[code]  CPaintDC   dc(this);   
          CRect   rect;   
          GetClientRect(&rect);   
          CDC   dcMem;   
          dcMem.CreateCompatibleDC(&dc);   
          CBitmap   bmpBackground;   
          bmpBackground.LoadBitmap(IDB_BITMAP2);   
                 
          BITMAP   bitmap;   
          bmpBackground.GetBitmap(&bitmap);   
          CBitmap   *pbmpOld=dcMem.SelectObject(&bmpBackground);   
          dc.StretchBlt(0,0,rect.Width(),rect.Height(),&dcMem,0,0,   
         bitmap.bmWidth,bitmap.bmHeight,SRCCOPY);
[/code]
这是我在ONPAINT里写的我在OnMouseMove里又写个这段代码 
我想实现效果是当鼠标移动到某个位置时切换背景图
麻烦看下怎么实现