/* 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/. */
//! Specified angles.
use crate::parser::{Parse, ParserContext};
use crate::values::computed::angle::Angle as ComputedAngle;
use crate::values::computed::{Context, ToComputedValue};
use crate::values::specified::calc::CalcNode;
use crate::values::CSSFloat;
use crate::Zero;
use cssparser::{Parser, Token};
use std::f32::consts::PI;
use std::fmt::{self, Write};
use style_traits::{CssWriter, ParseError, SpecifiedValueInfo, ToCss};
/// A specified angle dimension.
#[cfg_attr(feature = "servo", derive(Deserialize, Serialize))]
#[derive(Clone, Copy, Debug, MallocSizeOf, PartialEq, PartialOrd, ToCss, ToShmem)]
pub enum AngleDimension {
/// An angle with degree unit.
#[css(dimension)]
Deg(CSSFloat),
/// An angle with gradian unit.
#[css(dimension)]
Grad(CSSFloat),
/// An angle with radian unit.
#[css(dimension)]
Rad(CSSFloat),
/// An angle with turn unit.
#[css(dimension)]
Turn(CSSFloat),
}
impl Zero for AngleDimension {
fn zero() -> Self {
AngleDimension::Deg(0.)
}
fn is_zero(&self) -> bool {
self.unitless_value() == 0.0
}
}
impl AngleDimension {
/// Returns the amount of degrees this angle represents.
#[inline]
fn degrees(&self) -> CSSFloat {
const DEG_PER_RAD: f32 = 180.0 / PI;
const DEG_PER_TURN: f32 = 360.0;
const DEG_PER_GRAD: f32 = 180.0 / 200.0;
match *self {
AngleDimension::Deg(d) => d,
AngleDimension::Rad(rad) => rad * DEG_PER_RAD,
AngleDimension::Turn(turns) => turns * DEG_PER_TURN,
AngleDimension::Grad(gradians) => gradians * DEG_PER_GRAD,
}
}
fn unitless_value(&self) -> CSSFloat {
match *self {
AngleDimension::Deg(v) |
AngleDimension::Rad(v) |
AngleDimension::Turn(v) |
AngleDimension::Grad(v) => v,
}
}
fn unit(&self) -> &'static str {
match *self {
AngleDimension::Deg(_) => "deg",
AngleDimension::Rad(_) => "rad",
AngleDimension::Turn(_) => "turn",
AngleDimension::Grad(_) => "grad",
}
}
}
/// A specified Angle value, which is just the angle dimension, plus whether it
/// was specified as `calc()` or not.
#[cfg_attr(feature = "servo", derive(Deserialize, Serialize))]
#[derive(Clone, Copy, Debug, MallocSizeOf, PartialEq, ToShmem)]
pub struct Angle {
value: AngleDimension,
was_calc: bool,
}
impl Zero for Angle {
fn zero() -> Self {
Self {
value: Zero::zero(),
was_calc: false,
}
}
fn is_zero(&self) -> bool {
self.value.is_zero()
}
}
impl ToCss for Angle {
fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
where
W: Write,
{
crate::values::serialize_specified_dimension(
self.value.unitless_value(),
self.value.unit(),
self.was_calc,
dest,
)
}
}
impl ToComputedValue for Angle {
type ComputedValue = ComputedAngle;
#[inline]
fn to_computed_value(&self, _context: &Context) -> Self::ComputedValue {
let degrees = self.degrees();
// NaN and +-infinity should degenerate to 0:
https://github.com/w3c/csswg-drafts/issues/6105
ComputedAngle::from_degrees(if degrees.is_finite() { degrees } else { 0.0 })
}
#[inline]
fn from_computed_value(computed: &Self::ComputedValue) -> Self {
Angle {
value: AngleDimension::Deg(computed.degrees()),
was_calc: false,
}
}
}
impl Angle {
/// Creates an angle with the given value in degrees.
