//设置对话框背景图
  PAINTSTRUCT ps;
  CDC *dc = BeginPaint(&ps);
  CDC memdc;
  CRect rect;
  CBitmap bitmap;
  BITMAP szbitmap;
  bitmap.LoadBitmap( IDB_QAM_MAIN );
  bitmap.GetObject( sizeof(BITMAP),&szbitmap );
  CSize size( szbitmap.bmWidth,szbitmap.bmHeight );
  memdc.CreateCompatibleDC(dc);
  CBitmap *oldbitmap=memdc.SelectObject(&bitmap);
  GetClientRect(&rect);
  dc->StretchBlt(0,0,rect.Width(),rect.Height(),
   &memdc,0,0,size.cx,size.cy,SRCCOPY);
  memdc.SelectObject(oldbitmap);
  memdc.DeleteDC();
  EndPaint(&ps);
from: 
http://www.360doc.com/showWeb/0/18/157828.aspx