MFC 对话框背景图片每隔一秒显示一张，图片格式一定要是PNG,JPG格式，其他的不用

#ifndef HIMETRIC_INCH
#define HIMETRIC_INCH 2540
#endif
  CString picfullname = "test.jpg";
  CDC* pDC = GetDC();
  IPicture* pPic;
  IStream* pStm;     
  
  CFileStatus fstatus;     //CFileStatus文件属性类
  CFile file;
  LONG cb;
  
  //打开文件并获得文件的真实大小
  if(file.Open(picfullname, CFile::modeRead)
   &&file.GetStatus(picfullname, fstatus)
   &&(-1 != (cb = fstatus.m_size)))
  {
   //从堆中分配指定数量字节的一整块，这时系统无法提供零零碎碎的局部或全局的堆   
   HGLOBAL hGlobal = GlobalAlloc(GMEM_MOVEABLE, cb);     
   LPVOID pvData = NULL;
   if(NULL != hGlobal)
   {
    //锁定全局内存对象并返回它的首地址
    if(NULL != (pvData = GlobalLock(hGlobal)))     
    {
     //把文件内容读进全局内存对象的地址空间中
     file.ReadHuge(pvData, cb);
     //GlobalUnlock函数把以GMEM_MOVEABLE方式分配的内存对象的锁定计数器减1
     GlobalUnlock(hGlobal);
     //从全局内存中创建stream对象，第二个参数指定当stream释放时是否自动释放全局内存
     CreateStreamOnHGlobal(hGlobal, TRUE, &pStm);
     //创建一个新的picture对象并用stream对象中的内容初始化   
     if(SUCCEEDED(OleLoadPicture(pStm, fstatus.m_size, TRUE, IID_IPicture, (LPVOID*)&pPic)))
     {
      OLE_XSIZE_HIMETRIC hmWidth;
      OLE_YSIZE_HIMETRIC hmHeight;
      //得到picture对象中图片的宽和高
      pPic->get_Width(&hmWidth);
      pPic->get_Height(&hmHeight);
      
      int nWidth = MulDiv(hmWidth, pDC->GetDeviceCaps(LOGPIXELSX), HIMETRIC_INCH);
      int nHeight = MulDiv(hmHeight, pDC->GetDeviceCaps(LOGPIXELSY), HIMETRIC_INCH);
      pStm->Release();
      pStm = NULL;
      //把图像显示在dc中
      CRect rect;
      GetClientRect(&rect);
      //if(FAILED(pPic->Render(*pDC, 0, 0, (DWORD)nWidth, (DWORD)nHeight, 0, hmHeight, hmWidth, -hmHeight, NULL)))
      if(FAILED(pPic->Render(*pDC, 0, 0, rect.Width(), rect.Height(), 0, hmHeight, hmWidth, -hmHeight, NULL)))
      {
       MessageBox("图片出错!", "提示", MB_ICONINFORMATION);
      }
      pDC->SetBkMode(TRANSPARENT);
      //释放不要的picture对象，并把指针清空
      pPic->Release();
      pPic = NULL;
      //释放不要的全局内存对象，这个千万别忘了(32位程序不需要这行，系统会自动释放；16位程序一定要)
      FreeResource(hGlobal);
     }
     else
     {
      MessageBox("图片出错!", "提示", MB_ICONINFORMATION);
     }
    }
   }
  }
  else
  {
   MessageBox("图片出错!", "提示", MB_ICONINFORMATION);
 }