Prototyping DirectShow filters in C#

#pragma once
#using <mscorlib.dll>
#using <MyBW.dll>

#include <vcclr.h>

class CCsSobel : public CTransformFilter
{

public:

    DECLARE_IUNKNOWN;
    static CUnknown * WINAPI CreateInstance(LPUNKNOWN punk, HRESULT *phr);

    // Overrriden from CTransformFilter base class
    HRESULT Transform(IMediaSample *pIn, IMediaSample *pOut);
    HRESULT CheckInputType(const CMediaType *mtIn);
    HRESULT CheckTransform(const CMediaType *mtIn, const CMediaType *mtOut);
    HRESULT DecideBufferSize(IMemAllocator *pAlloc, ALLOCATOR_PROPERTIES *pProperties);
    HRESULT GetMediaType(int iPosition, CMediaType *pMediaType);


private:

    // Constructor
    CCsSobel(TCHAR *tszName, LPUNKNOWN punk, HRESULT *phr);
	~CCsSobel();

    CCritSec m_CsSobelLock;         // Private play critical section

    gcroot< MyBW *> mySobel;
};