colr 0.1.0

//! Standard RGB color spaces, channel layouts, and their transforms.
//!
//! Layout is a parameter of the space: `RgbSpace<P, TF, L>` where `L` defaults
//! to `Rgba`. Chromatic adaptation uses Bradford per ICC, ACES, and CSS Color 4.
//!
//! # Space catalogue
//!
//! | Alias          | Primaries | Transfer fn | White |
//! |----------------|-----------|-------------|-------|
//! | Srgb           | sRGB/709  | sRGB        | D65   |
//! | LinearSrgb     | sRGB/709  | Linear      | D65   |
//! | Rec709         | sRGB/709  | Rec. 709    | D65   |
//! | DisplayP3      | P3        | sRGB        | D65   |
//! | LinearP3       | P3        | Linear      | D65   |
//! | Hdr10          | Rec. 2020 | PQ          | D65   |
//! | Hlg            | Rec. 2020 | HLG         | D65   |
//! | LinearRec2020  | Rec. 2020 | Linear      | D65   |
//! | AcesCg         | AP1       | Linear      | ACES  |
//! | Aces2065       | AP0       | Linear      | ACES  |
//! | AcesCc         | AP1       | ACEScc      | ACES  |
//! | AcesCct        | AP1       | ACEScct     | ACES  |
//! | ProPhoto       | ProPhoto  | ProPhoto    | D50   |
//! | LinearProPhoto | ProPhoto  | Linear      | D50   |
//! | DciP3          | DCI-P3    | gamma 2.6   | DCI   |
//! | P3D65Gamma26   | P3        | gamma 2.6   | D65   |

use core::marker::PhantomData;

use crate::adaptation::Bradford;
use crate::illuminant::Illuminant;
use crate::math::{DefaultMath, Mat3};
use crate::primaries::{
    AcesAp0Primaries, AcesAp1Primaries, DciP3Primaries, P3Primaries, Primaries, PrimariesToXyz, ProPhotoPrimaries,
    Rec2020Primaries, SrgbPrimaries,
};
use crate::transfer::{
    AcesCcTf, AcesCctTf, DciP3Tf, HlgTf, IsDisplayReferred, IsLinearEncoding, IsSceneReferred, LinearTf, PqTf,
    ProPhotoTf, Rec709Tf, SrgbTf, TransferFunction,
};
use crate::xyz::Xyz;
use crate::{
    Asserts, Color, ColorSpace, DisplayReferred, LinearLight, OutOfGamut, SceneReferred, Transform, TryTransform,
};

/// Maps all N channels to their storage indices.
///
/// INDICES contains the storage position of each logical channel in order.
/// For RGB layouts the first three are R, G, B. ALPHA points to which
/// position within INDICES holds alpha, if any.
pub trait ChannelMap<const N: usize>: 'static {
    /// Storage positions of all N channels in logical order.
    const INDICES: [usize; N];
    /// Which position within INDICES holds alpha, if any.
    const ALPHA: Option<usize>;
}

