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//! Traits for working with angular values, such as for in hues.
use crate::{
bool_mask::HasBoolMask,
num::{Real, Round},
};
#[cfg(feature = "wide")]
mod wide;
/// Represents types that can express half of a rotation (i.e. 180 degrees).
pub trait HalfRotation {
/// Return a value that represents half of a rotation (i.e. 180 degrees).
#[must_use]
fn half_rotation() -> Self;
}
/// Represents types that can express a full rotation (i.e. 360 degrees).
pub trait FullRotation {
/// Return a value that represents a full rotation (i.e. 360 degrees).
#[must_use]
fn full_rotation() -> Self;
}
/// Angle values that are real numbers and can represent both radians and
/// degrees.
pub trait RealAngle: Real {
/// Consider `self` to be radians and convert it to degrees.
#[must_use]
fn radians_to_degrees(self) -> Self;
/// Consider `self` to be degrees and convert it to radians.
#[must_use]
fn degrees_to_radians(self) -> Self;
}
/// Angular equality, where 0 degrees and 360 degrees are equal.
pub trait AngleEq: HasBoolMask {
/// Check if `self` and `other` represent the same angle on a circle.
#[must_use]
fn angle_eq(&self, other: &Self) -> Self::Mask;
}
/// Angle types that can represent the full circle using positive and negative
/// values.
pub trait SignedAngle {
/// Normalize `self` to a range corresponding to -180 to 180 degrees.
#[must_use]
fn normalize_signed_angle(self) -> Self;
}
/// Angle types that can represent the full circle as positive values.
pub trait UnsignedAngle {
/// Normalize `self` to a range corresponding to 0 to 360 degrees.
#[must_use]
fn normalize_unsigned_angle(self) -> Self;
}
/// Performs value-to-value conversion between angle types. See also [`IntoAngle`].
pub trait FromAngle<T> {
/// Performs a conversion from `angle`.
fn from_angle(angle: T) -> Self;
}
impl<T> FromAngle<T> for T {
#[inline]
fn from_angle(angle: Self) -> Self {
angle
}
}
/// Performs value-to-value conversion between angle types. See also [`IntoAngle`].
pub trait IntoAngle<T> {
/// Performs a conversion into `T`.
fn into_angle(self) -> T;
}
impl<T, U> IntoAngle<U> for T
where
U: FromAngle<T>,
{
#[inline]
fn into_angle(self) -> U {
U::from_angle(self)
}
}
macro_rules! impl_angle_float {
($($ty: ident),+) => {
$(
impl HalfRotation for $ty {
#[inline]
fn half_rotation() -> Self {
180.0
}
}
impl FullRotation for $ty {
#[inline]
fn full_rotation() -> Self {
360.0
}
}
impl RealAngle for $ty {
#[inline]
fn degrees_to_radians(self) -> Self {
self.to_radians()
}
#[inline]
fn radians_to_degrees(self) -> Self {
self.to_degrees()
}
}
impl AngleEq for $ty {
#[inline]
fn angle_eq(&self, other: &Self) -> bool {
self.normalize_unsigned_angle() == other.normalize_unsigned_angle()
}
}
impl SignedAngle for $ty {
#[inline]
fn normalize_signed_angle(self) -> Self {
self - Round::ceil(((self + 180.0) / 360.0) - 1.0) * 360.0
}
}
impl UnsignedAngle for $ty {
#[inline]
fn normalize_unsigned_angle(self) -> Self {
self - (Round::floor(self / 360.0) * 360.0)
}
}
)+
};
}
macro_rules! impl_from_angle_float {
($ty: ident to $other_ty: ident) => {
impl FromAngle<$other_ty> for $ty {
#[inline]
fn from_angle(angle: $other_ty) -> Self {
angle as $ty
}
}
};
}
macro_rules! impl_from_angle_u8 {
($($float_ty: ident),*) => {
$(
impl FromAngle<u8> for $float_ty {
#[inline]
fn from_angle(angle: u8) -> Self {
(angle as $float_ty / 256.0) * Self::full_rotation()
}
}
impl FromAngle<$float_ty> for u8 {
#[inline]
fn from_angle(angle: $float_ty) -> Self {
let normalized = angle.normalize_unsigned_angle() / $float_ty::full_rotation();
let rounded = (normalized * 256.0).round();
if rounded > 255.5 {
0
} else {
rounded as u8
}
}
}
)*
};
}
impl_angle_float!(f32, f64);
impl_from_angle_float!(f32 to f64);
impl_from_angle_float!(f64 to f32);
impl_from_angle_u8!(f32, f64);
impl HalfRotation for u8 {
#[inline]
fn half_rotation() -> Self {
128
}
}
impl AngleEq for u8 {
#[inline]
fn angle_eq(&self, other: &Self) -> bool {
self == other
}
}
impl UnsignedAngle for u8 {
#[inline]
fn normalize_unsigned_angle(self) -> Self {
self
}
}
#[cfg(test)]
mod test {
use crate::RgbHue;
#[test]
fn f32_to_u8() {
let hue_f32 = RgbHue::new(180.0f32);
let hue_u8 = hue_f32.into_format::<u8>();
assert_eq!(hue_u8, RgbHue::new(128u8));
}
#[test]
fn u8_to_f32() {
let hue_f32 = RgbHue::new(128u8);
let hue_u8 = hue_f32.into_format::<f32>();
assert_eq!(hue_u8, RgbHue::new(180.0f32));
}
}