vello VS taffy

I'm looking forward to doing careful benchmarking, as this renderer absolutely looks like it will be competitive. It turns out that is really hard to do, if you want meaningful results.

My initial take is that performance will be pretty dependent on hardware, in particular support for pixel local storage[1]. From what I've seen so far, Apple Silicon is the sweet spot, as there is hardware support for binning and sorting to tiles, and then asking for fragment shader execution to be serialized within a tile works well. On other hardware, I expect the cost of serializing those invocations to be much higher.

One reason we haven't done deep benchmarking on the Vello side is that our performance story is far from done. We know one current issue is the use of device atomics for aggregating bounding boxes. We have a prototype implementation [2] that uses monoids for segmented reduction. Additionally, we plan to do f16 math (which should be a major win especially on mobile), as well as using subgroups for various prefix sum steps (subgroups are in the process of landing in WebGPU[3]).

Overall, I'm thrilled to see this released as open source, and that there's so much activity in fast GPU vector graphics rendering. I'd love to see a future in which CPU path rendering is seen as being behind the times, and this moves us closer to that future.

[1]: https://dawn.googlesource.com/dawn/+/refs/heads/main/docs/da...

[2]: https://github.com/linebender/vello/issues/259

[3]: https://github.com/gpuweb/gpuweb/issues/4306

Dioxus is working on this with blitz. It's leveraging wgpu through the linebender group's Vello renderer. Still in early stages.

If you're doing advanced compute work (including lock-free data structures), then it's best effort.

https://github.com/linebender/vello/issues/42 is an issue from when Vello (then piet-gpu) had a single-pass prefix sum algorithm. Looking back, I'm fairly confident that it's a shader translation issue and that it wouldn't work with MoltenVK either, but we stopped investigating when we moved to a more robustly portable approach.

There are a number of up-and-coming Rust-based frameworks in this niche:

- https://github.com/iced-rs/iced (probably the most usable today)

- https://github.com/vizia/vizia

- https://github.com/marc2332/freya

- https://github.com/linebender/xilem (currently very incomplete but exciting because it's from a team with a strong track record)

What is also exciting to me is that the Rust GUI ecosystem is in many cases building itself up with modular libraries. So while we have umpteen competing frameworks they are to a large degree all building and collaborating on the same foundations. For example, we have:

- https://github.com/rust-windowing/winit (cross-platform window creation)

- https://github.com/gfx-rs/wgpu (abstraction on top of vulkan/metal/dx12)

- https://github.com/linebender/vello (a canvas like imperative drawing API on top of wgpu)

- https://github.com/DioxusLabs/taffy (UI layout algorithms)

- https://github.com/pop-os/cosmic-text (text rendering and editing)

- https://github.com/AccessKit/accesskit (cross-platform accessibility APIs)

In many cases there a see https://blessed.rs/crates#section-graphics-subsection-gui for a more complete list of frameworks and foundational libraries)

blessed.rs lists these three crates for 2D drawing: - https://lib.rs/crates/femtovg - https://lib.rs/crates/skia-safe - https://github.com/linebender/vello

Vello (https://github.com/linebender/vello) which uses wgpu to render Edit: just saw you require images. Vello doesn't support those yet

How does this relate to Vello? Both target raw-window-handle for winit compatibility. Vello uses WGPU vs piet-glow using GL.

Finally, maybe vello could help you with ideas. It's not production ready yet, but they have some interesting ideas for 2D rendering using wgpu.

I maintain a standalone web layout engine[0] (currently implementing Flexbox and CSS Grid) which has no scripting support. WPT layout tests using is a major blocker to us running WPT tests against our library. Yoga (used by React Native) is in a similar position.<p>Do you think the WPT would accept pull requests replacing such tests with equivalent tests that don't use <script> (perhaps using a build script to generate multiple tests instead - or simply writing out the tests longhand)?<p>I could run against only the ref-tests, but if I can't get full coverage then the WPT seems to provide little value over our own test suite.<p>[0]: <a href="https://github.com/DioxusLabs/taffy">https://github.com/DioxusLabs/taffy</a>

> Is there any easy to use/hack HTML layouting engine where I could experiment with custom CSS attributes and bridge that gap? Would anything from Servo be suitable?

Servo could be used for this. You'd want to add support for parsing the CSS properties themselves to the style crate in https://github.com/servo/stylo and then the layout implementation to the layout2020 crate in https://github.com/servo/servo. You do effectively get a whole browser though.

I'm currently working on building a lighter weight / hackable layout engine based on a combination of https://github.com/servo/stylo (for css parsing and selector resolution), https://github.com/DioxusLabs/taffy (for box-level layout) and https://github.com/pop-os/cosmic-text (for flow/inline layout). I expect to have something decent in around 6 months

Neither of these setups currently have any support for pagination though.

I maintain a web layout library that is designed to be integrated into other software:

https://github.com/DioxusLabs/taffy

It needs to be combined with a text layout engine (such as https://github.com/pop-os/cosmic-text), and it doesn't support everything yet (notable features that are currently missing: "float", "display: inline-block", "box-sizing: content-box", "position: static"). But we have Block, Flexbox and CSS Grid support with more on the way.

All of these projects have in common that they use Taffy (the project that I work on!) for box-level layout (which currently gives them block, flexbox, and grid layout) , and are either using or planning to use cosmic-text for text/inline layout. This gives you a decent first approximation of web layout, but it's not perfect and there are major features like float, display: inline-block, position: static, box-sizing: content-box missing. Not to mention that none of these implementations currently resolve CSS selectors, so you are effectively limited to inline styles (if you're interested in something in that direction then you may be interested in https://github.com/vizia/vizia).

While there are a lot of Rust UI frameworks, none of them are really recommended for production use yet. I suspect a few of the will die off and work will coalesce a few once things mature a bit.

Another nice feature of the Rust UI ecosystem is that lots of it is being built in a modular way. For example I maintain a layout engine [0] library which just does layout and can be easily integrated by anybody creating a UI library. And there a bunch of similar composable libraries covering rendering, text layout, accessibility, window creation, clipboard access, etc.

[0]: https://github.com/DioxusLabs/taffy

You might be interested in the combination of Taffy [0] which handles box-level browser layout (block, flexbox, grid, etc) and Cosmic Text [1] which handles text-level layout and basic text editing functionality.

Integrating them into browsers while retaining accessibility could be tricky. But in they're general they're relatively small standalone libraries implementing most of the layout algorithms that browsers implement (although there are currently a few key missing features like laying out "inline-block" items in line with text).

[0]: https://github.com/DioxusLabs/taffy

[1]: https://github.com/pop-os/cosmic-text

I maintain a library (https://github.com/DioxusLabs/taffy) that implements both Flexbox and CSS Grid, and is designed to be easily embedded (similar to Yoga, which Ink is using).

https://github.com/DioxusLabs/taffy (disclaimer: I work on this crate) which does CSS layout given CSS styles. This would probably be much more useful once we merge support for display: block (https://github.com/DioxusLabs/taffy/pull/474), and if in the future we support display: table. Taffy doesn't handle text layout but is designed to integrate nicely with external layout systems.

Ok, "1.4GB" made me look into this more. I hadn't realised that we were using a "superlinter" action that includes linters for over 10 languages. Switching to a different github action brought to time down to 3 seconds! https://github.com/DioxusLabs/taffy/pull/463