#[inline]
pub fn from_degrees(value: CSSFloat, was_calc: bool) -> Self {
Angle {
value: AngleDimension::Deg(value),
was_calc,
}
}
/// Creates an angle with the given value in radians.
#[inline]
pub fn from_radians(value: CSSFloat) -> Self {
Angle {
value: AngleDimension::Rad(value),
was_calc: false,
}
}
/// Return `0deg`.
pub fn zero() -> Self {
Self::from_degrees(0.0, false)
}
/// Returns the value of the angle in degrees, mostly for `calc()`.
#[inline]
pub fn degrees(&self) -> CSSFloat {
self.value.degrees()
}
/// Returns the value of the angle in radians.
#[inline]
pub fn radians(&self) -> CSSFloat {
const RAD_PER_DEG: f32 = PI / 180.0;
self.value.degrees() * RAD_PER_DEG
}
/// Whether this specified angle came from a `calc()` expression.
#[inline]
pub fn was_calc(&self) -> bool {
self.was_calc
}
/// Returns an `Angle` parsed from a `calc()` expression.
pub fn from_calc(degrees: CSSFloat) -> Self {
Angle {
value: AngleDimension::Deg(degrees),
was_calc: true,
}
}
/// Returns the unit of the angle.
#[inline]
pub fn unit(&self) -> &'static str {
self.value.unit()
}
}
/// Whether to allow parsing an unitless zero as a valid angle.
///
/// This should always be `No`, except for exceptions like:
///
///
https://github.com/w3c/fxtf-drafts/issues/228
///
/// See also:
https://github.com/w3c/csswg-drafts/issues/1162.
#[allow(missing_docs)]
pub enum AllowUnitlessZeroAngle {
Yes,
No,
}
impl Parse for Angle {
/// Parses an angle according to CSS-VALUES § 6.1.
fn parse<'i, 't>(
context: &ParserContext,
input: &mut Parser<'i, 't>,
) -> Result<Self, ParseError<'i>> {
Self::parse_internal(context, input, AllowUnitlessZeroAngle::No)
}
}
impl Angle {
/// Parse an `<angle>` value given a value and an unit.
pub fn parse_dimension(value: CSSFloat, unit: &str, was_calc: bool) -> Result<Angle, ()> {
let value = match_ignore_ascii_case! { unit,
"deg" => AngleDimension::Deg(value),
"grad" => AngleDimension::Grad(value),
"turn" => AngleDimension::Turn(value),
"rad" => AngleDimension::Rad(value),
_ => return Err(())
};
Ok(Self { value, was_calc })
}
/// Parse an `<angle>` allowing unitless zero to represent a zero angle.
///
/// See the comment in `AllowUnitlessZeroAngle` for why.
#[inline]
pub fn parse_with_unitless<'i, 't>(
context: &ParserContext,
input: &mut Parser<'i, 't>,
) -> Result<Self, ParseError<'i>> {
Self::parse_internal(context, input, AllowUnitlessZeroAngle::Yes)
}
pub(super) fn parse_internal<'i, 't>(
context: &ParserContext,
input: &mut Parser<'i, 't>,
allow_unitless_zero: AllowUnitlessZeroAngle,
) -> Result<Self, ParseError<'i>> {
let location = input.current_source_location();
let t = input.next()?;
let allow_unitless_zero = matches!(allow_unitless_zero, AllowUnitlessZeroAngle::Yes)
;
match *t {
Token::Dimension {
value, ref unit, ..
} => {
match Angle::parse_dimension(value, unit, /* from_calc = */ false) {
Ok(angle) => Ok(angle),
Err(()) => {
let t = t.clone();
Err(input.new_unexpected_token_error(t))
},
}
},
Token::Function(ref name) => {
let function = CalcNode::math_function(context, name, location)?;
CalcNode::parse_angle(context, input, function)
},
Token::Number { value, .. } if value == 0. && allow_unitless_zero => Ok(Angle::zero()),
ref t => {
let t = t.clone();
Err(input.new_unexpected_token_error(t))
},
}
}
}
impl SpecifiedValueInfo for Angle {}
