Emit TransitionEnd events in the layout thread and process it in the script thread

components/script/dom/bindings/js.rs

@@ -444,6 +444,14 @@ impl<T: Reflectable> LayoutJS<T> {
         debug_assert!(thread_state::get().is_layout());
         *self.ptr
     }
+
+    /// Returns a reference to the interior of this JS object. This method is
+    /// safe to call because it originates from the layout thread, and it cannot
+    /// mutate DOM nodes.
+    pub fn get_for_script(&self) -> &T {
+        debug_assert!(thread_state::get().is_script());
+        unsafe { &**self.ptr }
+    }
 }
 
 /// Get an `&T` out of a `Rc<T>`

components/script/dom/macros.rs

@@ -472,6 +472,7 @@ macro_rules! global_event_handlers(
         event_handler!(suspend, GetOnsuspend, SetOnsuspend);
         event_handler!(timeupdate, GetOntimeupdate, SetOntimeupdate);
         event_handler!(toggle, GetOntoggle, SetOntoggle);
+        event_handler!(transitionend, GetOntransitionend, SetOntransitionend);
         event_handler!(volumechange, GetOnvolumechange, SetOnvolumechange);
         event_handler!(waiting, GetOnwaiting, SetOnwaiting);
     )

components/script/dom/webidls/EventHandler.webidl

@@ -89,6 +89,11 @@ interface GlobalEventHandlers {
            attribute EventHandler onwaiting;
 };
 
+// https://drafts.csswg.org/css-transitions/#interface-globaleventhandlers-idl
+partial interface GlobalEventHandlers {
+           attribute EventHandler ontransitionend;
+};
+
 // https://html.spec.whatwg.org/multipage/#windoweventhandlers
 [NoInterfaceObject, Exposed=(Window,Worker)]
 interface WindowEventHandlers {

components/script/dom/webidls/TransitionEvent.webidl

@@ -6,7 +6,8 @@
  * https://dom.spec.whatwg.org/#event
  */
 
-[Constructor(DOMString type, optional TransitionEventInit transitionEventInitDict)]
+[Constructor(DOMString type, optional TransitionEventInit transitionEventInitDict),
+ Exposed=Window]
 interface TransitionEvent : Event {
   readonly attribute DOMString          propertyName;
   readonly attribute float              elapsedTime;

components/script/layout_wrapper.rs

@@ -413,7 +413,7 @@ impl<'ln> ServoLayoutNode<'ln> {
 
     /// Returns the interior of this node as a `LayoutJS`. This is highly unsafe for layout to
     /// call and as such is marked `unsafe`.
-    unsafe fn get_jsmanaged(&self) -> &LayoutJS<Node> {
+    pub unsafe fn get_jsmanaged(&self) -> &LayoutJS<Node> {
         &self.node
     }
 }

components/script/script_thread.rs

@@ -23,13 +23,17 @@ use devtools_traits::{ScriptToDevtoolsControlMsg, WorkerId};
 use devtools_traits::CSSError;
 use document_loader::DocumentLoader;
 use dom::bindings::cell::DOMRefCell;
+use dom::bindings::codegen::Bindings::CSSStyleDeclarationBinding::CSSStyleDeclarationMethods;
 use dom::bindings::codegen::Bindings::DocumentBinding::{DocumentMethods, DocumentReadyState};
+use dom::bindings::codegen::Bindings::EventBinding::EventInit;
 use dom::bindings::codegen::Bindings::LocationBinding::LocationMethods;
+use dom::bindings::codegen::Bindings::TransitionEventBinding::TransitionEventInit;
 use dom::bindings::codegen::Bindings::WindowBinding::WindowMethods;
 use dom::bindings::conversions::{ConversionResult, FromJSValConvertible, StringificationBehavior};
 use dom::bindings::inheritance::Castable;
 use dom::bindings::js::{JS, MutNullableHeap, Root, RootCollection};
 use dom::bindings::js::{RootCollectionPtr, RootedReference};
+use dom::bindings::num::Finite;
 use dom::bindings::refcounted::Trusted;
 use dom::bindings::reflector::Reflectable;
 use dom::bindings::str::DOMString;
@@ -47,6 +51,7 @@ use dom::serviceworkerregistration::ServiceWorkerRegistration;
 use dom::servoparser::{ParserContext, ServoParser};
 use dom::servoparser::html::{ParseContext, parse_html};
 use dom::servoparser::xml::{self, parse_xml};
+use dom::transitionevent::TransitionEvent;
 use dom::uievent::UIEvent;
 use dom::window::{ReflowReason, Window};
 use dom::worker::TrustedWorkerAddress;
@@ -65,6 +70,7 @@ use js::jsapi::{JSAutoCompartment, JSContext, JS_SetWrapObjectCallbacks};
 use js::jsapi::{JSTracer, SetWindowProxyClass};
 use js::jsval::UndefinedValue;
 use js::rust::Runtime;
+use layout_wrapper::ServoLayoutNode;
 use mem::heap_size_of_self_and_children;
 use msg::constellation_msg::{FrameType, LoadData, PipelineId, PipelineNamespace};
 use msg::constellation_msg::{ReferrerPolicy, WindowSizeType};
@@ -97,6 +103,7 @@ use std::sync::{Arc, Mutex};
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::mpsc::{Receiver, Select, Sender, channel};
 use style::context::ReflowGoal;
+use style::dom::{TNode, UnsafeNode};
 use style::thread_state;
 use task_source::TaskSource;
 use task_source::dom_manipulation::{DOMManipulationTask, DOMManipulationTaskSource};
@@ -917,6 +924,8 @@ impl ScriptThread {
                 self.handle_webdriver_msg(pipeline_id, msg),
             ConstellationControlMsg::TickAllAnimations(pipeline_id) =>
                 self.handle_tick_all_animations(pipeline_id),
+            ConstellationControlMsg::TransitionEnd(unsafe_node, name, duration) =>
+                self.handle_transition_event(unsafe_node, name, duration),
             ConstellationControlMsg::WebFontLoaded(pipeline_id) =>
                 self.handle_web_font_loaded(pipeline_id),
             ConstellationControlMsg::DispatchFrameLoadEvent {
@@ -1523,6 +1532,35 @@ impl ScriptThread {
         document.run_the_animation_frame_callbacks();
     }
 
+    /// Handles firing of transition events.
+    #[allow(unsafe_code)]
+    fn handle_transition_event(&self, unsafe_node: UnsafeNode, name: String, duration: f64) {
+        let node = unsafe { ServoLayoutNode::from_unsafe(&unsafe_node) };
+        let node = unsafe { node.get_jsmanaged().get_for_script() };
+        let window = window_from_node(node);
+
+        if let Some(el) = node.downcast::<Element>() {
+            if &*window.GetComputedStyle(el, None).Display() == "none" {
+                return;
+            }
+        }
+
+        let init = TransitionEventInit {
+            parent: EventInit {
+                bubbles: true,
+                cancelable: false,
+            },
+            propertyName: DOMString::from(name),
+            elapsedTime: Finite::new(duration as f32).unwrap(),
+            // FIXME: Handle pseudo-elements properly
+            pseudoElement: DOMString::new()
+        };
+        let transition_event = TransitionEvent::new(window.upcast(),
+                                                    atom!("transitionend"),
+                                                    &init);
+        transition_event.upcast::<Event>().fire(node.upcast());
+    }
+
     /// Handles a Web font being loaded. Does nothing if the page no longer exists.
     fn handle_web_font_loaded(&self, pipeline_id: PipelineId) {
         if let Some(context) = self.find_child_context(pipeline_id)  {