I'm doing a small example, drag and drop probably described as follows:

A Form has A Label, the Label of the Caption to A local file (file A) the full path, drag the Label to the resource manager E dish to loosen, the file will be copied to A disc E, I realized the IDataObject and IDropSource interface, don't know if implementation problems, always display ban drop when drag and drop ICONS,

complete code can be downloaded here:
http://pan.baidu.com/s/1eQcUbPS
The code is as follows:
MyDataObject. H

 
#include  
# include "IDragDemo. H" 

The class MyDataObject: public IDataObject 
{
Public: 
//IUnknown implementation 
ULONG __stdcall AddRef (); 
ULONG __stdcall Release (); 
STDMETHODIMP QueryInterface (REFIID riid, void * * ppvObject); 

//IDataObject members 
STDMETHODIMP GetData (FORMATETC * pformatetcIn, STGMEDIUM * pmedium); 
STDMETHODIMP GetDataHere (FORMATETC * pformatetc, STGMEDIUM * pmedium); 
STDMETHODIMP QueryGetData (FORMATETC * pformatetc); 
STDMETHODIMP GetCanonicalFormatEtc (FORMATETC * pformatectIn, FORMATETC * pformatetcOut); 
STDMETHODIMP SetData (FORMATETC * pformatetc, STGMEDIUM * pmedium, BOOL fRelease); 
STDMETHODIMP EnumFormatEtc (DWORD dwDirection IEnumFORMATETC * * ppenumFormatEtc); 
STDMETHODIMP DAdvise (FORMATETC * pformatetc, dwords advf IAdviseSink * pAdvSink, dwords * pdwConnection); 
STDMETHODIMP DUnadvise (DWORD dwConnection); 
* * ppenumAdvise STDMETHODIMP EnumDAdvise (IEnumSTATDATA); 
Public: 
MyDataObject vFileName (char *); 
~ MyDataObject (); 
Private: 
LONG refcount; 

//custom formatting 
FORMATETC m_AcceptFormat; 
STGMEDIUM m_StorageMedium; 

HGLOBAL DupGlobalMem (HGLOBAL hMem); 
}; 

MyDataObject. CPP

 
# include "MyDataObject. H" 
# include "MyDropSource. H" 
#include  

//Constructors 
MyDataObject: : MyDataObject vFileName (char *) : refcount (1) 
{
//set the custom accept the format for 
M_AcceptFormat. CfFormat=CF_HDROP; 
M_AcceptFormat. DwAspect=DVASPECT_CONTENT; 
M_AcceptFormat. Tymed=TYMED_HGLOBAL; 

//create a DROPFILES instance 
DROPFILES tDropFiles; 
TDropFiles. As fNC=false; 
TDropFiles. FWide=true; 
TDropFiles. PFiles=sizeof (DROPFILES); 
TDropFiles. Pt. X=0; 
TDropFiles. Pt. Y=0; 

//produce custom storage media 
M_StorageMedium. Tymed=TYMED_HGLOBAL; 
M_StorageMedium. PUnkForRelease=NULL; 
M_StorageMedium. HGlobal=& amp; TDropFiles; 

//set the file name format 
HGLOBAL hGblFiles; 
LPSTR lpData. 
HGblFiles=GlobalAlloc (GMEM_ZEROINIT | GMEM_MOVEABLE | GMEM_DDESHARE, sizeof (DROPFILES) + strlen (vFileName) + 2); 

//for hGblFiles allocates memory and initialization 
Char tFileName [256]. 
LpData=https://bbs.csdn.net/topics/(LPSTR) GlobalLock (hGblFiles); 
Memcpy (lpData, & amp; TDropFiles, sizeof (DROPFILES)); 
Strcpy (lpData + sizeof (DROPFILES), vFileName); 
GlobalUnlock (hGblFiles); 

//call SetData 
SetData (& amp; M_AcceptFormat, & amp; M_StorageMedium, true); 

//called DoDragDrop 
MyDropSource tDropSource; 
DWORD dwEffect; 

DoDragDrop (this, & amp; TDropSource DROPEFFECT_COPY, & amp; DwEffect); 

Fprintf (stdout, Initiate a data object. \n"); 
} 

//Destructors 
MyDataObject: : ~ MyDataObject () 
{
Fprintf (stdout, Destruct a data object. \n"); 
} 

//IUnkown implementation 
ULONG __stdcall MyDataObject: : AddRef () 
{
Return InterlockedIncrement (& amp; Refcount); 
} 

ULONG __stdcall MyDataObject: : Release () 
{
ULONG nRefCount=InterlockedDecrement (& amp; Refcount); 

If (nRefCount==0) 
Delete this. 

Return nRefCount; 
} 

STDMETHODIMP MyDataObject: : QueryInterface (REFIID riid, void * * ppvObject) {
if (! PpvObject) return E_POINTER; 

If (riid==IID_IUnknown) {
* ppvObject=static_cast & lt; IUnknown * & gt; (this); 
AddRef (); 
Return S_OK. 
{} else if (riid==IID_IDropSource) 
* ppvObject=static_cast & lt; IDataObject * & gt; (this); 
AddRef (); 
Return S_OK. 
} else {
* ppvObject=NULL; 
Return E_NOINTERFACE; 
} 
} 

//Data Object implement 
//present specified pformatetcIn structure described in the data, and sending it to the pmedium 
STDMETHODIMP MyDataObject: : GetData (FORMATETC * pformatetcIn, STGMEDIUM * pmedium) 
{
If (pformatetcIn==NULL | | pmedium==NULL) return E_INVALIDARG; 

//to empty medium 
Memset (pmedium, 0, sizeof (STGMEDIUM)); 

//type better if accepted 
//if ((m_AcceptFormat tymed & amp; PformatetcIn - & gt; Tymed) & amp; & 
//(m_AcceptFormat dwAspect==pformatetcIn - & gt; DwAspect) & amp; & 
//(m_AcceptFormat cfFormat==pformatetcIn - & gt; CfFormat)) {

//to qualified data filling into pmedium 
Pmedium - & gt; HGlobal=DupGlobalMem (m_StorageMedium. HGlobal); 

//retrieves the hr=CopyStgMedium (pmedium, & amp; M_StorageMedium); 
//
//if (S_OK!=hr) 
//return DV_E_FORMATETC; 
//
//if (pmedium - & gt; Tymed=={TYMED_HGLOBAL) 
nullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnull