bevy_color: Added Xyza Colour Space (#12079)

# Objective

Add XYZ colour space. This will be most useful as a conversion step when
working with other (more common) colour spaces. See
[Wikipedia](https://en.wikipedia.org/wiki/CIE_1931_color_space) for
details on this space.

## Solution

- Added `Xyza` to `Color` and as its own type.

---

## Changelog

- Added `Xyza` type.
- Added `Color::Xyza` variant.

## Migration Guide

- `Color` enum now has an additional member, `Xyza`. Convert it to any
other type to handle this case in match statements.

crates/bevy_color/crates/gen_tests/src/main.rs

@@ -1,4 +1,4 @@
-use palette::{Hsl, IntoColor, Lch, LinSrgb, Oklab, Srgb};
+use palette::{Hsl, IntoColor, Lch, LinSrgb, Oklab, Srgb, Xyz};
 
 const TEST_COLORS: &[(f32, f32, f32, &str)] = &[
     (0., 0., 0., "black"),
@@ -25,7 +25,7 @@ fn main() {
     println!(
         "// Generated by gen_tests. Do not edit.
 #[cfg(test)]
-use crate::{{Hsla, Srgba, LinearRgba, Oklaba, Lcha}};
+use crate::{{Hsla, Srgba, LinearRgba, Oklaba, Lcha, Xyza}};
 
 #[cfg(test)]
 pub struct TestColor {{
@@ -35,6 +35,7 @@ pub struct TestColor {{
     pub hsl: Hsla,
     pub lch: Lcha,
     pub oklab: Oklaba,
+    pub xyz: Xyza,
 }}
 "
     );
@@ -48,6 +49,7 @@ pub struct TestColor {{
         let hsl: Hsl = srgb.into_color();
         let lch: Lch = srgb.into_color();
         let oklab: Oklab = srgb.into_color();
+        let xyz: Xyz = srgb.into_color();
         println!("    // {name}");
         println!(
             "    TestColor {{
@@ -57,6 +59,7 @@ pub struct TestColor {{
         hsl: Hsla::new({}, {}, {}, 1.0),
         lch: Lcha::new({}, {}, {}, 1.0),
         oklab: Oklaba::new({}, {}, {}, 1.0),
+        xyz: Xyza::new({}, {}, {}, 1.0),
     }},",
             VariablePrecision(srgb.red),
             VariablePrecision(srgb.green),
@@ -73,6 +76,9 @@ pub struct TestColor {{
             VariablePrecision(oklab.l),
             VariablePrecision(oklab.a),
             VariablePrecision(oklab.b),
+            VariablePrecision(xyz.x),
+            VariablePrecision(xyz.y),
+            VariablePrecision(xyz.z),
         );
     }
     println!("];");

crates/bevy_color/src/color.rs

@@ -1,4 +1,4 @@
-use crate::{Alpha, Hsla, Lcha, LinearRgba, Oklaba, Srgba, StandardColor};
+use crate::{Alpha, Hsla, Lcha, LinearRgba, Oklaba, Srgba, StandardColor, Xyza};
 use bevy_reflect::{Reflect, ReflectDeserialize, ReflectSerialize};
 use bevy_render::color::Color as LegacyColor;
 use serde::{Deserialize, Serialize};
@@ -20,6 +20,8 @@ pub enum Color {
     Lcha(Lcha),
     /// A color in the Oklaba color space with alpha.
     Oklaba(Oklaba),
+    /// A color in the XYZ color space with alpha.
+    Xyza(Xyza),
 }
 
 impl StandardColor for Color {}
@@ -33,6 +35,7 @@ impl Color {
             Color::Hsla(hsla) => (*hsla).into(),
             Color::Lcha(lcha) => (*lcha).into(),
             Color::Oklaba(oklab) => (*oklab).into(),
+            Color::Xyza(xyza) => (*xyza).into(),
         }
     }
 }
@@ -53,6 +56,7 @@ impl Alpha for Color {
             Color::Hsla(x) => *x = x.with_alpha(alpha),
             Color::Lcha(x) => *x = x.with_alpha(alpha),
             Color::Oklaba(x) => *x = x.with_alpha(alpha),
+            Color::Xyza(x) => *x = x.with_alpha(alpha),
         }
 
