color.rs

  1use anyhow::{Context as _, bail};
  2use schemars::{JsonSchema, json_schema};
  3use serde::{
  4    Deserialize, Deserializer, Serialize, Serializer,
  5    de::{self, Visitor},
  6};
  7use std::borrow::Cow;
  8use std::{
  9    fmt::{self, Display, Formatter},
 10    hash::{Hash, Hasher},
 11};
 12
 13/// Convert an RGB hex color code number to a color type
 14pub fn rgb(hex: u32) -> Rgba {
 15    let [_, r, g, b] = hex.to_be_bytes().map(|b| (b as f32) / 255.0);
 16    Rgba { r, g, b, a: 1.0 }
 17}
 18
 19/// Convert an RGBA hex color code number to [`Rgba`]
 20pub fn rgba(hex: u32) -> Rgba {
 21    let [r, g, b, a] = hex.to_be_bytes().map(|b| (b as f32) / 255.0);
 22    Rgba { r, g, b, a }
 23}
 24
 25/// Swap from RGBA with premultiplied alpha to BGRA
 26pub(crate) fn swap_rgba_pa_to_bgra(color: &mut [u8]) {
 27    color.swap(0, 2);
 28    if color[3] > 0 {
 29        let a = color[3] as f32 / 255.;
 30        color[0] = (color[0] as f32 / a) as u8;
 31        color[1] = (color[1] as f32 / a) as u8;
 32        color[2] = (color[2] as f32 / a) as u8;
 33    }
 34}
 35
 36/// An RGBA color
 37#[derive(PartialEq, Clone, Copy, Default)]
 38#[repr(C)]
 39pub struct Rgba {
 40    /// The red component of the color, in the range 0.0 to 1.0
 41    pub r: f32,
 42    /// The green component of the color, in the range 0.0 to 1.0
 43    pub g: f32,
 44    /// The blue component of the color, in the range 0.0 to 1.0
 45    pub b: f32,
 46    /// The alpha component of the color, in the range 0.0 to 1.0
 47    pub a: f32,
 48}
 49
 50impl fmt::Debug for Rgba {
 51    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 52        write!(f, "rgba({:#010x})", u32::from(*self))
 53    }
 54}
 55
 56impl Rgba {
 57    /// Create a new [`Rgba`] color by blending this and another color together
 58    pub fn blend(&self, other: Rgba) -> Self {
 59        if other.a >= 1.0 {
 60            other
 61        } else if other.a <= 0.0 {
 62            *self
 63        } else {
 64            Rgba {
 65                r: (self.r * (1.0 - other.a)) + (other.r * other.a),
 66                g: (self.g * (1.0 - other.a)) + (other.g * other.a),
 67                b: (self.b * (1.0 - other.a)) + (other.b * other.a),
 68                a: self.a,
 69            }
 70        }
 71    }
 72}
 73
 74impl From<Rgba> for u32 {
 75    fn from(rgba: Rgba) -> Self {
 76        let r = (rgba.r * 255.0) as u32;
 77        let g = (rgba.g * 255.0) as u32;
 78        let b = (rgba.b * 255.0) as u32;
 79        let a = (rgba.a * 255.0) as u32;
 80        (r << 24) | (g << 16) | (b << 8) | a
 81    }
 82}
 83
 84struct RgbaVisitor;
 85
 86impl Visitor<'_> for RgbaVisitor {
 87    type Value = Rgba;
 88
 89    fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
 90        formatter.write_str("a string in the format #rrggbb or #rrggbbaa")
 91    }
 92
 93    fn visit_str<E: de::Error>(self, value: &str) -> Result<Rgba, E> {
 94        Rgba::try_from(value).map_err(E::custom)
 95    }
 96}
 97
 98impl JsonSchema for Rgba {
 99    fn schema_name() -> Cow<'static, str> {
100        "Rgba".into()
101    }
102
103    fn json_schema(_generator: &mut schemars::SchemaGenerator) -> schemars::Schema {
104        json_schema!({
105            "type": "string",
106            "pattern": "^#([0-9a-fA-F]{3}|[0-9a-fA-F]{4}|[0-9a-fA-F]{6}|[0-9a-fA-F]{8})$"
107        })
108    }
109}
110
111impl<'de> Deserialize<'de> for Rgba {
112    fn deserialize<D: Deserializer<'de>>(deserializer: D) -> Result<Self, D::Error> {
113        deserializer.deserialize_str(RgbaVisitor)
114    }
115}
116
117impl Serialize for Rgba {
118    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
119    where
120        S: Serializer,
121    {
122        let r = (self.r * 255.0).round() as u8;
123        let g = (self.g * 255.0).round() as u8;
124        let b = (self.b * 255.0).round() as u8;
125        let a = (self.a * 255.0).round() as u8;
126
127        let s = format!("#{r:02x}{g:02x}{b:02x}{a:02x}");
128        serializer.serialize_str(&s)
129    }
130}
131
132impl From<Hsla> for Rgba {
133    fn from(color: Hsla) -> Self {
134        let h = color.h;
135        let s = color.s;
136        let l = color.l;
137
138        let c = (1.0 - (2.0 * l - 1.0).abs()) * s;
139        let x = c * (1.0 - ((h * 6.0) % 2.0 - 1.0).abs());
140        let m = l - c / 2.0;
