BUG: Use one calculator in ItermodesThresholder

Use the parent class's calculator and override GenerateDate method to
update the derived calculators ivars. Store the calculator parameters
as filter ivar, with correct filter modified time management.

Closes #1720.

Co-Authored: Jon Haitz Legarreta Gorroño <jon.haitz.legarreta@gmail.com>

Author: blowekamp

Modules/Filtering/Thresholding/include/itkIntermodesThresholdImageFilter.h

@@ -93,31 +93,15 @@ class IntermodesThresholdImageFilter : public HistogramThresholdImageFilter<TInp
   using HistogramType = typename Superclass::HistogramType;
   using CalculatorType = IntermodesThresholdCalculator<HistogramType, InputPixelType>;
 
-  void
-  SetMaximumSmoothingIterations(SizeValueType maxSmoothingIterations)
-  {
-    m_IntermodesCalculator->SetMaximumSmoothingIterations(maxSmoothingIterations);
-  }
 
-  SizeValueType
-  GetMaximumSmoothingIterations()
-  {
-    return (m_IntermodesCalculator->GetMaximumSmoothingIterations());
-  }
+  itkSetMacro(MaxSmoothingIterations, SizeValueType);
+  itkGetMacro(MaxSmoothingIterations, SizeValueType);
 
   /** Select whether midpoint (intermode=true) or minimum between
      peaks is used. */
-  void
-  SetUseInterMode(bool useIntermode)
-  {
-    m_IntermodesCalculator->SetUseInterMode(useIntermode);
-  }
-
-  bool
-  GetUseInterMode()
-  {
-    return (m_IntermodesCalculator->GetUseInterMode());
-  }
+  itkSetMacro(UseInterMode, bool);
+  itkGetConstReferenceMacro(UseInterMode, bool);
+  itkBooleanMacro(UseInterMode);
 
   /** Image related type alias. */
   static constexpr unsigned int InputImageDimension = InputImageType::ImageDimension;
@@ -126,23 +110,44 @@ class IntermodesThresholdImageFilter : public HistogramThresholdImageFilter<TInp
 protected:
   IntermodesThresholdImageFilter()
   {
-    m_IntermodesCalculator = CalculatorType::New();
-    this->SetCalculator(m_IntermodesCalculator);
-    m_IntermodesCalculator->SetMaximumSmoothingIterations(10000);
-    m_IntermodesCalculator->SetUseInterMode(true);
+    auto calculator = CalculatorType::New();
+    calculator->SetMaximumSmoothingIterations(m_MaxSmoothingIterations);
+    calculator->SetUseInterMode(m_UseInterMode);
+    Superclass::SetCalculator(calculator);
   }
   ~IntermodesThresholdImageFilter() override = default;
 
+  void
+  VerifyPreconditions() ITKv5_CONST override
+  {
+    Superclass::VerifyPreconditions();
+    if (dynamic_cast<const CalculatorType *>(Superclass::GetCalculator()) == nullptr)
+    {
+      itkExceptionMacro(<< "Invalid IntermodesCalculator.");
+    }
+  }
+
+  void
+  GenerateData() override
+  {
+    auto calculator = static_cast<CalculatorType *>(this->Superclass::GetModifiableCalculator());
+    calculator->SetMaximumSmoothingIterations(m_MaxSmoothingIterations);
+    calculator->SetUseInterMode(m_UseInterMode);
+    this->Superclass::GenerateData();
+  }
+
+
   void
   PrintSelf(std::ostream & os, Indent indent) const override
   {
     Superclass::PrintSelf(os, indent);
-
-    itkPrintSelfObjectMacro(IntermodesCalculator);
+    os << indent << "MaxSmoothingIterations: " << m_MaxSmoothingIterations << std::endl;
+    os << indent << "UseIterMode: " << m_UseInterMode << std::endl;
   }
 
 private:
-  typename CalculatorType::Pointer m_IntermodesCalculator;
+  SizeValueType m_MaxSmoothingIterations{ 1000 };
+  bool          m_UseInterMode{ true };
 };
 
 } // end namespace itk