对话框内画图

void TestView::OnPaint()
{
 CPaintDC dc(this); // device context for painting

 CWnd* pWnd = GetDlgItem(IDC_RADIOA);   //获取控件所以窗口句柄
 CDC* pControlDC = pWnd->GetDC();   //取设备句柄

 pWnd->Invalidate(TRUE);          //置窗口为无效状态
 pWnd->UpdateWindow();            //更新窗口
 pControlDC->SelectStockObject(BLACK_BRUSH);
 pControlDC->Rectangle(0, 0, 10, 10);
 pWnd->ReleaseDC(pControlDC);        //释放动态设备对象
}