Struct Rgb 

pub struct Rgb {
    pub r: u8,
    pub g: u8,
    pub b: u8,
}

A 24-bit sRGB colour.

Fields

r: u8

Red channel.

g: u8

Green channel.

b: u8

Blue channel.

Implementations

impl Rgb

pub const fn new(r: u8, g: u8, b: u8) -> Self

Creates a colour from its channels.

pub fn parse_hex(text: &str) -> Option<Self>

Parses #RRGGBB or #RGB, in either letter case.

pub fn mix(self, other: Self, t: f32) -> Self

Blends towards other: t = 0 gives self, t = 1 gives other. t is clamped to 0..=1.

pub fn relative_luminance(self) -> f64

WCAG relative luminance, from 0 (black) to 1 (white).

pub fn contrast_ratio(self, other: Self) -> f64

WCAG contrast ratio between two colours, from 1 to 21.

pub fn oklab(self) -> [f64; 3]

The colour in the OKLab perceptual space as [L, a, b].

pub fn perceptual_distance(self, other: Self) -> f64

Euclidean distance in OKLab. Around 0.02 is barely visible; 0.10 reads as a clearly different colour.

pub fn to_ansi256(self) -> u8

Nearest entry of the xterm 256-colour palette (indices 16..=255).

pub fn to_ansi256_text(self, bg: Self) -> u8

The entry of the xterm 256-colour palette this colour takes as text on bg.

Mostly the nearest entry, as Rgb::to_ansi256 gives it. Faint text, such as a page dimmed behind a dialog, can land on an entry that no longer reads on its background’s — under 1.6:1 in the WCAG ratio, where a glyph starts to disappear; it then takes the entry closest to it in OKLab that still keeps 1.6:1, so faint text stays faint rather than vanishing. Text drawn in the very colour of its background is left as it is, since that is a fill rather than something to read.

pub fn to_ansi16(self) -> u8

Nearest of the 16 standard terminal colours (xterm defaults), by distance alone.

This is the plain reduction: on a dark screen every surface tone lands on black here. What a sixteen-colour frame actually shows is Rgb::to_ansi16_on for backgrounds and Rgb::to_ansi16_text for text, which keep lifted surfaces and faint text apart from the ground.

pub fn from_ansi16(index: u8) -> Self

The colour of entry index of the 16 standard terminal colours, as xterm shows them by default; an index past 15 gives the last entry, white. A terminal may be themed differently, so these are the colours a reduction can count on, not the ones a person necessarily sees.

pub fn from_ansi256(index: u8) -> Self

The colour of entry index of the xterm 256-colour palette as xterm shows it by default: the 16 standard colours as Rgb::from_ansi16 gives them, then the 6×6×6 colour cube, then the 24 greys from 8 to 238.

pub fn to_ansi16_on(self, ground: Self) -> u8

The entry of the 16 standard colours this colour takes as a background on a screen whose ground is ground (the theme’s canvas).

Mostly the nearest entry, as Rgb::to_ansi16 gives it. The exception is a tone the eye tells from the ground in full colour — at least 0.05 away in OKLab, the same distance under which a floating surface melts into the ground — that would still land on the ground’s own entry: it moves one step along the grey ladder black, bright black, white, bright white, away from the ground. On a dark theme the ground stays black and raised surfaces, tab strips and dialogs become bright black; on a light theme they step down from bright white to white. Panels a shade off the ground stay on it, as in full colour they barely differ.

pub fn to_ansi16_text(self, bg: Self, ground: Self) -> u8

The entry of the 16 standard colours this colour takes as text on bg, on a screen whose ground is ground.

Both colours are reduced as Rgb::to_ansi16_on does. When the text would then no longer read on its background — under 1.6:1 in the WCAG ratio, which is where a glyph starts to disappear — it takes the quietest grey that still keeps 3:1 against it: faint text stays faint rather than vanishing. On bright black that is white, on black bright black. Text drawn in the very colour of its background is left as it is, since that is a fill rather than something to read.

Trait Implementations

impl Clone for Rgb

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for Rgb

impl Debug for Rgb

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

Formats the value using the given formatter.

impl Display for Rgb

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

Formats the value using the given formatter.

impl Eq for Rgb

impl From<Rgb> for CellColor

fn from(color: Rgb) -> Self

A hard-coded colour, written #RRGGBB.

impl Hash for Rgb

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 Rgb

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for Rgb