src/msw/ole/droptgt.cpp

   1 ///////////////////////////////////////////////////////////////////////////////
   2 // Name:        src/msw/ole/droptgt.cpp
   3 // Purpose:     wxDropTarget implementation
   4 // Author:      Vadim Zeitlin
   5 // Modified by:
   6 // Created:
   7 // Copyright:   (c) 1998 Vadim Zeitlin <zeitlin@dptmaths.ens-cachan.fr>
   8 // Licence:     wxWindows licence
   9 ///////////////////////////////////////////////////////////////////////////////
  10
  11 // ============================================================================
  12 // Declarations
  13 // ============================================================================
  14
  15 // ----------------------------------------------------------------------------
  16 // headers
  17 // ----------------------------------------------------------------------------
  18
  19 // For compilers that support precompilation, includes "wx.h".
  20 #include "wx/wxprec.h"
  21
  22 #if defined(__BORLANDC__)
  23     #pragma hdrstop
  24 #endif
  25
  26 #if wxUSE_OLE && wxUSE_DRAG_AND_DROP
  27
  28 #ifndef WX_PRECOMP
  29     #include "wx/msw/wrapwin.h"
  30     #include "wx/log.h"
  31 #endif
  32
  33 #include "wx/msw/private.h"
  34
  35 #ifdef __WXWINCE__
  36     #include <winreg.h>
  37     #include <ole2.h>
  38 #endif
  39
  40 #ifdef __WIN32__
  41     #if !defined(__GNUWIN32__) || wxUSE_NORLANDER_HEADERS
  42         #include <shlobj.h>            // for DROPFILES structure
  43     #endif
  44 #else
  45     #include <shellapi.h>
  46 #endif
  47
  48 #include "wx/dnd.h"
  49
  50 #include "wx/msw/ole/oleutils.h"
  51
  52 #include <initguid.h>
  53
  54 // Some (very) old SDKs don't define IDropTargetHelper, so define our own
  55 // version of it here.
  56 struct wxIDropTargetHelper : public IUnknown
  57 {
  58     virtual HRESULT STDMETHODCALLTYPE DragEnter(HWND hwndTarget,
  59                                                 IDataObject *pDataObject,
  60                                                 POINT *ppt,
  61                                                 DWORD dwEffect) = 0;
  62     virtual HRESULT STDMETHODCALLTYPE DragLeave() = 0;
  63     virtual HRESULT STDMETHODCALLTYPE DragOver(POINT *ppt, DWORD dwEffect) = 0;
  64     virtual HRESULT STDMETHODCALLTYPE Drop(IDataObject *pDataObject,
  65                                            POINT *ppt,
  66                                            DWORD dwEffect) = 0;
  67     virtual HRESULT STDMETHODCALLTYPE Show(BOOL fShow) = 0;
  68 };
  69
  70 namespace
  71 {
  72     DEFINE_GUID(wxCLSID_DragDropHelper,
  73                 0x4657278A,0x411B,0x11D2,0x83,0x9A,0x00,0xC0,0x4F,0xD9,0x18,0xD0);
  74     DEFINE_GUID(wxIID_IDropTargetHelper,
  75                 0x4657278B,0x411B,0x11D2,0x83,0x9A,0x00,0xC0,0x4F,0xD9,0x18,0xD0);
  76 }
  77
  78 // ----------------------------------------------------------------------------
  79 // IDropTarget interface: forward all interesting things to wxDropTarget
  80 // (the name is unfortunate, but wx_I_DropTarget is not at all the same thing
  81 //  as wxDropTarget which is 'public' class, while this one is private)
  82 // ----------------------------------------------------------------------------
  83
  84 class wxIDropTarget : public IDropTarget
  85 {
  86 public:
  87     wxIDropTarget(wxDropTarget *p);
  88     virtual ~wxIDropTarget();
  89
  90     // accessors for wxDropTarget
  91     HWND GetHWND() const { return m_hwnd; }
  92     void SetHwnd(HWND hwnd) { m_hwnd = hwnd; }
  93
