示例三、在窗口中显示一幅 JPG 图象。
void CxxxView::OnDraw(CDC* pDC)
{
::CoInitialize(NULL); // COM 初始化
HRESULT hr;
CFile file;
file.Open( "c:\\aa.jpg", CFile::modeRead | CFile::shareDenyNone ); // 读入文件内容
DWORD dwSize = file.GetLength();
HGLOBAL hMem = ::GlobalAlloc( GMEM_MOVEABLE, dwSize );
LPVOID lpBuf = ::GlobalLock( hMem );
file.ReadHuge( lpBuf, dwSize );
file.Close();
::GlobalUnlock( hMem );
IStream * pStream = NULL;
IPicture * pPicture = NULL;
// 由 HGLOBAL 得到 IStream，参数 TRUE 表示释放 IStream 的同时，释放内存
hr = ::CreateStreamOnHGlobal( hMem, TRUE, &pStream );
ASSERT ( SUCCEEDED(hr) );
hr = ::OleLoadPicture( pStream, dwSize, TRUE, IID_IPicture, ( LPVOID * )&pPicture );
ASSERT(hr==S_OK);
long nWidth,nHeight; // 宽高，MM_HIMETRIC 模式，单位是0.01毫米
pPicture->get_Width( &nWidth ); // 宽
pPicture->get_Height( &nHeight ); // 高
////////原大显示//////
CSize sz( nWidth, nHeight );
pDC->HIMETRICtoDP( &sz ); // 转换 MM_HIMETRIC 模式单位为 MM_TEXT 像素单位
pPicture->Render(pDC->m_hDC,0,0,sz.cx,sz.cy,
0,nHeight,nWidth,-nHeight,NULL);
////////按窗口尺寸显示////////
// CRect rect; GetClientRect(&rect);
// pPicture->Render(pDC->m_hDC,0,0,rect.Width(),rect.Height(),
// 0,nHeight,nWidth,-nHeight,NULL);
if ( pPicture ) pPicture->Release();// 释放 IPicture 指针
if ( pStream ) pStream->Release(); // 释放 IStream 指针，同时释放了 hMem
::CoUninitialize();
}
