VtkColorLookupTable Class Reference

Detailed Description

Calculates and stores a colour lookup table.

Based on a start colour and an end colour, RGB-values are interpolated and stored in vector of GeoLib::Color. If no colours are set, default values are used for start (blue) and end (red). The number of entries of the colour table can be set in the constructor, the default value is 256. If additional colours are inserted into the table using setColor() the interpolation will be calculated iteratively between set colour values. Interpolation can be linear (default) or exponential. Based on the set range of values, colour values can be retrieved using getColor().

Definition at line 23 of file VtkColorLookupTable.h.

#include <VtkColorLookupTable.h>

Inheritance diagram for VtkColorLookupTable:

Collaboration diagram for VtkColorLookupTable:

Public Member Functions
	vtkTypeMacro (VtkColorLookupTable, vtkLookupTable)
void	Build () override
	Builds the colour table based on the previously set parameters. This method should only be called after all options have been set.
void	setColor (double pos, DataHolderLib::Color const &color)
void	getColor (vtkIdType index, unsigned char rgba[4]) const
DataHolderLib::LUTType	getInterpolationType () const
	Returns the type of interpolation used.
void	setInterpolationType (DataHolderLib::LUTType type)
	Sets the type of interpolation.
void	setLookupTable (DataHolderLib::ColorLookupTable const &lut)
	Imports settings of OGS lookup table class.
void	writeToFile (const std::string &filename)
	Exports a color table to a file.
void	SetTableValueRGBA (vtkIdType idx, unsigned char rgba[4])
	Set a value within the LUT.
void	GetTableValue (vtkIdType idx, unsigned char rgba[4])
	Get a value from the LUT.

Static Public Member Functions
static VtkColorLookupTable *	New ()
	Create new objects with New() because of VTKs object reference counting.

Static Public Attributes
static const int	DEFAULTMINVALUE = -9999
static const int	DEFAULTMAXVALUE = 9999

Protected Member Functions
	VtkColorLookupTable ()
	Constructor.
	~VtkColorLookupTable () override
	Destructor.

Private Member Functions
unsigned char	linInterpolation (unsigned char a, unsigned char b, double p) const
	Interpolates values linearly.
unsigned char	expInterpolation (unsigned char a, unsigned char b, double gamma, double p) const
	Interpolates values exponentially. gamma should roughly be in [0,4), for gamma=1 interpolation is linear.

Private Attributes
std::map< double, unsigned char * >	_dict
DataHolderLib::LUTType	_type {DataHolderLib::LUTType::LINEAR}

Constructor & Destructor Documentation

VtkColorLookupTable()

VtkColorLookupTable::VtkColorLookupTable ( )

protecteddefault

Constructor.

Referenced by New(), and vtkTypeMacro().

~VtkColorLookupTable()

VtkColorLookupTable::~VtkColorLookupTable ( )

overrideprotected

Destructor.

Definition at line 18 of file VtkColorLookupTable.cpp.

{
    for (auto& it : _dict)
    {
        delete it.second;
    }
}

References _dict.

Member Function Documentation

Build()

void VtkColorLookupTable::Build ( )

override

Builds the colour table based on the previously set parameters. This method should only be called after all options have been set.

Definition at line 42 of file VtkColorLookupTable.cpp.

{
    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();
    }
}

References _dict, _type, expInterpolation(), DataHolderLib::EXPONENTIAL, DataHolderLib::LINEAR, linInterpolation(), and SetTableValueRGBA().

Referenced by VtkCompositeElementSelectionFilter::GetLookupTable(), VtkCompositeColorByHeightFilter::init(), and setLookupTable().

expInterpolation()

unsigned char VtkColorLookupTable::expInterpolation ( unsigned char a, unsigned char b, double gamma, double p ) const

private

Interpolates values exponentially. gamma should roughly be in [0,4), for gamma=1 interpolation is linear.

Definition at line 33 of file VtkColorLookupTable.cpp.

{
    assert(gamma > 0 && gamma < 4);
    return static_cast<unsigned char>((b - a) * pow(p, gamma) + a);
}

Referenced by Build().

getColor()

void VtkColorLookupTable::getColor	(	vtkIdType	index,
		unsigned char	rgba[4] ) const

Definition at line 182 of file VtkColorLookupTable.cpp.

{
    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];
    }
}

getInterpolationType()

DataHolderLib::LUTType VtkColorLookupTable::getInterpolationType ( ) const

inline

Returns the type of interpolation used.

