Color Manipulation

OpalineColor provides methods for deriving new colors from existing ones — darkening, lightening, and desaturating. These are especially useful for app-level token derivation, where you compute UI-specific colors from a theme's palette.

Methods

All methods take an amount parameter clamped to [0.0, 1.0] and return a new OpalineColor.

darken(amount)

Mix toward black. 0.0 = unchanged, 1.0 = pure black.

let primary = theme.color("accent.primary");
let muted = primary.darken(0.3);      // 30% toward black
let shadow = primary.darken(0.7);     // deep shadow

lighten(amount)

Mix toward white. 0.0 = unchanged, 1.0 = pure white.

let primary = theme.color("accent.primary");
let highlight = primary.lighten(0.2); // subtle highlight
let washed = primary.lighten(0.8);    // nearly white

desaturate(amount)

Mix toward the luminance-equivalent gray (BT.601 weights: R×0.299 + G×0.587 + B×0.114). 0.0 = unchanged, 1.0 = fully gray.

let primary = theme.color("accent.primary");
let muted = primary.desaturate(0.5);  // half-saturation
let gray = primary.desaturate(1.0);   // pure luminance gray

Constants

Two common color constants are available as associated constants:

use opaline::OpalineColor;

OpalineColor::BLACK  // OpalineColor { r: 0, g: 0, b: 0 }
OpalineColor::WHITE  // OpalineColor { r: 255, g: 255, b: 255 }

These are what darken() and lighten() mix toward internally — they all delegate to lerp().

Chaining

Methods return Self, so you can chain them:

let subtle = theme.color("accent.primary")
    .desaturate(0.3)
    .darken(0.1);

Use with Token Derivation

Color manipulation shines when computing app-specific tokens from a theme's core palette:

opaline::load_theme_by_name_with("catppuccin-mocha", |theme| {
    let primary = theme.color("accent.primary");

    theme.register_default_token("bg.hover", primary.darken(0.8));
    theme.register_default_token("bg.selected", primary.darken(0.7));
    theme.register_default_token("text.muted", theme.color("text.primary").desaturate(0.4));
});

See App-Level Derivation for the full pattern.