用IPicture时遇到的问题

opera321 2008-04-10 05:39:49

用过IPicture的朋友都知道可以利用下面的方法显示jpg图片，假如我定义一个全局的IPicture *pGlobalPic=NULL;
在调用下面的PicChangeImmediate()的时候，将pGlobalPic作为参数。为什么在该函数执行完成后，用pGlobalPic无法显示图片。
即

if(FAILED(pPic->Render(*pDC,0,0,(DWORD)cx,(DWORD)cy,0,cySrc,cxSrc,-cySrc,NULL)))     

						AfxMessageBox("Failed   To   Render   The   picture!");     

					pPic->Release();

不起作用，但也不报错。很纳闷！哪位仁兄给指点一下，多谢!



void CDispPicView::PicChangeImmediate(CString &str,IPicture *pPic)

{

	CClientDC *pDC=new CClientDC(this);

	IStream *pStm;

	CFileStatus status;

	LONG cb;

	CFile file;

	if(file.Open(str,CFile::modeRead) && file.GetStatus(str,status)&&((cb=status.m_size)!=-1))     

	{     

		HGLOBAL hGlobal=GlobalAlloc(GMEM_MOVEABLE,cb);     

		LPVOID  pvData=NULL;     

		if(hGlobal!=NULL)     

		{     

			if((pvData=GlobalLock(hGlobal))!=NULL)     

			{     

				file.ReadHuge(pvData,cb);     

				GlobalUnlock(hGlobal);     

				CreateStreamOnHGlobal(hGlobal,TRUE,&pStm);     

				

				if(SUCCEEDED(OleLoadPicture(pStm,status.m_size,TRUE,IID_IPicture,(LPVOID*)&pPic)))     

				{     		

					pPic->get_Width(&cxSrc);     

					pPic->get_Height(&cySrc);     

					

					cx= (double)pDC->GetDeviceCaps(HORZRES)*(double)cxSrc/((double)pDC->GetDeviceCaps(HORZSIZE)*100.0);     

					cy= (double)pDC->GetDeviceCaps(VERTRES)*(double)cySrc/((double)pDC->GetDeviceCaps(VERTSIZE)*100.0);

					

					if(FAILED(pPic->Render(*pDC,0,0,(DWORD)cx,(DWORD)cy,0,cySrc,cxSrc,-cySrc,NULL)))     

						AfxMessageBox("Failed   To   Render   The   picture!");     

					pPic->Release();     

				}     

				else     

					AfxMessageBox("Error   Loading   Picture   From   Stream!");     

			}     

		}     

	}     

	else     

		AfxMessageBox("Can't   Open   Image   File!");

	if(pDC)

	{

		pDC->DeleteDC();

	}

	

}