style: Part 1: Add animation-timeline longhand property in style system

This patch adds the animation-timeline longhand property. For
shorthand, we will do that in the next patch.

This patch includes the aut-generated code in
devtools/shared/css/generated/properties-db.js, by `./mach devtools-css-db`.

Note:
1. we will use this property in Bug 1676791. For now, only make sure
   we parse it and serialize it correctly.
2. The syntax of animation-timeline may be updated, based on the spec
   issue: w3c/csswg-drafts#6674.
   However, it's not a big problem to update it later, so we still can
   prototype this property based on the current version of spec.

Differential Revision: https://phabricator.services.mozilla.com/D126450

components/style/properties/gecko.mako.rs

@@ -1049,7 +1049,7 @@ fn static_assert() {
             % if member:
             ours.m${gecko_ffi_name}.${member} = others.m${gecko_ffi_name}.${member};
             % else:
-            ours.m${gecko_ffi_name} = others.m${gecko_ffi_name};
+            ours.m${gecko_ffi_name} = others.m${gecko_ffi_name}.clone();
             % endif
         }
     }
@@ -1183,7 +1183,7 @@ fn static_assert() {
 <% skip_box_longhands= """display
                           animation-name animation-delay animation-duration
                           animation-direction animation-fill-mode animation-play-state
-                          animation-iteration-count animation-timing-function
+                          animation-iteration-count animation-timeline animation-timing-function
                           clear transition-duration transition-delay
                           transition-timing-function transition-property
                           -webkit-line-clamp""" %>
@@ -1445,6 +1445,27 @@ fn static_assert() {
     ${impl_copy_animation_value('iteration_count', 'IterationCount')}
     ${impl_animation_or_transition_timing_function('animation')}
 
+    pub fn set_animation_timeline<I>(&mut self, v: I)
+    where
+        I: IntoIterator<Item = longhands::animation_timeline::computed_value::single_value::T>,
+        I::IntoIter: ExactSizeIterator
+    {
+        let v = v.into_iter();
+        debug_assert_ne!(v.len(), 0);
+        let input_len = v.len();
+        self.gecko.mAnimations.ensure_len(input_len);
+
+        self.gecko.mAnimationTimelineCount = input_len as u32;
+        for (gecko, servo) in self.gecko.mAnimations.iter_mut().take(input_len as usize).zip(v) {
+            gecko.mTimeline = servo;
+        }
+    }
+    pub fn animation_timeline_at(&self, index: usize) -> values::specified::box_::AnimationTimeline {
+        self.gecko.mAnimations[index].mTimeline.clone()
+    }
+    ${impl_animation_count('timeline', 'Timeline')}
+    ${impl_copy_animation_value('timeline', 'Timeline')}
+
     #[allow(non_snake_case)]
     pub fn set__webkit_line_clamp(&mut self, v: longhands::_webkit_line_clamp::computed_value::T) {
         self.gecko.mLineClamp = match v {

components/style/properties/longhands/box.mako.rs

@@ -320,6 +320,20 @@ ${helpers.predefined_type(
     rule_types_allowed=DEFAULT_RULES_EXCEPT_KEYFRAME,
 )}
 
+${helpers.predefined_type(
+    "animation-timeline",
+    "AnimationTimeline",
+    "computed::AnimationTimeline::auto()",
+    engines="gecko",
+    initial_specified_value="specified::AnimationTimeline::auto()",
+    vector=True,
+    need_index=True,
+    animation_value_type="none",
+    gecko_pref="layout.css.scroll-linked-animations.enabled",
+    spec="https://drafts.csswg.org/css-animations-2/#propdef-animation-timeline",
+    rule_types_allowed=DEFAULT_RULES_EXCEPT_KEYFRAME,
+)}
+
 <% transform_extra_prefixes = "moz:layout.css.prefixes.transforms webkit" %>
 
 ${helpers.predefined_type(

components/style/properties/properties.mako.rs

@@ -2921,7 +2921,7 @@ pub mod style_structs {
             }
 
             /// Returns true if animation properties are equal between styles, but without
-            /// considering keyframe data.
+            /// considering keyframe data and animation-timeline.
             #[cfg(feature = "servo")]
             pub fn animations_equals(&self, other: &Self) -> bool {
                 self.animation_name_iter().eq(other.animation_name_iter()) &&

components/style/stylist.rs

@@ -2301,8 +2301,12 @@ impl CascadeData {
                 },
                 #[cfg(feature = "gecko")]
                 CssRule::ScrollTimeline(..) => {
-                    // TODO: Bug 1676784: set the timeline into animation.
-                }
+                    // TODO: Bug 1676791: set the timeline into animation.
+                    // https://phabricator.services.mozilla.com/D126452
+                    //
+                    // Note: Bug 1733260: we may drop @scroll-timeline rule once this spec issue
+                    // https://github.com/w3c/csswg-drafts/issues/6674 gets landed.
+                },
                 #[cfg(feature = "gecko")]
                 CssRule::FontFace(ref rule) => {
                     self.extra_data.add_font_face(rule);

components/style/values/computed/box.rs

@@ -11,14 +11,12 @@ use crate::values::generics::box_::Perspective as GenericPerspective;
 use crate::values::generics::box_::VerticalAlign as GenericVerticalAlign;
 use crate::values::specified::box_ as specified;
 