  94     // IDropTarget methods
  95     STDMETHODIMP DragEnter(LPDATAOBJECT, DWORD, POINTL, LPDWORD);
  96     STDMETHODIMP DragOver(DWORD, POINTL, LPDWORD);
  97     STDMETHODIMP DragLeave();
  98     STDMETHODIMP Drop(LPDATAOBJECT, DWORD, POINTL, LPDWORD);
  99
 100     DECLARE_IUNKNOWN_METHODS;
 101
 102 protected:
 103     IDataObject  *m_pIDataObject; // !NULL between DragEnter and DragLeave/Drop
 104     wxDropTarget *m_pTarget;      // the real target (we're just a proxy)
 105
 106     HWND          m_hwnd;         // window we're associated with
 107
 108     // get default drop effect for given keyboard flags
 109     static DWORD GetDropEffect(DWORD flags, wxDragResult defaultAction, DWORD pdwEffect);
 110
 111     wxDECLARE_NO_COPY_CLASS(wxIDropTarget);
 112 };
 113
 114 // ----------------------------------------------------------------------------
 115 // private functions
 116 // ----------------------------------------------------------------------------
 117
 118 static wxDragResult ConvertDragEffectToResult(DWORD dwEffect);
 119 static DWORD ConvertDragResultToEffect(wxDragResult result);
 120
 121 // ============================================================================
 122 // wxIDropTarget implementation
 123 // ============================================================================
 124
 125 // Name    : static wxIDropTarget::GetDropEffect
 126 // Purpose : determine the drop operation from keyboard/mouse state.
 127 // Returns : DWORD combined from DROPEFFECT_xxx constants
 128 // Params  : [in] DWORD flags                 kbd & mouse flags as passed to
 129 //                                            IDropTarget methods
 130 //           [in] wxDragResult defaultAction  the default action of the drop target
 131 //           [in] DWORD pdwEffect             the supported actions of the drop
 132 //                                            source passed to IDropTarget methods
 133 // Notes   : We do "move" normally and "copy" if <Ctrl> is pressed,
 134 //           which is the standard behaviour (currently there is no
 135 //           way to redefine it)
 136 DWORD wxIDropTarget::GetDropEffect(DWORD flags,
 137                                    wxDragResult defaultAction,
 138                                    DWORD pdwEffect)
 139 {
 140     DWORD effectiveAction;
 141     if ( defaultAction == wxDragCopy )
 142         effectiveAction = flags & MK_SHIFT ? DROPEFFECT_MOVE : DROPEFFECT_COPY;
 143     else
 144         effectiveAction = flags & MK_CONTROL ? DROPEFFECT_COPY : DROPEFFECT_MOVE;
 145
 146     if ( !(effectiveAction & pdwEffect) )
 147     {
 148         // the action is not supported by drag source, fall back to something
 149         // that it does support
 150         if ( pdwEffect & DROPEFFECT_MOVE )
 151             effectiveAction = DROPEFFECT_MOVE;
 152         else if ( pdwEffect & DROPEFFECT_COPY )
 153             effectiveAction = DROPEFFECT_COPY;
 154         else if ( pdwEffect & DROPEFFECT_LINK )
 155             effectiveAction = DROPEFFECT_LINK;
 156         else
 157             effectiveAction = DROPEFFECT_NONE;
 158     }
 159
 160     return effectiveAction;
 161 }
 162
 163 wxIDropTarget::wxIDropTarget(wxDropTarget *pTarget)
 164 {
 165   m_pTarget      = pTarget;
 166   m_pIDataObject = NULL;
 167 }
 168
 169 wxIDropTarget::~wxIDropTarget()
 170 {
 171 }
 172
 173 BEGIN_IID_TABLE(wxIDropTarget)
 174   ADD_IID(Unknown)
 175   ADD_IID(DropTarget)
 176 END_IID_TABLE;
 177
 178 IMPLEMENT_IUNKNOWN_METHODS(wxIDropTarget)
 179
