Thorsten Ball
82435075a5
This reverts commit f69c8ca74e after it
has already been partially reverted in
https://github.com/zed-industries/zed/pull/13458.
Why the revert?
The changes in that commit/PR fix one type of problem — dropping of
frames when being blasted with input events — but trades it for another
one that I can't explain yet: when the system is under load, then input
becomes _laggy_ and input events seem to be delayed.
Two examples of how that shows up:
1. When the system is under load* and you hold down the `down` key to
scroll, then lift the finger, the cursor stops sometimes. If you then
produce another input event by jiggling the mouse cursor you'll see more
`down`-key events coming up and the cursor moving down. It feels as if
the event loop is not being woken up even though there are still events.
I suspect it might have something to do with XIM, because if it's
disabled, it seems as if problems become less severe.
2. When the system is under load* and you click-and-drag a selection in
the editor, you can see how the selection is delayed and takes 500ms-1s
to catch up to where the cursor is.
* system under load: start Zed, then in another terminal window create a
release build of Zed, for example.
With the changes reverted, the failure mode looks different: we skip
frames. But that, I think, is the better of two bad options, because
skipping frames means that you see what's happening vs. input events
seemingly still coming in seconds after you stopped using the keyboard.
Release Notes:
- N/A
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.