/*
 * OleDND.h --
 *
 *    This file implements the windows portion of the drag&drop mechanish
 *    for the tk toolkit. The protocol in use under windows is the
 *    OLE protocol. Based on code wrote by Gordon Chafee.
 *
 * This software is copyrighted by:
 * George Petasis, National Centre for Scientific Research "Demokritos",
 * Aghia Paraskevi, Athens, Greece.
 * e-mail: petasis@iit.demokritos.gr
 * Laurent Riesterer, Rennes, France.
 * e-mail: laurent.riesterer@free.fr
 *
 * The following terms apply to all files associated
 * with the software unless explicitly disclaimed in individual files.
 *
 * The authors hereby grant permission to use, copy, modify, distribute,
 * and license this software and its documentation for any purpose, provided
 * that existing copyright notices are retained in all copies and that this
 * notice is included verbatim in any distributions. No written agreement,
 * license, or royalty fee is required for any of the authorized uses.
 * Modifications to this software may be copyrighted by their authors
 * and need not follow the licensing terms described here, provided that
 * the new terms are clearly indicated on the first page of each file where
 * they apply.
 *
 * IN NO EVENT SHALL THE AUTHORS OR DISTRIBUTORS BE LIABLE TO ANY PARTY
 * FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
 * ARISING OUT OF THE USE OF THIS SOFTWARE, ITS DOCUMENTATION, OR ANY
 * DERIVATIVES THEREOF, EVEN IF THE AUTHORS HAVE BEEN ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 * THE AUTHORS AND DISTRIBUTORS SPECIFICALLY DISCLAIM ANY WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, AND NON-INFRINGEMENT.  THIS SOFTWARE
 * IS PROVIDED ON AN "AS IS" BASIS, AND THE AUTHORS AND DISTRIBUTORS HAVE
 * NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR
 * MODIFICATIONS.
 */

#ifndef _OLE_DND_H
#define _OLE_DND_H

#include <windows.h>
#include <ole2.h>
#include <shlobj.h>
#include <io.h>
#include <fcntl.h>
#include <share.h>
#include <sys/stat.h>
#include <wchar.h>

#ifdef DND_ENABLE_DROP_TARGET_HELPER
#include <atlbase.h>
#include <shlobj.h>     /* for IDropTargetHelper */
#include <shlguid.h>
/* We need this declaration for CComPtr, which uses __uuidof() */
struct __declspec(uuid("{4657278B-411B-11d2-839A-00C04FD918D0}"))
  IDropTargetHelper;
#endif /* DND_ENABLE_DROP_TARGET_HELPER */

#include <tcl.h>
#include <tk.h>
#include <tkPlatDecls.h>

#define TkDND_TkWin(x) \
  (Tk_NameToWindow(interp, Tcl_GetString(x), Tk_MainWindow(interp)))

#define TkDND_Eval(objc) {\
  for (i=0; i<objc; ++i) Tcl_IncrRefCount(objv[i]);\
  if (Tcl_EvalObjv(interp, objc, objv, TCL_EVAL_GLOBAL) != TCL_OK) \
      Tk_BackgroundError(interp); \
  for (i=0; i<objc; ++i) Tcl_DecrRefCount(objv[i]);}

#define TkDND_Status_Eval(objc) {\
  for (i=0; i<objc; ++i) Tcl_IncrRefCount(objv[i]);\
  status = Tcl_EvalObjv(interp, objc, objv, TCL_EVAL_GLOBAL);\
  if (status != TCL_OK) Tk_BackgroundError(interp); \
  for (i=0; i<objc; ++i) Tcl_DecrRefCount(objv[i]);}


/*****************************************************************************
 * Windows Clipboard formats.
 ****************************************************************************/
#define STRING_(s) s,#s
typedef struct {
  UINT  cfFormat;
  char *name;
} CLIP_FORMAT_STRING_TABLE;

static CLIP_FORMAT_STRING_TABLE ClipboardFormatBook[] = {
  STRING_(CF_TEXT),
  STRING_(CF_BITMAP),
  STRING_(CF_METAFILEPICT),
  STRING_(CF_SYLK),
  STRING_(CF_DIF),
  STRING_(CF_TIFF),
  STRING_(CF_OEMTEXT),
  STRING_(CF_DIB),
  STRING_(CF_PALETTE),
  STRING_(CF_PENDATA),
  STRING_(CF_RIFF),
  STRING_(CF_WAVE),
  STRING_(CF_UNICODETEXT),
  STRING_(CF_ENHMETAFILE),
  STRING_(CF_HDROP),
  STRING_(CF_LOCALE),
  STRING_(CF_DIBV5),
  STRING_(CF_OWNERDISPLAY),
  STRING_(CF_DSPTEXT),
  STRING_(CF_DSPBITMAP),
  STRING_(CF_DSPMETAFILEPICT),
  STRING_(CF_DSPENHMETAFILE),
  STRING_(CF_GDIOBJFIRST),
  STRING_(CF_PRIVATEFIRST),
  0, 0
}; /* ClipboardFormatBook */

/*****************************************************************************
 * Data Object Class.
 ****************************************************************************/

// Helper function to perform a "deep" copy of a FORMATETC
static void DeepCopyFormatEtc(FORMATETC *dest, FORMATETC *source) {
  // copy the source FORMATETC into dest
  *dest = *source;
  if(source->ptd) {
    // allocate memory for the DVTARGETDEVICE if necessary
    dest->ptd = (DVTARGETDEVICE*)CoTaskMemAlloc(sizeof(DVTARGETDEVICE));
    // copy the contents of the source DVTARGETDEVICE into dest->ptd
    *(dest->ptd) = *(source->ptd);
  }
}; /* DeepCopyFormatEtc */

HRESULT CreateEnumFormatEtc(UINT nNumFormats, FORMATETC *pFormatEtc,
                            IEnumFORMATETC **ppEnumFormatEtc);

class TkDND_FormatEtc : public IEnumFORMATETC {
public:

    // IUnknown members
    HRESULT __stdcall QueryInterface(REFIID iid, void ** ppvObject) {
      // check to see what interface has been requested
      if (iid == IID_IEnumFORMATETC || iid == IID_IUnknown) {
        AddRef();
        *ppvObject = this;
        return S_OK;
      } else {
        *ppvObject = 0;
        return E_NOINTERFACE;
      }
    }; /* QueryInterface */

    ULONG __stdcall AddRef(void) {
      // increment object reference count
      return InterlockedIncrement(&m_lRefCount);
    }; /* AddRef */

    ULONG __stdcall Release (void) {
      // decrement object reference count
      LONG count = InterlockedDecrement(&m_lRefCount);
      if (count == 0) {
        delete this;
        return 0;
      } else {
        return count;
      }
    }; /* Release */