 180 // Name    : wxIDropTarget::DragEnter
 181 // Purpose : Called when the mouse enters the window (dragging something)
 182 // Returns : S_OK
 183 // Params  : [in]    IDataObject *pIDataSource : source data
 184 //           [in]    DWORD        grfKeyState  : kbd & mouse state
 185 //           [in]    POINTL       pt           : mouse coordinates
 186 //           [in/out]DWORD       *pdwEffect    : effect flag
 187 //                                               In:  Supported effects
 188 //                                               Out: Resulting effect
 189 // Notes   :
 190 STDMETHODIMP wxIDropTarget::DragEnter(IDataObject *pIDataSource,
 191                                       DWORD        grfKeyState,
 192                                       POINTL       pt,
 193                                       DWORD       *pdwEffect)
 194 {
 195     wxLogTrace(wxTRACE_OleCalls, wxT("IDropTarget::DragEnter"));
 196
 197     wxASSERT_MSG( m_pIDataObject == NULL,
 198                   wxT("drop target must have data object") );
 199
 200     // show the list of formats supported by the source data object for the
 201     // debugging purposes, this is quite useful sometimes - please don't remove
 202 #if 0
 203     IEnumFORMATETC *penumFmt;
 204     if ( SUCCEEDED(pIDataSource->EnumFormatEtc(DATADIR_GET, &penumFmt)) )
 205     {
 206         FORMATETC fmt;
 207         while ( penumFmt->Next(1, &fmt, NULL) == S_OK )
 208         {
 209             wxLogDebug(wxT("Drop source supports format %s"),
 210                        wxDataObject::GetFormatName(fmt.cfFormat));
 211         }
 212
 213         penumFmt->Release();
 214     }
 215     else
 216     {
 217         wxLogLastError(wxT("IDataObject::EnumFormatEtc"));
 218     }
 219 #endif // 0
 220
 221     // for use in OnEnter and OnDrag calls
 222     m_pTarget->MSWSetDataSource(pIDataSource);
 223
 224     // get hold of the data object
 225     m_pIDataObject = pIDataSource;
 226     m_pIDataObject->AddRef();
 227
 228     if ( !m_pTarget->MSWIsAcceptedData(pIDataSource) ) {
 229         // we don't accept this kind of data
 230         *pdwEffect = DROPEFFECT_NONE;
 231     }
 232     else
 233     {
 234         // we need client coordinates to pass to wxWin functions
 235         if ( !ScreenToClient(m_hwnd, (POINT *)&pt) )
 236         {
 237             wxLogLastError(wxT("ScreenToClient"));
 238         }
 239
 240         // give some visual feedback
 241         *pdwEffect = ConvertDragResultToEffect(
 242             m_pTarget->OnEnter(pt.x, pt.y, ConvertDragEffectToResult(
 243                 GetDropEffect(grfKeyState, m_pTarget->GetDefaultAction(), *pdwEffect))
 244                         )
 245                      );
 246     }
 247
 248     // update drag image
 249     const wxDragResult res = ConvertDragEffectToResult(*pdwEffect);
 250     m_pTarget->MSWUpdateDragImageOnEnter(pt.x, pt.y, res);
 251     m_pTarget->MSWUpdateDragImageOnDragOver(pt.x, pt.y, res);
 252
 253     return S_OK;
 254 }
 255
 256
 257
 258 // Name    : wxIDropTarget::DragOver
 259 // Purpose : Indicates that the mouse was moved inside the window represented
 260 //           by this drop target.
 261 // Returns : S_OK
 262 // Params  : [in]    DWORD   grfKeyState     kbd & mouse state
 263 //           [in]    POINTL  pt              mouse coordinates
 264 //           [in/out]LPDWORD pdwEffect       current effect flag
 265 // Notes   : We're called on every WM_MOUSEMOVE, so this function should be
 266 //           very efficient.
