Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 879 insertions, 0 deletions

diff --git a/servo/components/style/values/generics/transform.rs b/servo/components/style/values/generics/transform.rs
new file mode 100644
index 0000000000..3a65c460a7
--- /dev/null
+++ b/servo/components/style/values/generics/transform.rs
@@ -0,0 +1,879 @@
+/* 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 CSS values that are related to transformations.
+
+use crate::values::computed::length::Length as ComputedLength;
+use crate::values::computed::length::LengthPercentage as ComputedLengthPercentage;
+use crate::values::specified::angle::Angle as SpecifiedAngle;
+use crate::values::specified::length::Length as SpecifiedLength;
+use crate::values::specified::length::LengthPercentage as SpecifiedLengthPercentage;
+use crate::values::{computed, CSSFloat};
+use crate::{Zero, ZeroNoPercent};
+use euclid;
+use euclid::default::{Rect, Transform3D};
+use std::fmt::{self, Write};
+use style_traits::{CssWriter, ToCss};
+
+/// A generic 2D transformation matrix.
+#[allow(missing_docs)]
+#[derive(
+    Clone,
+    Copy,
+    Debug,
+    Deserialize,
+    MallocSizeOf,
+    PartialEq,
+    Serialize,
+    SpecifiedValueInfo,
+    ToComputedValue,
+    ToCss,
+    ToResolvedValue,
+    ToShmem,
+)]
+#[css(comma, function = "matrix")]
+#[repr(C)]
+pub struct GenericMatrix<T> {
+    pub a: T,
+    pub b: T,
+    pub c: T,
+    pub d: T,
+    pub e: T,
+    pub f: T,
+}
+
+pub use self::GenericMatrix as Matrix;
+
+#[allow(missing_docs)]
+#[cfg_attr(rustfmt, rustfmt_skip)]
+#[derive(
+    Clone,
+    Copy,
+    Debug,
+    Deserialize,
+    MallocSizeOf,
+    PartialEq,
+    Serialize,
+    SpecifiedValueInfo,
+    ToComputedValue,
+    ToCss,
+    ToResolvedValue,
+    ToShmem,
+)]
+#[css(comma, function = "matrix3d")]
+#[repr(C)]
+pub struct GenericMatrix3D<T> {
+    pub m11: T, pub m12: T, pub m13: T, pub m14: T,
+    pub m21: T, pub m22: T, pub m23: T, pub m24: T,
+    pub m31: T, pub m32: T, pub m33: T, pub m34: T,
+    pub m41: T, pub m42: T, pub m43: T, pub m44: T,
+}
+
+pub use self::GenericMatrix3D as Matrix3D;
+
+#[cfg_attr(rustfmt, rustfmt_skip)]
+impl<T: Into<f64>> From<Matrix<T>> for Transform3D<f64> {
+    #[inline]
+    fn from(m: Matrix<T>) -> Self {
+        Transform3D::new(
+            m.a.into(), m.b.into(), 0.0, 0.0,
+            m.c.into(), m.d.into(), 0.0, 0.0,
+            0.0,        0.0,        1.0, 0.0,
+            m.e.into(), m.f.into(), 0.0, 1.0,
+        )
+    }
+}
+
+#[cfg_attr(rustfmt, rustfmt_skip)]
+impl<T: Into<f64>> From<Matrix3D<T>> for Transform3D<f64> {
+    #[inline]
+    fn from(m: Matrix3D<T>) -> Self {
+        Transform3D::new(
+            m.m11.into(), m.m12.into(), m.m13.into(), m.m14.into(),
+            m.m21.into(), m.m22.into(), m.m23.into(), m.m24.into(),
+            m.m31.into(), m.m32.into(), m.m33.into(), m.m34.into(),
+            m.m41.into(), m.m42.into(), m.m43.into(), m.m44.into(),
+        )
+    }
+}
+
+/// A generic transform origin.
