Enum Color 

#[non_exhaustive]
pub enum Color {
    Reset,
    Black,
    Red,
    Green,
    Yellow,
    Blue,
    Magenta,
    Cyan,
    White,
    DarkGray,
    LightRed,
    LightGreen,
    LightYellow,
    LightBlue,
    LightMagenta,
    LightCyan,
    LightWhite,
    Rgb(u8, u8, u8),
    Indexed(u8),
}

Terminal color.

Covers the standard 16 named colors, 256-color palette indices, and 24-bit RGB true color. Use Color::Reset to restore the terminal’s default foreground or background.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

Reset

Reset to the terminal’s default color.

Black

Standard black (color index 0).

Red

Standard red (color index 1).

Green

Standard green (color index 2).

Yellow

Standard yellow (color index 3).

Blue

Standard blue (color index 4).

Magenta

Standard magenta (color index 5).

Cyan

Standard cyan (color index 6).

White

Standard white (color index 7).

DarkGray

Bright black / dark gray (color index 8).

LightRed

Bright red (color index 9).

LightGreen

Bright green (color index 10).

LightYellow

Bright yellow (color index 11).

LightBlue

Bright blue (color index 12).

LightMagenta

Bright magenta (color index 13).

LightCyan

Bright cyan (color index 14).

LightWhite

Bright white (color index 15).

Rgb(u8, u8, u8)

24-bit true color.

Indexed(u8)

256-color palette index.

Implementations

impl Color

pub fn luminance(self) -> f32

Compute relative luminance using ITU-R BT.709 coefficients.

Returns a value in [0.0, 1.0] where 0 is darkest and 1 is brightest. Use this to determine whether text on a given background should be light or dark.

Example

use slt::Color;

let dark = Color::Rgb(30, 30, 46);
assert!(dark.luminance() < 0.15);

let light = Color::Rgb(205, 214, 244);
assert!(light.luminance() > 0.6);

pub fn contrast_fg(bg: Color) -> Color

Return a contrasting foreground color for the given background.

Uses the WCAG 2.1 relative luminance threshold (0.179) to decide between white and black text. For theme-aware contrast, prefer using this over hardcoding theme.bg as the foreground.

Example

use slt::Color;

let bg = Color::Rgb(189, 147, 249); // Dracula purple
let fg = Color::contrast_fg(bg);
// Dracula purple → white (WCAG luminance 0.385 < 0.179 threshold)

pub fn blend(self, other: Color, alpha: f32) -> Color

Blend this color over another with the given alpha.

alpha is in [0.0, 1.0] where 0.0 returns other unchanged and 1.0 returns self unchanged. Both colors are resolved to RGB.

Example

use slt::Color;

let white = Color::Rgb(255, 255, 255);
let black = Color::Rgb(0, 0, 0);
let gray = white.blend(black, 0.5);
// ≈ Rgb(128, 128, 128)

pub fn lighten(self, amount: f32) -> Color

Lighten this color by the given amount (0.0–1.0).

Blends toward white. amount = 0.0 returns the original color; amount = 1.0 returns white.

pub fn darken(self, amount: f32) -> Color

Darken this color by the given amount (0.0–1.0).

Blends toward black. amount = 0.0 returns the original color; amount = 1.0 returns black.

pub fn contrast_ratio(a: Color, b: Color) -> f32

Compute the WCAG 2.1 contrast ratio between two colors.

Returns a value >= 1.0. A ratio >= 4.5 meets WCAG AA for normal text;

= 3.0 meets AA for large text.

Example

use slt::Color;

let ratio = Color::contrast_ratio(Color::White, Color::Black);
assert!(ratio > 15.0);

pub fn meets_contrast_aa(fg: Color, bg: Color) -> bool

Returns true if the contrast ratio between two colors meets WCAG AA for normal text (ratio >= 4.5).

pub fn downsampled(self, depth: ColorDepth) -> Color

Downsample this color to fit the given color depth.

• TrueColor: returns self unchanged.
• EightBit: converts Rgb to the nearest Indexed color.
• Basic: converts Rgb and Indexed to the nearest named color.
• NoColor: returns Color::Reset — emit no ANSI color at all.

Named colors (Red, Green, etc.) and Reset pass through at depths other than NoColor.

pub fn from_hex(s: &str) -> Option<Color>

Parse a hex string (#rgb or #rrggbb) into Color::Rgb.

The leading # is required. Short form #rgb expands each nibble (#abc → Rgb(0xaa, 0xbb, 0xcc)). Returns None for any malformed input (wrong length, non-hex digits, missing #).

Example

use slt::Color;

assert_eq!(Color::from_hex("#ff6b6b"), Some(Color::Rgb(255, 107, 107)));
assert_eq!(Color::from_hex("#abc"), Some(Color::Rgb(170, 187, 204)));
assert_eq!(Color::from_hex("ff6b6b"), None); // missing '#'
assert_eq!(Color::from_hex("#xyz"), None); // non-hex

pub fn to_hex(self) -> String

Format an Rgb color as a #rrggbb hex string.

