VtkColorLookupTable.cpp

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// SPDX-FileCopyrightText: Copyright (c) OpenGeoSys Community (opengeosys.org)
// SPDX-License-Identifier: BSD-3-Clause
 
#include "VtkColorLookupTable.h"
 
#include <vtkObjectFactory.h>
 
#include <cmath>
#include <sstream>
 
#include "Applications/DataHolderLib/Color.h"
#include "BaseLib/Logging.h"
 
vtkStandardNewMacro(VtkColorLookupTable);
 
VtkColorLookupTable::VtkColorLookupTable() = default;
 
VtkColorLookupTable::~VtkColorLookupTable()
{
    for (auto& it : _dict)
    {
        delete it.second;
    }
}
 
unsigned char VtkColorLookupTable::linInterpolation(unsigned char a,
                                                    unsigned char b,
                                                    double p) const
{
    return static_cast<unsigned char>(a * (1 - p) + b * p);
}
 
unsigned char VtkColorLookupTable::expInterpolation(unsigned char a,
                                                    unsigned char b,
                                                    double gamma,
                                                    double p) const
{
    assert(gamma > 0 && gamma < 4);
    return static_cast<unsigned char>((b - a) * pow(p, gamma) + a);
}
 
void VtkColorLookupTable::Build()
{
    double range[2];
    this->GetTableRange(range);
    const double interval = range[1] - range[0];
    this->SetNumberOfTableValues(static_cast<vtkIdType>(ceil(interval)) + 1);
    //    const vtkIdType nColours = this->GetNumberOfTableValues();
    if (!_dict.empty())
    {
        // make sure that color map starts with the first color in the
        // dictionary
        unsigned char startcolor[4] = {0, 0, 0, 0};
        std::pair<std::size_t, unsigned char*> lastValue(0, startcolor);
 
        for (auto& it : _dict)
        {
            double val = (it.first < range[0])
                             ? range[0]
                             : ((it.first > range[1]) ? range[1] : it.first);
            auto const nextIndex =
                static_cast<std::size_t>(std::floor(val - range[0]));
 
            this->SetTableValueRGBA(nextIndex, it.second);
 
            if (nextIndex - lastValue.first > 0)
            {
                for (std::size_t i = lastValue.first + 1; i < nextIndex; i++)
                {
                    unsigned char int_rgba[4];
                    double pos =
                        (i - lastValue.first) /
                        (static_cast<double>(nextIndex - lastValue.first));
 
                    if (_type == DataHolderLib::LUTType::LINEAR)
                    {
                        for (std::size_t j = 0; j < 4; j++)
                        {
                            int_rgba[j] = linInterpolation(
                                (lastValue.second)[j], (it.second)[j], pos);
                        }
                    }
                    else if (_type == DataHolderLib::LUTType::EXPONENTIAL)
                    {
                        for (std::size_t j = 0; j < 4; j++)
                        {
                            int_rgba[j] =
                                expInterpolation((lastValue.second)[j],
                                                 (it.second)[j], 0.2, pos);
                        }
                    }
                    else
                    {  // no interpolation
                        for (std::size_t j = 0; j < 4; j++)
                        {
                            int_rgba[j] = (lastValue.second)[j];
                        }
                    }
 
                    this->SetTableValueRGBA(i, int_rgba);
                }
            }
 
            lastValue.first = nextIndex;
            lastValue.second = it.second;
        }
    }
    else
    {
        vtkLookupTable::Build();
    }
}
 
void VtkColorLookupTable::setLookupTable(
    DataHolderLib::ColorLookupTable const& lut)
{
    std::size_t const n_colors(lut.size());
    for (std::size_t i = 0; i < n_colors; ++i)
    {
        setColor(std::get<0>(lut[i]), std::get<1>(lut[i]));
    }
    setInterpolationType(lut.getInterpolationType());
    auto const range(lut.getTableRange());
    SetTableRange(range.first, range.second);
    Build();
}
 
void VtkColorLookupTable::writeToFile(const std::string& filename)
{
    std::stringstream strout;
    strout << "Writing color table to " << filename << " ... ";
    std::ofstream out(filename.c_str(), std::ios::out);
 
    std::size_t nColors = this->GetNumberOfTableValues();
    for (std::size_t i = 0; i < nColors; i++)
    {
        unsigned char rgba[4];
        this->GetTableValue(i, rgba);
        out << i << "\t" << rgba[0] << "\t" << rgba[1] << "\t" << rgba[2]
            << "\n";
    }
 
    strout << " done." << std::endl;
    INFO("{:s}", strout.str());
    out.close();
}
 
void VtkColorLookupTable::SetTableValueRGBA(vtkIdType idx,
                                            unsigned char rgba[4])
{
    double value[4];
 
    for (unsigned i = 0; i < 4; ++i)
    {
        value[i] = rgba[i] / 255.0;
    }
    vtkLookupTable::SetTableValue(idx, value);
}
 
void VtkColorLookupTable::GetTableValue(vtkIdType idx, unsigned char rgba[4])
{
    double value[4];
    vtkLookupTable::GetTableValue(idx, value);
 
    for (unsigned i = 0; i < 4; ++i)
    {
        rgba[i] = static_cast<unsigned char>(value[i] * 255.0);
    }
}
 
void VtkColorLookupTable::setColor(double pos,
                                   DataHolderLib::Color const& color)
{
    auto* dict_rgba = new unsigned char[4];
    for (std::size_t i = 0; i < 4; i++)
    {
        dict_rgba[i] = color[i];
    }
    _dict.insert(std::pair<double, unsigned char*>(pos, dict_rgba));
}
 
void VtkColorLookupTable::getColor(vtkIdType index, unsigned char rgba[4]) const
{
    index = ((index < this->TableRange[0])
                 ? static_cast<vtkIdType>(this->TableRange[0])
                 : (index >= this->TableRange[1]
                        ? static_cast<vtkIdType>(this->TableRange[1]) - 1
                        : index));
    index = static_cast<std::size_t>(std::floor(
        (index - this->TableRange[0]) *
        (this->NumberOfColors / (this->TableRange[1] - this->TableRange[0]))));
 
    unsigned char* _rgba;
    _rgba = this->Table->GetPointer(index * 4);
    for (std::size_t i = 0; i < 4; i++)
    {
        rgba[i] = _rgba[i];
    }
}