SimpleITK · dave3d · Apr 13, 2026 · Apr 14, 2026 · Apr 14, 2026
diff --git a/CMake/sitkGenerateExamples.cmake b/CMake/sitkGenerateExamples.cmake
@@ -0,0 +1,241 @@
+include_guard(GLOBAL)
+
+# ---------------------------------------------------------------------------
+# sitkGenerateExamples.cmake
+#
+# Provides sitk_generate_filter_examples(), which reads
+# Examples/example_filter_list.yaml and registers add_custom_command rules
+# that expand every Jinja2 template in
+# ExpandTemplateGenerator/templates/examples/ for each listed filter.
+#
+# A custom target "GenerateFilterExamples" is created that depends on all
+# generated files.  The generated files are written into the source tree
+# (Examples/<FilterName>/) so that they can be reviewed and committed.
+#
+# Requirements:
+#   - SimpleITK_Python_EXECUTABLE must be set (or findable via find_package).
+#   - SimpleITK_EXPANSION_SCRIPT must be set (or derivable from this file's
+#     location relative to ExpandTemplateGenerator/).
+#   - The pyyaml and jinja2 Python packages must be installed.
+# ---------------------------------------------------------------------------
+
+# --- Locate Python ----------------------------------------------------------
+
+if(NOT DEFINED SimpleITK_Python_EXECUTABLE)
+  if(DEFINED Python_EXECUTABLE)
+    set(SimpleITK_Python_EXECUTABLE "${Python_EXECUTABLE}")
+  else()
+    find_package(Python 3.9...<4 REQUIRED COMPONENTS Interpreter)
+    set(SimpleITK_Python_EXECUTABLE "${Python_EXECUTABLE}")
+  endif()
+  set(
+    SimpleITK_Python_EXECUTABLE
+    "${SimpleITK_Python_EXECUTABLE}"
+    CACHE FILEPATH
+    "Python executable used for code generation."
+  )
+endif()
+
+# --- Locate the expansion script --------------------------------------------
+
+if(NOT DEFINED SimpleITK_EXPANSION_SCRIPT)
+  # CMAKE_CURRENT_LIST_DIR is <src>/CMake/; sibling dir holds the script.
+  get_filename_component(
+    _sitk_source_root
+    "${CMAKE_CURRENT_LIST_DIR}/.."
+    ABSOLUTE
+  )
+  set(
+    SimpleITK_EXPANSION_SCRIPT
+    "${_sitk_source_root}/ExpandTemplateGenerator/ExpandTemplate.py"
+    CACHE INTERNAL
+    "Python script used to expand templates."
+    FORCE
+  )
+endif()
+
+if(NOT EXISTS "${SimpleITK_EXPANSION_SCRIPT}")
+  message(
+    FATAL_ERROR
+    "sitkGenerateExamples: ExpandTemplate.py not found at "
+    "'${SimpleITK_EXPANSION_SCRIPT}'. "
+    "Set SimpleITK_EXPANSION_SCRIPT to its location."
+  )
+endif()
+
+# ---------------------------------------------------------------------------
+# sitk_generate_filter_examples()
+#
+# Reads Examples/example_filter_list.yaml, then for every filter name listed
+# creates add_custom_command rules to expand all example Jinja2 templates.
+# All generated files are placed in Examples/<FilterName>/ inside the source
