ThinPath

A memory-first native SVG renderer for iOS, built directly on Core Graphics.

ThinPath parses SVG into a flat, index-based intermediate representation and draws it straight to a CGContext — no node graph, no intermediate bitmaps, no third-party dependencies. It's built for apps that render many SVGs and can't afford the allocation churn or memory footprint of a pointer-linked DOM.

Features

• Renders directly into any CGContext, or rasterizes to a CGImage.
• Flat arena IR: parsed documents are contiguous arrays, not a heap of node objects.
• Shapes, groups, <use>/<symbol> instancing, nested viewports.
• Solid fills, linear/radial gradients, and <pattern> fills.
• Clip paths, masks, opacity, and blending modes.
• Basic <text> with system fonts, and embedded/referenced <image> with on-demand decoding.
• Full SVG transform support and preserveAspectRatio fitting.
• Zero third-party dependencies.

Requirements

• iOS 13+
• Swift 5.9+
• Xcode 15.0+

Installation

Swift Package Manager

Add ThinPath to the dependencies in your Package.swift:

.package(url: "https://github.com/sohandotgit/ThinPath.git", from: "1.0.0")

Then add "ThinPath" to your target's dependencies.

In Xcode, use File → Add Package Dependencies… and paste the repository URL:

https://github.com/sohandotgit/ThinPath.git

Quick Start

import ThinPath

let data = try Data(contentsOf: url)
let (document, _) = parse(data: data)

let renderer = ThinPath()
if let image = renderer.render(document, size: CGSize(width: 200, height: 200), scale: 2) {
    imageView.image = UIImage(cgImage: image)
}

To draw into an existing context instead — e.g. from draw(_:):

renderer.render(document, into: context, rect: bounds)

Documentation

Full documentation is generated with DocC and hosted at sohandotgit.github.io/ThinPath.

• API reference — every entry point and type
• Design docs — how the flat arena and compositing model work
• Examples — copy-paste snippets for common rendering and integration scenarios

Design Notes

The parsed IR is a flat arena of contiguous arrays addressed by integer indices — no class instances and no retain cycles, so dropping a document frees a handful of arrays. Path commands, points, and gradient stops live in shared side arenas, keeping node structs small and fixed-size. Image bitmaps are never retained by the document; they decode on demand at render scale, so long-lived documents stay lean. See Design/MemoryModel.md for the full rationale.

Not yet supported: SMIL/CSS animation, <filter> effects, scripting, and @font-face embedded fonts.

Contributing

Issues and pull requests are welcome. See CONTRIBUTING.md — please open an issue to discuss substantial changes before submitting a PR.

License

ThinPath is available under the MIT License. See LICENSE.