    // IEnumFormatEtc members
    HRESULT __stdcall Next(ULONG celt, FORMATETC *pFormatEtc,
                           ULONG *pceltFetched) {
      ULONG copied  = 0;
      // validate arguments
      if(celt == 0 || pFormatEtc == 0) return E_INVALIDARG;
      // copy FORMATETC structures into caller's buffer
      while (m_nIndex < m_nNumFormats && copied < celt) {
        DeepCopyFormatEtc(&pFormatEtc[copied], &m_pFormatEtc[m_nIndex]);
        copied++; m_nIndex++;
      }
      // store result
      if (pceltFetched != 0) *pceltFetched = copied;
      // did we copy all that was requested?
      return (copied == celt) ? S_OK : S_FALSE;
    }; /* Next */

    HRESULT __stdcall Skip(ULONG celt) {
      m_nIndex += celt;
      return (m_nIndex <= m_nNumFormats) ? S_OK : S_FALSE;
    }; /* Skip */

    HRESULT __stdcall Reset(void) {
      m_nIndex = 0;
      return S_OK;
    }; /* Reset */

    HRESULT __stdcall Clone(IEnumFORMATETC ** ppEnumFormatEtc) {
      HRESULT hResult;
      // make a duplicate enumerator
      hResult = CreateEnumFormatEtc(m_nNumFormats, m_pFormatEtc,
                                    ppEnumFormatEtc);
      if (hResult == S_OK) {
        // manually set the index state
        ((TkDND_FormatEtc *) *ppEnumFormatEtc)->m_nIndex = m_nIndex;
      }
      return hResult;
    }; /* Clone */

    // Construction / Destruction
    TkDND_FormatEtc(FORMATETC *pFormatEtc, int nNumFormats) {
      m_lRefCount   = 1;
      m_nIndex      = 0;
      m_nNumFormats = nNumFormats;
      m_pFormatEtc  = new FORMATETC[nNumFormats];

      // copy the FORMATETC structures
      for (int i = 0; i < nNumFormats; i++) {
        DeepCopyFormatEtc(&m_pFormatEtc[i], &pFormatEtc[i]);
      }
    }; /* TkDND_FormatEtc */

    ~TkDND_FormatEtc() {
       if (m_pFormatEtc) {
         for(ULONG i = 0; i < m_nNumFormats; i++) {
           if(m_pFormatEtc[i].ptd) CoTaskMemFree(m_pFormatEtc[i].ptd);
         }
         delete[] m_pFormatEtc;
       }
    }; /* ~TkDND_FormatEtc */

private:
    LONG  m_lRefCount;        // Reference count for this COM interface
    ULONG m_nIndex;           // current enumerator index
    ULONG m_nNumFormats;      // number of FORMATETC members
    FORMATETC * m_pFormatEtc; // array of FORMATETC objects
}; /* TkDND_FormatEtc */

// "Drop-in" replacement for SHCreateStdEnumFmtEtc.
HRESULT CreateEnumFormatEtc(UINT nNumFormats, FORMATETC *pFormatEtc,
                            IEnumFORMATETC **ppEnumFormatEtc) {
  if(nNumFormats==0 || pFormatEtc==0 || ppEnumFormatEtc==0) return E_INVALIDARG;
  *ppEnumFormatEtc = new TkDND_FormatEtc(pFormatEtc, nNumFormats);
  return (*ppEnumFormatEtc) ? S_OK : E_OUTOFMEMORY;
}; /* CreateEnumFormatEtc */


class TkDND_DataObject : public IDataObject {
public:

    // IUnknown members
    HRESULT __stdcall QueryInterface(REFIID iid, void ** ppvObject) {
      // check to see what interface has been requested
      if (iid == IID_IDataObject || iid == IID_IUnknown) {
        AddRef();
        *ppvObject = this;
        return S_OK;
      } else {
        *ppvObject = 0;
        return E_NOINTERFACE;
      }
    }; /* QueryInterface */

    ULONG __stdcall AddRef(void) {
      // increment object reference count
      return InterlockedIncrement(&m_lRefCount);
    }; /* AddRef */

    ULONG __stdcall Release(void) {
      // decrement object reference count
      LONG count = InterlockedDecrement(&m_lRefCount);
      if (count == 0) {
        delete this; return 0;
      } else {
         return count;
      }
    }; /* Release */

    // IDataObject members
    HRESULT __stdcall GetData(FORMATETC *pFormatEtc,  STGMEDIUM *pMedium) {
      int idx;
      // try to match the specified FORMATETC with one of our supported formats
      if ((idx = LookupFormatEtc(pFormatEtc)) == -1) return DV_E_FORMATETC;

      // found a match - transfer data into supplied storage medium
      pMedium->tymed           = m_pFormatEtc[idx].tymed;
      pMedium->pUnkForRelease  = 0;

      // copy the data into the caller's storage medium
      switch(m_pFormatEtc[idx].tymed) {
        case TYMED_HGLOBAL:
          pMedium->hGlobal = DupGlobalMem(m_pStgMedium[idx].hGlobal);
          break;
        default:
          return DV_E_FORMATETC;
      }
      return S_OK;
    }; /* GetData */

    HRESULT __stdcall GetDataHere(FORMATETC *pFormatEtc,  STGMEDIUM *pmedium) {
      return DATA_E_FORMATETC;
    }; /* GetDataHere */


    HRESULT __stdcall QueryGetData(FORMATETC *pFormatEtc) {
      return (LookupFormatEtc(pFormatEtc) == -1) ? DV_E_FORMATETC : S_OK;
    };

    HRESULT __stdcall GetCanonicalFormatEtc(FORMATETC *pFormatEct,
                      FORMATETC *pFormatEtcOut) {
      // Apparently we have to set this field to NULL even though we don't do
      // anything else.
      pFormatEtcOut->ptd = NULL;
      return E_NOTIMPL;
    }; /* GetCanonicalFormatEtc */

    HRESULT __stdcall SetData(FORMATETC *pFormatEtc, STGMEDIUM *pMedium,
                              BOOL fRelease) {
      return E_NOTIMPL;
    }; /* SetData */

    HRESULT __stdcall EnumFormatEtc(DWORD dwDirection,
                                    IEnumFORMATETC **ppEnumFormatEtc) {
      // only the get direction is supported for OLE
      if(dwDirection == DATADIR_GET) {
        // for Win2k+ you can use the SHCreateStdEnumFmtEtc API call, however
        // to support all Windows platforms we need to implement
        // IEnumFormatEtc ourselves.
        return CreateEnumFormatEtc(m_nNumFormats,m_pFormatEtc,ppEnumFormatEtc);
      } else {
        // the direction specified is not supported for drag+drop
        return E_NOTIMPL;
      }
    }; /* EnumFormatEtc */