+# tree so they can be committed alongside hand-written examples.
+#
+# A single custom target "GenerateFilterExamples" is created that depends on
+# every output file.
+#
+# Optional keyword arguments
+#   FILTER_LIST_YAML  <path>   Override the default filter list YAML location.
+#   YAML_DIR          <path>   Override the default Code/BasicFilters/yaml/ dir.
+#   TEMPLATE_DIR      <path>   Override the default templates/examples/ dir.
+#   OUTPUT_BASE       <path>   Override the default Examples/ output directory.
+# ---------------------------------------------------------------------------
+function(sitk_generate_filter_examples)
+  cmake_parse_arguments(
+    _GFE
+    ""
+    "FILTER_LIST_YAML;YAML_DIR;TEMPLATE_DIR;OUTPUT_BASE"
+    ""
+    ${ARGN}
+  )
+
+  # Resolve source root relative to this file.
+  get_filename_component(_src_root "${CMAKE_CURRENT_LIST_DIR}/.." ABSOLUTE)
+
+  # Apply defaults for any arguments not provided.
+  if(NOT _GFE_FILTER_LIST_YAML)
+    set(_GFE_FILTER_LIST_YAML "${_src_root}/Examples/example_filter_list.yaml")
+  endif()
+  if(NOT _GFE_YAML_DIR)
+    set(_GFE_YAML_DIR "${_src_root}/Code/BasicFilters/yaml")
+  endif()
+  if(NOT _GFE_TEMPLATE_DIR)
+    set(
+      _GFE_TEMPLATE_DIR
+      "${_src_root}/ExpandTemplateGenerator/templates/examples"
+    )
+  endif()
+  if(NOT _GFE_OUTPUT_BASE)
+    set(_GFE_OUTPUT_BASE "${_src_root}/Examples")
+  endif()
+
+  # --- Read the filter list from YAML at configure time --------------------
+
+  execute_process(
+    COMMAND
+      "${SimpleITK_Python_EXECUTABLE}" -c
+      "import sys, yaml\n\
+try:\n\
+    from yaml import CSafeLoader as Loader\n\
+except ImportError:\n\
+    from yaml import SafeLoader as Loader\n\
+data = yaml.load(open(sys.argv[1]), Loader=Loader)\n\
+filters = data.get('filters', [])\n\
+print(';'.join(str(f) for f in filters))"
+      "${_GFE_FILTER_LIST_YAML}"
+    OUTPUT_VARIABLE _filter_names
+    RESULT_VARIABLE _ret
+    OUTPUT_STRIP_TRAILING_WHITESPACE
+    ERROR_STRIP_TRAILING_WHITESPACE
+  )
+
+  if(_ret)
+    message(
+      FATAL_ERROR
+      "sitkGenerateExamples: Failed to parse filter list from "
+      "'${_GFE_FILTER_LIST_YAML}'."
+    )
+  endif()
+
+  if(NOT _filter_names)
+    message(
+      WARNING
+      "sitkGenerateExamples: No filters found in '${_GFE_FILTER_LIST_YAML}'."
+    )
+    return()
+  endif()
+
+  # --- Template → output filename table ------------------------------------
+  #
+  # Pairs of (template_file  output_filename_pattern).
+  # The pattern may use '*' as a placeholder for the filter name.
+  # ---------------------------------------------------------------------------
+
+  set(
+    _template_output_pairs
+    "ExampleTemplate.py.jinja"
