ENH: Add ctype aliases for numeric types of specific sizes to Python

Wrapping/Generators/Python/Tests/CMakeLists.txt

@@ -281,3 +281,9 @@ itk_python_add_test(
   COMMAND
     ${CMAKE_CURRENT_SOURCE_DIR}/test_gil_release_safety.py
 )
+
+itk_python_add_test(
+  NAME CTypeTest
+  COMMAND
+    ${CMAKE_CURRENT_SOURCE_DIR}/test_ctype.py
+)

Wrapping/Generators/Python/Tests/test_ctype.py

@@ -0,0 +1,75 @@
+# ==========================================================================
+#
+#   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
+#
+#          https://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.
+#
+# ==========================================================================
+
+import itk
+import unittest
+import numpy as np
+import os
+
+
+class CTypeTestCase(unittest.TestCase):
+    """Tests itkCType"""
+
+    def test_dtype_of_ctype_aliases_for_specific_sizes(self) -> None:
+        """Tests that each `ctype` alias for a specific size has the corresponding `dtype`"""
+
+        # Check uint8 to uint64 and int8 to int64:
+        for number_of_bits in (8, 16, 32, 64):
+            self.assertEqual(
+                getattr(itk, f"int{number_of_bits}_ctype").dtype,
+                getattr(np, f"int{number_of_bits}"),
+            )
+            self.assertEqual(
+                getattr(itk, f"uint{number_of_bits}_ctype").dtype,
+                getattr(np, f"uint{number_of_bits}"),
+            )
+
+        # Check float32 and float64:
+        for number_of_bits in (32, 64):
+            self.assertEqual(
+                getattr(itk, f"float{number_of_bits}_ctype").dtype,
+                getattr(np, f"float{number_of_bits}"),
+            )
+
+    def test_ctype_aliases_for_64_bit_integers(self) -> None:
+        """Tests int64_ctype and uint64_type, for both Windows and non-Windows"""
+
+        if os.name == "nt":
+            # On Windows, only `long long` integer types (SLL and ULL) are 64-bit.
+            self.assertEqual(
+                itk.int64_ctype,
+                itk.SLL,
+            )
+            self.assertEqual(
+                itk.uint64_ctype,
+                itk.ULL,
+            )
+        else:
+            # On Linux and MacOS, `long` integer types (SL and UL) are already 64-bit.
+            self.assertEqual(
+                itk.int64_ctype,
+                itk.SL,
+            )
+            self.assertEqual(
+                itk.uint64_ctype,
+                itk.UL,
+            )
+
+
+if __name__ == "__main__":
+    unittest.main()

Wrapping/Generators/Python/itk/__init__.py

@@ -48,6 +48,16 @@
     SI,
     SLL,
     B,
+    float32_ctype,
+    float64_ctype,
+    uint8_ctype,
+    uint16_ctype,
+    uint32_ctype,
+    uint64_ctype,
+    int8_ctype,
+    int16_ctype,
+    int32_ctype,
+    int64_ctype,
     ST,
     IT,
     OT,

Wrapping/Generators/Python/itk/support/types.py

@@ -145,6 +145,18 @@ def initialize_c_types_once(cls) -> tuple[Self, ...]:
     B,
 ) = itkCType.initialize_c_types_once()
 
+# Aliases for numeric types of specific sizes (specified by their number of bits)
+float32_ctype = F
+float64_ctype = D
+uint8_ctype = UC
+uint16_ctype = US
+uint32_ctype = UI
+uint64_ctype = UL if UL.dtype.itemsize == 8 else ULL
+int8_ctype = SC
+int16_ctype = SS
+int32_ctype = SI
+int64_ctype = SL if SL.dtype.itemsize == 8 else SLL
+
 # Aliases for SizeValueType, IdentifierType, OffsetType
 ST = UL
 IT = UL