    HRESULT __stdcall DAdvise(FORMATETC *pFormatEtc,  DWORD advf,
                              IAdviseSink *, DWORD *) {
      return OLE_E_ADVISENOTSUPPORTED;
    }; /* DAdvise */

    HRESULT __stdcall DUnadvise(DWORD dwConnection) {
      return OLE_E_ADVISENOTSUPPORTED;
    }; /* DUnadvise */

    HRESULT __stdcall EnumDAdvise(IEnumSTATDATA **ppEnumAdvise) {
      return OLE_E_ADVISENOTSUPPORTED;
    }; /* EnumDAdvise */;

    // Constructor / Destructor
    TkDND_DataObject(FORMATETC *fmtetc, STGMEDIUM *stgmed, int count) {
      // reference count must ALWAYS start at 1
      m_lRefCount    = 1;
      m_nNumFormats  = count;

      m_pFormatEtc   = new FORMATETC[count];
      m_pStgMedium   = new STGMEDIUM[count];

      for(int i = 0; i < count; i++)
      {
          m_pFormatEtc[i] = fmtetc[i];
          m_pStgMedium[i] = stgmed[i];
      }
      currentFormat = 0;
    }; /* TkDND_DataObject */

    ~TkDND_DataObject() {
      // cleanup
      if(m_pFormatEtc) delete[] m_pFormatEtc;
      if(m_pStgMedium) delete[] m_pStgMedium;
    }; /* ~TkDND_DataObject */

    // Custom functions.
    UINT GetCurrentFormat(void) {
      return currentFormat;
    }; /* GetCurrentFormat */

    char *GetCurrentFormatName(void) {
      for (int i = 0; ClipboardFormatBook[i].name != 0; i++) {
        if (ClipboardFormatBook[i].cfFormat == currentFormat)
                     return ClipboardFormatBook[i].name;
      }
      GetClipboardFormatName((CLIPFORMAT) currentFormat, szTempStr, 78);
      return szTempStr;
    }; /* GetCurrentFormatName */


private:

    // any private members and functions
    LONG       m_lRefCount;
    FORMATETC *m_pFormatEtc;
    STGMEDIUM *m_pStgMedium;
    LONG       m_nNumFormats;
    UINT       currentFormat;

    char szTempStr[80];

    int LookupFormatEtc(FORMATETC *pFormatEtc) {
      // check each of our formats in turn to see if one matches
      for(int i = 0; i < m_nNumFormats; i++) {
        // The AND operator is used here because the FORMATETC::tymed member
        // is actually a bit-flag which can contain more than one value.
        // For example, the caller of QueryGetData could quite legitimetly
        // specify a FORMATETC::tymed value of (TYMED_HGLOBAL | TYMED_ISTREAM)
        // , which basically means "Do you support HGLOBAL or IStream?".
        if ((m_pFormatEtc[i].tymed    &  pFormatEtc->tymed)   &&
             m_pFormatEtc[i].cfFormat == pFormatEtc->cfFormat &&
             m_pFormatEtc[i].dwAspect == pFormatEtc->dwAspect) {
             currentFormat = m_pFormatEtc[i].cfFormat;
             // return index of stored format
             return i;
        }
      }
      // error, format not found
      return -1;
    }; /* LookupFormatEtc */

    HGLOBAL DupGlobalMem(HGLOBAL hMem) {
      DWORD   len    = GlobalSize(hMem);
      PVOID   source = GlobalLock(hMem);
      PVOID   dest   = GlobalAlloc(GMEM_FIXED, len);
      memcpy(dest, source, len);
      GlobalUnlock(hMem);
      return dest;
    }; /* DupGlobalMem */

}; /* TkDND_DataObject */


/*****************************************************************************
 * Drop Target Related Class.
 ****************************************************************************/
class TkDND_DropTarget;
typedef class TkDND_DropTarget *PTDropTarget;
class TkDND_DropTarget: public IDropTarget {
  private:
    LONG                 m_lRefCount; /* Reference count */
    Tcl_Interp          *interp;
    Tk_Window            tkwin;
    char                 szTempStr[MAX_PATH];

    const char * FormatName(UINT cfFormat) {
      for (int i = 0; ClipboardFormatBook[i].name != 0; i++) {
        if (ClipboardFormatBook[i].cfFormat == cfFormat)
                     return ClipboardFormatBook[i].name;
      }
      GetClipboardFormatName((CLIPFORMAT) cfFormat, szTempStr, MAX_PATH - 2);
      return szTempStr;
    }; /* FormatName */

  public:
    TkDND_DropTarget(Tcl_Interp *_interp, Tk_Window _tkwin) :
      interp(_interp), tkwin(_tkwin), m_lRefCount(1) {
    }; /* TkDND_DropTarget */

    ~TkDND_DropTarget(void) {
   }; /* ~TkDND_DropTarget */

    /* IUnknown interface members */
    HRESULT __stdcall QueryInterface(REFIID iid, void ** ppvObject) {
      // check to see what interface has been requested
      if (iid == IID_IEnumFORMATETC || iid == IID_IUnknown) {
        AddRef();
        *ppvObject = this;
        return S_OK;
      } else {
        *ppvObject = 0;
        return E_NOINTERFACE;
      }
    }; /* QueryInterface */

    ULONG __stdcall AddRef(void) {
      // increment object reference count
      return InterlockedIncrement(&m_lRefCount);
    }; /* AddRef */

    ULONG __stdcall Release(void) {
      // decrement object reference count
      LONG count = InterlockedDecrement(&m_lRefCount);
      if (count == 0) {
        delete this; return 0;
      } else {
        return count;
      }
    }; /* Release */

    /* IDropTarget interface members */

    STDMETHODIMP DragEnter(IDataObject *pDataObject, DWORD grfKeyState,
                           POINTL pt, DWORD *pdwEffect) {
      // We want to get:
      //   a) The types supported by the drag source.
      //   b) The actions supported by the drag source.
      //   c) The state of the keyboard modifier keys.
      // And we must return:
      //   a) The prefered action.

