DROPTGT.CPP

/* 
 * DROPTGT.CPP 
 * Component Cosmo Chapter 13 
 * 
 * Implementation of the DropTarget object. 
 * 
 * Copyright (c)1993-1995 Microsoft Corporation, All Rights Reserved 
 * 
 * Kraig Brockschmidt, Microsoft 
 * Internet  :  kraigb@microsoft.com 
 * Compuserve:  >INTERNET:kraigb@microsoft.com 
 */ 
 
 
#include "cocosmo.h" 
 
 
 
/* 
 * CDropTarget::CDropTarget 
 * CDropTarget::~CDropTarget 
 * 
 * Constructor Parameters: 
 *  pDoc            PCCosmoDoc of the document containing us. 
 */ 
 
CDropTarget::CDropTarget(PCCosmoDoc pDoc) 
    { 
    m_cRef=0; 
    m_pDoc=pDoc; 
 
    m_pIDataObject=NULL; 
    return; 
    } 
 
 
CDropTarget::~CDropTarget(void) 
    { 
    return; 
    } 
 
 
 
 
/* 
 * CDropTarget::QueryInterface 
 * CDropTarget::AddRef 
 * CDropTarget::Release 
 * 
 * Purpose: 
 *  IUnknown members for CDropTarget object. 
 */ 
 
STDMETHODIMP CDropTarget::QueryInterface(REFIID riid, PPVOID ppv) 
    { 
    *ppv=NULL; 
 
    if (IID_IUnknown==riid || IID_IDropTarget==riid) 
        *ppv=this; 
 
    if (NULL!=*ppv) 
        { 
        ((LPUNKNOWN)*ppv)->AddRef(); 
        return NOERROR; 
        } 
 
    return ResultFromScode(E_NOINTERFACE); 
    } 
 
 
STDMETHODIMP_(ULONG) CDropTarget::AddRef(void) 
    { 
    return ++m_cRef; 
    } 
 
STDMETHODIMP_(ULONG) CDropTarget::Release(void) 
    { 
     if (0!=--m_cRef) 
        return m_cRef; 
 
    delete this; 
    return 0; 
    } 
 
 
 
 
 
/* 
 * CDropTarget::DragEnter 
 * 
 * Purpose: 
 *  Indicates that data in a drag operation has been dragged over 
 *  our window that's a potential target.  We are to decide if it's 
 *  something in which we're interested. 
 * 
 * Parameters: 
 *  pIDataSource    LPDATAOBJECT providing the source data. 
 *  grfKeyState     DWORD flags: states of keys and mouse buttons. 
 *  pt              POINTL coordinates in the client space of 
 *                  the document. 
 *  pdwEffect       LPDWORD into which we'll place the appropriate 
 *                  effect flag for this point. 
 * 
 * Return Value: 
 *  HRESULT         NOERROR 
 */ 
 
STDMETHODIMP CDropTarget::DragEnter(LPDATAOBJECT pIDataSource 
    , DWORD grfKeyState, POINTL pt, LPDWORD pdwEffect) 
    { 
    HWND        hWnd; 
 
    m_pIDataObject=NULL; 
 
    if (!m_pDoc->FQueryPasteFromData(pIDataSource)) 
        { 
        *pdwEffect=DROPEFFECT_NONE; 
        return NOERROR; 
        } 
 
    *pdwEffect=DROPEFFECT_MOVE; 
 
    if (grfKeyState & MK_CONTROL) 
        *pdwEffect=DROPEFFECT_COPY; 
 
    m_pIDataObject=pIDataSource; 
    m_pIDataObject->AddRef(); 
 
    hWnd=m_pDoc->Window(); 
    BringWindowToTop(hWnd); 
    UpdateWindow(hWnd); 
    m_pDoc->DropSelectTargetWindow(); 
 
    return NOERROR; 
    } 
 
 
 
 
 
 
/* 
 * CDropTarget::DragOver 
 * 
 * Purpose: 
 *  Indicates that the mouse was moved inside the window represented 
 *  by this drop target.  This happens on every WM_MOUSEMOVE, so 
 *  this function should be very efficient. 
 * 
 * Parameters: 
 *  grfKeyState     DWORD providing the current keyboard and 
 *                  mouse states 
 *  pt              POINTL where the mouse currently is. 
 *  pdwEffect       LPDWORD in which to store the effect flag 
 *                  for this point. 
 * 
 * Return Value: 
 *  HRESULT         NOERROR 
 */ 
 
STDMETHODIMP CDropTarget::DragOver(DWORD grfKeyState, POINTL pt 
    , LPDWORD pdwEffect) 
    { 
    if (NULL==m_pIDataObject) 
        { 
        *pdwEffect=DROPEFFECT_NONE; 
        return NOERROR; 
        } 
 
    *pdwEffect=DROPEFFECT_MOVE; 
 
    if (grfKeyState & MK_CONTROL) 
        *pdwEffect=DROPEFFECT_COPY; 
 
    return NOERROR; 
    } 
 
 
 
 
 
 
/* 
 * CDropTarget::DragLeave 
 * 
 * Purpose: 
 *  Informs the drop target that the operation has left its window. 
 * 
 * Parameters: 
 *  None 
 * 
 * Return Value: 
 *  HRESULT         NOERROR 
 */ 
 
STDMETHODIMP CDropTarget::DragLeave(void) 
    { 
    m_pDoc->DropSelectTargetWindow(); 
    ReleaseInterface(m_pIDataObject); 
    return NOERROR; 
    } 
 
 
 
 
 
/* 
 * CDropTarget::Drop 
 * 
 * Purpose: 
 *  Instructs the drop target to paste the data that was just now 
 *  dropped on it. 
 * 
 * Parameters: 
 *  pIDataSource    LPDATAOBJECT from which we'll paste. 
 *  grfKeyState     DWORD providing current keyboard/mouse state. 
 *  pt              POINTL at which the drop occurred. 
 *  pdwEffect       LPDWORD in which to store what you did. 
 * 
 * Return Value: 
 *  HRESULT         NOERROR 
 */ 
 
STDMETHODIMP CDropTarget::Drop(LPDATAOBJECT pIDataSource 
    , DWORD grfKeyState, POINTL pt, LPDWORD pdwEffect) 
    { 
    BOOL        fRet=TRUE; 
 
    *pdwEffect=DROPEFFECT_NONE; 
 
    if (NULL==m_pIDataObject) 
        return ResultFromScode(E_FAIL); 
 
    DragLeave(); 
 
    if (m_pDoc->m_fDragSource) 
        return ResultFromScode(E_FAIL); 
 
    fRet=m_pDoc->PasteFromData(pIDataSource); 
 
    if (!fRet) 
        return ResultFromScode(E_FAIL); 
 
    *pdwEffect=DROPEFFECT_MOVE; 
 
    if (grfKeyState & MK_CONTROL) 
        *pdwEffect=DROPEFFECT_COPY; 
 
    return NOERROR; 
    }