BridgelessUIManager: Finish findSubviewIn

Summary:
This is an implementation of UIManagerModule.findSubviewIn, based on the [Fabric renderer](https://github.com/facebook/react-fbsource-import/blob/772935f7320f37a14ef06a9616dd43fa090d54a3/compiled-rn/facebook-fbsource/xplat/js/react-native-github/Libraries/Renderer/implementations/ReactFabric-dev.fb.js#L28899-L28953).

UIManager.findSubviewIn(viewTag, point, callback)

The point is relative to viewTag's parent's (0, 0).

Changelog: [Internal]

Reviewed By: sammy-SC

Differential Revision: D52642884

fbshipit-source-id: 775e98d23ff42d41c30644b82f5f67e788df4ee6

Author: RSNara

packages/react-native/Libraries/ReactNative/BridgelessUIManager.js

@@ -336,7 +336,54 @@ const UIManagerJS: UIManagerJSInterface & {[string]: any} = {
       height: number,
     ) => void,
   ): void => {
-    raiseSoftError('findSubviewIn');
+    if (reactTag == null) {
+      console.error(
+        `findSubviewIn() noop: Cannot be called with ${String(
+          reactTag,
+        )} reactTag`,
+      );
+      return;
+    }
+
+    const FabricUIManager = nullthrows(getFabricUIManager());
+    const shadowNode = FabricUIManager.findShadowNodeByTag_DEPRECATED(reactTag);
+
+    if (!shadowNode) {
+      console.error(
+        `findSubviewIn() noop: Cannot find view with reactTag ${reactTag}`,
+      );
+      return;
+    }
+
+    FabricUIManager.findNodeAtPoint(
+      shadowNode,
+      point[0],
+      point[1],
+      function (internalInstanceHandle) {
+        if (internalInstanceHandle == null) {
+          console.error('findSubviewIn(): Cannot find node at point');
+          return;
+        }
+
+        let instanceHandle: Object = internalInstanceHandle;
+        let node = instanceHandle.stateNode.node;
+
+        if (!node) {
+          console.error('findSubviewIn(): Cannot find node at point');
+          return;
+        }
+
+        let nativeViewTag = (instanceHandle.stateNode.canonical
+          .nativeTag: number);
+
+        FabricUIManager.measure(
+          node,
+          function (x, y, width, height, pageX, pageY) {
+            callback(nativeViewTag, pageX, pageY, width, height);
+          },
+        );
+      },
+    );
   },
   viewIsDescendantOf: (
     reactTag: ?number,

packages/react-native/Libraries/ReactNative/FabricUIManager.js

@@ -64,6 +64,12 @@ export interface Spec {
     commandName: string,
     args: Array<mixed>,
   ) => void;
+  +findNodeAtPoint: (
+    node: Node,
+    locationX: number,
+    locationY: number,
+    callback: (instanceHandle: ?InternalInstanceHandle) => void,
+  ) => void;
 
   /**
    * Support methods for the DOM-compatible APIs.

packages/react-native/Libraries/ReactNative/__mocks__/FabricUIManager.js

@@ -292,6 +292,15 @@ const FabricUIManagerMock: IFabricUIManagerMock = {
 
   findShadowNodeByTag_DEPRECATED: jest.fn((reactTag: number): ?Node => {}),
 
+  findNodeAtPoint: jest.fn(
+    (
+      node: Node,
+      locationX: number,
+      locationY: number,
+      callback: (instanceHandle: ?InternalInstanceHandle) => void,
+    ): void => {},
+  ),
+
   getBoundingClientRect: jest.fn(
     (
       node: Node,

packages/react-native/Libraries/__tests__/__snapshots__/public-api-test.js.snap

@@ -6564,6 +6564,12 @@ export interface Spec {
     commandName: string,
     args: Array<mixed>
   ) => void;
+  +findNodeAtPoint: (
+    node: Node,
+    locationX: number,
+    locationY: number,
+    callback: (instanceHandle: ?InternalInstanceHandle) => void
+  ) => void;
   +getParentNode: (node: Node) => ?InternalInstanceHandle;
   +getChildNodes: (node: Node) => $ReadOnlyArray<InternalInstanceHandle>;
   +isConnected: (node: Node) => boolean;