cosmic_theme/
steps.rs

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1use std::num::NonZeroUsize;
2
3use almost::equal;
4use palette::{convert::FromColorUnclamped, ClampAssign, FromColor, Lch, Oklcha, Srgb, Srgba};
5
6/// Get an array of 100 colors with a specific hue and chroma
7/// over the full range of lightness.
8/// Colors which are not valid Srgba will fallback to a color with the nearest valid chroma.
9pub fn steps<C>(c: C, len: NonZeroUsize) -> Vec<Srgba>
10where
11    Oklcha: FromColor<C>,
12{
13    let mut c = Oklcha::from_color(c);
14    let mut steps = Vec::with_capacity(len.get());
15
16    for i in 0..len.get() {
17        let lightness = i as f32 / (len.get() - 1) as f32;
18        c.l = lightness;
19        steps.push(oklch_to_srgba_nearest_chroma(c))
20    }
21    steps
22}
23
24/// get the index for a new color some steps away from a base color
25pub fn get_index(base_index: usize, steps: usize, step_len: usize, is_dark: bool) -> Option<usize> {
26    if is_dark {
27        base_index.checked_add(steps)
28    } else {
29        base_index.checked_sub(steps)
30    }
31    .filter(|i| *i < step_len)
32}
33
34/// get surface color given a base and some steps
35pub fn get_surface_color(
36    base_index: usize,
37    steps: usize,
38    step_array: &[Srgba],
39    mut is_dark: bool,
40    fallback: &Srgba,
41) -> Srgba {
42    assert!(step_array.len() == 100);
43
44    is_dark = is_dark || base_index < 91;
45
46    *get_index(base_index, steps, step_array.len(), is_dark)
47        .and_then(|i| step_array.get(i))
48        .unwrap_or(fallback)
49}
50
51/// get surface color given a base and some steps
52#[must_use]
53pub fn get_small_widget_color(
54    base_index: usize,
55    steps: usize,
56    step_array: &[Srgba],
57    fallback: &Srgba,
58) -> Srgba {
59    assert!(step_array.len() == 100);
60
61    let is_dark = base_index <= 40 || (base_index > 51 && base_index < 65);
62
63    let res = *get_index(base_index, steps, step_array.len(), is_dark)
64        .and_then(|i| step_array.get(i))
65        .unwrap_or(fallback);
66
67    let mut lch = Lch::from_color(res);
68    if lch.chroma / Lch::<f32>::max_chroma() > 0.03 {
69        lch.chroma = 0.03 * Lch::<f32>::max_chroma();
70        lch.clamp_assign();
71        Srgba::from_color(lch)
72    } else {
73        res
74    }
75}
76
77/// get text color given a base background color
78pub fn get_text(
79    base_index: usize,
80    step_array: &[Srgba],
81    fallback: &Srgba,
82    tint_array: Option<&[Srgba]>,
83) -> Srgba {
84    assert!(step_array.len() == 100);
85    let step_array = if let Some(tint_array) = tint_array {
86        assert!(tint_array.len() == 100);
87        tint_array
88    } else {
89        step_array
90    };
91
92    let is_dark = base_index < 60;
93
94    let index = get_index(base_index, 70, step_array.len(), is_dark)
95        .or_else(|| get_index(base_index, 50, step_array.len(), is_dark))
96        .unwrap_or_else(|| if is_dark { 99 } else { 0 });
97
98    *step_array.get(index).unwrap_or(fallback)
99}
100
101/// get the index into the steps array for a given color
102/// the index is the lightness value of the color converted to Oklcha, scaled to the range [0, 100]
103pub fn color_index<C>(c: C, array_len: usize) -> usize
104where
105    Oklcha: FromColor<C>,
106{
107    let c = Oklcha::from_color(c);
108    ((c.l * array_len as f32).round() as usize).clamp(0, array_len - 1)
109}
110
111/// find the nearest chroma which makes our color a valid color in Srgba
112pub fn oklch_to_srgba_nearest_chroma(mut c: Oklcha) -> Srgba {
113    let mut r_chroma = c.chroma;
114    let mut l_chroma = 0.0;
115    // exit early if we found it right away
116    let mut new_c = Srgba::from_color_unclamped(c);
117
118    if is_valid_srgb(new_c) {
119        new_c.clamp_assign();
120        return new_c;
121    }
122
123    // is this an excessive depth to search?
