wpt VS Azul

To reply mostly with my WPT Core Team hat off, mostly summarising the history of how we've ended up here:

A build script used by significant swaths of the test suite is almost certainly out; it turns out people like being able to edit the tests they're actually running. (We _do_ have some build scripts — but they're mostly just mechanically generating lots of similar tests.

A lot of the goal of WPT (and the HTML Test Suite, which it effectively grew out of) has been to have a test suite that browsers are actually running in CI: historically, most standards test suites haven't been particularly amenable to automation (often a lot of, or exclusively, manual tests, little concern for flakiness, etc.), and with a lot of policy choices that effectively made browser vendors choose to write tests for themselves and not add new tests to the shared test suite: if you make it notably harder to write tests for the shared test suite, most engineers at a given vendor are simply going to not bother.

As such, there's a lot of hesitancy towards anything that regresses the developer experience for browser engineers (and realistically, browser engineers, by virtue of sheer number, are the ones who are writing the most tests for web technologies).

That said, there are probably ways we could make things better: a decent number of tests for things like Grid use check-layout-th.js (e.g., https://github.com/web-platform-tests/wpt/blob/f763dd7d7b7ed...).

One could definitely imagine a world in which these are a test type of their own, and the test logic (in check-layout-th.js) can be rewritten in a custom test harness to do the same comparisons in an implementation without any JS support.

The other challenge for things like Taffy only targeting flexbox and grid is we're unlikely to add any easy way to distinguish tests which are testing interactions with other layout features (`position: absolute` comes to mind!).

My suggestion would probably be to start with an issue at https://github.com/web-platform-tests/rfcs/issues, describing the rough constraints, and potentially with one or two possible solutions.

It also helps that there are tests

https://web-platform-tests.org/

You can see how Mozilla tests the compliance of their built-in elements in the Gecko repository (the ok and is assertions are defined in their SimpleTest testing framework). And here's the Web Platform Tests' reflection harness, with data for each built-in element in sibling files, that almost every browser pass.

We have our own test suite (orginally derived from the test suite of Meta's Yoga layout library [0]) which consists of text fixtures that are small HTML snippets [1] and a test harness [2] that turns those into runnable tests, utilising headless chrome both to parse the HTML and to generate the assertions based on the layout that Chrome renders (so we are effectively comparing our implementation against Chrome). We currently have 686 generated tests (covering both Flexbox and CSS Grid).

We would like to utilise the Web Platform Test suite [3], however these are not in a standard format and many of the tests require JavaScript so we are not currently able to do that.

[0]: https://github.com/facebook/yoga

[1]: https://github.com/DioxusLabs/taffy/tree/main/test_fixtures

[2]: https://github.com/DioxusLabs/taffy/tree/main/scripts/gentes...

[3]: https://github.com/web-platform-tests/wpt/tree/master/css/cs...

The metrics are based on the passing rate for the web-platform-tests (WPT) project, the automated test suite for web standards. The completion rate is categorised as either stable, or experimental. There is no definition of what experimental entails, presumably features that are behind experimental flags are included. Stable is better to go off in any case.

Depends on what you are trying to achieve. You can run WPT MSE https://github.com/web-platform-tests/wpt/tree/master/media-source and WebCodecs https://github.com/web-platform-tests/wpt/tree/master/webcodecs tests manually to learn by doing.

Manually running the tests in Web Platform Tests should keep you busy.

Not sure what you mean? I referred to Web API's, which generally means Web platform API's; that is Web platform API's tested by Web Platform Tests https://github.com/web-platform-tests/wpt.

If you want CSS to be the same across browsers then help implement CSS tests and file bugs

https://www.w3.org/Style/CSS/Test/Overview.en.html

https://web-platform-tests.org/

better specs are great, but tests will actually find the edge cases and lead to more convergence.

Run all these tests locally https://github.com/web-platform-tests/wpt/tree/master/dom.

Not sure what you mean but WebRender powers Firefox which definitely works on the desktop.

You can use it to build desktop UI frameworks - see for example https://azul.rs/

I'd been wanting to see this, preferably with JS being optional, and just allowing direct DOM access.

I initially thought this was what Azul was, but it's only just using Servo's WebRender compositor, and rolls its own CSS parser, DOM, and layout engine, so it doesn't benefit from most of the work done on Servo, and supports less CSS features.

https://github.com/fschutt/azul

Both Servo and Fifefox make use of webrender, which is an awesome piece of tech and is well suited to render a web page. Some GUI projects attempted to use webrender directly as well, like Azul and moxie-native

> But no one is saying, "Hey I have a CSS 2.1 compliant rasterizer and compositor that you can use in your C++ or Rust environment!" are they?

There’s actually quite a lot of interesting work going on in that general space, has been in various forms for some years. A couple that immediately spring to mind:

• Azul <https://azul.rs/> builds on WebRender, as used in Firefox. I haven’t looked at it for a few years, but it looks to have grown quite interesting now.

• Blitz <https://github.com/DioxusLabs/blitz> is based on from-scratch implementations of CSS layout and rendering, and wgpu rendering. It’s not usable yet, but is a very interesting concept. If one happens to be familiar with React Native: it’s kinda like that, or React Native Web.

Azul[1] was my solution for that, it was based on WebRender. I didn't get around to finish it in 2019, but I will work on it this year, maybe I'll get it to be mature enough to post it here.

> wide portability (at least Windoze, Linux, MacOS, iOS, Android, embedded: Azul is Windows-Linux-Mac only, don't underestimate the effort to properly port something to a new platform

> "though a Vulkan-based renderer can be made to run pretty much anywhere": WebRender is OpenGL + using software rendering as a fallback

> a permissive open source license: MPL-2.0

> a C interface/wrap to allow a wide programming language binding support: yes

> and an easily extensible and themable set of basic widgets: also yes

[1] https://azul.rs/

There is Iced which is used by system76 in Pop!_OS, Druid [DISCONTINUED], GTK-rs, Relm, Azul and Tauri. Personally I would use Tauri for its speed using the OS's native web render, documentation of use with things such as Sveltekit and the ability to make UI's using JS, CSS and HTML. Tauri similarly to Electron whilst being far faster. But its up to personal preference really. There aren't any solid "go to" options at the moment.

Sounds like you may be interested in azul not exactly servo based but on projects that originate from servo. Also this is not a typical WebView, for example it does not use HTML but uses DOM to define it's UI, and there is no JS engine in there.

Azul uses webrender. But your "glue" program is like half the web browser. You also need a vector graphics library to render websites. Webrender only does boxes, but not complex SVG paths. Once the plan was to use pathfinder, but mozilla fired the dev and they still using an old version of chromium's skia for that.

One day I'll get around to finish my library Azul [1]. Hopefully.

[1] https://azul.rs/

azul