mapnik/deps/agg/include/agg_conv_clipper.h

/*******************************************************************************
 *                                                                              *
 * Author    :  Angus Johnson                                                   *
 * Version   :  1.1                                                             *
 * Date      :  4 April 2011                                                    *
 * Website   :  http://www.angusj.com                                           *
 * Copyright :  Angus Johnson 2010-2011                                         *
 *                                                                              *
 * License:                                                                     *
 * Use, modification & distribution is subject to Boost Software License Ver 1. *
 * http://www.boost.org/LICENSE_1_0.txt                                         *
 *                                                                              *
 *******************************************************************************/

#ifndef AGG_CONV_CLIPPER_INCLUDED
#define AGG_CONV_CLIPPER_INCLUDED

#include <cmath>
#include "agg_basics.h"
#include "agg_array.h"
#include "clipper.hpp"

namespace agg
{
enum clipper_op_e { clipper_or,
                    clipper_and, clipper_xor, clipper_a_minus_b, clipper_b_minus_a };
enum clipper_PolyFillType {clipper_even_odd, clipper_non_zero, clipper_positive, clipper_negative};

template<class VSA, class VSB> class conv_clipper
{
    enum status { status_move_to, status_line_to, status_close_path, status_stop };
    typedef VSA source_a_type;
    typedef VSB source_b_type;
    typedef conv_clipper<source_a_type, source_b_type> self_type;

private:
    source_a_type*                                          m_src_a;
    source_b_type*                                          m_src_b;
    status                                                  m_status;
    int                                                     m_vertex;
    int                                                     m_contour;
    int                                                     m_scaling_factor;
    clipper_op_e                                            m_operation;
    pod_bvector<ClipperLib::IntPoint, 8>                    m_vertex_accumulator;
    ClipperLib::Polygons                                    m_poly_a;
    ClipperLib::Polygons                                    m_poly_b;
    ClipperLib::Polygons                                    m_result;
    ClipperLib::Clipper                                     m_clipper;
    clipper_PolyFillType                                    m_subjFillType;
    clipper_PolyFillType                                    m_clipFillType;

    int Round(double val)
    {
        if ((val < 0)) return (int)(val - 0.5); else return (int)(val + 0.5);
    }

public:
    conv_clipper(source_a_type &a, source_b_type &b,
                 clipper_op_e op = clipper_or,
                 clipper_PolyFillType subjFillType = clipper_even_odd,
                 clipper_PolyFillType clipFillType = clipper_even_odd,
                 int scaling_factor = 2) :
        m_src_a(&a),
        m_src_b(&b),
        m_status(status_move_to),
        m_vertex(-1),
        m_contour(-1),
        m_operation(op),
        m_subjFillType(subjFillType),
        m_clipFillType(clipFillType)
    {
        m_scaling_factor = std::max(std::min(scaling_factor, 6),0);
        m_scaling_factor = Round(std::pow((double)10, m_scaling_factor));
    }

    conv_clipper(source_a_type &a,
                 clipper_op_e op = clipper_and,
                 clipper_PolyFillType subjFillType = clipper_non_zero,
                 clipper_PolyFillType clipFillType = clipper_non_zero,
                 int scaling_factor = 6) :
        m_src_a(&a),
        m_status(status_move_to),
        m_vertex(-1),
        m_contour(-1),
        m_operation(op),
        m_subjFillType(subjFillType),
        m_clipFillType(clipFillType)
    {
        m_scaling_factor = std::max(std::min(scaling_factor, 6),0);
        m_scaling_factor = Round(std::pow((double)10, m_scaling_factor));
    }

    ~conv_clipper()
    {
    }
    unsigned type() const { return m_src_a->type(); }
    void attach1(VSA &source, clipper_PolyFillType subjFillType = clipper_even_odd)
    { m_src_a = &source; m_subjFillType = subjFillType; }
    void attach2(VSB &source, clipper_PolyFillType clipFillType = clipper_even_odd)
    { m_src_b = &source; m_clipFillType = clipFillType; }

    void operation(clipper_op_e v) { m_operation = v; }

    void rewind(unsigned path_id);
    unsigned vertex(double* x, double* y);

    bool next_contour();
    bool next_vertex(double* x, double* y);
    void start_extracting();
    void add_vertex_(double &x, double &y);
    void end_contour(ClipperLib::Polygons &p);

    template<class VS> void add(VS &src, ClipperLib::Polygons &p){
        unsigned cmd;
        double x; double y; double start_x; double start_y;
        bool starting_first_line;

        start_x = 0.0;
        start_y = 0.0;
        starting_first_line = true;
        p.resize(0);

        cmd = src->vertex( &x , &y );
        while(!is_stop(cmd))
        {
            if(is_vertex(cmd))
            {
                if(is_move_to(cmd))
                {
                    if(!starting_first_line ) end_contour(p);
                    start_x = x;
                    start_y = y;
                }
                add_vertex_( x, y );
                starting_first_line = false;
            }
            else if(is_end_poly(cmd))
            {
                if(!starting_first_line && is_closed(cmd))
                    add_vertex_( start_x, start_y );
            }
            cmd = src->vertex( &x, &y );
        }
        end_contour(p);
    }
};

//------------------------------------------------------------------------

template<class VSA, class VSB>
void conv_clipper<VSA, VSB>::start_extracting()
{
    m_status = status_move_to;
    m_contour = -1;
    m_vertex = -1;
}
//------------------------------------------------------------------------------

template<class VSA, class VSB>
void conv_clipper<VSA, VSB>::rewind(unsigned path_id)
{
    m_src_a->rewind( path_id );
    m_src_b->rewind( path_id );

    add( m_src_a , m_poly_a );
    add( m_src_b , m_poly_b );
    m_result.resize(0);

