GPUI is a hybrid immediate and retained mode, GPU accelerated, UI framework for Rust, designed to support a wide variety of applications.
GPUI is still in active development as we work on the Zed code editor, and is still pre-1.0. There will often be breaking changes between versions. You'll also need to use the latest version of stable Rust and be on macOS or Linux. Add the following to your Cargo.toml:
gpui = { version = "*" }
Everything in GPUI starts with an Application. You can create one with Application::new(), and kick off your application by passing a callback to Application::run(). Inside this callback, you can create a new window with App::open_window(), and register your first root view. See gpui.rs for a complete example.
GPUI has various system dependencies that it needs in order to work.
On macOS, GPUI uses Metal for rendering. In order to use Metal, you need to do the following:
Ensure you launch Xcode after installing, and install the macOS components, which is the default option.
sh
xcode-select --install
sh
sudo xcode-select --switch /Applications/Xcode.app/Contents/Developer
GPUI offers three different registers depending on your needs:
State management and communication with Entity's. Whenever you need to store application state that communicates between different parts of your application, you'll want to use GPUI's entities. Entities are owned by GPUI and are only accessible through an owned smart pointer similar to an Rc. See the app::context module for more information.
High level, declarative UI with views. All UI in GPUI starts with a view. A view is simply an Entity that can be rendered, by implementing the Render trait. At the start of each frame, GPUI will call this render method on the root view of a given window. Views build a tree of elements, lay them out and style them with a tailwind-style API, and then give them to GPUI to turn into pixels. See the div element for an all purpose swiss-army knife of rendering.
Low level, imperative UI with Elements. Elements are the building blocks of UI in GPUI, and they provide a nice wrapper around an imperative API that provides as much flexibility and control as you need. Elements have total control over how they and their child elements are rendered and can be used for making efficient views into large lists, implement custom layouting for a code editor, and anything else you can think of. See the element module for more information.
Each of these registers has one or more corresponding contexts that can be accessed from all GPUI services. This context is your main interface to GPUI, and is used extensively throughout the framework.
GPUI keeps native app hosts separate from the Rust platform crates. The current
iOS host shell lives in hosts/ios, and cargo gpui is the canonical
interface for syncing and running it.
cargo gpui host sync ios
cargo gpui devices ios
cargo gpui run ios
cargo gpui run ios hello_world --sim
The host-shell model is documented in hosts/README.md.
In addition to the systems above, GPUI provides a range of smaller services that are useful for building complex applications:
Actions are user-defined structs that are used for converting keystrokes into logical operations in your UI. Use this for implementing keyboard shortcuts, such as cmd-q. See the action module for more information.
Platform services, such as quit the app or open a URL are available as methods on the app::App.
An async executor that is integrated with the platform's event loop. See the executor module for more information.,
The [gpui::test] macro provides a convenient way to write tests for your GPUI applications. Tests also have their own kind of context, a TestAppContext which provides ways of simulating common platform input. See app::test_context and test modules for more details.
Currently, the best way to learn about these APIs is to read the Zed source code or drop a question in the Zed Discord. We're working on improving the documentation, creating more examples, and will be publishing more guides to GPUI on our blog.