qgsspatialindex.cpp

一个非常好的GIS开源新版本

/***************************************************************************
    qgsspatialindex.cpp  - wrapper class for spatial index library
    ----------------------
    begin                : December 2006
    copyright            : (C) 2006 by Martin Dobias
    email                : wonder.sk at gmail dot com
 ***************************************************************************
 *                                                                         *
 *   This program 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     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/
/* $Id$ */

#include "qgsspatialindex.h"

#include "qgsgeometry.h"
#include "qgsfeature.h"
#include "qgsrect.h"
    
#include "SpatialIndex.h"

using namespace SpatialIndex;


// custom visitor that adds found features to list 
class QgisVisitor : public SpatialIndex::IVisitor
{
public:
  QgisVisitor(QList<int> & list)
  : mList(list) {}

  void visitNode(const INode& n) {}
  
  void visitData(const IData& d)
  {
    mList.append(d.getIdentifier());
  }

  void visitData(std::vector<const IData*>& v) {}

private:
  QList<int>& mList;
};


QgsSpatialIndex::QgsSpatialIndex()
{
  // for now only memory manager
  mStorageManager = StorageManager::createNewMemoryStorageManager();

  // create buffer

  unsigned int capacity = 10;
  bool writeThrough = false;
  mStorage = StorageManager::createNewRandomEvictionsBuffer(*mStorageManager, capacity, writeThrough);

  // R-Tree parameters
  double fillFactor = 0.7;
  unsigned long indexCapacity = 10;
  unsigned long leafCapacity = 10;
  unsigned long dimension = 2;
  RTree::RTreeVariant variant = RTree::RV_RSTAR;

  // create R-tree
  long indexId;
  mRTree = RTree::createNewRTree(*mStorage, fillFactor, indexCapacity,
                                 leafCapacity, dimension, variant, indexId);
}

QgsSpatialIndex:: ~QgsSpatialIndex()
{
  delete mRTree;
  delete mStorage;
  delete mStorageManager;
}

Tools::Geometry::Region QgsSpatialIndex::rectToRegion(QgsRect rect)
{
  double pt1[2], pt2[2];
  pt1[0] = rect.xMin();
  pt1[1] = rect.yMin();
  pt2[0] = rect.xMax();
  pt2[1] = rect.yMax();
  return Tools::Geometry::Region(pt1, pt2, 2);
}

bool QgsSpatialIndex::featureInfo(QgsFeature& f, Tools::Geometry::Region& r, long& id)
{
  QgsGeometry* g = f.geometry();
  if (!g)
    return false;

  id = f.featureId();
  r = rectToRegion(g->boundingBox());
  return true;
}

bool QgsSpatialIndex::insertFeature(QgsFeature& f)
{
  Tools::Geometry::Region r;
  long id;
  if (!featureInfo(f, r, id))
    return false;

  // TODO: handle possible exceptions
  mRTree->insertData(0,0, r, id);

  return true;
}

bool QgsSpatialIndex::deleteFeature(QgsFeature& f)
{
  Tools::Geometry::Region r;
  long id;
  if (!featureInfo(f, r, id))
    return false;

  // TODO: handle exceptions
  return mRTree->deleteData(r, id);
}

QList<int> QgsSpatialIndex::intersects(QgsRect rect)
{
  QList<int> list;
  QgisVisitor visitor(list);

  Tools::Geometry::Region r = rectToRegion(rect);

  mRTree->intersectsWithQuery(r, visitor);

  return list;
}

QList<int> QgsSpatialIndex::nearestNeighbor(QgsPoint point, int neighbors)
{
  QList<int> list;
  QgisVisitor visitor(list);

  double pt[2];
  pt[0] = point.x();
  pt[1] = point.y();
  Tools::Geometry::Point p(pt, 2);

  mRTree->nearestNeighborQuery(neighbors, p, visitor);

  return list;
}