VC绘制控件如何防止闪烁

void CXXXCtrl::OnPaint()
{
    CPaintDC dc(this);
    // TODO: 在此处添加消息处理程序代码
    CRect rect;
    CRect headerRect;
    CDC dcMem;    //内存DC
    CBitmap bmpMem;

    GetClientRect(&rect);
    dcMem.CreateCompatibleDC(&dc);
    bmpMem.CreateCompatibleBitmap(&dc, rect.Width(), rect.Height());
    dcMem.SelectObject(&bmpMem);
    dcMem.FillSolidRect(&rect, RGB(255,255,255));

    //这一句是调用默认的OnPaint()，把图形画在内存DC上
    DefWindowProc(WM_PAINT, (WPARAM)dcMem.m_hDC, (LPARAM)0);

    //输出
    dc.BitBlt(0,
        0,
        rect.Width(),
        rect.Height(),
        &dcMem,
        0,
        0,
        SRCCOPY);
    dcMem.DeleteDC();
    bmpMem.DeleteObject();
}