+#[derive(
+    Animate,
+    Clone,
+    ComputeSquaredDistance,
+    Copy,
+    Debug,
+    MallocSizeOf,
+    PartialEq,
+    SpecifiedValueInfo,
+    ToAnimatedZero,
+    ToComputedValue,
+    ToCss,
+    ToResolvedValue,
+    ToShmem,
+)]
+#[repr(C)]
+pub struct GenericTransformOrigin<H, V, Depth> {
+    /// The horizontal origin.
+    pub horizontal: H,
+    /// The vertical origin.
+    pub vertical: V,
+    /// The depth.
+    pub depth: Depth,
+}
+
+pub use self::GenericTransformOrigin as TransformOrigin;
+
+impl<H, V, D> TransformOrigin<H, V, D> {
+    /// Returns a new transform origin.
+    pub fn new(horizontal: H, vertical: V, depth: D) -> Self {
+        Self {
+            horizontal,
+            vertical,
+            depth,
+        }
+    }
+}
+
+fn is_same<N: PartialEq>(x: &N, y: &N) -> bool {
+    x == y
+}
+
+/// A value for the `perspective()` transform function, which is either a
+/// non-negative `<length>` or `none`.
+#[derive(
+    Clone,
+    Debug,
+    Deserialize,
+    MallocSizeOf,
+    PartialEq,
+    Serialize,
+    SpecifiedValueInfo,
+    ToComputedValue,
+    ToCss,
+    ToResolvedValue,
+    ToShmem,
+)]
+#[repr(C, u8)]
+pub enum GenericPerspectiveFunction<L> {
+    /// `none`
+    None,
+    /// A `<length>`.
+    Length(L),
+}
+
+impl<L> GenericPerspectiveFunction<L> {
+    /// Returns `f32::INFINITY` or the result of a function on the length value.
+    pub fn infinity_or(&self, f: impl FnOnce(&L) -> f32) -> f32 {
+        match *self {
+            Self::None => f32::INFINITY,
+            Self::Length(ref l) => f(l),
+        }
+    }
+}
+
+pub use self::GenericPerspectiveFunction as PerspectiveFunction;
+
+#[derive(
+    Clone,
+    Debug,
+    Deserialize,
+    MallocSizeOf,
+    PartialEq,
+    Serialize,
+    SpecifiedValueInfo,
+    ToComputedValue,
+    ToCss,
+    ToResolvedValue,
+    ToShmem,
+)]
+#[repr(C, u8)]
+/// A single operation in the list of a `transform` value
+pub enum GenericTransformOperation<Angle, Number, Length, Integer, LengthPercentage>
+where
+    Angle: Zero,
+    LengthPercentage: Zero + ZeroNoPercent,
+    Number: PartialEq,
+{
+    /// Represents a 2D 2x3 matrix.
+    Matrix(GenericMatrix<Number>),
+    /// Represents a 3D 4x4 matrix.
+    Matrix3D(GenericMatrix3D<Number>),
+    /// A 2D skew.
+    ///
+    /// If the second angle is not provided it is assumed zero.
+    ///
+    /// Syntax can be skew(angle) or skew(angle, angle)
+    #[css(comma, function)]
+    Skew(Angle, #[css(skip_if = "Zero::is_zero")] Angle),
+    /// skewX(angle)
+    #[css(function = "skewX")]
+    SkewX(Angle),
+    /// skewY(angle)
+    #[css(function = "skewY")]
+    SkewY(Angle),
+    /// translate(x, y) or translate(x)
+    #[css(comma, function)]
+    Translate(
+        LengthPercentage,
+        #[css(skip_if = "ZeroNoPercent::is_zero_no_percent")] LengthPercentage,
+    ),
+    /// translateX(x)
+    #[css(function = "translateX")]
+    TranslateX(LengthPercentage),
+    /// translateY(y)
+    #[css(function = "translateY")]
+    TranslateY(LengthPercentage),
+    /// translateZ(z)
+    #[css(function = "translateZ")]
+    TranslateZ(Length),
+    /// translate3d(x, y, z)
+    #[css(comma, function = "translate3d")]
+    Translate3D(LengthPercentage, LengthPercentage, Length),
+    /// A 2D scaling factor.
