Pax

Pax is a user interface language and 2D layout engine. Use Pax to develop cross-platform apps with Rust.

Example

Writing Pax is intended to feel familiar and the language borrows many ideas from prior art.

Following is a simple Pax component called IncrementMe:

//File: increment-me.rs

use pax::*;
use pax_std::{Text};
use pax_std::forms::{Button, ArgsButtonSubmit};
use pax_std::layout::{Stacker};

/// Defines the Pax component `IncrementMe`, with template & settings specified in `increment-me.pax`.
#[pax_component("increment-me.pax")] 
pub struct IncrementMe {
  pub num_clicks: Property<i64>
}
impl IncrementMe {
  pub async fn increment(&self, args: ArgsButtonSubmit) {
    let old_num_clicks = self.num_clicks.get();
    self.num_clicks.set(old_num_clicks + 1);
  }
}

//File: increment-me.pax

<Stacker cells=2>
  <Text>{"I have been clicked " + self.num_clicks + " times."}</Text>
  <Button @submit=self.increment>"Increment me!"</Button>
</Stacker>

Any Pax component like the example above may be included inside other Pax components, or may be mounted as the root of a stand-alone app.

See a more thorough, running example.

Features

• Fast — 120fps animations enabled by native rendering and native runtimes for each supported platform
• Accessible — Support for native screen readers for text & GUI elements, as well as SEO on the Web
• Lightweight — Under 100kB baseline for WebAssembly binary
• Declarative UI language makes it easy to reason about complex scenes and GUIs, as well as build tooling that reads & writes Pax
• Expressive — Free-form drawing and animation toolkit alongside GUI form elements and layouts
• Extensible — UI component system built around Rust structs enables modular application building and publication of reusable components through cargo and crates.io. Pax's standard library (pax-std) is a canonical example, including modular primitives like <Group />, drawing elements like <Rectangle />, form elements like <Text />, and layout elements like <Stacker />.
• Cross-platform — Pax projects compiles through Rust into machine code, currently 1. a completely native Mac app (via LLVM, CoreGraphics, and SwiftUI) or 2. a Web app (via WebAssembly). Support for more platforms is planned, at least: Linux, Windows, iOS, and Android.

Docs

Read more in The Pax Docs

Getting Started

Pax is being developed in the open in an unstable alpha preview. You cannot yet, without pain, create an app. If you want to collaborate on library development at this stage, reach out on Discord.

Once Pax reaches Alpha — soon — this section will be updated to include simple instructions for getting started.

Current status & support

Pax is in alpha-preview and is not yet viable for building apps — read the latest status.

Support matrix:

	Web browsers	Native iOS	Native Android	Native macOS	Native Windows	Native Linux
Development harness & chassis	✅	⏲	⏲	✅	⏲	⏲
2D rendering and UIs	✅ Canvas	⏲ CoreGraphics	⏲ Cairo	✅ CoreGraphics	⏲ Direct2D	⏲ Cairo
3D rendering and UIs	⏲	⏲	⏲	⏲	⏲	⏲
Vector graphics APIs	✅	⏲	⏲	✅	⏲	⏲
2D layouts	✅	⏲	⏲	✅	⏲	⏲
Animation APIs	✅	⏲	⏲	✅	⏲	⏲
Native text rendering	✅ DOM	⏲ UIKit	⏲ android:*	✅ SwiftUI	⏲ System.Windows.Forms	⏲ GTK
Native form elements	⏲ DOM	⏲ UIKit	⏲ android:*	⏲ SwiftUI	⏲ System.Windows.Forms	⏲ GTK
Native event handling (e.g. Click, Tap)	✅	⏲	⏲	✅	⏲	⏲
Rust host language	✅ WASM	⏲ LLVM	⏲ LLVM	✅ LLVM	⏲ LLVM	⏲ LLVM
JS/TypeScript host language	⏲	⏲	⏲	⏲	⏲	⏲

Legend:
✅ Supported
⏲ Not yet supported

License

© 2023 PaxCorp Inc. [contact@pax.rs].

This project is licensed under either of:

• MIT license
• Apache 2.0 License

at your option.

Library Development

Environment setup

Use rustc 1.65.0 via rustup

To build .pax => Web

• Install 'wasm-pack' via:

   cargo install wasm-pack

• Install node v14 LTS, recommended via nvm

  # First install nvm
  curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.39.3/install.sh | bash
  # After restarting terminal:
  nvm install 14
  nvm use 14 --default

• Install yarn:

  # if necessary: sudo chown -R yourusername /usr/local/lib/node_modules 
  npm i --global yarn

To build .pax => macOS

• Install xcode >=14.3 and Xcode command line utils: xcode-select --install
• SDK Version macosx13.3, Xcode version >=14.3
• Current Minimum Deployment 13.0

Running Development Environment

First, refer to the latest project status

Run pax-example:

# after cloning pax, from `pax/`
cd pax-example
# the `./pax` shell script emulates the `pax` CLI for Pax monorepo development
./pax run --target=macos # or --target=web 

To initialize the submodules, for super-grep powers:

git submodule update --init --recursive

As needed, review the git submodule docs.

Architectural Reference

Runtime dependency & codegen graph

Pax compiler sequence diagram | Compiler source