macro_rules! define_layout {
    ($name:ident, [$r:expr, $g:expr, $b:expr, $a:expr]) => {
        #[doc = concat!("Four-channel layout. R=`", stringify!($r), "` G=`", stringify!($g), "` B=`", stringify!($b), "` A=`", stringify!($a), "`.")]
        #[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
        pub struct $name;
        impl Asserts<[f32; 4]> for $name {}
        #[cfg(feature = "glam")]
        impl Asserts<glam::Vec4> for $name {}
        impl ChannelMap<4> for $name {
            const INDICES: [usize; 4] = [$r, $g, $b, $a];
            const ALPHA: Option<usize> = Some(3);
        }
    };
    ($name:ident, [$r:expr, $g:expr, $b:expr]) => {
        #[doc = concat!("Three-channel layout. R=`", stringify!($r), "` G=`", stringify!($g), "` B=`", stringify!($b), "`. No alpha.")]
        #[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
        pub struct $name;
        impl Asserts<[f32; 3]> for $name {}
        #[cfg(feature = "glam")]
        impl Asserts<glam::Vec3> for $name {}
        #[cfg(feature = "glam")]
        impl Asserts<glam::Vec3A> for $name {}
        impl ChannelMap<3> for $name {
            const INDICES: [usize; 3] = [$r, $g, $b];
            const ALPHA: Option<usize> = None;
        }
    };
    ($name:ident, [$a:expr, $b:expr]) => {
        /// Two-channel layout.
        #[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
        pub struct $name;
        impl Asserts<[f32; 2]> for $name {}
        #[cfg(feature = "glam")]
        impl Asserts<glam::Vec2> for $name {}
        impl ChannelMap<2> for $name {
            const INDICES: [usize; 2] = [$a, $b];
            const ALPHA: Option<usize> = None;
        }
    };
    ($name:ident, [$a:expr], alpha) => {
        /// Single alpha channel layout.
        #[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
        pub struct $name;
        impl Asserts<[f32; 1]> for $name {}
        impl Asserts<f32> for $name {}
        impl ChannelMap<1> for $name {
            const INDICES: [usize; 1] = [$a];
            const ALPHA: Option<usize> = Some(0);
        }
    };
    ($name:ident, [$a:expr]) => {
        /// Single-channel layout.
        #[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
        pub struct $name;
        impl Asserts<[f32; 1]> for $name {}
        impl Asserts<f32> for $name {}
        impl ChannelMap<1> for $name {
            const INDICES: [usize; 1] = [$a];
            const ALPHA: Option<usize> = None;
        }
    };
}

define_layout!(Rgba, [0, 1, 2, 3]);
define_layout!(Bgra, [2, 1, 0, 3]);
define_layout!(Argb, [1, 2, 3, 0]);
define_layout!(Abgr, [3, 2, 1, 0]);
define_layout!(Rgb, [0, 1, 2]);
define_layout!(Bgr, [2, 1, 0]);
define_layout!(Rg, [0, 1]);
define_layout!(Ra, [0, 1]);
define_layout!(R, [0]);
define_layout!(G, [0]);
define_layout!(B, [0]);
define_layout!(A, [0], alpha);

/// A color space formed by composing primaries P, transfer function TF,
/// and channel layout L. Layout defaults to Rgba.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
pub struct RgbSpace<P: Primaries, TF: TransferFunction, L = Rgba>(PhantomData<(P, TF, L)>);

/// Marker for color spaces using the RGB channel model.
pub trait RgbColorSpace: ColorSpace {}

impl<P, TF, L> RgbColorSpace for RgbSpace<P, TF, L>
where
    P: Primaries,
    TF: TransferFunction,
    L: 'static,
{
}

impl<P, TF, L> ColorSpace for RgbSpace<P, TF, L>
where
    P: Primaries,
    TF: TransferFunction,
    L: 'static,
{
    const CHANNELS: usize = 3;
    const LUMINANCE_WEIGHTS: Option<[f32; 3]> = Some(P::TO_XYZ_NATIVE.luminance_weights());
}

impl<P, TF, L, S> Asserts<S> for RgbSpace<P, TF, L>
where
    P: Primaries,
    TF: TransferFunction,
    L: Asserts<S> + 'static,
    S: 'static,
{
}

impl<P, TF, L> LinearLight for RgbSpace<P, TF, L>
where
    P: Primaries,
    TF: TransferFunction + IsLinearEncoding,
    L: 'static,
{
}

impl<P, TF, L> SceneReferred for RgbSpace<P, TF, L>
where
    P: Primaries,
    TF: TransferFunction + IsSceneReferred,
    L: 'static,
{
}

impl<P, TF, L> DisplayReferred for RgbSpace<P, TF, L>
where
    P: Primaries,
    TF: TransferFunction + IsDisplayReferred,
    L: 'static,
{
}

// Compile-time matrix for direct primaries-to-primaries transform.
const fn direct_matrix<P1: Primaries, P2: Primaries>() -> Mat3 {
    use crate::adaptation::adapt;
    let a = adapt::<Bradford>(P1::Native::WHITE_POINT_XYZ, P2::Native::WHITE_POINT_XYZ);
    let adapted = Mat3::mul(&a, &P1::TO_XYZ_NATIVE);
    Mat3::mul(&P2::FROM_XYZ_NATIVE, &adapted)
}