+    ///
+    /// Syntax can be scale(factor) or scale(factor, factor)
+    #[css(comma, function)]
+    Scale(Number, #[css(contextual_skip_if = "is_same")] Number),
+    /// scaleX(factor)
+    #[css(function = "scaleX")]
+    ScaleX(Number),
+    /// scaleY(factor)
+    #[css(function = "scaleY")]
+    ScaleY(Number),
+    /// scaleZ(factor)
+    #[css(function = "scaleZ")]
+    ScaleZ(Number),
+    /// scale3D(factorX, factorY, factorZ)
+    #[css(comma, function = "scale3d")]
+    Scale3D(Number, Number, Number),
+    /// Describes a 2D Rotation.
+    ///
+    /// In a 3D scene `rotate(angle)` is equivalent to `rotateZ(angle)`.
+    #[css(function)]
+    Rotate(Angle),
+    /// Rotation in 3D space around the x-axis.
+    #[css(function = "rotateX")]
+    RotateX(Angle),
+    /// Rotation in 3D space around the y-axis.
+    #[css(function = "rotateY")]
+    RotateY(Angle),
+    /// Rotation in 3D space around the z-axis.
+    #[css(function = "rotateZ")]
+    RotateZ(Angle),
+    /// Rotation in 3D space.
+    ///
+    /// Generalization of rotateX, rotateY and rotateZ.
+    #[css(comma, function = "rotate3d")]
+    Rotate3D(Number, Number, Number, Angle),
+    /// Specifies a perspective projection matrix.
+    ///
+    /// Part of CSS Transform Module Level 2 and defined at
+    /// [§ 13.1. 3D Transform Function](https://drafts.csswg.org/css-transforms-2/#funcdef-perspective).
+    ///
+    /// The value must be greater than or equal to zero.
+    #[css(function)]
+    Perspective(GenericPerspectiveFunction<Length>),
+    /// A intermediate type for interpolation of mismatched transform lists.
+    #[allow(missing_docs)]
+    #[css(comma, function = "interpolatematrix")]
+    InterpolateMatrix {
+        from_list: GenericTransform<
+            GenericTransformOperation<Angle, Number, Length, Integer, LengthPercentage>,
+        >,
+        to_list: GenericTransform<
+            GenericTransformOperation<Angle, Number, Length, Integer, LengthPercentage>,
+        >,
+        progress: computed::Percentage,
+    },
+    /// A intermediate type for accumulation of mismatched transform lists.
+    #[allow(missing_docs)]
+    #[css(comma, function = "accumulatematrix")]
+    AccumulateMatrix {
+        from_list: GenericTransform<
+            GenericTransformOperation<Angle, Number, Length, Integer, LengthPercentage>,
+        >,
+        to_list: GenericTransform<
+            GenericTransformOperation<Angle, Number, Length, Integer, LengthPercentage>,
+        >,
+        count: Integer,
+    },
+}
+
+pub use self::GenericTransformOperation as TransformOperation;
+
+#[derive(
+    Clone,
+    Debug,
+    Deserialize,
+    MallocSizeOf,
+    PartialEq,
+    Serialize,
+    SpecifiedValueInfo,
+    ToComputedValue,
+    ToCss,
+    ToResolvedValue,
+    ToShmem,
+)]
+#[repr(C)]
+/// A value of the `transform` property
+pub struct GenericTransform<T>(#[css(if_empty = "none", iterable)] pub crate::OwnedSlice<T>);
+
+pub use self::GenericTransform as Transform;
+
+impl<Angle, Number, Length, Integer, LengthPercentage>
+    TransformOperation<Angle, Number, Length, Integer, LengthPercentage>
+where
+    Angle: Zero,
+    LengthPercentage: Zero + ZeroNoPercent,
+    Number: PartialEq,
+{
+    /// Check if it is any rotate function.
+    pub fn is_rotate(&self) -> bool {
+        use self::TransformOperation::*;
+        matches!(
+            *self,
+            Rotate(..) | Rotate3D(..) | RotateX(..) | RotateY(..) | RotateZ(..)