    ClipperLib::PolyFillType pftSubj, pftClip;
    switch (m_subjFillType)
    {
    case clipper_even_odd: pftSubj = ClipperLib::pftEvenOdd; break;
    case clipper_non_zero: pftSubj = ClipperLib::pftNonZero; break;
    case clipper_positive: pftSubj = ClipperLib::pftPositive; break;
    default: pftSubj = ClipperLib::pftNegative;
    }
    switch (m_clipFillType)
    {
    case clipper_even_odd: pftClip = ClipperLib::pftEvenOdd; break;
    case clipper_non_zero: pftClip = ClipperLib::pftNonZero; break;
    case clipper_positive: pftClip = ClipperLib::pftPositive; break;
    default: pftClip = ClipperLib::pftNegative;
    }

    m_clipper.Clear();
    switch( m_operation ) {
    case clipper_or:
    {
        m_clipper.AddPolygons( m_poly_a , ClipperLib::ptSubject );
        m_clipper.AddPolygons( m_poly_b , ClipperLib::ptClip );
        m_clipper.Execute( ClipperLib::ctUnion , m_result , pftSubj, pftClip);
        break;
    }
    case clipper_and:
    {
        m_clipper.AddPolygons( m_poly_a , ClipperLib::ptSubject );
        m_clipper.AddPolygons( m_poly_b , ClipperLib::ptClip );
        m_clipper.Execute( ClipperLib::ctIntersection , m_result, pftSubj, pftClip );
        break;
    }
    case clipper_xor:
    {
        m_clipper.AddPolygons( m_poly_a , ClipperLib::ptSubject );
        m_clipper.AddPolygons( m_poly_b , ClipperLib::ptClip );
        m_clipper.Execute( ClipperLib::ctXor , m_result, pftSubj, pftClip );
        break;
    }
    case clipper_a_minus_b:
    {
        m_clipper.AddPolygons( m_poly_a , ClipperLib::ptSubject );
        m_clipper.AddPolygons( m_poly_b , ClipperLib::ptClip );
        m_clipper.Execute( ClipperLib::ctDifference , m_result, pftSubj, pftClip );
        break;
    }
    case clipper_b_minus_a:
    {
        m_clipper.AddPolygons( m_poly_b , ClipperLib::ptSubject );
        m_clipper.AddPolygons( m_poly_a , ClipperLib::ptClip );
        m_clipper.Execute( ClipperLib::ctDifference , m_result, pftSubj, pftClip );
        break;
    }
    }
    start_extracting();
}
//------------------------------------------------------------------------------

template<class VSA, class VSB>
void conv_clipper<VSA, VSB>::end_contour( ClipperLib::Polygons &p)
{
    unsigned i, len;

    if( m_vertex_accumulator.size() < 3 ) return;
    len = p.size();
    p.resize(len+1);
    p[len].resize(m_vertex_accumulator.size());
    for( i = 0 ; i < m_vertex_accumulator.size() ; i++ )
        p[len][i] = m_vertex_accumulator[i];
    m_vertex_accumulator.remove_all();
}
//------------------------------------------------------------------------------

template<class VSA, class VSB>
void conv_clipper<VSA, VSB>::add_vertex_(double &x, double &y)
{
    ClipperLib::IntPoint v;

    v.X = Round(x * m_scaling_factor);
    v.Y = Round(y * m_scaling_factor);
    m_vertex_accumulator.add( v );
}
//------------------------------------------------------------------------------

template<class VSA, class VSB>
bool conv_clipper<VSA, VSB>::next_contour()
{
    m_contour++;
    if(m_contour >= (int)m_result.size()) return false;
    m_vertex =-1;
    return true;
}
//------------------------------------------------------------------------------

template<class VSA, class VSB>
bool conv_clipper<VSA, VSB>::next_vertex(double *x, double *y)
{
    m_vertex++;
    if(m_vertex >= (int)m_result[m_contour].size()) return false;
    *x = (double)m_result[ m_contour ][ m_vertex ].X / m_scaling_factor;
    *y = (double)m_result[ m_contour ][ m_vertex ].Y / m_scaling_factor;
    return true;
}
//------------------------------------------------------------------------------

//------------------------------------------------------------------------------

template<class VSA, class VSB>
unsigned conv_clipper<VSA, VSB>::vertex(double *x, double *y)
{
    switch (m_status)
    {
    case status_move_to:
    {
        if( next_contour() )
        {
            if ( next_vertex( x, y ) )
            {
                m_status = status_line_to;
                return path_cmd_move_to;
            }
            else
            {
                m_status = status_close_path;
                return path_cmd_line_to;
            }
        }
        else
            return path_cmd_stop;
    }
    case status_close_path:
    {
        *x = 0;
        *y = 0;
        m_status = status_move_to;
        return path_cmd_end_poly | path_flags_close;
    }
    case status_stop:
    {
        return path_cmd_stop;
    }
    default:
    {
        if( next_vertex( x, y ) )
        {
            return path_cmd_line_to;
        }
        else
        {
            m_status = status_close_path;
            return path_cmd_line_to;
        }
    }
    }
}
//------------------------------------------------------------------------------


} //namespace agg
#endif //AGG_CONV_CLIPPER_INCLUDED