Kosmonaut

 A web browser engine.

Kosmonaut is a web browser engine created to serve as the vehicle for your journey across the world wide web.

The road to the stars is steep and dangerous. But we're not afraid...space flights can't be stopped.

― Yuri Gagarin

 

What can Kosmonaut do?

So far, not much. Only a very limited subset of CSS is currently supported, so most web pages will not work. However, given very basic HTML and CSS, Kosmonaut does render the right things — see Kosmonaut's rendering of this code, compared with that of Firefox.

Here is a summary of things Kosmonaut can do, things I'm currently working on, and things that are towards the front of the todo list.

•  Parse HTML and small subset of CSS into DOM and rules, cascade CSS and apply to DOM
•  Layout and paint of normal flow, block formatting context block-level boxes.
  •  Partial support for abstract box layout with writing-mode and direction properties
•  Layout-tree-dump based testing
•  Support for arbitrary scale factors (e.g. high-DPI monitors)
•  Text rendering with FreeType (without support for text layout — see next item)
•  Support for normal flow, inline formatting context layout and paint

Project goals

Kosmonaut was created with the intention of learning browser engine development. However, the project has come a little ways now, and I've been thinking about niches I can work towards fitting Kosmonaut into. I've shared some thoughts on potential niches in this issue, and would love to hear your ideas too.

Build and test

Kosmonaut is built with Rust using OpenGL bindings via gl-rs, Glutin for window management and OpenGL context creation, Servo's html5ever and cssparser for HTML and CSS parsing, and various other auxiliary libraries.

To build from source:

1. Install Rust: https://www.rust-lang.org/tools/install
2. Install native dependencies, most of which are required for FreeType which Kosmonaut uses for text rendering. For Ubuntu users, see this Dockerfile, and for Arch users this Dockerfile. For those running on other operating systems, you'll need to install the equivalent packages on your system. I'd love to get more documentation on installation for other systems, so open an issue if you have trouble or if you'd like to share your installation process.
3. cargo build

Kosmonaut does not currently support any networking. To render HTML and CSS with Kosmonaut, you may instead run the executable you just built passing any number of HTML and CSS files via the --files (or -f) flag.

cargo run -- --files my.html my.css more.css

To run the rainbow divs example pictured above, try:

cargo run -- --files tests/websrc/rainbow-divs.html tests/websrc/rainbow-divs.css

To run the tests, both unit and layout, run:

cargo test

For layout tests, Kosmonaut transforms the given HTML and CSS into the layout tree and dumps that as text. Those text snapshots are verified with insta.

If you need to review / update snapshots, it is helpful to install the Cargo insta CLI tool like so:

cargo install cargo-insta

from https://github.com/twilco/kosmonaut