theme/color

Return color with chroma capped at max.

function capChroma(color: string, max: number): string

ui/src/theme/color.ts:381

WCAG 2.x contrast ratio, 1..21.

function contrastRatio(a: string | Rgb, b: string | Rgb): number

ui/src/theme/color.ts:309

Nudge fg lightness away from bg until contrastRatio(fg, bg) >= min, keeping hue/chroma. Returns the first passing color, or the extreme (white / black by surface luminance) when the hue can't reach the target.

function ensureContrast(fg: string, bg: string, min: number): string

ui/src/theme/color.ts:414

Formats a color as CSS: #rrggbb, or rgba() when alpha is below 1.

function formatColor(c: Rgb): string

ui/src/theme/color.ts:123

Tells whether a surface color is dark enough that white text reads better than black.

function isDark(color: string): boolean

ui/src/theme/color.ts:329

WCAG relative luminance, 0 (black) .. 1 (white). Alpha is ignored.

function luminance(color: string | Rgb): number

ui/src/theme/color.ts:295

Perceptual mix in OKLab. t = 0 → a, t = 1 → b. Alpha is mixed linearly.

function mix(a: string, b: string, t: number): string

ui/src/theme/color.ts:344

Convenience: parse → OKLCH → format, for terse palette code.

function oklch(l: number, c: number, h: number, a?: number): string

ui/src/theme/color.ts:145

OKLCH → sRGB with gamut mapping: if the color is out of gamut, chroma is reduced (binary search) until it fits. Lightness and hue are preserved, which is what you want when deriving ramps: a too-vivid accent becomes the most vivid displayable version of itself instead of clipping to a different hue.

function oklchToRgb(c: Oklch): Rgb

ui/src/theme/color.ts:241

Parses a CSS color into sRGB. It accepts #rgb, #rgba, #rrggbb, #rrggbbaa, rgb(), rgba() and oklch(); an OKLCH color out of gamut is chroma-reduced to fit.

function parseColor(input: string): Rgb | undefined

ui/src/theme/color.ts:49

Pick a readable foreground for bg: preferred if it already passes min, else preferred pushed until it does, else pure white/black.

function readableOn(bg: string, preferred: string, min?: number): string

ui/src/theme/color.ts:448

Converts an sRGB color to OKLCH. Near-gray colors get a chroma and hue of 0.

function rgbToOklch(c: Rgb): Oklch

ui/src/theme/color.ts:221

Build a color of the given lightness that carries a faint tint of hue source, the "neutral with personality" every good editor theme uses instead of pure gray. Chroma is tint, clamped to what stays subtle.

function tintedNeutral(l: number, tintSource: string, tint: number): string

ui/src/theme/color.ts:399

Parses a CSS color and converts it to OKLCH.

function toOklch(color: string): Oklch | undefined

ui/src/theme/color.ts:281

Returns color with its alpha replaced.

function withAlpha(color: string, alpha: number): string

ui/src/theme/color.ts:156

Return color with lightness set (0..1), chroma/hue preserved (gamut-mapped).

function withLightness(color: string, l: number): string

ui/src/theme/color.ts:367

Threshold under which a surface is "dark" for the purpose of picking a white vs black foreground. 0.179 is the point where white and black text have equal WCAG contrast against the surface.

const DARK_LUMINANCE_THRESHOLD = 0.179

ui/src/theme/color.ts:321

A color in OKLCH: perceptual lightness, chroma and hue, plus alpha.

interface Oklch

ui/src/theme/color.ts:25

A color in sRGB, every channel from 0 to 1.

interface Rgb

ui/src/theme/color.ts:13