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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/. */
//! Resolution values:
//!
//! https://drafts.csswg.org/css-values/#resolution
use crate::parser::{Parse, ParserContext};
use crate::values::specified::CalcNode;
use crate::values::CSSFloat;
use cssparser::{Parser, Token};
use std::fmt::{self, Write};
use style_traits::{CssWriter, ParseError, StyleParseErrorKind, ToCss};
/// A specified resolution.
#[derive(Clone, Debug, MallocSizeOf, PartialEq, SpecifiedValueInfo, ToShmem)]
pub struct Resolution {
value: CSSFloat,
unit: ResolutionUnit,
was_calc: bool,
}
#[derive(Clone, Copy, Debug, MallocSizeOf, PartialEq, SpecifiedValueInfo, ToCss, ToShmem)]
enum ResolutionUnit {
/// Dots per inch.
Dpi,
/// An alias unit for dots per pixel.
X,
/// Dots per pixel.
Dppx,
/// Dots per centimeter.
Dpcm,
}
impl ResolutionUnit {
fn as_str(self) -> &'static str {
match self {
Self::Dpi => "dpi",
Self::X => "x",
Self::Dppx => "dppx",
Self::Dpcm => "dpcm",
}
}
}
impl Resolution {
/// Returns a resolution value from dppx units.
pub fn from_dppx(value: CSSFloat) -> Self {
Self {
value,
unit: ResolutionUnit::Dppx,
was_calc: false,
}
}
/// Returns a resolution value from dppx units.
pub fn from_x(value: CSSFloat) -> Self {
Self {
value,
unit: ResolutionUnit::X,
was_calc: false,
}
}
/// Returns a resolution value from dppx units.
pub fn from_dppx_calc(value: CSSFloat) -> Self {
Self {
value,
unit: ResolutionUnit::Dppx,
was_calc: true,
}
}
/// Convert this resolution value to dppx units.
pub fn dppx(&self) -> CSSFloat {
match self.unit {
ResolutionUnit::X | ResolutionUnit::Dppx => self.value,
_ => self.dpi() / 96.0,
}
}
/// Convert this resolution value to dpi units.
pub fn dpi(&self) -> CSSFloat {
match self.unit {
ResolutionUnit::Dpi => self.value,
ResolutionUnit::X | ResolutionUnit::Dppx => self.value * 96.0,
ResolutionUnit::Dpcm => self.value * 2.54,
}
}
/// Parse a resolution given a value and unit.
pub fn parse_dimension<'i, 't>(value: CSSFloat, unit: &str) -> Result<Self, ()> {
let unit = match_ignore_ascii_case! { &unit,
"dpi" => ResolutionUnit::Dpi,
"dppx" => ResolutionUnit::Dppx,
"dpcm" => ResolutionUnit::Dpcm,
"x" => ResolutionUnit::X,
_ => return Err(())
};
Ok(Self {
value,
unit,
was_calc: false,
})
}
}
impl ToCss for Resolution {
fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
where
W: Write,
{
crate::values::serialize_specified_dimension(
self.value,
self.unit.as_str(),
self.was_calc,
dest,
)
}
}
impl Parse for Resolution {
fn parse<'i, 't>(
context: &ParserContext,
input: &mut Parser<'i, 't>,
) -> Result<Self, ParseError<'i>> {
let location = input.current_source_location();
match *input.next()? {
Token::Dimension {
value, ref unit, ..
} if value >= 0. => Self::parse_dimension(value, unit)
.map_err(|()| location.new_custom_error(StyleParseErrorKind::UnspecifiedError)),
Token::Function(ref name) => {
let function = CalcNode::math_function(context, name, location)?;
CalcNode::parse_resolution(context, input, function)
},
ref t => return Err(location.new_unexpected_token_error(t.clone())),
}
}
}
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