1use anyhow::bail;
2use serde::de::{self, Deserialize, Deserializer, Visitor};
3use std::fmt;
4
5/// Convert an RGB hex color code number to a color type
6pub fn rgb<C: From<Rgba>>(hex: u32) -> C {
7 let r = ((hex >> 16) & 0xFF) as f32 / 255.0;
8 let g = ((hex >> 8) & 0xFF) as f32 / 255.0;
9 let b = (hex & 0xFF) as f32 / 255.0;
10 Rgba { r, g, b, a: 1.0 }.into()
11}
12
13/// Convert an RGBA hex color code number to [`Rgba`]
14pub fn rgba(hex: u32) -> Rgba {
15 let r = ((hex >> 24) & 0xFF) as f32 / 255.0;
16 let g = ((hex >> 16) & 0xFF) as f32 / 255.0;
17 let b = ((hex >> 8) & 0xFF) as f32 / 255.0;
18 let a = (hex & 0xFF) as f32 / 255.0;
19 Rgba { r, g, b, a }
20}
21
22/// An RGBA color
23#[derive(PartialEq, Clone, Copy, Default)]
24pub struct Rgba {
25 /// The red component of the color, in the range 0.0 to 1.0
26 pub r: f32,
27 /// The green component of the color, in the range 0.0 to 1.0
28 pub g: f32,
29 /// The blue component of the color, in the range 0.0 to 1.0
30 pub b: f32,
31 /// The alpha component of the color, in the range 0.0 to 1.0
32 pub a: f32,
33}
34
35impl fmt::Debug for Rgba {
36 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
37 write!(f, "rgba({:#010x})", u32::from(*self))
38 }
39}
40
41impl Rgba {
42 /// Create a new [`Rgba`] color by blending this and another color together
43 /// TODO!(docs): find the source for this algorithm
44 pub fn blend(&self, other: Rgba) -> Self {
45 if other.a >= 1.0 {
46 other
47 } else if other.a <= 0.0 {
48 return *self;
49 } else {
50 return Rgba {
51 r: (self.r * (1.0 - other.a)) + (other.r * other.a),
52 g: (self.g * (1.0 - other.a)) + (other.g * other.a),
53 b: (self.b * (1.0 - other.a)) + (other.b * other.a),
54 a: self.a,
55 };
56 }
57 }
58}
59
60impl From<Rgba> for u32 {
61 fn from(rgba: Rgba) -> Self {
62 let r = (rgba.r * 255.0) as u32;
63 let g = (rgba.g * 255.0) as u32;
64 let b = (rgba.b * 255.0) as u32;
65 let a = (rgba.a * 255.0) as u32;
66 (r << 24) | (g << 16) | (b << 8) | a
67 }
68}
69
70struct RgbaVisitor;
71
72impl<'de> Visitor<'de> for RgbaVisitor {
73 type Value = Rgba;
74
75 fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
76 formatter.write_str("a string in the format #rrggbb or #rrggbbaa")
77 }
78
79 fn visit_str<E: de::Error>(self, value: &str) -> Result<Rgba, E> {
80 Rgba::try_from(value).map_err(E::custom)
81 }
82}
83
84impl<'de> Deserialize<'de> for Rgba {
85 fn deserialize<D: Deserializer<'de>>(deserializer: D) -> Result<Self, D::Error> {
86 deserializer.deserialize_str(RgbaVisitor)
87 }
88}
89
90impl From<Hsla> for Rgba {
91 fn from(color: Hsla) -> Self {
92 let h = color.h;
93 let s = color.s;
94 let l = color.l;
95
96 let c = (1.0 - (2.0 * l - 1.0).abs()) * s;
97 let x = c * (1.0 - ((h * 6.0) % 2.0 - 1.0).abs());
98 let m = l - c / 2.0;
99 let cm = c + m;
100 let xm = x + m;
101
102 let (r, g, b) = match (h * 6.0).floor() as i32 {