Definition at line 52 of file VtkColorLookupTable.h.

{ return _type; }

References _type.

GetTableValue()

void VtkColorLookupTable::GetTableValue	(	vtkIdType	idx,
		unsigned char	rgba[4] )

Get a value from the LUT.

Definition at line 160 of file VtkColorLookupTable.cpp.

{
    double value[4];
    vtkLookupTable::GetTableValue(idx, value);
 
    for (unsigned i = 0; i < 4; ++i)
    {
        rgba[i] = static_cast<unsigned char>(value[i] * 255.0);
    }
}

Referenced by writeToFile().

linInterpolation()

unsigned char VtkColorLookupTable::linInterpolation ( unsigned char a, unsigned char b, double p ) const

private

Interpolates values linearly.

Definition at line 26 of file VtkColorLookupTable.cpp.

{
    return static_cast<unsigned char>(a * (1 - p) + b * p);
}

Referenced by Build().

New()

VtkColorLookupTable * VtkColorLookupTable::New ( )

static

Create new objects with New() because of VTKs object reference counting.

References VtkColorLookupTable().

Referenced by VtkCompositeElementSelectionFilter::GetLookupTable(), and VtkAlgorithmProperties::SetLookUpTable().

setColor()

void VtkColorLookupTable::setColor	(	double	pos,
		DataHolderLib::Color const &	color )

Definition at line 171 of file VtkColorLookupTable.cpp.

{
    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));
}

References _dict.

Referenced by VtkCompositeElementSelectionFilter::GetLookupTable(), VtkCompositeColorByHeightFilter::init(), and setLookupTable().

setInterpolationType()

void VtkColorLookupTable::setInterpolationType ( DataHolderLib::LUTType type )

inline

Sets the type of interpolation.

Definition at line 55 of file VtkColorLookupTable.h.

{ _type = type; }

References _type.

Referenced by VtkCompositeColorByHeightFilter::init(), and setLookupTable().

setLookupTable()

void VtkColorLookupTable::setLookupTable

(

DataHolderLib::ColorLookupTable const &

lut

)

Imports settings of OGS lookup table class.

Definition at line 114 of file VtkColorLookupTable.cpp.

{
    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();
}

References Build(), DataHolderLib::ColorLookupTable::getInterpolationType(), DataHolderLib::ColorLookupTable::getTableRange(), setColor(), setInterpolationType(), and DataHolderLib::ColorLookupTable::size().

Referenced by VtkAlgorithmProperties::SetLookUpTable().

SetTableValueRGBA()

void VtkColorLookupTable::SetTableValueRGBA	(	vtkIdType	idx,
		unsigned char	rgba[4] )

Set a value within the LUT.

Definition at line 148 of file VtkColorLookupTable.cpp.

{
    double value[4];
 
    for (unsigned i = 0; i < 4; ++i)
    {
        value[i] = rgba[i] / 255.0;
    }
    vtkLookupTable::SetTableValue(idx, value);
}

Referenced by Build().

vtkTypeMacro()

VtkColorLookupTable::vtkTypeMacro	(	VtkColorLookupTable	,
		vtkLookupTable	)

References VtkColorLookupTable().

writeToFile()

void VtkColorLookupTable::writeToFile

(

const std::string &

filename

)

Exports a color table to a file.

Definition at line 128 of file VtkColorLookupTable.cpp.

{
    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();
}

References GetTableValue(), and INFO().

Member Data Documentation

_dict

std::map<double, unsigned char*> VtkColorLookupTable::_dict

private

Definition at line 83 of file VtkColorLookupTable.h.

Referenced by ~VtkColorLookupTable(), Build(), and setColor().

_type

DataHolderLib::LUTType VtkColorLookupTable::_type {DataHolderLib::LUTType::LINEAR}

private

Definition at line 84 of file VtkColorLookupTable.h.

{DataHolderLib::LUTType::LINEAR};

Referenced by Build(), getInterpolationType(), and setInterpolationType().

DEFAULTMAXVALUE

const int VtkColorLookupTable::DEFAULTMAXVALUE = 9999

static

Definition at line 27 of file VtkColorLookupTable.h.

DEFAULTMINVALUE

const int VtkColorLookupTable::DEFAULTMINVALUE = -9999

static

Definition at line 26 of file VtkColorLookupTable.h.

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The documentation for this class was generated from the following files:

• VtkColorLookupTable.h
• VtkColorLookupTable.cpp