Fix dropShadow not creating stacking context (#46143)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/46143

Before `drop-shadow` was not creating a stacking context causing its children to get flattened and not receive the shadow effect.

This was due to incorrect parsing on C++. We didn't notice since we don't support `drop-shadow` on iOS and Android gets the parsed prop directly

Changelog: [Internal]

Reviewed By: NickGerleman, joevilches

Differential Revision: D61617699

fbshipit-source-id: a8bfbb0043fcd2b2867923eb937a6be8e9004f13

packages/react-native/React/Fabric/Mounting/ComponentViews/View/RCTViewComponentView.mm

@@ -844,10 +844,12 @@ static RCTBorderStyle RCTBorderStyleFromBorderStyle(BorderStyle borderStyle)
   if (!_props->filter.empty()) {
     float multiplicativeBrightness = 1;
     for (const auto &primitive : _props->filter) {
-      if (primitive.type == FilterType::Brightness) {
-        multiplicativeBrightness *= primitive.amount;
-      } else if (primitive.type == FilterType::Opacity) {
-        self.layer.opacity *= primitive.amount;
+      if (std::holds_alternative<Float>(primitive.parameters)) {
+        if (primitive.type == FilterType::Brightness) {
+          multiplicativeBrightness *= std::get<Float>(primitive.parameters);
+        } else if (primitive.type == FilterType::Opacity) {
+          self.layer.opacity *= std::get<Float>(primitive.parameters);
+        }
       }
     }
 

packages/react-native/ReactCommon/react/renderer/components/view/conversions.h

@@ -1032,7 +1032,7 @@ inline void fromRawValue(
   result = boxShadows;
 }
 inline void fromRawValue(
-    const PropsParserContext& /*context*/,
+    const PropsParserContext& context,
     const RawValue& value,
     std::vector<FilterFunction>& result) {
   react_native_expect(value.hasType<std::vector<RawValue>>());
@@ -1054,14 +1054,69 @@ inline void fromRawValue(
       return;
     }
 
-    auto rawFilterPrimitiveMap =
+    auto rawFilterFunction =
         static_cast<std::unordered_map<std::string, RawValue>>(
             rawFilterPrimitive);
     FilterFunction filterFunction{};
     try {
       filterFunction.type =
-          filterTypeFromString(rawFilterPrimitiveMap.begin()->first);
-      filterFunction.amount = (float)rawFilterPrimitiveMap.begin()->second;
+          filterTypeFromString(rawFilterFunction.begin()->first);
+      if (filterFunction.type == FilterType::DropShadow) {
+        auto rawDropShadow =
+            static_cast<std::unordered_map<std::string, RawValue>>(
+                rawFilterFunction.begin()->second);
+        DropShadowParams dropShadowParams{};
+
+        auto offsetX = rawDropShadow.find("offsetX");
+        react_native_expect(offsetX != rawDropShadow.end());
+        if (offsetX == rawDropShadow.end()) {
+          result = {};
+          return;
+        }
+
+        react_native_expect(offsetX->second.hasType<Float>());
+        if (!offsetX->second.hasType<Float>()) {
+          result = {};
+          return;
+        }
+        dropShadowParams.offsetX = (Float)offsetX->second;
+
+        auto offsetY = rawDropShadow.find("offsetY");
+        react_native_expect(offsetY != rawDropShadow.end());
+        if (offsetY == rawDropShadow.end()) {
+          result = {};
+          return;
+        }
+        react_native_expect(offsetY->second.hasType<Float>());
+        if (!offsetY->second.hasType<Float>()) {
+          result = {};
+          return;
+        }
+        dropShadowParams.offsetY = (Float)offsetY->second;
+
+        auto standardDeviation = rawDropShadow.find("standardDeviation");
+        if (standardDeviation != rawDropShadow.end()) {
+          react_native_expect(standardDeviation->second.hasType<Float>());
+          if (!standardDeviation->second.hasType<Float>()) {
+            result = {};
+            return;
+          }
+          dropShadowParams.standardDeviation = (Float)standardDeviation->second;
+        }
+
+        auto color = rawDropShadow.find("color");
+        if (color != rawDropShadow.end()) {
+          fromRawValue(
+              context.contextContainer,
+              context.surfaceId,
+              color->second,
+              dropShadowParams.color);
+        }
+
+        filterFunction.parameters = dropShadowParams;
+      } else {
+        filterFunction.parameters = (float)rawFilterFunction.begin()->second;
+      }
       filter.push_back(std::move(filterFunction));
     } catch (const std::exception& e) {
       LOG(ERROR) << "Could not parse FilterFunction: " << e.what();

packages/react-native/ReactCommon/react/renderer/graphics/Filter.h

@@ -7,10 +7,12 @@
 
 #pragma once
 
+#include <react/renderer/graphics/Color.h>
 #include <react/renderer/graphics/Float.h>
 
 #include <string>
 #include <string_view>
+#include <variant>
 #include <vector>
 
 namespace facebook::react {
@@ -28,11 +30,20 @@ enum class FilterType {
   DropShadow
 };
 
+struct DropShadowParams {
+  bool operator==(const DropShadowParams& other) const = default;
+
+  Float offsetX{};
+  Float offsetY{};
+  Float standardDeviation{};
+  SharedColor color{};
+};
+
 struct FilterFunction {
   bool operator==(const FilterFunction& other) const = default;
 
-  FilterType type;
-  Float amount;
+  FilterType type{};
+  std::variant<Float, DropShadowParams> parameters{};
 };
 
 inline FilterType filterTypeFromString(std::string_view filterName) {