table_filter.hpp

#ifndef PASTELGFX_TABLE_FILTER_HPP
#define PASTELGFX_TABLE_FILTER_HPP

#include "pastel/gfx/filter/table_filter.h"

#include "pastel/sys/view/subview.h"
#include "pastel/sys/view/view_tools.h"
#include "pastel/sys/view/arrayview.h"

#include "pastel/sys/math_functions.h"

namespace Pastel
{

    inline Table_Filter::Table_Filter(
        const Array<real, 1>& data,
        real radius)
        : Filter(radius, "table")
        , data_()
        , center_(0)
        , scaling_(0)
    {
        integer Padding = 1;
        integer width = data.width();

        ENSURE(odd(width));

        const integer paddedWidth = width + 2 * Padding;

        data_.setExtent(paddedWidth, 0);

        copy(constArrayView(data),
            subView(arrayView(data_), 
            AlignedBox<integer, 1>(Padding, paddedWidth - Padding)));

        center_ = paddedWidth / 2;
        scaling_ = (width / 2) / Filter::radius();
    }

    inline Table_Filter::~Table_Filter()
    {
    }

    inline real Table_Filter::evaluateInRange(real x) const
    {
        real filterPos =
            center_ + x * scaling_;

        integer filterIndex =
            (integer)filterPos;

        return linear(
            data_(filterIndex),
            data_(filterIndex + 1), 
            filterPos - filterIndex);
    }

    inline void Table_Filter::onSetRadius()
    {
        scaling_ = (data_.width() / 2) / radius();
    }

    inline TableFilterPtr tableFilter(
        const ConstFilterPtr& filter,
        integer samplesPerRadius)
    {
        ENSURE_OP(samplesPerRadius, >=, 0);

        real filterRadius = filter->radius();
        integer filterTableRadius =
            std::ceil(samplesPerRadius * filterRadius);
        integer filterTableSize =
            filterTableRadius * 2 + 1;
        Array<real, 1> filterTable(filterTableSize);

        for (integer i = 0;i < filterTableSize;++i)
        {
            real filterPosition =
                (2 * dequantizeUnsignedMatchEnds(i, filterTableSize) - 1) * filterRadius;

            filterTable(i) = filter->evaluateInRange(filterPosition);
        }

        return std::make_shared<Table_Filter>(filterTable, filterRadius);
    }

}

#endif