Changed Mica dark/light based on theme

samples/ControlCatalog/MainView.xaml

@@ -226,8 +226,7 @@
                 <WindowTransparencyLevel>Transparent</WindowTransparencyLevel>
                 <WindowTransparencyLevel>Blur</WindowTransparencyLevel>
                 <WindowTransparencyLevel>AcrylicBlur</WindowTransparencyLevel>
-                <WindowTransparencyLevel>MicaLight</WindowTransparencyLevel>
-                <WindowTransparencyLevel>MicaDark</WindowTransparencyLevel>
+                <WindowTransparencyLevel>Mica</WindowTransparencyLevel>
               </ComboBox.Items>
             </ComboBox>
             <ComboBox x:Name="FlowDirection"

src/Avalonia.Controls/WindowTransparencyLevel.cs

@@ -33,15 +33,10 @@ public readonly record struct WindowTransparencyLevel
     public static WindowTransparencyLevel AcrylicBlur { get; } = new(nameof(AcrylicBlur));
 
     /// <summary>
-    /// The window background is based on desktop wallpaper tint with a light blur. This will only work on Windows 11 
+    /// The window background is based on desktop wallpaper tint with a blur. This will only work on Windows 11 
     /// </summary>
-    public static WindowTransparencyLevel MicaLight { get; } = new(nameof(MicaLight));
+    public static WindowTransparencyLevel Mica { get; } = new(nameof(Mica));
     
-    /// <summary>
-    /// The window background is based on desktop wallpaper tint with a dark blur. This will only work on Windows 11
-    /// </summary>
-    public static WindowTransparencyLevel MicaDark { get; } = new(nameof(MicaDark));
-
     public override string ToString()
     {
         return _value;

src/Windows/Avalonia.Win32/WinRT/Composition/WinUiCompositedWindow.cs

@@ -76,9 +76,6 @@ internal class WinUiCompositedWindow : IDisposable
         using var compositionBrush = _surfaceBrush.QueryInterface<ICompositionBrush>();
         spriteVisual.SetBrush(compositionBrush);
         _target.SetRoot(containerVisual);
-        
-        
-        
     }
 
     public void SetSurface(ICompositionSurface surface) => _surfaceBrush.SetSurface(surface);

src/Windows/Avalonia.Win32/WindowImpl.cs

@@ -106,6 +106,7 @@ namespace Avalonia.Win32
         private static POINTER_PEN_INFO[]? s_historyPenInfos;
         private static POINTER_INFO[]? s_historyInfos;
         private static MOUSEMOVEPOINT[]? s_mouseHistoryInfos;
+        private PlatformThemeVariant _currentThemeVariant;
 
         public WindowImpl()
         {
@@ -374,10 +375,8 @@ namespace Avalonia.Win32
                     SetTransparencyBlur(windowsVersion);
                 else if (level == WindowTransparencyLevel.AcrylicBlur)
                     SetTransparencyAcrylicBlur(windowsVersion);
-                else if (level == WindowTransparencyLevel.MicaLight)
-                    SetTransparencyMicaLight(windowsVersion);
-                else if (level == WindowTransparencyLevel.MicaDark)
-                    SetTransparencyMicaDark(windowsVersion);
+                else if (level == WindowTransparencyLevel.Mica)
+                    SetTransparencyMica(windowsVersion);
 
                 TransparencyLevel = level;
                 return;
@@ -420,7 +419,7 @@ namespace Avalonia.Win32
                 return windowsVersion >= WinUiCompositionShared.MinAcrylicVersion;
 
             // Mica is supported on Windows >= 10.0.22000.
-            if (level == WindowTransparencyLevel.MicaLight || level == WindowTransparencyLevel.MicaDark)
+            if (level == WindowTransparencyLevel.Mica)
                 return windowsVersion >= WinUiCompositionShared.MinHostBackdropVersion;
 
             return false;
@@ -469,24 +468,19 @@ namespace Avalonia.Win32
             _blurHost?.SetBlur(BlurEffect.Acrylic);
         }
 
-        private void SetTransparencyMicaLight(Version windowsVersion)
+        private void SetTransparencyMica(Version windowsVersion)
         {
             // Mica only supported with composition on Windows >= 10.0.22000.
             if (!_isUsingComposition || windowsVersion < WinUiCompositionShared.MinHostBackdropVersion)
                 return;
 
             SetUseHostBackdropBrush(false);
-            _blurHost?.SetBlur(BlurEffect.MicaLight);
-        }      
-        
-        private void SetTransparencyMicaDark(Version windowsVersion)
-        {
-            // Mica only supported with composition on Windows >= 10.0.22000.
-            if (!_isUsingComposition || windowsVersion < WinUiCompositionShared.MinHostBackdropVersion)
-                return;
-
-            SetUseHostBackdropBrush(false);
-            _blurHost?.SetBlur(BlurEffect.MicaDark);
+            _blurHost?.SetBlur(_currentThemeVariant switch
+            {
+                PlatformThemeVariant.Light => BlurEffect.MicaLight,
+                PlatformThemeVariant.Dark => BlurEffect.MicaDark,
+                _ => throw new ArgumentOutOfRangeException()
+            });
         }
 
         private void SetAccentState(AccentState state)
@@ -790,6 +784,7 @@ namespace Avalonia.Win32
 
         public unsafe void SetFrameThemeVariant(PlatformThemeVariant themeVariant)
         {
+            _currentThemeVariant = themeVariant;
             if (Win32Platform.WindowsVersion.Build >= 22000)
             {
                 var pvUseBackdropBrush = themeVariant == PlatformThemeVariant.Dark ? 1 : 0;
@@ -798,6 +793,10 @@ namespace Avalonia.Win32
                     (int)DwmWindowAttribute.DWMWA_USE_IMMERSIVE_DARK_MODE,
                     &pvUseBackdropBrush,
                     sizeof(int));
+                if (TransparencyLevel == WindowTransparencyLevel.Mica)
+                {
+                    SetTransparencyMica(Win32Platform.WindowsVersion);
+                }
             }
         }