      IEnumFORMATETC *pEF;
      FORMATETC fetc;
      char tmp[64];
      Tcl_Obj *typelist    = Tcl_NewListObj(0, NULL), *element,
              *actionlist  = Tcl_NewListObj(0, NULL), *objv[8],
              *pressedkeys = Tcl_NewListObj(0, NULL), *result,
              *codelist    = Tcl_NewListObj(0, NULL);
      int i, status, index;
      static char *DropActions[] = {
        "copy", "move", "link", "ask",  "private", "refuse_drop",
        "default",
        (char *) NULL
      };
      enum dropactions {
        ActionCopy, ActionMove, ActionLink, ActionAsk, ActionPrivate,
        refuse_drop, ActionDefault
      };

      // Get the types supported by the drag source.
      if (pDataObject->EnumFormatEtc(DATADIR_GET, &pEF) == S_OK) {
        while (pEF->Next(1, &fetc, NULL) == S_OK) {
          if (pDataObject->QueryGetData(&fetc) == S_OK) {
            /* Get the format name from windows */
            element = Tcl_NewStringObj(FormatName(fetc.cfFormat), -1);
            Tcl_ListObjAppendElement(NULL, typelist, element);
            /* Store the numeric code of the format */
            sprintf(tmp, "0x%08x", fetc.cfFormat);
            element = Tcl_NewStringObj(tmp, -1);
            Tcl_ListObjAppendElement(NULL, codelist, element);
          }; // if (pIDataSource->QueryGetData(&fetc) == S_OK)
        }; // while (pEF->Next(1, &fetc, NULL) == S_OK)
      }; // if (pIDataSource->EnumFormatEtc(DATADIR_GET, &pEF) == S_OK)

      // Get the state of the keyboard modifier keys.
      // MK_CONTROL, MK_SHIFT, MK_ALT, MK_RBUTTON, MK_LBUTTON
      if (grfKeyState & MK_CONTROL)
        Tcl_ListObjAppendElement(NULL,pressedkeys,Tcl_NewStringObj("ctrl", -1));
      if (grfKeyState & MK_SHIFT)
        Tcl_ListObjAppendElement(NULL,pressedkeys,Tcl_NewStringObj("shift",-1));
      if (grfKeyState & MK_ALT)
        Tcl_ListObjAppendElement(NULL,pressedkeys,Tcl_NewStringObj("alt", -1));
      if (grfKeyState & MK_RBUTTON)
        Tcl_ListObjAppendElement(NULL,pressedkeys,Tcl_NewStringObj("3", -1));
      if (grfKeyState & MK_MBUTTON)
        Tcl_ListObjAppendElement(NULL,pressedkeys,Tcl_NewStringObj("2", -1));
      if (grfKeyState & MK_LBUTTON)
        Tcl_ListObjAppendElement(NULL,pressedkeys,Tcl_NewStringObj("1", -1));

      // Get the actions supported by the drag source.
      // DROPEFFECT_COPY, DROPEFFECT_MOVE, DROPEFFECT_LINK
      if (*pdwEffect & DROPEFFECT_COPY)
        Tcl_ListObjAppendElement(NULL,actionlist,Tcl_NewStringObj("copy", -1));
      if (*pdwEffect & DROPEFFECT_MOVE)
        Tcl_ListObjAppendElement(NULL,actionlist,Tcl_NewStringObj("move", -1));
      if (*pdwEffect & DROPEFFECT_LINK)
        Tcl_ListObjAppendElement(NULL,actionlist,Tcl_NewStringObj("link", -1));

      // We are ready to pass the info to the Tcl level, and get the desired
      // action.
      objv[0] = Tcl_NewStringObj("tkdnd::olednd::_HandleDragEnter", -1);
      objv[1] = Tcl_NewStringObj(Tk_PathName(tkwin), -1);
      objv[2] = typelist;
      objv[3] = actionlist;
      objv[4] = pressedkeys;
      objv[5] = Tcl_NewLongObj(pt.x);
      objv[6] = Tcl_NewLongObj(pt.y);
      objv[7] = codelist;
      TkDND_Status_Eval(8);
      *pdwEffect = DROPEFFECT_NONE;
      if (status == TCL_OK) {
        /* Get the returned action... */
        result = Tcl_GetObjResult(interp); Tcl_IncrRefCount(result);
        status = Tcl_GetIndexFromObj(interp, result, (const char **)DropActions,
                                     "dropactions", 0, &index);
        Tcl_DecrRefCount(result);
        if (status != TCL_OK) index = refuse_drop;
      }
      switch ((enum dropactions) index) {
        case ActionCopy:    *pdwEffect = DROPEFFECT_COPY; break;
        case ActionMove:    *pdwEffect = DROPEFFECT_MOVE; break;
        case ActionLink:    *pdwEffect = DROPEFFECT_LINK; break;
        case ActionAsk:     *pdwEffect = DROPEFFECT_NONE; break;
        case ActionPrivate: *pdwEffect = DROPEFFECT_NONE; break;
        case ActionDefault: *pdwEffect = DROPEFFECT_COPY; break;
        case refuse_drop:   *pdwEffect = DROPEFFECT_NONE; /* Refuse drop. */
      }
      return S_OK;
    }; /* DragEnter */

    STDMETHODIMP DragOver(DWORD grfKeyState, POINTL pt, DWORD *pdwEffect) {
      Tcl_Obj *objv[5], *pressedkeys = Tcl_NewListObj(0, NULL), *result;
      int i, status, index;
      static char *DropActions[] = {
        "copy", "move", "link", "ask",  "private", "refuse_drop",
        "default",
        (char *) NULL
      };
      enum dropactions {
        ActionCopy, ActionMove, ActionLink, ActionAsk, ActionPrivate,
        refuse_drop, ActionDefault
      };

      // Get the state of the keyboard modifier keys.
      // MK_CONTROL, MK_SHIFT, MK_ALT, MK_RBUTTON, MK_LBUTTON
      if (grfKeyState & MK_CONTROL)
        Tcl_ListObjAppendElement(NULL,pressedkeys,Tcl_NewStringObj("ctrl", -1));
      if (grfKeyState & MK_SHIFT)
        Tcl_ListObjAppendElement(NULL,pressedkeys,Tcl_NewStringObj("shift",-1));
      if (grfKeyState & MK_ALT)
        Tcl_ListObjAppendElement(NULL,pressedkeys,Tcl_NewStringObj("alt", -1));
      if (grfKeyState & MK_RBUTTON)
        Tcl_ListObjAppendElement(NULL,pressedkeys,Tcl_NewStringObj("3", -1));
      if (grfKeyState & MK_MBUTTON)
        Tcl_ListObjAppendElement(NULL,pressedkeys,Tcl_NewStringObj("2", -1));
      if (grfKeyState & MK_LBUTTON)
        Tcl_ListObjAppendElement(NULL,pressedkeys,Tcl_NewStringObj("1", -1));

