[Draft] Enabling Fluent as default theme using an opt-in and app.config

src/Microsoft.DotNet.Wpf/ApiCompat/Baselines/PresentationFramework-ref.baseline.txt

@@ -50,6 +50,34 @@ CannotChangeAttribute : Attribute 'System.ComponentModel.DesignerSerializationVi
 CannotChangeAttribute : Attribute 'System.Windows.LocalizabilityAttribute' on 'System.Windows.Style.TargetType' changed from '[LocalizabilityAttribute(17)]' in the contract to '[LocalizabilityAttribute(LocalizationCategory.NeverLocalize)]' in the implementation.
 CannotChangeAttribute : Attribute 'System.ComponentModel.DesignerSerializationVisibilityAttribute' on 'System.Windows.Style.Triggers' changed from '[DesignerSerializationVisibilityAttribute(2)]' in the contract to '[DesignerSerializationVisibilityAttribute(DesignerSerializationVisibility.Content)]' in the implementation.
 CannotChangeAttribute : Attribute 'System.AttributeUsageAttribute' on 'System.Windows.StyleTypedPropertyAttribute' changed from '[AttributeUsageAttribute(4, AllowMultiple=true)]' in the contract to '[AttributeUsageAttribute(AttributeTargets.Class, AllowMultiple=true)]' in the implementation.
+MembersMustExist : Member 'public System.Windows.Media.Color System.Windows.SystemColors.AccentColor.get()' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public System.Windows.Media.SolidColorBrush System.Windows.SystemColors.AccentColorBrush.get()' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public System.Windows.ResourceKey System.Windows.SystemColors.AccentColorBrushKey.get()' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public System.Windows.Media.Color System.Windows.SystemColors.AccentColorDark1.get()' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public System.Windows.Media.SolidColorBrush System.Windows.SystemColors.AccentColorDark1Brush.get()' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public System.Windows.ResourceKey System.Windows.SystemColors.AccentColorDark1BrushKey.get()' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public System.Windows.ResourceKey System.Windows.SystemColors.AccentColorDark1Key.get()' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public System.Windows.Media.Color System.Windows.SystemColors.AccentColorDark2.get()' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public System.Windows.Media.SolidColorBrush System.Windows.SystemColors.AccentColorDark2Brush.get()' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public System.Windows.ResourceKey System.Windows.SystemColors.AccentColorDark2BrushKey.get()' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public System.Windows.ResourceKey System.Windows.SystemColors.AccentColorDark2Key.get()' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public System.Windows.Media.Color System.Windows.SystemColors.AccentColorDark3.get()' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public System.Windows.Media.SolidColorBrush System.Windows.SystemColors.AccentColorDark3Brush.get()' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public System.Windows.ResourceKey System.Windows.SystemColors.AccentColorDark3BrushKey.get()' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public System.Windows.ResourceKey System.Windows.SystemColors.AccentColorDark3Key.get()' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public System.Windows.ResourceKey System.Windows.SystemColors.AccentColorKey.get()' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public System.Windows.Media.Color System.Windows.SystemColors.AccentColorLight1.get()' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public System.Windows.Media.SolidColorBrush