Consider shadow dom when dispatching events (#34788)

* Implement EventTarget::get_the_parent

Signed-off-by: Simon Wülker <simon.wuelker@arcor.de>

* Add spec steps to Event::init_event

Signed-off-by: Simon Wülker <simon.wuelker@arcor.de>

* Rewrite Event::composedPath to be spec compliant

Signed-off-by: Simon Wülker <simon.wuelker@arcor.de>

* Retarget EventTargets instead of Nodes

Signed-off-by: Simon Wülker <simon.wuelker@arcor.de>

* Rewrite event dispatch/invocation to better match the spec

Signed-off-by: Simon Wülker <simon.wuelker@arcor.de>

* Add spec comments to Event struct

Signed-off-by: Simon Wülker <simon.wuelker@arcor.de>

* Don't traverse shadow roots when calculating an events path

We can't do this correctly yet, and assuming that an events
composed flag is never set is correct 99% of the time.

Signed-off-by: Simon Wülker <simon.wuelker@arcor.de>

* Fix typo in event dispatch

Signed-off-by: Simon Wülker <simon.wuelker@arcor.de>

* fix comment

Signed-off-by: Simon Wülker <simon.wuelker@arcor.de>

* Update WPT expectations

Signed-off-by: Simon Wülker <simon.wuelker@arcor.de>

* allow crown error

Signed-off-by: Simon Wülker <simon.wuelker@arcor.de>

* fmt

Signed-off-by: Simon Wülker <simon.wuelker@arcor.de>

* Reduce item visibility where possible

Signed-off-by: Simon Wülker <simon.wuelker@arcor.de>

* Simplify code a bit

Signed-off-by: Simon Wülker <simon.wuelker@arcor.de>

* Fix Step 5.10 of Event::invoke

Signed-off-by: Simon Wülker <simon.wuelker@arcor.de>

* Fix renamed method calls

Signed-off-by: Simon Wülker <simon.wuelker@arcor.de>

---------

Signed-off-by: Simon Wülker <simon.wuelker@arcor.de>

components/script/dom/eventtarget.rs

@@ -24,7 +24,6 @@ use libc::c_char;
 use servo_atoms::Atom;
 use servo_url::ServoUrl;
 
