1 files changed, 196 insertions, 0 deletions
diff --git a/servo/components/style/values/generics/color.rs b/servo/components/style/values/generics/color.rs
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+++ b/servo/components/style/values/generics/color.rs
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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/. */
+
+//! Generic types for color properties.
+
+use crate::color::mix::ColorInterpolationMethod;
+use crate::color::AbsoluteColor;
+use crate::values::specified::percentage::ToPercentage;
+use std::fmt::{self, Write};
+use style_traits::{CssWriter, ToCss};
+
+/// This struct represents a combined color from a numeric color and
+/// the current foreground color (currentcolor keyword).
+#[derive(Clone, Debug, MallocSizeOf, PartialEq, ToAnimatedValue, ToShmem)]
+#[repr(C)]
+pub enum GenericColor<Percentage> {
+    /// The actual numeric color.
+    Absolute(AbsoluteColor),
+    /// The `CurrentColor` keyword.
+    CurrentColor,
+    /// The color-mix() function.
+    ColorMix(Box<GenericColorMix<Self, Percentage>>),
+}
+
+/// A restricted version of the css `color-mix()` function, which only supports
+/// percentages.
+///
+/// https://drafts.csswg.org/css-color-5/#color-mix
+#[derive(
+    Clone,
+    Debug,
+    MallocSizeOf,
+    PartialEq,
+    ToAnimatedValue,
+    ToComputedValue,
+    ToResolvedValue,
+    ToShmem,
+)]
+#[allow(missing_docs)]
+#[repr(C)]
+pub struct GenericColorMix<Color, Percentage> {
+    pub interpolation: ColorInterpolationMethod,
+    pub left: Color,
+    pub left_percentage: Percentage,
+    pub right: Color,
+    pub right_percentage: Percentage,
+    pub normalize_weights: bool,
+}
+
+pub use self::GenericColorMix as ColorMix;
+
+impl<Color: ToCss, Percentage: ToCss + ToPercentage> ToCss for ColorMix<Color, Percentage> {
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
+    {
+        fn can_omit<Percentage: ToPercentage>(
+            percent: &Percentage,
+            other: &Percentage,
+            is_left: bool,
+        ) -> bool {
+            if percent.is_calc() {
+                return false;
+            }
+            if percent.to_percentage() == 0.5 {
+                return other.to_percentage() == 0.5;
+            }
+            if is_left {
+                return false;
+            }
+            (1.0 - percent.to_percentage() - other.to_percentage()).abs() <= f32::EPSILON
+        }
+
+        dest.write_str("color-mix(")?;
+        self.interpolation.to_css(dest)?;
+        dest.write_str(", ")?;
+        self.left.to_css(dest)?;
+        if !can_omit(&self.left_percentage, &self.right_percentage, true) {
+            dest.write_char(' ')?;
+            self.left_percentage.to_css(dest)?;
+        }
+        dest.write_str(", ")?;
+        self.right.to_css(dest)?;
+        if !can_omit(&self.right_percentage, &self.left_percentage, false) {
+            dest.write_char(' ')?;
+            self.right_percentage.to_css(dest)?;
+        }
+        dest.write_char(')')
+    }
+}
+
+impl<Percentage> ColorMix<GenericColor<Percentage>, Percentage> {
+    /// Mix the colors so that we get a single color. If any of the 2 colors are
+    /// not mixable (perhaps not absolute?), then return None.
+    pub fn mix_to_absolute(&self) -> Option<AbsoluteColor>
+    where
+        Percentage: ToPercentage,
+    {
+        let left = self.left.as_absolute()?;
+        let right = self.right.as_absolute()?;
+
+        Some(crate::color::mix::mix(
+            self.interpolation,
+            &left,
+            self.left_percentage.to_percentage(),
+            &right,
+            self.right_percentage.to_percentage(),
+            self.normalize_weights,
+        ))
+    }
+}
+
+pub use self::GenericColor as Color;
+
+impl<Percentage> Color<Percentage> {
+    /// If this color is absolute return it's value, otherwise return None.
+    pub fn as_absolute(&self) -> Option<&AbsoluteColor> {
+        match *self {
+            Self::Absolute(ref absolute) => Some(absolute),
+            _ => None,
+        }
+    }
+
+    /// Returns a color value representing currentcolor.
+    pub fn currentcolor() -> Self {
+        Self::CurrentColor
+    }
+
+    /// Whether it is a currentcolor value (no numeric color component).
+    pub fn is_currentcolor(&self) -> bool {
+        matches!(*self, Self::CurrentColor)
+    }
+
+    /// Whether this color is an absolute color.
+    pub fn is_absolute(&self) -> bool {
+        matches!(*self, Self::Absolute(..))
+    }
+}
+
+/// Either `<color>` or `auto`.
+#[derive(
+    Animate,
+    Clone,
+    ComputeSquaredDistance,
+    Copy,
+    Debug,
+    MallocSizeOf,
+    PartialEq,
+    Parse,
+    SpecifiedValueInfo,
+    ToAnimatedValue,
+    ToAnimatedZero,
+    ToComputedValue,
+    ToResolvedValue,
+    ToCss,
+    ToShmem,
+)]
+#[repr(C, u8)]
+pub enum GenericColorOrAuto<C> {
+    /// A `<color>`.
+    Color(C),
+    /// `auto`
+    Auto,
+}
+
+pub use self::GenericColorOrAuto as ColorOrAuto;
+
+/// Caret color is effectively a ColorOrAuto, but resolves `auto` to
+/// currentColor.
+#[derive(
+    Animate,
+    Clone,
+    ComputeSquaredDistance,
+    Copy,
+    Debug,
+    MallocSizeOf,
+    PartialEq,
+    SpecifiedValueInfo,
+    ToAnimatedValue,
+    ToAnimatedZero,
+    ToComputedValue,
+    ToCss,
+    ToShmem,
+)]
+#[repr(transparent)]
+pub struct GenericCaretColor<C>(pub GenericColorOrAuto<C>);
+
+impl<C> GenericCaretColor<C> {
+    /// Returns the `auto` value.
+    pub fn auto() -> Self {
+        GenericCaretColor(GenericColorOrAuto::Auto)
+    }
+}
+
+pub use self::GenericCaretColor as CaretColor;