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#ifndef GRID_H

#define GRID_H

#include <QtCore>

#include <stdexcept>

/** Grid class (template).

  */

template <class T>

class Grid {

public:

    Grid();

    Grid(int cellsize, int sizex, int sizey) { mData=0; setup(cellsize, sizex, sizey); }

    // copy ctor

    Grid(const Grid<T>& toCopy);

    ~Grid() { if (mData) delete[] mData; }

    bool setup(const float cellsize, const int sizex, const int sizey);

    bool setup(const QRectF& rect, const double cellsize);

    void initialize(const T& value) {for( T *p = begin();p!=end(); ++p) *p=value;}

    const int sizeX() const { return mSizeX; }

    const int sizeY() const { return mSizeY; }

    const float metricSizeX() const { return mSizeX*mCellsize; }

    const float metricSizeY() const { return mSizeY*mCellsize; }

    const float cellsize() const { return mCellsize; }

    const int count() const { return mCount; }

    // operations

    // query

    /// access (const) with index variables. use int.

    inline const T& operator()(const int ix, const int iy) const { return constValueAtIndex(ix, iy); }

    /// access (const) using metric variables. use float.

    inline const T& operator()(const float x, const float y) const { return constValueAt(x, y); }

    T& valueAtIndex(const QPoint& pos); ///< value at position defined by indices (x,y)

    T& valueAtIndex(const int ix, const int iy) { return valueAtIndex(QPoint(ix,iy)); } ///< const value at position defined by indices (x,y)

    const T& constValueAtIndex(const QPoint& pos) const; ///< value at position defined by a (integer) QPoint

    const T& constValueAtIndex(const int ix, const int iy) const { return constValueAtIndex(QPoint(ix,iy)); }

    T& valueAt(const QPointF& posf); ///< value at position defined by metric coordinates (QPointF)

    const T& constValueAt(const QPointF& posf) const; ///< value at position defined by metric coordinates (QPointF)

    T& valueAt(const float x, const float y); ///< value at position defined by metric coordinates (x,y)

    const T& constValueAt(const float x, const float y) const; ///< value at position defined by metric coordinates (x,y)

    QPoint indexAt(const QPointF& pos) const { return QPoint(int((pos.x()-mOffset.x()) / mCellsize),  int((pos.y()-mOffset.y())/mCellsize)); } /// get index of value at position pos (metric)

    bool isIndexValid(const QPoint& pos) const { return (pos.x()>=0 && pos.x()<mSizeX && pos.y()>=0 && pos.y()<mSizeY); } /// get index of value at position pos (index)

    void validate(QPoint &pos) const{ pos.setX( qMax(qMin(pos.x(), mSizeX-1), 0) );  pos.setY( qMax(qMin(pos.y(), mSizeY-1), 0) );} /// ensure that "pos" is a valid key. if out of range, pos is set to minimum/maximum values.

    QPointF cellCoordinates(const QPoint &pos) { return QPointF( (pos.x()+0.5)*mCellsize+mOffset.x(), (pos.y()+0.5)*mCellsize + mOffset.y());} /// get metric coordinates of the cells center

    inline  T* begin() const { return mData; } ///< get "iterator" pointer

    inline  T* end() const { return &(mData[mCount]); } ///< get iterator end-pointer

    QPoint indexOf(T* element) const; ///< retrieve index (x/y) of the pointer element. returns -1/-1 if element is not valid.

    // special queries

    T max() const; ///< retrieve the maximum value of a grid

    T sum() const; ///< retrieve the sum of the grid

    T avg() const; ///< retrieve the average value of a grid

    /// creates a grid with lower resolution and averaged cell values.

    /// @param factor factor by which grid size is reduced (e.g. 3 -> 3x3=9 pixels are averaged to 1 result pixel)

    /// @param offsetx, offsety: start averaging with an offset from 0/0 (e.g.: x=1, y=2, factor=3: -> 1/2-3/4 -> 0/0)

    /// @return Grid with size sizeX()/factor x sizeY()/factor

    Grid<T> averaged(const int factor, const int offsetx=0, const int offsety=0) const;

    /// normalized returns a normalized grid, in a way that the sum()  = @param targetvalue.

    /// if the grid is empty or the sum is 0, no modifications are performed.

    Grid<T> normalized(const T targetvalue) const;

private:

    T* mData;

    QPointF mOffset;

    float mCellsize; ///< size of a cell in meter

    int mSizeX; ///< count of cells in x-direction

    int mSizeY; ///< count of cells in y-direction

    int mCount; ///< total number of cells in the grid

};

typedef Grid<float> FloatGrid;

// copy constructor

template <class T>

Grid<T>::Grid(const Grid<T>& toCopy)

{

    setup(toCopy.cellsize(), toCopy.sizeX(), toCopy.sizeY());

    const T* end = toCopy.end();

    T* ptr = begin();

    for (T* i= toCopy.begin(); i!=end; ++i, ++ptr)

       *ptr = *i;

}

// normalize function

template <class T>

Grid<T> Grid<T>::normalized(const T targetvalue) const

{

    Grid<T> target(*this);

    T total = sum();

