mapnik/utils/shapeindex/quadtree.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: quadtree.hh 17 2005-03-08 23:58:43Z pavlenko $

#ifndef QUADTREE_HH
#define QUADTREE_HH

#include "envelope.hpp"
#include <vector>
#include <fstream>

using namespace mapnik;

template <typename T>
struct quadtree_node
{
    Envelope<double> ext_;
    std::vector<T> data_;
    quadtree_node<T>* children_[4];
    quadtree_node(const Envelope<double>& ext)
        : ext_(ext),data_()
    {
        memset(children_,0,sizeof(quadtree_node<T>*)*4);
    }

    ~quadtree_node() 
    {
	for (int i=0;i<4;++i) 
	{
	    if (children_[i]) 
	    {
		delete children_[i],children_[i]=0;
	    }
	}
    }

    int num_subnodes() const 
    {
	int count=0;
	for (int i=0;i<4;++i) 
	{
	    if (children_[i]) 
	    {
		++count;
	    }
	}
	return count;
    }     
};

template <typename T>
class quadtree
{
private:
    quadtree_node<T>* root_;
    const int maxdepth_;
    const double ratio_;
public:
    quadtree(const Envelope<double>& extent,int maxdepth,double ratio)
	: root_(new quadtree_node<T>(extent)),
	  maxdepth_(maxdepth),
	  ratio_(ratio){}
    ~quadtree()
    {
	if (root_) delete root_;
    }
    void insert(const T& data,const Envelope<double>& item_ext)
    {
	insert(data,item_ext,root_,maxdepth_);
    }
    int count() const
    {
	return count_nodes(root_);
    }
    int count_items() const 
    {
	int count=0;
	count_items(root_,count);
	return count;
    }
    void print() const
    {
	print(root_);
    }
    void trim() 
    {
	trim_tree(root_);
    }     
    
    void write(std::ostream& out)
    {
	char header[16];
	memset(header,0,16);
	header[0]='m';
	header[1]='a';
	header[2]='p';
	header[4]='n';
	header[5]='i';
	header[6]='k';
	out.write(header,16);
	write_node(out,root_);
    }

private:

    void trim_tree(quadtree_node<T>*&  node)
    {   
	if (node) 
	{
	    for (int i=0;i<4;++i)
	    {	
		trim_tree(node->children_[i]);	
	    }

	    if (node->num_subnodes()==1 && node->data_.size()==0)
	    {
		for (int i=0;i<4;++i) 
		{
		    if (node->children_[i])
		    {   
			node=node->children_[i];
			break;	
		    }
		}
	    }	
	}
    }

    int count_nodes(const quadtree_node<T>*  node) const
    {
	if (!node)
	{
	    return 0;
	}
	else
	{
	    int count = 1;
	    for (int i=0;i<4;++i)
	    {
		count += count_nodes(node->children_[i]);
	    }
	    return count;
	}
    }

    void count_items(const quadtree_node<T>* node,int& count) const
    {
	if (node)
	{
	    count += node->data_.size();    
	    for (int i=0;i<4;++i)
	    {
		count_items(node->children_[i],count);
	    }    
	}
    }

    int subnode_offset(const quadtree_node<T>* node) const
    {
	int offset=0;
	for (int i=0;i<4;i++)
	{
	    if (node->children_[i])
	    {
		offset +=sizeof(Envelope<double>)+(node->children_[i]->data_.size()*sizeof(T))+3*sizeof(int);
		offset +=subnode_offset(node->children_[i]);
	    }
	}
	return offset;
    }

    void write_node(std::ostream& out,const quadtree_node<T>* node) const
    {
	if (node)
	{
	    int offset=subnode_offset(node);
	    int shape_count=node->data_.size();
	    int recsize=sizeof(Envelope<double>) + 3 * sizeof(int) + shape_count * sizeof(T);
	    char* node_record=new char[recsize];
	    memset(node_record,0,recsize);
	    memcpy(node_record,&offset,4);
	    memcpy(node_record+4,&node->ext_,sizeof(Envelope<double>));
	    memcpy(node_record+36,&shape_count,4);
	    for (int i=0;i<shape_count;++i)
	    {
		memcpy(node_record + 40 + i * sizeof(T),&(node->data_[i]),sizeof(T));
	    }
	    int num_subnodes=0;
	    for (int i=0;i<4;++i)
	    {
		if (node->children_[i])
		{
		    ++num_subnodes;
		}
	    }
	    memcpy(node_record + 40 + shape_count * sizeof(T),&num_subnodes,4);
	    out.write(node_record,recsize);
	    delete [] node_record;

	    for (int i=0;i<4;++i)
	    {
		write_node(out,node->children_[i]);
	    }
	}
    }

    void print(const quadtree_node<T>* node,int level=0) const
    {
	if (node)
	{
	    typename std::vector<T>::const_iterator itr=node->data_.begin();
	    std::string pad;
	    for (int i=0;i<level;++i)
	    {
		pad+=" ";
	    }
	    std::cout<<pad<<"node "<<node<<" extent:"<<node->ext_<<std::endl;
	    std::cout<<pad;
	    while(itr!=node->data_.end())
	    {
		std::cout<<*itr<<" ";
		++itr;
	    }
	    std::cout<<std::endl;
	    for (int i=0;i<4;++i)
	    {
		print(node->children_[i],level+4);
	    }
	}
    }

    void insert(const T& data,const Envelope<double>& item_ext,quadtree_node<T>*  node,int maxdepth)
    {
	if (node && node->ext_.contains(item_ext))
	{
	    coord2d c=node->ext_.center();

	    double width=node->ext_.width();
	    double height=node->ext_.height();

	    double lox=node->ext_.minx();
	    double loy=node->ext_.miny();
	    double hix=node->ext_.maxx();
	    double hiy=node->ext_.maxy();

	    Envelope<double> ext[4];
	    ext[0]=Envelope<double>(lox,loy,lox + width * ratio_,loy + height * ratio_);
	    ext[1]=Envelope<double>(hix - width * ratio_,loy,hix,loy + height * ratio_);
	    ext[2]=Envelope<double>(lox,hiy - height*ratio_,lox + width * ratio_,hiy);
	    ext[3]=Envelope<double>(hix - width * ratio_,hiy - height*ratio_,hix,hiy);

	    if (maxdepth > 1)
	    {
		for (int i=0;i<4;++i)
		{
		    if (ext[i].contains(item_ext))
		    {
			if (!node->children_[i])
			{
			    node->children_[i]=new quadtree_node<T>(ext[i]);
			}
			insert(data,item_ext,node->children_[i],maxdepth-1);
			return;
		    }
		}
	    }
	    node->data_.push_back(data);
	}
    }
};
#endif                                            //QUADTREE_HH