Indoor/math/boxkde/Image2D.h

#pragma once

#include <algorithm>
#include <cassert>
#include <numeric>
#include <vector>

#include "DataStructures.h"

enum struct LineDirection { X, Y };

template <typename TValue>
struct ImageView2D
{
    static_assert(std::is_arithmetic<TValue>::value, "Image only supports integers or floats");

    // forward declaration
    //enum struct LineDirection;
    template<LineDirection D> struct LineView;
    template<LineDirection D> struct ConstLineView;

    size_t width, height, size;
protected:
    TValue* values; // contains image data row-wise 

public:
    ImageView2D()
        : width(0), height(0), size(0), values(nullptr)
    { }

    ImageView2D(size_t width, size_t height)
        : width(width), height(height), size(width*height), values(nullptr)
    { }

    ImageView2D(size_t width, size_t height, TValue* data)
        : width(width), height(height), size(width*height), values(data)
    { }

    inline       TValue& operator() (size_t x, size_t y)       { return values[indexFromCoord(x, y)]; }
    inline const TValue& operator() (size_t x, size_t y) const { return values[indexFromCoord(x, y)]; }

    TValue* val_begin() { return values; }
    TValue* val_end  () { return values + size; }

    const TValue* val_begin() const { return values; }
    const TValue* val_end  () const { return values + size; }

    inline size_t indexFromCoord(size_t x, size_t y) const
    {
        assertMsg(x < width && y < height, "(x,y) out of bounds");
        return y * width + x;
    }

    Point2D<size_t> coordFromIndex(size_t index) const
    {
        assertMsg(index < size, "Index out of bounds");
        return Point2D<size_t>(index % width, index / width);
    }

    Point2D<size_t> maximum() const
    {
        size_t maxValueIndex = std::distance(val_begin(), std::max_element(val_begin(), val_end()));
        return coordFromIndex(maxValueIndex);
    }

    TValue maximum(Point2D<size_t>& pt) const
    {
        size_t maxValueIndex = std::distance(val_begin(), std::max_element(val_begin(), val_end()));
        pt = coordFromIndex(maxValueIndex);
        return values[maxValueIndex];
    }

    void clear()
    {
        fill(TValue(0));
    }

    void fill(TValue value)
    {
        std::fill(val_begin(), val_end(), value);
    }
    
    void assign(const ImageView2D<TValue>& other)
    {
        assertMsg(size == other.size, "Other must be of the same size as this");
        std::copy(other.val_begin(), other.val_end(), val_begin());
    }

    TValue sum() const
    {
        return std::accumulate(val_begin(), val_end(), TValue(0));
    }

    // Returns a transposed view of this image without copying any data.
    ImageView2D<TValue> transpose() const
    {
        return ImageView2D<TValue>(height, width, values);
    }

    // Returns the value at (x,y). Throws if out of bounds.
    const TValue& at(size_t x, size_t y) const
    {
        return values[indexFromCoord(x, y)];
    }

    // Returns the value at (x,y) but falls back to default if out of bounds.
    const TValue& get(size_t x, size_t y, TValue dflt = 0) const
    {
        if (x >= width || y >= height)
            return dflt;
        else
            return values[indexFromCoord(x, y)];
    }
    
    std::vector<Point2D<size_t>> findLocalMaxima(int radiusX = 1, int radiusY = 1) const
    {
        std::vector<Point2D<size_t>> result;
        findLocalMaxima(result, radiusX, radiusY);
        return result;
    }

    void findLocalMaxima(std::vector<Point2D<size_t>>& result, int radiusX = 1, int radiusY = 1) const
    {
        assertMsg(radiusX > 0, "Search radius must be greater than 0.");

        for (size_t y = 0; y < height; y++)
        {
            for (size_t x = 0; x < width; x++)
            {
                TValue val = at(x, y);
                bool lclMax = true;

                for (int ry = -radiusY; ry <= radiusY; ry++)
                {
                    for (int rx = -radiusX; rx <= radiusX; rx++)
                    {
                        TValue other = get(x + rx, y + ry);
                        if (!(rx == 0 && ry == 0) && val <= other)
                        {
                            lclMax = false;
                        }
                    }
                }

                if (lclMax)
                {
                    result.emplace_back(x, y);
                }
            }
        }
    }
};

template <class TValue>
struct Image2D : public ImageView2D<TValue>
{
	static_assert(std::is_arithmetic<TValue>::value, "Image only supports integers or floats");

	std::vector<TValue> values_vec;

	Image2D()
	{
	}

	Image2D(size_t width, size_t height)
        : ImageView2D<TValue>(width, height), values_vec(width * height)
	{
        this->values = values_vec.data();
    }

    Image2D(size_t width, size_t height, std::vector<TValue>& data)
        : ImageView2D<TValue>(width, height), values_vec(data)
    {
        assertMsg(data.size() == width*height, "Sizes must be the same");
        this->values = values_vec.data();
    }

          std::vector<TValue>& data()       { return values_vec; }
    const std::vector<TValue>& data() const { return values_vec; }
};


template struct ImageView2D<float>;
template struct ImageView2D<double>;

template struct Image2D<float>;
template struct Image2D<double>;