draw simple rectangle in MFC Dialog-Based

I wrote this code to draw a simple rectangle in a dialog , I also added ON_WM_PAINT() to my message map. but it didnt show anything on dialog to me ! I really appreciate it if anyone could tell my mistakes in code:

void Ctest4Dlg::OnPaint()
{
    if (IsIconic())
    {
        CPaintDC开发者_开发知识库 dc(this); // device context for painting
        // TODO: Add your message handler code here

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

        // Center icon in client rectangle
        int cxIcon = GetSystemMetrics(SM_CXICON);
        int cyIcon = GetSystemMetrics(SM_CYICON);
        CRect rect;
        GetClientRect(&rect);
        int x = 2;
        int y = 2;

        // Draw the icon
        dc.DrawIcon(x, y, m_hIcon);

        //I want to draw a rectangle 
        dc.Rectangle(10,10,50,50);
    }
    else
    {
        CDialogEx::OnPaint();
    }
}

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Looks like your paint code only runs when the window is iconic? Why are you doing that?

Put it in the else block, after the call to CDialogEx::OnPaint().

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Your first and biggest mistake is trying to draw directly in a dialog. While it is possible to do so, it's almost always a bad idea. A dialog should usually be treated as a container for controls.