native_theme/
color.rs

1// Rgba color type with custom hex serde
2
3use serde::de;
4use serde::{Deserialize, Deserializer, Serialize, Serializer};
5use std::fmt;
6use std::str::FromStr;
7
8/// An sRGB color with alpha, stored as four u8 components.
9///
10/// All values are in the sRGB color space. When parsing hex strings,
11/// alpha defaults to 255 (fully opaque) if omitted.
12///
13/// # Hex Format
14///
15/// Supports parsing from and displaying as hex strings:
16/// - `#RGB` / `RGB` -- 3-digit shorthand (each digit doubled: `#abc` -> `#aabbcc`)
17/// - `#RGBA` / `RGBA` -- 4-digit shorthand with alpha
18/// - `#RRGGBB` / `RRGGBB` -- standard 6-digit hex
19/// - `#RRGGBBAA` / `RRGGBBAA` -- 8-digit hex with alpha
20///
21/// Display outputs lowercase hex: `#rrggbb` when alpha is 255,
22/// `#rrggbbaa` otherwise.
23///
24/// # Examples
25///
26/// ```
27/// use native_theme::Rgba;
28///
29/// // Create an opaque color
30/// let blue = Rgba::rgb(0, 120, 215);
31/// assert_eq!(blue.a, 255);
32///
33/// // Parse from a hex string
34/// let parsed: Rgba = "#3daee9".parse().unwrap();
35/// assert_eq!(parsed.r, 61);
36///
37/// // Convert to f32 array for toolkit interop
38/// let arr = Rgba::rgb(255, 0, 0).to_f32_array();
39/// assert_eq!(arr, [1.0, 0.0, 0.0, 1.0]);
40/// ```
41#[derive(Clone, Copy, Debug, Default, PartialEq, Eq, Hash)]
42pub struct Rgba {
43    /// Red component (0-255).
44    pub r: u8,
45    /// Green component (0-255).
46    pub g: u8,
47    /// Blue component (0-255).
48    pub b: u8,
49    /// Alpha component (0-255, where 255 is fully opaque).
50    pub a: u8,
51}
52
53impl Rgba {
54    /// Create an opaque color (alpha = 255).
55    pub const fn rgb(r: u8, g: u8, b: u8) -> Self {
56        Self { r, g, b, a: 255 }
57    }
58
59    /// Create a color with explicit alpha.
60    #[allow(clippy::self_named_constructors)]
61    pub const fn rgba(r: u8, g: u8, b: u8, a: u8) -> Self {
62        Self { r, g, b, a }
63    }
64
65    /// Create a color from floating-point components in the 0.0..=1.0 range.
66    ///
67    /// Values are clamped to 0.0..=1.0 before conversion.
68    pub fn from_f32(r: f32, g: f32, b: f32, a: f32) -> Self {
69        Self {
70            r: (r.clamp(0.0, 1.0) * 255.0).round() as u8,
71            g: (g.clamp(0.0, 1.0) * 255.0).round() as u8,
72            b: (b.clamp(0.0, 1.0) * 255.0).round() as u8,
73            a: (a.clamp(0.0, 1.0) * 255.0).round() as u8,
74        }
75    }
76
77    /// Convert to `[r, g, b, a]` in the 0.0..=1.0 range (for toolkit interop).
78    pub fn to_f32_array(&self) -> [f32; 4] {
79        [
80            self.r as f32 / 255.0,
81            self.g as f32 / 255.0,
82            self.b as f32 / 255.0,
83            self.a as f32 / 255.0,
84        ]
85    }
86
87    /// Convert to `(r, g, b, a)` tuple in the 0.0..=1.0 range.
88    pub fn to_f32_tuple(&self) -> (f32, f32, f32, f32) {
89        (
90            self.r as f32 / 255.0,
91            self.g as f32 / 255.0,
92            self.b as f32 / 255.0,
93            self.a as f32 / 255.0,
94        )
95    }
96}
97
98impl fmt::Display for Rgba {
99    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
100        if self.a == 255 {
101            write!(f, "#{:02x}{:02x}{:02x}", self.r, self.g, self.b)
102        } else {
103            write!(
104                f,
105                "#{:02x}{:02x}{:02x}{:02x}",
106                self.r, self.g, self.b, self.a
107            )
108        }
109    }
110}
111
112/// Error returned when parsing a hex color string fails.
113///
114/// Wraps a human-readable message describing the failure cause.
115/// Implements [`std::error::Error`] so it works with `?` in functions
116/// returning `Box<dyn Error>`.
