KAS GUI

KAS, (historically the toolKit Abstraction System), is a general-purpose GUI toolkit. KAS's design provides:

• retained mode (library stores state), inspired by Qt (classic)
• concise, partially declarative specification of widgets
• type-safe, widget-local event handlers
• simple ownership with no retained pointers into widget state
• fast, efficient, responsive UI

Documentation

• API docs: https://docs.rs/kas, https://docs.rs/kas-theme, https://docs.rs/kas-wgpu
• KAS Tutorials
• Examples
• Discuss
• KAS Blog

Examples

Examples can be found in kas-wgpu/examples/. Further examples can be found in kas-gui/7guis.

Precompiled example apps can be downloaded as follows:

• go to https://github.com/kas-gui/kas/actions/workflows/build.yml
• select the latest (complete) run
• download one of the examples-* artifacts

Features

The below should give a rough idea of what's done and what's not. See also the ROADMAP.

• Stepless DPI scaling
• Texts supporting bidirectional languages and font fallback
• Accelerated graphics via WebGPU (via DirectX/Vulkan/Metal or possibly OpenGL); currently no CPU fallback
• Shaders in custom widgets (see Mandlebrot example)
• Support themes, colour schemes and end-user configuration
• Keyboard navigation and control
• View widgets over shared state

Installation and dependencies

Rust

KAS requires [Rust] version 1.52 or greater (currently in beta: usually we maintain compatibility with the latest stable release). Using the nightly channel does have a couple of advantages:

• Proceedural macros emit better diagnostics. In some cases, diagnostics are missed without nightly rustc, hence nightly is recommended for development.
• Documentation generated via cargo doc requires nightly for links
• A few minor option things: see Feature flags below.

Quick-start

Install dependencies:

# For Ubuntu:
sudo apt-get install build-essential git libxcb-shape0-dev libxcb-xfixes0-dev libharfbuzz-dev

# For Fedora:
# glslc is optional; see kas-wgpu/README.md
sudo dnf install libxcb-devel harfbuzz-devel glslc

Next, clone the repository and run the examples as follows:

git clone https://github.com/kas-gui/kas.git
cd kas
cargo test
cd kas-wgpu
cargo build --examples
cargo run --example gallery
cargo run --example layout
cargo run --example mandlebrot

If possible, wgpu (WebGPU) will use the Vulkan, Metal or DirectX 12 graphics API. If none of these are available it may instead use OpenGL, however this currently requires the wgpu/cross feature:

cargo run --example gallery --features wgpu/cross

(To force OpenGL on other platforms, set KAS_BACKENDS=GL.)

To build docs locally:

RUSTDOCFLAGS="--cfg doc_cfg" cargo +nightly doc --features markdown --no-deps --all --open

Crates

• kas: the core of the GUI library, providing most interfaces and logic along with a selection of common widgets
• kas-macros: a helper crate for proc macros (do not use directly)
• KAS-text: font loading, text layout, text navigation
• kas-theme: theming support for KAS (API plus two themes; organisation may change)
• kas-wgpu: provides windowing via winit and rendering via WebGPU

A user depends on kas to write their complete UI specification, selects a theme from kas-theme, instances a kas_wgpu::Toolkit, adds the window(s), and runs the UI.

Feature flags

The kas crate has the following feature flags:

• markdown: enables Markdown parsing for rich-text
• config: adds (de)serialisation support for configuration plus a few utility types (specifying serde instead only implements for utility types)
• json: adds config (de)serialisation using JSON (implies config)
• yaml: adds config (de)serialisation using YAML (implies config)
• ron: adds config (de)serialisation using RON (implies config)
• svg: adds support for SVG images
• winit: adds compatibility code for winit's event and geometry types. This is currently the only functional windowing/event library.
• stack_dst: some compatibility impls (see kas-theme's documentation)
• internal_doc: turns on some extra documentation intended for internal usage but not for end users. (This only affects generated documentation.)

Additionally, the following flags require a nightly compiler:

• nightly: enables "more stable" unstable features
• min_spec (enabled by nightly): use min_specialization to draw underlines in AccelLabel
• spec: use specialization to enable TryFormat
• gat: compatibility with kas-text/gat

Configuration

Formats are not yet stabilised, hence reading/writing configuration is disabled by default. Ensure that the yaml and/or json feature flag is enabled, then configure with environment variables:

# Set the config path:
export KAS_CONFIG=kas-config.yaml
# Use write-mode to write out default config:
KAS_CONFIG_MODE=writedefault cargo run --example gallery
# Now just edit the config and run like normal:
cargo run --example gallery

Copyright and Licence

The 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 file or on the following webpage: https://www.apache.org/licenses/LICENSE-2.0