         new
@@ -65,6 +69,7 @@ impl Alpha for Color {
             Color::Hsla(x) => x.alpha(),
             Color::Lcha(x) => x.alpha(),
             Color::Oklaba(x) => x.alpha(),
+            Color::Xyza(x) => x.alpha(),
         }
     }
 }
@@ -99,6 +104,12 @@ impl From<Lcha> for Color {
     }
 }
 
+impl From<Xyza> for Color {
+    fn from(value: Xyza) -> Self {
+        Self::Xyza(value)
+    }
+}
+
 impl From<Color> for Srgba {
     fn from(value: Color) -> Self {
         match value {
@@ -107,6 +118,7 @@ impl From<Color> for Srgba {
             Color::Hsla(hsla) => hsla.into(),
             Color::Lcha(lcha) => lcha.into(),
             Color::Oklaba(oklab) => oklab.into(),
+            Color::Xyza(xyza) => xyza.into(),
         }
     }
 }
@@ -119,6 +131,7 @@ impl From<Color> for LinearRgba {
             Color::Hsla(hsla) => hsla.into(),
             Color::Lcha(lcha) => lcha.into(),
             Color::Oklaba(oklab) => oklab.into(),
+            Color::Xyza(xyza) => xyza.into(),
         }
     }
 }
@@ -131,6 +144,7 @@ impl From<Color> for Hsla {
             Color::Hsla(hsla) => hsla,
             Color::Lcha(lcha) => LinearRgba::from(lcha).into(),
             Color::Oklaba(oklab) => LinearRgba::from(oklab).into(),
+            Color::Xyza(xyza) => LinearRgba::from(xyza).into(),
         }
     }
 }
@@ -143,6 +157,7 @@ impl From<Color> for Lcha {
             Color::Hsla(hsla) => Srgba::from(hsla).into(),
             Color::Lcha(lcha) => lcha,
             Color::Oklaba(oklab) => LinearRgba::from(oklab).into(),
+            Color::Xyza(xyza) => LinearRgba::from(xyza).into(),
         }
     }
 }
@@ -155,6 +170,20 @@ impl From<Color> for Oklaba {
             Color::Hsla(hsla) => Srgba::from(hsla).into(),
             Color::Lcha(lcha) => LinearRgba::from(lcha).into(),
             Color::Oklaba(oklab) => oklab,
+            Color::Xyza(xyza) => LinearRgba::from(xyza).into(),
+        }
+    }
+}
+
+impl From<Color> for Xyza {
+    fn from(value: Color) -> Self {
+        match value {
+            Color::Srgba(x) => x.into(),
+            Color::LinearRgba(x) => x.into(),
+            Color::Hsla(x) => x.into(),
+            Color::Lcha(x) => x.into(),
+            Color::Oklaba(x) => x.into(),
+            Color::Xyza(xyza) => xyza,
         }
     }
 }
@@ -178,6 +207,7 @@ impl From<Color> for LegacyColor {
             Color::Hsla(x) => x.into(),
             Color::Lcha(x) => x.into(),
             Color::Oklaba(x) => x.into(),
+            Color::Xyza(x) => x.into(),
         }
     }
 }

