/***************************************************************************
                          qgsaspectfilter.h  -  description
                          ---------------------------------
    begin                : August 7th, 2009
    copyright            : (C) 2009 by Marco Hugentobler
    email                : marco dot hugentobler at karto dot baug dot ethz dot ch
 ***************************************************************************/

/***************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/

#ifndef QGSASPECTFILTER_H
#define QGSASPECTFILTER_H

#include "qgsderivativefilter.h"

/**Calculates aspect values in a window of 3x3 cells based on first order derivatives in x- and y- directions. Direction is clockwise starting from north*/
class ANALYSIS_EXPORT QgsAspectFilter: public QgsDerivativeFilter
{
  public:
    QgsAspectFilter( const QString& inputFile, const QString& outputFile, const QString& outputFormat );
    ~QgsAspectFilter();

  protected:
  protected:
    /**Calculates output value from nine input values. The input values and the output value can be equal to the \
      nodata value if not present or outside of the border. Must be implemented by subclasses*/
    float processNineCellWindow( float* x11, float* x21, float* x31, \
                                 float* x12, float* x22, float* x32, float* x13, float* x23, float* x33 );
};

#endif // QGSASPECTFILTER_H
