请教：MFC中Onpaint函数造成内存增加的原因？

void CInterFaceDlg::OnPaint()
{
    CPaintDC dc(this); // device context for painting
    // TODO: 在此处添加消息处理程序代码
    CDC* pDC = &dc;                                  //获取设备句柄
    HDC hDc=pDC->m_hDC;

   
   
    CRect rect;
    GetClientRect(&rect);

    CDC dcMem;
    CBitmap m_pBitmap;

    dcMem.CreateCompatibleDC(&dc);

    m_pBitmap.CreateCompatibleBitmap(pDC,rect.Width(),rect.Height());
   
    dcMem.SelectObject(&m_pBitmap);
   
    dcMem.FillSolidRect(rect,RGB(255,255,255));



    CBrush brushBlue3(RGB(0,0,0));
    dcMem.SelectObject(&brushBlue3);


    Rectangle(dcMem.m_hDC,160,203,160+PosProg,213);
   
        
    pDC->BitBlt(0,0,rect.Width(),rect.Height(),&dcMem,0,0,SRCCOPY);
   
     
    dcMem.DeleteDC();
    m_pBitmap.DeleteObject();
    // 不为绘图消息调用 CDialog::OnPaint()
}