답변감사합니다. 한가지더 질문입니다.
DragOver인 상태에서의 아이콘 변경이 가능한지요.
가능하다면 방법을 알고 싶습니다.


유영인 [Chris] 님이 쓰신 글 :
: 아래 OLE Drag&Drop 설명과 예제입니다..
:
:
:
: The WM_DROPFILES message is specifically meant for the transfer of files from
: Explorer to an application. Using the message is simple, but as you've
: discovered, it's limited. If you're looking to accept drops (i.e., data) from
: other applications, you'll need to use OLE drag-drop. Most applications use OLE
: for the transfer of data, so if you implement a "drop target" class, you will be
: able to accept this data and receive notification of the standard OLE drag-drop
: events (i.e., similar to OnDragEnter, OnDragOver, OnDrop, etc.). If you read
: the following reference, you can cut and paste the TDropTarget class from the
: CAQ and be up and running...
:
: http://bcbcaq.freeservers.com/project_DD.html
:
: In the article, I specifically target file transfers from Explorer. That is,
: the TDropTarget::HandleDrop(), DragEnter(), Drop(), and the TForm1::WMOleDrop()
: member functions specifically deal with the CF_HDROP format. If you're looking
: to accept text from browsers, you'll need to modify these functions to handle
: the CF_TEXT format. So, read the CAQ, try to modify it for the CF_TEXT format,
: then refer to the following example if you run into trouble...
:
: // in TDropTarget header...
:    // helper function -- modified for CF_TEXT
:    void __fastcall HandleDrop(const char* AText);
:
:
: // in TDropTarget source...
:
: // helper routine to notify Form of drop on target
: void __fastcall TDropTarget::HandleDrop(const char* AText)
: {
:     SNDMSG(FFormHandle, WM_OLEDROP, reinterpret_cast<WPARAM>(AText), 0);
: }
:
: // modified (for CF_TEXT) DragEnter
: STDMETHODIMP TDropTarget::DragEnter(LPDATAOBJECT pDataObj, DWORD grfKeyState,
:    POINTL pt, LPDWORD pdwEffect)
: {
:    FORMATETC fmtetc;
:    fmtetc.cfFormat = CF_TEXT;
:    fmtetc.ptd = NULL;
:    fmtetc.dwAspect = DVASPECT_CONTENT;
:    fmtetc.lindex = -1;
:    fmtetc.tymed = TYMED_HGLOBAL;
:
:    // does the drag source provide CF_TEXT?
:    if (SUCCEEDED(pDataObj->QueryGetData(&fmtetc)))
:    {
:         FAcceptFormat = true;
:         *pdwEffect = DROPEFFECT_COPY;
:    }
:    else
:    {
:       FAcceptFormat = false;
:       *pdwEffect = DROPEFFECT_NONE;
:    }
:    return NOERROR;
: }
:
: // modified (for CF_TEXT) Drop
: STDMETHODIMP TDropTarget::Drop(LPDATAOBJECT pDataObj, DWORD grfKeyState,
:     POINTL pt, LPDWORD pdwEffect)
: {
:    FORMATETC fmtetc;
:    fmtetc.cfFormat = CF_TEXT;
:    fmtetc.ptd = NULL;
:    fmtetc.dwAspect = DVASPECT_CONTENT;
:    fmtetc.lindex = -1;
:    fmtetc.tymed = TYMED_HGLOBAL;
:
:    // user has dropped on us -- get the CF_TEXT data from drag source
:    STGMEDIUM medium;
:    HRESULT hr = pDataObj->GetData(&fmtetc, &medium);
:
:    if (SUCCEEDED(hr))
:    {
:       // grab a pointer to the data
:       HGLOBAL HData = medium.hGlobal;
:       char* text = static_cast<char*>(GlobalLock(HData));
:       try
:       {
:          // call the helper routine which will
:          // notify the Form of the drop
:          HandleDrop(text);
:       }
:       catch (...)
:       {
:          // release the pointer to the memory
:          GlobalUnlock(HData);
:          ReleaseStgMedium(&medium);
:       }
:       // release the pointer to the memory
:       GlobalUnlock(HData);
:       ReleaseStgMedium(&medium);
:    }
:    else
:    {
:       *pdwEffect = DROPEFFECT_NONE;
:       return hr;
:    }
:    return NOERROR;
: }
:
:
: // in Form1 header...
: #include "DropTarget.h"
:
:    LPDROPTARGET lpDropTarget_;
:    void __fastcall WMOleDrop(TMessage& AMsg);
:
: BEGIN_MESSAGE_MAP
:    MESSAGE_HANDLER(WM_OLEDROP, TMessage, WMOleDrop)
: END_MESSAGE_MAP(TForm)
:
:
: // in Form1 source...
:
: __fastcall TForm1::TForm1(TComponent* Owner)
:    : TForm(Owner)
: {
:    // initialize the OLE library
:    OleInitialize(NULL);
:
:    // pass the handle to the Form in the constructor
:    // so TDropTarget knows which window to send the
:    // WM_OLEDROP message
:    lpDropTarget_ =
:       reinterpret_cast<LPDROPTARGET>(new TDropTarget(Handle));
:    CoLockObjectExternal(lpDropTarget_, true, true);
:
:    // register the Memo as a drop target
:    RegisterDragDrop(Memo1->Handle, lpDropTarget_);
: }
:
: __fastcall TForm1::~TForm1()
: {
:    // remove the Memo from the list of drop targets
:    RevokeDragDrop(Memo1->Handle);
:
:    // delete the TDropTarget instance
:    lpDropTarget_->Release();
:    CoLockObjectExternal(lpDropTarget_, false, true);
:
:    // uninitialize the OLE library
:    OleUninitialize();
: }
:
: void __fastcall TForm1::WMOleDrop(TMessage& AMsg)
: {
:    const char* text = reinterpret_cast<const char*>(AMsg.WParam);
:    Memo1->Lines->Add(text);
: }
:
:
: HTH.
:
: Damon C. (TeamB)
:
:
:
: 이기주 님이 쓰신 글 :
: : 탐색기에서 TreeView로 파일을 드래그 할 경우
: :
: : WM_DROPFILES메세지 처리를 하여 사용하고 있습니다.
: :
: : 하지만 이메세지는 마우스로 drop하였을 경우에만 발생되지
: :
: : 드래그 하는중에는 발생되지 않습니다.
: :
: : 제가 알고싶은것은 바로 drag하는 중인지를 어떻게 알아내는가 하는것입니다.
: :
: : 알고 계신분의 답변 부탁드립니다.
: :