Fixing box with corner radius doesn't have shadow

change/react-native-windows-7ee31594-04e3-459a-8d85-f305644d691c.json

@@ -0,0 +1,7 @@
+{
+  "comment": "adding fix for shadow in rounded box",
+  "type": "prerelease",
+  "packageName": "react-native-windows",
+  "email": "protikbiswas@microsoft.com",
+  "dependentChangeType": "patch"
+}

vnext/Microsoft.ReactNative/CompositionSwitcher.idl

@@ -45,9 +45,16 @@ enum SnapPointsAlignment {
   void Opacity(Single value);
   void BlurRadius(Single value);
   void Color(Windows.UI.Color value);
+  void Mask(IBrush mask);
+  void SourcePolicy(CompositionDropShadowSourcePolicy policy);
 }
 
-    [webhosthidden][experimental] interface IVisual {
+[webhosthidden][experimental] enum CompositionDropShadowSourcePolicy {
+  Default = 0,
+  InheritedOnly = 1
+};
+
+[webhosthidden][experimental] interface IVisual {
   void InsertAt(IVisual visual, Int32 index);
   void Remove(IVisual visual);
   IVisual GetAt(UInt32 index);

vnext/Microsoft.ReactNative/Fabric/Composition/CompositionContextHelper.cpp

@@ -50,6 +50,7 @@ struct CompositionTypeTraits<WindowsTypeTag> {
   using CompositionStretch = winrt::Windows::UI::Composition::CompositionStretch;
   using CompositionStrokeCap = winrt::Windows::UI::Composition::CompositionStrokeCap;
   using CompositionSurfaceBrush = winrt::Windows::UI::Composition::CompositionSurfaceBrush;
+  using CompositionDropShadowSourcePolicy = winrt::Windows::UI::Composition::CompositionDropShadowSourcePolicy;
   using Compositor = winrt::Windows::UI::Composition::Compositor;
   using ContainerVisual = winrt::Windows::UI::Composition::ContainerVisual;
   using CubicBezierEasingFunction = winrt::Windows::UI::Composition::CubicBezierEasingFunction;
@@ -122,6 +123,7 @@ struct CompositionTypeTraits<MicrosoftTypeTag> {
   using CompositionStretch = winrt::Microsoft::UI::Composition::CompositionStretch;
   using CompositionStrokeCap = winrt::Microsoft::UI::Composition::CompositionStrokeCap;
   using CompositionSurfaceBrush = winrt::Microsoft::UI::Composition::CompositionSurfaceBrush;
+  using CompositionDropShadowSourcePolicy = winrt::Microsoft::UI::Composition::CompositionDropShadowSourcePolicy;
   using Compositor = winrt::Microsoft::UI::Composition::Compositor;
   using ContainerVisual = winrt::Microsoft::UI::Composition::ContainerVisual;
   using CubicBezierEasingFunction = winrt::Microsoft::UI::Composition::CubicBezierEasingFunction;
@@ -218,6 +220,19 @@ struct CompDropShadow : public winrt::implements<
     m_shadow.Color(color);
   }
 
+  void Mask(winrt::Microsoft::ReactNative::Composition::Experimental::IBrush const &mask) noexcept {
+    if (mask) {
+      m_shadow.Mask(mask.as<typename TTypeRedirects::IInnerCompositionBrush>()->InnerBrush());
+    } else {
+      m_shadow.Mask(nullptr);
+    }
+  }
+
+  void SourcePolicy(
+      winrt::Microsoft::ReactNative::Composition::Experimental::CompositionDropShadowSourcePolicy policy) noexcept {
+    m_shadow.SourcePolicy(static_cast<typename TTypeRedirects::CompositionDropShadowSourcePolicy>(policy));
+  }
+
  private:
   typename TTypeRedirects::DropShadow m_shadow;
 };

vnext/Microsoft.ReactNative/Fabric/Composition/CompositionViewComponentView.cpp

@@ -709,9 +709,86 @@ void ComponentView::applyShadowProps(const facebook::react::ViewProps &viewProps
       shadow.Color(theme()->Color(*viewProps.shadowColor));
   }
 