System.Windows.SystemColors.AccentColorLight1Brush.get()' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public System.Windows.ResourceKey System.Windows.SystemColors.AccentColorLight1BrushKey.get()' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public System.Windows.ResourceKey System.Windows.SystemColors.AccentColorLight1Key.get()' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public System.Windows.Media.Color System.Windows.SystemColors.AccentColorLight2.get()' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public System.Windows.Media.SolidColorBrush System.Windows.SystemColors.AccentColorLight2Brush.get()' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public System.Windows.ResourceKey System.Windows.SystemColors.AccentColorLight2BrushKey.get()' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public System.Windows.ResourceKey System.Windows.SystemColors.AccentColorLight2Key.get()' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public System.Windows.Media.Color System.Windows.SystemColors.AccentColorLight3.get()' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public System.Windows.Media.SolidColorBrush System.Windows.SystemColors.AccentColorLight3Brush.get()' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public System.Windows.ResourceKey System.Windows.SystemColors.AccentColorLight3BrushKey.get()' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public System.Windows.ResourceKey System.Windows.SystemColors.AccentColorLight3Key.get()' does not exist in the implementation but it does exist in the contract.
 CannotChangeAttribute : Attribute 'System.AttributeUsageAttribute' on 'System.Windows.TemplatePartAttribute' changed from '[AttributeUsageAttribute(4, AllowMultiple=true)]' in the contract to '[AttributeUsageAttribute(AttributeTargets.Class, AllowMultiple=true)]' in the implementation.
 CannotChangeAttribute : Attribute 'System.AttributeUsageAttribute' on 'System.Windows.TemplateVisualStateAttribute' changed from '[AttributeUsageAttribute(4, AllowMultiple=true)]' in the contract to '[AttributeUsageAttribute(AttributeTargets.Class, AllowMultiple=true)]' in the implementation.
 CannotChangeAttribute : Attribute 'System.AttributeUsageAttribute' on 'System.Windows.ThemeInfoAttribute' changed from '[AttributeUsageAttribute(1)]' in the contract to '[AttributeUsageAttribute(AttributeTargets.Assembly)]' in the implementation.
@@ -262,4 +290,4 @@ CannotChangeAttribute : Attribute 'System.ComponentModel.DesignerSerializationVi
 CannotChangeAttribute : Attribute 'System.Windows.Markup.DesignerSerializationOptionsAttribute' on 'System.Windows.Markup.XmlAttributeProperties.GetXmlSpace(System.Windows.DependencyObject)' changed from '[DesignerSerializationOptionsAttribute(1)]' in the contract to '[DesignerSerializationOptionsAttribute(DesignerSerializationOptions.SerializeAsAttribute)]' in the implementation.
 CannotChangeAttribute : Attribute 'System.ComponentModel.DesignerSerializationVisibilityAttribute' on 'System.Windows.Media.Animation.Storyboard.GetTarget(System.Windows.DependencyObject)' changed from '[DesignerSerializationVisibilityAttribute(0)]' in the contract to '[DesignerSerializationVisibilityAttribute(DesignerSerializationVisibility.Hidden)]' in the implementation.
 CannotChangeAttribute : Attribute 'System.Windows.LocalizabilityAttribute' on 'System.Windows.Shapes.Shape' changed from '[LocalizabilityAttribute(0, Readability=0)]' in the contract to '[LocalizabilityAttribute(LocalizationCategory.None, Readability=Readability.Unreadable)]' in the implementation.
-Total Issues: 263
+Total Issues: 291

