急！急！急！用vc如何把数据库中的jpeg文件读出并在视图中显示出来?

Question

1。jpeg在数据库中是否以二进制方式存储？
2。若是以二进制方式存储，读出时怎样在视图上显示？
   我知道一种读数据库中位图的方法，读出来后显示是用CreateDIBitmap函数得到HBITMAP.但是显示jpeg又怎样做呢？？   还望哪位大虾指点，不甚感激！！

Answer 1

1.是
2。void CShowJpgView::OnDraw(CDC* pDC)
{
CShowJpgDoc* pDoc = GetDocument();
ASSERT_VALID(pDoc);
if(m_ok==false)
{
IStream *pStm; 
CFileStatus fstatus; 
CFile file; 
LONG cb; 
if (file.Open("test.jpg",CFile::modeRead)&&file.GetStatus("test.jpg",fstatus)&& 
((cb = fstatus.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,fstatus.m_size,TRUE,IID_IPicture,(LPVOID*)&pPic))) 
{ 
OLE_XSIZE_HIMETRIC hmWidth; 
OLE_YSIZE_HIMETRIC hmHeight;  pPic->get_Width(&hmWidth); 
pPic->get_Height(&hmHeight); // double fX,fY; 
// fX = (double)pDC->GetDeviceCaps(HORZRES)*(double)hmWidth/((double)pDC->GetDeviceCaps(HORZSIZE)*100.0); 
// fY = (double)pDC->GetDeviceCaps(VERTRES)*(double)hmHeight/((double)pDC->GetDeviceCaps(VERTSIZE)*100.0); 
// if(FAILED(pPic->Render(*pDC,0,0,(DWORD)fX,(DWORD)fY,0,hmHeight,hmWidth,-hmHeight,NULL))) 
double fX,fY; 
fX = 640;
fY = 480;
if(FAILED(pPic->Render(*pDC,0,0,(DWORD)fX,(DWORD)fY,0,hmHeight,hmWidth,-hmHeight,NULL))) 
AfxMessageBox("Failed To Render The picture!"); 
// pPic->Release(); 
m_ok=true;
} 
else 
AfxMessageBox("Error Loading Picture From Stream!"); 
} 
} 
} 
else 
AfxMessageBox("Can't Open Image File!"); 
}
else
{
OLE_XSIZE_HIMETRIC hmWidth; 
OLE_YSIZE_HIMETRIC hmHeight; 
pPic->get_Width(&hmWidth); 
pPic->get_Height(&hmHeight); 
double fX,fY; 
fX = 640;
fY = 480;
pPic->Render(*pDC,0,0,(DWORD)fX,(DWORD)fY,0,hmHeight,hmWidth,-hmHeight,NULL);
}
// TODO: add draw code for native data here
}