117#[derive(Debug, Clone)]
118pub struct ParseColorError(String);
119
120impl fmt::Display for ParseColorError {
121    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
122        f.write_str(&self.0)
123    }
124}
125
126impl std::error::Error for ParseColorError {}
127
128impl FromStr for Rgba {
129    type Err = ParseColorError;
130
131    fn from_str(s: &str) -> Result<Self, Self::Err> {
132        let hex = s.strip_prefix('#').unwrap_or(s);
133
134        if hex.is_empty() {
135            return Err(ParseColorError("empty hex color string".into()));
136        }
137
138        match hex.len() {
139            // #RGB shorthand: each digit doubled (e.g., 'a' -> 0xaa = a * 17)
140            3 => {
141                let r = u8::from_str_radix(&hex[0..1], 16)
142                    .map_err(|e| ParseColorError(format!("invalid red component: {e}")))?;
143                let g = u8::from_str_radix(&hex[1..2], 16)
144                    .map_err(|e| ParseColorError(format!("invalid green component: {e}")))?;
145                let b = u8::from_str_radix(&hex[2..3], 16)
146                    .map_err(|e| ParseColorError(format!("invalid blue component: {e}")))?;
147                Ok(Rgba::rgb(r * 17, g * 17, b * 17))
148            }
149            // #RGBA shorthand
150            4 => {
151                let r = u8::from_str_radix(&hex[0..1], 16)
152                    .map_err(|e| ParseColorError(format!("invalid red component: {e}")))?;
153                let g = u8::from_str_radix(&hex[1..2], 16)
154                    .map_err(|e| ParseColorError(format!("invalid green component: {e}")))?;
155                let b = u8::from_str_radix(&hex[2..3], 16)
156                    .map_err(|e| ParseColorError(format!("invalid blue component: {e}")))?;
157                let a = u8::from_str_radix(&hex[3..4], 16)
158                    .map_err(|e| ParseColorError(format!("invalid alpha component: {e}")))?;
159                Ok(Rgba::rgba(r * 17, g * 17, b * 17, a * 17))
160            }
161            // #RRGGBB
162            6 => {
163                let r = u8::from_str_radix(&hex[0..2], 16)
164                    .map_err(|e| ParseColorError(format!("invalid red component: {e}")))?;
165                let g = u8::from_str_radix(&hex[2..4], 16)
166                    .map_err(|e| ParseColorError(format!("invalid green component: {e}")))?;
167                let b = u8::from_str_radix(&hex[4..6], 16)
168                    .map_err(|e| ParseColorError(format!("invalid blue component: {e}")))?;
169                Ok(Rgba::rgb(r, g, b))
170            }
171            // #RRGGBBAA
172            8 => {
173                let r = u8::from_str_radix(&hex[0..2], 16)
174                    .map_err(|e| ParseColorError(format!("invalid red component: {e}")))?;
175                let g = u8::from_str_radix(&hex[2..4], 16)
176                    .map_err(|e| ParseColorError(format!("invalid green component: {e}")))?;
177                let b = u8::from_str_radix(&hex[4..6], 16)
178                    .map_err(|e| ParseColorError(format!("invalid blue component: {e}")))?;
179                let a = u8::from_str_radix(&hex[6..8], 16)
180                    .map_err(|e| ParseColorError(format!("invalid alpha component: {e}")))?;
181                Ok(Rgba::rgba(r, g, b, a))
182            }
183            other => Err(ParseColorError(format!(
184                "invalid hex color length {other}: expected 3, 4, 6, or 8 hex digits"
185            ))),
186        }
187    }
188}
189
190impl Serialize for Rgba {
191    fn serialize<S: Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> {
192        serializer.serialize_str(&self.to_string())
193    }
194}
195
196impl<'de> Deserialize<'de> for Rgba {
197    fn deserialize<D: Deserializer<'de>>(deserializer: D) -> Result<Self, D::Error> {
198        let s = String::deserialize(deserializer)?;
199        Rgba::from_str(&s).map_err(de::Error::custom)
200    }
201}
202
203#[cfg(test)]
204#[allow(clippy::unwrap_used, clippy::expect_used)]
205mod tests {
206    use super::*;
207
208    // === Constructor tests ===
209
210    #[test]
211    fn rgb_constructor_sets_alpha_255() {
212        let c = Rgba::rgb(61, 174, 233);
213        assert_eq!(
214            c,
215            Rgba {
216                r: 61,
217                g: 174,
218                b: 233,
219                a: 255
220            }
221        );
222    }
223
224    #[test]
225    fn rgba_constructor_sets_all_fields() {
226        let c = Rgba::rgba(61, 174, 233, 128);
227        assert_eq!(
228            c,
229            Rgba {
230                r: 61,
231                g: 174,
232                b: 233,
