mapnik/deps/agg/src/agg_vcgen_bspline.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 "agg_vcgen_bspline.h"

namespace agg
{

//------------------------------------------------------------------------
vcgen_bspline::vcgen_bspline() :
    m_src_vertices(),
    m_spline_x(),
    m_spline_y(),
    m_interpolation_step(1.0/50.0),
    m_closed(0),
    m_status(initial),
    m_src_vertex(0)
{
}


//------------------------------------------------------------------------
void vcgen_bspline::remove_all()
{
    m_src_vertices.remove_all();
    m_closed = 0;
    m_status = initial;
    m_src_vertex = 0;
}


//------------------------------------------------------------------------
void vcgen_bspline::add_vertex(double x, double y, unsigned cmd)
{
    m_status = initial;
    if(is_move_to(cmd))
    {
        m_src_vertices.modify_last(point_d(x, y));
    }
    else
    {
        if(is_vertex(cmd))
        {
            m_src_vertices.add(point_d(x, y));
        }
        else
        {
            m_closed = get_close_flag(cmd);
        }
    }
}


//------------------------------------------------------------------------
void vcgen_bspline::rewind(unsigned)
{
    m_cur_abscissa = 0.0;
    m_max_abscissa = 0.0;
    m_src_vertex = 0;
    if(m_status == initial && m_src_vertices.size() > 2)
    {
        if(m_closed)
        {
            m_spline_x.init(m_src_vertices.size() + 8);
            m_spline_y.init(m_src_vertices.size() + 8);
            m_spline_x.add_point(0.0, m_src_vertices.prev(m_src_vertices.size() - 3).x);
            m_spline_y.add_point(0.0, m_src_vertices.prev(m_src_vertices.size() - 3).y);
            m_spline_x.add_point(1.0, m_src_vertices[m_src_vertices.size() - 3].x);
            m_spline_y.add_point(1.0, m_src_vertices[m_src_vertices.size() - 3].y);
            m_spline_x.add_point(2.0, m_src_vertices[m_src_vertices.size() - 2].x);
            m_spline_y.add_point(2.0, m_src_vertices[m_src_vertices.size() - 2].y);
            m_spline_x.add_point(3.0, m_src_vertices[m_src_vertices.size() - 1].x);
            m_spline_y.add_point(3.0, m_src_vertices[m_src_vertices.size() - 1].y);
        }
        else
        {
            m_spline_x.init(m_src_vertices.size());
            m_spline_y.init(m_src_vertices.size());
        }
        unsigned i;
        for(i = 0; i < m_src_vertices.size(); i++)
        {
            double x = m_closed ? i + 4 : i;
            m_spline_x.add_point(x, m_src_vertices[i].x);
            m_spline_y.add_point(x, m_src_vertices[i].y);
        }
        m_cur_abscissa = 0.0;
        m_max_abscissa = m_src_vertices.size() - 1;
        if(m_closed)
        {
            m_cur_abscissa = 4.0;
            m_max_abscissa += 5.0;
            m_spline_x.add_point(m_src_vertices.size() + 4, m_src_vertices[0].x);
            m_spline_y.add_point(m_src_vertices.size() + 4, m_src_vertices[0].y);
            m_spline_x.add_point(m_src_vertices.size() + 5, m_src_vertices[1].x);
            m_spline_y.add_point(m_src_vertices.size() + 5, m_src_vertices[1].y);
            m_spline_x.add_point(m_src_vertices.size() + 6, m_src_vertices[2].x);
            m_spline_y.add_point(m_src_vertices.size() + 6, m_src_vertices[2].y);
            m_spline_x.add_point(m_src_vertices.size() + 7, m_src_vertices.next(2).x);
            m_spline_y.add_point(m_src_vertices.size() + 7, m_src_vertices.next(2).y);
        }
        m_spline_x.prepare();
        m_spline_y.prepare();
    }
    m_status = ready;
}






//------------------------------------------------------------------------
unsigned vcgen_bspline::vertex(double* x, double* y)
{
    unsigned cmd = path_cmd_line_to;
    while(!is_stop(cmd))
    {
        switch(m_status)
        {
        case initial:
            rewind(0);

        case ready:
            if(m_src_vertices.size() < 2)
            {
                cmd = path_cmd_stop;
                break;
            }

            if(m_src_vertices.size() == 2)
            {
                *x = m_src_vertices[m_src_vertex].x;
                *y = m_src_vertices[m_src_vertex].y;
                m_src_vertex++;
                if(m_src_vertex == 1) return path_cmd_move_to;
                if(m_src_vertex == 2) return path_cmd_line_to;
                cmd = path_cmd_stop;
                break;
            }

            cmd = path_cmd_move_to;
            m_status = polygon;
            m_src_vertex = 0;

        case polygon:
            if(m_cur_abscissa >= m_max_abscissa)
            {
                if(m_closed)
                {
                    m_status = end_poly;
                    break;
                }
                else
                {
                    *x = m_src_vertices[m_src_vertices.size() - 1].x;
                    *y = m_src_vertices[m_src_vertices.size() - 1].y;
                    m_status = end_poly;
                    return path_cmd_line_to;
                }
            }

            *x = m_spline_x.get_stateful(m_cur_abscissa);
            *y = m_spline_y.get_stateful(m_cur_abscissa);
            m_src_vertex++;
            m_cur_abscissa += m_interpolation_step;
            return (m_src_vertex == 1) ? path_cmd_move_to : path_cmd_line_to;

        case end_poly:
            m_status = stop;
            return path_cmd_end_poly | m_closed;

        case stop:
            return path_cmd_stop;
        }
    }
    return cmd;
}


}