103 0 | 6 => (cm, xm, m),
104 1 => (xm, cm, m),
105 2 => (m, cm, xm),
106 3 => (m, xm, cm),
107 4 => (xm, m, cm),
108 _ => (cm, m, xm),
109 };
110
111 Rgba {
112 r,
113 g,
114 b,
115 a: color.a,
116 }
117 }
118}
119
120impl TryFrom<&'_ str> for Rgba {
121 type Error = anyhow::Error;
122
123 fn try_from(value: &'_ str) -> Result<Self, Self::Error> {
124 const RGB: usize = "rgb".len();
125 const RGBA: usize = "rgba".len();
126 const RRGGBB: usize = "rrggbb".len();
127 const RRGGBBAA: usize = "rrggbbaa".len();
128
129 const EXPECTED_FORMATS: &str = "Expected #rgb, #rgba, #rrggbb, or #rrggbbaa";
130
131 let Some(("", hex)) = value.trim().split_once('#') else {
132 bail!("invalid RGBA hex color: '{value}'. {EXPECTED_FORMATS}");
133 };
134
135 let (r, g, b, a) = match hex.len() {
136 RGB | RGBA => {
137 let r = u8::from_str_radix(&hex[0..1], 16)?;
138 let g = u8::from_str_radix(&hex[1..2], 16)?;
139 let b = u8::from_str_radix(&hex[2..3], 16)?;
140 let a = if hex.len() == RGBA {
141 u8::from_str_radix(&hex[3..4], 16)?
142 } else {
143 0xf
144 };
145
146 /// Duplicates a given hex digit.
147 /// E.g., `0xf` -> `0xff`.
148 const fn duplicate(value: u8) -> u8 {
149 value << 4 | value
150 }
151
152 (duplicate(r), duplicate(g), duplicate(b), duplicate(a))
153 }
154 RRGGBB | RRGGBBAA => {
155 let r = u8::from_str_radix(&hex[0..2], 16)?;
156 let g = u8::from_str_radix(&hex[2..4], 16)?;
157 let b = u8::from_str_radix(&hex[4..6], 16)?;
158 let a = if hex.len() == RRGGBBAA {
159 u8::from_str_radix(&hex[6..8], 16)?
160 } else {
161 0xff
162 };
163 (r, g, b, a)
164 }
165 _ => bail!("invalid RGBA hex color: '{value}'. {EXPECTED_FORMATS}"),
166 };
167
168 Ok(Rgba {
169 r: r as f32 / 255.,
170 g: g as f32 / 255.,
171 b: b as f32 / 255.,
172 a: a as f32 / 255.,
173 })
174 }
175}
176
177/// An HSLA color
178#[derive(Default, Copy, Clone, Debug)]
179#[repr(C)]
180pub struct Hsla {
181 /// Hue, in a range from 0 to 1
182 pub h: f32,
183
184 /// Saturation, in a range from 0 to 1
185 pub s: f32,
186
187 /// Lightness, in a range from 0 to 1
188 pub l: f32,
189
190 /// Alpha, in a range from 0 to 1
191 pub a: f32,
192}
193
194impl PartialEq for Hsla {
195 fn eq(&self, other: &Self) -> bool {
196 self.h
197 .total_cmp(&other.h)
198 .then(self.s.total_cmp(&other.s))
199 .then(self.l.total_cmp(&other.l).then(self.a.total_cmp(&other.a)))
200 .is_eq()
201 }
202}
203
204impl PartialOrd for Hsla {
205 fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
206 Some(self.cmp(other))
207 }
208}
209
210impl Ord for Hsla {
211 fn cmp(&self, other: &Self) -> std::cmp::Ordering {
212 self.h
213 .total_cmp(&other.h)
214 .then(self.s.total_cmp(&other.s))
215 .then(self.l.total_cmp(&other.l).then(self.a.total_cmp(&other.a)))
216 }
217}
218
219impl Eq for Hsla {}
220
221/// Construct an [`Hsla`] object from plain values
222pub fn hsla(h: f32, s: f32, l: f32, a: f32) -> Hsla {
223 Hsla {
