IENUMFE.CPP

/* 
 * IENUMFE.CPP 
 * Data Object Chapter 10 
 * 
 * Standard implementation of a FORMATETC enumerator with the 
 * IEnumFORMATETC interface that will generally not need 
 * modification. 
 * 
 * Copyright (c)1993-1995 Microsoft Corporation, All Rights Reserved 
 * 
 * Kraig Brockschmidt, Microsoft 
 * Internet  :  kraigb@microsoft.com 
 * Compuserve:  >INTERNET:kraigb@microsoft.com 
 */ 
 
 
#include "dataobj.h" 
 
 
/* 
 * CEnumFormatEtc::CEnumFormatEtc 
 * CEnumFormatEtc::~CEnumFormatEtc 
 * 
 * Parameters (Constructor): 
 *  cFE             ULONG number of FORMATETCs in pFE 
 *  prgFE           LPFORMATETC to the array to enumerate. 
 */ 
 
CEnumFormatEtc::CEnumFormatEtc(ULONG cFE, LPFORMATETC prgFE) 
    { 
    UINT        i; 
 
    m_cRef=0; 
    m_iCur=0; 
    m_cfe=cFE; 
    m_prgfe=new FORMATETC[(UINT)cFE]; 
 
    if (NULL!=m_prgfe) 
        { 
        for (i=0; i < cFE; i++) 
            m_prgfe[i]=prgFE[i]; 
        } 
 
    return; 
    } 
 
 
CEnumFormatEtc::~CEnumFormatEtc(void) 
    { 
    if (NULL!=m_prgfe) 
        delete [] m_prgfe; 
 
    return; 
    } 
 
 
 
 
 
 
/* 
 * CEnumFormatEtc::QueryInterface 
 * CEnumFormatEtc::AddRef 
 * CEnumFormatEtc::Release 
 * 
 * Purpose: 
 *  IUnknown members for CEnumFormatEtc object.  For QueryInterface 
 *  we only return out own interfaces and not those of the data 
 *  object.  However, since enumerating formats only makes sense 
 *  when the data object is around, we insure that it stays as 
 *  long as we stay by calling an outer IUnknown for AddRef 
 *  and Release.  But since we are not controlled by the lifetime 
 *  of the outer object, we still keep our own reference count in 
 *  order to free ourselves. 
 */ 
 
STDMETHODIMP CEnumFormatEtc::QueryInterface(REFIID riid, PPVOID ppv) 
    { 
    *ppv=NULL; 
 
    /* 
     * Enumerators are separate objects, not the data object, so 
     * we only need to support out IUnknown and IEnumFORMATETC 
     * interfaces here with no concern for aggregation. 
     */ 
    if (IID_IUnknown==riid || IID_IEnumFORMATETC==riid) 
        *ppv=this; 
 
    //AddRef any interface we'll return. 
    if (NULL!=*ppv) 
        { 
        ((LPUNKNOWN)*ppv)->AddRef(); 
        return NOERROR; 
        } 
 
    return ResultFromScode(E_NOINTERFACE); 
    } 
 
 
STDMETHODIMP_(ULONG) CEnumFormatEtc::AddRef(void) 
    { 
    ++m_cRef; 
    return m_cRef; 
    } 
 
STDMETHODIMP_(ULONG) CEnumFormatEtc::Release(void) 
    { 
    if (0!=--m_cRef) 
        return m_cRef; 
 
    delete this; 
    return 0; 
    } 
 
 
 
 
 
 
 
/* 
 * CEnumFormatEtc::Next 
 * 
 * Purpose: 
 *  Returns the next element in the enumeration. 
 * 
 * Parameters: 
 *  cFE             ULONG number of FORMATETCs to return. 
 *  pFE             LPFORMATETC in which to store the returned 
 *                  structures. 
 *  pulFE           ULONG * in which to return how many we 
 *                  enumerated. 
 * 
 * Return Value: 
 *  HRESULT         NOERROR if successful, S_FALSE otherwise, 
 */ 
 
STDMETHODIMP CEnumFormatEtc::Next(ULONG cFE, LPFORMATETC pFE 
    , ULONG *pulFE) 
    { 
    ULONG               cReturn=0L; 
 
    if (NULL==m_prgfe) 
        return ResultFromScode(S_FALSE); 
 
    if (NULL==pulFE) 
        { 
        if (1L!=cFE) 
            return ResultFromScode(E_POINTER); 
        } 
    else 
        *pulFE=0L; 
 
    if (NULL==pFE || m_iCur >= m_cfe) 
        return ResultFromScode(S_FALSE); 
 
    while (m_iCur < m_cfe && cFE > 0) 
        { 
        *pFE++=m_prgfe[m_iCur++]; 
        cReturn++; 
        cFE--; 
        } 
 
    if (NULL!=pulFE) 
        *pulFE=cReturn; 
 
    return NOERROR; 
    } 
 
 
 
 
 
 
 
/* 
 * CEnumFormatEtc::Skip 
 * 
 * Purpose: 
 *  Skips the next n elements in the enumeration. 
 * 
 * Parameters: 
 *  cSkip           ULONG number of elements to skip. 
 * 
 * Return Value: 
 *  HRESULT         NOERROR if successful, S_FALSE if we could not 
 *                  skip the requested number. 
 */ 
 
STDMETHODIMP CEnumFormatEtc::Skip(ULONG cSkip) 
    { 
    if (((m_iCur+cSkip) >= m_cfe) || NULL==m_prgfe) 
        return ResultFromScode(S_FALSE); 
 
    m_iCur+=cSkip; 
    return NOERROR; 
    } 
 
 
 
 
 
 
/* 
 * CEnumFormatEtc::Reset 
 * 
 * Purpose: 
 *  Resets the current element index in the enumeration to zero. 
 * 
 * Parameters: 
 *  None 
 * 
 * Return Value: 
 *  HRESULT         NOERROR 
 */ 
 
STDMETHODIMP CEnumFormatEtc::Reset(void) 
    { 
    m_iCur=0; 
    return NOERROR; 
    } 
 
 
 
 
 
 
/* 
 * CEnumFormatEtc::Clone 
 * 
 * Purpose: 
 *  Returns another IEnumFORMATETC with the same state as ourselves. 
 * 
 * Parameters: 
 *  ppEnum          LPENUMFORMATETC * in which to return the 
 *                  new object. 
 * 
 * Return Value: 
 *  HRESULT         NOERROR or a general error value. 
 */ 
 
STDMETHODIMP CEnumFormatEtc::Clone(LPENUMFORMATETC *ppEnum) 
    { 
    PCEnumFormatEtc     pNew; 
 
    *ppEnum=NULL; 
 
    //Create the clone 
    pNew=new CEnumFormatEtc(m_cfe, m_prgfe); 
 
    if (NULL==pNew) 
        return ResultFromScode(E_OUTOFMEMORY); 
 
    pNew->AddRef(); 
    pNew->m_iCur=m_iCur; 
 
    *ppEnum=pNew; 
    return NOERROR; 
    }