对一组C＃结构进行编组并在COM中使用它 - 什么是正确的编组属性

Question

我将面临以下问题将近一周：我有一个c＃结构数组，需要将其发送到COM应用程序。 但是当我调用COM方法时，我得到以下内容

错误：发生了System.Runtime.InteropServices.MarshalDirectiveException

附加信息：无法编组'参数＃5'：无效的托管/非托管类型组合（Int / UInt必须与SysInt或SysUInt配对）。

IDL文件使用C＃接口进行扩展/派生。

以下是IDL中定义的方法：

[helpstring("Method MyCallbackMehtod")]
    HRESULT MyRequestFinished(
        [in] long    callId,
        [in] unsigned int nrElemArray1,
        [in, size_is(nrElemArray1)] MyStruct ElemArray1[],
        [in] unsigned int nrElemArray2,
        [in, size_is(nrElemArray2)] MyStruct ElemArray2[]
);

c＃界面：

 [ComImport, Guid("xxxxxxxx-xxxx-xxxx-xxx-xxxxxxxxxx")]
    [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    public interface IMyInterface
    {

        void MyRequestFinished(
            [In] 
            long callId,

            [In] 
            uint nrElemArray1,

            [In,MarshalAs(UnmanagedType.LPArray,SizeParamIndex=1)] 
            IntPtr ElemArray1,

            [In]
            uint nrElemArray2,

            [In, MarshalAs(UnmanagedType.LPArray,SizeParamIndex = 3)]  
            IntPtr ElemArray2);
}

MyStruct的定义是：

[StructLayout(LayoutKind.Sequential,Pack=1)]
    public struct MyStruct
    {
        public double setValue;
        public double actualValue;
        [MarshalAs(UnmanagedType.I4)]
        public MyEnum myResult;
    }

    [ComVisible(true)]
    public enum MyEnum 
    {
        Val1,

        Val2,

        Val3
    }

调用COM方法的代码片段：

IntPtr pMyElemArray1  = IntPtr.Zero;
IntPtr pMyElemArray2 = IntPtr.Zero;

MyStruct[] MyElemArray1= GetArray1();
MyStruct[] MyElemArray2= GetArray2();

int lengthElemArray1= MyElemArray1.Length;
int lengthElemArray2= MyElemArray2.Length;

pMyElemArray1 = Marshal.AllocCoTaskMem(Marshal.SizeOf(MyElemArray1[0]) * lengthElemArray1);
pMyElem2 = Marshal.AllocCoTaskMem(Marshal.SizeOf(MyElemArray2[0]) * lengthElemArray2);

int rundef = (int)pMyElemArray1 ;
for (int i = 0; i < lengthElemArray1; i++)
{
     Marshal.StructureToPtr(MyElemArray1 [i], (IntPtr)rundef, false);
     rundef += Marshal.SizeOf(MyElemArray1[i]);
}

rundef = (int)pMyElemArray2;
for (int i = 0; i < lengthElemArray2; i++)
{
    Marshal.StructureToPtr(MyElemArray2[i], (IntPtr)rundef, false);
    rundef += Marshal.SizeOf(MyElemArray2[i]);
}

// Notify COM component
//here i get the error
  myComObject.MyRequestFinished(callId,
                       ((uint)lengthElemArray1),
                       pMyElemArray1,
                       ((uint)lengthElemArray2),
                       pMyElemArray2);
//....
}

Answer 1

LPArray不适用于IntPtr类型的参数。 尝试将参数类型更改为数组或删除MarshalAs属性。

void MyRequestFinished(
    [In]
    long callId,

    [In]
    uint nrElemArray1,

    [In, MarshalAs(UnmanagedType.LPArray, SizeParamIndex = 1)]
    MyStruct[] ElemArray1,

    [In]
    uint nrElemArray2,

    [In]  
    IntPtr ElemArray2);
}

就个人而言，我更喜欢传入数组而不是IntPtr，因为它会在调用站点产生更简单的逻辑。