// Layout reorder, four channel. Infallible.
impl<P, TF, L1, L2> Transform<Color<[f32; 4], RgbSpace<P, TF, L1>>> for Color<[f32; 4], RgbSpace<P, TF, L2>>
where
    P: Primaries,
    TF: TransferFunction,
    L1: Asserts<[f32; 4]> + ChannelMap<4> + 'static,
    L2: Asserts<[f32; 4]> + ChannelMap<4> + 'static,
{
    fn transform_from(src: Color<[f32; 4], RgbSpace<P, TF, L1>>, _: &()) -> Self {
        let s = src.inner();
        let [r1, g1, b1, a1] = L1::INDICES;
        let [r2, g2, b2, a2] = L2::INDICES;
        let mut out = [0.0f32; 4];
        out[r2] = s[r1];
        out[g2] = s[g1];
        out[b2] = s[b1];
        out[a2] = s[a1];
        Color::new_unchecked(out)
    }
}

// Layout reorder, three channel. Infallible.
impl<P, TF, L1, L2> Transform<Color<[f32; 3], RgbSpace<P, TF, L1>>> for Color<[f32; 3], RgbSpace<P, TF, L2>>
where
    P: Primaries,
    TF: TransferFunction,
    L1: Asserts<[f32; 3]> + ChannelMap<3> + 'static,
    L2: Asserts<[f32; 3]> + ChannelMap<3> + 'static,
{
    fn transform_from(src: Color<[f32; 3], RgbSpace<P, TF, L1>>, _: &()) -> Self {
        let s = src.inner();
        let [r1, g1, b1] = L1::INDICES;
        let [r2, g2, b2] = L2::INDICES;
        let mut out = [0.0f32; 3];
        out[r2] = s[r1];
        out[g2] = s[g1];
        out[b2] = s[b1];
        Color::new_unchecked(out)
    }
}

// RGB to XYZ, infallible, [f32; 4].
impl<P, TF, W, L> Transform<Color<[f32; 4], RgbSpace<P, TF, L>>> for Color<[f32; 4], Xyz<W>>
where
    P: Primaries + PrimariesToXyz<W, Bradford>,
    TF: TransferFunction,
    W: Illuminant,
    L: Asserts<[f32; 4]> + ChannelMap<4> + 'static,
    Xyz<W>: Asserts<[f32; 4]>,
{
    fn transform_from(src: Color<[f32; 4], RgbSpace<P, TF, L>>, _: &()) -> Self {
        let s = src.inner();
        let [ri, gi, bi, ai] = L::INDICES;
        let rgb = TF::decode::<DefaultMath>([s[ri], s[gi], s[bi]]);
        let xyz = <P as PrimariesToXyz<W, Bradford>>::TO_XYZ.apply(rgb);
        Color::new_unchecked([xyz[0], xyz[1], xyz[2], s[ai]])
    }
}

// XYZ to RGB, fallible, [f32; 4].
impl<P, TF, W, L> TryTransform<Color<[f32; 4], Xyz<W>>> for Color<[f32; 4], RgbSpace<P, TF, L>>
where
    P: Primaries + PrimariesToXyz<W, Bradford>,
    TF: TransferFunction,
    W: Illuminant,
    L: Asserts<[f32; 4]> + ChannelMap<4> + 'static,
    Xyz<W>: Asserts<[f32; 4]>,
{
    fn try_transform_from(src: Color<[f32; 4], Xyz<W>>, _: &()) -> Result<Self, OutOfGamut<Self>> {
        let x = src.inner();
        let rgb = <P as PrimariesToXyz<W, Bradford>>::FROM_XYZ.apply([x[0], x[1], x[2]]);
        let enc = TF::encode::<DefaultMath>(rgb);
        let [ri, gi, bi, ai] = L::INDICES;
        let mut s = [0.0f32; 4];
        s[ri] = enc[0];
        s[gi] = enc[1];
        s[bi] = enc[2];
        s[ai] = x[3];
        let min = TF::ENCODED_MIN;
        let max = TF::ENCODED_MAX;
        let clipped = enc[0] < min[0]
            || enc[0] > max[0]
            || enc[1] < min[1]
            || enc[1] > max[1]
            || enc[2] < min[2]
            || enc[2] > max[2]
            || enc[0].is_nan()
            || enc[1].is_nan()
            || enc[2].is_nan();
        if clipped {
            let c = |v: f32, lo: f32| if v.is_nan() { lo } else { v };
            s[ri] = c(enc[0], min[0]).clamp(min[0], max[0]);
            s[gi] = c(enc[1], min[1]).clamp(min[1], max[1]);
            s[bi] = c(enc[2], min[2]).clamp(min[2], max[2]);
            Err(OutOfGamut {
                clamped: Color::new_unchecked(s),
            })
        } else {
            Ok(Color::new_unchecked(s))
        }
    }
}

