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/**********************************************************************
* $Id: InteriorPointArea.cpp,v 1.14 2004/07/27 16:35:46 strk Exp $
*
* GEOS - Geometry Engine Open Source
* http://geos.refractions.net
*
* Copyright (C) 2001-2002 Vivid Solutions Inc.
*
* This is free software; you can redistribute and/or modify it under
* the terms of the GNU Lesser General Public Licence as published
* by the Free Software Foundation.
* See the COPYING file for more information.
*
**********************************************************************
* $Log: InteriorPointArea.cpp,v $
* Revision 1.14 2004/07/27 16:35:46 strk
* Geometry::getEnvelopeInternal() changed to return a const Envelope *.
* This should reduce object copies as once computed the envelope of a
* geometry remains the same.
*
* Revision 1.13 2004/07/08 19:34:49 strk
* Mirrored JTS interface of CoordinateSequence, factory and
* default implementations.
* Added DefaultCoordinateSequenceFactory::instance() function.
*
* Revision 1.12 2004/07/02 13:28:26 strk
* Fixed all #include lines to reflect headers layout change.
* Added client application build tips in README.
*
* Revision 1.11 2004/07/01 14:12:44 strk
*
* Geometry constructors come now in two flavors:
* - deep-copy args (pass-by-reference)
* - take-ownership of args (pass-by-pointer)
* Same functionality is available through GeometryFactory,
* including buildGeometry().
*
* Revision 1.10 2004/05/07 14:12:23 strk
* Fixed segfault in destructor
*
* Revision 1.9 2004/03/17 02:00:33 ybychkov
* "Algorithm" upgraded to JTS 1.4
*
* Revision 1.8 2003/11/07 01:23:42 pramsey
* Add standard CVS headers licence notices and copyrights to all cpp and h
* files.
*
* Revision 1.7 2003/10/16 08:50:00 strk
* Memory leak fixes. Improved performance by mean of more calls to
* new getCoordinatesRO() when applicable.
*
*
**********************************************************************/
#include <geos/geosAlgorithm.h>
#include <geos/platform.h>
#include <typeinfo>
namespace geos {
double InteriorPointArea::avg(double a, double b){
return (a+b)/2.0;
}
InteriorPointArea::InteriorPointArea(const Geometry *g) {
interiorPoint=NULL;
maxWidth=0.0;
factory=g->getFactory();
add(g);
}
InteriorPointArea::~InteriorPointArea() {
//delete factory;
}
Coordinate* InteriorPointArea::getInteriorPoint() const {
return interiorPoint;
}
/**
* Tests the interior vertices (if any)
* defined by a linear Geometry for the best inside point.
* If a Geometry is not of dimension 1 it is not tested.
* @param geom the geometry to add
*/
void InteriorPointArea::add(const Geometry *geom) {
if (typeid(*geom)==typeid(Polygon)) {
addPolygon(geom);
} else if ((typeid(*geom)==typeid(GeometryCollection)) ||
(typeid(*geom)==typeid(MultiPoint)) ||
(typeid(*geom)==typeid(MultiPolygon)) ||
(typeid(*geom)==typeid(MultiLineString))) {
GeometryCollection *gc=(GeometryCollection*) geom;
for(int i=0;i<gc->getNumGeometries();i++) {
add(gc->getGeometryN(i));
}
}
}
/**
* Finds a reasonable point at which to label a Geometry.
* @param geometry the geometry to analyze
* @return the midpoint of the largest intersection between the geometry and
* a line halfway down its envelope
*/
void InteriorPointArea::addPolygon(const Geometry *geometry) {
LineString *bisector=horizontalBisector(geometry);
Geometry *intersections=bisector->intersection(geometry);
const Geometry *widestIntersection=widestGeometry(intersections);
const Envelope *env=widestIntersection->getEnvelopeInternal();
double width=env->getWidth();
if (interiorPoint==NULL || width>maxWidth) {
interiorPoint=centre(env);
maxWidth = width;
}
//delete env;
delete bisector;
delete intersections;
}
//@return if geometry is a collection, the widest sub-geometry; otherwise,
//the geometry itself
const Geometry* InteriorPointArea::widestGeometry(const Geometry *geometry) {
if ((typeid(*geometry)==typeid(GeometryCollection)) ||
(typeid(*geometry)==typeid(MultiPoint)) ||
(typeid(*geometry)==typeid(MultiPolygon)) ||
(typeid(*geometry)==typeid(MultiLineString))) {
return widestGeometry((GeometryCollection*) geometry);
} else {
return geometry;
}
}
const Geometry*
InteriorPointArea::widestGeometry(const GeometryCollection* gc) {
if (gc->isEmpty()) {
return gc;
}
const Geometry* widestGeometry=gc->getGeometryN(0);
for(int i=1;i<gc->getNumGeometries();i++) { //Start at 1
const Envelope *env1(gc->getGeometryN(i)->getEnvelopeInternal());
const Envelope *env2(widestGeometry->getEnvelopeInternal());
if (env1->getWidth()>env2->getWidth()) {
widestGeometry=gc->getGeometryN(i);
}
}
return widestGeometry;
}
LineString* InteriorPointArea::horizontalBisector(const Geometry *geometry) {
const Envelope *envelope=geometry->getEnvelopeInternal();
// Assert: for areas, minx <> maxx
double avgY=avg(envelope->getMinY(),envelope->getMaxY());
vector<Coordinate>*cv=new vector<Coordinate>(2);
(*cv)[0].x = envelope->getMinX();
(*cv)[0].y = avgY;
(*cv)[1].x = envelope->getMaxX();
(*cv)[1].y = avgY;
//delete envelope;
CoordinateSequence *cl = factory->getCoordinateSequenceFactory()->create(cv);
LineString *ret = factory->createLineString(cl);
//delete cl;
return ret;
}
/**
* Returns the centre point of the envelope.
* @param envelope the envelope to analyze
* @return the centre of the envelope
*/
Coordinate* InteriorPointArea::centre(const Envelope *envelope) const {
return new Coordinate(avg(envelope->getMinX(),
envelope->getMaxX()),
avg(envelope->getMinY(),
envelope->getMaxY()));
}
}
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