 267 STDMETHODIMP wxIDropTarget::DragOver(DWORD   grfKeyState,
 268                                      POINTL  pt,
 269                                      LPDWORD pdwEffect)
 270 {
 271     // there are too many of them... wxLogDebug("IDropTarget::DragOver");
 272
 273     wxDragResult result;
 274     if ( m_pIDataObject ) {
 275         result = ConvertDragEffectToResult(
 276             GetDropEffect(grfKeyState, m_pTarget->GetDefaultAction(), *pdwEffect));
 277     }
 278     else {
 279         // can't accept data anyhow normally
 280         result = wxDragNone;
 281     }
 282
 283     if ( result != wxDragNone ) {
 284         // we need client coordinates to pass to wxWin functions
 285         if ( !ScreenToClient(m_hwnd, (POINT *)&pt) )
 286         {
 287             wxLogLastError(wxT("ScreenToClient"));
 288         }
 289
 290         *pdwEffect = ConvertDragResultToEffect(
 291                         m_pTarget->OnDragOver(pt.x, pt.y, result)
 292                      );
 293     }
 294     else {
 295         *pdwEffect = DROPEFFECT_NONE;
 296     }
 297
 298     // update drag image
 299     m_pTarget->MSWUpdateDragImageOnDragOver(pt.x, pt.y,
 300                                             ConvertDragEffectToResult(*pdwEffect));
 301
 302     return S_OK;
 303 }
 304
 305 // Name    : wxIDropTarget::DragLeave
 306 // Purpose : Informs the drop target that the operation has left its window.
 307 // Returns : S_OK
 308 // Notes   : good place to do any clean-up
 309 STDMETHODIMP wxIDropTarget::DragLeave()
 310 {
 311   wxLogTrace(wxTRACE_OleCalls, wxT("IDropTarget::DragLeave"));
 312
 313   // remove the UI feedback
 314   m_pTarget->OnLeave();
 315
 316   // release the held object
 317   RELEASE_AND_NULL(m_pIDataObject);
 318
 319   // update drag image
 320   m_pTarget->MSWUpdateDragImageOnLeave();
 321
 322   return S_OK;
 323 }
 324
 325 // Name    : wxIDropTarget::Drop
 326 // Purpose : Instructs the drop target to paste data that was just now
 327 //           dropped on it.
 328 // Returns : S_OK
 329 // Params  : [in]    IDataObject *pIDataSource     the data to paste
 330 //           [in]    DWORD        grfKeyState      kbd & mouse state
 331 //           [in]    POINTL       pt               where the drop occurred?
 332 //           [in/out]DWORD       *pdwEffect        operation effect
 333 // Notes   :
 334 STDMETHODIMP wxIDropTarget::Drop(IDataObject *pIDataSource,
 335                                  DWORD        grfKeyState,
 336                                  POINTL       pt,
 337                                  DWORD       *pdwEffect)
 338 {
 339     wxLogTrace(wxTRACE_OleCalls, wxT("IDropTarget::Drop"));
 340
 341     // TODO I don't know why there is this parameter, but so far I assume
 342     //      that it's the same we've already got in DragEnter
 343     wxASSERT( m_pIDataObject == pIDataSource );
 344
 345     // we need client coordinates to pass to wxWin functions
 346     if ( !ScreenToClient(m_hwnd, (POINT *)&pt) )
 347     {
 348         wxLogLastError(wxT("ScreenToClient"));
 349     }
 350
 351     // first ask the drop target if it wants data
 352     if ( m_pTarget->OnDrop(pt.x, pt.y) ) {
 353         // it does, so give it the data source
 354         m_pTarget->MSWSetDataSource(pIDataSource);
 355
 356         // and now it has the data
 357         wxDragResult rc = ConvertDragEffectToResult(
 358             GetDropEffect(grfKeyState, m_pTarget->GetDefaultAction(), *pdwEffect));
 359         rc = m_pTarget->OnData(pt.x, pt.y, rc);
 360         if ( wxIsDragResultOk(rc) ) {
 361             // operation succeeded
 362             *pdwEffect = ConvertDragResultToEffect(rc);
 363         }
 364         else {
 365             *pdwEffect = DROPEFFECT_NONE;
 366         }
 367     }
 368     else {
 369         // OnDrop() returned false, no need to copy data
 370         *pdwEffect = DROPEFFECT_NONE;
 371     }
 372
 373     // release the held object
 374     RELEASE_AND_NULL(m_pIDataObject);
 375
 376     // update drag image
 377     m_pTarget->MSWUpdateDragImageOnData(pt.x, pt.y,
 378                                         ConvertDragEffectToResult(*pdwEffect));
 379
 380     return S_OK;
 381 }
 382
 383 // ============================================================================
 384 // wxDropTarget implementation
 385 // ============================================================================
 386
 387 // ----------------------------------------------------------------------------
 388 // ctor/dtor
 389 // ----------------------------------------------------------------------------
 390
 391 wxDropTarget::wxDropTarget(wxDataObject *dataObj)
 392             : wxDropTargetBase(dataObj),
 393               m_dropTargetHelper(NULL)
 394 {
 395     // create an IDropTarget implementation which will notify us about d&d
 396     // operations.
