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？本篇将讲述如何在 UWP 创建一个 XAML 岛窗口。
首先，XAML 岛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，新建线程只需要用Thread就行了。
new Thread(() => { ... });首先我们需要创建 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。
DesktopWindowXamlSource source;
using (HookWindowingModel hook = new())
{
source = new DesktopWindowXamlSource();
}微软并没有单独提供一个 Win32 窗口管理的轮子，如果引用 Windows Forms 就太臃肿了，于是我们需要手动制作一个 Window 类：
/// <summary>
/// Represents a system-managed container for the content of an app.
/// </summary>
public partial class DesktopWindow
{
private bool m_bIsClosed = false;
private DesktopWindowXamlSource m_source;
private IDesktopWindowXamlSourceNative m_native;
private readonly HWND m_hwnd;
private readonly WNDCLASSEXW m_wndClassEx;
/// <summary>
/// Initializes a new instance of the <see cref="DesktopWindow"/> class.
/// </summary>
public DesktopWindow()
{
m_wndClassEx = RegisterDesktopWindowClass(WNDPROC);
m_hwnd = CreateDesktopWindow();
}
/// <summary>
/// Gets the event dispatcher for the window.
/// </summary>
public CoreDispatcher Dispatcher { get; private set; }
/// <summary>
/// Gets the <see cref="DesktopWindowXamlSource"/> to provide XAML for this window.
/// </summary>
public DesktopWindowXamlSource WindowXamlSource
{
get => m_source;
private init
{
if (m_source != value)
{
m_source = value;
if (value != null)
{
Dispatcher = CoreWindow.GetForCurrentThread().Dispatcher;
m_native = value.As<IDesktopWindowXamlSourceNative>();
m_native.AttachToWindow(m_hwnd);
ResizeWindowToDesktopWindowXamlSourceWindowDimensions();
}
else
{
m_native = null;
}
}
}
}
/// <summary>
/// Shows the window and activates it.
/// </summary>
public void Show() => _ = PInvoke.ShowWindow(m_hwnd, SHOW_WINDOW_CMD.SW_NORMAL);
private LRESULT WNDPROC(HWND hWnd, uint message, WPARAM wParam, LPARAM lParam)
{
switch (message)
{
case PInvoke.WM_PAINT:
HDC hdc = PInvoke.BeginPaint(hWnd, out PAINTSTRUCT ps);
_ = PInvoke.GetClientRect(hWnd, out RECT rect);
_ = PInvoke.FillRect(hdc, rect, new DefaultSafeHandle(PInvoke.GetStockObject(GET_STOCK_OBJECT_FLAGS.WHITE_BRUSH)));
_ = PInvoke.EndPaint(hWnd, ps);
return new LRESULT();
case PInvoke.WM_CLOSE when m_bIsClosed:
goto default;
case PInvoke.WM_CLOSE:
m_bIsClosed = true;
goto default;
case PInvoke.WM_SIZE:
ResizeWindowToDesktopWindowXamlSourceWindowDimensions();
return new LRESULT();
case PInvoke.WM_CREATE:
return new LRESULT();
case PInvoke.WM_DESTROY:
PInvoke.PostQuitMessage(0);
return new LRESULT();
default:
return PInvoke.DefWindowProc(hWnd, message, wParam, lParam);
}
}
private void ResizeWindowToDesktopWindowXamlSourceWindowDimensions()
{
if (m_bIsClosed) return;
_ = PInvoke.GetClientRect(m_hwnd, out RECT rect);
_ = PInvoke.SetWindowPos(
m_native.WindowHandle,
new HWND(),
0, 0,
rect.Width, rect.Height,
SET_WINDOW_POS_FLAGS.SWP_NOACTIVATE | SET_WINDOW_POS_FLAGS.SWP_NOZORDER | SET_WINDOW_POS_FLAGS.SWP_SHOWWINDOW);
}
}
public partial class DesktopWindow
{
private static readonly unsafe HINSTANCE g_hInstance = new((void*)Process.GetCurrentProcess().Handle);
// win32 window class name for top-level WinUI desktop windows
private const string s_windowClassName = "WinUIDesktopWin32WindowClass";
