Data Transfer, COM Enums, and Windows Controls

Listing 3 Implemenation of ListExchange_PutItems_Base()

/* /////////////////////////////////////////////////////////////
 * ...
 *
 * 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)
 *
 * ...
 * ////////////////////////////////////////////////////////// */

SInt32 ListExchange_PutItems_Base(
        HWND                    hwndList,
        LPUNKNOWN               punkEnumItems,
        UInt32                  flags,
        UInt32                  param,
        EnumeratorHandler const *enumerators,
        UInt32                  cEnumerators,
        ControlHandler const    *controls,
        UInt32                  cControls)
{
  HRESULT hr;

  _ASSERTE(IsWindow(hwndList));

  if( !(flags & SYLXF_RESETCONTENT) &&
      ( NULL == punkEnumItems ||
        NULL == enumerators ||
        0 == cEnumerators))
  {
    hr = E_INVALIDARG;
  }
  else if(!IsWindow(hwndList) ||
          0 == cControls ||
          NULL == controls)
  {
    hr = E_INVALIDARG;
  }
  else
  {
    LPUNKNOWN punkEnum  = NULL;
    UInt32    i;

    /* Find the window class */
    for(hr = E_FAIL, i = 0; FAILED(hr) && i < cControls; ++i)
    {
      if(IsWindowClass(hwndList, controls[i].className))
      {
        hr = S_OK;
        break;
      }
    }

    if(FAILED(hr))
    {
      ErrorInfo_SetDescW(L"Window not of recognised class");

      hr = E_INVALIDARG;
    }
    else
    {
      ControlHandler const  *control  = &controls[i];

      if(NULL == punkEnumItems)
      {
        /* Only want to clear the window */

        _ASSERTE((flags & SYLXF_RESETCONTENT) == SYLXF_RESETCONTENT);

        control->pfnReset(hwndList);
      }
      else
      {
        /* Find the interface */
        for(hr = E_NOINTERFACE, i = 0; i < cEnumerators; ++i)
        {
#ifdef __cplusplus
          hr = punkEnumItems->QueryInterface(
#else
          hr = punkEnumItems->lpVtbl->QueryInterface( punkEnumItems,
#endif /* __cplusplus */
                                enumerators[i].iid,
                                (LPPVoid)(&punkEnum));

          if(SUCCEEDED(hr))
          {
            break;
          }
        }

        if(FAILED(hr))
        {
          ErrorInfo_SetDescW(L"Enumerator not of recognised type");

          hr = E_INVALIDARG;
        }
        else
        {
          EnumeratorHandler const *enumerator = &enumerators[i];

          /* Erase the existing content */
          if((flags & SYLXF_RESETCONTENT) == SYLXF_RESETCONTENT)
          {
            control->pfnReset(hwndList);
          }

          /* Now enumerate over the sequence, inserting as we go. */
          for(hr = S_OK, enumerator->pfnReset(punkEnum); SUCCEEDED(hr); )
          {
            Enum2WndItem  item;
            LPVOID      value;

            hr  = enumerator->pfnNextItem(punkEnum, &item, &value);

            if(hr == S_OK)
            {
              /* Add to the control ... */
              hr = control->pfnPutItem(hwndList, value, flags);

              /* ... and release any resources from enumerator */
              enumerator->pfnClearItem(punkEnum, &item, value);
            }
            else if(hr == S_FALSE)
            {
              hr = S_OK;
              break;
            }
          }

#ifdef __cplusplus
          punkEnum->Release();
#else
          punkEnum->lpVtbl->Release(punkEnum);
#endif /* __cplusplus */
        }
      }
    }
  }

  return hr;
}