224 h: h.clamp(0., 1.),
225 s: s.clamp(0., 1.),
226 l: l.clamp(0., 1.),
227 a: a.clamp(0., 1.),
228 }
229}
230
231/// Pure black in [`Hsla`]
232pub fn black() -> Hsla {
233 Hsla {
234 h: 0.,
235 s: 0.,
236 l: 0.,
237 a: 1.,
238 }
239}
240
241/// Transparent black in [`Hsla`]
242pub fn transparent_black() -> Hsla {
243 Hsla {
244 h: 0.,
245 s: 0.,
246 l: 0.,
247 a: 0.,
248 }
249}
250
251/// Pure white in [`Hsla`]
252pub fn white() -> Hsla {
253 Hsla {
254 h: 0.,
255 s: 0.,
256 l: 1.,
257 a: 1.,
258 }
259}
260
261/// The color red in [`Hsla`]
262pub fn red() -> Hsla {
263 Hsla {
264 h: 0.,
265 s: 1.,
266 l: 0.5,
267 a: 1.,
268 }
269}
270
271/// The color blue in [`Hsla`]
272pub fn blue() -> Hsla {
273 Hsla {
274 h: 0.6,
275 s: 1.,
276 l: 0.5,
277 a: 1.,
278 }
279}
280
281/// The color green in [`Hsla`]
282pub fn green() -> Hsla {
283 Hsla {
284 h: 0.33,
285 s: 1.,
286 l: 0.5,
287 a: 1.,
288 }
289}
290
291/// The color yellow in [`Hsla`]
292pub fn yellow() -> Hsla {
293 Hsla {
294 h: 0.16,
295 s: 1.,
296 l: 0.5,
297 a: 1.,
298 }
299}
300
301impl Hsla {
302 /// Converts this HSLA color to an RGBA color.
303 pub fn to_rgb(self) -> Rgba {
304 self.into()
305 }
306
307 /// The color red
308 pub fn red() -> Self {
309 red()
310 }
311
312 /// The color green
313 pub fn green() -> Self {
314 green()
315 }
316
317 /// The color blue
318 pub fn blue() -> Self {
319 blue()
320 }
321
322 /// The color black
323 pub fn black() -> Self {
324 black()
325 }
326
327 /// The color white
328 pub fn white() -> Self {
329 white()
330 }
331
332 /// The color transparent black
333 pub fn transparent_black() -> Self {
334 transparent_black()
335 }
336
337 /// Returns true if the HSLA color is fully transparent, false otherwise.
338 pub fn is_transparent(&self) -> bool {
339 self.a == 0.0
340 }
341
342 /// Blends `other` on top of `self` based on `other`'s alpha value. The resulting color is a combination of `self`'s and `other`'s colors.
343 ///
344 /// If `other`'s alpha value is 1.0 or greater, `other` color is fully opaque, thus `other` is returned as the output color.
345 /// If `other`'s alpha value is 0.0 or less, `other` color is fully transparent, thus `self` is returned as the output color.
346 /// Else, the output color is calculated as a blend of `self` and `other` based on their weighted alpha values.
347 ///
348 /// Assumptions:
349 /// - Alpha values are contained in the range [0, 1], with 1 as fully opaque and 0 as fully transparent.
350 /// - The relative contributions of `self` and `other` is based on `self`'s alpha value (`self.a`) and `other`'s alpha value (`other.a`), `self` contributing `self.a * (1.0 - other.a)` and `other` contributing its own alpha value.
351 /// - RGB color components are contained in the range [0, 1].
352 /// - If `self` and `other` colors are out of the valid range, the blend operation's output and behavior is undefined.
