Create synchronous method to get bounding client rect

Summary: Changelog: [internal] Added internal method in Fabric to synchronously get layout information

Reviewed By: sammy-SC

Differential Revision: D43080208

fbshipit-source-id: 8af9fe8ef9dbfe37c4b70101cc13e12905ee5b69

ReactCommon/react/renderer/uimanager/UIManagerBinding.cpp

@@ -620,7 +620,7 @@ jsi::Value UIManagerBinding::get(
               *shadowNodeFromValue(runtime, arguments[0]),
               nullptr,
               {/* .includeTransform = */ true,
-               /* includeViewportOffset = */ true});
+               /* .includeViewportOffset = */ true});
 
           auto onSuccessFunction =
               arguments[1].getObject(runtime).getFunction(runtime);
@@ -641,6 +641,40 @@ jsi::Value UIManagerBinding::get(
         });
   }
 
+  if (methodName == "getBoundingClientRect") {
+    // This is similar to `measureInWindow`, except it's explicitly synchronous
+    // (returns the result instead of passing it to a callback).
+    // The behavior is similar to `Element.prototype.getBoundingClientRect` from
+    // Web.
+    return jsi::Function::createFromHostFunction(
+        runtime,
+        name,
+        1,
+        [uiManager](
+            jsi::Runtime &runtime,
+            jsi::Value const & /*thisValue*/,
+            jsi::Value const *arguments,
+            size_t /*count*/) noexcept -> jsi::Value {
+          auto layoutMetrics = uiManager->getRelativeLayoutMetrics(
+              *shadowNodeFromValue(runtime, arguments[0]),
+              nullptr,
+              {/* .includeTransform = */ true,
+               /* .includeViewportOffset = */ true});
+
+          if (layoutMetrics == EmptyLayoutMetrics) {
+            return jsi::Value::undefined();
+          }
+
+          auto frame = layoutMetrics.frame;
+          return jsi::Array::createWithElements(
+              runtime,
+              jsi::Value{runtime, (double)frame.origin.x},
+              jsi::Value{runtime, (double)frame.origin.y},
+              jsi::Value{runtime, (double)frame.size.width},
+              jsi::Value{runtime, (double)frame.size.height});
+        });
+  }
+
   if (methodName == "sendAccessibilityEvent") {
     return jsi::Function::createFromHostFunction(
         runtime,