- A+
所属分类：.NET技术
众所周知，UWP 使用的窗口模型是 CoreWindow，但是 UWP 本身只是一个应用模型，所以完全可以创建 win32 窗口，那么我们可以不可以创建一个 win32 窗口，然后像 XAML 岛 (XAML Islands) 一样把 XAML 托管上去呢？本篇将讲述如何利用 WAS (Windows App SDK，俗称 WinUI3) 在 UWP 创建一个 XAML 岛窗口。
演示视频：https://x.com/wherewhere7/status/1721570411388039587
由于 WAS 在 win32 应用模型下本身就是个 XAML 岛，所以 WAS 对 XAML 岛的支持要比 WUXC (Windows.UI.Xaml.Controls) 要好多了，接下来的内容大多是将 WAS 中实现窗口的方法迁移到 C#。
首先，不管是 WUXC 还是 WAS 的 XAML 岛都会判断当前的应用模型是否为ClassicDesktop，所以我们需要利用Detours劫持AppPolicyGetWindowingModel方法。具体内容如下：
#r "nuget:Detours.Win32Metadata" #r "nuget:Microsoft.Windows.CsWin32" using System; using System.Runtime.CompilerServices; using System.Runtime.InteropServices; using Windows.Win32; using Windows.Win32.Foundation; using Windows.Win32.Storage.Packaging.Appx; using Detours = Microsoft.Detours.PInvoke; /// <summary> /// Represents a hook for the <see cref="PInvoke.AppPolicyGetWindowingModel(HANDLE, AppPolicyWindowingModel*)"/> function. /// </summary> public sealed partial class HookWindowingModel : IDisposable { /// <summary> /// The value that indicates whether the class has been disposed. /// </summary> private bool disposed; /// <summary> /// The reference count for the hook. /// </summary> private static int refCount; /// <summary> /// The value that represents the current process token. /// </summary> private const int currentProcessToken = -6; /// <remarks>The original <see cref="PInvoke.AppPolicyGetWindowingModel(HANDLE, AppPolicyWindowingModel*)"/> function.</remarks> /// <inheritdoc cref="PInvoke.AppPolicyGetWindowingModel(HANDLE, AppPolicyWindowingModel*)"/> private static unsafe delegate* unmanaged[Stdcall]<HANDLE, AppPolicyWindowingModel*, WIN32_ERROR> AppPolicyGetWindowingModel; /// <summary> /// Initializes a new instance of the <see cref="HookWindowingModel"/> class. /// </summary> public HookWindowingModel() { refCount++; StartHook(); } /// <summary> /// Finalizes this instance of the <see cref="HookWindowingModel"/> class. /// </summary> ~HookWindowingModel() { Dispose(); } /// <summary> /// Gets the value that indicates whether the hook is active. /// </summary> public static bool IsHooked { get; private set; } /// <summary> /// Gets or sets the windowing model to use when the hooked <see cref="PInvoke.AppPolicyGetWindowingModel(HANDLE, AppPolicyWindowingModel*)"/> function is called. /// </summary> internal static AppPolicyWindowingModel WindowingModel { get; set; } = AppPolicyWindowingModel.AppPolicyWindowingModel_ClassicDesktop; /// <summary> /// Starts the hook for the <see cref="PInvoke.AppPolicyGetWindowingModel(HANDLE, AppPolicyWindowingModel*)"/> function. /// </summary> private static unsafe void StartHook() { if (!IsHooked) { using FreeLibrarySafeHandle library = PInvoke.GetModuleHandle("KERNEL32.dll"); if (!library.IsInvalid && NativeLibrary.TryGetExport(library.DangerousGetHandle(), nameof(PInvoke.AppPolicyGetWindowingModel), out nint appPolicyGetWindowingModel)) { void* appPolicyGetWindowingModelPtr = (void*)appPolicyGetWindowingModel; delegate* unmanaged[Stdcall]<HANDLE, AppPolicyWindowingModel*, WIN32_ERROR> overrideAppPolicyGetWindowingModel = &OverrideAppPolicyGetWindowingModel; _ = Detours.DetourRestoreAfterWith(); _ = Detours.DetourTransactionBegin(); _ = Detours.DetourUpdateThread(PInvoke.GetCurrentThread()); _ = Detours.DetourAttach(ref appPolicyGetWindowingModelPtr, overrideAppPolicyGetWindowingModel); _ = Detours.DetourTransactionCommit(); AppPolicyGetWindowingModel = (delegate* unmanaged[Stdcall]<HANDLE, AppPolicyWindowingModel*, WIN32_ERROR>)appPolicyGetWindowingModelPtr; IsHooked = true; } } } /// <summary> /// Ends the hook for the <see cref="PInvoke.AppPolicyGetWindowingModel(HANDLE, AppPolicyWindowingModel*)"/> function. /// </summary> private static unsafe void EndHook() { if (--refCount == 0 && IsHooked) { void* appPolicyGetWindowingModelPtr = AppPolicyGetWindowingModel; delegate* unmanaged[Stdcall]<HANDLE, AppPolicyWindowingModel*, WIN32_ERROR> overrideAppPolicyGetWindowingModel = &OverrideAppPolicyGetWindowingModel; _ = Detours.DetourTransactionBegin(); _ = Detours.DetourUpdateThread(PInvoke.GetCurrentThread()); _ = Detours.DetourDetach(&appPolicyGetWindowingModelPtr, overrideAppPolicyGetWindowingModel); _ = Detours.DetourTransactionCommit(); AppPolicyGetWindowingModel = null; IsHooked = false; } } /// <param name="policy">A pointer to a variable of the <a href="https://docs.microsoft.com/windows/win32/api/appmodel/ne-appmodel-apppolicywindowingmodel">AppPolicyWindowingModel</a> enumerated type. /// When the function returns successfully, the variable contains the <see cref="WindowingModel"/> when the identified process is current; otherwise, the windowing model of the identified process.</param> /// <remarks>The overridden <see cref="PInvoke.AppPolicyGetWindowingModel(HANDLE, AppPolicyWindowingModel*)"/> function.</remarks> /// <inheritdoc cref="PInvoke.AppPolicyGetWindowingModel(HANDLE, AppPolicyWindowingModel*)"/> [UnmanagedCallersOnly(CallConvs = [typeof(CallConvStdcall)])] private static unsafe WIN32_ERROR OverrideAppPolicyGetWindowingModel(HANDLE processToken, AppPolicyWindowingModel* policy) { if ((int)processToken.Value == currentProcessToken) { *policy = WindowingModel; return WIN32_ERROR.ERROR_SUCCESS; } return AppPolicyGetWindowingModel(processToken, policy); } /// <inheritdoc/> public void Dispose() { if (!disposed && IsHooked) { EndHook(); } GC.SuppressFinalize(this); disposed = true; } }准备工作完成，接下来我们就可以创建窗口了，首先我们需要新创建一个线程，CoreWindow 线程无法新建 XAML 岛，不过在 XAML 岛线程可以，新建线程只需要用Thread就行了。
new Thread(() => { ... });WAS 提供了AppWindow来管理 win32 窗口，我们只需要使用它创建一个窗口就行了。
AppWindow window = AppWindow.Create();接下来我们需要创建 XAML 岛，这时我们就需要利用上面劫持器来劫持获取应用模型的方法了。
DispatcherQueueController controller; DesktopWindowXamlSource source; using (HookWindowingModel hook = new()) { controller = DispatcherQueueController.CreateOnCurrentThread(); source = new DesktopWindowXamlSource(); }然后我们就可以把 XAML 岛糊到之前创建的 AppWindow 上了。
source.Initialize(window.Id); DesktopChildSiteBridge bridge = source.SiteBridge; bridge.ResizePolicy = ContentSizePolicy.ResizeContentToParentWindow; bridge.Show(); DispatcherQueue dispatcherQueue = controller.DispatcherQueue; window.AssociateWithDispatcherQueue(dispatcherQueue);由于 XAML 岛存在的一些特性，当窗口扩展标题栏或者全屏化的是否窗口内容并不会跟着变化，所以我们需要一些小魔法来让它在变化时调整大小。
window.Changed += (sender, args) => { if (args.DidPresenterChange) { bridge.ResizePolicy = ContentSizePolicy.None; bridge.ResizePolicy = ContentSizePolicy.ResizeContentToParentWindow; } };最后不要忘了保持当前线程，不然这里跑完了窗口就退出了。
dispatcherQueue.RunEventLoop(); await controller.ShutdownQueueAsync();当窗口关闭后记得执行DispatcherQueue.EnqueueEventLoopExit()来释放保持的线程。
最后把之前的东西组合起来，再加点东西：
