在MFC的CDialog类中可以显示JPG图片 在CFromview类中用同样的方法显示不了

Question

HGLOBAL hMem;
IStream *m_pStream;
IPicture *m_pPicture;
OLE_XSIZE_HIMETRIC m_JPGWidth;
OLE_XSIZE_HIMETRIC m_JPGHeight;

CRect rect(100,120,600,460);
CString path;
CFile file;
CFileDialog dlg(TRUE,_T("jpg"),_T("*.jpg"), OFN_HIDEREADONLY|OFN_OVERWRITEPROMPT,   
    _T("JPEG文件(*.jpg)|*.jpg|GIF文件(*.gif)|*.gif|bmp文件(*.bmp)|*.bmp|所有文件(*.*)|*.*|"),NULL);   
if(dlg.DoModal()==IDOK)   
{   
    path=dlg.GetPathName(); 
}  

file.Open(path,CFile::modeReadWrite);
DWORD len=file.GetLength();
hMem= GlobalAlloc(GMEM_MOVEABLE,len);
LPVOID pData=NULL;
pData=GlobalLock(hMem);
file.Read(pData,len);
file.Close();
GlobalUnlock(hMem);
CreateStreamOnHGlobal(hMem,TRUE,&m_pStream);
OleLoadPicture(m_pStream,len,TRUE,IID_IPicture,(LPVOID*)&m_pPicture);
m_pPicture->get_Height(&m_JPGHeight);
m_pPicture->get_Width(&m_JPGWidth);
CDC *pDC=NULL;  
pDC=this->GetDC();
m_pPicture->Render(pDC->m_hDC,0,0,(int)rect.Width(),(int)rect.Height(),0,m_JPGHeight,m_JPGWidth,-m_JPGHeight,NULL);

Answer 1

CFromview会引发重绘，打开文件得到文件名存在一个变量，在OnDraw里绘图。