+        )
+    }
+
+    /// Check if it is any translate function
+    pub fn is_translate(&self) -> bool {
+        use self::TransformOperation::*;
+        match *self {
+            Translate(..) | Translate3D(..) | TranslateX(..) | TranslateY(..) | TranslateZ(..) => {
+                true
+            },
+            _ => false,
+        }
+    }
+
+    /// Check if it is any scale function
+    pub fn is_scale(&self) -> bool {
+        use self::TransformOperation::*;
+        match *self {
+            Scale(..) | Scale3D(..) | ScaleX(..) | ScaleY(..) | ScaleZ(..) => true,
+            _ => false,
+        }
+    }
+}
+
+/// Convert a length type into the absolute lengths.
+pub trait ToAbsoluteLength {
+    /// Returns the absolute length as pixel value.
+    fn to_pixel_length(&self, containing_len: Option<ComputedLength>) -> Result<CSSFloat, ()>;
+}
+
+impl ToAbsoluteLength for SpecifiedLength {
+    // This returns Err(()) if there is any relative length or percentage. We use this when
+    // parsing a transform list of DOMMatrix because we want to return a DOM Exception
+    // if there is relative length.
+    #[inline]
+    fn to_pixel_length(&self, _containing_len: Option<ComputedLength>) -> Result<CSSFloat, ()> {
+        match *self {
+            SpecifiedLength::NoCalc(len) => len.to_computed_pixel_length_without_context(),
+            SpecifiedLength::Calc(ref calc) => calc.to_computed_pixel_length_without_context(),
+        }
+    }
+}
+
+impl ToAbsoluteLength for SpecifiedLengthPercentage {
+    // This returns Err(()) if there is any relative length or percentage. We use this when
+    // parsing a transform list of DOMMatrix because we want to return a DOM Exception
+    // if there is relative length.
+    #[inline]
+    fn to_pixel_length(&self, _containing_len: Option<ComputedLength>) -> Result<CSSFloat, ()> {
+        use self::SpecifiedLengthPercentage::*;
+        match *self {
+            Length(len) => len.to_computed_pixel_length_without_context(),
+            Calc(ref calc) => calc.to_computed_pixel_length_without_context(),
+            Percentage(..) => Err(()),
+        }
+    }
+}
+
+impl ToAbsoluteLength for ComputedLength {
+    #[inline]
+    fn to_pixel_length(&self, _containing_len: Option<ComputedLength>) -> Result<CSSFloat, ()> {
+        Ok(self.px())
+    }
+}
+
+impl ToAbsoluteLength for ComputedLengthPercentage {
+    #[inline]
+    fn to_pixel_length(&self, containing_len: Option<ComputedLength>) -> Result<CSSFloat, ()> {
+        Ok(self
+            .maybe_percentage_relative_to(containing_len)
+            .ok_or(())?
+            .px())
+    }
+}
+
+/// Support the conversion to a 3d matrix.
+pub trait ToMatrix {
+    /// Check if it is a 3d transform function.
+    fn is_3d(&self) -> bool;
+
+    /// Return the equivalent 3d matrix.
+    fn to_3d_matrix(
+        &self,
+        reference_box: Option<&Rect<ComputedLength>>,
+    ) -> Result<Transform3D<f64>, ()>;
+}
+
+/// A little helper to deal with both specified and computed angles.
+pub trait ToRadians {
+    /// Return the radians value as a 64-bit floating point value.
+    fn radians64(&self) -> f64;
+}
+
+impl ToRadians for computed::angle::Angle {
+    #[inline]
+    fn radians64(&self) -> f64 {
+        computed::angle::Angle::radians64(self)
+    }
+}
+
+impl ToRadians for SpecifiedAngle {
+    #[inline]
+    fn radians64(&self) -> f64 {
+        computed::angle::Angle::from_degrees(self.degrees()).radians64()
+    }
+}
+
+impl<Angle, Number, Length, Integer, LoP> ToMatrix
+    for TransformOperation<Angle, Number, Length, Integer, LoP>
+where
+    Angle: Zero + ToRadians + Copy,
+    Number: PartialEq + Copy + Into<f32> + Into<f64>,
+    Length: ToAbsoluteLength,
+    LoP: Zero + ToAbsoluteLength + ZeroNoPercent,
+{
+    #[inline]
+    fn is_3d(&self) -> bool {
+        use self::TransformOperation::*;
+        match *self {
+            Translate3D(..) | TranslateZ(..) | Rotate3D(..) | RotateX(..) | RotateY(..) |
+            RotateZ(..) | Scale3D(..) | ScaleZ(..) | Perspective(..) | Matrix3D(..) => true,
+            _ => false,
+        }
+    }
+
+    /// If |reference_box| is None, we will drop the percent part from translate because
+    /// we cannot resolve it without the layout info, for computed TransformOperation.
