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# Floem

A native Rust UI library with fine-grained reactivity

[![crates.io](https://img.shields.io/crates/v/floem.svg)](https://crates.io/crates/floem)
[![docs.rs](https://docs.rs/floem/badge.svg)](https://docs.rs/floem)
[![Discord](https://img.shields.io/discord/946858761413328946?color=%237289DA&label=discord)](https://discord.gg/RB6cRYerXX)

</div>

_The project is still maturing. We will make occasional breaking changes and add missing features on our way to v1._

## Quickstart

![Quickstart](docs/img/quickstart.png)

```rust
use floem::reactive::create_signal;
use floem::view::View;
use floem::views::{h_stack, label, v_stack, Decorators};
use floem::widgets::button;

fn app_view() -> impl View {
    // Create a reactive signal with a counter value, defaulting to 0
    let (counter, set_counter) = create_signal(0);

    // Create a vertical layout
    v_stack((
        // The counter value updates automatically, thanks to reactivity
        label(move || format!("Value: {}", counter.get())),
        // Create a horizontal layout
        h_stack((
            button(|| "Increment").on_click_stop(move |_| {
                set_counter.update(|value| *value += 1);
            }),
            button(|| "Decrement").on_click_stop(move |_| {
                set_counter.update(|value| *value -= 1);
            }),
        )),
    ))
}

fn main() {
    floem::launch(app_view);
}
```

## Features

Inspired by [Xilem](https://github.com/linebender/xilem), [Leptos](https://github.com/leptos-rs/leptos) and [rui](https://github.com/audulus/rui), Floem aims to be a high performance declarative UI library requiring minimal user effort.

- **Cross-platform support**: Supports Windows, macOS and Linux with rendering using [Wgpu](https://github.com/gfx-rs/wgpu). In case a GPU is unavailable, a CPU renderer powered by [tiny-skia](https://github.com/RazrFalcon/tiny-skia) will be used.
- **Fine-grained reactivity**: The entire library is built around reactive primitives inspired by [leptos_reactive](https://crates.io/crates/leptos_reactive). The reactive "signals" allow you to keep your UI up-to-date with minimal effort, all while maintaining very high performance.
- **Performance**: The view tree is only run once, safeguarding you from accidentally create a bottleneck in a view generation function that slows down your entire application. Floem also provides tools to help you write efficient UI code, such as a [virtual list](https://github.com/lapce/floem/tree/main/examples/virtual_list).
- **Flexbox layout**: Using [taffy](https://crates.io/crates/taffy), the library provides the Flexbox (or Grid) layout system, which can be applied to any View node.
- **Customizable widgets**: Don't want the default look? You can change pretty much anything you want using the styling API, or install a third-party theme.
- **Element inspector**: Inspired by your browser's developer tools, Floem provides a [diagnostic tool](https://lapce.dev/floem/floem/id/struct.Id.html#method.inspect) to debug your layout.

To sample Floem's capabilities, check out the repo and run the [widget gallery](examples/widget-gallery/src/main.rs) example with cargo.

![Widget gallery](docs/img/widget-gallery.png)

To help you master Floem, we provide [documentation](https://docs.rs/floem) and [code examples](examples/).

## Contributions

[Contributions welcome!](CONTRIBUTING.md) If you'd like to improve how Floem works and fix things, feel free to open an issue or submit a PR. If you'd like a conversation with Floem devs, you can join in the #floem channel on this [Discord](https://discord.gg/RB6cRYerXX).