buffersubgraph.cpp

来自「一个很好的vc底层代码」· C++ 代码 · 共 318 行

/**********************************************************************
 * $Id: BufferSubgraph.cpp,v 1.12.2.1 2005/06/30 18:31:21 strk Exp $
 *
 * GEOS - Geometry Engine Open Source
 * http://geos.refractions.net
 *
 * Copyright (C) 2001-2002 Vivid Solutions Inc.
 * Copyright (C) 2005 Refractions Research 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.
 *
 **********************************************************************/

#include <geos/opBuffer.h>

namespace geos {
BufferSubgraph::BufferSubgraph(CGAlgorithms *cga):
	finder(new RightmostEdgeFinder(cga)),
	dirEdgeList(new vector<DirectedEdge*>()),
	nodes(new vector<Node*>()),
	rightMostCoord(NULL),
	env(NULL)
{
	//dirEdgeList=new vector<DirectedEdge*>();
	//nodes=new vector<Node*>();
	//rightMostCoord=NULL;
	//finder=new RightmostEdgeFinder(cga);
}

BufferSubgraph::~BufferSubgraph() {
	delete dirEdgeList;
	delete nodes;
	delete finder;
	delete env;
}

vector<DirectedEdge*>* BufferSubgraph::getDirectedEdges() { 
	return dirEdgeList;
}

vector<Node*>* BufferSubgraph::getNodes() { 
	return nodes;
}

/**
* Gets the rightmost coordinate in the edges of the subgraph
*/
Coordinate* BufferSubgraph::getRightmostCoordinate() {
	return rightMostCoord;
}

/**
* Creates the subgraph consisting of all edges reachable from this node.
* Finds the edges in the graph and the rightmost coordinate.
*
* @param node a node to start the graph traversal from
*/
void BufferSubgraph::create(Node *node) {
	addReachable(node);
	finder->findEdge(dirEdgeList);
	rightMostCoord=&(finder->getCoordinate());
}

/**
* Adds all nodes and edges reachable from this node to the subgraph.
* Uses an explicit stack to avoid a large depth of recursion.
*
* @param node a node known to be in the subgraph
*/
void BufferSubgraph::addReachable(Node *startNode) {
	vector<Node*> *nodeStack=new vector<Node*>();
	nodeStack->push_back(startNode);
	while (!nodeStack->empty()) {
		Node *node=*(nodeStack->end()-1);
		nodeStack->pop_back();
		add(node, nodeStack);
	}
	delete nodeStack;
}

/**
* Adds the argument node and all its out edges to the subgraph
* @param node the node to add
* @param nodeStack the current set of nodes being traversed
*/
void BufferSubgraph::add(Node *node, vector<Node*> *nodeStack){
	node->setVisited(true);
	nodes->push_back(node);
	vector<EdgeEnd*> *ees=node->getEdges()->getEdges();
	for(int i=0;i<(int)ees->size();i++) {
		DirectedEdge *de=(DirectedEdge*) (*ees)[i];
		dirEdgeList->push_back(de);
		DirectedEdge *sym=de->getSym();
		Node *symNode=sym->getNode();
		/**
		* NOTE: this is a depth-first traversal of the graph.
		* This will cause a large depth of recursion.
		* It might be better to do a breadth-first traversal.
		*/
		if (! symNode->isVisited()) nodeStack->push_back(symNode);
	}
}

void BufferSubgraph::clearVisitedEdges() {
	unsigned int size = dirEdgeList->size();
	for(int i=0; i<size; ++i)
	{
		DirectedEdge *de=(*dirEdgeList)[i];
		de->setVisited(false);
	}
}

void BufferSubgraph::computeDepth(int outsideDepth) {
	clearVisitedEdges();
	// find an outside edge to assign depth to
	DirectedEdge *de=finder->getEdge();
	//Node *n=de->getNode();
	//Label *label=de->getLabel();
	// right side of line returned by finder is on the outside
	de->setEdgeDepths(Position::RIGHT, outsideDepth);
	copySymDepths(de);
	//computeNodeDepth(n, de);
	computeDepths(de);
}

void
BufferSubgraph::computeNodeDepth(Node *n)
	// throw(TopologyException *)
{
	// find a visited dirEdge to start at
	DirectedEdge *startEdge=NULL;
	vector<EdgeEnd*> *ees=n->getEdges()->getEdges();
	for(int i=0;i<(int)ees->size();i++) {
		DirectedEdge *de=(DirectedEdge*) (*ees)[i];
		if (de->isVisited() || de->getSym()->isVisited()) {
			startEdge=de;
			break;
		}
	}
	// MD - testing  Result: breaks algorithm
	//if (startEdge==null) return;
	Assert::isTrue(startEdge!=NULL, "unable to find edge to compute depths at " + n->getCoordinate().toString());
	((DirectedEdgeStar*) n->getEdges())->computeDepths(startEdge);
	// copy depths to sym edges
	vector<EdgeEnd*> *ees1=n->getEdges()->getEdges();
	for(int j=0;j<(int)ees1->size();j++) {
		DirectedEdge *de=(DirectedEdge*) (*ees)[j];
		de->setVisited(true);
		copySymDepths(de);
	}
}

void BufferSubgraph::copySymDepths(DirectedEdge *de){
	DirectedEdge *sym=de->getSym();
	sym->setDepth(Position::LEFT, de->getDepth(Position::RIGHT));
	sym->setDepth(Position::RIGHT, de->getDepth(Position::LEFT));
}

