hyperion.ng/include/utils/Image.h

#pragma once

// STL includes
#include <vector>
#include <cstdint>
#include <cstring>
#include <algorithm>

template <typename Pixel_T>
class Image
{
public:

    typedef Pixel_T pixel_type;

    ///
    /// Default constructor for an image
    ///
    Image() :
        _width(1),
        _height(1),
        _pixels(new Pixel_T[2]),
        _endOfPixels(_pixels + 1)
    {
        memset(_pixels, 0, 2*sizeof(Pixel_T));
    }

    ///
    /// Constructor for an image with specified width and height
    ///
    /// @param width The width of the image
    /// @param height The height of the image
    ///
    Image(const unsigned width, const unsigned height) :
        _width(width),
        _height(height),
        _pixels(new Pixel_T[width * height + 1]),
        _endOfPixels(_pixels + width * height)
    {
        memset(_pixels, 0, (_width*_height+1)*sizeof(Pixel_T));
    }

    ///
    /// Constructor for an image with specified width and height
    ///
    /// @param width The width of the image
    /// @param height The height of the image
    /// @param background The color of the image
    ///
    Image(const unsigned width, const unsigned height, const Pixel_T background) :
        _width(width),
        _height(height),
        _pixels(new Pixel_T[width * height + 1]),
        _endOfPixels(_pixels + width * height)
    {
        std::fill(_pixels, _endOfPixels, background);
    }

    ///
    /// Copy constructor for an image
    ///
    Image(const Image & other) :
        _width(other._width),
        _height(other._height),
        _pixels(new Pixel_T[other._width * other._height + 1]),
        _endOfPixels(_pixels + other._width * other._height)
    {
        memcpy(_pixels, other._pixels, other._width * other._height * sizeof(Pixel_T));
    }

    ///
    /// Destructor
    ///
    ~Image()
    {
        delete[] _pixels;
    }

    ///
    /// Returns the width of the image
    ///
    /// @return The width of the image
    ///
    inline unsigned width() const
    {
        return _width;
    }

    ///
    /// Returns the height of the image
    ///
    /// @return The height of the image
    ///
    inline unsigned height() const
    {
        return _height;
    }

    uint8_t red(const unsigned pixel) const
    {
        return (_pixels + pixel)->red;
    }

    uint8_t green(const unsigned pixel) const
    {
        return (_pixels + pixel)->green;
    }

    uint8_t blue(const unsigned pixel) const
    {
        return (_pixels + pixel)->blue;
    }

    ///
    /// Returns a const reference to a specified pixel in the image
    ///
    /// @param x The x index
    /// @param y The y index
    ///
    /// @return const reference to specified pixel
    ///
    const Pixel_T& operator()(const unsigned x, const unsigned y) const
    {
        return _pixels[toIndex(x,y)];
    }

    ///
    /// Returns a reference to a specified pixel in the image
    ///
    /// @param x The x index
    /// @param y The y index
    ///
    /// @return reference to specified pixel
    ///
    Pixel_T& operator()(const unsigned x, const unsigned y)
    {
        return _pixels[toIndex(x,y)];
    }

    /// Resize the image
    /// @param width The width of the image
    /// @param height The height of the image
    void resize(const unsigned width, const unsigned height)
    {
        if ((width*height) > unsigned((_endOfPixels-_pixels)))
        {
            delete[] _pixels;
            _pixels = new Pixel_T[width*height + 1];
            _endOfPixels = _pixels + width*height;
        }

        _width = width;
        _height = height;
    }

    ///
    /// Copies another image into this image. The images should have exactly the same size.
    ///
    /// @param other The image to copy into this
    ///
    void copy(const Image<Pixel_T>& other)
    {
        assert(other._width == _width);
        assert(other._height == _height);

        memcpy(_pixels, other._pixels, _width*_height*sizeof(Pixel_T));
    }

    ///
    /// Returns a memory pointer to the first pixel in the image
    /// @return The memory pointer to the first pixel
    ///
    Pixel_T* memptr()
    {
        return _pixels;
    }

    ///
    /// Returns a const memory pointer to the first pixel in the image
    /// @return The const memory pointer to the first pixel
    ///
    const Pixel_T* memptr() const
    {
        return _pixels;
    }
private:

    ///
    /// Translate x and y coordinate to index of the underlying vector
    ///
    /// @param x The x index
    /// @param y The y index
    ///
    /// @return The index into the underlying data-vector
    ///
    inline unsigned toIndex(const unsigned x, const unsigned y) const
    {
        return y*_width + x;
    }

private:
    /// The width of the image
    unsigned _width;
    /// The height of the image
    unsigned _height;

    /// The pixels of the image
    Pixel_T* _pixels;

    /// Pointer to the last(extra) pixel
    Pixel_T* _endOfPixels;
};