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

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


Copyright (c) 1993-1998 Ken Martin, Will Schroeder, Bill Lorensen.

This software is copyrighted by Ken Martin, Will Schroeder and Bill Lorensen.
The following terms apply to all files associated with the software unless
explicitly disclaimed in individual files. This copyright specifically does
not apply to the related textbook "The Visualization Toolkit" ISBN
013199837-4 published by Prentice Hall which is covered by its own copyright.

The authors hereby grant permission to use, copy, and distribute this
software and its documentation for any purpose, provided that existing
copyright notices are retained in all copies and that this notice is included
verbatim in any distributions. Additionally, the authors grant permission to
modify this software and its documentation for any purpose, provided that
such modifications are not distributed without the explicit consent of the
authors and that existing copyright notices are retained in all copies. Some
of the algorithms implemented by this software are patented, observe all
applicable patent law.

IN NO EVENT SHALL THE AUTHORS OR DISTRIBUTORS BE LIABLE TO ANY PARTY FOR
DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT
OF THE USE OF THIS SOFTWARE, ITS DOCUMENTATION, OR ANY DERIVATIVES THEREOF,
EVEN IF THE AUTHORS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

THE AUTHORS AND DISTRIBUTORS SPECIFICALLY DISCLAIM ANY WARRANTIES, INCLUDING,
BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
PARTICULAR PURPOSE, AND NON-INFRINGEMENT.  THIS SOFTWARE IS PROVIDED ON AN
"AS IS" BASIS, AND THE AUTHORS AND DISTRIBUTORS HAVE NO OBLIGATION TO PROVIDE
MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.


=========================================================================*/
// .NAME vtkCellLinks - object represents upward pointers from points to list of cells using each point
// .SECTION Description
// vtkCellLinks is a supplemental object to vtkCellArray and vtkCellTypes, 
// enabling access from points to the cells using the points. vtkCellLinks is
// a list of Links, each link represents a dynamic list of cell id's using the 
// point. The information provided by this object can be used to determine 
// neighbors and construct other local topological information.
// .SECTION See Also
// vtkCellArray vtkCellTypes

#ifndef __vtkCellLinks_h
#define __vtkCellLinks_h

#include "vtkObject.h"
class vtkDataSet;

struct _vtkLink_s {
    unsigned short ncells;
    int *cells;
};

class VTK_EXPORT vtkCellLinks : public vtkObject 
{
public:
  vtkCellLinks():Array(NULL),Size(0),MaxId(-1),Extend(1000) {};
  vtkCellLinks(int sz, int ext=1000);
  ~vtkCellLinks();
  static vtkCellLinks *New() {return new vtkCellLinks;};
  const char *GetClassName() {return "vtkCellLinks";};

  // Description:
  // Get a link structure given a point id.
  _vtkLink_s &GetLink(int ptId) {return this->Array[ptId];};

  // Description:
  // Get the number of cells using the point specified by ptId.
  unsigned short GetNcells(int ptId) { return this->Array[ptId].ncells;};

  // Description:
  // Build the link list array.
  void BuildLinks(vtkDataSet *data);

  // Description:
  // Return a list of cell ids using the point.
  int *GetCells(int ptId) {return this->Array[ptId].cells;};

  // Description:
  // Insert a new point into the cell-links data structure. The size parameter
  // is the initial size of the list.
  int InsertNextPoint(int numLinks);

  // Description:
  // Insert a cell id into the list of cells (at the end) using the cell id 
  // provided. (Make sure to extend the link list (if necessary) using the
  // method ResizeCellList().)
  void InsertNextCellReference(int ptId, int cellId);

  // Description:
  // Delete point (and storage) by destroying links to using cells.
  void DeletePoint(int ptId);

  // Description:
  // Delete the reference to the cell (cellId) from the point (ptId). This
  // removes the reference to the cellId from the cell list, but does not
  // resize the list (recover memory with ResizeCellList(), if necessary).
  void RemoveCellReference(int cellId, int ptId);

  // Description:
  // Add the reference to the cell (cellId) from the point (ptId). This
  // adds a reference to the cellId from the cell list, but does not resize
  // the list (extend memory with ResizeCellList(), if necessary).
  void AddCellReference(int cellId, int ptId);

  // Description:
  // Change the length of a point's link list (i.e., list of cells using a
  // point) by the size specified.
  void ResizeCellList(int ptId, int size);

  // Description:
  // Reclaim any unused memory.
  void Squeeze();

  // Description:
  // Reset to a state of no entries without freeing the memory.
  void Reset();

private:
  // Description:
  // Increment the count of the number of cells using the point.
  void IncrementLinkCount(int ptId) { this->Array[ptId].ncells++;};

  void AllocateLinks(int n);

  // Description:
  // Insert a cell id into the list of cells using the point.
  void InsertCellReference(int ptId, unsigned short pos, int cellId);

  _vtkLink_s *Array;   // pointer to data
  int Size;       // allocated size of data
  int MaxId;     // maximum index inserted thus far
  int Extend;     // grow array by this point
  _vtkLink_s *Resize(int sz);  // function to resize data
};


inline void vtkCellLinks::InsertCellReference(int ptId, unsigned short pos, int cellId) 
{
  this->Array[ptId].cells[pos] = cellId;
}

inline void vtkCellLinks::DeletePoint(int ptId)
{
  this->Array[ptId].ncells = 0;
  delete [] this->Array[ptId].cells;
  this->Array[ptId].cells = NULL;
}

inline void vtkCellLinks::InsertNextCellReference(int ptId, int cellId) 
{
  this->Array[ptId].cells[this->Array[ptId].ncells++] = cellId;
}

inline void vtkCellLinks::RemoveCellReference(int cellId, int ptId)
{
  int *cells=this->Array[ptId].cells;
  int ncells=this->Array[ptId].ncells;

  for (int i=0; i < ncells; i++)
    {
    if (cells[i] == cellId)
      {
      for (int j=i; j < (ncells-1); j++)
	{
	cells[j] = cells[j+1];
	}
      this->Array[ptId].ncells--;
      break;
      }
    }
}

inline void vtkCellLinks::AddCellReference(int cellId, int ptId)
{
  this->Array[ptId].cells[this->Array[ptId].ncells++] = cellId;
}

inline void vtkCellLinks::ResizeCellList(int ptId, int size)
{
  int *cells, newSize;

  newSize = this->Array[ptId].ncells + size;
  cells = new int[newSize];
  memcpy(cells, this->Array[ptId].cells, this->Array[ptId].ncells*sizeof(int));
  delete [] this->Array[ptId].cells;
  this->Array[ptId].cells = cells;
}

#endif