 397     m_pIDropTarget = new wxIDropTarget(this);
 398     m_pIDropTarget->AddRef();
 399 }
 400
 401 wxDropTarget::~wxDropTarget()
 402 {
 403     ReleaseInterface(m_pIDropTarget);
 404 }
 405
 406 // ----------------------------------------------------------------------------
 407 // [un]register drop handler
 408 // ----------------------------------------------------------------------------
 409
 410 bool wxDropTarget::Register(WXHWND hwnd)
 411 {
 412     // FIXME
 413     // RegisterDragDrop not available on Windows CE >= 400?
 414     // Or maybe we can dynamically load them from ceshell.dll
 415     // or similar.
 416 #if defined(__WXWINCE__) && _WIN32_WCE >= 400
 417     wxUnusedVar(hwnd);
 418     return false;
 419 #else
 420     HRESULT hr;
 421
 422     // May exist in later WinCE versions
 423 #ifndef __WXWINCE__
 424     hr = ::CoLockObjectExternal(m_pIDropTarget, TRUE, FALSE);
 425     if ( FAILED(hr) ) {
 426         wxLogApiError(wxT("CoLockObjectExternal"), hr);
 427         return false;
 428     }
 429 #endif
 430
 431     hr = ::RegisterDragDrop((HWND) hwnd, m_pIDropTarget);
 432     if ( FAILED(hr) ) {
 433     // May exist in later WinCE versions
 434 #ifndef __WXWINCE__
 435         ::CoLockObjectExternal(m_pIDropTarget, FALSE, FALSE);
 436 #endif
 437         wxLogApiError(wxT("RegisterDragDrop"), hr);
 438         return false;
 439     }
 440
 441     // we will need the window handle for coords transformation later
 442     m_pIDropTarget->SetHwnd((HWND)hwnd);
 443
 444     MSWInitDragImageSupport();
 445
 446     return true;
 447 #endif
 448 }
 449
 450 void wxDropTarget::Revoke(WXHWND hwnd)
 451 {
 452 #if defined(__WXWINCE__) && _WIN32_WCE >= 400
 453     // Not available, see note above
 454     wxUnusedVar(hwnd);
 455 #else
 456     HRESULT hr = ::RevokeDragDrop((HWND) hwnd);
 457
 458     if ( FAILED(hr) ) {
 459         wxLogApiError(wxT("RevokeDragDrop"), hr);
 460     }
 461
 462     // May exist in later WinCE versions
 463 #ifndef __WXWINCE__
 464     ::CoLockObjectExternal(m_pIDropTarget, FALSE, TRUE);
 465 #endif
 466
 467     MSWEndDragImageSupport();
 468
 469     // remove window reference
 470     m_pIDropTarget->SetHwnd(0);
 471 #endif
 472 }
 473
 474 // ----------------------------------------------------------------------------
 475 // base class pure virtuals
 476 // ----------------------------------------------------------------------------
 477
 478 // OnDrop() is called only if we previously returned true from
 479 // IsAcceptedData(), so no need to check anything here
 480 bool wxDropTarget::OnDrop(wxCoord WXUNUSED(x), wxCoord WXUNUSED(y))
 481 {
 482     return true;
 483 }
 484
 485 // copy the data from the data source to the target data object
 486 bool wxDropTarget::GetData()
 487 {
 488     wxDataFormat format = MSWGetSupportedFormat(m_pIDataSource);
 489     if ( format == wxDF_INVALID ) {
 490         return false;
 491     }
 492
 493     STGMEDIUM stm;
 494     FORMATETC fmtMemory;
 495     fmtMemory.cfFormat  = format;
 496     fmtMemory.ptd       = NULL;
 497     fmtMemory.dwAspect  = DVASPECT_CONTENT;
 498     fmtMemory.lindex    = -1;
 499     fmtMemory.tymed     = TYMED_HGLOBAL;  // TODO to add other media
 500
 501     bool rc = false;
 502
 503     HRESULT hr = m_pIDataSource->GetData(&fmtMemory, &stm);
 504     if ( SUCCEEDED(hr) ) {