      // We are ready to pass the info to the Tcl level, and get the desired
      // action.
      objv[0] = Tcl_NewStringObj("tkdnd::olednd::_HandleDragOver", -1);
      objv[1] = Tcl_NewStringObj(Tk_PathName(tkwin), -1);
      objv[2] = pressedkeys;
      objv[3] = Tcl_NewLongObj(pt.x);
      objv[4] = Tcl_NewLongObj(pt.y);
      TkDND_Status_Eval(5);
      *pdwEffect = DROPEFFECT_NONE;
      if (status == TCL_OK) {
        /* Get the returned action... */
        result = Tcl_GetObjResult(interp); Tcl_IncrRefCount(result);
        status = Tcl_GetIndexFromObj(interp, result, (const char **)DropActions,
                                     "dropactions", 0, &index);
        Tcl_DecrRefCount(result);
        if (status != TCL_OK) index = refuse_drop;
      }
      switch ((enum dropactions) index) {
        case ActionCopy:    *pdwEffect = DROPEFFECT_COPY; break;
        case ActionMove:    *pdwEffect = DROPEFFECT_MOVE; break;
        case ActionLink:    *pdwEffect = DROPEFFECT_LINK; break;
        case ActionAsk:     *pdwEffect = DROPEFFECT_NONE; break;
        case ActionPrivate: *pdwEffect = DROPEFFECT_NONE; break;
        case ActionDefault: *pdwEffect = DROPEFFECT_COPY; break;
        case refuse_drop:   *pdwEffect = DROPEFFECT_NONE; /* Refuse drop. */
      }
      return S_OK;
    }; /* DragOver */

    STDMETHODIMP DragLeave(void) {
      Tcl_Obj *objv[2];
      int i;
      objv[0] = Tcl_NewStringObj("tkdnd::olednd::_HandleDragLeave", -1);
      objv[1] = Tcl_NewStringObj(Tk_PathName(tkwin), -1);
      TkDND_Eval(2);
      return S_OK;
    }; /* DragLeave */

    STDMETHODIMP Drop(IDataObject *pDataObject, DWORD grfKeyState,
                      POINTL pt, DWORD *pdwEffect) {
      Tcl_Obj *objv[7], *result, **typeObj, *data = NULL, *type,
              *pressedkeys = NULL;
      int i, type_index, status, index, typeObjc;
      static char *DropTypes[] = {
        "CF_UNICODETEXT", "CF_TEXT", "CF_HDROP",
        "FileGroupDescriptorW", "FileGroupDescriptor",
        (char *) NULL
      };
      enum droptypes {
        TYPE_CF_UNICODETEXT, TYPE_CF_TEXT, TYPE_CF_HDROP,
        TYPE_FILEGROUPDESCRIPTORW, TYPE_FILEGROUPDESCRIPTOR
      };
      static char *DropActions[] = {
        "copy", "move", "link", "ask",  "private", "refuse_drop",
        "default",
        (char *) NULL
      };
      enum dropactions {
        ActionCopy, ActionMove, ActionLink, ActionAsk, ActionPrivate,
        refuse_drop, ActionDefault
      };
      *pdwEffect = DROPEFFECT_NONE;
      // Get the drop format list.
      objv[0] = Tcl_NewStringObj("tkdnd::olednd::_GetDropTypes", -1);
      objv[1] = Tcl_NewStringObj(Tk_PathName(tkwin), -1);
      TkDND_Status_Eval(2); if (status != TCL_OK) return S_OK;
      result = Tcl_GetObjResult(interp); Tcl_IncrRefCount(result);
      status = Tcl_ListObjGetElements(interp, result, &typeObjc, &typeObj);
      if (status != TCL_OK) {Tcl_DecrRefCount(result); return S_OK;}
      // Try to get the data.
      for (type_index = 0; type_index < typeObjc; ++type_index) {
        status = Tcl_GetIndexFromObj(interp, typeObj[type_index],
                             (const char **)DropTypes, "droptypes", 0, &index);
        if (status == TCL_OK) {
          switch ((enum droptypes) index) {
            case TYPE_CF_UNICODETEXT:
              data = GetData_CF_UNICODETEXT(pDataObject); break;
            case TYPE_CF_TEXT:
              data = GetData_CF_TEXT(pDataObject); break;
            case TYPE_CF_HDROP:
              data = GetData_CF_HDROP(pDataObject); break;
            case TYPE_FILEGROUPDESCRIPTORW:
              // Get a directory where we can store files...
              objv[0]=Tcl_NewStringObj("tkdnd::GetDropFileTempDirectory", -1);
              TkDND_Status_Eval(1);
              if (status == TCL_OK) {
                strcpy(szTempStr, Tcl_GetStringResult(interp));
                data = GetData_FileGroupDescriptorW(pDataObject);
              }
              break;
            case TYPE_FILEGROUPDESCRIPTOR:
              // Get a directory where we can store files...
              objv[0] = Tcl_NewStringObj("tkdnd::GetDropFileTempDirectory", -1);
              TkDND_Status_Eval(1);
              if (status == TCL_OK) {
                strcpy(szTempStr, Tcl_GetStringResult(interp));
                data = GetData_FileGroupDescriptor(pDataObject);
              }
              break;
          }
        }
        if (data != NULL) {
          type = typeObj[type_index]; Tcl_IncrRefCount(type);
          break; // We have got the data!
        }
      }

      if (data == NULL) {
        // We failed to get the data.
        type = typeObj[0]; Tcl_IncrRefCount(type);
        data = GetData_Bytearray(pDataObject, type);
      }
      Tcl_DecrRefCount(result);

      // Get the state of the keyboard modifier keys.
      // MK_CONTROL, MK_SHIFT, MK_ALT, MK_RBUTTON, MK_LBUTTON
      pressedkeys = Tcl_NewListObj(0, NULL);
      if (grfKeyState & MK_CONTROL)
        Tcl_ListObjAppendElement(NULL,pressedkeys,Tcl_NewStringObj("ctrl", -1));
      if (grfKeyState & MK_SHIFT)
        Tcl_ListObjAppendElement(NULL,pressedkeys,Tcl_NewStringObj("shift",-1));
      if (grfKeyState & MK_ALT)
        Tcl_ListObjAppendElement(NULL,pressedkeys,Tcl_NewStringObj("alt", -1));
      if (grfKeyState & MK_RBUTTON)
        Tcl_ListObjAppendElement(NULL,pressedkeys,Tcl_NewStringObj("3", -1));
      if (grfKeyState & MK_MBUTTON)
        Tcl_ListObjAppendElement(NULL,pressedkeys,Tcl_NewStringObj("2", -1));
      if (grfKeyState & MK_LBUTTON)
        Tcl_ListObjAppendElement(NULL,pressedkeys,Tcl_NewStringObj("1", -1));

