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use num_traits::Zero;
use crate::float::Float;
use crate::{clamp, FromF64};
pub trait Component: Copy + Zero + PartialOrd {
fn max_intensity() -> Self;
}
pub trait FloatComponent: Component + Float + FromF64 {}
impl<T: Component + Float + FromF64> FloatComponent for T {}
macro_rules! impl_float_components {
($($ty: ident),+) => {
$(
impl Component for $ty {
fn max_intensity() -> Self {
1.0
}
}
)*
};
}
impl_float_components!(f32, f64);
macro_rules! impl_uint_components {
($($ty: ident),+) => {
$(
impl Component for $ty {
fn max_intensity() -> Self {
core::$ty::MAX
}
}
)*
};
}
impl_uint_components!(u8, u16, u32, u64, u128);
pub trait FromComponent<T: Component> {
fn from_component(other: T) -> Self;
}
impl<T: Component, U: IntoComponent<T> + Component> FromComponent<U> for T {
#[inline]
fn from_component(other: U) -> T {
other.into_component()
}
}
pub trait IntoComponent<T: Component> {
fn into_component(self) -> T;
}
impl<T: Component> IntoComponent<T> for T {
#[inline]
fn into_component(self) -> T {
self
}
}
const C23: u32 = 0x4b00_0000;
const C52: u64 = 0x4330_0000_0000_0000;
macro_rules! convert_float_to_uint {
($float: ident; direct ($($direct_target: ident),+); $(via $temporary: ident ($($target: ident),+);)*) => {
$(
impl IntoComponent<$direct_target> for $float {
#[inline]
fn into_component(self) -> $direct_target {
let max = $direct_target::max_intensity() as $float;
let scaled = (self * max).min(max);
let f = scaled + f32::from_bits(C23);
(f.to_bits().saturating_sub(C23)) as $direct_target
}
}
)+
$(
$(
impl IntoComponent<$target> for $float {
#[inline]
fn into_component(self) -> $target {
let max = $target::max_intensity() as $temporary;
let scaled = (self as $temporary * max).min(max);
let f = scaled + f64::from_bits(C52);
(f.to_bits().saturating_sub(C52)) as $target
}
}
)+
)*
};
}
macro_rules! convert_double_to_uint {
($double: ident; direct ($($direct_target: ident),+);) => {
$(
impl IntoComponent<$direct_target> for $double {
#[inline]
fn into_component(self) -> $direct_target {
let max = $direct_target::max_intensity() as $double;
let scaled = (self * max).min(max);
let f = scaled + f64::from_bits(C52);
(f.to_bits().saturating_sub(C52)) as $direct_target
}
}
)+
};
}
impl IntoComponent<f32> for u8 {
#[inline]
fn into_component(self) -> f32 {
let comp_u = u32::from(self) + C23;
let comp_f = f32::from_bits(comp_u) - f32::from_bits(C23);
let max_u = u32::from(core::u8::MAX) + C23;
let max_f = (f32::from_bits(max_u) - f32::from_bits(C23)).recip();
comp_f * max_f
}
}
impl IntoComponent<f64> for u8 {
#[inline]
fn into_component(self) -> f64 {
let comp_u = u64::from(self) + C52;
let comp_f = f64::from_bits(comp_u) - f64::from_bits(C52);
let max_u = u64::from(core::u8::MAX) + C52;
let max_f = (f64::from_bits(max_u) - f64::from_bits(C52)).recip();
comp_f * max_f
}
}
macro_rules! convert_uint_to_float {
($uint: ident; $(via $temporary: ident ($($target: ident),+);)*) => {
$(
$(
impl IntoComponent<$target> for $uint {
#[inline]
fn into_component(self) -> $target {
