4700d33728
See https://zed.dev/channel/gpui-536 Fixes https://github.com/zed-industries/zed/issues/9010 Fixes https://github.com/zed-industries/zed/issues/8883 Fixes https://github.com/zed-industries/zed/issues/8640 Fixes https://github.com/zed-industries/zed/issues/8598 Fixes https://github.com/zed-industries/zed/issues/8579 Fixes https://github.com/zed-industries/zed/issues/8363 Fixes https://github.com/zed-industries/zed/issues/8207 ### Problem After transitioning Zed to GPUI 2, we started noticing that interacting with the mouse on many UI elements would lead to a pretty annoying flicker. The main issue with the old approach was that hover state was calculated based on the previous frame. That is, when computing whether a given element was hovered in the current frame, we would use information about the same element in the previous frame. However, inspecting the previous frame tells us very little about what should be hovered in the current frame, as elements in the current frame may have changed significantly. ### Solution This pull request's main contribution is the introduction of a new `after_layout` phase when redrawing the window. The key idea is that we'll give every element a chance to register a hitbox (see `ElementContext::insert_hitbox`) before painting anything. Then, during the `paint` phase, elements can determine whether they're the topmost and draw their hover state accordingly. We are also removing the ability to give an arbitrary z-index to elements. Instead, we will follow the much simpler painter's algorithm. That is, an element that gets painted after will be drawn on top of an element that got painted earlier. Elements can still escape their current "stacking context" by using the new `ElementContext::defer_draw` method (see `Overlay` for an example). Elements drawn using this method will still be logically considered as being children of their original parent (for keybinding, focus and cache invalidation purposes) but their layout and paint passes will be deferred until the currently-drawn element is done. With these changes we also reworked geometry batching within the `Scene`. The new approach uses an AABB tree to determine geometry occlusion, which allows the GPU to render non-overlapping geometry in parallel. ### Performance Performance is slightly better than on `main` even though this new approach is more correct and we're maintaining an extra data structure (the AABB tree).  Release Notes: - Fixed a bug that was causing popovers to flicker. --------- Co-authored-by: Nathan Sobo <nathan@zed.dev> Co-authored-by: Thorsten <thorsten@zed.dev> |
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Welcome to GPUI!
GPUI is a hybrid immediate and retained mode, GPU accelerated, UI framework for Rust, designed to support a wide variety of applications.
Getting Started
GPUI is still in active development as we work on the Zed code editor and isn't yet on crates.io. You'll also need to use the latest version of stable rust and be on macOS. Add the following to your Cargo.toml:
gpui = { git = "https://github.com/zed-industries/zed" }
Everything in GPUI starts with an App. You can create one with App::new(), and kick off your application by passing a callback to App::run(). Inside this callback, you can create a new window with AppContext::open_window(), and register your first root view. See gpui.rs for a complete example.
The Big Picture
GPUI offers three different registers depending on your needs:
-
State management and communication with Models. Whenever you need to store application state that communicates between different parts of your application, you'll want to use GPUI's models. Models are owned by GPUI and are only accessible through an owned smart pointer similar to an
Rc. See theapp::model_contextmodule for more information. -
High level, declarative UI with Views. All UI in GPUI starts with a View. A view is simply a model that can be rendered, via the
Rendertrait. At the start of each frame, GPUI will call this render method on the root view of a given window. Views build a tree ofelements, lay them out and style them with a tailwind-style API, and then give them to GPUI to turn into pixels. See thedivelement 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
elementmodule 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.
Other Resources
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
actionmodule for more information. -
Platform services, such as
quit the apporopen a URLare available as methods on theapp::AppContext. -
An async executor that is integrated with the platform's event loop. See the
executormodule 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, aTestAppContextwhich provides ways of simulating common platform input. Seeapp::test_contextandtestmodules for more details.
Currently, the best way to learn about these APIs is to read the Zed source code, ask us about it at a fireside hack, 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.