dataobj.cpp

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/*
 * DATAOBJ.CPP
 * Data Transfer Object Chapter 12
 *
 * Implementation of the CDataObject class.
 *
 * Copyright (c)1993-1995 Microsoft Corporation, All Rights Reserved
 *
 * Kraig Brockschmidt, Microsoft
 * Internet  :  [e-mail]
 * Compuserve:  >INTERNET:[e-mail]
 */


#include "dataobj.h"

extern HINSTANCE g_hInst;

/*
 * CDataObject::CDataObject
 * CDataObject::~CDataObject
 *
 * Parameters (Constructor):
 *  pUnkOuter       LPUNKNOWN of a controlling unknown.
 *  pfnDestroy      PFNDESTROYED to call when object is destroyed.
 */

CDataObject::CDataObject(LPUNKNOWN pUnkOuter
    , PFNDESTROYED pfnDestroy)
    {
    m_cRef=0;
    m_pUnkOuter=pUnkOuter;
    m_pfnDestroy=pfnDestroy;

    m_hList=NULL;
    m_pIDataObject=NULL;

    return;
    }


CDataObject::~CDataObject(void)
    {
    if (NULL!=m_pIDataObject)
        delete m_pIDataObject;

    Purge();

    if (NULL!=m_hList)
        DestroyWindow(m_hList);

    return;
    }



/*
 * CDataObject::Init
 *
 * Purpose:
 *  Performs any intiailization of a CDataObject that's prone to
 *  failure that we also use internally before exposing the object
 *  outside.
 *
 * Parameters:
 *  None
 *
 * Return Value:
 *  BOOL            TRUE if the function is successful,
 *                  FALSE otherwise.
 */

BOOL CDataObject::Init(void)
    {
    LPUNKNOWN       pIUnknown=this;

    if (NULL!=m_pUnkOuter)
        pIUnknown=m_pUnkOuter;

    //Allocate contained interfaces.
    m_pIDataObject=new CImpIDataObject(this, pIUnknown);

    if (NULL==m_pIDataObject)
        return FALSE;

    m_hList=CreateWindow(TEXT("listbox"), TEXT("renderings")
        , WS_POPUP | LBS_OWNERDRAWFIXED, 0, 0, 100, 100
        , HWND_DESKTOP, NULL, g_hInst, NULL);

    if (NULL==m_hList)
        return FALSE;

    return TRUE;
    }



/*
 * CDataObject::Purge
 *
 * Purpose:
 *  Cleans out all entries in our listbox.
 *
 * Parameters:
 *  None
 *
 * Return Value:
 *  None
 */

void CDataObject::Purge(void)
    {
    UINT        i, cItems;
    PRENDERING  pRen;
    DWORD       cb;

    if (NULL==m_hList)
        return;

    cItems=(UINT)SendMessage(m_hList, LB_GETCOUNT, 0, 0L);

    for (i=0; i < cItems; i++)
        {
        cb=SendMessage(m_hList, LB_GETTEXT, i, (LPARAM)&pRen);

        if (LB_ERR!=cb)
            {
            /*
             * Release the data completely being sure to reinstate
             * the original pUnkForRelease.
             */
            pRen->stm.pUnkForRelease=pRen->pUnkOrg;
            ReleaseStgMedium(&pRen->stm);
            delete pRen;
            }
        }

    SendMessage(m_hList, LB_RESETCONTENT, 0, 0L);
    return;
    }






/*
 * CDataObject::QueryInterface
 * CDataObject::AddRef
 * CDataObject::Release
 *
 * Purpose:
 *  IUnknown members for CDataObject object.
 */

STDMETHODIMP CDataObject::QueryInterface(REFIID riid, PPVOID ppv)
    {
    *ppv=NULL;

    if (IID_IUnknown==riid)
        *ppv=this;

    if (IID_IDataObject==riid)
        *ppv=m_pIDataObject;

    if (NULL!=*ppv)
        {
        ((LPUNKNOWN)*ppv)->AddRef();
        return NOERROR;
        }

    return ResultFromScode(E_NOINTERFACE);
    }


STDMETHODIMP_(ULONG) CDataObject::AddRef(void)
    {
    return ++m_cRef;
    }


STDMETHODIMP_(ULONG) CDataObject::Release(void)
    {
    if (0!=--m_cRef)
        return m_cRef;

    if (NULL!=m_pfnDestroy)
        (*m_pfnDestroy)();

    delete this;
    return 0;
    }