kolor-seed

One seed color. Full Material 3 palette. Pure Kotlin. Zero dependencies.

kolor-seed generates complete Material 3 color palettes from a single seed color, using a pure Kotlin implementation of the HCT (Hue-Chroma-Tone) color space. It works everywhere Kotlin runs -- Android, iOS, Desktop, Web, and server-side -- with no platform dependencies.

Why kolor-seed?

• Truly multiplatform -- JVM, JS (IR), macOS, iOS, Linux, Windows. No android.graphics.Color or any platform API.
• Zero runtime dependencies -- Only kotlin-stdlib. Nothing else.
• Blazing fast -- Seed to full light+dark scheme in under 1ms. @JvmInline value class Color for zero-cost abstraction on JVM.
• Material 3 compliant -- All 29+ color roles, 6 tonal palette groups, custom color harmonization.
• Developer-friendly API -- One line to generate a theme. Full HCT access when you need fine control.

Installation

Add the JitPack repository to your settings.gradle.kts:

dependencyResolutionManagement {
    repositories {
        mavenCentral()
        maven { url = uri("https://jitpack.io") }
    }
}

Then add the dependency:

// build.gradle.kts
dependencies {
    // Core: HCT, palettes, schemes (no UI dependency)
    implementation("com.github.ikeno-web.kolor-seed:kolor-seed-core:v0.1.1")

    // Optional: Compose Color extensions
    implementation("com.github.ikeno-web.kolor-seed:kolor-seed-compose:v0.1.1")
}

Quick Start

Generate a full theme in one line

import io.github.nunoikeno.kolorseed.*

val (light, dark) = colorSchemes("#6750A4")

// Access any of the 29+ color roles
println(light.primary.toHex())           // "#6750A4"
println(light.primaryContainer.toHex())  // "#EADDFF"
println(dark.primary.toHex())            // "#D0BCFF"

Use with Compose / Compose Multiplatform

import io.github.nunoikeno.kolorseed.*
import io.github.nunoikeno.kolorseed.compose.*

@Composable
fun AppTheme(
    seedColor: String = "#6750A4",
    darkTheme: Boolean = isSystemInDarkTheme(),
    content: @Composable () -> Unit
) {
    val seed = Color.fromHex(seedColor)
    val scheme = if (darkTheme) ColorScheme.dark(seed) else ColorScheme.light(seed)

    // Convert to Compose Colors and apply
    MaterialTheme(
        colorScheme = lightColorScheme(
            primary = scheme.primary.toComposeColor(),
            onPrimary = scheme.onPrimary.toComposeColor(),
            // ... map all roles
        ),
        content = content
    )
}

Fine-tune with HCT

import io.github.nunoikeno.kolorseed.*

val brand = Color.fromHex("#FF5722")
val hct = brand.toHct()

println("Hue: ${hct.hue}, Chroma: ${hct.chroma}, Tone: ${hct.tone}")

// Adjust individual perceptual attributes
val lighter = hct.withTone(80.0).toColor()
val muted   = hct.withChroma(24.0).toColor()
val shifted = hct.withHue((hct.hue + 30.0) % 360.0).toColor()

Harmonize brand colors

val seed  = Color.fromHex("#6750A4")
val brand = Color.fromHex("#2E7D32")

// Shift brand green's hue towards the seed -- keeps it green, but cohesive
val harmonized = Blend.harmonize(brand, seed)

// Or add it as a full custom color group
val palette = CorePalette.fromSeed(seed)
    .withCustomColor("brand", brand, harmonize = true)
val scheme = palette.lightScheme()
val brandRoles = scheme.customColors["brand"]!!

Check accessibility

val scheme = ColorScheme.light(Color.fromHex("#6750A4"))

val ratio = Contrast.ratioOf(scheme.onPrimary, scheme.primary)
println("Contrast: $ratio")                                      // e.g. 12.7
println("WCAG AA: ${Contrast.meetsAA(scheme.onPrimary, scheme.primary)}")  // true

Export to CSS or Figma

val scheme = ColorScheme.light(Color.fromHex("#6750A4"))

// CSS custom properties
println(scheme.toCssCustomProperties())
// --md-sys-color-primary: #6750A4;
// --md-sys-color-on-primary: #FFFFFF;
// ...

// JSON for CI pipelines
println(scheme.toJson())

// Figma Tokens
println(scheme.toFigmaTokens())

API Overview

Core Module (kolor-seed-core)

Class / Object	Description
Color	Inline value class wrapping ARGB int. HEX/RGB/HSL conversion.
Hct	HCT color space. Perceptually uniform hue, chroma, tone manipulation.
TonalPalette	101 tones (0..100) for a single hue/chroma. Cached for performance.
CorePalette	6 tonal palettes (Primary, Secondary, Tertiary, Neutral, NeutralVariant, Error) from one seed.
ColorScheme	All Material 3 color roles (primary, onPrimary, surface, etc.) for light or dark theme.
Blend	Color harmonization and perceptual blending (HCT hue, CAM16 UCS).
Contrast	WCAG 2.1 contrast ratio calculation. AA/AAA level checks.
HslColor	HSL color space conversion.

Compose Extension (kolor-seed-compose)

Function	Description
Color.toComposeColor()	kolor-seed Color to androidx.compose.ui.graphics.Color
ComposeColor.toKolorSeed()	Compose Color to kolor-seed Color

Top-level Convenience Functions

val light = lightColorScheme("#6750A4")
val dark  = darkColorScheme("#6750A4")
val (light, dark) = colorSchemes("#6750A4")

Targets

Platform	Target
JVM	jvm (Java 17+)
JavaScript	js(IR) -- browser + Node.js
macOS	macosX64, macosArm64
iOS	iosX64, iosArm64, iosSimulatorArm64
Linux	linuxX64
Windows	mingwX64

Building

# Build all targets
./gradlew build

# Run tests (all platforms)
./gradlew allTests

# Run tests (JVM only -- fast feedback)
./gradlew :kolor-seed-core:jvmTest

# Publish to local Maven
./gradlew publishToMavenLocal

Design Principles

1. Zero dependencies -- Core module depends only on kotlin-stdlib. No reflection, no serialization libraries, no platform APIs.
2. Pure functions -- Every function is side-effect-free, thread-safe, and deterministic.
3. Performance -- @JvmInline value class for Color, tone caching in TonalPalette, inline functions on hot paths.
4. Material 3 fidelity -- Output matches Google's material-color-utilities within rounding tolerance.

License

Copyright 2026 nunoikeno

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

See LICENSE for the full text.