add transparent backdrop

src/Snap.Hutao/Snap.Hutao.Win32/NativeMethods.txt

@@ -47,12 +47,14 @@ GetCursorPos
 GetDC
 GetDpiForWindow
 GetForegroundWindow
+GetWindowLongPtrW
 GetWindowPlacement
 GetWindowThreadProcessId
 ReleaseDC
 RegisterHotKey
 SendInput
 SetForegroundWindow
+SetWindowLongPtrW
 UnregisterHotKey
 
 // COM
@@ -74,6 +76,7 @@ E_FAIL
 INFINITE
 RPC_E_WRONG_THREAD
 MAX_PATH
+WM_ERASEBKGND
 WM_GETMINMAXINFO
 WM_HOTKEY
 WM_NCRBUTTONDOWN
@@ -89,6 +92,7 @@ LPTHREAD_START_ROUTINE
 
 // UI.WindowsAndMessaging
 MINMAXINFO
+WINDOW_EX_STYLE
 
 // System.Com
 CWMO_FLAGS

src/Snap.Hutao/Snap.Hutao.Win32/Snap.Hutao.Win32.csproj

@@ -1,9 +1,10 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
     <TargetFramework>net8.0-windows10.0.22621.0</TargetFramework>
     <ImplicitUsings>disable</ImplicitUsings>
     <Nullable>enable</Nullable>
+    <PlatformTarget>x64</PlatformTarget>
   </PropertyGroup>
 
   <ItemGroup>

src/Snap.Hutao/Snap.Hutao/Core/Windowing/Backdrop/TransparentBackdrop.cs

@@ -0,0 +1,67 @@
+// Copyright (c) DGP Studio. All rights reserved.
+// Licensed under the MIT license.
+
+using Microsoft.UI;
+using Microsoft.UI.Composition;
+using Microsoft.UI.Xaml;
+using Microsoft.UI.Xaml.Media;
+using Windows.UI;
+
+namespace Snap.Hutao.Core.Windowing.Backdrop;
+
+internal sealed class TransparentBackdrop : SystemBackdrop, IDisposable, IBackdropNeedEraseBackground
+{
+    private readonly object compositorLock = new();
+
+    private Color tintColor;
+    private Windows.UI.Composition.CompositionColorBrush? brush;
+    private Windows.UI.Composition.Compositor? compositor;
+
+    public TransparentBackdrop()
+        : this(Colors.Transparent)
+    {
+    }
+
+    public TransparentBackdrop(Color tintColor)
+    {
+        this.tintColor = tintColor;
+    }
+
+    internal Windows.UI.Composition.Compositor Compositor
+    {
+        get
+        {
+            if (compositor is null)
+            {
+                lock (compositorLock)
+                {
+                    if (compositor is null)
+                    {
+                        DispatcherQueue.EnsureSystemDispatcherQueue();
+                        compositor = new Windows.UI.Composition.Compositor();
+                    }
+                }
+            }
+
+            return compositor;
+        }
+    }
+
+    public void Dispose()
+    {
+        compositor?.Dispose();
+    }
+
+    protected override void OnTargetConnected(ICompositionSupportsSystemBackdrop connectedTarget, XamlRoot xamlRoot)
+    {
+        brush ??= Compositor.CreateColorBrush(tintColor);
+        connectedTarget.SystemBackdrop = brush;
+    }
+
+    protected override void OnTargetDisconnected(ICompositionSupportsSystemBackdrop disconnectedTarget)
+    {
+        disconnectedTarget.SystemBackdrop = null;
+    }
+}
+
+internal interface IBackdropNeedEraseBackground;

src/Snap.Hutao/Snap.Hutao/Core/Windowing/BackdropType.cs

@@ -9,6 +9,8 @@ namespace Snap.Hutao.Core.Windowing;
 [HighQuality]
 internal enum BackdropType
 {
+    Transparent,
+
     /// <summary>
     /// 无
     /// </summary>

src/Snap.Hutao/Snap.Hutao/Core/Windowing/WindowController.cs

@@ -9,6 +9,7 @@ using Microsoft.UI.Xaml.Media;
 using Snap.Hutao.Core.LifeCycle;
 using Snap.Hutao.Core.Setting;
 using Snap.Hutao.Service;
+using System.Diagnostics;
 using System.IO;
 using Windows.Graphics;
 using Windows.UI;
@@ -157,6 +158,7 @@ internal sealed class WindowController
     {
         window.SystemBackdrop = backdropType switch
         {
+            BackdropType.Transparent => new Backdrop.TransparentBackdrop(),
             BackdropType.MicaAlt => new MicaBackdrop() { Kind = MicaKind.BaseAlt },
             BackdropType.Mica => new MicaBackdrop() { Kind = MicaKind.Base },
             BackdropType.Acrylic => new DesktopAcrylicBackdrop(),

src/Snap.Hutao/Snap.Hutao/Core/Windowing/WindowExtension.cs

@@ -3,6 +3,10 @@
 
 using Microsoft.UI.Xaml;
 using System.Runtime.CompilerServices;
+using Windows.Win32.Foundation;
+using Windows.Win32.UI.WindowsAndMessaging;
+using WinRT.Interop;
+using static Windows.Win32.PInvoke;
 
 namespace Snap.Hutao.Core.Windowing;
 
@@ -16,4 +20,12 @@ internal static class WindowExtension
         WindowController windowController = new(window, window.WindowOptions, serviceProvider);
         WindowControllers.Add(window, windowController);
     }
+
+    public static void SetLayeredWindow(this Window window)
+    {
+        HWND hwnd = (HWND)WindowNative.GetWindowHandle(window);
+        nint style = GetWindowLongPtr(hwnd, WINDOW_LONG_PTR_INDEX.GWL_EXSTYLE);
+        style |= (nint)WINDOW_EX_STYLE.WS_EX_LAYERED;
+        SetWindowLongPtr(hwnd, WINDOW_LONG_PTR_INDEX.GWL_EXSTYLE, style);
+    }
 }

src/Snap.Hutao/Snap.Hutao/Core/Windowing/WindowSubclass.cs

@@ -2,6 +2,7 @@
 // Licensed under the MIT license.
 
 using Microsoft.UI.Xaml;
+using Snap.Hutao.Core.Windowing.Backdrop;
 using Snap.Hutao.Core.Windowing.HotKey;
 using Windows.Win32.Foundation;
 using Windows.Win32.UI.Shell;
@@ -110,6 +111,16 @@ internal sealed class WindowSubclass : IDisposable
                     hotKeyController.OnHotKeyPressed(*(HotKeyParameter*)&lParam);
                     break;
                 }
+
+            case WM_ERASEBKGND:
+                {
+                    if (window.SystemBackdrop is IBackdropNeedEraseBackground)
+                    {
+                        return (LRESULT)(int)(BOOL)true;
+                    }
+
+                    break;
+                }
         }
 
         return DefSubclassProc(hwnd, uMsg, wParam, lParam);