WinUI3+C#初始化MPV.Net时无法提供控件句柄的问题

由于WinUI3的XAML控件没有直接暴露HWND，你可以通过创建Win32宿主窗口承载MPV，再将该窗口嵌入WinUI3页面的方式解决问题，具体步骤如下：

1. 确认项目类型 #

使用桌面打包的WinUI3应用（而非UWP版），这类项目对Win32互操作支持更完善。

2. 添加Win32窗口相关P/Invoke声明 #

在项目中添加用于创建和管理宿主窗口的P/Invoke代码：

using System.Runtime.InteropServices;

public static class Win32Native
{
    [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)]
    public static extern IntPtr CreateWindowEx(
        uint dwExStyle,
        string lpClassName,
        string lpWindowName,
        uint dwStyle,
        int x, int y, int nWidth, int nHeight,
        IntPtr hWndParent,
        IntPtr hMenu,
        IntPtr hInstance,
        IntPtr lpParam);

    [DllImport("user32.dll", SetLastError = true)]
    public static extern bool DestroyWindow(IntPtr hWnd);

    [DllImport("user32.dll", SetLastError = true)]
    public static extern uint RegisterClassW([In] ref WNDCLASS lpWndClass);

    public const uint WS_CHILD = 0x40000000;
    public const uint WS_VISIBLE = 0x10000000;
    public const int CW_USEDEFAULT = 0x80000000;

    public struct WNDCLASS
    {
        public uint style;
        public IntPtr lpfnWndProc;
        public int cbClsExtra;
        public int cbWndExtra;
        public IntPtr hInstance;
        public IntPtr hIcon;
        public IntPtr hCursor;
        public IntPtr hbrBackground;
        public string lpszMenuName;
        public string lpszClassName;
    }

    [DllImport("user32.dll")]
    public static extern IntPtr DefWindowProc(IntPtr hWnd, uint msg, IntPtr wParam, IntPtr lParam);
}

3. 在HomePage中实现初始化逻辑 #

3.1 声明核心变量 #

在HomePage类中添加以下字段：

private IntPtr _mpvHostHwnd;
private MpvPlayer _mpvPlayer;
private Windows.UI.Xaml.Hosting.DesktopWindowXamlSource _desktopSource;

3.2 初始化宿主窗口与MPV #

在HomePage的Loaded事件中编写初始化代码：

private void HomePage_Loaded(object sender, RoutedEventArgs e)
{
    // 注册Win32窗口类
    var wc = new Win32Native.WNDCLASS
    {
        lpszClassName = "MPVHostWindow",
        lpfnWndProc = Marshal.GetFunctionPointerForDelegate(new WndProcDelegate(DefWndProc)),
        hInstance = System.Diagnostics.Process.GetCurrentProcess().Handle,
        hbrBackground = IntPtr.Zero
    };
    Win32Native.RegisterClassW(ref wc);

    // 创建子窗口作为MPV的宿主
    _mpvHostHwnd = Win32Native.CreateWindowEx(
        0,
        "MPVHostWindow",
        "",
        Win32Native.WS_CHILD | Win32Native.WS_VISIBLE,
        Win32Native.CW_USEDEFAULT, Win32Native.CW_USEDEFAULT,
        (int)MPVHostGrid.ActualWidth, (int)MPVHostGrid.ActualHeight,
        IntPtr.Zero, IntPtr.Zero, wc.hInstance, IntPtr.Zero);

    // 初始化MPVPlayer
    _mpvPlayer = new MpvPlayer(_mpvHostHwnd, "path/to/libmpv-2.dll");

    // 将Win32窗口嵌入WinUI3页面
    _desktopSource = new Windows.UI.Xaml.Hosting.DesktopWindowXamlSource();
    _desktopSource.Navigate(_mpvHostHwnd);
    MPVHostGrid.Children.Add(_desktopSource);
}

// 窗口过程委托
private delegate IntPtr WndProcDelegate(IntPtr hWnd, uint msg, IntPtr wParam, IntPtr lParam);
private IntPtr DefWndProc(IntPtr hWnd, uint msg, IntPtr wParam, IntPtr lParam)
{
    return Win32Native.DefWindowProc(hWnd, msg, wParam, lParam);
}

3.3 清理资源避免泄漏 #

在HomePage的Unloaded事件中释放资源：

private void HomePage_Unloaded(object sender, RoutedEventArgs e)
{
    _mpvPlayer?.Dispose();
    if (_mpvHostHwnd != IntPtr.Zero)
    {
        Win32Native.DestroyWindow(_mpvHostHwnd);
    }
    _desktopSource?.Dispose();
}

4. 配置XAML布局 #

在HomePage的XAML中添加用于承载Win32窗口的Grid：

<Grid x:Name="MPVHostGrid" Loaded="HomePage_Loaded" Unloaded="HomePage_Unloaded"/>

替代方案：修复WindowsFormsHost使用问题 #

若你坚持使用WinFormsHost，需完成以下配置：

• 安装Microsoft.WindowsAppSDK和System.Windows.Forms NuGet包
• 在项目文件中启用Windows Forms兼容：

<PropertyGroup>
  <UseWindowsForms>true</UseWindowsForms>
</PropertyGroup>

• 在XAML中添加WindowsFormsHost及承载控件：

<WindowsFormsHost x:Name="WinFormsHost">
    <wf:Panel x:Name="MPVPanel"/>
</WindowsFormsHost>

• 初始化时传入Panel的句柄：

_mpvPlayer = new MpvPlayer(MPVPanel.Handle, "path/to/libmpv-2.dll");

内容的提问来源于stack exchange，提问作者PigeonMuyz