LGUI

lgui is an application-independent Rust GUI library. An application supplies one root component, chooses a platform backend, and starts it with Application::with_backend(...); lgui owns the component session, retained host tree, event dispatch, reactive updates, windows, renderer, and frame submission.

The portable core provides typed component State, committed Effects, Commands, Events, Context, layout, input, and scene construction. Separate add-on crates provide Store, Router, themes, and widgets. Optional features compose those packages with the Win32 or winit platform backend, GDI, Direct2D, or Skia rendering, images, SVG, desktop services, diagnostics, and Tokio execution.

Application resources are ordinary typed data. Asset resolvers and custom paint providers are provided to Application, while renderers own their native caches and device resources. Business crates do not create a second runtime, dispatcher, presenter, WndProc, or window registry.

Commands and Events are typed, Application-scoped capabilities. Commands use receiver-free invoke::<C>(args).await; Events use a stable EventKey<T> with emit(key, payload).await, listen(key, listener), and listen_async(key, listener). Neither path requires serialization, IPC, or a Store dependency. Applications define the concrete contracts and register service-backed command handlers.

fn app(cx: &mut RenderCx<'_, '_>) -> Element {
    let count = cx.state(0_i32);
    let increment = count.clone();

    stack(UiRect::new(0.0, 0.0, 360.0, 200.0), Axis::Vertical)
        .content((
            text(UiRect::new(0.0, 0.0, 312.0, 56.0), format!("{}", count.get()), TextStyle::default()),
            button(
                UiRect::new(0.0, 0.0, 312.0, 48.0),
                "one up",
                ButtonStyle::default(),
            )
                .on_click(move |_| increment.update(|value| *value += 1)),
        ))
        .into()
}

Application::with_backend(WinitApplication::new(GraphicsPreference::Auto))
    .provide(RendererKind::Skia(GraphicsPreference::Auto))
    .memory_options(MemoryOptions::unbounded(
        ImageCachePolicy::WhileVisible,
        false,
    ))
    .window_options(WindowOptions::new("counter").size(Size::new(380.0, 240.0)))
    .run(app)?;

The workspace publishes fifteen packages with one owner for each responsibility:

Package	Responsibility
`lgui`	Application-facing facade and feature composition
`lgui-core`	Portable application runtime, components, layout, input, Scene, windows, and memory governance
`lgui-assets`	Image loading and caching, render resources, custom paint providers, and SVG icons
`lgui-diagnostics`	Frame samples, renderer metrics, collectors, and diagnostics providers
`lgui-services`	Clipboard, dialogs, URL opening, notifications, and tray contracts and adapters
`lgui-router`	Route history, matching, declarative routes, outlets, and navigation hooks
`lgui-store`	Application-scoped stores, selectors, actions, and subscriptions
`lgui-widgets`	Theme tokens and reusable controls
`lgui-render-api`	Frame, damage, renderer lifecycle, and memory-pressure contracts
`lgui-render-skia`	Skia scene painting, text layout, software surface, and renderer caches
`lgui-render-gdi`	Native GDI renderer and optional retained GDI pipeline
`lgui-render-d2d`	Direct2D, D3D11, DXGI, and DirectComposition renderer
`lgui-platform-winit`	Portable desktop windows, input, event loop, and Skia surfaces
`lgui-platform-win32`	Native Win32 windows, message dispatch, system services, renderer host contract, and native pixel interop

Applications should normally depend only on lgui; the other packages are public so renderer and platform integrations can be developed and released independently.

See ARCHITECTURE.md, API.md, BASELINE.md, and the implementation/status contract in SKIA_DESIGN.md. Build the portable core with:

cargo test -p lgui-core --no-default-features

Add the Windows-native default configuration to an application with:

[dependencies]
lgui = "0.2.0"

For the portable winit + Skia backend, disable the Windows-oriented defaults and select a Skia presentation feature explicitly:

[dependencies]
lgui = { version = "0.2.0", default-features = false, features = ["renderer-skia-gl", "widgets"] }

Run the same example source through the portable winit + Skia backend on Windows, Linux, or macOS:

cargo run --example counter --no-default-features --features renderer-skia-gl,widgets

The Skia desktop backend uses winit with Vulkan, OpenGL, Metal, or software presentation. Applications on macOS may enable renderer-skia-metal; Linux and Windows applications may enable their platform-specific Vulkan feature. Explicit GPU choices return an error when the requested driver is unavailable; only Auto follows the bounded fallback chain.

License

LGUI is licensed under either the Apache License, Version 2.0 or the MIT License, at your option.

lgui 0.2.0

LGUI

License