      // We are ready to pass the info to the Tcl level, and get the desired
      // action.
      objv[0] = Tcl_NewStringObj("tkdnd::olednd::_HandleDrop", -1);
      objv[1] = Tcl_NewStringObj(Tk_PathName(tkwin), -1);
      objv[2] = pressedkeys;
      objv[3] = Tcl_NewLongObj(pt.x);
      objv[4] = Tcl_NewLongObj(pt.y);
      objv[5] = type;
      objv[6] = data;
      TkDND_Status_Eval(7);
      Tcl_DecrRefCount(type);
      *pdwEffect = DROPEFFECT_NONE;
      if (status == TCL_OK) {
        /* Get the returned action... */
        result = Tcl_GetObjResult(interp); Tcl_IncrRefCount(result);
        status = Tcl_GetIndexFromObj(interp, result, (const char **)DropActions,
                                     "dropactions", 0, &index);
        Tcl_DecrRefCount(result);
        if (status != TCL_OK) index = refuse_drop;
      }
      switch ((enum dropactions) index) {
        case ActionCopy:    *pdwEffect = DROPEFFECT_COPY; break;
        case ActionMove:    *pdwEffect = DROPEFFECT_MOVE; break;
        case ActionLink:    *pdwEffect = DROPEFFECT_LINK; break;
        case ActionAsk:     *pdwEffect = DROPEFFECT_NONE; break;
        case ActionPrivate: *pdwEffect = DROPEFFECT_NONE; break;
        case ActionDefault: *pdwEffect = DROPEFFECT_COPY; break;
        case refuse_drop:   *pdwEffect = DROPEFFECT_NONE; /* Refuse drop. */
      }

      return S_OK;
    }; /* Drop */

    /* TkDND additional interface methods */
private:

    Tcl_Obj *GetData_Bytearray(IDataObject *pDataObject, Tcl_Obj *formatObj) {
      STGMEDIUM StgMed;
      FORMATETC fmte = { 0, (DVTARGETDEVICE FAR *)NULL,
                         DVASPECT_CONTENT, -1, TYMED_HGLOBAL };
      Tcl_Obj *result;
      unsigned char *bytes;
      fmte.cfFormat = RegisterClipboardFormat(Tcl_GetString(formatObj));
      if (pDataObject->QueryGetData(&fmte) != S_OK ||
          pDataObject->GetData(&fmte, &StgMed) != S_OK ) {
        Tcl_NewStringObj("unsupported type", -1);
      }
      bytes = (unsigned char *) GlobalLock(StgMed.hGlobal);
      result = Tcl_NewByteArrayObj(bytes, GlobalSize(StgMed.hGlobal));
      GlobalUnlock(StgMed.hGlobal);
      ReleaseStgMedium(&StgMed);
      return result;
    }; /* GetData_Bytearray */

    Tcl_Obj *GetData_CF_UNICODETEXT(IDataObject *pDataObject) {
      STGMEDIUM StgMed;
      FORMATETC fmte = { CF_UNICODETEXT, (DVTARGETDEVICE FAR *)NULL,
                         DVASPECT_CONTENT, -1, TYMED_HGLOBAL };

      if (pDataObject->QueryGetData(&fmte) == S_OK) {
        if (pDataObject->GetData(&fmte, &StgMed) == S_OK) {
          Tcl_DString ds;
          char *data, *destPtr;
          data = (char *) GlobalLock(StgMed.hGlobal);
          Tcl_DStringInit(&ds);
          Tcl_UniCharToUtfDString((Tcl_UniChar *) data,
              Tcl_UniCharLen((Tcl_UniChar *) data), &ds);
          GlobalUnlock(StgMed.hGlobal);
          ReleaseStgMedium(&StgMed);
          /*  Translate CR/LF to LF.  */
          data = destPtr = Tcl_DStringValue(&ds);
          while (*data) {
              if (data[0] == '\r' && data[1] == '\n') {
                  data++;
              } else {
                  *destPtr++ = *data++;
              }
          }
          *destPtr = '\0';
          Tcl_Obj *result = Tcl_NewStringObj(Tcl_DStringValue(&ds), -1);
          Tcl_DStringFree(&ds);
          return result;
        }
      }
      return NULL;
    }; /* GetData_CF_UNICODETEXT */

    Tcl_Obj *GetData_CF_TEXT(IDataObject *pDataObject) {
      STGMEDIUM StgMed;
      FORMATETC fmte = { CF_TEXT, (DVTARGETDEVICE FAR *)NULL,
                         DVASPECT_CONTENT, -1, TYMED_HGLOBAL };
      FORMATETC fmte_locale = { CF_LOCALE, (DVTARGETDEVICE FAR *)NULL,
                         DVASPECT_CONTENT, -1, TYMED_HGLOBAL };

      if (pDataObject->QueryGetData(&fmte) == S_OK) {
        // Determine the encoding to use to convert this text.
        Tcl_Encoding encoding = NULL;
        char *data, *destPtr;
        if (pDataObject->QueryGetData(&fmte_locale) == S_OK) {
          if (pDataObject->GetData(&fmte_locale, &StgMed) == S_OK) {
            Tcl_DString ds;
            int locale;
            Tcl_DStringInit(&ds);
            Tcl_DStringAppend(&ds, "cp######", -1);
            data = (char *) GlobalLock(StgMed.hGlobal);
            /*
             * Even though the documentation claims that GetLocaleInfo expects
             * an LCID, on Windows 9x it really seems to expect a LanguageID.
             */
            locale = LANGIDFROMLCID(*((int*) data));
            GetLocaleInfo(locale, LOCALE_IDEFAULTANSICODEPAGE,
                    Tcl_DStringValue(&ds)+2, Tcl_DStringLength(&ds)-2);
            GlobalUnlock(StgMed.hGlobal);
            encoding = Tcl_GetEncoding(NULL, Tcl_DStringValue(&ds));
            Tcl_DStringFree(&ds);
          }
        }
        if (pDataObject->GetData(&fmte, &StgMed) == S_OK) {
          Tcl_DString ds;

          data = (char *) GlobalLock(StgMed.hGlobal);
          Tcl_DStringInit(&ds);
          Tcl_ExternalToUtfDString(encoding, data, -1, &ds);
          GlobalUnlock(StgMed.hGlobal);
          ReleaseStgMedium(&StgMed);
          if (encoding) Tcl_FreeEncoding(encoding);

          /*  Translate CR/LF to LF.  */
          data = destPtr = Tcl_DStringValue(&ds);
          while (*data) {
              if (data[0] == '\r' && data[1] == '\n') {
                  data++;
              } else {
                  *destPtr++ = *data++;
              }
          }
          *destPtr = '\0';
          Tcl_Obj *result = Tcl_NewStringObj(Tcl_DStringValue(&ds), -1);
          Tcl_DStringFree(&ds);
          return result;
        }
      }
      return NULL;
    }; /* GetData_CF_TEXT */

