chromashift/
hwb.rs

1use crate::{Hsv, ToAlpha, round_dp};
2use core::fmt;
3
4/// An colour represented as Hue, Whiteness, and Blackness expressed in the sRGB colour space.
5/// The components are:
6/// - Hue - a number between 0.0 and 360.0
7/// - Whiteness - a number between 0.0 and 100.0
8/// - Blackness - a number between 0.0 and 100.0
9/// - Alpha - a number between 0.0 and 100.0
10#[derive(Debug, Clone, Copy, PartialEq)]
11pub struct Hwb {
12	pub hue: f32,
13	pub whiteness: f32,
14	pub blackness: f32,
15	pub alpha: f32,
16}
17
18impl Hwb {
19	pub fn new(hue: f32, whiteness: f32, blackness: f32, alpha: f32) -> Self {
20		Self {
21			hue: hue.rem_euclid(360.0),
22			whiteness: whiteness.clamp(0.0, 100.0),
23			blackness: blackness.clamp(0.0, 100.0),
24			alpha: alpha.clamp(0.0, 100.0),
25		}
26	}
27}
28
29impl ToAlpha for Hwb {
30	fn to_alpha(&self) -> f32 {
31		self.alpha
32	}
33}
34
35impl fmt::Display for Hwb {
36	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
37		let Self { hue, whiteness, blackness, alpha } = self;
38		write!(
39			f,
40			"hwb({} {} {}",
41			round_dp(*hue as f64, 2),
42			round_dp(*whiteness as f64, 3),
43			round_dp(*blackness as f64, 3)
44		)?;
45		if *alpha < 100.0 {
46			write!(f, " / {}", round_dp(*alpha as f64, 2))?;
47		}
48		write!(f, ")")
49	}
50}
51
52impl From<Hsv> for Hwb {
53	fn from(value: Hsv) -> Self {
54		let Hsv { hue, saturation, value, alpha } = value;
55		let s = saturation / 100.0;
56		let v = value / 100.0;
57		let whiteness = (1.0 - s) * v;
58		let blackness = 1.0 - v;
59		Hwb::new(hue, whiteness * 100.0, blackness * 100.0, alpha)
60	}
61}
62
63impl From<Hwb> for Hsv {
64	fn from(value: Hwb) -> Self {
65		let Hwb { hue, whiteness, blackness, alpha } = value;
66		let w = whiteness / 100.0;
67		let b = blackness / 100.0;
68		let sum = w + b;
69		let (s, v) = if sum >= 1.0 {
70			(0.0, w / sum)
71		} else {
72			let v = 1.0 - b;
73			let s = if v == 0.0 { 0.0 } else { 1.0 - w / v };
74			(s, v)
75		};
76		Hsv::new(hue, s * 100.0, v * 100.0, alpha)
77	}
78}
chromashift/hwb.rs

chromashift/
hwb.rs
