mapnik/deps/agg/src/agg_vcgen_dash.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
//----------------------------------------------------------------------------
//
// Line dash generator
//
//----------------------------------------------------------------------------

#include <math.h>
#include "agg_vcgen_dash.h"
#include "agg_shorten_path.h"

namespace agg
{

//------------------------------------------------------------------------
vcgen_dash::vcgen_dash() :
    m_total_dash_len(0.0),
    m_num_dashes(0),
    m_dash_start(0.0),
    m_shorten(0.0),
    m_curr_dash_start(0.0),
    m_curr_dash(0),
    m_src_vertices(),
    m_closed(0),
    m_status(initial),
    m_src_vertex(0)
{
}



//------------------------------------------------------------------------
void vcgen_dash::remove_all_dashes()
{
    m_total_dash_len = 0.0;
    m_num_dashes = 0;
    m_curr_dash_start = 0.0;
    m_curr_dash = 0;
}


//------------------------------------------------------------------------
void vcgen_dash::add_dash(double dash_len, double gap_len)
{
    if(m_num_dashes < max_dashes-1)
    {
        m_total_dash_len += dash_len + gap_len;
        m_dashes[m_num_dashes++] = dash_len;
        m_dashes[m_num_dashes++] = gap_len;
    }
}


//------------------------------------------------------------------------
void vcgen_dash::dash_start(double ds)
{
    m_dash_start = ds;
    calc_dash_start(std::fabs(ds));
}


//------------------------------------------------------------------------
void vcgen_dash::calc_dash_start(double ds)
{
    m_curr_dash = 0;
    m_curr_dash_start = 0.0;
    while(ds > 0.0)
    {
        if(ds > m_dashes[m_curr_dash])
        {
            ds -= m_dashes[m_curr_dash];
            ++m_curr_dash;
            m_curr_dash_start = 0.0;
            if(m_curr_dash >= m_num_dashes) m_curr_dash = 0;
        }
        else
        {
            m_curr_dash_start = ds;
            ds = 0.0;
        }
    }
}


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


//------------------------------------------------------------------------
void vcgen_dash::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_dash::rewind(unsigned)
{
    if(m_status == initial)
    {
        m_src_vertices.close(m_closed != 0);
        shorten_path(m_src_vertices, m_shorten, m_closed);
    }
    m_status = ready;
    m_src_vertex = 0;
}


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

        case ready:
            if(m_num_dashes < 2 || m_src_vertices.size() < 2)
            {
                cmd = path_cmd_stop;
                break;
            }
            m_status = polyline;
            m_src_vertex = 1;
            m_v1 = &m_src_vertices[0];
            m_v2 = &m_src_vertices[1];
            m_curr_rest = m_v1->dist;
            *x = m_v1->x;
            *y = m_v1->y;
            if(m_dash_start >= 0.0) calc_dash_start(m_dash_start);
            return path_cmd_move_to;

        case polyline:
        {
            double dash_rest = m_dashes[m_curr_dash] - m_curr_dash_start;

            unsigned cmd2 = (m_curr_dash & 1) ?
                path_cmd_move_to :
                path_cmd_line_to;

            if(m_curr_rest > dash_rest)
            {
                m_curr_rest -= dash_rest;
                ++m_curr_dash;
                if(m_curr_dash >= m_num_dashes) m_curr_dash = 0;
                m_curr_dash_start = 0.0;
                *x = m_v2->x - (m_v2->x - m_v1->x) * m_curr_rest / m_v1->dist;
                *y = m_v2->y - (m_v2->y - m_v1->y) * m_curr_rest / m_v1->dist;
            }
            else
            {
                m_curr_dash_start += m_curr_rest;
                *x = m_v2->x;
                *y = m_v2->y;
                ++m_src_vertex;
                m_v1 = m_v2;
                m_curr_rest = m_v1->dist;
                if(m_closed)
                {
                    if(m_src_vertex > m_src_vertices.size())
                    {
                        m_status = stop;
                    }
                    else
                    {
                        m_v2 = &m_src_vertices
                            [
                                (m_src_vertex >= m_src_vertices.size()) ? 0 :
                                m_src_vertex
                                ];
                    }
                }
                else
                {
                    if(m_src_vertex >= m_src_vertices.size())
                    {
                        m_status = stop;
                    }
                    else
                    {
                        m_v2 = &m_src_vertices[m_src_vertex];
                    }
                }
            }
            return cmd2;
        }
        break;

        case stop:
            cmd = path_cmd_stop;
            break;
        }

    }
    return path_cmd_stop;
}


}