Split out ecolor crate (#2399)

* split out ecolor crate

* split up ecolor crate in lots of modules

* add changelog notes

* add readme to ecolor

* put clippy::manual_range_contains on cranky allow list

* fix hex color issues

* doc fixes

* more hex_color fixes

* Document features

* Rename hex_color module to avoid warning

* Sort the feature names

* fix link in CHANGELOG.md

* better wording

Co-authored-by: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>

crates/ecolor/src/rgba.rs

@@ -0,0 +1,266 @@
+use crate::{
+    gamma_u8_from_linear_f32, linear_f32_from_gamma_u8, linear_f32_from_linear_u8,
+    linear_u8_from_linear_f32,
+};
+
+/// 0-1 linear space `RGBA` color with premultiplied alpha.
+#[repr(C)]
+#[derive(Clone, Copy, Debug, Default, PartialEq)]
+#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
+#[cfg_attr(feature = "bytemuck", derive(bytemuck::Pod, bytemuck::Zeroable))]
+pub struct Rgba(pub(crate) [f32; 4]);
+
+impl std::ops::Index<usize> for Rgba {
+    type Output = f32;
+
+    #[inline(always)]
+    fn index(&self, index: usize) -> &f32 {
+        &self.0[index]
+    }
+}
+
+impl std::ops::IndexMut<usize> for Rgba {
+    #[inline(always)]
+    fn index_mut(&mut self, index: usize) -> &mut f32 {
+        &mut self.0[index]
+    }
+}
+
+#[inline(always)]
+pub(crate) fn f32_hash<H: std::hash::Hasher>(state: &mut H, f: f32) {
+    if f == 0.0 {
+        state.write_u8(0);
+    } else if f.is_nan() {
+        state.write_u8(1);
+    } else {
+        use std::hash::Hash;
+        f.to_bits().hash(state);
+    }
+}
+
+#[allow(clippy::derive_hash_xor_eq)]
+impl std::hash::Hash for Rgba {
+    #[inline]
+    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
+        crate::f32_hash(state, self.0[0]);
+        crate::f32_hash(state, self.0[1]);
+        crate::f32_hash(state, self.0[2]);
+        crate::f32_hash(state, self.0[3]);
+    }
+}
+
+impl Rgba {
+    pub const TRANSPARENT: Rgba = Rgba::from_rgba_premultiplied(0.0, 0.0, 0.0, 0.0);
+    pub const BLACK: Rgba = Rgba::from_rgb(0.0, 0.0, 0.0);
+    pub const WHITE: Rgba = Rgba::from_rgb(1.0, 1.0, 1.0);
+    pub const RED: Rgba = Rgba::from_rgb(1.0, 0.0, 0.0);
+    pub const GREEN: Rgba = Rgba::from_rgb(0.0, 1.0, 0.0);
+    pub const BLUE: Rgba = Rgba::from_rgb(0.0, 0.0, 1.0);
+
+    #[inline(always)]
+    pub const fn from_rgba_premultiplied(r: f32, g: f32, b: f32, a: f32) -> Self {
+        Self([r, g, b, a])
+    }
+
+    #[inline(always)]
+    pub fn from_rgba_unmultiplied(r: f32, g: f32, b: f32, a: f32) -> Self {
+        Self([r * a, g * a, b * a, a])
+    }
+
+    #[inline(always)]
+    pub fn from_srgba_premultiplied(r: u8, g: u8, b: u8, a: u8) -> Self {
+        let r = linear_f32_from_gamma_u8(r);
+        let g = linear_f32_from_gamma_u8(g);
+        let b = linear_f32_from_gamma_u8(b);
+        let a = linear_f32_from_linear_u8(a);
+        Self::from_rgba_premultiplied(r, g, b, a)
+    }
+
+    #[inline(always)]
+    pub fn from_srgba_unmultiplied(r: u8, g: u8, b: u8, a: u8) -> Self {
+        let r = linear_f32_from_gamma_u8(r);
+        let g = linear_f32_from_gamma_u8(g);
+        let b = linear_f32_from_gamma_u8(b);
+        let a = linear_f32_from_linear_u8(a);
+        Self::from_rgba_premultiplied(r * a, g * a, b * a, a)
+    }
+
+    #[inline(always)]
+    pub const fn from_rgb(r: f32, g: f32, b: f32) -> Self {
+        Self([r, g, b, 1.0])
+    }
+
+    #[inline(always)]
+    pub const fn from_gray(l: f32) -> Self {
+        Self([l, l, l, 1.0])
+    }
+
+    pub fn from_luminance_alpha(l: f32, a: f32) -> Self {
+        crate::ecolor_assert!(0.0 <= l && l <= 1.0);
+        crate::ecolor_assert!(0.0 <= a && a <= 1.0);
+        Self([l * a, l * a, l * a, a])
+    }
+
+    /// Transparent black
+    #[inline(always)]
+    pub fn from_black_alpha(a: f32) -> Self {