let max = $uint::max_intensity() as $temporary;
let scaled = self as $temporary / max;
scaled as $target
}
}
)+
)*
};
}
macro_rules! convert_uint_to_uint {
($uint: ident; $(via $temporary: ident ($($target: ident),+);)*) => {
$(
$(
impl IntoComponent<$target> for $uint {
#[inline]
fn into_component(self) -> $target {
let target_max = $target::max_intensity() as $temporary;
let own_max = $uint::max_intensity() as $temporary;
let scaled = (self as $temporary / own_max) * target_max;
clamp(scaled.round(), 0.0, target_max) as $target
}
}
)+
)*
};
}
impl IntoComponent<f64> for f32 {
#[inline]
fn into_component(self) -> f64 {
f64::from(self)
}
}
convert_float_to_uint!(f32; direct (u8, u16); via f64 (u32, u64, u128););
impl IntoComponent<f32> for f64 {
#[inline]
fn into_component(self) -> f32 {
self as f32
}
}
convert_double_to_uint!(f64; direct (u8, u16, u32, u64, u128););
convert_uint_to_uint!(u8; via f32 (u16); via f64 (u32, u64, u128););
convert_uint_to_float!(u16; via f32 (f32); via f64 (f64););
convert_uint_to_uint!(u16; via f32 (u8); via f64 (u32, u64, u128););
convert_uint_to_float!(u32; via f64 (f32, f64););
convert_uint_to_uint!(u32; via f64 (u8, u16, u64, u128););
convert_uint_to_float!(u64; via f64 (f32, f64););
convert_uint_to_uint!(u64; via f64 (u8, u16, u32, u128););
convert_uint_to_float!(u128; via f64 (f32, f64););
convert_uint_to_uint!(u128; via f64 (u8, u16, u32, u64););
#[cfg(test)]
mod test {
use crate::IntoComponent;
use approx::assert_relative_eq;
#[test]
fn float_to_uint() {
let data = vec![
-800.0,
-0.3,
0.0,
0.005,
0.024983,
0.01,
0.15,
0.3,
0.5,
0.6,
0.7,
0.8,
0.8444,
0.9,
0.955,
0.999,
1.0,
1.4,
f32::from_bits(0x4b44_0000),
std::f32::MAX,
std::f32::MIN,
std::f32::NAN,
std::f32::INFINITY,
std::f32::NEG_INFINITY,
];
let expected = vec![
0u8, 0, 0, 1, 6, 3, 38, 76, 128, 153, 178, 204, 215, 230, 244, 255, 255, 255, 255, 255,
0, 255, 255, 0,
];
for (d, e) in data.into_iter().zip(expected) {
assert_eq!(IntoComponent::<u8>::into_component(d), e);
}
}
#[test]
fn double_to_uint() {
let data = vec![
-800.0,
-0.3,
0.0,
0.005,
0.024983,
0.01,
0.15,
0.3,
0.5,
0.6,
0.7,
0.8,
0.8444,
0.9,
0.955,
0.999,
1.0,
1.4,
f64::from_bits(0x4334_0000_0000_0000),
std::f64::MAX,
std::f64::MIN,
std::f64::NAN,
std::f64::INFINITY,
std::f64::NEG_INFINITY,
];
let expected = vec![
0u8, 0, 0, 1, 6, 3, 38, 76, 128, 153, 178, 204, 215, 230, 244, 255, 255, 255, 255, 255,
0, 255, 255, 0,
];
for (d, e) in data.into_iter().zip(expected) {
assert_eq!(IntoComponent::<u8>::into_component(d), e);
}
}
#[test]
fn uint_to_float() {
fn into_component_old(n: u8) -> f32 {
let max = core::u8::MAX as f32;
let scaled = n as f32 / max;
scaled as f32
}
for n in (0..=255).step_by(5) {
assert_relative_eq!(
IntoComponent::<f32>::into_component(n),
into_component_old(n)
)
}
}
#[test]
fn uint_to_double() {
fn into_component_old(n: u8) -> f64 {
let max = core::u8::MAX as f64;
let scaled = n as f64 / max;
scaled as f64
}
for n in (0..=255).step_by(5) {
assert_relative_eq!(
IntoComponent::<f64>::into_component(n),
into_component_old(n)
)
}
}
}