constellation: notify embedder when events are hit-tested to browsers (#30841)

* constellation: notify embedder when events are hit-tested to browsers

* fix compile error in libsimpleservo

* impl From<&CompositorEvent> for CompositorEventVariant

* remove msg temporaries in Constellation::forward_event

* use single wildcard arm in EventDelivered case in handle_servo_events

components/constellation/constellation.rs

@@ -1548,9 +1548,10 @@ where
 
     fn handle_request_from_script(&mut self, message: (PipelineId, FromScriptMsg)) {
         let (source_pipeline_id, content) = message;
-        debug!(
+        trace!(
             "{}: Message from pipeline: {:?}",
-            source_pipeline_id, content,
+            source_pipeline_id,
+            content,
         );
 
         let source_top_ctx_id = match self
@@ -2904,15 +2905,23 @@ where
             self.pressed_mouse_buttons = 0;
         }
 
-        let msg = ConstellationControlMsg::SendEvent(destination_pipeline_id, event);
-        let result = match self.pipelines.get(&destination_pipeline_id) {
+        let pipeline = match self.pipelines.get(&destination_pipeline_id) {
             None => {
                 debug!("{}: Got event after closure", destination_pipeline_id);
                 return;
             },
-            Some(pipeline) => pipeline.event_loop.send(msg),
+            Some(pipeline) => pipeline,
         };
-        if let Err(e) = result {
+
+        self.embedder_proxy.send((
+            Some(pipeline.top_level_browsing_context_id),
+            EmbedderMsg::EventDelivered((&event).into()),
+        ));
+
+        if let Err(e) = pipeline.event_loop.send(ConstellationControlMsg::SendEvent(
+            destination_pipeline_id,
+            event,
+        )) {
             self.handle_send_error(destination_pipeline_id, e);
         }
     }

components/shared/embedder/lib.rs

@@ -208,6 +208,21 @@ pub enum EmbedderMsg {
     OnDevtoolsStarted(Result<u16, ()>, String),
     /// Compositing done, but external code needs to present.
     ReadyToPresent,
+    /// The given event was delivered to a pipeline in the given browser.
+    EventDelivered(CompositorEventVariant),
+}
+
+/// The variant of CompositorEvent that was delivered to a pipeline.
+#[derive(Debug, Deserialize, Serialize)]
+pub enum CompositorEventVariant {
+    ResizeEvent,
+    MouseButtonEvent,
+    MouseMoveEvent,
+    TouchEvent,
+    WheelEvent,
+    KeyboardEvent,
+    CompositionEvent,
+    IMEDismissedEvent,
 }
 
 impl Debug for EmbedderMsg {
@@ -245,6 +260,7 @@ impl Debug for EmbedderMsg {
             EmbedderMsg::OnDevtoolsStarted(..) => write!(f, "OnDevtoolsStarted"),
             EmbedderMsg::ShowContextMenu(..) => write!(f, "ShowContextMenu"),
             EmbedderMsg::ReadyToPresent => write!(f, "ReadyToPresent"),
+            EmbedderMsg::EventDelivered(..) => write!(f, "HitTestedEvent"),
         }
     }
 }

components/shared/script/lib.rs

@@ -27,7 +27,7 @@ use canvas_traits::webgl::WebGLPipeline;
 use compositor::ScrollTreeNodeId;
 use crossbeam_channel::{Receiver, RecvTimeoutError, Sender};
 use devtools_traits::{DevtoolScriptControlMsg, ScriptToDevtoolsControlMsg, WorkerId};
-use embedder_traits::Cursor;
+use embedder_traits::{CompositorEventVariant, Cursor};
 use euclid::default::Point2D;
 use euclid::{Length, Rect, Scale, Size2D, UnknownUnit, Vector2D};
 use gfx_traits::Epoch;
@@ -571,6 +571,21 @@ pub enum CompositorEvent {
     IMEDismissedEvent,
 }
 
+impl From<&CompositorEvent> for CompositorEventVariant {
+    fn from(value: &CompositorEvent) -> Self {
+        match value {
+            CompositorEvent::ResizeEvent(..) => CompositorEventVariant::ResizeEvent,
+            CompositorEvent::MouseButtonEvent(..) => CompositorEventVariant::MouseButtonEvent,
+            CompositorEvent::MouseMoveEvent(..) => CompositorEventVariant::MouseMoveEvent,
+            CompositorEvent::TouchEvent(..) => CompositorEventVariant::TouchEvent,
+            CompositorEvent::WheelEvent(..) => CompositorEventVariant::WheelEvent,
+            CompositorEvent::KeyboardEvent(..) => CompositorEventVariant::KeyboardEvent,
+            CompositorEvent::CompositionEvent(..) => CompositorEventVariant::CompositionEvent,
+            CompositorEvent::IMEDismissedEvent => CompositorEventVariant::IMEDismissedEvent,
+        }
+    }
+}
+
 /// Requests a TimerEvent-Message be sent after the given duration.
 #[derive(Debug, Deserialize, Serialize)]
 pub struct TimerEventRequest(

ports/libsimpleservo/api/src/lib.rs

@@ -799,7 +799,8 @@ impl ServoGlue {
                 EmbedderMsg::HeadParsed |
                 EmbedderMsg::SetFullscreenState(..) |
                 EmbedderMsg::ReadyToPresent |
-                EmbedderMsg::ReportProfile(..) => {},
+                EmbedderMsg::ReportProfile(..) |
+                EmbedderMsg::EventDelivered(..) => {},
             }
         }
         Ok(())

ports/servoshell/browser.rs

@@ -14,8 +14,8 @@ use keyboard_types::{Key, KeyboardEvent, Modifiers, ShortcutMatcher};
 use log::{debug, error, info, trace, warn};
 use servo::compositing::windowing::{EmbedderEvent, WebRenderDebugOption};
 use servo::embedder_traits::{
-    ContextMenuResult, EmbedderMsg, FilterPattern, PermissionPrompt, PermissionRequest,
-    PromptDefinition, PromptOrigin, PromptResult,
+    CompositorEventVariant, ContextMenuResult, EmbedderMsg, FilterPattern, PermissionPrompt,
+    PermissionRequest, PromptDefinition, PromptOrigin, PromptResult,
 };
 use servo::msg::constellation_msg::{TopLevelBrowsingContextId as BrowserId, TraversalDirection};
 use servo::script_traits::TouchEventType;
@@ -545,6 +545,13 @@ where
                 EmbedderMsg::ReadyToPresent => {
                     need_present = true;
                 },
+                EmbedderMsg::EventDelivered(event) => match (browser_id, event) {
+                    (Some(browser_id), CompositorEventVariant::MouseButtonEvent) => {
+                        // TODO Focus browser and/or raise to top if needed.
+                        trace!("{}: Got a mouse button event", browser_id);
+                    },
+                    (_, _) => {},
+                },
             }
         }