124    for _ in 0..64 {
125        let new_c = Srgba::from_color_unclamped(c);
126        if is_valid_srgb(new_c) {
127            l_chroma = c.chroma;
128            c.chroma = (c.chroma + r_chroma) / 2.0;
129        } else {
130            r_chroma = c.chroma;
131            c.chroma = (c.chroma + l_chroma) / 2.0;
132        }
133    }
134    Srgba::from_color(c)
135}
136
137/// checks that the color is valid srgb
138pub fn is_valid_srgb(c: Srgba) -> bool {
139    (equal(c.red, Srgb::max_red()) || (c.red >= Srgb::min_red() && c.red <= Srgb::max_red()))
140        && (equal(c.blue, Srgb::max_blue())
141            || (c.blue >= Srgb::min_blue() && c.blue <= Srgb::max_blue()))
142        && (equal(c.green, Srgb::max_green())
143            || (c.green >= Srgb::min_green() && c.green <= Srgb::max_green()))
144}
145
146#[cfg(test)]
147mod tests {
148    use almost::equal;
149    use palette::{OklabHue, Srgba};
150
151    use super::{is_valid_srgb, oklch_to_srgba_nearest_chroma};
152
153    #[test]
154    fn test_valid_check() {
155        assert!(is_valid_srgb(Srgba::new(1.0, 1.0, 1.0, 1.0)));
156        assert!(is_valid_srgb(Srgba::new(0.0, 0.0, 0.0, 1.0)));
157        assert!(is_valid_srgb(Srgba::new(0.5, 0.5, 0.5, 1.0)));
158        assert!(!is_valid_srgb(Srgba::new(-0.1, 0.0, 0.0, 1.0)));
159        assert!(!is_valid_srgb(Srgba::new(0.0, -0.1, 0.0, 1.0)));
160        assert!(!is_valid_srgb(Srgba::new(-0.0, 0.0, -0.1, 1.0)));
161        assert!(!is_valid_srgb(Srgba::new(-100.1, 0.0, 0.0, 1.0)));
162        assert!(!is_valid_srgb(Srgba::new(0.0, -100.1, 0.0, 1.0)));
163        assert!(!is_valid_srgb(Srgba::new(-0.0, 0.0, -100.1, 1.0)));
164        assert!(!is_valid_srgb(Srgba::new(1.1, 0.0, 0.0, 1.0)));
165        assert!(!is_valid_srgb(Srgba::new(0.0, 1.1, 0.0, 1.0)));
166        assert!(!is_valid_srgb(Srgba::new(-0.0, 0.0, 1.1, 1.0)));
167        assert!(!is_valid_srgb(Srgba::new(100.1, 0.0, 0.0, 1.0)));
168        assert!(!is_valid_srgb(Srgba::new(0.0, 100.1, 0.0, 1.0)));
169        assert!(!is_valid_srgb(Srgba::new(-0.0, 0.0, 100.1, 1.0)));
170    }
171
172    #[test]
173    fn test_conversion_boundaries() {
174        let c1 = palette::Oklcha::new(0.0, 0.288, OklabHue::from_degrees(0.0), 1.0);
175        let srgb = oklch_to_srgba_nearest_chroma(c1);
176        equal(srgb.red, 0.0);
177        equal(srgb.blue, 0.0);
178        equal(srgb.green, 0.0);
179
180        let c1 = palette::Oklcha::new(1.0, 0.288, OklabHue::from_degrees(0.0), 1.0);
181        let srgb = oklch_to_srgba_nearest_chroma(c1);
182
183        equal(srgb.red, 1.0);
184        equal(srgb.blue, 1.0);
185        equal(srgb.green, 1.0);
186    }
187
188    #[test]
189    fn test_conversion_colors() {
190        let c1 = palette::Oklcha::new(0.4608, 0.11111, OklabHue::new(57.31), 1.0);
191        let srgb = oklch_to_srgba_nearest_chroma(c1).into_format::<u8, u8>();
192        assert!(srgb.red == 133);
193        assert!(srgb.green == 69);
194        assert!(srgb.blue == 0);
195
196        let c1 = palette::Oklcha::new(0.30, 0.08, OklabHue::new(35.0), 1.0);
197        let srgb = oklch_to_srgba_nearest_chroma(c1).into_format::<u8, u8>();
198        assert!(srgb.red == 78);
199        assert!(srgb.green == 27);
200        assert!(srgb.blue == 15);
201
202        let c1 = palette::Oklcha::new(0.757, 0.146, OklabHue::new(301.2), 1.0);
203        let srgb = oklch_to_srgba_nearest_chroma(c1).into_format::<u8, u8>();
204        assert!(srgb.red == 192);
205        assert!(srgb.green == 153);
206        assert!(srgb.blue == 253);
207    }
208
209    #[test]
210    fn test_conversion_fallback_colors() {
211        let c1 = palette::Oklcha::new(0.70, 0.284, OklabHue::new(35.0), 1.0);
212        let srgb = oklch_to_srgba_nearest_chroma(c1).into_format::<u8, u8>();
213        assert!(srgb.red == 255);
214        assert!(srgb.green == 103);
215        assert!(srgb.blue == 65);
216
217        let c1 = palette::Oklcha::new(0.757, 0.239, OklabHue::new(301.2), 1.0);
218        let srgb = oklch_to_srgba_nearest_chroma(c1).into_format::<u8, u8>();
219        assert!(srgb.red == 193);
220        assert!(srgb.green == 152);
221        assert!(srgb.blue == 255);
222
223        let c1 = palette::Oklcha::new(0.163, 0.333, OklabHue::new(141.0), 1.0);
224        let srgb = oklch_to_srgba_nearest_chroma(c1).into_format::<u8, u8>();
225        assert!(srgb.red == 1);
226        assert!(srgb.green == 19);
227        assert!(srgb.blue == 0);
228    }
229}
cosmic_theme/steps.rs

cosmic_theme/
steps.rs