141        let cm = c + m;
142        let xm = x + m;
143
144        let (r, g, b) = match (h * 6.0).floor() as i32 {
145            0 | 6 => (cm, xm, m),
146            1 => (xm, cm, m),
147            2 => (m, cm, xm),
148            3 => (m, xm, cm),
149            4 => (xm, m, cm),
150            _ => (cm, m, xm),
151        };
152
153        Rgba {
154            r,
155            g,
156            b,
157            a: color.a,
158        }
159    }
160}
161
162impl TryFrom<&'_ str> for Rgba {
163    type Error = anyhow::Error;
164
165    fn try_from(value: &'_ str) -> Result<Self, Self::Error> {
166        const RGB: usize = "rgb".len();
167        const RGBA: usize = "rgba".len();
168        const RRGGBB: usize = "rrggbb".len();
169        const RRGGBBAA: usize = "rrggbbaa".len();
170
171        const EXPECTED_FORMATS: &str = "Expected #rgb, #rgba, #rrggbb, or #rrggbbaa";
172        const INVALID_UNICODE: &str = "invalid unicode characters in color";
173
174        let Some(("", hex)) = value.trim().split_once('#') else {
175            bail!("invalid RGBA hex color: '{value}'. {EXPECTED_FORMATS}");
176        };
177
178        let (r, g, b, a) = match hex.len() {
179            RGB | RGBA => {
180                let r = u8::from_str_radix(
181                    hex.get(0..1).with_context(|| {
182                        format!("{INVALID_UNICODE}: r component of #rgb/#rgba for value: '{value}'")
183                    })?,
184                    16,
185                )?;
186                let g = u8::from_str_radix(
187                    hex.get(1..2).with_context(|| {
188                        format!("{INVALID_UNICODE}: g component of #rgb/#rgba for value: '{value}'")
189                    })?,
190                    16,
191                )?;
192                let b = u8::from_str_radix(
193                    hex.get(2..3).with_context(|| {
194                        format!("{INVALID_UNICODE}: b component of #rgb/#rgba for value: '{value}'")
195                    })?,
196                    16,
197                )?;
198                let a = if hex.len() == RGBA {
199                    u8::from_str_radix(
200                        hex.get(3..4).with_context(|| {
201                            format!("{INVALID_UNICODE}: a component of #rgba for value: '{value}'")
202                        })?,
203                        16,
204                    )?
205                } else {
206                    0xf
207                };
208
209                /// Duplicates a given hex digit.
210                /// E.g., `0xf` -> `0xff`.
211                const fn duplicate(value: u8) -> u8 {
212                    (value << 4) | value
213                }
214
215                (duplicate(r), duplicate(g), duplicate(b), duplicate(a))
216            }
217            RRGGBB | RRGGBBAA => {
218                let r = u8::from_str_radix(
219                    hex.get(0..2).with_context(|| {
220                        format!(
221                            "{}: r component of #rrggbb/#rrggbbaa for value: '{}'",
222                            INVALID_UNICODE, value
223                        )
224                    })?,
225                    16,
226                )?;
227                let g = u8::from_str_radix(
228                    hex.get(2..4).with_context(|| {
229                        format!(
230                            "{INVALID_UNICODE}: g component of #rrggbb/#rrggbbaa for value: '{value}'"
231                        )
232                    })?,
233                    16,
234                )?;
235                let b = u8::from_str_radix(
236                    hex.get(4..6).with_context(|| {
237                        format!(
238                            "{INVALID_UNICODE}: b component of #rrggbb/#rrggbbaa for value: '{value}'"
239                        )
240                    })?,
241                    16,
242                )?;
243                let a = if hex.len() == RRGGBBAA {
244                    u8::from_str_radix(
245                        hex.get(6..8).with_context(|| {
246                            format!(
247                                "{INVALID_UNICODE}: a component of #rrggbbaa for value: '{value}'"
248                            )
249                        })?,
250                        16,
251                    )?