crates/bevy_color/src/lib.rs

@@ -7,6 +7,7 @@
 //! - [`Hsla`] (hue, saturation, lightness, alpha)
 //! - [`Lcha`] (lightness, chroma, hue, alpha)
 //! - [`Oklaba`] (lightness, a-axis, b-axis, alpha)
+//! - [`Xyza`] (x-axis, y-axis, z-axis, alpha)
 //!
 //! Each of these color spaces is represented as a distinct Rust type.
 //!
@@ -35,6 +36,10 @@
 //! for tasks such as color correction and image analysis, where it is important to be able
 //! to do things like change color saturation without causing hue shifts.
 //!
+//! XYZ is a foundational space commonly used in the definition of other more modern color
+//! spaces. The space is more formally known as CIE 1931, where the `x` and `z` axes represent
+//! a form of chromaticity, while `y` defines an illuminance level.
+//!
 //! See also the [Wikipedia article on color spaces](https://en.wikipedia.org/wiki/Color_space).
 //!
 //! # Conversions
@@ -78,6 +83,7 @@ mod srgba;
 mod test_colors;
 #[cfg(test)]
 mod testing;
+mod xyza;
 
 pub use color::*;
 pub use color_ops::*;
@@ -87,6 +93,7 @@ pub use lcha::*;
 pub use linear_rgba::*;
 pub use oklaba::*;
 pub use srgba::*;
+pub use xyza::*;
 
 use bevy_render::color::Color as LegacyColor;
 
@@ -106,6 +113,7 @@ where
     Self: From<Hsla> + Into<Hsla>,
     Self: From<Lcha> + Into<Lcha>,
     Self: From<Oklaba> + Into<Oklaba>,
+    Self: From<Xyza> + Into<Xyza>,
     Self: Alpha,
 {
 }

crates/bevy_color/src/test_colors.rs

@@ -1,6 +1,6 @@
 // Generated by gen_tests. Do not edit.
 #[cfg(test)]
-use crate::{Hsla, Lcha, LinearRgba, Oklaba, Srgba};
+use crate::{Hsla, Lcha, LinearRgba, Oklaba, Srgba, Xyza};
 
 #[cfg(test)]
 pub struct TestColor {
@@ -10,6 +10,7 @@ pub struct TestColor {
     pub hsl: Hsla,
     pub lch: Lcha,
     pub oklab: Oklaba,
+    pub xyz: Xyza,
 }
 
