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

  Program:   Visualization Toolkit
  Module:    vtkEdgeLayout.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.

=========================================================================*/
/*----------------------------------------------------------------------------
 Copyright (c) Sandia Corporation
 See Copyright.txt or http://www.paraview.org/HTML/Copyright.html for details.
----------------------------------------------------------------------------*/
// .NAME vtkEdgeLayout - layout graph edges
//
// .SECTION Description
// This class is a shell for many edge layout strategies which may be set
// using the SetLayoutStrategy() function.  The layout strategies do the
// actual work.

#ifndef __vtkEdgeLayout_h
#define __vtkEdgeLayout_h

#include "vtkGraphAlgorithm.h"

class vtkEdgeLayoutStrategy;
class vtkEventForwarderCommand;

class VTK_INFOVIS_EXPORT vtkEdgeLayout : public vtkGraphAlgorithm 
{
public:
  static vtkEdgeLayout *New();
  vtkTypeRevisionMacro(vtkEdgeLayout, vtkGraphAlgorithm);
  void PrintSelf(ostream& os, vtkIndent indent);

  // Description:
  // The layout strategy to use during graph layout.
  void SetLayoutStrategy(vtkEdgeLayoutStrategy *strategy);
  vtkGetObjectMacro(LayoutStrategy, vtkEdgeLayoutStrategy);
  
  // Description:
  // Get the modification time of the layout algorithm.
  virtual unsigned long GetMTime();

protected:
  vtkEdgeLayout();
  ~vtkEdgeLayout();

  vtkEdgeLayoutStrategy* LayoutStrategy;

  // Description:
  // This intercepts events from the strategy object and re-emits them
  // as if they came from the layout engine itself.
  vtkEventForwarderCommand *EventForwarder;
  unsigned long ObserverTag;

  int RequestData(
    vtkInformation *, 
    vtkInformationVector **, 
    vtkInformationVector *);
  
private:

  vtkGraph *InternalGraph;
  bool StrategyChanged;

  vtkEdgeLayout(const vtkEdgeLayout&);  // Not implemented.
  void operator=(const vtkEdgeLayout&);  // Not implemented.
};

#endif
