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

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


Copyright (c) 1993-2000 Ken Martin, Will Schroeder, Bill Lorensen 
All rights reserved.

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 * Neither name of Ken Martin, Will Schroeder, or Bill Lorensen nor the names
   of any contributors may be used to endorse or promote products derived
   from this software without specific prior written permission.

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   misrepresented as being the original software.

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=========================================================================*/
// .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;
class vtkCellArray;

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

class VTK_EXPORT vtkCellLinks : public vtkObject 
{
public:
  static vtkCellLinks *New();
  vtkTypeMacro(vtkCellLinks,vtkObject);

  // Description:
  // Allocate the specified number of links (i.e., number of points) that
  // will be built.
  void Allocate(int numLinks, int ext=1000);

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

  // 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();

  // Description:
  // Return the memory in kilobytes consumed by this cell links array. 
  // Used to support streaming and reading/writing data. The value 
  // returned is guaranteed to be greater than or equal to the memory 
  // required to actually represent the data represented by this object. 
  // The information returned is valid only after the pipeline has 
  // been updated.
  unsigned long GetActualMemorySize();
  
protected:
  vtkCellLinks():Array(NULL),Size(0),MaxId(-1),Extend(1000) {};
  ~vtkCellLinks();
  vtkCellLinks(const vtkCellLinks&) {};
  void operator=(const vtkCellLinks&) {};

  // 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

