vs2010 单文档MFC 通过加载位图文件作为客户区背景

BOOL CdddView::OnEraseBkgnd(CDC* pDC)
{
    // TODO: 在此添加消息处理程序代码和/或调用默认值


    CString string("b.bmp"); 
    HBITMAP hbitmap=(HBITMAP)::LoadImage(AfxGetInstanceHandle(),string, 
        IMAGE_BITMAP,1024,768, LR_CREATEDIBSECTION|LR_LOADFROMFILE); 
    //VERY IMPORTANT:NOT CALL THE SUPER CLASS FUNCTION 
    CPaintDC dc(this); 
    if(hbitmap==NULL) 
        return FALSE; 
    CBitmap bitmap; 
    bitmap.Attach(hbitmap); 
    BITMAP bmp; 
    bitmap.GetBitmap(&bmp); 
    CDC memDc;

    memDc.CreateCompatibleDC(pDC);
    CBitmap* pOldBitmap = memDc.SelectObject(&bitmap);
    CRect rect;
    GetClientRect(&rect);
    pDC->SetStretchBltMode(COLORONCOLOR);//这个模式不设置的话会导致图片严重失真
    pDC->StretchBlt(0,0,rect.Width() ,rect.Height(),
        &memDc,0,0,bmp.bmWidth,bmp.bmHeight,SRCCOPY);
    memDc.SelectObject(pOldBitmap);
    memDc.DeleteDC();                                      //删除DC
    return TRUE; 
}

BOOL CMainFrame::PreCreateWindow(CREATESTRUCT& cs)
{
    if( !CFrameWndEx::PreCreateWindow(cs) )
        return FALSE;
    // TODO: 在此处通过修改
    //  CREATESTRUCT cs 来修改窗口类或样式
    cs.style &=~FWS_ADDTOTITLE;

    cs.lpszName = _T("XXX系统");

    return TRUE;
}