-  // Apply shadow to OuterVisual (not Visual) because Visual may have a rounded-corner clip
-  // from updateClippingPath, which would clip the shadow. OuterVisual is not clipped.
-  OuterVisual().as<winrt::Microsoft::ReactNative::Composition::Experimental::ISpriteVisual>().Shadow(shadow);
+  // Check if any border radius is set
+  auto borderMetrics = BorderPrimitive::resolveAndAlignBorderMetrics(m_layoutMetrics, viewProps);
+  bool hasBorderRadius = borderMetrics.borderRadii.topLeft.horizontal != 0 ||
+      borderMetrics.borderRadii.topRight.horizontal != 0 || borderMetrics.borderRadii.bottomLeft.horizontal != 0 ||
+      borderMetrics.borderRadii.bottomRight.horizontal != 0 || borderMetrics.borderRadii.topLeft.vertical != 0 ||
+      borderMetrics.borderRadii.topRight.vertical != 0 || borderMetrics.borderRadii.bottomLeft.vertical != 0 ||
+      borderMetrics.borderRadii.bottomRight.vertical != 0;
+
+  if (hasBorderRadius) {
+    // When borderRadius is set, we need to create a shadow mask that follows the rounded rectangle shape.
+    // Use CompositionVisualSurface to capture the clipped visual's appearance as the shadow mask.
+    bool maskSet = false;
+
+    // Try Microsoft (WinUI3) Composition first
+    auto msCompositor =
+        winrt::Microsoft::ReactNative::Composition::Experimental::MicrosoftCompositionContextHelper::InnerCompositor(
+            m_compContext);
+    if (msCompositor) {
+      auto innerVisual =
+          winrt::Microsoft::ReactNative::Composition::Experimental::MicrosoftCompositionContextHelper::InnerVisual(
+              Visual());
+      if (innerVisual) {
+        // Create a VisualSurface that captures the visual (with its clip applied)
+        auto visualSurface = msCompositor.CreateVisualSurface();
+        visualSurface.SourceVisual(innerVisual);
+        visualSurface.SourceSize(
+            {m_layoutMetrics.frame.size.width * m_layoutMetrics.pointScaleFactor,
+             m_layoutMetrics.frame.size.height * m_layoutMetrics.pointScaleFactor});
+
+        // Create a brush from the visual surface to use as shadow mask
+        auto maskBrush = msCompositor.CreateSurfaceBrush(visualSurface);
+        maskBrush.Stretch(winrt::Microsoft::UI::Composition::CompositionStretch::Fill);
+
+        // Get the inner shadow and set the mask
+        auto innerShadow = winrt::Microsoft::ReactNative::Composition::Experimental::MicrosoftCompositionContextHelper::
+            InnerDropShadow(shadow);
+        if (innerShadow) {
+          innerShadow.Mask(maskBrush);
+          maskSet = true;
+        }
+      }
+    }
+
+    // Fallback to System (Windows.UI) Composition if Microsoft Composition is not available
+    if (!maskSet) {
+      auto sysCompositor =
+          winrt::Microsoft::ReactNative::Composition::Experimental::SystemCompositionContextHelper::InnerCompositor(
+              m_compContext);
+      if (sysCompositor) {
+        auto innerVisual =
+            winrt::Microsoft::ReactNative::Composition::Experimental::SystemCompositionContextHelper::InnerVisual(
+                Visual());
+        if (innerVisual) {
+          auto visualSurface = sysCompositor.CreateVisualSurface();
+          visualSurface.SourceVisual(innerVisual);
+          visualSurface.SourceSize(
+              {m_layoutMetrics.frame.size.width * m_layoutMetrics.pointScaleFactor,
+               m_layoutMetrics.frame.size.height * m_layoutMetrics.pointScaleFactor});
+
+          auto maskBrush = sysCompositor.CreateSurfaceBrush(visualSurface);
+          maskBrush.Stretch(winrt::Windows::UI::Composition::CompositionStretch::Fill);
+
+          auto innerShadow =
+              winrt::Microsoft::ReactNative::Composition::Experimental::SystemCompositionContextHelper::InnerDropShadow(
+                  shadow);
+          if (innerShadow) {
+            innerShadow.Mask(maskBrush);
+          }
+        }
+      }
+    }
+
+    // Apply shadow to OuterVisual (which is not clipped) so the shadow can extend beyond the clip
+    OuterVisual().as<winrt::Microsoft::ReactNative::Composition::Experimental::ISpriteVisual>().Shadow(shadow);
+    Visual().as<winrt::Microsoft::ReactNative::Composition::Experimental::ISpriteVisual>().Shadow(nullptr);
+  } else {
+    // No border radius - apply shadow directly to Visual (original behavior)
+    Visual().as<winrt::Microsoft::ReactNative::Composition::Experimental::ISpriteVisual>().Shadow(shadow);
+    OuterVisual().as<winrt::Microsoft::ReactNative::Composition::Experimental::ISpriteVisual>().Shadow(nullptr);
+  }
 }
 
 void ComponentView::updateTransformProps(