// RGB to XYZ, infallible, [f32; 3].
impl<P, TF, W, L> Transform<Color<[f32; 3], RgbSpace<P, TF, L>>> for Color<[f32; 3], Xyz<W>>
where
    P: Primaries + PrimariesToXyz<W, Bradford>,
    TF: TransferFunction,
    W: Illuminant,
    L: Asserts<[f32; 3]> + ChannelMap<3> + 'static,
    Xyz<W>: Asserts<[f32; 3]>,
{
    fn transform_from(src: Color<[f32; 3], RgbSpace<P, TF, L>>, _: &()) -> Self {
        let s = src.inner();
        let [ri, gi, bi] = L::INDICES;
        let rgb = TF::decode::<DefaultMath>([s[ri], s[gi], s[bi]]);
        let xyz = <P as PrimariesToXyz<W, Bradford>>::TO_XYZ.apply(rgb);
        Color::new_unchecked([xyz[0], xyz[1], xyz[2]])
    }
}

// XYZ to RGB, fallible, [f32; 3].
impl<P, TF, W, L> TryTransform<Color<[f32; 3], Xyz<W>>> for Color<[f32; 3], RgbSpace<P, TF, L>>
where
    P: Primaries + PrimariesToXyz<W, Bradford>,
    TF: TransferFunction,
    W: Illuminant,
    L: Asserts<[f32; 3]> + ChannelMap<3> + 'static,
    Xyz<W>: Asserts<[f32; 3]>,
{
    fn try_transform_from(src: Color<[f32; 3], Xyz<W>>, _: &()) -> Result<Self, OutOfGamut<Self>> {
        let x = src.inner();
        let rgb = <P as PrimariesToXyz<W, Bradford>>::FROM_XYZ.apply([x[0], x[1], x[2]]);
        let enc = TF::encode::<DefaultMath>(rgb);
        let [ri, gi, bi] = L::INDICES;
        let mut s = [0.0f32; 3];
        s[ri] = enc[0];
        s[gi] = enc[1];
        s[bi] = enc[2];
        let min = TF::ENCODED_MIN;
        let max = TF::ENCODED_MAX;
        let clipped = enc[0] < min[0]
            || enc[0] > max[0]
            || enc[1] < min[1]
            || enc[1] > max[1]
            || enc[2] < min[2]
            || enc[2] > max[2]
            || enc[0].is_nan()
            || enc[1].is_nan()
            || enc[2].is_nan();
        if clipped {
            let c = |v: f32, lo: f32| if v.is_nan() { lo } else { v };
            s[ri] = c(enc[0], min[0]).clamp(min[0], max[0]);
            s[gi] = c(enc[1], min[1]).clamp(min[1], max[1]);
            s[bi] = c(enc[2], min[2]).clamp(min[2], max[2]);
            Err(OutOfGamut {
                clamped: Color::new_unchecked(s),
            })
        } else {
            Ok(Color::new_unchecked(s))
        }
    }
}

