style/values/generics/
ratio.rs

1/* This Source Code Form is subject to the terms of the Mozilla Public
2 * License, v. 2.0. If a copy of the MPL was not distributed with this
3 * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
4
5//! Generic types for CSS values related to <ratio>.
6//! https://drafts.csswg.org/css-values/#ratios
7
8use crate::{One, Zero};
9use std::fmt::{self, Write};
10use style_traits::{CssWriter, ToCss};
11
12/// A generic value for the `<ratio>` value.
13#[derive(
14    Clone,
15    Copy,
16    Debug,
17    MallocSizeOf,
18    PartialEq,
19    SpecifiedValueInfo,
20    ToAnimatedValue,
21    ToComputedValue,
22    ToResolvedValue,
23    ToShmem,
24)]
25#[repr(C)]
26pub struct Ratio<N>(pub N, pub N);
27
28impl<N> ToCss for Ratio<N>
29where
30    N: ToCss,
31{
32    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
33    where
34        W: Write,
35    {
36        self.0.to_css(dest)?;
37        // Even though 1 could be omitted, we don't per
38        // https://drafts.csswg.org/css-values-4/#ratio-value:
39        //
40        //     The second <number> is optional, defaulting to 1. However,
41        //     <ratio> is always serialized with both components.
42        //
43        // And for compat reasons, see bug 1669742.
44        //
45        // We serialize with spaces for consistency with all other
46        // slash-delimited things, see
47        // https://github.com/w3c/csswg-drafts/issues/4282
48        dest.write_str(" / ")?;
49        self.1.to_css(dest)?;
50        Ok(())
51    }
52}
53
54impl<N> Ratio<N>
55where
56    N: Zero + One,
57{
58    /// Returns true if this is a degenerate ratio.
59    /// https://drafts.csswg.org/css-values/#degenerate-ratio
60    #[inline]
61    pub fn is_degenerate(&self) -> bool {
62        self.0.is_zero() || self.1.is_zero()
63    }
64
65    /// Returns the used value. A ratio of 0/0 behaves as the ratio 1/0.
66    /// https://drafts.csswg.org/css-values-4/#ratios
67    pub fn used_value(self) -> Self {
68        if self.0.is_zero() && self.1.is_zero() {
69            Self(One::one(), Zero::zero())
70        } else {
71            self
72        }
73    }
74}
75
76impl<N> Zero for Ratio<N>
77where
78    N: Zero + One,
79{
80    fn zero() -> Self {
81        Self(Zero::zero(), One::one())
82    }
83
84    fn is_zero(&self) -> bool {
85        self.0.is_zero()
86    }
87}
style/values/generics/ratio.rs

style/values/generics/
ratio.rs
