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: ```sh

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: sh 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: sh 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.)
• macros_log: enable logging in macro-generated code. Requires that all crates using derive(Widget) or make_widget depend on the log crate.

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: ```sh

Set the config path:

export KAS_CONFIG=kas-config.yaml

Use write-mode to write out default config:

KASCONFIGMODE=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