Rgb

An sRGB color with 8 bits per channel.

Built with Rgb::new or parsed from text with Rgb::parse (#rgb, #rrggbb, rgb(r, g, b) or one of the 17 basic CSS color names). Display writes the #rrggbb form.

Import

use helpers4::color::Rgb;

Cargo feature color (enabled by default). To compile only this module:

cargo add helpers4 --no-default-features --features color

or in Cargo.toml:

[dependencies]
helpers4 = { version = "0.0.6", default-features = false, features = ["color"] }

Definition

pub struct Rgb { /* private fields */ }

Examples

use helpers4::color::Rgb;

let orange = Rgb::parse("#ff8800")?;
assert_eq!((orange.r(), orange.g(), orange.b()), (255, 136, 0));
assert_eq!(orange.to_string(), "#ff8800");
assert_eq!(Rgb::parse("rgb(0, 128, 255)")?, Rgb::new(0, 128, 255));
assert_eq!(Rgb::parse("Red")?.to_hex(), "#ff0000");

Methods

new

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

Builds a color from its three channels.

Parameters

Parameter	Type	Description
r	u8	Red, 0..=255.
g	u8	Green, 0..=255.
b	u8	Blue, 0..=255.

Returns

Self — The color.

parse

pub fn parse(text: &str) -> Result<Self, ParseColorError>

Parses a color written as #rgb, #rrggbb, rgb(r, g, b) or a basic CSS color name.

Surrounding whitespace is ignored, hex digits and names are case-insensitive. #rgb repeats each digit (#f80 is #ff8800). In rgb(...) the three whole numbers (0..=255) may be separated by commas or spaces. The names are the 17 basic CSS keywords: black, silver, gray, white, maroon, red, purple, fuchsia, green, lime, olive, yellow, navy, blue, teal, aqua and orange.

Parameters

Parameter	Type	Description
text	&str	The color to parse.

Returns

Result<Self, ParseColorError>

Errors

A ParseColorError for an empty text, a # color with a bad length or digit, a malformed or out-of-range rgb(...), or an unknown name.

r

pub fn r(self) -> u8

The red channel.

Returns

u8 — A value from 0 to 255.

g

pub fn g(self) -> u8

The green channel.

Returns

u8 — A value from 0 to 255.

b

pub fn b(self) -> u8

The blue channel.

Returns

u8 — A value from 0 to 255.

to_hex

pub fn to_hex(self) -> String

The #rrggbb form, in lower case.

Returns

String — For instance "#ff8800".

to_hsl

pub fn to_hsl(self) -> Hsl

The same color as hue, saturation and lightness.

Returns

Hsl — The Hsl value. Converting it back with Hsl::to_rgb gives this color again.

luminance

pub fn luminance(self) -> f64

The WCAG relative luminance: 0.0 for black, 1.0 for white.

The channels are linearized from sRGB and weighted by how bright the eye finds each (0.2126 red, 0.7152 green, 0.0722 blue).

Returns

f64 — A value from 0.0 to 1.0.

lighten

pub fn lighten(self, amount: f64) -> Self

Moves the color towards white.

Parameters

Parameter	Type	Description
amount	f64	How far to go, from 0.0 (unchanged) to 1.0 (white); out-of-range values are clamped.

Returns

Self — The lighter color.

darken

pub fn darken(self, amount: f64) -> Self

Moves the color towards black.

Parameters

Parameter	Type	Description
amount	f64	How far to go, from 0.0 (unchanged) to 1.0 (black); out-of-range values are clamped.

Returns

Self — The darker color.

Error type: ParseColorError

Why a string could not be parsed as a color.

use helpers4::color::ParseColorError;

#[non_exhaustive]
pub enum ParseColorError {
    /// The string is empty or only whitespace.
    Empty,
    /// A `#` color that does not have 3 or 6 hexadecimal digits.
    InvalidLength {
        /// The number of characters after the `#`.
        length: usize,
    },
    /// A character that is not a hexadecimal digit.
    InvalidDigit {
        /// Byte offset of the character in the input.
        index: usize,
    },
    /// An `rgb(...)` that does not hold exactly three whole numbers.
    InvalidFunction,
    /// A channel above 255 in `rgb(...)`.
    OutOfRange,
    /// Neither a `#hex` color, an `rgb(...)`, nor a known color name.
    UnknownName,
}

Source

src/color/rgb.rs