mapnik/deps/agg/src/agg_trans_warp_magnifier.cpp

//----------------------------------------------------------------------------
// Anti-Grain Geometry - Version 2.4
// Copyright (C) 2002-2005 Maxim Shemanarev (http://www.antigrain.com)
//
// Permission to copy, use, modify, sell and distribute this software
// is granted provided this copyright notice appears in all copies.
// This software is provided "as is" without express or implied
// warranty, and with no claim as to its suitability for any purpose.
//
//----------------------------------------------------------------------------
// Contact: mcseem@antigrain.com
//          mcseemagg@yahoo.com
//          http://www.antigrain.com
//----------------------------------------------------------------------------

#include <math.h>
#include "agg_trans_warp_magnifier.h"

namespace agg
{

//------------------------------------------------------------------------
void trans_warp_magnifier::transform(double* x, double* y) const
{
    double dx = *x - m_xc;
    double dy = *y - m_yc;
    double r = sqrt(dx * dx + dy * dy);
    if(r < m_radius)
    {
        *x = m_xc + dx * m_magn;
        *y = m_yc + dy * m_magn;
        return;
    }

    double m = (r + m_radius * (m_magn - 1.0)) / r;
    *x = m_xc + dx * m;
    *y = m_yc + dy * m;
}

//------------------------------------------------------------------------
void trans_warp_magnifier::inverse_transform(double* x, double* y) const
{
    // New version by Andrew Skalkin
    //-----------------
    double dx = *x - m_xc;
    double dy = *y - m_yc;
    double r = sqrt(dx * dx + dy * dy);

    if(r < m_radius * m_magn)
    {
        *x = m_xc + dx / m_magn;
        *y = m_yc + dy / m_magn;
    }
    else
    {
        double rnew = r - m_radius * (m_magn - 1.0);
        *x = m_xc + rnew * dx / r;
        *y = m_yc + rnew * dy / r;
    }

    // Old version
    //-----------------
    //trans_warp_magnifier t(*this);
    //t.magnification(1.0 / m_magn);
    //t.radius(m_radius * m_magn);
    //t.transform(x, y);
}


}