Non-Rgb variants are first resolved to their RGB equivalent via the internal palette, so the result is always a valid #rrggbb token.

Example

use slt::Color;

assert_eq!(Color::Rgb(255, 107, 107).to_hex(), "#ff6b6b");

pub fn from_hsl(h: f32, s: f32, l: f32) -> Color

Construct an Color::Rgb from HSL components.

h is the hue in degrees (wrapped into 0..360), s is the saturation and l the lightness, both clamped to [0.0, 1.0].

Example

use slt::Color;

assert_eq!(Color::from_hsl(0.0, 1.0, 0.5), Color::Rgb(255, 0, 0));
assert_eq!(Color::from_hsl(120.0, 1.0, 0.5), Color::Rgb(0, 255, 0));
assert_eq!(Color::from_hsl(240.0, 1.0, 0.5), Color::Rgb(0, 0, 255));

pub fn from_hsv(h: f32, s: f32, v: f32) -> Color

Construct an Color::Rgb from HSV (a.k.a. HSB) components.

h is the hue in degrees (wrapped into 0..360), s is the saturation and v the value/brightness, both clamped to [0.0, 1.0].

Example

use slt::Color;

assert_eq!(Color::from_hsv(0.0, 1.0, 1.0), Color::Rgb(255, 0, 0));
assert_eq!(Color::from_hsv(120.0, 1.0, 1.0), Color::Rgb(0, 255, 0));
assert_eq!(Color::from_hsv(0.0, 0.0, 1.0), Color::Rgb(255, 255, 255));

pub fn rotate_hue(self, degrees: f32) -> Color

Rotate the hue of this color by degrees around the HSL color wheel.

The color is resolved to RGB, converted to HSL, rotated, and converted back to Color::Rgb. Positive values rotate forward (red → green → blue); negative values rotate backward. The result is always an Rgb color regardless of the input variant — named and indexed colors are first resolved via the internal palette.

Example

use slt::Color;

// Rotating pure red by 120° lands on pure green.
assert_eq!(Color::Rgb(255, 0, 0).rotate_hue(120.0), Color::Rgb(0, 255, 0));

Trait Implementations

impl Clone for Color

fn clone(&self) -> Color

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Color

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for Color

Available on crate feature serde only.

fn deserialize<D>(deserializer: D) -> Result<Color, D::Error>

where D: Deserializer<'de>,

Deserialize from a token string: #rgb/#rrggbb, a named color (case-insensitive), or indexed:N.

impl From<[u8; 3]> for Color

fn from([r, g, b]: [u8; 3]) -> Color

Construct an Color::Rgb from an [r, g, b] array.

impl From<(u8, u8, u8)> for Color

fn from((r, g, b): (u8, u8, u8)) -> Color

Construct an Color::Rgb from an (r, g, b) tuple.

impl From<u32> for Color

fn from(value: u32) -> Color

Construct an Color::Rgb from a packed 0xRRGGBB integer.

The high byte (alpha / 0xAA______) is ignored.

Example

use slt::Color;

assert_eq!(Color::from(0xff6b6b), Color::Rgb(255, 107, 107));

impl FromStr for Color

fn from_str(s: &str) -> Result<Color, ColorParseError>

Parse a color from a string.

Accepts hex (#rgb, #rrggbb, or bare rrggbb / rgb without the leading #) and case-insensitive named colors ("red", "lightblue", "darkgray", "reset", …).

Errors

Returns ColorParseError when the input matches no known form: ColorParseError::InvalidLength for a hex token of the wrong length, ColorParseError::InvalidHexDigit for non-hex digits in a #-prefixed token, and ColorParseError::Unknown otherwise.

Example

use slt::Color;

assert_eq!("#ff6b6b".parse::<Color>(), Ok(Color::Rgb(255, 107, 107)));
assert_eq!("ff6b6b".parse::<Color>(), Ok(Color::Rgb(255, 107, 107)));
assert_eq!("#abc".parse::<Color>(), Ok(Color::Rgb(170, 187, 204)));
assert_eq!("cyan".parse::<Color>(), Ok(Color::Cyan));
assert!("nope".parse::<Color>().is_err());

type Err = ColorParseError

The associated error which can be returned from parsing.

impl Hash for Color

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for Color

fn eq(&self, other: &Color) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Serialize for Color

Available on crate feature serde only.

fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>

where S: Serializer,

Serialize as a human-friendly string token (#rrggbb, a named color, or indexed:N) so theme files stay hand-editable and round-trip.

impl Copy for Color

impl Eq for Color

impl StructuralPartialEq for Color