Add acrylic blur & DWM caption color support

QuickLook.Common/Helpers/WindowHelper.cs

@@ -168,6 +168,40 @@ public static class WindowHelper
         Marshal.FreeHGlobal(accentPtr);
     }
 
+    public static void EnableAcrylicBlur(Window window, Color tintColor)
+    {
+        window.Background = Brushes.Transparent;
+
+        var hwnd = new WindowInteropHelper(window).EnsureHandle();
+
+        if (!window.AllowsTransparency && HwndSource.FromHwnd(hwnd) is HwndSource hwndSource)
+        {
+            hwndSource.CompositionTarget.BackgroundColor = Colors.Transparent;
+        }
+
+        var margins = new Dwmapi.Margins(-1, -1, -1, -1);
+        Dwmapi.DwmExtendFrameIntoClientArea(hwnd, ref margins);
+
+        var accent = new AccentPolicy();
+        var accentStructSize = Marshal.SizeOf(accent);
+        accent.AccentState = AccentState.AccentEnableAcrylicblurbehind;
+        accent.GradientColor = ToAbgr(tintColor, 0.8);
+
+        var accentPtr = Marshal.AllocHGlobal(accentStructSize);
+        Marshal.StructureToPtr(accent, accentPtr, false);
+
+        var data = new WindowCompositionAttributeData
+        {
+            Attribute = WindowCompositionAttribute.WcaAccentPolicy,
+            SizeOfData = accentStructSize,
+            Data = accentPtr
+        };
+
+        User32.SetWindowCompositionAttribute(hwnd, ref data);
+
+        Marshal.FreeHGlobal(accentPtr);
+    }
+
     public static void DisableDwmBlur(Window window)
     {
         var accent = new AccentPolicy();
@@ -202,6 +236,12 @@ public static class WindowHelper
             var micaEnabled = 0;
             Dwmapi.DwmSetWindowAttribute(hwnd, (uint)Dwmapi.WindowAttribute.MicaEffect, ref micaEnabled, Marshal.SizeOf(typeof(int)));
         }
+
+        if (Environment.OSVersion.Version >= new Version(10, 0, 22000))
+        {
+            var captionColor = -1;
+            Dwmapi.DwmSetWindowAttribute(hwnd, (uint)Dwmapi.WindowAttribute.CaptionColor, ref captionColor, Marshal.SizeOf(typeof(int)));
+        }
     }
 
     private static void EnableDwmBlur(Window window, bool isDarkTheme, uint dwAttribute, int pvAttribute)
@@ -209,15 +249,21 @@ public static class WindowHelper
         // Mica will handle the color
         window.Background = Brushes.Transparent;
 
-        var hwnd = new WindowInteropHelper(window).Handle;
+        var hwnd = new WindowInteropHelper(window).EnsureHandle();
 
         if (!window.AllowsTransparency && HwndSource.FromHwnd(hwnd) is HwndSource hwndSource)
         {
             hwndSource.CompositionTarget.BackgroundColor = Colors.Transparent;
         }
 
+        if (Environment.OSVersion.Version >= new Version(10, 0, 22000))
+        {
+            var captionColor = -2;
+            Dwmapi.DwmSetWindowAttribute(hwnd, (uint)Dwmapi.WindowAttribute.CaptionColor, ref captionColor, Marshal.SizeOf(typeof(int)));
+        }
+
         var isDarkThemeInt = isDarkTheme ? 1 : 0;
-        Dwmapi.DwmSetWindowAttribute(hwnd, (uint)Dwmapi.WindowAttribute.UseImmersiveDarkMode, ref isDarkThemeInt, Marshal.SizeOf(typeof(bool)));
+        Dwmapi.DwmSetWindowAttribute(hwnd, (uint)Dwmapi.WindowAttribute.UseImmersiveDarkMode, ref isDarkThemeInt, Marshal.SizeOf(typeof(int)));
 
         var margins = new Dwmapi.Margins(-1, -1, -1, -1);
         Dwmapi.DwmExtendFrameIntoClientArea(hwnd, ref margins);
@@ -260,7 +306,16 @@ public static class WindowHelper
         AccentEnableGradient = 1,
         AccentEnableTransparentgradient = 2,
         AccentEnableBlurbehind = 3,
-        AccentInvalidState = 4,
+        AccentEnableAcrylicblurbehind = 4,
+        AccentInvalidState = 5,
+    }
+
+    private static uint ToAbgr(Color color, double alphaScale)
+    {
+        return (uint)(color.R << 0 |
+            color.G << 8 |
+            color.B << 16 |
+            (int)(color.A * alphaScale) << 24);
     }
 
     [StructLayout(LayoutKind.Sequential)]