    Tcl_Obj *GetData_CF_HDROP(IDataObject *pDataObject) {
      STGMEDIUM StgMed;
      FORMATETC fmte = { CF_HDROP, (DVTARGETDEVICE FAR *)NULL,
                         DVASPECT_CONTENT, -1, TYMED_HGLOBAL };

      if (pDataObject->QueryGetData(&fmte) == S_OK) {
        if (pDataObject->GetData(&fmte, &StgMed) == S_OK) {
          HDROP hdrop = (HDROP) GlobalLock(StgMed.hGlobal);
          UINT cFiles = ::DragQueryFile(hdrop, (UINT)-1, NULL, 0);
          char szFile[MAX_PATH], *p;
          Tcl_Obj *result = Tcl_NewListObj(0, NULL);
          for( UINT count = 0; count < cFiles; count++ ) {
            ::DragQueryFile(hdrop, count, szFile, sizeof(szFile));
            /* Convert to forward slashes for easier access in scripts... */
            for (p=szFile; *p!='\0'; p=(char *) CharNext(p)) {
              if (*p == '\\') *p = '/';
            }
            Tcl_ListObjAppendElement(NULL, result, Tcl_NewStringObj(szFile,-1));
          }
          GlobalUnlock(StgMed.hGlobal);
          ReleaseStgMedium(&StgMed);
          //if (StgMed.pUnkForRelease) { StgMed.pUnkForRelease->Release(); }
          //else { ::GlobalFree(StgMed.hGlobal); }
          return result;
        }
      }
      return NULL;
    }; /* GetData_CF_HDROP */

#define BLOCK_SIZE 1024
    HRESULT StreamToFile(IStream *stream, char *file_name) {
      byte buffer[BLOCK_SIZE];
      unsigned long bytes_read = 0;
      int bytes_written = 0;
      int new_file;
      HRESULT hr = S_OK;

      new_file = sopen(file_name, O_RDWR | O_BINARY | O_CREAT,
                                  SH_DENYNO, S_IREAD | S_IWRITE);
      if (new_file != -1) {
        do {
          hr = stream->Read(buffer, BLOCK_SIZE, &bytes_read);
          if (bytes_read) bytes_written = write(new_file, buffer, bytes_read);
        } while (S_OK == hr && bytes_read == BLOCK_SIZE);
        close(new_file);
        if (bytes_written == 0) unlink(file_name);
      } else {
        unsigned long error;
        if ((error = GetLastError()) == 0L) error = _doserrno;
        hr = HRESULT_FROM_WIN32(errno);
      }
      return hr;
    }; /* StreamToFile */

    Tcl_Obj *GetData_FileGroupDescriptor(IDataObject *pDataObject) {
      STGMEDIUM StgMed;
      FORMATETC fmte_locale    = { CF_LOCALE, (DVTARGETDEVICE FAR *) NULL,
                                   DVASPECT_CONTENT, -1, TYMED_HGLOBAL };
      FORMATETC descriptor_fmt = { 0, (DVTARGETDEVICE FAR *) NULL,
                                   DVASPECT_CONTENT, -1, TYMED_HGLOBAL };
      FORMATETC contents_fmt   = { 0, (DVTARGETDEVICE FAR *) NULL,
                                   DVASPECT_CONTENT, -1, TYMED_ISTREAM };
      HRESULT hr = S_OK;
      FILEGROUPDESCRIPTOR *file_group_descriptor;
      FILEDESCRIPTOR file_descriptor;
      Tcl_Encoding encoding = NULL;

      descriptor_fmt.cfFormat = RegisterClipboardFormat(CFSTR_FILEDESCRIPTOR);
      contents_fmt.cfFormat   = RegisterClipboardFormat(CFSTR_FILECONTENTS);
      if (pDataObject->QueryGetData(&descriptor_fmt) != S_OK) return NULL;
      if (pDataObject->QueryGetData(&contents_fmt) != S_OK) return NULL;
      // Get the descriptor information
      STGMEDIUM storage = {0,0,0};
      hr = pDataObject->GetData(&descriptor_fmt, &storage);
      if (hr != S_OK) return NULL;
      file_group_descriptor = (FILEGROUPDESCRIPTOR *)
                              GlobalLock(storage.hGlobal);
      // Determine the encoding to use to convert this text.
      if (pDataObject->QueryGetData(&fmte_locale) == S_OK) {
        if (pDataObject->GetData(&fmte_locale, &StgMed) == S_OK) {
          Tcl_DString ds;
          int locale;
          Tcl_DStringInit(&ds);
          Tcl_DStringAppend(&ds, "cp######", -1);
          char *data = (char *) GlobalLock(StgMed.hGlobal);
          /*
           * Even though the documentation claims that GetLocaleInfo expects
           * an LCID, on Windows 9x it really seems to expect a LanguageID.
           */
          locale = LANGIDFROMLCID(*((int*) data));
          GetLocaleInfo(locale, LOCALE_IDEFAULTANSICODEPAGE,
                  Tcl_DStringValue(&ds)+2, Tcl_DStringLength(&ds)-2);
          GlobalUnlock(StgMed.hGlobal);
          encoding = Tcl_GetEncoding(NULL, Tcl_DStringValue(&ds));
          Tcl_DStringFree(&ds);
        }
      }
      Tcl_Obj *result = Tcl_NewListObj(0, NULL);
      // For each file, get the name and copy the stream to a file
      for (unsigned int file_index = 0;
           file_index < file_group_descriptor->cItems; file_index++) {
        STGMEDIUM content_storage = {TYMED_ISTREAM,0,0};
        file_descriptor = file_group_descriptor->fgd[file_index];
        contents_fmt.lindex = file_index;
        if (pDataObject->GetData(&contents_fmt, &content_storage) == S_OK) {
          // Dump stream into a file.
          char file_name[MAX_PATH+1];
          GlobalLock(content_storage.pstm);
          strcpy(file_name, (char *) szTempStr);
          strcat(file_name, "\\");
          strcat(file_name, file_descriptor.cFileName);
          if (StreamToFile(content_storage.pstm, file_name) == S_OK) {
            Tcl_DString ds;
            Tcl_DStringInit(&ds);
            Tcl_ExternalToUtfDString(encoding, file_name, -1, &ds);
            Tcl_ListObjAppendElement(NULL, result,
                       Tcl_NewStringObj(Tcl_DStringValue(&ds), -1));
            Tcl_DStringFree(&ds);
          }
          GlobalUnlock(content_storage.pstm);
        }
        ReleaseStgMedium(&content_storage);
      }
      GlobalUnlock(storage.hGlobal);
      ReleaseStgMedium(&storage);
      if (encoding) Tcl_FreeEncoding(encoding);
      return result;
    }; /* GetData_FileGroupDescriptor */

