mapnik/deps/agg/src/agg_vcgen_stroke.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
//----------------------------------------------------------------------------
//
// Stroke generator
//
//----------------------------------------------------------------------------
#include <math.h>
#include "agg_vcgen_stroke.h"
#include "agg_shorten_path.h"

namespace agg
{

//------------------------------------------------------------------------
vcgen_stroke::vcgen_stroke() :
    m_stroker(),
    m_src_vertices(),
    m_out_vertices(),
    m_shorten(0.0),
    m_closed(0),
    m_status(initial),
    m_src_vertex(0),
    m_out_vertex(0)
{
}

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


//------------------------------------------------------------------------
void vcgen_stroke::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
        {
            m_closed = get_close_flag(cmd);
        }
    }
}

//------------------------------------------------------------------------
void vcgen_stroke::rewind(unsigned)
{
    if(m_status == initial)
    {
        m_src_vertices.close(m_closed != 0);
        shorten_path(m_src_vertices, m_shorten, m_closed);
        if(m_src_vertices.size() < 3) m_closed = 0;
    }
    m_status = ready;
    m_src_vertex = 0;
    m_out_vertex = 0;
}


//------------------------------------------------------------------------
unsigned vcgen_stroke::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 = m_closed ? outline1 : cap1;
            cmd = path_cmd_move_to;
            m_src_vertex = 0;
            m_out_vertex = 0;
            break;

        case cap1:
            m_stroker.calc_cap(m_out_vertices,
                               m_src_vertices[0],
                               m_src_vertices[1],
                               m_src_vertices[0].dist);
            m_src_vertex = 1;
            m_prev_status = outline1;
            m_status = out_vertices;
            m_out_vertex = 0;
            break;

        case cap2:
            m_stroker.calc_cap(m_out_vertices,
                               m_src_vertices[m_src_vertices.size() - 1],
                               m_src_vertices[m_src_vertices.size() - 2],
                               m_src_vertices[m_src_vertices.size() - 2].dist);
            m_prev_status = outline2;
            m_status = out_vertices;
            m_out_vertex = 0;
            break;

        case outline1:
            if(m_closed)
            {
                if(m_src_vertex >= m_src_vertices.size())
                {
                    m_prev_status = close_first;
                    m_status = end_poly1;
                    break;
                }
            }
            else
            {
                if(m_src_vertex >= m_src_vertices.size() - 1)
                {
                    m_status = cap2;
                    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_prev_status = m_status;
            m_status = out_vertices;
            m_out_vertex = 0;
            break;

        case close_first:
            m_status = outline2;
            cmd = path_cmd_move_to;

        case outline2:
            if(m_src_vertex <= unsigned(m_closed == 0))
            {
                m_status = end_poly2;
                m_prev_status = stop;
                break;
            }

            --m_src_vertex;
            m_stroker.calc_join(m_out_vertices,
                                m_src_vertices.next(m_src_vertex),
                                m_src_vertices.curr(m_src_vertex),
                                m_src_vertices.prev(m_src_vertex),
                                m_src_vertices.curr(m_src_vertex).dist,
                                m_src_vertices.prev(m_src_vertex).dist);

            m_prev_status = m_status;
            m_status = out_vertices;
            m_out_vertex = 0;
            break;

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

        case end_poly1:
            m_status = m_prev_status;
            return path_cmd_end_poly | path_flags_close | path_flags_ccw;

        case end_poly2:
            m_status = m_prev_status;
            return path_cmd_end_poly | path_flags_close | path_flags_cw;

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

}