c# - 托管窗口时出现 BuildWindowCore 错误

Question

我正在尝试在我的进程中托管另一个进程的窗口。为此，我使用 HwndHost，如下所示:

public class MyHandle : HwndHost
{
    #region User32.dll

    private static Int32 WS_VISIBLE = 0x10000000;
    private static Int32 WS_CHILD = 0x40000000;
    private static Int32 WS_BORDER = 0x00800000;
    private static Int32 GWL_STYLE = -16;

    [DllImport("user32.dll")]
    private static extern int GetWindowThreadProcessId(IntPtr hWnd, IntPtr procid);

    [DllImport("user32.dll")]
    private static extern int SetWindowLong(IntPtr hWnd, int nIndex, int dwNewLong);

    [DllImport("user32.dll", SetLastError = true)]
    private static extern int GetWindowLong(IntPtr hWnd, int nIndex);

    [DllImport("user32")]
    private static extern IntPtr SetParent(IntPtr hWnd, IntPtr hWndParent);
    #endregion
    private Action WindowCoreBuilt = null;

    private IntPtr m_window = IntPtr.Zero;

    public MyHandle(IntPtr window, Action windowCoreBuiltDelegate)
    {
        m_window = window;
        WindowCoreBuilt = windowCoreBuiltDelegate;
    }

    protected override System.Runtime.InteropServices.HandleRef BuildWindowCore(System.Runtime.InteropServices.HandleRef hwndParent)
    {
        int guestStyle = SetWindowLong(m_window, GWL_STYLE, WS_CHILD | WS_BORDER | WS_VISIBLE);
        SetParent(m_window, hwndParent.Handle);

        HandleRef hwnd = new HandleRef(this, m_window);
        InvokeHelper.InvokeDelegate(this.Dispatcher, () => WindowCoreBuilt());
        return hwnd;
    }

    protected override void DestroyWindowCore(HandleRef hwnd)
    {
    }
}

它通常有效，但有时我会遇到这样的异常:

System.InvalidOperationException: BuildWindowCore failed to return the hosted child window handle.
   at System.Windows.Interop.HwndHost.BuildWindow(HandleRef hwndParent)
   at System.Windows.Interop.HwndHost.BuildOrReparentWindow()
   at System.Windows.Interop.HwndHost.OnSourceChanged(Object sender, SourceChangedEventArgs e)
   at System.Windows.SourceChangedEventArgs.InvokeEventHandler(Delegate genericHandler, Object genericTarget)
   at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
   at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)
   at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
   at System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args)
   at System.Windows.UIElement.RaiseEvent(RoutedEventArgs e)
   at System.Windows.PresentationSource.UpdateSourceOfElement(DependencyObject doTarget, DependencyObject doAncestor, DependencyObject doOldParent)
   at System.Windows.PresentationSource.OnVisualAncestorChanged(DependencyObject uie, AncestorChangedEventArgs e)
   at System.Windows.UIElement.OnVisualAncestorChanged(Object sender, AncestorChangedEventArgs e)

堆栈跟踪更深入，但我认为它不相关。
我的问题是:
1. 是什么原因导致的，我该如何解决？
2. 我怎样才能捕获这个异常以防止我的应用程序崩溃？ (它发生在我无权访问的系统线程中......)

Answer 1

_hwnd = BuildWindowCore(hwndParent);

if(_hwnd.Handle == IntPtr.Zero || !UnsafeNativeMethods.IsWindow(_hwnd))
{
     throw new InvalidOperationException(SR.Get(SRID.ChildWindowNotCreated));
}

这是 WPF source code 的特定部分抛出异常。 IsWindow 是直接调用 Win32 IsWindow功能。

我的猜测是您以某种方式从 BuildWindowCore 返回了 IntPtr.Zero 句柄。