mapnik/include/vertex_vector.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.#include "memory.hpp"
 *
 * 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.
 */

//  Credits:
//  I gratefully acknowledge the inspiring work of Maxim Shemanarev (McSeem), 
//  author of Anti-Grain Geometry (http://www.antigrain.com). I have used 
//  the datastructure from AGG as a template for my own. 


//$Id: vertex_vector.hpp 39 2005-04-10 20:39:53Z pavlenko $

#ifndef VERTEX_VECTOR_HPP
#define VERTEX_VECTOT_HPP

#include "vertex.hpp"
#include "ctrans.hpp"

namespace mapnik
{
    template <typename T>
    class vertex_vector 
    {
	typedef typename T::type value_type;
	typedef vertex<value_type,2> vertex_type;
	enum {
	    block_shift = 8,
	    block_size  = 1<<block_shift,
	    block_mask  = block_size - 1,
	    grow_by     = 256
	};

    private:
	unsigned num_blocks_;
	unsigned max_blocks_;
	value_type** vertexs_;
	unsigned char** commands_;
	unsigned pos_;
    public:
	
	vertex_vector() 
	    : num_blocks_(0),
	      max_blocks_(0),
	      vertexs_(0),
	      commands_(0),
	      pos_(0) {}

	~vertex_vector()
	{
	    if ( num_blocks_ )
	    {
		value_type** vertexs=vertexs_ + num_blocks_ - 1;
		while ( num_blocks_-- )
		{
		    delete [] *vertexs;
		    --vertexs;
		}
		delete [] vertexs_;
	    }
	}
	unsigned size() const 
	{
	    return pos_;
	}
	
	void push_back (value_type x,value_type y,unsigned command)
	{
	    unsigned block = pos_ >> block_shift;
	    if (block >= num_blocks_)
	    {
		allocate_block(block);
	    }
	    value_type* vertex = vertexs_[block] + ((pos_ & block_mask) << 1);
	    unsigned char* cmd= commands_[block] + (pos_ & block_mask);
	    
	    *cmd = static_cast<unsigned char>(command);
	    *vertex++ = x;
	    *vertex   = y;
	    ++pos_;
	}
	unsigned get_vertex(unsigned pos,value_type* x,value_type* y) const
	{
	    if (pos >= pos_) return SEG_END;
	    unsigned block = pos >> block_shift;
	    const value_type* vertex = vertexs_[block] + (( pos & block_mask) << 1);
	    *x = (*vertex++);
	    *y = (*vertex);
	    return commands_[block] [pos & block_mask];
	}
	unsigned get_at(unsigned pos,value_type& x,value_type& y) const
	{
	    if (pos >= pos_) return SEG_END;
	    unsigned block = pos >> block_shift;
	    const value_type* vertex = vertexs_[block] + (( pos & block_mask) << 1);
	    x = (*vertex++);
	    y = (*vertex);
	    return commands_[block] [pos & block_mask];
	}
	    
	unsigned get_at(unsigned pos,vertex_type& v) const 
	{
	    if (pos >= pos_) return SEG_END;
	    unsigned block = pos >> block_shift;
	    const value_type* vertex = vertexs_[block] + (( pos & block_mask) << 1);
	    unsigned char* cmd= commands_[block] + (pos_ & block_mask);
	    v.x=(*vertex++);
	    v.y=(*vertex);
	    return commands_[block] [pos & block_mask];
	}
	
	void transform_at(unsigned pos,const CoordTransform& t)
	{
	    if (pos >= pos_) return;
	    unsigned block = pos >> block_shift;
	    value_type* vertex = vertexs_[block] + (( pos & block_mask) << 1);
	    t.forward_x(vertex);
	    ++vertex;
	    t.forward_y(vertex);
	}
	
    private:
	vertex_vector(const vertex_vector&);
	vertex_vector& operator=(const vertex_vector&);
	void allocate_block(unsigned block)
	{
	    if (block >= max_blocks_)
	    {
		value_type** new_vertexs = new value_type* [(max_blocks_ + grow_by) * 2];
		unsigned char** new_commands = (unsigned char**)(new_vertexs + max_blocks_ + grow_by);
		if (vertexs_)
		{
		    std::memcpy(new_vertexs,vertexs_,max_blocks_ * sizeof(value_type*));
		    std::memcpy(new_commands,commands_,max_blocks_ * sizeof(unsigned char*));
		    delete [] vertexs_;
		}
		vertexs_ = new_vertexs;
		commands_ = new_commands;
		max_blocks_ += grow_by;
	    }
	    vertexs_[block] = new value_type [block_size * 2 + block_size / (sizeof(value_type))];
	    commands_[block] = (unsigned char*)(vertexs_[block] + block_size*2);
	    ++num_blocks_;
	}
    };
}

#endif //VERTEX_VECTOR_HPP