    HRESULT StreamToFileW(IStream *stream, Tcl_UniChar *file_name) {
      byte buffer[BLOCK_SIZE];
      unsigned long bytes_read = 0;
      int bytes_written = 0;
      int new_file;
      HRESULT hr = S_OK;

      new_file = _wsopen((wchar_t const *)file_name, O_RDWR | O_BINARY | O_CREAT,
                                  SH_DENYNO, S_IREAD | S_IWRITE);
      if (new_file != -1) {
        do {
          hr = stream->Read(buffer, BLOCK_SIZE, &bytes_read);
          if (bytes_read) bytes_written = write(new_file, buffer, bytes_read);
        } while (S_OK == hr && bytes_read == BLOCK_SIZE);
        close(new_file);
        if (bytes_written == 0) _wunlink((wchar_t const *)file_name);
        return S_OK;
      } else {
        unsigned long error;
        if ((error = GetLastError()) == 0L) error = _doserrno;
        hr = HRESULT_FROM_WIN32(errno);
      }
      return hr;
    }; /* StreamToFileW */

    Tcl_Obj *GetData_FileGroupDescriptorW(IDataObject *pDataObject) {
      FORMATETC descriptor_fmt = { 0, (DVTARGETDEVICE FAR *) NULL,
                                   DVASPECT_CONTENT, -1, TYMED_HGLOBAL };
      FORMATETC contents_fmt   = { 0, (DVTARGETDEVICE FAR *) NULL,
                                   DVASPECT_CONTENT, -1, TYMED_ISTREAM };
      HRESULT hr = S_OK;
      FILEGROUPDESCRIPTORW *file_group_descriptor;
      FILEDESCRIPTORW file_descriptor;
      Tcl_Obj *item;

      descriptor_fmt.cfFormat = RegisterClipboardFormat(CFSTR_FILEDESCRIPTORW);
      contents_fmt.cfFormat   = RegisterClipboardFormat(CFSTR_FILECONTENTS);
      if (pDataObject->QueryGetData(&descriptor_fmt) != S_OK) return NULL;
      if (pDataObject->QueryGetData(&contents_fmt) != S_OK) return NULL;
      // Get the descriptor information
      STGMEDIUM storage = {0,0,0};
      hr = pDataObject->GetData(&descriptor_fmt, &storage);
      if (hr != S_OK) return NULL;
      file_group_descriptor = (FILEGROUPDESCRIPTORW *)
                              GlobalLock(storage.hGlobal);

      Tcl_Obj *result = Tcl_NewListObj(0, NULL);
      // For each file, get the name and copy the stream to a file
      for (unsigned int file_index = 0;
           file_index < file_group_descriptor->cItems; file_index++) {
        STGMEDIUM content_storage = {TYMED_ISTREAM,0,0};
        file_descriptor = file_group_descriptor->fgd[file_index];
        contents_fmt.lindex = file_index;
        if (pDataObject->GetData(&contents_fmt, &content_storage) == S_OK) {
          // Dump stream into a file.
          item = Tcl_NewStringObj(szTempStr, -1);
          Tcl_AppendToObj(item, "\\", 1);
          Tcl_GetUnicode(item);
          Tcl_AppendUnicodeToObj(item, (Tcl_UniChar *)file_descriptor.cFileName, -1);
          GlobalLock(content_storage.pstm);
          if (StreamToFileW(content_storage.pstm, Tcl_GetUnicode(item))==S_OK) {
            Tcl_ListObjAppendElement(NULL, result, item);
#if 0
          } else {
            LPVOID lpMsgBuf;
            if (!FormatMessage( FORMAT_MESSAGE_ALLOCATE_BUFFER |
                FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
                NULL, GetLastError(),
                MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), // Default language
                (LPTSTR) &lpMsgBuf, 0, NULL )) {
               // Handle the error.
            }
            // Display the string.
            MessageBox( NULL, (LPCTSTR)lpMsgBuf, "Error",
                        MB_OK | MB_ICONINFORMATION );
            // Free the buffer.
            LocalFree( lpMsgBuf );
#endif
          }
          GlobalUnlock(content_storage.pstm);
        }
        ReleaseStgMedium(&content_storage);
      }
      GlobalUnlock(storage.hGlobal);
      ReleaseStgMedium(&storage);
      return result;
    }; /* GetData_FileGroupDescriptorW */

}; /* TkDND_DropTarget */

/*****************************************************************************
 * Drop Source Related Class.
 ****************************************************************************/
class TkDND_DropSource : public IDropSource {
public:
    // IUnknown members
    HRESULT __stdcall QueryInterface(REFIID iid, void ** ppvObject) {
      // check to see what interface has been requested
      if (iid == IID_IDropSource || iid == IID_IUnknown) {
          AddRef();
          *ppvObject = this;
          return S_OK;
      } else {
          *ppvObject = 0;
          return E_NOINTERFACE;
      }
    }; /* QueryInterface */

    ULONG   __stdcall AddRef(void) {
      // increment object reference count
      return InterlockedIncrement(&m_lRefCount);
    }; /* AddRef */

    ULONG   __stdcall Release(void) {
      // decrement object reference count
      LONG count = InterlockedDecrement(&m_lRefCount);
      if (count == 0) { delete this; return 0; }
      else { return count; };
    }; /* Release */

    // IDropSource members

    //  Called by OLE whenever Escape/Control/Shift/Mouse buttons have changed
    HRESULT __stdcall QueryContinueDrag(BOOL fEscapePressed, DWORD grfKeyState){
      // if the <Escape> key has been pressed since the last call,
      // cancel the drop
      if(fEscapePressed == TRUE) return DRAGDROP_S_CANCEL;

      // if the <LeftMouse> button has been released, then do the drop!
      if((grfKeyState & MK_LBUTTON) == 0) return DRAGDROP_S_DROP;

      // continue with the drag-drop
      return S_OK;
    }; /* QueryContinueDrag */

    // Return either S_OK, or DRAGDROP_S_USEDEFAULTCURSORS to instruct
    // OLE to use the default mouse cursor images...
    HRESULT __stdcall GiveFeedback(DWORD dwEffect) {
      return DRAGDROP_S_USEDEFAULTCURSORS;
    }; /* GiveFeedback */

    // Constructor / Destructor
    TkDND_DropSource() {
      m_lRefCount = 1;
    }; /* TkDND_DropSource */

    ~TkDND_DropSource() {};

private:
    LONG   m_lRefCount;
}; /* TkDND_DropSource */


#endif _OLE_DND_H
