NativeCanvas

Render JavaScript Canvas 2D scripts into native CoreGraphics contexts on Apple platforms.

NativeCanvas evaluates JavaScript templates written against the familiar Canvas 2D API and produces CGImage output backed by CoreGraphics, with no web view required. Templates can declare a typed parameter schema so host applications can drive dynamic graphics (PDFs, animations, data visualisations) with strongly-typed Swift values, while keeping the drawing logic in portable, hot-reloadable JavaScript.

Requirements

• Swift 6+
• macOS 15+ / iOS 18+

Installation

// Package.swift
dependencies: [
    .package(url: "https://github.com/your-org/NativeCanvas", branch: "main")
],
targets: [
    .target(name: "MyTarget", dependencies: ["NativeCanvas"])
]

Quick Start

import NativeCanvas

let templateJS = """
var schema = { name: "Hello World", params: {} };
var layers = [{
    name: "bg",
    render: function(ctx, params, scene) {
        ctx.fillStyle = "navy";
        ctx.fillRect(0, 0, scene.viewport.width, scene.viewport.height);
        ctx.fillStyle = "white";
        ctx.font = nc.pt(64) + "px sans-serif";
        ctx.textAlign = "center";
        ctx.textBaseline = "middle";
        ctx.fillText("Hello!", scene.viewport.width / 2, scene.viewport.height / 2);
    }
}];
"""

// Render to a CGImage
let image: CGImage = try CanvasRenderer.render(
    source: templateJS,
    viewport: CanvasViewport(width: 1920, height: 1080)
)

// Display in SwiftUI
Image(image, scale: 1, label: Text("Canvas"))
    .resizable()
    .aspectRatio(contentMode: .fit)

Documentation

Full documentation is available as a DocC catalog in Sources/NativeCanvas/Documentation.docc/. Generate and browse it with:

swift package generate-documentation --target NativeCanvas

# Serve the docs:
swift package --disable-sandbox preview-documentation --target NativeCanvas

Key articles:

• Getting Started — installation, first render, SwiftUI display, scene parameters, animation
• Architecture — three-layer design (Bridge → Runtime → Renderer), concurrency model
• Writing Templates — template contract, schema declaration, parameter types, nc standard library

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License

This project is licensed under the MIT License.

Copyright (c) 2026 Ben Syverson