Resending:

Hi,

I am writing a .Net wrapper for the MS object picker, but I am
running into a marshalling problem.

I am having trouble retrieving data returned after selecting users and
clicking OK. When I call the dataObj.GetData (...) it returns a handle
inside STGMEDIUM that is invalid. The GetLastWin32Error returns an
Error Code 6. (ERROR_INVALID_HANDLE)

Please see code below.

Ill appreciate any input on this issue.

Thanks in advance,
Abhinav

/**********************************************
This is code to extract the data
***********************************************/
       private string ProcessSelectedObjects (IDataObject dataObj)
       {
           STGMEDIUM stg = new STGMEDIUM ();
           stg.tymed = (uint) TYMED.TYMED_HGLOBAL;
           stg.pUnkForRelease = null;
           stg.hGlobal = IntPtr.Zero;

           FORMATETC fetc = new FORMATETC ();
           fetc.cfFormat = PInvoke.RegisterClipboardFormat
(CLIPBOARD_FORMAT.CFSTR_DSOP_DS_SELECTION_LIST);
           fetc.ptd = 0;
           fetc.dwAspect = (uint) DVASPECT.DVASPECT_CONTENT;
           fetc.lindex = -1;
           fetc.tymed = (uint) TYMED.TYMED_HGLOBAL;

           int hr = dataObj.GetData (ref fetc, ref stg);

           if (hr != HRESULT.S_OK)
           {
               //error
           }

           int error = 0;
           
           IntPtr ptr = PInvoke.GlobalLock(stg.hGlobal);

           if (ptr == IntPtr.Zero)
           {
               error = Marshal.GetLastWin32Error ();
           }

           PInvoke.GlobalUnlock(ptr);
       }

/*********************************
These are the structures
**********************************/
  /* Interfaces */
   [
   ComImport,
   CLSCompliant(false),
   Guid("0000010e-0000-0000-C000-000000000046"),
   InterfaceType(ComInterfaceType.InterfaceIsIUnknown)
   ]
   public interface IDataObject
   {
       [PreserveSig ()]
       int GetData(ref FORMATETC pFormatEtc, ref STGMEDIUM b);

       void GetDataHere(ref FORMATETC pFormatEtc, ref STGMEDIUM b);

       [PreserveSig()]
       int QueryGetData(IntPtr a);

       [PreserveSig()]
       int GetCanonicalFormatEtc(IntPtr a, IntPtr b);

       [PreserveSig()]
       int SetData(IntPtr a, IntPtr b, int c);

       [PreserveSig()]
       int EnumFormatEtc(uint a, IntPtr b);

       [PreserveSig()]
       int DAdvise(IntPtr a, uint b, IntPtr c, ref uint d);

       [PreserveSig()]
       int DUnadvise(uint a);

       [PreserveSig()]
       int EnumDAdvise(IntPtr a);
   }

   [
   CLSCompliant(false),
   StructLayout(LayoutKind.Sequential)
   ]
   public struct FORMATETC
   {
       public int cfFormat;
       public int ptd;
       public uint dwAspect;
       public int lindex;
       public uint tymed;
   }

   [
   CLSCompliant(false),
   StructLayout(LayoutKind.Sequential)
   ]
   public struct STGMEDIUM
   {
       public uint tymed;
       public IntPtr hGlobal;
       public Object pUnkForRelease;
   }

/********************************************
Call to INvokeDialog
********************************************/
       public override string InvokeDialog (IntPtr handle)
       {
           IDsObjectPicker idop = null;
           idop = Initialize ();

           IDataObject dataObj = null;
           idop.InvokeDialog(handle, out dataObj);

           //have to process dataObj and return SID string
           return ProcessSelectedObjects (dataObj);
       }