#[cfg(feature = "glam")]
impl<P, TF, W, L> Transform<Color<glam::Vec4, RgbSpace<P, TF, L>>> for Color<glam::Vec4, Xyz<W>>
where
    P: Primaries + PrimariesToXyz<W, Bradford>,
    TF: TransferFunction,
    W: Illuminant,
    L: Asserts<glam::Vec4> + ChannelMap<4> + 'static,
    Xyz<W>: Asserts<glam::Vec4>,
{
    fn transform_from(src: Color<glam::Vec4, RgbSpace<P, TF, L>>, _: &()) -> Self {
        let s = src.inner().to_array();
        let [ri, gi, bi, ai] = L::INDICES;
        let rgb = TF::decode::<DefaultMath>([s[ri], s[gi], s[bi]]);
        let xyz = <P as PrimariesToXyz<W, Bradford>>::TO_XYZ.apply(rgb);
        Color::new_unchecked(glam::Vec4::new(xyz[0], xyz[1], xyz[2], s[ai]))
    }
}

#[cfg(feature = "glam")]
impl<P, TF, W, L> TryTransform<Color<glam::Vec4, Xyz<W>>> for Color<glam::Vec4, RgbSpace<P, TF, L>>
where
    P: Primaries + PrimariesToXyz<W, Bradford>,
    TF: TransferFunction,
    W: Illuminant,
    L: Asserts<glam::Vec4> + ChannelMap<4> + 'static,
    Xyz<W>: Asserts<glam::Vec4>,
{
    fn try_transform_from(src: Color<glam::Vec4, Xyz<W>>, _: &()) -> Result<Self, OutOfGamut<Self>> {
        let x = src.inner().to_array();
        let rgb = <P as PrimariesToXyz<W, Bradford>>::FROM_XYZ.apply([x[0], x[1], x[2]]);
        let enc = TF::encode::<DefaultMath>(rgb);
        let [ri, gi, bi, ai] = L::INDICES;
        let mut s = [0.0f32; 4];
        s[ri] = enc[0];
        s[gi] = enc[1];
        s[bi] = enc[2];
        s[ai] = x[3];
        let min = TF::ENCODED_MIN;
        let max = TF::ENCODED_MAX;
        let clipped = enc[0] < min[0]
            || enc[0] > max[0]
            || enc[1] < min[1]
            || enc[1] > max[1]
            || enc[2] < min[2]
            || enc[2] > max[2]
            || enc[0].is_nan()
            || enc[1].is_nan()
            || enc[2].is_nan();
        if clipped {
            let c = |v: f32, lo: f32| if v.is_nan() { lo } else { v };
            s[ri] = c(enc[0], min[0]).clamp(min[0], max[0]);
            s[gi] = c(enc[1], min[1]).clamp(min[1], max[1]);
            s[bi] = c(enc[2], min[2]).clamp(min[2], max[2]);
            Err(OutOfGamut {
                clamped: Color::new_unchecked(glam::Vec4::from_array(s)),
            })
        } else {
            Ok(Color::new_unchecked(glam::Vec4::from_array(s)))
        }
    }
}

#[cfg(feature = "glam")]
impl<P, TF, W, L> Transform<Color<glam::Vec3A, RgbSpace<P, TF, L>>> for Color<glam::Vec3A, Xyz<W>>
where
    P: Primaries + PrimariesToXyz<W, Bradford>,
    TF: TransferFunction,
    W: Illuminant,
    L: Asserts<glam::Vec3A> + ChannelMap<3> + 'static,
    Xyz<W>: Asserts<glam::Vec3A>,
{
    fn transform_from(src: Color<glam::Vec3A, RgbSpace<P, TF, L>>, _: &()) -> Self {
        let s = src.inner().to_array();
        let [ri, gi, bi] = L::INDICES;
        let rgb = TF::decode::<DefaultMath>([s[ri], s[gi], s[bi]]);
        let xyz = <P as PrimariesToXyz<W, Bradford>>::TO_XYZ.apply(rgb);
        Color::new_unchecked(glam::Vec3A::new(xyz[0], xyz[1], xyz[2]))
    }
}

