filter.h

// Description: Filter class
// Detail: Reconstruction filter abstraction
// Documentation: filters.txt

#ifndef PASTELGFX_FILTER_H
#define PASTELGFX_FILTER_H

#include "pastel/sys/mytypes.h"

#include <memory>
#include <string>

namespace Pastel
{

    //! A reconstruction filter.
    /*!
   This class represents different kinds of 1-dimensional
   reconstruction filters. The usage of this class is extended
   to higher dimensions by giving it a radial distance instead
   (for radially symmetric filters) or using it for each
   dimension separately (for separable filters). This class
   would be more properly named a 'ReconstructionFilter'.
   However, this leads to too long names. I decided
   to leave this semantic information for the documentation.
   */

    class Filter
    {
    public:
        // Using default constructor.
        // Using default copy constructor.
        // Using default assignment.

        Filter(real radius,
            const std::string& name)
        : radius_(radius)
        , name_(name)
        {
            ENSURE_OP(radius, >, 0);
        }

        virtual ~Filter()
        {
        }

        //! Evaluates the filter inside the radius.
        /*!
       Preconditions:
       -radius <= position <= radius

       This function performs faster because
       it can leave out range checking.
       */
        virtual real evaluateInRange(real position) const = 0;

        void setRadius(real radius)
        {
            ENSURE_OP(radius, >, 0);
            radius_ = radius;
            onSetRadius();
        }

        real radius() const
        {
            return radius_;
        }

        real evaluate(real x) const
        {
            if (x < -radius_ || x > radius_)
            {
                return 0;
            }

            return evaluateInRange(x);
        }

        const std::string& name() const
        {
            return name_;
        }

    private:
        Filter(const Filter& that) = delete;
        Filter& operator=(const Filter& that) = delete;

        virtual void onSetRadius()
        {
        }

        real radius_;
        std::string name_;
    };

    using FilterPtr = std::shared_ptr<Filter>;
    using ConstFilterPtr = std::shared_ptr<const Filter>;

}

#endif