Introduction

Why

SVG has no built-in text measurement or layout: you cannot auto-size text to fit a container, wrap lines, or use flexbox the way HTML does. The usual workarounds — canvas.measureText, hidden DOM elements — depend on the runtime, so the same document can measure differently across OS fonts and browser engines.

boundsvg takes OS font measurement out of the equation. Font shaping (HarfRust, HarfBuzz-compatible) and layout (Taffy flexbox and CSS Grid) run in version-pinned WASM against fonts you supply. Within one boundsvg version, accepted owned inputs produce byte-identical SVG, PNG, WebP, and GIF artifacts across supported runtimes after any documented normalization. Raw embedded SVG, live animation scheduling, and external video encoders have explicit boundaries in the determinism contract. Text can shrink or grow to fit its container, wrap, truncate with an ellipsis, or stop at a line limit.

Examples

Packages

The nine publishable packages, plus the three playground apps. Internal tooling (@boundsvg/docs, @boundsvg/playground-shared, @boundsvg/bench, @boundsvg/boundtext-visual-validator) is private and not listed.

Package	Path	Description
@boundsvg/core	packages/core	Main library — text measurement, layout, SVG/PNG/WebP/GIF emit
@boundsvg/react	packages/react	React integration — Provider, hooks, <BoundSvg> component
@boundsvg/worker	packages/worker	Web Worker adapter — off-main-thread rendering
@boundsvg/cli	packages/cli	CLI tool — convert, export, inspect, doctor
@boundsvg/browser	packages/browser	Browser WASM loader and SVG DOM utilities
@boundsvg/video	packages/video	Browser MP4 export — WebCodecs H.264 plus a bundled muxer
@boundsvg/extras	packages/extras	Unstyled utility components — HStack, FitText, etc.
@boundsvg/shape	packages/shape	Geometry / symbol data builders for Shape and Symbol
@boundsvg/testing	packages/testing	Test helpers — SVG snapshots, warnings, Vitest matchers
@boundsvg/playground-react	apps/playground-react	Interactive React demo app
@boundsvg/playground-core	apps/playground-core	Core API demo (no React, TypeScript + Vite)
@boundsvg/playground-cli	apps/playground-cli	CLI demo — SVG analysis + multi-format output

Architecture

VNode → Validate → Build Taffy Tree → Compute Layout
  → Text Resolve → Build IR → Emit (SVG/PNG/WebP/GIF)

License

boundsvg is licensed under either the MIT License or the Apache License 2.0, at your option.