qgsinterpolator.h

/***************************************************************************
                              qgsinterpolator.h
                              ------------------------
  begin                : March 10, 2008
  copyright            : (C) 2008 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 QGSINTERPOLATOR_H
#define QGSINTERPOLATOR_H

#include <QVector>
#include "qgis_analysis.h"

class QgsVectorLayer;
class QgsGeometry;

struct ANALYSIS_EXPORT vertexData
{
  double x;
  double y;
  double z;
};

/** \ingroup analysis
 * Interface class for interpolations. Interpolators take
the vertices of a vector layer as base data. The z-Value
can be an attribute or the z-coordinates in case of 25D types*/
class ANALYSIS_EXPORT QgsInterpolator
{
  public:
    //! Describes the type of input data
    enum InputType
    {
      POINTS,
      STRUCTURE_LINES,
      BREAK_LINES
    };

    //! A layer together with the information about interpolation attribute / z-coordinate interpolation and the type (point, structure line, breakline)
    struct LayerData
    {
      QgsVectorLayer *vectorLayer = nullptr;
      bool zCoordInterpolation;
      int interpolationAttribute;
      InputType mInputType;
    };

    QgsInterpolator( const QList<LayerData> &layerData );

    virtual ~QgsInterpolator() = default;

    /** Calculates interpolation value for map coordinates x, y
       \param x x-coordinate (in map units)
       \param y y-coordinate (in map units)
       \param result out: interpolation result
       \return 0 in case of success*/
    virtual int interpolatePoint( double x, double y, double &result ) = 0;

    //! \note not available in Python bindings
    QList<LayerData> layerData() const { return mLayerData; }

  protected:

    /** Caches the vertex and value data from the provider. All the vertex data
     will be held in virtual memory
    \return 0 in case of success*/
    int cacheBaseData();

    QVector<vertexData> mCachedBaseData;

    //! Flag that tells if the cache already has been filled
    bool mDataIsCached;

    //Information about the input vector layers and the attributes (or z-values) that are used for interpolation
    QList<LayerData> mLayerData;

  private:
    QgsInterpolator(); //forbidden

    /** Helper method that adds the vertices of a geometry to the mCachedBaseData
       \param geom the geometry
       \param zCoord true if the z-coordinate of the geometry is to be interpolated
       \param attributeValue the attribute value for interpolation (if not interpolated from z-coordinate)
     \return 0 in case of success*/
    int addVerticesToCache( const QgsGeometry &geom, bool zCoord, double attributeValue );
};

#endif