text: /*=========================================================================
  
    Program:   Visualization Toolkit
    Module:    vtkGraphWeightFilter.h
  
    Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
    All rights reserved.
    See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
  
       This software is distributed WITHOUT ANY WARRANTY; without even
       the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
       PURPOSE.  See the above copyright notice for more information.
  
  =========================================================================*/
  /**
   * @class   vtkGraphWeightFilter
   * @brief   Base class for filters that weight graph
   * edges.
   *
   *
   * vtkGraphWeightFilter is the abstract base class that provides an interface
   * for classes that apply weights to graph edges. The weights are added
   * as a vtkFloatArray named "Weights."
   * The ComputeWeight function must be implemented to provide the function of two
   * vertices which determines the weight of each edge.
   * The CheckRequirements function can be implemented if you wish to ensure
   * that the input graph has all of the properties that will be required
   * by the ComputeWeight function.
  */
  
  #ifndef vtkGraphWeightFilter_h
  #define vtkGraphWeightFilter_h
  
  #include "vtkFiltersGeneralModule.h" // For export macro
  #include "vtkGraphAlgorithm.h"
  
  class vtkGraph;
  
  class VTKFILTERSGENERAL_EXPORT vtkGraphWeightFilter : public vtkGraphAlgorithm
  {
  public:
    vtkTypeMacro(vtkGraphWeightFilter, vtkGraphAlgorithm);
    void PrintSelf(ostream& os, vtkIndent indent) VTK_OVERRIDE;
  
  protected:
    vtkGraphWeightFilter(){}
    ~vtkGraphWeightFilter() VTK_OVERRIDE {}
  
    int RequestData(vtkInformation *,
                    vtkInformationVector **,
                    vtkInformationVector *) VTK_OVERRIDE;
  
    /**
     * Compute the weight on the 'graph' for a particular 'edge'.
     * This is a pure virtual function that must be implemented in subclasses.
     */
    virtual float ComputeWeight(vtkGraph* const graph, const vtkEdgeType& edge) const = 0;
  
    /**
     * Ensure that the 'graph' is has all properties that are needed to compute
     * the weights. For example, in vtkGraphWeightEuclideanDistanceFilter,
     * 'graph' must have Points set for each vertex, as the ComputeWeight
     * function calls GetPoint.
     */
    virtual bool CheckRequirements(vtkGraph* const graph) const;
  
  private:
    vtkGraphWeightFilter(const vtkGraphWeightFilter&) VTK_DELETE_FUNCTION;
    void operator=(const vtkGraphWeightFilter&) VTK_DELETE_FUNCTION;
  };
  
  #endif
  