fix: measureInWindow calculations for Modal with formSheet presentation

packages/react-native/React/Fabric/Mounting/ComponentViews/Modal/RCTModalHostViewComponentView.mm

@@ -256,7 +256,16 @@ - (void)boundsDidChange:(CGRect)newBounds
   }
 
   if (_state != nullptr) {
-    auto newState = ModalHostViewState{RCTSizeFromCGSize(newBounds.size)};
+    CGPoint viewportOffset = CGPointZero;
+    UIView *modalView = _viewController.view;
+    if (modalView && modalView.window) {
+      CGRect frameInWindow = [modalView convertRect:modalView.bounds toView:nil];
+      viewportOffset = frameInWindow.origin;
+    }
+    auto newState = ModalHostViewState{
+      RCTSizeFromCGSize(newBounds.size),
+      facebook::react::Point{(Float)viewportOffset.x, (Float)viewportOffset.y}
+    };
     _state->updateState(std::move(newState));
   }
 }

packages/react-native/ReactCommon/react/renderer/components/modal/ModalHostViewShadowNode.cpp

@@ -14,4 +14,9 @@ namespace facebook::react {
 
 extern const char ModalHostViewComponentName[] = "ModalHostView";
 
+Transform ModalHostViewShadowNode::getTransform() const {
+  auto viewportOffset = getStateData().viewportOffset;
+  return Transform::Translate(viewportOffset.x, viewportOffset.y, 0);
+}
+
 } // namespace facebook::react

packages/react-native/ReactCommon/react/renderer/components/modal/ModalHostViewShadowNode.h

@@ -36,6 +36,8 @@ class ModalHostViewShadowNode final : public ConcreteViewShadowNode<
     traits.set(ShadowNodeTraits::Trait::Unstable_uncullableView);
     return traits;
   }
+
+  Transform getTransform() const override;
 };
 
 } // namespace facebook::react

packages/react-native/ReactCommon/react/renderer/components/modal/ModalHostViewState.cpp

@@ -12,7 +12,9 @@ namespace facebook::react {
 #ifdef RN_SERIALIZABLE_STATE
 folly::dynamic ModalHostViewState::getDynamic() const {
   return folly::dynamic::object("screenWidth", screenSize.width)(
-      "screenHeight", screenSize.height);
+      "screenHeight", screenSize.height)(
+      "viewportOffsetX", viewportOffset.x)(
+      "viewportOffsetY", viewportOffset.y);
 }
 #endif
 

packages/react-native/ReactCommon/react/renderer/components/modal/ModalHostViewState.h

@@ -26,15 +26,21 @@ class ModalHostViewState final {
 
   ModalHostViewState() : screenSize(ModalHostViewScreenSize()) {}
   ModalHostViewState(Size screenSize_) : screenSize(screenSize_) {};
+  ModalHostViewState(Size screenSize_, Point viewportOffset_)
+      : screenSize(screenSize_), viewportOffset(viewportOffset_) {};
 
 #ifdef RN_SERIALIZABLE_STATE
   ModalHostViewState(const ModalHostViewState &previousState, folly::dynamic data)
       : screenSize(
-            Size{.width = (Float)data["screenWidth"].getDouble(), .height = (Float)data["screenHeight"].getDouble()}) {
+            Size{.width = (Float)data["screenWidth"].getDouble(), .height = (Float)data["screenHeight"].getDouble()}),
+        viewportOffset(
+            Point{.x = data.count("viewportOffsetX") ? (Float)data["viewportOffsetX"].getDouble() : 0.0f,
+                  .y = data.count("viewportOffsetY") ? (Float)data["viewportOffsetY"].getDouble() : 0.0f}) {
         };
 #endif
 
   const Size screenSize{};
+  const Point viewportOffset{};
 
 #ifdef RN_SERIALIZABLE_STATE
   folly::dynamic getDynamic() const;