The Orbital Widget Toolkit is a cross-platform (G)UI toolkit for building scalable user interfaces with the programming language Rust. It's based on the Entity Component System Pattern and provides a functional Reactive-like API.

The main goals of OrbTk are speed, ease of use, and cross-platform compatibility.

Features:

• Modern lightweight API
• Cross platform
• Modular crates
• Based on Entity Component System library DCES
• Flexible event system
• Integrated widget library
• Custom widgets
• Custom theming engine
• Dynamic theme switching
• Integrated debugging tools

Platforms

• Redox OS (native)
• Linux (native | cargo-node)
• macOS (native | cargo-node)
• Windows (native | cargo-node)
• openBSD (not tested, but should work)
• Web (cargo-node)
• Android (native planned | cargo-node)
• iOS (native planned | cargo-node planned)
• Ubuntu Touch (native planned | cargo-node planned)

Planned features

• Conformable use of async
• More default widgets
• Book
• Animations
• Split application in modules
• 3D context
• More integrated debugging tools

Usage

To include OrbTk in your project, add this dependency line to your Cargo.toml file:

orbtk = "0.3.1-alpha2"

To use the latest development version of OrbTk, add this dependency line to your Cargo.toml file:

orbtk = { git = "https://github.com/redox-os/orbtk.git", branch = "develop" }

You can also check out the OrbTk template project to start a new project: https://github.com/redox-os/orbtk-template.

Minimal Example

use orbtk::prelude::*;

fn main() {
      Application::new()
        .window(|ctx| {
            Window::new()
                .title("OrbTk - minimal example")
                .position((100.0, 100.0))
                .size(420.0, 730.0)
                .child(TextBlock::new().text("OrbTk").build(ctx))
                .build(ctx)
        })
        .run();
}

Base concepts

Widget

Widgets are the building blocks of user interfaces in OrbTk. They are things like Buttons, TextBoxes, ListViews, Views (Screens) and Grid(Layout)s. Each widget implements the Widget trait and is generated by the widget! macro. A widget consists of a name like Button and a list of its properties like text: String16, background: Brush or count: u32. After the build method of a widget is called it's added to the Entity Component System where it exists as an Entity (index) with Components. The struct of a widget serves as a builder using the builder pattern.

Basic usage of the widget! macro:

widget!(
    MyWidget {
      background: Brush,
      count: u32,
      text: String16,
      ...
    }
);

Widget Templates

Each widget has to implement the Template trait. The template defines the default values of a widget's properties as well as its structure. A Button e.g. consists of a Container widget, a StackPanel widget and a TextBlock widget.

Basic usage of the Template trait:

impl Template for MyWidget {
    fn template(self, id: Entity, ctx: &mut BuildContext) -> Self {
         self.name("MyWidget")
            .style("my_widget_style")
            .background("#000000")
            .count(0)
            .text("Initial text")
            .child(Container::new()
                    // Container references the same background as MyWidget
                    .background(id)
                    .child(TextBlock::new()
                            // TextBlock references the same text as MyWidget
                            .text(id)
                            .build(ctx)
                    )
                    .build(ctx)
            )
    }
}

Widget State

The state of a widget is used to update its inner state. Each state has to implement the State trait. The inner state of a widget is represented by the current values of its properties.

Basic usage of the state trait:

#[derive(Default, AsAny)]
struct MyState {
    ...
}

impl State for MyState {
    fn update(&mut self, _: &mut Registry, ctx: &mut Context) {
        // update the widget
        ...
    }
}

widget!(
    // Add MyState as state of MyWidget
    MyWidget<MyState> {
        ...
    }
);

The Context parameter of the update method provides access to the state's widget (entity) and its properties (components). It also provides functions to access the children of the widget, and to manipulate the widget tree.

Styling widgets and define themes

OrbTk provides a theme engine base on RON. The engine provides the following features:

• Split theme in different files
• Outsource resources like colors and font stuff
• Derive styles
• Dynamic theme switch
• State styling (pressed | selected | focused | disabled)

Short example:

Theme (
    styles: {
        "base": (
            properties: {
                "font_size": "$FONT_SIZE_12",
                "font_family": "$MEDIUM_FONT",
            }
        ),
        "button": (
            base: "base",
            properties: {
                "background": "$BLACK",
            },
            states: {
                "pressed": {
                    "background": "$WHITE",
                }
            }
        )
    },
    resource: {
        "BLACK": "#000000",
        "WHITE": "#ffffff",
        "MEDIUM_FONT": "Roboto-Medium",
        "FONT_SIZE_12": 12,
        "FONT_SIZE_16": 16,
    }
)

OrbTk will also provide a plain mechanism to style and theme widgets and UIs.

Run Examples

On Linux you first need to install

sudo apt install libxkbcommon-dev libwayland-cursor0 libwayland-dev

You can find examples in the examples/ directory.

You can start the widgets example by executing the following command:

cargo run --example widgets --release

OrbTk has integrated debug tools. If you want to show the bounds of all widgets (even invisible ones) and want to see a debug print of the whole widget tree, you can run the examples with --features debug, like this:

cargo run --example widgets --release --features debug

Run Examples with cargo-node

To run the examples as a browser, electron or cordova app you have to install cargo-node:

cargo install -f cargo-node

Before you can use cargo-node you have to install npm version 6.9.0, which is included with Node.js version 10.16.3. You can download it from https://nodejs.org/dist/v10.16.3/.

Rust's cargo is also required. The rest of cargo-node's dependencies are installed automatically.

Start examples

You can run the "widgets" example by executing one of the following commands:

• Run as browser app:

cargo node run --target browser --example widgets

• Run as electron app:

cargo node run --target electron --example widgets

• Run as cordova app on android:

cargo node run --target android --example widgets

Documentation

Build and open documentation

You can build and view the latest documentation by executing the following command:

cargo doc --no-deps --open

OrbTk Manual

To build and run the latest version of the OrbTk manual check: Manual

Sub Crates

• api: base api elements of OrbTk e.g. widget and application parts
• proc-macros: procedural helper macros
• render: cross platform 2D/3D render library
• shell: cross platform window and event handling
• theming: provide mechanism to style OrbTk UI's in rust and ron (replaces css-engine)
• tree: tree structure based on DCES
• utils: helper structs and traits
• widgets: base widget library

Inspirations

• Flutter
• React
• Yew

Showcases

• Space Editor: 2D Tile Map Editor compatible with OrbGame
• doit: Task app
• OrbCalculator: Calculator based on OrbTk
• Kanter: Node based texture editor
• twin-commander: A twin-panel file manager specifically for the Redox OS

Contribution

If you want to help improve OrbTk you submit your feedback in the issue tracker, or make a pull request to fix an issue https://github.com/redox-os/orbtk/issues. You can also discuss OrbTk with us on the Redox chat https://redox-os.org/community/ (join the OrbTk channel).

Contribution check list

• Documentation for all pub structs, traits and funs
• Add tests if needed
• Use static &str for widget ids and new style definitions
• For widget development check ProgressBar or Slider as example
• Add changes to changelog
• Expand examples or create a new one if needed
• cargo fmt add the end
• Create PR

License

Licensed under MIT license (LICENSE).