MFC控件第一讲.DC编程

void CCDCDlg::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
    {
        CDialogEx::OnPaint();
    }
}

    HDC hdc = ::GetDC(m_hWnd);              //用于绘制的DC
    PAINTSTRUCT ps;       //保存DC的信息结构体
    ::BeginPaint(m_hWnd, &ps);

    ::DrawText(hdc, TEXT("Hello"), wcslen(TEXT("Hello")), CRect(200, 200, 200, 200), DT_SINGLELINE);//单行显示

    ::EndPaint(m_hWnd, &ps);

void CCDCDlg::OnBnClickedButton1()
{
    CClientDC dc(this);
    dc.Ellipse(0, 0, 100, 100); 画个圆
}