 505         IDataObject *dataObject = m_dataObject->GetInterface();
 506
 507         hr = dataObject->SetData(&fmtMemory, &stm, TRUE);
 508         if ( SUCCEEDED(hr) ) {
 509             rc = true;
 510         }
 511         else {
 512             wxLogApiError(wxT("IDataObject::SetData()"), hr);
 513         }
 514     }
 515     else {
 516         wxLogApiError(wxT("IDataObject::GetData()"), hr);
 517     }
 518
 519     return rc;
 520 }
 521
 522 // ----------------------------------------------------------------------------
 523 // callbacks used by wxIDropTarget
 524 // ----------------------------------------------------------------------------
 525
 526 // we need a data source, so wxIDropTarget gives it to us using this function
 527 void wxDropTarget::MSWSetDataSource(IDataObject *pIDataSource)
 528 {
 529     m_pIDataSource = pIDataSource;
 530 }
 531
 532 // determine if we accept data of this type
 533 bool wxDropTarget::MSWIsAcceptedData(IDataObject *pIDataSource) const
 534 {
 535     return MSWGetSupportedFormat(pIDataSource) != wxDF_INVALID;
 536 }
 537
 538 // ----------------------------------------------------------------------------
 539 // helper functions
 540 // ----------------------------------------------------------------------------
 541
 542 wxDataFormat wxDropTarget::GetMatchingPair()
 543 {
 544     return MSWGetSupportedFormat( m_pIDataSource );
 545 }
 546
 547 wxDataFormat wxDropTarget::MSWGetSupportedFormat(IDataObject *pIDataSource) const
 548 {
 549     // this strucutre describes a data of any type (first field will be
 550     // changing) being passed through global memory block.
 551     static FORMATETC s_fmtMemory = {
 552         0,
 553         NULL,
 554         DVASPECT_CONTENT,
 555         -1,
 556         TYMED_HGLOBAL       // TODO is it worth supporting other tymeds here?
 557     };
 558
 559     // get the list of supported formats
 560     size_t nFormats = m_dataObject->GetFormatCount(wxDataObject::Set);
 561     wxDataFormat format;
 562     wxDataFormat *formats;
 563     formats = nFormats == 1 ? &format :  new wxDataFormat[nFormats];
 564
 565     m_dataObject->GetAllFormats(formats, wxDataObject::Set);
 566
 567     // cycle through all supported formats
 568     size_t n;
 569     for ( n = 0; n < nFormats; n++ ) {
 570         s_fmtMemory.cfFormat = formats[n];
 571
 572         // NB: don't use SUCCEEDED macro here: QueryGetData returns S_FALSE
 573         //     for file drag and drop (format == CF_HDROP)
 574         if ( pIDataSource->QueryGetData(&s_fmtMemory) == S_OK ) {
 575             format = formats[n];
 576
 577             break;
 578         }
 579     }
 580
 581     if ( formats != &format ) {
 582         // free memory if we allocated it
 583         delete [] formats;
 584     }
 585
 586     return n < nFormats ? format : wxFormatInvalid;
 587 }
 588
 589 // ----------------------------------------------------------------------------
 590 // drag image functions
 591 // ----------------------------------------------------------------------------
 592
 593 void
 594 wxDropTarget::MSWEndDragImageSupport()
 595 {
 596     // release drop target helper
 597     if ( m_dropTargetHelper != NULL )
 598     {
 599         m_dropTargetHelper->Release();
 600         m_dropTargetHelper = NULL;
 601     }
 602 }
 603
 604 void
 605 wxDropTarget::MSWInitDragImageSupport()
 606 {
