mapnik/deps/agg/src/agg_vcgen_contour.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
//----------------------------------------------------------------------------
//
// Contour generator
//
//----------------------------------------------------------------------------

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

namespace agg
{

//------------------------------------------------------------------------
vcgen_contour::vcgen_contour() :
    m_stroker(),
    m_width(1),
    m_src_vertices(),
    m_out_vertices(),
    m_status(initial),
    m_src_vertex(0),
    m_closed(0),
    m_orientation(0),
    m_auto_detect(false)
{
}

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

//------------------------------------------------------------------------
void vcgen_contour::add_vertex(double x, double y, unsigned cmd)
{
    m_status = initial;
    if(is_move_to(cmd))
    {
        m_src_vertices.modify_last(vertex_dist(x, y));
    }
    else
    {
        if(is_vertex(cmd))
        {
            m_src_vertices.add(vertex_dist(x, y));
        }
        else
        {
            if(is_end_poly(cmd))
            {
                m_closed = get_close_flag(cmd);
                if(m_orientation == path_flags_none)
                {
                    m_orientation = get_orientation(cmd);
                }
            }
        }
    }
}

//------------------------------------------------------------------------
void vcgen_contour::rewind(unsigned)
{
    if(m_status == initial)
    {
        m_src_vertices.close(true);
        if(m_auto_detect)
        {
            if(!is_oriented(m_orientation))
            {
                m_orientation = (calc_polygon_area(m_src_vertices) > 0.0) ?
                    path_flags_ccw :
                    path_flags_cw;
            }
        }
        if(is_oriented(m_orientation))
        {
            m_stroker.width(is_ccw(m_orientation) ? m_width : -m_width);
        }
    }
    m_status = ready;
    m_src_vertex = 0;
}

//------------------------------------------------------------------------
unsigned vcgen_contour::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 + unsigned(m_closed != 0))
            {
                cmd = path_cmd_stop;
                break;
            }
            m_status = outline;
            cmd = path_cmd_move_to;
            m_src_vertex = 0;
            m_out_vertex = 0;

        case outline:
            if(m_src_vertex >= m_src_vertices.size())
            {
                m_status = end_poly;
                break;
            }
            m_stroker.calc_join(m_out_vertices,
                                m_src_vertices.prev(m_src_vertex),
                                m_src_vertices.curr(m_src_vertex),
                                m_src_vertices.next(m_src_vertex),
                                m_src_vertices.prev(m_src_vertex).dist,
                                m_src_vertices.curr(m_src_vertex).dist);
            ++m_src_vertex;
            m_status = out_vertices;
            m_out_vertex = 0;

        case out_vertices:
            if(m_out_vertex >= m_out_vertices.size())
            {
                m_status = outline;
            }
            else
            {
                const point_d& c = m_out_vertices[m_out_vertex++];
                *x = c.x;
                *y = c.y;
                return cmd;
            }
            break;

        case end_poly:
            if(!m_closed) return path_cmd_stop;
            m_status = stop;
            return path_cmd_end_poly | path_flags_close | path_flags_ccw;

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

}