palette-core

TOML-defined theme system with inheritance and multi-target export.

Themes are authored as TOML presets. Variants inherit from a base and override only what changes. The crate parses, merges, and converts them into typed palettes for any rendering target.

Usage

use palette_core::registry::load_preset;

let palette = load_preset("tokyonight_storm")?;

CSS custom properties

use palette_core::css::to_css_custom_properties;
use palette_core::registry::{load_preset, preset_ids};

// Single theme
let props = to_css_custom_properties(&palette, "app");
let css = format!(":root {{\n{props}}}");

// Multiple themes for live switching
let mut css = String::new();
for id in preset_ids() {
    let palette = load_preset(id)?;
    let props = to_css_custom_properties(&palette, "app");
    css.push_str(&format!("[data-theme=\"{id}\"] {{\n{props}}}\n"));
}

Single-theme output:

:root {
  --app-base-background: #1a1b26;
  --app-base-foreground: #c0caf5;
  --app-semantic-error: #db4b4b;
  /* ... */
}

Multi-theme output scopes each theme under a data-theme attribute. Switch themes by setting the attribute on <html>:

<html data-theme="tokyonight">

document.documentElement.dataset.theme = "catppuccin";

Then reference the variables in your components:

body { background: var(--app-base-background); color: var(--app-base-foreground); }

The prefix argument namespaces every variable, so multiple palettes can coexist.

Terminal (ratatui)

use palette_core::registry::load_preset;
use palette_core::terminal::to_terminal_theme;

let palette = load_preset("catppuccin")?;
let theme = to_terminal_theme(&palette);
// theme.base["background"], theme.semantic["error"], etc.

WCAG contrast validation

use palette_core::registry::load_preset;
use palette_core::contrast::{validate_palette, ContrastLevel};

let palette = load_preset("tokyonight")?;
let violations = validate_palette(&palette, ContrastLevel::AaNormal);
for v in &violations {
    println!("{} on {}: {:.2}:1", v.foreground_label, v.background_label, v.ratio);
}

Color manipulation

use palette_core::color::Color;
use palette_core::manipulation::blend;

let base = Color::from_hex("#1a1b26")?;

let hover = base.lighten(0.1);
let disabled = base.desaturate(0.3);
let accent = base.rotate_hue(180.0);

let overlay = blend(Color::from_hex("#FF0000")?, base, 0.5);

Available methods: lighten, darken, saturate, desaturate, rotate_hue. All take absolute amounts (CSS model). Non-finite inputs return the color unchanged.

Snapshot (JSON export)

use palette_core::registry::load_preset;
use palette_core::snapshot::{to_json, to_json_value};

let palette = load_preset("nord")?;
let json = to_json(&palette)?;
let value = to_json_value(&palette)?; // serde_json::Value

Platform overrides

use palette_core::registry::load_preset;
use palette_core::platform::from_sections;

let manifest = palette_core::manifest::PaletteManifest::from_toml(toml_str)?;
let overrides = from_sections(&manifest.platform)?;
// overrides["terminal"].background, overrides["web"].foreground, etc.

egui

use palette_core::registry::load_preset;
use palette_core::egui::to_egui_visuals;

let palette = load_preset("github_dark")?;
ctx.set_visuals(to_egui_visuals(&palette));

Features

Feature	Dependency	What it adds
`terminal`	`ratatui`	`Palette` → `ratatui::style::Color` maps
`egui`	`egui`	`Palette` → `egui::Visuals`
`snapshot`	`serde_json`	JSON serialization of `Palette`
`platform`	—	Parse `[platform.terminal]` / `[platform.web]` overrides
`full`	all of the above	Everything

Core functionality (parsing, merge, CSS export, WCAG contrast checking, color manipulation) has no optional dependencies.

Bundled presets

Family	Presets
Ayu	`ayu_dark`, `ayu_light`, `ayu_mirage`
Catppuccin	`catppuccin`, `catppuccin_frappe`, `catppuccin_latte`, `catppuccin_macchiato`
Dracula	`dracula`
Everforest	`everforest_dark`, `everforest_light`
GitHub	`github_dark`, `github_light`
Gruvbox	`gruvbox_dark`, `gruvbox_light`
Kanagawa	`kanagawa`
Monokai	`monokai`
Nord	`nord`
One	`one_dark`, `one_light`
Rosé Pine	`rose_pine`, `rose_pine_dawn`, `rose_pine_moon`
Solarized	`solarized_dark`, `solarized_light`
TokyoNight	`tokyonight`, `tokyonight_storm`, `tokyonight_day`, `tokyonight_moon`

All presets are embedded at compile time via include_str!. Use registry::preset_ids() to list them.

Preset format

Base presets define all sections. Variants declare inherits in [meta] and override only differing values.

[meta]
name = "My Theme Storm"
preset_id = "my_theme_storm"
schema_version = "1"
style = "storm"
kind = "preset-variant"
inherits = "my_theme"

[base]
background = "#24283b"

Sections: base, semantic, diff, surface, typography, syntax, editor, terminal.

License

Licensed under either of Apache License, Version 2.0 or MIT License at your option.

palette-core 0.3.5