/// <summary> /// Create a new <see cref="DesktopWindow"/> instance. /// </summary> /// <param name="launched">Do something after <see cref="DesktopWindowXamlSource"/> created.</param> /// <returns>The new instance of <see cref="DesktopWindow"/>.</returns> public static Task<DesktopWindow> CreateAsync(Action<DesktopWindowXamlSource> launched) { TaskCompletionSource<DesktopWindow> taskCompletionSource = new(); new Thread(async () => { try { DispatcherQueueController controller; DesktopWindowXamlSource source; AppWindow window = AppWindow.Create(); using (HookWindowingModel hook = new()) { controller = DispatcherQueueController.CreateOnCurrentThread(); source = new DesktopWindowXamlSource(); } source.Initialize(window.Id); DesktopChildSiteBridge bridge = source.SiteBridge; bridge.ResizePolicy = ContentSizePolicy.ResizeContentToParentWindow; bridge.Show(); window.Changed += (sender, args) => { if (args.DidPresenterChange) { bridge.ResizePolicy = ContentSizePolicy.None; bridge.ResizePolicy = ContentSizePolicy.ResizeContentToParentWindow; } }; DispatcherQueue dispatcherQueue = controller.DispatcherQueue; window.AssociateWithDispatcherQueue(dispatcherQueue); TrackWindow(window); launched(source); DesktopWindow desktopWindow = new() { AppWindow = window, WindowXamlSource = source }; taskCompletionSource.SetResult(desktopWindow); dispatcherQueue.RunEventLoop(); await controller.ShutdownQueueAsync(); } catch (Exception e) { taskCompletionSource.SetException(e); } }) { Name = nameof(DesktopWindowXamlSource) }.Start(); return taskCompletionSource.Task; } /// <summary> /// Create a new <see cref="DesktopWindow"/> instance. /// </summary> /// <param name="dispatcherQueue">The <see cref="DispatcherQueue"/> to provide thread.</param> /// <param name="launched">Do something after <see cref="DesktopWindowXamlSource"/> created.</param> /// <returns>The new instance of <see cref="DesktopWindow"/>.</returns> public static Task<DesktopWindow> CreateAsync(DispatcherQueue dispatcherQueue, Action<DesktopWindowXamlSource> launched) { TaskCompletionSource<DesktopWindow> taskCompletionSource = new(); _ = dispatcherQueue.TryEnqueue(() => { try { DesktopWindowXamlSource source; AppWindow window = AppWindow.Create(); window.AssociateWithDispatcherQueue(dispatcherQueue); TrackWindow(window); using (HookWindowingModel hook = new()) { source = new DesktopWindowXamlSource(); } source.Initialize(window.Id); DesktopChildSiteBridge bridge = source.SiteBridge; bridge.ResizePolicy = ContentSizePolicy.ResizeContentToParentWindow; bridge.Show(); window.Changed += (sender, args) => { if (args.DidPresenterChange) { bridge.ResizePolicy = ContentSizePolicy.None; bridge.ResizePolicy = ContentSizePolicy.ResizeContentToParentWindow; } }; launched(source); DesktopWindow desktopWindow = new() { AppWindow = window, WindowXamlSource = source }; taskCompletionSource.SetResult(desktopWindow); } catch (Exception e) { taskCompletionSource.SetException(e); } }); return taskCompletionSource.Task; } private static void TrackWindow(AppWindow window) { if (ActiveDesktopWindows.ContainsKey(window.DispatcherQueue)) { ActiveDesktopWindows[window.DispatcherQueue] += 1; } else { ActiveDesktopWindows[window.DispatcherQueue] = 1; } window.Destroying -= AppWindow_Destroying; window.Destroying += AppWindow_Destroying; } private static void AppWindow_Destroying(AppWindow sender, object args) { if (ActiveDesktopWindows.TryGetValue(sender.DispatcherQueue, out ulong num)) { num--; if (num == 0) { ActiveDesktopWindows.Remove(sender.DispatcherQueue); sender.DispatcherQueue.EnqueueEventLoopExit(); return; } ActiveDesktopWindows[sender.DispatcherQueue] = num; } } private static Dictionary<DispatcherQueue, ulong> ActiveDesktopWindows { get; } = [];其中DesktopWindow是用来存放 AppWindow 和 DesktopWindowXamlSource的类，如果不嫌麻烦的话可以包裹成一个和 Microsoft.UI.Xaml.Window一样的东西。
