mapnik/datasources/shape/shapefile.hpp

/* This file is part of Mapnik (c++ mapping toolkit)
 * Copyright (C) 2005 Artem Pavlenko
 *
 * Mapnik is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */

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

#ifndef SHAPEFILE_HH
#define SHAPEFILE_HH

#include <fstream>

#include "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 shape_file::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_HH