// Default window title for top-level WinUI desktop windows
private const string s_defaultWindowTitle = "WinUI Desktop";
private static unsafe WNDCLASSEXW RegisterDesktopWindowClass(WNDPROC lpfnWndProc)
{
if (!PInvoke.GetClassInfoEx(new DefaultSafeHandle(g_hInstance), s_windowClassName, out WNDCLASSEXW wndClassEx))
{
wndClassEx.cbSize = (uint)Marshal.SizeOf(wndClassEx);
wndClassEx.style = WNDCLASS_STYLES.CS_HREDRAW | WNDCLASS_STYLES.CS_VREDRAW;
wndClassEx.cbClsExtra = 0;
wndClassEx.cbWndExtra = 0;
wndClassEx.hCursor = PInvoke.LoadCursor(new HINSTANCE(), PInvoke.IDC_ARROW);
wndClassEx.hbrBackground = (HBRUSH)((nint)SYS_COLOR_INDEX.COLOR_WINDOW + 1);
wndClassEx.hInstance = g_hInstance;
fixed (char* lps_windowClassName = s_windowClassName)
{
wndClassEx.lpszClassName = lps_windowClassName;
}
wndClassEx.lpfnWndProc = lpfnWndProc;
_ = PInvoke.RegisterClassEx(wndClassEx);
return wndClassEx;
}
return default;
}
private static unsafe HWND CreateDesktopWindow() =>
PInvoke.CreateWindowEx(
0, // Extended Style
s_windowClassName, // name of window class
s_defaultWindowTitle, // title-bar string
WINDOW_STYLE.WS_OVERLAPPEDWINDOW | WINDOW_STYLE.WS_VISIBLE, // top-level window
int.MinValue, // default horizontal position
(int)SHOW_WINDOW_CMD.SW_HIDE, // If the y parameter is some other value,
// then the window manager calls ShowWindow with that value as the nCmdShow parameter
int.MinValue, // default width
int.MinValue, // default height
new HWND(), // no owner window
null, // use class menu
new DefaultSafeHandle(g_hInstance),
null);
private partial class DefaultSafeHandle(nint invalidHandleValue, bool ownsHandle) : SafeHandle(invalidHandleValue, ownsHandle)
{
public DefaultSafeHandle(nint handle) : this(handle, true) => SetHandle(handle);
public override bool IsInvalid => handle != nint.Zero;
protected override bool ReleaseHandle() => true;
}
}然后我们就可以初始化一个窗口了。
DesktopWindow window = new() { WindowXamlSource = source };最后不要忘了用消息循环保持当前线程，不然这里跑完了窗口就退出了。
MSG msg = new();
while (msg.message != PInvoke.WM_QUIT)
{
if (PInvoke.PeekMessage(out msg, new HWND(), 0, 0, PEEK_MESSAGE_REMOVE_TYPE.PM_REMOVE))
{
_ = PInvoke.DispatchMessage(msg);
}
}最后把之前的东西组合起来，再加点东西：
/// <summary>
/// Represents a system-managed container for the content of an app.
/// </summary>
public partial class DesktopWindow
{
private bool m_bIsClosed = false;
private DesktopWindowXamlSource m_source;
private IDesktopWindowXamlSourceNative m_native;
private readonly HWND m_hwnd;
private readonly WNDCLASSEXW m_wndClassEx;
/// <summary>
/// Initializes a new instance of the <see cref="DesktopWindow"/> class.
/// </summary>
public DesktopWindow()
{
m_wndClassEx = RegisterDesktopWindowClass(WNDPROC);
m_hwnd = CreateDesktopWindow();
}
/// <summary>
/// Get the handle of the window.
/// </summary>
public nint Hwnd => m_hwnd;
/// <summary>
/// Gets the event dispatcher for the window.
/// </summary>
public CoreDispatcher Dispatcher { get; private set; }
/// <summary>
/// Gets or sets the visual root of an application window.
/// </summary>
public UIElement Content
{
get => WindowXamlSource.Content;
set => WindowXamlSource.Content = value;
}
/// <summary>
/// Gets or sets the XamlRoot in which this element is being viewed.
