mapnik/plugins/input/shape/shapefile.hpp

/*****************************************************************************
 * 
 * This file is part of Mapnik (c++ mapping toolkit)
 *
 * Copyright (C) 2006 Artem Pavlenko
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 *****************************************************************************/

//$Id: shapefile.hh 33 2005-04-04 13:01:03Z pavlenko $

#ifndef SHAPEFILE_HPP
#define SHAPEFILE_HPP

#include <fstream>

#include <mapnik/envelope.hpp>

using namespace mapnik;

struct shape_record
{
    char* data;
    size_t size;
    size_t pos;
    explicit shape_record(size_t size)
        : data(static_cast<char*>(::operator new(sizeof(char)*size))),
          size(size),
          pos(0) {}
    
    char* rawdata()
    {
        return &data[0]; 
    }

    void skip(unsigned n)
    {
        pos+=n;
    }

    int read_ndr_integer()
    {
        int val=(data[pos] & 0xff)     | 
            (data[pos+1] & 0xff) << 8  |
            (data[pos+2] & 0xff) << 16 |
            (data[pos+3] & 0xff) << 24;
        pos+=4;
        return val;
    }
    
    int read_xdr_integer()
    {
        int val=(data[pos] & 0xff) << 24 | 
            (data[pos+1] & 0xff)   << 16   |
            (data[pos+2] & 0xff)   << 8    |
            (data[pos+3] & 0xff);
        pos+=4;
        return val;
    }
    
    double read_double()
    {
        double val;		
#ifndef WORDS_BIGENDIAN
        std::memcpy(&val,&data[pos],8);	
#else
       	long long bits = ((long long)data[pos] & 0xff) | 
            ((long long)data[pos+1] & 0xff) << 8   |
            ((long long)data[pos+2] & 0xff) << 16  |
            ((long long)data[pos+3] & 0xff) << 24  |
            ((long long)data[pos+4] & 0xff) << 32  |
            ((long long)data[pos+5] & 0xff) << 40  |
            ((long long)data[pos+6] & 0xff) << 48  |
            ((long long)data[pos+7] & 0xff) << 56  ;
        std::memcpy(&val,&bits,8);
#endif 
        pos+=8;
        return val;
    }
    long remains() 
    {
        return (size-pos);
    }
    ~shape_record() 
    {
        ::operator delete(data);
    }	
};

class shape_file
{  
    std::ifstream file_;
    //static const int buffer_size = 16;
    //char buff_[buffer_size];
public:
    shape_file();
    shape_file(const std::string& file_name);
    ~shape_file();
    bool open(const std::string& file_name);
    bool is_open();
    void close();
    
    inline void read_record(shape_record& rec)
    {
        file_.read(rec.rawdata(),rec.size);  
    }

    inline int read_xdr_integer()
    {
        char b[4];
        file_.read(b, 4);
        return b[3] & 0xffu | (b[2] & 0xffu) << 8 |
            (b[1] & 0xffu) << 16 | (b[0] & 0xffu) << 24;
    }

    inline int read_ndr_integer()
    {
        char b[4];
        file_.read(b,4);
        return b[0]&0xffu | (b[1]&0xffu) << 8 | 
            (b[2]&0xffu) << 16 | (b[3]&0xffu) << 24;
    }

    inline double read_double()
    {
        double val;
#ifndef WORDS_BIGENDIAN
        file_.read(reinterpret_cast<char*>(&val),8);
#else
        char b[8];
        file_.read(b,8);
        long long bits = ((long long)b[0] & 0xff) | 
            ((long long)b[1] & 0xff) << 8   |
            ((long long)b[2] & 0xff) << 16  |
            ((long long)b[3] & 0xff) << 24  |
            ((long long)b[4] & 0xff) << 32  |
            ((long long)b[5] & 0xff) << 40  |
            ((long long)b[6] & 0xff) << 48  |
            ((long long)b[7] & 0xff) << 56  ;
        memcpy(&val,&bits,8);
#endif
        return val;
    }

    inline void read_envelope(Envelope<double>& envelope)
    {
#ifndef WORDS_BIGENDIAN
        file_.read(reinterpret_cast<char*>(&envelope),sizeof(envelope));
#else
        double minx=read_double();
        double miny=read_double();
        double maxx=read_double();
        double maxy=read_double();
        envelope.init(minx,miny,maxx,maxy);
#endif  
    }

    inline void skip(std::streampos bytes)
    {
        file_.seekg(bytes,std::ios::cur);
    }

    inline void rewind()
    {
        seek(100);
    }

    inline void seek(std::streampos pos)
    {
        file_.seekg(pos,std::ios::beg);
    }

    inline std::streampos pos()
    {
        return file_.tellg();
    }

    inline bool is_eof()
    {
        return file_.eof();
    }
    
private:
    shape_file(const shape_file&);
    shape_file& operator=(const shape_file&);
};

#endif //SHAPEFILE_HPP