#[cfg(feature = "glam")]
impl<P, TF, W, L> TryTransform<Color<glam::Vec3A, Xyz<W>>> for Color<glam::Vec3A, RgbSpace<P, TF, L>>
where
    P: Primaries + PrimariesToXyz<W, Bradford>,
    TF: TransferFunction,
    W: Illuminant,
    L: Asserts<glam::Vec3A> + ChannelMap<3> + 'static,
    Xyz<W>: Asserts<glam::Vec3A>,
{
    fn try_transform_from(src: Color<glam::Vec3A, Xyz<W>>, _: &()) -> Result<Self, OutOfGamut<Self>> {
        let x = src.inner().to_array();
        let rgb = <P as PrimariesToXyz<W, Bradford>>::FROM_XYZ.apply([x[0], x[1], x[2]]);
        let enc = TF::encode::<DefaultMath>(rgb);
        let [ri, gi, bi] = L::INDICES;
        let mut s = [0.0f32; 3];
        s[ri] = enc[0];
        s[gi] = enc[1];
        s[bi] = enc[2];
        let min = TF::ENCODED_MIN;
        let max = TF::ENCODED_MAX;
        let clipped = enc[0] < min[0]
            || enc[0] > max[0]
            || enc[1] < min[1]
            || enc[1] > max[1]
            || enc[2] < min[2]
            || enc[2] > max[2]
            || enc[0].is_nan()
            || enc[1].is_nan()
            || enc[2].is_nan();
        if clipped {
            let c = |v: f32, lo: f32| if v.is_nan() { lo } else { v };
            s[ri] = c(enc[0], min[0]).clamp(min[0], max[0]);
            s[gi] = c(enc[1], min[1]).clamp(min[1], max[1]);
            s[bi] = c(enc[2], min[2]).clamp(min[2], max[2]);
            Err(OutOfGamut {
                clamped: Color::new_unchecked(glam::Vec3A::from_array(s)),
            })
        } else {
            Ok(Color::new_unchecked(glam::Vec3A::from_array(s)))
        }
    }
}

// sRGB <-> Display P3 (both use sRGB transfer function, different primaries).
impl<L> Transform<Color<[f32; 4], Srgb<L>>> for Color<[f32; 4], DisplayP3<L>>
where
    L: Asserts<[f32; 4]> + ChannelMap<4> + 'static,
{
    fn transform_from(src: Color<[f32; 4], Srgb<L>>, _: &()) -> Self {
        let s = src.inner();
        let [ri, gi, bi, _ai] = L::INDICES;
        let lin = SrgbTf::decode::<DefaultMath>([s[ri], s[gi], s[bi]]);
        let out = const { direct_matrix::<SrgbPrimaries, P3Primaries>() }.apply(lin);
        let enc = SrgbTf::encode::<DefaultMath>(out);
        let mut r = s;
        r[ri] = enc[0];
        r[gi] = enc[1];
        r[bi] = enc[2];
        Color::new_unchecked(r)
    }
}

impl<L> Transform<Color<[f32; 3], Srgb<L>>> for Color<[f32; 3], DisplayP3<L>>
where
    L: Asserts<[f32; 3]> + ChannelMap<3> + 'static,
{
    fn transform_from(src: Color<[f32; 3], Srgb<L>>, _: &()) -> Self {
        let s = src.inner();
        let [ri, gi, bi] = L::INDICES;
        let lin = SrgbTf::decode::<DefaultMath>([s[ri], s[gi], s[bi]]);
        let out = const { direct_matrix::<SrgbPrimaries, P3Primaries>() }.apply(lin);
        let enc = SrgbTf::encode::<DefaultMath>(out);
        let mut r = s;
        r[ri] = enc[0];
        r[gi] = enc[1];
        r[bi] = enc[2];
        Color::new_unchecked(r)
    }
}

