tor-browser

The Tor Browser
git clone https://git.dasho.dev/tor-browser.git
Log | Files | Refs | README | LICENSE

ratio.rs (2231B)

      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 
      8 use crate::derives::*;
      9 use crate::{One, Zero};
     10 use std::fmt::{self, Write};
     11 use style_traits::{CssWriter, ToCss};
     12 
     13 /// A generic value for the `<ratio>` value.
     14 #[derive(
     15    Clone,
     16    Copy,
     17    Debug,
     18    MallocSizeOf,
     19    PartialEq,
     20    SpecifiedValueInfo,
     21    ToAnimatedValue,
     22    ToComputedValue,
     23    ToResolvedValue,
     24    ToShmem,
     25 )]
     26 #[repr(C)]
     27 pub struct Ratio<N>(pub N, pub N);
     28 
     29 impl<N> ToCss for Ratio<N>
     30 where
     31    N: ToCss,
     32 {
     33    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
     34    where
     35        W: Write,
     36    {
     37        self.0.to_css(dest)?;
     38        // Even though 1 could be omitted, we don't per
     39        // https://drafts.csswg.org/css-values-4/#ratio-value:
     40        //
     41        //     The second <number> is optional, defaulting to 1. However,
     42        //     <ratio> is always serialized with both components.
     43        //
     44        // And for compat reasons, see bug 1669742.
     45        //
     46        // We serialize with spaces for consistency with all other
     47        // slash-delimited things, see
     48        // https://github.com/w3c/csswg-drafts/issues/4282
     49        dest.write_str(" / ")?;
     50        self.1.to_css(dest)?;
     51        Ok(())
     52    }
     53 }
     54 
     55 impl<N> Ratio<N>
     56 where
     57    N: Zero + One,
     58 {
     59    /// Returns true if this is a degenerate ratio.
     60    /// https://drafts.csswg.org/css-values/#degenerate-ratio
     61    #[inline]
     62    pub fn is_degenerate(&self) -> bool {
     63        self.0.is_zero() || self.1.is_zero()
     64    }
     65 
     66    /// Returns the used value. A ratio of 0/0 behaves as the ratio 1/0.
     67    /// https://drafts.csswg.org/css-values-4/#ratios
     68    pub fn used_value(self) -> Self {
     69        if self.0.is_zero() && self.1.is_zero() {
     70            Self(One::one(), Zero::zero())
     71        } else {
     72            self
     73        }
     74    }
     75 }
     76 
     77 impl<N> Zero for Ratio<N>
     78 where
     79    N: Zero + One,
     80 {
     81    fn zero() -> Self {
     82        Self(Zero::zero(), One::one())
     83    }
     84 
     85    fn is_zero(&self) -> bool {
     86        self.0.is_zero()
     87    }
     88 }