/// </summary>
[SupportedOSPlatform("Windows10.0.18362.0")]
public XamlRoot XamlRoot
{
get => WindowXamlSource.Content.XamlRoot;
set => WindowXamlSource.Content.XamlRoot = value;
}
/// <summary>
/// Gets or sets a string used for the window title.
/// </summary>
public unsafe string Title
{
get
{
int windowTextLength = PInvoke.GetWindowTextLength(m_hwnd);
char* windowText = stackalloc char[windowTextLength + 1];
_ = PInvoke.GetWindowText(m_hwnd, windowText, windowTextLength + 1);
return new string(windowText);
}
set => _ = PInvoke.SetWindowText(m_hwnd, value);
}
/// <summary>
/// Gets the <see cref="DesktopWindowXamlSource"/> to provide XAML for this window.
/// </summary>
public DesktopWindowXamlSource WindowXamlSource
{
get => m_source;
private init
{
if (m_source != value)
{
m_source = value;
if (value != null)
{
Dispatcher = CoreWindow.GetForCurrentThread().Dispatcher;
m_native = value.As<IDesktopWindowXamlSourceNative>();
m_native.AttachToWindow(m_hwnd);
ResizeWindowToDesktopWindowXamlSourceWindowDimensions();
}
else
{
m_native = null;
}
}
}
}
/// <summary>
/// Occurs when the window has closed.
/// </summary>
public event TypedEventHandler<DesktopWindow, object> Closed;
/// <summary>
/// Shows the window and activates it.
/// </summary>
public void Show() => _ = PInvoke.ShowWindow(m_hwnd, SHOW_WINDOW_CMD.SW_NORMAL);
/// <summary>
/// Sets the icon for the window, using the specified icon path.
/// </summary>
/// <param name="iconPath">The path of the icon.</param>
public unsafe void SetIcon(string iconPath)
{
fixed (char* ptr = iconPath)
{
HANDLE icon = PInvoke.LoadImage(new HINSTANCE(), ptr, GDI_IMAGE_TYPE.IMAGE_ICON, 0, 0, IMAGE_FLAGS.LR_LOADFROMFILE);
_ = PInvoke.SendMessage(m_hwnd, PInvoke.WM_SETICON, PInvoke.ICON_BIG, new LPARAM((nint)icon.Value));
}
}
private LRESULT WNDPROC(HWND hWnd, uint message, WPARAM wParam, LPARAM lParam)
{
switch (message)
{
case PInvoke.WM_PAINT:
HDC hdc = PInvoke.BeginPaint(hWnd, out PAINTSTRUCT ps);
_ = PInvoke.GetClientRect(hWnd, out RECT rect);
_ = PInvoke.FillRect(hdc, rect, new DefaultSafeHandle(PInvoke.GetStockObject(GET_STOCK_OBJECT_FLAGS.WHITE_BRUSH)));
_ = PInvoke.EndPaint(hWnd, ps);
return new LRESULT();
case PInvoke.WM_CLOSE when m_bIsClosed:
goto default;
case PInvoke.WM_CLOSE:
m_bIsClosed = true;
Closed?.Invoke(this, null);
goto default;
case PInvoke.WM_SIZE:
ResizeWindowToDesktopWindowXamlSourceWindowDimensions();
return new LRESULT();
case PInvoke.WM_CREATE:
return new LRESULT();
case PInvoke.WM_DESTROY:
PInvoke.PostQuitMessage(0);
return new LRESULT();
default:
return PInvoke.DefWindowProc(hWnd, message, wParam, lParam);
}
}
private void ResizeWindowToDesktopWindowXamlSourceWindowDimensions()
{
if (m_bIsClosed) return;
_ = PInvoke.GetClientRect(m_hwnd, out RECT rect);
_ = PInvoke.SetWindowPos(
m_native.WindowHandle,
new HWND(),
0, 0,
rect.Width, rect.Height,
SET_WINDOW_POS_FLAGS.SWP_NOACTIVATE | SET_WINDOW_POS_FLAGS.SWP_NOZORDER | SET_WINDOW_POS_FLAGS.SWP_SHOWWINDOW);
}
}
public partial class DesktopWindow
{
