mapnik/deps/agg/src/agg_trans_double_path.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_math.h"
#include "agg_trans_double_path.h"

namespace agg
{

//------------------------------------------------------------------------
trans_double_path::trans_double_path() :
    m_base_length(0.0),
    m_base_height(1.0),
    m_kindex1(0.0),
    m_kindex2(0.0),
    m_status1(initial),
    m_status2(initial),
    m_preserve_x_scale(true)
{
}


//------------------------------------------------------------------------
void trans_double_path::reset()
{
    m_src_vertices1.remove_all();
    m_src_vertices2.remove_all();
    m_kindex1 = 0.0;
    m_kindex1 = 0.0;
    m_status1 = initial;
    m_status2 = initial;
}


//------------------------------------------------------------------------
void trans_double_path::move_to1(double x, double y)
{
    if(m_status1 == initial)
    {
        m_src_vertices1.modify_last(vertex_dist(x, y));
        m_status1 = making_path;
    }
    else
    {
        line_to1(x, y);
    }
}


//------------------------------------------------------------------------
void trans_double_path::line_to1(double x, double y)
{
    if(m_status1 == making_path)
    {
        m_src_vertices1.add(vertex_dist(x, y));
    }
}


//------------------------------------------------------------------------
void trans_double_path::move_to2(double x, double y)
{
    if(m_status2 == initial)
    {
        m_src_vertices2.modify_last(vertex_dist(x, y));
        m_status2 = making_path;
    }
    else
    {
        line_to2(x, y);
    }
}


//------------------------------------------------------------------------
void trans_double_path::line_to2(double x, double y)
{
    if(m_status2 == making_path)
    {
        m_src_vertices2.add(vertex_dist(x, y));
    }
}


//------------------------------------------------------------------------
double trans_double_path::finalize_path(vertex_storage& vertices)
{
    unsigned i;
    double dist;
    double d;

    vertices.close(false);
    if(vertices.size() > 2)
    {
        if(vertices[vertices.size() - 2].dist * 10.0 <
           vertices[vertices.size() - 3].dist)
        {
            d = vertices[vertices.size() - 3].dist +
                vertices[vertices.size() - 2].dist;

            vertices[vertices.size() - 2] =
                vertices[vertices.size() - 1];

            vertices.remove_last();
            vertices[vertices.size() - 2].dist = d;
        }
    }

    dist = 0;
    for(i = 0; i < vertices.size(); i++)
    {
        vertex_dist& v = vertices[i];
        d = v.dist;
        v.dist = dist;
        dist += d;
    }

    return (vertices.size() - 1) / dist;
}


//------------------------------------------------------------------------
void trans_double_path::finalize_paths()
{
    if(m_status1 == making_path && m_src_vertices1.size() > 1 &&
       m_status2 == making_path && m_src_vertices2.size() > 1)
    {
        m_kindex1 = finalize_path(m_src_vertices1);
        m_kindex2 = finalize_path(m_src_vertices2);
        m_status1 = ready;
        m_status2 = ready;
    }
}


//------------------------------------------------------------------------
double trans_double_path::total_length1() const
{
    if(m_base_length >= 1e-10) return m_base_length;
    return (m_status1 == ready) ?
        m_src_vertices1[m_src_vertices1.size() - 1].dist :
        0.0;
}


//------------------------------------------------------------------------
double trans_double_path::total_length2() const
{
    if(m_base_length >= 1e-10) return m_base_length;
    return (m_status2 == ready) ?
        m_src_vertices2[m_src_vertices2.size() - 1].dist :
        0.0;
}


//------------------------------------------------------------------------
void trans_double_path::transform1(const vertex_storage& vertices,
                                   double kindex, double kx,
                                   double *x, double* y) const
{
    double x1 = 0.0;
    double y1 = 0.0;
    double dx = 1.0;
    double dy = 1.0;
    double d  = 0.0;
    double dd = 1.0;
    *x *= kx;
    if(*x < 0.0)
    {
        // Extrapolation on the left
        //--------------------------
        x1 = vertices[0].x;
        y1 = vertices[0].y;
        dx = vertices[1].x - x1;
        dy = vertices[1].y - y1;
        dd = vertices[1].dist - vertices[0].dist;
        d  = *x;
    }
    else
        if(*x > vertices[vertices.size() - 1].dist)
        {
            // Extrapolation on the right
            //--------------------------
            unsigned i = vertices.size() - 2;
            unsigned j = vertices.size() - 1;
            x1 = vertices[j].x;
            y1 = vertices[j].y;
            dx = x1 - vertices[i].x;
            dy = y1 - vertices[i].y;
            dd = vertices[j].dist - vertices[i].dist;
            d  = *x - vertices[j].dist;
        }
        else
        {
            // Interpolation
            //--------------------------
            unsigned i = 0;
            unsigned j = vertices.size() - 1;
            if(m_preserve_x_scale)
            {
                unsigned k;
                for(i = 0; (j - i) > 1; )
                {
                    if(*x < vertices[k = (i + j) >> 1].dist)
                    {
                        j = k;
                    }
                    else
                    {
                        i = k;
                    }
                }
                d  = vertices[i].dist;
                dd = vertices[j].dist - d;
                d  = *x - d;
            }
            else
            {
                i = unsigned(*x * kindex);
                j = i + 1;
                dd = vertices[j].dist - vertices[i].dist;
                d = ((*x * kindex) - i) * dd;
            }
            x1 = vertices[i].x;
            y1 = vertices[i].y;
            dx = vertices[j].x - x1;
            dy = vertices[j].y - y1;
        }
    *x = x1 + dx * d / dd;
    *y = y1 + dy * d / dd;
}


//------------------------------------------------------------------------
void trans_double_path::transform(double *x, double *y) const
{
    if(m_status1 == ready && m_status2 == ready)
    {
        if(m_base_length > 1e-10)
        {
            *x *= m_src_vertices1[m_src_vertices1.size() - 1].dist /
                m_base_length;
        }

        double x1 = *x;
        double y1 = *y;
        double x2 = *x;
        double y2 = *y;
        double dd = m_src_vertices2[m_src_vertices2.size() - 1].dist /
            m_src_vertices1[m_src_vertices1.size() - 1].dist;

        transform1(m_src_vertices1, m_kindex1, 1.0, &x1, &y1);
        transform1(m_src_vertices2, m_kindex2, dd,  &x2, &y2);

        *x = x1 + *y * (x2 - x1) / m_base_height;
        *y = y1 + *y * (y2 - y1) / m_base_height;
    }
}

}