 // Table of equivalent colors in various color spaces
@@ -23,6 +24,7 @@ pub const TEST_COLORS: &[TestColor] = &[
         hsl: Hsla::new(0.0, 0.0, 0.0, 1.0),
         lch: Lcha::new(0.0, 0.0, 0.0000136603785, 1.0),
         oklab: Oklaba::new(0.0, 0.0, 0.0, 1.0),
+        xyz: Xyza::new(0.0, 0.0, 0.0, 1.0),
     },
     // white
     TestColor {
@@ -32,6 +34,7 @@ pub const TEST_COLORS: &[TestColor] = &[
         hsl: Hsla::new(0.0, 0.0, 1.0, 1.0),
         lch: Lcha::new(1.0, 0.0, 0.0000136603785, 1.0),
         oklab: Oklaba::new(1.0, 0.0, 0.000000059604645, 1.0),
+        xyz: Xyza::new(0.95047, 1.0, 1.08883, 1.0),
     },
     // red
     TestColor {
@@ -41,6 +44,7 @@ pub const TEST_COLORS: &[TestColor] = &[
         hsl: Hsla::new(0.0, 1.0, 0.5, 1.0),
         lch: Lcha::new(0.53240794, 1.0455177, 39.99901, 1.0),
         oklab: Oklaba::new(0.6279554, 0.22486295, 0.1258463, 1.0),
+        xyz: Xyza::new(0.4124564, 0.2126729, 0.0193339, 1.0),
     },
     // green
     TestColor {
@@ -50,6 +54,7 @@ pub const TEST_COLORS: &[TestColor] = &[
         hsl: Hsla::new(120.0, 1.0, 0.5, 1.0),
         lch: Lcha::new(0.87734723, 1.1977587, 136.01595, 1.0),
         oklab: Oklaba::new(0.8664396, -0.2338874, 0.1794985, 1.0),
+        xyz: Xyza::new(0.3575761, 0.7151522, 0.119192, 1.0),
     },
     // blue
     TestColor {
@@ -59,6 +64,7 @@ pub const TEST_COLORS: &[TestColor] = &[
         hsl: Hsla::new(240.0, 1.0, 0.5, 1.0),
         lch: Lcha::new(0.32297012, 1.3380761, 306.28494, 1.0),
         oklab: Oklaba::new(0.4520137, -0.032456964, -0.31152815, 1.0),
+        xyz: Xyza::new(0.1804375, 0.072175, 0.9503041, 1.0),
     },
     // yellow
     TestColor {
@@ -68,6 +74,7 @@ pub const TEST_COLORS: &[TestColor] = &[
         hsl: Hsla::new(60.0, 1.0, 0.5, 1.0),
         lch: Lcha::new(0.9713927, 0.96905375, 102.85126, 1.0),
         oklab: Oklaba::new(0.9679827, -0.07136908, 0.19856972, 1.0),
+        xyz: Xyza::new(0.7700325, 0.9278251, 0.1385259, 1.0),
     },
     // magenta
     TestColor {
@@ -77,6 +84,7 @@ pub const TEST_COLORS: &[TestColor] = &[
         hsl: Hsla::new(300.0, 1.0, 0.5, 1.0),
         lch: Lcha::new(0.6032421, 1.1554068, 328.23495, 1.0),
         oklab: Oklaba::new(0.7016738, 0.27456632, -0.16915613, 1.0),
+        xyz: Xyza::new(0.5928939, 0.28484792, 0.969638, 1.0),
     },
     // cyan
     TestColor {
@@ -86,6 +94,7 @@ pub const TEST_COLORS: &[TestColor] = &[
         hsl: Hsla::new(180.0, 1.0, 0.5, 1.0),
         lch: Lcha::new(0.9111322, 0.50120866, 196.37614, 1.0),
         oklab: Oklaba::new(0.90539926, -0.1494439, -0.039398134, 1.0),
+        xyz: Xyza::new(0.5380136, 0.78732723, 1.069496, 1.0),
     },
     // gray
     TestColor {
@@ -95,6 +104,7 @@ pub const TEST_COLORS: &[TestColor] = &[
         hsl: Hsla::new(0.0, 0.0, 0.5, 1.0),
         lch: Lcha::new(0.5338897, 0.00000011920929, 90.0, 1.0),
         oklab: Oklaba::new(0.5981807, 0.00000011920929, 0.0, 1.0),
+        xyz: Xyza::new(0.2034397, 0.21404117, 0.23305441, 1.0),
     },
     // olive
     TestColor {
@@ -104,6 +114,7 @@ pub const TEST_COLORS: &[TestColor] = &[