252                } else {
253                    0xff
254                };
255                (r, g, b, a)
256            }
257            _ => bail!("invalid RGBA hex color: '{value}'. {EXPECTED_FORMATS}"),
258        };
259
260        Ok(Rgba {
261            r: r as f32 / 255.,
262            g: g as f32 / 255.,
263            b: b as f32 / 255.,
264            a: a as f32 / 255.,
265        })
266    }
267}
268
269/// An HSLA color
270#[derive(Default, Copy, Clone, Debug)]
271#[repr(C)]
272pub struct Hsla {
273    /// Hue, in a range from 0 to 1
274    pub h: f32,
275
276    /// Saturation, in a range from 0 to 1
277    pub s: f32,
278
279    /// Lightness, in a range from 0 to 1
280    pub l: f32,
281
282    /// Alpha, in a range from 0 to 1
283    pub a: f32,
284}
285
286impl PartialEq for Hsla {
287    fn eq(&self, other: &Self) -> bool {
288        self.h
289            .total_cmp(&other.h)
290            .then(self.s.total_cmp(&other.s))
291            .then(self.l.total_cmp(&other.l).then(self.a.total_cmp(&other.a)))
292            .is_eq()
293    }
294}
295
296impl PartialOrd for Hsla {
297    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
298        Some(self.cmp(other))
299    }
300}
301
302impl Ord for Hsla {
303    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
304        self.h
305            .total_cmp(&other.h)
306            .then(self.s.total_cmp(&other.s))
307            .then(self.l.total_cmp(&other.l).then(self.a.total_cmp(&other.a)))
308    }
309}
310
311impl Eq for Hsla {}
312
313impl Hash for Hsla {
314    fn hash<H: Hasher>(&self, state: &mut H) {
315        state.write_u32(u32::from_be_bytes(self.h.to_be_bytes()));
316        state.write_u32(u32::from_be_bytes(self.s.to_be_bytes()));
317        state.write_u32(u32::from_be_bytes(self.l.to_be_bytes()));
318        state.write_u32(u32::from_be_bytes(self.a.to_be_bytes()));
319    }
320}
321
322impl Display for Hsla {
323    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
324        write!(
325            f,
326            "hsla({:.2}, {:.2}%, {:.2}%, {:.2})",
327            self.h * 360.,
328            self.s * 100.,
329            self.l * 100.,
330            self.a
331        )
332    }
333}
334
335/// Construct an [`Hsla`] object from plain values
336pub fn hsla(h: f32, s: f32, l: f32, a: f32) -> Hsla {
337    Hsla {
338        h: h.clamp(0., 1.),
339        s: s.clamp(0., 1.),
340        l: l.clamp(0., 1.),
341        a: a.clamp(0., 1.),
342    }
343}
344
345/// Pure black in [`Hsla`]
346pub const fn black() -> Hsla {
347    Hsla {
348        h: 0.,
349        s: 0.,
350        l: 0.,
351        a: 1.,
352    }
353}
354
355/// Transparent black in [`Hsla`]
356pub const fn transparent_black() -> Hsla {
357    Hsla {
358        h: 0.,
359        s: 0.,
360        l: 0.,
361        a: 0.,
362    }
363}
364
365/// Transparent black in [`Hsla`]
366pub const fn transparent_white() -> Hsla {
367    Hsla {
368        h: 0.,
369        s: 0.,
370        l: 1.,
371        a: 0.,
372    }
373}
374
375/// Opaque grey in [`Hsla`], values will be clamped to the range [0, 1]
376pub fn opaque_grey(lightness: f32, opacity: f32) -> Hsla {
377    Hsla {
378        h: 0.,
379        s: 0.,
380        l: lightness.clamp(0., 1.),
381        a: opacity.clamp(0., 1.),
382    }
383}
384
385/// Pure white in [`Hsla`]
386pub const fn white() -> Hsla {
387    Hsla {
388        h: 0.,
389        s: 0.,
390        l: 1.,
391        a: 1.,
392    }
393}
394
395/// The color red in [`Hsla`]
396pub const fn red() -> Hsla {
397    Hsla {
398        h: 0.,
399        s: 1.,
400        l: 0.5,
401        a: 1.,
402    }
403}
404
405/// The color blue in [`Hsla`]
406pub const fn blue() -> Hsla {
407    Hsla {
408        h: 0.6666666667,
409        s: 1.,
410        l: 0.5,
411        a: 1.,
412    }
413}
414
415/// The color green in [`Hsla`]
416pub const fn green() -> Hsla {
417    Hsla {
418        h: 0.3333333333,
419        s: 1.,
420        l: 0.25,
421        a: 1.,
422    }
423}
424
425/// The color yellow in [`Hsla`]
426pub const fn yellow() -> Hsla {
427    Hsla {
428        h: 0.1666666667,
429        s: 1.,
430        l: 0.5,
431        a: 1.,
432    }
433}
434
435impl Hsla {
436    /// Converts this HSLA color to an RGBA color.
