itkLabelToRGBFunctor.h

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/*=========================================================================
 *
 *  Copyright Insight Software Consortium
 *
 *  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
 *
 *         http://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 itkLabelToRGBFunctor_h
#define itkLabelToRGBFunctor_h

#include <vector>
#include "itkNumericTraits.h"

namespace itk
{
namespace Functor
{
template< typename TLabel, typename TRGBPixel >
class LabelToRGBFunctor
{
public:

  using Self = LabelToRGBFunctor;

  LabelToRGBFunctor()
  {
    using ValueType = typename TRGBPixel::ValueType;

    // the following colors are from "R", and named:
    // "red"             "green3"          "blue"            "cyan"
    //"magenta"         "darkorange1"     "darkgreen"       "blueviolet"
    //"brown4"          "navy"            "yellow4"         "violetred1"
    //"salmon4"         "turquoise4"      "sienna3"         "darkorchid1"
    //"springgreen4"    "mediumvioletred" "orangered3"      "lightseagreen"
    //"slateblue"       "deeppink1"       "aquamarine4"     "royalblue1"
    //"tomato3"         "mediumblue"      "violetred4"      "darkmagenta"
    //"violet"          "red4"
    // They are a good selection of distinct colors for plotting and
    // overlays.
    constexpr size_t numColors  = 30;
    constexpr unsigned char colors[numColors][3] = {
      {255, 0, 0}, {0, 205, 0}, {0, 0, 255}, {0, 255, 255},
      {255, 0, 255}, {255, 127, 0}, {0, 100, 0}, {138, 43, 226},
      {139, 35, 35}, {0, 0, 128}, {139, 139, 0}, {255, 62, 150},
      {139, 76, 57}, {0, 134, 139}, {205, 104, 57}, {191, 62, 255},
      {0, 139, 69}, {199, 21, 133}, {205, 55, 0}, {32, 178, 170},
      {106, 90, 205}, {255, 20, 147}, {69, 139, 116}, {72, 118, 255},
      {205, 79, 57}, {0, 0, 205}, {139, 34, 82}, {139, 0, 139},
      {238, 130, 238}, {139, 0, 0}
    };

    for (auto & color : colors)
      {
      AddColor(color[0], color[1], color[2]);
      }

    // provide some default value for external use (outside
    // LabelToRGBImageFilter)
    // Inside LabelToRGBImageFilter, the values are always initialized
    NumericTraits<TRGBPixel>::SetLength( m_BackgroundColor, 3);
    m_BackgroundColor.Fill(NumericTraits< ValueType >::ZeroValue());
    m_BackgroundValue = NumericTraits< TLabel >::ZeroValue();
  }

  inline TRGBPixel operator()(const TLabel & p) const
  {
    // value is background
    // return a gray pixel with the same intensity than the label pixel
    if ( p == m_BackgroundValue )
      {
      return m_BackgroundColor;
      }

    // else, return a colored pixel from the color table
    return m_Colors[p % m_Colors.size()];
  }

  void AddColor(unsigned char r, unsigned char g, unsigned char b)
  {
    TRGBPixel rgbPixel;
    NumericTraits<TRGBPixel>::SetLength(rgbPixel, 3);

    using ValueType = typename TRGBPixel::ValueType;

    ValueType m = NumericTraits<ValueType>::max();

    rgbPixel[0] = static_cast< ValueType >( static_cast< double >( r ) / 255 * m );
    rgbPixel[1] = static_cast< ValueType >( static_cast< double >( g ) / 255 * m );
    rgbPixel[2] = static_cast< ValueType >( static_cast< double >( b ) / 255 * m );
    m_Colors.push_back(rgbPixel);
  }

  // Empty the color LUT
  void ResetColors()
  {
    m_Colors.clear();
  }

  // Get number of colors in the LUT
  unsigned int GetNumberOfColors() const
  {
    return static_cast<unsigned int>( m_Colors.size() );
  }

  bool operator!=(const Self & l) const
  {
    if ( m_BackgroundColor != l.m_BackgroundColor
         || m_BackgroundValue != l.m_BackgroundValue
         || m_Colors.size() != l.m_Colors.size() )
      {
      return true;
      }

    // We need to check each color to see if it's different
    for ( typename std::vector< TRGBPixel >::size_type i = 0; i < m_Colors.size(); ++i )
      {
      if ( m_Colors[i] != l.m_Colors[i] )
        {
        return true;
        }
      }
    return false;
  }

  bool operator==(const Self & other) const
  {
    return !( *this != other );
  }

  void SetBackgroundValue(TLabel v)
  {
    m_BackgroundValue = v;
  }

  void SetBackgroundColor(TRGBPixel rgb)
  {
    m_BackgroundColor = rgb;
  }

  ~LabelToRGBFunctor() = default;

  std::vector< TRGBPixel > m_Colors;

  TRGBPixel m_BackgroundColor;

  TLabel m_BackgroundValue;
};
}  // end namespace Functor
}  // end namespace itk

#endif