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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at https://mozilla.org/MPL/2.0/. */
//! Computed angles.
use crate::values::distance::{ComputeSquaredDistance, SquaredDistance};
use crate::values::CSSFloat;
use crate::Zero;
use std::f64::consts::PI;
use std::fmt::{self, Write};
use std::{f32, f64};
use style_traits::{CssWriter, ToCss};
/// A computed angle in degrees.
#[derive(
Add,
Animate,
Clone,
Copy,
Debug,
Deserialize,
MallocSizeOf,
PartialEq,
PartialOrd,
Serialize,
ToAnimatedZero,
ToResolvedValue,
)]
#[repr(C)]
pub struct Angle(CSSFloat);
impl ToCss for Angle {
fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
where
W: Write,
{
self.degrees().to_css(dest)?;
dest.write_str("deg")
}
}
const RAD_PER_DEG: f64 = PI / 180.0;
impl Angle {
/// Creates a computed `Angle` value from a radian amount.
pub fn from_radians(radians: CSSFloat) -> Self {
Angle(radians / RAD_PER_DEG as f32)
}
/// Creates a computed `Angle` value from a degrees amount.
#[inline]
pub fn from_degrees(degrees: CSSFloat) -> Self {
Angle(degrees)
}
/// Returns the amount of radians this angle represents.
#[inline]
pub fn radians(&self) -> CSSFloat {
self.radians64().min(f32::MAX as f64).max(f32::MIN as f64) as f32
}
/// Returns the amount of radians this angle represents as a `f64`.
///
/// Gecko stores angles as singles, but does this computation using doubles.
///
/// This is significant enough to mess up rounding to the nearest
/// quarter-turn for 225 degrees, for example.
#[inline]
pub fn radians64(&self) -> f64 {
self.0 as f64 * RAD_PER_DEG
}
/// Return the value in degrees.
#[inline]
pub fn degrees(&self) -> CSSFloat {
self.0
}
}
impl Zero for Angle {
#[inline]
fn zero() -> Self {
Angle(0.0)
}
#[inline]
fn is_zero(&self) -> bool {
self.0 == 0.
}
}
impl ComputeSquaredDistance for Angle {
#[inline]
fn compute_squared_distance(&self, other: &Self) -> Result<SquaredDistance, ()> {
// Use the formula for calculating the distance between angles defined in SVG:
// https://www.w3.org/TR/SVG/animate.html#complexDistances
self.radians64()
.compute_squared_distance(&other.radians64())
}
}
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