437    pub fn to_rgb(self) -> Rgba {
438        self.into()
439    }
440
441    /// The color red
442    pub const fn red() -> Self {
443        red()
444    }
445
446    /// The color green
447    pub const fn green() -> Self {
448        green()
449    }
450
451    /// The color blue
452    pub const fn blue() -> Self {
453        blue()
454    }
455
456    /// The color black
457    pub const fn black() -> Self {
458        black()
459    }
460
461    /// The color white
462    pub const fn white() -> Self {
463        white()
464    }
465
466    /// The color transparent black
467    pub const fn transparent_black() -> Self {
468        transparent_black()
469    }
470
471    /// Returns true if the HSLA color is fully transparent, false otherwise.
472    pub fn is_transparent(&self) -> bool {
473        self.a == 0.0
474    }
475
476    /// Returns true if the HSLA color is fully opaque, false otherwise.
477    pub fn is_opaque(&self) -> bool {
478        self.a == 1.0
479    }
480
481    /// 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.
482    ///
483    /// If `other`'s alpha value is 1.0 or greater, `other` color is fully opaque, thus `other` is returned as the output color.
484    /// If `other`'s alpha value is 0.0 or less, `other` color is fully transparent, thus `self` is returned as the output color.
485    /// Else, the output color is calculated as a blend of `self` and `other` based on their weighted alpha values.
486    ///
487    /// Assumptions:
488    /// - Alpha values are contained in the range [0, 1], with 1 as fully opaque and 0 as fully transparent.
489    /// - 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.
490    /// - RGB color components are contained in the range [0, 1].
491    /// - If `self` and `other` colors are out of the valid range, the blend operation's output and behavior is undefined.
492    pub fn blend(self, other: Hsla) -> Hsla {
493        let alpha = other.a;
494
495        if alpha >= 1.0 {
496            other
497        } else if alpha <= 0.0 {
498            self
499        } else {
500            let converted_self = Rgba::from(self);
501            let converted_other = Rgba::from(other);
502            let blended_rgb = converted_self.blend(converted_other);
503            Hsla::from(blended_rgb)
504        }
505    }
506
507    /// Returns a new HSLA color with the same hue, and lightness, but with no saturation.
508    pub fn grayscale(&self) -> Self {
509        Hsla {
510            h: self.h,
511            s: 0.,
512            l: self.l,
513            a: self.a,
514        }
515    }
516
517    /// Fade out the color by a given factor. This factor should be between 0.0 and 1.0.
518    /// Where 0.0 will leave the color unchanged, and 1.0 will completely fade out the color.
519    pub fn fade_out(&mut self, factor: f32) {
520        self.a *= 1.0 - factor.clamp(0., 1.);
521    }
522
523    /// Multiplies the alpha value of the color by a given factor
524    /// and returns a new HSLA color.
525    ///
526    /// Useful for transforming colors with dynamic opacity,
527    /// like a color from an external source.
528    ///
529    /// Example:
530    /// ```
531    /// let color = gpui::red();
532    /// let faded_color = color.opacity(0.5);
533    /// assert_eq!(faded_color.a, 0.5);
534    /// ```
535    ///
536    /// This will return a red color with half the opacity.