-pub use crate::values::specified::box_::Clear as SpecifiedClear;
-pub use crate::values::specified::box_::{AnimationName, Appearance, BreakBetween, BreakWithin};
-pub use crate::values::specified::box_::{Contain, Display, Float as SpecifiedFloat, Overflow};
-pub use crate::values::specified::box_::{OverflowAnchor, OverflowClipBox, OverscrollBehavior};
 pub use crate::values::specified::box_::{
-    ScrollSnapAlign, ScrollSnapAxis, ScrollSnapStrictness, ScrollSnapType,
+    AnimationName, AnimationTimeline, Appearance, BreakBetween, BreakWithin,
+    Clear as SpecifiedClear, Contain, Display, Float as SpecifiedFloat, Overflow, OverflowAnchor,
+    OverflowClipBox, OverscrollBehavior, ScrollSnapAlign, ScrollSnapAxis, ScrollSnapStrictness,
+    ScrollSnapType, TouchAction, TransitionProperty, WillChange,
 };
-pub use crate::values::specified::box_::{TouchAction, TransitionProperty, WillChange};
 
 /// A computed value for the `vertical-align` property.
 pub type VerticalAlign = GenericVerticalAlign<LengthPercentage>;

components/style/values/computed/mod.rs

@@ -44,7 +44,7 @@ pub use self::basic_shape::FillRule;
 pub use self::border::{BorderCornerRadius, BorderRadius, BorderSpacing};
 pub use self::border::{BorderImageRepeat, BorderImageSideWidth};
 pub use self::border::{BorderImageSlice, BorderImageWidth};
-pub use self::box_::{AnimationIterationCount, AnimationName, Contain};
+pub use self::box_::{AnimationIterationCount, AnimationName, AnimationTimeline, Contain};
 pub use self::box_::{Appearance, BreakBetween, BreakWithin, Clear, Float};
 pub use self::box_::{Display, Overflow, OverflowAnchor, TransitionProperty};
 pub use self::box_::{OverflowClipBox, OverscrollBehavior, Perspective, Resize};

components/style/values/mod.rs

@@ -472,6 +472,7 @@ impl ToCss for CustomIdent {
 #[derive(
     Clone, Debug, MallocSizeOf, SpecifiedValueInfo, ToComputedValue, ToResolvedValue, ToShmem,
 )]
+#[repr(C, u8)]
 pub enum TimelineOrKeyframesName {
     /// <custom-ident>
     Ident(CustomIdent),

components/style/values/specified/box.rs

@@ -13,7 +13,7 @@ use crate::values::generics::box_::Perspective as GenericPerspective;
 use crate::values::generics::box_::{GenericVerticalAlign, VerticalAlignKeyword};
 use crate::values::specified::length::{LengthPercentage, NonNegativeLength};
 use crate::values::specified::{AllowQuirks, Number};
-use crate::values::{CustomIdent, KeyframesName};
+use crate::values::{CustomIdent, KeyframesName, TimelineName};
 use crate::Atom;
 use cssparser::Parser;
 use num_traits::FromPrimitive;
@@ -762,6 +762,62 @@ impl Parse for AnimationName {
     }
 }
 
+/// A value for the <single-animation-timeline>.
+///
+/// https://drafts.csswg.org/css-animations-2/#typedef-single-animation-timeline
+/// cbindgen:private-default-tagged-enum-constructor=false
+#[derive(
+    Clone,
+    Debug,
+    Eq,
+    Hash,
+    MallocSizeOf,
+    PartialEq,
+    SpecifiedValueInfo,
+    ToComputedValue,
+    ToCss,
+    ToResolvedValue,
+    ToShmem,
+)]
+#[repr(C, u8)]
+pub enum AnimationTimeline {
+    /// Use default timeline. The animation’s timeline is a DocumentTimeline.
+    Auto,
+    /// The animation is not associated with a timeline.
+    None,
+    /// The scroll-timeline name
+    Timeline(TimelineName),
+}
+
+impl AnimationTimeline {
+    /// Returns the `auto` value.
+    pub fn auto() -> Self {
+        Self::Auto
+    }
+}
+
+impl Parse for AnimationTimeline {
+    fn parse<'i, 't>(
+        context: &ParserContext,
+        input: &mut Parser<'i, 't>,
+    ) -> Result<Self, ParseError<'i>> {
+        // We are using the same parser for TimelineName and KeyframesName, but animation-timeline
+        // accepts "auto", so need to manually parse this. (We can not derive Parse because
+        // TimelineName excludes only "none" keyword.)
+        // FIXME: Bug 1733260: we may drop None based on the spec issue:
+        // Note: https://github.com/w3c/csswg-drafts/issues/6674.
+        if input.try_parse(|i| i.expect_ident_matching("auto")).is_ok() {
+            return Ok(Self::Auto);
+        }
+
+        if input.try_parse(|i| i.expect_ident_matching("none")).is_ok() {
+            return Ok(Self::None);
+        }
+
+        TimelineName::parse(context, input).map(AnimationTimeline::Timeline)
+    }
+}
+
 /// https://drafts.csswg.org/css-scroll-snap-1/#snap-axis
 #[allow(missing_docs)]
 #[cfg_attr(feature = "servo", derive(Deserialize, Serialize))]

components/style/values/specified/mod.rs

@@ -36,7 +36,7 @@ pub use self::basic_shape::FillRule;
 pub use self::border::{BorderCornerRadius, BorderImageSlice, BorderImageWidth};
 pub use self::border::{BorderImageRepeat, BorderImageSideWidth};
 pub use self::border::{BorderRadius, BorderSideWidth, BorderSpacing, BorderStyle};
-pub use self::box_::{AnimationIterationCount, AnimationName, Contain, Display};
+pub use self::box_::{AnimationIterationCount, AnimationName, AnimationTimeline, Contain, Display};
 pub use self::box_::{Appearance, BreakBetween, BreakWithin};
 pub use self::box_::{Clear, Float, Overflow, OverflowAnchor};
 pub use self::box_::{OverflowClipBox, OverscrollBehavior, Perspective, Resize};