cigale]
If you want to add your project to this list, please https://github.com/antoyo/relm/pulls[create a pull request].