QuickLook.Common/NativeMethods/Dwmapi.cs

@@ -33,6 +33,7 @@ public static class Dwmapi
     public enum WindowAttribute
     {
         UseImmersiveDarkMode = 20,
+        CaptionColor = 35,
         SystembackdropType = 38,
         MicaEffect = 1029,
     }
@@ -44,9 +45,8 @@ public static class Dwmapi
         Mica = 2,
         Acrylic = 3, // Automatically selects the best Acrylic effect available on the system (Acrylic11 > Acrylic10)
         Tabbed = 4,
-
-        Acrylic10, // Windows 10 style, supported on Windows 10 and 11
-        Acrylic11, // Windows 11 style, supported on Windows 11 22523+ (Insider) and 22621+ (Stable)
+        Acrylic10 = 5, // Windows 10 style, supported on Windows 10 and 11
+        Acrylic11 = 6, // Windows 11 style, supported on Windows 11 22523+ (Insider) and 22621+ (Stable)
     }
 
     [DllImport("DwmApi.dll")]

QuickLook/ViewerWindow.xaml.cs

@@ -29,7 +29,9 @@ using System.Windows.Shell;
 using Wpf.Ui.Violeta.Controls;
 using static QuickLook.Common.NativeMethods.Dwmapi;
 using Brush = System.Windows.Media.Brush;
+using Color = System.Windows.Media.Color;
 using FontFamily = System.Windows.Media.FontFamily;
+using SolidColorBrush = System.Windows.Media.SolidColorBrush;
 using Size = System.Windows.Size;
 
 namespace QuickLook;
@@ -180,6 +182,7 @@ public partial class ViewerWindow : Window
             && SystemParameters.IsGlassEnabled
             && !App.IsGPUInBlacklist;
         var backdrop = GetBackdropOption();
+        var keepsTransparentBackground = useTransparency && backdrop != SystembackdropType.None;
 
         var windowChrome = WindowChrome.GetWindowChrome(this);
         windowChrome?.GlassFrameThickness = useTransparency ? new Thickness(1) : new Thickness(0);
@@ -194,7 +197,7 @@ public partial class ViewerWindow : Window
         }
 
         var customColor = SettingHelper.Get("WindowBackgroundColor", string.Empty, "QuickLook");
-        if (!string.IsNullOrEmpty(customColor))
+        if (!keepsTransparentBackground && !string.IsNullOrEmpty(customColor))
         {
             try
             {
@@ -249,8 +252,45 @@ public partial class ViewerWindow : Window
                 }
                 else if (App.IsWin10)
                 {
+                    var acrylicTint = GetAcrylicTintColor();
+
                     WindowHelper.DisableDwmBlur(this);
-                    WindowHelper.EnableBlur(this);
+                    WindowHelper.EnableAcrylicBlur(this, acrylicTint);
+                }
+                else
+                {
+                    Background = (Brush)FindResource("MainWindowBackgroundNoTransparent");
+                }
+
+                break;
+
+            case SystembackdropType.Acrylic10:
+                if (App.IsWin10 || App.IsWin11)
+                {
+                    var acrylicTint = GetAcrylicTintColor();
+
+                    WindowHelper.DisableDwmBlur(this);
+                    WindowHelper.EnableAcrylicBlur(this, acrylicTint);
+                }
+                else
+                {
+                    Background = (Brush)FindResource("MainWindowBackgroundNoTransparent");
+                }
+
+                break;
+
+            case SystembackdropType.Acrylic11:
+                if (App.IsWin11 && Environment.OSVersion.Version >= new Version(10, 0, 22523))
+                {
+                    WindowHelper.DisableDwmBlur(this);
+                    WindowHelper.EnableBackdropAcrylicBlur(this, CurrentTheme == Themes.Dark);
+                }
+                else if (App.IsWin10 || App.IsWin11)
+                {
+                    var acrylicTint = GetAcrylicTintColor();
+
+                    WindowHelper.DisableDwmBlur(this);
+                    WindowHelper.EnableAcrylicBlur(this, acrylicTint);
                 }
                 else
                 {
@@ -306,6 +346,27 @@ public partial class ViewerWindow : Window
         }
     }
 
+    private Color GetAcrylicTintColor()
+    {
+        var customColor = SettingHelper.Get("WindowBackgroundColor", string.Empty, "QuickLook");
+
+        if (!string.IsNullOrEmpty(customColor))
+        {
+            try
+            {
+                return ((SolidColorBrush)new System.Windows.Media.BrushConverter().ConvertFromString(customColor)).Color;
+            }
+            catch
+            {
+                // ignore invalid color
+            }
+        }
+
+        return Background is SolidColorBrush currentBrush
+            ? currentBrush.Color
+            : ((SolidColorBrush)FindResource("MainWindowBackground")).Color;
+    }
+
     private static SystembackdropType GetBackdropOption()
     {
         var option = SettingHelper.Get("WindowBackdrop", nameof(SystembackdropType.Auto), "QuickLook")?.Trim();