# ChooseContrastingColor

### Description

Given a color, find a contrasting color. If the given color is "light", use the lightColor otherwise use the darkColor.

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### Declaration Section

    #include <vtkNamedColors.h>
    #include <vtkMath.h>
    namespace
    {
    // Given a color, find a contrasting color. If the goven color is "light",
    // use the lightColor otherwise use the darkColor
    void ChooseContrastingColor(double *rgbIn,
                                double *rgbOut,
                                const double threshold = .5,
                                const std::string lightColor = "white",
                                const std::string darkColor = "black");
    }

### Implementation Section

    namespace
    {
    void ChooseContrastingColor(double *rgbIn,
                                double *rgbOut,
                                const double threshold,
                                const std::string lightColor,
                                const std::string darkColor)
    {
      vtkSmartPointer<vtkNamedColors> colors =
        vtkSmartPointer<vtkNamedColors>::New();

      double hsv[3];
      // If the value is <= threshold, use a light color, otherwise use a dark color
      vtkMath::RGBToHSV(rgbIn, hsv);
      if (hsv[2] <= threshold)
      {
        colors->GetColor(lightColor.c_str(), rgbOut[0], rgbOut[1], rgbOut[2]);
      }
      else
      {
        colors->GetColor(darkColor.c_str(), rgbOut[0], rgbOut[1], rgbOut[2]);
      }
    }
    }