Auto merge of #26594 - mrobinson:animationiteration, r=jdm

Implement animationiteration event

This event is triggered when an animation iterates. This change also
moves iteration out of style calculation to an "update animations" which
is the next part of having animation event handling match the HTML spec.

This change causes a few more tests to pass. Some of the other tests which
exercise this functionality require `animationstart` events.

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `___` with appropriate data: -->
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [ ] These changes fix #___ (GitHub issue number if applicable)
- [x] There are tests for these changes

<!-- Also, please make sure that "Allow edits from maintainers" checkbox is checked, so that we can help you if you get stuck somewhere along the way.-->

<!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. -->

components/script/animations.rs

@@ -35,6 +35,30 @@ impl Animations {
         }
     }
 
+    pub(crate) fn update_for_new_timeline_value(
+        &mut self,
+        window: &Window,
+        now: f64,
+    ) -> AnimationsUpdate {
+        let mut update = AnimationsUpdate::new(window.pipeline_id());
+        let mut sets = self.sets.write();
+
+        for set in sets.values_mut() {
+            // When necessary, iterate our running animations to the next iteration.
+            for animation in set.animations.iter_mut() {
+                if animation.iterate_if_necessary(now) {
+                    update.add_event(
+                        animation.node,
+                        animation.name.to_string(),
+                        TransitionOrAnimationEventType::AnimationIteration,
+                        animation.active_duration(),
+                    );
+                }
+            }
+        }
+        update
+    }
+
     /// Processes any new animations that were discovered after reflow. Collect messages
     /// that trigger events for any animations that changed state.
     /// TODO(mrobinson): The specification dictates that this should happen before reflow.
@@ -255,6 +279,9 @@ pub enum TransitionOrAnimationEventType {
     TransitionCancel,
     /// "The animationend event occurs when the animation finishes"
     AnimationEnd,
+    /// "The animationiteration event occurs at the end of each iteration of an
+    /// animation, except when an animationend event would fire at the same time."
+    AnimationIteration,
 }
 
 impl TransitionOrAnimationEventType {
@@ -263,7 +290,7 @@ impl TransitionOrAnimationEventType {
     pub fn finalizes_transition_or_animation(&self) -> bool {
         match *self {
             Self::TransitionEnd | Self::TransitionCancel | Self::AnimationEnd => true,
-            Self::TransitionRun => false,
+            Self::TransitionRun | Self::AnimationIteration => false,
         }
     }
 
@@ -271,7 +298,7 @@ impl TransitionOrAnimationEventType {
     pub fn is_transition_event(&self) -> bool {
         match *self {
             Self::TransitionRun | Self::TransitionEnd | Self::TransitionCancel => true,
-            Self::AnimationEnd => false,
+            Self::AnimationEnd | Self::AnimationIteration => false,
         }
     }
 }

components/script/dom/document.rs

@@ -3750,12 +3750,26 @@ impl Document {
             .collect()
     }
 
-    pub(crate) fn advance_animation_timeline_for_testing(&self, delta: f64) {
+    pub(crate) fn advance_animation_timeline_for_testing(&self, delta: f64) -> AnimationsUpdate {
         self.animation_timeline.borrow_mut().advance_specific(delta);
+        let current_timeline_value = self.current_animation_timeline_value();
+        self.animations
+            .borrow_mut()
+            .update_for_new_timeline_value(&self.window, current_timeline_value)
     }
 
-    pub(crate) fn update_animation_timeline(&self) {
-        self.animation_timeline.borrow_mut().update();
+    pub(crate) fn update_animation_timeline(&self) -> AnimationsUpdate {
+        // Only update the time if it isn't being managed by a test.
+        if !pref!(layout.animations.test.enabled) {
+            self.animation_timeline.borrow_mut().update();
+        }
+
+        // We still want to update the animations, because our timeline
+        // value might have been advanced previously via the TestBinding.
+        let current_timeline_value = self.current_animation_timeline_value();
+        self.animations
+            .borrow_mut()
+            .update_for_new_timeline_value(&self.window, current_timeline_value)
     }
 
     pub(crate) fn current_animation_timeline_value(&self) -> f64 {
@@ -3766,7 +3780,7 @@ impl Document {
         self.animations.borrow()
     }
 
