Pax

Pax is a user interface engine for native apps and websites.

This repository includes:

The Pax compiler and language implementation
Native runtimes
Language bindings for supported programming languages, currently only Rust
Pax's CLI for compiling and managing projects
Example projects

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: lib.rs
use pax_lang::*;
use pax_lang::api::*;
use pax_std::primitives::*;
use pax_std::types::*;
use pax_std::types::text::*;
use pax_std::components::Stacker;

/// Defines the Pax component `IncrementMe`, with template & settings specified in `increment-me.pax`.
#[derive(Pax)]
#[main]
#[file("increment-me.pax")]
pub struct IncrementMe {
    pub num_clicks: Property<u32>,
    pub message: Property<String>,
}

impl IncrementMe {
    pub fn handle_did_mount(&mut self, ctx: RuntimeContext) {
        self.num_clicks.set(0);
        self.message.set("0 clicks".to_string());
    }
    pub fn increment(&mut self, ctx: RuntimeContext, args: ArgsClick){
        let old_num_clicks = self.num_clicks.get();
        self.num_clicks.set(old_num_clicks + 1);
        self.message.set(format!("{} clicks", self.num_clicks.get()));
    }

}

//increment-me.pax
<Text text={self.message} class=centered class=small id=text />
<Rectangle class=centered class=small @click=self.increment
    fill={Fill::Solid(Color::rgba(0.0,0.0,0.0,1.0))} 
    corner_radii={RectangleCornerRadii::radii(10.0,10.0,10.0,10.0)}
/>

@handlers{
     did_mount:handle_did_mount
}

@settings {
     .centered {
        x: 50%
        y: 50%
        anchor_x: 50%
        anchor_y: 50%
    } 
    .small {
        width: 120px
        height: 120px
    }
    #text {
        style: {
                font: {Font::system("Times New Roman", FontStyle::Normal, FontWeight::Bold)},
                font_size: 32px,
                fill: {Color::rgba(1.0, 1.0, 1.0, 1.0)},
                align_vertical: TextAlignVertical::Center,
                align_horizontal: TextAlignHorizontal::Center,
                align_multiline: TextAlignHorizontal::Center
        }
    }
}

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 — 240fps animations, compiles to machine code
Native — Platform-native text, UI controls, and drawing APIs.
Accessible — Supports screen readers for native text & GUI elements, as well as SEO on the Web
Lightweight — <100kB footprint baseline for WebAssembly binary. No web tech in desktop & mobile builds.
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, plus GUI form elements and responsive layouts. Blur the lines between work & play, function & art.
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, publishing modular primitives like <Group />, drawing elements like <Rectangle />, form elements like <Text />, and layout elements like <Stacker />.

Docs

Getting Started

Setup, macOS workstation

Install rustc 1.70.0 via rustup
Install the Pax CLI: cargo install pax-cli
Follow instructions to build for WebAssembly or macOS below
Create a new project pax-cli new my-first-project

Setup, Linux (Debian / Ubuntu) workstation

Install rustc 1.70.0 via rustup
Install development dependencies: apt install pkg-config libssl-dev
Install the Pax CLI: cargo install pax-cli
Follow instructions to build for WebAssembly below
Create a new project pax-cli new my-first-project

Setup, Windows workstation

Install rustc via installer
Install the Pax CLI: cargo install pax-cli
Follow instructions to build for WebAssembly below
Create a new project pax-cli new my-first-project

To build Pax projects for WebAssembly

Install 'wasm-pack' via:
```
 curl https://rustwasm.github.io/wasm-pack/installer/init.sh -sSf | sh 
```
For Windows, follow instructions to use installer here.

Install node v20 LTS, recommended via nvm

# For macOS / Linux:  first install nvm
curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.39.3/install.sh | bash
# After restarting terminal:
nvm install 20
nvm use 20 --default

For Windows, install nvm-windows and install Node v20 LTS.

To build Pax projects as native macOS apps

Building macOS apps requires running a Mac with macOS. This is a constraint enforced technically and legally by Apple.
Install xcode >=15.0 and Xcode command line utils: xcode-select --install
Make sure to accept Xcode's license agreement (prompted during Xcode startup for the first time)
SDK Version macosx13.3, Xcode version >=15.0
Current Minimum Deployment 13.0
Install all necessary build architectures for Rust, so that binaries can be built for both Intel and Apple Silicon macs
```
rustup target add aarch64-apple-darwin x86_64-apple-darwin
```

To build Pax projects as native iOS apps

Follow instructions for building native macOS apps, above
Install all necessary build architectures for Rust, so that binaries can be built for iOS and simulator targets:
```
rustup target add aarch64-apple-ios x86_64-apple-ios aarch64-apple-ios-sim
```
Install ios simulator through Xcode

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	✅ SwiftUI	⏲ android:*	✅ SwiftUI	⏲ System.Windows.Forms	⏲ GTK
Native form elements	⏲ DOM	⏲ SwiftUI	⏲ 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

This project is licensed under either of:

at your option.

Running Monorepo 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.

pax-lang/pax

Pax