ENH: Add ElastixLogLevel to the ITK interface

Added `GetLogLevel` and `SetLogLevel` member functions to both `itk::ElastixRegistrationMethod` and `itk::TransformixFilter`, allowing the user to reduce the amount of logging from elastix and transformix, both to the log file and the console (standard output).

Core/Kernel/elxlog.h

@@ -30,7 +30,7 @@ namespace elastix
 class log
 {
 public:
-  enum class level
+  enum class level : uint8_t
   {
     info,
     warn,
@@ -56,7 +56,7 @@ class log
     guard(const std::string & log_filename,
           const bool          do_log_to_file,
           const bool          do_log_to_stdout,
-          const level         log_level = {});
+          const level         log_level);
 
     /** Does reset the logging system. */
     ~guard();

Core/Main/GTesting/itkElastixRegistrationMethodGTest.cxx

@@ -144,6 +144,38 @@ Test_WriteBSplineTransformToItkFileFormat(const std::string & rootOutputDirector
 } // namespace
 
 
+static_assert(sizeof(itk::ElastixLogLevel) == sizeof(elx::log::level),
+              "The log level enum types should have the same size!");
+
+static_assert(sizeof(itk::ElastixLogLevel) == 1, "The log level enum type should have just one byte!");
+
+static_assert(itk::ElastixLogLevel::Info == itk::ElastixLogLevel{}, "The default log level should be `Info`!");
+
+static_assert(static_cast<int>(itk::ElastixLogLevel::Info) == static_cast<int>(elx::log::level::info) &&
+                static_cast<int>(itk::ElastixLogLevel::Warning) == static_cast<int>(elx::log::level::warn) &&
+                static_cast<int>(itk::ElastixLogLevel::Error) == static_cast<int>(elx::log::level::err) &&
+                static_cast<int>(itk::ElastixLogLevel::Off) == static_cast<int>(elx::log::level::off),
+              "Corresponding log level enumerators should have the same underlying integer value!");
+
+
+GTEST_TEST(itkElastixRegistrationMethod, LogLevel)
+{
+  using ImageType = itk::Image<float>;
+  elx::DefaultConstruct<itk::ElastixRegistrationMethod<ImageType, ImageType>> elastixRegistrationMethod;
+
+  ASSERT_EQ(elastixRegistrationMethod.GetLogLevel(), itk::ElastixLogLevel{});
+
+  for (const auto logLevel : { itk::ElastixLogLevel::Info,
+                               itk::ElastixLogLevel::Warning,
+                               itk::ElastixLogLevel::Error,
+                               itk::ElastixLogLevel::Off })
+  {
+    elastixRegistrationMethod.SetLogLevel(logLevel);
+    EXPECT_EQ(elastixRegistrationMethod.GetLogLevel(), logLevel);
+  }
+}
+
+
 GTEST_TEST(itkElastixRegistrationMethod, IsDefaultInitialized)
 {
   constexpr auto ImageDimension = 2U;

Core/Main/itkElastixLogLevel.h

@@ -0,0 +1,53 @@
+/*=========================================================================
+ *
+ *  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.
+ *
+ *=========================================================================*/
+/*=========================================================================
+ *
+ *  Copyright UMC Utrecht and contributors
+ *
+ *  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 itkElastixLogLevel_h
+#define itkElastixLogLevel_h
+
+#include "itkIntTypes.h"
+
+namespace itk
+{
+/** The level of logging from elastix and/or transformix */
+enum ElastixLogLevel : uint8_t
+{
+  Info,    //!< Log all messages, even the ones that are only informative.
+  Warning, //!< Log the error messages, as well as the warnings.
+  Error,   //!< Log only the error messages.
+  Off      //!< Do not log any messages.
+};
+
+} // namespace itk
+
+#endif

Core/Main/itkElastixRegistrationMethod.h

@@ -36,6 +36,7 @@
 #define itkElastixRegistrationMethod_h
 
 #include "itkImageSource.h"
+#include "itkElastixLogLevel.h"
 
 #include "elxElastixMain.h"
 #include "elxElastixTemplate.h"
@@ -252,6 +253,9 @@ class ITK_TEMPLATE_EXPORT ElastixRegistrationMethod : public itk::ImageSource<TF
     m_EnableOutput = false;
   }
 
+  itkSetMacro(LogLevel, ElastixLogLevel);
+  itkGetConstMacro(LogLevel, ElastixLogLevel);
+
   itkSetMacro(NumberOfThreads, int);
   itkGetConstMacro(NumberOfThreads, int);
 
@@ -318,6 +322,8 @@ class ITK_TEMPLATE_EXPORT ElastixRegistrationMethod : public itk::ImageSource<TF
   bool m_LogToConsole{ false };
   bool m_LogToFile{ false };
 
+  ElastixLogLevel m_LogLevel{};
+
   int m_NumberOfThreads{ 0 };
 
   unsigned int m_InputUID{ 0 };

Core/Main/itkElastixRegistrationMethod.hxx

@@ -188,7 +188,10 @@ ElastixRegistrationMethod<TFixedImage, TMovingImage>::GenerateData()
   }
 
   // Setup logging.
-  const elx::log::guard logGuard(logFileName, m_EnableOutput && m_LogToFile, m_EnableOutput && m_LogToConsole);
+  const elx::log::guard logGuard(logFileName,
+                                 m_EnableOutput && m_LogToFile,
+                                 m_EnableOutput && m_LogToConsole,
+                                 static_cast<elastix::log::level>(m_LogLevel));
 
   // Run the (possibly multiple) registration(s)
   for (unsigned int i = 0; i < parameterMapVector.size(); ++i)

Core/Main/itkTransformixFilter.h

@@ -35,6 +35,7 @@
 #ifndef itkTransformixFilter_h
 #define itkTransformixFilter_h
 
+#include "itkElastixLogLevel.h"
 #include "itkImageSource.h"
 #include "itkMesh.h"
 #include "itkTransformBase.h"
@@ -212,6 +213,9 @@ class ITK_TEMPLATE_EXPORT TransformixFilter : public ImageSource<TMovingImage>
     m_EnableOutput = false;
   }
 
+  itkSetMacro(LogLevel, ElastixLogLevel);
+  itkGetConstMacro(LogLevel, ElastixLogLevel);
+
   /** Sets an (optional) input mesh. An Update() will transform its points, and store them in the output mesh.  */
   itkSetConstObjectMacro(InputMesh, MeshType);
 
@@ -288,6 +292,8 @@ class ITK_TEMPLATE_EXPORT TransformixFilter : public ImageSource<TMovingImage>
   bool m_LogToConsole{ false };
   bool m_LogToFile{ false };
 
+  ElastixLogLevel m_LogLevel{};
+
   typename MeshType::ConstPointer m_InputMesh{ nullptr };
   typename MeshType::Pointer      m_OutputMesh{ nullptr };
 

Core/Main/itkTransformixFilter.hxx

@@ -140,7 +140,10 @@ TransformixFilter<TMovingImage>::GenerateData()
   const std::string logFileName = m_OutputDirectory + (m_LogFileName.empty() ? "transformix.log" : m_LogFileName);
 
   // Setup logging.
-  const elx::log::guard logGuard(logFileName, m_EnableOutput && m_LogToFile, m_EnableOutput && m_LogToConsole);
+  const elx::log::guard logGuard(logFileName,
+                                 m_EnableOutput && m_LogToFile,
+                                 m_EnableOutput && m_LogToConsole,
+                                 static_cast<elastix::log::level>(m_LogLevel));
 
   // Instantiate transformix
   const auto transformixMain = elx::TransformixMain::New();