         hsl: Hsla::new(60.0, 1.0, 0.25, 1.0),
         lch: Lcha::new(0.51677734, 0.57966936, 102.851265, 1.0),
         oklab: Oklaba::new(0.57902855, -0.042691574, 0.11878061, 1.0),
+        xyz: Xyza::new(0.16481864, 0.19859275, 0.029650241, 1.0),
     },
     // purple
     TestColor {
@@ -113,6 +124,7 @@ pub const TEST_COLORS: &[TestColor] = &[
         hsl: Hsla::new(300.0, 1.0, 0.25, 1.0),
         lch: Lcha::new(0.29655674, 0.69114214, 328.23495, 1.0),
         oklab: Oklaba::new(0.41972777, 0.1642403, -0.10118592, 1.0),
+        xyz: Xyza::new(0.12690368, 0.060969174, 0.20754242, 1.0),
     },
     // teal
     TestColor {
@@ -122,6 +134,7 @@ pub const TEST_COLORS: &[TestColor] = &[
         hsl: Hsla::new(180.0, 1.0, 0.25, 1.0),
         lch: Lcha::new(0.48073065, 0.29981336, 196.37614, 1.0),
         oklab: Oklaba::new(0.54159236, -0.08939436, -0.02356726, 1.0),
+        xyz: Xyza::new(0.11515705, 0.16852042, 0.22891617, 1.0),
     },
     // maroon
     TestColor {
@@ -131,6 +144,7 @@ pub const TEST_COLORS: &[TestColor] = &[
         hsl: Hsla::new(0.0, 1.0, 0.25, 1.0),
         lch: Lcha::new(0.2541851, 0.61091745, 38.350803, 1.0),
         oklab: Oklaba::new(0.3756308, 0.13450874, 0.07527886, 1.0),
+        xyz: Xyza::new(0.08828264, 0.045520753, 0.0041382504, 1.0),
     },
     // lime
     TestColor {
@@ -140,6 +154,7 @@ pub const TEST_COLORS: &[TestColor] = &[
         hsl: Hsla::new(120.0, 1.0, 0.25, 1.0),
         lch: Lcha::new(0.46052113, 0.71647626, 136.01596, 1.0),
         oklab: Oklaba::new(0.5182875, -0.13990697, 0.10737252, 1.0),
+        xyz: Xyza::new(0.076536, 0.153072, 0.025511991, 1.0),
     },
     // navy
     TestColor {
@@ -149,6 +164,7 @@ pub const TEST_COLORS: &[TestColor] = &[
         hsl: Hsla::new(240.0, 1.0, 0.25, 1.0),
         lch: Lcha::new(0.12890343, 0.8004114, 306.28494, 1.0),
         oklab: Oklaba::new(0.27038592, -0.01941514, -0.18635012, 1.0),
+        xyz: Xyza::new(0.03862105, 0.01544842, 0.20340417, 1.0),
     },
     // orange
     TestColor {
@@ -158,6 +174,7 @@ pub const TEST_COLORS: &[TestColor] = &[
         hsl: Hsla::new(60.0, 1.0, 0.25, 1.0),
         lch: Lcha::new(0.51677734, 0.57966936, 102.851265, 1.0),
         oklab: Oklaba::new(0.57902855, -0.042691574, 0.11878061, 1.0),
+        xyz: Xyza::new(0.16481864, 0.19859275, 0.029650241, 1.0),
     },
     // fuchsia
     TestColor {
@@ -167,6 +184,7 @@ pub const TEST_COLORS: &[TestColor] = &[
         hsl: Hsla::new(300.0, 1.0, 0.25, 1.0),
         lch: Lcha::new(0.29655674, 0.69114214, 328.23495, 1.0),
         oklab: Oklaba::new(0.41972777, 0.1642403, -0.10118592, 1.0),
+        xyz: Xyza::new(0.12690368, 0.060969174, 0.20754242, 1.0),
     },
     // aqua
     TestColor {
@@ -176,5 +194,6 @@ pub const TEST_COLORS: &[TestColor] = &[
         hsl: Hsla::new(180.0, 1.0, 0.25, 1.0),
         lch: Lcha::new(0.48073065, 0.29981336, 196.37614, 1.0),
         oklab: Oklaba::new(0.54159236, -0.08939436, -0.02356726, 1.0),
+        xyz: Xyza::new(0.11515705, 0.16852042, 0.22891617, 1.0),
     },
 ];