+    /// However, for specified TransformOperation, we will return Err(()) if there is any relative
+    /// lengths because the only caller, DOMMatrix, doesn't accept relative lengths.
+    #[inline]
+    fn to_3d_matrix(
+        &self,
+        reference_box: Option<&Rect<ComputedLength>>,
+    ) -> Result<Transform3D<f64>, ()> {
+        use self::TransformOperation::*;
+
+        let reference_width = reference_box.map(|v| v.size.width);
+        let reference_height = reference_box.map(|v| v.size.height);
+        let matrix = match *self {
+            Rotate3D(ax, ay, az, theta) => {
+                let theta = theta.radians64();
+                let (ax, ay, az, theta) =
+                    get_normalized_vector_and_angle(ax.into(), ay.into(), az.into(), theta);
+                Transform3D::rotation(
+                    ax as f64,
+                    ay as f64,
+                    az as f64,
+                    euclid::Angle::radians(theta),
+                )
+            },
+            RotateX(theta) => {
+                let theta = euclid::Angle::radians(theta.radians64());
+                Transform3D::rotation(1., 0., 0., theta)
+            },
+            RotateY(theta) => {
+                let theta = euclid::Angle::radians(theta.radians64());
+                Transform3D::rotation(0., 1., 0., theta)
+            },
+            RotateZ(theta) | Rotate(theta) => {
+                let theta = euclid::Angle::radians(theta.radians64());
+                Transform3D::rotation(0., 0., 1., theta)
+            },
+            Perspective(ref p) => {
+                let px = match p {
+                    PerspectiveFunction::None => f32::INFINITY,
+                    PerspectiveFunction::Length(ref p) => p.to_pixel_length(None)?,
+                };
+                create_perspective_matrix(px).cast()
+            },
+            Scale3D(sx, sy, sz) => Transform3D::scale(sx.into(), sy.into(), sz.into()),
+            Scale(sx, sy) => Transform3D::scale(sx.into(), sy.into(), 1.),
+            ScaleX(s) => Transform3D::scale(s.into(), 1., 1.),
+            ScaleY(s) => Transform3D::scale(1., s.into(), 1.),
+            ScaleZ(s) => Transform3D::scale(1., 1., s.into()),
+            Translate3D(ref tx, ref ty, ref tz) => {
+                let tx = tx.to_pixel_length(reference_width)? as f64;
+                let ty = ty.to_pixel_length(reference_height)? as f64;
+                Transform3D::translation(tx, ty, tz.to_pixel_length(None)? as f64)
+            },
+            Translate(ref tx, ref ty) => {
+                let tx = tx.to_pixel_length(reference_width)? as f64;
+                let ty = ty.to_pixel_length(reference_height)? as f64;
+                Transform3D::translation(tx, ty, 0.)
+            },
+            TranslateX(ref t) => {
+                let t = t.to_pixel_length(reference_width)? as f64;
+                Transform3D::translation(t, 0., 0.)
+            },
+            TranslateY(ref t) => {
+                let t = t.to_pixel_length(reference_height)? as f64;
+                Transform3D::translation(0., t, 0.)
