itkColormapFunction.h

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/*=========================================================================
 *
 *  Copyright NumFOCUS
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *         https://www.apache.org/licenses/LICENSE-2.0.txt
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *=========================================================================*/
#ifndef itkColormapFunction_h
#define itkColormapFunction_h
 
#include "itkObject.h"
#include "itkObjectFactory.h"
#include "itkNumericTraits.h"
#include "itkRGBPixel.h"
 
namespace itk::Function
{
template <typename TScalar, typename TRGBPixel>
class ColormapFunction : public Object
{
public:
  ITK_DISALLOW_COPY_AND_MOVE(ColormapFunction);
 
  using Self = ColormapFunction;
  using Superclass = Object;
  using Pointer = SmartPointer<Self>;
  using ConstPointer = SmartPointer<const Self>;

  itkOverrideGetNameOfClassMacro(ColormapFunction);
 
  using RGBPixelType = TRGBPixel;
  using RGBComponentType = typename TRGBPixel::ComponentType;
  using ScalarType = TScalar;
  using RealType = typename NumericTraits<ScalarType>::RealType;
 
  itkSetMacro(MinimumRGBComponentValue, RGBComponentType);
  itkGetConstMacro(MinimumRGBComponentValue, RGBComponentType);
 
  itkSetMacro(MaximumRGBComponentValue, RGBComponentType);
  itkGetConstMacro(MaximumRGBComponentValue, RGBComponentType);
 
  itkSetMacro(MinimumInputValue, ScalarType);
  itkGetConstMacro(MinimumInputValue, ScalarType);
 
  itkSetMacro(MaximumInputValue, ScalarType);
  itkGetConstMacro(MaximumInputValue, ScalarType);
 
  virtual RGBPixelType
  operator()(const ScalarType &) const = 0;
 
protected:
  ColormapFunction()
    : m_MinimumInputValue(NumericTraits<TScalar>::min())
    , m_MaximumInputValue(NumericTraits<TScalar>::max())
    , m_MinimumRGBComponentValue(NumericTraits<RGBComponentType>::min())
    , m_MaximumRGBComponentValue(NumericTraits<RGBComponentType>::max())
  {}
 
  ~ColormapFunction() override = default;

  RealType
  RescaleInputValue(ScalarType v) const
  {
    auto maxInputValue = static_cast<RealType>(this->m_MaximumInputValue);
    auto minInputValue = static_cast<RealType>(this->m_MinimumInputValue);
 
    auto     d = static_cast<RealType>(maxInputValue - minInputValue);
    RealType value = (static_cast<RealType>(v) - static_cast<RealType>(minInputValue)) / d;
    value = std::clamp(value, 0.0, 1.0);
    return value;
  }

  RGBComponentType
  RescaleRGBComponentValue(RealType v) const
  {
    auto                   d = static_cast<RealType>(m_MaximumRGBComponentValue - m_MinimumRGBComponentValue);
    const RGBComponentType rescaled = static_cast<RGBComponentType>(d * v) + this->m_MinimumRGBComponentValue;
 
    return rescaled;
  }
 
  void
  PrintSelf(std::ostream & os, Indent indent) const override
  {
    Superclass::PrintSelf(os, indent);
 
    os << indent << "Minimum RGB Component Value: "
       << static_cast<typename NumericTraits<RGBComponentType>::PrintType>(this->GetMinimumRGBComponentValue())
       << std::endl;
    os << indent << "Maximum RGB Component Value: "
       << static_cast<typename NumericTraits<RGBComponentType>::PrintType>(this->GetMaximumRGBComponentValue())
       << std::endl;
    os << indent << "Minimum Input Value: "
       << static_cast<typename NumericTraits<ScalarType>::PrintType>(this->GetMinimumInputValue()) << std::endl;
    os << indent << "Maximum Input Value: "
       << static_cast<typename NumericTraits<ScalarType>::PrintType>(this->GetMaximumInputValue()) << std::endl;
  }
 
private:
  ScalarType m_MinimumInputValue{};
  ScalarType m_MaximumInputValue{};
 
  RGBComponentType m_MinimumRGBComponentValue{};
  RGBComponentType m_MaximumRGBComponentValue{};
};
} // namespace itk::Function
 
#endif