color_tools.h

// Description: Algorithms for colors

#ifndef PASTELGFX_COLOR_TOOLS_H
#define PASTELGFX_COLOR_TOOLS_H

#include "pastel/gfx/color/color.h"
#include "pastel/gfx/color/coloradapter.h"

namespace Pastel
{

    //! Generates a random rgb color.

    Color randomRgbColor();

    //! Returns the weights of the rgb-to-luma conversion.

    Color lumaWeights();

    //! Computes the luma of an rgb color.
    /*!
   The luma is computed from non-linear sRGB values
   and is a crude approximation to lightness. An ideal
   conversion would convert to CIELab, zero the ab components
   and convert back to sRGB. This is quite costly an
   operation and for many applications luma does good enough.
   */
    real32 luma(const Color& rgb);

    //! Sets all colors out of the [0, 1] range to black.
    Color fitColorBlack(const Color& rgb);

    //! Fits an rgb color to [0, 1]^3 range while preserving hue.
    /*!
   Components less than zero are set to zero.
   If a color has a component greater than 1, then
   the color is normalized by max(rgb). This operation
   maps the color to the legal range by decreasing intensity
   while preserving hue.
   If no such cases apply, the color is returned as it is.
   */
    Color fitColor(const Color& rgb);

    //! Sets negative components to zero.
    Color fitNegativeColor(const Color& rgb);

    class Luma_Color_Adapter
    {
    public:
        using Logical = Color;
        using Physical = real32;

        Logical convert(const Physical& physical) const
        {
            return Color(physical);
        }

        Physical revert(const Logical& logical) const
        {
            return luma(logical);
        }
    };

    using Color_Luma_Adapter = ReverseAdapter<Luma_Color_Adapter>;

}

#include "pastel/gfx/color/color_tools.hpp"

#endif