+        crate::ecolor_assert!(0.0 <= a && a <= 1.0);
+        Self([0.0, 0.0, 0.0, a])
+    }
+
+    /// Transparent white
+    #[inline(always)]
+    pub fn from_white_alpha(a: f32) -> Self {
+        crate::ecolor_assert!(0.0 <= a && a <= 1.0, "a: {}", a);
+        Self([a, a, a, a])
+    }
+
+    /// Return an additive version of this color (alpha = 0)
+    #[inline(always)]
+    pub fn additive(self) -> Self {
+        let [r, g, b, _] = self.0;
+        Self([r, g, b, 0.0])
+    }
+
+    /// Multiply with e.g. 0.5 to make us half transparent
+    #[inline(always)]
+    pub fn multiply(self, alpha: f32) -> Self {
+        Self([
+            alpha * self[0],
+            alpha * self[1],
+            alpha * self[2],
+            alpha * self[3],
+        ])
+    }
+
+    #[inline(always)]
+    pub fn r(&self) -> f32 {
+        self.0[0]
+    }
+
+    #[inline(always)]
+    pub fn g(&self) -> f32 {
+        self.0[1]
+    }
+
+    #[inline(always)]
+    pub fn b(&self) -> f32 {
+        self.0[2]
+    }
+
+    #[inline(always)]
+    pub fn a(&self) -> f32 {
+        self.0[3]
+    }
+
+    /// How perceptually intense (bright) is the color?
+    #[inline]
+    pub fn intensity(&self) -> f32 {
+        0.3 * self.r() + 0.59 * self.g() + 0.11 * self.b()
+    }
+
+    /// Returns an opaque version of self
+    pub fn to_opaque(&self) -> Self {
+        if self.a() == 0.0 {
+            // Additive or fully transparent black.
+            Self::from_rgb(self.r(), self.g(), self.b())
+        } else {
+            // un-multiply alpha:
+            Self::from_rgb(
+                self.r() / self.a(),
+                self.g() / self.a(),
+                self.b() / self.a(),
+            )
+        }
+    }
+
+    /// Premultiplied RGBA
+    #[inline(always)]
+    pub fn to_array(&self) -> [f32; 4] {
+        [self.r(), self.g(), self.b(), self.a()]
+    }
+
+    /// Premultiplied RGBA
+    #[inline(always)]
+    pub fn to_tuple(&self) -> (f32, f32, f32, f32) {
+        (self.r(), self.g(), self.b(), self.a())
+    }
+
+    /// unmultiply the alpha
+    pub fn to_rgba_unmultiplied(&self) -> [f32; 4] {
+        let a = self.a();
+        if a == 0.0 {
+            // Additive, let's assume we are black
+            self.0
+        } else {
+            [self.r() / a, self.g() / a, self.b() / a, a]
+        }
+    }
+
+    /// unmultiply the alpha
+    pub fn to_srgba_unmultiplied(&self) -> [u8; 4] {
+        let [r, g, b, a] = self.to_rgba_unmultiplied();
+        [
+            gamma_u8_from_linear_f32(r),
+            gamma_u8_from_linear_f32(g),
+            gamma_u8_from_linear_f32(b),
+            linear_u8_from_linear_f32(a.abs()),
+        ]
+    }
+}
+
+impl std::ops::Add for Rgba {
+    type Output = Rgba;
+
+    #[inline(always)]
+    fn add(self, rhs: Rgba) -> Rgba {
+        Rgba([
+            self[0] + rhs[0],
+            self[1] + rhs[1],
+            self[2] + rhs[2],
+            self[3] + rhs[3],
+        ])
+    }
+}
+
+impl std::ops::Mul<Rgba> for Rgba {
+    type Output = Rgba;
+
+    #[inline(always)]
+    fn mul(self, other: Rgba) -> Rgba {
+        Rgba([
+            self[0] * other[0],
+            self[1] * other[1],
+            self[2] * other[2],
+            self[3] * other[3],
+        ])
+    }
+}
+
+impl std::ops::Mul<f32> for Rgba {
+    type Output = Rgba;
+
+    #[inline(always)]
+    fn mul(self, factor: f32) -> Rgba {
+        Rgba([
+            self[0] * factor,
+            self[1] * factor,
+            self[2] * factor,
+            self[3] * factor,
+        ])
+    }
+}
+
+impl std::ops::Mul<Rgba> for f32 {
+    type Output = Rgba;
+
+    #[inline(always)]
+    fn mul(self, rgba: Rgba) -> Rgba {
+        Rgba([
+            self * rgba[0],
+            self * rgba[1],
+            self * rgba[2],
+            self * rgba[3],
+        ])
+    }
+}