style/values/specified/
resolution.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//! Resolution values:
6//!
7//! https://drafts.csswg.org/css-values/#resolution
8
9use crate::derives::*;
10use crate::parser::{Parse, ParserContext};
11use crate::values::computed::resolution::Resolution as ComputedResolution;
12use crate::values::computed::{Context, ToComputedValue};
13use crate::values::specified::calc::{CalcNode, CalcNumeric, Leaf};
14use crate::values::tagged_numeric::{NumericUnion, Unpacked};
15use crate::values::CSSFloat;
16use cssparser::{match_ignore_ascii_case, Parser, Token};
17use std::fmt::{self, Write};
18use style_traits::{CssWriter, ParseError, SpecifiedValueInfo, StyleParseErrorKind, ToCss};
19
20/// The unit of a `<resolution>` value.
21#[derive(Clone, Copy, Debug, MallocSizeOf, PartialEq, SpecifiedValueInfo, ToCss, ToShmem)]
22#[repr(u8)]
23pub enum ResolutionUnit {
24    /// Dots per inch.
25    Dpi,
26    /// An alias unit for dots per pixel.
27    X,
28    /// Dots per pixel.
29    Dppx,
30    /// Dots per centimeter.
31    Dpcm,
32}
33
34impl ResolutionUnit {
35    /// Returns this unit as a string.
36    #[inline]
37    pub fn as_str(self) -> &'static str {
38        match self {
39            Self::Dpi => "dpi",
40            Self::X => "x",
41            Self::Dppx => "dppx",
42            Self::Dpcm => "dpcm",
43        }
44    }
45}
46
47/// A non-calc `<resolution>` value.
48#[derive(Clone, Copy, Debug, MallocSizeOf, PartialEq, ToShmem)]
49#[repr(C)]
50pub struct NoCalcResolution {
51    unit: ResolutionUnit,
52    value: CSSFloat,
53}
54
55impl NoCalcResolution {
56    /// Creates a resolution with the given unit and value.
57    #[inline]
58    pub fn new(unit: ResolutionUnit, value: CSSFloat) -> Self {
59        Self { unit, value }
60    }
61
62    /// Returns a resolution value from dppx units.
63    #[inline]
64    pub fn from_dppx(value: CSSFloat) -> Self {
65        Self::new(ResolutionUnit::Dppx, value)
66    }
67
68    /// Returns a resolution value from x units.
69    #[inline]
70    pub fn from_x(value: CSSFloat) -> Self {
71        Self::new(ResolutionUnit::X, value)
72    }
73
74    /// Convert this resolution value to dppx units.
75    pub fn dppx(&self) -> CSSFloat {
76        match self.unit {
77            ResolutionUnit::X | ResolutionUnit::Dppx => self.value,
78            _ => self.dpi() / 96.0,
79        }
80    }
81
82    /// Convert this resolution value to dpi units.
83    pub fn dpi(&self) -> CSSFloat {
84        match self.unit {
85            ResolutionUnit::Dpi => self.value,
86            ResolutionUnit::X | ResolutionUnit::Dppx => self.value * 96.0,
87            ResolutionUnit::Dpcm => self.value * 2.54,
88        }
89    }
90
91    /// Returns the unit of the resolution.
92    #[inline]
93    pub fn resolution_unit(&self) -> ResolutionUnit {
94        self.unit
95    }
96
97    /// Parse a resolution given a value and unit.
98    pub fn parse_dimension(value: CSSFloat, unit: &str) -> Result<Self, ()> {
99        let unit = match_ignore_ascii_case! { &unit,
100            "dpi" => ResolutionUnit::Dpi,
101            "dppx" => ResolutionUnit::Dppx,
102            "dpcm" => ResolutionUnit::Dpcm,
103            "x" => ResolutionUnit::X,
104            _ => return Err(())
105        };
106        Ok(Self::new(unit, value))
107    }
108}
109
110impl ToCss for NoCalcResolution {
111    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
112    where
113        W: Write,
114    {
115        crate::values::serialize_specified_dimension(
116            self.value,
117            self.unit.as_str(),
118            /* was_calc = */ false,
119            dest,
120        )
121    }
122}
123
124impl SpecifiedValueInfo for NoCalcResolution {}
125
126/// A specified resolution value, either a plain value or a `calc()` expression.