 607     // Use the default drop target helper to show shell drag images
 608     CoCreateInstance(wxCLSID_DragDropHelper, NULL, CLSCTX_INPROC_SERVER,
 609                      wxIID_IDropTargetHelper, (LPVOID*)&m_dropTargetHelper);
 610 }
 611
 612 void
 613 wxDropTarget::MSWUpdateDragImageOnData(wxCoord x,
 614                                        wxCoord y,
 615                                        wxDragResult dragResult)
 616 {
 617     // call corresponding event on drop target helper
 618     if ( m_dropTargetHelper != NULL )
 619     {
 620         POINT pt = {x, y};
 621         DWORD dwEffect = ConvertDragResultToEffect(dragResult);
 622         m_dropTargetHelper->Drop(m_pIDataSource, &pt, dwEffect);
 623     }
 624 }
 625
 626 void
 627 wxDropTarget::MSWUpdateDragImageOnDragOver(wxCoord x,
 628                                            wxCoord y,
 629                                            wxDragResult dragResult)
 630 {
 631     // call corresponding event on drop target helper
 632     if ( m_dropTargetHelper != NULL )
 633     {
 634         POINT pt = {x, y};
 635         DWORD dwEffect = ConvertDragResultToEffect(dragResult);
 636         m_dropTargetHelper->DragOver(&pt, dwEffect);
 637     }
 638 }
 639
 640 void
 641 wxDropTarget::MSWUpdateDragImageOnEnter(wxCoord x,
 642                                         wxCoord y,
 643                                         wxDragResult dragResult)
 644 {
 645     // call corresponding event on drop target helper
 646     if ( m_dropTargetHelper != NULL )
 647     {
 648         POINT pt = {x, y};
 649         DWORD dwEffect = ConvertDragResultToEffect(dragResult);
 650         m_dropTargetHelper->DragEnter(m_pIDropTarget->GetHWND(), m_pIDataSource, &pt, dwEffect);
 651     }
 652 }
 653
 654 void
 655 wxDropTarget::MSWUpdateDragImageOnLeave()
 656 {
 657     // call corresponding event on drop target helper
 658     if ( m_dropTargetHelper != NULL )
 659     {
 660         m_dropTargetHelper->DragLeave();
 661     }
 662 }
 663
 664 // ----------------------------------------------------------------------------
 665 // private functions
 666 // ----------------------------------------------------------------------------
 667
 668 static wxDragResult ConvertDragEffectToResult(DWORD dwEffect)
 669 {
 670     switch ( dwEffect ) {
 671         case DROPEFFECT_COPY:
 672             return wxDragCopy;
 673
 674         case DROPEFFECT_LINK:
 675             return wxDragLink;
 676
 677         case DROPEFFECT_MOVE:
 678             return wxDragMove;
 679
 680         default:
 681             wxFAIL_MSG(wxT("invalid value in ConvertDragEffectToResult"));
 682             // fall through
 683
 684         case DROPEFFECT_NONE:
 685             return wxDragNone;
 686     }
 687 }
 688
 689 static DWORD ConvertDragResultToEffect(wxDragResult result)
 690 {
 691     switch ( result ) {
 692         case wxDragCopy:
 693             return DROPEFFECT_COPY;
 694
 695         case wxDragLink:
 696             return DROPEFFECT_LINK;
 697
 698         case wxDragMove:
 699             return DROPEFFECT_MOVE;
 700
 701         default:
 702             wxFAIL_MSG(wxT("invalid value in ConvertDragResultToEffect"));
 703             // fall through
 704
 705         case wxDragNone:
 706             return DROPEFFECT_NONE;
 707     }
 708 }
 709
 710 #endif // wxUSE_OLE && wxUSE_DRAG_AND_DROP