+            },
+            TranslateZ(ref z) => Transform3D::translation(0., 0., z.to_pixel_length(None)? as f64),
+            Skew(theta_x, theta_y) => Transform3D::skew(
+                euclid::Angle::radians(theta_x.radians64()),
+                euclid::Angle::radians(theta_y.radians64()),
+            ),
+            SkewX(theta) => Transform3D::skew(
+                euclid::Angle::radians(theta.radians64()),
+                euclid::Angle::radians(0.),
+            ),
+            SkewY(theta) => Transform3D::skew(
+                euclid::Angle::radians(0.),
+                euclid::Angle::radians(theta.radians64()),
+            ),
+            Matrix3D(m) => m.into(),
+            Matrix(m) => m.into(),
+            InterpolateMatrix { .. } | AccumulateMatrix { .. } => {
+                // TODO: Convert InterpolateMatrix/AccumulateMatrix into a valid Transform3D by
+                // the reference box and do interpolation on these two Transform3D matrices.
+                // Both Gecko and Servo don't support this for computing distance, and Servo
+                // doesn't support animations on InterpolateMatrix/AccumulateMatrix, so
+                // return an identity matrix.
+                // Note: DOMMatrix doesn't go into this arm.
+                Transform3D::identity()
+            },
+        };
+        Ok(matrix)
+    }
+}
+
+impl<T> Transform<T> {
+    /// `none`
+    pub fn none() -> Self {
+        Transform(Default::default())
+    }
+}
+
+impl<T: ToMatrix> Transform<T> {
+    /// Return the equivalent 3d matrix of this transform list.
+    ///
+    /// We return a pair: the first one is the transform matrix, and the second one
+    /// indicates if there is any 3d transform function in this transform list.
+    #[cfg_attr(rustfmt, rustfmt_skip)]
+    pub fn to_transform_3d_matrix(
+        &self,
+        reference_box: Option<&Rect<ComputedLength>>
+    ) -> Result<(Transform3D<CSSFloat>, bool), ()> {
+        Self::components_to_transform_3d_matrix(&self.0, reference_box)
+    }
+
+    /// Converts a series of components to a 3d matrix.
+    #[cfg_attr(rustfmt, rustfmt_skip)]
+    pub fn components_to_transform_3d_matrix(
+        ops: &[T],
+        reference_box: Option<&Rect<ComputedLength>>,
+    ) -> Result<(Transform3D<CSSFloat>, bool), ()> {
+        let cast_3d_transform = |m: Transform3D<f64>| -> Transform3D<CSSFloat> {
+            use std::{f32, f64};
+            let cast = |v: f64| v.min(f32::MAX as f64).max(f32::MIN as f64) as f32;
+            Transform3D::new(
+                cast(m.m11), cast(m.m12), cast(m.m13), cast(m.m14),
+                cast(m.m21), cast(m.m22), cast(m.m23), cast(m.m24),
+                cast(m.m31), cast(m.m32), cast(m.m33), cast(m.m34),
+                cast(m.m41), cast(m.m42), cast(m.m43), cast(m.m44),
+            )
+        };
+
+        let (m, is_3d) = Self::components_to_transform_3d_matrix_f64(ops, reference_box)?;
+        Ok((cast_3d_transform(m), is_3d))
+    }
+
+    /// Same as Transform::to_transform_3d_matrix but a f64 version.
+    fn components_to_transform_3d_matrix_f64(
+        ops: &[T],
+        reference_box: Option<&Rect<ComputedLength>>,
+    ) -> Result<(Transform3D<f64>, bool), ()> {
+        // We intentionally use Transform3D<f64> during computation to avoid
+        // error propagation because using f32 to compute triangle functions
+        // (e.g. in rotation()) is not accurate enough. In Gecko, we also use
+        // "double" to compute the triangle functions. Therefore, let's use
+        // Transform3D<f64> during matrix computation and cast it into f32 in
+        // the end.
+        let mut transform = Transform3D::<f64>::identity();
+        let mut contain_3d = false;
+
+        for operation in ops {
+            let matrix = operation.to_3d_matrix(reference_box)?;
+            contain_3d = contain_3d || operation.is_3d();
+            transform = matrix.then(&transform);
+        }
+
+        Ok((transform, contain_3d))
+    }
+}
+
+/// Return the transform matrix from a perspective length.
+#[inline]
+pub fn create_perspective_matrix(d: CSSFloat) -> Transform3D<CSSFloat> {
+    if d.is_finite() {
+        Transform3D::perspective(d.max(1.))
