ENH: Register default curvilinear FFT factory overrides

Leverages ITK Python factory updates introduced in 10320a6 to initialize
default backends to run FFT on
`itk::CurvilinearArraySpecialCoordinatesImage` objects. Includes
additional wrappings for image inputs.

Closes issue KitwareMedical#172.

include/itkCurvilinearFFTImageFilterInitFactory.h

@@ -0,0 +1,80 @@
+/*=========================================================================
+ *
+ *  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
+ *
+ *         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 itkCurvilinearFFTImageFilterInitFactory_h
+#define itkCurvilinearFFTImageFilterInitFactory_h
+#include "UltrasoundExport.h"
+
+#include "itkLightObject.h"
+
+namespace itk
+{
+/**
+ *\class CurvilinearFFTImageFilterInitFactory
+ * \brief Initialize FFT image filter factory backends.
+ *
+ * The purpose of CurvilinearFFTImageFilterInitFactory is to perform
+ * one-time registration of factory objects that handle
+ * creation of FFT image filter classes as applied to
+ * CurvilinearArraySpecialCoordinatesImage objects
+ * through the ITK object factory singleton mechanism.
+ *
+ * By default ITK registers Vnl FFT backends to operate on
+ * rectangular `itk::Image` inputs and outputs. ITKUltrasound
+ * expands default availability to apply FFTs to
+ * curvilinear images.
+ *
+ * \ingroup FourierTransform
+ * \ingroup ITKFFT
+ * \ingroup ITKSystemObjects
+ * \ingroup Ultrasound
+ */
+class Ultrasound_EXPORT CurvilinearFFTImageFilterInitFactory : public LightObject
+{
+public:
+  ITK_DISALLOW_COPY_AND_MOVE(CurvilinearFFTImageFilterInitFactory);
+
+  /** Standard class type aliases. */
+  using Self = CurvilinearFFTImageFilterInitFactory;
+  using Superclass = LightObject;
+  using Pointer = SmartPointer<Self>;
+  using ConstPointer = SmartPointer<const Self>;
+
+  /** Method for class instantiation. */
+  itkFactorylessNewMacro(Self);
+
+  /** Run-time type information (and related methods). */
+  itkTypeMacro(CurvilinearFFTImageFilterInitFactory, LightObject);
+
+  /** Mimic factory interface for Python initialization  */
+  static void
+  RegisterOneFactory()
+  {
+    RegisterFactories();
+  }
+
+  /** Register all Curvilinear FFT factories */
+  static void
+  RegisterFactories();
+
+protected:
+  CurvilinearFFTImageFilterInitFactory();
+  ~CurvilinearFFTImageFilterInitFactory() override = default;
+};
+} // end namespace itk
+
+#endif // itkCurvilinearFFTImageFilterInitFactory_h

itk-module.cmake

@@ -29,6 +29,8 @@ itk_module(Ultrasound
   TEST_DEPENDS
     ITKVideoCore
     ITKVideoIO
+  FACTORY_NAMES
+    "FFTImageFilterInit::Curvilinear"
   EXCLUDE_FROM_DEFAULT
   ENABLE_SHARED
   DESCRIPTION

src/CMakeLists.txt

@@ -1,4 +1,5 @@
 set(Ultrasound_SRCS
+itkCurvilinearFFTImageFilterInitFactory.cxx
   itkHDF5UltrasoundImageIOFactory.cxx
   itkHDF5UltrasoundImageIO.cxx
   itkTextProgressBarCommand.cxx