1.插入一个Bitmap的资源图片，如果资源名称为：IDC_BITMAP1

2.在CXXXDialog::OnPaint()中实现：

void CMyDialogDlg::OnPaint()
{
    if (IsIconic())
    {
        CPaintDC dc(this); // 用于绘制的设备上下文

        SendMessage(WM_ICONERASEBKGND, reinterpret_cast<WPARAM>(dc.GetSafeHdc()), 0);

        // 使图标在工作区矩形中居中
        int cxIcon = GetSystemMetrics(SM_CXICON);
        int cyIcon = GetSystemMetrics(SM_CYICON);
        CRect rect;
        GetClientRect(&rect);
        int x = (rect.Width() - cxIcon + 1) / 2;
        int y = (rect.Height() - cyIcon + 1) / 2;

        // 绘制图标
        dc.DrawIcon(x, y, m_hIcon);
    }
    else
    {
        //
        // 给窗口加入?背景
        //
        CPaintDC dc(this);
        CRect rc;
        GetClientRect(&rc);
        CDC dcMem;
        dcMem.CreateCompatibleDC(&dc);
        CBitmap bmpBackground;
        bmpBackground.LoadBitmap(IDB_BITMAP1);

        BITMAP bitmap;
        bmpBackground.GetBitmap(&bitmap);
        CBitmap* pbmpPri = dcMem.SelectObject(&bmpBackground);
        dc.StretchBlt(0,0,rc.Width(), rc.Height(), &dcMem,0,0,bitmap.bmWidth, bitmap.bmHeight, SRCCOPY);
    }
}