127///
128/// https://drafts.csswg.org/css-values/#resolution-value
129#[derive(Clone, Debug, MallocSizeOf, PartialEq, ToShmem)]
130pub struct Resolution(NumericUnion<ResolutionUnit, f32, CalcNumeric>);
131
132impl ToCss for Resolution {
133    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
134    where
135        W: Write,
136    {
137        match self.0.unpack() {
138            Unpacked::Inline(unit, value) => NoCalcResolution::new(unit, value).to_css(dest),
139            Unpacked::Boxed(calc) => calc.to_css(dest),
140        }
141    }
142}
143
144impl SpecifiedValueInfo for Resolution {}
145
146impl Resolution {
147    /// Creates a resolution from a non-calc `NoCalcResolution`.
148    #[inline]
149    pub fn new(resolution: NoCalcResolution) -> Self {
150        Self(NumericUnion::inline(resolution.unit, resolution.value))
151    }
152
153    /// Creates a resolution from a `calc()` expression.
154    #[inline]
155    pub fn new_calc(calc: Box<CalcNumeric>) -> Self {
156        Self(NumericUnion::boxed(calc))
157    }
158
159    /// Returns a resolution value from dppx units.
160    #[inline]
161    pub fn from_dppx(value: CSSFloat) -> Self {
162        Self::new(NoCalcResolution::from_dppx(value))
163    }
164
165    /// Returns a resolution value from x units.
166    #[inline]
167    pub fn from_x(value: CSSFloat) -> Self {
168        Self::new(NoCalcResolution::from_x(value))
169    }
170
171    /// Returns true if this is a `calc()` expression.
172    #[inline]
173    pub fn is_calc(&self) -> bool {
174        self.0.is_boxed()
175    }
176
177    /// Parse a resolution given a value and unit.
178    pub fn parse_dimension(value: CSSFloat, unit: &str) -> Result<Self, ()> {
179        NoCalcResolution::parse_dimension(value, unit).map(Self::new)
180    }
181}
182
183impl ToComputedValue for Resolution {
184    type ComputedValue = ComputedResolution;
185
186    #[inline]
187    fn to_computed_value(&self, context: &Context) -> Self::ComputedValue {
188        let dppx = match self.0.unpack() {
189            Unpacked::Inline(unit, value) => NoCalcResolution::new(unit, value).dppx().max(0.0),
190            Unpacked::Boxed(calc) => calc.resolve(context, |result| match result {
191                Ok(Leaf::Resolution(r)) => r.dppx().max(0.0),
192                _ => {
193                    debug_assert!(
194                        false,
195                        "Unexpected Resolution::Calc without resolved resolution"
196                    );
197                    0.0
198                },
199            }),
200        };
201        ComputedResolution::from_dppx(crate::values::normalize(dppx))
202    }
203
204    #[inline]
205    fn from_computed_value(computed: &Self::ComputedValue) -> Self {
206        Self::from_dppx(computed.dppx())
207    }
208}
209
210impl Parse for Resolution {
211    fn parse<'i, 't>(
212        context: &ParserContext,
213        input: &mut Parser<'i, 't>,
214    ) -> Result<Self, ParseError<'i>> {
215        let location = input.current_source_location();
216        match *input.next()? {
217            Token::Dimension {
218                value, ref unit, ..
219            } if value >= 0. => Self::parse_dimension(value, unit)
220                .map_err(|()| location.new_custom_error(StyleParseErrorKind::UnspecifiedError)),
221            Token::Function(ref name) => {
222                let function = CalcNode::math_function(context, name, location)?;
223                CalcNode::parse_resolution(context, input, function)
224                    .map(Box::new)
225                    .map(Self::new_calc)
226            },
227            ref t => return Err(location.new_unexpected_token_error(t.clone())),
228        }
229    }
230}
style/values/specified/resolution.rs

style/values/specified/
resolution.rs
