chromashift/
lch.rs

1use crate::{Alpha, Lab, Number, ToAlpha};
2use core::fmt;
3
4/// A cylindrical colour space representing within the CIE colour space.
5/// The components are:
6/// - Lightness / Luminance - a number between 0.0 and 100.0
7/// - Chroma - a number between 0.0 and 150.0
8/// - Hue - a number between 0.0 and 360.0
9/// - Alpha - a number between 0.0 and 100.0
10#[derive(Debug, Clone, Copy, PartialEq)]
11pub struct Lch {
12	pub lightness: f64,
13	pub chroma: f64,
14	pub hue: f64,
15	pub alpha: f32,
16}
17
18impl Lch {
19	pub fn new(lightness: f64, chroma: f64, hue: f64, alpha: f32) -> Self {
20		Self { lightness, chroma, hue: hue.rem_euclid(360.0), alpha: alpha.clamp(0.0, 100.0) }
21	}
22}
23
24impl ToAlpha for Lch {
25	fn to_alpha(&self) -> f32 {
26		self.alpha
27	}
28}
29
30impl fmt::Display for Lch {
31	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
32		let Self { lightness, chroma, hue, alpha } = *self;
33		write!(f, "lch({} {} {}{})", Number(lightness), Number(chroma), Number(hue), Alpha(alpha))
34	}
35}
36
37impl From<Lab> for Lch {
38	fn from(value: Lab) -> Self {
39		let Lab { lightness, a, b, alpha } = value;
40		let chroma = (a * a + b * b).sqrt();
41		let hue = b.atan2(a).to_degrees();
42		let hue = if chroma <= 0.0015 {
43			0.0
44		} else if hue < 0.0 {
45			hue + 360.0
46		} else {
47			hue
48		};
49		Lch::new(lightness, chroma, hue, alpha)
50	}
51}
52
53impl From<Lch> for Lab {
54	fn from(value: Lch) -> Self {
55		let Lch { lightness, chroma, hue, alpha } = value;
56		let h_rad = hue.to_radians();
57		Lab::new(lightness, chroma * h_rad.cos(), chroma * h_rad.sin(), alpha)
58	}
59}
chromashift/lch.rs

chromashift/
lch.rs