-use super::bindings::trace::HashMapTracedValues;
 use crate::dom::beforeunloadevent::BeforeUnloadEvent;
 use crate::dom::bindings::callback::{CallbackContainer, CallbackFunction, ExceptionHandling};
 use crate::dom::bindings::cell::DomRefCell;
@@ -38,6 +37,9 @@ use crate::dom::bindings::codegen::Bindings::EventListenerBinding::EventListener
 use crate::dom::bindings::codegen::Bindings::EventTargetBinding::{
     AddEventListenerOptions, EventListenerOptions, EventTargetMethods,
 };
+use crate::dom::bindings::codegen::Bindings::NodeBinding::GetRootNodeOptions;
+use crate::dom::bindings::codegen::Bindings::NodeBinding::Node_Binding::NodeMethods;
+use crate::dom::bindings::codegen::Bindings::ShadowRootBinding::ShadowRoot_Binding::ShadowRootMethods;
 use crate::dom::bindings::codegen::Bindings::WindowBinding::WindowMethods;
 use crate::dom::bindings::codegen::UnionTypes::{
     AddEventListenerOptionsOrBoolean, EventListenerOptionsOrBoolean, EventOrString,
@@ -47,12 +49,15 @@ use crate::dom::bindings::inheritance::Castable;
 use crate::dom::bindings::reflector::{reflect_dom_object_with_proto, DomObject, Reflector};
 use crate::dom::bindings::root::DomRoot;
 use crate::dom::bindings::str::DOMString;
+use crate::dom::bindings::trace::HashMapTracedValues;
+use crate::dom::document::Document;
 use crate::dom::element::Element;
 use crate::dom::errorevent::ErrorEvent;
 use crate::dom::event::{Event, EventBubbles, EventCancelable, EventStatus};
 use crate::dom::globalscope::GlobalScope;
 use crate::dom::htmlformelement::FormControlElementHelpers;
-use crate::dom::node::NodeTraits;
+use crate::dom::node::{Node, NodeTraits};
+use crate::dom::shadowroot::ShadowRoot;
 use crate::dom::virtualmethods::VirtualMethods;
 use crate::dom::window::Window;
 use crate::dom::workerglobalscope::WorkerGlobalScope;
@@ -781,6 +786,67 @@ impl EventTarget {
             }
         }
     }
+
+    /// <https://dom.spec.whatwg.org/#get-the-parent>
+    pub(crate) fn get_the_parent(&self, event: &Event) -> Option<DomRoot<EventTarget>> {
+        if let Some(document) = self.downcast::<Document>() {
+            if event.type_() == atom!("load") || !document.has_browsing_context() {
+                return None;
+            } else {
+                return Some(DomRoot::from_ref(document.window().upcast::<EventTarget>()));
+            }
+        }
+
+        if self.downcast::<ShadowRoot>().is_some() {
+            // FIXME: Handle event composed flag here
+            // We currently assume that events are never composed (so events may never
+            // cross a shadow boundary)
+            return None;
+        }
+
+        if let Some(node) = self.downcast::<Node>() {
+            // FIXME: Handle slottables here
+            let parent = node.GetParentNode()?;
+            return Some(DomRoot::from_ref(parent.upcast::<EventTarget>()));
+        }
+
+        None
+    }
+
+    // FIXME: This algorithm operates on "objects", which may not be event targets.
+    // All our current use-cases only work on event targets, but this might change in the future
+    /// <https://dom.spec.whatwg.org/#retarget>
+    pub(crate) fn retarget(&self, b: &Self) -> DomRoot<EventTarget> {
+        // To retarget an object A against an object B, repeat these steps until they return an object:
+        let mut a = DomRoot::from_ref(self);
+        loop {
+            // Step 1. If one of the following is true
+            // * A is not a node
+            // * A’s root is not a shadow root
+            // * B is a node and A’s root is a shadow-including inclusive ancestor of B
+            let Some(a_node) = a.downcast::<Node>() else {
+                return a;
+            };
+            let a_root = a_node.GetRootNode(&GetRootNodeOptions::empty());
+            if !a_root.is::<ShadowRoot>() {
+                return a;
+            }
+            if let Some(b_node) = b.downcast::<Node>() {
+                if a_root.is_shadow_including_inclusive_ancestor_of(b_node) {
+                    return a;
+                }
+            }
+
+            // Step 2. Set A to A’s root’s host.
+            a = DomRoot::from_ref(
+                a_root
+                    .downcast::<ShadowRoot>()
+                    .unwrap()
+                    .Host()
+                    .upcast::<EventTarget>(),
+            );
+        }
+    }
 }
 
 impl EventTargetMethods<crate::DomTypeHolder> for EventTarget {

components/script/dom/node.rs

@@ -612,6 +612,7 @@ impl Node {
         self.flags.get().contains(NodeFlags::IS_IN_A_DOCUMENT_TREE)
     }
 
+    /// Return true iff node's root is a shadow-root.
     pub fn is_in_a_shadow_tree(&self) -> bool {
         self.flags.get().contains(NodeFlags::IS_IN_SHADOW_TREE)
     }
@@ -1281,27 +1282,6 @@ impl Node {
         }
     }
 
-    /// <https://dom.spec.whatwg.org/#retarget>
-    pub fn retarget(&self, b: &Node) -> DomRoot<Node> {
-        let mut a = DomRoot::from_ref(self);
-        loop {
-            // Step 1.
-            let a_root = a.GetRootNode(&GetRootNodeOptions::empty());
-            if !a_root.is::<ShadowRoot>() || a_root.is_shadow_including_inclusive_ancestor_of(b) {
-                return DomRoot::from_ref(&a);
-            }
-
-            // Step 2.
-            a = DomRoot::from_ref(
-                a_root
-                    .downcast::<ShadowRoot>()
-                    .unwrap()
-                    .Host()
-                    .upcast::<Node>(),
-            );
-        }
-    }
-
     pub fn is_styled(&self) -> bool {
         self.style_data.borrow().is_some()
     }

