IDROPSRC.CPP

/* 
 * IDROPSRC.CPP 
 * 
 * Template implementation of a DropSource object.  There is 
 * actually a full standard implementation of this interface here. 
 * 
 * Copyright (c)1993-1996 Microsoft Corporation, All Rights Reserved 
 * 
 * Kraig Brockschmidt, Software Design Engineer 
 * Microsoft Systems Developer Relations 
 * 
 * Internet  :  kraigb@microsoft.com 
 * Compuserve:  >INTERNET:kraigb@microsoft.com 
 */ 
 
 
#include "idropsrc.h" 
 
 
 
/* 
 * CDropSource::CDropSource 
 * CDropSource::~CDropSource 
 * 
 * Constructor Parameters: 
 *  pObj            LPVOID back pointer to whatever we live with. 
 */ 
 
CDropSource::CDropSource(LPVOID pBack) 
    { 
    m_cRef=0; 
    m_pBack=pBack; 
    return; 
    } 
 
 
CDropSource::~CDropSource(void) 
    { 
    return; 
    } 
 
 
 
 
/* 
 * CDropSource::QueryInterface 
 * CDropSource::AddRef 
 * CDropSource::Release 
 * 
 * Purpose: 
 *  Non-delegating IUnknown members for CDropSource. 
 */ 
 
STDMETHODIMP CDropSource::QueryInterface(REFIID riid 
    , LPVOID *ppv) 
    { 
    *ppv=NULL; 
 
    //Any interface on this object is the object pointer. 
    if (IsEqualIID(riid, IID_IUnknown) 
        || IsEqualIID(riid, IID_IDropSource)) 
        *ppv=(LPVOID)this; 
 
    /* 
     * If we actually assign an interface to ppv we need to AddRef 
     * it since we're returning a new pointer. 
     */ 
    if (NULL!=*ppv) 
        { 
        ((LPUNKNOWN)*ppv)->AddRef(); 
        return NOERROR; 
        } 
 
    return E_NOINTERFACE; 
    } 
 
 
STDMETHODIMP_(ULONG) CDropSource::AddRef(void) 
    { 
    return ++m_cRef; 
    } 
 
STDMETHODIMP_(ULONG) CDropSource::Release(void) 
    { 
    ULONG   cRefT; 
 
    cRefT=--m_cRef; 
 
    if (0L==m_cRef) 
        delete this; 
 
    return cRefT; 
    } 
 
 
 
 
 
/* 
 * CDropSource::QueryDragContinue 
 * 
 * Purpose: 
 *  Determines whether to continue a drag operation or cancel it. 
 * 
 * Parameters: 
 *  fEsc            BOOL indicating that the ESC key was pressed. 
 *  grfKeyState     DWORD providing states of keys and mouse buttons 
 * 
 * Return Value: 
 *  HRESULT         DRAGDROP_S_CANCEL to stop the drag, 
 *                  DRAGDROP_S_DROP to drop the data where it is, 
 *                  or NOERROR to continue. 
 */ 
 
STDMETHODIMP CDropSource::QueryContinueDrag(BOOL fEsc 
    , DWORD grfKeyState) 
    { 
    if (fEsc) 
        return DRAGDROP_S_CANCEL; 
 
    if (!(grfKeyState & MK_LBUTTON)) 
        return DRAGDROP_S_DROP; 
 
    return NOERROR; 
    } 
 
 
 
 
 
 
/* 
 * CDropSource::GiveFeedback 
 * 
 * Purpose: 
 *  Provides cursor feedback to the user since the source task 
 *  always has the mouse capture.  We can also provide any other 
 *  type of feedback above cursors if we so desire. 
 * 
 * Parameters: 
 *  dwEffect        DWORD effect flags returned from the last target 
 * 
 * Return Value: 
 *  HRESULT         NOERROR if you set a cursor yourself or 
 *                  DRAGDROP_S_USEDEFAULTCURSORS to let OLE do 
 *                  the work. 
 */ 
 
STDMETHODIMP CDropSource::GiveFeedback(DWORD dwEffect) 
    { 
    return DRAGDROP_S_USEDEFAULTCURSORS; 
    }