impl<L> Transform<Color<[f32; 4], DisplayP3<L>>> for Color<[f32; 4], Srgb<L>>
where
    L: Asserts<[f32; 4]> + ChannelMap<4> + 'static,
{
    fn transform_from(src: Color<[f32; 4], DisplayP3<L>>, _: &()) -> Self {
        let s = src.inner();
        let [ri, gi, bi, _ai] = L::INDICES;
        let lin = SrgbTf::decode::<DefaultMath>([s[ri], s[gi], s[bi]]);
        let out = const { direct_matrix::<P3Primaries, SrgbPrimaries>() }.apply(lin);
        let enc = SrgbTf::encode::<DefaultMath>(out);
        let mut r = s;
        r[ri] = enc[0];
        r[gi] = enc[1];
        r[bi] = enc[2];
        Color::new_unchecked(r)
    }
}

impl<L> Transform<Color<[f32; 3], DisplayP3<L>>> for Color<[f32; 3], Srgb<L>>
where
    L: Asserts<[f32; 3]> + ChannelMap<3> + 'static,
{
    fn transform_from(src: Color<[f32; 3], DisplayP3<L>>, _: &()) -> Self {
        let s = src.inner();
        let [ri, gi, bi] = L::INDICES;
        let lin = SrgbTf::decode::<DefaultMath>([s[ri], s[gi], s[bi]]);
        let out = const { direct_matrix::<P3Primaries, SrgbPrimaries>() }.apply(lin);
        let enc = SrgbTf::encode::<DefaultMath>(out);
        let mut r = s;
        r[ri] = enc[0];
        r[gi] = enc[1];
        r[bi] = enc[2];
        Color::new_unchecked(r)
    }
}

// sRGB <-> Rec709 (same primaries, transfer function only).
impl<L> Transform<Color<[f32; 4], Srgb<L>>> for Color<[f32; 4], Rec709<L>>
where
    L: Asserts<[f32; 4]> + ChannelMap<4> + 'static,
{
    fn transform_from(src: Color<[f32; 4], Srgb<L>>, _: &()) -> Self {
        let s = src.inner();
        let [ri, gi, bi, _ai] = L::INDICES;
        let lin = SrgbTf::decode::<DefaultMath>([s[ri], s[gi], s[bi]]);
        let enc = Rec709Tf::encode::<DefaultMath>(lin);
        let mut r = s;
        r[ri] = enc[0];
        r[gi] = enc[1];
        r[bi] = enc[2];
        Color::new_unchecked(r)
    }
}

impl<L> Transform<Color<[f32; 3], Srgb<L>>> for Color<[f32; 3], Rec709<L>>
where
    L: Asserts<[f32; 3]> + ChannelMap<3> + 'static,
{
    fn transform_from(src: Color<[f32; 3], Srgb<L>>, _: &()) -> Self {
        let s = src.inner();
        let [ri, gi, bi] = L::INDICES;
        let lin = SrgbTf::decode::<DefaultMath>([s[ri], s[gi], s[bi]]);
        let enc = Rec709Tf::encode::<DefaultMath>(lin);
        let mut r = s;
        r[ri] = enc[0];
        r[gi] = enc[1];
        r[bi] = enc[2];
        Color::new_unchecked(r)
    }
}

impl<L> Transform<Color<[f32; 4], Rec709<L>>> for Color<[f32; 4], Srgb<L>>
where
    L: Asserts<[f32; 4]> + ChannelMap<4> + 'static,
{
    fn transform_from(src: Color<[f32; 4], Rec709<L>>, _: &()) -> Self {
        let s = src.inner();
        let [ri, gi, bi, _ai] = L::INDICES;
        let lin = Rec709Tf::decode::<DefaultMath>([s[ri], s[gi], s[bi]]);
        let enc = SrgbTf::encode::<DefaultMath>(lin);
        let mut r = s;
        r[ri] = enc[0];
        r[gi] = enc[1];
        r[bi] = enc[2];
        Color::new_unchecked(r)
    }
}

impl<L> Transform<Color<[f32; 3], Rec709<L>>> for Color<[f32; 3], Srgb<L>>
where
    L: Asserts<[f32; 3]> + ChannelMap<3> + 'static,
{
    fn transform_from(src: Color<[f32; 3], Rec709<L>>, _: &()) -> Self {
        let s = src.inner();
        let [ri, gi, bi] = L::INDICES;
        let lin = Rec709Tf::decode::<DefaultMath>([s[ri], s[gi], s[bi]]);
        let enc = SrgbTf::encode::<DefaultMath>(lin);
        let mut r = s;
        r[ri] = enc[0];
        r[gi] = enc[1];
        r[bi] = enc[2];
        Color::new_unchecked(r)
    }
}

