flutter_embedder VS rui

I'm actually working on this as a side project (here).

I personally settled on Flutter. It's a modern declarative UI framework by Google that was designed for mobile apps, but it can also do desktop and web these days. It can be used as a library using its embedder API that can render to Vulkan, Metal and OpenGL. So, it can be embedded in a wgpu context (here's my prototype for that based on wgpu/Vulkan and winit). Flutter uses Dart for UI programming, which is fine for me, since a lot of iteration is necessary for that, and Flutter allows Dart code to be hot reloaded during development (so you just have to save your file and the running application is updated automatically, keeping all of its state intact). Rust wouldn't be able to do that at the moment. Web support is trivial, because Flutter Web allows integrating HTML elements between its UI layers. I can simply insert a canvas there and link that to wgpu.

Here's the repository.

I've started writing my own Flutter shell here that runs on all desktop and mobile systems Flutter supports without any platform-specific code paths. The trick is that I'm delegating the responsibility for platform-specific code to a generic library (winit in this case) and so keep it out of my codebase.

I've started a project for using Rust for a shell using the Flutter Engine's embedder interface, so it’s trivial to integrate Rust into the system. It’s available here.

What I'm currently looking into is using Flutter for UI drawing instead of web tech. It has a built-in compositing API that allows interleaving native drawing with its surfaces and has a Vulkan renderer. The only downside is that you have to write a shell for it that maps the native platform to its APIs, which is very underdocumented and needs a lot of code, for example for handling keyboard input. Here's my progress so far. It comes with shells for all of its supported platforms, but they all use OpenGL or Metal (for iOS/macOS).

I need to check out how well this combines with my Rust-based Flutter shell.

I personally spent a significant part of my spare time in the last few months researching this topic, and came to the conclusion that for my (very similar) project, I'd like to use Flutter and Dart for the UI and Rust with wgpu (maybe bevy) for the rendering backend. I'm working on an integration for native platforms (so everything except web) right now, it's available in earliest alpha here. Web itself is trivial, because you can simply mount a separate canvas as a platformview and use that for wgpu, completely separating the two worlds.

Unfortunately, I'm really busy these days so I don't have any time for any more projects. I'm currently working on this project, which allows using the UI framework Flutter together with wgpu, so I'd say that it's adjacent to your project.

Inspired by Xilem, Leptos and rui, Floem aims to be a high performance declarative UI library with minimal effort from the user.

My rui library can render UIs at 120fps, uses similar SDF techniques (though uses a single shader for all rendering): https://github.com/audulus/rui

Is their GPUI library open source?

I think the jury is still out on whether rust is good or bad for UI. Once rust UI libraries are more mature we'll get a sense of it. There are some advantages of static typing, even for UI (see SwiftUI for example). I'll grant the pickiness of rust can be a challenge. Anyway give us some time to work on stuff.

Here's my effort: https://github.com/audulus/rui

rui

Depending on the scale of your project, I could suggest rui library which is cross platform though it's not related to gtk, https://github.com/audulus/rui, It's inspired by swiftUI

I've done a library for vector graphics on the GPU which works pretty well for my uses:

https://github.com/audulus/vger

and a rust version:

https://github.com/audulus/vger-rs

(which powers my rust GUI library: https://github.com/audulus/rui)

Here's the approach for rendering path fills. From the readme:

> The bezier path fill case is somewhat original. To avoid having to solve quadratic equations (which has numerical issues), the fragment function uses a sort-of reverse Loop-Blinn. To determine if a point is inside or outside, vger tests against the lines formed between the endpoints of each bezier curve, flipping inside/outside for each intersection with a +x ray from the point. Then vger tests the point against the area between the bezier segment and the line, flipping inside/outside again if inside. This avoids the pre-computation of Loop-Blinn, and the AA issues of Kokojima.

It works pretty well, and doesn't require as much preprocessing as the code in the article. Also doesn't require any GPU compute (though I do use GPU compute for some things). I think ultimately the approach in the article (essentially Piet-metal, aka tessellating and binning into tiles) will deliver better performance, and support more primitives, but at greater implementation complexity. I've tried the Piet-metal approach myself and it's tricky! I like the simpler Shadertoy/SDF inspired approach :)

You should look into rui, https://github.com/audulus/rui It is an amazing ui Library for rust

Try rui https://github.com/audulus/rui, It's a Swift Type ui