High-Performance CSS Style Engine
Stylo is a high-performance, browser-grade CSS style engine written in Rust that powers Servo and Firefox. This repo contains Servo’s downstream version of Stylo. The upstream version lives in mozilla-central with the rest of the Gecko/Firefox codebase.
Coordination of Stylo development happens:
- Here in Github Issues
- In the #stylo channel of the Servo Zulip
- In the #layout room of the Mozilla Matrix instance (matrix.mozilla.org)
- This Mozilla Hacks article contains a high-level overview of the Stylo architecture.
- There is a chapter in the Servo Book (although it is a little out of date).
The branches are as follows:
- upstream has upstream mozilla-central filtered to the paths we care about (style.paths), but is otherwise unmodified.
- main adds our downstream patches, plus the scripts and workflows for syncing with mozilla-central on top of upstream.
Warning
This repo syncs from upstream by creating a new branch and then rebasing our changes on top of it. This means that git pull will not work across syncs (you will need to use git fetch, git reset and git rebase).
More information on the syncing process is available in SYNCING.md
A guide to the crates contained within this repo
These crates are largely implementation details of Stylo, although you may need to use some of them directly if you use Stylo.
| Directory | Crate | Notes |
|---|---|---|
| style | |
The main Stylo crate containing the entire CSS engine |
| style_traits |  |
Types and traits which allow other code to interoperate with Stylo without depending on the main crate directly. |
| stylo_dom |  |
Similar to stylo_traits (but much smaller) |
| stylo_atoms |  |
Atoms for CSS and HTML event related strings |
| stylo_config |  |
Configuration for Stylo. Can be used to set runtime preferences (enabling/disabling properties, etc) |
| stylo_static_prefs |  |
Static configuration for Stylo. Config be overridden by patching in a replacement crate. |
| style_derive |  |
Internal derive macro for stylo crate |
These crates form part of Stylo but are also be useful standalone.
| Directory | Crate | Notes |
|---|---|---|
| selectors |  |
CSS Selector matching |
| servo_arc |  |
A variant on std::Arc |
You may also be interested in the cssparser crate which lives in the servo/rust-cssparser repo.
Low-level crates which could technically be used standalone but are unlikely to be generally useful in practice.
| Directory | Crate | Notes |
|---|---|---|
| malloc_size_of |  |
Heap size measurement for Stylo values |
| to_shmem |  |
Internal utility crate for sharing memory across processes. |
| to_shmem_derive |  |
Internal derive macro for to_shmem crate |
Assuming your local servo and stylo directories are siblings, you can build servo against stylo by adding the following to servo/Cargo.toml:
[patch."https://github.com/servo/stylo"]
selectors = { path = "../stylo/selectors" }
servo_arc = { path = "../stylo/servo_arc" }
stylo_atoms = { path = "../stylo/stylo_atoms" }
stylo = { path = "../stylo/style" }
stylo_config = { path = "../stylo/stylo_config" }
stylo_dom = { path = "../stylo/stylo_dom" }
stylo_malloc_size_of = { path = "../stylo/malloc_size_of" }
stylo_traits = { path = "../stylo/style_traits" }Stylo is licensed under MPL 2.0