-    pub(crate) fn update_animations(&self) -> AnimationsUpdate {
+    pub(crate) fn update_animations_post_reflow(&self) -> AnimationsUpdate {
         self.animations
             .borrow_mut()
             .do_post_reflow_update(&self.window, self.current_animation_timeline_value())

components/script/dom/macros.rs

@@ -443,6 +443,7 @@ macro_rules! global_event_handlers(
     (NoOnload) => (
         event_handler!(abort, GetOnabort, SetOnabort);
         event_handler!(animationend, GetOnanimationend, SetOnanimationend);
+        event_handler!(animationiteration, GetOnanimationiteration, SetOnanimationiteration);
         event_handler!(cancel, GetOncancel, SetOncancel);
         event_handler!(canplay, GetOncanplay, SetOncanplay);
         event_handler!(canplaythrough, GetOncanplaythrough, SetOncanplaythrough);

components/script/dom/webidls/EventHandler.webidl

@@ -93,6 +93,7 @@ interface mixin GlobalEventHandlers {
 // https://drafts.csswg.org/css-animations/#interface-globaleventhandlers-idl
 partial interface mixin GlobalEventHandlers {
            attribute EventHandler onanimationend;
+           attribute EventHandler onanimationiteration;
 };
 
 // https://drafts.csswg.org/css-transitions/#interface-globaleventhandlers-idl

components/script/dom/window.rs

@@ -1578,10 +1578,15 @@ impl Window {
 
     /// Prepares to tick animations and then does a reflow which also advances the
     /// layout animation clock.
-    pub fn advance_animation_clock(&self, delta: i32) {
+    #[allow(unsafe_code)]
+    pub fn advance_animation_clock(&self, delta_ms: i32) {
         let pipeline_id = self.upcast::<GlobalScope>().pipeline_id();
-        self.Document()
-            .advance_animation_timeline_for_testing(delta as f64 / 1000.);
+        let update = self
+            .Document()
+            .advance_animation_timeline_for_testing(delta_ms as f64 / 1000.);
+        unsafe {
+            ScriptThread::process_animations_update(update);
+        }
         ScriptThread::handle_tick_all_animations_for_testing(pipeline_id);
     }
 
@@ -1747,7 +1752,7 @@ impl Window {
             }
         }
 
-        let update = document.update_animations();
+        let update = document.update_animations_post_reflow();
         unsafe {
             ScriptThread::process_animations_update(update);
         }

components/script/script_thread.rs

@@ -149,7 +149,6 @@ use script_traits::{
 };
 use servo_atoms::Atom;
 use servo_config::opts;
-use servo_config::pref;
 use servo_url::{ImmutableOrigin, MutableOrigin, ServoUrl};
 use std::borrow::Cow;
 use std::cell::Cell;
@@ -1631,19 +1630,17 @@ impl ScriptThread {
     // TODO(mrobinson): This should also update the current animations to conform to
     // the HTML specification.
     fn update_animations_and_send_events(&self) {
-        for (_, document) in self.documents.borrow().iter() {
-            // Only update the time if it isn't being managed by a test.
-            if !pref!(layout.animations.test.enabled) {
-                document.update_animation_timeline();
-            }
-        }
-
         // We remove the events because handling these events might trigger
         // a reflow which might want to add more events to the queue.
         let events = self.animation_events.replace(Vec::new());
         for event in events.into_iter() {
             self.handle_transition_or_animation_event(&event);
         }
+
+        for (_, document) in self.documents.borrow().iter() {
+            let update = document.update_animation_timeline();
+            unsafe { ScriptThread::process_animations_update(update) };
+        }
     }
 
     fn categorize_msg(&self, msg: &MixedMessage) -> ScriptThreadEventCategory {
@@ -2947,6 +2944,7 @@ impl ScriptThread {
 
         let event_atom = match event.event_type {
             TransitionOrAnimationEventType::AnimationEnd => atom!("animationend"),
+            TransitionOrAnimationEventType::AnimationIteration => atom!("animationiteration"),
             TransitionOrAnimationEventType::TransitionCancel => atom!("transitioncancel"),
             TransitionOrAnimationEventType::TransitionEnd => atom!("transitionend"),
             TransitionOrAnimationEventType::TransitionRun => atom!("transitionrun"),