src/Microsoft.DotNet.Wpf/src/PresentationFramework/MS/Internal/FrameworkAppContextSwitches.cs

@@ -142,6 +142,19 @@ public static bool DisableFluentThemeWindowBackdrop
                 return LocalAppContext.GetCachedSwitchValue(DisableFluentThemeWindowBackdropSwitchName, ref _DisableFluentThemeWindowBackdrop);
             }
         }
+
+
+        // Switch to enable Fluent theme in WPF
+        internal const string EnableFluentThemeSwitchName = "Switch.System.Windows.Appearance.EnableFluentTheme";
+        private static int _EnableFluentTheme;
+        public static bool EnableFluentTheme
+        {
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            get
+            {
+                return LocalAppContext.GetCachedSwitchValue(EnableFluentThemeSwitchName, ref _EnableFluentTheme);
+            }
+        }
     }
 
 #pragma warning restore 436

src/Microsoft.DotNet.Wpf/src/PresentationFramework/MS/Win32/UxThemeWrapper.cs

@@ -275,9 +275,9 @@ private static void GetThemeNameAndColor(out string themeName, out string themeC
                     themeName = "Aero2";
                 }
 
+                NameValueCollection appSettings = null;
 #if DEBUG
                 // for debugging, config file can override the theme name
-                NameValueCollection appSettings = null;
                 try
                 {
                     appSettings = ConfigurationManager.AppSettings;
@@ -297,6 +297,38 @@ private static void GetThemeNameAndColor(out string themeName, out string themeC
 #endif
 
                 themeColor = themeColorSB.ToString();
+
+                if (FrameworkAppContextSwitches.EnableFluentTheme)
+                {
+                    themeName = "Fluent";
+                    themeColor = ThemeManager.IsSystemThemeLight() ? "Light" : "Dark";
+
+                    appSettings = null;
+                    try
+                    {
+                        appSettings = ConfigurationManager.AppSettings;
+                    }
+                    catch (ConfigurationErrorsException)
+                    {
+                    }
+
+                    if (appSettings != null)
+                    {
+                        string tc = appSettings["ThemeColorOverride"];
+                        if (!String.IsNullOrEmpty(tc))
+                        {
+                            switch(tc.ToLowerInvariant())
+                            {
+                                case "light":
+                                case "dark":
+                                    themeColor = tc;
+                                    ThemeManager.OverrideThemeColor(themeColor);
+                                    break;
+                            }
+                            themeColor = tc;
+                        }
+                    }
+                }
             }
             else
             {

src/Microsoft.DotNet.Wpf/src/PresentationFramework/System/AppContextDefaultValues.cs

@@ -73,6 +73,8 @@ private static void InitializeNetFxSwitchDefaultsForNetCoreRuntime()
             LocalAppContext.DefineSwitchDefault(FrameworkAppContextSwitches.AppendLocalAssemblyVersionForSourceUriSwitchName, false);
             LocalAppContext.DefineSwitchDefault(FrameworkAppContextSwitches.KeyboardNavigationFromHyperlinkInItemsControlIsNotRelativeToFocusedElementSwitchName, false);
             LocalAppContext.DefineSwitchDefault(FrameworkAppContextSwitches.ItemAutomationPeerKeepsItsItemAliveSwitchName, false);
+
+            LocalAppContext.DefineSwitchDefault(FrameworkAppContextSwitches.EnableFluentThemeSwitchName, true);
             LocalAppContext.DefineSwitchDefault(FrameworkAppContextSwitches.DisableFluentThemeWindowBackdropSwitchName, false);
 
             // UseAdornerForTextboxSelectionRenderingSwitchName is always true, i.e., disabled by default. 

src/Microsoft.DotNet.Wpf/src/PresentationFramework/System/Windows/Appearance/WindowBackdropManager.cs

@@ -133,7 +133,8 @@ private static bool UpdateGlassFrame(IntPtr hwnd, WindowBackdropType backdropTyp
     #region Internal Properties
 
     internal static bool IsBackdropEnabled => _isBackdropEnabled ??= Utility.IsWindows11_22H2OrNewer && 
-                                                                        ThemeManager.IsFluentThemeEnabled &&
+                                                                        (ThemeManager.IsFluentThemeEnabled || 
+                                                                            FrameworkAppContextSwitches.EnableFluentTheme) &&
                                                                         !FrameworkAppContextSwitches.DisableFluentThemeWindowBackdrop;
 
     private static bool? _isBackdropEnabled = null;

src/Microsoft.DotNet.Wpf/src/PresentationFramework/System/Windows/DWMColorization.cs

@@ -22,6 +22,28 @@ internal static Color CurrentApplicationAccentColor
         get { return _currentApplicationAccentColor; }
     }
 
+    static DwmColorization()
+    {
+        UpdateCachedAccentColors();
+    }
+
+
+    #region Accent Colors Properties
+
+    internal static Color AccentColor
+    {
+        get { return _currentApplicationAccentColor; }
+    }
+
+    internal static Color AccentColorLight1 { get; set; }
+    internal static Color AccentColorLight2 { get; set; }
+    internal static Color AccentColorLight3 { get; set; }
+    internal static Color AccentColorDark1 { get; set; }
+    internal static Color AccentColorDark2 { get; set; }
+    internal static Color AccentColorDark3 { get; set; }
+
+    #endregion
+
     internal static UISettings _UISettings
     {
         get
@@ -51,7 +73,6 @@ internal static Color GetSystemAccentColor()
     internal static void UpdateAccentColors()
     {
         Color systemAccent = GetSystemAccentColor();
-        Color primaryAccent, secondaryAccent, tertiaryAccent;
 
