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/** \file Observer.hh
 *
 * This file contains an observer class which is used to monitor the progress
 * of an decimater.
 *
 */

//=============================================================================
//
//  CLASS Observer
//
//=============================================================================

#pragma once

//== INCLUDES =================================================================

#include <cstddef>
#include <OpenMesh/Core/System/config.h>

//== NAMESPACE ================================================================

namespace OpenMesh  {
namespace Decimater {


//== CLASS DEFINITION =========================================================

/** \brief Observer class
 *
 * Observers can be used to monitor the progress of the decimation and to
 * abort it in between.
 */
class OPENMESHDLLEXPORT Observer
{
public:

  /** Create an observer
   *
   * @param _notificationInterval Interval of decimation steps between notifications.
   */
  explicit Observer(size_t _notificationInterval);
  
  /// Destructor
  virtual ~Observer();
  
  /// Get the interval between notification steps
  size_t get_interval() const;

  /// Set the interval between notification steps
  void set_interval(size_t _notificationInterval);
  
  /** \brief callback
   *
   * This function has to be overloaded. It will be called regularly during
   * the decimation process and will return the current step.
   *
   * @param _step Current step of the decimater
   */
  virtual void notify(size_t _step) = 0;

  /** \brief Abort callback
   *
   * After each notification, this function is called by the decimater. If the
   * function returns true, the decimater will stop at a consistent state. Otherwise
   * it will continue.
   *
   * @return abort Yes or No
   */
  virtual bool abort() const;
  
private:
  size_t notificationInterval_;
};


//=============================================================================
} // END_NS_DECIMATER
} // END_NS_OPENMESH
//=============================================================================
