Data Transfer, COM Enums, and Windows Controls

Listing 4

// Listing 4: Implementation of enumerator handlers

/* /////////////////////////////////////////////////////////////
 * ...
 *
 * Extract from MOCtlFns.c
 *
 * Copyright (C) 1998-2003, Synesis Software Pty Ltd.
 * (Licensed under the Synesis Software Standard Public License:
 *  http://www.synesis.com.au/licenses/ssspl.html)
 *
 * ...
 * ////////////////////////////////////////////////////////// */

/* IEnumXXXX */

HRESULT EnumXXXX_Reset(LPVOID itf)
{
  LPENUMSTRING  pen = (LPENUMSTRING)itf;

  return pen->lpVtbl->Reset(pen);
}

/* IEnumString */

HRESULT EnumString_NextItem(LPVOID itf, LPEnum2WndItem pitem, LPVOID *pvalue)
{
  LPENUMSTRING  pen = (LPENUMSTRING)itf;
  HRESULT       hr  = pen->lpVtbl->Next(pen, 1, &pitem->olestr, NULL);

  if(hr == S_OK)
  {
    *pvalue = pitem->olestr;
  }

  return hr;
}

void EnumString_ClearItem(LPVOID pen, LPEnum2WndItem pitem, LPVOID value)
{
  CoTaskMemFree(pitem->olestr);
}

/* IEnumBSTR */

HRESULT EnumBSTR_NextItem(LPVOID itf, LPEnum2WndItem pitem, LPVOID *pvalue)
{
  LPENUMBSTR  pen = (LPENUMBSTR)itf;
  HRESULT     hr  = pen->lpVtbl->Next(pen, 1, &pitem->bstr, NULL);

  if(hr == S_OK)
  {
    *pvalue = pitem->bstr;
  }

  return hr;
}

void EnumBSTR_ClearItem(LPVOID pen, LPEnum2WndItem pitem, LPVOID value)
{
  SysFreeString(pitem->bstr);
}

/* IEnumVARIANT */

HRESULT EnumVARIANT_NextItem(LPVOID itf, LPEnum2WndItem pitem, LPVOID *pvalue)
{
  LPENUMVARIANT pen = (LPENUMVARIANT)itf;
  HRESULT       hr  = pen->lpVtbl->Next(pen, 1, &pitem->var, NULL);

  if(hr == S_OK)
  {
    hr = VariantChangeType(&pitem->var, &pitem->var, VARIANT_ALPHABOOL, VT_BSTR);

    if(SUCCEEDED(hr))
    {
      *pvalue = pitem->var.bstrVal;
    }
    else
    {
      VariantClear(&pitem->var);
    }
  }

  return hr;
}

void EnumVARIANT_ClearItem(LPVOID pen, LPEnum2WndItem pitem, LPVOID value)
{
  VariantClear(&pitem->var);
}

/* IEnumGUID */

HRESULT EnumGUID_NextItem(LPVOID itf, LPEnum2WndItem pitem, LPVOID *pvalue)
{
  LPENUMGUID  pen = (LPENUMGUID)itf;
  HRESULT     hr  = pen->lpVtbl->Next(pen, 1, &pitem->guid, NULL);

  if(hr == S_OK)
  {
    hr = StringFromCLSID(&pitem->guid, SyCastRaw(LPOLESTR*, pvalue));
  }

  return hr;
}

void EnumGUID_ClearItem(LPVOID pen, LPEnum2WndItem pitem, LPVOID value)
{
  OleString_Destroy(SyCastRaw(LPOLESTR*, &value));
}

/* IEnumUnknown */

HRESULT EnumUnknown_NextItem(LPVOID itf, LPEnum2WndItem pitem, LPVOID *pvalue)
{
  LPENUMUNKNOWN pen = (LPENUMUNKNOWN)itf;
  HRESULT       hr  = pen->lpVtbl->Next(pen, 1, &pitem->punk, NULL);

  if(hr == S_OK)
  {
    /* Use the VariantChangeType() mechanism to get the value property of 
     * the object.
     */
    VARIANT dest;

    VariantInit(&dest);

    hr = Dispatch_GetProperty(pitem->punk, DISPID_VALUE, &dest);

    if(SUCCEEDED(hr))
    {
      hr = VariantChangeType(&dest, &dest, VARIANT_ALPHABOOL, VT_BSTR);

      if(SUCCEEDED(hr))
      {
        *pvalue = OleString_Dup(dest.bstrVal);
      }

      VariantClear(&dest);
    }

    if(NULL != pitem->punk)
    {
      pitem->punk->lpVtbl->Release(pitem->punk);
    }
  }

  return hr;
}

void EnumUnknown_ClearItem(LPVOID pen, LPEnum2WndItem pitem, LPVOID value)
{
  OleString_Destroy(SyCastRaw(LPOLESTR*, &value));
}