537    ///
538    /// Example:
539    /// ```
540    /// let color = hlsa(0.7, 1.0, 0.5, 0.7); // A saturated blue
541    /// let faded_color = color.opacity(0.16);
542    /// assert_eq!(faded_color.a, 0.112);
543    /// ```
544    ///
545    /// This will return a blue color with around ~10% opacity,
546    /// suitable for an element's hover or selected state.
547    ///
548    pub fn opacity(&self, factor: f32) -> Self {
549        Hsla {
550            h: self.h,
551            s: self.s,
552            l: self.l,
553            a: self.a * factor.clamp(0., 1.),
554        }
555    }
556
557    /// Returns a new HSLA color with the same hue, saturation,
558    /// and lightness, but with a new alpha value.
559    ///
560    /// Example:
561    /// ```
562    /// let color = gpui::red();
563    /// let red_color = color.alpha(0.25);
564    /// assert_eq!(red_color.a, 0.25);
565    /// ```
566    ///
567    /// This will return a red color with half the opacity.
568    ///
569    /// Example:
570    /// ```
571    /// let color = hsla(0.7, 1.0, 0.5, 0.7); // A saturated blue
572    /// let faded_color = color.alpha(0.25);
573    /// assert_eq!(faded_color.a, 0.25);
574    /// ```
575    ///
576    /// This will return a blue color with 25% opacity.
577    pub fn alpha(&self, a: f32) -> Self {
578        Hsla {
579            h: self.h,
580            s: self.s,
581            l: self.l,
582            a: a.clamp(0., 1.),
583        }
584    }
585}
586
587impl From<Rgba> for Hsla {
588    fn from(color: Rgba) -> Self {
589        let r = color.r;
590        let g = color.g;
591        let b = color.b;
592
593        let max = r.max(g.max(b));
594        let min = r.min(g.min(b));
595        let delta = max - min;
596
597        let l = (max + min) / 2.0;
598        let s = if l == 0.0 || l == 1.0 {
599            0.0
600        } else if l < 0.5 {
601            delta / (2.0 * l)
602        } else {
603            delta / (2.0 - 2.0 * l)
604        };
605
606        let h = if delta == 0.0 {
607            0.0
608        } else if max == r {
609            ((g - b) / delta).rem_euclid(6.0) / 6.0
610        } else if max == g {
611            ((b - r) / delta + 2.0) / 6.0
612        } else {
613            ((r - g) / delta + 4.0) / 6.0
614        };
615
616        Hsla {
617            h,
618            s,
619            l,
620            a: color.a,
621        }
622    }
623}
624
625impl JsonSchema for Hsla {
626    fn schema_name() -> Cow<'static, str> {
627        Rgba::schema_name()
628    }
629
630    fn json_schema(generator: &mut schemars::SchemaGenerator) -> schemars::Schema {
631        Rgba::json_schema(generator)
632    }
633}
634
635impl Serialize for Hsla {
636    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
637    where
638        S: Serializer,
639    {
640        Rgba::from(*self).serialize(serializer)
641    }
642}
643
644impl<'de> Deserialize<'de> for Hsla {
645    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
646    where
647        D: Deserializer<'de>,
648    {
649        Ok(Rgba::deserialize(deserializer)?.into())
650    }
651}
652
653#[derive(Debug, Clone, Copy, PartialEq, Serialize, Deserialize, JsonSchema)]
654#[repr(C)]
655pub(crate) enum BackgroundTag {
656    Solid = 0,
657    LinearGradient = 1,
658    PatternSlash = 2,
659}
660
661/// A color space for color interpolation.
662///
663/// References:
664/// - <https://developer.mozilla.org/en-US/docs/Web/CSS/color-interpolation-method>
665/// - <https://www.w3.org/TR/css-color-4/#typedef-color-space>
666#[derive(Debug, Clone, Copy, PartialEq, Default, Serialize, Deserialize, JsonSchema)]
667#[repr(C)]
668pub enum ColorSpace {
669    #[default]
670    /// The sRGB color space.
671    Srgb = 0,
672    /// The Oklab color space.
673    Oklab = 1,
674}
675
676impl Display for ColorSpace {
677    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
678        match self {
679            ColorSpace::Srgb => write!(f, "sRGB"),
680            ColorSpace::Oklab => write!(f, "Oklab"),
681        }
682    }
683}
684
685/// A background color, which can be either a solid color or a linear gradient.
