Re: Problem with drag&drop into a control

From:
"James Duy Trinh \(VietDoor\)" <vietdoor@gmail.com>
Newsgroups:
microsoft.public.vc.mfc
Date:
Fri, 28 Nov 2008 10:52:54 +0700
Message-ID:
<#UxXYzQUJHA.1172@TK2MSFTNGP03.phx.gbl>
i use an Old inherit from COleDataSource, and register format
UINT g_uCustomClipbrdFormat = RegisterClipboardFormat(CFSTR_FILECONTENTS);

// --------------------------------------------------
// my code starts here
//COleDataSource datasrc;
 //for dragging image
 COleDataSourceEx datasrc;

 HGLOBAL hgDrop;
 DROPFILES* pDrop;
 CStringList lsDraggedFiles;
 POSITION pos;
 int nSelItem;
 CString sFile;
 UINT uBuffSize = 0;
 TCHAR* pszBuff;
 FORMATETC etc = { CF_HDROP, NULL, DVASPECT_CONTENT, -1, TYMED_HGLOBAL };
 //FORMATETC etc = { g_uCustomClipbrdFormat, NULL, DVASPECT_CONTENT, -1,
TYMED_HGLOBAL };

 *pResult = 0; // return value ignored

 // For every selected item in the list, put the filename into
lsDraggedFiles.
 pos = this->GetFirstSelectedItemPosition();

 while(NULL != pos)
 {
  nSelItem = this->GetNextSelectedItem(pos);
  sFile = this->GetFileNameFromIdx(nSelItem);

  lsDraggedFiles.AddTail(sFile);

  // Calculate the # of chars required to hold this string.
  uBuffSize += lstrlen(sFile) + 1;
 }

 // Add 1 extra for the final null char, and the size of the DROPFILES
struct.
 uBuffSize = sizeof(DROPFILES) + sizeof(TCHAR) * (uBuffSize + 1);

 // Allocate memory from the heap for the DROPFILES struct.
 hgDrop = GlobalAlloc(GHND | GMEM_SHARE, uBuffSize);
 //hgDrop = GlobalAlloc(GMEM_MOVEABLE|GMEM_DDESHARE|GMEM_ZEROINIT,
uBuffSize);

 if(NULL == hgDrop)
  return;

 pDrop = (DROPFILES*) GlobalLock(hgDrop);

 if(NULL == pDrop)
 {
  GlobalFree(hgDrop);
  return;
 }

 // Fill in the DROPFILES struct.
 pDrop->pFiles = sizeof(DROPFILES);

#ifdef _UNICODE
 // If we're compiling for Unicode, set the Unicode flag in the struct to
 // indicate it contains Unicode strings.
 pDrop->fWide = TRUE;
#endif

 // Copy all the filenames into memory after the end of the DROPFILES
struct.
 pos = lsDraggedFiles.GetHeadPosition();
 pszBuff = (TCHAR*) (LPBYTE(pDrop) + sizeof(DROPFILES));

 while(NULL != pos)
 {
  lstrcpy(pszBuff, (LPCTSTR) lsDraggedFiles.GetNext(pos));
  pszBuff = 1 + _tcschr(pszBuff, '\0');
 }

 GlobalUnlock(hgDrop);

 // Put the data in the data source.
 //datasrc.CacheGlobalData(CF_HDROP, hgDrop, &etc);
 datasrc.CacheGlobalData(g_uCustomClipbrdFormat, hgDrop, &etc);

 // Add in our own custom data, so we know that the drag originated from our
 // window. CMyDropTarget::DragEnter() checks for this custom format, and
 // doesn't allow the drop if it's present. This is how we prevent the user
 // from dragging and then dropping in our own window.
 // The data will just be a dummy bool.
 HGLOBAL hgBool;

 hgBool = GlobalAlloc(GHND | GMEM_SHARE, sizeof(bool));

 if(NULL == hgBool)
 {
  GlobalFree(hgDrop);
  return;
 }

 // Put the data in the data source.
 etc.cfFormat = g_uCustomClipbrdFormat;
 datasrc.CacheGlobalData(g_uCustomClipbrdFormat, hgBool, &etc);

 //PRAPARE IMAGE FOR DRAGGING
 if (m_UseDragHelper) {
  m_pDragHelper->InitializeFromWindow(this->m_hWnd,
&pNMLV->ptAction,(IDataObject*)datasrc.GetInterface(&IID_IDataObject));
  this->SetPivotItem(&pNMLV->ptAction);
 }

 // Start the drag 'n' drop!
 DROPEFFECT dwEffect = datasrc.DoDragDrop(DROPEFFECT_COPY | DROPEFFECT_MOVE
| DROPEFFECT_LINK);

"David Ching" <dc@remove-this.dcsoft.com> wrote in message
news:93037955-F988-4388-BA72-9A6DAAD23C35@microsoft.com...

"James Duy Trinh (VietDoor)" <vietdoor@gmail.com> wrote in message
news:%237HMVMFUJHA.5024@TK2MSFTNGP03.phx.gbl...

Hi all,

i have a problem with drag&drop into Skype's control. I implemented a
function to drag a file from my app and then drop it into Skype's chat
window. But some controls accepted and others can't.
How to allow all controls can understand.


Perhaps something in your implementation of IDropS0urce or IDataObject is
wrong? Can you find tutorials that show how to implement these?

-- David

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