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#ifndef GRID_H

#define GRID_H

#include <QtCore>

#include <stdexcept>

#include <limits>

#include <cstring>

#include "global.h"

/** Grid class (template).

Orientation

The grid is oriented as typically coordinates on the northern hemisphere: greater y-values -> north, greater x-values-> east.

The projection is reversed for drawing on screen (Viewport):

          N

  (2/0) (2/1) (2/2)

E (1/0) (1/1) (2/1)  W

  (0/0) (1/0) (2/0)

          S

*/

template <class T>

class Grid {

public:

    Grid();

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

    Grid(const QRectF rect_metric, const float cellsize) { mData=0; setup(rect_metric,cellsize); }

    // copy ctor

    Grid(const Grid<T>& toCopy);

    ~Grid() { clear(); }

    void clear() { if (mData) delete[] mData; mData=0; }

    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; }

    void wipe(); ///< write 0-bytes with memcpy to the whole area

    void wipe(const T value); ///< overwrite the whole area with "value" size of T must be the size of "int" ERRORNOUS!!!

    int sizeX() const { return mSizeX; }

    int sizeY() const { return mSizeY; }

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

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

    QRectF metricRect() const { return mRect; }

    float cellsize() const { return mCellsize; }

    int count() const { return mCount; } ///< returns the number of elements of the grid

    bool isEmpty() const { return mData==NULL; } ///< returns false if the grid was not setup

    // 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); }

    inline const T& operator[] (const QPointF &p) const { return constValueAt(p); }

    inline 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)

    T& valueAtIndex(const int index) {return mData[index]; } ///< get a ref ot value at (one-dimensional) index 'index'.

    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)

    bool coordValid(const float x, const float y) const { return x>=mRect.left() && x<mRect.right()  && y>=mRect.top() && y<mRect.bottom(); }

    bool coordValid(const QPointF &pos) const { return coordValid(pos.x(), pos.y()); }

    QPoint indexAt(const QPointF& pos) const { return QPoint(int((pos.x()-mRect.left()) / mCellsize),  int((pos.y()-mRect.top())/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); } ///< return true, if position is within the grid

    bool isIndexValid(const int x, const int y) const {return (x>=0 && x<mSizeX && y>=0 && y<mSizeY); } ///< return true, if index is within the grid

    /// force @param pos to contain valid indices with respect to this grid.

    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.

    /// get the (metric) centerpoint of cell with index @p pos

    QPointF cellCenterPoint(const QPoint &pos) { return QPointF( (pos.x()+0.5)*mCellsize+mRect.left(), (pos.y()+0.5)*mCellsize + mRect.top());} ///< get metric coordinates of the cells center

    /// get the metric rectangle of the cell with index @pos

    QRectF cellRect(const QPoint &pos) const { QRectF r( QPointF(mRect.left() + mCellsize*pos.x(), mRect.top() + pos.y()*mCellsize),

                                                   QSizeF(mCellsize, mCellsize)); return r; } ///< return coordinates of rect given by @param pos.

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

    inline  T* end() const { return mEnd; } ///< 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

    // modifying operations

    void add(const T& summand);

    void multiply(const T& factor);

    /// 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;

    T* ptr(int x, int y) { return &(mData[y*mSizeX + x]); } ///< get a pointer to the element denoted by "x" and "y"

    inline double distance(const QPoint &p1, const QPoint &p2); ///< distance (metric) between p1 and p2

    const QPoint randomPosition() const; ///< returns a (valid) random position within the grid

private:

    T* mData;

    T* mEnd; ///< pointer to 1 element behind the last

    QRectF mRect;

    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;

/** @class GridRunner is a helper class to iterate over a rectangular fraction of a grid

*/

template <class T>

class GridRunner {

public:

    GridRunner(Grid<T> &target_grid, const QRectF &rectangle) {setup(target_grid, rectangle);}

    GridRunner(const Grid<T> &target_grid, const QRectF &rectangle) {setup(target_grid, rectangle);}

    T* next(); ///< to to next element, return NULL if finished

private:

    void setup(const Grid<T> &target_grid, const QRectF &rectangle);

    T* mLast;

    T* mCurrent;

    size_t mLineLength;

    size_t mCols;

    size_t mCurrentCol;

};

// copy constructor

template <class T>

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

{

    mData = 0;

    mRect = toCopy.mRect;

    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;

    return target;

}

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.y()*mSizeX + pos.x()];

    //}

    //qCritical("Grid::valueAtIndex. invalid: %d/%d", pos.x(), pos.y());

    //return mData[0];

}

template <class T>

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

{

    //if (isIndexValid(pos)) {

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

    //}

    //qCritical("Grid::constValueAtIndex. invalid: %d/%d", pos.x(), pos.y());

    //return mData[0];

}

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;

    mEnd = 0;

}

template <class T>

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

{

    mSizeX=sizex; mSizeY=sizey; mCellsize=cellsize;

    if (mRect.isNull()) // only set rect if not set before

        mRect.setCoords(0., 0., cellsize*sizex, cellsize*sizey);

    mCount = mSizeX*mSizeY;

    if (mData) {

         delete[] mData; mData=NULL;

     }

   if (mCount>0)

        mData = new T[mCount];

   mEnd = &(mData[mCount]);

   return true;

}

template <class T>

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

{

    mRect = rect;

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

    if (mRect.left()+cellsize*dx<rect.right())

        dx++;

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

    if (mRect.top()+cellsize*dy<rect.bottom())

        dy++;

    return setup(cellsize, dx, dy);

}

/** retrieve from the index from an element reversely from a pointer to that element.

    The internal memory layout is (for dimx=6, dimy=3):

6  7  8  9  10 11

12 13 14 15 16 17

Note: north and south are reversed, thus the item with index 0 is located in the south-western edge of the grid! */

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>::max();

    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;

}

template <class T>

void Grid<T>::add(const T& summand)

{

    T* pend = end();

    for (T *p=begin(); p!=pend;*p+=summand,++p)

       ;

}

template <class T>

void Grid<T>::multiply(const T& factor)

{

    T* pend = end();

    for (T *p=begin(); p!=pend;*p*=factor,++p)

       ;

}

template <class T>

void  Grid<T>::wipe()

{

    memset(mData, 0, mCount*sizeof(T));

}

template <class T>

void  Grid<T>::wipe(const T value)

{

    /* this does not work properly !!! */

    if (sizeof(T)==sizeof(int)) {

        float temp = value;

        float *pf = &temp;

        memset(mData, *((int*)pf), mCount*sizeof(T));

    } else

        initialize(value);

}

template <class T>

double Grid<T>::distance(const QPoint &p1, const QPoint &p2)

{

    QPointF fp1=cellCenterPoint(p1);

    QPointF fp2=cellCenterPoint(p2);

    double distance = sqrt( (fp1.x()-fp2.x())*(fp1.x()-fp2.x()) + (fp1.y()-fp2.y())*(fp1.y()-fp2.y()));

    return distance;

}

template <class T>

const QPoint Grid<T>::randomPosition() const

{

    return QPoint(irandom(0,mSizeX-1), irandom(0, mSizeY-1));

}

////////////////////////////////////////////////////////////

// grid runner

////////////////////////////////////////////////////////////

template <class T>

void GridRunner<T>::setup(const Grid<T> &target_grid, const QRectF &rectangle)

{

    QPoint upper_left = target_grid.indexAt(rectangle.topLeft());

    QPoint lower_right = target_grid.indexAt(rectangle.bottomRight());

    mCurrent = const_cast<Grid<T> &>(target_grid).ptr(upper_left.x(), upper_left.y());

    mLast = const_cast<Grid<T> &>(target_grid).ptr(lower_right.x()-1, lower_right.y()-1);

    mCols = lower_right.x() - upper_left.x(); //

    mLineLength =  target_grid.sizeX() - mCols;

    mCurrentCol = 0;

}

template <class T>

T* GridRunner<T>::next()

{

    if (mCurrent>mLast)

        return NULL;

    T* t = mCurrent;

    mCurrent++;

    mCurrentCol++;

    if (mCurrentCol >= mCols) {

        mCurrent += mLineLength; // skip to next line

        mCurrentCol = 0;

    }

    return t;

}

////////////////////////////////////////////////////////////

// global functions

////////////////////////////////////////////////////////////

/// dumps a FloatGrid to a String.

/// rows will be y-lines, columns x-values. (see grid.cpp)

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);

/** load into 'rGrid' the content of the image pointed at by 'fileName'.

    Pixels are converted to grey-scale and then transformend to a value ranging from 0..1 (black..white).

  */

bool loadGridFromImage(const QString &fileName, FloatGrid &rGrid);

/// template version for non-float grids (see also version for FloatGrid)

template <class T>

        QString gridToString(const Grid<T> &grid)

{

    QString res;

    QTextStream ts(&res);

    for (int y=0;y<grid.sizeY();y++){

        for (int x=0;x<grid.sizeX();x++){

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

        }

        ts << "\r\n";

    }

    return res;

}

#endif // GRID_H