686#[derive(Clone, Copy, PartialEq, Serialize, Deserialize, JsonSchema)]
687#[repr(C)]
688pub struct Background {
689    pub(crate) tag: BackgroundTag,
690    pub(crate) color_space: ColorSpace,
691    pub(crate) solid: Hsla,
692    pub(crate) gradient_angle_or_pattern_height: f32,
693    pub(crate) colors: [LinearColorStop; 2],
694    /// Padding for alignment for repr(C) layout.
695    pad: u32,
696}
697
698impl std::fmt::Debug for Background {
699    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
700        match self.tag {
701            BackgroundTag::Solid => write!(f, "Solid({:?})", self.solid),
702            BackgroundTag::LinearGradient => {
703                write!(
704                    f,
705                    "LinearGradient({}, {:?}, {:?})",
706                    self.gradient_angle_or_pattern_height, self.colors[0], self.colors[1]
707                )
708            }
709            BackgroundTag::PatternSlash => {
710                write!(
711                    f,
712                    "PatternSlash({:?}, {})",
713                    self.solid, self.gradient_angle_or_pattern_height
714                )
715            }
716        }
717    }
718}
719
720impl Eq for Background {}
721impl Default for Background {
722    fn default() -> Self {
723        Self {
724            tag: BackgroundTag::Solid,
725            solid: Hsla::default(),
726            color_space: ColorSpace::default(),
727            gradient_angle_or_pattern_height: 0.0,
728            colors: [LinearColorStop::default(), LinearColorStop::default()],
729            pad: 0,
730        }
731    }
732}
733
734/// Creates a hash pattern background
735pub fn pattern_slash(color: Hsla, width: f32, interval: f32) -> Background {
736    let width_scaled = (width * 255.0) as u32;
737    let interval_scaled = (interval * 255.0) as u32;
738    let height = ((width_scaled * 0xFFFF) + interval_scaled) as f32;
739
740    Background {
741        tag: BackgroundTag::PatternSlash,
742        solid: color,
743        gradient_angle_or_pattern_height: height,
744        ..Default::default()
745    }
746}
747
748/// Creates a solid background color.
749pub fn solid_background(color: impl Into<Hsla>) -> Background {
750    Background {
751        solid: color.into(),
752        ..Default::default()
753    }
754}
755
756/// Creates a LinearGradient background color.
757///
758/// The gradient line's angle of direction. A value of `0.` is equivalent to top; increasing values rotate clockwise from there.
759///
760/// The `angle` is in degrees value in the range 0.0 to 360.0.
761///
762/// <https://developer.mozilla.org/en-US/docs/Web/CSS/gradient/linear-gradient>
763pub fn linear_gradient(
764    angle: f32,
765    from: impl Into<LinearColorStop>,
766    to: impl Into<LinearColorStop>,
767) -> Background {
768    Background {
769        tag: BackgroundTag::LinearGradient,
770        gradient_angle_or_pattern_height: angle,
771        colors: [from.into(), to.into()],
772        ..Default::default()
773    }
774}
775
776/// A color stop in a linear gradient.
777///
778/// <https://developer.mozilla.org/en-US/docs/Web/CSS/gradient/linear-gradient#linear-color-stop>
779#[derive(Debug, Clone, Copy, Default, PartialEq, Serialize, Deserialize, JsonSchema)]
780#[repr(C)]
781pub struct LinearColorStop {
782    /// The color of the color stop.
783    pub color: Hsla,
784    /// The percentage of the gradient, in the range 0.0 to 1.0.
785    pub percentage: f32,
786}
787
788/// Creates a new linear color stop.
789///
790/// The percentage of the gradient, in the range 0.0 to 1.0.
791pub fn linear_color_stop(color: impl Into<Hsla>, percentage: f32) -> LinearColorStop {
792    LinearColorStop {
793        color: color.into(),
794        percentage,
795    }
796}
797
798impl LinearColorStop {
799    /// Returns a new color stop with the same color, but with a modified alpha value.
800    pub fn opacity(&self, factor: f32) -> Self {
801        Self {
802            percentage: self.percentage,
803            color: self.color.opacity(factor),
804        }
805    }
806}
807
808impl Background {
809    /// Use specified color space for color interpolation.
