// Constructor for a curve object 
CCurve::CCurve( const CPoint& FirstPoint, const CPoint& SecondPoint,
                const COLORREF& Color )
{
    m_PointList.AddTail( FirstPoint );  // Add the 1st point to the list
    m_PointList.AddTail( SecondPoint ); // Add the second point to the list
    m_Color = Color;      // Set Circle color
    m_Pen = 1;            // Set pen width

    // Construct the enclosing rectangle assumming MM_TEXT mode
    m_EnclosingRect = CRect( FirstPoint, SecondPoint );
    m_EnclosingRect.NormalizeRect();
}

void CCurve::AddSegment( const CPoint& Point )
{
    m_PointList.AddTail( Point );  // Add the point to the end

    // Modify the enclosing rectangle for the new point
    m_EnclosingRect = CRect( min(Point.x, m_EnclosingRect.left),
                             min(Point.y, m_EnclosingRect.top),
                             max(Point.x, m_EnclosingRect.right),
                             max(Point.y, m_EnclosingRect.bottom) );
}

// Draw a curve
void CCurve::Draw( CDC* pDC ) const
{
    // Create a pen for this object and
    // initialize it to the object color and line width
    CPen aPen;

    if (!aPen.CreatePen(PS_SOLID, m_Pen, m_Color ))
    {
       // Pen creation failed, Abort the program
       AfxMessageBox("Pen creation failed drawing a line", MB_OK );
       AfxAbort();
    }

    CPen* pOldPen = pDC->SelectObject( &aPen );

    // Now draw the curve
    // Get the position in the list of the first element
    POSITION aPosition = m_PointList.GetHeadPosition();

    // As long as it's good, move to that point
    if ( aPosition )
       pDC->MoveTo( m_PointList.GetNext(aPosition) );

    // Draw a segment for each of the following points
    while (aPosition )
       pDC->LineTo( m_PointList.GetNext(aPosition) );

    pDC->SelectObject( pOldPen ); // Restore the old pen
}