chromashift/
hwb.rs

1use crate::{Hsv, 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 fmt::Display for Hwb {
30	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
31		let Self { hue, whiteness, blackness, alpha } = self;
32		write!(
33			f,
34			"hwb({} {} {}",
35			round_dp(*hue as f64, 2),
36			round_dp(*whiteness as f64, 3),
37			round_dp(*blackness as f64, 3)
38		)?;
39		if *alpha < 100.0 {
40			write!(f, " / {}", round_dp(*alpha as f64, 2))?;
41		}
42		write!(f, ")")
43	}
44}
45
46impl From<Hsv> for Hwb {
47	fn from(value: Hsv) -> Self {
48		let Hsv { hue, saturation, value, alpha } = value;
49		let s = saturation / 100.0;
50		let v = value / 100.0;
51		let whiteness = (1.0 - s) * v;
52		let blackness = 1.0 - v;
53		Hwb::new(hue, whiteness * 100.0, blackness * 100.0, alpha)
54	}
55}
56
57impl From<Hwb> for Hsv {
58	fn from(value: Hwb) -> Self {
59		let Hwb { hue, whiteness, blackness, alpha } = value;
60		let w = whiteness / 100.0;
61		let b = blackness / 100.0;
62		let sum = w + b;
63		let (s, v) = if sum >= 1.0 {
64			(0.0, w / sum)
65		} else {
66			let v = 1.0 - b;
67			let s = if v == 0.0 { 0.0 } else { 1.0 - w / v };
68			(s, v)
69		};
70		Hsv::new(hue, s * 100.0, v * 100.0, alpha)
71	}
72}
chromashift/hwb.rs

chromashift/
hwb.rs