    T multiplier;

    if (total)

        multiplier = targetvalue / total;

    else

        return target;

    for (T* p=target.begin();p!=target.end();++p)

        *p *= multiplier;

}

template <class T>

Grid<T> Grid<T>::averaged(const int factor, const int offsetx, const int offsety) const

{

    Grid<T> target;

    target.setup(cellsize()*factor, sizeX()/factor, sizeY()/factor);

    int x,y;

    T sum=0;

    target.initialize(sum);

    // sum over array of 2x2, 3x3, 4x4, ...

    for (x=offsetx;x<mSizeX;x++)

        for (y=offsety;y<mSizeY;y++) {

            target.valueAtIndex((x-offsetx)/factor, (y-offsety)/factor) += constValueAtIndex(x,y);

        }

    // divide

    double fsquare = factor*factor;

    for (T* p=target.begin();p!=target.end();++p)

        *p /= fsquare;

    return target;

}

template <class T>

T&  Grid<T>::valueAtIndex(const QPoint& pos)

{

    if (isIndexValid(pos)) {

        return mData[pos.x()*mSizeX + pos.y()];

    }

    throw std::logic_error("TGrid: invalid Index!");

}

template <class T>

const T&  Grid<T>::constValueAtIndex(const QPoint& pos) const

{

    if (isIndexValid(pos)) {

        return mData[pos.x()*mSizeX + pos.y()];

    }

    throw std::logic_error("TGrid: invalid Index!");

}

template <class T>

T&  Grid<T>::valueAt(const float x, const float y)

{

    return valueAtIndex( indexAt(QPointF(x,y)) );

}

template <class T>

const T&  Grid<T>::constValueAt(const float x, const float y) const

{

    return constValueAtIndex( indexAt(QPointF(x,y)) );

}

template <class T>

T&  Grid<T>::valueAt(const QPointF& posf)

{

    return valueAtIndex( indexAt(posf) );

}

template <class T>

const T&  Grid<T>::constValueAt(const QPointF& posf) const

{

    return constValueAtIndex( indexAt(posf) );

}

template <class T>

Grid<T>::Grid()

{

    mData=0; mCellsize=0.f;

}

template <class T>

bool Grid<T>::setup(const float cellsize, const int sizex, const int sizey)

{

    mSizeX=sizex; mSizeY=sizey; mCellsize=(float)cellsize;

    mCount = mSizeX*mSizeY;

    if (mData)

         delete[] mData;

   if (mCount>0)

    mData = new T[mCount];

   return true;

}

template <class T>

bool Grid<T>::setup(const QRectF& rect, const double cellsize)

{

    mOffset.setX(rect.left());

    mOffset.setY(rect.top());

    int dx = int(rect.width()/cellsize);

    if (mOffset.x()+cellsize*dx<rect.right())

        dx++;

    int dy = int(rect.height()/cellsize);

    if (mOffset.y()+cellsize*dy<rect.bottom())

        dy++;

    return setup(cellsize, dx, dy);

}

template <class T>

QPoint Grid<T>::indexOf(T* element) const

{

    QPoint result(-1,-1);

    if (element==NULL || element<mData || element>=end())

        return result;

    int idx = element - mData;

    result.setX( idx / mSizeX);

    result.setY( idx % mSizeX);

    return result;

}

template <class T>

T  Grid<T>::max() const

{

    T maxv = std::numeric_limits<T>::min();

    T* p;

    T* pend = end();

    for (p=begin(); p!=pend;++p)

       maxv = std::max(maxv, *p);

    return maxv;

}

template <class T>

T  Grid<T>::sum() const

{

    T* pend = end();

    T total = 0;

    for (T *p=begin(); p!=pend;++p)

       total += *p;

    return total;

}

template <class T>

T  Grid<T>::avg() const

{

    if (count())

        return sum() / T(count());

    else return 0;

}

////////////////////////////////////////////////////////////7

// global functions

////////////////////////////////////////////////////////////7

/// dumps a FloatGrid to a String.

/// rows will be y-lines, columns x-values.

QString gridToString(const FloatGrid &grid);

/// creates and return a QImage from Grid-Data.

/// @param black_white true: max_value = white, min_value = black, false: color-mode: uses a HSV-color model from blue (min_value) to red (max_value), default: color mode (false)

/// @param min_value, max_value min/max bounds for color calcuations. values outside bounds are limited to these values. defaults: min=0, max=1

/// @param reverse if true, color ramps are inversed (to: min_value = white (black and white mode) or red (color mode). default = false.

/// @return a QImage with the Grids size of pixels. Pixel coordinates relate to the index values of the grid.

QImage gridToImage(const FloatGrid &grid,

                   bool black_white=false,

                   double min_value=0., double max_value=1.,

                   bool reverse=false);

/// template version for non-float grids.

template <class T>

QString gridToString(const Grid<T> &grid)

{

    QString res;

    QTextStream ts(&res);

    for (int x=0;x<grid.sizeX();x++){

        for (int y=0;y<grid.sizeY();y++) {

            ts << grid.constValueAtIndex(x,y) << ";";

        }

        ts << "\r\n";

    }

    return res;

}

#endif // GRID_H