/* 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/. */
//! Parse/serialize and resolve a single color component.
use std::fmt::Write;
use super::{
parsing::{rcs_enabled, ChannelKeyword},
AbsoluteColor,
};
use crate::{
parser::ParserContext,
values::{
animated::ToAnimatedValue,
generics::calc::{CalcUnits, GenericCalcNode},
specified::calc::{AllowParse, Leaf},
},
};
use cssparser::{color::OPAQUE, Parser, Token};
use style_traits::{ParseError, ToCss};
/// A single color component.
#[derive(Clone, Debug, MallocSizeOf, PartialEq, ToShmem)]
#[repr(u8)]
pub enum ColorComponent<ValueType> {
/// The "none" keyword.
None,
/// A absolute value.
Value(ValueType),
/// A channel keyword, e.g. `r`, `l`, `alpha`, etc.
ChannelKeyword(ChannelKeyword),
/// A calc() value.
Calc(Box<GenericCalcNode<Leaf>>),
/// Used when alpha components are not specified.
AlphaOmitted,
}
impl<ValueType> ColorComponent<ValueType> {
/// Return true if the component is "none".
#[inline]
pub fn is_none(&self) -> bool {
matches!(self, Self::None)
}
}
/// An utility trait that allows the construction of [ColorComponent]
/// `ValueType`'s after parsing a color component.
pub trait ColorComponentType: Sized + Clone {
// TODO(tlouw): This function should be named according to the rules in the spec
// stating that all the values coming from color components are
// numbers and that each has their own rules dependeing on types.
/// Construct a new component from a single value.
fn from_value(value: f32) -> Self;
/// Return the [CalcUnits] flags that the impl can handle.
fn units() -> CalcUnits;
/// Try to create a new component from the given token.
fn try_from_token(token: &Token) -> Result<Self, ()>;
/// Try to create a new component from the given [CalcNodeLeaf] that was
/// resolved from a [CalcNode].
fn try_from_leaf(leaf: &Leaf) -> Result<Self, ()>;
}
impl<ValueType: ColorComponentType> ColorComponent<ValueType> {
/// Parse a single [ColorComponent].
pub fn parse<'i, 't>(
context: &ParserContext,
input: &mut Parser<'i, 't>,
allow_none: bool,
) -> Result<Self, ParseError<'i>> {
let location = input.current_source_location();
match *input.next()? {
Token::Ident(ref value) if allow_none && value.eq_ignore_ascii_case("none") => {
Ok(ColorComponent::None)
},
ref t @ Token::Ident(ref ident) => {
let Ok(channel_keyword) = ChannelKeyword::from_ident(ident) else {
return Err(location.new_unexpected_token_error(t.clone()));
};
Ok(ColorComponent::ChannelKeyword(channel_keyword))
},
Token::Function(ref name) => {
let function = GenericCalcNode::math_function(context, name, location)?;
let allow = AllowParse::new(if rcs_enabled() {
ValueType::units() | CalcUnits::COLOR_COMPONENT
} else {
ValueType::units()
});
let node = GenericCalcNode::parse(context, input, function, allow)?;
debug_assert!(!node.has_anchor_function, "Anchor function used for color?");
let mut node = node.node;
// TODO(tlouw): We only have to simplify the node when we have to store it, but we
// only know if we have to store it much later when the whole color
// can't be resolved to absolute at which point the calc nodes are
// burried deep in a [ColorFunction] struct.
node.simplify_and_sort();
Ok(Self::Calc(Box::new(node)))
},
ref t => ValueType::try_from_token(t)
.map(Self::Value)
.map_err(|_| location.new_unexpected_token_error(t.clone())),
}
}
/// Resolve a [ColorComponent] into a float. None is "none".
pub fn resolve(&self, origin_color: Option<&AbsoluteColor>) -> Result<Option<ValueType>, ()> {
Ok(match self {
ColorComponent::None => None,
ColorComponent::Value(value) => Some(value.clone()),
ColorComponent::ChannelKeyword(channel_keyword) => match origin_color {
Some(origin_color) => {
let value = origin_color.get_component_by_channel_keyword(*channel_keyword)?;
Some(ValueType::from_value(value.unwrap_or(0.0)))
},
None => return Err(()),
},
ColorComponent::Calc(node) => {
let Ok(resolved_leaf) = node.resolve_map(
|leaf| {
Ok(match leaf {
Leaf::ColorComponent(channel_keyword) => match origin_color {
Some(origin_color) => {
let value = origin_color
.get_component_by_channel_keyword(*channel_keyword)?;
Leaf::Number(value.unwrap_or(0.0))
},
None => return Err(()),
},
l => l.clone(),
})
},
|_| Err(()),
) else {
return Err(());
};
Some(ValueType::try_from_leaf(&resolved_leaf)?)
},
ColorComponent::AlphaOmitted => {
if let Some(origin_color) = origin_color {
// <
https://drafts.csswg.org/css-color-5/#rcs-intro>
// If the alpha value of the relative color is omitted, it defaults to that of
// the origin color (rather than defaulting to 100%, as it does in the absolute
// syntax).
origin_color.alpha().map(ValueType::from_value)
} else {
Some(ValueType::from_value(OPAQUE))
}
},
})
}
}
impl<ValueType: ToCss> ToCss for ColorComponent<ValueType> {
fn to_css<W>(&self, dest: &mut style_traits::CssWriter<W>) -> std::fmt::Result
where
W: Write,
{
match self {
ColorComponent::None => dest.write_str("none")?,
ColorComponent::Value(value) => value.to_css(dest)?,
ColorComponent::ChannelKeyword(channel_keyword) => channel_keyword.to_css(dest)?,
ColorComponent::Calc(node) => {
// When we only have a channel keyword in a leaf node, we should serialize it with
// calc(..), except when one of the rgb color space functions are used, e.g.
// rgb(..), hsl(..) or hwb(..) for historical reasons.
// <
https://github.com/web-platform-tests/wpt/issues/47921>
node.to_css(dest)?;
},
ColorComponent::AlphaOmitted => {
debug_assert!(false, "can't serialize an omitted alpha component");
},
}
Ok(())
}
}
impl<ValueType> ToAnimatedValue for ColorComponent<ValueType> {
type AnimatedValue = Self;
fn to_animated_value(self, _context: &crate::values::animated::Context) -> Self::AnimatedValue {
self
}
fn from_animated_value(animated: Self::AnimatedValue) -> Self {
animated
}
}
