From 1b2729c92ebc0abf2b7e2400142a575fea4cb279 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rub=C3=A9n=20Norte?= <rubennorte@meta.com>
Date: Thu, 10 Apr 2025 09:12:38 -0700
Subject: [PATCH] Define continuous and idle priority for raw events and expose
 them to React via nativeFabricUIManager

Summary:
Changelog: [internal]

This defines 2 new priorities in Fabric, matching the definitions in React:
* Continuous
* Idle

They're exposed to React via 2 new properties in `nativeFabricUIManager`: `unstable_ContinuousEventPriority` and `unstable_IdleEventPriority`.

It also adds the mapping from the raw event priorities to the Fabric event priorities.

This change doesn't have any effect at the moment. For these to come into effect, we need to:
1. Fix the mapping between Fabric priorities and React priorities in the React repository. See https://github.com/facebook/react/pull/32847
2. Enable the `fixMappingOfEventPrioritiesBetweenFabricAndReact` feature flag.

Differential Revision: D72791968
---
 .../src/main/jni/react/fabric/FabricUIManagerBinding.cpp  | 1 -
 .../react/renderer/core/EventQueueProcessor.cpp           | 2 ++
 .../ReactCommon/react/renderer/core/RawEvent.h            | 8 +++++++-
 .../ReactCommon/react/renderer/core/ReactEventPriority.h  | 5 +++++
 .../react/renderer/uimanager/UIManagerBinding.cpp         | 8 ++++++++
 5 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/packages/react-native/ReactAndroid/src/main/jni/react/fabric/FabricUIManagerBinding.cpp b/packages/react-native/ReactAndroid/src/main/jni/react/fabric/FabricUIManagerBinding.cpp
index b3813b0a0ed7..5a00be8aee2b 100644
--- a/packages/react-native/ReactAndroid/src/main/jni/react/fabric/FabricUIManagerBinding.cpp
+++ b/packages/react-native/ReactAndroid/src/main/jni/react/fabric/FabricUIManagerBinding.cpp
@@ -10,7 +10,6 @@
 #include "AndroidEventBeat.h"
 #include "ComponentFactory.h"
 #include "EventBeatManager.h"
-#include "EventEmitterWrapper.h"
 #include "FabricMountingManager.h"
 
 #include <cxxreact/TraceSection.h>
diff --git a/packages/react-native/ReactCommon/react/renderer/core/EventQueueProcessor.cpp b/packages/react-native/ReactCommon/react/renderer/core/EventQueueProcessor.cpp
index ce1485b3ac11..7d268e2c2048 100644
--- a/packages/react-native/ReactCommon/react/renderer/core/EventQueueProcessor.cpp
+++ b/packages/react-native/ReactCommon/react/renderer/core/EventQueueProcessor.cpp
@@ -55,6 +55,8 @@ void EventQueueProcessor::flushEvents(
             return ReactEventPriority::Discrete;
           case RawEvent::Category::Continuous:
             return ReactEventPriority::Continuous;
+          case RawEvent::Category::Idle:
+            return ReactEventPriority::Idle;
           case RawEvent::Category::Unspecified:
             return hasContinuousEventStarted_ ? ReactEventPriority::Continuous
                                               : ReactEventPriority::Default;
diff --git a/packages/react-native/ReactCommon/react/renderer/core/RawEvent.h b/packages/react-native/ReactCommon/react/renderer/core/RawEvent.h
index c79aca59aa99..e701c12d8698 100644
--- a/packages/react-native/ReactCommon/react/renderer/core/RawEvent.h
+++ b/packages/react-native/ReactCommon/react/renderer/core/RawEvent.h
@@ -56,7 +56,13 @@ struct RawEvent {
      * Forces continuous type for the event. Regardless if continuous event
      * isn't ongoing.
      */
-    Continuous = 4
+    Continuous = 4,
+
+    /*
+     * Priority for events that can be processed in idle times or in the
+     * background.
+     */
+    Idle = 5,
   };
 
   RawEvent(
diff --git a/packages/react-native/ReactCommon/react/renderer/core/ReactEventPriority.h b/packages/react-native/ReactCommon/react/renderer/core/ReactEventPriority.h
index 741084fe67b5..f85a9a01b7be 100644
--- a/packages/react-native/ReactCommon/react/renderer/core/ReactEventPriority.h
+++ b/packages/react-native/ReactCommon/react/renderer/core/ReactEventPriority.h
@@ -30,6 +30,11 @@ enum class ReactEventPriority {
    * scrolling.
    */
   Continuous,
+
+  /*
+   * Other events that can be processed in the background.
+   */
+  Idle,
 };
 
 static constexpr std::underlying_type<ReactEventPriority>::type serialize(
diff --git a/packages/react-native/ReactCommon/react/renderer/uimanager/UIManagerBinding.cpp b/packages/react-native/ReactCommon/react/renderer/uimanager/UIManagerBinding.cpp
index dddcd52e2de4..c5baaf76cfe4 100644
--- a/packages/react-native/ReactCommon/react/renderer/uimanager/UIManagerBinding.cpp
+++ b/packages/react-native/ReactCommon/react/renderer/uimanager/UIManagerBinding.cpp
@@ -747,6 +747,14 @@ jsi::Value UIManagerBinding::get(
     return {serialize(ReactEventPriority::Discrete)};
   }
 
+  if (methodName == "unstable_ContinuousEventPriority") {
+    return {serialize(ReactEventPriority::Continuous)};
+  }
+
+  if (methodName == "unstable_IdleEventPriority") {
+    return {serialize(ReactEventPriority::Idle)};
+  }
+
   if (methodName == "findShadowNodeByTag_DEPRECATED") {
     auto paramCount = 1;
     return jsi::Function::createFromHostFunction(