swatchly-color

The color engine behind Swatchly, a free color palette generator. It is pure Rust with zero dependencies, and runs natively, in the browser through WebAssembly, and in Cloudflare Workers.

Features

• Conversions: sRGB ⇄ HSL, HSV/HSB, HWB, CMYK, CIE XYZ, Lab, LCh, Luv, OKLab and OKLCH. OKLCH output is gamut-mapped, which reduces chroma while keeping hue.
• Palette generation in OKLCH: auto, monochromatic, analogous, complementary, split-complementary, triadic, tetradic and square. Locked colors act as constraints. Output is deterministic for a given seed.
• Variations: shades, tints, tones, hues, temperatures, OKLab gradients, Tailwind-style 50–950 scales, and palette-wide hue/saturation/brightness/temperature adjustment.
• Accessibility:
  • WCAG 2.x contrast ratio with AA/AAA verdicts
  • An enhance function that fixes failing pairs by adjusting lightness
  • APCA (the WCAG 3 draft method)
  • Color-vision-deficiency simulation for 8 types (Machado et al. 2009)
• Image palette extraction: deterministic k-means++ in OKLab over raw RGBA pixels.
• Color names: nearest-name lookup over ~5,000 names, from the MIT-licensed color-names dataset.
• Description: hue family, temperature, and wording like "a dark, muted blue".
• Exports: CSS (HEX/RGB/HSL), SCSS, Tailwind v3/v4, JSON, CSV, XML, SVG, Adobe ASE and PDF. All are written by hand, with no dependencies.

Usage

[dependencies]
swatchly-color = "0.1"

use color_core::{Rgb, Palette};
use color_core::contrast::{ratio, verdict, apca};
use color_core::generate::{generate, Method};
use color_core::rng::Rng;
use color_core::spaces::to_oklch;

let navy = Rgb::from_hex("#1b264f").unwrap();
let cream = Rgb::from_hex("f4e9cd").unwrap();

// WCAG 2 and APCA contrast
let r = ratio(navy, cream);          // 12.10
assert!(verdict(r).aaa_small);
let lc = apca(navy, cream);          // Lc 88.6

// Generate a 5-color palette that keeps `navy` locked in the first slot
let slots = [Some(navy), None, None, None, None];
let colors = generate(&slots, Method::Analogous, &mut Rng::new(42));
let palette = Palette(colors);
println!("https://swatchly.xyz/generate/{}", palette.slug());

// Perceptual coordinates
let [l, c, h] = to_oklch(navy);

The library is imported as color_core. Run this example with cargo run --example readme.

Used by

• swatchly.xyz runs this crate in two places: in the browser through Leptos/WASM (the palette generator and every tool), and at the edge through a Rust Cloudflare Worker (16.7M color pages).

License

MIT. The bundled color names come from meodai/color-names (MIT).