/**
* Find all edges whose depths indicates that they are in the result area(s).
* Since we want polygon shells to be
* oriented CW, choose dirEdges with the interior of the result on the RHS.
* Mark them as being in the result.
* Interior Area edges are the result of dimensional collapses.
* They do not form part of the result area boundary.
*/
void BufferSubgraph::findResultEdges() {
	for(int i=0;i<(int)dirEdgeList->size();i++) {
		DirectedEdge *de=(*dirEdgeList)[i];
		/**
		* Select edges which have an interior depth on the RHS
		* and an exterior depth on the LHS.
		* Note that because of weird rounding effects there may be
		* edges which have negative depths!  Negative depths
		* count as "outside".
		*/
		// <FIX> - handle negative depths
		if (	de->getDepth(Position::RIGHT)>=1
			&&  de->getDepth(Position::LEFT)<=0
			&& !de->isInteriorAreaEdge()) {
					de->setInResult(true);
					//Debug.print("in result "); Debug.println(de);
		}
	}
}

/**
* BufferSubgraphs are compared on the x-value of their rightmost Coordinate.
* This defines a partial ordering on the graphs such that:
* <p>
* g1 >= g2 <==> Ring(g2) does not contain Ring(g1)
* <p>
* where Polygon(g) is the buffer polygon that is built from g.
* <p>
* This relationship is used to sort the BufferSubgraphs so that shells are guaranteed to
* be built before holes.
*/
int BufferSubgraph::compareTo(void* o) {
	BufferSubgraph *graph=(BufferSubgraph*) o;
	if (rightMostCoord->x<graph->rightMostCoord->x) {
		return -1;
	}
	if (rightMostCoord->x>graph->rightMostCoord->x) {
		return 1;
	}
	return 0;
}

/**
* Compute depths for all dirEdges via breadth-first traversal of nodes in graph
* @param startEdge edge to start processing with
*/
// <FIX> MD - use iteration & queue rather than recursion, for speed and robustness
void BufferSubgraph::computeDepths(DirectedEdge *startEdge){
	vector<Node*> nodesVisited; //Used to be a HashSet
	vector<Node*> nodeQueue;
	Node *startNode=startEdge->getNode();
	nodeQueue.push_back(startNode);
	nodesVisited.push_back(startNode);
	startEdge->setVisited(true);

	while (! nodeQueue.empty()) {
		//System.out.println(nodes.size() + " queue: " + nodeQueue.size());
		Node *n=nodeQueue[0];
		nodeQueue.erase(nodeQueue.begin());
		nodesVisited.push_back(n);

		// compute depths around node, starting at this edge since it has depths assigned
		computeNodeDepth(n);

		// add all adjacent nodes to process queue,
		// unless the node has been visited already
		vector<EdgeEnd*> *ees=n->getEdges()->getEdges();
		for(int i=0;i<(int)ees->size();i++) {
			DirectedEdge *de=(DirectedEdge*) (*ees)[i];
			DirectedEdge *sym=de->getSym();
			if (sym->isVisited()) continue;
			Node *adjNode=sym->getNode();

			if (! contains(&nodesVisited,adjNode))
			{
				nodeQueue.push_back(adjNode);
				nodesVisited.push_back(adjNode);
			}
		}
	}
}

bool BufferSubgraph::contains(vector<Node*> *nodes,Node *node) {
	bool result=false;
	for(int i=0;i<(int)nodes->size();i++) {
		if (node==(*nodes)[i]) {
			result=true;
			break;
		}
	}
	return result;
}

Envelope *
BufferSubgraph::getEnvelope()
{
	if (env == NULL) {
		env = new Envelope();
		unsigned int size = dirEdgeList->size();
		for(unsigned int i=0; i<size; ++i)
		{
			DirectedEdge *dirEdge=(*dirEdgeList)[i];
			const CoordinateSequence *pts = dirEdge->getEdge()->getCoordinates();
			int n = pts->getSize()-1;
			for (int j=0; j<n; ++j) {
				env->expandToInclude(pts->getAt(j));
			}
		}
	}
	return env;
}

} // namespace geos

/**********************************************************************
 * $Log: BufferSubgraph.cpp,v $
 * Revision 1.12.2.1  2005/06/30 18:31:21  strk
 * Ported SubgraphDepthLocator optimizations from JTS code
 *
 * Revision 1.12  2004/12/08 13:54:43  strk
 * gcc warnings checked and fixed, general cleanups.
 *
 * Revision 1.11  2004/07/07 07:52:13  strk
 * Removed note about required speedup in BufferSubgraph.
 * I've made tests with 'sets' and there is actually a big slow down..
 *
 * Revision 1.10  2004/07/02 13:28:27  strk
 * Fixed all #include lines to reflect headers layout change.
 * Added client application build tips in README.
 *
 * Revision 1.9  2004/05/19 12:50:53  strk
 * Removed all try/catch blocks transforming stack allocated-vectors to auto-heap-allocations
 *
 * Revision 1.8  2004/05/03 22:56:44  strk
 * leaks fixed, exception specification omitted.
 *
 * Revision 1.7  2004/05/03 17:15:38  strk
 * leaks on exception fixed.
 *
 * Revision 1.6  2004/04/16 12:48:07  strk
 * Leak fixes.
 *
 * Revision 1.5  2004/04/10 08:40:01  ybychkov
 * "operation/buffer" upgraded to JTS 1.4
 *
 *
 **********************************************************************/