crates/bevy_color/src/xyza.rs

@@ -0,0 +1,245 @@
+use crate::{Alpha, Hsla, Lcha, LinearRgba, Luminance, Mix, Oklaba, Srgba, StandardColor};
+use bevy_reflect::{Reflect, ReflectDeserialize, ReflectSerialize};
+use bevy_render::color::Color;
+use serde::{Deserialize, Serialize};
+
+/// [CIE 1931](https://en.wikipedia.org/wiki/CIE_1931_color_space) color space, also known as XYZ, with an alpha channel.
+#[derive(Debug, Clone, Copy, PartialEq, Serialize, Deserialize, Reflect)]
+#[reflect(PartialEq, Serialize, Deserialize)]
+pub struct Xyza {
+    /// The x-axis. [0.0, 1.0]
+    pub x: f32,
+    /// The y-axis, intended to represent luminance. [0.0, 1.0]
+    pub y: f32,
+    /// The z-axis. [0.0, 1.0]
+    pub z: f32,
+    /// The alpha channel. [0.0, 1.0]
+    pub alpha: f32,
+}
+
+impl StandardColor for Xyza {}
+
+impl Xyza {
+    /// Construct a new [`Xyza`] color from components.
+    ///
+    /// # Arguments
+    ///
+    /// * `x` - x-axis. [0.0, 1.0]
+    /// * `y` - y-axis. [0.0, 1.0]
+    /// * `z` - z-axis. [0.0, 1.0]
+    /// * `alpha` - Alpha channel. [0.0, 1.0]
+    pub const fn new(x: f32, y: f32, z: f32, alpha: f32) -> Self {
+        Self { x, y, z, alpha }
+    }
+
+    /// Construct a new [`Xyza`] color from (x, y, z) components, with the default alpha (1.0).
+    ///
+    /// # Arguments
+    ///
+    /// * `x` - x-axis. [0.0, 1.0]
+    /// * `y` - y-axis. [0.0, 1.0]
+    /// * `z` - z-axis. [0.0, 1.0]
+    pub const fn rgb(x: f32, y: f32, z: f32) -> Self {
+        Self {
+            x,
+            y,
+            z,
+            alpha: 1.0,
+        }
+    }
+}
+
+impl Default for Xyza {
+    fn default() -> Self {
+        Self::new(0., 0., 0., 1.)
+    }
+}
+
+impl Alpha for Xyza {
+    #[inline]
+    fn with_alpha(&self, alpha: f32) -> Self {
+        Self { alpha, ..*self }
+    }
+
+    #[inline]
+    fn alpha(&self) -> f32 {
+        self.alpha
+    }
+}
+
+impl Luminance for Xyza {
+    #[inline]
+    fn with_luminance(&self, lightness: f32) -> Self {
+        Self {
+            y: lightness,
+            ..*self
+        }
+    }
+
+    fn luminance(&self) -> f32 {
+        self.y
+    }
+
+    fn darker(&self, amount: f32) -> Self {
+        Self {
+            y: (self.y - amount).clamp(0., 1.),
+            ..*self
+        }
+    }
+
+    fn lighter(&self, amount: f32) -> Self {
+        Self {
+            y: (self.y + amount).min(1.),
+            ..*self
+        }
+    }
+}
+
+impl Mix for Xyza {
+    #[inline]
+    fn mix(&self, other: &Self, factor: f32) -> Self {
+        let n_factor = 1.0 - factor;
+        Self {
+            x: self.x * n_factor + other.x * factor,
+            y: self.y * n_factor + other.y * factor,
+            z: self.z * n_factor + other.z * factor,
+            alpha: self.alpha * n_factor + other.alpha * factor,
+        }
+    }
+}
+
+impl From<LinearRgba> for Xyza {
+    fn from(
+        LinearRgba {
+            red,
+            green,
+            blue,
+            alpha,
+        }: LinearRgba,
+    ) -> Self {
+        // Linear sRGB to XYZ
+        // http://www.brucelindbloom.com/index.html?Eqn_XYZ_to_RGB.html
+        // http://www.brucelindbloom.com/index.html?Eqn_RGB_XYZ_Matrix.html (sRGB, RGB to XYZ [M])