/// Standard sRGB (IEC 61966-2-1). Web, consumer images, and the default
/// assumption when no color space is specified.
pub type Srgb<L = Rgba> = RgbSpace<SrgbPrimaries, SrgbTf, L>;
/// Linear sRGB. The correct space for premultiplied alpha compositing.
pub type LinearSrgb<L = Rgba> = RgbSpace<SrgbPrimaries, LinearTf, L>;
/// Rec. ITU-R BT.709. HD broadcast. Same primaries as sRGB, different curve.
pub type Rec709<L = Rgba> = RgbSpace<SrgbPrimaries, Rec709Tf, L>;
/// Display P3 (D65). Apple and modern Android wide-gamut displays.
/// Roughly 25% larger gamut than sRGB with the sRGB transfer function.
pub type DisplayP3<L = Rgba> = RgbSpace<P3Primaries, SrgbTf, L>;
/// Linear Display P3. Wide-gamut SDR compositing on P3-capable displays.
pub type LinearP3<L = Rgba> = RgbSpace<P3Primaries, LinearTf, L>;
/// HDR10. Rec. 2020 primaries with PQ (SMPTE ST 2084).
/// Encoded 1.0 represents 10,000 cd/m2.
pub type Hdr10<L = Rgba> = RgbSpace<Rec2020Primaries, PqTf, L>;
/// HLG (ITU-R BT.2100). Rec. 2020 with Hybrid Log-Gamma.
/// SDR-backward-compatible HDR for broadcast.
pub type Hlg<L = Rgba> = RgbSpace<Rec2020Primaries, HlgTf, L>;
/// Linear Rec. 2020. Ultra-wide gamut scene-linear compositing space.
pub type LinearRec2020<L = Rgba> = RgbSpace<Rec2020Primaries, LinearTf, L>;
/// ACEScg (AP1 linear, Academy S-2014-004). VFX and animation rendering
/// working space. All real-world colors have positive values.
pub type AcesCg<L = Rgba> = RgbSpace<AcesAp1Primaries, LinearTf, L>;
/// ACES 2065-1 (AP0 linear, SMPTE ST 2065-1). Full-gamut scene-referred
/// archival and interchange space.
pub type Aces2065<L = Rgba> = RgbSpace<AcesAp0Primaries, LinearTf, L>;
/// ACEScc (AP1 logarithmic, Academy S-2014-003). Color grading working space.
pub type AcesCc<L = Rgba> = RgbSpace<AcesAp1Primaries, AcesCcTf, L>;
/// ACEScct (AP1 quasi-logarithmic, Academy S-2016-001). Grading with toe.
pub type AcesCct<L = Rgba> = RgbSpace<AcesAp1Primaries, AcesCctTf, L>;
/// ProPhoto (ROMM RGB, ISO 22028-2). Extremely wide gamut with gamma 1.8.
/// D50 native illuminant. Used in camera raw and professional photo workflows.
pub type ProPhoto<L = Rgba> = RgbSpace<ProPhotoPrimaries, ProPhotoTf, L>;
/// Linear ProPhoto. D50 native illuminant. Lightroom internal working space.
pub type LinearProPhoto<L = Rgba> = RgbSpace<ProPhotoPrimaries, LinearTf, L>;
/// Theatrical DCI-P3 (SMPTE EG 432-1). Gamma 2.6, DCI white point.
/// Distinct from Display P3 in both white point and transfer function.
pub type DciP3<L = Rgba> = RgbSpace<DciP3Primaries, DciP3Tf, L>;
/// P3 primaries with gamma 2.6 and D65 white point. Non-standard combination.
/// Most users want DisplayP3 (sRGB curve) or DciP3 (DCI white) instead.
pub type P3D65Gamma26<L = Rgba> = RgbSpace<P3Primaries, DciP3Tf, L>;