233                a: 128
234            }
235        );
236    }
237
238    // === FromStr parsing tests ===
239
240    #[test]
241    fn parse_6_digit_hex_with_hash() {
242        let c: Rgba = "#3daee9".parse().unwrap();
243        assert_eq!(c, Rgba::rgb(61, 174, 233));
244    }
245
246    #[test]
247    fn parse_8_digit_hex_with_hash() {
248        let c: Rgba = "#3daee980".parse().unwrap();
249        assert_eq!(c, Rgba::rgba(61, 174, 233, 128));
250    }
251
252    #[test]
253    fn parse_6_digit_hex_without_hash() {
254        let c: Rgba = "3daee9".parse().unwrap();
255        assert_eq!(c, Rgba::rgb(61, 174, 233));
256    }
257
258    #[test]
259    fn parse_3_digit_shorthand() {
260        let c: Rgba = "#abc".parse().unwrap();
261        assert_eq!(c, Rgba::rgb(0xaa, 0xbb, 0xcc));
262    }
263
264    #[test]
265    fn parse_4_digit_shorthand() {
266        let c: Rgba = "#abcd".parse().unwrap();
267        assert_eq!(c, Rgba::rgba(0xaa, 0xbb, 0xcc, 0xdd));
268    }
269
270    #[test]
271    fn parse_uppercase_hex() {
272        let c: Rgba = "#AABBCC".parse().unwrap();
273        assert_eq!(c, Rgba::rgb(0xaa, 0xbb, 0xcc));
274    }
275
276    #[test]
277    fn parse_empty_string_is_error() {
278        assert!("".parse::<Rgba>().is_err());
279    }
280
281    #[test]
282    fn parse_invalid_hex_chars_is_error() {
283        assert!("#gggggg".parse::<Rgba>().is_err());
284    }
285
286    #[test]
287    fn parse_invalid_length_5_chars_is_error() {
288        assert!("#12345".parse::<Rgba>().is_err());
289    }
290
291    // === Display tests ===
292
293    #[test]
294    fn display_omits_alpha_when_255() {
295        assert_eq!(Rgba::rgb(61, 174, 233).to_string(), "#3daee9");
296    }
297
298    #[test]
299    fn display_includes_alpha_when_not_255() {
300        assert_eq!(Rgba::rgba(61, 174, 233, 128).to_string(), "#3daee980");
301    }
302
303    // === Serde round-trip tests ===
304
305    #[test]
306    fn serde_json_round_trip() {
307        let c = Rgba::rgb(61, 174, 233);
308        let json = serde_json::to_string(&c).unwrap();
309        assert_eq!(json, "\"#3daee9\"");
310        let deserialized: Rgba = serde_json::from_str(&json).unwrap();
311        assert_eq!(deserialized, c);
312    }
313
314    #[test]
315    fn serde_toml_round_trip() {
316        #[derive(Debug, PartialEq, Serialize, Deserialize)]
317        struct Wrapper {
318            color: Rgba,
319        }
320        let w = Wrapper {
321            color: Rgba::rgba(61, 174, 233, 128),
322        };
323        let toml_str = toml::to_string(&w).unwrap();
324        let deserialized: Wrapper = toml::from_str(&toml_str).unwrap();
325        assert_eq!(deserialized, w);
326    }
327
328    // === to_f32_array tests ===
329
330    #[test]
331    fn to_f32_array_black() {
332        let arr = Rgba::rgb(0, 0, 0).to_f32_array();
333        assert_eq!(arr, [0.0, 0.0, 0.0, 1.0]);
334    }
335
336    #[test]
337    fn to_f32_array_white_transparent() {
338        let arr = Rgba::rgba(255, 255, 255, 0).to_f32_array();
339        assert_eq!(arr, [1.0, 1.0, 1.0, 0.0]);
340    }
341
342    // === Trait tests ===
343
344    #[test]
345    fn rgba_is_copy() {
346        let a = Rgba::rgb(1, 2, 3);
347        let b = a; // Copy
348        assert_eq!(a, b); // a still accessible after copy
349    }
350
351    #[test]
352    fn rgba_default_is_transparent_black() {
353        let d = Rgba::default();
354        assert_eq!(
355            d,
356            Rgba {
357                r: 0,
358                g: 0,
359                b: 0,
360                a: 0
361            }
362        );
363    }
364
365    #[test]
366    fn rgba_is_hash() {
367        use std::collections::HashSet;
368        let mut set = HashSet::new();
369        set.insert(Rgba::rgb(1, 2, 3));
370        assert!(set.contains(&Rgba::rgb(1, 2, 3)));
371    }
372
373    // === from_f32 tests ===
374
375    #[test]
376    fn from_f32_basic() {
377        let c = Rgba::from_f32(1.0, 0.5, 0.0, 1.0);
378        assert_eq!(c.r, 255);
379        assert_eq!(c.g, 128); // 0.5 * 255 = 127.5, round to 128
380        assert_eq!(c.b, 0);
381        assert_eq!(c.a, 255);
382    }
383
384    #[test]
385    fn from_f32_clamps_out_of_range() {
386        let c = Rgba::from_f32(-0.5, 1.5, 0.0, 0.0);
387        assert_eq!(c.r, 0);
388        assert_eq!(c.g, 255);
389    }
390
391    // === to_f32_tuple test ===
392
393    #[test]
394    fn to_f32_tuple_matches_array() {
395        let c = Rgba::rgb(128, 64, 32);
396        let arr = c.to_f32_array();
397        let tup = c.to_f32_tuple();
398        assert_eq!(tup, (arr[0], arr[1], arr[2], arr[3]));
399    }
400}
native_theme/color.rs

native_theme/
color.rs