+    "*.py"
+    "ExampleTemplate.cxx.jinja"
+    "*.cxx"
+    "ExampleTemplate.cs.jinja"
+    "*.cs"
+    "ExampleTemplate.java.jinja"
+    "*.java"
+    "ExampleTemplate.lua.jinja"
+    "*.lua"
+    "ExampleTemplate.R.jinja"
+    "*.R"
+    "ExampleTemplate.rb.jinja"
+    "*.rb"
+    "ExampleDocumentation.rst.jinja"
+    "Documentation.rst"
+    "ExampleCMakeLists.cmake.jinja"
+    "CMakeLists.txt"
+  )
+
+  # Collect all .jinja files for use as blanket DEPENDS.
+  file(GLOB _all_jinja_files "${_GFE_TEMPLATE_DIR}/*.jinja")
+
+  # --- Create custom commands per filter × template ------------------------
+
+  set(_all_outputs)
+
+  foreach(_filter IN LISTS _filter_names)
+    set(_config_file "${_GFE_YAML_DIR}/${_filter}.yaml")
+
+    if(NOT EXISTS "${_config_file}")
+      message(
+        WARNING
+        "sitkGenerateExamples: No YAML file found for '${_filter}' "
+        "at '${_config_file}'. Skipping."
+      )
+      continue()
+    endif()
+
+    set(_out_dir "${_GFE_OUTPUT_BASE}/${_filter}")
+
+    # Iterate over template/output pairs (step 2 through the list).
+    list(LENGTH _template_output_pairs _pair_list_len)
+    math(EXPR _last_idx "${_pair_list_len} - 1")
+
+    foreach(_i RANGE 0 ${_last_idx} 2)
+      list(GET _template_output_pairs "${_i}" _template_file)
+      math(EXPR _j "${_i} + 1")
+      list(GET _template_output_pairs "${_j}" _output_pattern)
+
+      # Replace '*' wildcard with the filter name.
+      string(REPLACE "*" "${_filter}" _output_name "${_output_pattern}")
+      set(_output_file "${_out_dir}/${_output_name}")
+
+      add_custom_command(
+        OUTPUT
+          "${_output_file}"
+        COMMAND
+          "${CMAKE_COMMAND}" -E make_directory "${_out_dir}"
+        COMMAND
+          "${SimpleITK_Python_EXECUTABLE}" "${SimpleITK_EXPANSION_SCRIPT}"
+          "${_config_file}" "${_template_file}" -D "${_GFE_TEMPLATE_DIR}" -o
+          "${_output_file}"
+        DEPENDS
+          "${_config_file}"
+          "${_GFE_TEMPLATE_DIR}/${_template_file}"
+          "${SimpleITK_EXPANSION_SCRIPT}"
+          "${_GFE_FILTER_LIST_YAML}"
+          ${_all_jinja_files}
+        COMMENT "Generating example for ${_filter}: ${_output_name}"
+        VERBATIM
+      )
+
+      list(APPEND _all_outputs "${_output_file}")
+    endforeach()
+  endforeach()
+
+  # --- Top-level target ------------------------------------------------------
+
+  add_custom_target(
+    GenerateFilterExamples
+    DEPENDS
+      ${_all_outputs}
+    COMMENT "Generating all filter example files"
+  )
+endfunction()
diff --git a/Code/Common/include/sitkLogger.h b/Code/Common/include/sitkLogger.h
@@ -54,11 +54,7 @@ class SITKCommon_EXPORT LoggerBase : public ObjectOwnedBase
   ~LoggerBase() override;
 
