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|
use super::*;
/// A length that is relative to the font size.
///
/// `1em` is the same as the font size.
#[derive(Default, Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
pub struct Em(Scalar);
impl Em {
/// The zero length.
pub const fn zero() -> Self {
Self(Scalar(0.0))
}
/// The font size.
pub const fn one() -> Self {
Self(Scalar(1.0))
}
/// Create a font-relative length.
pub const fn new(em: f64) -> Self {
Self(Scalar(em))
}
/// Create font units at the given units per em.
pub fn from_units(units: impl Into<f64>, units_per_em: f64) -> Self {
Self(Scalar(units.into() / units_per_em))
}
/// Create an em length from a length at the given font size.
pub fn from_length(length: Length, font_size: Length) -> Self {
let result = length / font_size;
if result.is_finite() {
Self(Scalar(result))
} else {
Self::zero()
}
}
/// The number of em units.
pub const fn get(self) -> f64 {
(self.0).0
}
/// Convert to a length at the given font size.
pub fn at(self, font_size: Length) -> Length {
let resolved = font_size * self.get();
if resolved.is_finite() { resolved } else { Length::zero() }
}
}
impl Numeric for Em {
fn zero() -> Self {
Self::zero()
}
fn is_finite(self) -> bool {
self.0.is_finite()
}
}
impl Debug for Em {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
write!(f, "{}em", self.get())
}
}
impl Neg for Em {
type Output = Self;
fn neg(self) -> Self {
Self(-self.0)
}
}
impl Add for Em {
type Output = Self;
fn add(self, other: Self) -> Self {
Self(self.0 + other.0)
}
}
sub_impl!(Em - Em -> Em);
impl Mul<f64> for Em {
type Output = Self;
fn mul(self, other: f64) -> Self {
Self(self.0 * other)
}
}
impl Mul<Em> for f64 {
type Output = Em;
fn mul(self, other: Em) -> Em {
other * self
}
}
impl Div<f64> for Em {
type Output = Self;
fn div(self, other: f64) -> Self {
Self(self.0 / other)
}
}
impl Div for Em {
type Output = f64;
fn div(self, other: Self) -> f64 {
self.get() / other.get()
}
}
assign_impl!(Em += Em);
assign_impl!(Em -= Em);
assign_impl!(Em *= f64);
assign_impl!(Em /= f64);
impl Sum for Em {
fn sum<I: Iterator<Item = Self>>(iter: I) -> Self {
Self(iter.map(|s| s.0).sum())
}
}
|