+        let r = red;
+        let g = green;
+        let b = blue;
+
+        let x = r * 0.4124564 + g * 0.3575761 + b * 0.1804375;
+        let y = r * 0.2126729 + g * 0.7151522 + b * 0.072175;
+        let z = r * 0.0193339 + g * 0.119192 + b * 0.9503041;
+
+        Xyza::new(x, y, z, alpha)
+    }
+}
+
+impl From<Xyza> for LinearRgba {
+    fn from(Xyza { x, y, z, alpha }: Xyza) -> Self {
+        // XYZ to Linear sRGB
+        // http://www.brucelindbloom.com/index.html?Eqn_XYZ_to_RGB.html
+        // http://www.brucelindbloom.com/index.html?Eqn_RGB_XYZ_Matrix.html (sRGB, XYZ to RGB [M]-1)
+        let r = x * 3.2404542 + y * -1.5371385 + z * -0.4985314;
+        let g = x * -0.969266 + y * 1.8760108 + z * 0.041556;
+        let b = x * 0.0556434 + y * -0.2040259 + z * 1.0572252;
+
+        LinearRgba::new(r, g, b, alpha)
+    }
+}
+
+impl From<Srgba> for Xyza {
+    fn from(value: Srgba) -> Self {
+        LinearRgba::from(value).into()
+    }
+}
+
+impl From<Xyza> for Srgba {
+    fn from(value: Xyza) -> Self {
+        LinearRgba::from(value).into()
+    }
+}
+
+impl From<Hsla> for Xyza {
+    fn from(value: Hsla) -> Self {
+        LinearRgba::from(value).into()
+    }
+}
+
+impl From<Xyza> for Hsla {
+    fn from(value: Xyza) -> Self {
+        LinearRgba::from(value).into()
+    }
+}
+
+impl From<Lcha> for Xyza {
+    fn from(value: Lcha) -> Self {
+        LinearRgba::from(value).into()
+    }
+}
+
+impl From<Xyza> for Lcha {
+    fn from(value: Xyza) -> Self {
+        LinearRgba::from(value).into()
+    }
+}
+
+impl From<Oklaba> for Xyza {
+    fn from(value: Oklaba) -> Self {
+        LinearRgba::from(value).into()
+    }
+}
+
+impl From<Xyza> for Oklaba {
+    fn from(value: Xyza) -> Self {
+        LinearRgba::from(value).into()
+    }
+}
+
+impl From<Color> for Xyza {
+    fn from(value: Color) -> Self {
+        LinearRgba::from(value).into()
+    }
+}
+
+impl From<Xyza> for Color {
+    fn from(value: Xyza) -> Self {
+        LinearRgba::from(value).into()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::{
+        color_difference::EuclideanDistance, test_colors::TEST_COLORS, testing::assert_approx_eq,
+        Srgba,
+    };
+
+    #[test]
+    fn test_to_from_srgba() {
+        let xyza = Xyza::new(0.5, 0.5, 0.5, 1.0);
+        let srgba: Srgba = xyza.into();
+        let xyza2: Xyza = srgba.into();
+        assert_approx_eq!(xyza.x, xyza2.x, 0.001);
+        assert_approx_eq!(xyza.y, xyza2.y, 0.001);
+        assert_approx_eq!(xyza.z, xyza2.z, 0.001);
+        assert_approx_eq!(xyza.alpha, xyza2.alpha, 0.001);
+    }
+
+    #[test]
+    fn test_to_from_srgba_2() {
+        for color in TEST_COLORS.iter() {
+            let rgb2: Srgba = (color.xyz).into();
+            let xyz2: Xyza = (color.rgb).into();
+            assert!(
+                color.rgb.distance(&rgb2) < 0.00001,
+                "{}: {:?} != {:?}",
+                color.name,
+                color.rgb,
+                rgb2
+            );
+            assert_approx_eq!(color.xyz.x, xyz2.x, 0.001);
+            assert_approx_eq!(color.xyz.y, xyz2.y, 0.001);
+            assert_approx_eq!(color.xyz.z, xyz2.z, 0.001);
+            assert_approx_eq!(color.xyz.alpha, xyz2.alpha, 0.001);
+        }
+    }
+}