components/script/dom/shadowroot.rs

@@ -28,6 +28,7 @@ use crate::dom::node::{
     BindContext, Node, NodeDamage, NodeFlags, NodeTraits, ShadowIncluding, UnbindContext,
 };
 use crate::dom::stylesheetlist::{StyleSheetList, StyleSheetListOwner};
+use crate::dom::types::EventTarget;
 use crate::dom::virtualmethods::VirtualMethods;
 use crate::dom::window::Window;
 use crate::script_runtime::CanGc;
@@ -218,7 +219,9 @@ impl ShadowRootMethods<crate::DomTypeHolder> for ShadowRoot {
             can_gc,
         ) {
             Some(e) => {
-                let retargeted_node = self.upcast::<Node>().retarget(e.upcast::<Node>());
+                let retargeted_node = self
+                    .upcast::<EventTarget>()
+                    .retarget(e.upcast::<EventTarget>());
                 retargeted_node.downcast::<Element>().map(DomRoot::from_ref)
             },
             None => None,
@@ -240,7 +243,9 @@ impl ShadowRootMethods<crate::DomTypeHolder> for ShadowRoot {
             .elements_from_point(x, y, None, self.document.has_browsing_context(), can_gc)
             .iter()
         {
-            let retargeted_node = self.upcast::<Node>().retarget(e.upcast::<Node>());
+            let retargeted_node = self
+                .upcast::<EventTarget>()
+                .retarget(e.upcast::<EventTarget>());
             if let Some(element) = retargeted_node.downcast::<Element>().map(DomRoot::from_ref) {
                 elements.push(element);
             }

components/script/dom/window.rs

@@ -1601,12 +1601,15 @@ impl Window {
         window_named_properties::create(cx, proto, object)
     }
 
-    pub(crate) fn set_current_event(&self, event: Option<&Event>) -> Option<DomRoot<Event>> {
+    pub(crate) fn current_event(&self) -> Option<DomRoot<Event>> {
-        let current = self
+        self.current_event
-            .current_event
             .borrow()
             .as_ref()
-            .map(|e| DomRoot::from_ref(&**e));
+            .map(|e| DomRoot::from_ref(&**e))
+    }
+
+    pub(crate) fn set_current_event(&self, event: Option<&Event>) -> Option<DomRoot<Event>> {
+        let current = self.current_event();
         *self.current_event.borrow_mut() = event.map(Dom::from_ref);
         current
     }

tests/wpt/meta/dom/events/Event-dispatch-click.html.ini

@@ -1,6 +0,0 @@
-[Event-dispatch-click.html]
-  [event state during post-click handling]
-    expected: FAIL
-
-  [submit button should not activate if the event listener disables it]
-    expected: FAIL

tests/wpt/meta/dom/events/EventTarget-constructible.any.js.ini

@@ -1,8 +0,0 @@
-[EventTarget-constructible.any.worker.html]
-  [A constructed EventTarget implements dispatch correctly]
-    expected: FAIL
-
-
-[EventTarget-constructible.any.html]
-  [A constructed EventTarget implements dispatch correctly]
-    expected: FAIL

tests/wpt/meta/dom/events/event-global.html.ini

@@ -1,6 +1,7 @@
 [event-global.html]
+  expected: TIMEOUT
   [window.event is undefined if the target is in a shadow tree (event dispatched inside shadow tree)]
-    expected: FAIL
+    expected: TIMEOUT
 
   [window.event is undefined inside window.onerror if the target is in a shadow tree (ErrorEvent dispatched inside shadow tree)]
     expected: FAIL

tests/wpt/meta/shadow-dom/Extensions-to-Event-Interface.html.ini

@@ -1,7 +1,4 @@
 [Extensions-to-Event-Interface.html]
-  [composedPath() must return an empty array when the event is no longer dispatched]
-    expected: FAIL
-
   [composed on EventInit must default to false]
     expected: FAIL
 

tests/wpt/meta/shadow-dom/event-post-dispatch.html.ini

@@ -1,28 +1,13 @@
 [event-post-dispatch.html]
-  [Event properties post dispatch without ShadowRoots (composed: true).]
-    expected: FAIL
-
-  [Event properties post dispatch without ShadowRoots (composed: false).]
-    expected: FAIL
-
   [Event properties post dispatch with an open ShadowRoot (composed: true).]
     expected: FAIL
 
-  [Event properties post dispatch with an open ShadowRoot (composed: false).]
-    expected: FAIL
-
   [Event properties post dispatch with a closed ShadowRoot (composed: true).]
     expected: FAIL
 
-  [Event properties post dispatch with a closed ShadowRoot (composed: false).]
-    expected: FAIL
-
   [Event properties post dispatch with nested ShadowRoots (composed: true).]
     expected: FAIL
 
-  [Event properties post dispatch with nested ShadowRoots (composed: false).]
-    expected: FAIL
-
   [Event properties post dispatch with relatedTarget in the same shadow tree. (composed: true)]
     expected: FAIL
 
@@ -43,6 +28,3 @@
 
   [Event properties post dispatch when target get moved out of the shadow tree by event listener]
     expected: FAIL
-
-  [Event properties post dispatch when target get moved into the the shadow tree by event listener]
-    expected: FAIL