@termless/swash-render

Pure-native swash text rasterizer for termless — a napi-rs binding that turns a terminal cell grid into an RGBA bitmap.

swash is a pure-Rust, browser-grade headless text rasterizer (the cosmic-text / Linebender lineage): full shaping, TrueType + CFF outlines, and — the reason this package exists — color emoji across sbix / CBDT / COLR. termless's canvas (Skia via @napi-rs/canvas) and resvg renderers both lose the system color-emoji table and fall back to monochrome line-art; swash reads the color tables directly, so 📁 / 📋 / ✅ / 🔥 render in full color.

The native binding is ~1.3 MB — far smaller than @napi-rs/canvas's ~26 MB.

Why a cell-grid API (not SVG)

swash does shaping + glyph rasterization only; it has no cell-grid layout layer. This crate ports the fixed-pitch grid walk (per-cell fg/bg, wide-char advance) — see native/src/lib.rs. termless already owns the cell grid (it feeds both the canvas and resvg renderers), so the public API consumes that grid directly rather than round-tripping through SVG, which would flatten away the very color information swash exists to preserve.

Build

bun run build:prebuild     # napi-rs platform-suffixed .node, e.g. darwin-arm64

The package loader also accepts the legacy local development binary termless-swash-render.node, produced with:

bun run build:native
bun run postbuild:native

Published packages must not include native/target; platform binaries belong in napi-rs optional packages or release artifacts, not in the main tarball.

Usage

import { renderCells } from "@termless/swash-render"

// `term` is any termless Terminal
const bitmap = renderCells(term) // { pixels, width, height }

Or via the termless renderer enum:

termless record --renderer swash -o out.png

await term.screenshot({ renderer: "swash" })