         if (systemAccent != _currentApplicationAccentColor)
         {
@@ -61,19 +82,46 @@ internal static void UpdateAccentColors()
         if (ThemeManager.IsSystemThemeLight())
         {
             // In light mode, we use darker shades of the accent color
-            primaryAccent = _UISettings.AccentDark1;
-            secondaryAccent = _UISettings.AccentDark2;
-            tertiaryAccent = _UISettings.AccentDark3;
+            AccentColorDark1 = _UISettings.AccentDark1;
+            AccentColorDark2 = _UISettings.AccentDark2;
+            AccentColorDark3 = _UISettings.AccentDark3;
+        }
+        else
+        {
+            // In dark mode, we use lighter shades of the accent color
+            AccentColorLight1 = _UISettings.AccentLight1;
+            AccentColorLight2 = _UISettings.AccentLight2;
+            AccentColorLight3 = _UISettings.AccentLight3;
+        }
+
+        UpdateColorResources(systemAccent, AccentColorLight1, AccentColorLight2, AccentColorLight3);
+        _currentApplicationAccentColor = systemAccent;
+    }
+
+    internal static void UpdateCachedAccentColors()
+    {
+        Color systemAccent = GetSystemAccentColor();
+
+        if (systemAccent != _currentApplicationAccentColor)
+        {
+            _UISettings.TryUpdateAccentColors();
+        }
+
+        if (ThemeManager.IsSystemThemeLight())
+        {
+            // In light mode, we use darker shades of the accent color
+            AccentColorDark1 = _UISettings.AccentDark1;
+            AccentColorDark2 = _UISettings.AccentDark2;
+            AccentColorDark3 = _UISettings.AccentDark3;
         }
         else
         {
             // In dark mode, we use lighter shades of the accent color
-            primaryAccent = _UISettings.AccentLight1;
-            secondaryAccent = _UISettings.AccentLight2;
-            tertiaryAccent = _UISettings.AccentLight3;
+            AccentColorLight1 = _UISettings.AccentLight1;
+            AccentColorLight2 = _UISettings.AccentLight2;
+            AccentColorLight3 = _UISettings.AccentLight3;
         }
 
-        UpdateColorResources(systemAccent, primaryAccent, secondaryAccent, tertiaryAccent);
         _currentApplicationAccentColor = systemAccent;
     }
 
@@ -86,27 +134,9 @@ private static void UpdateColorResources(
         Color secondaryAccent,
         Color tertiaryAccent)
     {
-#if DEBUG
-        System.Diagnostics.Debug.WriteLine("INFO | SystemAccentColor: " + systemAccent, "System.Windows.Accent");
-        System
-            .Diagnostics
-            .Debug
-            .WriteLine("INFO | SystemAccentColorPrimary: " + primaryAccent, "System.Windows.Accent");
-        System
-            .Diagnostics
-            .Debug
-            .WriteLine("INFO | SystemAccentColorSecondary: " + secondaryAccent, "System.Windows.Accent");
-        System
-            .Diagnostics
-            .Debug
-            .WriteLine("INFO | SystemAccentColorTertiary: " + tertiaryAccent, "System.Windows.Accent");
-#endif
 
         if (!ThemeManager.IsSystemThemeLight())
         {
-#if DEBUG
-            System.Diagnostics.Debug.WriteLine("INFO | Text on accent is DARK", "System.Windows.Accent");
-#endif
             Application.Current.Resources["TextOnAccentFillColorPrimary"] = 
                     Color.FromArgb( 0xFF, 0x00, 0x00, 0x00);
 
@@ -124,9 +154,6 @@ private static void UpdateColorResources(
         }
         else
         {
-#if DEBUG
-            System.Diagnostics.Debug.WriteLine("INFO | Text on accent is LIGHT", "System.Windows.Accent");
-#endif
             Application.Current.Resources["TextOnAccentFillColorPrimary"] = 
                     Color.FromArgb( 0xFF, 0xFF, 0xFF, 0xFF);