810    ///
811    /// <https://developer.mozilla.org/en-US/docs/Web/CSS/color-interpolation-method>
812    pub fn color_space(mut self, color_space: ColorSpace) -> Self {
813        self.color_space = color_space;
814        self
815    }
816
817    /// Returns a new background color with the same hue, saturation, and lightness, but with a modified alpha value.
818    pub fn opacity(&self, factor: f32) -> Self {
819        let mut background = *self;
820        background.solid = background.solid.opacity(factor);
821        background.colors = [
822            self.colors[0].opacity(factor),
823            self.colors[1].opacity(factor),
824        ];
825        background
826    }
827
828    /// Returns whether the background color is transparent.
829    pub fn is_transparent(&self) -> bool {
830        match self.tag {
831            BackgroundTag::Solid => self.solid.is_transparent(),
832            BackgroundTag::LinearGradient => self.colors.iter().all(|c| c.color.is_transparent()),
833            BackgroundTag::PatternSlash => self.solid.is_transparent(),
834        }
835    }
836}
837
838impl From<Hsla> for Background {
839    fn from(value: Hsla) -> Self {
840        Background {
841            tag: BackgroundTag::Solid,
842            solid: value,
843            ..Default::default()
844        }
845    }
846}
847impl From<Rgba> for Background {
848    fn from(value: Rgba) -> Self {
849        Background {
850            tag: BackgroundTag::Solid,
851            solid: Hsla::from(value),
852            ..Default::default()
853        }
854    }
855}
856
857#[cfg(test)]
858mod tests {
859    use serde_json::json;
860
861    use super::*;
862
863    #[test]
864    fn test_deserialize_three_value_hex_to_rgba() {
865        let actual: Rgba = serde_json::from_value(json!("#f09")).unwrap();
866
867        assert_eq!(actual, rgba(0xff0099ff))
868    }
869
870    #[test]
871    fn test_deserialize_four_value_hex_to_rgba() {
872        let actual: Rgba = serde_json::from_value(json!("#f09f")).unwrap();
873
874        assert_eq!(actual, rgba(0xff0099ff))
875    }
876
877    #[test]
878    fn test_deserialize_six_value_hex_to_rgba() {
879        let actual: Rgba = serde_json::from_value(json!("#ff0099")).unwrap();
880
881        assert_eq!(actual, rgba(0xff0099ff))
882    }
883
884    #[test]
885    fn test_deserialize_eight_value_hex_to_rgba() {
886        let actual: Rgba = serde_json::from_value(json!("#ff0099ff")).unwrap();
887
888        assert_eq!(actual, rgba(0xff0099ff))
889    }
890
891    #[test]
892    fn test_deserialize_eight_value_hex_with_padding_to_rgba() {
893        let actual: Rgba = serde_json::from_value(json!(" #f5f5f5ff   ")).unwrap();
894
895        assert_eq!(actual, rgba(0xf5f5f5ff))
896    }
897
898    #[test]
899    fn test_deserialize_eight_value_hex_with_mixed_case_to_rgba() {
900        let actual: Rgba = serde_json::from_value(json!("#DeAdbEeF")).unwrap();
901
902        assert_eq!(actual, rgba(0xdeadbeef))
903    }
904
905    #[test]
906    fn test_background_solid() {
907        let color = Hsla::from(rgba(0xff0099ff));
908        let mut background = Background::from(color);
909        assert_eq!(background.tag, BackgroundTag::Solid);
910        assert_eq!(background.solid, color);
911
912        assert_eq!(background.opacity(0.5).solid, color.opacity(0.5));
913        assert!(!background.is_transparent());
914        background.solid = hsla(0.0, 0.0, 0.0, 0.0);
915        assert!(background.is_transparent());
916    }
917
918    #[test]
919    fn test_background_linear_gradient() {
920        let from = linear_color_stop(rgba(0xff0099ff), 0.0);
921        let to = linear_color_stop(rgba(0x00ff99ff), 1.0);
922        let background = linear_gradient(90.0, from, to);
923        assert_eq!(background.tag, BackgroundTag::LinearGradient);
924        assert_eq!(background.colors[0], from);
925        assert_eq!(background.colors[1], to);
926
927        assert_eq!(background.opacity(0.5).colors[0], from.opacity(0.5));
928        assert_eq!(background.opacity(0.5).colors[1], to.opacity(0.5));
929        assert!(!background.is_transparent());
930        assert!(background.opacity(0.0).is_transparent());
931    }
932}