private static readonly unsafe HINSTANCE g_hInstance = new((void*)Process.GetCurrentProcess().Handle);
// win32 window class name for top-level WinUI desktop windows
private const string s_windowClassName = "WinUIDesktopWin32WindowClass";
// Default window title for top-level WinUI desktop windows
private const string s_defaultWindowTitle = "WinUI Desktop";
private static unsafe WNDCLASSEXW RegisterDesktopWindowClass(WNDPROC lpfnWndProc)
{
if (!PInvoke.GetClassInfoEx(new DefaultSafeHandle(g_hInstance), s_windowClassName, out WNDCLASSEXW wndClassEx))
{
wndClassEx.cbSize = (uint)Marshal.SizeOf(wndClassEx);
wndClassEx.style = WNDCLASS_STYLES.CS_HREDRAW | WNDCLASS_STYLES.CS_VREDRAW;
wndClassEx.cbClsExtra = 0;
wndClassEx.cbWndExtra = 0;
wndClassEx.hCursor = PInvoke.LoadCursor(new HINSTANCE(), PInvoke.IDC_ARROW);
wndClassEx.hbrBackground = (HBRUSH)((nint)SYS_COLOR_INDEX.COLOR_WINDOW + 1);
wndClassEx.hInstance = g_hInstance;
fixed (char* lps_windowClassName = s_windowClassName)
{
wndClassEx.lpszClassName = lps_windowClassName;
}
wndClassEx.lpfnWndProc = lpfnWndProc;
_ = PInvoke.RegisterClassEx(wndClassEx);
return wndClassEx;
}
return default;
}
private static unsafe HWND CreateDesktopWindow() =>
PInvoke.CreateWindowEx(
0, // Extended Style
s_windowClassName, // name of window class
s_defaultWindowTitle, // title-bar string
WINDOW_STYLE.WS_OVERLAPPEDWINDOW | WINDOW_STYLE.WS_VISIBLE, // top-level window
int.MinValue, // default horizontal position
(int)SHOW_WINDOW_CMD.SW_HIDE, // If the y parameter is some other value,
// then the window manager calls ShowWindow with that value as the nCmdShow parameter
int.MinValue, // default width
int.MinValue, // default height
new HWND(), // no owner window
null, // use class menu
new DefaultSafeHandle(g_hInstance),
null);
private partial class DefaultSafeHandle(nint invalidHandleValue, bool ownsHandle) : SafeHandle(invalidHandleValue, ownsHandle)
{
public DefaultSafeHandle(nint handle) : this(handle, true) => SetHandle(handle);
public override bool IsInvalid => handle != nint.Zero;
protected override bool ReleaseHandle() => true;
}
}
public partial class DesktopWindow
{
/// <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(() =>
{
try
{
DesktopWindowXamlSource source;
using (HookWindowingModel hook = new())
{
source = new DesktopWindowXamlSource();
}
DesktopWindow window = new() { WindowXamlSource = source };
launched(source);
taskCompletionSource.SetResult(window);
MSG msg = new();
while (msg.message != PInvoke.WM_QUIT)
{
if (PInvoke.PeekMessage(out msg, new HWND(), 0, 0, PEEK_MESSAGE_REMOVE_TYPE.PM_REMOVE))
{
_ = PInvoke.DispatchMessage(msg);
}
}
}
catch (Exception e)
{
taskCompletionSource.SetException(e);
}
})
{
Name = nameof(DesktopWindowXamlSource)
}.Start();
return taskCompletionSource.Task;
}
}这样创建的窗口还存在一些问题，但是我不知道该怎么解决，所以该方法还是仅供参考。
最后附上示例应用：https://github.com/wherewhere/CoreAppUWP/tree/wuxc
MUXC 篇：【UWP】让 UWP 自己托管自己 —— Windows App SDK 篇
（由于微软迟迟不正式发布 .NET Core App 对 UWP 的支持，所以本文章实际仍处于未完成状态，源码也暂时未上传至 Github，作者会在微软正式发布之后完善文章并更新源码。
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