Creating a blobclass for ATL

Environment: Configuration Files, INIs

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This class was written to make safearrays easy.

#ifndef _CFSAFEARVARIANT_
#define _CFSAFEARVARIANT_
/*
 *Author Frans Nagel
 *This class facilitates the use of the parray member of
 *CComVariant for storage of binary data. */

//Example of use:

int main(int argc, char* argv[])
{
  char * szText=  "this is the text\0and more";
  CSafeArrayVariant vSafeAr(szText,25);
  //vSafeAr now is a blob (VT_UI1|VT_ARRAY) that can be used
  //for COM calls.
  char * szRead  = (char*)vSafeAr;
  char * szExtra = szRead + 17;
  return 0;
}

class CSafeArrayVariant : public CComVariant
{
public:
  inline ~CSafeArrayVariant()
  {

  }
  inline void Clear()
  {
    if((vt & VT_ARRAY) && parray)
    {
      SafeArrayDestroy(parray);
      parray = 0;
    }
  }
  inline void ReadBytes(BYTE * pBytes,int nLength)
  {
    Clear();
    vt = VT_ARRAY|VT_UI1;
    BYTE * pBytes2 = 0;
    m_nLength = (nLength > 0) ? nLength : 0;
    parray = SafeArrayCreateVector(VT_UI1,1,m_nLength + 1);
    SafeArrayAccessData(parray,(void**)&pBytes2);
    memcpy(pBytes2,pBytes,m_nLength);
    pBytes2[m_nLength] = 0;
    SafeArrayUnaccessData(parray);
  }
  inline void ReadBytes(char* szText,int nLength)
  {
    BYTE * pBytes = (BYTE*)szText;
    m_nLength = nLength;
    ReadBytes(pBytes,nLength);
  }
  inline operator += (CSafeArrayVariant &var)
  {
    int nAddedLength = var.GetLength();
    if(nAddedLength)
    {
      int nNewLength = m_nLength + nAddedLength;
      BYTE * pBytes = (BYTE*)_alloca(nNewLength);
      if(m_nLength)
      memcpy(pBytes,(char*)(*this),m_nLength);
      memcpy(pBytes + m_nLength,(char*)var,nAddedLength);
      ReadBytes(pBytes,nNewLength);
    }
  }
  inline CSafeArrayVariant()
  {
    parray    = 0;
    m_nLength = 0;
  }
  inline CSafeArrayVariant(char * szBytes,int nLength)
  {
    ReadBytes(szBytes,nLength);
  }
  inline CSafeArrayVariant(const CComVariant& var)
  {
    parray   = 0;
    operator =(var);
  }


  inline operator = (VARIANT var)
  {
    m_nLength = 0;
    if(var.vt == (VT_ARRAY|VT_UI1))
    {
      long lBound,uBound;
      SafeArrayGetLBound(var.parray,1,&lBound);
      SafeArrayGetUBound(var.parray,1,&uBound);
      m_nLength = uBound - lBound;
    }
    CComVariant::operator =(var);
  }
  inline int GetLength()const \
  {
    return m_nLength;
  }
  inline operator char*()
  {
    //use GetLength() to make sure you read everything
    if(vt == (VT_ARRAY|VT_UI1))
    {
    BYTE * pBytes = 0;
    long lBound,uBound;
    SafeArrayGetLBound(parray,1,&lBound);
    SafeArrayGetUBound(parray,1,&uBound);
    m_nLength = uBound - lBound;
    SafeArrayAccessData(parray,(void**)&pBytes);
    char * szVal = (char*)pBytes;
    SafeArrayUnaccessData(parray);
    return szVal;
    }
    USES_CONVERSION;
    return W2A(bstrVal);
  }
protected:
int m_nLength;
};

#endif


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