/*=========================================================================

  Program:   Visualization Toolkit
  Module:    vtkEdgeTable.h
  Language:  C++
  Date:      $Date$
  Version:   $Revision$


Copyright (c) 1993-2000 Ken Martin, Will Schroeder, Bill Lorensen 
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=========================================================================*/
// .NAME vtkEdgeTable - keep track of edges (edge is pair of integer id's)
// .SECTION Description
// vtkEdgeTable is a general object for keeping track of lists of edges. An
// edge is defined by the pair of point id's (p1,p2). Methods are available
// to insert edges, check if edges exist, and traverse the list of edges.
// Also, it's possible to associate attribute information with each edge.

#ifndef __vtkEdgeTable_h
#define __vtkEdgeTable_h

#include "vtkObject.h"

class vtkIdList;
class vtkPoints;

class VTK_EXPORT vtkEdgeTable : public vtkObject
{
public:
  // Description:
  // Instantiate object assuming that 1000 edges are to be inserted.
  static vtkEdgeTable *New();

  vtkTypeMacro(vtkEdgeTable,vtkObject);
  void PrintSelf(ostream& os, vtkIndent indent);

  // Description:
  // Free memory and return to instantiated state.
  void Initialize();

  // Description:
  // Initialize the edge insertion process. Provide an estimate of the
  // number of points in a dataset (the maximum range value of p1 or
  // p2).  The storeAttributes variable controls whether attributes
  // are to be stored with the edge. If on, additional memory will be
  // required by the data structure to store an integer id per each
  // edge.  This method is used in conjunction with one of the two
  // InsertEdge() methods described below (don't mix the InsertEdge()
  // methods). 
  int InitEdgeInsertion(int numPoints, int storeAttributes=0);

  // Description:
  // Insert the edge (p1,p2) into the table. It is the user's
  // responsibility to check if the edge has already been inserted
  // (use IsEdge()). If the storAttributes flag in InitEdgeInsertion()
  // has been set, then the method returns a unique integer id (i.e.,
  // the edge id) that can be used to set and get edge
  // attributes. Otherwise, the method will return 1. Do not mix this
  // method with the InsertEdge() method that follows.
  int InsertEdge(int p1, int p2);

  // Description:
  // Insert the edge (p1,p2) into the table with the attribute id
  // specified (make sure the attributeId >= 0). Note that the
  // attributeId is ignored if the storeAttributes variable was set to
  // 0 in the InitEdgeInsertion() method. It is the user's
  // responsibility to check if the edge has already been inserted
  // (use IsEdge()). Do not mix this method with the previous
  // InsertEdge() method.
  void InsertEdge(int p1, int p2, int attributeId);

  // Description: 
  // Return an integer id for the edge, or an attributeId of the edge
  // (p1,p2) if the edge has been previously defined (it depends upon
  // which version of InsertEdge() is being used); otherwise -1. The
  // unique integer id can be used to set and retrieve attributes to
  // the edge.
  int IsEdge(int p1, int p2);

  // Description:
  // Initialize the point insertion process. The newPts is an object
  // representing point coordinates into which incremental insertion methods
  // place their data. The points are associated with the edge.
  int InitPointInsertion(vtkPoints *newPts, int estSize);

  // Description:
  // Insert a unique point on the specified edge. Invoke this method only
  // after InitPointInsertion() has been called. Return 0 if point was 
  // already in the list, otherwise return 1.
  int InsertUniquePoint(int p1, int p2, float x[3], int &ptId);

  // Description:
  // Return the number of edges that have been inserted thus far.
  vtkGetMacro(NumberOfEdges, int);

  // Description:
  // Intialize traversal of edges in table.
  void InitTraversal();

  // Description:
  // Traverse list of edges in table. Return the edge as (p1,p2), where p1
  // and p2 are point id's. Method return value is zero if list is exhausted;
  // non-zero otherwise. The value of p1 is guaranteed to be <= p2.
  int GetNextEdge(int &p1, int &p2);

  // Description:
  // Reset the object and prepare for reinsertion of edges. Does not delete
  // memory like the Initialize() method.
  void Reset();

protected:
  vtkEdgeTable();
  ~vtkEdgeTable();
  vtkEdgeTable(const vtkEdgeTable&) {};
  void operator=(const vtkEdgeTable&) {};

  vtkIdList **Table;
  vtkIdList **Attributes;
  int StoreAttributes;
  int TableMaxId; //maximum point id inserted
  int TableSize;  //allocated size of table
  int Position[2];
  int Extend;
  int NumberOfEdges;
  vtkPoints *Points; //support point insertion

  vtkIdList **Resize(int size);
};

#endif

