KAS GUI
=======
[](https://github.com/kas-gui/kas/actions)
[](https://crates.io/crates/kas)
[](https://github.com/kas-gui/kas-text/)
[](https://docs.rs/kas)
Links: [Tutorials](https://kas-gui.github.io/tutorials/) — [Wiki](https://github.com/kas-gui/kas/wiki/Getting-started) — [Examples](examples) — [7GUIs](https://github.com/kas-gui/7guis/) — [Blog](https://kas-gui.github.io/blog/) — [Design](https://github.com/kas-gui/design)
About Kas
---------
The Kas GUI system strives to be both fast and follow Alan Kay's slogan:
> Simple things should be simple, complex things should be possible.
An excerpt from examples/hello.rs:
```rust
let hello_ui = column![
"Hello, world!",
Button::label("&Close").with(|cx, _| cx.exit())
];
```
An excerpt from examples/counter.rs:
```rust
#[derive(Clone, Debug)]
struct Increment(i32);
fn counter() -> impl Widget<Data = ()> {
let tree = column![
format_label!("{}").align(AlignHints::CENTER),
row![
Button::label_msg("−", Increment(-1)),
Button::label_msg("+", Increment(1)),
]
.map_any(),
];
tree.with_state(0)
.on_message(|_, count, Increment(add)| *count += add)
}
```
On the more complex end, custom widgets can be fairly complex; check the Kas
widget library (including source code) for examples.
### Capabilities
- [x] Fully keyboard-accessible
- [x] Screen reader support (partial: kas-gui/kas#509)
- [x] IME support (partial: kas-gui/kas#508)
- [ ] Integrated i18n support (not yet started; kas-gui/kas#7)
- [x] Complex text support: use system fonts with glyph fallbacks, BiDi, common text effects (kas-gui/kas#13)
- [x] Automatic margins and layout with pixel-perfect scaling
- [x] Support for custom themes including theme-driven animations and sizing
- [x] Virtual scrolling (list or grid), including support for async data access
### Goals
Kas is designed to:
- Support stateful user-defined widgets with high-ish level of code
- Support the best user-interaction possible
- Support automatic layout and pixel-perfect scaling at any scale factor (i.e. margins and element sizes should be consistent, raster icons should have pixel-perfect rendering; layout is allowed to change as content is scaled).
- Support extremely fast, monolithic Rust binaries
### Limitations
Every approach has its limitations. Ours are:
- Stateful widgets imply invalid-state bugs are possible. There are some (dev-mode) guards against bad-initialisation order, but fundamentally this class of bugs cannot be prevented.
- Custom widgets have a lot of flexibility over management of child widgets; this comes with some expectations. Violating these expectations will result in a panic in debug builds.
- Custom widget definitions use macro-enhanced Rust (not a custom DSL), allowing the full power of Rust code but running the risk of confusing other tooling (both `rustfmt` and `rust-analyzer` have some issues here).
### Status
In development. Interfaces are not currently stable.
Enough functionality should be present to develop complex GUIs, however some features are still missing (see [the Roadmap](https://github.com/kas-gui/kas/blob/master/ROADMAP.md#future-work).
Crates and features
-------------------
Crates in this repository:
- [kas-core](https://docs.rs/kas-core): the core library
- kas-macros: proc-macro crate (see `kas-core` documentation)
- [kas-widgets](https://docs.rs/kas-widgets): the main widget library
- [kas-view](https://docs.rs/kas-view): view widgets supporting virtual scrolling
- [kas-image](https://docs.rs/kas-image): scalable and raster image widgets and utilities
- [kas-wgpu](https://docs.rs/kas-wgpu): rendering backend over [wgpu]
- [kas-soft](https://docs.rs/kas-soft): basic CPU rendering backend over [softbuffer]
- [kas-dylib](https://crates.io/crates/kas-dylib): helper crate to support dynamic linking
- [kas]: a meta-package plus convenient driver covering most of the above
Significant external dependencies:
- [winit](https://github.com/rust-windowing/winit): platform window integration
- [wgpu](https://github.com/gfx-rs/wgpu): modern accelerated graphics API
- [AccessKit](https://accesskit.dev/): Accessibility infrastructure for UI toolkits
- [kas-text](https://crates.io/crates/kas-text): complex text support
- [rustybuzz](https://crates.io/crates/rustybuzz): a complete harfbuzz's shaping algorithm port to Rust
- [fontique](https://crates.io/crates/fontique): Font enumeration and fallback
- [resvg](https://crates.io/crates/resvg): an SVG rendering library
- [tiny-skia](https://crates.io/crates/tiny-skia): a tiny Skia subset ported to Rust
- [Image](https://crates.io/crates/image): An Image Processing Library
- [impl-tools](https://crates.io/crates/impl-tools): `autoimpl` and `impl_scope` (extensible) macros
- [easy-cast](https://crates.io/crates/easy-cast): Type conversion, success expected
### Feature flags
The `kas` crate enables a selection of important features by default while attempting to support most platforms. Other crates do not enable any features by default.
See [documentation in Cargo.toml](https://github.com/kas-gui/kas/blob/master/Cargo.toml#L29).
[kas]: https://docs.rs/kas
[wgpu]: https://github.com/gfx-rs/wgpu
[softbuffer]: https://github.com/rust-windowing/softbuffer
Copyright and Licence
---------------------
The [COPYRIGHT](COPYRIGHT) file includes a list of contributors who claim
copyright on this project. This list may be incomplete; new contributors may
optionally add themselves to this list.
The KAS library is published under the terms of the Apache License, Version 2.0.
You may obtain a copy of this licence from the [LICENSE](LICENSE) file or on
the following webpage: <https://www.apache.org/licenses/LICENSE-2.0>