問題描述
將 C++ 函數指針設置為 C# 委託 (set C++ function pointer as C# delegate)
I have a unmanaged c++ application as COM client and a C# COM server. now i want COM server can invoke a c++ function.
C# :
[ClassInterface(ClassInterfaceType.AutoDual)]
public class SomeType
{
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
public delegate void DeleCallBack(string info);
public DeleCallBack CallBack;
public void SetCallBack(ref IntPtr ptr)
{
CallBack = (DeleCallBack)Marshal.GetDelegateForFunctionPointer(ptr, typeof(DeleCallBack));
}
}
C++:
HRESULT hr = E_FAIL;
CComPtr<WindowsFormsApplicationVC9::_SomeType> spTmp;
hr = spTmp.CoCreateInstance(__uuidof(WindowsFormsApplicationVC9::SomeType));
if (SUCCEEDED(hr))
{
spTmp->SetCallBack(OnCallBack);
}
void OnCallBack(BSTR info)
{
// c++ function call...;
}
I'm not sure it is the right way to just pass the OnCallBack function pointer to SetCallBack. I noticed that some sample of calling GetDelegateForFunctionPointer should GetProcessAddress to get the function pointer address, but i can't do that since there are may be different c++ COM client with different function name.
any suggestion?
參考解法
方法 1:
One way to do it is to expose your C++ functions via __declspec(dllexport), then simply write P/Invoke for those functions. Now you can use those P/Invoke functions as delegates.
Deep down this is essentially the GetProcAddress approach but the C# compiler makes it syntactically nicer for you.