   virtual void
-  DisplayText(const char * t)
-#ifndef SWIGR
-    = 0
-#endif
-    ;
+  DisplayText(const char * t);
 
   virtual void
   DisplayErrorText(const char * t);

diff --git a/Code/Common/src/sitkLogger.cxx b/Code/Common/src/sitkLogger.cxx
@@ -124,6 +124,10 @@ LoggerBase::LoggerBase() = default;
 
 LoggerBase::~LoggerBase() = default;
 
+void
+LoggerBase::DisplayText(const char * txt)
+{}
+
 ITKLogger
 LoggerBase::SetAsGlobalITKLogger()
 {

diff --git a/Examples/.gitignore b/Examples/.gitignore
@@ -0,0 +1,38 @@
+# Generated filter example directories (created by GenerateFilterExamples CMake target)
+
+DiscreteGaussianImageFilter/
+SmoothingRecursiveGaussianImageFilter/
+MedianImageFilter/
+BilateralImageFilter/
+MeanImageFilter/
+SobelEdgeDetectionImageFilter/
+CannyEdgeDetectionImageFilter/
+LaplacianImageFilter/
+LaplacianRecursiveGaussianImageFilter/
+BinaryDilateImageFilter/
+BinaryErodeImageFilter/
+GrayscaleDilateImageFilter/
+GrayscaleErodeImageFilter/
+ThresholdImageFilter/
+OtsuThresholdImageFilter/
+BinaryThresholdImageFilter/
+AddImageFilter/
+SubtractImageFilter/
+MultiplyImageFilter/
+DivideImageFilter/
+AbsImageFilter/
+SquareImageFilter/
+SqrtImageFilter/
+RescaleIntensityImageFilter/
+NormalizeImageFilter/
+ResampleImageFilter/
+FlipImageFilter/
+PermuteAxesImageFilter/
+StatisticsImageFilter/
+MinimumMaximumImageFilter/
+LabelStatisticsImageFilter/
+ConnectedComponentImageFilter/
+LabelShapeStatisticsImageFilter/
+GradientMagnitudeImageFilter/
+GradientMagnitudeRecursiveGaussianImageFilter/
+ThresholdImageFilter/
diff --git a/Examples/CMakeLists.txt b/Examples/CMakeLists.txt
@@ -69,6 +69,69 @@ add_subdirectory(CppInPlace)
 add_subdirectory(SliceBySliceDecorator)
 add_subdirectory(Logging)
 
+# ---------------------------------------------------------------------------
+# Generated filter examples
+#
+# The GenerateFilterExamples target expands Jinja2 templates for every filter
+# listed in example_filter_list.yaml and writes the output into
+# Examples/<FilterName>/ in the source tree.
+#
+# Run the target once (or whenever filter YAMLs or templates change) to
+# regenerate the files:
+#
+#   cmake --build <build-dir> --target GenerateFilterExamples
+#
+# After generation, each filter subdirectory is picked up automatically by
+# the add_subdirectory loop below.
+# ---------------------------------------------------------------------------
+
+if(CMAKE_PROJECT_NAME STREQUAL "SimpleITK")
+  include(sitkGenerateExamples)
+  sitk_generate_filter_examples()
+endif()
+
+# Add every generated filter example subdirectory that already exists on disk.
+set(
+  _sitk_example_filter_list
+  "${CMAKE_CURRENT_SOURCE_DIR}/example_filter_list.yaml"
+)
+if(EXISTS "${_sitk_example_filter_list}")
+  # Resolve a Python interpreter for YAML parsing (may not be set in standalone mode).
+  if(DEFINED SimpleITK_Python_EXECUTABLE)
+    set(_sitk_py "${SimpleITK_Python_EXECUTABLE}")
+  elseif(DEFINED Python_EXECUTABLE)
+    set(_sitk_py "${Python_EXECUTABLE}")
+  else()
+    find_package(Python 3.9...<4 QUIET COMPONENTS Interpreter)
+    set(_sitk_py "${Python_EXECUTABLE}")
+  endif()
+
+  execute_process(
+    COMMAND
+      "${_sitk_py}" -c
+      "import sys, yaml\n\
+try:\n\
+    from yaml import CSafeLoader as Loader\n\
+except ImportError:\n\
+    from yaml import SafeLoader as Loader\n\
+data = yaml.load(open(sys.argv[1]), Loader=Loader)\n\
+print(';'.join(str(f) for f in data.get('filters', [])))"
+      "${_sitk_example_filter_list}"
+    OUTPUT_VARIABLE _sitk_generated_filters
+    OUTPUT_STRIP_TRAILING_WHITESPACE
+    ERROR_STRIP_TRAILING_WHITESPACE
+  )
+  foreach(_sitk_filter IN LISTS _sitk_generated_filters)
+    if(EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/${_sitk_filter}/CMakeLists.txt")
+      add_subdirectory("${_sitk_filter}")
+    endif()
+  endforeach()
+  unset(_sitk_generated_filters)
+  unset(_sitk_filter)
+endif()
+unset(_sitk_example_filter_list)
+unset(_sitk_py)
+
 macro(add_language_subdirectory lang)
   string(TOUPPER ${lang} LANG)
   if(WRAP_${LANG})