#[cfg(feature = "serialize")]
use serde::{Deserialize, Serialize};
#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
#[cfg_attr(feature = "serialize", derive(Serialize, Deserialize))]
pub struct Rgba32 {
pub r: u8,
pub g: u8,
pub b: u8,
pub a: u8,
}
impl Rgba32 {
pub const fn new(r: u8, g: u8, b: u8, a: u8) -> Self {
Self { r, g, b, a }
}
pub const fn new_rgb(r: u8, g: u8, b: u8) -> Self {
Self { r, g, b, a: 255 }
}
pub const fn new_grey(x: u8) -> Self {
Self {
r: x,
g: x,
b: x,
a: 255,
}
}
pub const fn hex(hex: u32) -> Self {
let [a, b, g, r] = hex.to_le_bytes();
Self { r, g, b, a }
}
pub const fn hex_rgb(hex: u32) -> Self {
let [b, g, r, _] = hex.to_le_bytes();
Self { r, g, b, a: 255 }
}
pub const fn to_rgb24(self) -> crate::Rgb24 {
let Self { r, g, b, a: _ } = self;
crate::Rgb24 { r, g, b }
}
pub fn to_f32_array_01(self) -> [f32; 4] {
[
self.r as f32 / 255.,
self.g as f32 / 255.,
self.b as f32 / 255.,
self.a as f32 / 255.,
]
}
pub fn to_f32_array_rgb_01(self) -> [f32; 3] {
[
self.r as f32 / 255.,
self.g as f32 / 255.,
self.b as f32 / 255.,
]
}
pub const fn with_r(self, r: u8) -> Self {
Self { r, ..self }
}
pub const fn with_g(self, g: u8) -> Self {
Self { g, ..self }
}
pub const fn with_b(self, b: u8) -> Self {
Self { b, ..self }
}
pub const fn with_a(self, a: u8) -> Self {
Self { a, ..self }
}
pub const fn linear_interpolate(self, to: Rgba32, by: u8) -> Self {
const fn interpolate_channel(from: u8, to: u8, by: u8) -> u8 {
let total_delta = to as i32 - from as i32;
let current_delta = (total_delta * by as i32) / 255;
(from as i32 + current_delta) as u8
}
Self {
r: interpolate_channel(self.r, to.r, by),
g: interpolate_channel(self.g, to.g, by),
b: interpolate_channel(self.b, to.b, by),
a: interpolate_channel(self.a, to.a, by),
}
}
pub fn alpha_composite(self, below: Rgba32) -> Rgba32 {
fn mul_u8(a: u8, b: u8) -> u8 {
((a as u16 * b as u16) / 255) as u8
}
fn div_u8(a: u8, b: u8) -> u8 {
((255 * a as u16) / b as u16) as u8
}
let alpha_out_rhs = mul_u8(below.a, 255 - self.a);
let alpha_out = self.a + alpha_out_rhs;
let single_channel =
|c_a: u8, c_b: u8| div_u8(mul_u8(c_a, self.a) + mul_u8(c_b, alpha_out_rhs), alpha_out);
Self {
r: single_channel(self.r, below.r),
g: single_channel(self.g, below.g),
b: single_channel(self.b, below.b),
a: alpha_out,
}
}
pub const fn normalised_scalar_mul(self, scalar: u8) -> Self {
const fn single_channel(c: u8, scalar: u8) -> u8 {
((c as u32 * scalar as u32) / 255) as u8
}
Self {
r: single_channel(self.r, scalar),
g: single_channel(self.g, scalar),
b: single_channel(self.b, scalar),
a: self.a,
}
}
pub const fn saturating_scalar_mul_div(self, numerator: u32, denominator: u32) -> Self {
const fn single_channel(channel: u8, numerator: u32, denominator: u32) -> u8 {
let as_u32 = ((channel as u32) * (numerator)) / denominator;
if as_u32 > u8::MAX as u32 {
u8::MAX
} else {
as_u32 as u8
}
}
Self {
r: single_channel(self.r, numerator, denominator),
g: single_channel(self.g, numerator, denominator),
b: single_channel(self.b, numerator, denominator),
a: self.a,
}
}
pub const fn normalised_mul(self, other: Self) -> Self {
const fn single_channel(a: u8, b: u8) -> u8 {
((a as u32 * b as u32) / 255) as u8
}
Self {
r: single_channel(self.r, other.r),
g: single_channel(self.g, other.g),
b: single_channel(self.b, other.b),
a: self.a,
}
}
}
#[cfg(feature = "rand")]
mod sample {
use super::Rgba32;
use rand::distributions::uniform::{SampleBorrow, SampleUniform, UniformInt, UniformSampler};
use rand::prelude::*;
pub struct UniformRgba32LinearInterpolate {
inner: UniformInt<u8>,
low: Rgba32,
high: Rgba32,
}
impl UniformSampler for UniformRgba32LinearInterpolate {
type X = Rgba32;
fn new<B1, B2>(low: B1, high: B2) -> Self
where
B1: SampleBorrow<Self::X> + Sized,
B2: SampleBorrow<Self::X> + Sized,
{
Self {
inner: UniformInt::<u8>::new(::std::u8::MIN, u8::MAX),
low: *low.borrow(),
high: *high.borrow(),
}
}
fn new_inclusive<B1, B2>(low: B1, high: B2) -> Self
where
B1: SampleBorrow<Self::X> + Sized,
B2: SampleBorrow<Self::X> + Sized,
{
UniformSampler::new(low, high)
}
fn sample<R: Rng + ?Sized>(&self, rng: &mut R) -> Self::X {
self.low
.linear_interpolate(self.high, self.inner.sample(rng))
}
}
impl SampleUniform for Rgba32 {
type Sampler = UniformRgba32LinearInterpolate;
}
}
#[cfg(feature = "rand")]
pub use sample::UniformRgba32LinearInterpolate;
#[cfg(test)]
mod test {
use super::*;
#[test]
fn normalised_mul() {
assert_eq!(
Rgba32::new(255, 255, 255, 127).normalised_mul(Rgba32::new(1, 2, 3, 127)),
Rgba32::new(1, 2, 3, 127)
);
assert_eq!(
Rgba32::new(255, 127, 0, 127).normalised_mul(Rgba32::new(10, 20, 30, 127)),
Rgba32::new(10, 9, 0, 127)
);
}
#[test]
fn normalised_scalar_mul() {
assert_eq!(
Rgba32::new(255, 128, 0, 127).normalised_scalar_mul(128),
Rgba32::new(128, 64, 0, 127)
);
}
#[test]
fn interpolate() {
let from = Rgba32::new(0, 255, 100, 127);
let to = Rgba32::new(255, 0, 120, 127);
assert_eq!(from.linear_interpolate(to, 0), from);
assert_eq!(from.linear_interpolate(to, 255), to);
assert_eq!(
from.linear_interpolate(to, 63),
Rgba32::new(63, 192, 104, 127)
);
}
#[test]
fn hex() {
assert_eq!(Rgba32::hex(0x12345678), Rgba32::new(0x12, 0x34, 0x56, 0x78));
}
#[test]
fn hex_rgb() {
assert_eq!(Rgba32::hex_rgb(0x123456), Rgba32::new_rgb(0x12, 0x34, 0x56));
}
}