+    } else {
+        Transform3D::identity()
+    }
+}
+
+/// Return the normalized direction vector and its angle for Rotate3D.
+pub fn get_normalized_vector_and_angle<T: Zero>(
+    x: CSSFloat,
+    y: CSSFloat,
+    z: CSSFloat,
+    angle: T,
+) -> (CSSFloat, CSSFloat, CSSFloat, T) {
+    use crate::values::computed::transform::DirectionVector;
+    use euclid::approxeq::ApproxEq;
+    let vector = DirectionVector::new(x, y, z);
+    if vector.square_length().approx_eq(&f32::zero()) {
+        // https://www.w3.org/TR/css-transforms-1/#funcdef-rotate3d
+        // A direction vector that cannot be normalized, such as [0, 0, 0], will cause the
+        // rotation to not be applied, so we use identity matrix (i.e. rotate3d(0, 0, 1, 0)).
+        (0., 0., 1., T::zero())
+    } else {
+        let vector = vector.robust_normalize();
+        (vector.x, vector.y, vector.z, angle)
+    }
+}
+
+#[derive(
+    Clone,
+    Copy,
+    Debug,
+    Deserialize,
+    MallocSizeOf,
+    PartialEq,
+    Serialize,
+    SpecifiedValueInfo,
+    ToAnimatedZero,
+    ToComputedValue,
+    ToResolvedValue,
+    ToShmem,
+)]
+#[repr(C, u8)]
+/// A value of the `Rotate` property
+///
+/// <https://drafts.csswg.org/css-transforms-2/#individual-transforms>
+pub enum GenericRotate<Number, Angle> {
+    /// 'none'
+    None,
+    /// '<angle>'
+    Rotate(Angle),
+    /// '<number>{3} <angle>'
+    Rotate3D(Number, Number, Number, Angle),
+}
+
+pub use self::GenericRotate as Rotate;
+
+/// A trait to check if the current 3D vector is parallel to the DirectionVector.
+/// This is especially for serialization on Rotate.
+pub trait IsParallelTo {
+    /// Returns true if this is parallel to the vector.
+    fn is_parallel_to(&self, vector: &computed::transform::DirectionVector) -> bool;
+}
+
+impl<Number, Angle> ToCss for Rotate<Number, Angle>
+where
+    Number: Copy + ToCss + Zero,
+    Angle: ToCss,
+    (Number, Number, Number): IsParallelTo,
+{
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: fmt::Write,
+    {
+        use crate::values::computed::transform::DirectionVector;
+        match *self {
+            Rotate::None => dest.write_str("none"),
+            Rotate::Rotate(ref angle) => angle.to_css(dest),
+            Rotate::Rotate3D(x, y, z, ref angle) => {
+                // If the axis is parallel with the x or y axes, it must serialize as the
+                // appropriate keyword. If a rotation about the z axis (that is, in 2D) is
+                // specified, the property must serialize as just an <angle>
+                //
+                // https://drafts.csswg.org/css-transforms-2/#individual-transform-serialization
+                let v = (x, y, z);
+                let axis = if x.is_zero() && y.is_zero() && z.is_zero() {
+                    // The zero length vector is parallel to every other vector, so
+                    // is_parallel_to() returns true for it. However, it is definitely different
+                    // from x axis, y axis, or z axis, and it's meaningless to perform a rotation
+                    // using that direction vector. So we *have* to serialize it using that same
+                    // vector - we can't simplify to some theoretically parallel axis-aligned
+                    // vector.
+                    None
+                } else if v.is_parallel_to(&DirectionVector::new(1., 0., 0.)) {
+                    Some("x ")
+                } else if v.is_parallel_to(&DirectionVector::new(0., 1., 0.)) {
+                    Some("y ")
+                } else if v.is_parallel_to(&DirectionVector::new(0., 0., 1.)) {
+                    // When we're parallel to the z-axis, we can just serialize the angle.