353 pub fn blend(self, other: Hsla) -> Hsla {
354 let alpha = other.a;
355
356 if alpha >= 1.0 {
357 other
358 } else if alpha <= 0.0 {
359 return self;
360 } else {
361 let converted_self = Rgba::from(self);
362 let converted_other = Rgba::from(other);
363 let blended_rgb = converted_self.blend(converted_other);
364 return Hsla::from(blended_rgb);
365 }
366 }
367
368 /// Returns a new HSLA color with the same hue, and lightness, but with no saturation.
369 pub fn grayscale(&self) -> Self {
370 Hsla {
371 h: self.h,
372 s: 0.,
373 l: self.l,
374 a: self.a,
375 }
376 }
377
378 /// Fade out the color by a given factor. This factor should be between 0.0 and 1.0.
379 /// Where 0.0 will leave the color unchanged, and 1.0 will completely fade out the color.
380 pub fn fade_out(&mut self, factor: f32) {
381 self.a *= 1.0 - factor.clamp(0., 1.);
382 }
383}
384
385impl From<Rgba> for Hsla {
386 fn from(color: Rgba) -> Self {
387 let r = color.r;
388 let g = color.g;
389 let b = color.b;
390
391 let max = r.max(g.max(b));
392 let min = r.min(g.min(b));
393 let delta = max - min;
394
395 let l = (max + min) / 2.0;
396 let s = if l == 0.0 || l == 1.0 {
397 0.0
398 } else if l < 0.5 {
399 delta / (2.0 * l)
400 } else {
401 delta / (2.0 - 2.0 * l)
402 };
403
404 let h = if delta == 0.0 {
405 0.0
406 } else if max == r {
407 ((g - b) / delta).rem_euclid(6.0) / 6.0
408 } else if max == g {
409 ((b - r) / delta + 2.0) / 6.0
410 } else {
411 ((r - g) / delta + 4.0) / 6.0
412 };
413
414 Hsla {
415 h,
416 s,
417 l,
418 a: color.a,
419 }
420 }
421}
422
423impl<'de> Deserialize<'de> for Hsla {
424 fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
425 where
426 D: Deserializer<'de>,
427 {
428 // First, deserialize it into Rgba
429 let rgba = Rgba::deserialize(deserializer)?;
430
431 // Then, use the From<Rgba> for Hsla implementation to convert it
432 Ok(Hsla::from(rgba))
433 }
434}
435
436#[cfg(test)]
437mod tests {
438 use serde_json::json;
439
440 use super::*;
441
442 #[test]
443 fn test_deserialize_three_value_hex_to_rgba() {
444 let actual: Rgba = serde_json::from_value(json!("#f09")).unwrap();
445
446 assert_eq!(actual, rgba(0xff0099ff))
447 }
448
449 #[test]
450 fn test_deserialize_four_value_hex_to_rgba() {
451 let actual: Rgba = serde_json::from_value(json!("#f09f")).unwrap();
452
453 assert_eq!(actual, rgba(0xff0099ff))
454 }
455
456 #[test]
457 fn test_deserialize_six_value_hex_to_rgba() {
458 let actual: Rgba = serde_json::from_value(json!("#ff0099")).unwrap();
459
460 assert_eq!(actual, rgba(0xff0099ff))
461 }
462
463 #[test]
464 fn test_deserialize_eight_value_hex_to_rgba() {
465 let actual: Rgba = serde_json::from_value(json!("#ff0099ff")).unwrap();
466
467 assert_eq!(actual, rgba(0xff0099ff))
468 }
469
470 #[test]
471 fn test_deserialize_eight_value_hex_with_padding_to_rgba() {
472 let actual: Rgba = serde_json::from_value(json!(" #f5f5f5ff ")).unwrap();
473
474 assert_eq!(actual, rgba(0xf5f5f5ff))
475 }
476
477 #[test]
478 fn test_deserialize_eight_value_hex_with_mixed_case_to_rgba() {
479 let actual: Rgba = serde_json::from_value(json!("#DeAdbEeF")).unwrap();
480
481 assert_eq!(actual, rgba(0xdeadbeef))
482 }
483}