小编Mik*_*e G的帖子

我想在我的 WPF 应用程序中托管一个外部进程的窗口。我是这样推导的HwndHost：

    class HwndHostEx : HwndHost
    {
        [DllImport("user32.dll")]
        static extern IntPtr SetParent(IntPtr hWndChild, IntPtr hWndNewParent);

        private IntPtr ChildHandle = IntPtr.Zero;

        public HwndHostEx(IntPtr handle)
        {
            this.ChildHandle = handle;
        }

        protected override System.Runtime.InteropServices.HandleRef BuildWindowCore(System.Runtime.InteropServices.HandleRef hwndParent)
        {
            HandleRef href = new HandleRef();

            if (ChildHandle != IntPtr.Zero)
            {
                SetParent(this.ChildHandle, hwndParent.Handle);
                href = new HandleRef(this, this.ChildHandle);
            }

            return href;
        }

        protected override void DestroyWindowCore(System.Runtime.InteropServices.HandleRef hwnd)
        {

        }
    }

并像这样使用它：

 HwndHostEx host = new HwndHostEx(handle);
 this.PART_Host.Child = host;

handle我想托管的外部窗口的句柄在哪里，是PART_Host我的 WPF …

C代码：

// Device description structure
struct DeviceInfo
{
  unsigned short deviceID;
  unsigned short productID;
  unsigned short versionNumber;
  wchar_t* deviceName;
}; 

void __cdecl GetAttachedDevices(
  int* count,
  DeviceInfo* deviceInfoList
);

以及使用此 C DLL 的 PInvoke C# 代码：

    public struct DeviceInfo
    {
        public ushort deviceID;
        public ushort productID;
        public ushort versionNumber;
        public IntPtr deviceName;
    }; 

    [DllImport("Native.dll", CallingConvention=CallingConvention.Cdecl)]
    public static extern void GetAttachedDevices(ref int count, ref DeviceInfo deviceInfoList);

当我使用这个 C# 代码时：

    int count = 0;
    DeviceInfo dev = new DeviceInfo();

    GetAttachedDevices(ref count, ref dev); …

这是我的C代码:

    LIBRARY_API bool __cdecl Initialize(void (*FirstScanForDevicesDoneFunc)(void));

这是使用此DLL的C#PINvoke代码:

    [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
    public delegate void FirstScanForDevicesDoneFunc();

    [DllImport("Native.dll", CallingConvention=CallingConvention.Cdecl)]
    public static extern bool Initialize(FirstScanForDevicesDoneFunc);

当我这样调用这个方法时:

    static public void Init() {
        Initialize(FirstScanForDevicesDone);
    }

    static public void FirstScanForDevicesDone() {
        //do something
    }

在Init()回调结束时,我得到NullReferenceException.所以我使用Thread来保持它并且一切正常,但我对这个解决方案不满意:

    static public bool Working = true;

    static public void Init() {
        new Thread(() =>
        {
            Thread.CurrentThread.IsBackground = true;

            Initialize(FirstScanForDevicesDone);
            while (Working)
            {
                Thread.Sleep(1000);
            }
        }).Start();
    }

是否有更复杂的方法来保持这种工作？