+                    return angle.to_css(dest);
+                } else {
+                    None
+                };
+                match axis {
+                    Some(a) => dest.write_str(a)?,
+                    None => {
+                        x.to_css(dest)?;
+                        dest.write_char(' ')?;
+                        y.to_css(dest)?;
+                        dest.write_char(' ')?;
+                        z.to_css(dest)?;
+                        dest.write_char(' ')?;
+                    },
+                }
+                angle.to_css(dest)
+            },
+        }
+    }
+}
+
+#[derive(
+    Clone,
+    Copy,
+    Debug,
+    Deserialize,
+    MallocSizeOf,
+    PartialEq,
+    Serialize,
+    SpecifiedValueInfo,
+    ToAnimatedZero,
+    ToComputedValue,
+    ToResolvedValue,
+    ToShmem,
+)]
+#[repr(C, u8)]
+/// A value of the `Scale` property
+///
+/// <https://drafts.csswg.org/css-transforms-2/#individual-transforms>
+pub enum GenericScale<Number> {
+    /// 'none'
+    None,
+    /// '<number>{1,3}'
+    Scale(Number, Number, Number),
+}
+
+pub use self::GenericScale as Scale;
+
+impl<Number> ToCss for Scale<Number>
+where
+    Number: ToCss + PartialEq + Copy,
+    f32: From<Number>,
+{
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: fmt::Write,
+        f32: From<Number>,
+    {
+        match *self {
+            Scale::None => dest.write_str("none"),
+            Scale::Scale(ref x, ref y, ref z) => {
+                x.to_css(dest)?;
+
+                let is_3d = f32::from(*z) != 1.0;
+                if is_3d || x != y {
+                    dest.write_char(' ')?;
+                    y.to_css(dest)?;
+                }
+
+                if is_3d {
+                    dest.write_char(' ')?;
+                    z.to_css(dest)?;
+                }
+                Ok(())
+            },
+        }
+    }
+}
+
+#[inline]
+fn y_axis_and_z_axis_are_zero<LengthPercentage: Zero + ZeroNoPercent, Length: Zero>(
+    _: &LengthPercentage,
+    y: &LengthPercentage,
+    z: &Length,
+) -> bool {
+    y.is_zero_no_percent() && z.is_zero()
+}
+
+#[derive(
+    Clone,
+    Debug,
+    Deserialize,
+    MallocSizeOf,
+    PartialEq,
+    Serialize,
+    SpecifiedValueInfo,
+    ToAnimatedZero,
+    ToComputedValue,
+    ToCss,
+    ToResolvedValue,
+    ToShmem,
+)]
+#[repr(C, u8)]
+/// A value of the `translate` property
+///
+/// https://drafts.csswg.org/css-transforms-2/#individual-transform-serialization:
+///
+/// If a 2d translation is specified, the property must serialize with only one
+/// or two values (per usual, if the second value is 0px, the default, it must
+/// be omitted when serializing; however if 0% is the second value, it is included).
+///
+/// If a 3d translation is specified and the value can be expressed as 2d, we treat as 2d and
+/// serialize accoringly. Otherwise, we serialize all three values.
+/// https://github.com/w3c/csswg-drafts/issues/3305
+///
+/// <https://drafts.csswg.org/css-transforms-2/#individual-transforms>
+pub enum GenericTranslate<LengthPercentage, Length>
+where
+    LengthPercentage: Zero + ZeroNoPercent,
+    Length: Zero,
+{
+    /// 'none'
+    None,
+    /// <length-percentage> [ <length-percentage> <length>? ]?
+    Translate(
+        LengthPercentage,
+        #[css(contextual_skip_if = "y_axis_and_z_axis_are_zero")] LengthPercentage,
+        #[css(skip_if = "Zero::is_zero")] Length,
+    ),
+}
+
+pub use self::GenericTranslate as Translate;
+
+#[allow(missing_docs)]
+#[derive(
+    Clone,
+    Copy,
+    Debug,
+    MallocSizeOf,
+    Parse,
+    PartialEq,
+    SpecifiedValueInfo,
+    ToComputedValue,
+    ToCss,
+    ToResolvedValue,
+    ToShmem,
+)]
+#[repr(u8)]
+pub enum TransformStyle {
+    Flat,
+    #[css(keyword = "preserve-3d")]
+    Preserve3d,
+}